Refine
Year of publication
Institute
- Fachbereich Medizintechnik und Technomathematik (1571) (remove)
Has Fulltext
- no (1571) (remove)
Language
- English (1571) (remove)
Document Type
- Article (1316)
- Conference Proceeding (135)
- Book (43)
- Part of a Book (43)
- Doctoral Thesis (18)
- Other (6)
- Patent (4)
- Preprint (3)
- Conference: Meeting Abstract (1)
- Habilitation (1)
Keywords
- LAPS (4)
- Natural language processing (4)
- CellDrum (3)
- Field-effect sensor (3)
- Light-addressable potentiometric sensor (3)
- Paired sample (3)
- hydrogen peroxide (3)
- impedance spectroscopy (3)
- Bacillus atrophaeus (2)
- Biocomposites (2)
- Boundary integral equations (2)
- Clustering (2)
- Conductive boundary condition (2)
- Empirical process (2)
- Force (2)
- Goodness-of-fit test (2)
- Incomplete data (2)
- Independence test (2)
- Information extraction (2)
- Iterative learning control (2)
- Limit analysis (2)
- Machine learning (2)
- Natural fibres (2)
- Parametric bootstrap (2)
- Polymer-matrix composites (2)
- Raman spectroscopy (2)
- Shakedown analysis (2)
- Simulation (2)
- Stiffness (2)
- Stress concentrations (2)
- Transmission eigenvalues (2)
- biopotential electrodes (2)
- constructive alignment (2)
- damage (2)
- examination (2)
- field-effect sensor (2)
- frequency mixing magnetic detection (2)
- humans (2)
- likelihood ratio test (2)
- locomotion (2)
- long-term retention (2)
- multimodal (2)
- muscle fascicle behavior (2)
- not identically distributed (2)
- practical learning (2)
- tobacco mosaic virus (TMV) (2)
- ultrasound (2)
- ultrasound imaging (2)
- (Bio)degradation (1)
- Acceleration (1)
- Achilles tendon (1)
- Active learning (1)
- Adaptive control (1)
- Afterload (1)
- Ageing (1)
- Agent-based modeling (1)
- Agent-based simulation (1)
- AlterG (1)
- Alzheimer's disease (1)
- Analytical models (1)
- Anastomotic leakage (1)
- Anatomy (1)
- Annulus Fibrosus (1)
- Architectural gear ratio (1)
- Assistive technology (1)
- Asymptotic efficiency (1)
- Asymptotic relative efficiency (1)
- Autolysis (1)
- Automatic control (1)
- Bacillus atrophaeus spores (1)
- Bacillus sp (1)
- Balance (1)
- Biomechanical simulation (1)
- Biomolecular logic gate (1)
- Biosolubilization (1)
- Bladder (1)
- Bone sawing (1)
- Booster Station (1)
- Bootstrap (1)
- Bootstrapping (1)
- Boundary integral equations, (1)
- Brownian Pillow (1)
- CNOT (1)
- Calorimetric gas sensor (1)
- Capacitive field-effect (1)
- Capacitive model (1)
- Cardiac myocytes (1)
- Cardiac tissue (1)
- Categorial variable (1)
- Cell permeability (1)
- Cellular force (1)
- Cementoblast (1)
- Censored data (1)
- Chance constrained programming (1)
- Chemical images (1)
- Chemical imaging (1)
- Chemical imaging sensor (1)
- Chemical sensor (1)
- Circular Dichroism (1)
- Cloud Computing (1)
- Cloud Service Broker (1)
- Co-managed care (1)
- Coal (1)
- Coat protein (1)
- Coefficient of ocular rigidity (1)
- Collective risk model (1)
- Comparative simulation (1)
- Competitiveness (1)
- Complex System (1)
- Complex-valued eigenvalues (1)
- Compliance (1)
- Compression (1)
- Computational biomechanics (1)
- Concomitant (1)
- Conductive Boundary Condition (1)
- Conservation laws (1)
- Constitutive model (1)
- Contractile tension (1)
- Contractility (1)
- Corneo-scleral shell (1)
- Coverage probability (1)
- Cramér-von-Mises statistic (1)
- Cramér-von-Mises test (1)
- Cross border adjustment mechanism (1)
- Crámer–von-Mises distance (1)
- C–V method (1)
- DNA (1)
- DNA biosensor (1)
- DNA hybridization (1)
- DPA (dipicolinic acid) (1)
- Damage mechanics theory (1)
- Database (1)
- Decomposition (1)
- Deep learning (1)
- Dehydrogenase (1)
- Diaphorase (1)
- Differential tonometry (1)
- Dimensional splitting (1)
- Disc Degeneration (1)
- Discontinuous fractures (1)
- Discrete Optimization (1)
- Drug simulation (1)
- Dry surfaces (1)
- E-Mobility (1)
- EEG (1)
- EIS capacitive sensor (1)
- ES-FEM (1)
- Eigenvalue trajectories (1)
- Elderly (1)
- Electrolyte–insulator–semiconductor (1)
- Electromagnetism (1)
- Electromechanical modeling (1)
- Elemental (1)
- End-to-end colorectal anastomosis (1)
- Endothelial cells (1)
- Endothelial dysfunction (1)
- Energy dispatch (1)
- Energy market (1)
- Energy market design (1)
- Energy-intensive industry (1)
- Entropy solution (1)
- Enzymatic biosensor (1)
- Enzyme biosensor (1)
- Enzyme coverage (1)
- Enzyme logic gate (1)
- Enzyme nanocarrier (1)
- Equivalence test (1)
- Esophageal Doppler monitor (1)
- Evolution of damage (1)
- Exponential Euler scheme, (1)
- Exponential time differencing (1)
- Extension fracture (1)
- Extension strain criterion (1)
- External knee adduction moments (1)
- Eyeball (1)
- FGF23 (1)
- FS-FEM (1)
- Fall prevention (1)
- Field effect (1)
- Field-effect biosensor (1)
- Field-effect device (1)
- Finite difference methods (1)
- Finite element analysis (1)
- Finite element analysis (FEA) (1)
- Finite element modelling (1)
- Floor prices (1)
- Focusing (1)
- Forces (1)
- Fracture configuration (1)
- Fracture simulation (1)
- Freeze–thaw process (1)
- Frequency adaption (1)
- Frequency mixing magnetic detection (1)
- Functional Delta Method (1)
- Gamma distribution (1)
- Glaucoma (1)
- Glucose biosensor (1)
- Glucose oxidase (1)
- Gold nanoparticle (1)
- Goodness-of-fit tests for uniformity (1)
- Grid Computing (1)
- Ground-level falls (1)
- Growth modelling (1)
- H2 (1)
- Hadamard differentiability (1)
- Haemodialysis (1)
- Handbike (1)
- Heart tissue culture (1)
- Helmholtz equation (1)
- Heterostructure (1)
- Higher-order codes (1)
- Hodgkin–Huxley models (1)
- Hoeffding-Blum-Kiefer-Rosenblatt independence test (1)
- Homogenization (1)
- Hotelling’s T² test (1)
- Human-Computer interaction (1)
- Hydrogen peroxide (1)
- Hydrogenotrophic methanogens (1)
- Image Reconstruction (1)
- Impedance Spectroscopy (1)
- Impedance spectroscopy (1)
- Implicit methods (1)
- Induced pluripotent stem cells (1)
- Information Extraction (1)
- Inotropic compounds (1)
- Instruments (1)
- Integrated empirical distribution (survival) function (1)
- Interior Neumann eigenvalues (1)
- Interior transmission eigenvalues (1)
- Interior transmission problem (1)
- Intervertebral Disc (1)
- Intradiscal Pressure (1)
- Inverse Scattering (1)
- Inverse dynamic problem (1)
- Inverse kinematic problem (1)
- Inverse scattering (1)
- Inverse spectral problem (1)
- Ion channels (1)
- Kinetic energy (1)
- Klotho (1)
- Knee (1)
- LPS (1)
- Lab-on-Chip (1)
- Label-free detection (1)
- Langevin theory (1)
- Layer-by-layer adsorption (1)
- LbL films (1)
- Light-addressable Potentiometric Sensor (1)
- Lipopolysaccharide (1)
- Liver (1)
- Load modeling (1)
- Long COVID (1)
- MOS (1)
- Magnetic nanoparticles (1)
- Manipulated variables (1)
- Marginal homogeneity (1)
- Marginal homogeneity test (1)
- Market modeling (1)
- Matrix exponential (1)
- Measurement (1)
- Mechanical simulation (1)
- Mechanotransduction (1)
- Metascintillator (1)
- Methane (1)
- Methanogenesis (1)
- Microbial adhesion (1)
- Microcirculation (1)
- Micromagnetic simulation (1)
- Mild cognitive impairment (1)
- Mobility (1)
- Mobility tests (1)
- Mobility transition (1)
- Mohr–Coulomb criterion (1)
- Monotone methods (1)
- Multi-criteria decision analysis (1)
- Multi-dimensional partial differential equations (1)
- Multi-sample problem (1)
- Multianalyte detection (1)
- Multimode failure (1)
- Multiple TOF kernels (1)
- Muscle (1)
- Muscle Fascicle (1)
- Muscle Force (1)
- Muscle fibers (1)
- Musculoskeletal model (1)
- Musculoskeletal system (1)
- Myocardial infarction and cardiac death (1)
- NONOate (1)
- Natural Language Processing (1)
- Natural language understanding (1)
- Negative impedance convertor (1)
- Neural Network (1)
- Niacin (1)
- Nitric Oxide (1)
- Nitric Oxide Donor (1)
- Non-linear optimization (1)
- Non-parallel fissures (1)
- Nonequilibrium dynamics (1)
- Nonlinear Dynamics (1)
- Nonlinear PDEs (1)
- Nonlinear eigenvalue problems (1)
- Nucleus Pulposus (1)
- Numerical inversion of Laplace transforms (1)
- Numerical linear algebra (1)
- Numerics (1)
- O2 plasma (1)
- Ocular blood flow (1)
- Open Data (1)
- Open source (1)
- Organic light-emitting diode display (1)
- PTH (1)
- Parabolic SPDEs (1)
- Paralympic sport (1)
- Passive stretching (1)
- Pelvic floor dysfunction (1)
- Pelvic muscle (1)
- Penicillin (1)
- Pharmacology (1)
- Phosphate (1)
- Physiology (1)
- Poly(allylamine hydrochloride) (1)
- Poly(d,l-lacticacid) (1)
- Polyimide (1)
- Post-COVID-19 syndrome (1)
- Potential theory (1)
- Potentiometry (1)
- Preference assessment (1)
- Pressure-volume relationship (1)
- Process model (1)
- Product-integration (1)
- Profile Extraction (1)
- Profile extraction (1)
- Proximal humerus fracture (1)
- Pulsations (1)
- Pump System (1)
- Query learning (1)
- RVA (1)
- Reaction-diffusion systems (1)
- Real distinct pole (1)
- Real-time monitoring (1)
- Recombinant activated protein C (1)
- Reconstruction (1)
- Refining (1)
- Regionalization (1)
- Rehabilitation Technology and Prosthetics (1)
- Rehabilitation engineering (1)
- Relation classification (1)
- Reliability analysis (1)
- Reliability of structures (1)
- Renewable energy sources (1)
- Reproducible research (1)
- Resampling test (1)
- Resolvent Operator (1)
- Resonance-mode measurement (1)
- Retinal vessel analysis (1)
- Retinal vessels (1)
- Riboflavin (1)
- Robotic rehabilitation (1)
- Rotator cuff (1)
- Running (1)
- S-FEM (1)
- Sampling methods (1)
- ScaLAPACK (1)
- Semi-parametric random censorship model (1)
- Septic cardiomyopathy (1)
- Simultaneous determination (1)
- Sleep EEG (1)
- Sn₃O₄ (1)
- Source term (1)
- Spleen (1)
- Steel industry (1)
- Sterilisation process (1)
- Stochastic programming (1)
- Surface microorganisms (1)
- Surgical Navigation and Robotics (1)
- Surgical staplers (1)
- Survival analysis (1)
- Swabbing (1)
- TMV adsorption (1)
- TOF PET (1)
- Ta₂O₅ gate (1)
- Technical Operations Research (TOR) (1)
- Tendon Rupture (1)
- Tendon properties (1)
- Tension (1)
- Text Mining (1)
- Text mining (1)
- Thiamine (1)
- Time-series (1)
- Tinetti test (1)
- Tobacco mosaic virus (1)
- Tobacco mosaic virus (TMV) (1)
- Training (1)
- Transmission Eigenvalues (1)
- Trustworthy artificial intelligence (1)
- Uniaxial compression test (1)
- Ureter (1)
- Vapnik–Čhervonenkis class (1)
- Variable height stapler design (1)
- Vascular response (1)
- Vasomotions (1)
- Velocity (1)
- Visual field asymmetry (1)
- Vitamin A (1)
- Vitamin B (1)
- Vitamin D (1)
- Volterra integral equation (1)
- Volume of confidence regions (1)
- Volume status (1)
- Volumes of confidence regions (1)
- Workflow (1)
- Workflow Orchestration (1)
- XML (1)
- XOR (1)
- access control (1)
- acetoin (1)
- achilles tendon (1)
- actin cytoskeleton (1)
- adipose-derived stromal cells (ASCs) (1)
- adsorption (1)
- agility (1)
- allocation (1)
- anaesthetic complications (1)
- anisotropy (1)
- annealing (1)
- aortic perfusion (1)
- aquaculture (1)
- artificial olfactory image (1)
- asymptotic relative efficiency (1)
- authorization (1)
- barium strontium titanate (1)
- biaxial tensile experiment (1)
- biomechanics (1)
- biosensor (1)
- biosensors (1)
- bootstrap (1)
- calorimetric gas sensor (1)
- calorimetric gas sensor;hydrogen peroxide;wireless sensor system (1)
- capacitive field-effect biosensor (1)
- capacitive field-effect sensor (1)
- carbonized rice husk (1)
- cardiomyocyte biomechanics (1)
- catalytic metal (1)
- cell aerosolization (1)
- cell atomization (1)
- central symmetry test (1)
- cerebral small vessel disease (1)
- chance constrained programming (1)
- chemical sensor (1)
- chip-based sensor setup (1)
- cognitive impairment (1)
- community dwelling (1)
- complete block symmetry (1)
- computational fluid dynamics analysis (1)
- concrete (1)
- conditional excess distribution (1)
- conditional expectation principle (1)
- confidence interval (1)
- connective tissue (1)
- constitutive modeling (1)
- contactless conductivity sensor (1)
- containers (1)
- correlation (1)
- coupled Néel–Brownian relaxation dynamics (1)
- covariance principle (1)
- dental trauma (1)
- dialysis (1)
- difficult airway (1)
- distorted element (1)
- distribution strategy (1)
- double-lumen tube intubation (1)
- drop jump (1)
- eigensolvers (1)
- elastic scattering (1)
- electrical conductivity of liquids (1)
- electrolyte-insulator semiconductor sensor (EIS) (1)
- electromyography (1)
- electronic nose (1)
- endoluminal (1)
- endospores (1)
- energy absorption (1)
- energy dissipation (1)
- engines (1)
- enzymatic (bio)degradation (1)
- enzyme cascade (1)
- enzyme immobilization (1)
- exchangeability test (1)
- extracorporeal membrane oxygenation (1)
- fatty acid (1)
- field-effect structure (1)
- force generation (1)
- forecast (1)
- forehead EEG (1)
- framework (1)
- frequency mixing (1)
- functional data (1)
- gait (1)
- gas sensor (1)
- glucose oxidase (GOx) (1)
- goodness-of-fit test (1)
- grid computing (1)
- healthy aging (1)
- heavy metals (1)
- hiPS cardiomyocytes (1)
- high-intensity exercise (1)
- high-k material (1)
- history (1)
- horseradish peroxidase (HRP) (1)
- huge dimensional data (1)
- humic acid (1)
- hydroxylation (1)
- hyper-gravity (1)
- hyperelastic (1)
- hypo-gravity (1)
- immobilization (1)
- in-ear EEG (1)
- in-situ monitoring (1)
- independence test (1)
- intraclass correlation coefficient (1)
- key performance indicators (1)
- lable-free detection (1)
- libraries (1)
- light-addressable potentiometric sensor (1)
- light-addressing technologies (1)
- lignite (1)
- limit analysis (1)
- lipopolysaccharide (1)
- magnetic actuation (1)
- magnetic beads (1)
- magnetic biosensing (1)
- magnetic nanoparticles (1)
- magnetic relaxation (1)
- magnetic sandwich immunoassay (1)
- magnetic sensing (1)
- magnetic separation (1)
- magnetic tweezers (1)
- magnetophoretic velocity (1)
- mechanical buffer (1)
- metal-oxide-semiconductor structure (1)
- metathesis (1)
- method of fundamental solutions (1)
- microfluidics (1)
- micromagnetic simulation (1)
- multi-functional material (1)
- multinomial distribution (1)
- multiparametric immunoassays (1)
- multivariate normal distribution (1)
- muscle mechanics (1)
- nanobelts (1)
- non-simplex S-FEM elements (1)
- novel photoexcitation method (1)
- optical sensor setup (1)
- optical spore trapping (1)
- optical trapping (1)
- organosilanes (1)
- overload (1)
- parabolic flight (1)
- performance analysis (1)
- performance testing (1)
- physiology (1)
- plant virus detection (1)
- plug-based microfluidic device (1)
- poly(d, l-lactic acid) (1)
- polyamide (1)
- polyester (1)
- portfolio risk (1)
- prevention (1)
- provenance (1)
- psychosocial (1)
- random effects (1)
- random effects meta-regression model (1)
- rehabilitation (1)
- reliability of structures (1)
- renewable resources (1)
- resource management (1)
- retinal microvasculature (1)
- retinal vessels (1)
- running (1)
- sEMG (1)
- sarcomere operating length (1)
- scanned light pulse technique (1)
- scheduling (1)
- security (1)
- sensors (1)
- separable Hilbert space (1)
- series elastic element behavior (1)
- shakedown analysis (1)
- shoulder (1)
- silanization (1)
- simulation (1)
- smooth muscle contraction (1)
- spatial resolution (1)
- sprint start (1)
- standard error of measurement (1)
- sterilisation (1)
- sterilization (1)
- sterilization conditions (1)
- stiffness (1)
- stochastic programming (1)
- strain energy function (1)
- stretch reflex (1)
- stretch-shortening cycle (1)
- superparamagnetic bead (1)
- superparamagnetic nanoparticles (1)
- surface functionalization (1)
- surface modification (1)
- survival (1)
- synchronization (1)
- temperature (1)
- tendon rupture (1)
- test-retest reliability (1)
- thermometry (1)
- tilted constant illumination (1)
- training simulator (1)
- tri-lineage differentiation (1)
- turnip vein clearing virus (TVCV) (1)
- twin-fluid atomizer (1)
- ultrasonography (1)
- uniformly most powerful invariant test (1)
- unloading (1)
- videolaryngoscopy (1)
- virgin passive (1)
- virtual reality (1)
- viscoelasticity (1)
- visualization (1)
- walking (1)
- walking gait (1)
- workflow (1)
- workflow management software (1)
In this work, a sensor to evaluate sterilization processes with hydrogen peroxide vapor has been characterized. Experimental, analytical and numerical methods were applied to evaluate and study the sensor behavior. The sensor set-up is based on planar interdigitated electrodes. The interdigitated electrode structure consists of 614 electrode fingers spanning over a total sensing area of 20 mm2. Sensor measurements were conducted with and without microbiological spores as well as after an industrial sterilization protocol. The measurements were verified using an analytical expression based on a first-order elliptical integral. A model based on the finite element method with periodic boundary conditions in two dimensions was developed and utilized to validate the experimental findings.
The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic sterilisation processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration experiment, taking into account the process variables H2O2 concentration, humidity and gas temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards the influencing factors of the sterilisation process have been analysed within the same experiment. Based on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates for monitoring the microbicidal effectiveness of aseptic sterilisation processes employing gaseous H2O2. Therefore, two linear models that describe the relationship between sensor response and microbicidal effectiveness have been proposed.
The light-addressable potentiometric sensor (LAPS) is an electrochemical sensor with a field-effect structure to detect the variation of the Nernst potential at its sensor surface, the measured area on which is defined by illumination. Thanks to this light-addressability, the LAPS can be applied to chemical imaging sensor systems, which can visualize the two-dimensional distribution of a particular target ion on the sensor surface. Chemical imaging sensor systems are expected to be useful for analysis of reaction and diffusion in various electrochemical and biological samples. Recent developments of LAPS-based chemical imaging sensor systems, in terms of the spatial resolution, measurement speed, image quality, miniaturization and integration with microfluidic devices, are summarized and discussed.
In this study we show an optical biosensor concept, based on elastic light scattering from sapphire microspheres. Transmitted and elastic scattering intensity of the microspheres (radius 500 μm, refractive index 1.77) on an optical fiber half coupler is analyzed at 1510 nm. The 0.43 nm angular mode spacing of the resonances is comparable to the angular mode spacing value estimated using the optical size of the microsphere. The spectral linewidths of the resonances are in the order of 0.01 nm, which corresponds to quality factors of approximately 105. A polydopamine layer is used as a functionalizing agent on sapphire microspherical resonators in view of biosensor implementation. The varying layer thickness on the microsphere is determined as a function of the resonance wavelength shift. It is shown that polymer functionalization has a minor effect on the quality factor. This is a promising step toward the development of an optical biosensor.
Detection of triacetone triperoxide using temperature cycled metal-oxide semiconductor gas sensors
(2015)
A new microfluidic assembly method for semiconductor-based biosensors using 3D-printing technologies was proposed for a rapid and cost-efficient design of new sensor systems. The microfluidic unit is designed and printed by a 3D-printer in just a few hours and assembled on a light-addressable potentiometric sensor (LAPS) chip using a photo resin. The cell growth curves obtained from culturing cells within microfluidics-based LAPS systems were compared with cell growth curves in cell culture flasks to examine biocompatibility of the 3D-printed chips. Furthermore, an optimal cell culturing within microfluidics-based LAPS chips was achieved by adjusting the fetal calf serum concentrations of the cell culture medium, an important factor for the cell proliferation.
The sterilization of packages in aseptic food processes is highly significant to maintain a consumer-safe product with extended shelf-life. Today, the sterilization of food packages is predominantly accomplished by gaseous hydrogen peroxide (H2O2) in combination with heat. In order to monitor this sterilization process, calorimetric gas sensors as differential set-up of two platinum temperature sensors representing a catalytically active (additionally deposition of MnO2) and a passive segment have been recently developed. The temperature rise of the exothermic decomposition serves as an indicator of the present H2O2 concentration. In the present work, a theoretical approach considering the sensor’s thermochemistry and physical transport phenomena was formulated to evaluate the temperature rise based on the energy content of gaseous H2O2. In a further part of this work, three polymers have been analyzed with respect to their application as passivation materials. The examined polymers are photoresist SU-8, perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP). Thermal analyses by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been conducted to determine the operation limits of the polymers. The overall chemical resistance and stability of the polymers against the harsh environmental conditions during the sterilization process have been examined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR).
Light-stimulated hydrogel actuators with incorporated graphene oxide for microfluidic applications
(2015)
The chemical imaging sensor was applied to in-situ pH imaging of the solution in the vicinity of a corroding surface of stainless steel under potentiostatic polarization. A test piece of polished stainless steel was placed on the sensing surface leaving a narrow gap filled with artificial seawater and the stainless steel was corroded under polarization. The pH images obtained during polarization showed correspondence between the region of lower pH and the site of corrosion. It was also found that the pH value in the gap became as low as 2 by polarization, which triggered corrosion.
This paper presents a numerical procedure for reliability analysis of thin plates and shells with respect to plastic collapse or to inadaptation. The procedure involves a deterministic shakedown analysis for each probabilistic iteration, which is based on the upper bound approach and the use of the exact Ilyushin yield surface. Probabilistic shakedown analysis deals with uncertainties originated from the loads, material strength and thickness of the shell. Based on a direct definition of the limit state function, the calculation of the failure probability may be efficiently solved by using the First and Second Order Reliability Methods (FORM and SORM). The problem of reliability of structural systems (series systems) is handled by the application of a special technique which permits to find all the design points corresponding to all the failure modes. Studies show, in this case, that it improves considerably the FORM and SORM results.
Booster stations can fulfill a varying pressure demand with high energy-efficiency, because individual pumps can be deactivated at smaller loads. Although this is a seemingly simple approach, it is not easy to decide precisely when to activate or deactivate pumps. Contemporary activation controls derive the switching points from the current volume flow through the system. However, it is not measured directly for various reasons. Instead, the controller estimates the flow based on other system properties. This causes further uncertainty for the switching decision. In this paper, we present a method to find a robust, yet energy-efficient activation strategy.
Changes in intestinal microflora in rats induced by oral exposure to low lead (II) concentrations
(2015)
We present an electromechanically coupled Finite Element model for cardiac tissue. It bases on the mechanical model for cardiac tissue of Hunter et al. that we couple to the McAllister-Noble-Tsien electrophysiological model of purkinje fibre cells. The corresponding system of ordinary differential equations is implemented on the level of the constitutive equations in a geometrically and physically nonlinear version of the so-called edge-based smoothed FEM for plates. Mechanical material parameters are determined from our own pressure-deflection experimental setup. The main purpose of the model is to further examine the experimental results not only on mechanical but also on electrophysiological level down to ion channel gates. Moreover, we present first drug treatment simulations and validate the model with respect to the experiments.
Capacitive field-effect electrolyte-insulator-semiconductor sensors consisting of an Al-p-Si-SiO2 structure have been used for the electrical detection of unlabelled single- and double-stranded DNA (dsDNA) molecules by their intrinsic charge. A simple functionalization protocol based on the layer-by-layer (LbL) technique was used to prepare a weak polyelectrolyte/probe-DNA bilayer, followed by the hybridization with complementary target DNA molecules. Due to the flat orientation of the LbL-adsorbed DNA molecules, a high sensor signal has been achieved. In addition, direct label-free detection of in-solution hybridized dsDNA molecules has been studied.
Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an electronic transduction of biochemical signals processed by enzyme-based AND-Reset and OR-Reset logic gates. The local pH change at the sensor surface induced by the enzymatic reaction was used for the activation of the Reset function for the first time.
A concept for a new generation of an integrated multi-functional biosensor/actuator system is developed, which is based on biomolecular logic principles. Such a system is expected to be able to detect multiple biochemical input signals simultaneously and in real-time and convert them into electrical output signals with logical operations such as OR, AND, etc. The system can be designed as a closed-loop drug release device triggered by an enzyme logic gate, while the release of the drug induced by the actuator at the required dosage and timing will be controlled by an additional drug sensor. Thus, the system could help to make an accurate and specific diagnosis. The presented concept is exemplarily demonstrated by using an enzyme logic gate based on a glucose/glucose oxidase system, a temperature-responsive hydrogel mimicking the actuator function and an insulin (drug) sensor. In this work, the results of functional testing of individual amperometric glucose and insulin sensors as well as an impedimetric sensor for the detection of the hydrogel swelling/shrinking are presented.
An amperometric enzyme biosensor has been applied for the detection of adrenaline. The adrenaline biosensor has been prepared by modification of an oxygen electrode with the enzyme laccase that operates at a broad pH range between pH 3.5 to pH 8. The enzyme molecules were immobilized via cross-linking with glutaraldehyde. The sensitivity of the developed adrenaline biosensor in different pH buffer solutions has been studied.
Label-free sensing of biomolecules by their intrinsic molecular charge using field-effect devices
(2015)
Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.
The characterization of the degradation kinetics of biodegradable polymers is mandatory with regard to their proper application. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) field-effect sensors have been applied for in-situ monitoring of the pH-dependent degradation kinetics of the commercially available biopolymer poly(d,l-lactic acid) (PDLLA) in buffer solutions from pH 3 to pH 13. PDLLA films of 500 nm thickness were deposited on the surface of an Al–p-Si–SiO2–Ta2O5 structure from a polymer solution by means of spin-coating method. The PMEIS sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. A faster degradation has been observed for PDLLA films exposed to alkaline solutions (pH 9, pH 11 and pH 13).
A sensor system for investigating (bio)degradationprocesses of polymers is presented. The system utilizes semiconductor field-effect sensors and is capable of monitoring the degradation process in-situ and in real-time. The degradation of the polymer poly(d,l-lactic acid) is exemplarily monitored in solutions with different pH value, pH-buffer solution containing the model enzyme lipase from Rhizomucormiehei and cell-culture medium containing supernatants from stimulated and non-stimulated THP-1-derived macrophages mimicking activation of the immune system.
Influence of refrigerated storage on tensile mechanical properties of porcine liver and spleen
(2015)
Miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge favor the semiconductor field-effect platform as one of the most attractive approaches for the development of label-free DNA chips. In this work, a capacitive field-effect EIS (electrolyte–insulator–semiconductor) sensor covered with a layer-by-layer prepared, positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was used for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization. The negatively charged probe single-stranded DNA (ssDNA) molecules were electrostatically adsorbed onto the positively charged PAH layer, resulting in a preferentially flat orientation of the ssDNA molecules within the Debye length, thus yielding a reduced charge-screening effect and a higher sensor signal. Each sensor-surface modification step (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), reducing an unspecific adsorption by a blocking agent, incubation with noncomplementary DNA (ncDNA) solution) was monitored by means of capacitance–voltage and constant-capacitance measurements. In addition, the surface morphology of the PAH layer was studied by atomic force microscopy and contact-angle measurements. High hybridization signals of 34 and 43 mV were recorded in low-ionic strength solutions of 10 and 1 mM, respectively. In contrast, a small signal of 4 mV was recorded in the case of unspecific adsorption of fully mismatched ncDNA. The density of probe ssDNA and dsDNA molecules as well as the hybridization efficiency was estimated using the experimentally measured DNA immobilization and hybridization signals and a simplified double-layer capacitor model. The results of field-effect experiments were supported by fluorescence measurements, verifying the DNA-immobilization and hybridization event.
A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent–voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout.
Data-driven prediction and prevention of extreme events in a spatially extended excitable system
(2015)
Let X₁,…,Xₙ be independent and identically distributed random variables with distribution F. Assuming that there are measurable functions f:R²→R and g:R²→R characterizing a family F of distributions on the Borel sets of R in the way that the random variables f(X₁,X₂),g(X₁,X₂) are independent, if and only if F∈F, we propose to treat the testing problem H:F∈F,K:F∉F by applying a consistent nonparametric independence test to the bivariate sample variables (f(Xᵢ,Xⱼ),g(Xᵢ,Xⱼ)),1⩽i,j⩽n,i≠j. A parametric bootstrap procedure needed to get critical values is shown to work. The consistency of the test is discussed. The power performance of the procedure is compared with that of the classical tests of Kolmogorov–Smirnov and Cramér–von Mises in the special cases where F is the family of gamma distributions or the family of inverse Gaussian distributions.
High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors. In this work, a Si-based sensor chip containing Pt interdigitated electrodes covered with a thin BST layer (485 nm) has been developed for multi-parameter chemical sensing. The chip has been applied for the contactless measurement of the electrolyte conductivity, the detection of adsorbed charged macromolecules (positively charged polyelectrolytes of polyethylenimine) and the concentration of hydrogen peroxide (H2O2) vapor. The experimental results of functional testing of individual sensors are presented. The mechanism of the BST sensitivity to charged polyelectrolytes and H2O2 vapor has been proposed and discussed.
Optimization of the immobilization of bacterial spores on glass substrates with organosilanes
(2016)
Spores can be immobilized on biosensors to function as sensitive recognition elements. However, the immobilization can affect the sensitivity and reproducibility of the sensor signal. In this work, three different immobilization strategies with organosilanes were optimized and characterized to immobilize Bacillus atrophaeus spores on glass substrates. Five different silanization parameters were investigated: nature of the solvent, concentration of the silane, silanization time, curing process, and silanization temperature. The resulting silane layers were resistant to a buffer solution (e.g., Ringer solution) with a polysorbate (e.g., Tween®80) and sonication.
Bonding of polymer-based microfluidics to polymer substrates still poses a challenge for Lab-On-a-Chip applications. Especially, when sensing elements are incorporated, patterned deposition of adhesives with curing at ambient conditions is required. Here, we demonstrate a fabrication method for fully printed microfluidic systems with sensing elements using inkjet and stereolithographic 3D-printing.
On-line monitoring of the metabolic activity of microorganisms involved in intermediate stages of biogas production plays an important role to avoid undesirable “down times” during the biogas production. In order to control this process, an on-chip differential measuring system based on the light-addressable potentiometric sensor (LAPS) principle combined with a 3D-printed multi-chamber structure has been realized. As a test microorganism, Escherichia coli K12 (E. coli K12) were used for cell-based measurements. Multi-chamber structures were developed to determine the metabolic activity of E. coli K12 in suspension for a different number of cells, responding to the addition of a constant or variable amount of glucose concentrations, enabling differential and simultaneous measurements.
Abstractauthoren Graphene oxide (GO) nanoparticles were incorporated in temperature-sensitive Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The nanoparticles increase the light absorption and convert light energy into heat efficiently. Thus, the hydrogels with GO can be stimulated spatially resolved by illumination as it was demonstrated by IR thermography. The temporal progression of the temperature maximum was detected for different concentrations of GO within the polymer network. Furthermore, the compatibility of PNIPAAm hydrogels with GO and cell cultures was investigated. For this purpose, culture medium was incubated with hydrogels containing GO and the viability and morphology of chinese hamster ovary (CHO) cells was examined after several days of culturing in presence of this medium.
Purpose
Two semi-empirical models were recently published, both making use of existing literature data, but each taking into account different physical phenomena that trigger hemolysis. In the first model, hemoglobin (Hb) release is described as a permeation procedure across the membrane, assuming a shear stress-dependent process (sublethal model). The second model only accounts for hemoglobin release that is caused by cell membrane breakdown, which occurs when red blood cells (RBC) undergo mechanically induced shearing for a period longer than the threshold time (nonuniform threshold model). In this paper, we introduce a model that considers the hemolysis generated by both these possible phenomena.
Methods
Since hemolysis can possibly be caused by permeation of hemoglobin through the RBC functional membrane as well as by release of hemoglobin from RBC membrane breakdown, our proposed model combines both these models. An experimental setup consisting of a Couette device was utilized for validation of our proposed model.
Results
A comparison is presented between the damage index (DI) predicted by the proposed model vs. the sublethal model vs. the nonthreshold model and experimental datasets. This comparison covers a wide range of shear stress for both human and porcine blood. An appropriate agreement between the measured DI and the DI predicted by the present model was obtained.
Conclusions
The semiempirical hemolysis model introduced in this paper aims for significantly enhanced conformity with experimental data. Two phenomenological outcomes become possible with the proposed approach: an estimation of the average time after which cell membrane breakdown occurs under the applied conditions, and a prediction of the ratio between the phenomena involved in hemolysis.
We investigate the suitability of selected measures of complexity based on recurrence quantification analysis and recurrence networks for an identification of pre-seizure states in multi-day, multi-channel, invasive electroencephalographic recordings from five epilepsy patients. We employ several statistical techniques to avoid spurious findings due to various influencing factors and due to multiple comparisons and observe precursory structures in three patients. Our findings indicate a high congruence among measures in identifying seizure precursors and emphasize the current notion of seizure generation in large-scale epileptic networks. A final judgment of the suitability for field studies, however, requires evaluation on a larger database.
Treatment of posttraumatic osteoarthritis of the radial column of the elbow joint remains a challenging yet common issue.
While partial joint replacement leads to high revision rates, radial head excision has shown to severely increase joint instability. Shortening osteotomy of the radius could be an option to decrease the contact pressure of the radiohumeral joint and thereby pain levels without causing valgus instability. Hence, the aim of this biomechanical study was to evaluate the effects of radial shortening on axial load distribution and valgus stability of the elbow joint.
Purpose
The most commonly used mobility assessments for screening risk of falls among older adults are rating scales such as the Tinetti performance oriented mobility assessment (POMA). However, its correlation with falls is not always predictable and disadvantages of the scale include difficulty to assess many of the items on a 3-point scale and poor specificity. The purpose of this study was to describe the ability of the new Aachen Mobility and Balance Index (AMBI) to discriminate between subjects with a fall history and subjects without such events in comparison to the Tinetti POMA Scale.
Methods
For this prospective cohort study, 24 participants in the study group and 10 in the control group were selected from a population of patients in our hospital who had met the stringent inclusion criteria. Both groups completed the Tinetti POMA Scale (gait and balance component) and the AMBI (tandem stance, tandem walk, ten-meter-walk-test, sit-to-stand with five repetitions, 360° turns, timed-up-and-go-test and measurement of the dominant hand grip strength). A history of falls and hospitalization in the past year were evaluated retrospectively. The relationships among the mobility tests were examined with Bland–Altmananalysis. Receiver-operated characteristics curves, sensitivity and specificity were calculated.
Results
The study showed a strong negative correlation between the AMBI (17 points max., highest fall risk) and Tinetti POMA Scale (28 points max., lowest fall risk; r = −0.78, p < 0.001) with an excellent discrimination between community-dwelling older people and a younger control group. However, there were no differences in any of the mobility and balance measurements between participants with and without a fall history with equal characteristics in test comparison (AMBI vs. Tinetti POMA Scale: AUC 0.570 vs. 0.598; p = 0.762). The Tinetti POMA Scale (cut-off <20 points) showed a sensitivity of 0.45 and a specificity of 0.69, the AMBI a sensitivity of 0.64 and a specificity of 0.46 (cut-off >5 points).
Conclusion
The AMBI comprises mobility and balance tasks with increasing difficulty as well as a measurement of the dominant hand-grip strength. Its ability to identify fallers was comparable to the Tinetti POMA Scale. However, both measurement sets showed shortcomings in discrimination between fallers and non-fallers based on a self-reported retrospective falls-status.
The light-addressable potentiometric sensor (LAPS) has the unique feature to address different regions of a sensor surface without the need of complex structures. Measurements at different locations on the sensor surface can be performed in a common analyte solution, which distinctly simplifies the fluidic set-up. However, the measurement in a single analyte chamber prevents the application of different drugs or different concentrations of a drug to each measurement spot at the same time as in the case of multi-reservoir-based set-ups. In this work, the authors designed a LAPS-based set-up for cell culture screening that utilises magnetic beads loaded with the endotoxin (lipopolysaccharides, LPS), to generate a spatially distributed gradient of analyte concentration. Different external magnetic fields can be adjusted to move the magnetic beads loaded with a specific drug within the measurement cell. By recording the metabolic activities of a cell layer cultured on top of the LAPS surface, this work shows the possibility to apply different concentrations of a sample along the LAPS measurement spots within a common analyte solution.
Light-addressable potentiometric sensor as a sensing element in plug-based microfluidic devices
(2016)
A plug-based microfluidic system based on the principle of the light-addressable potentiometric sensor (LAPS) is proposed. The LAPS is a semiconductor-based chemical sensor, which has a free addressability of the measurement point on the sensing surface. By combining a microfluidic device and LAPS, ion sensing can be performed anywhere inside the microfluidic channel. In this study, the sample solution to be measured was introduced into the channel in a form of a plug with a volume in the range of microliters. Taking advantage of the light-addressability, the position of the plug could be monitored and pneumatically controlled. With the developed system, the pH value of a plug with a volume down to 400 nL could be measured. As an example of plug-based operation, two plugs were merged in the channel, and the pH change was detected by differential measurement.
The enormous diversity of seed traits is an intriguing feature and critical for the overwhelming success of higher plants. In particular, seed mass is generally regarded to be key for seedling development but is mostly approximated by using scanning methods delivering only two-dimensional data, often termed seed size. However, three-dimensional traits, such as the volume or mass of single seeds, are very rarely determined in routine measurements. Here, we introduce a device named phenoSeeder, which enables the handling and phenotyping of individual seeds of very different sizes. The system consists of a pick-and-place robot and a modular setup of sensors that can be versatilely extended. Basic biometric traits detected for individual seeds are two-dimensional data from projections, three-dimensional data from volumetric measures, and mass, from which seed density is also calculated. Each seed is tracked by an identifier and, after phenotyping, can be planted, sorted, or individually stored for further evaluation or processing (e.g. in routine seed-to-plant tracking pipelines). By investigating seeds of Arabidopsis (Arabidopsis thaliana), rapeseed (Brassica napus), and barley (Hordeum vulgare), we observed that, even for apparently round-shaped seeds of rapeseed, correlations between the projected area and the mass of seeds were much weaker than between volume and mass. This indicates that simple projections may not deliver good proxies for seed mass. Although throughput is limited, we expect that automated seed phenotyping on a single-seed basis can contribute valuable information for applications in a wide range of wild or crop species, including seed classification, seed sorting, and assessment of seed quality.
The stimulation and dominance of potentially harmful phytoplankton taxa at a given locale and time are determined by local environmental conditions as well as by transport to or from neighboring regions. The present study investigated the occurrence of common harmful algal bloom (HAB) taxa within the Southern California Bight, using cross-correlation functions to determine potential dependencies between HAB taxa and environmental factors, and potential links to algal transport via local hydrography and currents. A simulation study, in which Lagrangian particles were released, was used to assess travel times due to advection by prevailing ocean currents in the bight. Our results indicate that transport of some taxa may be an important mechanism for the expansion of their distributions into other regions, which was supported by mean travel times derived from our simulation study and other literature on ocean currents in the Southern California Bight. In other cases, however, phytoplankton dynamics were rather linked to local environmental conditions, including coastal upwelling events. Overall, our study shows that complex current patterns in the Southern California Bight may contribute significantly to the formation and expansion of HABs in addition to local environmental factors determining the spatiotemporal dynamics of phytoplankton blooms.
At the present time, one of the most serious environmental problems of Central Asia and South Kazakhstan is the ongoing large-scale deterioration of principal urban tree populations. Several major centers of massive spread of invasive plant pests have been found in urban dendroflora of this region. The degree of damage of seven most wide-spread aboriginal tree species was found to range from 21.4±1.1 to 85.4±1.8%. In particular, the integrity of the native communities of sycamore (Platanus spp.), willow (Salix spp.), poplar (Populus spp.) and elm (Ulmus spp.) is highly endangered. Our taxonomic analysis of the most dangerous tree pests of the region has revealed them as neobiontic xylophilous insects such as Cossus cossus L. (Order: Lepidoptera L.) Monochamus urussovi Fisch., Monochamus sutor L., Acanthocinus aedelis L. and Ñetonia aureate L. (Order: Coleoptera L.). We relate the origin of this threatening trend with the import of industrial wood in the mid 90s of the last century that was associated with high degree of the constructional work in the region. Because of the absence of efficient natural predators of the pest species, the application of microbiological methods of the pest control and limitation is suggested.
Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.
While plate fixation of proximal ulna fractures might lead to superior clinical results compared to tension band wiring, regular plates represent an established risk factor for wound complications. The olecranon double plates (Medartis, Basel, CH) might decrease complications related to the osteosynthesis because of their low profile and better anatomical fit. This study aimed to evaluate the biomechanical performance and clinical results of the olecranon double plates.
A New Class of Biosensors Based on Tobacco Mosaic Virus and Coat Proteins as Enzyme Nanocarrier
(2016)
An amperometric biosensor using a substrate recycling principle was realized for the detection of low adrenaline concentrations (1 nM) by measurements in phosphate buffer and Ringer’s solution at pH 6.5 and pH 7.4, respectively. In proof-of-concept experiments, a Boolean logic-gate principle has been applied to develop a digital adrenaline biosensor based on an enzyme AND logic gate. The obtained results demonstrate that the developed digital biosensor is capable for a rapid qualitative determination of the presence/absence of adrenaline in a YES/NO statement. Such digital biosensor could be used in clinical diagnostics for the control of a correct insertion of a catheter in the adrenal veins during adrenal venous-sampling procedure.
Label-free Electrostatic Detection of DNA Amplification by PCR Using Capacitive Field-effect Devices
(2016)
A capacitive field-effect EIS (electrolyte-insulator-semiconductor) sensor modified with a positively charged weak polyelectrolyte of poly(allylamine hydrochloride) (PAH)/single-stranded probe DNA (ssDNA) bilayer has been used for a label-free electrostatic detection of pathogen-specific DNA amplification via polymerase chain reaction (PCR). The sensor is able to distinguish between positive and negative PCR solutions, to detect the existence of target DNA amplicons in PCR samples and thus, can be used as tool for a quick verification of DNA amplification and the successful PCR process.
A multi-spot light-addressable potentiometric sensor (LAPS), which belongs to the family of semiconductor field-effect devices, was applied for label-free detection of double-stranded deoxyribonucleic acid (dsDNA) molecules by their intrinsic molecular charge. To reduce the distance between the DNA charge and sensor surface and thus, to enhance the electrostatic coupling between the dsDNA molecules and the LAPS, the negatively charged dsDNA molecules were electrostatically adsorbed onto the gate surface of the LAPS covered with a positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)). The surface potential changes in each spot of the LAPS, induced by the layer-by-layer adsorption of a PAH/dsDNA bilayer, were recorded by means of photocurrent-voltage and constant-photocurrent measurements. In addition, the surface morphology of the gate surface before and after consecutive electrostatic adsorption of PAH and dsDNA layers was studied by atomic force microscopy measurements. Moreover, fluorescence microscopy was used to verify the successful adsorption of dsDNA molecules onto the PAH-modified LAPS surface. A high sensor signal of 25 mV was registered after adsorption of 10 nM dsDNA molecules. The lower detection limit is down to 0.1 nM dsDNA. The obtained results demonstrate that the PAH-modified LAPS device provides a convenient and rapid platform for the direct label-free electrical detection of in-solution hybridized dsDNA molecules.
Analysis of the long-term effect of the MBST® nuclear magnetic resonance therapy on gonarthrosis
(2016)
The structure of the female pelvic floor (PF) is an inter-related system of bony pelvis,muscles, pelvic organs, fascias, ligaments, and nerves with multiple functions. Mechanically, thepelvic organ support system are of two types: (I) supporting system of the levator ani (LA) muscle,and (II) the suspension system of the endopelvic fascia condensation [1], [2]. Significantdenervation injury to the pelvic musculature, depolimerization of the collagen fibrils of the softvaginal hammock, cervical ring and ligaments during pregnancy and vaginal delivery weakens thenormal functions of the pelvic floor. Pelvic organ prolapse, incontinence, sexual dysfunction aresome of the dysfunctions which increases progressively with age and menopause due toweakened support system according to the Integral theory [3]. An improved 3D finite elementmodel of the female pelvic floor as shown in Fig. 1 is constructed that: (I) considers the realisticsupport of the organs to the pelvic side walls, (II) employs the improvement of our previous FEmodel [4], [5] along with the patient based geometries, (III) incorporates the realistic anatomy andboundary conditions of the endopelvic (pubocervical and rectovaginal) fascia, and (IV) considersvarying stiffness of the endopelvic fascia in the craniocaudal direction [3]. Several computationsare carried out on the presented computational model with healthy and damaged supportingtissues, and comparisons are made to understand the physiopathology of the female PF disorders.
The human arm consists of the humerus (upper arm), the medial ulna and the lateral radius (forearm). The joint between the humerus and the ulna is called humeroulnar joint and the joint between the humerus and the radius is called humeroradial joint. Lateral and medial collateral ligaments stabilize the elbow. Statistically, 2.5 out of 10,000 people suffer from radial head fractures [1]. In these fractures the cartilage is often affected. Caused by the injured cartilage, degenerative diseases like posttraumatic arthrosis may occur. The resulting pain and reduced range of motion have an impact on the patient’s quality of life. Until now, there has not been a treatment which allows typical loads in daily life activities and offers good long-term results. A new surgical approach was developed with the motivation to reduce the progress of the posttraumatic arthrosis. Here, the radius is shortened by 3 mm in the proximal part [2]. By this means, the load of the radius is intended to be reduced due to a load shift to the ulna. Since the radius is the most important stabilizer of the elbow it has to be confirmed that the stability is not affected. In the first test (Fig. 1 left), pressure distributions within the humeroulnar and humeroradial joints a native and a shortened radius were measured using resistive pressure sensors (I5076 and I5027, Tekscan, USA). The humerus was loaded axially in a tension testing machine (Z010, Zwick Roell, Germany) in 50 N steps up to 400 N. From the humerus the load is transmitted through both the radius and the ulna into the hand which is fixed on the ground. In the second test (Fig. 1 right), the joint stability was investigated using a digital image correlation system to measure the displacement of the ulna. Here, the humerus is fixed with a desired flexion angle and the unconstrained forearm lies on the ground. A rope connects the load actuator with a hook fixed in the ulna. A guide roller is used so that the rope pulls the ulna horizontally when a tensile load is applied. This creates a moment about the elbow joint with a maximum value of 7.5 Nm. Measurements were performed with varying flexion angles (0°, 30°, 60°, 90°, 120°). For both tests and each measurement, seven specimens were used. Student ́s t-test was employed to determine whether the mean values of the measurements in native specimen and operated specimens differ significantly.
Plate osteosynthesis of displaced proximal phalangeal neck fractures of the hand allows early mobilization due to a stable internal fixation. Nevertheless, joint stiffness—because of soft tissue irritation—represents a common complication leading to high complication rates. Del Pinal et al. recently reported promising clinical results for a new, minimally invasive fixation technique with a cannulated headless intramedullary compression screw. Hence, the aim of this study was to compare plate fixation of proximal phalangeal neck fractures to less two less invasive techniques: Crossed k-wire fixation and intramedullary screw fixation. We hypothesized that these fixation techniques provide inferior stability when compared to plate osteosynthesis.
L.setulosus is offered for creation of biopreparation «Setulin», possesing he- mostatic action, the basic reactant of biopreparation is diterpen – lagochirzin. Results under the maintenance and dynamics of diterpen lagochirzin accumula- tion in various parts of L.setulosus are presented: in roots, stalks, leaves, flowers and calyx lobes during the growing season, and also results on conditions of cultivation L.setulosus in the conditions of a typical sierozem are resulted. From the obtained data is visible, that the given species of a plant is endemic. It is established, that dynamics of accumulation of lagochirzin in phytomass accrues from the beginning to the middle of the growing season. The chemical analysis of L.setulosus on a localization of lagochirzin in various organs of a plant, has shown, that the greatest quantity of lagochirzin collects in calyx lobes of the plants. Also it is established, that L.setulosus can be cultivated in the conditions of the typical sierozem, a mineral food is necessary for the given species of plants of Lagochilus genus, except nitric fertilizers. Comparative studying of wild-growing and cultural forms of L.setulosus has shown, that in the cultivated phytomass of plants the maintenance of lagochirzin on 17-20 % higher than in the wild-growing species.
Based on an identifying Volterra type integral equation for randomly right censored observations from a lifetime distribution function F, we solve the corresponding estimating equation by an explicit and implicit Euler scheme. While the first approach results in some known estimators, the second one produces new semi-parametric and pre-smoothed Kaplan–Meier estimators which are real distribution functions rather than sub-distribution functions as the former ones are. This property of the new estimators is particular useful if one wants to estimate the expected lifetime restricted to the support of the observation time.
Specifically, we focus on estimation under the semi-parametric random censorship model (SRCM), that is, a random censorship model where the conditional expectation of the censoring indicator given the observation belongs to a parametric family. We show that some estimated linear functionals which are based on the new semi-parametric estimator are strong consistent, asymptotically normal, and efficient under SRCM. In a small simulation study, the performance of the new estimator is illustrated under moderate sample sizes. Finally, we apply the new estimator to a well-known real dataset.
We present an electromechanically coupled computational model for the investigation of a thin cardiac tissue construct consisting of human-induced pluripotent stem cell-derived atrial, ventricular and sinoatrial cardiomyocytes. The mechanical and electrophysiological parts of the finite element model, as well as their coupling are explained in detail. The model is implemented in the open source finite element code Code_Aster and is employed for the simulation of a thin circular membrane deflected by a monolayer of autonomously beating, circular, thin cardiac tissue. Two cardio-active drugs, S-Bay K8644 and veratridine, are applied in experiments and simulations and are investigated with respect to their chronotropic effects on the tissue. These results demonstrate the potential of coupled micro- and macroscopic electromechanical models of cardiac tissue to be adapted to experimental results at the cellular level. Further model improvements are discussed taking into account experimentally measurable quantities that can easily be extracted from the obtained experimental results. The goal is to estimate the potential to adapt the presented model to sample specific cell cultures.
Background/Aims: Common systems for the quantification of cellular contraction rely on animal-based models, complex experimental setups or indirect approaches. The herein presented CellDrum technology for testing mechanical tension of cellular monolayers and thin tissue constructs has the potential to scale-up mechanical testing towards medium-throughput analyses. Using hiPS-Cardiac Myocytes (hiPS-CMs) it represents a new perspective of drug testing and brings us closer to personalized drug medication. Methods: In the present study, monolayers of self-beating hiPS-CMs were grown on ultra-thin circular silicone membranes and deflect under the weight of the culture medium. Rhythmic contractions of the hiPS-CMs induced variations of the membrane deflection. The recorded contraction-relaxation-cycles were analyzed with respect to their amplitudes, durations, time integrals and frequencies. Besides unstimulated force and tensile stress, we investigated the effects of agonists and antagonists acting on Ca²⁺ channels (S-Bay K8644/verapamil) and Na⁺ channels (veratridine/lidocaine). Results: The measured data and simulations for pharmacologically unstimulated contraction resembled findings in native human heart tissue, while the pharmacological dose-response curves were highly accurate and consistent with reference data. Conclusion: We conclude that the combination of the CellDrum with hiPS-CMs offers a fast, facile and precise system for pharmacological, toxicological studies and offers new preclinical basic research potential.
Retinal Vessel Analysis (RVA) in the context of subarachnoid hemorrhage: A proof of concept study
(2016)
Background
Timely detection of impending delayed cerebral ischemia after subarachnoid hemorrhage (SAH) is essential to improve outcome, but poses a diagnostic challenge. Retinal vessels as an embryological part of the intracranial vasculature are easily accessible for analysis and may hold the key to a new and non-invasive monitoring technique. This investigation aims to determine the feasibility of standardized retinal vessel analysis (RVA) in the context of SAH.
Methods
In a prospective pilot study, we performed RVA in six patients awake and cooperative with SAH in the acute phase (day 2–14) and eight patients at the time of follow-up (mean 4.6±1.7months after SAH), and included 33 age-matched healthy controls. Data was acquired using a manoeuvrable Dynamic Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and neurovascular coupling.
Results
Image quality was satisfactory in the majority of cases (93.3%). In the acute phase after SAH, retinal arteries were significantly dilated when compared to the control group (124.2±4.3MU vs 110.9±11.4MU, p<0.01), a difference that persisted to a lesser extent in the later stage of the disease (122.7±17.2MU, p<0.05). Testing for neurovascular coupling showed a trend towards impaired primary vasodilation and secondary vasoconstriction (p = 0.08, p = 0.09 resp.) initially and partial recovery at the time of follow-up, indicating a relative improvement in a time-dependent fashion.
Conclusion
RVA is technically feasible in patients with SAH and can detect fluctuations in vessel diameter and autoregulation even in less severely affected patients. Preliminary data suggests potential for RVA as a new and non-invasive tool for advanced SAH monitoring, but clinical relevance and prognostic value will have to be determined in a larger cohort.
In this study, we show that synthetic sapphire (Al₂O₃), an established implant material, can also serve as a platform material for biosensors comparable to nanocrystalline diamond. Sapphire chips, beads, and powder were first modified with (3-aminopropyl) triethoxysilane (APTES), followed by succinic anhydride (SA), and finally single-stranded probe DNA was EDC coupled to the functionalized layer. The presence of the APTES-SA layer on sapphire powders was confirmed by thermogravimetric analyis and Fourier-transform infrared spectroscopy. Using planar sapphire chips as substrates and X-ray photoelectron spectroscopy (XPS) as surface-sensitive tool, the sequence of individual layers was analyzed with respect to their chemical state, enabling the quantification of areal densities of the involved molecular units. Fluorescence microscopy was used to demonstrate the hybridization of fluorescently tagged target DNA to the probe DNA, including denaturation- and re-hybridization experiments. Due to its high thermal conductivity, synthetic sapphire is especially suitable as a chip material for the heat-transfer method, which was employed to distinguish complementary- and non-complementary DNA duplexes containing single-nucleotide polymorphisms. These results indicate that it is possible to detect mutations electronically with a chemically resilient and electrically insulating chip material.
Background and Objective
Effective leg extension training at a leg press requires high forces, which need to be controlled to avoid training-induced damage. In order to avoid high external knee adduction moments, which are one reason for unphysiological loadings on knee joint structures, both training movements and the whole reaction force vector need to be observed. In this study, the applicability of lateral and medial changes in foot orientation and position as possible manipulated variables to control external knee adduction moments is investigated. As secondary parameters both the medio-lateral position of the center of pressure and the frontal-plane orientation of the reaction force vector are analyzed.
Methods
Knee adduction moments are estimated using a dynamic model of the musculoskeletal system together with the measured reaction force vector and the motion of the subject by solving the inverse kinematic and dynamic problem. Six different foot conditions with varying positions and orientations of the foot in a static leg press are evaluated and compared to a neutral foot position.
Results
Both lateral and medial wedges under the foot and medial and lateral shifts of the foot can influence external knee adduction moments in the presented study with six healthy subjects. Different effects are observed with the varying conditions: the pose of the leg is changed and the direction and center of pressure of the reaction force vector is influenced. Each effect results in a different direction or center of pressure of the reaction force vector.
Conclusions
The results allow the conclusion that foot position and orientation can be used as manipulated variables in a control loop to actively control knee adduction moments in leg extension training.
To better understand what kinds of sports and exercise could be beneficial for the intervertebral disc (IVD), we performed a review to synthesise the literature on IVD adaptation with loading and exercise. The state of the literature did not permit a systematic review; therefore, we performed a narrative review. The majority of the available data come from cell or whole-disc loading models and animal exercise models. However, some studies have examined the impact of specific sports on IVD degeneration in humans and acute exercise on disc size. Based on the data available in the literature, loading types that are likely beneficial to the IVD are dynamic, axial, at slow to moderate movement speeds, and of a magnitude experienced in walking and jogging. Static loading, torsional loading, flexion with compression, rapid loading, high-impact loading and explosive tasks are likely detrimental for the IVD. Reduced physical activity and disuse appear to be detrimental for the IVD. We also consider the impact of genetics and the likelihood of a ‘critical period’ for the effect of exercise in IVD development. The current review summarises the literature to increase awareness amongst exercise, rehabilitation and ergonomic professionals regarding IVD health and provides recommendations on future directions in research.
The Saturnian moon Enceladus with its extensive water bodies underneath a thick ice sheet cover is a potential candidate for extraterrestrial life. Direct exploration of such extraterrestrial aquatic ecosystems requires advanced access and sampling technologies with a high level of autonomy. A new technological approach has been developed as part of the collaborative research project Enceladus Explorer (EnEx). The concept is based upon a minimally invasive melting probe called the IceMole. The force-regulated, heater-controlled IceMole is able to travel along a curved trajectory as well as upwards. Hence, it allows maneuvers which may be necessary for obstacle avoidance or target selection. Maneuverability, however, necessitates a sophisticated on-board navigation system capable of autonomous operations. The development of such a navigational system has been the focal part of the EnEx project. The original IceMole has been further developed to include relative positioning based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection integrated through a high-level sensor fusion. This paper describes the EnEx technology and discusses implications for an actual extraterrestrial mission concept.
In this paper we propose a stochastic programming method to analyse limit and shakedown of structures under uncertainty condition of strength. Based on the duality theory, the shakedown load multiplier formulated by the kinematic theorem is proved actually to be the dual form of the shakedown load multiplier formulated by static theorem. In this investigation a dual chance constrained programming algorithm is developed to calculate simultaneously both the upper and lower bounds of the plastic collapse limit and the shakedown limit. The edge-based smoothed finite element method (ES-FEM) with three-node linear triangular elements is used for structural analysis.
Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species
(2017)
A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed.
The capacitive electrolyte–insulator–semiconductor (EIS) structure is a typical device based on a field-effect sensor platform. With a simple silicon-based structure, EIS have been useful for several sensing applications, especially with incorporation of nanostructured films to modulate the ionic transport and the flat-band potential. In this paper, we report on ion transport and changes in flat-band potential in EIS sensors made with layer-by-layer films containing poly(amidoamine) (PAMAM) dendrimer and single-walled carbon nanotubes (SWNTs) adsorbed on p-Si/SiO 2 /Ta 2 O 5 chips with an Al ohmic contact. The impedance spectra were fitted using an equivalent circuit model, from which we could determine parameters such as the double-layer capacitance. This capacitance decreased with the number of bilayers owing to space charge accumulated at the electrolyte–insulator interface, up to three PAMAM/SWNTs bilayers, after which it stabilized. The charge-transfer resistance was also minimum for three bilayers, thus indicating that this is the ideal architecture for an optimized EIS performance. The understanding of the influence of nanostructures and the fine control of operation parameters pave the way for optimizing the design and performance of new EIS sensors.