Article
Refine
Year of publication
Institute
- IfB - Institut für Bioengineering (450) (remove)
Document Type
- Article (450) (remove)
Keywords
- CellDrum (3)
- Einspielen <Werkstoff> (3)
- Lipopolysaccharide (2)
- Stiffness (2)
- bacterial cellulose (2)
- carbonized rice husk (2)
- damage (2)
- locomotion (2)
- muscle fascicle behavior (2)
- prebiotic (2)
- shakedown analysis (2)
- ultrasound (2)
- ultrasound imaging (2)
- Achilles tendon (1)
- Adaptive control (1)
- Ageing (1)
- Air purification (1)
- AlterG (1)
- Alternating plasticity (1)
- Alzheimer's disease (1)
- Analysis (1)
- Analytischer Zulaessigkeitsnachweis (1)
- Anastomotic leakage (1)
- Anatomy (1)
- Annulus Fibrosus (1)
- Antarctic Glaciology (1)
- Architectural gear ratio (1)
- Arthosetherapie (1)
- Assistive technology (1)
- Aufschlagversuch (1)
- Autolysis (1)
- Automatic control (1)
- Axialbelastung (1)
- Axially cracked pipe (1)
- Bacillus sp (1)
- Bacterial cellulose (1)
- Biocomposites (1)
- Biomechanical simulation (1)
- Bioreaktor (1)
- Biosolubilization (1)
- Blutzellenlagerung (1)
- Bone quality and biomechanics (1)
- Carbon sources (1)
- Cardiac myocytes (1)
- Cardiac tissue (1)
- Cell permeability (1)
- Cellular force (1)
- Cellulose nanostructure (1)
- Cement infiltration (1)
- Cementoblast (1)
- Circular Dichroism (1)
- Clusterion (1)
- Coal (1)
- Compression (1)
- Computational biomechanics (1)
- Constitutive model (1)
- Contractile tension (1)
- Cost-effectiveness (1)
- Culture media (1)
- DLR-ESTEC GOSSAMER roadmap for solar sailing (1)
- Damage mechanics theory (1)
- Decomposition (1)
- Deformation (1)
- Design-by-analysis (1)
- Disc Degeneration (1)
- Discontinuous fractures (1)
- Distorsion des oberen Sprunggelenks (1)
- Druckbeanspruchung (1)
- Druckbehälter (1)
- Druckbelastung (1)
- Drug simulation (1)
- ES-FEM (1)
- Einspiel-Analyse (1)
- Einspiel-Kriterium (1)
- Einspielen (1)
- Electromechanical modeling (1)
- End-to-end colorectal anastomosis (1)
- Endothelial cells (1)
- Endothelial dysfunction (1)
- Environmental impact (1)
- Epithel (1)
- Experiment (1)
- External knee adduction moments (1)
- Extraterrestrial Glaciology (1)
- FEM (1)
- FS-FEM (1)
- Fehlerstellen (1)
- Fibroblast (1)
- Finite element analysis (1)
- Finite element modelling (1)
- Finite-Elemente-Methode (1)
- Fließgrenze (1)
- Forces (1)
- Fracture configuration (1)
- Fracture simulation (1)
- Freeze–thaw process (1)
- Frequency adaption (1)
- Fußball (1)
- GOSSAMER-1 (1)
- Geriatric (1)
- Glaciological instruments and methods (1)
- Glaucoma (1)
- Global and local collapse (1)
- Gonarthrose (1)
- Grenzwertberechnung (1)
- H2 (1)
- Haemodialysis (1)
- Handbike (1)
- Harnleiter (1)
- Heart tissue culture (1)
- Hemoglobin structure (1)
- Hip fractures (1)
- Hodgkin–Huxley models (1)
- Homogenization (1)
- Human-Computer interaction (1)
- Hydrogenotrophic methanogens (1)
- Hämoglobin (1)
- Hämoglobinstruktur (1)
- Induced pluripotent stem cells (1)
- Inotropic compounds (1)
- Interstellar objects (1)
- Intervertebral Disc (1)
- Intradiscal Pressure (1)
- Inverse dynamic problem (1)
- Inverse kinematic problem (1)
- Ion channels (1)
- Iterative learning control (1)
- Kniegelenkarthrose (1)
- Knochen (1)
- Knochenbildung (1)
- Knochenchirugie (1)
- Knochendichte (1)
- Kohlenstofffaser (1)
- LPS (1)
- Lactobacillus rhamnosus GG (1)
- Limit analysis (1)
- Liver (1)
- Long COVID (1)
- Luftreiniger (1)
- MBST (1)
- Machine learning (1)
- Manipulated variables (1)
- Mechanotransduction (1)
- Medusomyces gisevi (1)
- Methane (1)
- Methanogenesis (1)
- Microcirculation (1)
- Mild cognitive impairment (1)
- Missions (1)
- Muscle (1)
- Muscle Fascicle (1)
- Muscle Force (1)
- Musculoskeletal model (1)
- Musculoskeletal system (1)
- Myocardial infarction and cardiac death (1)
- NONOate (1)
- Natural fibres (1)
- Nitric Oxide (1)
- Nitric Oxide Donor (1)
- Non-parallel fissures (1)
- Nucleus Pulposus (1)
- Ocular blood flow (1)
- Organkultur (1)
- Osteoporose (1)
- Osteoporosis (1)
- Paralympic sport (1)
- Permeability (1)
- Permeabilität (1)
- Pflanzenphysiologie (1)
- Pflanzenscanner (1)
- Pflanzenstress (1)
- Pharmacology (1)
- Physiology (1)
- Plasmacluster ion technology (1)
- Plastizität (1)
- Polymer-matrix composites (1)
- Post-COVID-19 syndrome (1)
- Pressure loaded crack-face (1)
- Prevention (1)
- Progressive plastic deformation (1)
- Prophylaxis (1)
- Proximal humerus fracture (1)
- Pulsations (1)
- RVA (1)
- Ratchetting (1)
- Raumluft (1)
- Recombinant activated protein C (1)
- Red blood cell storage (1)
- Rehabilitation Technology and Prosthetics (1)
- Rehabilitation engineering (1)
- Retinal vessel analysis (1)
- Retinal vessels (1)
- Robotic rehabilitation (1)
- Rohr (1)
- Rohrbruch (1)
- Rotator cuff (1)
- Running (1)
- S-FEM (1)
- Schienbeinschoner (1)
- Schwammknochen (1)
- Septic cardiomyopathy (1)
- Shakedown (1)
- Shakedown analysis (1)
- Shakedown criterion (1)
- Simulation (1)
- Skeletal muscle (1)
- Small Aral Sea (1)
- Small spacecraft (1)
- Solar sail (1)
- Spleen (1)
- Sprunggelenkorthesen (1)
- Stahl (1)
- Stress concentrations (1)
- Strukturanalyse (1)
- Subclacial exploration (1)
- Subglacial lakes (1)
- SunRav BookEditor (1)
- Surgical Navigation and Robotics (1)
- Surgical staplers (1)
- Temperaturabhängigkeit (1)
- Tendon Rupture (1)
- Tendon properties (1)
- Tendons (1)
- Tension (1)
- Tissue Engineering (1)
- Traglastanalyse (1)
- Trajectories (1)
- Ultrasound (1)
- Uniaxial compression test (1)
- Variable height stapler design (1)
- Vascular response (1)
- Vasomotions (1)
- Vertebroplastie (1)
- Vertebroplasty (1)
- Viscous flow (1)
- Viskose Strömung (1)
- Viskosität (1)
- Visual field asymmetry (1)
- Wolff's Law (1)
- Wolffsches Gesetz (1)
- Wundheilung (1)
- Zug-Druck Belastung (1)
- achilles tendon (1)
- actin cytoskeleton (1)
- adipose-derived stromal cells (ASCs) (1)
- adsorption (1)
- agility (1)
- alternierend Verformbarkeit (1)
- anaesthetic complications (1)
- anisotropy (1)
- ankle braces (1)
- ankle sprain (1)
- aortic perfusion (1)
- arthrosis therapy (1)
- biaxial tensile experiment (1)
- biofilms (1)
- biomechanics (1)
- biopotential electrodes (1)
- bone density (1)
- bone structure (1)
- burst pressure (1)
- burst tests (1)
- cancellous bone (1)
- cardiomyocyte biomechanics (1)
- cell aerosolization (1)
- cell atomization (1)
- cerebral small vessel disease (1)
- chance constrained programming (1)
- coculture (1)
- cognitive impairment (1)
- community dwelling (1)
- computational fluid dynamics analysis (1)
- connective tissue (1)
- constitutive modeling (1)
- constructive alignment (1)
- correlation (1)
- crop yield (1)
- dental trauma (1)
- dialysis (1)
- difficult airway (1)
- distance learning (1)
- distorted element (1)
- double-lumen tube intubation (1)
- drop jump (1)
- e-books (1)
- e-issues (1)
- ecological structure (1)
- electromyography (1)
- endoluminal (1)
- energy absorption (1)
- energy dissipation (1)
- epithelization (1)
- examination (1)
- exopolysaccharides (1)
- extracorporeal membrane oxygenation (1)
- fibulare Bandruptur (1)
- flaw (1)
- force generation (1)
- forehead EEG (1)
- fortschreitende plastische Deformation (1)
- gait (1)
- gonarthrosis (1)
- healthy aging (1)
- hiPS cardiomyocytes (1)
- high-intensity exercise (1)
- human dermal fibroblasts (1)
- humic acid (1)
- hyper-gravity (1)
- hyperelastic (1)
- hypo-gravity (1)
- immobilization (1)
- impedance spectroscopy (1)
- in-ear EEG (1)
- intraclass correlation coefficient (1)
- lignite (1)
- limit analysis (1)
- lipopolysaccharide (1)
- lipopolysaccharides (1)
- load limit (1)
- long-term retention (1)
- low-rank coal (1)
- mechanical buffer (1)
- metagenomics (1)
- microbial diversity (1)
- multimodal (1)
- muscle mechanics (1)
- nanostructured carbonized plant parts (1)
- nanostrukturierte carbonisierte Pflanzenteile (1)
- non-simplex S-FEM elements (1)
- overload (1)
- parabolic flight (1)
- performance testing (1)
- physiology (1)
- pipes (1)
- plant scanner (1)
- plant stress (1)
- practical learning (1)
- prevention (1)
- psychosocial (1)
- pullulan (1)
- ratchetting (1)
- rehabilitation (1)
- reliability of structures (1)
- retinal microvasculature (1)
- retinal vessels (1)
- running (1)
- rupture of the fibular ligament (1)
- sEMG (1)
- sarcomere operating length (1)
- series elastic element behavior (1)
- shakedown (1)
- shotgun sequencing (1)
- shoulder (1)
- simulation (1)
- smooth muscle contraction (1)
- softs (1)
- soil amendment (1)
- soil health (1)
- soil remediation (1)
- sprint start (1)
- standard error of measurement (1)
- stiffness (1)
- stochastic programming (1)
- strain energy function (1)
- stretch reflex (1)
- stretch-shortening cycle (1)
- surface modification (1)
- survival (1)
- tendon rupture (1)
- tension–torsion loading (1)
- test-retest reliability (1)
- tri-lineage differentiation (1)
- twin-fluid atomizer (1)
- ultrasonography (1)
- unloading (1)
- vessels (1)
- videolaryngoscopy (1)
- virgin passive (1)
- viscoelasticity (1)
- walking (1)
- walking gait (1)
- wound healing (1)
- yield stress (1)
Picosecond dynamics in haemoglobin from different species: A quasielastic neutron scattering study
(2014)
Molecular-genetic identification of emerged novel invasive pathogens of Asiatic Elm Ulmus pumila L
(2014)
The dwarf elm Ulmus pumila L. (Ulmaceae) is one of indigenous species of flora in Kazakhstan and forms a basis of dendroflora in virtually all settlements of the region. In the past decade, multiple outbreaks of previously unknown diseases of the small-leaved elm have been registered. In our study, by the molecular-genetic analysis it was found that the pathogens responsible for the outbreaks are microfungi belonging to the genus Fusarium – F. solani and F. oxysporum. The nucleotide sequences (ITS regions) isolated from the diseased trees showed very high similarity with the GenBank control numbers EU625403.1 and FJ478128.1 (100.0 and 99.0 % respectively). Oncoming research will focus on the search of natural microbial antagonists of the discovered phytopathogens.
The scope of this study is the measurement of endotoxin adsorption rate for carbonized rice husk. It showed good adsorption properties for LPS. During the batch experiments, several techniques were used and optimized for improving the material’s adsorption behavior. Also, with the results obtained it was possible to differentiate the materials according to their adsorption capacity and kinetic characteristics.
Background
True date palms (Phoenix dactylifera L.) are impressive trees and have served as an indispensable source of food for mankind in tropical and subtropical countries for centuries. The aim of this study is to differentiate date palm tree varieties by analysing leaflet cross sections with technical/optical methods and artificial neural networks (ANN).
Results
Fluorescence microscopy images of leaflet cross sections have been taken from a set of five date palm tree cultivars (Hewlat al Jouf, Khlas, Nabot Soltan, Shishi, Um Raheem). After features extraction from images, the obtained data have been fed in a multilayer perceptron ANN with backpropagation learning algorithm.
Conclusions
Overall, an accurate result in prediction and differentiation of date palm tree cultivars was achieved with average prediction in tenfold cross-validation is 89.1% and reached 100% in one of the best ANN.
Two single-incision mini-slings used for treating urinary incontinence in women are compared with respect to the stresses they produce in their surrounding tissue. In an earlier paper we experimentally observed that these implants produce considerably different stress distributions in a muscle tissue equivalent. Here we perform 2D finite element analyses to compare the shear stresses and normal stresses in the tissue equivalent for the two meshes and to investigate their failure behavior. The results clearly show that the Gynecare TVT fails for increasing loads in a zipper-like manner because it gradually debonds from the surrounding tissue. Contrary to that, the tissue at the ends of the DynaMesh-SIS direct may rupture but only at higher loads. The simulation results are in good agreement with the experimental observations thus the computational model helps to interpret the experimental results and provides a tool for qualitative evaluation of mesh implants.
There is significant interest in sampling subglacial environments for geobiological studies, but they are difficult to access. Existing ice-drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. The IceMole is a maneuverable subsurface ice probe for clean in situ analysis and sampling of glacial ice and subglacial materials. The design is based on the novel concept of combining melting and mechanical propulsion. It can change melting direction by differential heating of the melting head and optional side-wall heaters. The first two prototypes were successfully tested between 2010 and 2012 on glaciers in Switzerland and Iceland. They demonstrated downward, horizontal and upward melting, as well as curve driving and dirt layer penetration. A more advanced probe is currently under development as part of the Enceladus Explorer (EnEx) project. It offers systems for obstacle avoidance, target detection, and navigation in ice. For the EnEx-IceMole, we will pay particular attention to clean protocols for the sampling of subglacial materials for biogeochemical analysis. We plan to use this probe for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, with return of a subglacial brine sample.
This paper develops a new finite element method (FEM)-based upper bound algorithm for limit and shakedown analysis of hardening structures by a direct plasticity method. The hardening model is a simple two-surface model of plasticity with a fixed bounding surface. The initial yield surface can translate inside the bounding surface, and it is bounded by one of the two equivalent conditions: (1) it always stays inside the bounding surface or (2) its centre cannot move outside the back-stress surface. The algorithm gives an effective tool to analyze the problems with a very high number of degree of freedom. Our numerical results are very close to the analytical solutions and numerical solutions in literature.
The necessity of e-books as a primary of learning, its opportunities for realization of competence during training biologist and biotechnologist specialists are determined. Definitions and requirements to the e-books, its advantages in comparison with traditional textbooks, and the ways of creation of e-books in the SunRav BookEditor program are considered.
One of the priority trends of carbon nanotechnology is creation of nanocomposite systems. Such carbon nanostructured composites were produced using - raw materials based on the products of agricultural waste, such as grape stones, apricot stones, rice husk. These products have a - wide spectrum of application and can be obtained in large quantities. The Institute of Combustion Problems has carried out the work on synthesis of the nanostructured carbon sorbents for multiple applications including the field of biomedicine. The article presents the data on the synthesis and physico-chemical properties of carbonaceous sorbents using physicochemical methods of investigation: separation and purification of biomolecules; isolation of phytohormone - fusicoccin; adsorbent INGO-1 in the form of an adsorption column for blood detoxification, oral (entero) sorbent - INGO-2; the study of efferent and probiotic properties and sorption activity in regard to the lipopolysaccharide (LPS), new biocomposites - based on carbonized rice husk (CRH) and cellular microorganisms; the use of CRH in wound treatment. A new material for blood detoxication (INGO-1) has been obtained. Adsorption of p-cresyl sulfate and indoxyl sulfate has shown that active carbon adsorbent can remove clinically significant level of p-cresyl sulfate and indoxyl sulfate from human plasma. Enterosorbent INGO-2 possesses high adsorption activity in relation to Gram-negative bacteria and their endotoxins. INGO-2 slows down the growth of conditionally pathogenic microorganisms, without having a negative effect on bifido and lactobacteria. The use of enterosorbent INGO-2 for sorption therapy may provide a solution to a complex problem - detoxication of the digestive tract and normalization of the intestinal micro ecology. The immobilized probiotic called "Riso-lact" was registered at the Ministry of Health of the Republic of Kazakhstan as a biologically active food additive. The developed technology is patented and provides production of the medicine in the form of freeze-dried biomass immobilized in vials.
The carbonized rice husk (CRH) was evaluated for its wound healing activity in rats using excision models. In this study, the influences of CRH on wound healing in rat skin in vivo and cellular behavior of human dermal fibroblasts in vitro were investigated. The obtained results showed that the CRH treatment promoted wound epithelization in rats and exhibited moderate inhibition of cell proliferation in vitro. CRH with lanolin oil treated wounds were found to epithelize faster as compared to controls.
Optical coherence tomography : a potential tool to predict premature rupture of fetal membranes
(2013)
Einschränkung von Taluskippung und -vorschub durch Sprunggelenkorthesen nach fibularer Bandruptur
(2013)
Die fibulare Bandruptur zählt zu einer der am häufigsten auftretenden Verletzungen des
Bewegungsapparats. In den meisten Fällen wird heute die konservativ frühfunktionelle Therapie mit Sprunggelenkorthesen allgemein bevorzugt. Im Rahmen der vorliegenden Studie wurden 14 verschiedene Sprunggelenkorthesen im Hinblick auf ihre Einschränkung von Taluskippung und Talusvorschub
untersucht. Zur Simulation einer fibularen Bandruptur wurde ein Unterschenkelmodell aus Holz mit Fußteil, mit angelegten Orthesen in einen Scheuba-Halteapparat eingespannt und mit 150 N seitlich sowie anterior-posterior belastet. Anhand der erstellten "gehaltenen" Röntgenaufnahmen konnten Taluskippung und Talusvorschub jeder einzelnen Orthese eindeutig bestimmt werden. Die meisten Orthesen erreichten zufriedenstellende Ergebnisse. Es stellte sich heraus, dass vor allem eine eng anliegende, im Gelenkbereich anatomisch angepasste Form vorteilhaft zu sein scheint.
Temperature-dependent ranges of coexistence in a model of a two-prey-one-predator microbial food web
(2012)
The objective of our study was to analyze the effects of temperature on the population dynamics of a three-species food web consisting of two prey bacteria (Pedobacter sp. and Acinetobacter johnsonii) and a protozoan predator (Tetrahymena pyriformis) as model organisms. We assessed the effects of temperature on the growth rates of all three species with the objective of developing a model with four differential equations based on the experimental data. The following hypotheses were tested at a theoretical level: Firstly, temperature changes can affect the dynamic behavior of a system by temperature-dependent parameters and interactions and secondly, food web response to temperature cannot be derived from the single species temperature response. The main outcome of the study is that temperature changes affect the parameter range where coexistence is possible within all three species. This has significant consequences on our ideas regarding the evaluation of effects of global warming.
Purpose: It was demonstrated previously that retinal pulse wave velocity (rPWV) as a measure of retinal arterial stiffness is increased in aged anamnestically healthy volunteers compared with young healthy subjects. Using novel methodology of rPWV assessment this finding was confirmed and investigated whether it might relate to the increased blood pressure usually accompanying the aging process, rather than to the aging itself.
Methods: A total of 12 young 25.5-year-old (24.0–28.8) [median(1st quartile–3rd quartile)] and 12 senior 68.5-year-old (63.8–71.8) anamnestically healthy volunteers; and 12 senior 63.0-year-old (60.8–65.0) validated healthy volunteers and 12 young 33.0-year-old (29.5–35.0) hypertensive patients were examined. Time-dependent alterations of vessel diameter were assessed by the Dynamic Vessel Analyzer in a retinal artery of each subject. The data were filtered and processed using mathematical signal analysis and rPWVs were calculated.
Results: rPWV amounted to 1200 (990-1470) RU (relative units)/s in the hypertensive group and to 1040 (700-2230) RU/s in anamnestically healthy seniors. These differed significantly from rPWVs in young healthy group (410 [280–500] RU/s) and in validated healthy seniors (400 [320–510] RU/s). rPWV associated with age and mean arterial pressure (MAP) in the pooled cohort excluded validated healthy seniors. In a regression model these associations remain when alternately adjusted for MAP and age. When including validated healthy seniors in the pooled cohort only association with MAP remains.
Conclusions: Both aging (with not excluded cardiovascular risk factors) and mild hypertension are associated with elevated rPWV. rPWV increases to a similar extent both in young mildly hypertensive subjects and in aged anamnestically healthy persons. Healthy aging is not associated with increased rPWV.
All cells generate contractile tension. This strain is crucial for mechanically controlling the cell shape, function and survival. In this study, the CellDrum technology quantifying cell's (the cellular) mechanical tension on a pico-scale was used to investigate the effect of lipopolysaccharide (LPS) on human aortic endothelial cell (HAoEC) tension. The LPS effect during gram-negative sepsis on endothelial cells is cell contraction causing endothelium permeability increase. The aim was to finding out whether recombinant activated protein C (rhAPC) would reverse the endothelial cell response in an in-vitro sepsis model. In this study, the established in-vitro sepsis model was confirmed by interleukin 6 (IL-6) levels at the proteomic and genomic levels by ELISA, real time-PCR and reactive oxygen species (ROS) activation by florescence staining. The thrombin cellular contraction effect on endothelial cells was used as a positive control when the CellDrum technology was applied. Additionally, the Ras homolog gene family, member A (RhoA) mRNA expression level was checked by real time-PCR to support contractile tension results. According to contractile tension results, the mechanical predominance of actin stress fibers was a reason of the increased endothelial contractile tension leading to enhanced endothelium contractility and thus permeability enhancement. The originality of this data supports firstly the basic measurement principles of the CellDrum technology and secondly that rhAPC has a beneficial effect on sepsis influenced cellular tension. The technology presented here is promising for future high-throughput cellular tension analysis that will help identify pathological contractile tension responses of cells and prove further cell in-vitro models.
Influence of a freeze–thaw cycle on the stress–stretch curves of tissues of porcine abdominal organs
(2012)
The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze–thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze–thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.
Suburethral slings as well as different meshes are widely used treating stress urinary incontinence and prolaps in women. With the development of MiniSlings and special meshes using less alloplastic material anchorage systems become more important to keep devices in place and to put some tension especially on the MiniSlings. To date, there are many different systems of MiniSlings of different companies on the market which differ in the structure of the used meshes and anchors. A new objective measurement method to compare different properties of MiniSling systems (mesh and anchor) is presented in this article. Ballistic gelatine acts as soft tissue surrogate. Significant differences in parameters like pull-out strength of anchors or shrinkage of meshes under loading conditions have been determined. The form and size of the anchors as well as the structural stability of the meshes are decisive for a proper integration. The tested anchorings sytems showed markedly different mechanical function at their respective load bearing capacity. As the stable fixation of the device in tissue is a prerequisite for a permanet reinforcement, the proposed test system permits further optimisation of anchor and mesh devices to improve the success of the surgical treatment
The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge.
Diese Studie beschäftigte sich mit der Dämpfungswirkung von Schienbeinschonern, wie sie beim Fußball zum Einsatz kommen. Sie wurde mit Hilfe eines Pendelhammers durchgeführt, der verschiedene Aufschlagkräfte auf die Schoner ermöglichte. Dabei wurde deutlich, dass Schienbeinschoner die beste Wirkung bei Maximalkräften unterhalb von 5kN erreichen können, dass bei größerer Belastung allerdings Verbesserungsbedarf besteht. Hierfür konnte, u.a. durch den Einsatz neuer Materialien, ein guter Ansatzpunkt im „adäquaten Zusammenspiel von Schale und Polsterung“ der Schoner gefunden werden. Die Untersuchung hat weiterhin gezeigt, dass zumindest teilweise eine deutliche Verbesserung der Dämpfungswirkung der Schienbeinschoner in den letzten Jahren erreicht werden konnte.
Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits.
There is common agreement within the scientific community that in order to understand our local galactic environment it will be necessary to send a spacecraft into the region beyond the solar wind termination shock. Considering distances of 200 AU for a new mission, one needs a spacecraft traveling at a speed of close to 10 AU/yr in order to keep the mission duration in the range of less than 25 yrs, a transfer time postulated by European Space Agency (ESA). Two propulsion options for the mission have been proposed and discussed so far: the solar sail propulsion and the ballistic/radioisotope-electric propulsion (REP). As a further alternative, we here investigate a combination of solar-electric propulsion (SEP) and REP. The SEP stage consists of six 22-cms diameter RIT-22 ion thrusters working with a high specific impulse of 7377 s corresponding to a positive grid voltage of 5 kV. Solar power of 53 kW at begin of mission (BOM) is provided by a lightweight solar array.
Determination of the frictional coefficient of the implant-antler interface : experimental approach
(2012)
The similar bone structure of reindeer antler to human bone permits studying the osseointegration of dental implants in the jawbone. As the friction is one of the major factors that have a significant influence on the initial stability of immediately loaded dental implants, it is essential to define the frictional coefficient of the implant-antler interface. In this study, the kinetic frictional forces at the implant-antler interface were measured experimentally using an optomechanical setup and a stepping motor controller under different axial loads and sliding velocities. The corresponding mean values of the static and kinetic frictional coefficients were within the range of 0.5–0.7 and 0.3–0.5, respectively. An increase in the frictional forces with increasing applied axial loads was registered. The measurements showed an evidence of a decrease in the magnitude of the frictional coefficient with increasing sliding velocity. The results of this study provide a considerable assessment to clarify the suitable frictional coefficient to be used in the finite element contact analysis of antler specimens.
Background
Minor changes in protein structure induced by small organic and inorganic molecules can result in significant metabolic effects. The effects can be even more profound if the molecular players are chemically active and present in the cell in considerable amounts. The aim of our study was to investigate effects of a nitric oxide donor (spermine NONOate), ATP and sodium/potassium environment on the dynamics of thermal unfolding of human hemoglobin (Hb). The effect of these molecules was examined by means of circular dichroism spectrometry (CD) in the temperature range between 25°C and 70°C. The alpha-helical content of buffered hemoglobin samples (0.1 mg/ml) was estimated via ellipticity change measurements at a heating rate of 1°C/min.
Results
Major results were:
1) spermine NONOate persistently decreased the hemoglobin unfolding temperature T u irrespectively of the Na + /K + environment,
2) ATP instead increased the unfolding temperature by 3°C in both sodium-based and potassium-based buffers and
3) mutual effects of ATP and NO were strongly influenced by particular buffer ionic compositions. Moreover, the presence of potassium facilitated a partial unfolding of alpha-helical structures even at room temperature.
Conclusion
The obtained data might shed more light on molecular mechanisms and biophysics involved in the regulation of protein activity by small solutes in the cell.
Upper and lower bound theorems of limit analyses have been presented in part I of the paper. Part II starts with the finite element discretization of these theorems and demonstrates how both can be combined in a primal–dual optimization problem. This recently proposed numerical method is used to guide the development of a new class of closed-form limit loads for circumferential defects, which show that only large defects contribute to plastic collapse with a rapid loss of strength with increasing crack sizes. The formulae are compared with primal–dual FEM limit analyses and with burst tests. Even closer predictions are obtained with iterative limit load solutions for the von Mises yield function and for the Tresca yield function. Pressure loading of the faces of interior cracks in thick pipes reduces the collapse load of circumferential defects more than for axial flaws. Axial defects have been treated in part I of the paper.