TY  - JOUR
A1  - Uysal, Karya
A1  - Creutz, Till
A1  - Firat, Ipek Seda
A1  - Artmann, Gerhard
A1  - Teusch, Nicole
A1  - Temiz Artmann, Aysegül
T1  - Bio-functionalized ultra-thin, large-area and waterproof silicone membranes for biomechanical cellular loading and compliance experiments
JF  - Polymers
N2  - Biocompatibility, flexibility and durability make polydimethylsiloxane (PDMS) membranes top candidates in biomedical applications. CellDrum technology uses large area, <10 µm thin membranes as mechanical stress sensors of thin cell layers. For this to be successful, the properties (thickness, temperature, dust, wrinkles, etc.) must be precisely controlled. The following parameters of membrane fabrication by means of the Floating-on-Water (FoW) method were investigated: (1) PDMS volume, (2) ambient temperature, (3) membrane deflection and (4) membrane mechanical compliance. Significant differences were found between all PDMS volumes and thicknesses tested (p < 0.01). They also differed from the calculated values. At room temperatures between 22 and 26 °C, significant differences in average thickness values were found, as well as a continuous decrease in thicknesses within a 4 °C temperature elevation. No correlation was found between the membrane thickness groups (between 3–4 µm) in terms of deflection and compliance. We successfully present a fabrication method for thin bio-functionalized membranes in conjunction with a four-step quality management system. The results highlight the importance of tight regulation of production parameters through quality control. The use of membranes described here could also become the basis for material testing on thin, viscous layers such as polymers, dyes and adhesives, which goes far beyond biological applications.
Y1  - 2022
SN  - 2073-4360
VL  - 14
IS  - 11
SP  - 2213
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Mansurov, Z.
A1  - Digel, Ilya
A1  - Biisenbaev, M.
A1  - Savistkaya, I.
A1  - Kistaubaeva, A.
A1  - Akimbekov, Nuraly S.
A1  - Zhubanova, A.
T1  - Bio-composite material on the basis of carbonized rice husk in biomedicine and environmental applications
JF  - Eurasian Chemico-Technological Journal
Y1  - 2012
U6  - https://doi.org/10.18321/ectj105
SN  - 2522-4867
VL  - 14
IS  - 2
SP  - 115
EP  - 131
PB  - Institute of Combustion Problems
CY  - Almaty
ER  - 
TY  - CHAP
A1  - Staat, Manfred
A1  - Heitzer, M.
T1  - Basis reduction technique for limit and shakedown problems
T2  - Numerical Methods for Limit and Shakedown Analysis. Deterministic and Probabilistic Approach. NIC Series Vol. 15 / Ed. by Staat, M.; Heitzer, M.
Y1  - 2003
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0001-2018112115
SN  - 3-00-010001-6
SP  - 1
EP  - 55
PB  - John von Neumann Institute for Computing (NIC)
CY  - Jülich
ER  - 
TY  - JOUR
A1  - Staat, Manfred
T1  - Basis Reduction for the Shakedown Problem for Bounded Kinematic Hardening Material
N2  - Limit and shakedown analysis are effective methods for assessing the load carrying capacity of a given structure. The elasto–plastic behavior of the structure subjected to loads varying in a given load domain is characterized by the shakedown load factor, defined as the maximum factor which satisfies the sufficient conditions stated in the corresponding static shakedown theorem. The finite element dicretization of the problem may lead to very large convex optimization. For the effective solution a basis reduction method has been developed that makes use of the special problem structure for perfectly plastic material. The paper proposes a modified basis reduction method for direct application to the two-surface plasticity model of bounded kinematic hardening material. The considered numerical examples show an enlargement of the load carrying capacity due to bounded hardening.
KW  - Finite-Elemente-Methode
KW  - Einspielen <Werkstoff>
KW  - Basis Reduktion
KW  - konvexe Optimierung
KW  - FEM
KW  - Druckgeräte
KW  - Basis reduction
KW  - Convex optimization
KW  - FEM
KW  - Shakedown analysis
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Digel, Ilya
A1  - Temiz Artmann, Aysegül
A1  - Nishikawa, K.
A1  - Cook, M.
T1  - Bactericidal effects of plasma-generated cluster ions
JF  - Medical and Biological Engineering and Computing. 43 (2005), H. 6
Y1  - 2005
SN  - 1741-0444
SP  - 800
EP  - 807
ER  - 
TY  - JOUR
A1  - Digel, Ilya
A1  - Akimbekov, Nuraly S.
A1  - Rogachev, Evgeniy
A1  - Pogorelova, Natalia
T1  - Bacterial cellulose produced by Medusomyces gisevii on glucose and sucrose: biosynthesis and structural properties
JF  - Cellulose
N2  - In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) synthesized by Medusomyces gisevii have been studied. The culture medium was composed of different initial concentrations of glucose or sucrose dissolved in 0.4% extract of plain green tea. Parameters of the culture media (titratable acidity, substrate conversion degree etc.) were monitored daily for 20 days of cultivation. The BC pellicles produced on different carbon sources were characterized in terms of biomass yield, crystallinity and morphology by field emission scanning electron microscopy (FE-SEM), atomic force microscopy and X-ray diffraction. Our results showed that Medusomyces gisevii had higher BC yields in media with sugar concentrations close to 10 g L−1 after a 18–20 days incubation period. Glucose in general lead to a higher BC yield (173 g L−1) compared to sucrose (163.5 g L−1). The BC crystallinity degree and surface roughness were higher in the samples synthetized from sucrose. Obtained FE-SEM micrographs show that the BC pellicles synthesized in the sucrose media contained densely packed tangles of cellulose fibrils whereas the BC produced in the glucose media displayed rather linear geometry of the BC fibrils without noticeable aggregates.
KW  - Bacterial cellulose
KW  - Medusomyces gisevi
KW  - Carbon sources
KW  - Culture media
KW  - Cellulose nanostructure
Y1  - 2023
U6  - https://doi.org/10.1007/s10570-023-05592-z
SN  - 1572-882X (Online)
SN  - 0969-0239 (Print)
N1  - Corresponding author: Ilya Digel
PB  - Springer Science + Business Media
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Pogorelova, Natalia
A1  - Rogachev, Evgeniy
A1  - Digel, Ilya
A1  - Chernigova, Svetlana
A1  - Nardin, Dmitry
T1  - Bacterial Cellulose Nanocomposites: Morphology and Mechanical Properties
JF  - Materials
N2  - Bacterial cellulose (BC) is a promising material for biomedical applications due to its unique properties such as high mechanical strength and biocompatibility. This article describes the microbiological synthesis, modification, and characterization of the obtained BC-nanocomposites originating from symbiotic consortium Medusomyces gisevii. Two BC-modifications have been obtained: BC-Ag and BC-calcium phosphate (BC-Ca3(PO4)2). Structure and physicochemical properties of the BC and its modifications were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and infrared Fourier spectroscopy as well as by measurements of mechanical and water holding/absorbing capacities. Topographic analysis of the surface revealed multicomponent thick fibrils (150–160 nm in diameter and about 15 µm in length) constituted by 50–60 nm nanofibrils weaved into a left-hand helix. Distinctive features of Ca-phosphate-modified BC samples were (a) the presence of 500–700 nm entanglements and (b) inclusions of Ca3(PO4)2 crystals. The samples impregnated with Ag nanoparticles exhibited numerous roundish inclusions, about 110 nm in diameter. The boundaries between the organic and inorganic phases were very distinct in both cases. The Ag-modified samples also showed a prominent waving pattern in the packing of nanofibrils. The obtained BC gel films possessed water-holding capacity of about 62.35 g/g. However, the dried (to a constant mass) BC-films later exhibited a low water absorption capacity (3.82 g/g). It was found that decellularized BC samples had 2.4 times larger Young’s modulus and 2.2 times greater tensile strength as compared to dehydrated native BC films. We presume that this was caused by molecular compaction of the BC structure.
Y1  - 2020
SN  - 1996-1944
U6  - https://doi.org/10.3390/ma13122849
VL  - 13
IS  - 12
SP  - 1
EP  - 16
PB  - MDPI
CY  - Basel
ER  - 
TY  - CHAP
A1  - Pirovano, Laura
A1  - Seefeldt, Patric
A1  - Dachwald, Bernd
A1  - Noomen, Ron
T1  - Attitude and orbital modeling of an uncontrolled solar-sail experiment in low-Earth orbit
T2  - 25th International Symposium on Space Flight Dynamics ISSFD
N2  - Gossamer-1 is the first project of the three-step Gossamer roadmap, the purpose of which is to develop, prove and demonstrate that solar-sail technology is a safe and reliable propulsion technique for long-lasting and high-energy missions. This paper firstly presents the structural analysis performed on the sail to understand its elastic behavior. The results are then used in attitude and orbital simulations. The model considers the main forces and torques that a satellite experiences in low-Earth orbit coupled with the sail deformation. Doing the simulations for varying initial conditions in attitude and rotation rate, the results show initial states to avoid and maximum rotation rates reached for correct and faulty deployment of the sail. Lastly comparisons with the classic flat sail model are carried out to test the hypothesis that the elastic behavior does play a role in the attitude and orbital behavior of the sail
KW  - Solar sail
KW  - Gossamer structures
KW  - Attitude dynamics
KW  - Orbital dynamics
Y1  - 2015
N1  - 25th International Symposium on Space Flight Dynamics ISSFD
October 19 – 23, 2015, Munich, Germany
https://issfd.org/2015/
SP  - 1
EP  - 15
ER  - 
TY  - CHAP
A1  - Pirovano, Laura
A1  - Seefeldt, Patric
A1  - Dachwald, Bernd
A1  - Noomen, Ron
T1  - Attitude and Orbital Dynamics Modeling for an Uncontrolled Solar-Sail Experiment in Low-Earth Orbit
T2  - 25th International Symposium on Spaceflight Dynamics, 2015, Munich, Germany
Y1  - 2015
ER  - 
TY  - JOUR
A1  - Albracht, Kirsten
A1  - Arampatzis, Adamantios
A1  - Baltzopoulos, Vasilios
T1  - Assessment of muscle volume and physiological cross-sectional area of the human triceps surae muscle in vivo
JF  - Journal of Biomechanics
Y1  - 2008
U6  - https://doi.org/10.1016/j.jbiomech.2008.04.020
SN  - 0021-9290
VL  - 41
SP  - 2211
EP  - 2218
ER  -