The artificial neuron proposed earlier for use in superconducting neural networks is experimentally studied. The fabricated sample is a single-junction interferometer, part of the circuit of which is ...shunted by an additional inductance, which is also used to generate an output signal. A technological process has been developed and tested to fabricate a neuron in the form of a multilayer thin-film structure over a thick superconducting screen. The transfer function of the fabricated sample, which contains sigmoid and linear components, is experimentally measured. A theoretical model is developed to describe the relation between input and output signals in a practical superconducting neuron. The derived equations are shown to approximate experimental curves at a high level of accuracy. The linear component of the transfer function is shown to be related to the direct transmission of an input signal to a measuring circuit. Possible ways for improving the design of the sigma neuron are considered.
Standard microorganism isolating technology applied for complex multiphase environmental samples such as soil or sediment needs pre-treatment steps to remove living cells from their mixed-phase ...microniche, by creating a liquid-phase sample. This process removes synergetic relationships, which help to maintain viability of yet-to-be-cultured and hard-to-culture bacteria. In this paper we demonstrate a high throughput Laser Micro-Sampling (LMS) technology for direct isolation of pure microbial cultures and microbial consortia from soil. This technology is based on laser printing of soil microparticles by focusing near-infrared laser pulses on specially prepared samples of a soil/gel mixture spread onto a gold-coated glass plate. Microsamples of soil are printed on glucose-peptone-yeast agar plates, to estimate the LMS process influence on functional and taxonomic microbial diversity, and on «Eco-log» sole carbon sources microplates, to investigate functional diversity by "metabolic fingerprinting". The obtained results are compared with traditionally treated soil samples. It was shown that LMS treatment leads to increasing of cultured biodiversity and modifies the functional diversity. The strain of rare genus Nonomuraea was isolated by LMS from complex natural environment without using media selective for this genus.
Recently, it was shown that laser‐induced forward transfer (LIFT) technology and the laser engineering of microbial systems (LEMS) technique (based on LIFT method) are effective for isolation of ...micro‐organisms from different complex substrates. These techniques frequently utilize Au as an absorbing layer material. The purpose of this study was to investigate the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness of laser printing of micro‐organisms to improve LEMS and LIFT techniques. It was shown that application of Ti and Cr absorbing layers activates bacterial growth after laser printing and is significantly more effective in comparison to Au films, which actually show a suppressing effect on bacterial cells. Results of this study can be applied for LEMS and LIFT protocols for improving bacterial isolation and microbial growth.
Significance and Impact of the Study
Laser‐induced forward transfer technique (LIFT) is currently used for printing of micro‐organisms and in biosensor techniques, for single‐cell isolation, and for culturing of micro‐organisms from complex substrates. We have studied the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness laser printing of micro‐organisms. It was shown that application of Ti and Cr absorbing layers activates bacterial growth and is more effective in LIFT compared to Au films, which actually have a suppressive effect on bacteria cells. The results can improve LIFT protocols for bacteria isolation and culturing of microbial systems.
Significance and Impact of the Study: Laser‐induced forward transfer technique (LIFT) is currently used for printing of micro‐organisms and in biosensor techniques, for single‐cell isolation, and for culturing of micro‐organisms from complex substrates. We have studied the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness laser printing of micro‐organisms. It was shown that application of Ti and Cr absorbing layers activates bacterial growth and is more effective in LIFT compared to Au films, which actually have a suppressive effect on bacteria cells. The results can improve LIFT protocols for bacteria isolation and culturing of microbial systems.
We investigate thermal contact resistance of a detachable connection in the copper–copper contact pair with a thermal interface made of graphene layers synthesized by chemical vapor deposition onto ...the contacting surface. The values of the thermal contact resistance of a detachable copper–graphene–copper contact pair were obtained using the transient heat flow method in the temperature range of 15–150 K under the influence of an external magnetic field of up to 10 T.
Electrodeposition of cobalt on monolayer graphene synthesized by chemical vapor deposition produces Co–CoO/graphene composite structures, which is accompanied by increases in the electrical ...resistance and magnetoresistance. We show that the observed magnetoresistance effect is caused by two competing contributions: negative (NMR) and positive (PMR) magnetoresistance. In weak magnetic fields, the NMR is described by quantum localization correction to the Drude model of conductivity in graphene. The enhancement of PMR observed in strong magnetic fields is related to the Lorentz mechanism in Co–CoO particles.
Recent studies on piezoelectricity in 2D materials, such as graphene, have revealed their potential in multiple applications including microelectromechanical systems. In this work, we reveal ...piezoelectricity in few-layer graphene sheets deposited on amorphous Si
3
N
4
membranes. The response in the center of square membrane of 6.7 × 6.7 mm
2
size reaches about 14 nm at resonance and could be further enhanced by adjusting the composite structure. Resonance piezoelectric phenomena are fully consistent with the earlier piezoresponse force microscopy observations on free-standing piezoelectric graphene and open up a possibility of using 2D materials in micromechanical applications.
Bidomain single crystals of lithium niobate (LiNbO
3
) and lithium tantalate (LiTaO
3
) are promising materials for use as actuators, mechanoelectrical transducers, and sensors capable of working in ...a wide temperature range. One need to take into account the anisotropy of the properties of the crystalline material when such devices are designed. In this study we investigated deformations of bidomain round shaped
Y
+ 128°-cut wafers of lithium niobate in an external electric field. The dependences of the piezoelectric coefficients on the rotation angles were calculated for lithium niobate and lithium tantalate and plotted for the crystal cuts which are used for the formation of a bidomain ferroelectric structure. In the experiment, we utilized an external heating method and long-time annealing with the lithium out-diffusion method in order to create round bidomain lithium niobate wafers. Optical microscopy was used to obtain the dependences of the bidomain crystals’ movements on the rotation angle with central fastening and the application of an external electric field. We also modelled the shape of the deformed bidomain wafer with the suggestion that the edge movement depends on the radial distance to the fastening point quadratically. In conclusion, we revealed that the bidomain Y + 128°-cut lithium niobate wafer exhibits a saddle-like deformation when a DC electric field is applied.
Hydrogel matrices for cell cultivation have been generated by two-photon laser polymerization of unsaturated chitosan derivatives and methacrylated hyaluronic acid. The adhesive and toxic properties ...of the matrices have been assessed, and the matrices have been shown to have a good compatibility with primary hippocampal cell cultures. The formation of morphologically normal neural networks by cells of the nervous system cultured on the surface of hydrogel matrices has been observed. The metabolic status of dissociated hippocampal cells cultured on the matrices was similar to that of the control cultures, as shown by the results of MTT reductase activity assay. Thus, matrices based on unsaturated polysaccharide derivatives crosslinked by laser irradiation showed good compatibility with differentiated cells of the nervous system and considerable potential for use in neurotransplantation.
We developed and tested new 3D scaffolds for neurotransplantation. Scaffolds of predetermined architectonic were prepared using microstereolithography technique. Scaffolds were highly biocompatible ...with the nervous tissue cells.
In vitro
studies showed that the material of fabricated scaffolds is not toxic for dissociated brain cells and promotes the formation of functional neural networks in the matrix. These results demonstrate the possibility of fabrication of tissue-engineering constructs for neurotransplantation based on created scaffolds.
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