Contact Density Research Articles

Hydrodynamics with spacetime-dependent scattering length

Hydrodynamics provides a concise but powerful description of long-time and long-distance physics of correlated systems out of thermodynamic equilibrium. Here we construct hydrodynamic equations for nonrelativistic particles with a spacetime-dependent scattering length and show that it enters constitutive relations uniquely so as to represent the fluid expansion and contraction in both normal and superfluid phases. As a consequence, we find that a leading dissipative correction to the contact density due to the spacetime-dependent scattering length is proportional to the bulk viscosity (${\ensuremath{\zeta}}_{2}$ in the superfluid phase). Also, when the scattering length is slowly varied over time in a uniform system, the entropy density is found to be produced even without fluid flows in proportion to the bulk viscosity, which may be useful as a novel probe to measure the bulk viscosity in ultracold-atom experiments.

Diagnostics of the pre-fault situation of the bolted current-carrying joint in the conditions of changing regime parameters

The object of research is the methods of non-destructive monitoring of the state of a bolted current-carrying joint under conditions of dynamically changing current load conditions and ambient temperature. One of the most problematic places in the modern conditions of economic development of enterprises is the reduction in the accident rate of production due to the weakening of the bolted current-carrying joint. Studies of the causes of stopping electrical equipment at a number of ferrous metallurgy enterprises, mining and processing complexes, in medical institutions have shown that in 1.5-2 % of cases the cause of an emergency shutdown of electrical equipment is the weakening of the bolted current-carrying joint. The main problem of the bolted current-carrying joint is the mechanical weakening of the contact density. The appearance of a temperature gradient in the place of a bolted joint is influenced by climatic parameters and dynamically changing modes of operating current loads and network voltage.The study of operating parameters of the network and load currents is based on the use of a technique for monitoring the quality of electricity indicators using self-recording spectrum analyzers. In this study, the spectrum analyzer Fluk 435 (Ukraine) is used, the characteristics of which correspond to the ISO 9001 measurement system certificate. Statistical processing methods are used as the basis for processing the experimentally obtained data.In the course of the study, the inequality between the measured temperature of the bolted current-carrying joint and the calculated temperature of the serviceable joint is determined. The inequality is fulfilled in the sections, the stationarity of which is determined for deterministic and random modes of change of the controlled parameters. The functions of Boolean variables are compiled, the disjunctive functions that determine the normal and pre-crash modes of the bolted joint are minimized. The obtained theoretical results allow developing algorithms and devices for diagnosing and protecting equipment.This provides the opportunity to reduce the accident rate of the equipment. Compared with similar well-known protection equipment, taking into account the modes of load currents, mains voltage and ambient temperature provides a high sensitivity and accuracy of detecting the initial moment of loosening of a bolted current-carrying joint.

Household members do not contact each other at random: implications for infectious disease modelling.

Airborne infectious diseases such as influenza are primarily transmitted from human to human by means of social contacts, and thus easily spread within households. Epidemic models, used to gain insight into infectious disease spread and control, typically rely on the assumption of random mixing within households. Until now, there has been no direct empirical evidence to support this assumption. Here, we present the first social contact survey specifically designed to study contact networks within households. The survey was conducted in Belgium (Flanders and Brussels) from 2010 to 2011. We analysed data from 318 households totalling 1266 individuals with household sizes ranging from two to seven members. Exponential-family random graph models (ERGMs) were fitted to the within-household contact networks to reveal the processes driving contact between household members, both on weekdays and weekends. The ERGMs showed a high degree of clustering and, specifically on weekdays, decreasing connectedness with increasing household size. Furthermore, we found that the odds of a contact between older siblings and between father and child are smaller than for any other pair. The epidemic simulation results suggest that within-household contact density is the main driver of differences in epidemic spread between complete and empirical-based household contact networks. The homogeneous mixing assumption may therefore be an adequate characterization of the within-household contact structure for the purpose of epidemic simulations. However, ignoring the contact density when inferring based on an epidemic model will result in biased estimates of within-household transmission rates. Further research regarding the implementation of within-household contact networks in epidemic models is necessary.

Quantum dynamics calculation of the annihilation spectrum for positron–proline scattering

The annihilation spectrum for positron scattering by the amino acid proline was calculated using local complex potential theory combined with the time-dependent quantum wave packet method. Two nuclear degrees of freedom associated with the motion of the carboxyl group proton were considered in the dynamics. The positronic potential energy surface and positron–electron contact densities were calculated using ab initio multi-component molecular orbital theory. The calculated annihilation spectrum contained several vibrational resonance peaks, which allowed the positron binding energies to be estimated. We also observed a resonance with a very small contribution of zwitterionic proline via proton transfer.

Suppression of GATA3 Binding Drives Selective Abrogation of NOTCH1-MYC Enhancer Activity By Nucleosome Invasion in Thymocyte Development and Leukemia

Long range enhancers play critical roles in the control of gene expression during development and have emerged as key regulators of lineage commitment and oncogenic programs in hematopoiesis and leukemia. The MYC oncogene is dynamically regulated in the hematopoietic system under the control of a network of clustered distal enhancers, which provide modular regulation of MYC expression during lymphoid and myeloid development. In thymocyte development MYC transcription critically depends on the activity of N-Me, a distinct T-cell specific enhancer controlled by NOTCH1 signaling and located 1.4 Mb telomeric to the MYC transcription start site. Yet, the specific mechanisms governing N-Me enhancer activity and lineage specific control of MYC expression remain rudimentarily understood. Analysis of chromatin looping by 4C and chromatin accessibility by ATACseq revealed an unanticipated high density of chromatin contacts between N-Me and additional regulatory elements in the Myc locus and showed a distinct pattern of N-Me chromatin accessibility -opening as progenitors mature into T cell committed CD4 CD8 double negative (DN) 2b cells and returning to a closed configuration in CD4 CD8 double positive (DP) thymocytes-. To explore potential regulators of N-Me activity we performed Mass Spectrometry proteomic profiling of N-Me binding proteins and ChIPseq analyses identifying numerous factors involved in hematopoietic and lymphoid development (ERG, ETS1, GATA3, RUNX1, TCF3 and TCF12) and transcription factor oncogenes with prominent roles in the pathogenesis of T-ALL (HOXA9, MYB, MYC, LMO1, LMO2, TAL1 and TLX1). Moreover, phylogenetic footprinting analyses across vertebrate species identified two ultraconserved elements matching GATA factor binding motifs (GS1 and GS2). To test the functionality of these elements we introduced targeted mutations in the N-Me sequence at these sites using CRISPR/CAS9 directed mutagenesis. Mice homozygous for combined N-Me GS1 and GS2 mutations (GS1+2mut) revealed a marked defect in thymus cellularity with characteristic accumulation of DN and intermediate single positive (ISP) thymocytes and decreased numbers of more mature populations. Mechanistically, immunohistochemical, flow cytometry and single cell RNaseq analyses revealed decreased Myc protein levels in thymocyte poulations of GS1+2 mutant animals. In this context, we hypothesized that GATA3, a prominent N-Me binding transcription factor in our ChIP and proteomic analyses critically implicated in T-cell commitment, could play a major role in N-Me regulation via interaction with the GS1 and GS2 N-Me GATA sites. Consistent with this hypothesis analysis of Gata3 ChIPs from heterozygous GS1+2 mutant mice recovered only the N-Me wild type sequence, formally demonstrating the strict requirement of these sites for N-Me Gata3 binding. Mechanistically, ATACseq analysis revealed a marked reduction in chromatin accessibility and nucleosome invasion in thymocytes from GS1+2 mutant mice in support of a critical pioneering activity for GATA3 in the control of N-Me activity. Finally, given the important role of NOTCH1 induced MYC upregulation in the pathogenesis of T-ALL, we hypothesized that disruption of N-Me activity via targeted mutation of N-Me GATA sites could effectively impair the development of NOTCH1-driven T-ALL in N-Me GS1+2 mutant mice. To test this possibility we infected hematopoietic progenitors from N-Me wild type and N-Me GS1+2 homozygous mice with retroviruses driving the expression of an oncogenic constitutively active form of NOTCH1 (DE-NOTCH1) and transplanted them into sublethally irradiated recipients. In these experiments, mice transplanted with DE-NOTCH1 infected N-Me wild type cells developed overt T-ALL 6 weeks postransplant with 100% penetrance. In contrast, mice transplanted with DE-NOTCH1-expressing N-Me GS1+2 homozygous cells showed complete protection from NOTCH1 induced T-ALL (P <0.001). In all these results identify GATA3 binding to the N-Me enhancer as a critical driver of nucleosome eviction and enhancer activation strictly required for thymocyte development and NOTCH1-induced T-cell transformation. DisclosuresNo relevant conflicts of interest to declare.

Focal amplification and suppression of West Nile virus transmission associated with communal bird roosts in northern Colorado.

To explain the patchy distribution of West Nile virus (WNV), we propose that avian immunity encountered by Culex vectors regulates WNV transmission, particularly at communal bird roosts. To test this hypothesis, we selected two test sites with communally roosting American robins (Turdus migratorius) and two control sites that lacked communal roosts. The density of vector-vertebrate contacts, represented by engorged Culex pipiens, was 23-fold greater at test sites compared to control sites, and the density of blood-engorged Cx. pipiens measured in resting mosquito traps correlated positively with the presence of robins and negatively with the presence of other birds, confirming an attraction to robins for blood feeding. WNV transmission was alternately up-regulated (amplification) and down-regulated (suppression) at both test sites. At one test site, infection in resting Cx. pipiens surged from zero to 37.2 per thousand within four weeks, and robin immunity rose from 8.4% to 64% before reducing to 33%. At this site, ten potentially infectious contacts between vector and vertebrates (including nine robins and a mourning dove [Zenaida macroura]) were documented. Infectious vector-vertebrate contacts were absent from control sites. The use of infectious vector-vertebrate contacts, rather than infected mosquitoes, to evaluate a transmission focus is novel.

Neurons Communication in the Hippocampus of Field CA3 of the White Rat Brain after Acute ischemia

The aim of this studywas to compare the pyramidal neurons, their processes and synapses in the stratum lucidum, stratum radiatum and stratum lacunosum of the molecular layer of the field CA3 of the hippocampus of the brain of white rats in the normal state and after acute ischemia caused by a 20-minute occlusion of the common carotid arteries.Materials and methods.In the experiment, using histological methods (hematoxylin and eosin, staining by Nissle and immunohistochemistry for p38, MAP-2) and electron microscopy, the pyramidal neurons of field CA3, their processes and synapses in stratum lucidum, stratum radiatum and stratum lacunosum of the molecular layer were studied. The main group included animals in the reperfusion period (1, 3, 7, 14, 21, and 30 days;n=30), comparison group — falsely operated animals (n=20). Morphometric analysis was performed using ImageJ 1.46, the verification of statistical hypotheses — Statistica 8.0.Results.After occlusion of the common carotid arteries (CCAO) in the field CA3 of hippocampus, reactive, compensatory and reparative reorganization of pyramidal neurons and their communication structures was noted. On day 1, there was a decrease, and then (days 3—14) restoration of the total number of synapses and of P38-positive material within the area of synapses. According to electron microscopy, in the early post-ischemic period, the total numerical density of synaptic contacts in the stratum lacunosum of the molecular layer decreased by 44.8%, and after 14 days recovered to control. In stratum lucidum, the area of P38-positive material decreased by 8.8% after 1 day, and recovered after 3—7 days.Conclusion.After the CCAO, the communication systems of the pyramid neurons of the field CA3 hippocampus of white rats were reorganized. Neurons of the field CA3 had high tolerance to ischemia and ability to restore interneural relations after reperfusion. In the surviving neurons, high levels of the cytoskeleton (MAP-2) marker and synaptic vesicles (p38) were detected. Data demonstrate structural and functional safety of all components of the communication system of a significant part of pyramidal neurons in acute ischemia. After reperfusion, the most significant alterations included the reconstructed interneuron synapses in the stratum radiatum and the lacunosum molecular layer.

СРАВНИТЕЛЬНАЯ ХАРАКТЕРИСТИКА ПЛОТНОСТИ ПРИЛЕГАНИЯ КЕРАМИЧЕСКИХ ВКЛАДОК — ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ

Importance. The development of digital dentistry allows the use of new technologies to create orthopedic structures. Scanners in orthopedic dentistry are becoming an integral part of quality prosthetics. To work with new scanners requires not only the ability to perform the scanning procedure itself, but also to understand how accurately the scanner reproduces the surface relief. To determine the contact density of all-ceramic inserts in the removed teeth, this study was carried out.&#x0D; Objectives. Experimental comparison of the accuracy of the adhesion of all-ceramic inserts made using the VT Dental scanner (Russia).&#x0D; Methods. The study was conducted at the Department of Orthopedic Dentistry of the State Pedagogical University in the UGMU, in the Urals Branch of the RAS of the Institute of Geology and Geochemistry. acad. A.N. Zavaritsky - in the laboratory of physical and chemical methods of research. Removed molars and premolars of the upper and lower jaws in an amount of 20 pcs. They were processed, prepared under the all-ceramic inserts on the occlusal surfaces. Scanners for registering the relief of cavities: VT Dental (Russia), D500 (3Shape, Denmark), InEos Blue (DentsplySirona, Germany). The device for milling: Wieland dental zenotec select hybrid. The material of the tabs is E.MAX Press (Ivoclar Vivadent, Germany). Cements for fixation: RelyX Ultimate (3M ESPE, USA), Multilink Automix (Ivoclar Vivadent, Germany), MaxCem Elite (Kerr, Italy). The made inserts were fixed in equal parts in the cavities of the removed teeth on the presented cements, longitudinal sections of the remote molars and premolars were created. The method of investigation is scanning electron microscopy. Statistical processing was carried out in Gretl software.&#x0D; Results. As a result of the scanning electron microscopy of 20 sections in aggregate, data were obtained on the accuracy of the adherence of a ceramic insert made using a VT Dental scanner (Russia) that did not significantly differ from the data obtained with other scanners by 0.4, the scanning accuracy was 95% (CI 1.3-1.9). The results obtained do not exceed the permissible probable error (p≤0,05).&#x0D; Conclusions. The density of adherence of all-curly inserts in the cavity that were scanned by the VT Dental scanner (Russia) tends to the maximum permissible taking into account the scanning error and in comparison with the world analogues of the scanning device.

Effect of titanium surface functionalization with bioactive glass on osseointegration: An experimental study in dogs.

The purpose of this study was to evaluate the effect of surface functionalization with bioactive glass BSF18 on the osseointegration of sandblasted and dual acid-etched surface (AE) implants. Forty Morse taper implants with an AE surface as controls (C) or with an AE surface functionalized with BSF18 (BF) were placed in the mandibles of 10 beagles. Implants were analyzed after 2 and 4weeks of healing. Implant stability quotient (ISQ) values were registered immediately after installation and prior to sacrifice. Samples were analyzed for bone-to-implant contact (BIC) and bone density (BD). The characterization of BF implants included surface roughness analysis with atomic force microscopy and contact angle (CA) analysis to evaluate wettability. Data were analyzed using two-way ANOVA followed by Tukey's test (p<0.05). Surface roughness was not affected by BF treatment. CA was lower in the BF group compared to the C group. No significant difference was observed in ISQ values between surfaces (p=0,231), irrespective of time. Significantly higher ISQ values were observed for both implants after 4weeks when compared with baseline (p=0.04). Significantly higher BIC (p=0.011) and BD (p=0.025) values were observed for the BF compared to the C group at 2weeks. Significantly higher BIC (p=0.030) and BD (p=0.015) values for the C group were observed at 4weeks compared to 2weeks. No significant difference was observed in the BF group between 2 and 4weeks. Implant functionalization with BSF18 improved the wettability of the implant surface; enhancing BIC and BD at 2weeks.

Microtubule Feedback and LET-99-Dependent Control of Pulling Forces Ensure Robust Spindle Position

During asymmetric division of the Caenorhabditis elegans zygote, to properly distribute cell fate determinants, the mitotic spindle is asymmetrically localized by a combination of centering and cortical-pulling microtubule-mediated forces, the dynamics of the latter being regulated by mitotic progression. Here, we show a, to our knowledge, novel and additional regulation of these forces by spindle position itself. For that, we observed the onset of transverse spindle oscillations, which reflects the burst of anaphase pulling forces. After delaying anaphase onset, we found that the position at which the spindle starts to oscillate was unchanged compared to control embryos and uncorrelated to anaphase onset. In mapping the cortical microtubule dynamics, we measured a steep increase in microtubule contact density after the posterior centrosome reached the critical position of 70% of embryo length, strongly suggesting the presence of a positional switch for spindle oscillations. Expanding a previous model based on a force-generator temporal control, we implemented this positional switch and observed that the large increase in microtubule density accounted for the pulling force burst. Thus, we propose that the spindle position influences the cortical availability of microtubules on which the active force generators, controlled by cell cycle progression, can pull. Importantly, we found that this positional control relies on the polarity-dependent LET-99 cortical band, the boundary of which could be probed by microtubules. This dual positional and temporal control well accounted for our observation that the oscillation onset position resists changes in cellular geometry and moderate variations in the active force generator number. Finally, our model suggests that spindle position at mitosis end is more sensitive to the polarity factor LET-99, which restricts the region of active force generators to a posterior-most region, than to microtubule number or force generator number/activity. Overall, we show that robustness in spindle positioning originates in cell mechanics rather than biochemical networks.

Calculation of contact densities and Mössbauer isomer shifts utilising the Dirac-exact two-component normalised elimination of the small component (2c-NESC) method

ABSTRACTUtilizing the analytic derivative formalism for the Mössbauer isomer shift in connection with the Dirac-exact two-component Normalized Elimination of the Small Component (2c-NESC) method a new approach to the analytic calculation of the contact densities at the nuclei has been developed and implemented in the general purpose NESC programme. The new approach is applied to the calculation of the contact densities as well as contact density differences in several iodine-, gold-, and mercury-containing molecules. Substantial differences between the contact densities obtained by the spin-free 1c-NESC method and the 2c-NESC method are found, which demonstrate the importance of spin-orbit coupling. However, the influence of spin-orbit coupling on the contact density differences between the sample and the reference nuclei is found to be modest. This result suggests that a low-cost determination of accurate contact densities at the nuclei can be achieved by combining the 1c-NESC densities obtained at the correlated wavefunction level of theory with the contact density differences obtained at the 2c-NESC/DFT level.

Prediction of Contact Angles and Density Profiles of Sessile Droplets Using Classical Density Functional Theory Based on the PCP-SAFT Equation of State.

This study demonstrates the capability of the density functional theory (DFT) formalism to predict contact angles and density profiles of model fluids and of real substances in good quantitative agreement with molecular simulations and experimental data. The DFT problem is written in cylindrical coordinates, and the solid-fluid interactions are defined as external potentials toward the fluid phase. Monte Carlo (MC) molecular simulations are conducted in order to assess the density profiles resulting from the Helmholtz energy functional used in the DFT formalism. Good quantitative agreement between DFT predictions and MC results for Lennard-Jones and ethane nanodroplets is observed, both for density profiles and for contact angles. That comparison suggests, first, that the Helmholtz energy functional proposed in a previous study [ Sauer , E. ; Gross , J. Ind. Eng. Chem. Res. 56 , 2017 , 4119 - 4135 ] is suitable for three-phase contact lines and, second, that Lagrange multipliers can be used to constrain the number of molecules, similar to a canonical ensemble. Experiments of sessile droplets on solid surfaces are performed to assess whether a real solid with its microscopic roughness can be described through a simple model potential. Comparison of DFT results to experimental data is done for a Teflon surface because Teflon can be regarded as a substrate exhibiting only attractive interactions of van der Waals type. It is shown that the real solid can be described as a perfectly planar solid with effective solvent-to-solid interactions, defined through a single adjustable parameter for the solid. Subsequent predictions for the contact angle of eight solvents, including polar components such as water, are found in very good agreement to experimental data using simple Berthelot-Lorentz combining rules. For the eight investigated solvents, we find mean absolute deviations of 3.77°.

Hole Transport in Low-Donor-Content Organic Solar Cells

Organic solar cells with an electron donor diluted in a fullerene matrix have a reduced density of donor-fullerene contacts, resulting in decreased free-carrier recombination and increased open-circuit voltages. However, the low donor concentration prevents the formation of percolation pathways for holes. Notwithstanding, high (>75%) external quantum efficiencies can be reached, suggesting an effective hole-transport mechanism. Here, we perform a systematic study of the hole mobilities of 18 donors, diluted at ∼6 mol % in C60, with varying frontier energy level offsets and relaxation energies. We find that hole transport between isolated donor molecules occurs by long-range tunneling through several fullerene molecules, with the hole mobilities being correlated to the relaxation energy of the donor. The transport mechanism presented in this study is of general relevance to bulk heterojunction organic solar cells where mixed phases of fullerene containing a small fraction of a donor material or vice versa are present as well.

Rapid and accurate characterization of silver-paste metallization on crystalline silicon solar cells by contact-end voltage measurement

Contact-end voltage measurement was applied to characterize the contact-formation process of silver paste metallization on p- and n-type crystalline silicon solar cells under different temperatures with well-designed fixtures and test patterns based on the circular transmission line model. The contact-end voltage values were found to be sensitive to sintering temperature, and the current density and contact end voltage curves of both contacts were linear, stating that the contacts were ohmic contacts. Their symbols on the n-type emitter reversed from negative to positive under the established connection mode, which indicated conductive-path changes manifested in the form of macroscopic electrical properties under insufficient, optimal, and over-fired conditions. We inferred that the conductive channel variations were mainly caused by the silver crystallites that precipitated on the emitter surface from the combination of the cross-sectional and interface morphology analyses. No similar phenomenon was observed on the p-type emitter for the few silver crystallites or silver-aluminum alloy without conductive-path alternation. Their values were much greater than those of the n-emitter, which agreed with the present industrial n-type cell characteristics. The measurement improved our understanding of the contact formation process, and can be used as a flexible approach for researchers to optimize the silver-paste formula and sintering processes for high-efficiency solar cells.

Prediction of Shear Transfer in High-strength Concrete Crack Interfaces

Shear behaviour of concrete is still a riddle, accurate prediction of concrete shear capacity is therefore a challenge. Shear transfers across concrete cracks primarily via aggregate interlocking based shear friction and via dowel action, amongst the former is considered as the major factor. It is found that the Contact Density Function (CDF) has the potential to quantify shear friction at cracked concrete interfaces. This function has mainly been used for normal strength concrete (NSC) (<60 MPa) and recent investigations show that it has to be modified when it is used for high strength concrete (HSC) , different aggregate sizes and large crack widths. The current study focussed on the modification of the CDF to suit high-strength concrete using the experimental results of nine pre-cracked push-off specimens which comprised of compressive strength up to 90 MPa, maximum aggregate sizes of 12.5/20 mm, and comparatively large initial crack width of about 0.5 mm. The results indicate a significant prediction inaccuracy when the existing model is used for HSC specimens. However, incorporation of a modification into the formulae is found to improve the prediction accuracy for HSC reasonably.

The effect of square-shaped pockets position in sliding line contacts under mixed regime of lubrication

The production of surface topography by artificial pockets is introduced as a well-known method to reduce friction and wear between conjugating surfaces under different lubrication regimes. As a result, the proper design and position of the pockets are of prime importance. This paper supports that goal and focuses on the contribution of the square-shaped textures in several inlet positions and densities on film thickness and wear of line contacts under mixed lubricated conditions. The applied load, the sliding speed, and the lubricant oil are set on a custom-built block-on-ring test rig. The lubricant film thickness is measured in real time using capacitive sensors. The wear behavior of the pocketed samples is also examined by an optical microscopy before and after the tests. The findings are compared by the results of similar studies. The results showed that using square-shaped pockets with high density in line contacts can pronounce film thickness up to 40% than the sparser pattern, which resulted in lowest level of abrasive wear. The position of the square-shaped pockets comprising the inlet lubricant flow is given a beneficial effect on starvation in line contacts, helping to lubricant replenishment into the contact.

Neurite architecture of the planum temporale predicts neurophysiological processing of auditory speech.

The left hemispheric advantage in speech perception is reflected in faster neurophysiological processing. On the basis of postmortem data, it has been suggested that asymmetries in the organization of the intrinsic microcircuitry of the posterior temporal lobe may produce this leftward timing advantage. However, whether this hypothetical structure-function relationship exists in vivo has never been empirically validated. To test this assumption, we used in vivo neurite orientation dispersion and density imaging to quantify microcircuitry in terms of axon and dendrite complexity of the left and right planum temporale in 98 individuals. We found that a higher density of dendrites and axons in the temporal speech area is associated with faster neurophysiological processing of auditory speech, as reflected by electroencephalography. Our results imply that a higher density and higher number of synaptic contacts in the left posterior temporal lobe increase temporal precision and decrease latency of neurophysiological processes in this brain region.

Effect of High-Density Electric Current on Wear and Average Temperature of Steel/Steel Triboelectric Contact

In this paper, we presented studies of the sliding friction without lubrication of Hadfield steel, ShKh15 bearing steel, and AISI steel 1020 against AISI steel 1045 upon applying an electric current with a contact density higher 100 A/cm2. We showed that the intensity of the surface layer deterioration increased with increasing current density. The catastrophic wear of materials begins at different values of the current density and at close values of the wear energy intensity. The dependences of the average contact temperatures on the current have been determined. The major conclusion is that it is impractical to harden the primary structure by alloys to achieve a low wear rate.

A Novel µECoG Electrode Interface for Comparison of Local and Common Averaged Referenced Signals.

Micro-electrocorticography (µECoG) is a minimally invasive neural interface that allows for recording from the surface of the brain with high spatial and temporal resolution [1], [2]. However, discerning multi-unit and local field potential (LFP) activity with potentially highly-correlated signals across a dense µECoG array can be challenging. Here we describe a novel µECoG design to compare the effect of referencing recordings to a local reference electrode and common average referencing (CAR). The filtering effect and the significant increase in signal to noise ratio of the evoked response (ESNR) can be seen after re-referencing for both types of referencing. In a preliminary analysis, re-referencing the µECoG signals can increase recording performance at high contact densities in the auditory cortex. This also provides promising evidence for a versatile in-house fabricated µECoG electrode.

Low Cell-Matrix Adhesion Reveals Two Subtypes of Human Pluripotent Stem Cells

SummaryWe show that a human pluripotent stem cell (hPSC) population cultured on a low-adhesion substrate developed two hPSC subtypes with different colony morphologies: flat and domed. Notably, the dome-like cells showed higher active proliferation capacity and increased several pluripotent genes’ expression compared with the flat monolayer cells. We further demonstrated that cell-matrix adhesion mediates the interaction between cell morphology and expression of KLF4 and KLF5 through a serum response factor (SRF)-based regulatory double loop. Our results provide a mechanistic view on the coupling among adhesion, stem cell morphology, and pluripotency, shedding light on the critical role of cell-matrix adhesion in the induction and maintenance of hPSC.