Search

Low-temperature, low-pressure Cu-to-Cu direct bonding technology is a promising solution for next-generation high-density interconnects. Previous studies have shown that many properties of nanomaterials are determined by their structural characteristics. Therefore, the effect of the nanostructure (i.e., twin crystal and twin boundary, TB, sizes) on the bonding mechanism and mechanical response of the direct bonding of (111)-oriented nanotwinned Cu (NT-Cu) is studied using molecular dynamics simulations, where TB size means the TB layer thickness in terms of the number of atoms. The simulation results show that NT-Cu with extremely small twin crystals (e.g., 0.625 nm) have poor diffusivity. The number of dislocations induced by plastic deformation increases with increasing twin crystal size during stretching processes, degrading mechanical strength. The strain hardening of bonded NT-Cu with extremely small twin crystals (e.g., 0.625 nm) is dominated by the strong barrier created by a high density of TBs, whereas that with twin crystal sizes of 2.5–10 nm is dominated by dislocation–TB and dislocation–grain boundary interactions. Bonded NT-Cu with 2–6 atoms per TB layer exhibits softening at initial plastic deformation due to the onset of partial collapse of TBs; however, the strength then significantly increases with a further increase in strain due to strain hardening. [ABSTRACT FROM AUTHOR]

Alloying nanocrystalline Cu (nc–Cu) with immiscible elements (i.e. Zr) is a promising approach for reducing microstructural instability and inhibiting grain growth. Understanding the relationship between the grain size, Zr concentration, deformation, and mechanical properties of the nc–Cu–Zr system is essential for practical applications. Molecular dynamics simulations based on the many-body embedded-atom potential were used for the related analysis from an atomistic point of view. The grain size of nc–Cu was varied from 3 to 9 nm and the Zr concentration was varied from 0% to 7%. The simulation results show that doping Zr atoms into an nc–Cu system enhances tensile strength and ductility, but weakens compressive and shear strengths. Doping 1% Zr into nc–Cu greatly increases both ultimate tensile strength and ultimate tensile strain; the increase is insignificant for higher Zr concentrations (2% to 7%). For a given Zr concentration, the relationship between ultimate tensile strength and grain size is unclear. Grain boundary sliding dominates the elastic deformation mechanism of the nc–Cu–Zr system under tensile, compressive, and shear tests. Tensile fracture occurs faster for an nc–Cu–Zr system with a larger grain size. [ABSTRACT FROM AUTHOR]

Context: Diamond-like carbon (DLC) films are amorphous solids in which carbon atoms are linked by hybridized sp3, sp2, and sp bonds. The mechanical and tribological properties of DLC films can be adjusted by tuning the sp2/sp3 bond ratio. These films are typically used as protective coatings for components such as dies, automotive engines, mechanical seals, hard disk drives, biological engineering devices, and micro/nano-electromechanical systems. Further exploration of the mechanical and tribological behavior of DLC films is important for enhancing functional design for the above applications. The simulation results show that single-layer DLC with a higher sp3 ratio has better resistance to indentation. Single-layer DLC with a lower initial sp3 ratio has lower friction and a shorter repeated cycle in the friction force curve due to an increase in the graphitization of the friction interface. Single-layer DLC with a higher sp3 ratio has a higher coefficient of friction because compared with the normal force, the friction force is much more sensitive to an increase in the sp3 ratio. Methods: Molecular dynamics simulations based on the Tersoff potential were performed using the open-source code LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). [ABSTRACT FROM AUTHOR]

The effects of heating rate during the thermal coarsening of nanoporous gold (NPG) on its morphological evolution, microstructure, and mechanical properties are studied using molecular dynamics simulations. The simulation results show that lower heating rates promote the coarsening of NPG and decreasing porosity. The coarsening proceeds until the end of the heating process, followed by structural relaxation and recovery of the crystalline structure during the cooling process. NPG coarsened at lower heating rates has better mechanical strength. NPG under compression has a much higher dislocation density than that under tension, which results in a significant tension/compression asymmetry. During compression, NPG necking preferentially occurs at smaller ligament junctions and the orientation is [110]. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC) films, which are generally used in the form of protective coatings, have a lot of engineering applications, where they improve surface friction, adhesion, and wear resistance. Hence, it is necessary to understand the correlation between DLC coating parameters and the mechanical properties. The effects of sp3 bond and modulation ratios of DLC coatings on the deformation and mechanical properties are studied using molecular dynamics (MD) nanoindentation simulations. MD simulations allow the analyses of the mechanical deformation and mechanics of nanosystems. The in situ material degradation and local deformation of DLC coatings are examined during nanoindentation. The simulation results show that single-layer DLC with a higher initial sp3 ratio generally has a larger indentation force (higher resistance to indentation), a smaller influence area, and a larger residual depth after unloading. With an increase in initial sp3 ratio, the sp3-sp2 bonding transition of C atoms significantly increases at stages of loading, holding, and unloading. Amorphous carbon/tetrahedral amorphous carbon (a-C/ta-C) bilayers with a smaller modulation ratio and ta-C/a-C bilayers with a larger modulation ratio generally require a larger indentation force. Bilayers have poor overall support when the soft (a-C) layer is the bottom layer, which increases the influence area. [ABSTRACT FROM AUTHOR]

The effects of Zr solute and loading mode on the structure, mechanics, and mechanical properties of nanocrystalline (NC)-Cu are studied using molecular dynamics simulations. Doping Zr atoms into NC-Cu systems stabilizes grain boundaries, suppresses dislocation nucleation and propagation, and increases the elastic deformation phase during tensile, compressive, and shear deformation processes. The tensile and shear strengths of NC-Cu/Zr systems are maximum at Zr concentrations of 5% and 3%, respectively. Young's modulus and mechanical strength of NC-Cu/Zr systems under compression both decrease with increasing Zr concentration. Grain boundary sliding dominates shear deformation and induces dislocation activity. [ABSTRACT FROM AUTHOR]

The effects of extrusion temperature and velocity on extruded gold nanowires (NWs) are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effects are investigated in terms of atomic trajectories, common neighbor analysis, flow field, and the extruded NW length-pressing ram displacement curve. The simulation results show that NWs extruded at a temperature of 300 K are longer and have a more uniform cross-sectional area compared to those extruded at higher temperatures. Higher temperature increases the cross-sectional area of extruded NWs, whereas higher extrusion velocity decreases it. In the extrusion process, dislocations first nucleate around the mold outlet and propagate along the close-packed plane {111} toward the interior. The number of disordered structures significantly increases with increasing extrusion temperature and velocity. [ABSTRACT FROM AUTHOR]

Context: Nanoporous metals (NPMs) have a three-dimensional bicontinuous porous network structure that consists of interconnected nanoligaments. NPMs have the potential to effectively attenuate and dissipate the effects of impacts and blasts. Previous studies do not provide data on the possible effects of porosity at the nanoscale. Methods: Molecular dynamics simulations based on the embedded-atom method potential were performed using the open-source code LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). Results: Nanoporous gold (NPG) absorbs shock energy first through the elastic-plastic deformation of ligaments and then through the collapse of ligaments. After the shock loading is relaxed, NPG with lower porosity has a higher amount of springback, and new voids tend to nucleate and grow at collapsed ligaments where the packing is looser. NPG with higher porosity has a better ability to resist the propagation of a shock wave and is subjected to a smaller stress effect. [ABSTRACT FROM AUTHOR]

The effects of the location and size of Kirkendall voids at the nanoscale on the mechanical response of a Cu/Sn solder joint under a tension test are studied using molecular dynamics simulations. The simulation results show that the ultimate stress and ultimate strain of a solder joint with two pre-existing voids decrease with increasing void radius regardless of the distance (L2) between the centre of void 2 and the interface when the distance (L1) for void 1 is 4 nm. The elastic deformation period of the solder joint shortens with increasing void radius for void radii ≥3 nm. At the end of the tensile test, a collapse occurs at the layer interface when the two pre-existing voids are very small (e.g. void radius = 1 nm) regardless of the L2 value. For two pre-existing voids with different radii, cracks at the interface grow toward the larger void and then merge with it when the two voids are close to the interface (e.g. L1 = L2 = 4 nm). Fracture occurs at the pre-existing voids when the two voids have large radii (e.g. 4 nm) and are very close to each other. [ABSTRACT FROM AUTHOR]

Background:. Up to 20% of people with HIV (PWH) who undergo virologically suppressed antiretroviral therapy (ART) fail to experience complete immune restoration. We recently reported that plasma anti-CD4 IgG (antiCD4IgG) autoantibodies from immune non-responders specifically deplete CD4 + T cells via antibody-dependent cytotoxicity. However, the mechanism of antiCD4IgG production remains unclear. Methods:. Blood samples were collected from 16 healthy individuals and 25 PWH on suppressive ART. IgG subclass, plasma lipopolysaccharide (LPS), and antiCD4IgG levels were measured by ELISA. Gene profiles in B cells were analyzed by microarray and quantitative PCR. Furthermore, a patient-derived antiCD4IgG–producing B cell line was generated and stimulated with LPS in vitro. B cell IgG class switch recombination (CSR) was evaluated in response to LPS in splenic B cells from C57/B6 mice in vitro. Results:. Increased plasma anti-CD4 IgGs in PWH were predominantly IgG1 and associated with increased plasma LPS levels as well as B cell expression of TLR2, TLR4, and MyD88 mRNA in vivo. Furthermore, LPS stimulation induced antiCD4IgG production in the antiCD4IgG B cell line in vitro. Finally, LPS promoted CSR in vitro. Conclusion:. Our findings suggest that persistent LPS translocation may promote anti-CD4 autoreactive B cell activation and antiCD4IgG production in PWH on ART, which may contribute to gradual CD4 + T cell depletion. This study suggests that reversing a compromised mucosal barrier could improve ART outcomes in PWH who fail to experience complete immune restoration. [ABSTRACT FROM AUTHOR]

The effects of a Kirkendall void at the nanoscale on the mechanical behavior of a Cu/Cu3Sn solder interface under shear and tensile tests, respectively, are studied using molecular dynamics simulations. The simulation results show that for a solder interface without a Kirkendall void under tension, fracture is induced by a collapse of the interface, and that for a solder interface without a Kirkendall void under shearing, plastic deformation is dominated by shear bands. A shear band propagates through a small void (radius ≤ 3 nm) but is stopped by a large void (radius = 4 nm) or neighboring dislocations. For a solder interface with a Kirkendall void under tension, a collapse of the solder interface occurs faster with increasing void radius. When the void is far away from the solder interface, fracture is dominated by a competition between a collapse of the solder interface and void deformation and growth. A solder interface has the maximum shear and tensile strength when a pre-existing void (radius = 1 nm) locates at the interface. For a solder interface with a Kirkendall void, the ultimate shear stress, tensile stress, and tensile strain decrease with increasing initial void radius. [ABSTRACT FROM AUTHOR]

We recently reveal that anti-CD4 autoantibodies contribute to blunted CD4+ T cell reconstitution in HIV+ individuals on antiretroviral therapy (ART). Cocaine use is common among HIV+ individuals and is associated with accelerated disease progression. However, the mechanisms underlying cocaine-induced immune perturbations remain obscure. We evaluated plasma levels of anti-CD4 IgG and markers of microbial translocation, as well as B-cell gene expression profiles and activation in HIV+ chronic cocaine users and non-users on suppressive ART, as well as uninfected controls. Plasma purified anti-CD4 IgGs were assessed for antibody-dependent cytotoxicity (ADCC). HIV+ cocaine users had increased plasma levels of anti-CD4 IgGs, lipopolysaccharide (LPS), and soluble CD14 (sCD14) versus non-users. An inverse correlation was observed in cocaine users, but not non-drug users. Anti-CD4 IgGs from HIV+ cocaine users mediated CD4+ T cell death through ADCC in vitro. B cells from HIV+ cocaine users exhibited activation signaling pathways and activation (cycling and TLR4 expression) related to microbial translocation versus non-users. This study improves our understanding of cocaine associated B cell perturbations and immune failure and the new appreciation for autoreactive B cells as novel therapeutic targets. [ABSTRACT FROM AUTHOR]

The effect of temperature on the structural evolution of nanocrystalline (NC) and single-crystalline (SC) Au nanowires (NWs) under torsional deformation is studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effect is investigated using common neighbor analysis and discussed in terms of shear strain distribution and atomic flow field. The simulation results show that deformation for NC NWs is mainly driven by the nucleation and propagation of dislocations and the gliding of grain boundaries (GBs) and that for SC NWs is mainly driven by dislocations and the formation of disordered structures. Dislocations for NC and SC NWs easily nucleate at GBs and free surfaces, respectively. For NC NWs, torsional buckling occurs easily at GBs with large gliding. SC NWs have a more uniform and larger elastic deformation under torsion compared to that for NC NWs due to the former's lack of grains. SC NWs have a long period of elastic deformation transforming into plastic deformation. Increasing temperature facilitates stress transmission throughout NWs. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular management and risk stratification of patients is an important issue in clinics. Patients who have experienced an adverse cardiac event are concerned for their future and want to know the survival probability. Methods: We trained eight state-of-the-art CNN models using polar maps of myocardial perfusion imaging (MPI), gender, lung/heart ratio, and patient age for 5-year survival prediction after an adverse cardiac event based on a cohort of 862 patients who had experienced adverse cardiac events and stress/rest MPIs. The CNN model outcome is to predict a patient's survival 5 years after a cardiac event, i.e., two classes, either yes or no. Results: The best accuracy of all the CNN prediction models was 0.70 (median value), which resulted from ResNet-50V2, using image as the input in the baseline experiment. All the CNN models had better performance after using frequency spectra as the input. The accuracy increment was about 7~9%. Conclusions: This is the first trial to use pure rest/stress MPI polar maps and limited clinical data to predict patients' 5-year survival based on CNN models and deep learning. The study shows the feasibility of using frequency spectra rather than images, which might increase the performance of CNNs. [ABSTRACT FROM AUTHOR]

We prove the existence of immersed closed curves of constant geodesic curvature in an arbitrary Riemannian 2-sphere for almost every prescribed curvature. To achieve this, we develop a min-max scheme for a weighted length functional. [ABSTRACT FROM AUTHOR]

Hepatic fibrosis is a common pathological process involving persistent liver injury with various etiologies and subsequent inflammatory responses that occur in chronic liver diseases. If left untreated, liver fibrosis can progress to liver cirrhosis, hepatocellular carcinoma and eventually, liver failure. Unfortunately, to date, there is no effective treatment for liver fibrosis, with the exception of liver transplantation. Although the pathophysiology of liver fibrosis is multifactorial and includes the activation of hepatic stellate cells, which are known to drive liver fibrogenesis, hepatic macrophages have emerged as central players in the development of liver fibrosis and regression. Hepatic macrophages, which consist of resident macrophages (Kupffer cells) and monocyte‐derived macrophages, have been shown to play an intricate role in the initiation of inflammatory responses to liver injury, progression of fibrosis, and promotion of fibrosis resolution. These features have made hepatic macrophages uniquely attractive therapeutic targets in the fight against hepatic fibrosis. In this review, we synthesised the literature to highlight the functions and regulation of heterogeneity in hepatic macrophages. Furthermore, using the existing findings, we attempt to offer insights into the molecular mechanisms underlying the phenotypic switch from fibrogenic macrophages to restorative macrophages, the regulation of heterogeneity, and modes of action for hepatic macrophages. A better understanding of these mechanisms may guide the development of novel anti‐fibrotic therapies (eg macrophage subset‐targeted treatments) to combat liver fibrosis in the future. [ABSTRACT FROM AUTHOR]

Emerging resistive random access memory (RRAM) has shown the great potential of in-memory processing capability, and thus attracts considerable research interests in accelerating memory-intensive applications, such as neural networks (NNs). However, the accuracy of RRAM-based NN computing can degrade significantly, due to the intrinsic statistical variations of the resistance of RRAM cells. In this article, we propose SIGHT, a synergistic algorithm-architecture fault-tolerant framework, to holistically address this issue. Specifically, we consider three major types of faults for RRAM computing: 1) nonlinear resistance distribution; 2) static variation; and 3) dynamic variation. From the algorithm level, we propose a resistance-aware quantization to compel the NN parameters to follow the exact nonlinear resistance distribution as RRAM, and introduce an input regulation technique to compensate for RRAM variations. We also propose a selective weight refreshing scheme to address the dynamic variation issue that occurs at runtime. From the architecture level, we propose a general and low-cost architecture accordingly for supporting our fault-tolerant scheme. Our evaluation demonstrates almost no accuracy loss for our three fault-tolerant algorithms, and the proposed SIGHT architecture incurs performance overhead as little as 7.14%. [ABSTRACT FROM AUTHOR]

The effects of tool rake angle and workpiece surface roughness on the cutting mechanism and mechanics of Cu are studied using quasi-continuum simulations. These effects are investigated in terms of atomic trajectories, stress distribution, cutting force, resistance factor, and cutting ratio. The simulation results show that negative rake angles lead to a larger cutting force, lower resistance coefficient, and higher cutting ratio than those obtained with positive rake angles. For tools with an initial rake angle of 2° to 8°, the rake angle becomes negative during the cutting process due to the strong adhesion interaction between the tool rake face and chips. The resistance coefficient decreases with increasing tool rake angle for rake angles in the range of 2° to 8°. Tools with negative rake angles of −2° to −8° have similar cutting ratios. The cutting ratio decreases and cutting force increases with increasing surface roughness of the workpiece. [ABSTRACT FROM AUTHOR]

The mechanism and quality of the welding of single-crystal (SC) and amorphous gold nanowires (NWs) with head-to-head contact are studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. The results are discussed in terms of atomic trajectories, slip vectors, stress, and radial distribution function. Simulation results show that the alignment for the amorphous NWs during welding is easier than that for the SC NWs due to the former's relatively stable geometry. A few dislocations nucleate and propagate on the (111) close-packed plane (slip plane) inside the SC NWs during the welding and stretching processes. During welding, an incomplete jointing area first forms through the interactions of the van der Waals attractive force, and the jointing area increases with increasing extent of contact between the two NWs. A crystallization transition region forms in the jointing area for the welding of SC-amorphous or amorphous-SC NWs. With increasing interference, an amorphous gold NW shortens more than does a SC gold NW due to the former's relatively poor strength. The pressure required for welding decreases with increasing temperature. [ABSTRACT FROM AUTHOR]

People infected with chronic hepatitis B virus (HBV) might progress to acute-on-chronic liver failure (ACLF) with a high fatality rate. Long noncoding RNAs (lncRNAs) are involved in human diseases, but it is unknown whether lncRNAs are involved in the progression of chronic HBV infection to ACLF. Hence, this study is aimed at systemically identifying and characterizing the landscape and the molecular mechanism of lncRNAs in the pathogenesis of chronic HBV infection progress to ACLF. RNA sequencing (RNA-Seq) of peripheral blood samples from 5 ACLF and 5 HBV infection patients was performed. We detected 9733 lncRNAs, including 406 annotated lncRNAs and 9327 novel lncRNAs. A total of 407 lncRNAs were found to be significantly dysregulated in the patients with ACLF as compared with those in the chronic HBV infection patients. The flanking protein-coding genes of differentially expressed lncRNAs were enriched with pathways that might contribute to the pathogenesis of ACLF, such as the WNT signaling pathway. Furthermore, 9 selected differentially expressed lncRNAs validated by the qRT-PCR, showing that the expression patterns of these 9 lncRNAs were consistent with the RNA-Seq data. Four selected differentially expressed lncRNAs were also validated in another patient cohort comprising 80 patients with ACLF and 65 patients with chronic HBV infection. Aberrant lncRNAs might be used to develop novel diagnostic biomarkers or drug targets for ACLF. [ABSTRACT FROM AUTHOR]

The effects of the bonding temperature and interference amount (extent of contact between two Cu microbumps during the bonding process) on the bonding mechanism and mechanical behavior of Cu-to-Cu direct bonding using (111)-oriented nanotwinned Cu (NT-Cu) have been studied using molecular dynamics simulations. The simulation results show that two NT-Cu microbumps gradually bond and the interface voids eliminated via atomic diffusion during the bonding and holding processes. NT-Cu bonded at higher temperature has more randomly distributed disordered atoms and fewer remaining grain boundaries. Few cracks directly nucleate at the bonding interface of bonded NT-Cu during stretching for various bonding temperatures and interference amounts, indicating the good bonding quality. Bonding at temperatures in the range of 300–623 K with an interference value of 0 nm generally lead to higher yield strength and lower yield strain and ultimate strength and strain than those of raw NT-Cu. In addition, bonding at higher temperature leads to better ductility at room temperature. The yield strain and ultimate strength and strain for bonded NT-Cu obtained at 423 K with an interference value of 0 nm can be significantly improved upon increasing the interference value. • NT-Cu bonded at higher temperature has more randomly distributed disordered atoms and fewer remaining grain boundaries. • Few cracks directly nucleate at the bonding interface of bonded NT-Cu during stretching, indicating good bonding quality. • Bonding at higher temperature leads to better ductility at room temperature. [ABSTRACT FROM AUTHOR]

The effects of microstructure and loading mode on the mechanical properties of Au nanowires (NWs) are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effects are investigated in terms of common neighbour analysis, shear strain distribution, and stress-strain curves. The microstructure effect is examined using single-crystalline (SC), nanocrystalline (NC), and amorphous (AC) structures. The simulation results show that during tension, SC, NC, and AC NWs have visually similar deformations and similar ultimate strains, but completely different deformation mechanisms. For all loading modes, the SC NWs have the highest tensile and shear strength values and the NC NWs have the highest compressive strength. The AC NWs have poor strength under tensile, compressive, and shear loadings. The presence of grain boundaries increases the geometric instability of the NC NWs under compression and shear loadings. [ABSTRACT FROM AUTHOR]

The effects of the constituting material and an interfacial crack on the deformation and mechanical response of metallic bilayer films under tension are studied using quasi-continuum simulations in terms of atomic trajectories, stress distribution and the stress–strain curve. The simulation results show that bilayer films with identical constituting monolayers have higher tensile strength than that of those with different monolayers. For bilayer films with different monolayers, the layer interface acts as a barrier that resists dislocation propagation. Dislocation emission at a crack tip blunts the tip. Necking originates at the layer interface and develops on monolayers with relatively low strength. A rectangular crack is less likely to develop than a V-shaped crack. [ABSTRACT FROM AUTHOR]

The effect of pore size on the deformation mechanism and mechanical properties of nanoporous Ni under tension and compression tests is studied using molecular dynamic simulations in terms of atomic trajectories, dislocation extraction algorithm, and the stress–strain curve. The simulation results show that samples have a longer elastic deformation period during tension compared to that during compression. Dislocations nucleate at pore surfaces and propagate until they are terminated by neighboring pores. Samples under tension have lower ultimate stress and higher strain at ultimate stress compared to those of samples under compression. Samples with smaller pore diameter have more transformation from face-centered cubic to hexagonal close-packed structures due to more dislocation activity. The ultimate stress of samples significantly decreases with increasing pore diameter. [ABSTRACT FROM AUTHOR]

The effects of alloy composition, cavity aspect ratio, and temperature on the pattern transfer mechanism and mechanics of ZrCu metallic glass (MG) films under a nanoimprinting process are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The simulation results show that the glass transition temperature of ZrCu MGs increases with increasing Zr content. Imprinting at higher temperatures or with a higher cavity aspect ratio shortens filling time. Shear origin zones are more concentrated for imprinting at lower imprint temperatures or a higher cavity aspect ratio. The loading force increases with increasing cavity aspect ratio and decreasing Zr content. The springback ratio of a pattern increases with increasing cavity aspect ratio and decreasing Zr contare the film heights including and ent. For imprinting with a high cavity aspect ratio, the pattern width has much more springback than that of the pattern height. The sharpness of patterns significantly decreases with increasing unloading temperature. [ABSTRACT FROM AUTHOR]

This study aims explore the feasibility of using neural network (NNs) and deep learning to diagnose three common respiratory diseases with few symptom words. These three diseases are nasopharyngitis, upper respiratory infection, and bronchitis/bronchiolitis. Through natural language processing, the symptom word vectors are encoded by GPT-2 and classified by the last linear layer of the NN. The experimental results are promising, showing that this model achieves a high performance in predicting all three diseases. They revealed 90% accuracy, which suggests the implications of the developed model, highlighting its potential use in assisting patients' understanding of their conditions via a remote diagnosis. Unlike previous studies that have focused on extracting various categories of information from medical records, this study directly extracts sequential features from unstructured text data, reducing the effort required for data pre-processing. [ABSTRACT FROM AUTHOR]

The concept of the OOS of spacecraft can be traced back to the 1960s, when the main focus was on providing the necessary maintenance to advance the lifetime of spacecraft and extending the scale and function through on-orbit assembly. During the past decades, the Hubble Space Telescope has made great contributions to the fields of astronomy and physics through both observational data and the success of five OOS missions to overcome big challenges. That included an initial flaw of its primary mirror and subsequent obstacles associated with replacing and upgrading its science instruments. Furthermore, many programs have been carried out in the area of the OOS of spacecraft with successful operations in space. It could be exemplified by the assembly of the International Space Station, service verification of ETS-VII and Orbital Express, and detailed research for future applications including servicer and client satellites and particularly large space systems. This paper attempts to summarize all reported programs of the OOS in terms of engineering developments and provide an overall perspective for investigators in this field. Based on the reviewed programs, an analysis is carried out to elucidate the logical architectures of the mission and technology of the OOS of spacecraft. Further attention is paid to discussions of the enabling technologies that support the development of the OOS and related spacecraft. As an outlook, the future development and challenges of the OOS and the application of novel technologies are finally discussed to extend the present review work. [ABSTRACT FROM AUTHOR]

Abstract TLR21 can recognize unmethylated cytosine-phosphate-guanine oligodeoxynucleotides (CpG-ODN) and activates NF-κB immune signaling pathway. However, the function of TLR21 in duck remains largely unclear. Here, the complete duck TLR21 (duTLR21) cDNA was cloned from Cherry Valley duck for the first time, and its immune response was preliminarily studied. Tissue specificity analysis showed duTLR21 was higher expressed in the peripheral blood, spleen, bursa of Fabricius and cecum. The expression of duTLR21 was significantly upregulated after stimulation with CpG-ODN or duck plague virus (DPV), but not Tembusu virus (TMUV), LPS or Poly (I:C). In addition, the transfection of DEF with duTLR21 stimulated by CpG-ODN activated NF-κB, through this signal pathway, the transcription of IL-1β, IL-6 and IFN-α were promoted, whereas knockdown of duTLR21 impaired the transcription of these genes. Furthermore, the overexpression of duTLR21 inhibited the replication of the DPV and the knockdown of duTLR21 by shRNA significantly promoted DPV replication in vitro. Altogether, these results indicate that duTLR21 can be activated by CpG-ODN, which mediates activation of NF-κB signaling pathway, and plays an important role in the host defence of DPV infection. [ABSTRACT FROM AUTHOR]

We have grown high-quality InxGa1-xN/GaN triple-quantum-well microdisks on LiAlO2 substrate by plasma-assisted molecular beam epitaxy. The InxGa1-xN/GaN microdisk with a hexagonal shape of oblique face 28o-angle off c-axis was achieved. The mechanism of the termination of awl-shaped growth and the growth rates of GaN-barrier and InxGa1-xN-well were evaluated and confirmed with the triple quantum wells. Based on the growth rates and 28o-angle geometric shape, one can control the finite size of InGaN/GaN microdisks by plasma-assisted molecular beam epitaxy. [ABSTRACT FROM AUTHOR]

The effects of surface notches and loading mode on the mechanical deformation and mechanics of ZrNi metallic glass (MG) are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effects are investigated in terms of atomic trajectories, shear strain distributions, and stress-strain curves. The simulation results show that for ZrNi MG, resistance to shear deformation (shear strain > 200%) before breaking is much greater than that to tensile and compressive deformation. For ZrNi MG under tension, a pre-existing notch leads to earlier necking and breaking. Significant stress concentration occurs around the notch root when the notch length (L) is 3 nm or above, and dominates plastic deformation. For ZrNi MG under compression, a pre-existing notch is completely filled by neighboring atoms at the initial stage of compression. A pre-existing notch leads to single-edge barreling and weakens a sample’s ultimate strength when the L value is 3 nm or above. For ZrNi MG under shear loading, a pre-existing notch does not influence the shear modulus of samples; however, their ultimate strength decreases with increasing L value. [ABSTRACT FROM AUTHOR]

A 12-T twin-aperture subscale dipole magnet is being developed for SPPC pre-study at the Institute of High Energy Physics (IHEP). The magnet is comprised of 6 double-pancake coils which include 2 Nb 3 Sn coils and 4 NbTi coils. As the stored energy of the magnet is 0.452 MJ and the operation margin is only about 20% at 4.2 K, a quick and effective quench protection system is necessary during the test of this high field magnet. For the design of the quench protection system, attention was not only paid to the hotspot temperature and terminal voltage, but also the temperature gradient during the quench process due to the poor mechanical characteristics of the Nb 3 Sn cables. With the adiabatic analysis, numerical simulation and the finite element simulation, an optimized protection method is adopted, which contains a dump resistor and quench heaters. In this paper, the results of adiabatic analysis and quench simulation, such as current decay, hot-spot temperature and terminal voltage are presented in details. [ABSTRACT FROM AUTHOR]

The effects of mold cavity geometry and imprinting temperature on imprinted amorphous ZrCu films are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effects are investigated in terms of shear strain, flow field, loading force, relationship between pattern filling height and mold displacement, and pattern elastic recovery. The simulation results show that imprinting should be conducted at high temperatures (slightly above the glass transition temperature), followed by unloading at 300 K. Imprinting at higher temperatures shortens the pattern filling time, decreases the required loading force, and lowers the shear strain concentration inside the films. Unloading at 300 K leads to a low pattern elastic recovery, which increases with increasing temperature. Imprinting using a groove pattern on the mold requires a larger loading force and less filling time compared to those required when using a tip-like pattern on the mold. For imprinting using a tip-like pattern on the mold at temperatures of 300–475 K, shear transformation zones form inside the films in the form of a ring surrounding the mold. [ABSTRACT FROM AUTHOR]

The effects of temperature and tensile velocity on the mechanical properties and mechanics of Au/Cu/Au/Cu nanofilms under tensile testing are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The simulation results show that at the initial tensile deformation, dislocations nucleate at layer interfaces, propagate along close-packed plane {111} toward the interior of the film, and are then terminated by layer interfaces, which act as a barrier. The proportions of atoms in face-centered cubic and hexagonal close-packed structures during tensile deformation decrease and that in other structures (disordered atoms) increases when the temperature increases from 273 to 700 K. Breaking occurs at layer interfaces at higher temperatures or tensile velocities, indicating that the interface is the weakest structure in the films. Breaking occurs earlier when a higher tensile velocity is used. The mechanical strength of the films increases with decreasing temperature and increasing tensile velocity. [ABSTRACT FROM AUTHOR]

Conduction cooled current leads, which bring the current from the room temperature terminal down to the cryogenic environment, were used in common recently in large scale superconducting accelerators for its low cost, sample design and low heat load. In practice, the current lead is designed contained in a stainless steel tube. The heat load can be incepted in steps by thermal anchors, where one end is attached to the stainless steel tube, while the other end is connected with the cold shield of the cryomodule. Since the limitation of the welding technique, a thicker stainless steel tube needs to be used, and hence the thermal anchors cannot provide enough pressure to deform the tube enough to be in direct contact with the current lead, which may lead to temperature instability and bring extra heat load to the cryogenic system. An excellent option of epoxy filled current lead can realize the fully contact and reduce the heat load effectively. This paper will present the process of the current lead design, optimization, numerical simulation and cryogenic test, the test results show that the current lead can keep in a stable operation and low heat load. [ABSTRACT FROM AUTHOR]

In an attempt to study the effect of heat treatment on hygroscopicity and durability of wood, Poplar ( Populus spp.) wood was thermally modified using five different temperatures between 170 °C and 210 °C, for a fixed duration of 3 h. Moisture adsorption behavior and the resistance to soft rot fungi were investigated thereafter. Based on the Hailwood-Horrobin sorption model, the amount of available sorption sites within specimens for the different groups of Poplar wood were calculated from the model’s m 0 parameter. Chemical analysis of the changes in wood components induced by heat treatment allows for a comparison between the easily obtained m 0 and the results of time-consuming wood decay tests. The proposed m 0 -based method for highly efficient evaluation and prediction of durability of thermally modified wood could optimize future research on the mechanisms of heat treatment processes. [ABSTRACT FROM AUTHOR]

Objective: Analysis of the crosslink time, depth and efficacy profiles of UV-light-activated corneal collagen crosslinking (CXL). Methods: A modeling system described by a coupled dynamic equations are numerically solved and analytic formulas are derived for the crosslinking time (T*) and crosslinking depth (z*). The z-dependence of the CXL efficacy is numerically produced to show the factors characterizing the profiles. Results: Optimal crosslink depth (z*) and maximal CXL efficacy (Ceff) have opposite trend with respective to the UV light intensity and RF concentration, where z* is a decreasing function of the riboflavin concentration (C0). In comparison, Ceff is an increasing function of C0 and the UV exposure time (for a fixed UV dose), but it is a decreasing function of the UV light intensity. CXL efficacy is a nonlinear increasing function of [C0/I0]-0.5 and more accurate than that of the linear theory of Bunsen Roscoe law. Depending on the UV exposure time and depth, the optimal intensity ranges from 3 to 30 mW/cm2 for maximal CXL efficacy. For steady state (with long exposure time), low intensity always achieves high efficacy than that of high intensity, when same dose is applied on the cornea. Conclusions: The crosslinking depth (z*) and the crosslinking time (T*) have nonlinear dependence on the UV light dose and the efficacy of corneal collagen crosslinking should be characterized by both z* and the efficacy profiles. A nonlinear scaling law is needed for more accurate protocol. [ABSTRACT FROM AUTHOR]

The effects of cutting depth, tool nose radius, and temperature on the cutting mechanism and mechanics of amorphous NiAl workpieces are studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. These effects are investigated in terms of atomic trajectories and flow field, shear strain, cutting force, resistance factor, cutting ratio, and pile-up characteristics. The simulation results show that a nanoscale chip with a shear plane of 135° is extruded by the tool from a workpiece surface during the cutting process. The workpiece atoms underneath the tool flow upward due to the adhesion force and elastic recovery. The required tangential force and normal force increase with increasing cutting depth and tool nose radius; both forces also increase with decreasing temperature. The resistance factor increases with increasing cutting depth and temperature, and decreases with increasing tool nose radius. [ABSTRACT FROM AUTHOR]

Red, green, and blue light InxGa1−xN multiple quantum wells have been grown on GaN/γ-LiAlO2 microdisk substrates by plasma-assisted molecular beam epitaxy. We established a mechanism to optimize the self-assembly growth with ball-stick model for InxGa1-xN multiple quantum well microdisks by bottom-up nanotechnology. We showed that three different red, green, and blue lighting micro-LEDs can be made of one single material (InxGa1-xN) solely by tuning the indium content. We also demonstrated that one can fabricate a beautiful InxGa1-xN-QW microdisk by choosing an appropriate buffer layer for optoelectronic applications. [ABSTRACT FROM AUTHOR]

The effects of temperature and size on the welding of Au nanowires (NWs) into T junctions is studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. Simulation results show that when the top NW approaches the bottom one, it elongates towards the bottom one just before welding due to the interaction of the van der Waals attractive force. During welding, the bottom NW gradually reaches critical bend deformation through successive pressure applied from the top one, followed by buckling of the top NW. The structural order of NWs significantly decreases with increasing welding temperature or decreasing NW width. Welding at high temperatures (700 K or above) causes alignment difficulty due to an unstable NW geometry or even welding failure due to a decrease in NW length. Smaller NWs have larger stress during the welding process. [ABSTRACT FROM PUBLISHER]

The goal of the current study is to clarify the relationship between social information processing (e.g., visual attention to cues of hostility, hostility attribution bias, and facial expression emotion labeling) and aggressive tendencies. Thirty adults were recruited in the eye-tracking study that measured various components in social information processing. Baseline aggressive tendencies were measured using the Buss-Perry Aggression Questionnaire (AQ). Visual attention towards hostile objects was measured as the proportion of eye gaze fixation duration on cues of hostility. Hostility attribution bias was measured with the rating results for emotions of characters in the images. The results show that the eye gaze duration on hostile characters was significantly inversely correlated with the AQ score and less eye contact with an angry face. The eye gaze duration on hostile object was not significantly associated with hostility attribution bias, although hostility attribution bias was significantly positively associated with the AQ score. Our findings suggest that eye gaze fixation time towards non-hostile cues may predict aggressive tendencies. [ABSTRACT FROM AUTHOR]

The mechanism of welding of Au–Au, Ag–Ag and Au–Ag nanowires (NWs) with head-to-head contact is studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. The effect of temperature in the range of 300–900 K is investigated. Simulation results show that at the initial welding, an incomplete jointing area forms through the interactions of the van der Waals attractive force, and that the jointing area increases with increasing the extent of contact between the two NWs during the welding process and temperature. Few defects form along the (1 1 1) close-packed plane during the welding process because the acting stress is quite low. Among the three NW pairs, the Au–Au NWs have the best cold-welding quality, whereas the Au–Ag NWs have the worst cold-welding quality due to the welding of different materials. With an increase in temperature, the weld stress and the mechanical strength of the NWs significantly decrease, and the number of disordered structures increases. The welding fails when the temperature exceeds the molten temperature of the NWs. [ABSTRACT FROM PUBLISHER]

The nanoscale milling and scratching processes of copper workpieces are studied using molecular dynamics simulations based on the tight-binding and Morse potentials. The effects of the rotation velocity of the tool and the workpiece temperature are evaluated in terms of atomic trajectories, slip vectors, flow field of chips, cutting forces and groove characteristics. The simulation shows that a slip system in the ⟨110⟩ direction on the workpiece surface occurs for milling with a tool rotation velocity of ω = 0°/fs. However, no apparent slip system appears for ω = 0.005°/fs or higher; instead, the number of amorphous areas increases. At ω = 0°/fs (nanoscratching), most of the removed atoms pile up in front of the tool and some gradually backfill when the tool rotates due to the effects of rotational friction and adhesion between the tool and the removed atoms. The largest number of removed atoms that piled up in front of the tool were obtained for milling with ω = 0°/fs; the number of removed atoms that piled up in front of the tool decreased with the increasing ω value. The component forces corresponding to the feed direction of the tool are the largest for the nanodrilling and nanomilling processes. High-precision grooves can be obtained at a low workpiece temperature (e.g. room temperature) with ω = 0°/fs. [ABSTRACT FROM PUBLISHER]

The effects of forming speed and temperature on the forming mechanism and mechanics of Cu 50 Zr 25 Ti 25 metallic glass are studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. These effects are investigated in terms of atomic trajectories, flow field, slip vectors, internal energy, radial distribution function, and elastic recovery of nanoimprint lithography (NIL) patterns. The simulation results show that a shear transformation zone (STZ) forms at the substrate surface underneath the mold during the forming process. The STZ area increases with mold displacement ( D ). The movement speed of substrate atoms underneath the mold increases with increasing D value. The movement directions of substrate atoms underneath the mold are more agreeable for a larger D value. The stick-slip phenomenon becomes more obvious with increasing D value and imprint speed. The substrate energy increases with increasing imprint speed and temperature. Great NIL pattern transfer is obtained with unloading at low temperatures (e.g., room temperature). [ABSTRACT FROM AUTHOR]

In order to improve the interface properties of bamboo in laminated board applications for severe outdoor environment, bamboo sheets were heat treated in soybean oil and post oil extracted in this paper. Following oil heat treatment at 180 °C for 2 h, bamboo specimens were either removed from the oil immediately or left in the oil until they were cooled to room temperature. Contact angle measurements before and after oil heat treatment showed a significant increase in the hydrophobicity of bamboo, and these changes differed based on the process parameters. Results from scanning electron microscopy and Fourier transform infrared spectroscopy indicated that these phenomena may be due to the combination effect of the change of chemical composition and the surplus oil on the surface of modified bamboo. Then, the ethanol extraction process was subsequently applied to remove the surplus oil. Finally, the results of bonding strength tests on laminated bamboo boards prepared from oil heat-treated samples which thereafter had been subjected to ethanol extraction showed acceptable interface properties, although lower than the reference. [ABSTRACT FROM AUTHOR]

Long-term endurance exercise could increase activity of parasympathetic nervous and decrease activity of sympathetic nervous at rest. However, previous studies all focused on the effect of endurance training on heart rate variability (HRV) for athletes or sedentary subjects. In Taiwan, elementary school teachers teaching and processing the children’s and administrative problems always stand and walk. They will sit down only when they review and correct the students’ home work. Thus, the goal of this study was to elucidate the beneficial effect of moderate intensity exercise on relieving mental load of elementary school teachers. There were 20 participants in the exercise group and another 20 participants in the nonexercise group. The exercising teachers performed 12 weeks of moderate intensity exercise training for an average of 30 minutes per day, 3 times per week. HRV was measured before and after the 4th, 6th, and 12th weeks. The time and frequency domain parameters of HRV all had significant increases between the beginning and after 12 weeks of training. However, the time and frequency domain parameters of HRV in the nonexercise group had significant decreases between the beginning and after 12 weeks of training. The long-term moderate exercises can relieve mental load of elementary school teachers. Moreover, age was the considerable factor affecting HRV in this study. [ABSTRACT FROM AUTHOR]

The nanodrilling process of copper substrates is studied using molecular dynamics simulations. The effects of the rotation velocity of the tool and substrate temperature are evaluated in terms of atomic trajectories, slip vector, thrust force, stress, flow field, and hole characteristics. The simulation shows that the main hole-making mechanism for drilling with low rotation velocities (0.1°/ps or lower) is mechanical indentation. The number of removed atoms and influence area of the substrate increase with increasing rotation velocity of the tool. When the rotation velocity of the tool or substrate temperature increases, the influence area expands more in the radial direction than in the axial direction. The required thrust force for making a hole is lower at a higher rotation velocity of the tool and higher substrate temperature. Undesirable elastic recovery after drilling can be reduced by increasing the rotation velocity of the tool. [ABSTRACT FROM AUTHOR]

Postoperative nausea (PON) is a common complication, and therefore, it is important to identify the associated genetic factors and the candidate predictive markers. Current clinical and basic research suggests that the 5-hydroxytryptamine type 3A receptor (HTR3A) may be important in the occurrence of PON. The association between three single nucleotide polymorphisms (SNPs) of the HTR3A gene and PON was examined to determine whether this can be used to predict the incidence of PON in a unique Taiwanese population without any reported postoperative nausea and vomiting (PONV) risk factors associated with PON occurrence. One thousand adult surgical patients who received general anesthesia were included in this analysis. A total of 369 patients were finally selected for a two-stage association study. Significant single-locus associations for all three HTR3A SNPs and PON were identified in both stages. In addition, two of the most common haplotypes, CTT and TAG, showed both a significant risk for and a protective effect against PON, respectively. Our findings support the notion that different haplotypes of HTR3A have reciprocal effects in the etiology of PON. Therefore specific haplotypes of HTR3A may be useful as predictors of PON for 24 h immediately after surgery in our population. [ABSTRACT FROM AUTHOR]