Search

Fluorine-based aluminum thermite have excellent ignition and combustion properties. Nonetheless, its combustion kinetics and energy release are hindered by slow mass diffusion and incomplete reactions. Therefore, this study successfully prepared an Al@PTFE composite with a core-shell structure, utilizing mechanical activation and sintering techniques, to enhance combustion properties and energy release rate. SEM, XRD, FTIR and XPS characterization results demonstrate the unique core-shell structure of the samples and the homogeneous distribution of elements on the surface. In comparison to the physical mixture, the Al@PTFE composite exhibits significantly higher values for P max (2.19 times), P max /Δt (11.30 times), and flame propagation velocity (4.5 times). Furthermore, the combustion duration required to reach the maximum flame height was reduced by 131.75 ms. The adsorption, decomposition and reaction processes of PTFE on the surface of aluminum particles were demonstrated based on RMD simulations. The promotion mechanism of PTFE on combustion in aluminum particles was elucidated. • Al@PTFE composite particles were successfully prepared by mechanical and thermal activation. • The ignition and combustion properties of Al@PTFE composite particles are much better than Al/PTFE composite particles. • The adsorption, dissociation and reaction processes of PTFE on the surface of alumina were observed at the molecular level. • PTFE destroys the alumina shell, creating a reaction site that induces an ignition reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] Aluminum nanoparticles are often considered attractive choices for fuels in energetic materials. In this study, molecular dynamics simulation with the reactive force field (ReaxFF) was used to study the oxidation process of three different particle sizes (4 nm, 5 nm, 6 nm) of ANPs (aluminum nano-particles). The cavity formation mechanism was obtained during the ANPs oxidation process. The cavity size, the oxide layer thickness, and the active aluminum content of ANPs with time were obtained. The results indicated that the formation of cavities is highly dependent on particle size. Large particle size prevents the formation of cavities. In 0–100 ps, the average growth rate of the oxide layer is 0.33, 0.25, and 0.20 nm/ps, respectively. Within 100–250 ps, the average growth rate of the oxide layer is −0.017, 0.038, and 0.117 nm/ps, respectively. Our results emphasize the effect of particle size on cavity formation, which provides insights into the atomic-scale oxidation mechanism of metal nanoparticles. [ABSTRACT FROM AUTHOR]

Despite the extensive researches on CL-20 crystals, the mechanical safety issues and process problems of CL-20 applications have not been studied in-depth. Herein, the cellulose nanocrystals (CNC) was doped in microcrystalline wax (MW), oxidized microcrystalline wax (OMW) and hydrogel (PPC) to design and fabricate the cross-linked CL-20 composites by simple water-suspension melting and freeze-drying methods. The composites were characterized by SEM, XPS, TG-DSC, XRD, mechanical sensitivity device and inclined chute tester. It is found that the CNC@OMW composite film exhibits excellent coating effect (99.96%) on CL-20 due to the cross-linking results. The E a of CL-20 is increased from 190.92 to 388.71 kJ/mol under the synergistic effect of the excellent compatibility between components and the compact coating structure of CNC@OMW. Additionally, the film enhances the T p0 of CL-20 from 218.15 to 222.66 ℃ and T b from 220.27 to 223.73 ℃, respectively. While, the PPC@CNC only promoted E a , T p0 and T b of CL-20–292.89.71 kJ/mol, 224.22 ℃ and 225.66 ℃, respectively. Besides, the XRD results confirms that three composite films dose not cause a transformation of the ε- CL-20 crystal phase. Most importantly, the cross-linked film brings mechanical sensitivity of CL-20 from 60 N and 3.5 J to a level of over 360 N and 10.4 J, comparable to WO 3 /Al nanothermite with 5 wt% polyaniline (360 N) and composite with 95 wt% LLM-105 and 5 wt% ternary (11–12 J). This improvement enables the composite explosives to be handled using standard procedures. Furthermore, the ability of the particles to accumulate electrostatic charge after cross-linking coating is significantly reduced, and PVC is more suitable as the contact material of CL-20 and composite particles than copper for use in the transportation and packaging. These findings can serve as a reference for wide application of CL-20. [Display omitted] • CNC was used as additive to enhance the desensitization and coating ability of composite film for CL-20. • The water suspension-melting method is a simple, scalable and cost-effective procedure for desensitization CL-20. • Hydrogel was used to coat CL-20, but its desensitization was limited. [ABSTRACT FROM AUTHOR]

Although the research on CL-20 crystals has reached a high level, the property of the explosive-desensitizer interface is a key concern for composite explosive applications. Herein, inspired by super adhesion performance on cup, the in-situ assembly ability of tea polyphenol (TP) was utilized to enhance the surface performance and desensitize CL-20. The five kinds of core-dual-shell composites were fabricated by the "one-pot" water suspension method under the influence of ionic charge, -OH bonding, and the structure like suction cup of ivy. They were characterized by SEM, XPS, TG-DSC, XRD, and mechanical sensitivity device. The morphology and surface analysis results indicated that TP and desensitizer were evenly coated on the surface of CL-20, forming a core-dual-shell structure. This provided a great structural contribution to its security. The thermal analysis results suggested that TP/microcrystalline wax (MW) was endowed with thermal decomposition activation energy (E a) of CL-20 from 190.92 kJ/mol up to 200.99 kJ/mol. While, the E a of CL-20/TP, CL-20/TP/GO, CL-20/TP/TPU, and CL-20/TP/TPU-PDA were only 189.33 kJ/mol, 190.61 kJ/mol, 199.77 kJ/mol, and 184.75 kJ/mol, respectively. Meanwhile, the TP/GO film reduced T p0 of CL-20 from 218.15 ℃ to 208.21 ℃ and T b from 220.27 ℃ to 210.14 ℃, respectively. Besides, the XRD results confirmed that the five films had not caused a transformation of the ε- CL-20 crystal phase, which afforded process safety support for the further application of these composite particles. Due to the properties of MW and the advantages of dual-shell composite structural, the TP/MW film brought mechanical sensitivity of CL-20 from 60 N and 3.5 J to 336 N and 8.97 J, closing to the level of PBXs with 95% LLM-105% and 5% ternary composite (11 J). These safety parameters indicate materiel of moderate sensitivity that possibly can be handled in accordance with standard procedures. Moreover, the particle coated with TP/TPU-PDA possessed better free-running property. These findings can provide reference for the large-scale application of CL-20. [Display omitted] • The TP was successfully coated on the surface of CL-20 by in-situ self-assembly. • The TP/GO composite film can reveal the thermal decomposition process of CL-20 in a segmented way. • The composite explosive was prepared by simple in-situ assembly and "one-plot" water suspension method. • Deep desensitization for CL-20 was achieved by using MW and dual-shell-core structure. [ABSTRACT FROM AUTHOR]

Abstract: Cadmium (Cd), through human activities, has severely accumulated in purple soil. Purple soil is considered as one of the most important types of agricultural soil in Southern China. In this study, we investigated the release of Cd from 13 purple soils with a wide range of total Cd content collected from vegetable fields and forestlands in Sichuan Basin. Soil batch extraction and column leaching experiments were conducted to determine the influence of chemical speciation, soil properties, soil water contact time, and soil/water ratio on the release characteristics of Cd from soil. Results indicate that Cd release was primarily present in exchangeable, carbonate-bound, and organically bound fractions. Moreover, precipitation-induced, long-term saturated conditions enhance the release of Cd from soil to water. Multiple regression analysis also shows that the release of Cd from soil is related to pH level, organic matter amount, and total Cd content in native soil. This finding explains the Cd release variation of 86% and 95% during batch extraction and column leaching experiments, respectively. Finally, this investigation provides a more convenient way of evaluating potential ecological risks of Cd in purple soil by determining the properties of several common soil types. [Copyright &y& Elsevier]

Abstract: The objective of the present paper is to incorporate the effect of plastic anisotropy on the fracture modeling of aluminum alloy 6061-T 6 sheets. Six different types of tests were performed to fracture, including tensile tests on classical dog-bone specimens, flat specimens with cutouts, plane strain grooved specimens, and punch indentation tests on circular blanks. A limited number of shear/tension tests on butterfly specimens were performed on a dual-actuator loading frame. Plastic properties were determined from the dog-bone tensile tests, and were verified by the remaining tests. It was found that the sheets exhibited little planar anisotropy but substantial out-of-plane anisotropy, characterized by the Lankford parameter, r. A comprehensive numerical analysis of the experiments revealed that the Hill 1948 quadratic anisotropic yield model is able to describe, with good accuracy, the plastic response of all five types of tests. Fracture surface strains were measured using a digital image correlation system. Average fracture strains were determined by measuring post-fracture thickness reduction. Local fracture strains were determined by means of an inverse engineering method involving matching the displacement to fracture from numerical simulations to those measured. Possible discrepancies between the magnitudes of the fracture strain in the three above methods are discussed. Based on the previous experience of the investigating team, the experimental fracture data were analyzed within the realm of the three-parameter Modified Mohr–Coulomb fracture model. Using the plane stress anisotropic plasticity equations, the calibrated fracture model was then transformed to the space of the equivalent strain to fracture and stress triaxiality. An alternative representation of the fracture locus in the space of principal strains was also constructed. Other important factors influencing the form of the fracture locus, such as mesh-size effect and solid versus shell representation, were also investigated. [Copyright &y& Elsevier]

Background: Although extrachromosomal DNA (ecDNA) has been intensively studied for several decades, the mechanisms underlying its tumorigenic effects have been revealed only recently. In most conventional sequencing studies, the high-throughput short-read sequencing largely ignores the epigenetic status of most ecDNA regions except for the junctional areas. Methods: Here, we developed a method of sequencing enzyme-accessible chromatin in circular DNA (CCDA-seq) based on the use of methylase to label open chromatin without fragmentation and exonuclease to enrich ecDNA sequencing depth, followed by long-read nanopore sequencing. Results: Using CCDA-seq, we observed significantly different patterns in nucleosome/regulator binding to ecDNA at a single-molecule resolution. Conclusions: These results deepen the understanding of ecDNA regulatory mechanisms. [ABSTRACT FROM AUTHOR]

Canine distemper virus (CDV) infection causes mass mortality in diverse carnivore species. For effective virus surveillance, rapid and sensitive assays are needed to detect CDV in field samples. In this study, after BABL/c mice were immunized with recombinant CDV-fusion (F) protein, monoclonal antibodies (mAbs) against recombinant CDV-F protein (designated 1A5, 1A6, and 7D5) were produced using traditional hybridoma cell technology. Next, capture antibody (1A6, 800 ng/well) and horseradish peroxidase (HRP)–conjugated detection antibody (HRP-7D5, 1:100, 500 ng/well) were used in a double monoclonal antibody–based sandwich enzyme-linked immunosorbent assay (ELISA) for CDV detection after optimization of both mAb amounts per well using a checkerboard titration test. Based on sandwich ELISA test results for 120 known CDV-negative samples, the cutoff value for a positive result was set to an OD450 nm value ≥ 0.196. As compared with test results obtained from commercial immune colloidal gold test strips, the low limits of detection for the two assays were revealed to be 100 TCID50 per 100 μL. In addition, the sandwich ELISA agreed 100% and 96.4% with commercial immune colloidal gold test strips when testing serum and stool samples. The sandwich ELISA assay provided statistically similar CDV detection. Thus, the sandwich ELISA developed here to detect CDV in fecal and serum samples provided good sensitivity, high specificity, and good reproducibility and should serve as an ideal method for large-scale surveillance of CDV infections in carnivores. Key points: • Three CDV mAbs that recognized different epitopes and bound to virion were generated. • The sandwich ELISA based mAbs to detect CDV in fecal and serum samples was developed. • The sandwich ELISA is an ideal method for detecting CDV infections in the field. [ABSTRACT FROM AUTHOR]

Developing therapeutics against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be guided by the distribution of epitopes, not only on the receptor binding domain (RBD) of the Spike (S) protein but also across the full Spike (S) protein. We isolated and characterized monoclonal antibodies (mAbs) from 10 convalescent COVID-19 patients. Three mAbs showed neutralizing activities against authentic SARS-CoV-2. One mAb, named 4A8, exhibits high neutralization potency against both authentic and pseudotyped SARS-CoV-2 but does not bind the RBD. We defined the epitope of 4A8 as the N-terminal domain (NTD) of the S protein by determining with cryo–eletron microscopy its structure in complex with the S protein to an overall resolution of 3.1 angstroms and local resolution of 3.3 angstroms for the 4A8-NTD interface. This points to the NTD as a promising target for therapeutic mAbs against COVID-19. [ABSTRACT FROM AUTHOR]

Evaporation‐induced self‐assembly of colloidal particles is one of the most versatile fabrication routes to obtain large‐area colloidal crystals; however, the formation of uncontrolled "drying cracks" due to gradual solvent evaporation represents a significant challenge of this process. While several methods are reported to minimize crack formation during evaporation‐induced colloidal assembly, here an approach is reported to take advantage of the crack formation as a patterning tool to fabricate microscopic photonic structures with controlled sizes and geometries. This is achieved through a mechanistic understanding of the fracture behavior of three different types of opal structures, namely, direct opals (colloidal crystals with no matrix material), compound opals (colloidal crystals with matrix material), and inverse opals (matrix material templated by a sacrificial colloidal crystal). This work explains why, while direct and inverse opals tend to fracture along the expected {111} planes, the compound opals exhibit a different cracking behavior along the nonclose‐packed {110} planes, which is facilitated by the formation of cleavage‐like fracture surfaces. The discovered principles are utilized to fabricate photonic microbricks by programming the crack initiation at specific locations and by guiding propagation along predefined orientations during the self‐assembly process, resulting in photonic microbricks with controlled sizes and geometries. [ABSTRACT FROM AUTHOR]

Long noncoding RNAs (lncRNA) expression profiles change in the ischemic brain after stroke, but their roles in specific cell types after stroke have not been studied. We tested the hypothesis that lncRNA modulates brain injury by altering macrophage functions. Using RNA deep sequencing, we identified 73 lncRNAs that were differentially expressed in monocyte-derived macrophages (MoDMs) and microglia-derived macrophages (MiDMs) isolated in the ischemic brain three days after stroke. Among these, the lncRNA, GM15628, is highly expressed in pro-inflammatory MoDMs but not in MiDMs, and are functionally related to its neighbor gene, lymphocyte cytosolic protein 1 (LCP1), which plays a role in maintaining cell shape and cell migration. We termed this lncRNA as Ma crophage c ontained L CP1 related p ro- i nflammatory l ncRNA, Maclpil. Using cultured macrophages polarized by LPS, M(LPS), we found that downregulation of Maclpil in M(LPS) decreased pro-inflammatory gene expression while promoting anti-inflammatory gene expression. Maclpil inhibition also reduced the migration and phagocytosis ability of MoDMs by inhibiting LCP1. Furthermore, adoptive transfer of Maclpil silenced M(LPS), reduced ischemic brain infarction, improved behavioral performance and attenuated penetration of MoDMs in the ischemic hemisphere. We conclude that by blocking macrophage, Maclpil protects against acute ischemic stroke by inhibiting neuroinflammation. [ABSTRACT FROM AUTHOR]

In order to expand applications of the Lanzhou microbeam the resent improvements were introduced in its slits, lens system and target chamber. In this study a beam optics of the new system was calculated for the 12C+6 ion beam of 966 MeV. To compensate a negative influence of a sector magnet dispersion on the beam dynamics an excitation of the magnetic quadrupole between two bending dipoles was determined. By varying parameters of the final triplet of magnetic quadrupole lenses a set of the microbeam systems with a stigmatic focusing were obtained. The best two of them were selected applying an optimization for a beam collimation by object and divergence slits. Simulation of the beam dynamics after the collimation allowed to determine the slit sizes that provide the highest current in the 1 µm probe on the target for these microbeam systems. Additionally, to improve the beam parameters at the microbeam entrance and then match the system parameters with this beam, the approach of an automatic probe-forming system is proposed. It is aimed at providing the highest possible resolution of the microbeam for the different beam varieties from a cyclotron. [ABSTRACT FROM AUTHOR]

Summary: Chitin is a structural and functional component of the fungal cell wall and also serves as a pathogen‐associated molecular pattern (PAMP) that triggers the innate immune responses of host plants. However, no or very little chitin is found in the fungus‐like oomycetes. In Phytophthora spp., the presence of chitin has not been demonstrated so far, although putative chitin synthase (CHS) genes, which encode the enzymes that synthesize chitin, are present in their genomes. Here, we revealed that chitin is present in the zoospores and released sporangia of Phytophthora, and this is most consistent with the transcriptional pattern of PcCHS in Phytophthora capsici and PsCHS1 in Phytophthora sojae. Disruption of the CHS genes indicated that PcCHS and PsCHS1, but not PsCHS2 (which exhibited very weak transcription), have similar functions involved in mycelial growth, sporangial production, zoospore release and the pathogenesis of P. capsici and P. sojae. We also suggest that chitin in the zoospores of P. capsici can act as a PAMP that is recognized by the chitin receptors AtLYK5 or AtCERK1 of Arabidopsis. These results provide new insights into the biological significance of chitin and CHSs in Phytophthora and help with the identification of potential targets for disease control. [ABSTRACT FROM AUTHOR]

Abstract Under compression, auxetic open cell cellular solids may lose auxeticity due to instability and/or self-contact between the ribs. This study explores the limiting strains for preserving auxetic effects for auxetic open cell materials of two different cellular structures: re-entrant honeycomb and the 'missing-rib' type chiral cellular solids. Experiments of the 3D printed specimens, periodicity analysis, and ellipticity analysis showed that, under compressive loads, the auxetic effects and the limiting compressive strain for auxeticity are mutually exclusive. In other words, the limiting compressive strain has to be reduced if larger auxetic effect is desired, vice versa. It was found that compared with re-entrant honeycombs, due to chirality-induced rotation, the chiral cellular solids can preserve auxetic effects under much larger compressive strain (>−10–30%). [ABSTRACT FROM AUTHOR]

In this paper, the pore structure and fractal characteristics of coal under liquid nitrogen cold soaking are tested for different coal qualities of anthracite, bituminous coal and lignite, and the variation patterns of BET specific surface area, BJH total hole and adsorption pore specific surface area with liquid nitrogen cold soaking times are studied. Among these coal samples, it is found that the raw bituminous coal has the most internal micropore content and the largest adsorption space for gas, followed by anthracite, and lignite is the last. After one time liquid nitrogen cold soaking, the increase of adsorption and percolation pore contents of each coal sample in the order of: anthracite > lignite > bituminous coal; and with the increase of liquid nitrogen cold soaking times, the internal pore size and number of pores of the three coal samples gradually increases, but the specific surface area of adsorption pores decreases. The reduction amplitude of the specific surface area of coal adsorption pores by one time liquid nitrogen cold soaking gradually increases with the increase of metamorphism. With the increase of liquid nitrogen cold soaking times, the average pore size, total BJH hole and percolation hole of each coal sample increases, while the BET specific surface area and adsorption pore specific surface area decreases gradually. The fractal dimension D 1 of each coal sample increases linearly with the increase of liquid nitrogen cold soaking times, and the variation of D 2 has an opposite trend. The results of this study can provide theoretical and experimental support for further application of liquid nitrogen to increase the permeability of coal seams. • Pore structure and fractal characteristics of coal under the liquid nitrogen cold soaking are tested. • Liquid nitrogen cold soaking could improve the coal pore connectivity. • Fractal dimension D 1 of coal increases linearly with the liquid nitrogen cold soaking number. [ABSTRACT FROM AUTHOR]

Oligodendrocyte precursor cells (OPCs) are needed for white matter repair after various brain injury. Means that promote OPC functions could benefit white matter recovery after injury. Chemokine CXCL12 and endothelial progenitor cells (EPCs) both have been shown to promote remyelination. We hypothesize that the beneficial effects of EPCs and CXCL12 can be harnessed by genetically modifying EPCs with cxcl12 to synergistically improve the functions of OPCs. In this work, CXCL12-EPC was generated using virus-mediated gene transfer. OPCs were cultured with CXCL12-EPC conditioned media (CM) to analyze its impact on the proliferation, migration, differentiation and survival properties of OPCs. We blocked or knocked-down the receptors of CXCL12, namely CXCR4 and CXCR7, respectively to investigate their functions in regulating OPCs properties. Results revealed that CXCL12-EPC CM further promoted OPCs behavioral properties and upregulated the expression of PDGFR-α, bFGF, CXCR4 and CXCR7 in OPCs, albeit following different time course. Blocking CXCR4 diminished the beneficial effects of CXCL12 on OPCs proliferation and migration, while knocking down CXCR7 inhibited OPCs differentiation. Our results supported that cxcl12 gene modification of EPCs further promoted EPCs’ ability in augmenting the remyelination properties of OPCs, suggesting that CXCL12-EPC hold great potential in white matter repair. [ABSTRACT FROM AUTHOR]

Surface patterns can be used as a selective coating platform on metal surfaces, in particular, under various deformation conditions because they induce local strain gradients along with pattern geometry. In this study, hard and flexible coating materials were introduced to regions with small and large deformations, respectively, on patterned magnesium (Mg) surfaces. Despite significant deformation, a polymer-ceramic coating on patterned Mg maintained its protection, as opposed to a ceramic coating on a flat Mg surface. Our proposed approach can be implemented in various Mg-based medical-device platforms by optimizing surface patterns on Mg depending on their loading conditions for clinical use. [ABSTRACT FROM AUTHOR]

To investigate the spatiotemporal dynamics of DNA damage and repair after the ion irradiation, an online live cell imaging system has been established based on the microbeam facility at Institute of Modern Physics (IMP). The system could provide a sterile and physiological environment by making use of heating plate and live cell imaging solution. The phototoxicity was investigated through the evaluation of DNA repair protein XRCC1 foci formed in HT1080-RFP cells during the imaging exposure. The intensity of the foci induced by phototoxicity was much lower compared with that of the foci induced by heavy ion hits. The results showed that although spontaneous foci were formed due to RFP exposure during live cell imaging, they had little impact on the analysis of the recruitment kinetics of XRCC1 in the foci induced by the ion irradiation. [ABSTRACT FROM AUTHOR]

The polyethylene terephthalate (PET) films were irradiated with single 6.9 MeV/u 58 Ni 19+ ions at the Lanzhou Interdisciplinary Heavy Ion Microbeam (LIHIM), and single conical nanopores were produced by asymmetric chemical etching of the latent ion tracks. Then, the current-voltage (I–V) characteristic was measured in LiCl, NaCl, KCl, MgCl 2 , and CaCl 2 solution at different concentrations to study the transport properties of different cations in the single conical nanopores respectively. The measured I–V data showed that the conical nanopores have rectified transportation of these cations at the applied voltage of between +2 V and −2 V. The rectification coefficient γ of the mono- and bivalent ions was determined in their solution of 0.0001–1 M measured at 1 V, the result showed that the rectification coefficient is dependent on the valence of the ions and the electrolyte solution. [ABSTRACT FROM AUTHOR]

Single-event-effects (SEEs) in integrated circuits (ICs) caused by galactic single ions are the major cause of anomalies for a spacecraft. The main strategies to decrease radiation failures for spacecraft are using SEEs less-sensitive devices and design radiation hardened ICs. High energy ion microbeam is one of the powerful tools to obtain spatial information of SEEs in ICs and to guide the radiation hardening design. The microbeam facility in the Institute of Modern Physics (IMP), Chinese Academy of Science (CAS) can meet both the liner energy transfer (LET) and ion range requirements for SEEs simulation experiments on ground. In order to study SEEs characteristics of ICs at this microbeam platform, a SEEs analysis system was developed. This system can target and irradiate ICs with single ions in micrometer-scale accuracy, meanwhile it acquires multi-channel SEE signals and maps the SEE sensitive regions online. A 4-Mbit NOR Flash memory was tested with this system using 2.2 GeV Kr ions, the radiation sensitive peripheral circuit regions for SEEs of 1 to 0 and 0 to 1 upset, multi-bit-upset and single event latchup have been obtained. [ABSTRACT FROM AUTHOR]

Irregular interdigitated morphology is prevalent in biological sutures in nature. Suture complexity index has long been recognized as the most important morphological parameter to govern the mechanical properties of biological sutures. However, the suture complexity index alone does not reflect all aspects of suture morphology. The goal of this investigation was to determine that besides suture complexity index, whether the degree of morphological irregularity of biological sutures has influences on the mechanical properties, and if there is any, how to quantify these influences. To explore these issues, theoretical and finite element (FE) suture models with the same suture complexity index but different levels of morphological irregularity were developed. The quasi-static stiffness, strength for damage initiation and post-failure process of irregular sutures were studied. It was shown that for the same suture complexity index, when the level of morphological irregularity increases, the overall strain to failure will increase while tensile stiffness is retained; also, the total energy to fracture increases with a sacrifice in strength to damage initiation. These results reveal that morphological irregularity is another important independent parameter to govern and balance the mechanical properties of biological sutures. Therefore, from the mechanics point of view, the prevalence of irregular suture morphology in nature is a merit, not a defect. [ABSTRACT FROM AUTHOR]

Background: Macrophages are involved in demyelination in many brain diseases. However, the role of macrophages in the recovery phase of the ischemic brain is unknown. The present study aims to explore the role of macrophages in the ischemic brain injury and tissue repair following a 90-min transient middle cerebral artery occlusion in mice.Methods: Clodronate liposomes were injected into mice to deplete periphery macrophages. These mice subsequently underwent middle cerebral artery occlusion. F4/80(+) and CD68(+) cells were examined in the mouse spleen and brain to confirm macrophage depletion at 14 days after middle cerebral artery occlusion. Modified neurological severity scores were used to evaluate the behavioral function between 1 and 14 days after middle cerebral artery occlusion. MBP, Iba1, and CD31 immunostaining were performed to determine myelin lesion, microglia activation, and microvessel density.Results: Clodronate liposomes depleted 80 % of the macrophages in the mouse spleen and reduced macrophage infiltration in the mouse brain. Macrophage depletion reduced the myelin damage in the ipsilateral striatum and microglia activation in both the ipsilateral cortex and striatum, enhanced the microvessel density in the peri-infarct region, attenuated brain atrophy, and promoted neurological recovery following middle cerebral artery occlusion.Conclusions: Our results suggested that macrophage depletion is a potential intervention that can promote tissue repair and remodeling after brain ischemia, reduce demyelination and microglia activation, and enhance focal microvessel density. [ABSTRACT FROM AUTHOR]

Aiming to assist stroke patients who suffer from motor dysfunction after stroke and reduce the stress of physiotherapists, a 3-degree-of-freedom (3DOF) lower limb rehabilitation robot (LLRR) has been developed for the motion recovery in this paper. At first, a simple and flexible structure of LLRR is designed, which involves hip, knee and ankle joints and can also be adjusted to fit for the different heights of patients. Then, for the controller design, control-oriented model of LLRR is studied and validated by both simulation and experiments, including the kinematic model of mechanical system, friction model of rotation joints and motor model of actuators. Based on the proposed models, an adaptive robust sub-controller is synthesized to make each joint track its designed training trajectory, overcome system uncertainties and reject the disturbances from patient. At last, experiments are carried out to validate the proposed LLRR by the passive movement training. [ABSTRACT FROM AUTHOR]

N -Alkoxyamides are successfully converted into their corresponding esters in a moderate to satisfactory yields via copper-catalyzed oxidative homocoupling and Heron rearrangement. The process tolerates a wide variety of functional groups and allows the synthesis of sterically hindered ester products not readily accessible by traditional acylation chemistry. A radical-mediated pathway has been tentatively proposed for the oxidative process. [ABSTRACT FROM AUTHOR]

Drilling noise has a bad impact on health and life of staff. Through field testing and analyzing drilling equipment noise in 21 drilling well site in Shengli Oilfield, it is found that noise source in the well site distributes scatteredly. The value of drilling noise constantly ranges from 73.2 dB to 109.4 dB, the largest noise of engine room can achieve 109.4 dB, the maximum noise value of drilling pumping room is 97.3 dB, and the noise at drilling floor can reach 93.4 dB. The rig with 3 200 m drilling depth can produce the highest noise, which exceeds 90 dB, and the noise will decrease with the increase of depth, then tend to stabilize at last. For the purpose of reducing noise, well site layout can be arranged reasonably, electrical power drilling technique and install insulation board around the main equipment and well site can be taken use of preferably. [ABSTRACT FROM AUTHOR]

Background: Metformin, a widely used hypoglycemic drug, reduces stroke incidence and alleviates chronic inflammation in clinical trials. However, the effect of metformin in ischemic stroke is unclear. Here, we investigated the effect of metformin on ischemic stroke in mice and further explored the possible underlying mechanisms.Methods: Ninety-eight adult male CD-1 mice underwent 90-minute transient middle cerebral artery occlusion (tMCAO). Metformin (200 mg/kg) was administrated for up to 14 days. Neurobehavioral outcomes, brain infarct volume, inflammatory factors, blood-brain barrier (BBB) permeability and AMPK signaling pathways were evaluated following tMCAO. Oxygen glucose deprivation was performed on bEND.3 cells to explore the mechanisms of metformin in inhibiting inflammatory signaling pathways.Results: Infarct volume was reduced in metformin-treated mice compared to the control group following tMCAO (P < 0.05). Neurobehavioral outcomes were greatly improved in metformin-treated mice (P < 0.05). MPO+ cells, Gr1+ cells, MPO activity and BBB permeability were decreased after metformin administration (P < 0.05). In addition, metformin activated AMPK phosphorylation, inhibited NF-κB activation, down-regulated cytokine (IL-1β, IL-6, TNF-α) and ICAM-1 expression following tMCAO (P < 0.05). Furthermore, metformin activated AMPK signaling pathway and alleviated oxygen-glucose deprivation-induced ICAM-1 expression in bEND.3 cells (P < 0.05). Compound C, a selective AMPK inhibitor, eliminated this promotional effect.Conclusions: Metformin down-regulated ICAM-1 in an AMPK-dependent manner, which could effectively prevent ischemia-induced brain injury by alleviating neutrophil infiltration, suggesting that metformin is a promising therapeutic agent in stroke therapy. [ABSTRACT FROM AUTHOR]

Three types of specifically pre-fabricated steel beam-column connections used in a special industrial steel structure were fabricated in full-scale, including the bolted end-plate connection with a short cantilever beam in the strong-axis of column (specimen I), the spatial weak-axis connection with a beam welded in the strong-axis of column (specimen II) and the planar cruciform weak-axis connection (specimen III), and then quasi-statically tested under cyclic loading to study their seismic performance and investigate the influence of bolted end-plate connection, spatial loading protocol and specific configuration details on the failure mode, ultimate capacity, plastic rotation, ductility and energy dissipation. The test results show that the plastic rotation of all the specimens exceeds 0.025 rad, and accumulated plastic rotation is 20 to 30 times larger than the maximum plastic rotation with a ductility coefficient greater than 4. 0. The measured flexural resistance of the specimens determined at the column face reaches 100% to 130% of the full plastic moment resistance of the connected beam, and the maximum story drift angle reaches 0. 035 rad for specimen II which finally fail by local buckling in the beam, and reaches 0. 040 rad for specimen I and III which fail by tensile failure of the bolt and ductile fracture in the cover plates respectively, and both satisfy the requirements for special moment frames in AISC Seismic Provisions. Specimen II and III are effective to guarantee the adequate capacity of consuming energy and ductility under seismic force, while the seismic performance of specimen I is relatively poor due to inadequate loading capacity of the bolted end-plate connection and should be improved in the view of design. [ABSTRACT FROM AUTHOR]

Abstract: Intravenous transplantation of endothelial progenitor cells (EPCs) reduced ischemic brain injury. However, less cell homing to damaged sites limited its functions. In present study, we labeled EPCs with silica-coated superparamagnetic iron oxide nanoparticles (SiO4@SPIONs) and applied exterior magnetic field to guide SiO4@SPIONs-labeled EPCs (SiO4@SPIONs-EPCs) to the ischemic hemisphere of the brain. We optimized SiO4@SPIONs labeling dose, which did not affect proliferation, migration and tube formation of EPCs in vitro. SiO4@SPIONs-EPCs homing was greatly increased in ischemic hemisphere with magnetic field treatment in mice underwent transient middle cerebral artery occlusion (tMCAO). Injection of SiO4@SPIONs-EPCs and followed by magnetic field treatment showed improved neurobehavioral outcomes, reduced brain atrophic volume, increased microvessel density and VEGF expression in the ischemic perifocal region compared to groups without magnetic field treatment (p < 0.05). Our results demonstrated that exterior magnetic field could guide SiO4@SPIONs-EPCs to ischemic region and enhance therapeutic effect, suggesting that magnetic-guided SiO4@SPIONs-EPCs delivery is a promising approach in cerebral ischemic therapy. [Copyright &y& Elsevier]

The simple and functional modification of the nanoparticle's surface is used to efficiently deliver chemotherapeutic drugs for anti-cancer treatment. Here, we construct a nanocrystalline drug delivery system with doxorubicin wrapped in red blood cell membranes for the treatment of mouse breast cancer models. Compared with traditional free drug treatments, the biodegradable natural red blood cell membrane is combined with pure crystalline drugs. The nanoparticles obtained by the preparation method have superior properties, such as good stability, significantly delaying the release of drugs and enhancing the inhibitory effect on tumor cells. This study shows that the design of RBC as an outsourced drug delivery system provides a promising foundation for the continued development, clinical trials, and nanomedicine research of anti-cancer drug nanocarriers in the future. [ABSTRACT FROM AUTHOR]

The article presents the discussion on two membrane proteins, Scap and Insig together monitoring the sterol level in the endoplasmic reticulum (ER) membrane including cholesterol homeostasis being controlled by the sterol regulatory element–binding protein (SREBP) pathway.

• Nanoscopic evidence for nuclear chromatin relaxation and remodeling upon ionizing radiation. • DNA damage response and repair were chromatin structure-dependent and also partly dependent on the distance to the DSB site. • Repair factors concentrated with nanoscale interlaced substructure in the DSB repair complex. • Nanoscale insight into the interplay between chromatin remodeling and DNA repair. The dynamic structure of nuclear chromatin and its regulation in the formation of repair complex is essential in DNA damage response and repair. Using single molecule localization microscopy STORM this work discovered that the nuclear chromatin organization was relaxed from 200 to 400 nm thick irregular frame and remodeled to dispersed sub-100 nm structure in HeLa cells after X-ray irradiation. The DSB repair factors (γ-H2AX, MDC1, 53BP1) showed distribution as microscale-colocalized and nanoscale interlaced substructure in the DSB repair complex. The dual-color nanoscopic imaging of γ-H2AX and chromatin at the DSB sites suggest that DNA damage response and repair cascade are chromatin structure-dependent and also partly dependent on the distance to the DSB sites. The sub-100 nm structure of fibers and nanoclusters of the relaxed nuclear chromatin and the DSB repair factors highly resembled the cross-section view of chromatin organization. These data demonstrated the polymorphic and dynamic behavior of the chromatin organization in vivo, and provided nanoscale insight into the interplay between chromatin remodeling and DNA damage response and DNA repair. [ABSTRACT FROM AUTHOR]

In order to solve the problem of pedestrian positioning in the indoor environment, this paper proposes a high-precision indoor pedestrian positioning system (HPIPS) based on smart phones. First of all, in view of the non-line-of-sight and multipath problems faced by the radio-signal-based indoor positioning technology, a method of using deep convolutional neural networks to learn the nonlinear mapping relationship between indoor spatial position and Wi-Fi RTT (round-trip time) ranging information is proposed. When constructing the training dataset, a fingerprint grayscale image construction method combined with specific AP (Access Point) positions was designed, and the representative physical space features were extracted by multi-layer convolution for pedestrian position prediction. The proposed positioning model has higher positioning accuracy than traditional fingerprint-matching positioning algorithms. Then, aiming at the problem of large fluctuations and poor continuity of fingerprint positioning results, a particle filter algorithm with an adaptive update of state parameters is proposed. The algorithm effectively integrates microelectromechanical systems (MEMS) sensor information in the smart phone and the structured spatial environment information, improves the freedom and positioning accuracy of pedestrian positioning, and achieves sub-meter-level stable absolute pedestrian positioning. Finally, in a test environment of about 800 m2, through a large number of experiments, compared with the millimeter-level precision optical dynamic calibration system, 94.2% of the positioning error is better than 1 m, and the average positioning error is 0.41 m. The results show that the system can provide high-precision and high-reliability location services and has great application and promotion value. [ABSTRACT FROM AUTHOR]

Photonic Microbricks: Fabrication of Photonic Microbricks via Crack Engineering of Colloidal Crystals (Adv. Funct. Keywords: colloidal crystals; fracture; nano/microfabrication; self-assembly EN colloidal crystals fracture nano/microfabrication self-assembly 1 1 1 06/27/20 20200625 NES 200625 In article number 1908242, Ling Li and co-workers provide a mechanistic understanding of crack formations during the evaporation-induced self-assembly of colloidal crystals, which allows for rational controlling of the location and orientation of cracks for fabricating photonic microstructures with controlled geometries and sizes. Colloidal crystals, fracture, nano/microfabrication, self-assembly. [Extracted from the article]

In view of the inability of Global Navigation Satellite System (GNSS) to provide accurate indoor positioning services and the growing demand for location-based services, indoor positioning has become one of the most attractive research areas. Moreover, with the improvement of the smartphone hardware level, the rapid development of deep learning applications on mobile terminals has been promoted. Therefore, this paper borrows relevant ideas to transform indoor positioning problems into problems that can be solved by artificial intelligence algorithms. First, this article reviews the current mainstream pedestrian dead reckoning (PDR) optimization and improvement methods, and based on this, uses the micro-electromechanical systems (MEMS) sensor on a smartphone to achieve better step detection, stride length estimation, and heading estimation modules. In the real environment, an indoor continuous positioning system based on a smartphone is implemented. Then, in order to solve the problem that the PDR algorithm has accumulated errors for a long time, a calibration method is proposed without the need to deploy any additional equipment. An indoor turning point feature detection model based on deep neural network is designed, and the accuracy of turning point detection is 98%. Then, the particle filter algorithm is used to fuse the detected turning point and the PDR positioning result, thereby realizing lightweight cumulative error calibration. In two different experimental environments, the performance of the proposed algorithm and the commonly used localization algorithm are compared through a large number of experiments. In a small-scale indoor office environment, the average positioning accuracy of the algorithm is 0.14 m, and the error less than 1 m is 100%. In a large-scale conference hall environment, the average positioning accuracy of the algorithm is 1.29 m, and 65% of the positioning errors are less than 1.50 m which verifies the effectiveness of the proposed algorithm. The simple and lightweight indoor positioning design scheme proposed in this article is not only easy to popularize, but also provides new ideas for subsequent scientific research in the field of indoor positioning. [ABSTRACT FROM AUTHOR]

High-precision navigation and positioning technology for indoor areas has become one of the research hotspots in the current navigation field. However, due to the complexity of the indoor environment, this technology direction is also one of the research difficulties. At present, our common indoor positioning methods are WIFI, Bluetooth, LED, ultrasound and pseudo satellite. However, due to the problem of inaccurate direct or indirect ranging, the positioning accuracy is usually affected, which makes the final application difficult to achieve. In order to avoid the ranging limitations of the existing methods, a new dual-frequency entanglement constraint (DFEC) ranging method based on homologous base station is proposed in this paper. The relationship between the homologous characteristics of dual-frequency signals and the phase relationship within the cycle is used to estimate the current carrier phase adjustment the true value of the cycle count is used to get rid of the constraints of the ranging conditions and improve the ranging accuracy. In order to verify the feasibility of this method, the wired environment test and the typical characteristic points of wireless environment are tested and analyzed respectively. The analysis results show that in the wired environment, the transmitting base station and the receiving terminal will introduce a ranging error of one wavelength; in the wireless environment, due to the influence of spatial noise and multipath, the error of the estimation of the whole cycles of the ranging value increases significantly. And this phenomenon is most obvious especially in the region where the signal is shaded, but the error estimate that satisfies ± 1 wavelength still accounts for 90%. Based on this, we conduct multiple observation data collection at five typical feature points, and used existing MATLAB positioning algorithms to conduct positioning error tests. The analysis found that under this error condition, the positioning accuracy was about 0.6 m, and 93% of the points met the 1-m positioning accuracy. [ABSTRACT FROM AUTHOR]

• A combined system of vacuum membrane distillation and mechanical vapor recompression was proposed. • Water production performance and thermal efficiency were experimentally investigated. • The energy recovery characteristics were analyzed comprehensively. This paper presents a study of the combined system of vacuum membrane distillation (VMD) and mechanical vapor recompression (MVR) for the treatment of sulfuric acid solution. A lab-scale VMD setup with polytetrafluoroethylene (PTFE) microporous membranes using sulfuric acid solution as feed was used to investigate the effects of operating parameters on water production performance. The thermal efficiency in VMD process was then analyzed. Finally, further investigation about the energy recovery characteristic of the proposed system were carried out by analyzing the variation laws of the vapor saturated temperature rise of the compressor. The results showed that sulfuric acid solution could be concentrated up to 50 % by the VMD technology, and the separation efficiency was 99.9 %. However, the energy requirement was still larger due to lower thermal efficiency caused by the heat loss to the environment and the absence of recovery of latent heat of vaporization. The MVR process could achieve the enhancement of energy efficiency in the VMD process by recovering the latent heat of vaporization, the optimum permeate-side absolute pressure under different feed concentrations was obtained, which could ensure the minimum energy consumption, the energy saving of 65.5 % was observed in comparison with the conventional VMD system. [ABSTRACT FROM AUTHOR]

Instability-induced pattern transformations of the architectured multi-phase soft metamaterial under bi-axial compression were explored. The soft metamaterial is composed of two phases: a soft matrix and a reinforcing hexagonal network embedded in the matrix. Equi-biaxial loading is found to induce both micro- and macro- instabilities in the networked architecture. Two types of instability patterns were observed, dependent upon the architecture geometry and the material combination. The critical strain for triggering instability and the two resulting types of patterns was derived, and a theoretical criterion for the transition between the two patterns was determined. Type I patterns retain the original periodicity of the architecture but wrinkles the network walls whereas Type II patterns transform the overall periodicity of the architecture while bending the network walls. Elastic wave propagation analysis was performed for the two distinct patterns under both stressed and stress-free conditions: a change in band gaps is found for both instability-induced pattern transformations, but differs for each type due to their dramatic difference in structure transformation (i.e. Type I wall wrinkling vs. Type II periodicity switching). The distinguished mechanical behavior and the rich properties of this category of multi-phase soft metamaterial can be used to design new smart materials with switchable functionalities controllable by deformation. [ABSTRACT FROM AUTHOR]

An abstract of the article "Copper-Mediated Oxidative Homocoupling and Rearrangement of N-Alkoxyamides: An Efficient Method for the Preparation of Aromatic Esters" by X. Duan and colleagues is presented.