MWCNT Doped Reverse-Mode Polymer Network Liquid Crystals with Frequency Response Property

Polymer-liquid crystals(PLCs)are common materials for smart windows.However,PLC smart windows usually require high driving voltage to maintain transparency.We synthesized a novel PLC smart film by doping multi-wall carbon nanotubes(MWCNTs)into a reverse-mode polymer network liquid crystal(R-PNLC).

成年小鼠脊髓损伤后跑步机训练通过上调过氧化物酶体增殖物激活受体γ共激活剂1α促进髓鞘修复

越来越多的证据证明体育锻炼对脊髓损伤(SCI)后髓鞘再生和运动功能表现的有效性。然而,跑步机训练对SCI后髓鞘修复和功能恢复的分子机制尚未得到充分研究。本研究探讨了跑步机训练对小鼠胸T10挫伤模型中上调过氧化物酶体增殖物激活受体γ共激活剂1 α(PGC1α)介导的髓鞘修复和功能恢复的影响。对SCI的小鼠进行为期4周的跑步机训练计划。采用免疫荧光、RNA荧光原位杂交和Western blotting检测少突胶质细胞生成相关蛋白和PGC1α的表达水平。使用透射电子显微镜(TEM)观察髓鞘结构。Basso Mouse Scale(BMS)和CatWalk自动步态分析系统用于运动功能恢复评估,并检查了运动诱发电位(MEP)。此外,腺相关病毒(AAV)介导的少突胶质细胞(OLs)中PGC1α敲低被用来进一步揭示PGC1α在运动诱导的髓鞘再生中的作用。我们发现SCI之后跑步机训练可促进少突胶质细胞前体细胞(OPC)增殖,促进少突胶质细胞(OL)成熟,并增加髓鞘相关蛋白和髓鞘厚度,从而促进髓鞘修复和后肢功能表现以及神经传导的速度和幅度的改善。此外,通过AAV下调PGC1α减弱了跑步机训练的这些积极作用。总之,我们的结果表明跑步机训练通过上调PGC1α来增强髓鞘再生和功能恢复,这为理解体育锻炼对髓鞘修复的作用向前迈出了一步。

Time-sequential color code division multiplexing holographic display with metasurface

Color metasurface holograms are powerful and versatile platforms for modulating the amplitude,phase,polarization,and other properties of light at multiple operating wavelengths.However,the current color metasurface holography can only realize static manipulation.In this study,we propose and demonstrate a multiplexing metasurface technique combined with multiwavelength code-division multiplexing(CDM)to realize dynamic manipulation.Multicolor code references are utilized to record information within a single metasurface and increase the information capacity and security for anticracks.A total of 48 monochrome images consisting of pure color characters and multilevel color video frames were reconstructed in dual polarization channels of the birefringent metasurface to exhibit high information density,and a video was displayed via sequential illumination of the corresponding code patterns to verify the ability of dynamic manipulation.Our approach demonstrates significant application potential in optical data storage,optical encryption,multiwavelengthversatile diffractive optical elements,and stimulated emission depletion microscopy.

Synergistic effect of total ionizing dose on single-event gate rupture in SiC power MOSFETs

The synergistic effect of total ionizing dose(TID) and single event gate rupture(SEGR) in SiC power metal–oxide–semiconductor field effect transistors(MOSFETs) is investigated via simulation. The device is found to be more sensitive to SEGR with TID increasing, especially at higher temperature. The microscopic mechanism is revealed to be the increased trapped charges induced by TID and subsequent enhancement of electric field intensity inside the oxide layer.

A surfactant-modified composite separator for high safe lithium ion battery

Separators have been gaining increasing attention to improve the performance of lithium ion batteries(LIBs),especially for high safe and long cycle life.However,commercial polyolefin separators still face the problems of rapid capacity decay and safety issues due to the poor wettability with electrolytes and low thermal stability.Herein,a novel composite separator is proposed by introducing a surfactant of sodium dodecyl thiosulfate(SDS)into the polytetrafluoroethylene(PTFE)substrate with the binder of polyacrylic acid(PAA)through the suction filtration method.The introduction of PAA/SDS enhances the adsorption energy between PTFE substrate and electrolyte through density functional theory calculations,which improves wettability and electrolyte uptake of the separator significantly.The asachieved composite separator enables the LIBs to own high Li^(+)conductivity(0.64×10^(-3)S cm^(-1))and Li^(+)transference number(0.63),further leading to a high capacity retention of 93.50%after 500 cycles at 1 C.In addition,the uniform and smooth surface morphology of Li metal employed the composite separator after cycling indicates that the lithium dendrites can be successfully inhibited.This work indicates a promising route for the preparation of a novel composite separator for high safe LIBs.

A reconfigurable dynamic Bayesian network for digital twin modeling of structures with multiple damage modes

Dynamic Bayesian networks(DBNs)are commonly employed for structural digital twin modeling.At present,most researches only consider single damage mode tracking.It is not sufficient for a reusable spacecraft as various damage modes may occur during its service life.A reconfigurable DBN method is proposed in this paper.The structure of the DBN can be updated dynamically to describe the interactions between different damages.Two common damages(fatigue and bolt loosening)for a spacecraft structure are considered in a numerical example.The results show that the reconfigurable DBN can accurately predict the acceleration phenomenon of crack growth caused by bolt loosening while the DBN with time-invariant structure cannot,even with enough updates.The definition of interaction coefficients makes the reconfigurable DBN easy to track multiple damages and be extended to more complex problems.The method also has a good physical interpretability as the reconfiguration of DBN corresponds to a specific mechanism.Satisfactory predictions do not require precise knowledge of reconfiguration conditions,making the method more practical.

Surface reconstruction of Se-doped NiS_(2) enables high-efficiency oxygen evolution reaction

Surface reconstruction of electrocatalysts has been widely witnessed during the electrochemical processes.Here,NiS_(2),NiSe_(2), and Se doped NiS_(2)(Se-NiS_(2)) are fabricated for oxygen evolution reaction(OER) through a mild sulfuration and/or selenylation process of Ni(OH)_(2) supported on carbon cloth(CC).Through careful in-situ Raman spectroscopy and ex-situ X-ray photoelectron spectroscopy,surface reconstruction of NiS_(2),NiSe_(2),and Se-NiS_(2) during the OER process has been revealed.A potentialdependent study shows that Se-NiS_(2) undergoes surface evolution at lower potentials and requires the lowest potential for conversion to NiOOH as a highly OER-active species,accompanied by the leaching of SO_(4)^(2-) and SeO_(4)^(2-) that can again be adsorbed on the catalyst surface to enhance the catalytic activity.Density functional theory(DFT) calculations confirm that Se-NiS_(2) is more susceptible to surface oxidation through the OER process.Therefore,Se-NiS_(2) exhibits outstanding OER activity and stability in alkaline conditions,requiring an overpotential of 343 mV at a current density of 50 mA cm^(-2).A novel insight is provided by our work in understanding the surface reconstruction and electrocatalytic mechanism of Ni-based chalcogenides.

Observation of Enhanced Faraday Effect in Eu-Doped Ce:YIG Thin Films

Ce:YIG thin films are taken as an ideal candidate for magneto-optical devices with giant Faraday effect in the near-infrared range,but it is hindered by a limited Ce^(3+)/Ce^(4+)ratio and a high saturation driving field.To address this issue,Eu doping can increase the Faraday rotation angle by ~40% to 1.315×10^(4)deg/cm and decrease the saturation driving field by ~38%to 1.17 kOe in Eu_(0.75)Ce_(1)Y_(1.25)Fe_(5)O_(12 )compared to Ce_(1)Y_(2)Fe_(5)O_(12)pristine.The mechanism is attributed to the conversion of Ce^(4+)to Ce^(3+)and the weakening of ferrimagnetism by Eu doping.This work not only provides strategies for improving Ce^(3+)/Ce^(4+) ratio in Ce:YIG,but also develops(Eu,Ce):YIG with a promising Faraday rotation angle for magneto-optical devices.

Multiple inducible thermogenic mechanisms in the development of cold acclimatization

Extreme cold environment can threaten human health and life through increasing the risk of myocardial infarction,stroke,frostbite,and hypothermia.Insufficient heat production to maintain core body temperature is a major cause of cold injury.To cope with cold stress,human and other mammals have developed the capacity of cold acclimatization to adapt to such a harsh environment.Adaptive non-shivering thermogenesis is a ubiquitous form of cold acclimatization.This review article systematically summarizes the role of three inducible thermogenic forms,including food intake,circadian rhythms,and cold exposure in mediating non-shivering thermogenesis under cold exposure and presents the potential interventions for minimizing the adverse health consequences of cold temperature.

Normalized fatigue properties of asphalt mixture at various temperatures

This study normalized the mixture's fatigue behavior at various temperatures,and the strength and fatigue tests of the mixture were conducted.The stress state of the asphalt mixture includes direct tensile,uniaxial compression,and indirect tensile.The Desai yield surface and fatigue path were proposed.And a normalized fatigue characteristics model of the mixture was established.The following conclusions were obtained.With the increases in the loading rate,the strength of the asphalt mixture increased.As the temperature increases,the strength of the mixture is reduced.At various temperatures and rates,the strength forms a closed curved surface.The Desai strength yield surface was established,which forms a closed curved surface.When the loading rate and temperature are below a certain critical line,the asphalt mixture will not undergo strength damage.At a fixed stress state,the fatigue damage path of the mixture was determined.The stress ratio was determined considering the influence of the loading rate.In this way,a normalized model can be described to express the asphalt mixture fatigue properties at various temperatures and stress levels.For the asphalt mixture in an indirect tensile state,the normalized fatigue equation parameter is 4.09.This model is more suitable for reflecting the viscous-elastic behavior of the mixtures than the fatigue equation determined by the notional stress ratio.

Regulatory role of exosomes in colorectal cancer progression and potential as biomarkers

Colorectal cancer(CRC)remains an enormous challenge to human health worldwide.Unfortunately,the mechanism underlying CRC progression is not well understood.Mounting evidence has confirmed that exosomes play a vital role in CRC progression,which has attracted extensive attention among researchers.In addition to acting as messengers between CRC cells,exosomes also participate in the CRC immunomodulatory process and reshape immune function.As stable message carriers and liquid biopsy option under development,exosomes are promising biomarkers in the diagnosis or treatment of CRC.In this review we have described and analyzed the biogenesis and release of exosomes and current research on the role of exosomes in immune regulation and metastasis of CRC.Moreover,we have discussed candidate exosomal molecules as potential biomarkers to diagnose CRC,predict CRC progression,or determine CRC chemoresistance,and described the significance of exosomes in the immunotherapy of CRC.This review provides insight to further understand the role of exosomes in CRC progression and identify valuable biomarkers that facilitate the clinical management of CRC patients.

Total ionizing dose and synergistic effects of magnetoresistive random-access memory

A magnetoresistive random-access memory(MRAM) device was irradiated by ^(60) Co c-rays and an electron beam.The synergistic effect of this on the MRAM was tested with an additional magnetic field during irradiation,from which the total ionizing dose(TID) and the synergistic damage mechanism of MRAM were analyzed.In addition,DC,AC,and functional parameters of the memory were tested under irradiation and annealing via a very large-scale integrated circuit test system.The radiation-sensitive parameters were obtained through analyzing the data.Because of the magnetic field applied on the MRAM while testing the synergistic effects,shallow trench isolation leakage and Frenkel–Poole emission due to synergistic effects were smaller than that of TID,and hence radiation damage of the synergistic effects was also lower.

Radioprotective effects of cimetidine on rats irradiated by long-term, low-dose-rate neutrons and ^(60)Coγ-rays

Background: Cimetidine, an antagonist of histamine type II receptors, has shown protective effects against γ-rays or neutrons. However, there have been no reports on the effects of cimetidine against neutrons combined with γ-rays. This study was carried out to evaluate the protective effects of cimetidine on rats exposed to long-term, low-dose-rate neutron and γ-ray combined irradiation(n-γ LDR).Methods: Fifty male Sprague-Dawley(SD) rats were randomly divided into 5 groups: the normal control group, radiation model group, 20mg/(kg·d) cimetidine group, 80mg/(kg·d) cimetidine group and 160mg/(kg·d) cimetidine group(10 rats per group). Except for the normal control group, 40 rats were simultaneously exposed to fission neutrons(^(252)Cf, 0.085 m Gy/h) for 22 h every day and γ-rays(^(60)Co, 0.097Gy/h) for 1.03 h once every three days, and the cimetidine groups were administered intragastrically with cimetidine at doses of 20, 80 and 160mg/kg each day. Peripheral blood WBC of the rats was counted the day following exposure to γ-rays. The rats were anesthetized and sacrificed on the day following exposure to ^(252)Cf for 28 days. The spleen, thymus, testicle, liver and intestinal tract indexes were evaluated. The DNA content of bone marrow cells and concanavalin A(Con A)-induced lymphocyte proliferation were measured. The frequency of micronuclei in polychromatic erythrocytes(f MNPCEs), superoxide dismutase(SOD), malondialdehyde(MDA), and glutathione peroxidase(GSH-Px) in the serum and liver tissues were detected.Results: The peripheral blood WBC in the cimetidine groups was increased significantly on the 8th day and the 26 th day compared with those in the radiation model group. The spleen, thymus and testicle indexes of the cimetidine groups were higher than those of the radiation model group. The DNA content of bone marrow cells and lymphocyte proliferation in the cimetidine groups were increased significantly, and fMNPCE was reduced 1.41-1.77 fold in cimetidine treated groups. The activities of SOD and GSH-Px in the cimetidine groups were increased significantly, and the content of MDA in the cimetidine groups was decreased significantly.Conclusions: The results suggested that cimetidine alleviated damage induced by long-term, low-dose-rate neutron and γ combined irradiation via antioxidation and immunomodulation. Cimetidine might be useful as a potent radioprotector for radiotherapy patients as well as for occupational exposure workers.

Changes and spatial patterns of the differences between ground and air temperature over the Qinghai-Xizang Plateau

The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial distribution and time changing tendency have been diagnosed by principal component analysis and power spectral analysis methods. The results show that the values of （Ts-Ta） are the maximum in June and the minimum in December. The first three loading eigenvectors, which reflect the main spatially anomalous structure of （Ts-Ta） over the Qinghai-Xizang Plateau, contain the contrary changing pattern between the northwestern and the southeastern regions, the pattern response of the sea level elevation and the geography, and the pattern response of the distribution of the permafrost. There are four patterns of time evolution including the patterns of monotonous increasing or decreasing trends, the basic stability pattern and the parabola pattern with the minimum value. （Ts-Ta） has a periodic variation about 2 years. According to the spatial distribution of the third loading eigenvectors of （Ts-Ta） over the Qinghai-Xizang Plateau in cold season, the permafrost response region and the seasonal frozen ground response region are identified.

Experiment and evaluation of wrinkling strain in a corner tensioned square membrane

Prediction of wrinkling characteristics is strongly correlated with the strain perpendicular to wrinkling direc- tion. In this paper, the strain field of wrinkled membrane is tested by VIC-3D system based on the digital image correlation technique. Experimental results are validated by the tension wrinkling simulation. The experimental strain perpendicular to wrinkling direction is analyzed in depth. The wrinkling strain of a square wrinkled membrane under corner tension is extracted from experimental strain perpendicular to wrinkling direction. A quantitative characterization format of the experimental wrinkling strain is proposed. A modified prediction method of wrinkling amplitude is presented based on the experimental wrinkling strain. The re- sults show that the precision of modified prediction model has improved 13.2% compared with the classical prediction model. The results reveal that the modified model can give an accurate prediction of the wrinkling amplitude.

Total ionizing dose effects in pinned photodiode complementary metal-oxide-semiconductor transistor active pixel sensor

A pinned photodiode complementary metal–oxide–semiconductor transistor（CMOS） active pixel sensor is exposed to ^60Co to evaluate the performance for space applications. The sample is irradiated with a dose rate of 50 rad（SiO2）/s and a total dose of 100 krad（SiO2）, and the photodiode is kept unbiased. The degradation of dark current, full well capacity,and quantum efficiency induced by the total ionizing dose damage effect are investigated. It is found that the dark current increases mainly from the shallow trench isolation（STI） surrounding the pinned photodiode. Further results suggests that the decreasing of full well capacity due to the increase in the density, is induced by the total ionizing dose（TID） effect, of the trap interface, which also leads to the degradation of quantum efficiency at shorter wavelengths.

Synergistic effects of total ionizing dose and radiated electromagnetic interference on analog-to-digital converter

The influence of combined total ionization dose(TID)and radiated electromagnetic interference(EMI)in a commercial analog-to-digital converter(ADC)was studied.The degradation of the direct-current response,the static parameters,and the dynamic parameters caused by the TID and EMI separately and synergistically is presented.The experimental results demonstrate that the increase in TID intensifies data error and the signal-tonoise ratio(SNR)degradation caused by radiated EMI.The cumulative distribution function of EMI failure with respect to data error and SNR with different TIDs was extracted.The decreasing trend of the threshold was acquired with a small sample size of five for each TID group.The result indicates that the ADC is more sensitive in a compound radiation environment.

Ultrathin, Lightweight, and Flexible CNT Buckypaper Enhanced Using MXenes for Electromagnetic Interference Shielding

Lightweight,flexibility,and low thickness are urgent requirements for next-generation high-performance electromagnetic interference(EMI)shielding materials for catering to the demand for smart and wearable electronic devices.Although several efforts have focused on constructing porous and flexible conductive films or aerogels,few studies have achieved a balance in terms of density,thickness,flexibility,and EMI shielding effectiveness(SE).Herein,an ultrathin,lightweight,and flexible carbon nanotube(CNT)buckypaper enhanced using MXenes(Ti3C2Tx)for high-performance EMI shielding is synthesized through a facile electrophoretic deposition process.The obtained Ti3C2Tx@CNT hybrid buckypaper exhibits an outstanding EMI SE of 60.5 dB in the X-band at 100μm.The hybrid buckypaper with an MXene content of 49.4 wt%exhibits an EMI SE of 50.4 dB in the X-band with a thickness of only 15μm,which is 105%higher than that of pristine CNT buckypaper.Furthermore,an average specific SE value of 5.7×10^(4) dB cm^(2) g^(−1) is exhibited in the 5-μm hybrid buckypaper.Thus,this assembly process proves promising for the construction of ultrathin,flexible,and high-performance EMI shielding films for application in electronic devices and wireless communications.

Beneficial effects of a novel shark-skin collagen dressing for the promotion of seawater immersion wound healing

Background: Wounded personnel who work at sea often encounter a plethora of difficulties. The most important of these difficulties is seawater immersion. Common medical dressings have little effect when the affected area is immersed in seawater, and only rarely dressings have been reported for the treatment of seawater-immersed wounds. The objective of this study is to develop a new dressing which should be suitable to prevent the wound from seawater immersion and to promote the wound healing.Methods: Shark skin collagen(SSC) was purified via ethanol de-sugaring and de-pigmentation and adjusted for p H. A shark skin collagen sponge(SSCS) was prepared by freeze-drying. SSCS was attached to an anti-seawater immersion polyurethane(PU) film(SSCS+PU) to compose a new dressing. The biochemical properties of SSC and physicochemical properties of SSCS were assessed by standard methods. The effects of SSCS and SSCS+PU on the healing of seawaterimmersed wounds were studied using a seawater immersion rat model. For the detection of SSCS effects on seawaterimmersed wounds, 12 SD rats, with four wounds created in each rat, were divided into four groups: the 3 rd day group, 5 th day group, 7 th day group and 12 th day group. In each group, six wounds were treated with SSCS, three wounds treated with chitosan served as the positive control, and three wounds treated with gauze served as the negative control. For the detection of the SSCS+PU effects on seawater-immersed wounds, 36 SD rats were divided into three groups: the gauze(GZ)+PU group, chitosan(CS)+PU group and SSCS+PU group, with 12 rats in each group, and two wounds in each rat. The wound sizes were measured to calculate the healing rate, and histomorphology and the immunohistochemistry of the CD31 and TGF-β expression levels in the wounded tissues were measured by standard methods.Results: The results of Ultraviolet-visible(UV-vis) spectrum, Fourier-transform infrared(FTIR) spectrum, circular dichroism(CD) spectra, sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE), and amino acid composition analyses of SSC demonstrated that SSC is type I collagen. SSCS had a homogeneous porous structure of approximately 200μm, porosity rate of 83.57%±2.64%, water vapor transmission ratio(WVTR) of 4500 g/m2, tensile strength of 1.79±0.41 N/mm, and elongation at break of 4.52%±0.01%. SSCS had significant beneficial effects on seawater-immersed wound healing. On the 3 rd day, the healing rates in the GZ negative control, CS positive control and SSCS rats were 13.94%±5.50%, 29.40%±1.10% and 47.24%±8.40%, respectively. SSCS also enhanced TGF-in the initial stage of the healing period. The SSCS+PU dressing effectively protected woundsβ and CD31 expression from seawater immersion for at least 4 h, and accelerated re-epithelialization, vascularization and granulation formation of seawater-immersed wounds in the earlier stages of wound healing, and as well as significantly promoted wound healing. The SSCS+PU dressing also enhanced expression of TGF-n and gauze dressings.β and CD31. The effects of SSCS and SSCS+PU were superior to those of both the chitosaConclusion: SSCS has significant positive effects on the promotion of seawater-immersed wound healing, and a SSCS+PU dressing effectively prevents seawater immersion, and significantly promotes seawater-immersed wound healing.

Impact of switching frequencies on the TID response of SiC power MOSFETs

Different switching frequencies are required when SiC metal-oxide-semiconductor field-effect transistors(MOSFETs)are switching in a space environment.In this study,the total ionizing dose(TID)responses of SiC power MOSFETs are investigated under different switching frequencies from 1 kHz to 10 MHz.A significant shift was observed in the threshold voltage as the frequency increased,which resulted in premature failure of the drain-source breakdown voltage and drain-source leakage current.The degradation is attributed to the high activation and low recovery rates of traps at high frequencies.The results of this study suggest that a targeted TID irradiation test evaluation method can be developed according to the actual switching frequency of SiC power MOSFETs.