Multifunctional Integrated Organic-Inorganic-Metal Hybrid Aerogel for Excellent Thermal Insulation and Electromagnetic Shielding Performance

Vehicles operating in space need to withstand extreme thermal and electromagnetic environments in light of the burgeoning of space science and technology.It is imperatively desired to high insulation materials with lightweight and extensive mechanical properties.Herein,a boron-silica-tantalum ternary hybrid phenolic aerogel(BSiTa-PA)with exceptional thermal stability,extensive mechanical strength,low thermal conductivity(49.6 mW m^(-1)K^(-1)),and heightened ablative resistance is prepared by an expeditious method.After extremely thermal erosion,the obtained carbon aerogel demonstrates noteworthy electromagnetic interference(EMI)shielding performance with an efficiency of 31.6 dB,accompanied by notable loading property with specific modulus of 272.8 kN·m kg^(-1).This novel design concept has laid the foundation for the development of insulation materials in more complex extreme environments.

Multi-objective microgrid optimal dispatching based on improved bird swarm algorithm

Multi-objective optimal dispatching schemes with intelligent algorithms are recognized as effective measures to promote the economics and environmental friendliness of microgrid applications.However,the low accuracy and poor convergence of these algorithms have been challenging for system operators.The bird swarm algorithm(BSA),a new bio-heuristic cluster intelligent algorithm,can potentially address these challenges;however,its computational iterative process may fall into a local optimum and result in premature convergence when optimizing small portions of multi-extremum functions.To analyze the impact of a multi-objective economic-environmental dispatching of a microgrid and overcome the aforementioned problems of the BSA,a self-adaptive levy flight strategy-based BSA(LF-BSA)was proposed.It can solve the dispatching problems of microgrid and enhance its dispatching convergence accuracy,stability,and speed,thereby improving its optimization performance.Six typical test functions were used to compare the LF-BSA with three commonly accepted algorithms to verify its excellence.Finally,a typical summer-time daily microgrid scenario under grid-connected operational conditions was simulated.The results proved the feasibility of the proposed LF-BSA,effectiveness of the multi-objective optimization,and necessity of using renewable energy and energy storage in microgrid dispatching optimization.

Fast ISAR imaging method based on scene segmentation

Although compressed sensing inverse synthetic aperture radar(ISAR) imaging methods are widely used in radar signal processing, its reconstructing time and memory storage space requirements are very high. The main reason is that large scene reconstruction needs a higher dimension of the sensing matrix. To reduce this limitation, a fast high resolution ISAR imaging method,which is based on scene segmentation for random chirp frequencystepped signals, is proposed. The idea of scene segmentation is used to solve the problems aforementioned. In the method,firstly, the observed scene is divided into multiple sub-scenes and then the sub-scenes are reconstructed respectively. Secondly, the whole image scene can be obtained through the stitching of the sub-scenes. Due to the reduction of the dimension of the sensing matrix, the requirement of the memory storage space is reduced substantially. In addition, due to the nonlinear superposition of the reconstructed time of the segmented sub-scenes, the reconstruction time is reduced, and the purpose of fast imaging is achieved.Meanwhile, the feasibility and the related factors which affect the performance of the proposed method are also analyzed, and the selection criterion of the scene segmentation is afforded. Finally,theoretical analysis and simulation results demonstrate the feasibility and effectiveness of the proposed method.

Developing a Transformation-Independent and Unbiased qPCR Assay to Rapidly Evaluate the Determinants of DNA Assembly Efficiency

Synthetic biology is moving in the direction of larger and more sophisticated design,which depends heavily on the efficient assembly of genetic modules.Conventional evaluation of the DNA assembly efficiency(AE)requires transformation,and the whole process requires up to 10 h and is susceptible to various interferences.To achieve rapid and reliable determination of the AE,an alternative transformation-independent method was established using a modified quantitative polymerase chain reaction(qPCR)assay.The AE is represented by the proportion of the ligated fragment,which can be determined within 3 h.This qPCR-based measurement was tested by the commonly used restriction ligation,Golden Gate assembly,and Gibson assembly for the assembly of two or more DNA pieces;the results correlated significantly with the AEs represented by the counting of the colony-forming units(CFUs).This method outperformed the CFU-based measurement by reducing the measuring bias and the random deviations that stem from the transformation process.The method was then employed to investigate the effects of terminal secondary structures on DNA assembly.The results revealed the major effects of the overall properties of the overlap sequence and the negative effects of hairpin structures on the AE,which are relevant for all assembly techniques that rely on homologous annealing of the terminal sequences.The qPCR-based approach presented here should facilitate the development of DNA assembly techniques and the diagnosis of inefficient assemblies.

Magnetic Phase Diagram of Cu4-xZnx(OH)6FBr Studied by Neutron-Diffraction and μSR Techniques

We systematically investigate the magnetic properties of Cu4-xZnx(OH)6FBr using the neutron diffraction and muon spin rotation and relaxation(μSR) techniques.Neutron-diffraction measurements suggest that the longrange magnetic order and the orthorhombic nuclear structure in the x=0 sample can persist up to x=0.23 and 0.43,respectively.The temperature dependence of the zero-field μSR spectra provides two characteristic temperatures,TA0 and Tλ,which are associated with the initial drop close to zero time and the long-time exponential decay of the muon relaxation,respectively.Comparison between TA0 and TM from previously reported magnetic-susceptibility measurements suggest that the former comes from the short-range interlayer-spin clusters that persist up to x=0.82.On the other hand,the doping level where Tλ becomes zero is about 0.66,which is much higher than threshold of the long-range order,i.e.,~0.4.Our results suggest that the change in the nuclear structure may alter the spin dynamics of the kagome layers and a gapped quantum-spin-liquid state may exist above x=0.66 with the perfect kagome planes.

An Approach to Dynamic Asymptotic Estimation for Hurst Index of Network Traffic

As an important parameter to describe the sudden nature of network traffic, Hurst index typically conducts behaviors of both self-similarity and long-range dependence. With the evolution of network traffic over time, more and more data are generated. Hurst index estimation value changes with it, which is strictly consistent with the asymptotic property of long-range dependence. This paper presents an approach towards dynamic asymptotic estimation for Hurst index. Based on the calculations in terms of the incremental part of time series, the algorithm enjoys a considerable reduction in computational complexity. Moreover, the local sudden nature of network traffic can be readily captured by a series of real-time Hurst index estimation values dynamically. The effectiveness and tractability of the proposed approach are demonstrated through the traffic data from OPNET simulations as well as real network, respectively.

Y染色体微缺失人群中Y-STR等位基因缺失模式分析

Y染色体短串联重复序列(Y-short tandem repeats, Y-STRs)已被广泛应用到DNA检验领域。然而,由于Y染色体存在较高的结构突变率,可能会导致部分Y-STR等位基因丢失甚至产生特殊的缺失模式,从而影响其在法医学中的应用。位于Y染色体长臂的无精子症因子(azoospermia factor, AZF)与精子发生有关,该区域微缺失可导致不育症。然而Y染色体微缺失人群是否存在特殊的Y-STR缺失模式仍有待研究。本文利用法医学上常用17个Y-STR探讨了85例Y染色体微缺失患者的Y-STR缺失模式。结果显示,单纯AZF a区缺失样本,均存在DYS439-DYS389I-DYS389II基因座无效扩增情况;单纯AZF b区或单纯AZF c区缺失样本存在DYS448基因座无效扩增;复合AZF b+c+d区缺失样本存在DYS385-DYS392-DYS448基因座无效扩增;复合AZFa+b+c+d区缺失样本存在DYS390-Y-GATA-H4-DYS385-DYS392-DYS448基因座无效扩增。因此,本研究结果提示Y-STR缺失模式与Y染色体微缺失有对应关系。

静电纺丝法制备POSS-(C_3H_6Cl)_8复合聚偏氟乙烯聚合物隔膜的结构与性能

为了提高锂离子电池的安全性,文中选择聚偏氟乙烯(PVDF)为聚合物基体,八氯丙基低聚倍半硅氧烷(POSS-(C_3H_6Cl)_8)为改性剂,通过静电纺丝法制备POSS-(C_3H_6Cl)_8复合PVDF聚合物隔膜(EPS)。表征了纺丝膜的形貌、力学性能,测试了电化学窗口和Li/LiFePO_4纽扣电池的充放电循环稳定性。结果表明,当POSS-(C_3H_6Cl)_8的加入量为10%时,静电纺丝纤维薄膜的拉伸强度和断裂伸长率分别比纯PVDF提高了106.4%和27.2%;室温下的离子传导率为3.8×10^(-3)S/cm,比纯PVDF提高了97.4%;电化学稳定窗口为5.7 V。用该聚合物隔膜组装的锂离子电池具有良好的循环稳定性和倍率性能。

利用CRISPR/Cas9系统构建FGF21基因敲除小鼠模型

成纤维细胞生长因子(fibroblast growth factors,FGFs)是细胞间的多功能信号分子,调节生物体的多种生理功能。FGF21作为一种重要的调控因子,对毛囊发育及生长周期具有重要作用。为研究FGF21基因对毛囊发育及生长周期的影响及作用机制,本研究通过构建靶向敲除FGF21基因的载体,体外将Cas9 m RNA和g RNA显微注射到FVB小鼠受精卵中,在小鼠FGF21基因的第1外显子上造成移码突变,从而获得FGF21基因敲除(knock out,KO)小鼠。通过测序鉴定F0代小鼠基因型,共获得3只FGF21等位基因敲除小鼠(Fgf21^(-/-));q RT-PCR和Western blotting结果表明,在Fgf21^(-/-)小鼠中未检测到FGF21 m RNA表达和FGF21蛋白表达;经脱毛再生及皮肤组织H&E染色发现,与野生型(wild type,WT)小鼠相比,Fgf21^(-/-)小鼠体重降低、器官组织未出现异常变化、毛发生长速度减慢、毛囊的直径和毛发的密度均减小。本研究利用CRISPR/Cas9技术成功构建了Fgf21^(-/-)小鼠模型,为后续研究FGF21基因在毛囊发育及生长周期中的功能提供了更好的动物模型。

cgVEGF164基因对小鼠毛囊生长的影响

血管内皮生长因子(vascular endothelial growth factor, VEGF)是一种二聚体糖蛋白,能够诱导毛囊血管内皮细胞的增殖和迁移,调节毛囊周围毛细血管生成,进而影响毛囊的生长发育。已知cgVEGF164是绒山羊VEGF-A基因的一种主要剪接变体,但cgVEGF164基因是否具有调控毛囊生长发育的作用目前尚不清楚。为初步探究cgVEGF164基因对毛囊生长的影响及其机制,本研究通过原核显微注射制备cgVEGF164转基因过量表达小鼠。通过HE染色法比较转基因小鼠和非转基因对照小鼠毛囊的直径和密度,利用WesternBlot检测小鼠背部皮肤中信号蛋白ERK1/2、AKT1、LEF1的磷酸化水平。本研究成功获得5只阳性cg VEGF164转基因小鼠(雌雄比为4:1,阳性率8.5%);与非转基因对照小鼠相比,转基因小鼠毛囊直径增大、密度增加;经检测转基因小鼠中ERK1/2、AKT1、LEF1的磷酸化水平均上调。结果表明,cgVEGF164基因具有促进小鼠毛囊生长的作用,推测该功能可能与cgVEGF164影响ERK1/2、AKT1和LEF1等信号蛋白的磷酸化有关。

Preparation of High-precision Electrospun Nanoair Filter Paper for Air Purification

Electrospinning technology has become a research hotspot becauseof its advantages, such as simple operation, low cost, large specific surfacearea, high porosity, and good fiber continuity. Here, a new type of compositenanoair filter paper was prepared using electrospinning technology. Toimprove the practicability of air filter base paper, phenolic resin was used as acuring agent to improve the strength. The results show that the electrospunnanoair filter paper with air filter paper as the receiving substrate andpolyvinyl alcohol (PVA) solution as the spinning solution excellentlyperformed in all aspects. The influence of the thickness (spinning time) of thePVA nanofiber membrane on the micromorphology, physical properties, andfiltration performance of the electrospun nanoair filter paper was analyzed.According to the ISO 5011-2014 standard, the initial resistance, filtrationefficiency, mean pore size, and dust capacity of the electrospun nanoair filterpaper were 77.3 Pa, 99.9941%, 3.50 μm, and 146 g/m^(2), respectively, when thespinning time was 15 min.

Effect of microbiome group on immune checkpoint inhibitors in treatment of gastrointestinal tumors

In recent years,immune checkpoint blockade(ICB)therapy has become an important treatment strategy for gastrointestinal tumors,however,it only benefits about 1/3 of patients.Since the microbiome has been shown to play an important role in the human body for a long time,a growing number of studies are focusing on its relationship to ICB therapy in cancer,specifically how intestinal microbes affect the efficacy of immune checkpoint inhibitors(ICIs)therapy in patients.On this basis,probiotic interventions,fecal microbiota transplantation(FMT),dietary interventions,and other methods which improve or maintain the structure of the intestinal flora have attracted widespread attention.This article discusses the four aspects of the microbiome,ICB,combined treatment of gastrointestinal tumors,and regulation of gut microbiome.Particularly,the discussion focuses on the contribution of probiotic intervention in improving the therapeutic effect of ICIs to prolong the survival time of patients and reduce the severity of immune-related adverse effects(irAEs).

Focused-ion-beam assisted technique for achieving high pressure by uniaxial-pressure devices

Uniaxial pressure or strain can introduce a symmetry-breaking distortion on the lattice and may alter the ground states of a material. Compared to hydrostatic pressure, a unique feature of the uniaxial-pressure measurements is that a tensile force can be applied and thus a “negative” pressure can be achieved. In doing so, both ends of the sample are usually glued on the frame of the uniaxial-pressure device. The maximum force that can be applied onto the sample is sometimes limited by the shear strength of the glue, the quality of the interface between the sample and the glue, etc. Here we use focused ion beam to reduce the width of the middle part of the sample, which can significantly increase the effective pressure applied on the sample. By applying this technique to a home-made piezobender-based uniaxial-pressure device, we can easily increase the effective pressure by one or two orders of magnitude as shown by the change of the superconducting transition temperature of an iron-based superconductor. Our method thus provides a possible way to increase the upper limit of the pressure for the uniaxial-pressure devices.

In-Plane Anisotropic Response to Uniaxial Pressure in the Hidden Order State of URu_(2)Si_(2)

We investigate the uniaxial-pressure dependence of resistivity for URu_(2−x)Fe_(x)Si_(2)samples with x=0 and 0.2,which host a hidden order(HO)and a large-moment antiferromagnetic(LMAFM)phase,respectively.For both samples,the elastoresistivityζshows a seemingly divergent behavior above the transition temperature T_(0)and a quick decrease below it.We find that the temperature dependence ofζfor both samples can be well described by assuming the uniaxial pressure effect on the gap or certain energy scale except forζ(110)of the x=0 sample,which exhibits a nonzero residual value at 0 K.We show that this provides a qualitative difference between the HO and LMAFM phases.Our results suggest that there is an in-plane anisotropic response to the uniaxial pressure that only exists in the hidden order state without necessarily breaking the rotational lattice symmetry.

Nonlocal Effects of Low-Energy Excitations in Quantum-Spin-Liquid Candidate Cu_(3)Zn(OH)_(6)FBr

We systematically study the low-temperature specific heats for the two-dimensional kagome antiferromagnet,Cu_(3)Zn(OH)_(6)FBr.The specific heat exhibits a T1.7 dependence at low temperatures and a shoulder-like feature above it.We construct a microscopic lattice model of Z_(2) quantum spin liquid and perform large-scale quantum Monte Carlo simulations to show that the above behaviors come from the contributions from gapped anyons and magnetic impurities.Surprisingly,we find the entropy associated with the shoulder decreases quickly with grain size d,although the system is paramagnetic to the lowest temperature.While this can be simply explained by a core-shell picture in that the contribution from the interior state disappears near the surface,the 5.9-nm shell width precludes any trivial explanations.Such a large length scale signifies the coherence length of the nonlocality of the quantum entangled excitations in quantum spin liquid candidate,similar to Pippard’s coherence length in superconductors.Our approach therefore offers a new experimental probe of the intangible quantum state of matter with topological order.

Camellia oil (Camellia oleifera Abel.) alleviates gastric injury induced by ethanol associated with modulation of gut microbiota in mice

Oil from Camellia oleifera Abel. seed is a popular edible oil in Asia, which has gained much attention for itsmedicinal applications on relieving various inflammation, however, the mechanism is still unknown. The presentstudy was to investigate the gastroprotective effect of camellia oil against ethanol-induced gastric mucosal injuryin mice. The results showed that camellia oil pretreatment significantly reduced gastric ulcer injury. A remarkableinhibited oxidative stress by reducing the concentration of malondialdehyde and a significant decrease of thelevels of pro-inflammatory factors in gastric tissue were observed in camellia oil pretreated group. In addition,camellia oil improved the diversity of gut microbiota and changed the community structure and composition byincreasing Bacteriodes and Dorea. And the feces metabolomics found that metabolism of cofactors and vitamins,and lipid, carbohydrate and amino acid metabolism were modulated by admiration of camellia oil. Takentogether, the findings of this study suggested that camellia oil could ease the ethanol-induced gastric mucosalinjury via the improvement of anti-oxidant and anti-inflammatory status, as well as the regulation of gutmicrobiota and its metabolites.

Impact of ozonation on disinfection byproducts formation from phenylalanine during chlorination

As a strong oxidizing agent,ozone is used in some water treatment facilities for disinfection,taste and odor control,and removal of organic micropollutants.Phenylalanine(Phe)was used as the target amino acid to comprehensively investigate variability of disinfection byproducts(DBPs)formation during chlorine disinfection and residual chlorine conditions subsequent to ozonation.The results showed that subsequent to ozonation,the typical regulated and unregulated DBPs formation potential(DBPsFP),including trichloromethane(TCM),dichloroacetonitrile(DCAN),chloral hydrate(CH),dichloroacetic acid(DCAA),trichloroacetic acid(TCAA),and trichloroacetamide(TCAcAm)increased substantially,by 2.4,3.3,5.6,1.2,2.5,and 6.0 times,respectively,compared with only chlorination.Ozonation also significantly increased the DBPs yield under a 2 day simulated residual chlorine condition that mimicked the water distribution system.DBPs formations followed pseudo first order kinetics.The formation rates of DBPs in the first 6 hr were higher for TCM(0.214 hr^(−1)),DCAN(0.244 hr^(−1)),CH(0.105 hr^(−1)),TCAcAm(0.234 hr^(−1)),DCAA(0.375 hr^(−1))and TCAA(0.190 hr^(−1))than thereafter.The peak DBPsFP of TCM,DCAN,CH,TCAcAm,DCAA,and TCAA were obtained when that ozonation time was set at 5–15 min.Ozonation times>30 min increased the mineralization of Phe and decreased the formation of DBPs upon chlorination.Increasing bromine ion(Br^(−1))concentration increased production of bromine-DBPs and decreased chlorine-DBPs formation by 59.3%–92.2%.Higher ozone dosages and slight alkaline favored to reduce DBP formation and cytotoxicity.The ozonation conditions should be optimized for all application purposes including DBPs reduction.

Kinetics of oxidation of dimethyl trisulfide by potassium permanganate in drinking water

Metabolites of algae such as geosmin, 2- methylisoborneol etc. are reported to induce pungent odors into drinking water and attract additional scientifc attention. Recently, in China, taste and odor outbreaks in drinking water supply have become increasingly common. In source water affected by eutrophication, dimethyl trisulfide, speculated to be produced by decayed algae, was found to be the source of taste and odor issues and can be removed effectively by usual oxidation agents. In this experimental study, batch scale tests were carried out focusing on the removal of dimethyl trisulfide. Reaction kinetics of dimethyl trisulfide oxidized by potassium permanganate in water had been studied; influence factors such as pH, organic substrate, other existed taste, and odor contaminant in equivalent concentration were also dis- cussed. Results showed that dimethyl trisulfide can be removed by potassium permanganate efficiently; the ratio can reach more than 70% with oxidant dosage of 4 mg. L~ and contact time prolonged to 120 min. The dimethyl trisulfide decomposition followed a second-order kinetics pattern with a rate constant k -- 0.00213 L.（min.mg）-1. Typically, the degradation rate of dimethyl trisulfide was increased with the increasing KMnO4 dosage, but dramatically dropped with the increasing levels of humic acid （1.8-4.5 mg. L-1） and other odor-causing compounds （e.g. fl-cyclocitral, 0-1886.0 pg.L-1）. Solution pH （5.2- 9.0） and initial dimethyl trisulfide concentration did not significantly affected the degradation. This study demon- strates that KMnO4 oxidation is an effective option to remove dimethyl trisulfide from water.

Large-scale preparation of high-performance boron nitride/aramid nanofiber dielectric composites

Dielectric polymers featuring high thermal conductivity,excellent mechanical,and stable dielectric properties over a broad temperature range have attracted extensive scientific attention.In this work,a large-scale,layered film was fabricated using blade-coating approach,which integrated aramid nanofibers(ANFs)and boron nitride nanosheets(BNNSs)through a typical solgel transformation procedure.The as-prepared film with 20 wt.%BNNS displays high thermal conductivity(14.03 W·m^(−1)·K^(−1)),103-fold higher than pure ANF film,attributing to massive continuous thermal conduction pathway between BNNSs so as to facilitate fast phonon transmission.The film boasts excellent mechanical properties(stress 97.14±5.17 MPa,strain 19.36±0.35%),high degradation temperature(~542℃),a moderate dielectric constant(~6.9 at 104 Hz),together with low dielectric loss(~0.026 at 104 Hz).Meanwhile,the film reveals high breakdown voltage(310 MV·m^(−1))and volume resistivity(1013Ω·cm).Notably,these dielectric properties remain largely unchanged over a wide temperature range(25 to 200℃).