Transplantation of fibrin-thrombin encapsulated human induced neural stem cells promotes functional recovery of spinal cord injury rats through modulation of the microenvironment

Recent studies have mostly focused on engraftment of cells at the lesioned spinal cord,with the expectation that differentiated neurons facilitate recovery.Only a few studies have attempted to use transplanted cells and/or biomaterials as major modulators of the spinal cord injury microenvironment.Here,we aimed to investigate the role of microenvironment modulation by cell graft on functional recovery after spinal cord injury.Induced neural stem cells reprogrammed from human peripheral blood mononuclear cells,and/or thrombin plus fibrinogen,were transplanted into the lesion site of an immunosuppressed rat spinal cord injury model.Basso,Beattie and Bresnahan score,electrophysiological function,and immunofluorescence/histological analyses showed that transplantation facilitates motor and electrophysiological function,reduces lesion volume,and promotes axonal neurofilament expression at the lesion core.Examination of the graft and niche components revealed that although the graft only survived for a relatively short period(up to 15 days),it still had a crucial impact on the microenvironment.Altogether,induced neural stem cells and human fibrin reduced the number of infiltrated immune cells,biased microglia towards a regenerative M2 phenotype,and changed the cytokine expression profile at the lesion site.Graft-induced changes of the microenvironment during the acute and subacute stages might have disrupted the inflammatory cascade chain reactions,which may have exerted a long-term impact on the functional recovery of spinal cord injury rats.

VMCTE:Visualization-BasedMalware Classification Using Transfer and Ensemble Learning

The Corona Virus Disease 2019(COVID-19)effect has made telecommuting and remote learning the norm.The growing number of Internet-connected devices provides cyber attackers with more attack vectors.The development of malware by criminals also incorporates a number of sophisticated obfuscation techniques,making it difficult to classify and detect malware using conventional approaches.Therefore,this paper proposes a novel visualization-based malware classification system using transfer and ensemble learning(VMCTE).VMCTE has a strong anti-interference ability.Even if malware uses obfuscation,fuzzing,encryption,and other techniques to evade detection,it can be accurately classified into its corresponding malware family.Unlike traditional dynamic and static analysis techniques,VMCTE does not require either reverse engineering or the aid of domain expert knowledge.The proposed classification system combines three strong deep convolutional neural networks(ResNet50,MobilenetV1,and MobilenetV2)as feature extractors,lessens the dimension of the extracted features using principal component analysis,and employs a support vector machine to establish the classification model.The semantic representations of malware images can be extracted using various convolutional neural network(CNN)architectures,obtaining higher-quality features than traditional methods.Integrating fine-tuned and non-fine-tuned classification models based on transfer learning can greatly enhance the capacity to classify various families ofmalware.The experimental findings on the Malimg dataset demonstrate that VMCTE can attain 99.64%,99.64%,99.66%,and 99.64%accuracy,F1-score,precision,and recall,respectively.

Motor neuron replacement therapy for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a motor neuron degenerative disease that is also known as Lou Gehrig’s disease in the United States,Charcot’s disease in France,and motor neuron disease in the UK.The loss of motor neurons causes muscle wasting,paralysis,and eventually death,which is commonly related to respiratory failure,within 3-5 years after onset of the disease.Although there are a limited number of drugs approved for amyotrophic lateral sclerosis,they have had little success at treating the associated symptoms,and they cannot reverse the course of motor neuron degeneration.Thus,there is still a lack of effective treatment for this debilitating neurodegenerative disorder.Stem cell therapy for amyotrophic lateral sclerosis is a very attractive strategy for both basic and clinical researchers,particularly as transplanted stem cells and stem cell-derived neural progenitor/precursor cells can protect endogenous motor neurons and directly replace the lost or dying motor neurons.Stem cell therapies may also be able to re-establish the motor control of voluntary muscles.Here,we review the recent progress in the use of neural stem cells and neural progenitor cells for the treatment of amyotrophic lateral sclerosis.We focus on MN progenitor cells derived from fetal central nervous system tissue,embryonic stem cells,and induced pluripotent stem cells.In our recent studies,we found that transplanted human induced pluripotent stem cell-derived motor neuron progenitors survive well,differentiate into motor neurons,and extend axons into the host white matter,not only in the rostrocaudal direction,but also along motor axon tracts towards the ventral roots in the immunodeficient rat spinal cord.Furthermore,the significant motor axonal extension after neural progenitor cell transplantation in amyotrophic lateral sclerosis models demonstrates that motor neuron replacement therapy could be a promising therapeutic strategy for amyotrophic lateral sclerosis,particularly as a variety of stem cell derivatives,including induced pluripotent stem cells,are being considered for clinical trials for various diseases.

Effect of Small Addition of Sc on the Microstructural Evolution in Al-15Ag Alloy

The effect of small addition of Sc on the microstructural evolution in Al-15Ag alloy was investigated by Monte Carlo simulation and transmission electron microscopy （TEM）. Monte Carlo simulation results indicate that Ag clustering is suppressed by the addition of Sc during the initial ageing stage, and there is a little chemical repulsion between Ag atoms and Sc atoms. TEM observations show that the morphology of γ′ precipitation can be modified by the small addition of Sc, which does result in a refinement of γ′ precipitates in Al-15Ag-0.2Sc. The mechanism by which trace Sc affect the microstructure is to reduce the ledge density of γ′precipitates.

通讯基础设施对物流业的空间溢出机制与溢出效应研究

本文基于省际面板数据,在对全国物流业发展水平的空间相关性及空间集群检测的基础上,探析了通讯基础设施对物流业的空间溢出机制,并构建动态双固定效应空间杜宾模型实证估计了通讯基础设施对物流业的空间溢出效应。研究结果发现:(1)我国物流业存在稳定的空间集聚特点与正向空间溢出效应,且空间集群检测表明全国物流业发展存在显著的空间异质性与持续性的特征,北京、天津、江苏、浙江等发达地区始终处于HH类型,始终处于LL类型的地区大多是中西部地区。(2)动态双固定效应空间杜宾模型估计发现电话普及率与互联网普及率均在10%显著性水平上对物流业发展有明显的空间溢出效应,并运用偏微分法研究发现两者也均在10%显著性水平上对物流业发展有显著的短期溢出效应。据此表明,通讯基础设施对物流业存在空间溢出效应,且其对物流业主要呈现出显著的短期溢出效应。(3)分地区估计发现通讯基础设施对物流业的溢出效应有明显的地区异质性,表现在东部地区通讯基础设施短期与长期均存在显著的正向溢出效应,而中西部地区只有电话存在显著的短期溢出效应。据此,在“新基建”战略推进期提出驱动通讯基础设施健康发展的治理路径,以促进物流业进一步优化升级。

Small amount but big impact:Trace oxygen interstitially inserted PtCu alloys by microalloying for efficient oxygen reduction catalysis

The introduction of small size non-metal elements(e.g.,oxygen)into solid solution alloys may be a promising strategy for fabricating efficient Pt-based catalysts with high activity and stability toward oxygen reduction reaction(ORR).Herein,oxygen interstitially inserted PtCu(O-PtCu)alloys are firstly designed by an oxygen-microalloying strategy,through ultraviolet(UV)irradiation-assisted galvanic replacement in an aqueous solution containing H_(2)PtCl_(6) and Cu_(2)O nanowires as sacrificial templates.The obtained O-PtCu alloys feature a typical face-centered cubic(FCC)structure with majority Pt,Cu atoms as building bricks and trace interstitial oxygen(1.65 wt.%)existed in the octahedral sites surrounding Cu atoms,leading to a short-range disordered structure.The alloy reaches a recorded half-wave potential of 0.96 V(vs.reversible hydrogen electrode(RHE))and mass activity of 0.48 A·mgPt^(−1),much higher than those of commercial Pt/C.During the accelerated degradation test(ADT),the mass activity lost only 4.2%after 10k cycles,while the commercial Pt/C lost 66.7%under the same conditions.Compared with pure Pt and undoped PtCu alloy,the remarkably improved performance can be attributed to the lattice distortion and energy band reconstruction caused by the interstitial oxygen atoms in form of Cu–O bonds.Moreover,the stable Cu–O bonds delay the possible place exchange between surface Pt atoms and surface-adsorbed oxygen species,thereby hindering Pt dissolution,providing a new paradigm to address Pt degradation issue.Therefore,the introduction of interstitial oxygen into Pt-based alloys may be a facile and smart strategy for the development of advanced Pt-based alloys electrocatalysts.

Global video object segmentation with spatial constraint module

We present a lightweight and efficient semisupervised video object segmentation network based on the space-time memory framework.To some extent,our method solves the two difficulties encountered in traditional video object segmentation:one is that the single frame calculation time is too long,and the other is that the current frame’s segmentation should use more information from past frames.The algorithm uses a global context(GC)module to achieve highperformance,real-time segmentation.The GC module can effectively integrate multi-frame image information without increased memory and can process each frame in real time.Moreover,the prediction mask of the previous frame is helpful for the segmentation of the current frame,so we input it into a spatial constraint module(SCM),which constrains the areas of segments in the current frame.The SCM effectively alleviates mismatching of similar targets yet consumes few additional resources.We added a refinement module to the decoder to improve boundary segmentation.Our model achieves state-of-the-art results on various datasets,scoring 80.1%on YouTube-VOS 2018 and a J&F score of 78.0%on DAVIS 2017,while taking 0.05 s per frame on the DAVIS 2016 validation dataset.

自体诱导神经干细胞来源的多巴胺能神经前体细胞完成首例帕金森病患者脑内移植

Parkinson's disease(PD)is the second most common neurodegenerative disease,affecting around 1.0%of the population over 65 years of age[1].In China,there are estimated to be more than 3 million PD patients,with each year about 100,000 PD patients being newly diagnosed.Along with China stepping into an aging society,it was estimated that in 2030,there would be around 5 million PD patients in China alone,which would create huge socioeconomic burdens on patients and their families.

新型热处理调控Al-Cu-Mg合金残余应力的工艺和机理

对Al-Cu-Mg合金进行一种能消减残余应力的新型热处理,使用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射等手段分析残余应力并测试力学性能,研究了这种合金的微观组织结构和性能。结果表明:新型热处理使Al-Cu-Mg合金的残余应力消减率达到92.7%(与固溶态铝合金相比),并得到优良的强塑性配合(屈服强度达到463.6 MPa,抗拉强度达到502.5 MPa,伸长率达到12.7%)。微观组织的分析结果表明:在进行新型热处理的合金中S'相比用传统热处理的更为细小、分布更均匀,由S'相析出的共格应力场与淬火残余应力场叠加使合金残余应力大幅度降低,使合金的综合性能较高。

Accelerated generation of oligodendrocyte progenitor cells from human induced pluripotent stem cells by forced expression of Sox10 and Olig2

Oligodendrocyte progenitor cells(OPCs) hold great promise for treatment of dysmyelinating disorders, such as multiple sclerosis and cerebral palsy. Recent studies on generation of human OPCs mainly use human embryonic stem cells(hESCs) or neural stem cells(NSCs) as starter cell sources for the differentiation process. However, NSCs are restricted in availability and the present method for generation of oligodendrocytes(OLs) from ESCs often requires a lengthy period of time. Here, we demonstrated a protocol to efficiently derive OPCs from human induced pluripotent stem cells(hiPSCs) by forced expression of two transcription factors(2TFs), Sox10 and Olig2. With this method, PDGFRα+ OPCs can be obtained in 14 days and O4^+ OPCs in 56 days.Furthermore, OPCs may be able to differentiate to mature OLs that could ensheath axons when co-cultured with rat cortical neurons. The results have implications in the development of autologous cell therapies.

Passive-Event-Assisted Approach for the Localizability of Large-Scale Randomly Deployed Wireless Sensor Network

Localizability in large-scale, randomly deployed Wireless Sensor Networks(WSNs) is a classic but challenging issue. To become localizable, WSNs normally require extensive adjustments or additional mobile nodes. To address this issue, we utilize occasional passive events to ease the burden of localization-oriented network adjustment. We prove the sufficient condition for node and network localizability and design corresponding algorithms to minimize the number of nodes for adjustment. The upper bound of the number of adjusted nodes is limited to the number of articulation nodes in a connected graph. The results of extensive simulations show that our approach greatly reduces the cost required for network adjustment and can thus provide better support for the localization of large-scale sparse networks than other approaches.