Use of FK506 and bone marrow mesenchymal stem cells for rat hind limb allografts

Dark Agouti rat donor hind limbs were orthotopically transplanted into Lewis rat recipients to verify the effects of bone marrow mesenchymal stem cells on neural regeneration and functional recovery of allotransplanted limbs in the microenvironment of immunotolerance, bone marrow mesenchymal stem cells were intramuscularly （gluteus maximus） injected with FK506 （tacrolimus） daily, and were transplanted to the injured nerves. Results indicated that the allograft group not receiving therapy showed severe rejection, with transplanted limbs detaching at 10 days after transplantation with complete necrosis. The number of myelinated axons and Schwann cells in the FK506 and FK506 ＋ bone marrow mesenchymal stem cells groups were significantly increased. We observed a lesser degree of gastrocnemius muscle degeneration, and increased polymorphic fibers along with other pathological changes in the FK506 ＋ bone marrow mesenchymal stem cells group. The FK506 ＋ bone marrow mesenchymal stem cells group showed significantly better recovery than the autograft and FK506 groups. The results demonstrated that FK506 improved the immune microenvironment. FK506 combined with bone marrow mesenchymal stem cells significantly promoted sciatic nerve regeneration, and improved sensory recovery and motor function in hind limb allotransplant.

云计算安全威胁及防护研究

云计算已经成为我国数字经济发展的重要支撑基础,云计算安全状况直接关系到我国经济发展前景。在国家网络安全等级保护2.0标准下,本文针对云计算面临的安全威胁,依据云计算安全防护的原则,从云计算安全保障框架、云计算安全平台框架体系提出对云计算安全问题的解决方案。

典型有机固废厌氧消化微生物研究现状与发展方向

经过人工富集和驯化的兼性和严格厌氧微生物是厌氧消化工艺的核心。不同厌氧消化体系中存在的问题大多可以通过改变微生物群落的代谢活性来得到有效改善。得益于微生物组学检测技术的快速发展,对厌氧消化系统中微生物多样性的认识获得了极大的拓展,同时在微生物类群间、微生物与环境的互作关系研究方面也取得了一系列新的进展。然而,有机固废厌氧消化系统中,各种微生物以及微生物和物质的相互作用构成了更为复杂的代谢网络,所以目前对这些互作关系的解析尚不完善。本文重点关注了厌氧消化过程中的典型菌群互作关系,阐述了典型有机固废厌氧消化系统中存在的问题及微生物在其中发挥的作用,最后,立足于现有组学技术推动的微生物组研究进展,对未来有机固废厌氧消化系统微生物组的研究提出展望。

改变增益层厚度实现宽波段波长可调谐有机固体激光器

低成本连续可调谐激光器在光通讯领域有着广泛的应用前景.本文研究了一种通过改变增益层厚度来连续调谐有机固体激光器激光波长的简便方法.在制备过程中可以通过旋涂速度来有效地控制增益层的厚度.我们在分布反馈(DFB)光栅和平面波导器件结构中分别实现了激光和放大自发辐射(ASE)的波长连续调谐.在DFB激光器中,通过改变薄膜厚度实现波长调谐范围可达38 nm;同时,在平面波导结构中也获得了37 nm的调谐范围.可见,该方法可以在一定范围内自由地设置或调整激光波长,以满足具有特定用途的不同结构的激光器件.此外,增益层厚度的改变对器件的性能并没有产生影响,仍实现了低阈值、高增益的光放大特性.研究结果表明,通过增益层厚度的改变可以灵活简单地调谐激光波长,这为低成本、连续和快速可调谐激光光源的制备提供了一种简单可行的方法.

A LINE SEARCH FILTER SECANT METHOD FOR NONLINEAR EQUALITY CONSTRAINED OPTIMIZATION

This paper formulates and analyzes a line search method for general nonlinear equalityconstrained optimization based on filter methods for step acceptance and secant methods for searchdirection.The feature of the new algorithm is that the secant algorithm is used to produce a searchdirection,a backtracking line search procedure is used to generate step size,some filtered rules areused to determine step acceptance,second order correction technique is used to reduce infeasibility andovercome the Maratos effect.Global convergence properties of this method are analyzed:under mildassumptions it is showed that every limit point of the sequence of iterates generated by the algorithmis feasible,and that there exists at least one limit point that is a stationary point for the problem.Moreover,it is also established that the Maratos effect can be overcome in our new approach by addingsecond order correction steps so that fast local superlinear convergence to a second order sufficient localsolution is achieved.Finally,the results of numerical experiments are reported to show the effectivenessof the line search filter secant method.

Towards intrinsically pure graphene grown on copper

The state-of-the-art semiconductor industry is built on the successful production of silicon ingot with extreme purity as high as 99.999999999%,or the so-called"eleven nines".The coming high-end applications of graphene in electronics and optoelectronics will inevitably need defect-free pure graphene as well.Due to its two-dimensional(2D)characteristics,graphene restricts all the defects on its surface and has the opportunity to eliminate all kinds of defects,i.e.,line defects at grain boundaries and point or dot defects in grains,and produce intrinsically pure graphene.In the past decade,epitaxy growth has been adopted to grow graphene by seamlessly stitching of aligned grains and the line defects at grain boundaries were eliminated finally.However,as for the equally common dot and point defects in graphene grain,there are rare ways to detect or reduce them with high throughput and efficiency.Here,we report a methodology to realize the production of ultrapure graphene grown on copper by eliminating both the dot and point defects in graphene grains.The dot defects,proved to be caused by the silica particles shedding from quartz tube during the high-temperature growth,were excluded by a designed heat-resisting box to prevent the deposition of particles on the copper surface.The point defects were optically visualized by a mild-oxidation-assisted method and further reduced by etching-regrowth process to an ultralow level of less than 1/1,000 μm^(2).Our work points out an avenue for the production of intrinsically pure graphene and thus lays the foundation for the large-scale graphene applications at the integrated-circuit level.

the National Natural Science Foundation of China(41877029,41961130383);Royal SocietyNewton Advanced Fellowship(NAF\R1\191017);Wuhan Science and Technology Bureau(2019020701011469).

Due to the tremendous diversity of microbial organisms in topsoil,the estimation of saturated richness in a belowground ecosystem is still challenging.Here,we intensively surveyed the 16S rRNA gene in four 1 m2 sampling quadrats in a typical grassland,with 141 biological or technical replicates generating over 11 million sequences per quadrat.Through these massive data sets and using both non-asymptotic extrapolation and non-parametric asymptotic approaches,results revealed that roughly 15919±193,27193±1076 and 56985±2347 prokaryotic species inhabited in 1 m2 topsoil,classifying by DADA2,UPARSE(97%cutoff)and Deblur,respectively,and suggested a huge difference among these clustering tools.Nearly 500000 sequences were required to catch 50%species in 1 m2,while any estimator based on 500000 sequences would still lose about a third of total richness.Insufficient sequencing depth will greatly underestimate both observed and estimated richness.At least~911000,~3461000,and~1878000 sequences were needed for DADA2,UPARSE,and Deblur,respectively,to catch 80%species in 1 m2 topsoil,and the numbers of sequences would be nearly twice to three times on this basis to cover 90%richness.In contrast,α-diversity indexes characterized by higher order of Hill numbers,including Shannon entropy and inverse Simpson index,reached saturation with fewer than 100000 sequences,suggesting sequencing depth could be varied greatly when focusing on exploring differentα-diversity characteristics of a microbial community.Our findings were fundamental for microbial studies that provided benchmarks for the extending surveys in large scales of terrestrial ecosystems.

A rare case of plexiform angiomyxoid myofibroblastic tumor in the stomach which was diagnosed at the earliest stage in the literature

Plexiformangiomyxoid myofibroblastic tumor(PAMT)is a rare gastric mesenchymal entity with a peculiar plexiform pattern,bland spindle cells and myxoid stroma rich in arborizing blood vessels.Here we report a 44-year-old Chinese woman with PAMT.Initially she was admitted for removal of a gastric antral‘polyp’found on a routine examination 5 months previously.Our gastroscopy showed a 0.80.8cm polyp-like mass in the antrum which protruded into the lumen.Endoscopic submucosal dissection(ESD)was performed to remove this mass en bloc.The specimen was carefully examined by pathologists,and the correct diagnosis of PAMT was finally made.The tumor in this case depicted typical histopathological and immunohistochemical features of gastric PAMT.This PAMT was not only the smallest on endoscopic examination in the literature but also—unlike the already reported PAMTs—exhibited a focal hyperechogenic lesion on endoscopic ultrasonography(EUS).This information highlights its value on how to identify a PAMT at its early stage.

Growth,coalescence,and etching of two-dimensional overlayers on metals modulated by near-surface Ar nanobubbles

The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demonstrate that the overlayer–substrate interaction can be tuned by doping near-surface Ar nanobubbles.The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles,accompanying by an“anisotropic to isotropic”growth transformation.On the substrate containing near-surface Ar,the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference,and thus,the morphology of the two-dimensional(2D)overlayer exhibits a round-shape.Especially,the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction,which is barely observed in the synthesis of 2D materials.This can be attributed to the immigration lifetime and diffusion rate of growth species,which depends on the overlayer–substrate interaction and the surface catalysis.Furthermore,the“round to hexagon”morphological transition is achieved by etching-regrowth,revealing the inherent growth kinetics under quasi-freestanding conditions.These findings provide a novel promising way to modulate the growth,coalescence,and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer–substrate interaction,which contributes to optimization of large-scale production of 2D material crystals.

Soil microbiome mediated nutrients decline during forest degradation process

Degradation succession in forests is an important and serious land use/cover change problem in ecology,and during these processes soil microbial communities mediate the recycling of most important nutrients.To reveal the effect of degradation succession processes on soil microbial community diversity,structure,and species interrelationships,we collected abundant samples(21 per vegetation type)in broad-leaved forest,coniferous forest,and meadow to observe the microbial community dynamics.The results showed that diversity and structure of soil prokaryotic and fungal communities responded differently to different forest degradation processes,diversity of soil microbial communities increased during degradation processes.Soil microbial communities abundance changes may indicate that prokaryotic communities showed a living strategies change as an ecological adaption to harsh conditions during forest degradation process.While for fungal communities,their abundance changes may indicate that environmental selection pressure and plant selectivity during forest degradation process.Changes in soil prokaryotic communities and fungal communities were both correlated with soil carbon and nitrogen loss.The soil microbial interaction network analysis indicated more complex species interrelationships formed due to the loss of soil nutrients during degradation succession processes,suggesting soil microbial communities might form more complex and stable networks to resist the external disturbance of soil nutrient loss.All results suggested soil microorganisms,including bacteria,archaea and fungi,all involved in the soil nutrient decline during the forest degradation process.