0.05 T MRI for whole body

Recently,a study on a 0.05 T,low-cost,low-power,and computing-driven shielding-free ultra-low-field(ULF)magnetic resonance imaging(MRI)scannerwas published.This work enhances the image quality of MRI and reduces the scanning time based on deep learning methods,which is of great significance to enhancing the popularization and availability of MRI[1](https://www.science.org/doi/abs/10.1126/science.adm7168).

Drying kinetics of soy protein isolate-corn starch film during preparation and its moisture adsorption characteristics during storage

To better understand the mass transfer process of moisture in the soy protein isolate-corn starch(SPI-CS)films during preparation and storage process,the drying kinetics model of SPI-CS films with different formation conditions during the drying process and the moisture adsorption characteristics of the SPI-CS films under different humidity conditions were investigated.Within the range of experimental conditions,the moisture migration rule in the SPI-CS films during the drying preparation was combined with the Page model which was expressed as MR=exp(-kt^(n)).It was found that the adsorption equilibrium needed shorter time(about 3 h)when the SPI-CS films existed in the environment with lower humidity(RH<54%).Additionally,the secondorder adsorption kinetic equation was successful to describe the moisture adsorption characteristic of the SPICS films during storage under different humidity conditions.

Family-level diversity of extracellular proteases of sedimentary bacteria from the South China Sea

Protease-producing bacteria and their extracellular proteases are key players in degrading organic nitrogen to drive marine nitrogen cycling and yet knowledge on both of them is still very limited. This study screened protease-producing bacteria from the South China Sea sediments and analyzed the diversity of their extracellular proteases at the family level through N-terminal amino acid sequencing. Results of the 16 S rRNA gene sequence analysis showed that all screened protease-producing bacteria belonged to the class Gammaproteobacteria and most of them were affiliated with different genera within the orders Alteromonadales and Vibrionales. The Nterminal amino acid sequence analysis for fourteen extracellular proteases from fourteen screened bacterial strains revealed that all these proteases belonged to the M4 family of metalloproteases or the S8 family of serine proteases. This study presents new details on taxa of marine sedimentary protease-producing bacteria and types of their extracellular proteases, which will help to comprehensively understand the process and mechanism of the microbial enzymatic degradation of marine sedimentary organic nitrogen.

The normal cell proliferation and wound healing effect of polysaccharides from Ganoderma amboinense

To study the cell proliferation and wound healing activity of polysaccharides from Ganoderma amboinense(GAMPS),the polysaccharide was extracted by water extraction and alcohol precipitation method,and its monosaccharide composition and molecular weight were analyzed.The effects of different concentrations of GAMPS on the cell proliferation were determined by cell survival rate test,and the wound healing ability of GAMPS to NIH/3T3 cells was detected.The preliminary evaluation of the antioxidant ability of GAMPS was conducted by the oxygen radical absorbance capacity(ORAC).The results showed that the GAMPS was composed of glucose,mannose,and galactose at a molar ratio of 67.62:14.07:7.50,and the weightaverage molecular weights were 5.439×10^(6) and 1.704×10^(5) g/mol by using high-performance gel-permeation chromatography-multiple angle laser scatter(HPGPC-MALS)analysis.GAMPS(0.2μg/μL)showed the strongest proliferation ability to THP-1 cells,with cell survival rate of 178.7%.The wound healing effect of GAMPS(0.1μg/μL)was obvious on NIH/3T3 and 3.75μg/μL of GAMPS showed the strongest total antioxidant ability.All the results indicate that GAMPS promotes cell proliferation,and has cell wound healing effect and strong antioxidant activity.The results provide theoretical foundation for the development and utilization of GAMPS.

Tubular/helical architecture construction based on rolled-up AlN nanomembranes and resonance as optical microcavity

Aluminum nitride(AlN)has attracted a great amount of interest due to the fact that these group III–V semiconductors present direct band gap behavior and are compatible with current micro-electro-mechanical systems.In this work,three dimensional(3D)AlN architectures including tubes and helices were constructed by rolling up AlN nanomembranes grown on a silicon-on-insulator wafer via magnetron sputtering.The properties of the AlN membrane were characterized through transmission electron microscopy and X-ray diffraction.The thickness of AlN nanomembranes could be tuned via the RIE thinning method,and thus micro-tubes with different diameters were fabricated.The intrinsic strain in AlN membranes was investigated via micro-Raman spectroscopy,which agrees well with theory prediction.Whispering gallery mode was observed in AlN tubular optical microcavity in photoluminescence spectrum.A postprocess involving atomic layer deposition and R6G immersion were employed on as-fabricated AlN tubes to promote the Q-factor.The AlN tubular micro-resonators could offer a novel design route for Si-based integrated light sources.In addition,the rolled-up technology paves a new way for AlN 3D structure fabrication,which is promising for AlN application in MEMS and photonics fields.

Simple hybrid dithiafulvenes-triphenylamine systems as dopant-free hole-transporting materials for efficient perovskite solar cells

Two extended hybrid conjugated systems based on a triphenylamine(TPA) core with two and three peripheral 1,4-dithiafulvenes(DTF) units coded WH-2 and WH-3 as hole-transporting materials(HTMs) applied in perovskite solar cells(PSCs) are synthesized by facile one-step reaction in good yield over 75%. DTF unit as electron donor can enhance the electron donating ability and the fusion of benzenic ring of TPA with DTF unit may lead to reinforced intermolecular interactions in the solid state. In addition,WH-2 and WH-3 exhibit a pyramid shape containing partial planarity and quasi three-dimensionality features, which is also conducive to enhancing the π-π stacking of molecules in the solid state. The above-mentioned structural characteristics make the two HTMs have good hole mobilities. As a result,WH-2 and WH-3 obtained the high intrinsic hole mobilities of 4.69 × 10^(-4)and 2.18 × 10^(-3)cm^(2)V^(-1)s^(-1)respectively. Finally, the power conversion efficiencies(PCEs) of PSCs with WH-2 and WH-3 as cost-effective dopant-free HTMs are 15.39% and 19.22% respectively and the PCE of PSC with WH-3 is on a par with that of PSC with Li-TFSI/t-BP doped Spiro-OMe TAD(19.67%).

CONSTRUCTION OF IMPROVED BRANCHING LATIN HYPERCUBE DESIGNS

In this paper,we propose a new method,called the level-collapsing method,to construct branching Latin hypercube designs(BLHDs).The obtained design has a sliced structure in the third part,that is,the part for the shared factors,which is desirable for the qualitative branching factors.The construction method is easy to implement,and(near)orthogonality can be achieved in the obtained BLHDs.A simulation example is provided to illustrate the effectiveness of the new designs.

Chelation of lithium ion with crown ether for eliminating adverse effects caused by Li-TFSI/tBP doping system in Spiro-OMeTAD

Lithium bis(trifluoromethanesulfonyl)imide(Li-TFSI)/4-tert-butylpyridine(tBP)is a classic doping system for the hole transport material Spiro-OMeTAD in typical n-i-p structure perovskite solar cells(PSCs),but this system will cause many problems such as high hygroscopicity,Li+migration,pinholes and so on,which hinder PSC from maintaining high efficiency and stability for long-term.In this work,an effective strategy is demonstrated to improve the performance and stability of PSC by replacing t BP with 12-crown-4.The chelation of 12-crown-4 with Li+not only improves the doping effect of Li-TFSI,but also perfectly solves the problems caused by the Li-TFSI/tBP system.The PSC based on this strategy achieved a champion power conversion efficiency(PCE)over 21%,which is significantly better than the pristine device(19.37%).More importantly,the without encapsulated device based on Li-TFSI/12-crown-4 still maintains 87%of the initial PCE even after 60 days exposure in air,while the pristine device only maintains 22%of the initial PCE under the same aging conditions.This strategy paves a novel way for constructing efficient and stable PSCs.

胡154区长4＋5油层组水淹层解释方法研究

注水开发是提高岩性油气层采收率的一种有效方法,后期井网加密调整更是为了动用剩余油,进一步提高油藏采收率的有效方法.但由于长期的注水开发,部分储层已经水淹或者严重水淹,由于注入水进入地层,导致地层水矿化度变得复杂,不同水淹层测井曲线形态呈现多样性,解释难度非常大.经过对胡154区长4＋5油层组水淹层特征研究,总结出3种水淹层解释方法：新老井电阻率对比法、测井曲线形态法、电阻率曲线重构法.2017年通过3种方法综合应用,胡154区长4＋5油层组加密调整井解释符合率达92.2%,取得了较好的应用效果.

Systemic Risk in Chinese Commodity Futures Markets: A Graph Theory Analysis

This paper sets out to explore the contagion of systemic risk in Chinese commodity futures market based on specific tools of the graph-theory.More precisely,we use minimum spanning trees as a way to identify the most probable path for the transmission of prices shocks.In the sample of 30 kinds of Chinese commodity futures,we construct the MST and obtain the most probable and the shortest path for the transmission of a prices shock.We find that metal futures play an important role in commodity futures market and copper stands at the heart of the system(The core position of the system is very important for the transmission of system risk).And our results also reveal that when the risk occurs,the MST structure becomes smaller,leading to the most effective transmission path of risk becomes shorter.

Facile semisynthesis of histone H3 enables nucleosome probes for investigation of histone H_(3)K79 modifications

Histone H3K79 modifications are essential to regulate chromatin structure and gene transcription,but understanding of the molecular mechanisms is limited.Because H3K79 is at globular domain,short histone peptide cannot mimic H3K79 in chromatin.Instead,reconstituted nucleosome-based chemical tools are ideally used to investigate H3K79 modifications.In consequence,H3K79-modified histone H3 with additional chemical handles are required,but such synthesis is challenging and laborious.Here we report a facile semisynthesis method that enables multifunctional histone H3 readily available.H3K79-containing fragment is short for straight peptide synthesis that was later ligated to recombinant expressed H3 fragments for full-length product in large scale.As a result,nucleosomes with H3K79 modifications as well as photo-reactive group and affinity tag were obtained to investigate potential binding proteins.We believe this method that enhances synthetic accessibility of nucleosome probes will accelerate understanding of the underexplored H3K79 modifications.

正交空间填充设计的最新结果

正交性与空间填充性是计算机试验设计的两个重要性质.本文提出通用的旋转方法用以构造一类新的正交空间填充设计.这类设计既具有正交性,又有理想的空间填充性.此外,本文提出的构造方法简单易行,且生成的设计具有灵活的试验次数和水平数.生成的设计既可以是对称的,也可以是非对称的.相关理论支撑科学严谨.本文构造并给出许多新的具有理想的空间填充性的正交设计.旋转矩阵和差阵在构造中起到重要的作用.

生境差异和人类活动对云南剑川甸南镇小型哺乳动物群落结构和多样性的影响

小型哺乳动物的群落结构可反映当地生境质量,为生态保护提供数据支撑。为了解生境差异和人为干扰对云南省剑川县甸南镇小型哺乳动物群落结构以及多样性的影响,本文于2005年1月至2017年12月,选择4种典型生境(菜园地、耕地、灌丛和住家附近),采用笼捕法对小型哺乳动物展开调查。共布设鼠笼195,612个,捕获小型哺乳动物16,060只,隶属4目7科22种。其中啮齿目捕获到3科15种15,777只,大绒鼠(Eothenomys miletus)和高山姬鼠(Apodemus chevrieri)为甸南镇优势种。不同生境间小型哺乳动物数量差异极显著,数量最多的是灌丛,共5,760只;最少的是住家附近,仅2,160只。菜园地的Shannon-Wiener多样性指数最高(1.26),住家附近最低(1.08)。菜园地和耕地的物种相似性系数最高,为0.94。本研究结果表明,小型哺乳动物的群落结构和多样性受生境差异和人类活动干扰影响:植物资源少、人类活动干扰程度高的生境中多样性指数低;环境条件好、人类活动干扰适度的生境中多样性指数较高;食物资源较少、干扰较少的生境中(如灌丛)多样性指数略低。

A new rotation method for constructing orthogonal Latin hypercube designs

Latin hypercube designs(LHDs)are very popular in designing computer experiments.In addition,orthogonality is a desirable property for LHDs,as it allows the estimates of the main effects in linear models to be uncorrelated with each other,and is a stepping stone to the space-filling property for fitting Gaussian process models.Among the available methods for constructing orthogonal Latin hypercube designs(OLHDs),the rotation method is particularly attractive due to its theoretical elegance as well as its contribution to spacefilling properties in low-dimensional projections.This paper proposes a new rotation method for constructing OLHDs and nearly OLHDs with flexible run sizes that cannot be obtained by existing methods.Furthermore,the resulting OLHDs are improved in terms of the maximin distance criterion and the alias matrices and a new kind of orthogonal designs are constructed.Theoretical properties as well as construction algorithms are provided.

肝泡型包虫病浸润带及其微血管侵犯的研究进展

肝泡型包虫病是一种生物学特性类似恶性肿瘤的寄生虫疾病, 早期无明显临床症状, 多数患者就诊时已出现黄疸、腹水及消化道出血等并发症, 此时病程已属晚期。此外, 由于病灶切除的不彻底导致术后较高的复发率, 给患者的身心健康带来了严重的影响。本文通过对国内外最新研究的总结, 以及对肝泡型包虫病病灶旁"浸润带"内血供、微血管侵犯及血管生长因子表达情况的分析, 深度了解肝泡型包虫病的发生发展过程, 旨在更好地指导临床实践和提高患者的生存质量。