A Novel Method to Enhance the Inversion Speed and Precision of the NMR T_(2) Spectrum by the TSVD Based Linearized Bregman Iteration

The low-field nuclear magnetic resonance(NMR)technique has been used to probe the pore size distribution and the fluid composition in geophysical prospecting and related fields.However,the speed and accuracy of the existing numerical inversion methods are still challenging due to the ill-posed nature of the first kind Fredholm integral equation and the contamination of the noises.This paper proposes a novel inversion algorithmto accelerate the convergence and enhance the precision using empirical truncated singular value decompositions(TSVD)and the linearized Bregman iteration.The L1 penalty term is applied to construct the objective function,and then the linearized Bregman iteration is utilized to obtain fast convergence.To reduce the complexity of the computation,empirical TSVD is proposed to compress the kernel matrix and determine the appropriate truncated position.This novel inversion method is validated using numerical simulations.The results indicate that the proposed novel method is significantly efficient and can achieve quick and effective data solutions with low signal-to-noise ratios.

Kinematic Calibration of a Six-Legged Walking Machine Tool

This paper presents the kinematic calibration of a novel six-legged walking machine tool comprising a six-legged mobile robot integrated with a parallel manipulator on the body.Each leg of the robot is a 2-universal-prismatic-spherical(UPS)and UP parallel mechanism,and the manipulator is a 6-PSU parallel mechanism.The error models of both subsystems are derived according to their inverse kinematics.The objective function for each kinematic limb is formulated as the inverse kinematic residual,i.e.,the deviation between the actual and computed joint coordinates.The hip center of each leg is first identified via sphere fitting,and the other kinematic parameters are identified by solving the objective function for each limb individually using the least-squares method.Thus,the kinematic parameters are partially decoupled,and the complexities of the error models are reduced.A calibration method is proposed for the legged robot to overcome the lack of a fixed base on the ground.A calibration experiment is conducted to validate the proposed method,where a laser tracker is used as the measurement equipment.The kinematic parameters of the entire robot are identified,and the motion accuracy of each leg and that of the manipulator are significantly improved after calibration.Validation experiments are performed to evaluate the positioning and trajectory errors of the six-legged walking machine tool.The results indicate that the kinematic calibration of the legs and manipulator improves not only the motion accuracy of each individual subsystem but also the cooperative motion accuracy among the subsystems.

Construction of a cement-rebar nanoarchitecture for a solution-processed and flexible film of a Bi_(2)Te_(3)/CNT hybrid toward low thermal conductivity and high thermoelectric performance

Solution processability and flexibility still remain major challenges for many thermoelectric(TE)materials,including bismuth telluride(Bi_(2)Te_(3)),a typical and commercially available TE material.Here,we report a new solutionprocessed method to prepare a flexible film of a Bi_(2)Te_(3)/single-walled carbon nanotube(SWCNT)hybrid,where the dissolved Bi_(2)Te_(3) ion precursors are mixed with dispersed SWCNTs in solution and recrystallized on the SWCNT surfaces to form a“cement-rebar”-like architecture.The hybrid film shows an n-type characteristic,with a stable Seebeck coefficient of^(−1)00.00±1.69μVK^(−1) in air.Furthermore,an extremely low in-plane thermal conductivity of∼0.33Wm^(−1) K^(−1) is achieved at 300 K,and the figure of merit(ZT)reaches 0.47±0.02.In addition,the TE performance is independent of mechanical bending.The unique“cement-rebar”-like architecture is believed to be responsible for the excellent TE performances and the high flexibility.The results provide a new avenue for the fabrication of solution-processable and flexible TE hybrid films and will speed up the applications of flexible electronics and energy conversion.

Comparative Analysis and Comprehensive Evaluation of Fishery Water Quality of the Major Lakes in Jiangsu Province Based on Long-term Monitoring Data

The variance analysis of fishery water quality data of five lakes from 2001 to 2011( except 2004) was performed to compare the difference of the monitoring indicators among the five above-mentioned lakes in Jiangsu Province. And TOPSIS method was employed to give comprehensive comparison of water quality of the five lakes. The results indicated that the difference of 14 major water quality indicators was very significant among lakes except copper. In addition,transparency,total nitrogen,total phosphorus had very significant difference among stations for each lake; p H,chemical oxygen demand,oil,total phosphorus,lead,cadmium,mercury had significant or very significant difference among years for each station. The TOPSIS results showed that the fishery water quality of Gaobaoshaobo Lake was the best,and Luoma Lake was just second to it,followed by Hongze Lake,Taihu Lake and Gehu Lake. In combination with the geographic position of each lake,it showed that fishery water quality of the five investigated lakes was basically increasingly better from the south to the north in Jiangsu Province,and the trend revealed high association with the developed industrial economy.

Downregulation of cardiac PIASy inhibits Cx43 SUMOylation and ameliorates ventricular arrhythmias in a rat model of myocardial ischemia/reperfusion injury

Background:Dysfunction of the gap junction channel protein connexin 43(Cx43)contributes to myocardial ischemia/reperfusion(I/R)-induced ventricular arrhythmias.Cx43 can be regulated by small ubiquitin-like modifier(SUMO)modification.Protein inhibitor of activated STAT Y(PIASy)is an E3 SUMO ligase for its target proteins.However,whether Cx43 is a target protein of PIASy and whether Cx43 SUMOylation plays a role in I/R-induced arrhythmias are largely unknown.Methods:Male Sprague-Dawley rats were infected with PIASy short hairpin ribonucleic acid(shRNA)using recombinant adeno-associated virus subtype 9(rAAV9).Two weeks later,the rats were subjected to 45 min of left coronary artery occlusion followed by 2 h reperfusion.Electrocardiogram was recorded to assess arrhythmias.Rat ventricular tissues were collected for molecular biological measurements.Results:Following 45 min of ischemia,QRS duration and QTc intervals statistically significantly increased,but these values decreased after transfecting PIASy shRNA.PIASy downregulation ameliorated ventricular arrhythmias induced by myocardial I/R,as evidenced by the decreased incidence of ventricular tachycardia and ventricular fibrillation,and reduced arrythmia score.In addition,myocardial I/R statistically significantly induced PIASy expression and Cx43 SUMOylation,accompanied by reduced Cx43 phosphorylation and plakophilin 2(PKP2)expression.Moreover,PIASy downregulation remarkably reduced Cx43 SUMOylation,accompanied by increased Cx43 phosphorylation and PKP2 expression after I/R.Conclusion:PIASy downregulation inhibited Cx43 SUMOylation and increased PKP2 expression,thereby improving ventricular arrhythmias in ischemic/reperfused rats heart.

Synthesis and application of single-atom catalysts in sulfur cathode for high-performance lithium–sulfur batteries

Lithium–sulfur(Li-S)batteries are regarded as one of the most promising energy storage devices because of their low cost,high energy density,and environmental friendliness.However,Li-S batteries suffer from sluggish reaction kinetics and serious“shuttle effect”of lithium polysulfides(LiPSs),which causes rapid decay of battery capacity and prevent their practical application.To address these problems,introducing single-atom catalysts(SACs)is an effective method to improve the electrochemical performance of Li-S batteries,due to their high catalytic efficiency and definite active sites for LiPSs.In this paper,we summarized the latest developments in enhancing the electrochemical performance of cathode for Li-S batteries through introducing different SACs.Furthermore,we briefly introduced the catalytic mechanism of SACs and discussed the strategies of synthesizing SACs,including the spatial confinement strategy and the coordination design strategy.Finally,the challenges and prospects in this field are proposed.We believe that this review would help to design and fabricate high-performance Li-S batteries via introducing SACs and boost their practical application.

首诊眼科的儿童颅内肿瘤三例

很多颅脑肿瘤患者发病初期可表现为神经眼科症状,患者常首诊于眼科,典型的初期症状是进行性视力下降,伴或不伴视神经萎缩、视野缺损和眼外肌麻痹等[1]。当肿瘤未累及视路或累及初期,视功能损害常不明显,患者也可同时伴有眼部疾病,遮掩了肿瘤引起的视功能损害;儿童患者往往因主诉表达不清,视野检查难以配合等更容易误诊、漏诊[2]。笔者回顾近期3例首诊于我院眼科而最终被诊断为颅脑肿瘤患儿临床资料,现报告如下。

笔尖训练与双眼视觉训练治疗间歇性外斜视术后欠矫的疗效对比

目的:比较笔尖训练法和双眼视觉训练法治疗间歇性外斜视患者术后轻度欠矫的疗效。方法:前瞻性队列研究。纳入在南京医科大学附属儿童医院眼科接受间歇性外斜视手术治疗并于2015年6月至2016年6月发生术后轻度欠矫(-8^△^-15^△)的患者54例。将患者分为笔尖训练组和双眼视觉训练组。笔尖训练为将笔尖由远移近到鼻根至出现复视后再退回,患者反复训练,20个周期为1组,连续做3组,共约15min,每天2次,每周训练5d,持续6个月;双眼视觉训练组患者进行每周1次,每次60min的医院内训练,以及每周5次,每次15min的家庭训练,持续6个月。所有患者均于训练前,训练1个月、3个月和6个月时接受看远斜视度、看近斜视度和看远立体视检查。数据采用独立样本t检验、重复测量两因素方差分析、卡方检验进行分析。结果:54例患者中,26例进行笔尖训练,28例进行双眼视觉训练。训练前笔尖训练组和双眼视觉训练组的看远、看近斜视度差异无统计学意义;训练3个月时,笔尖训练组看远、看近斜视度均大于双眼视觉训练组,差异有统计学意义(t=3.44,P<0.001;t=2.55,P=0.01)。双眼视觉训练组训练1个月和3个月时看远斜视度差值、看近斜视度差值均大于笔尖训练组,差异有统计学意义(t=-3.17,P=0.003;t=2.32,P=0.02)。训练1个月、3个月时,2组看远立体视差异无统计学意义;训练6个月时,双眼视觉训练组看远立体视优于笔尖训练组,差异有统计学意义(t=9.33,P<0.001),训练6个月时,双眼视觉训练组正常立体视获得率高于笔尖训练组,差异有统计学意义(χ^2=5.02,P=0.03)。结论:笔尖训练和双眼视觉训练均能降低间歇性外斜视术后欠矫患者斜视度,效果一致,但双眼视觉训练对欠矫患儿立体视功能的恢复优于笔尖训练。

Progress of Jinping Underground laboratory for Nuclear Astrophysics(JUNA)

Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of^(25)Mg(p,γ)^(26)Al,^(19)F(p,α)^(16)O,^(13)C(α,n)^(16)O and ^(12)C(α,γ)^(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.

AN INTEGRATED COUPLING ELEMENT FOR VEHICLE-RAIL-BRIDGE INTERACTION SYSTEM WITH A NON-UNIFORM CONTINUOUS BRIDGE

An integrated coupling element considering wheel-rail interface for analyzing the dynamic responses of vehicle-rail-bridge interaction system with a non-uniform continuous bridge is presented. The governing equations of the interaction system are established first, and the solution procedure and assembly method of the coupling element are demonstrated. Finally, the accuracy, efficiency and function of the integrated coupling element are tested using two numerical examples. The influences of different combinations of rail and bridge element length in the coupling element on the solution are investigated, and the effects of different rail irregularities on the dynamic responses are discussed.

Carbon dots confined in 3D polymer network: Producing robust room temperature phosphorescence with tunable lifetimes

Room temperature phosphorescence(RTP) is important in both organic electronics and encryption. Despite rapid advances, a universal approach to robust and tunable RTP materials based on amorphous polymers remains a formidable challenge. Here, we present a strategy that uses three-dimensional(3 D)confinement of carbon dots in a polymer network to achieve ultra-long lifetime phosphorescence. The RTP of the as-obtained materials was not quenched in different polar organic solvents and the lifetime of the RTP was easily tuned by adjusting the amount of crosslinking or varying the drying temperature of the 3 D molecular network. As a demonstration of potential application, as-obtained RTP materials were successfully used to prepare RTP fibres for flexible textiles. As well as bringing to light a fundamental principle for the construction of polymer materials with RTP, we have endowed traditional carbon dots and polymers with fresh features that will expand potential applications.

Host–Guest Interaction Driven Peptide Assembly into Photoresponsive Two-Dimensional Nanosheets with Switchable Antibacterial Activity

Selectively controlling the bioactivity of antimicrobial peptides is not only a fascinating scientific challenge but also a necessity in localized antibacterial therapy.Here,a smart antimicrobial system has been fabricated via host–guest driven dynamic selfassembly between a branched cyclodextrin and cationic linear peptides appended with azobenzene side chains.The self-assembly structure of the host–guest system could be controlled reversibly through the photoresponsive isomerization of azobenzene moieties.

Microstructure and mechanical properties of Mg-14Li-1Al-0.3La alloys produced by two-pass extrusion

The microstructure of as-cast and extruded Mg-14 Li-1 Al-（0, 0.3） La alloys was examined with XRD,OM, SEM, and EDS. The mechanical properties of the extruded specimens with and without La were compared. The results show that La addition has an obvious effect on the microstructure of the as-cast LA141 alloy by reducing the average grain size from 600 to 220 μm. β-Li and LiMgAl2 phases are observed in both alloys, and long-rod-shaped Al2 La phase is also observed in the La containing alloy. After extrusion, Al2 La phases are short-rod-shaped and distribute evenly in the alloy. LAl41-0.3 La alloy has higher elongation（34%）, which is attributed to refined microstructure and weak texture due to shortrod-like Al2 La phase.

比较阿托品和复方托吡卡胺对学龄期儿童散光的影响

目的:对6~12岁儿童使用阿托品和复方托吡卡胺麻痹睫状肌前后的散光变化进行矢量分析,探讨不同睫状肌麻痹剂对学龄期儿童散光的影响。方法:回顾性病例对照研究。收集2019年1月至2020年9月于南京医科大学附属儿童医院眼科门诊进行睫状肌麻痹验光的6~12岁儿童1262例(1262眼),按使用不同睫状肌麻痹剂分为阿托品组(530眼)和复方托吡卡胺组(732眼),均选取右眼作为研究对象。采用TOPCON KR 800型全自动电脑验光仪对所有儿童进行睫状肌麻痹前后电脑验光检查,记录球镜度、柱镜度和轴向。通过Thibos矢量分析方法将散光分解为J0和J45。睫状肌麻痹前后散光各矢量成分的差异比较采用t检验,睫状肌麻痹前后J0和J45的相关性采用Spearman相关分析,一致性采用Bland-Altman图描述。结果:复方托吡卡胺组睫状肌麻痹后J0成分增加0.04±0.13(t=8.34,P<0.001)。进一步按散光程度和SE高低分组,阿托品组睫状肌麻痹前后J0和J45差异均无统计学意义;复方托吡卡胺组J0差异在各组均有统计学意义(均P<0.001),J45仅在高度散光组及近视组差异有统计学意义(t=-2.18,P=0.031;t=-2.67,P=0.008)。Spearman相关分析发现2组睫状肌麻痹前后J0和J45相关性高,Bland-Altman分析显示2组睫状肌麻痹前后J0和J45一致性均较好。结论:与阿托品相比,滴用复方托吡卡胺进行睫状肌麻痹后散光变化显著,特别是对近视或高度散光的学龄期儿童。