Conformational dynamics as an intrinsic determinant of prion protein misfolding and neurotoxicity

The prion protein(PrP) is the key molecular and pathological mediator of prion diseases,a heterogeneous group of brain disorders with fatal outcomes.Prion diseases are rare but deserve special attention because of their unique familial,sporadic,and transmissible etiologies,all caused by a single agent:misfolded conformations of PrP.

MAUN:Memory-Augmented Deep Unfolding Network for Hyperspectral Image Reconstruction

Spectral compressive imaging has emerged as a powerful technique to collect the 3D spectral information as 2D measurements.The algorithm for restoring the original 3D hyperspectral images(HSIs)from compressive measurements is pivotal in the imaging process.Early approaches painstakingly designed networks to directly map compressive measurements to HSIs,resulting in the lack of interpretability without exploiting the imaging priors.While some recent works have introduced the deep unfolding framework for explainable reconstruction,the performance of these methods is still limited by the weak information transmission between iterative stages.In this paper,we propose a Memory-Augmented deep Unfolding Network,termed MAUN,for explainable and accurate HSI reconstruction.Specifically,MAUN implements a novel CNN scheme to facilitate a better extrapolation step of the fast iterative shrinkage-thresholding algorithm,introducing an extra momentum incorporation step for each iteration to alleviate the information loss.Moreover,to exploit the high correlation of intermediate images from neighboring iterations,we customize a cross-stage transformer(CSFormer)as the deep denoiser to simultaneously capture self-similarity from both in-stage and cross-stage features,which is the first attempt to model the long-distance dependencies between iteration stages.Extensive experiments demonstrate that the proposed MAUN is superior to other state-of-the-art methods both visually and metrically.Our code is publicly available at https://github.com/HuQ1an/MAUN.

Mutation in a non-force-bearing region of protein L influences force-dependent unfolding behavior

Single-molecule magnetic tweezers(MTs) have revealed multiple transition barriers along the unfolding pathway of several two-state proteins, such as GB1 and Csp. In this study, we utilized MTs to measure the force-dependent folding and unfolding rates of both protein L(PLWT) and its Y47W mutant(PLY47W) where the mutation point is not at the force-bearing β-strands. The measurements were conducted within a force range of 3–120 pN. Notably, the unfolding rates of both PLWT and PWY47W exhibit distinct force sensitivities below 50 pN and above 60 pN, implying a two-barrier free energy landscape. Both PLWT and PLY47W share the same force-dependent folding rate and the same transition barriers,but the unfolding rate of PLY47W is faster than that of PLWT. Our finding demonstrates that the residue outside of the force-bearing region will also affect the force-induced unfolding dynamics.

Petrogenesis and Tectonic Implications of the Early Triassic Nianzi Adakitic Granite Unit in the Yanshan Fold and Thrust Belt:New Constraints from U-Pb Geochronology and Sr-Nd-Hf Isotopes

The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.

Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

Protective benefit of folded linear HDPE board sand fences along the Golmud-Korla Railway,China:Field observation and wind tunnel study

The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal protection.This study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand fences.The results suggest that the airflow around the fence creates clear zoning characteristics.The deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the BSF.At different wind speeds,the airflow at 2 and 5 h on the DSF is not disturbed.The WSP(wind speed profile)presents a logarithmic distribution.The airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic law.However,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic distribution.Meanwhile,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field tests.The overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test results.This study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.

Wideband spectrum sensing using step-sampling based on the multipath nyquist folding receiver

Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing,which is subject to the complexity of processing the modulated outputs.In this case,a multipath NYFR architecture with a step-sampling rate for the different paths is proposed.The different numbers of digital channels for each path are designed based on the Chinese remainder theorem(CRT).Then,the detectable frequency range is divided into multiple frequency grids,and the Nyquist zone(NZ) of the input can be obtained by sensing these grids.Thus,high-precision parameter estimation is performed by utilizing the NYFR characteristics.Compared with the existing methods,the scheme proposed in this paper overcomes the challenge of NZ estimation,information damage,many computations,low accuracy,and high false alarm probability.Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper.

Global trends of tropopause folds in recent decades

对流层顶折卷是平流层-对流层物质交换的主要机制.本研究采用三维标记方法,利用1979-2020年间的ERA5再分析数据,分析了对流层顶折卷的时空变化特征及机理.研究结果表明,全球对流层顶折卷的多年变化趋势存在明显的季节性和区域性差异.总体上,对流层顶折卷呈增加趋势,其中北半球的春季,夏季和冬季,对流层顶折卷主要沿副热带急流区呈现明显增加的趋势.进一步分析表明,对流层顶折卷发生频率的增加与大气斜压性增大导致的锋生增强有关,而经向位温梯度的增大使得次级环流增强,也可能促进了对流层顶折卷活动的增多.

Deep learning-based LPI radar signals analysis and identification using a Nyquist Folding Receiver architecture

Nyquist Folding Receiver(NYFR)is a perceptron structure that realizes a low probability of intercept(LPI)signal analog to information.Aiming at the problem of LPI radar signal receiving,the time domain,frequency domain,and time-frequency domain problems of signals intercepted by NYFR structure are studied.Combined with the time-frequency analysis(TFA)method,a radar recognition scheme based on deep learning(DL)is introduced,which can reliably classify common LPI radar signals.First,the structure of NYFR and its characteristics in the time domain,frequency domain,and time and frequency domain are analyzed.Then,the received signal is then converted into a time-frequency image(TFI).Finally,four kinds of DL algorithms are used to classify LPI radar signals.Simulation results demonstrate the correctness of the NYFR structure,and the effectiveness of the proposed recognition method is verified by comparison experiments.

Effect of chaperone–client interaction strength on Hsp70-mediated protein folding

Protein folding in crowding cellular environment often relies on the assistance of various chaperones. Hsp70 is one of the most ubiquitous chaperones in cells. Previous studies showed that the chaperone–client interactions at the open state tend to remodel the protein folding energy landscape and direct the protein folding as a foldase. In this work, we further investigate how the chaperone–client interaction strength modulates the foldase function of Hsp70 by using molecular simulations. The results showed that the time of substrate folding(including the whole folding step and substrate release step) has a non-monotonic dependence on the interaction strength. With the increasing of the chaperone–client interaction strength, the folding time decreases first, and then increases. More detailed analysis showed that when the chaperone–client interaction is too strong, even small number of chaperones–client contacts can maintain the substrate bound with the chaperone. The sampling of the transient chaperones–client complex with sparse inter-molecule contacts makes the client protein have chance to access the misfolded state even it is bound with chaperone. The current results suggest that the interaction strength is an important factor controlling the Hsp70 chaperoning function.

新生代晚期挤压作用下活动背斜区的构造变形特征及其地震地质灾害效应

活动背斜是第四纪晚期以来在活动挤压构造区域内吸收地壳缩短变形的主要地质构造之一,其是在挤压背景下形成的一个复杂的构造系统,由多种活动构造变形组成。发生在挤压构造区的大地震可以使褶皱相关断层、褶皱陡坎、翼部地形倾斜和地质体缩短等发生同震破裂或地面倾斜,进而引发严重的地震地质灾害,从理论研究和工程抗震两方面均需重视。因此,文章立足现有的逆断层相关褶皱、褶皱侧向扩展等理论,通过典型的主逆冲断层、反冲断层、弯矩断层、弯滑断层、共轭剪切断层和褶皱陡坎等实例,探讨了与褶皱相关的同震活动构造变形对建筑物的影响和破坏作用。研究认为,在强震导致的活动背斜地壳缩短、垂向隆升和侧向扩展过程中,背斜两翼和倾伏端的地面掀斜对重大工程建筑的安全运行构成威胁;同时,区域地壳缩短引发的弯曲变形给跨越活动背斜的重大线状工程造成的潜在地震危险和诱发的地质灾害值得关注。

Paradoxical vocal fold motion masquerading as post-anesthetic respiratory distress:A case report

BACKGROUND Functional vocal cord disorders can be a differential diagnosis for postoperative upper airway obstruction requiring urgent intervention.However,this may be unfamiliar to anesthesiologists who would favor inappropriate airway intervention and increased morbidity.CASE SUMMARY A 61-year-old woman underwent cervical laminectomy,followed by laparoscopic cholecystectomy 10 mo later.Despite adequate reversal of neuromuscular blockade,the patient experienced repetitive respiratory difficulty with inspiratory stridor after extubation.After the second operation,the patient was diagnosed with paradoxical vocal fold motion(PVFM)by an otolaryngologist based on the clinical features and fiberoptic bronchoscopy results,and the patient was successfully treated.CONCLUSION PVFM should be considered a differential diagnosis if a patient presents with stridor after general anesthesia.

Optical coherence tomography enhanced depth imaging of chorioretinal folds in patients with orbital tumors

AIM:To characterize spectral-domain optical coherence tomography(SD-OCT)features of chorioretinal folds in orbital mass imaged using enhanced depth imaging(EDI).METHODS:Prospective observational case-control study was conducted in 20 eyes of 20 patients,the uninvolved eye served as a control.All the patients underwent clinical fundus photography,computed tomography,EDI SDOCT imaging before and after surgery.Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5;the remaining patients underwent tumor excision.Patients were followed 1 to 14mo following surgery(average follow up,5.8mo).RESULTS:Visual acuity prior to surgery ranged from 20/20 to 20/200.Following surgery,5 patients’visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10(range 4 to 26 letters).Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery.Following surgical excision,photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients.CONCLUSION:Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis.Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.

主动脉穿刺型轴流血泵折边结构叶轮的数值模拟及溶血分析

为解决血泵因叶顶间隙泄漏而造成溶血和血栓等问题,引入了一种折边不等间距叶轮,采用计算流体力学(computational fluid dynamics, CFD)进行内部流场的数值模拟,并与非折边不等间距叶轮及折边等间距叶轮进行对比分析,研究了它们的内流场动力学特性和血液相容性.结果表明:折边叶片结构血泵避免了叶顶间隙泄漏流的产生,同时折边不等间距叶轮减少了叶轮入口和出口处的回流和涡流,流道内整体切应力低于其他2种叶轮;3种叶轮的溶血指数HI均满足血泵的溶血设计指标,其中,折边不等间距叶轮血泵壁面切应力在0~150 Pa的占比达96.84%,曝光时间相对集中且满足人工血泵设计要求,溶血指数较非折边不等间距叶轮血泵下降了3.50%,较折边等间距叶轮血泵下降了12.50%,溶血性能最优.提出的折边不等间距叶轮血泵可有效降低红细胞破损概率,减少溶血和血栓的发生,可为轴流血泵的结构设计和优化提供一定参考.

一种小型火工机构的输出计算及其验证

针对某折叠翼展开机构的小型化难题,研究了一种小型火工机构。利用内弹道理论建立了该火工机构的输出理论模型,通过理论模型计算和优化了机构参数,并用有限元法校验了计算结果。测试结果表明:该原型机具备了小型特点,其输出角度达到了128.5°。在逆风和顺风负载下,该火工机构的工作时间均小于200 ms,其最大角速度不大于3 000 (°)/s,试验数据证实该火工机构具备缓冲作用,理论计算结果和试验数据基本一致。研究成果可作为薄型折叠翼的一种设计方法,为薄型折叠翼的工程应用奠定技术基础。

V型折叠颏下皮瓣修复口腔缺损的临床应用

目的:口腔中小型缺损修复一直是一个难题,游离皮瓣和远位带蒂组织瓣难以满足临床需求,传统颏下皮瓣存在供区损伤风险。本研究旨在探讨V型折叠颏下皮瓣修复口腔中小型缺损的疗效。方法:回顾性分析2019年3月至2022年12月中南大学湘雅三医院口腔科收治的28例口腔黏膜病变患者的临床资料。根据颏下皮瓣手术方式的不同将患者分为V型折叠组(17例)和传统组(11例),V型折叠组采用V型折叠颏下皮瓣进行术后软组织修复,传统组采用传统颏下皮瓣进行修复,患者术后随访6~48个月。比较2组皮瓣存活情况、皮瓣修复时间以及皮瓣修复效果。结果:2组皮瓣存活率、皮瓣大小、制瓣时间、修复手术时间和术后住院时间差异均无统计学意义(均P>0.05)。术后6个月,V型折叠组无抬头困难和下唇外翻,无皮肤“猫耳”畸形,疤痕隐藏于下颌骨下缘处,创面美观度、功能评分均明显高于传统组(均P<0.05)。结论:V型折叠颏下皮瓣具有设计灵活、制备简单、血供可靠、保护供区等优点,可以有效维持颏部美观和避免功能障碍。

多闭环厚板折展蜂窝机构的几何设计与性能分析

基于厚板折纸理论设计出一种单闭环空间折展机构,并用螺旋理论对机构的自由度进行了分析。引入Myard类型约束和Sarrus类型约束,提出将机构自由度降低为1的2种方法,对应得到M型和S型折展蜂窝单元。将2种折展蜂窝单元的运动特征与平面镶嵌原理相结合,构造出M型和S型折展蜂窝机构。研究了设计参数对机构折展率的影响规律,并以提高折展率为目标对机构的结构进行了优化。研究结果表明,M型折展蜂窝机构完全展开后可形成单侧平整的表面;S型折展蜂窝机构的折展率更大。

基于石墨烯片的频率可调太赫兹天线

本文设计了一种基于石墨烯片的频率可调太赫兹天线,采用了折叠缝隙结构并使用共面波导馈电方式,以更好地实现阻抗匹配.通过调控在缝隙之间添加的4个石墨烯片的电导率,改变缝隙天线的等效长度,使天线在两种不同工作模式下的谐振频率分别为230.5 GHz和270.5 GHz.除此之外,在天线下方加载了方形封闭谐振环(Closed-Ring Resonator,CRR)构成的超表面,并使其谐振频率与天线的谐振频率匹配,将z轴负方向的辐射进行反射,使天线在两种工作模式下的增益提高至5.41 dBi和7.63 dBi,与无反射结构时相比分别增长2.48 dBi和3.55 dBi.

体外丝线牵拉辅助两孔腹腔镜内环缝合在治疗内环口皱褶冗厚斜疝中的应用

目的探讨体外丝线牵拉辅助两孔腹腔镜内环缝扎治疗内环皱褶冗厚斜疝的安全性、可行性。方法2019年10月~2023年2月,322例斜疝患儿接受两孔法腹腔镜内环缝扎,其中186例(292侧)内环皱褶冗厚患儿采用体外丝线牵拉法辅助。在腹腔镜监视下,针持持针经内环口外下缘入腹膜,于腹膜后间隙走行至精索血管外侧缘出针;于精索血管外侧缘进针,体外轻轻牵拉线尾,腹腔镜下见进针点附近后腹膜间隙增大,缝针顺势在后腹膜间隙跨越精索血管表面。相同方法牵拉和展开折叠在输精管-髂外血管间隙的腹膜皱褶,增大后腹膜间隙,缝针继续在后腹膜间隙贴近髂血管表面跨越Doom三角区冗厚的腹膜组织。相同方法于腹膜外间隙跨越输精管表面。继续直视下缝合内环口内侧壁和上壁腹膜组织,于最初进针处出针和打结,闭合内环口。结果292侧体外丝线牵拉冗厚腹膜后,缝针能顺利跨越精索血管、Doom三角区以及输精管表面。80例单侧手术时间(18.5±3.2)min,106例双侧手术时间(32.6±5.3)min。均无术中并发症发生,均在术后6 h内出院。122例术后随访3~18个月(平均8.5月),未出现切口感染、医源性隐睾或睾丸萎缩等并发症,无复发疝、鞘膜积液。结论对于内环皱褶冗厚的儿童斜疝,体外丝线牵拉法可有效展开冗厚的后腹膜,降低两孔法腹腔镜内环口缝扎时缝针跨越精索血管、Doom三角区以及输精管表面的难度,具有安全性、可行性。

仿生六足折纸机器人结构设计与运动分析

针对现有折纸机器人组成结构单一,运动不够灵活的问题,将折纸结构与多足机器人设计相结合,耦合三浦折纸和六折痕折纸,提出新型的仿螃蟹六足折纸机器人设计方案,扩展了折纸机器人的运动构型,提升了折纸机器人的运动灵活性.在面对称假设下,该机器人单足具有2个自由度,此时将机器人腿部顶点等效为关节,轴线折痕等效为连杆,建立机器人腿部的平面连杆等效模型,并以折面夹角为运动变量,通过仿真计算得出机器人足端的理论运动范围.利用楔形面板技术对折面增厚并避免相邻折面发生物理干涉,建模得到折纸仿螃蟹六足机器人的三维模型.基于平面连杆的等效模型,分析折面夹角与足端运动之间的联系,设计确定机器人的足端运动轨迹与运动步态.利用3D打印技术设计并制作折纸仿生六足机器人试验样机,基于STM32单片机控制实现了机器人三横向角步态运动.结果表明,该折纸仿生机器人可以实现平面构型到仿螃蟹构型的转换,在6条腿的协同运动下,机器人可以平稳地左右横向移动.