Finite-Time Stabilization for Constrained Discrete-time Systems by Using Model Predictive Control

In this paper, a model predictive control(MPC)framework is proposed for finite-time stabilization of linear and nonlinear discrete-time systems subject to state and control constraints. The proposed MPC framework guarantees the finite-time convergence property by assigning the control horizon equal to the dimension of the overall system, and only penalizing the terminal cost in the optimization, where the stage costs are not penalized explicitly. A terminal inequality constraint is added to guarantee the feasibility and stability of the closed-loop system.Initial feasibility can be improved via augmentation. The finite-time convergence of the proposed MPC is proved theoretically,and is supported by simulation examples.

Highly Sensitive Detection of Strontium Ions Using Metal-Organic Frameworks Functionalized Solid-state Nanochannels

Strontium-90,a highly radioactive isotope,accumulates within the food chain and skeletal structure,posing significant risks to human health.There is a critical need for a sensitive detection strategy for Strontium-90 in complex environmental samples.Here,solid-state nanochannels,modified with metal-organic frameworks(MOF)and specific aptamers,were engineered for highly sensitive detection of strontium ion(Sr^(2+)).The synergistic effect between the reduced effective diameter of the nanochannels due to MOF and the specific binding of Sr^(2+) by aptamers amplifies the difference in ionic current signals,enhancing detection sensitivity significantly.The MOF-modified nanochannels exhibit highly sensitive detection of Sr^(2+),with a limit of detection(LOD)being 0.03 nmol·L^(-1),whereas the LOD for anodized aluminum oxide(AAO)without the modified MOF nanosheets is only 1000 nmol·L^(-1).These findings indicate that the LOD of Sr^(2+) detected by the MOF-modified nanochannels is approximately 33,000 times higher than that by the nanochannels without MOF modification.Additionally,the highly reliable detection of Sr^(2+) in various water samples was achieved,with a recovery rate ranging from 94.00%to 118.70%.This study provides valuable insights into the rapidly advancing field of advanced nanochannel-based sensors and their diverse applications for analyzing complex samples,including environmental contaminant detection,food analysis,medical diagnostics,and more.

Automatic Scallion Seedling Feeding Mechanism with an Asymmetrical High-order Transmission Gear Train

The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.

The relationship between soil,climate and forest development in the mid-mountain zone of the Sangong River watershed in the northern Tianshan Mountains,China

The mountainous forests in arid regions, being sensitive to climate change, are one of the key research topics related to the mechanism of interaction between climate and the terrestrial ecosystem. In this study, the spatial distribution of a mid-mountain forest and its environmental factors were investigated by using a combination of remote sensing technology, field survey, climate indices and soil nutrient analysis in the Sangong River watershed of the northern Tianshan Mountains. The forest （Picea schrenkiana） was distributed between 1,510 and 2,720 m asl. Tree height and diameter at breast height （DBH） exhibited a bi-modal pattern with increasing elevation, and rested at 2,450 and 2,250 m asl, respectively. The two maxima of DBH appeared at 2,000 and 2,550 m asl, and the taller trees were observed at 2,100 and 2,600 m asl. For the annual mean temperature, the difference was approximately 5.8℃ between the lowest and the highest limits of the forest, and the average decreasing rates per hundred meters were 0.4g℃ and 0.55℃ with increasing altitude between 1,500 and 2,000 m asl and above 2,000 m asl, respec- tively. The annual precipitation in the forest zone first increased and then decreased with the increase of altitude, and the maximum value was at 2,000 m asl. For per hundred meters, the annual precipitation increased with the rate of 31 mm between 1,500 and 2,000 m asl and decreased by 7.8 mm above 2,000 m asl. The SOM, TN and TP were high between 2,000 and 2,700 m asl and low at the lower and upper forest limits. The minimum CaCO3 con- centration, pH value and EC coincided with the maximum precipitation belt at 2,000 m asl. The SOM, TN and TP were high in the topsoil （0-10 cm） and differed significantly from the values observed in the deep soil layers （〉10 cm）. The soil nutrients exhibited spatial heterogeneity and higher aggregation in the topsoil. In conclusion, soil and climate are closely related to each other, working synergistically to determine the development and spatial distribution of the mid-mountain forest in the study area. The order of the importance of environmental factors to forest development in this study is as follows： soil nutrients〉precipitation〉elevation〉temperature.

基于足底压力和卷积长短期记忆神经网络的前交叉韧带断裂智能辅助诊断

提出一种基于卷积长短期记忆神经网络的深度学习模型PressureConvLSTM,用来提取行走过程中足底压力的空间特征和时序特征,并进行步态分类。通过对前交叉韧带断裂患者的足底压力数据分析,实现智能辅助诊断。结合临床数据的实验结果表明,PressureConvLSTM模型对前交叉韧带断裂的辅助诊断,能够达到95%的预测准确度;与卷积神经网络等其他模型相比,准确度得到大幅度提升。

Thrombotic pulmonary embolism of inferior vena cava during caesarean section:A case report and review of the literature

BACKGROUND Thrombotic pulmonary embolism(TPE)is one of the most critical diseases in obstetrics but is rarely reported in caesarean section(CS)because TPE patients in CS have a high risk of death and are difficult to diagnose.This case report of TPE during CS was recorded by transthoracic echocardiography(TTE)and can provide a reference for the differential diagnosis of critical illnesses in CS.CASE SUMMARY A 37-year-old pregnant woman with rheumatic heart disease(RHD),gravida 5 and para 1(G5P1),presented for emergency CS at 33 wk and 3 d of gestation under general anesthesia because of acute heart failure,pulmonary hypertension and arrhythmia.After placental removal during CS,TTE revealed a nascent thrombus in the inferior vena cava(IVC)that elongated,detached and fragmented leading to acute thromboembolic events and acute TPE.This report presents the whole process and details of TPE during CS and successful rescue without any sequelae in the patient.This case gives us new ideas for the diagnosis of death or cardiovascular accidents during CS in pregnant women with heart disease and the detailed presentation of the rapid development of TPE may also elucidate new ideas for treatment.This case also highlighted the importance of prophylactic anticoagulation in the management of heart disease during pregnancy.CONCLUSION Pregnancy with heart failure could trigger inferior vena cava(IVC)-origin TPE during CS.Detection and timely treatment can avoid serious consequences.

Effect of Hf^(4+) doping on structure and enhancement of upconversion luminescence in Yb:Tm:LiNbO_3 crystals

A series of Yb：Tm：LiNbO_3 crystals doped with x mol% Hf^（4＋）ions（x = 2, 4, and 6） were grown by the Czochralski method. The dopant occupancy and defect structure of Hf：Yb：Tm：LiNbO_3 crystals were investigated by x-ray diffraction and infrared transmission spectra. The influence of Hf^（4＋）ions concentration on UV–VIS–NIR absorption spectra of Hf：Yb：Tm：LiNbO_3 crystals was discussed. The upconversion luminescence of Hf：Yb：Tm：LiNbO_3 crystals was obtained under 980 nm excitation. Strong emissions were observed at 475 nm in the blue wavelength range and 651 nm in the red wavelength range. Remarkably, enhancement of the red and blue upconversion luminescence was achieved by tridoping Hf^（4＋）ions.

Phylogenetic Analysis of Legionella Strains and Identification of Serogroups by Lipopolysaccharide-and O-antigen-based PCR Assay

Legionella,a genus of pathogenic Gram-negative bacteria,is widely present in natural water sources and artificial water systems.A total of 65 species and>70 serogroups of Legionella have been characterized[1].Lipopolysaccharide(LPS),the main component of the outer membrane of Legionella,is not only associated with toxicity,but also provides the basis for classification in serotyping[2].

The Normalized Laplacians on Both Two Iterated Constructions Associated with Graph and Their Applications

Given a simple connected graph G, we consider two iterated constructions associated with G: Fk (G) and Rk (G) . In this paper, we completely obtain the normalized Laplacian spectrum of Fk (G) and Rk (G) , with k ≥2, respectively. As applications, we derive the closed-formula of the multiplicative degree-Kirchhoff index, the Kemeny’s constant, and the number of spanning trees of Fk?(G)? , Rk?(G) , r-iterative graph ,Frk?(G)? and r-iterative graph , where k?≥2 and r?≥1 . Our results extend those main results proposed by Pan et al. (2018), and we provide a method to characterize the normalized Laplacian spectrum of iteratively constructed complex graphs.

Shikimic acid accelerates phase change and flowering in Chinese jujube

The juvenile-to-adult phase change with first flowering as the indicator plays a crucial role in the lifecycle of fruit trees. However, the molecular mechanisms underlying phase change in fruit trees remain largely unknown. Shikimic acid (ShA) pathway is a main metabolic pathway closely related to the synthesis of hormones and many important secondary metabolites participating in plant phase change. So,whether ShA regulates phase change in plants is worth clarifying. Here, the distinct morphological characteristics and the underlying mechanisms of phase change in jujube (Ziziphus jujuba Mill.), an important fruit tree native to China with nutritious fruit and outstanding tolerance abiotic stresses, were clarified. A combined transcriptome and metabolome analysis found that ShA is positively involved in jujube(Yuhong’×Xing 16’) phase change. The genes in the upstream of ShA synthesis pathway (ZjDAHPS, ZjDHQS and ZjSDH), the contents of ShA and the downstream secondary metabolites like phenols were significantly upregulated in the phase change period. Further, the treatment of spraying exogenous ShA verified that ShA at a very low concentration (60 mg·L^(-1)) can substantially speed up the phase change and flowering of jujube and other tested plants including Arabidopsis, tomato and wheat. The exogenous ShA (60 mg·L^(-1)) treatment in jujube seedlings could increase the accumulation of endogenous ShA, enhance leaf photosynthesis and the synthesis of phenols especially flavonoids and phenolic acids, and promote the expression of genes (ZjCOs, ZjNFYs and ZjPHYs) involved in flowering pathway. Basing on above results, we put forward a propose for the underlying mechanism of ShA regulating phase change, and a hypothesis that ShA could be considered a phytohormone-like substance because it is endogenous, ubiquitous, movable and highly efficient at very low concentrations. This study highlights the critical role of ShA in plant phase change and its phytohormone-like properties.

葛根素靶向线粒体抑制乳腺癌细胞增殖和侵袭的机制

目的利用网络药理学、分子对接及体外实验验证探讨葛根素对人乳腺癌细胞HCC1806增殖、侵袭和凋亡的作用及机制。方法GEO数据库收集乳腺癌和线粒体疾病数据,GEO2R分析差异性表达基因;韦恩图分析乳腺癌与线粒体数据集的重叠基因;GO和KEGG功能富集分析重叠基因;STRING和Cytoscape分析重叠基因相互作用网络并筛选核心基因;Autodock对接葛根素和核心基因;通过CCK-8、EdU、TUNEL和Transwell实验检测细胞增殖、凋亡和侵袭能力,采用Mito-Tracker实验检测线粒体膜电位,Western blot检测蛋白质表达水平。体内实验通过乳腺癌皮下异种移植和免疫组化分析葛根素的抗肿瘤药效。结果乳腺癌和线粒体疾病共有132个重叠基因,筛选出10个核心差异性表达基因,其中双丝氨酸/苏氨酸和酪氨酸蛋白激酶(DST)在乳腺癌组织中呈低表达。葛根素可结合并上调DST表达,抑制人乳腺癌细胞HCC1806增殖和侵袭,促进细胞凋亡,增加凋亡相关蛋白Cleaved-Caspase 3和Bax表达,下调抗凋亡蛋白Bcl-2的表达,降低线粒体膜电位。体内实验显示葛根素可抑制乳腺癌的生长,上调瘤体组织中DST的表达。结论葛根素抑制乳腺癌细胞增殖及侵袭并促进癌细胞凋亡进而抑制乳腺癌生长。

Wnt4重组蛋白对炎症状态下成骨细胞的影响

目的建立体外炎性环境,对比研究Wnt4重组蛋白在炎症状态下对成骨细胞分化及矿化能力的影响,初步探讨Wnt重组蛋白在炎症状态下调控成骨细胞分化的作用。方法通过酶消法从小鼠颅顶骨中提取成骨细胞,CCK8法检测不同浓度LPS、Wnt4重组蛋白对小鼠成骨细胞增殖分化的影响,设计浓度梯度,根据检测结果确定所需的最适浓度。体外成骨诱导培养,按是否添加LPS、Wnt4重组蛋白分为对照组、LPS组、Wnt4组、LPS+Wnt4组4个组。培养7 d后比较碱性磷酸酶(ALP)活性。培养21 d后应用茜素红染色法比较细胞矿化能力。结果经过分组培养7 d后,与LPS组比较,LPS+Wnt4组ALP活性明显升高,P<0.05。第21天的茜素红染色结果表明,LPS+Wnt4组矿化能力高于LPS组,P<0.05。结论Wnt4重组蛋白(0.05μg/mL)对炎症状态下的成骨细胞的分化具有正向调节的作用。

农用植物酵素有效成分及作用机制

农用植物酵素是以植物为主要原料,经微生物发酵制成的含有特定生物活性成分的产品,可用于种植业、养殖业、土壤改良等方面。农用植物酵素在促进作物增产,改良土壤,抑菌防虫等方面具有良好的作用,可作为构建绿色生态农业的主力产品。简述了农用植物酵素的分类、特点及各种有效成分,对农用植物酵素的增产、抑菌、土壤改良及环保作用进行总结,并对其机制进行分析,提出目前存在的问题,并对其未来的发展进行展望。

深海极端环境黑碳的地球化学特征及其环境意义

黑碳是一种广泛存在于不同环境中且抗氧化、耐分解的含碳物质。作为惰性有机碳的重要组分,黑碳深刻影响着全球碳循环。当前海洋黑碳收支的不平衡研究结果表明海洋中可能存在未知的或被忽略的黑碳来源或埋藏路径。随着深渊海沟、热液区和冷泉区等这些地球上最为极端的海洋环境黑碳研究的不断深入,已经确认这些环境中存在独特的黑碳循环过程,可能是海洋黑碳的重要源或汇。本文综述了海洋极端环境中黑碳的地球化学特征,发现深渊海沟独特的“V”字型地形有利于物质汇聚,其中的黑碳比同沉积的有机碳更为古老,黑碳年埋藏量可达约(1.0±0.5)Tg;热液区的高温流体通过“灼烧”有机质形成原位自生黑碳,其每年向海洋贡献的黑碳可达1.6~9.7Tg,是海洋黑碳的重要来源;冷泉区黑碳的源汇过程尚不清楚,但区域内丰度极高的甲烷厌氧氧化古菌最近被证明可以直接产生黑碳,其碳同位素值负偏至-60‰以下,这是迄今为止唯一的一种微生物来源黑碳,是对黑碳类型传统认识的重要补充。尽管目前已经建立海洋黑碳源汇过程的总体框架,但尚缺乏对海洋极端环境黑碳的直接形态观察及特征分析,未来的研究需要明确海洋极端环境中陆源黑碳与海洋自生黑碳的比例,以进一步了解海洋黑碳源汇过程并探讨极端环境黑碳在海洋碳循环中扮演的角色。

MEGA^(2)尚未发表的马克思晚年关于法国土地所有制的笔记

在阿姆斯特丹国际社会史研究所官网中,有一本MEGA^(2)(《马克思恩格斯全集》历史考证版)尚未发表的马克思晚年关于法国土地所有制的笔记。该笔记由德语和法语组成,封面目录由恩格斯亲笔撰写,正文部分由马克思亲笔摘录。笔记的主要内容为土地所有制相关的详细数据。结合马克思晚年的研究方向,摘录笔记是马克思对国家革命问题与“六册计划”进行的更进一步的探索。根据辨识结果,该笔记对于了解马克思晚年对待农民阶级的态度具有重要价值和意义。

基于老年综合评估的个体化康复训练对阿尔茨海默病患者认知功能、风险防范的影响

目的构建基于阿尔茨海默病(AD)患者老年综合评估(CGA)的个体化康复训练干预模式,并从认知功能、风险防范等角度进行成效分析。方法采用前瞻性随机对照研究,选取220例AD患者为研究对象,按照随机数字表法将患者均分为对照组(110例)和观察组(110例)。对照组给予常规药物治疗及康复训练,观察组增加基于CGA的个体化康复训练干预。比较2组干预前、干预3个月后的认知功能[阿尔茨海默病痴呆评定量表(ADASCog)、简易精神状态量表(MMSE)],风险防范[美国约翰霍普金斯跌倒量表(JHFRAT)、激越行为量表(CMAI)],心境状态[心境状态量表(POMS)],躯体功能[Berg平衡量表(BBS)、Barthel指数评定量表(BI)]变化。结果干预3个月后,观察组患者ADAS-Cog、JHFRAT、CMAI量表评分显著降低,MMSE量表、BBS量表评分显著升高(P<0.01),对照组干预前后比较无统计学意义(P>0.05)。干预3个月后,2组患者POMS量表活动-好动分量表、BI量表评分显著升高(P<0.01),而POMS量表中紧张-焦虑、忧郁-沮丧、愤怒-敌意、疲惫-惰性、困惑-迷惑分量表评分显著降低(P<0.01),观察组变化更明显(P<0.01)。结论基于CGA的个体化康复训练干预AD患者,可对其认知功能、跌倒风险、激越行为、心境状态、躯体功能等方面产生积极影响,是一种值得推广的模式。

前交叉韧带重建术后膝关节感染的诊断和治疗策略

目的:探讨关节镜下前交叉韧带重建术后膝关节感染的临床诊断和治疗策略。方法:选择2001年1月至2020年12月在北京大学第三医院运动医学科行关节镜下前交叉韧带重建手术且术后发生膝关节感染的病例进行回顾性分析。通过对患者术后关节感染的发病过程、临床特征、试验室检查、治疗方法及随访结果进行分析,探讨最佳的临床诊断和治疗策略。结果:20年间关节镜下前交叉韧带重建手术共27867例,术后膝关节感染65例,感染率0.23%。临床表现有体温增高[(38.7±0.5)℃]、膝关节肿痛、关节活动度受限。细菌培养阳性率69.2%,其中凝固酶阴性葡萄球菌(占75.6%)、金黄色葡萄球菌(占15.6%)最常见。保守治疗组(16例)和手术治疗组(49例)均能有效控制感染,但保守治疗组体温恢复较慢(保守治疗组5.6 d,手术治疗组1.6 d,P=0.042)。结论:前交叉韧带重建术后膝关节感染是一种发生率低,但后果严重的并发症,临床诊断建议及早进行关节腔穿刺和病原学检查,一旦确诊,建议尽早进行关节镜清理手术,并给予有效抗生素治疗。

前交叉韧带断裂三维不对称度步态分析初探

目的步态分析对于下肢损伤部位及程度描述具有重要作用,而对称度是步态特征的重要指标。本研究将在三维空间定量描述步态信息及其不对称度,深入挖掘步态信息,完善疾病异常步态特征分析。方法基于惯性步态传感器获得不同部位的冠状面-矢状面角度变化信息,反向重建步态空间矢量,构建运动曲线,形成基于三维空间角度矢量距离的运动对称性检测方法。于2017年7月至2018年1月对健康人(正常组)和单纯前交叉韧带(ACL)断裂患者(ACL组)进行特征分析,验证其效果。结果小腿、大腿和膝关节不对称度D方面两组有较好的区分效果(P<0.05)。其中小腿空间运动矢量特征对组间辨识度较高且区分相对稳定,与性别、年龄、身高、体质量指数无关。结论通过两侧惯性传感器获得左右肢体时间-冠状面-矢状面空间曲线图,在三维空间中计算相应周期所有时间点的欧式空间距离平方的平均值,可作为步态不对称度分析方法。

正渗透膜生物反应器运行过程中溶质反渗对微生物群落的影响

以氯化钠为驱动溶质,采用正渗透膜生物反应器(forward osmosis membrane bioreactor,FOMBR)处理生活污水,考察其在运行过程中溶质反渗对系统内微生物群落造成的影响。稳定运行状态下的第7、14、20天的混合液污泥样品分别称为A1、A2、A3,并对微生物群落物种丰度、群落结构、聚类等进行了分析。结果表明:正渗透膜生物反应器运行20 d内水通量从9.5 L/(m^2·h)下降到8.17 L/(m^2·h),反向盐通量从29.52 g/(m^2·h)增加到35.06 g/(m^2·h)。整个运行过程中溶质反渗对微生物群落结构的变化有着一定的影响,3个样品共产生1496个OTUs,各样品间共享的OTUs不尽相同;溶质反渗对3种样品的微生物群落多样性、菌群丰度等影响较小。PCA分析中A2和A3两个样品距离更近,组成更相似,热图聚类分析再次验证A2与A3相似性更高;3个样品斜率较小且非常接近,并且A1和A3两个样品所含物种的丰富程度和均匀程度几乎一样;3个样品的活性污泥群落结构在门、纲、目分类水平上均具有较高的多样性,各分类水平上的菌群丰度存在一定的差异。