Mechanical behavior and failure mechanism of polyurea nanocomposites under quasi-static and dynamic compressive loading

Polyurea is an elastomeric material that can be applied to enhance the protection ability of structures under blast and impact loading.In order to study the compressive mechanical properties of SiC/polyurea nanocomposites under quasi-static and dynamic loading,a universal testing machine and split Hopkinson pressure bar(SHPB)apparatus were used respectively.The stress-strain curves were obtained on polyurea and its composites at strain rates of 0.001e8000 s1.The results of the experiment suggested that increase in the strain rates led to the rise of the flow stress,compressive strength,strain rate sensitivity and strain energy.This indicates that all of the presented materials were dependent on strain rate.Moreover,these mechanical characters were enhanced by incorporating a small amount of SiC into polyurea matrix.The relation between yield stress and strain rates were established using the power law functions.Finally,in order to investigate the fracture surfaces and inside information of failed specimens,scanning electron microscopy(SEM)and micro X-ray computed tomography(micro-CT)were used respectively.Multiple voids,crazes,micro-cracks and cracking were observed in fracture surfaces.On the other hand,the cracking propagation was found in the micro-CT slice images.It is essential to understand the deformation and failure mechanisms in all the polyurea materials.

中医药辨证论治对Ⅱ~Ⅲ期结直肠癌术后早期复发转移的影响研究

目的:探讨Ⅱ~Ⅲ期结直肠癌(colorectal cancer,CRC)根治术后服用≥6个月的个体化辨证论治汤药在预防早期复发转移方面是否优于未服用中药(traditional Chinese medicine,TCM)者。方法:回顾性分析河南中医药大学第一附属医院及河南大学第一附属487例Ⅱ~Ⅲ期接受CRC根治术的患者,以是否服用≥6个月的个体化辨证论治汤药(TCM vs.Non-TCM)后早期(2年)复发转移的发生率为主要结局,采用多因素修正泊松回归评估是否服用中药与主要结局之间的关联。利用倾向评分匹配(propensity score matching,PSM)方法进行敏感性分析。结果:纳入分析TCM组103例,Non-TCM组384例。多因素修正泊松回归分析显示,TCM组发生早期复发转移的风险较低10.7%(12/103)vs.21.4%(82/384),相对危险度(relative risk,RR)为0.448,95%CI:0.261~0.769。经过1∶2比例的PSM,敏感性分析结果与多因素修正泊松回归分析的结果一致,TCM组仍显示出较低的早期复发转移风险11.1%(11/99)vs.21.2%(42/198),RR为0.464,95%CI:0.227~0.948。亚组分析显示在男性、N2(有4枚或以上区域淋巴结转移)、中-高分化的患者中,Non-TCM组和TCM组之间主要结局的差异较大(P<0.05)。生存分析显示TCM组无早期复发转移生存期显著高于Non-TCM组(P<0.05)。结论:对于Ⅱ~Ⅲ期CRC根治术后的患者,接受≥6个月的个体化辨证论治汤药后早期(2年)复发转移的风险低于未服用中药者,表明中医药辨证论治可作为CRC患者有效的选择。

Preparation and In vitro Evaluation of Polydopamine-coated Immunoadjuvant Nanoparticles

[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-glycolic acid)(PLGA)nanoparticles of imiquimod(R837)were prepared by emulsified solvent evaporation method.Dopamine was oxidized and self-polymerized to form polydopamine(PDA)under alkaline conditions,which then adhered to the surface of R837-PNPs(PDA-R837-PNPs).Particle size,Zeta potential and photothermal conversion capacity were used as indicators to select the best polymerization conditions.The photothermal conversion properties and photothermal stability of nanoparticles were investigated by near-infrared light(NIR)irradiation;the encapsulation efficiency and drug loading capacity of R837 were determined by HPLC;the cytotoxicity and cellular uptake of PDA-R837-PNPs were preliminarily investigated using 4T1 cells.[Results]PDA-R837-PNPs were prepared successfully.The optimal polymerization conditions were 0.5 mg/mL dopamine,3 h reaction time and 1.8 mg/mL R837-PNPs.The particle size of PDA-R837-PNPs was(186.7±4.81)nm;the PDI was 0.17±0.02;the Zeta potential was(-21.6±0.56)mV;the encapsulation efficiency was(58.02±0.04)%;and the drug loading capacity was(1.42±0.05)%.PDA-R837-PNPs had good photothermal conversion and photothermal stability in vitro.Cell experiments showed that PDA coating could significantly improve the celluar uptake of PNPs without obvious cytotoxicity,and PDA-R837-PNPs could produce heat to effectively kill 4T1 cells after NIR irradiation.[Conclusions]PDA-R837-PNPs have the characteristics of uniform particle size,good photothermal conversion effect and high cellular uptake rate,thus is expected to achieve efficient antitumor photoimmunotherapic effect.

Study on the mechanism of JiChuanJian in the treatment of slow-transmission constipation based on network pharmacology

Background:Slow-transit constipation remains a functional colonic disorder with the most common gastrointestinal complaint.Although JiChuanJian(JCJ)is used for treatment,little is known about its mechanism of action.We aimed to investigate the mechanism of JCJ in treating slow-transmission constipation based on network pharmacology.Methods:The chemical components and action targets of the six herbs of JCJ were retrieved from the Traditional Chinese Medicine Systematic Pharmacology Analysis Platform.Protein targets of the chemical components were obtained from the UniProt database,whiles the disease targets were retrieved from the Gene Cards database,Disgenet,and TTD databases.A Wayne diagram was drawn and the intersected targets were imported onto the STRING website for analysis to construct protein-protein interaction target interactions.The Cytoscape software constructed protein-protein interaction to identify core targets and drug-active component-target interaction networks.The Kyoto Encyclopedia of Genes and Genomes and gene ontology enrichment analyses were performed through the DAVID analysis website.Results:A total of 55 potential drug-active components of JCJ,233 drug-active ingredient targets,3215 slow-transmission constipation-related targets,and 176 drug and disease targets were identified.The core drug-active ingredients included quercetin,beta-sitosterol,stigmasterol,kaempferol and wogonin.Through enrichment analysis in DAVID database,we obtained 236 biological processes,31 cellular components and 41 molecular functions,mainly involving serotonin binding,G-protein coupled serotonin receptor activity,and neurotransmitter receptor activity,were identified.118 pathway enrichment results were obtained after the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis.Therefore,we hypothesized that the active components in JCJ,such as quercetin,β-sitosterol,and stigmasterol,may treat slow transit constipation by regulating the serotonergic synapse and cyclic adenosine monophosphate signaling pathway.Conclusion:This study showed that JCJ could play a role in treating slow-transmission constipation through multiple components,targets and pathways.

The efficacy and mechanism of fecal microflora transplantation in the treatment of slow transit constipation based on metabonomics anion mode

Background:Fecal microbiota transplantation(FMT)based on the positive ion mode of metabonomics has a good therapeutic benefit for slow transit constipation(STC)patients.However,a piece of comprehensive metabolomics information is yet to be established.The aim of the study was to explore the efficacy and mechanism of FMT in the treatment of STC under metabonomics.Methods:Eight STC patients meeting the set inclusion and exclusion criteria were enrolled and treated with FMT(three times).The Patient Assessment of Constipation-Symptoms(PAC-SYM),weekly total defecation times,and defecation frequency scores of these STC patients were compared before and after treatment.Feces and serum of STC patients before and after treatment were analyzed using 16SrDNA and metabolomics.Results:After FMT treatment,the PAC-SYM score of constipated patients decreased[(5.00±2.94)vs(5.20±2.87)],while the number of complete defecations per week increased[(2.00±1.79)vs(1.69±1.80)].The score of defecation frequency decreased[(0.83±1.03)vs(0.86±0.95)].The metabolites in the feces and serum of patients receiving FMT changed significantly(P<0.05).The results from 16SrDNA analysis showed that theαandβdiversity of the fecal microbiome changed significantly(P<0.05)after transplantation,and the contents of genera Lactobacillus,Bacillus,Succiniclasticum,Cellvibrio,and Escherichia increased in FMT treated patients.Conclusion:FMT may treat STC by increasing the beneficial intestinal flora and metabolites in the anion mode of metabolomics.

喷雾干燥结合紫外交联制备甲基丙烯酸缩水甘油酯改性丝胶中空微球及其性能

为了制备高耐水性光固化丝胶蛋白(SS)微球,采用喷雾干燥与紫外交联相结合的方法,以丝胶为原料制备了甲基丙烯酸缩水甘油酯(GMA)交联SS中空微球(GMA-g-SS),该法赋予了其良好的耐水稳定性和紫外光固化性能。优化的喷雾干燥工艺参数包括:SS浓度、进风温度及进液速度;研究了GMA浓度、二苯甲酮(BP)用量及紫外辐照时间对接枝率的影响。借助扫描电镜、红外光谱及热分析对微球表面形貌结构及稳定性进行了表征与分析。结果表明,喷雾干燥SS微球呈单分散空心结构,直径约5~20μm;GMA-g-SS微球红外光谱在1152 cm^(-1)和764 cm^(-1)处出现环氧基的吸收峰,表明GMA与SS交联成功。交联后微球呈黏连聚集状态,具有较高的紫外光固化性能且耐水稳定性大幅提升,溶失率仅为17.1%。所制备的GMA-g-SS微球具有可调的耐水稳定性和紫外光固化性,是一种有潜力的光固化3D打印生物材料。

夜间动物图像自监督学习增强与检测方法

为了解决动物夜间实时监测所面临的图像曝光度低、对比度低、特征提取困难等问题,通过研究轻量化自监督深度神经网络Zero-Denoise和改进型YOLOv8模型,来进行夜间动物目标的图像增强与精准识别。首先,通过轻量化的PDCE-Net进行第一阶段快速增强。提出了一个新的光照损失函数,并利用参数可调的Gamma校正原图与快速增强图,在基于Retinex原理和最大熵理论的PRED-Net中进行第二阶段的重增强。然后,改进YOLOv8模型,并对重增强后的图像进行目标识别。最后,在LOL数据集(low-light dataset)与自建动物数据集进行实验分析,验证Zero-Denoise网络和改进型YOLOv8模型对于夜间动物目标监测的改善效果。试验结果显示,Zero-Denoise的mAP值网络在LOL数据集上的PSNR、SSIM与MAE指标达到28.53、0.76、26.15,结合改进型YOLOv8在自建动物数据集上的mAP值比YOLOv8基线模型提升了7.1%。使用Zero-Denoise和改进型YOLOv8能获得良好的夜间动物目标图像。结果表明所提方法可用于夜间动物目标的精确监测。

A2β-酪蛋白牛奶和普通牛奶的体外消化特性和抗氧化能力评价

[目的]研究体外模拟胃肠消化对A2β-酪蛋白牛奶和普通牛奶的分子量分布及抗氧化能力的影响。[方法]以巴氏杀菌A2β-酪蛋白牛奶、超高温灭菌A2β-酪蛋白牛奶、巴氏杀菌普通牛奶、超高温灭菌牛奶为原料,通过INFOGEST 2.0对牛奶进行体外模拟胃肠消化,采用SDS-PAGE、高效液相色谱仪对体外模拟胃肠消化前后的牛奶样品进行分子量分析,并对体外模拟胃肠消化后各样品的抗氧化能力进行测定。[结果]在体外模拟胃肠消化后,4种牛奶的分子量主要分布于<1000 Da组分,A2β-酪蛋白牛奶小于500 Da组分的比例显著低于普通牛奶。超高温灭菌普通牛奶、超高温灭菌A2β-酪蛋白牛奶表现出较强的铁离子还原能力和1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力。[结论]本研究为各类牛奶产品的加工和功能特性提供基础数据。

Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile)

Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019,but the underlying mechanisms remain unclear.This study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing curves.Additionally,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable isotope.We found that C.pergracile exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water loss.Interestingly,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem tension.During the dry season,approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer.Consequently,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were observed.In summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in C.pergracile accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2019.

肠道菌群介导的不同饮食模式与高尿酸血症相关性研究进展

高尿酸血症(hyperuricemia,HUA)是一种由于尿酸生成与排泄失衡所导致的嘌呤代谢紊乱性疾病,严重时可导致痛风及肾功能损伤。目前我国HUA/痛风的患病率逐年提升,且患病人群越来越年轻化。近年来的研究表明HUA/痛风患者的肠道菌群与健康人相比存在失调现象,而不同饮食模式可介导肠道菌群影响尿酸水平。本文详细阐述了HUA/痛风病人的肠道菌群特征以及肠道菌群对尿酸的代谢机制,为HUA/痛风的预防、提早诊断和辅助治疗提供理论基础;同时总结了不同饮食模式对尿酸水平影响的相关研究进展,旨在指导患者通过调整饮食模式有效预防并延缓HUA/痛风的发生。

网络符号消费研究的理论、文化与价值面向

中国知网(CNKI)数据库和Web of Science(WOS)数据库中与网络符号消费相关的有效文献可作为数据来源,借助可视化分析软件CiteSpace,从年度发文量、发文作者、发文机构、关键词共现、关键词聚类等角度进行分析可以发现,国内外学界关于网络符号消费的研究呈现出三个面向:符号消费理论研究、网络消费文化研究以及身体与休闲研究。由此可见,关于网络符号消费的探索和研究日益呈现出多学科跨领域的发展趋势,这为当前及未来国内外学者研究网络符号消费提供一个学术史概览以及渐进式探寻的学术觅迹。

网络符号消费组织、生产和流通的运行逻辑与价值导向

在信息化时代,网络符号消费不仅是符号价值的售卖行为,本质上更是一种消费价值观的塑造与引导机制。在网络媒介的推动下,商品的生产和消费被幻化成符号的生产和消费。由此,网络符号消费的组织、生产和流通的运行逻辑,实际上就是商家在生产商品的同时也在生产符号以及符号化的价值观,其终极目的是在潜移默化中让消费者从心理或思想上接受商家的价值引导,进而在全社会形成网络符号消费主义的价值观。在这一过程中,最重要的不是商品的流通,而是信息的流通和对符号消费价值的引导。然而,在资本追逐利润的驱使下,网络符号消费的组织、生产和流通必然会产生智资矛盾,并为潜在的社会运动提供了生根发芽的土壤。就此而言,只有当正确的符号消费价值观被确立之时,大众才能获得真正的消费自由,理性的消费观也才能最终在全社会确立并得到尊崇。

综合管理对LVEF保留慢性心衰伴血流动力学异常患者心功能及MAP、CO的影响

目的探讨综合管理对左心射血分数(LVEF)保留慢性心衰伴血流动力学异常患者的心功能、平均动脉压(MAP)、心输出量(CO)影响。方法选取2021年1月—2022年2月在南阳医学高等专科学校第一附属医院就诊的LVEF保留慢性心衰血流动力学异常患者116例,按照随机数字表法分为研究组(n=58)和常规组(n=58)。常规组采用常规管理,研究组在常规组基础上联合综合护理,比较两组自我管理能力、心功能[左室舒张末径(LVDED)、心率(HR)、LVEF、6 min步行距离]、情绪状态[焦虑自评量表(SAS)、抑郁自评量表(SDS)]、MAP、CO、应对方式、自护能力、再住院次数、生活质量[明尼苏达心衰生活质量量表(MLHFQ)]、满意度。结果干预后研究组心力衰竭患者自我管理量表评分较常规组高,SAS、SDS、MLHFQ评分较常规组低(P<0.05);干预后与常规组比较,研究组LVDED、HR较低,LVEF、6 min步行距离较高(P<0.05);干预后,与常规组比较,研究组MAP、CO均较常规组高(P<0.05);干预后研究组积极应对、ESCA评分较常规组高,消极应对评分较常规组低(P<0.05);干预后、干预后3个月研究组再住院次数均低于常规组(P<0.05);干预后研究组总满意度96.55%高于常规组81.03%(P<0.05)。结论综合管理可提升LVEF保留慢性心衰血流动力学异常患者自我管理能力及自护能力,改善患者情绪状态及心功能,调节患者应对方式,还可有效改善预后,提高患者生活质量及满意度。

创伤病人早期预警评估工具研究进展

综述创伤病人早期预警相关评估工具的发展过程、主要内容及应用现状,分析各种评估工具的特点及局限性,并进行对比分析,旨在为临床工作者快速选择恰当的评估工具提供借鉴。

基于强度折减法的圆形顶管井基坑变形及稳定性分析

现行规范中有关圆形顶管井基坑的设计方法主要采用平面弹性支点法,考虑到三维空间下环形基坑支护结构的拱效应和周边土体的土拱效应,平面计算结果较实际偏于保守。为此,基于强度折减法,通过建立圆形顶管井基坑的二维、三维有限元计算模型,得到了基坑安全系数和变形量,并将计算结果与规范方法进行了比较分析。分析表明:在深径比h/r>0.9时,坑底土主要产生隆起变形;当深径比h/r小于0.9并逐渐减小后,坑底出现圆弧滑动面,土体破坏呈整体滑移模式;在三维模型下,围护结构的拱效应阻隔了坑边超载对圆弧滑动面分布的影响,周边土体的土拱效应减小了地表沉降量和围护结构变形量;基于强度折减法的基坑安全系数是规范方法中坑底抗隆起安全系数的2~3倍。

基于实时荧光定量环介导等温扩增技术快速检测发酵乳中嗜热链球菌和保加利亚乳杆菌

基于实时荧光定量环介导等温扩增(quantitative loop-mediated isothermal amplification,qLAMP)技术建立发酵乳中嗜热链球菌和保加利亚乳杆菌活菌数快速定量方法。通过优化嗜热链球菌和保加利亚乳杆菌叠氮溴化丙锭(propidium monoazide,PMA)处理条件,对菌浓度对数与相应的循环阈值进行线性拟合,构建标准曲线,建立PMA-qLAMP检测方法。结果表明,该方法对嗜热链球菌的最低定量限为7.2×10^(3) CFU/g,对保加利亚乳杆菌的最低定量限为5.6×10^(4) CFU/g,将该方法应用于市售发酵乳产品活菌数定量检测,显示出良好的灵敏度和实用性。

草酸钙酸分解的热力学分析

为阐明草酸钙渣酸分解过程的热力学,基于同时平衡原理、质量守恒原理、电中性原则,以盐酸和硫酸为分解药剂,计算和绘制草酸钙酸分解的热力学平衡图,并结合实验验证。研究结果表明:单因素实验结果与热力学计算结果的趋势一致,且部分情况的实验值和计算值吻合;草酸钙是较稳定的沉淀,在pH=4~13的范围内,维持较低溶解水平;在盐酸体系中,氯化钙和草酸对草酸钙的溶解有显著抑制作用,而在硫酸体系中,硫酸钙的生成使溶液钙浓度维持在较低水平,从而促进草酸钙的分解;硫酸参与草酸钙分解的反应率随初始酸度增加而增加,硫酸浓度为4 mol/L时,硫酸的反应率可达39.7%;而盐酸的反应率几乎不受初始酸度的影响,维持在5.4%的较低水平。此外,硫酸参与草酸钙分解的反应率随初始草酸浓度增加而下降,但在相同初始草酸浓度下,硫酸参与草酸钙分解的反应率明显比盐酸的高。

Investigation of fluorescence resonance energy transfer ultrafast dynamics in electrostatically repulsed and attracted exciton-plasmon systems

Following the gradual maturation of synthetic techniques for nanomaterials,exciton-plasmon composites have become a research hot-spot due to their controllable energy transfer through electromagnetic fields on the nanoscale.However,most reports ignore fluorescence resonance energy transfer(FRET)under electrostatic repulsion conditions.In this study,the FRET process is investigated in both electrostatic attraction and electrostatic repulsion systems.By changing the Au:quantum dot ratio,local-field induced FRET can be observed with a lifetime of ns and a fast component of hundreds of ps.These results indicate that the intrinsic transfer process can only elucidated by considering both steady and transient state information.

塔里木盆地绿洲带地下水咸化机制

采用Durov图、PMF模型、Gibbs图、离子比值法和饱和指数法对2016~2018年采集的1326组地下水样品进行分析,揭示研究区地下水中盐分的来源及高盐地下水形成的驱动因素.结果表明:在研究区绿洲带微咸水和咸水占比分别为37.2%和19.1%,水化学类型主要为SO_(4)·Cl型;在微咸水、咸水、盐水和卤水中岩盐、石膏等蒸发盐岩的持续溶解是导致高盐地下水形成的主要驱动因素,Cl^(-)、SO_(4)^(2-)、 Na^(+)与TDS(P<0.001)及岩盐、石膏的SI值与TDS(P<0.001)之间均呈现出极显著的正相关性,也证实了这一点;冲积平原区较差的地下水动力条件、细粒岩性和弱碱性的水化学环境为地下水中盐分的富集创造了有利条件,蒸发浓缩作用和阳离子交换作用是形成高盐地下水的次要因素;由于人类活动的影响,导致承压水区高TDS潜水沿井壁入渗补给承压水含水层,也是加剧深层地下水咸化的潜在因素.