Mapping out the reaction network of humin formation at the initial stage of fructose dehydration in water

The formation of humins hampers the large-scale production of 5-hydroxymethylfurfural(HMF)in biorefinery.Here,a detailed reaction network of humin formation at the initial stage of fructose-to-HMF dehydration in water is delineated by combined experimental,spectroscopic,and theoretical studies.Three bimolecular reaction pathways to build up soluble humins are demonstrated.That is,the intermolecular etherification of β-furanose at room temperature initiates the C12 path,whereas the C-C cleavage of a-furanose at 130-150℃ leads to C11 path,and that of open-chain fructose at 180℃ to C11' path.The successive intramolecular dehydrations and condensations of the as-formed bimolecular intermediates lead to three types of soluble humins.We show that the C12 path could be restrained by using HCl or AlCl_(3) catalyst,and both the C12 and C110 paths could be effectively inhibited by adding THF as a co-solvent or accelerating heating rate via microwave heating.

综合有机合成实验苯佐卡因的课程思政设计

将传统的合成路线和条件都给定的综合有机实验“苯佐卡因的合成”,改造成路线可设计、条件可优化的创新性实验。学生通过文献调研、综合分析以及评估合成策略和具体实验条件,提出兼顾宏观(路线)和微观(具体条件)的改进实验方案,规避原实验的局限性和不足。根据学生专业和培养方案的不同,开放部分或全部“权限”给学生,从不同层级原料出发,设计绿色、高效的合成路线,确定具体的实验方案;或根据建议路线,调整和优化实验条件,使学生在得到基础实验操作技能训练的基础上,其绿色、高效、可持续发展的合成理念也得到进一步升华。鼓励学生运用科学思维,将学科前沿成果引入实验实践中,培养学生科学创新能力。引导学生从全局出发,提升团队合作意识和能力。

Influences of fractional separation on the structure and reactivity of wheat straw cellulose for producing 5-hydroxymethylfurfural

High-efficient production of 5-hydroxymethylfurfural(HMF),a“sleeping giant”in sustainable chemistry,from cellulose depends significantly on the effective separation of cellulose from lignocellulosic biomass.Herein,we report the fractional separation of wheat straw cellulose(WSC)from wheat straw under solvothermal conditions using a mixed solvent of γ-valerolactone(GVL)and H_(2)O as the separating solvent,wherein the impacts of fractional separation parameters(solvent composition,temperature,and time)on removals of lignin and hemicellulose as well as purity and recovery of cellulose were studied by a Box-Behnken Design of response surface method.The optimization of the solvothermal parameters enabled an optimal fractional separation condition(V_(GVL):~60.0%,T:205℃,t:~1.7 h)that led to a higher purity(89.4%)and recovery(86.7%)of cellulose in WSC.A further correlation of the removals of lignin and hemicellulose as well as purity and recovery of cellulose with the yield of HMF excluded an independent influence of the above factors.Instead,a comprehensive contribution of high fractional separation efficiency(defined as the product of cellulose purity and recovery)and low crystallinity of WSC was found to improve the HMF yield.However,the heat-and freeze-dryings of WSC after the solvothermal separation were found to lower the HMF molar yield because it re-improved the crystallinity of WSC.A high HMF molar yield of 58.6%was achieved after reacting wet-WSC in a mixed solvent of 1,4-dioxane and H_(2)O at 180℃for 20 min,which was 1.5 fold higher than that from microcrystalline cellulose.This work highlights the importance of enhancing the fractional separation efficiency of cellulose from lignocellulosic biomass while avoiding the drying process for future HMF biorefinery.

Waste Mg alloys hydrogen production from seawater:An integrative overview of medium optimization,hydrogen-producing materials,underlying mechanisms,innovative technologies,and device development

In response to global carbon neutrality targets,there is an urgent need for large-scale,clean hydrogen production technologies to supplant fossil fuels and underpin the establishment of a‘hydrogen economy’.The prospect of large-scale on-site green hydrolysis of Mg-based materials for hydrogen production has attracted wide attention.Aiming at the problems of easy formation of inert oxide layer on its surface and the production of Mg(OH)_(2) to hinder the hydrolysis process,it is urgent to explore efficient,low-cost and green modification strategies.In this work,the green modification strategy for hydrolyzing hydrogen production of Mg-based materials was summarized,and the fast initial kinetics and high hydrogen production rate could be achieved by adjusting hydrolysis medium conditions and modifying Mg-based material.The significance of hydrolytic hydrogen production technology and device development for the realization of Mg-based hydrolytic hydrogen production was evaluated.Meanwhile,this work looks forward to the future direction of hydrogen production modification by hydrolysis of Mg-based alloy,and gradually optimizes the hydrolysis performance of industrial multi-component waste Mg alloy under the premise of green hydrogen production,and proposes the goal of efficient modification of waste Mg alloy,high-quality utilization of seawater,and low-cost and controllable hydrogen production process.

Cadherin-18 loss in prospermatogonia and spermatogonial stem cells enhances cell adhesion through a compensatory mechanism

Extracellular membrane proteins are crucial for mediating cell attachment,recognition,and signal transduction in the testicular microenvironment,particularly germline stem cells.Cadherin 18(CDH18),a type Ⅱ classical cadherin,is primarily expressed in the nervous and reproductive systems.Here,we investigated the expression of CDH18in neonatal porcine prospermatogonia(ProSGs)and murine spermatogonial stem cells(SSCs).Disruption of CDH18 expression did not adversely affect cell morphology,proliferation,self-renewal,or differentiation in cultured porcine ProSGs,but enhanced cell adhesion and prolonged cell maintenance.Transcriptomic analysis indicated that the down-regulation of CDH18 in ProSGs significantly up-regulated genes and signaling pathways associated with cell adhesion.To further elucidate the function of CDH18 in germ cells,Cdh18 knockout mice were generated,which exhibited normal testicular morphology,histology,andspermatogenesis.Transcriptomic analysis showed increased expression of genes associated with adhesion,consistent with the observations in porcine ProSGs.The interaction of CDH18withβ-catenin and JAK2 in both porcine ProSGs and murine SSCs suggested an inhibitory effect on the canonical Wnt and JAK-STAT signaling pathways during CDH18 deficiency.Collectively,these findings highlight the crucial role of CDH18 in regulating cell adhesion in porcine ProSGs and mouse SSCs.Understanding this regulatory mechanism provides significant insights into the testicular niche.

Effect of fermented Rosa roxburghii Tratt fruit juice on gut microbiota in a dextran sulfate sodium-induced colitis mouse model

This study mainly investigated the regulatory effect of Rosa roxburghii Tratt fruit juice fermented by Lacticaseibacillus paracasei SR10-1(LAB-RRTJ)on modulating gut microbiota in dextran sulfate sodium(DSS)-induced ulcerative colitis in mice.Compared to control group,DSS induction decreased body weight of mice,indexes of Shannon,Simpson,Chao1 and Faith_pd,and increased disease activity index(DAI)and levels of interleukin 1β(IL-1β),IL-6,tumor necrosis factorα(TNF-α)and interferon-γ(IFN-γ);And this induction also led to an increase in Proteobacteria,Verrucomicrobia and Actinobacteria at phylum level,harmful bacterial species richness at genus level,and relative richness of S.sciuri,Desulfovibrio C21_c20,R.gnavus and Akkermansia muciniphila at species level,and a decrease in Firmicutes at phylum level and relative richness of B.acidifaciens in mice.LAB-RRTJ increased body weight of mice with DSS induced ulcerative colitis(UC)and indexes of Shannon,Simpson,Chao1 and Faith_pd,reduced DAI and the content of four infl ammatory factors and improved gut microbiota imbalance in DSS induced UC mice.Besides,the number of operational taxonomic units(OTUs)increased,α-diversity andβ-diversity were restored and similar to those in mice in the control group after LAB-RRTJ treatment.Compared with the positive drug treatment group,LAB-RRTJ has a better effect on regulating gut microbiota diversity in colitis mice.Correlation analysis showed that infl ammatory factors were positively correlated with harmful bacteria and negatively correlated with beneficial bacteria which commonly found in some colitis mice.Taken together,our study demonstrated that LAB-RRTJ could alleviate DSS-induced colitis in mice through the modulation of infl ammatory cytokines and gut microbiota composition.

Short-term train arrival delay prediction:a data-driven approach

Purpose-To optimize train operations,dispatchers currently rely on experience for quick adjustments when delays occur.However,delay predictions often involve imprecise shifts based on known delay times.Real-time and accurate train delay predictions,facilitated by data-driven neural network models,can significantly reduce dispatcher stress and improve adjustment plans.Leveraging current train operation data,these models enable swift and precise predictions,addressing challenges posed by train delays in high-speed rail networks during unforeseen events.Design/methodology/approach-This paper proposes CBLA-net,a neural network architecture for predicting late arrival times.It combines CNN,Bi-LSTM,and attention mechanisms to extract features,handle time series data,and enhance information utilization.Trained on operational data from the Beijing-Tianjin line,it predicts the late arrival time of a target train at the next station using multidimensional input data from the target and preceding trains.Findings-This study evaluates our model’s predictive performance using two data approaches:one considering full data and another focusing only on late arrivals.Results show precise and rapid predictions.Training with full data achieves aMAEof approximately 0.54 minutes and a RMSEof 0.65 minutes,surpassing the model trained solely on delay data(MAE:is about 1.02 min,RMSE:is about 1.52 min).Despite superior overall performance with full data,the model excels at predicting delays exceeding 15 minutes when trained exclusively on late arrivals.For enhanced adaptability to real-world train operations,training with full data is recommended.Originality/value-This paper introduces a novel neural network model,CBLA-net,for predicting train delay times.It innovatively compares and analyzes the model’s performance using both full data and delay data formats.Additionally,the evaluation of the network’s predictive capabilities considers different scenarios,providing a comprehensive demonstration of the model’s predictive performance.

早期近端胃癌行腹腔镜辅助下近端胃切除双通路吻合术的短期手术疗效观察

目的为评估早期近端胃癌保功能手术的可行性与益处,比较早期胃癌患者行腹腔镜辅助近端胃切除双通道吻合术与腹腔镜辅助全胃切除Roux-en-Y消化道重建术的短期手术效果。方法选取2016年5月-2018年5月29例早期近端胃癌患者接受近端胃切除双通道吻合术;同时选取该院2015年6月以来行全胃切除Roux-en-Y消化道重建术的早期近端胃癌患者,做人口统计学信息、合并症、肿瘤特征和TNM分期配对,对两组患者的围术期和短期手术结果进行比较。结果两组患者的术后病理学特征相近,两组患者均无中转开腹及均未出现术中并发症,两组患者手术时间、术中出血量、术后肛门首次排气时间、首次进食时间及术后住院时间比较,差异均无统计学意义,双通道组淋巴结清扫量(16.73±5.68)枚明显少于全胃切除组(21.43±4.09)枚,两组比较,差异有统计学意义(P=0.023)。每组患者均无吻合口瘘、吻合口出血、反流性食管炎、切口感染及淋巴瘘的记录,两组患者并发症发生率和围术期炎症反应比较,差异无统计学意义。术后随访3个月发现,较之全胃切除Roux-en-Y消化道重建术患者,近端胃切除双通道吻合术患者生活满意度高,两组患者术后体重均较术前下降,其中全胃切除组患者术后体重下降较双通道组比例更高,两组比较,差异有统计学意义(P<0.05);两组患者术前和术后1个月血红蛋白比较,差异无统计学意义,术后2和3个月随访结果显示,双通道组血红蛋白量较全胃切除组高,两组比较,差异有统计学意义(P<0.05);在术前、术后1及2个月,两组患者的血清白蛋白量比较,差异无统计学意义,术后3个月时,双通道组患者血清白蛋白量(41.45±3.68)g/L明显高于全胃切除组(38.45±4.96)g/L,差异有统计学意义(P=0.035)。结论早期近端胃癌行腹腔镜辅助下近端胃切除双通道吻合术有较好的可行性和安全性,近期疗效满意,与全胃切除组比较,双通路术式不增加围术期并发症的发生率,而患者术后营养状况更好,术后体重下降率更低。

我院2011—2016年革兰阳性菌耐药监测数据研究

目的通过对我院2011—2016年住院和门诊患者革兰阳性菌分离比例、耐药情况的分析研究,掌握耐药流行趋势,为抗生素的合理使用提供参考依据。方法对2011年1月—2016年12月本院住院与门诊患者等各种标本进行分离培养,采用全自动细菌鉴定仪和API手工鉴定系统进行细菌鉴定,参照美国临床实验室标准化委员会(CLSI)文件M100-S26标准进行药敏试验和结果判定;后将6年的数据用Whonet 5.6中文版软件及SPSS 13.0软件进行数据统计分析。结果 2011—2016年共分离的革兰阳性菌15,123株占总分离细菌数50,412株的29.99%;其中金黄色葡萄球菌、肺炎链球菌、表皮葡萄球菌、粪肠球菌、屎肠球菌、β-溶血链球菌、草绿色链球菌群排名前7位,分别占总细菌的6.48%~7.78%、5.05%~6.47%、1.25%~2.08%,0.91%~1.26%、0.62%~1.02%,0.55%~1.05%和0.60%~1.01%,无统计学差异(P>0.05)。趋势图显示β-溶血链球菌、草绿色链球菌分离比例有逐步上升趋势;从2014—2016年粪肠球菌出现下降趋势,屎肠球菌出现上升趋势,到2016年屎肠球菌比例高于粪肠球菌比例;耐甲氧西林表皮葡萄球菌(methicillin resistant Staphylococcus epidermidis,MRSE)比例在52.30%~77.60%之间,耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)比例在32.20%~46.80%之间,都有逐年升高趋势;耐青霉素的肺炎链球菌比例在1.70%~3.10%之间;未发现耐万古霉素和利奈唑胺的金黄色葡萄球菌和表皮葡萄球菌,金黄色葡萄球菌对四环素、环丙沙星、左氧氟沙星耐药率有一定下降趋势;肠球菌耐药性相对比较稳定。肺炎链球菌对红霉素、克林霉素、复方磺胺甲噁唑、四环素耐药率较高;草绿色链球菌对氨苄西林、头孢噻肟耐药率呈逐年上升趋势;β-溶血链球菌对常见抗生素保持高敏感性,但是近年出现了对左氧氟沙星的耐药菌株。结论革兰阳性菌分离比例比较稳定,β-溶血链球菌、草绿色链球菌、屎肠球菌分离比例有逐年上升趋势。MRSA比例高于全国平均水平,MRSE比例低于全国平均水平,但都有上升趋势。青霉素耐药肺炎链球菌(penicillin resistant Streptococcus pneumoniae,PRSP)和耐万古霉素肠球菌(vancomycin resistant Enterococcus,VRE)比例保持在全国较低水平。金黄色葡萄球菌耐药性不稳定,变化较大;表皮葡萄球菌耐药性相对稳定。两种葡萄球菌对氟喹诺酮类药物保持较低耐药率,并有逐年下降趋势,肺炎链球菌对头孢噻肟的耐药率逐年上升;多重耐药的草绿色链球菌逐年增加。加强本院或本地区范围内的耐药监测数据研究,发现本地细菌耐药特点更有利于指导临床合理使用抗菌药物。

通过实验教学加深对理论知识的理解——以“气相色谱实验”教学为例

仪器分析是化学专业学生的必修课,其中涉及的基本概念原理比较抽象、难以理解。将理论知识与实验教学相结合可加深学生对理论知识的理解。本文以气相色谱实验为例,通过研究实验条件如柱温、载气流量、进样量以及毛细管气相色谱分流比对分离度的影响,帮助学生理解书本知识,同时也培养了学生科研思维以及分析问题、解决问题的能力。

浅谈几种同分异构体的质谱解析

质谱解析是波谱分析课程教学的重点和难点,有机化合物裂解规则是质谱解析的关键,掌握有机化合物质谱的碎裂规律对于化合物结构解析很有帮助。本文从本科教学的实际出发,对三类常见同分异构体羧酸-酯、醇-醚及直链-支链化合物的质谱碎裂规律进行梳理,并通过具体质谱解析实例帮助学生学习、掌握有机化合物的基本裂解规律,提高质谱解析能力。

支架联合抽吸取栓术治疗老年颅内大血管急性闭塞的疗效观察

目的探讨支架联合抽吸取栓术治疗老年颅内大血管急性闭塞的效果及对患者血流动力学、神经功能和预后的影响。方法选取2016年10月—2019年10月宿州市第一人民医院和贵州医科大学附属医院收治的老年颅内大血管急性闭塞患者62例,按照随机数字表法分为观察组和对照组,每组31例。对照组采用单纯支架取栓,观察组采用支架联合抽吸取栓。比较两组静脉和动脉再通时间和取栓次数;术前和术后3个月神经功能缺损(CSS)评分、Barthel指数量表(BI)评分、颈动脉最小血流量(Qmin)和最小血流速度(Vmin)变化;以及术后3个月预后情况。结果观察组静脉和动脉再通时间长于对照组(P<0.05),取栓次数少于对照组(P<0.05)。观察组手术前后CSS评分、BI评分的差值大于对照组(P<0.05)。观察组手术前后颈动脉Qmin和Vmin的差值大于对照组(P<0.05)。观察组预后良好率高于对照组(P<0.05)。结论支架联合抽吸取栓术治疗老年颅内大血管急性闭塞疗效较好,可改善患者血流动力血管、神经功能及预后。

华东理工大学应用化学一流专业建设的思考与实践

建设高水平本科教育、全面提高人才培养能力,实施一流本科专业“双万计划”具有重要意义。华东理工大学应用化学专业自1985年成立以来,形成了鲜明的专业特色,本文从专业培养目标定位、专业综合改革措施等方面总结了专业改革的思路、实践的经验和取得的成效,并指出了专业建设的不足和持续改进的方向。

后腹腔镜肾实质切开取石术治疗肾脏铸形结石(附23例报告)

目的探讨后腹腔镜技术处理肾脏铸形结石的手术要点与临床应用价值。方法 2013年8月-2017年10月,对23例不适合经皮肾镜取石术(PCNL)的患者给予后腹腔镜肾实质切开取石,结石均为单侧,至少占据一个肾盏和全部肾盂,平均直径2.8(2.3~3.8)cm。术中阻断肾动脉后,经吸引器注入冰水给予肾表面降温,沿Brodel线切开肾实质取出结石,根据肾实质厚度以QuillTM双向倒刺线进行全层或分层连续缝合关闭创缘。结果 23例手术均获成功。手术时间75~135 min,中位数95 min;肾脏热缺血时间17~35 min,中位数25 min;术中估计失血量25~350 ml,中位数105 ml,术中术后均未输血。术后5例出现血尿,均在3.0 d后消失;另有3例出现漏尿,于术后3.0~5.0 d消失。术后复查无明显残石。术后平均随访10(2~18)个月,静脉尿路造影(IVU)显示患肾梗阻程度明显减轻。结论后腹腔镜肾实质切开取石术是一种安全、有效的微创手术方法,对于不适合行PCNL的患者,有望作为PCNL的替代治疗措施,但需进一步增加例数并观察远期疗效。

家族性腺瘤性息肉病47例临床分析

目的探讨家族性腺瘤性息肉病(familial adenomatous polyposis,FAP)的临床表现、病理特征、癌变危险因素及治疗方法 .方法收集江苏省人民医院47例家族性腺瘤性息肉病患者的临床资料,回顾分析其临床表现、病理特征、癌变情况及治疗方法 .结果 47例患者中29例患者表现为黑便或便血,22例发生大便性状改变,腹痛16例,腹胀11例,9例患者伴发胃息肉,4例伴发十二指肠息肉,2例术后发生硬纤维瘤.病理结果以管状腺瘤及绒毛管状腺瘤为主,少数表现为增生性息肉或幼年性息肉.16例患者发生癌变,发现年龄≥40岁及腺瘤直径>2 cm者与40岁以下及腺瘤小于2 cm的患者癌变差异有统计学意义(P<0.05),年龄(OR=1.084,95%CI:1.016-1.157)及腺瘤大小(OR=10.264,95%CI:1.526-69.035)为影响FAP癌变的危险因素.所有患者均行结直肠切除或内镜下治疗,4例癌变患者术后辅以化疗.结论家族性腺瘤性息肉病以结直肠生长大量息肉为主要特征,可伴有一系列肠外表现.病理表现以管状腺瘤及绒毛管状腺瘤为主.发现年龄及腺瘤大小为影响FAP癌变的危险因素.预防性结直肠切除和内镜下监测仍然是目前治疗FAP的主要措施.

乌司他丁对百草枯中毒患者肺纤维化程度及近期生存情况的影响

目的:探讨乌司他丁对百草枯中毒患者肺纤维化程度及近期生存情况的影响。方法:选择90例百草枯中毒患者,随机分为两组,对照组45例采用常规治疗,干预组45例在常规治疗的基础上给予乌司他丁治疗5 d。治疗后7 d,对两组患者治疗前后促炎细胞因子[白细胞介素-18(IL-18)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、高迁移率族蛋白B1(HMGB1)],促纤维化相关因子[基质金属蛋白酶-9(MMP-9)、转化生长因子-β_(1)(TGF-β_(1))],氧化应激指标[丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)]以及肝功、肾功、心肌酶指标[谷丙转氨酶(ALT)、谷草转氨酶(AST)、血肌酐(SCr)、肌酸激酶同工酶(CK-MB)等生化指标]进行比较,依据肺CT影像计算并对比两组的肺纤维化程度评分。随后分别对比两组患者7、14、28 d的病死率并采用Kaplan-Meier法对比两组的生存情况。结果:治疗前两组患者的促炎细胞因子、促纤维化相关因子、氧化应激指标以及ALT、AST、SCr、CK-MB等生化指标比较均无统计学差异(均P>0.05)。治疗后7 d,对照组死亡4例(其中1例为第7天死亡)、干预组死亡3例,两组患者的IL-18、TNF-α、IL-6、HMGB1、MMP-9、TGF-β_(1)均较前升高但干预组低于对照组,MDA较前降低且干预组低于对照组,SOD和CAT较前升高且干预组高于对照组,ALT、AST、SCr、CK-MB虽均较前升高但干预组均低于对照组,差异均有统计学意义(均P<0.05);干预组的肺纤维化程度评分显著低于对照组(P<0.05)。干预组的7 d病死率及生存时间与对照组比较无统计学差异(P>0.05),但14 d病死率显著低于对照组且生存时间显著高于对照组(均P<0.05),然而28 d病死率及生存时间与对照组比较却无统计学差异(均P>0.05)。结论:在常规治疗的基础上联合乌司他丁治疗百草枯中毒,可改善肺纤维化程度及肝、肾、心肌等损伤情况,且可降低14 d病死率并改善生存时间;其机制为乌司他丁可改善患者的炎性反应及氧化应激失衡、改善肺纤维化,进而降低百草枯所致器官损伤。

家庭养育环境和养育者共心力对婴儿气质的影响

为了探索家庭养育环境和养育者共心力对婴儿气质的影响,本研究采用结构式观察法,对42个家庭的母亲和祖辈的共心力进行测量,并采用母亲报告的问卷法测量婴儿气质。结果发现,与非共同养育环境下的婴儿相比,共同养育环境下的婴儿活动性水平和舒适性水平更高;共同养育环境下的母亲“合适心理评论”与婴儿气质中的“新异刺激引起的负性情绪”显著负相关,非共同养育环境下未发现类似的关系;共同养育环境下的祖辈“合适心理评论”通过母亲“合适心理评论”的中介作用间接影响婴儿气质中的“新异刺激引起的负性情绪”。祖辈参与下的共同养育虽然不直接影响婴儿气质,但由于能够分担育儿压力,所以有利于母亲与婴儿之间的良好联结。促进祖辈与父母对婴儿的共同养育及他们之间的和谐相处,提高母亲的共心力水平,可以为婴儿气质发展创设更好的家庭养育环境。

Dynamic compression characteristics of layered rock mass of significant strength changes in adjacent layers

Layered rock mass of significant strength changes for adjacent layers is frequently observed in underground excavation,and dynamic loading is a prevalent scenario generated during excavation.In order to improve the driving efficiency and reduce engineering accidents,dynamic compression characteristics of this kind of rock mass should be understood.The dynamic properties of a layered composite rock mass are investigated through a series of rock tests and numerical simulations.The rock mass is artificially made of various proportions of sand,cement and water to control the distinct strength variations at various composite layers separated by parallel bedding planes.All rock specimens are prefabricated in a specially designed mould and then cut into 50 mm in diameter and 50 mm in height for split Hopkinson pressure bar(SHPB)dynamic compression testing.The test results reveal that increasing strain rate causes the increases of peak strength,σ_p,and the corresponding failure strain,ε_p,while the dynamic elastic modulus,E_d,remains almost unchanged.Interestingly,under the same strain rates,Ed of the composite rock specimen is found to decline first and then increase as the dip angle of bedding plane increases.The obtained rock failure patterns due to various dip angles lead to failure modes that could be classified into four categories from our dynamic tests.Also,a series of counterpart numerical simulations has been undertaken,showing that dynamic responses are in good agreement with those obtained from the SHPB tests.The numerical analysis enables us to Iook into the dynamic characteristics of the composite rock mass subjected to a broader range of strain rates and dip angles than these being tested.

双酚A-聚碳酸酯湿热老化链内/链端水解反应机理的粗粒化分子动力学-动力学蒙特卡洛模拟

提出了用粗粒化分子动力学与动力学蒙特卡洛相结合的模拟方法(C-K方法),在较大空间和时间尺度下研究了不同初始聚合度及水含量的聚碳酸酯(PC)的湿热老化规律及链内/链端水解分子机理。发现在多数条件下PC的水解反应主要发生在链内,且链内水解位置多位于距链端2~20聚合度处,这可能与链内反应位点远多于链端有关。降低PC的初始聚合度使得老化前期链端水解比例上升,在一定范围内降低PC的水含量则对链端/链内水解机理影响不大。

One-step laparoscopic pancreatic necrosectomy verse surgical step-up approach for infected pancreatic necrosis:a case-control study

BACKGROUND:The surgical step-up approach often requires multiple debridements and might not be suitable for infected pancreatic necrosis(IPN)patients with various abscesses or no safe route for percutaneous catheter drainage(PCD).This case-control study aimed to investigate the safety and effectiveness of one-step laparoscopic pancreatic necrosectomy(LPN)in treating IPN.METHODS:This case-control study included IPN patients undergoing one-step LPN or surgical step-up in our center from January 2015 to December 2020.The short-term and long-term complications after surgery,length of hospital stay,and postoperative ICU stays in both groups were analyzed.Univariate and multivariate logistic regression analyses were performed to explore the risk factors of major complications or death.RESULTS:A total of 53 IPN patients underwent one-step LPN and 37 IPN patients underwent surgical step-up approach in this study.There was no significant difference in the incidence of death,major complications,new-onset diabetes,or new-onset pancreatic exocrine insufficiency between the two groups.However,the length of hospital stay in the one-step LPN group was significantly shorter than that in the surgical step-up group.Univariate regression analysis showed that the surgical approach(one-step/step-up)was not the risk factor for major complications or death.Multivariate logistic regression analysis indicated that computed tomography(CT)severity index,American Society of Anesthesiologists(ASA)class IV,and white blood cell(WBC)were the significant risk factors for major complications or death.CONCLUSION:One-step LPN is as safe and effective as the surgical step-up approach for treating IPN patients,and reduces total hospital stay.