摘要：AIM:To investigate a newly designed stent and its dilatation effect in a rabbit model of benign esophageal ***:Thirty-four New Zealand white rabbits underwent a corrosive injury in the middle esophagus for esophageal stricture *** rabbits with a successful formation of esophageal strictures were randomly allocated into two *** control group(n = 15) was implanted with a conventional stent,and the study group(n= 15) was implanted with a detachable "pieced" *** study stent(30 mm in length,10 mm in diameter) was composed of three covered metallic pieces connected by surgical suture *** stent was collapsed by pulling the suture lines out of the *** weeks after stricture formation,endoscopic placement of a conventional stent or the new stent was *** extraction was carried out four weeks *** extraction rate,ease of extraction,migration,complications,and survival were ***:Stent migration occurred in 3/15(20%)animals in the control group and 2/15(13%) animals in the study group;the difference between the two groups was not statistically *** the end of four weeks,the remaining stents were successfully extracted with the endoscope in 100%(11/11) of the animals in the study group,and 60%(6/10)of the animals in the control group;this difference was statistically significant(P < 0.05).There was no difference in the mean number of follow-up days between the control and study groups(25.33 vs25.85).Minor bleeding was reported in five cases in the study group and four in the control *** were no severe complications directly associated with stent implantation or extraction in either of the two ***:In this experimental protocol of benign esophageal strictures,the novel "pieced" stent demonstrated a superior removal rate with a similar migration rate compared to a conventional stent.

摘要：p53是迄今发现突变频率最高的一种肿瘤抑制蛋白质,突变会导致p53抑癌功能丧失并诱导癌症的发生。绝大多数的突变发生在p53的核心DNA结合区域(p53C),其中Y220C是研究较多的一种突变体。虽然已有研究表明该突变能够降低p53C的结构稳定性,但其影响p53C构象转换的分子机制尚不清晰。本文利用分子动力学(MD)模拟方法研究了p53C突变体Y220C(p53C-Y220C)的结构变化,发现Y220C突变主要影响Y220C cluster区域(包括残基138-164和215-238),且Y220C突变减少了Y220C cluster的β-折叠含量。进一步分析发现,Y220C突变不仅直接破坏突变氨基酸与周围氨基酸Leu145和Thr155之间的氢键,而且降低了Y220C cluster区域的折叠片S3和S8之间的氢键数量,使Y220C突变所形成的亲水性空腔变大,加速了水分子进入该蛋白质内部,并最终导致了p53C-Y220C变性。MD模拟结果揭示了Y220C突变影响p53C结构转换的分子机制,该研究对p53C-Y220C突变体高效稳定剂的筛选和设计具有重要意义。

摘要：Q460高强钢焊接波形钢腹板抗剪强度的计算是波形钢腹板组合梁桥设计的关键问题。本文综合考虑焊接残余应力、初始几何缺陷和几何参数的影响,通过数值模拟的方法对3种常用波型的Q460高强钢波形钢腹板梁进行了非线性剪切屈曲研究。通过对比有限元模型的计算值和试验实测值,证明了有限元模型的正确性;分析了焊接残余应力和初始几何缺陷对高强钢焊接波形钢腹板梁抗剪强度的影响;将有限元结果与既有的波形钢腹板梁抗剪强度计算公式进行比较,并提出了抗剪强度下限计算公式。结果表明:所建立的有限元模型可用于计算波形钢腹板梁的初始刚度、极限抗剪强度、荷载-位移曲线和残余抗剪强度;焊接残余应力对抗剪强度影响较小,初始几何缺陷则具有显著影响,影响程度在剪切长细比λ_(s)>0.6后愈发明显;随着腹板厚度的增加,波形钢腹板的初始刚度和抗剪强度显著提升;波形钢腹板高度越小,钢材的利用率和残余抗剪强度越高;波形钢腹板的残余抗剪强度与波纹深度无关,而与破坏模式有关。研究成果可为高强钢焊接波形钢腹板梁抗剪强度计算与分析提供参考。

摘要：为改善柿庄区块水平井压裂排采效果较差的现状,从柿庄区块7口煤层气直井压裂微裂缝监测解释着手分析,认为导致排采效果不佳的重要因素是压裂改造实际作用在煤层的支撑剂仅有10%左右。为使压裂施工更多地作用在煤层,提出了人工诱导方法形成水平裂缝的新思路,即在煤层内利用高效压裂液携砂诱导形成水平裂缝。通过室内试验和裂缝形态机理研究,并对柿庄区块J水平井进行了现场试验,压裂施工设计排量为8.5~9.5 m3/min,入井液量约1 000 m3,砂比为9%,压裂成功率达到100%,达到设计要求。微地震监测结果表明：压裂裂缝形态复杂,水平分量体积百分数在80%以上,主要表现为水平裂缝特征,充分说明技术具有可行性。人工诱导裂缝技术可为水平井提高压后产量提供技术保障。

摘要：大量分布式新能源的接入,导致配电网面临电压越限、网损增加等严峻挑战。针对无功电压控制问题,深度强化学习能够有效解决传统优化方法在模型依赖和求解速度方面的不足。然而现有深度强化学习方法在面对大规模配网复杂场景时,特征提取能力有限,控制效果欠佳,因此该文提出一种考虑自注意力和时序记忆的多智能体深度强化学习控制策略。首先,将无功电压控制问题建模为分布式部分可观测马尔可夫决策过程;其次,基于自注意力编码器和时序记忆神经元,设计了特征提取网络、辅助训练网络、改进策略网络和改进价值网络4种神经网络结构;然后,引入自监督学习,介绍所提算法的中心式训练和分布式执行过程;最后,在改进的IEEE 141节点配网系统上进行了算例测试。实验结果表明,所提控制策略能够有效提取状态特征、记忆时序信息、辨识关键元件,表现出更加优异的稳压减损控制效果,同时具有较好的鲁棒性、可解释性和训练稳定性。

摘要：蓄滞洪区的建设管理事关流域防洪安全、经济发展和生态化建设。在分析我国蓄滞洪区建设管理现状及存在问题的基础上,以PDCA循环改进策略(规划、实施、评估、改进)为理论基础,分别从防洪、经济、生态3个方面,针对目前蓄滞洪区防洪工程建设滞后、补偿机制不完善、生态化建设较少等问题展开研究,并结合蓄滞洪区协调发展的需求,提出蓄滞洪区防洪-经济-生态协调发展的改进方案。以东大圩蓄滞洪区为例,分析其发展现状及存在问题,基于建立的蓄滞洪区防洪-经济-生态协调发展水平评价指标体系,对PDCA循环改进后东大圩防洪-经济-生态协调发展水平进行评价,并从防洪、经济、生态3个方面提出了东大圩协调发展的综合保障措施。

摘要：Prosthesis implantation and fat transplantation are common breast *** general,prosthesis implantation alone does not achieve a realistic enough appearance,and fat transplantation alone is difficult to achieve in the correct *** date,no reports have focused on methods of combining fat with implanted prostheses for breast *** a newly designed bionic ink(i.e.,polyether F127 diacrylate(F127DA)&poly(ethylene glycol)diacrylate(PEGDA))and projection-based three-dimensional bioprinting(PBP),we report the development of a new method for printing porous *** was used to improve the printing precision of the prosthesis by increasing the gel point of F127DA and reducing the impact of external *** compression modulus of the printed prosthesis was very close to that of prostheses currently used in clinical practice and to that of natural ***,stromal vascular fraction gel(SVF-gel),a human fat extract,was injected into the pores of the synthesized prostheses to prepare a prosthesis mixed with adipose *** were implanted subcutaneously in nude mice to observe their biological *** 14 and 28 days of observation,the prosthesis showed good biocompatibility,and adipose tissues grew well in and around the *** result shows that a porous prosthesis containing pre-placed adipose tissues is a promising breast reconstruction material.

摘要：As surgical procedures transition from conventional resection to advanced tissue-regeneration technologies,human disease therapy has witnessed a great leap *** particular,three-dimensional(3D)bioprinting stands as a landmark in this setting,by promising the precise integration of biomaterials,cells,and bioactive molecules,thus opening up a novel avenue for tissue/organ *** by the editorial board of Bio-Design and Manufacturing,this review brings together a cohort of leading young scientists in China to dissect the core functionalities and evolutionary trajectory of 3D bioprinting,by elucidating the intricate challenges encountered in the manufacturing of transplantable *** further delve into the translational pathway from scientific research to clinical application,emphasizing the imperativeness of establishing a regulatory framework and rigorously enforcing quality-control ***,this review outlines the strategic landscape and innovative achievements of China in this field and provides a comprehensive roadmap for researchers worldwide to propel this field collectively to even greater heights.

摘要：有机共轭聚合物的载流子传输性能与共轭结构息息相关.然而,在分子水平上理解分子共轭长度与材料及器件性能的关系仍缺乏相关依据,设计和开发新型且共轭长度连续可控的结构单元在合成上面临挑战.基于此,本研究提供了一种新的分子设计和合成思路,通过氧化偶联的方式合成了一系列分子共轭长度可控的苯并二吲哚二酮衍生物的共轭低聚物,并将其构建成相应的聚合物,展示了其可调控的电子传输性能.随着中间构筑单元共轭长度的增加,材料的最低未占分子轨道(LUMO)能级逐渐降低,带隙变窄,传输性质由p型传输转变为双极型传输.含有单个苯并二吲哚二酮构筑单元的聚合物PBIDI-4F-T表现出了9.05×10^(-2) cm^(2)·V^(-1)·s^(-1)的最大电子迁移率和4.21×10^(-3) cm^(2)·V^(-1)·s^(-1)的最大空穴迁移率.本工作为探索电子受体低聚物单元共轭长度与聚合物载流子电荷传输性能之间的构效关系提供了新的参考.

摘要：分析长江口河势和潮滩冲淤发展变化 ,针对不同潮滩的冲淤稳定性 ,提出在冲刷河段因不同破坏因素而采用不同的保滩护岸方案 ,防止水土流失 ,稳固河势发展。从长江口非工程措施和工程措施 (围垦、保滩 )对长江口资源、环境和生态的正面和负面影响分析 ,提出保滩护岸。