Molecular insights into the ‘defects’ network in the thermosets and the influence on the mechanical performance

The introduction of ‘defects’ to the thermoset crosslinking network is one of the most applicable strategies for improving the modulus and toughness simultaneously. However, the reinforcement effect disappears when the ‘defects’ proportion exceeds the threshold. The speculated mechanism was that the aggregation and entanglement of the ‘defects’ chains changed the matrix topology, making the stacking structure more compact. However, the ‘defects’ are hardly directly observed in the experiment. As the result, the relationship between the ‘defects’ proportion and the package state of the matrix, and the effect on the material''s mechanical performance was not explored. Herein, the network of bisphenol-A diglycidyl (DGEBA) with diethyltoluenediamine (DETDA) as the hardener was constructed using MD simulation, and n-butylamine was decorated on the matrix by replacing a proportion of DETDA acting as the ‘defects’. The results indicated that the aliphatic chains aggregated and entangled at a low concentration, occupying the voids in the rigid aromatic crosslinking structure, thus lowering the free volume. The strong non-bonding interactions drew the matrix segments close together, thus reinforcing the resin. However, the microphases formed by the aliphatic chains no longer filled the voids but created a new free volume and loosened the network when the content increased, which reduced the mechanical performance of the material. The experimental results were consistent with the findings in the simulations. The moduli of the resin increased with the increase in the n-butylamine content first and then declined. The maximum moduli of the thermosets was 3.4 GPa in S₃₀, which was about 25% higher compared with the control; the corresponding elongation at break was 8.9%, which was about 46% improved compared with the control.

The introduction of ‘defects’ to the thermoset crosslinking network is one of the most applicable strategies for improving the modulus and toughness simultaneously.     

Improved nitrogen reduction activity of NbSe2 tuned by edge chirality

Efficient catalysts for the electroreduction of N₂ to NH₃ are of paramount importance for sustainable ammonia production. Recently, it was reported that NbSe₂ nanosheets exhibit an excellent catalytic activity for nitrogen reduction under ambient conditions. However, existing theoretical calculations suggested an overpotential over 3.0 V, which is too high to interpret the experimental observations. To reveal the underlying mechanism of the high catalytic activity, in this work, we assessed NbSe₂ edges with different chirality and Se vacancies by using first principles calculations. Our results show that N₂ can be efficiently reduced to NH₃ on a pristine zigzag edge via the enzymatic pathway with an overpotential of 0.45 V. Electronic structure analysis demonstrates that the N₂ molecule is activated by the back-donation mechanism. The efficient tuning of the local chemical environments by edge chirality provides a promising approach for catalyst design.

The zigzag edge of the NbSe₂ monolayer exhibits an overpotential as low as 0.45 V along the enzymatic pathway.     

A novel robust nomogram based on peripheral monocyte counts for predicting lymph node metastasis of prostate cancer

Accurate methods for identifying pelvic lymph node metastasis(LNM)of prostate cancer(PCa)prior to surgery are still lacking.We aimed to investigate the predicti...     

新型冠状病毒感染相关急性黄斑区神经视网膜病变的神经眼科特征

目的：总结新型冠状病毒(SARS-CoV-2)感染相关急性黄斑区神经视网膜病变(AMN)的神经眼科特征。

方法：纳入2022-12-27/2023-02-01就诊于西安市第一医院(西北大学附属第一医院)神经眼科并经相关检查确诊为AMN的患者8例(6例女性,2例男性)共14眼纳入本次研究。所有患者病前均有SARS-CoV-2感染史。收集患者的临床资料。纳入最佳矫正视力(BCVA)、非接触间接眼压测定、眼底彩色照相、近红外成像(IR)、频域光学相干断层扫描(SD-OCT)、OCT血流成像(OCTA)、眼底荧光素血管造影(FFA)、吲哚菁绿血管造影(ICGA)、视野、视觉诱发电位(VEP)和视网膜电流图(ERG)检查结果。对纳入患者的神经眼科特征进行分析总结。

结果：纳入的8例患者年龄20-43(平均30±6.63)岁。病前3-11(平均5±3.51)d有SARS-CoV-2感染史,8例患者中有6例在感染SARS-CoV-2的5 d内出现视觉症状。患者的临床表现为视力下降或视物遮挡感; 纳入患者的视力0.08-1.0; 视野缺损表现为中心、旁中心暗点或合并周边暗点。VEP可见P100或P2峰时延迟; ERG提示视网膜感光细胞 功能受损。在疾病早期,SARS-CoV-2感染相关AMN患者可能存在视力、视野和视网膜外层病变大小及形状可能不匹配的情况,并发现视力越低,VEP峰时越迟。

结论：除眼底多模影像,SARS-CoV-2感染相关AMN的神经眼科特征需要临床医师关注,视功能及电生理可以辅助临床更加全面评估患者及判断预后。     

不同公式计算角膜屈光术后白内障患者IOL屈光度的准确性比较

目的：对比观察5种人工晶状体(IOL)计算公式在角膜屈光术后白内障患者IOL屈光度计算中的准确性。

方法：前瞻性系列病例研究。收集2021-09/2023-03就诊于济南明水眼科医院的既往行角膜屈光手术矫正近视的白内障患者23例34眼,其中准分子角膜切削术(PRK)手术史1例1眼,准分子原位角膜磨镶术(LASIK)术后22例33眼。白内障术前采用IOL Master 700测量眼生物学参数; Pentacam眼前节分析系统测量角膜真实净屈光力(TNP); 眼前节OCT测量净角膜屈光力(NCP)、角膜后表面屈光力、角膜厚度(CCT)。采用Shammas公式、Haigis-L公式、Potvin-Hill Pentacam公式、OCT公式、Barrett True K公式进行IOL度数计算后综合选择合适的IOL度数。术后1 mo在客观验光的基础上行主觉验光获得术后实际屈光状态,根据术后验光结果计算5种公式的屈光预测误差(RPE),其绝对值为屈光绝对误差(RAE),比较RPE与0的差异及不同公式间RPE、RAE的差异,并统计RAE≤0.5 D、≤1.0 D的眼数所占百分比。

结果：5种公式计算所得的RPE与0比较均无差异(均P>0.05)。5种计算公式的RPE、RAE整体无差异(F=0.554,P=0.696; H=4.402,P=0.354); Potvin-Hill Pentacam公式、Barrett True K公式的RAE在≤0.5 D内的眼占比分别为26眼(76%)、24眼(71%),在≤1.0 D内的眼占比均为33眼(97%)。

结论：Barrett True K 公式、Potvin-Hill Pentacam公式在角膜屈光术后白内障患者IOL屈光度计算中表现出较高的预测性。由于此类人群角膜屈光力存在差异,IOL度数计算问题仍需要进一步研究,临床上建议多种公式综合考虑。     

化疗栓塞与化疗灌注在中晚期膀胱癌治疗中的对照研究

目的采用生存分析的方法对照研究化疗栓塞与化疗灌注在中、晚期膀胱癌中的治疗作用。资料与方法69例中、晚期膀胱癌患者分为两组,一组行双侧髂内动脉化疗灌注术,另一组行双侧髂内动脉化疗栓塞术。应用Cox比例风险模型对各个因素与术后膀胱癌的生存时间进行回归分析,筛选出主要的影响因素;应用Kaplan-Meier生存曲线分析两种治疗方法与生存时间的关系,并进行Log-Rank检验。结果69例手术均成功,双侧髂内动脉化疗栓塞术组生存时间为5~52个月,平均(26.52±3.29)个月;双侧髂内动脉化疗灌注术组生存时间为4~36个月,平均(13.41±1.69)个月。中晚期膀胱癌的死亡率与介入治疗的两种方法的相关性差异有统计学意义(P<0.05),其风险度为3.220,回归系数为1.169,证明双侧髂内动脉化疗栓塞术对于提高患者的生存时间具有更重要的意义。接受双侧髂内动脉化疗栓塞术的患者,生存时间明显高于接受双侧髂内动脉化疗灌注术的患者。结论应用化疗栓塞治疗较单纯化疗灌注治疗可明显提高患者的生存时间。     

肝癌组织中p27蛋白表达与肿瘤增殖凋亡活性的研究

研究肝细胞癌组织中p27表达对细胞增殖与凋亡活性的影响.采用Elivision法检测47例肝癌及相应癌旁肝组织中p27及PCNA的表达,TUNEL法检测原位细胞凋亡.结果显示肝癌组织中细胞增殖与凋亡指数明显高于癌旁肝组织.肝癌组织中p27染色指数明显低于癌旁肝组织与正常肝组织.低分化肝癌组织中p27表达和凋亡指数均明显降低.存在肝外转移的肝癌组织中p27表达降低而增殖指数明显增高.进一步研究显示,p27高表达组肝癌组织中凋亡指数明显高于低表达组,而增殖指数却显著降低.提示p27蛋白表达降低与肝癌的发生和进展有着密切关系,并可能是导致肝癌细胞增殖凋亡失衡的因素之一.     

基于医务人员视角的远程医疗服务使用意愿和关键问题研究

目的:分析我国医务人员远程医疗服务使用意愿和关键问题,以完善远程医疗服务体系。方法:2019年10—11月,对福建、海南、河南、湖南、贵州、四川和青海7个省份中已参与过远程医疗的邀请方和受邀方医务人员进行电子问卷调查,主要内容为医务人员对远程医疗的使用意愿、满意度情况和认知评价情况等。通过描述性统计分析和非参数检验,探...     

多系统萎缩的临床特征与疾病进展的特点

目的探讨多系统萎缩(MSA)的临床特征与疾病进展的特点。方法回顾性分析28例拟诊MSA患者的临床资料;用代表日常生活活动能力(ADL)的3个重要事件(辅助行走、依靠轮椅、卧床状态)对疾病进展进行评估;通过Kaplan-Meier曲线分析各亚组间的差异。结果3个以上系统受累26例(92.9%),普遍存在自主神经功能障碍。从起病进展为临床MSA平均2年;进展为辅助行走、依靠轮椅和卧床状态分别为3年、5年、7年。运动和自主神经系统同时受累的患者起病3年内疾病进展的危险性明显增加(P<0.01)。结论MSA是一种多系统受累的慢性进展性疾病,从起始症状到同时出现运动和自主神经功能障碍的间隔时间能够预测MSA功能衰退的进展。