基于梳状结构的复杂交联聚己内酯的合成及形状记忆行为

以正丁基锂为引发剂,通过活性阴离子聚合得到窄分布的聚丁二烯,然后通过环氧化和羟基化反应得到多羟基聚丁二烯。并以多羟基聚丁二烯作为大分子引发剂,通过开环聚合方法合成了梳状聚己内酯(gPCL),通过核磁共振波谱和凝胶渗透色谱测定结构信息,证明得到了分子量分布窄(PDI<1.18)的具有接枝结构的梳状聚己内酯。通过合成的梳状聚己内酯与六甲基二异氰酸酯(HDI)进行交联反应合成了一系列基于梳状结构的复杂交联聚己内酯(C-gPCL)。利用傅里叶变换红外光谱、差示扫描量热仪、广角X射线衍射、动态力学热分析仪、万能拉伸机等测试方法对获得的交联聚合物的性能进行了表征并对交联聚合物的形状记忆行为进行了分析。交联后的聚合物具有热致形状记忆效应,初始形变量为50%时,形状固定率可达99.6%,12 s即可回复形状且形状回复率可达98.8%;高支化结构的引入使得材料形状记忆效应更稳定,经过5次形状记忆过程循环后(单次形变量为50%),形状固定率仍达92.2%,形状回复率达93.6%。

红细胞分布宽度及血脂在肝硬化食管胃底静脉曲张破裂出血中的临床价值

目的探讨红细胞分布宽度(red cell distribution width,RDW)及血脂与肝硬化伴食管胃底静脉曲张破裂出血(gastroesophageal variceal bleeding,GEVB)的相关性及临床价值。方法以昆明市第三人民医院肝病综合科2021年1月至2021年5月期间收治住院的发生GEVB的肝硬化患者60例为出血组,随机选取同期住院的未发生GEVB的肝硬化患者60例为未出血组。对比分析2组患者的基本资料、RDW、PLT、肝功能生化指标和血脂相关指标,然后通过多因素二元Logistic回归分析探索RDW和血脂对GEVB的影响,最后用ROC曲线判断其诊断效能。结果与未出血组相比,出血组RDW升高,TG、TC、HDL-C、LDL-C、ApoA1、ApoE降低(均P<0.05)。二元Logistic回归分析提示,RDW是肝硬化患者发生GEVB的独立危险因素(OR=1.367,95%CI:1.141~1.639),TC是肝硬化患者发生GEVB的独立保护因素(OR=0.437,95%CI:0.262~0.728)(均P<0.05)。通过绘制ROC曲线提示,RDW诊断GEVB的曲线下面积(AUC)为0.803(P<0.05),最佳临界值15.25%,敏感度为86.7%、特异性为63.3%;TC诊断GEVB的AUC为0.789(P<0.05),最佳临界值2.765 mmol/L,敏感度为78.3%、特异性为75.0%。结论RDW及TC对于肝硬化患者发生GEVB具有较高的判断价值,临床需高度重视。

Regulation of Excited-State Intramolecular Proton Transfer Process and Photophysical Properties for Benzoxazole Isothiocyanate Fluorescent Dyes by Changing Atomic Electronegativity

Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativity of atoms on the ESIPT process and photophysical properties.Therefore,we selected a series of benzoxazole isothiocyanate fluorescent dyes(2-HOB,2-HSB,and 2-HSe B)by theoretical methods,and systematically studied the ESIPT process and photophysical properties by changing the electronegativity of chalcogen atoms.The calculated bond angle,bond length,energy gap,and infrared spectrum analysis show that the order of the strength of intramolecular hydrogen bonding of the three molecules is 2-HOB<2-HSB<2-HSe B.Correspondingly,the magnitude of the energy barrier of the potential energy curve is 2-HOB>2-HSB>2-HSe B.In addition,the calculated electronic spectrum shows that as the atomic electronegativity decreases,the emission spectrum has a redshift.Therefore,this work will offer certain theoretical guidance for the synthesis and application of new dyes based on ESIPT properties.

La_(2)O_(3)-modified BiYbO_(3)–Pb(Zr,Ti)O_(3) ternary piezoelectric ceramics with enhanced electrical properties and thermal depolarization temperature

High-performance Pb(Zr_(1−x)Ti_(x))O_(3)(PZT)piezoceramics are urgently desired by the market in view of their expanded operating temperature range,reduced property temperature dependence,and enhanced sensitivity and acoustic power.In this work,we reported a kind of low-cost and high-performance 0.06BiYbO_(3)–0.94Pb(Zr_(0.48)Ti_(0.52))O_(3) ternary piezoceramics;the modifying effects of La_(2)O_(3) on this perovskite system were investigated in terms of the structures,electrical properties,and thermal depolarization behaviors of ceramics.The field-dependent dielectric and conduction properties indicated that there are close correlations among oxygen vacancies(VO),conducting electrons,and intrinsic conduction process.The degradation in ferroelectric properties observed in those samples doped with more than 0.15 wt%of La_(2)O_(3) indicated that the occupying mechanisms of La^(3+)changed from the donor substitution for Pb^(2+)to the isovalent substitution for Bi^(3+).The thermally depoling micromechanisms of ceramics were revealed from the thermodynamic processes of defect dipoles and intrinsic dipoles within ferroelectric domains.The sample doped with 0.15 wt%of La_(2)O_(3) shows excellent electrical properties with TC=387℃,d33=332 pC/N,TKε=5.81×10^(−3)℃−1,Pr=20.66μC/cm^(2),Td=356℃.The significantly enhanced electrical properties and thermal depolarization temperature benefited from the donor substitution of La3+,decreasing the oxygen vacancy concentration in the lattice and possibly optimizing the ferroelectric domain structure of ceramics.

An Emergency Shelter Location Model Based on the Sense of Security and the Reliability Level

Based on the value function of the prospect theory,this paper constructs a security function,which is used to describe the victims’feelings about the distance in emergency evacuation.Since different paths between the demand points and the emergency shelters are generally of different importance degrees,they are divided into main paths and auxiliary paths.The security function values and the reliability levels of main paths and auxiliary paths are given different weights.The weighted sum of the security function values and the weighted sum of the reliability level function values of all demand points are maximized to determine the location and the number of the emergency shelters,the transfer paths,the reinforced edges and the incremental reliability level of the selected edge.In order to solve the model,a two-stage simulated annealing-particle swarm optimization algorithm is proposed.In this algorithm,the particle swarm optimization(PSO)algorithm is embedded into the simulated annealing(SA)algorithm.The cumulative probability operator and the cost probability operator are formed to determine the evolution of the particles.Considering the budget constraint,the algorithm eliminates the shelter combinations that do not meet the constraint,which greatly saves the calculation time and improves the efficiency.The proposed algorithm is applied to a case,which verifies its feasibility and stability.The model and the algorithm of this paper provide a basis for emergency management departments to make the earthquake emergency planning.

Effect of the electro-acupuncture on senile plaques and its formation in APPD/PS1D double transgenic mice

Alzheimer’s disease(AD)is a progressive neurodegenerative disease and its incidence will increase with age and is aggravating.The senile plaques(SPs)are one of three main pathological features in AD patients,which are formed by amyloid b-protein(Ab)overaccumulation.b-amyloid precursor protein(APP),b-site APP cleavage(BACE1),and insulin degrading enzyme(IDE)proteins participate in the process of Ab production and degradation.At present,the pathogenesis of AD is not yet clear and the current treatment methods can only relief the related symptoms of AD.The electro-acupuncture(EA)is a traditional Chinese medicine treatment combined the acupuncture and electrical stimulation and the treatment effect can also be controlled by transform the electrical frequency.Thus,in this experiment,we carried out behavioral test,immunohistochemistry(IHC),and Western Blot(WB)after different period treatments to the model mice by electro-acupuncturing“Baihui”and“Shenshu”acupoints in APPt/PS1t double transgenic mice.It was found that the EA therapy can improve the ability of learning,memory and spatial exploration,and reduce the deposition of SPs in brain of AD model mice,and reduce the expressions of APP and BACE1,increase the expression of IDE protein.These results prompt that EA can effectively alleviate the pathological process of AD.We speculate that EA may play a comprehensive role in preventing the development of AD,considering the previous data.