Impacts of the unsaturation degree of long-chain fatty acids on the volatile fatty acid profiles of rumen microbial fermentation in goats in vitro

This study investigated the impacts of the degree of unsaturation （unsaturity） of long-chain fatty acids on volatile fatty acid （VFA） profiles of rumen fermentation in vitro. Six types of long-chain fatty acids, including stearic acid （C18：0, control group）, oleic acid （C18：1, n-9）, linoleic acid （C18：2, n-6）, a-linolenic acid （C18：3, n-3）, arachidonic acid （C20：4, n-6） and eicosapentaenoic acid （C20：5, n-3）, were tested. Rumen fluid from three goats fitted with ruminal fistulae was used as inoculum and the inclusion rate of long-chain fatty acid was at 3% （w/w） of substrate. Samples were taken for VFA analysis at 0, 3, 6, 9, 12, 18 and 24 h of incubation, respectively. The analysis showed that there were significant differences in the total VFA among treatments, sampling time points, and treatment×time point interactions （P〈0.01）. a-Linolenic acid had the highest total VFA （P〈0.01） among different long-chain fatty acids tested. The molar proportion of acetate in total VFA significantly differed among treatments （P〈0.01） and sampling time points （P〈0.01）, but not treatment×time point interactions （P〉0.05）. In contrast, the molar proportion of propionate did not differ among treatments during the whole incubation （P〉0.05）. However, for butyrate molar proportions, significant differences were found not only among sampling time points but also among treatments and treatment×time point interactions （P〈0.01）, with eicosapentaenoic acid having the highest value （P〈0.01）. Additionally, no statistically significant differences were found in the acetate to propionate ratios among treatments groups （P〉0.05）, even the treatments stearic acid and a-linolenic acid were numerically higher than the others. The inclusion of 3% long-chain unsaturated fatty acids differing in the degree of unsaturation brought out a significant quadratic regression relation between the total VFA concentration and the double bond number of fatty acid. In conclusion, the a-linolenic acid with 3 double bonds appeared better for improving rumen microbial fermentation and the total VFA concentration.

Vibration Reduction of Open-chain Flexible Manipulators by Optimizing Independent Motions of Branch Links

In order to suppress vibration in flexible manipulators, a new type of manipulator mechanism with controllable local degrees of freedom is proposed. This mechanism consists of a main chain and some branch links. The main chain is of a flexible open-chain configuration with an end-effector installed at its tip, and the rigid branch links are able to perform active movements. It is proved by kinematics and dynamic analysis that, the branch links bear no direct kinematic relation to the main chain, but their independent motions can strongly affect the dynamic behavior and performance of the flexible manipulator. Then comes a new idea of suppressing vibration, in which independent motions of the branch links are used to suppress the undesired vibration of the flexible main chain through dynamic coupling. On this basis, an optimal method for reducing vibration of flexible manipulators is proposed. Finally, the effectiveness of this method is verified by numerical simulations.

基于单根线棒连接的定子绕组设计及应用研究

对于特定转速的大型交流同步电机,通过单根线棒连接方式可以解决定子绕组极数与对称平衡支路数的匹配问题。本文分析了基于单根线棒连接方法的绕组对称性,提出了并联支路对称平衡的定量评估方法。并应用电磁场有限元分析和真机实测,验证了分析方法的有效性。

Using 2D NMR to determine the degree of branching of complicated hyperbranched polymers

Degree of branching (DB) is a crucial structure parameter of hyperbranched polymers, which can be determined by 1H NMR, quantitative 13C NMR, degradative method, etc. However, for complicated hy-perbranched polymers, intricate structure and severe overlap of spectral signals hinder the determina-tion of DB using traditional methods. In this work, the architecture of complicated hyperbranched polymers has been elucidated with the help of 2D NMR techniques. Using such a method, overlapped NMR signals can be well separated into a two-dimensional space, and additional structural information is also available. Correspondingly, quantitative analysis for complicated systems can be realized. De-termination of DBs for three types of complicated hyperbranched polymers synthesized from step-polymerization, self-condensation vinyl polymerization and self-condensation ring-opening po-lymerization is shown as examples.

A SYNTHETIC APPROACH FOR WATER SOLUBLE HYPERBRANCHED POLY(N,N-ETHYLIDENEBIS(N-2-CHLOROACETYL ACRYLAMIDE)) WITH HIGH DEGREE OF BRANCHING VIA ATOM TRANSFER RADICAL POLYMERIZATION/SELF-CONDENSING VINYL POLYMERIZATION

A novel acrylamide A2B2＊ （A = alkene, B＊ = alkyl chlorine） type inimer was obtained from commercially available 1,2-ethylenediamine, chloroacetyl chloride and acryloyl chloride. The as-prepared monomer can form water-soluble hyperbranched poly（N,N-ethylidene bis（N-2-chloroacetyl acrylamide））s （HPECA） through atom transfer radical polymerization/self-condensing vinyl polymerization method in the presence alkyl chlorine/CuCl/2,2-bipyridine activation system which can effectively suppress the gelation formation.1H-NMR spectra and dual detector size exclusion chromatography proved the hyperbranched structure indisputably, and the degree of branching was determined by the detailed analyses of 1H-NMR spectra. The trend of the degree of branching was in consistent with the result of Mark- Houwink exponent a. The experiment results suggested that the conversion was 67%, Mw = 13.2 x 104, Mark-Houwink a = 0.282 and the degree of branching = 64% when the reaction temperature was 120 ℃, reaction time = 168 h and N,N- ethylidene bis（N-2-chloroacetyl acrylamide）：Cu（I） = 50：0.62.

The weak density of properly d-r. e. branching degree in the d-r.e. degrees

It is proved that for any r.e. degreesv <u, there exists a properly d-r.e. degreec such thatc is a branching degree andv <c <u.

DEGREE OF BRANCHING OF THE HYPERBRANCHED POLYMERS RESULTED FROM AB_2 POLYCONDENSATION WITH SUBSTITUTION EFFECT

The analytical expressions of the various structural units and the average degree of branching for the hyperbranched polymers resulted from AB2 polycondensation with substitution effect were derived by the kinetic mechanism. The reactivity difference between the 13 group in linear unit and that in terminal group has great effect on the molecular parameters of the products obtained. The concentration of terminal units has a maximum with the increase of the conversion of A groups （x）. The higher the reactivity ratio （r） of linear B group to branched one is, the later the maximum appears and the larger it is. The degree of branching of the hyperbranched polymers obtained is controllable by adjusting the parameters of r and x, which increases with increasing both x and r.

ASYMPTOTIC BEHAVIOR OF SOLUTION BRANCHES OF NONLOCAL BOUNDARY VALUE PROBLEMS

In this article, by employing an oscillatory condition on the nonlinear term,a result is proved for the existence of connected component of solutions set of a nonlocal boundary value problem, which bifurcates from infinity and asymptotically oscillates over an interval of parameter values. An interesting and immediate consequence of such oscillation property of the connected component is the existence of infinitely many solutions of the nonlinear problem for all parameter values in that interval.

基于区块链的双分支结构扩展模型

随着区块链技术的迅速发展,区块链面临着存储开销和数据吞吐率方面的可扩展性挑战。受全体一致性共识原则影响,区块链节点需存储整个区块链的全局账本,数据存储开销大;同时,为维持区块内交易一致和可信,区块链网络中所有节点均需参与到交易验证同步中,导致网络中区块同步延迟高,带宽征用受阻,进一步降低了数据吞吐量。针对这些问题,提出了一种基于区块链的双分支结构扩展模型。首先,建立区块链三元存储扩展结构,节点对存储任务进行精准划分,分别存储区块链的单一、部分、全局账本,有效降低节点存储负担。其次,提出双分支结构模型,将主链进行信息分流,通过多通道子链并行存储数据,显著提升数据存储速率。针对分流后子链存在的兼容问题,引入双向轮换机制实现链式结构间融合过渡;针对分流后子链安全问题,提出赌徒扩展-F、赌徒扩展-S策略,对两种链式结构进行模拟安全攻击,并对攻击过程进行数学建模。最后,构建两个模型的安全性约束,验证双分支模型的安全性。实验结果表明,所提双分支结构扩展模型能有效抵御恶意双花攻击,且在存储开销、数据吞吐率方面有很大优势。

水热抽提玉米芯半纤维素结构变化及对酶解行为影响

为提高富含木聚糖的农业废弃物再利用-高效制备低聚木糖,该研究以玉米芯为原料,通过水热预处理结合乙醇分级沉淀获得不同组分半纤维素,并利用分子质量测定、糖基结构及红外表征了半纤维素组分的基本特征,研究了半纤维素结构变化及对酶解效果的影响。结果显示,当利用3倍体积的乙醇分离半纤维素时,木聚糖的得率达到最大为48.67%,醇沉获得的各木聚糖组分由木糖、葡萄糖、甘露糖等组成;分支度(木糖/阿拉伯糖)为6.61~16.10,木聚糖的沉淀主要受到木聚糖的分子质量和分支度2个因素的影响。以不同组分进行酶促反应动力学实验结果表明,分子质量分布系数较小同时分支度最小的组分,其K m及V max分别为(5.43±0.31)mg/mL和(154.9±2.33)U/mg,表现出的催化适应性明显高于其他组分,此结果显示分子质量及分支度可能是影响酶解效率的关键因素。

氢气在馏分油中溶解度的模拟研究

采用Aspen Plus软件建立了氢气在馏分油中溶解度的计算模型,对比分析了直馏汽油、柴油、蜡油、渣油4种馏分油中氢气溶解度随温度和压力的变化规律,进一步研究了馏分油中烃类组分的碳链长度、饱和度、结构对氢气溶解度的影响。实验结果表明,在馏分油中氢气的溶解度随压力的增加而增大;在一定温度范围内,馏分越重,氢气的溶解度越大;高温条件下氢气的溶解度受馏分油中环烷烃、芳烃等组分的影响;馏分油中烃类组分碳链越长、饱和度越高、支链越多,氢气的溶解度越大。

Outcomes in patients with COVID-19 and new onset heart blocks: Insight from the National Inpatient Sample database

BACKGROUND Coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in a worldwide health crisis since it first appeared.Numerous studies demonstrated the virus’s predilection to cardiomyocytes;however,the effects that COVID-19 has on the cardiac conduc-tion system still need to be fully understood.AIM To analyze the impact that COVID-19 has on the odds of major cardiovascular complications in patients with new onset heart blocks or bundle branch blocks(BBB).METHODS The 2020 National Inpatient Sample(NIS)database was used to identify patients admitted for COVID-19 pneumonia with and without high-degree atrioven-tricular blocks(HDAVB)and right or left BBB utilizing ICD-10 codes.The patients with pre-existing pacemakers,suggestive of a prior diagnosis of HDAVB or BBB,were excluded from the study.The primary outcome was inpatient mortality.Secondary outcomes included total hospital charges(THC),the length of hospital stay(LOS),and other major cardiac outcomes detailed in the Results section.Univariate and multivariate regression analyses were used to adjust for confounders with Stata version 17.RESULTS A total of 1058815 COVID-19 hospitalizations were identified within the 2020 NIS database,of which 3210(0.4%)and 17365(1.6%)patients were newly diagnosed with HDAVB and BBB,respectively.We observed a significantly higher odds of in-hospital mortality,cardiac arrest,cardiogenic shock,sepsis,arrythmias,and acute kidney injury in the COVID-19 and HDAVB group.There was no statistically significant difference in the odds of cerebral infarction or pulmonary embolism.Encounters with COVID-19 pneumonia and newly diagnosed BBB had a higher odds of arrythmias,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock than those without BBB.However,unlike HDAVB,COVID-19 pneumonia and BBB had no significant impact on mortality compared to patients without BBB.CONCLUSION In conclusion,there is a significantly higher odds of inpatient mortality,cardiac arrest,cardiogenic shock,sepsis,acute kidney injury,supraventricular tachycardia,ventricular tachycardia,THC,and LOS in patients with COVID-19 pneumonia and HDAVB as compared to patients without HDAVB.Likewise,patients with COVID-19 pneumonia in the BBB group similarly have a higher odds of supraventricular tachycardia,atrial fibrillation,atrial flutter,ventricular tachycardia,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock as compared to those without BBB.Therefore,it is essential for healthcare providers to be aware of the possible worse predicted outcomes that patients with new-onset HDAVB or BBB may experience following SARS-CoV-2 infection.

超支化聚合物作为分散剂的应用进展

简要介绍了超支化聚合物及其作为分散剂的主要原理,并对作为超支化聚合物关键性指标的支化度加以说明,针对其作为分散剂用途进行重点介绍,特别是在颜料和纳米材料中的应用前景。

基于极化分集的四单元三陷波超宽带天线设计

针对超宽带(UWB)系统中存在窄带信号干扰的问题,设计了一种四单元三陷波UWB天线。天线由4个水平正交放置的圆形贴片、微带馈线以及矩形接地板组成,通过在天线辐射贴片和微带馈线上刻蚀不同结构的几何缝隙实现了天线的三陷波特性。在介质基板背面添加十字形谐振枝节,有效提高了天线单元之间的隔离度。该天线尺寸为40 mm×40 mm×1.6 mm。实验结果表明:工作带宽为2~12 GHz,包络相关系数(ECC)小于0.02,分集增益(DG)大于9.92 dB,总有效反射系数(TARC)小于-2.38 dB,可广泛应用在UWB系统中。

聚醚破乳剂结构与压裂乳状液破乳效果的关系

以1,3-丙二醇、四乙烯五胺、聚酰胺-胺为起始剂合成了直链型、支链型及枝状聚醚破乳剂,采用瓶试法测定了这些破乳剂对模拟压裂乳状液的破乳效果,考察了破乳剂类型及分子结构对破乳效果的影响。结果表明,支链聚醚破乳剂的破乳效果优于直链聚醚破乳剂,且支化程度增加对破乳有利;以3.0代枝状聚酰胺-胺为起始剂的聚醚破乳剂破乳效果最好,当环氧乙烷与环氧丙烷的质量比(m(EO)/m(PO))为1/3、起始剂质量分数为0.5%时,制备的枝状聚醚破乳剂对模拟压裂乳状液7min即可完全破乳。

端丙烯酸酯基超支化聚(酯-胺)的结构分析及光固化

Aliphatic hyperbranched poly(ester amine)s with terminal acrylate groups were synthesized by Michael addition reaction between pizine and trimethylol propanetriacrylate (TMPTA) under various molar ratios, and their structures were characterized by 1H NMR,GPC and DSC analysis.The multi peaks within δ 4.04～4.18 (RCH 2OCOR′) in the 1H NMR spectra were analyzed and the peaks at δ 4.15, δ 4 06～4 07 and δ 4.04 can be assigned to terminal ( T ),linear ( L ) and dendritic units ( D ),respectively.Based on 1H NMR spectra,the degree of branching ( DB) for these polymers were calculated by using both the Fréchet method and the Frey method.With the molar ratio between pizine and TMPTA increased to 1/1,the terminate units decreased,both of the dendritic and linear units increased,while M n and M w/ M n became large and the T g value became high,accordingly.Moreover,cured films were obtained through UV radiation of the polymers.The gel contents for the films decreased with increasing the molar ratio between pizine and TMPTA,which may account for the changes of their mechanical properties.

支链数目和支链长度对梳形支化聚苯乙烯动态粘弹行为的影响

以主链长度相当、支链数目和支链长度依次变化的梳形支化聚苯乙烯为对象,使用平板式旋转流变仪测定其动态粘弹参数的温度谱和频率谱,研究了支链数目和支链长度对梳形支化聚苯乙烯动态粘弹行为的影响。结果表明,梳形支化聚苯乙烯的玻璃化转变温度高于相同相对分子质量范围的线型聚苯乙烯,而且随支链数目增加其玻璃化转变温度持续增大;梳形支化聚苯乙烯的粘流转变温度低于相同相对分子质量范围的线型聚苯乙烯,随支链长度增加,粘流转变温度和橡胶弹性平台区储能模量明显增大。与主链运动相对应的松弛过程发生在低频区,其特征松弛时间随支链数目增加明显延长,在更高频率下会出现与梳形支化聚苯乙烯的支链解缠结相关的支链松弛,随支链长度增加,支链特征松弛时间延长。

牡蛎糖原的研究(II)——牡蛎糖原的分子结构

本文应用酶法研究了牡蛎糖原的精细分子结构。结果显示牡蛎糖原的分子结构参数-平均链长,外链和内链平均长分别为13、9和3;用异淀粉酶和普鲁兰酶对牡蛎糖原的β-极限糊精进行顺序脱支,结果表明牡蛎糖原的A,B链比值为0.88:1.0,分支化度为1.88。

AB_g型缩聚形成的超支化聚合物的支化度与分子形态

用聚合反应动力学模型,详细分析了ABg型缩聚体系中各种结构单元的演变,对超支化聚合物支化度的各种定义作了比较,并对ABg型反应体系的支化度提出了一个改进的定义,使得支化度随g的增加而增加,当g从2增加到无穷大,最大支化度相应地从0.5增加到1-e-1.对均方回转半径的数值计算表明,在确定的A基团转化率(x),z-均均方回转半径几乎与g无关,当x=0.999时,随着g从2增加到无穷大,z-均回转半径只增加0.1%.但是,同样的条件下,z-均聚合度增加到2倍.这一现象表明在任何指定的A转化率,ABg型缩聚中形成的超支化聚合物的分子轮廓与g无关,随着g增大而在超支化聚合物中增加的结构单元(或聚合度)必定分布在分子内部.

高支化聚合物的合成与表征

介绍了近年来在高分子化学领域内十分活跃的高支化聚合物研究的状况。指出通过ＡＢｘ型单体的缩聚反应和Ａ＝Ｂ－Ｃ＊型单体的自缩合乙烯基聚合都可获得高支化聚合物。目前用以表征高支化聚合物支化度和分子量的方法主要为核磁共振法和凝胶渗透色谱法，在实际应用中都存在局限性。