丁腈橡胶/低聚合度聚氯乙烯共混胶性能的研究

采用机械共混法制备中高丙烯腈含量丁腈橡胶(NBR)/低聚合度聚氯乙烯(PVC)共混胶,研究NBR/PVC共混比和增塑剂DOTP用量对NBR/PVC共混胶性能的影响。结果表明:与NBR胶料相比,NBR/PVC共混胶的t_(90)显著延长;随着PVC用量的增大,NBR/PVC共混胶的t_(10)延长,交联密度降低,定伸应力提高,拉伸强度和拉断伸长率先提高后降低,损耗峰向高温方向移动,玻璃化温度升高,在室温下的阻尼性能明显改善;NBR与PVC以不同共混比共混均可得到均相体系;随着增塑剂DOTP用量的增大,NBR/PVC共混胶的t_(10)和t_(90)呈延长趋势,硫化速度呈减慢趋势,交联密度、物理性能和阻尼性能降低。

不同聚合度魔芋葡甘低聚糖的酶解制备及其体外益生功能

以魔芋葡甘聚糖(konjac glucomannan,KGM)为原料,研究β-甘露聚糖酶酶解后魔芋葡甘低聚糖(konjac oligoglucomannan,KOGM)的制备流程对聚合度(polymerization degree,DP)的影响,探讨不同聚合度KOGM与原料KGM在理化性质、微观结构上的差异以及对5种乳酸菌的增殖、产酸、总糖利用及短链脂肪酸的影响。结果表明,采用酵母发酵去除单糖以及随后的离心和灭菌工艺对KOGM聚合度无明显影响。制备得到的3种KOGM的聚合度分别为16.74、12.74和11.13。3种KOGM与原料KGM具有相似的主链结构,其中2种低聚合度KOGM(low polymerization konjac oligoglucomannan,KOGM-L)(KOGM-L_(1)的DP为12.74,KOGM-L_(2)的DP为11.13)有更低的黏度特征,且存在相似的微观形态,呈现更加明显的碎片化和孔洞结构。与KGM和中聚合度KOGM(medium polymerization konjac oligoglucomannan,KOGM-M)(DP为16.74)相比,低聚合度KOGM-L更有利于促进乳酸菌增殖、产酸及总糖分解,但2种低聚合度KOGM-L之间没有显著差异(P>0.05)。低聚合度KOGM-L_(2)与长双歧杆菌培养时总菌数最高(OD_(600)=2.13),但是低聚合度KOGM-L_(1)与鼠李糖乳杆菌培养时增殖倍数最高(4~5倍)。短链脂肪酸总产量及各组分含量显示低聚合度KOGM-L要显著高于中聚合度KOGM-M、原料KGM和菊糖(P<0.05)。综上所述,不同聚合度的KOGM益生功能差异明显,低聚合度KOGM效果最佳。聚合度相近的KOGM益生功能相似,聚合度11~13对长双歧杆菌和鼠李糖乳杆菌有更好的益生效果。

Modifications in aroma characteristics of'Merlot'dry red wines aged in American,French and Slovakian oak barrels with different toasting degrees

Aging in oak barrels is widely used in enology which could bring flavor changes and aromatic complexity to wines.In the present study,the aroma compounds were analyzed from the‘Merlot’dry red wines,which were fermented in two types of fermenters(stainless steel tank and rotated oak barrel)and aged in six types of oak barrels(three geographic origins×two toasting degrees)for different time(0,3,6 and 9 months,respectively).Results showed that 30 volatiles were associated with barrels and increased during oak aging.The fermenters could influence the intensities of the toast,leathery,smoky,fruity,floral and caramel aromas.The concentration of whisky lactone,eugenol,cis-isoeugenol,and the intensities of the toast and spicy aromas were highest in the wines aged in American oak and were lowest in the wines aged in French oak barrels.The concentrations of guaiacol,syringol,trans-isoeugenol,furfural alcohol,vanilla,cis-whisky lactone enabled the medium toasting barrels to be distinguished from the light toasting ones.The compounds originating from the barrels could be used to distinguish the types of different barrels,but the other general grape-derived and fermentation-derived volatiles could not.The fermenters,oak species and toasting degrees of the barrels all had significant effects on the aroma profiles of the aged‘Merlot’dry red wines,but the influence of the geographic origin was not obvious.

Research on Condenser Deterioration Evolution Trend Based on ANP-EWM Fusion Health Degree

This study presents a proposed method for assessing the condition and predicting the future status of condensers operating in seawater over an extended period.The aim is to address the problems of scaling and corrosion,which lead to increased loss of cold resources.The method involves utilising a set of multivariate feature parameters associated with the condenser as input for evaluation and trend prediction.This methodology offers a precise means of determining the optimal timing for condenser cleaning,with the ultimate goal of improving its overall performance.The proposed approach involves the integration of the analytic network process with subjective expert experience and the entropy weightmethod with objective big data analysis to develop a fusion health degreemodel.The mathematical model is constructed quantitatively using the improved Mahalanobis distance.Furthermore,a comprehensive prediction model is developed by integrating the improved Informer model and Markov error correction.This model takes into account the health status of the equipment and several influencing factors,includingmultivariate feature characteristics.This model facilitates the objective examination and prediction of the progression of equipment deterioration trends.The present study involves the computation and verification of the field time series data,which serves to demonstrate the accuracy of the condenser health-related models proposed in this research.These models effectively depict the real condition and temporal variations of the equipment,thus offering a valuable method for determining the precise cleaning time required for the condenser.

Modelling rapid non-destructive test using light weight deflectometer on granular soils across different degrees of saturation

This study introduces an advanced finite element model for the light weight deflectometer(LWD),which integrates contact mechanics with fully coupled models.By simulating LWD tests on granular soils at various saturation levels,the model accurately reflects the dependence of the LWD modulus on dry density,water content,and effective stress.This model addresses and overcomes the limitations of previous finite element models for this specific problem.Simultaneously,this research presents the first experimentally validated fully coupled contact impact model.Furthermore,the research provides a comparative assessment of elastoplastic and nonlinear elastic models and contrasts an enriched node-tosegment method(developed in this study)with the more precise mortar technique for contact mechanics.These comparisons reveal unique advantages and challenges for each method.Moreover,the study underscores the importance of careful application of the LWD modulus,emphasising the need for sophisticated tools to interpret soil behaviour accurately.

Wellbore Cleaning Degree and Hydraulic Extension in Shale Oil Horizontal Wells

The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investigated experimentallyby focusing on the dimensionless cuttings bed height. A method is proposed to calculate the horizontalwellhydraulic extension taking into account the influence of the wellbore cleaning degree on the wellborepressure distribution and assess the effect of a variety of factors such as the bottom hole pressure, the circulatingpressure drop, the drilling pump performance and the formation properties. The analysis shows that the hydraulicextension of horizontal wells decreases with an increase in the cuttings bed height, and the higher the displacementof drilling fluid, the faster the hydraulic extension declines. The annular pressure drop of the horizontalsection increases with the increase of the cuttings bed height, resulting in a higher bottom-hole pressure. Severalarguments are provided to guide the safe drilling of shale oil horizontal wells and overcome the limits of currenttechnological approaches.

邻苯二甲酸二烯丙基酯在高聚合度PVC树脂生产中的应用

以VCM为第一单体、邻苯二甲酸二烯丙基酯(DAP)为第二单体,将聚合反应温度控制在53℃,研究了DAP的添加量对PVC聚合度的影响。结果表明,随着DAP用量的增加,PVC的平均聚合度提高。

全瓷冠预备体轴面聚合度的测量与分析

目的:本研究比较了修复教学医生、修复专科医生、全科医生的前牙、前磨牙、磨牙全瓷冠牙体预备的预备体轴面聚合度。方法:从就诊的患者中筛选符合纳入标准的256个全瓷冠预备体的数据。按照牙位分3组:前牙、前磨牙、磨牙。17名口腔医生按照专业分成三组:修复教学组、修复专科组、全科组。测量预备体近远中及唇舌向的轴面聚合度,以及分析在同组医生中不同组牙位的全瓷冠预备体的轴面聚合度差异以及在同组牙位中不同组医生的全瓷冠预备体轴面聚合度的差异。结果:预备体轴面聚合度最大值在各个医生组中都存在于磨牙组。所有牙位的轴面聚合度均数均大于理论值(小于6°)。全科组的磨牙近远中向轴面聚合度最大(26.11±12.23°),修复专科组的前牙近远中向轴面聚合度最小(6.58±3.83°)。在每组医生中不同组牙位的唇舌向轴面聚合度(FL)及近远中向轴面聚合度(MD)的差异均具有统计学意义(P<0.05),在前磨牙组中不同组医生的预备体轴面聚合度的差异均具有统计学意义(P<0.05)。结论:数字化软件是测量预备体几何形状的有用工具。全瓷冠预备体的轴面聚合度对口腔医生有很高的要求,理论上推荐的值在临床中很少能达到,特别是磨牙。

超低聚合度PVC树脂的生产现状与发展趋势

介绍了超低聚合度PVC的制备方法,总结了国内外应用链转移剂法制备超低聚合度PVC树脂的研究进展,阐述了超低聚合度PVC在合金材料、塑料添加剂和油墨领域的应用情况。

紫象草原花青素的大孔吸附树脂纯化、平均聚合度及体外抗氧化活性测定

试验旨在利用大孔吸附树脂获得紫象草原花青素粗提物的纯化条件,并探究在此条件下获得纯化物的平均聚合度和体外抗氧化活性。试验采用单因素试验设计,通过比较3种大孔吸附树脂D101、HP-20、ADS-17的吸附与解吸特性,选择最优吸附树脂类型,对紫象草原花青素粗提物进行洗脱浓度、上样体积和洗脱体积的筛选,之后利用静态和动态吸附与解吸试验确定纯化条件,制备紫象草原花青素纯化物;采用盐酸-香草醛法测定纯化物原花青素的平均聚合度及其对1,1-二苯基-2三硝基肼(DPPH·)和羟自由基(·OH)的体外清除率。结果表明:采用φ2.6 cm×30.0 cm玻璃层析柱,选择D101型大孔吸附树脂、90%(V/V)浓度乙醇为洗脱剂,上样体积480 mL,洗脱体积155 mL时纯化效果较好,纯化后原花青素B2含量由纯化前10.01 mg/g提升至13.82 mg/g,提升了36.06%;紫象草原花青素粗提物经乙酸乙酯萃取后,获得水相和乙酸乙酯相的平均聚合度分别为26.87、13.63,纯化物的平均聚合度为14.67。当紫象草原花青素纯化物质量浓度为100 mg/mL时,DPPH·、·OH清除能力分别为99.55%、97.72%,相当于1 mg/mL维生素C,并且紫象草原花青素纯化物体外抗氧化活性显著高于粗提物(P<0.05)。综上所述,试验获得了大孔吸附树脂纯化紫象草原花青素的条件,纯化处理基本不影响原花青素提取物的平均聚合度,并发现原花青素纯化物具有良好的体外抗氧化活性。

悬浮法低聚合度聚氯乙烯树脂的孔隙调控

研究了主分散剂、辅助分散剂、链转移剂的种类和用量对低聚合度聚氯乙烯树脂孔隙率的影响规律,对比了采用恒温聚合和变温聚合工艺制备的低聚合度聚氯乙烯树脂的性能。结果表明,采用较低醇解度的聚氯乙烯醇和羟丙基甲基纤维素作为主分散剂,再加入一定量的辅助分散剂可以提升孔隙结构;变温聚合工艺和链转移剂的加入均能提升孔隙率。

Triad-displaced ULAs configuration for non-circular sources with larger continuous virtual aperture and enhanced degrees of freedom

Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation accuracy.However,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for NCS.The TdisULAs structure generally consists of three ULAs,which are appropriately placed.The proposed antenna array approach fully exploits the non-circular characteristics of the sources.Given the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors.Advantageously,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form expressions.Moreover,the proposed array also produces a filled resulting co-array.Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.

Degree of Freedom Analysis for Holographic MIMO Based on a Mutual-Coupling-Compliant Channel Model

Degree of freedom(DOF)is a key indicator for spatial multiplexing layers of a wireless channel.Traditionally,the channel of a multiple-input multiple-output(MIMO)half-wavelength dipole array has a DOF that equals the antenna number.However,recent studies suggest that the DOF could be less than the antenna number when strong mutual coupling is considered.We utilize a mutual-coupling-compliant channel model to investigate the DOF of the holographic MIMO(HMIMO)channel and give a upper bound of the DOF with strong mutual coupling.Our numerical simulations demonstrate that a dense array can support more DOF per unit aperture as compared with a half-wavelength MIMO system.

新疆天业天伟化工厂成功研发低聚合度聚氯乙烯专用树脂

2024年2月,新疆天业天伟化工有限公司化工厂(以下简称“天伟化工厂”)宣布成功研发出一种低聚合度聚氯乙烯专用树脂,并已顺利实现产品下线。这一突破不仅彰显了天伟化工厂在技术创新方面的坚定决心,也标志着该厂在特种树脂领域迈出了重要的一步。

Probability Distribution of China Aviation Network Average Degree of Edge Vertices and Its Evolutionary Trace Based on Complex Network

In order to reveal the complex network characteristics and evolution principle of China aviation network, the probability distribution and evolution trace of average degree of edge vertices of China aviation network were studied based on the statistics data of China civil aviation network in 1988, 1994, 2001, 2008 and 2015. According to the theory and method of complex network, the network system was constructed with the city where the airport was located as the network node and the route between cities as the edge of the network. Based on the statistical data, the average degrees of edge vertices in China aviation network in 1988, 1994, 2001, 2008 and 2015 were calculated. Using the probability statistical analysis method and regression analysis approach, it was found that the average degree of edge vertices had the probability distribution of normal function and the position parameters and scale parameters of the probability distribution had linear evolution trace.

Nonlinear Relationship and Its Evolutionary Trace between Node Degree and Average Path Length of China Aviation Network Based on Complex Network

In order to reveal the complex network characteristics and evolution principle of China aviation network,the relationship between the node degree and the average path length of China aviation network in 1988,1994,2001,2008 and 2015 was studied.According to the theory and method of complex network,the network system was constructed with the city where the airport was located as the network node and the airline as the edge of the network.On the basis of the statistical data,the node average path length of China aviation network in 1988,1994,2001,2008 and 2015 was calculated.Through regression analysis,it was found that the node degree had a logarithmic relationship with the average length of node path,and the two parameters of the logarithmic relationship had linear evolutionary trace.Key word:China aviation network,complex network,node degree,average length of node path,logarithmic relationship,evolutionary trace.

Probability Distribution of Ratio of China Aviation Network Edge Vertices Degree and Its Evolutionary Trace Based on Complex Network

In order to reveal the complex network characteristics and evolution principle of China aviation network, the probability distribution and evolution trace of ratio of China aviation network edge vertices degree were studied based on the statistics data of China civil aviation network in 1988, 1994, 2001, 2008 and 2015. According to the theory and method of complex network, the network system was constructed with the city where the airport was located as the network node and the route between cities as the edge of the network. Based on the statistical data, the ratio of edge vertices degree in China aviation network in 1988, 1994, 2001, 2008 and 2015 were calculated. Using the probability statistical analysis method and regression analysis approach, it was found that the ratio of edge vertices degree had linear probability distribution and the two parameters of the probability distribution had linear evolution trace.

Probability Distribution of Arithmetic Average of China Aviation Network Edge Vertices Nearest Neighbor Average Degree Value and Its Evolutionary Trace Based on Complex Network

In order to reveal the complex network characteristics and evolution principle of China aviation network,the probability distribution and evolution trace of arithmetic average of edge vertices nearest neighbor average degree values of China aviation network were studied based on the statistics data of China civil aviation network in 1988,1994,2001,2008 and 2015.According to the theory and method of complex network,the network system was constructed with the city where the airport was located as the network node and the route between cities as the edge of the network.Based on the statistical data,the arithmetic averages of edge vertices nearest neighbor average degree values of China aviation network in 1988,1994,2001,2008 and 2015 were calculated.Using the probability statistical analysis method,it was found that the arithmetic average of edge vertices nearest neighbor average degree values had the probability distribution of normal function and the position parameters and scale parameters of the probability distribution had linear evolution trace.

不同聚合度壳寡糖单体在小鼠体内的吸收分布

荧光探针标记操作简单且荧光的检测灵敏度比紫外-可见光谱等传统方法高3~4个数量级,故本实验借助荧光探针测定并分析不同聚合度壳寡糖单体在小鼠体内的吸收分布。制备异硫氰酸荧光素标记的壳寡糖单体并灌胃小鼠,借助小动物活体光学成像系统和荧光定量检测,分析聚合度2~5的壳寡糖单体在小鼠体内吸收分布的差异性。结果显示,荧光标记的壳寡糖单体灌胃小鼠1 h后,在小鼠体内的荧光信号达到最大分布,壳寡糖能吸收入血,并跨过血脑屏障分布到脑组织中,主要分布在肾和肝脏中,其次分布在心和脾,少量分布在肺和脑;不同聚合度壳寡糖单体在肾和肝的分布量与聚合度呈正相关,而在血清、心、脾、肺和脑中的峰值分布量为壳二糖最多,壳四糖其次,壳五糖最少。明确不同聚合度壳寡糖单体的体内吸收分布的差异性,对于壳寡糖功能活性的构效关系研究具有一定的指导意义,能为壳寡糖的功能活性机制研究以及加快壳寡糖在食品功能性食品的开发和应用提供参考。

高聚合度菊粉通过调节肠-脂肪组织轴改善高脂饮食诱导的犬肥胖

旨在基于肠-脂肪组织轴研究高聚合度菊粉改善高脂饮食诱导犬肥胖的作用机制。试验选取40只贵宾犬,随机等分为5组:正常饲粮组、高脂饲粮组和高聚合度菊粉低剂量组、中剂量组及高剂量组。正常饲粮组饲喂正常饲粮,高脂饲粮组饲喂高脂饲粮,高聚合度菊粉低剂量组、中剂量组及高剂量组分别饲喂含1.0%、3.0%和5.0%高聚合度菊粉的高脂饲粮,试验期为12周。试验结束后,测定血清糖脂和炎症因子含量,分别用实时荧光PCR检测和Western blot检测皮下脂肪组织和结肠黏膜中相关因子的mRNA相对表达和蛋白相对表达。结果表明:高聚合度菊粉可有效降低高脂饮食犬的体重、体脂率和血脂水平,改善糖耐量受损,提高结肠黏膜中闭锁蛋白(Occludin)和闭锁小带蛋白-1(ZO-1)的mRNA与蛋白表达量,降低血清脂多糖(LPS)、IL-6和TNF-ɑ水平以及脂肪组织中IL-6和TNF-ɑ蛋白表达。综上所述,高聚合度菊粉对高脂饮食诱导犬肥胖具有改善作用,其作用机制可能与调节“肠黏膜屏障功能-LPS易位-脂肪组织炎症”这一肠-脂肪组织轴有关。