Effect of salt solutions on chain structure of partially hydrolyzed polyacrylamide

The effect of salt solutions(NaCl,Na2SO4 and CaCl2) on the conformational properties of partially hydrolyzed polyacrylamide(HPAM) was investigated by using static laser light scattering(SLLS).The special interaction between CaCl2 solution and HPAM was also researched.Experimental results show that the chain structure of HPAM is interrelated with the charge density,the kind and the concentration of salt solutions.The mean-square radius of gyration(Rz) and the second virial coefficient(A2) of HPAM decrease with increasing concentration of salt solutions,and the salt effect tends towards the maximum when the concentration of salt solution is increased to some amount.

STUDIES ON THE CHAIN STRUCTURAL EFFECT OF PVDF AND VDF (52)/TrFE(48) COPOLYMER BY MEANS OF THE METHOD OF DIELECTRIC RELAXATION

Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF （95 ）/VF （5）, VDF （52）/TrFE （48） and VDF（47. 5）/TrFE（47. 5）/HeFP （5） over a range of-120-140℃, 10-2-10;Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T;（3℃） of VDF （95）/VF （5）.Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF（52）/TrFE（48） decreased by 30℃ and T;by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.

Comparing the bullwhip effect under different inventory policies in engineering project supply chains

Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.

Size Effect on the Raman Spectra and Electronic Structure of the Glycine-alanine Oligopeptide Chains

A theoretical study on oligopeptide chains of glycine-alanine by density functional theory（DFT） is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbital, energy gap, atomic charge distribution, density of states and chemical activity of the side chain are studied at the B3LYP/6-31G（d） level. Results show that, with the number of residues increasing, vibrations of typical functional groups present Raman frequency shift, and the energy gap is gradually reduced. The HOMO and LUMO focus on the amino and carboxyl at the ends of oligopeptides. It is helpful for oligopeptides to self-assemble into chains. In addition, different residues（glycine or alanine） at the ends of chains result in the even-odd effect of orbital energy in the growth process. The size effects of physical and chemical properties only exist when the oligopeptides are shorter, and the phenomenon disappeared as the chain continues to grow.

Applying IT to Avoid Bullwhip Effect of Supply Chain

Bullwhip effect is the most important factor considered in the supply chain management. It gets many scholars＇ attention that bullwhip effect has been restricting the development of the supply chain all the time. Information Technology （IT） can reduce bullwhip effect by sharing the information among the enterprises in the supply chain.

Mechanism for Increasing Effective Inputs in Urban Agriculture through Industrial Value Chain

This paper firstly introduces the value chain management thought,current situations of utilization,and connotation of mechanism for increasing effective inputs in urban agriculture through industrial value chain.On the basis of basic idea of value chain management,this paper is to explore the mechanism for increasing effective inputs in urban agriculture through the value chain of urban agriculture linking with other industries.

Effective-field and Monte Carlo studies of mixed spin-2 and spin-1/2 Ising diamond chain

The magnetic properties of a mixed spin-2 and spin-1/2 ferromagnetic diamond chain are studied by effective-field theory and Monte Carlo（MC） simulation based on the Ising model.The temperature dependences of magnetization,magnetic susceptibility,internal energy,and specific heat are studied,respectively.The exchange interaction dependences of magnetization and the critical temperature are calculated by MC simulation.The changes of magnetization depending on the field increasing and then the field decreasing under steady-static conditions are also given.

数字经济发展如何影响城市碳排放?——来自中国283个地级市的经验数据

为探讨数字经济对城市碳排放的影响,基于2011—2020年中国283个地级以上城市的面板数据,构建综合评价指标体系测算数字经济指数,核算各城市碳排放量,采用SBM模型测算城市碳排放效率,并以产业结构高级化和合理化指数来刻画城市的产业结构升级,在此基础上进行计量分析。结果发现:数字经济发展能够提升碳排放效率,二者呈现出“U”型关系,数字经济发展能够降低碳排放强度和减少碳排放量,均呈现出倒“U”型关系;数字经济能够通过技术创新或产业结构升级影响碳排放,且技术创新和产业结构升级在数字经济与碳排放之间存在链式中介效应;数字经济、技术创新和产业结构升级对城市碳排放存在门槛效应,数字经济和技术创新在门槛值前后对碳排放效率的影响均呈现“先抑后扬”,对碳排放量的影响为“先扬后抑”,对碳排放强度跨越门槛后有显著的抑制作用,产业结构高级化和合理化指数跨越门槛值后能够提高碳排放效率、减少碳排放量,但对碳排放强度不产生影响。最后,基于实证结论提出了相应的政策建议。

Effect of Interaction on the Majorana Zero Modes in the Kitaev Chain at Half Filling

The one-dimensional interacting Kitaev chain at half filling is studied. The symmetry of the Hamiltonian is examined by dual transformations, and various physical quantities as a function of the fermion-fermion interaction U are calculated systematically using the density matrix renormalization group method. A special value of interaction Up is revealed in the topological region of the phase diagram. We show that at Up the ground states are strictly two-fold degenerate even though the chain length is finite and the zero-energy peak due to the Majorana zero modes is maximally enhanced and exactly localized at the end sites. Here Up may be attractive or repulsive depending on other system parameters. We also give a qualitative understanding of the effect of interaction under the self-consistent mean field framework.

A Study of the Bullwhip Effect for Short Life Cycle Products in Supply Chain Management

Shorter product life cycles present new dressed in supply chain literature. This research challenges to managing production and logistics not adequately adaddresses issues pertaining to the management of supply chains in a short life cycle environment. In this paper, we study the short life cycle environment; then we develop the ventory policy of the indirect manufacturer by explicitly using his demand us an output of the retailer＇s optimal inoptimal ordering policy. Finally, we also provide causes of the bullwhip effect in the context of short life cycle products.

循环经济产业链构造与协同效应

循环经济是一种技术范式变革的经济发展模式。文章在阐明循环经济产业链特征的基础上,深入探讨循环经济产业链构造过程与构造原理、循环经济协同效应机理。研究认为,循环经济产业链是系统协同的依托载体,产业链条反馈机制促使协同效应形成。为推进循环经济发展,应以立法创新为保障,确立废弃物资源属性核心理念,统筹推动废弃物梯级式循环利用;以政策机制创新为抓手,完善激励与考核机制,定期检视政策执行效果,推动循环经济产业链整合重构布局;以循环经济技术创新体系为支撑,围绕循环经济产业链部署创新链,以创新链布局产业链等政策建议,促进循环产业链构造,推动经济系统、资源系统和环境系统相互协同耦合共生。

企业社会责任存在供应链传染效应吗?——基于沪深A股上市公司的经验证据

利用沪深A股上市公司数据,考察处于供应链下游客户的社会责任表现如何影响上游供应商的社会责任履行。研究发现,社会责任表现良好的客户推动了供应商积极履行社会责任,即企业社会责任存在供应链传染效应,且主要表现在供应链责任和环境责任方面。更进一步,客户对供应商社会责任履行的促进作用具有动态效应,随着供应商与客户建立供应链关系持续的时间越长,企业社会责任的供应链传染效应越明显;当客户自愿披露社会责任报告、客户属于社会责任敏感行业或客户所在地区政府环境规制力度较大时,此时客户降低供应链风险的动机越强,企业社会责任的供应链传染效应越明显;当客户重要性水平较高、供应商产品独特性较弱或供应链关系较稳定时,此时客户降低供应链风险的能力越强,企业社会责任的供应链传染效应也越明显。研究还发现,客户驱动的供应商社会责任表现提高了供应商企业的绿色技术创新能力和企业价值。上述结果表明,客户为降低供应链风险,通过向供应商施加压力,推动了供应商积极履行社会责任。

关于制造业服务化环境效应动力机制与作用路径的文献综述

当前我国制造业在全球价值链分工体系中总体居于中低端,正面临资源环境约束增强、生产要素成本上升的困境,以资源要素投入为主、规模扩张为辅的粗放型经济增长方式难以持续。在此背景下,引导制造业和服务要素深度融合,构建绿色可持续发展的制造业新型产业形态,是兼顾经济效益和环境效益、实现制造业转型升级的重要方向。针对这一现象,国内外学者进行了深入探索。文章根据已有研究成果,基于环境效应角度,对制造业服务化相关的概念演化、动力机制以及作用路径等问题进行综述,并从研究角度和研究内容角度提出未来研究可以进一步深入的方向。

留守儿童领悟社会支持对学业情绪的影响——基于链式中介效应检验

为探讨留守儿童领悟社会支持对学业情绪的影响,并检验自尊和希望在此影响过程中的中介效应,课题组运用问卷调查法对1210名被试进行调查.结果表明,留守儿童的领悟社会支持正向预测积极学业情绪,负向预测消极学业情绪;自尊、希望在留守儿童领悟社会支持与学业情绪间起着链式中介作用.因此,家庭、学校、社区应当三方协同,提升留守儿童的社会支持水平,促使他们融入社会;积极引导,提高留守儿童的自尊水平;主动干预,促进留守儿童希望感的发展;采取多方面的措施,改善留守儿童的学业情绪.

“一带一路”倡议与全球价值链升级——基于沿线国家的实证数据

基于2007—2020年“一带一路”沿线国家的样本数据,利用多期双重差分模型实证检验了“一带一路”倡议对沿线国家的价值链升级作用。研究结果证实:“一带一路”倡议对于沿线国家全球价值链发展具有显著正向影响。机制分析表明:“一带一路”倡议对沿线国家存在“虹吸效应”,有利于沿线国家的发展。此外,政策沟通对于倡议的推行具有积极的促进作用。研究结果不仅证实了倡议对于沿线国家价值链升级的正向影响,也论证了其中存在的影响机制,为未来进一步的研究提供了理论支撑和有益探索。

电商政策的数字化效应:作用机制与双重溢出

迅猛发展的电子商务在数字经济催化下日益彰显出其对企业数字化转型的内生驱动力。以国家电子商务示范城市建设作为准自然实验,探讨国家电子商务示范城市试点政策对企业数字化转型的影响。研究表明:国家电子商务示范城市试点政策显著提高了企业数字化转型水平,该结论在一系列稳健性检验后依然成立;试点政策对中小企业、产业链下游企业、市场潜能高和政府财政赤字低的城市中的企业影响更为明显。成本效应、供需匹配效应、生产性服务业集聚效应与政府注意力分配效应是关键的中间作用机制。试点政策带动了消费互联网的发展,并使其与工业互联网建设产生协同效应,推动企业数字化转型。进一步分析表明,试点政策在电子商务发展较弱的地区主要表现出辐射带动的空间溢出效应,并通过产业链溢出效应促进了上游企业的数字化转型。研究结论为进一步优化电商政策的制定、促进企业高质量发展提供了政策启示。

长三角产业一体化高质量发展测度及时空演变规律

紧扣协议分工理论与高质量发展五大理念,采用面板熵权法测算了2007—2020年长三角41个城市产业一体化高质量发展水平,并综合空间探索性分析方法与空间马尔科夫方法揭示了长三角地区产业一体化高质量发展的空间分布特征与时空动态演变趋势。研究发现:①长三角地区的产业一体化、高质量发展及产业一体化高质量发展综合水平总体呈逐步上升趋势,且高质量发展水平高于产业一体化水平;②产业一体化高质量发展水平在空间上呈现“直辖市/省会城市高、东部高于西部、中心城市高于边缘城市”的特征;③各地区的产业一体化高质量发展具有空间依赖性,当周边城市等级高于本地区时,则会拉动本地区产业一体化高质量发展水平的提升,具有“扩散效应”;④长三角地区产业一体化高质量发展的聚类模式相对稳定,短期内不易改变。

全球价值链的脱钩与反脱钩:来自中国制造业企业微观数据的经验证据

本文基于中国制造业上市公司的微观数据和WIOD及亚行的世界投入产出表数据,考察美国的价值链脱钩策略对中国企业创新内在动力的激发效应和对中国全球价值链地位攀升的影响。研究发现:首先,美国的价值链脱钩策略对中国企业创新内在动力存在显著的正向激发作用,且激发效应能够抵消遏制效应。其次,脱钩策略对中国全球价值链地位攀升的叠加效应显著为正,与产业上游度负相关,表明美国的脱钩策略并不会阻断中国全球价值链地位的攀升和产业技术水平的提高。最后,中国企业自主创新对FDI技术外溢的吸收和转化等“学习效应”过于依赖,存在“低质低效”的双低现象,降低了价值链地位攀升的效率。FDI对产业价值链地位有显著的提升作用,但对国内企业“高质高效”的自主创新具有抑制作用。本文结论为提高企业自主创新质量和效率以及价值链地位提供了政策启示。

新质生产力与制造业产业链供应链韧性:理论分析与实证检验

新质生产力能够实现技术革命性突破、生产要素创新性配置、产业深度转型升级,为提升制造业产业链供应链韧性注入新动能.在构建城市层面新质生产力综合测度体系与制造业产业链供应链韧性指标基础上,使用2003-2020年154个地级市的平衡面板数据,实证分析新质生产力对制造业产业链供应链韧性的直接效应与空间溢出效应.研究发现:基准回归结果与异质性检验结果表明,新质生产力能够显著增强制造业产业链供应链韧性,这一结论在不同区域、不同产业结构合理化程度的地区中存在差异;空间计量回归结果表明,新质生产力不仅能够直接增强本地区制造业产业链供应链韧性,且会通过空间溢出效应对邻近地区制造业产业链供应链韧性产生正向影响;进一步分析结果表明,国内价值链的战略替代性能够正向调节新质生产力的制造业产业链供应链韧性提升效应.为制造业产业链供应链突破传统发展模式,提高自主可控能力提供有益参考.

考虑低碳补贴和技术延迟的供应链效应研究

为促进我国低碳经济的发展,政府对低碳产业采取补贴政策。考虑到技术普遍存在延迟效应,为避免其对政府低碳补贴、供应链各成员利润和社会福利带来的动态影响,选择一个零售商和一个制造商组成的二级供应链,并构建了其与政府之间关于延迟效应的微分博弈模型。本文分别统计了长视策略与短视策略两种情况分别在分散型决策和集中型政策下的最优策略、碳减排量和企业信誉演化路径,并将结果对比分析后经研究认为:政府的低碳补贴比率和技术延迟时间呈负相关,对企业的经营发展起到了促进作用。而技术延迟时间过长则会使得制造商选择短视政策,从而不利于企业利润和社会福利的发展。集中型决策下的减排量和社会福利总是最优的,但延迟时间在一定范围内供应链利润才是最优的,一旦超过这个范围分散型决策下的供应链利润高。