STUDY OF THE MOLECULAR MOTION AND COMPATIBILITY IN AB-CROSSLINKED POLYMER BASED ON POLYURETHANE AND POLYSTYRENE-co-ACRYLIC ACID BY SOLID STATE HIGH RESOLUTION NMR

The ^(13)C T_(1s) of --CH_3 side group in PPU/P (St-co-AA), AB-crosslinked polymers (i. e.ABCP) was studied by using high resolution solid state NMR. The rotation motion of --CH_3 sidegroup in PPU was analyzed by means of the average spectral density functions of internal rota-tion. The results showed that the rotation of the --CH_3 side group is related closely to the com-patibility between the two components. The compatibility was studied by analyzing the protonspin-lattice relaxation in rotating frame, spin-spin relaxation and spin-diffusion. The resultsshowed that the hydrogen bonds between the components play a major role in determining thecompatibility. Through spin diffusion studying, the soft phase domain size was calculated. Bystudying proton spin-spin relaxation, the content of each component in each phase and that ofeach phase in the samples can be obtained. The result shows that the content of interphase is related closely to the compatibility.

Molecular investigation on the compatibility of epoxy resin with liquid oxygen

Conventional fiber reinforced plastics(FRPs)have compatibility issues with solid oxygen while used as a fuel tank,which might cause combustion and explosion.To study the compatibility of different epoxy resins with liquid oxygen,molecular dynamics was used to simulate the phase changes of cross-linked epoxy resins under the impact of solid oxygen.Three curing resin systems,which are bisphenol A epoxy resin(DGEBA),bisphenol F epoxy resin(DGEBF),and tetrahydrophthalate diglycidyl ester(epoxy resin 711),are modeled to investigate the rational material system for the application of fuel tanks in launching vehicles.The simulation results show that the order of solid oxygen compatibility of these epoxy resins is DGEBA>DGEBF>epoxy resin 711 at the same density of crosslinking.The selection of curing agent also has an impact on the compatibility,with the same epoxy,diaminodiphenyl methane(DDM)has more advanced performance comparing to diaminodiphenyl sulfone(DDS).

STUDY OF THE MOLECULAR MOTION IN POLYEPICHLOROHYDRIN BY HIGH RESOLUTION NMR

The molecular motion in polyepichlorohydrin (PEPCH), in solution and bulk, was studied by high resolution NMR by means of line width, spin-lattice relaxation time T_1 and nuclear Overhauser effect NOE. The results show that the VJGM model can describe the main chain motion of PEPCH in solution perfectly. In bulk state, the relationship between the line width and the temperature is consistent with WLF equation, but that between the high frequency molecular motion correlation time (in T_1 scale ) and temperature is consistent with Arrhenius equation. The motion parameters of PEPCH in both states were calculated. The internal rotation motion of side—CH_2Cl group was analyzed by using equal three-site jump and diffusion internal rotation model in both states.

Evaluation of Compatibilizers for Improving Compatibility between Waste Vegetable Oil and Aged Asphalt

Modifying agents 2,2-Bis(4-glycidyloxyphenyl)propane(2BPE)and dibutyl phthalate(DBP)were selected to enhance the compatibility.By using molecular simulation software(Materials Studio,MS),nine systems were constructed,including molecular models of aged asphalt and WVO monomers with 2BPE and/or DBP.The solubility parameters,Flory-Huggins parameters,and interaction energies of these systems were calculated to determine the impact of 2BPE and DBP on the compatibility of WVO and aged asphalt.Results showed that the addition of 2BPE and DBP reduced the difference in the solubility parameters between WVO and aged asphalt,thus improving the compatibility between WVO and aged asphalt.Additionally,using a combination of 2BPE and DBP in both aged asphalt and rejuvenator was found to be more effective than using either 2BPE or DBP alone.Finally,it was determined that evaluating the compatibility of WVO and aged asphalt using Van der Waals potential and non-bonding energy as evaluation indicators was more accurate than using electrostatic potential energy.

Molecular dynamics simulations on the dynamics of two-dimensional rounded squares

The collective motion of rounded squares with different comer-roundness ζ is studied by molecular dynamlcs （MD） simulation in this work. Three types of translational collective motion pattern are observed, including＇, gliding, hopping and a mixture of gliding and hopping. Quantitatively, the dynamics of each observed ordered phase is characterized by both mean square displacement and van Hove functions for both translation and rotation. The effect of corner-roundness on the dynamics is further studied by comparing the dynamics of the rhombic crystal phases folmed by different comer-.rounded particles at a same surface fraction. The results show that as ζ increases from 0.286 to 0.667, the translational collective motion of particles changes from a gliding-dominant pattern to a hopping-dominant patte;n, whereas the rotational motion pattern is hopping-like and does not change in its type, but the rotational hopping becomes much more frequent as increases （i.e., as particles become more rounded）. A simple geometrical model is proposed to explain the trend of gliding motion observed in MD simulations.

Rate efect and coupled evolution of atomic motions and potential landscapes

Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mecha- nisms underlying the strain rate effects.

Blood Compatibility of Amphiphilic Poly(N-α-acrylamide-L-lysine-<i>b</i>-dimethylsiloxane) Block Copolymers

Amphiphilic block copolymers poly(LysAA-b-DMS) consisting of a hydrophilic poly(N-α-acrylamide-L-lysine) [poly(LysAA)] segment with different molecular weights and a hydrophobic polydimethylsiloxane (PDMS) segment were prepared as follows. The precursor copolymer poly(Boc-LysAA-OtBu-b-PDMS) was obtained from radical polymerization of N-α-acrylamide-N-ε-tert-butoxycarbonyl-L-lysine-tert-butylester (Boc-LysAA-OtBu) initiated with 4,4’-azobis(polydimethylsiloxane 4-cyanopentanoate) (azo-PDMS) with the molecular weight of PDMS Mw = 4.3 × 103 in the presence of 2-mercaptoethanol (2-ME) as a chain-transfer agent. Removal of the protecting groups of the precursor copolymer was carried out in 80% trifluoroacetic acid aqueous solution to give poly(LysAA-b-DMS)-1-3. The weight average molecular weight of poly(LysAA-b-DMS)-1-3 was Mw = 1.02 × 104 – 2.52 × 104. From the 1H-NMR and fluorescence spectra measurements, poly(LysAA-b-DMS)-1-3 was determined to self-organize and form core-shell micelles in water. The critical micelle concentration (CMC) increased to 1000 - 4000 mg·L–1 with increasing molar ratio of the poly(LysAA) segment from 0.42 to 0.65. From morphological analysis with a scanning probe microscope (SPM), poly(LysAA-b-DMS) has microphase-separated structures made up of hydrophilic and hydrophobic regions with the domain size ranging from several tens to several hundreds of nanometers. Inhibition of thrombin activity of poly(LysAA-b-DMS) was evaluated from the Michaelis constant (KM) and catalytic activity (kcat) for the enzymatic reaction of thrombin and synthetic substrate S-2238 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.10 - 0.11 mM and 4.04 × 105 – 4.26 × 105 min–1, respectively. Fibrinolytic activity was also verified from the transformation of plasminogen to plasmin by tissue plasminogen activator (t-PA) using synthetic substrate S-2251 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.07 mM and 5.73 × 106 –5.95 × 106 min–1, respectively.

A modified method for simulating non-stationary multi-point earthquake ground motion

A spectral-representation-based algorithm is proposed to simulate non-stationary and stochastic processes with evolutionary power,according to a prescribed non-stationary cross-spectral density matrix. Non-stationary multi-point seismic ground motions at different locations on the ground surface are generated for use in engineering applications. First,a modified iterative procedure is used to generate uniformly modulated non-stationary ground motion time histories which are compatible with the prescribed power spectrum. Then,ground motion time histories are modeled as a non-stationary stochastic process with amplitude and frequency modulation. The characteristic frequency and damping ratio of the Clough-Penzien acceleration spectrum are considered as a function of time in order to study the frequency time variation. Finally,two numerical examples are presented to validate the efficiency of the proposed method,and the results show that this method can be effectively applied to the dynamic seismic analysis of long and large scale structures.

利用分子检测和基因编辑快速创制籼粳杂种亲和材料

[目的]利用分子检测和基因编辑技术,快速精准创制籼粳人工亲和系材料,打破籼粳杂种不育,为实现远缘杂种优势利用提供新范例。[方法]本研究以优质籼稻‘黄华占’(HHZ)和优质粳稻‘中嘉8号’(ZJ8)为测试底盘,利用分子检测技术,检测HHZ和ZJ8中影响籼粳杂种不育的主效座位基因型,结合基因编辑技术,对影响HHZ与ZJ8杂种F1育性的主效座位进行基因敲除,从而快速精准创建具有高结实率的HHZ与ZJ8籼粳杂种F1。[结果]HHZ与ZJ8杂种F1表现出强大的杂种优势,但其小穗育性为半不育。根据籼粳稻亚种间杂种不育已有认知,通过分子检测,发现该杂交组合存在一个已克隆的杂种不育主效座位S5。为此,本研究利用基因编辑技术,分别敲除S5座位籼稻的杀手基因ORF5+和粳稻的帮凶基因ORF4+,与野生型相比,这些编辑材料的重要农艺性状无明显变化。但这些编辑材料分别与野生型ZJ8和HHZ杂交获得的杂种F1的小穗育性能够完全恢复到全可育。[结论]利用分子检测和基因编辑能实现籼粳杂交育种的理性设计,快速培育出籼粳亲和型材料,最大程度地保留籼粳稻遗传多样性,为突破籼粳杂种不育和实现籼粳杂种优势的充分利用提供了一种新模式。

Elemene Antitumor Drugs Development Based on "Molecular Compatibility Theory" and Clinical Application: A Retrospective and Prospective Outlook

Elemene, derived from Curcuma wenyujin, one of the "8 famous genuine medicinal materials of Zhejiang province," exhibits remarkable antitumor activity. It has gained wide recognition in clinical practice for effectiveness on tumors. Dr. XIE Tian introduced the innovative concept of "molecular compatibility theory" by combining Chinese medicine principles, specifically the "monarch, minister, assistant, and envoy" theory, with modern biomedical technology. This groundbreaking approach, along with a systematic analysis of Chinese medicine and modern biomedical knowledge, led to the development of elemene nanoliposome formulations. These novel formulations offer numerous advantages, including low toxicity, well-defined composition, synergistic effects on multiple targets, and excellent biocompatibility. Following the principles of the "molecular compatibility theory", further exploration of cancer treatment strategies and methods based on elemene was undertaken. This comprehensive review consolidates the current understanding of elemene's potential antitumor mechanisms, recent clinical investigations, advancements in drug delivery systems, and structural modifications. The ultimate goal of this review is to establish a solid theoretical foundation for researchers, empowering them to develop more effective antitumor drugs based on the principles of "molecular compatibility theory".

SEBS与常用单质炸药的相容性研究

将分子动力学(MD)模拟方法中理论键长变化趋势与差示扫描量热法(DSC)测得的分解温度变化情况相结合,分析了热塑性弹性体氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)与推进剂中常用的单质炸药黑索今(RDX)、奥克托今(HMX)、六硝基六氮杂异伍兹烷(CL-20)之间的相容性。MD模拟结果表明:RDX、HMX、CL-20与SEBS共混体系的引发键最大键长随温度的升高而增加,与单质炸药单组分体系相比均没有明显的变化,推测SEBS与RDX、HMX、CL-20共混后稳定性较好,不易发生引发键的断裂。DSC结果中,RDX、HMX、CL-20与SEBS共混后,热分解温度变化均在3℃以内,表明SEBS与RDX、HMX和CL-20之间相容性好。进一步,选择相容性差的二号中定剂(C_(2))和3,4-二硝基呋咱基氧化呋咱(DNTF)作为对照体系,进行MD模拟和DSC分析发现,引发键最大键长明显增加,DSC热分解温度提前了70℃以上,验证了引发键键长预测相容性优劣的可行性。

基于无监督学习方法的细胞膜内单分子扩散运动分析:胆固醇对模型膜和活细胞膜流动性的不同影响

单分子运动追踪是研究软物质体系尤其是生命体系动力学过程和分子相互作用的重要方法,但如何理解生命体系中单分子运动行为的复杂性仍是一个巨大的挑战.针对这一问题,本工作提出了一种可对单分子轨迹进行高效识别和分类的、基于无监督学习的“两步归类法”:首先利用熵约束最小二乘法对扩散轨迹的受限程度进行区分,继而通过统计检验将非受限轨迹划分为亚扩散、正常扩散和超扩散等不同运动模式类型.利用该方法,本工作解析了DOPC模型细胞膜和活细胞膜内的单分子扩散运动特征,揭示了胆固醇成分对二者的差异影响.结果显示:模型膜和活细胞膜均包含多种不同的扩散模式;在DOPC模型膜体系中,胆固醇成分会阻碍膜内的分子扩散运动,且阻碍程度与胆固醇含量正相关;在活细胞体系中,分子运动速率显著低于模型膜体系,并且,胆固醇的去除会进一步减慢分子扩散速率.本研究有助于从单分子运动角度深入理解生物分子运动行为的复杂性及其对体系环境的依赖性.

电磁学中的格林函数

文章回顾了电磁学中的格林函数理论与格林函数方法。首先,引入标量波动方程对应的格林函数,并与信号系统中的冲击响应函数作类比。其次,引入矢量波动方程对应的并矢格林函数,包括均匀和非均匀介质中的格林函数,并探讨其与电磁理论中的互易定理、等效原理之间的联系。最后,介绍了考虑介质的运动效应和电磁场的量子效应下的格林函数理论。此外,文章也探讨了电磁格林函数在无线通信、电磁兼容等工程领域的应用。

热氧老化对马来酸酐接枝聚丙烯的结构与性能的影响

以自制的马来酸酐接枝聚丙烯(PP-g-MAH)为研究对象,研究了PP-g-MAH对玻璃纤维增强聚丙烯材料性能的影响以及热氧老化对PP-g-MAH分子结构和性能的影响。结果表明,自制的PP-g-MAH大幅度提高了30%玻纤增强聚丙烯材料的力学性能;随着热氧老化时间的延长,PP-g-MAH的MFR不断增加,对玻璃纤维增强聚丙烯材料的力学性能的提升作用不断降低;通过凝胶色谱仪(GPC)、红外光谱(IR)和马来酸酐(MAH)接枝率测定结果的分析,热氧老化过程没有对PP分子链接枝的马来酸酐产生明显的影响,而是引起了聚丙烯分子链的断裂,造成PP-g-MAH分子量下降,导致自身力学性能下降,使得PP与玻璃纤维之间的界面强度下降,使得PP-g-MAH对玻璃纤维增强聚丙烯材料的力学性能提升作用下降。

拟合楼层反应谱的三向地震动时程生成方法研究

为获得满足规范要求的拟合楼层反应谱的三向地震动时程,采用六阶常微分方程的本征函数为基函数,分解并重构天然地震动时程;通过构建影响矩阵,迭代计算逐步调整本征函数的幅值系数,最终实现预设拟合精度;引入正交化方法保证三向地震动时程两两之间的统计独立性,并通过两组算例提供验证。研究结果表明,迭代所得时程反应谱与目标楼层反应谱的拟合精度较高,迭代过程中时程反应谱均匀一致地向目标谱逼近,迭代过程收敛,所得三向地震动时程均无零飘现象,满足规范要求。

C_(6)F_(12)O混合气体与三元乙丙橡胶的相容性研究

C_(6)F_(12)O作为一种新型环保绝缘气体,与缓冲气体混合后具有作为绝缘介质运用于中低压电气设备的潜力。然而,环保气体绝缘设备内的密封材料是否与C_(6)F_(12)O长期兼容还有待深入研究。为此,本文研究了C_(6)F_(12)O/CO_(2)混合气体与气体绝缘设备中常用的三元乙丙橡胶(EPDM)的相容性和O_(2)对C_(6)F_(12)O/CO_(2)混合气体与EPDM相容性的影响。本文搭建了气固相容性实验平台,并结合实际运行温度进行不同温度下C_(6)F_(12)O混合气体与EPDM的相容性实验,测试了实验后EPDM的表面形貌、表面元素、力学性能和气体成分的变化,以确定C_(6)F_(12)O混合气体与EP-DM的长期相容性。同时,构建了C_(6)F_(12)O混合气体与EPDM分子链的仿真模型,基于分子动力学(MD)理论计算了C_(6)F_(12)O、CO_(2)与EPDM之间的扩散系数、相互作用参数和混合能。结果表明:在110℃热加速实验后EPDM表面产生鳞状结构,并在EPDM表面检测到C—F键、有机氟化物和金属氟化物,EPDM的力学性能降低,实验后主要气体产物为C_(3)F_(6)和C_(3)F_(7)H。加入O_(2)后,EPDM在90℃时表面出现凸起,并且有大量O、F元素积累在表面,EPDM力学性能下降,气体产物增多。理论计算也表明升高温度和加入O_(2)会加速C_(6)F_(12)O混合气体在EPDM中的扩散,导致气体分子与EPDM相容性变差。本文的研究成果将为C_(6)F_(12)O气体绝缘设备的设计和制造过程提供参考。

Photoinduced Bending and Curling Motions in Molecular Microcrystals of Naphthyl Meldrum’s Acid Derivative Based on E-to-Z Photoisomerization

Dynamic photoresponsive molecular crystals are promising candidates for making intelligent devices and materials in the future.Here,we synthesized a new photoactive molecule(E)-2,2-dimethyl-5-[3-(naphthalen-1-yl)allylide]-1,3-dioxane-4,6-dione[(E)-DNADD]that undergoes an E-to-Z photoisomerization in both liquid solution and solids when exposed to visible light(405 nm).Compared to the bulk crystals,the photoresponsive behavior in microcrystals was profoundly improved.Highly crystalline(E)-DNADD microplate crystals exhibit robust motions,including bending,curling,and coiling under light irradiation.The photoproduct conversion of the photochemical reaction in the microplate is no more than 20%,while the large bending curvature of the coiled illuminated samples was estimated at approximately 150–300 mm−1,comparable to some photoactive nanowires.Our results indicate that shrinking crystal dimensions can boost the photoresponses in molecular crystals and provide a facile strategy for developing dynamic molecular crystals at the microscopic scale.

Terahertz Electric Field Induced Double Strand Breakage and Vibrations of dsDNA in a Gold Nanoslit

Objective This work examines the impact of external electric fields at terahertz(THz)frequencies on doublestranded deoxyribonucleic acid(dsDNA)systems adsorbed on Au(111)surfaces in aqueous environments.Methods The investigation utilizes a molecular dynamics(MD)approach at the atomic level and vibrational dynamics calculations using the GolDNA-Amber force field.Results The results reveal that the sugar-phosphate backbone of the DNA exhibits reduced adherence to the gold surface,while the side chains display a stronger affinity.When subjecting the hydrated DNA strands to an electric field with frequencies up to 10 THz,peak intensities of vibrational dynamic density(VDoS)are observed at five different frequencies.Moreover,the strong electric field causes hydrogen bonds in the DNA within the slit to break.The sensitivity to the electric field is particularly pronounced at 8.8 THz and 9.6 THz,with different vibrational modes observed at varying electric field strengths.Conclusion These findings contribute to an enhanced understanding of the molecular organization of gold-plated charged biological interfaces.

硅酮密封胶与增塑剂相容性的分子动力学模拟

硅酮密封胶与增塑剂的相容性关系到建筑密封胶的使用性能,这不仅影响到建筑物的美观,更严重影响了幕墙系统的安全性及使用寿命。采用分子动力学模拟方法在COMPASSⅡ力场下,对白油、甲基硅油、脱酮肟硅酮密封胶的纯物质及脱酮肟/白油、脱酮肟/甲基硅油共混物的密度、内聚能密度、溶度参数、径向分布函数、修金斯参数(χ)值、结合能(Ebind)、混合能(Emix)进行了模拟计算。通过溶度参数差值|Δδ|、Blends结合能、混合能、χ值、径向分布函数值及共混体系模拟前后的密度变化表征硅酮密封胶与增塑剂间的相容性。结果表明:白油与脱酮肟型密封胶分子间作用较弱,相容性较差;而甲基硅油与脱酮肟型密封胶分子间作用较强,具有更好的相容性。

正十七烷在伊利石狭缝孔隙中的吸附与赋存规律研究

采用巨正则蒙特卡洛(GCMC)和分子动力学(MD)方法,利用Materials Studio 2020构建了4 nm、8 nm、15 nm和50 nm的伊利石狭缝孔隙模型,对研究区北部湾盆地涠西南凹陷区流二段油页岩原油主体组分正十七烷(CH 3(CH 2)15 CH 3)进行了吸附规律和扩散现象研究。研究表明,原油的吸附能力受到压力和孔径的影响较大,受温度影响相对较小。大孔径模型可以提供更多赋存空间,大量的吸附位导致大孔径模型的容纳能力强于小孔径模型的吸附能力,当狭缝孔壁吸附位被大量占据时,原油主要以游离态赋存于狭缝孔中。相同边界条件和温压条件下,绝对吸附量随着压力的增大而增加,绝对吸附量随着温度的增加呈递减趋势;烷烃在吸附和扩散运移中,分子总是向着狭缝片层方向运动,在狭缝壁面附近形成吸附层,4 nm、8 nm、15 nm和50 nm的伊利石狭缝孔中出现2个吸附层,距离孔隙中心分别约0.34 nm,3.67 nm,7.25 nm和24.21 nm处,最大吸附密度分别为0.40 g/cm 3,0.40 g/cm 3,0.28 g/cm 3和0.37 g/cm 3;烃类物质在页岩中的赋存状态主要可分为3个区,孔径小于2.3 nm的小分子吸附区,2.3~3.9 nm为强吸附区,大于3.9 nm为弱吸附区,伊利石对正十七烷的吸附行为均为物理吸附。