低共熔溶剂(DES)分级分离木质纤维素组分新技术

采用低共熔溶剂（DES）预处理木质纤维素,以提高残渣纤维素的酶解糖化效率。以稻壳为原料,从6种DES （乳酸-甘氨酸、草酸-氯化胆碱、甲酸-氯化胆碱、乙酸-氯化胆碱、甘油-氯化胆碱、乳酸-氯化胆碱）中,筛选脱木素效果最好的两种DES,即甲酸-氯化胆碱和乳酸-氯化胆碱;然后,利用上述2种DES预处理稻壳、玉米芯、樟木、杉木、800 kGy玉米芯等5种生物质原料,评价DES预处理生物质分离"三素"效果,结果表明甲酸-氯化胆碱预处理玉米芯分离"三素"效果最好;最后,优化了甲酸-氯化胆碱预处理玉米芯分离"三素"工艺参数,最佳参数为：时间120 min,温度115℃,投料量10%（质量分数）。在优化条件下,残渣纤维素含量74.31%,木质素脱除率81.49%,木质素纯度77.07%,半纤维素完全水解。XRD分析表明,残渣纤维素为Ⅰ型纤维素,结晶度48.57%;残渣纤维素酶解糖化效率为98.56%。     

基于TG-FTIR和Py-GC/MS的生物质三组分快速热解机理研究

利用热重红外联用仪(TG-FTIR)和快速热解-气相色谱/质谱联用仪(Py-GC/MS),对生物质三组分(纤维素、半纤维素和木质素)的热解失重规律、动力学和挥发分组分及其含量进行了对比研究。TG/DTG曲线表明,纤维素热解失重区间最窄,峰值处热解失重率最大;半纤维的最易发生降解,存在两个失重区间;而木质素热解过程最缓慢,热解温度范围最广。三维FTIR表明,纤维素热解主要产物为CO_2、醛类、酮类和酸类;半纤维素热解主要产物与纤维素一致,但是CO_2含量比其他几类组分高很多;木质素热解主要产物为CO_2和芳香烃类。Py-GC/MS分析表明,纤维素热解有机组分主要为呋喃类和脱水糖类,呋喃类产物在600℃时达到最大值43.34%,脱水糖类产物在500℃时达到最大值27.78%;半纤维素热解主要产物为酮类和呋喃类,两者含量随着热解温度增加呈逐渐下降趋势;木质素热解主要产物为酚类,总酚含量在热解温度500℃时达到最大值78%,其中愈创木酚型(G-型)酚的含量最高63.43%。     

木棉纤维成分及其微细结构分析

采用美国国家可再生能源实验室(National Renewable Energy Laboratory,NREL)标准测试法和美国纸浆与造纸工业技术协会(Technical Association of the Pulp and Paper Industry,TAPPI)标准测试法,分别测试了海南产木棉纤维的主体成分含量,发现以TAPPI法测试时因脱除木质素不彻底而导致测得的半纤维素含量偏高。采用NREL法测试了印尼木棉纤维的主体成分含量,与海南产木棉纤维主体成分含量相比:印尼木棉的纤维素、半纤维素含量略高,而木质素含量明显较低。木棉纤维在90℃下于质量分数为8%的氢氧化钠溶液中处理3h后,其中绝大多数半纤维素(84.2%)、小部分木质素(29.5%)被去除。当木质素或半纤维素与木质素一起被去除后,木棉纤维表面原纤网络结构显现出来。     

植物纤维的阳离子化改性及其对纤维结构的影响

通过对纤维阳离子化预处理过程进行优化,制备表面带有正电荷的阳离子纳纤化纤维素(CNFC).采用红外光谱(FTIR)、X射线衍射光谱(XRD)和热重分析(TG)对阳离子化前后纤维的结构和热稳定性变化进行分析.利用扫描电镜(SEM)对CNFC的表面形貌进行观察.结果表明最佳醚化条件为:醚化温度50℃、醚化时间2.5 h、NaOH与醚化剂EPTMAC的物质的量比为2.0,醚化剂EPTMAC与纤维素葡萄糖单元的物质的量比为1.5.经过阳离子化处理,纤维素的结晶度和热稳定性降低.     

新型深度共熔溶剂选择性分离木质素的研究

近年来,以胆碱类为代表的生物基离子液体作为木质素的优良溶剂逐渐受到广泛关注.文中基于Hansen溶解理论,设计出一种分别以乳酸(LA)和氯化胆碱(Ch Cl)为氢键供受体的新型离子液体——深度共熔溶剂(DES)作为木质素分离的溶剂.通过实验考察了常压下Ch Cl/LA摩尔比、温度、时间对木质素溶解效果的影响,确定了最佳工艺条件为Ch Cl/LA摩尔比1∶9、温度90℃、时间12h,此时木质素的溶解率达90.1%,再生木质素纯度为96.3%.紫外可见光谱(UV)及红外光谱(FT-IR)分析表明木粉中木质素经DES处理后被大量脱除;X射线衍射分析表明经预处理后的木粉中纤维素结构基本未被破坏;核磁共振谱(13C NMR)分析表明再生木质素由紫丁香基、愈创木基及少量对羟苯基结构单元组成;离子色谱分析结果表明该混合溶液中的综纤维素只有少量发生溶解.     

玉米秸秆纤维素高效分离工艺研究

采用有机酸混合液为溶剂、稀盐酸为催化剂,将玉米秸秆在常压下蒸煮,再经过氧化氢处理,将半纤维素和木质素与纤维素脱离,达到分离出纤维素的目的 .处理后的废液再经酸沉-醇析法,分离和回收半纤维素与木质素,实现秸秆资源的全组分分离.通过对纤维素分离工艺的探讨,确定了玉米秸秆组分分离实验的最佳工艺条件.结果表明,甲酸、乙酸和水体积比为30∶60∶10,反应温度90℃,反应时间4 h,粗纤维素以5%过氧化氢为溶剂,溶液pH为12,60℃条件下处理3 h,得到的纤维素纯度可达到94.2%,纤维素、木质素和半纤维素的回收率分别为88.9%、75.6%和28.5%.     

双相水溶液法制备乌拉草纤维

采用双相水(聚乙二醇(PEG)-2 000/无机盐)溶液法制备乌拉草纤维.首先对原料进行预氧处理,然后进行双相水溶液处理以脱除余下的非纤维素物质,并用单因子控制变量法对该工艺进行优化,最后对采用最佳处理工艺得到的纤维进行测试与表征.结果表明:双相水溶液处理的最佳工艺条件,即为10%PEG-2 000,2.5%NaOH,1.5%Na2SO3,1.5%Na2CO3,浴比1∶20,处理温度为90℃,处理时间为2h;测试得到纤维的平均长度、线密度、回潮率、结晶度、拉伸断裂强度分别为30mm、2.72tex、10.66%、42%、1.84cN/dtex;乌拉草及其纤维均主要含有纤维素、木质素和半纤维素,处理后纤维素含量显著提高,而木质素和半纤维素含量降低;乌拉草纵向凹凸不平,横向呈波浪状,且波峰部分由孔洞结构组成,波谷部分由实心物质组成;纤维纵向基本平直,单根纤维表面有少量杂质.     

羟基自由基活性氧处理机械草浆分离半纤维素和木质素

基于生物质精炼与制浆相结合的构想,采用羟基自由基活性氧处理机械草浆,分离半纤维素和木质素,探讨了温度（T）、反应时间（t）、H₂O₂浓度质量分数（w）和固液比（r）等因素对半纤维素、木质素提取效果的影响。实验结果表明：在T=160℃,t=2h,w(H₂O₂)=1.5%,r=5g/L的反应条件下,半纤维素和木质素脱除率最高,分别达到82.68%,91.22%。     

CSLF法提取蔗渣半纤维素工艺条件的响应面优化

利用中心组合设计法(CCD),对蔗渣半纤维素的纤维素溶剂的木质纤维素组分分离(CSLF法)进行优化.在单因素实验的基础上,确定磷酸质量分数、磷酸蔗渣液固比和水浴温度是影响蔗渣半纤维素提取的3个关键因素.以半纤维素提取率为响应目标,采用CCD和响应面分析法(RSM),确定CSLF法半纤维素的最佳提取工艺:磷酸质量分数为83%,磷酸蔗渣液固比为8.95 mL·g^-1和水浴温度为48.94 ℃.结果表明:蔗渣半纤维素提取率可达到75.29%,比优化前提高9%.     

牛角瓜、木棉和棉纤维的成分、结构和性能分析

牛角瓜、木棉和棉纤维均属于天然纤维素纤维.研究了牛角瓜纤维的物理性能参数、形态结构、微结构以及主要化学成分质量分数,并与木棉和棉纤维进行比较.结果表明,牛角瓜纤维断裂强度为4.45cN/dtex,断裂伸长率为3.40%,回潮率为11.90%;采用扫描电子显微镜(SEM)对牛角瓜纤维的形态结构进行测试,发现横截面的中空度为80%～90%,纵向表面光滑,无天然扭曲;采用X-射线衍射仪(XRD)测得纤维的结晶度为42.54%,晶区取向指数为85.40%;采用热分析仪测得初始降解温度为301.1℃;采用傅里叶变换红外-拉曼光谱仪(FTIR-Raman)测得纤维有木质素和纤维素的红外特征峰;利用化学方法测得纤维中木质素质量分数为8%～9%,纤维素约为64%,半纤维素约为20%,蜡质为2%～3%,果胶约为3%,灰分为1.2%～1.8%.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has