乙醇体系中碱式氯化镁制备纤维状氢氧化镁的工艺

纤维状氢氧化镁应用于高分子复合材料具有较好的阻燃及补强增韧作用,是具有较好发展前景的无卤阻燃剂,其研究和应用受到密切关注。本文在乙醇溶液中,以纤维状碱式氯化镁(Mg2(OH)3Cl·4H2O)和氢氧化钠为原料研究制备了纤维状氢氧化镁。实验考察了物料摩尔比、乙醇浓度、反应温度和碱式氯化镁浆料浓度等因素对转化时间及氢氧化镁形貌的影响规律,并以SEM和XRD对产品形貌和结构进行了表征分析。实验结果表明,氢氧化钠与碱式氯化镁摩尔比为2.5∶1,当溶剂为75%乙醇,反应温度为30℃,碱式氯化镁浓度为0.25 mol/L时,反应只需5 h左右,即可得到表面光滑,粒径约为30-50μm,直径约0.3μm,长径比达到100-120的纤维状氢氧化镁,转化率可达100%。该工艺对氢氧化钠需求量少,可在较短时间内得到长径比较大的纤维状氢氧化镁,更适合于工业化生产。     

纳米氢氧化镁晶体阻燃剂的制备及其性质

以氯化镁、硫酸镁及氢氧化钠为原料,采用水热法制备了尺寸在50nm左右的氢氧化镁纳米晶。用XRD、TEM、BET等对纳米晶的化学成分、大小、结构及表面积大小进行了表征。采用TG、DSC对产品的热学性质进行了研究,结果表明:作为阻燃剂,纳米晶氢氧化镁具有比常规微米级氢氧化镁更为优越的热学性质。对影响纳米晶尺寸的因素及应用于阻燃剂的可行性进行了分析。     

4-甲基吡啶在Ti/nanoTiO2-Pt电极上的电催化氧化

采用溶胶-凝胶和扫描电沉积法制备Ti基纳米TiO2-Pt(Ti/nanoTiO2-Pt)膜电极,Pt纳米粒子的平均粒径约为25nm.在离子液体+DMF(体积比为1:1)的混合溶剂中,通过循环伏安和计时电流法研究表明, Ti/nanoTiO2-Pt修饰电极对4-甲基吡啶(4-MP)的氧化具有高催化活性,同时讨论了4-甲基吡啶电催化氧化的机理.     

钯晶种镍纳米颗粒的制备和表征

寻求镍纳米颗粒制备的有效方法及反应条件．以钯纳米颗粒为晶种制备出了镍纳米颗粒，并对影响镍纳米颗粒制备的各种因素即温度、浓度、PVP、Pd和水合肼等进行了探索．结果表明：当摩尔比npd：nNi2＋=1：40时，反应时间仅用20min．npvp：nNi^2＋=40：1时，PVP对镍纳米胶体的稳定效果最好，14d之内不会聚沉，镍纳米颗粒的平均粒径约13nm，远小于不用钯纳米颗粒为晶种所制得的镍纳米颗粒粒径（约40nm）．以紫外一可见光谱表征反应进程，TEM表征经无水乙醇稀释后的胶体形貌，XPS表征元素化合价以及XRD表征其晶形．     

用低品位菱镁矿制取高纯镁砂

研究一种以低品位菱镁矿为原料制取高纯镁砂的新方法。首先，用氯化铵溶液作浸出剂与菱镁矿轻烧粉反应分离硅、铁和铝等杂质，得到以氯化镁为主要成分的浸出液，将反应过程中产生的氨用纯水吸收；然后，将浸出液直接与回收氨进行沉镁反应制备氢氧化镁；最后，将氢氧化镁进行两步煅烧得到高纯镁砂。沉镁反应产生的氯化铵母液可循环使用。研究结果表明：在800℃将氢氧化镁轻烧2．5h，得到的轻烧粉活性最高。在温度为110℃、液目比为9、时间为60min时，一段浸出时镁浸出率可这80％，浸出液中Mg^2＋质量浓度为65．6g／L。用氨法沉镁制备的Mg（OH）2颗粒大、过滤性能好，滤饼含水率为12％；镁砂产品的氧化镁含量高达99．97％。     

高分散高微细阻燃型氢氧化镁合成工艺的研究

以六水合氯化镁(MgCl2·6H2O)和氢氧化钠(NaOH)为原料,十二烷基硫酸钠和乙醇为分散剂,采用液相沉淀法制备氢氧化镁(Mg(OH)2)阻燃剂,设计正交试验,研究了投料顺序、分散剂用量、反应温度、反应物浓度及浓度配比对其粒径和吸光度的影响;采用电子扫描显微镜(SEM)、X射线衍射仪(XRD)对其特性进行对比表征。结果显示最佳制备工艺为:投料顺序为向氯化镁和分散剂的混合溶液中滴加氢氧化钠,分散剂用量(分散剂质量与理论所得氢氧化镁质量之比)为6%,反应温度为50℃,反应物氯化镁溶液浓度为0.75mol/L,氯化镁与氢氧化钠浓度配比为1∶2。表明此合成方法的工艺简便、条件缓和,合成的阻燃型氢氧化镁与市售样品相比,具有颗粒均匀、粒径更小、分布更窄的特点,颗粒的极性、分散性、抗团聚性等性能全面优于市售样品。     

2-氯吡啶氮氧化物的合成方法研究

对以2-氯吡啶为原料、双氧水为氧化剂、钨酸和硫酸为催化剂合成2-氯吡啶-N-氧化物的方法进行了反复实验．该方法的最佳反应条件为：催化剂浓H2SO4与2-氯吡啶的体积分数为0．2：1．0～0．3：1．0，2-氯吡啶与钨酸的物质的量比为18．5：1—20．8：1，反应中H2O2与2-氯吡啶的物质的量比为1．3：1～1．5：1，反应最适温度为70～80℃，满足这些条件的反应产率为90％以上．     

无机玻璃钢烟囱制法

无机玻璃钢烟囱走俏市场，效益显著。它具有耐高温、抗老化、强度高、安装方便灵活、使用寿命长等优点。其制法简单易行。设备工具拌料地、成型支架、木质锥形圆柱模型若干、塑料膜、胶手套、拌料工具等。原料配方（重量％）主料：氧化镁64．8，氯化镁25．6；辅料：滑石粉6．4；化学试剂：硫酸亚铁0．064，氢氧化钠0．064，减水剂MS－1与MS－2各0．064，MS－3为2．57，尿醛树脂胶0．436，氯化铵0．002。制法（1）拌浆将氯化镁倒入拌料地内，兑水配成波美25度氯化镁水溶液。将化学试剂溶解后倒入氯化镁水溶液中搅匀。把氯化镁。滑石粉混合…     

纳米固体超强酸SO42-/Fe2O3催化合成没食子酸正丁酯的研究

以FeCl3盐溶液为原料制备了纳米固体超强酸催化剂SO42-/Fe2O3,透射电镜(TEM)测定结果表明粒径约100nm,探讨了催化剂焙烧温度、焙烧时间对催化剂性能的影响.以纳米固体超强酸SO42-/Fe2O3为催化剂,由没食子酸与正丁醇直接酯化合成没食子酸正丁酯.通过正交实验研究了影响没食子酸正丁酯产率的主要因素,得到最优实验条件为:醇酸物质的量比为6/1,催化剂用量为反应物总质量的3%,反应时间为2h.其中反应时间为主要影响因素.     

化学沉淀法制备纳米钛酸镁粉体

以TiCl₄和MgCl₂混合液为原料液、NaOH为沉淀剂，采用化学沉淀法制备纳米钛酸镁粉体。考察了沉淀剂浓度、原料液中Mg²⁺与Ti⁴⁺的摩尔比、煅烧温度等因素对目的产物颗粒大小和晶型的影响;采用透射电镜和X射线衍射等多种分析测试方法对制得粉体进行了表征。实验结果表明：当镁钛混合液中的Mg²⁺与Ti⁴⁺的摩尔比为1.2（固定钛离子浓度为0.5mol/L）、沉淀剂NaOH浓度为6mol/L、反应温度98℃、镁钛混合液与NaOH溶液的体积比为1:1、煅烧温度为800℃时，制备出了平均粒径约为55nm、结晶度好、形貌为球形的纳米钛酸镁粉体。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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