中国古代造酒的化学工艺

酒是人类知道火食以后,最早制造的嗜好品饮料。所以,未开化的国家。也往往有酒。但酒的制法,各国各地不同。古今的酒的制法和气味,也不能一致。我国的酒,依史籍上考证,孟子说:“禹恶旨酒”。战国策是战国时人著的,它也记载说:“仪狄(人名)作酒,禹饮而甘之。曰,后世必有以酒亡其国者。遂疏仪狄而绝旨酒”。可见,夏禹时候已有了酒。而旨酒是美酒,仪狄做的特别美。禹怕给他做的美酒耽误事,所以不愿喝他的酒,和他疏远了。想在仪狄以前,也许早有做酒的,不过史书上没有记载。有人因黄帝素问和神农本草经已载了     

我们是怎样进行复习展览的

通过通报的介绍,与友校的经验,我们于大前年举行了一次复习展览。以后每学期按期举行,并在平日选定一些专题作展览,陈列在图书馆的阅览室,与实验室门前通路上。如酸,硷,盐性质比较,金属非金属标本,煤,石油等专题。在摸索过程中,首先是贪多,选好看的,整套的多排,以致内容分散。以后又过于简略。首先是安排实验,再考虑给予思考题。后来是整理综合成为几个项目,分别拟具思考题,再研究陈列些什么东西。每次进行筹备计划性逐渐加强,考虑的问题也比较集中。(1)准备复习展览的陈列,应在钻研教材的基础上,明确重点,选择主要教材,和能说明本质的实验装置和直观教具。只有掌握化学教材的理论体系,才能给予同学生系统的巩固的科学知识。从卤素到硫氮碳     

银的回收

从化学实验室回收的、含有银的废液,都倒在一个容器中。不从容器中除去沉淀。加入过量的盐酸。仔细搅动容器中的内容物。此时,溶液中的银已转变成沉淀。如铬酸银,这样的银盐沉淀也要转变成难溶性的氯化银。加盐酸的同时,还能从溶于盐酸的,其他各种金属化合物中释出银沉淀来。这些化合物,在合并废液时,包藏了银的沉淀。然后,过滤沉淀。用稀盐酸洗涤,后用水洗涤。将沉淀移至大锥形瓶中,加入过量的,新制的硫化铵或硫     

对化学教师利用报纸帮助教学的小建议

化学和其它学科一样,教师在传授化学知识的同时,必须要对学生进行社会主义思想教育。为完成上述任务,教师除要有正确的政治观点外,还应该随时关心时事,不断充实自己的知识,熟悉我国化学科学和化学工业的发展情况和与化学有关的社会主义建设的情况。而报纸是百科全书,它每天给我们带来很多新知识,是进行政治思想教育取之不尽、用之不竭的源泉。我们如果把每天所看到的材料搜集起来,用在教学上,将会起很大的作用。现在,个人仅在此发表一点粗浅意见,作为参考。我认为,教师在每次看报后,应该把报纸上有关化学的资料,分类的摘录在一个本子上或卡片上。如果教师本人订有报纸,就不必详细摘录,只须像编“索引”一样把题目抄下来,将来需要时再去查报纸即可。这样做不会花费很多时间,而且日积月累,教师手边将有一大批进行政治思想教育的教学参考资料。搜集资料的分类,有多种多样。例如:可以按照教学大纲的章节分类,也可以按工业、农业……等分类。而每一类中又分为国际和国内两小类。我是按照后者分类的。总之,分类方法以教师本人感到方便为宜。教师阅读报纸,搜集资料应以人民日报和本地报纸为主。因为人民日报是全国性的大报纸,消息多,资料丰富;而本地报纸上的材料给学生讲授,学生更会感到特别亲切,加深对家乡的热爱。     

关于蛋白质结构的吡嗪肽链学说的讨论

蛋白质是生命的基础。在自然界中,凡能表现生命现象的物质,都含有蛋白质。目前我们深信,蛋白质是一切生物体中新陈代谢和其他生理机能的体现者。由此可见,蛋白质是一类极重要的物质。我们对蛋白质的认识,直接关连着对生命现象本质的认识。不言而喻,对蛋白质的了解,在应用技术上,尤其是在医学上,亦有极大的价值。     

节省能源的合成化学

我认为我们今天研究化学有三个目的。一是保护环境,二是改善生活,三是节省能源。在这里我们来考虑一下其中的节省能源的问题吧。贵国是资源最丰富的国家之一。但是,我想也在考虑如何有效地利用资源的问题。缺乏资源的日本,更是如此。表1列出了1976年日本消耗石油的情况,总共为二亿三千多万千立升。除了所注明的进口制品以外,都是从进口的原油提炼得到的。日本的石油化学工业是以其中的石脑油做为原料的。做为一名合成化学家,我认为,在最近几十年内,除非有很大的技术革新,否则,合成化学的原料只能依靠石油及其有关气体。煤也是把它变成石油后,做为合成化学的原料来使用才方便。因此,考虑节约石油,就意味着如何巧妙地利用石油以外的东西。     

结合乡土教材进行教学的体会

结合乡土教材进行教学,是党和教育行政部门在本期教学改革中,响亮提出的口号之一。是克服“三脱离”的重要措施之一。但最初感到无法下手,原因是:一方面缺少有关材料,另方面没有办法和经验。另外在思想上有个错误的想法:认为本县无啥可结合,找不到有价值的材料。经过了学习,认识到这正是资产阶级的好高鹜远,不结合实际的腐朽的观点在作怪。思想得到纠正以后,开始行动,边摸索,边总结,对自己也是边提高。从实际教学中,感到结合乡土教材进行教学的提法是正确的,是英明的。现在把我的体     

有机化合物中二种或二种以上卤素共存时的容量測定法

近年来,由于有机化学的飞速发展,化合物类型日益增加。同时存在数种卤素的有机化合物也日益增多。个别卤素的测定方法已不能满足当前工作的需要。直到目前为止,关于同时存在数种卤素的测定方法报导很多,总的来讲,可分为重量法、容量法及仪器分析法三种。早期以重量法居多,它的缺点是耗时长,手续繁。近年来的研究工作则偏重于容量法测定,由于它具有操作迅速、仪器设备简单等优点,经过不断改进,尤其在微量测定的准确度方面有了很大的提高,因此使用较为广泛。随着仪器分析方法的发展,数种卤素同时测定的方法中也应用了电位法、极谱法及光度法等。这些方法虽然具有快速的优点,但在准确度方面,还不能令人满意。显然,结合我国目前实验室的具体条件和多快好省原则,采用容量法是行之有效值得     

如何结合化学教材解决学校粉笔自给

为了加强理论联系实际,结合化学教材、贯彻勤工俭学方针,本期在高三讲完烧石膏后,解决学校粉笔自给。首先与附近手工业白铁小组的铜匠协作铸好两块铜模。用废铜熔铸,翻沙车光。如缺铜可用铝代替;亦可自己制造,先做好木模型。翻沙,向铜匠处买一个大的泥做坩埚,把废铝放进坩埚,在木炭或煤炉里熔融。铝熔点660℃,铜熔点1083℃。因此,用铜需用风箱拉风才能熔铸。再用钢打成六角棱的棒,如粉笔一样大小,下部小,上部稍大的条条。然后把铸好的两块模版钳紧,使转动棱棒滚削光滑即成。再用木材制造一个配有活叶(蝶铰子)能活动打开的木盒,用它套着模版,上面空缺,以备注石膏浆,木盒套着以防止石膏浆的漏失。     

顶空气相色谱法测定果汁中乙醇

果汁中乙醇含量的高低 ,是果汁质量的重要指标。目前国内大多采用国标法测定 ,即重铬酸钾氧化 硫酸亚铁铵滴定法。该法花费时间长 ,条件不易控制。由于果汁一般都比较粘稠 ,因此不能采用直接气相色谱法测定。应用顶空气相色谱法测定果汁中乙醇浓度 ,至今未见国内外文献报道。该法在限定温度条件下 ,高沸点的组分不进柱 ,对色谱柱的污染少 ,从而延长色谱柱的使用寿命。利用本法可以进行自动分析 ,从而节省分析时间 ,尤其适用于成批量样品的测定。本法操作简单 ,条件易于掌握 ,线性范围宽 ,准确度和精密度高。1　试验部分1.1　仪器与试剂ＨＰ…     

Grafting nanocellulose with diethylenetriaminepentaacetic acid and chitosan as additive for enhancing recycled OCC pulp fibres

Cellulose - This paper develops a novel paper additive for effectively recycling old corrugated container (OCC) by functionalizing nanocellulose (NC) with diethylenetriaminepentaacetic acid (DTPA)...     

Polymeric coacervate coating for flame retardant paper

Cellulose - Cellulosic paper (from wood fibers) is a highly flammable material that is used in corrugated carboard, packaging, printing, and construction. While there is significant work focused on...     

Surface anchoring of rodlike molecules on corrugated substrates

We studied the mechanism of surface anchoring of rodlike molecules on substrates with the surfaces corrugated at molecular scale by molecular-dynamics simulation. We constructed a model for substrates that can have anisotoropic topographical patterns such as corrugation. The structural and thermodynamic properties of rodlike molecules on the corrugated surfaces, including the elastic and anchoring properties, were calculated and the influence of the surface structure on the anchoring was discussed. We found that the rodlike molecules are aligned along the grooves of the corrugated surfaces guided by the anisotropic molecular interaction between the molecules and the corrugated surface. The strength of anchoring was found to be increased when the period of corrugation is decreased at molecular level.     

AFM studies of solid-supported lipid bilayers formed at a Au(111) electrode surface using vesicle fusion and a combination of Langmuir-Blodgett and Langmuir-Schaefer techniques

Atomic force microscopy (AFM) has been used to characterize the formation of a phospholipid bilayer composed of 1,2-dimyristyl-sn-glycero-3-phosphocholine (DMPC) at a Au(111) electrode surface. The bilayer was formed by one of two methods: fusion of lamellar vesicles or by the combination of Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) deposition. Results indicate that phospholipid vesicles rapidly adsorb and fuse to form a film at the electrode surface. The resulting film undergoes a very slow structural transformation until a characteristic corrugated phase is formed. Force-distance curve measurements reveal that the thickness of the corrugated phase is consistent with the thickness of a bilayer lipid membrane. The formation of the corrugated phase may be explained by considering the elastic properties of the film and taking into account spontaneous curvature induced by the asymmetric environment of the bilayer, in which one side faces the gold substrate and the other side faces the solution. The effect of temperature and electrode potential on the stability of the corrugated phase has also been described.     

The phase behavior of two-dimensional symmetrical mixtures in a weak external field of square symmetry

Using Monte Carlo simulation methods in the grand canonical and semigrand canonical ensembles, we study the phase behavior of two-dimensional symmetrical binary mixtures of Lennard-Jones particles subjected to a weakly corrugated external field of a square symmetry. It is shown that the both vapor-liquid condensation and demixing transition in the liquid phase are not appreciably affected by a weakly corrugated external field. On the other hand, even a weakly corrugated external field considerably influences the structure of solid phases and the liquid-solid transition. In particular, the solid phases are found to exhibit uniaxially ordered distorted hexagonal structure. The triple point temperature increases with the corrugation of the external field, while the triple point density becomes lower when the surface corrugation increases. The changes in the location of the triple point are shown to lead to the changes of the phase diagram topology. It is also demonstrated that the solid phase undergoes a demixing transition, which is also very slightly affected by the weakly corrugated external potential. The demixing transition in the solid phase is shown to belong to the universality class of the Ising model.     

Mechanics of planar beams focusing on buckling phenomena

A methodology for the analysis of the mechanical behaviour of beams is presented, which relies on the lemma of stroboscopy. This problem traces back to Euler's work. Starting from a discrete model of the shape of the beam, stroboscopy enables us to built a continuous model for the variation of the angular position along the corrugated beam. The angular position is characterised as the solution of a differential equation. The main originality of the work is the study of buckling conditions of corrugated beams.     

Tailored core-shell-shell nanostructures: sandwiching gold nanoparticles between silica cores and tunable silica shells

Size tunable and structure tailored core-shell-shell nanospheres containing silica cores, gold nanoparticle shells, and controlled thicknesses of smooth, corrugated, or porous silica shells over the gold nanoparticles have been synthesized. The synthesis involved the deposition of gold nanoparticles on silica cores, followed by sol-gel processing of tetraethoxysilane (TEOS) or sodium silicate to form dense or porous silica shells, respectively, over the gold nanoparticles. The structures and sizes of the resulting core-shell-shell nanospheres were found to heavily depend on the sizes of the core nanoparticles, the relative population of the gold nanoparticles on each core, and the concentration of TEOS. While a higher TEOS concentration resulted in thicker and more uniform silica shells around individual larger silica cores (approximately > or =250 nm in diameter), the same TEOS concentration resulted in aggregated and twin core-shell-shell nanostructures for smaller silica cores (approximately < or =110 nm in diameter). The thinner silica shells were synthesized by using a lower TEOS concentration. By using sodium silicate (Ung et al. J. Phys. Chem. B 1999, 103, 6770), the porous silica shells were synthesized. Controlled chemical etching of the core-shell-shell nanoparticles with an aqueous KCN solution resulted in corrugated silica shells around the gold nanoparticles or corrugated silica nanospheres with few or no gold nanoparticles. This has allowed synthesis of new types of core-shell-shell nanoparticles with tailored corrugated shells. The nanoporous silica shells provided accessible structures to the embedded metal nanoparticles as observed from the electrochemical response of the gold nanoparticles.     

Progressive failure numerical simulation and experimental verification of carbon-fiber composite corrugated beams under dynamic impact

To explore the axial impact energy absorption capacity of bidirectional carbon pre-impregnated (prepreg) composite corrugated beams, a solid 3D finite element model with different trigger mechanism settings and different ply designs was established. Numerical simulation of dynamic impact was performed on the model. An in-plane damage model considering shear failure was created based on continuum damage mechanics and Hashin's criteria, and a stiffness degradation model of damage failure for G803/5224 is proposed. The cohesive zone model is used and the bilinear traction-separation constitutive model is considered to simulate inter-laminar delamination failure, thereby accurately reflecting the anisotropic progressive damage characteristics of bidirectional carbon-fiber prepreg composite corrugated beams. The results show that progressive failure and damage occur under impact loading of corrugated beams. The energy-absorbing load-displacement curve and specific energy absorption were obtained through simulation. Simulation results were validated by comparison with test results. With the maximum relative error of its average crushing load less than 11%, the damage morphology and test results of the beam has improved in uniformity. Furthermore, the validity of 3D finite element models considering inter-laminar delamination damage has been validated.     

Reduced density matrix quantum approach for particle trapping and sticking on corrugated moving surfaces

A short time propagation algorithm for the reduced density matrix is derived to model the interaction of a quantum particle with a moving corrugated surface. The algorithm includes dissipative terms, which can be derived directly from the full Hamiltonian. The scattering of He from a corrugated Cu surface is examined as a function of incident energy and angle and the temperature of the substrate, with a focus on the nature of trapping. It is found that corrugation can make a significant contribution to trapping, even on a metal surface. Energy exchange with the phonons is shown to significantly modify the nature of diffraction mediated selective adsorption.     

化学混凝法处理废纸制浆废水的研究

在对瓦楞箱板纸废纸制浆废水的特性作了较系统的分析研究的基础上 ,采用自制的混凝剂LPAS及商品絮凝剂聚合氯化铝PAC ,研究了二者的最佳使用条件与对该废水的处理效果 ,结果表明 :混凝剂LPAS比商品絮凝剂PAC对该废水有更好的处理效果 ,当混凝剂LPAS用量为1 50mg/L时 ,废水CODcr、TSS的去除率分别达 71 .8%和 83.6 % ,添加助凝剂FO4 2 4 0可使絮层的沉降速度加快。