降焦减害滤嘴添加剂的研究进展

滤嘴具有降焦减害的作用,滤嘴添加剂可针对性地降低主流烟气中的有害成分.对滤嘴添加剂进行分类综述,简述了活性炭、壳聚糖、茶质、中草药、生物材料、分子筛、纳米材料类添加剂的研究进展,及其在烤烟降焦减害中的作用,并对进一步研究滤嘴添加剂本身在抽吸过程中是否会产生有害物质提出建议.     

Microstructure of Polymers by Tritium Autoradiography

Polystyrene, polypropylene, and polyethylene, containing tritiumlabeled additives and crystallized in thin films, were examined with autoradiographic stripping film. In the structures formed by isotactic polystyrene, tritiated atactic polymer concentrated in specific patterns in the outer regions. Polypropylene spherulites showed marked differences in the distribution of the tritiated additive, dilauryl thiodipropionate, whenever their optical properties also differed. Autoradiographs of polyethylene spherulites containing low molecular weight tritiated polyethylene exhibited concentric ring patterns similar to those observed on viewing the polymer film in a polarizing microscope.     

添加剂在不锈钢化学着色中的作用

通过试验研究了添加剂在不锈钢化学着色中的作用。结果表明:同一电位差下,颜色基本一致,随着三种添加剂(ZnSO4、MnSO4、(NH4)6Mo7O24.4H2O)用量的加大,颜色向长波方向移动;ZnSO4对着色电位起稳定作用,不仅便于记录瞬时着色电位,而且可使颜色易于控制,实现良好的重现性;MnSO4不仅起加速作用,而且添加适量可以显著提高着色膜的光亮度;(NH4)6Mo7O24.4H2O不仅起光亮作用,而且能明显提高着色膜的耐磨性。     

Synthesis of two-dimensional polymers

A synthetic pathway is described to construct "in bulk" two-dimensional (2D) polymers shaped as molecular sheets. A chiral oligomeric precursor is used that contains two reactive sites, a polymerizable group at one terminus and a reactive stereogenic center near the middle of the molecule. The bulk reaction yields bilayer 2D polymers of molecular weight in the order of millions and a monodisperse thickness of 50.2 angstroms. The 2D molecular objects form through molecular recognition by the oligomers, which self-organize into layers that place the reactive groups within specific planes. The oligomers become catenated by two different stitching reactions involving the reactive sites. At room temperature, stacks of these molecular objects can organize as single crystals and at higher temperatures melt into smectic liquid crystals. Nonlinear optical experiments reveal that solid films containing the 2D polymers form structures that are thermally and temporally more stable than those containing analogous 1D polymers. This observation suggests that the transformation of common polymers from a 1D to a 2D architecture may produce generations of organic materials with improved properties.     

Divalent metal nanoparticles

Nanoparticles can be used as the building blocks for materials such as supracrystals or ionic liquids. However, they lack the ability to bond along specific directions as atoms and molecules do. We report a simple method to place target molecules specifically at two diametrically opposed positions in the molecular coating of metal nanoparticles. The approach is based on the functionalization of the polar singularities that must form when a curved surface is coated with ordered monolayers, such as a phase-separated mixture of ligands. The molecules placed at these polar defects have been used as chemical handles to form nanoparticle chains that in turn can generate self-standing films.     

不同添加剂对拉伸膜裹包苜蓿青贮的影响

【目的】为了探讨不同添加剂、不同贮藏时间苜蓿青贮的发酵品质与养分动态。【方法】设对照、添加甲酸或绿汁发酵液处理，鲜苜蓿整株打圆捆后，拉伸膜裹包青贮，取样后进行分析。【结果】添加甲酸或绿汁发酵液均可以改善苜蓿青贮的发酵品质，青贮pH极显著下降（P<0.01），而且乳酸含量增加(P<0.05)，氨氮含量减少(P<0.05)，而且随着贮藏时间延长，添加剂处理效果更佳；不同添加剂处理对苜蓿青贮的CP、NDF、ADF、非蛋白氮、酸性洗涤不溶性氮含量影响不大，而贮藏时间对各营养成分含量影响较大。【结论】秋季最后一茬苜蓿青贮时，添加甲酸或绿汁发酵液，可以延长苜蓿青贮的贮藏时间，从而保证苜蓿青贮的均衡供应。     

添加剂在减少畜禽粪便污染中的应用与发展前景

大量文献表明,酸化剂、吸附剂、尿酶抑制剂能减少氨的挥发和恶臭物质的排放,但这些添加剂仅能提供短期抑制,必须反复添加才能维持其作用。微生物制剂能利用粪便中未消化的营养物质繁殖,但如果不很好地了解畜禽粪便中微生物的发酵活动,该添加剂的作用效果值得怀疑。通过综述添加剂在畜禽粪便污染治理当中的应用,指出今后应开展如下工作:建立标准化程序评估添加剂的有效性;研究不同添加剂安全、经济、有效的作用剂量;评估在畜禽舍内使用添加剂后对畜禽、饲养员健康状况的影响;评估使用添加剂处理后的畜禽粪便在还田时对农业生态系统的影响。     

高速钢热处理工艺与耐磨性关系的研究

通过对高速钢(W18Cr4V)热处理工艺与其磨损特性关系的实验研究,即选择不同的淬火温度,回火温度、回火次数等条件,探讨了摩擦速度,材料硬度、残留碳化物及残余奥氏体对磨损量的影响。文中指出在摩擦速度小于1m/s时(低速度区內),耐磨性依赖于材料的硬度,硬度愈高,耐磨性愈好。而在摩擦速度大于1m/s时(高速度区內),则硬度高、耐磨性好的规律并不完全成立。同时说明适当降低淬火温度,提高回火温度(550℃—570℃),对提高冷作模具钢的耐磨性具有一定的效果。     

Laser ablation and the production of polymer films

The formation of high-quality thin films of polytetrafluoroethylene (PTFE) is important in many applications ranging from material reinforcement to molecular electronics. Laser ablation, a technique widely used to deposit a variety of inorganic materials, can also be used as a simple and highly versatile method for forming thin polymer films. The data presented show that PTFE films can be produced on various supports by the evaporation of a solid PTFE target with a pulsed ultraviolet laser. The composition of the ablation plume suggests that PTFE ablation and subsequent film formation occur by way of a laser-induced pyrolitic decomposition with subsequent repolymerization. The polymer films produced by this method are composed of amorphous and highly crystalline regions, the latter being predominantly in a chain-folded configuration with the molecular axis aligned parallel to the substrate surface.     

Oriented 2D covalent organic framework thin films on single-layer graphene

Covalent organic frameworks (COFs), in which molecular building blocks form robust microporous networks, are usually synthesized as insoluble and unprocessable powders. We have grown two-dimensional (2D) COF films on single-layer graphene (SLG) under operationally simple solvothermal conditions. The layered films stack normal to the SLG surface and show improved crystallinity compared with COF powders. We used SLG surfaces supported on copper, silicon carbide, and transparent fused silica (SiO(2)) substrates, enabling optical spectroscopy of COFs in transmission mode. Three chemically distinct COF films grown on SLG exhibit similar vertical alignment and long-range order, and two of these are of interest for organic electronic devices for which thin-film formation is a prerequisite for characterizing their optoelectronic properties.     

中草药添加剂对肉鸡及育肥猪的饲喂效果试验

为了探讨中草药添加剂对肉鸡和育肥猪生产性能的影响,试验选取同场同天入孵出壳的健康艾维茵健康肉仔鸡680只,自繁自养、日龄相同、体重接近的杜长大三元杂交育肥猪270头,分别随机分成5组,其中对照组1个,基础日粮中不添加中草药添加剂,试验组4个,分别添加不同水平中草药添加剂(肉鸡2.0%、2.5%、3.0%、3.5%,育肥猪0.40%、0.45%、0.50%、0.55%),测定生产性能等指标,分析肉鸡、育肥猪使用中草药添加剂的实际效果。结果表明:与对照组相比,饲料中使用中草药添加剂后,可明显提高肉鸡、育肥猪日增重、饲料报酬和经济效益,降低发病率和死亡率,并以肉鸡添加2.5%的中草药添加剂、育肥猪添加0.50%的中草药添加剂饲喂效果最好。说明中草药添加剂对肉鸡和育肥猪的生产性能具有良好的作用,可明显提高经济效益。     

可食性包装膜及其制备工艺优化研究

塑料包装带来的环境污染问题引起了食品包装研究人员的重视,可食性包装膜由于其绿色安全,成本低廉等特性成为近年来取代塑料包装的研究热点之一。可食性包装膜主要采用可食性生物聚合物和食品级添加剂制成,主要通过阻止气体、水气和溶质的迁移,添加抗氧化、抑菌性物质等提高食品质量,保护食品免受物理、化学和生物的破坏,从而延长食品货架期。对关于可食性包装膜的介绍、分类、制备工艺优化等方面的研究进行综述,为可食性包装膜的应用提供参考。     

微塑料的环境行为及其生态毒性研究进展

微塑料污染已经成为全球关注的环境问题。本文对不同环境介质中微塑料的来源、迁移、分布特征及其对生物体的毒性效应等方面的研究现状进行了系统的总结和评述。微塑料的来源主要包括直接进入到环境中的初生微塑料和大块塑料破裂、分解形成的次生微塑料,其可在大气、水体(淡水和海洋)和陆地环境之间进行迁移。需建立统一的微塑料样品采集、分离和鉴定方法,并结合准确高效的溯源分析技术,进一步探索其环境行为与归趋。微塑料(含自身的添加剂)被生物摄取后会造成物理损伤、引发生物体的行为、生理学和分子学反应,并可能与其他污染物形成复合污染,产生联合毒性效应。通过同位素示踪与分子生物学新技术的联用,重点研究微塑料的生物累积和在食物链中的传递效应,尤其是对人体健康的潜在威胁,以期为微塑料污染的生态风险评估提供理论依据。     

添加剂对纤维素酶耐温性的影响

为提高纤维素酶在较高温度条件下的耐温性,考察5种添加剂（聚乙二醇、甘油、木糖醇、氯化钙、黄原胶）对纤维素酶酶活的影响。结果表明,在58℃、保存24 h条件下,聚乙二醇、甘油、木糖醇、黄原胶对纤维素酶酶活有保护效应,较未添加时的相对酶活有所增加。木糖醇的保护效应最为显著,相对酶活由0.59提高到0.94;而氯化钙对酶活有抑制效应,相对酶活由0.59降低为0.49。     

蝴蝶兰种子胚组织培养优化技术研究

以蝴蝶兰种子胚为外植体,探讨了不同采收期、不同培养基以及在培养基中添加多种附加物对原球茎形成和成苗的影响。结果表明:授粉后120~150 d的成熟种子胚适宜于组织培养,以花宝1号为基本培养基,附加椰子汁、香蕉、土豆汁能很好地诱导原球茎,诱导率达95%以上。添加有机附加物对不同花色的蝴蝶兰品种的培养效果不同,不添加植物生长调节剂也有利于种子萌发。用花多多4号3~4 g/L+Tryptone 2~2.5 g/L+1/3MS+6BA 1.0 mg/L+NAA 0.02 mg/L+CW 100 g/L+AC 0.5~1.0 g/L有利于原球体和幼苗的生长,成苗率达90%以上。     

含精油可食膜在肉及肉制品保藏中的应用

可食膜因安全、无污染和制作简单等优点应用广泛,植物精油具有较高抗菌和抗氧化活性,可减少或替代合成食品添加剂,将精油加入可食膜后应用于肉及肉制品保藏,防腐保鲜效果显著提高。文章从含精油可食膜概述、分类、添加精油对可食膜性能的影响及其在肉及肉制品保鲜贮藏领域应用等方面展开综述,阐述问题并展望发展前景,以期对含精油可食膜在肉及肉制品领域中研究应用提供理论参考。     

含硫添加剂对猪粪堆肥过程甲烷与臭气排放的影响

为探寻合适的含硫添加剂,有效控制堆肥过程中甲烷和臭气的排放,以磷石膏（PG）、过磷酸钙（SP）、硫酸钠（NS）为添加剂,采用强制通风曝气的60 L桶状发酵罐,探究不同含硫添加剂对于猪粪堆肥过程中气体排放的影响。结果表明：添加堆肥原始物料鲜质量2%的PG、2%的SP、1.2%的NS处理分别能减少50.8%、43.3%、46.6%的甲烷排放;PG和SP处理能减少40.6%和37.2%的氨气挥发,NS处理减少了20.0%的氨气挥发;PG与SP处理对硫化氢气体没有产生明显的抑制作用,而NS处理的硫化氢排放量为对照（无添加剂）处理的3.8倍,且NS处理堆肥结束后种子发芽率仅为41.3%。研究表明,1.2%的NS处理不适合臭气减排,而添加2%的PG以及2%的SP等低硫添加剂较为适宜。     

Dynamic properties of molecularly thin liquid films

An experimental technique is described for simultaneously measuring the static and dynamic interactions of very thin liquid films between two surfaces as they are moved normally or laterally relative to each other. Film thickness can be measured and controlled to 1 angstrom. Initial results are presented of the transition in the physical properties of liquid films only one molecular layer thick to thicker films whose properties are practically indistinguishable from the bulk. In particular, the results show that two molecularly smooth surfaces, when close together in simple liquids, slide (shear) past each other while separated by a discrete number of molecular layers, and that the frictional force is "quantized" with the number of layers.     

1个含有SDR结构域PKS/NRPS基因的克隆

聚酮和非核糖体多肽的复合化合物具有独特的生理活性,它们由聚酮合酶/非核糖体肽合成酶（PKS/NRPS）催化合成。目前球孢白僵菌Beauveria bassiana中含SDR结构域的PKS/NRPS酶的生物合成机制尚不清楚,采用基因挖掘技术从球孢白僵菌基因组中分离得到1个PKS/NRPS基因（命名Bbpks2）,利用生物信息学分析对其功能进行预测并检测该基因在以6.0 g·L-1麦芽提取物和3.0 g·L-1酵母提取物为基本氮源培养基,7种碳源添加物和以1.8 g·L-1麦芽糖和6.0 g·L-1葡萄糖为基本碳源培养基,4种氮源添加物培养基上的具体表达情况,其中每种添加物含量为4.0 g·L-1。结果显示:Bbpks2基因长度为12 051 bp,编码4 016个氨基酸;其结构域组织顺序为KS-AT-DH-MT-KR-ACP-C-A-PP-SDR,是一种含有SDR结构域的PKS/NRPS;系统进化分析发现,BbPKS2与球孢白僵菌JEF007菌株（PMB64475.1）、头状虫草Tolypocladium capitatum（PNY25600.1）等的PKS/NRPS蛋白聚在同个分支中,可能参与一种聚酮/非核糖体多肽类化合物的生物合成;比较不同氮源、碳源添加物对Bbpks2基因表达的影响,发现该基因在添加了乳糖的培养基上的表达量是其他碳源添加物的3.4倍以上,添加了牛肉浸粉的培养基上表达量是其他氮源添加物的1.3倍以上。该研究为下一步通过异源表达鉴定Bbpks2基因的具体功能,及其调控机理研究和基因资源利用奠定基础。     

Mussel-inspired surface chemistry for multifunctional coatings

We report a method to form multifunctional polymer coatings through simple dip-coating of objects in an aqueous solution of dopamine. Inspired by the composition of adhesive proteins in mussels, we used dopamine self-polymerization to form thin, surface-adherent polydopamine films onto a wide range of inorganic and organic materials, including noble metals, oxides, polymers, semiconductors, and ceramics. Secondary reactions can be used to create a variety of ad-layers, including self-assembled monolayers through deposition of long-chain molecular building blocks, metal films by electroless metallization, and bioinert and bioactive surfaces via grafting of macromolecules.