无公害型砂粘结剂性能研究

本文以木薯粉为原料,从无公害出发,探索一种新型粘结剂的工艺性能。测试多种因素对该粘结剂干拉强度的影响。结果表明,Ｂ型粘结剂具备了制作型砂应有的性能。可望在锋生产中取代桐油及合脂油。     

3M Adper Prompt自酸蚀粘结剂治疗牙本质过敏的近期疗效观察

目的了解3MAdperPrompt治疗牙本质过敏的疗效。方法于2004年11月-2005年3月间采用3MAdperPrompt自酸蚀粘结剂与75%氟化钠甘油糊剂给左右对称的同名牙进行脱敏对比观察。将确诊为牙本质过敏症的42例,共51对牙,随机分为两组。治疗组用3MAdperPrompt粘结剂,对照组用75%氟化钠甘油,在统一的疗效标准下进行即刻、一周、1个月、3个月四时段的疗效对比。结果第一,二时段的疗效二者无显著性差异。而第三,四时段的疗效3MAdperPrompt明显优于氟化钠甘油糊剂。结论3MAdperPrompt是一种比较理想的脱敏剂。     

内部结构可控的大体积三维细胞支架制备研究

目的：研究一种可以控制三维细胞支架内部孔隙结构的实验技术,用于制备孔隙结构可控的三维细胞支架,以满足组织工程对支架孔隙结构的要求。方法：均匀混合粘结剂与致孔剂,在离心力作用下去除混合物中多余的粘结剂,应用溶剂浇注/颗粒沥析方法制备三维细胞支架。结果：致孔剂粘结块的结构非常均匀,粘结程度可以通过实验条件控制。例如,直径为100~220μm的致孔剂,在离心力为161g,粘结剂浓度分别为20％和40％时,颗粒间粘结程度分别为33.78±556 (134)μm和42.89±5.87 (132) μm。并且,利用该技术制备的三维多孔支架,其内部孔隙大小取决于致孔剂颗粒大小,孔隙间的通道直径取决于致孔剂的粘结程度,即离心粘结与溶剂浇注/颗粒沥析技术相结合,能够方便地控制三维支架的孔隙结构。例如,当粘结程度为33.78±556 (134) μm时,支架的通道直径为33.34±5.21(12)μm,两者之间无显著差异。 结论：利用离心粘结与溶剂浇注/颗粒沥析技术结合,获得了孔隙呈球形、孔隙间完全连通的、结构均匀的大体积三维细胞支架,并且支架的孔隙以及孔隙间通道大小均可以实现人为控制。     

细菌藻酸盐研究进展

细菌藻酸盐研究进展邱立友（河南农业大学植保系,郑州４５０００２）１９世纪８０年代初从海藻中分离出藻酸盐（ａｌｇｉｎａｔｅ）以来,数十年间,藻酸盐在食品、纺织、印刷和制药等领域中广泛用作胶化剂或粘结剂。用于提取藻酸盐的海藻主要有巨藻（Ｍａｃｒｏｏｃｙｓ...     

残根残冠的桩核修复

桩核冠是临床上保存残根残冠的修复方法之一,按种类可分为金属桩和非金属桩两大类。影响桩冠固位的因素很多,主要包括核的材料、桩的表面形态、长度、直径、箍结构、粘结剂、桩核预备时机及桩在牙列中的位置。只有掌握了这些内容,恰当的选择和利用,才能保证临床修复效果。     

加工利用四川柔毛冷杉树脂的采集与加工

冷杉树脂加工制成的热熔性树脂胶称冷松胶。最初是由加拿大香胶枞树(Abies Balsamea Mill。)的树脂加工而成,所以又称加拿大胶。冷杉胶具有很高的光学一致性,如极大的透明度,与光学玻璃相接近的折光指数,有合适的线膨胀系数,不结晶,无毒,有一定的胶合能力等。因此,在光学仪器制造工业上被用作光学零件的胶合剂,同时也是地质磨片和生物切片使用的粘结剂,照像印刷制板的胶合,雕刻工艺美术的胶粘剂等。     

贻贝足腺细胞的超强度粘液

贻贝足腺细胞能分泌出超强度粘液 (ｓｕ ｐｅｒｇｌｕｅ) ,该粘液遇海水后即变成贝壳素性质的足丝 ,用以固着在附着物上。因其粘合力及防水性能极强 ,是现有任何粘合剂均无法比拟的 ,故而引起了学者们的极大兴趣[1,2 ] 。贻贝的超强度粘液具有非常优秀的抗水性能 ,且凝固速度极快 ,因此也可被用来制作水下密封胶、防腐剂和粘合剂 ,如在国防和海洋工程领域可直接用作船舶、潜艇和海水养殖设备的防水防附剂和粘结剂 ,可以替代螺丝和铆焊等常规固定手段。此外 ,贻贝足腺细胞所分泌的粘液蛋白对细胞没有毒害作用 ,也不引起人体产生免疫反应 ,因…     

三种粘结剂用于纵折牙粘结的微渗漏研究

目的观察三种粘结材料的封闭性能,为折裂牙选择合适的粘结材料提供试验依据。方法选用健康前磨牙30颗,随机分为3组,制备成后牙纵折模型,分别用Clearfil SE Bond／AP—X（A组）、Super—Bond C＆B（B组）,Single Bond／F2000 Cmpomer（C组）进行粘结,在0．5％亚甲基蓝溶液中染色72h后,在电镜下观察染料渗透深度。结果扫描电镜下观察各组标本的粘结界面均有染料渗入,经单因素方差分析,A组与B组、C组有显著性差异,B组与C组之间无显著性差异。结论Clearfil SE Bond的封闭性能优于其它两组,但三种粘结剂均无法避免微渗漏的发生。     

石膏模型的修补

石膏模型不慎跌坏了 ,假若粉碎程度不大 ,也可以修补。这需要将跌断的小块部分用粘结剂在断面处拼凑粘结起来。待干后 ,将调好的石膏浆用小刀将小块缺损部分修平。石膏浆的调法是 ,取半碗水 ,把热石膏粉撒入水中 ,待石膏粉全部沉淀后轻轻摇动碗 ,倒出多余的水 ,这时石膏和水的比例正好合乎要求。石膏浆要随配随用 ,修补要迅速 ,否则 ,时间长就结成块 ,不好用了。如果原模型涂有色彩 ,可在修补处加色。做法是 ,先在修补处用粗沙纸磨光滑 ,然后用胶水加白粉涂刷。待干后用油画笔调好相应的油画色进行着色。有些陶器模型也可用上法进行修补 ,在…     

三种脱敏药物封闭牙本质小管的扫描电镜观察

观察3M Singlebond~(TM) Universal自酸蚀粘结剂堵塞牙本质小管的效果,为治疗牙本质过敏提供理论依据。收集新鲜的离体第三磨牙42颗,制备成牙本质敏感症模型后随机分为空白对照组(n=6)、3M SinglebondTMUniversal组(n=12)、极固宁组(n=12)、高露洁专效抗敏牙膏组(n=12)。从涂布脱敏剂的3组中各随机抽取6个样本进行刷牙实验。分析所有分组牙本质小管的堵塞效果,并采用SPSS17.0数据分析系统对结果进行分析。从结果可以看出空白对照组牙本质小管完全开放,3M Singlebond~(TM) Universal、极固宁、高露洁抗敏牙膏均能有效封闭牙本质小管,3M Singlebond~(TM) Universal的封闭效果最佳。经过刷牙实验3M SinglebondTMUniversal仍具有较好的牙本质小管封闭效果,而脱敏牙膏组有大量牙本质小管再次开放。这说明3种脱敏剂都具有良好的牙本质小管封闭效果,3M Singlebond~(TM) Universal的封闭性和抗磨耗性最佳。     

Development of environmentally friendly coatings and paints using medium-chain-length poly(3-hydroxyalkanoates) as the polymer binder.

Unsaturated medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHAs) produced by Pseudomonas putida from linseed oil fatty acids (LOFA) and tall oil fatty acids (TOFA), were used as the polymer binder in the formulation of high solid alkyd-like paints. The relatively high concentration of unsaturated alkyl side chains incorporated into the PHA resins resulted in oxidative drying PHA paints having excellent coating properties. The homogeneously pigmented PHA coatings yielded high-gloss, smooth and strong films upon curing and showed an excellent flexibility, a good adhesion to different substrates, cohesive film properties and resistance to chipping.     

Deinking of soy bean oil based ink printed paper with lipases and a neutral surfactant

A screening of different strains of bacteria for the production of lipases which degrade the soy bean oil based binder component of newsprint ink was performed. Three strains were found to be efficient lipase producers and were selected for further investigations. The pH optimum, temperature stability and the optimum enzyme concentrations for the deinking of recovered paper printed with soy bean oil based ink were determined and compared with a commercially available porcine pancreas lipase preparation. A lipase preparation from Pseudomonas aeruginosa with a pH optimum and temperature stability suitable for an application in a deinking process and with a high deinking efficiency in combination with a neutral surfactant could be identified. The deinking effect of the lipases was caused by a partial degradation of the binder of the soy bean oil based inks thereby releasing the ink particles from the paper.     

Production of granular activated carbons from select agricultural by-products and evaluation of their physical,chemical and adsorption properties

Representative samples of soft, low density, group 1 (rice straw, rice hulls, sugarcane bagasse) and hard, high density, group 2 agricultural by-products (pecan shells) were converted into granular activated carbons (GACs). GACs were produced from group 1 and 2 materials by physical activation or from group 2 materials by chemical activation. Carbons were evaluated for their physical (hardness, bulk density), chemical (ash, conductivity, pH), surface (total surface area), and adsorption properties (molasses color removal, sugar decolorization) and compared with two commercial reference carbons. The results show that the type of by-product, binder, and activation method determine the properties of GACs. Regardless of the binder, sugarcane bagasse showed a better potential than rice straw or rice hulls as precursor of GACs with the desirable properties of a sugar decolorizing carbon. Pecan shells produced GACs that were closest to the reference carbons in terms of all the properties investigated.     

Genetics of sulfate transport by Salmonella typhimurium

Sixty-four mutants were isolated from the LT-2 wild-type strain of Salmonella typhimurium by selecting for chromate resistance. The majority of lesions were shown to lie in the cysA gene. (i) The mutants cannot take up sulfate, a finding which verifies the role of cysA in sulfate transport. In addition, 52 sulfate-transport mutants isolated without chromate selection were defective in the cysA gene. (ii) Most had less than 25% of the binding activity of the wild-type strain. (iii) Most had normal sulfite reductase (H(2)S-nicotinamide adenine dinucleotide phosphate oxidoreductase, EC 1.8.1.2) activity. (iv) Their sulfate-binding protein (binder) appears electrophoretically and immunologically normal. (v) Amber cysA mutants also make apparently normal binder in small amounts. (vi) All classical cysA mutants tested, including two with long deletions, had normal binding activity. From these observations, it is suggested that the cysA gene does not code for the binder. But many mutations in this gene reduce the binding activity in some unknown way. Other mutants, identified as cysB mutants, had neither binding nor uptake activities and their sulfite reductase activities were similarly reduced, thus confirming the regulatory role of the cysB gene. When binder was detectable, it had wild-type properties. No mutations in the binder gene were found among more than 100 mutants examined. Thus, sulfate binding has not been established as a part of sulfate transport. However, the production of binder is intimately connected with cysA, the established sulfate transport gene, and is regulated by the same mechanism that regulates both transport and the rest of the cysteine biosynthetic pathway.     

Properties of progestin-binding protein in benign hypertrophic human prostate

RU 27987 is a new ligand for progesterone receptor and binds in high affinity to nuclei of target tissues of progesterone. Using this compound, progestin-binding components in the benign hypertrophic human prostate were studied, and compared with those examined with R 5020, a conventional ligand, in the study of progesterone receptor. In cytosols, the binding affinity of RU 27987 was higher than that of R 5020, and the number of maximum binding sites for RU 27987 seemed to be large but correlated well with those of R 5020. The binder for RU 27987 sedimented at 8.6 S, and the binding was specific to progestational steroids, indicating that binding properties of this binder in the cytosols are identical to those for R 5020. Although there was no binding with R 5020 in the nuclear extract, a small amount of specific binding with RU 27987 was detected. However, the cytosol bound with RU 27987 was not retained in DNA Sepharose and no specific binder for RU 27987 in the nuclear extract was observed in a sucrose density gradient centrifugation. From these observations, it was assumed that the nuclear binding observed was attributable to contamination of the cytosolic binder. The results obtained in the present study suggest that the progestin-binding component in the benign prostatic hypertrophy is not the progesterone receptor but a high affinity binder for progestins whose physiological role is not clear at present.     

Polyesters Based on Linoleic Acid for Biolubricant Basestocks: Low-Temperature,Tribological and Rheological Properties

Presently, plant oils which contain high percentage of linoleic acid 1 are perceived to be a viable alternative to mineral oil for biolubricant applications due to their biodegradability and technical properties. In order to get biodegradable lubricant, triester derivatives compounds (1–5) were synthesized and characterized. The processes involved were monoepoxidation of linoleic acid 2, oxirane ring opening 3, esterification 4 and acylation 5. The structures of the products were confirmed by FTIR, ¹H and ¹³C-NMR and LC-MS. The results that showed lowest temperature properties were obtained for triester 5, with a pour point value (PP) of -73°C, highest onset temperature (260°C) and lowest volatility at 0.30%. Viscosity index (VI) increased for the ester’s synthetic compounds (2, 3, 4, 5), while the PP decreased. This behavior is the result of the increase of the chain length of the branching agents. Triester based linoleic acid has improved properties such as low-temperature and tribological properties. These results will make it feasible for plant oil to be used for biolubricants, fuels in chain saws, transmission oil and brake fluid.     

Diffusion and interaction mechanism of rejuvenating agent with virgin and recycled asphalt binder: a molecular dynamics study

The quality of asphalt binder recycling is largely dependent on molecular diffusion between virgin asphalt binder, aged asphalt binder, and rejuvenator. In this study, molecular dynamics (MD) simulations were used to study diffusion and interaction mechanism of rejuvenating agent in recycled asphalt binder. The diffusion process of rejuvenator into virgin and aged asphalt binder was studied using a three-layered model. A mixture model of virgin and aged asphalt binder was built to evaluate the effect of rejuvenator on the molecular structure of asphalt binder, such as nanoaggregate behaviour and translational mobility. The simulation results of the layered model suggest that rejuvenator may improve blending efficiency of virgin and aged asphalt binder depending on temperature. The calculated inter-diffusion coefficients indicate that the rejuvenator diffuses faster into virgin asphalt binder than aged asphalt binder. The radial distribution functions of asphaltene, resin, and aromatic pairs show that rejuvenator causes the molecular structures of virgin and aged asphalt binder more similar to that of virgin asphalt binder. The rejuvenator reduces the self-association trends of asphaltene molecules, but saturates from local aggregation inside the rejuvenated asphalt binder. On the other hand, rejuvenator increases translational mobility of saturate, aromatic, resin and asphaltene fractions.     

New woody and ambery notes from cedarwood and turpentine oil

The development of a new product in the chemical industry is still driven by needs like technical properties, price/performance ratio, biodegradability, or product safety. However, in terms of improving more and more on ecological criteria, summarized under such catchphrases as sustainable development or green chemistry, another important aspect is to use renewable resources as starting materials. This is not significantly new in fragrance chemistry, and there are a lot of raw materials in the perfume oils that are derived from molecules of renewable resources. Two commonly used materials are: longifolene (from turpentine oil) and cedrene (from cedarwood oil). These compounds are very suitable for the synthesis of woody and ambery notes, and even though it seemed that all possibilities were exhausted, it is actually still feasible to discover new molecules with excellent olfactory properties such as Ambrocenide (50a), which is available in three steps from alpha-cedrene. Some of these molecules will be treated in this review, both with respect to synthesis as well as structural and sensory aspects.     

Investigation of a 2-step agglomeration process performed in a rotary processor using polyethylene glycol solutions as the primary binder liquid

The purpose of this research was to investigate the use of polyethylene glycol (PEG) solutions as the primary binder liquid in a 2-step agglomeration process performed in a rotary processor and characterize the resulting granules and their tableting characteristics. This was done by granulation of binary mixtures of microcrystalline cellulose (MCC) and either lactose, calcium phosphate, acetaminophen, or theophylline, in a 1∶3 ratio, using a 50% (wt/wt) aqueous solution of PEG and water as the binder liquid. Formulations containing lactose were agglomerated using 5 different amounts of the PEG binder solution, giving rise to a PEG content in the range of 6% to 43% (wt/wt). The process outcome was characterized according to adhesion, yield, and water requirement, and the prepared granules were characterized according to size, size distribution, and flow properties as well as tableting properties. The agglomeration of all mixtures resulted in high yields of free-flowing agglomerates and gave rise to good reproducibility of the investigated agglomerate characteristics. The process allowed for the incorporation of 42.5% (wt/wt) PEG, which is higher than the percentage of PEG reported for other equipment. Tables of sufficient strength could be prepared with all investigated excipients using 20% wt/wt PEG; higher PEG contents gave rise to adhesion and prolonged disintegration. In conclusion, agglomeration in a torque-controlled rotary processor using solutions of PEG as the primary binder liquid was found to be a robust process, suitable for the incorporation of high contents of PEG and/or drug compounds.     

Activated carbon briquettes from biomass materials

Disposal of biomass wastes, produced in different agricultural activities, is frequently an environmental problem. A solution for such situation is the recycling of these residues for the production of activated carbon, an adsorbent which has several applications, for instance in the elimination of contaminants. For some uses, high mechanical strength and good adsorption characteristics are required. To achieve this, carbonaceous materials are conformed as pellets or briquettes, in a process that involves mixing and pressing of char with adhesive materials prior to activation. In this work, the influence of the operation conditions on the mechanical and surface properties of briquettes was studied. Eucalyptus wood and rice husk from Uruguay were used as lignocellulosic raw materials, and concentrated grape must from Cuyo Region-Argentina, as a binder. Different wood:rice and solid:binder ratios were used to prepare briquettes in order to study their influence on mechanical and surface properties of the final products.