931 resultados para Preparation of polyuerthanes


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A process is described for the utilisation of mussel shell wastes by their conversion into lime, which may be used for white washing and plastering.

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Studies to find out the suitability of tuna red meat for preparation of wafers have indicated that the red meat as such is not a good raw material for the production of wafers. The wafers obtained had poor organoleptic quality and characteristic tuna red meat flavour unacceptable to consumers. Attempts to prepare the wafers with the red meat mixed with the meat of barracuda in varying proportions showed that the mixture of red meat and barracuda meat in the ratio 1:3 gives a product having excellent physical properties and good swelling characteristics. The overall organoleptic quality of these wafers was very much comparable to the wafers produced from other quality fish. Increasing the proportion of red meat not only affects the overall appearance of the product but a1so imparts the red meat taste to the product.

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A simple and cheap process for the preservation of mussel meat by marinading is described. The method involves blanching the mussel meat shucked from depurated live mussels in 3% boiling sodium chloride solution for 5 min followed by preserving it in a solution containing 3% acetic acid and 3% sodium chloride. The product stored in closed glass jars has a storage life of approximately 16 weeks at room temperature (23-30°C), after which the quality began to deteriorate. Texture of the meat is least affected and closely resembles that of the fresh meat.

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The present work gives some information on use of shrimp wastes of processing industries of Bangladesh in preparation of valuable chitin products such as glucosamine hydrochloride.

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The report presents; terms of reference; work progress; surveys of shark fishers and traders; shark biodiversity survey; and a National Plan of Action (NPOA) for conservation and management of shark resources in Bangladesh.

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A fluorescence immunoassay for human IgG (Ag) was developed using a pH-sensitive polymer prepared by thermal initiation or redox initiation polymerization as a carrier. In the competitive immunoassay, appropriate quantity of Ag was immobilized on the polymer and the standard Ag (or sample) solution, and a constant amount of fluorescein isothiocyanate labeled goat anti-human IgG antibody (Ab-FITC) was added. Immobilized Ag and the standard (or sample) Ag competed for binding to the Ab-FITC in 37 C in homogeneous format. After changing the pH to separate the polymer-immune complex precipitate, it was re-dissolved and determined by fluorescence method. The results showed that the immobilization efficiency, immunological reaction activities of immobilized Au and phase transition pH range were improved as Ag was immobilized by thermal initiation instead of redox initiation polymerization. Under optimum conditions, the calibration graphs for the Ag in both methods, thermal initiation and redox initiation, were linear over the concentration range of 0.0-1000 ng mL(-1), with detection limits 8 (thermal initiation) and 12 ng mL(1) (redox initiation), respectively. Moreover, some pH-sensitive polymer prepared only in organic solvent or under high temperature could also be used as an immunoreaction carrier by thermal initiation polymerization. Thermal initiation polymerization was a better immobilization mode. (C) 2004 Elsevier B.V. All rights reserved.

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A novel sol-gel method is applied for the preparation of solid-phase microextraction (SPME) fibers. Scanning electron microscopy experiments suggested a porous structure for the poly(dimethylsiloxane) (PDMS) coating. SPME-GC analysis provided evidence that the sol-gel fibers have some advantages, such as high thermal stability, efficient extraction rates, high velocities of mass transfer, and spacious range of application.

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Via the combination of an electrospinning method with a hydrothermal reaction, a large-scale cedar-like hierarchical nanostructured TiO2 film with an anatase/rutile composite phase was fabricated.

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A 1.55 mu m InGaAsP/InGaAsP multiple-quantum-well electro-absorption modulator (EAM) monolithically integrated with a distributed feedback laser (DFB) diode has been realized based on a novel butt-joint scheme by ultra-low metal-organic vapour phase epitaxy for the first time. The threshold current of 25 mA and an extinction ratio of more than 30 dB are obtained by using the novel structure. The beam divergence angles at the horizontal and vertical directions are as small as 19.3 degrees x 13 degrees, respectively, without a spot-size converter by undercutting the InGaAsP active region. The capacitance of the ridge waveguide device with a deep mesa buried by polyimide was reduced down to 0.30 pF.

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Samples have been prepared at different temperatures by loading It molecules into the cages of zeolite 5A, and the measurements of the absorption spectra have been carried out for the prepared samples. It is shown that 12 molecular clusters are formed in the cages of zeolite 5A, and it is also found that molecular clusters which are bonded with intermolecular forces have an important feature, namely, the intermolecular distance in molecular clusters can be changed on different preparing conditions and the blue shift of absorption edges can not be as the criterion of forming molecular clusters.

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我国江西龙南稀土矿是目前世界上储量最大的富钇稀土矿、研制具有多种用途的钇(Y)-铝(Al)或富钇混合稀土(Ymm)-铝中间合金,对于开拓我国龙南稀土矿的应用领域扩大稀土合金出口具有重要意义。基于这一背景并针对目前氟化物体系制取Ymm-Al合金时存在着电解温度高,腐蚀现象严重,电效偏低等缺点,本文系统开展了在氯化物熔盐体系中电解制取Ymm-Al合金的研究工作。本工作由三部分组成:在第一部分工作中,开展了熔盐电解所需要基本原料-无水稀土氯化物制取的工艺研究。利用化学分析和结构分析手段,弄清了干法氯化过程中YmmCl_3水解的机理,提出了减弱水解的措施,即YmmCl_3先在850-900 ℃灼烧1.5 + 0.2hr,脱掉吸附水并将碱式碳酸盐转化为氧化物,增加稀土氧化物的比表面。通过条件试验得到最佳工艺条件为:采用NH_4 Cl:Ymm_2 O_3 = 14:1(摩尔比)的配料比,每次投入氯化装置的原料量为0.26 - 0.36 kg, 在400-450 ℃氯化反应激烈开始后迅速降温至400 ℃以下,待物料粘结现象消失后,再行升温氯化。出料及后期控制温在475 ± 25 ℃。经过3.8 ± 0.2hr氯化,可制得水不溶物小于1%并符合熔盐电解要求的YmmCl_3原料。此新工艺与原有干法工艺相比,流程短,装置简单,不需密闭抽真空,成本低,适于制取任何量的优质熔盐电解所需氯化稀土原料。在第二部分工作中,利用上述YmmCl_3原料,以液态铝为阴极,在氯化物体系中进行熔盐电解,通过试验得出在小型试验规模制取Ymm-Al合金的最隹工艺条件为:电解质组成(重量比)40%YmmCl_3-1%NaF-59%等摩尔的NaCl-KCl;电解温度为790 ± 5 ℃;阴极电流密为0.7 - 0.02A/cm~2;电解电量为333 ± 5库仑/克铝,制得钇铝合金中Ymm含量为10 ± 2%。添加1%的NaF可消除阴极表面生成枝状物,减少合金中夹渣和熔盐中沉渣。在电解工作中,将方差分析应用于试验数据处理,方差分析结果表明,各种试验因素对电效有明显影响,试验数据可靠,试验误差在允许范围以内。在第三部分工作中,利用线性扫描伏安法测定了在最隹电解工艺条件下Y~(3+)和Ymm在液态铝及钼电极上的析出电位。测定结果表明:Y~(3+)和Ymm~(3+)在液态铝阴极上的析出电位比在钼阴极上偏正0.2 ~ 0.8伏,氟离子的加入要比不加氟时析出电位不有同程度的负移,但考虑到氟离了具有消渣作用,加入少量氟比物添加剂对提高电效有利。