Preparation technology of ultra-fine powders of Auricularia auricular

Conventional mechanical method and mechanical method combined with vacuum freeze-drying technology were used to make the ultra-fine powders of edible fungus (Auricularia auricular). The content of basic nutrients, amino acid, micro structure and their properties of raw edible fungus and the edible fungus powders obtained with the two methods were analyzed and compared. The granularity size and micro-structure of the pulverized samples were analyzed by SEM and TEM technology. The average granularity size of the edible fungus powder obtained with mechanical method was 1–5 μm, while that obtained with mechanical method combined with vacuum freeze-drying process was 0.5–1 μm. The ultra-fine powders of edible fungus obtained with the two methods had better water recovery capability and quality, and their preserving time was longer than that of raw edible fungus. All the properties of the ultra-fine powders of edible fungus obtained with the vacuum freeze-drying technology were evidently superior to that of the conventional mechanical method. Keywords Auricularia auricula - Edible fungus - Ultra-fine powders - Vacuum freeze-drying CLC number TS205 Document code B Biography: YANG Chun-yu (1975), female, Ph. D. in Engineering Technology Center of Forestry and Wood Workine, Machinery, Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Zhu Hong

Optimal Conditions for Preparing Ultra-Fine CeO_2 Powders in A Submerged Circulative Impinging Stream Reactor

Cerium carbonate powders were produced in a submerged circulation impinging stream reactor （SCISR） from Ce（NO3）3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide （CeO2） powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce（NO3）3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor （STR）.

DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYPROPYLENE FILLED WITH ULTRA-FINE POWDERED RUBBER PARTICLES

Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.

An improved sodium silicate binder modified by ultra-fine powder materials

This paper presents a new method of modifying sodium silicate binder with ultra-fine powders. The sodium silicate binder modified by ultra-fine powder A and the organic B can reduce the addition amount of the binder. The results indicate that the 24 h strength has increased by 39.9% at room temperature and the residual strength has decreased by 30.7% at 800℃, compared to the conventional sodium silicate. An available material to improve the moisture resistance was also found by adding about 2% more inorganic C, and it can increase the moist strength by 20%. In the end, the microanalyses are given to explain the modifying machanism, i. e., the ultra-fine powder A can refine the sodium silicate binder to avoid holes in the binder bond, which can increase the 24 h strength at room temperture, and can lead to more cracks in the bond after the molding sand is heated to 800℃. This is because of the stress caused by the new eutectic complex of modified sodium silicate binder.

Hydrogen Reduction:A Novel Method of Synthesizing Ultra-fine Chromic Oxide Powder

The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide（NaOH）,were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction（XRD） and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.

Strengthening of HT250 by modified ultra-fine ceramic powders

In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, and the effects of the modified ultra-fine ceramic powders on microstructure, mechanical properties and wear resistance were studied. Metallographic examination, tensile test, scanning electron microscopy, and three-dimensional surface topography were applied to analyze and compare the samples containing modified powder with the original samples. The results showed that the most obvious modification effect among the powders was seen in the sample containing powder A, with the graphite and eutectic cells being refined, the tensile strength being increased by 36.9%, and the wear resistance being improved by 45.5% and 47.2% under loads of 150 N and 300 N, respectively. The improvements of mechanical properties and wear resistance in the HT250 cast iron with the modified ultra-fine ceramic powders were attributed to the synergistic effect of the grain refinement with the powder acting as a hard particle phase and the lubrication by the graphite.

Preparation of Ultra-fine Salbutamol Sulfate Particles by Reactive Precipitation and Characterization of Dry Powder Inhalant

The preparation of ultra-fine particles of salbutamol sulphate （SS） was accomplished with a reactive precipitation pathway, in which salbutamol and sulphuric acid were Used as reactants with the solvents of ethanol.The effects of sulphuric acid concentration, reaction temperature, stirring rate, and reaction time onthesize of the particle were investigated. A binary mixture composed of lactose and SS was prepared to evaluate SS. The results showed that ultra-fine SS particles with controlled diameters ranging between 3 μm and 0.8 μm and with a narrow distribution could be achieved. The morphology consisting of clubbed particles wassuccess.fully obtained. The purity of the particles reached above 98% with-UV detection. The dose- of dry powder inhalation was obtained by blending the particles with recrystallized lactose, which acted as a carrier. The deposition quantity of the drug in breathing tract was estimated using a twin imPinger apparatus. Compared with the Shapuer powder （purchased in the market）, the results showed that SS_particles had more quantifies.subsided in simulative lung.. _

Preparation of ultrafine silver powders with controllable size and morphology

The ultrafine silver powders were prepared by liquid reduction method using Arabic gum as dispersant.The effects of different dispersants,pH values,and temperature on the morphology and particle size of silver powders were investigated.It is found that Arabic gum can better adsorb on silver particles via chemical adsorption,and it shows the best dispersive effect among all the selected dispersants.The particle size of silver powders can be finely tuned from 0.34 to 4.09μm by adjusting pH values,while the morphology of silver powders can be tuned by changing the temperature.The silver powders with high tap density higher than 4.0 g/cm3 were successfully prepared in a wide temperature range of 21.8-70°C.Especially,the tap density is higher than 5.0 g/cm3 when the temperature is optimized to be 50°C.The facile process and high silver concentration of this method make it a promising way to prepare high quality silver powders for electronic paste.

Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O_2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.

Fabrication and Characterization of Nano Silver Powder Prepared by Spray Pyrolysis

Silver powder was fabricated by spray pyrolysis, using 2%-20% AgNO3 solution, 336-500 mL/h flux of AgNO3 solution, 0.28-0.32 MPa flux of carrier gas and in the 620-820 ℃ temperature range. The effects of furnace set temperature, concentration of AgNO3 aqueous solution, flux of AgNO3 aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated. The experimental results showed that with the high concentration of AgNO3 aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO3 aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO3 solutions, 336 mL/h flux of AgNO3 aqueous solution, 0.32 MPa flux of carrier gas at 720 ℃ furnace set temperature.

PREPARATION OF SILVER POWDER FOR CONDUCTIVE PASTE

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Effect of Water Chestnut Powder on Gel Properties of Silver Carp Surimi

[Objectives]The effects of water chestnut powder on the gel properties and quality of silver carp surimi were investigated.[Methods]The surimi gel was prepared by adding 0%,1%,2%,3%,4%and 5%of water chestnut powder to the surimi of silver carp.The gel properties,water-holding capacity,cooking loss,whiteness value,puncture and texture profile analysis(TPA)indexes of surimi products were determined to assess the effects of adding different amounts of water chestnut powder on surimi gel.[Results]The results showed that the gel strength,breaking force and depression distance of surimi products increased first and then decreased with the increase of the addition of water chestnut powder.Compared with the control group,the hardness and chewiness of surimi gel in TPA could be significantly improved by adding water chestnut powder.When the addition of water chestnut powder was 2%,the maximum water-holding capacity was 83.68%;the cooking loss rate was the lowest;and the whiteness value was the highest.Adding 2%of water chestnut powder could significantly improve the gel properties of silver carp surimi and obtain a good gel product.[Conclusions]This study provides a scientific basis for the effective utilization of water chestnut resources and the development of new fish surimi products.

Preparation of titanium dioxide/silver sulfate powder and its antibacterial activity

Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2SO4. The granularity of the particles increases from 10.7nm to 28.7nm with the temperature of heat-treatment increasing from 300℃ to 800℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents （MiCs）. When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0×10 -41.5×10 -4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500℃. But when the temperature is beyond 600℃ the MiCs increase quickly, which shows the inferior antibacterial performance.

Silver removal from molten lead through zinc powder injection

A silver removal process was carried out on a Pb-Ag alloy through zinc powder injection of three different sizes （3.55, 44.4 and 734.8μm） with a top submerged lance using nitrogen as carrying gas. The higher silver removal was obtained for the zinc powder size of 44.4μm, while the lowest silver removal efficiency was attained for the smaller particle size. The AgZn phase was detected in the slag for the 44.4 and 734.8μm particle sizes by XRD, which was in agreement with SEM-EDS analysis. Experimental behavior was explained according to the melting and residence time of the injected particles.

Study on Properties of Silver Powder for Maki-e

Maki-e is a traditional Japanese decorative technique that uses the natural lacquer Urushi and metal powders. In 2014, there exist only two companies that manufacture silver powder for the purpose of Maki-e, and this study focuses on comparing the powders manufactured by them. Gloss and color of each silver powder were measured after Maki-e decoration was finished, and EDS (energy-dispersive X-ray spectroscopy) was used to determine the differences in their chemical composition. In addition, to verify the effect of polishing, residual gloss after sulfuration and polishing was measured. The study revealed that the shapes of the silver powders (Maru-fun, No. 1) manufactured by the two companies are different and it affects the occupancy rate of Urushi and powder, which in turn affects their gloss and color. Wakou silver has a very strong resistance to sulfuration;however, owing to its Pd content, its chroma is much lower than that of other powders. It was shown that sulfuration on powder surface can be removed by polishing irrespective of the shape and chemical composition ratio of the particles.

Effects of Supplemental Amount of Tuanfeng Lotus Seed Powder on Quality of Silver Carp Surimi Products

[Objectives]This study was conducted to improve the gel properties of freshwater surimi and its products. [Methods] Tuanfeng lotus seed powder was added to frozen silver carp, and the relationship between the addiamount of Tuanfeng lotus seed powder(1%, 2%, 3%, 4% and 5%) and the quality of surimi products was studied, so as to improve the quality of surimi products. [Results] The water holding capacity(86.71%±0.36%), hardness(3 566.64±51.15) g, chewiness(2 697.16±15.81) g and gel strength(692.54±23.19) of surimi products increased to the maximums when the addition amount of lotus seed powder was 3%. Meanwhile, the cooking loss rate was reduced to the minimum(13.00%±0.17%), and the sensory quality was the best, although the whiteness of surimi products decreased slightly with the increase of Tuanfeng lotus seed powder. Therefore, the quality of silver carp surimi products could be improved obviously when the dosage of Tuanfeng lotus seed powder was 3%. [Conclusions] This study provides more new ideas for improving the quality of silver carp surimi products, and simultaneously makes the development of lotus seed food more diversified.

枸杞粉对白鲢鱼糜凝胶品质的影响

该研究以冷冻白鲢鱼糜为实验原料,向其中添加枸杞粉(wolfberry powder,WP),分析不同添加量[0.25%、0.5%、0.75%、1%、1.5%(质量分数)]的WP对白鲢鱼糜凝胶持水性、蒸煮损失率、白度值、水分分布、凝胶特性、微观结构、感官评价及气味特征的影响。结果表明,随着WP含量的增加,鱼糜凝胶的持水性、硬度、咀嚼性和凝胶强度都表现出先增大后减小的趋势,当WP的添加量为0.5%时达到最大,分别为78.55%、(2716.77±75.76)g、(2185.15±32.46)g和1087 g·cm;而蒸煮损失率则表现出先减小后增大的趋势,在0.5%的添加量时,蒸煮损失率最小,为7.49%。在鱼糜中加入WP后,可以减少鱼糜凝胶中自由水的比例,增加不易流动水的比例,使鱼糜凝胶保留更多水分,且当WP在最适添加量0.5%时,鱼糜凝胶中只检测到结合水和不易流动水,未检测到自由水。适量WP的添加会增强鱼糜凝胶的网络结构,使其变得更加致密均匀。WP的添加会减小鱼糜凝胶的白度值和色泽评分,但在最适添加量0.5%时,其颜色总体可接受。此外,感官评价和电子鼻分析结果表明,当WP在最适添加量0.5%时,可以显著改善鱼糜凝胶的风味品质。研究结果可为生产高品质的鱼糜产品提供理论依据。

银粉对硅异质结太阳电池用低温银浆的影响综述

银浆是硅异质结太阳电池的重要材料,更低的体积电阻率和接触电阻、良好的附着力、优良的细线印刷性能及组件栅线抗腐蚀老化是其不断改进的方向。作为导电相,银粉的性能和含量对银浆有着至关重要的影响。该文基于低温固化银浆导电机理以及SHJ电池对银浆性能的追求,综述了银粉的振实密度、形貌、粒径、表面处理剂及其与有机物的适配。进一步探讨了纳米银粉和银包铜粉在SHJ太阳电池用低温银浆中的应用。

非水溶液体系中晶种法制备球形银纳米颗粒

以丙三醇作溶剂,硝酸银为原料,聚乙烯吡咯烷酮(PVP)为分散剂,硼氢化钠为还原剂制备了银纳米晶种;以此银纳米粒子作为初级晶种,以丙三醇作溶剂和还原剂,通过升温提高丙三醇的还原性制备银纳米颗粒。研究分散剂种类、生长液银浓度、晶种加入量对银粉的影响,采用X射线粉末衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)对制备产物的结构、物相、形貌进行表征。结果表明,通过改变条件可以制备出分散性良好、粒径均匀的70nm左右的球形银粉。

高功率半导体用纳米银焊膏的研究现状

第3代半导体作为核心部件,使得更紧凑、高频率、高功率的电子器件在射频和微波电子、能源转换与储存、雷达和通信等领域展现出广泛的应用潜力。然而,高性能电子器件对其封装材料的导电性、导热性以及连接处的机械性能提出了更为严格的要求。纳米银焊膏因其卓越的低温烧结性能和在高温环境下的出色表现引起了广泛关注。然而,国内银粉和银焊膏产品的质量相对较低,且研发过程缺乏理论指导,必须依赖进口材料。基于高功率半导体用纳米银焊膏,综述了通过液相化学还原法合成纳米银粉的研究进展,以及纳米银焊膏的烧结机理、影响其性能的因素和控制方法,有望为国内纳米银焊膏的研发和生产提供有益的指导和支持。