掺混肥料的试样制备

根据国标要求取掺混肥料 191919缩分样品 5 0 0 g,经缩分 3次成为 4个 12 5 g样品 ,将 4个 12 5 g样品分别制成通过 0 .5 mm孔径筛并且混合均匀的试样 ,然后作成分分析 ,结果重现性差 ,如总氮含量分析结果分别为 19.6、18.8、19.1、2 0 .0。表明了该种试样制备的方法不适用于某些掺混肥料。由于掺混肥料中各种基础物料含量、形态、粒径、表观密度各不相同 ,为了保证原始样品的各部分能够以相同的概率进入最终样品 ,我们取掺混肥料样品 5 0 0 g,采取 2次重新缩分的分样方式 ,将原样品缩分为 2个 2 5 0 g样品。将上述 2个 2 5 0 g样品分别制成…     

聚丙烯粉料乙烯含量测定影响因素研究

利用外商提供的分析方法和一系列标样样片,建立了无规和抗冲共聚聚丙烯中乙烯含量测定的工作曲线,由于聚丙烯粉料样品结构与性质的不稳定性和不均匀性,决定了实际粉料样品乙烯含量在测试处理上往往不能完全与建立标线处理上的一致。通过选取不同牌号乙丙共聚聚丙烯粉料样品,着重试验分析了热压制样中冷却方式、抗氧剂、样品粒径对粉料乙烯含量测定结果的影响。结果表明,热压制样中冷却方式对粉料乙烯含量的测定结果形成了较为明显的影响;同样粉料样品中是否添加抗氧剂及所加抗氧剂的种类对测定结果也构成了很大程度的影响;另外,粉料样品粒径对乙烯含量的测定结果形成了显著的影响。     

蛋白质含量测定方法的比较

蛋白质与生命的起源、存在和进化都密切相关,蛋白质含量测定涉及到生产和科研的众多领域.目前常用的方法有凯氏定氮法、双缩脲法(Biuret)、紫外吸收法、考马斯亮蓝法(Bradford).本文总结各种方法的特点及适用条件,针对不同的待测样品以及对测定结果准确性的要求不同,我们可以采用不同的方法来测定样品中蛋白质的含量.     

XRF测定钒钛磁铁矿中铁、钒、钛和硅含量

实验采用粉末压片法制样,使用能量色散X射线荧光光谱法(XRF),实现了对钒钛磁铁矿中铁、钒、钛和硅含量的快速测定。通过将测定值与标准值进行比较,得出最优实验条件,包括样品粒径、压力、保压时间等。所得四种元素的检出限在0.24～3.93 mg·L~(-1)之间,相对标准偏差(n=8)在5%以下,且标准样品的测定值与标准值相符,实际样品的检测结果与化学法一致。本方法快速、准确,适用于钒钛磁铁矿中铁、钒、钛和硅含量的测定。     

有机肥料氮、磷、钾的化学分析方法

介绍用化学分析方法测定有机肥料氮、磷、钾的含量,即样品经硫酸-过氧化氢消化后,制备待测溶液,分取待测溶液用NC-2型快速定氮仪测定氮,用磷钼酸喹啉重量法测定磷,用四苯硼酸钾重量法测定钾,不需使用分光光度计和火焰光度计,适宜一般复混肥料厂采用,对含氮、磷、钾分别达0.1%以上的样品均可用本法测定,方法的准确度和精密度能满足生产的要求。     

工业氢中氧、氩和氮含量测定方法技术革新

目前,工业氢气分析项目执行国家标准(GB/T3634.1—2006)。其中氧、氩和氮含量的测定采用的是气相色谱法,配备脱氧柱和切换柱两次进样,测定样品气中氩和氮的含量,用差减法计算出样品。此方法人为地两次手动进样,每次分析样品在六通阀的定量管中由于受温度压力不同给分析结果带来人为误差。因此,利用现有用于微量硫分析的6890N气相色谱仪进行革新改造,一次进样不受前后进样温度和压力的影响,完成全分析。     

提高固相萃取—高效液相色谱法测定水中微囊藻毒素回收率方法研究

通过对前处理过程中关键环节进行单因素不同水平比较,选择出固相萃取样品温度、上样体积、上样速度、浓缩体积、浓缩温度、氮吹流量等因素的最优实验方案,建立了一种简单有效省时及回收率较佳的前处理流程。研究获得各因素优化值分别为固相萃取上样温度40℃,上样体积1000mL,上样速度10mL/min,浓缩温度45℃,氮吹浓缩流量控制在6-13mL之间,采用80%甲醇溶液每次0.5mL分两次洗脱。     

纺织助剂中溶剂含量的测定方法研究

采用气相色谱和顶空进样法相结合对纺织助剂中溶剂的含量进行测定，建立了顶空进样外标法测试纺织助剂中溶剂含量的方法，确定了用水和二乙二醇丁醚作为溶剂检测纺织助剂中溶剂含量的可行性，并对不同待测产品（水相样品和油相样品）中的溶剂含量进行了测定。实验结果表明，该方法可用于纺织助剂中甲醇、乙醇、异丙醇、正丁醇、乙二醇丁醚和二乙二醇丁醚等溶剂含量的测定，水相和油相样品中溶剂含量的测定结果和理论值相差不大，平均相对标准偏差均小于2.0%，平均回收率在97.7%～104.5%之间，该方法的检测下限为0.10%。研究结果认为，该方法操作简单、检测速度快、灵敏度高，适用于纺织助剂中不同溶剂含量的分析测定。     

电极糊挥发分测定影响因素分析

对电极糊挥发分测定过程中的取样、样品制备、样品粒度、样品存留时问、称样量等影响因素进行分析。结果发现,样品的取样和制样能够显著影响挥发分测定结果,电极糊的挥发分随样品的留存时间逐渐降低,称样量对测定结果有一定影响,样品粒度对测定结果的影响较小。通过对试验方法和整个过程检测的精密度测定,结果表明了检测精密度主要影响在于取样和制样环节。     

脉冲加热惰气熔融-热导法测定金刚石微粉中的氧氮含量

目前,金刚石微粉在切削、磨削、钻探等领域的应用日趋广泛,国内外市场需求也有所扩大。文章采用脉冲加热惰气熔融-热导法测定金刚石微粉中的氧氮含量,对分析功率、助熔剂等进行了研究,在称样量为0.02~0.05g,镍助熔剂为0.37g,分析功率为5.5kW的条件下,通过脉冲加热惰气熔融-热导法并同时采用测定金刚石微粉中氧和氮含量的方法,对金刚石微粉样品中氧和氮进行了9次测定,其测定结果的相对标准偏差分别为2.36%和4.08%。结果与脉冲加热惰气熔融-质谱法所得氧和氮的测定值一致。     

Adjustment and Online Determination of Primary Particle Size in Transferred Arc Synthesis of Copper Nanoparticles

Scaling up metal nanoparticle production is a desired goal of much research, the need of the industry due to the growing market of applications increases significantly. However, a scale up of production rate often leads to an increase in particle size and a broadening of size distribution. Particle characterization in terms of size is mostly done after synthesis. In this work, a transferred arc process is optimized to increase the production rate of pure copper nanoparticles economically. The maximum production rate for different particle sizes is determined by TEOM measurements. While the influence of different carrier gases has been investigated before, different mixtures of nitrogen and argon as carrier gas are used to manipulate the primary particle size. Primary particle size determination is performed by a novel analysis method based on parallel online ELPI and SMPS measurement. An equation is found to calculate the mass mobility exponent directly on the basis of the effective density of an agglomerate. Hence, the method is suitable for determining the primary particle sizes directly online.

Copyright 2013 American Association for Aerosol Research     

Effects of particle shape and size on devolatilization of biomass particle

Experimental and theoretical investigations indicate particle shape and size influence biomass particle dynamics, including drying, heating rate, and reaction rate. Experimental samples include disc/flake-like, cylindrical/cylinder-like, and equant (nearly spherical) shapes of wood particles with similar particle masses and volumes but different surface areas. Small samples (320 μm) passed through a laboratory entrained-flow reactor in a nitrogen atmosphere and a maximum reactor wall temperature of 1600 K. Large samples were suspended in the center of a single-particle reactor. Experimental data indicate that equant particles react more slowly than the other shapes, with the difference becoming more significant as particle mass or aspect ratio increases and reaching a factor of two or more for particles with sizes over 10 mm. A one-dimensional, time-dependent particle model simulates the rapid pyrolysis process of particles with different shapes. The model characterizes particles in three basic shapes (sphere, cylinder, and flat plate). With the particle geometric information (particle aspect ratio, volume, and surface area) included, this model simulates the devolatilization process of biomass particles of any shape. Model simulations of the three shapes show satisfactory agreement with the experimental data. Model predictions show that both particle shape and size affect the product yield distribution. Near-spherical particles exhibit lower volatile and higher tar yields relative to aspherical particles with the same mass under similar conditions. Volatile yields decrease with increasing particle size for particles of all shapes. Assuming spherical or isothermal conditions for biomass particles leads to large errors at most biomass particle sizes of practical interest.     

Condensed Combustion Products of Aluminized Propellants. III. Effect of an Inert Gaseous Combustion Environment

The effect of gaseous combustion environment on particle size distribution and chemical compositions of condensed combustion products of a model propellant containing ammonium perchlorate, binder, and 23.4% aluminum was studied. Experiments were conducted at pressures of 0.6, 4.0, and 7.5MPa. Oxide particles with sizes of 1.2–60 m and agglomerates with sizes from 60 m to maximum were investigated. In experiments with nitrogen and helium, the difference in the mean sizes of the sampled agglomerates does not exceed the experimental error. The difference in the amount of unreacted (metallic) aluminum in the agglomerates sampled in nitrogen and helium is also negligible. Replacement of nitrogen by helium affects the size distribution of the oxide particles by increasing the mass fraction of particles with sizes of 1.2–10 m, and this effect is enhanced with pressure.     

澳洲铁矿石粒度分布和铁含量关系的研究与探讨

工作中发现,不同粒径块铁矿的铁含量存在着较大的差异,研究粒度分布与铁含量的关系对手工取样和实验检测有现实的指导和参考意义,同时也能减少贸易纠纷。文章通过选样、筛分、磨样、烘样、溶样等手段对样品进行处理,并按标准ISO9507-1990对样品进行全铁含量检测,考察铁含量随不同粒径块铁矿的变化。结果表明:不同粒径块铁矿的铁含量存在着较大差异,最大偏差达到3.74%,这种差异被认为是块铁矿的结构、组分以及在破碎时不同的破碎方式导致的。     

Monodisperse fine aerosol generation using fluidized bed

Monodisperse, fine aerosols are needed in many applications: filter testing, experiments for testing models, and aerosol instrument calibration, among others. Usually, monodisperse fine aerosols are generated in very low concentrations, or mass flow rates, in the laboratory scale. In this work, we needed to generate aerosols with higher mass flow rate than typically available by the laboratory-scale methods, such as atomizers, nebulizers, ultrasonic generators, vibrating orifice generators, and condensation generators. Therefore, we constructed a fluidized bed aerosol generator to achieve particle mass flow rates in the range of 15-100 g/h. Monodisperse, spherical SiO₂ particles of two sizes with geometrical diameters of 1.0 and 2.6 µm were used in the aerosol generator. The aerosol generator was used at both atmospheric pressure, and at high pressures up to 5 bar (abs).The particle size, mass concentration and the net average particle charge were measured after mixing the aerosol with nitrogen. The particle size distributions with both particle sizes were monodisperse, and no particle agglomerates were entrained from the fluidized bed. The behavior of the fluidized bed generator was found to be markedly different with the two particle sizes in regard to particle concentration, presumably due to different particle charging inside the generator. After determining the net average charge of the particles, an ion source Kr-85 was used to reduce the charge of the particles. This was found to be effective in neutralizing the particles.     

Experimental study on the effects of drying methods on the stabilities of lignite

The drying processes are always applied prior to the transportation or utilization of lignite, and result in notable changes in the stabilities of lignite. In this paper, the study on the effects of nitrogen and MTE drying process on the physico-chemical properties and stabilities of Zhaotong lignite was carried out. The briquettes produced by MTE drying in this study were 150 mm in dimension, and so had a much larger particle size than nitrogendried samples. Nitrogen adsorption, mercury intrusion porosimetry and scanning electron microscopy all suggested that drying was accompanied by the transformation of larger pores into smaller ones. Compared to nitrogen drying, the pore structures could be stabilized by the MTE process. The soluble salts were removed during MTE drying which resulted in the decrease in ash and the concentrations of some of the major metals.The removal of water enhanced the hydrophilicity of nitrogen dried samples, but did not affect the hydrophilicity of MTE dried samples. The moisture holding capacity of MTE dried samples reduced faster than nitrogen dried samples with the decrease of residual moisture content. Themoisture readsorption processes of MTE dried sampleswere strongly inhibited due to themuch larger particle size of sample produced byMTE drying than nitrogen drying. The susceptibility to spontaneous combustion, indicated by cross point temperature and self-heating tests, of nitrogen and MTE dried samples increased with the decrease of residual moisture content. The MTE dried samples are more liable to spontaneous combustion than nitrogen dried samples with the same residual moisture and particle size. However, the larger particle size of the MTE product made it more stable with respect to spontaneous combustion and also moisture readsorption.     

不同粒径胶粉的成分分析及在胎面胶中的应用

通过热重法和红外光谱分析及测定硫含量和粒径分布等方式对用超低温粉碎法制备的不同粒径胶粉的成分进行了分析,并开展了其在商用车轮胎胎面胶中的加工应用研究。结果表明,4种不同胶粉中的挥发分、有机物、炭黑和灰分含量均差别较小,其中有机物质量分数在61%～65%之间,炭黑质量分数在28%～30%之间,含硫质量分数在2%左右,粒径从小到大依次为牌号K 0004、K 0002-R、W 0004和W 0406的胶粉。在商用车胎面胶中添加10份（质量）胶粉,混炼胶的门尼黏度增大,门尼焦烧时间缩短,硫化速率加快。胶粉粒径越小其对硫化胶物理机械性能的影响越小,而硫化胶损耗因子的变化与胶粉粒径的相关性较小。     

直流电弧等离子体制备TiN纳米粉末的研究

采用直流电弧等离子体蒸发－冷凝法制备出了粒径可控的高纯所化钛纳米粉末。探讨了等离子体条件下氮经反应过程和影响ＴｉＮ粉末粒度的关键工艺参数。研究表明，高温氮等离子体条件下存在着大量的高活性基团，它们参与也氮化反应，提高了氮化反应活性。     

Hemolitic Activity and Sorption Ability of Beta Zeolite Nanoparticles

The work is devoted to studying the influence of synthesis conditions on the hydrothermal crystallization of zeolite nanoparticles with a Beta structure and studying their properties. The experimentally optimal conditions for the preparation of Beta zeolite nanoparticles of various sizes are determined by varying the temperature and time parameters of the process. The synthesized samples are characterized by X-ray diffraction analysis, scanning electron microscopy, and low-temperature nitrogen adsorption. The sorption ability of zeolite samples of different sizes with respect to inorganic cations (for example, lead ions) and organic molecules (for example, thiamine hydrochloride), as well as their hemolytic activity in relation to human red blood cells, is studied. It is found that the sorption ability of the samples decreases with increasing particle size. For the first time, the results of the dependence of the hemolytic activity of nanoparticles on their size are obtained. Based on the results obtained, conclusions are drawn about the possibility of using nanozeolites in medicine.