流动注射法和纳氏试剂法测定地表水中氨氮的比较研究

纳氏试剂法是国家的标准方法,流动注射法是近年来发展起来的一种分析方法,已在国外得到广泛运用,但国内的实际应用还较少。本文对分光光度法和流动注射分析法测定水中的氨氮进行了比对实验,结论如下：纳氏试剂法检测范围0.02~2.0mg/L,检出限0.02mg/L;流动注射法测定水样中的氨氮,检测范围0.01~10.0mg/L,检出限0.001mg/L,分析速率50个样品/h;流动注射法法操作简便、线性好,灵敏度、精密度、准确度都能符合分析工作要求,分析速度快、试剂和样品消耗少,是一种灵敏度高、选择性好、环境友好的测定方法,该方法是未来发展的趋势。     

NR光度法测定Fenton试剂所生成的羟基自由基

要提高Fenton试剂在废水处理中的效率,关键就是要提高羟自由基的生成率和利用率。本文提出了检测Fenton试剂反应产生羟自由基的新方法,羟自由基氧化中性红使其褪色,用分光光度法测定其△A值的变化,可间接测定羟自由基的产生量。并考查了FeSO4投加量、H2O2投加量、酸度、反应时间等影响羟自由基生成量的主要因素,为Fenton试剂在废水处理中的应用提供了参数依据。另外,该法稳定性好,操作简单,测定快速。     

三井物产公司销售高纯试剂用大型容器

三井物产公司开发了集成电路生产用的高纯试剂专用大型塑料容器,并以商品牌号“PAC15”正式销售。该容器是用可熔性聚四氟乙烯(PFA)吹塑成型的,容量为15 1。外面还有用泡沫聚氨酯填充的聚丙烯与高密度聚乙烯共混物制成的保护层。与试剂接触的器壁采用耐药性好,且不粘附的PFA,易于清洗。此外,试剂系由氮气压出,因此不易混入不纯     

水中总磷快速测定法研究

本文报道利用化学需氧量（COD）消解加热器消解、快速测定水中总磷的方法。线性区间内该方法具有线性关系好,精密度和准确度较高,分析速率快、试剂耗量低等优点,可应用于大批量水样分析。     

纳氏试剂比色法测定高浓度有机废水中氨氮预处理方法的研究

目的:建立一种测定高浓度工业有机废水中氨氮含量的纳氏试剂比色法。方法:利用干扰纳氏试剂比色反应的有机物和三氯甲烷互溶,用三氯甲烷萃取弃去消除干扰。结果:工作曲线在0.10-2.0mg/L氨氮浓度范围内线性关系良好,线性相关系数为0.9993,平均加标回收率为93.6%--105.8%,相对标准偏差小于2.58%,方法的检出限为0.029mg/L。结论:该方法操作简便、去干扰效果好、灵敏、结果可靠。     

用原子吸收法测定活化液中含钯量

(一)引言 在研制电池性能的过程中,人们已经发现活化液中钯离子浓度的量对电池技术性能的变化起着十分明显的作用,因而研究一种快速、准确、精确度好、灵敏度高的测定钯离子含量的分析方法,是非常必要的。 据国内外文献报道,目前测定钯离子含量分析方法大多采用有机试剂来定量测定钯,有机试剂中的肟类试剂居多,如丁二醇肟,β—糖醛肟,α—安息肟,水杨醛肟等等。但这些方法操作不简便,灵敏度也嫌不足。也有用极谱法、X荧光法测定钯离子含量,由于仪器设备等问题,测定效果也不够理想。至于     

半导体光热转换纳米材料的研究进展

癌症已成为严重威胁人们健康的头号杀手,传统的癌症治疗技术存在很多的局限和不足,所以亟需开发一种新型的治疗技术。目前,近红外光驱动的光热消融治疗已经被认为是一种有效的癌症治疗技术,该技术的发展关键是研发高效且生物相容性好的光热转换试剂。半导体光热转换试剂具有价格低廉、光热转换效率高等优点,引起了广泛关注。总结了近年来半导体光热转换试剂的研究进展,主要包括铜基(CuS、Cu_9S_5和CuSe等)和钨基(W_(18)O_(49)、Cs_xWO_3和WS_2等)半导体。另外,还介绍了半导体多功能光热试剂(如G-CuS-DOX和FeS_2-350等)在化疗/热疗或者成像/治疗一体化方面的进展。最后,指出了目前存在的问题和发展方向。     

浅谈高锰酸盐指数测定影响的若干因素

为了准确测定高锰酸盐指数,文中从试剂的配制、蒸馏水水质、空白值、滴定速度、水浴的温度、加热的时间、样品酸度、滴定终点的判断等诸多因素,会影响测定结果,实验操作中,应控制好上述因素的关键点,以提高测试的准确性。     

荧光分析法监测水中矿物油污染的研究

本研究了己烷萃取后荧光分析系统。该系统包括高灵敏度、操作简便的智能化仪器和无二次污染的试剂。标准油溶液代表性好,稳定性好。该系统可解决各具体单位和大面积网络的水中矿物油污染的监测问题。目前,已为某汽车制造厂提供了水中矿物油污染的监测方法,显示出良好的发展前景。     

科研用高纯试剂中不挥发性有机杂质分析

对国内外典型科研用HPLC级的甲醇、异丙醇和乙腈中的有机杂质进行高效液相色谱-飞行时间质谱非目标分析。实验结果表明:对每一种HPLC级高纯有机试剂而言,使用原液样品进行非目标分析时,国产试剂中有机杂质含量与进口试剂中有机杂质无显著差异;但使用原液样品的浓缩液进行非目标分析时,国产高纯试剂中的有机杂质种类远远多于国外高纯试剂中的有机杂质。这有助于了解国产HPLC级试剂与进口试剂质量差异,对提高国产HPLC试剂质量具有参考价值。     

Study of cut point density and process performance of Floatex density separator in fine coal cleaning

Advanced gravity separation of a high-ash (36%) semi-coking coal in a Floatex density separator (FDS) is investigated. The influence of the operating variables on the separation features has been identified. It is established that a higher bed pressure and a higher teeter water flow rate enhance the mass yield of the clean coal albeit with a poorer grade. A higher bed pressure reduces the bed voidage leading to a higher cut point density. Although bed voidage is reduced due to higher teeter water rate, the hydraulic transport increases significantly. A higher pulp density and a higher feed rate introduce severe hindered settling conditions leading to an increase in the cut point density. This results in a poorer product grade with a higher yield. The optimum condition for 23% product ash in a single-stage operation is identified. The yield at the optimum condition is found to be 64.3% which is close to the theoretical maximum for this coal. The dependence of the cut point density as well as Ecart probable (Ep) value on the operating variables is quantified. A specific gravity of separation of below 1.8 and an Ep value of around 0.15 is achievable under controlled operation of the FDS.     

R507A与R404A循环特性的理论与试验研究

在理论和试验上对R507A与R404A两种制冷剂的循环特性进行对比分析.在冷凝温度40.5℃,吸气温度18.3℃,过冷度0℃,压缩机等熵效率0.8的条件下,理论分析表明：R507A的制冷量较R404A高6％左右,COP高2％左右;相同条件下的性能测试结果表明：R507A的制冷量较R404A高2％～4％,COP高1％～2％,排气温度高0～4℃.     

Significance of temperature increase in processing by high-pressure torsion

Experiments and finite element simulations were conducted to measure the temperature increase in processing disc samples by high-pressure torsion. Aluminum, copper, iron and molybdenum were selected as model materials. The temperature increases at the early stages of straining but saturates to steady-state levels at large strains. The increase of temperature is proportional to the hardness and rotation speed and is higher at higher imposed pressures and is somewhat higher at larger distances from the disc center.     

Effect of carbonization temperature on the basic properties of woodceramics impregnated with liquefied wood

In this paper, a new woodceramics impregnated with liquefied wood is developed and the effect of carbonization temperature on the dimension shrinkage, weight loss, density, compressive strength, and volume electrical resistivity is investigated. The results show that, the higher the carbonization temperature is, the higher the dimension shrinkage is, the higher the compressive strength is, and the lower the electrical resistivity is.     

Al2O3f/ZA27复合材料摩擦磨损性能的研究

在ZA27合金中添加不同体积分数的Al2O3短纤维，对其摩擦磨损性能进行了研究。结果表明，Al2O3／ZA27材料的摩擦系数大于ZA27合金，并且纤维体积分数越大，则平均摩擦系数越大。Al2O3f／ZA27材料的耐磨性明显优于ZA27合金，并且与纤维取向有关。     

TA15钛合金两类组织对疲劳性能和断裂韧度的影响

研究了TA15钛合金片状和双态两种典型组织对疲劳性能和断裂韧度的影响,结果表明:在S-N曲线的高应力区,双态组织的疲劳强度高于片状组织;在低应力区,情况则相反,且片状组织的疲劳极限(656MPa)高于双态组织(565MPa).片状组织的疲劳裂纹扩展速率低于双态组织,且断裂韧度K1C高于双态组织,即片状组织的损伤容限性能优于双态组织.     

Analysis of linear resisted projectile motion using the Lambert W function

We solve the linear resisted projectile motion problem using the Lambert W function. In the problem, the launching point is higher than the landing point. The explicit solutions for the range and optimal angle of elevation are expressed in terms of the Lambert W function. The two conclusions can be made for the same projectile: (i) The higher the launching point, the larger the range is. (ii) The higher the launching point, the smaller the optimal angle is.     

Environmental fatigue crack growth in titanium aluminides and hydrogen evolution behaviour

The influence of environment on fatigue crack growth behaviour was investigated both in nearly lamellar and in duplex titanium aluminides, and the hydrogen evolution kinetics was analysed by thermal desorption spectroscopy. The tensile strength of the duplex material decreases in the order of the extent of the water molecule content in the environment: the strength in vacuum is the highest, and decreases in the order of laboratory air and finally in water. In the case of the lamellar material, the fatigue crack growth rate in dry air is higher in the R–C crack plane orientation than that in the L–C crack plane orientation. The crack growth rate becomes higher when the crack grows as the lamellae tear. However, in the case of the duplex material, the crack growth rate in the R–C crack plane orientation is smaller in the low Δ K (Δ K _eff ) region. When cathodic charging is applied, the fatigue crack growth rate becomes higher than in dry air, particularly in the higher stress intensity factor range. The hydrogen evolution rate is increased by cathodic charging, with lower temperature peaks and higher ones. The peaks at lower temperatures are correlated with the decomposition of hydrides and de-training of hydrogen from microstructural imperfections such as microvoids. As-received materials also show an evolution peak at a higher temperature, and the evolution rate is almost independent of cathodic charging. In addition, the evolution rate at a high temperature (above 800 °C) is increased by cathodic charging. The hydrogen is considered to have an important role on fatigue crack growth acceleration.     

Field‐consistent higher‐order free‐interface component mode synthesis

A new free‐interface component mode synthesizing technique based on the notion of higher‐order field consistency is proposed. The present technique employs higher‐order residual attachment modes in addition to kept normal modes while consistency in matching field variables at the substructure interface is maintained. The present field‐consistency approach does not increase the size of the synthesized system even if higher‐order residual attachment modes are included. Higher‐order analyses greatly improves solution accuracy while the final system size always remains the same as the size of the kept normal modes regardless of the order of residual attachment modes. A general procedure of deriving higher‐order residual attachment modes is first described and then a new field‐consistent higher‐order synthesis technique is presented. Copyright © 2001 John Wiley & Sons, Ltd.     

pH响应性乙烯-乙烯醇共聚物分离膜的纳滤特性

具有纳滤特性的pH响应性膜在小分子分离体系中具有广泛应用前景。文中以铸膜液浓度为25%的乙烯-乙烯醇共聚物(EVAL)超滤膜为基膜,接枝具有pH响应性的功能单体甲基丙烯酸二甲氨基乙酯,制备pH响应性EVAL膜,通过考察膜对标准物聚乙二醇(PEG)与无机盐的截留性能,研究其纳滤特性。结果表明,当pH小于pKa时,pH响应性EVAL膜对聚乙二醇(PEG)与无机盐的截留效果均明显高于未接枝膜,接枝率6%的接枝膜对PEG 800、PEG 1000及PEG 2000的截留率均达到90%以上,对二价阳离子的截留率达到80%以上,无机盐的截留顺序为:CaCl_2MgCl_2MgSO_4NaClNa2SO_4。当pH大于pKa时,PEG及无机盐截留率明显下降,膜对PEG 1000的截留率由95.6%降至62.9%,对MgCl_2截留率降至30.6%,截留率及膜水通量变化存在显著的pH响应性。