关于用离子选择电极法测定植物中氟化物的探讨

采用离子选择电极法测定植物中的氟化物:植物样品先用0.05mol/L硝酸溶液浸提,然后再用0.1mol/L氢氧化钾溶液继续浸提,用氟离子选择性电极法来测定;该方法具有精密度和回收率都较好的特点。     

离子选择电极法和离子色谱法测定水中氟化物的比对分析

采用离子色谱法(简称IC)和离子选择电极法(简称ISE)对水中氟化物的测定进行了研究和探讨,两种方法线性相关性相当,IC测定水中氟化物的检出限为0.02 mg/L,较ISE(0.05mg/L)略低。本文对两种方法的原理、精密度、准确度做了深入的分析。测定结果表明ISE测定水中氟化物具有选择性好、准确快速、投资小、耗材便宜,检测范围宽(0.05 mg/L~1900 mg/L)的优点,同时对地表水、地下水和工业废水均能检测。而IC仅用于干净的地表水(监测范围为0.06 mg/L~10 mg/L)中氟化物的测定,该方法虽然测定时间长于ISE,但自动化程度及数据处理效率优越于ISE,当需要同时分析Cl-、NO2-、NO3-、SO42-等阴离子时,IC就显示出其强大的优越性,能大大提高工作效率。     

离子选择电极法测定污染源废气中的氟化物

污染源废气中的氟化物分为气氟和尘氟.本文详细介绍了离子选择电极法测定气氟和尘氟的分析方法以及在测试中应注意的问题。     

电极法和离子色谱法测定生活饮用水中氟化物的比较

本文通过实验的方法对电极法和离子色谱法测定生活饮用水中氟化物进行了比较,经过实验分析比较得出结论一两种方法相差不大,都可以采用,并总结了各个方法的优缺点。     

离子选择电极法在水质分析中的应用

本文通过实验比较,离子选择电极法用于水中硝酸盐氮测定,准确度、精密度、抗干扰性高。回收率为97.0%～102.0%。除氯离子、亚硝酸根离子外,不出现其它具有干扰意义水平的离子。     

氟离子选择电极法测定牙膏中的氟

验证了离子选择电极法测定氟化物的特征指标,结果表明:测定下限为0.04 mg/L,标本标准偏差为0.0026,相对标准偏差<2.7%,回收率在97~103%.说明该方法的精密度好,准确度高,符合质量控制要求。     

离子选择电极法电解质分析仪常见问题与解决方法

离子选择电极法电解质分析仪以其测定方法简单,测量结果准确而被广泛应用于各临床实验室。本文对电解质分析仪在计量检定过程中常见的问题进行了浅析和解决。     

水样中氟化物检测方法的应用进展

综述了近10年来对水体中氟化物测定方法的研究进展。离子选择电极法简便且仪器价格低廉。离子色谱法可以同时测定4种阴离子,检测效率高。分光光度法简便、准确,还可以测定污水中的氟含量。     

离子色谱法单独测定清洁水样中的氟化物

离子色谱可以一次进样同时测定四种阴离子。通过实验得出:单独测定氟化物含量时,最佳分析时间间隔设为4分钟,线性范围0.20 mg/L~1.40 mg/L,相对误差1.65%,相对标准偏差0.43%~7.6%,对相对清洁的水样,可实现大量样品氟化物的快速、准确测定。     

离子选择电极法测定氨氮浓度

本文介绍一种新型的测量氨氮浓度的方法——铵离子选择电极分析法。与传统测量氨氮浓度的分光光度法相比,具有测量快速、准确、操作容易及所需试剂少等优点。     

Di-tert-butylazodicarboxylate based PVC membrane sensor for Fe(III) ion measurement in pharmaceutical formulation

Preliminary solution study shows the selectivity of di-tert-butylazodicarboxylate (TBADC) toward Fe(III) ions. Due to this selectivity, it was applied as an ionophore for construction of a Fe(III) sensor. The proposed sensor exhibits a wide linear response range with a Nerstian slope of 19.4 ± 0.4 mV decade^− 1 and detection limit of 4.8 × 10^− 8 mol L^− 1. The sensor response is pH independent in the range of 2.3-3.4 and has a fast response time of < 10 s. It also shows very good selectivity to Fe(III) ion over many mono-,di- and trivalent transition and heavy metal ions. The life time of the electrode was at least 10 weeks. The application of the TBADC-based sensor to analysis of Fe(III) ion in a pharmaceutical formulation, and also to the monitoring of Fe(III) ion in mixtures of two, three and four different ions showed satisfactory results.     

Fabrication of electrically conductive membrane electrode of gelatin-tin (IV) phosphate nanocomposite for the detection of cobalt (II) ions

Gelatin-tin (IV) phosphate nanocomposite (GT/TPNC) ion exchanger was synthesized by mixing gelatin gel into the precipitates of tin (IV) phosphate using sol–gel method. GT/TPNC was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ion exchange capacity of GT/TPNC was reported to be1.44?meq/g. The material was found monofunctional as indicated from pH titration curves. The distribution coefficient of different metal ions such as Zn²⁺ (42.10), Cd²⁺ (37.93), Mg²⁺ (33.33), Cu²⁺ (33.21), Al³⁺ (14.28), Pb²⁺ (6.06), Ni²⁺ (12.50) and Co²⁺ (50.0) was studied using GT/TPNC ion exchanger. The distribution studies confirmed the selectivity of GT/TPNC for Co (II). The photocatalytical degradation of MB was found to be 78% within 5 h of solar illumination using GT/TPNC. Some binary separations such as Co²⁺–Pb²⁺, Cd²⁺–Ni²⁺, Co²⁺–Mg²⁺, Mg²⁺–Zn²⁺, Pb²⁺–Zn²⁺, Cu²⁺–Al³⁺, Al³⁺–Cd²⁺, Ni²⁺–Cu²⁺ were attempted using GT/TPNC ion exchanger. GT/TPNC was explored for the fabrication of ion-sensitive membrane electrode for the determination of Co (II) in the water system. The membrane electrode was found mechanically more stable with quick response time (30?s) and a wide pH working range (4.0–7.0).     

A quality control method for complex product selective assembly processes

Selective assembly is an important step during the manufacturing process for a complex product to meet precision requirements. The high precision requirement of complex product often results in producing a large number of surplus components in selective assembly process current practices. In this paper, we develop a comprehensive model which permits the integration of machining process parameters design, variation analysis and fault diagnosis, process adjustment and control strategy, process capability index calculation and matchable degree calculation. The model can be applied to evaluate and improve product, process and system design at early development stages, or support the improvement of matchable degree for a complex production selective assembly process. In this model, we have introduced a navel concept of general matchable degree for a multiple components selective assembly process. The implementation procedure and functional modules of the proposed model are given in details with an industrial case presented to illustrate the implementation of the proposed method.     

Nano-magnetically modified activated carbon prepared by oak shell for treatment of wastewater containing fluoride ion

In this study, the adsorption of fluoride ion (F^-) from synthetic wastewater was performed using activated carbon/Fe₃O₄ nanocomposite in a batch system. To prepare activated carbon (AC), oak shell was used. Also, several analyses such as BET, SEM, EDX, FTIR, XRD, VSM and DLS analyzes were used to study the structure and morphology of the AC/Fe₃O₄ nanocomposite. BET analysis indicated that the specific surface area of Fe₃O₄ and AC/Fe₃O₄ were 65.44 and 226.78 m²/g, respectively, which shows the surface area of the AC/Fe₃O₄ composite was significantly increased compared to Fe₃O₄. Also, the particle size of the AC/Fe₃O₄ composite was obtained 75 nm by the DLS analysis. The sorption tests indicated that the highest sorption efficiency of fluoride ion using the Fe₃O₄/AC nanocomposite was obtained 97.4%. Moreover, the experimental results were well fitted with the Freundlich model. The maximum monolayer uptake capacity using the AC/Fe₃O₄ was obtained as 454.54 mg/g and showed a remarkable adsorption capacity, whichever achieved for fluoride ion sorption. Also, zero-point charge of pH (pHzpc) was obtained 5. Furthermore, the kinetic data were described by the quasi-second-order model. Besides, the thermodynamic parameters showed that the uptake of fluoride ion with the AC/Fe₃O₄ nanocomposite was spontaneous, practical, and endothermic. The outcomes suggest that AC/Fe₃O₄ nanocomposite can be effectively applied for the F^- ion removal from synthetic wastewater.     

Formation of uniaxially strained SiGe by selective ion implantation technique

Uniaxially strained SiGe layers were fabricated with a newly developed selective-ion-implantation technique. The SiGe layer was grown on the Si substrate, into which laterally selective ion-implantation with stripe pattern was carried out prior to the SiGe growth. A strain-relaxation of the SiGe layer was largely enhanced due to ion-implantation-induced defects selectively in the ion-implanted area while it was hardly enhanced in the neighboring unimplanted area. However, micro-Raman mapping and X-ray diffraction reciprocal space mapping measurements obviously revealed that the relaxed SiGe in the implanted area remarkably influenced a strain state of the neighboring strained SiGe in the unimplanted area, that is, the strain along the stripe line direction was highly relieved due to the stress caused by the neighboring relaxed SiGe while the strain in the direction perpendicular to the line was well maintained. As a result, highly asymmetric strain state, that is, uniaxial strain was realized, where 4 times different relaxation ratios in the two directions were observed. These results indicate that the selective-ion-implantation technique developed in this study has a high potential to realize uniaxially strained Si/Ge channel devices with high mobility.     

饮用水中pH测量结果的不确定度评定

目的:为减少实验误差,提高检测结果精确度,评定饮用水中PH测量结果的不确定度。方法:分析饮用水中PH测量结果的不确定度的来源,通过计算得出该法测定饮用水中PH测量结果的扩展不确定度。结果:不确定度评定结果为PH=7.68±0.03,p=95%。结论:该方法操作简便,可参考用于水中检测参数的不确定度评定。     

Quality control results of the drift tubes for the ATLAS MDT-BIS chambers

ATLAS (A Toroidal LHC ApparatuS) is a general purpose experiment, which will start its operation at the Large Hadron Collider (LHC) at CERN in 2007. The ATLAS detector is designed to study the products of proton–proton collisions at c.m.s. energies of up to 14 TeV. Three Greek Universities have taken the responsibility to construct 112 BIS-MDT (Barrel Inner Small) chambers using 29 000 drift tubes of 170 cm length and 3 cm diameter that have been quality tested before assembly. This work describes the Quality Assurance and Quality Control (QA_QC) procedures for the drift tubes, followed at the High Energy Physics Laboratory of the National Technical University of Athens, while emphasis is given on the obtained results for the above mentioned number of tubes.     

Preparation of floral mesoporous SAPO-34 with the aid of fluoride ion

A novel floral mesoporous SAPO-34 was synthesized via conventional hydrothermal method in the presence of NaF with F/Si = 0.02-0.2. X-ray diffraction (XRD) analysis shows that the crystallinity of SAPO-34 increases with the increasing F/Si ratio and reaches to the best at F/Si = 0.1. Further increasing of F/Si ratio leads to the decrease of the crystallinity and the ultimate phase transformation to SAPO-5. Scanning electron microscopy (SEM) analysis shows that the addition of NaF leads to the formation of floral SAPO-34 while the addition of other salts including NH₄F, NH₄Cl and NaCl leads to the formation of traditional cubic SAPO-34. N₂ sorption isotherm and NH₃ temperature programmed desorption (NH₃-TPD) analyses indicate that floral SAPO-34 has the largest pore volume but lowest strong acidity compared with other samples with traditional cubic morphology. When applied to methanol to olefin (MTO) reactions, floral SAPO-34 shows the comparable yields of propylene and butylenes to other samples but lowest overall olefin yield, which is attributed to the synergistic effect of the largest pore volume and lowest strong acidity.