Fabrication of ultrathin films with large third-order nonlinear optical properties.

An ultrathin composite film containing anionic Ag-His complexes (His: L-Histidine) and oppositely charged BH-PPV was fabricated by means of the electrostatic layer-by-layer self-assembly technique. UV/Vis spectra showed a continuous deposition process of Ag-His complexes and BH-PPV. The film structure was characterized by using small-angle X-ray diffraction, AFM, and SEM. The nonlinear optical properties of the ultrathin film were studied by using the Z-scan technique with a laser duration of 8 ns at a wavelength of 532 nm. The film sample exhibited a strong nonlinear saturated absorption, with an alpha2 value of -3.9 x 10(-5) mW(-1) and a self-defocusing effect with an n2 value of -4.78 x 10 (-12) m2W(-1).     

Characterization of the Nanoscale Microstructure of an Immersion Silver on Sputtered Copper

1 INTRODUCTION Silver and its compounds have received much attention due to their current and potential applica- tions in many areas[1, 2]. As a metal with the highest electrical and thermal conductivities, silver was one of the most important noble metals used in electrical industries in the last century. Several decades ago, however, the development of silver application in electronic area seemed not so quick. The fear for some undesirable phenomena involving silver, like “electrochemi…     

Novel fiber-optic biosensor based on immobilized glutathione S-transferase and sol–gel entrapped bromcresol green for the determination of atrazine

The aim of this work was to investigate, for the first time, the potential of the enzyme glutathione S-transferase I (isoenzyme GST-I) for uses in analytical chemistry. A novel fiber-optic biosensor for the detection and determination of the triazine herbicide atrazine was developed based on maize GST-I expressed in E. coli. The sensing bioactive material was a three-layer mini-sandwich. The enzyme was immobilized on the outer layer that consisted of a hydrophilic polyvinylidenefluoride membrane. This membrane was supported on an inner glass disk by means of an intermediate binder sol–gel layer that incorporated bromcresol green (BCG). The biosensor operated in a static mode at 25 °C and the rate of the enzymatic reaction, using atrazine as a substrate, served as an analytical signal. A calibration curve was obtained for atrazine, with analytically useful concentration range 2.52–125 μM. The sensor detection limit was 0.84 μM. The reproducibility of atrazine sensing was in the order of ±3–5%. The method was successfully applied to the determination of this herbicide in real water samples, without sample preparation steps. Atrazine recovery ranged between 85 and 110%. No interference from other pesticides, such as alachlor and carbaryl was observed in the absence of atrazine. The immobilized enzyme retained about 75% of its original activity after 1 month use. Simply unscrewing the terminal holding ring of the probe and placing a new bioactive sandwich could easily replace a deteriorated mini-sandwich.     

Re-Evaluation of the Activity Coefficients of Aqueous Hydrochloric Acid Solutions up to a Molality of 2.0 Using Two-Parameter Hückel and Pitzer Equations. Part I. Results at 25°C

Simple two-parameter Hückel and Pitzer equations were used for the calculation of the activity coefficients of aqueous hydrochloric acid at 25°C up to a molality of 2.0 mol-kg^–1. The data obtained by Harned and Ehlers^(12,13) from galvanic cells without liquid junction were used in the analysis and the parameters obtained were compared to those obtained from all reliable data presented in the literature for HCl at this temperature. A good agreement between the parameters was always observed. The activity coefficients obtained by the new equations were compared to those suggested by Robinson and Stokes,⁽⁸⁾ Hamer and Wu,⁽¹⁾ and Pitzer and Mayorga,⁽⁹⁾ and good agreement was also found. The data from the most important literature data sets for HCl were also predicted using the new activity coefficient equations, and the magnitude of the resulting errors was close to the precision of the measurements, the errors forming an almost random pattern for all data sets.     

在PVA存在下Os-SnCl_2-亮绿离子缔合体系的研究高纯镍中微量Os的测定

本文研究了Os-SnCl_2-PVA-亮绿离子缔合体系的显色反应,摩尔吸光系数ε_(434)为5.6×10~6L·mol~(-1)·cm~(-1),锇含量在0.1～0.7μg/25mL范围内遵守比耳定律,室温下显色后,吸光度在110min内稳定。研究了30种外来离子的影响,并进行了高纯镍中微量锇的测定。     

鲁米诺－亮绿SF－过氧化氢－铜（Ⅱ）化学发光体系的研究

本文报道了鲁米格亮绿ＳＦ－过氧化氢。铜（Ⅱ）化学发光体系，建立了测定微量铜的化学发光新方法。相对标准偏差为２．４％（ｎ＝１０），检出限为１．６×１０￣－９ｍｏｌ·Ｌ￣－１。用于人发、茶叶及铜精矿样品中微量铜的测定，结果令人满意。     

磷钼酸铵-孔雀绿-PVA分光光度法测定钽粉中磷

提出了以磷钼酸铵-孔雀绿-PVA三元络合物体系测定金属钽粉中磷的方法,该体系表观摩尔吸光系数ε=8.19×104L.mol-1.cm-1,加标回收率为:99.3%~105%,方法的RSD为:5.9%。有效地解决了目前高纯钽粉中磷的分析难题,方法已应用于实际产品的分析中。     

偶合反应化学发光法测定痕量银的研究

本文报道了Ａｇ（Ⅰ）催化ｏ－ｐｈｅｎ和Ｋ４Ｆｅ（ＣＮ）６的配位体取代反应与Ｌｕｍｉｎｏｌ－Ｃｕ（ＣＮ）２－４的化学发光反应偶合测定痕量银的方法．方法的线性浓度范围为１×１０－１１～１×１０－７ｇ／ｍＬＡｇ，检出限为４×１０－１２ｇ／ｍＬＡｇ，用于水样分析，结果较为满意     

锌-硫氰酸盐-孔雀绿体系溶剂浮选机理及影响因素的探讨

本文通过对锌(Ⅱ)—硫氰酸盐—孔雀绿体系溶剂浮选过程的考察,提出了待测Zn~(2+)离子从水相被输送到有机相,可以用吸附机理和粘附机理来解释;同时还对影响锌溶剂浮选的主要因素:溶液的pH,气泡的大小和气体流速等进行了讨论。