UV irradiation enhances the bonding strength between citric acid-crosslinked gelatin and stainless steel

The effect of ultraviolet ray (UV) irradiation on the bonding strength between low carbon stainless steel 316 (SUS316L) and trisuccinimidyl citrate (TSC)-crosslinked alkali-treated gelatin (AlGelatin-TSC) was investigated. The UV irradiation effectively generated hydroxyl groups on the surface of SUS316L. The bonding strength between AlGelatin-TSC and SUS316L before UV irradiation was 0.345±0.007 MPa, and upon UV irradiation it increased to 0.750±0.069 MPa. In order to explain this enhanced bonding strength, the surface of SUS316L was examined using its water contact angle and X-ray photoelectron spectroscopy. Furthermore, the N 1s peaks derived from the TSC succinimidyl group were assigned to the surface of SUS316L after the immobilization of the TSC. This indicates that ester bond formation between the TSC active esters and the SUS316L hydroxyl groups contributed to the enhanced bonding strength. Therefore, UV irradiation and subsequent TSC immobilization is a simple way to functionalize biometal surfaces with various structures. This has practical applications for medical devices such as drug-eluting stents, dental implants, and metallic artificial bone.     

Effect of high pH column regeneration on the separation performances in reversed phase chromatography of peptides

Caustic regeneration procedures are often used in chromatographic purification processes of peptides and proteins to remove irreversibly bound impurities from the stationary phase. Silica-based materials are the most commonly used materials in reversed phase chromatography of peptides. Their limited chemical stability at high pH can be, however, problematic when high pH column regeneration (i.e. cleaning in place) is required. The effect of cleaning in place on the surface chemistry of the stationary phase has been investigated using the Tanaka test. It has been shown that the high pH treatment does not significantly affect the hydrophobicity of the material, but it strongly increases its silanol activity. A representative peptide purification process has been used to investigate the impact of cleaning in place on the separation performance. It has been shown that the caustic regeneration increases the peptide retention at high pH (pH 6.5), due to the interactions between the peptide and the negatively charged silanol groups. These unwanted interactions reduce the separation performances by decreasing the selectivity between the late eluting impurities and the main peptide. However, it has been shown that the effect of the silanol groups on the peptide adsorption and on the separation performance can be minimized by carrying out the purification process at low pH (pH ∼ 2). In this case, the silanol groups are protonated and their electrostatic interactions with the positively charged analyte (i.e. peptides) are suppressed. In these conditions, the peptide adsorption and the impurity selectivity is not changing upon high pH column regeneration and the separation performance is not affected.     

Corrosion behavior of 316 stainless steel for advanced high-temperature water-cooled nuclear plant

Corrosion occurs widely in the supercritical water system materials under high temperature and pressure. To select reliable candidate materials, corrosion behavior of many alloys was investigated. This study focused on investigating the corrosion behavior of 316 stainless steel (316 SS) in supercritical water (798 K/24 MPa). After exposed to SCW for 200 h, the oxidation kinetics, surface morphology, and diffusion of elements were investigated by weight measurement, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The surface of 316 SS showed isolated and discontinued oxide scales. The oxide scale was determined to be a monolayer layer, and the main composition was determined to be Fe–Cr-rich spinel with a few amounts of magnetite attached to the surface. A few pores due to pitting corrosion were found on the surface, and the oxidation mechanism was also investigated.     

Trends in product analysis for research in the pharmaceutical industry

Characterization of substances and formulations with respect to purity and stability is a major analytical chemical task during product development in the pharmaceutical industry. The importance of separation methods, especially liquid chromatography, is shown with some examples from work with omeprazole. The role of mass spectrometry (MS) for structure elucidation is emphasized. Dissolution testing comprises a large number of samples and adaptation to standardized procedures is important. Work is exemplified with dissolution testing of felodipine. Automation and robots with multivariate calibration are necessary approaches. Macromolecular characterization is exemplified from the fields of biomolecules and macromolecular excipients. Separation methods and MS are important tools. New challenges in the area of process analytical chemistry are discussed and chemometrics will play an important role. In all fields method validation is stressed, but should not require more power than necessary in a specification.     

离子色谱-直接电导法测定碱土金属和过渡金属离子

本文报道离子色谱-直接电导法测定碱土金属和过渡金属离子。研究了流动相pH值、乙二胺浓度及柠檬酸和酒石酸浓度对金属离子分离的影响。结果表明,以乙二胺-柠檬酸为流动相可以同时分离碱土金属和过渡金属离子。用乙二胺-酒石酸作为流动相可以分离碱土金属离子。方法检出限为0.09~1.88 mg/L,加标回收率为97.6%~98.7%。该方法用于叶面肥试样的分析,结果良好。     

Surface characterization and electrochemical corrosion behaviour of 304 stainless steel in aqueous media

A formulation consisting 100 ppm of 3-phosphonopropionic acid, 50 ppm of Zn²⁺ and 150 ppm of Tween 80 (polyoxyethylene sorbitan monooleate) offered 97.4% inhibition to the corrosion of 304 austenitic stainless steel immersed in a groundwater environment. This formulation functioned as a mixed inhibitor. The protective film was analysed by luminescence, XRD and FTIR spectra and pit morphology and was also observed by scanning electron microscopy. Electronic Publication     

AMT在青铜-柠檬酸体系中的缓蚀行为及其机理

用电化学方法、红外反射光谱法研究AMT(2-氨基-5-巯基-1,3,4-噻二唑)在青铜 -5％柠檬酸体系中的缓蚀行为和机理.结果表明,AMT能有效抑制青铜在柠檬酸中的腐蚀,属 混合型缓蚀剂.红外反射光谱表明,膜的最外层结构为Cu(Ⅰ)AMT,AMT中-NH2参与一价铜的络 合反应,环上离氨基最近的N参与配位. 缓蚀机理归因于成相膜的形成.     

Corrosion and biological behavior of nanostructured 316L stainless steel processed by severe plastic deformation

Nanostructured metals have different mechanical, chemical, and physical behaviors in comparison with the microstructured ones. Numerous research studies demonstrated that the biological behavior of nanostructured metallic implants was improved significantly. Concerning the nanostructured metals, decreasing the corrosion rate and the releasing of hazardous ions from metallic implants, and thus increasing the biocompatibility of implants are due to improving the native oxide layer. In the present study, nanostructured 316L stainless steel (biomedical grade) was manufactured via equal channel angular pressing (ECAP) method. To do so, the 316L stainless steel (SS) was exposed to the ECAP operation for eight passes. The impact of the ECAP process on corrosion behavior of SS samples was evaluated through performing the electrochemical polarization corrosion tests in Ringer's solution. Scanning electron microscopy was employed to study the surface morphology of common SS and ECAPed SS sample after the electrochemical polarization tests. Moreover, the biological behavior of the samples was evaluated via cell culture using fibroblast cells. The corrosion test results revealed a substantial decrease of corrosion rate from 3.12 (coarse‐grained sample) to 0.42 μA cm^?2 (for nanostructured). Furthermore, the cell proliferation in the interface of nanostructured sample and cell culture medium enhanced dramatically compared with the coarse‐grained one. The much better biological behavior of nanostructured SS sample in comparison with the coarse‐grained one is mostly due to the significant decrease of corrosion rate on the surface of SS samples, and the presence of much more chrome oxide on the surface of SS sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of hydrostatic extrusion on passivity breakdown on 303 austenitic stainless steel in chloride solution

The stability of the passive film formed on austenitic 303 stainless steel in the as-received state and after severe plastic deformation by hydrostatic extrusion (HE) leading to nanostructurization was investigated in an aggressive environment containing Cl⁻ ions by anodic polarization. Transmission electron microscopy (TEM) and stereological image analysis were used to examine structural changes introduced by HE. Surface analytical techniques such as light microscopy, scanning electron microscopy, Auger electron spectroscopy (AES), and scanning Auger microscopy (SAM) were used to characterize the morphology, grain size, and chemistry of the surface, including local characterization of nonmetallic inclusions and their surface before and after HE. SAM analysis revealed discontinuities of the passive oxide film on MnS inclusions. TEM and scanning transmission electron microscopy examinations confirm a drastic reduction of grain size accompanied by a distinct refinement of the size of sulfide inclusions in the HE matrix. These changes in the HE 303 stainless steel are apparently responsible for its reduced pitting resistance compared to the as-received material. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical–Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007.     

Performance of a photocatalytic hybrid system coupled with a stainless steel membrane for removal of humic acid

The objective of this study was to evaluate the performance of a photocatalysis/H₂O₂/metal membrane hybrid system in the degradation of humic acid. A metal membrane of nominal pore size 0.5 μm was used in the experiment for separation of TiO₂ particles. Hydrogen peroxide was tested as an oxidant. The efficiency of removal of COD_Cr and color increased rapidly for initial hydrogen peroxide concentrations up to 50 mg L⁻¹. The efficiency of removal of COD_Cr and color by 50 mg L⁻¹ initial hydrogen peroxide concentration was approximately 95 and 98%, respectively. However, addition of hydrogen peroxide over 50 mg L⁻¹ inhibited the efficiency of the system. Addition of hydrogen peroxide to a UV/TiO₂ system enhanced efficiency of removal of COD_Cr and color compared with no addition of hydrogen peroxide. This may be ascribed to capture electrons ejected from TiO₂ and to the production of OH radicals. Application of the metal membrane in the UV/TiO₂/H₂O₂ system enhanced the efficiency of removal of COD_Cr and color because of adsorption by the metal membrane surface and the production of OH radicals. By application of a metal membrane with a nominal pore size of 0.5 μm, TiO₂ particles were effectively separated from the treated water by metal membrane rejection. The photocatalytic metal membrane had much less resistance than the humic acid, TiO₂, and humic acid/TiO₂ because of the degradation of humic acid by the photocatalytic reaction.     

氢化物发生-原子吸收光谱法测定柠檬酸中微量铅

柠檬酸样品经硫酸处理及在550℃灼烧灰化,残渣溶于盐酸(5+95)溶液中。用铁氰化钾将溶液中铅(Ⅱ)氧化成铅(Ⅳ),然后再以硼氢化钾为还原剂,盐酸(1+99)溶液为载流,用氢化物发生-原子吸收光谱法测定铅含量。在优化的试验条件下,铅的质量浓度在20μg·L~(-1)以内与其吸光度呈线性关系,检出限(3σ)为2.6μg·L~(-1)。用此方法分析了3个柠檬酸样品,测定值的相对标准偏差(n=6)小于5%,加标回收率在90.5%～110.0%之间。     

柠檬酸铁（Ⅲ）络合物的光致变色现象与柠檬酸的测定

报道了柠檬酸铁（Ⅲ）络合物的光致变色现象并将其应用于微量柠檬酸（或盐）的测定。在ＰＨ１．８－２．５的酸性介质中，柠檬酸与Ｆｅ＾３＋生成的黄色络合物在光照下发生光致变色生成紫色络合物，其最大吸收波长为４９０ｎｍ；表观摩匀吸光系数ε为８０５Ｌｍ．ｍｏｌ＾－１．ｃｍ＾－１，络合物的组成比为１：１。方法的线性范围为０－－２５０ｍｇ／Ｌ，用此法测定了几种饮料的中的柠檬含量，结果令人满意。     

席夫碱缓蚀剂的合成及其对碳钢材料缓蚀性能

采用失重法和电化学方法研究了2种席夫碱类缓蚀剂N,N′-二水杨醛基-1,2-乙二亚胺（SB-Ⅰ）和水杨醛基吡啶-2-亚胺(SB-Ⅱ)在1 mol/L盐酸溶液中对A3碳钢的缓蚀性能。 失重实验表明,SB-Ⅰ和SB-Ⅱ在1 mol/L盐酸溶液中的浓度为20 mmol/L时,缓蚀效率分别达85%和92%。 经三电极体系极化曲线和交流阻抗谱测定实验表明,缓蚀性能是由于碳钢材料表面为缓蚀剂分子吸附所致,二者均属阴极型缓蚀剂。     

Current experiences with a quality management system for non-clinical research and development in pharmaceutical industry

Quality management is one of the most important issues in pharmaceutical research as it determines the validity and reliability of data, data and data evaluation being the central products of all research activities. In this business it is of outstanding importance to generate valid data for the assessment of drug development candidates to assure that the huge financial investment, which is based on such assessments, can be successful. Efficacy and safety of products are the final goals of such developments. Therefore, Merck/Merck Serono implemented an additional specifically developed quality management system that covers all areas and locations in Merck Serono Research that were not yet regulated by an existing regulatory quality management system, e.g. GLP (Good Laboratory Practice). The system is known under the name Merck Serono Research-Quality Management System (MSR-QMS). Thus, we describe the implementation process of MSR-QMS as a research specific quality management system in a global company. Furthermore, the implementation process in one specific research department will be highlighted. Using a practical example, the validation of an analytical instrument in a MSR-QMS-regulated research laboratory will be shown and compared to a validation process in a strictly GLP-regulated area. A summary of the experiences with the new quality system will complete this article and the advantages of high quality research results in industry will be discussed.     

Kinetic determination of iodide in pharmaceutical and food samples

A kinetic method for the determination of iodide based on its inhibitory effect on the Pd(III) catalysed reaction between ethylenediaminetetraacetic acid (EDTA)-Co(III) and the hypophosphite ion is described. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance at 540 nm. Under the optimum experimental conditions of 2.6 x 10(-3) mol dm(-3)Co(III)-EDTA, 0.4 mol dm(-3)H2PO2-, pH 3.2 (adjusted with Britton-Robinson buffer), 0.57 micrograms ml(-1) Pd(III) and 20 +/- 0.2 degrees C, iodide was determined in the range 2-28 ng ml(-1). The method was applied to the determination of iodide in pharmaceutical products, iodinated salts, cow's milk and infants' powdered milk.     

Stopped-flow determination of iodide in pharmaceutical and food samples

The iodide-catalysed reaction between cerium(IV) and arsenic(III) has been studied using a modular stopped-flow system. The features of both the stopped-flow and conventional kinetic methods have been compared by using the same instrument. The stopped-flow method has a wider linear range and is faster than the conventional kinetic method and has been applied satisfactorily to the photometric determination of iodide in pharmaceutical preparations, table salt and cow's milk. The results obtained show that the stopped-flow method is simple, inexpensive and rapid and requires no sophisticated equipment. In addition, its high sampling rate makes it particularly suitable for the routine determination of iodide.     

Corrosion inhibition and mechanism of mild steel in hydrochloric acid by ceftriaxone and amoxicillin

Corrosion inhibition of mild steel in 1 mol/L HCl by amoxicillin and ceftriaxone in the concentration range of 1.00×10-5-1.00×10-2 mol/L has been studied using weight loss,electrochemical potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM) and quantum chemistry tests at 298 K.The weight loss experiment showed that the inhibition efficiency increased with amoxicillin and ceftriaxone concentrations to attain the maximums of 80.3% and 94.1%,respectively at...