Fingerprint Analysis of Insulin: Application in Stability Studies of Pharmaceutical Preparations

The identification of a protein drug and the determination of its purity requires the use of several analytical methods. One identification probe used is the proteolysis of insulin with Staphylococcus aureus protease. This method yields a characteristic pattern of peptide fragments (“fingerprint”) which could be separated by reverse-phase high-performance liquid chromatography (HPLC) with gradient elution and ultraviolet detection. This probe could be used as a stability-indicating method for peptide and proteins, supplementing other traditional methods as reverse-phase (RP) and size-exclusion (SE) HPLC. Proteolysis of commercial human insulin preparations stored under different conditions produces modified fingerprints versus reference standard digested samples. Results vary as a function of the type of preparation and storage conditions since the degradation products detected by SE-HPLC are different.     

土壤环境中钢的杂散电流腐蚀研究

杂散电流可以造成金属的电解腐蚀侵害,在实验室模拟装置中,采用动电位扫描和恒电流极化法模拟杂散电流,研究了其对土壤环境中钢材的电解腐蚀行为,表征了其腐蚀产物及其表面钝化膜的形貌,探讨了腐蚀机理。结果表明,A3、16Mn和X70钢在土壤环境中的动电位扫描极化过程变化趋势基本相同;在恒电流阳极极化反应初期钢发生阳极溶解过程,待反应达到一定程度后,金属电极表面生成钝化膜,阳极极化电压发生突跃,钝化膜的生成与溶解交替过程造成阳极极化电压的振荡。     

Cd_2SnO_4等四种半导体薄膜制备及性能研究

采用喷涂热解法制备了以Cd2SnO4为代表的四种半导体薄膜，即Cd2SDO4，In2SnO5，TiSnO4及Zn2SnO4。测试了薄膜的半导体、光学和电学性能，得到了In2SnO5，Cd2SpO4薄膜电阻率的范围在10（－3）Ω·cm和高的透射比（可见光）；TiSnO4薄膜高的反射比（红外光）；同时，比较溅射法对结果进行了讨论。     

钡镁锰矿合成及在水溶液中电化学性质研究

合成了一种二氧化锰电池正极材料.用改进的碱性条件下合成晶型良好的纳米δ     

钡镁锰矿合成及在水溶液中电化学性质研究

合成了一种二氧化锰电池正极材料．用改进的碱性条件下合成晶型良好的纳米δ－ＭｎＯ_２,合成出了含 Ｍｇ^２＋的钡镁锰矿（Ｔｏｄｏｒｏｋｉｔｅ）,经 ＸＲＤ、 ＴＥＭ测试表明其为粒度均匀的纳米大隧道（３×３）ＭｎＯ_２,并在碱性和中性电液中对样品进行恒流放电,循环伏安等电化学性能测试,结果表明循环稳定性良好。     

Relation Between Polymorphic Transformation Pathway During Grinding and the Physicochemical Properties of Bulk Powders for Pharmaceutical Preparations

Abstract

The polymorphic transformation pathway during grinding of cephalexin (CEX), chloramphenicol palmitate (CPP) and indomethacin (IMC) were investigated. CEX was converted into noncrystalline solid at room temperature. The meta-stable forms B and C CPP was transformed into stable form A at room temperature. IMC was transformed into noncrystalline solid during grinding at 4°C, but it transformed into meta-stable form a during grinding at 30°C. The melting point (mp) of CPP and IMC were about 90°C and 160°C, respectively. CEX does not have the mp, but have the decomposition point at 190°C. The mp of CEX is higher than the decomposition point. The order of the mp for these drugs is CPP < IMC < CEX. The proportional relation between the mp and the glass transition point of the drugs had reported, therefore, in general the higher mp material has the higher glass transition point. The order of the stability for a noncrystalline solids of these drugs is CPP < IMC < CEX. The noncrystalline solid of CEX is very stable at 35°C under lower than 66% of relative humidity. The noncrystalline solid of CPP was very unstable at about 20°C, therefore, it transformed into a crystalline form very rapidly. The noncrystalline solid of IMC was stable at 4°C, but it was unstable at 30°C, therefore, after grinding it transformed into a form. These results suggest that there is a very important relation between the transformation pathway of the crystalline form during grinding and the physicochemical properties. The transformation pathway is controlled by the stability of noncrystalline solid and the presence of meta-stable crystalline form.     

水相中银纳米粒子的制备及动力学行为研究

以油酸钠为表面活性剂、AgNO3为前驱剂、N,N-甲基甲酰胺(DMF)为还原剂,在水相体系制备银纳米粒子.采用紫外-可见分光光度计测定了不同反应时间银纳米粒子的吸收曲线,系统地考察了反应温度以及DMF加入量等因素对银纳米粒子生成过程动力学行为的影响.结果表明,未加DMF时,该反应体系不能生成银纳米粒子,随着DMF加入量的增加和反应温度的升高,体系中银纳米粒子的吸收强度逐渐增大,在100℃、DMF加入量为3mL时,银纳米粒子的吸收强度大幅度提高.透射电子显微镜的结果表明,所得的银纳米粒子具有球形形貌,且具有较窄的尺寸分布.     

低合金耐候钢在周期性交替条件下的腐蚀行为

用去离子水和3.5%NaCl模拟和缓与苛刻的腐蚀环境,进行腐蚀环境交替变换的实验研究低合金耐候钢的大气腐蚀行为。结果表明,在和缓或苛刻的单一腐蚀条件下低合金耐候钢都不易形成致密的锈层,但交替腐蚀1个周期后,形成了敛密的保护性锈层。在初期腐蚀环境苛刻、后期腐蚀环境和缓的试验条件下,与相反的试验条件相比,耐候钢能更快地形成更致密的锈层。     

Buckling and Postbuckling Behavior of Functionally Graded Nanotube-Reinforced Composite Plates in Thermal Environments

This paper investigates the buckling and postbuckling of simply supported, nanocomposite plates with functionally graded nanotube reinforcements subjected to uniaxial compression in thermal environments. The nanocomposite plates are assumed to be functionally graded in the thickness direction using single-walled carbon nanotubes (SWCNTs) serving as reinforcements and the plates' effective material properties are estimated through a micromechanical model. The higher order shear deformation plate theory with a von Kármán-type of kinematic nonlinearity is used to model the composite plates and a two-step perturbation technique is performed to determine the buckling loads and postbuckling equilibrium paths. Numerical results for perfect and imperfect, geometrically mid-plane symmetric functionally graded carbon nanotube reinforced composite (FG-CNTRC) plates are obtained under different sets of thermal environmental conditions. The results for uniformly distributed CNTRC plate, which is a special case in the present study, are compared with those of the FG-CNTRC plate. The results show that the buckling loads as well as postbuckling strength of the plate can be significantly increased as a result of a functionally graded nanotube reinforcement. The results reveal that the carbon nanotube volume fraction has a significant effect on the buckling load and postbuckling behavior of CNTRC plates.     

New Interpretation of the Concentration Dependence of the Compressibility of Aqueous Solutions of Nonelectrolytes

The parabolic-like plots of compressibility versus concentration of nonelectrolytes (ethanol as the example) in water are explained and described assuming the hydrate formation equilibrium reaction. Only two fitted parameters, the hydration number n _h and the cumulative formation constant of the hydrate b_nh{\beta_{n_{\rm h}}}, are used to reproduce the experimental data, including the minima of the adiabatic compressibility k_S{\kappa_{S}} versus composition at low solute contents. Another discussed option is a set of subsequent equilibrium reactions of hydration from which formation constants can also be determined. Calculations were performed for the water–ethanol system, and the results were compared with those obtained by a model recently developed by the authors.     

Corrosion-Electrochemical Behavior of M1 Copper in Aqueous Ethylene-Glycol Media

In aqueous ethylene-glycol media, M1 copper oxidizes to Cu⁺ ions. In the course of corrosion, dissolved oxygen oxidizes ethylene glycol and Cu⁺ ions to Cu^{2 +} ions, which, together with ethylene glycol and the products of its oxidation, form complex compounds. In the case of deep ion-exchange purification of a water-ethylene-glycol heat carrier (ρ = 100 kΩ · m), the maximum value of the coefficient of protective action is 70%. With decrease in the concentration of dissolved oxygen to 1 g/m³, under conditions of minimum purification ρ = 5 kΩ · m), this parameter constitutes 77% and grows to 97% for a specific electric resistance of the heat carrier of 50 kΩ · m. Combining both methods of the removal of corrosion-active admixtures (dissolved oxygen and the products of copper and ethylene glycol oxidation), one can enhance substantially the corrosion resistance of copper in water-ethylene-glycol heat carriers.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 1, pp. 19 – 26, January – February, 2005.     

Mechanoelectrochemical Behavior of Pure Magnesium and Magnesium Alloys Stressed in Aqueous Solutions

A new synergistic effect of corrosion and stress on the viscoelasticity of pure magnesium and magnesium alloys has been shown. This phenomenon named corrosion creep has been studied in 99.9653% Mg, die-cast AZ91D (Mg–9% Al–1% Zn), AM50 (Mg–5% Al–0.4% Mn), and AS21 (Mg–2.3% Al, 0.23% Mn, 1.10% Si) alloys. Creep tests were carried out at 25°C in air and in the borate buffer aqueous solution (pH 9.3). It is found that the highest sensitivity to creep in the corrosive environment is observed in the alloy with the highest Al content. This agrees with the data obtained earlier in the study of mechanoelectrochemical behavior and corrosion fatigue of Mg alloys. However, in air, the creep behavior of all alloys at room temperature is approximately the same. Creep life of pure magnesium and its alloys significantly decreases in a corrosive environment. Corrosion-creep cracks filled with magnesium hydroxide particles were observed by SEM–EDS analysis at the surface of AS21 alloy. The thickness of the oxide layer defined by AES in samples of AZ91D, AM50, and AS21 alloys placed for 2 h into the borate solution amounts to 540, 1320, and 1440 nm, respectively. This can be explained with the account for surface phenomena.     

双功能化SBA-15的制备及对水中Ni2+的吸附行为

分别以硅烷偶联剂和EDTA-2Na为改性剂,采用后嫁接法,制备出双功能化介孔二氧化硅SBA-15。利用傅里叶红外光谱仪、N2吸附-脱附对样品结构进行了表征,并讨论了吸附热力学特性、吸附动力学特性及吸附等温特性。结果表明,双功能化SBA-15吸附水中Ni 2+时在180min内可以达到吸附平衡,吸附过程为化学吸附与物理吸附共存的过程,吸附过程符合拟二级动力学方程,吸附等温线符合Langmuir模型,基于Langmuir模型计算得出35℃时最大吸附量为31.25mg·g-1。     

《快递包装重金属与特定物质限量》标准解读

目的 重点研究《快递包装重金属与特定物质限量》标准中有毒有害的环保指标的来源和检测方法,并介绍制定这一标准的背景。方法 基于SCQA（背景—问题—疑问—答案）的逻辑思路,梳理标准制定的过程,总结快递包装涉及的材质类型,按材质类型理清每种材质的环保限值指标,并给出标准发布实施的思考建议。结论 作为首个邮政寄递业的国家强制性标准,《快递包装重金属与特定物质限量》标准规定了快递包装用纸类、塑料类和纺织纤维类包装产品中重金属与特定物质限量的底线要求和红线要求,并描述了相应环保指标的试验方法,明确了快递封装用品的绿色环保指标和限量值,要求快递包装绿色无害化发展。     

Behavior of Alkali Metal and Ammonium Salts in Nanofiltration of Their Aqueous Solutions

Radiochemistry - The behavior of salts (chlorides, nitrates, sulfates, phosphates, borates, ferri- and ferrocyanides) of various alkali metals (Li, Na, K, Cs) and ammonium in the course of...     

An Object-oriented Interpretation of the EAT System

In a previous paper we characterized, in the Category Theory setting, a class of implementations of Abstract Data Types, which has been suggested by the way of programming in the EAT system. (EAT, Effective Algebraic Topology, is one of Sergeraerts systems for effective homology and homotopy computation.) This characterization was established using classical tools, in an unrelated way to the current mainstream topics in the field of Algebraic Specifications. Looking for a connection with these topics, we have found, rather unexpectedly, that our approach is related to some object-oriented formalisms, namely hidden specifications and the coalgebraic view. In this paper, we explore these relations making explicit the implicit object-oriented features of the EAT system and generalizing the data structure analysis we had previously done.     

钢芯铝绞线的铝线在NaCl溶液中的腐蚀行为

钢芯铝绞线正常运行温度达80℃,受到环境中盐离子的严重腐蚀。采用Tafel直线外推法、电化学阻抗谱法及加速腐蚀试验法,研究了钢芯铝绞线的铝线在不同浓度NaCl溶液中的腐蚀行为,利用SEM和XRD等表征了其腐蚀表面状态及产物形貌。结果表明:随着NaCl浓度的升高,铝线的自腐蚀电位负移,极化电阻变小,腐蚀速率增大,当NaCl为70 mg/L时腐蚀速率急剧增加,是10 mg/L NaCl时的40倍;腐蚀产物及钢芯表面镀锌层可抑制铝线的腐蚀,铝线腐蚀后的表面出现大量的"麻点"及腐蚀坑,白色的腐蚀产物主要由Zn0.64Al0.36(OH)2(CO3)0.18.0.86H2O组成。     

Aqueous Solubility of Diclofenac Diethylamine in the Presence of Pharmaceutical Additives: A Comparative Study with Diclofenac Sodium

Aqueous solubility of diclofenac diethylamine (DDEA), a nonsteroidal anti-inflammatory drug currently formulated as a topical emulgel, was studied in the presence of pharmaceutical additives and compared with diclofenac sodium (DS). Electrolytes at low concentrations exhibited a salting-in effect on DDEA with peak solubility that was attributed to the association of DDEA into micelles, followed by a salting-out effect at higher concentrations, by which structure formation by DDEA molecules increased and precipitation occurred. For DS, which is not capable of forming micelles, the salting-out effect was dominant due to the common ion effect. Cosolvents displayed significant enhancement in solubility of both salts except glycerol, which showed a slight increase in solubility of DDEA and a decrease in solubility of DS due to transformation into the less soluble hydrate form. Ethanol and polyethylene glycol (PEG) 400 cosolvent systems at all concentrations showed positive deviations from the log-linear solubility equation. In the case of propylene glycol (PG) cosolvent systems, negative deviations were observed at low volume fractions of cosolvent, while positive deviations were observed at high volume fractions of cosolvent for DS and DDEA. The parent drug, being less ionizable and highly nonpolar, showed negative deviations up to 90% PG content. Thus, the positive deviations for DS and DDEA could be attributed to the more ionizable carboxylic group and its higher ability for hydrogen bonding at higher fractions of cosolvent. Polyvinylpyrrolidone (PVP) and PEG4000 or PEG6000 enhanced the solubility of DS and DDEA, with PVP exerting higher solubilizing efficiency and DS showing better solubility than DDEA. Solubilities of DS in Tween 80 (T80) and Pluronic F-127 (PF127) aqueous solutions were almost similar, while the solubility of DDEA in the presence of T80 was higher than the solubility in the presence of PF127. DS appeared to be located more in the polyoxyethylene mantle of the micelles, while DDEA was located more in the core of the micelles.     

Effects of Oils and Pharmaceutical Excipients on the Bioavailability of Ampicillin Orally Administered,Different Oily and Aqueous Suspensions in Rabbit

Abstract

The in vivo bioavailability and in vitro drug-release studies of ampicillin trihydrate in different oily and aqueous suspensions have been investigated. In addition, partition, solubility, and rheological measurements have also been carried out. The in vivo experimental design was based on a 6 × 6 latin square using the rabbit as the test animal. The bioavailability of ampicillin was determined using the plasma levels, which were measured microbiologically. Results of the study showed that oily and sucrose-containing aqueous formulations enhanced the extent of ampicillin absorption, although not statistically significantly, but was close to the borderline of significance. Ampicillin appears to be absorbed at essentially the same rate from both aqueous and oily formulations. The latter showed plasma-level time curves with biphasic absorption and are likely to produce prolonged plasma concentrations of ampicillin because of the effects of enterohepatic recycling. Viscosity appears to play an insignificant role in the results obtained since the bioavailability parameters correlate poorly with the viscosity except C_max. It is suggested that enhancement in the bioavailability of ampicillin is due to the decrease in the gut transit rate brought about by the oil which predominates and masks the other effects of viscosity and osmotic effects of sucrose. The existence of a correlation between the in vitro drug-release rate (t_50%) and viscosity and the lack of a correlation between in vivo and in vitro parameters support the above suggestion and indicate that traditional dissolution rate tests, such as flask-stirrer method, are unsatisfactory as bioavailability indicators when applied to dosage forms that caused marked changes in physiological factors like GER and biliary excretion.