Polymerization kinetics of methylmethacrylate by oxidation: Reduction system using cerium(IV)/lactic acid in aqueous medium

The kinetics of polymerization of methylmethacrylate initiated by cerium(IV)–lactic acid redox system was studied in an aqueous medium in the temperature range of 25–50°C. The rate of polymerization (R_p) and the rate of cerium(IV) disappearance have been measured. The effects of some water‐miscible organic solvents, cationic, anionic, nonionic surfactants, and complexing agents on the rate of polymerization were investigated. The temperature dependence of the rate was studied, and the activation parameters were computed using the Arrhenius and Eyring plots. The effects of inorganic and organic solvents on polymerization were also investigated. All of them depressed both the initial rate and limiting conversion. A mechanism consistent with the experimental data, involving cerium(IV)–lactic acid complex formation, which generates free radicals, is suggested. The chain termination step of the polymerization reaction is by mutual interaction of the growing macromolecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3498–3505, 2007     

Polymerization kinetics of acrylonitrile by oxidation: Reduction system using potassium persulfate/ascorbic acid in an aqueous medium

The kinetics of acrylonitrile polymerization initiated by free radicals formed in situ in a potassium persulfate/ascorbic acid redox system was investigated in an aqueous sulfuric acid medium in the temperature range of 40–70°C. The rate of polymerization and the rate of the disappearance of potassium persulfate were measured. A kinetic scheme involving the production of initiating radicals from the oxidation of ascorbic acid by potassium persulfate ions and termination exclusively by the interaction of chain radicals with persulfate ions is proposed. The effects of some water‐miscible organic solvents on the rate of polymerization were investigated. The temperature dependence of the rate was studied. A possible mechanism consistent with the experimental data is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mesoporous aluminophosphate materials: influence of method of preparation and iron loading on textural properties and catalytic activity

In this paper the influence of the method of preparation and the iron loading on the textural properties and surface acidity of Iron aluminophosphates (FeAlP), [Fe _x Al_0.95P₁, x = 0.01 mol−0.1 mol] was studied in order to learn how the preparation conditions and iron loading affect catalyst activity in transesterification reaction between diethyl malonate and benzyl alcohol. The catalysts were characterized by BET surface area, N₂ sorption studies, NH₃-TPD pXRD, SEM, and. FT-IR. Significant differences in the texture, surface acidity and adsorptive properties of FeAlP catalysts were found showing the influence of the preparation conditions and iron loading on the textural and surface properties of these catalysts. The textural and surface properties are correlated in the transesterification reaction between diethyl malonate and benzyl alcohol. FeAlP with 0.025 mol iron loading prepared by drop wise addition of ammonia, resulted a mesoporous material with uniform pore diameter (5–18 nm), higher surface area and higher surface acidity and hence catalytic activity towards the formation of Dibenzyl malonate. Fast addition of ammonia produced nonuniform porous material with lower surface acidity and low transesterification activity. Urea hydrolysis method yielded nonuniform porous materials with low surface area as well acidity.     

Esterification of stearic acid with p-cresol over modified Indian bentonite clay catalysts

The esterification of stearic acid with p-cresol using modified Indian bentonite clay catalysts has been reported. The reaction was studied over exchanged clays, acid activated clays, exchanged acid activated clays, aluminium pillared clay, aluminium pillared acid activated clay, molecular sieve Al-MCM-41, zeolite Hβ, ZrO₂, S-ZrO₂, p-TSA, montmorillonite K10, and montmorillonite KSF in o-xylene for 6 h. The catalysts were characterized by X-ray diffraction and surface area measurements. The acidity was determined by n-butylamine back-titration method and DRIFTS after pyridine adsorption. Acid activated Indian bentonite (AAIB) was found to be a better catalyst compared to other catalysts in the esterification of stearic acid with p-cresol.     

Packaging and storage studies on double-filtered groundnut oil

Packaging and storage studies of double-filtered groundnut oil was carried out in different multilayer film pouches based on non-nylon, nylon and polyester (PET) layers and PET bottles at 27° C and 65% relative humidity (RH) and 38° C and 90% RH. The groundnut oil keeps better in multilayer film pouches consisting of nylon and PET films and PET bottles than in non-nylon-based film pouches under both conditions.

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Verpackung und Lagerung von doppelt filtriertem Erdnußöl

Zusammenfassung Es wurden Untersuchungen über die Lagerfähigkeit von doppelt filtriertem Erdnußöl in Polyesterflaschen und in Beuteln aus Verbundfolien mit und ohne Nylon sowie mit Polyester als Barriereschicht durchgeführt. Die Lagerung fand bei 27 °C, 65% relative Feuchtigkeit und 38 °C, 90% relative Feuchtigkeit statt. Die Haltbarkeit des Öls in den Flaschen und Beuteln mit Barriereschichten war wesentlich besser als in den Beuteln ohne Nylon-Schicht.

     

Uptake of permanganate from aqueous environment by surfactant modified montmorillonite batch and fixed bed studies

Organo-clay was prepared by incorporating different amounts (in terms of CEC, ranging from 134?C840 mg of quaternary ammonium cation (QACs) such as hexadecytrimethylammonium bromide ([C₁₉H₄₂N]Br) into the montmorillonite clay. Prepared organo-clays are characterized by CHN analyser and XRD to measure the amount of elemental content and interlayer spacing of surfactant modified clay. The batch experiments of sorption of permanganate from aqueous media by organo-clays was studied at different acidic strengths (pH 1?C7). The experimental results show that the rate and amount of adsorption of permanganate was higher at lower pH compared to raw montmorillonite. Laboratory fixed bed experiments were conducted to evaluate the breakthrough time and nature of breakthrough curves. The shape of the breakthrough curves shows that the initial cationic surfactant loadings at 1??0 CEC of the clay is enough to enter the permanganate ions in to the interlamellar region of the surfactant modified smectile clays. These fixed bed studies were also applied to quantify the effect of bed-depth and breakthrough time during the uptake of permanganate. Calculation of thermodynamic parameters shows that the sorption of permanganate is spontaneous and follows the first order kinetics.     

Fertility in mice requires X-Y pairing and a Y-chromosomal "spermiogenesis" gene mapping to the long arm

There is accumulating evidence that the mammalian Y chromosome, in addition to its testis-determining function, may have other male limited functions, particularly in spermatogenesis. We have previously shown that the short arm of the mouse Y carries information needed for spermatogonial proliferation. This information, together with the testis-determining gene Sry, is contained within the Y-derived sex reversal factor Sxra. XO males carrying a copy of Sxra attached to the X chromosome are nevertheless sterile owing to an almost complete arrest during the meiotic metaphase stages. Here we show that this meiotic block can be overcome by providing a meiotic pairing partner (with no Y-specific DNA) for the XSxra chromosome. However, this does not restore fertility because the sperm produced all have abnormal heads. It is concluded that the Y-specific region of the mouse Y chromosome long arm includes information essential for the normal development of the sperm head.     

Enhanced security‐aware technique and ontology data access control in cloud computing

Nowadays, security and data access control are some of the major concerns in the cloud storage unit, especially in the medical field. Therefore, a security‐aware mechanism and ontology‐based data access control (SA‐ODAC) has been developed to improve security and access control in cloud computing. The model proposed in this research work is based on two operational methods, namely, secure awareness technique (SAT) and ontology‐based data access control (ODAC), to improve security and data access control in cloud computing. The SAT technique is developed to provide security for medical data in cloud computing, based on encryption, splitting and adding files, and decryption. The ODAC ontology is launched to control unauthorized persons accessing data from storage and create owner and administrator rules to allow access to data and is proposed to improve security and restrict access to data. To manage the key of the SAT technique, the secret sharing scheme is introduced in the proposed framework. The implementation of the algorithm is performed by MATLAB, and its performance is verified in terms of delay, encryption time, encryption time, and ontology processing time and is compared with role‐based access control (RBAC), context‐aware RBAC and context‐aware task RBAC, and security analysis of advanced encryption standard and data encryption standard. Ultimately, the proposed data access control and security scheme in SA‐ODAC have achieved better performance and outperform the conventional technique.     

Kinetic studies on free radical polymerization of acrylonitrile,initiated by chloramine‐T/hydrogen peroxide redox system

The Kinetics of polymerization of Acrylonitrile initiated by chloramine‐T/H₂O₂ Redox System was studied in aqueous medium in the temperature range of 35–50°C. The effects of variations such as [Monomer], [CAT], [H₂O₂], temperature, and chloramine‐T disappearance (?R_m) were measured. The effect of some water‐ miscible organic solvents and surfactants on the rate of polymerization was investigated. The polymerization process is initiated by the free radical arising from oxidation of H₂O₂ by chloramine‐T and terminated by the mutual combination of the growing polymer radicals. Based on the kinetic results, a suitable reaction scheme is proposed and discussed for the various rates of polymerization and thermodynamic parameters were evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5877–5883, 2006