Tensile modulus modeling of carbon‐filled nylon 6,6 and polycarbonate‐based resins

Electrically and thermally conductive resins can be produced by adding conductive fillers to insulating polymers. Mechanical properties, such as tensile modulus, are also important. This research focused on performing compounding runs followed by injection molding and tensile testing of carbon‐filled nylon 6,6 and polycarbonate‐based resins. The three carbon fillers investigated included an electrically conductive carbon black, synthetic graphite particles, and a milled pitch–based carbon fiber. For each polymer, resins were produced and tested that contained varying amounts of these single‐carbon fillers. In addition, combinations of fillers were investigated by conducting a full 2³ factorial design and a complete replicate in each polymer. These tensile modulus experimental results were then compared to results predicted by several different models. For the composites containing only one filler type, the Nielsen model with the modified Ψ term provided the best prediction of the actual experimental values. For the composites containing more than one filler type, a new parameter, which includes the vibrated bulk density (VBD) of the fillers, was incorporated into the Nielsen model with the modified Ψ term. This model with the new VBD parameter provided the best estimate of experimental tensile modulus for composites containing multiple‐filler types. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1716–1728, 2003     

Growth ofCururbita maxima L. plants in the presence of the cycloartenol synthase inhibitor U18666A1

Squash, like other Cucurbitaceae, have unique sterol profiles that offer an excellent opportunity to examine the relationship between sterol biosynthesis and plant growth. To determine the effect of sterol biosynthesis inhibition on squash growth, Cucurbita maxima seedlings with and without cotyledons were subjected to increasing concentrations of the cycloartenol synthase (EC 5.4.99.8) inhibitor 3β-(2-diethylaminoethoxy) androstenone (U18666A). Inhibition of shoot growth was concentration-dependent (from 0, 2, 5, 10, and 20 μM); plants with intact cotyledons grew to 26.4, 23.7, 21.6, 20.0, and 15.6 cm, respectively, at the above inhibitor concentrations, compared to 25.5, 19.4, 17.0, 12.0, and 11 cm for plants with severed cotyledons. In plants with severed cotyledons, 10 and 20 μM U18666A caused rapid necrosis of the first two, newly emerged, primary leaves, and halted new leaf formation. Secondary root formation was initially affected at all inhibitor concentrations regardless of whether cotyledons were present or not. Vegetative tissue showed a decrease in the accumulation of the major squash sterol, 7, 22-stigmastadienol, accompanied by increased accumulation of minor sterol components. Sterol profiles in cotyledons were unaltered. The data show that sterols are crucial for maintaining plant growth and viability, but do not address the cotyledonary effect on growth with respect to sterol biosynthesis. Based on a paper presented at the Symposium on the “Regulation of Biosynthesis and Function of Isopentenoids”, Atlanta, Georgia, May 1994.     

Mechanisms of degradation of cotton and effects of mercerization-stretching upon the course of these mechanisms,part VII. Characterization of microstructural differences between scoured cotton and slack mercerized-stretched cottons

Conditions were established to introduce almost equal and reproduciple amounts of diethylaminoethyl (DEAE) substituents into the molecular structure of scoured cotton (substrate I), slack mercerized cotton (substrate II), slack mercerized-stretched (94%, substrate III), and slack mercerized-stretched (103%, substrate IV) cotton. Similarities between the original structures of these substrates before and after the chemical modification were assessed by X-ray analysis. Comparison between the DEAE cottons and the corresponding unmodified cottons upon acid hydrolysis with respect to moisture regain, loss in weight and degree of polymerization was also made. Chemical analysis was used to study the compositions and structures of the hydrolyzates (i.e., hydrocelluloses and solublized fractions) resulting from hydrolysis of the modified cottons with 2.5 N HCl under reflux for different lengths of time. Studies of rates of hydrolysis of the cellulose, rates of removal of substituted glucoses and rates of removal of individual types of substituted glucose units were considered as means to provide information regarding: (a) distribution of DEAE substitutents throughout the structure of cellulose, (b) nature of accessible regions where the DEAE substituents are developed, and (c) selective availability of the hydroxyl groups at C-2, C-3 and C-6 of the D-glucopyranosyl units in the cellulose elementary fibril.     

Improving the dyeing properties of textiles via utilization of redox systems. I. Dyeing of wool and wool/polyacrylic blend fabrics with acid dye

Dyeing of wool and wool/polyacrylic fabrics with an acid dye, namely, Kiton Scarlet 4 R, was carried out in absence or presence of different redox systems. The latter were based on sodium, potassium, or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, sodium thiosulphate, potassium pyrosulphite or thiourea as reductant. Regardless of the redox system used, the colour strength was far greater in presence than in absence of the redox system. Except in case of potassium periodate/glucose redox system, increasing the oxidant concentration up to 0.03 mol/l caused significant enhancement in colour strength. The same was observed upon increasing the temperature from 30 to 60°C as well as the time from 10 to 40 minutes. It is postulated that presence of the redox system alters the mode of dye attachment to the substrate. Association of the dye with the substrate, wool in particular, seems to involve covalent bonding beside the usual salt-linkage. Hence the approach presented is advantageous in producing dyeings with much higher colour strength and dye fixation at relatively low temperature.     

Improving the dyeing properties of textiles via utilization of redox systems. II. Dyeing of nylon-6 with acid dye

Redox systems based on potassium, sodium or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, thiourea, sodium thiosulphate or potassium pyrosulphite as reductant were incorporated in the dyeing bath of nylon-6 under a variety of conditions. An acid dye, namely Kiton Scarlet 4 R was used. The colour strength and dye fixation enhanced outstandingly in presence of the redox system, depending upon kind and concentration of the redox components. Raising the dyeing temperature from 30 to 60°C caused significant improvement in colour strength. The same holds true for duration of dyeing up to 60 min. Beside association of the dye with nylon-6 by salt-like bond, a free radical mechanism was suggested.     

Attitudes towards mobile banking: are there any differences between users and non-users?

Extant research has focused on monitoring the behaviour of people who use mobile banking (MB) but it has paid little attention to understanding the impact of information technology usage behaviour due to cultural differences. Humans are the weakest link in information technology adoption; past research has shown that not all users are predisposed to change their behaviour radically and adopt new channels of banking. This paper examines the demographic patterns of users and non-users of MB. The paper also investigates the attitudinal influences of users and non-users of MB based on innovation attributes. Using empirical research, the study identifies constructs of innovation attributes that were perceived to be significantly different among the users and non-users of MB. The study provides valuable insights into MB in Saudi Arabia that have not been previously investigated. From a practical point, findings of this study will be particularly useful to banks, financial institutions and telecommunication service providers.     

Degradation of 4-chloro-2-methylphenol in aqueous solution by electro-Fenton and photoelectro-Fenton processes

Degradation of 4-chloro-2-methylphenol (PCOC), a refractory toxic chemical emitted to the environment from the industrial production of phenoxy herbicides was studied in aqueous solution. Electro-Fenton and photoelectro-Fenton processes were used as the degradation methods. H₂O₂, produced by the reduction of oxygen at carbon cathode reacted with dissolved metal ions to form hydroxyl radicals, which in turn reacted with PCOC sequentially to degrade the aromatic ring. The effects of using different [Fe²⁺]/[PCOC]₀ and the effect of replacing Fe²⁺ by Mn²⁺ ion have been examined. It was found that degradation rate was increased with increasing [Fe²⁺]/[PCOC]₀ ratio from 2 to 4. However, the total charge utilized during the treatment was also increased. The efficiency of PCOC degradation was observed to be higher when Mn²⁺ was used as the catalyst. The mineralization of aqueous solutions of PCOC, withdrawn from the reactor at certain time interval, has been followed by total organic carbon (TOC) decay and dechlorination. A fast and complete degradation of the aromatic ring was achieved in photoelectro-Fenton system. 41.7% TOC decay and complete dechlorination were observed by consuming only 141.4 C electrical charge during a 300 min photoelectron-Fenton treatment. In the case of electro-Fenton system, 280.7 C electrical charge was consumed during 450 min of electrolysis to attain a similar degradation of PCOC. 14.9% TOC removal and 89.3% dechlorination have been obtained in this system under the applied conditions.     

Tomato Seed Oil II Evaluation of the Egyptian Tomato Seed Oil and the Residual Meal

The oil extracted from tomato seeds and the resultant cake were evaluated. The whole seeds were analyzed for the gross composition. The oil extracted with hexane was examined for its physical and chemical properties. The residual meal was evaluated for the gross, minerals and amino acids. The obtained results were compared with those of cotton seeds.     

Consistency of randomized and finite sized decision tree ensembles

Regression via classification (RvC) is a method in which a regression problem is converted into a classification problem. A discretization process is used to covert continuous target value to classes. The discretized data can be used with classifiers as a classification problem. In this paper, we use a discretization method, Extreme Randomized Discretization, in which bin boundaries are created randomly to create ensembles. We present an ensemble method for RvC problems. We show theoretically for a set of problems that if the number of bins is three, the proposed ensembles for RvC perform better than RvC with the equal-width discretization method. We use these results to show that infinite-sized ensembles, consisting of finite-sized decision trees, created by a pure randomized method (split points are created randomly), are not consistent. We also theoretically show, using a set of regression problems, that the performance of these ensembles is dependent on the size of member decision trees.     

Preparation and characterization of carboxylic cation exchange resins from the reaction of poly(vinyl alcohol) with melamine-formaldehyde and some hydroxy acids

The synthesis of cation exchange resins via the reaction of poly(vinyl alcohol) as a carrier, citric acid as a catalyst and reactive additive to produce resin structures with grafted carboxy groups, along with a melamine-formaldehyde precondensate, responsible for crosslinking-reinforcing and insolubilizing the resin structure as well as for fixing and binding the acidic functional groups onto the resin structure, has been investigated using varied molar ratios of reactants and varied time as well as temperature. Reaction conditions were selected to prepare a cation exchange resin based on citric acid. Two other cation exchange resins based on tartaric acid and glycolic acid, were also prepared under the same selected reaction conditions. These three resins were characterized by potentiometric titration, water solubility and swellability, as well as durability to use.