bluuebunny/crossref_metadata_2025 huggingface dataset:
Antifreeze life cycle assessment, II: Mathematical modeling
Authors: Kesic Jelena , Skala Dejan
Published: March 2009

A mathematical model based on the mass and energy balances of all the processes included in antifreeze life cycle assessment (LCA) was defined in the first part of this study [1]. The part of energy that can be transformed into some other kind of energy is called exergy in all energy processes. The concept of exergy considers the quality of different types of energy and materials. It is also a connection between energy and mass transformations where the physical meaning of exergy loss is the loss of material and energy that must be used in the process. The results of the LCA calculation are very useful for analyzing the obtained products and used processes and for determining the conditions under which this analysis was conducted. The result of this study indicated that recycling is the most satisfactory solution for the treatment of used antifreeze taking into account two parameters: material and energy consumption. The reuse of antifreeze should not be neglected as a solution of this analysis.
Aldol condensation of the inferior aldehydes over dealuminated clinoptilolite
Authors: Cobzaru Claudia , Oprea Spiridon , Dumitriu Emil , Hulea Vasile
Published: March 2009

The catalytic performances of dealuminated clinoptilolite in the vapour-phase condensation of acetaldehyde and formaldehyde were investigated. The activity of dealuminated clinoptilolite in terms of the overall conversion of the acetaldehyde is comparable with that of the cation-exchanged forms (Na+, Ni2+, Fe3+). The dealumination process of clinoptilolite exhibits a favourable effect on the catalytic selectivity toward crotonaldehyde formation.
Influence of the hemp component in non-homogeneous yarns on the elastic behavior of knits made therefrom
Authors: Milosavljevic Svetlana , Tadic Tanja , Stankovic Snezana
Published: March 2009

One of the aims of producing non-homogeneous yarns is the improvement of their mechanical, aesthetic and comfort properties. In the case of hemp yarns, known by their predominantly technical uses, non-homogeneous yarns containing other chemical fiber yarn components besides hemp, could serve as a solution for making hemp textiles more acceptable for the production of clothing items. Different two-plied yarns, having always as one of the components 50 Tex hemp yarn, were exposed to axial stresses. Also their behavior after the relaxation of axial stress was studied in order to obtain an insight into the change of the elastic properties. Knitted fabrics of identical structure, made of these yarns, were exposed to compression and axial tests. The results obtained, correlated with the change of the relative cover of knits and to their structure (stitch density, surface mass, density, free open surface etc.) demonstrated the influence of the non-hemp components on the change of some basic properties of knits. These data could be important for the use and maintenance of hemp containing knitted clothing, as well as for their environmental acceptability.
Characterization of RuO2, Ru and Ru0.3Ti0.7O2 materials and their behaviour in hydrogen evolution reaction
Authors: Paseka Ivo
Published: March 2009

Polarization characteristics of the hydrogen evolution reaction were studied at RuO2 Ru0.3Ti0.7O2 and Ru electrodes prepared by various methods. The initial activity of all oxide electrodes, related to the real surface area, was comparable. After a long-term cathodic loading of electrodes the change of physical-chemical properties occurred. Voltametric curves of electrodes showed that ad- and absorption of hydrogen occurred after a long-term cathodic loading. Absorbed hydrogen caused changes of RuO2 lattice parameters and even changes of lattice parameters of the Ti support on which the RuO2 layer was deposited. Arisen stresses in the Ru - oxides layers caused the destruction of the electrode layer and limited life-time of these electrodes.
Inorganic coatings for the protection of marble surfaces from deterioration
Authors: Kanellopoulou Dimitra , Koutsoukos Petros
Published: March 2009

The dissolution of marble, a calcitic natural stone is an important cause contributing to the weathering process of the building materials of monuments, statues and other artefacts of cultural heritage. Protection against dissolution may be effected either through the use of water soluble additives or by the development of coatings of sparingly soluble salts of inhibitors of dissolution with calcium. In the present study coatings were prepared by the reaction of anions known to protect marble against dissolution: phosphate, phosphonate and oxalate anions were used in acidic media for the development of the respective calcium salts. The present study is a contribution both to understanding the presence of coatings found on ancient monuments and to the development of novel methods for the protection of calcitic materials. For the phosphoric acid treatment, the increase of the calcium concentration resulted in the re-precipitation of the calcium phosphate dehydrate phase forming coatings of 100 ?m converting to the less acidic octa-calcium phosphate. The efficiency towards dissolution was demonstrated with dissolution kinetic experiments at constant undersaturation, which showed partial dissolution of the calcium phosphate coating. The use of (1-hydroxyethylidene)- 1,1 diphosphonic acid (HEDP) both in solution and in the form of coatings also resulted in reduced rates of dissolution for Pentelic marble slabs. Two different calcium-diphosphonate salts were formed depending on the appliced pH. Finally, oxalic acid treatment resulted in the formation of a layer of calcium oxalate monohydrate. The independence of the solubility of this salt on pH makes it a good candidate for the protection of marble against dissolution in polluted environment.
Mathematical modeling of the ion exchange processes of sodium clinoptilolite with heavy metal ions from residual waters
Authors: Cobzaru Claudia , Oprea Spiridon
Published: March 2009

The ion-exchange capacity of volcanic tuff in the Na+ form (70% clinoptilolite content), used for removing heavy metals in residual waters, was investigated under different conditions (temperature, time and exchange solution concentration). These parameters are necessary and sufficient for the mathematical modeling of the ion-exchange process. The corresponding mathematical models show common characteristics due to the good arrangement of the experimental points on the response surfaces and correlation coefficients close to unity. Differences appear with respect to the shape of the response surface and model equations. .
In the frame of globalization, some tracks for the future of chemical and process engineering
Authors: Charpentier Jean-Claude
Published: March 2009

In today's economy, chemical engineering must respond to the changing needs of the chemical process industry in order to meet market demands. The evolution of chemical engineering is necessary to remain competitive in global trade. The ability of chemical engineering to cope with managing complex systems met in scientific and technological problems is addressed in this paper. Chemical Engineering is vital for sustainability: to satisfy both the market requirements for specific end-use properties of products and the social and environmental constraints of industrial-scale processes. An integrated system approach of complex multidisciplinary, non-linear non-equilibrium processes and phenomena occurring on different length and time scales is required. This will be obtained due to breakthroughs in molecular modeling, scientific instrumentation and related signal processing and powerful computational tools. The future of chemical engineering can be summarized by four main objectives: (1) Increase productivity and selectivity through intensification of intelligent operations and a multiscale approach to processes control; (2) Design novel equipment based on scientific principles and new production methods: process intensification using multifunctional reactors and microengineering and microtechnology (3) Extend chemical engineering methodology to product design and engineering using the "triplet 3PE molecular Processes-Product-Process Engineering" approach; (4) Implement multiscale application of computational chemical engineering modeling and simulation to real-life situations from the molecular scale to the production scale.
Synthesis of calcium aluminates through the polymeric precursor route
Authors: Gaki A. , Chrysafi R. , Perraki Th. , Kakali G.
Published: March 2009

The Pechini method is a polymeric precursor route for the synthesis of polycrystalline ceramics of high purity. The conventional solid state synthesis of calcium aluminate compounds requires long-term lasting sintering at high temperatures. In this study, the Pechini method was applied for the preparation of pure CaO.Al2O3 and 3CaO.Al2O3. Solid state synthesis was also used in order to compare the final products obtained by the two methods. The intermediate and final products obtained were characterized by XRD and FTIR spectroscopy. It was concluded that the Pechini method can be successfully applied for the preparation of high purity CaO.Al2O3 and 3CaO.Al2O3. The formation of 3CaO.Al2O3 and CaO.Al2O3 requires three-hour sintering at 1000?C and 900?C, respectively. The main intermediate product was 5CaO.3Al2O3 in the case of 3CaO.Al2O3, while in the case of CaO.Al2O3 there were no other crystalline intermediate products. The samples prepared through solid state synthesis, contain a considerable amount of secondary phases, even after sintering at 1350-1400?C for more than 15 hours.
Enzyme-catalyzed reactions in different types of high-pressure enzymatic reactors
Authors: Primozic Mateja , Habulin Maja , Paljevac Muzafera , Knez Zeljko
Published: March 2009

The enzyme-catalyzed hydrolysis of carboxy-methyl cellulose (CMC) was performed in three different types of reactors; in a batch stirred-tank reactor (BSTR) operating at atmospheric pressure, in a high-pressure batch stirred-tank reactor (HP BSTR) and in a high-pressure continuous tubular-membrane reactor (HP CTMR). In the high-pressure reactors aqueous SC CO2 was used as the reaction medium. The aim of our research was optimization of the reaction parameters for reaction performance. All the reactions were catalyzed by cellulase from Humicola insolens. Glucose production in the high-pressure batch stirred-tank reactor was faster than in the BSTR at atmospheric pressure. The optimal temperature for the reaction performed in the BSTR at atmospheric pressure was 30?C, while the optimal temperature for the reaction performed in SC CO2 was 32?C. The influence of the application of tubular ceramic membranes in the high-pressure reaction system was studied on the model reaction of CMC hydrolysis at atmospheric pressure and in SC CO2. The reaction was catalyzed by cellulase from Humicola insolens covalently linked to the surface of the ceramic membrane. The hydrolysis of CMC in SC CO2 and at atmospheric pressure was performed for a long time period. The reaction carried out in SC CO2 was more productive than the reaction performed at atmospheric pressure.
Lipase-catalyzed esterification in a reversed micellar reaction system
Authors: Tonova K. , Lazarova Z. , Nemestothy N. , Gubicza L. , Belafi-Bako K.
Published: March 2009

In this work, the lipase-catalyzed synthesis of i-amyl oleate was performed in a reversed micellar system of a cationic surfactant, CPC. The influence of the RM-system constituents on the biocatalysis characteristics (initial esterification rate and conversion extent) was studied and discussed in terms of the RM-structure. The initial water content in the RM-system (the water to surfactant mole ratio, Wo), affected both reaction parameters in a bell-shaped manner, with the maximum depending on the alcohol amount. In general the optimal Wo-values remained between 34 ?40 for a wide range of the initial substrate ratio. The polarity (logP) and the structure of the organic solvent used as the RM-continuum strongly affected the kinetic parameters. A linear function of the initial rate on arg(logP) was established for the alkanes up to n-C1O. The highest rates were measured using a medium of cycle or branched alkanes. The esterification under inhibiting concentrations of the substrates could be intensified by a small change in the initial Wo, thus improving the enzyme RM-accommodation and manipulating the effective concentrations of both substrates around the lipase. In the studied RM-system of 0.115 mol dm-3 CPC, the maximal initial rate of the lipase-catalyzed i-amyl oleate synthesis was found to be limited at ~340 ?mol min-1 g-1.
Optimization of the mixing in stirred bioreactors, 1. Comparative analysis of the mixing efficiency with different radial impellers for simulated broths
Authors: Cascaval Dan , Galaction Anca-Irina , Folescu Elena
Published: March 2009

Although radial impellers, especially the Rushton turbine, are widely used in stirred bioreactors, their applicability is limited by the high apparent viscosities of the broth. Beside the intensification of broth circulation, the energetic efficiency and the shear effects on biocatalysts must be taken into account to select the optimum impeller or impellers combination. In this context, the paper presents a comparative study on the efficiency of seven different radial impellers for simulated broth mixing in a stirred bioreactor. The analysis was made by means of the mixing time values obtained by vertically changing the position of the pH-sensor in the broths, in correlation with the energy consumption needed for a certain level of mixing time or for the uniform distribution of the mixing intensity into the bulk volume of the broths.
Ozone absorption in raw waters
Authors: Takic Ljiljana , Veljkovic Vlada , Pejanovic Srdjan
Published: March 2009

The ozone absorption in raw water entering the main ozonization step at the Belgrade drinking water supply plant was investigated in a continuous stirred tank reactor (CSTR). A slow chemical reaction rate of dissolved ozone and pollutants present in raw water have been experimentally determined. The modified Hatta number was defined and calculated as a criterion which determines whether and to which extent the reactions of ozone and pollutants influence the rate of the pure physical ozone absorption.
Engineered tissue grafts: A new class of biomaterials for medical use
Authors: Vunjak-Novakovic Gordana
Published: March 2009

Recent advances in the stem cell biology, the biomaterials science, and the design of the tissue culture bioreactors, help us address the growing need to find replacements for lost and worn-out human tissues and organs in an entirely new way. Biological equivalents of native tissues are grown in a laboratory using tissue engineering techniques and investigated for their functionality, both in vitro and in animal models. We briefly review the key principles for engineering these advanced, native-like biomaterials capable to take over the lost function of our tissues. We also provide an example of the state of the art approach to the tissue engineering.
The interlaminar strength of the glass fiber polyester composite
Authors: Putic Slavisa , Bajceta Branislav , Vitkovic Dragana , Stamenovic Marina , Pavicevic Vladimir
Published: March 2009

The paper outlines the method and the results of the experimental investigation of interlaminar strength of glass fibre reinforced polyester composites, with the aim of determining the influence that the structure, a reinforcement type and a sort of resin exert upon the interlaminar strength. The tested specimens were fabricated under different formation conditions, namely in eight composition patterns and with three sorts of resin used for polymerization.
Comparison of real development levels of countries: Genesis and perspectives
Authors: Prekajac Zora
Published: March 2009

Comparison of levels of development among countries is usually done by reducing values in national currencies with a common denominator, using the official exchange rate. Because of its unreality, the values calculated in this way do not illustrate real relations between compared countries. That brings about the launching of the UN International Comparison Project (latter Programme) with two fold aims: developing a method for international comparison of real domestic product which could be applied to a number of very heterogeneous countries, and the comparison of growing number of very different countries. Until now six phases of comparisons are finished. Taking into consideration problems that appeared in the realization of the VI ICP phase as well as quality improvement proposals, a decision has been made to launch a new, global round for 2003-2006. Comparison will cover 150 countries (the widest coverage ever). This will give global character to the comparison, which was the end cause of the ICP.
Bureaucratic behavior: A review of the theory and its application to Serbian public administration
Authors: Zarkovic-Rakic Jelena
Published: March 2009

A professional and competent public administration is necessary for successful transition from a socialist, centrally planned economy to a functioning market democracy. The difficulty lies in building an organized and effective civil service sector. This paper gives a brief overview of formal bureaucratic reasoning, beginning with Niskanen?s theory, followed by the principal-agent model. The "Weberian state hypothesis", which provides an alternative view of bureaucracies in less developed countries, is subsequently explored. Finally, the currant state of Serbian public administration is described, along with a discussion of challenges to be addressed in the future.
Investigation on the Occurrence of Ochratoxin A in Maize in Bangladesh
Authors: Dawlatana M , Shahida S , Rahim Matiur , Hassan M Tariqul
Published: March 2009

Maize was collected from different markets of Bangladesh for the determination of ochratoxin A. Simultaneously controlled maize samples were analyzed to assess the ochratoxin A level of market samples and that of controlled samples. A total of 120 samples were analyzed to determine ochratoxin A including 70 market samples and 50 controlled samples. Market samples were found containing a high contamination level of ochratoxin A ranged from 1 to 117 Î¼g/kg and incidence rate was 40% whereas in the controlled samples the contamination rate was found very low ranged from 3 to 9 Î¼g/kg and the incidence rate was found 10% only. Key words: Maize, Ochratoxin A, Occurrence, Bangladesh, HPTLC Â  doi: 10.3329/bjsir.v43i4.2239 Bangladesh J. Sci. Ind. Res. 43(4), 495-500, 2008
Synthesis of Luminescent ZrO2:Eu3+ Nanoparticles and Their Holographic Sub‐Micrometer Patterning in Polymer Composites
Authors: Ninjbadgar Tsedev , Garnweitner Georg , Börger Alexander , Goldenberg Leonid M. , Sakhno Oksana V. , Stumpe Joachim
Published: March 2009

Here, the facile synthesis of fluorescent ZrO2:Eu3+ nanoparticles with luminescence quantum yield of up to 8.7% that can be easily dispersed in organic solvents and utilized for the preparation of organic/inorganic volume holographic gratings is presented. The nanoparticles are prepared through a one‐step solvothermal process resulting in spherical particles with a mean size of 4 nm that were highly crystalline directly after the synthesis, without any need for calcination treatment. Detailed luminescence studies of the nanoparticles as a function of Eu3+ content demonstrate that the dopant concentration and its site symmetry play an important role in the emissive properties and lifetime of the luminescent centers. It is shown that the luminescence quantum yield of the colloidal ZrO2:Eu3+ nanoparticles increases with dopant concentration up to a critical concentration of 11 mol% while the luminescence lifetime is shortened from 1.8 to 1.4 ms. Holographic photopolymerization of suitable monomer mixtures containing the luminescent nanoparticles demonstrated the ability to inscribe volume Bragg gratings (refractive index contrast n1 up to 0.011) with light‐emissive properties, evidencing the high suitability of this approach for the fabrication of tailored nanomaterials for elaborate and demanding applications.
COL4A1 mutation in two preterm siblings with antenatal onset of parenchymal hemorrhage
Authors: de Vries Linda S. , Koopman Corine , Groenendaal Floris , Van Schooneveld Mary , Verheijen Frans W. , Verbeek Elly , Witkamp Theo D. , van der Worp H. Bart , Mancini Grazia
Published: March 2009

Objective

To report the presence of intracerebral hemorrhage and porencephaly, both present at birth, in two preterm infants with a mutation in the collagen 4 A1 gene.

Methods

Two preterm infants with antenatal intracerebral hemorrhage and established porencephaly, as well as their affected mother and grandfather, underwent neurological and ophthalmological examination and magnetic resonance imaging of the brain. Mutation analysis of the COL4A1 gene was performed in the infants and in their mother.

Results

Both infants had a novel G1580R mutation in the COL4A1 gene, encoding procollagen type IV α1. A history of mild antenatal trauma was present in the first but not in the second infant. Both preterm infants were asymptomatic at birth. The intracerebral hemorrhage and porencephaly were diagnosed with cranial ultrasound examination and were subsequently confirmed with magnetic resonance imaging. Leukoencephalopathy was present in the mother and in her father.

Interpretation

Mutation of the COL4A1 gene appears to be a risk factor of antenatal intracerebral hemorrhage followed by porencephaly in the preterm newborn. Ann Neurol 2009;65:12–18
Alzheimer's Disease: From Pathology to Therapeutic Approaches
Authors: Jakob‐Roetne Roland , Jacobsen Helmut
Published: March 2009

Mind how you go: The current strategies for the development of therapies for Alzheimer's disease are very diverse. Particular attention is given to the search for inhibitors (see picture for two examples) of the proteolytic enzyme β‐ and γ‐secretase, which inhibits the cleavage of the amyloid precursor proteins into amyloid β peptides, from which the disease‐defining deposits of plaque in the brains of Alzheimer's patients originates.

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Research on senile dementia and Alzheimer's disease covers an extremely broad range of scientific activities. At the recent international meeting of the Alzheimer's Association (ICAD 2008, Chicago) more than 2200 individual scientific contributions were presented. The aim of this Review is to give an overview of the field and to outline its main areas, starting from behavioral abnormalities and visible pathological findings and then focusing on the molecular details of the pathology. The “amyloid hypothesis” of Alzheimer's disease is given particular attention, since the majority of the ongoing therapeutic approaches are based on its theoretical framework.
Functionalization of ethylene–propylene–diene monomer rubber with maleic anhydride in the melt state through high‐shear stress‐induced initiation
Authors: Zhang Ling , Zhang Yuncan , Yao Huqing
Published: March 2009

The functionalization reactions of ethylene–propylene–diene monomer rubber (EPDM) with maleic anhydride (MAH) in melt state through high‐shear‐stress‐induced initiation by an increase in the screw rotation speed of the twin‐screw extruder and through compounded initiation by the addition of some initiator and an increase in the screw rotation speed were investigated. The results show that, with increasing screw rotation speed and reaction temperature, the percentage grafting and melt flow rate of the functionalized products (EPDM‐g‐MAH) were noticeably increased, and the viscosity‐average molecular weight decreased, which implied that the grafting reaction consisted of the chain scission and grafting reaction of the produced macroradicals with MAH. In the presence of a certain peroxide initiator, the crosslinking reaction during melt extrusion was suppressed by an increase in the screw rotation speed. The percentage grafting of EPDM‐g‐MAH amounted to 1.1%, its melt flow rate was between 0.3 and 4.0 g/10 min, and its gel content was less than 1.0%, depending on the screw rotation speed and reaction temperature. Impact testing and scanning electron microscopy showed that the functionalized product prepared through the high shear stress‐induced initiation had a higher blocking activity with the amide terminated of PA66 than that prepared through the peroxide initiation or through the compound initiation, and the impact strength of the PA66/EPDM blends, improved by the high‐shear‐stress‐induced product was noticeably higher than those of the peroxide‐initiated product or the compound‐initiated one. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis, characterization, and anticorrosive coating properties of waterborne interpenetrating polymer network based on epoxy‐acrylic‐oleic acid with butylated melamine formaldehyde
Authors: Zafar Sarvat , Zafar Fahmina , Riaz Ufana , Ahmad Sharif
Published: March 2009

The present study reports the synthesis and characterization of waterborne interpenetrating network (IPN) of epoxy‐acrylic‐oleic acid (EpAcO) with butylated melamine formaldehyde (BMF). The effect of BMF on the formation of IPN was investigated in terms of physicochemical, spectral, morphological, and thermal analyses. The coating properties of the IPN were investigated for their physicomechanical, corrosion resistance, and antimicrobial activity. The formation of the IPN was confirmed by FTIR and 1H NMR analyses as well as physicochemical properties. The EpAcO‐BMF IPN coatings were found to exhibit far superior corrosion resistance performance and good thermal stability when compared with the reported waterborne epoxy acrylic‐melamine formaldehyde systems [EpAc‐MF]. The preliminary antimicrobial investigations of the IPNs were carried out by agar diffusion method against some bacteria and fungi. The results revealed that antimicrobial activities were enhanced upon the formation of IPN. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and antimicrobial activity of metronidazole containing polymer and copolymers
Authors: Kenawy El‐Refaie , Al‐Deyab Salem S. , Omar Shaker Nihal , El‐Sadek Baheya Mohamed , Khattab Abeer H. B.
Published: March 2009

Homopolymer and copolymers containing metronidazole (MTZ) drug were synthesized. Acryloyl chloride was reacted with MTZ (drug) to produce monomer containing MTZ, and then the monomer was copolymerized with various amounts of methyl methacrylate. The produced monomer, homopolymer, and copolymers were characterized by elemental analysis, IR, and 1H‐NMR. The antimicrobial activities of the synthesized polymers were tested against Kelpsilic as fungal organisms, and Escherichia coli, Bacillus subitilus, and Pesudomonus areuginosa as bacteria organisms. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
UV–VIS absorption and NIR‐stimulated emission of Nd3+: PVA films
Authors: Adiyodi Amrutha K. , Jyothy P. V. , Unnikrishnan N. V.
Published: March 2009

Neodymium‐doped polyvinyl alcohol films were prepared and the optical properties of the films were investigated. By applying Judd–Ofelt theory, the Ω parameters were obtained from the absorption spectrum. Various radiative parameters like transition probability for each level (AJ), total transition probability (AT), branching ratio (βR), radiative lifetime (τrad), and absorption cross‐section (σA) were calculated. The theoretically obtained branching ratio and integrated absorption cross‐section are found to be greater for the transition 4F3/2 → 4I11/2. From the emission spectrum peaked at 1064‐nm stimulated emission cross‐section (σE), the line width (Δλeff) is calculated to be 6.21 × 10−21 cm2 and 41 nm, respectively. Further the variation of the optical gain with the length of the film was studied and the slope efficiency (η = 8.5%) was determined from laser measurements. These results clearly support the potentiality of the Nd3+: polyvinyl alcohol films in realizing optical amplification and stimulated emission. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Crystallization behavior of “wet brush” and “dry brush” blends of PS‐b‐PEO‐b‐PS/h‐PEO
Authors: Luo Chunyan , Han Xia , Gao Ying , Liu Honglai , Hu Ying
Published: March 2009

The crystallization behavior of the blending system consists of homopolymer poly(ethylene oxide) (h‐PEO) with different molecular weights, and polystyrene‐block‐poly (ethylene oxide)‐block‐polystyrene (PS‐b‐PEO‐b‐PS) triblock copolymer has been investigated by DSC measurements. The crystallization of PEO block (b‐PEO) in block copolymer occurs under much lower temperature than that of the h‐PEO in the bulk (ΔT > 65 °C), which is attributed to the homogeneous nucleation crystallization behavior of the b‐PEO microdomains. In both the “dry‐brush” and the “wet brush” blending systems, the homogeneous nucleation crystallization temperature of PS‐b‐PEO‐b‐PS/h‐PEO blends increases due to the increase of the domain size. The heterogeneous nucleation crystallization temperatures of h‐PEO in the wet brush blending systems are higher than that of the corresponding h‐PEO in the bulk. At the same time, the heterogeneous nucleation crystallization temperature of b‐PEO10000 decreases from 43°C to 30°C and 40°C in the h‐PEO600 and h‐PEO2000 blending systems, respectively, because of the stretching of the PEO chains in the wet brush. However, this kind of phenomenon does not happen in the dry brush blending systems. The self‐seeding procedure was used to further ascertain the nucleation mechanism in the crystallization process. As a result, the self‐seeding domains have been confirmed, and the difference between the dry brush and wet brush systems has been observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of EMAA compatibilizer on the structure and properties of HDPE/hydrotalcite nanocomposites prepared by melt mixing
Authors: Ardanuy M. , Velasco J. I. , Maspoch M. L. , Haurie L. , Fernández A. I.
Published: March 2009

High‐density polyethylene (HDPE)/hydrotalcite nanocomposites were prepared and characterized with a partially neutralized sodium ionomer of poly(ethylene‐co‐methacrylic acid) (EMAA) as a compatibilizer. Moreover, nanocomposites based on this ionomer were characterized as patterns to analyze the interactions between the hydrotalcite sheets and the methacrylic groups on the ionomer. Hydrotalcite particles were organically modified with sodium dodecyl sulfate ions. Their presence in the interlayer space was confirmed by means of Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). Morphological analysis carried out with XRD and transmission electron microscopy (TEM) revealed the partially exfoliated/intercalated structure achieved in the nanocomposites. The mechanical properties of the HDPE nanocomposites mainly depended on the nature of the polymer matrix. Higher values of the tensile strength and Young's modulus were found in the EMAA nanocomposites. Thermogravimetric analysis (TGA) showed that hydrotalcite particles improved the thermal stability and delayed the onset decomposition temperature of both HDPE and EMAA nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Magnesium/Copper Nanocomposite through Digestive Ripening
Authors: Kalidindi Suresh Babu , Jagirdar Balaji R.
Published: March 2009

Composing nanocomposites: Co‐digestive ripening of as‐prepared Mg and Cu colloids prepared by the solvated metal atom dispersion method results in a highly monodisperse colloid of Mg/Cu nanocomposite with an average particle size of 3.0±0.5 nm. Annealing of these samples at 300 °C gives the Cu/MgO nanocomposite.

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Bioassembly of three‐dimensional embryonic stem cell‐scaffold complexes using compressed gases
Authors: Xie Yubing , Yang Yong , Kang Xihai , Li Ruth , Volakis Leonithas I. , Zhang Xulang , Lee L. James , Kniss Douglas A.
Published: March 2009

Tissues are composed of multiple cell types in a well‐organized three‐dimensional (3D) microenvironment. To faithfully mimic the tissue in vivo, tissue‐engineered constructs should have well‐defined 3D chemical and spatial control over cell behavior to recapitulate developmental processes in tissue‐ and organ‐specific differentiation and morphogenesis. It is a challenge to build a 3D complex from two‐dimensional (2D) patterned structures with the presence of cells. In this study, embryonic stem (ES) cells grown on polymeric scaffolds with well‐defined microstructure were constructed into a multilayer cell‐scaffold complex using low pressure carbon dioxide (CO2) and nitrogen (N2). The mouse ES cells in the assembled constructs were viable, retained the ES cell‐specific gene expression of Oct‐4, and maintained the formation of embryoid bodies (EBs). In particular, cell viability was increased from 80% to 90% when CO2 was replaced with N2. The compressed gas‐assisted bioassembly of stem cell‐polymer constructs opens up a new avenue for tissue engineering and cell therapy. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Simultaneous extraction and concentration of penicillin G by hollow fiber renewal liquid membrane
Authors: Ren Zhongqi , Zhang Weidong , Lv Yuanyuan , Li Jing
Published: March 2009

In this article, hollow fiber renewal liquid membrane (HFRLM) technique was used for recovery of penicillin G from aqueous solution. The organic solution of 7 vol % di‐n‐octylamine (DOA) + 30 vol % iso‐octanol + kerosene was used as liquid membrane phase, and Na2CO3 aqueous solution was used as stripping phase. Experiments were performed as a function of carrier concentration in the organic phase, organic/aqueous volume ratio, pH, and initial penicillin G concentration in the feed phase, pH in the stripping phase, flow rates, etc. The results showed that the HFRLM process was stable and could carry out simultaneous extraction and concentration of penicillin G from aqueous solutions. As a carrier facilitated transport process, the addition of DOA in organic phase could greatly enhance the mass transfer rate; and there was a favorable organic/aqueous volume ratio of 1:20 to 1:30 for this system. The mass transfer flux and overall mass transfer coefficient increased with decreasing pH in the feed phase and increasing pH in the stripping phase, because of variation of the mass transfer driving force caused by pH gradient and distribution equilibrium. The flow rate of the shell side had significant influence on the mass transfer performance, whereas the effect of flow rate of lumen side on the mass transfer performance was slight because of the mass transfer intensification of renewal effect in the lumen side. The results indicated that the HFRLM process was a promising method for the recovery of penicillin G from aqueous solutions. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Sustaining changes that support student success in community college
Authors: Burdman Pamela
Published: March 2009

This chapter explores various theories of change for community colleges and examines how external agencies and funders have sought to support reforms that improve success for diverse groups of students. The author provides a preliminary scan of how successful institutionalization attempts have been, including national and regional examples, and suggests ways that community colleges can sustain reforms over time.
Anatomy of the patent foramen ovale for the interventionalist
Authors: McKenzie Jeff A. , Edwards William D. , Hagler Donald J.
Published: March 2009

Background: Patent foramen ovale (PFO) is an interatrial communication whose management is controversial. Several manufacturers have submitted protocols for Food and Drug Administration (FDA) approval of their PFO closure device. The purpose of this study was to define anatomy relevant to percutaneous PFO closure, validate the clinical observation that most PFOs contain little tissue rim at the aorta, comment on proposed closure guidelines, and to discuss approaches to PFO closure. Methods: From the Mayo Clinic Tissue Registry, five normal hearts with PFO were selected from each sex from the first 10 decades of life (n = 100). Measurements (mm) included PFO length, diameter, and distance from FO‐superior vena cava (SVC) and FO‐aortic annulus (AoAn). Patient age, weight, and height were obtained from autopsy reports, and body surface area (BSA) was calculated. Results: PFO length and diameter increased with age (P = 0.029 and 0.001, respectively), and FO‐SVC and FO‐AoAn increased with BSA (P ≤ 0.0001 and 0.006, respectively). PFO diameter was larger in women than men (P = 0.028). Using current sizing guidelines, 66% (CI = 56–75%) of the 100patients would have been excluded from device closure, and only 31% could have received the smallest (18 mm) device. Conclusions: Our results suggest that the proposed device closure guidelines may result in inappropriate device sizing. In addition to excluding suitable candidates, strict application of the guidelines could also result in incomplete closure or device embolization. Suggestions for modification of the guidelines and options for device closure are discussed. © 2009 Wiley‐Liss, Inc.
Reactions between germanium and platinum in sub/supercritical water
Authors: Nishikawa E. , Wakao N.
Published: March 2009

Reactions between platinum and germanium in sub/supercritical water were carried out by exposing a platinum plate to an aqueous solution at 20‐40 MPa and 553‐713 K. The surface of the platinum plate was found to be covered with a film of fine crystals of platinum‐germanium compounds, Pt3Ge, Pt3Ge2, Pt2Ge and PtGe, depending upon the pressures and temperatures of the environment.
A study of supported molybdenum catalysts for the reduction of SO2 with CH4: Effect of sulphidation method
Authors: Mulligan David J. , Tam Kawai , Berk Dimitrios
Published: March 2009

An experimental investigation of the effect of sulphidation method of supported molybdenum catalysts used in the reduction of SO2 with Ch4 was carried out. Two sulphidation methods, one using H2S and the other using a mixture of SO2/CH4, are compared. The methods are evalauted with respect to molybdenum retention, extent of molybdenum sulphidation, and catalytic activity. Mo/Al2O3 catalysts sulphided with H2S are superior to those sulphided under SO2 and CH4 reaction conditions. Although complete sulphidation is never achieved in either of the two cases, the higher activity found with H2S‐sulphided catalysts is attributed to a higher degree of molybdenum sulphidation resulting in a higher MoS2 content. The 15% Mo/Al2O3 catalyst sulphided with H2S at 600°C showed the highest activity and had the highest MoS2 content.
Time optimal control of high dimensional systems by iterative dynamic programming
Authors: Bojkov Bojan , Luus Rein
Published: March 2009

For time optimal control, the problem is first transformed into a finite dimensional optimization problem by using time stages of varying lengths to enable accurate switching, and then solved by iterative dynamic programming. In high dimensional systems care is necessary to ensure convergence to the global optimum. Incorporating penalty functions into the performance index and using an adequate number of stages can yield the global optimum. The use of a continuation approach, where the number of stages in an intermediate solution is systematically increased, appears to be more effective. Three linear systems are used to develop and to test the approaches.
Factors affecting the optimal performance of a high‐yield pulping operation
Authors: Broderick G. , Paris J. , Valade J. L.
Published: March 2009

Process models based on data from close to one hundred pilot scale pulping runs are used to investigate strategies for operating a chemimechanical pulp mill. Optimal values for a total of 55 process and pulp quality variables have been calculated by applying a genetic algorithm search to a fuzzy model of the overall system. This model consists of over 90 distinct empirical relationships. Results indicate that pulp quality is maintained at minimal fibre and energy costs when the chemical pretreatment is conducted at moderately low temperature using a high SO2 concentration producing both high sulphonation and high yield simultaneously. Subsequent refining should involve applying at least 65% of the total energy in the primary stage. The pulp quality obtained is comparable to that of a CTMP pulp but with the added benefit of higher freeness.
Pyrolysis of kraft lignin in molten ZNCL2‐KCL media with tetralin vapor addition
Authors: Kudsy M. , Kumazawa H. , Sada E.
Published: March 2009

Kraft lignin was pyrolyzed in molten salt media of ZnCl2‐KCl mixture with tetralin vapor added in 0.4 and 4 mol% diluted with N2 in the temperature range of 400 to 700°C. The gas chromatographic analyses of pyrolysis products revealed that the yield of H2 was not increased by tetralin vapor addition. This fact implies that the hydrogen radical produced from tetralin is consumed in the formation of phenolic compounds and light liquids but not in the formation of H2. p‐Cresol was the most abundant phenolic compound. The yield of total phenolic compounds with 4 mol% tetralin vapor added was increased by ca. 80% as compared to that in neat pyrolysis of Kraft lignin.
Catalytic conversion of canola oil to fuels and chemicals over various cracking catalysts
Authors: Katikaneni Sai P. R. , Adjaye John D. , Bakhshi Narendra N.
Published: March 2009

The catalytic conversion of canola oil to fuels and chemicals was studied over HZSM‐5, H‐mordenite, H‐Y, silicalite, aluminum‐pillared clay (AL‐PILC) and silica‐alumina catalysts in a fixed bed micro‐reactor. The reactor was operated at atmospheric pressure, a temperature range of 375−500°C and weight hourly space velocity (WHSV) of 1.8 and 3.6 h−1. An organic liquid product (OLP), light hydrocarbon gases and water were the major products. The objective was to maximize the amount of OLP and its hydrocarbon content as well as optimize the selectivity for gas phase olefinic hydrocarbons. In addition, the performance of each catalyst in terms of minimizing the coke formation was examined. Among the six catalysts, HZSM‐5 gave the highest amount of OLP of 63 mass% at 1.8 WHSV and 400°C. The hydrocarbon content of this OLP product was 83.8 mass%. With the exception of silica‐alumina and aluminum‐pillared clay catalysts, the other catalysts gave high concentrations of aromatic hydrocarbons which ranged between 23.1–95.6 mass% of OLP. The gas products consisted mostly C3 and C4 hydrocarbons. Ethylene, propylene and butanes were some of the valuable hydrocarbon gases. The olefin/paraffin ratio of the gas products was highest for AL‐PILC catalysts but it never exceeded unity. The results showed that it was possible to significantly alter the yield and selectivity for the different hydrocarbon products by using different catalysts or changing the catalyst functionality such as acidity, pore size and crystallinity. Reaction pathways based on these results are proposed for the conversion of canola oil
A simplified model of nitric oxide emission from a circulating fluidized bed combustor
Authors: Talukdar J. , Basu P.
Published: March 2009

A simplified mathematical model leading to a closed form of solution is developed for estimation of nitric oxide emission from a coal fired circulating fluidized bed (CFB) furnace. The furnace is divided into two sections: a lower section below and an upper section above the secondary air injection level. Reactions in the cyclone and the return leg are neglected. Furnace dimensions, coal feed rate, coal composition and furnace temperature are inputs to the model which was validated against several pilot scale and commercial units. Experimental results from two pilot plants and two commercial power plants agree with model predictions. A sensitivity analysis was carried out using the model to examine the effect of different operating parameters and coal properties on the overall NO emission from the furnace. It was found that excess air and furnace temperature are most important factors influencing the NO emission level. The primary to secondary air ratio influences the NO emission level reasonably. Properties of coal are other factors which affect the NO emission to a large extent. The model, though it invovles some simplification, predicts the overall emission of NO with a level of accuracy accepted in commercial operation.
Propagation of a nonionic surfactant in radial sandstone cores
Authors: Kwok W. , Hayes R. E. , Nasr‐El‐Din H. A.
Published: March 2009

The dynamic adsorption of a nonionic surfactant, Triton X‐100®, on Berea sandstone with radial flow under a variety of injection rates, salinities and pH is examined. Mathematical modelling of the experimental data shows that the most consistent results are obtained using a kinetic hemimicelle model. The aggregation number (hemimicelle size) is independent of flow rate and salinity, but increases with increasing pH. In all cases, the aggregation number is lower under dynamic conditions than under static conditions, which is attributed to the shear force at the surface. The rate constants for adsorption increase with increasing flow rate, which is attributed to a decrease in mass transfer resistance.
A model for simultaneous measurement of gas and solid holdups in a bubble column using ultrasonic method
Authors: Warsito  , Uchida S. , Maezawa A. , Okamura S.
Published: March 2009

The ultrasonic method developed to measure the dispersed phase holdups in dispersion systems is based on the fact that the velocity of ultrasound in the dispersion is different from that in the liquid. The relationships between velocity differences in the term of transmission time differences of ultrasound and gas holdup in a gas‐liquid system and solid holdup in a liquid‐solid system were derived. The holdups became linearly dependent on the time differences, which is in agreement with the experimental data. Based on those relations, a model for simultaneous measurement of gas and solid holdups in three‐phase systems is proposed. The model permits measurement of the dispersed phase holdups by measuring the transmission time of ultrasound transmitted through the dispersions in two frequencies. It allows investigation of local holdups distributions in a bubble column and in a suspended bubble column.
A model for two‐phase turbulent mixing in a jet bubble column
Authors: Mitra‐Majumdar D. , Farouk B. , Shah Y. T. , Wisecarver K.
Published: March 2009

Mixing behavior of the two phase air‐water turbulent flow in a jet bubble column is examined. The time evolution of the mixing behavior of a liquid tracer in a turbulent air‐water flow within a jet bubble column is predicted using a model based on the fundamental governing equations of fluid motion. The predictions of the model are compared with experimental measurements. Measured residence time distributions (RTD) of the liquid tracer within the cone agree well with the predicted values given by the model. For the range of parameters considered in the study, lack of radial mixing and large axial mixing are evident within the cone of the jet bubble column. Use of fundamental mathematical models for the study of hydrodynamics in a two‐phase conventional bubble column has been reported earlier (Torvik, 1990; Jakobsen et al., 1993). The present paper extends the use of such models to predict the mixing characteristics in a jet bubble column.
Salt effect of CACL2, NH4i and NAI on vapor‐liquid equilibrium of ethanol + water system at 298.15 K
Authors: Yamamoto Hideki , Terano Tamotsu , Yanagisawa Masahiko , Tokunaga Junji
Published: March 2009

Salt effect on vapor‐liquid equilibrium for the ethanol + waiter system was measured at 298.15 K using an experimental apparatus based on the static method. The salting‐out effect of CaCl2, NH4I and NaI on the ethanol + water system follows the order of CaCl2 > NaI > NH4I. The observed experimental data were correlated by the use of a semi‐empirical model proposed by Hála (1983) with an accuracy of ± 2.13%. The application of Hála's model was confirmed in the ethanol + water system to be added the salts other than CaCl2 at 298.15 K.