bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of an Automated Pressure Ulcer Risk Assessment Model
Authors: Borlawsky Tara , Hripcsak George
Published: July 2007

The key to timely interventions and reducing avoidable incidence is the early identification of patients at risk for developing pressure ulcers. To enable the automatic detection of such patients and inform acute care interdisciplinary providers, a filter feature model using heuristic statistical methods was applied to a relational database of retrospective patient data including demographics, medications, and clinical visit details. These attributes served as input for the C4.5 decision tree induction algorithm, which was used to classify patient risk. The validity of the resulting classification model, Electronic Pressure Ulcer Prediction (ePUP), was assessed using a fourfold cross-validation. The current results show a limited application of such a naïve classification algorithm for automating pressure ulcer risk assessments. Additional refinements will be necessary before the predictions of ePUP are sufficient for general clinical use and the improvement of patient safety in acute care settings, and during the transition from hospital to home.
Polymorphism and epitope sharing between the alleles of merozoite surface protein-1 of Plasmodium falciparum among Indian isolates
Authors: Mamillapalli Anitha , Sunil Sujatha , Diwan Suraksha S , Sharma Surya K , Tyagi Prajesh K , Adak Tridibes , Joshi Hema , Malhotra Pawan
Published: July 2007

Background

The C-terminal region of merozoite surface protein-1 (MSP-1) is one of the leading candidates for vaccination against the erythrocytic stages of malaria. However, a major concern in the development of MSP-1 based malaria vaccine is the polymorphism observed in different geographicalPlasmodium falciparumisolates. To explore whether the sequence heterogeneity of PfMSP-1 leads to variation in naturally acquired anti-MSP-119antibodies, the present study was undertaken to study PfMSP-119sequence polymorphism in malaria-endemic villages in eastern India and also carried out a competition enzyme-linked immunosorbent assay using three PfMSP-119variant forms.

Methods

The sequence variations in the C-terminal region of PfMSP-119were determined in a malaria endemic region. Three PfMSP-119variants were produced inEscherichia coli(PfMSP119QKNG-L, PfMSP119EKNG-L and PfMSP119ETSR-F) and an immunodepletion assay was carried out using the corresponding patients' sera.

Results

Results revealed predominance of PfMAD20 allele among Indian field isolates. Seven PfMSP-119variant forms were isolated in a singe geographical location. Three of PfMSP-119variant forms when expressed inE. colishowed presence of cross-reaction as well as variant specific antibodies in malaria infected patient sera.

Conclusion

The present study demonstrates the existence of allele specific antibodies inP. falciparum-infected patient sera, however their role in protection requires further investigation. These results thereby, suggest the importance of a multi-allelic PfMSP-119based vaccine for an effective malaria control.
Involvement of Apolipoprotein A-IV and Cholecystokinin1 Receptors in Exogenous Peptide YY3–36-Induced Stimulation of Intestinal Feedback
Authors: Whited K. L. , Tso P. , Raybould H. E.
Published: July 2007

Peptide YY (PYY)3–36, released by intestinal lipid elicits functional effects that comprise the intestinal feedback response to luminal nutrients, but the pathway of action is not fully characterized. The aim of the present study was to determine the role of the apolipoprotein (apo) A-IV-cholecystokinin (CCK)1 receptor (CCK1R) pathway in exogenous PYY3–36-induced activation of the gut-brain axis and inhibition of gastric emptying and food intake. PYY3–36 (5 μg/100 g ip) significantly inhibited gastric emptying of a chow meal in wild-type but not A-IV−/− mice andCCK1R receptor blockade with devazepide (10 μg/100 g), abolished PYY3–36-induced inhibition of gastric emptying. PYY3–36-induced inhibition of food intake in both ad libitum-fed and 16-h fasted mice was unaltered in A-IV−/− mice, compared with wild-type controls, or by CCK1R receptor blockade with devazepide. PYY3–36 activated neurons in the midregion of the nucleus of the solitary tract (bregma −7.32 to −7.76 mm) in A-IV+/+ mice; this was measured by immunohistochemical localization of Fos protein. PYY3–36-induced Fos expression was significantly reduced by 65% in A-IV+/+ mice pretreated systemically with the sensory neurotoxin capsaicin (5 mg/100 g), 78% by the CCK1R antagonist, devazepide (10 μg/100 g), and 39% by the Y2R antagonist, BIIE0246 (200 and 600 μg/100 g) and decreased by 67% in apo A-IV−/− mice, compared with A-IV+/+ controls. The data suggest a role for apo A-IV and the CCK1R in PYY3–36-induced activation of the vagal afferent pathway and inhibition of gastric emptying, but this is likely not the pathway mediating the effects of PYY3–36 on food intake.
Benzo[a]pyrene Induces Apoptosis in RL95-2 Human Endometrial Cancer Cells by Cytochrome P450 1A1 Activation
Authors: Kim Ji Young , Chung Jin-Yong , Park Ji-Eun , Lee Seung Gee , Kim Yoon-Jae , Cha Moon-Seok , Han Myung Seok , Lee Hye-Jeong , Yoo Young Hyun , Kim Jong-Min
Published: July 2007

Benzo[a]pyrene (B[a]P) has been shown to be an inducer of apoptosis in some cell types. To date, due to the lack of an appropriate model system, studies of the cellular and biochemical mechanism(s) by which B[a]P induces apoptosis have been focused on Hepa1c1c7 cells. Moreover, the precise relationship between the bioactivation of B[a]P by CYP1A1 or CYP1B1 and the occurrence of cytotoxicity-mediated apoptosis requires further elucidation. In the present study, we showed that B[a]P-induced apoptosis in RL95-2 cells is accompanied by the activation of caspases. In addition, the mitochondrial changes, including the decrease of mitochondrial potential and the release of mitochondrial cytochrome c and second mitochondria-derived activator of caspases/direct inhibitor of apoptosis protein binding protein with low PI (Smac/DIABLO) into the cytosol, support the suggestion that the mitochondrial pathway is robustly associated with B[a]P-evoked apoptosis. This study showed the involvement of the nuclear translocation of mitochondrial apoptosis-inducing factor in B[a]P-induced apoptosis of RL95-2 cells. Exposure to B[a]P up-regulates aryl hydrocarbon receptor, heat-shock protein 90, cytochrome P450 1A1 (CYP1A1), cytochrome P450 1B1 (CYP1B1), and epoxide hydrolase significantly, which might be prerequisites for the conversion of B[a]P to B[a]P-7,8-dihydroxy-9,10-epoxide. Although both CYP1A1 and CYP1B1 proteins were up-regulated significantly by B[a]P, only CYP1A1 exhibited activity. Thus, CYP1A1 is believed to be a central oxidative enzyme that is ultimately required for formation of B[a]P-7,8-dihydroxy-9,10-epoxide from B[a]P in RL95-2 cells. Altogether, our data showed that RL95-2 cells are susceptible to apoptosis by exposure to B[a]P and that B[a]P-evoked apoptosis is mediated predominantly by the activation of CYP1A1. Here we suggest that RL95-2 cells are an excellent model for the investigation of xenobiotic mechanisms associated with CYP1A1 as well as CYP1B1.
C-Type Natriuretic Peptide Regulates Cellular Condensation and Glycosaminoglycan Synthesis during Chondrogenesis
Authors: Woods Anita , Khan Sameena , Beier Frank
Published: July 2007

C-type natriuretic peptide (CNP) has recently been identified as a key anabolic regulator of endochondral bone growth, but the cellular and molecular mechanisms involved are incompletely understood. Although CNP has been shown to stimulate proliferation and hypertrophic differentiation of growth plate chondrocytes, it is unknown whether CNP affects the earliest stages of endochondral bone development, condensation of mesenchymal precursor cells, and chondrogenesis. Here we demonstrate that CNP increases the number of chondrogenic condensations of mouse embryonic limb bud cells in micromass culture. This is accompanied by increased expression of the cell adhesion molecule N-cadherin. In addition, CNP stimulates glycosaminoglycan synthesis as indicated by increased Alcian blue staining. However, expression of the chondrogenic transcription factors Sox9, -5, and -6 or of the main extracellular matrix genes encoding collagen II and aggrecan is not affected by CNP. Instead, we show that CNP increases expression of enzymes involved in chondroitin sulfate synthesis, a required step in the production of cartilage glycosaminoglycans. In summary, we demonstrate a novel role of CNP in promoting chondrogenesis by stimulating expression of molecules involved in cell adhesion molecules and glycosaminoglycan synthesis.
Estrogen Is Not Essential for Full Endometrial Restoration after Breakdown: Lessons from a Mouse Model
Authors: Kaitu’u-Lino Tu’uhevaha J. , Morison Naomi B. , Salamonsen Lois A.
Published: July 2007

The current dogma surrounding endometrial regeneration after menses includes a critical need for estrogen-primed proliferation. Although some evidence suggests that estrogen may not be required for the initial reepithelialization of the uterine surface, it is widely believed that it is essential for successful stromal renewal. This study aimed to identify proliferating cell types during endometrial repair and to examine whether estrogen is required for successful repair using a previously developed mouse model. In the model, decidualization is artificially induced, and progesterone support withdrawn; the endometrial tissue progressively breaks down by 24 h after progesterone withdrawal and by 48 h has usually undergone complete repair. Although the mice are ovariectomized, restoration of both the stromal and epithelial components proceeds rapidly after breakdown and results in what appears to be a normal endometrium. However, potential estrogenic influences from extraovarian sources (particularly the diet and fat) remain. In this study, complete removal of extraovarian estrogen was achieved by maintenance of animals on a soy-free diet and administration of aromatase inhibitor letrozole. No significant differences in uterine weight or estrogen-responsive genes lactoferrin and progesterone receptor were observed compared with control ovariectomized but otherwise untreated mice, whereas significantly higher measurements were obtained from an estrogen-added group. Importantly, no significant difference in the rate of endometrial repair was observed in the complete absence of estrogen, demonstrating that estrogen is not essential for complete endometrial restoration in this model.
Critical thermal maxima in knockdown-selectedDrosophila: are thermal endpoints correlated?
Authors: Folk Donna G. , Hoekstra Luke A. , Gilchrist George W.
Published: July 2007

To explore the correlation of traits linked to thermotolerance, we compared three thermal endpoints (knockdown temperature and two critical thermal maxima) among replicate populations of Drosophila melanogasterselected for high, or low, knockdown temperature. The high knockdown flies maintain normal posture and locomotor ability within a knockdown column at temperatures ⩾40°C, whereas the low knockdown flies fall out of the column at much cooler temperatures (∼35°C, on average). The critical thermal maximum (CTmax) for respiratory control in the selected knockdown populations was determined by analyzing CO2output of individuals during exposure to a temperature ramp (from 30°C to>45°C) and was indicated by an abrupt alteration in the pattern of CO2 release. The CTmax for locomotor function was determined by monitoring activity (concurrent with CO2analysis) during the temperature ramp and was marked by the abrupt cessation of activity. We hypothesized that selection for high knockdown temperature may cause an upward shift in CTmax, whereas selection for low knockdown may lower CTmax. Correlations among the three thermal endpoints varied between the high and low knockdown flies. Finally, we compared metabolic profiles, as well as Q10 values, among the high and low knockdown males and females during the temperature ramp.
Growth in the slow lane: protein metabolism in the Antarctic limpetNacella concinna(Strebel 1908)
Authors: Fraser Keiron P. P. , Clarke Andrew , Peck Lloyd S.
Published: July 2007

Growth rates in Antarctic ectotherms are generally considered to be low in comparison to temperate and tropical species. Food consumption plays a major role in determining animal growth rates, but once food is ingested soft tissue growth rates are largely determined by the protein synthesis retention efficiency (PSRE), a measure of the efficiency with which proteins are synthesised and retained as protein growth. The effect of water temperatures on the PSRE of polar organisms has not previously been investigated, and it is possible that reduced PSRE at polar water temperatures may at least partially explain low growth rates in Antarctic organisms. We also currently lack any information on the potential effects of predicted increases in seawater temperatures on protein metabolism in Antarctic ectotherms. We have measured seasonal protein synthesis, degradation and growth rates in free-ranging Antarctic limpets (Nacella concinna), together with protein synthesis rates at temperatures ranging between –1.5°C and 6.0°C. PSRE were not significantly different in summer (15.69±4.41%) or winter(20.59±4.45%), but values were considerably lower than those previously reported in temperate and tropical species. A meta-analysis of published ectotherm PSRE suggested there was a positive relationship with temperature(y=449.9–114.9x, r2=28.8%, P<0.05). In turn, this suggests that temperature may be an important factor in determining ectotherm growth efficiency via an influence on PSRE. Maximal fractional and absolute protein synthesis rates occurred at ∼1°C in N. concinna, the approximate summer water temperature at the study site, and protein synthesis rates decreased above this temperature. In the absence of adaptation, predicted increases in Antarctic water temperatures would result in reduced, rather than increased,rates of protein synthesis and, in turn, possibly growth.
Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude
Authors: Arampatzis Adamantios , Karamanidis Kiros , Albracht Kirsten
Published: July 2007

Tendons are able to remodel their mechanical and morphological properties in response to mechanical loading. However, there is little information about the effects of controlled modulation in cyclic strain magnitude applied to the tendon on the adaptation of tendon's properties in vivo. The present study investigated whether the magnitude of the mechanical load induced as cyclic strain applied to the Achilles tendon may have a threshold in order to trigger adaptation effects on tendon mechanical and morphological properties. Twenty-one adults (experimental group, N=11; control group, N=10) participated in the study. The participants of the experimental group exercised one leg at low-magnitude tendon strain (2.85±0.99%) and the other leg at high-magnitude tendon strain (4.55±1.38%) of similar frequency and volume. After 14 weeks of exercise intervention we found a decrease in strain at a given tendon force, an increase in tendon-aponeurosis stiffness and tendon elastic modulus and a region-specific hypertrophy of the Achilles tendon only in the leg exercised at high strain magnitude. These findings provide evidence of the existence of a threshold or set-point at the applied strain magnitude at which the transduction of the mechanical stimulus may influence the tensional homeostasis of the tendons. The results further show that the mechanical load exerted on the Achilles tendon during the low-strain-magnitude exercise is not a sufficient stimulus for triggering further adaptation effects on the Achilles tendon than the stimulus provided by the mechanical load applied during daily activities.
Vitamin C Deficiency and Scurvy Are Not Only a Dietary Problem but Are Codetermined by the Haptoglobin Polymorphism
Authors: Delanghe Joris R , Langlois Michel R , De Buyzere Marc L , Torck Mathieu A
Published: July 2007

Ascorbic acid (vitamin C) is prone to oxidation in vivo. The human plasma protein haptoglobin (Hp) shows a genetic polymorphism with 3 major phenotypes (Hp 1-1, Hp 2-1, and Hp 2-2) that show important functional differences. Despite an adequate nutritional supply, in Hp 2-2 individuals (most common among Asian populations) vitamin C is markedly lower in concentration and particularly prone to oxidation in vivo. Therefore, susceptibility to subclinical and clinical vitamin C deficiency (scurvy) is partly genetically determined. The genetic advantage of the Hp1 allele as a vitamin C stabilizing factor helps to elucidate the direction and successes of long-distance sea crossing human migrations in history. Clinical trials demonstrated Hp phenotype–related effects of antioxidant treatment. Because vitamin C is a first line antioxidant, Hp polymorphism and its effects on vitamin C have major clinical consequences; a marked difference in genetic susceptibility toward atherosclerosis between Hp phenotypes is attributable to variation in LDL oxidation. The classical view of vitamin C and scurvy being a pure nutritional condition needs to be updated. These findings should foster research investigating the role of Hp polymorphism in human disease, and in vitamin C deficiency and atherosclerosis in particular.
Coolant Development in Asia
Authors: Egawa Hiroshi , Mori Yasuaki , Abel Michael L.
Published: July 2007

Historically speaking, there have always been three major regions, North America, Europe, and Asia, where antifreeze/coolant developments take place independently. These developments were based on the perceived needs of the engine manufacturers, influenced by governmental/regulatory authorities, and heavily influenced by the requirements geography placed upon automobile manufacturers [1–3]. In the early days of ethylene glycol based engine coolants, simple inhibitor systems based on borates, phosphates, etc., and utilizing a soft metal inhibitor were sufficient to satisfy the needs of a cast iron engine and copper brass radiator. With the advent of aluminum engines and their rapid usage growth throughout the 1980s and 1990s, engine manufacturers of the regions began to place more stringent requirements on the anticorrosion performance of the OEM coolants. Based on the specific strategies utilized by the cooling system component manufacturers, divergent requirements began to be placed upon the coolant makeup. This paper will speak generally to the regional history of coolant trends and specifically on the activity for coolant development in Asia.
Paving Design: Is Rigid-Fix External Stone Paving the Way to Go?
Authors: Hensel Hans-Dieter
Published: July 2007

Recent investigations into a number of paving failures in Australia have shown that very little is understood about the many aspects intrinsic to rigid-fix (stuck down) paving. This paper examines and documents some of the factors that can determine the success or failure of paving (assuming a high standard of workmanship). Additionally, it has become clear that most engineers who investigate paving failures fail to fully understand the complexities and interplay of the many factors. Such lack of knowledge leads to poor design, poor supervision, and ultimately poor performance. There are basically three types of paving systems—adhesive/mortar fix, sand-bedded, and setts/cobblestones in a soft mortar. All three systems are being used in Australia but there is undoubtedly an overriding rigid-fixing mentality. By fixing stone to a solid concrete base so that it cannot move is probably seen by most engineers and architects as the most straight-forward and most controllable solution. However, on analysis, it is a system that is subject to numerous potential lines of failure. Not only is there the nature of the stone itself such as the mineral composition, strengths, thermal characteristics, and porosity, but also the environment into which it is placed, the types of loading it is subject to, and how it is fixed. Stability of the base (including shrinkage), expansion/construction joints, size, thickness and shape of the pavers, the laying pattern, type of adhesive, thermal conditions at the time of fixing, influence of salts and water, and sealing, all play a significant role in determining the success or otherwise of rigid-fix paving.
Prediction of Strontium Sulfate Scale Formation in Oilfield Environment
Authors: Ezuber Hosni M.
Published: July 2007

An easy and reliable method for predicting a scale tendency of strontium sulfate as a function of several variables including sodium chloride brine composition, temperature, and pressure effect is developed. The effect of the amount of sulfate tied up as [MgSO40] on SrSO4 solubility is also considered. The magnesium sulfate dissociation constants and strontium sulfate experimental solubility data is fitted in mathematical equations. These equations can be easily used to determine SrSO4 scaling tendency in environments common to oil field brines. The reliability and key features of the prediction method are illustrated in the text with oilfield well cases. Results obtained using the present model are in good agreement with field observation. The method presented in this study is easy to use, reliable, and can be applied to any producing wells where SrSO4 occurs.
Stiffness Considerations in Dimension Stone Anchorage Design
Authors: Conroy Kevin , Hoigard Kurt R.
Published: July 2007

Modern building facade design concepts consider all cladding materials, including dimension stone cladding, as nonstructural elements designed to transmit localized gravity and lateral loads to the primary building structural elements. In practice, the structural backup behind dimension stone cladding can take a wide variety of forms, including cast-in-place concrete shear walls, brick and concrete masonry units, aluminum curtain wall system framing, hot and cold rolled steel subframes, and precast concrete panels and members. The flexural stiffness of these backup systems can vary widely, with cast-in-place concrete shear walls on one end of the stiffness spectrum and aluminum curtain framing on the other. The stiffness of dimension stone cladding relative to the backup system can have a significant effect both on the stresses induced in the cladding and the loads transmitted through the cladding anchors. Likewise, the stiffness of the anchor elements and the backup system can affect the loading and stress distribution within the cladding panels. This paper addresses some of the issues associated with the interaction of dimension stone cladding panels, panel anchors, and metal backup structures, and the effects of relative stiffness on load and stress distributions. Information is presented that was obtained from laboratory tests and analyses for new designs, as well as investigations of dimension stone cladding failures.
Material Strength Considerations in Dimension Stone Anchorage Design
Authors: Lammert Brian T. , Hoigard Kurt R.
Published: July 2007

One of the most important aspects of designing dimension stone cladding involves determining the configuration, size, and spacing of the anchorages that will affix the stone panels to the underlying building substrate. Information from many sources, including material strength testing, anchorage strength testing, and knowledge of the stress states created within stone cladding panels by loaded anchorages, is crucial to this process. In this paper, relationships are examined between material strength, anchorage strength, and induced stress states for four common anchorage configurations: edge dowels, Type 31 back anchors, and edge kerfs with strap and split-tail anchors. For each of these four anchor types, the relevant material and anchorage strength test data obtained for a medium-grained granite, in conjunction with finite element computer analyses of the stress states induced in the stone panels by the anchors and within the material strength test specimens, are presented. Material strength test configurations evaluated include ASTM C 880 Standard Test Method for Flexural Strength of Dimension Stone, ASTM C 99 Standard Test Method for Modulus of Rupture of Dimension Stone, and a proposed test for punching shear currently under consideration by ASTM Subcommittee C18.01. All anchorage strength tests were performed in accordance with ASTM C 1354 Standard Test Method for Strength of Individual Stone Anchorages in Dimension Stone.
Efficient Derivation of Embryonic Stem Cells by Inhibition of Glycogen Synthase Kinase-3
Authors: Umehara Hiroki , Kimura Tohru , Ohtsuka Satoshi , Nakamura Toshinobu , Kitajima Kenji , Ikawa Masahito , Okabe Masaru , Niwa Hitoshi , Nakano Toru
Published: July 2007

Embryonic stem (ES) cells are derived from the inner cell mass (ICM) of blastocysts. The use of ES cells as a source of differentiated cells holds great promise for cell transplantation therapy. The efficiency of ES cell derivation is affected by genetic variation in mice; that is, some mouse strains, such as C57BL/6, are amenable to ES cell derivation, whereas others, such as BALB/c, are refractory. Developing an efficient method to establish ES cells from strains of various genetic backgrounds should be valuable for derivation of ES cells in various mammalian species, including human. Although it is well-established that various signaling pathways, including phosphoinositide 3-kinase (PI3K)/Akt and Wnt/β-catenin, regulate the maintenance of ES cell pluripotency, little is known about the signaling pathways involved in the derivation of ES cells from ICMs. In this study, we demonstrated that inhibition of glycogen synthase kinase-3 (GSK-3), one of the crucial molecules in the regulation of the Wnt/β-catenin, Hedgehog, and Notch signaling pathways, dramatically augmented ES cell derivation from both C57BL/6 and BALB/c mouse strains. In contrast, Akt signaling activation enhanced the growth of ICM but did not increase the efficiency of ES cell derivation. Our study establishes an efficient means for ES cell derivation by pharmacological inhibition of GSK-3.

Disclosure of potential conflicts of interest is found at the end of this article.
Concise Review: Role and Function of the Ubiquitin-Proteasome System in Mammalian Stem and Progenitor Cells
Authors: Naujokat Cord , Šarić Tomo
Published: July 2007

Highly ordered degradation of cell proteins by the ubiquitin-proteasome system, a sophisticated cellular proteolytic machinery, has been identified as a key regulatory mechanism in many eukaryotic cells. Accumulating evidence reveals that the ubiquitin-proteasome system is involved in the regulation of fundamental processes in mammalian stem and progenitor cells of embryonic, neural, hematopoietic, and mesenchymal origin. Such processes, including development, survival, differentiation, lineage commitment, migration, and homing, are directly controlled by the ubiquitin-proteasome system, either via proteolytic degradation of key regulatory proteins of signaling and gene expression pathways or via nonproteolytic mechanisms involving the proteasome itself or posttranslational modifications of target proteins by ubiquitin or other ubiquitin-like modifiers. Future characterization of the precise roles and functions of the ubiquitin-proteasome system in mammalian stem and early progenitor cells will improve our understanding of stem cell biology and may provide an experimental basis for the development of novel therapeutic strategies in regenerative medicine.

Disclosure of potential conflicts of interest is found at the end of this article.
External source monitoring in a real‐life event: developmental changes in ability to identify source persons
Authors: Sugimura Tomoko
Published: July 2007

The present study investigated young children's and adults' external source‐monitoring abilities with respect to facial identification accuracy for complex live events. Five‐ to 6‐ year‐olds and adults watched a magic show in which three different female magicians (i.e. source persons) performed three different kinds of magic tricks each. After approximately 1 month, the participants were asked to recognize what kinds of magic tricks had been performed, to make face identifications as to which magician had performed those magic tricks and to recognize those magicians' attributes. Results showed that both young children and adults had more difficulty with identifying source persons than recognizing them in a real‐life event in which a number of persons appeared. Especially for young children, low credibility was shown not only for the source memories but also for the recognition memories of the source person attributes. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of CaO sintering on cyclic CO2 capture in energy systems
Authors: Sun P. , Grace J. R. , Lim C. J. , Anthony E. J.
Published: July 2007

The importance of calcium‐based sorbents, especially natural limestones, for CO2 removal necessitates an investigation into the sorbent decay mechanism. This study starts from pore size distributions for samples from tests under various calcination/carbonation cycling conditions. A sintering model is formulated to describe the cyclic behavior of sorbents during cyclic calcination and carbonation. It explains the similar reversibility shown by sorbents under different test conditions. A balance between shorter cumulative sintering time and higher calcination rates appears to be responsible for the similar degrees of sintering and sorbent reversibility. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Drying technology for woody biomass for fine grinding by vibration mills
Authors: Kobayashi J. , Itaya Y. , Tsukada S. , Mizuno K. , Ueda M. , Morikawa H. , Sugimoto T. , Ueda Y. , Oshika Y. , Kobayashi N. , Hatano S. , Mori S.
Published: July 2007

An effective fine grinding technology for woody biomass using a new vibration mill is proposed and evaluated in this study. Grinding properties of woody biomass depend largely on its moisture content. In this study, the drying behavior of woody biomass and the effect of moisture content on fine grinding with a vibration mill are discussed. Simultaneous drying and pulverization of woody biomass using a continuous vibration mill was carried out and the drying characteristics were investigated. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis and characterization of poly(ϵ‐caprolactone)–graphite oxide composites
Authors: Hua Lei , Kai Weihua , Inoue Yoshio
Published: July 2007

The composites of poly(ε‐caprolactone) (PCL) and graphite oxide (GO) were successfully synthesized by ring‐opening polymerization of ε‐caprolactone with GO as the initiator. The composites with different GO content were synthesized and an exfoliated structure was found for all the composites from the wide angle X‐ray diffraction study. An astounding nucleating effect of GO on PCL crystallization was observed due to the good dispersion of GO in the composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Preparation and properties of novel green poly(ether–ester urethane)s insulating coatings based on polyols derived from glycolyzed PET, castor oil, and adipic acid and blocked isocyanate
Authors: Moeini Hamid Reza
Published: July 2007

To utilize renewable resource raw materials as well as trying to recycle polymeric materials, three new polyols (PEE1‐3) were prepared from trasesterification reaction of postconsumer poly(ethylene terephtalate) (PET), different molecular weights of poly(ethylene glycol) (PEG), and glycerine. The intermediate hydroxyl‐terminated compounds were chain extended via esterification reaction with adipic acid (AA), and the products were reacted with castor oil (CO). These polyols were cured by blocked isocyanate (BIC) made from trimethylol propane, toluene diisocyanate, and N‐methyl aniline. All of starting materials and final films were characterized by conventional methods. Curing condition was optimized via gel content measurements. Crosslink density of samples was determined via equilibrium swelling method, using Flory–Rehner equations. Effects of structural parameters on physical, electrical, mechanical, and dynamic mechanical (DMTA) properties of the polyurethane coatings were investigated. Comparison of results with commercially available product shows that the prepared green coatings have environmental benefits as well as high performance for metal insulator coatings too. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Humidity‐responsive polymeric films based on AOT‐water reverse microemulsions
Authors: Marszalek Jolanta E. , Pojman John A. , Aultman Kayce Leard , Hoyle Charles E. , Whitehead Joe B.
Published: July 2007

Hydrophobic polymer films, having an aqueous phase distributed throughout the matrix, were formed by polymerizing a solution of dodecyl acrylate and 1,6 hexanediol diacrylate containing nanometer‐sized drops of water stabilized by sodium bis(2‐ethylhexyl) sulfosuccinate (AOT). Photopolymerization‐induced aggregation of the water drops and/or phase separation occurred, as the initially clear solutions became opaque films. The polymerized films became clear, as the relative humidity was reduced. Clear films still contained 20–50% of the initial water. The transition from opaque to clear films was reversible provided that the film did not become completely dry and form cracks. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of nanoscale fully vulcanized acrylic rubber powders on crystallization of poly(butylene terephthalate): Nonisothermal crystallization
Authors: Huang Jiann‐Wen
Published: July 2007

Poly(butylene terephthalate) (PBT) was blended with different content (1, 3, and 6 wt %) of nanoscale fully vulcanized acrylic rubber (FVAR) powders in a twin extruder to prepare PBT/FVAR composites (PBT/FVAR1, PBT/FVAR3, and PBT/FVAR6).The influence of different content (1, 3, and 6 wt %) of nanoscale FVAR powder on the nonisothermal crystallization behavior of PBT was investigated by using differential scanning calorimeter. The nonisothermal crystallization data were analyzed using Avrami, Ozawa, and Liu‐Mo methods. The validity of kinetic models on the nonisothermal crystallization process of PBT and PBT/FVAR blends was discussed. All kinetic parameters showed that the “crystallization rate” followed the order: PBT > PBT/FVAR1 > PBT/FVAR3 > PBT/FVAR6 at a given cooling rate during experimental crystallization. However, when undercooling was taken into consideration, crystallization ability followed the order: PBT > PBT/FVAR6 > PBT/FVAR3 > PBT/FVAR1. A modified the Lauritzen–Hoffman equation was used to derive nucleation parameter (Kg) derived from nonisothermal crystallization. The results revealed that FVAR particles hindered the crystallization; however higher content of FVAR powders acted as heterogeneous nuclei in the nucleation stage to facilitated the crystallization of PBT. The dependence of the effective activation energy on conversion was evaluated on the basis of Friedman equation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Loss of Ostracoda biodiversity in Western Mediterranean wetlands
Authors: Poquet José M. , Mezquita Francesc , Rueda Juan , Miracle María R.
Published: July 2007

The coastal area of Valencia (Spain) in the Western Mediterranean is rich in freshwater and brackish wetlands. These areas are mostly protected for bird conservation but are also highly affected by human impacts. Six shallow lakes located in Ramsar wetland sites of this area were studied in order to assess past and present ostracod biodiversity and relate it to the status of the lakes, taking into consideration the indicator value of these easily fossilizable crustaceans.

In all the wetlands studied, ostracod taphocoenoses showed much higher species richness than the corresponding biocoenoses. This is expected from the time accumulative character of the taphocoenosis, but the trend is clearly evident in the most disturbed sites which indicated loss of ostracod diversity owing to human impacts.

By considering the ecology of most frequent species, multivariate ordination of both tapho‐ and biocoenoses showed trends within and between lakes in their limnological status, which were related mainly to water chemistry, and also to temporality and eutrophication to a certain extent. Some lakes have apparently lost most of their past ostracod community owing to an increasing trophic status in some cases and to modifications of the hydrological regime in others.

Copyright © 2007 John Wiley & Sons, Ltd.
Gas Hold‐Up Evaluation Using the Analytical Solution of the Axial Dispersion Model: Comparison with Static Measurement Results
Authors: Veverková‐Majírová H. , Pinelli D. , Magelli F. , Siyakatshana N. , Kudrna V. , Machoň V.
Published: July 2007

A comparison was made of the gas hold‐up values obtained in an aerated mixing vessel of high aspect ratio by both visual measurement of the liquid level rise due to aeration, agitation and processing, and the residence time distribution (RTD) curves of the gas flowing in the vessel. For the description of the RTD curves, the one‐dimensional dispersion model with Danckwerts' boundary conditions was adopted and the corresponding equations were solved analytically. Experiments have been performed with both coalescent and non‐coalescent systems. It was found that gas hold‐up values determined with these two methods are in very good agreement. This also provides additional support for the use of the proposed model.
Biomimetic Synthesis and Characterization of Mesoporous Titanium Dioxide
Authors: Zhao H.‐S. , He W. , Feng Y.‐J. , Jia X.‐T. , Zhang X.‐D. , Li Z.‐M. , Yan S.‐P. , Zhou W.‐J.
Published: July 2007

Mesoporous titanium dioxide (TiO2) with a pore size range from 5–7 nm was synthesized by a sol‐gel method using biosurfactant phosphatidylcholines as an organic template. Titanium tetrabutoxide (TBOT) was used as the precursor. A very fine mesoporous structure formed in the particle was maintained after a heat treatment at 700 °C. Low‐angle X‐ray powder diffraction (XRD) and a pore size distribution curve revealed the existence of the mesoporous structure. Transmission Electron Microscopy (TEM) and N2 adsorption–desorption isotherms were utilized for further characterization. A significant red shift in the UV‐VIS spectrum of the porous material was observed, which could be explained by the energy band theory. The results confirmed the synthesis of mesoporous TiO2.
Prediction via Neural Networks of the Residual Hydrogen Peroxide used in Photo‐Fenton Processes for Effluent Treatment
Authors: Guimarães O. L. C. , Aquino H. O. Q. , Oliveira I. S. , Villela Filho D. N. , Izario Filho H. J. , Siqueira A. F. , Silva M. B.
Published: July 2007

This communication proposes the use of neural networks in the prediction of residual concentrations of hydrogen peroxide from the treatment of effluents through Advanced Oxidative Processes (AOP's), in particular, the photo‐Fenton process. To verify the efficiency of the oxidative process, the Chemical Oxygen Demand (COD) parameter, the values of which may be modified by the presence of oxidizing agents such as residual hydrogen peroxide, is frequently taken in account. The analysis of the H2O2 interference was performed by spectrophotometry at 450 nm wavelength, via the monitoring of the reaction of ammonia with metavanadate. The results of the hydrogen peroxide residual concentration were modeled via a feedforward neural network, with the correlation coefficients between actual and predicted values above 0.96, indicating good prediction capacity.
Induction Time of Reaction Crystallization of Silver Nanoparticles
Authors: Ghader S. , Manteghian M. , Kokabi M. , Mamoory R. S.
Published: July 2007

This paper describes the measurement of induction time in the reaction crystallization of silver nanoparticles at different temperatures and supersaturations, and compares it with classical nucleation theory. Silver nanoparticles are synthesized by a reaction of silver nitrate with hydrazine in the presence of sodium citrate as stabilizer. Induction time is estimated from an absorption‐time graph obtained by monitoring the absorption of the solution after creation of supersaturation. The results show that induction time decreases with increasing supersaturation and temperature. The classical nucleation theory can well predict experimental data. Interfacial tension is estimated at different temperatures and compared with two correlations for calculation of interfacial tension.
A Tale of Two Complexes, [PtMen(RNCHCHNR)] (n = 2 and n = 4, R = Cyclohexyl): Why do PtII and PtIV Complexes Exhibit Virtually Identical Redox Behavior and Colors?
Authors: Hasenzahl Steffen , Hausen Hans‐Dieter , Kaim Wolfgang
Published: July 2007

In spite of their very similar cyclic voltammograms, absorption spectra, and solvatochromic behavior, the two 1,4‐diazabutadiene title complexes exhibit markedly different photoreactivities and underlying electronic structures, as evident from absorption and EPR spectra of the persistent anion radical forms. The lowest excited state of the nonphotoreactive PtII system [(CyNCHCHNCy)‐PtMe2] has MLCT (metal‐to‐ligand charge‐transfer, 5d → π*) character, and the EPR spectrum of the corresponding anion radical at 〈g〉 = 2.016 exhibits sizable metal/ligand orbital mixing. On the other hand, the structurally characterized PtIV complex [(CyNCHCHNCy)‐PtMe4] (C2/c; a = 2021.6(2), b = 805.3(1), c = 1254.2(1) pm; β = 111.05(1)°; V = 1905.7(4) × 106 pm3; Z = 4) has a lowlying photoreactive LLCT (ligand‐to‐ligand charge‐transfer, σPtC → π*) excited state in which the axial PtC bonds are activated, as already suggested by the longer PtC(ax) bonds (214.0(8) pm) relative to PtC(eq) in the ground state (204.5(5) pm). The anion radical of the PtIV complex has lost the long‐wavelength absorption band in the visible; it shows a well‐resolved EPR spectrum at 〈g〉 = 1.9945 with π‐ligand and 195Pt hyperfine structure and a small g anisotropy. A qualitative MO scheme is presented to account for the similar frontier‐orbital energy differences despite dissimilar underlying electronic structures.
Passive Template Effects and Active Acid‐Base Involvement in Catalysis of Organic Reactions
Authors: Pieters Roland J. , Huc Ivan , Rebek Julius
Published: July 2007

A series of receptors were prepared all containing two adenine binding sites linked by various spacers. Their ability to act as templates in the coupling of two adenine derivatives, an active ester and an amine, in CHCl3 was evaluated. The accelerations varied from none to 700‐fold. Binding studies of the coupling product with these templates confirmed involvement of both binding sites. When the spacer was a 1,10‐phenanthroline unit, an efficient hydrolysis reaction of the active ester was observed. Another series of receptors were prepared containing one adenine receptor and various polar functional groups. The molecules were evaluated as catalysts in the coupling of an adenine‐derived active ester and n‐butyl‐amine. The orientation as well as the nature of the functional group greatly influenced the coupling rate. A carboxylate group was most effective, accelerating the intracomplex reaction 250‐fold.
Reactions of the “Naked” Fluoride Ion: Syntheses and Structures of SeF and BrF
Authors: Mahjoub Ali Reza , Zhang Xiongzhi , Seppelt Konrad
Published: July 2007

1,1,3,3,5,5‐Hexamethylpiperidinium fluoride (pip+F−) and 1,2‐dimethylpropyltrimethylammonium fluoride have been prepared. They dissolve in fluorohydrocarbons (CH2F2, CF3‐CHF‐CF3, CHF3) even at very low temperatures. The nature of these solutions is indicated by the crystal structure of the adduct pip+F−·4CH2F2, which shows (C)H…F bridging. The high fluoride activity is exemplified by the previously unknown reaction between SeF and F− to yield SeF. The salt pip+BrF is obtained by a metathesis reaction of Cs+BrF with pip+F−. The distortion of the SeF structure from octahedral symmetry is intermediate between IF (strongly distorted) and BrF (octahedral). The electron‐pair repulsion model is checked against these results.
Reversibility in the Reaction of Cyclohexadienyl Radicals with Oxygen in Aqueous Solution
Authors: Fang Xingwang , Pan Xianming , Rahmann Anja , Schuchmann Heinz‐Peter , von Sonntag Clemens
Published: July 2007

Hydroxyl radicals were generated radiolytically and reacted with a number of benzene derivatives (PhH). In the presence of oxygen, the hydroxycyclohexadienyl radicals thus formed were converted into their corresponding peroxyl radicals. Pulse radiolysis has shown the oxygen addition (forward reaction, f) to be reversible (reverse reaction, r) [Eq. (1)]. The peroxyl radicals can eliminate HO to yield phenols, alongside some ring‐fragmentation products (product‐forming reaction, p). The rate constants for the forward and reverse reactions (kf and kr) and the corresponding stability constants K (= kf/kr) were determined for the hydroxy‐cyclohexadienyl radicals derived from anisole, toluene, fluorobenzene, benzene, chlorobenzene, benzyl chloride, benzoate ion, phenylalanine, and terephthalate ion. The constants kf lie between 8 × 108 (anisole) and 1.6 × 107 dm3 mol−1 s−1 (terephthalate ion), and kr between 7.5 × 104 (toluene) and 3.4 × 103 s−1 (terephthalate ion). The stability constants lie between 2.6 × 104 (benzene) and 3.3 × 103 dm3 mol−1 (phenylalanine). The rate constants for the product‐forming reactions kp are between 5.5 × 103 (anisole) and 3.4 × 102 s−1 (benzoate). For the peroxyl radical derived from phenylalanine, a bond dissociation energy of 5.5 kcal mol−1 has been derived. A number of hydroxy‐cyclohexadienyl radicals (e.g., those derived from benzoic acid, ethylbenzoate, benzonitrile, and nitrobenzene) react too slowly to allow the equilibrium constant to be determined by means of pulse radiolysis. These reactions have rate constants kf in the order of 5 × 106 dm3 mol−1 s−1, except for nitrobenzene where the reaction is too slow for measurement. The rate constants kr are below 500 s−1, and the product‐forming reaction is too slow to be detected by pulse radiolysis. γ‐Radiolysis of N2O/O2(4:1)‐saturated aqueous solutions of benzonitrile gave dimeric compounds (e.g., dicyanobiphenyls) in low yield, alongside the three isomeric phenols; this again proves the low reactivity of its hydroxycyclohexadienyl radical toward oxygen.
New PF3 and Carbonyl Chemistry of Tantalum
Authors: Ellis John E. , Warnock Garry F. , Barybin Mikhail V. , Pomije Marie K.
Published: July 2007

Reduction of [TaCl5] by six equivalents of alkali metal naphthalenide in 1,2‐dimethoxyethane at −60°C followed by treatment with gaseous PF3 provides the first homoleptic phosphane complex containing tantalum in the −1 oxidation state, [Ta(PF3)6]−. This can be protonated by concentrated sulfuric acid to yield the previously unknown highly acidic and volatile hydride [HTa(PF3)6]. An improved normal‐pressure synthesis of [Ta(CO)6]− is described. Reduction of the latter species by sodium in liquid ammonia gives the carbonyl trianion [Ta(CO)5]3− which undergoes monoprotonation and stannylation to form [HTa(CO)5]2− and [Ph3SnTa(CO)5]2−, respectively. The hydride is a useful precursor to [(Ph3PAu)3Ta(CO)5], the only known gold cluster of tantalum.
A Theoretical Model for the Active Site of Nitrogenase
Authors: Stavrev Krassimir K. , Zerner Michael C.
Published: July 2007

A model for the active site of nitrogenase is suggested and examined by means of the intermediate neglect of differential overlap (INDO) quantum mechanical method. The initial steps of the nitrogen fixation process are discussed within the framework of the present model, and it is shown that of several binding sites, initial location of the nitrogen molecule inside the MoFe cofactor is favored. Possible pathways for electron and proton delivery to the active site are also suggested on the basis of electrostatic potential calculations.