bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi‐Step Synthesis and Biological Evaluation of Analogues of Insulin Secretagogue (2S,3R,4S)‐4‐Hydroxyisoleucine
Authors: Aouadi Kaïss , Lajoix Anne‐Dominique , Gross René , Praly Jean‐Pierre
Published: November 2008

A series of stereochemically defined analogues of (2S,3R,4S)‐4‐hydroxyisoleucine and related α‐hydroxy acids have been prepared by multi‐step routes from D‐glucose, whereas ketolization between TBDMS‐protected hydroxypropanone and ethyl isocyanoacetate led to racemic analogues. Bioassays showed that of eight newly synthesized compounds, two of them presented an interesting statistical trend to increase glucose‐induced insulin secretion when tested in isolated rat pancreatic islets in the presence of 8.3 mM glucose and at a concentration of 200 μM, which has previously been shown to be effective for (2S,3R,4S)‐4‐hydroxyisoleucine.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Paracyclophanes: Extending the Bridges. Reactions
Authors: Pechlivanidis Zissis , Hopf Henning , Grunenberg Jörg , Ernst Ludger
Published: November 2008

[m.n]Paracyclophanes with bridges of equal and unequal length (m,n ≤ 4) undergo electrophilic aromatic substitution (Friedel–Crafts acylation, bromination) under very mild conditions as long as the bridge contains less than four atoms. Whenever there is a choice, the aromatic ring is attacked at the position closest to the shorter alkano bridge, which indicates that the transannular benzene moiety acts as a neighboring group. By brominating the acetyl derivatives obtained, and the acids and esters derived therefrom, a second substituent is introduced into the pseudo‐geminal position, that is, directly opposite the directing group. However, this effect is observed only for those [m.n]phanes in which the length of the neighboring bridge does not exceed three atoms. For the butano‐bridged derivatives, the regioselectivity is lost completely. Very similar results were observed for [m.n]paracyclophanes carrying two ester substituents on one benzene ring, the limiting case being the [4.3]paracyclophane derivative. We propose that the stereocontrolling effect of a substituent can only occur when the intra‐annular distance is below 4 Å. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis of N6,N6‐Dialkyladenine Nucleosides Using Hexaalkylphosphorus Triamides Produced in Situ
Authors: Lakshman Mahesh K. , Choudhury Asad , Bae Suyeal , Rochttis Eliezer , Pradhan Padmanava , Kumar Amit
Published: November 2008

Reactions between secondary amines and phosphorus trichloride (PCl3) leads to the formation of the corresponding tris(dialkylamino)phosphanes or hexaalkylphosphorus triamides [HAPTs: (R2N)3P]. Treatment of silyl‐protected 2′‐deoxyinosine and acetyl‐protected inosine with the HAPTs produced in situ, together with iodine (I2), leads to the formation of N6,N6‐dialkyladenosine and ‐2′‐deoxyadenosine. In some cases the stoichiometry of the amine is important, as is the use of a tertiary amine base. The effect of amine stoichiometry on the reaction between HAPT and I2 has been studied by 31P{1H} NMR spectroscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
FMRI correlates of visuo‐spatial reorienting investigated with an attention shifting double‐cue paradigm
Authors: Natale Elena , Marzi Carlo Alberto , Macaluso Emiliano
Published: November 2008

The control of visuo‐spatial attention entails the joint contribution of goal‐directed (endogenous) and stimulus‐driven (exogenous) factors. However, little is known about the neural bases of the interplay between these two mechanisms. To address this issue, we presented endogenous (spatially informative) and exogenous (noninformative) visual cues sequentially within the same trial (double‐cue paradigm) during fMRI, crossing factorially the validity of the two cues. We found that both endogenous and exogenous cues affected behavioral performance, speeding‐up or slowing‐down target discrimination when valid and invalid, respectively. Despite the double‐cue paradigm maximizes the interplay between endogenous and exogenous factors, the two types of cue affected responses in an independent manner without any significant effect of congruence. The imaging data revealed increased activation in separate cortical areas following invalid endogenous and invalid exogenous cues. A fronto‐parietal system was activated during invalid endogenous trials, whereas a region at the temporo‐occipital junction was activated during invalid exogenous trials. Within both circuits, activity was unaffected by the validity of the other cue. These results indicate the existence of separate, noninteracting neural circuits for endogenous and exogenous reorienting of visuo‐spatial attention. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Exploring the social value of health‐care interventions: a stated preference discrete choice experiment
Authors: Green Colin , Gerard Karen
Published: November 2008

Much of the literature on distributive preferences covers specific considerations in isolation, and recent reviews have suggested that research is required to inform on the relative importance of various key considerations. Responding to this research recommendation, we explore the distributive preferences of the general public using a set of generic social value judgments. We report on a discrete choice experiment (DCE) survey, using face‐to‐face interviews, in a sample of the general population (n=259). The context for the survey was resource allocation decisions in the UK National Health Service, using the process of health technology appraisal as an example. The attributes used covered health improvement, value for money, severity of health, and availability of other treatments, and it is the first such survey to use cost‐effectiveness in scenarios described to the general public. Results support the feasibility and acceptability of the DCE approach for the elicitation of public preferences. Choice data are used to consider the relative importance of changes across attribute levels, and to model utility scores and relative probabilities for the full set of combinations of attributes and levels in the experimental design used (n=64). Results allow the relative social value of health technology scenarios to be explored. Findings add to a sparse literature on ‘social’ preferences, and show that DCE data can be used to consider the strength of preference over alternative scenarios in a priority‐setting context. Copyright © 2008 John Wiley & Sons, Ltd.
Typical aromatic noncovalent interactions in proteins: A theoretical study using phenylalanine
Authors: Suresh Cherumuttathu H. , Mohan Neetha , Vijayalakshmi K. Periya , George Renjumon , Mathew Janice M.
Published: November 2008

A systematic study of CH···π, OH···π, NH···π, and cation···π interactions has been done using complexes of phenylalanine in its cationic, anionic, neutral, and zwitterionic forms with CH4, H2O, NH3, and NHat B3LYP, MP2, MPWB1K, and M06‐2X levels of theory. All noncovalent interactions are identified by the presence of bond critical points (bcps) of electron density (ρ(r)) and the values of ρ(r) showed linear relationship to the binding energies (Etotal). The estimatedEtotalfrom supermolecule, fragmentation, and ρ(r) approaches suggest that cation···π interactions are in the range of 36 to 46 kcal/mol, whereas OH···π, and NH···π interactions have comparable strengths of 6 to 27 kcal/mol and CH···π interactions are the weakest (0.62–2.55 kcal/mol). Among different forms of phenylalanine, cationic form generally showed the highest noncovalent interactions at all levels of theory. Cooperativity of multiple interactions is analyzed on the basis of ρ(r) at bcps which suggests that OH···π and NH···π interactions show positive, whereas CH···π and cation···π interactions exhibit negative cooperativity with respect to the side chain hydrogen bond interactions. In general, side chain interactions are strengthened as a result of aromatic interaction. Solvation has no significant effect on the overall geometry of the complex though slight weakening of noncovalent interactions by 1–2 kcal/mol is observed. An assessment of the four levels of theory studied herein suggests that both MPWB1K and M06‐2X give better performance for noncovalent interactions. The results also support the fact that B3LYP is inadequate for the study of weak interactions. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
GPCR‐CA: A cellular automaton image approach for predicting G‐protein–coupled receptor functional classes
Authors: Xiao Xuan , Wang Pu , Chou Kuo‐Chen
Published: November 2008

Given an uncharacterized protein sequence, how can we identify whether it is a G‐protein–coupled receptor (GPCR) or not? If it is, which functional family class does it belong to? It is important to address these questions because GPCRs are among the most frequent targets of therapeutic drugs and the information thus obtained is very useful for “comparative and evolutionary pharmacology,” a technique often used for drug development. Here, we present a web‐server predictor called “GPCR‐CA,” where “CA” stands for “Cellular Automaton” (Wolfram, S. Nature 1984, 311, 419), meaning that the CA images have been utilized to reveal the pattern features hidden in piles of long and complicated protein sequences. Meanwhile, the gray‐level co‐occurrence matrix factors extracted from the CA images are used to represent the samples of proteins through their pseudo amino acid composition (Chou, K.C. Proteins 2001, 43, 246). GPCR‐CA is a two‐layer predictor: the first layer prediction engine is for identifying a query protein as GPCR on non‐GPCR; if it is a GPCR protein, the process will be automatically continued with the second‐layer prediction engine to further identify its type among the following six functional classes: (a) rhodopsin‐like, (b) secretin‐like, (c) metabotrophic/glutamate/pheromone; (d) fungal pheromone, (e) cAMP receptor, and (f) frizzled/smoothened family. The overall success rates by the predictor for the first and second layers are over 91% and 83%, respectively, that were obtained through rigorous jackknife cross‐validation tests on a new‐constructed stringent benchmark dataset in which none of proteins has ≥40% pairwise sequence identity to any other in a same subset. GPCR‐CA is freely accessible at http://218.65.61.89:8080/bioinfo/GPCR‐CA, by which one can get the desired two‐layer results for a query protein sequence within about 20 seconds. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Accurate prediction of heats of formation by a combined method of B3LYP and neural network correction
Authors: Wu Jianming , Xu Xin
Published: November 2008

Recently, we proposed the X1 method which combines the B3LYP/6‐311+G(3df,2p)//B3LYP/6‐311+G(d,p) method with a neural network correction for an accurate yet efficient prediction of heats of formation (Wu and Xu, J Chem Phys 2007, 127, 214105). In this contribution, we discuss in detail how to set up the X1 neural network. We give examples, showing how to apply the X1 method and how the applicability of X1 can be extended. The overall mean absolute deviation of the X1 method from experiment for the 488 heats of formation is 1.52 kcal/mol compared with 9.44 kcal/mol for the original B3LYP results. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
GolP: An atomistic force‐field to describe the interaction of proteins with Au(111) surfaces in water
Authors: Iori F. , Di Felice R. , Molinari E. , Corni S.
Published: November 2008

A classical atomistic force field to describe the interaction of proteins with gold (111) surfaces in explicit water has been devised. The force field is specifically designed to be easily usable in most common bio‐oriented molecular dynamics codes, such as GROMACS and NAMD. Its parametrization is based on quantum mechanical (density functional theory [DFT] and second order Möller‐Plesset perturbation theory [MP2]) calculations and experimental data on the adsorption of small molecules on gold. In particular, a systematic DFT survey of the interaction between Au(111) and the natural amino acid side chains has been performed to single out chemisorption effects. Van der Waals parameters have been instead fitted to experimental desorption energy data of linear alkanes and were also studied via MP2 calculations. Finally, gold polarization (image charge effects) is taken into account by a recently proposed procedure (Iori, F.; Corni, S. J Comp Chem 2008, 29, 1656). Preliminary validation results of GolP on an independent test set of small molecules show the good performances of the force field. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Insights into the mechanism of methionine oxidation catalyzed by metal (Cu2+, Zn2+, and Fe3+)—Amyloid beta (Aβ) peptide complexes: A computational study
Authors: Barman Arghya , Taves Woody , Prabhakar Rajeev
Published: November 2008

In this DFT study, a mechanism of the oxidation of methionine (Met) amino acid residue catalyzed by the metal (Cu2+, Zn2+, and Fe3+) bound amyloid beta (Aβ) peptide has been proposed. Based on experimental information, two different mechanisms: (1) stepwise and (2) concerted mechanisms for this important process have been investigated. The B3LYP calculations suggest that in the stepwise mechanism, the two separate pathways leading to the same sulfoxide product [Met(O)] go through prohibitively high barriers of 27.3 and 35.1 kcal/mol, therefore it is ruled out. In the concerted mechanism, the Cu2+‐Aβ complex has been found to be the most efficient catalyst with the computed barrier of 14.3 kcal/mol. The substitutions of Cu2+ by Zn2+ and Fe3+ increase barriers to 19.6 and 16.9 kcal/mol, respectively and make the reaction thermodynamically less favorable. It was also found that, in comparison with the cysteine (Cys) residue, Met is more susceptible toward oxidation. Its substitution with Cys slightly increased the barrier to 15.8 kcal/mol for the Cu2+‐Aβ complex. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Gallbladder wall thickening in patients with acute hepatitis
Authors: Suk Ki Tae , Kim Chul Han , Baik Soon Koo , Kim Moon Young , Park Dong Hun , Kim Kyu Hong , Kim Jae Woo , Kim Hyun Soo , Kwon Sang Ok , Lee Dong Ki , Han Kwang Hyup , Um Soon Ho
Published: November 2008

Background.

Gallbladder wall thickening (GWT) is often observed in patients with acute hepatitis (AH). However, little is known regarding the relationship between AH and GWT. We analyzed the characteristics of GWT in patients with AH.

Method.

Between April 2002 and April 2007, 232 patients with AH underwent a sonographic examination. The clinical and laboratory findings of patients with GWT were evaluated and compared with patients without GWT. Data were recorded for the following variables: gender, age, laboratory findings, duration of symptom, presence of gallstone, and etiology of GWT.

Results.

A total of 147 (63%) patients with AH had GWT. GWT in patients with an alanine aminotransferase level more than 500 IU/l (5.2 ± 3.4 mm) was greater than that in other patients (3.9 ± 2.3 mm; p < 0.05). Hepatitis A virus infection (odds ratio = 3.17 [1.42–7.09]), female gender (odds ratio = 2.47 [1.34–4.56]), and an elevated total bilirubin level (odds ratio = 1.09 [1.03–1.15]) were positively associated with GWT.

Conclusion.

The incidence of GWT in patients with AH was 63%, and there was an association with hepatitis A virus infection, female gender, and an elevated total bilirubin level. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Understanding leadership skills of hospice executives
Authors: Longenecker Paul
Published: November 2008

The healthcare industry is a rapidly changing environment requiring leaders to possess a high level of leadership skills. Leaders in the hospice industry have experienced the same level of change, but over the brief span of 25 years. With the aging of hospice executives and the dynamic environment of the hospice industry, the need for strong leadership is more important than ever. This research study reports on the perceived leadership skills of hospice executives and is a replication of an earlier study (Longenecker, 2006). All study participants were executives of organizations that participated in clinical and operational benchmarking activities at the national level. The study evaluated leadership skills using transformational leadership theory as the conceptual model by which leadership skills were measured. The results of the study identified that the participants perceived they displayed an ideal use of skills based on transformational leadership theory.
Midgut pseudotumors and the maintenance of tissue homeostasis: Studies on aging and manipulated stick insects
Authors: Holtmann Matthias , Dorn August
Published: November 2008

Stick insects (Carausius morosus) develop pseudotumors in aging adults. Pseudotumor formation starts at the M2 midgut region where an accumulation of stomatogastric nerve terminals is observed. Pseudotumors arise from dying columnar cells whose basal parts form an “amorphous substance” at the basement membrane whereas the apical parts, including the nucleus, are expelled into the gut lumen. The “amorphous substance” is ensheathed by hemocytes. These nodules, which do not melanize, characterize the phenotype of the pseudotumors. With age, cell death and pseudotumor infestation increases. It is shown that the maintenance of midgut tissue homoeostasis is disturbed and becomes more serious with growing pseudotumor incidence. The increased death rate of differentiated columnar cells is no longer compensated by the proliferation of regenerative cells, i.e., intestinal stem cells, in the midgut nidi. The appearance of “holes” in the intestinal wall is evidently a causative factor of premature death. Extirpation of the hypocerebral ganglion in young adults of the stick insect (before the onset of spontaneous pseudotumor formation) provokes the apoptosis of a large number of columnar cells within 24 h and the formation of pseudotumors that are histologically identical with spontaneous ones. We conclude that the stomatogastric nervous system plays a decisive role in the regulatory mechanism maintaining midgut tissue homeostasis. The possibility of experimentally manipulating the regulatory system provides a valuable tool for the exploration of extrinsic factors involved into the feedback circuitry of tissue homeostasis. The fact that comparable pseudotumors were observed in a number of orthopteromorphan species, where they could also be induced by the interruption of the stomatogastric nervous system, indicates that its role in tissue homoeostasis may be widespread in insects and possibly represent a general principle. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.
Development of polarized female germline cysts in the polychaete, Ophryotrocha labronica
Authors: Brubacher John L. , Huebner Erwin
Published: November 2008

Polarized oogenic cysts are clonal syncytia in which cellular compartments (cystocytes) differentiate as either oocytes or nurse cells—supportive germ cells that transport material to the oocyte through cytoplasmic bridges. Although polarized cysts have evolved independently in several animal phyla, most research on this phenomenon has focused on insects, particularly Drosophila melanogaster. To provide a foundation for comparative studies of cyst polarization, we have examined the coelomic development of polarized cysts in an annelid worm, Ophryotrocha labronica, using a variety of microscopic techniques. This species has elegantly simple cysts, each consisting of two interconnected cells (one oocyte and one nurse cell) free of somatic follicular tissue. These cysts arise from segmental ovaries, but are released to the coelom early in oogenesis, where they carry out most of their development. Although the oocyte remains transcriptionally active through oogenesis, nurse cells in this species are robust biosynthetic factories, with highly polyploid nuclei, enormous nucleoli, numerous mitochondria, and abundant rough endoplasmic reticulum. Ultimately, the nurse cell dumps its cytoplasm into oocyte, detaches, and undergoes programmed cell death. Although in insects, and possibly some polychaetes, the overall polarity of the cyst is linked to the specification of future embryonic axes in the oocyte, in Ophryotrocha this appears not to be the case. Our findings provide a detailed analysis of cyst development, addressing earlier misconceptions in the literature and adding new insights. This foundation shows the potential of Ophryotrocha labronica as a model system for further experimental analysis of nurse cell–oocyte differentiation. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.
Development of the pharyngeal arch skeleton in Catostomus commersonii (Teleostei: Cypriniformes)
Authors: Engeman Jeffrey M. , Aspinwall Nevin , Mabee Paula M.
Published: November 2008

Skeletal elements of the gill arches of adult cypriniform fishes vary widely in number, size, and shape and are important characters in morphologically based phylogenetic studies. Understanding the developmental basis for this variation is thus phylogenetically significant but also important in relation to the many developmental genetic and molecularly based studies of the early developing and hence experimentally tractable gill arches in the zebrafish, a cyprinid cypriniform. We describe the sequence of the chondrification and ossification of the pharyngeal arches and associated dermal bones from Catostomus commersonii (Catostomidae, Cypriniformes) and make selected comparisons to other similarly described pharyngeal arches. We noted shared spatial trends in arch development including the formation of ventral cartilages before dorsal and anterior cartilages before posterior. Qualitatively variable gill arch elements in Cypriniformes including pharyngobranchial 1, pharyngobranchial 4, and the sublingual are the last such elements to chondrify in C. commersonii. We show that the sublingual bone in C. commersonii has two cartilaginous precursors that fuse and ossify to form the single bone in adults. This indicates homology of the sublingual in catostomids to the two sublingual bones in the adults of cobitids and balitorids. Intriguing patterns of fusion and segmentation of the cartilages in the pharyngeal arches were discovered. These include the individuation of the basihyal and anterior copula through segmentation of a single cartilage rod, fusion of cartilaginous basibranchials 4 and 5, and fusion of hypobranchial 4 with ceratobranchial 4. Such “fluidity” in cartilage patterning may be widespread in fishes and requires further comparative developmental studies. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.
Identification of disinfection by‐products of selected triazines in drinking water by LC‐Q‐ToF‐MS/MS and evaluation of their toxicity
Authors: Brix Rikke , Bahi Neus , Lopez de Alda Maria J. , Farré Marinella , Fernandez Josep‐Maria , Barceló Damià
Published: November 2008

During the development of an on‐line solid phase extraction‐liquid chromatography‐ultraviolet detection (SPE‐LC‐UV) analytical method for determination of eight selected triazines; ametryn, atrazine, cyanazine, metrybuzine, prometryn, propazin, simazine, and terbutryn, in drinking water, it was observed that the retention times of three of them (ametryn, prometryn, and terbutryn) in Milli‐Q water were different from those in chlorinated Milli‐Q water, indicating the formation of new products. The cause of this change was found in the oxidation of the molecules as a result of chlorination with sodium hypochlorite. Experiments performed at varying concentrations of triazines and hypochlorite showed that the extent of the reaction depended on their relative concentrations. At the maximum admissible level of 100 ng/l for individual pesticides in drinking water, no apparent transformation was observed in the absence or at low concentrations (0.05 mg/l) of hypochlorite; however, on increasing the concentration of hypochlorite to the level typically present in drinking water (0.9 mg/l) the transformation was complete. The reaction is quite fast; within 1 h the parent compound is completely degraded and after 22 h the concentrations of the by‐products are constant. Investigation of the by‐products by ultra performance liquid chromatography‐quadrupole‐time of flight‐ tandem mass spectrometry (UPLC‐Q‐ToF‐MS/MS) has shown that all three triazines follow a similar transformation pathway, forming four new molecules whose structure have been elucidated. The acute toxicity of the new products was investigated using a standard method based on the bioluminescence inhibition of Vibrio fischeri, and the by‐products showed a higher toxicity than that of the parent compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Peptide fragmentation induced by radicals at atmospheric pressure
Authors: Vilkov Andrey N. , Laiko Victor V. , Doroshenko Vladimir M.
Published: November 2008

A novel ion dissociation technique, which is capable of providing an efficient fragmentation of peptides at essential atmospheric pressure conditions, is developed. The fragmentation patterns observed often contain c‐type fragments that are specific to electron capture dissociation/electron transfer dissociation (ECD/ETD), along with the y‐/b‐type fragments that are specific to collision‐activated dissociation (CAD). In the presented experimental setup, ion fragmentation takes place within a flow reactor located in the atmospheric pressure region between the ion source and the mass spectrometer. According to a proposed mechanism, the fragmentation results from the interaction of ESI‐generated analyte ions with the gas‐phase radical species produced by a corona discharge source. Copyright © 2008 John Wiley & Sons, Ltd.
Mass spectrometry in newborn and metabolic screening: historical perspective and future directions
Authors: Chace Donald H.
Published: November 2008

The growth of mass spectrometry (MS) in clinical chemistry has primarily occurred in two areas: the traditional clinical chemistry areas of toxicology and therapeutic drug monitoring and more recent, human genetics and metabolism, specifically inherited disorders of intermediary metabolism and newborn screening. Capillary gas chromatography and electrospray tandem MS are the two most common applications used to detect metabolic disease in screening, diagnostics and disease monitoring of treated patients. A few drops of blood from several million newborn infants are screened annually throughout the world making this the largest application of MS in medicine. Understanding the technique, how it grew from a few dozen samples per week in the early 1990s to increasing daily volume today will provide important information for new tests that either expand newborn screening or screening in other areas of metabolism and endocrinology. There are numerous challenges to the further expansion of MS in clinical chemistry but also many new opportunities in closely related applications. The model of newborn screening and MS in medicine may be useful in developing other applications that go beyond newborns and inherited metabolic disease. As MS continues to expand in clinical chemistry, it is clear that two features will drive its success. These features are excellent selectivity and multiple analyte or profile analysis; features recognized in the 1950s and remain true today. Copyright © 2008 John Wiley & Sons, Ltd.
Design of a new multi‐turn ion optical system ‘IRIS’ for a time‐of‐flight mass spectrometer
Authors: Nishiguchi Masaru , Ueno Yoshihiro , Toyoda Michisato , Setou Mitsutoshi
Published: November 2008

A new multi‐turn ion optical system ‘IRIS’ has been designed for use with a high‐performance time‐of‐flight (TOF) mass spectrometer, which satisfies the new design concepts of time focusing and phase space stability. It has an elliptical flight path composed of four toroidal electric sectors, with a flight path length for one lap of 0.974 m. Dimensions and voltages of sector electrodes have been optimized to satisfy theoretical requirements by simulations using surface charge method. Generally, multi‐turn instruments require an injection and ejection system to inject and eject ions. On the basis of this ion optical study, we have designed an injection and ejection ion optical system, which achieves time focusing for the total system. Furthermore, we have designed novel field‐adjusting electrodes (FAEs) for the perforated sectors in the injection and ejection systems, which accurately correct the electric potential around the perforated sector's hole. We have also used simulations to evaluate mass resolving power and ion transmissions for various lap numbers or flight path lengths. Through these we have confirmed that mass resolving powers of over 100 000 can be achieved with reasonable ion transmissions for a given set of initial conditions. Usually a multi‐turn TOF mass spectrometer with a closed optic axis has mass range limitations from overtaking ions. To solve this problem, a TOF segmentation method is proposed that identifies all peaks in a TOF spectrum, including those from overtaking ions. Copyright © 2008 John Wiley & Sons, Ltd.
Synoptically forced hydroclimatology of major Arctic watersheds in general circulation models; Part 2: Eurasian watersheds
Authors: Finnis Joel , Cassano John J. , Holland Marika , Serreze Mark C. , Uotila Petteri
Published: November 2008

A synoptic climatology of daily sea level pressure patterns over Eurasia has been created and used to assess simulations of regional circulation and hydroclimatology from fourteen general circulation models (GCMs). The quality of simulated circulation varies considerably among both individual models and seasons, with summer and winter showing the best agreement with reanalysis data. Close examination of five select models reveals a tendency for GCMs to either over‐ or under‐emphasize the strength and persistence of the winter storm track over Eurasia, with an overemphasized track resulting in better agreement with reanalyses on annual time‐scales. Although pronounced, these biases have relatively little impact on the hydroclimatology of the Ob, Yenisey, and Lena watersheds. Instead, large‐scale precipitation biases appear to be primarily the result of systematic errors in simulated precipitation processes, perhaps related to relevant parameterization schemes. Finally, an effort was made to identify and characterize 20th century precipitation trends related to greenhouse gas induced climate change, by decomposing precipitation time series on the basis of variability in circulation and the mean intensity of precipitation events. Results suggest the influence of anthropogenic climate change over the past forty years is masked by natural variability. Copyright © 2008 Royal Meteorological Society
In situ Raman spectroscopic monitoring of hydroxyapatite as human mesenchymal stem cells differentiate into osteoblasts
Authors: Chiang Huihua Kenny , Peng Feng‐Ying , Hung Shih‐Chieh , Feng Ya‐Ching
Published: November 2008

The differentiation of stem cells into specific cell types is playing an essential role in the development of stem cell therapy, tissue engineering, and regenerative medicine. In this research, Raman microspectroscopy was applied to monitor the development of hydroxyapatite [HA, Ca5 (PO4)3 (OH)], which is associated with the differentiation of the human mesenchymal stem cells (hMSCs) into osteoblasts. Raman spectra exhibited dramatic changes in the HA region, 950–970 cm−1, over the period of 7–21 days after the start of differentiation. This work demonstrates the successful application of Raman spectroscopy for monitoring and quantitatively evaluating hMSC differentiation into osteoblasts. Copyright © 2008 John Wiley & Sons, Ltd.
Two‐ and three‐dimensional transition element families for adaptive refinement analysis of elasticity problems
Authors: Wu D. , Sze K. Y. , Lo S. H.
Published: November 2008

In this paper, new enhanced assumed strain (EAS) and hybrid stress transition element families are developed for 2D and 3D adaptive refinement analysis of elasticity problems. The EAS element families are based on some existing incompatible transition element families. By using the EAS method and the previous incompatible modes, the B‐matrix columns associated with the EAS modes can be directly designed such that their domain integrals vanish automatically and they can be computed more efficiently. For 2D hybrid stress transition element families, it is possible to derive different stress fields that lead to rank‐sufficient transition elements. However, the task becomes intractable for 3D hybrid stress transition elements in which many combinations of mid‐side and mid‐face nodes are possible. This paper proposes to use hybrid stress transition element families in which the assumed stress fields are linearly complete. The new 2D element family is more accurate than the 2D rank‐sufficient element family. The new 3D element family is more accurate than the one with additional bilinear stress modes. Numerical examples reveal that the most accurate transition element families are the newly developed hybrid stress families followed by the EAS families, the incompatible families and then the compatible families. Copyright © 2008 John Wiley & Sons, Ltd.
Parallel Galerkin domain decomposition procedures for parabolic equation on general domain
Authors: Ma Keying , Sun Tongjun , Yang Danping
Published: November 2008

Parallel Galerkin domain decomposition procedures for parabolic equation on general domain are given. These procedures use implicit Galerkin method in the subdomains and simple explicit flux calculation on the interdomain boundaries by integral mean method or extrapolation method to predict the inner‐boundary conditions. Thus, the parallelism can be achieved by these procedures. These procedures are conservative both in the subdomains and across interboundaries. The explicit nature of the flux prediction induces a time‐step limitation that is necessary to preserve stability, but this constraint is less severe than that for a fully explicit method. L2‐norm error estimates are derived for these procedures. Compared with the work of Dawson and Dupont [Math Comp 58 (1992), 21–35], these L2‐norm error estimates avoid the loss of H−1/2 factor. Experimental results are presented to confirm the theoretical results. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Graded Galerkin methods for the high‐order convection‐diffusion problem
Authors: Liu Song‐Tao , Xu Yuesheng
Published: November 2008

We develop a Galerkin method using the Hermite spline on an admissible graded mesh for solving the high‐order singular perturbation problem of the convection‐diffusion type. We identify a special function class to which the solution of the convection‐diffusion problem belongs and characterize the approximation order of the Hermite spline for such a function class. The approximation order is then used to establish the optimal order of uniform convergence for the Galerkin method. Numerical results are presented to confirm the theoretical estimate.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Down syndrome serum screening also identifies an increased risk for multicystic dysplastic kidney, two‐vessel cord, and hydrocele
Authors: Hoffman Jodi D. , Bianchi Diana W. , Sullivan Lisa M. , Mackinnon Brenda L. , Collins Jamie , Malone Fergal D. , Porter T. Flint , Nyberg David A. , Comstock Christine H. , Bukowski Radek , Berkowitz Richard L. , Gross Susan J. , Dugoff Lorraine , Craigo Sabrina D. , Timor‐Tritsch Ilan E. , Carr Stephen R. , Wolfe Honor M. , D'Alton Mary E.
Published: November 2008

Objective

The FASTER trial compared first and second trimester screening methods for aneuploidy. We examined relationships between maternal serum markers and common congenital anomalies in the pediatric outcome data set of 36 837 subjects.

Methods

We used nested case–control studies, with cases defined by the most common anomalies in our follow‐up database, and up to four controls matched by enrollment site, maternal age and race, enrollment gestational age, and infant gender. Serum markers were dichotomized to ≥ 2 or < 0.5 multiples of the median (MoM). Odds ratios (ORs) and 95% confidence intervals (CI) were estimated.

Results

Statistically significant (p < 0.05) associations were found between inhibin A ≥ 2 MoM with fetal multicystic dysplastic kidney (MCDK) (OR = 27.5, 95% CI: 2.8–267.7) and two‐vessel cord (OR = 4.22, 95% CI:1.6–10.9); hCG of ≥ 2 MoM with MCDK (OR = 19.56, 95% CI: 1.9–196.2) and hydrocele (OR = 2.48, 95% CI: 1.3–4.6); and PAPP‐A ≥ 2.0 MoM with hydrocele (OR = 1.88, 95% CI:1.1–3.3).

Conclusion

In this large prospective study, significant associations were found between several maternal serum markers and congenital anomalies. This suggests potential additional benefits to screening programs that are primarily designed to detect aneuploidy. Copyright © 2008 John Wiley & Sons, Ltd.
Simulation of chemical kinetics of elastomer crosslinking by organic peroxides
Authors: Likozar Blaž , Krajnc Matjaž
Published: November 2008

The chemistry of peroxide crosslinking was considered with the intention of the development of a fundamental kinetic model for the crosslinking process. The kinetics of the crosslinking of several elastomers by action of organic peroxides was studied, where dicumyl peroxide (DCP), t‐butyl peroxide (TBP), and di(2‐t‐butylperoxyisopropyl) benzene (DTBPIB) have been chosen as representative peroxides. The reaction mechanisms that have been proposed for the different steps in crosslinking chemistry were critically evaluated with the objective of developing a general description of the governing chemistry, where the mechanisms are consistent for all reaction steps in the crosslinking process. A fundamental kinetic model has been developed for the peroxide crosslinking, using population balance method that explicitly acknowledges the nature of the elastomer backbone and network, and thus reactants, intermediates and products with various reactivities. The kinetic model simulation was able to describe the complete crosslinking process including homolytic cleavage of the peroxide, beta cleavage of the oxy radical, hydrogen abstraction, addition reactions, radical coupling (crosslink formation), polymer scission and radical transfer for a wide range of compositions, and assortment of elastomers, using a single set of rate constants. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
A novel two‐component physical gel based on interaction between poly(acrylic acid) and 6‐deoxy‐6‐amino‐β‐cyclodextrin
Authors: Sun Song , Chen Xi , Liu Jing , Yan Junlin , Fang Yu
Published: November 2008

A two‐component physical organogel was produced by interactions of 6‐deoxy‐6‐amino‐β‐cyclodextrin (β‐CDNH2) and poly(acrylic acid). The microstructure and morphology of the gels were characterized by scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. It was revealed that the intermolecular hydrogen bonds between the molecules of β‐CDNH2 and the electrostatic interaction between the carboxyl groups of PAA and amino group of β‐CDNH2 were the main driving forces for the formation and maintenance of the network structures of the gel. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Effect of UV radiation and pro‐oxidant on PP biodegradability
Authors: Fechine G.J.M. , Rosa D.S. , Rezende M.E. , Demarquette N.R.
Published: November 2008

The effect of ultraviolet exposure on the biodegration of poly(propylene) without (PP) and with 0.3 (wt/wt) (PPOx) pro‐oxidant additives, produced by extrusion was studied. After UV exposure the samples were submitted to biodegradation (weight loss) in prepared soils. The samples before and after UV exposure were analyzed using differential scanning calorimetry, Fourier transform infrared spectroscopy, size exclusion chromatography, and optical microscopy. The exposure to UV radiation lead to more intense degradation of PPOx than of PP; the amount of carbonyl groups was larger for the PPOx samples than for PP, as well as the decrease in the Tm and in the molecular weight. The samples exposed to UV radiation showed some level of fragmentation after 56 days when placed in the prepared soil; the samples which were exposed to UV for 480 h presented just a small weight loss. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Wood‐thermoplastic composites manufactured using beetle‐killed spruce from Alaska
Authors: Yadama Vikram , Lowell Eini C. , Peterson Nels , Nicholls David
Published: November 2008

The primary objectives of the study were to characterize the critical properties of wood flour produced using highly deteriorated beetle‐killed spruce for wood‐plastic composite (WPC) production and evaluate important mechanical and physical properties of WPC extruded using an industry standard formulation. Chemical composition analysis indicated no significant differences in wood constituents between highly deteriorated and sound wood. Preliminary investigation with Fourier transform infrared spectroscopy (FTIR), however, indicated partial degradation or depolymerization of carbohydrate components in highly deteriorated wood compared to sound wood from green trees; effects of these changes could be seen in cell collapse and poor interaction between thermoplastic matrix and deteriorated wood fiber. Physical and mechanical properties of extruded WPCs manufactured from highly deteriorated material were comparable to WPC properties produced using pine wood flour that served as a control material. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Impact of cooling method and incoming sheet quality on final part surface quality in thick sheet paint film thermoformed parts
Authors: Fernholz Kedzie D. , Wykoff Rick
Published: November 2008

Thick sheet, “dry paint” film parts were thermoformed using different cooling methods and sheet temperatures to determine whether these two parameters had a direct effect on the surface quality of the final part. Although some thermoformers have claimed that applying chilled air after forming “dry paint” film parts improves the gloss of the parts, the data from this study showed that application of chilled air did not have an effect on either the parts' initial gloss or their gloss after time‐dependent hazing. The critical factor in maintaining surface quality in these parts was the maximum temperature reached by the “dry paint” film during heating. In addition, analysis of the data taken on the sheet prior to forming versus that taken on the part after forming demonstrated the importance of validating the surface quality of the as‐received sheet prior to conducting process versus appearance experiments. On the basis of these findings, a recommendation is made for incoming sheet surface quality levels for both process development studies and production applications. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
“Barbed nanowires” from polymers via electrospinning
Authors: Holzmeister Andreas , Greiner Andreas , Wendorff Joachim H.
Published: November 2008

Electrospinning is a highly versatile technique that allows producing fibers with diameters down to a few nanometers not only from polymers but also from metals, metal oxides, or ceramics. Fiber formation in electrospinning differs strongly from other fiber producing methods such as extrusion in that it is basically governed by self‐assembly processes induced by specific electrostatic interactions following the Earnshaw theorem of electrostatics. This allows the production of nanofibers with very peculiar shapes. Here, we report the one step fabrication of barbed nanofibers due to a particular choice of the spinning conditions. Such barbed fibers allow, among others, to control the total porosity of nanofiber nonwovens and to reduce the tendency of linear nano‐objects towards aggregation. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Effects of castor oil, glycol semi‐ester, and polymer concentration on the properties of waterborne polyurethane dispersions
Authors: Gao Chuanhua , Xu Xiaoming , Ni Jiani , Lin Weiwei , Zheng Qiang
Published: November 2008

A series of waterborne polyurethane dispersions (PUDs) were synthesized using castor oil, polypropylene glycol, toluene diisocyanate, and (2E)‐4‐(2,3‐dihydroxypropoxy)‐4‐oxobut‐2‐enoic acid [glycol semi‐ester (GSE)]. These PUDs can be crosslinked spontaneously upon drying, without extra additives or processing steps. Moreover, the rheological properties, particle size, and morphology of PUDs were examined with stress‐controlled rheometer, light scattering ultrafine particle analyzer, and transmission electron microscopy. Results reveal that the particle size of PUDs mainly depends on the concentrations of castor oil, GSE, and polymer. With the increase of GSE concentration and the decrease of castor oil and polymer concentration, the particle size decreases. This can be ascribed to the decrease of the particle size of the polymer dispersion, because of the decrease of the relative size of water layer to total particle size. Furthermore, increased amount of castor oil, GSE, and polymer concentrations results in an increased viscosity of PUDs because of the increase of effective volume for the dispersed phase. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Dynamic reaction involving surface modified waste ground rubber tire powder/polypropylene
Authors: Lee Sung Hyo , Zhang Zhen Xiu , Xu Deng , Chung David , Oh Gil Jong , Kim Jin Kuk
Published: November 2008

The surface of waste ground rubber tire (WGRT) powder has been modified with by allylamine via an ultraviolet (UV) treatment. The degree of grafting of the modified‐WRGT are confirmed by the Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy, energy dispersive X‐ray analysis, thermogravimetric analysis, and surface energy measurements. And then they incorporated into the polypropylene (PP) matrix. The effects of UV radiation time, WGRT loading, and allylamine concentration on the mechanical properties of the composites are measured. Mechanical properties are influenced as a function of UV radiation time, WGRT loading, and allylamine concentrations. The chemical interactions between grafted WGRT and PP matrix are investigated by X‐ray diffraction and FTIR. They show change of the crystallinity of the PP and the chemical reaction between WGRT and the PP. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Rheological study of aqueous dispersions of in situ gelable thermosensitive polymer nanogels
Authors: Wang Qin , Xu Huibi , Yang Xiangliang , Yang Yajiang
Published: November 2008

Thermosensitive poly(N‐isopropylacrylamide‐co‐acrylamide) nanogels with varied monomer compositions were prepared by precipitation polymerization. The aqueous dispersions of these thermosensitive nanogels (9 wt% of nanogel particles in phosphate‐buffered saline solution) exhibited in situ gelable characteristics. A steady‐state and dynamic rheological analysis demonstrated that the nanogel dispersions were typical pseudoplastic liquids at room temperature. The viscosity of the nanogel dispersions at a constant shear rate increased with an increase of the acrylamide content. When the temperature was increased to 37°C, the pseudoplastic liquid turned into an elastic solid, as the result of a sol–gel phase transition of the nanogel aqueous dispersion during the raise of the temperature. Dynamic temperature ramp circle curves suggest that the sol–gel transition was reversible but with a clear hysteresis. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers