bluuebunny/crossref_metadata_2025 huggingface dataset:
In‐Situ Formation of Silver Nanoparticles in PEI
Authors: Cotts S. , Compton J. , Kranbuehl D. , Espuche E. , David L. , Boiteux G.
Published: December 2009

Nanocomposites consisting of spherical particles of Ag were prepared using a single step in situ method whereby Ag is introduced into the dissolved polymer via dissolution as the organometallic complex Ag TFA in the same solvent as the polymer. The kinetic rate of formation of the particles is determined using WAXS and SAXS measurements. Nanoparticle formation is found to depend on reducing the solvent/polymer ratio, which leads to de‐solvating the metal complex. This destabilizes the metal precursor complex, causing it to degrade and the metal particles to phase separate by a thermodynamic driving force. The size of the nanoparticles varies with the cure temperature and the conditions affecting molecular mobility.
Using Plasma‐Activated High Performance Fibers with Nanocrystalline Structure in Producing New Reinforced Composite Materials
Authors: Kudinov Vladimir V. , Korneeva Natalia V.
Published: December 2009

A multifilament wet‐pull‐out method for estimation of physicochemical interaction between the fiber and the matrix in composite materials reinforced with high‐strength high‐modulus polyethylene fiber has been proposed. Controlled parameters are fiber capillary rise h and pull‐out force F. The method allows one to estimate the wettability and multifilament fiber impregnation with the liquid matrix and measure fiber capillary rise and the joint strength after curing process finished. The multifilament wet‐pull‐out method considers a total interaction between the matrix and filaments in a complex fiber or yarn. It is the advantage of this method in comparison with the tests of individual monofilament. The method makes it possible to model the real operating conditions of CM.
Polyethylene and Poly(propylene)/Clay Nanocomposites
Authors: Kubisova Hana , Merinska Dagmar , Svoboda Petr
Published: December 2009

Polyethylene and polypropylene nanocomposites were investigated with focus on mechanical and barrier properties. Structure was observed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Four types of nano‐filler were used: Nanofil 5, 8, 9 and 3000. In case of polyethylene nanocomposites the dispersion and intercalation was to low extent. Mechanical and barrier properties were worse compared to pure PE. In case of polypropylene with Nanofil 5, 9 and 3000 tensile strength was better compared to pure PP. Also PP with Nanofil 9 and 3000 had better barrier properties than pure PP for both O2 and CO2. This was explained by better intercalation and dispersion of the filler documented by XRD measurement and TEM observation.
Methionine restriction up‐regulates the expression of the pi class of glutathione S‐transferase partially via the extracellular signal‐regulated kinase‐activator protein‐1 signaling pathway initiated by glutathione depletion
Authors: Tsai Chia‐Wen , Lin Ai‐Hsuan , Wang Tsung‐Shing , Liu Kai‐Li , Chen Haw‐Wen , Lii Chong‐Kuei
Published: December 2009

Understanding the molecular events underlying gene regulation by amino acids has attracted increasing attention. Here, we explored whether the mechanism by which methionine restriction affects the expression of the π class of glutathione S‐transferase (GSTP) is related to oxidative stress initiated by glutathione (GSH) depletion. Rat primary hepatocytes were cultured in an L‐15‐based medium in the absence or presence of 200 μM L‐buthionine sulfoximine (BSO) or in a methionine‐restricted L‐15 medium supplemented with 20 μM L‐methionine up to 72 h. BSO and methionine restriction time‐dependently induced GSTP mRNA and protein expression in a similar pattern accompanied by a decrease in the cellular GSH level. The phosphorylation of extracellular signal‐regulated kinase (ERK), but not of c‐Jun NH2‐terminal kinase and p38, was stimulated by methionine restriction and BSO. Electromobility gel shift assay showed that the DNA‐binding activity of nuclear activator protein‐1 (AP‐1) increased in cells exposed to methionine restriction or BSO. With the ERK inhibitor FR180204, AP‐1 activation and GSTP expression were abolished. Moreover, the induction of GSTP by methionine restriction and BSO was reversed by GSH monoethyl ester and N‐acetylcysteine. Our results suggest that methionine restriction up‐regulates GSTP gene expression, which appears to be initiated by the ERK‐AP‐1 signaling pathway through GSH depletion in rat hepatocytes.
Resveratrol bioavailability and toxicity in humans
Authors: Cottart Charles‐Henry , Nivet‐Antoine Valérie , Laguillier‐Morizot Christelle , Beaudeux Jean‐Louis
Published: December 2009

Numerous data are now available on the beneficial properties of the polyphenolic compound resveratrol including its anti‐inflammatory and antitumor effects. However, few studies have been performed with resveratrol in humans, and the results of these studies appear fragmentary and sometimes contradictory due to variations in conditions of administration, protocols and methods of assessment. This review article presents the results of recent studies investigating the pharmacokinetics, bioavailability, and toxicity of resveratrol in humans. Resveratrol is well absorbed, rapidly metabolized, mainly into sulfo and glucuronides conjugates which are eliminated in urine. Resveratrol seems to be well tolerated and no marked toxicity was reported. These data are important in the context of human efficacy studies, and they provide further support for the use of resveratrol as a pharmacological drug in human medicine.
Effect of dietary fat on endocannabinoids and related mediators: Consequences on energy homeostasis, inflammation and mood
Authors: Banni Sebastiano , Di Marzo Vincenzo
Published: December 2009

Among the several known fatty acid‐derived chemical signals, the endogenous ligands of cannabinoid receptors type‐1 and ‐2, two G‐protein‐coupled receptors involved in several aspects of mammalian physiology and pathology, are perhaps those the levels of which have proven to be most sensitive to the fatty acid composition of the diet. The two most studied such ligands, known as endocannabinoids, are N‐arachidonoyl‐ethanolamine and 2‐archidonoylglycerol, and are found in tissues together with other N‐acyl‐ethanolamines and 2‐acylglycerols, not all of which activate the cannabinoid receptors, although several of them do exhibit important pharmacological effects. In this review article, we describe literature data indicating that the tissue concentrations of the endocannabinoids and related signalling molecules, and hence the activity of the respective receptors, can be modulated by modifying the fatty acid composition of the diet, and particularly its content in long chain PUFAs or in long chain PUFA precursors. We also discuss the potential impact of these diet‐induced changes of endocannabinoid tone on three of the major pathological conditions in which cannabinoid receptors have been involved, that is metabolic dysfunctions, inflammation and affective disorders.
Bioraffinerie: Wo kommen die Chemikalien her?
Authors: Kamm Birgit , Gerhardt Mirko , Leiß Sebastian
Published: December 2009

Momentan beruht die chemische Wertschöpfungskette auf Erdöl. Um es zu ersetzen, muss ein neuer Produktlinienstammbaum aus nachwachsenden Rohstoffen, insbesondere von Kohlenhydraten, aufgebaut werden. Wichtige Plattformchemikalien dieser neuen Wertschöpfungskette sind Milchsäure und Hydroxymethylfurfural.
”Den glücklichen Zufall einladen“
Authors: Remenyi Christian
Published: December 2009

Ryoji Noyori erhielt den Chemie‐Nobelpreis 2001 für seine Arbeiten zu asymmetrischen Hydrierungsreaktionen. Der Präsident der japanischen Forschungsorganisation Riken und Chemiker aus Leidenschaft sprach mit den Nachrichten aus der Chemie über Wissenschaft in Japan und die Zukunft der Katalyse.
Chemie für alle
Authors: Gründel Franziska
Published: December 2009

Welches Risiko steckt in Nanopartikeln? Wann leuchtet grünfluoreszierendes Protein? Und wie können pflanzliche Rohstoffe Erdöl ersetzen? Damit Studenten und Naturwissenschaftler lernen, Laien solche Fragen zu beantworten und sie für Wissenschaft zu begeistern, bildet die Universität Göttingen seit diesem Semester Chemiestudenten zu Wissenschaftsjournalisten aus.
Der andere Ostwald
Authors: Offermanns Heribert
Published: December 2009

Die Leistungen Walter Ostwalds stehen im Schatten seines Vaters Wilhelm. 1909, im selben Jahr in dem der Vater den Nobelpreis erhielt, startete der Automobilfreund Walter Ostwald Untersuchungen zum Autoabgaskatalysator. Doch erst seit 20 Jahren ist die Autoabgasreinigung in Deutschland obligatorisch.
Algebraic multigrid within defect correction for the linearized Euler equations
Authors: Naumovich Anna , Förster Malte , Dwight Richard
Published: December 2009

Given the continued difficulty of developing geometric multigrid methods that provide robust convergence for unstructured discretizations of compressible flow problems in aerodynamics, we turn to algebraic multigrid (AMG) as an alternative with the potential to automatically deal with arbitrary sources of stiffness on unstructured grids. We show here that AMG methods are able to solve linear problems associated with first‐order discretizations of the compressible Euler equations extremely rapidly. In order to solve the linear problems resulting from second‐order discretizations that are of practical interest, we employ AMG applied to the first‐order system within a defect correction iteration. It is demonstrated on two‐ and three‐dimensional test cases in a range of flow regimes (sub‐, trans‐ and supersonic) that the described method converges rapidly and robustly. Copyright © 2009 John Wiley & Sons, Ltd.
Rheology of LDPE‐based semiflexible fiber suspensions
Authors: Keshtkar M. , Heuzey M.‐C. , Carreau P.J.
Published: December 2009

Molten LDPE suspensions containing fibers of different flexibilities have been investigated in simple shear and small and large amplitude oscillatory shear (LAOS) flow. The suspensions exhibited viscosity and normal stress overshoots in stress growth experiments, and the magnitude and width of the overshoots became larger as the fiber flexibility increased. LAOS was used to help understanding the relationship between stress growth and fiber orientation. For all composites, the stress signal decreased with time in LAOS, and this behavior was more pronounced in the case of the more rigid fibers. The energy dissipated per LAOS cycle was evaluated for each composite, and it showed that less energy was dissipated as fiber flexibility decreased. In addition, the dissipated energy decreased with time and this has been interpreted in terms of a reduction of fiber contacts. The first normal stress difference showed a nonsinusoidal periodic response, and fast Fourier transform analysis indicated the presence of a first harmonic corresponding to the applied frequency for the fiber‐filled systems, in addition to the second harmonic observed for the neat LDPE. It resulted in asymmetrical strain‐normal force Lissajou curves for the suspensions, with this asymmetry being more pronounced in the case of the more rigid fibers. This has been attributed to a more extensive fiber orientation for the latter. POLYM. COMPOS., 31:1474–1486, 2010. © 2009 Society of Plastics Engineers
Quantitative 3D measurement of the nanostructural features that dictate mesoscale performance properties of nanocomposites
Authors: Mahboob M. , Kagarise C. , Koelling K.W. , Bechtel S.E.
Published: December 2009

Mesoscale performance properties of nanocomposites are dictated by the nanoscale structure developed in the composite during processing, combining nanoscale contributions over a mesoscale volume. In this artilce, for the first time, we present a procedure that deduces the fully 3D process‐induced nanostructural features of carbon nanofiber/polymer composites responsible for the mesoscale performance. In particular, we have developed a method for obtaining the nanofiber orientation in 3D Euclidean space from 2D projections provided by a transmission electron microscope. The 3D Euler angles we obtain are used to construct orientation tensors, the measure of nanostructure that has the most significant influence on mesoscale performance properties. Our measurement method is benchmarked by using numerically generated 3D samples to compare orientation tensor components known a priori with those generated using our procedure. A significant contribution of the procedure is its ability to produce quantitative 3D measurements of the evolution of nanostructure in space and time. The method is successfully applied to observe the effect of extensional rheology on nanofiber orientation. It is shown that orientation tensor data obtained from our experimental method accurately fits the predictions of the fiber orientation evolution equation proposed by Folgar and Tucker. POLYM. COMPOS., 31:1495–1503, 2010. © 2009 Society of Plastics Engineers
Cure shrinkage characterization of an epoxy resin system by two in situ measurement methods
Authors: Khoun Loleï , Hubert Pascal
Published: December 2009

Dimensional accuracy of composites manufacturing is a major issue for part producers, especially when tight tolerances are required. One of the main causes of dimensional variations is the resin volumetric changes during the cure. In this article, volumetric cure shrinkage of a one part epoxy system was characterized using two different methods. First, a modified rheology method was used to measure the volumetric cure shrinkage after the gel point. Second, a gravimetric method measured the shrinkage over the entire cure. A linear relationship between the volumetric cure shrinkage and the degree‐of‐cure was deduced from the results and the resin cure kinetic models. Results show a good agreement between the two techniques. POLYM. COMPOS., 31:1603–1610, 2010. © 2009 Society of Plastics Engineers
Metabolic profiling of bioactive Pancratium canariense extracts by GC‐MS
Authors: Torras‐Claveria Laura , Berkov Strahil , Jáuregui Olga , Caujapé Juli , Viladomat Francesc , Codina Carles , Bastida Jaume
Published: December 2009

Introduction – Pancratium canariense Ker Gawler is a plant species belonging to family Amaryllidaceae. Plants from this family are known to synthesise a particular type of bioactive compounds, named Amaryllidaceae alkaloids, which have shown AChE inhibitory activity.

Objective – To perform the metabolite profiling of methanolic extracts from P. canariense in order to identify bioactive compounds.

Methodology – Methanolic extracts from bulbs, leaves and fruits were separated into alkaloid‐free apolar and polar fractions, as well as alkaloid fractions, and subjected to AChE assay. Metabolite profiling of extracts and fractions of P. canariense was carried out by GC‐EI‐MS and LC‐ESI‐TOF‐MS.

Results – AChE inhibitory activities of the alkaloid fractions at a concentration of 10  µg/mL were 29.80 ± 0.91, 40.93 ± 4.60 and 58.06 ± 1.18% for the bulbs, leaves and fruits, respectively. Seventy‐six metabolites—mono‐, di‐ and trisaccharides, fatty acids, amino acids, sterols as well as several Amaryllidaceae alkaloids—were detected. Further purification of the alkaloids from the methanolic extracts resulted in the detection of 31 compounds including several potent AChE inhibitors such as habranthine and galanthamine, and the structural elucidation of 3‐O‐acetylhabranthine, a new natural compound with potential AChE inhibitory activity.

Conclusion – The described method resulted in effective integration of both GC‐EI‐MS and LC‐ESI‐TOF‐MS strategies, which permitted the identification of many metabolites, as well as the structural elucidation of new compounds with potential AChE inhibitory activity. Copyright © 2009 John Wiley & Sons, Ltd.
Influence of nanosilica particles on the cure and physical properties of an epoxy thermoset resin
Authors: Pethrick Richard A , Miller Claire , Rhoney Ian
Published: December 2009

Measurements are reported on the cure and physical properties of an epoxy resin created using a functionalised nanosilica filler. The filled bisphenol A epoxy (Nanopox A410) contained 40 wt% silica nanoparticles and was blended with two bisphenol A resins of molecular weights of 355 and 1075 g mol−1, respectively. Cure was achieved using 3,3‐diaminodiphenylsulfone. The functionality of the mixture containing the epoxy nanoparticles was determined using NMR analysis. Cure times showed a progressive decrease with increasing silica level. Dynamic mechanical thermal analysis showed a decrease in the value of the glass transition temperature (Tg) with increasing silica level. Tg was further studied using differential scanning calorimetry. The ability of the nanosilica to create a stable network structure was demonstrated by the variation of the high‐temperature modulus with silica composition. Thermomechanical analysis carried out below and above Tg showed a progressive decrease in the expansion coefficients with increasing silica level, indicating the effectiveness of the functionalised silica nanoparticles in forming a network. The network formed during cure in the nano‐modified epoxy is unable to undergo the densification possible in the pure resin material and explains the observed lowering of Tg with increasing nanosilica content. Copyright © 2009 Society of Chemical Industry
Synthesis, characterization and (electro)chemical polymerization of triphenylamine‐end‐functionalized poly(ε‐caprolactone)
Authors: Bendrea Anca‐Dana , Vacareanu Loredana , Grigoras Mircea
Published: December 2009

Triphenylamine‐based oligomers and polymers with linear, hyperbranched, star‐shaped or dendrimer architectures have been synthesized and studied due to their interesting electro‐optical properties. In many cases insoluble materials are obtained. In this study, we report the synthesis of grafted polytriphenylamine by chemical and electrochemical polymerization of triphenylamine‐end‐functionalized poly(ε‐caprolactone). Functionalized ε‐caprolactone oligomers were obtained by ring‐opening polymerization of ε‐caprolactone initiated by 4‐hydroxymethyltriphenylamine/stannous octanoate (tin 2‐ethylhexanoate). The ring‐opening polymerization of ε‐caprolactone using 4‐hydroxymethyltriphenylamine/stannous octanoate as initiating system provided ε‐caprolactone oligomers, with well‐defined molecular weights, containing a triphenylamine terminal group. Chemical and electrochemical coupling oxidation of the triphenylamine ends allowed the formulation of polyarylamines with ε‐caprolactone oligomers as grafts. Graft copolymers with an aryleneamine backbone and short poly(ε‐caprolactone) grafts were obtained by (electro)chemical oxidation of oligomers containing triphenylamine terminal groups. Copyright © 2009 Society of Chemical Industry
Managing Risk Symptom: A Method to Identify Major Risks of Serious Problem Projects in SI Environment Using Cyclic Causal Model
Authors: Ohtaka Hiroshi , Fukazawa Yoshiaki
Published: December 2009

Serious problem projects (SPPs) often occur, particularly in a system integration environment, and it is difficult to prevent them, since the relationships among phenomena that occur throughout the project life cycle are extremely complicated. Our goal is to make it easier to identify major risks by distinguishing phenomena that are sources of future SPPs from phenomena observed in actual field projects. By choosing several events whose causal relation is known to be cyclic, we constructed a causal model and clarified that it can contribute to the easier recognition of SPPs empirically, by analyzing actual SPP cases.
Sleep–wake functioning along the cancer continuum: focus group results from the Patient‐Reported Outcomes Measurement Information System (PROMIS®)
Authors: Flynn Kathryn E. , Shelby Rebecca A. , Mitchell Sandra A. , Fawzy Maria R. , Hardy N. Chantelle , Husain Aatif M. , Keefe Francis J. , Krystal Andrew D. , Porter Laura S. , Reeve Bryce B. , Weinfurt Kevin P.
Published: December 2009

Objective: Cancer and its treatments disturb sleep–wake functioning; however, there is little information available on the characteristics and consequences of sleep problems associated with cancer. As part of an effort to improve measurement of sleep–wake functioning, we explored the scope of difficulties with sleep in a diverse group of patients diagnosed with cancer.

Methods: We conducted 10 focus groups with patients recruited from the Duke University tumor registry and oncology/hematology clinics. Separate groups were held with patients scheduled to begin or currently undergoing treatment for breast, prostate, lung, colorectal, hematological, and other cancer types and with patients who were in posttreatment follow‐up. The content of the focus group discussions was transcribed and analyzed for major themes by independent coders.

Results: Participants not only reported causes of sleep disturbance common in other populations, such as pain and restless legs, but they also reported causes that may be unique to cancer populations, including abnormal dreams, anxiety about cancer diagnosis and recurrence, night sweats, and problems with sleep positioning. Many participants felt that sleep problems reduced their productivity, concentration, social interactions, and overall quality of life. Many also shared beliefs about the increased importance of sleep when fighting cancer.

Conclusions: The findings underscore the need for interventions that minimize the negative impact of cancer and its treatments on sleep. This study will inform efforts now underway to develop a patient‐reported measure of sleep–wake functioning that reflects the breadth of concepts considered important by patients with cancer. Copyright © 2009 John Wiley & Sons, Ltd.
Osmolytes modulate conformational exchange in solvent‐exposed regions of membrane proteins
Authors: Flores Jiménez Ricardo H. , Do Cao Marie‐Ange , Kim Miyeon , Cafiso David S.
Published: December 2009

Site‐directed spin labeling (SDSL) was used to investigate local structure and conformational exchange in two bacterial outer‐membrane TonB‐dependent transporters, BtuB and FecA. Protecting osmolytes, such as polyethylene glycols (PEGs) are known to modulate a substrate‐dependent conformational equilibrium in the energy coupling motif (Ton box) of BtuB. Here, we demonstrate that a segment that is N‐terminal to the Ton box in BtuB, is in conformational exchange between ordered and disordered states with or without substrate. Protecting osmolytes shift this equilibrium to favor the more ordered, folded state. However, a segment of BtuB that is C‐terminal to the Ton box that is not solvent exposed is insensitive to PEGs. Protecting osmolytes also modulate a conformational equilibrium in the Ton box of FecA, with larger molecular weight PEGs producing the largest shifts in the conformational free energy. These data indicate that solvent‐exposed regions of these transporters undergo conformational exchange and that regions of these transporters that are involved in protein–protein interactions sample multiple conformational substates. The sensitivity to solute provides an explanation for differences seen between two high‐resolution structures of BtuB, which each likely represent one conformation from a subset of states that are normally sampled by the protein. This work also illustrates how SDSL and osmolytes may be used to characterize and quantitate conformational equilibria in membrane proteins.
FiberDock: Flexible induced‐fit backbone refinement in molecular docking
Authors: Mashiach Efrat , Nussinov Ruth , Wolfson Haim J.
Published: December 2009

Upon binding, proteins undergo conformational changes. These changes often prevent rigid‐body docking methods from predicting the 3D structure of a complex from the unbound conformations of its proteins. Handling protein backbone flexibility is a major challenge for docking methodologies, as backbone flexibility adds a huge number of degrees of freedom to the search space, and therefore considerably increases the running time of docking algorithms. Normal mode analysis permits description of protein flexibility as a linear combination of discrete movements (modes). Low‐frequency modes usually describe the large‐scale conformational changes of the protein. Therefore, many docking methods model backbone flexibility by using only few modes, which have the lowest frequencies. However, studies show that due to molecular interactions, many proteins also undergo local and small‐scale conformational changes, which are described by high‐frequency normal modes. Here we present a new method, FiberDock, for docking refinement which models backbone flexibility by an unlimited number of normal modes. The method iteratively minimizes the structure of the flexible protein along the most relevant modes. The relevance of a mode is calculated according to the correlation between the chemical forces, applied on each atom, and the translation vector of each atom, according to the normal mode. The results show that the method successfully models backbone movements that occur during molecular interactions and considerably improves the accuracy and the ranking of rigid‐docking models of protein–protein complexes. A web server for the FiberDock method is available at: http://bioinfo3d.cs.tau.ac.il/FiberDock. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Effects of fungicides onin vitrospore germination and mycelial growth of the phytopathogensLeptosphaeria maculansandL. biglobosa(phoma stem canker of oilseed rape)
Authors: Eckert Maria R , Rossall Stephen , Selley Andrew , Fitt Bruce DL
Published: December 2009

BACKGROUND:Phoma stem canker, caused by the coexisting related fungal pathogensLeptosphaeria maculans(Des.) Ces. & de Not andL. biglobosaShoemaker & H Brun, is a major disease of winter oilseed rape in the UK. Annually, over 90% of UK crops receive at least one foliar application of fungicide, but little is known about the sensitivity of the more damagingL. maculansand the less damagingL. biglobosato these fungicides. The effects of flusilazole, tebuconazole and Methyl Benzimidazole Carbamate (MBC) fungicides (benomyl and carbendazim) on the germination of ascospores, conidia and germ tube growth of both species were examined. Isolates collected from different oilseed rape crops in England and Wales were assessed for their mycelial growth on fungicide‐amended medium, and ED50values were calculated.

RESULTS:Leptosphaeria maculansandL. biglobosadiffered in their sensitivity to fungicides. Conidial germination ofL. maculanswas more sensitive to these fungicides than that ofL. biglobosa. Isolates ofL. maculanshad smaller ED50values for mycelial growth for all fungicides tested than isolates ofL. biglobosa.

CONCLUSION:These results suggest that fungicide applications might affect the structure ofL. maculans/L. biglobosapopulations in UK winter oilseed rape crops. Copyright © 2009 Society of Chemical Industry
Modulus anomaly in magnesium matrix composites
Authors: Chowdhury A. S. M. F. , Mari D. , Schaller R.
Published: December 2009

Several magnesium matrix composites were investigated by means of mechanical spectroscopy. A modulus anomaly has been observed in the composites reinforced with fibers while the phenomenon does not occur with particles. This effect is attributed to bonding and debonding of fibers to the matrix, which is due to thermal stress relaxation by motion of dislocations. The modulus anomaly depends strongly on the orientation of the glide plane of the dislocations with respect to the matrix–fiber interface and on the aspect ratio of the fibers.
Localization dynamics of biexcitons and electron–hole plasmas in GaN‐based mixed crystals
Authors: Hirano Daisuke , Tayagaki Takeshi , Yamada Yoichi , Kanemitsu Yoshihiko
Published: December 2009

We report time‐resolved photoluminescence (PL) spectra in highly excited AlxGa1−xN mixed crystals under band‐to‐band excitation. The PL dynamics of excitons and biexcitons reveals that the localization of excitons begins within a few picoseconds delay time and almost all the excitons relax into the localized band‐tail states within 10 ps delay time after laser excitations. The biexciton formation time of ∼2 ps is extracted from the rise time of the PL intensities of excitons and biexcitons. These results indicate that biexcitons are formed from the free excitons and that the exciton localization, due to the potential fluctuations in the mixed crystals, reduces the exciton–exciton collisions and the formation of free biexcitons.
Combining [13C6]‐phenylisothiocyanate and the Edman degradation reaction: a possible breakthrough for absolute quantitative proteomics together with protein identification
Authors: Oe Tomoyuki , Maekawa Masamitsu , Satoh Ryo , Lee Seon Hwa , Goto Takaaki
Published: December 2009

This manuscript describes the results of a preliminary experiment performed as ‘proof of concept’ of a novel approach to absolute quantitation of proteins without the use of standard proteins. Absolute quantitation remains a challenging issue in the proteomics field. Therefore, we propose a combination of [13C6]‐phenylisothiocyanate (PITC) and the Edman degradation reaction as a possible breakthrough. [13C6]‐PITC was synthesized from [13C6]‐aniline with O,O′‐di‐2‐pyridyl thiocarbonate to prepare [13C6]‐phenylthiohydantoin (PTH)‐amino acids as internal standards. Upon the Edman degradation reaction, it has been confirmed that a model protein, bovine serum albumin (BSA), releases the N‐terminal amino acid quantitatively as PTH‐Asp. The standard curve of PTH‐Asp against [13C6]‐PTH‐Asp showed good linearity (r2 = 0.9977). BSA could be quantified as PTH‐Asp using the standard curve. In addition, the residual des‐Asp1‐BSA provided sufficient information for further protein identification. Copyright © 2009 John Wiley & Sons, Ltd.
Analysis of phenolic and triterpenoid compounds in licorice and rat plasma by high‐performance liquid chromatography diode‐array detection, time‐of‐flight mass spectrometry and quadrupole ion trap mass spectrometry
Authors: Tan Guangguo , Zhu Zhenyu , Zhang Hai , Zhao Liang , Liu Yi , Dong Xin , Lou Ziyang , Zhang Guoqing , Chai Yifeng
Published: December 2009

High‐performance liquid chromatography with diode‐array detection (HPLC/DAD), time‐of‐flight mass spectrometry (HPLC/TOFMS) and quadrupole ion trap mass spectrometry (HPLC/QITMS) were used for separation and identification of several compounds in licorice and rat plasma after oral administration of the herbal extract. Three phenolic compounds and one triterpenoid in licorice extract were unambiguously identified by comparing with the standard compounds. A formula database of known compounds in licorice was established, against which the other 42 compounds were identified effectively based on the accurate extract masses and formulae acquired by HPLC/TOFMS. In order to differentiate the isomers, tandem mass spectrometry was also used. The deduced fragmentation behaviors in QITMS were used to distinguish seven groups of isomers in licorice. By means of the three detectors, 46 compounds in licorice were identified. After oral administration of the extract, 25 compounds in rat plasma were detected and identified by comparing and contrasting the compounds measured in licorice with those in the plasma samples by HPLC/TOFMS. It is concluded that a rapid and effective method based on three analytical techniques was established, which is useful for identification of multiple compounds in licorice in vitro and in vivo. The result should be very useful for the quality control and curative mechanism study of licorice. Copyright © 2009 John Wiley & Sons, Ltd.
Non‐disturbing characterization of natural organic matter (NOM) contained in clay rock pore water by mass spectrometry using electrospray and atmospheric pressure chemical ionization modes
Authors: Huclier‐Markai Sandrine , Landesman Catherine , Rogniaux Hélène , Monteau Fabrice , Vinsot Agnes , Grambow Bernd
Published: December 2009

We have investigated the composition of the mobile natural organic matter (NOM) present in Callovo‐Oxfodian pore water using electrospray ionization mass spectrometry (ESI‐MS), atmospheric pressure chemical ionization mass spectrometry (APCI‐MS) and emission‐excitation matrix (EEM) spectroscopy. The generation of knowledge of the composition, structure and size of mobile NOM is necessary if one wants to understand the interactions of these compounds with heavy metals/radionuclides, in the context of environmental studies, and particularly how the mobility of these trace elements is affected by mobile NOM. The proposed methodology is very sensitive in unambiguously identifying the in situ composition of dissolved NOM in water even at very low NOM concentration, due to innovative non‐disturbing water sampling and ionization (ESI/APCI‐MS) techniques. It was possible to analyze a quite exhaustive inventory of the small organic compounds of clay pore water without proceeding to any chemical treatment at naturally occurring concentration levels. The structural features observed were mainly acidic compounds and fatty acids as well as aldehydes and amino acids. Copyright © 2009 John Wiley & Sons, Ltd.
Interactions between biological and abiotic pathways in the reduction of chlorinated solvents
Authors: Brown Richard A. , Mueller James G. , Seech Alan G. , Henderson James K. , Wilson John T.
Published: December 2009

While biologically mediated reductive dechlorination continues to be a significant focus of chlorinated solvent remediation, there has been an increased interest in abiotic reductive processes for the remediation of chlorinated solvents. In situ chemical reduction (ISCR) uses zero‐valent iron (ZVI)–based technologies, such as nanoscale iron and bimetallic ZVI, as well as naturally occurring reduced minerals incorporating dual‐valent iron (DVI), such as magnetite, green rust, and iron sulfides that are capable of dechlorinating solvents. A more recent area of development in ISCR has been in combining biological and abiotic processes.

There are several ways in which biological and abiotic processes can be combined. First, the interaction between the two may be “causative.” For example, the Air Force Center for Engineering and the Environment's biogeochemical reductive dechlorination (BiRD) technology combines a mulch barrier with hematite and gypsum to create an iron‐sulfide‐based reducing zone. Biodegradation under sulfate‐reducing conditions produces sulfide that combines with the hematite to form iron sulfides. As such, the BiRD technology is “causative”; the biological processes create reducing minerals. The biological generation of other reducing minerals such as magnetite, siderite, and green rust is feasible and is, with magnetite, observed in nature at some petroleum sites. A second type of interaction between abiotic and biotic processes is “synergistic.” For example, biological processes can enhance the activity of reduced metals/minerals. This is the basis of the EHC® ISCR technologies, which combine ZVI with a (slowly) degradable carbon substrate. This combination rapidly creates buffered, strongly reducing conditions, which result in more complete solvent degradation (i.e., direct mineralization). The extent and level of reducing activity commonly observed are much greater when both the carbon substrate and the ZVI are present. When the carbon substrate is expended, the reducing activity due to ZVI alone is much less. The understanding of biogeochemical processes and their impact on abiotic processes is still developing. As that understanding develops, new and improved methods will be created to enhance volatile organic compound destruction. © 2009 Wiley Periodicals, Inc.
Treatment of an explosives plume in groundwater using an organic mulch biowall
Authors: Ahmad Farrukh , Adamson David T. , Farhat Shahla K.
Published: December 2009

A field demonstration of a mulch permeable reactive barrier (PRB), or “biowall,” as an in situ treatment technology for explosives in groundwater is summarized. Organic mulch consists of insoluble carbon biopolymers that are enzymatically hydrolyzed during decomposition to release aqueous total organic carbon (TOC). The released TOC is then available for microorganisms to use as an electron donor to transform electrophilic contaminants via reductive pathways. A 100‐foot‐long and 2‐foot‐thick mulch biowall was installed at the Pueblo Chemical Army Depot in Colorado to treat a shallow groundwater plume containing hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX). To discourage groundwater flow bypassing around and under the biowall in this highly permeable formation, a hydraulic control was installed and the PRB was keyed into the bedrock. Technology performance was monitored using a monitoring well network to establish the development and extent of the downgradient treatment zone. Performance objectives of the field demonstration were: (1) greater than 90 percent removal of RDX across the PRB and the treatment zone; (2) an RDX concentration of less than 0.55 μg/L in the treatment zone; and (3) cumulative toxic intermediate concentration (nitroso intermediates of RDX, MNX, DNX, and TNX) of less than 20 percent of the upgradient RDX concentration. All performance objectives were met within seven months after installation once the system reached a pseudo‐steady state. By this point, a sustained reducing/treatment zone had been created downgradient of the mulch PRB that showed greater than 93 percent RDX removal, RDX concentrations less than 0.55 μg/L, and no accumulation of toxic intermediates. The mulch biowall implemented during this demonstration was successful at meeting performance objectives while addressing the majority of potential concerns of the technology. © 2009 Wiley Periodicals, Inc.
Laboratory validation study of new vapor‐phase‐based approach for groundwater monitoring
Authors: Adamson David T. , McHugh Thomas E. , Rysz Michal W. , Newell Charles J.
Published: December 2009

Recent improvements in field‐portable analytical equipment allow accurate on‐site measurement of VOCs present in air at concentrations of less than 0.1 parts per million volume (ppmv). The objective of this project is to determine if the use of these instruments for vapor‐phase measurements of headspace in a monitoring well can serve as a reliable and accurate method for monitoring volatile organic compound (VOC) concentrations in groundwater under equilibrium conditions. As part of a comprehensive research project investigating the utility of this proposed monitoring method, the authors have completed a laboratory validation study to identify instruments and sample‐collection methods that will provide accurate measurement of VOC concentrations in groundwater. This laboratory validation study identified two field‐portable instruments (a gas chromatograph and a photoionization detector) with sufficient sensitivity to measure VOCs in groundwater at concentrations below typical monitoring standards (i.e., 1 to 5 μg/L). The accuracy and precision of these field instruments was sufficient to satisfy typical data‐quality objectives for laboratory‐based analysis. In addition, two sample‐collection methods were identified that yield vapor‐phase samples in equilibrium with water: direct headspace sampling and passive diffusion samplers. These sample‐collection methods allow the field instruments (which measure VOC concentrations in vapor‐phase samples) to be used to measure VOC concentrations in water. After further validation of these sample‐collection methods in the field, this monitoring method will provide a simple way to obtain accurate real‐time measurements of VOC concentrations in groundwater using inexpensive field‐portable analytical instruments. © 2009 Wiley Periodicals, Inc.
Real longitudinal data analysis for real people: Building a good enough mixed model
Authors: Cheng Jing , Edwards Lloyd J. , Maldonado‐Molina Mildred M. , Komro Kelli A. , Muller Keith E.
Published: December 2009

Mixed effects models have become very popular, especially for the analysis of longitudinal data. One challenge is how to build a good enough mixed effects model. In this paper, we suggest a systematic strategy for addressing this challenge and introduce easily implemented practical advice to build mixed effects models. A general discussion of the scientific strategies motivates the recommended five‐step procedure for model fitting. The need to model both the mean structure (the fixed effects) and the covariance structure (the random effects and residual error) creates the fundamental flexibility and complexity. Some very practical recommendations help to conquer the complexity. Centering, scaling, and full‐rank coding of all the predictor variables radically improve the chances of convergence, computing speed, and numerical accuracy. Applying computational and assumption diagnostics from univariate linear models to mixed model data greatly helps to detect and solve the related computational problems. Applying computational and assumption diagnostics from the univariate linear models to the mixed model data can radically improve the chances of convergence, computing speed, and numerical accuracy. The approach helps to fit more general covariance models, a crucial step in selecting a credible covariance model needed for defensible inference. A detailed demonstration of the recommended strategy is based on data from a published study of a randomized trial of a multicomponent intervention to prevent young adolescents' alcohol use. The discussion highlights a need for additional covariance and inference tools for mixed models. The discussion also highlights the need for improving how scientists and statisticians teach and review the process of finding a good enough mixed model. Copyright © 2009 John Wiley & Sons, Ltd.
Successful Clinical Implementation of Corneal Epithelial Stem Cell Therapy for Treatment of Unilateral Limbal Stem Cell Deficiency
Authors: Kolli Sai , Ahmad Sajjad , Lako Majlinda , Figueiredo Francisco
Published: December 2009

The corneal epithelium is maintained by a population of stem cells known as limbal stem cells (LSCs) due to their location in the basal layer of the outer border of the cornea known as the limbus. Treatment of limbal stem cell deficiency (LSCD) has been achieved with transplantation of ex vivo expanded LSCs taken from a small biopsy of limbus. This is a relatively new technique, and as such, specific national or international guidance has yet to be established. Because of the lack of such specific guidance, our group has sought to minimize any risk to the patient by adopting certain modifications to the research methodologies in use at present. These include the replacement of all non-human animal products from the culture system and the production of all reagents and cultures under Good Manufacturing Practice conditions. In addition, for the first time, a strictly defined uniform group of patients with total unilateral LSCD and no other significant ocular conditions has been used to allow the success or failure of treating LSCD to be attributable directly to the proposed stem cell therapy. A prospectively designed study with strict inclusion and exclusion criteria was used to enroll patients from our database of patients with unilateral LSCD. Eight eyes of eight consecutive patients with unilateral total LSCD treated with ex vivo expanded autologous LSC transplant on human amniotic membrane (HAM) with a mean follow-up of 19 (RANGE) months were included in the study. Postoperatively, satisfactory ocular surface reconstruction with a stable corneal epithelium was obtained in all eyes (100%). At last examination, best corrected visual acuity improved in five eyes and remained unchanged in three eyes. Vision impairment and pain scores improved in all patients (p < .05). This study demonstrates that transplantation of autologous limbal epithelial stem cells cultured on HAM without the use of non-human animal cells or products is a safe and effective method of reconstructing the corneal surface and restoring useful vision in patients with unilateral total LSCD.
Early life stage and genetic toxicity of stannous chloride on zebrafish embryos and adults: Toxic effects of tin on zebrafish
Authors: Şişman Turgay
Published: December 2009

Humans are exposed to stannous chloride (SnCl2), known as tin chloride, present in packaged food, soft drinks, biocides, dentifrices, etc. Health effects in children exposed to tin and tin compounds have not been investigated yet. Therefore, we evaluated the possible teratogenic effects and genotoxic of SnCl2 in zebrafish (Danio rerio) adults and their embryos. In the embryo–larval study, SnCl2 showed embryo toxicity and developmental delay after exposure to the various concentrations of 10–250 μM for 120 h. Teratogenic effects including morphological malformations of the embryos and larvae were observed. The embryos exposed to 100 μM displayed tail deformation at 28 hpf and the larvae exposed to 50 μM showed reduced body growth, smaller head and eyes, bent trunk, mild pericardial edema, and smaller caudal fin at 96 hpf. The results of the teratological study show that SnCl2 induced a significant decrease in the number of living embryos and larvae. Regarding the chromosome analysis, SnCl2 induced a dose‐dependent increase in the micronucleus (MN) frequency in peripheral erythrocytes of adult zebrafish. In blood cells, the 25 μM dose of SnCl2 caused a nonsignificant increase in the total chromosomal aberrations, but the high doses significantly increased the total number of chromosomal aberrations compared with the control groups. Overall, the results clearly indicate that SnCl2 is teratogenic and genotoxic to zebrafish. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2011.
Assessment of severity of acute pancreatitis according to new prognostic factors and CT grading
Authors: Takeda Kazunori , Yokoe Masamichi , Takada Tadahiro , Kataoka Keisho , Yoshida Masahiro , Gabata Toshifumi , Hirota Masahiko , Mayumi Toshihiko , Kadoya Masumi , Yamanouchi Eigoro , Hattori Takayuki , Sekimoto Miho , Amano Hodaka , Wada Keita , Kimura Yasutoshi , Kiriyama Seiki , Arata Shinju , Takeyama Yoshifumi , Hirota Morihisa , Hirata Koichi , Shimosegawa Tooru
Published: December 2009

The assessment of severity at the initial medical examination plays an important role in introducing adequate early treatment and the transfer of patients to a medical facility that can cope with severe acute pancreatitis. Under these circumstances, “criteria for severity assessment” have been prepared in various countries, including Japan, and these criteria are now being evaluated. The criteria for severity assessment of acute pancreatitis in Japan were determined in 1990 (of which a partial revision was made in 1999). In 2008, an overall revision was made and the new Japanese criteria for severity assessment of acute pancreatitis were prepared. In the new criteria for severity assessment, the diagnosis of severe acute pancreatitis can be made according to 9 prognostic factors and/or the computed tomography (CT) grades based on contrast‐enhanced CT. Patients with severe acute pancreatitis are expected to be transferred to a specialist medical center or to an intensive care unit to receive adequate treatment there. In Japan, severe acute pancreatitis is recognized as being a specified intractable disease on the basis of these criteria, so medical expenses associated with severe acute pancreatitis are covered by Government payment.