bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel fire resistant matrixes for composites from cyclic poly(butylene terephthalate) oligomers
Authors: Tripathy Amiya R. , Farris Richard J. , MacKnight William J.
Published: September 2007

The objective of the work is to exploit the processing advantages of c‐PBT oligomers, essentially required in industrial practice to produce new, robust, multifunctional hybrid copolymers of c‐PBT oligomers in a single reaction‐molding step, which will be suitable for the use in continuous fiber composites with excellent flame retardant properties. In this article a series of copolyesters were synthesized by using in situ polymerization of cyclic poly(butylene terepthalate) oligomers (c‐PBT) and hydroxyl terminated bisphenols and hydroxylated siloxanes in the presence of a tin catalyst at a moderate temperature. The in situ copolymerization was conducted with various c‐PBT/tetrabromobisphenol A (TBBPA), bisphenol A diglycidyl ether (BPADGE) and Carbinol PDMS feed ratios respectively. The copolyesters were characterized by GPC, NMR, and DSC techniques. Pyrolysis‐combustion flow calorimeter (PCFC) and pyrolysis gas chromatography/mass spectrometry (PyGC/MS) studies were performed to characterize the fire retardant properties of the copolymers during combustion. POLYM. ENG. SCI., 47:1536–1543, 2007. © 2007 Society of Plastics Engineers
Comparative studies of ultra high molecular weight polyethylene fiber reinforced composites
Authors: Xu Tao , Farris Richard J.
Published: September 2007

Ultra high molecular weight polyethylene fiber is a very promising material for making light‐weight high strength and high impact resistant composites, especially for ballistic protective shields. Three commercially available materials designed specifically for ballistic applications are Spectra® woven cloth, Dyneema Fraglight® nonwoven felt, and Spectra Shield® Plus PCR prepreg were chosen for parallel comparisons. The high‐temperature high‐pressure sintering process was applied to all three materials. The physical, thermomechanical, and microstructural properties of the consolidated products were studied and compared, including their crystallinity, molecular orientation, impact resistance, interlaminar adhesion, flexural properties, and thermoformability. The differences in these materials and their structures are reflected in the different properties of the final products. The influence of different processing conditions on the properties also differs for each material. It is concluded that matrix free Spectra cloth composite has dominant advantages over the other two materials. POLYM. ENG. SCI., 47:1544–1553, 2007. © 2007 Society of Plastics Engineers
Influence from front contact sheet resistance on extracted diode parameters in CIGS solar cells
Authors: Malm Ulf , Edoff Marika
Published: September 2007

The extraction of one‐diode model parameters from a current–voltage (J–V) curve is problematic, since the model is one‐dimensional while real devices are indeed three‐dimensional. The parameters obtained by fitting the model curve to experimental data depend on how the current is collected, and more specifically the geometry of the contact. This is due to the non‐uniform lateral current flow in the window layers, which leads to different parts of the device experiencing different front contact voltage drop, and hence different operating points on the ideal J–V curve. In this work, finite element simulations of three‐dimensional contact structures are performed and compared to experimental data on Cu(In,Ga)Se2‐based solar cell devices. It is concluded that the lateral current flow can influence the extracted parameters from the one‐diode model significantly if the resistivity of the front contact material is high, or if there is no current collecting grid structure. These types of situations may appear in damp heat‐treated cells and module type cells, respectively. Copyright © 2007 John Wiley & Sons, Ltd.
Design and synthesis of a tribranched phenylethynyl‐terminated aryl ether compound and its use as a reactive diluent for PETI‐5
Authors: Rao Xianhua , Dang Guodong , Zhou Hongwei , Yang Wei , Cui Gang , Chen Chunhai , Yokota Rikio
Published: September 2007

In this study, a tribranched, phenylethynyl‐terminated aryl ether compound (Tri‐PE‐PAEK) was synthesized. This novel star‐shaped compound exhibits a good combination of properties, such as a low melting temperature (252 °C) and good solubility in aprotic solvents, as well as a low melt viscosity (0.1 P at 280 °C). All these advantages make it a good candidate material for modern processing techniques such as resin infusion and resin transfer molding, which are the most favorable methodologies for current economical manufacturing of polymer matrix/carbon fiber composites. Furthermore, after undergoing thermal curing to yield a network at 370 °C for 1 h, a cured sample exhibited an unexpectedly higher glass transition temperature (370 °C), storage modulus retention above the glass transition temperature, and good thermal stability. In addition, this compound can be used as a reactive diluent for phenylethynyl‐terminated imide oligomer, which has the molecular weight of 5000 g/mol (PETI‐5) to reduce its viscosity and lower the minimum temperature of the minimum viscosity. Meanwhile, the toughness of a cured blended resin can be greatly increased with the addition of just 10% Tri‐PE‐PAEK to PETI‐5. Further loading levels of Tri‐PE‐PAEK in the blending would lead to a higher storage modulus and a higher mechanical strength without compromising the thermal stability. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4844–4854, 2007
Surface interaction of well‐defined, concentrated poly(2‐hydroxyethyl methacrylate) brushes with proteins
Authors: Yoshikawa Chiaki , Goto Atsushi , Tsujii Yoshinobu , Ishizuka Norio , Nakanishi Kazuki , Fukuda Takeshi
Published: September 2007

The interaction of concentrated polymer brushes with proteins was chromatographically investigated. By the use of surface‐initiated atom transfer radical polymerization, a low‐polydispersity poly(2‐hydroxyethyl methacrylate) (PHEMA) was densely grafted onto the inner surfaces of silica monoliths with mesopores of about 50 and 80 nm in mean size. The graft density reached 0.4–0.5 chains/nm2. The 80‐nm‐mesopore monolithic column with the concentrated PHEMA brush was characterized through the elution of low‐polydispersity pullulans with different molecular weights, clearly showing two modes of size exclusion, that is, one by the mesopores and the other by the brush phase. The latter mode gave a sharp separation with a critical molecular weight (size‐exclusion limit) of about 1000. This molecular size of pullulan was comparable to the distance between the nearest‐neighbor graft points. The elution behaviors of five proteins of different sizes (bovine serum thyroglobulin, bovine serum immunoglobulin G, bovine serum albumin, horse heart myoglobin, and bovine serum aprotinin) were studied with this PHEMA‐grafted column. The smallest protein, aprotinin, with a pullulan‐reduced molecular weight slightly larger than the critical value of 1000, was eluted much behind the corresponding pullulan, and this indicated that it barely got into the brush layer, suffering from a strong affinity interaction within the brush. On the other hand, the other four larger proteins were eluted at the same elution volumes as the equivalent pullulans, and this meant that they were perfectly excluded from the brush layer and separated only in the size‐exclusion mode by the mesopores without an affinity interaction with the brush surface. This excellent inertness of the concentrated brush in the interaction with the large proteins should afford the system long‐term stability against biofouling. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4795–4803, 2007
Polymerization behaviors of racemic and chiral amphiphilic monomers in organized bilayer membranes of lamellar liquid crystalline phase
Authors: Chen Xinjiang , Matsuo Goh , Ohtani Bunsho , Tsujii Kaoru
Published: September 2007

A racemic amphiphilic monomer, n‐dodecyl glyceryl itaconate (DGI), forms bilayer membranes in water in the presence of small amount of ionic cosurfactant and shows iridescent color. A chiral DGI, S‐DGI, also shows an iridescent property, but with a rather red shift in the color, which can be ascribed to the increased packing density of the monomer in the bilayer membranes. Chrial DGI has a more compact packing density than racemic one owing to closer distance between the monomer molecules; the conversion rate, however, is slower than that of racemic one when H2O2 is used as an initiator. When the initiator is changed to an amphiphilic one, 4‐(2‐hydroxyethoxy) phenyl‐(2‐hydroxy‐2‐propyl) ketone (Irgacure 2959), the chiral DGI shows even a little faster conversion rate than that of racemic one. The NMR chemical shift results of protons in benzene ring show that the molecules of Irgacure 2959 insert into the bilayer membranes. The molecular weights of the corresponding polymers prove that the initiation by H2O2 is restricted compared to that by Irgacure 2959. It is concluded that the decelerated polymerization behavior of chiral DGI initiated by H2O2 is a result of limited diffusion of the initiator into the lamellar bilayer structures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4891–4900, 2007
Solvent effects in the slow dynamics of proteins
Authors: Hinsen Konrad , Kneller Gerald R.
Published: September 2007

The influence of solvent on the slow internal dynamics of proteins is studied by comparing molecular dynamics simulations of solvated and unsolvated lysozyme. The dynamical trajectories are projected onto the protein's normal modes in order to obtain a separate analysis for each of the associated time scales. The results show that solvent effects are important for the slowest motions (below ≈ 1 ps−1) but negligible for faster motions. The damping effects seen in the latter show that the principal source of friction in protein dynamics is not the solvent, but the protein itself. Proteins 2008. © 2007 Wiley‐Liss, Inc.
The SKE‐DOCK server and human teams based on a combined method of shape complementarity and free energy estimation
Authors: Terashi Genki , Takeda‐Shitaka Mayuko , Kanou Kazuhiko , Iwadate Mitsuo , Takaya Daisuke , Umeyama Hideaki
Published: September 2007

We participated in rounds 6–12 of the critical assessment of predicted interaction (CAPRI) contest as the SKE‐DOCK server and human teams. The SKE‐DOCK server is based on simple geometry docking and a knowledge base scoring function. The procedure is summarized in the following three steps: (1) protein docking according to shape complementarity, (2) evaluating complex models, and (3) repacking side‐chain of models. The SKE‐DOCK server did not make use of biological information. On the other hand, the human team tried various intervention approaches. In this article, we describe in detail the processes of the SKE‐DOCK server, together with results and reasons for success and failure. Good predicted models were obtained for target 25 by both the SKE‐DOCK server and human teams. When the modeled receptor proteins were superimposed on the experimental structures, the smallest Ligand‐rmsd values corresponding to the rmsd between the model and experimental structures were 3.307 and 3.324 Å, respectively. Moreover, the two teams obtained 4 and 2 acceptable models for target 25. The overall result for both the SKE‐DOCK server and human teams was medium accuracy for one (Target 25) out of nine targets. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Nanostructured thermoelectric oxides with low thermal conductivity
Authors: Weidenkaff A. , Robert R. , Aguirre M. H. , Bocher L. , Schlapbach L.
Published: September 2007

Complex metal oxides, such as e.g. perovskite‐type phases are developed as potential functional materials to improve the efficiency of thermoelectric converters. Among those, cobaltates with p‐type conductivity and n‐type manganates are considered for the realisation of a ceramic thermoelectric converter. Sintered pellets with the composition AMO3–δ (A = Ln, RE; M = Co, Mn, Ni, Ti) and “Ca3Co4O9 derivates” were synthesized and characterised concerning their thermoelectric properties in a broad temperature range. It was found that the Seebeck coefficient and the electrical conductivity do not depend on the dimensions of the crystallites, while the heat conductivity can be substantially lowered by decreasing the size of the crystalline domains in these systems. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The impact of missing data and how it is handled on the rate of false‐positive results in drug development
Authors: Barnes Sunni A. , Mallinckrodt Craig H. , Lindborg Stacy R. , Carter M. Kallin
Published: September 2007

In drug development, a common choice for the primary analysis is to assess mean changes via analysis of (co)variance with missing data imputed by carrying the last or baseline observations forward (LOCF, BOCF). These approaches assume that data are missing completely at random (MCAR). Multiple imputation (MI) and likelihood‐based repeated measures (MMRM) are less restrictive as they assume data are missing at random (MAR). Nevertheless, LOCF and BOCF remain popular, perhaps because it is thought that the bias in these methods lead to protection against falsely concluding that a drug is more effective than the control. We conducted a simulation study that compared the rate of false positive results or regulatory risk error (RRE) from BOCF, LOCF, MI, and MMRM in 32 scenarios that were generated from a 25 full factorial arrangement with data missing due to a missing not at random (MNAR) mechanism. Both BOCF and LOCF inflated RRE were compared to MI and MMRM. In 12 of the 32 scenarios, BOCF yielded inflated RRE compared with eight scenarios for LOCF, three scenarios for MI and four scenarios for MMRM. In no situation did BOCF or LOCF provide adequate control of RRE when MI and MMRM did not. Both MI and MMRM are better choices than either BOCF or LOCF for the primary analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Antiparkinson therapeutic potencies correlate with their affinities at dopamine D2High receptors
Authors: Seeman Philip
Published: September 2007

To determine whether antiparkinson dopamine agonists preferentially act on the high‐affinity or the low‐affinity states of dopamine D1 and D2 receptors, the agonist potencies were obtained by competition against [3H]SCH23390 for D1High and D1Low, and against [3H]domperidone for D2High and D2Low. N‐propylnorapomorphine and cabergoline were the most potent at D2High, with dissociation constants of 0.18 and 0.36 nM, respectively. Other agonists had D2HighKi values of 0.52 nM for quinagolide, 0.6 nM for (+)PHNO, 0.9 for bromocriptine, 1.8 nM for apomorphine, 2.4 nM for pergolide, 3 nM for quinpirole, and 6.2 nM for lergotrile. There was a clear correlation between the Ki values at D2High and their therapeutic concentrations in the plasma water, as derived from the known concentrations after correction for the fraction bound to the human plasma proteins. The data suggest that D2High is the primary and common target for the antiparkinson action of dopamine agonists. Bromocriptine, cabergoline, lergotrile, pergolide, and pramipexole had no affinity for D1High, consistent with the clinical observations that the D2‐selective bromocriptine and pramipexole elicit low levels of dyskinesia. Synapse 61:1013–1018, 2007. © 2007 Wiley‐Liss, Inc.
Effect of operational modes of a wind farm on the transient stability of nearby generators and on power oscillations: a Nordic grid study
Authors: Ullah Nayeem Rahmat , Thiringer Torbjörn
Published: September 2007

In this work, an operational mode of variable speed wind turbines to enhance the transient stability of nearby conventional generators is presented and investigated. This mode is then tested on the CIGRÉ Nordic32 test grid which is taken as a representation of the Swedish transmission network. It is found that by incorporating the suggested mode into the control of several planned wind farms in the southern part of the Swedish grid, the transient stability of nearby conventional generators can be increased compared to the base case where no wind farms were connected. It is also concluded that care has to be taken when selecting the control mode of a wind farm (constant power factor operation or voltage control operation) in a particular situation when it is connected together with a nearby conventional synchronous generator. The interaction between the operational mode of a wind farm and the overall synchronous generator control may interact with each other and could lead to a reduction of damping of power oscillations in nearby transmission lines instead of increasing the damping. Copyright © 2007 John Wiley & Sons, Ltd.
Conservation partnerships between Zoos and Aquariums, federal and state agencies, and nongovernmental organizations
Authors: Smith Kathleen N. , Shaw James H. , Bettinger Tammie , Caniglia Beth , Carter Tracy
Published: September 2007

Partnerships are essential for the success of conservation organizations as they strive to achieve the ultimate goal of restoring and preserving biodiversity. Now is a particularly crucial time to develop partnerships owing to increasing financial constraints on all organizations and the urgent need for species recovery and habitat preservation. This study identified characteristics of successful conservation partnerships between Association of Zoos and Aquariums (AZA) accredited institutions and related facilities, US and international governmental agencies, and nongovernmental organizations. One hundred and five AZA accredited zoos and aquariums or related facilities participated in the preliminary survey. Staff at 75 of those zoos and aquariums were interviewed by telephone for a follow‐up survey. Respondents were asked which characteristics most contributed to the success of their past and current conservation partnerships. Data were analyzed in two ways: descriptive statistics and principal component analysis. Descriptive statistics showed that effective leadership, clear and consistent communication, and trust between partners were the top three characteristics that led to partnership success. Ineffective leadership by those in charge, lack of clear, consistent communication between partners, and unreliable or insufficient sources of funding were the top three characteristics that inhibited partnership success. Using principal component analysis, the variables for each question on the questionnaire were reduced to a smaller subset of categories. Structure, personalities, process, and commitment were the four principal components of successful conservation partnerships. The three principal components that inhibited conservation partnerships were: communication, partnership personnel, and partner inequality. Results gained from this research are sure to increase the probability of success both for conservation partnerships that have already been established and for those that may develop in the future. Zoo Biol 26:471–486, 2007. © 2007 Wiley‐Liss, Inc.
Performance as a fish predator of largemouth bass [Micropterus salmoides (Lacepède)] invading Japanese freshwaters: a review
Authors: Takamura Kenzi
Published: September 2007

This review focuses on how predator performance of the invasive largemouth bass [Micropterus salmoides (Lacepède)] has been, or will be, formed in Japanese freshwaters. Predation impacts of largemouth bass on fish communities appear pervasive in both Japanese as well as North American freshwaters. Factors affecting performance as a piscivorous predator are (1) light intensity and water clarity, (2) oxygen depletion, (3) prey size and gape size, (4) behavioral refuge of prey, (5) weed beds as refuge for prey fish, (6) interaction with bluegill. Size and behavioral refuges requirements are so rigorous that they may have evolved only in some North American prey fish species like bluegill; therefore, most Japanese native fish species are unlikely to be equipped with such refuges. However, refuge habitats like aquatic weed beds could develop in Japanese freshwaters, allowing prey fish species to survive under predation pressure. The density, architecture, and species composition of aquatic plants may affect their suitability as refuges. Studies in Japanese waters have suggested that the presence of rich aquatic vegetation or invasive bluegill in bass‐introduced waters have suppressed the predation impact of largemouth bass on fish communities. In addition to these environmental factors, original genotypic and phenotypic traits of the introduced largemouth bass, and hybridization between different lineages of largemouth bass or with Florida bass [Micropterus floridanus (Lesueur)] may be involved in further adaptation of invasive largemouth bass to Japanese freshwaters.
Contemporary evolution meets conservation biology II: impediments to integration and application
Authors: Kinnison Michael T. , Hendry Andrew P. , Stockwell Craig A.
Published: September 2007

Conservation biology needs to be concerned not just with exogenous threats to populations, but also with the changing nature of populations themselves. In a previous review paper, we highlighted evolution in contemporary time (years to decades) as a largely overlooked aspect of population responses to environmental perturbations. We argued that these responses might affect the fate of natural, managed and exotic populations. In the present review, we discuss issues that may limit the integration of contemporary evolution into conservation biology—with the intent that recognition of these limitations may foster research, discussion and resolution. In particular, we consider (1) alternative perceptions of “evolutionary” and “ecological” time, (2) the role of contemporary evolution as an ecological process, (3) fitness as a bridge between evolution and conservation, and (4) challenges faced by conservation strategies based on gene flow estimation or manipulation. We close by highlighting some situations in which current conservation approaches and contemporary evolution may require reconciliation.
Computed Tomography for Triage of Suspected Scaphoid Fracturesw
Authors: Ty Jennifer M. , Lozano-Calderon Santiago , Ring David
Published: September 2007

The use of computed tomography (CT) to triage suspected scaphoid fractures is appealing because it is more readily available and less expensive than magnetic resonance imaging (MRI). Twenty-eight patients with suspected scaphoid fractures (defined as tenderness in the area of the scaphoid and initial scaphoid-specific radiographs interpreted as normal) were enrolled in a prospective protocol evaluating triage with CT. Twenty patients reached an endpoint consisting of either (1) identification of a fracture accounting for the patient's symptoms on CT or (2) normal radiographs 6 weeks or more from the time of injury. Only 2 of 28 patients (7%) were diagnosed with a nondisplaced fracture of the scaphoid waist. CT revealed an avulsion fracture of the distal pole of the scaphoid in two patients, nondisplaced fractures of the distal radius in six patients, and nondisplaced fractures of other carpal bones in four patients. Radiographs of the scaphoid taken 6 weeks or greater from the time of injury were interpreted as normal in the six patients with normal CT scans that completed the study. True scaphoid waist fractures are uncommon among patients with suspected scaphoid fractures. CT scans are useful for triage of suspected scaphoid waist fractures because alternative, less-troublesome fractures were identified in 43% of patients and no fractures were missed or undertreated. Immediate triage of suspected scaphoid fractures using CT in the emergency room has the potential to reduce unnecessary immobilization and diminish overall costs associated with treatment.
The Influence of a Continuum Background on Carrier Relaxation in InAs/InGaAs Quantum Dot
Authors: Rainò Gabriele , Visimberga Giuseppe , Salhi Abdelmajid , Todaro Maria T , De Vittorio Massimo , Passaseo Adriana , Cingolani Roberto , De Giorgi Milena
Published: September 2007

We have investigated the ultra-fast carrier dynamics in Molecular Beam Epitaxy (MBE)-grown InAs/InGaAs/GaAs quantum dots (QDs) emitting at 1.3 μm by time resolved photoluminescence (TRPL) upconversion measurements with a time resolution of about 200 fs. Changing the detection energies in the spectral region from the energy of the quantum dots excitonic transition up to the barrier layer absorption edge, we have found that, under high excitation intensity, the intrinsic electronic states are populated mainly by carriers directly captured from the barrier.
The Periodic Instability of Diameter of ZnO Nanowires via a Self-oscillatory Mechanism
Authors: Zhang Ye , Yan Youguo , Zhu Feng
Published: September 2007

ZnO nanowires with a periodic instability of diameter were successfully prepared by a thermal physical vapor deposition method. The morphology of ZnO nanowires was investigated by SEM. SEM shows ZnO possess periodic bead-like structure. The instability only appears when the diameter of ZnO nanowires is small. The kinetics and mechanism of Instability was discussed at length. The appearance of the instability is due to negative feed-back mechanism under certain experimental conditions (crystallization temperature, vapor supersaturation, etc).
Environmental and Genetic Variation of Soybean Tocopherol Content Under Brazilian Growing Conditions
Authors: Carrão‐Panizzi Mercedes Concórdia , Erhan Sevim Z.
Published: September 2007

Information about the chemical composition of soybean cultivars (cvs) and environmental impact on their composition is important for processors and exporters to meet the demand of niche markets. Tocopherol composition (α, β, γ, δ, and total), was analyzed in seeds of 89 Brazilian soybean cultivars grown under fertile soil in Ponta Grossa, Paraná state, Brazil, in 2001. A large range of variability was observed: for α‐tocopherol, 11 ppm (cv. Davis) to 191 ppm (cv. IPB‐T); for β‐tocopherol, 6 ppm (cv. IAC 1) to 64 ppm (cv. IPB‐T); for γ‐tocopherol, 304 ppm (BR62 Carla) to 1333 ppm (cv. Bienville); for δ‐tocopherol, 174 ppm (cv. UFV 15) to 580 ppm (cv.IAS‐5; and for total tocopherols, 561 ppm (cv. BRS62 Carla) to 1,983 ppm (cv. BR4‐RC). For comparison of different growing locations, cv. MG/BR 46 Conquista was grown in 16 different locations of the Minas Gerais and Goiás states (Central Region, ca. 17° South latitude). Higher content of total tocopherol was found in Conquista, Uberaba, Sacramento, and Cerrado, while lower contents were observed in Alvorada, Iraí, and Uberlândia. In the South region (ca. 23° South latitude), the cultivar IAS 5, grown in 12 different locations of Paraná and São Paulo states, showed high total tocopherol content in Londrina, Pedrinhas, Ponta Grossa, and Nuporanga, and lower amounts in Cascavel, Pirassununga, Luiziana, and Morro Agudo. Tocopherol content in soybean seeds varied due to genetic differences as well as to the local environmental factors of different growing locations.
Somatostatin inhibits insulin‐like growth factor‐I receptor expression in the gill of a teleost fish (Oncorhynchus mykiss)
Authors: Very Nicole M. , Sheridan Mark A.
Published: September 2007

Rainbow trout gill tissue was used to examine the role of somatostatin (SS) on insulin‐like growth factor‐I (IGF‐I) receptor expression. In vivo implantation of fish with somatostatin‐14 (SS‐14) reduced expression of IGF‐I receptor mRNAs as well as [125I]‐IGF‐I binding. In vitro incubation of gill filaments with SS‐14 or various SS isoforms, including SS‐28 and [Tyr7, Gly10]‐SS‐14‐containing peptides, directly inhibited IGF‐I receptor mRNA expression. SS‐14 also inhibited [125I]‐IGF‐I binding in vitro. These data indicate that SSs inhibit the mRNA and functional expression of IGF‐I receptors in gill, and suggest that SSs regulate growth in an extrapituitary manner by reducing sensitivity to IGF‐I.
Peptide binding proclivities of calcium loaded calbindin‐D28k
Authors: Kordys David R. , Bobay Benjamin G. , Thompson Richele J. , Venters Ronald A. , Cavanagh John
Published: September 2007

Calbindin‐D28k is known to function as a calcium‐buffering protein in the cell. Moreover, recent evidence shows that it also plays a role as a sensor. Using circular dichroism and NMR, we show that calbindin‐D28k undergoes significant conformational changes upon binding calcium, whereas only minor changes occur when binding target peptides in its Ca2+‐loaded state. NMR experiments also identify residues that undergo chemical shift changes as a result of peptide binding. The subsequent use of computational protein–protein docking protocols produce a model describing the interaction interface between calbindin‐D28k and its target peptides.
Phytanic acid: measurement of plasma concentrations by gas–liquid chromatography–mass spectrometry analysis and associations with diet and other plasma fatty acids
Authors: Allen Naomi E. , Grace Philip B. , Ginn Annette , Travis Ruth C. , Roddam Andrew W. , Appleby Paul N. , Key Timothy
Published: September 2007

Epidemiological data suggest that a diet rich in animal foods may be associated with an increased risk of several cancers, including cancers of the prostate, colorectum and breast, but the possible mechanism is unclear. It is hypothesised that phytanic acid, a C20 branched-chain fatty acid found predominantly in foods from ruminant animals, may be involved in early cancer development because it has been shown to up regulate activity of α-methylacyl-coenzyme A racemase, an enzyme commonly found to be over-expressed in tumour cells compared with normal tissue. However, little is known about the distribution of plasma phytanic acid concentrations or its dietary determinants in the general population. The primary aim of the present cross-sectional study was to determine circulating phytanic acid concentrations among ninety-six meat-eating, lacto-ovo-vegetarian and vegan women, aged 20–69 years, recruited into the Oxford component of the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford). Meat-eaters had, on average, a 6.7-fold higher geometric mean plasma phytanic acid concentration than the vegans (5·77v.0·86 μmol/l;P < 0·0001) and a 47 % higher mean concentration than the vegetarians (5·77v.3·93 μmol/l;P = 0·016). The strongest determinant of plasma phytanic acid concentration appeared to be dairy fat intake (r0·68;P < 0·0001); phytanic acid levels were not associated with age or other lifestyle factors. These data show that a diet high in fat from dairy products is associated with increased plasma phytanic acid concentration, which may play a role in cancer development.
High folic acid increases cell turnover and lowers differentiation and iron content in human HT29 colon cancer cells
Authors: Pellis Linette , Dommels Yvonne , Venema Dini , Polanen Ab van , Lips Esther , Baykus Hakan , Kok Frans , Kampman Ellen , Keijer Jaap
Published: September 2007

Folate, a water-soluble B vitamin, is a cofactor in one-carbon metabolism and is essential for DNA synthesis, amino acid interconversion, methylation and, consequently, normal cell growth. In animals with existing pre-neoplastic and neoplastic lesions, folic acid supplementation increases the tumour burden. To identify processes that are affected by increased folic acid levels, we compared HT29 human colon cancer cells exposed to a chronic supplemental (100 ng/ml) level of folic acid to cells exposed to a normal (10 ng/ml) level of folic acid, in the presence of vitamin B12and other micronutrients involved in the folate–methionine cycle. In addition to higher intracellular folate levels, HT29 cells at 100 ng folic acid/ml displayed faster growth and higher metabolic activity. cDNA microarray analysis indicated an effect on cell turnover and Fe metabolism. We fully confirmed these effects at the physiological level. At 100 ng/ml, cell assays showed higher proliferation and apoptosis, while gene expression analysis and a lower E-cadherin protein expression indicated decreased differentiation. These results are in agreement with the promoting effect of folic acid supplementation on established colorectal neoplasms. The lower expression of genes related to Fe metabolism at 100 ng folic acid/ml was confirmed by lower intracellular Fe levels in the cells exposed to folic acid at 100 ng/ml. This suggests an effect of folate on Fe metabolism.
Search for the cause‐effect relationship between Miocene silicic volcanism and hydrothermal activity in the unsaturated zone of Yucca Mountain, Nevada: Numerical modeling approach
Authors: Dublyansky Yuri , Polyansky Oleg
Published: September 2007

Elevated temperatures of waters that circulated through the thick unsaturated zone of Yucca Mountain and deposited secondary minerals have been explained by conductive heating of the rock mass by a magma body emplaced in association with the activity of the Timber Mountain silicic volcanic center (the “conductive heating” conceptual model). The model was evaluated by means of numerical modeling. Two‐ and three‐dimensional simulations of the conductive heat transfer, as well as three‐dimensional simulations considering convective flow of water, did not match the target temperature‐time “trajectory” established from fluid inclusion studies and radiometric dating of secondary minerals at Yucca Mountain. This result was obtained despite the fact that the modeling was nonconservative in that the initial conditions, boundary conditions, and parameters of the models were selected so that they would return higher temperatures and longer cooling times. We conclude that the “conductive heating” conceptual model does not appear to constitute a plausible explanation for the circulation in the past of thermal waters (up to 70–90°C, according to fluid inclusion data) in the vadose zone of Yucca Mountain. The finding has important implications for the safety and expected performance of the proposed high‐level nuclear waste disposal facility at Yucca Mountain.
Validation of AIRS v4 ozone profiles in the UTLS using ozonesondes from Lauder, NZ and Boulder, USA
Authors: Monahan K. P. , Pan L. L. , McDonald A. J. , Bodeker G. E. , Wei J. , George S. E. , Barnet C. D. , Maddy E.
Published: September 2007

Ozonesonde observations from Lauder (45.0°S, 169.7°E) and Boulder (39.9°N, 105.3°W) are used to examine the quality of the Atmospheric Infrared Sounder (AIRS) v4 vertical ozone profile product in the upper troposphere lower stratosphere (UTLS). At lower altitudes (∼700–200 hPa pressure range), AIRS ozone mixing ratios are larger than ozonesonde measurements, and at higher altitudes (∼100–30 hPa pressure range), AIRS ozone mixing ratios are smaller. Compared to the ozonesondes, AIRS retrieval results at Lauder have a median bias of 80% in the region 700–200 hPa, and 0 to −20% in the region 100–30 hPa. For Boulder these values are 40% and 0 to 5%, respectively. Using a tropopause adjusted vertical coordinate system, Lauder has median biases of +90 to +120% in the troposphere and 0 to +25% in the stratosphere whereas Boulder shows median biases of +45 to +70% in the troposphere and 0 to +35% in the stratosphere. Despite the bias, AIRS retrieval in the UTLS region shows a statistically significant positive correlation with the ozonesonde data, indicating that while the absolute values have a large uncertainty, the retrieval captures the variability of ozone in the UTLS region. Hence AIRS ozone is suitable for studies where the change in ozone is important rather than the absolute ozone mixing ratio. Examinations of the training data set show that the retrieval biases are likely influenced by the deficiency of the training data to represent ozone distribution during the regression step of the retrieval. Furthermore the physical retrieval adds little additional information to the final result.
Global patterns of relations between soil moisture and rainfall occurrence in ERA‐40
Authors: Lam Arien , Bierkens Marc F. P. , van den Hurk Bart J. J. M.
Published: September 2007

We use a generalized linear model to statistically analyze the probability of daily precipitation occurrence, dependent on precipitation persistence, annual cycle, and soil moisture. By applying this method to the global ERA‐40 re‐analysis data set, we reveal patterns of the precipitation occurrence variability as explained by each of the three variables and their interactions. These global patterns show: (1) known monsoon regions dominate the annual cycle component; (2) known regions of orographic uplifting dominate the persistence component; (3) the soil moisture component shows structure across all continents, but is most pronounced in the tropics and subtropics, and least pronounced in polar regions. In a surprisingly large part of the land surface, soil moisture influence on precipitation occurrence is of the same order of magnitude as the influence of the annual cycle.
Evolution of soil solution aluminum during transport along a forested boreal hillslope
Authors: Cory Neil , Laudon Hjalmar , Köhler Stephan , Seibert Jan , Bishop Kevin
Published: September 2007

Aluminum (Al) transfer from soils to surface waters is a crucial determinant of aquatic biodiversity in acidified and/or naturally acid surface waters. Defining how landscapes and acid deposition influence Al export depends on our understanding of the mobilization of Al within catchments. This paper documents the evolution of Al chemistry in water during its transport through a hillslope by using soil water chemistry combined with hydrometric data. Al levels moving laterally from upslope mineral soils were low (<0.1 mg·L−1). This is not consistent with a vertically infiltrating acidification front mobilizing Al from across the catchment. As water moves laterally downslope into the peaty soils of the riparian zone (RZ), Al increased along with organic acids and iron. The RZ in this study was thus a net source of Al to soil solution on all 9 sampling occasions where Al was measured, as well as a net source of dissolved organic carbon (DOC) on another dozen measurement occasions. The potential for Al concentrations being modified during transport through the RZ needs to be accounted for in efforts to relate acid deposition to toxic stream Al concentrations. Organic carrying capacity was in excess of Al for all samples. Only samples from the deeper mineral soils showed supersaturation; however, none of the samples showed degrees of supersaturation high enough for spontaneous mineral precipitation. A key area for further research is how the RZ can sustain a larger Al pool than upslope mineral soils when the supply of Al from these upslope soils to lateral flux is currently lower than that from the RZ. Two possibilities are either episodic downslope transport during periods of high lateral flow, or drainage‐induced changes in hydrology that transformed the RZ from an accumulator of Al to a source of Al.
Contributions to the cross shock electric field at a quasiperpendicular collisionless shock
Authors: Eastwood J. P. , Bale S. D. , Mozer F. S. , Hull A. J.
Published: September 2007

The normal electric field structure of a supercritical (Mms = 5.2), quasiperpendicular (θBn = 70°) collisionless shock is examined using Cluster four‐spacecraft observations of the terrestrial bow shock. Comparing the observed electric field with magnetic field and plasma observations, two different techniques find that the J × B/ne term in the generalized Ohm's law accounts for a majority of the large‐scale normal electric field and potential drop encountered by the ions ‐ the solar wind ion deceleration is in good empirical agreement with the observed potential drop, confirming earlier work. Large amplitude electric field fluctuations on shorter timescales, corresponding to fine scale structure, are not observed to contribute to the ion energization.
Regional climate change over eastern Amazonia caused by pasture and soybean cropland expansion
Authors: Sampaio Gilvan , Nobre Carlos , Costa Marcos Heil , Satyamurty Prakki , Soares‐Filho Britaldo Silveira , Cardoso Manoel
Published: September 2007

Field observations and numerical studies revealed that large scale deforestation in Amazonia could alter the regional climate significantly, projecting a warmer and somewhat drier post‐deforestation climate. In this study we employed the CPTEC‐INPE AGCM to assess the effects of Amazonian deforestation on the regional climate, using simulated land cover maps from a business‐as‐usual scenario of future deforestation in which the rainforest was gradually replaced by degraded pasture or by soybean cropland. The results for eastern Amazonia, where changes in land cover are expected to be larger, show increase in near‐surface air temperature, and decrease in evapotranspiration and precipitation, which occurs mainly during the dry season. The relationship between precipitation and deforestation shows an accelerating decrease of rainfall for increasing deforestation for both classes of land use conversions. Continued expansion of cropland in Amazonia is possible and may have important consequences for the sustainability of the region's remaining natural vegetation.
Global ship track distribution and radiative forcing from 1 year of AATSR data
Authors: Schreier Mathias , Mannstein Hermann , Eyring Veronika , Bovensmann Heinrich
Published: September 2007

One year of ENVISAT‐AATSR (Advanced Along Track Scanning Radiometer) satellite data is analyzed to derive a global distribution of ship tracks and their radiative forcing (RF). Ship tracks are changes in cloud reflectance, visible in satellite data, and result from the emission of aerosols and their precursors by ships into the clean marine boundary layer. An algorithm is presented that extracts scenes dominated by low clouds over the oceans that are susceptible to be affected by ship emissions. These selected cloud scenes are used to examine ship tracks on a global scale via visual analysis. The results show a high temporal variability of ship track occurrence with peak values in July. They also show a high spatial variability with peak values in the North Pacific Ocean and on the west coast of southern Africa, correlated with high ship traffic and frequent low cloud occurrence in regions of cold upwelling ocean currents. The analysis of backscattered radiation at top of the atmosphere (TOA) compared to the surrounding area reveals enhanced backscattering with values between 0 and 100 Wm−2. For particular regions on the west coast of North America, the annual mean RF due to ship tracks estimated by the changes in backscattered radiation at TOA can be up to −50 mWm−2. The global annual mean RF due to ship tracks is small (−0.4 to −0.6 mWm−2) and negligible compared to previous global model estimates on the total indirect aerosol effect and RF contributions of other ship emissions.
THEMIS observes possible cave skylights on Mars
Authors: Cushing G. E. , Titus T. N. , Wynne J. J. , Christensen P. R.
Published: September 2007

Seven possible skylight entrances into Martian caves were observed on and around the flanks of Arsia Mons by the Mars Odyssey Thermal Emission Imaging System (THEMIS). Distinct from impact craters, collapse pits or any other surface feature on Mars, these candidates appear to be deep dark holes at visible wavelengths while infrared observations show their thermal behaviors to be consistent with subsurface materials. Diameters range from 100 m to 225 m, and derived minimum depths range between 68 m and 130 m. Most candidates seem directly related to pit‐craters, and may have formed in a similar manner with overhanging ceilings that remain intact.
Surface latent heat flux and its relationship with sea surface temperature in the National Centers for Environmental Prediction Climate Forecast System simulations and retrospective forecasts
Authors: Wu Renguang , Kirtman Ben P. , Pegion Kathy
Published: September 2007

The present study evaluates surface latent heat flux (LHF) and its relationship with sea surface temperature (SST) in the NCEP Climate Forecast System (CFS) simulations and retrospective forecasts. Mean LHF in the CFS is higher than satellite estimates in the Tropics due to a dry bias in surface air humidity. The SST forced Global Forecast System simulation produces larger interannual variability of LHF compared to the CFS coupled simulation. The LHF‐SST correlation in the CFS simulation and retrospective forecasts shows large differences from observations in the eastern equatorial Indian Ocean and western‐central equatorial Pacific due to an excessive SST dependence in the sea‐air humidity difference in relation to a low bias in surface air humidity. In the eastern equatorial Indian Ocean, the CFS simulation disagrees with observations regarding the role of LHF in the development of SST anomalies during boreal summer.
Electrostatic structure around spacecraft in tenuous plasmas
Authors: Cully C. M. , Ergun R. E. , Eriksson A. I.
Published: September 2007

Most satellite‐based in situ plasma experiments are affected in some manner by the electrostatic structure surrounding the spacecraft. In order to better understand this structure, we have developed a fully three‐dimensional self‐consistent model that can accept realistic spacecraft geometry, including both thin (∼10−4 m) wires and long (∼102 m) booms, with open boundary conditions. The model uses an integral formulation incorporating boundary element, multigrid and fast multipole methods to overcome problems associated with the large range in scale sizes and inherently three‐dimensional structure. By applying the model to the Cluster spacecraft, we show that the electric potential structure is dominated by the charge on the wire booms, with the spacecraft body contributing at small distances. Consequently, the potential near the EFW (Electric Fields and Waves experiment) probes at the end of the wire booms is typically significantly above the true plasma potential. For the Cluster spacecraft, we show that this effect causes a 19% underestimation of the spacecraft potential and 13% underestimation of the ambient electric field. We further assess the electric field due to the sunward‐oriented photoelectron cloud, showing that the cloud contributes little to the observed spurious sunward field in the EFW data.
Inducible Nitric Oxide Synthase Does Not Mediate Brain Damage after Transient Focal Cerebral Ischemia in Mice
Authors: Prüss Harald , Prass Konstantin , Ghaeni Leyli , Milosevic Milan , Muselmann Claudia , Freyer Dorette , Royl Georg , Reuter Uwe , Baeva Nevena , Dirnagl Ulrich , Meisel Andreas , Priller Josef
Published: September 2007

Nitric oxide produced by the inducible nitric oxide synthase (iNOS) is believed to participate in the pathogenic events after cerebral ischemia. In this study, we examined the expression of iNOS in the brain after transient focal cerebral ischemia in mice. We detected differential expression of exons 2 and 3 of iNOS mRNA (16-fold upregulation at 24 to 72 h after middle cerebral artery occlusion, MCAO) compared with exons 6 to 8, 12 to 14, 21 to 22, and 26 to 27 (2- to 5-fold upregulation after 72 and 96 h), which would be compatible with alternative splicing. Expression levels of iNOS mRNA were too low for detection by the Northern blot analysis. Using specific antibodies, we did not detect any iNOS immunoreactivity in the mouse brain 1 to 5 days after MCAO, although we detected iNOS immunoreactivity in the lungs of mice with stroke-associated pneumonia, and in mouse and rat dura mater after lipopolysaccharide administration. In chimeric iNOS-deficient mice transplanted with wild-type bone marrow (BM) cells expressing the green fluorescent protein (GFP) or in wild-type mice transplanted with GFP+ iNOS-deficient BM cells, no expression of iNOS was detected in GFP+ leukocytes invading the ischemic brain or in resident brain cells. Moreover, both experimental groups did not show any differences in infarct size. Analysis of three different strains of iNOS-deficient mice and wild-type controls confirmed that infarct size was independent of iNOS deletion, but strongly confounded by the genetic background of mouse strains. In conclusion, our data suggest that iNOS is not a universal mediator of brain damage after cerebral ischemia.