bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aib and Iva in the Biosphere: Neither Rare nor Necessarily Extraterrestrial
Authors: Brückner Hans , Becker Dieter , Gams Walter , Degenkolb Thomas 
Published: January 2009

Abstractmagnified imageFourty‐nine species and strains of filamentous fungi of the genera Acremonium, Bionectria, Clonostachys, Emericellopsis, Hypocrea/Trichoderma, Lecythophora, Monocillium, Nectriopsis, Niesslia, Tolypocladium, and Wardomyces, deposited with the culture collection of the Centraalbureau voor Schimmelcultures (CBS) in Utrecht, The Netherlands, were grown on nutrient agar plates. Organic extracts of mycelia were analyzed after acidic total hydrolysis and derivatization by GC/SIM‐MS on Chirasil‐L‐Val for the presence of Aib (=α‐aminoisobutyric acid, 2‐methylalanine) and dl‐Iva (=isovaline, 2‐ethylalanine). In 37 of the hydrolysates, Aib was detected, and in several of them D‐Iva or mixtures of D‐ and L‐Iva. Non‐proteinogenic Aib, in particular, is a highly specific marker for a distinctive group of fungal polypeptides named peptaibols or, comprehensively, peptaibiotics, i.e., peptides containing Aib and displaying (anti)biotic activities. The biotic synthesis of these amino acids by filamentous fungi contradicts the still widespread belief that α,α‐dialkyl‐α‐amino acids do not or rarely occur in the biosphere and, if detected, are of extraterrestrial origin. The abundant production of peptaibiotics by cosmopolitan species of microfungi has also to be considered in the discussion on the occurrence of Aib and Iva in ancient and recent sediments. The detection of trace amounts of Aib in ice samples of Antarctica that are devoid of meteorites might also be related to the presence of Aib‐producing microorganisms, being either indigenous psychrophiles, or being transported and localized by mechanisms related to bioaerosols and cryoconites. The presence of microfungi being capable of producing α,α‐dialkyl α‐amino acids in terrestrial samples, and possible contamination of extraterrestrial materials are pointed out to be of relevance for the reliable interpretation of cosmogeochemical data.
Conclusions Drawn from the Buncefield and Naples Incidents Regarding the Utilization of Consequence Models
Authors: Hailwood M. , Gawlowski M. , Schalau B. , Schönbucher A. 
Published: January 2009

AbstractIn both incidents, as a result of overfilling, a very large mass of winter gasoline (mf = 300 t in Buncefield, mf = 700 t in Naples) was released, which in both cases led to a major fire of several days duration and involved 22 of a total of 41 tanks (Buncefield) and 24 of a total of 31 tanks (Naples). Whilst the Buncefield site was unconfined or only slightly confined, the Naples site had a high degree of confinement due to walls, buildings as well as a high embankment. The most important, current consequence models as well as new consequence models for the prediction of the extraordinarily high flame heights, extraordinarily high thermal radiation as well as the extraordinarily high maximum peak overpressure are described and discussed. The analysis of the Buncefield incident so far has shown that the maximum visible relative flame height lies in the region of 2.5 < (H/d)max,Bunc < 6.5 and the predicted value lies in the region 1.8 < (H/d)max,calc < 1.9. For large, black smoky fires the estimation of the critical thermal separation distance is not dependent on the total fire, but on the height of a hot, clear burning zone. In addition, for multiple tank fires there is a considerable increase in the mass burning rate, the flame height, the surface emission power as well as the thermal separation distance. With the new consequence models maximum peak overpressures for an unconfined vapor cloud explosion (UVCE) of ≈ 1.3 bar (Buncefield) and of ≈ 1.5 bar (Naples) are predicted. For a partially confined vapor cloud explosion (VCE) a maximum peak overpressure of ≈ 3 bar for a jet ignition into a corridor is predicted.
Experimental and theoretical studies on high pressure safety valves: sizing and design supported by numerical calculations (CFD)
Authors: Schmidt J. , Peschel W. , Beune A. 
Published: January 2009

AbstractHigh‐pressure safety valves with set pressures of more than 200 bar are required in industry, e.g. for polyethylene and synthesis gas applications. They are presently sized according to ISO 4126‐1. Only equations for ideal gases are presented there, and there are no indications as to how the real gas factor and the adiabatic exponent for real gases are to be calculated. For this reason, an equation for the critical mass flow rate of a real gas through a nozzle was derived and compared with the model according to EN‐ISO 4126‐1 and with experimental data. It is recommended that the current ISO‐standard be supplemented by the nozzle flow model for real gases. The first numerical calculations (ANSYS‐CFX) show that the discharge coefficient for a high pressure safety valve measured at moderate pressures can be extrapolated to very high pressures if it is used in conjunction with the nozzle flow model for real gases. However, this numerical result must yet be validated for further valve types by experiment. For this purpose, BASF has set up a high pressure valve test facility in Ludwigshafen.
Influence of the Liquid Phase Physical Properties on the Void Fraction at the Inlet of a Full‐Lift Safety Valve
Authors: Moncalvo D. , Friedel L. 
Published: January 2009

AbstractThis work studies the influence of the physical properties of a liquid on the void fraction at the inlet of a corner valve resembling a full‐lift safety valve. The test media are mixtures of air and aqueous solutions of glycerin. Our own measurements evince a reduction in the void fraction when the relative weight of glycerin in the solution is increased. If the effects of density, viscosity, and surface tension on the void fraction are accounted for by increasing the relative weight of glycerin in the solution, it results that the observed reduction of the void fraction is primarily a consequence of the enhancement of viscosity. On the other hand, the increment of the liquid density is responsible for a modest increase in the void fraction and the effect of the reduction in the surface tension is almost negligible. The enhancement of either the density or the viscosity of the liquid phase increases the relative velocity of the gas in the two‐phase mixture and, therefore, the slip. The impact of the liquid properties on the void fraction in co‐current vertical pipe flows is similar to that at the inlet of the corner valve. Among the most common correlations for pipe flows, the formulation of Rouhani and the homogeneous void fraction accurately reproduce the void fraction at the inlet of the valve only for two‐phase flows with liquids of low viscosity. A new void fraction correlation is proposed here, which reproduces all measurements very well and correctly predicts the impact of the liquid phase properties. Despite numerical coefficients, which can be fitted to additional sets of measurements, the structure of the new correlation is also applicable outside the range of two‐phase flows for which it has been explicitly validated.
Divergent Electronic Structures of Isoelectronic Metalloclusters: Tungsten(II) Halides and Rhenium(III) Chalcogenide Halides
Authors: Gray Thomas G. 
Published: January 2009

AbstractSame but different: DFT calculations on hexanuclear tungsten(II) halide clusters [W6X8X′6]2− (X, X′=Cl, Br, I) indicate a breakdown in the isoelectronic analogy between themselves and the isostructural rhenium(III) chalcogenide clusters [Re6S8X6]4− (see figure).magnified imageThe hexanuclear tungsten(II) halide clusters and the sulfido‐halide clusters of rhenium(III) are subsets of a broad system of 24‐electron metal–metal bonded assemblies that share a common structure. Tungsten(II) halide clusters and rhenium(III) sulfide clusters luminesce from triplet excited states upon ultraviolet or visible excitation; emission from both cluster series has been extensively characterized elsewhere. Reported here are density‐functional theory studies of the nine permutations of [W6X8X′6]2− (X, X′=Cl, Br, I). Ground‐state properties including geometries, harmonic vibrational frequencies, and orbital energy‐level diagrams, have been calculated. Comparison is made to the sulfide clusters of rhenium(III), of which [Re6S8Cl6]4− is representative. [W6X8X′6]2− and [Re6S8Cl6]4− possess disparate electronic structures owing to the greater covalency of the metal–sulfur bond and hence of the [Re6S8]2+ core. Low‐lying virtual orbitals are raised in energy in [Re6S8Cl6]4− with the result that the LUMO+7 (or LUMO+8 in some cases) of tungsten(II) halide clusters is the LUMO of [Re6S8Cl6]4− species. An inversion of the HOMO and HOMO−1 between the two cluster series also occurs. Time‐dependent density‐functional calculations using asymptotically correct functionals do not recapture the experimentally observed periodic trend in [W6X14]2− luminescence (Eem increasing in the order [W6Cl14]2− < [W6Br14]2− < [W6I14]2−), predicting instead that emission energies decrease with incorporation of the heavier halides. This circumstance is either a gross failure of the time‐dependent formalism of DFT or it indicates extensive multistate emission in [W6X8X′6]2− clusters. The inapplicability of isoelectronic analogies between clusters of Group 6 and Group 7 is emphasized.
Reactivity of Thiosemicarbazides with Redox Active Metal Ions: Controlled Formation of Coordination Complexes versus Heterocyclic Compounds
Authors: López‐Torres Elena , Dilworth Jonathan R. 
Published: January 2009

AbstractCareful metal selection: Control of the reaction conditions of CuII and SnIV with Me2NNHCSNHPh permits the selective synthesis of metal complexes or a range of heterocyclic compounds generated by the oxidative coupling of two thiosemicarbazides (see figure).magnified imageThe reactions of 1,1‐dimethyl‐4‐phenylthiosemicarbazide (LH) with CuII and SnIV have been investigated. If THF or methanol is used as solvent with CuII, oxidative cyclisation and coupling are observed, yielding a 1,2,4‐thiadiazole or a 1,3,4‐thiadiazolium salt. SnI4 is also able to induce oxidative coupling of two thiosemicarbazide ligands, yielding 1,2,4‐thiadiazolium or 1,2,4‐triazolium salts, with I3− as the counterion, depending on the reaction conditions. By contrast, reaction of LH with SnI4 in acetone yields a 1,3‐thiazolium salt, with I− as counterion. Reaction with CuII salts or SnI4 in basic media leads to the formation of metal complexes containing two deprotonated thiosemicarbazide ligands. In the reaction of CuCl2 in water in the presence of acid a complex containing two neutral ligands is obtained. Reactions with SnCl4 are not able to induce ligand cyclisation, although a coordination compound with two neutral ligands was isolated from methanol.
A Versatile Methodology for the Synthesis of α,β‐Unsaturated 3‐Iminophosphines
Authors: Shaffer Andrew R. , Schmidt Joseph A. R. 
Published: January 2009

AbstractPhorteen phine phosphines: Fourteen new α,β‐unsaturated β‐chloroimines were synthesized from inexpensive ketones by using the Vilsmeier–Haack reagent followed by Schiff‐base condensation. Each imine was subsequently converted to an α,β‐unsaturated 3‐iminophosphine through either late‐metal‐catalyzed phosphorus–carbon cross‐coupling or through an addition–elimination sequence (see scheme). This high‐yield protocol serves as a general means to produce α,β‐unsaturated 3‐iminophosphines.magnified imageFourteen new α,β‐unsaturated β‐chloroimines were synthesized from commercially available ketones using the Vilsmeier–Haack reagent, followed by Schiff‐base condensation. Each imine was subsequently converted to an α,β‐unsaturated 3‐iminophosphine through either late‐metal‐catalyzed phosphorus–carbon cross‐coupling or through an addition–elimination sequence. Depending on the substituents present on the vinyl group, the resultant phosphines were isolated as either E or Z diastereomers with successful isolation of predominately single diastereomers for all fourteen new phosphines investigated. Full synthetic and spectroscopic details, as well as several X‐ray crystal structures of these new imines and phosphines, are reported in addition to X‐ray crystal structures of related palladium complexes.
A Binuclear CuII Metallacycle Capable of Discerning between Pyrazine and Its Different Methyl‐Substituted Derivatives Based on Reversible Intracage Metal–Ligand Binding
Authors: Hou Gui‐Ge , Ma Jian‐Ping , Sun Ting , Dong Yu‐Bin , Huang Ru‐Qi 
Published: January 2009

AbstractSquashy cage: A flexible, spongelike, and reversible metal‐binding Cu2L2 cage that can adjust its internal space in response to pyrazine and its derivatives based on a recognition sequence of pyrazine, 2,5‐dimethylpyrazine, and 2‐methylpyrazine (see figure) is described.magnified image
Environmentally Benign Production of Biodiesel Using Heterogeneous Catalysts
Authors: Hara Michikazu 
Published: January 2009

AbstractFuelling the future: The production of esters of higher fatty acids from plant materials is of great interest for the manufacture of biodiesel. Heterogeneous catalysts can provide new routes for the environmentally benign production of biodiesel. Particulate heterogeneous catalysts can be readily separated from products following reaction allowing the catalyst to be reused, generating less waste, and consuming less energy.magnified imageDiesel engines are simple and powerful, and exhibit many advantages in energy efficiency and cost. Therefore, the production of higher fatty acid esters from plant materials has become of interest in recent years for the manufacture of biodiesel, a clean‐burning alternative fuel. The industrial production of biodiesel mostly proceeds in the presence of “soluble” catalysts such as alkali hydroxides and liquid acids. A considerable amount of energy is required for the purification of products and catalyst separation, and furthermore these catalysts are not reusable. This process results in substantial energy wastage and the production of large amounts of chemical waste. Particulate heterogeneous catalysts can be readily separated from products following reaction, allowing the catalyst to be reused and consuming less energy. This Minireview describes the environmentally benign production of biodiesel using heterogeneous catalysts such as solid bases, acid catalysts, and immobilized enzymes.
Epithelial expression of human papillomavirus type 16 E7 protein results in peripheral CD8 T‐cell suppression mediated by CD4+CD25+ T cells
Authors: Narayan Sharmal , Choyce Allison , Linedale Richard , Saunders Nicholas A. , Dahler Alison , Chan Emily , Fernando Germain J. , Frazer Ian H. , Leggatt Graham R. 
Published: January 2009

AbstractThe role of thymic versus peripheral epithelium in the regulation of the antigen‐specific CD8 T‐cell repertoire is still largely unresolved. We generated TCR‐β chain transgenic mice in which an increased frequency of peripheral CD8 T cells recognizes an epitope from a viral oncoprotein (HPV16E7) in the context of H‐2Db MHC class I. When T cells from these mice developed through the thymus of mice expressing functional E7 protein from a keratin 14 promoter, no major perturbation to transgenic T‐cell development in the thymus was observed in these double‐transgenic mice. In contrast, peripheral CD8 T‐cell responses in the single‐transgenic, K14E7 mice, including those unrelated to E7 antigen, are reduced whereas CD4 T‐cell responses and antibody production are unchanged in these mice. Peripheral non‐responsiveness among CD8 T cells was mediated largely by CD4+CD25+ T cells. This suggested that epithelium expressing HPV16E7 protein induces Treg that specifically down‐regulate CD8 T‐cell responses in the periphery. This may have important consequences for the treatment of cervical pre‐cancers and provides a model for understanding differential suppression of T and B lymphocyte subsets by Treg.
Expression of IL‐15RA or an IL‐15/IL‐15RA fusion on CD8+ T cells modifies adoptively transferred T‐cell function in cis
Authors: Rowley Jesse , Monie Archana , Hung Chien‐Fu , Wu T.‐C. 
Published: January 2009

AbstractIL‐15 and IL‐15 receptor alpha (IL‐15RA) play a significant role in multiple aspects of T‐cell biology. However, given the evidence that IL‐15RA can present IL‐15 in trans, the functional capacity of IL‐15RA expressed on CD8+ T cells to modify IL‐15 functions in cis is currently unclear. In the current study, we explore the functional consequences of IL‐15RA, expression on T cells using a novel method to transfect naive CD8+ T cells. We observed that RNA nucleofection led to highly efficient, non‐toxic, and rapid manipulation of protein expression levels in unstimulated CD8+ T cells. We found that transfection of unstimulated CD8+ T cells with IL‐15RA RNA led to enhanced viability of CD8+ T cells in response to IL‐15. Transfection with IL‐15RA enhanced IL‐15‐mediated phosphorylation of STAT5 and also promoted IL‐15‐mediated proliferation in vivo of adoptively transferred naïve CD8+ T cells. We demonstrated that IL‐15RA can present IL‐15 via cis‐presentation on CD8+ T cells. Finally, we showed that transfection with a chimeric construct linking IL‐15 to IL‐15RA cell autonomously enhances the viability and proliferation of primary CD8+ T cells and cytotoxic potential of antigen‐specific CD8+ T cells. The clinical implications of the current study are discussed.
Functional islet‐specific Treg can be generated from CD4+CD25− T cells of healthy and type 1 diabetic subjects
Authors: Long S. Alice , Walker Mindi R. , Rieck Mary , James Eddie , Kwok William W. , Sanda Srinath , Pihoker Catherine , Greenbaum Carla , Nepom Gerald T. , Buckner Jane H. 
Published: January 2009

AbstractCD4+CD25+FOXP3+ Treg cells require TCR engagement for suppressive function, thus ensuring that suppression occurs only in the presence of specific antigens; however, to date no studies have addressed the function of self‐antigen‐specific Treg in humans. These studies were designed to determine whether peripheral generation and function of islet antigen‐specific adaptive Treg are defective in human subjects with type 1 diabetes (T1D). Islet antigen‐specific adaptive Treg were induced in vitro by activation of CD4+FOXP3− T cells with glutamic acid decarboxylase and islet‐specific glucose‐6‐phosphate catalytic subunit‐related protein peptides in the context of T1D‐associated HLA‐DRβ alleles. Antigen‐specific Treg were characterized using flow cytometry for FOXP3 and class II tetramer and assessed for the ability to inhibit proliferation. These adaptive Treg were then compared with influenza‐specific Treg from the same study population. The function of tetramer+ cells that expressed FOXP3 was similar for both influenza and islet antigens generated from control and T1D subjects. In fact, the potency of suppression correlated with FOXP3 expression, not antigen specificity. Thus, these data suggest that development of functional adaptive Treg can occur in response to islet antigens and activation of islet‐specific Treg may potentially be used as a targeted immunotherapy in T1D.
Cover Picture: Eur. J. Immunol. 2/09
Authors: Aoshi Taiki , Carrero Javier A. , Konjufca Vjollca , Koide Yukio , Unanue Emil R. , Miller Mark J. 
Published: January 2009

AbstractThe cover image shows immunohistological staining of the white pulp (WP) and a bridging channel (BC) in the spleen of a BALB/c mouse and is taken from Aoshi et al. (pp. 417–425); CD11b staining is shown in blue, F4/80 in green and CD11c in red. In contrast to other reports, Aoshi et al. identified, by antibody staining, cell location and morphology, five different phagocytic populations (F4/801 macrophages, MARCO1 macrophages, MOMA‐11 macrophages, CD11b1 neutrophils and CD11c1 DC) involved in the splenic uptake of Listeria monocytogenes. In addition, MARCO1 macrophages are shown to be involved only in the very early stages of infection.
Synthesis, Characterization and OFET Properties of Amphiphilic Mixed (Phthalocyaninato)(porphyrinato)europium(III) Complexes
Authors: Ma Pan , Chen Yanli , Sheng Ning , Bian Yongzhong , Jiang Jianzhuang 
Published: January 2009

AbstractAmphiphilic mixed (phthalocyaninato)(porphyrinato)europium(III) triple‐decker complexes Eu2[Pc(15C5)4]2[T(C10H21)4P] (1) and Eu2[Pc(15C5)4]2[TPOPP] (2) [H2Pc(15C5)4 = 2,3,9,10,16,17,23,24‐tetrakis(15‐crown‐5)phthalocyanine; H2T(C10H21)4P = meso‐5,10,15,20‐tetra‐n‐decylporphyrin, H2TPOPP = meso‐5,10,15,20‐tetrakis(4‐pentyloxyphenyl)porphyrin] were designed and synthesized by the raise‐by‐one‐story method. These novel sandwich triple‐decker complexes were characterized by a wide range of spectroscopic methods, and they were also electrochemically studied. Highly ordered films were fabricated by the Langmuir–Blodgett (LB) technique into organic field‐effect transistors (OFETs). The devices display good OFET performance with a carrier mobility in the range 0.03–0.78 cm2 V–1 s–1. As expected, the devices show a low threshold voltage range from –1.19 to –4.34 V. The mobility of compound 1 reaches 0.78 cm2 V–1 s–1, which is the highest value so far achieved for LB film‐based OFETs, as a result of the narrow energy gap (1.04 eV) of this compound.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Preparation of Triaryl‐ and Triheteroarylmethanes under Ytterbium Triflate Catalysis and Solvent‐Free Conditions
Authors: Genovese Salvatore , Epifano Francesco , Pelucchini Caroline , Curini Massimo 
Published: January 2009

AbstractTriaryl‐ and triheteroarylmethanes have been synthesized in very good yield under solvent‐free conditions from differently substituted aldehydes and 2‐methylfuran or methoxybenzene in the presence of Yb(OTf)3 as catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Carbohydrate‐Based Pyridine‐2‐carboxamides for Mo‐Catalyzed Asymmetric Allylic Alkylations
Authors: Del Litto Raffaella , Benessere Vincenzo , Ruffo Francesco , Moberg Christina 
Published: January 2009

AbstractBis(pyridine‐2‐carboxamides) were prepared from 1,2‐diamines obtained from α‐D‐glucose and α‐D‐mannose. The ligands were assessed in molybdenum‐catalyzed asymmetric allylic alkylations (AAA) by using both methyl (E)‐3‐phenyl‐2‐propenyl and methyl rac‐1‐phenyl‐2‐propenyl carbonates and dimethyl malonate as nucleophile under microwave irradiation. High enantioselectivity (99 % ee) and high regioselectivity (49:1 in favour of the branched isomer) were observed in reactions of the linear achiral substrate in the presence of 10 mol‐% of a catalyst prepared from a ligand derived from glucose. Somewhat lower enantioselectivity (up to 96 % ee) was observed in reactions with the branched racemic carbonate by using the same ligand.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Comparison of aromatic and alkyl micelles for the electrokinetic determination of phthalates in virgin olive oil
Authors: Morales‐Cid Gabriel , Cárdenas Soledad , Simonet Bartolomé M. , Valcárcel Miguel 
Published: January 2009

AbstractTwo electrokinetic methods for the separation of phthalates are proposed. One uses 25 mM sodium borate and 50 mM sodium taurodeoxycholate adjusted to pH 2.8, and the other uses 15 mM ammonium tetraborate, 100 mM SDS, 0.25% w:v hydroxypropylmethyl cellulose (HPMC) and 5% v:v methanol (MeoH) adjusted to pH 9. The BGE containing SDS micelles as the pseudo‐stationary phase provided better analytical figures of merit, particularly as regards LOD (0.4–1.4 mg/L) and precision (1.1–6.5%). Adding MeoH and HPMC to the BGE proved essential in order to obtain narrow and symmetric peaks. The proposed method was successfully used to determine phthalates in virgin olive oil. Recoveries from spiked samples ranged from 96 to 106%. The precision obtained in the analysis of real samples, as RSD, was better than 6.8%.