bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of the growth for the microalga Chlorella vulgaris by photo‐bio‐calorimetry and other on‐line and off‐line techniques
Authors: Patiño Rodrigo , Janssen Marcel , von Stockar Urs 
Published: September 2006

AbstractCalorimetry and other on‐line techniques are used for the first time as complement to the traditional off‐line methods in order to follow the growth of the green Chlorella vulgaris microalgae. A 2‐L photo‐bio‐reactor was adapted from a commercial calorimeter used previously to study heterotrophic microbial growth. An external source of light was added to favor the photosynthesis of the autotrophic cells. Heterotrophic growth was also tested with external glucose in the broth. A third mode, mixotrophic, allowed faster autotrophic plus heterotrophic growth. Calorimetric measurements were performed considering the corresponding calibrations in order to consider only the energy involved during the microalgal growth. The three different modes of Chlorella cultures were energetically characterized. Besides calorimetry, the weight of diluted nitric acid added to maintain the pH of the culture was correlated with the cellular growth and the nitrogen composition of the algae. Additionally, the on‐line infrared spectroscopy proved to be an efficient technique to follow the composition of the broth in glucose, nitrates, and phosphates. These results were compared and complemented with some classic off‐line techniques used to track this kind of cultures. Biotechnol. Bioeng. 2007;96:757–767. © 2006 Wiley Periodicals, Inc.
Protein instability during HIC: Hydrogen exchange labeling analysis and a framework for describing mobile and stationary phase effects
Authors: Xiao Yunzhi , Jones Tara T. , Laurent Abigail H. , O'Connell John P. , Przybycien Todd M. , Fernandez Erik J. 
Published: September 2006

AbstractUnfolding of marginally stable proteins is a significant factor in commercial application of hydrophobic interaction chromatography (HIC). In this work, hydrogen‐deuterium isotope exchange labeling has been used to monitor protein unfolding on HIC media for different stationary phase hydrophobicities and as a function of ammonium sulfate concentration. Circular dichroism and Raman spectroscopy were also used to characterize the structural perturbations experienced by solution phase protein that had been exposed to media and by protein adsorbed on media. As expected, greater instability is seen on chromatographic media with greater apparent hydrophobicity. However, increased salt concentrations also led to more unfolding, despite the well‐known stabilizing effect of ammonium sulfate in solution. A thermodynamic framework is proposed to account for the effects of salt on both adsorption and stability during hydrophobic chromatography. Using appropriate estimates of input quantities, analysis with the framework can explain how salt effects on stability in chromatographic systems may contrast with solution stability. Biotechnol. Bioeng. 2007;96: 80–93. © 2006 Wiley Periodicals, Inc.
Continuous Symmetry Analysis of NMR Chemical Shielding Anisotropy
Authors: Steinberg Avital , Karni Miriam , Avnir David 
Published: September 2006

AbstractMolecular symmetry is a key parameter which dictates the NMR chemical shielding anisotropy (CSA). Whereas correlations between specific geometrical features of molecules and the CSA are known, the quantitative correlation with symmetry—a global structural feature—has been unknown. Here we demonstrate a CSA/symmetry quantitative relation for the first time: We study how continuous deviation from exact symmetry around a nucleus affects its shielding. To achieve this we employed the continuous symmetry measures methodology, which allows one to quantify the degree of content of a given symmetry. The model case we use for this purpose is a population of distorted SiH4 structures, for which we follow the 29Si CSA as a function of the degree of tetrahedral symmetry and of square‐planar symmetry. Quantitative correlations between the degree of these symmetries and the NMR shielding parameters emerge.
On the Mechanism of the Ascorbic Acid‐Induced Release of Nitric Oxide from N‐Nitrosated Tryptophan Derivatives: Scavenging of NO by Ascorbyl Radicals
Authors: Kytzia Anna , Korth Hans‐Gert , Sustmann Reiner , de Groot Herbert , Kirsch Michael 
Published: September 2006

AbstractDuring the past years, there has been increasing interest in endogenous nitric oxide storage compounds. Recently, we briefly reported on the ascorbate‐dependent release of nitric oxide (.NO) from N‐nitrosotryptophan derivatives. In the present study, the underlying mechanism of .NO release is studied in more detail, primarily utilizing N‐acetyl‐N‐nitrosotryptophan (NANT) as a model compound. The initial rate of the ascorbate‐induced release of nitric oxide has been found to correspond to the rate of NANT decay. In this process, N‐acetyltryptophan (NAT) is produced almost quantitatively. The final yield of nitrite amounted to around 90 % with respect to the applied amount of NANT. However, the total release of nitric oxide was only 60 %, as determined by using an FNOCT‐4(fluorescent nitric oxide cheletropic trap number 4) assay. Besides nitric oxide, a second volatile product, dinitrogen oxide (N2O), has been identified by using 15N NMR spectrometry, strongly indicating the intermediacy of nitroxyl (HNO). The formation of intermediate ascorbyl radical anions during the NANT–ascorbate reaction has been monitored by using ESR spectrometry. Unexpectedly, it was found that the primary oxidized product of vitamin C, dehydroascorbic acid (DHA), efficiently consumes nitric oxide. Since ESR spectrometry further revealed that ascorbyl radical anions are also generated during the spontaneous decay of DHA, the DHA–nitric oxide reaction is related to recombination of .NO with the thus formed ascorbyl radical anions. A conclusively established mechanism of the NANT–ascorbate reaction is presented, with O‐nitrosoascorbate as a key intermediate, as additionally supported by CBS‐QB3 calculations. The present study suggests that vitamin C and its oxidation products can chemically counterbalance endogenous nitric oxide levels.
Catalytic PH Activation by Ti and Zr Catalysts
Authors: Masuda Jason D. , Hoskin Aaron J. , Graham Todd W. , Beddie Chad , Fermin Maria C. , Etkin Nola , Stephan Douglas W. 
Published: September 2006

AbstractCatalytic dehydrocoupling of phosphines was investigated using the anionic zirconocene trihydride salts [Cp*2Zr(μ‐H)3Li]3 (1 a) or [Cp*2Zr(μ‐H)3K(thf)4] (1 b), and the metallocycles [CpTi(NPtBu3)(CH2)4] (6) and [Cp*M(NPtBu3)(CH2)4] (M=Ti 20, Zr 21) as catalyst precursors. Dehydrocoupling of primary phosphines RPH2 (R=Ph, C6H2Me3, Cy, C10H7) gave both dehydrocoupled dimers RP(H)P(H)R or cyclic oligophosphines (RP)n (n=4, 5) while reaction of tBu3C6H2PH2 gave the phosphaindoline tBu2(Me2CCH2)C6H2PH (9). Stoichiometric reactions of these catalyst precursors with primary phosphines afforded [Cp*2Zr((PR)2)H][K(thf)4] (R=Ph 2, Cy 3, C6H2Me3 4), [Cp*2Zr((PPh)3)H][K(thf)4] (5), [CpTi(NPtBu3)(PPh)3] (7) and [CpTi(NPtBu3)(μ‐PHPh)]2 (8), while reaction of 6 with (C6H2tBu3)PH2 in the presence of PMe3 afforded [CpTi(NPtBu3)(PMe3)(P(C6H2tBu3)] (10). The secondary phosphines Ph2PH and (PhHPCH2)2CH2 also undergo dehydrocoupling affording (Ph2P)2 and (PhPCH2)2CH2. The bisphosphines (CH2PH2)2 and C6H4(PH2)2 are dehydrocoupled to give (PCH2CH2PH)2 (12) and (C6H4P(PH))2 (13) while prolonged reaction of 13 gave (C6H4P2)8 (14). The analogous bisphosphine Me2C6H4(PH)2 (17) was prepared and dehydrocoupling catalysis afforded (Me2C6H2P(PH))2 (18) and subsequently [(Me2C6H2P2)2(μ‐Me2C6H2P2)]2 (19). Stoichiometric reactions with these bisphosphines gave [Cp*2Zr(H)(PH)2C6H4][Li(thf)4] (22), [CpTi(NPtBu3)(PH)2C6H4]2 (23) and [Cp*Ti(NPtBu3)(PH)2C6H4] (24). Mechanistic implications are discussed.
Probing Structural Effects on Replication Efficiency through Comparative Analyses of Families of Potential Self‐Replicators
Authors: Kassianidis Eleftherios , Pearson Russell J. , Philp Douglas 
Published: September 2006

AbstractA formidable synthetic apparatus for the creation of nanoscale molecular structures and supramolecular assemblies through molecular structures can potentially be created from systems that are capable of parallel automultiplication (self‐replication). In order to achieve this goal, a detailed understanding of the relationship between molecular structure and replication efficiency is necessary. Diastereoisomeric templates that are capable of specific and simultaneous autocatalysis have been synthesised. A systematic experimental and theoretical evaluation of their behaviour and that of structurally‐related systems reveals the key determinants that dictate the emergence of self‐replicative function and defines the structural space within which this behaviour is observed.
Local Aromaticity in Polycyclic Aromatic Hydrocarbons: Electron Delocalization versus Magnetic Indices
Authors: Bultinck Patrick , Fias Stijn , Ponec Robert 
Published: September 2006

AbstractThe local aromaticity of benzenoid rings is examined by means of the Polansky index (P) and generalized population analysis (GPA). The results are found to agree very well with recently published circuit‐condensed ring currents and magnetic‐energetic aromaticity indices, but no correlation is found with nucleus independent chemical shifts (NICS). This is usually seen as a manifestation of the more general multidimensional nature of aromaticity. This paper examines the sources for the observed correlations, showing that some indices give conflicting results because they inherently reflect different phenomena.
Mechanism of the Condensation of Homocysteine Thiolactone with Aldehydes
Authors: Jakubowski Hieronim 
Published: September 2006

AbstractChemical reactivity of homocysteine thiolactone (HTL) has been implicated in cardiovascular disease. Owing to its aminoacyl‐thioester character, HTL undergoes facile electrophilic and nucleophilic reactions at its amino and activated‐carboxyl group, respectively. To gain insight into the mechanism of the reactions involving its amino group, the kinetics of the condensation of homocysteine thiolactone with formaldehyde, acetaldehyde, and pyridoxal phosphate, were analyzed in the pH range from 5 to 10. The reactions were first order with respect to HTL, aldehyde, and hydroxide ion concentrations. Of the two ionic species of HTL (pKa=6.67±0.05), the acid form HTL+ was ∼100‐fold more reactive than the base form HTL0. The reactions of HTL with aldehydes involve intermediate adducts. The conversion of the intermediate carbinolamine to a product, 1,3‐tetrahydrothiazine‐4‐carboxylic acid or its 2‐substituted analogue, occurs in a two‐step reaction. The first step involves hydrolysis of the thioester bond in the intermediate, facilitated by anchimeric assistance by the oxygen of the carbinolamine group of the intermediate. The second step involves an attack of the liberated thiolate on the aldehyde‐derived carbon of the intermediate, affording 1,3‐tetrahydrothiazine‐4‐carboxylic acid or its 2‐substituted analogue. An unusual feature of these reactions is that the formation of the carbinolamine group increases the reactivity of the thioester bond of HTL ∼104‐fold. The facile formation of tetrahydrothiazines may contribute to HTL elimination from the human body.
Structure–Activity Relationship Studies of 3‐Aroylindoles as Potent Antimitotic Agents
Authors: Liou Jing‐Ping , Mahindroo Neeraj , Chang Chun‐Wei , Guo Fu‐Ming , Lee Sandy Wen‐Hsing , Tan Uan‐Kang , Yeh Teng‐Kuang , Kuo Ching‐Chuan , Chang Yi‐Wei , Lu Ping‐Hsun , Tung Yen‐Shih , Lin Ke‐Ta , Chang Jang‐Yang , Hsieh Hsing‐Pang 
Published: September 2006

AbstractThe concise synthesis and structure–activity relationship (SAR) studies of 3‐aroylindoles were carried out in an effort to improve the potency and solubility of anticancer drug candidate BPR0L075 (8) by exploring structure modifications through three regimens: substitution of the B ring, at the N1 position, and of the 3‐carbonyl linker. The SAR information revealed that the methoxy group of the B ring could be replaced with an electron‐donating group such as methyl (in compound 9) or N,N‐dimethylamino (in compound 13) while retaining both strong cytotoxic and antitubulin activities. The introduction of amide (compounds 30–33) and carbamate (compounds 34–37) functionalities at the N1 position of 8 gave analogues with potent antiproliferative activities. The cytotoxic potency of 8 was improved by replacing the carbonyl group with sulfide (compound 41) or oxygen (compound 43), indicating that the carbonyl moiety is important but not essential. The N,N‐dimethylamino derivative 13 not only displayed potent cytotoxicity and antitubulin activity, but also showed a markedly improved physicochemical profile relative to the parent compound.
Prediction of ADMET Properties
Authors: Norinder Ulf , Bergström Christel A. S. 
Published: September 2006

AbstractThis Review describes some of the approaches and techniques used today to derive in silico models for the prediction of ADMET properties. The article also discusses some of the fundamental requirements for deriving statistically sound and predictive ADMET relationships as well as some of the pitfalls and problems encountered during these investigations. It is the intension of the authors to make the reader aware of some of the challenges involved in deriving useful in silico ADMET models for drug development.
Effect of Architecture on the Tensile Properties of Triblock Copolymers in a Lamellar Phase
Authors: Huang Rui , Jiang Ying , Liang Haojun 
Published: September 2006

AbstractWe have used self‐consistent field theory to calculate the tensile moduli of triblock copolymers in lamellar microstructures prepared from linear and star architectures. The extensional moduli K33 are the main contributors to the tensile moduli, and the contribution of ${{\rm{K}}{}_{33}^{{\rm{U}}\,} }$ (the internal energy contribution to K33) is the main component of the value of K33. We find that the tensile moduli of ABC three‐miktoarm star terpolymers are smaller than those of ABC linear triblock copolymers having identical components, presumably for two main reasons. First, for the ABC three‐miktoarm star terpolymers, the contributions of ${{\rm{K}}{}_{33}^{{\rm{U}}\,} }$ are larger than those of the linear triblock copolymers; we attribute this phenomenon to the star terpolymers having smaller lamellar domain sizes at equilibrium relative to those of the linear triblock copolymers. Second, conformational entropies play an important role in affecting the tensile moduli, mainly because of the different degrees of freedom of the various chains. In contrast, the shear moduli contribute negligibly to the tensile moduli.
Toward the Rational Design of Functionalized Pentacenes: Reduction of the Impact of Functionalization on the Reorganization Energy
Authors: Chen Hsing‐Yin , Chao Ito 
Published: September 2006

AbstractFor the widely studied high‐carrier‐mobility species, pentacene, it is found that perfluorination turned it into an n‐type organic field‐effect transistor (OFET), but doubled the internal reorganization energy (λ) of the electron/hole hopping. Here, Cl‐ and N‐functionalized pentacenes are designed to test two strategies that may reduce the impact of functionalization on λ. Calculation results show that the strategies are feasible. Moreover, combined with crystal‐structure data of Cl‐ and N‐functionalized aromatic compounds, it is concluded that compared to fluorination, the presence of Cl and N atoms in pentacene not only reduces the influence of functionalization on λ and affords a larger window for tuning HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies, but also provides the opportunity to promote π‐stacked structures through Cl⋅⋅⋅Cl and CH⋅⋅⋅N interactions.
Control of graft‐versus‐host disease by regulatory T cells: Which level of antigen specificity?
Authors: Martinic Marianne M. , von Herrath Matthias G. 
Published: September 2006

AbstractRegulatory T cells (Tregs) are essential to suppress harmful self‐reactive T cell responses. A paper in this issue of the European Journal of Immunology analyzes the role of Tregs in preventing syngeneic graft‐versus‐host disease (sGVHD). In this Commentary, we address the role of antigen specificity of Tregs in this context as well as future protocols for successful allogeneic grafts transplantation. Such ideal interventions will hopefully retain a diverse repertoire of pathogen‐specific T cells, while maintenance of self‐, foreign‐ and alloantigen‐specific Tregs ensures life‐long graft tolerance.See accompanying article http://www.dx.doi.org/10.1002/eji.200636434
Protection from autoimmunity: Immunological indifference versus T‐cell mediated suppression?
Authors: Chatenoud Lucienne 
Published: September 2006

AbstractA long‐held dogma was that immune tolerance could only be achieved through central deletion of potentially reactive cells at their site of origin, a concept supported by the direct demonstration of natural negative selection in bone marrow and thymus; however, it is now extensively documented that although deletion mechanisms ensure the elimination of most autoreactive cells, this purging is far from complete.There are major immune mechanisms that ensure tolerance in the periphery which are clearly non‐deletional. A paper in this issue of the European Journal of Immunology demonstrates that T cell‐mediated immunoregulation involving in particular the CTLA‐4 signaling pathway plays a key role in controlling the pathogenic potential of fully differentiated autoreactive T cells.See accompanying article http//dx.doi.org/10.1002/eji.200636432
Synthesis, Structure, and Polymerization Activity of a Titanium Complex with a Chelating [(Hydroxy‐κO)amino‐κN]phenolato(2−)‐κO Ligand
Authors: Kraft Bradley M. , Huang Kuo‐Wei , Cole Adam P. , Waymouth Robert M. 
Published: August 2006

AbstractA novel titanium complex with a chelating nitroxide ligand, dichloro‐2‐{[(hydroxy‐κO)phenylamino‐κN)phenylmethyl}phenolato(2−)‐2κO}(tetrahydrofuran)titanium (1), was synthesized and characterized by NMR spectroscopy, elemental analysis, and single‐crystal X‐ray crystallography. In the presence of methylaluminoxane (MAO), 1 displayed moderate activity for the polymerization of propylene.
Effect of Structure of Functionalizing Molecules on the Inter‐Macromolecular Reactions and Blending of Poly(ethylene‐co‐propylene) (EPM) with Poly(6‐aminohexanoic Acid) (PA6)
Authors: Passaglia Elisa , Coltelli Maria‐Beatrice , Ciardelli Francesco 
Published: August 2006

AbstractTwo different functionalizing systems, i.e., monohexadecyl maleate (= hexadecyl hydrogen (2Z)‐but‐2‐enedioate) in the presence of dicumyl peroxide (= bis(1‐methyl‐1‐phenylethyl) peroxide) or 4‐carboxybenzenesulfonazide (= 4‐(azidosulfonyl)benzoic acid), were used in distinct experiments to perform in a one‐step procedure the formation of a EPM–PA6 graft copolymer, necessary to obtain a compatibilized blend, from a molten mixture of ethylene–propylene copolymer (EPM) and polyamide 6 (PA6). The characterization of the graft polymer by selective solvent extraction of the blends and the subsequent IR and NMR analysis of the various fractions established the occurrence of functionalization reactions preferentially onto the polyolefin with both reagents. Also the formation in good yield of graft copolymers at the phases interface was observed. Moreover, the morphology and thermal characterizations of the blends by means of SEM and DSC analyses were used to evaluate the compatibilization extent in comparison with blends obtained by the conventional two‐step procedure or by the one‐step procedure with commercial maleic acid derivatives.
Expanding the Scope of Atropisomeric Monodentate P‐Donor Ligands in Asymmetric Catalysis: Hydrogen‐Transfer Reduction of α,β‐Unsaturated Acid Derivatives by Rhodium/Ph‐binepine Catalysts
Authors: Alberico Elisabetta , Nieddu Ilenia , Taras Rossana , Gladiali Serafino 
Published: August 2006

AbstractA range of α,β‐unsaturated acids and esters have been selectively reduced to the corresponding saturated acid derivatives by hydrogen transfer. As the reducing agent, formic acid was used in the presence of RhI complexes formed with the powerful chiral ligand Ph‐binepine (1), an axially chiral binaphthalene‐type monodentate P‐donor ligand. Very high stereoselectivities (up to 97% ee) were obtained in the case of itaconic acid (2a).
Bronchiolitis obliterans with organizing pneumonia after rituximab therapy for non‐Hodgkin's lymphoma
Authors: Biehn Suzanne E. , Kirk David , Rivera M. Patricia , Martinez Antonio E. , Khandani Amir H. , Orlowski Robert Z. 
Published: September 2006

AbstractRituximab is a chimeric, anti‐CD20 monoclonal antibody initially approved for relapsed, refractory indolent B‐cell non‐Hodgkin's lymphoma (NHL), and is being applied in an increasing variety of clinical scenarios. Most adverse events are due to an infusion‐related symptom complex, and severe pulmonary complications are rare. We describe a case of an NHL patient who received rituximab and developed symptomatic, biopsy‐proven multinodular bronchiolitis obliterans with organizing pneumonia (BOOP). This is the first reported case of BOOP associated with single‐agent rituximab, and along with two other patients we describe, as well as two prior reports of BOOP in NHL patients receiving rituximab‐based combinations, strengthens the possibility of a causal relationship. Moreover, these findings suggest that the incidence of BOOP following rituximab therapy may be higher than has been previously appreciated. Physicians utilizing rituximab should be aware of this association given the difficulty of differentiating between presentations of BOOP and neoplastic pulmonary processes. Copyright © 2006 John Wiley & Sons, Ltd.
Presence of a thermoregulatory hot spot in the prothorax of the large carpenter bee and the bumble bee
Authors: Volynchik Stanislav , Plotkin Marian , Ermakov Natalya Y. , Bergman David J. , Ishay Jacob S. 
Published: September 2006

AbstractIn both the large carpenter bee (Xylocopa pubescens) and the bumblebee (Bombus terrestris), a hot spot was detected in the center of the prothorax on its dorsal‐external aspect. In both cases, the temperature in this hot spot was found to be greater than the ambient temperature and that at the tip of the gaster. In B. terrestris, it was higher by 9–10°C from that at the gaster tip and by 15–16°C from the ambient temperature, while in X. pubescens the corresponding differences were 11–20°C and 18–19°C, respectively. The recorded thermal differences were not fixed but were rather variable, temporally as well as individually, but invariably all individuals measured showed these temperature differences. Furthermore, in none of the studied specimens was a hot spot detected in any part of the body other than the prothorax. From this hot spot in the prothorax, there is a cascade of temperatures in both directions, that is, anteriorly towards the head and posteriorly towards the gaster, with a graded drop in temperature in either direction. This article discusses possible reasons for the existence of such a hot spot in this particular location (the prothorax), its role or function, and its mode of operation. The authors speculate that it is a thermoregulatory center (for heating or cooling) that might be present in possibly all Hymenoptera that spend a considerable part of their life flying, regardless of whether they are social, parasocial, or solitary. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.