bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD8+ NK cells are predominant in chimpanzees, characterized by high NCR expression and cytokine production, and preserved in chronic HIV‐1 infection
Authors: Rutjens Erik , Mazza Stefania , Biassoni Roberto , Koopman Gerrit , Ugolotti Elisabetta , Fogli Manuela , Dubbes Rob , Costa Paola , Mingari Maria C. , Greenwood Edward J. D. , Moretta Lorenzo , DeMaria Andrea , Heeney Jonathan L. 
Published: March 2010

AbstractHIV‐1 infection in humans results in an early and progressive NK cell dysfunction and an accumulation of an “anergic” CD56− CD16+ NK subset, which is characterised by low natural cytotoxicity receptor expression and low cytokine producing capacity. In contrast to humans, chimpanzee NK cells do not display a distinguishable CD56bright and CD56dim subset but, as shown here, could be subdivided into functionally different CD8+ and CD8− subsets. The CD8+ NK cells expressed significantly higher levels of triggering receptors including NKp46 and, upon in vitro activation, produced more IFN‐γ, TNF‐α and CD107 than their CD8− counterparts. In addition, chimpanzee CD8− NK cells had relatively high levels of HLA‐DR expression, suggestive of an activated state. Killing inhibitory receptors were expressed only at low levels; however, upon in vitro stimulation, they were up‐regulated in CD8+ but not in CD8− NK cells and were functionally capable of inhibiting NKp30‐triggered killing. In contrast to HIV‐1‐infected humans, infected chimpanzees maintained their dominant CD8+ NK cell population, with high expression of natural cytotoxicity receptors.
Surfactantless Synthesis and the Surface‐Enhanced Raman Spectra and Catalytic Activity of Differently Shaped Silver Nanomaterials
Authors: Li Xuanhua , Wang Jin , Zhang Yongxing , Li Mingqiang , Liu Jinhuai 
Published: March 2010

AbstractThis paper reports the transition of shape‐selective silver nanostructures from nanoplates to nanodendrites and to nanospheres made up of primary nanoparticles that can be readily controlled by changing the molar ratio of vitamin C to AgNO3. In addition, the formation of Ag nanostructures with multiple shapes can be readily controlled depending on the efficient density‐assisted self‐assembly synthesis. The surface‐enhanced effects and catalytic activity of the formed Ag nanomaterials are strongly dependent on the surface morphologies of Ag nanomaterials, and compared with the other Ag nanomaterials presented here, the nanospheres made up of primary nanoparticles showed excellent surface‐enhanced effects and catalytic activity.
A Facile Approach to Fabrication of Hexagonal‐Phase NaYF4:Yb3+, Er3+ Hollow Nanospheres: Formation Mechanism and Upconversion Luminescence
Authors: Zhao Junwei , Liu Xiaomin , Cui Di , Sun Yajuan , Yu Yi , Yang Yifei , Du Chuang , Wang Yu , Song Kai , Liu Kai , Lu Shaozhe , Kong Xianggui , Zhang Hong 
Published: March 2010

AbstractThe hexagonal‐phase NaYF4:Yb3+, Er3+ hollow nanospheres (HNS) have been successfully prepared for the first time by means of a hydrothermal route with the aid of polyethylenimine (PEI) as a surfactant. The nitrogen adsorption/desorption isotherms demonstrated the porous nature of the NaYF4 HNS. The formation mechanism was explored based on the effects of the reaction parameters. The NaYF4 solid spheres underwent a dissolution‐recrystallisation transformation and a hollowing process when the hydrothermal reaction time was prolonged. The localised Ostwald ripening mechanism was proposed to account for the formation of NaYF4 HNS, in which loose aggregations were found to be crucial. The upconversion luminescence of NaYF4:Yb3+, Er3+ HNS was also investigated. It is expected that these NaYF4 HNS might have potential in applications as building blocks for biolabels and drug‐delivery.
Thermal Decomposition Reactions as a Tool for the Synthesis of New Thermodynamic Metastable Modifications: Synthesis, Structures, and Properties of (Formato)nickel(II) Coordination Polymers Based on 4,4′‐Bipyridine
Authors: Boeckmann Jan , Wriedt Mario , Näther Christian 
Published: March 2010

AbstractThe reaction of nickel formate with 4,4′‐bipyridine (bipy) in aqueous solution at room temperature leads to the formation of the hydrated compound [Ni(HCO2)2(H2O)(bipy)·4H2O]n (1) reported recently. On heating, compound 1 decomposes into the new anhydrous compound of composition [Ni(HCO2)2(bipy)]n (2II), which decomposes on further heating. Interestingly, if the anhydrous compound is prepared from solution, a new modification 2I is obtained. Investigations on the stability of both forms show that modification 2I presents the thermodynamically most stable form between room and decomposition temperature, whereas modification 2II, which can only be prepared by thermal decomposition, is metastable. In the crystal structure of 2I, the Ni2+ cations are coordinated by four μ2‐anti,anti bridging formato anions and two bridging μ2‐bipy ligands in a slightly distorted octahedralgeometry. The formato anions bridge the metal cations in zigzag chains, which are further connected by μ2‐anti,anti formato anions and bipy ligands to give a three‐dimensional coordination network. IR spectroscopic investigations on the metastable form 2II also indicate that all formato anions act as bridging ligands. Magnetic measurements of the hydrated and anhydrous compounds reveal different behavior with a ferromagnetic ordering for compound 2I and an antiferromagnetic ordering for compound 1. For form 2II, only Curie–Weiss paramagnetism was found.
Synthesis, Structure, and Magnetic Properties of Amine‐Templated Transition‐Metal Phosphites
Authors: Ramaswamy Padmini , Mandal Sukhendu , Hegde Nayana N , Prabhu Ramanath , Banerjee Debmalya , Bhat S. V. , Natarajan Srinivasan 
Published: March 2010

AbstractTransition‐metal phosphites of cobalt and vanadium, [C4N2H12][Co(HPO3)2] (I), [C4N2H14][Co(HPO3)2] (II), [Co(C10H8N2)(H2PO3)2] (III), [C4N2H14][VIIIF(HPO3)2]·H2O (IV), and [C3N2H5]2[V4III(H2O)3(HPO3)4(HPO4)3] (V), have been synthesized and characterized. Organophosphorus esters were employed to stabilize cobalt in tetrahedral coordination and also to prepare the low‐dimensional structures, which are otherwise difficult to synthesize. The structures have one‐ (I, II, IV), two‐ (III) and three‐dimensionally (V) extended networks built up by the linking of metal polyhedra and phosphite units. Another vanadyl phosphite, [C2N2H10][(VIVO)3(H2O)(HPO3)4]·H2O,15 was also prepared and investigated extensively by ESR, magnetic susceptibility, and other studies. All the compounds in the present study exhibit antiferromagnetic interactions. Well‐established magnetic models have been used to fit the experimental data. The compounds have also been characterized in detail by using UV/Vis spectroscopic studies.
[Bis(pyrazolyl)methane]palladium Complexes with a Carbosilane Dendritic Structure
Authors: Sánchez‐Méndez Alberto , de Jesús Ernesto , Flores Juan C. , Gómez‐Sal Pilar 
Published: March 2010

AbstractA series of carbosilane dendritic ligands of general formula Gn‐[CH(3,5‐Me2pz)2]m and their corresponding palladium(II) complexes Gn‐[CH(3,5‐Me2pz)2Pd(X)Cl]m (X = Cl or Me) containing four (m = 1) or eight (m = 2) terminal bis(pyrazolyl)methane moieties, along with their corresponding monometallic counterparts (m = 0), have been synthesized. An appropriate choice of poly(pyrazolyl)methane ligand has allowed us to overcome the steric and solubility issues that previously limited the synthesis of polymetallic dendrimers containing (scorpionato)palladium complexes. The evaluation of these complexes as catalyst precursors in the Heck reaction between p‐iodotoluene and methyl acrylate is also reported.
Synthesis, NMR, and Conformational Studies of Cyclic Oligo‐(1→6)‐β‐D‐Glucosamines
Authors: Gening Marina L. , Titov Denis V. , Grachev Alexey A. , Gerbst Alexey G. , Yudina Olga N. , Shashkov Alexander S. , Chizhov Alexander O. , Tsvetkov Yury E. , Nifantiev Nikolay E. 
Published: March 2010

AbstractThe first synthesis of a series of homologous cyclic oligo‐(1→6)‐β‐D‐glucosamines consisting of two to seven residues and representing a new type of functionalized cyclic oligosaccharides is reported. Remarkably high yields of the studied macrocyclization reaction irrespective of the length of the acyclic precursors were observed. In the case of compounds constituted of four to seven glucosamine units α‐stereoisomers formed as side products despite the presence of a strongly participating 2‐N‐phthaloyl group to control β‐glycosylation. Both phenomena may be accounted for by conformational features of the linear bifunctional precursors. According to computer modeling and NMR conformational studies, the described linear (1→6)‐β‐linked oligoglucosamines exist in a right‐handed helix‐like conformation, in which the glycosyl donor and acceptor moieties are prearranged in a way that facilitates intramolecular glycosylation from the α‐side. Prepared cyclo‐oligoglucosamines differ in their conformational flexibilities, as illustrated by their spectral characteristics and calculated asphericity distributions. Moreover, the obtained compounds do not possess a distinct hydrophobic cavity, which is in contrast to the well‐known cyclodextrins. All these characteristics provide an excellent basis for the use of these novel cyclic oligosaccharides as scaffolds for the construction of biomolecular conjugates.
Solid‐Phase Synthesis of Aza‐Kahalalide F Analogues: (2R,3R)‐2‐Amino‐3‐azidobutanoic Acid as Precursor of the Aza‐Threonine
Authors: Izzo Irene , Acosta Gerardo A. , Tulla‐Puche Judit , Cupido Tommaso , Martin‐Lopez Maria Jesus , Cuevas Carmen , Albericio Fernando 
Published: March 2010

AbstractThe solid‐phase synthesis of six novel analogues of Kahalalide F (KF), a natural product currently undergoing Phase II clinical trials, is reported. In all these compounds, amides were used as isosteres for the depsi bond. For two of these compounds, we performed an efficient synthesis of N‐Fmoc‐protected (2R,3R)‐2‐amino‐3‐azidobutanoic acid, precursor of the aza‐threonine. This is the first example of the solid‐phase reduction of an azide group in the preparation of aza‐Thr‐containing peptides in the solid phase.
Esterification of Maleamic Acids without Double Bond Isomerization
Authors: Sánchez Albert , Pedroso Enrique , Grandas Anna 
Published: March 2010

AbstractActivation of the carboxylic acid group of a maleamic acid by treatment with an arenesulfonyl chloride followed by addition of an alcohol affords a fumaramate or a maleamate, depending on the reaction conditions. The E isomer is obtained when the acid is treated with nearly equimolar amounts of 2,4,6‐triisopropylbenzenesulfonyl chloride and an alcohol in pyridine. Replacement of pyridine by 2‐picoline and use of a larger excess of activating agent (mesitylenesulfonyl chloride) and alcohol affords the Z isomer. In both cases, high diastereomeric excesses and yields are achieved.
Chiral and Achiral Charge‐Transfer Chromophores with a Dendralene‐Type Backbone by Electronically Controlled Cycloaddition/Cycloreversion Cascades
Authors: Frank Brian B. , Kivala Milan , Camafort Blanco Berta , Breiten Benjamin , Schweizer W. Bernd , Laporta Philip R. , Biaggio Ivan , Jahnke Eike , Tykwinski Rik R. , Boudon Corinne , Gisselbrecht Jean‐Paul , Diederich François 
Published: March 2010

AbstractChiral and achiral push‐pull chromophores have been prepared by cascades of sequential [2+2] cycloadditions of tetracyanoethene (TCNE) and tetrathiafulvalene (TTF) to different oligoynes. Thermal [2+2] cycloaddition of TCNE to donor‐substituted alkynes, followed by electrocyclic ring‐opening of the initially formed cyclobutenes, affords donor‐substituted 1,1,4,4‐tetracyanobuta‐1,3‐dienes (TCBDs). Similarly, TTF reacts with electron‐deficient C≡C bonds to give the corresponding buta‐1,3‐diene derivatives, 1,2‐bis(1,3‐dithiol‐2‐ylidene)ethanes. Thus, achiral [AB]‐type oligomers were synthesized from N,N‐dialkylanilino (DAA)‐substituted tetraynes and hexaynes and chiral [AB]‐type oligomers from alkyne‐substituted 1,1′‐binaphthalenes. The [AB]‐type oligomers exhibit complex conformational equilibria in solution, as revealed by 1H and 13C NMR spectroscopy. Therefore, the circular dichroism (CD) spectra of the chiral [AB]‐type oligomers were measured to investigate whether a preferred conformation of the dendralene‐type backbone is induced by the optically active 1,1′‐binaphthalene moiety. Electrochemical studies by cyclic voltammetry (CV) and rotating‐disk voltammetry (RDV) showed large cathodic shifts of the first oxidation potentials for some of the chiral and achiral [AB]‐type oligomers due to sterically enforced π‐deconjugation of the acceptor and donor moieties. The new multivalent systems feature intense, bathochromically shifted intramolecular charge‐transfer (CT) bands in the UV/Vis spectra. Extended, donor‐substituted TCBDs, which are obtained by mono‐addition of TCNE to the hexaynes, exhibit low optical and electrochemical HOMO–LUMO gaps. In addition, a large third‐order optical nonlinearity was measured for one of these TCBDs by degenerate four‐wave mixing (DFWM).
Asymmetric Synthesis of (1,3‐Butadien‐2‐yl)methanols from Aldehydes via [1‐(Silylmethyl)allenyl]methanols
Authors: Durán‐Galván María , Connell Brian T. 
Published: March 2010

Abstract[1‐(Silylmethyl)allenyl]methanols 2 were efficiently synthesized from aldehydes and (4‐bromobut‐2‐ynyl)trimethylsilane in the presence of a catalytic amount of CrCl2 and tridentate carbazole ligands. The desired compounds were obtained with good yields (43–88 %) and enantioselectivities (55–78 % ee). Alcohols 2 may be treated with TBAF or 2 M HCl in the case of aliphatic substrates, to provide (1,3‐butadien‐2‐yl)methanols 3 in 43–81 % yields. This method allows the synthesis of dienes 3 with no regioselectivity problems, and it tolerates a large number of functionalities.
Particle trapping using dielectrophoretically patterned carbon nanotubes
Authors: Khoshmanesh Khashayar , Zhang Chen , Nahavandi Saeid , Tovar‐Lopez Francisco J. , Baratchi Sara , Hu Zheng , Mitchell Arnan , Kalantar‐zadeh Kourosh 
Published: March 2010

AbstractThis study presents the dielectrophoretic (DEP) assembly of multi‐walled carbon nanotubes (MWCNTs) between curved microelectrodes for the purpose of trapping polystyrene microparticles within a microfluidic system. Under normal conditions, polystyrene particles exhibit negative DEP behaviour and are repelled from microelectrodes. Interestingly, the addition of MWCNTs to the system alters this situation in two ways: first, they coat the surface of particles and change their dielectric properties to exhibit positive DEP behaviour; second, the assembled MWCNTs are highly conductive and after the deposition serve as extensions to the microelectrodes. They establish an array of nanoelectrodes that initiates from the edge of microelectrodes and grow along the electric field lines. These nanoelectrodes can effectively trap the MWCNT‐coated particles, since they cover a large portion of the microchannel bottom surface and also create a much stronger electric field than the primary microelectrodes as confirmed by our numerical simulations. We will show that the presence of MWCNT significantly changes performance of the system, which is investigated by trapping sample polystyrene particles with plain, COOH and goat anti‐mouse IgG surfaces.
Measurements of acid volatile sulfide and simultaneously extracted metals are irreproducible among laboratories
Authors: Hammerschmidt Chad R. , Burton G. Allen 
Published: March 2010

AbstractPartitioning with solid phases is a principal control on availability and associated toxicity of metals to aquatic biota. In anoxic sediments, environmentally active fractions of sulfide and associated metals are defined operationally as acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM). Ratios of these chemical parameters are often used in establishing equilibrium partitioning sediment benchmarks for toxicity and, therefore, require analytical accuracy to be useful. To investigate the reproducibility and accuracy of AVS and SEM measurements, we distributed subsamples of four physicochemically disparate stream sediments to seven independent laboratories, including our own, for analysis of both AVS and SEM (Cd, Cu, Pb, Ni, and Zn). Synthesis of these results shows that AVS varied from 70 to 3,500× and SEM ranged from 17 to 60× among laboratories for each of the four sediments. Inadequate detection limits for AVS precluded calculation of SEM:AVS ratios for two of the deposits, whereas the ratio varied more than 50-fold among laboratories for the other two sediments. This work highlights the need for improved quality control and standardization of methods for determination of AVS and SEM in sediments, and suggests that predictions of metal toxicity in sediments can be laboratory specific, which raises concerns on the use of the AVS:SEM model for risk assessments and regulatory decisions. Environ. Toxicol. Chem. 2010;29:1453–1456. © 2010 SETAC
Relating the ability of mallards to ingest high levels of sediment to potential contaminant exposure in waterfowl
Authors: Heinz Gary H. , Beyer W. Nelson , Hoffman David J. , Audet Daniel J. 
Published: March 2010

Abstract
When waterfowl feed from the bottom of bodies of water, they sometimes ingest sediments along with their food, and this sediment can be a major source of contaminants. Learning how much sediment waterfowl can consume in their diet and still maintain their health would be helpful in assessing potential threats from contaminants in sediment. In a controlled laboratory study the maximum tolerated percentage of sediment in the diet of mallards (Anas platyrhynchos) was measured. When fed a well-balanced commercial avian diet, 50, 60, or 70% sediment in the diet on a dry-weight basis did not cause weight loss over a two-week period. Ducks fed this same commercial diet, but containing 80 or 90% sediment, lost 8.6 and 15.6% of their body weight, respectively, in the first week on those diets. After factoring in the ability of the mallards to sieve out some of the sediment from their diet before swallowing it, we concluded that the mallards could maintain their health even when approximately half of what they swallowed, on a dry-weight basis, was sediment. Environ. Toxicol. Chem. 2010;29:1621–1624. © 2010 SETAC
Dioxin transfer from sediment to the infaunal surface deposit-feeding polychaetePerinereis nuntiain a laboratory-rearing experiment
Authors: Kono Kumiko , Tanaka Hiroyuki , Koyama Jiro 
Published: March 2010

AbstractIn the presented study a laboratory experiment was conducted to investigate the transfer of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) from environmentally contaminated marine sediment to an infaunal surface deposit-feeding polychaete, Perinereis nuntia. Polychaetes were exposed to contaminated sediment for 42 d, and elimination of these compounds was studied for an additional 28 d. The sediment uptake rate coefficients (ks), elimination rate constants (k2), and the biota-sediment accumulation factors (BSAFs) were determined for PCDDs, PCDFs (PCDD/Fs), and dioxin-like PCBs. Each of these compounds was transferred from sediment to polychaete except for hepta- and octachlorinated PCDD/Fs. The BSAFs for dioxin-like PCBs (0.13–2.2) were significantly higher than those for PCDD/Fs (0.00022–0.36). The BSAF, ks, and k2 values obtained in the present study indicate that the bioaccumulation characteristics of PCDD/Fs in polychaete are similar to those in fish, and depend on their physical and chemical properties such as hydrophobicity and size of molecules. The ks values for PCDD/Fs and dioxin-like PCBs declined with an increase in their log KOW values, indicating a decrease in bioavailability. The negative exponential relationships of k2 versus KOW were observed for these compounds. The slope for the log-normalized regression of k2 versus KOW for the PCDD/Fs was smaller than that for the dioxin-like PCBs and that of ks versus KOW for the PCDD/Fs. Therefore, the negative exponential relationship of BSAF versus KOW was observed for PCDD/Fs, but not for dioxin-like PCBs. Environ. Toxicol. Chem. 2010;29:1512–1519. © 2010 SETAC
Stress response of heavy metal mixture present in wastewater and leachate on heat-shock protein 47-transfected cells
Authors: Fredj Fahmi Ben , Irie Mitsuteru , Han Junkyu , Yamada Parida , Limam Atef , Ghrabi Ahmed , Morio Takahiro , Isoda Hiroko 
Published: March 2010

Abstract
Heavy metals present in water environment and hazardous sites as single compounds or mixture may drastically affect human health. In the present work, we investigated the risk assessment of wastewater effluents and leachate with a focus on three heavy metals—nickel (Ni), cadmium (Cd), and lead (Pb)—and their combined effect on mammalian cells, using Chinese hamster ovary cells transfected with the heat-shock protein (HSP) 47 promoter. The heavy metal mixture model was designed based on the concentrations of metals in wastewater effluents and leachate sampled in Tunisia. Using a ternary diagram, we investigated the stress response of the interaction model. This research indicated that the single heavy metals induced the stress response on HSP(+) cells even at concentrations lower than the local and international guidelines. Differences in water quality likely influenced the metal responses such that the organic composition of the leachate increased the stress response induced by the heavy metals exclusively, whereas the effluents included organic compounds that were able to mask the heavy metal effect. The mixture characterization discovered the key role played by the high levels of Ni or combination of Cd and Pb to induce the highest stress response following 3-h incubation. Heat-shock protein 47 has proven its effectiveness for assessing the heavy metal mixture effect even at low concentrations. Furthermore, the combination of a bioassay system with a statistical model proved extremely useful for better understanding the major contributors to the stress response of the mixture. Environ. Toxicol. Chem. 2010;29:1637–1647. © 2010 SETAC
Microbial transformation of isopinocampheol and caryophyllene oxide
Authors: Noma Yoshiaki , Hashimoto Toshihiro , Uehara Shinya , Asakawa Yoshinori 
Published: March 2010

AbstractThe biotransformation of (+)‐isopinocampheol and (−)‐isopinocampheol and (6R)‐(−)‐caryophyllene oxide was carried out by Aspergillus niger TBUYN‐2. A. niger converted (+)‐isopinocampheol to give (+)‐5‐hydroxyisopinocampheol and (+)‐1‐hydroxyisopinocampheol. On the other hand, (−)‐isopinocampheol was converted to (−)‐5‐hydroxyisopinocampheol, (−)‐1‐hydroxyisopinocampheol and (+)‐2‐hydroxyisopinocampheol. In the case of (6R)‐(−)‐caryophyllene oxide, (−)‐caryophyllene‐12‐oic acid and (−)‐caryophyllene‐6,7,12‐triol were obtained as new compounds. Clovandiol, which is a component of Salvia canariensis, was also obtained from (6R)‐(−)‐caryophyllene oxide following incubation for 4 days with shaking in medium without microorganisms. Copyright © 2010 John Wiley & Sons, Ltd.