bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precipitation of filamentous bacteriophages for their selective recovery in primary purification
Authors: Branston Steven , Stanley Emma , Keshavarz‐Moore Eli , Ward John 
Published: August 2011

AbstractFilamentous bacteriophages and their derivatives are showing great promise as a whole new class of industrial agents, such as biologically based nano‐materials and viral vectors. This raises challenges for their large‐scale manufacture, principally due to the lack of bioprocessing knowledge. This article addresses what will be a potentially important option in the primary purification of the bacteriophages. Polyethylene glycol (PEG)‐salt dual precipitants, calcium ions, spermidine, and isoelectric precipitation were first examined for their potential suitability for bacteriophage concentration under both pure and broth conditions. Successful precipitants were further studied on the basis of their selective purification ability from DNA and protein contaminants in a clarified broth system. Both PEG‐based and isoelectric precipitations resulted in bacteriophage purity improvements, and PEG‐based precipitations offered the highest selectivities. This work shows that precipitation of bacteriophages can be an effective primary purification step in a large‐scale bioprocess. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Preparation, characterization, and properties of fullerene–vinylpyrrolidone copolymers
Authors: Jiang Guichang , Li Guangtao 
Published: August 2011

AbstractWater‐soluble fullerene (C60)–N‐vinylpyrrolidone copolymers were prepared by the radical polymerization method. The structures of the copolymers were characterized by Fourier transform infrared, UV–Vis, 1H NMR, 13C NMR, gel permeation chromatography, thermogravimetric analyses, and scanning electron microscopy (SEM). The results presented show that C60 and vinylpyrrolidone (VP) can be copolymerized under different conditions. With a constant benzoyl peroxide amount, C60 contents in the copolymers increase with increasing initial C60:VP reactant ratio. The assembly behavior of water‐soluble C60–N‐vinylpyrrolidone copolymers was investigated by SEM. The results show that the copolymers create morphology that is sphere‐like. Fullerene‐containing micro‐/nano‐sized copolymer fibers were prepared, for the first time, by electrospinning. The cytotoxicity to cancer cell lines of the copolymers was evaluated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide and confocal laser scanning microscope. The results show that copolymers exhibit better cytotoxicity against HeLa cells and mouse osteogenic sarcoma cells (cytotoxicity of copolymers is better than that of fullerene complex). The mechanism of fullerene–VP copolymerization was investigated for the first time. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Spontaneous Crowding of Ribosomes and Proteins inside Vesicles: A Possible Mechanism for the Origin of Cell Metabolism
Authors: Pereira de Souza Tereza , Steiniger Frank , Stano Pasquale , Fahr Alfred , Luisi Pier Luigi 
Published: August 2011

AbstractOne of the open questions in the origin of life is the spontaneous formation of primitive cell‐like compartments from free molecules in solution and membranes. “Metabolism‐first” and “replicator‐first” theories claim that early catalytic cycles first evolved in solution, and became encapsulated inside lipid vesicles later on. “Compartment‐first” theories suggest that metabolism progressively occurred inside compartments. Both views have some weaknesses: the low probability of co‐entrapment of several compounds inside the same compartment, and the need to control nutrient uptake and waste release, respectively. By using lipid vesicles as early‐cell models, we show that ribosomes, proteins and lipids spontaneously self‐organise into cell‐like compartments to achieve high internal concentrations, even when starting from dilute solutions. These findings suggest that the assembly of cell‐like compartments, despite its low probability of occurrence, is indeed a physically realistic process. The spontaneous achievement of high local concentration might provide a rational account for the origin of primitive cellular metabolism.
Galvanic Deposition of Au on Paperlike Cu Fiber for High‐Efficiency, Low‐Temperature Gas‐Phase Oxidation of Alcohols
Authors: Zhao Guofeng , Hu Huanyun , Deng Miaomiao , Lu Yong 
Published: August 2011

AbstractThe highly active and selective gold‐on‐copper fiber catalysts with excellent heat conductivity were successfully prepared for high‐efficiency gas‐phase selective oxidation of various alcohols. The Au/Cu‐fiber catalysts were obtained by conducting galvanic deposition of Au onto a thin‐sheet microfibrous structure that consisted of 5 vol % Cu‐fiber (8 μm diameter), and 95 vol % voidage. The best catalyst was Au‐3/Cu‐fiber‐200 (Au loading: 3 wt %; calcined at 200 °C in air), which was effective for acyclic, benzylic, and polynary alcohols using a high weight hourly space velocity of 20 h−1. Benzyl alcohol conversion of 86 % was obtained with 99 % selectivity to benzaldehyde at 220 °C. Cyclopropanemethanol could be transformed to cyclopropanecarboxaldehyde, with conversion of 91 % and selectivity of 95 % at 250 °C. 1,2‐Propanediol demonstrated a high conversion of 92 %, with a medium selectivity of 74 % at 340 °C. An oxidation of volatile unsaturated alcohols, such as crotyl alcohol and 3‐methyl‐2‐butenol, could also proceed highly selectively with good conversions at 280 °C. A low ΔT of less than 10 °C between the catalyst bed and the external wall of the reactor was observed in the selective oxidation of benzyl alcohol owing to the enhanced heat‐transfer ability that permits rapid dissipation of large quantities of the reaction heat. Special AuCu(alloy)–Cu2O active composites were formed during the reaction, and their cooperative effect contributed to increasing the low‐temperature activity. By nature, the AuCu alloy can catalyze the oxidation of Cu2O–H species with O2 to release active Cu2O sites.
Plasticity of tyrosine hydroxylase and serotonergic systems in the regenerating spinal cord of adult zebrafish
Authors: Kuscha Veronika , Barreiro‐Iglesias Antón , Becker Catherina G. , Becker Thomas 
Published: August 2011

AbstractMonoaminergic innervation of the spinal cord has important modulatory functions for locomotion. Here we performed a quantitative study to determine the plastic changes of tyrosine hydroxylase‐positive (TH1+; mainly dopaminergic), and serotonergic (5‐HT+) terminals and cells during successful spinal cord regeneration in adult zebrafish. TH1+ innervation in the spinal cord is derived from the brain. After spinal cord transection, TH1+ immunoreactivity is completely lost from the caudal spinal cord. Terminal varicosities increase in density rostral to the lesion site compared with unlesioned controls and are re‐established in the caudal spinal cord at 6 weeks post lesion. Interestingly, axons mostly fail to re‐innervate more caudal levels of the spinal cord even after prolonged survival times. However, densities of terminal varicosities correlate with recovery of swimming behavior, which is completely lost again after re‐lesion of the spinal cord. Similar observations were made for terminals derived from descending 5‐HT+ axons from the brain. In addition, spinal 5‐HT+ neurons were newly generated after a lesion and transiently increased in number up to fivefold, which depended in part on hedgehog signaling. Overall, TH1+ and 5‐HT+ innervation is massively altered in the successfully regenerated spinal cord of adult zebrafish. Despite these changes in TH and 5‐HT systems, a remarkable recovery of swimming capability is achieved, suggesting significant plasticity of the adult spinal network during regeneration. J. Comp. Neurol. 520:933–951, 2012. © 2011 Wiley Periodicals, Inc.
Projections from Gudden's tegmental nuclei to the mammillary body region in the cynomolgus monkey (Macaca fascicularis)
Authors: Saunders Richard C. , Vann Seralynne D. , Aggleton John P. 
Published: August 2011

AbstractGudden's tegmental nuclei provide major inputs to the rodent mammillary bodies, where they are thought to be important for learning and navigation. Comparable projections have yet to be described in the primate brain, where part of the problem has been in effectively delineating these nuclei. Immunohistochemical staining of tissue from a series of macaque monkeys (Macaca mulatta) showed that cells in the region of both the ventral and dorsal tegmental nuclei selectively stain for parvalbumin, thus helping to reveal these nuclei. These same tegmental nuclei were not selectively revealed when tissue was stained for SMI32, acetylcholinesterase, calbindin, or calretinin. In a parallel study, horseradish peroxidase was injected into the mammillary bodies of five cynomolgus monkeys (Macaca fascicularis). Retrogradely labeled neurons were consistently found in the three subdivisions of the ventral tegmental nucleus of Gudden, which are located immediately below, within, and above the medial longitudinal fasciculus. Further projections to the mammillary body region arose from cells in the anterior tegmental nucleus, which appears to be a rostral continuation of the infrafascicular part of the ventral tegmental nucleus. In the dorsal tegmental nucleus of Gudden, labeled cells were most evident when the tracer injection was more laterally placed in the mammillary bodies, consistent with a projection to the lateral mammillary nucleus. The present study not only demonstrates that the primate mammillary bodies receive parallel inputs from the dorsal and ventral tegmental nuclei of Gudden, but also helps to confirm the extent of these poorly distinguished nuclei in the monkey brain. J. Comp. Neurol. 520:1128–1145, 2012. © 2011 Wiley Periodicals, Inc.
Modeling a semi‐flexible filament in cellular Stokes flow using regularized Stokeslets
Authors: Bouzarth Elizabeth L. , Layton Anita T. , Young Yuan‐Nan 
Published: August 2011

SUMMARYMany physical and biological systems involve inextensible fibers immersed in a fluid; examples include cilia, polymer suspensions, and actin filament transport. In such systems, the dynamics of the immersed fibers may play a significant role in the observed macroscale fluid dynamics. In this study, we simulate the dynamics of an approximately inextensible semi‐flexible fiber immersed in a two‐dimensional cellular background flow. The system is modeled as an immersed boundary problem with the fluid dynamics described using the Stokes equations. The motion of the immersed fiber is computed by means of the method of regularized Stokeslets, which allows one to calculate fluid velocity, pressure, and stress in the Stokes fluid flow regime because of a collection of regularized point forces without computing fluid velocities on an underlying grid. Simulation results show that, for some parameter values, the fiber may buckle when approaching a stagnation point. These results provide insight into the stretch–coil transition and macroscale random walk behavior that have been reported in mathematical and experimental literature. Copyright © 2011 John Wiley & Sons, Ltd.
Effects of the Nature and Length of the π‐Conjugated Bridge on the Second‐Order Nonlinear Optical Responses of Push–Pull Molecules Including 4,5‐Dicyanoimidazole and Their Protonated Forms
Authors: Plaquet Aurélie , Champagne Benoît , Kulhánek Jiří , Bureš Filip , Bogdan Elena , Castet Frédéric , Ducasse Laurent , Rodriguez Vincent 
Published: August 2011

AbstractTheoretical and experimental methods of characterization have been employed to investigate a series of six push–pull molecules containing a 4,5‐dicyanoimidazole acceptor (A) unit, a N,N‐dimethylamino donor (D) group, and systematically enlarged π‐conjugated linkers (π) with the view of assessing their first hyperpolarizabilities (β) as well as their variations upon protonation. The results demonstrated that protonation occurred at the N,N‐dimethylamino function, which led to disruption of the electronic charge‐transfer delocalization: the A–π–D pattern of the neutral species with large β values was transformed into an A–π–A′ pattern, which displayed much smaller β values. This feature makes these systems applicable as pH‐triggered nonlinear optics (NLO) switches. In particular, protonation led to a decrease of the hyper‐Rayleigh scattering first hyperpolarizabilities by at least one order of magnitude as well as to a decrease of the depolarization ratio, from about five for neutral species, which also supported the 1D‐like NLO‐phore nature, to about two for the protonated ones.
Optical Sensing of Current Dynamics in Organic Light‐Emitting Devices at the Nanometer Scale
Authors: Nothaft Maximilian , Höhla Steffen , Nicolet Aurélien , Jelezko Fedor , Frühauf Norbert , Pflaum Jens , Wrachtrup Jörg 
Published: August 2011

AbstractPhotoluminescence quenching of single dibenzoterrylene (DBT) dye molecules in a polymeric organic light‐emitting diode was utilized to analyze the current dynamics at nanometer resolution. The quenching mechanism of single DBT molecules results from an increase in the triplet‐state population induced by charge carrier recombination on individual guest molecules. As a consequence of the long triplet‐state relaxation time, its population results in a reduced photoluminescence of the dispersed fluorescent dyes. From the decrease in photoluminescence together with photon correlation measurements, we could quantify the local current density and its time‐dependent evolution in the vicinity of the single‐molecule probe. This optical technique establishes a non‐invasive approach to map the time‐resolved current density in organic light‐emitting diodes on the nanometer scale.
Iron‐Based Superconductors with Extended FeX4 (X = As and Se) Tetrahedra
Authors: Ganguli Ashok K. , Prakash Jai 
Published: August 2011

AbstractIntermetallic compounds have been investigated over several decades for their interesting structural and physical properties, including magnetism and superconductivity. Among these, metal pnictides and chalcogenides of transition metals show diversity of bonding ranging from appreciable covalency to metal–metal bonds, which makes these compounds highly complex. ZrCuSiAs and ThCr2Si2 are of interest, because they provide an opportunity to design interesting intermetallics with tetrahedral layers exhibiting quasi‐two‐dimensional behavior. However, these metal pnictides and chalcogenides were not well known for their superconducting properties. The recent discovery of superconductivity at 26 K in a ZrCuSiAs‐related structure (LaO/FFeAs) created huge excitement in the field of metal pnictide and chalcogenide superconductors. The role of the FeX4 tetrahedra is significant for superconductivity. Distortion of the tetrahedra lowers the superconducting transition temperature (Tc) in these Fe‐based superconductors. This article discusses the structural aspects of various new (2008–2011) families of Fe‐based superconductors containing FeX4 tetrahedra (X = As and Se) that act as charge carrier layers in these superconductors.
Synthesis and Structural Diversity of Mono‐, Di‐ and Trinuclear Complexes with N,N′‐Bis[(2‐diphenylphosphanyl)phenyl]formamidine
Authors: Son Kyung‐sun , Pearson David M. , Jeon Sang‐Jin , Waymouth Robert M. 
Published: August 2011

AbstractThe synthesis, characterization, and coordination chemistry of a series of mono‐, di‐, and trinuclear homo‐/heterometallic complexes with the dinucleating ligand, N,N′‐bis[(2‐diphenyl‐phosphanyl)phenyl]formamidine (pnnp)1 are reported. Treatment of (pnnp)PdMe (1) with NiCl2(dme) forms the heterobimetallic (pnnp)PdMe(μ‐Cl)NiCl (3) complex, whereas reaction of 1 with Cu(CH3CN)4+PF6– yields the Pd···Cu···Pd heterometallic trinuclear complex (pnnp)Pd(Me)CuPd(Me)(pnnp)·PF6 (8). The reaction of pnnp with NiCl2(dme) (dme = 1,2‐dimethoxyethane) produces the Ni dimer [(pnnp)NiCl(μ‐Cl)]2 (5) or the dinuclear (pnnp)NiCl(μ‐X)NiCl (X = Cl or OH) (4) complexes, depending upon the stoichiometry. The reaction of pnnp with CoII or FeII ions leads to the monometallic complexes (pnnp)CoCl2 (6) or (pnnp)FeCl2 (7), respectively. The dinuclear (pnnp)PdMe(μ‐Cl)NiCl (3) and (pnnp)NiCl(μ‐X)NiCl (X = Cl or OH) (4) complexes adopt A‐frame structures with two square‐planar d8 metal complexes hinged by the bridging ligand; the angles between the square planes correlate to the covalent radii, in which the smaller homo‐bimetallic Ni complex adopts a more coplanar arrangement of the two Ni square planes. The heterometallic trinuclear complex (pnnp)Pd(Me)CuPd(Me)(pnnp)·PF6 (8) adopts an unusual structure around the Cu center, suggestive of a weak d8–d10 interaction between the Pd and Cu atoms. All complexes have been characterized by NMR spectroscopy, elemental analysis, and X‐ray crystallography, and their structural diversity is discussed.
A Dy6 Cluster Displays Slow Magnetic Relaxation with an Edge‐to‐Edge Arrangement of Two Dy3 Triangles
Authors: Ke Hongshan , Zhao Lang , Guo Yang , Tang Jinkui 
Published: August 2011

AbstractA new dysprosium(III) cluster, namely [Dy6III(L)4(μ3‐OH)4(CH3OH)2(NO3)2]·6CH3CN (1), has been synthesized from the Schiff base ligand 1,3‐bis(salicylideneamino)‐2‐propanol and dysprosium nitrate. A single‐crystal X‐ray diffraction study reveals that the core of 1 consists of an edge‐to‐edge arrangement of two Dy3 triangles. Both static (dc) and dynamic (ac) magnetic properties of 1 have been studied. The results show that slow magnetic relaxation is operating in compound 1.
Intrapopulation Variability in the Terpene Metabolism of the Antarctic Opisthobranch Mollusc Austrodoris kerguelenensis
Authors: Cutignano Adele , Zhang Wen , Avila Conxita , Cimino Guido , Fontana Angelo 
Published: August 2011

AbstractAustrodoris kerguelenensis is an Antarctic marine mollusc possessing a wide array of deterrent terpene glycerides. The occurrence of these compounds has been studied in individuals of a sample of 21 specimens from two different geographical sites. NMR spectroscopy and liquid chromatography (LC)–MS/MS analysis revealed seven glycerides (1–7) based on four diterpene skeletons in these animals. Among the new compounds 4–7, the glyceride 7 shows a rare 9‐epi‐labdane skeleton. The interindividual variability of these compounds indicates several chemotypes in the same population and suggests the presence of terpene synthase variants involved in the biosynthesis of these defensive molecules.
Diastereoselective Access to Tri‐ and Pentacyclic Spiro‐γ‐lactam‐oxindole Cores through a Tandem Aza‐Michael Initiated Ring Closure Sequence
Authors: Allous Iyad , Comesse Sébastien , Sanselme Morgane , Daïch Adam 
Published: August 2011

AbstractHerein, we present a new development of the previously described aza‐Michael‐initiated ring closure (MIRC) process to access spirooxindole cores. The key spiro‐cyclization step between various α‐bromoacetamides and methyleneindolinones was efficient and tolerant of a wide range of functional groups. Yields and diastereoselectivities for the spirocyclization were usually high and furnished original spiro[oxindole‐3,3′‐γ‐lactam] derivatives. The utility of these novel building blocks for the preparation of more sophisticated derivatives was demonstrated by the preparation of four pentacyclic spirooxindoles.
Mars Global Digital Dune Database (MGD3): north polar region (MC‐1) distribution, applications, and volume estimates
Authors: Hayward Rosalyn K. 
Published: August 2011

ABSTRACTThe Mars Global Digital Dune Database (MGD3) now extends from 90°N to 65°S. The recently released north polar portion (MC‐1) of MGD3 adds ~844 000 km2 of moderate‐ to large‐size dark dunes to the previously released equatorial portion (MC‐2 to MC‐29) of the database. The database, available in GIS‐ and tabular‐format in USGS Open‐File Reports, makes it possible to examine global dune distribution patterns and to compare dunes with other global data sets (e.g. atmospheric models). MGD3 can also be used by researchers to identify areas suitable for more focused studies. The utility of MGD3 is demonstrated through three example applications. First, the uneven geographic distribution of the dunes is discussed and described. Second, dune‐derived wind direction and its role as ground truth for atmospheric models is reviewed. Comparisons between dune‐derived winds and global and mesoscale atmospheric models suggest that local topography may have an important influence on dune‐forming winds. Third, the methods used here to estimate north polar dune volume are presented and these methods and estimates (1130 km3 to 3250 km3) are compared with those of previous researchers (1158 km3 to 15 000 km3). In the near future, MGD3 will be extended to include the south polar region. Published in 2011. This article is a US Government work and is in the public domain in the USA.
Purinergic signaling in the cerebellum: Bergmann glial cells express functional ionotropic P2X7 receptors
Authors: Habbas Samia , Ango Fabrice , Daniel Hervé , Galante Micaela 
Published: August 2011

AbstractAstrocytes constitute active networks of intercommunicating cells that support the metabolism and the development of neurons and affect synaptic functions via multiple pathways. ATP is one of the major neurotransmitters mediating signaling between neurons and astrocytes. Potentially acting through both purinergic metabotropic P2Y receptors (P2YRs) and ionotropic P2X receptors (P2XRs), up until now ATP has only been shown to activate P2YRs in Bergmann cells, the radial glia of the cerebellar cortex that envelopes Purkinje cell afferent synapses. In this study, using multiple experimental approaches in acute cerebellar slices we demonstrate the existence of functional P2XRs on Bergmann cells. In particular, we show here that Bergmann cells express uniquely P2X7R subtypes: (i) immunohistochemical analysis revealed the presence of P2X7Rs on Bergmann cell processes, (ii) in whole cell recordings P2XR pharmacological agonists induced depolarizing currents that were blocked by specific antagonists of P2X7Rs, and could not be elicited in slices from P2X7R‐deficient mice and finally, (iii) calcium imaging experiments revealed two distinct calcium signals triggered by application of exogenous ATP: a transient signal deriving from release of calcium from intracellular stores, and a persistent one following activation of P2X7Rs. Our data thus reveal a new pathway by which extracellular ATP may affect glial cell function, thus broadening our knowledge on purinergic signaling in the cerebellum. © 2011 Wiley‐Liss, Inc.