bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of a gas‐liquid OBC: Bubble size and gas holdup
Authors: Oliveira Mónica S. N. , Ni Xiong‐Wei 
Published: November 2004

AbstractA fundamental experimental study of gas‐liquid contacting in an oscillatory baffled column is presented focusing on the effect of fluid oscillation on gas holdup and bubble size. The results show that beyond a critical level of fluid oscillation the Sauter mean diameter of the dispersion is substantially reduced, while the gas holdup (and, thus, the residence time of the gas phase) increases significantly. The reduction of bubble size was described in terms of bubble breakage, caused by the interaction of the bubbles with eddies. The experimental results were modeled by applying Kolmogoroff's theory of isotropic turbulence. The steep increase in the gas holdup with oscillation was mainly due to bubble entrainment by large vortices, formed by the oscillatory flow in the presence of baffles. A semi‐theoretical expression, based on the forces acting on a bubble, was proposed, and was able to accurately match the experimental trends. The results also show that the gas‐liquid hydrodynamics are mainly governed by the oscillatory operating conditions, and independent of the type of gas sparger. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3019–3033, 2004
Fast and reliable sexing of prosimian and human DNA
Authors: Fredsted T. , Villessen P. 
Published: November 2004

AbstractMolecular sexing of mammals is normally done by PCR amplification of Y chromosomal fragments, or coamplification of homologous fragments from both sex chromosomes. Existing primers are often unreliable for distantly related species due to mutations in primer regions. Currently there are no published primers for the sexing of prosimian DNA. We show that an existing method (using the zinc finger protein) based on a size difference between the X and Y homologs does not work in prosimians. Multiple alignments of distantly related mammalian species from Genbank and genome databases enabled us to identify conserved regions in the amelogenin gene. Using these conserved regions, we can target species that have no sequence information. We designed a single, conserved primer pair that is useful for fast and reliable molecular sexing of prosimian primates. A single PCR yields two fragments in males and only one in females, which are easily separated with the use of agarose gels. Amplification of separable fragments was successful in seven species of lemurs, as well as humans. Am. J. Primatol. 64:345–350, 2004. © 2004 Wiley‐Liss, Inc.
Agonistic behavior and dominance relationships in female phayre's leaf monkeys – preliminary results
Authors: Koenig Andreas , Larney Eileen , Lu Amy , Borries Carola 
Published: November 2004

AbstractSocioecological theory suggests a link between the strength of competition for food/safety, rates of agonism, structure of dominance hierarchies, and dispersal among group‐living females. This study presents preliminary data on agonistic behavior and dominance relationships for female Phayre's leaf monkeys (Trachypithecus phayrei), a species in which females routinely disperse. Behavioral observations were conducted on two groups (four adult females, and five adult females plus two juvenile females, respectively) at Phu Khieo Wildlife Sanctuary, northeast Thailand. Rates of agonistic behavior were analyzed from focal continuous recordings, while dominance hierarchies were constructed from all agonistic behaviors (focal and ad libitum sampling). Overall, female–female agonistic behaviors (aggression, submission, and displacements) occurred at a rate of <0.25 interactions per hour. Agonistic interactions involving food occurred more frequently than expected based on feeding time. Females in both groups exhibited linear dominance hierarchies with some reversals, and possibly an age‐inversed hierarchical structure in the larger group. The results fit well with previous results for colobine monkeys regarding frequency of interactions, displacements predominating agonistic behavior, and the possibility of an age‐inversed hierarchy. The results contradict the suggested link between linearity of hierarchies and female philopatry. Future studies should consider the notion that female dispersal may coexist with linear dominance hierarchies. Am. J. Primatol. 64:351–357, 2004. © 2004 Wiley‐Liss, Inc.
DNA‐Codes für die Nanowissenschaften
Authors: Samorì Bruno , Zuccheri Giampaolo 
Published: November 2004

AbstractDer Nanometerbereich ist ein ganz spezieller Ort – treffen sich hier doch alle naturwissenschaftlichen Disziplinen. Die Nanowissenschaften ziehen ihre Ideen aus der Biologie, und Aufgabe der Chemie ist es, diese Ideen in nanotechnologische Anwendungen umzusetzen. Das biologische Molekül, das Nanowissenschaften und Nanotechnik gegenwärtig am meisten fasziniert, ist die DNA. Die Natur nutzt die DNA nicht nur als “Ablage” für die genetische Information, sondern auch als Steuerungseinheit für die Expression der darin enthaltenen Gene. So enthält die DNA‐Sequenz bestimmte Codes, die atomare Erkennungsprozesse wie etwa die Basenpaarung steuern, und andere, die Prozesse im Nanometerbereich kontrollieren. Aus chemischer Sicht ist die DNA die supramolekulare Baueinheit mit dem größten bekannten Informationsgehalt. Für die Nanowissenschaften ergibt sich daraus die Möglichkeit, mit DNA‐Molekülen das Komplexitätsniveau und die Effizienz bei Selbstorganisations‐ und Selbstausrichtungsprozessen zu steigern.
Integrated Nanoparticle–Biomolecule Hybrid Systems: Synthesis, Properties, and Applications
Authors: Katz Eugenii , Willner Itamar 
Published: November 2004

AbstractNanomaterials, such as metal or semiconductor nanoparticles and nanorods, exhibit similar dimensions to those of biomolecules, such as proteins (enzymes, antigens, antibodies) or DNA. The integration of nanoparticles, which exhibit unique electronic, photonic, and catalytic properties, with biomaterials, which display unique recognition, catalytic, and inhibition properties, yields novel hybrid nanobiomaterials of synergetic properties and functions. This review describes recent advances in the synthesis of biomolecule–nanoparticle/nanorod hybrid systems and the application of such assemblies in the generation of 2D and 3D ordered structures in solutions and on surfaces. Particular emphasis is directed to the use of biomolecule–nanoparticle (metallic or semiconductive) assemblies for bioanalytical applications and for the fabrication of bioelectronic devices.
New and highly efficient method for silkworm transgenesis using Autographa californica nucleopolyhedrovirus and piggyBac transposable elements
Authors: Yamamoto Masafumi , Yamao Masafumi , Nishiyama Hiroshi , Sugihara Shinya , Nagaoka Sumiharu , Tomita Masahiro , Yoshizato Katsutoshi , Tamura Toshiki , Mori Hajime 
Published: November 2004

AbstractWe have developed a new method for the transgenesis of the silkworm, Bombyx mori. This method couples the use of recombinant baculoviruses with the use of the piggyBac transposable element. One recombinant AcNPV, designated the helper virus, is designed to express the piggyBac transposase under the control of the Drosophila hsp70 promoter. Another recombinant AcNPV encoded the gene to be incorporated into the silkworm genome, in this case a green fluorescent protein (GFP) gene, under the control of B. mori actin A3 promoter and franked by the piggyBac inverted terminal repeats. Preblastoderm eggs were inoculated with a fine needle coated with a mixture of these two recombinant baculoviruses. Most of the inoculated larvae hatched and a high proportion of the newly hatched G0 larvae expressed the GFP marker. Transgenesis was confirmed by Southern blot analysis of G1 insects, sequencing the insertion site junctions isolated by inverse PCR, and the marker segregated in Mendelian fashion, as evidenced by the appearance of green fluorescence in G2 insects. Thus, transgenic silkworms were easily and efficiently obtained using this new method. © 2004 Wiley Periodicals, Inc.
Synthesis and Characterization of Nanocast Silica NCS‐1 with CMK‐3 as a Template
Authors: Lu An‐Hui , Schmidt Wolfgang , Spliethoff Bernd , Schüth Ferdi 
Published: November 2004

AbstractNanocast silica (NCS‐1) was synthesized by a casting process by employing the mesoporous carbon CMK‐3 (the replica of SBA‐15) as a template, tetraethoxysilane (TEOS) as the silica source, and hydrochloric acid (HCl) as the catalyst. The ordered carbon template was removed by employing different methods, such as calcination, thermal treatment followed by calcination, and controlled combustion. According to XRD and TEM characterization, NCS‐1 exhibits an ordered structure with hexagonal symmetry and retains the morphology of the original SBA‐15 used for the synthesis of CMK‐3 over two replication steps on the nanometer scale. This demonstrates the well‐connected porosity in CMK‐3 type carbon, which can be used as a mold to synthesize mesostructured materials. The nitrogen adsorption isotherms generally show type IV shape, indicating mesoporous characteristics. The structure of NCS‐1 is strongly influenced by variables of the nanocasting process, such as the loading amount of silica, hydrolysis temperature, and carbon removal methods. The surface area, pore size, and pore volume of NCS‐1 can be tuned to a certain range by varying these parameters.
Synthesis, Spectroscopy, and Electrochemistry of Tetra‐tert‐butylated Tetraazaporphyrins, Phthalocyanines, Naphthalocyanines, and Anthracocyanines, together with Molecular Orbital Calculations
Authors: Kobayashi Nagao , Nakajima Shin‐ichiro , Ogata Hiroshi , Fukuda Takamitsu 
Published: November 2004

AbstractTetraazaporphyrins (TAPs), phthalocyanines (Pcs), naphthalocyanines (Ncs), and anthracocyanines (Acs) with four tert‐butyl groups attached at similar positions have been synthesized, and their electronic absorption, magnetic circular dichroism (MCD), IR, and voltammetric properties were studied and interpreted with the help of quantum‐mechanical calculations. Through the preparation of a series of compounds with the same number of the same substituent, the effects of the increase in the size of the ring system were clearly derived. The main results may be summarized as follows. 1) The Q band shifts to longer wavelength and its intensity increases, but with decreasing degree of change with increasing molecular size. If the size of the effect of benzene directly fused to the TAP skeleton is set at unity, the effects of the second and third benzene units are roughly 0.8 and 0.5, respectively. 2) The splitting of the Q bands in metal‐free compounds decreases with increasing molecular size, so that the Q bands of H2Nc and H2Ac appear as single bands. 3) The magnitude of the orbital angular momentum of the excited state of the ligand decreases with increasing molecular size. 4) Interestingly, the ring current, as judged from the positions of pyrrole proton signals in the 1H NMR spectrum, appears to decrease with increasing molecular size. 5) The first reduction potential becomes less negative, but only slightly, whereas the first oxidation potential shows a marked shift to less positive values with increasing molecular size, indicating that the HOMO destabilizes significantly as the molecule becomes larger. 6) In 5), the extent of the HOMO destabilization with molecular size differs depending on the central metal, so metals producing smaller destabilization effects can allow larger macrocycles. Of the metals studied, the most effective is cobalt, and the practical size limit is represented by the Acs. 7) The IR spectra become simpler the larger the molecule, and the main bands were assigned by DFT calculations. 8) The trend in experimentally determined redox potentials and electronic absorption and MCD spectra were reasonably reproduced by MO calculations using the ZINDO/S Hamiltonian. 9) EPR data for several metallocomplexes are also reported.
cis/trans Photoisomerization of Secondary Thiopeptide Bonds
Authors: Zhao Jianzhang , Micheau Jean‐Claude , Vargas Carolyn , Schiene‐Fischer Cordelia 
Published: November 2004

AbstractThe reversible cis/trans photoisomerization of secondary thiopeptide bonds has been systematically studied with UV‐visible absorption, capillary electrophoresis, 1H NMR spectroscopy, and circular dichroism methods. It was found that the concentration of the cis conformers could be increased from less than 1 % in the thermal equilibrated solution to up to 20 % in the photostationary state. The rotational barriers of the thiopeptide bond and the pH dependence of the isomerization rates were also studied. The quantum yields of the trans→cis and the cis→trans processes were determined from photokinetic analysis.
Mass Spectrometric Investigation of Noncovalent Complexation between a Tetratosylated Resorcarene and Alkyl Ammonium Ions
Authors: Ventola Elina , Rissanen Kari , Vainiotalo Pirjo 
Published: November 2004

AbstractNoncovalent complexation between tetratosylated tetraethyl resorcarene (1) and primary, secondary, and tertiary alkyl ammonium ions (mMe, dMe, tMe, mEt, dEt, tEt, dBu, and dHex) was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI‐FTICR) mass spectrometry. Interactions of the noncovalent complexes were investigated by means of competition experiments, collision‐induced dissociation (CID) experiments, ion–molecule reactions with tripropylamine and gas phase H/D‐exchange reactions with deuteroammonia. Gas phase ion–molecule reactions gave especially valuable information about the structure and properties of the complexes. Resorcarene 1 formed relatively stable 1:1 complexes with all aliphatic alkyl ammonium ions. Steric properties of the alkyl ammonium ions and proton affinities of the conjugate amines noticeably affected the complexation properties, indicating the importance of hydrogen bonding in these complexes. According to the competition experiments, the thermodynamically most stable host–guest complexes were formed with alkyl ammonium ions that were most substituted and had the longest alkyl chains. In CID experiments, release of an intact free guest ion or dissociation of the host was observed to depend on the proton affinity of the amine and the strength of the hydrogen bond that was formed. In ion–molecule reactions with tripropylamine, a guest exchange reaction occurred with all alkyl ammonium ion complexes with reaction rates mostly dependent on the steric properties of the original guest ion. In H/D‐exchange reactions the N‐H hydrogen atoms of the guest ion were exchanged with deuterium, whereas the resorcinol hydrogen atoms remained unchanged.
Solvent‐Ligated Manganese(II) Complexes for the Homopolymerization of Isobutene and the Copolymerization of Isobutene and Isoprene
Authors: Vierle Mario , Zhang Yanmei , Santos Ana M. , Köhler Klaus , Haeßner Carmen , Herdtweck Eberhardt , Bohnenpoll Martin , Nuyken Oskar , Kühn Fritz E. 
Published: November 2004

AbstractPolyisobutenes with a high content of terminal olefinic groups can be synthesized by using manganese(II) initiators in homogeneous solution. These easily accessible complexes initiate the polymerization at room temperature and above, and afford highly reactive, gel‐free polyisobutenes with high viscosities. Furthermore, the initiators were successfully used for the copolymerization of isobutene with isoprene. The high activities of the MnIIinitiators seem to be related to their weakly coordinating nitrile ligands, which are easily displaced by substrate molecules. Replacing the nitrile ligands by other more strongly coordinating ligands such as water reduces the initiator activity significantly. The MnIIinitiators are surprisingly resistant to temperature.
Atmospheric Pressure Chemical Vapor Deposition: An Alternative Route to Large‐Scale MoS2 and WS2 Inorganic Fullerene‐like Nanostructures and Nanoflowers
Authors: Li Xiao‐Lin , Ge Jian‐Ping , Li Ya‐Dong 
Published: November 2004

AbstractLarge‐scale MoS2 and WS2 inorganic fullerene‐like (IF) nanostructures (onionlike nanoparticles, nanotubes) and elegant three‐dimensional nanoflowers (NF) have been selectively prepared through an atmospheric pressure chemical vapor deposition (APCVD) process with the reaction of chlorides and sulfur. The morphologies were controlled by adjusting the deposition position, the deposition temperature, and the flux of the carrier gas. All of the nanostructures have been characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). A reaction mechanism is proposed based on the experimental results. The surface area of MoS2 IF nanoparticles and the field‐emission effect of as‐prepared WS2 nanoflowers is reported.
Palladium‐Catalyzed Intramolecular Oxidative Alkylation of 4‐Pentenyl β‐Dicarbonyl Compounds
Authors: Liu Cong , Wang Xiang , Pei Tao , Widenhoefer Ross A. 
Published: November 2004

AbstractReaction of 8‐nonene‐2,4‐dione with a catalytic amount of [PdCl2(CH3CN)2] (2; 5 mol %) and a stoichiometric amount of CuCl2 (2.5 equiv) at room temperature for 3 h led to oxidative alkylation and formation of 2‐acetyl‐3‐methyl‐2‐cyclohexenone in 80 % isolated yield. The oxidative alkylation of 4‐pentenyl β‐diketones tolerated a number of terminal acyl groups and substitution at the C1 and C3 carbon atoms of the 4‐pentenyl chain. Likewise, 4‐pentenyl β‐keto esters that possessed geminal disubstitution at the C1, C2, or C3 carbon atom of the 4‐pentenyl chain cyclized to form 2‐carboalkoxy‐2‐cyclohexenones in moderate to good yield as the exclusive cyclized product. Deuterium‐labeling experiments provided information regarding the mechanism of the palladium‐catalyzed oxidative alkylation of 4‐pentenyl β‐dicarbonyl compounds.
Synthesis of Benzannulated N‐Heterocyclic Carbene Ligands by a Template Synthesis from 2‐Nitrophenyl Isocyanide
Authors: Hahn F. Ekkehardt , García Plumed César , Münder Marco , Lügger Thomas 
Published: November 2004

AbstractThe reaction of 2‐nitrophenyl isocyanide 2 with [M(CO)5(thf)] (M=Cr, Mo, W) yields the isocyanide complexes [M(CO)5(2)] (3: M=Cr; 4: M=Mo; 5: M=W). Complexes 3–5 react with elemental tin under reduction of the nitro function of the isocyanide ligand to give the complexes with the unstable 2‐aminophenyl isocyanide ligand. The coordinated 2‐aminophenyl isocyanide ligand in all three complexes reacts spontaneously under intramolecular nucleophilic attack of the primary amine at the isocyanide carbon atom to yield the complexes with the NH,NH‐benzimidazol‐2‐ylidene ligand (6: M=Cr; 7: M=Mo; 8: M=W). An incomplete reduction of the nitro group in 3–5 is observed when hydrazine hydrate is used instead of tin. Here the formation of complexes with a coordinated 2‐hydroxylamine‐functionalized phenyl isocyanide [(CO)5M‐CN‐C6H4‐‐2‐N(H)‐OH] is postulated and this unstable ligand again undergoes intramolecular cyclization to give the NH,NOH‐stabilized benzimidazol‐2‐ylidene complexes 9–11. The tungsten derivative 11 can be allylated stepwise by a deprotonation/alkylation sequence first at the OH and then at the NH position to yield the monoallylated and diallylated species 12 and 13. The molecular structures of 3–5 and 12–13 were established by X‐ray crystallography.
A Remarkable Ligand Orientational Effect in Osmium‐Atom‐Induced Blue Phosphorescence
Authors: Yu Jen‐Kan , Hu Ya‐Hui , Cheng Yi‐Ming , Chou Pi‐Tai , Peng Shie‐Ming , Lee Gene‐Hsiang , Carty Arthur J. , Tung Yung‐Liang , Lee Shin‐Wun , Chi Yun , Liu Chao‐Shiuan 
Published: November 2004

AbstractA new series of OsII‐based carbonyl complexes cis(CO),trans(Npy,Npy),cis(Ntz,Ntz)‐[Os(CO)2(bptz)2] (1), cis(CO),cis(Npy,Npy),trans(Ntz,Ntz)‐[Os(bptz)2(CO)2] (2), and cis(CO),trans(Npy,Npy),cis(Ntz,Ntz)‐[Os(CO)2(fptz)2] (3), where bptz and fptz denote 3‐tert‐butyl‐5‐(2‐pyridyl)‐ and 3‐trifluoromethyl‐5‐(2‐pyridyl)‐1,2,4‐triazolate, respectively, have been designed and synthesized in an effort to achieve high efficiency, room‐temperature blue phosphorescence. Although 1 and 2 are geometric isomers, remarkably different excited‐state relaxation pathways were observed. Complex 1 exhibits strong phosphorescence in CH3CN (Φp∼0.47) and as a single crystal at room temperature, whereas complex 2 is nearly nonemissive under similar conditions. The associated relaxation dynamics have been comprehensively investigated by spectroscopic and relaxation dynamics as well as by theoretical approaches. Our results lead us to the conclusion that for complex 2, the “loose bolt” effect of metal–ligand bonding interactions plays a crucial role in the fast radiationless deactivation of this type of geometrical isomer. Fine adjustment can also be achieved by functionalizing the ligands so that the electron‐withdrawing nature of the CF3 group in 3 stabilizes the HOMO of the triazolate moiety, thus moving the emission further into the pure “blue” region; this results in highly efficient phosphorescence and renders 3 particularly attractive for application in blue OLED devices.
Complete Charge Pooling is Prevented in Viologen‐Based Dendrimers by Self‐Protection
Authors: Marchioni Filippo , Venturi Margherita , Ceroni Paola , Balzani Vincenzo , Belohradsky Martin , Elizarov Arkadij M. , Tseng Hsian‐Rong , Stoddart J. Fraser 
Published: November 2004

AbstractWe have investigated the electrochemical behavior, and chemical and photosensitized reduction of two dendrimers based on a 1,3,5‐trisubstituted benzenoid core, which contain 9 and 21 4,4′‐bipyridinium (usually called viologen) units, respectively, in their branches and are terminated with tetraarylmethane groups. For comparison purposes, the behavior of reference compounds that contain a single viologen unit have also been investigated. We have found that only part of the viologen units can be reduced in the dendrimer species. For the larger dendrimer, the number of reducible viologens (out of the 21 present) is 14 in electrochemical experiments (in MeCN), 9 on reduction with bis(benzene)chromium (in MeCN), and 13 by photoinduced electron transfer with 9‐methylanthracene as a photosensitizer and triethanolamine as a sacrificial reductant in CH2Cl2. The reduced viologen units undergo partial dimerization. The photochemical experiments have shown that only monomeric, one‐electron‐reduced viologen units are formed at the beginning of the irradiation, followed by dimer formation, until a photostationary state is reached that contains 40 % nonreduced, 33 % monomeric reduced, and 27 % reduced units associated in the dimeric form. The results suggest that, upon reduction of a fraction of the viologen units, the dendrimer structure shrinks, with the result that the bulky terminal groups protect other viologen units from being reduced.
Synthesis of Branched Oxime‐Linked Peptide Mimetics of the MUC1 Containing a Universal T‐Helper Epitope
Authors: Cremer Gaëlle‐Anne , Bureaud Nicole , Lelièvre Dominique , Piller Véronique , Piller Friedrich , Delmas Agnès 
Published: November 2004

AbstractOur goal was to develop mimics of MUC1, highly immunogenic to induce an efficient immune response against the tumor‐associated form of MUC1, and sufficiently different from the natural antigen to bypass the tolerance barrier in humans. With the aim of obtaining a well‐defined peptide construct as a means of evoking the precise immune responses required in immunotherapy, we synthesized artificial mimics of the MUC1 protein composed of two MUC1 repeat units of inverse orientation and a universal T‐helper epitope. To synthesize these heteromeric peptide constructs, we followed a convergent approach using chemoselective ligation based on oxime chemistry. A stem peptide was first synthesized bearing two orthogonally masked aldehydes. After successive deprotection, two oxime bonds can be specifically generated. The proposed strategy proved to be concise and robust, and allowed the synthesis of the tri‐branched protein in a very satisfactory yield. The different constructs were tested for their ability to generate antibodies able to recognize the MUC1 protein.