bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Phenyl‐1‐benzoxepinols from Butcher's Broom (Rusci rhizoma)
Authors: Barbič Matej , Schmidt Thomas J. , Jürgenliemk Guido 
Published: June 2012

AbstractTwo novel compounds, (3S)‐2,3‐dihydro‐3‐(4‐hydroxyphenyl)‐1‐benzoxepin‐8‐ol (1; ruscozepine A) and (3S)‐2,3‐dihydro‐3‐(4‐hydroxyphenyl)‐8‐methoxy‐1‐benzoxepin‐7‐ol (2; ruscozepine B) were isolated from butcher's broom (Rusci rhizoma) together with a biosynthetically possible phenylethanoid precursor, hydroxytyrosol (3). The structures were elucidated by spectroscopic methods such as 1D‐ and 2D‐NMR (COSY, HSQC, HMBC, ROESY), and HR‐EI‐MS experiments. The absolute configuration of the ruscozepines was determined by electronic circular dichroism.
Sesquiterpenes and Cyclopeptides from the Endophytic Fungus Trichoderma asperellumSamuels, Lieckf. & Nirenberg
Authors: Ding Gang , Chen Amanda Juan , Lan Jin , Zhang Hongwu , Chen Xiangdong , Liu Xingzhong , Zou Zhongmei 
Published: June 2012

AbstractTrichodones A–C (1–3, resp.), three new sesquiterpenes, together with the two known cyclopeptides PF1022F and halobacillin (4 and 5, resp.), have been isolated from the crude extract of the endophytic fungus Trichoderma asperellum Samuels, Lieckf. & Nirenberg residing in the traditional Chinese medicinal plant Panax notoginseng (Burkill) F.H.Chen. The structures and configurations of compounds 1–3 were determined by NMR spectroscopy and mass spectrometry. The relative configuration for 1 was determined by analysis of its pertinent coupling constants and NOESY correlations, whereas the absolute configuration of 1 was established by CD spectroscopy. Compounds 4 and 5 displayed antibacterial activities against Enterococcus faecium (CGMCC 1.2025) with IC50 values of 7.30 and 5.24 μm, and against Staphylococcus aureus COL (CGMCC 1.2465) with IC50 values of 19.02 and 14.00 μM, respectively.
Anti‐Inflammatory and Anti‐Tumor‐Promoting Effects of 5‐Deprenyllupulonol C and Other Compounds from Hop (Humulus lupulus L.)
Authors: Akazawa Hiroyuki , Kohno Hideki , Tokuda Harukuni , Suzuki Nobutaka , Yasukawa Ken , Kimura Yumiko , Manosroi Aranya , Manosroi Jiradej , Akihisa Toshihiro 
Published: June 2012

AbstractA new phloroglucinol derivative, 5‐deprenyllupulonol C (1), along with four other phloroglucinol derivatives, 2–5, five chalcones, 6–10, four flavanones, 11–14, two flavonol glycosides, 15 and 16, and five triterpenoids, 17–21, were isolated from the female inflorescence pellet extracts of hop (Humulus lupulus L.). Upon evaluation of these compounds against the EpsteinBarr virus early antigen (EBV‐EA) activation induced by 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) in Raji cells, twelve compounds, i.e., 1–4, 11–14, 17–19, and 21, showed potent inhibitory effects on EBV‐EA induction, with IC50 values in the range of 215–393 mol ratio/32 pmol TPA. In addition, eleven compounds, i.e., 1–4, 6, 11, 12, 14, 17, 18, and 20, were found to inhibit TPA‐induced inflammation (1 μg/ear) in mice, with ID50 values in the range of 0.13–1.06 μmol per ear. Further, lupulone C (2) and 6‐prenylnaringenin (14) exhibited inhibitory effects on skin‐tumor promotion in an in vivo two‐stage mouse‐skin carcinogenesis test based on 7,12‐dimethylbenz[a]anthracene (DMBA) as initiator and with TPA as promoter.
Coproduction and Ecological Significance of Naphthoquinones in Carnivorous Sundews (Drosera)
Authors: Egan Paul A. , van der Kooy Frank 
Published: June 2012

AbstractWhile the 1,4‐naphthoquinone derivatives 7‐methyljuglone (1) and plumbagin (2) possess a diverse and well documented array of biological activities, relatively little remains known about the functional significance of these compounds in planta and, in particular, their possible relation to carnivorous syndromes. In addition, the chemotaxonomic distribution of naphthoquinones (NQs) amongst species of Drosera L. is of phytopharmaceutical interest. Following the quantitative assessment of interspecific variation of 1 and 2 in 13 species and cultivars of Drosera, our findings demonstrate that these NQs are ubiquitously coproduced in, generally, species‐specific ratios, and that 1 appears negatively associated with the occurrence of pigmentation in sundews. The prospective antifeedant function of 1 was evaluated in relation to allocation in various organs and ontogenetic phases of D. capensis L., revealing that significantly higher levels were accumulated in young and reproductive organs, most likely for defensive purposes. Investigation into the relationship between the biosynthesis of NQs and carnivory showed that production of 1 is optimally induced and localized in leaves in response to capture of insect prey. As a whole, these findings reveal the clear importance of this secondary metabolite in ecological interactions as well as holding implication for future bioactivity studies on the genus.
Melanogenesis‐Inhibitory Saccharide Fatty Acid Esters and Other Constituents of the Fruits of Morinda citrifolia (Noni)
Authors: Akihisa Toshihiro , Tochizawa Shun , Takahashi Nami , Yamamoto Ayako , Zhang Jie , Kikuchi Takashi , Fukatsu Makoto , Tokuda Harukuni , Suzuki Nobutaka 
Published: June 2012

AbstractFive new saccharide fatty acid esters, named nonioside P (3), nonioside Q (4), nonioside R (8), nonioside S (10), and nonioside T (14), and one new succinic acid ester, butyl 2‐hydroxysuccinate (=4‐butoxy‐3‐hydroxy‐4‐oxobutanoic acid) (31), were isolated, along with 26 known compounds, including eight saccharide fatty acid esters, 1, 2, 5, 6, 7, 9, 12, and 13, three hemiterpene glycosides, 15, 17, and 18, six iridoid glycosides, 21–25, and 27, and nine other compounds, 20, 28, 29, and 32–37, from a MeOH extract of the fruit of Morinda citrifolia (noni). Upon evaluation of these and five other glycosidic compounds, 11, 16, 19, 26, and 30, from M. citrifolia fruit extract for their inhibitory activities against melanogenesis in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), most of the saccharide fatty acid esters, hemiterpene glycosides, and iridoid glycosides showed inhibitory effects with no or almost no toxicity to the cells. These compounds were further evaluated with respect to their cytotoxic activities against two human cancer cell lines (HL‐60 and AZ521) and their inhibitory effects on EpsteinBarr virus early antigen (EBV‐EA) activation induced with 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) in Raji cells.
Rational Co‐Immobilization of Bi‐Enzyme Cascades on Porous Supports and their Applications in Bio‐Redox Reactions with In Situ Recycling of Soluble Cofactors
Authors: Rocha‐Martín Javier , Rivas Blanca de las , Muñoz Rosario , Guisán José M , López‐Gallego Fernando 
Published: June 2012

AbstractIn bio‐redox cascade reactions that are immobilized on porous supports, mass‐transfer limitations may impede the effective concentration of the cofactor around the corresponding dehydrogenases. This main drawback has been addressed by the co‐immobilization of both the main and recycling dehydrogenases. Herein, we report tailor‐made co‐immobilization procedures to assemble three different bio‐redox orthogonal cascades in vitro (two selective reductions and one selective oxidation) with in situ cofactor‐regeneration. However, the co‐immobilization itself does not guarantee the success of the biotransformation because the same co‐immobilization chemistry may not be suitable for the two enzymes that are involved in the bio‐redox cascade. Therefore, our co‐immobilization system was optimized for each bi‐enzymatic cascade. In all cases, the optimized co‐immobilization procedure was more efficient in the biocatalytic cascade than if the two dehydrogenases were immobilized on two different carriers. In one specific case (one thermophilic cascade), the co‐immobilization of an optimal ratio of main/recycling dehydrogenases (1:5) on the same carrier resulted in a biocatalyst that was able to recycle NADH up to 9000 times per equivalent of substrate in 1 hour at 55 °C. Moreover, uniform distributions of both dehydrogenases across the porous surface also enhanced the recycling efficiency of the cofactor 1.5‐fold versus cascades in which the enzymes were not uniformly distributed across the same porous surface, presumably because of vicinal cooperation effects. Hence, this system for the co‐immobilization of bi‐enzymatic systems may be extended to other biocatalytic cascades, thereby opening a window for the optimization of other multi‐enzyme biotransformations in which cofactor‐recycling is necessary.
Thermodynamic Analysis of Nonoxidative Dehydroaromatization of Methane
Authors: Moghimpour Bijani P. , Sohrabi M. , Sahebdelfar S. 
Published: June 2012

AbstractThe thermodynamics of methane dehydroaromatization in the absence and presence of coke‐removing agents was studied using the Gibbs free energy minimization approach. Numerical results indicated that higher temperatures and lower pressures increase methane conversion as well as formation of olefins and aromatics but suppress that of paraffins. Higher H2/CH4 ratios enhance the selectivity of light hydrocarbons but reduce that of naphthalene. Benzene selectivity has a maximum at an H2/CH4 molar ratio of 0.26. Methane conversion exhibits a minimum at an H2O/CH4 molar ratio of 0.07. As the H2O/CH4 ratio increases, formations of heavier hydrocarbons decrease at the expense of CO, CO2, and hydrogen. These results may provide guidelines to improve the process performance.
Two‐Component Fibers/Gels and Vesicles Formed from Hetero‐Double‐Helices of Pseudoenantiomeric Ethynylhelicene Oligomers with Branched Side Chains
Authors: Saito Nozomi , Shigeno Masanori , Yamaguchi Masahiko 
Published: June 2012

AbstractA methodology for the formation of fibers/gels and vesicles by molecular assembly and for controlling their properties is presented. Two‐component systems of pentamer (P)‐5 and tetramer (M)‐4 pseudoenantiomeric ethynylhelicenes with decyloxycarbonyl (D) and 4‐methyl‐2‐(2‐methylpropyl)‐1‐pentyloxycarbonyl (bD) side‐chains have been examined. Distinct aggregates were formed by changing the solvent for the three combinations of (P)‐bD‐5/(M)‐bD‐4, (P)‐D‐5/(M)‐bD‐4, and (P)‐D‐5/(M)‐D‐4. In toluene, (P)‐bD‐5/(M)‐bD‐4, (P)‐D‐5/(M)‐bD‐4, and (P)‐D‐5/(M)‐D‐4 all formed gels and fibrous assemblies were observed by AFM. The minimum gel‐forming concentration (MGC) decreased in the order (P)‐bD‐5/(M)‐bD‐4>(P)‐D‐5/(M)‐bD‐4>(P)‐D‐5/(M)‐D‐4. In diethyl ether, vesicular formation was observed by dynamic light scattering (DLS), AFM, and TEM, and the size of the vesicles decreased in the order (P)‐bD‐5/(M)‐bD‐4>(P)‐D‐5/(M)‐bD‐4>(P)‐D‐5/(M)‐D‐4. Both fiber/gel and vesicle formation were accompanied by enhanced CDs and redshifted UV/Vis absorption bands with a change in color to deep yellow. These are novel two‐component oligomeric systems that form assemblies of fibers/gels or vesicles depending on the solvent, and the structures and properties of the assemblies can be fine‐tuned by changing the combination of oligomers. In m‐difluorobenzene, a homogeneous solution was obtained with (P)‐D‐5/(M)‐bD‐4, which again exhibits enhanced CDs and redshifted UV/Vis absorptions. Vapor pressure osmometry analysis showed the formation of a bimolecular heteroaggregate. The study has indicated that pseudoenantiomeric oligomers form hetero‐double‐helices that hierarchically assemble to form fibers/gels and vesicles.
Fabrication Based on the Kirkendall Effect of Co3O4 Porous Nanocages with Extraordinarily High Capacity for Lithium Storage
Authors: Hu Lin , Yan Nan , Chen Qianwang , Zhang Ping , Zhong Hao , Zheng Xinrui , Li Yan , Hu Xianyi 
Published: June 2012

AbstractHerein we report a novel facile strategy for the fabrication of Co3O4 porous nanocages based on the Kirkendall effect, which involves the thermal decomposition of Prussian blue analogue (PBA) Co3[Co(CN)6]2 truncated nanocubes at 400 °C. Owing to the volume loss and release of internally generated CO2 and NxOy in the process of interdiffusion, Co3O4 nanocages with porous shells and containing nanoparticles were finally obtained. When evaluated as electrode materials for lithium‐ion batteries, the as‐prepared Co3O4 porous nanocages displayed superior battery performance. Most importantly, capacities of up to 1465 mA h g−1 are attained after 50 cycles at a current density of 300 mA g−1. Moreover, this simple synthetic strategy is potentially competitive for scaling‐up industrial production.
Three Types of Induced Tryptophan Optical Activity Compared in Model Dipeptides: Theory and Experiment
Authors: Hudecová Jana , Horníček Jan , Buděšínský Miloš , Šebestík Jaroslav , Šafařík Martin , Zhang Ge , Keiderling Timothy A. , Bouř Petr 
Published: June 2012

AbstractThe tryptophan (Trp) aromatic residue in chiral matrices often exhibits a large optical activity and thus provides valuable structural information. However, it can also obscure spectral contributions from other peptide parts. To better understand the induced chirality, electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) spectra of Trp‐containing cyclic dipeptides c‐(Trp‐X) (where X=Gly, Ala, Trp, Leu, nLeu, and Pro) are analyzed on the basis of experimental spectra and density functional theory (DFT) computations. The results provide valuable insight into the molecular conformational and spectroscopic behavior of Trp. Whereas the ECD is dominated by Trp π–π* transitions, VCD is dominated by the amide modes, well separated from minor Trp contributions. The ROA signal is the most complex. However, an ROA marker band at 1554 cm−1 indicates the local χ2 angle value in this residue, in accordance with previous theoretical predictions. The spectra and computations also indicate that the peptide ring is nonplanar, with a shallow potential so that the nonplanarity is primarily induced by the side chains. Dispersion‐corrected DFT calculations provide better results than plain DFT, but comparison with experiment suggests that they overestimate the stability of the folded conformers. Molecular dynamics simulations and NMR results also confirm a limited accuracy of the dispersion‐DFT model in nonaqueous solvents. Combination of chiral spectroscopies with theoretical analysis thus significantly enhances the information that can be obtained from the induced chirality of the Trp aromatic residue.
Multichromophoric Calix[4]arenes: Effect of Interchromophore Distances on Linear and Nonlinear Optical Properties
Authors: Andreu Raquel , Franco Santiago , Garín Javier , Romero Judith , Villacampa Belén , Blesa María Jesús , Orduna Jesús 
Published: June 2012

AbstractMultichromophoric calix[4]arenes with two or four disperse red one (DR1) moieties linked to the lower rim have been synthesized. The second‐order nonlinear optical activity was measured by using the electric‐field‐induced second‐harmonic generation technique and there was a nearly linear increase of the μβ value with the number of chromophores in the molecule without affecting the charge‐transfer absorption wavelength. The effect that the number of DR1 units plays on the hyperpolarizability, the dipole moment, and the absorption maxima has been also studied by using quantum chemical calculations. It was found that it was necessary to synthesize multichromophores with distant chromophores to obtain large nonlinear optical responses.
Microwave‐Assisted Modular Fabrication of Nanoscale Luminescent Metal‐Organic Framework for Molecular Sensing
Authors: Yang Weiting , Feng Jing , Song Shuyan , Zhang Hongjie 
Published: June 2012

AbstractMiniaturizing the size of metal‐organic framework (MOF) crystals to the nanometer scale is challenging, but it provides more advanced applications without changing the characteristic features itself. It is especially useful to investigate the correlation between the porous properties and the interfacial structures of nanocrystals. Using amino acids as capping agents, nanoscale Tb‐MOF‐76 is fabricated rapidly by means of microwave‐assisted methods. Both the modular effects of the amimo acids and the acid–base environment of the reaction medium have an important impact on the morphologies and dimensions of Tb‐MOF‐76. The structures of the samples are confirmed by powder X‐ray diffraction, and the morphologies are characterized by SEM. Photoluminescence studies reveal that these Tb‐MOF‐76 materials exhibit a green emission corresponding to the transition 5D4→7FJ of Tb3+ ions under UV‐light excitation, which is sensitive to small organic molecules in solution.
Cooperative and Diminutive Interplay Between Lithium and Dihydrogen Bonding in F3YLi…︁NCH…︁HMH and F3YLi…︁HMH…︁HCN Triads (Y=C, Si; M=Be, Mg)
Authors: Solimannejad Mohammad 
Published: June 2012

AbstractThe F3YLi…NCH…HMH and F3YLi…HMH…HCN triads (Y=C, Si; M=Be, and Mg) are connected by lithium and dihydrogen bonds. To understand the properties of the systems better, the corresponding dyads are also studied. Molecular geometries, binding energies, infrared spectra and NMR properties of monomers, dyads, and triads are investigated at the MP2/6‐311++G** computational level. Particular attention is paid to parameters, such as cooperative energies, and many‐body interaction energies. Triads with the HMH molecule located at the end of the chain, show energetic cooperativity ranging between −3.66 to −7.59 kJ mol‐1. When the HMH molecule is located in the middle, the obtained cluster is diminutive with an energetic effect between 3.49 to 5.17 kJ mol‐1. The electronic properties of the complexes are analyzed using parameters derived from the atoms in molecules (AIM) methodology.
Metal‐Free Photocatalytic Graphitic Carbon Nitride on p‐Type Chalcopyrite as a Composite Photocathode for Light‐Induced Hydrogen Evolution
Authors: Yang Florent , Lublow Michael , Orthmann Steven , Merschjann Christoph , Tyborski Tobias , Rusu Marin , Kubala Sven , Thomas Arne , Arrigo Rosa , Hävecker Michael , Schedel‐Niedrig Thomas 
Published: June 2012

AbstractRecently, it has been shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible‐light irradiation in the presence of a sacrificial donor. We present herein the preparation and characterization of graphitic carbon nitride (g‐C3N4) films on p‐type semiconducting CuGaSe2 chalcopyrite thin‐film substrates by thermal condensation of a dicyandiamide precursor under inert‐gas conditions. Structural and surface morphological studies of the carbon nitride films suggest a high porosity of g‐C3N4 thin films consisting of a network of nanocrystallites. Photoelectrochemical investigations show light‐induced hydrogen evolution upon cathodic polarization for a wide range of proton concentrations in the aqueous electrolyte. Additionally, synchrotron radiation‐based photoelectron spectroscopy has been applied to study the surface/near‐surface chemical composition of the utilized g‐C3N4 film photocathodes. For the first time, it has been shown that g‐C3N4 films coated on p‐type CuGaSe2 thin films can be successfully applied as new photoelectrochemical composite photocathodes for light‐induced hydrogen evolution.
Temperature‐/Pressure‐Dependent Selective Separation of CO2 or Benzene in a Chiral Metal–Organic Framework Material
Authors: Tan Yan‐Xi , He Yan‐Ping , Zhang Jian 
Published: June 2012

AbstractPresented here is a chiral microporous metal–organic framework material with a three‐fold interpenetrating diamond‐type structural topology and interesting properties for selective separation. The material has a high storage capacity for CO2 gas (4.23 mmol g−1 at 273 K and 1 bar) and shows fantastic temperature‐dependent selectivity for CO2 over N2. Moreover, this multifunctional material, which has a rich π system, can selectively adsorb benzene over cyclohexane at low pressure (0.05 bar) at 298 K.
Nth best relay selection with network coding in two‐way relay systems
Authors: Han Bin , Wang Wenbo , Zhao Zhongyuan , Peng Mugen 
Published: June 2012

SUMMARYIn this paper, we propose an Nth best relay selection (Nth‐RS) scheme for analog network coding in two‐way relay systems. In traditional two‐way single‐relay selection schemes, only the best one is selected to forward network‐coded signals. However, in practical applications, the best relay may be unavailable because of the scheduling or overload constraints. In this case, we investigate a more general scheme, where the Nth best but available relay is selected. To evaluate the transmission of reliability, the expression of outage probability in exponential–integral form and its asymptotic expression in closed form are presented. Moreover, the upper bound and lower bound of outage probability are also derived. The analysis reveals that the diversity order of Nth‐RS equals to (M − N + 1), where M is the number of relay nodes, and the results are verified by simulations. In order to improve system performance, transmit power between sources and relay is optimally allocated to minimize the upper bound of outage probability under total power constraint. Simulation results show that Nth‐RS scheme with proposed power allocation can achieve substantial improvement over equal power allocation scheme. Copyright © 2012 John Wiley & Sons, Ltd.
Flying with the birds? Recent large‐area dispersal of four Australian Limnadopsis species (Crustacea: Branchiopoda: Spinicaudata)
Authors: Schwentner Martin , Timms Brian V. , Richter Stefan 
Published: June 2012

AbstractTemporary water bodies are important freshwater habitats in the arid zone of Australia. They harbor a distinct fauna and provide important feeding and breeding grounds for water birds. This paper assesses, on the basis of haplotype networks, analyses of molecular variation and relaxed molecular clock divergence time estimates, the phylogeographic history, and population structure of four common temporary water species of the Australian endemic clam shrimp taxon Limnadopsis in eastern and central Australia (an area of >1,350,000 km2). Mitochondrial cytochrome c oxidase subunit I sequences of 413 individuals and a subset of 63 nuclear internal transcribed spacer 2 sequences were analyzed. Genetic differentiation was observed between populations inhabiting southeastern and central Australia and those inhabiting the northern Lake Eyre Basin and Western Australia. However, over large parts of the study area and across river drainage systems in southeastern and central Australia (the Murray–Darling Basin, Bulloo River, and southern Lake Eyre Basin), no evidence of population subdivision was observed in any of the four Limnadopsis species. This indicates recent gene flow across an area of ∼800,000 km2. This finding contrasts with patterns observed in other Australian arid zone taxa, particularly freshwater species, whose populations are often structured according to drainage systems. The lack of genetic differentiation within the area in question may be linked to the huge number of highly nomadic water birds that potentially disperse the resting eggs of Limnadopsis among temporary water bodies. Genetically undifferentiated populations on a large geographic scale contrast starkly with findings for many other large branchiopods in other parts of the world, where pronounced genetic structure is often observed even in populations inhabiting pools separated by a few kilometers. Due to its divergent genetic lineages (up to 5.6% uncorrected p‐distance) and the relaxed molecular clock divergence time estimates obtained, Limnadopsis parvispinus is assumed to have inhabited the Murray–Darling Basin continuously since the mid‐Pliocene (∼4 million years ago). This means that suitable temporary water bodies would have existed in this area throughout the wet–dry cycles of the Pleistocene.