bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimycobacterial Butanolides from the Root of Lindera akoensis
Authors: Chang Su‐Yen , Cheng Ming‐Jen , Peng Chien‐Fang , Chang Hsun‐Shuo , Chen Ih‐Sheng 
Published: December 2008

AbstractThree racemic butanolides, majorenolide (1), majorynolide (2), and majoranolide (3), with 18 known compounds, including ten butanolides, i.e., litsenolide A2 (4), litsenolide B2 (5), litsenolide C1 (6), litsenolide C2 (7), hamabiwalactone A (8), hamabiwalactone B (9), litseakolide A (10), litseakolide B (11), isoobtusilactone (12), and obtusilactone (13); one lignan, i.e., (±)‐syringaresinol (14), two flavans, i.e., (+)‐catechin (15), and (−)‐epicatechin (16), one coumarin, i.e., scopoletin (17), and four steroids, i.e., a mixture of β‐sitosterol (18) and stigmasterol (19), and a mixture of β‐sitosteryl‐3‐O‐β‐D‐glucoside (20) and stigmasteryl‐3‐O‐β‐D‐glucoside (21) were isolated from the root of Lindera akoensis. The structures of the isolates were elucidated by in‐depth spectroscopic analysis. Compounds 1–3 were previously assigned a δ‐lactone structure, which was then revised to a γ‐lactone structure, based on 1D‐NMR data. The cigar‐HMBC technique was used to confirm the accuracy of the γ‐lactone structure, and the zero [α]$\rm{ _{\rm{D}}^{20} }$ value of compounds 1–3 suggested that they were considerably racemized. Nine butanolides 1–3, 4–8, and 10 showed antimycobacterial activities against M. tuberculosis H37Rv, with MIC values of 15–50 μg/ml.
Effects of Compounds Isolated from the Fruits of Rumex japonicus on the Protein Glycation
Authors: Jang Dae Sik , Kim Jong Min , Kim Junghyun , Yoo Jeong Lim , Kim Young Sook , Kim Jin Sook 
Published: December 2008

AbstractAn anthraquinone, emodin (1), and five flavonoids, kaempferol‐3‐O‐β‐D‐glucoside (2), quercetin (3), quercitrin (4), isoquercitrin (5), and (+)‐catechin (6), were isolated from an AcOEt‐soluble extract of the fruits of Rumex japonicus. Their structures were determined by spectroscopic data interpretation. All the isolates were evaluated for their potential to inhibit AGEs (advanced glycation end products) formation and AGEs cross‐linking, and to break already formed AGEs cross‐links.
trans–cis Photoisomerization of Azobenzene‐Conjugated Dithiolato‐Bipyridine Platinum(II) Complexes: Extension of Photoresponse to Longer Wavelengths and Photocontrollable Tristability
Authors: Sakamoto Ryota , Kume Shoko , Sugimoto Manabu , Nishihara Hiroshi 
Published: December 2008

AbstractAzobenzene derivatives modified with dithiolato‐bipyridine platinum(II) complexes were synthesized, revealing their highly extended photoresponses to the long wavelength region as well as unique photocontrollable tristability. The absorptions of trans‐1 and trans‐2 with one azobenzene group on the dithiolene and bipyridine ligands, respectively, cover the range from 300 to 700 nm. These absorptions are ascribed, by means of time‐dependent (TD)DFT calculations, to transitions from dithiolene(π) to bipyridine(π*), namely, interligand charge transfer (CT), π–π*, and n–π* transitions of the azobenzene unit, and π–π* transitions of the bipyridine ligand. In addition, only trans‐1 shows distinctive electronic bands, assignable to transitions from the dithiolene(π) to azobenzene(π*), defined as intraligand CT. Complex 1 shows photoisomerization behavior opposite to that of azobenzene: trans‐to‐cis and cis‐to‐trans conversions proceed with 405 and 312 nm irradiation, which correspond to excitation with the intraligand CT, and π–π* bands of the azobenzene and bipyridine units, respectively. In contrast, complex 2 shows photoisomerization similar to that of azobenzene: trans‐to‐cis and cis‐to‐trans transformations occur with 365 and 405 nm irradiation, respectively. Irradiation at 578 nm, corresponding to excitation of the interligand CT transitions, results in cis‐to‐trans conversion of both 1 and 2, which is the longest wavelength ever reported to effect the photoisomerization of the azobenzene group. The absorption and photochromism of 4, which has azobenzene groups on both the dithiolato and bipyridine ligands, have characteristics quite similar to those of 1 and 2, which furnishes 4 with photocontrollable tristability in a single molecule using light at 365, 405, and 578 nm. We also clarified that 1 and 2 have high photoisomerization efficiencies, and good thermal stability of the cis forms. Complexes 3 and 5 have almost the identical photoresponse to those of their positional isomers, complexes 2 and 4.
Spin Crossover in a Family of Iron(II) Complexes with Hexadentate ligands: Ligand Strain as a Factor Determining the Transition Temperature
Authors: Matouzenko Galina S. , Borshch Serguei A. , Jeanneau Erwann , Bushuev Mark B. 
Published: December 2008

AbstractThis paper reports the synthesis of a family of mononuclear complexes [Fe(L)]X2 (X=BF4, PF6, ClO4) with hexadentate ligands L=Hpy‐DAPP ({bis[N‐(2‐pyridylmethyl)‐3‐aminopropyl](2‐pyridylmethyl)amine}), Hpy‐EPPA ({[N‐(2‐pyridylmethyl)‐3‐aminopropyl][N‐(2‐pyridylmethyl)‐2‐aminoethyl](2‐pyridylmethyl)amine}) and Hpy‐DEPA ({bis[N‐(2‐pyridylmethyl)‐2‐aminoethyl](2‐pyridylmethyl)amine}). The systematic change of the length of amino‐aliphatic chains in these ligands results in chelate rings of different size: two six‐membered rings for Hpy‐DAPP, one five‐ and one six‐membered rings for Hpy‐EPPA, and two five‐membered rings for Hpy‐DEPA. The X‐ray analysis of three low‐spin complexes [Fe(L)](BF4)2 revealed similarities in their molecular and crystal structures. The magnetic measurements have shown that all synthesized complexes display spin‐crossover behavior. The spin‐transition temperature increases upon the change from six‐membered to five‐membered chelate rings, clearly demonstrating the role of the ligand strain. This effect does not depend on the nature of the counter ion. We discuss the structural features accountable for the strain effect on the spin‐transition temperature.
Formation of Tantalum Carbide and Nitride Phases in Atomic Layer Deposition Using Hydrogen Plasma and tert‐Butylimido‐tris(diethylamido)‐tantalum (TBTDET), and its Effect on Material Properties
Authors: Song Moon‐Kyun , Rhee Shi‐Woo 
Published: December 2008

AbstractTaCN films are deposited with plasma‐enhanced atomic layer deposition (PEALD) using tert‐butylimido‐tris(diethylamido)‐tantalum and hydrogen. It is confirmed that the film is a homogeneous mixture of TaC, TaN, Ta3N5, and Ta2O5 with the oxide phase formed from the post‐deposition uptake of oxygen from the air. It is shown that the electrical properties of TaCN film are affected by the phase composition in the film. The effects of process parameters, such as deposition temperature, plasma power, and cycle time, on the film composition and electronic properties are evaluated. With the increase of the TaC and TaN phases over the Ta3N5 phase, the resistivity of the film is decreased. As the deposition temperature, plasma power, and plasma cycle time are increased, the carbide and TaN phases in the film are increased and the film resistivity is decreased. The uptake of oxygen after deposition is up to 10 at.‐%, and the resistivity of TaCN film deposited using PEALD is as low as 350 µΩ · cm.
Study of Atmospheric MOCVD of TiO2 Thin Films by Means of Computational Fluid Dynamics Simulations
Authors: Baguer Neyda , Neyts Erik , Van Gils Sake , Bogaerts Annemie 
Published: December 2008

AbstractThis paper presents the computational study of the metal‐organic (MO) CVD of titanium dioxide (TiO2) films grown using titanium tetraisopropoxide (TTIP) as a precursor and nitrogen as a carrier gas. The TiO2 films are deposited under atmospheric pressure. The effects of the precursor concentration, the substrate temperature, and the hydrolysis reaction on the deposition process are investigated. It is found that hydrolysis of the TTIP decreases the onset temperature of the gas‐phase thermal decomposition, and that the deposition rate increases with the precursor concentration and with the decrease of substrate temperature. Concerning the mechanism responsible for the film growth, the model shows that at the lowest precursor concentration, the direct adsorption of the precursor is dominant, while at higher precursor concentrations, the monomer deposition becomes more important.
Controlling the Size and Density of Silicon Nanostructures by Incorporation of Nitrogen
Authors: Kiebach Ragnar , Yu Zhenrui , Aceves‐Mijares Mariano , Du Jinhui , Bian Dongcai , López‐Estopier Rosa , Carrillo‐Lopez Jesús , Juárez‐Diaz Gabriel , Juarez Javier Martinez 
Published: December 2008

AbstractSi nanostructures are prepared by thermal annealing of silicon rich oxide (SRO) which is deposited using low pressure (LP) CVD. X‐ray diffraction (XRD), Raman spectroscopy, infrared (IR) spectroscopy, and transmission electron microscopy (TEM) are used to characterize the structure of the Si nanocrystals and nanoislands. The density, crystallinity, and size of the Si nanoislands and Si nanocrystals can be controlled by the amount of nitrogen hosted in the SRO. The Si and SiO2 phase separation of the SRO during the annealing process is hindered by the incorporation of nitrogen.
Magnetic Field Effects on the Formation and Properties of Nickel Nanostructures
Authors: Sun Lixia , Chen Qianwang 
Published: December 2008

AbstractA facile solvothermal hydrazine reduction route was designed for the synthesis of shape‐controlled one‐dimensional (1D) nickel wires in the presence of magnetic fields. The reaction conditions involved were studied systematically to select the optimal reaction parameters to reveal the effects of weak magnetic fields on the formation and properties of nickel nanostructures. The magnetic‐field‐dependent formation of 1D nickel wires indicated that the reduction of nickel ions with concentration less than 0.21 M preferentially occurs along the magnetic line of force, leading to the formation of uniform 1D wires, whereas higher concentrations could lead to quick reaction in the whole system and formation of isolated particles coexisting with wires composed of microspheres formed along the magnetic line of force. The improved magnetic properties of the sample formed in a magnetic field relative to those of samples formed without an applied field may be due to variation of the magnetic domain structure in the 1D nickel wires. Moreover, it was found that microwave absorption of a 1D nickel wire/poly(methyl methacrylate) (PMMA) composite at 8.5–12.5 GHz was evidently enhanced relative to that of a nickel microsphere/PMMA composite, which indicates that the anisotropic wires are not simply an assembly of particles, but that the magnetic domain structures in wires has been changed by the applied field.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
New Terpenoid Constituents of the Southwestern Caribbean Sea Whip Pseudopterogorgia elisabethae (Bayer), Including a Unique Pentanorditerpene
Authors: Shi Yan‐Ping , Wei Xiaomei , Rodríguez Ileana I. , Rodríguez Abimael D. , Mayer Alejandro M. S. 
Published: December 2008

AbstractSeven structurally diverse terpenoids, including four diterpenes, a norditerpene, a bisnorditerpene, and a biogenetically related pentanorditerpene, have been isolated from the hexane extract of the Caribbean gorgonian octocoral Pseudopterogorgia elisabethae, collected near the island of San Andrés, Colombia. The structures of all the new compounds were determined by detailed spectroscopic analysis and chemical derivatization. Many of the purified isolates were evaluated in vitro as potential agents to treat neuroinflammation and also as growth inhibitors against the pathogenic microbe Mycobacterium tuberculosis H37Rv.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Photocyclodimerization of 5‐Methyl‐2H‐pyran‐3(6H)‐one
Authors: Groesch Ljubov , Kopf Jürgen , Margaretha Paul 
Published: December 2008

AbstractThe structures of the main products resulting from photocyclodimerization of the title compound 2 and of other 3‐methyl‐substituted ‘oxacyclohex‐2‐en‐1‐ones’ (=dihydropyranones) were determined by X‐ray crystallography. In connection, the 13C‐NMR chemical shifts of the cyclobutane C‐atoms of these dimers allow a clear differentiation between head‐to‐head and head‐to‐tail regioisomers, all structurally related to those of isophorone (1).
Iridoids from the Bark of Alstonia scholaris
Authors: Feng Tao , Cai Xiang‐Hai , Du Zhi‐Zhi , Luo Xiao‐Dong 
Published: December 2008

AbstractFour new 11‐noriridoids named scholareins A–D (1–4), along with three known derivatives, isoboonein (5), alyxialactone (6), and loganin (7), were isolated from EtOH extracts of the bark of Alstonia scholaris by chromatographic methods. Their structures were identified by extensive mass‐spectrometric and spectroscopic (especially 2D‐NMR) experiments.
One‐Pot Diastereoselective Synthesis of Densely Functionalized 2H‐Indeno[2,1‐b]furans. Single‐Crystal X‐Ray Structure of Dimethyl 8,8a‐Dihydro‐8‐oxo‐8a‐(2,2,2‐trichloroethoxy)‐2H‐indeno[2,1‐b]furan‐2,3‐di­carboxylate
Authors: Ramazani Ali , Noshiranzadeh Nader , Ghamkhari Alieh , Ślepokura Katarzyna , Lis Tadeusz 
Published: December 2008

AbstractHighly reactive 1 : 1 intermediates were produced in the reaction of Ph3P and dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates). Protonation of these intermediates by alcohols (2,2,2‐trichloroethanol, propargyl alcohol (=prop‐2‐yn‐1‐ol), MeOH, benzyl alcohol, and allyl alcohol (=prop‐2‐en‐1‐ol) led to vinyltriphenylphosphonium salts 4, which underwent a Michael addition reaction with the conjugate base to produce the corresponding stabilized phosphonium ylides 5 (Scheme). Wittig reaction of the stabilized phosphonium ylides with ninhydrin (6) led to the corresponding densely functionalized 2H‐indeno[2,1‐b]furans 10 in fairly good yields (Table 1). The structures of the final products were confirmed by IR, 1H‐ and 13C‐NMR spectroscopy, and mass spectrometry. The configuration of dimethyl 8,8a‐dihydro‐8‐oxo‐8a‐(2,2,2‐trichloroethoxy)‐2H‐indeno[2,1‐b]furan‐2,3‐dicarboxylate (10a) was established by a single‐crystal X‐ray structure determination, establishing that the one‐pot multicomponent condensation reaction was completely diastereoselective.
Withanolides from Physalis alkekengi var. francheti
Authors: Li Yi‐Zheng , Pan Ying‐Ming , Huang Xiao‐Yan , Wang Heng‐Shan 
Published: December 2008

AbstractTwo new withanolides, namely (20S,22R)‐15α‐acetoxy‐5α‐chloro‐6β,14β‐dihydroxy‐1‐oxowitha‐2,24‐dienolide (1) and (22R)‐5β,6β : 14α,17 : 14β,26‐triepoxy‐2α‐ethoxy‐13,20,22‐trihydroxy‐1,15‐dioxo‐16α,24‐cyclo‐13,14‐secoergosta‐18,27‐dioic acid 18→20,27→22‐dilactone (2), along with six known compounds, physagulin B (3), withangulatin A (4), physalin I (5), withaminimin (6), physagulin J (7), and ergosta‐5,25‐diene‐3β,24ξ‐diol (8), were isolated from the whole plant of Physalis alkekengi var. francheti. Their structures were elucidated on the basis of spectroscopic analyses.
Reductions of Benzene Derivatives Whose Benzylic Positions Bear Oxygen Atoms under Mild Conditions
Authors: Menzek Abdullah , Karakaya Melek Gökmen , Kaya Afşin Ahmet 
Published: December 2008

AbstractReductions of compounds whose benzylic positions bear O‐atoms, such as benzyl alcohol, dibenzyl ether, styrene oxide, benzaldehyde, acetophenone, and benzophenone, to the corresponding non‐conjugated dienes were performed by using t‐BuOH, Li, and gaseous NH3 in THF at room temperature. In these reductions, it was observed that the functional groups at benzylic positions were reduced first.
Liquid‐Crystalline Thiol‐ and Disulfide‐Based Dendrimers for the Functionalization of Gold Nanoparticles. Preliminary Communication
Authors: Frein Stéphane , Boudon Julien , Vonlanthen Mireille , Scharf Toralf , Barberá Joaquín , Süss‐Fink Georg , Bürgi Thomas , Deschenaux Robert 
Published: December 2008

AbstractLiquid‐crystalline dendrons carrying either a thiol or disulfide function which display nematic, smectic A, columnar, or chiral nematic phases have been synthesized. Their mesomorphic properties are in agreement with the nature of the mesogenic units and structure of the dendrons. The first‐generation poly(aryl ester) dendron containing two cyanobiphenyl mesogenic units was used to functionalize gold nanoparticles. For full coverage, a smectic‐like supramolecular organization on the nanometer scale is observed, when the gold nanoparticles are spread onto carbon‐coated copper grids. This result indicates that the dendritic ligands reported here act as self‐organization promoters.
Late Quaternary landscape development along the Rancho Marino coastal range front (south‐central Pacific Coast Ranges, California, USA)
Authors: Stokes Martin , García Antonio F. 
Published: December 2008

AbstractLate Quaternary landscape development along the Rancho Marino coastal range front in the central‐southern Pacific Coast Ranges of California has been documented using field mapping, surveying, sedimentary facies analysis and a luminescence age determination. Late Quaternary sediments along the base of the range front form a single composite marine terrace buried by alluvial fans. Marine terrace sediments overlie two palaeoshore platforms at 5 m and 0 m altitude. Correlation with the nearby Cayucos and San Simeon sites links platform and marine terrace development to the 125 ka and 105 ka sea‐level highstands. Uplift rate estimates based on the 125 ka shoreline angle are 0.01–0.09 m ka−1 (mean 0.04 m ka−1), and suggest an increase in regional uplift along the coast towards the NW where the San Simeon fault zone intersects the coastline. Furthermore, such low rates suggest that pre‐125 ka uplift was responsible for most of the relief generation at Rancho Marino. The coastal range front landscape development is, thus, primarily controlled by post 125 ka climatic and sea‐level changes. Post 125 ka sea‐level lowering expanded the range front piedmont area to a width of 7.5 km by the 18 ka Last Glacial Maximum lowstand. This sea‐level lowering created space for alluvial fan building along the range front. A 45 ± 3 ka optically stimulated luminescence (OSL) age provides a basal age for alluvial fan building or marks the time by which distal alluvial fan sedimentation has reached 300 m from the range front slope. Fan sedimentation is related to climatic change, with increased sediment supply to the range front occurring during (1) glacial period cold stage maxima and/or (2) the Late Pleistocene–Holocene transition, when respective increases in precipitation and/or storminess resulted in hillslope erosion. Sea‐level rise after the 18 ka lowstand resulted in range front erosion, with elevated localised erosion linked to the higher relief and steeper slopes in the SE. This study demonstrates that late Quaternary coastal range front landscape development is driven by interplay of tectonics, climatic and sea‐level change. In areas of low tectonic activity, climatic and sea‐level changes dominate coastal landscape development. When the sea‐level controlled shoreline is in close proximity to the coastal range front, localised patterns of sedimentation and erosion are passively influenced by the pre‐125 ka topography. Copyright © 2008 John Wiley & Sons, Ltd.
Assessment of the Extent of Starch Dissolution in Dimethyl Sulfoxide by 1H NMR Spectroscopy
Authors: Schmitz Sarah , Dona Anthony C. , Castignolles Patrice , Gilbert Robert G. , Gaborieau Marianne 
Published: December 2008

AbstractComplete dissolution is needed for the separation, characterization, or homogeneous labeling of whole starch molecules. A method is presented to quantify the extent of starch dissolution in DMSO for the first time; it is validated on a commercial rice starch. It is used directly on starch dispersions containing possible undissolved or co‐dissolved species. High‐amylose maize starches, known to be digested slowly in vivo, only quantitatively dissolve in the presence of high concentrations of an H‐bond disrupter, LiBr, although they form clear dispersions at low LiBr concentrations. Starch quantitatively dissolves from waxy rice flours; non‐starch components partially co‐dissolve but do not interfere with the dissolution quantification.magnified image
Fatigue and corrosion fatigue behavior of 13Cr and duplex stainless steel and a welded nickel alloy employed in oil and gas production
Authors: Schroeder R. M. , Müller I. L. 
Published: December 2008

AbstractThe materials used in off‐shore oil and gas production, e.g. in risers, are often exposed to cyclic loads from the water movement because of their contact with seawater. These factors acting together can develop a corrosion fatigue (CF) process. A duplex and a 13% chromium (13Cr) wrought stainless steel (SS) and a welded nickel base alloy Inconel 625 were tested at different cyclic load magnitudes in an eccentric fatigue machine type. The specimens were tested in the presence of a corrosive environment at low loading frequencies (0.3 Hz). The medium used was an aqueous solution with 115.000 ppm of chloride, pH adjusted to 4, and CO2bubbling inside the solution during the test. The end of the test was determined in maximum 500.000 cycles (23 days for frequency of 0.3 Hz) if no fracture occurred before. In the 13Cr steel the fissure seems to propagate in a uniform unique path, while in the duplex steel the crack changes the direction when passing from the ferritic to austenitic grains. The propagation speed seems to be different in the ferrite and in the austenitic structures. Among the materials tested the Inconel 625 alloy, even being in the welded condition, showed higher CF strength than the SSs; 13Cr shows better results when compared with the duplex steel, even though the last one would be more corrosion resistant.
Oxygen Barrier Properties of Poly(ethylene terephthalate) Nanocomposite Films
Authors: Frounchi Masoud , Dourbash Alireza 
Published: December 2008

AbstractNanocomposites of poly(ethylene terephthalate) and two different montmorillonite‐based organoclays were prepared by a co‐rotating twin screw extruder. Dispersion of nanoclays in the polymer matrix was examined by TEM and XRD. Nanocomposites with lower content of organoclay showed exfoliated morphology while by increasing the amount of organoclay the intercalated morphology was more prevalent. Both organoclays had a good intercalation with PET and were uniformly dispersed within the polymer. Oxygen permeability of thin films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. Tensile and impact properties of the nanocomposites also were measured.magnified image
Water Storage in Thin Films Maintaining the Total Film Thickness as Probed with in situ Neutron Reflectivity
Authors: Wang Weinan , Metwalli Ezzeldin , Perlich Jan , Troll Kordelia , Papadakis Christine M. , Cubitt Robert , Müller‐Buschbaum Peter 
Published: December 2008

AbstractWe investigate a new type of thin film material which allows for water storage without an increase in film thickness, whereas typically water storage in polymers and polymer films is accompanied with a strong swelling of the film, i.e., a strong increase in the film thickness. So these films will avoid problems related to strains which are caused by swelling. The basic key for the preparation of such thin films is the installation of a glassy network by the use of an asymmetric diblock copolymer polystyrene‐block‐poly(N‐isopropylacrylamide) [P(S‐b‐NIPAM)] with a long PS and short PNIPAM block in combination with a solvent which is more equal in interaction with both the blocks as compared to water. With in situ neutron reflectivity the water storage and removal are probed. The total film thickness increases only by 2.5% by allowing for a total water storage of 17.4%. Thus the material can be used for coatings to reduce humidity in nano‐applications, which might suffer from changes in the water content of the surrounding environment.magnified image