bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards Supramolecular Fixation of NOX Gases: Encapsulated Reagents for Nitrosation
Authors: Kang Yanlong , Zyryanov Grigory V. , Rudkevich Dmitry M. 
Published: January 2005

AbstractThe use of simple calix[4]arenes for chemical conversion of NO2/N2O4 gases is demonstrated in solution and in the solid state. Upon reacting with these gases, calixarenes 1 encapsulate nitrosonium (NO+) cations within their cavities with the formation of stable calixarene–NO+ complexes 2. These complexes act as encapsulated nitrosating reagents; cavity effects control their reactivity and selectivity. Complexes 2 were effectively used for nitrosation of secondary amides 5, including chiral derivatives. Unique size–shape selectivity was observed, allowing for exclusive nitrosation of less crowded N‐Me amides 5 a–e (up to 95 % yields). Bulkier N‐Alk (Alk>Me) substrates 5 did not react due to the hindered approach to the encapsulated NO+ reagents. Robust, silica gel based calixarene material 3 was prepared, which reversibly traps NO2/N2O4 with the formation of NO+‐storing silica gel 4. With material 4, similar size–shape selectivity was observed for nitrosation. The N‐Me–N‐nitroso derivatives 6 d,e were obtained with ∼30 % yields, while bulkier amides were nitrosated with much lower yields (<8 %). Enantiomerically pure encapsulating reagent 2 d was tested for nitrosation of racemic amide 5 t, showing modest but reproducible stereoselectivity and ∼15 % ee. Given high affinity to NO+ species, which can be generated by a number of NOX gases, these supramolecular reagents and materials may be useful for NOX entrapment and separation in the environment and biomedical areas.
Synthesis, Characterization, and Complexation of Tetraarylborates with Aromatic Cations and Their Use in Chemical Sensors
Authors: Alaviuhkola Terhi , Bobacka Johan , Nissinen Maija , Rissanen Kari , Ivaska Ari , Pursiainen Jouni 
Published: January 2005

AbstractFive aromatic borate anions, namely tetrakis(4‐phenoxyphenyl)borate (1), tetrakis(biphenyl)borate (2), tetrakis(2‐naphthyl)borate (3), tetrakis(4‐phenylphenol)borate (4), and tetrakis(4‐phenoxy)borate (5), have been prepared and tested as ion‐recognition sites in chemical sensors for certain aromatic cations and metal ions. To gain further insight into the complexation of the cations, some complexes have been prepared and structurally characterized. The complexation behavior of 1 and 2 towards N‐methylpyridinium (6), 1‐ethyl‐4‐(methoxycarbonyl)pyridinium (7), tropylium (8), imidazolium (9), and 1‐methylimidazolium (10) cations has been studied, and the stability constants of the complexes of 1 with cations 6 and 8 have been measured to compare them with the values for the previously studied complexes of tetraphenylborate. The structures of the borate anions and their complexes have been characterized by NMR and mass spectrometric methods. X‐ray crystal structures have been determined for potassium tetrakis(4‐phenoxyphenyl)borate (K+⋅1), N‐methylpyridinium tetrakis(4‐phenoxyphenyl)borate (6⋅1), 1‐ethyl‐4‐(methoxycarbonyl)pyridinium tetrakis(4‐phenoxyphenyl)borate (7⋅1), tropylium tetrakis(4‐phenoxyphenyl)borate (8⋅1), and imidazolium tetrakis(biphenyl)borate (9⋅2). The results show that borate derivatives are potential candidates for a completely new family of charged carriers for use in cation‐selective electrodes.
Direct Assignment of Enantiofacial Discrimination on Single Heterocyclic Substrates by Self‐induced CD
Authors: Siering Carsten , Grimme Stefan , Waldvogel Siegfried R. 
Published: January 2005

AbstractThe first direct assignment of highly dynamic enantiofacial discrimination acting on a single heterocyclic substrate has been achieved by a combination of experimental and theoretical CD spectroscopy. The interaction of chirally modified hosts based on triphenylene ketals with appropriate prochiral guests can lead to the preferential formation of one diastereomeric host–guest complex. This reversible stereoselective binding transmits the chiral information from remote chiral groups in the host to the strongly absorbing triphenylene chromophore, which gives rise to self‐induced CD. This effect was exploited for the determination of the enantiofacial recognition in various host–guest systems. Inversion of the steric demand either of the chiral substituents at the host or of the prochiral guest leads to almost complete inversion of the resulting CD spectra. For the assignment of the absolute stereochemistry of the complexes, a combined molecular dynamics/quantum‐chemical approach was successfully employed. Despite the size and the highly dynamic character of the supramolecular systems, fundamental properties of the systems and details of the spectra were simulated accurately, providing access to fast and reliable assignment of the enantiofacial preference. The results are highly consistent with available X‐ray data.
The first preparation of enantiopure 1‐methyl‐7‐oxabicyclo[2.2.1]heptan‐2‐one, a versatile chiral building block for terpenoids
Authors: Guan Yu‐Kun , Li Yu‐Lin 
Published: January 2005

AbstractMethods for the resolution of (±)‐1‐methyl‐7‐oxabicyclo[2.2.1]heptan‐2‐one 1, a versatile chiral building block for terpenoids, have been investigated. While no efficient result was obtained with kinetic resolution methods, both enantiomers of 1 were prepared optically pure for the first time via esterification of the reductive products of 1 with (+)‐mandelic acid and oxidation of the saponified products of diastereomer esters, in an overall yield of 70%. The absolute configurations of (−)‐1 and (+)‐1 were determined as (1S,4R)‐(−)‐1 and (1R,4S)‐(+)‐1 by the CD exciton chirality method and confirmed by Moshers 1H‐NMR method. Chirality 17:113–118, 2005. © 2005 Wiley‐Liss, Inc.
Photoeletrochemical Properties of TiO2 Films Modified with Gold Nanoparticles
Authors: Xu Hong , Liu Ling , Jia Neng‐Qin , Yang Jie , Yan Man‐Ming , Jiang Zhi‐Yu 
Published: January 2005

AbstractA nano‐Au modified TiO2 electrode was prepared via the oxidation of Ti sheet in flame and subsequent modification with gold nanoparticles. The results of SEM and TEM measurements show that the Au nanoparticles are well dispersed on TiO2 surface. A near 2‐fold enhancement in photocurrent was achieved upon the modification with Au nanoparticles. From the results of photocurrent and electrochemical impedance experiments it was found that the flatband potential of nano‐Au/TiO2 electrode negatively shifted about 100 mV in 0.5 mol/L Na2SO4 solutions compared with that of bare TiO2 electrode. The improvement of photoelectrochemical performance was explained by the inhibition for charge recombination of photo‐induced electrons and holes, and the promotion for interfacial charge‐transfer kinetics at nano‐Au/TiO2 composite film. Such nanometal‐semiconductor composite films have the potential application in improving the performance of photoelectrochemical solar cells.
Heat Capacity and Thermodynamic Properties of Myclobutanil
Authors: Sun Xiao‐Hong , Liu Yuan‐Fa , Tan Zhi‐Cheng , Jia Ying‐Qi , Wang Mei‐Han , Di You‐Ying 
Published: January 2005

AbstractThe low‐temperature heat capacities of myclobutanil (C15H17ClN4) were precisely measured with an automated adiabatic calorimeter over the temperature range from 78 to 368 K. The sample was observed to melt at (348.800 ±0.06) K. The molar enthalpy and entropy of the melting as well as the chemical purity of the substance were determined to be ΔfusHm (30931±11) J·mol−1, ΔfusSm (88.47±0.02) J·mol−1·K−1 and 99.41%, respectively. Further research of the melting process for this compound was carried out by means of DSC technique. The result was in agreement with that obtained from the measurements of heat capacities.
Microwave‐heating Synthesis and Gas Separation Performance of NaA Zeolite Membrane
Authors: Cheng Zhi‐Lin , Liu Zan , Wan Hui‐Lin 
Published: January 2005

AbstractThe paper presented novel synthesis of NaA zeolite membrane with good performance using microwave heating. The method involved two steps, prior seeding 120 nm of LTA crystals on substrate and then employing a secondary hydrothermal synthesis. Effects of seeding times, synthesis time and synthesis times were investigated in this work. The quality evaluation of membranes respectively used single component gases (H2 and N2) and H2/N2 (equivalent volume) mixture. The ideal H2/N2 selectivity increased from 1.90 of the substrate to 6.37 of the three‐stage synthesized membrane, which was distinctly higher than the corresponding Knudsen diffusion selectivity of 3.74. However, the real H2/N2 selectivity of the three‐stage synthesis was much lower than the corresponding ideal selectivity and close to the corresponding Knudsen diffusion selectivity of 3.74.
Synthesis of σ‐meso‐formylvinylchlorin and Benzoisobacterichlorin by Vilsmeier Reaction with Methyl Pyropheophorbide‐a
Authors: Wang Jin‐Jun , Wu Xu‐Ran , Shim Young‐Key 
Published: January 2005

AbstractFrom methyl pyropheophorbide‐a(MPPa,1), the vinyl group of methyl pyropheophorbide‐awas converted into alkylcarbonyl group by Grignard reaction and oxidization to give chlorins2,3and5. The Vilsmeier reaction of nickel 3‐substituent‐3‐devinylpyropheophorbide‐a(6), which was prepared by the metallation with nickel acetate, with 3‐dimethylamino‐acrolein/phosphoryl chloride (3‐DMA/POCl3) was carried out to give δ‐meso‐formylvinyl‐pyropheophorbide‐a(7) in good yield. The benzoisobacterichlorin (8) was obtained by the treatment of7bwith concentrated sulfuric acid.
Synthesis of New Silicon‐linked Lanthanocene Complexes and Their High Catalytic Activity for Methyl Methacrylate Polymerization with Nanometric Sodium Hydride as Co‐catalyst
Authors: Xie Xiao‐Min , Huang Ji‐Ling 
Published: January 2005

AbstractThe synthesis and characterization of four new silicon‐linked lanthanocene complexes with pendant phenyl groups on cyclopentadiene were reported. Based on the data of elemental analyses, MS and IR, the complexes were presumed to be unsolvated and dimeric complexes [Me2Si(C5H3CMe2C6H5)2LnCl]2 [Ln=Er (1), Gd (2), Sm (3), Dy (4)]. In conjunction with AlEt3 or sodium hydride as the co‐catalyst, these complexes could efficiently catalyze the polymerization of methyl methacrylate (MMA). When the nanometric sodium hydride was used as a co‐catalyst, the complexes were highly effective for the polymerization of MMA. At low temperature and in short time, in [Me2Si(C5H3CMe2C6H5)2LnCl]2/NaH (nanometric) system, the polymer was obtained in more than 80% yield and the molecular weight was greater than 105. The activity reached that of organolanthanide hydride as a single‐component catalyst. In [Me2Si(C5H3CMe2C6H5)2ErCl]2/NaH (nanometric) system, the effects of the molar ratio of MMA/catalyst and catalyst/co‐catalyst, and the temperature on polymerization were studied.
Effects of systemically administered NT‐3 on sensory neuron loss and nestin expression following axotomy
Authors: Kuo Lu‐Ting , Simpson Andrew , Schänzer Anne , Tse Jamie , An Shu‐Feng , Scaravilli Francesco , Groves Michael J. 
Published: January 2005

AbstractPrevious work has shown that administration of the neurotrophin NT‐3 intrathecally or to the proximal stump can prevent axotomy‐induced sensory neuron loss and that NT‐3 can stimulate sensory neuron differentiation in vitro. We have examined the effect of axotomy and systemic NT‐3 administration on neuronal loss, apoptosis (defined by morphology and activated caspase‐3 immunoreactivity), and nestin expression (a protein expressed by neuronal precursor cells) in dorsal root ganglia (DRG) following axotomy of the adult rat sciatic nerve. Systemic administration of 1.25 or 5 mg of NT‐3 over 1 month had no effect on the incidence of apoptotic neurons but prevented the overall loss of neurons seen at 4 weeks in vehicle‐treated animals. Nestin‐immunoreactive neurons began to appear 2 weeks after sciatic transection in untreated animals and steadily increased in incidence over the next 6 weeks. NT‐3 administration increased the number of nestin‐immunoreactive neurons at 1 month by two‐ to threefold. Nestin‐IR neurons had a mean diameter of 20.78 ± 2.5 μm and expressed the neuronal markers neurofilament 200, βIII‐tubulin, protein gene product 9.5, growth associated protein 43, trkA, and calcitonin gene‐related peptide. Our results suggest that the presence of nestin in DRG neurons after nerve injury is due to recent differentiation and that exogenous NT‐3 may prevent neuron loss by stimulating this process, rather than preventing neuron death. J. Comp. Neurol. 482:320–332, 2005. © 2005 Wiley‐Liss, Inc.
Expression of Trio, a member of the Dbl family of Rho GEFs in the developing rat brain
Authors: Ma Xin‐Ming , Huang Jian‐Ping , Eipper Betty A. , Mains Richard E. 
Published: January 2005

AbstractTrio, a member of the Dbl family of guanine nucleotide exchange factors (GEFs), has a series of spectrin repeats, two GEF domains, protein interaction domains, and a putative kinase domain, potentially important in neuronal axon guidance and cell migration. Most knowledge about Trio is based on studies of Caenorhabditis elegans and Drosophila, while the function of Trio in vertebrates is unclear. The aim of these experiments was to establish the patterns of Trio expression in the postnatal rat brain. During postnatal (P) development, high levels of Trio mRNA are found in the cerebral cortex, hippocampus, thalamus, caudate/putamen, and olfactory bulb, with lower levels in the septal nucleus, nucleus accumbens, amygdala, and hypothalamus. Except for the cerebellum, Trio mRNA in major brain areas is highest at P1, decreasing gradually during development, with low but detectable levels at P30. In P14 cerebral cortex, pyramidal neurons with strongly staining soma and dendrites are observed primarily in layer 5. In hippocampus, strong staining is observed in pyramidal neurons, granule cells, and isolated interneurons. Cerebellar Purkinje neurons exhibit intense staining in the soma and in extensive dendritic arbors at P7 and P14. Levels of Trio mRNA and the intensity of Trio immunostaining in cerebellar Purkinje cells increase from P1 to P30. Consistent with the in situ hybridization pattern, Western blot analyses show that Trio levels in the hippocampus and cortex are high at P1, decreasing until P30. The data suggest that Trio plays an important role during neuronal development. J. Comp. Neurol. 482:333–348, 2005. © 2005 Wiley‐Liss, Inc.
Dlx gene expression during chick inner ear development
Authors: Brown Stephen T. , Wang Juemei , Groves Andrew K. 
Published: January 2005

AbstractMembers of the Dlx gene family play essential roles in the development of the zebrafish and mouse inner ear, but little is known regarding Dlx genes and avian inner ear development. We have examined the inner ear expression patterns of Dlx1, Dlx2, Dlx3, Dlx5, and Dlx6 during the first 7 days of chicken embryonic development. Dlx1 and Dlx2 expression was seen only in nonneuronal cells of the cochleovestibular ganglion and nerves from stage 21 to stage 32. Dlx3 marks the otic placode beginning at stage 9 and becomes limited to epithelium adjacent to the hindbrain as invagination of the placode begins. Dlx3 expression then resolves to the dorsal otocyst and gradually becomes limited to the endolymphatic sac by stage 30. Dlx5 and Dlx6 expression in the developing inner ear is first seen at stages 12 and 13, respectively, in the rim of the otic pit, before spreading throughout the dorsal otocyst. As morphogenesis proceeds, Dlx5 and Dlx6 expression is seen throughout the forming semicircular canals and endolymphatic structures. During later stages, both genes are seen to mark the distal surface of the forming canals and display expression complementary to that of BMP4 in the vestibular sensory regions. Dlx5 expression is also seen in the lagena macula and the cochlear and vestibular nerves by stage 30. These findings suggest important roles for Dlx genes in the vestibular and neural development of the avian inner ear. J. Comp. Neurol. 483:48–65, 2005. © 2005 Wiley‐Liss, Inc.
Developmental expression of a tyramine receptor gene in the brain of the honey bee, Apis mellifera
Authors: Mustard Julie A. , Kurshan Peri T. , Hamilton Ingrid S. , Blenau Wolfgang , Mercer Alison R. 
Published: January 2005

AbstractThis study reveals that the tyramine receptor gene, Amtyr1, is expressed in the developing brain, as well as in the brain of the adult worker honey bee. Changes in levels of Amtyr1 expression were examined using Northern analysis. Age‐related increases in Amtyr1 transcript levels were observed not only during metamorphic adult development, but also in the brain of the adult worker bee. RNA in situ hybridization revealed the pattern of Amtyr1 expression. Cell bodies staining intensely for tyramine receptor‐gene transcript were observed throughout the somata rind, with well‐defined clusters of cells associated with developing mushroom bodies, optic lobes, and antennal lobes of the brain. Staining for Amtyr1 transcript was particularly intense within the three major divisions of mushroom body intrinsic neurons (outer compact, noncompact, and inner compact cells), suggesting that Amtyr1 is highly expressed in these structures. Activation of AmTYR1 receptors heterologously expressed in insect (Spodoptera frugiperda) cells led to a reduction in intracellular levels of cAMP similar to that reported for AmTYR1 receptors expressed in mammalian (HEK 293) cells (Blenau et al. [2000] J Neurochem 74:900–908). Taken together, these results suggest that AmTYR1 receptors may play a role in the developing brain as well as in the brain of the adult worker bee. The actions of tyramine are likely to be mediated, at least in part, via the cAMP‐signaling pathway. J. Comp. Neurol. 483:66–75, 2005. © 2005 Wiley‐Liss, Inc.
Using JavaNws to compare C and Java TCP‐Socket performance
Authors: Krintz Chandra , Wolski Rich 
Published: January 2005

AbstractAs research and implementation continue to facilitate high‐performance computing in Java, applications can benefit from resource management and prediction tools. In this work, we present such a tool for network round‐trip time and bandwidth between a user's desktop and any machine running a Web server (this assumes that the user's browser is capable of supporting Java 1.1 and above). JavaNws is a Java implementation and extension of a powerful subset of the Network Weather Service (NWS), a performance prediction toolkit that dynamically characterizes and forecasts the performance available to an application. However, due to the Java language implementation and functionality (portability, security, etc.), it is unclear whether a Java program is able to measure and predict the network performance experienced by C‐applications with the same accuracy as an equivalent C program. We provide a quantitative equivalence study of the Java and C TCP‐socket interface and show that the data collected by the JavaNws is as predictable as that collected by the NWS (using C). Copyright © 2001 John Wiley & Sons, Ltd.
Chaotic network synchronization with application to communications
Authors: Chow T. W. S. , Feng Jiu‐Chao , Ng K. T. 
Published: January 2005

AbstractChaotic signals are widely exploited for the spread spectrum communication technique. Synchronization of a chaotic communication system between a single point and multiple points is recognized as an essential issue. In this paper, a chaotic network synchronization scheme is proposed to tackle the problem of multi‐access synchronization. The proposed synchronization scheme enables the realization of a fast synchronization of multiple chaotic systems. In this paper, the proposed system is validated by application to direct‐sequence (DS) spread spectrum communication (SSC) with code division multiple access (CDMA). Promising results were obtained on the applications of speech, characters and image communications. The obtained results indicate that the proposed SSC is effective and reliable even under the situations of a noisy channel, and multi‐path interference. Copyright © 2001 John Wiley & Sons, Ltd.
An integrated routing and admission control mechanism for real‐time multicast connection establishment
Authors: Jia Xiaohua , Zhang Yongbing , Pissinou Niki , Makki Sam 
Published: January 2005

AbstractThere are two major difficulties in real‐time multicast connection setup. One is the design of an efficient distributed routing algorithm which optimizes the network cost of routing trees under the real‐time constraints. The other is the integration of routing with admission control into one single phase of operations. This paper presents a real‐time multicast connection setup mechanism, which integrates multicast routing with real‐time admission control. The proposed mechanism performs the real‐time admission tests on a cost optimal tree (COT) and a shortest path tree (SPT) in parallel, aiming at optimizing network cost of the routing tree under real‐time constraints. It has the following important features: (1) it is fully distributed; (2) it achieves sub‐optimal network cost of routing trees; (3) it takes less time and less network messages for a connection setup. Copyright © 2001 John Wiley & Sons, Ltd.
Screening of natural compounds and their derivatives as potential protein kinase C inhibitors
Authors: Tammela Päivi , Ekokoski Elina , García‐Horsman Arturo , Talman Virpi , Finel Moshe , Tuominen Raimo , Vuorela Pia 
Published: January 2005

AbstractProtein kinase C (PKC) isozymes are important signal transducers in a number of cellular responses that makes PKC inhibition a topical target for drug discovery. In this study, a set of natural compounds and their derivatives (43 in total) were screened to establish their potential inhibitory effects on PKC, exploiting kinase activity and [3H]‐phorbol ester binding assays. Statistical evaluation of the assays yielded signal‐to‐background, signal‐to‐noise, and Z′ values of 16.1, 11.3, and 0.62, respectively, for the kinase activity assay and 47.4, 15.9, and 0.73 for the binding assay, demonstrating their suitability for screening. Of the compounds investigated, the most potent PKC inhibitor was (−)‐epigallocatechin gallate (EGCG), which had an IC50 of 4.8 µM. In addition, (−)‐epicatechin gallate, dodecyl gallate, and the flavonoids myricetin, quercetin, rhamnetin, luteolin, isorhamnetin, and kaempferol were effective while naringin and scopoletin demonstrated negligible effects. None of the compounds was able to significantly inhibit the binding of phorbol ester to the regulatory domain of PKCα. The highest inhibition, 59%, was observed in the case of EGCG at a concentration of 150 µM. Taken together, nine PKC inhibitors were identified, none of which was able to compete with the binding of phorbol ester to PKCα, suggesting that the mechanism of PKC inhibition could be a result of binding to the catalytic domain of PKC. Drug Dev Res 63:76–87, 2004. © 2004 Wiley‐Liss, Inc.