bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics and Mechanism of Oxidation of Some Diols by Dihydroxydiperiodatoargentate(III) in Alkaline Medium
Authors: Shan Jin‐Huan , Li Sheng‐Min , Huo Shu‐Ying , Shen Shi‐Gang , Sun Han‐Wen 
Published: April 2006

AbstractThe kinetics of oxidation of ethylene glycol and 1,3‐butylene glycol by dihydroxydiperiodatoargentate(III) in alkaline medium have been studied by spectrophotometry in the range of 298.2–318.2 K. It is shown that the reaction was first order with respect to each reductant and Ag(III), and kobs increased with an increase of [OH−]. A plausible mechanism of reaction involving a pre‐equilibrium of adduct formation between complex and reductants was proposed, which could be applied to explain all experimental phenomena, and the activation parameters of the rate‐determining step have been also calculated.
Charge Migration in DNA: A Double Stranded Model
Authors: Bao Han , Lu Jing , Fan Kang‐Nian 
Published: April 2006

AbstractIn particular, charge migration phenomena in DNA have attracted much interest because of relevance to the generation of damage and mutations which play important roles in most of life processes. In this paper a theory method was presented in which the DNA chain was treated as a double‐stranded system, and the charge migration in DNA based on the donor‐bridge‐acceptor system was investigated by this model. After having obtained the Hamiltonian, the effects of the surrounding were explained and calculated. The double‐strand calculation could lead to good exponential decay curves and this time two different falloff parameters were found respectively before and after 3 or 4 AT base pair bridge lengths as prediction. Lately theoretical study showed this result by addition of more parameter, and sequence effect was then concentrated on. The difference of transfer integral caused the different decay rate of unlike sequences, but bridge length was still proved to be the main factor on the decay rates.
Cation Guided Assembly: Crystal Structures of Two Ag(I) Complexes in Versatile Dimensionalities with Different Counter Cations
Authors: Wang Jiang‐Yun , Gu Wen , Wang Wen‐Zhen , Liu Xin , Liao Dai‐Zheng 
Published: April 2006

AbstractAssembly of [Ag(CN)2]− units with M(II)‐diamine complex cations [Cu(LN‐N)2]2+, where LN‐N represents 1,2‐diaminopropane (pn) and ethylenediamine (en), afforded two complexes, [Cu(pn)2][Ag2(CN)4] (1) and [Cu(en)2][Ag3(CN)5] (2), which were characterized by elemental analysis, IR, UV‐Vis and ESR spectra. Single crystal X‐ray analyses show that these complexes have 2D and 3D architectures through silver‐silver interactions and other weak interactions. The luminescence behaviors of the two complexes were also studied by means of emission spectra.
Kinetics of Thermal Decomposition of Zn1–xMnxC2O4·2H2O in Air
Authors: Cong Chang‐Jie , Hong Jian‐He , Luo Shi‐Ting , Tao Hai‐Bo , Zhang Ke‐Li 
Published: April 2006

AbstractThermal decomposition processes taking place in solid state complex of Zn1−xMnxC2O4·2H2O have been investigated in air using TG‐DTG/DTA, XRD and TEM techniques. TG‐DTG/DTA curves showed that the decomposition proceeded through two well‐defined steps with DTA peaks closely to correspond to the weight loss. XRD and TEM showed that the final decomposition product of Zn1–xMnxC2O4·2H2O was Zn1–xMnxO and most of the individual particles were of size 10–13 nm. Kinetics analysis of Zn1–xMnxC2O4·2H2O decomposition steps was performed under nonisothermal conditions, the activation energies were estimated by Friedman and Flynn‐Wall‐Ozawa (FWO) methods, and the most probable kinetic model has been estimated with multiple linear regression method. The activation energies for the two decomposition steps of Zn1–xMnxC2O4·2H2O were 155.7513 and 215.9397 kJ/mol, respectively.
Synthesis of Two Natural Oleanolic Acid Saponins
Authors: Li Chun‐Xia , Zang Jing , Wang Peng , Zhang Xiu‐Li , Guan Hua‐Shi , Li Ying‐Xia 
Published: April 2006

Abstract3‐O‐[β‐D‐Glucopyranosyl‐(1→3)‐α‐L‐arabinopyranosyl]‐oleanolic acid‐28‐O‐[β‐D‐glucopyranosyl] ester 1 was synthesized concisely by a convergent strategy. Using stepwise fashion for the synthesis of saponin 2, 3‐O‐{[β‐D‐glucopyranosyl‐(1→2)]‐[α‐L‐arabinopyranosyl‐(1→3)]‐α‐L‐arabinopyranosyl}‐oleanolic acid‐28‐O‐(β‐ D‐glucopyranosyl) ester, an abnormal phenomenon, that the terminal arabinosyl residue took the 1C4 conformation instead of typical 4C1 form, was observed. Deprotection or heating could not resume the normal conformation, which resulted in the product of 2′ not 2.
Synthesis and Crystal Structure of a Tetranuclear Cubane‐like Nickel(II) Complex with 2‐Hydroxymethyl‐N‐salicylideneaniline
Authors: Liu Hui‐Yan , Wang Hai‐Ying , Shi Da‐Qing , Tian Jin‐Lei 
Published: April 2006

AbstractThe tetranuclear cubane‐like complex, [NiL(EtOH)]4·0.5EtOH (1) with tridentate Schiff base ligand (H2L=2‐Hydroxymethyl‐N‐salicylideneaniline) has been synthesized and its crystal structure and spectroscopic properties have been studied. The complex consists of a tetranuclear (NiO)4 cubane core, of which four nickel(II) ions are bridged by μ3‐alkoxide group and each nickel(II) ion is coordinated to three μ3‐alkoxide oxygen atoms, one imino nitrogen atom and one phenoxide oxygen atom from Schiff base ligand, and further ligated by one EtOH molecule, completing a distorted octahedral geometry.
Investigation on Voltammetric Behavior of Camptothecin and Its Analytical Application
Authors: Zheng Jian‐Bin , Meng Zu‐Chao , Liu Bo , Zhang Hong‐Fang 
Published: April 2006

AbstractThe voltammetric behavior of camptothecin (CPT) in Britton‐Robinson (B‐R) buffer solutions (pH 2.09–9.07) was studied by the means of linear sweep voltammetry (LSV), cyclic voltammetry (CV) and normal pulse voltammetry (NPV) at a hanging mercury drop electrode. In different pH range of B‐R buffer solutions, CPT could cause three reduction waves. In B‐R buffer solutions (pH 2.09–5.46), wave P1 yielded by CPT was a two‐electron wave. Between pH 6.01 and 9.07, CPT could yield two reduction waves P2 and P3. In addition, the pure CPT obtained from camptotheca acumina grown only in China was determined by NPV, and a linear response was observed in the range of 2.0×10−3–4.0×10−2 mmol·L−1 with a 0.9991 correlation coefficient and a 8.0×10−4 mmol·L−1 detection limit for CPT.
Covalent Functionalization of Multiwalled Carbon Nanotubes with Poly(acrylic acid)
Authors: Liu Yan‐Xin , Du Zhong‐Jie , Li Yan , Zhang Chen , Li Hang‐Quan 
Published: April 2006

AbstractCovalent functionalization of multiwalled carbon nanotubes (MWNT) with poly(acrylic acid) has been successfully achieved via grafting of poly(acryloyl chloride) on nanotube surface by esterification reaction of acyl chloride‐bound polymer with hydroxyl functional groups present on acid‐oxidized MWNT and hydrolysis of polymer attached to nanotubes. Polymer‐functionalized MWNT could possess remarkably high solubility in water, and their aqueous solution was very stable without any observable black deposit for a long time. Characterizations of such functionalized MWNT samples using Fourier transform infrared spectrometer, transmission electron microscopy and nuclear magnetic resonance techniques indicated that poly(acrylic acid) was covalently attached to the surface of MWNT.
Crystal Structure and Photochromism of a Novel Organic Compound Condensed by Pyrazolone with Thiosemicarbazide
Authors: Liu Guang‐Fei , Liu Lang , Jia Dian‐Zeng , Zhang Li 
Published: April 2006

AbstractA new photochromic organic compound of thiosemicarbazone, 4‐(p‐bromo‐α‐methylaminothiocarbonyl hydrazonobenzal)‐2,5‐dihydro‐3‐methyl‐5‐oxo‐1‐phenyl pyrazole, was synthesized and characterized by elemental analyses, IR, 1H NMR spectra, and X‐ray single‐crystal diffraction analysis. The compound exhibited an interesting photochromism in the solid state when irradiated by ultraviolet light at 365 nm. The photochromic kinetics was studied by the time‐dependent powder UV‐Vis reflectance spectra. The intermolecular and intramolecular hydrogen‐bonding interactions may be responsible for the photochromic phenomenon.
Improving the Enzyme Catalytic Efficiency Using Ionic Liquids with Kosmotropic Anions
Authors: Zhao Hua , Campbell Sophia , Solomon Jonathan , Song Zhi‐Yan , Olubajo Olarongbe 
Published: April 2006

AbstractThe kosmotropicity of cations and anions in ionic liquids has a strong influence on the enzyme catalytic efficiency in aqueous environments. The kosmotropic anion CF3COO− seemed to activate the protease, and the chaotropic anions tended to destabilize the enzyme.
Synthesis and Investigation of Soluble Polymer‐supported Dendrimers
Authors: Xie Cheng , Lu Cui‐Fen , Chen Zu‐Xing , Yang Gui‐Chun 
Published: April 2006

AbstractPoly(ethylene glycol) (PEG)‐supported dendrimers have been synthesized using 2,4,6‐trichloro‐1,3,5‐triazine (TCT) as dendrons and tris(hydroxymethyl)aminomethane as linkers with high loading capacity, excellent solubility and thermal stability by divergent method. The new synthesized PEG‐supported G2.0 dendrimer has 10 times as large functional group loading capacity as commercial PEG3400 with overall yield 44.0%.
Preoperative steroid pulse therapy for invasive thymoma
Authors: Kobayashi Yoshihiro , Fujii Yoshitaka , Yano Motoki , Sasaki Hidefumi , Yukiue Haruhiro , Haneda Hiroshi , Suzuki Eriko , Endo Katsuhiko , Kawano Osamu 
Published: April 2006

AbstractBACKGROUNDGlucocorticoid was used in thymomas. The purpose of the study was to evaluate the efficacy of intravenous high‐dose glucocorticoid (steroid pulse) therapy in patients with previously untreated advanced thymoma. Causes were also sought for a possible underlying mechanism of the effect of steroid on thymoma.METHODSSeventeen patients with invasive thymoma who had not received previous chemotherapy or radiation therapy were enrolled in the study. All cases were treated with 2 courses of glucocorticoid therapy before surgery. Tumor response was assessed by computed tomography (CT) scan 1 week after the steroid pulse therapy. Lymphocytes associated with thymoma were analyzed for their CD4/CD8 phenotype and glucocorticoid receptor (GR). TdT‐mediated dUTP‐biotin nick‐end labeling (TUNEL) staining was used to analyze the apoptotic lymphocytes and epithelial cells.RESULTSThe overall response rate to the steroid pulse therapy was 47.1% (8 of 17). The reduction in tumor size was most prominent in type B1 thymomas; there were significant differences between type AB and type B1 thymomas (P = .0234) and type B1 and type B3 thymomas (P = .0068). The reduction in tumor size was accompanied with a marked reduction in the CD4+8+ double‐positive immature thymocytes that expressed higher levels of glucocorticoid receptor. Apoptotic changes were observed in both neoplastic epithelial cell and lymphocyte components after glucocorticoid therapy.CONCLUSIONSThe efficiency of preoperative steroid pulse therapy in type B1 thymoma was most prominent, which is probably related to the specific effect on GR‐rich CD4+8+ double‐positive immature lymphocytes, which are abundant in this type of thymoma. Cancer 2006. © 2006 American Cancer Society.
Water Formation on Pt and Pt‐based Alloys: A Theoretical Description of a Catalytic Reaction
Authors: Jacob Timo , Goddard William A. 
Published: April 2006

AbstractIn the past, the modeling of catalytic processes was limited by the size and complexity of the systems involved. However, the enormous progress in both computer power and theoretical methods has made computational modeling a valuable tool in increasing our knowledge of catalytic reactions on the atomic scale. While complex reactions can be studied by dividing the overall reaction into a series of steps calculable by quantum mechanics, the combination with methods appropriate for larger time and length scales enables the gap between these regimes to be bridged. This provides a more realistic modeling of the experimental system and allows important environmental effects such as solvation to be taken into account. In this Minireview we describe some of the main theoretical methodologies that are used to study catalytic properties and reactions on surfaces. Using these methods, we study the seemingly simple reaction of water formation out of hydrogen and oxygen on Pt and Pt/Ni alloy catalysts. To provide a more realistic description we also discuss the interesting effects determined by hydrating the system or using alloy nanoparticles rather than extended surfaces.
Hypomagnesemia, oxidative stress, inflammation, and metabolic syndrome
Authors: Guerrero‐Romero Fernando , Rodríguez‐Morán Martha 
Published: April 2006

AbstractBackgroundAlthough hypomagnesemia, oxidative stress, and inflammation are involved in the pathogenesis of cardiovascular diseases, there is not a previous description concerning their potential interaction; thus, the aim of this study was to examine the relationship between metabolic syndrome (MetS), hypomagnesemia, inflammation, and oxidative stress.MethodsCase‐control design study. Incident cases of MetS (84 women and 63 men) were compared with healthy control subjects (163 women and 131 men) matched by age and gender. MetS was diagnosed according to the Adult Treatment Panel III (ATP III) criterion. Oxidative stress was defined by serum malondialdehyde concentration (MDA) ≥50 mg/dL, low‐grade chronic inflammation by C‐reactive protein (CRP) serum levels ≥3 mg/L, and hypomagnesemia by serum magnesium concentrations ≤1.8 mg/dL.ResultsMultivariate analysis adjusted by age, sex, body mass index, waist‐to‐hip ratio, and total adiposity showed a strong association between MetS and hypomagnesemia (OR 1.9; 95% CI 1.3–7.1), inflammation (OR 1.7; 95% CI 1.4–8.4), and oxidative stress (OR 1.4; 95% CI 0.9–12.6). Additional adjustment by CRP levels showed that MetS remained associated to hypomagnesemia (OR 1.4; 95% CI 1.1–5.9) but not to oxidative stress (OR 1.1; 95% CI 0.9–5.9), and adjusted by MDA levels, MetS remained strongly associated to hypomagnesemia (1.6; CI 95% 1.1–7.4), but not to inflammation (OR 1.05; 95% CI 0.97–14.2). Adjusted by serum magnesium levels, inflammation (OR 1.2; 95% CI 1.1–9.1) and oxidative stress (OR 1.1; 95% CI 1.1–9.7) were slightly associated to MetS.ConclusionsThe interaction of inflammation and oxidative stress is related and increases the risk for MetS, whereas serum magnesium levels and MetS are independently associated. Copyright © 2006 John Wiley & Sons, Ltd.
Ti/TiO2 Electrode Preparation Using Laser Anneal and Its Application to Determination of Chemical Oxygen Demand
Authors: Li Jiaqing , Zheng Lei , Li Luoping , Shi Guoyue , Xian Yuezhong , Jin Litong 
Published: April 2006

AbstractA method for Ti/TiO2 photoelectrode preparation using laser calcination instead of oven calcination process was introduced. The prepared TiO2 film was investigated by X‐ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and amperometry, and it was found that the prepared electrode mainly consisted of anatase TiO2 nanoparticles on its surface and exhibited a superior photocatalytic activity. The electrode was employed as a sensor to measure chemical oxygen demand (COD) of the wastewater. The measuring principle was based on the photocurrent responses of the electrode which were proportional to the COD values. Under the optimized experimental conditions, the linear range was 50–2000 mg L−1, and the detection limit was 16 mg L−1 (S/N=3). This method was characterized by short analysis time, simplicity, low environmental impact and long lifetime of the sensor. Additionally, the COD values obtained from the proposed and conventional methods agreed well as demonstrated by the high significant correlation between the two sets of COD values (R=0.9895, n=25).
Variability in sediment supply, transfer and deposition in an upland torrent system: Iron Crag, northern England
Authors: Johnson R. M. , Warburton J. 
Published: April 2006

AbstractResearch into torrent erosion has focused on bedload transport dynamics, debris flow propagation during flood events, and fan sedimentation. Studies have frequently been biased towards specific events and have not considered sediment delivery in the catchment as a whole. The aim of this study is to examine spatial variations and process controls on sediment transfer in an upland torrent system (hillslopes, channel and fan).The study site is Iron Crag, a small torrent system (catchment area 2·4 ha) situated in the northern Lake District, UK. Particle size analysis of hillslope sediments trapped during transport suggests sediment calibre is controlled primarily by sediment source. Freeze–thaw and rainfall processes impart a weak but recognizable size sorting signature on the trapped sediments. However, these variations are less significant in determining sediment supply to the basal fan, than those operating in the channel system. Channel sediment movement is strongly influenced by storm events, the type of flow process (debris flow or fluvial flow), the sediment characteristics, and the local channel topography. The importance of the channel–fan coupling is clearly demonstrated in that more than 90 per cent of fan sedimentation is derived from channel sediment sources. Copyright © 2006 John Wiley & Sons, Ltd.
Cirque development in a steadily uplifting range: rates of erosion and long‐term morphometric change in alpine cirques in the Ben Ohau Range, New Zealand
Authors: Brook Martin S. , Kirkbride Martin P. , Brock Ben W. 
Published: April 2006

AbstractThe intractable obstacle to understanding cirque evolution has been the lack of an independent timescale against which to measure morphometric change. By using known rates of transport and uplift of the Southern Alps, combined with the oxygen isotope record contained in marine sediments, it is possible to estimate the duration of glacial occupancy of cirques in the Ben Ohau Range. The pattern is one of very limited glaciation of the southern range, with glacial occupancy increasing northwards. Map‐based measurement of 18 morphometric properties in each of 92 cirques reveals systematic northward trends in cirque size, form and altitude, which are explained as reflections of increasing cirque ‘age’ (i.e. length of glacial occupancy). Thus, the validity of space–time substitution is demonstrated rather than assumed, and morphometric trends define evolutionary stages of cirque development. For cirques with up to c. 750 ka occupancy, rates of downcutting average 0·29 mma−1 and headwall retreat 0·44 mm a−1. There is no indication of attainment of an equilibrium form within this time: both cirque size and form continue to evolve throughout, with few parameters showing a convergence of value with cirque ‘age’. Some morphometric parameters perform much better than others: the k coefficient of the long‐profile descriptor is the most powerful predictor of cirque ‘age’, and simple measures correlate better than derived measures (e.g. ratios of dimensions). The trends identified concur with some previously published ideas, but for the first time provide empirically quantified rates of change at an appropriate timescale. Copyright © 2006 John Wiley & Sons, Ltd.
Scale relationships in hillslope runoff and erosion
Authors: Parsons Anthony J. , Brazier Richard E. , Wainwright John , Powell D. Mark 
Published: April 2006

AbstractEight runoff plots, located within a small catchment within the Walnut Gulch Experimental Watershed, southern Arizona, were constructed to test the argument that sediment yield (kg m−2) decreases as plot length increases. The plots ranged in length from 2 m to 27·78 m. Runoff and sediment loss from these plots were obtained for ten natural storm events. The pattern of sediment yield from these plots conforms to the case in which sediment yield first increases as plot length increases, but then subsequently decreases. Data from the present experiment indicate that maximum sediment yield would occur from a plot 7 m long. Analysis of both runoff and sediment yield from the plots indicates that the relationship of sediment yield to plot length derives both from the limited travel distance of individual entrained particles and from a decline in runoff coefficient as plot length increases. Particle‐size analysis of eroded sediment confirms the role of travel distance in controlling sediment yield. Whether in response to the finite travel distance of entrained particles or the relationship of runoff coefficient to plot length, the experiment clearly demonstrates that the erosion rates for hillslopes and catchments cannot be simply extrapolated from plot measurements, and that alternative methods for estimating large‐area erosion rates are required. Copyright © 2006 John Wiley & Sons, Ltd.
The influence of grazing on vegetation, soil properties and stream discharge in a small Dartmoor catchment, southwest England, UK
Authors: Meyles E. W. , Williams A. G. , Ternan J. L. , Anderson J. M. , Dowd J. F. 
Published: April 2006

AbstractIntensive grazing has been responsible for environmental degradation of moorland landscapes over the last 50 years. Anecdotal evidence on Dartmoor, UK, for example, has suggested that it is particularly associated with a greater frequency of large floods, lower baseflow and a greater occurrence of erosion. A study was therefore conducted at Holne Moor, a small catchment on east Dartmoor, to investigate the impacts of grazing animals on hillslope hydrology and stream discharge. The vegetation in the study area ranged from heather (Calluna vulgaris), in areas with low grazing intensity, to short grass with occasional erosion scars visible associated with larger sheep numbers. The physical characteristics of the topsoil beneath heather species were very different compared with short grass. This was not due so much to the direct physical impact of grazing animals, but indirectly to the chemical and biological differences brought about by changes in vegetation response and soil structure. The experiment at Holne Moor indicated that soil water content on the hillslope was linked directly to the stream's rainfall–runoff response via the soil water pathways. In relatively dry conditions, the soil water content is mainly determined by local factors such as vegetation. In wet periods, non‐local influences such as slope and contributing area are more important. A soil water content threshold of around field capacity separated the two conditions. A comparison between soil physical properties and soil moisture under different vegetation types indicated that this ‘runoff’ threshold between dry and wet states is lower in heavily grazed areas. It is argued that more intense grazing causes conditions suited to the increased delivery of soil water to rapid flowpaths such as sheep tracks and other rapid routes which connect the source of this hillslope water to the contributing areas during large floods. Any alteration of vegetation and soil properties due to management causes a substantial increase in ‘active’ source areas and therefore discharge during large storm events even before any erosion occurs. Copyright © 2006 John Wiley & Sons, Ltd.
Gallager bounds on the performance of maximum‐likelihood decoded linear binary block codes in AWGN interference
Authors: Yousefi Shahram 
Published: April 2006

AbstractPerformance evaluation of maximum‐likelihood (ML) soft‐decision‐decoded binary block codes is usually carried out using bounding techniques. Many tight upper bounds on the error probability of binary codes are based on the so‐called Gallager's first bounding technique (GFBT). In this method, Gallager bisects the error probability to the joint probability of error and noise residing in a region ℜ (here referred to as the Gallager region) plus joint probability of error and noise residing in the complement of ℜ (also referred to as regions of many and few errors, respectively); where ℜ is a volume around the transmitted codeword. In this tutorial review, a comprehensive study of a number of upper bounds on the error probability of ML decoding of binary codes based on GFBT is provided. For some bounds, their applicability to other schemes is also pointed out and argued. We also provide an overview of bounds based on Gallager's second bounding technique (GSBT) and discuss some of their relations and interconnections. Copyright © 2006 AEIT