bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rate coefficients for the reaction of OH with OClO between 242 and 392 K
Authors: Gierczak Tomasz , Burkholder James B. , Ravishankara A. R. 
Published: February 2006

AbstractRate coefficients are reported for the gas phase reaction of OH with OClO over the temperature range 242–392 K at 25, 50, and 100 Torr (He). Kinetic measurements were made using pulsed laser photolysis with laser induced fluorescence detection of the OH radical. The measured rate coefficients were independent of pressure and are well represented by k1(T) = (1.43 ± 0.3) × 10−12 exp(597 ± 36/T) cm3 molecule−1 s−1 (k1(298 K) = 1.06 × 10−11 cm3 molecule−1 s−1). The quoted uncertainties are 2σ (95% confidence level) and include estimated systematic errors. Discrepancies with the previous OH + OClO rate coefficient measurement by Poulet et al. (Int J Chem Kinet 1986, 18, 847–859) are discussed. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 234–241, 2006
Experimental and modeling study of the oxidation of xylenes
Authors: Battin‐Leclerc F. , Bounaceur R. , Belmekki N. , Glaude P. A. 
Published: February 2006

AbstractThis paper describes an experimental and modeling study of the oxidation of the three isomers of xylene (ortho‐, meta‐, and para‐xylenes). For each compound, ignition delay times of hydrocarbon–oxygen–argon mixtures with fuel equivalence ratios from 0.5 to 2 were measured behind reflected shock waves for temperatures from 1330 to 1800 K and pressures from 6.7 to 9 bar. The results show a similar reactivity for the three isomers. A detailed kinetic mechanism has been proposed, which reproduces our experimental results, as well as some literature data obtained in a plug flow reactor at 1155 K showing a clear difference of reactivity between the three isomers of xylene. The main reaction paths have been determined by sensitivity and flux analyses and have allowed the differences of reactivity to be explained. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 284–302, 2006
UV absorption spectra and self‐reaction rate constants for primary peroxy radicals arising from the chlorine‐initiated oxidation of carbonyl compounds
Authors: Crane J. P. Le , Villenave E. 
Published: February 2006

AbstractA flash photolysis setup coupled to UV absorption spectrometry detection was used to measure the UV absorption spectra of the (CH3)2(CH2O2.)CC(O)C(CH3)3 and (CH3)2(CH2O2.)CC(O)CH3 radicals between 207 and 290 nm. The self‐reaction rate constants of these radicals were measured at 298 K: k((CH3)2(CH2O2.)CC(O)C(CH3)3 + (CH3)2(CH2O2.)CC(O)C(CH3)3) = (4.57 ± 0.38) × 10−12 cm3 molecule−1 s−1; k((CH3)2(CH2O2.) CC(O)CH3 + (CH3)2(CH2O2.)CC(O)CH3) = (4.77 ± 0.35) × 10−12 cm3 molecule−1 s−1, where quoted uncertainties only represent 2σ errors. Because of the similarities in both UV spectra and self‐reaction kinetics between (CH3)2(CH2O2.)CC(O)C(CH3)3 and (CH3)2(CH2O2.)CC(O)CH3 radicals, it was suggested to extend this results to all (CH3)2(CH2O2.)CC(O)R peroxy radicals (with R = H, alkyl), arising from the chlorine‐initiated oxidation of carbonyl compounds. This trend has been tested successfully in the case of the Cl‐initiated oxidation of pivalaldehyde (Le Crâne et al., J Phys Chem A 2004, 108, 795). © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 276–283, 2006
The nature and extent of landscape change under land resettlement programmes in Zimbabwe
Authors: Elliott J. A. , Burnside N. G. , Broomhead T. , Kinsey B. H. , Kwesha D. 
Published: February 2006

AbstractIssues of land and further resettlement are central within the inter related crises that Zimbabwe is currently understood to be experiencing. This paper presents objective data that has not been available to date, concerning the landscape outcomes of the resettlement programme in Zimbabwe as it was implemented in the first two decades after independence. Sequential aerial photograph interpretation and GIS techniques are used to document and explore spatial patterns of resource use, landscape structure and change. Based on 21 resettlement villages across three scheme areas, the analysis explicitly considers the role of national drivers (of the relatively consistent policy and procedures during that time), of agro‐ecology and of multidirectional transformations at the village level to raise understanding of these outcomes. The implications of these findings and the value of the methodological techniques for the design and monitoring of further resettlement in the country and the wider region are suggested. Copyright © 2006 John Wiley & Sons, Ltd.
Land use and soil erosion in the upper reaches of the Yangtze River: some socio‐economic considerations on China's Grain‐for‐Green Programme
Authors: Long H. L. , Heilig G. K. , Wang J. , Li X. B. , Luo M. , Wu X. Q. , Zhang M. 
Published: February 2006

AbstractSoil erosion in the upper reaches of the Yangtze River in China is a major concern and the Central Government has initiated the Grain‐for‐Green Programme to convert farmland to forests and grassland to improve the environment. This paper analyses the relationship between land use and soil erosion in Zhongjiang, a typical agricultural county of Sichuan Province located in areas with severe soil erosion in the upper reaches of the Yangtze River. In our analysis, we use the ArcGIS spatial analysis module with detailed land‐use data as well as data on slope conditions and soil erosion. Our research shows that the most serious soil erosion is occurring on agricultural land with a slope of 10∼25 degrees. Both farmland and permanent crops are affected by soil erosion, with almost the same percentage of soil erosion for corresponding slope conditions. Farmland with soil erosion accounts for 86·2 per cent of the total eroded agricultural land. In the farmland with soil erosion, 22·5 per cent have a slope of < 5 degrees, 20·3 per cent have a slope of 5∼10 degrees, and 57·1 per cent have a slope of > 10 degrees. On gentle slopes with less than 5 degrees inclination, some 6 per cent of the farmland had strong (5000∼8000 t km−2 y−1) or very strong (8000∼15000 t km−2 y−1) erosion. However, on steep slopes of more than 25 degrees, strong or very strong erosion was reported for more than 42 per cent of the farmland. These numbers explain why the task of soil and water conservation should be focused on the prevention of soil erosion on farmland with steep or very steep slopes. A Feasibility Index is developed and integrated socio‐economic assessment on the feasibility of improving sloping farmland in 56 townships and towns is carried out. Finally, to ensure the success of the Grain‐for‐Green Programme, countermeasures to improve sloping farmland and control soil erosion are proposed according to the values of the Feasibility Index in the townships and towns. These include: (1) to terrace sloping farmland on a large scale and to convert farmland with a slope of over 25 degrees to forests or grassland; (2) to develop ecological agriculture combined with improving the sloping farmland and constructing prime farmland and to pay more attention to improving the technology for irrigation and cultivation techniques; and (3) to carry out soil conservation on steep‐sloping farmland using suggested techniques. In addition, improving ecosystems and the inhabited environment through yard and garden construction for households is also an effective way to prevent soil erosion. Copyright © 2006 John Wiley & Sons, Ltd.
A laboratory study on the relative stability of the check‐dam system in the Loess Plateau, China
Authors: Xu X. Z. , Zhang H.‐W. , Wang G.‐Q. , Peng Y. , Zhang O. Y. 
Published: February 2006

AbstractThe building of check‐dams is one of the most effective measures for the conservation of soil and water in the Loess Plateau of China, and the hydro‐sedimentologic balance is the most important factor influencing the relative stability of the check‐dam systems. This means that the soil and water in small watersheds controlled by the check‐dams will be absorbed internally, without the need for raising the height of the dams, if some given parameters have reached certain values. A runoff simulation experiment for a single check‐dam and a rainfall simulation experiment for the whole check‐dam system has been conducted, and the runoff/rainfall intensity and the parameter RV were determined through the annual erosion rate of the prototype watershed. The results indicated that the raising of the dam‐land altitude became slower, and the mean gradient of the gully was kept at a constant. The main reasons causing the check‐dam to show a good relative stability are the enlarging of the dam‐land area, the alleviating of erosion by the check‐dam, and the auto‐stabilizing mechanism of the gullies.This study presents a kind of scale‐down model experiment in which the ratio of the model geomorphological variable to the corresponding prototype variable keeps constant after the determinate runs of rainfalls, so that the soil and water erosion processes of the prototype could be monitored from the results of the model experiment. Four measures have been suggested for ensuring this ratio is a constant: (1) A bare‐land model with an appropriate erosion rate should be used in the experiment. (2) Dimensions of the landform, including the check‐dam, should normally be scaled down according to the prototype watershed. (3) Soil similar to those of the prototype should be used. (4) The antecedent water content before each rainfall simulation should be kept constant. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis of Novel Monomers and Copolymers from 1‐Vinylpyrrolidin‐2‐one: Attractive Materials for Drug Delivery Systems?
Authors: Engström Jonas U. A. , Lindgren Lars J. , Helgee Bertil 
Published: February 2006

AbstractSummary: Polyvinylpyrrolidone (PVP) is a synthetic, non‐toxic, water‐soluble polymer commonly used in a wide range of applications including several pharmaceutical applications. One example of an important application is the controlled release and delivery of therapeutic agents into sites of inflammation or tumours. However, PVP lacks reactive groups, which limits the possibility of adding new functions to the polymer in order to modify its physical and chemical properties. Furthermore, large differences in radical reactivity between 1‐vinylpyrrolidin‐2‐one (NVP) and most other monomers lead to compositional drift during copolymerization. This complicates the introduction of reactive groups into the polymer using this method. Monomers that are derivatives of NVP itself are expected to show smaller differences in radical reactivity and therefore provide a way of preparing PVP with adjustable properties. Here we present the synthesis of five NVP‐based monomers and their use in the preparation of functional PVP with adjustable properties in terms of solubility, loading of functional groups, and molar mass. The results show the possibility of tailoring PVP for different biomedical applications e.g. drug delivery systems.Copolymers from 1‐vinylpyrrolidin‐2‐one.magnified imageCopolymers from 1‐vinylpyrrolidin‐2‐one.
Synthesis and Micellization Properties of Novel Symmetrical Poly(ε‐caprolactone‐b‐[R,S] β‐malic acid‐b‐ε‐caprolactone) Triblock Copolymers
Authors: Coulembier Olivier , Degée Philippe , Dubois Philippe 
Published: February 2006

AbstractSummary: A four‐step strategy to synthesize well‐defined amphiphilic poly(ε‐caprolactone‐b‐[R,S] β‐malic acid‐b‐ε‐caprolactone) triblock copolymers [P(CL‐b‐MLA‐b‐CL)], which combines the anionic polymerization of [R,S] benzyl β‐malolactonate (MLABz), and the coordination‐insertion ring‐opening polymerization (ROP) of ε‐caprolactone (CL), followed by the selective removal of benzyloxy protective groups of the central poly(malolactonate) block is described. The first step involves MLABz initiated by potassium 11‐hydroxydodecanoate in the presence of 18‐crown‐6 ether. This step was carried out at 0 °C with an initial monomer concentration of 0.2 mol · L−1 in order to limit the occurrence of undesirable transfer and termination reactions by proton abstraction. After selective reduction of the carboxylic acid end‐group of the resulting α‐hydroxy, ω‐carboxylic poly([R,S] benzyl β‐malolactonate) leading to an α,ω‐dihydroxy PMLABz, the polymerization of CL was initiated by each hydroxyl end‐groups previously activated by AlEt3. Finally, after catalytic hydrogenation of the benzyl ester functions, the P(CL‐b‐MLA‐b‐CL) triblock copolymer was recovered and the amphiphilic character evidenced by UV spectroscopy. As demonstrated, the CMC of these new P(CL‐b‐MLA‐b‐CL) triblock copolymer is higher by one order of magnitude than that of a P(MLA‐b‐CL) diblock copolymer of similar composition.Concentration dependence of pyrene I338/I335 intensitiy ratio for P(MLA‐b‐CL) diblock and P(CL‐b‐MLA‐b‐CL) triblock copolymers in water.magnified imageConcentration dependence of pyrene I338/I335 intensitiy ratio for P(MLA‐b‐CL) diblock and P(CL‐b‐MLA‐b‐CL) triblock copolymers in water.
Gonadotropins affect Oct‐4 gene expression during mouse oocyte growth
Authors: Monti Manuela , Garagna Silvia , Redi CarloAlberto , Zuccotti Maurizio 
Published: February 2006

AbstractThe transcription factor Oct‐4 is required for the maintenance of stem cells pluripotency and is involved in the regulation of the expression of a number of developmental genes. Oct‐4 is also expressed in the female gamete during folliculogenesis, but the role it plays is largely unknown. Its upstream and promoter regions have some characteristic features that make this gene a possible target of hormonal regulation. To further our understanding of Oct‐4 gene expression during oocyte growth, we tested whether changes to the hormonal milieu of the ovary may affect its transcription. Using a semi‐quantitative single‐cell‐sensitive reverse transcription‐polymerase chain reaction (RT‐PCR) assay, we investigated the pattern of Oct‐4 expression during mouse oocyte growth in females intraperitoneally injected with pregnant mare serum gonadotropin (PMSG) alone or PMSG followed by human chorionic gonadotropin (hCG). The results of this study show that gonadotropins induced two major increases in Oct‐4 expression during folliculogenesis: (1) 48 hr after PMSG injection, in oocytes isolated from primordial follicles; and (2) following a surge of hCG, in preovulatory antral oocytes. These results suggest a potential twofold role for this gene in the recruitment of oocytes for initiating growth and in the selection of oocytes for ovulation. Also, they may contribute to our knowledge of the molecular bases of oocyte growth, meiosis resumption, and acquisition of a developmental competence. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
The murine Dnali1 gene encodes a flagellar protein that interacts with the cytoplasmic dynein heavy chain 1
Authors: Rashid Sajid , Breckle Rolf , Hupe Mike , Geisler Stephanie , Doerwald Nadine , Neesen Juergen 
Published: February 2006

AbstractAxonemal dyneins are large motor protein complexes generating the force for the movement of eukaryotic cilia and flagella. Disruption of axonemal dynein function leads to loss of ciliary motility and can result in male infertility or lateralization defects. Here, we report the molecular analysis of a murine gene encoding the dynein axonemal light intermediate chain Dnali1. The Dnali1 gene is localized on chromosome 4 and consists of six exons. It is predominantly expressed within the testis but at a lower level Dnali1 transcripts were also observed in different murine tissues, which exhibit cilia. Two transcript variants were detected, generated by the usage of two alternative polyadenylation signals within exon 6. Antibodies were raised against a GST–Dnali1 fusion protein and used to localize Dnali1 within differentiating male germ cells. Dnali1 is strongly expressed in spermatids but was also detected in spermatocytes. Moreover, the Dnali1 protein was localized in cilia of the trachea as well as in flagella of mature sperm supporting its function as an axonemal dynein. To identify putative Dnali1 interacting polypeptides, a yeast two‐hybrid approach was performed using a murine testicular cDNA library. By this assay, the C‐terminal part of the cytoplasmic dynein heavy chain 1 was identified as a putative interacting polypeptide of Dnali1. The interaction between the axonemal and the cytoplasmic dynein fragments was proven by co‐immuno and co‐localization experiments. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Quantifying exchange rates in chemical exchange saturation transfer agents using the saturation time and saturation power dependencies of the magnetization transfer effect on the magnetic resonance imaging signal (QUEST and QUESP): Ph calibration for poly‐L‐lysine and a starburst dendrimer
Authors: McMahon Michael T. , Gilad Assaf A. , Zhou Jinyuan , Sun Phillip Z. , Bulte Jeff W. M. , van Zijl Peter C. M. 
Published: February 2006

AbstractThe ability to measure proton exchange rates in tissue using MRI would be very useful for quantitative assessment of magnetization transfer properties, both in conventional MT imaging and in the more recent chemical exchange saturation transfer (CEST) approach. CEST is a new MR contrast mechanism that depends on several factors, including the exchange rate of labile protons in the agent in a pH‐dependent manner. Two new methods to monitor local exchange rate based on CEST are introduced. The two MRI‐compatible approaches to measure exchange are quantifying exchange using saturation time (QUEST) dependence and quantifying exchange using saturation power (QUESP) dependence. These techniques were applied to poly‐L‐lysine (PLL) and a generation‐5 polyamidoamine dendrimer (SPD‐5) to measure the pH dependence of amide proton exchange rates in the physiologic range. Data were fit both to an analytical expression and to numerical solutions to the Bloch equations. Results were validated by comparison with exchange rates determined by two established spectroscopic methods. The exchange rates determined using the four methods were pooled for the pH‐calibration curve of the agents consisting of contributions from spontaneous (k0) acid catalyzed (ka), and base catalyzed (kb) exchange rate constants. These constants were k0 = 68.9 Hz, ka = 1.21 Hz, kb = 1.92 × 109 Hz, and k0 = 106.4 Hz, ka = 25.8 Hz, kb = 5.45 × 108 Hz for PLL and SPD‐5, respectively, showing the expected predominance of base‐catalyzed exchange for these amide protons. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Hepatic lipid accumulation in healthy subjects: A comparative study using spectral fat‐selective MRI and volume‐localized 1H‐MR spectroscopy
Authors: Machann Jürgen , Thamer Claus , Schnoedt Birgit , Stefan Norbert , Haring Hans‐Ulrich , Claussen Claus D. , Fritsche Andreas , Schick Fritz 
Published: February 2006

AbstractFat‐selective MRI was applied to assess the amount and spatial distribution of hepatic lipids (HL) in healthy subjects. The results were compared with those obtained by localized 1H‐MR spectroscopy (MRS). Ninety subjects (23–63 years old) underwent single‐slice fat‐selective MRI with spatial‐spectral excitation and volume‐localized spectroscopy at 1.5 T. HLs were analyzed in ventral and dorsal regions of interest (ROIs) of the liver in fat‐selective images. Spectra were evaluated using the integral signal of methylene and methyl signals. The fat‐selective images showed smooth and homogeneous distribution of HL over the entire cross section of the liver. There was, however, a marked interindividual variability in the amount of HL. MRS revealed a lipid signal fraction between 0.5% and 39.3%. The fat content in the ROIs in images correlated well with the spectroscopic results (r ≥ 0.95). Both techniques provide sufficient sensitivity for a reliable and quantitative assessment of liver steatosis in subjects without liver disease. 1H‐MRS has a higher sensitivity compared to MRI, especially for small amounts of HL, which may be of interest for metabolic interventions. Fat‐selective images provide more spatial information about fat distribution, which makes this technique suitable for clinical imaging of patients with liver disease. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Novel 1H NMR approach to quantitative tissue oximetry using hexamethyldisiloxane
Authors: Kodibagkar Vikram D. , Cui Weina , Merritt Matthew E. , Mason Ralph P. 
Published: February 2006

Abstract19F NMR spin‐lattice relaxometry of hexafluorobenzene (HFB) has been shown to be a highly sensitive indicator of tumor oxygenation. In this study hexamethyldisiloxane (HMDSO) was identified as a proton NMR analog, and its potential as a probe for investigating dynamic changes in tissue oxygen tension (pO2) was evaluated. HMDSO has a single proton resonance (δ= –0.3 ppm) and the spin‐lattice relaxation rate, Rl (= 1/T1) exhibits a linear dependence on pO2: R1 (s–1) = 0.1126 + 0.0013* pO2 (torr) at 37°C. To demonstrate application in vivo, HMDSO was administered into healthy rat thigh muscle (100 μl) and tumors (50 μl). Local pO2 was determined by using pulse‐burst saturation recovery (PBSR) 1H NMR spectroscopy to assess R1. Water and fat signals were effectively suppressed by frequency‐selective excitation of the HMDSO resonance. Rat thigh muscle had a mean baseline pO2 of 35 ± 11 torr, with a typical stability of ±3 torr over 20 min, when the rats breathed air. Altering the inhaled gas to oxygen produced a significant increase in pO2 to 100–200 torr. In tumors, altering the inspired gas also produced significant (albeit generally smaller) changes. This new pO2 reporter molecule offers a potentially valuable new tool for investigating pO2 in vivo. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Contrast‐enhanced MRI of brown adipose tissue after pharmacological stimulation
Authors: Sbarbati Andrea , Cavallini Isabella , Marzola Pasquina , Nicolato Elena , Osculati Francesco 
Published: February 2006

AbstractA non‐invasive method for studying the modifications induced in lipid depots by hormonal stimulation could extend knowledge of adipose tissues. We studied the effect of adrenergic stimulation on interscapular brown adipose tissue (IBAT) of rats using contrast‐enhanced MRI. Controls and rats pre‐treated with adrenaline 40 s before the acquisition of pre‐contrast images were used. In the control group, IBAT showed an enhancement of 56 ± 29%, whereas adrenaline pre‐treatment resulted in a significantly higher value (83 ± 49%, P < 0.05). In the control group, the skeletal muscle of the anterior limb showed an enhancement of 24 ± 12%, while adrenaline pre‐treatment led to a higher value (26 ± 10%), although the difference was not significant. In the control group, the skeletal muscle adjacent to the IBAT showed an enhancement of 30 ± 13%, while adrenaline pre‐treatment resulted in a non‐significantly higher value (33 ± 10%). In both groups, enhancement values in the muscle adjacent to the IBAT were significantly higher than the values in the muscle of the anterior limb (P < 0.05). This study demonstrates the feasibility of detecting the effect of hormonal stimulation on small fat depots. The demonstration of greater blood flow in the muscles surrounding the IBAT than in the muscles of the anterior limb suggests that the muscles of the back operate in synergy with the IBAT. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.