bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular hydrogen elimination from 2,5‐dihydrofuran, 2,3‐dihydrofuran, and 2‐methyl‐2,5‐dihydrofuran: Quantum chemical and kinetics calculations
Authors: Dubnikova Faina , Lifshitz Assa 
Published: August 2002

AbstractDensity Function Theory calculations were carried out to evaluate the potential energy surfaces of H2 elimination from 2,5‐dihydrofuran, 2,3‐dihydrofuran, and 2‐methyl‐2,5‐dihydrofuran. The structure and energetics of the reactants, products, and transition states on the surfaces for all the three systems were determined and unimolecular rate constants for the H2 elimination were calculated from transition state theory. The potential energy surfaces in 2,5‐dihydrofuran and 2‐methyl‐2,5‐dihydrofuran have each closed shell, 6‐center transition state. The transition state for H2 elimination from 2,3‐dihydrofuran proceeds via two different pathways, both have barriers that are considerably higher than the barriers for H2 elimination from 2,5‐dihydrofuran and 2‐methyl‐2,5‐dihydrofuran. One pathway proceeds via a 4‐center transition state and one through a carbene intermediate. In all the cases the transition state leads to the formation of a H2‐furan complex toward a complete separation to H2 and furan. The calculated rate constants for 2,5‐dihydrofuran and 2‐methyl‐2,5‐dihydrofuran are in excellent agreement with the experimental observations. Owing to the very high barriers, the process in 2,3‐dihydrofuran cannot compete with other reaction channels, such as isomerizations, and cannot be observed experimentally. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 685–697, 2001
Dealing with soil variability: some insights from land degradation research in central Spain
Authors: Fitzjohn C. , Ternan J. L. , Williams A. G. , Perez‐Gonzalez A. , de Alba S. 
Published: August 2002

AbstractSoil variability is often seen as problematic in land degradation studies in terms of sampling effort, data interpretation and for the extrapolation of results to other areas or time periods. Examples are given from land degradation research undertaken in central Spain which demonstrate some of these problems associated with soil variability. Geostatistics is presented as a useful tool for quantifying soil variability and in particular the variogram for interpreting and understanding spatial patterns. Soil variability is also seen to complicate the issues surrounding management strategies and makes monospecific management strategies less likely to be successful. In recent years several studies have suggested that variability in soil properties and vegetation cover may reduce the risk of land degradation by minimizing the spatial extent of runoff and erosion. These studies suggest that increasing soil variability may prove to be an effective strategy for reducing the runoff and erosion risk. This paper discusses these ideas and highlights the importance of increasing thresholds above which runoff and erosion occurs for the success of such strategies. This in particular applies to many semiarid environments where thresholds are deemed to be extremely low. Finally, these concepts are placed in the context of scale where soil variability may be viewed as existing at a multitude of nested levels varying from the micro‐ to the macro‐scale. Copyright © 2002 John Wiley & Sons, Ltd.
Propylene glycol as a contrasting agent for optical coherence tomography to image gastrointestinal tissues
Authors: Wang Ruikang K. , Elder James B. 
Published: August 2002

AbstractBackground and ObjectiveOptical coherence tomography (OCT) is a recently developed imaging technique that has the potential to advance the early diagnosis of diseases in the human gastrointestinal (GI) tract. How ever, the high scattering nature of GI tissue limits its imaging depth and contrast. For more effective diagnosis using OCT, a concurrent improvement of imaging depth and contrast is, therefore, needed. In this work, we investigate the administration of chemical agents to the tissue as a means of improving the capability of OCT imaging of clinically relevant microstructures of the GI tract.Study Design/Materials and MethodsNormal human GI tissues, including stomach and oesophagus were obtained from patients in hospital, and were imaged with OCT within 0.5–2 hours of removal. Immediately after the first imaging of the specimens with OCT, about 0.5 ml of 80% propylene glycol solution was applied onto the tissue surface and the tissue allowed to absorb the chemical compounds for 20 minutes. Another image was then taken at the same position. The specimens were then embedded and stained in preparation for histologic evaluation. Co‐registration of the images obtained using OCT before and after the topical application of the propylene glycol solution, and standard histopathologic processing provided basis for comparison.ResultsMore detailed micro‐structures, including the basal layer position and the cellular composition of the mucosal layer of GI tract tissues were observed after the topical application of propylene glycol solution, while these structures were not resolvable in the conventional OCT images.ConclusionsPropylene glycol could be used as a contrasting agent for OCT imaging of human GI tract tissues, allowing an increased capability of OCT for rapid clinical diagnosis in vivo. Lasers Surg. Med. 30:201‐208, 2002. © 2002 Wiley‐Liss, Inc.
Epigenetic silencing of PEG3 gene expression in human glioma cell lines*
Authors: Maegawa Shinji , Yoshioka Hirotaka , Itaba Noriko , Kubota Norika , Nishihara Shigeki , Shirayoshi Yasuaki , Nanba Eiji , Oshimura Mitsuo 
Published: August 2002

AbstractGenomic imprinting, the phenomenon in which alleles of genes are expressed differentially depending on their parental origins, has important consequences for mammalian development, and disturbance of normal imprinting leads to abnormal embryogenesis and some inherited diseases and is also associated with various cancers. In the context of screening for novel imprinted genes on human chromosome 19q13.4 with mouse A9 hybrids, we identified a maternal allele–specific methylated CpG island in exon 1 of paternally expressed imprinted gene 3 (PEG3), a gene that exhibits paternal allele–specific expression. Because PEG3 expression is downregulated in some gliomas and glioma cell lines, despite high‐level expression in normal brain tissues, we investigated whether the loss of PEG3 expression is related to epigenetic modifications involving DNA methylation. We found monoallelic expression of PEG3 in all normal brain tissues examined and five of nine glioma cell lines that had both unmethylated and methylated alleles; the remaining four glioma cell lines exhibited gain of imprinting with hypermethylated alleles. In addition, treatment of glioma cell lines with the DNA demethylating agent 5‐aza‐2′‐deoxycytidine reversed the silencing of PEG3 biallelically. In this article, we report that the epigenetic silencing of PEG3 expression in glioma cell lines depends on aberrant DNA methylation of an exonic CpG island, suggesting that PEG3 contributes to glioma carcinogenesis in certain cases. © 2001 Wiley‐Liss, Inc.
Regulation of cellular invasion and matrix metalloproteinase activity in HepG2 cell by connexin 26 transfection
Authors: Yano Tomohiro , Yamasaki Hiroshi 
Published: August 2002

AbstractWe previously reported that connexin (Cx) 26 expression is involved in negative growth control of HepG2 cells established from a human hepatoma. We also found that induction of E‐cadherin and subsequent formation of a cell adhesion complex were induced in HepG2 cells by C × 26 expression. To examine the exact role of C × 26‐induced E‐cadherin junctions in regulating appearance of malignant phenotypes of HepG2 cells, we expressed a C × 26 antisense oligodeoxynucleotide (AS‐ODN) in an established HepG2 cell clone that has stable expression of C × 26 genes. We investigated changes in the expression of E‐cadherin, the localization of β‐catenin, and some malignant phenotypes of HepG2 clone after the suppression of C × 26 expression by AS‐ODN treatment. The AS‐ODN treatment prevented the expression of C × 26 and E‐cadherin, and the localization of β‐catenin was changed from cytoplasmic membrane to the cytoplasm. In parallel, a morphological change from a monolayer of polygonal cells to multilayered colonies was induced by the treatment, indicating a change of a malignant phenotype of HepG2 cells. The activity of matrix metalloproteinase 9 (MMP‐9) was elevated by the AS‐ODN treatment. A concomitant increase in invasiveness of the C × 26‐expressing cells by the treatment was also observed in an in vitro assay with Matrigel matrix. These results suggest that the induction of E‐cadherin and formation of the cell adhesion complex by C × 26 expression contribute to the reversal of some malignant phenotypes of HepG2 cells. Furthermore, the C × 26‐dependent expression of E‐cadherin leads to reduction of the invasiveness of the cells through suppression of MMP‐9 activity. © 2001 Wiley‐Liss, Inc.
Frequent loss of imprinting of IGF2 and MEST in lung adenocarcinoma
Authors: Kohda Masakazu , Hoshiya Hidetoshi , Katoh Motonobu , Tanaka Isao , Masuda Ryo , Takemura Tamiko , Fujiwara Mutsunori , Oshimura Mitsuo 
Published: August 2002

AbstractGenomic imprinting is a parental origin–specific chromosomal modification that causes differential expression of maternal and paternal alleles of a gene. Accumulating evidence suggests that deregulation of imprinted genes, including loss of imprinting (LOI), plays a role in oncogenesis. In the present study, we investigated allelic expression of six imprinted genes in human lung adenocarcinomas as well as in matched normal lung tissue. Informative cases showing heterozygosity for the gene of interest were selected from 35 patients. LOI of the insulin‐like growth factor 2 gene (IGF2) and mesoderm‐specific transcript (MEST, also known as paternally expressed gene 1) was noted in 47% (seven of 15) and 85% (11 of 13) of informative cases, respectively. Monoallelic expression was maintained in all the matched normal tissues examined. LOI of IGF2 was seen more frequently in moderately to poorly differentiated adenocarcinomas. In contrast, H19, small nuclear ribonucleoprotein–associated polypeptide N gene (SNRPN), necdin gene (NDN), and long QT intronic transcript 1 (LIT1) exhibited consistent monoallelic expression in all the informative samples. These findings indicated that independent deregulation took place in imprinted genes and suggested that aberrant imprinting of IGF2 and MEST was involved in the development of lung adenocarcinoma. © 2001 Wiley‐Liss, Inc.
Vertical externality and strategic delegation
Authors: Park Eun‐Soo 
Published: August 2002

AbstractThis paper examines the effects of vertical externality generated by the upstream monopoly on the incentives that owners of competing downstream firms give their managers. It is shown that the introduction of the upstream monopoly may have significant effects on the incentive schemes for the downstream firms' managers. In particular, it is shown that in equilibrium, each owner obtains the simple Nash equilibrium outcome regardless of the mode of competition (quantity or price) in the downstream market. Copyright © 2002 John Wiley & Sons, Ltd.
Dopa‐responsive parkinsonism secondary to right temporal lobe haemorrahage
Authors: Ling Monica J. , Aggarwal Arun , Morris John G.L. 
Published: August 2002

AbstractA 46‐year‐old man developed a symmetrical parkinsonian syndrome 7 weeks after large right temporal intracerebral haemorrhage resulting from a ruptured arteriovenous malformation. His signs included bradykinesia, rigidity, start hesitation, and poor postural reflexes, without a resting tremor. He also had signs of a Parinaud's syndrome. Computed tomography and magnetic resonance imaging of the brain demonstrated changes in the right temporal lobe associated with the haemorrhage but no abnormality of the basal ganglia or midbrain. Levodopa therapy produced a dramatic improvement within a few days of commencement. We postulate that the parkinsonism resulted from midbrain compression secondary to transtentorial herniation. Although parkinsonism is a rare complication of lobar intracerebral haemorrhage, it is important to recognise as it may be potentially treatable. © 2002 Movemement Disorder Society.
Complex movement disorders following bilateral paramedian thalamic and bilateral cerebellar infarcts
Authors: Tan E.K. , Chan L.‐L. , Auchus A.P. 
Published: August 2002

AbstractComplex movement disorders (CMD; including tremor, dystonias, choreoatheosis, and myoclonus) following infarcts in the posterior and posterolateral thalamic nuclei have been reported. This case of a 59‐year‐old man who developed CMD following bilateral paramedian and bilateral cerebellar infarcts illustrates the lack of anatomic specificity and the diverse pathophysiology which may underlie CMD. © 2001 Movement Disorder Society.
Observability and stabilization of the vibrating string equipped with bouncing point sensors and actuators
Authors: Khapalov A. Y. 
Published: August 2002

AbstractThe issues of observability and stabilization are analysed for a vibrating string equipped, respectively, either with a point sensor measuring its displacement or a vertical tie‐down viscous damper. It is well known that the aforementioned properties hold for the stationary devices of these types only when they are placed at the ‘irrational points’ of the string. The latter creates obvious difficulties in applications. In this article we discuss how mobile point sensors and dampers, bouncing in a rather simple fashion between any two points on the string, can be employed instead in a more ‘feasible and robust’ way. Copyright © 2001 John Wiley & Sons, Ltd.
Mathematical analysis of some new Reynolds‐rod elastohydrodynamic models
Authors: Bayada G. , Cid B. , Vázquez C. 
Published: August 2002

AbstractIn this paper, some new elastohydrodynamic Reynolds‐rod models are posed to obtain the existence of solution (the lubricant pressure and the elastic rod displacement). More precisely, a sign restriction on fluid pressure for cavitation modelling and different unilateral conditions on the rod displacement associated with a rigid structure coating are formulated in terms of coupled variational inequalities. The particular hinged or clamped boundary conditions on the rod displacement require different techniques to prove the existence of solution. Besides nearly linear coupled problems, two non‐linear rod problems including curvature effects are analysed. Mainly, regularity results and L∞ estimates for the solution of variational inequalities and fixed‐point theorems lead to the existence results for the various coupled models. Copyright © 2001 John Wiley & Sons, Ltd.
Infinitely many stationary solutions for a simple climate model via a shooting method
Authors: Díaz J. I. , Tello L. 
Published: August 2002

AbstractIn this paper, we study the number of steady solutions of a non‐linear model arising in Climatology. By applying a shooting method we show the existence of infinitely many steady solutions for some values of a parameter (the solar constant). This method allows us to determine how many times a solution attains the critical temperature (−10°C) at which the coalbedo is assumed to be discontinuous. Copyright © 2002 John Wiley & Sons, Ltd.
A combination of time‐domain versions of PO and PTD with the FDTD method to evaluate human exposure to an electromagnetic field in an urban environment
Authors: Nonídez L. , Martínez‐Búrdalo M. , Martín A. , Villar R. 
Published: August 2002

AbstractIn this work, a combination of the physical optics in the time domain (TDPO) method and a time‐domain version of the equivalent currents of the physical theory of diffraction (TDPTD) with the finite‐difference time‐domain method (FDTD) is presented in order to compute scattered fields by flat plates. The technique is applied for calculating the energy absorbed by a human head exposed to an electromagnetic field in the presence of a reflecting wall. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 371–374, 2001.
Microwave holographic 3‐D rendering system using a reduced‐size planar array antenna
Authors: Elsadek Hala , Eldeeb Hesham , De‐Flaviis Franco , Jofre Luis , Abdallah Esmat , Hashish Essam 
Published: August 2002

AbstractA compact rendering system for establishing a three‐dimensional (3‐D) pointer is possible by combining microwave holography with microstrip antenna arrays to enter 3‐D coordinates of a point in space into computer memory. To obtain the reduction in system size, new solutions are proposed in both the holographic reconstruction algorithms and the receiving planar array antenna. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 397–402, 2001.
Green's functions in a PC–PPWG structure
Authors: Caloz Christophe 
Published: August 2002

AbstractThe phased‐array method (PAM), recently introduced to compute Green's functions in infinite photonic crystals (PCs), is extended to the problem of a parallel‐plate waveguide (PPWG) structure loaded by a 2‐D PC. Numerical results show that the final Green's function exhibits a standing‐wave behavior and a high confinement of energy near the source, which emphasize the filtering effect of the photonic bandgap (PBG). Other characteristics of the Green's function are also discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 405–408, 2001.
Resonant contrawound toroidal helix antenna
Authors: Hansen R. C. 
Published: August 2002

AbstractThe resonant CWTHA is examined via a moment‐method simulation. The results show a very high impedance at first resonance with a narrow bandwidth and low efficiency. At second resonance, the resistance is less than an ohm, the reactance is zero, and again, the bandwidth is narrow. The azimuth patterns are not omnidirectional, but may have a dip of 10 dB or more. The simulation shows a loop‐mode cancellation of at least 140 dB. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 408–410, 2001.
A compact dual‐band microstrip patch antenna suitable for DCS/GPS operations
Authors: Wu Jian‐Yi , Row Jeen‐Sheen , Wong Kin‐Lu 
Published: August 2002

AbstractA new integrated structure of a two‐element microstrip patch antenna with two feeds for DCS/GPS dual‐band operations is proposed. The radiating element for DCS (1710–1880 MHz) operation is a broadband low‐profile cylindrical monopole top loaded with a shorted square patch, which gives a linearly polarized conical‐pattern radiation. The second radiating element is a square‐ring microstrip patch with truncated corners for GPS operation at 1575 GHz, which provides circularly polarized broadside radiation patterns. The two radiating elements are integrated in the proposed antenna to have a compact structure. The proposed antenna meets the bandwidth requirements of DCS and GPS systems, and is suitable for mounting on a vehicle. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 410–412,
Band‐selective extraction of resonant frequencies in high‐Q resonators
Authors: Haala Jens , Zhang Ying , von Hagen Jürgen , Wiesbeck Werner 
Published: August 2002

AbstractThe efficient computation of intrinsic frequencies of resonators is presented by an FDTD computation using a new excitation function and a subsequent application of Prony's method. For an accurate extraction of the frequencies, the excitation function must be rather short in the time domain, as well as having a well‐defined frequency content. A sinc‐type excitation function allows very short simulation times, as well as convenient computation near the Courant limit. The sampling of Prony's method starts after the excitation has decayed, a point in time well defined with the new excitation. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 438–441, 2001.
An integrated probe for phaseless plane‐polar near‐field measurements
Authors: Costanzo Sandra , Di Massa Giuseppe 
Published: August 2002

AbstractThe use of an integrated probe performing phaseless near‐field measurements on a plane‐polar scanning geometry is presented. A significant reduction in the acquisition time as well as in the size of the measurement facility is obtained. A uniformly spaced array of dipoles is chosen as test antenna to validate the proposed method. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 293–295, 2001.
J‐IMPEACH‐MBC: a new concatenated NMR experiment for F1 scalable, J‐resolved HMBC
Authors: Williamson R. Thomas , Marquez Brian L. , Gerwick William H. , Martin Gary E. , Krishnamurthy V. V. 
Published: August 2002

AbstractA new and improved NMR experiment for F1 scalable, J‐Resolved HMBC is presented. This experiment, called J‐IMPEACH‐MBC, utilizes a minimum number of 180° pulses to preserve maximum signal‐to‐noise ratio and provides a variable scaling factor (N) that can be used to scale the heteronuclear couplings in F1. It should prove to be useful for the determination of relative stereochemistry and other structural problems. In addition, a description of the advantages of the J‐IMPEACH‐MBC compared with the J‐Resolved HMBC‐2 is presented. The method is exemplified with strychnine. Copyright © 2001 John Wiley & Sons, Ltd.
Propeller rotation of aryl groups in triarylsilanes and triarylstannanes
Authors: Lambert Joseph B. , Lin Lijun 
Published: August 2002

AbstractRotation of aryl groups was studied in eight systems with the general structure Ar3MX by changes in lineshapes as a function of temperature. Steric constraints were varied at each of the structural components (Ar, M, X). The barrier to rotation decreased as the central atom was changed from carbon to silicon to tin. When the substituent X was large (allyl or Cl), buttressing by the meta methyls in duryl raised the barrier. For X = H, however, buttressing decreased the barrier. Copyright © 2001 John Wiley & Sons, Ltd.
Full term development of rabbit oocytes fertilized by Intracytoplasmic sperm injection&ast;
Authors: Deng Manqi , Yang Xiangzhong (Jerry) 
Published: August 2002

AbstractIntracytoplasmic sperm injection &lpar;ICSI&rpar; has been applied successfully in the treatment of male infertility in humans and in fertilization research in mice. However, the technique has had limited success in producing offspring in other species including the rabbit. The aim of this research was to test the in vitro and in vivo developmental of rabbit oocytes after ICSI. Sperm used for ICSI were collected from mature Dutch Belted buck and washed 2&ndash;3 times with PBS&thinsp;&plus;&thinsp;0.1&percnt; polyvinyl alcohol &lpar;PVA&rpar; and then mixed with 10&percnt; polyvinyl pyrrolidone &lpar;PVP&rpar; prior to microinjection. Oocytes were collected from superovulated does 14&ndash;15 hr after hCG injection and were fertilized by microinjection of a single sperm into the ooplasm of each oocyte without additional activation treatment. After ICSI, the presumed zygotes were either cultured in KSOM&thinsp;&plus;&thinsp;0.3&percnt; BSA for 4 days or transferred into oviducts of recipient does at the pronuclear or 2&hyphen;cell stage. A high percentage of fertilization &lpar;78&percnt;, n&thinsp;&equals;&thinsp;114&rpar; and blastocyst development &lpar;39&percnt;&rpar; was obtained after ICSI. Control oocytes, receiving a sham injection, exhibited a lower activation rate &lpar;31&percnt;, n&thinsp;&equals;&thinsp;51&rpar; and were unable to develop to the blastocyst stage, suggesting that the blastocysts developed following ICSI were derived from successful fertilization rather than parthenogenetic development. A total of 113 embryos were transferred to six recipient does. Two recipients became pregnant and delivered seven live young. Our results demonstrated that rabbit oocytes can be successfully fertilized and activated by ICSI and can result in the birth of live offspring. Mol. Reprod. Dev. 59:38&ndash;43, 2001. &copy; 2001 Wiley&hyphen;Liss, Inc.