bluuebunny/crossref_metadata_2025 huggingface dataset:
Meta‐analysis: effect of hepatitis C virus infection on mortality in dialysis
Authors: Fabrizi F. , Martin P. , Dixit V. , Bunnapradist S. , Dulai G.
Published: December 2004

Background: The natural history of hepatitis C virus infection among patients on long‐term dialysis treatment remains incompletely understood. Efforts to elucidate the natural history of hepatitis C virus in this population are difficult because of the slowly progressive nature of hepatitis C virus with often an unrecognized onset in patients whose life‐expectancy is substantially diminished by end‐stage renal disease.

Aim: To conduct a systematic review of the published medical literature concerning the impact of hepatitis C virus infection on the survival of patients receiving chronic dialysis. The relative risk of mortality was regarded as the most reliable outcome end‐point.

Methods: We used the random effects model of DerSimonian and Laird to generate a summary estimate of the relative risk for mortality with hepatitis C virus across the published studies.

Results: We identified four clinical trials (2341 unique patients); three (75%) of them were prospective, cohort studies; the fourth was a case–control study. Pooling of study results demonstrated that presence of antihepatitis C virus antibody was an independent and significant risk factor for death in patients on maintenance dialysis. The summary estimate for relative risk was 1.57 with a 95% confidence interval (CI) of 1.33–1.86. A test for homogeneity of the relative risks across the four studies gave aP‐value of 0.77. As a cause of death, hepatocellular carcinoma and liver cirrhosis were significantly more frequent among antihepatitis C virus‐positive than ‐negative dialysis patients.

Conclusions: This meta‐analysis demonstrates that antihepatitis C virus‐positive patients on dialysis have an increased risk of mortality compared with hepatitis C virus‐negative patients. The excess risk of death in hepatitis C virus‐positive patients may be at least partially attributed to chronic liver disease with its attendant complications. Clinical trials with extended follow‐up are currently under way to assess the effect of hepatitis C virus treatment on the excess risk of mortality in this population.
Formation of polar‐body‐like structures induced in polyspermic starfish oocytes that had been inseminated at the germinal vesicle stage
Authors: Tei Jinsei , Kani Satomi , Hanai Kuninari , Miyaguchi Tohru , Yamamoto Kenya
Published: December 2004

Immature starfish oocytes, which are arrested at the first meiotic prophase and contain a large nucleus called the germinal vesicle (GV), are known to accept multiple sperm on insemination. We found that if these polyspermic starfish oocytes are induced to mature, they often form small protrusion(s) adjacent to the first polar body emitted shortly earlier. We refer to these protrusion(s) as ‘polar‐body‐like structures (PLS).’ Fluorescent staining of PLS indicated that they were not merely cytoplasmic protrusions, but contained some chromatin. Maturing process of these polyspermic oocytes was examined by immnofluorescent staining, which showed that: (i) numerous sperm asters were observed after the onset of GV breakdown; (ii) before the first polar body (PB1) emission, a complex microtubular structure resembling a multipolar spindle was formed; and (iii) several isolated asters were observed after PB1 emission. These results indicate that PLS formation may be induced by interaction of meiosis‐I spindle with paternal centrosomes incorporated at GV stage.
Short‐Term Efficacy of a Telephone Intervention by Expert Nurses After An Implantable Cardioverter Defibrillator
Authors: DOUGHERTY CYNTHIA M. , LEWIS FRANCES MARCUS , THOMPSON ELAINE ADAMS , BAER JUSTIN D. , KIM WOOKSOO
Published: December 2004

The ICD is a common therapy for treatment of ventricular arrhythmias and prevention of sudden cardiac death. After ICD therapy, 50% of survivors are known to have significantly elevated anxiety, depression, anger, and fear in getting back to normal physical activities. Despite these problems, few interventions to improve adjustment have been rigorously evaluated within a clinical trial format. This article reports the short‐term efficacy of a structured weekly educational telephone intervention (8 weeks) delivered by expert cardiovascular nurses to recipients of an ICD. To test these effects, a two‐group (n = 84/group) randomized clinical trial design was used with measures at baseline (hospital discharge), 1 month, and 3 months after ICD therapy. The study sample were first time ICD recipients for secondary prevention of sudden cardiac arrest. Primary outcomes included (1) physical functioning (Patient Concerns Assessment [PCA], Short‐Form Health Survey [SF‐12], ICD shocks), (2) psychological adjustment (State‐Trait Anxiety Inventory [STAI]), Centers for Epidemiologic Studies‐Depression (CES‐D), (3) knowledge (Sudden Cardiac Arrest [SCA] knowledge assessment), and (4) health care use (emergency room visits, outpatient visits, hospitalizations). The intervention group, as compared to the control group, significantly reduced mean PCA symptoms at 1 month (11.3–8.8 vs 9.7–9.3, respectively, P < 0.02), and reduced state anxiety (36.1–31.9 vs 33.1–33.0, respectively, P < 0.08), and enhanced knowledge (21.8–22.4 vs 21.4–21.7, respectively, P < 0.02) at 3 months. The intervention did not significantly impact short‐term health care use. A structured telephone intervention delivered during the first 8 weeks after ICD therapy by expert cardiovascular nurses decreased ICD related physical symptoms and anxiety, and increased SCA knowledge over 3 months.
Langmuir Supercells: A Mechanism for Sediment Resuspension and Transport in Shallow Seas
Authors: Gargett A. , Wells J. , Tejada-Martínez A. E. , Grosch C. E.
Published: December 2004

Recent measurements at a cabled sea-floor node in 15 meters of water off the coast of New Jersey suggest that Langmuir supercells, Langmuir circulations that achieve vertical scales equal to the water depth under extended storms, are an important mechanism for major sediment resuspension events on the extensive shallow shelves off the eastern U.S. coast. Because sediment resuspension is a prelude to transport, supercell events are a necessary condition for major sediment transport. Such events may also contribute to shelf-sea exchange and to offshore gradation of benthic community structure in shallow seas.
A Draft Sequence for the Genome of the Domesticated Silkworm (
Bombyx mori
)
Authors:   Biology analysis group, Xia Qingyou , Zhou Zeyang , Lu Cheng , Cheng Daojun , Dai Fangyin , Li Bin , Zhao Ping , Zha Xingfu , Cheng Tingcai , Chai Chunli , Pan Guoqing , Xu Jinshan , Liu Chun , Lin Ying , Qian Jifeng , Hou Yong , Wu Zhengli , Li Guanrong , Pan Minhui , Li Chunfeng , Shen Yihong , Lan Xiqian , Yuan Lianwei , Li Tian , Xu Hanfu , Yang Guangwei , Wan Yongji , Zhu Yong , Yu Maode , Shen Weide , Wu Dayang , Xiang Zhonghuai ,   Genome analysis group, Yu Jun , Wang Jun , Li Ruiqiang , Shi Jianping , Li Heng , Li Guangyuan , Su Jianning , Wang Xiaoling , Li Guoqing , Zhang Zengjin , Wu Qingfa , Li Jun , Zhang Qingpeng , Wei Ning , Xu Jianzhe , Sun Haibo , Dong Le , Liu Dongyuan , Zhao Shengli , Zhao Xiaolan , Meng Qingshun , Lan Fengdi , Huang Xiangang , Li Yuanzhe , Fang Lin , Li Changfeng , Li Dawei , Sun Yongqiao , Zhang Zhenpeng , Yang Zheng , Huang Yanqing , Xi Yan , Qi Qiuhui , He Dandan , Huang Haiyan , Zhang Xiaowei , Wang Zhiqiang , Li Wenjie , Cao Yuzhu , Yu Yingpu , Yu Hong , Li Jinhong , Ye Jiehua , Chen Huan , Zhou Yan , Liu Bin , Wang Jing , Ye Jia , Ji Hai , Li Shengting , Ni Peixiang , Zhang Jianguo , Zhang Yong , Zheng Hongkun , Mao Bingyu , Wang Wen , Ye Chen , Li Songgang , Wang Jian , Wong Gane Ka-Shu , Yang Huanming
Published: December 2004

We report a draft sequence for the genome of the domesticated silkworm (
Bombyx mori
), covering 90.9% of all known silkworm genes. Our estimated gene count is 18,510, which exceeds the 13,379 genes reported for
Drosophila melanogaster
. Comparative analyses to fruitfly, mosquito, spider, and butterfly reveal both similarities and differences in gene content.
Lymphotoxin-Mediated Regulation of γδ Cell Differentiation by αß T Cell Progenitors
Authors: Silva-Santos Bruno , Pennington Daniel J. , Hayday Adrian C.
Published: December 2004

The thymus gives rise to two T cell lineages, αβ and γδ, that are thought to develop independently of one another. Hence, double positive (DP) thymocytes expressing CD4 and CD8 coreceptors are usually viewed simply as progenitors of CD4
+
and CD8
+
αβ T cells. Instead we report that DP cells regulate the differentiation of early thymocyte progenitors and γδ cells, by a mechanism dependent on the transcription factor RORgt, and the lymphotoxin (LT) β receptor (LTβR). This finding provokes a revised view of the thymus, in which lymphoid tissue induction-type processes coordinate the developmental and functional integration of the two T cell lineages.
Superconductivity Modulated by Quantum Size Effects
Authors: Guo Yang , Zhang Yan-Feng , Bao Xin-Yu , Han Tie-Zhu , Tang Zhe , Zhang Li-Xin , Zhu Wen-Guang , Wang E. G. , Niu Qian , Qiu Z. Q. , Jia Jin-Feng , Zhao Zhong-Xian , Xue Qi-Kun
Published: December 2004

We have fabricated ultrathin lead films on silicon substrates with atomic-scale control of the thickness over a macroscopic area. We observed oscillatory behavior of the superconducting transition temperature when the film thickness was increased by one atomic layer at a time. This oscillating behavior was shown to be a manifestation of the Fabry-Pérot interference modes of electron de Broglie waves (quantum well states) in the films, which modulate the electron density of states near the Fermi level and the electron-phonon coupling, which are the two factors that control superconductivity transitions. This result suggests the possibility of modifying superconductivity and other physical properties of a thin film by exploiting well-controlled and thickness-dependent quantum size effects.
A Diarylquinoline Drug Active on the ATP Synthase of
Mycobacterium tuberculosis
Authors: Andries Koen , Verhasselt Peter , Guillemont Jerome , Göhlmann Hinrich W. H. , Neefs Jean-Marc , Winkler Hans , Van Gestel Jef , Timmerman Philip , Zhu Min , Lee Ennis , Williams Peter , de Chaffoy Didier , Huitric Emma , Hoffner Sven , Cambau Emmanuelle , Truffot-Pernot Chantal , Lounis Nacer , Jarlier Vincent
Published: December 2004

The incidence of tuberculosis has been increasing substantially on a worldwide basis over the past decade, but no tuberculosis-specific drugs have been discovered in 40 years. We identified a diarylquinoline, R207910, that potently inhibits both drug-sensitive and drug-resistant
Mycobacterium tuberculosis
in vitro (minimum inhibitory concentration 0.06 μg/ml). In mice, R207910 exceeded the bactericidal activities of isoniazid and rifampin by at least 1 log unit. Substitution of drugs included in the World Health Organization's first-line tuberculosis treatment regimen (rifampin, isoniazid, and pyrazinamide) with R207910 accelerated bactericidal activity, leading to complete culture conversion after 2 months of treatment in some combinations. A single dose of R207910 inhibited mycobacterial growth for 1 week. Plasma levels associated with efficacy in mice were well tolerated in healthy human volunteers. Mutants selected in vitro suggest that the drug targets the proton pump of adenosine triphosphate (ATP) synthase.
New insights about the hostguest chemistry of the tungsten oxo complex of calix[4]arene, and novel "one pot" difunctionalizations of calix[4]arene using tetrachlorometal(VI) oxide (M = Mo, W)
Authors: Mongrain Pascal , Douville Jasmin , Gagnon Jonathan , Drouin Marc , Decken Andreas , Fortin Daniel , Harvey Pierre D
Published: December 2004

The strong Lewis acid tungsten oxo complex of calix[4]arene can be obtained in both hydrated and non-hydrated forms. This complex coordinates a water molecule inside the cavity via strong O···W interactions with relatively short distances of 2.284(4) and 2.329(2) Å for the tungsten oxo complex of calix[4]arene··H2O·aniline (1), and the tungsten oxo complex of calix[4]arene·H2O·toluene (2·toluene), respectively. The strong interactions are also deduced by the relatively high H2O elimination temperature observed by TGA and DSC (above 200 °C). The coordinated water molecule inside the calix[4]arene cavity is characterized by a strong IR absorption at 3616 cm1, and a narrow resonance at ~1.2 ppm (the chemical shifts of the uncoordinated water are 1.55 and 1.60 ppm in C6D6 and CDCl3, respectively). This water molecule gives rise to H-bonds with aniline in 1. The tungsten oxo complex of 5,11,17,23-tetrabromocalix[4]arene (4), also binds H2O as the characteristic signatures are observed. The successful removal of H2O in 2, is performed under mild conditions using bis(tetrahydrofuran)-uranyl nitrate as a competitive Lewis acid. When this reaction is performed in acetonitrile, butyronitrile or tert-butylnitrile, the corresponding tungsten oxo complexes of calix[4]arene·acetonitrile (3), ·butyronitrile (5), and ·tert-butylnitrile (6) are obtained. The use of uranyl as a H2O abstractor is unprecedented. The X-ray structure of 3 consists of a tungsten oxo complex of calix[4]arene coordinated by an acetonitrile molecule (d(W···N = 2.412(2) Å). The tetra-5,11,17,23-choromethyl-25,26,27,28-tetrahydroxycalix[4]arene reacts with M(O)Cl4 (M = Mo, W) in a 1:1 stoichiometry, via a tetra FriedelCrafts addition of benzene or toluene, followed by a lower-rim complexation of the metal oxide, to form "flower-shaped" calix[4]arenes. This "one pot" double functionalization is unprecedented.Key words: calix[4]arene, tungsten, molybdenum, X-ray, hostguest, FriedelCrafts, Lewis acid, uranyl, DSC, TGA.
Surface-enhanced Raman spectroscopy with a laser pointer light source and miniature spectrometer
Authors: Young Matthew A , Stuart Douglas A , Lyandres Olga , Glucksberg Matthew R , Van Duyne Richard P
Published: December 2004

The initial steps toward a miniature, field portable sensor based on surface-enhanced Raman spectroscopy (SERS) are presented. It is demonstrated that a low-cost miniaturized Raman system can be used in place of a larger, higher-cost conventional Raman system. This system was developed by sequentially replacing components of a laboratory scale Raman spectroscopy system with smaller, lower-cost, commercially available components. For example, a green laser pointer was used as the excitation source, a reflectance probe fiber-optic cable was used for laser delivery and collection, and a compact card-based spectrometer was used for dispersion and detection. Spectra, collected with the laser pointer Raman system, are presented of a resonant (Rhodamine 6G) and a non-resonant (trans-1,2-bis(4-pyridyl)ethylene) molecule as well as a self-assembled monolayer (1-decanethiol). Small, low-cost sensors are in demand for a variety of applications, and SERS is positioned to contribute significantly with its remarkable sensitivity and molecular specificity.Key words: Raman, SERS, fiber-optics, sensor.
New method of energymass dispersion applied to mass spectral data from positively charged water vapor clusters
Authors: Walrafen George E , Carlon Hugh R
Published: December 2004

A new method is presented by which energymass, volumemass, and enthalpymass dispersion curves may be determined for charged water vapor clusters. This method involves two closely spaced partial pressures at a fixed temperature. The method is exemplified by using mass spectral data from positively charged water vapor clusters (H+(H2O)M) where 6 ≤ M ≤ 45. A ΔGmass dispersion was also determined using the ΔHmass dispersion for comparison. ΔG displays an enormous minimum, which is of signal importance because it indicates that a size of maximum stability (SMS) exists. The SMS corresponds to M = 13 for pressures between 0.056 and 0.151 bar (1 bar = 100 kPa) at 373.15 K, and to M = 32±1 for pressures between 0.473 and 0.556 bar at 372.15 K. The free energy corresponding to M = 45 occurs far above that corresponding to the SMS. The resultant instability leads to condensation for pressures above 0.556 bar at 372.15 K.Key words: clusters, mass spectrometry, thermodynamics, water vapour.
A vibrational spectroscopic study of the thermal behavior of Re2(CO)10 on zeolite Y
Authors: Poissant Robert R , Huang Yining
Published: December 2004

This work describes the thermal decomposition of Re2(CO)10 in zeolite Y, which generates the zeolite-supported complex Re0(CO)3(O-Z)3, where (O-Z) represents a framework oxygen. The adsorption and thermal decomposition of Re2(CO)10 was performed on dehydrated and hydrated zeolite NaY. The conversion to Re0(CO)3(O-Z)3 was not significantly affected by the presence of water within the supercages as the supported complex formed at around 200 °C no matter what the initial water content of the zeolite was. However, when the zeolite sample was treated at ≥200 °C for long periods, the adsorbed H2O became involved in the reactivity, playing a role as an oxidant. The subcarbonyl complex Re0(CO)3(O-Z)3 was oxidized, generating isolated Re2O7 or HReO4, or a mixture of both, which was dispersed inside the zeolite host. This result suggests that thermal decomposition of Re2(CO)10 on a hydrated zeolite under mild conditions can be a convenient route for preparation of zeolite-supported Re2O7 catalysts. Re0(CO)3(O-Z)3 was also formed in siliceous zeolite Y (SiY) upon heating. But it quickly decomposes into metal Re at around 200 °C, suggesting that the tricarbonyl species is destabilized in the almost natural zeolite framework. The present study also shows that FT-Raman spectroscopy is a useful technique for monitoring the behavior of the metal carbonyl species in zeolitic hosts.Key words: Raman spectroscopy, zeolite Y, rhenium carbonyl, rhenium oxide.
Synthesis and transformations of 60-, 62-, and 64-electron Co4(CO)x(PNR2)2(x= 8, 9, 10) clusters
Authors: Sánchez-Nieves Javier , Sterenberg Brian T , Udachin Konstantin A , Carty Arthur J
Published: December 2004

A unique family of bis-(amino)phosphinidene Co4clusters with electron counts in the 6064 e regime is described. The 62-electron (5 CoCo) butterfly compound [Co4(CO)8(µ-CO){µ3-P(TMP)}2] (TMP = 2,2,6,6-tetramethyl piperidyl) (1a) is obtained via condensation of the bridged (amino)phosphinidene complex [Co2(CO)6{µ-P(TMP)}]. Further heating and removal of CO gives the 60-electron (6 CoCo) tetrahedral compound [Co4(CO)6(µ-CO)2{µ3-P(TMP)}2] (3a). The reaction of K[Co(CO)4] with PCl2(N-i-Pr2) gives the 64-electron (4 CoCo) square-planar derivative [Co4(CO)8(µ-CO)2(µ4-PN-i-Pr2)2] (2), which loses one carbonyl ligand to form the 62-electron (5 CoCo) butterfly compound [Co4(CO)8(µ-CO)(µ3-PN-i-Pr2)2] (1b). Complex 1b releases another carbonyl to form the 60-electron (6 CoCo) tetrahedral compound [Co4(CO)6(µ-CO)2(µ3-PN-i-Pr2)2] (3b). X-ray structural analyses of compounds 1a, 1b, 2, and 3a have been carried out. The reversibility of the CO elimination reactions and the structural rearrangements accompanying changes in electron count in this series are discussed.Key words: cobalt, cluster compounds, phosphinidene, skeletal rearrangement.
Comparaison des caractéristiques des gros chicots entre une sapinière primitive et une sapinière aménagée sur la péninsule gaspésienne, Québec
Authors: Roberge Jean-Michel , Desrochers André
Published: December 2004

Snags (i.e., dead standing trees), and more particularly those of larger dimensions, are recognized as playing a major role in the maintenance of forest biodiversity. This study aimed to describe the characteristics of large snags in a primeval balsam fir forest in the Gaspé Peninsula (Quebec) and to compare them with those of an adjacent area composed of mature second-growth balsam fir stands. For snags ≥20 cm in diameter at breast height (DBH), mean density reached 51 snags/ha in the primeval forest and 24 snags/ha in the managed forest. The distribution of snags among DBH classes was similar in both areas. However, well-decayed snags made up a larger proportion of the snags in the primeval forest than in the managed forest. The proportion of snags with evidence of woodpecker feeding was higher in the managed forest than in the primeval forest. To ensure temporal and spatial continuity of snags in different decay stages, some stands could be left untouched for several rotations, and single snags could be kept or created in logged areas.
Conversion of fuel moisture content values to ignition potential for integrated fire danger assessment
Authors: Chuvieco Emilio , Aguado Inmaculada , Dimitrakopoulos Alexandros P
Published: December 2004

Fuel moisture content (FMC) estimation is a critical part of any fire danger rating system, since fuel water status is determinant in fire ignition and fire propagation. However, FMC alone does not provide a comprehensive assessment of fire danger, since other factors related to fire ignition (lightning, human factors) or propagation (wind, slope) also need to be taken into account. The problem in integrating all these factors is finding a common scale of danger rating that will make it possible to derive synthetic indices. This paper reviews the importance of FMC in fire ignition and fire propagation, as well as the most common methods of estimating FMC values. A simple method to convert FMC values to danger ratings is proposed, based on computing ignition potential from thresholds of moisture of extinction adapted to each fuel. The method has been tested for the Madrid region (central Spain), where a fire danger assessment system has been built. All the variables related to fire danger were integrated into a dedicated geographic information system and information provided to fire managers through a web mapping server.
Automatic thresholding for digital hemispherical photography
Authors: Ishida Megumi
Published: December 2004

This paper proposes an automatic thresholding method for the discrimination of sky and canopy elements in color hemispherical photographs taken with a digital camera (Nikon Coolpix 950). The exposures for photography were principally determined on the basis of zenith luminance. DIFphoto, which is diffuse transmittance calculated from the hemispherical photographs, was related to DIFsensor, which is diffuse transmittance measured directly with a photosynthetic photon flux density sensor. First, the thresholds for calculation of DIFphoto were manually assessed in the photographs to obtain the best match with DIFsensor. At the lower pixel-value level in the pixel histograms from the photographs, L-shaped curves were always recognized, and the threshold occurred at the point with the maximum curvature. Second, an automatic thresholding algorithm, taking into account the position of the thresholds, was computerized. Third, the relationships between DIFphoto and DIFsensor were field-tested across a wide range of light conditions. The method was effective in a planted coniferous forest and a natural broad-leaved forest and under overcast, twilit, and sunny sky conditions. The coefficients of determination between DIFsensor and DIFphoto were greater than 0.99. However, DIFphoto taken with Auto-Exposure was overestimated under dense canopy.
Early growth of white spruce underplanted beneath spaced and unspaced aspen stands in northeastern British Columbia
Authors: Comeau Philip G , Filipescu Cosmin N , Kabzems Richard , DeLong Craig
Published: December 2004

We examined the growth of white spruce planted underneath a 33-year-old stand of trembling aspen following thinning and fertilization. Thinning the stand to 2000 stems·ha1 resulted in increased light reaching spruce seedlings and significant increases in height and diameter growth of seedlings over that observed in either the unspaced or 3000 stems·ha1 treatments. Fertilization (applied 3 years prior to planting) stimulated development of understory vegetation and did not benefit the planted spruce. While growth was improved by thinning, the benefits of the thinning treatment to establishment of white spruce appeared to be small, and amounted to increasing seedling height from 62 cm (unthinned) to 73 cm (thinned to 1000 or 2000 stems·ha1) at the end of 5 years. Results indicated that when stands are thinned for the purpose of accelerating growth rates of underplanted spruce, residual basal areas above 25 m2·ha1 should be retained to suppress growth of understory vegetation. Comparison of height at age 5 for seedlings planted under untended stands at Fort Nelson with three sites near Dawson Creek indicated no differences between locations, when height at the time of planting was included as a covariate.
NANOSCALE OPTICAL PATTERNING USING EVANESCENT FIELDS AND SURFACE PLASMONS
Authors: BLAIKIE RICHARD J. , ALKAISI MAAN M. , McNAB SHAREE J. , MELVILLE DAVID O. S.
Published: December 2004

Patterning with sub-diffraction-limited resolution has been demonstrated using a simple photolithography technique. Evanescent fields and surface plasmons are critical to the image formation, which is investigated here using computer simulations and experiments. A regime exists in which surface plasmons are resonantly excited, which we have named Evanescent Interferometric Lithography (EIL); period halving and reduced exposure times characterize this exposure mode. Two other exposure modes have been investigated in which surface plasmons on a planar metallic film beneath the mask are used to improve pattern formation. In the first, Planar Lens Lithography (PLL), a planar silver layer excited near its plasma frequency is used to form a projected near-field image. For a 40-nm thick silver layer, we predict that resolution down to 40 nm should be possible. However, the image is affected by the loss in the silver layer, the mask period, duty cycle and surrounding refractive index. Experimental verification of PLL is presented for 1-micron period structures imaged through 120 nm of silver. Finally, simulations are used to show that surface plasmons on an underlying silver layer can be used to improve process latitude and depth of field. We have named this mode Surface Plasmon Enhanced Contact Lithography (SPECL).
THERMAL STABILITY STUDY OF TANTALUM NITRIDE THIN FILMS BY SPECTROSCOPIC ELLIPSOMETRY
Authors: XIE H. , TAN B. H. , COLLIER P. A. , NG F. L.
Published: December 2004

Spectroscopic ellipsometry was successfully applied in the evaluation of the thermal stability of thin films in air by detecting the changes in film optical properties and thickness. Tantalum nitride ( Ta x N y) films with a nominal thickness of 30 nm were deposited on silicon wafer and annealed at different temperatures from 200°C to 700°C. Annealing-induced changes in thickness and optical properties of Ta x N y were detected and determined by spectroscopic ellipsometry. Different approaches were adopted in the modeling and analysis of spectroscopic ellipsometric data. The results are consistent with the findings from Fourier Transform Infrared Spectroscopy (FTIR).
SURFACE FORCES AND ADHESION BETWEEN ELECTROLYTIC COPPER CATHODE SURFACES AND MICROSPHERE SURFACES OF GLASS AND POLYSTYRENE IN AQUEOUS ELECTROLYTE SOLUTIONS
Authors: ACUÑA SERGIO M. , SANCHEZ MARIA A. , TOLEDO PEDRO G.
Published: December 2004

Surface forces and adhesion between electrolytic copper cathode surfaces and sphere surfaces of glass and polystyrene were measured with an atomic force microscope (AFM) in water and in aqueous medium containing 104, 10-3 and 10-2 M sodium chloride at ambient temperature. Two types of copper surfaces were considered, oxidized and just-polished. Copper surfaces are submicroscopically rough and so at "contact", a film of intervening fluid separates substrate from probe. At close proximity, the interaction of the copper surfaces with either of the two probes is repulsive and such that extending and retracting force curves are essentially hysteresis-free. At higher separations, extending force curves for any probe-substrate combination were markedly repulsive and DLVO type. The higher the electrolyte concentration, the lower the range of the repulsive force. The system polystyrene-polished substrate displayed contact jumps for the higher electrolyte concentrations considered here, thus suggesting true adhesion between the surfaces. Strong and extremely long-ranged adhesive behavior were measured for the interaction between glass probes and oxidized copper substrates in low salt concentration solutions; at the origin are submicroscopic bubbles or cavities trapped between the surfaces and stabilized by the chemical heterogeneity of the interacting surfaces. A long-ranged, although weak, attractive interaction between polystyrene probes and just-polished copper substrates in aqueous salt solution belongs to the interacting surfaces although the intensity and range seems enhanced by the formation of bubbles.
ROOM TEMPERATURE AND ELEVATED TEMPERATURE CHARACTERIZATION OF NANOCRYSTALLINE SnO2 SURFACES BY SCANNING TUNNELING MICROSCOPY AND SPECTROSCOPY
Authors: MAFFEÏS T. G. G. , OWEN G. T. , WILKS S. P. , MALAGÙ C. , MARTINELLI G. , KENNEDY M. K. , KRUIS F. E.
Published: December 2004

Semiconductor gas sensors based on nanocrystalline SnO 2 offer many advantages over current technologies for detecting reducing gases, such as low cost, long lifetime, and high selectivity and sensitivity. However, the local surface properties on the nanoscale of SnO 2 nanocrystals are not fully understood, which impedes the exploitation of the full potential of SnO 2 for gas sensing applications. In this paper, we present a scanning tunneling microscopy and spectroscopy (STM/STS) study of nanocrystalline SnO 2 at room temperature, and under standard sensing conditions at 120°C. STS data indicate that the electronic surface properties change with nanoparticle size, temperature and exposure to gas. The surface density of states in the band gap is shown to increase with temperature while CO exposures induce a large drop in the density of band gap states as the CO molecules react with chemisorbed oxygen species.
CROSS-SECTIONAL SCANNING TUNNELING MICROSCOPY OF BURIED HETEROSTRUCTURE LASERS
Authors: COBLEY R. J. , TENG K. S. , BROWN M. R. , MAFFEÏS T. G. G. , WILKS S. P.
Published: December 2004

A single-mode buried heterostructure laser has been imaged using Cross-Sectional Scanning Tunneling Microscopy (X-STM). The problem of positioning the tip on the restricted active region on the (110) face has been overcome using combined Scanning Electron Microscopy (SEM).

In order to understand the change in the STM scans when biased, particularly the physical change in surface step defects caused by commercial sample preparation, the experimental setup has been modified to allow the sample to be biased. A simpler double quantum well test structure has been biased and it has been demonstrated that it is possible to continue performing STM whilst the device is powered. The change in the relative contrast across the image has been shown to be unaffected by this external bias for the range scanned, as predicted by a fully-coupled Poison drift–diffusion model calculated using Fermi–Dirac statistics.
ADHESION BETWEEN AN AFM PROBE AND AN INCOMPRESSIBLE ELASTIC FILM
Authors: ZHENG Z. W. , SRIDHAR I. , JOHNSON K. L. , ANG W. T.
Published: December 2004

The Johnson–Kendal–Roberts (JKR) adhesion theory is frequently applied to extract the surface energy of the contacting thin coating systems in micro or nanoprobe instruments such as Surface Force Apparatus (SFA) and Atomic Force Microscope (AFM). For thin-layer systems, the JKR theory may give rise to erroneous predictions as it is based on the elastic contact between a sphere and a half-space. Adhesion between the thin-layer surfaces has been analyzed by Sridhar et al. using a numerical SJF (Sridhar–Johnson–Fleck) model. In this paper, the adhesion between a spherical tip of an AFM and an incompressible thin elastic film is investigated. When the substrate is rigid, the normalised pull-off force may differ from the JKR value of -0.5 by as much as 90%. Computations of the contact size and pull-off force are presented for a range of values of adhesion energy. Finally, an empirical equation for the adhesive load was developed by curve fitting the compliance of the layer system as a function of contact radius.
SURFACE CHEMICAL STATES OF HETEROEPITAXIAL NITRIDE FILMS ON SAPPHIRE BY METALORGANIC CHEMICAL VAPOR DEPOSITION
Authors: LI K. , FENG Z. C. , YANG C.-C. , LIN J.
Published: December 2004

Surface chemical states of GaN , AlGaN and InGaN by metalorganic chemical vapor deposition, and the influence of different dopants are studied with X-ray Photoelectron Spectroscopy (XPS). The results show that for most of the samples the N 1s peak can be fitted with a dominant GaN peak and a small N – H peak, while Ga 3d can be deconvoluted into three peaks from elemental Ga , GaN and Ga 2 O 3. Si -doping appears to have small influence on the surface chemical states of GaN while the influence of Mg -doping appears larger. In addition to a change in the component intensities, Mg -doping also causes the N 1s and Ga 3d peaks to broaden. The ternary AlGaN sample shows aluminum surface segregation, while the undoped InGaN shows indium surface deficiency.
EFFECTS OF HEAT TREATMENT ON SYNTHETIC GRAPHITES FOR CARBON NANOTUBES SYNTHESIS
Authors: SANIP S. M. , ABIDIN Z. R. Z. , BUANG N. , AZIZ M. , ISMAIL A. F.
Published: December 2004

Carbon materials are well known for their excellent adsorbent property towards gases. Much work has been done to improve the properties of carbon materials as to enhance their absorption capacity towards gases. Recent developments have resulted in the discovery of novel carbon materials such as carbon nanotubes. Numerous researches have shown that carbon nanotubes have excellent capacity for hydrogen storage. However, significant research has been undertaken to further improve the adsorption capacity through the advancement in synthesis methods for the fabrication of carbon nanotubes. Among the starting material widely employed for synthesis of carbon nanotubes is high purity graphite. Therefore, purpose of this work is to investigate the effect of thermal treatment on several synthetic graphites. Thermal treatment was conducted at temperatures ranging from 400–800°C at different dwelling times. The morphology and surface analysis of the graphites were examined using Scanning Electron Microscope and nitrogen gas adsorption techniques, respectively. It was found that temperature, time and conditions of treatment significantly change the surface structure of the graphites. A decrease in particle size was observed due to the release of internal surface area.
Proinflammatory properties of IL-4 in the intestinal microenvironment
Authors: Van Kampen C. , Gauldie J. , Collins S. M.
Published: December 2004

IL-4 is involved in type 2 T helper cell (Th)2-type immune responses and, in some cases, can promote Th1 responses. However, the proinflammatory potential of IL-4 alone is unclear. In this study, we examined the ability of IL-4 to induce colitis after its overexpression in the colon using an adenoviral vector (Ad5) and compared results with those obtained after overexpression of IL-12, a cytokine implicated in several models of colitis. Overexpression of IL-4 or IL-12 caused a fatal colitis within 24 h in 60% of animals and was dose and strain dependent. IL-12-induced colitis was accompanied by the local expression of IFN-γ and TNF-α but not IL-4 mRNA and protein. Conversely, IL-4-induced colitis was accompanied by the local expression of IL-4 and TNF-α but not IFN-γ mRNA and protein. The Ad5-IL4-induced colitis did not persist beyond 3 days and was present in recombinase activation gene-2 (RAG-2)−/− mice but not in STAT6−/− mice. Acute lethal colitis induced by Ad5IL12 was T cell mediated and IFN-γ receptor (IFN-γR) dependent. Furthermore, TNF-α was found to be important in the pathogenesis of Ad5IL-4 and Ad5IL-12-induced colitis. Results of this study indicate that IL-4 alone can act as a proinflammatory cytokine in the gut of normal mice, inducing a rapid onset and short-lived colonic injury while maintaining a Th2-type cytokine profile that functions via a local T cell-independent mechanism involving TNF-α.
FXR-activating ligands inhibit rabbit ASBT expression via FXR-SHP-FTF cascade
Authors: Li Hai , Chen Frank , Shang Quan , Pan Luxing , Shneider Benjamin L. , Chiang John Y. L. , Forman Barry M. , Ananthanarayanan M. , Tint G. Stephen , Salen Gerald , Xu Guorong
Published: December 2004

The regulation of the rabbit apical sodium-dependent bile acid transporter (ASBT) was studied both in vivo and in vitro. New Zealand White rabbits were fed 0.5% deoxycholic acid (DCA) or SC-435, a competitive ASBT inhibitor, for 1 wk. In DCA-fed rabbits, ASBT expression was repressed, associated with activated FXR, and evidenced by increased ileal short heterodimer partner (SHP) mRNA. Feeding SC-435 to the rabbits blocked bile acid absorption, decreased SHP mRNA, and increased ASBT expression. A 1.9-kb rabbit ASBT 5′-flanking region (promoter) was cloned, and a cis-acting element for α-fetoprotein transcription factor (FTF) was identified (−1166/ −1158). The effects of transcriptional factors and different bile acids on the rabbit ASBT promoter were studied in Caco-2 cells. FTF stimulated the rabbit ASBT promoter activity fourfold but not after the FTF binding site was deleted from the promoter. Increasing the SHP protein notably inhibited FTF-dependent trans-activation of rabbit ASBT. Adding hydrophobic bile acids deoxycholic acid, chenodeoxycholic acid, and cholic acid, activating ligands for FXR, inhibited rabbit ASBT promoter activity in Caco-2 cells, but this inhibitory effect was abolished after the FTF binding site was deleted. Ursodeoxycholic acid and ursocholic acid, nonactivating ligands for FXR, did not repress ASBT promoter activity. Thus the rabbit ASBT promoter is negative-feedback regulated by bile acids via a functional FTF binding site. Only FXR-activating ligands can downregulate rabbit ASBT expression through the regulatory cascade FXR-SHP-FTF.
Dual oxidase2 is expressed all along the digestive tract
Authors: El Hassani Rabii Ameziane , Benfares Nesrine , Caillou Bernard , Talbot Monique , Sabourin Jean-Christophe , Belotte Virginie , Morand Stanislas , Gnidehou Sédami , Agnandji Diane , Ohayon Renée , Kaniewski Jacques , Noël-Hudson Marie-Sophie , Bidart Jean-Michel , Schlumberger Martin , Virion Alain , Dupuy Corinne
Published: December 2004

The dual oxidase (Duox)2 flavoprotein is strongly expressed in the thyroid gland, where it plays a critical role in the synthesis of thyroid hormones by providing thyroperoxidase with H2O2. DUOX2 mRNA was recently detected by RT-PCR and in-situ hybridization experiments in other tissues, such as rat colon and rat and human epithelial cells from the salivary excretory ducts and rectal glands. We examined Duox2 expression at the protein level throughout the porcine digestive tract and in human colon. Western blot analysis identified Duox2 as the same two molecular species ( Mr 165 and 175 kDa) as detected in the thyroid. It was expressed in all the tissues tested, but the highest levels were found in the cecum and sigmoidal colon. Immunohistochemical studies showed that Duox2 protein is mainly present in these parts of the gut and located at the apical membrane of the enterocytes in the brush border, indicating that it is expressed only in highly differentiated cells. A Ca2+/NADPH-dependent H2O2-generating system was associated with Duox2 protein expression, which had the same biochemical characteristics as the NADPH oxidase in the thyroid. Indeed, treatment of the thyroid and cecum particulate fractions with phenylarsine oxide resulted in complete calcium desensitization of both enzymes. A marked increase in DUOX2 expression was also found during spontaneous differentiation of postconfluent Caco-2 cells. The discovery of Duox2 as a novel source of H2O2 in the digestive tract, particularly in the cecum and colon, makes it a new candidate mediator of physiopathological processes.
Effects of copper supplementation on copper absorption, tissue distribution, and copper transporter expression in an infant rat model
Authors: Bauerly Kathryn A. , Kelleher Shannon L. , Lönnerdal Bo
Published: December 2004

Infants are exposed to variable copper (Cu) intake; Cu in breast milk is low, whereas infant formulas vary in Cu content as well as the water used for their preparation. Little is known about the regulation of Cu absorption during infancy. The objectives of this study were to determine effects of Cu supplementation on Cu absorption and tissue distribution and the expression of Cu transporters in an infant rat model. Suckling rat pups were orally dosed with 0, 10, or 25 μg Cu/day. Intestine and liver were collected at days 10 and 20, and Cu concentration, Cu transporter-1 (Ctr1), Atp7A, Atp7B, and metallothionein (MT) mRNA and protein levels were measured.67Cu absorption was measured at days 10 and 20. Total67Cu absorption decreased, and intestinal67Cu retention increased with increased Cu intake. At day 10, intestine Cu concentration, MT mRNA, and Ctr1 protein levels increased with supplementation, but no changes in Atp7A or Atp7B levels were observed. At day 20, intestine Cu concentration was unaffected by Cu supplementation, but Ctr1 protein and Atp7A mRNA and protein levels were higher than in controls. In liver, Cu level reflected Cu intake at days 10 and 20. There was a significant increase in Ctr1, Atp7B, and MT mRNA expression in liver at both ages with Cu supplementation. In conclusion, the ability of suckling rat pups to tolerate varying amounts of dietary Cu may be due to changes in Cu transporters, facilitated by transcriptional and posttranslational mechanisms. Despite these adaptive changes, Cu supplementation resulted in elevated alanine aminotransferase levels, suggesting a risk of Cu toxicity with supplementation during infancy.
Signaling pathways mediating gastrointestinal smooth muscle contraction and MLC20 phosphorylation by motilin receptors
Authors: Huang Jiean , Zhou Huiping , Mahavadi Sunila , Sriwai Wimolpak , Lyall Vijay , Murthy Karnam S.
Published: December 2004

The signaling cascades initiated by motilin receptors in gastric and intestinal smooth muscle cells were characterized. Motilin bound with high affinity (IC50 0.7 ± 0.2 nM) to receptors on smooth muscle cells; the receptors were rapidly internalized via G protein-coupled receptor kinase 2 (GRK2). Motilin selectively activated Gq and G13, stimulated Gαq-dependent phosphoinositide (PI) hydrolysis and 1,4,5-trisphosphate (IP3)-dependent Ca2+ release, and increased cytosolic free Ca2+. PI hydrolysis was blocked by expression of Gαq minigene and augmented by overexpression of dominant negative RGS4(N88S) or GRK2(K220R). Motilin induced a biphasic, concentration-dependent contraction (EC50 = 1.0 ± 0.2 nM), consisting of an initial peak followed by a sustained contraction. The initial Ca2+-dependent contraction and myosin light-chain (MLC)20 phosphorylation were inhibited by the PLC inhibitor U-73122 and the MLC kinase inhibitor ML-9 but were not affected by the Rho kinase inhibitor Y27632 or the PKC inhibitor bisindolylmaleimide. Sustained contraction and MLC20 phosphorylation were RhoA dependent and mediated by two downstream messengers: PKC and Rho kinase. The latter was partly inhibited by expression of Gαq or Gα13 minigene and abolished by coexpression of both minigenes. Sustained contraction and MLC20 phosphorylation were partly inhibited by Y27632 and bisindolylmaleimide and abolished by a combination of both inhibitors. The inhibition reflected phosphorylation of two MLC phosphatase inhibitors: CPI-17 via PKC and MYPT1 via Rho kinase. We conclude that motilin initiates a Gαq-mediated cascade involving Ca2+/calmodulin activation of MLC kinase and transient MLC20 phosphorylation and contraction as well as a sustained Gαq- and Gα13-mediated, RhoA-dependent cascade involving phosphorylation of CPI-17 by PKC and MYPT1 by Rho kinase, leading to inhibition of MLC phosphatase and sustained MLC20 phosphorylation and contraction.
Reduction of infarct size and postischemic inflammation from ATL-146e, a highly selective adenosine A2Areceptor agonist, in reperfused canine myocardium
Authors: Glover David K. , Riou Laurent M. , Ruiz Mirta , Sullivan Gail W. , Linden Joel , Rieger Jayson M. , Macdonald Timothy L. , Watson Denny D. , Beller George A.
Published: December 2004

Adenosine and adenosine A2Areceptor agonists have been shown to limit myocardial infarct size when given at vasodilatory doses during reperfusion. This beneficial effect is thought to be due, in part, to stimulation of adenosine A2Areceptors on inflammatory cells. The specific aims of this study were to determine whether the anti-inflammatory and cardioprotective properties of a novel adenosine A2Areceptor agonist, ATL-146e (ATL), alone or in combination with the phosphodiesterase IV inhibitor rolipram would occur using very low, nonvasodilating doses. In a canine model of reperfused myocardial infarction, low-dose ATL given alone reduced infarct size by 45% ( P < 0.05 vs. control). When ATL was combined with a very low dose of rolipram (0.001 μg·kg−1·min−1), a marked reduction in P-selectin expression and neutrophil infiltration (51% lower; P < 0.001 vs. control) was seen and the infarct size reduction (58% lower; P < 0.01 vs. control) was greater than observed with ATL (45% lower; P < 0.05) or rolipram (33% lower; P < 0.05) alone. In conclusion, a low, nonvasodilating dose of ATL, a highly selective adenosine A2Areceptor agonist, reduced infarct size after reperfusion. Furthermore, combining ATL and the phosphodiesterase IV inhibitor rolipram reduced infarct size even more than either agent alone. Such combination therapy may be beneficial clinically by potentiating cardioprotection after coronary reperfusion at doses far below those producing vasodilatation or side effects.
Strain-induced vascular endothelial cell proliferation requires PI3K-dependent mTOR-4E-BP1 signal pathway
Authors: Li Wei , Sumpio Bauer E.
Published: December 2004

The aim of this study was to determine whether the phosphatidylinositol 3-kinase (PI3K)-dependent mammalian target of rapamycin (mTOR)-eukaryotic initiation factor 4E binding protein 1 (4E-BP1) signal pathway and S6 kinase (S6K), the major element of the mTOR pathway, play a role in the enhanced vascular endothelial cell (EC) proliferation induced by cyclic strain. Bovine aortic ECs were subjected to an average of 10% strain at a rate of 60 cycles/min for ≤24 h. Cyclic strain-induced EC proliferation was reduced by pretreatment with rapamycin but not the MEK1 inhibitor PD-98059. The PI3K inhibitors wortmannin and LY-294002 also attenuated strain-induced EC proliferation and strain-induced activation of S6K. Rapamycin but not PD-98059 prevented strain-induced S6K activation, and PD-98059 but not rapamycin prevented strain-induced activation of extracellular signal-regulated kinases 1 and 2. Cyclic strain also activated 4E-BP1, which could be inhibited by PI3K inhibitors. These data suggest that the PI3K-dependent S6K-mTOR-4E-BP1 signal pathway may be critically involved in strain-induced bovine aortic EC proliferation.