bluuebunny/crossref_metadata_2025 huggingface dataset:
The HIV protease inhibitor ritonavir synergizes with butyrate for induction of apoptotic cell death and mediates expression of heme oxygenase‐1 in DLD‐1 colon carcinoma cells
Authors: Mühl Heiko , Paulukat Jens , Höfler Sonja , Hellmuth Markus , Franzen Rochus , Pfeilschifter Josef
Published: November 2004

The protease inhibitor ritonavir is an integral part of current antiretroviral therapy targeting human immunodeficiency virus. Recent studies demonstrate that ritonavir induces apoptotic cell death with high efficiency in lymphoblastoid cell lines. Moreover, ritonavir can suppress activation of the transcription factor nuclear factor‐κB and is an inhibitor of interleukin‐1β and tumor necrosis factor‐α production in peripheral blood mononuclear cells. Thus, ritonavir appears to have anti‐inflammatory properties.

In the present study, we investigated in DLD‐1 colon carcinoma cell effects of ritonavir on apoptotic cell death and expression of heme oxygenase‐1 (HO‐1), an anti‐inflammatory enzyme that may be critically involved in the modulation of colonic inflammation.

Compared to unstimulated control, ritonavir resulted in a moderate increase in the rate of apoptotic cell death as observed after 20 h of incubation. Notably, ritonavir potently synergized with the short‐chain fatty acid butyrate for induction of caspase‐3‐dependent apoptosis in DLD‐1 cells.

Ritonavir enhanced mRNA and protein expression of HO‐1 in DLD‐1 cells. Ritonavir‐induced HO‐1 protein was suppressed by SB203580 or SB202190 and preceded by immediate upregulation of cellular c‐Fos and c‐Jun protein levels. This process was associated with induction of activator protein‐1 as detected by electrophoretic mobility shift analysis.

The present data suggest that ritonavir has the potential to curb colon carcinogenesis by reducing cell growth via mechanisms that include apoptosis and by simultaneously modulating colonic inflammation via induction of anti‐inflammatory HO‐1.

British Journal of Pharmacology (2004) 143, 890–898. doi:10.1038/sj.bjp.0706023
Development of an adsorption procedure for the direct separation and purification of prodigiosin from culture broth
Authors: Wang Xuedong , Tao Jinli , Wei Dongzhi , Shen Yaling , Tong Wangyu
Published: November 2004

A novel procedure for the direct separation and purification of prodigiosin based on adsorption chromatography is provided. A surfactant (Tween 80; 0.1%, w/v) was used to improve prodigiosin release from the cell envelope. An adsorbent (X‐5 resin) with high loading capacity (7.3 mg/g) was selected for the direct recovery of prodigiosin from culture broth by static adsorption or in situ separation. This technology not only simplified the separation process, but also made the recovery yield (83%) much higher when compared with the conventional method (50%). As a result, it will be particularly suited for large‐scale separation and purification of prodigiosin.
Purification and biochemical characterization of a thermostable, alkaliphilic, extracellular α‐amylase fromBacillus subtilisDM‐03, a strain isolated from the traditional fermented food of India
Authors: Das Kishore , Doley Robin , Mukherjee Ashis Kumar
Published: November 2004

Bacillus subtilisstrain DM‐03, which is isolated from starter culture used for the production of alcohol by local Assam tribes, grows optimally at 52–55 °C and secretes a significant amount of α‐amylase at pH 8.0 into the culture media. This α‐amylase, purified by ion‐exchange, gel‐filtration and reverse‐phase HPLC, constitutes 2.9% of the total extracellular protein. This purified enzyme, named Bsamy‐I, has a subunit with molecular mass of 42.8 kDa as determined by SDS/PAGE, and optimum temperature and pH values at 52–55 °C and 9.0 respectively, which makes it ideal for use in the detergent industries. Maximum α‐amylase production is obtained by using soluble starch and NH4Cl as carbon and nitrogen sources respectively. Thermostability of the enzyme is evident from heating the enzyme at 95 °C for 10 min, which results in a loss of 60% of the original enzyme activity. 4‐Bromophenacyl bromide and PMSF at 4 and 1.5 mM concentration respectively completely abolish the enzymic activity, documenting the essential role of histidine and carboxylic residues in the catalytic process.
Kinase-independent transcriptional co-activation of peroxisome proliferator-activated receptor α by AMP-activated protein kinase
Authors: BRONNER Myriam , HERTZ Rachel , BAR-TANA Jacob
Published: November 2004

AMPK (AMP-activated protein kinase) responds to intracellular ATP depletion, while PPARα (peroxisome proliferator-activated receptor α) induces the expression of genes coding for enzymes and proteins involved in increasing cellular ATP yields. PPARα-mediated transcription is shown here to be co-activated by the α subunit of AMPK, as well as by kinase-deficient (Thr172Ala) and kinase-less (Asp157Ala, Asp139Ala) mutants of AMPKα. The Ser452Ala mutant of mPPARα mutated in its putative consensus AMPKα phosphorylation site is similarly co-activated by AMPKα. AMPKα or its kinase-less mutants bind to PPARα; binding is increased by MgATP, to a lesser extent by MgADP, but not at all by AMP or ZMP [AICAR (5-aminoimidazole-4-carboxamide ribonucleoside) monophosphate]. ATP-activated binding of AMPKα to PPARα is mediated primarily by the C-terminal regulatory domain of AMPKα. PPARα co-activation by AMPKα may, however, require its secondary interaction with the N-terminal catalytic domain of AMPKα, independently of its kinase activity. While AMPK catalytic activity is activated by AICAR, PPARα co-activation and PPARα-controlled transcription are robustly inhibited by AICAR, with concomitant translocation of nuclear AMPKα or its kinase-less mutants to the cytosol. In conclusion, AMPKα, independently of its kinase activity, co-activates PPARα both in primary rat hepatocytes and in PPARα-transfected cells. The kinase and transcriptional co-activation modes of AMPKα are both regulated by the cellular ATP/AMP ratio. Co-activation of PPARα by AMPKα may transcriptionally complement AMPK in maintaining cellular ATP status.
Identification of two novel microalgal enzymes involved in the conversion of the ω3-fatty acid, eicosapentaenoic acid, into docosahexaenoic acid
Authors: PEREIRA Suzette L. , LEONARD Amanda E. , HUANG Yung-Sheng , CHUANG Lu-Te , MUKERJI Pradip
Published: November 2004

Marine microalgae such as Pavlova and Isochrysis produce abundant amounts of the ω3-PUFAs (polyunsaturated fatty acids), EPA (eicosapentaenoic acid, 20:5n–3) and DHA (docosahexaenoic acid, 22:6n–3). The pathway leading to the conversion of EPA into DHA in these lower eukaryotes is not well established although it is predicted to involve an elongation step, catalysed by an elongating enzyme complex, leading to the conversion of EPA into ω3-DPA (ω–3-docosapentaenoic acid, 22:5n–3); followed by a desaturation step, catalysed by a Δ4-desaturase, which results in the conversion of DPA into DHA. To date, the enzymes involved in the elongation of EPA have not been identified from any lower eukaryote. In the present study, we describe the identification of microalgal genes involved in the two-step conversion of EPA into DHA. By expressed sequence tag analysis, a gene (pavELO) encoding a novel elongase was identified from Pavlova, which catalysed the conversion of EPA into ω3-DPA in yeast. Unlike any previously identified elongase from higher or lower eukaryotes, this enzyme displayed unique substrate specificity for both n–6 and n–3 C20-PUFA substrates, with no activity towards any C18- or C22-PUFA substrates. In addition, a novel Δ4-desaturase gene (IgD4) was isolated from Isochrysis, which was capable of converting ω3-DPA into DHA, as well as adrenic acid (22:4n–6) into ω6-DPA. Yeast co-expression studies, with pavELO and IgD4, revealed that these genes were capable of functioning together to carry out the two-step conversion of EPA into DHA.
Cardiovascular risk factors and endothelial dysfunction
Authors: WIERZBICKI Anthony S. , CHOWIENCZYK Philip J. , COCKCROFT John R. , BRETT Sally E. , WATTS Gerald F. , JENKINS B. Stephen , RITTER James M.
Published: November 2004

Endothelial dysfunction is a feature of atherosclerosis and is associated with CHD (coronary heart disease) risk factors. This study aimed to determine the relationship between the degree of endothelial dysfunction and calculated cardiovascular risk. Endothelial function, as determined by the ACh/NP (acetycholine/sodium nitroprusside response) ratio on brachial plethysmography, was compared with cardiovascular risk as calculated from the Framingham, PROCAM (Prospective Cardiovascular Munster) and MRFIT (Multiple Risk Factor Intervention Trial) algorithms in 246 (187 male) patients, including 44 (22%) with established CHD. Endothelial dysfunction correlated with the total number of risk factors (r2=0.22; P=0.002) and was related to LDL (low-density lipoprotein)-cholesterol in men and triacylglycerols (triglycerides) in women. The ACh/NP ratio correlated with the occurrence of diabetes, CHD and the LDL-cholesterol concentration (r2=0.58; P<0.001). Endothelial dysfunction was associated with presence of CHD on receiver-operating characteristic plot analysis (area=0.706±0.04; P=0.001). There was no correlation between ACh/NP ratio and CHD risk calculated with the Framingham algorithm in men, although both ACh and NP response correlated separately with risk in women. The endothelial ACh/NP ratio correlated with absolute risk in the PROCAM algorithm (r2=0.41; P<0.005). Intermediate results were obtained with MRFIT. Individual risk factors make different contributions to endothelial dysfunction compared with their role in risk calculators. The stronger relationship of endothelial dysfunction with PROCAM risk reflects the contribution of male sex, LDL-cholesterol and triacylglycerols to risk calculated by this algorithm.
Evidence against redox regulation of energy homoeostasis in humans at high altitude
Authors: BAILEY Damian M. , AINSLIE Philip N. , JACKSON Simon K. , RICHARDSON Russell S. , GHATEI Mohammed
Published: November 2004

The present study examined if free radicals and associated inflammatory sequelae influenced metabolic biomarkers involved in the neuro-endocrinological regulation of energy homoeostasis at high altitude. Sixteen mountaineers (11 males/five females) were matched for physical fitness and caloric intake and assigned in a double-blind manner to either antioxidant (n=8) or placebo (n=8) supplementation, which was enforced for 7 days at sea level and during an 11-day ascent to 4780 m. Enteral prophylaxis incorporated a daily bolus dose of 1 g of L-ascorbate, 400 international units of D,L-α-tocopherol acetate and 600 mg of α-lipoic acid. EPR (electron paramagnetic resonance) spectroscopic detection of PBN (α-phenyl-tert-butylnitrone) adducts confirmed an increase in the venous concentration of carbon-centred radicals at high altitude in the placebo group, whereas a decrease was observed in the antioxidant group (P<0.05 compared with that at sea level). EPR detection of DMSO/A˙− (DMSO-supplemented ascorbate free radical) demonstrated that the increase in carbon-centred radicals at high altitude was associated with a decrease in ascorbate (r2=0.63; P<0.05). Ascent to high altitude (pooled placebo+antioxidant groups) also increased the expression of pro-inflammatory cytokines (P<0.05 compared with that at sea level) and biomarkers of skeletal tissue damage (P<0.05). Despite a general decrease in leptin, insulin and glucose at high altitude (pooled placebo+antioxidant groups; P<0.05 compared with that at sea level), persistent anorexia resulted in a selective loss of body fat (P<0.05). In conclusion, antioxidant prophylaxis decreased the concentration of carbon-centred radicals at high altitude (P<0.05 compared with the placebo group), but did not influence markers of inflammation, appetite-related peptides, ad libitum nutrient intake or body composition. Thus free radicals do not appear to be involved in the inflammatory response and subsequent control of eating behaviour at high altitude.
The cellular basis of albuminuria
Authors: MATHIESON Peter W.
Published: November 2004

The appearance of albumin in the urine has long been recognized as a cardinal feature of kidney disease and more recently has been shown to also be an independent cardiovascular risk factor associated with insulin resistance. Recent studies on rare human genetic variants, targeted gene disruption in mouse models and cultured glomerular cells in vitro have dramatically improved our understanding of the cellular and molecular basis of albuminuria. This review aims to summarize the current state of knowledge, to illustrate known mechanisms of proteinuria in disease states and to suggest a possible explanation for the link between albuminuria and insulin resistance.
Low energy electron cooling induced by a magnetic field in high pressure capacitive radio frequency discharges
Authors: You S. J. , Kim S. S. , Chang H. Y.
Published: November 2004

A study is conducted on a magnetic field effect on electron heating in capacitive rf discharges under a collisional regime, where the electron mean collision frequency is much higher than the rf frequency. The evolution of an electron energy distribution function (EEDF) over a magnetic field range of 0–30G in 300mTorr Ar discharges is measured and calculated for the investigation. A significant change in the low-energy range of the EEDF is found during the evolution. The observed result reveals the application of the magnetic field to the high-pressure capacitive plasma gives rise to a cooling effect on the low-energy electrons. This is in contrast to the low-pressure case where the magnetic field enhances the low-energy electron heating. The calculated result of the EEDF is in good agreement with the experiment.
Size self-scaling effect in stacked InAs∕InAlAs nanowire multilayers
Authors: Sun Z. Z. , Yoon S. F. , Wu J. , Wang Z. G.
Published: November 2004

Size self-scaling effect in stacked InAs∕In0.52Al0.48As nanowires on InP substrates is revealed, i.e., the base width and height of the InAs nanowires have clear proportional dependence on thickness of the InAlAs spacer layer used in different samples. The photoluminescence wavelength from different samples, which varies between 1.3 and 1.9μm, is also found closely correlated to the size self-scaling effect. This phenomenon can be well explained in the context of formation mechanism and growth features of the InAs∕InAlAs nanowire arrays. The finding illustrates a degree of freedom to control the structural and optical properties of strained self-organized nanostructures.
Megasonic-assisted development of nanostructures: Investigations on high aspect ratio nanoholes
Authors: Küpper David , Küpper Daniel , Georgiev Yordan M. , Wahlbrink Thorsten , Henschel Wolfgang , Bell Guido , Kurz Heinrich
Published: November 2004

The influence of megasonic agitation on the development of nanostructures with high aspect ratio is investigated thoroughly. The improvements in homogeneity, depth, and quality of nanostructures are related to specific interactions of the sound wave with the resist and developer. Two phases in the development process are operative. The specific role of microstreaming providing physical supply of fresh developer is identified and the reduction of viscosity by megasonic interaction is derived. The advantage of megasonic agitation as a nondestructive development of high aspect ratio nanostructures is demonstrated.
Unique architecture and concept for high-performance organic transistors
Authors: Ma Liping , Yang Yang
Published: November 2004

We report an organic transistor with a vertically stack structure, which consists of a layer-by-layer active cell (drain/organics/source) on top of a capacitor cell (source/dielectrics/gate); the middle source electrode is shared by the capacitor cell and active cell. Three unique characteristics of this transistor, (a) its very thin and rough middle source electrode; (b) its capacitor cell with high charge-storage capability, allow the active cell to be influenced when the gate is biased; and (c) the large cross-section area and small distance between the source and the drain allow current flowing between the source and drain electrodes. Devices have been fabricated by thermal evaporation with the source-drain current well modulated by the gate potential. We have achieved organic transistors with low working voltage (less than 5V) and high current output (up to 10mA or 4A∕cm2) and an ON/OFF ratio of 4×106. A model is proposed for the device operation mechanism. The demonstrated device with its enhanced operating characteristics may open directions for organic transistors and their applications.
Interaction between organic semiconductors and LiF dopant
Authors: Yuan Y. , Grozea D. , Han S. , Lu Z. H.
Published: November 2004

X-ray photoemission spectroscopy and optical absorption have been used to study the interaction between LiF dopant and various organic semiconductor hosts including N,N′-diphenyl-N,N′-bis (3-methylphenyl)-1, 1′-biphenyl-4, 4′-diamine (TPD), N,N′-bis (1-naphthyl)-N,N′-diphenyl-1, 1′-biphenyl-4, 4′-diamine (NPB), tris (8-hydroxyquinolinato) aluminum (Alq3), C60, and copper phthalacyanine (CuPc). It was found that there is a charge transfer between host and dopant in the Alq3–LiF and C60–LiF systems, while no such charge transfer was observed for the TPD–LiF, NPB–LiF, and CuPc–LiF systems. The experimental data show that F− anion acts as an n-type donor—donating electron charge to the electron transport molecules.
Self-assembled carbon-nanotube-based field-effect transistors
Authors: Hazani Miron , Shvarts Dmitry , Peled Dana , Sidorov Victor , Naaman Ron
Published: November 2004

Self-assembled carbon-nanotube-based field-effect transistors (CNTFETs) were produced with high yield using the natural process of DNA hybridization. In principle, the devices made by this method behave like those made using direct metal-carbon nanotube contacts. The inverse subthreshold slope of the CNTFETs depends on the source-drain voltage applied to the device, confirming that the conductance of CNTFETs is determined by the Schottky barriers at the interfaces between the CNTs and the gold electrodes.
Effects of annealing temperature on electrical resistance of bonded n-GaAs wafers
Authors: Liu Po Chun , Lu Cheng Lun , Wu YewChung Sermon , Cheng Ji-Hao , Ouyang Hao
Published: November 2004

The electrical characteristics and microstructures of n-type (100) GaAs bonded interfaces were systematically investigated. Experimental results indicated that GaAs did not bond directly to itself, but via an amorphous oxide layer at 400°C. When temperatures increased above 400°C, the oxide bonded area declined and finally disappeared. Electrical resistance decreased with bonding temperature. However, the resistance increased with temperatures exceeding 850°C.
Gate-alloy-related kink effect for metamorphic high-electron-mobility transistors
Authors: Chen Y. J. , Hsu W. C. , Lee C. S. , Wang T. B. , Tseng C. H. , Huang J. C. , Huang D. H. , Wu C. L.
Published: November 2004

Gate-metal-related kink effects in InAlAs ∕ InGaAs ∕ GaAs metamorphic high-electron-mobility transistors have been investigated. Improvements on the kink effect have been observed by using the higher Schottky barrier height gate alloys, including Ti∕Au, Ni∕Au, and Pt∕Au, as compared to the use of the conventional Au gate metal. In comparison with gate alloy combinations, the devices with Ti∕Au alloy exhibit superior noise characteristics, whereas those with Ni∕Au alloy demonstrate the highest power characteristics. With the gate dimensions of 1.2×200μm2, the device minimum noise figure, NFmin, is 1.17dB at 2.4GHz by using Ti∕Au and the output power is 13.14dBm at 2.4GHz by using Ni∕Au. Significant rf characteristics have also been improved upon that with Au gate.
Artificial ferroelectricity in perovskite superlattices
Authors: Tsurumi Takaaki , Harigai Takakiyo , Tanaka Daisuke , Nam Song-Min , Kakemoto Hirofumi , Wada Satoshi , Saito Keisuke
Published: November 2004

Artificial superlattices of SrZrO3(SZO)∕SrTiO3(STO) were fabricated by molecular-beam epitaxy. Lattice parameters showed that the lattice distortion (c∕a ratio) attained a maximum value in the [(SZO)10∕(STO)10]4 superlattice. Dielectric relaxation was observed in the [(SZO)1∕(STO)1]40 and [(SZO)10∕(STO)10]4 superlattices in the low frequency domain. Dielectric permittivity of the SZO∕STO superlattices was over 10 000 at 110MHz. The SZO∕STO superlattices showed clear Q–V hysteresis curves, which indicated that ferroelectricity was induced artificially in the superlattices in spite of the paraelectric nature of SZO and STO. The origin of the ferroelectricity was related to the anisotropic lattice distortion in the superlattice structure.
Microdischarge devices with 10 or 30μm square silicon cathode cavities: pd scaling and production of the XeO excimer
Authors: Park S.-J. , Eden J. G. , Chen J. , Liu C.
Published: November 2004

Silicon microplasma devices with square trench cathode cavities having cross sections of (10μm)2 or (30μm)2 and a depth of 200μm have been fabricated and operated successfully in the rare gases and Xe∕O2 mixtures at pressures (300K) up to 1100Torr. The (10μm)2 structures exhibit electrical characteristics that contrast with the behavior of larger devices and may indicate the onset of the breakdown of pd scaling. Also, a distinct minimum in the ignition voltage of 10μm square devices is observed for pd≃0.9Torrcm (p and d are the Ne gas pressure and microcavity cross-sectional dimension, respectively). Strong emission on the 2∑+1→1∑+1 transition of XeO in the green (∼510–560nm) is observed in mixtures of Xe(300–700Torr) and O2(1–10mTorr).
Thickness determination of very thin amorphous and microcrystalline silicon layers using reflection/transmission measurements
Authors: Gordijn A. , Rath J. K. , Schropp R. E. I.
Published: November 2004

In thin-film silicon research, it is essential to have an accurate and fast method for the determination of the thickness and material properties of layers down to 20nm thick. We report on the interpretation of optical measurements by spectroscopy of reflection and transmission in the range 400–1000nm. A method is developed to fit these spectra based on the O’Leary–Johnson–Lim model and material properties obtained from thicker layers. These results are correlated with the results obtained from other techniques for accurate thickness measurements. We conclude that a reliable fit of the optical measurements is possible down to a layer thickness of 20nm.
On-site manipulation of single whole-genome DNA molecules using optical tweezers
Authors: Oana Hidehiro , Kubo Koji , Yoshikawa Kenichi , Atomi Haruyuki , Imanaka Tadayuki
Published: November 2004

In this letter, we describe a noninvasive methodology for manipulating single Mb-size whole-genome DNA molecules. Cells were subjected to osmotic shock and the genome DNA released from the burst cells was transferred to a region of higher salt concentration using optical tweezers. The transferred genome DNA exhibits a conformational transition from a compact state into an elongated state, accompanied by the change in its environment. The applicability of optical tweezers to the on-site manipulation of giant genome DNA is suggested, i.e., lab-on-a-plate.
Radiation-induced zero-resistance states with resolved Landau levels
Authors: Mani R. G.
Published: November 2004

The microwave-photoexcited high mobility GaAs∕AlGaAs two-dimensional electron system exhibits an oscillatory magnetoresistance with vanishing resistance in the vicinity of magnetic fields B=[4∕(4j+1)]Bf, where Bf=2πfm*∕e, m* is an effective mass, e is the charge, f is the microwave frequency, and j=1,2,3… Here, we report transport with well-resolved Landau levels, and some transmission characteristics.
Structural and magnetic phase stability of Si∕MnAs superlattices: Tetragonal-distortion-induced ferromagnetism and half-metallicity
Authors: Kim Miyoung , Freeman A. J.
Published: November 2004

The structural and magnetic phase stabilities of a Si(001)∕MnAs superlattice have been investigated using the highly precise all-electron full-potential linearized augmented plane-wave method within the generalized gradient approximation. From a total energy and atomic force calculations, we found that the zincblende structure for MnAs is most stable over other atomic configurations, where either Mn or As layers are attached to the Si interface. The antiferromagnetic (AFM) coupling between the Mn atoms is calculated to be energetically favored over the ferromagnetic (FM) coupling by a total energy difference of 40meV∕unit cell. More interestingly, we predict that a 2% tetragonal distortion from its AFM crystal structure induces a magnetic phase transition from the AFM to a half-metallic FM phase with a 0.36eV band gap for the minority spin channel, which indicates a promising possible spintronics application.
Interaction between interstitials and arsenic-vacancy complexes in crystalline silicon
Authors: Harrison Scott A. , Edgar Thomas F. , Hwang Gyeong S.
Published: November 2004

Using density functional theory calculations, we have examined the interaction of interstitials with various arsenic-vacancy complexes and compared these events to interstitial-vacancy (I-V) interactions. We find that the vacancy of AsmV(m=1–4) and AsmV2(m=2,3) complexes is easily annihilated by I-V recombination, with barriers of 0–0.08 eV and 0.16–0.21 eV, respectively, for the mono- and the di-vacancy associated complexes. The energy gain from the I-V recombination turns out to be significant (>1.3eV), implying that As would remain more favorably as Asn (or AsmIn) complexes, rather than as AsmVn in the presence of a large amount of excess interstitials. This suggests that interstitials may play an important role in As transient enhanced diffusion and agglomeration, especially at the early stage of postimplantation thermal annealing. We present the reaction paths and bonding mechanisms for the vacancy annihilation of Vn and AsmVn clusters by I-V recombination.
Atomic diffusion in liquid Ni, NiP, PdNiP, and PdNiCuP alloys
Authors: Chathoth S. Mavila , Meyer A. , Koza M. M. , Juranyi F.
Published: November 2004

We investigated the self-diffusion of Ni in liquid Ni, Ni80P20, Pd40Ni40P20, and Pd43Ni10Cu27P20 at temperatures up to 1795K with incoherent, quasielastic neutron scattering. Values of measured self-diffusion coefficients vary over the accessible temperature ranges as a function of composition only within 10%. Although mixing has a drastic effect on the liquidus temperature and the undercooling capabilities, a relation between these properties and the atomic diffusion in the liquid is not observed. Apparently, diffusive motion is governed by the packing fraction of the atoms, that is very similar in these dense liquids.
Effect of growth temperature on morphology, structure and luminescence of Eu-doped GaN thin films
Authors: Liu Q. L. , Bando Y. , Xu F. F. , Tang C. C.
Published: November 2004

The effect of growth temperature on morphology, structure, and photoluminescence (PL) of Eu-doped GaN (GaN:Eu) films grown by magnetron sputtering, and the relationships of growth-temperature-structure-PL were investigated by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and PL. The films grown at room temperature (RT), 573 K, and 773 K are composed of random crystalline grains, c-oriented GaN nanorods with lots of stacking faults, and well-crystalline c-oriented GaN, respectively. The characteristic emission lines of the Eu3+ were observed in the PL spectra at room temperature for the 573-K-grown and 773-K-grown films, while no emission line for the RT-grown film. The PL intensity from the 773-K-grown film is much stronger than that from the 573-K-grown film.
Magnetic properties of crystalline La0.7Ca0.3MnO3 films including a nanoscale disordered phase
Authors: Prokhorov V. G. , Komashko V. A. , Svetchnikov V. L. , Lee Y. P. , Hyun Y. H. , Kim J. B.
Published: November 2004

The magnetic properties of amorphous, crystalline (with disordered inclusions) and perfectly crystalline La0.7Ca0.3MnO3 thin films have been investigated. It was shown that the amorphous film is a paramagnet with the effective magnetic moment of 4.2μB∕Mn ion. The crystalline film with nanoscale disordered inclusions demonstrates a superposition of the ferromagnetic (corresponding to the crystalline matrix) and the superparamagnetic (corresponding to the nanocrystalline disordered inclusions) contributions in the magnetization. The completely crystalline film undergoes only a ferromagnetic transition.
Probing electrical transport across oxide interfaces by noncontact atomic force microscopy
Authors: Shao Rui , Bonnell Dawn A.
Published: November 2004

An approach for determining surface potential based on noncontact atomic force microscopy (NC-AFM) has been used to acquire the potential profile of the grain boundary in a 24° 0.05wt% Nb-doped SrTiO3 bicrystal under lateral bias. The breakdown voltage of the grain boundary is found to be 1.2V. The current–voltage characteristics obtained from this surface potentiometry have been compared with standard four-point measurement. The exponential dependence of the current on voltage indicates a Schottky-type transport mechanism. In addition, we found that NC-AFM topography is affected by the nonuniform potential distribution across the boundary, and this effect is especially strong at large lateral biases, resulting in a spurious step feature, which implies that true topography of an inhomogeneous surface cannot be obtained without first nullifying electrostatic interaction between tip and sample.
Observation of a manganese acceptor level in ferromagnetic Ga1−xMnxN layers
Authors: Yoon I. T. , Kang T. W. , Jeong M. C. , Ham M. H. , Myoung J. M.
Published: November 2004

We have observed the high-temperature (T=300K) photoluminescence (PL) spectra from free to Mn-related acceptor pair transitions in Ga1−xMnxN layers (where x≈0.2%–0.6%) grown on sapphire (0001) substrates using the plasma-enhanced molecular-beam epitaxy technique. Luminescence from an Mn acceptor level in Ga1−xMnxN layer with a low Mn content was observed at around E=3.08eV in the PL spectra. When compared to the PL from undoped GaN, the excitation, temperature-dependent PL at E=3.08eV provides convincing evidence for a neutral Mn acceptor-bound hole character. The binding energy of the Mn acceptor-bound holes of E=330meV is in good agreement with an ionization energy of E=402meV obtained using effective mass theory of shallow impurity states for the hydrogen model. In addition, analysis of the PL intensities of an acceptor-bound hole in a Ga1−xMnxN layer with x≈0.6% gave an activation energy of E=310meV, which indicates that the acceptor-bound hole with a binding energy of E=310meV was dissociated due to thermal quenching.
Valence-band tunneling induced low frequency noise in ultrathin oxide (15Å) n-type metal-oxide-semiconductor field effect transistors
Authors: Wu J. W. , You J. W. , Ma H. C. , Cheng C. C. , Chang C. S. , Huang G. W. , Wang T.
Published: November 2004

Low frequency flicker noise in n-type metal-oxide-semiconductor field effect transistors (n-MOSFETs) with 15Å gate oxide is investigated. A noise generation mechanism resulting from valence band tunneling is proposed. In strong inversion condition, valence-band electron tunneling takes place and results in the splitting of electron and hole quasi-Fermi levels in the channel. The excess low frequency noise is attributed to electron and hole recombination at interface traps between the two quasi-Fermi levels. Random telegraph signal in a small area device is characterized to support our model.
Effects of poling, and implications for metastable phase behavior in barium strontium titanate thin film capacitors
Authors: Lookman A. , McAneney J. , Bowman R. M. , Gregg J. M. , Kut J. , Rios S. , Ruediger A. , Dawber M. , Scott J. F.
Published: November 2004

Barium strontium titanate (Ba0.5Sr0.5TiO3–BST) thin film capacitor structures were made using pulsed laser deposition, and their functional properties were monitored with varying temperature. It was found that poling at low temperature could induce distinct differences in the behavior of the dielectric constant and loss tangent, on heating. In relatively thick BST films (>∼650nm), poling the sample at 80K produced a change from a single broad anomaly to one in which three distinct anomalies could be observed. The temperatures of these anomalies (∼140, ∼200, and ∼260K) were close to those known to be associated with phase transitions in bulk. Monitoring changes in polarization loops with temperature confirmed the likelihood that the dielectric anomalies observed were indeed the result of phase transitions in the films. Unusually, though, when the films were poled at 150K, and then cooled to 80K prior to collection of dielectric data on heating, the dielectric anomaly around 140K was completely suppressed. The lack of a phase transition was confirmed by monitoring depolarization currents in the sample. It is suggested that poling has therefore allowed the phase state that existed at 150K to persist metastably down to 80K. For relatively thin BST films (<∼400nm), poling at 80K only induced two distinct anomalies in the dielectric response (at ∼200 and ∼290K). Nevertheless, poling-related metastability could again be observed: when the samples were poled at 250K and then cooled to 80K prior to data collection on heating, the anomaly at ∼200K was completely suppressed. These experiments suggest that metastable phase behavior could be commonplace in thin film ferroelectrics.
Finite-width waveguide and waveguide intersections for self-collimated beams in photonic crystals
Authors: Li Zhaofeng , Chen Haibo , Song Zhitang , Yang Fuhua , Feng Songlin
Published: November 2004

The effect of waveguide width on the propagation of self-collimated beams in photonic crystals is studied using the finite-difference time-domain method. It is shown that, to obtain good transmission, it would be better to keep the waveguide width above a minimum value. It is also shown that waveguide intersections based on the effect of self-collimated beams can provide high throughput and low cross talk simultaneously within a relatively wide bandwidth.
Diet intake and endurance performance in Kenyan runners
Authors: Christensen Dirk L
Published: November 2004

Training and competing at elite as well as sub-elite level requires an optimal functioning of the body. This review looks at the case of the Kenyan runners, who consume a relatively high-quality diet based on vegetable sources with maize and kidney beans as the staple foods. The diet is high in carbohydrate and total protein, but low to borderline in a few essential amino acids. The timing of diet intake – immediately after training sessions – is optimal for skeletal muscle glycogen resynthesis that is enhanced without the help of insulin up to 60 min after cessation of exercise. Whether the total energy intake of the Kenyan runners is adequate is debatable. However, chronic undernutrition is not possible for athletes who engage in daily high-quality and -quantity physical exercise throughout most of the year. It is suggested that Kenyan runners participate in well-controlled, laboratory studies to investigate the quality of local foods and performance, as well as possible physiological adaptation mechanisms among athletes with a high habitual energy turnover.
Incidence and Significance of Cardiac Troponin I Release in Severe Trauma Patients
Authors: Edouard Alain R. , Felten Marie-Louise , Hebert Jean-Louis , Cosson Claudine , Martin Laurent , Benhamou Dan
Published: November 2004

Background

The incidence and significance of troponin I release and its mechanism are unknown in severe trauma patients. The characteristics of this release were prospectively studied in such patients and correlated with presence of shock, existence of myocardial contusion, and outcome.

Methods

During a 24-month period, serial electrocardiogram recordings and troponin I measurements were performed in all trauma patients admitted at a surgical intensive care unit. The diagnosis of a significant myocardial contusion was made on electrocardiographic criteria. According to the time course of troponin I, three groups of patients were defined a priori: very transient (</= 12 h) and limited release (troponin I < 2 microg/l), transient (</= 36 h) and significant release (troponin I >/= 2 microg/l), and sustained (> 36 h) and significant release (troponin I > 2 microg/l). In the last group, coronary artery angiography was performed.

Results

The incidence of troponin I release was 12% (95% confidence interval [CI], 9.6-14.4%) in 728 patients. A significant myocardial contusion was found in 35 patients (5%; 95% CI, 3.4-6.6%) and may occur in the absence of chest trauma and without troponin I release. Sensitivity, specificity, and positive and negative predictive values of troponin I for the diagnosis of myocardial contusion were 63, 98, 40, and 98%, respectively. Troponin I release was observed in 54 early (> 48 h) survivors (7%; 95% CI, 5.6-9.6%) without preexisting coronary artery disease. A sustained and significant release of troponin I (17 patients) was frequently associated with chest trauma (82%) and constantly with electrocardiographic abnormalities. A coronary artery injury was found in 7 patients (2 major and 5 minor vascular injuries) (1% of the whole group; 95% CI, 0.4-2.0%). Mortality was similar in early survivors with (15%; 95% CI, 7-27%) or without (12%; 95% CI, 9-14%) troponin I release. The odds ratio for late mortality was 1.32 (95% CI, 0.61-2.85) in patients with troponin I release.

Conclusions

Serial electrocardiogram recordings and troponin I assessments may be proposed for initial screening in high-risk trauma patients to detect anatomical cardiac injuries through the time course of circulating protein. Troponin I release does not have a prognosis value in trauma patients.
Comparative Evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index® Monitor during Propofol–Remifentanil Anesthesia
Authors: Schmidt Gunter N. , Bischoff Petra , Standl Thomas , Hellstern Angelika , Teuber Olaf , Schulte am Esch Jochen
Published: November 2004

Background

Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index(R) monitor (BIS(R); Aspect Medical Systems, Newton, MA) during propofol-remifentanil anesthesia.

Methods

The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 microg/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 microg . kg(-1) . min(-1)) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability.

Results

SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate.

Conclusion

SE, RE, and BIS revealed similar information about the level of sedation and allowed the authors to distinguish between different steps of anesthesia. Both monitors provided useful additional information for the anesthesiologist.
Proper Shoulder Position for Subclavian Venipuncture
Authors: Kitagawa Norihito , Oda Mayuko , Totoki Tadahide , Miyazaki Noriaki , Nagasawa Ichiroh , Nakazono Takahiko , Tamai Tsutomu , Morimoto Masatoshi
Published: November 2004

Background

Although the Trendelenburg position and shoulder bracing are recommended for safe subclavian venipuncture, the optimal shoulder position remains unclear. The current study observed spatial relations between the subclavian vein and surrounding structures using multislice computed tomography to determine optimal shoulder position for safe subclavian venipuncture and then conducted a small follow-up clinical trial to confirm these findings.

Methods

Thoracic multislice computed tomography was performed for seven adult volunteers at three shoulder positions: elevated (up); neutral; and lowered caudally (down). Overlap and distance between the clavicle and the subclavian vein and the diameter of the subclavian vein were measured. Anatomical relations between the subclavian artery and vein were also observed. The success rate for subclavian venipuncture was then compared between the up and down shoulder positions in 30 patients.

Results

In the multislice computed tomography study, the mean overlap ratios between clavicle and subclavian vein in the up, neutral, and down positions were 33.5, 36.9, and 40.0%, respectively. Overlap increased with lower shoulder position (up < neutral < down; P < 0.05). The mean distances between the clavicle and the subclavian vein in the up, neutral, and down positions were 6.8, 5.0, and 3.6 mm, respectively. Again, distance decreased with lower shoulder position (up < neutral < down; P < 0.05). The diameter of the subclavian vein did not differ among the three shoulder positions. The success rate for subclavian venipuncture was significantly higher in the down position compared with the up position (P = 0.003).

Conclusions

Lowered shoulder position increases both overlap and proximity between the clavicle and the subclavian vein, producing a more constant relation between the clavicle and the subclavian vein, without affecting vein diameter. Proper use of a lowered shoulder position should thus increase the safety and reliability of subclavian venipuncture compared with other shoulder positions.
The Inhibitory Effects of Isoflurane on Protein Tyrosine Phosphorylation–modulated Contraction of Rat Aortic Smooth Muscle
Authors: Yu Jingui , Ogawa Koji , Tokinaga Yasuyuki , Mizumoto Kazuhiro , Kakutani Tetsuya , Hatano Yoshio
Published: November 2004

Background

Tyrosine kinase-catalyzed protein tyrosine phosphorylation plays an important role in initiating and modulating vascular smooth muscle contraction. The aim of the current study was to examine the effects of isoflurane on sodium orthovanadate (Na3VO4), a potent protein tyrosine phosphatase inhibitor-induced, tyrosine phosphorylation-mediated contraction of rat aortic smooth muscle.

Methods

The Na3VO4-induced contraction of rat aortic smooth muscle and tyrosine phosphorylation of proteins including phospholipase Cgamma-1 (PLCgamma-1) and p44/p42 mitogen-activated protein kinase (MAPK) were assessed in the presence of different concentrations of isoflurane, using isometric force measurement and Western blotting methods, respectively.

Results

Na3VO4 (10(-4) m) induced a gradually sustained contraction and significant increase in protein tyrosine phosphorylation of a set of substrates including PLCgamma-1 and p42MAPK, all of which were markedly inhibited by genistein (5 x 10(-5) m), a tyrosine kinase inhibitor. Isoflurane (1.2-3.5%) dose-dependently depressed the Na3VO4-induced contraction (P < 0.05-0.005; n = 8). Isoflurane also attenuated the total density of the Na3VO4-induced, tyrosine-phosphorylated substrate bands and the density of tyrosine-phosphorylated PLCgamma-1 band and p42MAPK band (P < 0.05-0.005; n = 4) in a concentration-dependent manner.

Conclusion

The findings of the current study, that isoflurane dose-dependently inhibits both the Na3VO4-stimulated contraction and tyrosine phosphorylation of a set of proteins including PLCgamma-1 and p42MAPK in rat aortic smooth muscle, suggest that isoflurane depresses protein tyrosine phosphorylation-modulated contraction of vascular smooth muscle, especially that mediated by the tyrosine-phosphorylated PLCgamma-1 and MAPK signaling pathways.
Maternal Insufflation during the Second Trimester Equivalent Produces Hypercapnia, Acidosis, and Prolonged Hypoxia in Fetal Sheep
Authors: Uemura Kenichiro , McClaine Rebecca J. , de la Fuente Sebastian G. , Manson Roberto J. , Campbell Kurt A. , McClaine Deborah J. , White William D. , Stamler Jonathan S. , Eubanks W Steve , Reynolds James D.
Published: November 2004

Background

Anecdotal reports suggest that the second trimester is the safest time to conduct a laparoscopic procedure on a pregnant patient, but this supposition has not been tested empirically.

Methods

Previously instrumented preterm sheep (total n = 8) at gestational day 90 (term, 145 days) were anesthetized and then insufflated with carbon dioxide for 60 min at a pressure of 15 mmHg. Cardiovascular parameters were continuously recorded while blood gas status was determined before and at 15-min intervals during and up to 2 h after insufflation.

Results

Insufflation produced minimal maternal blood gas or cardiovascular changes except for a significant reduction in uterine blood flow. The decrease in perfusion increased fetal arterial blood partial pressure of carbon dioxide and decreased fetal pH, oxygen saturation, and oxygen content; there was also progressive fetal hypotension and bradycardia. After manually deflating the ewe, uterine blood flow returned to normal, and the fetal partial pressure of carbon dioxide and pH changes resolved within 1 h. However, fetal oxygen saturation and content remained depressed, and fetal cardiovascular status continued to decline during the 2-h postinsufflation monitoring period.

Conclusion

Previous studies with near-term sheep determined that carbon dioxide pneumoperitoneum produces respiratory acidosis but does not decrease fetal oxygenation. In contrast, the current findings indicate that in the preterm fetus, insufflation-induced hypercapnia and acidosis are accompanied by prolonged fetal hypoxia and cardiovascular depression. This result suggests that additional work should be conducted to confirm the presumed safety of conducting minimally invasive procedures during the second trimester.