bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of PKC in the attenuation of the cGMP‐mediated relaxation of skinned resistance artery smooth muscle seen in glyceryl‐trinitrate‐tolerant rabbit
Authors: Nakano Youichirou , Kusama Nobuyoshi , Kajikuri Junko , Suzuki Yoshikatsu , Kanmura Yuichi , Itoh Takeo
Published: February 2004

We examined whether 10 days’ in vivo treatment with glyceryl trinitrate (GTN) might reduce cGMP‐induced relaxation in the smooth muscle of rabbit mesenteric resistance arteries and, if so, whether protein kinase C (PKC) plays a role in this downregulation.

The relaxation responses to GTN and the nitric oxide donor NOC‐7 were significantly reduced in endothelium‐denuded strips from GTN‐treated rabbits. In β‐escin‐skinned smooth muscle, the ability of 8‐bromoguanosine 3′,5′ cyclic monophosphate (8‐Br‐cGMP, a phosphodiesterase‐resistant cGMP analogue) to relax the contraction induced by 0.3 μM Ca2+ was significantly reduced in GTN‐treated rabbits.

In β‐escin‐skinned smooth muscle, an inhibitor of conventional and/or novel PKCs, GF109203X (0.6 μM), inhibited the Ca2+‐induced contraction and enhanced the 8‐Br‐cGMP‐induced relaxation. However, since the relaxing ability of 8‐Br‐cGMP was found to be unchanged by GF109203X when contractions were amplitude‐matched (0.2 μM Ca2+ alone vs 0.3 μM Ca2++GF109203X), the increase in the 8‐Br‐cGMP‐response seen with GF109203X was probably due to its inhibitory action on the Ca2+‐induced contraction. Furthermore, although the PKC activator phorbol 12,13‐dibutyrate (PDBu, 0.1 μM) decreased the 8‐Br‐cGMP‐induced relaxation of the Ca2+ (0.3 μM) contraction, this was probably due to its enhancement of the Ca2+‐induced contraction since no such effect of PDBu was seen when the Ca2+‐induced contractions were amplitude‐matched (0.2 μM Ca2++PDBu vs 0.3 μM Ca2+ alone).

These results suggest that the relaxing response to cGMP is reduced in the smooth muscle of mesenteric resistance arteries in GTN‐treated rabbits but that conventional and/or novel PKCs do not play a major role in maintaining this downregulation.

British Journal of Pharmacology (2004) 141, 391–398. doi:10.1038/sj.bjp.0705625
Iloprost inhibits superoxide formation and gp91phox expression induced by the thromboxane A2 analogue U46619, 8‐isoprostane F2α, prostaglandin F2α, cytokines and endotoxin in the pig pulmonary artery
Authors: Muzaffar Saima , Shukla Nilima , Lobo Clinton , Angelini Gianni D , Jeremy Jamie Y
Published: February 2004

Since the roles of thromboxane A2 (TXA2), prostacyclin (PGI2) and 8‐isoprostane F2α in mediating vascular O2•− formation and its relation to adult respiratory distress syndrome (ARDS) is unknown, the effects of these eicosanoids on the expression of gp91phox (catalytic subunit of NADPH oxidase) and O2•− release from cultured pig pulmonary artery (PA) segments, PA vascular smooth muscle cells (PAVSMCs) and PA endothelial cells (PAECs) were investigated.

PA segments, PAVSMCs and PAECs were incubated with the TXA2 analogue, U46619, (±LPS, tumour necrosing factor‐alpha (TNF‐α) or IL‐1α), 8‐isoprostane F2α and±iloprost (a stable PGI2 analogue) for 16 h. The formation of superoxide dismutase‐inhibitable O2•− was then measured spectrophotometrically and gp91phox expression assessed using Western blotting. In parallel experiments, whole PA segments were treated with LPS, TNF‐α and IL‐α after which time TXA2, PGI2, PGF2α and 8‐isoprostane F2α formation was measured using enzyme‐linked immunoassays.

U46619, PGF2α and 8‐isoprostane F2α promoted the formation of O2•− in PA segments, PAVSMCs and PAECs, an effect inhibited by diphenyleneiodonium and apocynin (both NADPH oxidase inhibitors) and upregulated the expression of gp91phox in PAECs and PAVSMCs. These effects were augmented by LPS, TNF‐α and IL‐1α but inhibited by iloprost. Under identical incubation conditions, IL‐1α, LPS and TNF‐α all induced an increase in the formation of TXA2, PGF2α and 8‐isoprostane F2α but reduced the concomitant formation of PGI2.

These data demonstrate that LPS and cytokines influence the relative balance of TXA2, PGI2, PGF2α and 8‐isoprostane F2α in pig PA, which in turn alter NADPH oxidase expression and O2•− formation. These novel findings have implications in devising effective strategies for treating ARDS.

British Journal of Pharmacology (2004) 141, 488–496. doi:10.1038/sj.bjp.0705626
Characterization of an anandamide degradation system in prostate epithelial PC‐3 cells: synthesis of new transporter inhibitors as tools for this study
Authors: Ruiz‐Llorente Lidia , Ortega‐Gutiérrez Silvia , Viso Alma , Sánchez María G , Sánchez Ana M , Fernández Carlos , Ramos José A , Hillard Cecilia , Lasunción Miguel A , López‐Rodríguez María L , Díaz‐Laviada Inés
Published: February 2004

The response of anandamide is terminated by a carrier‐mediated transport followed by degradation catalyzed by the cloned enzyme fatty acid amidohydrolase (FAAH). In this study, we provide biochemical data showing an anandamide uptake process and the expression of FAAH in human prostate.

Anandamide was accumulated in PC‐3 cells by a saturable and temperature‐dependent process. Kinetic studies of anandamide uptake, determined in the presence of cannabinoid and vanilloid antagonists, revealed apparent parameters of KM=4.7±0.2 μM and Vmax=3.3±0.3 pmol min−1 (106 cells)−1.

The accumulation of anandamide was moderately inhibited by previously characterized anandamide transporter inhibitors (AM404, UCM707 and VDM11) but was unaffected by inhibitors of other lipid transport systems (phloretin or verapamil) and moderately affected by the FAAH inhibitor methyl arachidonyl fluorophosphonate.

The presence of FAAH in human prostate epithelial PC‐3 cells was confirmed by analyzing its expression by Western blot and measuring FAAH activity.

To further study the structural requirements of the putative carrier, we synthesized a series of structurally different compounds 1–8 and evaluated their capacity as uptake inhibitors. They showed different inhibitory capacity in PC‐3 cells, with (9Z,12Z)‐N‐(fur‐3‐ylmethyl)octadeca‐9,12‐dienamide (4, UCM119) being the most efficacious, with maximal inhibition and IC50 values of 49% and 11.3±0.5 μM, respectively.

In conclusion, PC‐3 cells possess a complete inactivation system for anandamide formed by an uptake process and the enzyme FAAH. These results suggest a possible physiological function of anandamide in the prostate, reinforcing the role of endocannabinoid system as a neuroendocrine modulator.

British Journal of Pharmacology (2004) 141, 457–467. doi:10.1038/sj.bjp.0705628
Impact of treatment with melatonin on cerebral circulation in old rats
Authors: Dupuis François , Régrigny Olivier , Atkinson Jeffrey , Limiñana Patrick , Delagrange Philippe , Scalbert Elizabeth , Chillon Jean‐Marc
Published: February 2004

Melatonin deprival in young rats induces alterations in cerebral arteriolar wall similar to those observed during aging: atrophy and a decrease in distensibility. In this study, we examined the effects of melatonin treatment on cerebral arteriolar structure and distensibility and on the lower limit of cerebral blood flow autoregulation (LLCBF) in old rats.

We measured cerebral blood flow (arbitrary unit, laser Doppler, open skull preparation) prior to and during stepwise hypotension (SH) in adult (12/13 months) and old (24/25 months) IcoWI and WAG/Rij male rats. Old rats were untreated or treated for 3 months with melatonin (0.39 (IcoWi) and 0.44 (Wag/Rij) mg kg−1 day−1, drinking water). Stress–strain relationships were determined using cross‐sectional area (CSA, μm2, histometry) and values of arteriolar internal diameter (μm) obtained during a second SH following arteriolar deactivation (EDTA, 67 mmol l−1).

Aging induced (a) atrophy of the arteriolar wall in IcoWI (616±20 vs 500±27 μm2, P<0.05) but not in WAG/Rij rats (328±25 vs 341±20 μm2), (b) a decrease in arteriolar wall distensibility and (c) an increase in the LLCBF in both strains (67±10 mmHg in 12‐month‐old vs 95±6 mmHg in 24‐month‐old IcoWi, P<0.05 and 53±2 mmHg in 13‐month‐old vs 67±6 mmHg in 25‐month‐old WAG/Rij).

Melatonin treatment induced in IcoWI and WAG/Rij rats (a) hypertrophy of the arteriolar wall (643±34 and 435±25 μm2, respectively), (b) an increase in arteriolar wall distensibility and (c) a decrease in the LLCBF (64±6 and 45±4 mmHg, respectively).

Melatonin treatment of old rats induced hypertrophy of the arteriolar wall, prevented the age‐linked decrease in cerebral arteriolar distensibility and decreased the LLCBF.

British Journal of Pharmacology (2004) 141, 399–406. doi:10.1038/sj.bjp.0705629
Na+/H+ exchange inhibition attenuates left ventricular remodeling and preserves systolic function in pressure‐overloaded hearts
Authors: Marano Giuseppe , Vergari Alessandro , Catalano Liviana , Gaudi Simona , Palazzesi Sergio , Musumeci Marco , Stati Tonino , Ferrari Alberto U
Published: February 2004

Cardiac hypertrophy is a homeostatic response to elevated afterload. Na+/H+ exchanger (NHE) inhibition reduces the hypertrophic response in animal models of left ventricular hypertrophy (LVH) and myocardial infarction. We examined the effect of chronic treatment with cariporide, a selective inhibitor of Na+/H+ exchanger isoform 1 (NHE‐1), on left ventricular (LV) systolic and diastolic function under pressure overload conditions.

Male CD‐1 mice were randomized to receive either a control diet or an identical diet supplemented with 6000 p.p.m. of cariporide. Cardiac pressure overload was induced by thoracic aortic banding. LV dimension and systolic and diastolic function were assessed in sham and banded mice by echocardiography and cardiac catheterization 2 and 5 weeks after surgery. Histological analysis was also performed.

After 2 weeks of pressure overload, the vehicle‐treated banded mice (Veh‐Bd) had enhanced normalized LV weight (about +50%) and normal chamber size and function, whereas cariporide‐treated banded mice (Car‐Bd) showed a preserved contractility and systolic function despite a marked attenuation of LVH. Diastolic function did not differ significantly among groups. After 5 weeks, the Veh‐Bd developed LV chamber enlargement and systolic dysfunction as evidenced by a 16% increase in LV end‐diastolic diameter, a 36% decrease in myocardial contractility, and a 26% reduction in percent fractional shortening. In contrast, Car‐Bd showed an attenuated increase in LV mass, normal chamber size, and a maintained systolic function. A distinct histological feature was that in banded mice, cariporide attenuated the development of cardiomyocyte hypertrophy but not the attendant myocardial fibrosis.

In conclusion, the results of the present study indicate that (i) the hypertrophic response to pressure overload is dependent on NHE‐1 activity, and (ii) at the 5‐week stage, banding‐induced deterioration of LV performance is prevented by NHE‐1 inhibition.

British Journal of Pharmacology (2004) 141, 526–532. doi:10.1038/sj.bjp.0705631
Brain‐derived neurotrophic factor (BDNF) contributes to neuronal dysfunction in a model of allergic airway inflammation
Authors: Braun Armin , Lommatzsch Marek , Neuhaus‐Steinmetz Ulrich , Quarcoo David , Glaab Thomas , McGregor Gerard P , Fischer Axel , Renz Harald
Published: February 2004

Brain‐derived neurotrophic factor (BDNF) is a candidate molecule for mediating functional neuronal changes in allergic bronchial asthma. Recently, enhanced production of BDNF during allergic airway inflammation caused by infiltrating T‐cells and macrophages as well as by resident airway epithelial cells has been described. It was the aim of this study to investigate the effect of enhanced BDNF levels on lung function and airway inflammation in a mouse model of allergic inflammation.

Ovalbumin‐sensitised BALB/c mice were challenged in two consecutive allergen challenges. Prior to the challenge, the mice were treated with either anti‐BDNF antibodies or isotype‐matched control antibodies. Airway responsiveness to methacholine, capsaicin and electric field stimulation, as well as airway inflammation and chronic airway obstruction 1 week after the last allergen challenge were assessed.

Anti‐BDNF blocked enhanced reactivity in response to capsaicin, but not airway smooth muscle hyper‐reactivity in vivo. Furthermore, persistent airway obstruction, as observed 1 week after the last allergen challenge, was to a large extent prevented by anti‐BDNF treatment. In vitro, BDNF and anti‐BDNF treatment had a profound effect on local neuronal hyper‐reactivity, as shown by electric field stimulation experiments. In contrast, neither BDNF nor anti‐BDNF treatment affected airway inflammation.

Our data indicate that development of allergen‐induced neuronal hyper‐reactivity in mice is partially mediated by BDNF.

British Journal of Pharmacology (2004) 141, 431–440. doi:10.1038/sj.bjp.0705638
Epoxyeicosatrienoic acids mediate adenosine‐induced vasodilation in rat preglomerular microvessels (PGMV) via A2A receptors
Authors: Cheng M K , Doumad A B , Jiang H , Falck J R , McGiff J C , Carroll M A
Published: February 2004

Activation of rat adenosine 2A receptors (A2A R) dilates preglomerular microvessels (PGMV), an effect mediated by epoxyeicosatrienoic acids (EETs).

Incubation of PGMV with a selective A2A R agonist, 2‐p‐(2‐carboxyethyl) phenethylamino‐5′‐N‐ethylcarboxamidoadenosine (CGS 21680; 100 μM), increased isolated PGMV EET levels to 7.57±1.53 ng mg−1 protein from 1.06±0.22 ng mg−1 protein in controls (P<0.05), without affecting hydroxyeicosatetraenoic acid (HETE) levels (10.8±0.69 vs 11.02±0.74 ng mg−1 protein).

CGS 21680‐stimulated EETs was abolished by preincubation with an A2A R antagonist, 4‐(2‐[7‐amino‐2‐(2‐furyl)[1,2,4]triazolo[2,3‐a][1,3,5]triazin‐5‐ylamino]ethyl)phenol (ZM241385) (100 μM). A selective epoxygenase inhibitor, methylsulfonyl‐propargyloxyphenylhexanamide (MS‐PPOH; 12 μM) prevented CGS 21680‐induced increase in EETs, indicating inhibition of de novo synthesis of EETs.

In pressurized (80 mmHg) renal arcuate arteries (110–130 μm) preconstricted with phenylephrine (20 nM), superfusion with CGS 21680 (0.01–10 μM) increased the internal diameter (i.d.) concentration‐dependently; vasodilation was independent of nitric oxide and cyclooxygenase activity. CGS 21680 (10 μM) increased i.d. by 32±6 μm; vasodilation was prevented by inhibition of EET synthesis with MS‐PPOH.

Addition of 3 nM 5,6‐EET, 8,9‐EET and 11,12‐EET increased i.d. by 53±9, 17±4 and 53±5 μm, respectively, whereas 14,15‐EET was inactive. The responses to 5,6‐EET were, however, significantly inhibited by indomethacin.

We conclude that 11,12‐EET is the likely mediator of A2A R‐induced dilation of rat PGMV. Activation of A2A R coupled to de novo EET stimulation may represent an important mechanism in regulating preglomerular microvascular tone.

British Journal of Pharmacology (2004) 141, 441–448. doi:10.1038/sj.bjp.0705640
Evidence for high stability against water corrosion of NdBa2Cu3O7±δ relative to YBa2Cu3O7−δ and EuBa2Cu3O7−δ
Authors: Schougaard Steen B. , Ali Mehnaaz F. , McDevitt John T.
Published: February 2004

While prior studies have revealed enhanced stability of Y0.6Ca0.4Ba1.6La0.4Cu3O7−δ relative to YBa2Cu3O7−δ, this stabilization was brought about only at the expense of lower transition temperatures (TC∼80 versus 92 K). Similar prior attempts to optimize simultaneously both superconductivity properties and chemical stability with substitution only at the rare-earth site in REBa2Cu3O7 (RE=Y, Eu, Gd, etc.) resulted in little alteration of the observed reactivity/processability characteristics. In this letter, the corrosion reactivity of REBa2Cu3O7 (RE=Y, Eu, Nd) and Y0.6Ca0.4Ba1.6La0.4Cu3O7−δ are examined. An unusually strong stabilization was noted for NdBa2Cu3O7±δ (TC,onset⩾92 K). This corrosion behavior for the RE=Nd phase is rationalized in terms of a structural model.
Characteristics of single crystal “thin film” capacitor structures made using a focused ion beam microscope
Authors: Saad M. M. , Bowman R. M. , Gregg J. M.
Published: February 2004

The focused ion beam microscope was used to isolate thin parallel-sided lamellae from single crystals of BaTiO3 and SrTiO3. Damage and ion-implantation on the faces of the lamellae were observed, but could be removed by thermal annealing. A series of lamellae ranging in thickness from ∼660 to ∼300 nm were made from a SrTiO3 single crystal, and after thermal annealing, gold electrodes were deposited on either side to form parallel-plate capacitor structures. The room temperature functional properties of these single crystal “thin film” capacitors were investigated. Although space-charge artifacts dominated the low frequency response, above 10 kHz, examination of the change in capacitance as a function of lamellar thickness allowed the room temperature relative dielectric constant to be meaningfully extracted. This was found to be ∼300, as is the case in bulk. For these single crystal lamellae there was therefore no evidence of a collapse in dielectric constant associated with thin film dimensions.
Highly efficient organic electrophosphorescent light-emitting diodes with a reduced quantum efficiency roll off at large current densities
Authors: Cocchi M. , Fattori V. , Virgili D. , Sabatini C. , Di Marco P. , Maestri M. , Kalinowski J.
Published: February 2004

High efficiency electrophosphorescence (EPH) in organic light-emitting devices was achieved employing a cyclometallated platinum [Pt(II)]-complexes-doped blend of N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′ diamine and bisphenol-A-polycarbonate as the emitting layer. Using bis-[2-(5-trimethylsilanyl-thiophen-2-yl)-pyridine] Pt(II) [Pt(thpy-SiMe3)] as a phosphorescent dopant, a maximum EPH external quantum efficiency of 11.5±0.5% photons/carrier was achieved with a three-fold lower roll-off factor at increasing current density, compared with commonly used Pt-based dye 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphine platinum (II) (PtOEP). The emission spectrum of the device peaking at ≅590 nm shifts the chromaticity coordinates toward the orange relative to the PtOEP-based devices.
Anomalous relationship between hardness and wear properties of a superelastic nickel–titanium alloy
Authors: Qian Linmao , Xiao Xudong , Sun Qingping , Yu Tongxi
Published: February 2004

We have studied the behavior of microwear and hardness of a superelastic nickel–titanium alloy using a triboindenter at various temperatures. Wear resistance was found to anomalously decrease with an increase in hardness. The observations are analyzed based on simple contact theory which suggests that the increase of hardness with the temperature is mainly due to an increase in phase transition stress, while the decrease of wear resistance with the temperature is due to an increase of the austenite elastic modulus and a decrease of the amount of phase transition that can be recovered.
Transition from partial to full depletion in silicon-on-insulator transistors: Impact of channel length
Authors: Allibert F. , Pretet J. , Pananakakis G. , Cristoloveanu S.
Published: February 2004

In short-channel silicon-on-insulator metal–oxide–semiconductor field-effect transistors, the condition for full depletion involves not only the body thickness and doping but also the channel length. The proximity of source and drain junctions reduces the apparent doping seen from the gate, which makes full depletion easier. Therefore, a transistor designed as partially depleted can behave as fully depleted. A simple analytical model for the length-doping transformation is proposed and validated by numerical simulations.
Elastic strain relaxation in free-standing SiGe/Si structures
Authors: Mooney P. M. , Cohen G. M. , Chu J. O. , Murray C. E.
Published: February 2004

We have investigated elastic strain relaxation, i.e., strain relaxation without the introduction of dislocations or other defects, in free-standing SiGe/Si structures. We fabricated free-standing Si layers supported at a single point by an SiO2 pedestal and subsequently grew an epitaxial SiGe layer. The measured strain relaxation of the SiGe layer agrees well with that calculated using a force-balance model for strain sharing between the SiGe and strained Si layers. We report strained Si layers with biaxial tensile strain equal to 0.007 and 0.012.
Syntactic bulk metallic glass foam
Authors: Brothers A. H. , Dunand D. C.
Published: February 2004

An amorphous metal foam with a bulk density of 3.4 g/cm3 is created by low-pressure melt infiltration of the bulk metallic glass-forming alloy Zr57Nb5Cu15.4Ni12.6Al10 into a bed of hollow carbon microspheres, followed by rapid quenching. The foam consists of a glassy metallic matrix containing ∼60 vol. % of homogenously distributed carbon microspheres, 25–50 μm in diameter, with small amounts of ZrC at the interface. An amorphous foam with 5 mm diameter showed no measurable loss in thermal stability as compared to the amorphous alloy in bulk form.
Voltage controlled metamaterial
Authors: Reynet O. , Acher O.
Published: February 2004

A tunable metamaterial based on conducting coils loaded by an electronic circuit containing a varicap diode has been demonstrated. The agility exceeds one octave inside the 100–500 MHz range. Permeability levels are significantly increased when the loop is loaded by a proper magnetic material. A model gives a good desription of the observed permeability spectra.
Effect of crystallinity on the transport properties of Nd0.67Sr0.33MnO3 thin films
Authors: Wang H. , Zhang X. , Hundley M. F. , Thompson J. D. , Gibbons B. J. , Lin Y. , Arendt P. N. , Foltyn S. R. , Jia Q. X. , MacManus-Driscoll J. L.
Published: February 2004

Highly crystalline Nd0.67Sr0.33MnO3 (NSMO) thin films were grown on (001) LaAlO3 (LAO) substrates using pulsed-laser deposition. By studying the microstructural properties of NSMO using x-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution TEM, we have found that high degree crystallinity leads to improved transport properties such as smaller resistivities at both peak and room temperatures. A peak temperature of 187 K has been observed from a resistivity-temperature measurement, and around 200 K from a magnetization measurement.
Ultralow-threshold erbium-implanted toroidal microlaser on silicon
Authors: Polman A. , Min B. , Kalkman J. , Kippenberg T. J. , Vahala K. J.
Published: February 2004

We present an erbium-doped microlaser on silicon operating at a wavelength of 1.5 μm that operates at a launched pump threshold as low as 4.5 μW. The 40 μm diameter toroidal microresonator is made using a combination of erbium ion implantation, photolithography, wet and dry etching, and laser annealing, using a thermally grown SiO2 film on a Si substrate as a starting material. The microlaser, doped with an average Er concentration of 2×1019 cm−3, is pumped at 1480 nm using an evanescently coupled tapered optical fiber. Cavity quality factors as high as 3.9×107 are achieved, corresponding to a modal loss of 0.007 dB/cm, and single-mode lasing is observed.
Electrical characterization of individual carbon nanotubes grown in nanoporous anodic alumina templates
Authors: Jang Wan Young , Kulkarni N. N. , Shih C. K. , Yao Zhen
Published: February 2004

We report electrical transport measurements of individual carbon nanotubes grown catalytically in a nanoporous anodic aluminum oxide template by thermal chemical vapor deposition of acetylene. The four-terminal resistance at room temperature scales linearly with the nanotube length indicating diffusive nature of transport. The conductance shows an exp[(−1/T)1/3] dependence on temperature T, suggesting that two-dimensional variable-range hopping is the dominant conduction mechanism. The maximum current density carried by these nanotubes is on the order of 106 A/cm2.
Polysulfone as an electro-optic polymer host material
Authors: Garner Sean M. , Cites Jeffrey S. , He Mingqian , Wang Jianguo
Published: February 2004

The practicality of using polysulfone as a host material for electro-optic polymer devices is demonstrated. For loadings of 15–25 weight %, r33 values of 53–55 pm/V were obtained at λ=1.06 μm. This corresponds to chromophore alignment efficiencies of up to 27%. Also, Mach–Zehnder devices demonstrated the implementation of a polysulfone host with a Vπ of 6.9 v, optical loss of 1.8 dB/cm, and thermal stability >100 °C.
Efficiency enhancement of Cu(In,Ga)Se2 solar cells due to post-deposition Na incorporation
Authors: Rudmann D. , da Cunha A. F. , Kaelin M. , Kurdesau F. , Zogg H. , Tiwari A. N. , Bilger G.
Published: February 2004

Cu(In,Ga)Se 2 (CIGS) absorber layers for thin-film solar cells were grown without sodium. Na was diffused into some of the absorbers after growth, which led to strongly improved device performance compared with Na-free cells. Efficiencies of 13.3% and 14.4% were achieved at substrate temperatures as low as 400 and 450 °C, respectively. With the post-deposition treatment, the effects of Na on CIGS growth are excluded, and most of the Na is expected to reside at grain boundaries. The dominating cause for Na-induced device improvements might be passivation of grain boundaries.
Derivation of nonlinear inductive coefficients from mutual inductance measurements of superconducting thin films
Authors: Claassen J. H.
Published: February 2004

A mutual inductance setup consisting of coils on opposite sides of a superconducting film is a well-known means to determine the penetration depth λ. Recently, it was shown that the same apparatus may be used to measure a nonlinear dependence of the form λ2(J)=λ02[1+(J/J0)2], where J is the current density and J0 characterizes the scale of nonlinear response. In this letter we calculate the nonlinear coupling between coils produced by this dependence. The calculation was done for a simplified geometry that retains the essential physics of the actual setup used in experiments, and allows quantitative evaluation of J0 within a fudge factor close to unity.
Room-temperature single nanoribbon lasers
Authors: Zapien J. A. , Jiang Y. , Meng X. M. , Chen W. , Au F. C. K. , Lifshitz Y. , Lee S. T.
Published: February 2004

Using a single nano-object measurement methodology that enables the correlation between size/morphology/structure and photoluminescence (PL) characteristics, we show that nanoribbons are an excellent model system to study single nano-objects. In particular, we measure the PL characteristics of optically pumped individual single-crystal zinc–sulfide nanoribbons. Small collection angle measurements show that nanoribbons form excellent optical cavities and gain medium with high (full width at half maximum<0.1 nm) lasing modes free of PL background even for a low pumping power density of 9 kW/cm2. Large collection angles add a broad PL component and obscure the correct high-quality lasing of the nanowires/nanoribbons.
Electroluminescent properties of erbium-doped III–N light-emitting diodes
Authors: Zavada J. M. , Jin S. X. , Nepal N. , Lin J. Y. , Jiang H. X. , Chow P. , Hertog B.
Published: February 2004

We report on the synthesis of Er-doped III–N double heterostructure light-emitting diodes (LEDs) and their electroluminescence (EL) properties. The device structures were grown through a combination of metalorganic chemical vapor deposition (MOCVD) and molecular-beam epitaxy (MBE) on c-plane sapphire substrates. The AlGaN layers, with an Al concentration of ∼12%, were prepared by MOCVD and doped with Si or Mg to achieve n- and p-type conductivity, respectively. The Er+O-doped GaN active region was grown by MBE and had a thickness of 50 nm. The Er concentration was estimated to be ∼1018 cm−3. The multilayer n-AlGaN/GaN:Er/p-AlGaN structures were processed into LEDs using standard etching and contacting methods. Several different LEDs were produced and EL spectra were recorded with both forward and reverse bias conditions. Typically, the EL under reverse bias was five to ten times more intense than that under forward bias. The LEDs displayed a number of narrow emission lines representative of the GaN:Er system (green: 539 nm, 559 nm; infrared: 1000 nm, 1530 nm). While some current crowding was observed, green emission was visible under ambient room conditions at 300 K. At cryogenic temperatures, the emission lines increased in intensity and had a narrower linewidth. EL spectra were recorded down to 10 K and the L-I characteristics were systematically measured. The power output of the brightest LEDs was approximately 2.5 W/m2 at 300 K.
Ultrafast intersubband relaxation and nonlinear susceptibility at 1.55 μm in GaN/AlN multiple-quantum wells
Authors: Hamazaki J. , Matsui S. , Kunugita H. , Ema K. , Kanazawa H. , Tachibana T. , Kikuchi A. , Kishino K.
Published: February 2004

Using a degenerate pump–probe technique on the Brewster configuration at room temperature, we investigate the dynamics of the intersubband transition in GaN/AlN multiple-quantum wells. The relaxation dynamics is found to consist of ultrafast (∼140 fs) and slower (∼1.3 ps) components. We estimate the third-order susceptibility for the Brewster configuration to be ∼5.5×10−18 m2/V2, which indicates that its value becomes ∼2.2×10−16 m2/V2 when a light beam is parallel to the well.
Electrospinning of continuous aligned polymer fibers
Authors: Sundaray Bibekananda , Subramanian V. , Natarajan T. S. , Xiang Rong-Zheng , Chang Chia-Cheng , Fann Wun-Shain
Published: February 2004

Electrospinning is a technique employed for preparing polymer fibers having diameters in the range of 10 μm–10 nm using high electrostatic field. In this letter, we report the formation of aligned polymer fibers, several centimeters in length, with separation between the fibers in the range of 5–100 μm. Achieving alignment is an important step toward the exploitation of these fibers in applications. We have employed about 4500 V and a separation distance of about 1–3 cm between the electrodes. Smaller distance between electrodes, we believe, provides better control on the formation of the fibers.
Comparison of the carrier induced refractive index, gain, and linewidth enhancement factor in quantum dot and quantum well lasers
Authors: Ukhanov A. A. , Stintz A. , Eliseev P. G. , Malloy K. J.
Published: February 2004

The spectral dependence of the modal gain and linewidth enhancement factor is measured in an InAs/GaInAs/AlGaAs/GaAs quantum dot (QD) laser and a GaInAs/AlGaAs/GaAs quantum well laser of the same design lacking only the quantum dots. The material differential gain and material differential carrier induced refractive index are found to be about three times smaller in the quantum dot laser than in the quantum well laser. The linewidth enhancement factor is smaller in the QD laser and exhibits considerably less dispersion.
High-contrast organic light-emitting diodes
Authors: Xie Z. Y. , Hung L. S.
Published: February 2004

High-contrast organic light-emitting diodes (OLEDs) with low-reflection cathode structures were constructed. The cathode structure consisted of a semitransparent cathode layer, a transparent phase-changing layer, and a highly reflective metal overlayer. When samarium (Sm), tris (8-quinolinolato) aluminum (Alq3), and Al were used as the cathode layer, phase-changing layer, and reflective layer, respectively, luminous reflectance of the resulting OLED was reduced from 81% to 2.7% as compared to a conventional OLED with a LiF/Al cathode. A further reduction to 0.9% was realized by replacing a multilayer of Alq3/Sm/Alq3 for the single phase-change layer of Alq3. In such a structure, the spectral reflectance was below 0.03 in the entire visible region and showed a weak dependence on incident angles of light. A contrast ratio of 250:1 can be achieved at a brightness of 100 cd/m2 under 140 lx of ambient-lighting. Device efficiencies of the high-contrast OLEDs were reduced, while their electrical characteristics were almost identical to that of the control device.
Nanoscale-twinning-induced strengthening in austenitic stainless steel thin films
Authors: Zhang X. , Misra A. , Wang H. , Nastasi M. , Embury J. D. , Mitchell T. E. , Hoagland R. G. , Hirth J. P.
Published: February 2004

Magnetron-sputter-deposited austenitic 330 stainless steel (330 SS) films, several microns thick, were found to have a hardness ∼6.5 GPa, about an order of magnitude higher than bulk 330 SS. High-resolution transmission electron microscopy revealed that sputtered 330 SS coatings are heavily twinned on {111} with nanometer scale twin spacing. Molecular dynamics simulations show that, in the nanometer regime where plasticity is controlled by the motion of single rather than pile-ups of dislocations, twin boundaries are very strong obstacles to slip. These observations provide a new perspective to producing ultrahigh strength monolithic metals by utilizing growth twins with nanometer-scale spacing.
Ultrafast intramolecular energy transfer in single conjugated polymer chains probed by polarized single chromophore spectroscopy
Authors: Müller J. G. , Lupton J. M. , Feldmann J. , Lemmer U. , Scherf U.
Published: February 2004

Single molecule spectroscopy of rigid-rod ladder-type conjugated polymers reveals individual chromophore units on a polymer chain, exhibiting fluorescence linewidths of less than 1 nm. Whereas the fluorescence from a single chromophore is fully linearly polarized at low temperatures, a number of excitation pathways and polarizations exist due to rapid intramolecular energy transfer to the emitting site. We propose that the slightly branched structure of the polymer results in neighboring molecular sites with orthogonal dipole orientations, enabling rapid polarization rotation. We demonstrate linearly polarized emission, which is independent of the excitation plane of polarization and may form the basis for molecular optical logic operations.
Impact of photoinitiators on the photopolymerization and the optical properties of inorganic–organic hybrid polymers
Authors: Houbertz R. , Domann G. , Schulz J. , Olsowski B. , Fröhlich L. , Kim W.-S.
Published: February 2004

Sol-gel synthesis allows one to produce inorganic–organic hybrid polymer materials which can be functionalized in order to tailor their physical and chemical properties. Besides, the resulting material properties are significantly influenced by further technological processing of the materials in thin film technology, i.e., the photochemical and thermal curing of the materials. In order to investigate the relationship between technological processing and material properties, a model system containing methacrylic groups as organically polymerizable units is chosen. The degree of conversion of the C=C double bond of the methacrylic group in dependence of the ultraviolet (UV) initiator concentration upon processing is characterized using Fourier-transform infrared spectroscopy. The data are correlated to measurements of the refractive indices at selected wavelengths.
Spatial and spectral behavior of the optical near field studied by a terahertz near-field spectrometer
Authors: Mair S. , Gompf B. , Dressel M.
Published: February 2004

We have developed a technique to obtain spectroscopic information in the optical near field. The spectrometer operates in the frequency range from 30 GHz to 1.5 THz using highly monochromatic and coherent radiation which can be continuously tuned. Small pinholes (λ/100–λ/10) in thin copper foils serve as near-field probes. For an accurate, fast, and contact-less control of the probe–sample distance a confocal microscope is employed. We experimentally test the diffraction theory of electromagnetic waves on subwavelength pinholes. Based on our findings we formulate requirements for near-field spectroscopy at THz frequencies.
AlGaN/GaN-based metal–oxide–semiconductor diode-based hydrogen gas sensor
Authors: Kang B. S. , Ren F. , Gila B. P. , Abernathy C. R. , Pearton S. J.
Published: February 2004

The characteristics of Sc2O3/AlGaN/GaN metal–oxide–semiconductor (MOS) diodes as hydrogen gas sensors are reported. At 25 °C, a change in forward current of ∼6 mA at a bias of 2 V was obtained in response to a change in ambient from pure N2 to 10% H2/90% N2. This is approximately double the change in forward current obtained in Pt/GaN Schottky diodes measured under the same conditions. The mechanism of the change in forward gate current appears to be formation of a dipole layer at the oxide/GaN interface that screens some of the piezo-induced channel charge. The MOS-diode response time is limited by the mass transport of gas into the test chamber and not by the diffusion of atomic hydrogen through the metal/oxide stack, even at 25 °C. These devices look promising for applications requiring sensitive, long-term stable detection of combustion gases.
Förster energy transfer in combinatorial arrays of selective doped organic light-emitting devices
Authors: Cheon K. O. , Shinar J.
Published: February 2004

Energy transfer in highly-efficient doped organic light-emitting devices (OLEDs) is described and discussed. The OLEDs include a hole transport layer (HTL) and an electron transport layer composed of an efficient blue emitter. A region of the HTL adjacent to the host blue-emitting layer was doped with an efficient guest red dye. The blue emitter-to-red dye energy transfer probability PHGη was determined by comparing the emission from the two fluorophores and its dependence on the applied field. PHGη decreases with increasing field, probably due to an increasing fraction of dye molecules which are positively charged, i.e., which trap a hole. It is also estimated that at fields as low as 0.4 MV/cm, ∼50% of the dye emission is due to trap emission rather than Förster energy transfer. The analysis yields a Förster energy transfer radius R0=33.5±3.5 Å.
The British and their use of the Web for health information and advice: a survey
Authors: Nicholas David , Huntington Paul , Gunter Barrie , Withey Richard , Russell Chris
Published: February 2004

In the UK, both anecdotal and research evidence points to ever greater and more sophisticated use of the Web to provide health information and advice. The study reported here adds to this research with an online survey of Internet users’ reported use of the Web to access information about health and their opinions about the advice that can be obtained there. Over a period of three weeks more than 1,300 people responded to an online questionnaire produced by The British Life and Internet Project; 81 per cent or 997 of the respondents were British. The prime purpose of the questionnaire was to obtain information on the characteristics of the users of health information Web sites, to obtain feedback regarding for what they used online health sites and what were the perceived outcomes associated with using online health information.
Making health information accessible to patients
Authors: Jones Ray
Published: February 2004

Many NHS policy documents state the need to make health information accessible to all. Accessibility comprises physical availability and personal retrievability. Touch‐screen public access kiosks have been available since the early 1990s and there is some evidence from a study of NHS Direct kiosks that they could improve physical access to health information. Most health centres have little space for longer use of computers by patients. Eventually home access to the Internet will be available to most people. In the meantime, computers based in public libraries offer potential to provide health information for patients referred by their GP. However, more thought is needed as to the format and content of the information. Information tailored using the patient’s medical record is preferred by patients and may enable patients to engage more social support. More evidence is needed from well‐designed studies to inform the debate.
The potential for using hospital bedside TV services in England to provide patients with access to health information
Authors: McWhirter Gavin
Published: February 2004

This article is a summary of a report which looks at the potential of using television sets at hospital bedsides to provide patients with access to health information. The report was jointly commissioned by The Department of Health (DoH) and National Health Service (NHS) Direct Online, and focused on what could be done using existing (or planned) Patient Power infrastructure. The latest generation of systems from all three of the main suppliers of bedside television service could provide access to health information in a variety of ways. A group meeting was held with key internal DoH and NHS stakeholders. Interviews were held with the main suppliers of bedside television services. Opinions were also taken from several academics specialising in Health Informatics, from a range of commercial health information providers and a wide range of NHS Trust representatives. Two areas where further research would be of use are looking at the opportunities around digital radio as a way of providing patients with health information, and looking at any particular issues that exist around communication with patients while they are in hospital.
The publication of cancer research papers in high impact journals
Authors: Lewison Grant
Published: February 2004

Examines a set of over 27,000 UK papers in cancer research in order to identify the individual factors that influence the impact category of the journals in which they are published, using multiple regression analysis. The most important independent variables that have a positive effect are the numbers of authors and funding bodies, the research level (from clinical to basic), and the presence of certain universities, or of the USA, in the address field. Inter‐lab co‐operation was shown to have a negative effect on journal impact category, as was international co‐authorship. It is because such partnerships usually involve more authors and funding for the research that they are perceived to lead to higher impact work. There is also a tendency for papers to be published in higher impact journals in later years, probably because of market forces, which means that such journals will tend to expand.
The strategic role of digital libraries: issues in e‐learning environments
Authors: Wang Mei‐Yu
Published: February 2004

This article describes research aimed at providing educational organizations with practical strategies for implementing e‐learning. While conducting the research, the role of digital libraries in e‐learning environments was recognized, and the core procedures for building a supporting, effective learning environment by means of the digital library were suggested. In addition, a number of relevant issues arising in the course of this research were addressed by means of focus‐group discussions.
Problems in the preservation of electronic records
Authors: Siew Lin Lim , Ramaiah Chennupati K. , Kuan Wal Pitt
Published: February 2004

Terms such as medium preservation and technology preservation are now widely used when discussing issues related to the preservation of electronic records. The advent of electronic information introduces new preservation requirements. Medium preservation has been addressed in discussions on environmental and handling concerns for tapes, magnetic disks, optical disks, and the like. Greater attention should instead be directed to the obsolescence of technologies. It is a challenge to imagine not only how to technically preserve electronic records indefinitely, but also how to choose what to preserve and how to guarantee the electronic record’s reliability and authenticity in the future. The combined problems of immense volume, unstable storage media, and obsolete hardware and software add up to some very tough problems, which have to be dealt with. Digital preservation is becoming a business issue. Not only are historians, librarians and archivists alarmed by the loss of cultural and government records due to a lack in digital preservation, but certain industries have also realised that they need to keep data longer and longer for regulatory or business reasons.
Information for rural development: challenge for Nigerian rural public libraries
Authors: Bini Okiy Rose
Published: February 2004

Nigeria is a developing country where the majority of the population live in rural areas. The majority of these rural dwellers are either non‐literate or semi‐literate. The need to involve them in the national development process cannot be overemphasized. This can be achieved through the identification of the information needs of rural dwellers and the provision of innovative rural public library services to improve their level of literacy and education and to enhance their ability to use practical information relevant to their daily lives.
Clumps and collection description in the information environment in the UK with particular reference to Scotland
Authors: Dunsire Gordon , Macgregor George
Published: February 2004

The role, potential and interaction of networked catalogues and collection‐level description have recently been given emphasis in order that efficient resource discovery mechanisms, and the effective organisation of such resources, be facilitated within the UK's developing JISC information environment (IE). This article describes the work of CC‐interop, a JISC project, and related projects that inform the development of the IE and its ability to instantiate the functional model of online resource discovery to which JISC aspires. The article reviews the evolution of Z39.50 virtual union catalogue services and collection description services that preceded CC‐interop. The paper also discusses how such work is informing regional information environments, with particular reference to Scotland, and reveals how such local arrangements will benefit the wider JISC IE.
A survey of the Arabian Gulf library automation marketplace
Authors: Khurshid Zahiruddin
Published: February 2004

Presents results of a survey of the Arabian Gulf region marketplace for library automation systems. The paper provides a market review and evaluates the vendors' standing and discusses the various criteria that underpin relative success or failure in this specific marketplace. The paper begins with a short history of library automation systems in the region and the changes arising in the mid‐1990s as major European and North American vendors began to recognise its potential as a territory for growth opportunities in sales and support services. A market share analysis section in which vendors' varying success in fulfilling key local requirements as well as more widely applicable criteria are analysed in relation to their marketplace success. The Horizon system from Dynix emerges as the clear market leader in the principal states of the Arabian Gulf region, due mainly to its strong Arabic and local support capabilities. Finally, two tables list the market share and the relative shares in responsibility between parent company and local vendor for each major system aspect.
Biomedical journal collaboration in London: development of the union database
Authors: Fisher Mark
Published: February 2004

During 2001‐2002 a union database of holdings of biomedical journals in a number of higher education and research institutes in London was created. The project was one of several funded through the British Library's Co‐operation and Partnership Programme. This paper describes the practical steps involved in designing the database (using Microsoft Access software), collecting the data and developing an appropriate Web‐based search interface. The technical and human problems involved in a collaborative project such as this are highlighted.
Using Macromedia Flash to create online information skills materials at Edinburgh University Library
Authors: Bains Simon , Jones Richard
Published: February 2004

Growth in electronic information services, pressure on staff resources and developments in the area of electronic learning have resulted in a need for online information skills delivery. Edinburgh University Library has developed some simple animated tutorials using Macromedia Flash to support use of a number of library services. The process of planning, creating and evaluating the modules is described, and the need to consider issues of accessibility, usability and pedagogy is emphasised. Technical aspects of design and documentation are considered. We conclude that it is important to consider the cost and time involved in even a modest exercise of this nature, but that the Flash software makes it very achievable, given an initial investment in development time and training.