bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential organ‐specific response to salt stress and water deficit in nodulated bean (Phaseolus vulgaris)
Authors: VERDOY D. , LUCAS M. M. , MANRIQUE E. , COVARRUBIAS A. A. , DE FELIPE M. R. , PUEYO J. J.
Published: May 2004

Nodulated bean plants were exposed to mild salt stress or water deficit in such a way that the nodule's nitrogen‐fixing activity was reduced to about 25–30% that of controls. Water‐deprived plants showed a slight decrease in the weight of the aerial part, whereas the photosynthetic parameters were not significantly affected. In contrast, salt‐stressed plants displayed a reversible decrease in the quantum yield of photosystem II photochemistry. Five water‐deficit responsive cDNA clones encoding one lipid transfer protein, two late‐embryogenesis abundant (LEA) proteins and two proline‐rich proteins (PRPs) showed different organ‐specific expression patterns depending on the kind of stress applied. PRPs and one LEA protein, PvLEA‐18, exhibited the highest expression in nodules. Anti‐PvLEA‐18 antibodies were used to immunolocalize the protein in the nodule. PvLEA‐18 was localized in the cytoplasm and nucleus of nodule cortex cells, and preferentially in cells of the vascular bundles, showing enhanced accumulation under water deficit. To our knowledge, this is the first time that a LEA protein has been identified in legume nodules.
Phase 2, Randomized, Dose-Ranging Study Evaluating the Safety and Efficacy of Anidulafungin in Invasive Candidiasis and Candidemia
Authors: Krause David S. , Reinhardt John , Vazquez Jose A. , Reboli Annette , Goldstein Beth P. , Wible Michele , Henkel Timothy
Published: May 2004

This study evaluated the safety and efficacy of anidulafungin, a novel echinocandin, in patients with invasive candidiasis, including candidemia. A total of 123 eligible patients were randomized to one of three intravenous regimens, 50, 75, or 100 mg once daily. Treatment continued for 2 weeks beyond resolution or improvement of signs and symptoms. The primary efficacy criterion was a successful global response rate (i.e., clinical and microbiological success) in the evaluable population at the follow-up (FU) visit, 2 weeks after end of therapy (EOT). One hundred twenty (120) patients received at least one dose of anidulafungin; 68 were evaluable. Review of adverse events and laboratory data indicated no dose response for safety parameters. Non-
albicans Candida
species accounted for approximately one-half of all isolates. Success rates at EOT were 84, 90, and 89% in the 50-, 75-, and 100-mg groups, respectively. At FU, the success rates were 72, 85, and 83%. Phase 3 studies of anidulafungin for the treatment of invasive candidiasis and candidemia are warranted.
Interaction of Antimycobacterial Drugs with the Anti-Mycobacterium aviumComplex Effects of Antimicrobial Effectors, Reactive Oxygen Intermediates, Reactive Nitrogen Intermediates, and Free Fatty Acids Produced by Macrophages
Authors: Sano Keisuke , Tomioka Haruaki , Sato Katsumasa , Sano Chiaki , Kawauchi Hideyuki , Cai Shanshan , Shimizu Toshiaki
Published: May 2004

The profiles of the interaction of antimycobacterial drugs with macrophage (MΦ) antimicrobial mechanisms have yet to be elucidated in detail. We examined the effects of various antimycobacterial drugs on the anti-Mycobacterium aviumcomplex (MAC) antimicrobial activity of reactive oxygen intermediates (ROIs), especially of an H2O2-halogen (H2O2-Fe2+-NaI)-mediated bactericidal system, reactive nitrogen intermediates (RNIs), and free fatty acids (FFAs), which are known as central antimicrobial effectors of host MΦs against mycobacterial pathogens. We have found that certain drugs, such as rifampin (RIF), rifabutin (RFB), isoniazid (INH), clofazimine (CLO), and some fluoroquinolones, strongly or moderately reduced the anti-MAC activity of the H2O2-Fe2+-NaI system, primarily by inhibiting the generation of hypohalite ions and in part by interfering with the halogenation reaction of bacterial cell components due to the H2O2-Fe2+-NaI system. This phenomenon is specific to the H2O2-Fe2+-NaI system, since these drugs did not reduce the anti-MAC activity of RNIs and FFAs. From the perspective of the chemotherapy of MAC infections, the present findings indicate an important possibility that certain antimycobacterial drugs, such as rifamycins (RIF and RFB), INH, CLO, and also some types of fluoroquinolones, may interfere with the ROI-mediated antimicrobial mechanisms of host MΦs against intracellular MAC organisms.
Subjective functional assessments and the return to competitive sport after anterior cruciate ligament reconstruction
Authors: Smith F W , Rosenlund E A , Aune A K , MacLean J A , Hillis S W
Published: May 2004

Objectives:To examine (a) return to competitive sport within 12 months of anterior cruciate ligament (ACL) reconstruction, (b) maintenance of competitive participation at follow up, and (c) the relation of the level of sports activity and competitive participation at follow up to subjective functional assessments. Also to address the incidence of continued competitive participation despite notable functional problems with the operated knee at 12 months and follow up.

Methods:All patients were competitive athletes before injury and had undergone ACL reconstruction by the transtibial endoscopic technique with either a bone-patellar tendon-bone or a multiple looped hamstring autograft. Evaluation was carried out a mean of 43 months (range 24–73) after surgery by a postal questionnaire in which the Cincinnati sports activity scale (CSAS) and Cincinnati sports function scales were presented in conjunction with closed questions on change in competitive level and the presence of complaints.

Results:Of 109 selected patients, 77 (71%) responded. At follow up, 62 of 77 patients (81%) reported that they had returned to competition within 12 months of surgery. Within the same time frame, 55 of the above 62 patients (89%) also claimed to have returned to the level at which they were competing before injury (or higher). At follow up, 30 of the above 55 patients (54%) reported to still be competing at this high level. Twelve of the above 55 patients (22%) also admitted to major problems with the operated knee at that time. The overall incidence of patients competing despite major functional impairment in the operated knee was 13 of 62 (21%) at 12 months and six of 47 (13%) at follow up. Thirty eight patients (49%) were active in sport at least four times a week at follow up (CSAS level 1), and, using Spearman’s rank correlation between CSAS scores and total sports function scores,rwas calculated to be 0.44. Competitive and male patients had higher total sports function scores at follow up than non-competitive (p  =  0.005) and female (p  =  0.02) patients respectively.

Conclusions:The reported return to competition at the previous level, both within 12 months and at follow up, was high but as expected considering the standard of treatment, patient selection, and study exclusion criteria. Patients with few functional complaints maintained a high level of sporting activity, even after discontinuing competitive participation.
The obesity epidemic: too much food for thought?
Authors: Davey R C
Published: May 2004

Traditional treatment strategies and public health interventions aimed at reducing the incidence of obesity are proving inadequate at controlling the global epidemic of this condition. The main focus of any intervention should be on preventing small excesses of weight, which lead to large weight gain over time, as once a large amount of excess weight is gained, it is very difficult to lose. The only effective approach is for governments to implement radical policy change, to regulate food consumption and control the food industry in a similar way to that of the tobacco industry, by banning the advertising of selected produce, taxing certain foods, and rationing the purchase of others.
Use of statins prior to percutaneous coronary intervention reduces myonecrosis and improves clinical outcome
Authors: Chang Su Min , Yazbek Naji , Lakkis Nasser M.
Published: May 2004

Primary and secondary prevention with statins reduce major cardiac events in patients with coronary artery disease. The impact of pretreatment with statins prior to percutaneous coronary intervention (PCI) is not well established. The objective of this study was to determine if pretreatment with statins prior to PCI reduce myonecrosis and improve clinical outcome. One hundred nineteen consecutive patients with acute coronary syndrome who underwent PCI were identified. We compared the incidence of myonecrosis defined as peak elevation of CK‐MB or CK three time above upper limit of normal within 24 hr and the 6‐month cardiovascular event rate (death, nonfatal myocardial infarction unrelated to PCI, target vessels revascularization, and unstable angina requiring hospitalization) among patients who received statins prior to PCI (n = 63) to those who did not (n = 56). Pretreated patients were more likely to have history of myocardial infarction or revascularization (63% vs. 43%; P = 0.015), hyperlipidemia (80% vs. 48%; P = 0.001), hypertension (83% vs. 49%; P = 0.02), and use of angiotensin‐converting enzyme inhibitor (62% vs. 38%; P = 0.008). The rest of baseline characteristics were similar between the two groups, including use of glycoprotein IIb/IIIa inhibitors, number of diseased vessels, and type of lesions. Patients pretreated with statins had a significantly lower incidence of myonecrosis (2% vs. 10%; P = 0.04) at 24 hr and a significantly lower clinical event (CE) rate at 6 months (17% vs. 21%; P = 0.015). Of patients not pretreated with statins, 72% were taking statins at 6 months as compared to 98% of pretreated patients. After adjusting for all baseline characteristics, use of statins prior to PCI was associated with a marked decrease in risk of all CEs (OR = 0.2; CI = 0.06–0.63; P = 0.006). Statin therapy prior to PCI may reduces peri‐PCI myonecrosis and late cardiac events. These results need to be confirmed in large prospective randomized trials. Catheter Cardiovasc Interv 2004;62:193–197. © 2004 Wiley‐Liss, Inc.
Spontaneous crystallization of potassium chloride from aqueous and aqueous‐ethanol solutions Part 2: Mechanism of aggregation and coalescence of crystals
Authors: Linnikov Oleg D.
Published: May 2004

Published data on aggregation kinetics of potassium chloride crystals at its spontaneous crystallization from supersaturated aqueous and aqueous‐ethanol solutions were analysed. It was found that the crystals coalesced through contact nucleus‐bridges according to the mechanism proposed by Polak. The kinetics of aggregation were described by the Smoluchowski equation for coagulation of colloidal particles. The kinetic coefficient of aggregation process depended on supersaturation, temperature of solution and other characteristics of system. The specific surface energy of potassium chloride 0.98 mJ/m2 was found. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
No‐carrier added synthesis of 18F‐labelled nucleosides using Stille cross‐coupling reactions with 4‐[18F]fluoroiodobenzene
Authors: Wüst Frank R. , Kniess Torsten
Published: May 2004

The radiosyntheses of 5‐(4′‐[18F]fluorophenyl)‐uridine [18F]‐11 and 5‐(4′‐[18F]fluorophenyl)‐2′‐deoxy‐uridine [18F]‐12 are described. The 5‐(4′‐[18F]fluoro‐phenyl)‐substituted nucleosides were prepared via a Stille cross‐coupling reaction with 4‐[18F]fluoroiodobenzene followed by basic hydrolysis using 1 M potassium hy‐droxide. The Stille cross‐coupling reaction was optimized by screening various palladium complexes, additives and solvents. By using optimized labelling conditions (Pd2(dba)3/CuI/AsPh3 in DMF/dioxane (1:1), 20 min at 65°C), 550 MBq of [4‐18F]fluoroiodobenzene could be converted into 120 MBq (33%, decay‐corrected) of 5‐(4′‐[18F]fluorophenyl)‐2′‐deoxy‐uridine [18F]‐12 within 40 min, including HPLC purification. Copyright © 2004 John Wiley & Sons, Ltd.
Radiosynthesis of 3‐[18F]fluoropropyl and 4‐[18F]fluorobenzyl triarylphosphonium ions
Authors: Ravert Hayden T. , Madar Igal , Dannals Robert F.
Published: May 2004

3‐[18F]Fluoropropyl‐, 4‐[18F]fluorobenzyl‐triphenylphosphonium and 4‐[18F]fluorobenzyltris‐4‐dimethylaminophenylphosphonium cations were synthesized in multi‐step reactions from no carrier added (nca) [18F]fluoride. The time for synthesis, purification, and formulation was 56, 82, and 79 min with an average radiochemical yield of 12, 6 and 15%, respectively (not corrected for decay). The average specific radioactivity for the three radiolabeled compounds was 14.9 GB q/µmole (403 mCi/µmole) at end of synthesis (EOS). Copyright © 2004 John Wiley & Sons, Ltd.
Ultrastructure of the annual cycle of female sperm storage in spermathecae of the torrent salamander, Rhyacotriton variegatus (Amphibia: Rhyacotritonidae)
Authors: Sever David M. , Tait Cynthia K. , Diller Lowell V. , Burkholder Laura
Published: May 2004

This study is the first report on the ultrastructure of the sperm storage glands (spermathecae) in the salamander Rhyacotriton variegatus. The population studied is associated with cold‐water, rocky streams of the redwood (Sequoia) zone in northern California. Males possess sperm in their vasa deferentia and undergo spermiation throughout the year, but mating is seasonal. Most females with large, vitellogenic follicles (2.0–3.9 mm mean dia.) collected from February–June contain sperm in their spermathecae, although some females with large follicles lack sperm. Other mature‐size females collected during this period have small ovarian follicles (0.9–1.2 mm mean dia.) and lack stored sperm. All females collected from September–November have small follicles (0.6–1.6 mm mean dia.) and lack sperm, except in one instance in which a female collected in November had a small amount of degraded sperm, apparently retained from the previous breeding season. The spermathecae consist of simple tubulo‐alveolar glands in which the neck tubules produce a mucoid secretory product, and the distal bulbs, where sperm are stored, contain secretory vacuoles of uniform density that stain positively for glycosaminoglycans. In specimens containing sperm, some bulbs have abundant sperm and others lack sperm, but the ultrastructure is similar in both conditions. The acini contain columnar epithelial cells with wide intercellular canaliculi, and a merocrine process releases the secretion. Spermiophagy occurs. In specimens from spring and summer with small ovarian follicles, the neck tubules are similar to those of breeding females, but the distal bulbs are reduced to cords of cells lacking a discernible lumen. Secretory activity in the distal bulbs is initiated in the fall. Spermathecae of R. variegatus are most similar to those of a stream‐dwelling plethodontid, Eurycea cirrigera. J Morphol. 261:1–17, 2004. © 2004 Wiley‐Liss, Inc.
Trichoderma enzymes promote Fibrobacter succinogenes S85 adhesion to, and degradation of, complex substrates but not pure cellulose
Authors: Morgavi Diego P , Beauchemin Karen A , Nsereko Victor L , Rode Lyle M , McAllister Tim A , Wang Yuxy
Published: May 2004

The effects of an enzyme preparation from Trichoderma longibrachiatum (TE) on adhesion and growth of the fibrolytic rumen bacterium Fibrobacter succinogenes S85 was studied to gain a better understanding of the action of feed enzyme additives on fibre digestion by ruminants. Adhesion experiments were performed on crystalline cellulose, corn silage and alfalfa hay. Adhesion of F succinogenes to cellulose was negatively related to the concentration of TE (p < 0.05). At the highest concentration used, TE reduced adhesion to cellulose from 65 to 39%. For corn silage and alfalfa hay, TE stimulated adhesion at low levels (p < 0.05) but this effect was lost at higher levels. Culture experiments were performed on crystalline cellulose and corn silage. The presence of TE in media containing cellulose failed to increase substrate disappearance or gas production although it increased numbers of non‐adherent bacteria (p < 0.05). When corn silage was used, the addition of TE increased NDF disappearance (p < 0.05) at 24 and 48 h (33 and 52% in controls versus 53 and 65% in TE treatments). Growth rate and gas production were also stimulated (p < 0.05). We conclude that, for cellulose, the hydrolytic enzymes in TE obstructed available binding sites decreasing bacterial adherence. Fibrobacter succinogenes digested cellulose efficiently and addition of exogenous cellulases did not further increase substrate disappearance. However, for complex plant substrates, low concentration of TE increased bacterial adhesion and plant (corn) fiber degradation. For the Department of Agriculture and Agri‐Food, Government of Canada, © Minister of Public Works and Government Services Canada 2004. Published for SCI by John Wiley & Sons, Ltd.
A high‐resolution tunable fiber Bragg grating filter
Authors: Tay C. M. , Tan K. M. , Tjin S. C. , Chan C. C. , Ngo N. Q. , Dong X. Y.
Published: May 2004

A tunable fiber Bragg grating (FBG) filter with a tuning resolution of less than one picometer (pm) is demonstrated. The FBG is embedded in carbon‐fiber composite material, which is bent by using a simple mechanical setup. A tuning range of 2 nm and repeatability of less than 0.4% are obtained. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 89–92, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20217
Simulation of ultra‐wideband indoor propagation
Authors: Attiya A. M. , Safaai‐Jazi A.
Published: May 2004

A comprehensive simulation of ultra‐wideband signal propagation in indoor environments is presented. The simulation is based on time‐domain electromagnetic modeling of transmitting and receiving antennas and the analysis of wave propagation through indoor channels using the time‐domain uniform theory of diffraction. The antennas are a pair of TEM horns which are modeled as arrays of vee dipoles. The analysis of these antennas is performed directly in the time domain, without the need for transforming the solutions from the frequency domain to the time domain. The frequency dependence of materials utilized in the structure on the indoor channel is accounted for in the channel simulation. The simulation results are compared with the corresponding measured results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 103–108, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20221
Novel ultra‐wideband discone antenna
Authors: Kim Jinu , Park Seong‐Ook
Published: May 2004

A double‐discone antenna for an ultra‐wideband frequency scan is presented. An exquisite assembly of two inverse‐feeding discone antennas shows a 30:1 broad bandwidth with VSWR below 2.5 and an omnidirectional radiation pattern. These features make the proposed antenna very suitable for both the UWB system antenna and the wideband scan antenna. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 113–115, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20224
Genetic approach to prenatal diagnosis in urea cycle defects
Authors: Häberle Johannes , Koch Hans Georg
Published: May 2004

Objective

To demonstrate the feasibility of prenatal diagnosis by molecular genetics in all urea cycle defects in order to improve and standardize the current approaches.

Methods

Deceased index patients who had suffered from a urea cycle disorder were investigated for mutations of the biochemically most likely affected gene. If no material of index patients was available, parental DNA was studied for obligate carrier status. Fetal cells of 15 pregnancies, either chorionic villi or amniotic fluid cells, were used for direct sequence analysis of the respective mutations. Thirteen families were investigated, of which two were affected by N‐acetylglutamate synthase deficiency, four by carbamoylphosphate synthetase 1 deficiency, one by ornithine transcarbamylase deficiency, three by argininosuccinate synthetase deficiency, two by argininosuccinate lyase deficiency, and one by arginase deficiency.

Results

Molecular genetics allowed the determination of the fetal status in all cases. Besides 14 known mutations, we detected the novel mutation c.544delC of the N‐acetylglutamate synthase gene, the novel missense mutation c.721G>A (E241K) of the argininosuccinate lyase gene, and the novel double mutated allele comprising the known mutation c.703G>A (G235R) and the novel insertion c.712ins[GGACC]2 (254X) of the arginase 1 gene.

Conclusion

Direct genetic analysis of chorionic villi or amniotic fluid cells is feasible, fast, and specific, and can be regarded as the method of choice for prenatal diagnosis in urea cycle disorders. Copyright © 2004 John Wiley & Sons, Ltd.
Base doping and recombination activity of impurities in crystalline silicon solar cells
Authors: Geerligs L. J. , Macdonald D.
Published: May 2004

The optimisation of base doping for industrial crystalline silicon solar cells is examined with model calculations. Focus is on the relation between base doping and carrier recombination through the important impurities interstitial iron (Fei) and the metastable boron–oxygen (BO) complex. Inp‐type silicon, the optimum base resistivity is strongly dependent on defect concentration. Inn‐type silicon, recombination due to Feiis much lower and nearly independent of resistivity. Feiis likely representative for other transition metal impurities. In many real cells a balance between Feior similar defects, and BO will occur. Copyright © 2004 John Wiley & Sons, Ltd.
Hypertext support for the information needs of software maintainers
Authors: Koskinen Jussi , Salminen Airi , Paakki Jukka
Published: May 2004

Making changes safely to programs requires program comprehension and satisfaction of the information needs of software maintainers. In this paper we provide insights into improving hypertext‐based software maintenance support by analyzing those information needs. There exists a series of four earlier, detailed‐level empirical studies on the information needs of professional C program maintainers. We focus on these studies, synthesize their results and determine sources from which the required information might be attained. An experimental research tool, the HyperSoft system, is used to demonstrate the satisfaction of information needs and the system is analytically evaluated against the needs explored by the empirical studies. HyperSoft is based on our transient hypertext approach for software maintenance support. HyperSoft provides automatically generated hypertextual access structures and software visualizations. The results show that transient hypertext is a well‐suited representational form of the typically required versatile information. The discussion also covers related tools and the main features for providing the information required by maintainers are identified. The results show that the focus areas of these tools vary considerably. Copyright © 2004 John Wiley & Sons, Ltd.
On the role of vertical electron density gradients in the generation of type II irregularities associated with blanketing ES (ESb) during counter equatorial electrojet events: A case study
Authors: Devasia C. V. , Jyoti N. , Subbarao K. S. V. , Tiwari Diwakar , Reddi C. Raghava , Sridharan R.
Published: May 2004

The characteristics of different types of Sporadic E (ES) layers and the associated plasma density irregularities over the magnetic equator have been studied in a campaign mode using VHF backscatter radar, digital ionosonde, and ground magnetometer data from Trivandrum (dip latitude 0.5°N, geographic latitude 8.5°N, geographic longitude 77°E), India. The presence of blanketing type ES (ESb) in the ionograms with varying intensity and duration were observed in association with afternoon Counter Equatorial Electrojet (CEEJ) events. ESb was associated with intense backscatter returns and with either very low zonal electric field and/or with distortions present in the altitude profile of the drift velocity of the type II irregularities. The results of the coordinated study indicate the possible role of vertical electron density gradients in ESb layers in addition to providing evidence for the local winds to be responsible for the vertical gradients themselves.
Eulerian short-time statistics of turbulent flow at large Reynolds number
Authors: Brouwers J. J. H.
Published: May 2004

An asymptotic analysis is presented of the short-time behavior of second-order temporal velocity structure functions and Eulerian acceleration correlations in a frame that moves with the local mean velocity of the turbulent flow field. Expressions in closed-form are derived which cover the viscous and inertial subranges. They apply to general anisotropic turbulence at a large Reynolds number obeying the Kolmogorov theory. Previously published results for isotropic turbulence emerge as special cases. In the derivation use is made of the approximation of temporarily frozen turbulence proposed by Tennekes. It is shown to be valid under conditions not other than those for which the Kolmogorov hypotheses hold. The effects of intermittency appear to be marginal.
Effective force fields for condensed phase systems from ab initio molecular dynamics simulation: A new method for force-matching
Authors: Izvekov Sergei , Parrinello Michele , Burnham Christian J. , Voth Gregory A.
Published: May 2004

A novel least-squares fitting approach is presented to obtain classical force fields from trajectory and force databases produced by ab initio (e.g., Car–Parrinello) molecular dynamics (MD) simulations. The method was applied to derive effective nonpolarizable three-site force fields for liquid water at ambient conditions from Car–Parrinello MD simulations in the Becke–Lee–Yang–Parr approximation to the electronic density functional theory. The force-matching procedure includes a fit of short-ranged nonbonded forces, bonded forces, and atomic partial charges. The various parameterizations of the water force field differ by an enforced smooth cut-off applied to the short-ranged interaction term. These were obtained by fitting to the trajectory and force data produced by Car–Parrinello MD simulations of systems of 32 and 64 H2O molecules. The new water force fields were developed assuming both flexible or rigid molecular geometry. The simulated structural and self-diffusion properties of liquid water using the fitted force fields are in close agreement with those observed in the underlying Car–Parrinello MD simulations. The resulting empirical models compare to experiment much better than many conventional simple point charge (SPC) models. The fitted potential is also shown to combine well with more sophisticated intramolecular potentials. Importantly, the computational cost of the new models is comparable to that for SPC-like potentials.
Photodissociation and multiphoton dissociative ionization processes in CH3S2CH3 at 193 nm studied using velocity-map imaging
Authors: Martı́nez-Haya B. , Bass M. J. , Brouard M. , Vallance C. , Torres I. , Barr J.
Published: May 2004

Dissociation and ionization processes in dimethyl disulfide, CH3S2CH3, induced by one- or two-photon absorption of 193 nm light, have been studied using velocity-map ion imaging. The analysis of the ion images of the CH3S2+, CH3S+, S2+, and S+ fragments has allowed the characterization of the scattering dynamics of some of the main photolysis and dissociative-ionization processes. In particular, the experiments corroborate the formation of electronically excited SCH3(2A1) products in the 193 nm photodissociation of dimethyl disulfide seen in earlier studies, and show that laser ionization provides a very sensitive method for their detection. The data have also allowed determination of the recoil energy and angular distributions of the CH3S2+ and CH3S+ products of the two-photon dissociative-ionization of the CH3S2CH3 molecule. The measured distributions for these products are consistent with the formation of a transient parent ion which dissociates after a substantial intramolecular rearrangement, possibly yielding the most stable isomeric forms of the fragments, namely CH2S2H+ and CH2SH+.
Waveguide networks in three-dimensional layer-by-layer photonic crystals
Authors: Sell Curtis , Christensen Caleb , Muehlmeier Jason , Tuttle Gary , Li Zhi-Yuan , Ho Kai-Ming
Published: May 2004

Different types of waveguides and connections between them were fabricated in a three-dimensional (3D) layer-by-layer photonic crystal. The waveguides were formed by removing either a single rod or a series of rod fragments running in three mutually orthogonal directions. This provides the potential of forming a 3D network of waveguide channels with cross sectional dimensions on the order of one lattice constant. The propagation behavior of guided modes in these waveguide networks was probed using a network analyzer. High transmission efficiency (with loss below 0.5 dB) through various waveguide bends and networks with carefully designed geometries has been achieved.
Folding behavior of model proteins with weak energetic frustration
Authors: Locker C. Rebecca , Hernandez Rigoberto
Published: May 2004

The native structure of fast-folding proteins, albeit a deep local free-energy minimum, may involve a relatively small energetic penalty due to nonoptimal, though favorable, contacts between amino acid residues. The weak energetic frustration that such contacts represent varies among different proteins and may account for folding behavior not seen in unfrustrated models. Minimalist model proteins with heterogeneous contacts—as represented by lattice heteropolymers consisting of three types of monomers—also give rise to weak energetic frustration in their corresponding native structures, and the present study of their equilibrium and nonequilibrium properties reveals some of the breadth in their behavior. In order to capture this range within a detailed study of only a few proteins, four candidate protein structures (with their cognate sequences) have been selected according to a figure of merit called the winding index—a characteristic of the number of turns the protein winds about an axis. The temperature-dependent heat capacities reveal a high-temperature collapse transition, and an infrequently observed low-temperature rearrangement transition that arises because of the presence of weak energetic frustration. Simulation results motivate the definition of a new measure of folding affinity as a sequence-dependent free energy—a function of both a reduced stability gap and high accessibility to non-native structures—that correlates strongly with folding rates.
Determination of low-pressure crystalline–liquid phase boundary of SnI4
Authors: Fuchizaki Kazuhiro , Fujii Yasuhiko , Ohishi Yasuo , Ohmura Ayako , Hamaya Nozomu , Katayama Yoshinori , Okada Taku
Published: May 2004

The location of the liquidus in the low-pressure crystalline phase of SnI4 was determined utilizing in situ x-ray diffraction measurements under pressures up to approximately 3.5 GPa. The liquidus is not well fitted to a monotonically increasing curve such as Simon’s equation, but breaks near 1.5 GPa and then becomes almost flat. The results are compared to those from molecular dynamics simulations. Ways to improve the model potential adopted in the simulations are discussed.
Low aberration permanent hexapole magnet for atom and molecular beam research
Authors: Dworski S. , Alexandrowicz G. , Fouquet P. , Jardine A. P. , Allison W. , Ellis J.
Published: May 2004

We present details of an 800-mm-long, 4.80 mm bore, 1.32 T pole-tip field permanent hexapole (sextupole) magnet system with exceptionally low field aberrations. The assembly was developed as an atom optical element for use in the Cambridge He3 Spin-Echo Spectrometer. Our 12 segment magnet is an improved version of the well-known Halbach design, in which we refine the pole piece shape to improve the field characteristics. Semi-analytic simulations and finite element modeling were performed to optimize the pole piece shape, in order to maximize field strength while minimizing higher order multipole aberrations. High precision machining and assembly techniques were used to construct the device and the resultant field was measured. The measured pole-tip field of 1.25 T is in good agreement with the simulations (5% error) and the measured aberrations that are at least 5 times smaller than those theoretically possible with an ideal 12 segment system using the conventional design. Finally, the application of the hexapole magnet was demonstrated in our spectrometer, as a composite magnetic lens, used to analyze the nuclear spin of surface-scattered He3 atoms from a polarized incident beam.
Normal and torsional spring constants of atomic force microscope cantilevers
Authors: Green Christopher P. , Lioe Hadi , Cleveland Jason P. , Proksch Roger , Mulvaney Paul , Sader John E.
Published: May 2004

Two methods commonly used to measure the normal spring constants of atomic force microscope cantilevers are the added mass method of Cleveland et al. [J. P. Cleveland et al., Rev. Sci. Instrum. 64, 403 (1993)], and the unloaded resonance technique of Sader et al. [J. E. Sader, J. W. M. Chon, and P. Mulvaney, Rev. Sci. Instrum. 70, 3967 (1999)]. The added mass method involves measuring the change in resonant frequency of the fundamental mode of vibration upon the addition of known masses to the free end of the cantilever. In contrast, the unloaded resonance technique requires measurement of the unloaded resonant frequency and quality factor of the fundamental mode of vibration, as well as knowledge of the plan view dimensions of the cantilever and properties of the fluid. In many applications, such as frictional force microscopy, the torsional spring constant is often required. Consequently, in this article, we extend both of these techniques to allow simultaneous calibration of both the normal and torsional spring constants. We also investigate the validity and applicability of the unloaded resonance method when a mass is attached to the free end of the cantilever due to its importance in practice.
Image-based autonomous micromanipulation system for arrangement of spheres in a scanning electron microscope
Authors: Kasaya Takeshi , Miyazaki Hideki T. , Saito Shigeki , Koyano Koichi , Yamaura Tomio , Sato Tomomasa
Published: May 2004

The micromanipulation technique in a scanning electron microscope (SEM) has been attracting interest as a technique to produce microstructures such as three-dimensional photonic crystals or advanced high-density electronic circuits. However, it is difficult to fabricate a large-scale structure or to conduct a systematic experiment using numbers of structures, as long as we rely on manually operated micromanipulation. In this study, we constructed an automatic system which arranges 10-μm-sized microspheres into a given two-dimensional pattern in a SEM. The spheres are picked up by touching with the center of the planar tip of a probe (needle), and placed on the substrate by moving the contact point to the edge of the tip and inclining the probe. The positions of the probe and the spheres are visually recognized from the SEM image from above and the optical microscope image from the side. The generalized Hough transform, which can robustly detect arbitrary shape from the edge fragments, is employed for the image recognition. Contact force information obtained by a force sensor with a resolution of 14 μN is also utilized for the control. Completely automatic rearrangement of randomly sprinkled metal spheres with a diameter of 30 μm into arbitrary patterns was successfully demonstrated. Autonomous micromanipulation technique under the observation of a SEM would contribute not merely to laboratories but also to the opto-electronics industry.
Presliding friction identification based upon the Maxwell Slip model structure
Authors: Rizos Demosthenis D. , Fassois Spilios D.
Published: May 2004

The problem of presliding friction identification based upon the Maxwell Slip model structure, which is capable of accounting for the presliding hysteresis with nonlocal memory, is considered. The model structure’s basic properties are examined, based upon which a priori identifiability is established, the role of initial conditions on identification is investigated, and the necessary and sufficient conditions for a posteriori identifiability are derived. Using them, guidelines for excitation signal design are also formulated. Building upon these results, two new methods, referred to as Dynamic Linear Regression (DLR) and NonLinear Regression (NLR), are postulated for presliding friction identification. Both may be thought of as different extensions of the conventional Linear Regression (LR) method that uses threshold preassignment: The DLR by introducing extra dynamics in the form of a vector finite impulse response filter, and the NLR by relaxing threshold preassignment through a special nonlinear regression procedure. The effectiveness of both methods is assessed via Monte Carlo experiments and identification based upon laboratory signals. The results indicate that both methods achieve significant improvements over the LR. The DLR offers the highest accuracy, with the NLR striking a very good balance between accuracy and parametric complexity.
Propagation of an intense femtosecond laser pulse through a thin foil filter
Authors: Kinoshita Kenichi , Zhidkov Alexei , Hosokai Tomonao , Ohkubo Takeru , Uesaka Mitsuru
Published: May 2004

In order to improve the contrast of a nanosecond prepulse, the interaction of 12 TW, 50 femtosecond laser pulses with thin foil, as a filter, is investigated. Due to the collisional absorption, the prepulse produces rapidly expanding plasma and can lose 90% of its energy. At a properly chosen thickness of the filter, more than 60% of energy of the femtosecond main pulse is shown to be transmitted through the expanded underdense plasma with reduced prepulse contrast ratio.
Characterization of breakdown in ultrathin oxides by hot carrier emission
Authors: Tsang J. C. , Linder B. P.
Published: May 2004

Hot carrier luminescence excited at low voltages across ultrathin gate oxides is used to describe the localized transport during progressive oxide breakdown. The emission identifies the locations of initial breakdown spots in field effect transistors. The transitions from stress-induced leakage currents to reversible breakdown to final breakdown are accompanied by changes in the efficiency of the emission showing an evolution from inelastic to elastic transport.
Terahertz emission by InN
Authors: Ascázubi Ricardo , Wilke Ingrid , Denniston Kyle , Lu Hai , Schaff William J.
Published: May 2004

We report on optically excited terahertz (THz) emission by indium nitride (InN) thin films. We have used 70 fs titanium–sapphire laser pulses with wavelengths at 800 nm to generate THz-radiation pulses. The InN thin films are deposited on sapphire substrates with GaN buffer layer by molecular-beam epitaxy. The THz-radiation emitted from the InN surface is significantly stronger than that of the GaN/InN interface. The origin of the THz emission are transient photocarrier currents. These results are in agreement with recent experimental results of InN which show that this material is a small band-gap semiconductor. The magnitude of the THz emission from the InN is strong compared to THz emission from previously investigated semiconductors.
Subwavelength emitters in the near-infrared based on mercury telluride nanocrystals
Authors: Olk P. , Buchler B. C. , Sandoghdar V. , Gaponik N. , Eychmüller A. , Rogach A. L.
Published: May 2004

The optical properties of near-infrared-emitting mercury telluride (HgTe) nanocrystals are investigated using fluorescence confocal microscopy. The HgTe quantum dots were coated with a “layer-by-layer” process on latex spheres with diameters down to 150 nm and number of layers varying from 1 to 3. The individual spheres act as bright subwavelength light sources. Measurements of the fluorescence decay show that the lifetime varies with the number of nanocrystal layers.
Fast Fourier demodulation
Authors: Carmon Yuval , Ribak Erez N.
Published: May 2004

We present a fast Fourier demodulation method for calculating the distortion in a repetitive pattern. The technique is based on applying digital demodulation, then using only the anti-Hermitian part of the pattern in Fourier space. After demodulation, we are left with the Fourier transform of the sought phase information only. Using also the Hermitian part, we would have gotten the object itself. We investigate the boundaries of the technique, as related to aberration content, amplitude variations, and sensitivity to noise.
Material modifications induced by laser annealing in two-dimensional structures
Authors: La Magna Antonino , Alippi Paola , Privitera Vittorio , Scalese Silvia , Pannitteri Salvatore , Fortunato Guglielmo , Mariucci Luigi , Camalleri Marco
Published: May 2004

The effects of the laser irradiation on metal-oxide-semiconductor structures are investigated by means of a phase-field methodology. We numerically solved the model equations in one- and two-dimensional structures also containing SiO2/amorphous-Si/crystalline-Si stacks. The simulated laser annealing processes are discussed in detail, pointing out the influence of the geometrical constraints on the irradiation effects in the samples. The simulation results are compared with the experimental two-dimensional delineation of dopant profiles. These comparisons show the importance of the joint theoretical and experimental investigations in order to fully understand the phenomena occurring in submicron sized laser irradiated structures.
La
0.7
Pr
0.3
MnO
3
ceramic: An electron-doped colossal magnetoresistive manganite
Authors: Duan Ping , Chen Zhenghao , Dai Shouyu , Zhou Yueliang , Lu Huibin , Jin Kuijuan , Cheng Bolin
Published: May 2004

We report a study on the synthesis, electrical transport, and magnetic properties of Pr-doped LaMnO3 ceramic material. We have found that La1−xPrxMnO3+δ (x=0.3) synthesized using solid-state reaction shows semiconductor behavior, and no colossal magnetoresistance (CMR) effect; while it shows CMR behavior when it is annealed in a flowing argon at certain temperature (about 873 K), which suggests that La0.7Pr0.3MnO3+δ has been transferred to La0.7Pr0.3MnO3. The x-ray photoemission spectroscopy reveals that Pr ions are in a mixed-valence state of Pr4+ and Pr3+ in this compound. Therefore, La1−xPrxMnO3 (x=0.3) could be an electron-doped CMR manganite.
Dipolar interaction effects on the thermally activated magnetic relaxation of two-dimensional nanoparticle ensembles
Authors: Denisov S. I. , Lyutyy T. V. , Trohidou K. N.
Published: May 2004

The thermally activated magnetic relaxation in two-dimensional lattices of dipolar interacting nanoparticles with large uniaxial perpendicular anisotropy is studied by a numerical method and within the mean-field approximation for comparison. The role that the correlation effects play in magnetic relaxation and the influence of lattice structure and bias magnetic field on the relaxation process are revealed. The correlations of the nanoparticle magnetic moments enhance relaxation on small times, delay it on large times, and reduce the steady-state absolute magnetization at nonzero bias fields. In a hexagonal lattice, magnetic relaxation on small times occurs faster and the steady-state absolute magnetization has the larger magnitude than in a square lattice with the same lattice spacing.
Stimulated resonance Raman scattering from epitaxially oriented crystals of biphenyl-capped thiophene
Authors: Yanagi Hisao , Yoshiki Atsutoshi
Published: May 2004

Spectrally narrowed light emission based on stimulated resonance Raman scattering has been observed for epitaxially grown needle crystals of a biphenyl-capped thiophene oligomer. Under optical pumping with a wavelength-tuned pulse laser, the crystals emitted a couple of sharp lines (full width at half maximum ∼0.3 nm) along the direction of the needle axis. In particular, the intense line with a Raman shift of 1435 cm−1 appeared at low excitation energy of a few μJ/pulse. This Raman line was assigned as the symmetric in-plane stretching mode of the molecule. The observed Raman-associated lasing suggests the presence of polaritonic interaction between the uniaxially ordered molecular excitons and emitted photons.
Tunable-focus flat liquid crystal spherical lens
Authors: Ren Hongwen , Fan Yun-Hsing , Gauza Sebastian , Wu Shin-Tson
Published: May 2004

A tunable-focus spherical lens using two flat substrates and inhomogeneous electric field over a homogeneous liquid crystal (LC) layer is demonstrated. The top flat substrate has an imbedded spherical indium–tin–oxide (ITO) electrode and the bottom has a planar ITO electrode on its inner surface. The inhomogeneous electric field generates a centrosymmetric gradient refractive index profile within the LC layer which causes the focusing behavior. The focal length of the LC lens can be tuned continuously from infinity to 0.6 m by the applied voltage.
Deep blue widely tunable organic solid-state laser based on a spirobifluorene derivative
Authors: Schneider D. , Rabe T. , Riedl T. , Dobbertin T. , Werner O. , Kröger M. , Becker E. , Johannes H.-H. , Kowalsky W. , Weimann T. , Wang J. , Hinze P. , Gerhard A. , Stössel P. , Vestweber H.
Published: May 2004

We report on amplified spontaneous emission and optically pumped deep blue lasing in the organic spirobifluorene derivative 2,7-bis(biphenyl-4-yl)-2′,7′-di-tert-butyl-9,9′-spirobifluorene. Solid-state lasing is observed in thin films of this material deposited on a distributed-feedback (DFB) grating substrate. The laser wavelength can be tuned from 401.5 to 434.2 nm depending on the grating period of the Bragg reflector. The blue edge of this interval at 401.5 nm makes this laser an extremely short wavelength organic DFB laser. When pumping with a pulsed nitrogen laser at 337 nm, we observe a laser threshold energy density of 83 μJ/cm2. These results render this spiro compound an excellent candidate for blue-emitting diode lasers.
Electroluminescence from self-organized “microdomes”
Authors: Karthaus Olaf , Adachi Chihaya , Kurimura Shigeya , Oyamada Takahito
Published: May 2004

The preparation of a self-organized, microstructured organic electroluminescent device is reported. A dewetting process is used to form (sub)micrometer-sized dewetted patches (“domes”) of a hole transport material (tolyl-phenyl-diaminobiphenyl, TPD) on an indium-tin-oxide electrode. The domes are regular in size and spacing. Evaporation of an electron transport material (tris-8-hydroxyquinoline aluminum, Alq3) and an Mg/Ag top electrode leads to a device with electroluminescing spots of micrometer dimensions and a spacing of a few micrometers.
Origin of low-friction behavior in graphite investigated by surface x-ray diffraction
Authors: Yen Bing K. , Schwickert Birgit E. , Toney Michael F.
Published: May 2004

Contrary to popular belief, the slipperiness of graphite is not an intrinsic property. The presence of vapors, such as water, is required for graphite to lubricate; in vacuum or dry environments, the friction and wear rate of graphite are high. A widely accepted explanation involves weakening of the binding force between basal planes near the surface, thereby allowing these planes to shear easily. This weakening results from proposed chemisorption or intercalation of vapor molecules near the surface, leading to an increase in the interlayer spacing between near-surface basal planes. Here we use x-ray diffraction from a synchrotron source to show that the basal plane spacing at the surface is the same in vacuum, ambient air, or water vapor saturated air. These results refute this long-held view that the low friction behavior of graphite is due to shearing of weakened basal planes.
Synthesis of Nitrogen Heterocycles by Rhodium-Catalyzed Hydroformylation of Polymer-Attached Amino Alkenes with Syngas
Authors: Illesinghe Jayamini , Campi Eva M. , Jackson W. Roy , Robinson Andrea J.
Published: May 2004

Rhodium(I) phosphite catalyzed hydroaminomethylation of resin-tethered amino alkenes with H2/CO gives moderate to good yields of five-, eight-, ten-, and thirteen-membered heterocycles. Competing hydrogenation, dimerization, or polymerization reactions were not observed using this methodology.