bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomic-Assisted Breeding Tools for Grain and Nutritional Quality Improvement in Rice
Authors: Patra Biswaranjan , Majhi Prasanta Kumar , Tripathy Swagat Kumar , Tripathy Sourav Priyadarsi , Khan Afreen , Behera Partha Pratim , Das S. , Ahamad Ayaz
Published: February 2022

More than half of the world’s population consumes rice as a staple food in their diet. Rice grain quality is receiving attention from both consumers and producers as living standards in rice-consuming regions has improved and this emerged as a critical rice breeding target. Grain quality traits have a strong influence on the market value of rice and the adoption of new varieties by farmers. Consumer preferences for specific nutritional, physical, eating, and cooking characteristics are at the root of these. Uniform grain width, length, colour (translucence or whiteness), and chalkiness are all desirable physical properties. Cooking and eating (organoleptic) characteristics such as; cooking time (gelatinization temperature and viscosity), the ability of rice to remain soft after cooking (gel consistency), and textural properties of cooked rice (amylose content and aroma) are also very important. Plant breeders are always working hard to meet these demands by developing new rice varieties. The genomics era provides many opportunities to assist breeders in addressing these challenges. While not complete, our understanding of the genetic basis underlying many grain quality traits is expanding. There have been reports of quantitative trait loci (QTL) controlling grain appearance, chalkiness, protein content, and grain length. Genomic-assisted Breeding techniques such as marker-assisted selection, QTL mapping, genome editing, genome wide association studies, and genetic engineering can provide further a better understanding of the genetic basis and thus help to improve rice grain nutritional quality traits.
Comparative Evaluation of the Effects of Lighting Conditions on the Shade Selection of Ceramics using Visual Method
Authors: Kawade Rewa , Kambala Seema Sathe
Published: February 2022

Background: Tooth shade selection in prosthodontic restorations largely affects the patient satisfaction. Natural daylight is considered as the most recommended and standard source for shade selection. However, due to its inconsistency, shade matching lights have been introduced as an attempt to standardize the effect of light source.

Objectives: Comparative evaluation of the effects of daylight, shade matching light and dental operating light against the grey background on visual shade matching of natural teeth with VITA Classic shade guide. Daylight will be taken as the control group.

Methodology: Shade matching will be conducted in a well illuminated area with grey background. A group of 5 observers with superior color discrimination competence as determined by Pseudo Isochromatic colour test will be chosen for teeth shade matching. The matching will be carried out for 125 subjects under the three lighting conditions. The visual assessment will be done by matching the shade of maxillary central incisor of the subject with VITA Classic shade guide. Comparison will be done for two lighting conditions, each observer will perform this test three times that is for grey background in daylight, shade matching light and dental operatory light.

Expected Results: This study will determine the lighting condition that could be used as a possible alternative of daylight.

Conclusion: It will depict the lighting conditions that will best help the clinician to select the shade that will enhance the esthetics of the prosthesis and restorations.
Detection of 11 Multidrug Resistance Genes among the Strains of A. Baumannii by Computational Approach
Authors: Noufal Z. Mohamed , Girija A. S. Smiline , Ganesh P. Sankar , Priyadharshini J. Vijayashree
Published: February 2022

Background: Acinetobacter baumannii is typically short, rod shaped gram negative bacterium. The World Health Organisation has declared it as an opportunistic pathogen in humans. Multi drug resistance involves different genetic determinants making the pathogen difficult to treat. So this study is undertaken to characterize the 11 different drug resistant genes from 19  virulent strains of A. baumannii using in-silico PCR.

Aim: Detect the 11 multidrug resistance genes among strains of A. baumannii by computational approach.

Materials & Methods: 11 multidrug resistance genes of A. baumannii were selected. Forward and reverse primers of the 11 genes as reported from earlier studies were used for in-silico PCR amplification. 19 strains of A .baumannii set as default strains on the server were chosen and the amplicon bands were observed. 

Result: Among the 11 multidrug resistance genes only blaOXA-51like and blaADC were detected among the 19 virulent strains of A. bauamannii.

Conclusion: The findings of the study documents the frequency of blaADC and blaOXA-51 like from the selected strains of A. baumannii. However further experimental validation must be done towards the periodical surveillance on the drug resistant strains of A. baumannii in hospital settings.
Multiorgan Involvement in COVID-19 Patients: A Review
Authors: Shrivastava Nimisha , Tivaskar Suhas , Luharia Anurag , Christian Ravi
Published: February 2022

Summary: The episode of severe intense respiratory disorder coronavirus 2 (Sars-CoV2) in December 2019 frame Wuhan, China, leads to widespread coronavirus illness 2019 (COVID-19). Whereas the common cold indications are watched in mellow cases, COVID-19 goes with multiorgan disappointment in extreme patients. The association of different organs in severe patients results from protracting the hospitalization item and expanding the immortality irate. In this survey, we were appointed to investigate the association of other organs in COVID-19 patients, especially in extreme cases. Too, we attempted to define the potential underlying components of SARS-CoV2 actuated multiorgan disappointment. The multiorgan brokenness is characterized by acute lung disappointment, intense liver disappointment, intense kidney harm, cardiovascular disorder, and as well as in a wide range of hematological abnormalities and neurological clutters. The main imperative components are related to the coordinate and circuitous pathogenic features of SARS-CoV2.

Conclusion: Understanding the clinical, research facility, and radiological highlights of COVID-19 in fundamentally unwell patients with multi-organ failure should be clarified for the clinician. As a result, extending the information on the pathophysiology of SARS-COV2-induced multi-organ disappointment may result in way better methods to treat COVID-19-patients and diminish the related dismalness and mortality.
A Study on Reducing the Discharge Turnaround Time of IPD Patients at AVBRH
Authors: Chaudhari Pratiksha Suresh , Shinde Vitthal , Gudhe Vandana
Published: February 2022

Background: Smooth and patient-friendly admission and discharge processes attract a good number of patients and improve hospital turnover, ultimately bringing good profits to hospitals within optimum use of resources. Delay in the discharge process causes stagnation of patients, ultimately affecting new admissions. Discharge procedures for some critical patients are complicated and challenging.  A lot of time is spent on discharge intimation, billing, Pharmacy Clearance, handover, etc.  This study aims to assess the discharge process causes of delay in discharge and reflect on ways to improve the efficiency of the discharge process so that the discharge turnaround period can be reduced.

Methodology: This will be a Retrospective Observational study conducted in AVBRH, Wardha. Data will be collected from 60 discharged patients admitted to IPD wards. Data will be collected using a structured questionnaire during personal interviews. Data will be analyzed using appropriate statistical tools.

Expected Results: Some administrative and management gaps and handover gaps are expected to be found, which can be corrected to increase the efficiency of the discharge process.

Conclusion: This Will be drawn as per the findings of study.
Comparative Evaluation of Remineralization Potential of Acidulated Phosphate Fluoride and Hydroxyapatite Nanoparticles with and without Iontophoresis on the Incipient Carious Lesion in Permanent Teeth
Authors: Ragit Rutuja , Rathi Nilesh , Thosar Nilima , Khubchandani Monika
Published: February 2022

Background: A non- invasive method used to improve the drug delivery with the help of electric arena is termed as Iontophoresis. The iontophoresis process may cause deeper penetration of ions using electric current. Remineralizing nanomaterial may be infused at higher concentrations in the deeper layer of incipient caries under the influence of iontophoresis. Hydroxyapatite crystals are the most stable form of calcium phosphate which is responsible for the mechanical strength of the dental tissues. Improvedre-mineralization occurs more with the apatite particle size of less than 4 µm. Due to the size of the nanocomplexes ofhydroxyapatite, there can be possibilities that they would enter the porosities and diffuse into the body of the subsurface lesion to enhance remineralization using iontophoresis technique.

Objectives: 1) To evaluate the remineralization potential of APF gel with or without iontophoresis on the incipient carious lesion in permanent teeth. 2) To evaluate the remineralization potential of hydroxyapatite nanoparticles with or without iontophoresis on the incipient carious lesion of permanent teeth. 3) To compare the remineralization potential of APF gel and hydroxyapatite nanoparticles with or without iontophoresis on the incipient carious lesion in permanent teeth.

Methodology: Forty extracted intact teeth will be taken and artificial caries will be induced.  These specimens will be randomly divided into five groups as per the treatment - 1) APF gel application 2) APF gel with iontophoresis 3) Hydroxyapatite nanoparticles solution application 4) Hydroxyapatite nanoparticles solution with iontophoresis 5) Distilled water (control group). Remineralization will be analysis by using Vickers hardness test.  The alterations in the carious lesion will be assessed by confocal laser scanning microscopy.

Expected Results: APF gel and hydroxyapatite nanoparticles with iontophoresis will give superior remineralization effect as compared to the conventional method.

Conclusion: The utilization of the iontophoresis with hydroxyapatite nanoparticle will provide improved mineralization of incipient caries and prove to be a better method for treatment.
Knowledge, Awareness and Practice of Periodontal Therapy during Pregnancy among Dental Professionals
Authors: Santhanam P. , Jeevitha M. , Jayaraman Selvaraj , Kumar M. Naveen
Published: February 2022

Aim: To assess the knowledge, awareness and practice of periodontal therapy during pregnancy among dental professionals

Materials and Methods: This cross-sectional study was conducted among 100 dental professionals in and around Chennai. A well-structured questionnaire consisted of 18 questions which were used to assess the awareness of periodontal therapy during pregnancy among dental professionals. Simple randomised sampling method was used to categories the sample population (online survey participants).The knowledge, awareness, scores were calculated for the correct answers to the questions. Based on their response data were statistically analysed.

Results: Based on statistical analysis results were tabulated. Around 74% of participants were undergraduates and 26% were postgraduates. Around 64% of the participants were aware of adverse pregnancy outcomes associated with periodontal disease. 80% of the participants were aware that pregnant patients must be turned to the left side on a dental chair for any dental examination and treatment.

Conclusion: The results of the present study showed that knowledge and awareness of periodontal therapy during pregnancy among dental professionals are appreciable among postgraduates than undergraduates. The attitude of the dental professionals, particularly undergraduates toward bringing the facts into clinical practice needs to be improved through integrated programs which can provide better and safe treatment to pregnant patients.
Bronze Age farms and Iron Age farm mounds of the Outer Hebrides
Authors: Barber John , Collins Geoffrey , Crone Lisbeth , Duffy Alan , Dugmore Andrew , Finlay Nyree , Forbes Will , Gibson Annemarie , Halstead Paul , Hirons Kenneth , James Heather , Jones Andrew , Jones Glynis , Lee Frances , Lehane Daragh , MacSween Ann , Mannion Antoinette , Mate Ian D , McCullagh Roderick , Moseley S P , Newton Anthony , Pain Chris , Powers Alix , Rideout James , Ritchie William , Scott E , Serjeantson Dale , Smith Andrea , Thew Nigel
Published: February 2022

Hebridean sites of the coastal sand cliffs and associated machair, or sandy plain have been known for many years. Artefacts and ecofacts of various types have long been collected from archaeological sites in the eroding sand-cliffs of the machairs of the Outer Hebrides. Early in 1983, personnel of the then Central Excavation Unit of Historic Scotland's predecessor revisited very nearly all of the coastal archaeological sites then known in the Long Isle, with the specific task of identifying those at immediate threat from coastal erosion and of assessing the feasibility of their excavation or preservation. Some 32 sites were seen to be undergoing active erosion; at nine of them preservation was not being pursued and excavation was feasible. These sites were of two morphotypes: sites exposed in roughly vertical sand-cliffs and sites exposed over relatively large horzontal areas of sand deflation. It was decided to examine one sand-cliff site along its exposed face. The site selected was Balelone in North Uist, its excavation designed to explore both the problems associated with the excavation of deep midden sites with complex stratigraphy and the not-inconsiderable problems of excavation in sand. In the light of the Balelone trial excavation, a new approach was called for. A structured approach aimed firstly at establishing the three-dimensional extent of the sites to be examined. Four sites were then sampled in locations at Baleshare (NGR: NF 776 615), Hornish Point (NGR: NF 758 472), South Glendale (NGR: NF 798 143) and Newtonferry (NGR: NF 89511 78288) within a rigorously-defined research framework.
Clinical significance of quantitative blood cultures in newborn infants
Authors: Sabui T , Tudehope DI , Tilse M
Published: July 2002

Aim: To evaluate quantitative blood culture as a secondary test on a positive blood culture for the diagnosis of sepsis in newborn infants.

Method: A 15‐month prospective study of colony forming units (CFU) on positive blood cultures from newborn infants clinically suspected of having bacterial sepsis. Growth of bacteria in peripheral blood cultures was quantified using the isolater 1.5 microbial tube lysis direct plating culture system. Colony forming units were evaluated against a clinical assessment of infection.

Results: Of 137 positive blood cultures, 71 (51.8%) were taken from neonates with clinically defined infection and 66 (48.2%) were from non‐infected infants. The clinical and biographical data in these two groups were similar. Coagulase negative staphylococci were the most commonly isolated organisms in each group (60.6%vs 93.9%). Eight deaths from sepsis occurred in the clinically infected group. Eighty‐five per cent of sepsis was late onset. Although a CFU count ≥ 30/mL predicted sepsis (sensitivity 83%, specificity 60%, positive predictive value 69%, negative predictive value 76%), a CFU count < 30/mL did not rule out serious sepsis. The higher the CFU count the greater the likelihood of sepsis.

Conclusion: Quantitative blood culture was not shown to be a sensitive secondary test on a positive blood culture to distinguish clinical sepsis from culture contamination. Although a positive threshold of ≥ 30 CFU/mL proved to be optimal, improvement in test performance would be expected with a lower incidence of culture contamination.
Patterns and Ecological Correlates of Pollination Modes Among Bromeliad Communities of Andean Forests in Bolivia
Authors: Kessler M. , Krömer T.
Published: July 2002

Abstract: We studied the distribution of five pollination modes (ornithophily, chiropterophily, entomophily, mixed/unspecific, autogamy) among the bromeliad communities of 74 forest sites in the Bolivian Andes and adjacent lowlands. We recorded a total of 188 bromeliad species belonging to 16 genera, including 115 (61 %) ornithophilous, 14 (7 %) chiropterophilous, 45 (24 %) entomophilous, 8 (4 %) autogamous, and 6 (3 %) species with mixed pollination mode. Ornithophily was the dominant pollination mode at high elevations and in wet regions, while entomophily dominated in arid regions. Chiropterophily was most common in wet lowland regions, autogamy in arid sites, and mixed pollination in the lowlands. Pollination modes were rather evenly distributed among life‐forms and ecophysiological types, with a few exceptions: terrestrial forest bromeliads, mostly belonging to unarmed, soft‐leaved taxa, had a prevalence of entomophily and few ornithophilous species; large, spiny terrestrial bromeliads of Puya and Bromelioideae showed a prevalence of ornithophily; and autogamy was restricted to the neotenous subgenus Diaphoranthema of Tillandsia. The restriction of unspecific pollination modes to the lowlands is hypothesized to be related to the abundance of pollinators, eliminating the need for specialized co‐evolution, or to the overall rarity of bromeliads in this environment, precluding the development of specialized relationships. The low representation of entomophilous species in small dry forest regions compared to extensive areas is assumed to be due to the seasonal influx of hummingbirds and/or bats. Overall, the frequency of individual pollination modes was related to the availability of pollinators as determined by temperatures and humidity.
Exact analysis of an idealized model for calculating the photoresponse of a preferentially doped polycrystalline solar cell
Authors: Elnahwy S. , Adeeb N.
Published: July 2002

Analytical expressions are derived for the photoresponse of a simplified model for a preferentially doped polycrystalline solar cell. The expressions are used to investigate the dependence of the photoresponse and the total short circuit current on the depth of preferential doping for different grain sizes.
Simple, very low dark current, planar long-wavelength avalanche photodiode
Authors: Liu Y. , Forrest S. R. , Ban V. S. , Woodruff K. M. , Colosi J. , Erikson G. C. , Lange M. J. , Olsen G. H.
Published: July 2002

We have demonstrated a novel planar, avalanche photodiode (APD) for use in long-wavelength (0.95–1.65 μm) optical communication systems. The device is a separate absorption and multiplication region APD utilizing p+ guard rings which are concentric with, but not attached to the central diffused p+-n junction region. Since no contact is made to the rings, their potential is allowed to ‘‘float’’ at a value somewhat less than that established by the externally applied voltage. The APD, which is fabricated in a manner identical to simple p-i-n photodiodes, eliminates edge breakdown effects while greatly reducing the electric field at the insulator/semiconductor interface. A 60-μm-diam junction device grown by vapor phase epitaxy is observed to have a primary dark current of <300 pA, and a capacitance of 290 fF at 90% of the breakdown voltage. Uniform gains as high as 11 have been observed.
Room-temperature optically pumped Cd0.25Zn0.75Te/ZnTe quantum well lasers grown on GaAs substrates
Authors: Glass A. M. , Tai K. , Bylsma R. B. , Feldman R. D. , Olson D. H. , Austin R. F.
Published: July 2002

Optically pumped lasers emitting near 600 nm at room temperature have been fabricated for the first time in Cd0.25Zn0.75Te/ZnTe superlattices grown on GaAs substrates. The threshold pump intensity using pulsed 0.53 μm radiation increased from ∼7 kW/cm at 10 K to ∼60 kW/cm2 at room temperature with a threshold temperature dependence described by T0∼111 K.
Parametric study of AlAs/GaAs superlattice double-barrier diodes
Authors: Paulus M. J. , Bozada C. A. , Huang C. I. , Dudley S. C. , Evans K. R. , Stutz C. E. , Jones R. L. , Cheney M. E.
Published: July 2002

Quantum well diodes with barriers formed by thin, short-period binary AlAs/GaAs superlattices were fabricated and found to have very high peak-to-valley current ratios. The effects of varying the AlAs and GaAs layers in the barriers are studied. The peak current density is found to decrease by orders of magnitude for monolayer increases in the AlAs layer thicknesses. Tunneling current peaks due to both resonance levels in the quantum well and resonance levels in the superlattice barriers are observed.
GaAs/GaAlAs distributed Bragg reflector laser with a focused ion beam, low dose dopant implanted grating
Authors: Wu M. C. , Boenke M. M. , Wang S. , Clark W. M. , Stevens E. H. , Utlaut M. W.
Published: July 2002

We report for the first time, the performance of a GaAs/GaAlAs distributed Bragg reflector (DBR) laser using a focused ion beam implanted grating (FIB-DBR). Stripes of Si++ with a period of 2300 Å and a dose ∼1014 cm−2 are directly implanted into the passive large optical cavity layer to provide the distributed feedback. Surface-emitting light from the second-order grating is observed. Threshold current of 110 mA and single DBR mode operation from 20 to 40 °C are obtained. The wavelength tuning rate with temperature is 0.8 Å/°C. The coupling coefficient is estimated to be 15 cm−1. The results show that FIB technology is practical for distributed feedback and DBR lasers and optoelectronic integrated circuits.
Electrocontrolled beam coupling and bistable behavior in SBN:Ce crystals
Authors: Ma Jian , Liu Liren , Wu Shudong , Wang Zhijiang , Xu Liangying , Shu Biyun
Published: July 2002

We present the experimental result of electrocontrolled two-beam coupling in photorefractive SBN:Ce crystals. The coupling direction and coupling gain can be predetermined by an externally applied dc electric field, and the coupling gain shows a bistable behavior. A theoretical explanation is also given.
Optical phase conjugation using general self-pumped four-wave mixing
Authors: Wang Xiaochun , Zhang Yimo
Published: July 2002

We propose a general self-pumped four-wave mixing device in which the pump waves are derived from a single incident optical beam. In a single-mode fiber, only the fundamental mode of the fiber can propagate. The output of a single-mode fiber can provide pump waves of four-wave mixing. We have demonstrated that the phase distortion is eliminated by using this device.
Thermally induced metastability in amorphous silicon thin-film transistors
Authors: Lee Yi Sang , Chu Hye Yong , Jang Jin , Bae Byung Seong , Choi Kwang Soo , Lee Choochon
Published: July 2002

The effect of thermal quenching on the characteristics of hydrogenated amorphous silicon thin-film transistors using amorphous silicon nitride as a gate insulator has been studied. We find that rapid quenching produces changes in the field-effect conductance which are completely reversed by annealing. Rapid quenching produces a decrease in the off conductance and an increase of the on conductance. The decrease of the off conductance is due to the increase of the dangling bond density. On the other hand, the increase of the on conductance can be explained as either the decrease of the interface state density between amorphous silicon and the silicon nitride or the decrease in source series resistance by thermal quenching.
Gain dependence of the threshold characteristic temperature in multiple quantum well lasers
Authors: Wilcox J. Z. , Peterson G. L. , Ou S. S. , Yang J. J. , Jansen M. , Schechter D.
Published: July 2002

An analytical formula that determines dependence of the threshold characteristic temperature T0 on gain in multiple quantum well lasers is derived by approximately evaluating the gain integrals. Because the threshold gain depends on lasing cavity and quantum well structures, the formula determines dependence of T0 on laser length, reflectivities, optical loss, and number of quantum wells. A very good agreement is obtained between theory and experiment.
‘‘Bootstrap’’ loss mechanism for electromagnetic waves guided in a nominally loss-free nonlinear medium
Authors: Suhl H. , Vernon F. , Fenner W.
Published: July 2002

A self-consistent procedure is suggested, designed to calculate the power leakage out of dielectric waveguide with field-dependent dielectric constant. The method is to consider the guide, on the one hand, as a ‘‘black box’’ with an intrinsically lossy but linear medium and, on the other hand, as a guide with loss-free linear medium but containing a radiating current source composed of the nonlinear terms. Equating the results for the two alternative viewpoints gives the effective decay constant.
Free-electron cyclotron resonance lasers
Authors: Wang Changbiao
Published: July 2002

In this letter, we propose and analyze an oscillator configuration of a new laser, called free-electron cyclotron resonance laser, which basically converts synchrotron radiation to a coherent oscillation. In this laser, unlike the harmonic gyrotron based on the interaction of axially propagating electromagnetic wave with an electron beam, light wave propagates transverse to an electron beam. It is shown that the device can generate light output at a wavelength of 10.6 μm or shorter by the interaction of only about a 12 MeV electron beam with extremely high harmonics. Expressions for harmonic linear electron efficiency and start-up current are obtained.
Reversal of x-ray diffraction dislocation contrast in gallium arsenide
Authors: Paz O. , Goldsmith C. C. , Huber A.
Published: July 2002

We present x-ray topography and defect etching results, using a new etch that demonstrates that in GaAs, dislocations and regions decorated with etch pits correspond to low-intensity x-ray images. In silicon the opposite effect is observed and dislocations result in a high-intensity x-ray image. This reversal, due to an x-ray dispersion shift from the kinematical range to the dynamical range, is frequently overlooked. The defects investigated include grooves aligned along the [110] direction and decorated with etch pits, as well as etch pits distributed in a cellular structure, with a concentration that follows the W-shaped dislocation pattern.
Vanishing of superconductivity at a transition from itinerant-electron to small-polaron conduction in nominal Bi4−xPbx(Sr3Ca)Ca2−xYxCu4O16
Authors: Manthiram A. , Goodenough J. B.
Published: July 2002

Lead was found to substitute for bismuth on cosubstitution of yttrium for calcium in nominal Bi4(Sr3Ca)Ca2Cu4O16. Variations with x in the lattice parameters, the oxidation parameter determined by iodometric titration, and the temperature dependence of resistance have revealed a correlation of the variation of Tc and c parameter versus x with a metal-to-semiconductor transition. It is argued that this correlation manifests a transition from itinerant-electron to small-polaron conduction. This conclusion is related to the observed shifts in c-axis oxygen that appear to be associated with a transition from antiferromagnetic semiconductor to a superconductor in other copper-oxide systems.
Deep trench structures in silicon for sensitivity enhancement of Si/SiO2 interface studies
Authors: Stathis J. H. , Bassous E. , Scott B. A.
Published: July 2002

The measurement of defects at the silicon-insulator interface by most spectroscopic techniques is difficult because of their low concentration. A novel structure has been fabricated by etching a dense array of deep trenches through a silicon wafer. All the sidewalls in this structure are {111} surfaces, and the surface area is greatly enhanced compared to that of a polished wafer of equivalent size. We have grown an oxide on this structure and have achieved better than an order of magnitude increase in the sensitivity of electron paramagnetic resonance measurements of Pb defects at the SiO2-Si(111) interface.
Superconducting coatings in the system Bi-Ca-Sr-Cu-O prepared by plasma spraying
Authors: Asthana A. , Han P. D. , Falter L. M. , Payne D. A. , Hilton G. C. , Van Harlingen D. J.
Published: July 2002

Superconducting coatings in the system Bi-Ca-Sr-Cu-O were deposited on alumina substrates by plasma spray methods. The coatings were superconducting in the ‘‘as-sprayed’’ condition and improved with heat treatment. The best results were for coatings with resistivity values near 10 mΩ cm at room temperature and zero resistance at 96 K. The coatings had a magnetic transition near 80 K, with a weak diamagnetic signal up to 112 K. Superconductivity in the coatings was associated with two distinct phases, one of which was not identified. Scanning electron microscopy, x-ray diffraction, electrical resistivity, and magnetic measurements were used to characterize the coatings.
Specular CuInSe2 films for solar cells
Authors: Birkmire R. W. , McCandless B. E.
Published: July 2002

Specular CuInSe2 films suitable for solar cell devices have been produced by etching the as-deposited films in an aqueous bromine solution. Structural analysis and device results indicate that the CuInSe2 films are compositionally and electronically homogeneous even though the films are deposited in two distinct layers. The implications for improvements in CuInSe2 cell and module performance are discussed.
Recrystallization of AlNx (x<1) thin films induced by N implantation
Authors: Kobayashi K. , Namba S. , Fujihana T. , Kobayashi T. , Dai Y. , Iwaki M.
Published: July 2002

The effect of ion implantation on recrystallization of films has been investigated using AlNx (x<1) films as targets. The 750 Å AlNx (x<1) films were deposited on Si(111), glassy carbon, and commercial glass by an activated reactive evaporation method in a nitrogen atmosphere. The 80 keV N+ implantations were carried out near room temperature with doses ranging from 5×1016 to 5×1017 N+ions/cm2 at 1×10−6 Torr. The x-ray diffraction patterns revealed that N implantation enhances a (002) orientation of AlN, growth of which depends on doses. The optical transmittance of the AlNx films is also improved by N implantation, depending on doses. N implantation into AlNx (x<1) even without any annealing is effective for recrystallization of the films, which leads to improvement of optical properties.
Synthesis and properties of a 125 K superconductor in the Tl-Ca-Ba-Cu-O system
Authors: Gopalakrishnan I. K. , Sastry P. V. P. S. S. , Gangadharan K. , Phatak G. M. , Yakhmi J. V. , Iyer R. M.
Published: July 2002

A method for the synthesis of a 125 K superconducting phase having a nominal composition TlCaBaCu2 Ox is described. It is shown that by sintering at 1200 K in flowing oxygen containing a controlled amount of water vapor, a zero electrical resistance state (Tcf) at temperatures as high as 125 K can be obtained. A transport critical current density (Jc ) of ∼240 A/cm2 at 77 K was obtained in this 125 K material.
Dependence of T
c on hole concentration in the superconductors Bi4Sr3Ca3−xYxCu4O16+δ
Authors: Manthiram A. , Goodenough J. B.
Published: July 2002

Substitution of Y for Ca in the high Tc superconductor system Bi4Sr3Ca3−xYxCu4O16+δ (0≤x≤1.5) is accompanied by an increase in oxygen concentration δ≊0.34+0.3x that is insufficient to compensate for the increase in counter-cation valence. Nevertheless, Tc≊86 K remains nearly constant in the interval 0≤x≤0.5; it drops smoothly to zero in the interval 0.5<x≤1.15. Correlation of the compositional limit x=0.5 of the Tc plateau with the onset of trapping of holes could indicate that any oxygen atom in excess of O16.5 occupies a different crystallographic position where it traps two holes either as Bi5+ or as (O2)2−.
Two-dimensional superstructure in the (001) plane of Bi2[Ca,Sr]3Cu2O8+δ thin films
Authors: Marshall A. F. , Oh B. , Spielman S. , Lee Mark , Eom C. B. , Barton R. W. , Hammond R. H. , Kapitulnik A. , Beasley M. R. , Geballe T. H.
Published: July 2002

Thin films of Bi-Ca-Sr-Cu-O showing superconductivity above 100 K have been made by electron beam evaporation with oxygen post-annealing. The major superconducting phase, Bi2[Ca,Sr]3Cu2O8+δ (Tc ∼85 K), is oriented epitaxially with the (100)SrTiO3 substrate. In addition to the one-dimensional incommensurate superstructure along the b axis, which is characteristic of this phase, we have observed by transmission electron microscopy a two-dimensional incommensurate superstructure in the a-b plane with a different periodicity and a different orientation relationship to the subcell.
Superconducting yttrium-barium-copper-oxide ribbons fabricated from a metal alloy precursor
Authors: Pinkerton F. E. , Meisner G. P. , Fuerst C. D.
Published: July 2002

We report a new process for making superconducting Y-Ba-Cu-oxide ribbon from a ductile metal alloy precursor ribbon. We begin by melt-spinnng an alloy having the composition YCu3 to obtain the microcrystalline precursor ribbon. The ribbon is coated with a molten mixture of Ba inorganic compounds at 550 °C, and reacted in air at 925 °C to form the superconducting YBa2Cu3O7−x phase. The superconducting onset occurs at 92 K and zero resistance is reached at 89 K. X-ray diffraction, electron microscopy, and magnetization measurements confirm that the ribbon is predominantly superconducting YBa2Cu3O7−x.
Vacuum deposition of multilayer Bi-Ca-Sr-Cu-O superconducting thin films
Authors: Paserin V. , Rashti M. A. , Brodie D. E.
Published: July 2002

Superconducting Bi-Ca-Sr-Cu-O thin films were prepared by sequential evaporation of layers of Cu, Ca, Bi2O3, and Sr on single-crystal MgO substrates, followed by an anneal in an O2 atmosphere. An electron beam source was used for Sr and resistively heated sources for Cu, Ca, and Bi2O3. An onset transition temperature of around 80 K was observed with a resistance anomaly at 105 K. The film properties were found to be very sensitive to the anneal conditions. Samples were characterized by resistivity measurements, Auger spectroscopy, scanning electron microscopy, and energy dispersive x-ray microanalysis.
Low-temperature absorption steps near ultraviolet intrinsic edge in beta barium metaborate
Authors: Zhang Guangyin , Yang Yanrong , Zhang Chunping
Published: July 2002

This letter reports three new absorption steps appearing by the long wavelength side of the UV intrinsic absorption edge of β-BaB2O4 crystal at low temperature. We suggest that these new absorption steps should be attributed to the transitions of the indirect excitons bound in the centers of certain neutral impurities contained in the crystal specimens.
GaAs double quantum well laser diode with short-period (AlGaAs)m(GaAs)n superlattice barriers
Authors: Imamoto H. , Sato F. , Imanaka K. , Shimura M.
Published: July 2002

A short-period (AlGaAs)m(GaAs)n superlattice has been applied to the barrier layers in a single and a multiple quantum well structure prepared by molecular beam epitaxy in order to improve the interface quality. With a 38 Å thin GaAs quantum well without employing aluminum, a low threshold current density of 260 A/cm2, a high characteristic temperature (T0) of 205 K, and a high differential quantum efficiency of 75% have been achieved in a double quantum well ridge waveguide laser diode emitting at 780 nm.
Phase-locked operation of a three-element InGaAsP/InP grating-surface-emitting diode laser array
Authors: Palfrey S. L. , Hammer J. M. , Longeway P. A. , Carlson N. W. , Evans G. A. , Andrews J. T. , Jaklik J. , Kirk J. B. , Stolzenberger R. , Triano A. R.
Published: July 2002

Phased-locked operation of a three-element linear grating-surface-emitting laser diode array in the InGaAsP/InP material system is demonstrated. Far-field patterns and spectra indicate coherence across the length of the array and dynamic wavelength stability due to grating feedback.
Insight into the dynamics of trimethylaluminum photolysis
Authors: Higashi G. S. , Steigerwald M. L.
Published: July 2002

A b initio methods (Hartree–Fock, generalized valence bond, and configuration interaction) have been used to characterize the electronic states of molecular analogs to trimethylaluminum. An understanding of the mechanism of photoexcitation and subsequent dissociation emerges as the calculations reveal that optical excitation results in a metastable bound state rather than a directly dissociative state. The substantial excess energy associated with the transition is stored in electronic and vibrational degrees of freedom other than those associated with the dissociation coordinate. This interpretation allows a large body of observations to be simply understood and has implications for the implementation of the technology of laser photolysis for thin-film deposition.
Si particle density reduction in Si molecular beam epitaxy using a deflection electrode
Authors: Tatsumi Toru , Hirayama Hiroyuki , Aizaki Naoaki
Published: July 2002

The sticking of Si particles on the substrate surface is a serious problem for silicon molecular beam epitaxy (Si MBE) using an electron beam evaporator. We found that these particles were attracted to substrate surfaces on which a voltage was applied. Si particles were considered to have charges due to electron beam irradiation from a Si evaporator and to accelerate toward the substrate by Coulomb interaction. Because of this property, Si particles could be captured with a Ta electrode installed between an Si evaporator and the substrate. Si particle density decreased as electrode voltage increased and was unmeasurable when the electrode voltage went as far as +4 kV on the positive side and −6 kV on the negative. This technique can be applied to the particle contamination reduction not only in Si MBE but in all evaporation processes using an electron beam evaporator.
Doping Zn1−xMnxSe n type
Authors: Hong Run-Di , Dow John D.
Published: July 2002

The standard n-type dopant Ga is predicted to change its character from a shallow donor to a deep trap with increasing alloy composition x in Zn1−xMnxSe. As a result, Ga-doped Zn1−xMnxSe alloys should be n type for very small x, but not for Mn-rich material.
Experimental verification of frequency level-off of modulational instability in the minimum dispersion region
Authors: Ito Fumihiko , Kitayama Ken-ichi , Yoshinaga Hisao
Published: July 2002

It is verified experimentally that the modulation frequency of modulational instability (MI) levels off to a certain upper limit by the fourth-order dispersion of the optical fiber as the pump wavelength approaches the zero-dispersion wavelength in the anomalous spectral region. Modulation frequencies observed in optical fibers with various dispersion values range up to 7 THz for an input intensity of 15 W/70 μm2. This agrees well with the recently reported theoretical prediction based upon the four-photon mixing approach to MI.
Self-deformed and hysteretic photocurrent spectra of quantum wells with a load resistor
Authors: Tokuda Yasunori , Kanamoto Kyozo , Tsukada Noriaki
Published: July 2002

We report a study of the self-deformation of the photocurrent spectra of a quantum well p-i-n structure connecting with a high series resistor. The observed phenomena are interpreted in terms of the modulation of the internal electric field at the intrinsic quantum well region by the photocurrent itself. Furthermore, it is predicted and demonstrated that bistability of the photocurrent is achieved as a function of the wavelength.
Existence of interstitialcy Zn atoms in GaAs:Zn grown by the liquid-encapsulated Czochralski technique
Authors: Kitano T. , Watanabe H. , Matsui J.
Published: July 2002

Using the extended x-ray absorption fine structure method, we have studied the local structures around Zn atoms in Zn-doped GaAs crystal grown by the liquid-encapsulated Czochralski technique. Zn atoms, whose concentration is about 2.4×1018 cm−3, have the first nearest neighbor atoms at a very short distance of about 1.95 Å and the second nearest neighbor atoms at a distance of about 3.15 Å. The Zn atom configuration forms ‘‘interstitialcy’’, not substitutional, tetrahedral, or hexagonal sites. As the Zn concentration increases, however, Zn atoms have a tendency to occupy substitutional sites.
AlAs/GaAs tunnel emitter bipolar transistor
Authors: Levi A. F. J. , Nottenburg R. N. , Chen Y. K. , Cunningham J. E.
Published: July 2002

We report the first microwave AlAs/GaAs tunnel emitter bipolar transistor utilizing nonequilibrium electron transport in the base. At an emitter current density of 1×105 A cm−2, current gain of greater than unity is measured up to a frequency of 40 GHz. dc current gains of 82 and 53 are measured for devices with emitter stripe widths of 9 and 1.5 μm, respectively. Enhanced device scaling is made possible with the extremely high velocity in the thin base region.
Growth flux ratio dependence of microwave devices in molecular beam epitaxy
Authors: Chou Y. C. , Lee C. T. , Juang F. Y. , Chang C. C. , Chou K.
Published: July 2002

The effects of beam equivalent pressure ratio PAs4/PGa on electrical and microwave performance of GaAs low-noise metal-semiconductor field-effect transistors grown by molecular beam epitaxy were demonstrated. From experimental results, superior performances were achieved at the minimum beam equivalent pressure ratio of 30 under arsenic-stabilized condition. The optimum noise figure and its associated gain were attributed to the higher quality of the molecular beam epitaxial material at optimal growth conditions. An explanation of the experimental results was also proposed.
Dynamically programmable self-aligning optical interconnect with fan-out and fan-in using self-pumped phase conjugation
Authors: Cronin-Golomb Mark
Published: July 2002

A dynamically reprogrammable optical interconnect is demonstrated using temporally multiplexed writing beams in photorefractive double phase conjugation to achieve arbitrary fan-out and fan-in. Applications to neural networks and image transmission through thick distortions are discussed.
Improved attenuated total reflectance technique for the investigation of dielectric surfaces
Authors: Herminghaus S. , Leiderer P.
Published: July 2002

Guided wave surface polaritons (GWSPs) propagating in a dielectric slab adjacent to a metal surface are investigated both theoretically and experimentally. It is shown that GWSPs can be used for high-resolution analysis of dielectric surfaces by means of the well-known attenuated total reflectance technique. From our experimental results we conclude that changes in the system equivalent to the adsorption of 1/30 of a monolayer can easily be resolved. A well-established surface characterization method, which had been restricted to few systems up to now, is thus immensely generalized.
Triethylgallium adsorption on Si(100) and Si(111) surfaces
Authors: Hirayama Hiroyuki , Sasaoka Chiaki , Tatsumi Toru , Ohshita Yoshio
Published: July 2002

Triethylgallium (TEG) adsorption on Si(100) 2×1 and Si(111) 7×7 surfaces was studied by reflection high-energy electron diffraction (RHEED) and x-ray photoelectron spectroscopy (XPS). At room temperature, TEG molecules nondissociatively adsorbed on Si surface. Being judged from the Ga 2P3/2 and C 1s peak height, TEG molecules dissociatively adsorbed and Ga was selectively deposited on Si surfaces at temperatures between 200 and 500 °C. At temperatures above 500 °C, Ga thermal desorption was observed. RHEED pattern showed the β-SiC growth in this temperature range. Temperature dependence of the Ga 2P3/2 peak at Si(100) was different from that at Si(111), which strongly suggests that the surface dangling bond plays an important role in TEG dissociative adsorption.
Spectroscopic investigation of oxide states responsible for hot-carrier degradation
Authors: Weber W. , Brox M. , Hofmann F. , Huber H. , Jäger D. , Rieger D.
Published: July 2002

Hole-trap states in the gate oxide of a Si metal-oxide-semiconductor field-effect transistor (MOSFET) are investigated by inhomogeneous excimer laser irradiation. Subbandgap ultraviolet light photons with an energy exceeding a threshold lying between 5.5 and 6.4 eV were found to excite electrons from these originally neutral states into the SiO2 conduction band. A fixed positive charge is left behind. The degradation in MOSFET performance due to the irradiation is comparable to that accompanying hot-hole injection. Also, subsequent hot-electron stress changes the device characteristics in a way similar to hot-electron stress following hot-hole stress. It is concluded that the traps responsible for hot-carrier degradation cause the optically induced charge trapping.
Electron velocity overshoot and valley repopulation effects in diamond
Authors: Osman M. A. , Grubin H. L. , Kreskovsky J. P.
Published: July 2002

Using ensemble Monte Carlo procedures, electron velocity overshoot and transient valley repopulation in diamond have been investigated as a function of field strength and orientation. It is found that the response of electrons to the sudden application of a 50 kV/cm electric field along 〈100〉 results in a velocity transient with a maximum of 1.9×107 cm/s after 200 fs and a steady state value of 1.30×107 cm/s. For a field along 〈110〉, the corresponding maximum and steady state values are 2.0×107 and 1.4×107 cm/s, respectively. The calculated temporal and spatial duration of velocity overshoot in diamond is longer than that of silicon but shorter than that of gallium arsenide.
Observation of capacitive modulation of bipolar current in crystalline silicon gated p-i-n structures
Authors: Sun C. C. , Xu J. M.
Published: July 2002

We report, for the first time, the experimental observation of capacitive modulation of bipolar current in crystalline silicon devices consisting of a lateral p-i-n channel and an insulated polycrystalline silicon gate. Modulation characteristics of devices with different channel lengths are compared.
Anomalous diffusion of nitrogen in nitrogen-implanted silicon
Authors: Hockett R. S.
Published: July 2002

A secondary-ion mass spectrometry analysis of the coimplantation of nitrogen, carbon, and oxygen into float-zone silicon followed by rapid thermal annealing for 10 s at different temperatures is used to study the anomalous diffusion behavior of nitrogen in silicon. The results may be only partially explained by a model of paired nitrogen atom diffusion. The complexity of the diffusion of nitrogen in ion-implanted samples, with and without coimplants, and the expectation that the nitrogen after annealing may be in many different forms, suggest that studies which use nitrogen implantation for basic understanding of nitrogen-related defects may be misleading.
High-power, diffraction-limited, narrow-band, external-cavity diode laser
Authors: Sharfin W. F. , Seppala J. , Mooradian A. , Soltz B. A. , Waters R. G. , Vollmer B. J. , Bystrom K. J.
Published: July 2002

We demonstrate an external-cavity GaAs/GaAlAs single quantum well diode laser that produces 1.6 W of cw power with 32% overall efficiency in a spectral band of 0.02 nm. Over 0.1 W is measured in a single-frequency, diffraction-limited beam.
Observation of apparent inelastic tunneling between Landau levels in superlattices
Authors: Higman T. K. , Favaro M. E. , Miller L. M. , Emanuel M. A. , Coleman J. J.
Published: July 2002

Evidence of the elastic and inelastic components of sequential resonant tunneling in AlAs/GaAs superlattices is presented. Magnetic field data (B parallel to current flow) show that as the energy spacing between the Landau levels in the quantum wells is changed, the corresponding density of states available for tunneling via inelastic scattering paths is changed and thus the magnetic field influences the inelastic portion of the current.
Threshold power density for photodecomposition of nitrocellulose
Authors: Ye Yutang , Hunsperger Robert G.
Published: July 2002

The threshold power density for photodecomposition of nitrocellulose varies greatly with the irradiation mode and an interpretation of that fact is presented. The threshold conditions for different irradiation modes are described.