bluuebunny/crossref_metadata_2025 huggingface dataset:
Mindfulness-based Therapies and Cancer-related Fatigue: A Narrative Review
Authors: G. Deeksha Shenoy , Alva Rashmitha , Nair Abhishek Ravi
Published: February 2025

Globally, the prevalence of cancer is steadily increasing, making it the second most common cause of death from non-communicable diseases, after cardiovascular disorders. It represents the highest rates of morbidity and mortality, and its prevalence continues to rise. Despite significant advancements in treatments, most cancer therapies are associated with both immediate and long-term side effects, including nausea, fatigue, appetite loss, hair loss, pain, and others. One of the most common and debilitating symptoms is Cancer-Related Fatigue (CRF). According to the European Association of Palliative Care, fatigue is "a subjective feeling of tiredness, weakness, or lack of energy." CRF can develop at any stage of the illness and may persist for years after treatment. The primary objective of this review is to explore the impact of mindfulness-based therapies in managing CRF. Integrative oncology, combining conventional therapies with evidence-based Complementary and Alternative Medicine (CAM) practices, offers a holistic, patient-centered approach to CRF management. This includes mindfulness-based and biobehavioural therapies, such as yoga and meditation. This review aims to examine the research on the successful application of mindfulness techniques to effectively address CRF, offering insights for improving patient care and quality of life.
In vitro Anticancer and Antioxidative Potential of Nyctanthes arbor-tristis Linn Aqueous Leaves Extract
Authors: Singh Himani , Ambwani Sonu , Ambwani Tanuj Kumar
Published: February 2025

Nyctanthes arbor-tristis is a medicinal plant used to treat various inflammation-associated ailments, cancer and to combat innumerable infections in the traditional system of medicine. The current study’s goal was to investigate the antioxidative and anticancer properties of the aqueous leaves extract of Nyctanthes arbor-tristis (NAE). The leaves of Nyctanthes arbor-tristis were collected from CSIR- CIMAP Research Centre, Pantnagar, Uttarakhand. To examine the antioxidant activity of NAE two different approaches were followed. The aqueous leaves extract showed marked antioxidant potential determined by total antioxidant capacity and reducing power. NAE showed a notable total antioxidant capacity of 235.67 mg of ascorbic acid equivalents per g of extract. The reducing power increased with the increment in the concentration of NAE, ranging from 0.063 at 20μg/mL to 0.388 at 200μg/mL. MTT assay was investigated against HepG2 cell line. High level of resistance to HepG2 liver cancer cell lines was noted with NAE with MNCD value of 10μg/mL. The results obtained highlighted the importance of extracts from Nyctanthes arbor-tristis and suggested the use of chemotherapeutic drugs to treat tumours in the future.
Effects of Calcium Nitrate Application on Essential Soil Properties in Apple Plantation Grown under High Density Planting System
Authors: Mir Lareb , Sheikh Yawer Ahmad , Kumar Raju , Shahnaz Efath , Ahmed Sohail , Butt Idrees Ashraf , Abrol Sonal , Aezum Mujtaba , Dar Shahnawaz Rasool
Published: February 2025

Calcium is an important mineral needed in the soil for the production of good quality apples. The investigation aimed to study effect of calcium nitrate soil application on some post-harvest soil properties in an apple plantation. Calcium nitrate soil application at the rate of 0 (control), 100, 200 and 300 gram per plant in two apple varieties Golden Delicious and Red Chief Camspur comprising 8 treatments with three replications were tested. Soil application of calcium nitrate increased organic carbon, cation exchange capacity, nitrogen, potassium and calcium availability with every enhanced dose in post-harvest soil, whereas available phosphorous, iron, zinc and boron with every enhanced dosage of calcium nitrate showed opposite trend and reduced availability of these nutrients in post-harvest soil. Soil organic carbon ranged from (0.788 to 0.852 %), CEC ranged from (15.0 to 18.0 cmol kg-1), Available N ranged from (258.5 to 268.1 kg ha-1), available P ranged from (14.78 to 16.29 kg ha-1), available K ranged from (303.7 to 310.7 kg ha-1), available Ca ranged from (1276.5 to 1370.3 ppm), Fe ranged from (43.778 to 47.552 ppm), available Zn ranged from (1.267 to 1.183 ppm), available boron ranged from (0.895 to 1.045 ppm). Among doses calcium nitrate soil application @ 300 gram per plant was superior to 200 or 100 gram per plant in both apple varieties. Golden Delicious performed better than Red Chief Camspur but variation was statistically non-significant. Results of research evidenced that calcium nitrate application reduced availability of soil phosphorous and micronutrients, thus mixture of micronutrients must be recommended to maintain availability of these elements to apple plant. Further studies under different ecologies and soil category need to be carried for finding threshold limits of calcium dosage as per plant establishment, moisture variability and plant age.
Influence of Substrate Composition on Growth, Yield and Antimicrobial Activity of Pleurotus djamor
Authors: Mathavan M. , Rajadurai S. , Gomathy M. , Babu R. Santhosh , Raja A. Ajay
Published: February 2025

Aims: This study investigates the cultivation and biological efficacy of Pleurotus djamor var. roseus, commonly known as the pink oyster mushroom, using low-cost techniques and various agro-wastes as substrates. With global mushroom production exceeding two million tons annually, the economic and nutritional importance of mushrooms has been recognized, particularly due to their high protein, fiber content and antioxidant properties.
Study Design and Methodology:  The research involved preparing a suitable substrates, including the sterilization and spawning of paddy straw, followed by monitoring growth parameters such as spawn running, pinhead formation, and fruit body development.
Place and Duration of Study: The study was conducted at Department of Microbiology, Kamarajar Government Arts College, Surandai.
Results: The results indicate optimal conditions for mycelial growth and yield, with a biological efficiency of 43% observed in paddy straw substrates. Additionally, the ethanolic extracts of P. djamor were tested for antibacterial activity against both gram-positive and gram-negative pathogens, showing significant inhibitory effects, particularly against Escherichia coli and Pseudomonas aeruginosa.
Conclusion: The results indicate that *P. djamor* var. *roseus* is a nutrient-dense mushroom with potential health benefits, making it a valuable addition to diets aimed at addressing chronic diseases and aging. This research underscores the benefits of using agricultural waste for sustainable mushroom cultivation while highlighting the health-enhancing properties of this species.
Expression of an active adenylate‐forming domain of peptide synthetases corresponding to acyl‐CoA‐synthetases
Authors: Dieckmann Ralf , Lee Yoen-Ok , van Liempt Henk , von Döhren Hans , Kleinkauf Horst
Published: July 2002

Peptide synthetases and acyl‐CoA‐synthetases form acyl adenylates which are transferred to CoA or enzyme‐bound pantetheine. To verify the existence of an adenylate domain in peptide synthetases, a 60.8 kDa fragment of tyrocidine 1‐synthetase was constructed by a 1629 bp deletion, expressed in Escherichia coli, and characterized. The truncated multienzyme activated phenylalanine and substrate analogues with comparable kinetics as the over‐expressed synthetase, as judged by ATP‐[32P]PPi exchange reaction. Thus the N‐terminal domain resembling an acyl‐CoA‐synthetase is an autonomous structural element. This N‐terminal domain is followed by a cofactor binding domain, resembling acyl carrier proteins involved in polyketide formation.
Cellular glucose‐6‐phosphate dehydrogenase (G6PD) status modulates the effects of nitric oxide (NO) on human foreskin fibroblasts
Authors: Cheng Mei-ling , Ho Hung-yao , Liang Chi-ming , Chou Yi-hung , Stern Arnold , Lu Fung-jou , Chiu Daniel Tsun-yee
Published: July 2002

Glucose‐6‐phosphate dehydrogenase (G6PD) plays an important role in cellular redox homeostasis, which is crucial for cell survival. In the present study, we found that G6PD status determines the response of cells exposed to nitric oxide (NO) donor. Treatment with NO donor, sodium nitroprusside (SNP), caused apoptosis in G6PD‐deficient human foreskin fibroblasts (HFF1), whereas it was growth stimulatory in the normal counterpart (HFF3). Such effects were abolished by NO scavengers like hemoglobin. Ectopic expression of G6PD in HFF1 cells switched the cellular response to NO from apoptosis to growth stimulation. Experiments with 1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one and 8‐bromo‐cGMP showed that the effects of NO on HFF1 and HFF3 cells were independent of cGMP signalling pathway. Intriguingly, trolox prevented the SNP‐induced apoptosis in HFF1 cells. These data demonstrate that G6PD plays a critical role in regulation of cell growth and survival.
Regulation of UDP‐glucose:ceramide glucosyltransferase‐1 by ceramide
Authors: Komori Hironobu , Ichikawa Shinichi , Hirabayashi Yoshio , Ito Makoto
Published: July 2002

We report that the expression of mRNA and the activity of UDP‐glucose:ceramide (Cer) glucosyltransferase‐1 (GlcT‐1) of human hepatoma Huh7 and mouse melanoma B16 cells increases after treatment with bacterial sphingomyelinase or upon addition of short‐chain Cer. Interestingly, however, GlcT‐1 gene transcription was not increased by Cer when GlcT‐1 cDNA was introduced with the CMV promoter in GlcT‐1‐deficient GM95 cells, suggesting that the normal promoter region of GlcT‐1 gene is essential for the response. The conversion of C6‐Cer to C6‐GlcCer occurred much more rapidly in GlcT‐1‐overexpressing Huh7 cells than in mock transfectants. As a result, GlcT‐1‐overexpressing cells acquired a greater resistance to C6‐Cer‐mediated cell death.
Protein misfolding and disease; protein refolding and therapy
Authors: Soto Claudio
Published: July 2002

Diverse human disorders, including several neurodegenerative diseases and systemic amyloidosis, are thought to arise from the misfolding and aggregation of an underlying protein. Recent findings strongly support this hypothesis and have increased our understanding of the molecular mechanism of protein conformational disorders. Many questions are still pending, but the data overall suggest that correction of protein misfolding constitutes a viable therapeutic strategy for conformational diseases.
Effects of Pressing Lignocellulosic Biomass on Sugar Yield in Two‐Stage Dilute‐Acid Hydrolysis Process
Authors: Kim Kyoung Heon , Tucker Melvin P. , Nguyen Quang A.
Published: July 2002

Dilute sulfuric acid catalyzed hydrolysis of biomass such as wood chips often involves pressing the wood particles in a dewatering step (e.g., after acid impregnation) or in compression screw feeders commonly used in continuous hydrolysis reactors. This study addresses the effects of pressing biomass feedstocks using a hydraulic press on soluble sugar yield obtained from two‐stage dilute‐acid hydrolysis of softwood. The pressed acid‐impregnated feedstock gave significantly lower soluble sugar yields than the never‐pressed (i.e., partially air‐dried or filtered) feedstock. Pressing acid‐impregnated feedstocks before pretreatment resulted in a soluble hemicellulosic sugar yield of 76.9% from first‐stage hydrolysis and a soluble glucose yield of 33.7% from second‐stage hydrolysis. The dilute‐acid hydrolysis of partially air‐dried feedstocks having total solids and acid concentrations similar to those of pressed feedstocks gave yields of 87.0% hemicellulosic sugar and 46.9% glucose in the first and second stages, respectively. Microscopic examination of wood structures showed that pressing acid‐impregnated wood chips from 34 to 54% total solids (TS) did not cause the wood structure to collapse. However, pressing first‐stage pretreated wood chips (i.e., feedstock for second‐stage hydrolysis) from approximately 30 to 43% TS caused the porous wood matrix to almost completely collapse. It is hypothesized that pressing alters the wood structure and distribution of acid within the cell cavities, leading to uneven heat and mass transfer during pretreatment using direct steam injection. Consequently, lower hydrolysis yield of soluble sugars results. Dewatering of corn stover by pressing did not impact negatively on the sugar yield from single‐stage dilute‐acid pretreatment.
High levels of urinary eosinophil protein X in young asthmatic children predict persistent atopic asthma
Authors: Øymar Knut
Published: July 2002

Levels of urinary eosinophil protein X (U‐EPX) and eosinophil counts were measured in 32 children (12–36 months of age) who were hospitalized for acute asthma, and the U‐EPX levels were measured in 20 healthy children of the same age. The ability of these parameters to predict persistent asthma (at least one wheezing episode during the last 6 months) and atopic asthma (a positive skin‐prick test [SPT]), was evaluated at a follow‐up 2 years later. On admission, levels of U‐EPX were higher in children with asthma (median: 120 µg/mmol of creatinine; quartiles: 67–123 µg/mmol of creatinine) than in controls (60 µg/mmol of creatinine, 38–74 µg/mmol of creatinine; p< 0.001). The U‐EPX level was higher in those with persistent atopic asthma at follow‐up (173 µg/mmol of creatinine, 123–196 µg/mmol of creatinine, n = 16), than in those with persistent non‐atopic asthma (73 µg/mmol creatinine, 46–105 µg/mmol of creatinine, n = 8; p< 0.05), and higher than in those with transient asthma (no symptoms at follow‐up) (106 µg/mmol creatinine; 42–167 µg/mmol of creatinine, n = 8; p< 0.05). By multiple logistic regression analysis, U‐EPX was the only parameter able to predict persistent atopic asthma; eosinophil counts, parental atopy, age or gender could not. Parental atopy was the only parameter predictive for persistent asthma, regardless of atopic status. In conclusion, levels of U‐EPX, but not eosinophil counts, measured in young children hospitalized with acute asthma can predict the persistence of atopic asthma 2 years later.
Structure–function analysis of yeast piD261/Bud32, an atypical protein kinase essential for normal cell life
Authors: FACCHIN Sonia , LOPREIATO Raffaele , STOCCHETTO Silvia , ARRIGONI Giorgio , CESARO Luca , MARIN Oriano , CARIGNANI Giovanna , PINNA Lorenzo A.
Published: July 2002

The Saccharomyces cerevisiae YGR262c/BUD32 gene, whose disruption causes a severe pleiotropic phenotype, encodes a 261-residue putative protein kinase, piD261, whose structural homologues have been identified in a variety of organisms, including humans, and whose function is unknown. We have demonstrated previously that piD261, expressed in Escherichia coli as a recombinant protein, is a Ser/Thr kinase, as judged by its ability to autophosphorylate and to phosphorylate casein. Here we describe a mutational analysis showing that, despite low sequence similarity, the invariant residues representing the signature of protein kinases are conserved in piD261 and in its structural homologues, but are embedded in an altered context, suggestive of unique mechanistic properties. Especially noteworthy are: (i) three unique inserts of unknown function within the N-terminal lobe, (ii) the lack of a lysyl residue which in all other Ser/Thr kinases participates in the catalytic event by interacting with the transferred ATP γ-phosphate, and which in piD261 is replaced by a threonine, and (iii) an exceedingly short activation loop including two serines, Ser-187 and Ser-189, whose autophosphorylation accounts for the appearance of an upshifted band upon SDS/PAGE. A mutant in which these serines are replaced by alanines was devoid of the upshifted band and displayed reduced catalytic activity. This would include piD261 in the category of protein kinases activated by phosphorylation, although it lacks the RD (Arg-Asp) motif which is typical of these enzymes.
Interaction of oestrogen and peroxisome proliferator-activated receptors with apolipoprotein(a) gene enhancers
Authors: PUCKEY Loretto H. , KNIGHT Brian L.
Published: July 2002

A high plasma concentration of lipoprotein(a) [Lp(a)] confers an increased risk for the development of coronary heart disease. Hormones, such as oestrogen, are some of the few compounds known to reduce plasma Lp(a) levels. A putative enhancer region, located at the DHII DNase I hypersensitive site approx. 28kb upstream of the apolipoprotein(a) [apo(a)] gene, contains a number of sequences similar to the binding half-sites for nuclear hormone receptors, such as the oestrogen receptor and the peroxisome proliferator-activated receptor (PPAR). The 180bp core DHII enhancer increased the activity of the apo(a) promoter by over 7-fold in reporter-gene assays in HepG2 cells in vitro. Almost 60% of this increase was lost in the presence of co-transfected oestrogen receptor and oestrogen. In contrast, co-transfection with PPARα increased the effect of the DHII enhancer on apo(a) transcriptional activity by approx. 70% and could overcome the inhibitory effect of the oestrogen receptor on apo(a) transcription. Gel mobility-shift assays showed that oestrogen receptor protein bound to one half of a sequence corresponding to a predicted oestrogen receptor response element. PPARα also bound to this site and competed with oestrogen receptors for binding. In addition, PPARα bound to a separate site that comprised part of a direct repeat of nuclear hormone receptor half-sites. The results suggest that nuclear hormones affect plasma Lp(a) concentrations by binding to the sequences within the DHII enhancer, thereby altering the amount by which the enhancer increases the transcription of the apo(a) gene.
The outcome of varicocelectomy in subfertile men with an absent or atrophic right testis
Authors: AŞci  , Sarikaya Ş. , BÜYÜkalpelli  , Yilmaz  , Yildiz
Published: July 2002

Objectives

 To determine the effects of varicocelectomy on semen quality, testicular volumes and serum hormone levels in subfertile men with an absent or atrophic right testis.

Patients and methods

 Seventeen patients whose wives were gynaecologically normal were evaluated with at least two semen analyses and measurements of serum hormone levels and antisperm antibodies. Scrotal ultrasonography was used to determine testicular volumes and spermatic vein diameters. Varicocelectomy was performed by high ligation via an inguinal approach. All patients were seen at a follow‐up 3 months later, and after 6, 9 and 12 months the scrotal ultrasonography, hormone assessment and semen analyses were repeated. Any pregnancies in their wives were recorded over a median follow‐up of 19 months.

Results

 After surgery, all patients had significant improvements in sperm motility, morphology and concentration (P<0.01) but the differences in pre‐ and post‐operative testicular volumes and plasma hormone levels were not statistically significant (P>0.01). No patients had immunological infertility. Eleven of the wives became pregnant during the follow‐up.

Conclusion

 Higher pregnancy rates can be achieved by left varicocelectomy in subfertile men with an absent or atrophic right testis. Sperm concentration, motility and morphology are significantly improved by varicocelectomy.
Functional Characterization of the Amanita muscaria Monosaccharide Transporter, AmMst1
Authors: Wiese J. , Kleber R. , Hampp R. , Nehls U.
Published: July 2002

Abstract: Fungal carbohydrate nutrition is an important aspect of ectomycorrhizal symbiosis. At the plant/fungus interface, fungal and root cortical cells compete for monosaccharides, generated from plant‐derived sucrose. Therefore, the kinetic properties of the monosaccharide uptake systems are decisive for the monosaccharide yield of each partner. For the functional characterization of a hexose transporter (AmMst1) of the ectomycorrhizal fungus Amanita muscaria, the entire cDNA was expressed in a Saccharomyces cerevisiae strain unable to take up hexoses. Uptake experiments with 14C‐labelled monosaccharides resulted in KM values of 0.46 mM for glucose and 4.20 mM for fructose, revealing a strong preference of AmMst1 for glucose as substrate. Glucose uptake by AmMst1 was strongly favoured even in the presence of a large excess of fructose. Comparable affinities of AmMst1 for glucose, 3‐O‐methyl glucose and mannose were obtained. In contrast, AmMst1 imported galactose with a much lower efficiency, revealing that this transporter distinguishes pyranoses by steric hindrance at the C‐4 position. While yeast contains numerous hexose transporter genes, the AmMst1 gene seems to be the main, if not the only, hexose transporter that is expressed in A. muscaria, as concluded from the comparison of hexose import properties of A. muscaria protoplasts and AmMst1 expressed in yeast.
Self-consistency and self-sufficiency of the photocarrier grating technique
Authors: Balberg I. , Delahoy A. E. , Weakliem H. A.
Published: July 2002

The recently suggested photocarrier grating technique appears to be the most reliable method available for the determination of the ambipolar diffusion length in hydrogenated amorphous silicon. We show that the technique can be made simpler than originally suggested, and that it is self-sufficient in the sense that all the required parameters can be determined by the same experimental setup. It is demonstrated that the various results obtained by the technique are self-consistent and that extremely accurate values of the ambipolar diffusion length can be determined.
Intervalley scattering rates in GaAs measured by time-resolved four-wave mixing spectroscopy
Authors: Katz A. , Alfano R. R.
Published: July 2002

A three-pulse transient grating technique was used to measure the carrier dynamics in photoexcited GaAs. The four-wave mixing signal exhibits a two component relaxation of different magnitudes for various probe energies. The fast relaxation mechanism is due to electrons in the L valleys scattering back to the Γ valley. The effective transfer time for L→Γ was found to be ≊8 ps. The slower relaxation arises from carrier recombination.
Heteroepitaxy of InSb on silicon by metalorganic magnetron sputtering
Authors: Rao T. Sudersena , Webb J. B. , Houghton D. C. , Baribeau J. M. , Moore W. T. , Noad J. P.
Published: July 2002

Heteroepitaxial films of InSb have been deposited by metalorganic magnetron sputtering (MOMS) on 〈100〉 silicon substrates using molecular beam epitaxy (MBE) GaAs buffer layers. X-ray diffraction and cross-sectional transmission electron microscopy measurements indicate the epilayers to be structurally similar to layers deposited by MOMS and MBE on high quality GaAs substrates, despite the increased defect density of the GaAs buffer layer. Some of the defects within the buffer layer propagate into the InSb epilayer; however, the majority of defects arise from the lattice mismatch at the interfacial region.
Minority-carrier properties of GaAs on silicon
Authors: Ahrenkiel R. K. , Al-Jassim M. M. , Dunlavy D. J. , Jones K. M. , Vernon S. M. , Tobin S. P. , Haven V. E.
Published: July 2002

The minority-carrier lifetimes of the heteroepitaxial system of GaAs on Si are limited by recombination at mismatch dislocations. Here we show that increasing the thickness of the buffer layer, with an additional annealing step, reduces the dislocation density by about an order of magnitude. At the same time, the minority-carrier lifetime in these double heterostructures increases more than an order of magnitude.
InP:Yb layers grown by adduct metalorganic vapor phase epitaxy using Yb(M
e
C
p)3
Authors: Weber J. , Molassioti A. , Moser M. , Stapor A. , Scholz F. , Hörcher G. , Forchel A. , Hammel A. , Laube G. , Weidlein J.
Published: July 2002

Highly doped InP:Yb layers have been grown by adduct metalorganic vapor phase epitaxy at atmospheric pressure. Yb(MeCp)3, where Me=CH3 and Cp=n5-C5H5, was synthesized as Yb source material because of its relatively high vapor pressure at acceptable source temperatures. The layers were grown in a wide range of growth temperatures (560–670 °C) and Yb mole fractions (10−9–10−7). In photoluminescence experiments they showed strong Yb3+-4f emission. The layers were further characterized by Hall measurements and secondary-ion mass spectroscopy. In order to obtain n-type InP:Yb samples with high carrier concentrations we have grown InP layers double doped with S and Yb.
Spiral hollow cathode plasma-assisted diamond deposition
Authors: Tzeng Y. , Kung P. J. , Zee R. , Legg K. , Solnick-Legg H. , Burns D. , Loo B. H.
Published: July 2002

High quality diamond films have been deposited on silicon and sapphire by means of a combined hot filament/electron beam/plasma-assisted chemical vapor deposition technique. A spiral tantalum foil is used as the hot cathode to generate a high-current dc discharge at a low sustaining voltage. Gas mixtures consisting of methane, hydrogen, and argon flowing through the spiral cathode towards the anode are effectively decomposed by the hot cathode and the high-density plasma. Diamond particles and films, grown at a rate between 0.5 and 5 μm/h, have been characterized by scanning electron microscopy, x-ray diffraction, and Raman spectroscopy.
Hydrogen incorporation in silicon (oxy)nitride thin films
Authors: Kuiper A. E. T. , Willemsen M. F. C. , van IJzendoorn L. J.
Published: July 2002

Hydrogen in low-pressure chemical vapor deposited oxynitride films was measured using elastic recoil detection with 2 MeV He ions. A distinction between N- and Si-bonded hydrogen could be made for films deposited from ND3 instead of NH3. The analyses reveal that on an average three times as much hydrogen is incorporated as NH relative to SiH, and that a maximum in this ratio is present in oxynitride with a composition around O/N=0.3. This optimum coincides with a maximum in total hydrogen content in the film of 3.2 at. %. Hydrogen desorption occurs in a narrow temperature interval around 950 °C and proceeds virtually in an identical way for both binding types.
Spectral linewidth reduction in metalorganic vapor phase epitaxy grown 1.5 μm separate-confinement-heterostructure quantum well distributed feedback laser diodes
Authors: Takano Shinji , Sasaki Tatsuya , Yamada Hirohito , Kitamura Mitsuhiro , Mito Ikuo
Published: July 2002

Spectral linewidth reduction in 1.5 μm InGaAs/InGaAsP separate-confinement-heterostructure quantum well distributed feedback laser diodes (SCH-QW-DFB LD’s) is achieved for the first time. A 2.0 MHz minimum linewidth and a 5 MHz mW minimum linewidth power product are obtained.
Thin-film high T
c superconductors prepared by a simple flash evaporation technique
Authors: Osofsky M. S. , Lubitz P. , Harford M. Z. , Singh A. K. , Qadri S. B. , Skelton E. F. , Elam W. T. , Soulen R. J. , Lechter W. L. , Wolf S. A.
Published: July 2002

Thin films of Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O have been deposited on single-crystal MgO substrates by a simple flash evaporation technique. Small pellets of the superconducting compound were formed by standard techniques, then evaporated to completion on the MgO substrates using an electron beam. The best films show an onset of superconductivity at approximately 110 K and zero resistance by 78 K. X-ray diffraction measurements show the films to be tetragonal with nominal lattice parameters of a=3.85 Å and c=30.66 Å. The x-ray data also show the films to be highly textured with the metal-oxide planes parallel to the substrate surface.
Preparation of superconducting thin films of bismuth strontium calcium copper oxides by reactive sputtering
Authors: Face D. W. , Neal M. J. , Matthiesen M. M. , Kucera J. T. , Crain J. , Graybeal J. M. , Orlando T. P. , Rudman D. A.
Published: July 2002

Superconducting thin films of Bi-Sr-Ca-Cu-oxides have been reproducibly prepared by reactive magnetically enhanced triode sputtering using three separate metal targets (Sr, Ca, and Cu-Bi). Oxygen was introduced directly at the substrates during film growth. The films were deposited on ambient temperature substrates [Al2O3, SrTiO3, and yttria-stabilized zirconia (YSZ)] and had thicknesses of 0.5–1.5 μm. After deposition, the films were annealed at 850–900 °C in flowing oxygen. The electrical resistance of the best films on YSZ decreased approximately linearly with temperature until the onset of superconductivity at about 85 K. Zero resistance was achieved by 74 K. Critical current densities in excess of 5×105 A/cm2 at 4.2 K were also obtained. X-ray diffraction demonstrated that the best films were nearly single phase (Bi2Sr2Ca1Cu2O8+x) and textured with the c axis perpendicular to the substrate. The effect of composition and annealing on our results is discussed.
Photoconductance measurements on InAs0.22Sb0.78/GaAs grown using molecular beam epitaxy
Authors: Bethea C. G. , Levine B. F. , Yen M. Y. , Cho A. Y.
Published: July 2002

We report the molecular beam epitaxial growth of InAs0.22Sb0.78 on semi-insulating GaAs substrates, and the fabrication and characterization of photoconductance detectors.
Structure and composition of the 115 K superconducting phase in the Bi-Ca-Sr-Cu-O system
Authors: Ramesh R. , Thomas G. , Green S. M. , Rudee M. L. , Luo H. L.
Published: July 2002

Results of convergent beam electron diffraction and energy dispersive x-ray (EDX) microanalysis of Bi1.2Ca0.9Sr0.9Cu2Oy superconductor are reported. The structure is orthorhombic with a=5.63 Å, b=5.4 Å, and c=38.2 Å. The c parameter is different from those reported by other workers and suggests that two extra perovskite units ap, where ap=3.82 Å, have been introduced leading to c=10ap. EDX microanalysis shows that the Cu content of this phase is higher than that reported by other workers. It is suggested that the phase with c=38.2 Å may be the higher temperature (115 K) superconductor.
High T
c screen-printed YBa2Cu3O7−x films: Effect of the substrate material
Authors: Bansal Narottam P. , Simons Rainee N. , Farrell D. E.
Published: July 2002

Thick films of YBa2Cu3O7−x have been deposited on highly polished alumina, magnesia spinel, nickel aluminum titanate (Ni-Al-Ti), and barium tetratitanate (Ba-Ti) substrates by the screen printing technique. They were baked at 1000 °C for 15 min, oxygen annealed at a lower temperature, and characterized by electrical resistivity measurements, x-ray diffraction, and optical and scanning electron microscopy. Properties of the films were found to be highly sensitive to the choice of the substrate material. The film on Ba-Ti turned green after firing, due to a reaction with the substrate and were insulating. A film on Ni-Al-Ti had a Tc  (onset) ∼95 K and lost 90% of its resistance by ∼75 K. However, even at 4 K it was not fully superconducting, possibly due to a reaction between the film and the substrate and interdiffusion of the reaction products. The film on alumina had Tc  (onset) ∼96 K, Tc  (zero) ∼66 K, and ΔTc  (10–90%) ∼10 K. Our best film was obtained on spinel and had Tc  (onset) ∼94 K, zero resistance at 81 K, and a transition width (10–90%) of ∼7 K.
Tunable microwigglers for free-electron lasers
Authors: Chen S. C. , Bekefi G. , DiCecca S. , Temkin R.
Published: July 2002

We present the design, construction, and test results of a novel microwiggler structure with a periodicity of 2.4 mm for free-electron laser applications. The experimentally demonstrated tunability of field amplitude provides versatile means for field tapering, optical klystron configurations, improving field uniformity, and electron beam matching at the wiggler entrance.
Calculated phonon spectra of Si/Ge (001) superlattices: Features for interface characterization
Authors: Molinari E. , Fasolino A.
Published: July 2002

We present a model calculation or phonon spectra of Si/Ge superlattices along the (001) growth direction. The most relevant result for structural characterization is that interface modes involving the SiGe bonds at the interface are predicted only in the transverse and not in the longitudinal polarization. The detection of such modes between the Si-like and Ge-like optical modes in backscattering Raman spectra from the (001) surface must then be ascribed to interface disorder or alloying.
Determination of free carrier concentration profiles and the valence-band discontinuity energy of Hg0.7Cd0.3Te/Cd(4% Zn)Te heterojunctions using organic semiconductor layers
Authors: Chang S. J. , Leu L. Y. , Forrest S. R. , Jones C. E.
Published: July 2002

Capacitance-voltage data are utilized to obtain the free-carrier concentration in n- and p-type Hg1−yCdyTe layers, and to measure the valence-band discontinuity energy of a p-type Hg0.7Cd0.3Te/Cd(4% Zn)Te isotype heterojunction. To facilitate measurement, rectifying contact was made to the Hg1−yCdyTe layers using one of two organic materials—metal-free phthalocyanine and copper phthalocyanine. Contrary to previous results with this heterojunction system, we find that holes are accumulated near the Cd(4% Zn)Te side (rather than Hg1−yCdyTe side). We obtain a valence band discontinuity energy (ΔEv ) equal to (110±20) meV, and a fixed interface charge density of σ=−(5.9±0.3)×1010 cm−2.
14 GHz single-mode picosecond optical pulse train generation in Zn-doped distributed-feedback lasers
Authors: Kamite K. , Sudo H. , Sugano M. , Soda H. , Kusunoki T. , Ishikawa H.
Published: July 2002

To generate ultrashort pulse train at a high repetition rate, Zn was doped to the active region of distributed-feedback lasers. Increase in the differential gain and reduction of the carrier lifetime have been confirmed. The 3 dB bandwidth was increased to 16 GHz. The 14 ps single longitudinal mode optical pulse train at a repetition rate of 14 GHz was generated by gain-switched operation.
Selected area growth of GaAs by laser-induced pyrolysis of adsorbed triethylgallium
Authors: Donnelly V. M. , McCaulley J. A.
Published: July 2002

We report selected area growth of GaAs by XeF excimer laser induced pyrolysis of triethylgallium (TEGa) adsorbed on GaAs(100). TEGa dissociatively chemisorbs at 400 °C to form a stable layer which decomposes further under laser irradiation to liberate hydrocarbon products. The Ga left behind on the surface reacts with As2 and As4 (formed by pyrolysis of trimethylarsine or triethylarsine in a side tube) to grow GaAs in irradiated areas. Patterned films with feature sizes of ∼70 μm (limited by the projection system) were grown by this method. Interference between the incident beam and light scattered along the surface causes a substructure of parallel lines, with a spacing about equal to the laser wavelength (0.35 μm), to form on the features. This indicates that the ultimate spatial resolution is comparable to that predicted by thermal diffusion calculations (∼0.3 μm).
Gain-loss model for the dependence of the stimulated-emission transition in AlGaAs-GaAs quantum well heterostructures on photoexcitation geometry
Authors: Vojak B. A. , Holonyak N.
Published: July 2002

The gain-loss laser oscillation condition is applied to photoexcitation geometries in which phonon-assisted laser operation is observed in AlGaAs-GaAs quantum well heterostructures (QWHs). The model is found to agree with a variety of experimental conditions in which cavity size, photoexcitation spot size, and mirror reflectivity are varied. Also, it serves to indicate further how others might have failed to observe phonon-assisted laser operation in QWHs and how photoexcitation geometries can be varied to verify these results.
Smoothing of multilayer x-ray mirrors by ion polishing
Authors: Spiller Eberhard
Published: July 2002

Ion bombardment at grazing angles of incidence is used to smoothen the boundaries within multilayer x-ray mirrors. Increases in the reflectivity by a factor of 2 for soft x rays have been obtained for RhRu-C mirrors with periods of 60 Å.
Real-space transfer from quantum wells by polar optical phonon scattering
Authors: Lent Craig S. , Liang Lie , Porod Wolfgang
Published: July 2002

We calculate the rate at which electrons bound in a semiconductor quantum well are scattered out of the well by absorption or emission of polar optical phonons. This escape rate is important in real-space transfer devices and as a loss mechanism in high electron mobility transistors. Both quantum confinement effects and the two-dimensional (2D) to three-dimensional (3D) nature of the scattering are included. For all but very shallow wells, the real-space transfer rate is much smaller than either the bulk (3D) scattering rate or the confined (2D) scattering rate. Quantum resonances in the final state result in oscillations in the scattering rate as a function of electron energy.
Minority-hole diffusion length in heavily doped silicon
Authors: Wang Chih Hsin , Misiakos Konstantinos , Neugroschel Arnost
Published: July 2002

The minority-hole diffusion length in heavily doped n-type silicon wafers was measured in the doping range 1018–1020 cm−3. The experimental method is based on the lateral collection of photogenerated carriers by a semi-infinite junction. Closed form expressions available for this particular two-dimensional geometry greatly simplify the analysis of the experimental results. The results are consistent with an Auger-limited minority-carrier lifetime and a diffusion coefficient that is doping insensitive in the 1018–1020 cm−3 range.
Efficient light emission by impact ionization in single-barrier tunneling devices
Authors: Snow E. S. , Kirchoefer S. W. , Campbell P. M. , Glembocki O. J.
Published: July 2002

Efficient band-gap electroluminescence has been observed in n+-n−-n+ single-barrier tunneling devices. The electroluminescence arises from holes created by the impact ionization of electrons in large electric fields. From the voltage dependence of the electroluminescence the electric field dependence of the impact ionization rate is determined. Comparisons to theory are made.
Test of a two-dimensionally focusing quasi-optical antenna using a gyrotron
Authors: Idehara T. , Tatsukawa T. , Brand G. F. , Fekete P. W. , Moore K. J.
Published: July 2002

A quasi-optical antenna having one elliptical reflector and one parabolic reflector has been built for millimeter wave scattering measurements on the TORTUS tokamak plasma at the University of Sydney. This letter reports the first demonstration of the properties of such an antenna using a gyrotron millimeter wave source. Its advantages are (1) good two-dimensional focusing (along the major radius and the toroidal directions) and (2) easy movement of the focus across the diameter of the plasma by changing the orientation of the parabolic reflector.
Magnetic flux motion and its influence on transport properties of the high T
c oxide superconductors
Authors: Sun J. Z. , Char K. , Hahn M. R. , Geballe T. H. , Kapitulnik A.
Published: July 2002

High Tc superconductors exhibit significant flux motion due to a thermally activated creep process. The motion of the fluxoids dissipates energy. This dissipation causes a broadening of the resistive transition below Tc in a magnetic field as well as a logarithmic decay of the diamagnetic shielding moment in time. From the detailed structure of the broadened transition, empirical parameters are derived. The pinning strength is highly anisotropic, reflecting the anisotropy of the coherence length. Implications of an extraordinarily low activation energy are also addressed.
Propagation of terahertz bandwidth electrical pulses on YBa2Cu3O7−δ transmission lines on lanthanum aluminate
Authors: Nuss Martin C. , Mankiewich P. M. , Howard R. E. , Straughn B. L. , Harvey T. E. , Brandle C. D. , Berkstresser G. W. , Goossen K. W. , Smith P. R.
Published: July 2002

We study the propagation of terahertz bandwidth electrical pulses on high critical current density c-axis oriented YBa2Cu3O7−δ (YBCO) coplanar transmission lines deposited epitaxially on the low dielectric loss substrate lanthanum aluminate (LaAlO3). The losses on the YBCO transmission line are lower than on an equivalent gold line on the same substrate at temperatures below 50 K. At higher temperatures, absorption and dispersion of the ultrashort electrical pulses are observed in reasonable agreement with Mattis–Bardeen theory.
Complete single lateral 180° phase mode operation for AlGaAs phased array lasers
Authors: Sagawa M. , Kajimura T.
Published: July 2002

Single lateral 180° phase mode operation is realized at a light output of up to 90 mW under pulsed operation using uncoated AlGaAs phased array lasers. Phased array lasers consist of six elements. Each element has a self-aligned structure, with an interface layer of low AlAs mole fraction, and is fabricated by a two-step metalorganic chemical vapor deposition method, together with dry etching. Spectrally resolved, near-field measurements show that the phased array laser oscillates in a completely single lateral mode under pulsed operation. Measurements also show that a slight broadening of the far-field lobes under continuous wave operation is caused by generation of multiple lateral modes.
Shubnikov–de Haas effect in thin epitaxial films of gray tin
Authors: Tu L. W. , Wong G. K. , Song S. N. , Zhao Z. , Ketterson J. B.
Published: July 2002

The transverse magnetoresistance and Hall effect have been studied for n-type gray tin epilayers grown on (001)CdTe substrates by the molecular beam epitaxy technique. Shubnikov–de Haas oscillations were observed in samples having Hall mobilities ≥104 cm2 /V s at low temperatures. Measurements were carried out using both the dc method and field modulation techniques in the temperature range from 1.2 to 10 K and in magnetic fields up to 10 T. Beat patterns were observed in the Shubnikov–de Haas spectra which we ascribe either to inhomogeneous doping, arising from the diffusion of Cd and Te from the substrate, or to quantization of the motion in the direction parallel to the film normal. The Shubnikov–de Haas carrier concentration of a 1210 Å film was determined to be nSdH =2.3×1017 cm−3, in good agreement with the Hall density.
Full-wafer mapping of total and ionized EL2 concentration in semi-insulating GaAs using infrared absorption
Authors: Brierley Steven K. , Lehr Deborah S.
Published: July 2002

By combining infrared absorption data taken at two different wavelengths in the spectral region in which the native deep donor EL2 absorbs in GaAs, it is possible to determine the distribution of the total EL2 concentration and its filled fraction across a semi-insulating GaAs substrate. The distributions of net shallow acceptor concentration and free-electron concentration can then be deduced. Full-wafer maps of these quantities for a semi-insulating GaAs wafer are displayed along with Hall effect measurements which confirm the patterns observed optically.
Criterion for blocking threading dislocations by strained buffer layers in GaAs grown on Si substrates
Authors: El-Masry N. A. , Tarn J. C. L. , Hussien S.
Published: July 2002

An energy model has been used to calculate the minimum critical thickness in strained-layer superlattices that is required to block threading dislocations. The model calculates the total change in the system energy that results from the presence of a bent dislocation segment at the strained interface. The calculations show that a threading dislocation has to overcome an energy barrier before gliding along the strained-layer interface becomes favorable. The model predicts that the process of blocking threading dislocations by strained-layer structures can be thermally activated.
Implant and annealed ohmic contact to a thin quantum well
Authors: Yang C. H. , Plumton D. L. , Lodenkamper R. , Shih H. D.
Published: July 2002

We demonstrate for the first time that ion implantation and implant activation annealing, combined with a heavily doped InGaAs surface layer, can be used to make nonalloying shallow ohmic contact to an n-type InGaAs (or GaAs) quantum well. Quantum Hall effect and Shubnikov–de Haas oscillations are clearly observed, which indicates that electrons in the quantum well remain two dimensional despite the post-implantation high-temperature annealing. This technique can be applied to devices that would need to make shallow ohmic contact to a thin (∼100 Å or less) quantum well, where existing selective etching approaches fail to work.
Deposition and annealing of ion beam sputtered Y-Ba-Cu-O superconducting films
Authors: Bernstein S. D. , Tustison R. W.
Published: July 2002

Highly oriented, near-stoichiometric films of YBa2Cu3O7−δ have been deposited onto (100) MgO, (100) yttria-stabilized zirconia, and (110) SrTiO3 by ion beam sputtering from a single, off-stoichiometric target. Their crystal structure and resistance behavior were found to depend on the crystallization temperature of a two-step post-deposition anneal, which was varied from 750 to 1000 °C. The highest zero-resistance temperature (73 K) and degree of preferred orientation was observed for a film which was deposited on (100) MgO and annealed for a short time at 950 °C.
HgCdTe 128×128 infrared focal plane arrays on alternative substrates of CdZnTe/GaAs/Si
Authors: Johnson S. M. , Kalisher M. H. , Ahlgren W. L. , James J. B. , Cockrum C. A.
Published: July 2002

High quality p-on-n heterojunction infrared detectors have been fabricated using controllably doped HgCdTe grown by liquid phase epitaxy on CdZnTe/GaAs/Si alternative substrates grown by metalorganic chemical vapor deposition and used to demonstrate the first 128×128 focal plane array fabricated on these materials. Detectors with a cutoff wavelength of 6.0 μm and a resistance-area product R0 Aj average of 6.0×104 Ω cm2 at 80 K for 16 189 detectors in the array were achieved, and for operating temperatures above approximately 120 K were comparable in performance to detectors co-fabricated on standard lattice-matched bulk CdZnTe substrates. Below 120 K, detector performance was limited by excess generation-recombination current, probably caused by a higher threading dislocation density compared with that for the bulk substrates.
Evidence of segregation in (100) strained Si1−xGex alloys grown at low temperature by molecular beam epitaxy
Authors: Croke E. T. , McGill T. C. , Hauenstein R. J. , Miles R. H.
Published: July 2002

High quality, coherently strained Si1−xGex alloy layers are studied using high-resolution x-ray diffraction (HRXRD) and ex situ transmission electron diffraction. Several samples were grown at extremely low temperatures (310–330 °C) by molecular beam epitaxy. Sample thicknesses and alloy concentrations were chosen to span a range beginning just below to significantly above critical thicknesses previously reported for this system. HRXRD observations demonstrate a high degree of coherency in the as-grown structures since measurements of the lattice constant parallel to the sample surface (a∥) consistently yield the value for the (100)Si substrate. HRXRD from (004) planes used to measure a⊥ typically yield a spectrum with several peaks for growths in excess of the critical thickness and single peaks for those below the critical thickness. The high degree of coherency observed in these samples suggests that chemical segregation is responsible for the observed x-ray peaks.
Reduced Staebler–Wronski effect in reactively sputtered hydrogenated amorphous silicon thin films
Authors: Pinarbasi Mustafa , Abelson John R. , Kushner Mark J.
Published: July 2002

The kinetics of light-induced defect generation or the Staebler–Wronski effect (SWE) have been measured on device quality hydrogenated amorphous silicon (a-Si:H) films having hydrogen contents (CH) of ∼10–28 at. %. The films were deposited with direct current (dc) magnetron reactive sputtering. The low CH films have a density of defect states (DOS)∼7 to 10×1015 cm−3 which is three to five times higher than the high CH films. Under light exposure, the DOS for low CH films increases slower than that of the high CH or glow discharge produced films; in fact it is smaller after a few hours of light exposure. These measurements show that low CH dc magnetron reactively sputtered a-Si:H appears to be more stable material for sensitive applications such as solar cells.