bluuebunny/crossref_metadata_2025 huggingface dataset:
Human pancreatic phospholipase A2 stimulates the growth of human pancreatic cancer cell line
Authors: Hanada Keiji , Kinoshita Eiji , Itoh Masaki , Hirata Manabu , Kajiyama Goro , Sugiyama Masanori
Published: July 2002

Phospholipase A2 (PLA2) from human pancreas, designated hPLA2‐I, functions as a digestive enzyme. Interestingly, the present study demonstrated that the mature form of hPLA2‐I stimulated the growth of a human pancreatic cancer cell line MIAPaCa‐2, whereas the pro‐form was ineffective. PLA2s from Laticauda semifasciata fraction I, Crotalus adamanteus venom, Streptomyces violaceoruber and bee venom, showed no proliferative effect to the growth of MIAPaCa‐2. The Scatchard plot analysis revealed that the MIAPaCa‐2 cell had a specific binding site for the mature hPLA2‐I. The equilibrium binding constant (K
d) and the maximum binding capacity (B
max) were 2.6 nM and 0.4 fmol/106 cells, respectively. These results suggest that the mature hPLA2‐I, but not the pro‐form, may function as a growth factor of pancreas carcinoma via the specific binding site.
Folding of a synthetic parallel β‐roll protein
Authors: Lilie Hauke , Haehnel Wolfgang , Rudolph Rainer , Baumann Ulrich
Published: July 2002

Recently, the design of β‐sheet proteins and concomitant folding studies have attracted increasing attention. A unique natural all‐β domain occurs in a family of cytolytic bacterial toxins, the so‐called RTX toxins. This domain consists of a variable number (about 6–45) of tandem repeats of a glycine‐rich nine‐residue motif with the consensus sequence GGXGXDX(L/I/F)X. The analysis of the three‐dimensional structure of alkaline protease from Pseudomonas aeruginosa which possesses six of these repeats revealed that they fold into a novel 'parallel β‐roll’ where calcium is bound within the turns connecting the β‐strands. A 75‐mer peptide of the sequence NH2‐WLS‐[GGSGNDNLS]8‐COOH was chemically synthesised. Circular dichroism spectroscopy showed that this polypeptide folds in the presence of Ca2+ and polyethylene glycol into a β‐structure which is presumably identical with the parallel β‐roll. This synthetic β‐roll behaves similarly to the isolated β‐roll domains from Escherichia coli haemolysin or Bordetella pertussis cyclolysin in terms of calcium binding and polymerisation behaviour.
Enhancement of radiation response in human cervical cancer cells in vitro and in vivo by arsenic trioxide (As2O3)
Authors: Chun Yong-Jin , Park In-Chul , Park Myung-Jin , Woo Sang-Hyeok , Hong Seok-Il , Chung Hee Yong , Kim Tae-Hwan , Lee Yun-Sil , Rhee Chang-Hun , Lee Su-Jae
Published: July 2002

Arsenic trioxide (As2O3) inhibits cell growth and induces apoptosis in certain types of cancer cells including acute promyelocytic leukemia, prostate and ovarian carcinomas, but its effect on response of tumor cells to ionizing radiation has never been explored before. Here we demonstrate that As2O3 can sensitize human cervical cancer cells to ionizing radiation both in vitro and in vivo. As2O3 in combination with ionizing radiation have a synergistic effect in decreasing clonogenic survival and in the regression of established human cervical tumor xenografts. Pretreatment of the cells with As2O3 also synergistically enhanced radiation‐induced apoptosis. Apoptosis of the cells by combined treatment of As2O3 and radiation was associated with reactive oxygen species generation and loss of mitochondrial membrane potential, resulting in the activation of caspase‐9 and caspase‐3. The combined treatment also resulted in an increased G2/M cell cycle distribution at the concentration of As2O3 which did not alter cell cycle when applied alone. These results indicate that As2O3 can synergistically enhance radiosensitivity of human cervix carcinoma cells in vitro and in vivo, suggesting a potential clinical applicability of combination treatment of As2O3 and ionizing radiation in cancer therapies.
CROP/Luc7A, a novel serine/arginine‐rich nuclear protein, isolated from cisplatin‐resistant cell line1
Authors: Nishii Yoichi , Morishima Masaki , Kakehi Yoshiyuki , Umehara Kouji , Kioka Noriyuki , Terano Yoshitake , Amachi Teruo , Ueda Kazumitsu
Published: July 2002

A novel putative SR protein, designated cisplatin resistance‐associated overexpressed protein (CROP), has been cloned from cisplatin‐resistant cell lines by differential display. The N‐half of the deduced amino acid sequence of 432 amino acids of CROP contains cysteine/histidine motifs and leucine zipper‐like repeats. The C‐half consists mostly of charged and polar amino acids: arginine (58 residues or 25%), glutamate (36 residues or 16%), serine (35 residues or 15%), lysine (30 residues, 13%), and aspartate (20 residues or 9%). The C‐half is extremely hydrophilic and comprises domains rich in lysine and glutamate residues, rich in alternating arginine and glutamate residues, and rich in arginine and serine residues. The arginine/serine‐rich domain is dominated by a series of 8 amino acid imperfect repetitive motif (consensus sequence, Ser‐Arg‐Ser‐Arg‐Asp/Glu‐Arg‐Arg‐Arg), which has been found in RNA splicing factors. The RNase protection assay and Western blotting analysis indicate that the expression of CROP is about 2–3‐fold higher in mRNA and protein levels in cisplatin‐resistant ACHN/CDDP cells than in host ACHN cells. CROP is the human homologue of yeast Luc7p, which is supposed to be involved in 5′‐splice site recognition and is essential for vegetative growth.
Comparison of the Emulsion Characteristics of Rhodococcus erythropolis and Ecsherichia coli SOXC‐5 Cells Expressing Biodesulfurization Genes
Authors: Borole Abhijeet P. , Kaufman Eric N. , Grossman Matthew J. , Minak‐Bernero Vera , Bare Richard , Lee M. Kathryn
Published: July 2002

Biodesulfurization of fuel oils is a two‐phase (oil/water) process which may offer an interesting alternative to conventional hydrodesulfurization due to the mild operating conditions and reaction specificity afforded by the biocatalyst. For biodesulfurization to realize commercial success, a variety of process considerations must be addressed including reaction rate, emulsion formation and breakage, biocatalyst recovery, and both gas and liquid mass transport. This study evaluates emulsion formation and breakage using two biocatalysts with differing hydrophobic characteristics. A Gram‐positive ( Rhodococcus erythropolis) biocatalyst, expressing the complete 4S desulfurization pathway, and a Gram‐negative biocatalyst ( Escherichia coli), expressing only the gene for conversion of dibenzothiophene (DBT) to DBT sulfone, are compared relative to their ability to convert DBT and the ease of phase separation as well as biocatalyst recovery following desulfurization.
Production of Fructose and Ethanol from Sugar Beet Molasses Using Saccharomyces cerevisiae ATCC 36858
Authors: Atiyeh Hasan , Duvnjak Zdravko
Published: July 2002

The production of enriched fructose syrups and ethanol from beet molasses using Saccharomyces cerevisiae ATCC 36858 was studied. In batch experiments with a total sugar concentration between 94.9 and 312.4 g/L, the fructose yield was above 93% of the theoretical value. The ethanol yield and volumetric productivity in the beet molasses media with sugar concentration below 276.2 g/L were in the range of 59–76% of theoretical value and between 0.48 and 2.97 g of ethanol/(L·h), respectively. The fructose fraction in the carbohydrates content of the produced syrups was more than 95% when the total initial sugar concentration in the medium was below 242.0 g/L. Some oligosaccharides and glycerol were also produced in all tested media. Raffinose and the produced oligosaccharides were completely consumed by the end of the fermentation process when the total initial sugar concentration was below 190.1 g/L. The glycerol concentration was below 16.1 g/L. The results could be useful for a potential industrial production of ethanol and high‐fructose syrup from sugar beet molasses.
Selectively 2H‐labeledGlu/Asp: application to pKa measurements in Aβ amyloid peptides
Authors: Zhang S. , Lee J.P.
Published: July 2002

Abstract: Human Aβ peptides have been linked to Alzheimer’s disease, and it is hypothesized that formation of amyloid as well as neurotoxicity are important events in the etiology of the disease. Previous studies have shown that the soluble precursor to Alzheimer’s amyloid undergoes a pH‐dependent folding transition as the self‐assembly activity appears, and based upon inter‐residue proximities, it was suspected that stabilization of the soluble form might rely upon formation of an intramolecular salt‐bridge. However, pKa studies on a model 17‐residue Aβ fragment supported an electrostatic model where a solvation imperative for charged side‐chain atoms drives the folding process. To explore this model in an active 26‐residue fragment as well as the full‐length 40‐residue Αβ peptide, pKa measurements were performed via 1H and 2H NMR. To overcome issues related to sensitivity and spin system degeneracy, specifically deuterated allyl protected‐Fmoc amino acids were synthesized for incorporation into a series of peptides, and a high sensitivity 2H observe NMR probe was constructed.
Evidence for the nitration of γ-tocopherol in vivo: 5-nitro-γ-tocopherol is elevated in the plasma of subjects with coronary heart disease
Authors: MORTON Lincoln W. , WARD Natalie C. , CROFT Kevin D. , PUDDEY Ian B.
Published: July 2002

This study investigated the hypothesis that nitration of γ-tocopherol may be an important mechanism for the detoxification of reactive nitrogen oxide species in vivo. Using liquid chromatography—tandem MS we have shown that γ-tocopherol can be nitrated in vivo to form 5-nitro-γ-tocopherol and that concentrations of this compound are elevated in the plasma of subjects with coronary heart disease. In addition, we demonstrate in carotid-artery atherosclerotic plaque that nitration of γ-tocopherol is also evident at levels similar to that seen in the plasma of subjects with coronary heart disease.
Truncation of Arabidopsis thaliana and Selaginella lepidophylla trehalose-6-phosphate synthase unlocks high catalytic activity and supports high trehalose levels on expression in yeast
Authors: Van DIJCK Patrick , MASCORRO-GALLARDO José O. , De BUS Martien , ROYACKERS Katrien , ITURRIAGA Gabriel , THEVELEIN Johan M.
Published: July 2002

Plants, such as Arabidopsis thaliana and Selaginella lepidophylla, contain genes homologous with the trehalose-6-phosphate synthase (TPS) genes of bacteria and fungi. Most plants do not accumulate trehalose with the desert resurrection plant S. lepidophylla, being a notable exception. Overexpression of the plant genes in a Saccharomyces cerevisiae tps1 mutant results in very low TPS-catalytic activity and trehalose accumulation. We show that truncation of the plant-specific N-terminal extension in the A. thalianaAtTPS1 and S. lepidophyllaSlTPS1 homologues results in 10–40-fold higher TPS activity and 20–40-fold higher trehalose accumulation on expression in yeast. These results show that the plant TPS enzymes possess a high-potential catalytic activity. The growth defect of the tps1 strain on glucose was restored, however, the proper homoeostasis of glycolytic flux was not restored, indicating that the plant enzymes were unable to substitute for the yeast enzyme in the regulation of hexokinase activity. Further analysis of the N-terminus led to the identification of two conserved residues, which after mutagenesis result in strongly enhanced trehalose accumulation upon expression in yeast. The plant-specific N-terminal region may act as an inhibitory domain allowing modulation of TPS activity.
Two isoforms of Saccharomyces cerevisiae glutaredoxin 2 are expressed in vivo and localize to different subcellular compartments
Authors: PEDRAJAS José R. , PORRAS Pablo , MARTÍNEZ-GALISTEO Emilia , PADILLA C. Alicia , MIRANDA-VIZUETE Antonio , BÁRCENA J. Antonio
Published: July 2002

Glutaredoxin (Grx)2 from Saccharomyces cerevisiae is a member of the two-cysteine (dithiol) subfamily of Grxs involved in the defence against oxidative stress in yeast. Recombinant yeast Grx2p, expressed in Escherichia coli, behaves as a ‘classical’ Grx that efficiently catalyses the reduction of hydroxyethyl disulphide by GSH. Grx2p also catalyses the reduction of GSSG by dihydrolipoamide with even higher efficiency. Western blot analysis of S. cerevisiae crude extracts identifies two isoforms of Grx2p of 15.9 and 11.9kDa respectively. The levels of these two isoforms reach a peak during the exponential phase of growth in normal yeast extract/peptone/dextrose ('YPD') medium, with the long form predominating over the short one. From immunochemical analysis of subcellular fractions, it is shown that both isoforms are present in mitochondria, but only the short one is detected in the cytosolic fraction. On the other hand, only the long form is prominent in microsomes. Mitochondrial isoforms should represent the processed and unprocessed products of an open reading frame (YDR513W), with a putative start codon 99bp upstream of the GRX2 start codon described thus far. These results indicate that GRX2 contains two in-frame start codons, and that translation from the first AUG results in a product that is targeted to mitochondria. The cytosolic form would result either by initiation from the second AUG, or by differential processing of one single translation product.
Long‐term outcome of patients surviving for more than ten years following treatment for acute leukaemia
Authors: Micallef Ivana N. M. , Rohatiner Ama Z. S. , Carter Maxine , Boyle Margaret , Slater Sarah , Amess John A. L. , Lister T. Andrew
Published: July 2002

Between 1972 and 1988, 832 consecutive patients were treated for acute leukaemia at St. Bartholomew's Hospital; a retrospective analysis has been conducted to determine the clinical course and outcome for 101 who have survived ≥ 10 years following treatment. At a median follow‐up of 16 years (range 10–28 years), 86 patients (86 out of 834 total, 11%) were still alive. Long‐term follow‐up of patients who have survived ≥ 10 years following treatment for acute leukaemia revealed that most patients were in normal health, although a significant number of complications had occurred.
An Alternative Perspective to the Immune Response in Autoimmune Exocrinopathy: Induction of Functional Quiescence Rather Than Destructive Autoaggression
Authors: HUMPHREYS‐BEHER M. G. , BRAYER J. , YAMACHIKA S. , PECK A. B. , JONSSON R.
Published: July 2002

Sjögren's syndrome is characterized by dryness of the eyes and the mouth due to mononuclear cell infiltration of the lacrimal and salivary glands. The aetiology is unknown but autoimmunity is considered to play a significant role in the pathogenesis. Recent studies have focused on the fact that tear and salivary flow involves an entire functional system that includes the mucosal surfaces with adnexes (the site of inflammation), efferent nerve signals sent to the midbrain (lacrimal and salivary response region), and afferent neural signals from the brain to the acinar/ductal epithelial structures in the gland. Mononuclear cell infiltration in exocrine glands can lead to glandular destruction, suggested to be mediated through apoptosis. However, the functional impairment of exocrine glands could be regulated by cytokines and/or antibodies against the muscarinic M3 receptor by inhibiting the neural stimulation of the residual glands. This review discusses the possibility that the pathogenesis of Sjögren's syndrome comprises aberrant immune‐mediated neuro‐hormonal events.
Transcription activation mediated by the bZIP factor SPA on the endosperm box is modulated by ESBF‐1 in vitro
Authors: Conlan R. Steven , Hammond‐Kosack Michael , Bevan Michael
Published: July 2002

A modified in vitro transcription system has been used to study the function of the cloned bZIP transcription factor SPA and the binding activity ESBF I in activating transcription from the bifactorial endosperm box region of the wheat prolamin LMWG‐1D1 gene. Recombinant SPA expressed in Escherichia coli activated transcription from the endosperm box motif, and this was dependent upon the binding of the nuclear protein ESBF I. ESBF I did not activate transcription independently, but potentiated SPA‐mediated transcriptional activation. ESBF I is likely to be the equivalent of, or contain the recently characterised DOF class of, Zn‐finger protein called WPBF. These data provide new information about the interplay of members of the bZIP and DOF transcription factor families in regulating expression from bifactorial sites found in a variety of plant promoters.
A case‐control study of transmission routes for GB virus C/hepatitis G virus in Swedish blood donors lacking markers for hepatitis C virus infection
Authors: Björkman P. , Nauclér A. , Winqvist N. , Mushahwar I. , Widell A.
Published: July 2002

Background and Objectives

The transmission routes for GB virus‐C (GBV‐C)/hepatitis G virus (HGV) in blood donors unexposed to hepatitis C virus (HCV) are unknown. We performed a case‐control study of risk factors for GBV‐C/HGV exposure in blood donors.

Materials and Methods

After testing stored sera from 458 HCV‐negative blood donors for GBV‐C/HGV RNA and GBV‐C/HGV E2 antibodies, 66 donors with GBV‐C/HGV markers and 125 age‐ and gender‐matched controls were interviewed regarding risk factors for viral transmission.

Results

Exposure to GBV‐C/HGV was strongly associated with previous treatment for a sexually transmitted disease (odds ratio [OR] 4·6; 95% confidence interval [CI] 2·2–9·8), with multiple sexual partners (OR 2·9; 95% CI 1·4–5·7) and with a past history of endoscopy (OR 7·0; 95% CI 3·0–16·4).

Conclusions

In blood donors with GBV‐C/HGV markers, sexual contacts and medical procedures appear to be the main transmission routes.
Ethology of Hygienic Behaviour in the Honey Bee Apis mellifera L. (Hymenoptera: Apidae): Behavioural repertoire of Hygienic bees
Authors: Arathi H.S. , Burns I , Spivak M.
Published: July 2002

Hygienic behaviour performed by middle‐aged worker bees is an important intranidal task in colonies of the honey bee Apis mellifera (L.). It comprises detecting diseased brood in the larval and pupal stages and removing all such infected brood, thereby decreasing the incidence of infection. Hygienic behaviour consists of two task‐components: uncapping cells and removing the cell contents. The aim of this study was to observe bees performing hygienic behaviour to determine their age at performance of the behaviour and to describe their behavioural repertoire. The bees performing hygienic behaviour were middle‐aged bees, younger than foragers. In the colonies where the behaviours of individual bees were observed, all bees performing the hygienic behaviour were seen to exhibit both the components, though at different frequencies. One behavioural class performed the task of uncapping cells at higher frequencies than the task of removing cell contents, while another class performed both tasks to the same extent. While these two classes had higher frequencies of the tasks comprising the hygienic behaviour but lower frequencies of other common behaviours in their repertoire, a third class of bees included those that performed all behaviours in their repertoire at similar frequencies. There was no difference in the ages of the bees in these three behavioural classes. These results suggest that there is no evidence of task partitioning among bees performing the hygienic behaviour. The segregation observed could, however, be based on their response thresholds to the stimulus and/or on their ability to discriminate the various cues emanating from the dead brood.
Neuroendocrine cells of the verumontanum: a comparative immunohistochemical study
Authors: Guy  , BÉgin  , AL‐Othman  , Chevalier  , Aprikian
Published: July 2002

Objective

 To define the distribution of neuroendocrine (NE) cells in the different compartments of the verumontanum (utricle, ejaculatory ducts, main prostatic ducts) in relation to other areas of the prostate.

Materials and methods

 A retrospective study was conducted of 30 radical prostatectomy specimens processed in toto as whole‐mount sections. Among these cases, 15 patients had received a preoperative short course of total androgen blockade. The distribution and number of NE cells in the prostatic utricle and in normal areas of the prostate were analysed using chromogranin A (CgA) and serotonin immunohistochemistry; prostate‐specific antigen (PSA) immunostaining was performed systematically on a consecutive section. Six cases of endometrioid carcinomas were also investigated using these methods. The vascularization of the verumontanum was assessed by factor VIII immunohistochemistry and examined in relation to vascular endothelial growth factor (VEGF) immunohistochemistry.

Results

 There were significantly more NE cells in the prostatic utricle than in the main prostatic ducts of the verumontanum and the peripheral prostatic acini. In the ejaculatory ducts, there were NE cells only in the extreme distal portion. Cells immunoreactive for PSA were present at the level of the utricle and the extreme distal portion of the ejaculatory ducts. The distribution, number and shape of NE cells were unaltered by hormonal treatment. NE cells of the verumontanum were positive for VEGF expression. Factor VIII detected more vessels around the utricle and ejaculatory ducts. NE cells (positive for CgA and serotonin) were observed in three cases of endometrioid carcinoma.

Conclusion

 The high concentration of NE cells found in the prostatic utricle suggests a possible role for these cells in human fertility. Moreover, neuroendocrine differentiation in endometrioid (large duct) carcinoma, documented for the first time, supports the concept that this cancer type is a variant of a conventional adenocarcinoma.
Effects of exercise on aspects of visual function
Authors: Woods Russell L. , Thomson W. David
Published: July 2002

Strenuous exercise has been reported to affect various aspects of visual and ocular function. In the first of two experiments, the effects of cycling, jogging and stair running on a range of visual functions were examined. None of these forms of exercise was found to have any significant effect on visual acuity, refractive error, dark focus, amplitude of accommodation or pupil size. Contrast sensitivity (CS), measured by an ascending method of limits (AML), was found to improve significantly after cycling and jogging but not after stair running. To investigate if the apparent improvement in CS was related to a change in ‘sensitivity’ or a change in decision criteria, CS was re‐measured before and after cycling using both the AML and a ‘criterion‐free’ method of constant stimuli (MOCS) procedure. Results obtained using the AML, confirmed the findings of the first experiment. However, results obtained using the MOCS procedure showed no significant change with exercise. This suggests that the improvement in CS found using the AML was due to a shift in subjects' decision criteria rather than a physiological change in ‘sensitivity’. It is argued that this change in decision criteria may be related to the positive mood changes which have been found to occur after exercise. This study demonstrates the importance of differentiating between changes in ‘sensitivity’ and changes in decision criteria especially where mood or motivation (and hence decision criteria) may be confounded with the independent variable. This is particularly important when evaluating the effects of exercise on visual function or evaluating the efficacy of vision training.
Identifying Conservation‐Priority Areas in the Tropics: a Land‐Use Change Modeling Approach
Authors: Menon Shaily , Pontius R. Gil , Rose Joseph , Khan M. L. , Bawa Kamaljit S.
Published: July 2002

Abstract: Most quantitative methods for identifying conservation‐priority areas require more detailed knowledge about the extent and distribution of biodiversity than is currently available. Accelerated and irreversible losses of biodiversity call for the development of alternative methods to identify priority sites for biodiversity inventory and protection. We focused on the state of Arunachal Pradesh, a biodiversity‐rich region in northeast India. We used a geographic information system and spatially explicit modeling to examine the correlation of land‐cover and land‐use patterns with biogeophysical characteristics and to project future patterns of land‐use change. In 1988, 70% of Arunachal Pradesh was covered by forest. We project that 50% of the state's 1988 forest will be lost by 2021, based on anticipated growth of the human population and resulting resource use. Of the total simulated deforestation, 76% occurs in areas that have no legal state protection. We developed a map of threats to biodiversity that divides areas that were forested in 1988 into four categories: (1) susceptible to future deforestation and currently unprotected; (2) susceptible to future deforestation but currently within the protected‐area network; (3) not susceptible to future deforestation and protected; and (4) neither susceptible to future deforestation nor currently protected. We make the following recommendations based on our analyses. Areas in category 1 should be a high priority for biodiversity inventory and conservation action. Areas in category 2 should have rigid enforcement of protection. Areas in category 3 are locations of relatively low priority for enforcement. Areas in category 4 that have a high conservation potential are politically the easiest to include in the protected‐area network and should be protected before they become targets of future land‐use change. Reserve forests—forests managed by the state forest department for a variety of purposes, including selective logging for timber harvesting—are predominantly located in areas susceptible to land‐use change and are prime candidates for upgrading of protection status.
Effects of Oral Estrogen and Progestin on the Lower Urinary Tract Among Female Nursing Home Residents
Authors: Ouslander Joseph G. , Greendale Gail A. , Uman Gwen , Lee Carol , Paul Wendy , Schnelle John
Published: July 2002

OBJECTIVE: To examine the effects of oral estrogen/progestin on incontinence and related lower urinary tract conditions among female nursing home (NH) residents.

DESIGN: Randomized placebo‐controlled trial.

SETTING: Five NHs.

PARTICIPANTS: Thirty‐two incontinent female residents of average age 88.

MEASUREMENTS: Subjects were randomized to receive either oral estrogen (0.625 mg) combined with progesterone (2.5 mg) or placebo, daily for 6 months. Measures of incontinence severity, the clinical appearance of the vagina, vaginal and urethral cytology, and urine and vaginal cultures were made at baseline, 3 months, and 6 months. In addition to active drug or placebo, all subjects received regular toileting assistance (prompted voiding) by trained research aides during 3‐day data‐collection periods to compensate for mobility and cognitive impairments.

RESULTS: At 3 and 6 months there were no significant differences between the groups in the severity of incontinence, the prevalence of bacteriuria, or the results of vaginal cultures. Several clinical findings associated with atrophic vaginitis improved more in the active than the placebo group and vaginal pH and vaginal and urethral cytology exhibited a partial estrogenic effect.

CONCLUSIONS: Our results must be interpreted with caution because of the size and the select nature of our subject sample. Up to 6 months of oral estrogen had only a partial estrogenic effect on vaginal and urethral epithelium and no clinical effects in this patient population. We believe that future studies of estrogen for urinary incontinence in frail NH residents should utilize a topical preparation and consider targeting urinary tract infection as an additional outcome measure.
Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation
Authors: See C. W. , Appel R. K. , Somekh M. G.
Published: July 2002

A scanning optical profilometer is described which can simultaneously and independently measure the differential phase/amplitude variation of light reflected off an object surface. This information may then be interpreted as topographical and reflectivity variation of the object surface. The system is based on a heterodyne interferometer and uses two beams to probe the surface. The theoretical sensitivity of the system is 3×10−3 mrad in phase and 3 in 105 in reflectivity variation, both measured in a 1 kHz bandwidth. Preliminary measurements of film thickness and reflectivity variation are presented. This system also has potential applications for imaging objects with minute structural variations.
Magnetization measurements of single levitated grains of Ba2YCu3O7
Authors: Grader G. S. , Hebard A. F. , Eick R. H.
Published: July 2002

An electrodynamic balance has been constructed in which the perturbative forces from applied magnetic fields are used to probe the superconducting properties of single levitated charged grains of high Tc superconductors with diameters ≲10 μm. The low-temperature magnetization of selected Ba2YCu3O7 grains has been observed to exhibit a flux exclusion near 80% of the theoretical maximum. Hysteresis, flux creep, and the lower critical field are identified.
Direct observation of glide dislocations in a KCl crystal by the light scattering method
Authors: Kataoka T. , Ohji H. , Kishida K. , Azuma K. , Yamada T.
Published: July 2002

The edge-like dislocations in a KCl single crystal produced by plastic deformation have been observed successfully by a 90° angle light scattering method using a scanning type microscope constructed with a high-power Ar-ion laser (2 W for a wavelength of 514 nm) and a conventional optical microscope. The image of glide dislocations was very sharp and uniform compared with that of grown-in dislocations. The orientation dependence of light scattering agreed with Moriya–Ogawa’s theory [Philos. Mag. A 41, 191 (1980)].
Anomalous inductive effect in selenium Schottky diodes
Authors: Champness C. H. , Clark W. R.
Published: July 2002

A region of anomalous negative capacitance has been observed with forward bias in Se-Tl Schottky evaporated layer structures. The effect, which is more prevalent in diodes with lower series resistance, is due to an inductive contribution to the impedance that is believed to arise from high-level injection of minority electrons into the bulk selenium.
Self-developing holographic recording in Li-implanted Te thin films
Authors: Beauvais J. , Lessard R. A. , Galarneau P. , Knystautas E. J.
Published: July 2002

Ablative holographic recording was performed on Li-implanted Te thin films using a Nd:YAG laser. Implantation doses ranging from 2.9×1013 to 2.3×1015 ions/cm2 within the thin films were seen to produce an increase of the writing threshold by 20% and a reduction of the diffraction efficiency of the recorded gratings at the highest doses. For doses as low as 1.2×1014 ions/cm2, a considerable increase in the stability of the recording media has been observed.
Noncontact energy level analysis of metallic impurities in silicon crystals
Authors: Kirino Y. , Buczkowski A. , Radzimski Z. J. , Rozgonyi G. A. , Shimura F.
Published: July 2002

Noncontact laser/microwave deep level transient spectroscopy (LM-DLTS) based on the measurement of microwave reflection power as a function of temperature has been developed and applied to Czochralski silicon crystals intentionally contaminated with selected metals during crystal growth. The energy levels related to these metallic impurities in p-type silicon have been obtained on bare silicon for the first time without any electrode contact or special sample preparation. The data agree in very satisfactory fashion with results obtained by conventional DLTS.
Etching of polymers by oxygen plasmas: Influence of viscoelastic properties
Authors: Joubert O. , Paniez P. , Pelletier J. , Pons M.
Published: July 2002

A study of novolac polymer etching in an oxygen microwave multipolar plasma with independent rf wafer biasing is reported. A step-like etch rate variation with temperature is observed for these polymers. Experiments conducted on chemically identical novolacs with different molecular weights allow this phenomenon to be correlated with their glass transition temperatures. Etch rate variations are caused by the thermal effect of ion bombardment, emphasizing the role of viscoelastic properties in polymer plasma etching.
Composition dependence of the second-harmonic phase-matching temperature in LiNbO3
Authors: Schmidt N. , Betzler K. , Grabmaier B. C.
Published: July 2002

Phase-matching temperatures for 90° phase matching of Nd:YAG laser light have been measured in LiNbO3 crystals with different Li/Nb ratios. Their melt and solid composition had been determined chemically with an accuracy of about 0.2%. Our results contrast to earlier work, no linear dependence of the phase-matching temperature versus the Li/Nb ratio was found. The measured dependence shows that the phase-matching temperature can be used as an excellent probe for the composition of LiNbO3.
Arsenic-doped P-type ZnTe grown by molecular beam epitaxy
Authors: Turco-Sandroff F. S. , Brasil M. J. S. P. , Nahory R. E. , Martin R. J. , Zhang Y. , Skromme B. J.
Published: July 2002

Efficient p doping of ZnTe by arsenic has been achieved using a Zn3As2 effusion cell. Doping levels of ZnTe/GaAs can be controlled from 1016 to 1018 cm−3. The carrier concentration is independent of the substrate used, ZnTe:As/GaAs and ZnTe:As/InP giving similar results. Spectral photoconductivity and low-temperature photoluminescence, however, show an increase of deep levels for doping levels higher than 1017 cm−3 but electrical measurements show no saturation for doping as high as 1018 cm−3.
Does benzene inhibit diamond film growth?
Authors: Martin L. Robbin , Harris Stephen J.
Published: July 2002

Experiments were conducted to test the hypothesis that aromatic molecules inhibit the growth of diamond thin films. Small amounts of benzene vapor were added to a flowtube system for diamond film growth. In this system, diamonds are grown by adding methane or acetylene to a flow of atomic hydrogen at 800 °C. Mass spectrometric measurements verified that the benzene passed through the flowtube. No inhibition of the growth rate or decrease in the quality of the diamonds due to the presence of benzene was observed for either methane or acetylene.
Low-temperature preparation of SiO2/Si(100) interfaces using a two-step remote plasma-assisted oxidation-deposition process
Authors: Yasuda T. , Ma Y. , Habermehl S. , Lucovsky G.
Published: July 2002

SiO2/Si(100) interfaces have been prepared by a low-temperature, 200–300 °C, remote plasma-assisted oxidation-deposition process. The oxidation: (i) creates ∼0.5 nm of SiO2; (ii) removes residual C from an otherwise H-terminated Si surface; and (iii) produces a SiO2/Si interface with a midgap trap density of ∼1×1010 cm−2 eV−1, and when combined with remote plasma-enhanced chemical vapor deposition (RPECVD) of SiO2, (iv) forms a SiO2/Si structure with properties comparable to those prepared by thermal oxidation of Si at 850–1050 °C.
Phase noise of four-wave mixing in semiconductor lasers
Authors: Hui Rongqing , Mecozzi Antonio
Published: July 2002

A simple theoretical analysis shows that the linewidth of the conjugate wave produced in four-wave mixing in semiconductor lasers is equal to the linewidth of the probe plus four times the linewidth of the pump. Experimental results in good agreement with the theory are presented. This result implies an enormous enhancement in the phase noise of the conjugate wave and sets a limitation on some practical applications of four-wave mixing.
Investigations of the Si3N4/Si/n-GaAs insulator-semiconductor interface with low interface trap density
Authors: Mui D. S. L. , Biswas D. , Reed J. , Demirel A. L. , Strite S. , Morkoç H.
Published: July 2002

We have investigated the interface properties of rapid thermal annealed in situ deposited gate quality Si3N4/Si/n-GaAs metal-insulator-semiconductor (MIS) capacitors. Conductance measurements show a minimum interface trap density of 1011 eV−1 cm−2 located in the lower-half of the GaAs band gap. The quasi-static capacitance-voltage (QSCV) curve shows the largest dip toward the high-frequency C-V curve ever observed in compound semiconductor-based MIS structures. In spite of the lowest interface trap density for GaAs-based MIS structures ever reported, conductance data reveal a rapid increase in the density of interface traps in the upper-half of the band gap. Both the ac loss and the capacitive frequency dispersion of the interface traps agree with the single time constant model. The anomalous frequency dispersion of the measured capacitance can be satisfactory explained by the trap location in the band gap and rapid increase in the trap density in the upper-half of the band gap.
Atmospheric photoassisted chemical vapor deposition of Si using ultraviolet-light irradiated H2 carrier gas and nonexcited SiH2Cl2
Authors: Mazumder Motaharul Kabir , Takakuwa Yuji , Miyamoto Nobuo
Published: July 2002

We have proposed a new photoassisted chemical vapor deposition (photo-CVD) process of Si, in which only a hydrogen carrier gas is excited by UV light from low-pressure Hg lamps and a reactant gas of SiH2Cl2 is not irradiated at all. In this type of photo-CVD, it is found that (1) the number of pyramidal hillocks on orientation-just surfaces is drastically suppressed, (2) the number of etch pits, corresponding to the stacking fault and the precipitation of contaminants, is also decreased, (3) the growth rate is significantly enhanced, and (4) the surface roughness is decreased. In particular it should be emphasized that these effects are more apparent at atmospheric pressure. It is suggested that the UV-light irradiated hydrogen plays an important role in removing chlorine atoms adsorbed on the surface.
Transmission electron microscopy study of diamond nucleation on 6H-SiC single crystal with possibility of epitaxy
Authors: Chang Li , Lin Tzer-Shen , Chen Jiun-Long , Chen Fu-Rong
Published: July 2002

Diamond has been grown on 6H-SiC single crystal wafers by microwave plasma assisted chemical vapor deposition with a negative bias pretreatment. A high nucleation density of diamond on the substrate has been achieved. Cross-sectional transmission electron microscopy was employed to study the interfacial microstructure of diamond on 6H-SiC. Lattice image observations illustrate that diamond is directly formed on the 6H-SiC substrate. The possibility of local epitaxial nucleation of diamond on the 6H-SiC substrate and its crystallography are briefly discussed.
Analysis of hydrogen diffusion from proton-exchanged layers in LiNbO3
Authors: Casey H. C. , Chen Chang-Ho , Zavada J. M. , Novak S. W.
Published: July 2002

Hydrogen profiles for proton-exchanged layers in Z-cut LiNbO3 were obtained by secondary ion mass spectrometry measurements after annealing at 400 °C for times from 6 to 180 min. To fit the measured hydrogen profiles, it was necessary to use two separate Gaussian diffusion profiles which could be designated as a more slowly diffusing substitutional hydrogen on lithium sites and a more rapidly diffusing interstitial hydrogen. At 400 °C, analysis leads to a substitutional hydrogen diffusion coefficient Ds≊4.6×10−12 cm2/s and an interstitial hydrogen diffusion coefficient Di≊1.5×10−11 cm2/s.
BaSi2 and thin film alkaline earth silicides on silicon
Authors: McKee R. A. , Walker F. J. , Conner J. R. , Raj R.
Published: July 2002

The epitaxial structural development and surface reactions of the alkaline earth metals with silicon have been studied as a function of surface coverage. The barium reaction has been characterized in detail from submonolayer structures to the thick film orthorhombic phase, BaSi2. From 0 to 1 monolayer a series of ordered surface structures develops that suggests a cubic Ba-Si compound. We have also shown that strontium, calcium, and magnesium develop these highly ordered submonolayer silicides. These submonolayer structures are the templates for the heteroepitaxial transition to alkaline earth containing oxides on silicon.
Temperature dependence of the direct band gap energy and donor–acceptor transition energies in Be-doped GaAsSb lattice matched to InP
Authors: Merkel K. G. , Bright V. M. , Marciniak M. A. , Cerny C. L. A. , Manasreh M. O.
Published: July 2002

The direct band energy (Eg) and donor–acceptor (D,A) transition energies are mapped as a function of temperature for Be-doped GaAsSb lattice matched to InP. Photoluminescence (PL) measurements over the temperature range 2 K≤T≤300 K yield two emission peaks, one of lower intensity and one of higher intensity. The lower intensity peak is believed to be Be related, while the higher intensity peak is from residual impurities. The emission energies of both PL peaks increase linearly with respect to the logarithm of excitation intensity, indicating the peaks are (D,A) transitions. Measurement of Eg was achieved using optical absorption spectroscopy over the range 14 K≤T≤300 K. A least squares fit of the absorption data using the Varshni equation produces a closed form expression for Eg(T) with coefficients α=13.5×10−4 eV/K, and β=135 K.
Temperature dependence of interband transitions in GaN grown by metalorganic chemical vapor deposition
Authors: Shan W. , Schmidt T. J. , Yang X. H. , Hwang S. J. , Song J. J. , Goldenberg B.
Published: July 2002

The interband transitions in single-crystal GaN films grown by metalorganic chemical vapor deposition (MOCVD) have been studied as a function of temperature (15≤T≤300 K) by reflectance and photoluminescence measurements. At low temperatures, well-resolved spectral features corresponding to the GaN band structure were observed. The energies of the excitonic interband ΓV9−ΓC7,ΓV7 (upper band)−ΓC7 and ΓV7(lower band)−ΓC7 transitions are found to be 3.485, 3.493, and 3.518 eV at 15 K, respectively, for the MOCVD GaN. The spectral features are broadened and shift to lower energy as temperature increases. At room temperature (300 K), the ΓV9−ΓC7and ΓV7 (upper band) −ΓC7 transition energies of this wide band-gap material are determined to be 3.420 and 3.428 eV, respectively. The temperature dependence of these two transitions have been determined using the Varshni empirical relation. Our results yield E0(T)=3.486–8.32×10−4 T2/(835.6+T) eV for the ΓV9−ΓC7 transition and E0(T)=3.494–10.9×10−4 T2/(1194.6+T) eV for the ΓV7 (upper band) −ΓC7 transition.
Ultra-low-threshold europium chelate laser in morphology-dependent resonances
Authors: Taniguchi Hiroshi , Tomisawa Humihiro , Kido Junji
Published: July 2002

We show ultra-low-threshold lasing due to morphology-dependent resonances from an europium (Eu)-chelate-doped microdroplet with ∼90 μm diameter. Spectra and spatial images between lasing and nonlasing are exhibited with comparison. Temporal responses are discussed from the viewpoint of the faster (direct) and slower (indirect) transitions in Eu chelates.
Grid effects on velocity analyzers of variable geometry
Authors: Donoso Guillermo , Martin Pablo
Published: July 2002

A complete theory of a planar electrostatic velocity analyzer is developed for the case of a discriminating grid composed of parallel cylindrical wires. Exact solutions for the potential distribution inside the analyzer and for the depletion of the discriminating potential in the grid plane are calculated by means of a Schwarz–Christoffel transformation. It is shown that the dependence of the collector current on the discriminating voltage deviates from the simple exponential law. The analysis shows the following effects: a stretching and displacement of the V axis of the characteristics and a decrease of the collector saturation current. A new expression to calculate the plasma temperature from the characteristic curve is given.
Reservoir-type liquid metal ion source of Al
Authors: Yamada Hiroshi , Torii Yasuhiro
Published: July 2002

A liquid metal ion source of Al with a boride reservoir was developed. In this reservoir a shorter boride emitter was designed to overcome the brittleness of boride materials and some problems in supplying the Al material. This source makes possible a long continuous operation time and enhanced reliability. The fundamental performance characteristics did not change after 250 h of operation. A stable Al ion beam emission was obtained for more than 500 h and its current fluctuation was less than ±1%/3 h for a 20–30-μA source ion current. The energy spread was less than 9 eV (FWHM) for a 30-μA/sr angular current intensity.
Sources of error in dynamic applications of electronic displacement sensors
Authors: Lazzarini Albert
Published: July 2002

Sources of intrinsic limitations in the use of electromagnetic displacement transducers (capacitive and inductive) are investigated. These limitations arise from effects caused by motion of the transducer’s electromagnetic field due to its own displacement. At sufficiently high-mechanical frequencies such motions modify in a nonlinear manner the output characteristics of the transducers and produces dynamic hysteresis effects.
Digital back off for computer controlled flash spectrometers
Authors: Davis Frank S. , Nemeth Gregory A. , Anjo Dennis M. , Makings Lewis R. , Gust Devens , Moore Thomas A.
Published: July 2002

A digital software-controlled back-off system for probe lamp dc signal nullification has been designed and incorporated into a laser flash photolysis spectrometer. This method takes advantage of modern high-speed operational amplifiers already employed in the detection circuitry and the dedicated small computer that runs the spectrometer. The determination of I0, necessary for absorbance calculations, is inherent in the method.
Differential dielectric-to-density measurement for cryogenic fluids
Authors: Liu F. F. , Chow S. W. H.
Published: July 2002

A high-speed microprocessor-based cryogenic fluid density instrumentation is developed based on the rigorous application of dielectric theory, using a dielectric susceptibility function in the application of molecular Clausius–Mossotti formula. The operating principle is formulated on a novel differential dielectric measurement approach with a new algorithm which provides for automatic adjustments for polarizability and stray capacitance changes. High-precision digital density measurement is achieved over a wide range of fluid state ranging from supercritical, through subcritical to solid formation phases. Its conceptual development is examined in view of the interplay between theoretical arguments and engineering methodology.
Rapid densification of porous carbon–carbon composites by thermal-gradient chemical vapor infiltration
Authors: Golecki I. , Morris R. C. , Narasimhan D. , Clements N.
Published: July 2002

Porous carbon–carbon preforms, 10.8 cm o.d.×4.4 cm i.d.×3.0 cm thick have been densified in a one-cycle, 26 h process. The disks are heated by induction, creating an inside-out thermal gradient, and are exposed to cyclopentane vapor in a water-cooled vacuum chamber. Rough-laminar carbon microstructure is obtained; a compressive strength of 268 MPa is measured at 1.79 g/ cm3 density. The densification rate is monitored in real time. The precursor utilization efficiency is 20%–30%. Our patented process can be applied to other materials, has significant scale-up potential and is economically competitive.