bluuebunny/crossref_metadata_2025 huggingface dataset:
Phytochemical & Pharmacological Activities of Diospyros malabarica
Authors: Himi Afnan Sayeid , Pramanik Manik , Kubra Khadizatul , Muntaher Maisha , Anika Khandaker Antara , Islam Md. Ariful , Mia Md. Sagar
Published: February 2025

Diospyros malabarica, is a prominent member of the Ebenaceae intimate natural to the Indian subcontinent. This paper comprehensively explores the diverse pharmacological activities attributed to various parts of Diospyros malabarica, shedding light on its possible as a foundation of bioactive composites for medicinal and therapeutic applications. The pharmacological properties of Diospyros malabarica are presented through an in-depth analysis of the scientific literature, highlighting its traditional uses, phytochemical constituents and therapeutic potential. This paper covers the wide array of bioactive compounds identified in Diospyros malabarica, which have been linked to its various pharmacological activities. Several studies have demonstrated its antimicrobial, antioxidant, anti-inflammatory, anti-diarrheal, anthelminthic and anti-diabetic properties. Additionally, Diospyros malabarica has shown promise as an anticancer agent, with its extracts exhibiting cytotoxic effects on various cancer cell lines. Furthermore, the paper underscores the importance of supplementary exploration to better understand the mechanisms of fundamental in the experimental pharmacological activities and to develop standardized formulations for clinical use. Diospyros malabarica emerges as a valuable botanical resource with rich pharmacological potential. Its traditional uses are supported by scientific evidence and its bioactive compounds hold promise for the development of novel therapeutic agents.
Contribution of Molecular Methods to Reduce the Burden of Antimicrobial Resistance
Authors: Aduah Martin , Duyann Zawu Yoowa , Chisapo Gift Herrings , Jerry Oni Gbotemi , Wurie Ahmed Wopa , Abolarinwa Esther Opeyemi
Published: February 2025

This review seeks to address the various approaches adopted to combat this phenomenon. With scientific facts, latter era has been proven that antibiotics have drastically transformed the way we treat infections nowadays due to several factors that strongly need to be carefully look into for preventive purposes. There are several vital tools for up-to-date medication; nonetheless, inappropriately, their misappropriation has led to the development of bacteria that are resistant to antibiotics. Essentially, excessive prescription has broad-spectrum antibiotics, rather than a more precisely targeted antibiotic based on accurate diagnosis, coupled with patient non-adherence to prescribed dosage and duration, contributes to bacterial survival and subsequent resistance. Several research materials have indicated that bacteria in meat have revealed antibiotic-resistant presence including other food products. Conventional approaches such as prudent use of available antibiotics, one of the ways is avoidance complete suitable immunization, disinfected precautions awareness will greatly aid in the control of cross-transmission of resistant straining among persons; including appropriate screening for resistant strains and separation of carrier patients in order to avoid the spread of the infection. Additionally, updated scientific research and development of antibiotics exercises with accurate innovative mechanism of action were analysed. Furthermore, genomic techniques that have been used to address antimicrobial resistance (AMR) by tracking and analysing the genetic makeup of bacteria are also reviewed. These techniques have been used to identify the genetic mutations that cause AMR, track the spread of resistant strains, and develop new treatments.
Streptococcus agalactiae: Vaginal Carriage, Associated Risk Factors and Antibiotic Susceptibility in Pregnant Women Received at Ouakam Military Hospital Laboratory, Senegal
Authors: Gueye Papa Aly Thiam , Faye Cheikh , Ndoye Aissatou Sow , Engo Pasca Elie , Ba Mame Diarra , Aïdara Souleymane , Mbow Moustapha , Seck Mame Cheikh
Published: February 2025

Introduction: Streptococcus agalactiae or Group B Streptococcus (GBS) is a commensal bacterium of the female reproductive tract that can be pathogenic in newborns. The objectives of this present study were: to determine the rate of vaginal carriage of GBS in pregnant women, the associated risk factors and to evaluate antibiotic resistance.
Methodology: We conducted a prospective, descriptive, analytical study in the medical biology laboratory of Ouakam Military Hospital from July 1, 2022 to June 30, 2023. Identification and antibiotic susceptibility testing were performed using the Vitek 2 COMPACT automated system (bioMérieux). Statistical analysis was performed with RStudio software (version 4.3.2) and differences were considered significant if p<0.05.
Results: We received 327 pregnant women with a mean age of 31.8 ± 5.4 years. Vaginal GBS carriage was 17.74% (58/327), higher in women aged 26-35 years (70.69%), in the third trimester of pregnancy (46.6%), primiparous (46.6%), university-educated (44.8%) and having used contraception at least once (67.2%). It was higher in those with non-fetid leucorrhoea (53.4%), local inflammation (53.4%), local symptoms (67.2%), balanced vaginal flora (75.9%), use of a disposable pad (61.5%), and no previous abortion (58.6%). However, none of these factors was significantly associated with vaginal GBS carriage (p>0.05). There was no resistance to vancomycin, tigecycline, teicoplanin, linezolid and daptomycin, while tetracycline was the least active molecule.
Conclusion: The rate of vaginal carriage of GBS in the pregnant women in our study was relatively high, with no significantly associated risk factors. Non-negligible resistance to penicillin G was noted. However, vancomycin, tigecycline, teicoplanin, linezolid and daptomycin could be therapeutic alternatives.
Lack of correlation between mRNA expression and enzymatic activity of the aspartate aminotransferase isoenzymes in various tissues of the rat
Authors: Abruzzese F. , Greco M. , Perlino E. , Doonan S. , Marra E.
Published: July 2002

Little is known about control of expression of basal levels of the aspartate aminotransferases which are ubiquitous ‘house keeping’ enzymes in vertebrates. We have measured both mRNA and activity levels for both isoenzymes in various rat tissues as a function of age. Patterns of mRNA expression for the two isoenzymes were similar in a particular tissue about differed widely between tissues. Surprisingly, there was no simple correlation between mRNA levels and specific activities of the enzyme products. We conclude that translation for mRNA for these two isoenzymes is subject to tissue‐specific, and in some cases age‐related, regulation.
Protein‐mediated protein maturation in eukaryotes
Authors: Haas Ingrid G.
Published: July 2002

Eukaryotic cells have developed particular strategies to support the critical steps in protein maturation that starts in the cytosol with the birth of a nascent polypeptide chain, and ends when the protein has reached the appropriate compartment and/ or has attained its mature structure. Many of the cellular proteins that have evolved to promote maturation processes are constitutively expressed members of the highly conserved heat shock protein (hsp) family, also known as “molecular chaperones”. Protein‐mediated processes that occur in the cytosol are discussed.
Low‐dose vaginal misoprostol for induction of labor with a live fetus
Authors: Bugalho A. , Bique C. , Machungo F. , Faúndes A.
Published: July 2002

Objective: To test the effectiveness and safety of low‐dose vaginal misoprostol for induction of labor with a live fetus. Methods: Labor was induced in 666 pregnant women with a live fetus in the cephalic position, who had no medical complications and no history of uterine surgery. One‐fourth of a 200‐μg tablet of misoprostol (50 μg) was placed in the posterior vaginal fornix every 12 h for a maximum of four doses or until active labor commenced. Time from induction to delivery, side effects and neonatal outcome were evaluated. Results: Labor was successfully induced in all cases. The mean time from induction to delivery was 10.4 h. The cesarean section rate was 7.8%. There were eight perinatal deaths, six of which occurred in low birth weight fetuses. There was one case of abruptio placenta, which was less than that expected in the study population. Conclusion: Vaginal misoprostol, in very low doses, was a remarkably efficient and safe method for induction of labor with a live fetus.
Polymorphism in codon 17 of the CTLA‐4 gene (+49 A/G) is not associated with susceptibility to rheumatoid arthritis in British Caucasians
Authors: Milicic A. , Brown M.A. , Wordsworth B.P.
Published: July 2002

Abstract: The role of the CTLA‐4 antigen in the development of autoimmune diseases is well documented, with several autoimmune disorders showing association or linkage with the CTLA‐4 locus. Its role in the aetiology of rheumatoid arthritis (RA) however, remains unclear, as the functional studies of the B7‐CTLA‐4 pathway in mouse models of RA and genetic studies in humans have given contrasting results. We have studied the single nucleotide polymorphism at position +49 (A/G) of the CTLA‐4 gene, in a cohort of 421 RA cases and 452 healthy controls from the UK. Despite the high statistical power to detect even a weak susceptibility effect, no significant association was found. We also analysed the distribution of the allele and genotype frequencies with respect to the presence of the shared epitope (a known RA susceptibility factor) and found no statistically significant differences. We conclude that, although the importance of the B7‐CTLA‐4 interaction in the development of RA can not be excluded, the CTLA‐4 gene is unlikely to be a predisposing factor to this disease.
Phosphatidylinositol transfer protein β displays minimal sphingomyelin transfer activity and is not required for biosynthesis and trafficking of sphingomyelin
Authors: SÉGUI Bruno , ALLEN-BAUME Victoria , COCKCROFT Shamshad
Published: July 2002

Mammalian phosphatidylinositol transfer proteins (PITPs) α and β, which share 77% identity, have been shown to exhibit distinct lipid-transfer activities. In addition to transferring phosphatidylinositol (PI) and phosphatidylcholine (PC), PITPβ has been shown to transfer sphingomyelin (SM), and this has led to the suggestion that PITPβ is important for the regulation of SM metabolism. In the present study, we have analysed the ability of human PITPβ to transfer and regulate the metabolism of cellular SM. We report that, in vitro, the two PITP isoforms were comparable in mediating PI, PC or SM transfer. Using permeabilized HL-60 cells as the donor compartment, both PITP isoforms efficiently transferred PI and PC, and were slightly active towards SM, with the activity of PITPβ being slightly greater. To identify which cellular lipids were selected by PITPs, PITPα and PITPβ were exposed to permeabilized HL-60 cells, and subsequently repurified and analysed for their bound lipids. Both PITPs were able to select only PI and PC, but not SM. SM synthesis takes place at the Golgi, and PITPβ was shown to localize in that compartment. To examine the role of PITPβ in SM biosynthesis, Golgi membranes were used. Purified Golgi membranes had lost their endogenous PITPβ, but were able to recruit PITPβ when added exogenously. However, PITPβ did not enhance the activities of either SM synthase or glucosylceramide synthase. Further analysis in COS-7 cells overexpressing PITPβ showed no effects on (a) SM and glucosylceramide biosynthesis, (b) diacylglycerol or ceramide levels, (c) SM transport from the Golgi to the plasma membrane, or (d) resynthesis of SM after exogenous sphingomyelinase treatment. Altogether, these observations do not support the suggestion that PITPβ participates in the transfer of SM, the regulation of SM biosynthesis or its intracellular trafficking.
Sexual differences in moult–breeding overlap and female reproductive costs in pied flycatchers, Ficedula hypoleuca
Authors: Hemborg Christer.
Published: July 2002

1. In this study I show that a sexual difference in timing of the post‐nuptial moult frequently occurs in a sub‐arctic population of the pied flycatcher.

2. Most pairs started to moult after fledging of their young, but an overlap between moult and nestling feeding was more common among males than females. This sexual difference in moult–breeding overlap increased as the season progressed.

3. Females with moult–breeding overlap laid smaller clutches than non‐moulting females. In addition to many other factors explaining the seasonal decline in clutch size that has been found for many bird species, it is possible that females adjust their clutch size according to their own risk of having to start moulting while still feeding the nestlings.

4. Nearly 24% of the females were deserted by their mate before the young fledged. Desertion imposed no fitness costs to males in terms of fledgling number or quality, suggesting that their females managed to adjust their care for the loss of male care.

5. Deserted females started moulting later than aided females, which may be a result of their increased reproductive investment.

6. Deserted females and females aided by moulting males had lower survival rate than females aided by non‐moulting males.

7. These findings suggests that delayed moult may be one mechanism causing inter‐annual reproductive costs in birds, and the relationship between a sexual difference in timing of moult and its fitness consequences may be widespread among passerine birds.
The effect of rainfall on the survivorship and establishment of a biocontrol agent
Authors: Norris R.J. , Memmott J. , Lovell D.J.
Published: July 2002

The weather is believed to affect the establishment of insect biological control agents in the field, in particular heavy rainfall immediately after release, but few studies have quantified this impact.

A rain simulator was used to quantify the effect of rainfall duration and intensity on the post‐release survivorship of a gorse biological control agent, the thrips Sericothripsstaphylinus. This information was then used to predict the effect of rainfall on the establishment of thrips in the field.

Rainfall significantly decreased the numbers of thrips remaining on the plants, but significantly increased the numbers of thrips found dead and missing. As rain duration increased, the numbers of thrips remaining on the plants decreased. However, the relationship was not linear: the majority of thrips were washed off the plants within 30 min of the 120‐min experiment.

Thrips survivorship was significantly affected by rainfall intensity (moderate, heavy and violent rainfall). Increasing rainfall intensity caused a significant decrease in the numbers of thrips remaining on the plants and significant increases in the numbers missing or found dead.

The relationship between rainfall, thrips release size and their probability of establishment was determined by combining published data on their probability of establishment with the results of our experiments. Rainfall is likely to change the relationship between the release size and the probability of establishment.

We advocate that biological control practitioners should be cognisant of weather conditions prior to any release. Control agents at risk from rain might be released in protective cages, while smaller sequential releases might be preferable to single large releases if adverse conditions are likely. This study demonstrates the value of controlled environments in understanding the effects of weather on biocontrol, and for invasion ecology more generally.
Children at play: The death and injury pattern in New South Wales, Australia, July 1990 – June 1994
Authors: Ross LT LAM, FI , Cass DT
Published: July 2002

Objectives: To describe and to understand the pattern of play‐related deaths and injury (excluding organized sports) among children in New South Wales (NSW), Australia.

Methodology: This study utilized a state‐wide prospective surveillance data collection of paediatric traumatic deaths and injuries at the Royal Alexandra Hospital for Children. Deaths and injury cases were selected from the NSW Trauma Death Registry and Childsafe NSW database. Information including basic demographics, the surrounding circumstances of death and injury incidents, and the required treatment was collected.

Results: There were 30 play‐related deaths and 92 drownings over the 4‐year period. The male to female ratio was about 2:1. Excluding drowning, which has been reported elsewhere, and sports, the leading causes of play‐related deaths were burns (eight) and asphyxiation (eight). An average of 6444 presentations to the emergency departments per year were recorded with sex ratio and age distribution pattern similar to the deaths. The home was the most common place (55.5%) of play‐related injury, specifically the living and sleeping area. Falls, both under and above 1 metre, were the most common causes of injury (50.9%). The leading mechanism was cuts and lacerations (21.2%). Nearly one‐third (32.7%) of all injuries were to the head, with face, cheek, forehead and scalp as the most common injured body part. Significant associations between place of injury, injured body parts and age were observed.

Conclusions: Play‐related injury is common among children, and in some cases causes severe injury and death. To tackle the problem of play‐related deaths and injuries, a holistic approach is suggested. This includes the provision of a safe environment, supervision by parents, education of children and detailed data collection.
Contact resistivity of some magnesium/silicon and magnesium silicide/silicon structures
Authors: Janega P. L. , McCaffrey J. , Landheer D. , Buchanan M. , Denhoff M. , Mitchel D.
Published: July 2002

Transmission line model and end resistance measurements were made to determine the contact resistivity of Mg and Mg2Si contacts to Si doped n-type in the range 1018–1020 cm−3. The data are consistent with a barrier height of 0.4 eV for Mg and 0.52 eV for Mg2Si. The morphology, structure, and composition were studied using transmission electron microscopy.
Formation of nickel silicides in the Ni/Si3N4/Si system during rapid thermal annealing
Authors: Edelman F. , Gutmanas E. Y. , Katz A. , Brener R.
Published: July 2002

Effect of rapid thermal annealing (RTA) at 800, 1000, and 1200 °C on the Ni/Si3N4/Si system has been studied employing electron microscopy, Auger electron spectroscopy, and x-ray diffraction analysis. Formation of NiSi or NiSi2 silicides on the Ni/Si3N4 interface and of NiSi2 silicide on the Si3N4/Si interface was observed after RTA. This was a result of the diffusion of Si into deposited 250-nm-thick Ni layer and the diffusion of Ni through 140-nm-thick amorphous Si3N4 layer into the Si substrate. The diffusion coefficient of Ni in amorphous Si3N4 was estimated to be D≂103 exp(−3.2 eV/kT), cm2/s.
Oscillator strength of ruby R1 line under high pressure
Authors: Sharma Surinder M. , Gupta Y. M.
Published: July 2002

A recently observed rapid decrease in oscillator strength of 2E(Ē)→4A2 (R1 line) of ruby with static pressure is quantitatively explained with the help of other observed spectral shifts and a scaling procedure used earlier to model wavelength shifts with pressure. Oscillator strength is also predicted to decrease for R′ lines, but for B lines it increases with pressure.
Laser-induced chemical vapor deposition of aluminum
Authors: Baum Thomas H. , Larson Carl E. , Jackson Robert L.
Published: July 2002

The laser-induced deposition of high-purity aluminum metal has been achieved by pyrolytic decomposition of trimethylamine aluminum hydride. The chemical structure of the precursor affords a high ambient vapor pressure which results in rapid rates of aluminum film formation. In addition, the precursor is nonpyrophoric, in contrast to other trialkylaluminum precursors. These combined chemical and physical properties make trimethylamine aluminum hydride an ideal precursor for laser-induced chemical vapor deposition of aluminun films.
Photothermal measurements of high T
c superconductors
Authors: Fanton J. T. , Mitzi D. B. , Kapitulnik A. , Khuri-Yakub B. T. , Kino G. S. , Gazit D. , Feigelson R. S.
Published: July 2002

We demonstrate a photothermal method for making point measurements of the thermal conductivities of high Tc superconductors. Images made at room temperature on polycrystalline materials show the thermal inhomogeneities. Measurements on single-crystal Bi2Sr2CaCu2Ox compounds reveal a very large anisotropy of about 7:1 in the thermal conductivity.
Fabrication of thin-film metal nanobridges
Authors: Ralls K. S. , Buhrman R. A. , Tiberio R. C.
Published: July 2002

Thin-film fabrication techniques for forming three-dimensional ‘‘point contacts’’ are presented. As-fabricated nanobridges can be modified using electromigration to make the constriction region smaller or dirtier. Scientific applications to quantum transport studies, 1/f noise, and electromigration are discussed.
Pyrolysis of trimethylgallium on GaAs(100) surfaces
Authors: Memmert Ulrich , Yu Ming L.
Published: July 2002

We have used a combination of pulsed molecular beam and time-resolved mass spectrometry to study the kinetics of the pyrolysis of trimethylgallium on GaAs(100) surfaces. We found that CH3 is the major reaction product. Two CH3 desorption channels were observed, with activation energies 37.9±1.6 and 45.0±1.4 kcal/mole. An arsine ambient significantly accelerates the CH3 desorption, but no CH4 was observed. A model for the reaction of trimethylgallium on the GaAs(100) surface is proposed.
Sideband development in a high-power traveling-wave tube microwave amplifier
Authors: Shiffler D. , Ivers J. D. , Kerslick G. S. , Nation J. A. , Schachter L.
Published: July 2002

The work presented describes the characteristics of single stage and severed high-efficiency, high-power traveling-wave tube amplifiers operating in X band at 8.76 GHz. Average amplified output powers of 210 MW have been achieved at 24% efficiency. At high output power levels (≳100 MW) sidebands develop increasing the average radiated power to over 400 MW with a microwave conversion efficiency of over 45%. In single frequency operation phase stability to within ±8° has been demonstrated.
Effect of hot-pressing temperature on the optical transmission of zinc sulfide
Authors: Xue Liang A. , Raj Rishi
Published: July 2002

Two phase mixtures of ZnS consisting of the hexagonal and the cubic phase have been prepared by hot-pressing at different temperatures. The optical properties of these two phase composites were measured in the far infrared. The difference in the index of refraction between the cubic and the hexagonal phases produced scattering that was accentuated at large grain size. The results are correlated with the fourth power dependence of the scattering cross section on the grain size.
Quantum well waveguide intensity modulator at visible wavelengths using CdZnTe/ZnTe quantum wells
Authors: Lee D. , Zucker J. E. , Divino M. D. , Austin R. F. , Feldman R. D. , Jones K. L. , Johnson A. M.
Published: July 2002

We demonstrate the first waveguide intensity modulator for visible wavelengths based on the quantum-confined Stark effect. The active waveguide core is composed of 58 Cd0.42Zn0.58Te/ZnTe quantum wells surrounded by Cd0.12Zn0.88Te cladding layers. We obtain ≳10 dB modulation depth at 640 nm with 4 V bias in a 500-μm-long waveguide.
Infrared absorption and photoconductive gain of quantum well infrared photodetectors
Authors: Choi K. K. , Fotiadis L. , Taysing-Lara M. , Chang W. , Iafrate G. J.
Published: July 2002

We have conducted a detailed study on the properties of a multiple quantum well infrared photodetector (QWIP) with a single bound state. From the optical absorption experiment, we found that the peak absorption energy is determined by the resonant states associated with each individual well and not by the global miniband structure. From the transport experiment, we observed that the photoelectron distribution over the QWIP is extremely narrow and close to the top of the quantum well barriers, indicative of the diffusive nature of the hot-electron transport in this structure. At large bias, the photoelectron distribution begins to shift up in energy, and is found strongly correlated to the observed photoconductive gain of the detector.
Thermal nitridation of silicon in a cluster tool
Authors: Delfino M. , Fair J. A. , Salimian S.
Published: July 2002

An integrated cluster tool process is described whereby stoichiometric Si3N4 films with less than 0.01 at % oxygen, hydrogen, and carbon are grown on 〈111〉 Si. The ultrahigh film purity is verified in situ with x-ray photoelectron spectroscopy and static secondary ion-mass spectrometry depth profiles. The two-step process consists of cleaning the surface in an electron cyclotron resonance excited H2 plasma, and passing in vacuum to a second chamber where it is exposed to NH3 for 2 min at 1070 °C to promote nitridation. The films are approximately 5 nm thick with a refractive index of 2.01 at 633 nm. They are resistant to a dry O2 ambient for at least 6 h at 1050 °C. The average breakdown field of Al/Si3N4/Si capacitors is around 9 MV/cm.
Third-order nonlinear optical response in polymer thin films incorporating porphyrin derivatives
Authors: Norwood R. A. , Sounik J. R.
Published: July 2002

The third-order nonlinear optical properties of several porphyrin derivatives incorporated in thin films of polymethylmethacrylate have been measured by degenerate four-wave mixing at 598 nm with 1 ps pulses. Both the magnitude and dynamics of the nonlinear response are measured, with each system exhibiting both a subpicosecond response and a more slowly decaying response (10 ps–1 ns) owing to excited-state population. A copolymer of silicon phthalocyanine and methyl methacrylate exhibits a fast recovery time (15 ps) and no observable long-time (∼ns) component of its nonlinear response, as well as an absorption band twice as narrow as that of guest/host samples of the same material.
Electrical characterization to 4 THz of N- and P-type GaAs using THz time-domain spectroscopy
Authors: Katzenellenbogen N. , Grischkowsky D.
Published: July 2002

Using a high-performance optoelectronic THz beam system for time-domain spectroscopy, we have measured the absorption and index of refraction of N- and P-type doped GaAs from low frequencies to 4 THz. From these measurements the complex conductance was obtained over the same frequency range. All of the results were well fit by Drude theory.
Second harmonic generation at 972 nm using a distributed Bragg reflection semiconductor laser
Authors: Zimmermann C. , Hänsch T. W. , Byer R. , O’Brien S. , Welch D.
Published: July 2002

We have doubled the frequency of a single mode distributed Bragg reflection (DBR) semiconductor laser. The laser is optically locked to an external enhancement ring resonator that contains an antireflection coated potassium niobate crystal. Unlike Fabry–Perot cavity lasers the DBR laser is found to operate in only one longitudinal mode and allows stable second harmonic generation. We present the results obtained with a singly and doubly resonant cavity. A total output of 1.2 mW tunable single mode radiation near 486 nm has been generated from a laser output power of 25 mW at 972 nm without the use of optical isolators or active feedback control.
High current density produced by femtosecond nonlinear single-photon photoelectric emission from gold
Authors: Girardeau-Montaut J. P. , Girardeau-Montaut C. , Moustaizis S. D. , Fotakis C.
Published: July 2002

The sensitivity of single-photon photoelectric emission of pure-polycrystalline Au induced by a KrF excimer laser emitting at 248 nm pulses of 450 fs duration, has been measured. A nonlinear increase of photoelectric efficiency as a function of the laser peak intensity has been observed. The threshold of this nonlinearity is estimated from the experimental data to be slightly less than 0.1 GW/cm2. This value is in good agreement with earlier observations for W and Zr. We demonstrate that this is the direct consequence of nonequilibrium electron and lattice temperatures produced at the surface by the subpicosecond laser pulses.
Domain inversion in heat-treated LiNbO3 crystals
Authors: Kugel V. D. , Rosenman G.
Published: July 2002

A new microscopic mechanism of a domain reversal in outdiffused LiNbO3 is proposed. Computer results are in good agreement with experimental data.
Graded band-gap Cu(In,Ga)Se2 thin-film solar cell absorber with enhanced open-circuit voltage
Authors: Contreras Miguel , Tuttle John , Du Dahong , Qi Yi , Swartzlander Amy , Tennant Andrew , Noufi Rommel
Published: July 2002

An important development in polycrystalline Cu(In,Ga)Se2 (CIGS) thin-film photovoltaic solar cells is the attainment of a high voltage device simultaneous with state-of-the-art conversion efficiency. This letter describes a CIGS-based solar cell that demonstrates an open-circuit voltage (Voc) approaching 700 mV and a total-area conversion efficiency of 12.2%. The high value of Voc was achieved by grading In/Ga through the absorber by a computer-controlled physical vapor deposition (PVD) process that utilizes variable metal fluxes.
Substrate temperature effect on giant magnetoresistance of sputtered Co/Cu multilayers
Authors: Kano H. , Kagawa K. , Suzuki A. , Okabe A. , Hayashi K. , Aso K.
Published: July 2002

The relation between giant magnetoresistance (GMR) and the substrate temperature was investigated in sputtered Co/Cu multilayers. The magnetoresistance (MR) ratio is increased as the substrate temperature is decreased. The increase in the MR ratio is considered to be caused by the improvement in the sharpness of interfaces as concluded from the satellite peak intensity of the x-ray diffraction. The rough interfaces reduce the antiferromagnetic coupled areas and result in the MR ratio decrease. By lowering the substrate temperature to 20 °C, the MR ratio of 80% at room temperature was obtained.
Sm:YAG optical pressure sensor to 180 GPa:Calibration and structural disorder
Authors: Liu Jun , Vohra Yogesh K.
Published: July 2002

We report ultrahigh pressure calibration and fluorescence intensity measurements of Sm:YAG to 180 GPa in a diamond anvil cell at room temperature. Several fluorescence emission bands excited by argon ion laser were followed with increasing pressure and it was observed that Y4 band was the most intense in the pressure regime of 100–180 GPa. The Y4 band is calibrated against the R band of ruby to 180 GPa. Irreversible changes in the line intensities above 100 GPa were observed in Sm:YAG and quenched to ambient pressure. Linewidths of the fluorescence bands of the quenched phase indicate structural disorder. In contrast to ruby pressure sensor, the Y4 emission band of Sm:YAG is easily detectable at ultrahigh pressures.
Observation of voids induced by mechanical stress and electromigration in passivated Al lines deposited at different purity levels
Authors: Marieb T. , Bravman J. C. , Flinn P. , Gardner D. S. , Madden M.
Published: July 2002

Two pure Al passivated line samples were prepared under different metal deposition conditions, and were electromigration tested in a high voltage scanning electron microscope (HVSEM). The sample prepared under ultrahigh purity conditions showed a high resistance to void initiation and a very large grain size, while the more conventionally deposited metal displayed comparatively poor electromigration resistance. The sample prepared at lower purity conditions showed initial stress voids, but these were not the site for electromigration damage.
Evidence of donor–acceptor pair recombination from a new emission band in semiconducting diamond
Authors: Freitas J. A. , Klein P. B. , Collins A. T.
Published: July 2002

Steady state and time resolved photoluminescence studies of type IIb boron-doped synthetic diamond reveal a new broad red emission band that exhibits many of the features of classic donor–acceptor pair recombination. This recombination is thought to be between an as-yet unidentified neutral donor, possibly nitrogen related, approximately 3.6 eV below the conduction band edge and neutral boron acceptors at 0.37 eV above the valence band edge.
Sputter deposited strontium ferrite films with c-axis oriented normal to the film plane
Authors: Acharya B. Ramamurthy , Krishnan R. , Prasad Shiva , Venkataramani N. , Ajan Antony , Shringi S. N.
Published: July 2002

M-type strontium ferrite films were deposited by radio-frequency (rf) sputtering on fused quartz substrates kept at ambient temperatures. The as-deposited films were amorphous. They crystallized on annealing at a temperature of 800 °C or higher. The films deposited at low rf power and low oxygen to argon ratio showed c-axis orientation normal to the film plane. The magnetic properties of these films were studied using vibrating sample magnetometer, polar Kerr rotation, and torque magnetometer. The perpendicular M-H loops for c-axis oriented films were nearly rectangular with coercivity of the order of 3 kOe.
Thermal quenching properties of Er-doped GaP
Authors: Wang X. Z. , Wessels B. W.
Published: July 2002

The photoluminescent properties of the Er-doped epitaxial layers of GaP prepared by metalorganic vapor phase epitaxy were studied as a function of temperature. Strong characteristic Er3+ intra-4f-shell emission is observed over the temperature range of 12–300 K. The integrated intensity of the 0.805-eV emission is only weakly temperature dependent, decreasing by a factor of 2 as the temperature increases from 12 to 300 K. The observation of minimal thermal quenching indicates that Er-doped GaP is a promising material for optical devices emitting at 1.54 μm and operating at room temperature.
Efficient blue electroluminescence from a fluorinated polyquinoline
Authors: Parker I. D. , Pei Q. , Marrocco M.
Published: July 2002

High efficiency blue electroluminescence is demonstrated from a polyquinoline ether, a new class of soluble, electroluminescent, polyaromatic polymer. Multilayer devices (consisting of hole and electron transport layers in addition to the emissive polyquinoline layer) show an internal quantum efficiency in excess of 4% at 450 nm. Light emitted from these devices is easily visible in room light with luminence levels of 30 cd/m2 at 55 V with a current density of 9 mA/cm2. The transport layers are shown to serve a dual function—to modify the carrier injection properties and to block passage of carriers of the opposite polarity thereby trapping carriers in the emissive layer.
Perpendicular giant magnetoresistance of Co/Cu multilayers deposited under an angle on grooved substrates
Authors: Gijs M. A. M. , Johnson M. T. , Reinders A. , Huisman P. E. , van de Veerdonk R. J. M. , Lenczowski S. K. J. , van Gansewinkel R. M. J.
Published: July 2002

We propose a novel experimental technique for investigating the giant magnetoresistance effect measured with the current perpendicular to the layer plane (the so-called CPP geometry). Using holographic laser interference nanofabrication techniques and anisotropic etching the surface of semi-insulating InP substrates is patterned into V-shaped grooves of 0.2 μm width. Subsequently, a magnetic multilayer can be evaporated under an angle with the substrate normal, naturally resulting in a CPP-like magnetoresistance configuration. The technique is illustrated for Co/Cu multilayers, for which we present magnetization and magnetoresistance experiments.
Perpendicular current magnetoresistance in Co/Cu/NiFeCo/Cu multilayered microstructures
Authors: Vavra W. , Cheng S. F. , Fink Anita , Krebs J. J. , Prinz G. A.
Published: July 2002

An approach is demonstrated for lithographic fabrication of perpendicular current magnetoresistance devices which avoids the necessity of postprocess ‘‘trimming’’ of electrical leads. Magnetoresistance properties are investigated as a function of device size, magnetic layer thickness, and temperature. It is found that in some cases the current distribution in the microstructures change substantially with temperature resulting in a negative temperature coefficient of resistivity. It is also shown that the devices’ own magnetic fields have a dramatic effect on magnetoresistance properties.
Normal-incidence grating spectrograph with large acceptance for inverse photoemission
Authors: Fauster Th. , Straub D. , Donelon J. J. , Grimm D. , Marx A. , Himpsel F. J.
Published: July 2002

A spectrometer for inverse photoemission in the vacuum ultraviolet range is described. A spherical grating with an acceptance of f/4 is used in normal incidence. Two position-sensitive detectors allow the registration of spectra covering the whole range of photon energies from 8 to 28 eV in parallel. The optical resolution is 18 Å for the Lyman-α line of hydrogen. A space-charge-limited electron gun with an energy spread of 0.25 eV is used to excite inverse photoemission spectra. The large acceptance angle of the grating allows one to measure spectra with high efficiency and low background level.
Magnetic field measurements based on the Zeeman splitting of forbidden transitions
Authors: Seely J. F. , Feldman U. , Sheeley N. R. , Suckewer S. , Title A. M.
Published: July 2002

The measurement of the poloidal magnetic field in a tokamak plasma from the Zeeman splitting and polarization of the magnetic dipole radiation from heavy ions is discussed. When viewed from a direction perpendicular to the toroidal field, the effect of the poloidal field on the circularly polarized radiation is detectable using a photoelectric polarimeter.
MDS/MIT high-speed data-acquisition and analysis software system
Authors: Fredian Thomas W. , Stillerman Joshua A.
Published: July 2002

MDS is a high-speed VAX-based CAMAC-oriented data-acquisition and analysis system. It was developed at MIT for use on the ALCATOR C and TARA experiments. MDS consists of a coherent set of general purpose, flexible tools for experimental data handling. Using MDS a scientist can set up a complete diagnostic including CAMAC data acquisition, display, and analysis without writing any code. MDS has been in use at MIT for over two years and is also installed and operational at numerous other labs including PPPL, Oak Ridge National Laboratory, UCLA, and Sandia National Laboratory. The computer equipment on which MDS is installed ranges from large VAXclusters to small stand-alone MicroVAX II systems. The authors of this paper hope to present an overview for those unfamiliar with the MDS system, to discuss planned improvements in the system, and to discuss ideas for future enhancements that may benefit all the MDS sites.
Fast, sensitive laser deflection system suitable for transient plasma analysis
Authors: Enloe C. L. , Gilgenbach R. M. , Meachum J. S.
Published: July 2002

A laser deflection measurement system has been developed which is both fast (τ≊20 ns) and sensitive (δφ≊0.5 μrad). This diagnostic is capable of sensing and discriminating between electrons and neutral particles in a multicomponent plasma, and yields quantitative results. The technique allows continuous measurements in time. Construction is inexpensive and simple to field. This system is, therefore, highly competitive with traditional techniques in diagnosing the development of transient plasmas.
Emittance meter for time-resolved electron-beam propagation studies
Authors: Schneider R. F. , Smith J. R. , Rhee M. J.
Published: July 2002

A simple emittance meter is designed which is capable of measuring the temporal evolution of the emittance of a propagating electron beam. The design is based on that of a slit-pinhole emittance meter. A Cherenkov emitter is utilized as the electron detector. A streak camera is used to record the time-resolved optical Cherenkov radiation from the detector. Experimental results with a 700-keV, 4-kA, 100-ns electron beam are presented.
Time-resolved mass and energy analysis by position-sensitive time-of-flight detection
Authors: Pollard J. E. , Lichtin D. A. , Janson S. W. , Cohen R. B.
Published: July 2002

We describe a new method for time-resolved mass and kinetic energy analysis of ionic or neutral species in the range of 1–150 amu and 0.5–500 eV. Time-of-flight mass spectrometry is combined with position-sensitive detection to measure energy spectra for multiple masses at burst-mode sampling rates as high as 50 kHz. The detector is a rectangular microchannel plate with a 96-element metal anode array that is read out either by fast analog-to-digital converters or by discriminators and scalers. The apparatus is configured so that the measured ion drift time varies as the square root of the mass-to-charge ratio and the displacement along the detector varies as the square root of the energy-to-charge ratio. Applications are envisioned in plasma analysis, in beam-scattering experiments, and in diagnostic measurements for spacecraft propulsion.
Optimized beamline design for macromolecular crystallography at the Cornell High Energy Synchrotron Source (CHESS) (abstract)
Authors: Schildkamp Wilfried , Bilderback Donald , Moffat Keith
Published: July 2002

The A1 station on the CHESS wiggler beamline has been the workhorse for most macromolecular crystallographic experiments. This station is equipped with a fixed energy focusing germanium (111) monochromator and a focusing total reflection mirror. Our macromolecular crystallographers made full use of the high flux of more than 1012 photons/s/mm2 and the stable beam conditions, both in position and energy resolution. As a result, the A1 station was heavily oversubscribed. CHESS is presently expanding its capabilities and a new diffraction station for macromolecular crystallography is under construction. This beamline will be powered by a 24-pole hybrid permanent magnet wiggler with a critical energy of 25 keV. A focusing monochromator, which handles a specific heat load of 10 W/mm2, will have a range of tunability which covers all relevant absorption edges from 7 to 15 keV using a Ge(111) crystal. The energy resolution and the focusing properties remain constant within a factor of 2 over the entire tunability range. We expect a brilliance of about 1013 photons/s/mm2/mrad2/0.1% bandpass. The diffraction station will be equipped with an oscillation camera which can be used with x-ray film of 5×5 or 8×10 in. size or alternatively with Kodak storage phosphors. A wide variety of clamp-on accessories, like crystal coolers, fast shutters, helium pathways, polarimeter, etc. are available. The station will contain a beampipe system, which can also be used for small angle scattering experiments with sample-to-detector distances of up to 3000 mm. The entire diffraction station, its control area, a biological preparation area, and a darkroom are to be embedded in a biological safety containment of the level BL3. This will allow diffraction studies of virulent strains of viruses and other biohazards, which could not previously be studied at synchrotron radiation sources before without causing major disruption to the normal laboratory procedure.
Infrared hot-electron transistor with a narrow bandpass filter for high temperature operation
Authors: Lee C. Y. , Choi K. K. , Leavitt R. P. , Eastman L. F.
Published: July 2002

We have designed and demonstrated a narrow bandpass filter, which is composed of a double-barrier structure, for an infrared hot-electron transistor with a cutoff wavelength at 14 μm. The filter is capable of suppressing the low energy thermally assisted tunneling current as well as the high energy thermionic emission current that are not degenerate with the photoelectrons. As a result, the detector can be operated at 77 K with a 45% BLIP level and an estimated NEΔT of 38 mK.
Methods to measure properties of slow-scan CCD cameras for electron detection
Authors: de Ruijter W. J. , Weiss J. K.
Published: July 2002

New ways to measure detection properties of slow-scan charge-coupled device (CCD) cameras suitable for electron microscopy, mainly based on the statistics of single-electron events, are discussed. The experiments concentrate on the newly introduced Gatan 679 slow-scan CCD camera. It has been established that for this instrument (if equipped with a thin YAG scintillator) 20% of the true intensity is recorded at the highest detectable spatial frequency (Nyquist frequency), limited mostly by the modulation transfer function of the YAG scintillator. The detection quantum efficiency is 0.45 for single 100-kV electrons and 0.15 for single 400-kV electrons, and is approaching unity for intensities higher than ten electrons. Furthermore, nonlinearity of the response is smaller than deviations in the image intensity due to shot noise. Examples are presented illustrating the detection properties of slow-scan CCD cameras for electron imaging, which also include high dynamic range and negligible geometric distortion.
Nanosecond transient absorption spectrophotometer with dye laser probing and computer control
Authors: Jasny Jan , Sepit Jerzy , Karpiuk Jerzy , Gilewski Janusz
Published: July 2002

A computer controlled apparatus for laser flash spectroscopy has been constructed. Nitrogen laser (energy 1 mJ, pulse width 1 ns) is used both for excitation of the sample and for pumping a tunable dye laser which serves as a source of monitoring light. Two different scan modes are possible: (i) a scan with a fixed wavelength of the monitoring light: the temporal evolution of the transient absorption in the range from −2 up to 100 ns can be observed by changing the length of the variable self-compensating optical delay line, or (ii) a scan with a fixed time delay: the corresponding transient absorption in the range 380–800 nm can be measured. For illustration, the transient absorption spectrum of benzophenone in methylcyclohexane, decay curves of the singlet state of benzanthracene in ethanol in the presence of a quencher, and a ‘‘negative absorption’’ of rhodamine B in nitriles are reported.
Solid material evaporation into an electron cyclotron resonance source by laser ablation
Authors: Harkewicz R. , Stacy J. , Greene J. , Pardo R. C.
Published: July 2002

In an effort to explore new methods of producing ion beams from solid materials, a laser-ablation technique for evaporating materials directly into an electron cyclotron resonance (ECR) ion source plasma was developed. A pulsed NdYaG laser with approximately 25 W average power and peak power density on the order of 107 W/cm2 has been used off-line to measure ablation rates of various materials as a function of peak laser power. The benefits anticipated from the successful demonstration of this technique include the ability to use very small quantities of materials efficiently, improved material efficiency of incorporation into the ECR plasma, and decoupling of the material evaporation process from the ECR source tuning operation. The results of these tests are reported herein and the design is described for incorporating such a system directly with the Argonne Tandem Linac Accelerator System Positive Ion Injector ECR (ATLAS PII-ECR) ion source.
First experimental results from IBM/TENN/TULANE/LLNL/LBL undulator beamline at the advanced light source
Authors: Jia J. J. , Callcott T. A. , Yurkas J. , Ellis A. W. , Himpsel F. J. , Samant M. G. , Stöhr J. , Ederer D. L. , Carlisle J. A. , Hudson E. A. , Terminello L. J. , Shuh D. K. , Perera R. C. C.
Published: July 2002

The IBM/TENN/TULANE/LLNL/LBL Beamline 8.0 at the advanced light source combining a 5.0 cm, 89 period undulator with a high-throughput, high-resolution spherical grating monochromator, provides a powerful excitation source over a spectral range of 70–1200 eV for surface physics and material science research. The beamline progress and the first experimental results obtained with a fluorescence end station on graphite and titanium oxides are presented here. The dispersive features in K emission spectra of graphite excited near threshold, and found a clear relationship between them and graphite band structure are observed. The monochromator is operated at a resolving power of roughly 2000, while the spectrometer has a resolving power of 400 for these fluorescence experiments.