bluuebunny/crossref_metadata_2025 huggingface dataset:
Can Turn around Time Compliance in Hospital Laboratories be Set to Auto Pilot Mode? – A 2 Years’ Experience
Authors: Yadav Charu , Saxena Renu , Kamini V. , Harith Arun Kumar
Published: September 2022

Background: A short Turn Around Time (TAT) is unanimously desired and equated to efficiency of a hospital laboratory. Despite automation, laboratories often find it difficult to meet the TAT demands. The major lacuna noticed was that our technicians did not know exactly when a sample was likely to exceed the TAT limit.

Methods: This prospective study was done to develop display screens giving real time information to the working staff and to assess their impact on the TAT compliance. Real time information on daily TAT status, color coded list of pending samples and technician’s daily performance were displayed as screens and graphs using aspx/PHP script and data extracted from hospital database. The TAT outliers data was then compared before, during and after the study.

Results: The project was initiated in November 2017 and the modules were implemented by December 2018. The TAT compliance of urgent samples significantly improved from 80-85% in Oct-Dec 2017 to 90-95% in Jan-Mar 2018. After the implementation of the screens, more than 90% of urgent and routine samples were released within 105 and 180 minutes of receiving respectively. The corresponding figures before this study were > 120 minutes and 300 minutes for urgent and routine samples respectively.

Conclusion: By providing the staff actionable information, on a real time basis, we were able to achieve a high TAT compliance. As this was achieved by only displaying relevant information and not by policing, judicious use of technology can help laboratories achieve TAT targets on an auto-pilot mode.
Glutathione an Effective Adjuvant Therapy for Acute Respiratory Distress Syndrome Associated with COVID-19 Infection
Authors: Dewan Bhupesh , Shinde Siddheshwar
Published: September 2022

Aim: This study is aimed at evaluating the efficacy and safety of Intravenous Glutathione in moderate COVID-19 patients with respiratory distress.

Study Design: A randomized, multicentric, double-blind, placebo-controlled, comparative Phase III clinical trial.

Place and Duration of Study: This clinical trial was conducted at 7 geographically distributed sites across India between February 2021 to September 2021.

Participants: The study enrolled 240 participants who were tested and confirmed cases of moderate COVID-19 with respiratory distress.

Interventions: Intravenous glutathione (GSH) at a loading dose of 2400 mg on the first day, followed by a dose of 1200 mg every 12 hours for seven days.

Methodology: Patients were randomized into two groups in a ratio of 1:1, to receive either glutathione or placebo. Both the study drugs were given as an addition to the standard of care (SOC). The study site staff, investigator and patients were blinded to the treatment allocation. The primary endpoint of the study was two or more points of improvement on the WHO 7-point ordinal scale whereas the secondary endpoints were the proportion of patients not requiring oxygen supplementation after treatment. Other secondary endpoints included the proportion of patients who changed from a higher to a lower score on the WHO 7-Point ordinal scale, the proportion of patients remaining hospitalized, the need of non-invasive ventilation or new requirement of high flow oxygen use, and incidences of adverse events.

Results: A significant clinical improvement in the GSH group (p<0.001) was observed in early treatment days. On day 3, GSH group had improvement in 49.15% of the patients as compared to 31.96% on placebo (p=0.007; odds ratio, 2.06; 95% CI, 1.22-3.48). A higher proportion of patients with baseline score of 5 or more in the GSH group (64.63%) showed improvement as compared to the placebo (46.58%) (p=0.024; odds ratio, 2.10; 95% CI, 1.10-4.00). A higher proportion of patients in the GSH group attained a score of 3 or less signifying no need of Oxygen supplementation, as compared to the placebo group on Day 2, Day 3 and Day 4. A reduction of severity in clinical status was also observed on Day 3, Day 4 and Day 5. The risk of remaining in the hospital was reduced by 37% in the GSH group. The 7-day dose of GSH was well tolerated by the patients.

Conclusion: GSH supplementation reduces the cytokine storm and respiratory distress in patients with COVID-19 pneumonia. GSH can also be used for treating respiratory distress due to other etiologies due to its favorable safety profile. GSH treatment should also be explored in a larger number of patients with ARDS of varied etiologies in randomized trials.
Anti-myocardial Infarctus, Efficient Antipoison and Anti-prostate Mighty Spicy Miscellany
Authors: Kunyima A. B. , Kunyima P. D. M. D. , Kuburhanwa J. C. , Kunyima M. B.
Published: September 2022

Background: Cardiovascular diseases, cancers and diabetes that are the main cause of mortality in the world have as principal origine the lack of food (life) hygiene and environmental pollution at which it should be added the synthesis chemical products and the poisons playing a prominent and active role in this human drama. In this paper it is shown that with spicy blend rationally performed on the basis of their natural properties, prostate and myocardial infarction can be healed. Also this mixture can treat some poisons when detected before.

Aim and Objective: The laboratory of physical organic chemistry, food and physical cardiochemistry, Lacopa-CCP in acronym, has just developed a powerful blend of spices based on Turmeric called PdeluxeKK (Paulin Deluxe KUNYIMA KUNYIMA), conceived at the beginning to treat a myocardial infarction caused by poisoning clinically established and after become unexpectedly efficient in the treatment of a prostate and other poisons.

Methodology: This mixture contains in order turmeric in large quantity, ginger, black pepper, garlic and red onion, original pure honey and the variant of PdeluxeKK incorporates at the end before the honey the red beetroot to make this mixture more reliable against cyanide poisons through its betacyanin and to prevent eventual anemic problems during the treatment. The order of the mixture is of great importance because it has been observed that its effectiveness changes not only with the proportions of the components involved but also according to the order of addition of the components which constitute this mixture. The mixture pastry should be kept between - 5°C and 0°C.

Results: Prostate and myocardial infarction clinically established have been satisfactorily treated by PdeluxeKK. Also many poisons detected in human body are successfully treated by PdeluxeKK.

Conclusion: This mighty spicy miscellany successfully treats prostate, myocardial infarction and certain poisons.
Mobile applications to face tuberculosis: a technological prospect / Aplicativos móveis para enfrentamento da tuberculose: uma prospecção tecnológica
Authors: Mendes Mariana , Silveira Bordignon Juliana , Coelho Bruna , Franciely Daiana Engel Franciely , Solange Vieira Tourinho Francis
Published: September 2022

Objetivo: identificar aplicativos móveis disponíveis para monitoramento da tuberculose e suas contribuições para o seu enfrentamento. Método: prospecção diagnóstica, realizada com busca nas plataformas App Store® e Google Play Store®. A coleta de dados ocorreu em abril de 2021, utilizando os termos “Tuberculose”, “Tuberculosis” e “Tuberculosis”, em português, espanhol e inglês. A extração, organização e tabulação dos dados foi por meio da ferramenta Microsoft Excel® 2016.  Resultados: a busca resultou em 24 aplicativos na App Store® e 510 na Google Play Store®. Após aplicação dos critérios de inclusão e exclusão, 42 aplicativos foram analisados e categorizados em aplicativos voltados ao público geral e aplicativos voltados para informações aos profissionais de saúde. Conclusão: a prospecção possibilitou conhecer o estado da arte dos aplicativos para tuberculose, identificando-se a importância da interatividade das interfaces, dos recursos de lembretes para uso adequado das medicações e dos espaços para dúvidas frequentes e troca de experiências.
Partial restoration of inactivated ribosomes with sodium borohydride or amino acids
Authors: Li Qing , Ling Jin , Liu Wang-yi
Published: July 2002

The aldehyde radical of ribose C′1 at position 4324 in rat liver 28S rRNA generated by RNA N‐glycosidase was either reduced to an hydroxyl group by sodium borohydride or converted into aldimine through a nucleophilic addition of amino acid used as a primary amine. Analysis of the R‐fragment of 28S rRNA by polyacrylamide gel electrophoresis showed that the reduction of aldehyde to an hydroxyl group with sodium borohydride was highly specific. The protein synthesis activity of modified ribosomes was partially restored with the removal of the active aldehyde by sodium borohydride or amino acid. Reduction of aldehyde with sodium borohydride restored 43.1 % of the protein synthesis activity. Among the twenty natural amino acids tested, tryptophan and histidine could restore 57.4% and 42.1 % of the ribosome activity when brome mosaic virus RNA was used as mRNA. We came to the conclusion that the active aldehyde radical at position 4324 of 28S rRNA in modified ribosome may cause the inactivation of the ribosome for protein synthesis.
Changes in mitochondrial membrane potential during staurosporine‐induced apoptosis in Jurkat cells
Authors: Scarlett Jared L. , Sheard Philip W. , Hughes Gillian , Ledgerwood Elizabeth C. , Ku Hung-Hai , Murphy Michael P.
Published: July 2002

Cytochromecrelease from mitochondria is central to apoptosis, but the events leading up to it are disputed. The mitochondrial membrane potential has been reported to decrease, increase or remain unchanged during cytochromecrelease. We measured mitochondrial membrane potential in Jurkat cells undergoing apoptosis by the uptake of the radiolabelled lipophilic cation TPMP, enabling small changes in potential to be determined. The ATP/ADP ratio, mitochondrial and cell volumes, plasma membrane potential and the mitochondrial membrane potential in permeabilised cells were also measured. Before cytochromecrelease the mitochondrial membrane potential increased, followed by a decrease in potential associated with mitochondrial swelling and the release of cytochromecand DDP‐1, an intermembrane space house keeping protein. Mitochondrial swelling and cytochromecrelease were both blocked by bongkrekic acid, an inhibitor of the permeability transition. We conclude that during apoptosis mitochondria undergo an initial priming phase associated with hyperpolarisation which leads to an effector phase, during which mitochondria swell and release cytochromec.
Mother Jones
Authors: Filbeck Greg
Published: July 2002

In this paper, we examine the returns to a portfolio of 12 publicly held firms that were featured in the July/August 1997 edition of Mother Jones as the “20 Better Places to Work” (the remaining eight are privately held). This survey was based on the firm's track record for charitable giving, fair labor practices, progressive benefits, sound environmental practices, and satisfied employees. While there is much evidence that the above qualities are very desirable for employees, little evidence exists indicating whether such a record results in increased shareholder wealth. In this study, we compare the annual returns, on a raw and risk‐adjusted basis, for the selected firms to a broad market index, as well as a more appropriate benchmark (based on market capitalization and industry classification). We also determine whether there is an announcement effect associated with the public release of the list of Mother Jones firms.
Classic specific immunotherapy and new perspectives in specific immunotherapy for food allergy
Authors: Burks Wesley , Bannon Gary , Lehrer Samuel B.
Published: July 2002

Food allergy is a major cause of life‐threatening hypersensitivity reactions. Food‐induced anaphylaxis is the most common reason for someone to present to the emergency department for an anaphylactic reaction. The avoidance of the allergenic food is the only method of preventing further reactions that is currently available for sensitized patients. Strict avoidance of specific foods is the accepted treatment of food‐induced allergic reactions but is often an unrealistic therapeutic option for food‐induced hypersensitivity reactions for the many reasons previously described. Desirable therapeutic strategies for the treatment and prevention of food allergies must be safe, relatively inexpensive and easily administered. Recent advances in the understanding of the immunological mechanisms underlying allergic disease and better characterization of food allergens have greatly expanded the potential therapeutic options for future use. Several different forms of immunomodulatory therapies are currently under investigation: peptide immunotherapy, mutated protein immunotherapy, allergen DNA immunization, vaccination with immunostimulatory DNA sequences and anti‐immunoglobulin E (Anti‐IgE) therapy.
Mapping of a spectrin-binding domain of human erythrocyte membrane protein 4.2
Authors: MANDAL Debabrata , MOITRA Prasun K. , BASU Joyoti
Published: July 2002

Protein 4.2 is a major component of the red blood cell membrane skeleton. Deficiency of protein 4.2 is linked with a variety of hereditary haemolytic anaemias. However, the interactions of protein 4.2 with other proteins of the erythrocyte membrane remain poorly understood. The major membrane-binding site for protein 4.2 resides on the cytoplasmic domain of band 3. Protein 4.2 interacts directly with spectrin in solution, suggesting that it stabilizes interactions between the membrane skeleton and the erythrocyte membrane. A 30kDa polypeptide, with its N-terminus corresponding to amino acid residue 269, derived by partial proteolysis of protein 4.2, was found to interact with biotinylated spectrin in gel renaturation assays. A series of overlapping glutathione S-transferase fusion peptides were constructed, and an α-helical domain encompassing residues 470–492 was found to be instrumental in mediating protein 4.2—spectrin interactions. Direct binding of a synthetic peptide, with the sequence corresponding to residues 470–492, to spectrin and the ability of the peptide to inhibit spectrin binding of protein 4.2 confirmed that these residues are crucial in mediating protein 4.2—spectrin interactions.
Phospholipase D1 is threonine-phosphorylated in human-airway epithelial cells stimulated by sphingosine-1-phosphate by a mechanism involving Src tyrosine kinase and protein kinase Cδ
Authors: GHELLI Anna , PORCELLI Anna M. , FACCHINI Annalisa , HRELIA Silvana , FLAMIGNI Flavio , RUGOLO Michela
Published: July 2002

The regulatory role of protein kinase C (PKC) δ isoform in the stimulation of phospholipase D (PLD) by sphingosine-1-phosphate (SPP) in a human-airway epithelial cell line (CFNPE9o−) was revealed by using antisense oligodeoxynucleotide to PKCδ, in combination with the specific inhibitor rottlerin. Cell treatment with antisense oligodeoxynucleotide, but not with sense oligodeoxynucleotide, completely eliminated PKCδ expression and resulted in the strong inhibition of SPP-stimulated phosphatidic acid formation. Indeed, among the PKCα, β, δ, ∊ and ζ isoforms expressed in these cells, only PKCδ was activated on cell stimulation with SPP, as indicated by translocation into the membrane fraction. Furthermore, pertussis toxin and genistein eliminated both PKCδ translocation and PLD activation. In particular, a significant reduction in phosphatidylbutanol formation by SPP was observed in the presence of 4-amino-5-(4-methylphenyl)-7-(t-butyl) pyrazolo [3,4-d] pyrimidine (PP1), an inhibitor of Src tyrosine kinase. Furthermore, the activity of Src kinase was slightly increased by SPP and inhibited by PP1. However, the level of PKCδ tyrosine phosphorylation was not increased in SPP-stimulated cells, suggesting that Src did not directly phosphorylate PKCδ. Finally, the level of serine phosphorylation of PLD1 and PLD2 isoforms was not changed, whereas the PLD1 isoform alone was threonine-phosphorylated in SPP-treated cells. PLD1 threonine phosphorylation was strongly inhibited by rottlerin, by anti-PKCδ oligodeoxynucleotide and by PP1. In conclusion, in CFNPE9o− cells, SPP interacts with a membrane receptor linked to a Gi type of G-protein, leading to activation of PLD, probably the PLD1 isoform, by a signalling pathway involving Src and PKCδ.
Down-regulation of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene by insulin: the role of the forkhead transcription factor FKHRL1
Authors: NADAL Alícia , MARRERO Pedro F. , HARO Diego
Published: July 2002

Normal physiological responses to carbohydrate shortages cause the liver to increase the production of ketone bodies from the acetyl-CoA generated from fatty acid oxidation. This allows the use of ketone bodies for energy, thereby preserving the limited glucose for use by the brain. This adaptative response is switched off by insulin rapidly inhibiting the expression of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase (HMGCS2) gene, which is a key control site of ketogenesis. We decided to investigate the molecular mechanism of this inhibition. In the present study, we show that FKHRL1, a member of the forkhead in rhabdosarcoma (FKHR) subclass of the Fox family of transcription factors, stimulates transcription from transfected 3-hydroxy-3-methylglutaryl-CoA synthase promoter-luciferase reporter constructs, and that this stimulation is repressed by insulin. An FKHRL1-responsive sequence AAAAATA, located 211bp upstream of the HMGCS2 gene transcription start site, was identified by deletion analysis. It binds FKHRL1 in vivo and in vitro and confers FKHRL1 responsiveness on homologous and heterologous promoters. If it is mutated, it partially blocks the effect of insulin in HepG2 cells, both in the absence and presence of overexpressed FKHRL1. These results suggest that FKHRL1 contributes to the regulation of HMGCS2 gene expression by insulin.
Population pharmacokinetics of carbamazepine in Singapore epileptic patients
Authors: Chan Eli , Lee How Sung , Hue Swee Shan
Published: July 2002

Aims  To document the population pharmacokinetics of carbamazepine in patients with epilepsy living in Singapore, the majority of whom are of Chinese origin and others of minority races.

Methods  Steady‐state plasma carbamazepine concentration data were gathered during routine care from various hospitals in Singapore for patients with epilepsy. Age, body weight, gender, race, formulation and concurrent medication (for other illnesses) were the fixed effects (covariates) tested simultaneously for their influence on the population mean of carbamazepine clearance, using the nonlinear mixed‐effects model, in the NONMEM program.

Results  No age, gender, race, or formulation–related effect was found. Body weight (W), age (A) and concurrent medication with phenobarbitone (PB) emerged as the determinants of carbamazepine clearance (CL). The final regression model for carbamazepine clearance found best to describe the data was CL = 40.7 × A0.494 × W−1.17 × 1.44PB where CL is in l day−1 kg−1, A is in years, W is in kg and PB = 0 for a patient on carbamazepine only and PB = 1 for a patient on concomitant PB. The corresponding interindividual variability (CV%) in CL, described by using an exponential model, was 21.4%, and the residual error, described by using an exponential error model, was 18.2%. Predictive performance of this population covariate model was evaluated by Bayesian forecasting in a similar, but independent cohort of patients. There was no statistically significant bias between predicted and measured plasma carbamazepine concentrations. The population mean value of carbamazepine clearance obtained was similar to that previously reported for patients with a very different ethnic (Caucasians and Blacks) or geographical background (South Africa, Europe and USA).

Conclusions  The derived covariate regression model reasonably predicted concentrations in the separate validation Singapore patient data set. The correlation between carbamazepine clearance and patient‐specific characteristics may thus allow dosage adjustment to be made to achieve target steady‐state plasma concentrations.
Activity patterns and oviposition rates of Aphytis lingnanensis females, a parasitoid of California red scale Aonidiella aurantii: implications for successful biological control
Authors: Fernando L. C. P. , Walter G. H.
Published: July 2002

1. Activity patterns of Aphytis lingnanensis Compere (Hymenoptera: Aphelinidae) females were determined. Females have a preovipositional period of 2–6.5 h and oviposit daily until they die. The average lifetime fecundity was 191 eggs (n = 10 females), with a maximum of 13 eggs per day, but usually far fewer. Females do not lay eggs at night as low light levels reduce the propensity to oviposit.

2. Aphytis lingnanensis females showed a repeatable pattern of activity during the course of the day, ovipositing actively during the first 1.5 h of their 7 h exposure to hosts. Thereafter, activity levels decreased sharply and females spent relatively long intervals resting. Activity occurred in fairly discrete bouts, with long periods of inactivity, ranging from 12 to 231 min between bouts.

3. Each day, females laid most eggs during their first bout of oviposition, with availability of mature eggs in the ovaries dictating the duration and intensity of ovipositional bouts. Once females completed a bout of oviposition in the laboratory, they moved away from the hosts even though many suitable hosts remained. They stood immobile, sheltering, until they matured more eggs.

4. These results suggest how general biological control models and dynamic state variable models of behaviour can be made more realistic. In particular, the behaviour of females does not remain constant over extended periods, particularly because of egg depletion, which suggests that the interaction between the ovipositional history of the individual and its physiological capabilities dictates the response of females to particular circumstances, and thus contributes to patterns of parasitism in the field.

5. It is predicted that A. lingnanensis females in the field are inactive at night and begin ovipositing when it becomes light enough in the morning. Egg depletion is likely if enough hosts are available, but should occur later in the day than was recorded in the laboratory. Egg‐depleted females are likely to shelter while they mature more eggs, but may undertake interpatch movement.
Patch departure mechanisms and optimal host exploitation in an insect parasitoid
Authors: Driessen Gerard , Bernstein Carlos
Published: July 2002

1. Patch‐leaving decisions are of utmost importance in determining parasitoid foraging success. Parasitoids are known to use both marks left by hosts (chemical or otherwise) and ovipositions to assess host availability and to decide when to leave a host patch.

2. Previous studies have shown that, depending on the species, ovipositions either increase (an incremental mechanism) or decrease (a decremental mechanism) the patch residence times of parasitoids. Reports in the literature conflict on which mechanism is used by Venturia canescens, a parasitoid of pyralid moth larvae.

3. We hypothesize that, as a consequence of saturation in the capacity of the parasitoid to discriminate between host densities at high host numbers, V. canescens uses a decremental mechanism at low host numbers and an incremental one at high host numbers. We call this a ‘switching mechanism’.

4. Our experiments show that even if discrimination capacity saturates, V. canescens uses a decremental mechanism over a wide range of host densities.

5. The distribution of hosts in different fruits species under field conditions suggests a switching mechanism would not evolve in natural situations.

6. A model of patch departure in V. canescens is constructed and tested using an independent set of experiments. The model suggests that the patch leaving mechanism in V. canescens is a stochastic decremental one. As might be expected from Weber's Law, the initial leaving tendency is a convex decreasing function of kairomone concentration. The leaving tendency increases exponentially with the time spent in the patch without ovipositing. Ovipositions cause a sudden increase in leaving tendency.

7. Simulations suggest that a decremental mechanism would be out‐competed by either one indifferent to ovipositions or an incremental one, only when travel times are much larger than those that are likely to occur in the field.
The Washington State Intergenerational Study of Birth Outcomes: methodology and some comparisons of maternal birthweight and infant birthweight and gestation in four ethnic groups
Authors: Emanuel  , Leisenring  , Williams  , Kimpo  , Estee  , O’Brien  , Hale
Published: July 2002

A statewide database of vital records and hospital discharge summaries of obstetric and neonatal admissions for Washington State in 1987–95 was linked to the birth certificates of mothers born in the state. A total of 46 000 births to mothers of four racial/ethnic groups were studied: Whites, African‐Americans, Native Americans and Hispanics. For all four groups inverse associations were found between maternal birthweight and infant low birthweight and preterm birth. The birthweight distribution of African‐American mothers was displaced markedly downwards compared with the Whites; this difference in maternal birthweight is offered as a partial explanation of the greater prevalence of suboptimal pregnancy outcomes in the former. In contrast, the maternal birthweight distributions of Whites, Native Americans and Hispanics are similar; differences in pregnancy outcomes are probably more related to maternal preconceptional and postnatal factors in these groups as well as differences in pregnancy‐related factors. Mothers’ birthweight may have clinical value in identifying high‐risk pregnancies.
Ring keratitis from topical anaesthetic misuse
Authors: Frcophth S K Webber , Fraco G L Sutton , Fraco M A Lawless , Fraco C M Rogers
Published: July 2002

Background: Topical anaesthetic abuse is now an established differential diagnosis of ring keratitis. Published evidence suggests that this condition often has a poor prognosis, with the eyes sometimes requiring penetrating keratoplasty or the patient becoming blind.

Method: A case of topical anaesthetic abuse and its subsequent management is presented. Ocular examination including pachymetry and specular microscopy is reported.

Results: The cornea made an excellent recovery, allowing a visual acuity of 6/6. Pachymetry showed corneal thickening and specular microscopy demonstrated a decreased cell count in the affected eye.

Conclusions: With prompt recognition and appropriate treatment the prognosis for these cases can be excellent. However, there is evidence to suggest permanent cellular damage to the endothelium.
Effect of substrate temperature on migration of Si in planar-doped GaAs
Authors: Santos M. , Sajoto T. , Zrenner A. , Shayegan M.
Published: July 2002

Quantum oscillations in the magnetoresistance of GaAs δ (or planar) doped with Si are analyzed to obtain the electron densities of the electric subbands. We compare these densities with the results of self-consistently calculated subband structures of δ-doped GaAs in which the spread of the dopant atoms (Si) in the growth direction is a fitting parameter. The results indicate that there is negligible spread in structures grown at a substrate temperature TS ≲530 °C, while in structures grown at higher TS there is measurable spread which increases with TS. For TS =640 °C, the Si spread is determined to be ≂220 Å. An examination of the three-dimensional Si densities in these layers indicates that the dominant mechanism for the spreading of Si for TS >600 °C is the migration of Si to satisfy the solid solubility limit.
Femtosecond all-optical switching in AlGaAs waveguides using a time division interferometer
Authors: LaGasse M. J. , Anderson K. K. , Haus H. A. , Fujimoto J. G.
Published: July 2002

All-optical switching of femtosecond pulses in AlGaAs waveguides is investigated using a novel time division interferometric technique which eliminates thermal imbalances. In addition to an instantaneous refractive index nonlinearity, free-carrier generation via two-photon absorption produces a response of several hundred picoseconds duration.
Mechanism for diamond growth from methyl radicals
Authors: Harris Stephen J.
Published: July 2002

We use a 9-carbon model compound to describe a proposed mechanism for homoepitaxial growth of diamond from methyl radicals on a hydrogenated, electrically neutral (100) surface. We estimate enthalpy and entropy changes for each step in the mechanism using group additivity methods, taking into account the types of bonding and steric repulsions found on the (100) surface. Rate constants are estimated based on analogous reactions for hydrocarbon molecules, while gas phase species concentrations are taken from our previous measurements. The rate equations are then integrated. The method, which contains no adjustable parameters or phenomenological constants, predicts a growth rate of between 0.06 and 0.6 μm/h, depending on the local details of the surface. Uncertainties related to the use of a model compound rather than diamond are discussed. The analysis demonstrates that the proposed mechanism is feasible.
Simple reflection technique for measuring the electro-optic coefficient of poled polymers
Authors: Teng C. C. , Man H. T.
Published: July 2002

A simple reflection technique for measuring the electro-optic coefficient of nonlinear optical polymeric films is described. The technique is based on the polarization rotation of a laser beam due to the electro-optic effect. It requires no waveguiding and can be used to measure polymeric films during, as well as after, the electrical poling process. The results are in excellent agreement with those obtained from the more conventional but much more time consuming waveguiding method.
Tunneling resonance studies of electronic ministop gap mode in coupled semi-infinite semiconductor superlattices
Authors: Huang F. Y.
Published: July 2002

A numerical technique is developed to analyze the electronic state in coupled semi-infinite semiconductor superlattices. It is found that the superlattice miniband shrinks to discrete energy levels near the surface, and localized electronic surface states with energy falling within the ministop gap exist under certain conditions. Numerical calculations are also compared with results from an exact eigenvalue equation.
Evidence for a new passivating indium rich phosphate prepared by ultraviolet/ozone oxidation of InP
Authors: Hollinger G. , Gallet D. , Gendry M. , Besland M. P. , Joseph J.
Published: July 2002

Using x-ray photoelectron spectroscopy (XPS), it is demonstrated that noncrystalline thin oxide layers grown on InP by ultraviolet (UV)/ozone oxidation are composed of a single phase of phosphate average composition InP0.5O2.75 which do not exist as crystalline compounds. The ability of nonstoichiometric InP native oxides to passivate InP surfaces is discussed on the basis of these new findings.
Photoreflectance study of photovoltage effects in GaAs diode structures
Authors: Airaksinen V. M. , Lipsanen H. K.
Published: July 2002

Photoreflectance measurements of a GaAs p-i-n diode as a function of temperature (50–450 K) are reported. The photovoltage in the structure is obtained from the electric field strength which is determined from the Franz–Keldysh oscillations in the photoreflectance spectrum. The results are compared to those from an n-GaAs structure where the Fermi level is pinned at the surface. In this case the photovoltage can be determined only by fixing the energy of the Fermi pinning level. The theoretical photovoltages are also calculated from the ideal p-n and Schottky diode equations. This study clearly shows the importance of the photovoltage effects in the photoreflectance measurements.
Novel calixarenes in thin films for efficient second harmonic generation
Authors: Heesink G. J. T. , van Hulst N. F. , Bölger B. , Kelderman E. , Engbersen J. F. J. , Verboom W. , Reinhoudt D. N.
Published: July 2002

Calix[4]arenes are a novel type of molecules for nonlinear optics. In a single molecule four π-conjugated systems are combined. Corona poled guest-host polymer systems [calix[4]arenes-poly(methyl-methacrylate)] with transparency into the UV and loading up to 100% show a high degree of orientation. The maximum resonant d33 nonlinear coefficient measured at a fundamental wavelength of 590 nm is 51 pm/V. The d33 values of the thin films relax after poling to 65% of their maximum value. Results indicate self-organization of the molecules upon poling.
Emission of GHz shear waves by ferroelastic domain walls in ferroelectrics
Authors: Arlt G. , Böttger U. , Witte S.
Published: July 2002

The 90° domain walls and comparable ferroelectric domain walls are strong sound emitters in the GHz range. The elastic medium on both sides of the domain wall with its mass and elastic properties is a quasi-infinite transmission line into which the sound is emitted. This emission causes a strong dielectric dispersion at GHz frequencies and may form the basis for many dispersive effects in this frequency range which were observed during the last 40 years in many ferroelectric and even some magnetic materials. A simple elastic-electric equivalent circuit describes the mechanism of sound emission.
Mapping of mobile charges on insulator surfaces with the electrostatic force microscope
Authors: Domanský K. , Leng Y. , Williams C. C. , Janata J. , Petelenz D.
Published: July 2002

Migration of surface ions in lateral fields on insulator surfaces may modify the electrical characteristics of underlying semiconductor structures causing device instabilities. A high sensitivity electrostatic force microscope is used to image the movement and spatial distribution of surface ions on Si3N4. Mobile surface ions are distributed by the fringing fields of a p-n junction and an open-gate field-effect transistor. The surface charge distribution and topography are imaged simultaneously on a micrometer scale.
U4+:SrF2 efficient saturable absorber Q switch for the 1.54 μm erbium:glass laser
Authors: Stultz Robert D. , Camargo Marly B. , Montgomery Suzanne T. , Birnbaum Milton , Spariosu Kalin
Published: July 2002

Saturable absorber Q switching of the Er:glass laser at 1533 nm using U4+:SrF2 has been obtained. Q-switched pulses of 3 mJ and 60 ns full width at half-maximum were achieved using a 2.69-mm-thick Q switch in a 14-cm-long plane-parallel cavity, with a 3×50 mm Kigre QE-7S Er:glass rod. The high absorption cross section of U4+:SrF2 resulted in efficient Q-switched operation (without intracavity focusing) in agreement with the theoretical predictions.
Crystallization of sol-gel deposited potassium-tantalate-niobate thin films on platinum
Authors: Nazeri Azar
Published: July 2002

Potassium tantalate niobate (KTN) ferroelectric thin films prepared by sol-gel processing have been heat treated in conventional furnaces and through rapid thermal annealing (RTA) to investigate crystallization of the films. Various key factors such as time and temperature influencing the crystallization have been identified. A post-deposition RTA at 750 °C in nitrogen for 5 min crystallized the KTN films into pure perovskite while it took two hours to completely crystallize a similar KTN film in conventional ovens. The effect of preheat treatment at lower temperatures, solution chemistry, and the thickness have also been studied. Preliminary ferroelectric properties of some samples are also presented.
Hydrogen annealed silicon-on-insulator
Authors: Sato Nobuhiko , Yonehara Takao
Published: July 2002

Hydrogen annealing effects on silicon-on-insulator (SOI) materials are reported. High boron concentration of ∼2×1018/cm3 in 0.1-μm-thick SOI layer produced by bond and etch-back SOI (BESOI) method is reduced to ∼ 5×1015/cm3 by annealing at 1150 °C for 1 h. The BESOI surface became very smooth comparable to commercially available polished wafer simultaneously. Separation-by-implantation-of-oxygen wafer was also smoothed by the hydrogen anneal. This is due to surface migration of Si atoms driven by surface energy minimization after removing native oxide.
Infrared measurements in annealed molecular beam epitaxy GaAs grown at low temperature
Authors: Hozhabri N. , Lee S.-H. , Alavi K.
Published: July 2002

We have utilized an infrared absorption technique to study deep level defects in molecular beam epitaxy GaAs grown at 250 °C. From an observed broad absorption band below the conduction edge, the concentration of defects is estimated to be ≊5×1019 cm−3 in an as-grown sample. The concentration of defects decreases exponentially by one order of magnitude due to annealing of the sample at temperatures of 400–500 °C. From the temperature dependence of the defect concentration, the migration energy of defects is calculated to be 0.52±0.02 eV. The measured migration energy shows that part of the defects are arsenic interstitials.
Resonant diagnostics of laser-produced Ba plasmas
Authors: Mostovych A. N. , Ripin B. H. , Stamper J. A.
Published: July 2002

Resonant laser probing diagnostics are used to observe laser-produced barium plasmas (n≤1015 cm−3, T≂1 eV) streaming (v≂106 cm/s) across a strong transverse magnetic field (10 kG). The interaction of the plasma with the magnetic field produces structure in the plasma. The observation of this structure requires resonant diagnostics because of the very low plasma density in this experiment. A YAG-pumped dye laser is tuned near the Ba ii 4554-Å transition for resonant absorption, shadowgraphy, and scattering measurements. Resonant absorption and shadowgraphy images reveal that the plasma expands across the field with virtually no inhibition from the field, while narrowing in the plane perpendicular to the field. In the plane of the magnetic field the expansion is highly structured, taking the form of very narrow jets aligned along the field lines. This structure appears to be a manifestation of a beam-plasma-type instability. For a comparison with theoretical predictions the plasma density and scale lengths are measured by resonant scattering.
A 19-channel fast grating polychromator for ECE measurements in the MTX tokamak
Authors: Guharay S. K. , Boyd D. A. , Ellis R. F. , Stauffer F. J. , Lasnier C. J.
Published: July 2002

A 19-channel grating polychromator is developed to measure the temporal evolution of the electron cyclotron emission spectrum in the second and third harmonics in MTX tokamak with an aim to determine the electron temperature in ohmically heated thermal plasmas as well as the electron energy distribution function in gyrotron and free-electron laser-pumped nonthermal plasmas. The spectrometer can cover a spectral range of about 0.3 to 1.4 mm and deliver a maximum spatial resolution of about 1 cm radially. A combination of a 90° off-axis paraboloidal mirror as the collimating element and a toroidal mirror to focus the diffracted beam yields images on the exit slits with a modest astigmatic distortion. Liquid-helium-cooled InSb detectors are installed in nine channels and associated electronics are optimized for a very low noise and fast response time ( ∼ 2 μs). A faster detector element, with response < 100 ns, is envisioned for the remaining ten channels.
Commercial carbon composition resistors as dynamic stress gauges in difficult environments
Authors: Ginsberg Michael J. , Asay Blaine W
Published: July 2002

Commercial carbon composition resistors have been used as gauges to make dynamic stress measurements in homogeneous and heterogeneous reactive and inert materials. Initial loading was provided by plane wave lenses or shaped charge jets. A series of gas gun and aquarium experiments has been conducted to characterize the behavior of the gauges. Calibrations up to about 14 GPa for nominal 470 Ω resistors and 17 GPa for nominal 4700 Ω resistors are presented. The accuracy of the carbon resistor gauges is limited by response time considerations when submicrosecond rise times are encountered, and there is hysteresis during release. The gauge-to-gauge reproducibility appears to be adequate, and they survive in situations where no other stress transducer has been successfully used, such as in reacting beds of large-particle gun propellants.
Measurement of ion flows using an ‘‘unmagnetized’’ Mach probe in the interchangeable module stellarator
Authors: Peterson B. J. , Talmadge J. N. , Anderson D. T. , Anderson F. S. B. , Shohet J. L.
Published: July 2002

A Mach probe is used to measure poloidal and toroidal flows induced by a biased electrode in IMS. Mach probe theories are reviewed and classified as either magnetized or unmagnetized. A simple geometric model of the IMS Mach probe shows that the variation of the effective probe area as a function of the probe orientation with respect to the magnetic field is 20%–25%, predicting the probe to be only slightly magnetized. Measurements of the variation in the total ion saturation current collected by the probe, as the angle with respect to the magnetic field is varied, demonstrate this level of magnetization only at low neutral pressure at large minor radius, while in other cases the variation in the total collected current is negligible. Based on this result an unmagnetized model [M. Hudis and L. M. Lidsky, J. Appl. Phys. 41, 5011 (1970)] is chosen to analyze the IMS Mach probe data. Comparison of Mach probe poloidal flow measurements as a function of minor radius to calculations of the E×B drift velocity and the ion diamagnetic drift velocity from radial profiles of floating potential and ion saturation current, respectively, shows agreement to within 15%.
Nucleation and growth of diamond films on aluminum nitride coated nickel
Authors: Godbole V. P. , Jagannadham K. , Narayan J.
Published: July 2002

We have studied nucleation and growth characteristics of diamond on nickel with AlN buffer layers. The diamond deposits on partially filled 3-d shell transition metals such as Ni, Fe, and Co usually result in the formation of interposing graphite layers which cause poor adhesion of diamond overlayers. To minimize and preferably eliminate the formation of the interposing graphite layer, we coated nickel substrate with ∼1000 Å thick AlN layer by using pulsed laser deposition and subsequently, subjected them to diamond deposition by hot filament chemical vapor deposition method. It is found that the aluminum nitride layer plays a crucial role in limiting carbon diffusion and inhibiting the formation of graphitic carbon and simultaneously enhancing the nucleation and adhesion of diamond phase.
A Fourier transform spectrometer with fast scanning capability for tokamak plasma diagnostic
Authors: Buratti P. , Zerbini M.
Published: July 2002

Electron cyclotron emission spectra are routinely measured in the FTU tokamak by means of a fast scanning Fourier transform spectrometer. The key element of this instrument is a two-beam interferometer in which the path difference is varied linearly in time by rotation of a helicoidal reflector. The shortest scan time obtained for a path difference excursion of 4 cm was 1.2 ms. The spectrometer has been absolutely calibrated and the measured temperature profiles are in good agreement with those derived from other diagnostics.
An automatic swinging instrument for better neonatal growing environment
Authors: Lu Cheng-Hsing , Luo Ching-Hsing , Chen Yung-Jung , Yeh Tsu-Fuh
Published: July 2002

It is well known that a swing can help infants fall asleep easily. In conditions of deep sleep, infants can grow faster. But how and when to swing (including swing speed and amplitude) for better growth is a serious question. As of now, of concern is that there is no objective quantitative research concerning this topic, although there exist some qualitative studies in the literature. This project is directed to designing a swing system that can simulate a natural or forced swing vibration with a quiet close-loop magnetic driving technique. Both the frequency and amplitude of the system can be changed independently in the range of 0.4–1 Hz and 0.36°–3.6°, respectively. Therefore, the infant’s quantitative physiological signals (e.g., electroencephalogram, energy consumption, sleep duration) can be measured to determine the best method of swinging. This system would help a lot of neonates, especially premature infants whose growth rate is much lower than it is in the mother’s body.
Transient x-ray diffraction used to diagnose shock compressed Si crystals on the Nova laser
Authors: Kalantar D. H. , Chandler E. A. , Colvin J. D. , Lee R. , Remington B. A. , Weber S. V. , Wiley L. G. , Hauer A. , Wark J. S. , Loveridge A. , Failor B. H. , Meyers M. A. , Ravichandran G.
Published: July 2002

Transient x-ray diffraction is used to record time-resolved information about the shock compression of materials. This technique has been applied on Nova shock experiments driven using a hohlraum x-ray drive. Data were recorded from the shock release at the free surface of a Si crystal, as well as from Si at an embedded ablator/Si interface. Modeling has been done to simulate the diffraction data incorporating the strained crystal rocking curves and Bragg diffraction efficiencies. Examples of the data and post-processed simulations are presented.
Low temperature thermal diffusivity measurements of gases by the mirage technique
Authors: Salazar A. , Sánchez-Lavega A.
Published: July 2002

In this article a cryogenic mirage setup to perform thermal diffusivity measurements of gases in the temperature range 77–500 K is presented. The device was calibrated by measuring the temperature dependence of the thermal diffusivity of pure nitrogen and pure helium that have very different thermal properties. The ability of the device was demonstrated by measuring the thermal diffusivity of gas binary mixtures that fit very well the theoretical values obtained from the kinetic theory.
Ultrasonic measurement of stress in railroad wheels
Authors: Schramm Raymond E.
Published: July 2002

The equipment described here generates ultrasonic shear waves using an electromagnetic-acoustic transducer. Precise measurement of the velocity of two orthogonally polarized signals determines the birefringence and allows the calculation of stress. It is necessary to account for the effect of metallurgical texture which can contribute to the birefringence and appear as moderate stress. This system sends a signal through the thickness of a railroad wheel rim, digitizes the first echo, locks onto a cycle, and calculates the time when it crosses zero amplitude. Signal averaging yields the arrival time of a signal at about 90 μs with a standard deviation of 2–4 ns. In screening the residual stress in the rims of cast-steel railroad wheels, this system has a total error of ≈±60 MPa; most of this is due to variability of the texture measured in several stress-relieved blocks cut from wheels. The initial measurements were on wheels in which the manufacture had induced known levels of thermal damage. Results from destructive radial saw cuts through the rims allowed qualitative evaluation of the nondestructive measurements. Most components in this equipment are commercially available.
Measurement of hardness, surface potential, and charge distribution with dynamic contact mode electrostatic force microscope
Authors: Hong J. W. , Park Sang-il , Khim Z. G.
Published: July 2002

Dynamic contact mode electrostatic force microscopy (DC-EFM) was developed as a new operation mode of scanning probe microscope (SPM). By operating EFM in a contact mode with an ac modulation bias, we have improved the spatial resolution and also achieved a complete separation of the topographic effect from other electrostatic force effect overcoming the mixing problem of a topographic effect with other electrostatic effects frequently encountered in the conventional noncontact EFM measurement. DC-EFM can be utilized either as a force microscopy for the surface hardness, or as a potentiometry for the surface potential distribution, or as a charge densitometry for the surface charge density study. This is also applicable to the measurement and control of the domain structure in ferroelectric materials that have a bound surface charge.