bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical Characteristics and Complications of Mechanically Ventilated Children in a Pediatric Intensive Care Unit in Iran: Comparing Different Modes
Authors: Chegeni Touran , Olfat Mehrnaz , Yaghmaie Bahareh , Hassani Seyed Abbas , Sharifzadeh Meisam , Najafi Zeinab , Mohammadpour Masoud
Published: October 2022

Background: Mechanical ventilation (MV) is among the most common therapeutic modalities in pediatric intensive care units (PICU), which works based on a defined ventilation mode. Nowadays, conventional and alternative modes including adaptive pressure control (APC) and non-APC modes are frequently employed. Although MV can be helpful in many cases, it may cause some complications resulting in significant morbidity and mortality. Objectives: This study aimed to investigate the demographic features and complications of mechanically ventilated children in a PICU in Iran, as well as to compare different ventilation modes. Methods: A retrospective case-control study was conducted in PICUs of children’s medical center hospital - a tertiary referral pediatric hospital. Results: Of 66 patients included in this study, 33 patients were treated with APC modes, whereas 33 patients were treated with non-APC modes. The most common indications for intubation were respiratory failure (53%) and loss of consciousness (13.6%). The mean duration for intubation in patients with and without underlying disorder were 11.7 and 5.2 days, respectively (P-value < 0.01). The means of time for intubation in the APC and non-APC groups were 10 and 11.9 days, respectively (P-value = 0.145). A total of 23 (34.8%) patients had complications, including death, misplacement of the endotracheal tube, atelectasis, unplanned extubation, etc. There was no significant difference between groups regarding the rates of complications, except for atelectasis. Thirteen (19.7%) patients had atelectasis (2 patients in APC group (6%) and 11 patients in non-APC group (33.3%)) (P-value = 0.022). The mortality rate was the same for the both groups (P-value = 1). Conclusions: In sum, the most common indication for intubation was respiratory failure. No significant difference was observed among patients treated with the APC, and non-APC modes in terms of the complications occurred, except for atelectasis which occurred more frequently in the non-APC group. Therefore, it was concluded that there was no difference between conventional and alternative modes of mechanical ventilation in terms of morbidity and mortality.
How to Explode an Expressive Body
Authors: Safatle Vladimir ,   Romanian Society for Phenomenology
Published: October 2022

This article aims to discuss the gestural character of Chopin’s pianistic writing. We will focus on the set of Etudes pour piano. We expect to show how the notion of musical expression in Romanticism is dependent of a notion of expressive body always in the limit of decomposition. This could show us how musical expression is a privileged space for a better understanding of the dialectical relationship between form and formless.
L’être des morts selon Jan Patočka
Authors: Lelli Giulia ,   Romanian Society for Phenomenology
Published: October 2022

In this article, I aim to analyse the way in which Jan Patočka explores the being of the dead in his text “Phenomenology of life after death.” I wish to show that this seminal text offers the solution to three main difficulties regarding the being of the dead: those difficulties concern their form of being, their possibility to transform themselves and their ability to act. Following this analysis, I propose a three‑folded thesis: firstly, the being of the dead can be grasped not only through privation but also through more positive forms; secondly, the dead persons can continue to transform themselves when being construed by the living; and thirdly, their action can be prolonged even though they cannot act.
Doubling the World
Authors: Caminada Emanuele ,   Romanian Society for Phenomenology
Published: October 2022

In this paper, I offer an analysis of the thought experiment “Two worlds for one ego” in which Husserl imagines an ego that lives two alternated lives. The thought experiment is designed to question the apodicticity of the world’s singularity. If the ego of the thought experiment is a fully concrete social subject, then the world’s singularity proves to be apodictic. If we were to, conversely, conduct the same experiment with an abstract ego, then the counter‑scenario of a doubling of the world would be tenable if and only if this subject was the sole subject of both worlds. This means, in turn, that a more concrete phenomenological conduction of the experiment demonstrates the limits of methodological solipsism. The paper is tripartite. Firstly, I set out the experiment’s terminological terrain and discuss the systematic questions addressed as well as the phenomenological methods involved. In a second step, I analyse Husserl’s conduction of the thought experiment. Finally, I discuss some of the experiment’s possible applications to anthropology.
Merleau‑Ponty’s Gestural Theory
Authors: Suárez-Gómez Ainhoa ,   Romanian Society for Phenomenology
Published: October 2022

This paper analyses Merleau‑Ponty’s gestural theory focusing on the ontological and epistemological role attributed to the expressive movements of the lived body. The first section argues that Merleau‑Ponty’s phenomenology recognises movement as a primordial phenomenon from which language and thought emerge. This theorisation allows us to identify a type of logos that grants a specific content, sense and value to bodily movements, here conceptualised as a “kin(aesth)etic logos”. The second section of the paper offers a categorisation of different gestures—perceptive, reflexive, habitual and verbal gestures—which show how the kin(aesth)etic logos is actualised in a myriad of daily activities.
Structure, Institution and Operative Essence
Authors: Pazienti Paola ,   Romanian Society for Phenomenology
Published: October 2022

What is the role of gestures within the wider problem of corporeity in Maurice Merleau‑Ponty? How do gestures exemplify and complicate the bodily experience? The aim of this article is to investigate the thematic of gesture in Merleau‑Ponty’s production, with particular attention to the Phenomenology of Perception (1945) and the lessons held at the Collège de France about institution, passivity and nature (1954–60), down to the final indirect ontology inThe Visible and the Invisible. Gestures could be understood as forms (Gestalten), i.e. dynamic structures which express individual and collective behaviours, as well as institutions (Stiftungen), underlying the process of sedimentation and reactivation of meanings. In both cases, gestures have a heuristic or generative function: they shape the individual style in the encounter with the world through “typics” or recurring “motifs”. As a conclusion, the paper argues for the key‑role of gesture, in order to re‑think eidetic intuition as the grasping of operative and emotional essences.
Vertige du moindre geste
Authors: Olcèse Rodolphe ,   Romanian Society for Phenomenology
Published: October 2022

In this article, I consider the gesture confronted with its own impossibility, in situations that open the gesture to a dimension of transcendence. Focusing first on the event of beauty, as it is discussed by Jean‑Louis Chrétien, and on the encountering of the face, as it is considered by Emmanuel Lévinas, this paper envisions a “below” and a “beyond” of the gesture, in exceptional situations where the gesture is faced with an excess, acquiring a dimension of a theopathy. Subsequently, I emphasize that the transcendence that takes gesture beyond itself can inhabit and nourish the daily gestures, and this can be an occasion of pain and difficulties. In this perspective, Simone Weil shows how the repeated gestures of manual labour can become the mirror of supernatural beauty.
Rehabilitation of Aramany Classification I Defect on a Completely Edentulous Patient: A Clinical Case Report.
Authors: S PALANİAPPAN Pl Ranganayakidevi
Published: October 2022

Abstract:
This clinical case report describes a prosthetic rehabilitation for a patient who had partial maxillectomy surgery following the diagnosis of maxillary squamous cell carcinoma in 1991. She was also previously diagnosed with parotid gland pathology on the right and required complete removal of gland along with facial nerve. Her previous prosthesis is 18 years old and claims it not as retentive as before. Intraorally there was a large oval shaped defect on the right side of the maxilla sparing the left alveolus. Defect extends more than 2/3rd of the palatal area with communication to the nasal floor. Presence of buccal frenal pull on the right side on the upper and lower jaws due to the wound contracture on that side of the face. The extraoral facial asymmetry and weakness of facial muscles in this patient may lead to improper denture border seal of the prosthesis. Patient was provided with maxillary acrylic obturator and mandibular acrylic complete denture as a definitive treatment with careful denture extension planning. She was reviewed multiple times till prosthesis stability intraorally was achieved. This improved the prognosis for this patient. The only option for retaining prosthesis in this case, without implants, is optimum engagement of the available soft-tissue undercuts found within the defect space and the non-affected side.
Keywords: Completely Edentulous, Obturator, Facial Nerve, Prognosis, Case Report.
The differences of microleakage smart dentin replacement, glass ionomer cement and a flowable resin composite as orifice barrier in root canal treated
Authors: SOFİANİ Erma , SARİ Emilisa
Published: October 2022

This study was a laboratory experiment. The sample was 27 premolar teeth with one or two mandibular permanent teeth extracted consist of: a smart dentin replacement, glass ionomer cement, and a flowable resin composite. Teeth were prepared using a crown-down method and obturated using gutta percha and AH Plus. After placement of the orifice barrier with a thickness of 4 mm, the teeth were immersed in a 2% methylene blue solution at 37ºC for 24 hours. Teeth sectioned in the buccolingual direction and observation of microleakage using a stereomicroscope (M = 10×). The results showed that microleakage differences between a smart dentin replacement, glass ionomer cement, and a flowable resin composite. The smart dentin replacement has the smallest micro-leakage value of 1.70 but does not differ significantly with the flowable composite resin.
COVID-19 İnfeksiyonunda Nötrofil-Lenfosit Oranının Prognostik Değeri
Authors: YILDIRIM Merve , BULUR Oktay
Published: October 2022

Objective: Serum markers, radiological signs, and clinical findings may help guide the assessment of the prognosis of COVID -19 infection. The neutrophil-lymphocyte ratio is a cheap and easily attainable inflammatory marker. This study aims to investigate whether the neutrophil-lymphocyte ratio is associated with the clinical course of the disease in COVID-19 patients with the non-severe disease

Materials and Methods: We retrospectively analyzed the results of 189 patients who were followed up at the pandemic clinic of Erciyes University, Medical Faculty Hospital. Patients were categorized according to the criteria released by the Republic of Turkey Ministry of Health. That guide classifies the patients as mild-moderate and severe. Patients over 18 years of age who were treated with COVID-19 and whose symptoms were not severe were included in this study. Patients who have missing data were excluded from this study.

Results: The findings showed that there was no significant difference in hospitalized patients concerning neutrophil-lymphocyte ratio levels, white blood cell count, neutrophil count, and lymphocyte count in mild or moderate COVID-19 infected patients at admission and discharge. There was a significant difference in CRP levels between admission and discharge however patients did not progress to a clinical deterioration during the follow-up.

Conclusion: Neutrophil-lymphocyte ratio levels did not change significantly between admission and discharge in mild-moderate patients. In light of previous studies reporting that neutrophil-lymphocyte ratio levels are high in patients with severe COVID-19, the present study suggests that neutrophil-lymphocyte ratio levels are a proper marker for predicting the tendency to severe COVID -19 disease in the follow-up of the patients.
Proteins and Mineral Content of Cultivated Oyster Mushrooms Grown in Kenya
Authors: Nambafu Rachel , Waudo Judith , Nyambaka Hudson
Published: October 2022

Mushrooms are a good source of proteins, vitamins and minerals, and are low in fat and sugars. The various varieties have shown to contain 25 -50% protein and 8 – 12% minerals, with various photochemical compounds. The objective of the study was to assess the proximate composition, mainly crude proteins and trace elements in four varieties (Pleorotus ostreatus (PO), Pleorotus sajor caju (PS), Pleorotus pulmonaries (PP), Pleorotus cintropiletus (PC)) of dried oyster mushrooms. The crude protein compositions of the mushrooms ranged from 35.05% in (PC) to 36.86% in (PO). Mineral composition in the four mushrooms was potassium 54.85 – 73.03 mg/kg, sodium 23.51 – 26.89mg/kg, manganese 0.611 - 0.69 mg/kg, cobalt 1.13 - 1.19 mg/kg, lead 0.95 - 1.24 mg/kg, cadmium 0.17 - 0.18 mg/kg, zinc 0.48 - 0.66 mg/kg, nickel 1.85 - 2.19 mg/kg, chromium 1.33 - 1.64 mg/kg, copper 0.17 - 0.35 mg/kg, iron 1.17 - 1.91 mg/kg, calcium 0.82 - 3.59 mg/kg and magnesium 1.55 - 2.28 mg/kg. The oyster mushrooms varieties grown in Kenya are rich in proteins and minerals.
Regional Time Series Forecasting of Chickpea using ARIMA and Neural Network Models in Central Plains of Uttar Pradesh (India)
Authors: Vennela Bukke , Mishra Ekta Pathak , Gautam Shweta , Mishra Ashish Ratn , Rawat Shraddha
Published: October 2022

Climate and yield prediction are the most important and challenging tasks in modern agriculture during the climate change era. In general, climate and yield are mostly non-linear and highly complicated. India is an agricultural country and most of its economy depends upon agriculture therefore early prediction of climate and yield is necessary for the planned economic growth of our country. This research identifies superior forecasting models of Autoregressive Integrated Moving Average (ARIMA) as well as Artificial Neural Network (ANN) for predicting future climate and chickpea yield. Historical data for the climate and crop were used (1996-2020) and forecasting was done for the next 5 years (2020-2025). By using, RMSE and R2 statistical tools simultaneously, the predictive accuracy of ARIMA and ANN models was compared. By comparing the R2 values of ARIMA (0.591) and ANN (0.96), this study reveals ANN models can be used as more accurate forecasting tools to predict the future climate as well as yield, enabling timely agricultural management.
Genetical Contributions and Combining Ability Analysis in Bitter gourd (Momordica charantia L.)
Authors: Bhardwaj D. R. , Singh Akhilesh Kumar
Published: October 2022

The present study was undertaken to estimate the general and specific combining ability in 10 x 10 diallel set of crosses (excluding reciprocals) in bitter gourd to get 45 hybrids using 10 parents (DVBTG-1, VRBT-94, VRBT-39, VRBT-41, VRBT-49, VRBT-50, VRBT-103, VRBT-63, VRBT-32 and VRBT-6). These 45 F1 along with 10 parents were evaluated in Randomized Block Design with three replications considering 10 characters (days to first male flower anthesis, days to first female flower anthesis, days to first harvest, number of branches/plant, plant height, fruit length, fruit diameter, number of fruits/plant, fruit weight and fruit yield/plant) in bitter gourd. Analysis of variance due to treatment was highly significant for all the traits. The combining ability analysis revealed highly significant differences among the treatments for all the parameters studied. The variances due to sca were higher than the gca for all the characters indicating the predominance of non-additive gene effects. Out of 10 parents’ four parents DVBTG-1, VRBT-49, VRBT-103 and VRBT-32 exhibited significant and   negative g.c.a effects for early female flowering and days to first harvest. Similarly, positive and significant g.c.a effects were shown by DVBTG-1, VRBT-50, VRBT-49, VRBT-103 and VRBT-6 for number of fruits/plant. DVBTG-1 and VRBT-49 showed negative gca effects for the characters except days to 1st harvesting. How VRBT-49 was identified as one of the best general combiners. The cross combinations VRBT-94 x VRBT-32, DVBTG-1 x VRBT-50, VRBT-49 x VRBT-103, VRBT-49 x VRBT-32, VRBT-94 x VRBT-32 and VRBT-41 x VRBT-103 exhibited positive and significant s.c.a effects for first female flower anthesis and days to first harvest. The finding of experiments confirmed the potentiality of DVBTG-1 x VRBT-6, VRBT-94 x VRBT-103, VRBT-41 x VRBT-6, VRBT-94 x VRBT-49, VRBT-39 x VRBT-49 and VRBT-94 x VRBT-39 combination based hybrids for yield/plant. The results of this study also suggest that for improvement of a desirable character, the selected parental line should be of high gca value and their F1s should express high specific combining ability. Significant estimates of additive component (d) along with significance of additive x additive (i) gene interaction-with positive sign pod yield per plant which indicated the presence of increase alleles and associated pair of genes.
The essential role of Glu‐185 and Tyr‐354 residues in the ferroxidase activity of Saccharomyces cerevisiae Fet3
Authors: Bonaccorsi di Patti Maria Carmela , Felice Maria Rosa , Camuti Angela Pia , Lania Amalia , Musci Giovanni
Published: July 2002

The structural determinants required for ferroxidase activity by the yeast multicopper oxidase Fet3 have been partially clarified by site‐directed mutagenesis based on homology modeling. Glu‐185 and Tyr‐354 were substituted with Ala and Phe, respectively. Fet3 E185A retained ca. 5% residual ferroxidase catalytic efficiency, and almost 40% oxidase efficiency. On the other hand, Fet3 Y354F exhibited 50% residual efficiency as a ferroxidase and more than 70% as an oxidase. These results provide new insights in the mechanism of iron binding and oxidation by Fet3, establishing the essential role of Glu‐185 and Tyr‐354, and allowing to dissect ferroxidase from non‐iron oxidase activity.
Engineering Enzymes for Bioorganic Synthesis: Peptide Bond Formation
Authors: Sears Pamela , Wong Chi‐Huey
Published: July 2002

This paper describes recent progress in the development of novel enzymatic catalysts for bioprocessing, especially for peptide bond formation. Techniques ranging from chemical modifications and specific and random mutagenesis to phage display and catalytic antibody induction used to create novel and efficient catalysts are described. The advantages and drawbacks of each technique and future prospects in the field are discussed.
Involvement of carbohydrate on phospholipase A2, a bee‐venom allergen, in in vivo antigen‐specific IgE synthesis in mice
Authors: Okano M , Satoskar Ar , Harn Da , Nishizaki K , Okano M , Masuda Y , Yoshino T
Published: July 2002

Background: Carbohydrates on allergens are known to be important for allergenicity. However, most findings have been made with epitope analysis. In this study, we investigated the involvement of N‐glycan on phospholipase A2 (PLA2), the major allergen of honeybee venom, in in vivo synthesis of specific IgE in mice.

Methods: CBA/J and C57BL/6 mice were sensitized intranasally with either native or deglycosylated PLA2 in the absence of adjuvant. After repeated sensitization, serum Ab titers against PLA2 were determined. PLA2 was deglycosylated chemically with anhydrous trifluoromethanesulfonic acid (TFMS).

Results: CBA/J mice showed PLA2‐specific IgE production after repeated sensitization with native PLA2. They also produced PLA2‐specific IgG1 predominantly, suggesting that Th2‐type Ab production was induced. When we used deglycosylated PLA2 as a competitor in ELISA for detecting PLA2‐specific IgE, deglycosylated PLA2 completely inhibited the binding between native PLA2 and IgE. Deglycosylated PLA2 had the same potential for inducing specific IgE synthesis as native PLA2, since sensitization with deglycosylated PLA2 also elicited IgE production in CBA/J mice.

Conclusions: These results suggest that carbohydrate on PLA2 is less important than previously thought not only as a dominant IgE epitope but also in synthesis of PLA2‐specific IgE in vivo.
Molecular Markers Reveal Cryptic Species Within Polytrichum commune (Common Hair‐Cap Moss)
Authors: Bijlsma R. , van der Velde M. , van de Zande L. , Boerema A. C. , van Zanten B. O.
Published: July 2002

Abstract: Based on morphological characters only, the taxonomy of the moss genus Polytrichum has still not been fully resolved. Application of molecular techniques might clarify some of these problems. Within P. commune s.l., the taxonomic status of several varieties, e.g., P. commune var. commune and P. commune var. uliginosum, is still debated. This study uses allozyme electrophoresis to show that there are two distinct allozyme multi‐locus genotypes within our P. commune samples. These two multi‐locus genotypes coincide with both differences in morphology and differences in habitat association. This division is corroborated by observations from different Danish and Dutch populations. Based on these results, in connection with a genetic comparison of the two infraspecific taxa of P. commune s.l. with a related species P. formosum, we argue that P. commune var. commune and P. commune var. uliginosum are two genetically distinct entities with fixed morphological differences and a considerable niche differentiation. They should, therefore, be regarded as two distinct species: P. commune and P. uliginosum.
Friction in levitated superconductors
Authors: Brandt E. H.
Published: July 2002

A type I superconductor levitated above a magnet of low symmetry has a unique equilibrium position about which it may oscillate freely. In contrast, a type II superconductor has a continuous range of stable equilibrium positions and orientations where it floats rigidly without swinging or orbiting as if it were stuck in sand. A strong internal friction conspicuously indicates the existence and unpinning of flux lines in oxide superconductors levitated above liquid nitrogen. It is shown how these effects follow from the hysteretic magnetization curves and how the energy is dissipated.
Formation of ultrashallow p+-n junctions by low-energy boron implantation using a modified ion implanter
Authors: Hong S. N. , Ruggles G. A. , Paulos J. J. , Wortman J. J. , Ozturk M. C.
Published: July 2002

A conventional ion implanter (Varian Extrion Series 400 implanter) has been modified for the purpose of implanting at ultralow energies (0.5–5 keV). A 35 keV ion beam is decelerated to the desired energy just prior to impacting the substrate, thereby minimizing beam expansion and beam current reduction. The deceleration lens was designed to minimize the variation in energies and incident angles of implanted ions at the target. Computer simulation of the deceleration system indicated that less than a 2° variation in incident angles and a 50 eV variation in ion energies could be expected for 1 keV 11B implantation. Secondary-ion mass spectrometry revealed essentially identical as-implanted boron profiles for 1.35 keV 11B implanted with the modified system and 6 keV BF2 implanted without the modification, indicating successful deceleration. The modified implanter was used to form ultrashallow p+-n junctions via 1 keV 11B implantation coupled with rapid thermal annealing. Results indicate that ultralow-energy B implantation can be used to create junction depths as shallow as 50 nm.
Improvement in the boron doping efficiency of hydrogenated amorphous silicon carbide films using BF3
Authors: Asano A. , Sakai H.
Published: July 2002

Wide optical gap (2.0 eV) boron-doped hydrogenated amorphous silicon carbide films were prepared by the plasma-assisted chemical vapor deposition technique from a SiH4+CH4+BF3+H2 gas mixture for the first time. The film showed a photoconductivity of 1×10−5 S/cm under 1 sun illumination, which was higher by a factor of 5 than the films doped with B2H6.
Wafer fusion: A novel technique for optoelectronic device fabrication and monolithic integration
Authors: Liau Z. L. , Mull D. E.
Published: July 2002

Centimeter-size single-crystal InP or GaAs wafers have been fused together entirely, face to face or side by side, after a heat treatment in a graphite/quartz reactor which can press the wafers together through differential thermal expansion. Diodes formed by fusing p- and n-type wafers showed normal current-voltage characteristics and light emission. Fusion between lattice-mismatched wafers (i.e., InP and GaAs) has also been demonstrated.
Type II phase matching in a β-barium borate optical parametric oscillator
Authors: Bosenberg W. R. , Tang C. L.
Published: July 2002

We report the first demonstration of a type II phase-matched optical parametric oscillator using β-barium borate (BBO) as the nonlinear optical material. The optical parametric oscillator (OPO) is pumped at 354.7 nm and tuning has been demonstrated over 0.48–0.63 μm and 0.81–1.36 μm. The linewidth of the device, without line narrowing elements, is 0.5–3.0 Å, which is dramatically narrower than that of a corresponding type I phase-matched BBO OPO. Experimentally usable conversion efficiencies of 12% have been achieved.
Reduction of the CO2 decomposition in the transversely excited atmospheric CO2 laser discharge plasma by a very small amount of the water vapor
Authors: Hokazono Hirokazu , Obara Minoru
Published: July 2002

Using a comprehensive theoretical model, we have theoretically clarified for the first time that the homogeneous catalytic reaction caused by a very small amount of water vapor (<100 ppm) in the closed-cycle, transversely excited atmospheric (TEA) CO2 laser discharge plasma could considerably reduce the saturation value of the CO2 molecules decomposition. Effects of the water vapor at this concentration level have been overlooked in the previous investigations. A small concentration variation of the residual water vapor in the experimental laser chambers is thought to be one of the reasons for the considerable disagreements among the published data about the CO2 equilibrium decomposition level.
Demonstration of the effects of interface strain on band offsets in lattice-matched III-V semiconductor superlattices
Authors: Nelson J. S. , Kurtz S. R. , Dawson L. R. , Lott J. A.
Published: July 2002

A first principles total energy self-consistent pseudopotential calculation is used to predict the band offset in the lattice-matched superlattice InAs/Al0.8Ga0.2As0.14Sb0.86. We find that inclusion of interface strain changes the character of the band offset from nominally type II to strongly type II. The predicted band offset at the minimum energy configuration is in excellent agreement with the value determined from infrared photoluminescence measurements.
Temperature dependence of femtosecond electromagnetic radiation from semiconductor surfaces
Authors: Hu B. B. , Zhang X.-C. , Auston D. H.
Published: July 2002

We present observation of temperature dependence of optically induced femtosecond electromagnetic radiation from several semiconductors. When the sample temperature decreases from 280 to 80 K, over 4 times and 21 times increases of the radiated peak field and radiated energy have been found. A large shift of the frequency spectrum of the radiation was observed when the InSb sample temperature was tuned over this range.
Processing and properties of nanophase amorphous metallic alloys: Ni-Ti
Authors: Averback R. S. , Hahn H. , Höfler H. J. , Logas J. C.
Published: July 2002

Amorphous Ni-Ti alloys were synthesized by producing nanoscale amorphous Ni-Ti particles and compacting these powders, in situ, in a high vacuum environment. X-ray diffraction measurements revealed that crystallization occurs in these alloys in the temperature range 450–550 °C, although measurements of electrical resistivity and heat release showed that other relaxation processes occur at lower temperatures. The Vicker’s hardness of these alloys is ≊350 kg/mm2. The results are discussed in terms of interparticle or grain boundaries in the amorphous alloy.
1.54 μm room-temperature luminescence of MeV erbium-implanted silica glass
Authors: Polman A. , Lidgard A. , Jacobson D. C. , Becker P. C. , Kistler R. C. , Blonder G. E. , Poate J. M.
Published: July 2002

MeV erbium implantation doping of 10-μm-thick silica glass films on a Si substrate is studied with the aim of incorporating the rare-earth dopant on an optically active site in the silica network. As-implanted samples (3.5 MeV, 5×1015 Er ions/cm2) show a strong luminescent transition at a wavelength of 1.54 μm, even at room temperature, corresponding to an intra-4f transition of Er3+. Thermal annealing at temperatures up to 900 °C increases the luminescence intensity by a factor of 2 to 3. For temperatures above 1000 °C the intensity decreases drastically as a result of Er precipitation. The lifetime of the excited state is in the order of 10 ms. Photoluminescence studies at 4.2 K are used to identify implantation-induced damage.
Comparison of the selective adsorption and reactivity behavior of WF6 and TaF5 on SiO2 and polyimide surfaces
Authors: McFeely F. R. , Terminello L. J. , Kowalczyk S. P.
Published: July 2002

The initial stages of WF6 and TaF5 adsorption on SiO2 and polyimide surfaces were investigated by photoelectron spectroscopy. WF6 selectively adsorbs on Si relative to SiO2 and polyimide, while TaF5 exhibited nonselective adsorption behavior. This trend is explained by differences in molecular structure and suggests a general basis for predicting selective deposition.
Properties of SiO2/Si/GaAs structures formed by solid phase epitaxy of amorphous Si on GaAs
Authors: Callegari A. , Sadana D. K. , Buchanan D. A. , Paccagnella A. , Marshall E. D. , Tischler M. A. , Norcott M.
Published: July 2002

We have achieved solid phase epitaxy of thin amorphous Si layers on GaAs using in situ plasma processing and subsequent annealing. High-resolution transmission electron microscopy of the SiO2/Si/GaAs structure shows that a Si layer ≂20 Å thick epitaxially crystallizes on GaAs after annealing at ≂570 °C in N2. Metal-oxide-semiconductor capacitors fabricated on these structures confirm the high quality of these interfaces. By comparing a high- frequency (100 kHz) capacitance-voltage curve with a quasi-static one, interface state densities as low as 4×1012 eV−1/cm−2 were measured on both n- and p-type GaAs.
High-speed modulation of strained-layer InGaAs-GaAs-AlGaAs ridge waveguide multiple quantum well lasers
Authors: Offsey S. D. , Lester L. F. , Schaff W. J. , Eastman L. F.
Published: July 2002

Strained-layer In0.35Ga0.65As-GaAs-AlGaAs graded index separate confinement heterostructure multiple quantum well lasers were grown by molecular beam epitaxy and processed as ridge waveguide structures. Devices with 3 μm×200 μm cavities have threshold currents of 18 mA (3000 A/cm2) and optical waveguide losses of 4.2 cm−1. The microwave modulation bandwidth of a 3 μm×200 μm device was determined to be 19.5 GHz, which exceeds the 15.5 GHz reported for multimode index-guided devices, and is the highest direct modulation bandwidth reported for a quantum well laser.
Raman scattering as a compositional probe of II-VI ternary semiconductor nanocrystals
Authors: Tu A. , Persans P. D.
Published: July 2002

We show how Raman optic-mode peak positions and relative intensities can be used in a straightforward way to determine crystallite composition in CdSxSe1−x nanocrystals embedded in glass. These Raman techniques are particularly useful for low-concentration or small-crystallite-size composites where x-ray diffraction is not a viable technique for structural characterization of crystallites.
Far-infrared photoresponse of the InAs/GaInSb superlattice
Authors: Campbell I. H. , Sela I. , Laurich B. K. , Smith D. L. , Bolognesi C. R. , Samoska L. A. , Gossard A. C. , Kroemer H.
Published: July 2002

We describe the growth and characterization of the InAs/GaInSb superlattice on GaSb substrates. We present far-infrared (λ∼10 μm) photoabsorption and photoconductivity spectra which are in good agreement with theoretical predictions for the photoresponse of this spatially indirect superlattice. We report time-resolved photoconductivity measurements in which two response times are observed. We interpret the fast, 2 ns decay as resulting from electron-hole recombination via deep defect levels and the slow, 2 μs decay as resulting from recombination of a small fraction of the photogenerated minority carriers which become trapped at a defect site.
Photon-assisted nitridation of GaAs(100) at liquid-nitrogen temperature
Authors: Ruckman M. W. , Cao Jianming , Park Ken T. , Gao Yongli , Wicks G. W.
Published: July 2002

We show that nonmonochromatic synchrotron radiation promotes reactions at liquid-nitrogen temperature (∼80 K) between NH3 and molecular beam epitaxy grown GaAs(100) which produces a thin nitride film. The photon-assisted reaction causes changes in the valence band and core level photoemission spectra from GaAs(100) which are similar to those reported for nitridation by a nitrogen plasma.
Surface characterization of epitaxial, semiconducting, FeSi2 grown on Si(100)
Authors: Alvarez J. , Hinarejos J. J. , Michel E. G. , Gallego J. M. , Vazquez de Parga A. L. , de la Figuera J. , Ocal C. , Miranda R.
Published: July 2002

We have identified the composition and range of thermal stability of FeSi and FeSi2 films grown on Si(100) by solid phase epitaxy and reactive deposition epitaxy. Evidence for the semiconducting character of FeSi2 is obtained from photoemission measurements giving a low density of states at the Fermi level. Si enrichment at the outer surface of the silicides at temperatures much lower than previously thought has been found by depth profiling. Scanning tunneling microscopy reveals a rather inhomogeneous growth with a tendency towards epitaxial growth favored by the presence of surface steps on the Si substrate.
High critical-current densities in (Tl0.5Pb0.5)Sr2Ca2Cu3O9 with T
c up to 115 K
Authors: Liu R. S. , Zheng D. N. , Loram J. W. , Mirza K. A. , Campbell A. M. , Edwards P. P.
Published: July 2002

A high critical-current density was observed in the material (Tl0.5Pb0.5)Sr2Ca2Cu3O9. Based on magnetic-hysteresis measurements, this single (insulating) Tl-O layer material has a Jc value of 1.24×105 A/cm2 when measured at a temperature of 77 K and a field of 1 T. This value of Jc is comparable to that measured here for YBa2Cu3O7 (1.04×105 A/cm2), having single-conducting Cu-O chains, but considerably greater than the value for the material Tl2Ba2Ca2Cu3O10 with double (insulating) Tl-O layers in which no hysteresis was observed under these same conditions. Our results from specific heat measurements indicate that the (Tl0.5Pb0.5)Sr2Ca2Cu3O9 compound has a three-dimensional character due to the enhancement of the superconducting coupling along the c axis between the Cu-O planes and thus results in an increase in Jc compared to the two-dimensional Bi- and Tl-2212 and 2223 [e.g., (Bi or Tl)2(Sr or Ba)2CaCu2O8 and (Bi or Tl)2(Sr or Ba)2Ca2Cu3O10, respectively] compounds. We believe that the high Jc is associated with an increase in the irreversibility field, rather than an increase in pinning centers.
High quantum efficiency luminescence from a conducting polymer in solution: A novel polymer laser dye
Authors: Moses Daniel
Published: July 2002

A novel dye laser based on the soluble conducting polymer poly[2-methoxy, 5-(2′ ethyl-hexyloxy)-p-phenylenevinylene], MEH-PPV, has been demonstrated. Laser action has been tested in a transverse cavity configuration where the conducting polymer laser was pumped by light pulses generated from the second harmonic radiation of a Q-switched Nd:YAG laser. The performance of MEH-PPV in solution as a laser dye was compared to that of rhodamine 6G in solution under identical conditions. The results indicate that the quantum yield of MEH-PPV laser is comparable to that of rhodamine 6G.
Comment on ‘‘Occupancy of the DX Center in N-Al0.32Ga0.68As under uniaxial stress’’
Authors: Li Ming-fu , Yu Peter Y. , Weber E. R.
Published: July 2002

A discussion is given on the various DX center models in connection wi some recent experiments concerning DX centers in n−AlGaAs under uniaxial stresses. (AIP)
High frequency attenuated total internal reflection light modulator
Authors: Solgaard O. , Ho F. , Thackara J. I. , Bloom D. M.
Published: July 2002

The modulation efficiency and bandwidth limitations of a new type of light modulator, the attenuated total internal reflection modulator (ATRM), are described. The ATRM is based on coupling a light beam to a surface plasmon wave, and its fabrication is compatible with GaAs integrated circuit technology. We demonstrate modulation to 22 GHz (the extrapolated 1.5 dB optical modulation bandwidth is 26 GHz) and show that devices with high modulation index can be built using existing materials.
Re-evaluation of the thermal stability of optically nonlinear polymeric guest-host systems
Authors: Stähelin M. , Burland D. M. , Ebert M. , Miller R. D. , Smith B. A. , Twieg R. J. , Volksen W. , Walsh C. A.
Published: July 2002

Guest-host polymer systems with potential use in electro-optic devices are discussed. The polymer host is a polyimide and the guest chromophores are 2,4,5-triarylimidazoles (lophines). Poling stabilities have been obtained by extrapolating the second harmonic generation decay using a stretched exponential function and extrapolated lifetimes greater than a year at 80 °C have been obtained. In addition, an apparent relationship between the stability of poled order and the glass transition temperature is discussed.
Comparison of electronic transport in boron-doped homoepitaxial, polycrystalline, and natural single-crystal diamond
Authors: Malta D. M. , von Windheim J. A. , Fox B. A.
Published: July 2002

Hall-effect and resistivity measurements were performed on simultaneously deposited B-doped homoepitaxial and polycrystalline diamond films, as well as a (100)-oriented type-IIb natural diamond crystal, over a temperature range of 140–600 K. At 298 K, the respective Hall mobilities for the homoepitaxial and polycrystalline films were 519 and 33 cm2/V s, while the active carrier concentrations were both approximately 2×1014 cm−3. For the natural diamond, a Hall mobility of 564 cm2/V s and a carrier concentration of 2×1013 cm−3 were measured at room temperature. A comparison of the transport behavior of the three specimens indicates that the electronic properties of diamond grown by chemical vapor deposition are potentially of equal or greater quality than natural diamond and that the transport properties of polycrystalline films are severely degraded by the effects of grain boundaries.
Detection and lifetime measurement of single molecules in flowing sample streams by laser-induced fluorescence
Authors: Wilkerson Charles W. , Goodwin Peter M. , Ambrose W. Patrick , Martin John C. , Keller Richard A.
Published: July 2002

The detection and measurement of fluorescence lifetimes of single Rhodamine-110 molecules in a flowing, aqueous sample stream is described. Time-correlated single-photon counting, used in combination with mode-locked picosecond pulsed excitation, allows the detection of single fluorescent molecules in the presence of significant solvent Raman and Rayleigh backgrounds. The fluorescence lifetime of a detected molecule is estimated from the record of arrival times (relative to the excitation pulse) of photons detected during the molecule’s passage through the ∼1 pL excitation volume.
111 kW (0.5 mJ) pulse amplification at 1.5 μm using a gated cascade of three erbium-doped fiber amplifiers
Authors: Desthieux B. , Laming R. I. , Payne D. N.
Published: July 2002

The generation of high peak power pulses by amplification of the output from a distributed feedback diode laser is demonstrated using a cascade of three erbium-doped fiber amplifiers (EDFAs) separated by an acousto-optic gate. The optimized amplifier chain consisted of two high efficiency single-mode EDFAs pumped with 40 mW at 980 nm, followed by a multimode EDFA pumped with 1.5 W at 978 nm. At low repetition rates, peak output powers of 111 kW and energies of 0.5 mJ at 1.534 μm were obtained.
Monolayer chemical beam etching: Reverse molecular beam epitaxy
Authors: Tsang W. T. , Chiu T. H. , Kapre R. M.
Published: July 2002

We have developed an etching process with real-time counting of each monolayer removed, thus achieving etching with monolayer precision and control. This is an exact reversal of molecular beam epitaxy or more specifically in this case, chemical beam epitaxy (CBE). This new etching capability which we refer to as monolayer chemical beam etching (ML-CBET) is achieved by employing in situ reflection high-energy electron diffraction (RHEED) intensity oscillation monitoring during etching. Etching is accomplished in high vacuum by injecting AsCl3 directly into a CBE growth chamber impinging on a heated GaAs substrate surface. Having both epitaxial growth and etching integrated in the same process and both capable of ultimate control down to the atomic layer precision represents a very powerful combination. This permits instant switching from growth to etching and vice versa, clean regrown interfaces critical for device applications, direct modification of surface chemistries during etching or growth, and high temperature etching (500–570 °C for InP and 500–650 °C for GaAs) unachievable in conventional etching processes. The temperature and flux dependence of etching rates are also studied using RHEED oscillations. Results indicate that ML-CBET is studied predominantly via a layer-by-layer mechanism under the present etching conditions.
SiO2 thin film deposition by radio frequency oxygen plasma enhanced laser ablation from Si
Authors: Chen T. P. , Bao Tien-I , I Lin
Published: July 2002

A novel process of room temperature deposition of thin SiO2 film by laser ablation from a c-Si target in a low pressure (<5 mTorr) rf oxygen magnetron plasma background was developed. The gas phase reactions which usually dominate in other high pressure reactive ablation processes are suppressed and the energetic particles from the target have good transport to the substrate in the low pressure background. The surface reactions are continuously enhanced after the arrival of Si particles by the high fluxes of oxygen radicals and ions from the steady state magnetron discharge. The deposition of stoichiometric, less disorder, dense, and water free films are demonstrated.
Gettering and hydrogen passivation of edge-defined film-fed grown multicrystalline silicon solar cells by Al diffusion and forming gas anneal
Authors: Sana Peyman , Rohatgi Ajeet , Kalejs Juris P. , Bell Richard O.
Published: July 2002

This study shows for the first time that a combination of Al treatment on the back, oxide passivation on the front, and 400 °C forming gas anneal in the presence of Al, raised the double-layer antireflection-coated edge-defined film-fed grown (EFG) silicon cell efficiency from 7.8% to 14.1%. Front oxide passivation contributed an ∼0.8% increase in absolute cell efficiency, Al diffusion on the back increased the efficiency by 1.4% (absolute), and the forming gas anneal (FGA) after the Al diffusion improved the cell efficiency by an additional 4.1% (absolute). A combination of the above three steps improved the EFG cell efficiency by 6.3%, indicating that the above three effects are complimentary. Oxide passivation reduced front surface recombination velocity and Al diffusion, while FGA improved diffusion length via gettering. We propose that the large increase in cell efficiency produced by the forming gas anneal results from bulk defect passivation by atomic hydrogen generated in the processing.
Surface ordering of the molecular beam epitaxially grown GaAs(001)-2×4-As reconstruction
Authors: Zhou Junming , Xue Qikun , Chaya Hideo , Hashizume Tomihiro , Sakurai Toshio
Published: July 2002

Our scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED) showed that the intensity of the two-fourths fractional order feature in the RHEED pattern for the GaAs(001)-2×4 structure reflects the degree of ordering of the vacancy rows. The STM images show a high degree of surface ordering only when the RHEED produces nearly the equal intensity sharp streaks for all the fourfold fractional order diffraction. Two possible mechanisms are suggested to explain the observed STM-RHEED correlation.
Atomic-scale wear properties of muscovite mica evaluated by scanning probe microscopy
Authors: Miyake Shojiro
Published: July 2002

Atomic-scale wear properties of muscovite mica were evaluated in terms of friction force and surface topographic changes using a scanning probe microscope. Friction from a load of 100–300 nN generated a 1-nm-deep wear groove which corresponded to the depth from the surface of one cleavage plane to the surface of the next periodic cleavage plane. The atomic image of the bottom surface of the wear groove corresponds to the basal plane of mica.
Stabilization of face-centered-cubic Mn films via epitaxial growth on GaAs(001)
Authors: Jin X. , Zhang M. , Dong G. S. , Xu M. , Chen Y. , Wang Xun , Zhu X. G. , Shen X. L.
Published: July 2002

The epitaxial growth of fcc Mn films on the GaAs(001) surface has been achieved. The films are studied by in situ reflection high energy electron diffraction (RHEED) and ex situ x-ray diffraction (XRD). The lattice parameters of the metastable Mn films are determined to be 0.362 nm. A transition region composed of a Mn-Ga-As alloy is formed at the Mn/GaAs interfaces and is clearly verified by XRD measurements.
Repetitively pulsed relativistic klystron amplifier
Authors: Levine Jerrold S. , Harteneck Bruce D.
Published: July 2002

This letter reports on the operation of a repetitively pulsed relativistic klystron amplifier at 200 pps. The electron beam was reproducibly modulated to ≳60%. Using a 5 kA, 500 kV electron beam and a 500 kW magnetron as inputs, we extracted 3.3 kW average power in 80 ns FWHM pulses of 250–300 MW peak power at 1.3 GHz. Limitations that are directly attributable to the repetitive pulsing at these levels have not been observed.
Very-low-noise amplifier for low-temperature pulsed NMR experiments
Authors: Bloyet D. , Lepaisant J. , Varoquaux E.
Published: July 2002

We describe the design, schematics, and performances of a low-noise preamplifier for pulsed nuclear-magnetic-resonance (NMR) experiments in the range 0.1–1 MHz with a noiseless (cooled below liquid-helium temperature) pickup coil. This preamplifier operates at room temperature and exhibits an order-of-magnitude improvement in noise power per unit bandwidth over previously used preamplifiers. All significant contributions to the noise are carefully identified and a detailed analysis of the noise performance of a cascode differential pair of JFETs is given. Application to very-low-temperature thermometry by NMR in pure platinum powder is discussed as a practical example.
Algorithm for ascertaining linear range of turbine flow meters
Authors: Jones Frank E.
Published: July 2002

The conventional practice of expressing the relationship between volume flow rate, Q, and frequency, f (or pulse rate) for turbine flow meters by the ‘‘K factor’’ is examined. Curvature in plots of K against f due to the existence of a nonzero intercept in the linear equation relating f to Q is illustrated using calibration (water and type II hydrocarbon) data. An algorithm which enables the actual linear range of turbine flow meters to be simply and easily ascertained is presented. The very significant improvement in linearity accomplished by the use of the algorithm is illustrated for the calibration data.