bluuebunny/crossref_metadata_2025 huggingface dataset:
3D CT Volumetry of Varient Gastric Reservoir after Sleeve Gastrectomy and Its Relation to Clinical Outcome
Authors: Hammad Dina Mostafa , Khadra Rania Sobhey Abo , Younes Rasha Lotfy , Sherif Mohamad Fouad
Published: May 2022

Background: The role of radiology in gastric bariatric surgery is no longer limited for detection of postoperative complications, but also it extends to evaluate the role of surgical reduction of gastric size in body weight changes after surgery. The aim of this work was to assess the ability of 3D CT volumetry of variant gastric reservoir after sleeve gastrectomy and its relation to clinical outcome.

Methods: This prospective study that was carried out on 30 obese patients who was candidates for gastric sleeve surgery for the first time. All patients were subjected to clinical examinations [blood pressure, pulse rate and respiratory rate], pre-operative preparation: Blood testing, liver function, electrolytes and hormonal tests, an upper gastrointestinal (GI) endoscopy, abdominal ultrasound (US), echocardiography and CT volumetry

Results: There was no statistically significant correlation between body weight and gastric volume preoperative but a significant relation postoperative. Body weight, Body mass index (BMI) and gastric volume were significantly lower post-operative compared to pre-operative (P<0.001).

Conclusions: Computed tomography scan plays a significant role being a comprehensive imaging tool sensitive for accurate diagnosis of any suspected complication. Also, 3D CT volumetry adds more value in the evaluation of the new gastric pouch volume. In the setting of bariatric sleeve gastric surgery, MSCT volumetric assessment of the stomach is the gold standard imaging tool for evaluating gastric size in the postoperative phases.
Cerebroplacental Doppler Ratio and Cerebrouterine Doppler Ratio in Predicting Neonatal Outcome in Preeclamptic Pregnant Women
Authors: Elsharkawy Reem Taha , Khyat Ahmed Mahmoud El , Dakhakhni Raghda Ahmed El , Omar Mona Khaled , Hamoda Mahmoud Salah El Deen
Published: May 2022

Background: Umbilical artery and middle cerebral artery Doppler ultrasound clearly depict the information about placental resistance and the changes in the fetal hemodynamics in response to it. The aim of this work was to assess the role of cerebroplacental ratio and cerebrouterine ratio in prediction of neonatal outcome in preeclamptic women.

Methods: This prospective observational study was carried out on 110 pre eclamptic women. Patients were divided into two groups: Preeclampsia with severe (n=58) and preeclampsia (n=52). All patients were subjected to laboratory testing (complete blood count (CBC), coagulation profile, liver and kidney function tests, 24 hours urine sample collection) and ultrasonographic scanning trans - abdominal sonographic examinations.

Results: The cut off value of CP ratio was 1.09 with sensitivity 84%, specificity 89%, PPV (positive predictive value) 94%, NPV (negative predictive value) 73% and accuracy 85% while the study cut off value of CU ratio was 1.3 with sensitivity 97%, specificity 93%, PPV 95%, NPV 95% and accuracy 95%. UTA, UMBA, MCA, CP and CU were significantly higher in Preeclampsia with severe than Preeclampsia (P value <0.05).

Conclusions: Most of unfavourable neonatal outcome associated with abnormal cerebroplacental and cerebrouterine ratio so cerebroplacental and cerebrouterine ratio were complementary to each other in predicting the adverse neonatal outcomes.
Efficacy of and Safety of Secukinumab in Psoriasis Vulgaris: A Prospective Study
Authors: Tirmizi Syeda Shahmoona , Iqbal Tayyaba , Ather Saher , Farooq Nadia , Mansoor Maria , Asar Marium , Kapadia Naseema , Ain Qurrat Ul
Published: May 2022

Objective: Psoriasis is an immune mediated inflammatory skin disorder that potentially requires lifelong management. Different therapies treating psoriasis have been recognized wherein Secukinumab is a fully humanized, IL-17A monoclonal antibody that has been approved by US Food and Drug administration for the treatment of moderate to severe plaque psoriasis. Therefore, this study targeted to assess the efficacy of Secukinumab in patients with moderate to severe psoriasis.

Methodology: This was a Prospective interventional multicenter study conducted by using consecutive sampling technique. The duration of study was about one year. The sample size was 138. Adult patients between 18-65 years of either gender with clinical diagnosis of psoriasis vulgaris involving scalp, face, hands, or genital areas, were include. Treatment initiated by the administration of a single dose of 300 mg Secukinumab subcutaneously for 4 weeks then monthly for 52 weeks. Paired t-test was applied to assess the difference in the PASI score at various follow ups.

Results: The study results showed that out of 138 patients, 112(81.2%) were males and 26(18.8%) were females and their mean age was 40.47±9.55 years. As far as distribution of disease is concerned, 117(84.8%) patients reported Plaque Psoriasis, 57(41.3%) patients reported Scalp Psoriasis, 9(6.5%) patients reported nail Psoriasis, 11(8.0%) patients reported Palmoplantar Psoriasis, and 5(3.6%) patients reported Erythrodermic psoriasis. For the comparison of Secukinumab treatment under PASI scores, there was statistically significant reduction observed from mean of baseline PASI scores till 1 week (p<0.001), till 2 week (p<0.001), till 4 week (p<0.001), till 8 week (p<0.001). The improvement in mean PASI score from baseline to 1 year was 91%.

Conclusion: This study concluded that Secukinumab is a highly effective, rapid-acting biological therapy with no obvious adverse effects. Additionally, it was seen that secukinumab significantly reduced the baseline PASI score till 8 week rapidly in moderate and severe psoriasis.
Association of Postoperative Complications with Anemic Women Underwent Gynecologic and Obstetric Surgeries
Authors: Khan Farah , Jamshed Saira , Devi Ramna , Waleem Naureen , Hussain Razia , Khalid Sarwat , Siddiqui Ahsan Ali
Published: May 2022

Objective: Preoperative anemia among women has been recognized as a risk factor for adverse postoperative complications following gynecologic and obstetric surgeries. Therefore, this retrospective analysis was conducted to assess the association of postoperative complications and comorbidities with anemia in women underwent gynecologic and obstetric surgeries.

Methodology: A retrospective study was carried out in the Department of Obstetrics and Gynecology of Hamdard hospital, Karachi by using non-probability, purposive sampling technique. A total of 200 women were chosen for this study wherein 89 women were anemic and 111 were non-anemic. Duration of the study was one year from July 2018 – June 2019. Adult female patients of 18 to 65 years having elective or emergency surgical procedure were included. Chi square test was applied to evaluate the association between religion, socioeconomic status, comorbidities, and postoperative complications with anaemia.

Results: The study results showed that the mean age of studied women was found 32.04±7.79 years and mean hospital stay was reported 3.38±1.08 days. Regarding Comorbidities, 89(100.0%) non diabetic were anemic while 6(5.4%) diabetic and 105(94.6%) non-diabetic were non-anemic with a significant association of diabetes with anemia (p=0.026). Regarding postoperative complications, significant association of fever was found with anemia (p<0.001). Moreover, 71(79.8%) anemic and 39(35.1%) non-anemic reported postoperative nausea and vomiting with a significant association between them (p<0.001). As far as wound infection is concerned, significant association of wound infection was observed with anemia (p=0.020).

Conclusion: This study concluded that postoperative fever, nausea and vomiting were observed significantly higher in anemic women than non-anemic underwent gynecologic and obstetric surgeries. Wound infection was also significantly associated with anemia. Therefore, educational and nutritional policies should be planned to persuade women to use iron-rich diet in order to decrease the burden on patients facing these complications.
Urogynecology and pelvic reconstructive surgery: Office preoperative evaluation of the incontinent female
Authors: Ostergard D.R.
Published: July 2002

Successful research outcomes in the treatment of genuine stress incontinence depend upon correct preoperative urodynamic evaluation. These procedures and how they are used for diagnosis and the selection of the correct surgical procedure are discussed.
Extraperitoneal pelvic lymphadenectomy to complement vaginal operations for cervical and endometrial cancer
Authors: Massi G , Susini T , Amunni G
Published: July 2002

Objective: The aim of the current study was to test the applicability of a personal modification of Mitra extraperitoneal pelvic lymphadenectomy in combination with radical vaginal operations for treatment of endometrial and cervical cancer. Method: In a prospective series, 82 patients were submitted to extraperitoneal pelvic lymphadenectomy. In 34 cases of stage I endometrial cancer the procedure was combined with a class I vaginal hysterectomy and in 48 cases of cervical cancer stage Ib‐IIIb lymphadenectomy was associated with a class II or III radical vaginal hysterectomy. Type of anesthesia, number of lymph nodes removed, operating time, blood loss and postoperative complications were recorded. Result: The operation was performed with spinal anesthesia in 43% of the cases. Thirty‐seven patients (45%) were high surgical risk because of associated diseases. The median operative time for lymphadenectomy was 20 min for each side; the vaginal procedures took a median of 25 min (class I) and 40 min (class II‐III). Blood transfusions were necessary in seven cases (8.5%). A median of 26 lymph nodes were removed from each patient. Lymphocyst occurred in seven patients (8.5%), retroperitoneal hematoma in two and retroperitoneal abscess in one. Conclusion: Extraperitoneal pelvic lymphadenectomy has proven to be a safe and quick technique to complement vaginal operations for endometrial and cervical cancer. Specific features of this approach are: (1) fast, timesaving procedure; (2) possible use of spinal anesthesia; and (3) applicability in high surgical risk patients.
Judicious choices: designing courts in postcommunist politics☆
Authors: Smithey Shannon Ishiyama , Ishiyama John
Published: July 2002

One area which has been generally overlooked in the literature on institutional choice in post communist politics has been the design of judicial institutions. This paper seeks to evaluate a number of different explanations for judicial systems choice in post communist politics, especially those which emphasize the influence of socio-cultural factors, economic factors, the judicial legacies of the past, and political bargaining. As an empirical test of these explanations, we examine variations in the amount of judicial power that constitution makers granted to the constitutional courts in the countries of the former Soviet Union, Mongolia, and Eastern Europe.
Acoustic superlattice of LiNbO3 crystals and its applications to bulk-wave transducers for ultrasonic generation and detection up to 800 MHz
Authors: Zhu Yong-yuan , Ming Nai-ben , Jiang Wen-hua , Shui Yong-an
Published: July 2002

In this letter theoretical calculations and experimental results of ultrasonic generation and detection up to 800 MHz using an acoustic superlattice of LiNbO3 crystals are reported. The experiment is in good agreement with theory. Transducers with an insertion loss of nearly 0 dB at 555 MHz and a 5.8% 3 dB bandwidth have been made.
Formation of silicon carbide particles behind shock waves
Authors: Carmer Craig S. , Frenklach Michael
Published: July 2002

The formation of silicon carbide powder in a 3% SiH4-3% CH4-Ar mixture was studied in a shock tube. The experiments were conducted at the temperature of 800–3650 K, pressures of 0.46–4.16 atm, and reaction times of 1–2 ms. The progress of reaction was monitored by the attenuation of a He-Ne (633 nm) laser beam. Powders collected at the end wall of the tube were identified to be β-SiC and at high temperatures contained particles having sizes up to 0.5 μm. The large particles had the form of thin single-crystal platelets with hexagonal and truncated triangular shapes. The transmitted laser light intensity as a function of reaction time exhibited a pronounced minimum at incident shock temperatures above 1700 K. A reaction model is proposed that explains the experimental observations. It is postulated that SiC particles are nucleated homogeneously, along with Si particles. The latter are etched by the products of methane pyrolysis and the chemical species formed by the etching add to the growth of SiC particles.
Γ- and X-state influences on resonant tunneling current in single- and double-barrier GaAs/AlAs structures
Authors: Rousseau Kenneth V. , Wang K. L. , Schulman J. N.
Published: July 2002

We have calculated the resonant tunneling current of electrons in single- and double-barrier GaAs-AlAs heterostructures in the (001) direction. A ten-band empirical tight-binding model is used in which the wave function is propagated through the structure from atom to atom using transfer matrices. We find that electrons generally follow a Γ-Γ-Γ-Γ-Γ or Γ-X-X-X-Γ path through the double-barrier devices, and present curves that show Γ resonances and X resonances as distinct peaks in the transmission coefficient. The tunneling current is calculated and the influence of the different types of resonances is discussed for a double-barrier device. The existence of resonances in the AlAs barriers suggests that negative differential resistance effects can exist in single-barrier devices.
I
n s
i
t
u processing of epitaxial Y-Ba-Cu-O high T
c superconducting films on (100) SrTiO3 and (100) YS-ZrO2 substrates at 500–650 °C
Authors: Singh R. K. , Narayan J. , Singh A. K. , Krishnaswamy J.
Published: July 2002

We report the formation of excellent quality epitaxial YBa2Cu3O7 films on (100) SrTiO3 and (100) ZrO2 (yttria stabilized) substrates in the temperature range of 500–650 °C by XECl excimer laser ablation in a 0.2 Torr oxygen ambient. By applying a dc bias voltage of +300 V to an interposing ring, we were able to reduce the substrate temperatures from 650 to 500 °C for obtaining epitaxial films. The quality of the epitaxial films was found to decrease with temperature, particularly below 550 °C. The thickness of the superconducting films was varied from 500 to 5000 Å with superconducting transition temperatures Tc (zero resistance) varying from 87 to 90 K for 650 °C deposits. The critical current density Jc of films was found to vary linearly with temperature with values of (zero magnetic field at 77 K) 5.0×106 and 1.0×106 for films deposited at 650 °C on (100) SrTiO3 and (100) yttria-stabilized zirconia substrates, respectively. X-ray diffraction, transmission electron microscopy, electron channeling patterns, and Rutherford backscattering (RBS)/channeling showed excellent epitaxial quality of films on both substrates with best values of minimum ion channeling yield of 3.5% on (100) SrTiO3 substrates.
Recording experiments in magneto-optical disks using ultrathin Co/Pt and Co/Pd media
Authors: Hashimoto S. , Matsuda H. , Ochiai Y.
Published: July 2002

Magneto-optical media using ultrathin Co/Pt and Co/Pd films were prepared on 2P (photopolymer) glass substrates with a double-layer disk structure. Thermomagnetic writing was successfully made in the magneto-optical disks by the relatively low laser power above 3 mW. The values of the C/N ratio were 50 dB for the Co/Pt disk and 45 dB for the Co/Pd disk at a bit length of 5 μm. Clear and regular bit domains were observed even in the shorter recorded bit length.
Measurement of the x-ray power from transition radiators
Authors: Piestrup M. A. , Moran M. J.
Published: July 2002

We report the measurement of the x-ray power from four transition radiators. The average power from a 44 μA, 104 MeV electron beam penetrating a stack of fifteen 1.5-μm-thick aluminum foils was 0.7 mW at a peak photon energy of 1.56 keV with an approximate bandwidth of 40%. The peak power from the same stack in a 17 ns pulse was 58 W. Foil stacks constructed of Mylar, parylene, or boron were either distorted or destroyed by exposure to the high average current electron beam.
Josephson weak links in thin films of YBa2Cu3O7−x induced by electrical pulses
Authors: Robbes D. , Miklich A. H. , Kingston J. J. , Lerch Ph. , Wellstood F. C. , Clarke John
Published: July 2002

A method is described for fabricating superconducting weak links in thin films of YBa2Cu3O7−x grown in situ by laser deposition. Carefully controlled electrical pulses applied to patterned bridges at 77 K are shown to reduce the critical current from initial values of typically 10 mA to values as low as 20 μA. The current-voltage characteristics of the Josephson weak links so formed exhibit constant-voltage current steps that oscillate in amplitude as the applied microwave power is increased, implying that the current-phase relation is periodic but not necessarily sinusoidal.
Spontaneous vitrification in an immiscible Fe-Cu system
Authors: Huang L. J. , Liu B. X.
Published: July 2002

Spontaneous vitrification was observed in the equilibrium immiscible Fe-Cu system. The metastable phase before vitrification was an icosahedral incommensurate phase which was formed by an ion beam mixing of Fe-Cu multilayer films at room temperature and subsequent high-temperature thermal annealing. The electrical and magnetic properties of the icosahedral phase are also reported, and the relation with spontaneous vitrification is discussed.
Emission spectroscopy during excimer laser ablation of graphite
Authors: Chen Xiangli , Mazumder Jyoti
Published: July 2002

Emission spectrum of the laser-induced plasma plume is obtained during KrF excimer laser ablation of graphite in argon and hydrogen gas mixture for deposition of diamond-like films. Bands of C2 and CN molecules dominate the spectrum while weak CI, CII, and Hα lines are also observed. From the emission intensities, molecular vibrational temperature is calculated to be (12–15)×103 K, and concentrations are estimated to be N(C2)=5×1014 cm−3 and N(CN)=2×1014 cm−3.
Temperature dependence of threshold of strained quantum well lasers
Authors: Dutta N. K. , Lopata J. , Sivco D. L. , Cho A. Y.
Published: July 2002

The temperature dependence of threshold current of strained quantum well lasers is analyzed both experimentally and theoretically. The measurements are performed on ridge waveguide In0.2Ga0.8As/GaAs multiquantum well lasers emitting near 1 μm. The carrier densities at threshold of these lasers are measured using very short current pulse injection. A simplified calculation of the radiative, nonradiative recombination rates and the relationship between gain and carrier density in strained quantum well lasers is described. The results of the calculation are compared with experimental results.
Excitonic absorption saturation in ternary alloy AlxGa1−xAs/AlAs multiple-quantum-well structures
Authors: Dabbicco M. , Cingolani R. , Ferrara M. , Ploog K. , Fisher A.
Published: July 2002

The bleaching of the n=1 and n=2 heavy-hole exciton absorption has been observed at room temperature in ternary alloy Al0.37Ga0.63As/AlAs multiple-quantum-well structures by nanoseconds pump-and-probe spectroscopy. The relative variation of the absorption coefficient [(−Δα)/α0] are about 15% and 8%, respectively. The nonlinear absorption coefficient (α2) and the nonlinear absorption cross section has been deduced. The value of the saturation density deduced from our spectra is in good agreement with the theoretical predictions. The influence of the staggered band alignment on the observed process is also discussed.
Are amorphous ferromagnets with λS=0 magnetostrictive on a local scale?
Authors: Fähnle Manfred , Furthmüller Jürgen , Pawellek Reiner , Beuerle Traude
Published: July 2002

Considering the temperature dependence of the saturation magnetostriction constant λS(T) of near-zero magnetostrictive amorphous ferromagnets, we give arguments for the conjecture that these materials are magnetostrictive on a local scale.
Coupling between barrier and quantum well energy states in a multiple quantum well optical amplifier
Authors: Tessler N. , Nagar R. , Abraham D. , Eisenstein G. , Koren U. , Raybon G.
Published: July 2002

We describe the interaction between carriers in three-dimensional barrier and confinement regions and two-dimensional quantum well regions of a 1.5 μm multiple quantum well optical amplifier. We present a model and measurements of the spontaneous emission and gain spectra dependence on an external optical pump signal.
Heavily Si-doped GaAs grown by low-pressure metalorganic chemical vapor deposition using tertiarybutylarsine and silane
Authors: Chichibu S. , Iwai A. , Matsumoto S. , Higuchi H.
Published: July 2002

Heavy Si doping was studied for low-pressure metalorganic chemical vapor deposition of GaAs by using tertiarybutylarsine (tBAs) as a group-V source and silane (SiH4) as a doping source gas. The Si doping efficiency was higher by one order of magnitude when tBAs was used instead of arsine (AsH3). The maximum electron concentration was 9.0×1018 cm−3, which is slightly higher than that obtained for AsH3 (5.9×1018 cm−3). The slight increase of the maximum concentration is considered to be due to a reduction of the carrier compensating center generated in high SiH4 partial pressure conditions. Generation of the electrical compensating center is assigned to be related with the carbon incorporation from alkylsilanes during growth.
Study of a plasma-filled X-band backward wave oscillator
Authors: Zhai X. , Garate E. , Prohaska R. , Benford Gregory
Published: July 2002

We present experimental studies of a plasma-filled X-band backward wave oscillator (BWO). Depending on the background gas pressure, microwave frequency upshifts of up to 1 GHz appeared along with an enhancement of a factor of 7 in the total microwave power emission. The bandwidth of the microwave emission increased from ≤0.5 to 2 GHz when the BWO was working at the rf power enhancement pressure region. The rf power enhancement appeared over a much wider pressure range in a high beam current case (10–100 mT for 3 kA) as compared to a lower beam case (80–115 mT for 1.6 kA). The plasma-filled BWO has higher power output compared to the vacuum BWO over a broader region of magnetic guide field strength.
Point defect injection into silicon due to low-temperature surface modifications
Authors: Christensen Carsten , Petersen Jon Wulff , Larsen Arne Nylandsted
Published: July 2002

Deep level transient spectroscopy has been applied to study the appearance of phosphorus-vacancy pairs in n-type silicon following different low-temperature surface modifications. It is established that at most 107 cm−2 vacancy is injected into the bulk of the silicon substrate during Pd2Si silicide formation. On the other hand, phosphorus-vacancies pairs are observed after electron irradiation, low energy ion bombardment, and electron gun evaporation of metal films.
High repetition rate picosecond laser system at 1983 nm
Authors: Tomov I. V. , Anderson T. , Rentzepis P. M.
Published: July 2002

An efficient scheme to generate picosecond seed pulses at 193 nm for amplification in ArF is described. The amplifier system operates at a repetition rate of 300 Hz providing average output power of 750 mW and pulse duration below 10 ps.
Effect of axial strain on the critical current of Ag-sheathed Bi-based superconductors in magnetic fields up to 25 T
Authors: Ekin J. W. , Finnemore D. K. , Li Qiang , Tenbrink J. , Carter W.
Published: July 2002

The irreversible strain limit εirrev for the onset of permanent axial strain damage to Ag-sheathed Bi2Sr2Ca1Cu2O8+x and Bi2Sr2Ca2Cu3O10+x superconductors has been measured to be in the range of 0.2%–0.35%. This strain damage onset is about an order of magnitude higher than for bulk sintered Y-, Bi-, or Tl-based superconductors and is approaching practical values for magnet design. The measurements show that the value of εirrev is not dependent on magnetic field, nor does the critical current depend on strain below εirrev at least up to 25 T at 4.2 K. Both of these factors indicate that the observed strain effect in Ag-sheathed Bi-based superconductors is not intrinsic to the superconductor material. Rather, the effect is extrinsic and arises from superconductor fracture. Thus, the damage onset is amenable to further enhancement. Indeed, the data suggest that subdividing the superconductor into fine filaments or adding Ag to the superconductor powder prior to processing significantly enhances the damage threshold εirrev to above 0.6%.
Silicon-fluorine bonding and fluorine profiling in SiO2 films grown by NF3-enhanced oxidation
Authors: Kouvatsos D. , McCluskey F. P. , Jaccodine R. J. , Stevie F. A.
Published: July 2002

The incorporation and chemical bonding of fluorine introduced in SiO2 thin films by NF3-enhanced oxidation of silicon has been studied by means of x-ray photoelectron spectroscopy and secondary ion mass spectrometry depth profiling. Fluorine bonding in the oxide network is observed, indicated to occur in the area of the oxidizing interface and resulting in depth profiles which reflect the manner of the exposure of the growing oxide to the NF3 fluorine source during oxidation.
Electroabsorption modulator based on Wannier–Stark localization with 20 GHz/V efficiency
Authors: Devaux Fabrice , Bigan Erwan , Allovon Michel , Harmand Jean-Christophe , Huet Frederic , Carré Madeleine , Landreau Jean
Published: July 2002

We report on a ridge-waveguide modulator based on Wannier–Stark localization in an InGaAs/InAlAs superlattice. Anisotropic absorption is measured and efficient modulation is obtained in the low-field domain and in the high-field domain with TE-polarized light. The device exhibits outstanding HF characteristics: in terms of bandwidth-to-drive-voltage ratio, we find that the Wannier–Stark localization is far more efficient than the quantum Stark effect.
Epitaxial bcc FexCo1−x alloy films on ZnSe(001)
Authors: Gutierrez C. J. , Krebs J. J. , Prinz G. A.
Published: July 2002

Molecular beam epitaxy has been used to fabricate high-quality bcc FexCo1−x(001) ferromagnetic alloy films on ZnSe-epilayered GaAs substrates spanning both the thermodynamically allowed bcc regime (0.25<x≤1) and the epitaxy-extended metastable bcc regime (0≤x≤0.25). Film growth was monitored by reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy, and the concentration-dependent magnetic properties of these alloy films were characterized by ferromagnetic resonance and vibrating sample magnetometry. It was observed that the RHEED characteristics of the alloy films generally are superior to those of similarly grown pure Fe(001) films.
Laser action from Mn5+ in Ba3(VO4)2
Authors: Merkle Larry D. , Pinto Albert , Verdún Horacio R. , McIntosh Bruce
Published: July 2002

We report the first observation, to our knowledge, of three-level laser oscillator operation in a crystal activated with Mn5+. The material is Mn:Ba3(VO4)2 which exhibited laser oscillation at room temperature under pulsed 592 nm excitation. The laser emission occurs at 1181 nm with a threshold of 0.3 J/cm2. Spectroscopy indicates that this material operates as a three-level system on the 1E to 3A2 transition of the Mn5+ ion with tetrahedral coordination. The strong, broad absorption bands and 0.43 ms room-temperature lifetime make this system very promising for flash lamp AlxGa1−xAs diode pumping.
Reactive chemical intermediates in metalorganic chemical vapor deposition of GaAs
Authors: Killeen K. P.
Published: July 2002

Reactive chemical gas-phase intermediate species important in the metalorganic chemical vapor deposition growth process of GaAs have been identified for the first time using in situ ultraviolet absorption spectroscopy. Spectral features from Ga, GaH, and GaCH3 were observed during thermal decomposition of trimethylgallium (TMGa) in hydrogen gas. Evidence for free radical reactions involving CH3 and H in the pyrolysis of TMGa is presented. The addition of arsine to the mixture is found to change the reaction pathways as evident from the production of AsH2 and the disappearance of Ga and GaH. Gas-phase decomposition of the metalorganic species in hydrogen can produce gallium under the conditions of high pressure atomic layer epitaxy.
Erratum: ‘‘Multiple quantum well light modulators for the 1.06 μm range on InP substrates: InxGa1−xAsyP1−y/InP, InAsyP1−y/InP, and coherently strained InAsyP1−y/InxGa1−xP’’ [Appl. Phys. Lett. 60, 2846 (1992)]
Authors: Woodward T. K. , Chiu T.-H. , Sizer Theodore
Published: July 2002

The last sentence in the paragraph at the top of the second column of the second page of the article should read: ‘‘Since previously reported samples like B have been described with sharper excitonic features (HWHM of 6 meV at 300 K and 2 meV at 10 K) it is reasonable to expect that sample C could be further improved.4’’
Erratum: ‘‘High repetition rate picosecond laser system at 1983 nm’’ [Appl. Phys. Lett. 61, 1157 (1992)]
Authors: Tomov I. V. , Anderson T. , Rentzepis P. M.
Published: July 2002

The title of this letter was incorrectly printed. The title should read ‘‘High repetition rate picosecond laser system at 193 nm.’’
Absolute copper atom density determination in laser-ablated copper plasmas using hook spectroscopy
Authors: Sappey Andrew D. , Gamble Thomas K. , Zerkle David K.
Published: July 2002

Hook spectroscopy has been implemented to measure the absolute density of atomic species in a laser-ablated plasma plume. We use the hook method to determine the density of copper atoms produced by ablation of a copper target in 25 Torr of helium at power densities of ∼1 GW/cm2. The measured copper densities when ablating into 25 Torr of helium backing gas range from 1.5×1015 cm−3 at a delay of 200 μs to 4.4×1013 cm−3 at 5 ms delay. This dramatic decrease in density is due to condensation of the metal vapor to form fine particulate.
Current-voltage characteristics and interface state density of GaAs Schottky barrier
Authors: Maeda Keiji , Ikoma Hideaki , Sato Kenji , Ishida Toshiki
Published: July 2002

A density distribution of the interface states in GaAs Schottky barrier was derived for the first time from observed nonideal I-V characteristics of a GaAs Schottky barrier with an oxidized interface. With increasing forward bias voltage, the ideality factor increases and then decreases after passing a maximum. Fermi level of the interface states shifts with the applied bias in the interfacial layer model adopted for the analysis. The obtained energy level of the interface states is in agreement with a previously reported value. However, the absolute magnitude of the state density is quite small compared with that obtained from the weak dependence of the barrier height on metal work functions. Implications of this result are discussed.
Measurement of second-harmonic generation from colored powders
Authors: Kiguchi M. , Kato M. , Taniguchi Y.
Published: July 2002

The second-harmonic generation with evanescent wave technique was used to measure the efficiency of second-harmonic generation of an organic colored powder that absorbs the second-harmonic wave, and it was compared to the electro-optic coefficient. The refractive index of the sample at the second-harmonic frequency is complex. The effective refractive index was obtained by measuring reflectivity at the interface between the sample and the prism. This technique is potentially useful for surveying electro-optic materials.
Magnetoresistance in Au-Co-B heterogeneous alloys
Authors: von Helmolt R. , Wecker J. , Samwer K.
Published: July 2002

Au-Co and Au-Co-B alloys have been prepared by rapid solidification, followed by heat treatment. The precipitation of the ferromagnetic phases Co and Co2B in the Au matrix phase has been observed during annealing. At room temperature, both magnetization and magnetoresistance are determined by the superparamagnetic behavior of the ferromagnetic particles. The magnetoresistance is believed to have the same origin as that in multilayers and granular films. Both Co particles and the precipitates of the Co2B intermetallic phase give rise to a high magnetoresistance. The magnetoresistance effect was less than 1% in the as-quenched samples and increased to about 3% after an appropriate heat treatment.
Selective trilayer deposition process for fabricating Nb/Al-AlOx/Nb Josephson tunnel junctions
Authors: Monaco R. , Oliva A.
Published: July 2002

High quality Nb/Al-AlOx/Nb Josephson tunnel junctions have been fabricated using a novel process named the selective trilayer deposition process. The junction is formed on a patterned Nb underlayer through the lift-off deposition of a Nb/Al-AlOx/Nb trilayer. Anodization then provides the insulation between the underlayer and the wiring layer. We show that this easy and simple process is particularly advantageous for the fabrication of many vertically stacked tunnel junctions.
Kinetically controlled order/disorder structure in GaInP
Authors: Su L. C. , Ho I. H. , Stringfellow G. B.
Published: July 2002

A Ga0.52In0.48P order/disorder heterostructure having a band-gap energy difference exceeding 160 meV has been grown by organometallic vapor phase epitaxy. The two layers were grown on a nominally (001)-oriented GaAs substrate misoriented by 3° toward the [1̄10] direction in the lattice. The disordered layer was grown first, at a temperature of 740 °C. The temperature was then reduced to 620 °C for the growth of the second, highly ordered, layer. X-ray diffraction shows that the two layers have the same composition and are both lattice matched to the GaAs substrate. Transmission electron diffraction patterns indicate that the first layer is completely disordered and that the second layer is highly ordered with only one variant. A low density of antiphase boundaries is observed in the dark field transmission electron microscope image of the top (ordered) layer. High resolution images demonstrate that the interface is abrupt with no dislocations or other defects. Photoluminescence measured at 10 K shows two sharp and distinct peaks at 1.998 and 1.835 eV for high excitation intensities. The peak separation is even larger at lower excitation intensities. The two peaks come from the disordered and ordered materials, respectively. The peak separation represents the largest energy difference between ordered and disordered material reported to date. This large energy difference, much larger than kT at room temperature, may make such heterostructures useful for photonic devices such as light emitting diodes and lasers.
Advances in laser fluorescence scattering with Balmer series dye lasers
Authors: Evans D. A. , Forrest M. J. , Nicholson M. G. , Burgess D. D. , Carolan P. G. , Gohil P.
Published: July 2002

The spatial distribution of neutral deuterium has been determined in a reversed field pinch by fluorescence scattering. The first series of measurements, with a resolution of 4 cm were made with the laser tuned to the Dα, n=2−3(6561 Å) transition. The second set of measurements, with both 4 and 2 cm resolution were performed with the laser tuned to the Dβn=2−4(4861 Å) wavelength. The improvement in signal to noise obtained was substantial, being increased by a factor of ≂2.5 in general. This is believed to be the first such measurement at this wavelength. The advantages of using this transition are such that this technique can be extended to measure the electron density near the plasma edge.
100-cm−1 scan range single-mode dye laser
Authors: Uehara Kiyoji , Sasada Hiroyuki , Ukaji Nobuyoshi , Kasuya Takahiro
Published: July 2002

A cw dye laser was automatically tuned as wide as 100 cm−1 with a very simple control system while retaining a narrow spectral width of 15 MHz. This wide scanning was accomplished by repetitive 5-cm−1 sweeps of both the laser cavity and an internal étalon along with a continuous tuning of a birefringent filter. Mode jumps were prevented by locking the cavity to the internal étalon by a novel type of integrating servoamplifier which has an auto-reset function. This scan system proved very useful for a wide-ranged spectral measurement of the Doppler-limited resolution. The jumpless scanning with a constant rotational speed of the birefringent filter is extendable up to 230 cm−1 at around 1.7×104 cm−1.
Automated ac galvanomagnetic measurement system
Authors: Szofran F. R. , Espy P. N.
Published: July 2002

An automated, ac galvanomagnetic measurement system is described. Hall or van der Pauw measurements in the temperature range 10–300 K can be made at a preselected magnetic field without operator attendance. Procedures to validate sample installation and correct operation of other system functions, such as magnetic field and thermometry, are included. Advantages of ac measurements are discussed.
Simple numerical analysis of null-point calorimeter data
Authors: Wyeth N. Convers
Published: July 2002

Null-point calorimeters provide the equivalent surface temperature data for a slab exposed to a time-varying flux. A simple method to calculate the absorbed flux as a function of time using such temperature versus time data is presented. The method involves numerical evaluation of a convolution integral of the first time derivative of the temperature and a function defined by an infinite sum. The temperature derivative is calculated using a least-squares-fitting algorithm, and the infinite sum using a close analytic approximation. The method is applied to two sets of actual null-point calorimeter data, and the calculated flux is in excellent agreement with data obtained by other means.
High-frequency time-domain dielectric spectrometer for the determination of water in polymer coatings on metal substrates
Authors: Eadline Douglas J. , Leidheiser Henry
Published: July 2002

High-frequency dielectric measurements on coatings for corrosion control are accomplished using a capacitor sample cell in conjunction with a dielectric spectrometer. Dielectric measurements at high frequencies provide information about water in coatings. The spectrometer is a time-domain device whereby the capacitor cell is pulsed and the response noted. Frequency data from 107 to 109 Hz are obtained from the time data using the Fourier transform. A new lumped capacitor sample cell designed for organic coatings is presented. High speed pulse generation, transmission, and capture are accomplished with a sampling oscilloscope system. A circuit is provided that interfaces the sampling oscilloscope to a small data-acquisition computer. The time data recorded with the data collection computer are sent to a large mainframe computer for mathematical processing. The function of the complete spectrometer system is described with attention given to the time referencing step and the Fourier transform technique. The spectrometer is tested using both a Teflon and a polyvinyl acetate–water system. Data for both systems are provided. An enhancement of the polyvinyl acetate β mechanism with addition of water, previously measured at lower frequencies and temperatures, is now observed at room temperature.
Flip-chip bonding with solder dipping
Authors: Brady M. J. , Davidson A.
Published: July 2002

We report a simple technique for making flip-chip contacts. The equipment required, in addition to a small-scale photoresist clean room, is a beaker of molten solder.
Heterodyne interferometer of coaxial CO2 and He–Ne lasers for plasma density measurements
Authors: Takahashi Hidemi , Kimura Minoru , Sano Reiji , Nagayama Yoshio , Miyamoto Kenro
Published: July 2002

An interferometer using coaxial CO2 and He–Ne lasers has been developed for electron density measurements in the reversed field pinch plasma. The interferometer uses the phase modulating heterodyne detection of 60 MHz. The CO2 laser interferometer is free from the mechanical vibrations due to the reduction of the vibrations by the air springs and the compensation of the vibrations by the He–Ne laser interferometer. The electron density measurement during a long-time discharge of 50 ms without the disturbance by the vibrations is achievable. The resolution is less than 1/100 fringe of the CO2 laser interferometer, therefore the electron line density as small as 1.1×1014 electrons/cm2 is detectable.
Status of the Kansas State University superconducting linac project
Authors: Gray Tom J.
Published: July 2002

Funding for the construction of the superconducting linac at Kansas State University was approved by the Department of Energy on May 15, 1985. The project is funded out of the Division of Chemical Sciences, USDOE. Initial design and staff technical training was initiated during 1984–85 with laboratory personnel working at both Florida State University and Argonne National Laboratory. The linac under construction is based upon the Nb split-ring resonator technology developed at Argonne National Laboratory for ATLAS. The linac at Kansas State University will have 14 superconducting resonators with nine low-β (β=0.06) and five high-β (β=0.105) units operating at 97 MHz. Work has progressed on both of the single-resonator cryostats for time bunching and energy rebunching, respectively, with the major cryostat components presently under construction by C. E. Raymond Enterprise Manufacturing, a division of Combustion Engineering, with scheduled delivery of the single resonator cryostat vacuum housings, LN2-cooled heat shields, and LHe Dewars on January 17, 1986. Orders for all Nb-clad Cu resonators have been placed with Argonne National Laboratory and two low-β units are currently under construction. Requests for quotations for a 300-W LHe refrigerator (expandable to 500 W) 1000-l storage Dewar and LHe distribution system have been issued. The building addition which includes a new accelerator/experimental hall (∼6000 ft2 basement structure) and ground-level laboratory support space including additional experimental setup space, additional machine shop space, and mechanical equipment space, is currently under construction with a completion date scheduled for May 1986. Additional personnel training on LHe refrigeration systems is scheduled for January 1986, at the Texas Accelerator Center and at Florida State University.
Frequency tripling into the 720–1025-Å region with pulsed free jets
Authors: Page Ralph H. , Larkin Robert J. , Kung A. H. , Shen Y. R. , Lee Y. T.
Published: July 2002

We have developed a coherent source of XUV light, which is continuously tunable between 904 and 1024 Å, and line tunable to 720 Å. It employs the technique of frequency tripling in a pulsed free jet of gas, and requires a single tunable laser system. Spectra of the relative XUV output vs wavelength in the 904–1024-Å range are presented for the tripling gases Ar, Kr, Xe, CO, and N2. Also listed are relative outputs obtained by tripling at resonantly enhanced lines between 720 and 900 Å in Kr, Xe, and CO. Possible improvements to the source are discussed, and examples of its application are given.
Optical fiber heterodyne interferometer probe free from external disturbance
Authors: Nakatani Noboru , Izumi Takao , Asano Shin , Yamada Tomoharu , Sakabe Toshiya
Published: July 2002

A fiber heterodyne interferometer probe free from external disturbance, which can measure small displacement of an object as a pressure transducer or a vibrational object, is described. The phase fluctuation in the fiber due to external disturbance is excluded using a reference beat signal of light beams from a reflection mirror on a graded index rod lens. A graded index-type multimode fiber connected to one end of a single-mode fiber by arc fusion splicing is used to improve acceptance of the light. The characteristics of the fiber probe are also described.
Removal of phototubes from Pb–glass detectors
Authors: Alburger D. E.
Published: July 2002

A simple procedure is described for removing faulty photomultiplier tubes from Pb–glass detectors by means of heated chloroform.
Development of the vibrational time-delay technique and the study of stress/strain coupled diffusion in polymers
Authors: Chipalkatti Makarand H. , Farris Richard J. , Hutchinson John M.
Published: July 2002

A technique has been developed to measure the linear mass density of fibers and ribbons, and adapted to the study of stress/strain coupled diffusion in polymeric materials. The technique overcomes the limitations of sensitivity and range, typical of traditional diffusion measurement techniques, and can be used for a wide range of fiber densities. It is also possible to monitor stress or strain within the fiber while measuring the change in mass, without requiring the fiber to be at equilibrium or interrupting the experiment. Estimates of material property changes, as exemplified by tensile modulus changes, can also be made during the course of the experiment. The mass per unit length, at any given time, of polymer fibers or ribbons under known stresses and strains can be determined by this technique. From this it is possible to estimate the gain or loss in weight in the sample due to permeants diffusion. Some preliminary result of constant strain and constant stress experiments on ribbons of polycarbonate, polyimide, and precured epoxy, and KevlarR monofilaments, are discussed and the scope and resolution of the apparatus are indicated.
Novel optical device for simultaneous measurements of Raman and absorption spectra: Application to photolabile reaction intermediates of hemeproteins
Authors: Ogura Takashi , Kitagawa Teizo
Published: July 2002

Resonance Raman studies on transient molecules have raised a problem about characterization of a photolabile species. Therefore, in order to observe the Raman and absorption spectra of the same spatial region of the sample at the same time, we have constructed a novel device and applied it successfully to monitor the transient species involved in an enzymic reaction of horseradish peroxidase and in photodissociation of the carbon monoxide adduct of hemoglobin.
High-resolution optical probing by means of long laser pulses
Authors: Bulloni M. , De Silvestri S. , Yupu Liu , Magni V. , Laporta P. , Zaraga F.
Published: July 2002

The purpose of this article is to discuss techniques and present data related to the performance of optical probing of the thickness of thin transparent materials and of the dimensions of mechanical components to a few-microns resolution. The experimental apparatus for high-resolution optical probing is based on nonlinear autocorrelation of partially mode-locked laser pulses. Using the presence of the coherent spike in the autocorrelation trace as a marker, a resolution of the order of a few microns is obtained independently of the length of the pulse. The experimental apparatus consists of a rhodamine 6G dye laser synchronously pumped by the second harmonic of a cw mode-locked Nd:YAG laser. The picosecond pulse train is sent to an optical autocorrelator similar to that used to measure pulse duration. To show the precision and versatility of the technique, applications are presented to the measurement of the thickness of transparent materials (plastic and liquid films), and to the measurement of dimensions of mechanical components.
Excitation rates for plasma impurity measurements by x-ray diagnostics
Authors: Hill K. W. , Bitter M. , von Goeler S. , Hsuan H. , Hulse R. , Johnson L. C. , Lasalle P. , McGuire K. S. , Murphy A. , Stevens J. E. , Wieland R. M.
Published: July 2002

Measurement of intrinsic and injected impurity concentrations and transport in tokamak plasmas by x-ray pulse-height analysis (PHA) and x-ray imaging (XI) diode arrays requires reliable excitation rates for a number of charge states of a range of elements (Al, Se, Ti, Cr, Fe, Ni, Ge, etc.). Previous PHA measurements at Princeton have relied on a coronal-equilibrium average of excitation rates for iron, and a prescription for scaling the average rate to nearby elements. For improved accuracy in PHA measurements (using the MIST impurity equilibrium and transport code) and for interpretation of XI data (using an x-ray simulation code), rates for excitation of dominant charge states by electron impact, dielectronic recombination, and radiative recombination have been calculated from available atomic data and parametrized as a function of atomic number (Z=10–42) and electron temperature (Te =0.1–10.0 keV).