bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow‐Cytometric Determination of the Respiratory Activity in Growing Saccharomyces cerevisiae Populations
Authors: Porro Danilo , Smeraldi Carla , Martegani Enzo , Ranzi Bianca Maria , Alberghina Lilia
Published: March 2005

Flow cytometry allows one to measure relevant physical or chemical properties on a single cell, yielding the distribution of these properties in the cell population. Typically, flow cytometry has been used to determine DNA or protein distributions, but it could be extended to the determination of other relevant parameters, such as intracellular pH, membrane potential, intracellular Ca2+ concentration, mitochondrial activity, etc. In the present work, we used flow cytometry to determine the respiratory activity in intact Saccharomyces cerevisiae cells after staining with the cationic lipophilic dye rhodamine 123 (Rhl23). We found a good correlation between the Rh123 fluorescence distribution in yeast populations and the degree of respiratory activity, which can be varied by changing the carbon source used for yeast growth. In addition, we developed a vital staining procedure which allows one to measure fast changes in the respiratory activity. We used this technique to follow the kinetics of glucose repression and to measure the apparent Km for the substrate. Our results demonstrate that flow cytometry is a fast and very sensitive method to evaluate the respiratory activity in yeast cells and is also suitable for the determination of rapid changes in yeast metabolism. Biotech‐nological implications of this study are also discussed.
Penicillin‐G Enhanced Production of Thuringiensin by Bacillus thuringiensis sp. darmstadiensis
Authors: Tzeng Yew ‐Min , Young Yu‐Hsiang
Published: March 2005

The effect of penicillin‐G on the production of the potential microbial insecticide thuringiensin by Bacillus thuringiensis sp. darmstadiensis was studied. Shake flask and 3‐L jar fermentor studies showed that the addition of 360 units/mL penicillin‐G at 9 h, when the fermentable sugar in the medium was about to be mostly consumed, improved thuringiensin production by more than 1‐fold relative to the control. The dosage of 360 units/mL penicillin‐G had only a modest effect on the growth of the microorganism. However, cell growth was inhibited at higher dosages of the antibiotic. Since penicillin‐G could interfere with cell wall synthesis, which facilitated the release of thuringiensin, a high thuringiensin productivity of 2600 mg/L was attained in this study, which is about 2–10‐fold higher than those values reported in the literature.
Enhancement of Secondary Metabolite Production by Immobilized Gossypium arboreum Cells
Authors: Choi Hojoon J. , Tao Bernard Y. , Okos Martin R.
Published: March 2005

A novel reactor with simultaneous use of plant cell immobilization, permeabilization, and elicitation was designed to enhance the productivity of secondary metabolites and to overcome limitations of plant cell culture, such as slow metabolic rate, low product yield, and sensitivity to shear stresses. Production of gossypol, an antifungal agent, from Gossypium arboreum was selected as a model system. The effects of immobilization, permeabilization, and elicitation on gossypol production were investigated in free suspension culture, immobilized plant cell reactor with recycled batch operation, and bioreactor with continuous operation. G. arboreum cells were effectively immobilized on a cotton matrix by entrapment with a spirally wound configuration. Permeabilization of immobilized cells provided a tool for a continuous process increasing the release of gossypol by 30%, while the elicitation technique played a major role to enhance productivity by more than 8‐fold. In comparisons of productivity, continuous operation and combined treatment gave productivity over 20‐fold higher than batch culture. Simultaneous use of immobilization, permeabilization, and elicitation was possible in continuous operation with an immobilized plant cell reactor.
Co‐overexpression of prlF Increases Cell Viability and Enzyme Yields in Recombinant Escherichia coli Expressing Bacillus stearothermophilus α‐Amylase
Authors: Minas Wolfgang , Bailey James E.
Published: March 2005

The effects on cloned amylase production of co‐overexpression of prlF, a gene that appears to interact with the sec protein export machinery in Escherichia coli, was investigated by comparing three expression systems: (i) a high copy number plasmid with the Bacillus stearothermophilus α‐amylase gene (amyS) cloned with its promoter downstream of the lac promoter; (ii) a pBR322‐based vector with amyS under control of the indigenous Bacillus promoter; and (iii) a temperature‐inducible vector with runaway replicon and λpL promoter‐controlled gene expression. In addition, protease mutants (lon−) of E. coli C600 were used to evaluate the influence of the Lon protease on net enzyme formation and activity degradation during batch fermentations. Our results show that α‐amylase synthesis occurred during exponential growth and ceased in the stationary phase. While strong promoters on high copy number plasmids severely impaired cell viability, resulting in culture lysis at mid‐log phase, co‐overexpression of prlF greatly improved cell viability, as well as the yield and specific production of α‐amylase for the expression constructs considered. lon deficiency slightly increased amylase stability during the late stationary phase. However, the specific productivity of ion− strains was only about 40–60% that of the isogenic E. coli C600 equivalent.
Retention Behavior of Amino Acids Using Immobilized Ag(I) Chromatography
Authors: Kim Dong‐Hoon , Garcia Antonio A.
Published: March 2005

A mathematical description of retention times for several amino acids on a polyacrylamide resin containing immobilized Ag(I) is presented in this paper. Immobilization of Ag(I) ions onto a chromatography support allows for the expansion of immobilized metal affinity chromatography (IMAC) to include soft acid/soft base interactions. For the retention of methionine, histidine, and tryptophan, a mathematical model is presented that rationalizes the retention behavior of these amino acids on a Ag(I) column as a function of silver ion loading and pH. The pH effect is important in that methionine is retained longer than histidine at pH values below 5, while at pH 7 histidine is retained longer than methionine. The effects of nonspecific interactions with the modified polymer, electrostatic interactions, and soft acid/soft base interactions are also taken into account by the model. This approach may also be useful for modeling the retention times of amino acids on other types of IMAC columns.
An Energetically Structured Model of Mammalian Cell Metabolism. 1. Model Development and Application to Steady‐State Hybridoma Cell Growth in Continuous Culture
Authors: Dimasi Don , Swartz Randall W.
Published: March 2005

Incomplete understanding of mammalian cell culture kinetics hinders the ability of the biochemical engineer or biologist to design and control mammalian cell culture systems and to develop operating strategies. To address this problem, a mechanistic, structured mathematical model has been developed to simulate mammalian cell culture kinetics under a variety of bioreactor operating conditions. An important feature of in vitro mammalian cell metabolism in conventional cell culture media is the partial substitutability of the substrates glucose and glutamine for provision of energy in the cell. The utilization of glucose and glutamine by cells can therefore vary substantially, and these changes can profoundly affect the culture behavior. The model developed here specifically addresses the dynamics of substrate consumption and energy metabolism in mammalian cell culture. This energetically structured (ES) model is also distinguished by the consideration of changes in the specific cell mass with specific growth rate and the consideration of essential amino acids as potentially growth rate limiting. The model is applied here to simulate literature data on the growth and metabolism of a murine hybridoma in continuous culture.
High‐speed telescopic imaging of sprites
Authors: Marshall R. A. , Inan U. S.
Published: March 2005

Telescopic video observations of sprites at high frame rates show very complex structures in both space and time, including bead and streamer‐like formations and propagation. Observed streamers rarely persist for more than 1–2 ms, while observed beads persist up to tens of ms and do not appear to propagate in this data set. Additionally, images show that streamer‐like channels often contain many bead‐like structures. While the time resolution cannot directly observe propagation, images show that the so‐called “streamers” presented here do seem to exhibit signs of propagation. These results are compared to previous measurements and discussed in the context of streamer modeling and laboratory streamers.
Local intermittency measure analysis of AE index: The directly driven and unloading component
Authors: Consolini Giuseppe , De Michelis Paola
Published: March 2005

The Auroral Electrojet (AE) index, introduced to track the global high‐latitude geomagnetic activity, is representative of two different processes (Kamide and Kokubun, 1996): the solar‐wind directly driven convection enhancement, and the impulsive unloading process. Here, we present a new technique, based on the Local Intermittency Measure analysis, to separate these two contributions in the AE index. In detail, we applied this approach to extract the coherent intermittent structures that are linked with the impulsive unloading process.
Thermocline mixing in summer stratified continental shelf seas
Authors: Rippeth Tom P. , Palmer Matthew R. , Simpson John H. , Fisher Neil R. , Sharples Jonathan
Published: March 2005

A key process in the shelf sea pumping of CO2 to the open ocean is vertical mixing in the summer stratified zones of continental shelf seas. Here, we present measurements of profiles of the rate of dissipation of turbulent kinetic energy (ɛ), from which vertical mixing is inferred, for several locations in the summer stratified zones of the NW European shelf seas. At both sites we find significant thermocline mixing, with ∼20% of the observed turbulent dissipation taking place within the thermocline. We then present evidence to demonstrate that the thermocline mixing is a result of shear instability within the thermocline. This is contrary to the conventional view that vertical mixing in shelf seas is largely driven by boundary shear stresses.
A reconstructed Siberian High index since A.D. 1599 from Eurasian and North American tree rings
Authors: D'Arrigo Rosanne , Jacoby Gordon , Wilson Rob , Panagiotopoulos Fotis
Published: March 2005

The long‐term variability of the Siberian High, the dominant Northern Hemisphere anticyclone during winter, is largely unknown. To investigate how this feature varied prior to the instrumental record, we present a reconstruction of a Dec–Feb Siberian High (SH) index based on Eurasian and North American tree rings. Spanning 1599–1980, it provides information on SH variability over the past four centuries. A decline in the instrumental SH index since the late 1970s, related to Eurasian warming, is the most striking feature over the past four hundred years. It is associated with a highly significant (p < 0.0001) step change in 1989. Significant ∼3–4 yr spectral peaks in the reconstruction fall within the range of variability of the East Asian winter monsoon (which has also declined recently) and lend further support to proposed relationships between these large‐scale features of the climate system.
Trends evolution of ozone between 1980 and 2000 at midlatitudes over the Southern Hemisphere: Decadal differences in trends
Authors: Malanca Fabio E. , Canziani Pablo O. , Argüello Gustavo A.
Published: March 2005

The variability of atmospheric midlatitudinal ozone between 1980 and 2000 over the Southern Hemisphere is discussed. The distribution of ozone and ozone change during the seasonal cycle is discussed using Total Ozone Mapping Spectrometer Nimbus and Earth Probe data binned at 72 (30° longitude by 5° latitude) bins, between 60° and 30°S. Rather than using a standard trend approach, the annual mean time series for each bin were fitted with a cubic polynomial. The results show that in the zonal mean sense there is a sizable, latitude‐dependent slowdown of the ozone loss from the early 1990s onward, but when individual bins are considered, significant longitudinal patterns of ozone change appear, with both positive (enhancement) and negative (depletion) changes in total ozone. Thus regional evolution remains important as an indicator both of chemical depletion evolution and the relation with climate. Such longitudinal behavior is limited in the subtropics and grows toward the subpolar edge of the sampled region. For example, a large decrease was observed over southern South America in the 1980s, but during the 1990s there was only a limited change. The analysis for January, June, and October over the 20‐year period shows changes in the evolution along the year, both in time and space. Furthermore, such seasonally dependent changes reach a peak in October, as would be expected. The October pattern of interannual variability could be linked to Southern Annular Mode, though there probably are some other processes driving it.
The state of the filament
Authors: Aguda Adeleke H. , Burtnick Leslie D. , Robinson Robert C.
Published: March 2005

Movement is a defining characteristic of life. Macroscopic motion is driven by the dynamic interactions of myosin with actin filaments in muscle. Directed polymerization of actin behind the advancing membrane of a eukaryotic cell generates microscopic movement. Despite the fundamental importance of actin in these processes, the structure of the actin filament remains unknown. The Holmes model of the actin filament was published 15 years ago, and although it has been widely accepted, no high‐resolution structural data have yet confirmed its veracity. Here, we review the implications of recently determined structures of F‐actin‐binding proteins for the structure of the actin filament and suggest a series of in silico tests for actin‐filament models. We also review the significance of these structures for the arp2/3‐mediated branched filament.
A GaAs1−xPx NEGATIVE-RESISTANCE LIGHT-EMITTING DIODE
Authors: Gerhard G. C. , Jensen H. A.
Published: March 2005

The electrical and optical properties of double-injection diodes fabricated from GaAs1−xPx are described. Under forward-biased conditions, these diodes exhibit both negative resistance and visible light emission characteristics.
RESONANCE BEHAVIOR OF THE DIELECTRIC CONSTANT OF GaAs AT MICROWAVE FREQUENCIES
Authors: Larrabee R. D. , Hicinbothem W. A.
Published: March 2005

It has been observed that the lattice dielectric constant of single-crystal gallium arsenide exhibits a broad resonance centered at about 9.5 GHz. The magnitude of the changes of dielectric constant associated with this resonance is comparatively large, but the magnitude of the losses associated with it is quite low. No satisfactory explanations for this resonance behavior has been suggested to date.
RUBY-LASER-PUMPED OPTICAL PARAMETRIC OSCILLATOR WITH ELECTRO-OPTIC EFFECT TUNING
Authors: Kreuzer L. B.
Published: March 2005

Optical parametric oscillation has been achieved in LiNbO3 in the range 1 to 1.08 μ with a peak parametric power of 38 × 103 W. The oscillator which was tuned both by rotation of the crystal in an external optical cavity and by the electro-optic effect was pumped at 6943 Å by a ruby laser of 3 × 106 W peak power. The observed electro-optic tuning agreed with that calculated from measured values of the electro-optic coefficients.
LUMINESCENCE FROM PLASTICALLY BENT CRYSTALS OF CADMIUM SULFIDE
Authors: Mitsuhashi Hiroji , Chikawa Jun-ichi , Nakayama Tadahisa
Published: March 2005

Plastically bent crystals of CdS exhibit different luminescent spectra at 77°K depending on the type of edge dislocations. The bending of the crystals around an axis in a [01̄10] direction permits selective introduction of either Cd or S dislocations after completion of polygonization in conformity to the sense of the bending. The crystals with S dislocations showed two emission bands at about 6350 Å and 7400 Å of much more brightness than those with Cd dislocations.
THE ANOMALOUS APPEARANCE OF LASER OSCILLATION AT 6401 Å
Authors: Tobias Irwin , Strouse William M.
Published: March 2005

The anomalous appearance of 6401 Å He-Ne laser oscillation in certain cavity configurations is attributed to the presence in the active medium of a radial variation in the density of neon atoms in the 1s5 metastable level. A number of experiments are described which test this hypothesis and the results of all are consistent with it.
CRITICAL CONDUCTION AND INDUCED CURRENTS IN THE SURFACE OF Nb (25%) Zr RIBBON AT LOW FIELDS
Authors: Chang C. T. M. , LeBlanc M. A. R.
Published: March 2005

The level of conduction and induced currents required for the onset of entry or exit of flux in an ``infinite'' slab of Nb (25%) Zr ribbon cooled through Tc in a static, parallel magnetic field depends on the sense of the currents. A small Meissner effect is observed in this material. We argue that a net paramagnetic current is induced in the surface layer during cooling through Tc in a static field H < Hc2.
A SEALED-OFF MICHELSON TYPE CO2 LASER FOR DIAGNOSTIC STUDIES OF GASEOUS PLASMAS
Authors: Witteman W. J.
Published: March 2005

An experimental arrangement of a Michelson type CO2 laser for plasma diagnostic studies of ac discharges is described. The principle of the apparatus is based on the phenomena of strong competition between the rotational transitions. If a phase shift is caused by the plasma to be studied, the intensity distribution of the lasing transitions is changed. The system has been used successfully for measuring (with a wavelength of 10.6 μ) changes in refractive index on the order of 10−9.
SPECTROSCOPIC DETERMINATION OF Cs (62P1/2) EXCITED STATE CONCENTRATIONS IN Cs-Ar LOW-PRESSURE GAS DISCHARGES
Authors: Bleekrode R. , Van Trigt C.
Published: March 2005

The results of a spectroscopic determination of the concentration of excited Cs atoms in the 62P1/2 state as present in a low-pressure Cs-Ar discharge are presented. The concentrations are calculated from the measured absorption from a continuum source using a numerically calculated curve of growth for which the effects of hyperfine splitting are properly taken into account. At low current densities the excited state concentration varies linearly with the free electron concentration and the Cs ground state concentration as well. This result is used to estimate the effect of the trapping of the 62P1/2−62S1/2 resonance radiation on the lifetime of the 62P1/2 state.
TEMPERATURE DEPENDENCE OF MICROWAVE EMISSION FROM INDIUM ANTIMONIDE
Authors: Poehler T. O.
Published: March 2005

The microwave emission characteristics of n-type indium antimonide have been studied as a function of temperature and magnetic field intensity. Microwave emission at 10 GHz has been detected at temperatures as high as 250°K in a magnetic field of 6.5 kOe.
COUPLING BETWEEN SLOW WAVES AND CONVECTIVE INSTABILITIES IN SOLIDS
Authors: Hammer J. M.
Published: March 2005

In an interaction between slow electromagnetic waves carried by metallic circuits and drifting carriers in solids it is shown that the presence of negative differential mobility inhibits the traveling-wave tube type of interaction at electron drift velocities greater than the phase velocity. At electron drift velocities below the wave phase velocity, however, the presence of negative differential mobility provides gain. The result agrees with the physical picture of an ``absorption'' by a negative resistance giving wave growth.
CONTRIBUTIONS OF SURFACE STATES TO MOS IMPEDANCE
Authors: Preier Horst
Published: March 2005

The broad time constant dispersion of states at the Si-SiO2 interface can be explained by the tunneling model introduced by F. P. Heiman and G. Warfield.1 The spectrum of time constants is caused by the exponential decay of the effective capture cross section for larger tunneling distances. A good agreement between theory and experiments was obtained for the oxide traps concentrated within about 10 Å from the interface.
A COMPARISON OF THE HOT IMPLANTATION BEHAVIOR OF SEVERAL GROUP-III AND -V ELEMENTS IN Si AND Ge
Authors: Mayer J. W. , Davies J. A. , Eriksson L.
Published: March 2005

The orientation dependence of the backscattered yield of 1.0-MeV helium ions has been used to determine the lattice location of several group-III and group-V elements implanted at elevated temperatures in Si and Ge. We find that for the slower diffusants, i.e. group-V elements in Si and group III in Ge, a considerably higher fraction is located on substitutional sites than for the faster diffusants. The concentration of Sb and Bi on substitutional lattice sites can exceed the equilibrium solubility by at least an order of magnitude. For In and Tl in Si, we find equal numbers of ions on the 〈111〉 interstitial lattice sites and on the substitutional lattice sites which suggest that some sort of pairing occurs between interstitial and substitutional impurities; again, the substitutional content can exceed the equilibrium solubility limit by large factors.
EFFECT OF COMPRESSIVE UNIAXIAL STRESS ON HIGH FIELD DOMAINS IN n-TYPE Ge
Authors: Smith John E. , McGroddy James C.
Published: March 2005

The effect of compressive uniaxial stress on the threshold field for nucleation of high field domains in n-type Ge at 27°K has been measured. The increase in threshold field is approximately quadratic in stress and is about 15% for a stress of 104 kg/cm2 applied along a 〈100〉 direction parallel to the current and about 37% for a stress of 104 kg/cm2 applied along a 〈100〉 perpendicular to the current. These results indicate that, while in a strong electric field the 〈110〉 valleys are occupied at high stresses, transfer of electrons to these valleys is not the cause of bulk negative differential conductivity in n-type Ge.
MICROWAVE EMISSION DURING PLASMA FORMATION IN InSb
Authors: Van Welzenis R. G. , Van Den Dries J. G. A. M.
Published: March 2005

X-band microwave emission from n-type InSb during avalanche plasma formation at 77°K is reported. A magnetic field is not required.
OBSERVATION OF THE SPECTRUM OF MICROWAVE RADIATION SCATTERED FROM A NONEQUILIBRIUM LIQUID
Authors: Iannuzzi M.
Published: March 2005

Measurements of the spectrum of microwave radiation scattered from a nonequilibrium liquid (CCl4 at 71°C) are presented. It is shown that the mean drift velocities of the refractive index inhomogeneities responsible for the scattering can be measured. The experimental results are consistent with the theory of wave propagation in a turbulent medium.
NONCOLLINEAR PARAMETRIC SCATTERING OF VISIBLE LIGHT
Authors: Magde Douglas , Scarlet Richard , Mahr Herbert
Published: March 2005

Experimental observations of noncollinear parametric interactions in ADP pumped by 3472-Å laser light are reported for a wide variety of signal and idler frequencies, crystal orientations, and observation directions. The results provide the first confirmation of the predictions of newly extended theory.
HOT ELECTRON RELAXATION TIMES IN TWO-VALLEY SEMICONDUCTORS AND THEIR EFFECT ON BULK-MICROWAVE OSCILLATORS
Authors: Das P. , Bharat R.
Published: March 2005

The momentum and energy relaxation times of a two-valley semiconductor are calculated as functions of the electron temperatures in different valleys. From the expression for the small signal microwave current under hot electron conditions, the upper frequency limit of the bulk-microwave devices is estimated.
CARRIER MOBILITY IN CdF2
Authors: Lebedev E. A. , Frukacz Z. , Niemyski T.
Published: March 2005

The carrier mobility in monocrystalline CdF2 was investigated. It was proven that only electron mobility was measured, and exponential rise of mobility with temperature was obtained.
INFRARED QUANTUM COUNTER ACTION IN Ho-DOPED CRYSTALS
Authors: Gualtieri J. G. , DeLhery G. P. , AuCoin T. R. , Pastore J. R.
Published: March 2005

Infrared quantum counter action of Ho3+ in CaWO4, SrWO4, NaLa(WO4)2, CaMoO4, CdF2, and YAG single crystals is reported for the first time. A new two-step excitation is also reported for Ho3+ in CaF2. Total quantum efficiencies were experimentally calculated for some of the stronger processes, and one of these is compared to a theoretical estimate for the internal quantum efficiency.
A COMPARISON BETWEEN NEUTRON DAMAGE IN ANNEALED GOLD AND IN QUENCHED GOLD
Authors: Cotterill R. M. J.
Published: March 2005

The defects that can be resolved as dislocation loops (with diameters in the range 100–500 Å) in neutron-irradiated gold are completely suppressed if the gold initially contains stacking-fault tetrahedra. It is inferred that these loops are of the interstital type.
INFRARED BIREFRINGENCE OBSERVATIONS ON ELECTRON-BOMBARDED SILICON
Authors: Carron Gene J.
Published: March 2005

Polarized infrared radiation was used to study the birefringence surrounding localized thermal strains in single-crystal silicon due to electron beam bombardment. These localized spots had previously exhibited four-lobed rosette stress patterns when examined by x-ray topography. The interest lies in the crystal optics effects relating these observed phenomena.
OPTIMUM HETERODYNE DETECTION AT 10.6 μm IN PHOTOCONDUCTIVE Ge:Cu
Authors: Teich M. C. , Keyes R. J. , Kingston R. H.
Published: March 2005

A measurement of the signal-to-noise ratio and minimum detectable power for heterodyne detection of scattered radiation at 10.6 μm has been made. Using photoconductive Ge:Cu as the detector, the observed minimum detectable power, at a frequency of 70 kHz and in a bandwidth of 270 kHz, was 3.5 × 10−14 W. This corresponds to a minimum detectable power of 1.3 × 10−19 W in a 1-Hz bandwidth, which is within a factor of 10 of the theoretically perfect photon counter.
SPATIALLY RESOLVED LASER HETERODYNE MEASUREMENTS OF PLASMA DENSITIES IN WEAKLY IONIZED GASES
Authors: Verdeyen J. T. , Cherrington B. E. , Fein M. E.
Published: March 2005

A two-wavelength He:Ne laser heterodyne system has been successfully used to measure electron number densities in the range from 4 × 1012 cm−3 to 1011 cm−3, over a path length of 24 cm. These experiments were performed on a single-shot basis in pulsed argon discharges. The spatially resolved laser measurements compared quite favorably with integrated electron density measurements made with a microwave cavity operating in the TM010 mode.
SURFACE EXCESS CONDUCTANCE IN GERMANIUM TUNNEL JUNCTIONS VIA SURFACE STATES
Authors: Alberghini J. E. , Broudy R. M.
Published: March 2005

Following cleavage through p-n junctions on degenerate n-type and p-type germanium in liquid nitrogen, a large additional exponential contribution to the excess current has been observed. It is established that this excess is associated with the clean surface at the junction. Inversion layer conduction is shown to be negligible. Experimental evidence supports the interpretation that the surface excess is due to tunneling via surface states.
THEORY OF THE OPTICAL FREQUENCY TRANSLATOR
Authors: Garrett C. G. B. , Duguay M. A.
Published: March 2005

The Duguay, Hargrove, Jefferts frequency translation experiment is analyzed in terms of superposition of side bands. It is shown that a Gaussian input pulse leads, in a good approximation, to a Gaussian output pulse translated in frequency, so long as the modulation index is not so large as to lead to a translation, in units of the inter-mode spacing, of the order of the cube of the number of modes of appreciable amplitude in the input pulse.
NOISE STUDIES IN UNIFORM AVALANCHE DIODES
Authors: Haitz Roland H. , Voltmer Fred W.
Published: March 2005

This Letter reports avalanche noise studies on microplasma-free guard-ring avalanche diodes. The low and high frequency approximations of Hines' theory are compared with experimental results at 1 kHz and 3 to 9 GHz, respectively. Good agreement is found between experiment and theory at both low and high frequencies. The open-circuit spectral voltage density is white up to the avalanche frequency ωa and decreases inversely with current. For ω ≫ ωa the spectral noise power density falls off with ω4.
ELECTRON-HOLE GENERATION IN GaAs
Authors: Conwell Esther M.
Published: March 2005

Experimental findings have been interpreted by Copeland as indicating that the multiplication rate α(E) of carriers in GaAs has a narrow peak between 3 and 10 kV/cm. It is argued here that theory can account for a sizeable α at these low fields, but that, rather than having a maximum and decreasing to zero again, α will continue to rise. The proposed variation of α appears to be more consistent with experimental results.
ELECTRIC-FIELD-INDUCED INFRARED ABSORPTION IN GaAs p-n JUNCTIONS
Authors: Burgiel J. C.
Published: March 2005

Experimental results are presented concerning a new form of electric-field-induced absorption of infrared light passing through the junction waveguide of a diffused GaAs diode. Changes in absorption constant of nearly 40 cm−1 have been observed at a wavelength of 0.94 μ upon the application of 20 V reverse bias. An explanation involving two physical mechanisms is proposed. The first is a Franz-Keldysh—like effect associated with shallow impurity levels. The second seems to be associated with a deeper impurity level.
HELICON—DRIFT CURRENT INTERACTION IN A LAYERED SEMICONDUCTOR STRUCTURE
Authors: Nanṅey C. A. , Libchaber A. , Garno J. P.
Published: March 2005

We have observed an interaction between helicon waves and drift currents in a layered lead telluride structure. In the low ωcτ regime of our experiments bulk wave effects are much greater than the surface wave interaction proposed by Baraff and Buchsbaum. Experiments performed on structures which have layers of equal dielectric constants and those with unequal dielectric constants both yield the same result; namely, the attenuation is reduced when the drift and wave propagate in the same direction and is increased when the two are in opposite directions. The observed interaction is strong and although spatial growth of the helicon waves has not yet been achieved with presently available drift velocities (Vdrift < Vphase), wave attenuation has been reduced by as much as 15 dB.
UNUSUAL CRYSTAL-FIELD ENERGY LEVELS AND EFFICIENT LASER PROPERTIES OF YVO4:Nd
Authors: O'Connor J. R.
Published: March 2005

The spectral properties of Nd-doped YVO4, grown from the melt, have been determined. In absorption the Stark split levels are reduced in comparison to other Nd-doped materials. The Nd ion appears to be in a cubic crystal field even though it substitutes for Y whose point symmetry is less than (42̄m). The reduced Stark splitting, caused by an admixture of 4f and 5d wave functions, leads to efficient, low-threshold laser action. Transfer of energy from the lattice to Nd ions is also observed.
RELATIVE INTENSITIES OF THE 5s2P3/2 → 4p2D5/2 AND THE 5s4P5/2 → 4p4D7/2 TRANSITIONS IN THE Ar II LASER
Authors: Marantz H. , Rudko R. I. , Tang C. L.
Published: March 2005

It has been found that the ratio of the spontaneous intensities of the 5s2P3/2 → 4p2D5/2 and the 5s4P5/2 → 4p4D7/2 cascade transitions in the CW Ar II laser is typically 1:11.
VARIATION OF DRIFT VELOCITY WITH FIELD IN GaAs
Authors: Conwell E. M. , Vassell M. O.
Published: March 2005

Solutions of the Boltzmann equation for GaAs have been used to calculate the variation of drift velocity, vd, with field, E. To represent the situation in moderately doped samples with low mobility an additional scattering process has been incorporated into the calculations. The results are in reasonable agreement with deductions about the vd vs E characteristic made from many types of experiments, but in disagreement with the measured vd vs E of Gunn and Elliott.
WHITE-LIGHT VIEWING OF SURFACE HOLOGRAMS BY SIMPLE DISPERSION COMPENSATION
Authors: De Bitetto D. J.
Published: March 2005

Two successful methods are reported for achromatizing the white-light reconstruction of a 2-beam surface hologram. One method uses prisms for dispersion compensation. The other uses a single-plane diffraction grating as the correcting element.
TRANSITION FROM A MOVING STRIATION TO A HELICAL OSCILLATION IN A POSITIVE COLUMN
Authors: Sato Masumi , Hatta Yoshisuke
Published: March 2005

A transition from a moving striation to a helical oscillation was observed in the positive column of a helium discharge at a pressure of 0.4 mm Hg as an applied longitudinal magnetic field was increased. The frequency and amplitude of the moving striation decreased with increasing magnetic field. When the magnetic field reached a critical value of about 1650 G, a helical oscillation appeared and the two waves were observed to coexist. The striation disappeared with a further increase of the field, but the helical oscillation continued to exist.
DIODE LASERS OF Pb1−ySnySe AND Pb1−xSnxTe
Authors: Butler J. F. , Calawa A. R. , Harman T. C.
Published: March 2005

Infrared laser emission at a number of wavelengths between 9.4 μ and 13.7 μ has been obtained from diodes of Pb1−ySnySe and Pb1−xSnxTe at 12°K and 77°K. Diodes were fabricated from vapor-grown Pb1−ySnySe and both vapor-grown and Bridgman-grown Pb1−xSnxTe. Emission data indicate that, as in Pb1−xSnxTe, the energy gap in Pb1−ySnySe decreases with increasing Sn concentration, becoming zero at 12°K for some value of y within the range 0.11 ≤ y ≤ 0.14.
INTERACTION OF FERROMAGNETIC AND SUPERCONDUCTING THIN FILMS
Authors: Artley J. L. , Buckley G. , Willis C. A. , Chambers W. F.
Published: March 2005

Experimental evidence is presented to show that the domain walls in a thin film of permalloy may be used to influence the transition of a thin indium film as it goes from the superconducting to normal state. The magnetic field of the domain walls in the permalloy film drives the superconducting indium toward a normal state and the superconducting indium film tends to lock the domain walls of the permalloy into a permanent position.
MEASUREMENT OF DIFFUSED SEMICONDUCTOR SURFACE CONCENTRATIONS BY INFRARED PLASMA REFLECTION
Authors: Gardner E. E. , Kappallo W. , Gordon C. R.
Published: March 2005

When infrared radiation is reflected from the surface of a degenerate semiconductor, a minimum is obtained in the reflection spectrum. This plasma minimum is related to the free carrier concentration, effective mass, and dielectric constant of the semiconductor. In a diffused semiconductor with high surface concentration, the absorption constant is high and consequently the reflected plasma minimum is directly related to the surface concentration of free carriers. By calibrating the plasma minima vs known impurity concentrations, it is possible to determine surface concentration in n- and p-type silicon ranging from 5 × 1018 to 5 × 1020 cm−3 using an infrared spectrometer with a wavelength span of 2.5 to 25 μ.
ACOUSTIC QUARTER-WAVE PLATES AT MICROWAVE FREQUENCIES
Authors: Auld B. A. , Quate C. F. , Shaw H. J. , Winslow D. K.
Published: March 2005

The use of birefringent acoustic media in microwave—shear-wave polarization transformers is described. Restrictions on the properties of the acoustic medium are discussed as well as the limitations imposed by the use of imperfect bonds between the transformer section and a delay medium. The principles are illustrated by application to a double-ended variable delay line.
TRANSIENT VOLTAGE BREAKDOWN DUE TO AVALANCHE IN MIS CAPACITORS
Authors: Goetzberger A. , Nicollian E. H.
Published: March 2005

Rapid generation of minority carriers under transient bias conditions is shown to occur by means of avalanche breakdown in an MIS capacitor. Capacitance vs pulse bias follows a 1/C2 law and saturates at a low value at the avalanche voltage. Breakdown fields and voltages in general agreement with those found in step p-n junctions for Si and GaAs are measured.
INFRARED AND MICROWAVE RADIATIONS ASSOCIATED WITH A CURRENT-CONTROLLED INSTABILITY IN GaAs
Authors: Liu S. G.
Published: March 2005

A current-controlled type negative resistance has been observed in low-resistivity GaAs samples. The onset of this current-controlled negative resistance is found following immediately a Gunn-type instability at its threshold field. Associated with the current-controlled negative resistance is observed radiation of infrared frequencies corresponding to the energy gap of the sample and broad-band microwave frequencies. Similar results have been observed in GaAs1-xPx samples.
OBSERVATION OF INTERFACIAL DISLOCATIONS IN THIN (100) AND (111) ELECTRODEPOSITS OF NICKEL ON COPPER
Authors: Thompson Earl R. , Lawless Kenneth R.
Published: March 2005

Bicrystal metal films were prepared by electrodeposition of nickel on evaporated, single-crystal copper films. Electron microscopic examination of the bicrystal films revealed interfacial dislocations which aid in reducing the misfit strain between the crystals. In both (100) and (111) bicrystals, misfit dislocations, aligned in <110> directions, were observed with Burgers vectors not contained in the interfacial plane. Glide of pre-existing or surface nucleated dislocations is suggested as the method by which this type of misfit dislocation is produced.
SWITCHING AND LOW-FIELD BREAKDOWN IN n-GaAs BULK DIODES
Authors: Copeland John A.
Published: March 2005

Switching effects have been observed in the current vs voltage curves of n-type GaAs diodes with resistivities between 0.3 and 5 Ω-cm. After switching, the diodes go into a constant-voltage avalanche breakdown state with a sustaining field of 4500 V/cm. These effects are attributed to a peak in the hole generation rate α between 3,000 and 10,000 V/cm caused by high energy electrons in the (000) valley of the conduction band.
DEMONSTRATION OF X-RAY DIFFRACTION BY LiF USING THE Mn Kα X RAYS RESULTING FROM 55Fe DECAY
Authors: Preuss Luther E. , Toothacker William S. , Bugenis Claudius K.
Published: March 2005

Mn K x rays from 55Fe were diffracted with detectable intensity by NaCl and LiF powder. A special diffractometer incorporating a 100-mc 55Fe linear source (1.5 mm × 10 mm) was used. Theoretical diffraction efficiency is about 10−5 (on the NaCl 200 plane). Diffractometer geometry provided 10−1 to 101 photons per min at the detector. This order of intensity was observed with a proportional counter, linear pulse amplifiers, and a multichannel analyzer. The three most intense beams of LiF (θ = 20° to 55°) were clearly demonstrated.
TIME AND SPATIALLY RESOLVED INTERFEROMETRY ON PULSED-LASER-INDUCED PLASMAS
Authors: Bruce C. W. , Deacon J. , Vonderhaar D. F.
Published: March 2005

A technique is described for the measurement of plasma density. Multiple beam interferometry gives simultaneous time and position information on the state of the laser-induced plasma. Experiments using a single interferometric probe at various distances from the target surface along the incident laser axis indicates that the leading edge of the blowoff absorbs a portion of the incident energy and hence additional fringe shifts are observed.
TEMPERATURE DEPENDENCE OF THE OPTICAL PROPERTIES OF FERROELECTRIC LiNbO3 AND LiTaO3
Authors: Miller R. C. , Savage A.
Published: March 2005

Linear and nonlinear optical investigations of LiNbO3 and LiTaO3 from room temperature to temperatures above their ferroelectric phase transitions are described. The measurements include studies of second harmonic generation with an Nd laser (1.06 μ) and determinations of the refractive indices as well as the birefringence at 0.6328 μ. All the optical data exhibit distinct changes at the Curie temperatures, Tc = 1195°C ± 15°C for LiNbO3, and Tc = 610°C ± 10°C for LiTaO3. In each case the phase change has the characteristics of a second-order ferroelectric transition. The uniaxial paraelectric phases are concluded to be centrosymmetric — probably space group R3̄c.
ZEEMAN LASER INTERFEROMETER
Authors: Dahlquist J. A. , Peterson D. G. , Culshaw W.
Published: March 2005

A laser interferometer which utilizes some Zeeman laser properties has been built and operated. The application of an axial magnetic field constrains a two-mode 633-nm He–Ne laser to oscillate simultaneously as left- and right-hand circularly polarized modes at the upper and lower cavity resonances, respectively. The two modes, separated by a quarter-wave plate and polarizers, are sent through different arms of an interferometer, and are recombined and detected with a photomultiplier. Target motions in one arm, ranging from displacements of 10−6 cm at 12 kHz to 10 cm at 0.5 Hz, produced easily resolvable signals in this heterodyne device.
EVIDENCE OF DISTANT-PAIR RECOMBINATION PROCESSES IN THE GREEN-EDGE EMISSION OF CdS AT 4.2° AND 77°K
Authors: Condas George A. , Yee Jick H.
Published: March 2005

The luminescence of single crystals of wurtizite CdS having a strong green-edge emission was studied at 4.2° and 77°K as a function of exciting intensity of steady 3650-Å light. The typical overlapping band structure of the green-edge emission, a zero phonon band with ∼300 cm−1 phonon replica bands, was seen to shift to longer wavelengths with decreasing intensity of the exciting light. This behavior, seen in the green edge of GaP, suggests that the green edge arises from the recombination of electrons and holes trapped on distant donor and acceptor pairs.
AN ACOUSTIC LIGHT MODULATOR FOR 10.6 μ
Authors: Dixon R. W. , Chester A. N.
Published: March 2005

Bragg diffraction from longitudinal acoustic waves in tellurium is employed to modulate the 10.6-μ output of a CO2–He laser. Two of the photoelastic tensor components are obtained and it is shown that the efficiency with which an acoustic wave in tellurium diffracts light greatly exceeds that of any other known material.
AVALANCHE RADIATION FROM THE BULK OF LONG, THIN, FORWARD-BIASED p+-p-n+ SILICON DIODES
Authors: Harman G. G.
Published: March 2005

Avalanche radiation has been observed from the bulk of long, thin, forward-biased p+-p-n+ silicon diodes with applied field strengths as low as 1000 V/cm. At higher fields, surface arc erosion streaks occurred and these followed crystallographic plane directions rather than the applied field orientation. Possible explanations are given for the several effects that contribute to the observed phenomena.
HOLOGRAPHIC DIFFRACTION GRATINGS
Authors: George Nicholas , Matthews J. W.
Published: March 2005

From a careful evaluation of a very simple hologram, the photographically produced grating, we have been able to obtain quantitative data on image reconstruction efficiency as a function of processing procedures and illumination parameters such as orientation angle and wavelength. Experimental results are presented which show the dependence of efficiency on exposure, both before and after bleaching of the emulsion layer. In addition, the orientation sensitivity of thick-emulsion holograms is studied, and it is shown that maximum diffracted power occurs when the Bragg reflection condition is satisfied.
PHOTON-MODULATED TUNNELING
Authors: Cohen Julius
Published: March 2005

Infrared photoconductivity is obtained in a thin-film structure, Al–Al2O3–Te–Au, and the evidence suggests that it is due to photon-modulated tunneling.
ENERGY OF THE PERIODIC BLOCH WALL
Authors: Janak James F.
Published: March 2005

A crude calculation of the energy of a Bloch wall subdivided into two segments of opposite polarity is given. It is shown that the energy of this structure is lower than that of the ordinary Bloch wall only if the anisotropy constant K is sufficiently small. Thus one expects to observe subdivided Bloch walls only in low-anisotropy ferromagnetic materials.
A NEW IONIZING RADIATION DETECTION CONCEPT WHICH EMPLOYS SEMICONDUCTOR AVALANCHE AMPLIFICATION AND THE TUNNEL DIODE ELEMENT
Authors: Locker Robert J. , Huth Gerald C.
Published: March 2005

A concept for the detection of ionizing radiation which utilizes the inherent high speed and large amplitude of the induced charge pulse in a semiconductor avalanche detector coupled with the tunnel diode element is described. It has been shown possible to digitally detect extremely low energy events even in high-current-induced noise backgrounds in the avalanche detector. Cryogenic cooling is not required. Detection is accomplished by use of the rate of rise and magnitude of the nuclear pulse (or alternatively a pulse of suitable amplitude and rate of rise generated by optical photons). The high-speed time domain allows discrimination against all noise-generated events because charge is not integrated in this scheme.
LASER ACTION IN OPTICALLY-PUMPED CN
Authors: Pollack M. A.
Published: March 2005

Laser oscillation near 5.2 μ has been observed during the flash photolysis of cyanogen (C2N2). A total peak power of more than 10 mW was obtained on three lines, identified as vibrational-rotational transitions in the ground electronic state of CN. The optimum pressure was found to be about 20 torr of cyanogen. Optical pumping is the only mechanism now known to produce laser action on these transitions.
COHERENT MICROWAVE EMISSION FROM INDIUM-ANTIMONIDE STRUCTURES
Authors: Swartz G. A. , Robinson B. B.
Published: March 2005

Coherent microwave power at K-band frequencies has been generated by bars of p-type indium antimonide with recrystallized surfaces and bars of indium antimonide with layered p and n regions. At an ambient temperature of 77°K, electric and magnetic fields are applied to the rod at an angle θ, to each other. A theory which considers the two-stream interaction in a transverse magnetic field is presented. The output frequency predicted by the theory is in the range of experimental observation.
STUDY OF THE EARLY STAGES OF THE EPITAXY OF SILICON ON SILICON
Authors: Jona F.
Published: March 2005

Observations of low-energy electron diffraction patterns reveal that the epitaxial temperature for Si films is approximately 400°C on clean Si {111} surfaces and tends to be lower, although less well defined, on clean Si{100} surfaces. A few monolayers deposited at room temperature on{111} are amorphous, on{100} they exhibit the bulk structure. The recrystallization process of an amorphous surface layer occurs by way of an ``intermediate'' phase, characterized by periodic modulations of lattice spacing and scattering factor, and an ``ideal'' phase that corresponds to simple termination of the bulk lattice. The transition from the latter to the reconstructed surface structure occurs by way of antiphase domains.
ELECTRIC BREAKDOWN MECHANISM IN CUPROUS CHLORIDE SINGLE CRYSTALS
Authors: Gentile A. L.
Published: March 2005

Electrical breakdown in cuprous chloride single crystals was observed to be caused by copper precipitated as either filaments with dendritic branches or as networks. A method was found to out-diffuse the copper and thereby increase the resistivity of the material.
NEW VISIBLE CW LASER LINES IN SINGLY-IONIZED CHLORINE
Authors: Zarowin C. B.
Published: March 2005

Three new visible CW laser lines are reported and identified in Cl II. These lines are at the following wavelengths: 4132.5 Å, 4740.4 Å, 5103.1 Å.
A HIGH-GAIN InAs THIN-FILM TRANSISTOR
Authors: Brody T. P. , Kunig H. E.
Published: March 2005

InAs thin films have been prepared by coevaporation. Hall mobilities up to 8000 cm2/V-sec have been obtained in films 3000-Å thick, and 3000 cm2/V-sec in 1000-Å films. Field-effect transistors have been fabriacted of such films, exhibiting good saturation in both enhancement and depletion modes of operation. Field-effect mobilities of 1800 cm2/V-sec, transconductances of 10,000 μ-mhos and gain-bandwidth products of 8 MHz were obtained in devices with a 100-μ source-drain spacing. Performance in the GHz region is predicted for devices of suitable geometry.
NEAREST-NEIGHBOR ELECTRON SCATTERING IN SILICON
Authors: Taub H. , Stern R. M.
Published: March 2005

LEED observations between 200–1000 V on the clean (111) face of silicon indicate a set of diffuse rings which, contrary to normal behavior of diffraction features, move outward from the normal with decreasing electron wave-length. The origin of these rings is determined to be multiple scattering from nearest-neighbor pairs. Estimates of the electron mean free path average about a value larger than the nearest-neighbor distance but smaller than the separation of nearest-neighbor pairs in the (111) direction. The rings appear to be associated with Kikuchi patterns which are observed down to 400 V.