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Introduction Elevated interleukin (IL)-6 occurs in patients with active rheumatoid arthritis (RA), which has been shown to lead to a decrease in cytochrome P450 (CYP) enzyme activity and alterations in drug concentrations metabolized by CYP. IL-6 signaling blockade by IL-6 receptor (IL-6R) antagonists may reverse this effect of IL-6 and restore CYP activity. This study evaluated the pharmacokinetic profile of simvastatin (a CYP3A4 substrate) before and 1 week after a single dose of sarilumab (a human monoclonal antibody [mAb] blocking the IL-6Rα) in patients with RA, to assess potential interaction. Methods Nineteen patients with active RA received oral simvastatin 40 mg 1 day before and 7 days after subcutaneous injection of sarilumab 200 mg. The pharmacokinetic parameters of simvastatin and its primary metabolite, β-hydroxy-simvastatin acid, were calculated using noncompartmental analysis. Results Compared with simvastatin alone, single-dose simvastatin administration 7 days after single-dose sarilumab administration in patients with RA resulted in reduced simvastatin and β-hydroxy-simvastatin acid exposure in plasma. Mean effect ratios (90 % confidence interval) for simvastatin peak plasma concentration (C max) and area under the concentration–time curve extrapolated to infinity (AUC∞) were 54.1 % (42.2–69.4 %) and 54.7 % (47.2–63.3 %), respectively. No changes occurred in time to C max or half-life for either simvastatin or β-hydroxy-simvastatin acid after sarilumab administration. Conclusions Sarilumab treatment resulted in a reduction in exposure of simvastatin, consistent with reversal of IL-6-mediated CYP3A4 suppression in patients with active RA, as was reported for tocilizumab with simvastatin and for sirukumab with midazolam. Clinical trial registration number NCT02017639. Electronic supplementary material The online version of this article (doi:10.1007/s40262-016-0462-8) contains supplementary material, which is available to authorized users.

The stepwise electrochemical oxidation of p-methoxyphenol and hydroquinone at boron-doped diamond (BDD) electrodes was investigated in perchloric acid media using rotating ring–disk electrode (RRDE) and hydrodynamic modulation techniques. Initial oxidation of these compounds to p-benzoquinone at the disk may be confirmed by reduction of the quinone at the ring electrode. Further oxidation, ultimately to CO2, can be followed by the loss of redox active products at the ring. Comparison of BDD anodic activity to those of graphite, gold, and platinum electrodes, utilizing RRDE configurations, shows that the high oxygen evolution overpotential exhibited by BDD allows for more efficient anodic conversion of p-methoxyphenol and hydroquinone to products beyond the quinone stage. BDD, unlike the other electrode materials, showed no corrosion or fouling when used under these conditions. These results complement product analysis studies by other groups on BDD for organic contaminant remediation by exhaustive electrolysis.

Rotating and hydrodynamically modulated rotating disk electrodes of boron-doped diamond (BDD) and tetrahedral amorphous nitrogen incorporated carbon (taC : N) were employed to extend analytical sensitivity and linear current response of these materials for dopamine analysis at physiological pH to 200 nM. Hydrodynamically modulated rotating disk electrode (HMRDE) techniques discriminate against nonmass transfer limited components, allowing more complete implementation of the wider electrochemical window of these materials. Experiments performed in the presence of ascorbate showed typical catalytic enhancement of the dopamine oxidation current and a corresponding loss of response to dopamine quinone at the ring in a rotating ring-disk electrode (RRDE) configuration. Utilizing these phenomena, a RRDE method for simultaneous determination of both dopamine and ascorbate concentrations in solutions containing comparable levels of both species is presented.

The voltammetric determination of dopamine in the presence of ascorbic acid is strongly dependent on the local transport conditions because of the reduction of the product quinone with the ascorbate. Rotating ring-disk electrodes (RRDE) may be applied both to the kinetics of this system and to analytical advantage in detecting trace amounts of ascorbate. In the present work, RRDE techniques were used to determine the rate constant by which oxidized dopamine, generated at the disk, was reduced by ascorbate present in solution. This was accomplished by comparing the current generated at the ring by reduction of unreacted dopamine quinone to the amount predicted by theory for an infinitely fast reaction rate. Rate constants were obtained for ascorbate concentrations from 100 to 400 μM and dopamine concentrations from 2 to 10 mM using three different electrodes. A second-order rate constant of 1.5 × 106 M-1 s-1 was found.

Self-assembly of C60 molecules on planar n- or p-type Si(100) has been accomplished by direct tethering onto the Si surface without using any intermediate functional hydrocarbon chain. Photoresponse has been observed on these monolayer modified electrodes in both aqueous and nonaqueous media. The p-type Si(100) surface with a bound C60 monolayer is also capable of mediating redox reactions. These C60 monolayer modified Si electrodes are very stable in both acidic aqueous and polar nonaqueous solvents. Characterization by fast atom bombardment mass spectroscopy (FAB−MS) suggests that simultaneous hydrosilylation and hydrogenation reactions account for the nature of the monolayer formation.

Electrochemical studies of the products of C{sub 60} {gamma}-irradiated in cyclohexane were conducted using the frequency response of hydrodynamic modulation at rotating disk electrodes (HMRDE) to determine transport properties by a methodology independent of the concentration of the electroactive species. The diffusion coefficients of C{sub 60} and its {gamma}-irradiated product were separately determined to be 1.9 {times} 10{sup {minus}6} and 0.96 {times} 10{sup {minus}6} cm{sup 2}/s, respectively, at 50 C. The estimated Stokes radius of the radiolytic product of C{sub 60} approaches twice that of the fullerene itself. Such a result for {gamma}-radiolysis in cyclohexane solution is consistent with the formation of cyclohexane adducts and likely some C{sub 60} dimer.

The mechanisms of silver and mercury metal deposition on boron-doped diamond electrodes were investigated using a prior model of three-dimensional diffusion controlled nucleation/growth to interpret the data. The mechanism of nucleation depends upon the nucleation overpotential and metal ion concentration. At low overpotentials, instantaneous nucleation can be observed and, at high overpotentials or concentrations, the process becomes progressive. No underpotential phenomena are observed, consistent with exceptionally weak interaction between the deposited metal and the diamond surface. Active sites corresponding to a low density of surface sites on the electrode which act as critical nuclei during the electrodeposition. Anodic reactions of silver were also investigated. It was found that the resulting product depends on the silver concentration in the solution. Soluble Ag(II) forms only at low concentration (

Morphological, spectroscopic, and electrochemical aspects of boron-doped diamond (BDD) films grown on silicon surfaces originating from three different laboratories have been examined by atomic force microscopy (AF), Raman scattering, Auger electron spectroscopy, and cyclic voltammetry in polyethylene oxide LiClO{sub 4} electrolytes in ultrahigh vacuum. All specimens displayed AFM images characteristic of diamond and Raman spectra consistent with a wide range of boron concentrations (10{sup 19} to 10{sup 21} B atom/cm{sup 3}), with no evidence for the presence of gross graphitic impurities. The cyclic voltammetry of two of the specimens (denoted as GV2 and CWRU), however, showed features at potentials positive to lithium bulk deposition attributed to lithium-ion intercalation/deintercalation phenomena in non-diamond carbon present as a surface impurity, perhaps at the grain boundaries. This finding is consistent with earlier results for a specimen of type GV2 in aqueous electrolytes for which rates of heterogeneous electron transfer for certain redox couples were found higher than those for nominally clean BDD surfaces.

Electronic and structural aspects of a MnO{sub 2} electrode in a rechargeable MnO{sub 2}/Zn battery environment have been investigated by in situ Mn K-edge x-ray absorption fine structure (XAFS). The relative amplitudes of the three major Fourier transform shells of the extended XAFS function of the rechargeable MnO{sub 2} electrode in the undischarged state were similar to those found for ramsdellite, a MnO{sub 2} polymorph with substantial corner-sharing linkages among the basic MnO{sub 6} octahedral units. The analyses of the background-subtracted pre-edge peaks and absorption edge regions for the nominally 1-e{sup {minus}} discharged electrode were consistent with Mn{sup 3+} as being the predominant constituent species, rather than a mixture of Mn{sup 4+} and Mn{sup 2+} sites. Furthermore, careful inspection of both the x-ray absorption near edge structure and EXAFS indicated that the full recharge of MnO{sub 2}, which had been previously discharged either by one or two equivalent electrons, generates a material with decreased corner-sharing linkages compared to the original undischarged MnO{sub 2}.

Since the introduction of practical work in DNA technology to school science courses, there has been a need to expand on the limited set of available protocols to demonstrate further biological principles. The current paper sets out two additional practical exercises which can be used in schools. The first experiment involves restriction analysis of bacteriophage lambda DNA to map its cos sites, and in the second experiment the effect of methylation of lambda DNA on restriction enzyme digestion is examined. Based on practical exercises already widely available, these protocols extend analysis of actual molecular events and aid in their interpretation (Miller, 1993, 1994; Madden, 1993; Harrison, Sampson, and Harrison, 1992).

Following the introduction of practical work in DNA technology to school science courses using the inexpensive DNA kits produced by Science and Plants for Schools (SAPS) and the National Centre for Biotechnology Education (NCBE), there is a need to expand the limited set of available protocols. This paper describes a computer simulation for schools and colleges which complements the laboratory work with DNA kits. This enables a pupil to predict initial restriction maps which may later be checked by electrophoresis. It outlines the principles of construction of restriction maps from base (or nucleotide) sequence and gel electrophoresis data. Keywords: DNA, Restriction analysis, Mapping

Physical, spectral and chromatographic data for all 209 individual PCB congeners is presented. The individual congeners were synthesized and then isolated and purified.Recent emphasis on the source of the toxicity of commercial PCB formulations has increased the need for a complete set of the PCB congeners. Through the use of two capillary GC columns: 40% octadecyl/ 15% phenyl methyl siloxane and 50% phenyl methyl siloxane, it was possible to separate 201 PCB congeners with only four unresolved pairs. The data compiled in this study for all 209 congeners will aid in the identification of selected individual components of these environmental pollutants. The use of this data also presents the opportunity for the improved quantification of the commercial PCB formulations.

We discuss wavelength tuning and its corresponding quantum efficiency modulated by the standing wave effects in a resonant-cavity enhanced (RCE) photodetector. Specific design conditions are made for a thin In/sub 0.53/Ga/sub 0.47/As (900 /spl Aring/) photodetector wafer-fused to a GaAs-AlAs quarter wavelength stacks (QWS). Analytic expressions for the calculation of resonant wavelength and standing wave effects are derived, using a hard mirror concept of fixed phase upon reflection, and are found to agree reasonably well with the exact numerical approach, using a transmission matrix method. We then experimentally demonstrate that wavelength tuning as large as 140 nm and its corresponding quantum efficiency modulated by the standing wave effects are clearly observed in our wafer-fused photodetectors, consistent with the predictions. The external quantum efficiency at 1.3 /spl mu/m wavelength and absorption bandwidth for the wafer-fused RCE photodiodes integrated with an amorphous Si-SiO/sub 2/ dielectric mirror are measured to be 94% and 14 nm, respectively. This technique allows the formation of multichannel photodetectors with high quantum efficiency and small crosstalk, suitable for application to wavelength demultiplexing and high-speed, high-sensitivity optical communication systems. >

Electrodes of conductive nitrogen‐incorporated tetrahedral amorphous carbon films deposited at ambient temperatures are shown to possess an extraordinary combination of the stability associated with boron‐doped diamonds and greatly enhanced electrocatalytic properties. In this first communication on the electrochemistry of deposited thin films of , we show that this material demonstrates more active charge transfer properties on a variety of systems relative to the , highly boron‐doped diamond . Stability is shown by chlorine evolution from solution for times the coulombs necessary for oxidation to of a thick film without noticeable change of the voltammetry. Propitious attributes result from the high nitrogen content coupled with the mixed character of the amorphous semiconductor, which can be deposited at room temperature on practically any substrate. ©1999 The Electrochemical Society

The reductions of and fullerenes in o‐dichlorobenzene (ODCB) electrolytes under controlled potential and convection at rotating disk and ring‐disk electrodes (RDE and RRDE) illuminate several aspects of the electron transfer processes. The stability of the successive one‐electron transfer products (up to and ions) is demonstrated through the RRDE. The diffusion coefficients of both fullerenes in ODCB/0.5M tetra n‐butyl ammonium bromide were measured by two RDE techniques, Levich limiting current behavior and the frequency response of sinusoidal hydrodynamic modulation (SHM). The former gave values of at 25°C for and , respectively, and the latter results were theoretically consistent with the Schmidt number of 17,400 so calculated, confirming the number of electrons transferred without the aid of Faraday's law. Voltammograms of the SHM current at the RDE show kinetic effects at the foot of each successive wave.

Ba1−xKxBiO3 is to date the highest Tc member of a class of superconductors which, it could be argued, belong in the same class of materials as the copper oxides. While there are striking differences between the bismuthates and the cuprates, there are some similarities. In this paper, we will report the results of our tunneling measurements on BKBO. The determination f the energy gap in this material suggests that it is a relativity weakly coupled BCS superconductor - a similar conclusion is reached in the sister compound BaPb1−xBixO3. These results are substantailly different from similar measurements in the cuprates. In addition, we have studied the background tunneling conductance in four of the compounds in this class (BaPbO3, BaPb1−xSbxO3, BaPb1−xBixO3 and Ba1−xKxBiO3) and find a remarkable correlation between the strength of the linear conductance and the superconducting transition temperature. Finally, the Josephson tunneling in these compounds will be discussed.

Anodic electrosynthesis of Ba 0.6 K 0.4 BiO 3 leads to millimeter-sized crystals of this cubic superconductor with transition temperatures of 30.5 K. Clusters of these lustrous blue-black crystals are grown on gold anodes in graphite crucibles which conveniently serve as the cathode. Details of the electrochemical procedure utilizing a hydroxide melt are given, along with the characterization of the superconductive transition by microwave absorption and magnetic measurements, and confirmation of the composition and structure with X-ray diffraction. The availability of crystals with cubic facets of up to 10 mm 2 has facilitated characterization and application of this material.

A generator—detector mode with the rotating ring—disk electrode has been used to determine the difference between Pd and Pt electrode behaviour and the origin of the larger overpotentials at Pd-hydrogen evolving cathodes. The use of thin film Pd disk electrodes has allowed full hydrogen or deuterium charging of the metal phase in short times. The electrode system has made feasible simultaneous measurements of the hydrogen uptake in PdH x films where the maximum composition reached was PdH 0.81 . Alloying Ni into Pd decreases the maximum hydrogen absorption by solid solution PdNi films to near zero at 17% Ni. The outgassing of hydrogen on open circuit from variously charge electrodes can be followed in real time and shows the losses associated with transfer of specimens to post-analysis (∼6% in 5 min).

We propose and demonstrate a novel high-speed and wavelength insensitive Y-branch modulator in InGaAsP multiple-quantum-wells that exhibits negligible chirp and is also suitable for achieving controllable chirp. We raise the refractive index on one arm via applied bias and use the unbiased arm as a modulator. As the light switches to the biased arm, the modulated light in the unbiased arm experiences little phase change and therefore exhibits negligible chirp. Tunable chirp may be achieved using a push-pull bias configuration. We demonstrate that our modulator chirp is /spl sim/10 times lower than that of typical electroabsorption modulators.

We demonstrate a novel Y-branch digital switch with a double-etch waveguide structure to greatly enhance the loss and crosstalk performance. The double-etch design increases the coupling between the two tapered Y-branch waveguides, which allows for efficient switching while decreasing the radiation loss that arises from the branching angle. This combined advantage also allows us to reduce the switch length, which in turn results in an efficient high-speed design. The measured crosstalk and loss are -19 and 3 dB, respectively, for a 3-mm-long switch. Further crosstalk reduction is expected from the simulation of a more optimized design.

Measurements of the flux of copper species reaching the ring electrode of a rotating Nd2CuO4−xFx disk-gold ring electrode configuration in acidified chloride solutions allow for the real-time analysis of x as the superconductor is etched. The method is based on analyzing the ratio of copper oxidation states arising from the open circuit dissolution reaction of the Nd2CuO4−xFx disk into chloride solutions. Through voltammetry at the gold ring electrode, the Cu2+ and Cu1+ products are measured quantitatively and x determined. For specimens showing a 27 K onset of Tc, the average copper oxidation state is 1.74, corresponding to the stoichiometry Nd2CuO3.74F0.26. Superconductor electrode potentials are determined directly by the Cu2+/Cu1+ ratios.

RATIONALE: The tachykinins substance P and neurokinin A (NKA) are implicated in the pathophysiology of asthma. Objective: We tested the safety, tolerability, and pharmacologic and biological efficacy of a tachykinin NK(1)/NK(2) receptor antagonist, AVE5883, in patients with asthma in two double-blind, placebo-controlled crossover studies. METHODS: The pharmacologic efficacy of a single inhaled dose (4.8 mg) of AVE5883 was tested against inhaled NKA in 20 patients with asthma. Subsequently, we studied the biological efficacy of the pharmacologically effective dose on inhaled allergen in a multiple-dose trial (4.8 mg three times per day, 9 d) in 12 patients with asthma with dual responses to inhaled house dust mite. On Day 8, an allergen challenge was conducted, and airway response was measured by FEV(1) until 9 hours postallergen. Exhaled NO, provocative concentration of methacholine bromide causing a 20% fall in FEV(1), and induced sputum were performed on Days 1, 7, and 9. RESULTS: AVE5883 had a bad taste, and transient bronchospasm occurred in some subjects. A single inhaled dose shifted the dose response to NKA by 1.2 doubling doses. Pretreatment with multiple doses of AVE5883 enhanced the allergen-induced early and late airway responses. There were no significant differences in the allergen-induced changes in exhaled NO, provocative concentration of methacholine bromide causing a 20% fall in FEV(1), and sputum cell differentials between placebo and AVE5883. CONCLUSIONS: Despite its demonstrated pharmacologic activity against inhaled NKA, multiple doses of AVE5883 increased the allergen-induced airway responses without affecting markers of airway hyperresponsiveness and airway inflammation. Our data question the prominent role of neurogenic inflammation in asthma and, consequently, the therapeutic potential of dual tachykinin antagonists

Objective: To evaluate immune responses to neoantigen and recall antigens in healthy subjects treated with teriflunomide. Methods: This was a randomized, double-blind, placebo-controlled study. Subjects received oral teriflunomide (70 mg once daily for 5 days followed by 14 mg once daily for 25 days) or placebo for 30 days. Antibody responses were evaluated following rabies vaccination (neoantigen) applied at days 5, 12, and 31 of the treatment period. Occurrence of delayed-type hypersensitivity (DTH) to Candida albicans, Trichophyton, and tuberculin (recall antigens) was assessed before and at the end of treatment to investigate cellular memory response. Safety and pharmacokinetics were evaluated. Results: Forty-six randomized subjects were treated (teriflunomide, n = 23; placebo, n = 23) and completed the rabies vaccination. Geometric mean titers for rabies antibodies were lower with teriflunomide at days 31 and 38 than with placebo. However, all subjects achieved sufficient seroprotection following rabies vaccination (titers well above the 0.5 IU/mL threshold). Overall, the DTH response to recall antigens in the teriflunomide group did not notably differ from responses in the placebo group. Conclusions: Following vaccination, geometric mean titers for rabies antibodies were lower with teriflunomide than with placebo. However, teriflunomide did not limit the ability to achieve seroprotective titers against this neoantigen. Evaluation of DTH showed that teriflunomide had no adverse impact on the cellular memory response to recall antigens. Classification of evidence: This study provides Class II evidence that in normal subjects treated with teriflunomide, antibody titer responses to rabies vaccination are lower than with placebo but sufficient for seroprotection.

The voltammetric characteristics of polycrystalline Au and W electrodes cleaned (thermal annealing at 1100 K) and characterized (Auger electron spectroscopy) in ultrahigh vacuum (UHV) have been examined in ultrapure AlCl 3 /1-ethyl-3-methylimidazolium chloride (EtMeImCl) melts in UHV. These experiments were performed using a custom-designed transfer system that allows for the all-Al electrochemical cell to be filled with EtMeImCl in an auxiliary UHV chamber and later transferred under UHV to the main UHV chamber that houses the Auger electron spectrometer. The results obtained for the underpotential (UPD) and bulk deposition of Al on Au were found to be very similar to those reported in the literature for measurements carried out under 1 atm of an inert gas in a glovebox. For the far more reactive W surfaces, voltammetric features ascribed to the stripping of underpotential-deposited Al could be observed following a single scan from 1.0 V vs Al 3 + /Al to a potential negative enough for bulk deposition of Al to ensue. This behavior is unlike that reported in the literature for experiments performed in a glovebox, which required either extensive potential cycling in the Al bulk deposition and stripping region or excursions to potentials positive enough for chlorine evolution to ensue for Al UPD features to be clearly discerned. These observations open new prospects for fundamental electrochemical studies of well-characterized, highly reactive metals, including single crystals, in a variety of low vapor pressure ionic liquids.

We demonstrate a polarization‐insensitive optical bandpass filter in indium phosphide (InP) with a 3 dB bandwidth of 1.5 nm at a center wavelength of 1.498 μm. The 5‐mm‐long filter is based on a grating‐assisted vertical directional coupler and features a novel double‐periodic coupling grating.

We demonstrate lasing in InGaAsP (1.3 /spl mu/m) vertical cavity lasers employing GaAs/AlAs mirrors on a GaAs substrate. The lasers operate pulsed at 300 K with a threshold current of 9 mA and they operate continuous wave at temperatures as high as 230 K. >

We describe the idea behind strain compensation and how it is important for high quality lasers and amplifiers. Examples of compensated and uncompensated structures are compared in X-ray rocking curves, photoluminescence, and lasing properties. The unique properties of devices which use strain compensated compressive and/or tensile wells are described, such as wide band tunable lasers, large bandwidth amplifiers, and polarization independent amplifiers. >

Highly nondegenerate four-wave mixing was investigated in a 1.5 µm compressively strained multi-quantum-well semiconductor traveling-wave optical amplifier at detuning frequencies up to 600 GHz. A gain nonlinearity with a characteristic relaxation time of 650 fs was determined from the data, and the nonlinear gain coefficient was estimated to be 4.3×10^–23 m^3. Dynamic carrier heating is believed to be the major source of nonlinear gain in this device at the wavelengths investigated.

A tensile-strained InGaAsP/InP multi-quantum-well optical amplifier is constructed which has >or=92 nm bandwidth at 16-dB gain for 50-mA drive current. The wide gain bandwidth is a result of both n=1 and n=2 contributions from the e to 1h transition. These results suggest wide tunability for lasers made from this material. >

A multiquantum-well optical amplifier for 1.5- mu m wavelength operation using alternating tensile and compressively strained wells in the active region is described. For each bias level measured, the polarization sensitivity of the amplifier gain is 1 dB or less averaged over the gain bandwidth. This amplifier is suitable for integration with other optical devices in photonic integrated circuits which require polarization-independent gain. >

A waveguide lens is a key component for integrated optics. Extensive work in glass and LiNbO3 materials has been reported on the subject. However, a semiconductor material such as InP is more advantageous for optical-communications applications because both passive and active (lasers, amplifiers, detectors) components working at 1.55 µm can be integrated on the same chip. Although some work has been reported in GaAs,1,2 very little has been published for InP. A practical lens for photonic integrated circuits (PIC’s) should collimate (focus) the light originating from (coupling into) a waveguide. Typically, this requires an aperture of at least f/5 to accommodate the divergence of the output light from a waveguide, and it requires a focused spot size of a few micrometers to optimize coupling into a fiber or a waveguide. Insertion loss should also be kept low. Here, we report an integrated lens formed by two aspheric surfaces that meets these requirements and uses a simple wet- etch processing technique.

An InP based 1×16 optical switch is demonstrated. The sixteen output ports are spaced 250 μm apart, and the total device length is 5.9 mm. Optical amplifiers are used to gate the optical signals and to provide optical gain. The total loss of the device, excluding coupling, is less than 2.5 dB and loss free operation was observed at low input powers. The output extinction ratios are lower than 18 dB and the uniformity spread of the sixteen channels is as low as 6.7 dB.

We demonstrate that phosphorous ion implantation in InGaAs/InP quantum wells can be used to produce large (from 1550 to 1200 nm) blueshifts of the band edge. This reproducible technique of lateral band‐gap control can be used in quantum‐well photonic integrated circuits to produce regions of low‐loss waveguide, e.g., for interconnects or large passive cavities. Phosphorous implants with subsequent p‐type InP regrowth produces blueshifted quantum‐well diodes with good reverse‐bias characteristics and low‐loss p‐i(multiple quantum well)‐n waveguides.

A 5.5-mm-long monolithic extended-cavity laser with an integrated Bragg-reflector in the InGaAsP system for active mode-locking at low repetition rates at a wavelength of 1.55 mu m has been fabricated. The device, which is designed to be used as a pulse source in long-distance soliton systems and optical time-division multiplexed systems, generates 20-ps-wide transform-limited pulses with a time-bandwidth product of 0.34 at a repetition rate of 8.1 GHz. >

MOVPE-grown InGaAs/GaAs strained-layered lasers emitting at 0.98 mu m have been fabricated using InGaAsP as an alternative to AlGaAs in the cladding layers. Semi-insulating blocked planar buried heterostructure lasers 2.5 mu m wide have thresholds as low as 8 mA for 350 mu m long devices. With the addition of reflective coatings, slope efficiencies of 0.67 mW/mA and output powers of 60 mW at 160 mA have been obtained. >

The carrier capture times in multiple quantum well semiconductor amplifiers of different structures are studied under high plasma density conditions. Fast (

A scheme for selective electroless copper patterning of Si wafers has been developed with palladium silicide as the catalytic layer initiating copper deposition. Thermal conversion of a palladium layer to silicides on a SiO2 patterned silicon substrate, followed by an acid etching of the unreacted palladium on the SiO2 surfaces, leaves only the silicided regions at the base of the windows for electroless copper deposition. Excellent via‐filling down to 0.5‐μm dimensions and an aspect ratio of 6 has been demonstrated. The thin copper deposited on the Pd2Si has a resistivity of ∼2.0 μΩ cm. Contactless photocarrier decay measurements indicate virtually no degradation of Si lifetimes by these processing steps.

THE recent syntheses1,2 of macroscopic quantities of C60 have suggested possible applications in host–guest and organic chemistry, tribology, electrochemistry and semiconductor tech-nology. Here we report the preparation of alkali-metal-doped films of C60 and C70 which have electrical conductivities at room temperature that are comparable to those attained by n-type doped polyacetylene. The highest conductivities observed in the doped films are: 4Scm−1 (Cs/C60), 100 (Rb/C60), 500 (K/C60), 20 (Na/C60), 10 (Li/C60), 2 (K/C70). The doping process is reversed on exposure of the films to the atmosphere. At high doping levels, the films become more resistive. We attribute the conductivity induced in these films to the formation of energy bands from the π orbitals of C60 or C70, which become partially filled with carriers on doping. The smaller alkali metal ions should be able to fit into the interstices in the lattice without disrupting the network of contacts between the carbon spheroids. In the case of C60, this would allow the development of an isotropic band structure, and we therefore propose that these materials may constitute the first three-dimensional 'organic' conductors.

We observe saturation in the electroabsorption of InGaAs/InP multiple quantum wells (MQWs) at high optical intensity. Contrary to the mechanism for zero‐field MQWs, we find that saturation occurs due to the presence of trapped photogenerated holes that screen the MQWs from the applied electric field. By carefully measuring the absorption coefficient of the wells and the emission time for holes, we are able to fit the observed electroabsorption saturation with no adjustable parameters.

Using bulk InGaAsP as a saturable absorber we have passively mode locked a NaCl color center laser to produce transform‐limited, pedestal‐free pulses near 1.6 μm as short as 197 fs with up to 4.2 kW peak power. Our results simplify the saturable absorber material requirements and prove that excitons are not required for generating subpicosecond pulses. By comparing a dozen samples we find that a minimum band‐edge absorbance of 40% is required to generate subpicosecond pulses, although details of the band edge are not critical. In addition, we find stable mode locking always occurs on the long‐wavelength side of the laser gain peak.

A rhenium solar-thermal receiver/absorber propulsion (STRAP) device has been designed and fabricated. Its uniqueness lies in its simplicity of design and fabrication, consisting of just three components electron beam welded together: a rhenium foam heat exchanger between inner and outer rhenium structural shells, with the thrust chamber integral to the outer shell. Plans have been developed for testing this device at the Air Force Phillips Laboratory.

Anticoagulant andanti-platelet effectsare maintained following coadministration of otamixaban, adirect factor Xa inhibitor, with tirofiban in healthy volunteers

We demonstrate greater than 90% quantum efficiency in an In/sub 0.53/Ga/sub 0.47/As photodetector with a thin (900 /spl Aring/) absorbing layer. This was achieved by inserting the In/sub 0.53/Ga/sub 0.47/As/InP epitaxial layer into a microcavity composed of a GaAs/AlAs quarter-wavelength stack (QWS) and a Si/SiO/sub 2/ dielectric mirror. The 900-/spl Aring/-thick In/sub 0.53/Ga/sub 0.47/As layer was wafer fused to a GaAs/AlAs mirror, having nearly 100% power reflectivity. A Si/SiO/sub 2/ dielectric mirror was subsequently deposited onto the wafer-fused photodiode to form an asymmetric Fabry-Perot cavity. The external quantum efficiency and absorption bandwidth for the wafer-fused RCE photodiodes were measured to be 94/spl plusmn/3% and 14 nm, respectively. To our knowledge, these wafer-fused RCE photodetectors have the highest external quantum efficiency and narrowest absorption bandwidth ever reported on the long-wavelength resonant-cavity-enhanced photodetectors. >

A dual back-illuminated photodetector for balanced coherent receivers applications is presented. The photodetectors have an InP/InGaAs/InP p-i-n structure. Several additional semiconductor layers have been added to fabricate the structure by selective wet etching. The material was grown by metalorganic vapor phase epitaxy (MOVPE) on a semiinsulating, Fe doped, InP substrate. The passivation and the insulation between contacts were obtained using polyimide. The contact structure is intended to connect the photodetector to the package by flip-chip. The measured photodetector capacitance was around 0.2 pF for a single photodetector (without series connection), the series resistance under 20 ohms, and the dark current under 10 nA.

Room-temperature pulsed operation of InGaAsP (1.3 mu m)/InP vertical cavity surface emitting lasers has been achieved with threshold current as low as 50 mA using a constricted-mesa structure with dielectric mirrors. Above-room-temperature operation has also been realized with a maximum operation temperature of 66 degrees C. Pulsed and continuous-wave threshold currents at 77 K are 1.5 and 3.9 mA, respectively. >

Summary form only given. The observation of above-room-temperature pulsed operation of 1.3- mu m InGaAsP/InP vertical-cavity surface emitting lasers (VCSELs) is reported. Lasing operation was successfully achieved up to temperatures as high as 66 degrees C. The threshold current at 20 degrees C was only 50 mA, which is much lower than that previously reported (150 mA) for VCSELs in this material system. The VCSEL structure is the polyimide-embedded constricted mesa structure with an undercut active layer formed using a selective chemical etchant. The laser cavity consists of a 1.5- mu m-thick p-InP cladding layer, a 0.6- mu m p-InGaAsP active layer, and a 2- mu m n-InP cladding layer grown by MOVPE on a p-type InP substrate. >

Measurements of the flux of copper species reaching the ring electrode of a rotating Nd2CuO4−xFx disk-gold ring electrode configuration in acidified chloride solutions allow for the real-time analysis of x as the superconductor is etched. The method is based on analyzing the ratio of copper oxidation states arising from the open circuit dissolution reaction of the Nd2CuO4−xFx disk into chloride solutions. Through voltammetry at the gold ring electrode, the Cu2+ and Cu1+ products are measured quantitatively and x determined. For specimens showing a 27 K onset of Tc, the average copper oxidation state is 1.74, corresponding to the stoichiometry Nd2CuO3.74F0.26. Superconductor electrode potentials are determined directly by the Cu2+/Cu1+ ratios.

It has been shown that bulk layers of InGaAs and InGaAsP grown using tertiarybutylarsine (TBA) have nearly as good electrical and optical properties as AsH/sub 3/-grown layers. As a consequence conventional InGaAsP lasers at 1.3 mu m were grown by TBA and were found to have properties as good as those of AsH/sub 3/ lasers. Investigations into other components of PIC circuits grown by using TBA as substitute for AsH/sub 3/ are presented. Studies of multi-quantum-well (MQW) and strained-layer MQW lasers, a four-port directional coupler optical switch, and quantum-confined Stark effect modulator structures grown by this technique are reported. The components are intended for use in photonic integrated circuits. In all cases satisfactory performance is demonstrated. >