Search

Summary Ninety-one patients with poor prognosis non-seminomatous germ cell tumours (NSGCT) were treated with an initial intensive chemotherapy schedule. Suitable patients fulfilled one or more of the following criteria: lymph node metastases greater than 10 cm diameter; liver, brain or bone metastases; serum HCG level greater than 50 000 IU/L; and extragonadal primary tumours. Treatment consisted of 3 cycles of bleomycin, vin-cristine and cisplatin (BOP) administered at 10 day intervals, followed by 3 cycles of etoposide, ifosfamide and cisplatin (VIP) at 21 day intervals. A total of 64 patients (70%) achieved a complete remission. This comprised 46 patients who received BOP/VIP only, and 18 patients who received additional chemotherapy after BOP ATP. Of these 64 patients, 51 underwent complete surgical resection of residual masses, including 11 in whom there was evidence of teratoma with cellular atypia or non-germ cell cancer in the resected tissue. A further 9 patients had persisting unresected radiological masses in the presence of marker complete remission. The overall response rate was 80%. Currently 57 patients (63%) remain alive and free from disease progression. The median follow-up period is 90 weeks (range 24–206 weeks), with a 2 yr actuarial progression-free survival of 66% (95% c.i. 55–77%). Major toxicity was myelosuppression, occurring during the VIP arm of therapy, with a median nadir WBC of 1.1 × 109/L and median platelet count of 51 × 109/L. Other toxicity included peripheral neuropathy (WHO Grade 2 and 3 in 22%). We conclude that treatment results with the BOP/VIP schedule in this poor prognosis patient group are at least comparable with other schedules, and toxicity is manageable. A randomised prospective trial comparing BOP/VIP with standard therapy using BEP (bleomycin, etoposide, cisplatin) has now opened to assess whether an advantage can be shown for the initial intensive therapy.

Breast conservation therapy (BCT) is recommended as standard management of early breast cancer. The aim of this study was to retrospectively evaluate the results of BCT to identify prognostic factors predictive of treatment outcomes.Four hundred and ninety-eight eligible women with unilateral stage I-II breast cancer who had undergone BCT were analyzed.The cumulative incidence of local recurrence (LR) was 1.9% and 3.7% at 3- and 5-years respectively. The 5-year disease-free, cancer-specific, and overall survival (DFS, CSS, OS) were 80.0%, 87.3% and 85.4% respectively. Significant independent predictors for LR included young age and absence of chemotherapy. Regional nodal radiotherapy was significantly associated with improved DFS and OS.Our results confirmed the efficacy of BCT in the treatment of early breast cancer and indicated that inclusion of regional nodal areas within the radiotherapy field might be beneficial in the BCT setting, particularly for patients with adverse risk features.

The aim of this study was to determine the maximum tolerated dose of a fixed dose of docetaxel when combined with continuous infusion ifosfamide, with and without G-CSF support, in the treatment of advanced cancer, and to evaluate anti-tumour activity of this combination. Thirty-one patients with advanced malignancies were treated with docetaxel 75 mg/m2 intravenously on days 1, and ifosfamide at increasing dose levels from 1500 mg/m2/day to 2750 mg/m2/day as a continuous infusion from day 1–3, every 3 weeks. A total of 107 cycles of treatment were administered. Without G-CSF support dose-limiting toxicity of grade 4 neutropenia greater than 5 days duration occurred at dose level 1. With the addition of G-CSF the maximum tolerated dose was docetaxel 75 mg/m2 on day 1 and ifosfamide 2750 mg/m2/day on days 1–3. Dose limiting toxicity (DLT) included ifosfamide-induced encephalopathy, febrile neutropenia and grade three mucositis. Three complete responses and 3 partial responses were seen. This combination of docetaxel and infusional ifosfamide is feasible and effective. The recommended dose for future phase II studies is docetaxel 75 mg/m2 on day 1 and ifosfamide 2500 mg/m2/day continuous infusion on days 1–3. British Journal of Cancer (2002) 87, 846–849. doi:10.1038/sj.bjc.6600542 www.bjcancer.com © 2002 Cancer Research UK

The threat of bioterrorism in the United States is increasing. Health professionals, especially "front-line" practitioners, must be able to recognize the potential for major impacts from a bioterrorism event. Although an effective attack could produce numbers of casualties equivalent to those resulting from a nuclear weapon, an unannounced attack would be unlikely to be recognized immediately. Health workers may be the first to recognize an attack. However, only limited assistance is available to aid local community medical organizations in planning for bioterrorism. Military medical personnel have had more experience in planning for terrorist activities than many of their civilian colleagues. Their experience may be invaluable to local civilian treatment facilities in developing practical plans to meet the unique aspects of bioterrorism. In addition to considering agent-specific medical problems and requirements, it is particularly important for plans to address command and control, communication, and coordination if the resultant response is to be effective.

The oral bacterium Streptococcus mutans possesses the ability to ferment a wide range of carbohydrates, which results in the production of acids that can cause demineralisation of tooth enamel and subsequent dental caries. However, it has been shown that approximately 11% of independent isolates of S. mutans from around the world lack the ability to ferment melibiose, raffinose, and on occasion β-glucosides (1,4). This is due to a deletion which extends through a region of the genome that includes the multiple sugar metabolism (msm) operon involved in the uptake and metabolism of a number of sugars (3). The msm region has been reintroduced to the deletion mutants by transformation and the ability to grow on galactose and β-glucosides was also restored, showing the linkage of the respective genes. The extent of the deletion is further being investigated with the use of pulsed field gel electrophoresis and Southern hybridizations with known S. mutans genes as probes.

Serum oestradiol and progesterone concentrations were measured at weekly intervals for six months, and correlated with daily behavioural observations in two adult female snow leopards (Panthera uncia). Three oestradiol peaks (> 21 pg ml-1; interval 3.6 weeks) were identified in a snow leopardess housed alone (two more were probably missed because of the weekly sampling schedule), and three oestradiol peaks were identified in a snow leopardess housed with a male as a breeding pair (interval 6 weeks). Daily frequencies of feline reproductive behaviour averaged 1.77 observations per observation period during weeks of high oestradiol and 0.62 during weeks of low oestradiol. Progesterone concentrations did not rise above baseline values (< 2 ng ml-1) in the isolated animal, but 6 weeks of high progesterone concentrations (4.9-38.8 ng ml-1) was recorded in the paired snow leopardess following mating. No offspring were produced. Snow leopards were observed daily for an additional 4.5 years. Sexual behaviour peaks could be clearly identified from December through April, and average daily sexual behaviour scores were higher during these months than during the rest of the year. Intervals between sexual behaviour peaks for the isolated snow leopardess averaged 3.03 weeks. The sexual behaviour of the paired snow leopards decreased for 8-9 weeks following mating when no offspring were produced, and decreased for 13 weeks in one year when a single cub was born.

e11554 Background: Breast cancer is a heterogeneous disease encompassing entities with distinct biological characteristics and clinical course. Triple-negative disease (TND) is clinically aggressive disease with limited effective therapy. We compare the clinico- pathologic characteristics, recurrence and survival rates of patients with TND and non-TND. Methods: The POWH Cancer Centre breast cancer database was retrospectively reviewed from January 1995 to December 2005. 1254 eligible women with breast cancer undergoing definitive primary breast surgery were identified. TND was defined as ER-, PR- and HER2 0 or 1+ by IHC and / or florescent in- situ hybridization (FISH) negative. Non-TND was defined as either ER+ and / or PR+ and/or HER2+. Further comparisons of survival outcomes were analyzed in a subgroup of 785 patients subdivided into three groups: ER+ and/or PR+ and HER2-, HER2+ and TND. Results: There were 135 patients (10.8%) with TND. TND tumours were characterized by larger size (p=0.02), histological grade 3 (p No significant financial relationships to disclose.

5016 Background: We performed a multicentre randomised trial for good-prognosis germ-cell tumours of two standard chemotherapy regimens containing bleomycin (B), etoposide (E) and cisplatin (P). Accrual was stopped early, after interim analysis with a median follow-up of 33 months found a survival benefit for the regimen similar to Indiana University BEP, compared with the less dose-intense regimen (Toner, Lancet 2001). Here we report on long-term outcomes and patterns of relapse. Methods: Patients with a good prognosis defined by modified Memorial Sloan-Kettering criteria were randomised to 3B90E500P (3 cycles every 21 days of B 30 kU on days 1, 8 and 15, E 100 mg/m2 on days 1–5, and P 20 mg/m2 on days 1–5); or 4B30E360P (4 cycles every 21 days of B 30 kU on day 1, E 120 mg/m2 on days 1–3, and P 100 mg/m2 on day 1). Overall survival was the primary endpoint. Progression-free survival (PFS) was a secondary endpoint. All analyses were by intention-to-treat and with 2-sided p-values. Results: 166 patients were randomised, 83 to each regimen. Median follow-up is now 8.5 years and all but 5 have been followed ≥ 5 years. Overall survival remains substantially better with 3B90E500P than 4B30E360P (8YS 92% vs 83%, hazard ratio 0.38, 95% CI 0.15 to 0.97, p=0.037), and remains significant when analyses were restricted to 138 patients with good prognosis by IGCCCG criteria (p=0.035). Trends for PFS favour 3B90E500P but are not statistically significant (8YPFS 86% vs 79%, hazard ratio 0.6, 95% CI 0.3 to 1.1, p=0.15). 7 of 15 relapses occurring within 2 years after randomisation were fatal, but all 4 relapses occurring > 2 years after randomisation were fatal. Conclusions: The survival benefit of 3B90E500P compared to 4B30E360P was maintained with long-term follow-up. The occurrence of relapses beyond 2 years affirms the importance of long-term follow-up. Late relapses in this study were associated with uniformly poor outcomes. [Table: see text] No significant financial relationships to disclose.

10665 Background: MBC pts have often already received, or are inappropriate for, anthracyclines and taxanes. 5-Fluorouracil and vinorelbine is an active, well tolerated combination regimen. Capecitabine (C), a fluoropyrimidine carbamate derivative, has the advantage of oral administration. The aim of this study is to determine the efficacy and safety of C and iv vinorelbine (V) in pts with MBC. Methods: Between May 2003-June 2005 21pts with pretreated MBC, maximum of 1 prior metastatic regimen, received C 1000mg/m2 bd day 1–14 and V 25 mg/m2 iv d1+ d8 q21 days. All pts had measurable disease (RECIST), baseline KPS ≥ 80% and adequate baseline organ function. The primary endpoint was response; secondary endpoints were time to progression (TTP), duration of response, survival and safety. Results: Median age was 56 years (range 38–73); median KPS 90%. All pts had received anthracyclines and 62% taxanes. 20pts were evaluable for response and 21 for toxicity. Objective responses were seen in 7/20 (35%) (95% CI 18–57%), including 2 CR, and stable disease (SD) in 4/20 (20%) (95% CI 8–42%). Median duration of response was 6.9 mths (95% CI 4.7–13.1); TTP 5.8 mths (95% CI 2.8–6.8) and survival 12.2 mths (95% CI 8.7–15.7), with a median followup of 12.2 mths. The main toxicity was haematological with 15 episodes of G3 and one G4 neutropenia in 10 pts and 1 pt respectively and 2 episodes of G3 febrile neutropenia in 1 pt. Other G3 toxicities included diarrhoea, fatigue and hypokaleamia in 2 pts each and headache, anorexia, stomatitis, dehydration, and peripheral neuropathy in 1 pt each. There were no other G4 toxicities or treatment related deaths. The median dose intensity of C was 7941mg/m2/wk (85% of intended, range 51–102%) and for V 12.4 mg/m2/wk (75% of intended, range 48–100%). Conclusion: The combination of capecitabine and iv vinorelbine is active and generally well tolerated in pts with pretreated MBC. The recent availability of oral vinorelbine provides an opportunity to explore a fully oral combination chemotherapy regimen for pts with MBC. [Table: see text]

8032 Background: Adjuvant analgesic treatments have primary indications for uses other than the treatment of pain but demonstrate analgesic activity in some conditions. Although there is high level...

Three mature nulliparous female leopards were studied for 5 years. During three separate 6-month periods serum oestradiol and progesterone concentrations were measured at weekly intervals. Oestradiol was elevated over 21 pg/ml for 54 weeks during these 3 periods, and 36 oestradiol peaks (65.8 +/- 6.3 pg/ml (mean +/- s.e.m.), range 21-172 pg/ml) were identified. Daily frequency of feline reproductive behaviours averaged over each week increased from 1.9 +/- 0.2 (n = 93) during weeks with low serum oestradiol concentrations (less than 21 pg/ml) to 5.3 +/- 0.6 (n = 54) during weeks when serum oestradiol concentrations (greater than 21 pg/ml) were high. Increased serum progesterone concentrations (13-98 n/gml) were observed on 5 occasions in 2 leopards housed together. These presumptive luteal phases lasted from 1 to 5 weeks. Baseline progesterone values were 1.6 +/- 0.4 ng/ml (n = 131). No progesterone increments were observed in isolated animals, and serum concentrations remained at baseline levels. These limited observations suggest that female leopards do not require intromission to induce ovulation and luteal function. The average interval between oestradiol peaks for cycles with no progesterone increment was 3.4 weeks (range 1-6 weeks). The interval for the 3 complete cycles associated with elevated progesterone concentrations was 7.3 weeks. Analysis of sexual behaviours over the 5-year study period revealed no evidence of seasonality in these captive leopards.

High-quality AlxGa1-xAs with a bandgap of 1.93 eV has been grown using metalorganic chemical vapor deposition (MOCVD). Levels exceeding 1018 cm-3 can be obtained for Se, Si and Zn dopants. In particular, incorporation of the re-type dopants at this bandgap is not appreciably less efficient than in lower-bandgap AlxGa1-xAs. The best material, as measured by photoluminescence intensity, is obtained using high V/III ratios (40 forp-type material and as high as 60 forn- type and low growth rates (300 A/min). Purification of the arsine in situ with an Al/Ga/In eutectic bubbler to remove trace water and oxygen impurities is found to be essential for the growth of high-quality material, as indicated by photoluminescence intensity measurements. Solar cells fabricated from such material exhibit efficiencies as high as 12.1% under one-sun, airmass zero (AMO) conditions, with an open-circuit voltage of 1.38 V, short-circuit current density of 14.1 mA/cm2, and fill factor of 0.84.

The first application of MOCVD compositional grading by means of substrate temperature changes is reported for the case of GaAs−Px (0 ≤ x ≤ 0.30). The method is based upon the higher pyrolysis efficiency ratio of AsH3 relative to PH3 at lower growth temperatures. The growth upon GaAs substrates commences at a temperature at which this PH3/ASH3 thermal cracking efficiency ratio is extremely high; raising the growth temperature decreases this ratio, and hence the As/P ratio in the solid. GaAs1−xPx epilayers grown on GaAs by this method display excellent materials properties and are virtually optically and electrically indistinguishable from conventionally-graded epilayers in which the gas phase mole fractions of transport agents are varied at constant temperature. The method is applicable to systems where temperature-dependent cracking efficiency differentials exist.

Absorption data on strained GaAs1−xPx-GaAs superlattices (SL, 128-period, barrier size LB≈75 A, quantum-well size Lz≈75 A, alloy composition x≈0.25) are presented in the range 0–10 kbars. The absorption curves obtained show no exciton show no exciton peaks such as seen in lattice- matched AlxGa1−xAs-GaAs SL's, and the pressure coefficient decreases from 11.5 meV/kbar to ≈ 10.5 meV/kbar in the wells and ≈6.5 meV/kbar at energies approaching and above the barrier energies. This behavior is attributed to the fluctuations in strain caused by the alloy disorder, and clustering, of the barriers.

Magnesium-doped GaAs has been grown by organometallic vapor phase epitaxy (OM-VPE). Bis (cyclopentadienyl) mag-nesium (Cp2Mg) is used as the organometallic precursor to Mg. The epitaxial layers have been characterized by resis-tivity and Hall measurements, photoluminescence spectro-scopy and optical microscopy. The material is of high electrical and optical quality; controllable doping over the range 1015 to 1019cm-3 is reproducibly attained. The ionization energy of the Mg acceptor is determined to be 30 ± 2.5 meV at 77K. Negligible compensation is observed, consistent with clean thermolysis of the Cp2Mg under growth conditions. GaAs diodes have been fabricated using Mg as the p-dopant and either Se, Si, or Sn as the n-dopant. The diodes show very low leakage currents under reverse bias, even at relatively high doping levels. Degenerately-doped junctions for interconnecting monolithic cascade concentrator solar cells have also been successfully grown, displaying forward conductivities as high as 19 amps V−1 cm-2 at 0.05V forward bias.

A chemical vapor deposition “memory effect” is the tendency of a source material to adsorb onto the internal walls of the system and subsequently desorb after nominal source shutoff. H2Se, the most common Se transport agent in metalorganic chemical vapor deposition (MOCVD), adsorbs onto stainless steel and glass surfaces. Among the consequences are: graded doping profiles at the end of Se-containing epitaxial layers and the depletion of H2Se gas mixtures with time. By contrast, SiH4, the most common Si transport agent, exhibits negligible memory effect and is recommended as an alternate n-dopant source when memory effects must be entirely eliminated. Capacitance-voltage measurements are used to quantify the extent of the t2Se “memory effect” in GaAs to identify methods for its reduction or elimination, and to distinguish the effects of diffusion and memory upon observed doping profiles. Memory effects are also anticipated when Se is a primary constituent of a semiconductor and H2Se the transport agent.

Power conversion efficiencies as high as 16.5% under 1 Sun, air mass 1.5 (AM 1.5) illumination have been obtained for three-terminal, two-junction 1.72 eV AlGaAs/1.15 eV GaInAs monolithic cascade solar cells. The structures were grown by metal-organic chemical vapor deposition. The increased efficiencies arise primarily from improved surface morphology in this lattice-mismatched materials system. For the individual subcells in a cascade configuration, 1 Sun, Am 1.5 efficiencies as high as 10.4% and 15.3% are obtained for 1.15 eV GaInAs and 1.72 eV AlGaAs, projecting an eventual efficiency of 25.7% for the corresponding two-junction stack. Under 400 Sun concentration, these values are projected to increase to 12%, 19% and 31% respectively. In the lattice-matched 1.72 eV AlGaAs/1.42 eV GaAs materials system, the surface morphology has proved easier to optimize. Two-junction, two-terminal cascades in which the subcells are electrically connected by high-conductance junctions have been fabricated. Open-circuit voltages Voc as high as 2.01 V and fill factors as high as 0.86 have been obtained. These fill factors, comparable with those observed for the best single-junction cells under 1 Sun, AM 1.5 conditions, demonstrate the low residual resistance of the high-conductance junction.

Efficient two-junction monolithic cascade solar cells (AlGaAs/GaInAs and AlGaAs/GaAs) were grown by metal-organic chemical vapor deposition (MOCVD) in two-terminal and three-terminal configurations. Owing to the complexity of the structures, the reproducible attainment of good efficiencies depends heavily on the compatibility of the growth and/or processing conditions of the components, including the subcells, compositionally graded layers and subcell electrical interconnection. Recent modifications of the MOCVD deposition conditions have been found to favor such compatibility and hence permit the fabrication of efficient cascades. Both metal-interconnect technology and tunnel-junction technology have been successful.

Multiple grading layers and transparent grading layers have been developed to permit the crystallographic connection of the individual subcells of a monolithic cascade solar cell, which are lattice mismatched with respect to each other. The transparent grading is of sufficiently high bandgap to absorb a negligible fraction of the light destined for underlying subcells. High-quality subcells can be grown by this double mismatch technique in which changes of lattice constant occur not only between the substrate and lower cell, but also between the lower and upper cells.

Stimulated emission data are presented on a large variety of strained‐layer quantum‐well heterostructures (QWH’s) and superlattices (SL’s) grown by metalorganic chemical vapor deposition (MOCVD). These structures consist of barrier‐well combinations of thickness LB,Lz ≲150 A made from GaAs‐InGaAs, GaAsP‐GaAs, and GaAsP‐InGaAs. Also employed are higher band‐gap confining layers of InxAlyGa1‐x‐yAs, AlyGa1−yAs1−xPx, and AlxGa1−xAs. All of the heterostructures are grown on a GaAs substrate with and, in some cases, without a graded layer. The strain range between 0.2 to 12.5×10−3 is examined. Photopumped, these heterostructures operate as continuous (cw) 300 K lasers, with thresholds of 1.6–7.5×103 W/cm2, for periods of time between 0.5 to >35 min. Under high‐level excitation, the equivalent of Jeq∼103 A/cm2, laser operation fails or is quenched by networks of dislocations (with 〈110〉 Burger’s vectors) that are generated within the strained‐layer region of the QWH’s or SL’s. These dislocation networks, which a...

An experiment was performed in order to determine the magnitude of that portion of dry, kinetic friction which is contributed by Coulomb friction, or the mechanical interlocking of surface irregularities. The results indicate that the work of the mechanical component of friction accounts for only a few percent of the work of total measured friction.

This paper considers theoretically the propagation of compressional waves in a structure consisting of an infinite series of alternating layers of two different media which may be either fluid or solid. It is shown that such a structure acts as a low‐pass acoustic filter. A number of special cases are computed and it is found that the cut‐off frequency depends essentially on the section length and the relative acoustic impedance of the media. The problem is shown to be mathematically quite analogous to that of the propagation of acoustic waves in air through an infinite tube containing alternate constrictions and expansions. Moreover the loaded solid filter considered in a previous paper by Lindsay and White proves to be a limiting case of the non‐homogeneous medium filter of the present article.

Experimental observation of resonant tunneling in a strained-layer double-barrier, single-well GaAs1−xPx-GaAs (x ≈ 0.3) quantum-well heterostructure (QWH) is reported. Tunneling via quasi-two-dimensional states in the center GaAs quantum well is confirmed by anisotropy of the d2IdV2 characteristic in a strong perpendicular magnetic field (B∥) as compared to a parallel field (BB⊃. Transmission electron microscopy is used to show the effect of dislocations in introducing asymmetry in the tunneling I-V characteristics.

A novel time‐of‐flight technique has been developed for simultaneously measuring minority‐carrier lifetime and diffusivity in homojunctions. A pulsed dye laser produces electron‐hole pairs near the front surface of the device. A delay occurs before the onset of photocurrent due to the diffusion transit time of minority carriers to the junction. An analysis of this effect by both a simplified analytical model and a computer simulation gives similar results for the current as a function of time. A fit of the theory to experimental data on Al0.25Ga0.75As n/p homojunctions produces minority‐carrier lifetime, diffusivity, and diffusion length.

Data are presented showing that Zn diffusion into a strained GaP‐GaAs1−xPx (x∼0.6) superlattice (40 periods, Lz∼120 A GaAsP quantum wells, LB∼120 A GaP barriers) enhances the interdiffusion of As and P (anion interchange) at the heteriointerfaces, thus resulting in disordered indirect gap bulk crystal GaAs1−xPx (x∼0.8).

Magnesium has been substituted for zinc in GaAs and Ga(0.75)In(0.25)As solar cells grown by metalorganic chemical vapor deposition (MOCVD). Bis(cyclopentadienyl)magnesium (Cp2Mg) is used as the MOCVD transport agent for Mg. Full retention of excellent material quality and efficient cell performance results. The substitution of Mg for Zn would enhance the abruptness and reproducibility of doping profiles, and facilitate high temperature processing and operation, due to the much lower diffusion coefficient of Mg, relative to Zn, in these materials.

Photoluminescence data are presented on a direct‐well GaAs1−xPx‐GaAs (x∼0.25) strained superlattice (SL) (barrier LB ∼75 A, quantum well Lz∼75 A) and on indirect‐well GaP‐GaAs1−xPx (x∼0.6) strained SL’s (LB, Lz∼120 A and LB, Lz∼60 A) grown by organometallic vapor phase epitaxy. Stimulated emission (at 300 and at 77 K) is observed in the former but only weak luminescence in the latter, thus establishing that a large density of defects at the heterointerfaces is not necessarily an issue in strained SL’s and that so far zone‐folding effects, and SL ‘‘indirect‐direct’’ conversion, have not been observed in indirect systems.

Continuous (cw) 300‐K laser operation of a 66‐period lower energy GaAs‐InxGa1−xAs (x∼0.2) strained superlattice (SL) and a higher energy 128‐period GaAs1−xPx‐GaAs (x∼0.25) strained SL is demonstrated. The strained SL’s are grown by organometallic vapor phase epitaxy (OMVPE) or metalorganic chemical vapor deposition (MOCVD) with higher gap quaternary confining layers and LB ∼75 A barriers and Lz ∼75 A quantum wells. These SL’s are unstable during high level excitation, failing in 2–20 min when operated cw at 300 K as photopumped lasers.

The accommodation of lattice mismatch in strained‐layer GaAs‐InxGa1−xAs (x≊0.27) superlattices grown by metalorganic chemical vapor deposition has been examined as a function of layer thickness using transmission electron microscopy. The degree of distortion from cubic is shown to be dependent on the layer thickness and at sufficiently large layer sizes (≳180 A) dislocations are introduced at the interfaces.

Efficient two-junction monolithic cascade solar cells have been fabricated in two dif-ferent III-V materials systems. The cells are grown by metalorganic chemical vapor deposi-tion (MOCVD). Two-junction efficiencies as high as 25% (1-sun, AM2) are projected from the individual GaInAs (1.15 eV) and A1GaAs (1.72 to 1.75 eV) subcell efficiencies obtained in a cascade configuration. Factors influencing actual cascade efficiency and reproducibility are discussed. Metal interconnection of the AlGaAs and GaInAs subcells during post-growth processing yields two-terminal cascades with power conversion efficiencies (n) as high as 13.6% at 1-sun, airmass two (AM2) , and 11.1% at 1-sun, airmass zero (AMO). Three-terminal AlGaAs (1.72 eV)/GaInAs (1.15 eV) cascades have shown 11 of 12.6% (1-sun, AMO). Alternatively, insertion of a novel high-conductance junction between the cascade subcells during the MOCVD growth of the structure reduces the complexity of processing to that required of a single-junction cell. Voltage addition has been demonstrated, with n of 10.0% (1-sun, AM2) in the AlGaAs (1.72 eV)/GaInAs (1.15 eV) system. The A1GaAs (1.72 eV)/GaAs lattice-matched pair allows demonstration of proof-of-concept structures; tunnel-junction-connected A1GaAs (1.72 eV)/ GaAs cascades show n as high as 13.9% at 1-sun, AM2, and three-terminal, two-junction A1GaAs (1.72 eV)/GaAs (1.42 eV) systems as high as 23.0% at 1-sun, AM2.

The Ingleside sand is a Pleistocene unit which crops out along the mainland margin of the Texas coast from Pass Cavallo to Baffin Bay. This sand body is a thin blanket of shoreface and eolian sediments, deposited as an extensive strandplain sand sheet, which extends into the subsurface under the Holocene barrier islands and lies directly on an oxidized surface of older Pleistocene deltaic sediments. The Ingleside strandplain sand was deposited during a mid-Wisconsin interstadial.

InGaAs concentrator cells with bandgaps of 1.15 and 1.35 eV have been developed. These cells are intended for eventual use in dual and triple-junction tandem solar cells, respectively. The InGaAs cell structures were grown by metal-organic chemical vapor deposition on GaAs substrates with grading layers to accommodate lattice mismatch. Efficiencies greater than 24% at 400 suns (AM1.5D, 100 mW/cm/sup 2/) have been demonstrated for InGaAs cells with either bandgap. Since the 1.15 eV InGaAs has a bandgap close to that of silicon, comparison of the photovoltaic effect in materials with direct and indirect bandgaps is possible. InGaAs demonstrates open-circuit voltage up to 800 mW (130 mW higher than Si) under concentration. Conversely, Si demonstrates a one-sun short-circuit current of 42 mA/cm/sup 2/ compared to 31 mA/cm/sup 2/ for InGaAs. Possible reasons for the higher voltages are given, and implications regarding projected tandem cell performance are discussed. >

Summary We describe a 77 year old man who developed pure red cell aplasia while receiving antituberculous therapy including isoniazid. Prompt recovery occurred following cessation of isoniazid. In this paper we also review previously described case reports of isoniazid-induced pure red cell aplasia.

The first observation of a high‐mobility, two‐dimensional electron gas in a modulation‐doped, strained GaAs–GaAs1−xPx (x=0.25) superlattice is reported. Electron sheet concentrations of n=6.4×1011 cm−2 and mobilities (4 K) of μ=1.2×104 cm2 V−1 S−1 are measured.