Planar-junction, top-illuminated GaInAs/InP pin photodiode with bandwidth of 25 GHz

A top-illuminated GaInAs/InP pin photodiode has been produced in a planar-junction configuration, which combines high reliability (no change in dark current over 4700 h at 175 degrees C) with the widest bandwidth (25 GHz), and highest quantum efficiency (80% at 1.55 mu m), yet reported for this type of device.<>     

Measurement of cable switching transients in undergrounddistribution systems

Routine operation of loadbreak elbows and disconnects to switch underground distribution power cables results in transient overvoltages. Presented are the results and analyses of field tests performed in two 24.94 kV systems where transient voltages were recorded during switching operations. Traveling wave propagation characteristics in the power cables, the influence of underground distribution system topology, and switching device arc behaviour are discussed. Conclusions are reached regarding the severity of the switching overvoltages     

Reviews

A VISUAL APPROACH TO PARK DESIGN by A. J. Rutledge, John Wiley, 1985. 180pp.

FIFTY YEARS OF LANDSCAPE DESIGN: 1934-84 Edited by Sheila Harvey and Stephen Rettig, Landscape Press, 1985.

DES PAYSAGES, POUR QUI? POURQUOI? COMMENT? by Georges Neuray, Les Presses Agronomiques de Gembloux, Belgium, 1982, 589 pp. 1640 Belgian Francs.

THE PAST IS A FOREIGN COUNTRY by Professor David Lowenthal, Cambridge University Press, 1985, 490 pp, £27.50 (H/B), £9.95 (P/B).

INTERPRETING THE LANDSCAPE: LANDSCAPE ARCHAEOLOGY IN LOCAL STUDIES by Michael Aston. B. T. Batsford, London 1985. Price £9.95 (P/B).

AGRICULTURAL LANDSCAPES: A SECOND LOOK, by R. Westmacott and T. Worthington, Countryside Commission (CCP 168, 1984) £7.00

AGRICULTURAL LANDSCAPES: AN APPROACH TO THE IMPROVEMENT, by P. Hamilton and J. Woolcock, Countryside Commission (CCP 169, 1984) £8.00

AGRICULTURAL LANDSCAPES: DEMONSTRATION FARMS, by R. Cobham et al, Countryside Commission (CCP 170, 1984) £13.00

REVIEWS OF UNITED KINGDOM STATISTICAL SOURCES, VOLUME XVII, Weather by B. W. Atkinson and Water by E. C. Penning-Rowsell and D. J. Porter. Published for the Royal Statistical Society and Economic and Social Research Council by Pergamon Press, 1985, 266 pp.

THE COUNTRYSIDE HANDBOOK by Alan Rogers, John Blunden and Nigel Curry, Open University/Croom Helm, 1985, 98 pp, £5.95.

THE CHANGING COUNTRYSIDE — edited by John Blunden and Nigel Curry. Open University/Croom Helm, 1985, 270 pp, £11.95.     

High gain laser performance in alexandrite

Half-jouleQ-switched pulses of 20 ns duration have been obtained from an alexandrite laser operating on the high-gainR-line. Unique tandem pulsing, involving both a fixed and a tunable frequency pulse, is also observed.     

A putative glucan synthase gene dps detected in exopolysaccharide-producing Pediococcus damnosus and Oenococcus oeni strains isolated from wine and cider

Some lactic acid bacteria can induce viscosity in wine, beer and cider by production of exopolysaccharides (EPS). A polymerase chain reaction (PCR) assay was previously described for the detection of ropy Pediococcus damnosus strains in wine [J. Appl. Microbiol. 90 (2001) 535]. The primers used in that study, PF5 and PF6, are investigated in addition to new primers which broaden the range of spoiling agents detectable by PCR. Primers PF1 and PF8 allow the amplification of DNA from ropy P. damnosus strains isolated from wine, as was observed with PF5 and PF6. In addition, PF1 and PF8, unlike PF5 and PF6, are able to generate an amplicon using template DNA from a ropy P. damnosus strain isolated from cider and a ropy Oenococcus oeni strain isolated from champagne. Two different ropy Lactobacillus species were also isolated, but their DNA was not amplified using primers PF1 and PF8. The new primers PF1 and PF8 were chosen from the sequence of gene dps, a putative glucan synthase gene, found across all the ropy P. damnosus strains isolated, from both wine or cider, and also in a ropy O. oeni strain. To our knowledge, this is the first time that an EPS-producing O. oeni strain is described. Glucan biosynthesis was assessed by agglutination tests done with Streptococcus pneumoniae type 37-specific antibodies, which specifically detect glucan-producing cells. The results show that there is a direct correlation between glucan production and detection of gene dps. Therefore, Dps is considered a candidate for the glucan synthase enzyme responsible for EPS production by ropy strains of P. damnosus and O. oeni.     

Ion-chromatographic characterization of ethoxylated anionic surfactants

Alkyl ether sulfates (AES), analyzed by nonsuppressed or single-column ion chromatography with conductivity detection, generate profiles that are characteristic of the ethoxylate content. Identification of ethoxylation content was accomplished by calculating the slope of the log of the peak area for each homologue vs. the number of ethoxyl groups in the homologue. Quantitation of ethylene oxide content as well as quantitation of mixed alkyl sufates in the presence of AES in mixed surfactant systems is possible. Raw materials require only dilution in mobile phase, while finished products must be subjected to a solid-phase extraction by means of a reverse-phase cartridge and an ion-pair reagent. The chromatogram of the anionic surfactant yields the moles of ethoxylation and the characterization of the ethoxyl chain distribution. Anionic surfactant mixtures in products are identified and quantitated by reference to AES raw materials with a similar slope.     

Highly reliable planar GaInAs/InP photodiodes with high yield madeby atmospheric pressure MOVPE

A process for making GaInAs/InP PIN photodiodes based on atmospheric pressure MOVPE is described. The technique gives devices with very low dark currents (≪1 nA) and capacitances (<0.2 pF). Yields on large area wafers greater than 80% can be achieved and extremely good reliability has been demonstrated (<0.4 FIT at 20°C)