ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Discovery of a new population of high-energy γ-ray sources in the Milky Way (2000)

Macomb, D. J. ; Bertsch, D. L. ; Thompson, D. J. ; [et al.]

[s.l.] : Macmillian Magazines Ltd.

Nature 404 (2000), S. 363-365

add to mindlist on the mindlist

Details

ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] One of the great mysteries of the high-energy γ-ray sky is the group of ∼170 unidentified point sources found along the Galactic plane. They are more numerous than all other high-energy γ-ray sources combined and, despite 20 years of effort, no clear counterparts have been ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/35006001

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Giant photoresistivity and optically controlled switching in self-assembled nanowires (2001)

Kouklin, N. ; Menon, L. ; Wong, A. Z. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 79 (2001), S. 4423-4425

add to mindlist on the mindlist

Details

ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: We report the observation of giant photoresistivity in electrochemically self-assembled CdS and ZnSe nanowires electrodeposited in a porous alumina film. The resistance of these nanowires increases by one to two orders of magnitude when exposed to infrared radiation, possibly because of real-space transfer of electrons from the nanowires into the surrounding alumina by photon absorption. This phenomenon has potential applications in "normally on" infrared photodetectors and optically controlled switches. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1427156

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Enhanced band-gap blueshift due to group V intermixing in InGaAsP multiple quantum well laser structures induced by low temperature grown InP (2001)

Lee, A. S. W. ; MacKenzie, M. ; Thompson, D. A. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 78 (2001), S. 3199-3201

add to mindlist on the mindlist

Details

ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: Photoluminescence and cross-sectional transmission electron microscopy, combined with x-ray compositional analysis, have been used to study quantum well intermixing in an InGaAsP quantum well laser structure. Quantum well intermixing is induced by capping the samples with a layer of InP grown at low temperature (300 °C) and subjecting them to rapid thermal anneal treatments in the temperature range 600–800 °C. The presence of the low temperature InP layer, which contains an abundance of nonequilibrium point defects, significantly enhances the intermixing on annealing, producing a large band-gap blueshift. The microscopy results show good broadening with smeared interfaces, and the compositional analysis suggests this can be attributed to the intermixing of group V atoms. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1374231

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

Refractive indices of InGaAsP lattice-matched to GaAs at wavelengths relevant to device design (2000)

Wallace, S. G. ; Robinson, B. J. ; Mascher, P. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 76 (2000), S. 2791-2793

add to mindlist on the mindlist

Details

ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: The refractive indices of In1−xGaxAsyP1−y grown lattice-matched to GaAs by gas-source molecular-beam epitaxy, have been measured by variable angle spectroscopic ellipsometry. Indices in the transparent regime of these quaternaries, at 980 and 808 nm (relevant to the design of pump sources for erbium-doped fiber amplifiers and Nd:YAG lasers, respectively) and at 850 nm, are presented. © 2000 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.126477

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Characterization of defects in doped InGaAsN grown by molecular-beam epitaxy (2001)

Fleck, A. ; Robinson, B. J. ; Thompson, D. A.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 78 (2001), S. 1694-1696

add to mindlist on the mindlist

Details

ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: Defects in doped InGaAsN ((approximate)1.5% N) grown by gas source molecular-beam epitaxy are examined through Hall effect measurements. The behavior of the carrier concentration as a function of N content and doping concentration is examined. A Fermi statistics model based upon the experimental results has identified the energy levels and concentrations of three traps in as-grown InGaAsN. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1355011

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

Infrared response of multiple-component free-carrier plasma in heavily doped p-type GaAs (2001)

Zangooie, S. ; Schubert, M. ; Thompson, D. W. ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 78 (2001), S. 937-939

add to mindlist on the mindlist

Details

ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: Spectroscopic ellipsometry is used to measure the dielectric function of heavily doped p-type GaAs for wave numbers from 100 to 2000 cm−1. Due to partial filling of the heavy- and light-hole valence bands, heavy holes as well as light holes form a multiple-component plasma coupled with longitudinal optical phonons. Line-shape analysis of the infrared response allows differentiating between light- and heavy-hole contributions to the carrier plasma, and the results observed suggest nonparabolicity effects of the heavy- and light-hole valence bands in GaAs. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1343490

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Electronic Resource

Peroxidase isozyme patterns in the skin of maturing tomato fruit (2000)

Andrews, J. ; Malone, M. ; Thompson, D. S. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Plant, cell & environment 23 (2000), S. 0

add to mindlist on the mindlist

Details

ISSN: 1365-3040

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The cessation of tomato fruit growth is thought to be induced by an increase in the activity of enzymes which rigidify cell walls in the fruit skin. Peroxidase could catalyse such wall-stiffening reactions, and marked rises in peroxidase activity were recently reported in skin cell walls towards fruit maturity. Peroxidase isoforms in the fruit are here analysed using native gel electrophoresis. New isoforms of apparent Mr 44, 48 and 53 kDa are shown to appear in cell walls of the fruit skin at around the time of cessation of growth. It is inferred that these isozymes are present in the cell wall in vivo. Fruit from a range of non-ripening mutants were also examined. Some of these do not soften or ripen for many weeks after achieving their final size. The new isozymes were found in skin cell walls of mature fruit in each of these mutants, as in the wild-type and commercial varieties. It is concluded that the late-appearing isozymes are not associated with fruit ripening or softening, and are probably not ethylene-induced. They may act to control fruit growth by cross-linking wall polymers within the fruit skin, thus mechanically stiffening the walls and terminating growth.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00555.x

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

8

Electronic Resource

Thermal stability and mechanical performance of multiply heat-treated α-sialon ceramics densified with rare earth oxides (2000)

Liu, Q. ; Gao, L. ; Yan, D. S. ; [et al.]

Springer

Journal of materials science 35 (2000), S. 2229-2233

add to mindlist on the mindlist

Details

ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Typical α-sialon starting compositions, of formula Ln0.33Si9.3Al2.7O1.7N14.3, were densified by hot-pressing using Ln2O3 as sintering additives, where Ln = Nd, Dy, and Yb. The as-sintered materials were heat-treated at 1450°C for 96 hours and then re-sintered at 1800°C for 1 hour to observe the overlapping effects of both Ln2O3 and multiple heat-treatment on thermal stability of the Ln-α-sialon phase and also the change in microstructure. The kinds of grain boundary phases which occurred also affected the results. The hardness, fracture toughness and flexural strength of the materials were evaluated using indentation and three-point bending tests, respectively. Mechanical tests and detailed microstructural analysis have led to the conclusion that a multiple-mechanism is involved, with debonding, crack deflection, crack bridging, and elongated grain pull-out all making a significant contribution towards improving the fracture toughness. Nd-containing specimens were tough with a highest indentation fracture toughness K1C of 7.0 MPa m1/2. In contrast, Dy- and Yb-containing specimens were hard and brittle with a highest Vickers hardness HV10 of 18.0 GPa. All re-sintered specimens underwent β→α transformation to some degree, leading to a degradation of mechanical properties as a consequence.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004722825366

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

9

Electronic Resource

New heat treatment methods for glass removal from silicon nitride and sialon ceramics (2000)

Mandal, H. ; Thompson, D. P.

Springer

Journal of materials science 35 (2000), S. 6285-6292

add to mindlist on the mindlist

Details

ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Sialon ceramics were discovered simultaneously (but independently) in late 1971 at Newcastle University and also at the Toyota Research Laboratories in Japan. During the 30 years since their original discovery, the Newcastle laboratory has made a significant contribution to current understanding of the science and technology of these materials. Sialons are of interest as engineering materials for high temperature (〉1000°C) applications because they can be pressureless-sintered to high density and be designed to retain good mechanical properties even up to ≈1350°C, whereas competing metallic materials are weaker and prone to corrosion. A characteristic disadvantage of all nitrogen ceramics is that an oxide additive is always included in the starting mix to promote densification, and this remains in the final product as a glassy phase distributed throughout the grain boundaries of the final microstructure. Since the glass melts at ≈1000°C, the high temperature properties of the final ceramic are in fact determined by the properties of the grain-boundary glass. The most common method of improving high-temperature performance is to heat-treat the material at temperatures of 1100–1350°C in order to devitrify the glass into a mixture of crystalline phases. More specifically it is desirable to convert the glass into a sialon phase plus only one other crystalline phase, the latter having a high melting point and also displaying a high eutectic temperature (max ≈1400°C) in contact with the matrix sialon phase. Previous studies have shown that there are a limited number of possible metal-silicon-aluminium-oxygen-nitrogen compounds which satisfy these requirements. The present paper gives an overall review of this subject area and then summarises recent work at Newcastle aimed at total removal of residual grain boundary glass. This has been achieved by: (1) a post-preparative vacuum heat treatment process to remove the grain boundary glass from silicon nitride based ceramics in gaseous form, (2) above-eutectic heat-treatment (AET) of sialon-based ceramics to crystallize grain-boundary liquid into five-component crystalline sialon phases.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1026782723065

Permalink