To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Thin film tin sulphide (SnS) was deposited on to molybdenum (Mo) substrates using metal organic chemical vapor deposition at 470°C using tetraethyltin and ditertiarybutylsulfide as precursors. In situ mass spectroscopy was used to study the exhaust gas species downstream of the reaction zone. The precursor vapor carrier gas was either nitrogen or hydrogen, thin film SnS only forming when the latter was used. Mass spectroscopy determined that hydrogen sulfide was being produced and playing a critical role in the vapor phase reaction process and adsorption of tin and sulfur on to the Mo surface. As-grown grain sizes were determined by scanning electron microscopy and were observed to be large averaging around 2 microns across. X-ray diffraction showed the films to be single phase SnS without any parasitic Sn2S3 or SnS2 phases, with a small amount of MoS2 also being detected.
New IUE observations confirm the differences between the Galactic and LMC ultraviolet extinction curves and show some evidence for variations within the LMC. Visual and infrared photometry and polarimetry show that the anomalous properties of the LMC dust do not extend to longer wavelengths. Despite the much different dust to gas ratios in the Galaxy and the Magellanic clouds, the dust formation efficiency is similar when the abundances are included.
Quantum information and computing are at the forefront of computer science, but their implementation relies on significant developments in materials science. In particular, suitable, lattice-matched substrates for two promising approaches—electrostatically defined quantum dots in Si/SiGe heterostructures, and superconducting circuits containing Josephson junctions—do not exist. Instead, these approaches rely on metamorphic substrates. In this article, we focus on the general structure and requirements of SiGe quantum dot heterostructures, the demands they impose on the underlying substrate, and the impact that properties of the metamorphic substrate have on device performance. Superconductor Josephson junction materials are briefly discussed in a similar fashion, and opportunities for future developments in both systems are described.
The coins here discussed are all surface finds from Tell Rifa‘at, one of the largest mounds in the ‘Azaz Casa, thirty-five kilometres north of Aleppo. They were collected together by the excavator of the site, Dr. M. V. Seton-Williams, during the course of three seasons' excavations at the site, 1956, 1960 and 1964. Although none of the coins is from stratified deposits, their range in time from the second century B.C. to the fourteenth century A.D. and their number afford an interesting sidelight on the later history of the site. They all fall within the range of the excavator's Level 1 : Roman to Hellenistic, first century A.D. to fourth century B.C., although the coin evidence now indicates occupation or interest in the area down to the fourteenth century A.D.
In a constant effort to capture effectively more of the spectral range from the sun, multi-junction cells are being investigated. In this context, the marriage of thin film and dye-sensitized solar cells (DSC) PV technologies may be able to offer greater efficiency whilst maintaining the benefits of each individual technology. DSC devices offer advantages in the nature of both the metal oxide photo-electrode and dye absorption bands, which can be tuned to vary the optical performance of this part of a tandem device, while CdTe cells absorb the majority of light above their band-gap in only a few microns of thickness. The key challenge is to assess the optical losses with the goal of reaching a net gain in photocurrent and consequently increased conversion efficiency. This study reports on the influence of optical losses from various parts of the stacked tandem structure using UV-VIS spectrometry and EQE measurements. A net gain in photocurrent was achieved from a model developed for the DSC/CdTe mechanically stacked tandem structure.
Clarification of the relationship between nitrogen profiles and wear behaviour has been sought by studying nitrogen implanted mild steel. Implant energy and dose were in the ranges 25 – 65 keV and 0.9 − 3 × 1017 1ions cm−2, respectively. Wear characteristics were measured with a ball-on-disc system followed by interferometric
analysis. Nitrogen distributions before and after wear were determined by Auger electron spectroscopy and Rutherford backscattering methods, and compared with wear track profiles. On balance, the data offers qualified support for nitrogen migration at low loads, although nitrogen was not detected for wear depths >2 times the implant depth. Observations of wear on the abrader ball-bearing surface and the role of oxygen in the wear process are reported.
Depth profiling of hydrogen in polymeric materials poses special problems. Backscattering methods are ruled out because of kinematics. Nuclear reaction methods are undesirable because small reaction cross sections necessitate large fluences of high mass projectiles and result in unacceptable levels of radiation damage. We have used a helium-induced proton-recoil technique with 3 MeV 4He particles to measure the hydrogen distribution in pristine and ion-implanted polyvinylidene fluoride (PVDF) films. The incident 4He particles stopped in the 25 micron PVDF films while the recoiling protons were detected after passing through the polymer film. Large changes in the hydrogen content of PVDF films implanted with modest fluences of 6 MeV carbon, oxygen and nickel ions were observed.
It was demonstrated, on general thermodynamic grounds, that, in non-hydrostatically stressed elastic systems, phase and grain interfaces undergo morphological destabilization due to different mechanisms of “mass rearrangement”. Destabilization of free surfaces due to the combined action of mass rearrangement in the presence of electrostatic field has been well known since the end of the 19th century. Currently, morphological instabilities of thin solid films with electro-mechanical interactions have found various applications in physics and engineering. In this paper, we investigate the combined effects of the stress driven rearrangement instabilities and the destabilization due to the electro-mechanical interactions. The paper presents relevant results of theoretical studies for ferroelectric thin films. Theoretical analysis involves highly nonlinear equations allowing analytical methods only for the initial stage of unstable growth. At present, we are unable to explore analytically the most important, deeply nonlinear regimes of growth. To avoid this difficulty, we developed numerical tools facilitating the process of solving and interpreting the results by means of visualization of developing morphologies.
• What is the role of the library in dealing with electronic information?
• What is the place of the library in the information transfer process?
• What links should a collection management area have with other areas of the library, and with the wider organization?
• What changes in the publishing industry are impacting on collections management?
Our world is being transformed by the increasing availability of electronic information. Whether one is seeking the complete works of William Shakespeare or the latest perinatal statistics, these are now available electronically – somewhere. As a result, libraries everywhere are shifting their focus from building up collections to providing access to information. Many colourful phrases have been devised to describe this shift: from the collection which includes a particular item ‘just in case’ it may be needed to the document delivery service which provides it ‘just in time’; or from the ‘warehouse’ to the ‘wherehouse’ approach.
The popular perception is that this growing availability of electronic information both renders traditional, primarily paper-based resources – and the libraries that house them – increasingly irrelevant, and that the new electronic information resources themselves offer simplicity and transparency in access and use. Both perceptions are wrong. Throughout history, there have been many examples of new communication technologies complementing rather than supplanting their predecessors. The invention of the printing press did not lead to the demise of the handwritten letter. When radio was first introduced it was expected that it would lead to the demise of the telephone: why talk to simply one other person, when you could talk to many at the same time? Ludicrous as this suggestion now seems, the point is that both radio and telephony best serve differing purposes. The same applies to electronic and paper-based media.
We are now living through a period of change when questions of which communication media are best suited for what purposes are still being assessed through a process of global trial and error. What is certain is that both paper and electronic forms will survive.