Evaluation of commercial pyroelectric detectors

A series of commercially available pyroelectric detectors made from PVF2, LTO, SBN, and TGS were evaluated in terms of responsivity and detectivity as a function of frequency. The performance of the detectors evaluated was very different, depending upon the manufacturer of the detector, and this dependency was primarily related to the thickness of the various detectors. The best detectors of each material were comparable in performance at frequencies around 10 Hz but differed radically at frequencies above 100 Hz

Development of a long life thermal cell Final report

Development of long life thermal cells, environmental and electrochemical performance tests to evaluate their capability and reproductibilit

Reusable thermal cycling clamp

A reusable metal clamp for retaining a fused quartz ampoule during temperature cycling in the range of 20 deg C to 1000 deg C is described. A compressible graphite foil having a high radial coefficient of thermal expansion is interposed between the fused quartz ampoule and metal clamp to maintain a snug fit between these components at all temperature levels in the cycle

Vapor phase growth of group 3, 4, and 5 compounds by HCl transport of elements

Technique has been devised for vapor-phase epitaxial growth of group 3, 4, and 5 binary, ternary, or quaternary compounds by HCl transport of the constituent elements or dopants. Technique uses all the constituents of the alloy system in their elemental form. Transport of these elements by an HCl + H2 carrier gas facilitates their transport as subchlorides

A study of beryllium and beryllium-lithium complexes in single crystal silicon

When beryllium is thermally diffused into silicon, it gives rise to acceptor levels 191 MeV and 145 meV above the valence band. Quenching and annealing studies indicate that the 145-MeV level is due to a more complex beryllium configuration than the 191-MeV level. When lithium is thermally diffused into a beryllium-doped silicon sample, it produces two acceptor levels at 106 MeV and 81 MeV. Quenching and annealing studies indicate that these levels are due to lithium forming a complex with the defects responsible for the 191-MeV and 145-MeV beryllium levels, respectively. Electrical measurements imply that the lithium impurity ions are physically close to the beryllium impurity atoms. The ground state of the 106-MeV beryllium level is split into two levels, presumably by internal strains. Tentative models are proposed

Temperature profiles in high gradient furnaces

Accurate temperature measurement of the furnace environment is very important in both the science and technology of crystal growth as well as many other materials processing operations. A high degree of both accuracy and precision is acutely needed in the directional solidification of compound semiconductors in which the temperature profiles control the freezing isotherm which, in turn, affects the composition of the growth with a concomitant feedback perturbation on the temperature profile. Directional solidification requires a furnace configuration that will transport heat through the sample being grown. A common growth procedure is the Bridgman Stockbarger technique which basically consists of a hot zone and a cold zone separated by an insulator. In a normal growth procedure the material, contained in an ampoule, is melted in the hot zone and is then moved relative to the furnace toward the cold zone and solidification occurs in the insulated region. Since the primary path of heat between the hot and cold zones is through the sample, both axial and radial temperature gradients exist in the region of the growth interface. There is a need to know the temperature profile of the growth furnace with the crystal that is to be grown as the thermal load. However it is usually not feasible to insert thermocouples inside an ampoule and thermocouples attached to the outside wall of the ampoule have both a thermal and a mechanical contact problem as well as a view angle problem. The objective is to present a technique of calibrating a furnace with a thermal load that closely matches the sample to be grown and to describe procedures that circumvent both the thermal and mechanical contact problems

Cloning of the rDNA repeat unit: An EcoRI fragment spanning the entire nontranscribed spacer region of Neurospora crassa wild type strain 74A

Cloning of the rDNA repeat unit: An EcoRI fragment spanning the entire nontranscribed spacer region of Neurospora crassa wild type strain 74

Development of a long life thermal cell Status report no. 1

Quality control program and cell construction flow chart for development of 50 ampere hour thermal cell with copper oxide cathod

Implementation, impact and costs of policies for safe staffing in acute NHS trusts

The aim of this research has been to describe the implementation of safe staffing policies in NHS general acute Trusts in England looking at costs and consequences, and examining the factors that have influenced implementation. A mix of qualitative and quantitative methods were used (national survey, analysis of national data, four case studies, realist evaluation) to examine the impact of policies nationally, and explore commonality and variation in local responses to safe staffing policies. The report is based on independent research commissioned and funded by the NIHR Policy Research Programme (“Implementation, Impact and Costs of Policies for Safe Staffing in Acute NHS Trusts”, PR-ST-1115-10017). The views expressed are those of the authors and not necessarily those of the NIHR, the Department of Health and Social Care, ‘arm’s length bodies’ or other government departments

Acrolein Dimer as a Marker for Direct Detection of Acrolein in Wine

Acrolein is highly toxic and its presence in wine has been correlated with the development of bitterness.Analytical detection and quantification in aqueous solutions are challenging due to high reactivityand problems with chemical derivative analysis. Here we demonstrate the potential of a naturalderivative, formed under conditions prevailing in wine, as a marker for acrolein detection. Solid-phasemicroextraction (SPME) coupled with gas chromatograph mass spectrometry (GC-MS) was validated asa technique for direct detection of the acrolein dimer. Conventional GC-MS analysis using a quadrupolemass spectrometer did not provide sufficient chromatographic resolution for the separation of the targetanalyte from interfering compounds. Accurate mass measurements with time-of-flight (TOF)-MS, on theother hand, allowed qualitative and quantitative measurements of the acrolein dimer. This work lays theanalytical foundation for studies on the evolution of acrolein and its dimer in solution