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Alberto Pullia - One of the best experts on this subject based on the ideXlab platform.
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On the optimum area-balanced Filters for nuclear spectroscopy☆
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1996Co-Authors: Giancarlo Ripamonti, Alberto PulliaAbstract:Abstract The minimum noise Area-Balanced (A-B) Filters for nuclear spectroscopy are disentangled in the sum of two optimized Individual Filters. The former is the unipolar finite cusp Filter, used for pulse amplitude estimation but affected by baseline shift errors, the latter is a specific Filter used for baseline estimation. Each of them is optimized so as to give the minimum noise in the estimation of the pulse amplitude or of its baseline level. It is shown that double optimisation produces an overall optimum Filter exhibiting a total noise V n 2 equal to the sum of the noises V n1 2 and V n2 2 exhibited by each Filter Individually. This is a consequence of the orthogonality of the Individual Filter weight-functions in a function space where the norm is defined as V 2 n .
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On the optimum area-balanced Filters for nuclear spectroscopy☆
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1996Co-Authors: Giancarlo Ripamonti, Alberto PulliaAbstract:Abstract The minimum noise Area-Balanced (A-B) Filters for nuclear spectroscopy are disentangled in the sum of two optimized Individual Filters. The former is the unipolar finite cusp Filter, used for pulse amplitude estimation but affected by baseline shift errors, the latter is a specific Filter used for baseline estimation. Each of them is optimized so as to give the minimum noise in the estimation of the pulse amplitude or of its baseline level. It is shown that double optimisation produces an overall optimum Filter exhibiting a total noise V n 2 equal to the sum of the noises V n1 2 and V n2 2 exhibited by each Filter Individually. This is a consequence of the orthogonality of the Individual Filter weight-functions in a function space where the norm is defined as V 2 n .
Hugh Morrow - One of the best experts on this subject based on the ideXlab platform.
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Kirk-Othmer Encyclopedia of Chemical Technology - Cadmium and Cadmium Alloys
Kirk-Othmer Encyclopedia of Chemical Technology, 2010Co-Authors: Hugh MorrowAbstract:Cadmium, Cd, a Group 12 (IIB) element occurring between zinc and mercury, is a soft, ductile, silver-white metal having a distorted hexagonal close-packed structure. The crustal abundance of cadmium is somewhere between 0.1 and 0.5 ppm, and several cadmium minerals have been identified, the most common being greenockite, CdS. Cadmium is generally encountered in zinc ores, zinc-bearing lead ores, or complex copper-lead-zinc ores, where, however, it forms an isomorphic impurity in the zinc mineral sphalerite, ZnS. For this reason, cadmium is almost invariably recovered as a by-product from the processing of zinc, lead, and copper ores. Its oxidation state in almost all of its compoumds is + 2, although a few compounds have been reported in which cadmium exists in the + 1 oxidation state. There are eight natural isotopes. Cadmium forms a fume of brown-colored cadmium oxide, CdO, when heated in air. Other elements which react readily with cadmium metal upon heating include the halogens, phosphorus, selenium, sulfur, and tellurium. Cadmium is rapidly oxidized by hot dilute nitric acid. Cadmium occurs primarily as sulfide minerals in zinc, lead-zinc, and copper-lead-zinc ores. Beneficiation of these minerals, usually by flotation or heavy-media separation, yields concentrates which are then processed for the recovery of the contained metal values. Cadmium follows the zinc with which it is so closely associated. Air pollution problems and labor costs have led to the closing of older pyrometallurgical plants, and to increased electrolytic production. Cadmium production is dependent on the processing of zinc ores, which often contain 0.2 to 0.4% cadmium. Cadmium is classified as a toxic metal. Acute industrial poisoning by cadmium dust or fume can occur during the melting or pouring of cadmium metal; the welding, burning, or heating of cadmium-plated steel; or spraying, brazing, and overheating of cadmium metal. Protection should be provided by a properly designed exhaust ventilation system or by a suitable Individual Filter or air-supplied respirator. Industrial exposure to cadmium fumes and dust has been reported to result in emphysema, hypertension, kidney failure, osteomalacia, and perhaps an increased incidence of cancer. To help maintain the balance between supply and demand for cadmium, efforts can be made to recycle such cadmium-containing materials as spent nickel-cadmium batteries as well as dust and other residues from the pigment industry. Consumption of cadmium is in batteries, coating and plating, pigments, plastics and synthetic products, and alloys and other uses. Cadmium is an important component in brazing and low melting alloys, used in bearings, solders, and nuclear reactor control rods. Keywords: Occurrence; Cadmium; Sources; Recycling; Properties; Manufacture; Economics; Environmental Concerns; Specifications; Analytical Methods; Nealth & Safety; Uses; Minerals; Batteries; Nickel; Contamination; Pigments; Stabilizers; Coatings; Alloys; Cadmium Telluride; Cadmium Sulfide
D. S. Carr - One of the best experts on this subject based on the ideXlab platform.
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Kirk-Othmer Encyclopedia of Chemical Technology - Cadmium and Cadmium Alloys
Kirk-Othmer Encyclopedia of Chemical Technology, 2000Co-Authors: D. S. CarrAbstract:Cadmium, Cd, a Group 12 (IIB) element occurring between zinc and mercury, is a soft, ductile, silver-white metal having a distorted hexagonal close-packed structure. The crustal abundance of cadmium is somewhere between 0.1 and 0.5 ppm, and several cadmium minerals have been identified, the most common being greenockite, CdS. Cadmium is generally encountered in zinc ores, zinc-bearing lead ores, or complex copper–lead–zinc ores, where, however, it forms an isomorphic impurity in the zinc mineral sphalerite, ZnS. For this reason, cadmium is almost invariably recovered as a by-product from the processing of zinc, lead, and copper ores. Its oxidation state in almost all of its compounds is , although a few compounds have been reported in which cadmium exists in the oxidation state. There are eight natural isotopes. Cadmium forms a fume of brown-colored cadmium oxide, CdO, when heated in air. Other elements which react readily with cadmium metal upon heating include the halogens, phosphorus, selenium, sulfur, and tellurium. Cadmium is rapidly oxidized by hot dilute nitric acid. Cadmium occurs primarily as sulfide minerals in zinc, lead–zinc, and copper–lead–zinc ores. Beneficiation of these minerals, usually by flotation or heavy-media separation, yields concentrates which are then processed for the recovery of the contained metal values. Cadmium follows the zinc with which it is so closely associated. Air pollution problems and labor costs have led to the closing of older pyrometallurgical plants, and to increased electrolytic production. Cadmium production is dependent on the processing of zinc ores, which often contain 0.2 to 0.4% cadmium. Cadmium is classified as a toxic metal. Acute industrial poisoning by cadmium dust or fume can occur during the melting or pouring of cadmium metal; the welding, burning, or heating of cadmium-plated steel; or spraying, brazing, and overheating of cadmium metal. Protection should be provided by a properly designed exhaust ventilation system or by a suitable Individual Filter or air-supplied respirator. Industrial exposure to cadmium fumes and dust has been reported to result in emphysema, hypertension, kidney failure, osteomalacia, and perhaps an increased incidence of cancer. To help maintain the balance between supply and demand for cadmium, efforts can be made to recycle such cadmium-containing materials as spent nickel–cadmium batteries as well as dusts and other residues from the pigment industry. Consumption of cadmium is in batteries, coating and plating, pigments, plastics and synthetic products, and alloys and other uses. Cadmium is an important component in brazing and low melting alloys, used in bearings, solders, and nuclear reactor control rods.
H Geckeis - One of the best experts on this subject based on the ideXlab platform.
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multielement characterization of metal humic substances complexation by size exclusion chromatography asymmetrical flow field flow fractionation ultrafiltration and inductively coupled plasma mass spectrometry detection a comparative approach
Journal of Chromatography A, 2006Co-Authors: Eduardo Bolea, Maria P Gorriz, M Bouby, Francisco Laborda, J R Castillo, H GeckeisAbstract:Abstract The use of three different separation techniques, ultrafiltration (UF), high performance size exclusion chromatography (HPSEC) and asymmetrical flow field-flow fractionation (AsFlFFF), for the characterization of a compost leachate is described. The possible interaction of about 30 elements with different size fractions of humic substances (HS) has been investigated coupling these separation techniques with UV–vis absorption spectrophotometry and inductively coupled plasma-mass spectrometry (ICP-MS) as detection techniques. The organic matter is constituted by a polydisperse mixture of humic substances ranging from low molecular weights (around 1 kDa) to significantly larger entities. Elements can be classified into three main groups with regard to their interaction with HS. The first group is constituted by primarily the monovalent alkaline metal ions and anionic species like B, W, Mo, As existing as oxyanions all being not significantly associated to HS. The second group consists of elements that are at least partly associated to a smaller HS size fraction (such as Ni, Cu, Cr and Co). A third group of mainly tri- and tetravalent metal ions like Al, Fe, the lanthanides, Sn and Th are rather associated to larger-sized HS fractions. The three separation techniques provide a fairly consistent size classification for most of the metal ions, even though slight disagreements were observed. The number-average molecular weight ( M n ), the weight-average molecular weight ( M w ) and the polydispersity ( ρ ) parameters have been calculated both from AsFlFFF and HPSEC experiments and compared for HS and some metal-HS species. Differences in values can be partly explained by an overloading effect observed in the AsFlFFF experiments induced by electrostatic repulsion effects in the low ionic strength, high pH carrier solution. Size information obtained from ultrafiltration is not as resolved as for the other methods. Molecular weight cut-offs (MWCO) of the Individual Filter membranes refer to globular proteins and molecular weight information may therefore, deviate from that given by the other methods after calibration with polystyrene sulfonate (PSS) standards.
M Sorel - One of the best experts on this subject based on the ideXlab platform.
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multi wavelength Filters in silicon using superposition sidewall bragg grating devices
Optics Letters, 2014Co-Authors: Michael J Strain, S Thoms, D S Macintyre, M SorelAbstract:Multiple-Filter stopbands, with the potential to be nonuniformly spaced in frequency, are realized in a single integrated Bragg grating device on silicon. By utilizing a superposition of sidewall relief grating functions, N Individual Filter responses can be fabricated with a device length N× shorter than the equivalent serial set of gratings. Arbitrary combinations of eight-basis Filter responses were demonstrated as selected by an eight-bit pseudorandom number generator, showing the flexibility of the complex Bragg grating device design.