Download or read book The Conversion of Glycine 1 C14 to Protein C14 and C14O2 in Liver Slices from X irradiated Rats written by R. E. Kay and published by . This book was released on 1955 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biological Effects of Ionizing Radiation written by Marylou Ingram and published by . This book was released on 1966 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1955 with total page 1470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biological Effects of Ionizing Radiation Abstracts written by U.S. Atomic Energy Commission and published by . This book was released on 1966 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation Research written by Titus Evans and published by . This book was released on 1969 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Pentose Phosphate Pathway written by Terry Wood and published by Elsevier. This book was released on 2012-12-02 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pentose Phosphate Pathway aims to explore the pentose phosphate cycle and the practical techniques applied in its investigation. The main focus of the book is the pentose phosphate cycle in animals as well as microorganisms, and does not discuss the one related to photosynthesis. The book covers the formulation of the pathway, its types, and its alternative formulations; the preparation, processes, and analysis of the pathway; and the enzymes involved. Also covered in the book are the intermediates in intact cells and tissues; distribution of enzymes among different tissues and species; the operation, regulation, and overall control of the pathway; and the clinical, nutritional, and metabolic aspects of the pathway. The text is recommended for biologists and biochemists who would like to understand further the pentose phosphate pathway and the processes related to it.
Download or read book Compound 1080 written by United States. Environmental Protection Agency. Office of Pesticide Programs and published by . This book was released on 1985 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radioluminescence written by Jan Lindström and published by Linköping University Electronic Press. This book was released on 2021-03-24 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: A phosphor or scintillator is a material that will emit visible light when struck by ionising radiation. In the early days of diagnostic radiology, it was discovered that the radiation dose needed to get an image on a film, could be greatly reduced by inserting a fluorescent layer of a phosphor in direct contact with the film. Thus, introducing the step of converting the ionising radiation to light in a first step. Going forward in time, film has been replaced with photodetectors and there is now a variety of imaging x-ray systems, still based on phosphors and scintillators. There is continuous research going on to optimise between the radiation dose needed and a sufficient image quality. These factors tend to be in opposition to each other. It is a complicated task to optimise these imaging system and new phosphor materials emerges regularly. One of the key factors is the efficiency of the conversion from xrays to light. In this work this is denoted “extrinsic efficiency”. It is important since it largely determines the final dose to the patient needed for the imaging task. Most imaging x-ray detectors are based on phosphor or scintillator types where their imaging performance has been improved through tweaking of various parameters (light guide structure, higher density, light emission spectrum matching to photodetectors, delayed fluorescence quenching etc) One key factor that largely determines the extrinsic efficiency of a specific phosphor is the particle size. Larger particles result in a higher luminance of the phosphor for the same radiation dose as does as a thicker phosphor layer (to a limit). There exists already a battery of models describing various phosphor qualities. However, particle size and thickness have not been treated as a fully independent variables in previous model works. Indirectly, the influence of these parameters is accounted for, but the existing models were either considered too general, containing several complex parameters and factors to cover all kind of cases or too highly specialised to be easily applicable to fluorescent detectors in diagnostic radiology. The aim of this thesis is therefore to describe and assess a simple model denoted the “LAC-model” (after the original authors Lindström and Alm Carlsson), developed for a fluorescent layer using individual sub-layers defined by the particle size diameter. The model is thought to be a tool for quickly evaluating various particle size and fluorescent layer thickness combinations for a chosen phosphor and design. It may also serve as a more intuitive description of the underlying parameters influencing the final extrinsic efficiency. Further tests affirmed the validity of the model through measurements. The LACmodel produced results deviating a maximum of +5 % from luminescence measurements. During the development of the model various assumptions and simplifications were made. One assumption was the absence of a so called “dead layer”. This is a layer supposedly surrounding each particle decreasing the efficiency of converting x-rays to light. It is not completely “dead” as in inactive but is thought to have a reduced efficiency. This phenomenon was struggled with, when historically designing electron beam stimulated phosphors for various applications (i.e. displays, TV tubes etc). There are also articles reporting dead layer influence for x-ray detectors (usually spectrometers i.e. not for imaging). By introducing a dead layer in the LAC-model the effect of the layer was investigated and was found to result in a change of less than 8% for the extrinsic efficiency. It was also noted that sometimes a dead layer effect may emerge at surfaces of a scintillator slab but not necessarily connected to the phosphor particles themselves. Due to differences between phosphor material and the surroundings, an interface effect arose to compete with the process of inherent dead layers of the individual particles. It was found to be mostly negligible for x-rays in the studied energy and material range. However, an effect was shown for electrons as incident ionising radiation which could shed some light on the strangely neglected apparent dead layer created this way. Finally, applications, one involving developing a prototype for checking the light field radiation field coincidence, were evaluated for overall performance and the optimisation level of the applied fluorescent layer. Interesting findings were made during the development process: for the first time to the knowledge of the author, focus shift wandering was quantified in the corresponding movement of the x-ray field edge and a non-trivial discussion on the concept of an apparent light field edge resulted in a modified definition of the same. En fosfor eller scintillator är ett material som avger synligt ljus när det träffas av joniserande strålning. Inom diagnostisk radiologi upptäckte man i ett tidigt skede att stråldosen som behövdes för att få en bild på en röntgenfilm, reducerades kraftigt om man placerade ett fluorescerande skikt, en fosfor, i direkt kontakt med filmen. I nutid har film ersatts med fotodetektorer och det finns nu en mängd olika röntgenbildsystem men som fortfarande är baserade på fosforer och scintillatorer. Det pågår en kontinuerlig forskning för att optimera mellan erforderlig stråldos och en tillräcklig god diagnostisk bildkvalitet. Dessa faktorer tenderar att motverka varandra. Det är en komplicerad uppgift att optimera röntgenbildsystemen och nya fosformaterial dyker ständigt upp. En av de viktiga egenskaperna är fosforns omvandlingseffektivitet från röntgen till ljus. I detta arbete används benämningen ”extrinsisk (yttre) effektivitet". Denna egenskap är viktig eftersom den i stor utsträckning bestämmer den slutliga dosen till patienten som krävs för bilddiagnostiken. De flesta röntgendetektorer är baserade på fosfor- eller scintillatortyper där bildprestanda har förbättrats genom att utveckla olika parametrar (ljusledarstruktur, högre densitet, ljusemissionsspektrum som matchar fotodetektorer, minskad efterlysning etc.). En viktig faktor som i stor utsträckning bestämmer omvandlingseffektiviteten hos en specifik fosfor är partikelstorleken. Större partiklar resulterar i en högre luminescens (mer ljus) från fosforen för samma stråldos. Vilket också gäller för ett tjockare fosforlager (till en viss gräns!). Det finns redan fysikaliska modeller som beskriver olika fosforparametrar men partikelstorlek och fosfortjocklek har dock inte hanterats som fristående variabler i dessa modellarbeten. Istället har deras inverkan modellerats indirekt men det har gjort att de befintliga modellerna kan anses komplexa. De är antingen för generella som medför flera komplexa parametrar och faktorer för att täcka alla tänkbara varianter eller för specialiserade för att kunna tillämpas enkelt på fluorescerande detektorer i diagnostisk radiologi. Syftet med denna avhandling är därför att beskriva och analysera en praktisk modell betecknad ”LAC-modellen” (efter de ursprungliga författarna Lindström och Alm Carlsson). Den är utvecklad för ett fluorescerande block som består av flera underliggande skikt vars tjocklek bestäms av partiklarnas diameter. Avsikten med modellen är att den ska vara ett verktyg för att snabbt utvärdera olika varianter av partikelstorlek och tjockleks-kombinationer för en vald fosfor med i grunden samma design. Experiment har bekräftat modellens giltighet och mätresultat visar att modellresultaten avvek maximalt +5% från luminiscensmätningar. Utvecklingen av modellen krävde olika antaganden och förenklingar. Ett antagande var frånvaron av ett så kallat ”dött lager”. Det är ett skikt som antas omge varje partikel och som därför minskar omvandlingseffektiviteten från röntgen till ljus. Det är dock inte helt "dött" i meningen helt inaktivt men har en mindre förmåga att omvandla röntgen till ljus jämfört med fosforns huvudmaterial. Historisk sett har man försökt åtgärda detta fenomen under lång tid och speciellt för applikationer där man använt sig av elektronstrålar (dvs olika typer av displayer, TV-rör etc.). Just för elektroner har man sett att döda skiktet tenderar att växa med tiden. Det finns också artiklar som rapporterar en påverkan av röntgendetektorers funktion (vanligtvis dock för spektrometrar, dvs inte för avbildning). Genom att införa ett dött skikt i LAC-modellen undersöktes skiktets effekt och visade sig resultera i en förändring på mindre än 8% för effektiviteten. Det noterades också att ibland kan en dödskiktsliknande effekt uppstå vid ytor av ett scintillatorblock men inte nödvändigtvis pga. av själva fosforpartiklarnas ljusomvandlingsegenskaper. Då det uppstår skillnader mellan fosformaterialet och omgivningen får man en s.k. gränsskiktseffekt som s.a.s. konkurrerar med kemiskt döda skiktet på de enskilda partiklarna. De döda skiktens inverkan visade sig i princip försumbara för röntgenbild-detektorer - åtminstone inom det studerade energi- och materialområdet. En tydlig effekt kunde dock noteras för joniserande strålning i form av elektroner. Simuleringarna kunde ge en bättre bild av egenskaperna hos det döda skiktet som skapats på detta sätt. Slutligen utvärderades två applikationer med hjälp av LAC-modellen: en prototyp för kontroll av ljusfältets och strålfältets överenstämmelse i läge och position. Samt en etablerad produkt med samma användningsområde. I båda fallen undersöktes det fluorescerande skiktets optimeringsgrad. Intressanta resultat noterades under utvecklingsprocessen av prototypen: för första gången, så vitt författaren vet, kunde man kvantifiera röntgenrörs s.k. fokusvandring.
Download or read book Life Atomic written by Angela N. H. Creager and published by University of Chicago Press. This book was released on 2013-10-02 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: After World War II, the US Atomic Energy Commission (AEC) began mass-producing radioisotopes, sending out nearly 64,000 shipments of radioactive materials to scientists and physicians by 1955. Even as the atomic bomb became the focus of Cold War anxiety, radioisotopes represented the government’s efforts to harness the power of the atom for peace—advancing medicine, domestic energy, and foreign relations. In Life Atomic, Angela N. H. Creager tells the story of how these radioisotopes, which were simultaneously scientific tools and political icons, transformed biomedicine and ecology. Government-produced radioisotopes provided physicians with new tools for diagnosis and therapy, specifically cancer therapy, and enabled biologists to trace molecular transformations. Yet the government’s attempt to present radioisotopes as marvelous dividends of the atomic age was undercut in the 1950s by the fallout debates, as scientists and citizens recognized the hazards of low-level radiation. Creager reveals that growing consciousness of the danger of radioactivity did not reduce the demand for radioisotopes at hospitals and laboratories, but it did change their popular representation from a therapeutic agent to an environmental poison. She then demonstrates how, by the late twentieth century, public fear of radioactivity overshadowed any appreciation of the positive consequences of the AEC’s provision of radioisotopes for research and medicine.
Download or read book A Review of Sodium Monofluoroacetate compound 1080 written by Stephen P. Atzert and published by . This book was released on 1972 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the Second World War sodium monofluoroacetate, or sodium fluoroacetate (Compound 1080), has been the subject of wide research in the United States and elsewhere. Based on this research, it has been approved for animal damage control work by several nations. In the United States sodium monofluoroacetate has been a tool used by the Bureau of Sport Fisheries and Wildlife to control coyote and rodent damage, as well as a tool used by private pest control operators to control commensal rodents. Despite 25 years of worldwide research and practical experience, the use of Compound 1080 is still embroiled in controversy. The purpose of this monograph is to summarize current information on sodium monofluoroacetate, to review use patterns, and to provide a base for further studies.
Download or read book Reference Information on the Toxicity of Sodium Monofluoroacetate compound 1080 written by J. R. Backholer and published by . This book was released on 1980 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bioregulators for Pest Control written by Paul Arthur Hedin and published by . This book was released on 1985 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Physiological basis of phloem transport of agrichemicals; Interference by herbicides with photosynthetic electron transfer. New appoaches to chemical control of plant pathogens. Elicitation of diases resistence in plants by the expression of latent genetic information. Use of subtoxic herbicide pretreatments to improve crop tolerance to herbicides. Regulation of plant growth and development by endogenous hormones. Plant bioregulators: overiew, use and development. Effects of allelopathic chemicals on crop productivity. Use of transition-State theory in the development of bioactive molecules. Role of mixed-function oxidades in insect growth and development. Inhibition of reproduction in insect control. Potent antifeedants from the African medicinal plant Bersama abyssinica. Cockroach control with juvenoids. Some chemical ecological approaches to the control of stored-product insects and mites. Phytochemical disruption of inset development and behavior. Proallatocidins. Propiomate and methyl malomate metabolisn in insects. Suicidal destruction of cytochrome P-450 in the desing of inhibitors of insect juvenile hormone biosynthesis. Detoxification enzyme relationships in arthropods of differing feeding strategies. Endotoxin of Bacillus thuringiensis isaelensis: broad-spectum toxixity and neural response elicited in mice and insects. Bioassay of anti juvenile hormone compounds: an alternative approach. Applications of immunoassay to paraquat and other pestides. Role of natural product chemistry. Do plants psychomanipulate insects. Protein hydrolysate volatiles as insect attractants. Beetles: pheromonal chemists par excellence. Sexual messages of moths: chemical themes are known and new research challenges arise. Alkaloidal ant venoms: chemistry and biological activities. Use of natural products and their analogues for combating pests of agricultural and public health importance in Africa. Insect antifeedant terpnoids wild sumflower: a possible of resistance to the sunflower moth. Insect feeding deterrents from semiarid and arid land plants. Secondary metabolites from plants ans their alleolochemic effects. Insect antifeedants metabolites from plants their allelochemic affects. Insect antifeedants from the peruvian plant Alchornea triplinrvi a Why are green cterpillars green.
Download or read book Textbook of Nuclear Medicine written by Michael Andrew Wilson and published by Raven Press. This book was released on 1998 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topics incl. pediatrics bone densitometry nonthyroid endocrine fundamentals of nuclear medicine protocols etc.
Download or read book The New Zealand Journal of Agriculture written by and published by . This book was released on 1919 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Improving Conventional Control of Possums written by and published by . This book was released on 1996 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
