Recent Developments in the Determination of Positron Annihilation Rate Distributions by Regularized Solution of Integral Equations

1992 ◽  
Vol 105-110 ◽  
pp. 1871-1874 ◽  
Author(s):  
R.B. Gregory
2008 ◽  
Vol 14 (2) ◽  
pp. 126-128
Author(s):  
Tran Dai Nghiep

Measurement system for determination of positron annihilation rate is consisted of HPGe detector, multichannel analyser and Na$^{22}$ positron source. The result of annihilation rate measurement in wetted filter paper is treated. The formula of energy transfer model is used for explanation obtained data quantitatively.


Author(s):  
William Krakow ◽  
David A. Smith

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.


Author(s):  
Hernâni Marques ◽  
Pedro Cruz-Vicente ◽  
Tiago Rosado ◽  
Mário Barroso ◽  
Luís A. Passarinha ◽  
...  

Environmental tobacco smoke exposure (ETS) and smoking have been described as the most prevalent factors in the development of certain diseases worldwide. According to the World Health Organization, more than 8 million people die every year due to exposure to tobacco, around 7 million due to direct ETS and the remaining due to exposure to second-hand smoke. Both active and second-hand exposure can be measured and controlled using specific biomarkers of tobacco and its derivatives, allowing the development of more efficient public health policies. Exposure to these compounds can be measured using different methods (involving for instance liquid- or gas-chromatographic procedures) in a wide range of biological specimens to estimate the type and degree of tobacco exposure. In recent years, a lot of research has been carried out using different extraction methods and different analytical equipment; this way, liquid–liquid extraction, solid-phase extraction or even miniaturized procedures have been used, followed by chromatographic analysis coupled mainly to mass spectrometric detection. Through this type of methodologies, second-hand smokers can be distinguished from active smokers, and this is also valid for e-cigarettes and vapers, among others, using their specific biomarkers. This review will focus on recent developments in the determination of tobacco smoke biomarkers, including nicotine and other tobacco alkaloids, specific nitrosamines, polycyclic aromatic hydrocarbons, etc. The methods for their detection will be discussed in detail, as well as the potential use of threshold values to distinguish between types of exposure.


Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 189
Author(s):  
Susana Campuzano ◽  
Paloma Yáñez-Sedeño ◽  
José Manuel Pingarrón

The multifaceted key roles of cytokines in immunity and inflammatory processes have led to a high clinical interest for the determination of these biomolecules to be used as a tool in the diagnosis, prognosis, monitoring and treatment of several diseases of great current relevance (autoimmune, neurodegenerative, cardiac, viral and cancer diseases, hypercholesterolemia and diabetes). Therefore, the rapid and accurate determination of cytokine biomarkers in body fluids, cells and tissues has attracted considerable attention. However, many currently available techniques used for this purpose, although sensitive and selective, require expensive equipment and advanced human skills and do not meet the demands of today’s clinic in terms of test time, simplicity and point-of-care applicability. In the course of ongoing pursuit of new analytical methodologies, electrochemical biosensing is steadily gaining ground as a strategy suitable to develop simple, low-cost methods, with the ability for multiplexed and multiomics determinations in a short time and requiring a small amount of sample. This review article puts forward electrochemical biosensing methods reported in the last five years for the determination of cytokines, summarizes recent developments and trends through a comprehensive discussion of selected strategies, and highlights the challenges to solve in this field. Considering the key role demonstrated in the last years by different materials (with nano or micrometric size and with or without magnetic properties), in the design of analytical performance-enhanced electrochemical biosensing strategies, special attention is paid to the methods exploiting these approaches.


2017 ◽  
Vol 10 (1) ◽  
pp. 5-29 ◽  
Author(s):  
F. Berthiller ◽  
C. Brera ◽  
M.H. Iha ◽  
R. Krska ◽  
V.M.T. Lattanzio ◽  
...  

This review summarises developments in the determination of mycotoxins over a period between mid-2015 and mid-2016. Analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone are covered in individual sections. Advances in proper sampling strategies are discussed in a dedicated section, as are methods used to analyse botanicals and spices and newly developed liquid chromatography mass spectrometry based multi-mycotoxin methods. This critical review aims to briefly discuss the most important recent developments and trends in mycotoxin determination as well as to address limitations of presented methodologies.


2004 ◽  
Vol 58 (7-8) ◽  
pp. 338-342
Author(s):  
Dragana Cickaric ◽  
Ljubinka Rajakovic

The quality of life depends on water quality. Good water quality and the rational use of water are an absolute need of the new millennium. Although it is an ecological and health priority to prohibit the contamination of water and water protection, it is a responsibility for environmental engineers and chemists to develop and apply effective methods for monitoring and controlling of water quality, and at that way prevent ecological and technological catastrophe on time. In this paper modern methods and process for monitoring, control and detection of cyanide in water and wastewater are presented. Recent developments in instrumental techniques and treatment for determination of this toxic substance in water are described, particularly the methods according to green analytical aspects.


1975 ◽  
Vol 62 (5) ◽  
pp. 1777-1789 ◽  
Author(s):  
J. D. McNutt ◽  
V. B. Summerour ◽  
A. D. Ray ◽  
P. H. Huang ◽  
D. A. Johnson

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