Effect of Liquid Salt Bath Nitrocarburizing on Mechanical Properties of Low-Alloy Sintered Steels

The purpose of this study is to produce Fe–2Cu–2Ni–0.7Mo–XC steels by means of the powder metallurgy at different sintering temperatures. The mechanical properties of sintered steels have recently reached a level equivalent to that of steels produced by other processes. The static and dynamic mechanical properties of parts made of sintered steel depend on density and microstructure. Many process parameters such as initial composition, alloying elements, atmosphere, time, sintering temperature, and nitrocarburizing influence the microstructure of steel parts. The compacts’ preparation involves powder mixing, cold pressing at 500 MPa, and sintering at 1250°C within the H2 atmosphere for 2 hours and 25 min. The influence of sintering temperature on both hardness and microstructure of the steel is investigated. In this study, sintered Fe–2Cu–2Ni–0.7Mo–XC-type steels are developed. The impact of nitrocarburizing on this structure is evaluated. Microscopy, SEM, and destructive testing are used for characterization of the sintered steels.Метою даної роботи є одержання сталей типу Fe–2Cu–2Ni–0,7Mo–XC методами порошкової металурґії за різних температур спікання. Механічні властивості спечених сталей нещодавно сягнули рівня, аналогічного рівню сталей, що виробляються іншими методами. Статичні та динамічні механічні властивості деталів із спеченої сталі визначаються густиною та мікроструктурою. При цьому велика кількість характеристик процесу, наприклад, вихідний склад, леґувальні елементи, атмосфера, час, температура спікання та нітроцементація впливають на мікроструктуру сталевих деталів. Виготовлення пресованого матеріялу потребує змішування порошку, холодного пресування при 500 МПа та спікання при температурі у 1250°C в атмосфері Н22 протягом 2 годин 25 хв. Було досліджено вплив температури спікання на твердість і мікроструктуру сталі. В даній роботі було розглянуто сталі типу Fe–2Cu–2Ni–0,7Mo–XC. Було проведено оцінку впливу нітроцементації на такі структури. Для характеризації спечених сталей використовувалися мікроскопія, СЕМ та випробування на руйнування.Целью данной работы является получение сталей типа Fe–2Cu–2Ni–0,7Mo–XC методами порошковой металлургии при различных температурах спекания. Механические свойства спечённых сталей недавно достигли уровня, аналогичного уровню сталей, производимых другими методами. Статические и динамические механические свойства деталей из спечённой стали определяются плотностью и микроструктурой. При этом большое количество характеристик процесса, например, исходный состав, легирующие элементы, атмосфера, время, температура спекания и нитроцементация, влияют на микроструктуру стальных деталей. Изготовление прессованного материала требует смешивания порошка, холодного прессования при 500 МПа и спекания при температуре 1250°C в атмосфере Н22 в течение 2 часов 25 мин. Было исследовано влияние температуры спекания на твёрдость и микроструктуру стали. В данной работе были рассмотрены стали типа Fe–2Cu–2Ni–0,7Mo–XC. Была проведена оценка влияния нитроцементации на такие структуры. Для характеризации спечённых сталей использовались микроскопия, СЭМ и испытания на разрушение

Proton spectroscopic imaging of brain metabolites in basal ganglia of healthy older adults

Object: We sought to measure brain metabolite levels in healthy older people. Materials and methods: Spectroscopic imaging at the level of the basal ganglia was applied in 40 participants aged 73–74 years. Levels of the metabolites N-acetyl aspartate (NAA), choline, and creatine were determined in "institutional units" (IU) corrected for T1 and T2 relaxation effects. Structural imaging enabled determination of grey matter (GM), white matter (WM), and cerebrospinal fluid content. ANOVA analysis was carried out for voxels satisfying quality criteria. Results: Creatine levels were greater in GM than WM (57 vs. 44 IU, p < 0.001), whereas choline and NAA levels were greater in WM than GM [13 vs. 10 IU (p < 0.001) and 76 versus 70 IU (p = 0.03), respectively]. The ratio of NAA/cre was greater in WM than GM (2.1 vs. 1.4, p = 0.001) as was that of cho/cre (0.32 vs. 0.16, p < 0.001). A low voxel yield was due to brain atrophy and the difficulties of shimming over an extended region of brain. Conclusion: This study addresses the current lack of information on brain metabolite levels in older adults. The normal features of ageing result in a substantial loss of reliable voxels and should be taken into account when planning studies. Improvements in shimming are also required before the methods can be applied more widely

Variance components associated with long-echo-time MR spectroscopic imaging in human brain at 1.5T and 3T

<div><p>Object</p><p>Magnetic resonance spectroscopic imaging (MRSI) is increasingly used in medicine and clinical research. Previous reliability studies have used small samples and focussed on limited aspects of variability; information regarding 1.5T versus 3T performance is lacking. The aim of the present work was to measure the inter-session, intra-session, inter-subject, within-brain and residual variance components using both 1.5T and 3T MR scanners.</p><p>Materials and methods</p><p>Eleven healthy volunteers were invited for MRSI scanning on three occasions at both 1.5T and 3T, with four scans acquired at each visit. We measured variance components, correcting for grey matter and white matter content of voxels, of metabolite peak areas and peak area ratios.</p><p>Results</p><p>Residual variance was in general the largest component at 1.5T (8.6–24.6%), while within-brain variation was the largest component at 3T (12.0–24.7%). Inter-subject variation was around 5%, while inter- and intra-session variance were both generally small.</p><p>Conclusion</p><p>Multiple variance contributions associated with MRSI measurements were quantified and the performance of 1.5T and 3T MRI scanners compared using data from the same group of subjects. Residual error is much lower at 3T, but other variance components remain important.</p></div

Ionometric and fricke electron and gamma dosimetry for the implementation of waste water treatment by radiation in Portugal

Application of radiation as an efficient process to reduce the microbial levels in materials (food, environmental, health care products). Irradiation of organic and inorganic compounds with electron and gamma rays can modify the micro organisms, depending on the energy, dose rate, and others variables related to the irradiation conditions. Anthropogenic sources have been responsible for introducing high levels of chemical elements and compounds into the environment, many of this through the industrial waste waters. This is an issue of global concern, with potential impact on human health and the environment. IAEA recognizes the potentiality of radiation technology to clean up waste discharges, and since 2003 IAEA participate in this project. Although this is a multidisciplinary project, by the physical point of view the main objective is to characterize the most efficient electron (by intercomparison with gamma) beam, obtaining the better irradiation geometry, to implement waste water (originated in hospitals, food industry ...) treatments. Until now, we've characterized electron beams with Ionometric and fricke dosimetry at non-standard irradiation conditions, in commercial Linacs for radiotherapy purposes. We used a Varian Clinac 2100 CD, with the special TBI ETRAY conditions and nominal dose rate of 1000 UM/min, and an Elekta Digital Precise with nominal dose rate of 400 UM/min. The better dose rates obtained in water were approximately equal to 1.4 kGy/h and 0.7 kGy/h, respectively. The impact of the radiation has been studied microbiologically, toxicologically and chemically, and the evaluation between this kind of radiation and cobalt gamma radiation is also carried out at the same time. The results obtained until know and the continuous support of the IAEA experts in the project, indicates that this project will contribute to a better quality of the Portuguese industrial or hospital complexes, minimising the impact of pollutants on the environment.info:eu-repo/semantics/publishedVersio

Ionometric and fricke electron and gamma dosimetry for the implementation of waste water treatment by radiation in Portugal

Application of radiation as an efficient process to reduce the microbial levels in materials (food, environmental, health care products). Irradiation of organic and inorganic compounds with electron and gamma rays can modify the micro organisms, depending on the energy, dose rate, and others variables related to the irradiation conditions. Anthropogenic sources have been responsible for introducing high levels of chemical elements and compounds into the environment, many of this through the industrial waste waters. This is an issue of global concern, with potential impact on human health and the environment. IAEA recognizes the potentiality of radiation technology to clean up waste discharges, and since 2003 IAEA participate in this project. Although this is a multidisciplinary project, by the physical point of view the main objective is to characterize the most efficient electron (by intercomparison with gamma) beam, obtaining the better irradiation geometry, to implement waste water (originated in hospitals, food industry ...) treatments. Until now, we've characterized electron beams with Ionometric and fricke dosimetry at non-standard irradiation conditions, in commercial Linacs for radiotherapy purposes. We used a Varian Clinac 2100 CD, with the special TBI ETRAY conditions and nominal dose rate of 1000 UM/min, and an Elekta Digital Precise with nominal dose rate of 400 UM/min. The better dose rates obtained in water were approximately equal to 1.4 kGy/h and 0.7 kGy/h, respectively. The impact of the radiation has been studied microbiologically, toxicologically and chemically, and the evaluation between this kind of radiation and cobalt gamma radiation is also carried out at the same time. The results obtained until know and the continuous support of the IAEA experts in the project, indicates that this project will contribute to a better quality of the Portuguese industrial or hospital complexes, minimising the impact of pollutants on the environment.info:eu-repo/semantics/publishedVersio

Theory and applications of NMR-based metabolomics in human disease diagnosis

Metabolomics is a dynamic and emerging research field, joining proteomics, transcriptomics and genomics in affording a comprehensive understanding of biological systems and how these systems are affected by environmental stimuli and/or genetic modification. Metabolomics is particularly helpful for identifying biomarkers of disease processes such as the effects of a high fat diet on cardiovascular disease, providing insight into the interaction between genes and diet. Nuclear Magnetic Resonance (NMR) and Mass spectrometry (MS) are the most common analytical tools in metabolomics research. The high reproducibility of NMR-based techniques makes it superior to other analytical techniques especially in terms of searching for new and novel biomarkers in human diseases. Recently, NMR-based metabolomics approaches have been proposed as a promising and powerful technique for diagnosis of several human diseases. They have been used to investigate a wide range of diseases, through the examination of different kinds of human samples, including urine, blood plasma/serum, blister fluid, saliva, as well as intact tissue biopsies and tissue extracts. However, several factors can influence the metabolic balance within the human body and therefore in samples drawn from the body, including gender, age, fasting, diet, emotional stress, drug administration, physical activity and life style, thus complicating the use of NMR-based metabolomics approaches in diagnosing specific human disease. This chapter highlights the potential applications of NMR-based metabolomics approaches as a promising technique for diagnosis of human diseases.Metabolomics is a dynamic and emerging research field, joining proteomics, transcriptomics and genomics in affording a comprehensive understanding of biological systems and how these systems are affected by environmental stimuli and/or genetic modification. Metabolomics is particularly helpful for identifying biomarkers of disease processes such as the effects of a high fat diet on cardiovascular disease, providing insight into the interaction between genes and diet. Nuclear Magnetic Resonance (NMR) and Mass spectrometry (MS) are the most common analytical tools in metabolomics research. The high reproducibility of NMR-based techniques makes it superior to other analytical techniques especially in terms of searching for new and novel biomarkers in human diseases. Recently, NMR-based metabolomics approaches have been proposed as a promising and powerful technique for diagnosis of several human diseases. They have been used to investigate a wide range of diseases, through the examination of different kinds of human samples, including urine, blood plasma/serum, blister fluid, saliva, as well as intact tissue biopsies and tissue extracts. However, several factors can influence the metabolic balance within the human body and therefore in samples drawn from the body, including gender, age, fasting, diet, emotional stress, drug administration, physical activity and life style, thus complicating the use of NMR-based metabolomics approaches in diagnosing specific human disease. This chapter highlights the potential applications of NMR-based metabolomics approaches as a promising technique for diagnosis of human diseases.B

Prediction of treatment response of head and neck cancers by 31P MRS from pretreatment relative phosphomonester levels

NRC publication: Ye