Report on chemical impurities in lots of 2020 graphite

Chemical and physical studies on agglomerated and dispersed impurities found in three lots of 2020 graphite received from the Stackpole Company are described. Each lot consisted of three billets, one shipment of off-the-shelf 2020 and two of ``nuclear quality`` graphite for which efforts had been taken to decrease impurity levels. An earlier report described the results of chemical analyses of the three lots of graphite and the gross distribution of the impurities in the billets. The present report describes the chemical and physical studies on the detailed distribution and chemical identity of the agglomerates that led to the identification of their source. Agglomerated impurities were found in all lots of 2020. The particles possessed an average size range of about 0.3 mm. In addition to these particulates, other inorganic ash forming components were found to be rather more uniformly distributed internally throughout the graphite. 4 refs., 4 figs., 3 tabs

(Terminology standardization)

Terminological requirements in information management was but one of the principal themes of the 2nd Congress on Terminology and Knowledge Engineering. The traveler represented the American Society for Testing and Materials' Committee on Terminology, of which he is the Chair. The traveler's invited workshop emphasized terminology standardization requirements in databases of material properties as well as practical terminology standardizing methods. The congress included six workshops in addition to approximately 82 lectures and papers from terminologists, artificial intelligence practitioners, and subject specialists from 18 countries. There were approximately 292 registrants from 33 countries who participated in the congress. The congress topics were broad. Examples were the increasing use of International Standards Organization (ISO) Standards in legislated systems such as the USSR Automated Data Bank of Standardized Terminology, the enhanced Physics Training Program based on terminology standardization in Physics in the Chinese province of Inner Mongolia, and the technical concept dictionary being developed at the Japan Electronic Dictionary Research Institute, which is considered to be the key to advanced artificial intelligence applications. The more usual roles of terminology work in the areas of machine translation. indexing protocols, knowledge theory, and data transfer in several subject specialties were also addressed, along with numerous special language terminology areas

Formation and use of oxide films to impede outgassing of metals

From surface effects in controlled thermonuclear fusion devices and reactors meeting; Argorne, Illinois, USA (10 Jan 1974). Phenomena associated with the outgassing of metals are generally interpreted using models bascd either on desorption of compounds from the surface or on diffusion of dissolved gases from the interior of the metal. It is generally recognized that surface oxide films can serve to decrease outgassing rates of metals. However, the processes associnted with the outgassing of oxidized or oxide-coated metals are not well understood. Cutgassing of oxidized metals is considered in light of the results of recent studies of hydrogen permeation through metals with well characterized oxide films. The chemical stabilities of the oxides as well as the physical imperfections of the film are considered. A model is suggested for the expected outgassing behavior of oxidized steels at intermediate temperatures, which are of interest in the design of controlled thermonuclear research experiments and reactors. The role of impurities and the usefulness of specialized oxidation treatments are discussed. (auth

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Vascular Remodeling in Health and Disease

The term vascular remodeling is commonly used to define the structural changes in blood vessel geometry that occur in response to long-term physiologic alterations in blood flow or in response to vessel wall injury brought about by trauma or underlying cardiovascular diseases.1, 2, 3, 4 The process of remodeling, which begins as an adaptive response to long-term hemodynamic alterations such as elevated shear stress or increased intravascular pressure, may eventually become maladaptive, leading to impaired vascular function. The vascular endothelium, owing to its location lining the lumen of blood vessels, plays a pivotal role in regulation of all aspects of vascular function and homeostasis.5 Thus, not surprisingly, endothelial dysfunction has been recognized as the harbinger of all major cardiovascular diseases such as hypertension, atherosclerosis, and diabetes.6, 7, 8 The endothelium elaborates a variety of substances that influence vascular tone and protect the vessel wall against inflammatory cell adhesion, thrombus formation, and vascular cell proliferation.8, 9, 10 Among the primary biologic mediators emanating from the endothelium is nitric oxide (NO) and the arachidonic acid metabolite prostacyclin [prostaglandin I2 (PGI2)], which exert powerful vasodilatory, antiadhesive, and antiproliferative effects in the vessel wall

Tritium permeation through steam generator materials

A model is developed for hydrogen isotope permeation through metals that have one side coated with a material through which the transport of hydrogen is directly dependent on the pressure of hydrogen. (MOW

Control of Water Absorption by Purification of Graphite

It is well known that graphite can absorb large quantities of water, which can represent an abundant source of oxygen impurities in fusion plasmas if the corresponding components are not properly outgassed. We have outgassed various fusion-relevant graphites (e.g., POCO AXF-5Q) for 1.5 h at 1500/degree/C to release absorbed water and have subsequently exposed the samples to air for various periods of time. Re-absorption of water during the air exposure was estimated by measuring the amount of water produced in subsequent outgassing runs. The results show that the amount of water re-absorbed increases by a factor of approximately 10 within 8 h compared to the sample in the outgassed state but with no air exposure. The water content of the 'as received' material is reached after approximately 30 days. Re-absorption of water was significantly reduced by purification of the investigated graphite samples. This purification process, which consists of heating the sample at 2800/degree/C for 30 min in an argon atmosphere, reduces the levels of trace impurities which can be responsible for catalytic surface reactions on the internal surfaces of the graphite. After exposing an outgassed sample to an electron cyclotron heated plasma followed by 1 h air exposure, the amount of water desorbed was observed to increase by a factor of 6. Data will be presented to correlate this effect with trace impurities. 9 refs., 2 figs., 5 tabs

Tritium permeation through materials for steam generator systems

Mixed isotope techniques and experimental apparatus have been developed for determining the rates of tritium permeation through metals at high temperatures. An inert gas or a controlled steam oxidizing atmosphere on the downstream side of the sample is used so that effects of surface oxidation and the formation of oxide coatings to impede tritium permeation can be determined. The validity of the method was demonstrated by determining the tritium permeability of nickel and comparing the tritium values to established hydrogen and deuterium permeabilities. The methods were applied in a long-term experiment by measuring tritium permeation through Incoloy 800 at 657$sup 0$C with the downstream side of the sample continuously treated with a 750 torr sweep gas of Ar--H$sub 2$O with the H$sub 2$O partial pressure at 240 torr. Oxidation of the metal to form an oxide coating on the metal was accompanied by a decrease in the tritium permeation by a factor of 160 over a period of 84 days. (auth