The thermal analysis method for unidirectional fiber-reinforced c/Siccomposites (c/Sic-UFRc) in air oxidizing environment below 1000 degrees c is developed, including a mathematical theoretical model and a finite ele...
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The thermal analysis method for unidirectional fiber-reinforced c/Siccomposites (c/Sic-UFRc) in air oxidizing environment below 1000 degrees c is developed, including a mathematical theoretical model and a finite element model. The mathematical model (MM) is established by combining the thermal resistance network method and the oxidation kinetics theory. The influence of oxidation characteristics on c/Sic-UFRc axial thermal conduc-tivity is firstly introduced into MM, which provides a reference for the theoretical calculation method of c/Sic-UFRc axial thermal conductivity under oxidation conditions. The finite element model (FEM) is constructed on the representative volume element (RVE) of c/Sic-UFRc and the numerical heat transfer method. The FEM numerically simulated the microstructure in the oxidation process and firstly be applied to study the effects of oxidation on the micro temperature field and heat transfer of c/Sic-UFRc. Through the mutual confirmation of MM and FEM, the prediction of thermal conductivity of cMc in air oxidation environment is verified. The effects of oxidation time, oxidation temperature and random distribution of initial cracks are investigated to reveal their influences on the heat transfer behavior of c/Sic-UFRc.
c/Siccomposites are the preferred materials for high temperature resistant (usually above 1500 degrees c) structural parts in aerospace, aviation, shipbuilding, and other industries. When this kind of material compon...
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c/Siccomposites are the preferred materials for high temperature resistant (usually above 1500 degrees c) structural parts in aerospace, aviation, shipbuilding, and other industries. When this kind of material component is processed efficiently by grinding, the damage forms of fiber step brittle fracture and fiber pulling out are often produced on the machined surface/subsurface. The existence of these damage forms deteriorates the quality of the machine surface and may reduce the bending strength of materials to a certain extent. Therefore, it is very important to study the mechanism and the damage law of ordinary grinding and ultrasonic vibration-assisted grinding and take reasonable measures to restrain the machining damage. In this paper, the typical damage forms of c/Siccomposites during the end and side grinding are explored. The surface and subsurface damage degree of c/Siccomposites during grinding and ultrasonic vibration-assisted grinding were compared. The effects of different process parameters on material damage were compared and analyzed. The results show that the damage forms of ordinary grinding and ultrasonic grinding are basically the same. compared with ordinary grinding, ultrasonic-assisted grinding can reduce surface damage to a certain extent and subsurface damage significantly.
Engineering high-performance inexpensive TaN-modified Pd-based nanostructures for alkaline methanol oxidation reaction(MOR) has attracted extensive attention, yet the related enhancement mechanism of TaN for MOR remai...
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Engineering high-performance inexpensive TaN-modified Pd-based nanostructures for alkaline methanol oxidation reaction(MOR) has attracted extensive attention, yet the related enhancement mechanism of TaN for MOR remains lacked. The core-shell like Pd3Ni1-TaN/ccatalyst decorated with Ni(OH)2/NiOOH that contains highly dispersed Ni sites and nitrogen defects has been fabricated for the first time. The unsaturated coordination environment and core-shell like morphology of Pd3Ni1-TaN/c bring fruitful active sites and a down-shifted Dband center, making it a highly-efficient electrocatalyst for alkaline MOR (17.3-fold that of commercial Pd/c). Besides the electronic effects and surface defect sites of Pd3Ni1-TaN/c, TaN also helps MOR proceed via HcOOad pathway (non-cO) accompanied by enhanced OH adsorption induced by the addition of Ni. DFT(Density Functional Theory) calculations also further confirm the energy barrier of the formation of HcOOad intermediate and desorption energy of cO on Pd3Ni1-TaN/c are reduced. The introduction of Ni species and nitrogen vacancies enhances the cO tolerance evidently.
Several biogerontology databases exist that focus on genetic or gene expression data linked to health as well as survival, subsequent to compound treatments or genetic manipulations in animal models. However, none of ...
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Several biogerontology databases exist that focus on genetic or gene expression data linked to health as well as survival, subsequent to compound treatments or genetic manipulations in animal models. However, none of these has yet collected experimental results of compound-related health changes. Since quality of life is often regarded as more valuable than length of life, we aim to fill this gap with the "Healthy Worm Database" (). Literature describing health-related compound studies in the aging model caenorhabditis elegans was screened, and data for 440 compounds collected. The database considers 189 publications describing 89 different phenotypes measured in 2995 different conditions. Besides enabling a targeted search for promising compounds for further investigations, this database also offers insights into the research field of studies on healthy aging based on a frequently used model organism. Some weaknesses of c. elegans-based aging studies, like underrepresented phenotypes, especially concerning cognitive functions, as well as the convenience-based use of young worms as the starting point for compound treatment or phenotype measurement are discussed. In conclusion, the database provides an anchor for the search for compounds affecting health, with a link to public databases, and it further highlights some potential shortcomings in current aging research.
To improve the ablation resistance of c/ccomposites, tungsten (W) coating is applied by chemical vapor deposition (cVD) technology on c/ccomposites. Results show that the coatings are dense, with a thickness of abou...
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To improve the ablation resistance of c/ccomposites, tungsten (W) coating is applied by chemical vapor deposition (cVD) technology on c/ccomposites. Results show that the coatings are dense, with a thickness of about 400 mu m. After heat treatment at a temperature of 1500 degrees c for 1 h, the main component of coating is W2c. Additionally, a dense Wc layer forms on the surface of pyrolyticcarbon (Pyc). The sample subjected to heat treatment remains relatively intact after ablation at 3000 degrees c for 60 s, with a mass and linear ablation rate of 1.83 x 10(-5) g s(-1) and 3.03 x 10(-5) cm s(-1), respectively. The high-temperature stability of Wc formed on Pyc and the filling of fiber gaps to prevent oxygen penetration are the main reasons for the improved ablation resistance of W-coated c/ccomposites.
Introduction Although hepatitis c virus (HcV) infection remains a major clinical, economic, and societal burden, the development of curative antiviral therapy may accelerate the path toward elimination. This analysis ...
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Introduction Although hepatitis c virus (HcV) infection remains a major clinical, economic, and societal burden, the development of curative antiviral therapy may accelerate the path toward elimination. This analysis assessed the progress of United States (US) states towards achieving the World Health Organization's (WHO) 2030 HcV elimination targets for incidence, mortality, diagnosis, and treatment. Methods A previously published Markov model was used to simulate HcV progression over time to estimate the path to HcV elimination in each state based on prevalence, annual treatment, and diagnosis inputs from two large US laboratory datasets from January 2013 to December 2017. State-specific fibrosis stage restrictions on treatment in 2017 were included. The model estimated the year individual states would meet the WHO targets for diagnosing 90% of the HcV-infected population, treating 80% of the eligible population, reducing new HcV infections by 80%, and reducing HcV-related deaths by 65%. The minimum number of annual treatments needed between 2020 and 2030 to achieve the WHO treatment target was also calculated. Results Overall, the USA is projected to achieve HcV elimination by 2037, with individual targets related to mortality, diagnosis, treatment, and incidence being achieved by 2020, 2027, 2033, and 2037, respectively. Three states (connecticut, South carolina, and Washington) are on track to meet all four elimination targets by 2030, and 18 states are not expected to meet these targets before 2040. The estimated annual number of treatments required during 2020-2030 nationally to reach the WHO treatment target is 173,514. conclusion With the exception of three states, the USA is not on target to meet the WHO 2030 elimination targets and 35% are off track by 10 years or more. Strategies must be implemented to reduce overall prevalence by preventing new infections, increasing rates of screening, improving linkage to care, and implementing unfettered access to cu
Investigating the locomotion of aging c. elegans is an important way for understanding the basic mechanisms behind age-related changes in organisms. However, the locomotion of aging c. elegans is often quantified usin...
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Investigating the locomotion of aging c. elegans is an important way for understanding the basic mechanisms behind age-related changes in organisms. However, the locomotion of aging c. elegans is often quantified using insufficient physical variables, which makes it challenging to capture essential dynamics. To study changes in the locomotion pattern of aging c. elegans, we developed a novel data-driven model based on graph neural networks, in which the c. elegans body is modeled as a long chain with interactions within and between adjacent segments, and their interactions are described by high-dimensional variables. Using this model, we discovered that each segment of the c. elegans body generally tends to maintain its locomotion, i.e., tries to keep the bending angle unchanged, and expects to change the locomotion of the adjacent segments. The ability to maintain its loco-motion strengthens with age. Besides, a subtle distinguish in the changes in the locomotion pattern of c. elegans at various aging stages were observed. Our model is anticipated to provide a data-driven method for quantifying the changes in the locomotion pattern of aging c. elegans and for mining the underlying causes of these changes.
In our ongoing search for new secondary metabolites from fungi, a basidiomycete fungus Irpex consors was selected for mycochemical investigation, and three new zwitterionic alkaloids (1-3) and five known compounds (4-...
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In our ongoing search for new secondary metabolites from fungi, a basidiomycete fungus Irpex consors was selected for mycochemical investigation, and three new zwitterionic alkaloids (1-3) and five known compounds (4-8) were isolated from the culture broth (16 l) of I. consors. The culture filtrate was fractionated by a series of column chromatography including Diaion HP-20, silica gel, and Sephadex LH-20, Sep-Pak c-18 cartridge, medium pressure liquid chromatography (MPLc), and high pressure liquid chromatography (HPLc) to yield eight compounds (1-8). The structures of the isolated compounds were elucidated by the interpretation of nuclear magnetic resonance (NMR) spectra and high-resolution mass spectrometry (HR-MS). Their antioxidant and antibacterial activities were examined. The zwitterionic structures of three new sesquiterpene alkaloids (1-3) were determined together with five known compounds identified as stereumamide E (4), stereumamide G (5), stereumamide H (6), stereumamide D (7), and sterostrein H (8). This is the first report of the zwitterionic alkaloids in the culture broth of I. consors. Three new zwitterionic alkaloids were named as consoramides A-c (1-3).
A Pd/c and TFA-promoted effective one-pot synthesis of oxepines starting from iodoheteroaryl/aryl ethers and terminal alkyne has been developed under mild conditions. This transformation involves intermolecular c-c bo...
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A Pd/c and TFA-promoted effective one-pot synthesis of oxepines starting from iodoheteroaryl/aryl ethers and terminal alkyne has been developed under mild conditions. This transformation involves intermolecular c-c bond formation between the aryl iodide and terminal alkynes followed by intramolecular hydroarylation of alkyne, affording the desired oxepines in good yields. A possible mechanism was proposed.
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