320 research outputs found
Study on the Effect of Fe3O4 Nanoparticle Dopants on the Properties of Magneto Optical Glasses
No full textEffect of magnetite nanoparticles doped glass with enhanced Verdet constant for magnetic optical current transducer applications
No full text. Fe3O4 nanoparticles were synthesized and doped into two glass systems (Na2O-B2O3 glass and PbO-Bi2O3-B2O3-GeO2 glasses) at low concentrations using traditional glass melting method. The formation of Fe3O4 nanoparticles was obtained through coprecipitation of Fe(II) and Fe(III) in alkaline media.The size of the Fe3O4 nanoparticles was observed to be around 15 nm. The structure and properties of doped glasses were studied by X-ray diffraction (XRD), scanning electric microscope (SEM), UV-VIS spectray, FT-IR spectray analysis and Faraday rotation test. Compared to the host glass, Fe3O4 nanoparticles doped glasses shown enhanced Faraday Effect in term of Verdet constant and will have potential application in magneto-optical devices.</jats:p
Non-enzymatic glucose sensor based on hierarchical Au/Ni/boron-doped diamond heterostructure electrode for improving performances
No full textA novel hierarchical Au/Ni/boron-doped diamond (BDD) heterostructure electrode was fabricated by two-step heat-treatment. The heterostructure that hierarchical Au/Ni nanoparticles are embedded on the surface of BDD was demonstrated by transmission electron microscope (TEM). Cyclic voltammetry (CV) and amperometric detection were used to test electrochemical properties of the prepared electrodes. The Au/Ni/BDD electrode exhibited enhanced catalytic activity and stability in glucose detection, as compared to that of the Au/BDD and Ni/BDD electrodes. On the optimal NaOH concentration and applied potential, the Au/Ni/BDD electrode exhibited an extremely wide detection range of 0.005-32 mM with high sensitivity of 1229.5 μAmM−1cm−2 and an excellent long-term stability (maintains 94.8% of initial current after one month). In addition, the prepared electrode also exhibited a low detection limit of 2 μM (S/N = 3), good selectivity and reproducibility. At last, the reasons for enhanced catalytic activity and excellent stability of Au/Ni/BDD electrode were discussed.</p
Long-term stability of Au nanoparticle-anchored porous boron-doped diamond hybrid electrode for enhanced dopamine detection
No full textA porous boron-doped diamond (pBDD) was made for immobilizing gold nanoparticles on BDD facets by a special process, wherein methods of magnetron sputtering and thermal catalytic treatment were utilized. Au nanoparticles are seated in the pores of pBDD facets and could be more stable during electrochemical tests. This hybrid structure significantly improved the electrochemical properties due to the introduction of Au nanoparticles and pores, which could increase the specific surface area. The cyclic voltammetry oxidation peak current of the Au/pBDD electrode decreased with an average daily loss of 0.02 μA and maintained approximately 90.1% of its initial value after detecting dopamine once per two days for 30 days, showing an excellent long-term electrochemical stability. In addition, the Au/pBDD electrode exhibited excellent sensitivity for the detection of DA, and the limit of detection was 0.06 μM in a linear concentration range of 0.1 μM–1 mM. This work indicates that the Au/pBDD is an appropriate material for detecting DA in a long-term tests.</p
Constructing a Vocational Mathematics Teaching Model Aligned with Industry Needs
No full textWith the increasing integration of vocational education and industry, the content and methodology of vocational mathematics courses require systematic restructuring. Based on the context of industry-education integration, this paper analyzes the current issues in vocational mathematics teaching and proposes a reform pathway oriented toward job competencies and rooted in real-world application scenarios. The study advocates for enterprise participation in curriculum design, task-driven instruction, and the cultivation of data analysis capabilities to achieve a seamless connection between mathematical knowledge and vocational skills. Empirical research indicates that this teaching model effectively enhances students’ learning motivation, practical abilities, and job adaptability, providing a valuable reference for the development of vocational mathematics curricula
Highly Sensitive and Selective Potassium Ion Detection Based on Graphene Hall Effect Biosensors
No full textPotassium (K+) ion is an important biological substance in the human body and plays a critical role in the maintenance of transmembrane potential and hormone secretion. Several detection techniques, including fluorescent, electrochemical, and electrical methods, have been extensively investigated to selectively recognize K+ ions. In this work, a highly sensitive and selective biosensor based on single-layer graphene has been developed for K+ ion detection under Van der Pauw measurement configuration. With pre-immobilization of guanine-rich DNA on the graphene surface, the graphene devices exhibit a very low limit of detection (approximate to 1 nM) with a dynamic range of 1 nM-10 mu M and excellent K+ ion specificity against other alkali cations, such as Na+ ions. The origin of K+ ion selectivity can be attributed to the fact that the formation of guanine-quadruplexes from guanine-rich DNA has a strong affinity for capturing K+ ions. The graphene-based biosensors with improved sensing performance for K+ ion recognition can be applied to health monitoring and early disease diagnosis
L'étude du principe de moindre action pour systèmes mécaniques dissipatifs, et la probabilité de chemins du mouvement mécanique aléatoire
No full textThe present thesis is devoted to the study of path probability of random motion on the basis of an extension of Hamiltonian/Lagrangian mechanics to stochastic dynamics. The path probability is first investigated by numerical simulation for Gaussian stochastic motion of non dissipative systems. This ideal dynamical model implies that, apart from the Gaussian random forces, the system is only subject to conservative forces. This model can be applied to underdamped real random motion in the presence of friction force when the dissipated energy is negligible with respect to the variation of the potential energy. We find that the path probability decreases exponentially with increasing action, i.e., P(A) ~ eˉγA, where γ is a constant characterizing the sensitivity of the action dependence of the path probability, the action is given by A = ∫T0 Ldt, a time integral of the Lagrangian L = K–V over a fixed time period T, K is the kinetic energy and V is the potential energy. This result is a confirmation of the existence of a classical analogue of the Feynman factor eiA/ħ for the path integral formalism of quantum mechanics of Hamiltonian systems. The above result is then extended to real random motion with dissipation. For this purpose, the least action principle has to be generalized to damped motion of mechanical systems with a unique well defined Lagrangian function which must have the usual simple connection to Hamiltonian. This has been done with the help of the following Lagrangian L = K – V – Ed, where Ed is the dissipated energy. By variational calculus and numerical simulation, we proved that the action A = ∫T0 Ldt is stationary for the optimal paths determined by Newtonian equation. More precisely, the stationarity is a minimum for underdamped motion, a maximum for overdamped motion and an inflexion for the intermediate case. On this basis, we studied the path probability of Gaussian stochastic motion of dissipative systems. It is found that the path probability still depends exponentially on Lagrangian action for the underdamped motion, but depends exponentially on kinetic action A = ∫T0 Kdt for the overdamped motion.La présente thèse est consacrée à l’étude de la probabilité du chemin d’un mouvement aléatoire sur la base d’une extension de la mécanique Hamiltonienne/Lagrangienne à la dynamique stochastique. La probabilité d’un chemin est d’abord étudiée par simulation numérique dans le cas du mouvement stochastique Gaussien des systèmes non dissipatifs. Ce modèle dynamique idéal implique que, outre les forces aléatoires Gaussiennes, le système est seulement soumis à des forces conservatrices. Ce modèle peut être appliqué à un mouvement aléatoire réel de régime pseudo-périodique en présence d’une force de frottement lorsque l’énergie dissipée est négligeable par rapport à la variation de l’énergie potentielle. Nous constatons que la probabilité de chemin décroît exponentiellement lorsque le son action augmente, c’est à dire, P(A) ~ eˉγA, où γ est une constante caractérisant la sensibilité de la dépendance de l’action à la probabilité de chemin, l’action est calculée par la formule A = ∫T0 Ldt, intégrale temporelle du Lagrangien. L = K–V sur une période de temps fixe T, K est l’énergie cinétique et V est l’énergie potentielle. Ce résultat est une confirmation de l’existence d’un analogue classique du facteur de Feynman eiA/ħ pour le formalisme intégral de chemin de la mécanique quantique des systèmes Hamiltoniens. Le résultat ci-dessus est ensuite étendu au mouvement aléatoire réel avec dissipation. A cet effet, le principe de moindre action doit être généralisé au mouvement amorti de systèmes mécaniques ayant une fonction unique de Lagrange bien définie qui doit avoir la simple connexion habituelle au Hamiltonien. Cela a été fait avec l’aide du Lagrangien suivant L = K − V − Ed, où Ed est l’énergie dissipée. Par le calcul variationnel et la simulation numérique, nous avons prouvé que l’action A = ∫T0 Ldt est stationnaire pour les chemins optimaux déterminés par l’équation newtonienne. Plus précisément, la stationnarité est un minimum pour les mouvements de régime pseudo-périodique, un maximum pour les mouvements d’amortissement apériodique et une inflexion dans le cas intermédiaire. Sur cette base, nous avons étudié la probabilité du chemin du mouvement stochastique Gaussien des systèmes dissipatifs. On constate que la probabilité du chemin dépend toujours de façon exponentielle de l’action Lagrangien pour les mouvements de régime pseudo-périodique, mais dépend toujours de façon exponentielle de l’action cinétique A = ∫T0 Kdt pour régime apériodique
Effect of mixed salts electrolyte on high temperature performance in LiNi1/3Co1/3Mn1/3O2 batteries
No full textmiR-300 rs12894467 polymorphism may be associated with susceptibility to primary lung cancer in the Chinese Han population
No full textZhiqiang Liu,1,2 Yong Lin,3 Shuling Kang,4 Qiuping Xu,2 Weimin Xiong,2 Lin Cai,2 Fei He2,5 1The United Innovation of Mengchao Hepatobiliary Technology Key Laboratory of Fujian Province, Mengchao Hepatobiliary Hospital of Fujian Medical University, Fuzhou, Fujian, China; 2Department of Epidemiology and Health Statistics, School of Public Health, Fujian Medical University, Fuzhou, Fujian, China; 3Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen, Fujian, China; 4Fuzhou Center for Disease Control and Prevention, Fuzhou, Fujian, China; 5Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, Fujian, China Objective: The etiology of lung cancer has been attributed to both environmental and genetic factors. In this study, we investigated the association between five miRNA gene single-nucleotide polymorphisms (SNPs) and the risk of lung cancer, and explored the interaction between genetic and environmental factors in the Han people of China, the ethnic group that represents >90% of the population of the country.Methods: This case–control study included 1,067 cases and 1,085 controls. Epidemiological data were collected by in-person interviews using a standard questionnaire. Matrix-assisted laser desorption/ionization time of flight mass spectrometry was applied to genotype the selected miRNA gene SNPs. Unconditional logistic regression and stratified analysis were used to analyze the associations between these SNPs and lung cancer, and to calculate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Crossover analysis, logistic regression, and the Excel table made by Andersson were used to analyze the combined and interaction effects of gene–environment.Results: The rs12894467 CC/CT genotype was associated with a significantly increased risk for lung cancer in women (adjusted OR =1.46, 95% CI=1.01–2.10). Smokers carrying the CC/CT genotype were associated with a significantly decreased risk of lung cancer, the adjusted OR was 0.75 (95% CI: 0.57–0.98). In the dominant model, rs12894467 and gender were associated with a positive multiplicative interaction; rs12894467 and smoking were associated with a negative multiplicative interaction.Conclusion: The rs12894467 polymorphism was potentially associated with primary lung cancer in the Han Chinese population and had an interactive relationship with environmental factors. Keywords: microRNAs, single-nucleotide polymorphism, lung cancer, case–control studies, susceptibilit
Effect of magnetic and electric coupling fields on micro- and nano-structure of carbon films in the CVD diamond process and their electron field emission property
No full textIn this paper, both electric field and magnetic field were used to assist the hot filament chemical vapor deposition (HFCVD) and we systematically investigated the effects of which on the (1) phase composition, (2) grain size, (3) thickness and (4) preferred orientation of diamond films through SEM, Raman and XRD. The application of magnetic field in electric field, so called 'the magnetic and electric coupling fields', enhanced the graphitization and refinement of diamond crystals, slowed down the decrease of film thickness along with the increase of bias current, and suppressed diamond (100) orientation. During the deposition process, the electric field provided additional energy to HFCVD system and generated large number of energetic particles which might annihilate at the substrate and lose kinetic energy, while the Lorentz force, provided by magnetic field, could constrict charged particles (including electrons) to do spiral movement, which prolonged their moving path and life, thus the system energy increased. With the graphitization of diamond films intensified, the preferred orientation of diamond films completely evolved from (110) to (100), until the orientation and diamond phase disappeared, which can be attributed to (I) the distribution and concentration ratio of carbon precursors (C2H2 and CH3) and (II) graphitization sequence of diamond crystal facets. Since the electron field emission property of carbon film is sensitive to the phase composition, thickness and preferred orientation, nano-carbon cones, prepared by the negative bias current of 20 mA and magnetic field strength of 80 Gauss, exhibited the lowest turn-on field of 6.1 V-1 mu m(-1)
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