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Vitreous and crystalline phosphate high level waste matrices: Present status and future challenges
Ashish Bohre,Kalpana Avasthi,Vladimir I. Pet’kov 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.50 No.-
Vitrification is currently the most effective process for immobilization of nuclear waste. However,ubiquitous borosilicate glass is not suitable for immobilization of nuclear waste from advanced reactorssuch as Fast Breeder Reactors (FBR) because solubility of many compounds/elements existing in the spentfuel in borosilicate glasses is quite poor. In order to possess a viable immobilization strategy for wastesarising from advanced reactors, alternatives to borosilicate glasses such as phosphate glasses, glassceramicsand crystalline waste forms are being investigated. This review aims to provide an overview ofnuclear waste immobilization employing phosphate-based glasses, glass-ceramics and crystallineceramic hosts, focusing on structure and properties that make these new matrices suitable for thechallenging task of waste immobilization.
VLS-like growth and characterizations of dense ZnO nanorods grown by e-beam process
Agarwal, D C,Chauhan, R S,Avasthi, D K,Sulania, I,Kabiraj, D,Thakur, P,Chae, K H,Chawla, Amit,Chandra, R,Ogale, S B,Pellegrini, G,Mazzoldi, P Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.3
<P>We present a new approach to produce ZnO nanorods in a reproducible manner at a temperature lower than other physical vapour deposition techniques, such as the vapour–liquid–solid mechanism. Arrays of well-aligned ZnO nanorods of uniform diameter have been synthesized on the Si substrate precoated with Au, using a simple electron beam evaporation method without the flow of any carrier gas. Scanning electron microscopy and atomic force microscopy characterizations show that as-grown nanorods are well aligned and uniform in diameter. X-ray diffraction measurements and clear lattice fringes in high-resolution transmission electron microscopy image show the growth of good quality polycrystalline hexagonal ZnO nanorods and a 〈0 0 2〉 growth direction. The polarization-dependent studies of near edge x-ray absorption fine structure (NEXAFS) are performed to investigate the electronic structure of the zinc and oxygen ions. The analysis of NEXAFS spectra at different angles of incidence of photon flux indicates the formation of ZnO nanorods having anisotropic behaviour of O and Zn states. The photoluminescence spectrum exhibits strong ultraviolet emission at 385 nm and the UV–visible spectrum also shows a band-gap transition around 390 nm indicating the good quality of nanorods. The catalytic growth mechanism of the ZnO nanorods is discussed on the basis of experimental results in this work.</P>
Vineet Kumar Singh,Jampana Nagaraju,Sushobhan Avasthi 한국물리학회 2019 Current Applied Physics Vol.19 No.3
We demonstrate radial p-n junction silicon solar cells with micro-pillar array with higher short-circuit current and open-circuit voltage than comparable planar silicon solar cells. Micro-pillar array, fabricated by RIE, acts as an effective anti-reflection coating for visible light with less than 6% reflection. Compared to devices with planar surface, devices with micro-pillar array show a 27% enhancement in short circuit current. The radial p-n junction of the micro-pillars also improves extraction probability of the photogenerated carriers, which further increases the short circuit current. Typically, micro-pillar solar cells suffer from high recombination losses at the Si/metal interface, resulting in poor VOC. Our devices prevent these recombination losses by planarizing the Si/ metal interface, leading to an open circuit voltage of 622 mV, the highest ever reported for micro-pillar solar cells. This planarized contact also reduces the series resistance associated with radial junctions, leading to series resistance of ≤0.50 Ω-cm2 and fill factors up to 76.7%.
Arun Singh Chouhan,Naga Prathibha Jasti,Shreyash Hadke,Srinivasan Raghavan,Sushobhan Avasthi 한국물리학회 2017 Current Applied Physics Vol.17 No.10
Spin coated perovskite thin films are known to have an issue of pinholes & poor morphology control which lead to poor device-to-device repeatability, that is an impediment to scale-up. In this work, Methylamine vapor annealing process is demonstrated which consistently leads to high-quality perovskite thin-films with an average grain-size of 10e15 mm. The improvement in film morphology enables improvement in effective carrier recombination lifetime, from 21 ms in as-deposited films to 54 ms in vapor-annealed films. The annealed films with large-grains are also more stable in ambient conditions. Devices made on annealed perovskite films are very consistent, with a standard deviation of only 0.7%. Methylamine vapor annealing process is a promising method of depositing large-grain CH3NH3PbI3 films with high recombination lifetime and the devices with improved performance.
R.R. Ahire,Abhay A. Sagade,S.D. Chavhan,V. Huse,F. Singh,D.K. Avasthi,D.M. Phase,Ramphal Sharma 한국물리학회 2009 Current Applied Physics Vol.9 No.3
Modified chemical bath deposited (MCBD) bismuth sulphide (Bi2S3) thin films’ structural, optical and electrical properties are engineered separately by annealing in air for 1 h at 300 ℃ and irradiating with 100 MeV Au swift heavy ions (SHI) at 5 × 1012 ions/㎠ fluence. It is observed that the band gap of the films gets red shifted after annealing and irradiation from pristine (as deposited) films. In addition, there is an increase in the grain size of the films due to both annealing and irradiation, leading to the decrease in resistivity and increase in thermoemf of the films. These results were explained in the light of thermal spike model. Modified chemical bath deposited (MCBD) bismuth sulphide (Bi2S3) thin films’ structural, optical and electrical properties are engineered separately by annealing in air for 1 h at 300 ℃ and irradiating with 100 MeV Au swift heavy ions (SHI) at 5 × 1012 ions/㎠ fluence. It is observed that the band gap of the films gets red shifted after annealing and irradiation from pristine (as deposited) films. In addition, there is an increase in the grain size of the films due to both annealing and irradiation, leading to the decrease in resistivity and increase in thermoemf of the films. These results were explained in the light of thermal spike model.
Shih-Ku Lin,Shu-Yu Yang,Seon-Cheol Park,Ok-Jin Jang,Xiaomin Zhu,Yu-Tao Xiang,Wen-Chen Ouyang,Afzal Javed,M. Nasar Sayeed Khan,Sandeep Grover,Ajit Avasthi,Roy Abraham Kallivayalil,Kok Yoon Chee,Norliza 대한정신약물학회 2022 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.20 No.1
Objective: Pharmacotherapy including mood stabilizers and antipsychotics are frequently used in bipolar disorder (BD); however, the lack of consensus regarding the definition of polypharmacy hinders conducting comparative studies across different settings and countries. Research on Asian Prescription Pattern (REAP) is the largest and the longest lasting international collaborative research in psychiatry in Asia. The objective of REAP BD was to investigate the prescription patterns of psychotropic medications across Asian countries. The rates of polypharmacy and psychotropic drug load were also analyzed. Methods: The data collection was web-based. Prescription patterns were categorized as (1) mood stabilizer monotherapy: one mood stabilizer; (2) antipsychotic monotherapy: one antipsychotic; (3) simple polypharmacy: one mood stabilizer and one antipsychotic; and (4) complex polypharmacy: ≥ 2 mood stabilizers or/and antipsychotics. The psychotropic drug load in each patient was calculated using the defined daily dose method. Results: Among 2003 patients with BD (52.1% female, 42.4 years) from 12 countries, 1,619 (80.8%) patients received mood stabilizers, 1,644 (82.14%) received antipsychotics, and 424 (21.2%) received antidepressants, with 14.7% mood stabilizer monotherapy, 13.4% antipsychotic monotherapy, 48.9% simple polypharmacy, 20.3% complex polypharmacy, and 2.6% other therapy. The average psychotropic drug load was 2.05 ± 1.40. Results varied widely between countries. Conclusion: Over 70% of psychotropic regimens involved polypharmacy, which accords with the high prevalence of polypharmacy in BD under a permissive criterion (2 or more core psychotropic drugs) worldwide. Notably, ≥ 80% of our sample received antipsychotics, which may indicate an increasing trend in antipsychotic use for BD treatment.
A Call for a Rational Polypharmacy Policy: International Insights From Psychiatrists
Yukako Nakagami,Kohei Hayakawa,Toru Horinouchi,Victor Pereira-Sanchez,Marcus P,J,Tan,Seon-Cheol Park,Yong Chon Park,Seok Woo Moon,Tae Young Choi,Ajit Avasthi,Sandeep Grover,Roy Abraham Kallivayalil,Yu 대한신경정신의학회 2021 PSYCHIATRY INVESTIGATION Vol.18 No.11
Objective Recently, rational polypharmacy approaches have been proposed, regardless of the lower risk and cost of monotherapy. Considering monotherapy as first-line treatment and polypharmacy as rational treatment, a balanced attitude toward polypharmacy is recommended. However, the high prevalence of polypharmacy led the Japanese government to establish a polypharmacy reduction policy. Based on this, the association between the policy and psychiatrists’ attitude toward polypharmacy has been under debate. Methods We developed an original questionnaire about Psychiatrists’ attitudes toward polypharmacy (PAP). We compared the PAP scores with the treatment decision-making in clinical case vignettes. Multiple regression analyses were performed to quantify associations of explanatory variables including policy factors and PAP scores. The anonymous questionnaires were administered to psychiatrists worldwide. Results The study included 347 psychiatrists from 34 countries. Decision-making toward polypharmacy was associated with high PAP scores. Multiple regression analysis revealed that low PAP scores were associated with the policy factor (β=-0.20, p=0.004). The culture in Korea was associated with high PAP scores (β=0.34, p<0.001), whereas the culture in India and Nepal were associated with low scores (β=-0.15, p=0.01, and β=-0.17, p=0.006, respectively). Conclusion Policy on polypharmacy may influence psychiatrists’ decision-making. Thus, policies considering rational polypharmacy should be established.