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Spectral change and far-red emission of Mn^(2+)ions co-doped NaSrB_(5)O_(9):Dy^(3+)luminescence material for plant growth LEDs

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Journal of Rare Earths 2022年第2期40卷 218-225,I0002页

作者： k.Munirathnam koduru Mallikarjuna R.Vijaya P.C.Nagajyothi k.ramakrishna Reddy M.Srinivas Department of Physics School of Applied SciencesREVA UniversityBengaluru560064India Department for Management of Science and Technology Development Ton Due Thang UniversityHo Chi Minh CityVietnam Faculty of Applied Sciences Ton Due Thang UniversityHo Chi Minh CityVietnam Department of Physics Visvodaya Government Degree CollegeVenkatagiri524132India School of Mechanical Engineering Yeungnam UniversityGyeongsan33541South Korea Department of Chemistry School of Applied SciencesREVA UniversityBengaluru560064India

Due to the characteristic emission of phosphors,phosphor-converted LEDs have been employed to provide the requisite light sources for indoor plant growth in the optical agricultural ***,we prepared a series of Mn^(2+)co-doped NaSrB5 O9:Dy^(3+)phosphors via a solid-state reaction *** phosphors have significant three-band emissions at 467 nm(blue region),606 nm(orange region),and765 nm(far-red region),ascribed to the^(4)F_(9/2)-^(6)H_(15/2)and 4 F9/2-6 H13/2 transitions of the Dy^(3+)ions and the^(4)T_(1g)(G)-^(6)A_(1g)(S)spin-forbidden transition of the Mn^(2+)ions,respectively,when excited by light of 376 nm(near-UV region).The co-dopant in the host material facilitates tunable photoluminescence(PL)due to energy transfer from the Dy^(3+)ions to the Mn^(2+)*** three emission peaks from the prepared phosphors well match with the absorption spectra of the photosynthesis pigments of plants,chlorophyll and phytochrome,which can absorb blue(400-500 nm),orange-red(550-700 nm),and infrared(IR)radiation,indicating that these phosphors have potential applications in the fabrication of plant-growth *** to the PL studies,the structure of the phosphors was determined by X-ray diffraction,refined by Rietveld method and chemically quantified by X-ray photoelectron spectroscopy.

关键词： Phosphors Refinement X-ray photoelectron spectroscopy Energy transfer Plant growth LEDs Rare earths

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Determination of genotoxic alkyl methane sulfonates and alkyl paratoluene sulfonates in lamivudine using hyphenated techniques

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Journal of Pharmaceutical Analysis 2012年第4期2卷 314-318页

作者： N.V.V.S.S.Raman A.V.S.S.Prasad k.Ratnakar Reddy k.ramakrishna Hetero Drugs Ltd.(R&D) GITAM Institute of Science GITAM University

Two highly sensitive methods for the determination of genotoxic alkyl methane sulfonates (AMSs) and alkyl paratoluene sulfonates (APTSs) in lamivudine using hyphenated techniques have been presented. AMSs were determined by GC-MS method using GSBPINOWAX (30 m 0.25 mm 0.25 mm) column. Temperature program was set by maintaining at 100 1C initially for 3 min, then rised to 220 1C at the rate of 15 1C/min and maintained at 220 1C for 16 min. N,N-dimethyl formamide was used as diluent. APTSs were determined by LC-MS using Zorbax, Rx C8, 250 mm 4.6 mm, 5 mm column as stationary phase. 0.01 M ammonium acetate is used as buffer. The mixture of buffer and methanol in 75:25 (v/v) ratio was used as mobile phase A and mixture of buffer and methanol in 5:95 (v/v) ratio was used as mobile phase B. The gradient program (T/%B) was set as 0/28, 16/50, 17/100, 23/100, 27/28 and 40/28. Both the methods were validated as per International Conference on Harmonization guidelines. Limit of quantitation was found 1.5 mg/mL for AMSs and was in the range of 1.0-1.5 mg/mL for APTSs.

关键词： Genotoxins Alkyl methane sulfonates Alkyl paratoluene sulfonates Lamivudine Hyphenated techniques

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Effect of embedment length of untreated natural fibres on the bond behaviour in cement mortar

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Frontiers of Structural and Civil Engineering 2018年第4期12卷 454-460页

作者： Gudimella ramakrishna Sriraman PRIYADHARSHINI Department of Civil Engineering Pondicherry Engineering CollegePuducherry 605014lndia

The present investigation is focused on studying the effects of various matrices with 1:3, 1:4 and 1:5 mortars and fibre types of sisal and coir on the bond behavior at various ages of curing, i.e., 24 h, 3 d, 7 d and 28 d. The other parameters included in the investigation are water/cement (w/c) ratio, sand gradation and embedment length of fibres. In addition, the type of failure of sisal and coir fibres for different mixes of mortars at various curing ages is also reported. From the results, it is seen that the bond strength is improving with respect to age of curing in case of sisal fibres, but decreases in case of coir fibres. The failure of fibres due to fibre fracture is observed in sisal fibres and fibre pullout is observed in coir fibres. The other varying parameters such as mortar mixes, sand gradation, w/c ratio and embedded length also showed significant effect on bond behaviour of sisal and coir fibre with the cement mortar mixes.

关键词： bond strength cement mortar natural fibre pullout test type of failure

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Stall Characteristics and Tip Clearance Effects in Forward Swept Axial Compressor Rotors

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Journal of Thermal Science 2009年第1期18卷 40-47页

作者： ramakrishna PV Govardhan M Thermal Turbomachines Laboratory Department of Mechanical EngineeringIndian Institute of Technology Madras

Tilting the blade sections to the flow direction （blade sweep） would increase the operating range of an axial compressor due to modifications in the pressure and velocity fields on the suction surface. On the other hand, blade tip gap, though finite, has great influence on the performance of a turbomachine. The present paper investigates the combined effect of these two factors on various flow characteristics iu＇a low speed axial flow compressor. For this present study, nine computational domains were modeled; three rotor sweep configurations （0°, 20° and 30°）and for three different clearance levels for each rotor. Commercial CFD solver ANSYS CFX 11.0 is used for the simulations. Results indicated that tip chordline sweep is found to improve the stall margin of the compressor by modifying the suction surface boundary layer migration phenomenon. Diffusion Factor （DF） contours showed the severity of stalling with unswept rotor. For the swept rotors, the zones of high probable stall are less severe and they become less in size with increasing sweep. Increment in the tip gap is found to gradually affect the performance of unswept rotor, while the effect is very high for the two swept rotors for the earlier increments. As a minimum clearance is unavoidable, swept rotors suffer relatively higher deviation from the idealistic behavior than the unswept rotor due to tip clearance.

关键词： Sweep Tip clearance Axial compressor Stall margin Tip leakage flows.

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Anticancer Activity of Rice Callus Suspension Cultures from Aromatic Varieties and Metabolites Regulated in Treated Cancer Cell Lines

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Rice science 2024年第4期31卷 449-462,I0027-I0030页

作者： Anuradha kUMARI Wusirika ramakrishna Department of Biochemistry Central University of PunjabPunjab 151401India

Tissue culture techniques were used to produce large amounts of bioactive compounds with medicinal potential, overcoming space and time constraints for cancer prevention. Rice callus suspension cultures(RCSC) and seed extracts prepared from aromatic rice varieties were used to evaluate the cytotoxic impact on human colon and lung cancer cell lines, as well as a normal control cell line, using Taxol as a positive control. RCSC and seed extracts from two Indian aromatic rice varieties were applied at different concentrations to treat the cancer cell lines and normal lung fibroblasts over varying time intervals. Apoptosis was assessed in 1:5 dilutions of the A549 and HT-29 cell lines treated with RCSC for 72 h, using propidium iodide staining and flow cytometry. RCSC showed a more potent cytotoxic effect than seed extracts with minimal effect on the normal cell line, in contrast to Taxol. Confocal microscopy and flow cytometry further confirmed the apoptotic effect of RCSC. Gas chromatography-mass spectrometry-based metabolic profiling identified metabolites involved in cytotoxicity and highlighted altered pathways. RCSC is proposed as an alternative source for the development of novel anticancer drugs with reduced side effects.

关键词： anticancer cytotoxicity metabolite profiling plant tissue culture rice callus suspension culture secondary metabolite

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Synthesis of novel isoxazolyl bis-thiazolo[3,2-a]pyrimidines

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Chinese Chemical Letters 2012年第8期23卷 899-902页

作者： E.Rajanarendar S.ramakrishna k.Rama Murthy Department of Chemistry Kakatiya UniversityWarangalAP 506 009India

A new synthetic strategy for the synthesis of novel 3-（3-（3-methyl-4-nitroisoxazol-5-yl）-2-phenyl-1-（5,7-diaryl-7H-thia- zolo[3,2-a]pyrimidin-3-yl）propyl）-5,7-diaryl-7H-thiazolo[3,2-a]pyrimidines （7a-i） analogues is described. Reaction of 3-（2- （3-methyl-4-nitroisoxazole-5-yl）-l-phenylethyl）pentane-2,4-dione （3） with two moles of thiourea in presence of iodine and CuO afforded 4-（1-（2-aminothiazol-4-yl）-3-（3-methyl-4-nitroisoxazol-5-yl）-2-aryl propylthiazol-2-amine （5）. Compound 5 on reaction with two moles of chalcone （6） furnished novel 3-（3-（3-methyl-4-nitroisoxazol-5-yl）-2-phenyl-1-（5,7-diaryl-7H-thiazolo[3,2- a]pyrimidin-3-yl）propyl）-5,7-diaryl-7H-thiazolo[3,2-a ]pyrimidines （Ta-i）.

关键词： Isoxazolyl bis-thiazoles Isoxazolyl bis-thiazolo[3,2-a]pyrimidines New synthetic strategy

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Dynamic Responses of Atmospheric Carbon Dioxide Concentration to Global Temperature Changes between 1850 and 2010

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Advances in Atmospheric Sciences 2016年第2期33卷 247-258页

作者： Weile WANG ramakrishna NEMANI Department of Science and Environmental Policy California State University at Monterey Bay Earth Science Division NASA Ames Research Center NASA Advanced Supercomputing Division NASA Ames Research Center

Changes in Earth＇s temperature have significant impacts on the global carbon cycle that vary at different time scales, yet to quantify such impacts with a simple scheme is traditionally deemed difficult. Here, we show that, by incorporating a tem- perature sensitivity parameter （1.64 ppm yr-1 ℃-1） into a simple linear carbon-cycle model, we can accurately characterize the dynamic responses of atmospheric carbon dioxide （CO2） concentration to anthropogenic carbon emissions and global temperature changes between 1850 and 2010 （r2 〉 0.96 and the root-mean-square error 〈 1 ppm for the period from 1960 onward）. Analytical analysis also indicates that the multiplication of the parameter with the response time of the atmospheric carbon reservoir （-12 year） approximates the long-term temperature sensitivity of global atmospheric CO2 concentration （-15 ppm ℃ 1）, generally consistent with previous estimates based on reconstructed CO2 and climate records over the Little Ice Age. Our results suggest that recent increases in global surface temperatures, which accelerate the release of carbon from the surface reservoirs into the atmosphere, have partially offset surface carbon uptakes enhanced by the elevated atmo- spheric CO2 concentration and slowed the net rate of atmospheric CO2 sequestration by global land and oceans by -30% since the 1960s. The linear modeling framework outlined in this paper thus provides a useful tool to diagnose the observed atmospheric CO2 dynamics and monitor their future changes.

关键词： atmospheric CO2 dynamics climate-carbon interactions climate change carbon cycle

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A facile and convenient synthesis of novel imidazo[1,2-b] isoxazoles and their Mannich bases as potential biodynamic agents

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Chinese Chemical Letters 2015年第12期26卷 1511-1513页

作者： E.Rajanarendar k.Thirupathaiah S.ramakrishna D.Nagaraju Department of Chemistry Kakatiya University

A series of novel imidazo[1,2-b]isoxazoles 3 and their Mannich bases 4–6 were synthesized via convenient reactions. The reaction of 3-aminoisoxazole 1 with substituted phenacyl bromides 2 in dry ethanol afforded the corresponding 6-methyl-3-aryl imidazo[1,2-b]isoxazoles 3 in good *** 3 on treatment with 37% formaline and secondary amines furnished the corresponding novel Mannich bases viz., 6-methyl-3-aryl-2-（morpholine/pyrrolidin-1-yl/piperidin-1-yl）-methyl-imidazo[1,2-b]isoxazoles 4–6.

关键词： convenient facile bases substituted amines antibacterial acetic chloroform ethanol pyrrolidine

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Enhancing Power Line Insulator Health Monitoring with a Hybrid Generative Adversarial Network and YOLO3 Solution

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TSINGHUA SCIENCE AND TECHNOLOGY 2024年第6期29卷 1796-1809页

作者： Akella, ramakrishna Gunturi, Sravan kumar Sarkar, Dipu koneru Lakshmaiah Educ Fdn Dept Elect & Commun Engn Hyderabad 500075 India Natl Inst Technol Nagaland Dept Elect & Elect Engn Dimapur 797103 India

In the critical field of electrical grid maintenance, ensuring the integrity of power line insulators is a primary concern. This study introduces an innovative approach for monitoring the condition of insulators using aerial surveillance via drone-mounted cameras. The proposed method is a composite deep learning framework that integrates the "You Only Look Once" version 3 (YOLO3) model with deep convolutional generative adversarial networks (DCGAN) and super-resolution generative adversarial networks (SRGAN). The YOLO3 model excels in rapidly and accurately detecting insulators, a vital step in assessing their health. Its effectiveness in distinguishing insulators against complex backgrounds enables prompt detection of defects, essential for proactive maintenance. This rapid detection is enhanced by DCGAN's precise classification and SRGAN's image quality improvement, addressing challenges posed by low-resolution drone imagery. The framework's performance was evaluated using metrics such as sensitivity, specificity, accuracy, localization accuracy, damage sensitivity, and false alarm rate. Results show that the SRGAN+DCGAN+YOLO3 model significantly outperforms existing methods, with a sensitivity of 98%, specificity of 94%, an overall accuracy of 95.6%, localization accuracy of 90%, damage sensitivity of 92%, and a reduced false alarm rate of 8%. This advanced hybrid approach not only improves the detection and classification of insulator conditions but also contributes substantially to the maintenance and health of power line insulators, thus ensuring the reliability of the electrical power grid.

关键词： Training Location awareness Deep learning Accuracy Sensitivity Surveillance Insulators DCGAN generative adversarial networks insulators SRGAN YOLO

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Recent Advances in Metal–Organic Frameworks Based on Electrospinning for Energy Storage

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Advanced Fiber Materials 2023年第5期5卷 1592-1617页

作者： Shunyu Yao Seeram ramakrishna Gang Chen MIIT key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001People’s Republic of China Center for Nanotechnology and Sustainability Department of Mechanical EngineeringNational University of SingaporeSingapore 119260Singapore

Metal–organic frameworks are linked by different central organic ligands and metal-ion coordination bonds to form periodic pore structures and rich pore *** of their structural advantages,metal–organic frameworks are considered to be one of the most promising candidates for new energy storage *** better utilize their advantages,metal–organic frameworks can be combined with electrospinning technology to effectively adjust the porosity and mechanical strength of composite *** paper summarizes the combination of the latest metal–organic frameworks and classical spinning technology,starting from the structural design of electrode materials,and applying them to supercapacitors,lithium-ion batteries,lithium–sulfur batteries,sodium-ion batteries,and potassium-ion ***,the problems and challenges related to the preparation of metal–organic framework nanofibers are summarized,and future development trends are predicted.

关键词： Metal-organic frameworks(MOFs) Supercapacitors Electrospinning Lithium-ion batteries Sodium-ion batteries

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