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      • SCOPUS

        Effect of zinc insertion and hydrophobicity on the membrane interactions and PDT activity of porphyrin photosensitizers

        Pavani, Christiane,Uchoa, Adjaci F.,Oliveira, Carla S.,Iamamoto, Yassuko,Baptista, Mauricio S. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.2

        A series of photosensitizers (PS), which are meso-substituted tetra-cationic porphyrins, was synthesized in order to study the role of amphiphilicity and zinc insertion in photodynamic therapy (PDT) efficacy. Several properties of the PS were evaluated and compared within the series including photophysical properties (absorption spectra, fluorescence quantum yield $\Phi_f$, and singlet oxygen quantum yield $\Phi_{\Delta}$), uptake by vesicles, mitochondria and HeLa cells, dark and phototoxicity in HeLa cells. The photophysical properties of all compounds are quite similar ($\Phi_f\;{\leq}\;0.02$; $\Phi_{\Delta}\;{\sim}\;0.8$). An increase in lipophilicity and the presence of zinc in the porphyrin ring result in higher vesicle and cell uptake. Binding in mitochondria is dependent on the PS lipophilicity and on the electrochemical membrane potential, i.e., in uncoupled mitochondria PS binding decreases by up to 53%. The porphyrin substituted with octyl groups (TC8PyP) is the compound that is most enriched in mitochondria, and its zinc derivative (ZnTC8PyP) has the highest global uptake. The stronger membrane interaction of the zinc-substituted porphyrins is attributed to a complexing effect with phosphate groups of the phospholipids. Zinc insertion was also shown to decrease the interaction with isolated mitochondria and with the mitochondria of HeLa cells, an effect that has been explained by the particular characteristics of the mitochondrial internal membrane. Phototoxicity was shown to increase proportionally with membrane binding efficiency, which is attributed to favorable membrane interactions which allow more efficient membrane photooxidation. For this series of compounds, photodynamic efficiency is directly proportional to the membrane binding and cell uptake, but it is not totally related to mitochondrial targeting.

      • SCIESCOPUSKCI등재

        Reproductive Performance of Holstein Dairy Cows Grazing in Dry-summer Subtropical Climatic Conditions: Effect of Heat Stress and Heat Shock on Meiotic Competence and In vitro Fertilization

        Pavani, Krishna,Carvalhais, Isabel,Faheem, Marwa,Chaveiro, Antonio,Reis, Francisco Vieira,da Silva, Fernando Moreira Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.3

        The present study was designed to evaluate how environmental factors in a dry-summer subtropical climate in Terceira-Azores (situated in the North Atlantic Ocean: $38^{\circ}43^{\prime}N27^{\circ}12^{\prime}W$) can affect dairy cow (Holstein) fertility, as well as seasonal influence on in vitro oocytes maturation and embryos development. Impact of heat shock (HS) effects on in vitro oocyte's maturation and further embryo development after in vitro fertilization (IVF) was also evaluated. For such purpose the result of the first artificial insemination (AI) performed 60 to 90 days after calving of 6,300 cows were recorded for one year. In parallel, climatic data was obtained at different elevation points (n = 5) from 0 to 1,000 m and grazing points from 0 to 500 m, in Terceira island, and the temperature humidity index (THI) was calculated. For in vitro experiments, oocytes (n = 706) were collected weekly during all year, for meiotic maturation and IVF. Further, to evaluate HS effect, 891 oocytes were collected in the cold moths (December, January, February and March) and divided in three groups treated to HS for 24 h during in vitro maturation at: C (Control = $38.5^{\circ}C$), HS1 ($39.5^{\circ}C$) and HS2 ($40.5^{\circ}C$). Oocytes from each group were used for meiotic assessment and IVF. Cleavage, morula and blastocyst development were evaluated respectively on day 2, 6, and 9 after IVF. A negative correlation between cow's conception rate (CR) and THI in grazing points (-91.3%; p<0.001) was observed. Mean THI in warmer months (June, July, August and September) was $71.7{\pm}0.7$ and the CR ($40.2{\pm}1.5%$) while in cold months THI was $62.8{\pm}0.2$ and CR was $63.8{\pm}0.4%$. A similar impact was obtained with in vitro results in which nuclear maturation rate (NMR) ranged from 78.4% (${\pm}8.0$) to 44.3% (${\pm}8.1$), while embryos development ranged from 53.8% (${\pm}5.8$) to 36.3% (${\pm}3.3$) in cold and warmer months respectively. In vitro HS results showed a significant decline (p<0.05) on NMR of oocytes for every $1^{\circ}C$ rising temperature ($78.4{\pm}8.0$, $21.7{\pm}3.1$ and $8.9{\pm}2.2$, respectively for C, HS1, and HS2). Similar results were observed in cleavage rate and embryo development, showing a clear correlation (96.9 p<0.05) between NMR and embryo development with respect to temperatures. Results clearly demonstrated that, up to a THI of 70.6, a decrease in the CR occurs in first AI after calving; this impairment was confirmed with in vitro results.

      • KCI등재

        Reproductive Performance of Holstein Dairy Cows Grazing in Dry-summer Subtropical Climatic Conditions: Effect of Heat Stress and Heat Shock on Meiotic Competence and In vitro Fertilization

        Krishna Pavani,Isabel Carvalhais,Marwa Faheem,Antonio Chaveiro,Francisco Vieira Reis,Fernando Moreira da Silva 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.3

        The present study was designed to evaluate how environmental factors in a dry-summer subtropical climate in Terceira-Azores (situated in the North Atlantic Ocean: 38° 43' N 27° 12' W) can affect dairy cow (Holstein) fertility, as well as seasonal influence on in vitro oocytes maturation and embryos development. Impact of heat shock (HS) effects on in vitro oocyte’s maturation and further embryo development after in vitro fertilization (IVF) was also evaluated. For such purpose the result of the first artificial insemination (AI) performed 60 to 90 days after calving of 6,300 cows were recorded for one year. In parallel, climatic data was obtained at different elevation points (n = 5) from 0 to 1,000 m and grazing points from 0 to 500 m, in Terceira island, and the temperature humidity index (THI) was calculated. For in vitro experiments, oocytes (n = 706) were collected weekly during all year, for meiotic maturation and IVF. Further, to evaluate HS effect, 891 oocytes were collected in the cold moths (December, January, February and March) and divided in three groups treated to HS for 24 h during in vitro maturation at: C (Control = 38.5°C), HS1 (39.5°C) and HS2 (40.5°C). Oocytes from each group were used for meiotic assessment and IVF. Cleavage, morula and blastocyst development were evaluated respectively on day 2, 6, and 9 after IVF. A negative correlation between cow’s conception rate (CR) and THI in grazing points (–91.3%; p<0.001) was observed. Mean THI in warmer months (June, July, August and September) was 71.7±0.7 and the CR (40.2±1.5%) while in cold months THI was 62.8±0.2 and CR was 63.8±0.4%. A similar impact was obtained with in vitro results in which nuclear maturation rate (NMR) ranged from 78.4% (±8.0) to 44.3% (±8.1), while embryos development ranged from 53.8% (±5.8) to 36.3% (±3.3) in cold and warmer months respectively. In vitro HS results showed a significant decline (p<0.05) on NMR of oocytes for every 1°C rising temperature (78.4±8.0, 21.7±3.1 and 8.9±2.2, respectively for C, HS1, and HS2). Similar results were observed in cleavage rate and embryo development, showing a clear correlation (96.9 p<0.05) between NMR and embryo development with respect to temperatures. Results clearly demonstrated that, up to a THI of 70.6, a decrease in the CR occurs in first AI after calving; this impairment was confirmed with in vitro results.

      • SCIESCOPUS

        Analysis of active cooling panels in a scramjet combustor considering the thermal cracking of hydrocarbon fuel

        Sreekireddy, Pavani,Reddy, Tadisina Kishen Kumar,Selvaraj, Prabhu,Reddy, Vanteru Mahendra,Lee, Bok Jik Elsevier 2019 Applied thermal engineering Vol.147 No.-

        <P><B>Abstract</B></P> <P>In this paper, a procedure is demonstrated for the numerical analysis of a cooling system using active panels for high-speed combustion chambers subjected to high thermo-mechanical loads. A promising alloy for high heat loads, namely, niobium Cb-752, is considered in this study. In addition to sensible heat transfer, endothermic heat absorption through the cracked hydrocarbon fuels is a viable option for cooling the chamber panels. The focus of the panel design is to minimize the weight with the safe thermo-mechanical characteristics of the panel. The present analysis is carried out in three steps. First, a one-dimensional (1D) analytical model is developed. The second and third steps are three-dimensional (3D) analyses without and with consideration of fuel endothermicity, respectively. The optimal channel dimensions obtained from the 1D analysis provide inputs for the 3D analysis. The channel dimensions obtained from the 1D analysis do not satisfy the targeted parameters in the 3D analysis. Thus, the channel is redesigned in 3D and tested with and without cracking. The channel dimensions are optimized for the ranges of heat fluxes (160–220 W/cm<SUP>2</SUP>) in the combustor and mass flow rates (0.011–0.015 kg/s) of the fuel in the channel. Reducing the weight of the panel is sought by considering the benefit of heat absorption through the endothermic cracking process in the fuel channel. The combination of an increased width and cracking performs better than the other non-cracking cases. The study presents the most efficient configuration suitable for applications in high-speed combustion chambers under the given heat flux conditions. By increasing the channel width and cracking (for 3D), the weight of the panel is reduced by 10.58%. The fuel exit temperature, fuel cracking behavior in the channel, structural stress distribution and weight of the panel are analyzed in terms of the operating conditions.</P>

      • KCI등재

        Performance evaluation and optimization of nano boric acid powder weight percentage mixed with vegetable oil using the Taguchi approach

        P. N. L. Pavani,R. Pola Rao,S. Srikiran 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

        Turning, which is a widely employed method of metal removal process in manufacturing industries, generates many temperatures becauseof the increase in cutting forces. In view of the high temperatures developed in the process, tools deteriorate, and so good surfacequality is difficult to achieve. Lubrication becomes critical to minimize the forces and temperatures generated during the process. In thepresent work, boric acid powder is used as a solid lubricant, which is mixed with vegetable oils such as coconut oil and soybean oil inturning process. The results indicate that there is a considerable improvement in the machining performance with boric acid assistedMQL in machining compared with dry and wet machining. Taguchi method is a powerful problem solving technique for improving processperformance, yield, and productivity. Combining the speed, feed, and depth of cut is helpful. In the present study, the combinationusing Taguchi DOE was taken as factors, levels, and 32 experimental layouts are framed. The current study attempts to study the variationsin tool temperature; cutting forces and surface roughness of the machined component under various machining conditions to findthe optimum weight percentage of the solid lubricant used.

      • Design and stress analysis of femur bone implant with composite plates

        Ramakrishna, S.,Pavani, B. Techno-Press 2020 Biomaterials and Biomechanics in Bioengineering Vol.5 No.1

        Development of lightweight implant plates are important to reduce the stress shielding effect for a prosthesis of femur bone fractures. Stainless steel (SS-316L) is a widely used material for making implants. Stress shielding effect and other issues arise due to the difference in mechanical properties of stainless steel when compared with bone. To overcome these issues, composite materials seem to be a better alternative solution. The comparison is made between two biocompatible composite materials, namely Ti-hydroxyapatite and Ti-polypropylene. "Titanium (Ti)" is fiber material while "hydroxyapatite" and "polypropylene" are matrix materials. These two composites have Young's modulus closer to the bone than stainless steel. Besides the variety of bones, present paper constrained to femur bone analysis only. Being heaviest and longest, the femur is the most likely to fail among all bone failures in human. Modelling of the femur bone, screws, implant and assembly was carried out using CATIA and static analysis was carried out using ANSYS. The femur bone assembly was analyzed for forces during daily activities. Ti-hydroxyapatite and Ti-polypropylene composite implants induced more stress in composite implant plate, results less stress induced in bone leading to a reduction in shielding effect than stainless steel implant plate thus ensuring safety and quick healing for the patient.

      • KCI등재

        CO2 fixation and lipid production by microalgal species

        Srinivasa Reddy Ronda,Pavani Parupudi,Chandrika Kethineni,Pradip Babanrao Dhamole,Sandeep Vemula,Prasada Rao Allu,Mahendran Botlagunta,Sujana Kokilagadda 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.2

        Microalgal species Nannochloropsis limnetica, Botryococcus braunii, and Stichococcus bacillaris were compared for their ability to grow, remove CO2, and accumulate lipids in their biomass under CO2-enriched atmosphere. Overall, N. limnetica outperformed the other two cultures and distinctly exhibited higher specific growth rate (0.999 d−1) and CO2 fixation rate (0.129 gL−1 d−1) with a high specific lipid yield (40% w/w). The volumetric CO2 fixation rate for all three species was validated with biomass productivity and mass transfer methods (P<0.005 and R2=0. 98). At 10% CO2, N. limnetica showed one-and-a-half times more carbon fixation efficiency over B. braunii, and S. bacillaris. On the other hand, total fatty acids of N. limnetica dispalyed an apparent increase in oleic acid. Whereas, under similar conditions, N. limnetica exhibited reduced eicosapentaenoic acid. These findings suggest that at high CO2 conditions, N. limnetica proved to be an efficient CO2 capture algal system and can be considered for biofuel applications.

      • KCI등재

        Optimization of medium components using orthogonal arrays for γ-Linolenic acid production by Spirulina platensis

        Srinivasa Reddy Ronda,Pavani Lakhsmi Chandrika Parupudi,Sandeep Vemula,Santhosh Tumma,Mahendran Botlagunta,Vijaya Saradhi Settaluri,Smita Lele,Suraj Sharma,Chari Kandala 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.10

        This work describes the medium optimization of γ-Linolenic acid (GLA) production by Spirulina platensisusing one-factor and orthogonal array design methods. In the one-factor experiments, NaHCO3 (9 mg L−1), NaNO3(13.5 mg L−1) and MgSO4·7H2O (11.85 mg L−1) proved to be the best components for GLA production. The optimalpH for GLA production by the alga was 9.2. Based on the delta values, NaHCO3 showed the greatest effect on the GLAproduction of the various factors tested, followed in decreasing order by MgSO4·7H2O, NaNO3 and K2SO4. The max-imum GLA yield obtained was 19.2 mgL−1in the presence of optimum concentrations of NaHCO3 (20 g L−1), NaNO3(3 g L−1), MgSO4·7H2O (0.5 g L−1) and K2SO4 (1.5 g L−1). Because of the slow growth rate of the algae, the practiceof robust orthogonal array methods during the optimization of medium components can result in the production of anoptimal biomass and a higher GLA yield for nutraceutical applications.

      • KCI등재

        α-lipoic acid protects testis and epididymis against linuron-induced oxidative toxicity in adult rats

        Prathima P.,Venkaiah K.,Daveedu T.,Pavani R.,Sukeerthi S.,Gopinath M.,Sainath Sri Bhashaym 한국독성학회 2020 Toxicological Research Vol.36 No.4

        Linuron is well known for its antiandrogenic property. However, the effects of linuron on testicular and epididymal pro- and antioxidant status are not well defined. On the other hand, α-lipoic acid is well known as universal antioxidant. Therefore, the purpose of this study was twofold: firstly to investigate whether linuron exposure alters antioxidant status in the testis and epididymis of rats and if so, whether the supplementation of α-lipoic acid mitigates linuron-induced oxidative toxicity in rats. To address this question, α-lipoic acid at a dose of 70 mg/Kg body weight (three times a week) was administered to linuron exposed rats (10 or 50 mg/Kg body weight, every alternate day over a period of 60 days), and the selected reproductive endpoints were analyzed after 60 days. Respective controls were maintained in parallel. Linuron at selected doses reduced testicular daily sperm count, and epididymal sperm count, sperm motility, sperm viability, and number of tail coiled sperm, reduced activity levels of 3β- and 17β-hydroxysteroid dehydrogenases, decreased expression levels of StAR mRNA, inhibition of testosterone levels, and elevated levels of testicular cholesterol in rats over controls. Linuron intoxication deteriorated the structural integrity of testis and epididymis associated with reduced the reproductive performance over controls. Conversely, α-lipoic acid supplementation enhanced sperm quality and improved the testosterone synthesis pathway in linuron exposed rats over its respective control. Administration of α-lipoic acid restored inhibition of testicular and epididymal enzymatic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidise) and non-enzymatic (glutathione content), increased lipid peroxidation and protein carbonyl content produced by linuron in rats. α-lipoic acid supplementation inhibited the expression levels of testicular caspase-3 mRNA levels and also its activity in linuron treated rats. To summate, α-lipoic acid-induced protection of reproductive health in linuron treated rats could be attributed to its antioxidant, and steroidogenic properties.

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