222 research outputs found
A Study of nature of the Photovoltaic modules under the influence of partial shading effect
The behaviour of the solar photovoltaic array will be rapidly changing under the influence of partial shading phenomenon. When two (or) more photovoltaic modules are embedded in series, then the total output voltage and the net output power obtained from the series connected photovoltaic modules will mainly depends upon the solar insolation which is being projected upon each and every module respectively. Small perturbation in solar irradiation levels will lead to large considerable change in the output parameters. This paper mainly focuses on observing the effect of partial shading on photovoltaic modules which are connected in series. The main objective of this paper is to examine about the mismatching phenomenon that occurs while tracking the global maxima point which plays a vital role in extracting maximum power from solar photovoltaic array in an effective manner
The Black Swan â Knowing the Unknown in Projects
A âBlack Swanâ is produced when the gap between what we know and what we think we know becomes dangerously wide (Taleb, 2007). This concept is closely related to uncertainty and learning. A Black Swan event is usually a surprise, at least to the observer. However the Black Swan event very much depends on the observer. What may be a Black Swan surprise for a turkey is not a Black Swan surprise to its butcher; so the main objective is to âavoid being the turkeyâ by exploring and identifying areas of vulnerability in order to avoid surprises. In projects, while some may disagree, almost all failures, even catastrophic ones, are not really Black Swan events but a series of failures that alone may have a negative impact on project outcomes but combined lead to catastrophic failure. However it is surprising how often experienced project teams ignore the early warning signs and move forward into the project lifecycle despite serious problems in many areas that are keys to project success. This will ultimately lead to the Black Swan event materializing. That is when it is too late to take any preventive actions. This paper will characterize the Black Swan concept in projects and describe its nature and identify organizational mechanisms that can be useful in dealing with Black Swan surprises in projects. This study is mainly based on literature study, however carries out an assessment on examples of Black Swan events in order to better clarify the concept under study
Variations in Litterfall Dynamics, C:N:P Stoichiometry and Associated Nutrient Return in Pure and Mixed Stands of Camphor Tree and Masson Pine Forests
Litterfall, directly and indirectly, affects the soil physicochemical properties, microbial activity, and diversity of soil fauna and flora by adding organic matter and nutrients to the soil. This study explores litterfall dynamics such as litterfall production, litter decomposition rate, and associated nutrient return in three forest types, that is, camphor tree forest (CTF), Masson pine forest (MPF), and camphor tree and Masson pine mixed forest (CMF), in subtropical China. Results showed that CMF had the highest mean annual litterfall production (4.30 ± 0.22 t haâ1), which was significantly higher than that of MPF (3.41 ± 0.25 t haâ1) and CTF (3.26 ± 0.17 t haâ1). Leaf represented the major fraction of litterfall, constituting over 71% of the total litterfall mass in the three forest types. The contribution of branch litter was 16.3, 8.9, and 16.9%, and miscellaneous litter was 12.6, 18.9, and 11.1% in CTF, MPF, and CMF, respectively. The concentration of macronutrients ranked as N > Ca > K > Mg > P in all litter fractions. The total annual macronutrient return to the soil from the litterfall was in order as CTF (74.2 kg haâ1â§yrâ1) > CMF (70.7 kg haâ1â§yrâ1) > MPF (33.6 kg haâ1â§yrâ1). The decomposition rate was higher in leaf litter than in branch litter throughout the three forests. Among the forest types, the leaf and branch decomposition rates were in a pattern: CTF > CMF > MPF. The ratio of C/N in both leaf and branch litters was significantly higher in MPF than in CTF and CMF, while no significant differences in N/P ratio were found in these litters among the three forests. The high N:P ratios in leaf litter (23/30) and the branch (24/32) litter indicated the high N returning and low nutrient returning to the soil. Our results suggested that the broadleaved forests have faster litter decomposition and higher macronutrient returns than conifer forests. Moreover, the litter decomposition rate was mainly associated with litterfall quality and chemical composition. The introduction of broadleaved trees into monoculture coniferous stands could increase litter production nutrients return, and thus, it had advantages in soil nutrients restoration and sustainable forest management
Evaluation of antiarthritic activity of Strychnos potatorum Linn seeds in Freund's adjuvant induced arthritic rat model
<p>Abstract</p> <p>Background</p> <p><it>Strychnos potatorum </it>Linn (Loganiaceae) is a moderate sized tree found in southern and central parts of India, Sri Lanka and Burma. In traditional system of medicine, <it>Strychnos potatorum </it>Linn seeds were used for various ailments including inflammation, diabetes etc. To investigate the folkloric use of the seeds the present study was carried out on Freund's adjuvant induced arthritic rats.</p> <p>Methods</p> <p>The present study states the effect of the aqueous extract (SPE) and the whole seed powder (SPP) of <it>Strychnos potatorum </it>Linn seeds on the Freund's complete adjuvant (FCA) induced arthritic rat paw edema, body weight changes and alterations in haematological and biochemical parameters in both developing and developed phases of arthritis. Histopathology of proximal interphalangeal joints and radiology of hind legs were studied.</p> <p>Results</p> <p>In FCA induced arthritic rats, there was significant increase in rat paw volume and decrease in body weight increment, whereas SPP and SPE treated groups, showed significant reduction in paw volume and normal gain in body weight. The altered haematological parameters (Hb, RBC, WBC and ESR) and biochemical parameters (blood urea, serum creatinine, total proteins and acute phase proteins) in the arthritic rats were significantly brought back to near normal by the SPP and SPE treatment at the dose of 200 mg/kg/p.o in both developing and developed phases of arthritis. Further the histopathological and radiological studies revealed the antiarthritic activity of SPP and SPE by indicating fewer abnormalities in these groups when compared to the arthritic control group.</p> <p>Conclusion</p> <p>In conclusion, both SPP and SPE at the specified dose level of 200 mg/kg, p.o. showed reduction in rat paw edema volume and it could significantly normalize the haematological and biochemical abnormalities in adjuvant induced arthritic rats in both developing and developed phases of FCA induced arthritis. Further the histopathological and radiological studies confirmed the antiarthritic activity of SPP and SPE.</p
Synthesis and down conversion emission property of Eu3+ doped LaAlO3 CsAlO2 and LiLaO2 phosphors
[EN] LaAlO3:Eu3+, CsAlO2:Eu3+ and LiLaO2:Eu3+ phosphors with varying concen- trations of Eu3+ from 3 to 10 mol% were prepared by combustion synthesis method and the samples were further heated to 1,000ÂșC to improve the crystallinity of the materials. The structure and morphology of materials have been examined by X-ray diffraction and scan- ning electron microscopy. SEM images depicted that the morphology of crystallites have no uniform shapes and sizes. Small and coagulated particles of irregular shapes of different sizes are obtained. The characteristic emissions of Eu3+ were clearly observed at nearly 580, 592, 650, 682 to 709 (multiplet structure) nm for 5D - 7 Fn transitions where n = 0, 1, 3, 4 respectively, including the strongest emission peaks at 614 and 620 nm for 5 D0 - 7 F2 transitions in CsAlO2:Eu3+ and LiLaO2:Eu3+ host lattices. The intensity of emission peak corresponding to 5 D0 !→ 7 F1 transitions in LaAlO3 :Eu3+ material is comparable to that of 5D0 5D-7F2 transitions which is also a singlet. Photoluminescence intensity follows the order as in LiLaO2 > LaAlO3 > CsAlO2 lattices. Remarkable high photoluminescence intensity with 7 mol% doping of Eu3+ in LiLaO2 makes it a strong contender for red colored display applications.This work was supported by the European Commission through Nano CIS project (FP7-PEOPLE-2010-IRSES ref. 269279).MarĂ Soucase, B.; Singh, KC.; Moya Forero, MM.; Singh, I.; Om, H.; Chand, S. (2015). Synthesis and down conversion emission property of Eu3+ doped LaAlO3 CsAlO2 and LiLaO2 phosphors. Optical and Quantum Electronics. 47(7):1569-1578. https://doi.org/10.1007/s11082-014-9997-9S15691578477Abbattista, F., Vallino, M.: Remarks on the La 2 O 3 - Li 2 O binary system between 750 and 1,000Â â C. Ceram. Int. 9, 35â38 (1983)Bae, Y., Lee, K., Byeon, S.: Synthesis and Eu 3 + concentration-dependent photoluminescence of Gd 2 - x Eu x O 3 nanowires. J. Lumin. 129, 81â85 (2009)Blasse, G., Grambier, B.: Luminescent Materials, vol. 43. Springer, Berlin, pp. 43â46 (1994)DereĆ, P., Krupa, J.: Spectroscopic investigations of LaAlO 3 : Eu 3 + . J. Lumin. 102â103, 386â390 (2003)Ekambaram, S., Patil, K.: Synthesis and properties of Eu 2 + activated blue phosphors. J. Alloys Compd. 248, 7â12 (1997)Gao, X., Lei, L., Lv, C., Sun, Y., Zheng, H., Cui, Y.: Preparation and photoluminescence property of a loose powder, Ca 3 Al 2 O 6 : Eu 3 + by calcination of a layered double hydroxide precursor. J. Solid State Chem. 181, 1776â1781 (2008)Hayakawa, T., Kamt, N., Yamada, K.: Visible emission characteristics in Tb 3 + -doped fluorescent glasses under selective excitation. J. Lumin. 68, 179â186 (1996)Hreniak, D., Strek, W., DereĆ, P., Bednarkiewicz, A., Ćukowiak, A.: J. Alloys Compd. 408, 828â830 (2006)Huang, Y., Jiang, C., Cao, Y., Shi, L., Seo, H.: Luminescence and microstructures of Eu 3 + -doped in triple phosphate Ca 8 MgR ( PO 4 ) 7 (R = La, Gd, Y) with whitlockite structure. Mater. Res. Bull. 44, 793â798 (2009)Kharbache, H., Mahiou, R., Boutinaud, P., Boyer, D., Zakaria, D., Deren, P.: Experimental evidence of Eu 3 + pairs in K 2 EuF 5 . Opt. Mater. 31, 558â561 (2009)Kijima, T., Shinbori, T., Sekita, M., Uota, M., Sakai, G.: Abnormally enhanced Eu 3 + emission in Y 2 O 2 SO 4 : Eu 3 + inherited from their precursory dodecylsulfate-templated concentric-layered nanostructure. J. Lumin. 128, 311â316 (2008)Liu, G., Hong, G., Wang, J., Dong, X.: Hydrothermal synthesis of spherical and hollow Gd 2 O 3 : Eu 3 + phosphors. J. Alloys Compd. 432, 200â204 (2007)MÄ
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In vitro anti-HIV activity of some Indian medicinal plant extracts
Background
Human Immunodeficiency Virus (HIV) persists to be a significant public health issue worldwide. The current strategy for the treatment of HIV infection, Highly Active Antiretroviral Therapy (HAART), has reduced deaths from AIDS related disease, but it can be an expensive regime for the underdeveloped and developing countries where the supply of drugs is scarce and often not well tolerated, especially in persons undergoing long term treatment. The present therapy also has limitations of development of multidrug resistance, thus there is a need for the discovery of novel anti-HIV compounds from plants as a potential alternative in combating HIV disease.
Methods
Ten Indian medicinal plants were tested for entry and replication inhibition against laboratory adapted strains HIV-1IIIB, HIV-1Ada5 and primary isolates HIV-1UG070, HIV-1VB59 in TZM-bl cell lines and primary isolates HIV-1UG070, HIV-1VB59 in PM1 cell lines. The plant extracts were further evaluated for toxicity in HEC-1A epithelial cell lines by transwell epithelial model.
Results
The methanolic extracts of Achyranthes aspera, Rosa centifolia and aqueous extract of Ficus benghalensis inhibited laboratory adapted HIV-1 strains (IC80 3.6â118âÎŒg/ml) and primary isolates (IC80 4.8â156âÎŒg/ml) in TZM-bl cells. Methanolic extract of Strychnos potatorum, aqueous extract of Ficus infectoria and hydroalcoholic extract of Annona squamosa inhibited laboratory adapted HIV-1 strains (IC80 4.24â125âÎŒg/ml) and primary isolates (IC80 18â156âÎŒg/ml) in TZM-bl cells. Methanolic extracts of Achyranthes aspera and Rosa centifolia, (IC801-9âÎŒg/ml) further significantly inhibited HIV-1 primary isolates in PM1cells. Methanolic extracts of Tridax procumbens, Mallotus philippinensis, Annona reticulate, aqueous extract of Ficus benghalensis and hydroalcoholic extract of Albizzia lebbeck did not exhibit anti-HIV activity in all the tested strains. Methanolic extract of Rosa centifolia also demonstrated to be non-toxic to HEC-1A epithelial cells and maintained epithelial integrity (at 500âÎŒg/ml) when tested in transwell dual-chamber.
Conclusion
These active methanolic extracts of Achyranthes aspera and Rosa centifolia, could be further subjected to chemical analysis to investigate the active moiety responsible for the anti-HIV activity. Methanolic extract of Rosa centifolia was found to be well tolerated maintaining the epithelial integrity of HEC-1A cells in vitro and thus has potential for investigating it further as candidate microbicide
Emodin Suppresses Migration and Invasion through the Modulation of CXCR4 Expression in an Orthotopic Model of Human Hepatocellular Carcinoma
10.1371/journal.pone.0057015PLoS ONE83
Civil society leadership in the struggle for AIDS treatment in South Africa and Uganda
Includes abstract.Includes bibliographical references.This thesis is an attempt to theorise and operationalise empirically the notion of âcivil society leadershipâ in Sub-Saharan Africa. âAIDS leadership,â which is associated with the intergovernmental institutions charged with coordinating the global response to HIV/AIDS, is both under-theorised and highly context-specific. In this study I therefore opt for an inclusive framework that draws on a range of approaches, including the literature on âleadershipâ, institutions, social movements and the ânetworkâ perspective on civil society mobilisation. This framework is employed in rich and detailed empirical descriptions (âthick descriptionâ) of civil society mobilisation around AIDS, including contentious AIDS activism, in the key case studies of South Africa and Uganda. South Africa and Uganda are widely considered key examples of poor and good leadership (from national political leaders) respectively, while the Treatment Action Campaign (TAC) and The AIDS Support Organisation (TASO) are both seen as highly effective civil society movements. These descriptions emphasise âtransnational networks of influenceâ in which civil society leaders participated (and at times actively constructed) in order to mobilise both symbolic and material resources aimed at exerting influence at the transnational, national and local levels
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