288 research outputs found
Particle motion around charged black holes in generalized dilaton-axion gravity
No full textThe behaviour of massive and massless test particles around asymptotically flat and spherically symmetric, charged black holes in the context of generalized dilaton-axion gravity in four dimensions is studied. All the possible motions are investigated by calculating and plotting the corresponding effective potential for the massless and massive particles as well. Further, the motion of massive (charged or uncharged) test particles in the gravitational field of charged black holes in generalized dilaton-axion gravity for the cases of static and nonstatic equilibrium is investigated by applying the Hamilton-Jacobi approach. © 2018 Susmita Sarkar et al
On star Rothberger spaces modulo an ideal
No full text[EN] In this article, we introduce the ideal star-Rothberger property by coupling the notion of a star operator to that of an ideal Rothberger space, after which some of its topological characteristics are analysed. By creating relationships between a numbers of topological features with structures similar to the ideal star-Rothberger space, we reinforce the concept. In order to illustrate the differences between a number of related topological properties, we also provide several counter examples. Certain preservation-related properties under subspaces and functions are investigated. Lastly we find a way to express ideal star-Rothberger space by means of families of closed sets by bringing some modifications to the SSI^I property. Sarkar, S.; Bal, P.; Datta, M. (2024). On star Rothberger spaces modulo an ideal. Applied General Topology. 25(2):407-414. https://doi.org/10.4995/agt.2024.20464OJS40741425
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Natural Medicinal Drug Delivery from 3D Printed Scaffold and Surface Modified TI6AL4v Implants for Chemoprevention, Osteogenesis and Anti-inflammation for Bone Tissue Engineering Application
No full textThe objective of this research is to understand the role of natural medicinal compounds (NMCs) in bone tissue engineering application by modifying their release kinetics from the porous 3DP scaffold, evaluating their in vitro osteoblast (hFOB) proliferating and osteosarcoma (MG-63) preventing efficacy, and investigating their effect on osteogenesis, anti-inflammation and wound healing in rat distal femur model.Curcumin, although exhibit excellent antioxidant, anti-inflammatory, anticancer and osteogenic activities, suffers from extremely poor bioavailability. To enhance its bioavailability and to provide higher release, poly-(I? -caprolactone) (PCL), poly-ethylene-glycol (PEG) and poly-lactide-co-glycolide (PLGA) is used as the polymeric system to enable the continuous release of curcumin from the hydroxyapatite matrix for 22 days. The presence of curcumin in interconnected 3DP TCP scaffolds results in enhanced bone formation after 6 weeks in rat distal femur model. Complete mineralized bone formation increases from 29.6% to 44.9% in curcumin-coated scaffolds compared to control. In a follow-up study, we have further improved the bioavailability of curcumin by encapsulating it in a liposome, followed by the incorporation onto 3DP TCP scaffolds with designed porosity. Interestingly, liposomal curcumin released from the 3DP scaffold shows significant cytotoxicity towards MG-63 cells, while it promoted hFOB cell viability and proliferation. Presence of genistein, a soy-isoflavone shows a 90% reduction in vitro MG-63 cell viability and proliferation after 11 days, while, daidzein, another primary isoflavone, promotes in vitro hFOB cellular activities in both static and dynamic cell culture. In vitro H&E staining confirms controlled co-delivery of soy-isoflavones from the 3DP scaffold significantly reduces inflammatory cell recruitment at the surgery site after 24 hours of implantation in a rat distal femur model.Another more stable form of calcium phosphate, hydroxyapatite (HA) is utilized as a coating on metallic orthopedic implants for load-bearing applications. Coated implants are loaded with curcumin and vitamin K2, which enhances in vitro hFOB cell activities, while lowers in vitro MG-63 cell proliferation after 3, 7 and 11 days. Modified Masson Goldner staining of the tissue-implant section shows an improved contact between tissue and implant in dual drug-loaded HA-coated Ti implants compared to control implants in in vitro rat distal femur model
The Role Of Oxidative Stress Following Antenatal Synthetic Glucocorticoid Therapy
No full textWe investigated the role of oxidative stress following sGC treatment in a guinea pig model of gestation through measures including: expression of antioxidant enzyme genes, protein carbonylation, and the glutathione ratio in the hippocampus, placenta, and liver of female and male fetuses treated with two courses of betamethasone in utero. Results indicated no significant differences in hippocampal or placental gene expression. Peroxiredoxin-6 expression was significantly downregulated in the male liver following sGC, but there were no differences in the female liver. There were no differences in protein carbonylation or glutathione ratio in the fetal placenta or liver. To investigate long-term outcomes of sGC exposure in utero, we used gene set enrichment analysis of post-natal day 40 female hippocampi, and found significant downregulation of a gene set for oxidative phosphorylation. These finding suggest that while the fetus is acutely protected from oxidative stress following sGC, there might be long-term programming of mitochondrial functions.M.Sc.2020-11-15 00:00:0
Multiscale approaches toward advanced lithium-ion battery: From nano to meso scale
No full text“Battery performance and its degradation are determined by various aspects such as the transport of ions and electrons through heterogeneous internal structures composed of constituent particles, kinetic reactions at the interfaces, and a corresponding interplay between mechanical, chemical, and thermal responses. Further, modern battery materials require a variety of engineering processes such as coating, doping and mixing. As a result, in order to fully understand the behavior of the battery material and improve battery performance, it is necessary to understand and control the individual particle behavior and then connect it to the electrode. This study elucidated the physical phenomena associated with coating and grain boundaries and addressed the impact on cell-level performance. We also studied how to improve battery performance by changing the material and geometry of electrode components. The study was divided into three topics. First, it has been proved how an optimal layer thickness of CeO2 layer by ALD is better than too think or too thick layer in terms of li-ion diffusion, transition metal-ion dissolution and mechanical damage. Second, it was shown that how grain boundary can improve the cell performance significantly. Grain-boundary possesses different diffusion co-efficient than the bulk and thus the performance is different than the electrodes where no grains are considered. Also, it was shown how grain boundary has impact on stress generation for both cathode and anode particles. Finally, an attempt has been made to use Ni-VOx based nanofiber supported with carbon nanofiber to be used as an anode for advanced li-ion battery. Not only the process is simple but also the cell showed improved reversibility at a current rate of 100 mA/g”--Abstract, page iv
Environmental regulation and development : a cross-country empirical analysis
No full textThe authors develop comparative indices of environmental policy and performance for 31 countries using a quantified analysis of reports prepared for the United Nations Conference on Environmental and Development. In cross-country regressions, they find a very strong, continuous association between their indicators and national income per capita, particularly when adjusted for purchasing power parity. Their results suggest a characteristic progression in development. Poor agrarian economies focus first on natural resource protection. With increased urbanization and industrialization, countries move from initial regulation of water pollution to air pollution control. The authors highlight the importance of institutional development. Environmental regulation is more advanced in developing countries with relatively secure property rights, effective legal and judicial systems, and efficient public administration.Public Health Promotion,Environmental Economics&Policies,Health Economics&Finance,Agricultural Research,Economic Theory&Research,Environmental Economics&Policies,Health Economics&Finance,Agricultural Research,Economic Theory&Research,Environmental Governance
Does strict employment protection discourage job creation? Evidence from Croatia
No full textEmployment protection legislation in Croatia is among the most strict in Europe. Firing is difficult and costly, and flexible forms of employment are limited. Is this apparent rigidity reflected-as one would expect based on standard economic theory-in low labor market dynamics? Is job creation low and hiring limited? Is the job security of insiders achieved at the cost of outsiders not being able to enter thelabor market? The author attempts to answer these questions by examining job flows. If the employment protection legislation is binding, then job and worker turnover should be low. He shows that this is indeed the case. Hiring is limited and the average job tenure is very long in Croatia. Job destruction is low, however job creation is still lower. The result is accumulation of unemployment, in large part due to new labor market entrants not being able to find a job. The high degree of job protection also seems to strengthen the bargaining position of insiders and results in relatively high wages. So, wages in Croatia are higher than among its competitors, even after adjusting for productivity. These high labor costs are likely to contribute to limited job creation in existing firms, but also are likely to discourage the entry of-and thus job creation in-new firms. The author presents evidence that firm growth has been indeed limited in Croatia, contributing to the low employment level. The author examines other potential causes of high unemployment in Croatia (the unemployment benefit system, labor taxation, the wage structure, and skill and spatial mismatches). He argues that they do not play a substantial part in accounting for poor labor market outcomes in Croatia. The author concludes that the stringent employment protection legislation is the key labor market institution behind low job creation and high unemployment. Based on this he recommends specific measures aimed at liberalizing the labor market to foster job creation and employment.Labor Management and Relations,Labor Policies,Labor Markets,Environmental Economics&Policies,Trade Finance and Investment,Labor Markets,Labor Management and Relations,Labor Standards,Banks&Banking Reform,Environmental Economics&Policies
Voucher privatization with investment funds : an institutional analysis
No full textCommon wisdom among post-socialist reformers has beento use voucher investment funds to provide the corporate governance needed to restructure newly privatized enterprises after mass privatization efforts. The idea has been that mass privatization would spread the ownership too wide and make corporate governance difficult. The author examines the likely institutional behavior of voucher funds and the possible effects of their development on a transition economy. Since most policy advice has been in favor of voucher privatization with investment funds, the author can be seen as playing the devil's advocate, but his argument is institutional, not statistical. Policymaking requires insight and foresight into how institutions will tend to function. He concludes that voucher funds will introduce a bias in the economy away from the real industrial sector toward an ersatz"financial sector"that will have little if any positive financial role but will be well-protected by friendly regulators. One long-term consequence of voucher privatization with investment funds, according to this view, is a de facto"industrial policy"of real sector decapitalization in favor of short-term rent-seeking by fund managers through board sinecures and lucrative side deals with portfolio companies and through financial market manipulation and paper entrepreneurship in the"financial sector."Without strong corporate governance from the funds and without stable ownership of their own, many enterprise managers will exploit the post-socialist version of the"separation of ownership and control"to grab what they can in the form of salaries, bonuses, perquisites, and side deals. The most likely results of the strategy of voucher privatization with investment funds may be a two-sided grab fest by fund managers and enterprise managers -- together with the accompanying drift, stagnation, and decapitalization of the privatized industrial sector.Economic Adjustment and Lending,Payment Systems&Infrastructure,International Terrorism&Counterterrorism,Economic Theory&Research,Banks&Banking Reform,International Terrorism&Counterterrorism,Banks&Banking Reform,Economic Adjustment and Lending,Environmental Economics&Policies,Economic Theory&Research
Effect of ion nonthermality on nonlinear dust acoustic wave propagation in a complex plasma in presence of secondary electron emission
No full textIn this paper we have investigated the effect of ion nonthermality on nonlinear dust acoustic wave propagation in a complex plasma in presence of secondary electron emission considering equilibrium dust charge positive. In space and astrophysical plasmas presence of nonthermal ions have been detected by satellite observations. This ion nonthermality modifies propagation characteristics of dust acoustic waves when dust grains are charged by secondary electron emission mechanism. In case of dust charging by secondary electron emission process two stable equilibrium dust charge states exist out of which one is negative and the other is positive. Here we have considered positive equilibrium dust charge state and both adiabatic and nonadiabatic dust charge variation. Our investigation shows that characteristics of both dust acoustic soliton and dust acoustic shock depend on the strength of the ion nonthermality along with secondary electron yield. Increase in both ion nonthermality and secondary electron yield help to retain the shape of compressive dust acoustic soliton when dust charge variation is adiabatic and to maintain oscillation of the dust acoustic shock when dust charge variation is nonadiabatic
Characterizations of strongly star-Rothberger spaces by means of sequential singletonic intersection property and selection principles
No full textIn this paper, using families of closed sets and a few modifications to the finite intersection features, we characterize the Rothberger Space and the Star-Rothberger Space. We also provide the selection principles that, in a reversed approach, can represent the Rothberger spaces and the star-Rothberger Spaces
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