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Search Results: 1 - 10 of 2620 matches for " Shiv Sankar Bhattacharya "
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Interpenetrating Polymer Networks as Innovative Drug Delivery Systems
Alka Lohani,Garima Singh,Shiv Sankar Bhattacharya,Anurag Verma
Journal of Drug Delivery , 2014, DOI: 10.1155/2014/583612
Abstract: Polymers have always been valuable excipients in conventional dosage forms, also have shown excellent performance into the parenteral arena, and are now capable of offering advanced and sophisticated functions such as controlled drug release and drug targeting. Advances in polymer science have led to the development of several novel drug delivery systems. Interpenetrating polymer networks (IPNs) have shown superior performances over the conventional individual polymers and, consequently, the ranges of applications have grown rapidly for such class of materials. The advanced properties of IPNs like swelling capacity, stability, biocompatibility, nontoxicity and biodegradability have attracted considerable attention in pharmaceutical field especially in delivering bioactive molecules to the target site. In the past few years various research reports on the IPN based delivery systems showed that these carriers have emerged as a novel carrier in controlled drug delivery. The present review encompasses IPNs, their types, method of synthesis, factors which affects the morphology of IPNs, extensively studied IPN based drug delivery systems, and some natural polymers widely used for IPNs. 1. Introduction In the present scenario polymers are among the largest volume chemical products in the world and the global market for polymer products is growing rapidly. Polymers have always been valuable excipients in tablet and capsule formulations [1] and also have shown excellent performance into the parenteral arena as blood circulation time enhancers [2] and are now capable of offering advanced and sophisticated functions such as controlled drug release and drug targeting [3]. In the recent decades, an ever growing demand for improved polymer properties has paved the development of the blending of polymer mixtures [4, 5]. In order to overcome the poor biological performance and to improve mechanical strength a new class of polymers has been introduced which are based on blending of either natural or synthetic polymers alone or in combinations. An interpenetrating polymer network (IPN) is defined as a blend of two or more polymers in a network with at least one of the systems synthesized in the presence of another [6]. This results in a formation of physically cross-linked network when polymer chains of the second system are entangled with or penetrate the network formed by the first polymer. Each individual network retains its individual properties so synergistic improvements in properties like strength or toughness can be seen [7]. An IPN can be distinguished from
Carbon Nanotubes: An Emerging Drug Carrier for Targeting Cancer Cells
Vaibhav Rastogi,Pragya Yadav,Shiv Sankar Bhattacharya,Arun Kumar Mishra,Navneet Verma,Anurag Verma,Jayanta Kumar Pandit
Journal of Drug Delivery , 2014, DOI: 10.1155/2014/670815
Abstract: During recent years carbon nanotubes (CNTs) have been attracted by many researchers as a drug delivery carrier. CNTs are the third allotropic form of carbon-fullerenes which were rolled into cylindrical tubes. To be integrated into the biological systems, CNTs can be chemically modified or functionalised with therapeutically active molecules by forming stable covalent bonds or supramolecular assemblies based on noncovalent interactions. Owing to their high carrying capacity, biocompatibility, and specificity to cells, various cancer cells have been explored with CNTs for evaluation of pharmacokinetic parameters, cell viability, cytotoxicty, and drug delivery in tumor cells. This review attempts to highlight all aspects of CNTs which render them as an effective anticancer drug carrier and imaging agent. Also the potential application of CNT in targeting metastatic cancer cells by entrapping biomolecules and anticancer drugs has been covered in this review. 1. Introduction After the discovery of the third allotropic form of carbon fullerene in 1991, Sumio Iijima identified a new structural form of this allotrope, the cylindrical fullerene and named them as carbon nanotubes (CNTs) [1]. CNTs are graphene sheets rolled into a seamless cylinder that can be open ended or capped, having a high aspect ratio with diameters as small as 1nm and a length of several micrometers [2]. Depending on the number of sheets rolled into concentric cylinders, there are two broad categories of CNTs, namely, single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) (Figure 1). SWCNTs are made up of single graphene layer wrapped into a hexagonal close-packed cylindrical structure whose diameter varies from 0.4 to 3.0?nm and length ranges from 20 to 1000?nm and are held together by Vander Waals forces, which makes them easily twistable and more pliable [3]. SWCNTs are produced by the electric arc [4], laser ablation [5], chemical vapor deposition (CVD) [6], and gas-phase catalytic processes (HiPco or high-pressure CO conversion) [7]. Figure 1: Carbon nanotube: (a) single walled carbon nanotube and (b) multiwalled carbon nanotube. MWCNTs consist of several coaxial cylinders, each made of a single graphene sheet surrounding a hollow core. The outer diameter of MWCNTs ranges from 2 to 100?nm, while the inner diameter is in the range of 1–3?nm, and their length is 1 to several m [8]. Electric arc [9] and chemical vapor deposition (CVD) [10, 11] are the main techniques for their production. Owing to the sp2 hybridization in MWCNTs, a delocalized electron cloud
Effect of mineral oxides on slag formation tendency of Mae Moh lignites
Anuwat Luxsanayotin,Suneerat Pipatmanomai,Sankar Bhattacharya
Songklanakarin Journal of Science and Technology , 2010,
Abstract: Slagging is one of major ash deposition problems experienced in the boilers of coal–fired power plants especially theplants that use lignite, like Mae Moh lignites. The occurrence of slag is a complex phenomenon depending on several factorssuch as ash properties, furnace operating conditions, and coal properties. The main objective of this work is to study theeffect of mineral components in Mae Moh lignite on ash fusion temperatures (AFTs), which is commonly used as a keyindicator for slag formation tendency under pulverized combustion conditions. Two Mae Moh lignites from the coal seamsplanned to be used in the future were selected for the study to represent low CaO and high CaO lignite. The two lignites,namely K1 and K3, have 3.6 and 40.4 wt% CaO in ash, respectively. The AFT characterization shows that their initial deformationtemperatures (ITs) were almost identical and considered as low for the typical flue gas temperature in the radiationsection of Mae Moh boilers, i.e. 1050-1100°C. These observed similar ITs were rather unexpected, especially for K1 consideringits sufficiently low base to acid (B/A) ratios. The X-ray diffraction analyses evidently show the presence of illite, pyriteand anhydrite in K1, which explains the observed lower IT of the sample. Anhydrite, which is known to lower the ITs, is alsothe most abundant mineral in K3. Washing the lignite samples with HCl can significantly reduce CaO, MgO, and SO3 contentin the ash but not Fe2O3 as it is present in the form of pyrite. The addition of Al2O3, SiO2 and Fe2O3 can help increase AFTs ofthe studied samples. The Al2O3 addition gives the strongest effect on increasing AFTs, especially for the sample with lowAl2O3 content. When the CaO is added to the low CaO samples, the fluxing effect will initially occur. However, when the CaOcontent is higher than a critical value (i.e. CaO > 38%), the effect of its high melting point will dominate hence the AFTsincreased. Ternary phase diagrams of CaO-SiO2-Al2O3 and Fe2O3-SiO2-Al2O3 system were constructed based on the obtainedash composition and IT data to investigate the effect of SiO2/Al2O3 ratio and basic oxide composition (CaO or Fe2O3). Theupper limit of the ITs measured from lignites supplied to the power plant during the severe slagging period, i.e. 1220°C, wasused as a rough indication of slag formation propensity.
Prevalence of ischemic heart disease among urban population of Siliguri, West Bengal
Mandal Sukanta,Saha Joyti,Mandal Sankar,Bhattacharya Rudra
Indian Journal of Community Medicine , 2009,
Abstract: Objectives: To determine the prevalence of ischemic heart disease and the associated risk factors among the urban population of Siliguri. Materials and Methods: A cross-sectional survey of a random sample of the population aged ≥40 years old in the Municipal Corporation area of Siliguri. Study variables were age, sex, occupation, addiction, food habit, physical activity, body mass index, blood pressure, and electrocardiogram change. Results: Out of 250 individuals who took part in this study, 29 (11.6%) had ischemic heart disease (IHD) and 118 (47.2%) had hypertension. Males had a higher (13.5%) prevalence of IHD than females (9.4%). About 5% of the patients had asymptomatic IHD. IHD among the study population is significantly associated with hypertension and smoking.
Optimal quantum violation of Clauser-Horne-Shimony-Holt like steering inequality
Arup Roy,Some Sankar Bhattacharya,Amit Mukherjee,Manik Banik
Mathematics , 2015, DOI: 10.1088/1751-8113/48/41/415302
Abstract: We study a recently proposed Einstein-Podolsky-Rosen steering inequality [arXiv- 1412.8178 (2014)]. Analogous to Clauser-Horne-Shimony-Holt (CHSH) inequality for Bell nonlocality, in the simplest scenario, i.e., 2 parties, 2 measurements per party and 2 outcomes per measurement, this newly proposed inequality has been proved to be necessary and sufficient for steering. In this article, using an equivalence between measurement incompatibility (non joint measurability) and steering, we find the optimal violation amount of this inequality in quantum theory. Interestingly, the optimal violation amount matches with optimal quantum violation of CHSH inequality, i.e., Cirel'son quantity. We further study the optimal violation of this inequality for different bipartite quantum states. To our surprise we find that optimal violation amount is different for different $2$-qubit pure entangled states, which is not the case for all other existing steering inequalities.
On Tate’s Proof of a Theorem of Dedekind  [PDF]
Shiv Gupta
Open Journal of Discrete Mathematics (OJDM) , 2018, DOI: 10.4236/ojdm.2018.83007
Abstract: In this note we give a complete proof of a theorem of Dedekind.
Irreducible Polynomials in Ζ[x] That Are Reducible Modulo All Primes  [PDF]
Shiv Gupta
Open Journal of Discrete Mathematics (OJDM) , 2019, DOI: 10.4236/ojdm.2019.92006
Abstract: The polynomial x4+1 is irreducible in Ζ[x] but is locally reducible, that is, it factors modulo p for all primes p. In this paper we investigate this phenomenon and prove that for any composite natural number N there are monic irreducible polynomials in Ζ[x] which are reducible modulo every prime.
Classical Interpretations of Relativistic Phenomena  [PDF]
Sankar Hajra
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.32026
Abstract: Electric charges, electric & magnetic fields and electromagnetic energy possess momentum and energy which we could experience with our sense organs. Therefore, all these are real physical entities (objects). All physical objects are sub- ject to gravitation. Therefore, electromagnetic entities should similarly be subject to gravitation. In this paper, we have shown that classical physics with this simple consideration is equivalent to the theory of relativity—special & general— to explain many puzzling electrodynamic as well as gravitational phenomena.
Classical Derivation of Auxiliary Lorentz Transforms: Their Relations with Special Relativity  [PDF]
Sankar Hajra
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.310180
Abstract: In this paper we have given a direct deduction of the auxiliary Lorentz transforms from the consideration of Maxwell. In the Maxwell’s theory, if c is considered to be the speed of light in ether space, his equations should be affected on the surface of the moving earth. But curiously, all electromagnetic phenomena as measured on the surface of the moving earth are independent of the movement of this planet. To dissolve this problem, Einstein (1905) assumes that Maxwell’s equations are invariant to all measurers in steady motion which acts as the foundation of Special Relativity. This assumption of Einstein is possible when all four auxiliary Lorentz transforms are real. There is not a single proof that could properly justify Einstein’s assumption. On the contrary it is now known that classical electrodynamics could easily explain all relativistic phenomena rationally.
Redefining the Event Horizon  [PDF]
Shiv Raj Aryan
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.34045
Abstract:

Presented herein is a new and independent derivation of equation for the radius of Black Holes, i.e. the event horizon of black holes. The equation has been derived by formulating the relativistic equation of escape velocity derived from the relativistic equations for gravitational potential and kinetic energy. Based upon that, it is now shown that the actual size of a black hole, as determined by its event horizon, is exactly half the value predicted by the escape velocity equation used in the Newtonian mechanics. It proves that the actual radius of a black hole is exactly one half of the Schwarzschild radius.

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