Comparative experimental and Density Functional Theory (DFT) study of the physical properties of MgB2 and AlB2

In present study, we report an inter-comparison of various physical and electronic properties of MgB2 and AlB2. Interestingly, the sign of S(T) is +ve for MgB2 the same is -ve for AlB2. This is consistent our band structure plots. We fitted the experimental specific heat of MgB2 to Debye Einstein model and estimated the value of Debye temperature (theta) and Sommerfeld constant (gamma) for electronic specific heat. Further, from gamma the electronic density of states (DOS) at Fermi level N(EF) is calculated. From the ratio of experimental N (EF) and the one being calculated from DFT, we obtained value of Lembda to be 1.84, thus placing MgB2 in the strong coupling BCS category. The electronic specific heat of MgB2 is also fitted below Tc using pi-model and found that it is a two gap superconductor. The calculated values of two gaps are in good agreement with earlier reports. Our results clearly demonstrate that the superconductivity of MgB2 is due to very large phonon contribution from its stretched lattice. The same two effects are obviously missing in AlB2 and hence it is not superconducting. DFT calculations demonstrated that for MgB2 the majority of states come from Sigma and Pi 2p states of boron on the other hand Sigma band at Fermi level for AlB2 is absent. This leads to a weak electron phonon coupling and also to hole deficiency as Pi bands are known to be of electron type and hence obviously the AlB2 is not superconducting. The DFT calculations are consistent with the measured physical properties of the studied borides, i.e., MgB2 and AlB2Comment: 16 pages Text + Figs: comments/suggestions welcome ([email protected])/www.freewebs.com/vpsawana

Structure and Optical Properties of Polycrystalline InxSb30 – xSe70 (0 ≤ x ≤ 25) Chalcogenide Alloys

The spectroscopic studies of various physical properties of glassy and polycrystalline chalcogenide alloys are important due to their importance as active materials in various solid state devices. The composition dependence of these properties are explained on the basis of coordination number, but the splitting of this effect from the nature of additive is imperative for furthering the understanding of these systems. In the present work, the structural and spectroscopic investigations of melt quenched bulk In-Sb-Se chalcogenide alloys have been studied by XRD, RAMAN and optical spectroscopic techniques. The XRD study reveals the polycrystalline nature of the samples. The composition was analysed using the energy dispersive X-ray spectroscopy technique. The XRD study reveals the crystallization of Sb2Se3 and β-In2Se3 phases while the increase in the intensity for β-In2Se3 phase has been observed with the increase in indium content. The RAMAN spectra also reveal the formation of chalcogenide based Sb and In structural units. The diffused reflectance spectrum was used to calculate the optical absorption in 800-1500 nm spectral region and used to study the composition dependence of the optical gap in these samples. The results have been discussed in conjunction with the heterogeneous phases; density of defect states; electronegativity and average mean bond energy for these polycrystalline alloys

FUTURISTIC SCOPE OF STEM CELLS IN MEDICINE

ABSTRACTThe most potential application of the stem cells (SCs) in human beings lies in their ability to regenerate cells and tissues. They differentiate themselvesinto specific cell type, thereby availing remarkable source of replacement cells and tissues. They differentiate themselves into specific cell types,thereby availing renewable source of replacement cells and tissues. Their potential of regeneration has now opened many avenues in the field ofmedical science and research. As a therapeutic adjuvant in near future, the SCs will emerge as an efficient technique to completely heal a number ofdiseases including diabetes, heart diseases and strokes, osteoarthritis, rheumatoid arthritis, and macular degeneration. The researches, which areunderway, some of them will surely be proved as safe and effective SC treatment in the market in due course of time.Keywords: Stem cells, Medicine, Embryonic cells, Heart disease

Epoxy-glass Microballoon Syntactic Foams for Blast Mitigating Applications

Polymeric syntactic foams refer to a class of cellular material created using preformed hollow spheres bound together with a polymeric matrix. These cellular materials possess exceptional ability to respond against high impact dynamic loads. This paper is an attempt to fabricate polymeric syntactic foams of epoxy containing hollow glass microballoon at varying loading (40 % - 60 %) and explore their potential towards blast mitigation. The tensile, compressive and flexural strength were found to be inversely proportional to the microballoon loading in the quasi-static regime. The strain rate sensitivity of the foams was confirmed by performing high strain rate studies using split hopkinson pressure bar. The flow stress of these foams was found to increase with increasing strain rates. The syntactic foams were subjected to controlled transient blast loadings using a shock tube. The samples remained intact and no strain was observed on the strain gauge, even under a blast load of ~ 90 psi, which clearly highlight their potential as core materials for blast mitigating applications

Studies on diversity and abundance of parasitoids of Chromatomyia horticola (Goureau) (Agromyzidae: Diptera) in north-western Himalayas, India

Pea leafminer, Chromatomyia horticola (Goureau) is an important pest of many vegetable and ornamental crops. The present investigation was carried out to study the parasitoid diversity of this pest in different agroclimatic conditions of Himachal Pradesh, India. Sixteen species of parasitoids viz. Diglyphus horticola Khan, Diglyphus isaea (Walker), Zagrammosoma sp., Pnigalio sp., Quadrastichus plaquoi Reina and LaSalle, Asecodes erxias (Walker), Closterocerus sp., Neochrysocharis formosa (Westwood), Chrysocharis sp, Chrysocharis indicus Khan, Pediobius indicus Khan (Eulophidae), Opius exiguus (Wesmael), Dacnusa sp. (Braconidae), Cyrtogaster sp., Sphegigaster sp. (Pteromalidae), and Gronotoma sp. (Figitidae) were recorded parasitizing C. horticola in different agro-climatic zones of Himachal Pradesh. Agro-climatic zone II (sub-temperate mid-hills) was the richest in parasitoid diversity (14 species) followed by zone I (11 species), zone III (7 species) and zone IV (4 species) which are characterized by sub-tropical sub-montane, wet temperate high hills and dry temperate high hills, respectively. Shannon diversity index, species richness, species evenness and species dominance varied from 0.69-1.71, 1.39-2.64, 0.50-0.71 and 0.29-0.50, respectively. D. isaea and D. horticola were the dominant parasitoids of C. horticola contributing 41.46-80.15 and 9.16-50.65 per cent of the total parasitization, respectively, in different agro climatic zones. The study highlights the role of different parasitoids in natural control of the leaf miner and will be useful for designing the IPM strategies for the pest

Bulk Superconductivity in Bismuth-oxy-sulfide Bi4O4S3

Very recent report [1] on observation of superconductivity in Bi4O4S3 could potentially reignite the search for superconductivity in a broad range of layered sulphides. We report here synthesis of Bi4O4S3 at 5000C by vacuum encapsulation technique and basic characterizations. Detailed structural, magnetization, and electrical transport results are reported. Bi4O4S3 is contaminated by small amounts of Bi2S3 and Bi impurities. The majority phase is tetragonal I4/mmm space group with lattice parameters a = 3.9697(2){\AA}, c = 41.3520(1){\AA}. Both AC and DC magnetization measurements confirmed that Bi4O4S3 is a bulk superconductor with superconducting transition temperature (Tc) of 4.4K. Isothermal magnetization (MH) measurements indicated closed loops with clear signatures of flux pinning and irreversible behavior. The lower critical field (Hc1) at 2K, of the new superconductor is found to be ~39 Oe. The magneto-transport R(T, H) measurements showed a resistive broadening and decrease in Tc (R=0) to lower temperatures with increasing magnetic field. The extrapolated upper critical field Hc2(0) is ~ 310kOe with a corresponding Ginzburg-Landau coherence length of ~100{\AA} . In the normal state the {\rho} ~ T2 is not indicated. Our magnetization and electrical transport measurements substantiate the appearance of bulk superconductivity in as synthesized Bi4O4S3. On the other hand same temperature heat treated Bi is not superconducting, thus excluding possibility of impurity driven superconductivity in the newly discovered Bi4O4S3 superconductor.Comment: 12 pages Text + Fig

A REVIEW ON CONTRIBUTION OF ACHARYA SUSHRUTA IN EMERGENCY SURGICAL CONDITIONS

Acharya Sushruta was the ancient Indian surgeon and also called as Father of Surgery. In ancient era when surgery was in its early childhood stage or not even heard of in other parts of the world, Acharya Sushruta performed surgery in various emergency conditions like Chhidrodara (intestinal perforation), Baddhgudodara (intestinal obstruction), Ashmari (urolithiasis), Sadyo Vrana (traumatic wound), etc. In his text Sushruta Samhita, he described all such types of diseases and their emergency surgery. His basic principles of plastic surgeries and concept of anesthesia are the privilege to emergency surgery. Ashtavidha Shastra Karma (8 types of surgical procedures), trauma bandage, emergency trauma suturing, management of Raktasrava (hemorrhage), replacement of blood volume, etc., are the basic principles of emergency surgery and given by Acharya Sushruta first. There are various advanced types of surgical procedures available in modern science for emergency conditions, but many of these surgical procedures are still following the basic principles as given by Acharya Sushruta and even after their development, in certain conditions they are still deprived of. So this paper focuses on review on the contribution of Acharya Sushruta in emergency surgical conditions