A first principles study of wurtzite-structure MnO

We present results of a density functional theory study of MnO in the wurtzite structure. Our motivation is provided by recent experiments reporting ferromagnetism in Mn-doped wurtzite structure ZnO. We find that wurtzite MnO a) is not strongly energetically disfavored as compared with the ground state rocksalt MnO, b) shows strong magnetostructural coupling and c) has a piezoelectric response that is larger than that of ZnO. These predictions augur well for the creation of ferromagnetic piezoelectric semiconductor based on Mn-doped ZnO

FUSOGENIC LIPOSOME FOR THE TREATMENT OF FUNGAL MENINGITIS: AN OVERVIEW

Fungal meningitis is an infection which is caused by fungus which spreads through the blood to the spinal cord. People with weakened immunity get this disease easily like persons with AIDs, etc. To make sure the disease is fungal meningitis, a sample is taken from the cerebrospinal fluid and it is sent to the laboratory. Usually, fungal meningitis is not mediated from person to person, but it is caused when a fungi are inhaled from the surrounding and spread into the blood to the central nervous system. Normally medications such as vaccines, IV, and oral suspensions are given to the people for curing fungal meningitis. Commonly used drugs are Amphotericin B and fluconazole oral suspension. Amphotericin B is an antifungal, antiprotozoal, and hydrophobic drug. However, these drugs cannot give a directly as medication therapy for the patients, because it offers toxic effect and side effects, absorption rate is slower, and crossing the blood–brain barrier (BBB) is getting difficult. Adverse effects can be minimized with the application of nanotechnology. Therefore, in human medical services, the availability of molecular nanotechnology will provide rapid progress. Nanoparticle (NP) systems help to improve the solubility of poorly water-soluble drugs which has been explained using Noyes–Whitney equations. Nanoparticles offers several advantages as a drug delivery system, such as better drug bioavailability, reduction of dosing frequency enables them for the betterment of diseases, can cross the BBB, and it is very cost-effective. Types of NP include polymeric NP, carbon nanotubes, metallic structures, nanocrystals, and fusogenic liposomes. Fusogenic liposomes are a peculiar class of phospholipid vesicles. The fusogenic liposomes can deliver encapsulated NP into the targeted sites and also can cross the BBB. On comparing with cationic liposomes, fusogenic liposomes are more effective as well as rapid in the drug delivery

Antagonistic activity of coconut rhizospheric and endophytic Bacillus spp. against Ganoderma applanatum and Thielaviopsis paradoxa

A screening study was carried out to detect the antagonistic potential of Bacillus spp. against Ganoderma applanatum and Thielaviopsis paradoxa, fungal pathogens of coconut. A total of 327 heat resistant, endospore producing bacilli were isolated from the rhizospheric soil and roots of coconut growing in Kerala, Tamil Nadu, Karnataka, Andhra Pradesh and Maharashtra. All the isolates were tested for antifungal activity against G. applanatum and T. paradoxa by dual cultural technique on nutrient agar medium. The zone of inhibition was measured and percentage of inhibition was calculated. More than 90 % of the rhizospheric and root endophytic isolates were found to effectively inhibit the mycelial growth of G. applanatum, with a maximum inhibition zone of 12 mm and percentage inhibition ranging from 44 to 91. About 86 % of the isolates inhibited the mycelial growth of T. paradoxa, with a maximum inhibition zone of 14 mm and percentage inhibition ranging from 42 to 93. Further tests of potent antagonists revealed that more than one mode of mechanisms like production of chitinase, siderophores, HCN, antibiotics, ammonia, β-1,3- glucanase and salicylic acid may be involved in the antagonistic activities. The results of this study revealed 13 Bacillus spp. having potential for use as biocontrol agents against G. applanatum and T. paradoxa, fungal pathogens of coconut

Magnetic interactions in transition metal doped ZnO : An abinitio study

We calculate the nature of magnetic interactions in transition-metal doped ZnO using the local spin density approximation and LSDA+\textit{U} method of density functional theory. We investigate the following four cases: (i) single transition metal ion types (Cr, Mn, Fe, Co, Ni and Cu) substituted at Zn sites, (ii) substitutional magnetic transition metal ions combined with additional Cu and Li dopants, (iii) substitutional magnetic transition metal ions combined with oxygen vacancies and (iv) pairs of magnetic ion types (Co and Fe, Co and Mn, etc.). Extensive convergence tests indicate that the calculated magnetic ground state is unusually sensitive to the k-point mesh and energy cut-off, the details of the geometry optimizations and the choice of the exchange-correlation functional. We find that ferromagnetic coupling is sometimes favorable for single type substitutional transition metal ions within the local spin density approximation. However, the nature of magnetic interactions changes when correlations on the transition-metal ion are treated within the more realistic LSDA + \textit{U} method, often disfavoring the ferromagnetic state. The magnetic configuration is sensitive to the detailed arrangement of the ions and the amount of lattice relaxation, except in the case of oxygen vacancies when an antiferromagnetic state is always favored.Comment: 11 pages, 17 figure

In vitro antagonism of rhizospheric fluorescent pseudomonads of coconut against Ganoderma applanatum and Thielaviopsis paradoxa, fungal pathogens of coconut

A total of 156 fluorescent pseudomonads were tested for antagonistic activity towards G. applanatum and T. paradoxa in a dual-plate assay on King’s B agar plates. Eight percent of the total fluorescent pseudomonads showed antagonism towards G. applanatum (inhibition ranging from 39% to 73%) and 16% of the isolates inhibited T. paradoxa in the range of 20% - 76%. Moreover, eight percent of the fluorescent pseudomonads significantly inhibited both pathogens tested. They were found to possess some important biocontrol traits such as HCN, siderophores, ammonia and antibiotics. Among them fluorescent Pseudomonas spp. KiSF 17 and KiSF 16 exhibited strong antagonistic activity. They were identified as P. aeruginosa by Biolog® GEN III microplate identification system and confirmed by 16S rDNA sequencing. The present studies revealed the survival of useful bacterial antagonists in the rhizosphere of coconut palm, which have the potential to be used as a biocontrol agent

Thermoelectric properties of minerals with the mawsonite structure

Synthetic copper sulfides have emerged as promising non-toxic and low-cost materials for thermoelectric power generation in low-grade waste heat recovery systems. Similarly to tetrahedrite and colusite, mawsonite \ce{Cu6Fe2SnS8} exhibits a modified corner sharing Cu-S tetrahedral network which usually leads to p-type character and low thermal conductivity. In order to explore the applicative potential of mawsonite, we studied the band structure, the phonon dispersions, the electronic and transport coefficients as well as the effect of isovalent substitutions of Fe, Sn and S. The combined analysis of electronic and vibrational properties highlights the role of the weakly bonded copper component in achieving a very low thermal conductivity. We also demonstrate that the Cu-S bond builds a 2D conductive network where the contribution from other elements is negligible. Magnetic calculations point to an anti-ferromagnetic ground state substantially affected by the covalency of the bonds with the conductive plane. The chemical substitution of Fe with Ni leads to non-magnetic metals whereas \ce{Cu6Fe2SnSe8}, \ce{Cu6Fe2PbS8}, and \ce{Cu6Fe2GeX8} with X=S, Se, and Te are semiconductors