Large Magnetoresistance and Jahn Teller effect in Sr2_2FeCoO6_6

Neutron diffraction measurement on the spin glass double perovskite Sr$_2$FeCoO$_6$ reveals site disorder as well as Co$^{3+}$ intermediate spin state. In addition, multiple valence states of Fe and Co are confirmed through M\"{o}ssbauer and X-ray photoelectron spectroscopy. The structural disorder and multiple valence lead to competing ferromagnetic and antiferromagnetic interactions and subsequently to a spin glass state, which is reflected in the form of an additional $T$-linear contribution at low temperatures in specific heat. A clear evidence of Jahn-Teller distortion at the Co$^{3+}$-O$_6$ complex is observed and incorporating the physics of Jahn-Teller effect, the presence of localized magnetic moment is shown. A large, negative and anomalous magnetoresistance of $\approx$ 63% at 14K in 12T applied field is observed for Sr$_2$FeCoO$_6$. The observed magnetoresistance could be explained by applying a semi-empirical fit consisting of a negative and a positive contribution and show that the negative magnetoresistance is due to spin scattering of carriers by localized magnetic moments in the spin glass phase

A PERSPECTIVE REVIEW ON APPLICATIONS OF NANOPARTICLE MEDIATED DRUG DELIVERY TO THE CNS

Delivery of drugs into the brain is one of the most interesting and challenging areas of research. The blood-brain barrier (BBB) is a highly selective semipermeable membrane that separates blood from the brain in the central nervous system. It acts as a barrier to protect the brain from microbes, neurotoxins and other chemical substances and also blocks the entry of many drugs into the brain. An estimated 6.8 billion people die every year from CNS diseases like Parkinson’s disease, Alzheimer’s disease, sclerosis, brain stroke, dementia and others. According to WHO, one billion people are affected worldwide, about 50 million suffer from epilepsy and 24 million suffer from Alzheimer and other dementias. This indicates the importance of the delivery of drugs into the brain for treating various neurological diseases and psychological disorders. In drug targeting, a concept was introduced by Dr. Paul Ehrlich as a ‘magic bullet’ that gave tremendous hope for the researches to deliver drugs into the brain. This review discuses about various drug targeting strategies and applications of nanotechnology in designing drug delivery systems with the ability to cross through the BBB for treating neurological diseases

Modeling and Performance Analysis of New Cuk Converter Topology for Photovoltaic Applications

Photovoltaic (PV) is a technical name in which radiant (photon) energy from the sun is converted to direct current (dc) Electrical Energy. PV power output is still low, continuous efforts are taken to develop the PV converter and controller for maximum power extracting efficiency and reduced cost factor. The maximum power point tracking (MPPT) is a process which tracks one maximum power point from array input, varying the ratio between the voltage and current delivered to get the most power it can. The selection of right converter for different application is a key factor for the optimum performance of the photo voltaic system. This paper details the study on state of the art in research works on Cuk power converters and their characteristics. A new cuk converter topology has also been proposed for the optimal performance of the photovoltaic system. Modeling of the PV array and simulation of basic cuk converter and the proposed cuk converter is carried out in Matlab/Simulink Software. Index Terms - PV Module, MPPT, Incremental Conductance (IC) Algorithm, Cuk converter, Optimal performanc

Cerebral protection for the preclinical evaluation of a vascular graft in sheep carotid artery model

A protocol for cerebral protection without systemic hypothermia to aid the safe, smooth and fast recovery of sheep used for the preclinical evaluation of a prosthetic vascular graft in the carotid artery is presented in this study. Ten adult Ramnad white sheep (33.

EVALUATION OF A NOVEL, NATURAL LOCUST BEAN GUM AS A SUSTAINED RELEASE AND MUCOADHESIVE COMPONENT OF TIZANIDINE HYDROCHLORIDE BUCCAL TABLETS

Mucoadhesive polymers that bind to the gastric mucins or epithelial cell surface are useful in drug delivery for the purpose of increasing the intimacy andduration of contact of the drug with the absorbing membrane. Mainly synthetic polymers are in use for this purpose. Probably the biodegradability of thesynthetic polymers is questionable. In the present work mucoadhesive buccal tablets of tizanidine hydrochloride were prepared using locust bean gumthat has better mucoadhesive property than synthetic polymer. The in vitro adhesive and mucoadhesive strength and swelling property of mucoadhesivmaterial locust bean gum were evaluated by Share Stress and Park and Robinson methods. Buccal formulations of tizanidine hydrochloride tablets werprepared using locust bean gum, and thickness, hardness, friability, weight variation, and assay of tablets were tested. The in vitro drug release studof tizanidine hydrochloride exhibited extended drug release profile for tablets prepared. Higuchi and Peppas data reveal that the drug released by nonFickiandiffusion mechanism. The presentstudyshowsthat formulationcontaining 50% locust bean gum havegreatermucoadhesivepropertythan allotherformulation.Increasein concentrationof locust bean gum increasesin the bioadhesivestrengthand swellingratioin the 50mgof locust bean gum.Keywords: Mucoadhesive, Tizanidine hydrochloride, Tablets, Locust bean gum

Incidence of Chirodiscoides caviae in Laboratory Rats-Screening, Identification and Treatment

This is a report on the incidence and treatment of the guinea pig fur mite Chirodiscoides caviae, which  was so far considered as host specific, in a conventional colony of laboratory rats. Chirodiscoides caviae  infestation in laboratory rats was accidentally observed during the screening of Syphacia obvelata by the  peri-anal cellophane tape test (CTT). The organism was identified by comparing the morphology described  by various researchers and was differentially diagnosed from other common mites of rat, Radfordia ensifera  and Notoedres muris. The adult male mites (n=15) were of 330.2±13.3 μm long and the females (n=15)  495.5±25.2 μm. Later on, the entire rat colony consisting of Wistar, Sprague Dawley and Spontaneously  Hypertensive Rats (SHR) and the mice colony of Balb/c and Swiss Albino were randomly sampled and  screened for the presence of the mite by the cellophane tape technique. All the rat strains were found positive  for C. caviae infestation, which was more concentrated towards the posterior region of the body and,  collectively, the screening results of C. caviae revealed that the posterio-dorsal and peri-anal regions are  most suitable for sampling-suggesting that, the infestation pattern of C. caviae in rats has similarities to that  of guinea pigs. Interestingly the mice colony was found free from the infestation. The Cellophane tape test was found to be an easier method than fur examination by hair plucking and equally  accurate for screening of fur mite in a colony of laboratory rats. No clinical symptoms were observed in  any of the animals in the colony, which possessed infestation. The facility strictly practised physical separation  of animals by species, which pointed to the only possibility of cross infestation being through indirect  contact between guinea pigs and laboratory rats and thereby questioning previous reports on the mode of  transmission of C. caviae. The entire colony was effectively treated with 0.2% Ivermectin spray followed by  1% spray in an interval of 2 weeks. This report is the first one, which demonstrates the guinea pig fur mite  in laboratory rats. It also questions the so far documented “host specificity” and “direct contact” mode of  transmission and demonstrates indirect contact as a possible mode of transmission.

A Finite Element Analysis of Orthodontic Single Buccal Tube with Hook, on Molar Tooth Movement

Buccal tubes are usually attached to the molar bands during orthodontics fixed appliance therapy. The molar tooth provides area of anchorage and forces are applied from the buccal tube hook. The hook is positioned in the mesial part of the tube, and force is applied (minimum 50 grams to maximum 150 grams) on hook. Because of the applied force on hook, there is a reactive change in molar position in the form of translation. The aim of this work is to show the molar tooth mesial translation for the applied force on the buccal tube hook

Development of Dexamethasone Sodium Phosphate Nanoparticles for the Post Cataract Treatment

This study was to investigate ocular irritation in rabbits following powder administration. Timolol maleate (TM) powder was administered to pigmented lop rabbits. Both pure TM powder and freeze-dried with PVP-polymer (2.4% of mass) were tested in 1.0- and 0.1-mg doses. Additionally, 4 rabbits received 0.1 mg of the pure powder 3 times a day for 8 d. Redness of the bulbar conjunctiva and the amount of discharge was rated from photographs (0–3 points, randomized and masked evaluation). The 8-d experiment additionally included examination with a slit lamp and examination of heamatoxylin-eosin stained sections of eyes with light microscopy. No serious or irreversible signs of irritation were noted. Doses of 1.0 mg were more irritating than 0.1-mg doses. There was no detectable difference in irritation between pure or freezedried powder. Slit-lamp examination, surface photographs and histology showed a negligible difference between drug and control eyes following the 8-d experiment. The results suggest that 0.1 mg of timolol powder does not irritate the eye and that testing topical timolol powder in humans is feasible. The present paper concerns both the optimization of Dexamethasone (DXM) entrapment and its release from biodegradable poly (d, l-lactide-coglycolide) (PLGA) nanoparticles prepared by the solvent evaporation process. Since the addition of DXM induced the formation of drug crystals beside the nanoparticle suspension, the influence of several parameters on DXM encapsulation was investigated such as the type of organic solvent and polymer, the DXM initial mass, the evaporation rate of the solvent, the continuous phase saturation and the incorporation of a lipid in the polymer. Nanoparticle size and zeta potential were not modified in the presence of DXM and were respectively around 230 nm and −4mV. The highest drug loading was obtained using 100 mg PLGA 75:25 in a mixture of acetone-dichloromethane 1:1 (v:v) and 10 mg of DXM. The drug was completely released from this optimized formulation after 4 h of incubation at 37 ◦C. Neither the evaporation rate of the organic solvent, nor the aqueous phase saturation with salt or the incorporation of 1mg 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) within the nanoparticles modified the encapsulation efficiency. Differential scanning calorimetric (DSC) and X-ray diffraction (XRD) demonstrated that the drug was molecularly dispersed within the nanoparticles whereas the non-encapsulated DXM crystallized. These results demonstrate the feasibility of encapsulating Dexamethasone and its subsequent delivery