Multiple magnetic transitions and magnetocaloric effect in Gd1-xSmxMn2Ge2 compounds

Magnetic and magnetocaloric properties of polycrystalline samples of Gd1-xSmxMn2Ge2 have been studied. All the compounds except GdMn2Ge2 show re-entrant ferromagnetic behavior. Multiple magnetic transitions observed in these compounds are explained on the basis of the temperature dependences of the exchange strengths of the rare earth and Mn sublattices. Magnetocaloric effect is found to be positive at the re-entrant ferromagnetic transition, whereas it is negative at the antiferro-ferromagnetic transition. In SmMn2Ge2, the magnetic entropy change associated with the re-entrant transition is found to decrease with field, which is attributed to the admixture effect of the crystal field levels. The isothermal magnetic entropy change is found to decrease with increase in Sm concentration.Comment:

Heat capacity and magnetocaloric effect in polycrystalline Gd1-xSmxMn2Si2

We report the magnetocaloric effect in terms of isothermal magnetic entropy change as well as adiabatic temperature change, calculated using the heat capacity data. Using the zero field heat capacity data, the magnetic contribution to the heat capacity has been estimated. The variations in the magnetocaloric behavior have been explained on the basis of the magnetic structure of these compounds. The refrigerant capacities have also been calculated for these compounds

Analysis of lead and arsenic in cosmetics and assessment of students awareness about cosmetic toxicity

Background: Many people believe that all cosmetics are safe but there are number of studies proving that majority of the cosmetics contains heavy metals or other chemicals. In this study we selected two heavy metals arsenic and lead because as per the Indian scenario is concerned most of the Hindu and Muslim females uses lead/arsenic based cosmetics.Methods: For the qualitative/quantitative estimation to detect heavy metals such as arsenic and lead in cosmetics, 20 different types of cosmetics were purchased from local market, labelled and analysed by qualitative test for heavy metals method and ICP-AES Analysis of cosmetics method.Results: A questionnaire was framed out in English and analysis showed that students had an adverse effect while using cosmetic products. Preliminary analysis of some samples gave positive results and for confirmation these samples were sent to IIT Bombay for ICP-AES analysis. Some of the samples showed variable level of heavy metals such as lead and arsenic. Highest concentration of lead and arsenic was found in Surma followed by Sindoor, lip balm and Kajal.Conclusions: Heavy metals are one of the major contaminant in our eco system. Apart from this a number of cosmetic products also contain the same. Chronic use of this kind of cosmetic products will leads heavy metal toxicity

Observation of transient superconductivity at the LaAlO3_3/SrTiO3_3 interface

We report the observation of a magnetic field assisted transient superconducting state in the two dimensional electron gas existing at the interface of LaAlO$_3$/SrTiO$_3$ heterostructures. This metastable state depends critically on the density of charge carriers in the system. It appears concomitantly with a Lifshitz transition as a consequence of the interplay between ferromagnetism and superconductivity and the finite relaxation time of the in-plane magnetization. Our results clearly demonstrate the inherently metastable nature of the superconducting state competing with a magnetic order in these systems. The co-existence of superconductivity and ferromagnetism in the conducting electronic layer formed at the interface of insulating oxides has thrown up several intriguing and as yet unanswered questions. An open question in this field is the energetics of the interplay between these two competing orders and the present observation goes a long way in understanding the underlying mechanism.Comment: 11 pages, 14 figure

CLINICAL OUTCOMES OF USE OF HYDROXYCHLOROQUINE IN PARADOXICAL TUBERCULOSIS-IMMUNE RECONSTITUTION INFLAMMATORY SYNDROME IN HIV-INFECTED PATIENTS.

 Objective: Immune reconstitution inflammatory syndrome (IRIS) is an inflammatory reaction in HIV-infected patients after initiation of antiretroviral therapy (ART) resulting from restored immunity to specific infectious or non-infectious antigens. The most common condition where IRIS has been reported is tuberculosis (TB). Various mechanisms have been proposed and studied to account for the immune regulatory role of hydroxychloroquine (HCQ). This study is done to identify clinical outcome in HIV-TB patients with IRIS after given with HCQ.Methods: An uncontrolled longitudinal study was conducted among HIV-infected patients with TB initiated on ART and developed IRIS between July 2013 and June 2015 in a South Indian HIV care hospital.Results: A total of 40 patients have developed IRIS with mean age of 35.87 years and 77.5 % of them were males. At the time of IRIS occurrence, the mean body mass index was found to be 19.17 kg/m2 and CD4 count was 200 cells/mm3. The time duration took to get improvement in majority of the patients was 4–12 weeks.Conclusion: There was definite improvement seen in patients who received HCQ in TB-IRIS condition

Magnetic, magneto-thermal and magneto-transport properties in SmMn2Si2-xGex compounds

The effect of Ge substitution for Si in SmMMn2Si2-xGex compounds has been studied. The Sm ordering temperature is found to be much larger in the compound with x=2, as compared to the compounds with x=0 and 1. The increase in the intra layer Mn-Mn distance is found to be responsible for this increase. Among these three compounds, SmMn2Ge2 is found to show re-entrant ferromagnetism at low temperatures. The magnetic contribution to the heat capacity has been found in all the three compounds. The splitting of the ground state multiplet has been estimated by fitting the magnetic part of the heat capacity data using the Schottky formula. The isothermal magnetic entropy change is found to remain the same for x=0 and 1, but decrease in the compound with x=2, though the nature of magnetic transition changes from second order to first order, as x is increased from 0 to 2. The electrical resistivity increases with Ge concentration. The excess resistivity in the antiferromagnetic region has been calculated

Three years follow up of open medial sub-talar dislocation of ankle: a case report

Open medial sub-talar dislocation is a rare lesion in traumatology. Even after early treatment, these injuries progress to sub-talar arthrosis. Here we describe a case of 24 years male with open type 3B medial sub-talar dislocation with calcaneum sustentaculum tali fracture following road traffic accident. He underwent emergency wound debridement and internal fixation with K-wires and VAC application. He was on regular monthly follow-up for 6 months and then 6 monthly follow-ups till date. K-wires were removed 8 weeks after surgery and gradual range of movement was started. Partial weight bearing was started at 12 weeks. He was pain free and returned to work after 8 months. At 3 years follow up patient is able to walk without pain, normal painless ROM at ankle. To the best of our knowledge, long term follow-up of patient with these lesions is not reported. Here we present a case with 3 years follow-up showing good results in patient with open sub-talar dislocation after early management with internal fixation with K-wires and VAC dressing

Effect of Ge substitution for Si on the anomalous magnetocaloric and magnetoresistance properties of GdMn2Si2 compounds

The effect of Ge substitution on the magnetization, heat capacity, magnetocaloric effect and magnetoresistance of GdMn2Si2-xGex (x=0, 1, and 2) compounds has been studied. The magnetic transition associated with the Gd ordering is found to change from second order to first order on Ge substitution. Magnetic contributions to the total heat capacity and the entropy have been estimated. Magnetocaloric effect has been calculated in terms of adiabatic temperature change (deltaTad) as well as isothermal magnetic entropy change (deltaSM) using the heat capacity data. The temperature dependence of the magnetocaloric effect in all the three compounds have shown broad peaks. The maximum values of deltaSM and deltaTad for GdMn2Ge2 are found to be 5.9 J/kgK and 1.2 K, respectively. The magnetoresistance is found to be very large and positive with a maximum value of about 22% in the case of GdMn2Ge2. In the other two compounds also, the magnetoresistance is predominantly positive, except in the vicinity of the Gd ordering temperature. The anomalous nature of the magnetocaloric effect and the magnetoresistance has been attributed to the canted magnetic structure of these compounds