Journal of Pharmaceutical Research International, 2021
Topical drug administration is a localized drug delivery system anywhere in the body through opht... more Topical drug administration is a localized drug delivery system anywhere in the body through ophthalmic, rectal, vaginal and skin as topical routes. Skin is one of the most readily accessible organs on human body for topical administration and is main route of topical drug delivery system. There are various skin infections caused by fungus. An antifungal medication is a pharmaceutical fungicide used to treat mycoses such as athlete’s foot ringworm, candidiasis. Antifungal works by exploiting differences between mammalian and fungal cells to kill the fungal organism without dangerous effect on host. Itraconazole (ITZ) is commonly used in the treatment of fungal infections. It has low bioavailability (55%) because of low aqueous solubility and first pass effect. Hence we attempted to develop Itraconazole-loaded invasomes hydrogel. ITZ-loaded invasomes were prepared by conventional thin layer evaporation technique using Phospholipon 90H, terpene (Limonene) and ethanol. The optimized IT...
Background We conducted this study to identify the influence of prolonged use of hydroxychloroqui... more Background We conducted this study to identify the influence of prolonged use of hydroxychloroquine(HCQ), glucocorticoids (GC) and other immunosuppressants (IS) on occurrence and outcome of COVID-19 in patients with autoimmune rheumatic diseases (AIRDs). Methods This was a prospective, multicenter, non-interventional longitudinal study across 15 specialist rheumatology centers. Consecutive AIRD patients on treatment with immunosuppressants were recruited and followed up longitudinally to assess parameters contributing to development of COVID-19 and its outcome. Results COVID-19 occurred in 314(3.45%) of 9212 AIRD patients during a median follow up of 177 (IQR 129,219) days. Long term HCQ use had no major impact on the occurrence or the outcome of COVID-19. Glucocorticoids in moderate dose (7.5-20mg/day) conferred higher risk (RR = 1.72) of infection. Among the IS, Mycophenolate mofetil (MMF), Cyclophosphamide (CYC) and Rituximab (RTX) use was higher in patients with COVID 19. Howeve...
SnSe/SnSe2 has diverse applications like solar cells, photodetectors, memory devices, Li and Na-i... more SnSe/SnSe2 has diverse applications like solar cells, photodetectors, memory devices, Li and Na-ion batteries, gas sensors, photocatalysis, supercapacitors, topological insulators, resistive switching devices due to its optimal band gap.
The SARS-CoV-2 virus is the causative agent of the global COVID-19 infectious disease outbreak, w... more The SARS-CoV-2 virus is the causative agent of the global COVID-19 infectious disease outbreak, which can lead to acute respiratory distress syndrome (ARDS). However, it is still unclear how the virus interferes with immune cell and metabolic functions in the human body. In this study, we investigated the immune response in acute or convalescent COVID19 patients. We characterized the peripheral blood mononuclear cells (PBMCs) using flow cytometry and found that CD8+ T cells were significantly subsided in moderate COVID-19 and convalescent patients. Furthermore, characterization of CD8+ T cells suggested that patients with a mild and moderate course of the COVID-19 disease and convalescent patients have significantly diminished expression of both perforin and granzyme A in CD8+ T cells. Using 1H-NMR spectroscopy, we characterized the metabolic status of their autologous PBMCs. We found that fructose, lactate and taurine levels were elevated in infected (mild and moderate) patients co...
We demonstrate that the surface of the honeycomb lattice iridate Na2IrO3 is extremely tunable by ... more We demonstrate that the surface of the honeycomb lattice iridate Na2IrO3 is extremely tunable by plasma etching. We have succeeded in turning the surface of Na2IrO3 metallic by Ar plasma etching which leads to the removal of Na from the surface. The surface structure does not change in this process as revealed by grazing incidence small angle x-ray scattering (GISAXS). The sheet resistance Rs can be reduced by several orders of magnitude by varying the etching duration. Temperature dependent Rs(T ) for the metallic samples show signatures of spin or charge density wave transitions with abrupt changes in Rs. Thermal hysteresis between cooling and warming measurements across the transition indicates a first order transition. For the most metallic sample Rs(T ) data at low temperatures follow a T 2 behaviour suggesting normal Fermi liquid behaviour.
Background: The widely expressed protein chorein fosters activation of the phosphoinositide 3 kin... more Background: The widely expressed protein chorein fosters activation of the phosphoinositide 3 kinase (PI3K) pathway thus supporting cell survival. Loss of function mutations of the chorein encoding gene VPS13A (vacuolar protein sorting-associated protein 13A) causes chorea-acanthocytosis (ChAc), a neurodegenerative disorder paralleled by deformations of erythrocytes. In mice, genetic knockout of chorein leads to enhanced neuronal apoptosis. PI3K dependent signalling upregulates Orai1, a pore forming channel protein accomplishing store operated Ca2+ entry (SOCE). Increased Orai1 expression and SOCE have been shown to confer survival of tumor cells. SOCE could be up-regulated by lithium. The present study explored, whether SOCE and/or apoptosis are altered in ChAc fibroblasts and could be modified by lithium treatment. Methods: Fibroblasts were isolated from ChAc patients and age-matched healthy volunteers. Cytosolic Ca2+ activity ([Ca2+]i) was estimated from Fura-2-fluorescence, SOCE...
The mycobacterial mel2 locus (mycobacterial enhanced infection locus, Rv1936-1941 is Mycobacteriu... more The mycobacterial mel2 locus (mycobacterial enhanced infection locus, Rv1936-1941 is Mycobacterium marinum and M. tuberculosis specific, which can withstand reactive oxygen species (ROS) and reactive nitrogen species (RNS) induced stress. A library of over a million compounds was screened using in silico virtual ligand screening (VLS) to identify inhibitors against the modeled structure of MelF protein expressed by melF of mel2 locus so that M. marinum's ability to withstand ROS/RNS stress could be reduced. The top ranked 1000 compounds were further screened to identify 178 compounds to maximize the scaffold diversity by manually evaluating the interaction of each compound with the target site. M. marinum melF was cloned, expressed and purified as maltose binding protein (MBP)tagged recombinant protein in Escherichia coli. After establishing the flavin dependent oxidoreductase activity of MelF (~84 kDa), the inhibitors were screened for the inhibition of enzyme activity of whole cell lysate (WCL) and the purified MelF. Amongst these, 16 compounds could significantly inhibit the enzyme activity of purified MelF. For the six best inhibitory compounds, the minimal inhibitory concentration (MIC) was determined to be 3.4-19.4 μM and 13.5-38.8 μM for M. marinum and M. tuberculosis, respectively. Similarly, the minimal bactericidal concentration (MBC) was determined to be 6.8-38.8 μM and 27-38.8 μM against M. marinum and M. tuberculosis, respectively. One compound each in combination with isoniazid (INH) also showed synergistic inhibitory effect against M. marinum and M. tuberculosis with no cytotoxicity in HeLa cells. Interestingly, these inhibitors did not display any non-specific protein-structure destabilizing effect. Such inhibitors targeting the anti-ROS/RNS machinery may facilitate the efficient killing of replicating and nonreplicating mycobacteria inside the host cells.
Putative functions of the heterotrimeric G-protein subunit Gαi2-dependent signaling include ion c... more Putative functions of the heterotrimeric G-protein subunit Gαi2-dependent signaling include ion channel regulation, cell differentiation, proliferation and apoptosis. Erythrocytes may, similar to apoptosis of nucleated cells, undergo eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine (PS) exposure. Eryptosis may be triggered by increased cytosolic Ca(2+) activity and ceramide. In the present study, we show that Gαi2 is expressed in both murine and human erythrocytes and further examined the survival of erythrocytes drawn from Gαi2-deficient mice (Gαi2(-/-)) and corresponding wild-type mice (Gαi2(+/+)). Our data show that plasma erythropoietin levels, erythrocyte maturation markers, erythrocyte counts, hematocrit and hemoglobin concentration were similar in Gαi2(-/-) and Gαi2(+/+) mice but the mean corpuscular volume was significantly larger in Gαi2(-/-) mice. Spontaneous PS exposure of circulating Gαi2(-/-) erythrocytes was significantly ...
We report structure, electrical resistivity, magnetic susceptibility, isothermal magnetization an... more We report structure, electrical resistivity, magnetic susceptibility, isothermal magnetization and heat-capacity studies on polycrystalline samples of the intermetallic series RE 2 Ir 3 Ge 5 (RE = Y, La, Ce-Nd, Gd-Tm, Lu) from 1.5 to 300 K. We find that the compounds for RE = Y, La-Dy, crystallize in the tetragonal Ibam (U 2 Co 3 Si 5 type) structure whereas the compounds for RE= Er-Lu, crystallize in a new orthorhombic structure with a space group Pmmn. Samples of Ho 2 Ir 3 Ge 5 were always found to be multiphase. The compounds for RE = Y to Dy which adopt the Ibam type structure show a metallic resistivity whereas the compounds with RE = Er, Tm and Lu show an anomalous behavior in the resistivity with a semiconducting increase in ρ as we go down in temperature from 300 K. Interestingly we had earlier found a positive temperature coefficient of resistivity for the Yb sample in the same temperature range. We will compare this behavior with similar observations in the compounds RE 3 Ru 4 Ge 13 and REBiPt. La 2 Ir 3 Ge 5 and Y 2 Ir 3 Ge 5 show bulk superconductivity below 1.8 K and 2.5 K respectively. Our results confirm that Ce 2 Ir 3 Ge 5 shows a Kondo lattice behavior and undergoes antiferromagnetic ordering below 8.5 K. Most of the other compounds containing magnetic rare-earth elements undergo a single antiferromagnetic transition at low temperatures (T≤12 K) while Gd 2 Ir 3 Ge 5 , Dy 2 Ir 3 Ge 5 and Nd 2 Ir 3 Ge 5 show multiple transitions. The T N 's for most of the compounds 1 roughly scale with the de Gennes factor. which suggests that the primary mechanism of interaction leading to the magnetic ordering of the magnetic moments may be the RKKY interaction. The ordering temperature of 8.5 K for Ce 2 Ir 3 Ge 5 is anomalously large compared to the T N for Gd 2 Ir 3 Ge 5 which is about 12 K.There are signs of strong CEF influence on the measured properties for the series.
We have synthesized the novel material Na_2IrO_3 and studied its structure, transport, magnetic, ... more We have synthesized the novel material Na_2IrO_3 and studied its structure, transport, magnetic, and thermal properties using powder x-ray diffraction (PXRD), electrical resistivity, isothermal magnetization M versus magnetic field H, static \chi and dynamic \chi_ac magnetic susceptibility versus temperature T, and heat capacity C versus T measurements. Na_2IrO_3 crystallizes in the monoclinic C2/c (No. 15) structure which is made up
This study presented a potentially useful alternative approach to ascertain the presence of subcl... more This study presented a potentially useful alternative approach to ascertain the presence of subclinical and clinical mastitis in dairy cows using support vector machine (SVM) techniques. The proposed method detected mastitis in a cross-sectional representative sample of Holstein dairy cattle milked using an automatic milking system. The study used such suspected indicators of mastitis as lactation rank, milk yield, electrical conductivity, average milking duration, and control season as input data. The output variable was somatic cell counts obtained from milk samples collected monthly throughout the 15 months of the control period. Cattle were judged to be healthy or infected based on those somatic cell counts. This study undertook a detailed scrutiny of the SVM methodology, constructing and examining a model which showed 89% sensitivity, 92% specificity, and 50% error in mastitis detection.
Sr4Cr3O9 is the n = 2 member of a family of quasi-one-dimensional compounds An+2Tn+1O3n+3 (A = Ca... more Sr4Cr3O9 is the n = 2 member of a family of quasi-one-dimensional compounds An+2Tn+1O3n+3 (A = Ca, Sr, or Ba, T = transition metal, and n = 1 -∞) having a crystal structure which consists of chains of nT O6 octahedra alternated by one T O6 trigonal prism running along the caxis. The chains are arranged on a triangular lattice in the ab-plane. We report the synthesis, structure, magnetization M versus magnetic field H, magnetic susceptibility χ versus temperature T and specific heat C versus T measurements on sintered and arc-melted polycrystalline samples of Sr4Cr3O9. The χ data have a T depdendence which is typical of low-dimensional magnetic systems with dominant antiferromagnetic (AF) exchange interactions. Specifically, χ(T ) shows a broad maximum at Tmax ≈ 200 K for the sintered pellet and Tmax ≈ 265 K for the arc-melted sample, indicating the onset of short-range magnetic order. Below T = 15 K we observe 2 anomalies in the χ(T ) data for both samples suggesting the onset of long-range magnetic ordering. The corresponding anomalies in the C(T ) data however are weak indicating that only a small amount of the expected magnetic entropy is recovered at the magnetic transitions and that strong short-range AF order exists above these temperatures.
Magnetic susceptibility chi, isothermal magnetization M, resistivity rho, Hall effect, and heat c... more Magnetic susceptibility chi, isothermal magnetization M, resistivity rho, Hall effect, and heat capacity C measurements on EuRh2As2 reveal complex and unusual magnetic behavior. The chi(T) data gave a small Weiss temperature theta 12 K indicating predominantly ferromagnetic interactions between the Eu^2+ moments. Below T = 47 K, however chi(T) indicates that an antiferromagnetic transition occurs instead. The unusually high TN compared to theta (theta/TN 0.26) suggests novel physics. A metamagnetic transition is observed in the M versus H data at T < TN when H is applied in the ab plane. The metamagnetic field shows an unusual T dependence, decreasing slightly between T = 2 K and 30 K and increasing again on approaching TN before vanishing abruptly at TN. In zero field the rho(T) data indicate metallic behavior between 2 K and 300 K. However, at low temperatures T <=30 K, rho(T) increases dramatically in an applied field H and we observe a giant positive magnetoresistance of 9...
Combining thermodynamic measurements with theoretical density functional and thermodynamic calcul... more Combining thermodynamic measurements with theoretical density functional and thermodynamic calculations we demonstrate that the honeycomb lattice iridates A2IrO3 (A =Na, Li) are magnetically ordered Mott insulators where the magnetism of the effective spin-orbital S=1/2 moments can be captured by a Heisenberg-Kitaev (HK) model with Heisenberg interactions beyond nearest-neighbor exchange. Experimentally, we observe an increase of the Curie-Weiss temperature from θ ≈ -125 K for Na2IrO3 to θ ≈ -33 K for Li2IrO3, while the antiferromagnetic ordering temperature remains roughly the same TN ≈ 15 K for both materials. Using finite-temperature functional renormalization group calculations we show that this evolution of θ, TN , the frustration parameter f = θ/TN , and the zig-zag magnetic ordering structure suggested for both materials by density functional theory can be captured within this extended HK model. Combining our experimental and theoretical results, we estimate that Na2IrO3 is deep in the magnetically ordered regime of the HK model (α ≈ 0.25), while Li2IrO3 appears to be close to a spin-liquid regime (0.6 ≤ α ≤ 0.7).
We report a combined experimental and theoretical investigation of the magnetic structure of the ... more We report a combined experimental and theoretical investigation of the magnetic structure of the honeycomb lattice magnet Na2IrO3, a candidate for a realization of a gapless spin-liquid. Using resonant x-ray magnetic scattering at the Ir L3-edge, we find 3D long range antiferromagnetic order below TN =13.3 K. From the azimuthal dependence of the magnetic Bragg peak, the ordered moment is determined to be predominantly along the a-axis. Combining the experimental data with first principles calculations, we propose that the most likely spin structure is a "zig-zag" structure.
Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temp... more Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temperature T range from 10 K to 675 K. These measurements demonstrate that this compound exhibits collinear antiferromagnetic ordering below the Néel temperature TN = 625(1) K. The ordered moment µ = 3.88(4) µB/Mn at T = 10 K is oriented along the c axis and the magnetic structure is G-type, with all nearest-neighbor Mn moments antiferromagnetically aligned. The value of the ordered moment indicates that the oxidation state of Mn is Mn 2+ with a high spin S = 5/2. The T dependence of µ suggests that the magnetic transition is second-order in nature. In contrast to the closely related AFe2As2 (A = Ca, Sr, Ba, Eu) compounds, no structural distortion is observed in the magnetically ordered state of BaMn2As2. Our results indicate that while next-nearest-neighbor interactions are important in the AFe2As2 materials, nearest-neighbor interactions are dominant in BaMn2As2.
The spin dynamics of the two-dimensional ͑2D͒ triangular lattice antiferromagnets HCrO 2 , LiCrO ... more The spin dynamics of the two-dimensional ͑2D͒ triangular lattice antiferromagnets HCrO 2 , LiCrO 2 , and NaCrO 2 is investigated by electron spin resonance. In these oxides, on approaching the Néel temperature T N from above, the divergence of the temperature dependent linewidth is well described in terms of a Berezinskii-Kosterlitz-Thouless scenario due to magnetic vortex-antivortex pairing. A refined analysis suggests analogies to the melting scenario of a 2D triangular lattice described by Nelson, Halperin, and Young.
We have synthesized single crystals of Na2IrO3 and studied their structure, transport, magnetic, ... more We have synthesized single crystals of Na2IrO3 and studied their structure, transport, magnetic, and thermal properties using powder x-ray diffraction (PXRD), electrical resistivity, isothermal magnetization M versus magnetic field H, magnetic susceptibility χ versus temperature T , and heat capacity C versus T measurements. Na2IrO3 crystallizes in the monoclinic C2/c (No. 15) type structure which is made up of Na and NaIr2O6 layers alternately stacked along the c axis. The χ(T ) data show Curie-Weiss behavior at high T > 200 K with an effective moment µ eff = 1.82(1)µB indicating an effective spin S eff = 1/2 on the Ir 4+ moments. A large Weiss temperature θ = -116(3) K indicates substantial antiferromagnetic interactions between these S eff = 1/2, Ir 4+ moments. Sharp anomalies in χ(T ) and C(T ) data indicate that Na2IrO3 undergoes a transition into a long-range antiferromagnetically ordered state below TN = 15 K. The magnetic entropy at TN is only about 20% of what is expected for S eff = 1/2 moment ordering. The reduced entropy and the small ratio TN /θ ≈ 0.13 suggest geometrical magnetic frustration and/or low-dimensional magnetic interactions in Na2IrO3. In plane resistivity measurements show insulating behavior. This together with the local moment magnetism indicates that bulk Na2IrO3 is a Mott insulator.
Polycrystalline samples of the ternary rare-earth silicide compounds R 2 Ir 3 Si 5 ͑R =Y,La,Ce-Nd... more Polycrystalline samples of the ternary rare-earth silicide compounds R 2 Ir 3 Si 5 ͑R =Y,La,Ce-Nd,Gd-Tm͒ have been prepared and characterized using room temperature powder x-ray, magnetic susceptibility, electrical resistivity, and low-temperature ͑1.6-30 K͒ zero-field heat capacity measurements. All the compounds crystallize in the tetragonal U 2 Co 3 Si 5 type structure (space group Ibam). The effective moments estimated from Curie-Weiss fits to the high-temperature inverse susceptibility data suggest that Ir may carry an induced moment in these compounds. The systematics of the lattice parameters across the series suggest that Ce is trivalent in Ce 2 Ir 3 Si 5 , whereas the magnetic, transport, and heat capacity measurements reveal a nonmagnetic behavior for this compound, suggesting that this is a strongly hybridized compound similar to Ce 2 Rh 3 Si 5 . Pr 2 Ir 3 Si 5 also does not order down to 1.8 K. Large and prominent peaks at low temperatures in the susceptibility and heat capacity of the other magnetic rare-earth-containing compounds indicate bulk magnetic ordering of trivalent rare-earth moments in these compounds. The heat capacity data for Gd 2 Ir 3 Si 5 show three anomalies, one above and one below the main type antiferromagnetic transition peak at 11.8 K, while the data for Tb 2 Ir 3 Si 5 also suggest two transitions. Most of the compounds have transition temperatures which follow the de Gennes scaling. However, Nd 2 Ir 3 Si 5 and Tb 2 Ir 3 Si 5 have anomalously large transition temperatures compared to that expected by the de Gennes scaling. Large crystalline electric field effects are indicated by the reduced value of the magnetic entropy at 30 K, and this could be a possible reason for the deviation of the ordering temperature T N from the de Gennes factor. From the temperature dependence of the magnetic entropy we conclude that Nd
An antiferromagnetic transition is observed in single crystal EuRh2As2 at a high temperature TN =... more An antiferromagnetic transition is observed in single crystal EuRh2As2 at a high temperature TN = 47 K compared to the ferromagnetic Weiss temperature θ = 12 K. We show that this is, surprisingly, consistent with mean field theory. A first-order field-induced magnetic transition is observed at T < TN with an unusual temperature dependence of the transition field. A dramatic magnetic field-induced reduction of the electronic specific heat coefficient at 1.8-5.0 K by 38% at 9 T is observed. In addition, a strong positive magnetoresistance and a large change in the Hall coefficient occur below 25 K. Band structure calculations indicate that the Fermi energy lies on a steep edge of a narrow peak in the density of states.
Journal of Pharmaceutical Research International, 2021
Topical drug administration is a localized drug delivery system anywhere in the body through opht... more Topical drug administration is a localized drug delivery system anywhere in the body through ophthalmic, rectal, vaginal and skin as topical routes. Skin is one of the most readily accessible organs on human body for topical administration and is main route of topical drug delivery system. There are various skin infections caused by fungus. An antifungal medication is a pharmaceutical fungicide used to treat mycoses such as athlete’s foot ringworm, candidiasis. Antifungal works by exploiting differences between mammalian and fungal cells to kill the fungal organism without dangerous effect on host. Itraconazole (ITZ) is commonly used in the treatment of fungal infections. It has low bioavailability (55%) because of low aqueous solubility and first pass effect. Hence we attempted to develop Itraconazole-loaded invasomes hydrogel. ITZ-loaded invasomes were prepared by conventional thin layer evaporation technique using Phospholipon 90H, terpene (Limonene) and ethanol. The optimized IT...
Background We conducted this study to identify the influence of prolonged use of hydroxychloroqui... more Background We conducted this study to identify the influence of prolonged use of hydroxychloroquine(HCQ), glucocorticoids (GC) and other immunosuppressants (IS) on occurrence and outcome of COVID-19 in patients with autoimmune rheumatic diseases (AIRDs). Methods This was a prospective, multicenter, non-interventional longitudinal study across 15 specialist rheumatology centers. Consecutive AIRD patients on treatment with immunosuppressants were recruited and followed up longitudinally to assess parameters contributing to development of COVID-19 and its outcome. Results COVID-19 occurred in 314(3.45%) of 9212 AIRD patients during a median follow up of 177 (IQR 129,219) days. Long term HCQ use had no major impact on the occurrence or the outcome of COVID-19. Glucocorticoids in moderate dose (7.5-20mg/day) conferred higher risk (RR = 1.72) of infection. Among the IS, Mycophenolate mofetil (MMF), Cyclophosphamide (CYC) and Rituximab (RTX) use was higher in patients with COVID 19. Howeve...
SnSe/SnSe2 has diverse applications like solar cells, photodetectors, memory devices, Li and Na-i... more SnSe/SnSe2 has diverse applications like solar cells, photodetectors, memory devices, Li and Na-ion batteries, gas sensors, photocatalysis, supercapacitors, topological insulators, resistive switching devices due to its optimal band gap.
The SARS-CoV-2 virus is the causative agent of the global COVID-19 infectious disease outbreak, w... more The SARS-CoV-2 virus is the causative agent of the global COVID-19 infectious disease outbreak, which can lead to acute respiratory distress syndrome (ARDS). However, it is still unclear how the virus interferes with immune cell and metabolic functions in the human body. In this study, we investigated the immune response in acute or convalescent COVID19 patients. We characterized the peripheral blood mononuclear cells (PBMCs) using flow cytometry and found that CD8+ T cells were significantly subsided in moderate COVID-19 and convalescent patients. Furthermore, characterization of CD8+ T cells suggested that patients with a mild and moderate course of the COVID-19 disease and convalescent patients have significantly diminished expression of both perforin and granzyme A in CD8+ T cells. Using 1H-NMR spectroscopy, we characterized the metabolic status of their autologous PBMCs. We found that fructose, lactate and taurine levels were elevated in infected (mild and moderate) patients co...
We demonstrate that the surface of the honeycomb lattice iridate Na2IrO3 is extremely tunable by ... more We demonstrate that the surface of the honeycomb lattice iridate Na2IrO3 is extremely tunable by plasma etching. We have succeeded in turning the surface of Na2IrO3 metallic by Ar plasma etching which leads to the removal of Na from the surface. The surface structure does not change in this process as revealed by grazing incidence small angle x-ray scattering (GISAXS). The sheet resistance Rs can be reduced by several orders of magnitude by varying the etching duration. Temperature dependent Rs(T ) for the metallic samples show signatures of spin or charge density wave transitions with abrupt changes in Rs. Thermal hysteresis between cooling and warming measurements across the transition indicates a first order transition. For the most metallic sample Rs(T ) data at low temperatures follow a T 2 behaviour suggesting normal Fermi liquid behaviour.
Background: The widely expressed protein chorein fosters activation of the phosphoinositide 3 kin... more Background: The widely expressed protein chorein fosters activation of the phosphoinositide 3 kinase (PI3K) pathway thus supporting cell survival. Loss of function mutations of the chorein encoding gene VPS13A (vacuolar protein sorting-associated protein 13A) causes chorea-acanthocytosis (ChAc), a neurodegenerative disorder paralleled by deformations of erythrocytes. In mice, genetic knockout of chorein leads to enhanced neuronal apoptosis. PI3K dependent signalling upregulates Orai1, a pore forming channel protein accomplishing store operated Ca2+ entry (SOCE). Increased Orai1 expression and SOCE have been shown to confer survival of tumor cells. SOCE could be up-regulated by lithium. The present study explored, whether SOCE and/or apoptosis are altered in ChAc fibroblasts and could be modified by lithium treatment. Methods: Fibroblasts were isolated from ChAc patients and age-matched healthy volunteers. Cytosolic Ca2+ activity ([Ca2+]i) was estimated from Fura-2-fluorescence, SOCE...
The mycobacterial mel2 locus (mycobacterial enhanced infection locus, Rv1936-1941 is Mycobacteriu... more The mycobacterial mel2 locus (mycobacterial enhanced infection locus, Rv1936-1941 is Mycobacterium marinum and M. tuberculosis specific, which can withstand reactive oxygen species (ROS) and reactive nitrogen species (RNS) induced stress. A library of over a million compounds was screened using in silico virtual ligand screening (VLS) to identify inhibitors against the modeled structure of MelF protein expressed by melF of mel2 locus so that M. marinum's ability to withstand ROS/RNS stress could be reduced. The top ranked 1000 compounds were further screened to identify 178 compounds to maximize the scaffold diversity by manually evaluating the interaction of each compound with the target site. M. marinum melF was cloned, expressed and purified as maltose binding protein (MBP)tagged recombinant protein in Escherichia coli. After establishing the flavin dependent oxidoreductase activity of MelF (~84 kDa), the inhibitors were screened for the inhibition of enzyme activity of whole cell lysate (WCL) and the purified MelF. Amongst these, 16 compounds could significantly inhibit the enzyme activity of purified MelF. For the six best inhibitory compounds, the minimal inhibitory concentration (MIC) was determined to be 3.4-19.4 μM and 13.5-38.8 μM for M. marinum and M. tuberculosis, respectively. Similarly, the minimal bactericidal concentration (MBC) was determined to be 6.8-38.8 μM and 27-38.8 μM against M. marinum and M. tuberculosis, respectively. One compound each in combination with isoniazid (INH) also showed synergistic inhibitory effect against M. marinum and M. tuberculosis with no cytotoxicity in HeLa cells. Interestingly, these inhibitors did not display any non-specific protein-structure destabilizing effect. Such inhibitors targeting the anti-ROS/RNS machinery may facilitate the efficient killing of replicating and nonreplicating mycobacteria inside the host cells.
Putative functions of the heterotrimeric G-protein subunit Gαi2-dependent signaling include ion c... more Putative functions of the heterotrimeric G-protein subunit Gαi2-dependent signaling include ion channel regulation, cell differentiation, proliferation and apoptosis. Erythrocytes may, similar to apoptosis of nucleated cells, undergo eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine (PS) exposure. Eryptosis may be triggered by increased cytosolic Ca(2+) activity and ceramide. In the present study, we show that Gαi2 is expressed in both murine and human erythrocytes and further examined the survival of erythrocytes drawn from Gαi2-deficient mice (Gαi2(-/-)) and corresponding wild-type mice (Gαi2(+/+)). Our data show that plasma erythropoietin levels, erythrocyte maturation markers, erythrocyte counts, hematocrit and hemoglobin concentration were similar in Gαi2(-/-) and Gαi2(+/+) mice but the mean corpuscular volume was significantly larger in Gαi2(-/-) mice. Spontaneous PS exposure of circulating Gαi2(-/-) erythrocytes was significantly ...
We report structure, electrical resistivity, magnetic susceptibility, isothermal magnetization an... more We report structure, electrical resistivity, magnetic susceptibility, isothermal magnetization and heat-capacity studies on polycrystalline samples of the intermetallic series RE 2 Ir 3 Ge 5 (RE = Y, La, Ce-Nd, Gd-Tm, Lu) from 1.5 to 300 K. We find that the compounds for RE = Y, La-Dy, crystallize in the tetragonal Ibam (U 2 Co 3 Si 5 type) structure whereas the compounds for RE= Er-Lu, crystallize in a new orthorhombic structure with a space group Pmmn. Samples of Ho 2 Ir 3 Ge 5 were always found to be multiphase. The compounds for RE = Y to Dy which adopt the Ibam type structure show a metallic resistivity whereas the compounds with RE = Er, Tm and Lu show an anomalous behavior in the resistivity with a semiconducting increase in ρ as we go down in temperature from 300 K. Interestingly we had earlier found a positive temperature coefficient of resistivity for the Yb sample in the same temperature range. We will compare this behavior with similar observations in the compounds RE 3 Ru 4 Ge 13 and REBiPt. La 2 Ir 3 Ge 5 and Y 2 Ir 3 Ge 5 show bulk superconductivity below 1.8 K and 2.5 K respectively. Our results confirm that Ce 2 Ir 3 Ge 5 shows a Kondo lattice behavior and undergoes antiferromagnetic ordering below 8.5 K. Most of the other compounds containing magnetic rare-earth elements undergo a single antiferromagnetic transition at low temperatures (T≤12 K) while Gd 2 Ir 3 Ge 5 , Dy 2 Ir 3 Ge 5 and Nd 2 Ir 3 Ge 5 show multiple transitions. The T N 's for most of the compounds 1 roughly scale with the de Gennes factor. which suggests that the primary mechanism of interaction leading to the magnetic ordering of the magnetic moments may be the RKKY interaction. The ordering temperature of 8.5 K for Ce 2 Ir 3 Ge 5 is anomalously large compared to the T N for Gd 2 Ir 3 Ge 5 which is about 12 K.There are signs of strong CEF influence on the measured properties for the series.
We have synthesized the novel material Na_2IrO_3 and studied its structure, transport, magnetic, ... more We have synthesized the novel material Na_2IrO_3 and studied its structure, transport, magnetic, and thermal properties using powder x-ray diffraction (PXRD), electrical resistivity, isothermal magnetization M versus magnetic field H, static \chi and dynamic \chi_ac magnetic susceptibility versus temperature T, and heat capacity C versus T measurements. Na_2IrO_3 crystallizes in the monoclinic C2/c (No. 15) structure which is made up
This study presented a potentially useful alternative approach to ascertain the presence of subcl... more This study presented a potentially useful alternative approach to ascertain the presence of subclinical and clinical mastitis in dairy cows using support vector machine (SVM) techniques. The proposed method detected mastitis in a cross-sectional representative sample of Holstein dairy cattle milked using an automatic milking system. The study used such suspected indicators of mastitis as lactation rank, milk yield, electrical conductivity, average milking duration, and control season as input data. The output variable was somatic cell counts obtained from milk samples collected monthly throughout the 15 months of the control period. Cattle were judged to be healthy or infected based on those somatic cell counts. This study undertook a detailed scrutiny of the SVM methodology, constructing and examining a model which showed 89% sensitivity, 92% specificity, and 50% error in mastitis detection.
Sr4Cr3O9 is the n = 2 member of a family of quasi-one-dimensional compounds An+2Tn+1O3n+3 (A = Ca... more Sr4Cr3O9 is the n = 2 member of a family of quasi-one-dimensional compounds An+2Tn+1O3n+3 (A = Ca, Sr, or Ba, T = transition metal, and n = 1 -∞) having a crystal structure which consists of chains of nT O6 octahedra alternated by one T O6 trigonal prism running along the caxis. The chains are arranged on a triangular lattice in the ab-plane. We report the synthesis, structure, magnetization M versus magnetic field H, magnetic susceptibility χ versus temperature T and specific heat C versus T measurements on sintered and arc-melted polycrystalline samples of Sr4Cr3O9. The χ data have a T depdendence which is typical of low-dimensional magnetic systems with dominant antiferromagnetic (AF) exchange interactions. Specifically, χ(T ) shows a broad maximum at Tmax ≈ 200 K for the sintered pellet and Tmax ≈ 265 K for the arc-melted sample, indicating the onset of short-range magnetic order. Below T = 15 K we observe 2 anomalies in the χ(T ) data for both samples suggesting the onset of long-range magnetic ordering. The corresponding anomalies in the C(T ) data however are weak indicating that only a small amount of the expected magnetic entropy is recovered at the magnetic transitions and that strong short-range AF order exists above these temperatures.
Magnetic susceptibility chi, isothermal magnetization M, resistivity rho, Hall effect, and heat c... more Magnetic susceptibility chi, isothermal magnetization M, resistivity rho, Hall effect, and heat capacity C measurements on EuRh2As2 reveal complex and unusual magnetic behavior. The chi(T) data gave a small Weiss temperature theta 12 K indicating predominantly ferromagnetic interactions between the Eu^2+ moments. Below T = 47 K, however chi(T) indicates that an antiferromagnetic transition occurs instead. The unusually high TN compared to theta (theta/TN 0.26) suggests novel physics. A metamagnetic transition is observed in the M versus H data at T < TN when H is applied in the ab plane. The metamagnetic field shows an unusual T dependence, decreasing slightly between T = 2 K and 30 K and increasing again on approaching TN before vanishing abruptly at TN. In zero field the rho(T) data indicate metallic behavior between 2 K and 300 K. However, at low temperatures T <=30 K, rho(T) increases dramatically in an applied field H and we observe a giant positive magnetoresistance of 9...
Combining thermodynamic measurements with theoretical density functional and thermodynamic calcul... more Combining thermodynamic measurements with theoretical density functional and thermodynamic calculations we demonstrate that the honeycomb lattice iridates A2IrO3 (A =Na, Li) are magnetically ordered Mott insulators where the magnetism of the effective spin-orbital S=1/2 moments can be captured by a Heisenberg-Kitaev (HK) model with Heisenberg interactions beyond nearest-neighbor exchange. Experimentally, we observe an increase of the Curie-Weiss temperature from θ ≈ -125 K for Na2IrO3 to θ ≈ -33 K for Li2IrO3, while the antiferromagnetic ordering temperature remains roughly the same TN ≈ 15 K for both materials. Using finite-temperature functional renormalization group calculations we show that this evolution of θ, TN , the frustration parameter f = θ/TN , and the zig-zag magnetic ordering structure suggested for both materials by density functional theory can be captured within this extended HK model. Combining our experimental and theoretical results, we estimate that Na2IrO3 is deep in the magnetically ordered regime of the HK model (α ≈ 0.25), while Li2IrO3 appears to be close to a spin-liquid regime (0.6 ≤ α ≤ 0.7).
We report a combined experimental and theoretical investigation of the magnetic structure of the ... more We report a combined experimental and theoretical investigation of the magnetic structure of the honeycomb lattice magnet Na2IrO3, a candidate for a realization of a gapless spin-liquid. Using resonant x-ray magnetic scattering at the Ir L3-edge, we find 3D long range antiferromagnetic order below TN =13.3 K. From the azimuthal dependence of the magnetic Bragg peak, the ordered moment is determined to be predominantly along the a-axis. Combining the experimental data with first principles calculations, we propose that the most likely spin structure is a "zig-zag" structure.
Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temp... more Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temperature T range from 10 K to 675 K. These measurements demonstrate that this compound exhibits collinear antiferromagnetic ordering below the Néel temperature TN = 625(1) K. The ordered moment µ = 3.88(4) µB/Mn at T = 10 K is oriented along the c axis and the magnetic structure is G-type, with all nearest-neighbor Mn moments antiferromagnetically aligned. The value of the ordered moment indicates that the oxidation state of Mn is Mn 2+ with a high spin S = 5/2. The T dependence of µ suggests that the magnetic transition is second-order in nature. In contrast to the closely related AFe2As2 (A = Ca, Sr, Ba, Eu) compounds, no structural distortion is observed in the magnetically ordered state of BaMn2As2. Our results indicate that while next-nearest-neighbor interactions are important in the AFe2As2 materials, nearest-neighbor interactions are dominant in BaMn2As2.
The spin dynamics of the two-dimensional ͑2D͒ triangular lattice antiferromagnets HCrO 2 , LiCrO ... more The spin dynamics of the two-dimensional ͑2D͒ triangular lattice antiferromagnets HCrO 2 , LiCrO 2 , and NaCrO 2 is investigated by electron spin resonance. In these oxides, on approaching the Néel temperature T N from above, the divergence of the temperature dependent linewidth is well described in terms of a Berezinskii-Kosterlitz-Thouless scenario due to magnetic vortex-antivortex pairing. A refined analysis suggests analogies to the melting scenario of a 2D triangular lattice described by Nelson, Halperin, and Young.
We have synthesized single crystals of Na2IrO3 and studied their structure, transport, magnetic, ... more We have synthesized single crystals of Na2IrO3 and studied their structure, transport, magnetic, and thermal properties using powder x-ray diffraction (PXRD), electrical resistivity, isothermal magnetization M versus magnetic field H, magnetic susceptibility χ versus temperature T , and heat capacity C versus T measurements. Na2IrO3 crystallizes in the monoclinic C2/c (No. 15) type structure which is made up of Na and NaIr2O6 layers alternately stacked along the c axis. The χ(T ) data show Curie-Weiss behavior at high T > 200 K with an effective moment µ eff = 1.82(1)µB indicating an effective spin S eff = 1/2 on the Ir 4+ moments. A large Weiss temperature θ = -116(3) K indicates substantial antiferromagnetic interactions between these S eff = 1/2, Ir 4+ moments. Sharp anomalies in χ(T ) and C(T ) data indicate that Na2IrO3 undergoes a transition into a long-range antiferromagnetically ordered state below TN = 15 K. The magnetic entropy at TN is only about 20% of what is expected for S eff = 1/2 moment ordering. The reduced entropy and the small ratio TN /θ ≈ 0.13 suggest geometrical magnetic frustration and/or low-dimensional magnetic interactions in Na2IrO3. In plane resistivity measurements show insulating behavior. This together with the local moment magnetism indicates that bulk Na2IrO3 is a Mott insulator.
Polycrystalline samples of the ternary rare-earth silicide compounds R 2 Ir 3 Si 5 ͑R =Y,La,Ce-Nd... more Polycrystalline samples of the ternary rare-earth silicide compounds R 2 Ir 3 Si 5 ͑R =Y,La,Ce-Nd,Gd-Tm͒ have been prepared and characterized using room temperature powder x-ray, magnetic susceptibility, electrical resistivity, and low-temperature ͑1.6-30 K͒ zero-field heat capacity measurements. All the compounds crystallize in the tetragonal U 2 Co 3 Si 5 type structure (space group Ibam). The effective moments estimated from Curie-Weiss fits to the high-temperature inverse susceptibility data suggest that Ir may carry an induced moment in these compounds. The systematics of the lattice parameters across the series suggest that Ce is trivalent in Ce 2 Ir 3 Si 5 , whereas the magnetic, transport, and heat capacity measurements reveal a nonmagnetic behavior for this compound, suggesting that this is a strongly hybridized compound similar to Ce 2 Rh 3 Si 5 . Pr 2 Ir 3 Si 5 also does not order down to 1.8 K. Large and prominent peaks at low temperatures in the susceptibility and heat capacity of the other magnetic rare-earth-containing compounds indicate bulk magnetic ordering of trivalent rare-earth moments in these compounds. The heat capacity data for Gd 2 Ir 3 Si 5 show three anomalies, one above and one below the main type antiferromagnetic transition peak at 11.8 K, while the data for Tb 2 Ir 3 Si 5 also suggest two transitions. Most of the compounds have transition temperatures which follow the de Gennes scaling. However, Nd 2 Ir 3 Si 5 and Tb 2 Ir 3 Si 5 have anomalously large transition temperatures compared to that expected by the de Gennes scaling. Large crystalline electric field effects are indicated by the reduced value of the magnetic entropy at 30 K, and this could be a possible reason for the deviation of the ordering temperature T N from the de Gennes factor. From the temperature dependence of the magnetic entropy we conclude that Nd
An antiferromagnetic transition is observed in single crystal EuRh2As2 at a high temperature TN =... more An antiferromagnetic transition is observed in single crystal EuRh2As2 at a high temperature TN = 47 K compared to the ferromagnetic Weiss temperature θ = 12 K. We show that this is, surprisingly, consistent with mean field theory. A first-order field-induced magnetic transition is observed at T < TN with an unusual temperature dependence of the transition field. A dramatic magnetic field-induced reduction of the electronic specific heat coefficient at 1.8-5.0 K by 38% at 9 T is observed. In addition, a strong positive magnetoresistance and a large change in the Hall coefficient occur below 25 K. Band structure calculations indicate that the Fermi energy lies on a steep edge of a narrow peak in the density of states.
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Papers by Yogesh Singh