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Regioselective Sulfenylation of alpha `-CH3 or alpha `-CH2 Groups of alpha,beta-Unsaturated Ketones with Heterocyclic Thiols
No full textA rare regioselective sulfenylation of alpha'-CH3 or alpha'-CH2 bonds adjacent to alpha,beta-unsaturated ketones using dimethyl sulfoxide as an oxidant and a substoichiometric amount of aq HI as an additive is described. This methodology employs a strong acid such as aq HI or iodine and exhibits a high regioselectivity without undergoing conjugate addition, which is difficult to achieve under the cross dehydrogenative coupling method
Forwarding in Heterogeneous Mobile Opportunistic Networks
No full textDue to intermittent connectivity among nodes in mobile opportunistic networks, the direct packet delivery strategy often experiences large delays. To alleviate this problem, nodes often pass a copy of their message to relay nodes, which in turn could deliver it to the destination. In this setting, we consider the problem of relay selection that minimizes the mean delivery delay. Applying ideas from a renewal theory, we derive a closed-form expression for the mean delivery delay in a heterogeneous network under any probabilistic two-hop relay selection policy. Utilizing this expression, a policy that assures the least mean delivery delay can be obtained as a solution of a linear program (the time complexity of O(n(3))). However, exploiting the structure of the mean delay minimization problem, we compute an optimal solution using an algorithm with linearithmic (O(n log n)) time complexity
Enhanced spin wave propagation in magnonic rings by bias field modulation
No full textWe simulate the spin wave (SW) dynamics in ring structures and obtain the omega - k dispersion relations corresponding to the output waveguide. Different bias field configurations affect the transfer of SW power from one arm of the structure to the other arm. To this end, we showthat circular or radial bias fields are more suitable for energy transfer across the ring than the conventional horizontal bias field H-x. The SW dispersion shows that modes excited, when the bias field is along the ring radius, are almost 10 dB higher in power when compared to the modal power in the case of H-x. This is also corroborated by the SW energy density in the receiving stub. (c) 2017 Author(s)
Same but not alike: Structure, flexibility and energetics of domains in multi-domain proteins are influenced by the presence of other domains
No full textThe majority of the proteins encoded in the genomes of eukaryotes contain more than one domain. Reasons for high prevalence of multi-domain proteins in various organisms have been attributed to higher stability and functional and folding advantages over single-domain proteins. Despite these advantages, many proteins are composed of only one domain while their homologous domains are part of multi-domain proteins. In the study presented here, differences in the properties of protein domains in single-domain and multi-domain systems and their influence on functions are discussed. We studied 20 pairs of identical protein domains, which were crystallized in two forms (a) tethered to other proteins domains and (b) tethered to fewer protein domains than (a) or not tethered to any protein domain. Results suggest that tethering of domains in multi-domain proteins influences the structural, dynamic and energetic properties of the constituent protein domains. 50% of the protein domain pairs show significant structural deviations while 90% of the protein domain pairs show differences in dynamics and 12% of the residues show differences in the energetics. To gain further insights on the influence of tethering on the function of the domains, 4 pairs of homologous protein domains, where one of them is a full-length single-domain protein and the other protein domain is a part of a multi-domain protein, were studied. Analyses showed that identical and structurally equivalent functional residues show differential dynamics in homologous protein domains; though comparable dynamics between in-silico generated chimera protein and multi-domain proteins were observed. From these observations, the differences observed in the functions of homologous proteins could be attributed to the presence of tethered domain. Overall, we conclude that tethered domains in multidomain proteins not only provide stability or folding advantages but also influence pathways resulting in differences in function or regulatory properties
JMJD6 induces HOTAIR, an oncogenic lincRNA, by physically interacting with its proximal promoter
No full textUsing microarray analysis, we found that HOX transcript antisense intergenic RNA (HOTAIR) is up-regulated by Jumonji domain containing-6 (JMJD6), a bifunctional lysyl hydroxylase and arginine demethylase. In breast cancer, both JMJD6 and HOTAIR RNAs increase tumor growth and associate with poor prognosis but no molecular relationship between them is known. We show that overexpression of JMJD6 increased HOTAIR expression and JMJD6 siRNAs suppressed it in ER+ MCF-7, triple negative MDA-MB-231 and non-breast cancer HEK 293 cells. Therefore, JMJD6 regulates HOTAIR independent of ER status. Using various deletion constructs spanning (-1874 to +50) of the HOTAIR promoter, we identified pHP216 (-216 to +50 bp) as the smallest construct that retained maximal JMJD6 responsiveness. In ChIP assays, JMJD6 bound this region suggesting that JMJD6 may be directly recruited to the HOTAIR promoter. Mutant JMJD6H187A that is devoid of enzymatic activity could bind this site but failed to induce transcription. ChIP and electromobility shift assays identified a JMJD6 interaction region from (-123 to -103 bp) within the HOTAIR promoter. In tumor samples but not normal breast tissue, the expression of JMJD6 linearly correlated with HOTAIR suggesting that JMJD6-mediated up-regulation may occur specifically in tumors. Further, concurrent high expression of both genes correlated with poor survival when individual expression of either gene showed no significant association in TCGA datasets. We propose that high JMJD6 expression may achieve higher levels of HOTAIR in breast tumors. Further, since high levels of HOTAIR promote metastasis and death, blocking JMJD6 may be useful in preventing such events
SIRT6 deacetylase transcriptionally regulates glucose metabolism in heart
No full textSirtuins are a family of enzymes, which govern a number of cellular processes essential for maintaining physiological balance. SIRT6, a nuclear sirtuin, is implicated in the development of metabolic disorders. The role of SIRT6 in regulation of cardiac metabolism is unexplored. Although glucose is not the primary energy source of heart, defects in glucose oxidation have been linked to heart failure. SIRT6(+/-) mice hearts exhibit increased inhibitory phosphorylation of PDH subunit E1. SIRT6 deficiency enhances FoxO1 nuclear localization that results in increased expression of PDK4. We show that SIRT6 transcriptionally regulates the expression of PDK4 by binding to its promoter. SIRT6(+/-) hearts show accumulation of lactate, indicating compromised mitochondrial oxidation. SIRT6 deficiency results in decreased oxygen consumption rate and concomitantly lesser ATP production. Mechanistically, SIRT6 deficiency leads to increased FoxO1-mediated transcription of PDK4. Our findings establish a novel link between SIRT6 and cardiac metabolism, suggesting a protective role of SIRT6 in maintaining cardiac homeostasis
Prediction of GWL with the help of GRACE TWS for unevenly spaced time series data in India : Analysis of comparative performances of SVR, ANN and LRM
No full textPrediction of Ground Water Level (GWL) is extremely important for sustainable use and management of ground water resource. The motivations for this work is to understand the relationship between Gravity Recovery and Climate Experiment (GRACE) derived terrestrial water change (Delta TWS) data and GWL, so that Delta TWS could be used as a proxy measurement for GWL. In our study, we have selected five observation wells from different geographic regions in India. The datasets are unevenly spaced time series data which restricts us from applying standard time series methodologies and therefore in order to model and predict GWL with the help of Delta TWS, we have built Linear Regression Model (LRM), Support Vector Regression (SVR) and Artificial Neural Network (ANN). Comparative performances of LRM, SVR and ANN have been evaluated with the help of correlation coefficient (rho) and Root Mean Square Error (RMSE) between the actual and fitted (for training dataset) or predicted (for test dataset) values of GWL. It has been observed in our study that Delta TWS is highly significant variable to model GWL and the amount of total variations in GWL that could be explained with the help of Delta TWS varies from 36.48% to 74.28% (0.3648 <= R-2 <= 0.7428). We have found that for the model GWL similar to Delta TWS, for both training and test dataset, performances of SVR and ANN are better than that of LRM in terms of rho and RMSE. It also has been found in our study that with the inclusion of meteorological variables along with Delta TWS as input parameters to model GWL, the performance of SVR improves and it performs better than ANN. These results imply that for modelling irregular time series GWL data, Delta TWS could be very useful. (C) 2018 Elsevier B.V. All rights reserved
Brownian motion under dynamic disorder: effects of memory on the decay of the non-Gaussianity parameter
No full textThe increasingly widespread occurrence in complex fluids of particle motion that is both Brownian and non-Gaussian has recently been found to be successfully modeled by a process (frequently referred to as `diffusing diffusivity') in which the white noise that governs Brownian diffusion is itself stochastically modulated by either Ornstein-Uhlenbeck dynamics or by two-state noise. But the model has so far not been able to account for an aspect of non-Gaussian Brownian motion that is also commonly observed: a non-monotonic decay of the parameter that quantifies the extent of deviation from Gaussian behavior. In this paper, we show that the inclusion of memory effects in the model-via a generalized Langevin equation-can rationalise this phenomenon
Correlation between structural and electrochemical properties of potassium doped strontium silicates for electrolyte application in intermediate temperature solid oxide fuel cells
No full textElectrolyte is the heart of the solid oxide fuel cell (SOFC), which can determine the working temperature. Currently, Yttria stabilized zirconia is used as electrolyte in commercial SOFCs, due to its high conductivity. The high working temperature (1073 K-1273 K) causes severe problems during SOFC design and operation. To reduce the working temperature of SOFCs to intermediate temperature (873 K-1073 K), here Sr1-XKXSiO3-delta (X = 0.00-0.20) solid solutions are synthesized by solid state reactions, characterized by different techniques. XRD patterns of Sr1-XKXSiO3-delta solid solutions can be indexed to monoclinic c2/c space group (15) structure. Si-29 solid state NMR spectra of SrSiO3 and Sr0.95K0.05O3-delta shows a sharp single peak at -83.5 ppm. In 10-20 mol% K-doped samples, the additional broad peak at -89.0 ppm, is due to the presence of amorphous K2Si2O5 phase. FE-SEM and WDS mapping of SrSiO3-delta and Sr0.80K0.20SiO3-delta shows the segregation of amorphous K2Si2O5 along the grain boundaries. High temperature impedance study of Sr0.80K0.20SiO3-delta exhibits the conductivity, which is comparable to other solid electrolytes in the literature, which makes it as promising solid electrolyte for intermediate temperature SOFCs. (C) 2018 Elsevier B.V. All rights reserved
Dielectrical performance of high-k yttrium copper titanate thin films for electronic applications
No full textThe increasing constraints in the miniaturization of modern electronic devices is driving the search for new high-k dielectric materials. Rare-earth transition metal oxides are very interesting because of the large values of dielectric constant observed in bulk samples. Here, we report on a comparison among the dielectric properties of yttrium copper titanate (YCTO) thin films and those of commonly used dielectrics such as SiO2 and MgO, grown in similar device structures. The YCTO permittivity was found to depend strongly on the oxygen pressure during deposition and can reach values even higher than those reported in bulk YCTO with good performances in terms of losses