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Performance evaluation of satellite-based approaches for the estimation of daily air temperature and reference evapotranspiration
No full textDifferent satellite-based radiation (Makkink) and temperature (Hargreaves-Samani, Penman-Monteith temperature, PMT) reference evapotranspiration (ETo) models were compared with the FAO56-PM method over the Cauvery basin, India. Maximum air temperature (T-max) required in the ETo models was estimated using the temperature-vegetation index (TVX) and an advanced statistical approach (ASA), and evaluated with observed T-max obtained from automatic weather stations. Minimum air temperature (T-min) was estimated using ASA. Land surface temperature was employed in the ETo models in place of air temperature (T-a) to check the potency of its applicability. The results suggest that the PMT model with T-a as input performed better than the other ETo models, with correlation coefficient (r), averaged root mean square error (RMSE) and mean bias error (MBE) of 0.77, 0.80 mm d(-1) and -0.69 for all land cover classes. The ASA yielded better T-max and T-min values (r and RMSE of 0.87 and 2.17 degrees C, and 0.87 and 2.27 degrees C, respectively)
AN EXPERIMENTAL STUDY OF WEDGE INDENTATION OF POROUS SOLIDS: IMPLICATIONS FOR CUTTING AND DRILLING PROCESSES
No full textAn experimental study of mechanics of wedge indentation of porous solids is carried out under plane-strain conditions. A comparison is made between the porous ductile copper and porous brittle gypsum to study the influence of matrix material on the indentation behavior. Image-based measurement techniques are used to capture the evolution of deformation zone and obtain quantitative velocity, strain and volume change fields at high resolution. The results show that despite widely different characteristics of the matrix material, the overall deformation zone evolves in a manner that is largely similar across material systems. Porous copper exhibits a smoothly varying radial compression-type plastic flow within the deformation zone, while localized flow features (compaction bands) are typical of gypsum. Implications of our observations on wedge indentation for modeling complex machining geometries such as cutting and drilling are briefly discussed
Aggregation-Induced Emission and White Luminescence from a Combination of pi-Conjugated Donor-Acceptor Organic Luminogens
No full textTwo new star-shaped phenyl- and triazine-core based donor-acceptor (D-A) type conjugated molecules bearing triphenylamine end-capped arms were synthesized and characterized as imminent organic optoelectronic materials. Photophysical properties of the compounds were explored systematically via spectroscopic and theoretical methods. Because of the presence of donor-acceptor interactions, these luminogens display multifunctional properties, for instance, high extinction coefficient, large stokes shift, and pronounced solvatochromic effect. The compounds also exhibited phenomenon known as aggregation-induced emission on formation of nano-aggregates in the tetrahydrofuran-water mixture. The aggregate formation was confirmed by transmission electron microscopy, scanning electron microscopy, and dynamic light scattering analyses. Moreover, by controlling the electron withdrawing ability of the acceptor, complementary emissive fluorophores (blue and yellow) were achieved. These two complementary colors together span the entire range of visible spectrum (400-800 nm) and therefore when mixed in a requisite proportion generate white light in solution phase. These findings have potential for the progress of new organic white light radiating materials for applications in lighting and display devices
L-Dopa and dopamine conjugated naphthalenediimides modulate amyloid beta toxicity
No full textThe process of protein misfolding and aggregation to form neurotoxic species is strongly implicated in most of the neurodegenerative disorders. In particular, amyloid beta (A) misfolding and aggregation is central to pathophysiological processes of Alzheimer's disease. The development of aggregation modulators has enormous implications in the discovery of effective therapeutic agents for Alzheimer's disease. Herein, we report the design and synthesis of a series of natural amino acid, l-dopa and dopamine appended derivatives of naphthalenediimide (NDI) to identify efficient aggregation modulators. Furthermore, the molecular docking studies revealed the possible binding sites and binding mode of NDI-conjugates to A aggregates. Among the designed NDI-conjugates, l-dopa and dopamine derivatives (NLD and NDP, respectively) showed excellent aggregation modulation efficiency (inhibition and dissolution), as shown by the thioflavin T (ThT) binding assays, dot blot analysis and in cellulo studies. The docking results from in silico studies are in good agreement with the experimental data. In addition to their significant modulation efficiency towards A aggregation, NLD and NDP possess antioxidant activity conducive to the development of disease-modifying therapeutic agents for the treatment of Alzheimer's disease
Strange half-metals and Mott insulators in Sachdev-Ye-Kitaev models
No full textWe study a two-flavor fermion model where each of the flavors form a Sachdev-Ye-Kitaev (SYK) system with arbitrary q -body interactions. The crucial new element is an all-to-all r -body interaction between the two flavors. At high temperatures, the model shows a strange metal phase where both flavors are gapless, similar to the usual single-flavor SYK model. Upon reducing temperature, the coupled system undergoes transitions to previously unseen phases in the SYK framework-first, a strange half-metal phase where one flavor remains a strange metal while the other is gapped, and second, an insulating phase of the Mott kind where both flavors are gapped. At a fixed low temperature, we obtain transitions between these phases by tuning the relative fraction of sites for each flavor. We discuss the physics of these phases and the nature of transitions between them. This work provides an example of an instability of the strange metal with potential to provide new routes to study strongly correlated systems through the rich physics contained in SYK-like models
Benzimidazolium-based high temperature ionic liquid-in-oil microemulsion for regioselective nitration reaction
No full textOwing to the fascinating applications of ionic liquids (ILs) based non-aqueous microemulsions (MEs) in the field of chemical reactions due to their high thermal stability compared to that of aqueous MEs and requirement of water-free environment, we designed a high-temperature stable cationic IL-in-oil microemulsions using 1-ethyl-3-propylbenzimidazolium bromide (EPbim]Br) as a polar phase for the first time. In order to determine the thermodynamic stability of such type of MEs, we measured the distribution of cosurfactant (herein, 1-octanol) between bulk n-decane phase and interface covered by quaternary ammonium head group of cetyltrimethylammonium bromide (CTAB) at elevated temperature. The spontaneous formulation of high-temperature IL-in-oil MEs with organized IL-oil interface was identified by the negative free energy and entropy change at studied temperature range (358-370 K). Interestingly, we observed temperature-independent exothermic behavior at a specific composition, which probably comes from the cation-pi interaction between quaternary ammonium head group of CTAB and aromatic moiety of ILs. We performed phase behavior study to demonstrate a wide range of thermally stable of EPbim](Br]/CTAB/decane MEs. Surprisingly, the droplet size was decreased with progressive addition of IL, which may be due to the difficulty of formation of strong and favourable H-bond between the polar head groups of CTAB and EPbim]Br] at higher temperature. Furthermore, the aggregation number and molecular interfacial area at higher temperature were calculated, which have direct correlation with the droplet size. Finally, the nitration reaction with three different aromatic compounds was performed in this MEs media at the temperature-independent composition. The reaction was completed with the highest regioseletivity-of para isomer product over the ortho one. Moreover, these results clearly highlight an efficient way towards the formulation of high temperature stable MEs with ILs at ambient pressure and open a wide field of potential applications. (C) 2018 Elsevier B.V. All rights reserved
Domain architecture of BAF250a reveals the ARID and ARM-repeat domains with implication in function and assembly of the BAF remodeling complex
No full textBAF250a and BAF250b are subunits of the SWI/SNF chromatin-remodeling complex that recruit the complex to chromatin allowing transcriptional activation of several genes. Despite being the central subunits of the SWI/SNF complex, the structural and functional annotation of BAF250a/b remains poorly understood. BAF250a (nearly 2200 residues protein) harbors an N-terminal DNA binding ARID (similar to 110 residues) and a C-terminal folded region (similar to 250 residues) of unknown structure and function, recently annotated as BAF250_C. Using hydrophobic core analysis, fold prediction and comparative modeling, here we have defined a domain boundary and associate a beta-catenin like ARM-repeat fold to the C-terminus of BAF250a that encompass BAF250_C. The N-terminal DNA-binding ARID is found in diverse domain combinations in proteins imparting unique functions. We used a comparative sequence analysis based approach to study the ARIDs from diverse domain contexts and identified conserved residue positions that are important to preserve its core structure. Supporting this, mutation of one such conserved residue valine, at position 1067, to glycine, resulted in destabilization, loss of structural integrity and DNA binding affinity of ARID. Additionally, we identified a set of conserved and surface-exposed residues unique to the ARID when it co-occurs with the ARM repeat containing BAF250_C in BAF250a. Several of these residues are found mutated in somatic cancers. We predict that these residues in BAF250a may play important roles in mediating protein-DNA and protein-protein interactions in the BAF complex
Distinct mechanisms explain the control of reach speed planning: evidence from a race model framework
No full textPrevious studies have investigated the computational architecture underlying the voluntary control of reach movements that demands a change in position or direction of movement planning. Here we used a novel task in which subjects had to either increase or decrease the movement speed according to a change in target color that occurred randomly during a trial. The applicability of different race models to such a speed redirect task was assessed. We found that the predictions of an independent race model that instantiated an abort-and-replan strategy was consistent with all aspects of performance in the fast-to-slow speed condition. The results from modeling indicated a peculiar asymmetry, in that although the fast-to-slow speed change required inhibition, none of the standard race models was able to explain how movements changed from slow to fast speeds. Interestingly, a weighted averaging model that simulated the gradual merging of two kinematic plans explained behavior in the slow-to-fast speed task. In summary, our work shows how a race model framework can provide an understanding of how the brain controls different aspects of reach movement planning and help distinguish between an abort-and-replan strategy and merging of plans. NEW & NOTEWORTHY For the first time, a race model framework was used to understand how reach speeds are modified. We provide evidence that a fast-to-slow speed change required aborting the current plan and a complete respecification of a new plan, while none of the race models was able to explain an instructed increase of hand movement speed, which was instead accomplished by a merging of a new kinematic plan with the existing kinematic plan
Low power consumption pressure sensor based on carbon nanotubes
No full textHere, we have shown that the current through the films made from nitrogen-doped carbon nanotubes (NCNTs) changes as the pressure is varied between 93 and 1000 mbar. The change is due to adsorption and desorption of ambient oxygen. Interestingly, the devices show good responsivity even when the power is in microwatts range. Over all, a low cost and low power pressure sensor made from NCNTs were fabricated and their usefulness was demonstrated. We believe the same can also be used as an oxygen sensor
Probabilistic strength based matrix crack evolution model in multidirectional composite laminates under fatigue loading
No full textA model to predict the matrix crack evolution in multi-directional (MD) polymer matrix composite laminates under in-plane fatigue loading is presented in the current work. Unlike matrix crack evolution under static loading, the matrix cracks in off-axis plies do not form tunneling cracks under fatigue loading; rather, they initiate and grow with increasing load cycles. A probabilistic strength based criterion for matrix crack initiation in off-axis plies based on a Weibull distribution for in situ ply strength variation has been used. An oblique coordinate based shear lag analysis has been used to estimate the stresses in the cracked laminate. Smith Watson Topper (SWT) parameter has been used to model the number of cycles to initiate the first matrix crack, and log-normal probability distribution has been used to handle the scatter in crack initiation life. The matrix crack growth rate has been modeled using Paris law based on mixed mode effective stress intensity factor. Using the crack initiation curve and strength degradation based on Palmgren-Miner damage rule, new crack initiation has been simulated. Few parameters needed for the threshold stress intensity and saturation crack spacing have been identified from a reference stress data of cross-ply laminate. The crack density evolution has been simulated for cross-ply and MD-laminates under various constant amplitude in-plane fatigue stress levels. The matrix crack density evolution and its stiffness degradation predictions with the number of cycles have been compared with existing experimental values. A good correlation is found to exist between the experimental data and predictions for both cross-ply and MD-laminates