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Synthesis and characterization of N,N ',C-bound organotellurium(IV) and organomercury(II) derivatives
No full textWe report the synthesis and characterization of the first examples of organotellurium (IV)/organomercury(II) derivatives of N,N',C-chelating aryldiamine ligand, 2-{Me2NCH2CH2N(Me)CH2}C6H4Br (20). The dichalcogenides, [2-{Me2NCH2CH2N(Me)CH2}C6H4Se](2) (24) and [2-{Me2NCH2CH2N(Me)CH2}C6H4Te](2) (25), were prepared by treatment of the corresponding Grignard reagent (21)/organolithium reagent (22) in THF with selenium or tellurium, respectively. Compounds [2-{Me2NCH2CH2N(Me)CH2}C6H4](2)Se (26) and [2-{Me2NCH2CH2N(Me)CH2}C6H4]Te(S2CN(CH2CH3)(2) (27) were synthesized by the reaction of 21/22 with Se(dtc)(2) in 2:1 or Te(dtc)(2) (dtc = diethyldithiacarbamate) in 1:1 ratio at room temperature. In contrast, the reaction of 21 with TeI2 afforded an unexpected protonated derivative, [2-{(Me2NCH2CH2N(Me)CH2}C6H4TeI](+)(I)(-) (28a). Similarly, the halogenation reactions of 25 with chlorine gas or a solution of bromine in THF afforded protonated derivatives, [2-{(Me2NCH2CH2N(Me)CH2}C6H4TeCl3](+) (Cl)(-) (29a) and [2-{(Me2NCH2CH2N(Me)CH2}C6H4TeBr3](+) (Br) (-) (30a), respectively. The organomercury precursors; 2-{Me2NCH2CH2N(Me)CH2}C6H4HgCl0.54/Br-0.46 (31) and 2-{Me2NCH2CH2N(Me)CH2}C6H4HgBr (32), were obtained by the reaction of 21 with HgCl2 and HgBr2 in dry THF, respectively. The metathetical reaction of 3lwith silver azide afforded air- and moisture-stable organomercury azide, 2-{Me2NCH2CH2N(Me)CH2}C6H4HgN3 (33) in 87% yield. The transmetallation reaction of 31 with TeBr4 led to isolation of known o-formylphenyltellurenyl bromide. All the derivatives were characterized by various spectroscopic techniques such as H-1, C-13, Se-77, Te-125, Hg-199 NMR spectroscopy, elemental analysis, ES-MS and HAMS studies
Effects of Basalt and Hydrated Lime Fillers on Rheological and Fracture Cracking Behavior of Polymer Modified Asphalt Mastic
No full textThis paper investigates the influence of basalt (B) and hydrated lime (HL) fillers on the rheological and fracture performance behavior of asphalt mastics. A polymer modified asphalt (PMA) binder (PMB-40), basalt (inert filler), and hydrated lime (active filler, are considered for preparation of PMA mastic. Five different combinations of B and HL fillers are selected for the preparation of different PMA mastics with filler:binder ratio of 0.8:1 (22.5% by volume). The rheological response of PMA mastic is investigated based on Superpave rutting factor, fatigue factor, and linear amplitude sweep (LAS) test results using a dynamic shear rheometer (DSR). Fracture characterization of PMA mastics is evaluated using a double-edge notched tension (DENT) test. Hydrated lime significantly improves rut resistance of PMA mastics at high temperatures. Superpave fatigue factor and LAS test results show that PMA mastic containing high dosages of HL (10-20%) has low resistance to fatigue cracking and is more susceptible to strain amplitude at intermediate temperatures. Mastic without HL predominantly shows better fracture resistance behavior with good critical tip opening displacement (CTOD) value than does PMA mastic containing high dosages of HL (10-20%). High dosages of HL (10-20%) increase high-temperature aging susceptibility by influencing the rheological performance. The PMA mastics are ranked based on various performance parameters. This study shows that the combination of B with high dosages of HL filler may not enhance the fatigue and fracture resistance of PMA mastic. (C) 2018 American Society of Civil Engineers
Snow Cover Mapping Using Polarization Fraction Variation With Temporal RADARSAT-2 C-Band Full-Polarimetric SAR Data Over the Indian Himalayas
No full textRemote sensing is an indispensable tool for Earth observation over large areal extent. Snow cover extent monitoring has been one such application where microwave sensors have been a popular choice due to their sensitivity toward the dielectric property. Snow is a dynamic matter since its dielectric state is dependent on climatic factors prevailing locally around it. In the literature, the polarization fraction (PF) has been used for landcover characterization. In this paper, we utilize the seasonal variation of the PF for mapping snow cover over the Himalayan terrain. Temporal variation of the strength in the polarized return due to change in landcover and season is the prime motivation behind this approach. In addition, the effect of SAR data acquisition time on mapping algorithms is considered in this work which is seldom discussed in the literature. Furthermore, a study is conducted to analyze the seasonal variation in the entropy (H) and the scattering type (a) parameters over the bare snow-covered ground and the forested areas. The seasonal response of the terrain in the H/a plane corresponding to specific scattering characteristics is analyzed. The applicability of the approach is tested with RADARSAT-2 (FQ28) C-band full polarimetric image pairs over the Manali-Dhundi region, Himachal Pradesh, India, located in the western Hindu-Kush Himalayas. The snow cover map is explicitly validated with in situ observatory measurements and optical satellite imagery
Magnetocaloric effect and critical behavior study in NiMnSnIn Heusler alloys
No full textIn the present work, polycrystalline Ni50Mn36Sn14-xInx (x = 0, 1, 2 and 3) Heusler alloys were prepared. The influence of In substitution for Sn on the crystal structure, martensitic transition (MT) and magnetic properties have been investigated for these alloys. Structural analysis indicate that the samples possess L2(1) structure at room temperature. With increasing In content, the martensitic transition shifts to a higher temperature, while the Curie temperature of austenite phase moves to a lower temperature. The maximum entropy change (Delta S-M)(max) near the martensitic transition is found to be 8.4 J/kgK, 9.8 J/kgK, 10.1 J/kgK and 19.2 J/kgK for x = 0, 1, 2 and 3 respectively, for a field change of 50 kOe. The entropy change around the Curie temperature of the austenite phase is found to be - 2.9 J/kgK, -1.8 J/kgK, - 4.1 J/kgK and - 3.9 J/kgK respectively for x = 0, 1, 2 and 3 alloys, for a field change of 50 kOe. The effective RCP values are 80 J/kg, 15.6 J/kg, 65.8 J/kg and 69.4 J/kg for x = 0, 1, 2 and 3 alloys respectively, near the first order transition region. The RCP values are higher around the second order transition region due to the broad nature of dS m curves. The corresponding values are 114 J/kg, 92 J/kg, 121 J/kg and 132 J/kg for x = 0, 1, 2 and 3 alloys, respectively. Moreover, the critical behavior of Ni50Mn36Sn14-xInx (x = 1, 2 and 3) Heusler alloys around the ferromagnetic-paramagnetic transition region of austenite phase is studied from the field dependence of magnetic entropy change. The critical exponent values are close to the theoretical prediction of mean field model with a slight deviation
Deciphering the Dynamical Origin of Mixed Population during Neural Stem Cell Development
No full textNeural stem cells (NSCs) often give rise to a mixed population of cells during differentiation. However, the dynamical origin of these mixed states is poorly understood. In this article, our mathematical modeling study demonstrates that the bone morphogenetic protein 2 (BMP2) mediated disparate differentiation dynamics of NSCs in central and peripheral nervous systems essentially function through two distinct bistable switches that are mutually interconnected via a mushroom-like bifurcation. Stochastic simulations of the model reveal that the mixed population originates due to the existence of these bistable switching regulations and that the maintenance of such mixed states depends on the level of stochastic fluctuations of the system. It further demonstrates that due to extrinsic variability, cells in an NSC population can dynamically transit from mushroom to a unique isola kind of bifurcation state, which essentially extends the range of the BMP2-driven mixed population state during differentiation. Importantly, the model predicts that by individually altering the expression level of key regulatory proteins, the NSCs can be converted entirely to a preferred phenotype for BMP2 doses that previously resulted in a mixed population. Our findings show that efficient neuronal regeneration can be achieved by systematically maneuvering the differentiation dynamics
Supported ammonia borane decomposition through enhanced homopolar B B coupling
No full textThe thermolytic decomposition of ammonia borane (AB) is known to proceed through the polymeric coupling reaction between -BH3 and -NH3 sites of multiple ammonia borane molecules, which results in the release of hydrogen and other by-products, e.g., ammonia, diborane and borazine. The formation of these by-products concomitantly pollutes the hydrogen stream, and therefore, it is necessary to remove these gases from the product stream. In the current work, a cost effective and easy to synthesize support material, aluminium phosphate (AP), is introduced in AB thermolytic decomposition. An in situ MS study reveals that the AB and AP (w/w) loading ratio of (1 x 4) is the most promising as it is able to minimise the dehydrogenation peak temperature by 18.89 degrees C compared to that of pure AB. Additionally, in the presence of support material, the by-product formation of ammonia is reduced by 70.3%, with a complete suppression in borazine and diborane release. The mechanism behind the by-product suppression of supported AB has been studied through B-11 MAS NMR analysis which suggests that the release of hydrogen occurs through an intermolecular homopolar B-B bonding. The thermogravimetric and kinetic study also reveals that in the case of supported AB decomposition, hydrogen release through B-B interaction is much more efficient than a B-N interaction, thus limiting the possibility of autocatalysis during the supported decomposition reaction
Analytical modeling of metal gate granularity based threshold voltage variability in NWFET
No full textEstimation of threshold voltage V-T variability for NWFETs has been computationally expensive due to lack of analytical models. Variability estimation of NWFET is essential to design the next generation logic circuits. Compared to any other process induced variabilities, Metal Gate Granularity (MGG) is of paramount importance due to its large impact on V-T variability. Here, an analytical model is proposed to estimate V-T variability caused by MGG. We extend our earlier FinFET based MGG model to a cylindrical NWFET by satisfying three additional requirements. First, the gate dielectric layer is replaced by Silicon of electro-statically equivalent thickness using long cylinder approximation; Second, metal grains in NWFETs satisfy periodic boundary condition in azimuthal direction; Third, electrostatics is analytically solved in cylindrical polar coordinates with gate boundary condition defined by MGG. We show that quantum effects only shift the mean of the V-T distribution without significant impact on the variability estimated by our electrostatics-based model. The V-T distribution estimated by our model matches TCAD simulations. The model quantitatively captures grain size dependence with o - (V-T) with excellent accuracy (6%error) compared to stochastic 3D TCAD simulations, which is a significant improvement over the state-of- the-art model with fails to produce even a qualitative agreement. The proposed model is 63x faster compared to commercial TCAD simulations
Influence of petal parameters on the electromagnetic force driving the arc in RMF type vacuum interrupters
No full textThe SWASTIK type radial magnetic field (RMF) contact design is widely used in vacuum interrupters. The mutually perpendicular petal limbs are a unique feature of this contact design. The focus of this work is to relate the Lorentz force acting on the arc with petal dimensions through closed-form expressions. Considering the petal limbs as equivalent to finite current carrying conductors, analytical equations are derived to compute the magnetic flux density at any point in space. The results are verified by using finite-element method (FEM) simulations of rail electrodes. The expressions are then used to compute the Lorentz force on the arc in SWASTIK contacts. The analytical predictions are compared with three-dimensional FEM simulations of a CAD model of the contacts. Applicability of the analytical results is investigated in the context of parametric variation of the radius, length and position of the arc and temporal variation of the contact current. The present work can be used in the first iteration of contact petal design. It is also applicable for the design of rail gun geometries
Structure, mechanical properties and evolution of the lithosphere below the northwest continental margin of India
No full textThe continental breakup history at the northwest continental margin of India remained conjectural due to lack of clearly discernable magnetic anomaly identifications and the presence of several enigmatic structural/basement features whose structure was partly obscured by the Late Cretaceous Deccan magmatic event. In this study, a detailed analysis of the existing seismic and seismological data covering both onshore and offshore areas of the northwest Indian margin along with 3-D/2-D constrained potential field (gravity, magnetic and geoid) modeling has been carried out. The crustal structure and lithosphere-asthenosphere boundary (LAB) delineated across the margin provided valuable insights on the mechanism of continental extension. An analysis of the residual geoid anomaly (degree-10) map and the modeled LAB below Deccan volcanic province (DVP) revealed significant variation in upper mantle characteristics between the northwest (NW) and south central (SC) parts of DVP having thinner lithosphere in the NW part. The depth to LAB ranges 80-130 km at the margin with gradual thinning towards the western offshore having sharp gradient in the south (SC part of DVP) and gentle gradient in the north (NW part of DVP). The Moho configuration obtained from seismically constrained 3-D gravity inversion reveals that Moho depths vary 34-42 km below DVP and gradually thins to 16-20 km in the western offshore. The effective elastic thickness (Te) map computed through 3-D flexural modeling indicates that the Te values are in general lower in the region and range 12-25 km. Such lower Te values could be ascribed to the combined effect of the lithosphere stretching during Gondwana fragmentation in the Mesozoic and subsequent thermal influence of the Reunion plume. Based on the crustal stretching factors (beta), Te estimates and the modeled lithosphere geometry at the margin in this study, we propose that the lithosphere below Laxmi-Gop basin region (beta > 3.0) had undergone continuous stretching since India-Madagascar rifting (similar to 88 Ma) /much prior to this event. However, this continuous stretching did not lead to breakup. Due to syn-rift cooling, the developed necking zone (brittle-ductile deformation) got ceased and led to the development of a new necking zone between Seychelles and Laxmi Ridge. Subsequent stretching between Seychelles and the Laxmi Ridge contemporaneous with the Deccan flood basalts eruption led to the seafloor spreading in the Western Basin (anomaly C28n). Thus, the Laxmi Ridge became a continental sliver
Reaction of PdCl2 with Diphenylacetylene Revisited: Effect of Solvents and Ball Milling on Cyclization and Crystal Structures of Dimeric Cyclobutenylpalladium Chloride Complexes
No full textIn an attempt to establish the structures of the product formed in the reaction of PdCl2 and diphenylacetylene in polar organic solvents, the reactions were carried out in alcohols, acetonitrile and tetrahydrofuran at room temperature. The reactions in protic solvents such as primary and secondary alcohols resulted in the cyclic dimerization of diphenylacetylene to yield the corresponding dimeric endo-4-alkoxy-pi-1,2,3,4-tetraphenylcyclobutenypalladium(II) chloride complexes 1-4 in good yields. In these complexes the tetraphenylcyclobutenyl moieties are coordinated to palladium atoms in eta(3)-mode and are bridged by two chlorides as confirmed by the single crystal X-ray analysis of complexes 1, 2 and 4. In all these complexes, the coordination of cyclobutenyl moieties to palladium atoms are similar but a marked difference was observed for the Pd2Cl2 core which is planar in complex 1 but puckered in complexes 2 and 4 resulting in shorter PdPd distances. The same reaction under solvent free ball milling condition yielded hexaphenylbenzene by the cyclic trimerization while that in the presence of ethanol and n-butanol produced complexes 1 and 3, respectively, as major and hexaphenylbenzene as minor product. An efficient catalytic synthesis of hexaphenylbenzene using PdCl2 was developed using ball milling condition which has several advantages over the existing catalytic systems