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Low temperature below 200 degrees C solution processed tunable flash memory device without tunneling and blocking layer
No full textIntrinsic charge trap capacitive non-volatile flash memories take a significant share of the semiconductor electronics market today. It is challenging to create intrinsic traps in the dielectric layer without high temperature processing steps. The main issue is to optimize the leakage current and intrinsic trap density simultaneously. Moreover, conventional memory devices need the support of tunneling and blocking layers since the charge trapping dielectric layer is incapable of preventing the memory leakage. Here we report a tunable flash memory device without tunneling and blocking layer by combining the discovery of high intrinsic charge traps of more than 10(12 )cm(-2), together with low leakage current of less than 10(-7)A cm(-2) in solution derived, inorganic, spin-coated dielectric films which were heated at 200 degrees C or below. In addition, the memory storage capacity is tuned systematically upto 96% by controlling the trap density with increasing heating temperature
Search for a heavy resonance decaying to a top quark and a vector-like top quark in the lepton plus jets final state in pp collisions at root s=13 TeV
No full textA search is presented for a heavy spin- 1 resonance Z decaying to a top quark and a vector- like top quark partner T in the lepton + jets final state. The search is performed using a data set of pp collisions at a centre- of- mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb - 1 as recorded by the CMS experiment at the CERN LHC in the year 2016. The analysis is optimised for final states arising from the T decay modes to a top quark and a Higgs or Z boson ( T. Ht, Zt). The event selection makes use of resolved and merged top quark decay products, as well as decays of boosted Higgs bosons and Z and W bosons using jet substructure techniques. No significant deviation from the standard model background expectation is observed. Exclusion limits on the product of the cross section and branching fraction for Z . tT, T. Ht, Zt, Wb are presented for various combinations of the Z resonance mass and the vector- like T quark mass. These results represent the most stringent limits to date for the decay mode Z . tT. tHt. In a benchmark model with extra dimensions, invoking a heavy spin- 1 resonance G *, masses of the G * between 1.5 and 2.3 TeV and between 2.0 and 2.4 TeV are excluded for T masses of 1.2 and 1.5 TeV
Photophysical properties of novel fluorescent 1-(3-Hydroxy-benzofuran-2-yl)-benzof]chromen-3-one derivative: models for correlation solvent polarity scales
No full textPhotophysical and spectral properties of a new benzofuran-derivative-based fluorescent probe 1-(3-Hydroxybenzofuran-2-yl)-benzof]chromen-3-one (1-HBBC) were considered in various parameters of solvents, making use of UV-Vis absorption and fluorescence emission spectroscopy. The absorption and fluorescence emission peak maxima were observed between 260-349 and 400-485 nm, respectively, prompting Stokes' shift between 13 993 and 18 495 cm(-1). Diverse solvent parameters have been utilized to understand the solvatochromism of 1-HBBC. This information is applied to understand the effects of the solvent, on the shifting in the spectra of 1-HBBC and access the execution of empirical solvatochromic models: the well-known Kamlet-Taft model and two recent Catalan models. Linear solvation energy relationships proposed by the Kamlet-Taft treatment for the 1-HBBC molecule indicate that it is appealing as a molecule for the hydrogen bond and solvent polarity properties it has exhibited. The models offer good statistical execution for all solvents studied in this work. A general decency of fit is found for benzofuran values for the models' contractions, whereas these solvents are incorporated directly into the solvatochromic analysis. These reductions are comparable for the Kamlet-Taft and Catalan 4P models but important for the Catalan 3P model. The results shown herein can be used for outlining new luminescent tests for nonpolar and polar microenvironment
Tuning copper sulfide nanosheets by cation exchange reactions to realize two-dimensional CZTS dielectric layers
No full textDesign of two-dimensional (2D) quaternary copper-zinc-tin-sulfide (Cu2ZnSnS4, CZTS) nanosheets (NSs) consisting of purely earth abundant elements with desired morphologies, compositions and phases is challenging by conventional colloidal synthesis routes. Here we report the colloidal synthesis of ultra-thin (approximate to 2 nm) phase-pure 2D wurtzite CZTS NSs using 2D copper sulfide (Cu2S) NSs as a template. We incorporated Zn(ii) and Sn(iv) ions into the crystal lattice of Cu2S NSs retaining the 2D shape via controlled cation exchange reactions. The reaction protocol allows the achievement of the desired elemental composition of the NSs by varying the composition of the precursors. CZTS NSs with a large planar area exhibit a nearly temperature and frequency independent dielectric constant (>6.1) with a low dielectric loss over broad temperature and frequency ranges which makes the system an effective 2D dielectric material. The template based cation exchange reaction protocol provides a guideline to obtain phase-pure CZTS by avoiding the secondary phases often associated with the colloidal synthesis routes. This work demonstrates the realization of 2D quaternary dielectric non-oxide semiconductors composed of purely earth abundant elements for miniaturized energy storage devices using flexible solution processed routes
Assessing vulnerability of forest ecosystem in the Indian Western Himalayan region using trends of net primary productivity
No full textThe Himalayan ecosystem is one of the sensitive and fragile ecosystems with rich biodiversity that provides major ecosystem services. The study was conducted to measure the extent of vulnerability across forested grids of Uttarakhandone of the States of Indian Western Himalayan (IWH) region. The forests of the state are exposed to various anthropogenic and natural climatic pressures, thus making them vulnerable. In this paper, we demonstrate how to map vulnerability of forest ecosystem by analyzing variability and trends of net primary productivity (NPP). The vulnerability of the forest ecosystem was evaluated through trends of sensitivity and adaptability of NPP. The sensitivity of a system was considered as the response degree of the system to climatic variability whereas adaptability was considered as the ability to maintain, recover or improve its structure in the face of climatic stresses. In our study, NPP was considered as the receptor of shock and stresses of climatic variability and human disturbances. We discuss the method and results with reference to productivity changes under the influence of changing climate for the forested landscape of a mountainous region. The results have been summarized to rank vulnerability at the level of administrative boundary of governance, i.e. district. Average value of vulnerability for all NPP pixels of forests grids in a district was used to compute the vulnerability at district level. The study will help forest managers in decision making for efficiently allocating resources and to prioritize management options in the identified regions to improve productivity in coming times
In situ reversible redox switching of first hyperpolarizability of bimetallic ruthenium complexes
No full textIn this article we report the reversible redox switching of first hyperpolarizability of bimetallic ruthenium complexes bridged by bipyridyl tetrazine (bptz) ligands by second harmonic light scattering experiments (SHLS). We have synthesised RuII(acac) (2)(CH3CN) (2)] and (acac) Ru-2-bptz-Ru(acac) (2)] complexes and measured their first hyperpolarizabilities as a function of in situ electrochemical oxidation/reduction of the metal centres. As a result of the oxidation of ruthenium centre from Ru(II) to Ru(III), the molecular hyperpolarizability of the complexes went up. The mixed-valence intermediate bimetallic complex and not the fully oxidized complex exhibit the highest beta value of 780 X 10(-30) esu. We also demonstrated that the hyperpolarizability is reversible with the change of the oxidation state of the metal and both the complexes are stable for several cycles of redox switching. The experimental results are also supported by calculations
A Two-Terminal Bistable Electrothermally Actuated Microswitch
No full textAn improved design of an electrothermally actuated two-terminal bistable microswitch is the focus of this paper. The proposed design has bimodal bistability which is obtained by using a pair of arches, a V-beam electrothermal actuator, and a novel initially retracting actuator. All these elements are monolithically integrated in a single planar releasable layer. The salient feature of the design is the usage of only a single pair of electrodes to switch between ON and OFF states, even though there are two actuators. In order to reduce the stress, the two actuators are mechanically decoupled but are electrically coupled to satisfy the two-terminal actuation. The switch design is experimentally verified by realizing on a silicon-on-insulator (SOI) wafer using a single-layer micro-fabrication technique. An actuation voltage of 11.8 V with 200-ms pulse-width, drives the switch from OFF to ON state and a 50-ms pulse of the same voltage across the same terminals, brings it back
Effect of thermo-mechanical treatment on microstructure and tensile properties of 2219ScMg alloy
No full textAn improved high temperature performance of 2219 aluminium alloys through thermo-mechanical treatments having additions of 0.8 wt% Sc and 0.45 wt% Mg is presented. The copper mould chill cast alloy designated as 2219ScMg is processed through two different routes. In the first route, designated here as HMCR process, the alloy is homogenised at 530 degrees C and cold rolled, while in the second route, designated here as HRCR process, the cast alloy is directly rolled sequentially under hot and cold conditions. The evolution of the microstructure and strength are examined throughout the processes. The formation of L1(2) ordered Al3Sc and Al-3(Sc, Zr) precipitates of average size 10 +/- 5.5 nm (radius) takes place during solidification. In the HMCR process, homogenization of the alloy at 530 degrees C results in an increase in the number density of these precipitates in addition to partial dissolution of copper in the Al matrix. Subsequent cold rolling of the alloy introduces strain hardening. The same thing happens during hot rolling at 300 degrees C in HRCR process but the size of the Al3Sc/Al-3(Sc, Zr) precipitates is smaller. The subsequent cold rolling again strain hardens the alloy. In addition to excellent room temperature 0.2% proof stress of similar to 500 MPa in both the processes, outstanding elevated temperature (200 degrees C) 0.2% proof stress of 345 MPa in HMCR and 312 MPa in HRCR is obtained. Thermal stability of the alloy at elevated temperature is enhanced by the Sc and Mg segregation at the Al/theta' interface and the formation of a small amount of Omega phase
A Plastic Boundary Layer in Wedge Indentation of Aluminum
No full textWe study plastic flow in the vicinity of an indenter-material interface in wedge indentation of aluminum using high speed in situ imaging and particle image velocimetry (PIV) analysis. Displacement and strain fields in the indentation zone are obtained at high-resolution for different indenter angles and two lubrication conditions. These fields can be used to demarcate essential features of the material flow phenomena. The deformed layers close to the indenter wall fit a classical boundary layer profile in the framework of a Bingham-solid. Equivalent Bingham viscosities and boundary layer scaling relations are obtained. The viscosity values appear to reflect the nature of the friction interaction at the indenter-material interface and can potentially be used as a discriminating parameter for evaluating contributions to deformation and dissipation arising from interface friction
Estimating Strengths of Individual Hydrogen Bonds in RNA Base Pairs: Toward a Consensus between Different Computational Approaches
No full textNoncoding RNA molecules are composed of a large variety of noncanonical base pairs that shape up their functionally competent folded structures. Each base pair is composed of at least two interbase hydrogen bonds (H-bonds). It is expected that the characteristic geometry and stability of different noncanonical base pairs are determined collectively by the properties of these interbase H-bonds. We have studied the ground-state electronic properties using density functional theory (DFT) and DFT-D3-based methods] of all the 118 normal base pairs and 36 modified base pairs, belonging to 12 different geometric families (cis and trans of WW, WH, HH, WS, HS, and SS) that occur in a nonredundant set of high-resolution RNA crystal structures. Having addressed some of the limitations of the earlier approaches, we provide here a comprehensive compilation of the average energies of different types of interbase H-bonds (E-HB). We have also characterized each interbase H-bond using 13 different parameters that describe its geometry, charge distribution at its bond critical point (BCP), and n -> sigma*-type charge transfer from filled pi orbitals of the H-bond acceptor to the empty antibonding orbital of the H-bond donor. On the basis of the extent of their linear correlation with the H-bonding energy, we have shortlisted five parameters to model linear equations for predicting E-HB values. They are (i) electron density at the BCP: rho, (ii) its Laplacian: del(2)rho, (iii) stabilization energy due to n -> sigma*-type charge transfer: E(2), (iv) donor-hydrogen distance, and (v) hydrogen-acceptor distance. We have performed single variable and multivariable linear regression analysis over the normal base pairs and have modeled sets of linear relationships between these five parameters and E-HB. Performance testing of our model over the set of modified base pairs shows promising results, at least for the moderately strong H-bonds