Effect of distribution shape on the melting transition, local ordering,and dynamics in a model size-polydisperse two-dimensional fluid

We study the effect of particle size polydispersity(δ) on the melting transition(T*), local ordering, solid–liquid coexistence phase and dynamics of two-dimensional Lennard–Jones fluids up to moderate polydispersity by means of computer simulations. The particle sizes are drawn at random from the Gaussian(G) and uniform(U) distribution functions.For these systems, we further consider two different kinds of particles, viz., particles having the same mass irrespective of size, and in the other case the mass of the particle scales with its size. It is observed that with increasing polydispersity,the value of T*initially increases due to improved packing efficiency(φ) followed by a decrease and terminates at δ ≈8%(U-system) and 14%(G-system) with no significant difference for both mass types. The interesting observation is that the particular value at which φ drops suddenly coincides with the peak of the heat capacity(CP) curve, indicating a transition. The quantification of local particle ordering through the hexatic order parameter(Q_6), Voronoi construction and pair correlation function reveals that the ordering decreases with increasing δ and T. Furthermore, the solid–liquid coexistence region for the G-system is shown to be comparatively wider in the T –δ plane phase diagram than that for the U system. Finally, the study of dynamics reveals that polydisperse systems relax faster compared to monodisperse systems;however, no significant qualitative differences, depending on the distribution type and mass polydispersity, are observed.

Charge transport properties and variable photo-switching of three-terminal Cs_(2)AgBiBr_(6)device

In this study,we present an in-depth exploration of charge transport phenomena and variable photo-switching characteristics in a novel double-perovskite-based three-terminal device.The Cs_(2)AgBiBr_(6)thin film(TF)was synthesized through a three-step thermal evaporation process followed by precise open-air annealing,ensuring superior film quality as confirmed by structural and morphological characterizations.Photoluminescence spectroscopy revealed distinct emissions at 2.28 and 2.07 eV,indicative of both direct and indirect electronic transitions.Our device exhibited space-charge limited current(SCLC)behaviour beyond 0.35 V,aligning with the relationship Current(I)∝Voltage(V)^(m),where the exponent m transitioned from≤1 to>1.Detailed analysis of Schottky parameters within the trap-filled limit(TFL)regime was conducted,accounting for variations in temperature and optical power.Significantly,the self-powered photodetector demonstrated outstanding performance under illumination.The sensitivity of the device was finely tunable via the applied bias voltages at the third terminal.Notably,an optimal bias voltage of±100μV yielded maximum responsivity(R)of 0.48 A/W and an impressive detectivity(D*)of 1.07×10^(9)Jones,highlighting the potential of this double-perovskite-based device for advanced optoelectronic applications.

Electronic properties of 2D materials and their junctions

With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2D materials,knowledge of 2D electrical transport and carrier dynamics still in its infancy.Thus,here we highlighted the electrical characteristics of 2D materials with electronic band structure,electronic transport,dielectric constant,carriers mobility.The atomic thinness of 2D materials makes substantially scaled field-effect transistors(FETs)with reduced short-channel effects conceivable,even though strong carrier mobility required for high performance,low-voltage device operations.We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications.Presently,Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure.2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors.We also,describe the numerous 2D p-n junctions,such as homo junction and hetero junction including mixed dimensional junctions.Finally,we talked about the problems and potential for the future.

Qualitative Abnormalities of Peripheral Blood Smear Images Using Deep Learning Techniques

In recent years,Peripheral blood smear is a generic analysis to assess the person’s health status.Manual testing of Peripheral blood smear images are difficult,time-consuming and is subject to human intervention and visual error.This method encouraged for researchers to present algorithms and techniques to perform the peripheral blood smear analysis with the help of computer-assisted and decision-making techniques.Existing CAD based methods are lacks in attaining the accurate detection of abnormalities present in the images.In order to mitigate this issue Deep Convolution Neural Network(DCNN)based automatic classification technique is introduced with the classification of eight groups of peripheral blood cells such as basophil,eosinophil,lymphocyte,monocyte,neutrophil,erythroblast,platelet,myocyte,promyocyte and metamyocyte.The proposed DCNN model employs transfer learning approach and additionally it carries three stages such as pre-processing,feature extraction and classification.Initially the pre-processing steps are incorporated to eliminate noisy contents present in the image by using Histogram Equalization(HE).It is enclosed to improve an image contrast.In order to distinguish the dissimilar class and segmentation approach is carried out with the help of Fuzzy C-Means(FCM)model whereas its centroid point optimality method with Slap Swarm based optimization strategy.Moreover some specific set of Gray Level Co-occurrence Matrix(GLCM)features of the segmented images are extracted to augment the performance of proposed detection algorithm.Finally the extracted features are recorded by DCNN and the proposed classifier has the capability to extract their own features.Based on this the diverse set of classes are classified and distinguished from qualitative abnormalities found in the image.

Thermal conductivity of carbon nanotube-silver composite

The molecular level mixing method was extended to fabricate carbon nanotube reinforced silver composite. The influence of type of carbon nanotubes（single/multiwall） reinforcement and their mode of functionalization（covalent/non-covalent） on thermal conductivity of silver composite was investigated. X-ray diffraction and electron diffraction spectroscopy（EDS） confirm the presence of silver and carbon in the composite powder. High resolution scanning electron microscopy and transmission electron microscopy ascertain embedded, anchored and homogeneously implanted carbon nanotubes in silver matrix. Effect of covalent functionalization on multiwall carbon nanotubes was monitored by Raman and Fourier transform infrared spectroscopy. These investigations confirm the addition of functional groups and structural integrity of carbon nanotubes even after covalent functionalization. Thermal conductivity of composites was measured by a laser flash technique and theoretically analyzed using an effective medium approach. The experimental results reveal that thermal conductivity decreases after incorporation of covalently functionalized multiwall nanotubes and single wall carbon nanotubes. However, non-covalently functionalized multiwall nanotube reinforcement leads to the increase in effective thermal conductivity of the composite and is in agreement with theoretical predictions derived from effective medium theory, in absence of interfacial thermal resistance.

Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver–palladium alloy composites

The mechanical, electrical, and thermal expansion properties of carbon nanotube（CNT）-based silver and silver–palladium（10：1, w/w） alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young＇s modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion（CTE）. The hardness and Young＇s modulus of the nanocomposites were increased by 30%？40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.

Chemical, mechanical, and thermal expansion properties of a carbon nanotube-reinforced aluminum nanocomposite

In the present study,the chemical and mechanical properties and the thermal expansion of a carbon nanotube（CNT）-based crystalline nano-aluminum（nano Al） composite were reported.The properties of nanocomposites were tailored by incorporating CNTs into the nano Al matrix using a physical mixing method.The elastic moduli and the coefficient of thermal expansion（CTE） of the nanocomposites were also estimated to understand the effects of CNT reinforcement in the Al matrix.Microstructural characterization of the nanocomposite reveals that the CNTs are dispersed and embedded in the Al matrix.The experimental results indicate that the incorporation of CNTs into the nano Al matrix results in the increase in hardness and elastic modulus along with a concomitant decrease in the coefficient of thermal expansion The hardness and elastic modulus of the nanocomposite increase by 21%and 20%,respectively,upon CNT addition.The CTE of CNT/A1 nanocomposite decreases to 70%compared with that of nano Al.

Investigation of structural, morphological and electrochemical properties of mesoporous La2CuCoO6 rods fabricated by facile hydrothermal route

This work introduces the facile hydrothermal synthesis of double perovskite La2CuCoO6.X-ray diffraction pattern confirmed the formation of a monoclinic phase with P121/c1 symmetry.Transmission electron microscopy results revealed that the self-assembled porous rods were composed of nanocrystallite aggregates.The estimated specific surface area of these mesoporous rods with an average pore diameter of 6 nm was^41 m^2·g^–1.The presence of ions with oxidation states of La^3+,Cu^2+,and Co^2+/Co^3+on the surface of the mesoporous La2CuCoO6 rods was confirmed by X-ray photoelectron spectroscopic analysis.Via cyclicvoltammetry and chronopotentiometry,the electrode fabricated from the mesoporous La2CuCoO6 rods were found to exhibit pseudocapacitive behavior with a specific capacitance of 259.4 F·g^–1 at a current density of 0.5 A·g^–1.An^89%retention in specific capacitance was achieved after 1000 charge/discharge cycles at a constant current density of4 A·g^–1.

Resistivity Stability of Ga Doped ZnO Thin Films with Heat Treatment in Air and Oxygen Atmospheres

The effect of annealing in air and oxygen on structural, electrical and optical properties of gallium doped ZnO thin films was investigated. The X-ray diffraction patterns showed that the films were highly preferentially oriented along (002) plane. After the heat treatment in air and oxygen environments, the intensity of (002) peak was apparently improved. It was found that heat treatment in air atmospheres lead to increase in surface roughness of the film. The GZO films annealed in oxygen at 673 K exhibited low resistivity of 4.21 × 10–3 Ω.cm, while the resistivity of film annealed in air showed a slightly higher value of 7.14 × 10–3 Ω.cm. In addition to this, all films have good optical transmittance about 80% in the visible region. It is found from the photoluminescence studies that the broad visible emissions in GZO films originated from the intrinsic shallow traps (VZn) and deep level vacancies (ZZi, OZn and Vo)

Synthesis, Characterization and Third Order Non Linear Optical Properties of Metallo Organic Chromophores

The organic imine and their metal complexes were synthesized and characterized by IR, UV and NMR. The third order non linear optical properties of the compounds were investigated. The measurements of second hyperpolarizabilites were performed using single beam Z-scan technique with 8 ns laser pulses. Ligand and its Copper, Zinc and Nickel complexes show good third order non linearity whereas Manganese complex did not show any activity.

Electrical Conductivity, Magnetoconductivity and Dielectric Behaviour of (Mg,Ni)-Ferrite below Room Temperature

We report a comprehensive study of electrical transport properties of stoichiometric (Mg,Ni)-ferrite in the temperature range 77 ≤ T ≤ 300K, applying magnetic field upto 1T in the frequency range 20 Hz-1 MHz. After ball milling of MgO, NiO and ?-Fe2O3 and annealing at 1473K, a (Mg,Ni)-ferrite phase is obtained. The temperature dependency of dc resistivity indicates the prevalence of a simple hopping type charge transport in all the investigated samples. The activation energy decreases by annealing the samples by 1473K. The dc magnetoresistivity of the samples is positive, which has been explained by using wave function shrinkage model. The frequency dependence of conductivity has been described by power law and the frequency exponent ‘s’ is found to be anomalous temperature dependent for ball milling and annealing samples. The real part of the dielectric permittivity at a fixed frequency was found to follow the power law ?/(f,T) ? Tn. The magnitude of the temperature exponent ‘n’ strongly depends on milling time and also on annealing temperature. The dielectric permittivity increases with milling and also with annealing. An analysis of the complex impedance by an ideal equivalent circuit indicates that the grain boundary contribution is dominating over the grain contribution in conduction process.

Study of Duct Characteristics Deduced from Low Latitude Ground Observations of Day-Time Whistler at Jammu

Propagation characteristics of low latitude whistler duct characteristics have been investigated based on day-time measurements at Jammu. The morphogical characteristics of low latitude whistlers are discussed and compared with characteristics of middle and high latitude whistlers. The Max. electron density (Nm) at the height of the ionosphere obtained from whistler dispersion comes out to be higher than that of the background which is in accordance with the characteristics of whistler duct. The equivalent width is found to be close to the satellite observations and the characteristics of whistler duct in low latitude ionosphere are similar to those in middle and high latitude ionosphere. The width of ducts estimated from the diffuseness of the whistler track observed during magnetic storm is found to lie in the range of 50 - 200 Km.

Estimation of Magnetospheric Plasma Parameters from Whistlers Observed at Low Latitudes

Whistler observations during nighttimes made at low latitude Indian ground stations Jammu (geomag. lat., 29°26'N;L = 1.17), Nainital (geomag. lat., 19°1'N;L = 1.16) and Varanasi (geomag. lat., 14°55'N;L = 1.11) are used to deduce electron temperatures and electric field in the vicinity of the magnetospheric equator. The accurate curve fitting and parameter estimation technique are used to compute nose frequency and equatorial electron densities from the dispersion measurements of short whistlers recorded at Jammu, Nainital and Varanasi. In this paper, our aim is to estimate the Magnetospheric electron temperatures and electric field from the dispersion analysis of short whistlers observed at low latitudes by using different methods. The results obtained are in good agreement with the results reported by other workers.

Model dependent analysis of D^(+)_(s)→η^(′)l+v_(l) decays in beyond standard model

Motivated by the recent experimental results of branching fractions for D^(+)_(s)→η^(′)l+v_(l) decays,which deviate from their SM predictions,we hve investigated these decays in W' model and scalar leptoquark model to determine potential signatures of new physics(NP) in semileptonic charm decays induced by c→(s,d)l+v_(l) transitions.Using recent experimental results of branching fractions for semileptonic D meson decays,new coupling parameters are predicted for the aforementioned NP models.Branching fraction,forward-backward asymmetry,and lepton polarization asymmetry are examined by considering the predicted NP coupling parameters.The results of branching fractions in scalar leptoquark model are found very close to the experimental results and exist around the range of 1σ deviation.We presented a comparative study of the NP models to check their sensitivity on these decays.We anticipate that further research on these decays will significantly support our findings.

CuO–TiO_(2) based self-powered broad band photodetector

An efficient room-temperature self-powered,broadband(300 nm–1100 nm)photodetector based on a CuO–TiO_(2)/TiO_(2)/p-Si(100)heterostructure is demonstrated.The CuO–TiO_(2)nanocomposites were grown in a two-zone horizontal tube furnace on a 40 nm TiO_(2)thin film deposited on a p-type Si(100)substrate.The CuO–TiO_(2)/TiO_(2)/p-Si(100)devices exhibited excellent rectification characteristics under dark and individual photoillumination conditions.The devices showed remarkable photo-response under broadband(300–1100 nm)light illumination at zero bias voltage,indicating the achievement of highly sensitive self-powered photodetectors at visible and near-infrared light illuminations.The maximum response of the devices is observed at 300 nm for an illumination power of 10 W.The response and recovery times were calculated as 86 ms and 78 ms,respectively.Moreover,under a small bias,the devices showed a prompt binary response by altering the current from positive to negative under illumination conditions.The main reason behind this binary response is the low turn-on voltage and photovoltaic characteristics of the devices.Under illumination conditions,the generation of photocurrent is due to the separation of photogenerated electron-hole pairs within the built-in electric field at the CuO–TiO_(2)/TiO_(2)interface.These characteristics make the CuO–TiO_(2)/TiO_(2)broadband photodetectors suitable for applications that require high response speeds and self-sufficient functionality.

Progress in doping and crystal deformation for polyanions cathode based lithium-ion batteries

Polyanion-based materials are considered one of the most attractive and promising cathode materials for lithiumion batteries(LIBs)due to their good stability,safety,cost-effectiveness,suitable voltages,and minimal environmental impact.However,these materials suffer from poor rate capability and low-temperature performance owing to limited electronic and ionic conductivity,which restricts their practical applicability.Recent developments,such as coating material particles with carbon or a conductive polymer,crystal deformation through the doping of foreign metal ions,and the production of nanostructured materials,have significantly enhanced the electrochemical performances of these materials.The successful applications of polyanion-based materials,especially in lithium-ion batteries,have been extensively reported.This comprehensive review discusses the current progress in crystal deformation in polyanion-based cathode materials,including phosphates,fluorophosphates,pyrophosphates,borates,silicates,sulfates,fluorosilicates,and oxalates.Therefore,this review provides detailed discussions on their synthesis strategies,electrochemical performance,and the doping of various ions.

Multiple magnetic transitions and magnetocaloric effect of Tb_(4)Coln alloy

We report on the magnetic,magnetocaloric,thermal,and electrical transport properties of Tb_(4)Coln alloy,which crystallizes in two phases,Tb_6Co_(2.1)In_(0.8)(space group Immm)and Tb_(2)In_(0.9)Co_(0.1)(space group P6_(3)/mmc),respectively.The alloy reveals three successive magnetic transitions around T_(1)(163 K),T_(2)(50 K),and T_(3)(29 K),respectively,associated with paramagnetic to ferromagnetic transition and two sequential antiferromagnetic transitions.The low-temperature transition T_(3) follows the first-order magnetic behavior and exhibits the field-induced magnetic transition.Meanwhile,T_(2) and T_(1) are found to be second-order in nature which opens a possibility for hysteresis-free magnetocaloric application.The magnetocaloric properties are determined using different magnetocaloric figures of merits such as-ΔS_(M),ΔT_(ad).RCP,and TEC(10).Additionally,the universal curve behavior in the isothermal entropy change unveils the variation in critical exponents around T_(1) and T_(2) due to the magnetic inhomogeneity in the alloy.Besides,the electrical transport properties of the metallic alloy denote the maximum magnetoresistance of-10%around T_(1).

Enhanced visible-light photocatalytic activity of samarium-doped zinc oxide nanostructures

In the present work,we have synthesized samarium doped zinc oxide nanostructures(Zn1-xSmxO;x=0.00,0.02,0.04 and 0.06) via chemical precipitation method and studied their structural,morphological,optical and photocatalytic properties.X-ray diffraction(XRD) patterns,PL and Raman spectra results indicate that the undoped and Sm-doped ZnO nanostructures are crystallized in a hexagonal wurtzite structure.FESEM images show that the morphology of the sample changes from cubical to hexagonal nanostructures with increase in Sm3+doping concentration.The EDX spectra confirm the incorporation of Sm3+ion in ZnO.The influence of Sm3+doping on the structure,morphology,absorption,emission and photocatalytic activity of ZnO nanostructures were investigated systematically.The addition of Sm3+ion leads to a red shift in the optical energy band gap from 3.19 to 2.67 eV and hence,increases the visible light absorption ability.The presence of E2(H) and E1(LO) modes in microRaman spectra confirms the crystallinity and defects in the samples.The detailed photocatalytic experiments reveal that Sm-doped ZnO nanostructures show the maximum photodegradation efficiency for Methylene blue(MB) dye for x=0.04,i,e.,94.94%,under visible light irradiation.The photocatalytic efficiency improves by 6.98 times when ZnO is doped with rare earth metal ion(Sm3+) and is a potential candidate for practical applications.The investigation demonstrates that as-synthesized nano-sized photocatalysts act as an efficient photocatalyst for the degradation of MB dye.

单壁碳纳米管的力学性能、断裂和屈服行为与其几何形貌的关系(英文)

采用分子动力学模拟研究了单壁碳纳米管的力学特性与其长度、直径及手性的关系。在施加拉伸或压缩载荷时,不同直径的单壁碳纳米管表现出明确的力学性能变化。锯齿型和扶手椅型碳纳米管的拉伸性能与其长度无关,而对于手性碳纳米管来说则稍有变化。所有类型碳纳米管的压缩特性,主要是刚度和临界压应力均随碳纳米管长度的变化而改变。断裂模式因结构不同而异,屈服过程产生纽结、波浪状结构、柱状屈曲、弯曲和扭曲等。