Tunnelling Characteristics of Stone-Wales Defects in Monolayers of Sn and Group-V Elements

Topological defects in ultrathin layers are often formed during synthesis and processing, thereby, strongly influencing their electronic properties . In this paper, we investigate the role of Stone-Wales (SW) defects in modifying the electronic properties of the monolayers of Sn and group-V elements. The calculated results find the electronic properties of stanene (monolayer of Sn atoms) to be strongly dependent on the concentration of SW-defects e.g., defective stanene has nearly zero band gap (~ 0.03 eV) for the defect concentration of 2.2 x 10^13 cm^-2 which opens up to 0.2 eV for the defect concentration of 3.7 x 10^13 cm^-2. In contrast, SW-defects appear to induce conduction states in the semiconducting monolayers of group-V elements. These conduction states act as channels for electron tunnelling, and the calculated tunnelling characteristics show the highest differential conductance for the negative bias with the asymmetric current-voltage characteristics. On the other hand, the highest differential conductance was found for the positive bias in stanene. Simulated STM topographical images of stanene and group-V monolayers show distinctly different features in terms of their cross-sectional views and distance-height profiles which can serve as fingerprints to identify the topological defects in the monolayers of group-IV and group-V elements in experiments.Comment: 18 pages, 5 figures, 1 tabl

An Efficient Lightweight Provably Secure Authentication Protocol for Patient Monitoring Using Wireless Medical Sensor Networks

The refurbishing of conventional medical network with the wireless medical sensor network has not only amplified the efficiency of the network but concurrently posed different security threats. Previously, Servati and Safkhani had suggested an Internet of Things (IoT) based authentication scheme for the healthcare environment promulgating a secure protocol in resistance to several attacks. However, the analysis demonstrates that the protocol could not withstand user, server, and gateway node impersonation attacks. Further, the protocol fails to resist offline password guessing, ephemeral secret leakage, and gateway-by-passing attacks. To address the security weaknesses, we furnish a lightweight three-factor authentication framework employing the fuzzy extractor technique to safeguard the user’s biometric information. The Burrows-Abadi-Needham (BAN) logic, Real-or-Random (ROR) model, and Scyther simulation tool have been imposed as formal approaches for establishing the validity of the proposed work. The heuristic analysis stipulates that the proposed work is impenetrable to possible threats and offers several security peculiarities like forward secrecy and three-factor security. A thorough analysis of the preexisting works with the proposed ones corroborates the intensified security and efficiency with the reduced computational, communication, and security overheads

Giant pressure sensitivity in piezo/ferro-electric ceramics

We report the fabrication of single-phase polycrystalline Pb0.85Bi0.10(Zr0.52Ti0.48)O-3 (PBiZT) ceramic which shows large polarization, i.e., similar to 40 mu C cm(-2) and piezoelectric coefficients similar to 130 pC N-1 and giant linear change in capacitive reactance and dielectric properties with increasing and decreasing pressure in the range of 1 kHz to 5 MHz. Nearly 70% change in dielectric constant and 56% change in capacitive reactance were obtained in the pressure range of 20-200 MPa, which makes it suitable for applications as a capacitive pressure sensor/gauge. The sensitivity of the device is calculated as 0.66 MPa-1 and 18.2 MPa-1 at 1 MHz and 5 MHz, respectively, which is the highest ever reported value so far for any bulk polycrystalline ceramic. The compressive stress of the device was tested according to the standard test method as a function of linear and volumetric strain, which yields the Young's modulus, Bulk modulus, and Poisson's ratio of the device. These values were further utilized to calculate actual stress in the sample and energy density using ANSYS software, which indicates at least four orders smaller pressure in the sample compared to the applied pressure

Two Dimensional Allotropes of Arsenene with Wide Range of High and Anisotropic Carrier Mobility

Considering the rapid development of experimental techniques for fabricating 2D materials in recent years, various monolayers are expected to be experimentally realized in the near future. Motivated by the recent research activities focused on the honeycomb arsenene monolayers, stability and carrier mobility of non-honeycomb and porous allotropic arsenene are determined using first principles calculations. In addition to five honeycomb structures of arsenene, a total of eight other structures are considered in this study. An extensive analysis comprising energetics, phonon spectra and mechanical properties confirms that these structures are energetically and dynamically stable. All these structures are semiconductors with a broad range of band gap varying from ~1 eV to ~2.5 eV. Significantly, these monolayer allotropes possess anisotropic carrier mobilities as high as several hundred cm^{2}V^{-1}s^{-1} which is comparable with the well-known 2D materials such as black phosphorene and monolayer MoS_{2}. Combining such broad band gaps and superior carrier mobilities, these monolayer allotropes can be promising candidates for the superior performance of the next generation nanoscale devices. We further explore these monolayer allotropes for photocatalytic water splitting and find that arsenene monolayers have potential for usage as visible light driven photocatalytic water splitting.Comment: 31 pages, 8 figures, 3 table

Comparison of freeze-thaw and sonication cycle-based methods for extracting AMR-associated metabolites from Staphylococcus aureus

Emerging antimicrobial resistance (AMR) among Gram-positive pathogens, specifically in Staphylococcus aureus (S. aureus), is becoming a leading public health concern demanding effective therapeutics. Metabolite modulation can improve the efficacy of existing antibiotics and facilitate the development of effective therapeutics. However, it remained unexplored for drug-resistant S. aureus (gentamicin and methicillin-resistant), primarily due to the dearth of optimal metabolite extraction protocols including a protocol for AMR-associated metabolites. Therefore, in this investigation, we have compared the performance of the two most widely used methods, i.e., freeze-thaw cycle (FTC) and sonication cycle (SC), alone and in combination (FTC + SC), and identified the optimal method for this purpose. A total of 116, 119, and 99 metabolites were identified using the FTC, SC, and FTC + SC methods, respectively, leading to the identification of 163 metabolites cumulatively. Out of 163, 69 metabolites were found to be associated with AMR in published literature consisting of the highest number of metabolites identified by FTC (57) followed by SC (54) and FTC + SC (40). Thus, the performances of FTC and SC methods were comparable with no additional benefits of combining both. Moreover, each method showed biasness toward specific metabolite(s) or class of metabolites, suggesting that the choice of metabolite extraction method shall be decided based on the metabolites of interest in the investigation

Effect of elevated CO2 and temperature on growth parameters of pea (Pisum sativum L.) crop

Global warming is predicted to have negative effect on plant growth due to the damaging effect of high temperature on plant development. The field experiment was conducted during 2014-15 to study effect of elevated CO2 and temperature on growth parameters of pea (Pisum sativum L.) crop in order to check the effect of climatechange on vegetable crops. Effect was studied under four conditions i.e. Open Top Chambers, T1: OTC - elevated CO2550±10 ppm; T2: OTC -elevated CO2 550±10 ppm and temperature 1°C; T3: OTC - ambient CO2 and temperature (reference) and T4: natural condition. Maximum plant height at 50 % flowering was recorded in T1 (84.29cm) at elevated CO2 which differed significantly with T2 (79.47cm) at elevated CO2 and temperature, T3 (73.60cm) at ambient CO2 and temperature and natural condition (70.73cm). Minimum days to 50 per cent flowering were recorded in plants growing under T2 (68.56 days). Maximum pollen viability was recorded in T1 (77.42%) followed by T3 (76.36%), T4 (74.65%) and T2 (69.97%). Internode length of plants grown under T1 was maximum (7.01cm) followed by T2 (6.68cm), T3 (6.00cm) and T4 (5.05cm). Elevated temperature and CO2 had significant effects on growth and development in vegetables. Overall, growth parameters of pea crop were affected positively by elevated CO2 whereas under interaction effect of elevated CO2 and temperature these positive effects of CO2 were offset by elevated temperature effect and hampered the growth of pea crop which interns can affect the yield and quality of crop under changing climate scenario

Low-frequency dielectric processes in deformed helix ferroelectric liquid crystals

A low-frequency dielectric relaxation mode in deformed helix ferroelectric liquid crystal (DHFLC) has been observed at the interface of strongly rubbed substrates and DHFLC material which may find applications in low power consumption FLC devices. The surface-induced dielectric relaxation process at the interface of DHFLC and substrate is called the partially unwound helical mode (p-UHM) due to the unwinding of the helical structure at this interface. After investigation of the material under various parameters such as temperature, variation of the amplitude of probing ac voltage and dc bias voltage, the relaxation frequency of p-UHM is found to be shifted towards Goldstone mode and merged with it. The relaxation frequency of Goldstone mode is found to decrease, whereas the relaxation frequency of p-UHM process increases with the increase in temperature of DHFLC. Finally, both the modes merge and the resultant relaxation frequency is found to be lower than Goldstone mode in SmC* phase. It seems that phason mode and partial helical unwinding mode are coupled together due to dipole moment that is resulting in a new relaxation frequency. p-UHM process is significant for low-power displays and non-displays applications like a part of sensor where weak electric signal is required to be realized without pre-amplification

Improved sorghum hybrids with grain mold resistance

Sorghum (Sorghum bicolor) is the fifth most important cereal crop globally after wheat (Triticum aestivum), rice (Oryza sativa), maize (Zea mays) and barley (Hordeum vulgare) with multiple uses as food, feed, fodder and fuel. It has a great potential in the gluten-free food market. Globally it is grown on over 43 million ha predominantly in tropical Africa and India. It is also grown in temperate areas (Americas, Europe and Australia) as a feed crop. In the tropics, sorghum is faced with a hostile environment, where unreliable rainfall, poor soils, pests, diseases and parasitic weeds constantly exert harsh selection pressure. India has the largest area (8.5 million ha) under sorghum and 45% of this area is in rainy season while postrainy season sorghum accounts for the remaining area