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Experimental evidence for ferromagnetic ordering in isotropic atomically thin two-dimensional crystals has been missing until a bilayer Cr2Ge2Te6, and a three-atom thick monolayer CrI3 are shown to retain ferromagnetic ordering at finite temperatures. Here, we demonstrate successful isolation of a non-van der Waals type ultra-thin nanosheet of FeS2 derived from naturally occurring pyrite mineral (FeS2) by means of liquid-phase exfoliation. Structural characterizations imply that (111) oriented sheets are predominant and is supported theoretically by means of density functional theory surface energy calculations. Spin-polarized density theory calculations further predicted that (111) oriented three-atom thick pyrite sheet has a stable ferromagnetic ground state different from its diamagnetic bulk counterpart. This theoretical finding is evaluated experimentally employing low temperature superconducting quantum interference device measurements and observed an anomalous ferromagnetic kind of behavior., 21 pages, 5 figures

Introduction Imaging is essential for the initial diagnosis and monitoring of the novel coronavirus, which emerged in Wuhan, China. This study aims to assess the insight of radiographers on how the COVID-19 pandemic has affected their work routine and if protective measures are applied. Method A prospective observational study was conducted among radiographers registered in the Cyprus Society of Registered Radiologic Technologists & Radiation Therapy Technologists. A questionnaire composed of 28 multiple choice questions was utilised, and the data analysis was performed using SPSS software with the statistical significance assumed as p-value Results Out of 350 registered radiographers, 101 responses were received. The results showed that there are statistically significant differences regarding the working hours, the feeling of stress, the work effectiveness, the average examination time, the presence of a protocol used among the different workplaces of the participants; a private radiology centre, a private hospital or a public hospital, with a p-value 0.0022, 0.015, 0.027, 0.001, 0.0001 respectively. Also, statistically significant differences were observed in the decontamination methods used for equipment (p-value 0.007), for air (p-value 0.04) and when decontamination takes place (p-value 0.00032) among the different workplaces of the participants. Nonetheless, the majority of radiographers believe that their workplace is sufficiently provided with PPE, cleaning supplies, equipment, and with cleaning personnel and are optimistic regarding the adequacy of these provisions in the next three months. Conclusion This study showed that in the Republic of Cyprus, there are protocols regarding protective measures against COVID-19, and the radiographers are adequately trained on how to face an infectious disease outbreak. However, work is needed in order to develop protocols that reassure the safety of patients and medical personnel while managing the excess workload effectively. Implications for practice This study indicates the importance of applying protective measures and protocols in the radiology departments in order to minimise the spread of the virus.

Monoelemental two-dimensional (2D) materials have attracted significant attention due to their exciting electro-mechanical properties and extreme thinness. However, most of these materials have stable centro-symmetric structures due to same electronegativities of all atoms and lack interesting properties such as piezoelectricity and ferroelectricity. Here we report the existence of piezoelectricity in atomically thin monoelemental α-Tellurium films. DFT calculations reveal that monoelemental few layer α-Tellurene is electrostrictive. However, group theory analysis shows that α-Tellurene belongs to piezoelectric C2 group due to negligible asymmetry and has high anomalous Born effective charges, similar to the traditional perovskite piezoelectric structures. Experimental exploration demonstrates the existence of through thickness piezoelectricity. With single and dual AC resonance tracking piezoelectric force microscopy, piezoelectric coefficient (d33) up to 1 pm/V is observed for the Te ultrathin films. Moderate layer dependent piezoelectricity observed in α-Te films makes it a promising candidate for the realization of atomically thin piezoelectric devices.

Two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures have been proposed as potential candidates for a variety of applications like quantum computing, neuromorphic computing,...

Background and aim The effects of Ramadan fasting on health are a little controversial. The present study is aimed at evaluating the metabolic effects on a group of 517 patients with ≥2 cardiovascular risk factors over a period running from 2012 to 2014. Methods Each patient was assessed at three visits: before, during, and after Ramadan. Demographical, clinical and biological tests were performed at each visit. Results Metabolically, we noted a significant and discrete rise in blood glucose level (+1.2 mmol/L), triglycerides (+0.3 mmol/L), cholesterol (+0.12 mmol/L) and creatinine (+3 µmol/L) during Ramadan. These disturbances decreased significantly after Ramadan. The same variations were observed among diabetics (n=323). However, there was a significant decrease in HbA1c after Ramadan (9.0% vs 7.6%, p

Two-dimensional transition metal dichalcogenides (TMDs) have been proposed for a wide variety of applications, such as neuromorphic computing, flexible field effect transistors, photonics, and solar cells, among others. However, for most of these applications to be feasible, it is necessary to integrate these materials with the current existing silicon technology. Although chemical vapor deposition is a promising method for the growth of high-quality and large-area TMD crystals, the high temperatures necessary for the growth make this technique incompatible with the processes used in the semiconductor industry. Herein, we demonstrate the possibility of low-temperature growth of TMDs, using tungsten selenide (WSe2) as a model, by simply using moisture-assisted defective tungsten oxide (WO3) precursor powders during the growth of these materials. Density functional theory calculations reveal the mechanism by which moisture promotes the defect formation on the precursor crystal structure and how it dictates the reduction of the temperature of the growth. The results were compared with the standard growth at high temperatures and with a precursor mixture with alkali salts to show the high quality of the WSe2 grown at temperatures as low as 550 °C. To conclude, the work improves the understanding of nucleation and growth mechanisms of WSe2 at low temperatures and provides a useful strategy for the growth of TMDs at temperatures required for the back-end-of-line compatibility with current silicon technology.

Hexagonal boron nitride (h-BN) has emerged as a strong candidate for two-dimensional (2D) material owing to its exciting optoelectrical properties combined with mechanical robustness, thermal stability, and chemical inertness. Super-thin h-BN layers have gained significant attention from the scientific community for many applications, including nanoelectronics, photonics, biomedical, anti-corrosion, and catalysis, among others. This review provides a systematic elaboration of the structural, electrical, mechanical, optical, and thermal properties of h-BN followed by a comprehensive account of state-of-the-art synthesis strategies for 2D h-BN, including chemical exfoliation, chemical, and physical vapor deposition, and other methods that have been successfully developed in recent years. It further elaborates a wide variety of processing routes developed for doping, substitution, functionalization, and combination with other materials to form heterostructures. Based on the extraordinary properties and thermal-mechanical-chemical stability of 2D h-BN, various potential applications of these structures are described.

Hybrid/moiré interlayer and intralayer excitons have been realized in twisted two-dimensional transition metal chalcogenides (2D-TMD) due to variation in local moiré potential within a moiré supercell. Though moiré excitons have been detected in TMD heterostructures by macroscopic spectroscopic techniques, their spatial distribution is experimentally unknown. In the present work, using high-resolution scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS), we explore the effect of the twist angle in MoS

International audience; Hybrid/moiré interlayer and intralayer excitons have been realized in twisted two-dimensional transition metal chalcogenides (2D-TMD) due to variation in local moiré potential within a moiré supercell. Though moiré excitons have been detected in TMD heterostructures by macroscopic spectroscopic techniques, their spatial distribution is experimentally unknown. In the present work, using high-resolution scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS), we explore the effect of the twist angle in MoS2/WSe2 heterostructures. We observe weak interaction between the layers at higher twist angles (>5°) and stronger interaction for lower twist angles. The optical response of the heterostructure varies within the moiré supercell, with a lower energy absorption peak appearing in regions with the AA stacking.

Graphite, with many industrial applications, is one of the widely sought-after allotropes of carbon. The sp2 hybridized and thermodynamically stable form of carbon forms a layered structure with strong in-plane carbon bonds and weak inter-layer van der Waals bonding. Graphite is also a high-temperature ceramic, and shaping them into complex geometries is challenging, given its limited sintering behavior even at high temperatures. Although the geometric design of the graphite structure in many of the applications could dictate its precision performance, conventional synthesis methods for formulating complex geometric graphite shapes are limited due to the intrinsic brittleness and difficulties of high-temperature processing. Here, we report the development of colloidal graphite ink from commercial graphite powders with reproducible rheological behavior that allows the fabrication of any complex architectures with tunable geometry and directionality via 3D printing at room temperature. The method is enabled via using small amounts of clay, another layered material, as an additive, allowing the proper design of the graphene ink and subsequent binding of graphite platelets during printing. Sheared layers of clay are easily able to flow, adapt, and interface with graphite layers forming strong binding between the layers and between particles that make the larger structures. The direct ink printing of complex 3D architectures of graphite without further heat treatments could lead to easy shape engineering and related applications of graphite at various length scales, including complex graphite molds or crucibles. The 3D printed complex graphitic structures exhibit excellent thermal, electrical, and mechanical properties, and the clay additive does not seem to alter these properties due to the excellent inter-layer dispersion and mixing within the graphite material., 19 pages, 4 figures

The discovery of ferromagnetism in atomically thin layers at room temperature widens the prospects of 2D materials for device applications. Recently, two independent experiments demonstrated magnetic ordering in two dissimilar 2D systems, CrI3 and Cr2 Ge2 Te6 , at low temperatures and in VSe2 at room temperature, but observation of intrinsic room-temperature magnetism in 2D materials is still a challenge. Here a transition at room temperature that increases the magnetization in magnetite while thinning down the bulk material to a few atom-thick sheets is reported. DC magnetization measurements prove ferrimagnetic ordering with increased magnetization and density functional theory calculations ascribe their origin to the low dimensionality of the magnetite layers. In addition, surface energy calculations for different cleavage planes in passivated magnetite crystal agree with the experimental observations of obtaining 2D sheets from non-van der Waals crystals.

The optical properties of diphosphate LiCrP2O7 compound prepared by the classic ceramic method were recorded at room temperature. Absorption spectrum shows the presence of five characteristics bands related to the octahedral transitions of Cr3+ from ground term 4A2g to excited terms. Crystal field strength and inter electronic repulsion Racah parameters were deduced. The calculated value of direct $$ {E}_g^{\mathrm{direct}} $$ =1.62 eV energy gap has been found using Tauc’s procedure. Besides, the dielectric properties were carried out by impedance spectroscopy at different temperatures (460–700 K). The frequency and temperature dependent of the real e ′ and imaginary e ″ parts of the dielectric constant were discussed. The variation of the frequency power law of the imaginary part of dielectric constant was analyzed in terms of two different conduction mechanisms. Furthermore, the modulus plots can be characterized by the empirical Kohlrausch–Williams–Watts (K.W.W.) function and the obtained values of activation energies deduced from relaxation frequency are in order of E a (I) = 0.49 eV and E a (II) = 0.87 eV.

Hunger and chronic undernourishment impact over 800 million people, which translates to ≈10.7% of the world's population. While countries are increasingly making efforts to reduce poverty and hunger by pursuing sustainable energy and agricultural practices, a third of the food produced around the globe still is wasted and never consumed. Reducing food shortages is vital in this effort and is often addressed by the development of genetically modified produce or chemical additives and inedible coatings, which create additional health and environmental concerns. Herein, a multifunctional bio-nanocomposite comprised largely of egg-derived polymers and cellulose nanomaterials as a conformal coating onto fresh produce that slows down food decay by retarding ripening, dehydration, and microbial invasion is reported. The coating is edible, washable, and made from readily available inexpensive or waste materials, which makes it a promising economic alternative to commercially available fruit coatings and a solution to combat food wastage that is rampant in the world.

Increasing the energy efficiency of buildings has become very pertinent currently. This will be implemented by employing eco-friendly materials such as foam glass. Glass foaming is a process that depends strongly on the foaming mechanism and the initial composition of the mixture. This study deals with the investigation of foam glass properties consisting of recycled bottle glass material, CRT glass and aluminium dross. Experiments were carried out to investigate the thermal behaviour, optimal foaming temperature, density, water absorption, thermal conductivity and compressive strength of the foams. Microstructure and cell size distribution was analyzed as well. Effect of the CRT glass and the aluminium dross on the properties of the foams was evaluated in this paper. Adding aluminium dross decreased the foaming temperature, increased the foaming height and enhanced the compressive strength of the foam glass.

In this research, alumina-zeolite composite materials were synthesised by mechanical activation and oxidation sintering technique. A comprehensive examination of the microstructure of the starting raw materials and the sintered ceramic specimens have been studied via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, several properties were investigated such as volume shrinkage, density, porosity, weight loss and water absorption based on the compositions of the composite specimens, sintering temperature, and microstructure. The authors have found that the raw material compositions and the sintering temperature have great influence in the microstructure and the characteristic of the final prepared ceramic specimens.

Ac electrical conductivity of LiCrP 2 O 7 compound is been investigated by means of impedance spectroscopy measurements over the frequency and temperature ranges of 40 Hz–7 MHz and 460 to 700 K, respectively. The real and imaginary parts of complex impedance are well fitted to two equivalent circuit models. Besides, the nature of frequency dependence of ac conductivity follows the Jonscher's law, while calculated dc conductivity follows Arrhenius behavior with two different activation energies E dc (I) = 0.49 eV for T dc (II) = 0.91 eV for T > 550 K. Actually, the values of activation energies obtained from the impedance E a (I and II), dc conductivity E dc (I and II) and the relaxation time E τ (I and II) are in good agreement, and hence the transport in the titled compound can be described through a simple hopping mechanism, dominated by the motion of Li + ions. The temperature dependence of the power s-factor shows a decrease below 550 ± (5) K with increasing temperature (region I) whereas above 550 ± (5) K (region II), it increases with increasing temperature. An agreement between the experimental and theoretical results are discussed and it is suggested that the ac conductivity can be explained by the correlated barrier hopping (CBH) and non-overlapping small polaron tunneling model (NSPT) in region I and II, respectively.

The NaCrP2O7 compound was prepared by the solid-state reaction method. The formation of a single-phase material was confirmed by the X-ray diffraction studies and found to be a monoclinic system. The electrical properties of this compound have been measured in the temperature range from 523 to 673 K and the frequency range from 209 Hz to 5 MHz. The Nyquist plots are well fitted to an equivalent circuit consisting of a series of combination of grains and grain boundary elements. The ac conductivity of NaCrP2O7 has been analyzed as a function of temperature and frequency. The scaling behavior of the imaginary part of the complex modulus suggests that the relaxation describes the same mechanism at various temperatures. The conductivity and modulus formalisms provide nearly the same activation energies for electrical relaxation of mobile ions suggesting that the ion transport is probably due to a hopping mechanism dominated by the motion of the monovalent ions Na+ along tunnels presented in the structure of the investigated material.

The new detector CHIMERA, in its final 4π configuration, has been installed at Laboratori Nazionali del Sud (LNS) in Catania in January 2003. Beams of different energies ranging from protons to Au ions were delivered by the Tandem and the Super Conducting Cyclotron for nuclear reaction studies, in agreement with the approval of the Scientific Advisory Committee of LNS. Recent experimental results confirm very low energy thresholds of the trigger (below 0.5 MeV/nucleon), ensured within a wide dynamical range. Good characteristics of identification of light charged particles and heavy fragments have been obtained by using three detection techniques: Δ E-E , Δ E -time of flight, and the Pulse-Shape discrimination method. We present results of recent analysis concerning the production of intermediate mass fragments (IMF) in semi-peripheral collisions. Our results combined with theoretical Boltzmann-Nordheim-Vlasov simulations clearly demonstrate the presence of very fast processes of IMF production in the overlapping region of the target and projectile nuclei during re-separation, i.e. in the time scale comparable with the collision time. Evidence for slower, sequential-like production of IMF's is also shown.

In this work, a model based MINLP (mixed integer nonlinear programming) optimisation framework is developed for evaluating boron rejection in a reverse osmosis (RO) desalination process. A mathematical model (for the RO process) based on solution diffusion model and thin film theory is incorporated in the optimisation framework. A superstructure of the RO network is developed which includes two passes: (a) seawater pass containing normal two-stage RO system housing seawater membrane modules and (b) the brackish water pass (BW) accommodating brackish water membrane modules. For fixed freshwater demand, the objective of this work is to demonstrate the effectiveness of the MINLP approach for analyzing and optimizing the design and operation of RO network while attaining desired limit on boron concentration in the freshwater produced. The effect of seasonal variation in seawater temperature and pH on boron removal efficiency is also discussed.

SRAM-based Field Programmable Gate Arrays (SRAM-FPGA) are more and more employed in today's applications. In space and avionic applications their operations might be harmed by occurrence of radiation-induced upsets, or Single Event Upsets (SEU), which require the adoption of mitigation techniques. In these devices the majority of the configuration memory rules the interconnection setting. In devices employing "switch matrix" routing, the density of interconnections in switch arrays seems to be a critical point. The higher the interconnection density (i.e., the higher the number of interconnection segments activated by the same switch matrix), the higher the probability of an upset due to a configuration bit controlling the switch matrix. This paper presents an approach to estimate the SEU sensitivity of programmable interconnections of SRAM-based FPGAs as a function of the density of programmable interconnection points inside device configurable logic blocks. A probabilistic model of the SEU effects in programmable interconnection points of Xilinx SRAM-FPGAs is described. The application of the proposed approach to a set of sample designs is illustrated.

Objective: This article concerns evaluation of the sensitivity, specificity and accuracy of FNAB for pre-surgical diagnosis of benign and malignant lesions of major and minor salivary glands of patients treated in the Department of Head and Neck Surgery of Erasto Gartner Hospital. Methods: This retrospective study analyzed medical records from January 2006 to December 2011 from patients with salivary gland lesions who underwent preoperative FNAB and, after surgical excision of the lesion, histopathological examination. Results: The study had a cohort of 130 cases, but 34 cases (26.2%) were considered unsatisfactory regarding cytology analyses. Based on the data, sensitivity was 66.7% (6/9), specificity was 81.6% (71/87), accuracy was 80.2% (77/96), the positive predictive value was 66,7% (6/9) and the negative predictive value was 81.6% (71/87). Conclusion: Despite the high rate of inadequate samples obtained in the FNAB in this study the technique offers high specificity, accuracy and acceptable sensitivity.

The design of reverse osmosis (RO) network for desalination for a wide range of salinity and seawater temperature is considered here. We start with a flexible superstructure that contains all possible alternatives of a potential RO network and refine the network during the synthesis using model based optimization technique. The synthesis problem is posed to find out an optimal RO network which will minimize the total annualized cost consisting of capital costs (costs of sea water pre-treatment, pump, turbine and membrane modules) and operating costs (pumping energy, chemicals, maintenance and membrane replacement) while fulfilling a given fresh water demand and quality. The problem results in a mixed-integer non-linear programming (MINLP) problem due to the presence of both integer and non-integer decision variables. Outer approximation algorithm within gPROMS software is used to solve the optimization problem. The results revealed that the feed salinity and temperature have significant impact on the RO network design and operation.

This paper deals with the job shop problem of simultaneous scheduling of production operations and preventive maintenance tasks. To solve this problem, we develop an elitist multi-objective genetic algorithm that provides a set of Pareto optimal solutions minimising the makespan and the total maintenance cost. A deep study was made to choose the best encoding, operators, and the different probabilities. Some lower bounds of the adopted criteria are developed. The computational experiments carried out on a set of published instances validate the efficiency of the proposed algorithm.