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Background: Food safety issues are a major concern for the globe and food related diseases impose a great burden on public health in both developed and developing countries. Objectives: This research work is aimed at evaluation of the understanding of the food handler’s regarding their food handling knowledge and practices and contributing factors behind those practices of the selected hospital cafeterias in Dhaka city, Bangladesh. Study Design: The study was cross-sectional in nature. Methods: Purposive sampling method was used for selection of both hospital cafeterias and food handlers. A total of 8 hospital cafeterias were selected and 120 food handlers were assessed for knowledge and practice status. Data were collected through face-to-face interview of the food handlers by using a pretested questionnaire and observation checklist. SPSS version 25 statistical packages was used for data management and analysis. Percentage, chi-square test and logistics regressions were used to analyze the data. Results: Among the 120 food handlers, 58 (48.4%) of them aged below 20 years and all (100%) were male. About two-third of the food handlers (70%) had educational level below secondary level. Only 46 (38.3%) of them had training regarding food preparation and handling. 76 (63.3%) of them had heard about food borne diseases. Majority (62.50%) of the food handlers had poor knowledge score. Practice score revealed that majority, 71.67% (86) of food handlers observed were poor in maintaining food handling practices. Univariate analysis showed that training status (P=0.000), educational level (P=0.000) and monthly income (P=0.031) had significant impact on food handling practices. Multivariate logistic regression showed that training status (P=0.000, AOR=0.049, 95% CI =0.011, 0.225) and educational level (P=0.006) had significant impact on food handling practice. There were significant (P=0.002) relationship between knowledge score and food handling score of the food handlers of selected hospitals cafeterias of Dhaka city, Bangladesh. Conclusion: Majority of food handlers had poor food safety knowledge and poor food handling practices. The influential factors behind poor food handling practices of the food handlers were poor knowledge, poor educational status and poor training status. Provision of training and food safety and health education programs can improve the situation. Key words: Food safety knowledge; food handling practices; hospital cafeterias; Dhaka city; Bangladesh

We report the measurement of efficient charge-to-spin conversion at room temperature in Weyl semimetal/ferromagnet heterostructures with both oxidized and pristine interfaces. Polycrystalline films of the Weyl semimetal, TaAs, are grown by molecular beam epitaxy on (001) GaAs and interfaced with a metallic ferromagnet (Ni$_{0.8}$Fe$_{0.2}$). Spin torque ferromagnetic resonance (ST-FMR) measurements in samples with an oxidized interface yield a spin torque efficiency as large as $\xi_{\mathrm{FMR}}=0.45\pm 0.25$ for a 8 nm Ni$_{0.8}$Fe$_{0.2}$ layer thickness. By studying ST-FMR in these samples with varying Ni$_{0.8}$Fe$_{0.2}$ layer thickness, we extract a damping-like torque efficiency as high as $\xi_{\mathrm{DL}}=1.36\pm 0.66$. In samples with a pristine (unoxidized) interface, the spin torque efficiency has opposite sign to that observed in oxidized samples ($\xi_{\mathrm{FMR}}=-0.27\pm 0.14$ for a 5 nm Ni$_{0.8}$Fe$_{0.2}$ layer thickness). We also find a lower bound on the spin Hall conductivity ($424 \pm 110 \frac{\hbar}{e}$ S/cm) which is surprisingly consistent with theoretical predictions for the single crystal Weyl semimetal state of TaAs.

Norepinephrine (NE) neuromodulation plays a role in diverse non-specific physiological and cognitive functions including wakefulness, arousal, and cognitive performance. NE modulation of neuronal responses in the cerebral cortex has been proposed to mediate improved task-specific behavior by enhancing sensory processing. However, the sensory-specific NE contribution on performance remains unknown. We directly tested the role of NE-mediated neuromodulation of sensory signals on perceptual performance in non-human primates doing visual spatial attention tasks. We found that NE neurons in the locus coeruleus (LC) respond selectively to an attended stimulus. Optogenetically enhancing the sensory-specific responses of LC-NE neurons improved the monkeys’ sensory discrimination in a spatially selectively way, without affecting motor processing. These findings identify a specific contribution of NE neuromodulation of sensory representations to selective attention and performance.One-Sentence SummaryOptogenetic activation of monkey locus coeruleus causes a strong and spatially selective improvement in visual sensitivity.Graphical abstractElevation of phasic norepinephrine signal by optogenetic stimulation of locus coeruleus in non-human primates selectively improves attentional performance that attributes to enhanced sensory sensitivity.

Synthesis of a pentasil‐type zeolite with ultra‐small few‐unit‐cell crystalline domains, which we call FDP (few‐unit‐cell crystalline domain pentasil), is reported. FDP is made using bis‐1,5(tributyl ammonium) pentamethylene cations as structure directing agent (SDA). This di‐quaternary ammonium SDA combines butyl ammonium, in place of the one commonly used for MFI synthesis, propyl ammonium, and a five‐carbon nitrogen‐connecting chain, in place of the six‐carbon connecting chain SDAs that are known to fit well within the MFI pores. X‐ray diffraction analysis and electron microscopy imaging of FDP indicate ca. 10 nm crystalline domains organized in hierarchical micro‐/meso‐porous aggregates exhibiting mesoscopic order with an aggregate particle size up to ca. 5 μm. Al and Sn can be incorporated into the FDP zeolite framework to produce active and selective methanol‐to‐hydrocarbon and glucose isomerization catalysts, respectively., A simple di‐quaternary ammonium cation was used as structure‐directing agent to prepare few‐unit‐cell (ca. 10 nm) MFI type zeolite catalysts and adsorbents with a wide range of composition (pure silica, aluminosilicate and stannosilicate). The SDA design was selected based on simple heuristic arguments regarding contributions of its structural elements to early crystal growth characteristics of MFI.

Task demands can differentially engage two fundamental attention components: selectivity (spatial bias) and effort (total nonselective attentional intensity). The relative contributions and interactions of these components in modulating neuronal signals remain unknown. We recorded V4 neurons while monkeys’ spatially selective attention and effort were independently controlled by adjusting either task difficulty or reward size at two locations. Neurons were robustly modulated by either selective attention or effort. Notably, increasing overall effort to improve performance at a distant site reduced neuronal responses even when performance was unchanged for receptive field stimuli. This interaction between attentional selectivity and effort was evident in single-trial spiking and can be explained by divisive normalization of spatially distributed behavioral performance at the single-neuron level. Changing motivation using task difficulty or reward produced indistinguishable effects. These results provide a cellular-level mechanism of how attention components integrate to modulate sensory processing in different motivational contexts.

Two-dimensional (2D) perovskites with alternating cations in the interlayer space (ACI) represent a new type of structure with different physical properties compared to the more common Ruddlesden–P...

In recent years, there has been a surge in research efforts to utilize organic−inorganic lead halide perovskites (OLHPs) in optoelectronic devices (e.g., concentrator photovoltaics) requiring high ...

This study was driven for analyzing the drinking water quality of three upazillas at Noakhali district in Bangladesh. Nine different areas drinking water samples were collected from three upazilas (sadar-upazila, kabirhat upazila, Chatkhil upazila). Physical & chemical parameters of the collected samples like pH, electrical conductivity, salt, TDS, chloride-ion, iron content were measured and microbial parameters like Total Viable Bacterial Count (TVBC), Most Probable Number (MPN) of coliforms, E. coli, Pseudomonas, Klebsiella, Enterobacter aerogenes were also detected. All the parameters were compared with WHO drinking water quality standard ranges to understand the condition of drinking water in these areas. This study showed the pH of Chatkhil upazila was comparatively lower (6.18) than other upazilas. Electrical conductivity was also lower (252.1 μS/cm) in Chatkhil than other upazilas. Salt volume was comparatively higher (554.33 ppm) in sadar upazila sample than in others. TDS of all upazila samples were in an acceptable range. Chloride-ion was very much higher (7326.33 mg/L) in upazila-sadar. Iron content was mostly (3 mg/L) in Chatkhil upazila. Total bacterial load was comparatively higher (7.13 × 106 CFU/mL) in Kabirhat upazila. Most Probable Number (MPN) of Coliforms were comparatively higher (24.67 number of coliforms/100mL) in upazila-sadar than others. This study also showed the water samples that were collected almost all were contaminated by E. coli bacteria without supply water in upazila-sadar. As a result, water was not suitable for drinking. Water purification is very urgently needed for saving people from water-borne diseases. So necessary steps should immediately be taken for purifying the sources of drinking water.

We report the hydrothermally enhanced hydrolysis of polyacrylonitrile (PAN) in neutral water, which generates photoluminescent polymers with low unsaturation degrees. Despite the hydrophobic nature of PAN, the product can be dissolved in water at a high concentration (≥100 g/L). The product exhibits complete absence of alkenes or aromatic structures, and photoluminescence originates from newly formed N- and O-containing groups. The presence of both

Zeolite nanosheets can be used for the fabrication of low-defect-density, thin, and oriented zeolite separation membranes. However, methods for manipulating their morphology are limited, hindering progress toward improved performance. We report the direct synthesis (i.e., without using exfoliation, etching, or other top-down processing) of thin, flat MFI nanosheets and demonstrate their use as high-performance membranes for xylene isomer separations. Our MFI nanosheets were synthesized using nanosheet fragments as seeds instead of the previously used MFI nanoparticles. The obtained MFI nanosheets exhibit improved thickness uniformity and are free of rotational and MEL intergrowths as shown by transmission electron microscopy (TEM) imaging. The nanosheets can form well-packed nanosheet coatings. Upon gel-free secondary growth, the obtained zeolite MFI membranes show high separation performance for xylene isomers at elevated temperature (e.g., p -xylene flux up to 1.5 × 10 −3 mol m −2 s −1 and p -/ o -xylene separation factor of ~600 at 250°C).

This work explores the use of chiral cobalt oxide thin film electrocatalysts for the oxygen evolution reaction and examines how their spin polarization properties might be used to control electroch...

Mesoporous silica is often employed as a coating material in core-shell nanoparticles to decrease the possibility of sintering or aggregation of the core particles. In this work, we discovered a surprising morphological transformation during the sulfidation and regeneration (oxidation) of core-shell CuO@mSiO2 materials designed for H2S capture. Although CuS cores were still encapsulated within the silica shells after in situ sulfidation, hollow silica shells formed during the regeneration step as CuO leached out of the shell and aggregated into larger particles. The successful sulfidation of pristine CuO@mSiO2 was facilitated by the restraining effect of silica shells on lattice growth from CuO into CuS, and the mesopores allowed for volume expansion. The phase and morphology changes during the regeneration (oxidation) process leading to the hollow shells were investigated by X-ray diffraction and transmission electron microscopy. It was observed that the cores remained encaged during the disproportionation of CuS to Cu2S, which is the first step in the oxidation of CuS. However, voids were generated when Cu2S was oxidized and reacted with water generated from the condensation of silica. A possible mechanism for this transformation involves the outward diffusion of copper ions through the mesoporous silica, leading to the migration of core particles. This migration was further accelerated by the elevated temperature in the regeneration process and promoted by the formation of the copper sulfate hydroxide through the reaction with water. This work provides key insights into the chemical stability of such core-shell structures under the influence of diffusion-driven structural transformations.

Black arsenic (BAs) is a van der Waals layered material with a puckered honeycomb structure and has received increased interest due to its anisotropic properties and promising performance in devices. Here, crystalline structure, thickness-dependent dielectric responses, and ambient stability of BAs nanosheets are investigated using STEM imaging and spectroscopy. Atomic-resolution HAADF-STEM images directly visualize the three-dimensional structure and evaluate the degree of anisotropy. STEM-EELS is used to measure the dielectric response of BAs as a function of the number of layers. Finally, BAs degradation under different ambient environments is studied highlighting high sensitivity to moisture in the air., Comment: 26 pages, 5 figures

Zeolite MFI is a widely used catalyst and adsorbent that also holds promise as a thin-film membrane. The discovery of nanometre-thick two-dimensional (2D) MFI nanosheets has facilitated methods for thin-film zeolite fabrication that open new horizons for membrane science and engineering. However, the crystal structure of 2D-MFI nanosheets and their relationship to separation performance remain elusive. Using transmission electron microscopy, we find that one- to few-unit-cell-wide intergrowths of zeolite MEL exist within 2D-MFI. We identify the planar distribution of these 1D or near-1D-MEL domains, and show that a fraction of nanosheets have high (~25% by volume) MEL content while the majority of nanosheets are MEL-free. Atomistic simulations show that commensurate knitting of 1D-MEL within 2D-MFI creates more rigid and highly selective pores compared to pristine MFI nanosheets, and permeation experiments show a separation factor of 60 using an industrially relevant (undiluted 1 bar xylene mixture) feed. Confined growth in graphite is shown to increase the MEL content in MFI nanosheets. Our observation of these intergrowths suggests strategies for the development of ultra-selective zeolite membranes. Two-dimensional zeolite MFI nanosheets show ultra-selective separation of xylene isomers, but it was not known why this occurs. Here, using electron microscopy and atomistic simulation, it is shown that one-dimensional intergrowths of zeolite MEL enable selectivity by formation of more rigid pores.

Kelvin-probe measurements on ferromagnetic thin film electrodes coated with self-assembled monolayers of chiral molecules reveal that the electron penetration from the metal electrode into the chiral molecules depends on the ferromagnet’s magnetization direction and the molecules’ chirality. Electrostatic potential differences as large as 100 mV are observed. These changes arise from the applied oscillating electric field, which drives spin-dependent charge penetration from the ferromagnetic substrate to the chiral molecules. The enantiospecificity of the response is studied as a function of the magnetization strength, the magnetization direction, and the handedness and length of the chiral molecules. These new phenomena are rationalized in terms of the chiral-induced spin selectivity (CISS) effect, in which one spin orientation of electrons from the ferromagnet penetrates more easily into a chiral molecule than does the other orientation. The large potential changes (>kT at room temperature) manifested here imply that this phenomenon is important for spin transport in chiral spintronic devices and for magneto-electrochemistry of chiral molecules.

Organic lead halide perovskite (OLHP) nanocrystals (NCs) have paved the way to advanced optoelectronic devices through their extraordinary electrical and optical properties. However, understanding of the light-induced complex dynamic phenomena in OLHP NCs remains a subject of debate. Here we used wide field microscopy and time-resolved spectroscopy to correlate the local changes in photophysics and the dynamical behavior of photocarriers. We demonstrate that light-induced brightening of the photoluminescence from the formamidinium lead bromide NC films is related to the film preparation condition and reduction of trap density. The density of trap states is reduced via halide ion migration from interstitial position. Our femtosecond transient absorption study identifies transient Stark effect due to the generation of hot carriers. Because of slow carrier trapping, Auger recombination through many-body carrier-carrier interactions dominates over trion recombination. This work presents unprecedented insights into the light-driven processes enabling better device design in the future.

Here, we quantify the effect of an external magnetic field (β) on the oxygen evolution reaction (OER) for a cobalt oxide|fluorine-doped tin oxide coated glass (CoO

Cobalt oxides have long been understood to display intriguing phenomena known as spin-state crossovers, where the cobalt ion spin changes vs. temperature, pressure, etc. A very different situation was recently uncovered in praseodymium-containing cobalt oxides, where a first-order coupled spin-state/structural/metal-insulator transition occurs, driven by a remarkable praseodymium valence transition. Such valence transitions, particularly when triggering spin-state and metal-insulator transitions, offer highly appealing functionality, but have thus far been confined to cryogenic temperatures in bulk materials (e.g., 90 K in Pr1-xCaxCoO3). Here, we show that in thin films of the complex perovskite (Pr1-yYy)1-xCaxCoO3-{\delta}, heteroepitaxial strain tuning enables stabilization of valence-driven spin-state/structural/metal-insulator transitions to at least 291 K, i.e., around room temperature. The technological implications of this result are accompanied by fundamental prospects, as complete strain control of the electronic ground state is demonstrated, from ferromagnetic metal under tension to nonmagnetic insulator under compression, thereby exposing a potential novel quantum critical point., Comment: 35 pages, 7 figures

The rapid discovery of two-dimensional (2D) van der Waals (vdW) quantum materials has led to heterostructures that integrate diverse quantum functionalities such as topological phases, magnetism, and superconductivity. In this context, the epitaxial synthesis of vdW heterostructures with well-controlled interfaces is an attractive route towards wafer-scale platforms for systematically exploring fundamental properties and fashioning proof-of-concept devices. Here, we use molecular beam epitaxy to synthesize a vdW heterostructure that interfaces two material systems of contemporary interest: a 2D ferromagnet (1T-CrTe

Flexibly switching attentional strategies is crucial for adaptive behavior in changing environments. Depending on the context, task demand employs different degrees of the two fundamental components of attention– attentional selectivity (preferentially attending to one location in visual space) and effort (the total non-selective intensity of attention). Neuronal responses in the visual cortex that show modulation with changes in either selective attention or effort are reported to partially represent motivational aspect of the task context. The relative contributions and interactions of these two components of attention to modulate neuronal signals and their sensitivity to distinct motivational drives are poorly understood. To address this question, we independently controlled monkeys’ spatially selective attention and non-selective attentional intensity in the same experimental session during a novel visual orientation change detection task. Attention was controlled either by adjusting the relative difficulty of the orientation changes at the two locations or by the reward associated with stimuli at two locations while simultaneously recording spikes from populations of neurons in area V4. We found that V4 neurons are robustly modulated by either selective attention or attentional intensity. Notably, as attentional selectivity for a neuron’s receptive field location decreased, its responses became weaker, despite an increase in the animal’s overall attentional intensity. This strong interaction between attentional selectivity and intensity could be identified in single trial spike trains. A simple divisive normalization of spatially distributed attention performances can explain the interaction between attention components well at the single neuron level. The effects of attentional selectivity and attentional intensity on neuronal responses were the same regardless of whether the changes were motivated by reward or task difficulty. These results provide a detailed cellular-level mechanism of how fundamental components of attention integrate and affect sensory processing in varying motivational and stimulus contexts.

ispartof: JOURNAL OF RAMAN SPECTROSCOPY vol:52 issue:12 pages:2338-2347 status: published

We report spin-to-charge and charge-to-spin conversion at room temperature in heterostructure devices that interface an archetypal Dirac semimetal, Cd3As2, with a metallic ferromagnet, Ni0.80Fe0.20 (permalloy). The spin-charge interconversion is detected by both spin torque ferromagnetic resonance and ferromagnetic resonance driven spin pumping. Analysis of the symmetric and anti-symmetric components of the mixing voltage in spin torque ferromagnetic resonance and the frequency and power dependence of the spin pumping signal show that the behavior of these processes is consistent with previously reported spin-charge interconversion mechanisms in heavy metals, topological insulators, and Weyl semimetals. We find that the efficiency of spin-charge interconversion in Cd3As2/permalloy bilayers can be comparable to that in heavy metals. We discuss the underlying mechanisms by comparing our results with first principles calculations.