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•A novel hydrothermal route has been developed for the synthesis of MoS2/graphene composite with controllable structures.•The effects of Mo4+-to-C precursor ratios and crystalline ...time on properties of MoS2/graphene were investigated by FESEM, HRTEM, XRD, FTIR, Raman spectroscopy, HAADF-STEM/EDS and HXPES.•The memristive properties of the MoS2/graphenenanocomposite were presented.
In this study, a novel hydrothermal route has been developed for the synthesis of MoS2/graphene composite with controllable structures, in which ammonium molybdatetetrahydrate, as-prepared graphene oxide (GO), and thioacetamide were used as staring materials. Effects of Mo4+-to-C precursor ratios and crystalline time on the structures, components and morphologies of MoS2/graphene were investigated. MoS2/graphene samples were characterized using XRD, FESEM, HRTEM, FTIR, Raman spectroscopy, HAADF-STEM/EDS, HXPES and electrical measurements. The results show that petal-like MoS2 nanostructures with ultrathin petals (~1–10 layers) and coexistence of 1T- and 2H-MoS2 phases can be synthesized on graphene surface in a short time (~2 h). Comparison of crystallization conditions, we found that the crystallization time had a significant effect on the size of the MoS2 nanopetals. The shorter the reaction time is, the thinner the petal-like MoS2 nanoscale is. On the other hand, by adjusting the ratios of Mo4+to C (denoted as: MoS2/C (1:2), MoS2/C (3:2), MoS2/C (2.5:1) and MoS2/C (3:1)), different MoS2/graphene architectures including “sandwich-liked”, “layer–by–layer” and “anchored” can be obtained. On the basis of these results, a possible growth mechanism of MoS2nanopetals on GO was proposed. Interestingly, the as-synthesized material depicts its memristive behavior through the Volt-Ampere characteristics, suggesting a potential application in logic memory devices.
Hollow LaFeO3 (LFO-HS) was synthesized by a facile hydrothermal method with the use of cetyltrimethylammonium bromide. Its structural, morphological, microstructural and textual characterizations ...were performed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption analysis. The gas-sensing performance of LFO-HS sensor was studied towards different gases, including ammonia (NH3), ethanol (C2H5OH), acetone (CH3COCH3), and liquefied petroleum gas (LPG). The LFO-HS sensor exhibited p-type gas sensing behavior and enhanced sensing performance towards ethanol gas as compared with bulk LaFeO3 sensor. A rapid, high, and stable response was seen at 300 °C. Meanwhile, a linear response and low limit of detection (1 ppb) to ethanol was observed. After the investigation on sensitivity to different reducing gases, our results revealed that the LFO-HS sensor exhibited good selectivity to ethanol and suggested it being a promising sensor candidate for future practical use in trace ethanol detection.
•Hollow core and porous shell LaFeO3 (LFO-HS) was synthesized by a surfactant-assisted hydrothermal method.•The enhancement of ethanol gas-sensing characteristic of LFO-HS relating to its structural and mophological properties.•Trace-level detection limit of ethanol (down to 1 ppb) of 6-lay LFO-HS gas sensor.•Gas sensing mechanism based on p-type semiconductor properties, generated from La vacancies.
Job satisfaction is an important factor affecting job performance and turnover of healthcare workers, especially hospital pharmacists. Nevertheless, limited studies have reported this issue in the ...context of Vietnam.
To help maintain the quality and size of the limited hospital pharmacy workforce in Vietnam, especially in the Mekong Delta area, this study investigated the job satisfaction of hospital pharmacists, and the associated factors, in Vinh Long province, a representative province in the central Mekong Delta.
A cross-sectional survey was conducted, recruiting hospital pharmacists working in all 17 province/district-affiliated healthcare facilities across Vinh Long province, Vietnam, between August and September 2022.
Among the 235 survey participants (representing a response rate of 97.1%), 189 pharmacists (80.4%) reported that they were satisfied with their job. Working conditions, leadership styles, and benefits were factors found to significantly influence job satisfaction. Pharmacists who had worked in the field for 3-5 years (OR = 3.752, 95% CI = 1.036-13.595), more than 5 years (OR = 6.361, 95% CI = 2.264-17.875), did not have additional duties besides their primary responsibilities (OR = 2.046, 95% CI = 1.005-4.163), and worked in a private healthcare facility (OR = 12.021, 95% CI = 1.470-98.316), were significantly more likely to be satisfied with their job.
Most hospital pharmacists were satisfied with their current job. To further improve job satisfaction in this population, further improvements to working conditions are necessary.
•Carbon dioxide and cyclopentane mixed hydrate formation in presence of salts.•Equilibrium data for CO2-CP hydrate in presence of NaCl-KCl (1.75–1.75%, MgCl2 (3.5–10%)and CaCl2 (4–10%).•Three ...thermodynamic model comparison with absolute average deviation within 0.2 K.•Dissociation enthalpy calculation of inhibited mixed hydrate system.
The applications of clathrate hydrates on carbon dioxide capture and desalination is an attractive and growing subject within the hydrate community. While many promoters exists to overcome the numerous issues of hydrate-based technologies (mostly how to mild the operating conditions and improve the kinetics), there is a need to find a guest that could be recovered easily. That is why cyclopentane (CP), an organic molecule not miscible into water that can form hydrates under atmospheric pressure at 7 °C, has been studied widely in the literature. However, its behavior in forming mixed hydrates with CO2 in presence of salts is still not well understood. This work is an effort to investigate the thermodynamics of mixed CO2/CP hydrates to fulfill the gap in this field from a thermodynamic point of view. In this effort, new equilibrium data of mixed CO2/CP hydrates in the presence of salts (NaCl-KCl, MgCl2, CaCl2 which are among the main factors of hard water) have been obtained under different concentrations and pressures. Final dissociation points and as well as intermediate metastable points were obtained. Furthermore, thermodynamic consistency tests have been performed on our data and literature data to discuss their reliability. This test is important to question the idea of thermodynamic equilibrium since we suspect from a previous work the formation of several hydrate structures. Finally, three modeling approaches were considered: van der Waals and Platteeuw (vdW-P) approach, Hu-Lee-Sum (HLS) correlation, and ice melting point method derived from HLS proposition. Results showed a greater inhibition effect of cation Ca2+ compared to Mg2+ and that vdW-P method can predict equilibrium temperature within 0.2 °C uncertainty.
Interconnected macroporous calcium phosphate has attracted attention as an artificial bone substitute as well as a scaffold for tissue engineering. In this investigation, a setting reaction between ...α-tricalcium phosphate (α-TCP) spheres and an acidic calcium phosphate solution (0.2mol/L monocalcium phosphate monohydrate – 0.1mol/L phosphoric acid) was studied to assess the feasibility of fabricating fully interconnected macroporous calcium phosphate. When 1.3mm-diameter α-TCP spheres were exposed to an acidic calcium phosphate solution, brushite (dicalcium phosphate dihydrate) was formed on the surface of the α-TCP spheres. The precipitated brushite crystals interlocked with one another and bridged the α-TCP spheres, resulting in a 10min setting reaction at 37°C that produced fully interconnected macroporous calcium phosphate. The resultant calcium phosphate macroporous structure had a porosity of 49.7±2.5% and an average pore size of 312±160μm.
In this paper, we report on synthesizing xonotlite, calcium silicate hydrate (CSH), via a hydrothermal reaction using rice husk from the Mekong Delta, Vietnam. The rice husks were burnt at 1000 °C ...for 3 h. Grey rice husk ash was collected, then mixed with Ca(OH)2 at a Ca/Si molar ratio of 1 : 1. This was followed by a hydrothermal reaction at 180 °C for 24 h and 48 h to obtain the xonotlite mineral. Before and after adsorption, 3-mm xonotlite pellets were thoroughly characterized using X-ray diffractometry (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and ultraviolet-visible (UV-VIS) spectroscopy. This material has potential application in chromium(III) removal during a chrome-plating process. The adsorption efficiency of the 3-mm pellet samples reached more than 76 % after 12 h.
Attributed to its bioactivity, osteoconductivity, and chemical compositions similarly to those of human bones, hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is a well-known material suitable for bone graft ...applications. To achieve physical and mechanical properties desired for the practical applications, microstructure of the HAp specimen needs to be controlled. This study therefore aimed at fabricating freeze-cast hydroxyapatite specimens with the porosity, pore sizes and compressive strength with acceptable values for the applications. Effects of solids loadings and silica addition on compressive strength were also examined in this study. Experimental results indicated that enhanced strength could be obtained in the specimens prepared from slips with higher solids loadings. The results also revealed that the HAp specimens achieved average porosity, pore sizes, and compressive strength in the ranges of 43.3–72.8%, 94.2–128.4 µm, and 1.29–29.35 MPa, respectively. The highest compressive strength was evident in the specimens prepared from silica-added slip with 35 vol% solids loading. The pH value of simulated body fluid solution was relatively stable upon sample submersion. Slight increase of specimen weight and formation of apatite layer were observed. The findings suggested that the specimens could be potential candidates for biomedical applications.
Medical pure titanium (Ti) shows excellent chemical stability and mechanical properties in clinical uses, but its initial fixation with host bone, when implanted, is usually delayed owing to the ...bioinert Ti surface. In this study, we fabricate the hydroxyapatite (HA)-coated titanium by three steps reactions: (1) to form an activated O2− layer by immersing Ti substrate into an alkaline solution such as NaOH; (2) the O2− bonds with Ca2+ to form Ca–O–Ti bonding, in which O plays the part of bridge materials between Ca and Ti substrate and (3) the conversion of Ca–O–Ti samples to HA-coated Ti samples by immersion into Na2HPO4 2 M at 180 °C for 48 h using hydrothermal methods. The effect of different phosphate solutions (NaH2PO4 2 M and Na2HPO4 2 M solution) and hydrothermal treatment time (24 and 48 h) on the characteristic of hydroxyapatite coating titanium substrate is also investigated using the optical microscope, thin film XRD and SEM/EDX. The HA-coated Ti samples fabricated by immersion into Na2HPO4 2 M at 180 °C for 48 h show fiber HA covering Titan substrate with a diameter varying from 0.1 to 0.3 µm. These HA-coated Ti samples can be regarded as promising multifunctional biomaterials.
Although the concept of translanguaging is not new, little is
known about how it is employed and viewed by Vietnamese English
as a Foreign Language (EFL) teachers in both public and private
...institutions. By investigating how EFL secondary teachers in the
public and private sectors employ translanguaging in language
schools and their perceptions, this convergent mixed-method study
bridged the gap in current literature. Following the collection of
questionnaires from 32 secondary school teachers in a district of
Hanoi and four semi-structured interviews with 04 survey
participants, descriptive analysis was used to examine the
quantitative data while thematic analysis was used to analyze the
qualitative data. The merged results showed that most teachers in
both sectors had positive opinions on translanguaging and thought it
was crucial for scaffolding students’ learning, especially for
cognitive purposes (e.g. to explain difficult grammar/ vocabulary)
due to the importance of grammar and vocabulary for exam
preparation while using translanguaging for affective purposes was
found unimportant by most participants. Also, teachers in public
schools reported using translanguaging more frequently than those
in private schools due to the private institutions’ policy. The study
continues to confirm results of previous studies, supporting
translanguaging use in EFL classrooms. It also argues that
translanguaging should not be prohibited but included strategically
in language teaching, calling for reconsideration in language policy
from private schools. Some implications were offered and further
research is needed to generate more insights.
Today, oil and gas fields gradually become mature with a high amount of water being produced (water cut (WC)), favoring conditions for gas hydrate formation up to the blockage of pipelines. The ...pressure drop is an important parameter which is closely related to the multiphase flow characteristics, risk of plugging and security of flowlines. This study developed a model based on flowloop experiments to predict the relative pressure drop in pipelines once hydrate is formed in high water cutsystems in the absence and presence of AA-LDHI and/or salt. In this model, the relative pressure drop during flow is a function of hydrate volume and hydrate agglomerate structure, represented by the volume fraction factor (Kv). This parameter is adjusted for each experiment between 1.00 and 2.74. The structure of the hydrate agglomerates can be predicted from the measured relative pressure drop as well as their impact on the flow, especially in case of a homogeneous suspension of hydrates in the flow.
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