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This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered films. By combining experimental evidences and theoretical results, we find out that hydrogen located at oxygen vacancy sites (HO) is the main factor gives rise to increase simultaneously mobility and carrier concentration which has not been mentioned before. Introducing appropriate hydrogen content during sputtering not only results in crystalline relaxation but also supports doping Al into ZnO, increasing carrier concentration and electron mobility in the film. First principles calculations confirmed hydrogen substitutional stability for oxygen vacancy, significantly reducing electron conductivity effective mass and hence increasing electron mobility. In particular, 0.8% hydrogen partial pressure ratio achieved 61 cm2V−1s−1 maximum electron mobility, optical transmittance above 82% in visible and near-infrared regions, and 2 × 1020 cm−3 carrier concentrations for H Al co-doped ZnO film. These values approach ideal electrical and optical properties for transparent conducting oxide films. The presence of one maximum electron mobility was attributed to competition between increasing mobility due to restoring effective electron mass and hydrogen passivation of native defects, and decreased electron mobility due to electron-phonon scattering.

The aim of this study is to figure out advantages and applications of infrared rays system in hospitals, at home and in industry. Methodology that authors use is empirical research and practices and experiences in infrared rays system applications in emerging markets such as Vietnam. Research Results find out that danger for infrared products users as it goes with high temperature, however there are many advantages such as kitchen stoves, temperature guns. Last but not least, infrared rays products has other applications in hospitals. Finally, we suggest there are more further researches on applications of infrared rays products in future. Risk management also need for infrared rays products applications.

Machine Learning (ML) solutions are nowadays distributed, according to the so-called server/worker architecture. One server holds the model parameters while several workers train the model. Clearly, such architecture is prone to various types of component failures, which can be all encompassed within the spectrum of a Byzantine behavior. Several approaches have been proposed recently to tolerate Byzantine workers. Yet all require trusting a central parameter server. We initiate in this paper the study of the ``general'' Byzantine-resilient distributed machine learning problem where no individual component is trusted. We show that this problem can be solved in an asynchronous system, despite the presence of $\frac{1}{3}$ Byzantine parameter servers and $\frac{1}{3}$ Byzantine workers (which is optimal). We present a new algorithm, ByzSGD, which solves the general Byzantine-resilient distributed machine learning problem by relying on three major schemes. The first, Scatter/Gather, is a communication scheme whose goal is to bound the maximum drift among models on correct servers. The second, Distributed Median Contraction (DMC), leverages the geometric properties of the median in high dimensional spaces to bring parameters within the correct servers back close to each other, ensuring learning convergence. The third, Minimum-Diameter Averaging (MDA), is a statistically-robust gradient aggregation rule whose goal is to tolerate Byzantine workers. MDA requires loose bound on the variance of non-Byzantine gradient estimates, compared to existing alternatives (e.g., Krum). Interestingly, ByzSGD ensures Byzantine resilience without adding communication rounds (on a normal path), compared to vanilla non-Byzantine alternatives. ByzSGD requires, however, a larger number of messages which, we show, can be reduced if we assume synchrony., This is a merge of arXiv:1905.03853 and arXiv:1911.07537; arXiv:1911.07537 will be retracted

Increasing waste generation and the absence of a formal recycling industry are exacerbating the inadequacy of Construction and Demolition Waste (CDW) management in Hanoi, Vietnam. This study assesses potential CDW recycling in Hanoi by estimating the prospective supply of and demand for CDW recycling plants and evaluating their likely costs and benefits. Supply of concrete waste was calculated based on the weight-per-construction-area method whilst demand for recycled concrete aggregates (RCA) was determined by estimating the amount of aggregates for road construction in Hanoi from 2013 to 2017. Two potential models of CDW recycling plants were considered: a stationary plant and a mobile plant, with capacities of 1,000 and 360 tons/day, respectively. Our findings reveal that demand for RCA exceeds waste concrete supply, suggesting a promising market for RCA. Positive Net Present Value and Internal Rate of Return values of the stationary plant indicate its feasibility as an investment option. Meanwhile, the introduction of mobile recycling plants might require governmental intervention to internalize recycling positive externalities. Supporting policies might include a combination of a virgin material tax, green public procurement, and quality standard development.

Background Cashew nut shell is a by-product of cashew (Anacardium occidentale) production, which is abundant in many developing countries. Cashew nut shell liquor (CNSL) contains a functional chemical, cardanol, which can be converted into a hydroxyoxime. The hydroxyoximes are expensive reagents for metal extraction. Methods CNSL-based oxime was synthesized and used to extract Ni, Co, and Mn from aqueous solutions. The extraction potential was compared against a commercial extractant (LIX 860N). Results All metals were successfully extracted with pH0.5 between 4 and 6. The loaded organic phase was subsequently stripped with an acidic solution. The extraction efficiency and pH0.5 of the CNSL-based extractant were similar to a commercial phenol-oxime extractant. The metals were stripped from the loaded organic phase with a recovery rate of 95% at a pH of 1. Conclusions Cashew-based cardanol can be used to economically produce an oxime in a simple process. The naturally-based oxime has the economic potential to sustainably recover valuable metals from spent lithium-ion batteries. Graphic abstract

Despite pioneering as the holy grail in photocatalysts, abundant reports have demonstrated that g-C3N4 performs poor photocatalytic activity due to its high recombination rate of photo-induced charge carriers. Many efforts have been conducted to overcome this limitation in which the semiconductor–semiconductor coupling strategies toward heterojunction formation were considered as the easiest but the most effective method. Herein, a one-pot solid-state reaction of thiourea and sodium molybdate as precursors at different temperatures under N2 gas was applied for preparing composites of MoS2/g-C3N4. The physicochemical characterization of the final products determines the variation in contents of components (MoS2 and g-C3N4) via the increase of synthesis temperature. The enhanced photocatalytic activity of the MoS2/g-C3N4 composites was evaluated by the degradation of Rhodamine B in an aqueous solution under visible light. Therein, composites synthesized at 500 °C showed the best photocatalytic performance with a degradation efficiency of 90%, much higher than that of single g-C3N4. The significant improvement in photocatalytic performance is attributed to the enhancement in light-harvesting and extension in photo-induced charge carriers’ lifetime of composites which are originated from the synergic effect between the components. Besides, the photocatalytic mechanism is demonstrated to well-fit into the S-scheme pathway with apparent evidences.

The paper describes e-Health system based on telemedicine platform and GRID layer model. We identify the currently isolated hospital subsystems that should be integrated. Telemedicine platform was proposed that was designed to enable secure management and analysis of patient data and DICOM images in a grid environment. The platform provides doctors the capacity to upload and query medical information stored over distributed servers. It was built also for sharing data between remote hospitals to help doctors in diagnosis. We propose the software components and Grid infrastructure for implementation of the Telemedicine platform and show some results of our implementation in the hospitals.

This is the first report on the optical and resistance properties of copper aluminum oxide thin films for applications as thermal infrared imagers. The deposition of these films was investigated under three series of reactive magnetron sputtering conditions. Structural characterization identified the P63mmc hexagonal crystalline structure of CuAlO2 although the 150- to 350-nm thick films were in a non-stoichiometric CuAlxOy ratio. The thermal coefficient of resistance of the CuAlxOy films was measured to be in the range 1.7–2.2%/K and the resistivity ranged from 0.3 to 1.0 Ω cm with n-type nature. To explain the low indirect bandgap value of the CuAlxOy films, a type-I band alignment bulk heterojunction between CuAlO2 and Cu2O is proposed. This provides an effective method to decrease the resistivity and increase the thermal coefficient of resistance. From their optical characterization, a refractive index of 2.27 ± 0.07 was deduced, thus favoring the CuAlxOy films for antireflection coating in the long infrared wavelength region. A micromachining process of CuAlxOy micro-bridges was demonstrated with well-defined shapes at a pixel pitch of 25 μm. These findings pave the way for the future development of high-performance thermal infrared imagers.

A combination of biomass-derived activated carbon and nano-carbonaceous materials has been considered as a sustainable approach to developing the highly electro-adsorptive electrode for desalination by capacitive deionization (CDI) technology. These composites can propose many enormous advantages such as non-toxicity, eco-friendly, high conductivity, and scalability. This work aimed to fabricate the composite coconut-shell-derived activated carbon/carbon nanotubes electrode with low CNTs content (1 wt%) for desalination. The nitrogen adsorption/desorption demonstrates the decrease of surface area of AC/CNTs-1% composite as compared to AC-pristine due to the blocking of micropores of AC. The SEM images evidenced good connection between CNTs and AC particles, where the fibrils of CNTs were featured as the electrical bridges to improve the electron transfer between the AC particles in the electrode structure. Comparison of the CDI performance of AC/CNTs-1% composite electrode in two regimes (batch mode and single-pass mode) in Ragone plot showed that the single-pass mode provided the essential factors of salt absorption capacity and average salt adsorption rate which shifted toward much upper and right regions, indicating the superior desalination performance. At the operation of 1.2 V, the batch mode and single-pass mode can deliver the salt absorption capacity of 10.93 mg g−1 and 11.97 mg g−1, respectively. The durability test of our CDI system in single-pass mode showed a stable performance on 100 cycles with the energy consumption of 0.284 kWh m−3 which is suitable for large-scale CDI applications using the renewable energy sources.

Aconitum carmichaelii Debx. is a medicinal plant that contains a variety of valuable medicinal substances, including flavonoids, alkaloids, and polysaccharides. Flavonoids are important substances because of their antioxidant, antiproliferative, and anticancer effects, but the flavonoid content in A. carmichaelii is low. Flavonoid 3′5′-hydroxylase (F3′5′H) is a key enzyme that catalyzes the final reactions in flavonoid biosynthesis in A. carmichaelii. Therefore, overexpressing the gene encoding of the F3′5′H enzyme to increase the flavonoid content in A. carmichaelii is a new direction in medicinal plant research strategies. In this work, the results of Agrobacterium tumefaciens–mediated genetic transformation of uidA and AcF3′5′H in A. carmichaelii plants, expression analysis of AcF3′5′H, and production of transgenic A. carmichaelii plants have been presented. Out of 180 transformed samples, 24 transgenic A. carmichaelii plants developed normally under greenhouse conditions. The results of PCR analysis of 15 transgenic A. carmichaelii plants showed that eight transgenic plants contained the AcF3′5′H transgene. Using electrophoresis SDS-PAGE, western blot, and ELISA techniques, we identified the expression of AcF3′5′H protein (rAcF3′5′H) in three transgenic plants. The rAcF3′5′H protein content of transgenic plants ranged from 0.2083 μg μL−1 (transgenic line T0-6) to 0.2507 μg μL−1 (T0-4). The highest concentrations of flavonoids, 773.50 ± 12.87, 661.73 ± 2.85, and 761.61 ± 9.10 μg g−1, were found in transgenic lines T0-4, T0-6, and T0-13, respectively. These values were higher than those of the non-transformed plants (wild-type). Our results demonstrate that compared with non-transgenic plants, overexpression of AcF3′5′H significantly increased the AcF3′5′H protein content in transgenic plants and the total flavonoid content in transgenic lines T0-4, T0-6, T0-13, from 39.13 to 63.63%. This is the first report of genetic transformation and an analysis of the expression enhancement of F3′5′H in the A. carmichaelii plant.

Effects of silver nanoparticles (AgNPs) on somatic embryogenesis and plantlets with rhizome of Panax vietnamensis were presented in this study. The highest number of somatic embryos (140) was obtained on MS medium containing 1 mg/L 2.4-D, 0.5 mg/L NAA, 0.2 mg/L Kin and 1.6 mg/L AgNPs. Plantlets with rhizome growth enhanced on SH medium supplemented with 1 mg/L NAA and 1.2 mg/L AgNPs and limited the ethylene gas content in the culture flasks. A low concentration of ethylene gas (0.92 ppm) stimulated plantlets with rhizome growth and development, and provided positive effect on the formation and quality of plantlets. The rhizome size of the plantlets in 1.2 mg/L AgNPs treatment was larger than those in the control without AgNPs. Plantlets acclimatized on the soilless substrate were higher survival rate (93.65%) as compared to the control (44.44%) after one year in the greenhouse. In particular, the rhizome saponin content was doubled compared with that in the planlets without AgNPs after 4-year planting in the greenhouse. These results may be scaled up for micropropagation of this important medicinal plant. AgNPs improved somatic embryogenesis. AgNPs enhanced plantlets with rhizome. AgNPs limited ethylene accumulation during micropropagation. AgNPs increased the survival rate of plantlets with rhizome in the greenhouse. AgNPs increased saponin content of plantlets with rhizome.

Design and synthesis of low bandgap (LBG) polymer donors is inevitably challenging and their processability from a non-halogenated solvent system remains a hurdle to overcome in the area of high-performance polymer solar cells (PSCs). Due to a high aggregation tendency of LBG polymers, especially diketopyrrolopyrrole (DPP)-based polymers coupled with bithiophenes in the polymer backbones, their widespread adoption in non-halogenated solvent-processed PSCs has been limited. Herein, a novel LBG DPP-based polymer, called PDPP4T-1F with asymmetric arrangement of fluorine atom, has been successfully synthesized and showed an outstanding power conversion efficiency (PCE) of 10.10% in a single-junction fullerene-based PSCs. Furthermore, an impressive PCE of 13.21% has been achieved in a tandem device from a fully non-halogenated solvent system, which integrates a wide bandgap PDTBTBz-2F polymer in the bottom cell and LBG PDPP4T-1F polymer in the top cell. The achieved efficiency is the highest value reported in the literature to date in fullerene-based tandem PSCs. We found that a uniformly distributed interpenetrating fibril network with nano-scale phase separation and anisotropy of the polymer backbone orientation for efficient charge transfer/transport and suppressed charge recombination in PDPP4T-1F-based PSCs led to outstanding PCEs in single and tandem-junction PSCs.

Landslides are considered to be a significant risk to life and property all over the world in general and in Vietnam in particular. Spatial prediction of landslides is required to reduce the landsl...

This study investigated the occurrence, distribution of several additive brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and some novel brominated flame retardants (NBFRs) in urban indoor dust collected from ten inner districts of Hanoi, Vietnam to assess the contamination status, emission sources, as well as their associated human exposure through indoor dust ingestion and health risks. Total concentrations of PBDEs and NBFRs in indoor dust samples ranged from 43 to 480 ng g-1 (median 170 ng g-1) and from 56 to 2200 ng g-1 (median 180 ng g-1), respectively. The most abundant PBDE congener in these dust samples was BDE-209 with concentrations ranging from 29 to 360 ng g-1, accounting for 62.6-86.5% of total PBDE levels. Among the NBFRs analyzed, decabromodiphenyl ethane (DBDPE) was the predominant compound with a mean contribution of 98.6% total NBFR amounts. Significant concentrations of DBDPE were detected in all dust samples (median 180 ng g-1, range 54-2200 ng g-1), due to DBDPE as a substitute for deca-BDE. Other NBFRs such as 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromoethylbenzene (PBEB) and 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) were found at very low levels. Based on the measured BFR concentrations, daily intake doses (IDs) of PBDEs and NBFRs via dust ingestion at exposure scenarios using the median and 95th percentile levels for both adults and children were calculated for risk assessment. The results showed that the daily exposure doses via dust ingestion of all compounds, even in the high-exposure scenarios were also lower than their reference dose (RfD) values. The lifetime cancer risks (LTCR) were much lower than the threshold level (10-6), which indicated the acceptable health risks resulting from indoor BFRs exposure for urban residents in Hanoi.

In this study, the generation of hydrogen from synthesis gas through the pyrolysis of modified Water Hyacinth (Eichhornia Crassipes) biomass was investigated. The modified Water Hyacinth feedstocks were prepared by immersing its dried samples into Iron Chlorides (III) solution under different concentrations (0.5, 1, 1.5, and 2 M). After a 60 min pyrolysis at 540 °C, each created biochar sample also generates a different volume of synthesis gas depending on the properties of the feedstock that were applied to the system. In that manner, it is clear that the value of ferric chloride concentration plays an important role in the generating of synthesis gas. The study indicates that the increase of ferric chloride concentration may also raise the production of synthesis gas, and the amount of hydrogen as well. The result indicates that the 2WH sample (with 2 M of ferric chloride catalyst) exhibited the highest conversion for Water Hyacinth pyrolysis volatiles, with 280 mL of total gas production (42% of hydrogen included, 23% of carbon dioxide, 22% of carbon monoxide and 7% of methane). Therefore, the main objective of the work is achieved by revealing the influence of the metal catalyst over the production of gases via the pyrolysis. On the other hand, the fact that the Water Hyacinth can be utilized effectively also contributes greatly to the matter of environmental betterment.

In this work, we consider a fractional diffusion equation with nonlocal integral condition. We give a form of the mild solution under the expression of Fourier series which contains some Mittag-Leffler functions. We present two new results. Firstly, we show the well-posedness and regularity for our problem. Secondly, we show the ill-posedness of our problem in the sense of Hadamard. Using the Fourier truncation method, we construct a regularized solution and present the convergence rate between the regularized and exact solutions.

Unsubstituted and methylated polycyclic aromatic hydrocarbons (22 PAHs and 17 Me-PAHs) were examined in surface sediments collected from the Red River and four inner-city rivers of Hanoi City, Vietnam. Concentrations of total PAHs and Me-PAHs ranged from 52 to 920 (median 710) and from 70 to 2600 (median 1000) ng/g dry weight in samples of dry and wet seasons, respectively. Significant correlation was observed between total PAHs and organic carbon contents (Spearman's ρ = 0.782; p

Diketopyrrolopyrrole (DPP) is one of the most used moieties in D–A conjugated polymers for high-performance π-extended conjugated polymer-based organic solar cells. The combination of 1,4-diketo-3,6-dithienylpyrrolo[3,4-c]pyrroles (DTDPPs) and the donor moieties 10-(4-((2-ethylhexyl)oxy)phenyl)-10H-phenothiazine (M1), 10-(4-((2-ethylhexyl)oxy)phenyl)-10H-phenoxazine (M2), has not been reported yet. In this report, novel low-bandgap D–A conjugated polymer derivatives including DTDPP, phenothiazine and phenoxazine were successfully synthesized via direct (hetero) arylation polymerization with in the yields of 40.94–60.77%. The obtained D–A conjugated polymers named poly(3,6-Di(2-thienyl)pyrrolo[3,4-c]pyrrole-1,4-dione)-alt-(10-(4-((2-ethylhexyl)oxy) phenyl)-10H-phenothiazine) (P1) and poly(3,6-Di(2-thienyl)pyrrolo[3,4-c]pyrrole-1,4-dione)-alt-(10-(4-((2-ethylhexyl)oxy) phenyl)-10H-phenoxazine) (P2) exhibited a wide range of absorption spectrum in visible light region and have a low bandgaps of 1.4–1.5 eV, as well as thermal stabilities, these D–A conjugated polymers are very promising as activated polymeric materials for organic solar cells (OSCs).

Hybrid composite TiO2/reduced graphene oxide (TiO2/rGO) is considered as a potential photoanode for dye-sensitized solar cells (DSSC) due to their excellent charge transport. This work aimed to prepare the composite TiO2/rGO from TiO2 and GO via a facile reduction step by ascorbic acid and annealing step at 450 °C. Incorporation 1%wt rGO into TiO2 photoanode can boost the overall performance of DSSC with the photocurrent of 13.5 mA/cm2 and the efficiency of 6.1% which is 37% enhanced than the bare TiO2 photoanode. The XPS, Raman spectroscopy and FT–IR results revealed the formation of the chemical bonding titania–carbon in composites TiO2/rGO-1% by ex-situ preparation. The interfacial charge transfer through chemical bonds significantly improves the photoelectrons transport and suppresses the recombination of electron holes in TiO2 structure.

Ectopic expression of Glycine max two-component system member GmHP08 in Arabidopsis enhanced drought tolerance of transgenic plants, possibly via ABA-dependent pathways. Phosphorelay by two-component system (TCS) is a signal transduction mechanism which has been evolutionarily conserved in both prokaryotic and eukaryotic organisms. Previous studies have provided lines of evidence on the involvement of TCS genes in plant perception and responses to environmental stimuli. In this research, drought-associated functions of GmHP08, a TCS member from soybean (Glycine max L.), were investigated via its ectopic expression in Arabidopsis system. Results from the drought survival assay showed that GmHP08-transgenic plants exhibited higher survival rates compared with their wild-type (WT) counterparts, indicating better drought resistance of the former group. Analyses revealed that the transgenic plants outperformed the WT in various regards, i.e. capability of water retention, prevention of hydrogen peroxide accumulation and enhancement of antioxidant enzymatic activities under water-deficit conditions. Additionally, the expression of stress-marker genes, especially antioxidant enzyme-encoding genes, in the transgenic plants were found greater than that of the WT plants. In contrary, the expression of SAG13 gene, one of the senescence-associated genes, and of several abscisic acid (ABA)-related genes was repressed. Data from this study also revealed that the ectopic expression lines at germination and early seedling development stages were hypersensitive to exogenous ABA treatment. Taken together, our results demonstrated that GmHP08 could play an important role in mediating plant response to drought, possibly via an ABA-dependent manner.

Blasting plays a fundamental role in rock fragmentation, and it is the first preparatory stage in the mining extraction process. However, its undesirable effects, mostly ground vibration, can cause severe damages to the surroundings, such as cracks/collapses of buildings, instability of slopes, deformation of underground space, affect underground water, to name a few. Therefore, the primary purpose of this study was to predict the intensity of ground vibration induced by mine blasting operations with high accuracy, aiming to reduce the severe damages to the surroundings. A novel artificial neural network (ANN)-based cuckoo search optimization (CSO), named as CSO–ANN model, was proposed for this aim based on 118 blasting events that were collected at a quarry mine in Vietnam. Besides, stand-alone models, such as ANN, support vector machine (SVM), tree-based ensembles, and two empirical equations (i.e., USBM and Ambraseys), were considered and developed for comparative evaluation of the performance of the proposed CSO–ANN model. Afterwards, they were tested and validated based on three blasting events in practical engineering. The results revealed that the CSO algorithm significantly improved the performance of the ANN model. In addition, the comparative results showed that the accuracy of the proposed hybrid CSO–ANN model was superior to the other models with MAE (mean absolute error) of 0.178, RMSE (root-mean-squared error) of 0.246, R2 (square of the correlation coefficient) of 0.990, VAF (variance accounted for) of 98.668, and a20-index of 1.0. Meanwhile, the other models only yielded performances in the range of 0.257–0.652 for RMSE, 0.932–0.987 for R2, 20.942–98.542 for VAF and 0.227–0.955 for a20-index. The findings also indicated that explosive charge per borehole has a special relationship with ground vibration intensity. It should be considered and used instead of total explosive charge per blast in some cases, especially for the empirical models.

This work proposed a novel double-bath-type sonoreactor to demonstrate the possibility of applying ultrasound power for simultaneous production of gaseous fuels with degradation of Rhodamine B (RhB). The developed double-bath-type sonoreactor allows concentrating the energy of the ultrasonic waves to a limited region and, consequently allows the acoustic intensity in there to be increased approximately 30-fold compared to that can be created in a normal ultrasonic bath at the same applied power. The effect of acoustic intensity, temperature of water bath, static and bubbling argon atmosphere, initial RhB concentration, and dissolved gases on the sonochemical activity both in terms of RhB degradation and gaseous fuel productions were fully investigated. The possible pathways for the simultaneous production of gaseous fuels with degradation of RhB were elucidated. Sonochemical degradation of RhB was successfully analysed by Langmuir-Hinshelwood-type kinetics.

Two new cadinane sesquiterpenes, cadinoschanes A and B (1 and 2), one new norlignan, lignanoschane A (6) along with seven known compounds, hibiscone B (3), 7β-O-β-glucopyranosyl bombaxone (4), 2,7β,8β-trihydroxy trans-calamenene 7-O-β-D-glucopyranoside (5), clemastanin A (7), (−)-3,4,3′,4′-tetrahydroxy-9,7′β-epoxylignano-7β,9′-lactone (8), N-trans-feruloyl tyramine (9), and methyl (3R)-3-[(3R)-3-{(3R)-3-hydroxybutanoyloxy} butanoyloxy} butanoate (10) were isolated from Abelmoschus moschatus subsp. tuberosus (Span.) Borss. Waalk. Their structures were determined on the basis of extensive spectroscopic methods, including 1D, 2D NMR and MS data and comparing experimental CD with theoretical CD calculations. Compounds 3 and 9 showed significant α-glucosidase inhibitory activity with IC50 values of 121.7 ± 3.9 and 4.3 ± 0.5 μg/mL, respectively, compared to those of a positive control, acarbose with IC50 value of 183.5 ± 12.2 μg/mL.

This paper proposes a High Performance Cuckoo Search Algorithm (HPCSA) for determining suitable operation parameters of the optimal wind-hydro-thermal system scheduling (OWHTSS) problem. The objective of the problem is to reach the lowest electricity generation cost of thermal power plants (TPPs) and wind power plants (WPPs) while exactly meeting all constraints of TPPs, WPPs and hydroelectric plants (HEPs). HPCSA is formed by applying improvements on the two main techniques of original Cuckoo Search Algorithm (CSA) to cover CSA’ drawbacks such as searching random solution spaces, always using two random solutions for getting a jumping step and suffering from slow convergence. HPCSA accompany with CSA, Adaptive CSA (ACSA), Snap-Drift CSA (SDCSA) and Water Cycle Algorithm (WCA) are run for solving four test systems in which the largest and complicated system is comprised of four TPPs, four HEPs and two WPPs with the uncertain wind feature. The result comparisons indicate that HPCSA is superior to applied and previous methods, and other modified versions of CSA in the literature in terms of better cost, higher stability, faster search ability and higher success rate. As a result, it leads to a conclusion that HPCSA is a strong metaheuristic algorithm for solving OWHTSS problem.

We consider the model Y = X + ξ where Y is observable, ξ is a noise random variable with density f ξ , X has an unknown mixed density such that P ( X = X c ) = 1 − p , P ( X = a ) = p with X c being continuous and p ∈ ( 0 , 1 ) , a ∈ R . Typically, in the last decade, the model has been widely considered in a number of papers for the case of fully known quantities a , f ξ . In this paper, we relax the assumptions and consider the parametric error ξ ∼ σ N ( 0 , 1 ) with an unknown σ > 0 . From i.i.d. copies Y 1 , … , Y m of Y we will estimate ( σ , p , a , f X c ) where f X c is the density of X c . We also find the lower bound of convergence rate and verify the minimax property of established estimators.

In the present paper, a nonlocal problem for semilinear fractional diffusion equations with Riemann-Liouville derivative is investigated. By applying Banach fixed point theorem combined with some techniques on Mittag-Leffler functions, we establish some results on the existence, uniqueness, and regularity of the mild solutions of our problem in some suitable spaces. In addition, we show that the convergence of mild solution as the parameter tends to zero and present some numerical examples to illustrate the proposed method.

The influence of zeolite support materials and their impact on CH4 oxidation activity was studied utilizing Pd supported on H-beta and H-SSZ-13. A correlation between CH4 oxidation activity, Si/Al ratio (SAR), the type of zeolite framework, reduction-oxidation behaviour, and Pd species present was found by combining catalytic activity measurements with a variety of characterization methods (operando XAS, NH3-TPD, SAXS, STEM and NaCl titration). Operando XAS analysis indicated that catalysts with high CH4 oxidation activity experienced rapid transitions between metallic- and oxidized-Pd states when switching between rich and lean conditions. This behaviour was exhibited by catalysts with dispersed Pd particles. By contrast, the formation of ion-exchanged Pd2+ and large Pd particles appeared to have a detrimental effect on the oxidation-reduction behaviour and the conversion of CH4. The formation of ion-exchanged Pd2+ and large Pd particles was limited by using a highly siliceous beta zeolite support with a low capacity for cation exchange. The same effect was also found using a small-pore SSZ-13 zeolite due to the lower mobility of Pd species. It was found that the zeolite support material should be carefully selected so that the well-dispersed Pd particles remain, and the formation of ion-exchanged Pd2+ is minimized.

One of the common problems in strawberry (Fragaria × ananassa) micropropagation is the vitrification phenomenon (succulent plantlets, brittle stems, yellow leaves, etc.) leading to the reduction of plantlets quality and low survival rate in the greenhouse. In this study, the effects of silver nanoparticles (AgNPs) on explant disinfection, in vitro growth (shoot multiplication, and root formation), runner formation as well as ethylene accumulation during micropropagation of strawberry were investigated. The results showed that leaf explants treated with 200 mg/L AgNPs solution for 20 min was more effective in explant disinfection and shoot regeneration than using 1 g/L HgCl2. In addition, AgNPs stimulated the growth of shoot and plantlet and as well shortened the duration of root formation (4 days) as compared to those in control without AgNPs during micropropagation. Besides, AgNPs reduced the ethylene gas accumulation in the culture’s vessels of shoots (0.66 ppm) and plants (0.06 ppm) compared to controls (1.77 ppm; 0.15 ppm; respectively). Moreover, AgNPs combination with culture period (5; 10 or 15 days) effect root formation stage and acclimatization in the greenhouse. The plantlets that cultured on MS medium supplemethed with 0.5 mg/L AgNPs during 10 days showed higher survival rate (93.33%) after 15 days as well as runner formation per plant (8.00 runners) after 60 days in greenhouse than those in control. AgNPs improved explant disinfection and in vitro growth. AgNPs improved runner formation in the greenhouse. AgNPs limited ethylene accumulation during micropropagation.

The behavior of rPUf (polyurethane foam derived from bis(2-hydroxyethyl) terephthalate (BHET) recovered from post-consumer poly(ethylene terephthalate)-PET bottles) and cPUf (polyurethane foam based on a commercial polyol) were evaluated by comprehensive characterizations, and their thermal stabilities, flammabilities, and physical properties were compared. Without using a flame retardant, rPUf passed the UL-94HB standard, whereas cPUf burned rapidly to the holding clamp. Various formulations of rPUf and cPUf with established eco-friendly fire retardants (FRs), including triphenyl phosphate, aluminum diethylphosphinate, and aluminum trihydroxide, exhibited notably higher fire resistance. The differences between the experimental and calculated densities showed the effectiveness of the foaming process. A larger difference indicated that the FR improved the foaming process more. The BHET structure contains an aromatic moiety that strongly enhanced the compressive strength and protected the rPUf/FRs from biodegradation, as evidenced by sorption isotherm experiments. For that reason, the rPUf/FRs could be used as building materials, especially under high humidity conditions. These are the advantages of BHET over the commercial polyol for PUf preparation. Chemical recycle of post-consumer PET bottles to produce high performance PUf could be applied on an industrial scale and then it creates the sustainable recycling industry.

Smart homes are an element of developing smart cities. In recent years, countries around the world have spared no effort in promoting smart cities. Smart homes are an interesting technological advancement that can make people’s lives much more convenient. The development of smart homes involves multiple technological aspects, which include big data, mobile networks, cloud computing, Internet of Things, and even artificial intelligence. Digital information is the main component of signal control and flow in a smart home, while information security is another important aspect. In the event of equipment failure, the task of safeguarding the system’s information is of the utmost importance. Since smart homes are automatically controlled, the problem of mobile network security must be taken seriously. To address these issues, this paper focuses on information security, big data, mobile networks, cloud computing, and the Internet of Things. Security efficiency can be enhanced by using a Secure Hash Algorithm 256 (SHA-256), which is an authentication mechanism that, with the help of the user, can authenticate each interaction of a given device with a WebServer by using an encrypted username, password, and token. This framework could be used for an automated burglar alarm system, guest attendance monitoring, and light switches, all of which are easily integrated with any smart city base. In this way, IoT solutions can allow real-time monitoring and connection with central systems for automated burglar alarms. The monitoring framework is developed on the strength of the web application to obtain real-time display, storage, and warning functions for local or remote monitoring control. The monitoring system is stable and reliable when applying SHA-256.

This study conducted a survey at 15 building construction and demolition sites in Hanoi, Vietnam in order to identify waste generation rates (WGR), composition, and current handling practices of construction and demolition waste (CDW). Waste quantification based on CDW layout, image analysis to identify CDW components, and face-to-face interviews with construction and demolition contractors to reveal CDW flows were performed. WGRs of 79.3 kg/m2 and 1,030 kg/m2 were determined in small- and large-scale construction sites, respectively, whilst WGRs at small and large demolition sites were 610 kg/m2 and 318 kg/m2. The composition analysis identified soil, concrete, and brick as the major CDW components, consistent with building structures in Vietnam. The interviews discovered that merely 10% of total CDW flows was from recycled and reused CDW. Reuse and recycling rates were most significant for metal and were lower (in descending order) for brick, concrete, and soil. These findings raise a need for aggressive and integrated strategies to promote more sustainable CDW management in the country, including the development of recycled CDW product standards, policies that facilitate recycling, and more importantly, a sustainable business model for CDW recycling, for which future evaluations of economic feasibility are of great importance.

With the advances in radar technology, there is an increasing interest in radar-based applications for automated surveillance, tracking, and recognition. Radars capture the Doppler-induced frequency shifts, which can be utilized to recognize the small motions by vibrating or rotating parts of the target. This paper introduces a fast and compact deep Gabor neural network for human motion classification using backscattered signals from a continuous-wave Doppler radar. The joint time-frequency representation produced by the S-method is employed to depict the micro-Doppler signature of a walking person. We introduce a new Gabor layer as a generic feature extractor for designing compact neural architectures. Each Gabor layer consists of several steerable Gabor filters that can be trained to extract the salient micro-Doppler features and improve computation efficiency. For human motion classification from a distance, the Deep Gabor Network (DGN) is trained in an end-to-end manner to process the local patches in the time-frequency representation of the radar signal. A Bayesian optimization technique is employed to select the optimal network hyperparameters. The experimental results on a real radar dataset show that the proposed method achieves competitive classification rates compared to several existing approaches while having a significantly smaller model size and shorter prediction time.

Refined optimization of complex curve–linear-shaped radiators, such as traveling-wave Vivaldi antennas, can be achieved by considering simulated near fields to interpret in detail the structural influences of a design. The relationships between the space and time distributions of electromagnetic (EM) energy clusters and the geometric features are revealed with appropriate use of impulse response analysis combined with the multiple signal classification (MUSIC) algorithm. This article reports a deeper approach when applied to the adjustment of the geometric features of a traveling-wave antenna based on an analysis of near-field propagation features.

Functional polycarbonate polyols have been synthesized by CO2/propylene oxide (PO) copolymerizations using various Zn(II)-Co(III) double metal cyanide (DMC) catalysts bearing α-, β-, γ-, and δ-dicarbonyl complexing agents (CAs) including dicarboxylic acids, diesters, ketoester, and diketones. The resultant heterogeneous catalysts are intensively characterized by infrared, absorption and X-ray photoelectron spectroscopies, X-ray powder diffraction, and elemental analysis. The produced polycarbonate polyols are characterized using infrared and nuclear magnetic resonance spectroscopies, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis measurements. The catalysts bearing β-, γ-, and δ-dicarbonyl CAs exhibit high activity towards CO2/PO copolymerization and produce polycarbonate polyols with high carbonate content, wide range of molecular weight and narrow polydispersity. The functionality of the resultant polycarbonate polyols varies depending on the type of CAs and the functionality of initiators.

Organic complexing agent (CA) plays a crucial role in generating active sites of double metal cyanide (DMC) catalyst in the ring-opening polymerization (ROP) of epoxides. Considering dicarbonyl compounds are versatile and present a great variety of coordination modes besides the usual bidentate behavior of monoanions, the usefulness of the dicarbonyl compounds as CAs for Zn(II)-Co(III) DMC catalysts is investigated. The structural properties of the catalysts were defined by X-ray powder diffraction patterns, elemental analysis, and thermogravimetric analysis. The interaction of the dicarbonyl ligand on the catalyst surface is evaluated by integrating infrared, UV–vis absorption and X-ray photoelectron spectroscopies. The turnover frequencies (calculated by mol-PO per mol-Zn per minute) of the DMC catalysts bearing β-, γ-, and δ-diesters are significantly higher than those of conventional catalysts specifically bearing tert-butyl alcohol as a CA. The resultant polyols exhibit very low levels of unsaturation and narrow polydispersity indexes. The molecular weight and functionality of the resultant polyols can be tuned by modifying the polymerization parameters. Systematic studies on the effect of the new CAs on the catalytic behavior offer great potential for the synthesis of high quality polyols.

Point-defect engineering is an effective way to control the mobility and transparent-conducting performance of sputtered fluorine-doped ZnO (FZO) thin films. In this study, doping with fluorine (F) is accomplished through a simple one-step deposition process and is demonstrated to enhance the crystal quality, eliminate the point defects, and boost the mobility as well as the performance of the films. Furthermore, the films’ characteristics are observed to be strongly dependent on F content. At the optimum F content of 1%, the FZO films exhibited the best crystal quality and the lowest concentration of Zn interstitial and O vacancy defects due to F passivation. Moreover, a mobility as high as 45.3 cm2/V and the greatest figure-of-merit performance are achieved for cutting-edge transparent electrode applications. However, a further increase of F content brought about an increased concentration of defects relating to Zn vacancies, especially F interstitials, which yielded the low mobility and poor performance due to the degraded structure.

Perovskite oxides have emerged as promising alternatives for the supported Platinum group metal catalysts for total oxidation of propane and other volatile organic compounds (VOC). Here, we report a surface modification method to improve propane oxidation activity of La0.8Sr0.2CoO3 monolithic catalysts using diluted oxalic acid etching. The oxalic acid treatment decreases the light-off temperatures of propane oxidation by 30–40 °C. Experimental and DFT investigations reveal that the treatment selectively etches Sr cations and slightly reduces LSCO surface, leading to an increased population of low-valence Co2+ Lewis acid sites, which promotes activation of lattice oxygen and adsorbed oxygen species and facilitates propane adsorption and dissociation. Our work offers a rapid strategy to activate perovskite monolithic catalysts and will inspire the research on surface modification of perovskite catalyst.

The discrete-element method (DEM) has gained popularity for developing a qualitative understanding of soil behaviour under a critical state soil mechanics (CSSM) framework. Most studies with a three-dimensional assembly of particles have used spheres as representative granular material to reduce computational demands. However, most granular materials – for example, sands – are not rounded, but possess features of angularity. Therefore, ellipsoid and cluster particles with different degrees of eccentricity were used in this study to evaluate the effect of the particle shape on the drained and undrained triaxial loading behaviour after isotropic and K0 consolidation. The particle numerical properties and grain size distributions were kept the same for all specimens, irrespective of particle shape. The critical state data points for spheres and ellipsoids plotted on almost the same critical state line (CSL) in e–log(p′) space, whereas the CSLs of clusters plotted above them. Additionally, M lines shifted downward with increasing sphericity. It was also found that the stress ratio at the triggering of static liquefaction (ηIS = q/p′) in ηIS–ψ space was affected by particle shape and consolidation path. The dilatancy (d = dεvp/dεqp) was also affected by particle shape. It was found that dilatancy parameters for the SANISAND constitutive model are affected by particle shape, which may contribute to an improved understanding of particle shape in constitutive modelling.

Recently, Zou et al. (2020a) published a theoretical analysis on the radial flow of a Bingham fluid, where they argued that the classical analysis by Dai and Bird (1981) violates the mass conservation. The present discussion aims to clarify this conflict between those two studies. It is noted that Zou et al. (2020a) presumed the gap-wise mass flux is negligible in the mass conservation equation, while Dai and Bird (1981) did not require so in their model, and this is found to be the origin of the conflict. In fact, Dai and Bird (1981)’s model is shown to not violate the mass conservation. Therefore, those two models should be viewed as separate models derived from different perspectives. Details of the major difference between the two models are discussed.

The Pd-catalysed asymmetric allylic alkylation (Pd-AAA) of prochiral enamide anions derived from 5H-oxathiazole 2,2-dioxides has been developed. Various 4,5-disubstituted and 4-substituted cyclic sulfamidate imines have participated in the transformation with a range of allyl carbonates—as well as 2-vinyl oxirane, 2-vinyl-N-tosylaziridine, and 2-vinyl-1,1-cyclopropane dicarboxylate—to furnish the desired C-allylated products in moderate to high yields, with high regioselectivites and generally high enantioselectivities. Conversion between N- and C-allyl products was observed, with the N-allylated products converting to the C-allylated products over time. The resulting high-value allylated heterocyclic products all bear a tetrasubstituted stereogenic centre and can be reduced to an allylated chiral sulfamidate or an amino alcohol., The Pd-catalysed asymmetric allylic alkylation (Pd-AAA) of prochiral enamide anions derived from 5H-oxathiazole 2,2-dioxides has been developed.

Development of the technological and industrial capabilities to obtain hexagonal gibbsite nanoplatelets with a regularly well-defined configuration is an ongoing consideration that has not yet covered a required level of feasible architecture. Here we present a convenient method to synthesize the colloidal gibbsite particles based on a simple hydrothermal process from aluminum alkoxides in weak acid media. These colloids are near-regularly shaped and fairly monodisperse hexagons with an average diameter of 185 nm and a thickness of ~5.3 nm. The aqueous dispersion of gibbsite platelets can be shear-aligned to form highly ordered, continuous films on a substrate by an industrially adaptable method for producing large-area membranes. Overall, the modified synthesis method exhibits an excellent potential for scalable-up production with high quality in various practical applications. The aligned films also have outstanding properties due to the self-assemblies and interfacial physical interactions between adjacent gibbsite platelets and the possibility of industrial fabrication from those layered structural materials. Moreover, we prepare this shear-aligned membrane by the in-plane shearing method to introduce the great promise of disk-like-derived gibbsite as new gas-barrier material or surface-protective materials.

This study evaluated the performance of a low-cost natural laterite from Thach That (NLTT), Vietnam, for its capacity to remove arsenic (As) in a household filter with contaminated groundwater. The NLTT was initially tested in a laboratory column trial lasting 800 h. The breakthrough curves were found to fit the Thomas model very satisfactorily with adsorption capacities of 0.06 and 0.20 mg/g at a flow velocity of 0.85 m/h for the influent As(V) concentrations of 0.1 and 0.5 mg/L, respectively. In household filters at four sites, the median As concentration in groundwaters (0.04–0.19 mg/L) dropped to 0.026–0.054 mg/L after traditional sand filtration. However, following subsequent NLTT filtration through columns (14 cm inner diameter, 65 cm height) at 0.65 m/h flow velocity, it fell to below the Vietnam and WHO drinking water standard (0.01 mg/L) during seven months of continuous operation. Portland cement and lime were tested as binding agents for the exhausted NLTT waste in a solidification/stabilization process at different ratios. The best ratio of exhausted NLTT: Portland cement: lime for restraining mobility of As from this waste was 3:1:0.5. The concrete brick products exhibited a suitable compressive strength for using it as building materials in construction work.

Antibiotic residues and antimicrobial resistance in surface water are issues of global concern, especially in developing countries. In this study, the occurrence of seven antibiotics and one antiparasitic agent was determined in surface water samples collected from four rivers running through Hanoi urban area in the Red River Delta, northern Vietnam. The pharmaceuticals in water samples were analyzed by solid-phase extraction combined with liquid chromatography-tandem mass spectrometry method. The concentrations of pharmaceuticals in our samples ranged from 3050 to 16,700 (median 7800) ng/L, which were generally higher than levels found in river water from many other locations in the world. Amoxicillin, oxfendazole, and lincomycin were the most dominant and frequently detected compounds (detection rate 100%), which together accounted for 76 ± 14% of total concentrations. Sulfacetamide and sulfamethoxazole were detected at moderate concentrations in more than two-thirds of the analyzed samples. The remaining antibiotics (i.e., azithromycin, ciprofloxacin, and ofloxacin) were found at lower detection frequency and concentrations. Antibiotic concentrations in the water samples were not significantly different between the investigated rivers. Meanwhile, levels of pharmaceuticals in the samples collected in February 2020 were higher than those found in the remaining samples, largely due to the sharp decrease in sulfamethoxazole and azithromycin concentrations of the samples collected in March and April. Considerable ecological risks of antibiotics in surface water were estimated for some compounds such as amoxicillin, ciprofloxacin, and ofloxacin.

A colorimetric chemosensor for hydrogen peroxide (H2O2) and biosensor for cholesterol is developed in this work following a ‘label-free and reagentless’ concept. In this strategy, silver nanoparticles (AgNPs) are used as a bifunctional probe, namely, a chemical capture probe for H2O2 recognition and a signal probe for displaying detection results. The working principle of these colorimetric sensors is based on the redox reaction between AgNPs and H2O2. This reaction converts AgNPs into Ag+ ions, which can induce a visible color change from yellow to pinkish or colorless depending on the amount of H2O2. Therefore, H2O2 concentration can be measured. The developed colorimetric H2O2 chemosensor exhibits a highly selective and sensitive property towards H2O2 with a limit of detection (LOD) of 3.5 μM. Subsequently, a colorimetric biosensor is developed for cholesterol detection by combining AgNPs and cholesterol oxidase (ChOx) enzyme. Here, ChOx oxidizes cholesterol into cholest-4-en-3-one and H2O2. Then, the detected as-generated H2O2 concentration reflects the cholesterol level in the sample. This cholesterol biosensor exhibits high selectivity and sensitivity for cholesterol detection with a LOD of 40 μM. The developed sensor is successfully applied to the detection of cholesterol levels in serum samples. Our results show that the AgNP–based colorimetric method is cost-effective, sensitive and selective. It has potential applications in H2O2 and cholesterol detection and in clinical and medical diagnoses.

In this study, the gross calorific value (GCV) of coal was accurately and rapidly determined using eight artificial intelligence models based on big data of 2583 observations of coal samples in the Mong Duong underground coal mine (Vietnam). Accordingly, the volatile matter, moisture, and ash were considered as the key variables (inputs) for determining GCV. Seven artificial neural network (ANN) models were developed to estimate GCV as the first stage. Subsequently, the best ANN model (with the highest performance) was selected as the initial ANN model for the optimization process, i.e., ANN 3-12-9-1 model. The particle swarm optimization (PSO) algorithm was applied to perform a global search for the optimal weights/biases of the selected ANN model. This novel procedure is denoted as PSO-ANN. A variety of performance metrics was used to assess the quality of the training process, as well as the models’ performance in the testing dataset. The results revealed that the models developed in this study could determine GCV rapidly and accurately. Of those, the PSO-ANN model provided the highest accuracy in estimating GCV of coal with a root-mean-squared error of 182.476, the correlation coefficient of 0.964, the variance accounted for of 96.411, and mean absolute percentage error of 0.016. Besides, the analyzed and compared results also indicated that the PSO algorithm played a significant role in improving the accuracy of the ANN model. It was introduced as an alternative solution to determine the GCV of coal in practical engineering rapidly.

In this study, sol–gel combining with hydrothermal methods were successfully used to synthesize N and S co-doped TiO2 nanotubes (N@S-TiO2 NTT) for efficient photocatalytic degradation of volatile organic compounds (VOCs). The obtained characterization results indicated that the synthesized N@S co-doped TiO2 existed as nanotubes. Specific surface areas of these synthesized nanotubes was greatly that of these nanoparticles. The largest surface area recorded at N@S-TiO2 nanotubes was 105.3 m3/g. FTIR spectrum results showed that the presence of N–H and S–O bond, which confirmed that nitrogen and sulfur were successfully doped into TiO2 lattice. We also investigated that N@S dopants significantly improved the photocatalytic activity of TiO2 nanotubes for efficient degradation of gaseous VOCs. Therefore, photocatalytic activity for VOCs degradation by the N@S-TiO2 nanotubes was greater than that by the undoped TiO2 nanotube. Optimized humidity for degradation of VOCs was medium condition (55–70%). Under dry conditions, lack of water for hydroxyl radical production led to decrease in photocatalytic activity. Under humidity conditions, the excess water molecules competed with VOCs for adsorbing on material surface leading to decrease in photocatalytic degradation efficiency. Under the optimized humidity, the highest photocatalytic efficiency of the synthesized N@S-TiO2 nanotubes for degradation of gaseous VOCs for 3 h was approximately 94%. The VOCs degradation capacity by the synthesized N@S-TiO2 nanotubes was approximately 90 (ppm/g h).

Herein, we used polypyrrole (PPy), a conducting polymer, to decorate on CuWO4 to boost its photocatalytic activity. Then, the synthesized PPy decorated on CuWO4 (PPy/CuWO4) materials were applied to photocatalytically split water to produce hydrogen. The study investigated that the used PPy effectively served as a spring-board (sensitizer) to improve charge (e− and h+) separation of the CuWO4 photocatalyst. The used PPy also effectively increased Fermi level of these separated e− of the CuWO4. Thus, the PPy/CuWO4 generated large available and strong charges, which effectively split water to generate hydrogen. The optimal PPy decorating content for the highest water splitting efficiency is shown to be 4 wt%. Above the optimal decorating content, these excess PPy covered more CuWO4 surface preventing incident irradiation reaching to the material leading to decrease in photocatalytic efficiency. The H2 generation from photocatalytic water splitting by the 4PPy/CuWO4 were 365 (μmol. g−1cat. h−1). It is further observed that the used PPy, which completely covered the CuWO4 particles, effectively assisted charge transfer for their rapid travel to the polymer surface. Thus, the used PPy successfully prevented contact between charges and CuWO4 to protect the material from self-photocorrosion through water splitting process.

In this work, magnetic graphene oxide nanocomposites were synthesized by co-precipitation method and used as an adsorbent for removal of arsenic (V) ions from water. The structure and morphology of magnetic graphene oxide nanocomposites were studied by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area, and vibrating sample magnetometry. Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy results of magnetic graphene oxide presented that the Fe3O4 nanoparticles in the size range of 10–25 nm were decorated on graphene oxide nanosheets. The adsorption properties of magnetic graphene oxide nanocomposites for arsenic (V) from water were investigated to study the effects of magnetic graphene oxide mass ratio, contact time, pH, and initial concentration. The suitable magnetic graphene oxide mass ratio of nanocomposites for arsenic (V) adsorption was determined to be 4:1 (FG2). The adsorption process on FG2 followed a pseudo-second-order kinetic and well fitted in to Langmuir isotherm model with the maximum adsorption capacity of 69.44 mg/g at pH 3. Accordingly, FG2 could be used as an effective adsorbent for removal of arsenic (V) from water.

The purposes of the study presented in this article were twofold. One was to respond to the question: what makes a quality curriculum? within the framework of the fourth United Nations Sustainable Development Goal (SDG 4). The other was to develop and pilot an appropriate instrument to evaluate the quality of curricula in a sample of private schools in Vietnam. While public schools are still preparing for implementation of Vietnam’s New General Educational Curriculum, small adjustments are already being made to the curriculum in some private and international schools in Vietnam, which have been issued a curriculum customisation licence. Therefore, the pilot schools which participated in this study can serve as case studies for the upcoming major policy improvement in Vietnam’s public schools, thus providing guidance for Vietnamese policymakers, school principals and teachers. While there is no “one-size-fits-all” curriculum assessment formula, since each country exhibits distinctive features in its teaching and learning programme, the indicators developed by the authors for their study can be adjusted to suit the needs of other countries.