The burnishing process is an efficient finishing operation which is widely used to enhance the surface properties of the machined components. The published works mainly focused on the parameters ...optimization of the burnishing process in which objective functions are relative to burnished surface qualities. Because of natural resource exhaustion and the rising energy prices, the reduction in energy consumption is an urgent demand in the manufacturing industry. This paper presented an efficient optimization to simultaneously decrease energy consumption as well as the mean roughness depth and improve the Brinell hardness for the burnished surface of H13 steel. The burnishing speed, feed rate, depth of penetration, and the number of rollers were the input parameters. The burnishing processes were carried out on a CNC milling machine. The mathematical relations between inputs and outputs were developed using the radius basis function models. The multi-objective particle swarm optimization and the technique for order of preference by similarity to ideal solution were used to generate the Pareto fronts and to determine the best solution. The results show that energy consumption and surface roughness are reduced by 39.50% and 7.83%, respectively. The Brinell hardness is improved by 29.61% compared to the initial values. The radial basis function models can be effectively used to render the approximations and to predict the response’s values. The proposed method can be considered as a sufficient approach for modeling and optimizing the burnishing process.
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•Optimizing processing conditions for the roller burnishing of H13 steel. .•Considering energy consumed, mean roughness depth, and Brinell hardness.•Development of the correlations using radius basic function (RBF) models.•Evaluating alternative solutions using the multi-performance index (MPI).•Determination of optimal factors using RBF-MOPSO-TOPSIS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report here a simple approach for synthesis of carbon coated magnetite (C@MFe
2
O
4
, M=Co, Ni, Fe) with shell@core nanostructured composites that we used as magnetic-nanosorbents for direct ...yellow (DYG) and moderacid red (RS) as pollutant textile dyes removal via an adsorption process. The synthesized C@MFe
2
O
4
was characterized by TEM, SEM, EDX, XRD, FT-IR and VSM techniques. TEM results indicated that C@MFe
2
O
4
nanocomposites have 20–30 nm of MFe
2
O
4
nanoparticle core and 2–3 nm in thickness of the amorphous carbon shell. The synthesized C@MFe
2
O
4
nanocomposites have the zero point charge (pH
ZPC
) at 5.5, which suggests that DYG and RS, anionic dyes can be adsorbed onto the C@MFe
2
O
4
nanosorbents in the acidic medium. Adsorption of DYG and RS onto magnetic nanosorbents was optimized and adsorption thermodynamic parameters were evaluated, clearly indicating that the adsorption of RS onto synthesized magnetic-nanosorbents was facile more than that DYG. The adsorption isotherm data showed that the adsorption processes of DYG and RS onto Fe
3
O
4
or C@MFe
2
O
4
nanosorbents are more suitable for the Langmuir model than Freundlich model. The maximum adsorption capacity (q
max
) of DYG dye onto Fe
3
O
4
, C@Fe
3
O
4
and C@CoFe
2
O
4
adsorbents was 14.641, 36.232 and 7.85 mg g
−1
, respectively; meanwhile, these values were 41.152, 61.728 and 39.683 mg g
−1
for RS dye. These obtained data indicate that the developed Fe
3
O
4
, C@Fe
3
O
4
and C@CoFe
2
O
4
nanoparticles can be used as recoverable and recyclable adsorbents for not only organic pigments adsorption but also for heavy metal ion removal or protein extraction as well.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The series of 2-amino-7-propargyloxy-4H-chromene-3-carbonitriles 5a-t were synthesized from corresponding 2-amino-7-phydroxy-4H-chromene-3-carbonitriles 4a-t and propargyl bromide. Two procedures ...were used in these syntheses: K2CO3/acetone and NaH/DMF procedures with yields of 65–89% and 80–96%, respectively. 1H-1,2,3-Triazole-tethered 4H-chromene−d-glucose conjugates 7a-t were synthesized using click chemistry of propargyl ethers 5a-t and tetra-O-acetyl-β-d-glucopyranosyl azide. Cu@MOF-5 was the optimal catalyst for this chemistry. The yields of 1H-1,2,3-triazoles were 80–97.8%. All triazoles 7a-t were evaluated in vitro for anti-microorganism activities. Among tested compounds with MIC values of 1.56–6.25 μM, there were four compounds against B. subtilis, four compounds against S. aureus, and four compounds against S. epidermidis; five compounds against E. coli, four compounds against K. pneumoniae, five compounds against P. aeruginosa, and six compounds against S. typhimurium. Compounds 7c,7d,7f,7h, and 7r had MIC values of 1.56–6.25 μM for three clinical MRSA isolates. Some compounds had inhibitory activities against four fungi, including A. niger, A. flavus, C. albicans, and S. cerevisiae, with MIC values of 1.56–6.25 μM. Some 1H-1,2,3-triazoles had comparatively low toxicity against RAW 264.7 cells.
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•Novel 1H-1,2,3-triazole-tethered 4H-chromene−d-glucose conjugates by click chemistry.•Several triazoles were active for three strains of Gram-(+), four strains of Gram-(−) bacteria (MICs = 1.56–6.25 μM).•Some triazoles had activity against four strains of fungi with MICs of 1.56–6.25 μM.•7c,7d,7f,7h, 7r exerted anti-MRSA activities against all strains with MIC of 1.56–6.25 μM.•1H-1,2,3-Triazoles 7c,7d,7f,7h, 7r had comparatively low cytotoxicity against RAW 264.7 cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Novel twenty-four 1H-1,2,3-triazole-tethered 4H-pyrano2,3-dpyrimidine−d-glucose conjugates.•8g, 8t, 8u, 8v, 8x, and 8y: inhibitory activity IC50 = 1.56–9.52 μM against ...MtbPtpB.•Ser57, Arg59, Hid94, and Phe98 residues of 2OZ5 created the specific binding pocket.
Some heterocycles, namely 2-amino-4H-pyran-3-carbonitriles, were synthesized in a three-component reaction from substituted benzaldehydes, malononitrile, and ethyl acetoacetate. These heterocycles have been converted subsequently into 4H-pyrano2,3-dpyrimidine ring by ring-closing reaction with acetic anhydride in the presence of the concentrated sulfuric acid as catalyst. The successive alkylation reaction of lactam NH bond on pyrimidine-4-one ring was carried out using propargylic bromide in dry acetone in the presence of anhydrous potassium carbonate. The click chemistry of 3-propargyl-4H-pyrano2,3-dpyrimidine compounds has been accomplished by reaction with tetra-O-acetyl-α-d-glucopyranosyl azide using the metal-organic framework Cu@MOF-5 as a catalyst in absolute ethanol. All the synthesized 1H-1,2,3-triazoles 8a–y were screened for their in vitro Mycobacterium tuberculosis protein tyrosine phosphatase B (MtbPtpB) inhibition. Kinetic studies of the most active compounds 8v, 8x, and 8y showed their competitive inhibition toward the MtbPtpB enzyme. The detailed structure-activity relationship (SAR) in vitro and in silico studies suggested that the interaction of Arg63 amino acids with anion type of para-hydroxyl group via a salt bridge of iminium cation was essential for strong inhibitory activity against MtbPtpB.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sudden cardiac arrest (SCA) consisting of ventricular fibrillation and ventricular tachycardia considered as shockable rhythms is a life-threatening heart disease, which is treated efficiently by the ...automated external defibrillator (AED). This work proposes a novel design of the SAA, which includes a k-nearest neighbors model and a subset of 8 features extracted from the ECG segments, for the SCA diagnosis on the electrocardiogram (ECG) signal. These features are addressed as the most productive subset among 31 input features based on the evaluation of the feature correlation. The recursive feature elimination algorithm combined with the Boosting model and wise-patient fivefold cross-validation method is adopted for the calculation of the average feature importance, which shows the degree of feature correlation, to construct various input feature subsets. Moreover, component feature combinations known as the representatives of the input feature subsets with an enormous level of correlation and independence are transformed from the input subsets by the principal component analysis method. The wise-patient fivefold cross-validation procedure is used for the evaluation of these component feature combinations on the validation set. The proposed SAA is certainly efficient for SCA detection with a small number of the extracted feature and relatively high diagnosis performance such as accuracy of 99.52%, sensitivity of 97.69%, and specificity of 99.91%.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this study, a parametric analysis was conducted for the design of a suggested dual flapping hydrofoil turbine. A Navier–Stokes‐based computational fluid dynamics code was utilized for the analysis ...while varying the pitch angle, reduced frequency, separation distance, and phase difference. The smallest pitch angle of 60° and the reduced frequency of 0.1 among the given ranges of the parameters were fixed for the first parametric analysis. After an assessment, the 90° front‐lead with the longest distance of 6c and the 90° rear‐lead with the shortest distance of 2c were chosen for further parametric analysis based on a suggested performance indicator and a margin for improvement. It was derived from a subsequent parametric analysis that a 70° pitch angle, 0.12 reduced frequency, and a 4c distance for the 90° front‐lead was the final optimum with 59.48% efficiency and 55.44% fluctuation according to the performance indicator as well as the system length and power balance of dual hydrofoils.
We suggested a dual flapping hydrofoil turbine system that mimics the leg structure and swimming scheme of ancient marine dinosaurs or turtles. To design it, a numerical parametric study was carried out to determine the separation distance and phase difference between the front and rear hydrofoils. Through this study, the case of 70° pitch angle of (4c, front‐lead) was chosen as optimal by obtaining 0.595 efficiency showing approximately 93% of the Newman limit of 0.640 for tandem turbines.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Using a simple, low cost, and excellent efficient approach, carbon dots (CDs) were fabricated via a one-pot hydrothermal process of coffee waste. Amazingly, the combination of 2% CDs with ZnBi2O4 to ...form a new and excellent heterogeneous photocatalyst enabled the complete decomposition of 2, 4-dichlorophenoxyacetic acid (2, 4-D) into CO2 and H2O. The findings of this study provide a new perspective on the utilization of agricultural waste for creating products of scientific and practical significance. More than 91% of 2, 4-D (initial concentration of 30 mg/L) was completely decomposed and dechlorinated using 1.0 g/L of CDs (2%)-ZnBi2O4 at pH 4.0 after 120 min of exposure to visible light (with k = 0.0178 min−1), and more than 86% of the decomposed 2, 4-D was mineralized into CO2 and H2O. There was no sign of catalyst deactivation after four cycles of reuse, demonstrating the durability and efficiency of CDs (2%)-ZnBi2O4. The significant improvement in the photocatalytic efficiency of CDs (2%)-ZnBi2O4 compared with that of bare CDs or ZnBi2O4 is due to the formation of defects at the interfaces of the heterojunction; therefore, the movement of photogenerated electrons at the interface between the two components is rapid. The mineralization of 2, 4-D by CDs (2%)-ZnBi2O4 upon exposure to visible light is induced mainly by the photogenerated holes, followed by O2•−, and finally OH• radicals.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
In this research, a camber changing mechanism feasible for use in a flapping hydrofoil tidal stream turbine is suggested to generate high lift force and subsequently a large flapping angle as a ...dynamic response. The hydrodynamic characteristics of rigid and variable-camber hydrofoils, which mainly affect the response, were numerically obtained using XFOIL. The flapping responses of the hydrofoils were estimated by a validated nonlinear dynamic model with the hydrodynamic characteristics. The estimated responses of a variable-camber hydrofoil were compared with the measured responses of the rigid hydrofoil from a previous study as well as the estimated responses of a rigid hydrofoil. It was shown from these comparisons that the variable-camber hydrofoil produced a much higher flapping angle amplitude with the same pitch angle relative to that of the rigid wing due to the cambered shape of the former. Moreover, the variable-camber hydrofoil could generate considerable flapping responses compared to experimental data, even when a relative small input pitch angle was applied in the estimation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A superior heterojunction of HC-ZnBi-LDO was synthesized in two steps, namely hydrothermal carbonization, followed by co-precipitation. The 2% HC-ZnBi-LDO heterojunction photocatalysts could degrade ...over 90.8% of 30 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) using 1.0 g/L of the catalyst after 135 min of visible light exposure at pH 4. The activity of 2% HC-ZnO-LDO was remarkably stable. Approximately 86.4-90.8% of 30 mg/L 2,4-D was degraded, and more than 79-86.4% of TOC was mineralized by 2% HC-ZnBi-LDO at pH 4 after 135 min of visible light exposure during four consecutive cycles. The rapid separation and migration of charge carriers at the interfaces between HC and ZnBi-LDO were achieved within 2% HC-ZnBi-LDO. Moreover, the electron acceptor characteristic of HC in 2% HC-ZnBi-LDO caused the recombination of charge carriers to decrease significantly, thus generating more reactive radicals, such as hydroxyl radicals (OH
) and superoxide radicals (O
). These results demonstrate that the novel 2% HC-ZnBi-LDO is a superior photocatalyst for the remediation of hazardous organic pollutants.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Anthrax is a priority zoonosis for control in Vietnam. The geographic distribution of anthrax remains to be defined, challenging our ability to target areas for control. We analyzed human anthrax ...cases in Vietnam to obtain anthrax incidence at the national and provincial level. Nationally, the trendline for cases remained at ≈61 cases/year throughout the 26 years of available data, indicating control efforts are not effectively reducing disease burden over time. Most anthrax cases occurred in the Northern Midlands and Mountainous regions, and the provinces of Lai Chau, Dien Bien, Lao Cai, Ha Giang, Cao Bang, and Son La experienced some of the highest incidence rates. Based on spatial Bayes smoothed maps, every region of Vietnam experienced human anthrax cases during the study period. Clarifying the distribution of anthrax in Vietnam will enable us to better identify risk areas for improved surveillance, rapid clinical care, and livestock vaccination campaigns.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
