Display omitted
In materials technology, composites are considered as one of the potential materials due to their stable structure, ability to contain functional groups that are essential for ...adsorption, porosity and large specific surface area, and processing process. Metal-organic framework materials based on carboxymethyl cellulose (CMC) substrates were synthesized through a solvothermal method to recover the antibiotic ciprofloxacin in an aqueous medium. Several experimental parameters that affect the adsorption process were investigated, including adsorption time, solution pH, ionic strength, and initial concentration. The langmuir isotherm and pseudo-second-order are in close agreement with the ciprofloxacin adsorption assay data. The CoFe-MOF aerogel material at the ratio of 1 CMC has a relatively high CIP adsorption capacity with an adsorption capacity of 226.8 mg/g at pH 8, an initial CIP concentration of 80 ppm for 90 min. The Box-Behnken design was used to optimize the adsorption process through 15 runs of experiments based on the response surface method (RSM). The analysis of variance (ANOVA) showed that the correlation between the test and the prediction followed the quadratic polynomial model with the regression parameter R2 = 0.9984. The optimal conditions for removal of 64.85% CIP were predicted to be 0.013 g/L CoFe-MOF aerogel, a CIP concentration of 92.42 mg/L, and a pH 7.26 within 90 min. In addition, the electrostatic interaction between the adsorbent and the adsorbent surface is significantly affected by the competition of Na ions in the salt and the solution pH value. In summary, CoFe-MOF aerogel is considered a suitable material that can have significant effects on wastewater treatment and a potential candidate for extended advanced research.
In this work, Pt-SiO2/graphene nanocomposites have been synthesized under solvothermal conditions and investigated as electrocatalysts for methanol oxidation. Structure and morphology of these ...catalysts are characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and nitrogen adsorption/desorption studies. The Pt and SiO2 contents of these nanocomposites are determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Their electrocatalytic properties are investigated by cyclic voltammetry, chronoamperometry, chronopotentiometry and electrochemical impendence spectroscopy. The as-prepared nanocomposites show the improved catalytic performance, better stability and good antiposoining ability compared with Pt supported on graphene catalyst. Particularly, the catalyst containing 9.24% of SiO2 exhibits the best electrocatalytic performance for methanol oxidation with mass activity of 1047mAmg−1.
Display omitted
•Pt/rGO catalysts were successfully synthesized using either NaBH4 or ethylene glycol.•Synthesis using NaBH4 could improve electrocatalytic towards methanol oxidation of Pt/rGO ...catalyst.•40%Pt/rGO synthesized using NaBH4 showed the best electrocatalytic performance.
The synthesis processes of Platinum (Pt) on reduced graphene oxide (rGO) catalysts from graphene oxide (GO) using two reducing agents including sodium borohydride and ethylene glycol is reported. Structure and morphology of Pt/rGO catalysts are characterized by X-ray powder diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrocatalytic methanol oxidation properties of these catalysts are evaluated by cyclic voltammetry and chronoamperometry. The results show that catalyst synthesized using sodium borohydride has a higher metallic Pt content and an improved catalytic performance in comparison to catalyst synthesized using ethylene glycol. Moreover, effect of Pt loading amount on electrocatalytic methanol oxidation performance of catalysts synthesized using sodium borohydride is systematically investigated. The optimal Pt loading amount on graphene is determined to be 40%.
A brief gonadotropin-releasing hormone analogues (GnRHa) stimulation test which solely focused on LH 30-minute post-stimulation was considered to identify girls with central precocious puberty (CPP). ...However, it was tested using traditional statistical methods. With advanced computer science, we aimed to develop a machine learning-based diagnostic model that processed baseline CPP-related variables and a brief GnRHa stimulation test for CPP diagnosis.
We recruited girls suspected of precocious puberty and underwent a GnRHa stimulation test at Children Hospital 2, Vietnam, and Cathay General Hospital, Taiwan. Clinical data, bone age measurement, and 30-min post-stimulation blood test were used to build up the predictive model. The candidate model was developed by different machine learning algorithms that were mainly evaluated by sensitivity, specificity, the area under the receiver operator characteristic curve (AUC), and F1-score in internal and external validation data to classify girls as CPP and non-CPP at different time-points (0-min, 30-min, 60-min, and 120-min post-stimulation).
Among the 614 girls diagnosed with PP, 524 (85.3%) had CPP. The random forest algorithm yielded the highest value of F1-score (0.976), specificity (0.893), positive predicted value (0.987), and relatively high value of AUC (0.972) that contributed to high probability to identify CPP. The performance metrics of the 30-min post-stimulation diagnostic model including sensitivity and specificity surpassed those of the 0-minute model (0-min) and were equivalent to those of the model obtained 60-min and 120-min post-stimulation. Hence, our machine learning-based model helps shorten the stimulation test to 30 minutes after GnRHa injection, in general, it requires 120 minutes for a completed GnRHa stimulation test.
We developed a diagnostic model based on clinical features and a single sample 30-minute post-stimulation to identify CPP in girls that can reduce distress for children caused by multiple blood samplings.
Osteoporosis contributes significantly to health and economic burdens worldwide. However, the development of osteoporosis-related prediction tools has been limited for lower-middle-income countries, ...especially Vietnam. This study aims to develop prediction models for the Vietnamese population as well as evaluate the existing tools to forecast the risk of osteoporosis and evaluate the contribution of covariates that previous studies have determined to be risk factors for osteoporosis. The prediction models were developed to predict the risk of osteoporosis using machine learning algorithms. The performance of the included prediction models was evaluated based on two scenarios; in the first one, the original test parameters were directly modeled, and in the second the original test parameters were transformed into binary covariates. The area under the receiver operating characteristic curve, the Brier score, precision, recall and F1-score were calculated to evaluate the models' performance in both scenarios. The contribution of the covariates was estimated using the Permutation Feature Importance estimation. Four models, namely, Logistic Regression, Support Vector Machine, Random Forest and Neural Network, were developed through two scenarios. During the validation phase, these four models performed competitively against the reference models, with the areas under the curve above 0.81. Age, height and weight contributed the most to the risk of osteoporosis, while the correlation of the other covariates with the outcome was minor. Machine learning algorithms have a proven advantage in predicting the risk of osteoporosis among Vietnamese women over 50 years old. Additional research is required to more deeply evaluate the performance of the models on other high-risk populations.
A simple and green chemistry approach for the preparation of reduced graphene oxide nanosheets was successfully demonstrated through the reduction of graphene oxide (GO) using caffeine as the ...reductant. Without using toxic and harmful chemicals, this method is environmentally friendly and suitable for the large-scale production of graphene. The samples of GO, before and after reduction with caffeine have been characterized by X-ray diffraction, Raman, Fourier transform infrared, X-ray photoelectron spectroscopy, thermogravimetric analysis and transmission electron microscopy.
Two new lignans (7S,7′R,8S,8′R)-3,3′-dimethoxy-7,7′-epoxylignan-4,4′,9-triol 4-O-β-D-glucopyranoside (1) and 9-O-formylaviculin (2) together with other thirteen known secondary metabolites were ...isolated from the leaves of Antidesma hainanensis. Their chemical structures were determined using NMR, electrospray ionization (ESI)-MS, circular dichroism (CD) spectroscopic methods, and as well as by comparison with those reported in the literature. Neuro-inflammatory activity of isolated compounds was evaluated by their inhibition on nitric oxide (NO) production in activated BV2 microglial cells. At concentration of 40 µM, compounds 1–3, 5, 7, 8, 9, 14, and 15 exhibited inhibitory effects over 50%, suggesting that they could be potential candidate drugs for the cure of neuro-inflammation. In addition, compounds 1, 8, 14, and 15 significantly inhibited 16.23, 27.76, 21.23, and 29.44% NO production at diluted concentration as low as 2.5 µM.
Kombucha is sweetened black tea that is fermented by a symbiosis of bacteria and yeast embedded within a cellulose membrane. It is considered a health drink in many countries because it is a rich ...source of vitamins and may have other health benefits. It has previously been reported that adding lactic acid bacteria (
Lactobacillus
) strains to kombucha can enhance its biological functions, but in that study only lactic acid bacteria isolated from kefir grains were tested. There are many other natural sources of lactic acid bacteria. In this study, we examined the effects of lactic acid bacteria from various fermented Vietnamese food sources (pickled cabbage, kefir and kombucha) on kombucha’s three main biological functions: glucuronic acid production, antibacterial activity and antioxidant ability. Glucuronic acid production was determined by high-performance liquid chromatography–mass spectrometry, antibacterial activity was assessed by the agar-well diffusion method and antioxidant ability was evaluated by determining the 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity. Four strains of food-borne pathogenic bacteria were used in our antibacterial experiments:
Listeria monocytogenes
ATCC 19111,
Escherichia coli
ATCC 8739,
Salmonella typhimurium
ATCC 14028 and
Bacillus cereus
ATCC 11778. Our findings showed that lactic acid bacteria strains isolated from kefir are superior to those from other sources for improving glucuronic acid production and enhancing the antibacterial and antioxidant activities of kombucha. This study illustrates the potential of
Lactobacillus casei
and
Lactobacillus plantarum
isolated from kefir as biosupplements for enhancing the bioactivities of kombucha.
The current study reports the preparation and investigation of several Pt-based anode catalysts loaded on reduced graphene oxide (rGO) as electrocatalysts in both acid and alkaline media for ethanol ...electrooxidation. The synthesized catalysts are evaluated by the method of XRD, Raman spectroscopy, XPS and TEM. Electrocatalytic properties of these catalysts for ethanol oxidation were investigated by cyclic voltammetry and chronoamperometry. It was found that the as-prepared nanocatalysts doped by metals and oxide metals showed the improvement of catalytic performance compared to Pt-only supported on graphene catalyst. The results indicated that the presence of Al favoured Pt nanoparticles dispersing on the surface of rGO sheets. Indeed, the PAG catalyst exhibits the highest mass activity for the ethanol oxidation of 1194 mA mg−1Pt in acid medium and 3691 mA mg−1Pt in alkaline medium. In addition, the PAG catalyst also shows good antipoisoning ability for ethanol electrooxidation in both media. This catalyst could be a potential catalyst for direct ethanol fuel cell (DEFC).
•Graphene-supported Pt-based multimetallic catalysts were successfully synthesized.•Electrocatalytic performances of catalysts were examined in acid and alkaline media.•Catalyst containing Pt and Al shows the best electroactivity for ethanol electrooxidation.•Promotion effect of catalysts should be attributed to the presence of AlOOH.•Durability of PtAl-based catalyst was evaluated in both media.
PDF
