Keywords ZnMn.sub.2O.sub.4; Organic acids; Degradation; Active species Highlights * Nanoparticles of ZnMn.sub.2O.sub.4 (ZMO) were synthesized by a hydrothermal method. * Degradation rate of orange II ...with ZMO and an organic acid was ~ 99.8% in 30 min. * The study might lead to an advanced oxidation technology of organic degradation. * Mn(III) was found to be the active species for organic pollutants degradation. Nanoparticles of ZnMn.sub.2O.sub.4 (ZMO) were synthesized by a hydrothermal method and were used in the degradation of organic pollutants with the aid of several organic acids. The degradation efficiency of ZMO significantly increased in the presence of organic acids. The degradation rate of orange II was about 99.8% in 30 min by ZMO/formic acid system, and its quasi-first-order degradation kinetic rate constant was 0.4112 min.sup.-1. The mechanism of degradation was hypothesized and verified by identification of active species. This study might lead to an advanced oxidation technology for the degradation of organic contaminants based on Mn(III) as the active species with strong oxidizing ability. Author Affiliation: (a) School of Environmental and Safety Engineering, Changzhou University, Jiangsu 213164, China (b) School of Environmental and Chemical Engineering, Nanchang University, Nanchang 330031, China (c) Jiangsu Key Laboratory of Oil-Gas Storage and Transportation Technology, Changzhou University, Jiangsu 213164, China (d) Department of Ecosystem Science and Management and Materials Research Institute, 204 Energy and Environment Laboratory, The Pennsylvania State University, University Park, PA 16802, USA * Corresponding authors. Article History: Received 19 January 2021; Revised 11 March 2021; Accepted 13 March 2021 Byline: Fang Zhu (a), Jianxin Chen (b,c), Jianfeng Ma (a,*), Sridhar Komarneni (d,*)
Changes in the quality of fruits and vegetables are influenced by such factors as temperature, humidity and the composition of the atmosphere in which the fruits and vegetables are stored. During ...transport, an additional factor is vibration stress. This can lead to mechanical damage of the fruits and vegetables, which leads to deteriorated quality and, in extreme cases, spoiling. In order to preserve the best possible quality of fruits and vegetables despite their prolonged transport, they are maintained in an unripe condition and are later subject to forced ripening before selling. The aim of our investigations was to perform an analysis of the influence of vibration stress on the chemical parameters of fruits (“Bluecrop” highbush blueberry and grape) related to the process of their ripening. The identified parameters were the pH level, the content of total soluble solids, overall sugar, reducing sugars and ascorbic acid. The results of the performed investigations allowed for determining the levels of energy supplied in the form of vibration to the produce causing significant changes in its chemical parameters, indicating its accelerated ripening, as well as the levels of energy that result in changes leading to product spoilage.
The development of natural antioxidants to replace synthetic compounds is attractive. Perilla frutescens leaves were proven to be rich in antioxidants. The extraction of antioxidants from Perilla ...leaves via ultrasonic-assisted extraction (UAE) based on choline chloride-based deep eutectic solvents (DESs) was studied. Firstly, several DESs were prepared, and their extraction effects were compared. Secondly, the extraction process was optimized by single-factor experiments and response surface methodology (RSM). Finally, the optimization results were verified and compared with the results of traditional solvent-based UAE. The effects of solvents on the surface cell morphology of Perilla frutescens leaves were characterized by scanning electron microscopy (SEM). Choline chloride-acetic acid-based DES (ChCl-AcA) extract showed a relatively high ferric-reducing antioxidant activity (FRAP) and 2,2-diphenyl-1-picrylhyldrazyl radical scavenging rate (DPPH). Under the optimal operating conditions (temperature 41 °C, liquid–solid ratio 33:1, ultrasonic time 30 min, water content 25%, ultrasonic power 219 W), the experimental results are as follows: DPPH64.40% and FRAP0.40 mM Fe(II)SE/g DW. The experimental and predicted results were highly consistent with a low error (<3.38%). The values of the DPPH and FRAP were significantly higher than that for the water, ethanol, and butanol-based UAE. SEM analysis confirmed that ChCl-AcA enhanced the destruction of the cell wall, so that more antioxidants were released. This study provides an eco-friendly technology for the efficient extraction of antioxidants from Perilla frutescens leaves. The cytotoxicity and biodegradability of the extract will be further verified in a future work.
In this investigation, 4-antipyrinecarboxaldhyde was reacted with methyl hydrazinecarbodithioate to afford the carbodithioate derivative 3. The as-prepared carbodithioate derivative 3 is considered ...to be a key molecule for the preparation of new antipyrine-1,3,4-thiadiazole-based molecules (4–9) through its reaction with the appropriate hydrazonoyl halides. Furthermore, a typical Biginelli three-component cyclocondensation reaction involving ethyl acetoacetate, 4-antipyrinecarboxaldhyde, and thiourea under the standard conditions is carried out in the presence of sulfuric acid to afford the corresponding antipyrine–pyrimidine hybrid molecule (10). The latter was submitted to react with hydrazine monohydrate to provide the corresponding hydrazide derivative (11) which, under reaction with ethyl acetoacetate in refluxing ethanol containing catalytic amount of acetic acid, afforded the corresponding derivative (12). The structure of the newly synthesized compounds was affirmed by their spectral and microanalytical data. We also screened for their antimicrobial potential (ZOI and MIC) and conducted a kinetic study. Additionally, the mechanism of biological action was assessed by a membrane leakage assay and SEM imaging technique. Moreover, the biological activities and the binding modes of these compounds were further supplemented by an in silico docking study against E. coli β-carbonic anhydrase. The amount of cellular protein released by E. coli is directly correlated to the concentration of compound 9, which was found to be 177.99 µg/mL following treatment with 1.0 mg/mL of compound 9. This finding supports compound 9’s antibacterial properties and explains how the formation of holes in the E. coli cell membrane results in the release of proteins from the cytoplasm. The newly synthesized compounds represent acceptable antimicrobial activities with potential action against E. coli β-carbonic anhydrase. The docking studies and antimicrobial activity test proved that compound (9) declared a greater activity than the other synthesized compounds.
In this work, Bi.sub.4NbO.sub.8Cl associated with Bi.sub.24O.sub.31Cl.sub.10 and Bi.sub.3NbO.sub.7 was prepared by a solid-state method. During the removal of impurities, the heterostructure was ...formed simultaneously. The effect of acid on the type of heterostructure and photocatalytic performance of the prepared samples was studied. Under low-acetic acid concentrations, Bi.sub.4NbO.sub.8Cl/BiOCl/Nb.sub.2O.sub.5 composites could be obtained, while Bi.sub.4NbO.sub.8Cl/BiOCl was formed under high acidic conditions. Compared with the samples prepared by the solid-state method, the two types of heterojunctions Bi.sub.4NbO.sub.8Cl/BiOCl/Nb.sub.2O.sub.5 and Bi.sub.4NbO.sub.8Cl/BiOCl both showed improved photocatalytic performance. In particular, Bi.sub.4NbO.sub.8Cl/BiOCl/Nb.sub.2O.sub.5 prepared with ethanol/acetic acid ratio of 1:1 possessed the best photocatalytic activities, with RhB and CIP could be totally degraded within two hours, while the degradation rate of BPA was about 67% within three hours.
Boswellia serrata Roxb. extract (BSE), rich in boswellic acids, is well known as a potent anti-inflammatory natural drug. However, due to its limited aqueous solubility, BSE inclusion into an ...appropriate carrier, capable of improving its release in the biological target, would be highly desirable. Starting with this requirement, new hybrid composites based on the inclusion of BSE in a lamellar solid layered double hydroxide (LDH), i.e., magnesium aluminum carbonate, were developed and characterized in the present work. The adopted LDH exhibited a layered crystal structure, comprising positively charged hydroxide layers and interlayers composed of carbonate anions and water molecules; thus, it was expected to embed negatively charged boswellic acids. In the present case, a calcination process was also adopted on the LDH to increase organic acid loading, based on the replacement of the original inorganic anions. An accurate investigation was carried out by TGA, PXRD, FT-IR/ATR, XPS, SEM, and LC-MS to ascertain the nature, interaction, and quantification of the active molecules of the vegetal extract loaded in the developed hybrid materials. As a result, the significant disruption of the original layered structure was observed in the LDH subjected to calcination (LDHc), and this material was able to include a higher amount of organic acids when its composite with BSE was prepared. However, in vitro tests on the composites’ bioactivity, expressed in terms of antimicrobial and anti-inflammatory activity, evidenced LDH–BSE as a better material compared to BSE and to LDHc–BSE, thus suggesting that, although the embedded organic acid amount was lower, they could be more available since they were not firmly bound to the clay. The composite was able to significantly decrease the number of viable pathogens such as Escherichia coli and Staphylococcus aureus, as well as the internalization of toxic active species into human cells imposing oxidative stress, in comparison to the BSE.
The photoreduction of COsub.2 to other products containing carbon through simulated photosynthesis is a promising area of research. However, given the complexity of the COsub.2 photocatalytic ...reduction reaction, it is crucial to adjust the structure of the photocatalysts. The focus of this study was on creating NaOH-modified Bisub.2WOsub.6 nanosheet photocatalysts via a one-step hydrothermal route and using them to convert COsub.2 into CO through photocatalytic reduction under the condition of not using an electron sacrifice agent. The results of characterizations and activity data showed that adding an appropriate amount of NaOH significantly improved the photoreduction activity of COsub.2, as seen in the BWO-2 catalyst. The efficiency of photocatalysts could be improved by tuning the band structure through the addition of an appropriate amount of alkali. This adjustment improves the separation of photogenerated carriers and controls the concentration of oxygen vacancy to reduce recombination. As a result, the photocurrent activity is highly enhanced, leading to better reduction performance compared to unmodified photocatalysts. In experiments, the CO yield of the modified photocatalyst BWO-2 remained above 90 μmol/g after four trials, indicating its effectiveness in reducing COsub.2. This study offers insights into the regulation of band structure in bismuth-based photocatalysts for efficient COsub.2 reduction.
Proteus mirabilis urinary tract infections can lead to serious complications such as development of urinary stones. Lactobacillus spp., belonging to the natural microbiota of the urinary tract, ...exhibit a number of antagonistic mechanisms against uropathogens, including the secretion of organic acids. In this study, we determined the anti-adhesion, anti-cytotoxicity and anti-crystallization properties of the substances secreted by Lactobacillus. For this purpose, membrane inserts with a pore diameter 0.4 μm were used, which prevent mixing of cultured cells, simultaneously enabling the diffusion of metabolic products. The intensity of crystallization was assessed by measuring the levels of Casup.2+, Mgsup.2+ and NHsub.3 and by observing crystals using microscopic methods. The cytotoxicity of the HCV-29 cell line was determined using the LDH and MTT assays, and the impact of lactobacilli on P. mirabilis adhesion to the bladder epithelium was assessed by establishing CFU/mL after cell lysis. It was shown that in the presence of L. gasseri the adhesion of P. mirabilis and the cytotoxicity of the cells decreased. The degree of crystallization was also inhibited in all experimental models. Moreover, it was demonstrated that L. gasseri is characterized by the secretion of a high concentration of L-lactic acid. These results indicate that L-lactic acid secreted by L. gasseri has a significant impact on the crystallization process and pathogenicity of P. mirabilis.
Electrocatalytic reduction of COsub.2 to valuable chemicals can alleviate the energy crisis, and solve the greenhouse effect. The key is to develop non-noble metal electrocatalysts with high ...activity, selectivity, and stability. Herein, bimetallic metal organic frameworks (MOFs) materials (BiZn-MOF, BiSn-MOF, and BiIn-MOF) were constructed by coordinating the metals Zn, In, Sn, and Bi with the organic ligand 3-amino-1H-1,2,4-triazole-5-carboxylic acid (Hsub.2atzc) through a rapid microwave synthesis approach. The coordination centers in bimetallic MOF catalyst were regulated to optimize the catalytic performance for electrochemical COsub.2 reduction reaction (COsub.2RR). The optimized catalyst BiZn-MOF exhibited higher catalytic activity than those of Bi-MOF, BiSn-MOF, and BiIn-MOF. BiZn-MOF exhibited a higher selectivity for formate production with a Faradic efficiency (FE = 92%) at a potential of −0.9 V (vs. RHE, reversible hydrogen electrode) with a current density of 13 mA cmsup.−2. The current density maintained continuous electrolysis for 13 h. The electrochemical conversion of COsub.2 to formate mainly follows the *OCHO pathway. The good catalytic performance of BiZn-MOF may be attributed to the Bi-Zn bimetallic coordination centers in the MOF, which can reduce the binding energies of the reaction intermediates by tuning the electronic structure and atomic arrangement. This study provides a feasible strategy for performance optimization of bismuth-based catalysts.
