Electrochemical Bromination of Glycals

Herein, the convenient one-step electrochemical bromination of glycals using Bu4NBr as the brominating source under metal-catalyst-free and oxidant-free reaction conditions was described. A series of 2-bromoglycals bearing different electron-withdrawing or electron-donating protective groups were successfully synthesized in moderate to excellent yields. The coupling of tri-O-benzyl-2-bromogalactal with phenylacetylene, potassium phenyltrifluoroborate, or a 6-OH acceptor was achieved to afford 2C-branched carbohydrates and disaccharides via Sonogashira coupling, Suzuki coupling, and Ferrier rearrangement reactions with high efficiency. The radical trapping and cyclic voltammetry experiments indicated that bromine radicals may be involved in the reaction process.

An Investigation of Strontium Doped Erbium Oxide Nanoparticles for Enhanced Photocatalytic Degradation of Organic Pollutants in Aqueous Solution

A simple wet impregnation approach had been used to the successful preparation of different weight percentages of strontium/niobium doped Er2O3 nanoparticles. The X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (HR-TEM), Fourier transformed infrared spectroscopy (FTIR), and UV-visible (UV) spectroscopy was used to analyze the samples as they were prepared. With Sr and Nb doping at Er2O3 nanoparticles, the XRD patterns intensity was shifted, and its positioning was also shifted as weight percentages of doped were increased. Similarly, the lattice d spacing values were also decreased. According to HR-TEM images, Er2O3 seems to have a two-dimensional hexagonal nanoplate-like structure as well as being a few nm in size. The photocatalytic activities of pristine and Sr/Nb doped samples were evaluated against the methyl orange (MO) and rhodamine B (Rh B) dyes under UV-visible light irradiation. Within seventy-five minutes of UV-Visible light irradiation, the five-weight percentage of Sr doped Er2O3 nanoparticles shows significantly enhanced photocatalytic degradation efficiency against Rh B dye. The synergistic effect of the strong metal-support interaction between the Sr and Er2O3 nanoparticles could be attributed to the improved photocatalytic activity of the prepared samples. The cyclic stability and radical trapping experiments were also investigated against the same reaction conditions.

Rationally Designed Bi2M2O9 (M = Mo/W) Photocatalysts with Significantly Enhanced Photocatalytic Activity

Novel Bi2W2O9 and Bi2Mo2O9 with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi2WO6 and Bi2MoO6, the modified structure of Bi2W2O9 and Bi2Mo2O9 were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9 were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9. Photoluminescence (PL) and photocurrent indicated that Bi2W2O9 and Bi2Mo2O9 pose an enhanced ability of photogenerated electron–hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail.

Au@CoS-BiVO4 {010} Constructed for Visible-Light-Assisted Peroxymonosulfate Activation

A visible-light-Fenton-like reaction system was constructed for the selective conversion of peroxymonosulfate to sulfate radical. Au@CoS, when doped on monoclinic BiVO4 {010} facets, promoted spatial charge separation due to the different energy band between the m-BiVO4 {010} and {110} facets. The visible-light response of m-BiVO4 was enhanced, which was attributed to the SPR effect of Au. And the photogenerated electrons were transferred from the m-BiVO4 {010} facet to Au via a Schottky junction. Owing to higher work function, CoS was able to capture these photoelectrons with acceleration of the Co(Ⅱ)/Co(Ⅲ) redox, enhancing peroxymonosulfate conversion to sulfate radical (Co2+ + HSO5−→ Co3+ + •SO4− + OH−). On the other hand, holes accumulated on m-BiVO4 {110} facets also contributed to organics oxidation. Thus, more than 95% of RhB was degraded within 40 min, and, even after five cycles, over 80% of RhB could be removed. The radical trapping experiments and EPR confirmed that both the sulfate radical and photogenerated hole were the main species for organics degradation. UV-vis DRS, photoluminescence (PL) and photoelectrochemical analyses also confirmed the enhancement of the visible-light response and charge separation. In a pilot scale experiment (PMS = 3 mM, initial TOC = 151 mg/L, reaction time = 4 h), CoS-Au-BiVO4 loaded on glass fiber showed a high mineralization rate (>60%) of practical wastewater.

Methods to Determine Chain-Breaking Antioxidant Activity of Nanomaterials beyond DPPH•. A Review

This review highlights the progress made in recent years in understanding the mechanism of action of nanomaterials with antioxidant activity and in the chemical methods used to evaluate their activity. Nanomaterials represent one of the most recent frontiers in the research for improved antioxidants, but further development is hampered by a poor characterization of the ‘‘antioxidant activity’’ property and by using oversimplified chemical methods. Inhibited autoxidation experiments provide valuable information about the interaction with the most important radicals involved in the lipid oxidation, namely alkylperoxyl and hydroperoxyl radicals, and demonstrate unambiguously the ability to stop the oxidation of organic materials. It is proposed that autoxidation methods should always complement (and possibly replace) the use of assays based on the quenching of stable radicals (such as DPPH• and ABTS•+). The mechanisms leading to the inhibition of the autoxidation (sacrificial and catalytic radical trapping antioxidant activity) are described in the context of nanoantioxidants. Guidelines for the selection of the appropriate testing conditions and of meaningful kinetic analysis are also given.

Photocatalytic degradation of tetracycline by Phosphorus-doped carbon nitride tube combined with peroxydisulfate under visible light irradiation

Photocatalysis has been regarded as a kind of environmentally friendly advanced oxidation process to eliminate pollutants. In this work, Phosphorus-doped carbon nitride tube (PCN) was synthesized via a hydrothermal calcination method and applied to degrade tetracycline (TC) through combing with peroxydisulfate (PDS) under visible light irradiation. Experimental results showed that the optimized catalysts PCN-5 exhibited superior degradation performance and reusability for TC degradation. 96.4% TC could be degraded for optimal PCN-5 with 0.3 g·L−1 catalysts and 1.0 g·L−1 PDS under visible light within 60 min. In addition, the degradation rate constant for TC of PCN + PDS + Vis system was still above 85% after five uses. Radical trapping experiment indicating that O2·− is the dominant radical for TC degradation. The findings of this work revealed the potential application of the PCN + PDS + Vis system toward degrading contaminants in wastewater.

Absolute Antioxidant Activity of Five Phenol-Rich Essential Oils

Essential oils (EOs) have promising antioxidant activities which are gaining interest as natural alternatives to synthetic antioxidants in the food and cosmetic industries. However, quantitative data on chain-breaking activity and on the kinetics of peroxyl radical trapping are missing. Five phenol-rich EOs were analyzed by GC-MS and studied by oxygen-uptake kinetics in inhibited controlled autoxidations of reference substrates (cumene and squalene). Terpene-rich Thymus vulgaris (thymol 4%; carvacrol 33.9%), Origanum vulgare, (thymol 0.4%; carvacrol 66.2%) and Satureja hortensis, (thymol 1.7%; carvacrol 46.6%), had apparent kinh (30 °C, PhCl) of (1.5 ± 0.3) × 104, (1.3 ± 0.1) × 104 and (1.1 ± 0.3) × 104 M−1s−1, respectively, while phenylpropanoid-rich Eugenia caryophyllus (eugenol 80.8%) and Cinnamomum zeylanicum, (eugenol 81.4%) showed apparent kinh (30 °C, PhCl) of (5.0 ± 0.1) × 103 and (4.9 ± 0.3) × 103 M−1s−1, respectively. All EOs already granted good antioxidant protection of cumene at a concentration of 1 ppm (1 mg/L), the duration being proportional to their phenolic content, which dictated their antioxidant behavior. They also afforded excellent protection of squalene after adjusting their concentration (100 mg/L) to account for the much higher oxidizability of this substrate. All investigated EOs had kinh comparable to synthetic butylated hydroxytoluene (BHT) were are eligible to replace it in the protection of food or cosmetic products.

Excellent Photocatalytic Rhodamine B Degradation for water Remediation Over Pr3+ Doped Bi2WO6 Microspheres

In this work, a serious of Pr3+ doped Bi2WO6 had been prepared by one-step hydrothermal method without using any additive. XRD results showed that the Pr3+ doped Bi2WO6 possessed pure orthorhombic phase. XRD patterns shifted to higher angles with the doping amount of Pr3+ increasing indicated that Pr3+ was doped into the lattice of Bi2WO6. UV-vis DRS results revealed that the band gap was narrowed by Pr3+ doping. SEM and TEM images showed that the Pr3+ doped Bi2WO6 presented 3D flower-like microspheres constructed by many nanosheets. The photocatalytic activities of the as-prepared samples were evaluated by using rhodamine B (RhB) as the target organic pollutant. It was found that 1% Pr-Bi2WO6 exhibited excellent photocatalytic performance, as well as good stability and reusability. The improved photocatalytic activity can be ascribed to the optimum optical absorption activity, the larger specific surface area and the morphology of microspheres which resulted in the effective separation of the photogenerated electron hole pairs. In addition, the photocatalytic mechanism had been discussed according to the radical-trapping experiments.

Ferropsis cell death can cause complications that may be difficult to detect and quantify: autophagy role and possible therapeutics

It is possible to understand both the processes of ferroptosis and how this type of cell death will be harnessed in the near future. The novel ferroposis-based therapies will also be created and evaluated using various biomarkers. Selenium and vitamin E have been shown to support some types of cancer in several studies. Such environmental factors should be accounted for while exploring ferroaptosis's duties. The effect of these modifications will be dictated by the cellular and environmental context in which they are created. It is critical to determine whether the inhibitor can act as a lipophilic radical-trapping antioxidant and prevent ferroPTosis independently of the enzyme under investigation, as several studies with lipoxygenases have shown.Using pharmacological approaches to evaluate ferropsosis can have potential side effects that are difficult to measure. Using small-molecule probes may be investigated using small-molecules probes. It's essential to utilize a biochemical test or a pharmacodynamic marker of target inhibition when employing RSL3 to inhibit GPX4, or when using erastin to inhibit the system xc–cystine/glutamate antiporter, or by using an Xc–Cystine/Glutamate/Glutamic antiporter inhibitor, or an erast inhibitor, to inhibit Gpx4, GSH, and other types of protein thiols, such as GSH and protein thiola. Many tiny molecules that are potent and selective probes in cellular assays have limited applicability in animal studies. RSL3, a poor solubility, is useful only in instances when an injection is made directly into tissues or tumors. Interfering with iron to modulate ferroptosis has far-reaching ramifications. Findings obtained with iron chelators only should be interpreted with caution as depleting iron can have other side effects other than ferroPTosis suppression.