Decoding Natural Strategy: Oxygen-Evolution Reaction on the Surface of Nickel Oxyhydroxide at Extremely Low Overpotential.

Although nickel (hydr)oxides in the absence of other metal ions are conventionally deemed inefficient catalysts for the oxygen-evolution reaction (OER) under alkaline conditions, this study reveals that nickel oxyhydroxide displays an OER activity at the associated peak for Ni(II) to Ni(III) oxidation postcharge accumulation. This occurs with only 90-120 mV overpotentials (at a low current density) and a Tafel slope of 297 mV/decade in a 0.10 M KOH solution. In the initial seconds, the Faraday efficiency lingers at a relatively low 20%, which can be attributed to charge storage. Nonetheless, as the duration extends to reach the 200 s mark, the efficiency notably escalates, exceeding 80%. Additionally, a mechanism for the OER in this low-overpotential zone is proposed, grounded in our investigation of the Ni(II) to Ni(III) peak and the OER region through in situ Raman spectroscopy. Taking into account the quantity of oxygen generated and the concentrations of redox-active Ni ions in the region of the redox peak, a turnover frequency of at a potential of 4.3 × 10-4 s-1 at 1.37 V was calculated. The documented reduction in overpotential during the OER may be ascribed to the complex interplay between the process of the OER and charge accumulation. The convergence of these reciprocally influencing factors facilitates a notably low overpotential in the OER. Our findings bear substantial implications for developing highly efficient and stable electrocatalysts for the OER in water-splitting applications.

Unveiling the Oxygen Evolution Mechanism with FeNi (Hydr)oxide under Neutral Conditions.

Large-scale solar-driven water splitting is a way to store energy, but it requires the development of practical and durable oxygen evolution reaction (OER) catalysts. The present paper aims to investigate the mechanism of the OER, local pH, high-valent metal ions, limitations, conversions, and details during the OER in the presence of FeNi foam using in situ surface-enhanced Raman spectroscopy. This research also explores the use of in situ surface-enhanced Raman spectroscopy for detecting species on foam surfaces during the OER. The acidic media around the electrode not only limit the process but also affect the phosphate ion protonation and overall catalysis effectiveness. The study proposes that FeNi hydroxides serve as true catalysts for OER under neutral conditions, rather than FeNi phosphates. However, phosphate species remain crucial for proton transfer and water molecule adsorption. Changes observed in pH at the open-circuit potential suggest new insights concerning the coordination of Ni(II) to phosphate ions under certain conditions. By extrapolating the Tafel plot, the overpotential for the onset of OER was determined to be 470 mV. Furthermore, the overpotentials for current densities of 1 and 5 mA/cm2 were 590 and 790 mV, respectively. These findings offer valuable insights into the advancement of the OER catalysts and our understanding of the underlying mechanism for efficient water splitting; both are crucial elements for the purpose of energy storage.

Determination of melamine contamination in milk with various packaging: a risk assessment study.

Melamine is one type of monomer used as starting substance in manufacturing packaging lining in many countries worldwide. Environmental and food contamination is an issue constantly discussed. In the present study, the melamine content in milk samples with three package types was measured by HPLC/UV. Melamine is not a lipophilic compound. Therefore, the selected samples were low-fat milk. The melamine content in various packaged milk, including packet, polyethylene bags, and plastic packaging, is 790 ± 39.8, 50.7 ± 13, and 57.7 ± 24.54 ppb, respectively. According to the existing standards, the measured values in all the milk samples were lower than the permitted limits. The risk assessment for adults and children showed that the HQ value for both age groups was less than 1. Therefore, milk consumption will not pose a health risk in terms of contamination with melamine.

Dynamic Changes of an Anodized FeNi Alloy during the Oxygen Evolution Reaction under Alkaline Conditions.

An efficient and durable oxygen evolution reaction (OER) catalyst is necessary for the water-splitting process toward energy conversion. The OER through water oxidation reactions could provide electrons for H2O, CO2, and N2 reduction and produce valuable compounds. Herein, the FeNi (1:1 Ni/Fe) alloy as foam, after anodizing at 50 V in a two-electrode system in KOH solution (1.0 M), was characterized by Raman spectroscopy, diffuse reflectance spectroscopy (DRS), X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), high-angle annular dark-field imaging (HAADF)-scanning transmission electron microscopy (STEM) and used as an efficient and durable OER electrocatalyst in KOH solution (1.0 M). The overpotential for the onset of the OER based on extrapolation of the Tafel plot was 225 mV. The overpotentials for the current densities of 10 and 30 mA/cm2 are observed at 270 and 290 mV, respectively. In addition, a low Tafel slope is observed, 38.0 mV per decade, for the OER. To investigate the mechanism of the OER, in situ surface-enhanced Raman spectroscopy was used to detect FeNi hydroxide and characteristic peaks of H2O. Impurities in KOH can adsorb onto the electrode surface during the OER. Peaks corresponding to Ni(III) (hydr)oxide and FeO42- can be detected during the OER, but high-valent FeNi (hydr)oxides are unstable and reduce under the open circle potential. Metal hydroxide transformations during the OER and anion adsorption should be carefully considered. In addition, Fe3O4 may convert to γ-Fe2O3 during the OER. This study aims to offer logical perspectives on the dynamic changes that occur during the OER under alkaline conditions in an anodized FeNi alloy. These changes encompass variations in morphology, surface oxidation, the generation of high-valent species, and phase conversion during the OER.

4-Methylimidazole, a carcinogenic component in food, amount, methods used for measurement; a systematic review.

4-methylimidazole (4-MEI) is widely used industrially. This carcinogenic component has been reported in some types of food. It is usually produced by the caramelization process in food, drinks and caramel coloring. The possible mechanism for the formation of this compound in food is the Maillard reaction. In order to estimate the amount of substance 4-MEI in food, a systematic study was conducted. The selected keywords were 4-methylimidazole, 4-MEI, beverage, drink, meat, milk, and coffee. 144 articles were obtained from the initial search. The articles were evaluated and finally, the data of 15 manuscripts were extracted. Based on the data extracted from selected articles, the highest amount is reported in caramel color, coffee, and cola drinks. In 70% of the selected studies, the analytical method was based on liquid chromatography. In this method, there is no need for derivatization. SPE columns were used to extract samples in most manuscripts. According to per capita consumption, the most exposure to 4-MEI is through coffee. In high risk food products, regular monitoring with analytical methods with high sensitivity is recommended. Furthermore, most of the selected studies were about the validation method, so few samples were selected. It is recommended to design more studies with a high sample size to accurately evaluate this carcinogenic compound in food.

Oxygen-evolution reaction in the presence of cerium(IV) ammonium nitrate and iron (hydr)oxide: old system, new findings.

Solar fuel production by photosynthetic systems strongly relies on developing efficient and stable oxygen-evolution catalysts (OECs). Cerium(IV) ammonium nitrate (CAN) has been the most commonly used sacrificial oxidant to investigate OECs. Although many metal oxides have been extensively investigated as OECs in the presence of CAN, mechanistic studies were rarely reported. Herein, first, Fe(III) (hydr)oxide (FeOxHy) was prepared by the reaction of Fe(ClO4)3 and KOH solution and characterized by some methods. Then, changes in Fe oxide in the presence of CAN during the OER were tracked using in situ Raman spectroscopy, in situ X-ray absorption spectroscopy, in situ visible spectroscopy, and in situ electron paramagnetic resonance spectroscopy. FeOxHy in the presence of CAN and during the OER converted to γ-Fe2O3 and [Fe(H2O)6]3+, and a small amount of oxygen was formed. A maximum turnover frequency and turnover number of 10-6 s-1 and 1.3 × 10-3 mol(O2)/mol(Fe) (for half an hour) in the presence of CAN (0.20 M) and FeOxHy were observed.

The radionuclides contamination in eggs as an environmental marker: a systematic review.

Foods are contaminated with natural and man-made radionuclides. The aim of this systematic review was to determine the amount and type of radionuclides in eggs, as well as the biomarker capability of eggs. The research studies with keywords radionuclide, radioisotopes, contamination and egg were searched in PubMed, Scopus, and Science Direct databases, regardless of publication time. A number of 70 studies were obtained and only 13 articles were finally selected according to exclusion, inclusion criteria and quality assessment results. Studies which detected radionuclide in the hen eggs were selected. The highest frequency of radionuclides belonged to Ra-226 and Cs-137. The index of natural radionuclides is Ra-226 and the index of synthetic radionuclides is Cs-137. The local eggs, in addition to determining food contamination, can also be a good biomarker for identifying environmental contamination.

Acrylamide; a neurotoxin in popcorns: a systematic review and meta-analysis.

Acrylamide is a known neurotoxic compound for humans. Foods that have high concentrations of acrylamide need to be identified. One of the food products containing acrylamide is popcorn. Popcorn is an important source of snacks for children, especially students. The presented study is a systematic review and meta-analysis of the level of acrylamide in popcorn. The search was done in different databases with the keywords; acrylamide, popcorn, popped corn. 27 articles were found by searching various databases. After initial screening and full text evaluation, 8 articles were selected for systematic review and 6 articles for meta-analysis. The amount of acrylamide in this product was in the range of 1,017.7-106 µg/kg. Microwaved corn contains lower amounts of acrylamide than other methods of preparation. The type of popcorn also had an effect on the amount of acrylamide with Meta-regression. It was found that sweet popcorn contains higher amounts of acrylamide. The overall value of acrylamide concentration in popcorns was calculated to be 459.6 ± 220.3 µg/kg. This amount is high and requires measures to reduce the amount of acrylamide.

The amount and detection method of styrene in foods: A systematic review and meta-analysis.

The ingredients in food packaging migrate to the food inside. One of the most common compounds used for packaging of food is polystyrene. This systematic review aimed to investigate the level of styrene's pollution in food packed with polystyrene. The original articles include keywords styrene, polystyrene, food, contamination, pollution, "food packaging" were searched in Web of science, Medline, Scopus, and Science Direct. A total of 227 studies were achieved. The articles that did not meet the inclusion criteria were excluded with the initial evaluation. The quality assessment was conducted for full paper and finally data were extracted from 8 selected articles. Mata analysis, meta-regression, subgroup analysis, and publication bias was also conducted with comprehensive meta-analysis (CMA) software. Most of the examined samples were dairy products. The amount of fat in dairy products is an important factor in increasing the migration of styrene. The shelf life of product also had effect on migration of styrene. The overall average was estimated as 91.53 ± 26.18 µg/kg in food matrix. This amount is less than the permissible level. The results of meta regression showed that the type of food affects the pooled mean of styrene in the food. There was no publication bias for the selected articles.

Oxygen-Evolution Reaction by a Palladium Foil in the Presence of Iron.

Herein, we investigate the oxygen-evolution reaction (OER) and electrochemistry of a Pd foil in the presence of iron under alkaline conditions (pH ≈ 13). As a source of iron, K2FeO4 is employed, which is soluble under alkaline conditions in contrast to many other Fe salts. Immediately after reacting with the Pd foil, [FeO4]2- causes a significant increase in OER and changes in the electrochemistry of Pd. In the absence of this Fe source and under OER, Pd(IV) is stable, and hole accumulation occurs, while in the presence of Fe this accumulation of stored charges can be used for OER. A Density Functional Theory (DFT) based thermodynamic model suggests an oxygen bridge vacancy as an active site on the surface of PdO2 and an OER overpotential of 0.42 V. A substitution of Pd with Fe at this active site reduces the calculated OER overpotential to 0.35 V. The 70 mV decrease in overpotential is in good agreement with the experimentally measured decrease of 60 mV in the onset potential. In the presence of small amounts of Fe salt, our results point toward the Fe doping of PdO2 rather than extra framework FeOx (Fe(OH)3, FeO(OH), and KFeO2) species on top of PdO2 as the active OER sites.

Molecular and technical aspects on the interaction of serum albumin with multifunctional food preservatives.

Synthetic food preservatives like sodium acetate (SA), sodium benzoate (SB), potassium sorbate (PS) and Butyl paraben (BP) have been widely used in food and pharmacy industries. One of the toxicological aspects of food additives is evaluation of their interaction with serum proteins such as albumin. These additives interaction with human serum albumin (HSA) can exert considerable effect on the absorption, distribution, metabolism and toxicity of chemical compounds. It should be noticed that the aforementioned food preservatives intake increase mainly in the presence of glucose may lead to complex formation of SA, SB, PS and BP with HSA and accelerate the development of variety disease such as cancer, diabetes, multiple sclerosis, brain damage, nausea and cardiac disease. Therefore, to understand the mechanisms of aforementioned food additives interaction and conformational changes of proteins, we aim to review various studies that investigated albumin interaction with these additives using several procedures.

Can clonidine as a pre-anaesthetic drug decrease bleeding during rhinoplasty surgery?

Clonidine is an antihypertensive drug which acts through facilitation of Alph-2 post-synaptic receptors and in addition to its antihypertensive, anti-anxiety and analgesic effects, its beneficial effects in reducing the bleeding during Neurosurgery and Orthopedics surgeries, delicate surgeries of ear and nasal and sinus endoscopy have been proved. In this study we discuss the effects of this drug in reducing bleeding during rhinoplasty surgery. A double-blinded clinical trial 80 patients have been conducted 40 patients received 5 µg/Kg of oral Clonidine, and 40 patients where placebo. The patients after surgery were divided into 4 groups according to the number of bloody standard gauzes during the surgery. Group 1(less than 2 bloody gauzes), group 2(2-3 bloody gauzes), group 3(4-5 bloody gauzes), group 4(more than 5 bloody gauzes). All the graded achieved results were analyzed using Chi-Square test and Fisher test. Mean and standard deviation (SD) of the amount of bleeding in the group who were receiving Clonidine were less than the witness group. Number of the patients in groups 3 and 4 for those who were receiving Clonidine was obviously fewer (1.8 ± 0.04 vs. 3.1 ± 0.05), (P < 0.05). Oral Clonidine as a pre-anesthetic drug causes decrease in bleeding during rhinoplasty surgery.