Unique activity of a Keggin POM for efficient heterogeneous electrocatalytic OER.

Polyoxometalates (POMs) have been well studied and explored in electro/photochemical water oxidation catalysis for over a decade. The high solubility of POMs in water has limited its use in homogeneous conditions. Over the last decade, different approaches have been used for the heterogenization of POMs to exploit their catalytic properties. This study focused on a Keggin POM, K6[CoW12O40], which was entrapped in a sol-gel matrix for heterogeneous electrochemical water oxidation. Its entrapment in the sol-gel matrix enables it to catalyze the oxygen evolution reaction at acidic pH, pH 2.0. Heterogenization of POMs using the sol-gel method aids in POM's recyclability and structural stability under electrochemical conditions. The prepared sol-gel electrode is robust and stable. It achieved electrochemical water oxidation at a current density of 2 mA/cm2 at a low overpotential of 300 mV with a high turnover frequency (TOF) of 1.76 [mol O2 (mol Co)-1s-1]. A plausible mechanism of the electrocatalytic process is presented.

Development of Meta-Chemical Surface by Dip-Pen Nanolithography for Precise Electrochemical Lead Sensing.

Dip-pen nanolithography (DPN) is a powerful and unique technique for precisely depositing tiny nano-spherical cap shapes (nanoclusters) onto a desired surface. In this study, a meta-chemical surface (MCS; a pattern with advanced features) is developed by DPN and applied to electrochemical lead sensing, yielding a calibration curve in the ppb range. An ink mixture of PMMA and NTPH (which binds to Pb (II), as supported by DFT calculations) is patterned over a Pt surface. The average height of the nanoclusters is ≈13 nm with a high surface area-to-volume ratio, which depends on the ink composition and the MCS surface. This ratio affected the sensitivity of the MCS as a detecting tool. The results indicate that the sensor's features can be controlled by the ability to control the size of the nanoclusters, attributed to the unique properties of the DPN production method. These results are significant for the water-source purification industry.

Heterogeneous Electrocatalytic Oxygen Evolution Reaction by a Sol-Gel Electrode with Entrapped Na3 [Ru2 (µ-CO3 )4 ]: The Effect of NaHCO3.

The Na3 [Ru2 (µ-CO3 )4 ] complex is acting as a water oxidation catalyst in a homogeneous system. Due to the significance of heterogeneous systems and the effect of bicarbonate on the kinetic, we studied the bicarbonate effect on the heterogeneous electrocatalyst by entrapping the Na3 [Ru2 (µ-CO3 )4 ] complex in a sol-gel matrix. We have developed two types of sol-gel electrodes, which differ by the precursor, and are demonstrating their stability over a minimum of 200 electrochemical cycles. The pH increases affected the currents and kcat for both types of electrodes, and their hydrophobicity, which was obtained from the precursor type, influenced the electrocatalytic process rate. The results indicate that NaHCO3 has an important role in the catalytic activity of the presented heterogeneous systems; without NaHCO3 , the diffusing species is probably OH- , which undergoes diffusion via the Grotthuss mechanism. To the best of our knowledge, this is the first study to present a simple and fast one-step entrapment process for the Na3 [Ru2 (µ-CO3 )4 ] complex by the sol-gel method under standard laboratory conditions. The results contribute to optimizing the WSP, ultimately helping expand the usage of hydrogen as a green and more readily available energy source.

Dual Role of Silicon-based Matrices in Electron Exchange Matrices for Waste Treatment.

Para chloro aniline (PCA) is a common toxic pollutant found in pharmaceutical wastewater. Our study suggests a novel PCA treatment method based on a heterogeneous advanced oxidation process (AOP) that proceeds in an electron exchange matrix (EEM) prepared by the incorporation of redox-active specie in silica matrices using the sol-gel synthesis route. The results, which are supported by DFT calculations, show that the silicon skeleton of the EEM has two important roles, both as a porous matrix that hosts the redox species and as an oxidant species involved in the AOP. The calculations indicate that the formation of a radical on the nitrogen is favored. The suggested mechanism could shed light on the AOP, which proceeds in a heterogenous system, and on its application inside the understudied EEMs that, until now, have been a virtual black box. A better understanding of the mechanism could lead to improved control over the heterogeneous processes that can play a critical role in industries with the need to treat small amounts of toxic compounds at low concentrations, such as in the pharmaceutical industry.

Metaphase Cells Enrichment for Efficient Use in the Dicentric Chromosome Assay.

The dicentric chromosome assay (DCA), is considered the 'gold standard' for radiation biodosimetry. Yet, DCA, as currently implemented, may be impractical for emergency response applications, especially when time is of the essence, owing to its labor-intensive and time-consuming nature. The growth of a primary lymphocyte culture for 48 h in vitro is required for DCA, and manual scoring of dicentric chromosomes (DCs) requires an additional 24-48 h, resulting in an overall processing time of 72-96 h for dose estimation. In order to improve this timing. we introduce a protocol that will detect the metaphase cells in a population of cells, and then will harvest only those metaphase cells. Our metaphase enrichment approach is based on fixed human lymphocytes incubated with monoclonal, anti-phosphorylated H3 histone (ser 10). Antibodies against this histone have been shown to be specific for mitotic cells. Colcemid is used to arrest the mitotic cells in metaphase. Following that, a flow-cytometric sorting apparatus isolates the mitotic fraction from a large population of cells, in a few minutes. These mitotic cells are then spread onto a slide and treated with our C-Banding procedure [Gonen et al. 2022], to visualize the centromeres with DAPI. This reduces the chemical processing time to ~2 h. This reduces the time required for the DCA and makes it practical for a much wider set of applications, such as emergency response following exposure of a large population to ionizing radiation.

Elucidation of a mechanism for the heterogeneous electro-fenton process and its application in the green treatment of azo dyes.

Vast efforts are directed today toward the development of efficient, green methods for the degradation of toxic compounds, especially those that are water-soluble. Though Fenton reactions are commonly used in wastewater treatment, their mechanisms and the active species involved remain obscure due to their mechanistic complexity. In this work, the mechanism of an electro-Fenton reaction, in which a FeLaO3 catalyst was entrapped in a sol-gel matrix, was studied in the presence of azo dyes as the model for toxic compounds. Increased knowledge about this important mechanism will confer greater control over related processes and enable a more efficient and green degradation method. DFT calculations showed that in the presence of Fe(IV), OH are formed under acidic conditions and that both the iron and hydroxyl species function as oxidation reagents in the degradation process. The structure of the formed Fe(IV) embedded in the solid matrix was not the typical tetravalent structure. Entrapment in the sol-gel matrix stabilized the catalyst, enhanced its efficiency and enabled it to be recycled. Sol-gel matrices constitute a simple method for the degradation of stable and toxic compounds under extreme pH conditions. The findings of this study are highly significant for the treatment of typically acidic wastewaters.

Advanced sol-gel process for efficient heterogeneous ring-closing metathesis.

Olefin metathesis, a powerful synthetic method with numerous practical applications, can be improved by developing heterogeneous catalysts that can be recycled. In this study, a single-stage process for the entrapment of ruthenium-based catalysts was developed by the sol-gel process. System effectiveness was quantified by measuring the conversion of the ring-closing metathesis reaction of the substrate diethyl diallylmalonate and the leakage of the catalysts from the matrix. The results indicate that the nature of the precursor affects pore size and catalyst activity. Moreover, matrices prepared with tetraethoxysilane at an alkaline pH exhibit a better reaction rate than in the homogenous system under certain reaction conditions. To the best of our knowledge, this is the first study to present a one-step process that is simpler and faster than the methods reported in the literature for catalyst entrapment by the sol-gel process under standard conditions.

Controlling the Size and Pattern Pitch of Ni(OH)2 Nanoclusters Using Dip-Pen Nanolithography to Improve Water Oxidation.

We use dip-pen nanolithography to accurately pattern Ni(OH)2 nanoclusters on a metachemical surface with an exceptionally large surface area. The distance between the nanoclusters can be manipulated to control the oxygen-evolution reaction current and overpotential, thereby improving the efficiency of the water-splitting process while using minute amounts of the catalyst.

Colostrum of Preeclamptic Women Has a High Level of Polyphenols and Better Resistance to Oxidative Stress in Comparison to That of Healthy Women.

Preeclampsia is a common pregnancy complication. Abnormal development of the placenta is the prevailing cause theory of this complication. Women with preeclampsia suffer from acute oxidative stress and high lipid oxidation in plasma. The aim of this study was to compare levels of polyphenols and lipid peroxidation in colostrum of nursing mothers with and without preeclampsia. The study was conducted at the Department of Obstetrics and Gynecology at Soroka University Medical Center. The study group consisting of 18 women, who were diagnosed with preeclampsia, was compared to the control group: 22 healthy women. The total phenolic content in the colostrum was determined by using the Folin-Ciocalteu method. Lipid peroxidation was determined by measuring MDA, using the TBARS assay. Polyphenol concentrations were significantly higher (about 33%) in the colostrum of the study group compared with the control group (p = 0.00042). Lipid peroxidation levels (MDA) were significantly lower (about 20%) in the colostrum of the study group compared with the control group (p = 0.03). Negative correlation was found between MDA concentration and the polyphenol level (R = -0.41, p = 0.02). In conclusion, we showed in this study a potential compensation mechanism that protects the newborn of a mother with preeclampsia from the stress process experienced by its mother.

Role of lycopene in preventing lipid peroxidation products, in commercial infant milk formula.

OBJECTIVES: The aim of the study was to investigate whether lycopene from natural sources (tomato extract) is able to protect newborns milk formula, against oxidative damage caused by exposure to hydroxyl radicals, and is there a difference between milk substitutes from various sources. METHODS: Four commercial brands of infant milk formula: two of the formulas were dairy milk (A-d and B-d) and two were based on soy bean vegan milk (A-s and B-s), were exposed to ionizing radiation radical (·OH). Lipid peroxidation was determined by measuring malondialdehyde (MDA) using thiobarbituric acid reactive substance test (TBARS). RESULTS: When suspensions containing the four brands of formula were subjected to oxidizing media produced by ionizing radiation (hydroxyl radicals), lipid peroxidation increased linearly as a function of the irradiation dose (R = 0.99). It was found that lycopene in a concentration of 0.6 mM, reduced the radiation damage only in the soy-based formula; decrease of ∼40% of the damage achieved in B-s, and ∼20% reduction in the damage caused to A-s, significantly p < 0.01. CONCLUSIONS: Lycopene in dairy milk did not protect against hydroxyl radicals; however, lycopene found to protect against hydroxyl radicals in soy milk. This result suggests different mechanisms of radical production that arises from high iron levels present in the soy milk and involving the high-valent iron peroxo species.

Salt Effect on the Antioxidant Activity of Red Microalgal Sulfated Polysaccharides in Soy-Bean Formula.

Sulfated polysaccharides produced by microalgae, which are known to exhibit various biological activities, may potentially serve as natural antioxidant sources. To date, only a few studies have examined the antioxidant bioactivity of red microalgal polysaccharides. In this research, the effect of different salts on the antioxidant activities of two red microalgal sulfated polysaccharides derived from Porphyridium sp. and Porphyridium aerugineum were studied in a soy bean-based infant milk formula. Salt composition and concentration were both shown to affect the polysaccharides' antioxidant activity. It can be postulated that the salt ions intefer with the polysaccharide chains' interactions and alter their structure, leading to a new three-dimensional structure that better exposes antiooxidant sites in comparison to the polysaccharide without salt supplement. Among the cations that were studied, Ca(2+) had the strongest enhancement effect on antioxidant activities of both polysaccharides. Understanding the effect of salts on polysaccharides' stucture, in addition to furthering knowledge on polysaccharide bioactivities, may also shed light on the position of the antioxidant active sites.

Plausible mechanisms of the fenton-like reactions, M = Fe(II) and Co(II), in the presence of RCO2(-) substrates: are OH(•) radicals formed in the process?

DFT calculations concerning the plausible mechanism of Fenton-like reactions catalyzed by Fe(II) and Co(II) cations in the presence of carboxylate ligands suggest that hydroxyl radicals are not formed in these reactions. This conclusion suggests that the commonly accepted mechanisms of Fenton-like reactions induced oxidative stress and advanced oxidation processes have to be reconsidered.

The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO3˙(-) as the active intermediate.

Kinetic and DFT results for the carbonate catalysed Co(H2O)6(2+) + H2O2 Fenton-like reaction suggest a mechanism involving the formation of a cyclic transient, cyclic-(CO4)Co(II)(OOH)(H2O)2(-) that decomposes into Co(II)(H2O)(OOH)(OH)2 + CO3˙(-), i.e. no OH˙ radicals are involved. Plausible biological implications are pointed out.

Three H2O2 molecules are involved in the "Fenton-like" reaction between Co(H2O)6²âº and H2O2.

Co(II) complexes and Co(H2O)6(2+) are used as catalysts in advanced oxidation processes. Therefore it was decided to study the kinetics of reaction of Co(H2O)6(2+) with H2O2. Surprisingly, the kinetic results point out that the process involves three consecutive reactions, each of them requiring an H2O2 molecule, i.e. three H2O2 molecules ligate to the central cobalt cation prior to the formation of radicals. DFT analysis suggests that the transient (H2O)3Co(II)(OOH)2(H2O2) decomposes via: (H2O)3Co(II)(OOH)2(H2O2) → (H2O)3Co(II)(OOH)(˙OOH)(OH) + ˙OH ΔG(0) = -5.975 kcal mol(-1), with no evidence for the formation of a Co(III) transient. It is proposed that analogous mechanisms are involved whenever the redox potential of the central cation is too high to enable the reaction: M(H2O)6(n+) + H2O2 → M((n+1)+)aq + ˙OH + OH(-).

Fatty acid composition of breastmilk of Israeli mothers.

We conducted this study to determine the fatty acid composition of breastmilk of Israeli women and compare it with baby milk substitutes. Samples of mature breast milk, from 29 lactating Israeli Jewish mothers were collected during feedings. Total milk lipids extracts were transmethylated and analyzed by using an improved gas-chromatographic method. About 72% of the total fatty acids in the investigated breast milk comprised oleic (18:1c; 31±4%), palmitic (16:0; 21±4%), and linoleic (18:2n-6; 20±4%) acids. Total saturated fatty acids represented 42±7% of total fatty acids. The monounsaturated fatty acids content was 33±5%, of which 94% was oleic acid, and the polyunsaturated fatty acids content was about 24±4%, of which 85% was linoleic acid. The a-linolenic acid level found in this study, 2.0±0.6%, was higher than the range of values reported for the world population (0.10-1.4%). The main fatty acids composition of the milk substitutes has very similar composition to the breast milk. Docosahexaenoic acid levels are particularly low among the population of Jewish nursing mothers in relation to the milk substitutes, containing docosahexaenoic acid in their formulations.

Saturated fatty acid composition of human milk in Israel: a comparison between Jewish and Bedouin women.

BACKGROUND: Breast milk is well established as the ideal source of nutrition for infants. Mature human breast milk generally contains 3.5-4.5% lipids comprising mostly triacylglycerols. In general, the fat composition of maternal human milk in developing countries shows higher levels of saturated fats, reflecting diets rich in carbohydrates. OBJECTIVES: To determine the profile of unsaturated fatty acids in the breast milk of two populations in southern Israel--urban Jewish and rural tent-dwelling Bedouin women. METHODS: This study involved 48 lactating Israeli mothers, 29 Jewish and 19 Bedouin (16-20 weeks postpartum), whose full-term infants were fed exclusively with breast milk. Total milk lipid extracts were transmethylated and analyzed by using an improved gas chromatographic method. RESULTS: The breast milk of the Bedouin women contained significantly higher levels of total major saturated fatty acids, lauric acid and palmitic acid (45.2 +/- 4.7% vs. 41.0 +/- 5.6%, P = 0.005; 5.2 +/- 2.1 vs. 6.8 +/- 2.0%, P = 0.03; and 22.7 +/- 2.4 vs. 20.6 +/- 3.8%, P = 0.02) respectively. No difference was found in the myristic acid level between the groups. The level of stearic acid was significantly higher in the Jewish group compared to the Bedouin group (5.7 +/- 1.1 vs. 5.1 +/- 1.1%, P = 0.04). There was a linear correlation between the levels of C14:0 and C12:0 in the Bedouin and lewish groups respectively (R = 0.87, R = 0.82, P < 0.001). CONCLUSIONS: Higher levels of saturated fatty acids were measured in the breast milk of Bedouin women, an economically weaker population. The results emphasize the importance of diet among lactating women and its influence on milk quality.

The Cu(I) catalyzed Meerwein reaction in aqueous solutions proceeds via a radical mechanism. The effect of several ligands.

The effect of the ligands 2,5,8,11-tetramethyl-2,5,8,11-tetraaza-dodecane and fumarate on the mechanism and kinetics of the Cu(I) catalyzed Meerwein reaction was studied. The results point out that initially the Cu(I) ion binds to the aromatic ring with the diazo substituent. This reaction is followed by a redox process involving N2 loss and the formation of an aryl radical, R˙. The following kinetics depends on the nature of the ligand, its effect on the redox potential and the steric hindrance it induces on the central copper ion. Clearly the ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraaza-dodecane does not form an optimal catalyst with Cu(I) while it does for the Ullmann reaction.

Electron exchange columns through entrapment of a nickel cyclam in a sol-gel matrix.

An electron exchange column (analogous to ion exchange columns) was developed using the unique redox properties of the nickel-tetraazamacrocyclic complexes (nickel cyclam [Ni(II)L(1)](2+)) and nickel-trans-III-meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, ([Ni(II)L(2)](2+)), and the physical and chemical stability of the ceramic materials using the sol-gel process to entrap the complexes. The entrapment by the biphasic sol-gel method is based on non-covalent bonds between the matrix and the complex; therefore the main problem was leaching. Parameters controlling the leaching were investigated. Redox cycles with the reducing agent ascorbic acid, and persulfate as the oxidizing agent were performed.

Role of radicals in the lipid peroxidation products of commercial infant milk formula.

Four commercial brands of infant milk formula were investigated, and the amount of shelf lipid peroxidation was determined by measuring malondialdehyde (MDA) or, more exactly, thiobarbituric acid reactive substance (TBARS) levels, which are the end products of lipid peroxidation. TBARS level, indicated by MDA concentration, was higher in the vegetarian brands. The vegetarian brands are, as expected, more prone to oxidation than dairy brands, as they contain more unsaturated fats. The introduction of formate anion diminishes the peroxide amounts initially present in the milk samples as well as those induced by radiation-induced oxidation.

Labor augmentation with oxytocin decreases glutathione level.

Objective. To compare oxidative stress following spontaneous vaginal delivery with that induced by Oxytocin augmented delivery. Methods. 98 women recruited prior to labor. 57 delivered spontaneously, while 41 received Oxytocin for augmentation of labor. Complicated deliveries and high-risk pregnancies were excluded. Informed consent was documented. Arterial cord blood gases, levels of Hematocrit, Hemoglobin, and Bilirubin were studied. Glutathione (GSH) concentration was measured by a spectroscopic method. Plasma and red blood cell (RBC) levels of Malondialdehyde indicated lipid peroxidation. RBC uptake of phenol red denoted cell penetrability. SPSS data analysis was used. Results. Cord blood GSH was significantly lower in the Oxytocin group (2.3 +/- 0.55 mM versus 2.55 +/- 0.55 mM, P = .01). No differences were found in plasma or RBC levels of MDA or in uptake of Phenol red between the groups. Conclusion. Lower GSH levels following Oxytocin augmentation indicate an oxidative stress, though selected measures of oxidative stress demonstrate no cell damage.