Characterization and properties of metallic iron nanoparticles: spectroscopy, electrochemistry, and kinetics

There are reports that nano-sized zero-valent iron (Fe0) exhibits greater reactivity than micro-sized particles of Fe0, and it has been suggested that the higher reactivity of nano-Fe0 may impart advantages for groundwater remediation or other environmental applications. However, most of these reports are preliminary in that they leave a hostof potentiallysignificant(and often challenging) material or process variables either uncontrolled or unresolved. In an effort to better understand the reactivity of nano-Fe0, we have used a variety of complementary techniques to characterize two widely studied nano-Fe0 preparations: one synthesized by reduction of goethite with heat and H2 (Fe(H2)) and the other by reductive precipitation with borohydride (Fe(BH)). Fe(H2) is a two-phase material consisting of 40 nm alpha-Fe0 (made up of crystals approximately the size of the particles) and Fe3O4 particles of similar size or larger containing reduced sulfur; whereas Fe(BH) is mostly 20-80 nm metallic Fe particles (aggregates of <1.5 nm grains) with an oxide shell/coating that is high in oxidized boron. The FeBH particles further aggregate into chains. Both materials exhibit corrosion potentials that are more negative than nano-sized Fe2O3, Fe3O4, micro-sized Fe0, or a solid Fe0 disk, which is consistent with their rapid reduction of oxygen, benzoquinone, and carbon tetrachloride. Benzoquinone-which presumably probes inner-sphere surface reactions-reacts more rapidly with FeBH than Fe(H2), whereas carbon tetrachloride reacts at similar rates with FeBH and Fe(H2), presumably by outer-sphere electron transfer. Both types of nano-Fe0 react more rapidlythan micro-sized Fe0 based on mass-normalized rate constants, but surface area-normalized rate constants do not show a significant nano-size effect. The distribution of products from reduction of carbon tetrachloride is more favorable with Fe(H2), which produces less chloroform than reaction with Fe(BH).     

Microbiological characterization of randomly selected Portuguese raw milk cheeses with reference to food safety

Seventy raw milk cheeses made in different regions of Portugal, both hard and soft varieties, made with cow's, ewe's, or goat's milk or combinations of these, were sampled within their quoted shelf lives for microbiological safety. On the basis of the presence or numbers of Escherichia coli, E. coli O157, Staphylococcus aureus, Salmonella, and Listeria monocytogenes, cheeses were categorized as satisfactory, acceptable, unsatisfactory, or unacceptable and potentially hazardous. Twenty-two of the 70 cheeses were classified as satisfactory or acceptable. Thirty-seven of the cheeses were considered unsatisfactory because of the presence of E. coli, S. aureus, or both, while 11 of the cheeses were graded as unacceptable and potentially hazardous because of the presence of excessive numbers of S. aureus, E. coli, or L. monocytogenes and the presence of Salmonella in three of these. All cheeses graded as unacceptable and potentially hazardous were soft or semisoft cheeses made with ewe's and goat's milk, with the exception of two hard cheeses made with cow's milk. E. coli O157 was not detected in any of the cheeses. According to the present results, it seems that the presence or counts of pathogenic or indicator organisms in raw milk cheeses cannot be related to the processing conditions, milk type, or region of production.     

Characterization of copper adsorption onto an alginate encapsulated magnetic sorbent by a combined FT-IR, XPS, and mathematical modeling study

Copper adsorption onto calcium alginate encapsulated magnetic sorbent is studied in this paper. The objective of this study was to qualitatively and quantitatively elucidate the copper binding onto the sorbent. The adsorption increases from around 0 to almost 100% as the initial pH is increased from 2 to 5. A maximum adsorption capacity of 0.99 mmol g(-1) is achieved. The FT-IR and XPS studies show that the C-O in carboxyl group of alginate directly attaches to the copper ion that leads to most of the adsorption. A mathematical model is developed, and it includes ion exchange between the calcium and the copper, coordination reaction between the functional group and the copper, as well as surface complex formation between the iron oxide and the copper. The model is capable of describing and predicting effects of various key operational parameters on the adsorption process, such as initial pH, metal concentration, and dosage of sorbent.     

NADPH-dependent D-aldose reductases and xylose fermentation in Fusarium oxysporum

Two aldose (xylose) reductases (ARI and ARII) from Fusarium oxysporum were purified and characterized. The native ARI was a monomer with M(r) 41000, pI 5.2 and showed a 52-fold preference for NADPH over NADH, while ARII was homodimeric with a subunit of M(r) 37000, pI 3.6 and a 60-fold preference for NADPH over NADH. In this study, the influence of aeration and the response to the addition of electron acceptors on xylose fermentation by F. oxysporum were also studied. The batch cultivation of F. oxysporum on xylose was performed under aerobic, anaerobic and oxygen-limited conditions in stirred tank reactors. Oxygen limitation had considerable influence on xylose metabolism. Under anaerobic conditions (0 vvm), xylitol was the main product with a maximum yield of 0.34 mole of xylitol/mole of xylose while the maximum ethanol yield (1.02 moles of ethanol/mole of xylose) was obtained under aerobic conditions (0.3 vvm). When the artificial electron acceptor acetoin was added to an anaerobic batch fermentation of xylose by F. oxysporum, the ethanol yield increased while xylitol excretion was also decreased.     

Bisnaphthalimidopropyl Derivatives as Inhibitors of Leishmania SIR2 Related Protein 1

The NAD⁺‐dependent deacetylases, namely sirtuins, are involved in the regulation of a variety of biological processes such as gene silencing, DNA repair, longevity, metabolism, apoptosis, and development. An enzyme from the parasite Leishmania infantum that belongs to this family, LiSIR2RP1, is a NAD⁺‐dependent tubulin deacetylase and an ADP‐ribosyltransferase. This enzyme's involvement in L. infantum virulence and survival underscores its potential as a drug target. Our search for selective inhibitors of LiSIR2RP1 has led, for the first time, to the identification of the antiparasitic and anticancer bisnaphthalimidopropyl (BNIP) alkyl di‐ and triamines (IC₅₀ values in the single‐digit micromolar range for the most potent compounds). Structure–activity studies were conducted with 12 BNIP derivatives that differ in the length of the central alkyl chain, which links the two naphthalimidopropyl moieties. The most active and selective compound is the BNIP diaminononane (BNIPDanon), with IC₅₀ values of 5.7 and 97.4 μM against the parasite and human forms (SIRT1) of the enzyme, respectively. Furthermore, this compound is an NAD⁺‐competitive inhibitor that interacts differently with the parasite and human enzymes, as determined by docking analysis, which might explain its selectivity toward the parasitic enzyme.     

Varied Composition of Tocochromanols in Different Types of Bran: Rye,Wheat, Oat,Spelt, Buckwheat,Corn, and Rice

The profiles of tocopherol (T) and tocotrienol (T3) homologues in 37 samples of seven different types of bran (rye, wheat, oat, spelt, buckwheat, rice, and corn), available on the Polish market, were studied. Tocochromanols were identified and quantified by reverse phase-high-performance liquid chromatograph/fluorescence detector and reverse phase-ultra performance liquid chromatography-electrospray ionization/mass spectrometry. Only rice bran contained all eight tocochromanol types. Corn bran lacked β-T3; rye, wheat, oat, and spelt bran lacked γ-T3 and δ-T3; and buckwheat bran lacked β-T3, γ-T3, and δ-T3. In buckwheat and corn bran tocopherols predominated (98 and 78%, respectively); whereas rye, wheat, oat, spelt, and rice bran were rich in tocotrienols (78, 76, 66, 87, and 66%, respectively). The average total tocochromanol contents in the oat, corn, spelt, buckwheat, wheat, rye, and rice bran were 5.5, 16.2, 15.8, 14.7, 12.8, 10.7, and 9.1 mg/100 g of dry weight, respectively. Tocochromanol concentrations in samples of the same type bran from different sources varied considerably. Better labeling of bran products to reflect this variation would assist with control of vitamin E daily dietary requirements.     

Fatty acid accumulation in the different fractions of the developing corn kernel

In the food industry, the use of the oil is determined by the composition of fatty acids, and this is highly dependent on its natural origin. The fatty acid composition of whole corn kernel was determined in three varieties of corn (Astro, GH2547, and Local). Linoleic acid was the predominant fatty acid in the oil of Astro and Local at all collection dates, whereas it was the major fatty acid in the oil of GH2547 only between 40 and 60 days after pollination (DAP). The fatty acid accumulation in the endosperm, pericarp and germ fractions of the corn kernel during maturation was determined. The accumulation pattern of oil content was different in these three kernel fractions. The highest levels of oil content in the endosperm (2.2%), germ (34.3%) and pericarp (10.8%) fractions were detected at 20, 40 and 30 (DAP), respectively. The fatty acid accumulation patterns were different amongst the analysed kernel parts, indicating a numerous differences between the three corn kernel parts. Throughout the sampling periods, the endosperm fraction was distinguished by the highest and the lowest levels of oleic and linoleic acids, respectively. At all stages of kernel development, the pericarp fraction had the highest levels of total polyunsaturated fatty acids, which has numerous healthy applications. These results may be useful in the understanding of the potential source of the beneficial unsaturated fatty acids amongst the different fractions of the corn kernel during maturation.     

Protective effect of polyamine extract of salt stressed and sprouted soybean seeds against ethanol-induced gastric ulcer in rats

The anti-ulcer activity of polyamine extract (PAE) of salt stressed and sprouted soybean seeds against ethanol-induced gastric damage was investigated in a rat model. The contents of the polyamines putrescine (20.11%), spermidine (9.46%), and spermine (2.79%) in PAE were determined using HPLC. The anti-ulcer activity of the extract was compared with the effects of the reference drug omeprazole. Pre- and post-administration of PAE at doses of 10+10, 20, and 20+20mg/kg of body weight in conjunction with ethanol administration significantly protected ethanolinduced gastric damage. The levels of superoxide dismutase and glutathione in stomach tissues were significantly changed, when compared with an ethanol control group. Polyamine extract exhibited high protective effect against ulcer lesions and could be used to develop new anti-ulcer drugs.     

Vitamin E reduces cholesterol esterification and uptake of acetylated low density lipoprotein in macrophages

The effects of vitamin E on cholesteryl ester (CE) metabolism in 1774 cells were examined. Pretreatment of 1774 cells with vitamin E at concentrations above 50 μM significantly decreased acetylated low density lipoprotein (LDL)-induced incorporation of [¹⁴C]oleate into CF in cells in a dose-dependent manner. This was partly due to vitamin E Also significantly inhibiting the uptake of [³H]CE-labeled acetylated LDL by 1774 cells. A trend existed toward suppression of acyl-CoA:cholesterol acyltransferase (ACAT) activity in the cell lysate at high vitamin E concentration, but there was no effect on hydrolysis of CE. These data indicate that vitamin E reduces the uptake of modified LDL and suppresses ACAT activity, resulting in less cholesterol esterification in macrophages; a novel mechanism underlying the antiatherogenic properties of vitamin E.