Ferric Compounds

The derivative from sucrose was prepared by substituting hydroxyl groups with chlorine. Identification of the modified sucrose was performed using the following analysis: Thin Layer chromatography (TLC), high performance liquid chromatography (HPLC), H-NMR, mass spectroscopy (MS), Inferred 1 spectroscopy (IR), melting point, OH groups. Moreover, some physical properties including: melting point, viscosity, surface tension and solubility.

The study has investigated the feasibility of using siderite-coated quartz sand and/or hematite-coated quartz sand columns for removing As from water. Arsenic-spiked tap water and synthetic As solution with As concentrations from 200 to 500 μg/L were used for the experiments. Since three coating methods employed to prepare siderite-coated quartz sand and hematite-coated quartz sand had no significant impact on As adsorption in batch tests, the column fillings were produced by means of the simplest one involving mechanically mixing the Fe mineral with quartz sand. Fixed bed tests show that the combination of siderite-coated quartz sand and hematite-coated quartz sand greatly promoted the column performance in removing As and the presence of As(III) in the influent improved the removal efficiency of the column. The relatively low capacity in treating As-spiked tap water arose from the suppression of FeCO 3 dissolution in the presence of high HCO 3 − concentration (333 mg/L), which consequently limited the formation of fresh Fe(III) oxides. However, the H 2 O 2 -conditioning greatly increased As adsorption capacity of the column for remediating As-spiked tap water. The Toxicity Characteristic Leaching Procedure (TCLP) test shows that the spent adsorbents were not hazardous and could be safely disposed of to landfill.

IntroductionObtaining hemostasis in the surgical crypt during periradicular surgery is essential. It allows for improved visibility and contributes to a dry environment suitable for the placement of moisture-sensitive root-end filling material. Although current materials may not be moisture sensitive during setting, hemostasis is important for proper placement of root-end filling materials during apical surgery. A new hemostatic agent, HemCon dental

supplementation in haemodialysis patients. No significant adverse reactions to iron therapy were observed. Background. The aim of this prospective study was to test a new protocol for iron supplementation in haemo-Key words: erythropoietin; ferritin; haemodialysis; iron; dialysis patients, as well as to assess the utility of intravenous different iron metabolism markers in common use and their 'target' values for the correction of iron deficiency. Methods. Thirty-three of 56 chronic haemodialysis patients were selected for long-term (6 months) i.v. Introduction iron therapy at 20 mg three times per week postdialysis based on the presence of at least one of the With the widespread utilization of rHuEpo in haemofollowing iron metabolism markers: percentage of dialysis, prolonged or chronic iron overload and transferrin saturation (%TSAT) <20%; percentage of haemosiderosis have almost disappeared. Eryhypochromic erythrocytes (%HypoE) >10% and thropoietin promotes the use of iron deposits in the serum ferritin (SF) <400 mg/l. Reasons for patient bone marrow, and consequently iron deficiency is a exclusion were active inflammatory or infectious disfrequent problem resulting in resistance to the full eases, haematological diseases, psychosis, probable effect of rHuEpo. It is well known that a negative iron iron overload (SF Á400 mg/l) and/or acute need of balance may occur-up to 2 g/year [1]-and it is not blood transfusion mostly due to haemorrhage and well established whether there is a compensatory change in renal replacement treatment. increase in intestinal absorption in haemodialysis Results. More than half (51.8%) of the patients of our patients when they are iron deficient [2-5]. Oral dialysis centre proved to have some degree of iron supplementation is plagued by poor patient adherence deficiency in spite of their regular oral iron due to frequent side-effects, and interference of other supplementation. At the start of the study the mean medication with the digestive absorption [6 ]. Several haemoglobin was 10.8 g/dl and increased after the 6 studies have demonstrated the utility of i.v. iron months of iron treatment to 12.8 g/dl (P<0.0001). supplementation in correcting anaemia and sparing The use of erythropoietin decreased from 118 rHuEpo [7-10]. However the multiple publications units/kg/week to 84 units/kg/week. The criterion for evaluating the criteria to detect and to treat patients iron supplementation with the best sensitivity/specifiwith iron deficiency and the several protocols adopted city relationship (100/87.9%) was ferritin <400 mg/l. to correct this situation clearly show that there is no Patients with ferritin <100 mg/l and those with ferritin consensus [11-18]. between 100 mg/l and 400 mg/l had the same increase We administered 20 mg iron i.v. post-dialysis on a in haemoglobin but other parameters of iron metabollong-term basis because it allows approximated conism were different between the two groups. tinuous availability of iron to be incorporated into Conclusions. Routine supplementation of iron in haemoglobin under the action of rHuEpo and allowed haemodialysis patients should be performed intraveneasy control to prevent the oversaturation of transferously. Target ferritin values should be considered indirin [19,20] and iron overload. vidually and the best mean haemoglobin values were We evaluated rHuEpo dose and haemoglobin during achieved at 6 months with a mean ferritin of 456 mg/l long-term i.v. iron therapy for 6 months and evaluated (variation from to 919 mg/l). The percentage of transthe best markers to monitor this therapy. Prior to this ferrin saturation, percentage of hypochromic erythrostudy, iron status was assessed on a 3-month basis by cytes and ferritin <100 mg/l, were not considered serum ferritin (SF) and the percentage of transferrin useful parameters to monitor routine iron saturation (%TSAT); iron supplementation was given orally as a routine and the i.v. route was reserved for

Zeolite matrix FAU is applied as an effective support that can be readily exchanged with ferric ions simply by wet ion exchange. The high exchange degree in this zeolite (USY) probably benefits from its larger channel dimension, which makes the diffusion of hydrated ferric ions into the channels easier. The as-prepared and subsequently calcined Fe-USY samples contain various kinds of iron species, which enable Fe-USY to efficiently decompose N 2 O to N 2 and O 2 . The presence of O 2 (20%), H 2 O (2%), or both reduces the N 2 O conversion only to a small extent at the same temperature. To test the feasibility and the catalytic activity in a practical situation, we prepared a monolithic Fe-USY/cordierite sample and investigated the N 2 O conversion under similar conditions. Such a cordieritesupported Fe-USY catalyst (∼9 wt % USY and 0.5 wt % Fe) shows the catalytic performance in N 2 O decomposition similar to the pure Fe-USY catalyst. Remarkably, both the pure Fe-USY and Fe-USY/cordierite catalysts demonstrate a very good durability because there is no activity lost after 100 and 144 h tests. Thus, the Fe-USY zeolite shows its potential as a cost-effective catalyst for N 2 O elimination in future applications.

The green nitrihemoglobin (R 2 2 tetramer, NHb) was prepared by the aerobic reaction of excess nitrite with human hemoglobin A 0 under mildly acidic conditions. A rate equation was determined and found to depend on nitrite, hydrogen ion, and oxygen concentrations:-d[HbNO 2 ]/dt) [k 1 + k 2 (K a [HNO 2 ])-[O 2 ] 1/2 ][HbNO 2 ], where k 1) (2.4 (0.9) × 10-4 s-1 , k 2) (1 (0.2) × 10 5 M-5/2 s-1 , and K a is the acid dissociation constant for nitrous acid (4.5 × 10-4 M). Also, the chemical properties of NHb are compared to those of the normal hemoglobin (including the addition products of common oxidation states with exogenous ligands, the alkaline transitions of the ferric forms, and the oxygen binding characteristics of the ferrous forms) and were found to be nearly indistinguishable. Therefore, the replacement of a single vinyl hydrogen with a nitro group on the periphery of each macrocycle in hemoglobin does not significantly perturb the interaction between the hemes and the heme pockets. Because nonphotochemical reaction chemistry must necessarily be most dependent on electronic ground states, it follows that the clearly visible difference in color between hemoglobin A 0 and NHb must be associated primarily with the respective electronic excited states. The possibility of NHb formation in vivo and its likely consequences are considered.

Previous studies have suggested that the conductive pili of Geobacter sulfurreducens are essential for extracellular electron transfer to Fe(III) oxides and for optimal long-range electron transport through current-producing biofilms. The KN400 strain of G. sulfurreducens reduces poorly crystalline Fe(III) oxide more rapidly than the more extensively studied DL-1 strain. Deletion of the gene encoding PilA, the structural pilin protein, in strain KN400 inhibited Fe(III) oxide reduction. However, low rates of Fe(III) reduction were detected after extended incubation (&gt;30 days) in the presence of Fe(III) oxide. After seven consecutive transfers, the PilA-deficient strain adapted to reduce Fe(III) oxide as fast as the wild type. Microarray, whole-genome resequencing, proteomic, and gene deletion studies indicated that this adaptation was associated with the production of larger amounts of the c-type cytochrome PgcA, which was released into the culture medium. It is proposed that the ...

Marine aerosols produced by bursting bubbles at the ocean surface are highly enriched in organic matter (OM) relative to seawater. The importance of this OM in the photochemical evolution of marine aerosols and particularly as a source of reactive oxidants are unknown but likely significant. To investigate oxidant production, nascent aerosols were generated by bubbling zero air through flowing Sargasso seawater and photochemical production of OH radical and hydroperoxide were quantified in aqueous extracts exposed to solar radiation. Extrapolation to ambient conditions indicates that OM photolysis was the primary in situ source for OH (1.1 x10 -8 M s -1 ) and hydroperoxides (1.7 x 10 -8 M s -1 ) in nascent aerosols; NO 3 photolysis was the primary source in aged, acidified aerosols (1.4×10 -7 and 4.1×10 -8 M s -1 , respectively). In situ OH photoproduction was comparable to gas-phase uptake whereas H 2 O 2 photoproduction was slower.

Magnetic tunnel junctions sandwiching a superlattice thin film of iron oxide nanocrystals (NCs) have been investigated. The transport was found to be controlled by Coulomb blockade and single-electron tunneling, already at room temperature. A good correlation was identified to hold between the tunnel magnetoresistance (TMR), the expected magnetic properties of the NC arrays, the charging energies evaluated from current-voltage curves, and the temperature dependence of the junction resistance. Notably, for the first time, a switching from negative to positive TMR was observed across the Verwey transition, with a strong enhancement of TMR at low temperatures.

In this study, laboratory experiments are conducted to compare the efficacy using several ozone-based advanced oxidation processes (AOPs), such as O 3 , O 3 /H 2 O 2 , and O 3 /UV, to treat landfill leachate. Raw leachate was initially coagulated by ferric chloride (FeCl 3 ) at the experimental-determined optimal dosage of 900 mg l À1 , and the ozone-based AOPs were subsequently applied. Results indicate that all AOPs would result in a significant increase on the ratio of BOD 5 /COD from 0.06 to 0.5 at the applied ozone dosage of 1.2 g l À1 . The increase on biodegradability for ozonated leachate indicates that these AOPs would be beneficial to the subsequent biological treatment process. To better explain the alteration of high organic molecules after oxidation, ultrafiltration was used to separate the leachate by several molecular weight cutoffs (MWCO). The COD distribution for coagulated leachate is 34% for MWCO > 10 kDa, 7% for MWCO between 5 and 10 kDa, 22% for MWCO between 1 and 5 kDa, and 37% for MWCO < 1 kDa. Following ozonation or AOPs, the predominant distribution of COD would be obviously shifted to the MWCO less than 1000 g mol À1 (72-85%) over the other MWCO ranges. In addition, Gel Permeation Chromatograph (GPC) analysis has showed a substantial agreement on the cleavage of larger organic compounds into smaller ones. O 3 /UV was found to be the most effective approach among these ozone-based AOPs to enhancing the biodegradability and eliminating the color of leachate.

Terephthalic acid (TPA) is widely applied as a raw material in making polyester fiber, polyethylene terephthalate (PET) bottles, polyester films, etc. TPA is toxic and is known to act as endocrine disruptor. TPA wastewater is traditionally treated by biological process and this study aims to evaluate the effectiveness of several advanced oxidation processes on TPA removal. The oxidation processes studied were: . The results indicate that the time required for the complete destruction of 50 ppm of TPA can be minimized from 10 h using UV-TiO 2 system, to less than 10 min by UV-H 2 O 2 -Fe-O 3 system. Some of the likely organic intermediates identified during TPA destruction include, benzoquinone, benzene, maleic acid and oxalic acid. Possible destruction pathway of TPA has been proposed. TPA degradation by various systems was also analyzed based on the reaction kinetics and operating costs.

Arsenic removal from natural well water from the state of Chihuahua (Mexico) is investigated by adsorption using a commercial activated carbon (AC). The latter is used as such, or after oxidation by several chemicals in aqueous solution: nitric acid, hydrogen peroxide, and ammonium persulphate. Raw and oxidised activated carbons are fully characterised (elementary analysis, surface chemistry, pore texture parameters, pH ZC , and TEM observation). Adsorption of As is measured in the aforementioned water, containing ca. 300 ppb of arsenic: removal of As is poor with the raw AC, and only the most oxidised carbons exhibit higher performances. By contrast, iron-doped ACs are much more efficient for that purpose, though their As uptake strongly depends on their preparation conditions: a number of samples were synthesised by impregnation of raw and oxidised ACs with HCl aqueous solutions of either FeCl 3 or FeCl 2 at various concentrations and various pH. It is shown that iron(II) chloride is better for obtaining high iron contents in the resultant ACs (up to 8.34 wt.%), leading to high As uptake, close to 0.036 mg As/g C. In these conditions, 100% of the As initially present in the natural well water is removed, as soon as the Fe content of the adsorbent is higher than 2 wt.%.

It is essential to determine the biodistribution, clearance, and biocompatibility of magnetic nanoparticles (MNPs) for in vivo biomedical applications to ensure their safe clinical use. We have studied these aspects with our novel iron oxide MNP formulation, which can be used as a magnetic resonance imaging (MRI) agent and a drug carrier system. Changes in serum and tissue iron levels were analyzed over 3 weeks after intravenous administration of MNPs to rats. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP) levels, and total iron-binding capacity (TIBC) were also measured with time to assess the effect of MNPs on liver function. Selected tissues were also analyzed for oxidative stress and studied histologically to determine biocompatibility of MNPs. Serum iron levels gradually increased for up to 1 week but levels slowly declined thereafter. Biodistribution of iron in various body tissues changed with time but greater fraction of the injected iron localized in the liver and spleen than in the brain, heart, kidney, and lung. Magnetization measurements of the liver and spleen samples showed a steady decrease over 3 weeks, suggesting particle degradation. Serum showed a transient increase in ALT, AST, AKP levels, and TIBC over a period of 6-24 h following MNP injection. The increase in oxidative stress was tissue dependent, reaching a peak at ∼3 days and then slowly declining thereafter. Histological analyses of liver, spleen, and kidney samples collected at 1 and 7 days showed no apparent abnormal changes. In conclusion, our MNPs did not cause long-term changes in the liver enzyme levels or induce oxidative stress and thus can be safely used for drug delivery and imaging applications.

The aims of this study were two fold; to develop magnetoliposomes (MLs) loaded with zinc phthalocyanine (ZnPc) complexed with cucurbituril (CB) (CB:ZnPc-MLs) and to evaluate their in vitro photodynamic (PD) and/or hyperthermia (HT) effects while using melanoma cells (B16-F10) as model. The liposomal formulations were characterized by both average diameter and zeta potential. The vesicle average size ranged from 150 to 200 nm and the polydispersity index (PdI) from 0.093 to 0.230. The zeta potential was significantly positive with values between 48 and 57 mV. The cell viability (CV) after PD and HT treatments was assessed by colorimetric MTT method. Melanoma cells were initially treated with the liposome formulation without light and magnetic field application, revealing cell viability not different from the control cells (p > 0.05). Photodynamic and hyperthermia assays were also applied separately, demonstrating that PD is more effective than HT in reducing the CV of the neoplastic cells. Combined application of both PD and HT treatments was even more effective in reducing the CV of B16-F10 cells. At the highest light dose (2 J/cm 2 ) and under magnetic field activation the CV was about half than PD applied alone. Therefore, the use of the photosensitizer-loaded magnetoliposome for combined photodynamic therapy (PDT) and magnetohyperthermia (MHT) application can be considered as a potential tool to treat malignant melanoma.

Background: Anemia is a common finding in heart failure (HF) patients and has been associated with increased morbidity and mortality. It is generally denominated as anemia of chronic disease (ACD), but the association with true ferropenic anemia is common. Many studies have investigated the effects of treating anemia in HF patients with either erythropoietin alone or combination of erythropoietin and intravenous iron. However, the effect of iron supplementation alone in HF patients with ACD, ferropenic anemia, or both is unknown. Methods and Results: IRON-HF study is a multicenter, investigator initiated, randomized, double-blind, placebo controlled trial that will enroll anemic HF patients with relatively preserved renal function, low transferrin saturation, low iron levels, and low to moderately elevated ferritin levels. Interventions are iron sucrose intravenously 200 mg once per week for 5 weeks, ferrous sulfate 200 mg by mouth 3 times per day for 8 weeks, or placebo. The primary objective is to assess the impact of iron supplementation (intravenously or by mouth) compared with placebo in HF patients with anemia from deficient iron availability. The primary end point is variation of peak oxygen consumption assessed by ergospirometry over 3-month follow-up. Secondary end points include functional class, brain natriuretic peptide levels, quality of life scores, left ventricular ejection fraction, adverse events, HF hospitalization, and death. Conclusions: The results of IRON-HF should help to clarify the potential clinical impact of mild to moderate anemia correction in HF patients. (J Cardiac Fail 2007;13:14e17)

Figure 4. (a) UV/Vis absorption spectra for Au nanoparticles, Fe 2 O 3, Au-Fe 2 O 3 nanoflakes, respectively; (b) IPCE, (c) band gap determination from a (i ph hu) 1/2 vs. photon energy (hu) plot, (d) photocurrent at 360 nm at applied potential of 1.5 V RHE in 1 m KOH solution for Fe 2 O 3 and Au-Fe 2 O 3 nanoflakes.

Polyamines are ubiquitous molecules, which, like iron, are essential for cell growth. All eukaryotic cells are equipped with a specific polyamine transport system (PTS). Polyamines have primary and secondary amino groups which chelate bivalent metal cations such as Fe and Cu. In the present study, we investigated the potential contribution of naturally occurring polyamines and their active transport system to iron uptake. In presence of subtoxic Fe(III) (10 mM), treatment of CHO cells with spermine, and to a lesser extent with spermidine (10-100 mM), resulted in a marked cytotoxic effect. This cytotoxicity was prevented by the addition of an iron-chelator, deferioxamine, and was not observed in CHO-MG cells, a mutant cell line devoid of polyamine transport activity. Experiments using 14 C-polyamines and 55 Fe(III) revealed that these toxic effects were related to polyamine-modulation of iron uptake, and were dependent on the presence of the active PTS. These results demonstrated active uptake of polyamine-iron complexes via the PTS. The number of amino groups affected the efficacy of the studied natural polyamines to transport iron via the PTS. Spermine, a tetramine, was more efficient than the triamine spermidine. Co-transport of iron by the diamine putrescine was not observed. These results demonstrate that the cell polyamine transport system is a potential cell entry pathway for iron. The studied polyamines, spermine and spermidine, may be components of the pool of transferrin-independent iron-chelating vectors, which have recently attracted the attention of many investigators.

Inhibition of intestinal α-amylase and α-glucosidase is an important strategy to regulate diabetes mellitus (DM). Antioxidants from plants are widely regarded in the prevention of diabetes. Fruits of Elettaria cardamomum (L.) Maton (Zingiberaceae) and Piper cubeba L. f. (Piperaceae) and flowers of Plumeria rubra L. (Apocynaceae) are traditionally used to cure DM in different countries. However, the role of these plants has been grossly under reported and is yet to receive proper scientific evaluation with respect to understand their traditional role in the management of diabetes especially as digestive enzymes inhibitors. Hence, methanol and aqueous extracts of the aforementioned plants were evaluated for their in vitro α-glucosidase and α-amylase inhibition at 1 mg/mL and quantification of their antioxidant properties (DPPH, FRAP tests, total phenolic and total flavonoids contents). In vitro optimization studies for the extracts were also performed to enhance in vitro biological ac...

Physico-chemical investigation on adsorption of congo red, an anionic azo dye by chitosan hydrobeads has been carried out. Adsorption process has been found to be dependant on temperature with optimum activity at 30 °C. Both ionic interaction as well as physical forces is responsible for binding of congo red with chitosan. Theoretical correlation of the experimental equilibrium adsorption data for congo red–chitosan hydrobeads system would be best explained by linearized form of Langmuir isotherm model. The kinetic results follow pseudo second-order rate equation. pH of the experimental solution influenced congo red adsorption inversely, and ∼20.0% of the dye could be desorbed from the loaded beads by changing the pH of the solution to alkaline range (∼pH 12.0). Both sodium chloride and sodium dodecyl sulfate significantly influenced the adsorption process.

Leaching tests, Fourier transform infrared spectroscopy (FTIR), extended X-ray absorption fine structure (EXAFS) spectroscopy, and thermodynamic modeling were performed to investigate arsenate [As(V)] immobilization mechanisms in iron hydroxide sludge stabilized with cement. The sludge from a groundwater remediation site in Tacoma, WA was mixed and immobilized with premixed cement to reach cement-to-sludge ratios of 2.5, 3.3, 5, 10, and 20 (wt premixed cement/wt dry sludge). The EXAFS analysis determined that As(V) formed bidentate mononuclear complexes on the iron hydroxide surface in the sludge. The adsorbed As(V) had a characteristic FTIR band at 830 cm -1 . Cement treatment converted the adsorbed As(V) to calcium arsenate precipitate with a FTIR peak at 860 cm -1 . The chemical forms of the As(V) were incorporated in an adsorption triple layer model (TLM) to describe the leaching behavior of As(V) in a pH range between 3 and 12. Cement treatment significantly reduced arsenic mobility because of the formation of the sparingly soluble calcium arsenate. ES021027G FIGURE 8. Model prediction and experimental results of As distribution in the treated sample (C/S ) 10). The experimental points are Ext TCLP results with 0.1 M Na2CO3. Carbonate was not present in the experimental systems and model calculations unless it is specified. (AsT ) 0.326 mM, FeT ) 5.25 mM, CaT ) 94 mM).

Background: In nature or in the laboratory, the roughly spherical interior of the ferritin protein is well suited for the formation and storage of a variety of nanosized metal oxy-hydroxide compounds which hold promise for a range of applications. However, the linkages between ferritin reactivity and the structure and physicochemical properties of the nanoparticle core, either native or reconstituted, remain only partly understood. Scope of review: Here we review studies, including those from our laboratory, which have investigated the structure of ferritin-derived ferrihydrite and reactivity of ferritin, both native and reconstituted. Selected proposed structure models for ferrihydrite are discussed along with the structural and genetic relationships that exist among several different forms of ferrihydrite. With regard to reactivity, the review will emphasize studies that have investigated the (photo)reactivity of ferritin and ferritin-derived materials with environmentally relevant gaseous and aqueous species. Major conclusions: The inorganic core formed from apoferritin reconstituted with varied amounts of Fe has the same structural topology as the inorganically derived ferrihydrite that is an important component of many environmental and soil systems. Reactivity of ferritin toward aqueous species resulting from the photoexcitation of the inorganic core of the protein shows promise for driving redox reactions relevant to environmental chemistry. General significance: Ferritin-derived ferrihydrite is effectively maintained in a relatively unaggregated state, which improves reactivity and opens the possibility of future applications in environmental remediation. Advances in our understanding of the structure, composition, and disorder in synthetic, inorganically derived ferrihydrite are shedding new light on the reactivity and stability of ferrihydrite derived artificially from ferritin.

A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (3,-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (3,-Fe203) by mild heat treatment and then to nanophase hematite (a-Fe203) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism for, the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxide and silicate phase surfaces. The reflectance spectrum of the clay-iron preparations in the visible range is generally similar to the reflectance curves of bright regions on Mars. This strengthens the evidence for the predominance of nanophase iron oxides/oxyhydroxides in Mars soil. The mode of formation of these nanophase iron oxides on Mars is still unknown. It is puzzling that despite the long period of time since aqueous weathering took place on Mars, they have not developed from their transitory stage to well-crystallized end-members. The possibility is suggested that these phases represent a continuously on-going, extremely slow weathering process. 20,831 20,832 BANIN ET AL.: NANOPHASE IRON MINERALS IN MA•S SOIL detection systems during the 1988-1990 oppositions [Bell et al., 1990; Roush et al., 1993; Singer et al., 1990]. Yet the mineralogical nature of the soil is far from being understood, nor are its time of formation and weathering processes known.

Various extracts of the aerial parts of Barkleyanthus salicifolius (Asteraceae) and Penstemon gentianoides (Scrophulariaceae) have been used in folk medicine to treat many ailments, particularly inflammation and migraine. Neither the bioactive components responsible nor the mechanisms involved have been evaluated. Here are reported antioxidant activities of their methanol, dichloromethane, and ethyl acetate extracts. Samples were evaluated for oxygen radical absorption capacity (ORAC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging, and inhibition of the formation of thiobarbituric acid reactive species (TBARS), a measure of lipid peroxidation. Antioxidant activities were strongly correlated with total polyphenol content. The most active extracts from P. gentianoides in scavenging DPPH radicals and inhibiting TBARS formation were the methanol extract (A) and a further ethyl acetate extract of this (E). Partition E was further divided into eight fractions, and both E and the fractions were compared for activity against butylated hydroxytoluene, quercetin, and tocopherol. Partition E and the most active fractions, 5 and 6, were found to have I 50 values of 14.1, 38.6, and 41.8 ppm, respectively, against DPPH and 18.5, 26.0, and 12.7 ppm, respectively, against TBARS formation. Consistent with this finding, partition E and fractions 4-6 had the greatest ORAC and FRAP values. These results show that these plants could be useful antioxidant sources.

With a model invertebrate animal we have assessed the fate of magnetic nanoparticles in biologically relevant media, i.e. digestive juices. The toxic potential and the internalisation of such nanoparticles by non-target cells was also examined. The aim of this study was to provide experimental evidence on the formation of Co 2+ , Fe 2+ and Fe 3+ ions from CoFe 2 O 4 nanoparticles in the digestive juices of a model organism. Standard toxicological parameters were observed. Cell membrane stability was tested with a modified method for assessment of cell membrane stability. Proton induced x-ray emission and low energy synchrotron radiation X-ray fluorescence was used to study internalisation and distribution of Co and Fe. Co 2+ ions were found to be more toxic than nanoparticles. We confirmed that Co 2+ ions are accumulated in the hepatopancreas but Fe n+ ions or CoFe 2 O 4 nanoparticles are not retained in vivo. A model biological system with a terrestrial isopod is suited to studies of the potential dissolution of ions and other products from metal-containing nanoparticles in biologically complex media.

Here we report a separation of a cationic dye, acridine orange (AO), by use of magnetic nanoparticles (␥-Fe 2 O 3 ). The particles were showed to capture 98% of the dye within the first 20 min of contact time. The maximum sorption capacity of the magnetic nanoparticles (MNPs) for AO was 59 mg/g. The sorption isotherms fit well with the Freundlich model. The sorption kinetics fits well the pseudo-second-order rate equation model. 60-90% dye recovery was achieved by rotary evaporating the dye bearing nanoparticles in acetone. The nanoparticles were recycled for additional dye removal.

A colloidal seeded-growth strategy, relying on time-programmed delivery of selected stabilizing surfactants, has been developed to synthesize bimagnetic hybrid nanocrystals (HNCs) that consist of a single-crystal tetrapod-shaped skeleton of ferrimagnetic (FiM) iron oxide functionalized with multiple polycrystalline spherical domains of ferromagnetic (FM) Co. Due to the direct bonding interfaces formed between the two materials at the relevant junction regions, the HNCs exhibit FiM-FM exchange coupling, which transcribes into a rich scenario of significantly modified properties (not otherwise achievable with any of the single components or with their physical mixtures), including higher saturation magnetization and coercitivity values, exchange biasing, and enhanced thermal stability due to induced extra anisotropy. The availability of these new types of HNCs suggests that development of appropriate synthetic tools for arranging distinct material domains in predetermined spatial arrangements could lead to a more rational design of nanoheterostructures potentially exploitable as active elements in future generations of magnetic recording devices.

A series of 1:1 iron(III) complexes of simple and sterically hindered tridentate 3N donor ligands have been synthesized and studied as functional models for catechol dioxygenases. All of them are of the type [FeLCl 3 ], where L is bis(pyrid-2-yl-methyl)amine (L1), N,N-bis(benzimidazol-2-ylmethyl)amine (L2), N-methyl-N 0 -(pyrid-2-ylmethyl)ethylenediamine (L3), N,N-dimethyl-N 0 -(pyrid-2-ylmethyl)-ethylenediamine (L4) and N-phenyl-N 0 -(pyrid-2-ylmethyl)ethylenediamine (L5). They have been characterised by spectral and electrochemical methods. The X-ray crystal structure of the complex [Fe(L4)Cl 3 ] has been successfully determined. The complex crystallizes in the triclinic space group P 1 with a = 7.250 °and Z = 2. It possesses a distorted octahedral geometry in which the L4 ligand is cis-facially coordinated to iron(III) and the chloride ions occupy the remaining coordination sites. The systematic variation in the ligand donor atom type significantly influences the Lewis acidity of the iron(III) center and hence the binding interaction of the complexes with simple and substituted catechols. The spectroscopic and electrochemical properties of the catecholate complexes generated in situ have been investigated. All the complexes catalyze mainly the oxidative intradiol cleavage of 3,5-di-tert-butylcatechol (H 2 DBC) in the presence of dioxygen, which is unexpected of the cis-facial coordination of the ligands. The rate of intradiol catechol cleavage reaction depends upon the Lewis acidity of iron(III) center and steric demand and hydrogen-bonding functionalities of the ligands. Interestingly, the electron-sink property of N-phenyl substituent in [Fe(L5)Cl 3 ] complex leads to enhancement in rate of cleavage. All these observations provide support to the substrate activation mechanism proposed for intradiol-cleaving enzymes.

The rate of photodegradation of two chelating agents, ethylenediaminetetraacetic acid (EDTA) and an isomeric mixture of ethylenediamine disuccinic acid (EDDS), was analysed in humic lake water and in distilled water using exposure to sunlight, and in the laboratory using lamps emitting UV radiation in the range 315±400 nm. Degradation was studied using Fe(III) complexes and sodium salts of chelates. Fe(III) complexes were illuminated at pH 3.1 and 6.5.

Hematite ( -Fe 2 O 3 ) nanoparticles were synthesized by the solid transformation of ferrous hydroxide and ferrihydrite in hydrothermal condition. The as-prepared -Fe 2 O 3 nanoparticles were characterized by UV-vis, PL, XRD, Raman, TEM, AFM, FESEM, and EDX analysis. The experimental results indicated the formation of uniform hematite nanoparticles with an average size of 45 nm and perfect crystallinity. The electrochemical behavior of a GC/ -Fe 2 O 3 electrode was studied using CV and EIS techniques with an electrochemical probe, [Fe(CN) 6 ] 3−/4− redox couple. The electrocatalytic activity was investigated toward DA oxidation in a phosphate buffer solution (pH 6.8) by varying different experimental parameters. The chronoamperometric study showed a linear response in the range of 0-2 M with LoD of 1.6 M for DA. Square wave voltammetry showed a linear response in the range of 0-35 M with LoD of 236 nM for DA.

With the use of different light and electron microscopic methods, we investigated the subcellular organization of afferent trigeminal terminals in the upper beak of the homing pigeon, Columba livia, which are about 5 m in diameter and contain superparamagnetic magnetite (SPM) crystals. The SPM nanocrystals are assembled in clusters (diameter, ϳ1-2 m). About 10 to 15 of these clusters occur inside one nerve terminal, arranged along the cell membrane. Each SPM cluster is embedded in a solid fibrous cup, open towards the cell surface, to which the cluster adheres by delicate fiber strands. In addition to the SPM clusters, a second inorganic iron compound has been identified: noncrystalline platelets of iron phosphate (about 500 nm wide and long and maximally 100 nm thick) that occur along a fibrous core of the terminal. The anatomic features suggested that these nerve endings could detect small intensity changes of the geomagnetic field. Such stimuli can induce deformations of the SPM clusters, which could be transduced into primary receptor potentials by mechanosensitive membrane receptor channels. The subepidermal fat cells surrounding the nerve endings prevent the inside from external mechanical stimuli. These structural findings corresponded to conclusions inferred from rock magnetic measurements, theoretical calculations, model experiments, and behavioral data, which also matched previous electrophysiologic recordings from migratory birds.

Background. The prevalence of micronutrient deficiencies in Cambodia is among the highest in Southeast Asia. Fortification of staple foods and condiments is considered to be one of the most cost-effective strategies for addressing micronutrient deficiencies at the population level. The Government of Cambodia has recognized the importance of food fortification as one strategy for improving the nutrition security of its population.

Neurodegerative diseases have been linked to oxidative stress arising from peroxidation of membrane biomolecules and high levels of Fe have been reported to play an important role in neurodegenerative diseases and other brain disorder. Malondialdehyde (MDA) is the end-product of lipid peroxidation and the production of this aldehyde is used as a biomarker to measure the level of oxidative stress in an organism. The present study compares the protective properties of two varieties of ginger [red ginger (Zingiber officinale var. Rubra) and white ginger (Zingiber officinale Roscoe)] on Fe2+ induced lipid peroxidation in rat brain in vitro. Incubation of the brain tissue homogenate in the presence of Fe caused a significant increase in the malondialdehyde (MDA) contents of the brain. However, the aqueous extract from both varieties of ginger caused a significant decrease in the MDA contents of the brain in a dose-dependent manner. However, the aqueous extract of red ginger had a significantly higher inhibitory effect on both Fe2+-induced lipid peroxidation in the rat brain homogenates than that of white ginger. This higher inhibitory effect of red ginger could be attributed to its significantly higher phytochemical content, Fe2+ chelating ability, OH

The possibility for an Al-superoxide complex to reduce Fe(III) to Fe(II), promoting oxidative damage through the Fenton reaction, is investigated using highly accurate ab initio methods and density functional theory in conjunction with solvation continuum methods to simulate bulk solvent effects. It is found that the redox reaction between Al-superoxide and Fe(III) to produce Fe(II) is exothermic. Moreover, the loss of an electron from the superoxide radical ion in the Al-superoxide complex leads to a spontaneous dissociation of molecular oxygen from aluminum, recovering therefore an Al 3+ hexahydrated complex. As demonstrated in previous studies, this complex is again prone to stabilize another superoxide molecule, suggesting a catalytic cycle that augments the concentration of Fe(II) in the presence of Al(III). Similar results are found for Al(OH) 2+ and Al(OH) 2 + hydrolytic species. Our work reinforces the idea that the presence of aluminum in biological systems could lead to an important pro-oxidant activity through a superoxide formation mechanism.

Magnetic Fe(OH) 3 @Fe 3 O 4 nanoparticles were successfully prepared and characterized. This magnetic nanocomposite was employed as an efficient, reusable, and environmentally benign heterogeneous catalyst for the direct amidation of alcohols with amine hydrochloride salts. Several derivatives of primary, secondary and tertiary amides were synthesized in moderate to good yields in the presence of this catalytic system. The catalyst was successfully recycled and reused up to six times without significant loss of its catalytic activity.