Heterogeneous reduction of PuO₂ with Fe(II): importance of the Fe(III) reaction product

Heterogeneous reduction of actinides in higher, more soluble oxidation states to lower, more insoluble oxidation states by reductants such as Fe(II) has been the subject of intensive study for more than two decades. However, Fe(II)-induced reduction of sparingly soluble Pu(IV) to the more soluble lower oxidation state Pu(III) has been much less studied, even though such reactions can potentially increase the mobility of Pu in the subsurface. Thermodynamic calculations are presented that show how differences in the free energy of various possible solid-phase Fe(III) reaction products can greatly influence aqueous Pu(III) concentrations resulting from reduction of PuO?(am) by Fe(II). We present the first experimental evidence that reduction of PuO?(am) to Pu(III) by Fe(II) was enhanced when the Fe(III) mineral goethite was spiked into the reaction. The effect of goethite on reduction of Pu(IV) was demonstrated by measuring the time dependence of total aqueous Pu concentration, its oxidation state, and system pe/pH. We also re-evaluated established protocols for determining Pu(III) {[Pu(III) + Pu(IV)] - Pu(IV)} by using thenoyltrifluoroacetone (TTA) in toluene extractions; the study showed that it is important to eliminate dissolved oxygen from the TTA solutions for accurate determinations. More broadly, this study highlights the importance of the Fe(III) reaction product in actinide reduction rate and extent by Fe(II).     

Determination of Pb(II) Ions Using Novel Ion-Imprinted Polymer Magnetic Nanoparticles: Investigation of the Relation Between Pb(II) Ions in Cow’s Milk and Their Nutrition

The application of novel Pb(II) ion-imprinted polymer coated on magnetic mesoporous silica was investigated in preconcentration and determination of low level of Pb(II) ions. The job proposed a new method for preconcentration and determination of Pb(II) ions. This novel sorbent was characterized by scanning electron microscopy, thermal gravimetric/differential thermal analysis, elemental analysis, and low-angle X-ray powder diffraction. Effects of various factors such as the effects of the pH of sample solution, eluent (include type, concentration and volume), adsorption and desorption time which are effective in method efficiency, were appraised through this study. In order to investigate the selectivity of this sorbent toward Pb(II) ion, the effects of variety of foreign ions interfering on preconcentration and recovery of Pb(II) ions were also investigated. The limit of detection (LOD) was found to be 0.7 μg L^?1 and the recovery and relative standard deviation of the method were 96.6–102.4 % and 1.3–3.3 %, respectively. Validation of the outlined method was performed by analyzing several standard reference materials with certified Pb(II) concentrations. Finally, this sorbent was applied for separation and determination of Pb(II) ion in grass and cow’s milk, which showed their lead concentration to be below the detection limit of flame atomic adsorption spectroscopy.     

Inhibitory effect of dissolved silica on H₂O₂ decomposition by iron(III) and manganese(IV) oxides: implications for H₂O₂-based in situ chemical oxidation

The decomposition of H(2)O(2) on iron minerals can generate ?OH, a strong oxidant that can transform a wide range of contaminants. This reaction is critical to In Situ Chemical Oxidation (ISCO) processes used for soil and groundwater remediation, as well as advanced oxidation processes employed in waste treatment systems. The presence of dissolved silica at concentrations comparable to those encountered in natural waters decreases the reactivity of iron minerals toward H(2)O(2), because silica adsorbs onto the surface of iron minerals and alters catalytic sites. At circumneutral pH values, goethite, amorphous iron oxide, hematite, iron-coated sand, and montmorillonite that were pre-equilibrated with 0.05-1.5 mM SiO(2) were significantly less reactive toward H(2)O(2) decomposition than their original counterparts, with the H(2)O(2) loss rates inversely proportional to SiO(2) concentrations. In the goethite/H(2)O(2) system, the overall ?OH yield, defined as the percentage of decomposed H(2)O(2) producing ?OH, was almost halved in the presence of 1.5 mM SiO(2). Dissolved SiO(2) also slowed H(2)O(2) decomposition on manganese(IV) oxide. The presence of dissolved SiO(2) results in greater persistence of H(2)O(2) in groundwater and lower H(2)O(2) utilization efficiency and should be considered in the design of H(2)O(2)-based treatment systems.     

Synchrotron micro-XRF and micro-XANES confirmation of the uptake and translocation of TiO₂ nanoparticles in cucumber (Cucumis sativus) plants

Advances in nanotechnology have raised concerns about possible effects of engineered nanomaterials (ENMs) in the environment, especially in terrestrial plants. In this research, the impacts of TiO(2) nanoparticles (NPs) were evaluated in hydroponically grown cucumber (Cucumis sativus) plants. Seven day old seedlings were treated with TiO(2) NPs at concentrations varying from 0 to 4000 mg L(-1). At harvest, the size of roots and shoots were measured. In addition, micro X- ray fluorescence (micro-XRF) and micro X-ray absorption spectroscopy (micro-XAS), respectively, were used to track the presence and chemical speciation of Ti within plant tissues. Results showed that at all concentrations, TiO(2) significantly increased root length (average >300%). By using micro-XRF it was found that Ti was transported from the roots to the leaf trichomes, suggesting that trichomes are possible sink or excretory system for the Ti. The micro-XANES spectra showed that the absorbed Ti was present as TiO(2) within the cucumber tissues, demonstrating that the TiO(2) NPs were not biotransformed.     

双硫腙修饰丝网印刷电极同时检测茶汤中的Cu(II)和Pb(II)

在乙酸-乙酸钠缓冲溶液(0.1 mol/L、pH 5.0)中,利用双硫腙修饰丝网印刷电极阳极溶出伏安法分别于-0.18 V、-0.76 V阳极溶出峰同时测定重金属离子Cu2+和Pb2+。通过优化测定条件,得到最佳参数为:双硫腙修饰量3μg、pH 5.0、富集电位-1.1 V、富集时间210 s。在此条件下,Cu2+和Pb2+浓度分别在1.0×10-10-1.0×10-5mol/L、1.0×10-10-1.0×10-6mol/L范围内与峰电流呈良好的线性关系(RCu=0.9991,RPb=0.9934),检测限分别为0.35×10-10mol/L、0.41×10-10mol/L。该方法简单、快速、灵敏,可用于检测茶汤中的Cu2+和Pb2+。     

Effects of surface heterogeneity on the adsorption of CO₂ in microporous carbons

Carbon capture combined with utilization and storage has the potential to serve as a near-term option for CO(2) emissions reduction. CO(2) capture by carbon-based sorbents and CO(2) storage in geologic formations such as coal and shale both require a thorough understanding of the CO(2) adsorption properties in microporous carbon-based materials. Complex pore structures for natural organic materials, such as coal and gas shale, in addition to general carbon-based porous materials are modeled as a collection of independent, noninterconnected, functionalized graphitic slit pores with surface heterogeneities. Electronic structure calculations coupled with van der Waals-inclusive corrections have been performed to investigate the electronic properties of functionalized graphitic surfaces. With Bader charge analysis, electronic structure calculations can provide the initial framework comprising both the geometry and corresponding charge information required to carry out statistical modeling. Grand canonical Monte Carlo simulations were carried out to determine the adsorption isotherms for a given adsorbent-adsorbate interaction at temperature/pressure conditions relevant to carbon capture applications to focus on the effect of the surface functionalities. On the basis of the current work, oxygen-containing functional groups were predicted to enhance CO(2) adsorption in microporous carbon materials in the absence of water vapor, and the hydrated graphite was found to hinder CO(2) adsorption.     

Aminoglycoside 3'‐phosphotransferase II (APH(3')II): Review of its safety and use in the production of genetically engineered plants

Calgene conducted a thorough review and analysis of the use of the kan^r gene and gene product, aminoglycoside 3'‐phosphotransferase II (APH(3')II), for use as a selectable marker in FLAVR SAVR? tomatoes, in BXN? cotton and oil‐modified rapeseed. The data generated support the conclusions that APH(3')II is not a toxin or allergen, that the kan ^r gene is highly unlikely to move from the plant genome into microorganisms via horizontal gene transfer, that if such transfer could occur the impact would be minimal, and that APH(3')II in transgenic plants will not compromise antibiotic use in humans or animals.

At FDA's Food Advisory Committee meeting on April 6–8, 1994, the FDA Center for Food Safety and Applied Nutrition (CFSAN) concluded that the FLAVR SAVR tomato was as safe and nutritious as other commonly consumed tomatoes and “that the use of the kan^r gene and APH(3')II will not have a significant impact on the environment and that an environmental impact statement is not required.”; On May 18, 1994, the FDA finished its safety review of the FLAVR SAVR tomato and APH(3')II. The FDA concluded that “FLAVR SAVR? tomatoes have not been significantly altered when compared to varieties of tomatoes with a history of safe use”; (Federal Register 59: 26646) and “that the use of aminoglycoside 3'‐phosphotransferase II is safe for use as a processing aid in the development of new varieties of tomato, oilseed rape, and cotton intended for food use”; (Federal Register 59: 26700).     

Sawdust of lam tree (Cordia africana) as a?low-cost, sustainable and easily available adsorbent for the removal of toxic metals like Pb(II) and Ni(II) from aqueous solution

Sawdust of lam tree (Cordia africana) has been investigated as an adsorbent for the removal of lead and nickel ions from aqueous solution. Since lam tree is widely grown in almost all the eastern, western, central and southern tropical African countries (United States Department of Agriculture, GRIN, Maryland), it can be a?common most easily available, sustainable, low cost adsorbent for the treatment of wastewaters in this part of the world where growing industrialization is affecting water quality like elsewhere in the world. Therefore, it is worthwhile to investigate the potential of sawdust of lam tree as an adsorbent for the removal of lead and nickel ions from aqueous solution as a?first step. The effect of contact time, pH, metal ion concentration and temperature on adsorption of these metal ions has been investigated to identify the optimum conditions for maximum adsorption. The equilibrium time was found to be 50?min for Pb⁺⁺ and 70?min for Ni⁺⁺ adsorption. Adsorption starts at a?low pH and increases steadily as the pH increases. The equilibrium adsorption data at temperatures of 25, 40 and 60°C were analyzed by the Langmuir and Freundlich isotherm models. Although equilibrium adsorption data conforms to both the models, the best fit was obtained with the Langmuir isotherm. Thermodynamic parameters like equilibrium constant, enthalpy change, free energy change, and entropy change were calculated and discussed. The maximum adsorption capacity of sawdust for Pb⁺⁺ and Ni⁺⁺ were calculated from the Langmuir isotherms. The metal uptake was found to increase with increase in temperature. The positive values of ??H ^o and negative values of ??G ^o together indicate that the adsorption of Pb⁺⁺ and Ni⁺⁺ on sawdust of lam tree is endothermic and spontaneous in nature. The study demonstrated that the sawdust of lam tree can be effectively used as an adsorbent for the removal of metal ions from aqueous solutions.     

Predominance of aqueous Tl(I) species in the river system downstream from the abandoned Carnoulès mine (Southern France)

Thallium concentration reached up to 534 μg L(-1) in the Reigous acid mine drainage downstream from the abandoned Pb-Zn Carnoule?s mine (Southern France). It decreased to 5.44 μg L(-1) in the Amous River into which the Reigous creek flows. Tl(I) predominated (>98% of total dissolved Tl) over Tl(III), mainly in the form of Tl(+). Small amounts of Tl(III) evidenced in Reigous Creek might be in the form of aqueous TlCl(2)(+). The range of dissolved to particulate distribution coefficients log K(d) = 2.5 L kg(-1) to 4.6 L kg(-1) indicated low affinity of Tl for particles, mainly ferrihydrite, formed in the AMD-impacted watershed. The low retention of Tl(+) on ferrihydrite was demonstrated in sorption experiments, the best fit between experimental and modeled data being achieved for surface complexation constants log K(ads) = -2.67 for strong sites and log K(ads) = -3.76 for weak sites. This new set of constants allowed reasonable prediction of the concentrations of aqueous and particulate Tl resulting from the mixing of water from Reigous Creek and the Amous River water during laboratory experiments, together with those measured in the Amous River field study.     

Formation of heterocyclic amine–amino acid adducts by heating in a model system

Although mutagenic and carcinogenic heterocyclic amines (HCAs) are known to be formed in cooked meat and fish, human HCA exposure and carcinogenic risk have not been elucidated in sufficient detail. In this work, we investigated the formations of HCA–amino acid adducts in a model system by using a liquid chromatography–mass spectrometry to elucidate another source of human HCA exposure. The 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) adduct with glycine was formed easily by heating at 200 °C within 5 min, which is probably based on the dehydration condensation of the amino group of PhIP and carboxyl group of glycine. PhIP and other HCAs such as 2-amino-3-methyl-3H-imidazo[4,5-f]quinolone, 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline and 3-amino-1,4-dimethyl-5H-pyrido[3,4-b]indole, also bound with various amino acids by heating. Among these amino acids, proline tends to form adducts with HCAs, but serine, cysteine and lysine hardly bound with HCAs. These results provided a basic understanding of the formation of HCA adducts with amino acids during cooking.     

Solid Phase Extraction of Pb(II) and Cd(II) in Food,Soil, and Water Samples Based on 1-(2-Pyridylazo)-2-Naphthol-Functionalized Organic–Inorganic Mesoporous Material with the aid of Experimental Design Methodology

An effective sorbent of 1-(2-Pyridylazo)-2-naphthol-functionalized mesoporous silica has been prepared to simultaneous separation and preconcentration of lead and cadmium ions in aqueous solution. Structural characterization of 1-(2-Pyridylazo)-2-naphthol-functionalized organic–inorganic hybrid mesoporous materials was conducted by Fourier transform infrared spectroscopy, transmission electron microscopy, N₂ adsorption–desorption measurement, X-ray diffraction, and elemental and thermal analysis, which confirmed the successful grafting of organic moiety on mesoporous silica. The affecting parameters on adsorption and desorption steps were optimized by Box-Behnken design through response surface methodology. Three variables (pH value, sorption time, and amount of the sorbent) were selected as the main factors affecting sorption step, while four variables (type of eluent, eluent volume, eluent concentration, and elution time) were selected for desorption step in the optimization study. The optimized values by this optimization method were 10 mg, 8 min, 6.3, HCl, 1.6 mL, 1.2 mol L^?l HCl, and 10 min, for amount of sorbent, sorption time, pH of solution, type, volume, and concentration of the eluent, and elution time, respectively. Under the optimized conditions, the detection limits of the proposed method for lead and cadmium ions were found to be 0.9 and 0.04 μg L^?1, respectively, while the relative standard deviation (RSD) for five replicate measurements was calculated to be <3 % for both ions. For proving that the proposed method is reliable, a wide range of food, soil, and water samples with different and complex matrixes was used.     

A Comparison of War Iconography in the Archaeological Textiles of Paracas-Topará (in Southern Peru) and in the Weavings of Ayllu Qaqachaka (Bolivia) Today

Abstract

Drawing on some observations by Anne Paul concerning the iconography of textile borders in cloth from archaeological sites in Paracas-Topará (southern Peru), and her suggestion that these acted as “markers of the sacred,” we examine some ethnographic contexts in highland Bolivia that also concern borders: the final moment of the wayñu dance each year, and the finishing of textile and field borders. In each case, we propose that the object is to control certain spirits believed to dwell within these borders, so that they finish their creative task there. Finally, we examine the relation between the so-called “war of the ayllus” in Bolivia (in 2000), which produced dramatic changes in regional aesthetics, and textile structures postwar, in which images from textile borders came to occupy the central space of woven cloth. We explain these changes through a theory concerning the war dynamics that occur between the borders and centers of modern territories in conflict, and the way that local populations understand these, which might also have archaeological significance in the case of Paracas-Topará.     

Investigation of the composite system of β-lactoglobulin and pectin in aqueous solutions

The compatibility in aqueous systems of β-lactoglobulin (β-lg) with low and high esterified-sodium polypectates (LMP and HMP) was investigated. The mixture did not separate into two co-existing liquid phases in any case studied. At pH above the isoelectric point (IP) of β-lg, the behavior of LMP and HMP was similar when mixing with β-lg. Pectins and β-lg were co-soluble was around a particular ionic strength (μ) (0.07 M for HMP and 0.3 M for LMP). In these circumstances, the flow behavior of pectin was hardly affected by the addition of β-1g . At all other μ, the mixture formed a liquid phase containing both β-lg and pectin and a small amount of β-lg precipitates. Here, the viscosity of the liquid phase was slightly higher than the viscosity of a solution containing the same concentration of pectin. At pH 3.5, i.e. pH⩽IP of β-lg, the behavior of LMP and HMP was different when mixing with β-lg. LMP formed insoluble complexes with β-lg at low μ (⩽0.25 M), but precipitation was suppressed at high μ (0.5 M). The composite system of β-lg/HMP formed a white, homogeneous and stable dispersion at low μ (0.07 M). The viscosity of this dispersion was much higher than the additive viscosity of individual solutions would be. Probably, the oppositely charged β-lg and HMP formed soluble complexes, which further associated into large aggregates. This complexation was also suppressed at high μ (0.5 M).     

Formation of amorphous sugar in the syrup film – a key factor in modelling of industrial sugar drying

A mathematical model of the steady-state sugar drying operation in a cross-flow rotating drum dryer is proposed. Although the model is based on the classic two-film concept of simultaneous heat and mass transfer, it also allows for the formation and growth of a thin layer of amorphous sugar due to local supersaturation of the sugar syrup. The formation of amorphous sugar is a result of the competition between crystallization and drying kinetics. The onset of amorphization is assumed to occur when the system moves from the metastable zone to the labile zone on the sucrose–water phase diagram. The rate of sucrose amorphization is controlled by the conditions prevailing on the metastability limit. Diffusivity of water through the amorphous sugar, the only adjustable parameter of the proposed model, has been determined by fitting sugar moisture data from an industrial Louvre-type dryer. The layer of amorphous sugar plays a critical role during the falling-rate period of drying. Generally, models ignoring its presence tend to overestimate the moisture removal rate. The presented model predicts a dramatic decline of the evaporation rate once the amorphous sugar begins to form which is observed in the industrial practice. The effect of key operating parameters such as air flow rate, hot air temperature, and crystal size on the dryer performance is also discussed.     

Determination of intermediates and mechanism for soot combustion with NOx/O₂ on potassium-supported Mg-Al hydrotalcite mixed oxides by in situ FTIR

The soot combustion with NO(x) and/or O(2) on potassium-supported Mg-Al hydrotalcite mixed oxides under tight contact condition was studied using temperature-programmed oxidation (TPO), isothermal reaction and in situ FTIR techniques. The presence of NO(x) in O(2) favors the soot combustion at lower temperatures (<300 °C). However, a little suppression was observed at higher temperatures (>300 °C), which was accompanied by a substantial NO(x) reduction. The ketene (C═C═O) and isocyanate (NCO(-)) species were determined as the reaction intermediates. In NO(x) + O(2), NO(2) directly interacts with the free carbon sites (C═C*) through two parallel reactions: (1) NO(2) + C═C* → C═C═O + NO; (2) NO(2) + C═C* → NCO(-) + CO(2). The two reactions can proceed easily, which accounts for the promotion effect of NO(x) on soot combustion at lower temperatures. The further oxidation of NCO(-) by NO(2) or O(2) is responsible for the simultaneous reduction of NO(x). However, the reactions between NO(2) and C═C* are limited by the amount of free carbon sites, which can be provided by the oxidation of soot by O(2) at higher temperatures. The interaction of NO(x) and catalyst results in the formation of nitrates and nitrites, which poisoned the active K sites.     

Efficacy of the auto-confusion system for mating disruption of Ephestia kuehniella (Zeller) and Plodia interpunctella (Hübner)

The auto-confusion system for stored-product pyralid moths, based on the contamination of adult males with the sex female pheromone (Z,E)-9,12-tetradecadienyl acetate (commercially known as TDA or ZETA), was evaluated. For this purpose, we applied Exosex SPTab dispensers that contained the Entostat™ powder, at a 5 × 5 m grid, in three facilities, one feed mill in Italy and two retail stores in Greece. In the feed mill, the most abundant pyralid species was Ephestia kuehniella. Monitoring through pheromone-baited traps in this facility indicated that the application of the Exosex SPTab dispensers decreased the number of captures 2 months after the initial application. In the case of the facilities in Greece, the most abundant species was Plodia interpunctella. In these facilities there was a continuous monitoring of moth populations from January 2008 until February 2011, with pheromone-baited traps and Petri dishes with semolina, which served as oviposition traps. In both facilities, the presence of P. interpunctella males in the pheromone-baited traps was reduced after the placement of the Exosex SPTab dispensers, in comparison to captures for the same interval from the previous years. At the same time, the number of emerging individuals in the oviposition traps was notably reduced after the Exosex SPTab dispensers placement, in comparison to the previous monitoring interval. Our study documents that the auto-confusion system is an effective and reliable technique that can be used with success against stored-product Pyralidae, to retail stores and feed mills.     

Light disturbance analysis in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS)

PurposeTo evaluate the perception of light disturbances (LD) in children wearing Dual Focus (DF) MiSight® contact lenses (CLs) for myopia control compared with children wearing single vision spectacles (SV).MethodsThis was a randomized, controlled clinical trial involving subjects aged 8–12 with myopia of -0.75 to -4.00D and astigmatism <1.00D allocated to MiSight^® study CLs group or control group wearing SV. LD was determined at baseline, 12 and 24 months visit with a validated device, Light Disturbance Analyzer (LDA) to determine the shape, size and regularity of the LD phenomena with parameters of Light Disturbance Index (LDI) Best Fit Circle (BFC) and Standard Deviation between LD and BFC (BFC_Irreg.SD).Results74 children completed the study, 41 in the CL group and 33 in the SV group. SV group didn´t show any significant differences between monocular and binocular LD measurements throughout the study. Binocular BFC_Radius was smaller at 24 months visit compared with 12 month visit (p < 0.05) and for BFC_Irreg.SD was significantly smaller at 24 month visit compared with baseline (p < 0.05). In MiSight^® group, binocular and monocular LDI, BFC_Radius and BFC_Irreg.SD measurements didn’t show any significant change between 12 and 24 month visits (p > 0.05). However, monocular BFC_Irreg. as well as monocular and binocular BFC_Irreg.SD showed a significant decrease at 24 month visit compared with 12 month visit.ConclusionsDF lenses increase the monocular light disturbance perception compared with a single vision spectacle correction. However, this effect decreased over the follow-up time and presented a significant binocular attenuation effect.     

Concept of minimum electrospinning voltage (MEV) in electrospinning of PAN–DMF system: effect of distance

Minimum electrospinning voltage (MEV), in a needle–ground plate configuration, is defined as the needle voltage at which the maximum conversion of the polymer dope into nanofibers is achieved in electrospinning. MEV is unique for a set of electrospinning parameters for a given polymer dope and the square of the MEV is directly proportional to the rate of surface formation of the nanofibers in the electrospinning process. In this study, the effect of needle to collector distance on MEV and nanofiber morphology was investigated. The diameter of the nanofibers was found to be primarily dependent on the dope properties and independent of electrospinning process parameters. However, the slope of the plot between (MEV)² and surface formation rate was found to increase with increasing needle to collector distance signifying that the resistance in electrospinning increases linearly with the distance.     

HPLC determination of oxalic acid using tris(1,10-phenanthroline)ruthenium(II) chemiluminescence—application to the analysis of spinach

The chemiluminescence (CL) of Ru(phen)₃²⁺ was applied to HPLC determination of oxalic acid. Oxalic acid was separated by a C₁₈ reverse-phase column with a mobile phase of 0.02 mol/l NH₄Ac. The eluted oxalic acid was mixed with 0.25 mol/l Ru(phen)₃²⁺ and 2.0 mmol/l Ce(SO₄)₂ in 0.08 mol/l H₂SO₄, and then pass through a modified luminometer used as a detector. The reaction of Ce(IV) oxidized Ru(phen)₃²⁺ and oxalic acid emitted light. The detection limit was 6.2×10⁻⁶ mol/l for oxalic acid at a S/N ratio of 3, the relative standard deviation for 5 replicate injections of 1×10⁻³ mol/l oxalic acid standard was calculated as 5.6%, and the linear calibration range was 1×10⁻⁵ to 4×10⁻³ mol/l. The method was successfully applied to determination of oxalic acid in spinach. ©     

Overview of the Development of Chinese Printing Material Industry in 2015(Ⅰ)

正Based on the currently available data,Chinese printing material industry presented a development trend of slow growth in 2015.Paper In the first two years of 12th Five-Year Plan,the average