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Application of natural products as new green agrochemicals with low average lifetime, low concentration doses, and safety is both complex and expensive due to chemical modification required to obtain desirable physicochemical properties. Transport, aqueous solubility, and bioavailability are some of the properties that have been improved using functionalized metal-organic frameworks based on zinc for the encapsulation of bioherbicides (ortho-disulfides). An in situ method has been applied to achieve encapsulation, which, in turn, led to an improvement in water solubility by more than 8 times after 2-hydroxypropyl-beta-cyclodextrin HP-beta-CD surface functionalization. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HR HAADF-STEM) and integrated differential phase contrast (iDPC) imaging techniques were employed to verify the success of the encapsulation procedure and crystallinity of the sample. Inhibition studies on principal weeds that infect rice, corn, and potato crops gave results that exceed those obtained with the commercial herbicide Logran. This finding, along with a short synthesis period, i.e., 2 h at 25 degrees C, make the product an example of a new generation of natural-product-based herbicides with direct applications in agriculture., This work was financially supported by the "Ministerio de Economia y Competitividad" (Project AGL2017-88083-R), Spain. Furthermore, this work has received financial support from Junta de Andalucia (FQM334), MINECO/FEDER (Projects MAT2017-87579-R). This project has received funding from the European Union's Horizon 2020 research and innovation program under Grant 823717-ESTEEM3. STEM studies were performed at the DME Facilities of SCCYT of the University of Cadiz

Since silver nanowires (AgNWs) show high infrared reflectance many studies present their applicability as thermal management products for various wearable textiles. However, their use for practical purposes is only partially evaluated, without focusing on improving their low atmospheric and liquid stability. This report describes a new approach for the topic and proposes a facile method of Ag nanowire passivation with a SnO2 layer for high environmental stability and retention of high infrared reflectance. The one-step passivation process of AgNWs was carried out in the presence of sodium stannate in an aqueous solution at 100 degrees C, and resulted in the formation of core/shell Ag/SnO2 nanowires. This study presents the morphological, chemical, and structural properties of Ag/SnO(2)NWs formed with a 14 nm thick SnO2 shell, consisting of 7 nm rutile-type crystals, covering the silver metallic core. The optical properties of the AgNWs changed significantly after shell formation, and the longitudinal and transverse modes in the surface plasmon resonance spectrum were red shifted as a result of the surrounding media dielectric constant changes. The passivation process protected the AgNWs from decomposition in air for over 4 months, and from dissolution in a KCN solution at concentrations up to 0.1 wt%. Moreover, the report shows the microwave irradiation effect on the shell synthesis and previously synthesised Ag/SnO(2)NWs. The post-synthesis irradiation, as well as the SnO2 shell obtained by microwave assistance, did not allow long-term stability to be achieved. The microwave-assisted synthesis process was also not fast enough to inhibit the formation of prismatic silver structures from the nanowires. The Ag/SnO(2)NWs with a shell obtained by a simple hydrolysis process, apart from showing high infra-red reflectance on the para-aramid fabric, are highly environmentally stable. The presented SnO2 shell preparation method can protect the AgNW's surface from dissolution or decomposition and facilitate the designing of durable smart wearable thermal materials for various conditions.

The beneficial effects of fish consumption in both children and adults are well known. However, the intake of methylmercury, mainly from contaminated fish and shellfish, can have adverse health effects. The study group on the prevention of exposure to methylmercury (GEPREM-Hg), made up of representatives from different Spanish scientific societies, has prepared a consensus document in a question and answer format, containing the group's main conclusions, recommendations and proposals. The objective of the document is to provide broader knowledge of factors associated with methylmercury exposure, its possible effects on health amongst the Spanish population, methods of analysis, interpretation of the results and economic costs, and to then set recommendations for fish and shellfish consumption. The group sees the merit of all initiatives aimed at reducing or prohibiting the use of mercury as well as the need to be aware of the results of contaminant analyses performed on fish and shellfish marketed in Spain. In addition, the group believes that biomonitoring systems should be set up in order to follow the evolution of methylmercury exposure in children and adults and perform studies designed to learn more about the possible health effects of concentrations found in the Spanish population, taking into account the lifestyle, eating patterns and the Mediterranean diet.

Carbon integral honeycomb monoliths with good performance in the thermocatalytic decomposition of methane were deeply characterized to understand the differences of behaviour resulting from their different pre-treatment. In particular three types of carbon monoliths were investigated, just carbonized, and activated with and without pre-oxidation. Advanced techniques such as X-ray Diffraction with Rietveld analysis, X-ray Photoelectron Spectroscopy and Scanning-Transmission Electron Microscopy with HAADF and EELS analysis were applied to unveil the origin of their differences which could not be correlated with the textural properties nor with the surface groups functionality. Particular attention was paid to the initial defects concentration and the nature of the carbon produced during the reaction, not finding either clear differences between the three types of monoliths studied. On the contrary the simply activated monoliths, with the highest activity, seemed to have higher content of a relatively amorphous graphite in which more actives sites for the reaction must be present. They also exhibited higher initial percentage of carbon atoms on the surface and a relative increase of C–C bonds after reaction. In addition the interaction between the carbonaceous phase and some of the phases of the clay used to extrude the starting coal could influence the carbon reactivity.

The aim of the present work is to explore the combination of atomic force electrochemical microscopy, operated in molecule touching mode (Mt/AFM-SECM), and of dense nanodot arrays, for designing an electrochemically addressable molecular nanoarray platform. A high density nanoarray of single grained gold nanodots (∼15 nm-diameter nanoparticles, 100 nm pitch) is decorated by a model molecular system, consisting of ferrocene (Fc) labeled polyethylene glycol (PEG) disulfide chains. We show that the high resolution of Mt/AFM-SECM enables the electrochemical interrogation of several hundreds of individual nanodots in a single image acquisition. As a result, the statistical dispersion of the nanodot molecular occupancy by Fc-PEG chains can be reliably quantified, evidencing that as little as a few tens of copies of redox-labeled macromolecules immobilized on individual nanodots can be detected. The electrochemical reactivity of individual nanodots can also be reliably sampled over a large population of nanodots. We evidence that the heterogeneous rate constant characterizing the electron transfer between the nanodots and the Fc heads displays some quantifiable variability but that the electron transfer remains in any case in the quasi-reversible regime. Overall, we demonstrate that Mt/AFM-SECM enables high throughput reading of dense nanoarrays, with a sensitivity and a read-out speed considerably higher than previously reported for scanning electrochemical microscopy (SECM) imaging of molecular microarrays.

The {\pi}-{\pi} interactions between organic molecules are among the most important parameters for optimizing the transport and optical properties of organic transistors, light-emitting diodes, and (bio-) molecular devices. Despite substantial theoretical progress, direct experimental measurement of the {\pi}-{\pi} electronic coupling energy parameter t has remained an old challenge due to molecular structural variability and the large number of parameters that affect the charge transport. Here, we propose a study of {\pi}-{\pi} interactions from electrochemical and current measurements on a large array of ferrocene-thiolated gold nanocrystals. We confirm the theoretical prediction that t can be assessed from a statistical analysis of current histograms. The extracted value of t ca. 35 meV is in the expected range based on our density functional theory analysis. Furthermore, the t distribution is not necessarily Gaussian and could be used as an ultrasensitive technique to assess intermolecular distance fluctuation at the subangstr\"om level. The present work establishes a direct bridge between quantum chemistry, electrochemistry, organic electronics, and mesoscopic physics, all of which were used to discuss results and perspectives in a quantitative manner., Comment: Nano Lett (2017), full text and supporting information

Several studies have shown an inverse relationship between selenium status and cardiovascular health, although epidemiologic evidence yielded by the randomized trials did not find a beneficial effect of selenium administration. The aim of this study was to analyze the association between serum selenium levels and lipid profile adjusted by age, sex and other associated factors among a general adult population in Spain.We recruited 372 hospital employee volunteers (60 men and 312 women) with a mean age of 47 (SD: 10.9), whom were given a standardized questionnaire. Serum selenium concentration was measured by electrothermal atomization atomic absorption spectrometry. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry.The mean of serum selenium was 79.5μg/L (SD: 11.7) with no sex-dependent differences. In the multivariate linear regression analysis, the associated factors with the mean levels of selenium were: age (β=0.223; CI 95%: 0.101-0.345), p0.001; widowhood (β=-9.668; CI 95%: -17.234 to -2.102), p=0.012; calcium supplements (β=3.949; CI 95%: 0.059-7.838), p=0.047; zinc (β=0.126; CI 95%: 0.013-0.238), p=0.028 and glucose (β=0.172; CI 95%: 0.062- 0.281), p=0.002; Participants with serum selenium≥79.5μg/L were 1.98 (OR=1.98; CI 95% 1.17-3.35; p=0.011) and 2.04 times (OR=2.04; CI 95% 1.06-3.97; p=0.034) more likely to have cholesterol ≥200mg/dL and LDL-c ≥100mg/dL respectively than those with serum selenium79.5μg/L.Higher selenium was positively associated with increased total and LDL cholesterol but not with HDL-c and triglycerides. More studies are needed in order to confirm the lower serum selenium findings in widows.

C3) are heated to 1000–1100 °C for 2–4 hr in an argon flow. Carbon nanotubes are formed when metal powders, e.g. Fe, Co, Y and Ni, are also present.

International audience; Using a method that combines experimental and simulated Aberration-Corrected High Resolution Electron Microscopy images with digital image processing and structure modeling, strain distribution maps within gold nanoparticles relevant to real powder type catalysts, i.e., smaller than 3 nm, and supported on a ceria-based mixed oxide have been determined. The influence of the reduction state of the support and particle size has been examined. In this respect, it has been proven that reduction even at low temperatures induces a much larger Compressive strain on the first 111 planes at the; interface. This increase in compression fully explains, in accordance with previous DFT calculations, the loss of CO adsorption capacity of the interface area previously reported for Au supported on ceria-based oxides.

A variety of advanced (scanning) transmission electron microscopy experiments, carried out in aberration-corrected equipment, provide direct evidence about subtle structural changes taking place at nanometer-sized Au||ceria oxide interfaces, which agrees with the occurrence of charge transfer effects between the reduced support and supported gold nanoparticles suggested by macroscopic techniques. Tighter binding of the gold nanoparticles onto the ceria oxide support when this is reduced is revealed by the structural analysis. This structural modification is accompanied by parallel deactivation of the CO chemisorption capacity of the gold nanoparticles, which is interpreted in exact quantitative terms as due to deactivation of the gold atoms at the perimeter of the Au||cerium oxide interface.

The general population is increasingly exposed to cerium (Ce), which is contained in industrial products or is present as nuclear Ce fission products. Some studies suggested a link between elevated Ce levels and endomyocardial fibrosis. Since breast milk is the optimal, and directly after birth, usually the sole nutrition for newborns, exposure of females to Ce and its transfer to infants by breast-feeding is of concern in neonate protection. Consequently, the transfer rate of Ce from blood to breast milk is of interest for elucidating the Ce exposure of infants. Biomonitoring of paired serum and breast milk samples provides such information about Ce transfer to human milk. Therefore, this study is aimed at clarification of the relationship between Ce in human milk and serum from respective mothers for elucidating Ce enrichment in human milk with possible nutritional risk for newborns. As a prerequisite a strictly quality-controlled Ce determination method applicable to very low Ce concentration was developed, and its figures of merit were determined and found to be sufficient for our purpose. It turned out that Ce concentration in milk from Munich (Germany) and Madrid (Spain) showed a median of 13 ng/L. Ce concentrations in serum were at limit of quantification (LOQ) 10 ng/L (Munich) or 21.6–70.3 ng/L (Madrid), suggesting a higher Ce intake in Madrid. No enrichment from blood to milk was seen, and no elevated nutritional risk for breast-fed babies from Ce was found. Ce in serum, but not in milk, could indicate environmental Ce.

The challenging problem of mapping the chemical composition of cation columns in individual nanocrystals at atomic resolution is addressed by using a method based on aberration-corrected electron microscopy, core-loss electron energyloss spectroscopy, and simulations. The potential of this novel approach to provide unique structural information, which is the key to rationalizing macroscopic behavior, is illustrated with the analysis of ceria–zirconia mixed oxides, which are nanomaterials with substantial technological impact. Metal nanoparticles supported on this family of oxides are currently materials of interest as catalysts in a variety of chemical transformations in the area of environmental protection, such as low-temperature water-gas shift, selective oxidation of CO in the presence of large amounts of hydrogen, or three-way catalysis. Strong variations in the chemistry of ceria–zirconia mixed oxide catalysts have been observed after they have undergone redox cycles involving reduction treatments at high temperatures ( 1173 K) then oxidation at mild temperatures ( 823 K). In particular their reducibility is significantly enhanced after such aging treatments. Scanning transmission electron microscopy (STEM) techniques have provided crucial information to account for these changes in the redox behavior. High-resolution electron microscopy (HREM) combined with high-angle annular dark-field (HAADF) imaging and tomography have revealed the occurrence of a disorder–order transformation in the cationic sublattice of these oxides, which tend to rearrange into a distribution characteristic of the so called pyrochlore phase. This phase is an archetype structure for A2B2O7 (A= + 3 cation, B=+ 4 cation) compounds and can be considered a fluorite superstructure. The structural transformation takes place during the reduction step of the cycle, in which the fully reduced mixed oxide with Ce/Zr molar ratio 1:1 adopts the Ce2Zr2O7 stoichiometry. Nevertheless, HAADF studies have clearly shown that, in the case of ceria–zirconia mixed oxides, this cation-ordered arrangement is preserved even after full reoxidation, that is, in the oxide with Ce2Zr2O8 stoichiometry, whenever the oxidation temperature does not exceed 823 K. Electron-microscopy studies have also revealed another remarkable feature of the ceria–zirconia aged oxides with the pyrochlore-type cation sublattice: the occurrence of compositional heterogeneities at the nanometer scale. Taking these observations into account and also considering that the disorder–order transition may not be completed in the time scale and under the temperature conditions used in the redox-cycling treatments, the important question arises whether these heterogeneities are in fact occurring on a finer scale, that is, at the atomic level. Such heterogeneities, compatible with the HREM and HAADF observations, will strongly influence the details of the counterpart oxygen sublattice and, consequently, the chemical and catalytic response of these oxides. To date, the atomic-column by atomic-column compositional analysis of the oxidized pyrochlore required to justify such a possibility has not been accomplished. Herein, using the capabilities of an aberration-corrected Nion UltraSTEM microscope (operated at 100 kV) we not only provide the first direct chemical evidence of the cationic order present in the Ce2Zr2O8 oxidized pyrochlore but we also show how atomicresolution electron energy-loss spectroscopy (EELS) mapping, based on core–shell ionization, can be combined with EELS image simulation to detect quite subtle local deviations in the cation sublattice from the completely ordered structure. This information provides a much more accurate structural description of the active catalyst nanocrystals, which must be considered to model both their oxygen-exchange capabilities and, eventually, their catalytic performance. [*] Dr. S. Trasobares, Dr. M. L pez-Haro, Dr. J. A. Perez-Omil, Dr. J. J. Calvino Departamento de Ciencia de los Materiales e Ingenier a Metalfflrgica y Qu mica Inorg nica Facultad de Ciencias, Universidad de C diz Campus Rio San Pedro, 11510-Puerto Real, C diz (Spain) Fax: (+34)956-016286 E-mail: susana.trasobares@uca.es Homepage: http://www.uca.es/tem-uca

Trace elements may play an important role in bipolar disorders. The objective of this study is to determine serum copper and zinc, blood lead and cadmium and urine lead, cadmium and thallium concentrations in patients diagnosed with bipolar disorders and to compare these levels with those of a healthy control group.A total of 25 patients diagnosed with bipolar disorder and 29 healthy subjects participated in this study. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry; the blood lead and cadmium concentrations were measured by electrothermal atomization atomic absorption spectrometry with Zeeman background correction; urine lead, cadmium and thallium concentrations were measured by inductively coupled plasma mass spectrometry.Median blood and urine lead and cadmium levels were significantly higher among the bipolar patients than among the control group: Blood lead (μg/dL): patient median: 3.00 (IQR: 1.40-4.20); control median (μg/dL): 2.20 (IQR: 0.90-3.00) p=0.040. Blood cadmium (μg/L): patient median: 0.39 (IQR: 0.10-1.15); control median: 0.10 (IQR: 0.10-0.17) p0.001. The median of cadmium (μg/L) in patients who smoked (1.20 IQR: 0.44-2.30) was higher than that in non-smokers (0.12 IQR: 0.10-0.34) p0.001. There was a statistically significant increase (p=0.001) in zinc levels among patients in the manic phase (mean 111.28, SD: 33.36 μg/dL) with respect to the control group (mean 86.07, SD: 12.39 μg/dL).The results suggest that there could be higher levels of some toxic trace elements in the group of patients with bipolar disorder than in the healthy control group.

The influence of the highly dispersed gold phase on the CO-support interaction occurring in two 2.5 wt % Au/Ce(0.62)Zr(0.38)O(2) catalysts with medium (Au/CZ-MD) and high (Au/CZ-HD) metal dispersion is quantitatively assessed. For this purpose, we have followed an approach in which high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), computer modelling, volumetric adsorption and FTIR spectroscopy studies are combined. This approach has already been fruitfully applied to the investigation of the specific CO-metal adsorption in Au/ceria-zirconia catalysts. As deduced from the experimental studies reported herein, the presence of gold dramatically increases the amount of CO strongly chemisorbed on the support. Moreover, this amount is sensitive to the metal dispersion, thus suggesting the occurrence of a mechanism in which the CO molecules that are initially adsorbed on the gold nanoparticles are further transferred to the support by means of a spillover process. An annular model is proposed for the growth of the CO phase adsorbed on the ceria-zirconia mixed oxide in the presence of Au. By assuming this model, we have estimated the width of the annulus, Delta r, of the adsorbed CO grown around the Au nanoparticles in Au/CZ-MD and Au/CZ-HD catalysts. This value is found to be very close to Delta r approximately 2 nm in both cases, the coincidence lending some additional support to the model. To further confirm this proposal, we have investigated the influence of CO pre-adsorption on the D(2)-Au/CZ-MD interaction, at 298 K. As revealed by FTIR spectroscopy, the kinetics of the deuterium spillover is significantly disturbed by the pre-adsorbed CO, which is fully consistent with an annular model for the CO adsorption. We conclude from the global analysis of the results reported here and those already available on CO-Au adsorption that the appropriate combination of nanostructural, computer modelling and chemical techniques is a powerful tool allowing us to gain a comprehensive picture of the complex series of processes involved in the CO adsorption on this relevant family of gold catalysts.

Bimetallic CoNi nanoparticles have been prepared within the apoferritin cavity. The protein shell controls size, prevents aggregation, and makes nanoparticles water-soluble. The CoNi series prepared in this way were structurally and magnetically characterized, the resulting magnetic properties varying accordingly with composition (Co(75)/Ni(25), Co(50)/Ni(50), Co(25)/Ni(75)). Co and Ni metals were associated in each nanoparticle, as demonstrated by high-angle annular dark field scanning electron microscopy and electron energy loss spectroscopy (EELS). After intentional oxidation, the CoNi nanoparticles were characterized by EELS, X-ray absorption near edge structure (XANES), and SQUID measurements to evaluate the importance of the oxidation on magnetic properties.

The present work deals with the synthesis of carbon nanotube-zeolite composites using as method the catalytic liquid spray pyrolysis. The nanotubes were formed after pyrolysis of toluene on the surface of a zeolite of type ZSM-5, which was used as a catalytic substrate. ZSM-5 zeolite was synthesized using the autoclave process and full characterized. Prior to the pyrolyses, the catalytic substrates were produced by mixing a certain amount of zeolite with a solution of Fe(NO3)3•9H2O of specific concentration. The obtained materials from the spray pyrolysis were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetry-differential analysis (TG-DTA).

An in-depth structural and analytical investigation of two 25 wt % Ce0.8Pr0.2O2/d-Al2O3 catalysts, d = 3.5 wt % SiO2, 4 wt % La2O3, is performed aimed at clarifying the origin of the differences in the evolution of their oxygen storage capacity with temperature. Using a combination of transmission and scanning transmission electron microscopy techniques, the fine details of the structural and compositional changes of the two catalysts with reduction temperature has allowed us to establish the role of SiO2 as a stabilizer of the oxygen handling properties of the Ce−Pr mixed oxide phase under high temperature reducing environments. The entire set of data clearly reveals that Pr does not fully mix with Ce during the synthesis of both catalysts, the spatial distribution of this uncombined fraction of Pr loading being in each case very different: as nanosized particles in the catalyst prepared on the SiO2-doped substrate and as a highly dispersed phase in the lanthana modified alumina catalyst. Therefore, SiO2...

After being heated in a flow of 5% O2/He, at 1073 or 1123 K for 30 min, a Ce0.62Zr0.38O2 sample showing an ordered cationic sublattice had very subtle surface nanostructural changes induced on it. In parallel with them, a significant loss of low-temperature (T ≤ 773 K) oxygen storage capacity (OSC), with no modification of its high-temperature (T ≥ 973 K) redox response, was observed. These nanostructural and chemical features characterize the very first stage of the process leading to the destruction of the ordered Ce−Zr sublattice, a structural phenomenon playing a key role in the control of redox behavior of ceria−zirconia mixed oxides. The reported results, including OSC, hydrogen chemisorption, and nanostructural and nanoanalytical data, lend further support to a model providing a comprehensive interpretation of the complex relationship linking thermal aging conditions, nanostructural properties, surface chemistry, and redox behavior in these materials.

By using a combination of transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) techniques, we have followed in detail the structural and chemical changes occurring on the very surface layers of powder CexPr1-xO2 mixed oxides, used as supports, during the preparation of rhodium-supported catalyst by wet impregnation techniques. Results demonstrate the occurrence of Pr3+ leaching out of the Ce−Pr solid solution during the impregnation step, which promotes a severe spatial redistribution of lanthanide cations at the surface of the mixed oxide. A highly heterogeneous surface composition is reached after the metal deposition. Mobilization of the support also affects the features of the final surface structure of the metal-supported nanoparticles, which become decorated by patches of support material. All these facts seem crucial to properly understand the redox and catalytic behavior of this kind of materials.

The evolution of the ceria-praseodymia mixed oxide promoter throughout the successive steps involved in the preparation of a 3% Rh/25% Ce 0.8 Pr 0.2 O 2-x /Al 2 O 3 - 3.5% SiO 2 catalyst is studied with the help of X-ray diffraction (XRD), spatially resolved electron energy loss spectroscopy (EELS), XPS, and thermal programed desorption (TPD) techniques. Incipient wetness impregnation has been used to obtain the appropriate loading of this promoter. As revealed by XRD, EELS, and XPS data, the alumina-supported CeO 2 -PrO 2-x mixed oxide sample consisted of a bimodal distribution of the particles of the promoter. XRD shows two fluorite-like phases: cerium-rich particles with a mean crystallite size greater than 6 nm and smaller praseodymium-rich crystals, about 3.5 nm size. Surface Ce/Pr ratio obtained by XPS was consistent with a higher dispersion of the praseodymium-rich oxide particles. The final Rh catalyst was prepared in a second step, by impregnation of the CePrO x /Al 2 O 3 system with an acidic solution of Rh(NO 3 ) 3 . The low pH of this solution is responsible for further modifications of the lanthanide oxides distribution. Thus, there is a redispersion of the praseodymium-rich phase, which is evidenced by EELS and XPS data. Likewise, CO 2 desorption from samples exposed to the atmosphere is consistent with an enhanced basicity of the sample due to the increase of Pr 3+ content at the surface of the catalyst. The observed changes on the nanostructure of the mixed oxide promoter can be attributable to a partial dissolution of the oxide, selectively leaching Pr 3+ cations from the lattice, which are finally deposited as small particles after the drying steps of the preparation.

The addition of iron to high-area TiO2 (Degussa P25, a mixture of anatase and rutile) increases the number of oxygen defect sites that react with O2 to form peroxide and superoxide species. In the presence of gold nanoclusters on the TiO2 surface, the superoxide species become highly reactive, and the activity of the supported gold catalyst for CO oxidation is approximately twice that of the most active comparable catalysts described in the literature. Images of the catalyst obtained by scanning transmission electron microscopy combined with spectra of the catalyst measured in the working state (Raman, extended X-ray absorption fine structure, and X-ray absorption near-edge structure) indicate strong interactions of gold with the support and the presence of iron near the interfaces between the gold clusters and the TiO2 support. The high activity of the catalysts is attributed to the presence of defects in these sites that activate oxygen.

High-resolution electron microscopy, high-angle annular dark field images, electron tomography data, and density functional theory calculations are presented that show the occurrence of significant structural and surface modifications in a nanocrystalline sample of cerium−zirconium mixed oxide upon high-temperature reduction with hydrogen followed by mild oxidation. Our findings may lend further support to a recently proposed model in accordance with which the enhanced reducibility exhibited by the mixed oxide after this treatment is due to parallel modifications occurred in its surface chemistry.

International audience; A novel CeO2/MgO catalyst with low ceria loading has been synthesized. This catalyst showed unique redox properties compared with conventional high and low surface area CeO2. Advanced (scanning) transmission electron microscopy techniques revealed the presence of a variety of highly dispersed ceria nanostructures: isolated CeOx entities, CeO2 clusters, as well as fairly small (

The decomposition process of melamine exposed to a high-energy electron beam has been investigated by monitoring the changes in the energy loss near edge structures (ELNES) using time-resolved elec...

CNx thin films have been prepared by ion beam assisted deposition (IBAD) varying the C-atom to N-ion ratio during deposition. The layers were studied by means of TEM and EELS investigation, ERDA and AES depth profiling. The obtained films were amorphous. The incorporation probability of N into the films was found to depend on the N/C arrival ratio. Large amount of N incorporation was found above and small amount below a N/C arrival rate of 0.3. Due to intentional change in the N/C arrival rate, modulated structures have been produced. The N concentration in the individual layers of modulated samples was found to exhibit distinct values of approximately 5 and 20 at.%. The erosion rate of the various CNx layers upon Ar+-ion bombardment depends on their N content. The relative erosion rate of the samples containing nitrogen of 20 and of 5 at.% was found to be rrel=r20%/r5%=1.6 (1.2 keV, 83° angle of incidence. It was determined by XTEM and EELS that the origin of the TEM image contrast marking out the individual sublayers is mainly due to density variations in the modulated structure and partly due to thickness differences of the cross sectional TEM samples as a result of Ar+ ion milling of layers of various compositions.

A systematic study of the effect of different synthesis parameters on N incorporation into C nanotubes is presented. CNx nanotubes prepared by catalyzed pyrolysis of melamine exhibit a highly compartmentalized morphology with a remarkable periodicity structure along the nanotube axis. Spatially resolved electron energy loss spectroscopy (spectrum-imaging mode) indicates that the nanotubes are made of carbon and nitrogen, inhomogeneously distributed with an enrichment of carbon on the external surfaces. The evolution of the C-K-edge shape across the nanotube reveals a transition from a graphitic stacking on the outside to a disorganized-mixed type in the core of the nanotube. For the N-K edge, the situation is more complex. The fine structure of the N-K edge differs depending on the used catalyst, which indicates differences in the bonding configuration. When Ni is used as a catalyst, N replaces C in the graphitic structure whereas C–N pyridinic-like bonds are formed when the catalyst is Fe. The compartmen...

Nanocrystals of a new CN phase of presumably orthorhombic type embedded in an amorphous CN x (x matrix produced by magnetron sputtering have been identified. The evidence for the co-existence of different phases in the sample is first given by spatially resolved electron energy loss spectroscopy (EELS). A mathematical treatment of collections of EELS spectra applied to the core-edge fine structures (energy loss near edge fine structures (ELNES)) was used to isolate the characteristic signature of the different phases. Electron diffraction patterns and high-resolution transmission electron microscopy images (HRTEM) were then carried out from areas displaying the characteristic identified ELNES to confirm the identification of the structure and chemistry of these nanocrystals.

In relation with the applications of CeO2-ZrO2 mixed oxides in catalysis, new synthetic routes aim at preparing materials with improved performances in terms of durability and high temperature textural and chemical resistance [1]. Barium-doped alumina (BDA) as well as Barium hexaaluminates (BHA), BaO·6Al2O3, present high thermal stability, this making them suitable supports of highly dispersed catalytic active phases, e.g. in combustion processes [2]. Thus, these materials seem appropriate to prepare supported CeO2-ZrO2 catalysts with improved high temperature stability.

A pretreated petroleum residue was hydroprocessed in a continuous hydroprocessing unit provided with a continuous stirred tank reactor. In this paper, the kinetic study of Conradson carbon residue (CCR) conversion is reported. The range of CCR conversion is 5.6−62.4%. The data of CCR conversion fit first-order kinetics, and the activation energy is 36.3 kcal/mol. No pressure dependence of the rate constants as defined by the equation K = K * was observed. The structural analysis of the feed and products indicated that hydroprocessing produces an increase in the saturated fraction and a decrease in the polar fraction. The higher content of saturated fraction in the products obtained at 400 °C than in those obtained at 415 °C together with the increase in aromatic carbon and decrease in molecular weight in the products processed at 415 °C seem to indicate that cyclization reactions plus aromatization of the formed rings are being produced at this temperature. The asphaltene content was linearly related with the CCR content, and the gas yield and 525+ °C fraction conversion were linearly related with the CCR conversion., We thank the European Community (Contract JOU2-CT92-0206) and the DGICYT (AMB93-1137-CE) for financial support.

An asphaltenic residue from deasphalting a synthetic crude obtained by direct liquefaction of a subbituminous Spanish coal was submitted to several upgrading routes. In this paper, the kinetics of sulfur-removal reactions in thermal, hydrothermal, and hydrocatalytic cracking are reported. The sulfur-removal reactions fit a 2.7 kinetic order for the thermal process, a 3.8 kinetic order for the hydrothermal process, and a 4.7 kinetic order for the hydrocatalytic process, the activation energy being lowest in the hydrocatalytic process. The activation energy for the thermal processes is higher in the presence of hydrogen. The percentages of sulfur removal range from 3.6 to 56.6 wt % in thermal cracking, from 15.3 to 61.5 wt % in hydrothermal cracking, and from 19.1 to 55.0 wt % in hydrocatalytic cracking. The percentages of sulfur removal at low reaction times for the three processes increase in the order thermal < hydrothermal < hydrocatalytic., This work was sponsored by UE Contract No. EN3V-0055E and the Spanish DGICYT Project CE89-0007.

Nano-structural and nano-analytical studies show that the dramatic difference in CO oxidation activity observed between two Au/Ce0.50Tb0.12Zr0.38O2−x samples prepared by deposition–precipitation with urea and further activated under oxidising or reducing conditions is due to the poisoning effect of a very thin layer of carbon grown on the pre-reduced catalyst.

Nanoscale resolution electron microscopy analysis combined with ion beam assisted techniques are presented here, to give answers to full characterization of morphology, growth mode, phase formation, and compositional distribution in nanocomposite TiAlSiN coatings deposited under different energetic conditions. Samples were prepared by magnetron sputtering, and the effects of substrate temperature and bias were investigated. The nanocomposite microstructure was demonstrated by the formation of a face-centered cubic (Ti,Al)N phase, obtained by substitution of Al in the cubic titanium nitride (c-TiN) phase, and an amorphous matrix at the column boundary regions mainly composed of Si, N (and O for the samples with higher oxygen contents). Oxygen impurities, predicted as the principal responsible for the degradation of properties, were identified, particularly in nonbiased samples and confirmed to occupy preferentially nitrogen positions at the column boundaries, being mainly associated to silicon forming oxynitride phases. It has been found that the columnar growth mode is not the most adequate to improve mechanical properties. Only the combination of moderate bias and additional substrate heating was able to reduce the oxygen content and eliminate the columnar microstructure leading to the nanocomposite structure with higher hardness (>30 GPa). ©2012 Microscopy Society of America ., The authors are thankful for financial support from the EC (project NoE EXCELL and REGPOT AL-NANOFUNC), Spanish Ministry MICINN (CONSOLIDER FUNCOAT), CSIC (20160I041 and 201060E102), and Junta de Andalucía(TEP 217).

Introduction Exposure to lead and cadmium is a public health problem due to the broad exposure to these toxic substances among the general population. The objective of this study is to determine blood lead and cadmium concentrations in a working population drawn from six university hospitals in Madrid, Getafe, Cartagena, Santiago de Compostela, Santander and Palma de Mallorca (Spain) and to identify associated factors. Materials and methods 951 individuals participated in the study and were administered the standardized PESA ® questionnaire regarding exposure to lead and cadmium. The blood lead and cadmium concentrations were measured by electrothermal atomization atomic absorption spectrometry with Zeeman background correction in Perkin-Elmer spectrometers, guaranteeing the transferability of the results. Results The median overall blood lead concentration was: 1.6 μg/dL (IQR: 0.9–2.7) and that of cadmium was: 0.21 μg/L (IQR: 0.10–0.50). There were significant differences in lead levels between men (2 μg/dL) and women (1.5 μg/dL), postmenopausal (2.6 μg/dL) and premenopausal women (1.1 μg/dL), and between participants who cooked in earthenware (2.1 μg/dL) and those who did not (1.5 μg/dL). The median of cadmium in women (0.24 μg/L) was higher than in men (0.11 μg/L) and was also higher in subjects who smoked (0.70 μg/L) than in non-smokers (0.13 μg/L). Conclusions A reduction in blood lead and cadmium levels was observed with respect to previous studies carried out in Spain. Nevertheless, the results suggest there are certain factors which increase risk such as age, gender, menopause, age of housing, cooking in lead-glazed earthenware and exposure to cigarette smoke.

The aim of this study was to evaluate the relationship between cerium content in human breast milk and blood plasma or serum. Blood samples and breast milk at various stages of lactation, from 5 days to 51 weeks post partum, were donated by 42 healthy breast-feeding mothers from Munich, Germany and by 26 lactating Spanish mothers from Madrid at 4 weeks post partum. Inductively coupled plasma mass spectrometry was applied for the determination of cerium in the biological samples. Cerium concentration in the digested milk samples from Munich showed low values and the arithmetic mean values ranged between the quantification limit of 5 ng/L up to 65 ng/L. The median value amounted to 13 ng/L. The cerium concentrations in the Spanish breast milk samples amounted to similar low values. The data were about a factor of eight lower than values found in a former study of samples from an eastern German province. All cerium concentrations in the German plasma samples, except for two, were at the quantification limit of 10 ng/L. Interestingly, the serum samples of the Spanish mothers showed cerium values ranging between 21.6 and 70.3 ng/L; these higher data could be explained by an enhanced intake of cerium by humans in Madrid. This could be caused by increased cerium concentrations in particulate matter due to a higher traffic volume in Madrid compared to Munich. The results obtained in this study contribute to setting reference baseline values of cerium in human breast milk and blood plasma/serum and indicate a varying cerium amount depending on the cerium environmental pollution. Possibly, the cerium content in plasma/serum could be an indicator for environmental cerium, which is not valid for breast milk.

We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbon nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.

CePrOx mixed oxides, which present extraordinary redox properties, have a wide range of potential applications in environmental catalysis [1]. A good dispersion of these oxides over a high surface area material, like alumina, increases their specific surface and, hence, their oxygen handling capabilities. Moreover if the alumina support is modified with a doping agent, their textural stability can be improved and their deactivation by solid-state reaction with the support inhibited [2]. In this work, Transmission Electron Microscopy Imaging Techniques (HREM and HAADF) have been combined with spectroscopic techniques, (EELS and X-EDS), to investigate the influence of the dopant nature (SiO2, La2O3) on the chemical and structural properties of CePrOx particles supported on modified aluminas.. A mechanism to explain the differences observed [3] in the resistance against high temperature deactivation of a Ce0.8Pr0.2O2−x supported on Si-doped alumina (Ce0.8Pr0.2O2−x/Al2O3− 3.5% SiO2) and a La-doped alumina (Ce0.8Pr0.2O2−y/Al2O3−4% La2O3) system is proposed. To reveal the effects of high temperature aging, samples of the two catalysts were studied after treatments under reducing conditions at low, 350°C, and high temperature, 900°C.

Noble metals highly dispersed on cerium mixed oxide supports Ce(M)O2−x (M=Zr,Tb) are currently being investigated, not only due to their relationship with the so called Three-Ways Catalysts (TWC) but also because of their potential applications in other catalytic processes related to the hydrogen production or the elimination of organic pollutants in residual waters from different industrial processes [1]. Among these supported noble metals catalysts, Ru containing materials seems to be more stable while at the same time very active and selective in comparison with other supported noble metals [2].

Transmission Electron Microscopy (TEM), X-ray Absorption Near Edge Spectroscopy (XANES), Electron Energy-Loss Spectroscopy (EELS), Small-Angle X-ray Scattering (SAXS), and SQUID magnetic studies were performed in a batch of horse spleen ferritins from which iron had been gradually removed, yielding samples containing 2200, 1200, 500, and 200 iron atoms. Taken together, findings obtained demonstrate that the ferritin iron core consists of a polyphasic structure (ferrihydrite, magnetite, hematite) and that the proportion of phases is modified by iron removal. Thus, the relative amount of magnetite in ferritin containing 2200 to 200 iron atoms rose steadily from approximately 20% to approximately 70% whereas the percentage of ferrihydrite fell from approximately 60% to approximately 20%. These results indicate a ferrihydrite-magnetite core-shell structure. It was also found that the magnetite in the ferritin iron core is not a source of free toxic ferrous iron, as previously believed. Therefore, the presence of magnetite in the ferritin cores of patients with Alzheimer's disease is not a cause of their increased brain iron(II) concentration.

This work reports on the hydrogen interaction with a 3 wt % Au/Ce0.62Zr0.38O2 (Au/CZ) catalyst prepared by deposition−precipitation. As deduced from X-ray powder diffraction, electron microscopy (scanning transmission electron microscopy−high-angle angular dark field and high-resolution electron microscopy), and CO volumetric/Fourier transform IR (FTIR) adsorption studies, the investigated catalyst shows a good metal dispersion. By combining FTIR spectroscopy and volumetric chemisorption studies, it is shown that upon treating the Au/CZ catalyst with 40 Torr of H2 at room temperature a fast and very intense spillover effect occurs. As determined from the recorded isotherm, very high values of the apparent H/Au ratio (>8.0) and of the atomic hydrogen surface density (>11.0 H/nm2) are reached. In parallel with this observation, the onset of a characteristic IR band at 2133 cm-1 shows the occurrence of significant support reduction with inherent appearance of Ce3+ species. Moreover, the simultaneous growth of the IR band at 1630 cm-1 due to molecular water strongly suggests that even at room temperature oxygen vacancies are also formed. Additional FTIR spectroscopy studies have shown that the hydrogen spillover is strongly inhibited by either co-adsorption of CO or a reducing pretreatment with flowing 5% H2/Ar at 673 K. These deactivation effects, however, may be reverted by very mild regeneration treatments at room temperature. Fil: Collins, Sebastián Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Cíes, José M.. Universidad de Cádiz; España Fil: del Río, Eloy. Universidad de Cádiz; España Fil: Lopez Haro, Miguel. Universidad de Cádiz; España Fil: Trasobares, Susana. Universidad de Cádiz; España Fil: Calvino, José J.. Universidad de Cádiz; España Fil: Pintado, José M.. Universidad de Cádiz; España Fil: Bernal, Serafín. Universidad de Cádiz; España

Gold nanoparticles (

Ag nanoparticles of two different sizes (1 and 4 nm) were prepared within an apoferritin cavity by using an Ag+-loaded apoferritin as a nanoconfined environment for their construction. The initial amount of Ag+ ions injected in the apoferritin cavity dictates the size of the final Ag particles. The protein shell prevents bulk aggregation of the metal particles, which renders them water soluble and extremely stable.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Photochemical reduction of tetrachloroaurate (AuCl4-) ions in the highly constrained aqueous domains of a nanostructured ionogel template, formed via self-assembly of the ionic liquid 1-decyl-3-methylimidazolium chloride (C10mim+Cl-) in water, results in the formation of anisotropic gold nanoparticles with a variety of sizes and morphologies, which include previously unattainable trigonal prismatic nanorods. Unexpectedly, small-angle X-ray scattering studies of the Au-ionogel composite reveal that the in situ formation of the nanoparticles increases the mesoscopic order of the ionogel, which results in its conversion to a near-monodomain structure. The findings demonstrate that nanostructured, ionic liquid-based gels can be used to template the formation of new nanoparticle morphologies with technologically important optical, electronic, and catalytic properties. It may also be possible to design soft templates that permit the fabrication of highly ordered nanoparticle array-hydrogel composites, thereby enabling control and tuning of the collective properties of the encapsulated nanoparticles.

In this paper we demonstrate that depending on the surrounding ambient, which may be manifested by different damping conditions, a "bump" in frequency response of Electric Force Microscope (EFM) cantilevers may be observed, either in electrical amplitude or phase signals of AC gradients. This bump is present in air and at room temperature when the cantilever oscillates at fundamental frequency with high excitation amplitude but disappears at increasing temperature. This effect can be explained by a significant temperature decrease of the Q factor of coated cantilevers. At a constant value of AC voltage, the relevant parameter is the ratio of Q factor by cantilever stiffness (of the nth oscillation mode) from which we can predict bump observation. This study highlights significant effects for quantitative EFM studies under different atmospheres and at different temperatures.

Highly graphitised needle-like elongated carbon nanostructures containing encapsulated Ni, are produced by heating alternating thin films of C60 and Ni on a silica plate at 950 °C. High Resolution Transmission Electron Microscopy (HRTEM) studies reveal that these tapering structures are fully filled with Ni and are closed at both ends. The diameters of the needles (ca. 2–5 μm in length) range between 10–20 nm at one end and 30–200 nm at the other. A surprisingly high degree of graphitisation was observed for the nanostructures. They may prove to be useful as Scanning Tunnelling Microscope (STM) tips due to their shape.