GIR-QUESCAT, Departamento de Química Inorgánica, Universidad de Salamanca, 37008 Salamanca, Spain, and Departamento de Ingeniería Química y Química Inorgánica, Universidad de Córdoba, 14071 Córdoba, Spain vrives@usal.es.
The use of urea as a precipitating agent in the synthesis of Ni-Al and Zn-Al layered double hydroxides having a hydrotalcite-like structure via a microwave-hydrothermal method is reported. For comparison purposes, the samples were also prepared by a conventional hydrothermal method. Ni-Al compounds with the hydrotalcite-like structure were obtained in shorter periods of time by the microwave method than by the conventional method, whereas when zinc cations were involved, no successful synthesis was achieved regardless of the method used. In order to find the best synthesis conditions for the Ni-Al solids, samples were submitted to microwave-hydrothermal treatment at different temperatures for increasing periods of time, and the structural, thermal, and textural properties of the synthesized materials were evaluated. All of the solids were fully characterized by chemical elemental analysis, powder X-ray diffraction (PXRD), FT-IR spectroscopy, and transmission and scanning electron microscopy as well as by N 2 adsorption/desorption at -196 degrees C for assessment of specific surface area and porosity. The PXRD patterns showed that the layered structure appeared after merely 10 min when the synthesis was carried out at 125 degrees C; however, the FT-IR spectra showed the presence of some cyanate groups that were formed during urea hydrolysis and were quite difficult to remove completely. When the conventional hydrothermal treatment was used, longer periods of time were required in order to develop the hydrotalcite-like structure, but increasing the aging time improved the crystallinity of the compounds and yielded large particles.
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Unité de catalyse et de chimie de matériaux divisés, Université catholique de Louvain, Croix du Sud, 2/17, 1348 Louvain-La-Neuve (Belgium), Fax:(+32) 10 47 3649.
Hydrotalcites offer unique basic properties that make them very attractive for catalytic applications. It is of primary interest to make use of accurate tools for probing the basicity of hydrotalcite-based catalysts for the purpose of 1) fundamental understanding of base-catalysed processes with hydrotalcites and 2) optimisation of the catalytic performance achieved in reactions of industrial interest. Techniques based on probe molecules, titration techniques and test reactions along with physicochemical characterisation are overviewed in the first part of this review. The aim is to provide the tools for understanding how series of parameters involved in the preparation of hydrotalcite-based catalytic materials can be employed to control and adapt the basic properties of the catalyst towards the basicity demanded by each target chemical reaction. An overview of recent and significant achievements in that perspective is presented in the second part of the paper.
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Sección Departamental Ciencias de la Alimentación, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain; Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
In this contribution, the performance of three different extraction procedures towards the extraction of antioxidants from rosemary (Rosmarinus officinalis) is presented. Namely, pressurized liquid extraction (PLE), using water and ethanol as solvents, supercritical fluid extraction (SFE), using neat CO(2) and supercritical CO(2) modified with ethanol, as well as a novel extraction process called Water Extraction and Particle formation On-line (WEPO) are directly compared. Different extraction conditions including temperatures, times and pressures have been studied. The produced extracts have been characterized in terms of extraction yield, antioxidant activity (using the DPPH radical scavenging method) and total phenols (using the Folin method). Besides, all the extracts have been chemically characterized using a new quantitative UPLC-MS/MS method. This method allowed the determination of the main antioxidants present in rosemary, including, among others, rosmarinic acid, carnosic acid and carnosol, attaining detection limits as low as 2ng/mL. The results obtained in this study show that PLE using ethanol at high temperatures (200 degrees C) was able to produce extracts with high antioxidant activity (EC(50) 8.8mug/mL) and high yield (ca. 40%) while efficiently extracting antioxidants of diverse polarity, among them, carnosic and rosmarinic acids, regarded as the most important antioxidants present in rosemary. Nevertheless, in this work, the ability of the three studied environmentally friendly extraction techniques to obtain bioactives from natural sources is demonstrated.
Department of Subtropical Pomology, Estación Experimental "La Mayora"- CSIC, 29760 Algarrobo-Costa, Málaga, Spain.
Background and Aims Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates. Methods The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically. Key Results A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development. Conclusions A plesiomorphic simple gynoecium hosts a simple pollen-pistil interaction, based on a support-control system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigma-style interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.
Allergy Section, Rio Hortega University Hospital, Valladolid, Spain.
BACKGROUND: Food allergy results from an atypical response of the mucosal immune system to orally consumed allergens. Antacid medication inhibits the digestion of dietary proteins and causes food allergy. A decrease of the gastric pH might enhance the function of digestion and reduce the risk of food allergy. OBJECTIVE: To test a possible decrease in the allergenicity of powerful food allergens (egg, chicken, lentils) with the addition of vinegar during the cooking process. METHODS: We included seven patients who suffered from anaphylaxis due to egg, chicken and lentils. We added vinegar to egg, chicken and lentil processed extracts used for skin prick tests (SPT) and compared the wheal areas obtained with the same extracts sources and the same way but without vinegar addition. Immunodetection was performed with the different processed extracts and patients' sera. Only one patient consented food challenge with vinegar-marinated-chicken. RESULTS: Wheal areas were significantly minor with the food extract with vinegar. Inmunodetection showed a decrease of the response with vinegar processed extracts. CONCLUSIONS: Vinegar addition during the cooking process may decrease lentil and chicken allergenicity.
Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain.
Melatonin is involved in the regulation of both cellular and humoral immunity. In the present study we have evaluated the effect of the oral administration of melatonin and its precursor, the amino acid tryptophan, on humoral immune response in ringdoves (Streptopelia risoria) from different age groups. Male and female ringdoves of 4-5 years of age (young) and 12-14 years of age (old) were used in this study. The animals received a single capsule of 300 mg/kg b.w. of tryptophan (old animals) for 3 consecutive days one hour after lights on or a single oral dose (0.25 or 2.5 mg/kg body weight/0.1 ml per animal/day, young and old animals respectively) of melatonin, for 3 consecutive days 1 hr before lights off. Blood samples were taken before beginning the treatment (basal values) and at the end of the treatment. Immunoglobulins, bactericidal and haemolytic activity were measured. Our results show that in old animals the humoral immune response was reduced with respect to the young. Both melatonin and tryptophan treatment increased the immunoglobulin concentration, with the nocturnal values being significantly higher than diurnal values and with a major effect in old animals. The bactericidal activity of the Streptopelia risoria serum against Staphylococcus aureus, after the treatment with melatonin or tryptophan, was increased at night with a greater effect in old animals. No significant differences were observed in the haemolytic activity of the serum in young animals, but there was an increase in old animals, with higher values at night after treatment with melatonin. In general, the oral administration of melatonin or tryptophan produced a stimulation of humoral immune response with greater effects in old ringdoves.
Stefan Waliszewski,
R Valencia Quintana,
C Corona,
M Herrero,
K Sánchez,
H Aguirre,
I Aldave,
S Gomez Arroyo,
R Villalobos Pietrini
Institute of Forensic Medicine, University of Veracruz, SS Juan Pablo II s/n, 91980, Boca del Río, Mexico, swal@uv.mx.
Since the discovery of insecticide properties of DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) and HCH (hexachlorocyclohexane), they have provided great benefits to humans in sanitary actions to combat the spread of infection-borne disease vectors. Public Health Programs in Mexico used DDT and HCH until 1999 as the insecticides of choice to control disease-transmitting organisms. Because of their persistence and accumulative properties, organochlorine pesticides bioconcentrate in lipids of the human body, reflecting the rate of environmental exposure. Eighty human abdominal adipose tissue samples from Veracruz and 80 samples from Puebla were analyzed and the obtained results were compared among both populations. The results from Veracruz showed higher contamination levels (mg/kg on lipid base) compared to Puebla: beta-HCH, 0.072 vs. 0.029; pp'DDE (Dichlorodiphenyldichloroethylene), 2.364 vs. 0.726; op'DDT, 0.022 vs. 0.025; pp'DDT, 0.192 vs. 0.061; and Sigma-DDT, 2.589 vs. 0.806. The population from Veracruz and from Puebla divided by sex, origin, and cause of death presented no statistical differences. The comparison between sexes (women and men groups) at Veracruz and Puebla indicated significantly higher levels in Veracruz and statistical significant differences. Calculating possible risks (odds ratios, OR), pp'DDE (OR = 5.04) and op'DDT (OR = 2.93) revealed significantly higher risk for the Veracruz population. The study indicated prolonged DDT exposure of Mexicans caused by the past sanitary use and persistence of its residues in soils and air.
Departamento de Química Inorgánica e Ingeniería Química, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, 14071 Córdoba, Spain.
Hydrotalcite-like compounds [Mg(3)Al(OH)(8)]Cl.4H(2)O;[Mg(3)Fe(OH)(8)]Cl.4H(2)O;[Mg(3)Al(0.5)Fe(0.5)(OH)(8)]Cl.4H(2)O (LDHs) and calcined product of [Mg(3)Al(OH)(8)]Cl.4H(2)O, Mg(3)AlO(4.5)(HT500), were studied as potential adsorbents of the herbicide MCPA [(4-chloro-2-methylphenoxy)acetic acid] as a function of pH, contact time and pesticide concentration, and also as support for the slow release of this pesticide, with the aim to reduce the hazardous effects that it can pose to the environment. The information obtained in the adsorption study was used for the preparation of LDH-MCPA complexes. The results showed high and rapid adsorption of MCPA on the adsorbents as well as that MCPA formulations based on LDHs and HT500 as pesticide supports displayed controlled release properties and reduced herbicide leaching in soil columns compared to a standard commercial MCPA formulation. Thereby, we conclude that the LDHs employed in this study can be used not only as adsorbents to remove MCPA from aqueous solutions, but also as supports for the slow release of this highly mobile herbicide, thus controlling its immediate availability and leaching.
Departamento de Caracterización de Alimentos, Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
In the present work, a comprehensive methodology to carry out the screening for novel natural functional compounds is presented. To do that, a new strategy has been developed including the use of unexplored natural sources (i.e., algae and microalgae) together with environmentally clean extraction techniques and advanced analytical tools. The developed procedure allows also estimating the functional activities of the different extracts obtained and even more important, to correlate these activities with their particular chemical composition. By applying this methodology it has been possible to carry out the screening for bioactive compounds in the algae Himanthalia elongata and the microalgae Synechocystis sp. Both algae produced active extracts in terms of both antioxidant and antimicrobial activity. The obtained pressurized liquid extracts were chemically characterized by GC-MS and HPLC-DAD. Different fatty acids and volatile compounds with antimicrobial activity were identified, such as phytol, fucosterol, neophytadiene or palmitic, palmitoleic and oleic acids. Based on the results obtained, ethanol was selected as the most appropriate solvent to extract this kind of compounds from the natural sources studied.
Departamento de Fisiología, Facultad de Ciencias, Badajoz, España.
The aim of this study was to analyze the diets of 39 healthy, lactating women (average age = 34.3 years; average BMI = 26.2 kg/ m2) by a 24-hour dietary recall. This investigation was focused on calcium and vitamin D intake. Nutrients were estimated using the software Dial. These participants were divided into calcium restrictors, defined as calcium intake < 1200 mg/day, and non-restrictors (> 1200 mg/day). The results showed that 64% of the study population (restrictors) reported a mean energy intake (2042.7 +/- 458.3 kcal), calcium intake (812.4 +/- 211.2 mg/day) and vitamin D intake (1.71 +/- 1.59 microg/day) below the adequate intake level (AI) and lower than non-restrictors estimated intakes (p < 0.01). The conclusion of this study is that a high percentage of the lactating women consume a diet below nutritional recommendations during this stage. It is recommended that health professionals should inform these mothers about the correct dietary habits during this period.
Fulvio Brunetti,
M Herrero,
Juan Muñoz,
Angel Díaz-Ortiz,
Jessica Alfonsi,
Moreno Meneghetti,
Maurizio Prato,
Ester Vázquez
prato@units.it, ester.vazquez@uclm.es.
We describe a new synthetic strategy to produce multifunctionalized carbon nanotubes using a combination of two different addition reactions, the 1,3-dipolar cycloaddition of azomethine ylides and the addition of diazonium salts, both via a simple and fast microwave-induced method. The presence of multifunctionality on the SWNTs has been confirmed using the most useful techniques for the characterization of carbon nanotubes. The doubly functionalized SWNTs can be considered potentially useful for many interesting applications.
Departamento de Educación Física, Facultad de Ciencias de la Actividad Física y el Deporte, Universidad de Las Palmas de Gran Canaria, 35017 Canary Islands, Spain.
This paper reflects on the factors that condition performance in powerlifting and proposes that the result-generating process is inadequately described by the allometric equations commonly used. We analysed the scores of 1812 lifters belonging to all body mass categories, and analysed the changes in the results achieved in each weight category and by each competitor. Current performance-predicting methods take into account biological variables, paying no heed to other competition features. Performance in male powerlifting (as in other strength sports) behaves as a self-organised system with non-linear interactions between its components. Thus, multiple internal and external elements must condition changes in a competitor's score, the most important being body mass, body size, the number of practitioners, and the concurrency of favourable factors in one individual. It was observed that each behaved in a specific form in the high level, according to the individuals' circumstances, which make up the main elements of the competitive system in every category. In powerlifting, official weight categories are generally organised in three different groups: light (<52.0 to <60kg), medium (<67.5 to <90.0kg) and heavy (<100 to >125kg) lifter categories, each one of them with specific allometric exponents. The exponent should be revised periodically, especially with regard to the internal dynamics of the category, and adjusted according to possible changes affecting competition.
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Institute of Nano-Science and Technology, College of Physics and Technology, Central China Normal University, Wuhan 430079, People's Republic of China.
This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni(2+)-Fe(3+) layered double hydroxides (LDHs). Flower-like Ni(2+)-Fe(3+) LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degrees C in nitrogen gas, porous NiO/NiFe(2)O(4) nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni(2+)-Fe(3+) LDHs as well as porous NiO/NiFe(2)O(4) nanosheets.
Phosphate uptake behavior of ZnAlZr ternary layered double hydroxides through surface precipitation.
Discipline of Inorganic Materials and Catalysis, Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, GB Marg, Bhavnagar 364 002, India.
Tetravalent Zr(4+) ion incorporated ZnAl hydrotalcite-like material with varying Zn/(Al+Zr) atomic ratio (2-4) and Al/Zr atomic ratio 0.7:0.3 with CO(3)(2-) as interlayer anion were successfully synthesized and characterized by various physicochemical methods. The phosphate uptake studies were carried out over these materials by batch method with the objective of enhancing the uptake through creation of higher positive charge on brucite-like layers by the incorporation of Zr(4+). The studies revealed that ternary ZnAlZr hydrotalcites show good uptake capacity for phosphate, among which ZnAlZr4-HT depicts a maximum uptake of around 91mgP/g. We observed that phosphate uptake results in the formation of layered hopeite mineral (Zn(3)(PO(4))(3).4H(2)O) on the surface of material by the surface precipitation of dissolved zinc ion through the outer-sphere complex formation of phosphate. The phosphate uptake increases with a decrease in Zn/Al and Zn/(Al+Zr) atomic ratios. Effects of initial phosphate concentration, contact time, adsorbent amount and temperature variation on phosphate uptake were studied. Co-presence of competitive anion like nitrate enhances the uptake of phosphate to 148mgP/g. Recycle studies of the material shows a decrease in the uptake of phosphate with the number of cycles due to an increase in the crystallinity. Very high uptake of phosphate by these materials even in the presence of other anions/cations suggests their potential role in waste water remediation.
Department of Chemistry, Faculty of Sciences, Azarbaijan University of Tarbiat Moallem, Tabriz, Iran, h-valizadeh@azaruniv.edu.
Microwave-assisted condensation of salicylaldehydes and N-methyl hydroxylammonium hydrochloride in the presence of K(2)CO(3) under solvent-free conditions afforded, unexpected N-methylbenzo[d]isoxazolium hydroxides (2a-d).
Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China. weifei@flotu.org.
Hierarchical SAPO-34 zeolite with high crystallinity and excellent hydrothermal stability was directly synthesized in the nanoscale confined environment provided by the natural layered material kaolin.
College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060, PR China; College of Materials and Chemical Engineering, Zhejiang University, Hangzhou 310027, PR China.
Nanosized copper aluminate (CuAl(2)O(4)) spinel particles have been prepared by a precursor approach with the aid of ultrasound radiation. Mono-phasic copper aluminate with a crystallite diameter of 17nm along the (311) plane was formed when the products were synthesized using Cu(NO(3))(2).6H(2)O and Al(NO(3))(3).9H(2)O as starting materials, with urea as a precipitation agent at a concentration of 9M. The reaction was carried out under ultrasound irradiation at 80 degrees C for 4h and a calcination temperature of 900 degrees C for 6h. The synthesized copper aluminate particles and the effect of different processing conditions such as the copper source, precipitation agents, sonochemical reaction time, calcination temperature and time were analyzed and characterized by the techniques of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transformation infrared spectroscopy (FT-IR).
Departamento de Quimica, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Sala 67, Ouro Preto-MG, 35400-000, Brazil, and Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, C.P. 702, Belo Horizonte-MG, 30123-970, Brazil.
Ba(Mn(1/3)Nb(2/3))O(3) ceramics were synthesized by the microwave-hydrothermal process. Crystalline, single-phase, needle-like materials were obtained with high anisotropy and aspect ratio. Large crystals could be prepared from a direct combination of nanosized crystals under microwaves through an oriented attachment mechanism. Infrared and Raman spectroscopies showed perfect agreement with group-theoretical approaches for a trigonal, P3m1 structure. Franck-Condon modes were identified in Raman scattering experiments conducted in different wavelengths, laser powers, and temperatures. The results showed that the Mn ions exhibit a particular role in the lattice dynamics in complex perovskites.
MOE Key Laboratory for the Magnetism and Magnetic Materials and Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, China.
Sea-urchin-like Ni nanoparticles based on radial cones with the diameters of 30-50 nm and the lengths of 150-300 nm were synthesized by a wet chemical reduction method. The microwave properties of the Ni nanoparticle-paraffin wax composites with 11.5 vol%, 18.2 vol%, and 23.3 vol% of the sea-urchin-like Ni nanoparticles were measured in the 0.1-18 GHz frequency range. The imaginary part of complex permeability shows two broad resonance peaks due to the natural and exchange resonance. The natural resonance peak appears at a relatively higher frequency of 4.3-4.7 GHz because of the large shape anisotropy of sea-urchin-like particles. The natural resonance peak shifts to lower frequency with increasing volume fraction of the Ni nanoparticles.
Department of Chemical Engineering, Inha University, Incheon 402-751, Republic of Korea.
AlPO(4)-5 and its chromium-containing analogue, CrAPO-5, were prepared using aluminum dross in the presence of triethylamine as a structure directing agent; both Al dross powder and an extracted precipitate from Al dross in an alkali solution were used as an aluminum source. These materials were characterized by XRD, BET surface area measurement, SEM, EDX, XRF, ESR, and UV-vis spectroscopy. Their textural properties were found close to those of the corresponding reference samples prepared using pure Al(OH)(3). CrAPO-5 samples prepared from the aluminum dross were tested as a catalyst for liquid phase oxidation of tetralin using t-butyl hydroperoxide as an oxidizing agent, which showed virtually identical catalytic performances to that obtained by a reference CrAPO-5 catalyst.
Department of Chemistry, University of Calgary, 2500 University Dr NW, Calgary, Alberta, Canada T2N 1N4.
We report a very simple precipitation route to prepare a layered perovskite-type structure, tungsten trioxide hydrate (TTH), with the nominal chemical formula of WO(3).1.3H(2)O ( identical with 1/2H(2)W(2)O(7).1.6H(2)O), using aqueous Na(2)WO(4) and SrCl(2). Our investigation shows that the concentration of HCl used to dissolve the SrCl(2) plays a crucial role in the stabilization of different structure types of layered TTHs. Highly acidic SrCl(2)(dissolved in 9 M HCl) solution yields an orthorhombic layered TTH of WO(3).2H(2)O, while SrCl(2) dissolved in 3 M HCl appears to give an A-site-deficient Ruddlesdon-Popper (RP) related double-perovskite-type layered structure (DOLS-TTH). A well-known scheelite-type structure is obtained under weakly basic conditions (pH = 10.3 for Na(2)WO(4(aq)), 7.0 for SrCl(2(aq))). Previously, RP-type a DOLS of H(2)W(2)O(7).0.58H(2)O was prepared, using an acid-leaching method, from the corresponding n = 2 member of the layered Aurivillius phase (AP) Bi(2)W(2)O(9). Powder X-ray diffraction showed the formation of layered RP DOLS with a large d spacing approximately 12.5 A, which is consistent with acid-leaching (Kuto et al. Inorg. Chem. 2003, 42, 4479-4484; Wang et al. J. Solid State Chem. 2007, 180, 1125-1129) and exfoliation (Schaak et al. Chem. Commun. 2002, 706-707) methods for synthesized TTHs. The proposed DOLS-TTH structure of newly prepared TTHs was further confirmed by an intercalation reaction using n-octylamine (C8A). A transmission electron microscopy study showed the formation of nanosized particles, and scanning electron microscopy coupled with energy dispersive X-ray analysis showed the absence of Na and Sr in the air-dried, as-precipitated products under acidic conditions. The bulk electrical (proton) conductivity of presently prepared TTHs was found to be on the order of 10(-4)-10(-3) S/cm at room temperature in wet N(2).
Center for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, B-3001, Leuven, Belgium. bert.sels@biw.kuleuven.be.
Nanocrystalline tungstate-exchanged layered double hydroxides of the takovite type,[Ni(x)Al(1-x)(OH)(2)](NO(3))(0.9-x)(WO(4))(0.05).mH(2)O, have been prepared with changing values of x. The morphology-texture parameters of the synthesized materials were characterized by using scanning electron microscopy and nitrogen adsorption techniques. X-Ray diffraction, diffuse reflectance spectroscopy,(27)Al MAS NMR and infrared spectroscopy were applied to study the structure and the phase purity of the tungstate exchanged materials. Identification of the tungsten state was attempted by infrared and Raman spectroscopy. The catalytic properties of the pure tungstate exchanged takovites were tested in the bromide-assisted epoxidation of terpenic olefins using H(2)O(2) as environmental benign oxidant. The bromide-assisted oxidation shows very interesting chemo-selectivity for various substrates with unique regio- and stereo-selectivity often opposite to that of many traditional methods. The activity of the tungstate catalyst was observed to highly depend on the Al content in the takovite support, most likely due to efficient charge shielding at the catalyst's surface. Tungstate exchanged on Al-rich takovite has a remarkable oxidation activity in terms of turnover frequency. Moreover, the takovite catalyst was found to be stable under reaction conditions and recyclable.


