Controlled doping of transition metal cations in alumina pillared clays

A two-step method of loading controlled amounts of transition metal cations into alumina pillared clays (Al-PILCs) is proposed. First, calcined Al-PILC was dispersed into an aqueous solution of sodium or ammonium ions. Increasing the pH of the dispersion resulted in an increase in the amount of cations loaded into the clay. The ion-doped Al-PILC was then exchanged with an aqueous solution of transition metal salt at a pH of similar to 4.5 to replace Na+ or NH4+ ions by transition metal cations. Analytical techniques such as atomic absorption spectroscopy, X-ray diffraction, diffuse reflectance-ultraviolet-visible spectroscopy, as well as N-2 adsorption were used to characterize the PILC products with and without the loading of metal ions. The introduced transition metal species exist in the forms of hydrated ions in the PILC hosts. The content of transition metal ions in the final product increased with the amount of Na+ or NH4+ loaded in the first step so that by controlling the pH of the dispersion in the first step, one can control the doping amounts of transition metal cations into Al-PILCs. A sample containing 0.125 mmol/g of nickel was thus obtained, which is similar to 3 times of that obtained by directly exchanging Al-PILC with Ni(NO3)(2) solution, while the pillared layered structures of the Al-PILC remained. The porosity analysis using N-2 adsorption data indicated that most of the doped transition metal ions dispersed homogeneously in the micropores of the Al-PILC, significantly affecting the micropore structure.

Porous clays and pillared clays-based catalysts. Part 2: A review of the catalytic and molecular sieve applications

Metal oxide pillared clay (PILC) possesses several interesting properties, such as large surface area, high pore volume and tunable pore size (from micropore to mesopore), high thermal stability, strong surface acidity and catalytic active substrates/metal oxide pillars. These unique characteristics make PILC an attractive material in catalytic reactions. It can be made either as catalyst support or directly used as catalyst. This paper is a continuous work from Kloprogge's review (J.T. Kloprogge, J. Porous Mater. 5, 5 1998) on the synthesis and properties of smectites and related PILCs and will focus on the diverse applications of clay pillared with different types of metal oxides in the heterogeneous catalysis area and adsorption area. The relation between the performance of the PILC and its physico-chemical features will be addressed.

Carbamazepine oxidation catalyzed by iron and manganese porphyrins supported on aminofunctionalized matrices

This work describes the catalytic activity of manganese and iron porphyrins, Mn and Fe(TFPP)Cl, covalently immobilized on the aminofunctionalized supports montmorillonite K-10 (MontX) and silica (SilX), where X= 1 or 2 represents the length of the organic chain (""arms"") binding the metalloporphyrin to the support. These systems were characterized by UV-vis and Electronic Paramagnetic Resonance (EPR), and they were used as catalysts in the oxidation of carbamazepine (CBZ) by the oxidants iodosylbenzene (PhIO) and hydrogen peroxide. The manganese porphyrin (MnP) catalysts proved to be efficient and selective for the epoxide, the main CBZ metabolite in natural systems. MnMont1 was an excellent catalyst when PhIO was used as oxidant, even better than the same MnP in homogeneous system. Supports bearing short ""arms"" led to the best yields. Although H2O2 is an environmentally friendly oxidant, low product yields were obtained when it was employed in CBZ oxidation. Fe(TFPP)CI immobilized on aminofunctionalized supports was not an efficient catalyst, probably due to the presence of Fe(H) species in the matrix, which led to the less reactive intermediate PFe(IV)(O). (c) 2007 Elsevier B.V. All rights reserved.

Bone mineral apparent density in juvenile dermatomyositis: the role of lean body mass and glucocorticoid use

Objective: To analyse bone mineral density (BMD) in juvenile dermatomyositis (JDM) and its possible association with body composition, disease activity, duration of disease, glucocorticoid (GC) use, and biochemical bone parameters, including osteoprotegerin (OPG) and receptor activator of nuclear factor B (RANKL). Methods: Twenty girls with JDM and 20 controls matched for gender and age were selected. Body composition and BMD were analysed by dual-energy X-ray absorptiometry (DXA) and bone mineral apparent density (BMAD) was calculated. Duration of disease, cumulative GC, and GC pulse therapy use were determined from medical records. Disease activity and muscle strength were measured by the Disease Activity Score (DAS), the Childhood Myositis Assessment Scale (CMAS), and the Manual Muscle Test (MMT). Inflammatory and bone metabolism parameters were also analysed. OPG and RANKL were measured in patients and controls using an enzyme-linked immunosorbent assay (ELISA). Results: A lower BMAD in the femoral neck (p< 0.001), total femur (p< 0.001), and whole body (p=0.005) was observed in JDM patients compared to controls. Body composition analysis showed a lower lean mass in JDM compared to controls (p=0.015), but no difference was observed with regard to fat mass. A trend of lower serum calcium was observed in JDM (p=0.05), whereas all other parameters analysed, including OPG and RANKL, were similar. Multiple linear regression analysis revealed that, in JDM, lean mass (p< 0.01) and GC pulse therapy use (p< 0.05) were independent factors for BMAD in the hip region. Conclusions: This study has identified low lean mass and GC pulse therapy use as the major factors for low hip BMAD in JDM patients.

Parafoveal letter recognition at reduced contrast in normal aging and in patients with risk factors for AMD

Background Patients with early age-related maculopathy ( ARM) do not necessarily show obvious morphological signs or functional impairment. Many have good visual acuity, yet complain of decreased visual performance. The aim of this study was to investigate the aging effects on performance of parafoveal letter recognition at reduced contrast, and defects caused by early ARM and normal fellow eyes of patients with unilateral age-related macular degeneration (nfAMD). Methods Testing of the central visual field (8 radius) was performed by the Macular Mapping Test (MMT) using recognition of letters in 40 parafoveal target locations at four contrast levels (5, 10, 25 and 100%). Effects of aging were investigated in 64 healthy subjects aged 23 to 76 years (CTRL). In addition, 39 eyes (minimum visual acuity of 0.63; 20/30) from 39 patients with either no visible signs of ARM, while the fellow eye had advanced age-related macular degeneration (nfAMD; n=12), or early signs of ARM (eARM; n=27) were examined. Performance was expressed summarily as a ""field score"" (FS). Results Performance in the MMT begins to decline linearly with age in normal subjects from the age of 50 and 54 years on, at 5% and 10% contrast respectively. The differentiation between patients and CTRLs was enhanced if FS at 5% was analyzed along with FS at 10% contrast. In 8/12 patients from group nfAMD and in 18/27 from group eARM, the FS was statistically significantly lower than in the CTRL group in at least one of the lower contrast levels. Conclusion Using parafoveal test locations, a recognition task and diminished contrast increases the chance of early detection of functional defects due to eARM or nfAMD and can differentiate them from those due to aging alone.

Engineering the structures of nanoporous clays with micelles of alkyl polyether surfactants

Composite clay nanostructures (CCNs) were observed in intercalating Laponite clay with alumina in the presence of alkyl polyether surfactants which contain hydrophobic alkyl chains and ether groups. Such nanostructured clays are highly porous solids consisting of randomly orientated clay platelets intercalated with alumina nanoparticles. The pores in the product solids are larger than the dimension of the surfactant molecules, ranging from 2 to 10 nm. This suggests that the micelles of the surfactant molecules, rather than the molecules, act as templates in the synthesis. Interestingly, it is found that the size of the framework pores was directly proportional to the amount of the surfactants in terms of moles, but shows no evident dependence on the size of the surfactant molecules. Broad pore size distributions were observed for the product CCNs. This study demonstrates that introducing surfactants in the pillaring process of clays is a powerful strategy for tailoring the pore structures of nanoporous clays. With this new technique, it is possible to design and engineer such composite clay nanostructures with desired pore and surface properties by the proper choice of surfactant amounts and preparation conditions.

Characterization of pore structure and coordination of titanium in TiO2 and SiO2-TiO2 sol-pillared clays

Titania sol-pillared clay (TiO2 PILC) and silica-titania sol-pillared clay (SiO2-TiO2 PILC) were synthesized by the sol-gel method. Supercritical drying (SCD) and treatment with quaternary ammonium surfactants were used to tailor the pore structure of the resulting clay. It was found that SCD approach increased the external surface area of the PILCs dramatically and that treatment with surfactants could be used to tailor pore size because the mesopore formation in the galleries between the clay layers follows the templating mechanism as observed in the synthesis of MCM-41 materials. Highly mesoporous solids were thus obtained. In calcined TiO2 PILC, ultrafine crystallites in anatase phase, which are active for photocatalytic oxidation of organics, were observed. In SiO2-TiO2 PILCs and their derivatives, titanium was highly dispersed in the matrix of silica and no crystal phase was observed. The highly dispersed titanium sites are good catalytic centers for selective oxidation of organic compounds. (C) 2001 Academic Press.

Molecular engineered porous clays using surfactants

Quaternary ammonium surfactants were used to control the pore structure of bentonite intercalated with a mixed hydro-sol of silicon and titanium. Porous clay heterostructures of alumina and laponite were prepared in the presence of polyethylene oxide (PEO) surfactants. Participation of the surfactants in the synthesis results in significant changes in the structure of porous clay products. Surfactants are involved in different mechanisms, In the case of bentonite, the mean size of the framework pores was directly proportional to the chain length of the quaternary ammonium surfactants. This indicates a molecular templating mechanism, similar to that observed in the synthesis of MCM41. However, in the case of laponite, the size and volume of the mesopores were related to the amount of PEO surfactants used. By using an appropriate surfactant, we can obtain highly porous clays with various pore structures. Introducing surfactants during intercalation is an efficient strategy for the molecular engineering of porous clay adsorbents and catalysts. (C) 2002 Elsevier Science B.V. All rights reserved.

Novel composites of TiO2 (anatase) and silicate nanoparticles

Thermally stable composite nanostructures of titanium dioxide (anatase) and silicate nanoparticles were prepared from Laponite clay and a sol of titanium hydrate in the presence of poly(ethylene oxide) (PEO) surfactants. Laponite is a synthetic clay that readily disperses in water and exists as exfoliated silicate layers of about 1-nm thick in transparent dispersions of high pH. The acidic sol solution reacts with the clay platelets and leaches out most of the magnesium in the clay, while the sol particles hydrolyze further due to the high pH of the clay dispersion. As a result, larger precursors of TiO2 nanoparticles form and condense on the fragmentized pieces of the leached silicate. Introducing PEO surfactants into the synthesis can significantly increase the porosity and surface area of the composite solids. The TiO2 exists as anatase nanoparticles that are separated by silicate fragments and voids such that they are accessible to organic molecules. The size of the anatase particle can be tailored by manipulating the experimental parameters at various synthesis stages. Therefore, we can design and engineer composite nanostructures to achieve better performance. The composite solids exhibit superior properties as photocatalysts for the degradation of Rhodamine 6G in aqueous solution.

Porous solids from layered clays by combined pillaring and templating approaches

The pore structure formation in bentonite, pillared with a mixed sol of silicon and titanium hydroxides and treated subsequently with quaternary ammonium surfactants, is investigated. The surfactant micelles act as a template, similar to their role in MCM41 synthesis. Because both the surfactant micelles and the sol particles are positively charged, it is greatly favorable for them to form meso-phase assembles in the galleries between the clay layers that bear negative charges. Besides, the sol particles do not bond the clay layers strongly as other kinds of pillar precursors do, so that the treatment with surfactants can result in radical structure changes in sol-pillared clays. This allows us to tailor the pore structure of these porous clays by choice of surfactant. The surfactant treatment also results in profound increases in porosity and improvement in thermal stability. Therefore, the product porous clays have great potential to be Used to deal with large molecules or at high operating temperatures. We also found that titanium in these samples is highly dispersed in the silica matrix rather than existing in the form of small particles of pure titania. Such highly dispersed Ti active centers may offer excellent activities for catalytic oxidation reactions such as alkanes into alcohols and ketones.

A randomised controlled trial of methadone maintenance treatment versus wait list control in an Australian prison system

Objectives: The aim was to determine whether methadone maintenance treatment reduced heroin use, syringe sharing and HIV or hepatitis C incidence among prisoners. Methods: All eligible prisoners seeking drug treatment were randomised to methadone or a waitlist control group from 1997 to 1998 and followed up after 4 months. Heroin use was measured by hair analysis and self report; drugs used and injected and syringe sharing were measured by self report. Hepatitis C and HIV incidence was measured by serology. Results: Of 593 eligible prisoners, 382 (64%) were randomised to MMT (n = 191) or control (n = 191). 129 treated and 124 control subjects were followed up at 5 months. Heroin use was significantly lower among treated than control subjects at follow up. Treated subjects reported lower levels of drug injection and syringe sharing at follow up. There was no difference in HIV or hepatitis C incidence. Conclusions: Consideration should be given to the introduction of prison methadone programs particular where community based programs exist. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

Notas sobre depósitos de Taveiro estratigrafia, paleontologia, idade, paleoecologia

This paper reports some research work that has been done to support Geological Survey's field work for the 1:50.000 Carta Geológica de Portugal, (sheets 19-C Figueira da Foz and 19-D Coimbra-Lousã). Its main purpose was to establish the age of some continental formations. At Cerâmica do Mondego, Ld.ª near Taveiro, two series were observed. The lower one is mainly pelitic, montmorillonite being predominant. It also includes some sandy beds and channel deposits with high energy sediments (conglomerate with limestone pebbles). The upper series lies unconformably upon the former, and there is a neat discontinuity surface between the two. It mainly consists of sands, kaolinite being the most abundant of the clay minerals. This seems to indicate an intensive weathering, an acid, well drained environment and transportation by quite high energy running waters. No fossils were recorded. Preliminary paleontological results are presented, along with some data concerning other localities (Aveiro, etc.). Fossils found in the lower series are: gastropoda (Bulimus gaudryi, TV. 15 bed), several vertebrates (TV. 18), fishes (TV. 19?) and plants (TV. 19-TV. 24). Vertebrata belong to the same fauna as that from Vizo, Aveiro, etc. The presence of mammals is most important as only a single tooth was previously Know in Europe (Southern France) in Late Cretaceous formations. Elsewhere there are some mammalian remains in Peru besides the rich assemblages found in the USA and Mongolia. Plants are representative of the «Debeya flora» well known at several localities in Beira Litoral province, in «Buçaco sandstones», and in Lisbon's «Basaltic Complex». The most important stratigraphical conclusion is that the lower series is Upper Campanian and/or Maastrichtian in age, and not Tertiary as sometimes it has been considered. As at Aveiro, «Bebeya flora» occurs in-beds somewhat higher than those with the Aveiro-Vizo-Taveiro vertebrate fauna. Correlation with other «Debeya flora» localities are now more clear. Data concerning Taveiro lower series, in the whole, point out to a rather warm (and moist?) environment in an occasionally (seasonally?) flooded region.

Notas sobre depósitos de Taveiro estratigrafia, paleontologia, idade, paleoecologia

This paper reports some research work that has been done to support Geological Survey's field work for the 1:50.000 Carta Geológica de Portugal, (sheets 19-C Figueira da Foz and 19-D Coimbra-Lousã). Its main purpose was to establish the age of some continental formations. At Cerâmica do Mondego, Lda. near Taveiro, two series were observed. The lower one is mainly pelitic, montmorillonite being predominant. It also includes some sandy beds and channel deposits with high energy sediments (conglomerate with limestone pebbles). The upper series lies unconformably upon the former, and there is a neat discontinuity surface between the two. It mainly consists of sands, kaolinite being the most abundant of the clay minerals. This seems to indicate an intensive weathering, an acid, well drained environment and transportation by quite high energy running waters. No fossils were recorded. Preliminary paleontological results are presented, along with some data concerning other localities (Aveiro, etc). Fossils found in the lower series are: gastropoda (Bulimus gaudryi, TV. 15 bed), several vertebrates (TV. 18), fishes (TV. 19?) and plants (TV. 19-TV. 24). Vertebrata belong to the same fauna as that from Vizo, Aveiro, etc. The presence of mammals is most important as only a single tooth was previously know in Europe (Southern France) in Late Cretaceous formations. Elsewhere there are some mammalian remains in Peru besides the rich assemblages found in the USA and Mongolia. Plants are representative of the «Debeya flora» well known at several localities in Beira Litoral province, in «Buçaco sandstones», and in Lisbon's «Basaltic Complex». The most important stratigraphical conclusion is that the lower series is Upper Campanian and/or Maastrichtian in age, and not Tertiary as sometimes it has been considered. As at Aveiro, «Bebeya flora» occurs in-beds somewhat higher than those with the Aveiro-Vizo-Taveiro vertebrate fauna. Correlation with other «Debeya flora» localities are now more clear. Data concerning Taveiro lower series, in the whole, point out to a rather warm (and moist?) environment in an occasionally (seasonally?) flooded region.

Preparação e caracterização de membranas biodegradáveis

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Química e Bioquímica

Mineralogia da fracção argilosa da Formação de Vale Álvaro (Bragança, NE Portugal)

The studied materials were sampled from several conglomerate and carbonate sandstone units, overlapped for 23 meters. This formation represents a debris flow dominated alluvial fan alternating with quiet sedimentary conditions. These deposits of probably Paleogene age were placed upon mafic and ultramafic rocks that are the exclusive source of sediments. Optical and SEM identification, microanalysis and XRD studies (with decomposition procedures) of clay fractions obtained after high-speed centrifugation were performed in order to characterise the clay minerals content. The results of the analytical program allowed the establishment of the following remarks: a) Fe-rich montmorillonite dominance over paligorskite, chlorite, chlorite-smectite mixed-layers, serpentine and talc; b) smectites in the 12.4 - 15 A range, expanding to about 17 A after EG treatment; c) serpentine and talc as secondary minerals in the interior of altered clasts; d) chlorite and clorite smectite mixed-layer compositions in the borders of the clasts and in the cement. The composition of sediments results from coarse clasts eroded from mafic and ultramafic rocks and clayey material. Clasts show evidences of post-depositional weathering (coatings of chlorite and smectite). Clayey material has the contributions of i) inherired chlorite, smectite and chlorite-smectite mixed-layers; ii ) authigenic crystallisation of Fe-montmorillonite (due to availability of Fe in the crystallising solutions following previous weathering events); iii) authigenic paligorskite associated to a carbonate cement.