Prehydrolyzed Tetraethyl Orthosilicate Research Articles

Ordered Mesoporous Graphitic Carbon/Iron Carbide Composites with High Porosity as a Sulfur Host for Li-S Batteries.

The lithium-sulfur battery (LSB) is a promising candidate for future energy storage but faces technological challenges including the low electronic conductivity of sulfur and the solubility of intermediates during cycling. Additionally, current host materials often lack sufficient conductivity and porosity to raise the sulfur loading to over 80 wt %. Here, ordered mesoporous graphitic carbon/iron carbide nanocomposites were prepared via an evaporation-induced self-assembly process using soluble resol, prehydrolyzed tetraethyl orthosilicate (TEOS), and iron(III) chloride as the carbon, silica (SiO2), and iron precursors, respectively. Graphitization and SiO2 etching were conducted simultaneously via Teflon-assisted, solid-state decomposition at high temperature. A high surface area (∼3100 m2 g-1), large pore volume (∼3.3 cm3 g-1), and graphitized carbon frame were achieved, giving a high sulfur loading (85 wt %) while tolerating volumetric expansion during discharge. Electrochemical testing of a LSB containing the composite/sulfur cathode exhibited a superior reversible capacity exceeding 1300 mAh g-1 at a moderate current (C/10) and a low decay in capacity of 9% after 500 cycles at C/5. The interaction between mesoporous graphitic carbon and sulfur is proposed.

Simultaneous control of rod length and pore diameter of SBA-15 for PPL loading

Mesoporous silica materials are attractive materials for immobilizing enzymes because of their well-ordered structures, large surface area are pore volume. Diffusion of large enzyme molecules such as porcine pancreatic lipase (PPL) through the lengthy channels of MPS takes place too slowly. Therefore, the squat of the enzyme at the pore mouth entrance, actually makes the rest of the channel useless. In this study, to overcome this problem, synthesis parameters of SBA-15 were changed, since along with pore diameter increasing, the mesochannel length becomes shorter. The main point to obtain a well-ordered 2D hexagonal pore structure was the pre-hydrolysis of tetraethyl orthosilicate (TEOS) before the addition of 1,3,5-trimethyl benzene as a micelle swelling agent. Due to the strong effect of zirconium in changing the morphology of SBA-15 particles, we modified SBA-15 in the presence of a small amount of ZrOCl2 in the synthesis solution under acidic conditions. As a result, mesochannel length of SBA-15-Zr was shortened from 600 to <200 nm. The morphology of mesoporous silica was also changed from rod-like to platelet, because of the accelerating effect of Zr(IV) on the self-assembly rate of P123 and TEOS condensation. Characteristic results conducted by low angle XRD, high resolution transmission electron microscopy and nitrogen adsorption, confirmed tuning effect of Zr(IV) in SBA-15. Furthermore, it was shown that the number of pore entrances increases with decreasing the length of SBA-15 mesochannels, leading to obvious improvement of enzyme uptake. PPL has been successfully immobilized in the mesoporous channels of SBA-15-Zr. The total amount of lipase adsorbed on the mesoporous SBA-15-Zr was measured by thermal gravimetric analysis. The largest PPL adsorption capacity was 784 mg/g belonging to the SBA-15-Zr with the length of 150 nm and the mean pore size diameter of 9.22 nm.

Highly Luminescent Hybrid SiO&lt;SUB&gt;2&lt;/SUB&gt;-Coated CdTe Quantum Dots Retained Initial Photoluminescence Efficiency in Sol–Gel SiO&lt;SUB&gt;2&lt;/SUB&gt; Film

A highly luminescent silica film was fabricated using tetraethyl orthosilicate (TEOS) and 3-aminopropyltrimethoxysilane (APS) through a controlled sol-gel reaction. The pre-hydrolysis of TEOS and APS which resulted in the mixture of TEOS and APS in a molecular level is a key for the formation of homogenous films. The aminopropyl groups in APS play an important role for obtaining homogeneous film with high photoluminescence (PL). Red-emitting hybrid SiO2-coated CdTe nano-crystals (NCs) were fabricated by a two-step synthesis including a thin SiO2 coating via a sol-gel process and a subsequent refluxing using green-emitting CdTe NCs. The hybrid SiO2-coated CdTe NCs were embedded in a functional SiO2 film via a two-step process including adding the NCs in SiO2 sol with a high viscosity and almost without ethanol and a subsequent spinning coating. The hybrid SiO2-coated CdTe NCs retained their initial PL efficiency (54%) in the film. Being encapsulated with the hybrid NCs in the film, no change on the absorption and PL spectra of red-emitting CdTe NCs (632 nm) was observed. This indicates the hybrid NCs is stable enough during preparation. This phenomenon is ascribed to the controlled sol-gel process and a hybrid SiO2 shell on CdTe NCs. Because these films exhibited high PL efficiency and stability, they will be utilizable for potential applications in many fields.

Preparation, characterization, and adsorption evaluation of chitosan-functionalized mesoporous composites

Polymer-modified mesoporous silica materials are of practical interest due to their great potential for adsorption-related applications. In the present work, composites of natural polymer chitosan (CTS) and siliceous mesoporous SBA-15, i.e. SBA-15/CTS(5%), SBA-15/CTS(10%), and SBA-15/CTS(20%), were facilely prepared by prehydrolysis of tetraethyl orthosilicate in the presence of pore-directing agent and subsequent cocondensation with an appropriate amount of CTS-based organosilane. The texture and composition of pure SBA-15 and CTS-functionalized mesoporous products were characterized using various techniques such as TEM, XRD, N2 adsorption/desorption, 29Si MAS NMR, FT-IR, and TGA measurements. To disclose the adsorption properties of the composites, anionic compound acid red 18 (AR18) was selected as model adsorbate. The effects of pH, ionic strength, contact time, adsorption temperature, and initial concentration of AR18 on adsorption efficiency were investigated. It was found that pure SBA-15 had a negligible adsorption capacity while the CTS-functionalized composites showed large adsorption capacities (up to 232.6mgg−1) with rapid adsorption kinetics (less than 120min). It was also observed that the adsorption capacity increased with increase in CTS content of the composite. Results of comparative analysis indicated that SBA-15/CTS(20%) had better adsorption capacity than most of common adsorbents. Experimental kinetic and isotherm data were analyzed by theoretical models including pseudo-first-order and pseudo-second-order kinetics, Weber–Morris diffusion, Freundlich and Langmuir models. Moreover, adsorption thermodynamics has also been evaluated. The study suggests that the CTS-functionalized mesoporous composites are prospective adsorbents for adsorption of anionic compounds, and somewhat exemplifies their adsorbent function for adsorbing some other adsorbates.

Sarcosine Oxidase Encapsulated Polyvinyl Alcohol-Silica-AuNP Hybrid Films for Sarcosine Sensing Electrochemical Bioelectrode

The amperometric response of sarcosine was measured in aqueous media containing ferrocene monocarboxylic acid using the redox enzyme sarcosine oxidase (SOD) immobilized in a composite material based on polyvinyl alcohol (PVA) and partially prehydrolyzed tetraethyl orthosilicate (pphTEOS) at the surface of “in-house” fabricated graphite electrodes. For comparison, separate electrodes consisting of silver and gold nanoparticles (Ag/AuNPs) embedded in the PVA-pphTEOS matrix was prepared employing a novel sol-gel process based on the in situ chemical reduction of Ag or Au ions using PVA both, as a reducing agent and stabilizer. The analytical performance of the enzyme electrodes was studied in terms of linear ranges, sensitivities, response times, limits of detection, reproducibility and stability.

Prehydrolysis approach to direct synthesis of Fe, Al, Cr-incorporated SBA-15 with good hydrothermal stability and enhanced acidity

The Fe-incorporated mesoporous SBA-15 materials with the Fe content up to a Fe/Si molar ratio=0.05 were synthesised via pre-hydrolysis of tetraethyl orthosilicate (TEOS) employing P123 triblock copolymer as the template. The synthetic strategy is the hydrolysis of Fe salt precursor can provide acidic medium essential for the pre-hydrolysis of TEOS. Different Fe/Si ratios and TEOS pre-hydrolysis periods were employed to modify the structure and texture of the Fe-incorporated SBA-15. The impact of Fe sources (ferric nitrate, ferric chloride, and ferric sulfate) on the characteristics of Fe-SBA-15 has also been investigated. Ferric nitrate showed the best effect among the three Fe sources. UV–Vis study reveals that besides the four-coordinated iron species, the iron oxide domains may also exist in the samples. Pyridine adsorption IR study demonstrates enhancement in Brønsted and Lewis acidity of as-synthesised Fe-SBA-15 materials, potential as solid acid catalyst or catalyst support. Moreover, the employed treatments (700°C for 10h in air and 600°C for 3h in 100% steam) verified good thermal and hydrothermal stability of the derived Fe-SBA-15. For comparison, Al- and Cr-incorporated SBA-15, with the Al/Si and Cr/Si molar ratio of 0.08 and 0.05 respectively, were also synthesised through the same strategy.

CO2 Capture by As-Synthesized Amine-Functionalized MCM-41 Prepared through Direct Synthesis under Basic Condition

The as-synthesized amine-functionalized MCM-41 material was prepared through direct synthesis by co-condensation of tetraethyl orthosilicate (TEOS) with 3-aminopropyl triethoxysilane (APS) at different molar ratios and a pH of approximately 13 for CO2 capture under various CO2 concentrations, temperatures, and moistures. The prepared as-synthesized APS-functionalized MCM-41 (as-APS/MCM) possessed nitrogen content up to 3.46 mmol N/g and CO2 adsorption capacities up to 1.18 mmol/g under 15% CO2 in N2 at 35 °C and 1.74 mmol/g under pure CO2 at 25 °C. The CO2 adsorption capacity was 73% higher than the APS-grafted calcined MCM-41 prepared by postmodification. Because the CO2 adsorption capacity of the as-APS/MCM was found to come mainly from the coated APS rather than the incorporated APS, prehydrolysis of TEOS and post-treatment including template removal and APS neutralization were not required. Dynamic adsorption–desorption cycles revealed that the as-APS/MCM possessed high thermal stability for CO2 capture.

Glucose Oxidase Encapsulated Polyvinyl Alcohol–Silica Hybrid Films for an Electrochemical Glucose Sensing Electrode

An amperometric glucose enzyme electrode was developed by the immobilization of glucose oxidase (GOD) in a composite material based on polyvinyl alcohol (PVA) and partially prehydrolyzed tetraethyl orthosilicate (pphTEOS) on the surface of "in-house" fabricated graphite electrodes. For comparison, silver and gold nanoparticles (Ag/AuNPs) embedded in the PVA-pphTEOS matrix was prepared through a novel method via sol-gel process based on the in situ chemical reduction of Ag or Au ions using PVA as a reducing agent and stabilizer. The successful incorporation of Ag and AuNPs ranging from 5 to 7.5 and 4.5-11 nm, respectively, in the PVA-pphTEOS matrix was confirmed by UV-Vis spectroscopy, TEM, and EDX analysis. The PVA-TEOS matrix was also characterized by FTIR spectroscopy. The analytical performance of the enzyme electrodes were studied in terms of linear ranges, sensitivities, response times, limits of detection, reproducibility and stability.

Synthesis and characterization of silica microcapsules using a sustainable solvent system template

We report direct encapsulation of a sustainable solvent system in silica microcapsules via a sol–gel reaction of silica precursor for potential application of thermoplastic self healing polymeric system. The silica microcapsules were realized by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) using aqueous glycerol microemulsion as template. The pre-hydrolysis of TEOS was found to be useful to obtain isolated free flowing silica microcapsules. Furthermore, the effects of different parameters viz. temperature, rotor speed, the solvent/TEOS ratio on the synthesis of silica microcapsules are studied. A novel micro compression technique to study mechanical properties of the silica microcapsules is reported. The silica microcapsules reported were found to have better mechanical properties compared to incumbent Urea-Formaldehyde (UF) based organic microcapsules.

The Preparation of Bioactive Glass Microspheres in W/O Emulsion

The emulsion combining sol-gel method was used to prepare spherical bioactive glass in the present work. This method involves a two-stage synthesis process: the pre-hydrolysis of tetraethyl orthosilicate (TEOS) in an aqueous acidic solution using templates, and afterward the fabrication of silica spheres by pH induced rapid gelation in a W/O emulsion. Through controlling the two stages separately, the particle size and morphology of silica spheres can be adjusted. These results indicated that emulsion method could supply a good way to prepare glass microspheres.

Tuning pore diameter of platelet SBA-15 materials with short mesochannels for enzyme adsorption

A novel route for preparing highly ordered platelet SBA-15 materials with short mesochannels (ca. 200 nm) and large pore diameters up to 12 nm is reported for the first time. Appropriate quantities of Zr(IV) ions and trimethylbenzene (TMB) were added to the conventional SBA-15 synthesis solution to obtain platelet SBA-15 (SBA-15-p) materials with expanded pores. Based on the results of conventional characterization techniques and in situsmall-angle X-ray scattering experiments, the key step to obtain a well-ordered 2D hexagonal pore structure without vesicle contamination was the pre-hydrolysis of tetraethyl orthosilicate (TEOS) in the Zr(IV) containing synthesis solution for about 25 min before adding TMB as the pore swelling agent. The resultant SBA-15-p materials had high surface areas (∼800 m2 g−1), large pore volumes (∼1.2 cm3 g−1) and short mesochannels (∼200 nm). More importantly, the mesopore diameters Φa_BdB, analyzed by a modified Broekhoff-de Boer method with the Frenkel-Halsey-Hill equation (BdB-FHH) on the nitrogen adsorption isotherms, could be finely tuned to 7–12 nm by varying the amount of swelling agent and the hydrothermal temperature. When adsorbing cytochrome c enzyme at pH 4–10, the short-channel SBA-15-p materials demonstrated higher adsorption capacities and adsorption rates compared to conventional fiber-like SBA-15 materials (SBA-15-f). Furthermore, the uptakes of cytochrome c enzyme per surface area increased significantly on the large pore materials.

Cycloaddition of carbon dioxide for commercially-imperative cyclic carbonates using ionic liquid-functionalized porous amorphous silica

Ionic liquid functionalized mesoporous silicas (IFMSs) were prepared from the coupling of 1-(triethoxysilylpropyl)-3- n-alkylimidazolium halides with tetraethyl orthosilicate (TEOS) through template-free condensation under strong acidic conditions. Optimal synthesis conditions and maximum incorporation of the active sites were achieved through varying the parameters of the co-condensation method. The obtained amorphous silica having 0.20–0.93 mmol of RIm + X − groups showed a surface area between 477 and 672 m 2/g with pore sizes from 3.2 to 7.8 nm. The materials synthesized under various TEOS pre-hydrolysis had larger surface areas, pore volumes, and average pore diameters than those synthesized without pre-hydrolysis. FT-IR, TG/DTG (thermogravimetry/differential thermogravimetry), and solid-state NMR showed that all the immobilized ionic liquid (IIL) groups were incorporated without affecting the organic moieties. Chemical fixation of carbon dioxide was studied at various carbon dioxide pressures by correlating reactivity with various parameters such as surface area, pore volume, pore size, percentage of active sites, type of counter ion, and length of the organic moiety extending from the alkyl halide.

AlPO4-18 Seed Layers and Films by Secondary Growth

AlPO4-18 layers were prepared on Si wafers via spin-coating or the Langmuir−Blodgett (LB) method using nanosized crystals. Multilayers were deposited by spin-coating, whereas the seeds assembled by the LB technique were monolayers. The seeded layers were not stable upon secondary growth under microwave radiation, and no films were formed on the supports. Dense AlPO4-18 films could be obtained by secondary growth after stabilization of the seed layers by adding prehydrolyzed tetraethylorthosilicate (TEOS) to the colloidal AlPO4-18 suspension prior to support seeding. The stabilized seed layers and the grown AlPO4-18 films were stable. The structure and the morphology of the films grown using the two types of seeded supports were similar, independent of the method used for seeding. The AlPO4-18 nanocrystals used for seeding showed very high water capacity with low temperatures of water removal when heated. The layers and films prepared are of potential interest for sensing, heat pump, and cooling machines a...

Micrometer‐sized monodispersed silica spheres with advanced adsorption properties

AbstractMicrometer‐sized monodispersed mesoporous silica spheres with adjustable particle diameter and adjustable pore structure were successfully prepared. Drops of a silica sol were injected by a microfluidic device into a heated oil bath where the droplets solidified during sedimentation. Drop size was varied by control of the rates of the oil flow past the silica sol injector. The silica sol was made by prehydrolysis of tetraethyl orthosilicate (TEOS) in an aqueous acidic solution using a triblock copolymer as the template. Acrylamide monomer was added in the sol after prehydrolysis to accelerate the solidification rate of drops in the oil bath. The amount of monomer was used to control the pore sizes in the silica particles. The effect of synthesis conditions on the morphology and pore structure of spheres was investigated. Silica spheres with different surface morphology and internal structure were obtained by changing the composition of sedimentation medium. Pore diameter and pore‐size distribution can be adjusted effectively by controlling the concentration of silica source, acid or polymeric monomer in the aqueous phase. The prepared silica spheres have high‐surface area (&gt;550 m2/g), large pore volume (&gt;1.1 cm3/g) and large amount of macropores. High‐protein adsorption capacity (520mg/g) was achieved in the adsorption experiments of bovine serum albumin (BSA). Pore structure of silica spheres was demonstrated to be a crucial factor to determine the protein adsorption capacity. © 2007 American Institute of Chemical Engineers AIChE J, 2008

Propylsulfonic Acid-Functionalized Mesoporous Silica Synthesized by in Situ Oxidation of Thiol Groups under Template-Free Condition

Propylsulfonic acid-functionalized mesoporous silica was prepared through in situ oxidization of mercaptopropyl groups with H2O2 during a template-free condensation of tetraethyl orthosilicate (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) under strong acidic condition. The obtained materials with 3−15 mol % loadings of sulfonic acid groups had surface areas up to 700 m2/g and pore sizes around 3.5 nm. The materials synthesized with TEOS prehydrolysis had larger surface areas, pore volumes, and average pore diameters than those synthesized without TEOS prehydrolysis. IR, TG, solid-state NMR, and S K-edge XANES analyses showed that all the mercaptopropyl groups were completely converted to propylsulfonic acid groups without decomposition of the organic moieties using H2O2 as the in situ oxidant in the synthesis procedure. The accessibilities of sulfonic acid centers were determined by ion-exchange with cations of various sizes. The functionalized materials were used as acid catalysts in esterification of acetic acid with methanol and acetalization of chlorobenzaldehyde with methanol. The results showed that the propylsulfonic acid-functionalized mesoporous silica prepared with TEOS prehydrolysis and in situ oxidation had similar catalytic activities as propylsulfonic acid-functionalized SBA-15 but higher than the counterparts synthesized without TEOS prehydrolysis or by postoxidation of mercaptopropyl groups with H2O2.

Template-free synthesis of mesoporous phenylsulfonic acid functionalized silica

Mesoporous silica functionalized with phenylsulfonic acid was prepared by a simple template-free co-condensation of tetraethyl orthosilicate (TEOS) and 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CETS) under strong acidic condition. The obtained materials with 3–15 mol% loadings of phenylsulfonic acid were X-ray amorphous, but had large surface areas (420–620 m 2/g) and narrow pore-size distributions (0.3–1.0 nm PSD, estimated from the peak width at half maximum height) with pore diameters in the range of 3.5–5.0 nm. TEOS hydrolysis prior to the addition of CETS was found to be important in order to obtain functionalized silica materials of large mesopores and pore volumes. IR, TG and solid state NMR studies showed that most of the phenylsulfonic acid groups were incorporated into the silica materials without decomposition during the synthesis procedure. Moreover, most of the sulfonic acid sites are accessible by large cations such as tetramethylammonium (TMA +) and tetrabutylammonium (TBA +) ions. The materials were examined as acid catalysts in esterification of acetic acid with methanol and acetalization of chlorobenzaldehyde with methanol. The results showed that the functionalized amorphous silica materials synthesized with TEOS pre-hydrolysis had similar catalytic activities as that of phenylsulfonic acid-functionalized SBA-15, but higher activities than those of the counterparts synthesized without TEOS pre-hydrolysis or the propylsulfonic acid functionalized SBA-15.

Heteropolyacids with Keggin structure supported on silica-alumina

The behaviour of molybdophosphoric acid, with Keggin structure, supported on different silica-alumina mixtures, obtained by sol-gel method, was studied. Different techniques were used to synthesise the supports. In one of them, commercial alumina was added to a tetraethyl orthosilicate (TEOS) solution, and then this was hydrolysed. In the other preparations, TEOS and aluminium tri-sec-butoxide were hydrolysed, simultaneously or with TEOS prehydrolysis. The catalysts were prepared by incipient wetness impregnation, and different thermal treatments were applied after their leaching with toluene. The specific surface area of the solids was measured, and the nature of the Keggin heteropolyacid species present in the catalysts was characterised by diffuse reflectance spectroscopy and X-ray diffraction. In addition, their acidic properties were evaluated by potentiometric titration with n-butylamine.

Controlled Growth of Pt-Containing SiO2 Nanotubes with High Aspect Ratios

Rectangular prisms of [Pt(NH3)4](HCO3)2 were grown from its aqueous solution by solvent modification with ethanol. The polydispersity of the prisms, being influenced by temperature, the rate of ethanol addition, and the Pt concentration in the aqueous solution, actually results from the iso-oriented aggregation of primary nanofibers into bundles. The employment of prehydrolyzed tetraethyl orthosilicate (TEOS) as a capping agent can effectively stabilize the primary nanofibers. With this stabilized nanofiber as a structure-directing agent, about 100−200 nm thick and up to 40 μm long SiO2 nanotubes, which contain up to 40 wt % of Pt, could be synthesized by further addition of TEOS. The capping mechanism of hydrolyzed TEOS can be reasonably explained through the selective adsorption of silanol species on specific surfaces of primary nanofibers. In our method, the ingenious employment of TEOS as the reactant for the nanotube formation and also as a capping agent avoids the introduction of additional substanc...

Catalytic applications of aminopropylated mesoporous silica prepared by a template-free route in flavanones synthesis

Aminopropylated silica containing mesopores was prepared by a simple sol–gel process with tetraethyl orthosilicate (TEOS) and aminopropyltriethoxysilane (APTES) under strong acidic condition. The materials were characterized by N 2 sorption, TGA, FTIR, and solid-state NMR measurements. It was proved that the amount of APTES in the initial mixture and the preparation process had a great influence on the textural properties of the hybrid organic–inorganic materials. The samples prepared by TEOS prehydrolysis and an appropriate amount of APTES (equal to or less than 10 mol%) contained mesoporous structures of narrow pore size distribution and possessed a larger surface area and pore volume than that prepared without TEOS prehydrolysis. The materials were used as catalysts in the Claisen–Schmidt condensation between substituted benzaldehydes and substituted 2′-hydroxyacetophenones and the subsequent isomerization of the 2′-hydroxychalcone intermediates in the liquid phase. The results showed that the presence of an appropriate amount of aminopropyl groups and narrow distributed mesopores was important for good performance of the catalysts. Good catalytic activities and very high selectivities for flavanones were obtained in solvent-free reactions. The influence of the substituting groups in the aromatic rings of benzaldehyde and 2′-hydroxyacetophenone was investigated under solvent-free conditions. The influence of electron-donating and electron-withdrawing groups at the para position of benzaldehyde was contrary to the results obtained over other base catalysts. The possible reaction mechanism involving the formation of imine intermediates was suggested for the synthesis of flavanone over aminopropylated silica.

Compatibilization of water borne poly(ethylene oxide)‐silica hybrids

AbstractOrganic‐inorganic hybrid materials, incorporating nanostructured silica networks within a poly(ethylene oxide) matrix (PEO), were produced via the sol–gel process from water solution mixtures of poly(ethylene oxide) and prehydrolyzed tetraethylorthosilicate (TEOS) in the presence of a trialkoxysilane compatibilization agent, γ‐glycidyloxypropyltrimethoxysilane (GOTMS). These mixtures were cast into films by evaporating the solvent and finally drying in an air‐circulating oven at 60°C. By varying the composition of the alkoxysilane solution mixture and mixing conditions, different morphologies were obtained, ranging from semi‐interpenetrating networks of PEO within highly cross‐linked siloxane domains, to finely dispersed nanostructured systems exhibiting either co‐continuous or particulate structure. The effects of pH, type of solvents, mixing temperatures and time, as well as the concentration of the compatibilization agent was found to be extremely important in controlling the morphology and properties of the final PEO‐SiO2 hybrid films. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 125–134, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20001