Abstract  Continuous, on-site monitoring of personal exposure levels to occupational chemical hazards in ambient air is a long-standing analytical challenge. Such monitoring is required to institute appropriate health measures but is often limited by the time delays associated with batch air sampling and the need for off-site instrumental analyses. In this work, we report on the first attempt to use the catalytic properties of perfluorosulfonic acid (PSA) membranes to obtain a rapid, selective, and highly sensitive optical response to trimellitic anhydride (TMA) in the gas phase for portable sensor device application. TMA is used as starting material for various organic products and is recognized to be an extremely toxic agent by the National Institute for Occupational Safety and Health (NIOSH). Resorcinol dye is shown to become immobilized in PSA membranes and diffusionally constrain an orange brown product that results from acid-catalyzed reaction with more rapidly diffusing TMA molecules. FTIR, UV/vis, reaction selectivity to TMA versus trimellitic acid (TMLA), and homogeneous synthesis are used to infer 5,7- dihydroxyanthraquinone-2-carboxylic acid as the acylation product of the reaction. The color response has a sensitivity to at least 3 parts per billion (ppb) TMA exposure and, in addition to TMLA, excludes maleic anhydride (MA) and phthalic anhydride (PA). Solvent extraction at long times is used to determine that the resorcinol extinction coefficient in 1100 EW PSA membrane has a value of 1210 m(2)/g at 271.01 nm versus a value of 2010 m(2)/g at 275.22 nm in 50 vol% ethanol/water solution. The hypsochromic wavelength shift and reduced extinction coefficient suggest that the polar perfluorosulfonic acid groups in the membrane provide the thermodynamic driving force for diffusion and immobilization. At a resorcinol concentration of 0.376 g/L in the membrane, a partition coefficient of nearly unity is obtained between the membrane and solution concentrations and a maximum conversion rate of one ambient TMA molecule for every two membrane-immobilized resorcinol molecules is observed in 15 min.

Abstract  This study assesses the potential of ozonation and advanced oxidation process O(3)/H(2)O(2) to enhance the dimethyldisulfide (DMDS) mass transfer in a compact chemical scrubber developed for air treatment applications. Theoretical calculations, through Hatta number and enhancement factor evaluations for two parallel irreversible reactions, were compared to experimental data and enabled the description of the mass transfer mechanisms. These calculations required the determination of the kinetic constant of the DMDS oxidation by molecular ozone ( [Formula: see text] ) and the measurement of the hydroxyl radical concentration within the scrubber. The competitive kinetic method using the 1,2-dihydroxybenzene (resorcinol) enabled to determine a value of the kinetic constant [Formula: see text] of 1.1×10(6)M(-1)s(-1) at 293K. Then, experiments using para-chlorobenzoic acid in solution allowed measuring the average hydroxyl concentration in the scrubber between the inlet and the outlet depending on the chemical conditions (pH and inlet O(3) and H(2)O(2) concentrations). High hydroxyl radical concentrations (10(-8)M) and ratio of the HO°-to-O(3) exposure (R(ct)≈10(-4)) were put in evidence.

Abstract  All-carbon-based carbon nanotube (CNT)/microporous carbon core-shell nanocomposites, in which a CNT as the core and high-surface-area microporous carbon as the shell, have been prepared by in situ resorcinol-formaldehyde resin coating of CNTs, followed by carbonization and controlled KOH activation. The obtained nanocomposites have very high Brunauer-Emmett-Teller surface areas (up to 1700 m(2)/g), narrow pore size distribution (<2 nm), and 1D tubular structure within a 3D entangled network. The thickness of the microporous carbon shell can be easily tuned from 20 to 215 nm by changing the carbon precursor/CNT mass ratio. In such a unique core-shell structure, the CNT core could mitigate the key issue related to the low electronic conductivity of microporous carbons. On the other hand, the 1D tubular structure with a short pore-pathway micropore as well as a 3D entangled network could increase the utilization degree of the overall porosity and improve the electrode kinetics. Thus, these CNT/microporous carbon core-shell nanocomposites exhibit a great potential as an electrode material for supercapacitors, which could deliver high specific capacitance of 237 F/g, excellent rate performance with 75% maintenance from 0.1 to 50 A/g, and high cyclability in H2SO4 electrolyte. Moreover, the precisely controlled microporous carbon shells may allow them to serve as excellent model systems for microporous carbons, in general, to illustrate the role of the pore length on the diffusion and kinetics inside the micropores.

Abstract  The influence of ligand binding and conformation state on the thermostability of hexameric zinc-insulin was studied by differential scanning calorimetry (DSC). The insulin hexamer exists in equilibrium between the forms T6, T3R3, and R6. Phenolic ligands induce and stabilize the T3R3- and R6-states which are further stabilized by binding of certain anions that do not stabilize the T6-state. It was shown that the thermostability of the resorcinol-stabilized R6-state was significantly higher than that of the T6-state. Further analysis showed that phenol- and m-cresol-stabilized R6-hexamer loses three ligands before reaching the unfolding temperature and hence unfolds from the T3R3-state. The relative affinity of the four tested anionic ligands was found, by DSC, to be thiocyanate > or = 4-hydroxy-3-nitrobenzoate > p-aminobenzoate > chloride. The results correlate with other methods and demonstrate that DSC provides a general and useful method of evaluation of both phenolic and anionic ligand binding to insulin without the use of probes or other alterations of the system of interest. However, it is a prerequisite that the binding is strong enough to saturate the binding sites at temperatures around the unfolding transition.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. We recently reported on the ability of a microbial consortium eluted from dioxin-contaminated Passaic River sediments to dechlorinate polychlorinated dibenzo-p-dioxins (PCDDs) through peridechlorination of 2,3,7,8-substituted hepta- to penta-CDDs resulting in the transient production of 2,3,7,8-tetra-CDD and through perilateral dechlorination pathway of non-2,3,7,8-substituted congeners. The dechlorination of PCDDs under combined reductive activities of the same microbial community and model humic constituents (MHCs) (resorcinol, 3,4-dihydroxybenzoic acid (3,4-DHBA), and catechol) was investigated. Model humic constituents alone caused reductive dechlorination of PCDDs, resulting in the production of hepta-, hexa-, and tetra-CDD congeners. Whereas abiotic MHC-stimulated dechlorination ceased at the tetra-CDD group of congeners, microbial activity caused further dechlorination to tri-, di-, and mono-CDDs. Combined with the microbial community, MHCs effected the appearanc

Abstract  In this work, uranyl ion-imprinted resin based on 2-(((4-hydroxyphenyl)amino)methyl)phenol was synthesized by condensation polymerization of its uranyl complex in presence of resorcinol and formaldehyde cross-linkers. Numerous instrumental techniques including elemental analysis, Fourier transform infrared spectroscopy, ultraviolet, (1) H along with (13) C nuclear magnetic resonance spectroscopy have been employed for complete characterization of the synthesized ligand and its uranyl complex. Additionally, the obtained ion-imprinted and non-imprinted resins were investigated using scanning electron microscope and Fourier transform infrared spectroscopy. The effects of various essential parameters such as pH, temperature and contact time on removal of uranyl ions have been examined, and the results indicated that the obtained resin exhibited the optimum activity at pH 5. Furthermore, the adsorption process was spontaneous at all studied temperatures and followed the second-order kinetics model. Also, Langmuir adsorption isotherm exhibited the best fit with the experimental results with maximum adsorption capacity 139.3 mg/g. Moreover, the selectivity studies revealed that the ion-imprinted resin exhibited an obvious affinity toward the uranyl ions in presence of other metal ions compared with the non-imprinted resin.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. A method for the on-line preconcentration and chromatography of trace metals, e.g., Co, Ni, Cu, Zn, Cd and Pb, on N,N,N',N'-tera(2-aminoethyl)ethylenediamine-bonded silica is described. The preconcentrated metals were desorbed with 0.13 M tartrate, which allows direct separation on a cation-exchange chromatographic column. The metals separated were detected by postcolumn reaction with 4-(2-pyridylazo)resorcinol and measuring the absorbances at 500 nm. Linear calibrations graphs were obtained ove the range 1ynthesis and characteristics of the chelated silica are described. The method was applied to the analysis of river and interstitial sediment waters.

Abstract  Sn/C composites were prepared by hydrothermal treatment from a mixture of tin tetrachloride pentahydrate (SnCl4 x 5H2O) and resorcinol-formaldehyde gel (RF gel). Particle size was controlled by varying initial pH of the mixture, and particle size distribution was very narrow. Scanning electron microscopy (SEM) was utilized to examine surface morphology and particle size. Composition was determined by energy dispersive spectrometer (EDS), and crystallinity of synthesized samples was investigated by XRD and Raman spectroscopy. The electrochemical properties of synthesized samples as anodes for Li-ion batteries were investigated in coin cells. The electrochemical performance as an anode was found to be strongly dependent on particle size.

Abstract  Different carbon aerogels were obtained by carbonization of organic aerogels prepared from the polymerization of resorcinol and formaldehyde using potassium carbonate as catalyst. Various solvents were added to the initial mixture to study their effects on the inter- and intra-primary-particle structure of the carbon aerogels. To carry out this study, various techniques were used, including high-resolution transmission and scanning electron microscopy, mercury porosimetry, mechanical tests, N2 and CO2 adsorption at -196 and 0 degrees C, respectively, and immersion calorimetry into benzene. Variation of the solvent used produced changes in the gelation time of the organic aerogels, which gave rise to variations in the inter- and intra-primary-particle structure of the carbon aerogels obtained. The monolith density of the carbon aerogels ranged from 0.37 to 0.87 g/cm3. Samples with a density higher than 0.61 g/cm3 had micropores and mesopores but no macropores. Macro- and mesoporosity had a monomodal pore size distribution. The elastic modulus showed a scaling relationship with density. In all samples studied, which had a mean micropore width of 0.62-1.06 nm, the surface area obtained by enthalpy of immersion into benzene yielded a realistic value of their total surface area.

Abstract  Resorcinol-formaldehyde aerogels and carbon aerogels of different mesoporosities have been used as templates for preparing bimodal zeolites of mesopores. Samples were thoroughly characterized with X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, N(2) adsorption at 77 K, as well as FT-IR spectroscopy and (29)Si nuclear magnetic resonance spectroscopy. The mesoporous ZSM-5 zeolites have additional mesopores of 9-25 nm in widths and 0.07-0.2 cm(3)/g in volumes, besides their perfect inherent micropores. Experimental results show the mesoporous systems of the finally obtained zeolites can be influenced by proper preparation of resorcinol-formaldehyde aerogels and carbon aerogels through solution chemistry. Consequently, zeolites of tunable mesoporosities can be prepared with this unique methodology.

Abstract  A new, rod-shaped, Gram-negative, non-sporing sulfate reducer (strain Ani1) was enriched and isolated from marine sediment with aniline as sole electron donor and carbon source. The strain degraded aniline completely to CO2 and NH3 with stoichiometric reduction of sulfate to sulfide. Strain Ani1 also degraded aminobenzoates and further aromatic and aliphatic compounds. The strain grew in sulfide-reduced mineral medium supplemented only with vitamin B12 and thiamine. Cells contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P582, but no desulfoviridin. Strain Ani1 is described as a new species of the genus Desulfobacterium D. anilini. Marine enrichments with the three dihydroxybenzene isomers led to three different strains of sulfate-reducing bacteria; each of them could grow only with the isomer used for enrichment. Two strains isolated with catechol (strain Cat2) or resorcinol (strain Re10) were studied in detail. Both strains oxidized their substrates completely to CO2, and contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P 582. Desulfoviridin was not present. Whereas the rod-shaped catechol oxidizer (strain Cat2) was able to grow on 18 aromatic compounds and several aliphatic substrates, the coccoid resorcinol-degrading bacterium (strain Re10) utilized only resorcinol, 2,4-dihydroxybenzoate and 1,3-cyclohexanedion. These strains could not be affiliated with existing species of sulfate-reducing bacteria. A further coccoid sulfate-reducing bacterium (strain Hy5) was isolated with hydroquinone and identified as a subspecies of Desulfococcus multivorans. Most-probable-number enumerations with catechol, phenol, and resorcinol showed relatively large numbers (10(4)-10(6) per ml) of aryl compound-degrading sulfate reducers in marine sediment samples.

Abstract  Vertical replication for TEM is ideal for studying non-periodic specimens from 0.7 to 3 nm, a resolution mid-range difficult to attain by any other technique. This paper discusses the importance of vertical replication, its methods and hardware for high-resolution TEM. Evidence from diverse published research will demonstrate vertical replication's versatility in imaging the molecular level normally unattainable in freeze-dried polymers, polyethylene tribological wear on surfaces, low-density polymer networks or biological gels. Vertical platinum-carbon (Pt-C) replication minimizes the horizontal movement of Pt-C on a surface. Surface objects are symmetrically enlarged by a vertically deposited Pt-C film. To estimate real size in replicas, 16-25 particles or filaments need to be measured in calibrated transmission electron microscopy (TEM) images and reduced by a value less than the Pt-C film thickness measured with a quartz monitor. Continuous, vertically deposited Pt-C films are formed on mica at a deposition thickness of around 1.0 nm and on silver at a thickness of 0.4-0.5 nm. The distance between helical turns in poly(1-tetradecene sulfone) of 0.7 nm is the highest resolution achieved with vertical replication. Two polysulfones freeze-dried and vertically replicated on mica contained structures are predicted by indirect physical chemical methods to be present in solution. Polymer chains are fully Pt-C coated, with no uncoated gaps along chains. Some side-chains on the extended non-helical poly(1-tetradecene sulfone) are also detected. To estimate the real chain width, polymer chains measured in images are reduced by the Pt-C film thickness minus 0.5 nm. The polymer chain widths estimated from molecular models are in the same range of widths as those measured using the image size correction method. Also, it is possible to distinguish random coil proteins (chain width of around 0.5 nm) from an alpha-helix (chain diameter of about 1 nm) in vertically replicated samples on silver substrates. In the future, subnanometer resolutions below 0.7 nm should be possible. The resolution of vertical replication depends on the thickness of a continuous, amorphous Pt-C film. That thin, continuous 0.4-0.5 nm Pt-C films on silver substrates can be made suggests that a point-to-point resolution limit of around 0.28 nm in TEM may ultimately be approachable with replication.

Abstract  The photocatalytic activity of TiO2 and ZnO in the presence of MnO2, a particulate matter present in natural water and wastewater, has been studied. We found that a trace amount of MnO2 particles deactivated TiO2 photocatalysts, but its effect on the activity of ZnO was negligible. UV-visible diffuse reflectance spectra (DRS) and surface photovoltage spectroscopy (SPS) analysis implied that the interaction of MnO2 with TiO2 and ZnO could change the energetics of these two photocatalysts. (C) 2007 Elsevier B.V. All rights reserved.

Abstract  Bioadhesives have been used in surgery as hemostatic and wound healing agents. GRF (gelatin + resorcinol + formaldehyde) glue, composed of a mixture of gelatin and resorcinol polymerized by the addition of formaldehyde, has been used for this purpose. Widespread acceptance of the GRF glue, however, has been limited by reports of cytotoxicity due to its release of formaldehyde upon degradation. It has been suggested by Wertzel et al, that the cytotoxicity problem of GRF glue may be overcome by changing its cross-linking method. The study was, therefore, undertaken to assess the feasibility of using a water-soluble carbodiimide or genipin to cross-link gelatin as new bioadhesives to close skin wound lesions in a rat model. Formaldehyde-cross-linked counterpart (GRF glue) and a resorbable suture were used as controls. It was noted that the tensile strength of the skin across each wound treated by either application of test glues or suture increased consistently with time during the healing process. Also, the wounds repaired by test glues or suture caused no calcification. The suture used in the study was completely resorbed at the wound area in about 6 days postoperatively. However, the durations required to completely resorb the carbodiimide- or genipin-cross-linked glues were approximately the same (9 days), while it took about 14 days to completely resorb the formaldehyde-cross-linked glue. The healing process for the suture wound repaired was more rapid than those treated by test glues. Of the test glues, the wounds treated by the carbodiimide- or genipin-cross-linked glues induced less inflammatory response and recovered sooner than that treated by the formaldehyde-cross-linked glue. This indicated that the biocompatibility of the carbodiimide- or genipin-cross-linked glues was superior to the formaldehyde-cross-linked glue. The results of this study may serve as a preliminary experimental model for the further investigation of both the carbodiimide- and genipin-cross-linked glues when applied to human skin closure.

Abstract  Carbon cryogels (CCG) with controlled porous size were developed for enzyme electrode. CCGs were prepared by sol-gel polycondensation of resorcinol and formaldehyde using CO(3)(2-) as a catalyst. The average pore radius range from 5 to 40 nm was controlled by changing the mole ratio of resorcinol to the catalyst. Fructose dehydrogenase adsorbed on a CCG electrode exhibited large catalytic currents for fructose oxidation without redox mediators. The catalytic current depended on the pore size. The catalytic current density was quite low when the pore size of CCG was small compared with the size of FDH. On the other hand, the wider pore resulted in higher catalytic current density was observed under the experimental conditions. It is assumed that caged enzymes embedded in the carbon mesopore are apt to communicate with the electrode directly. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  New synthesis conditions to rapidly fabricate monolithic carbon aerogels based on resorcinol and formaldehyde were developed using ambient pressure drying. The resorcinol-formaldehyde aerogel network synthesized under strong basic conditions not only dramatically reduced the gelation time but also exhibited better particle connectivity. This also allowed for the rapid drying of the wet-gels and subsequent carbonization in an inert atmosphere to yield carbon aerogels. Monolithic carbon aerogels possessing both microporous and macroporous characteristics were synthesized. It was shown that the microstructure of the carbon aerogels was comprised of spherical particles that could be tailored by control of sol-gel preparation parameters, such as volume ratios of formaldehyde, deionized water and ammonium hydroxide with the resorcinol. The synthesized carbon aerogels had a tapping density as low as 0.11 g/cm(3) and a specific surface area as high as 551 m(2)/g.

Abstract  By using a nontargeted GC-MS approach, 153 individual volatile compounds were found in extracts from untoasted, light toasted and medium-toasted cherry, chestnut, false acacia, as well as European and American ash wood, used in cooperage for aging wines, spirits and other beverages. In all wood types, the toasting provoked a progressive increase in carbohydrate derivatives, lactones and lignin constituents, along with a variety of other components, thus increasing the quantitative differences among species with the toasting intensity. The qualitative differences in the volatile profiles allow for identifying woods from cherry (being p-anisylalcohol, p-anisylaldehyde, p-anisylacetone, methyl benzoate and benzyl salicylate detected only in this wood), chestnut (cis and trans whisky lactone) and false acacia (resorcinol, 3,4-dimethoxyphenol, 2,4-dihydroxy benzaldehyde, 2,4-dihydroxyacetophenone, 2,4-dihydroxypropiophenone and 2,4-dihydroxy-3-methoxyacetophenone), but not those from ash, because of the fact that all compounds present in this wood are detected in at least one other. However, the quantitative differences can be clearly used to identify toasted ash wood, with tyrosol being most prominent, but 2-furanmethanol, 3- and 4-ethylcyclotene, α-methylcrotonolactone, solerone, catechol, 3-methylcatechol and 3-hydroxybenzaldehyde as well. Regarding oak wood, its qualitative volatile profile could be enough to distinguish it from cherry and acacia woods, and the quantitative differences from chestnut (vanillyl ethyl ether, isoacetovanillone, butirovanillone, 1-(5-methyl-2-furyl)-2-propanone and 4-hydroxy-5,6-dihydro-(2H)-pyran-2-one) and ash toasted woods. Copyright © 2014 John Wiley & Sons, Ltd.