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A series of composites of phosphotungstic acid (PWA) H 3 PW 12 O 40 with SBA-15 were prepared by varying PWA amount from 5% to 30% by one-step sol-gel hydrothermal as well as by impregnation methods. Successful incorporation of PWA into the SBA-15 framework by sol-gel method was confirmed by 31 P NMR in which a shifting of the peak due to tetrahedral ‘P’ atom of PWA from −14.32 and −14.49 ppm was observed. The composites exhibited both Brønsted and Lewis acidity, large and well distributed three dimensional interconnected pores with high surface areas exhibiting excellent activity for one pot synthesis of 5-(hydroxymethyl) furfural (5-HMF) and 5-(ethoxymethyl) furfural (EMF) from fructose. The minimum loading of 5% of PWA in SBA-15, gave 78% fructose conversion with the highest yield of 70% towards 5-HMF. Increase in PWA loading up to 20% resulted in the enhanced fructose conversion of 95% accompanied by further etherification of 5-HMF to 67 and 12% yield towards EMF and ethyl levulinate (EL), respectively. Increasing the % of PWA in SBA-15 matrix resulted in increase in the acidity of the composites giving the yield trend as 5-HMF < EMF < EL. Catalyst prepared by sol-gel method showed excellent recyclability up to 3 reuses. [ABSTRACT FROM AUTHOR]

We investigated the removal of spray paint from heritage granite surfaces using a nanosecond pulse laser and compared the results, in terms of the effectiveness of treatment and preservation of the stone surface from potential damage, with results obtained using a femtosecond pulse laser. We show that, with the nanosecond laser, the ablation threshold of the stone was measured at 0.5 J·cm-2, but it was only possible to remove certain types of spray paints, such as blue and green paints, at a higher fluence of 0.9 J·cm-2. To remove other types of paints, such as red and yellow, it was necessary to increase even further the laser fluence to 1.5 J·cm-2, well above the ablation threshold of the stone. In this case, damage was induced in the minerals, such as melting of biotite, and a general roughening of the other minerals' surfaces was observed. Despite nanosecond pulse lasers being more widespread for cleaning purposes, we demonstrate that femtosecond pulse lasers allowed better effectiveness in removing various colours of paint, without leaving residues, while keeping the laser energy below the damage threshold of the underlying stone, allowing complete preservation of the substrate, and avoiding the melting of the most sensitive mineral grains (particularly biotite). We determined the ablation efficiency of spray paint using the femtosecond pulse laser and found a maximum ablation regime centered around 6.2 J·cm-2, at 8.36 mm3·(min·W)-1. This study highlights the benefits of using a laser with femtosecond pulses instead of longer pulse durations (nanosecond range) for the preservation and maintenance of heritage stone. [ABSTRACT FROM AUTHOR]

• Defined ablation thresholds of four major minerals of granite for fs-laser pulses. • Maximum ablation rate of 0.27 ± 0.03 mm3·(min·W)−1 at a fluence of 8.4 ± 1.0 J·cm−2. • Raman spectra show no structural damage to quartz and feldspar at high fluences. • Morphological damage at crater bed observed on biotite above its ablation threshold. • Safe fluence advised for cleaning/conservation of granite below 1.0 ± 0.1 J·cm−2. This paper investigates the ultrashort pulsed laser ablation of a high heritage value Australian granite comprising quartz, feldspar (plagioclase and minor potassium-feldspar), and Mg-Fe-bearing minerals (biotite and hornblende). This work is relevant to laser cleaning and texturing of heritage stone surfaces and the preparation and maintenance of granite in other applications. The experiments were undertaken in an ambient lab air environment (23 ± 2 °C and 20–40 % relative humidity) with nitrogen blow, on dry surfaces using 275 fs duration laser pulses at 1029 nm. The ablation behaviour of the different granite minerals was experimentally studied in a fluence range of 1– 17 J·cm−2 in the single shot per spot regime and the ablated surfaces were assessed with a multi-analytical approach including optical and scanning electron microscopy, Raman spectroscopy and optical profilometry. The ablation threshold was established for each different mineral in the stone. Biotite is the most readily ablated, with an ablation threshold of 1.1 ± 0.1 J·cm−2. It is followed by hornblende at 1.3 ± 0.1 J·cm−2, plagioclase at 1.4 ± 0.1 J·cm−2 and quartz, at 1.6 ± 0.1 J·cm−2, which is the most resistant component mineral. Following the electrostatic laser ablation model, the ablation thresholds were theoretically estimated for each mineral phase and demonstrated to be in reasonable agreement with the experimental results. The highest ablation efficiency of the granite as a whole was determined to occur at a fluence of 8.4 J·cm−2, giving an ablation efficiency of 0.27 ± 0.03 mm3·(min·W)−1 in terms of volume removal. From the experimental data, a maximum laser fluence for conservation cleaning was determined at 1.0 ± 0.1 J·cm−2, at which no discernible change or detrimental effect on the granite was observable. Above this fluence, morphological changes were induced in the stone and higher fluences should therefore be avoided for conservation cleaning. [ABSTRACT FROM AUTHOR]

• Femtosecond pulse laser cleaning granite of the Sydney Harbour Bridge. • Successful cleaning of biofilm and environmental dirt using femtosecond pulse laser. • Full removal of biofilm in 5 to 7 scans below stone's damage threshold (1.0 J·cm-2). • Complete removal of environmental dirt achieved for 5 laser scans at 1.0 J·cm-2. • No damage induced on minerals confirmed by optical microscopy. We investigated the cleaning of biofilms and general dirt soiling from the granite of the pylons of the iconic Sydney Harbour Bridge using a femtosecond pulse laser. We demonstrated that this laser emitting pulses at 1029 nm was successful to restore the surface of the stone without damaging the sensitive minerals. The effectiveness of the treatment and the effects on the substrate were evaluated using optical microscopy, infrared spectroscopy, and colorimetry. We showed that satisfactory cleaning results can be achieved at a laser energy of 1.0 J·cm-2, below the damage threshold of the stone. Biofilms and environmental soiling were completely removed from the stone surface after five to seven laser scans, and no residues were found after treatment, even at cracks and grain boundaries. This study illustrates the ability of femtosecond pulse lasers to clean heritage stonework without damaging the underlying substrate. [ABSTRACT FROM AUTHOR]

Abstract: A l-proline catalyzed direct diastereoselective 6-enolexo aldolization reaction of differentiating dialdehydes derived from tartaric acid is presented. This organocatalytic approach provides high levels of syn-selectivity (dr >10:1) with the stereocontrolled C–C bond formation between C4 and C5 intramolecularly, which can serve to synthesize imino-sugar skeleton quickly. [ABSTRACT FROM AUTHOR]

Powerful short laser pulse focused on a surface swiftly transforms the solid into the thermally and electrically inhomogeneous conductive plasma with the large temperature and dielectric permeability gradients across the focal spot. The laser-affected spot becomes thermally inhomogeneous with where temperature has maximum in the centre and gradually decreasing to the boundaries of the spot in accord to the spatial intensity distribution of the Gaussian pulse. Here we study the influence of laser polarisation on ionization and absorption of laser radiation in the focal spot. In this paper we would like to discuss new effect in thermally inhomogeneous plasma under the action of imposed high frequency electric field. We demonstrate that high-frequency (HF) electric field is coupled with the temperature gradient generating the additional contribution to the conventional electronic heat flow. The additional heat flow strongly depends on the polarisation of the external field. It appears that effect has maximum when the imposed electric field is collinear to the thermal gradient directed along the radius of a circular focal spot. Therefore, the linear polarised field converts the circular laser affected spot into an oval with the larger oval’s axis parallel to the field direction. We compare the developed theory to the available experiments, discuss the results and future directions. [ABSTRACT FROM AUTHOR]

• Click chemistry. • Azides + aldehydes or ketones. • Triazoles. • Water. A synthetic route for the direct conversion of arylazides into the corresponding trizoles via phase transfer catalyst-assisted [3+2] cycloaddition reaction under basic conditions in aqueous medium is reported. This synthetic methodology, which offers high yields and excellent regioselectivity for varieties of triazoles at 100 °C for 24 h–48 h and this 'greener' synthesis constitutes an alternative to the previously reported well established click reactions. [ABSTRACT FROM AUTHOR]

Biomass being a renewable source of energy, has emerged as an attractive target for manufacturing valuable products. These possibilities can be explored to meet the current need for degradable plastic, 2,5-furandicarboxylic acid (FDCA). Integration of chemical and biological approaches for direct biomass conversion into FDCA was evaluated in this study. 5-hydroxymethylfurfural (5-HMF) was chemo-catalytically obtained from fructose using recyclable amberlyte IR-120 as a catalyst with >98% purity. Klebsiella oxytoca NCIM 2694 bacterial strain showed the potential of converting 98% of 5-HMF into FDCA with 58% selectivity at 96 h. With optimized conditions of pH 7, 37 °C, 2 g whole cells, we reported 99% 5-HMF conversion to FDCA with 95% selectivity at 72 h and 2667 mg L−1 yield, with 39 mg L−1 h−1 productivity. This is the highest yield obtained with the substrate concentration as high as 3000 mg L−1 reported till date. While the bacterial tolerance to 5-HMF observed was for the highest 5-HMF concentration of 4000 mg L−1, with 99% conversion however, compromising the FDCA yield to 2447 mg L−1 and 32 mg L−1 h−1 productivity. Atom economy of 85% and E factor of 17.71 g g−1 was obtained as a measure of its efficiency and sustainability of the process. The developed process will decrease the cost by excluding any extra nutrient supplement, complete substrate utilization, highest FDCA selectivity/productivity and higher tolerance by K. oxytoca, sequentially catalyzing the oxidations by a single route for FDCA synthesis from renewables. [Display omitted] A versatile renewable building block, 5-hydroxymethylfurfural, acts as a bridge between biomass and biochemical synthesis by a cost-effective process. • A sustainable and greener approach by combining chemocatalytic and biocatalytic process. • 5-HMF, chemo-catalytically obtained from fructose using a recyclable catalyst with >98% purity. • Klebsiella oxytoca NCIM 2694 completely utilized the crude 5-HMF for FDCA production (95%). • The strain also showed improved substrate tolerance with 4000 mg L−1 5-HMF. • No supplementation of additional nutrients for the organism. [ABSTRACT FROM AUTHOR]

Abstract: Nano-structured, spinel Co3O4 catalyst was developed for the aqueous phase oxidation of veratryl alcohol, which showed the highest conversion of 85% with 96% selectivity to veratryl aldehyde. The co-existence of Co3+ and Co2+ species in the octahedral and tetrahedral positions respectively, was confirmed by XPS, cyclic voltammogram, TPR and TPO characterization. The rod-like morphology of Co3O4 catalyst was confirmed by HRTEM. The effects of various reaction parameters namely, catalyst concentration, temperature and partial oxygen pressure on conversion and selectivity patterns were also studied for the oxidation of veratryl alcohol. This catalyst also showed an excellent stability as evidenced by successful reusability for three times. [Copyright &y& Elsevier]

Abstract: The intramolecular alkyne–azide Huisgen [3+2] cycloaddition reaction as a ‘click-chemistry’ reaction without a metal catalyst has been studied under aerobic conditions. The synthesis of various pyrrolidine–triazole hybrid compounds has also been achieved by using this intramolecular cycloaddition reaction in water with complete 1,5-regioselectivity. [Copyright &y& Elsevier]

Abstract: Activities of graphite-supported rhodium catalysts were examined for the hydrogenation of naphthalene in supercritical carbon dioxide (scCO2) solvent at 313K, and results were compared with those of activated carbon-supported rhodium catalysts. The graphite-supported rhodium catalysts exhibited higher activities on a catalyst-weight basis and higher turnover frequency values for the naphthalene hydrogenation in scCO2 than activated carbon-supported rhodium ones. [Copyright &y& Elsevier]

Abstract: The synthesis of capped α-Fe2O3 nanoparticles from thermal treatment of iron (III) hydroxy-oleate in boiling organic solvents around 250°C with retention of the integrity of the oleate units during the reaction process is reported. The formation of capped iron oxide particles is accomplished under aerobic conditions while the solvents used in the synthesis have strong influence on the nature and morphology of nanoparticles. These nanoparticles are studied by means of X-ray powder diffraction, IR and XPS while the morphology and particle size of nanocrystals are evaluated using SEM and TEM analysis suggesting the formation of monocrystalline α-Fe2O3 particles having cubical and spherical morphologies with sizes ranging from 20 to 30nm. This organophilic material with oleate capping around the surfaces can be readily dispersed in organic solvents thus forming organosols. These organosols exhibit band-edge emission photoluminescence band both in toluene as well as in solid state while FT-IR analysis reveals formation oleate capped nanoparticles The XPS data indicate ferric state having doublet from Fe 2p3/2 and Fe 2p1/2 core-level electrons. [Copyright &y& Elsevier]

Abstract: The wavelength dispersion of the Verdet constants of bulk As–S, As–Se–S, Ge–As–Se and Ga–La–S-based chalcogenide glasses has been investigated at wavelengths between 675 and 1550nm. Ge33As12Se55 was found to have the highest Verdet constant, 0.0485min/G.cm at 1550nm, 30 times that of silica. The high Verdet constant of Ge33As12Se55 is related to its smaller band gap energy compared with the other glasses. Further improvement of the Verdet constants of the Ge–Se-based chalcogenide glasses by engineering their compositions could make them promising materials for integrated magneto-optical devices. [Copyright &y& Elsevier]

We prepared a series of alkali (Na and K) and alkaline earth metal (Ca and Ba) promoted Co/CeO 2 catalysts to investigate the effect of the promoter on the catalytic performance of the catalyst in the high-temperature water-gas shift (WGS) reaction of waste derived synthesis gas. Interestingly, alkali metal promoted catalysts deactivated rapidly compared to alkaline earth metal promoted catalysts. Alkaline earth metal promoted catalysts showed relatively higher stability (> 50 h) even at a very high gas hourly space velocity of 143,000 h −1 . X − ray diffraction (XRD) and transmission electron microscopy (TEM) results reveal that the higher stability of the alkaline earth metal promoted catalysts was due to the strong resistance to sintering, showing a relatively small crystallite size of metallic cobalt compared to the alkali metal promoted catalysts after WGS reaction. [ABSTRACT FROM AUTHOR]

Abstract: Sn-MFI/MCM-41 composite material was successfully synthesized by monitoring the re-crystallization time in a simple two-step crystallization process. The length of period allowed for the recrystallization of the precursor species was found to be a controlling factor to achieve either the end members viz. Sn-MCM-41 and Sn-MFI or Sn-MFI/MCM-41 composite material. Powder XRD, FTIR, SEM, TEM, nitrogen sorption measurement, DRUV–vis and hydroxyalkylation of p-cresol reaction were used as the characterization tools. Attempts were also made to establish the relationship between type of phase formed and the process parameters such as aging time, re-crystallization temperature, time and molar ratios of TPAOH/SiO2, CTMABr/SiO2 and SiO2/SnO2 in the gel. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of a new class of hybrid 1,2,3-triazozlo-δ-lactams/lactones has been achieved using the Huisgen [3+2] dipolar cycloaddition ‘click-chemistry’ reaction of various organic azides with an activated alkyne in water, followed by cyclization. [Copyright &y& Elsevier]

Abstract: Hydrogenation of 4-alkylphenols was studied over a carbon-supported rhodium catalyst in supercritical carbon dioxide (scCO2) solvent, and the results were compared with those in 2-propanol. Higher selectivities to cis-4-alkylcyclohexanols were obtained in scCO2 than in 2-propanol for the hydrogenation of all 4-alkylphenols tested. In addition, the formation of alkylcyclohexane (dehydroxylated product) was suppressed in scCO2. Stereoselectivities to cis forms were further improved in the presence of hydrochloric acid. [Copyright &y& Elsevier]

Abstract: Formation of three-dimensional (3D) patterns of 0.2–0.5μm diameter voids inside a transparent solid has been demonstrated. The nano-voids could be created with a spacing ∼2μm thus suggesting the possibility of permanent 3D optical memory with density ∼100Gbit/cm3. Extremely high pressures of ∼10TPa and temperatures up to 105 K can be produced by a single sub-picosecond laser pulse tightly focused inside transparent dielectrics. Analysis of the size of the void and the shock affected zone as a function of the deposited energy shows that the experimental results can be explicitly understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Therefore, the size of the void can be controlled and predicted by proper focusing conditions and laser parameters. [Copyright &y& Elsevier]

Abstract: We report on a three-dimensional single-shot optical recording by 150fs pulses at 800nm wavelength in Fe-doped and stoichiometric undoped LiNbO3. The highest refractive index modulation of ∼10−3 per single pulse has been achieved at close to the dielectric breakdown irradiance of ∼TW/cm2, and was found to be independent of polarization of the writing beam. The quasi-permanent and rewritable bits have been demonstrated in Fe-doped LiNbO3. Recording in undoped stoichiometric LiNbO3 was of transient nature with full optical contrast recovery on a 0.1–1s scale. The observed refractive index modulation is explainable by the photovoltaic effect in LiNbO3. [Copyright &y& Elsevier]