Some selected fluids have been assessed for their suitability as alternatives to HCFC-22 for air conditioners. Only those refrigerants with zero ozone depletion potential are considered. NIST CYCLE_D has been used for the comparative thermodynamic analysis. Among the refrigerants studied (HFC-134a, HC-290, R-407C, R-410A, and three blends of HFC-32, HFC-134a and HFC-125), HFC-134a offers the highest COP, but its capacity is the lowest and requires much larger compressors. The characteristics of HC-290 are very close to those of HCFC-22, and compressors require very little modification. Therefore, HC-290 is a potential candidate provided the risk concerns are mitigated as had been accomplished for refrigerators. For retrofitting, R-407C is probably the best candidate.

The hydrogen evolution reaction (HER) as a fundamental process in electrocatalysis plays a significant role in clean energy technologies. For an energy-efficient HER, it demands an effective, durable, and low-cost catalyst to trigger proton reduction with minimal overpotential and fast kinetics. Here, we successfully fabricate a highly efficient HER catalyst of N-C/Co/Mo2C holey nanorods with Co/β-Mo2C nanoparticles uniformly embedded in nitrogen-doped carbon (N-C/Co/Mo2C) by pyrolyzing the molybdate-coordinated zeolitic imidazolate framework (ZIF-67/MoO42−) holey nanorods, which result from the reaction between CoMoO4 and MeIM in a methanol/water/triethylamine mixed solution. The uniform distribution of MoO42− in the ZIF-67/MoO42− enables Co/β-Mo2C nanoparticles to be well-distributed within nitrogen-doped carbon holey nanorods. This synthetic strategy endows the N-C/Co/Mo2C catalyst with uniformly decorated bimetal, thus attaining excellent HER electrocatalytic activities with a small overpotential of 142.0 mV at 10 mA cm−2 and superior stability in 1.0 mol L−1 KOH aqueous solution.

A micromechanical model is presented that predicts the stiffness of wood tissues in their three principal anatomical directions, across various hardwood species. The wood polymers cellulose, hemicellulose, and lignin, common to all wood tissues, serve as the starting point. In seven homogenisation steps, the stiffnesses of these polymers are linked to the macroscopic stiffness. The good agreement of model predictions and corresponding experimental data for ten different European and tropical species confirms the functionality and accuracy of the model.The model enables investigating the influence of individual microstructural features on the overall stiffness. This is exploited to elucidate the mechanical effects of vessels and ray cells. Vessels are shown to reduce the stiffness of wood at constant overall density. This supports that a trade-off exists between the hydraulic efficiency and the mechanical support in relation to the anatomical design of wood. Ray cells are shown to act as reinforcing elements in the radial direction.

Mechanochemistry is a branch of solid state chemistry which describes processes that proceed in the solid form upon the application of mechanical energy. At present, mechanochemistry appears to be a science with a sound theoretical foundation which exhibits a wide range of potential applications. Amongst the potential viable processes we can mention the modification of properties of building a wide range of nanomaterials, the new method of nano material production, the activity enhancement and regeneration of catalysts, the new method of modification of solubility and bioavailability of nano drugs in pharmacy, the control of reaction kinetics in the chemical technology and finally the recent achievements in the synthesis of nano advanced materials.Mechanochemical methods may be used to enhance traditional laboratory techniques. Through making use of activation, quite a number of chemical ameliorations had been performed. Thereby improving many present protocols with superior effects in comparison to reactions achieved under conventional situations. The purpose of this chapter is to evaluate and focus on the recent advances mechanochemical synthesis of nanomaterials.

The recovery of purified fractions of vanillin and syringaldehyde (V&S) from an oxidized lignin medium has attracted considerable attention driven by the high added value of these products and the importance of lignin valorization processes in biorefineries. Polymeric resins with high specific area can be a viable option for the adsorption of aromatic compounds in polar solvents and desorption with less polar solvents for their recovery.In this work, mono-component batch and fixed bed adsorption experiments were performed with V&S on Sepabeads SP700 in ethanol:water (90:10, % V/V) solutions to obtain the respective isotherm models at 298 K and 313 K. The adsorption behaviors of V&S were described by Linear and Freundlich models.On the perspective of the real application of Sepabeads SP700 for recovery of V&S, fixed bed was first loaded with an aqueous solution of each compound and then desorption was performed with ethanol:water (90:10, % V/V). More than 84% of each compound was readily desorbed within 6 bed volumes, yielding concentration factors between 19-fold and 67-fold, relative to the inlet feed concentration.The desorption histories at the outlet of the fixed bed were successfully described by the mathematical model comprising the equilibrium isotherms and linear driving force rate equations to describe the diffusional mass transfer inside the resin.This work demonstrates that the adsorption of V&S from aqueous solution into Sepabeads SP700 bed and desorption with ethanol:water (90:10, % V/V) solution is a promising approach for the recovery of these compounds from lignin oxidation mixture. The high level of concentration achieved with this strategy and the type of solvent used is favorable for any further processing step, such as crystallization or spray drying.

A microwave-enhanced advanced hydrogen peroxide oxidation process (MW/H2O2-AOP) was studied in order to investigate the synergetic effects of MW irradiation on H2O2 treated waste activated sludges (WAS) in terms of mineralization (permanent stabilization), sludge disintegration/solubilization, and subsequent anaerobic biodegradation as well as dewaterability after digestion. Thickened WAS sample pretreated with 1 g H2O2/g total solids (TS) lost 11–34% of its TS, total chemical oxygen demand (COD) and total biopolymers (humic acids, proteins and sugars) via advanced oxidation. In a temperature range of 60–120 °C, elevated MW temperatures (>80 °C) further increased the decomposition of H2O2 into OH• radicals and enhanced both oxidation of COD and solubilization of particulate COD (>0.45 micron) of WAS indicating that a synergetic effect was observed when both H2O2 and MW treatments were combined. However, at all temperatures tested, MW/H2O2 treated samples had lower first-order mesophilic (33 ± 2 °C) biodegradation rate constants and ultimate (after 32 days of digestion) methane yields (mL per gram sample) compared to control and MW irradiated WAS samples, indicating that synergistically (MW/H2O2-AOP) generated soluble organics were slower to biodegrade or more refractory than those generated during MW irradiation.

Current study deals with the production of cellulases and xylanases from the Rhizopus oryzae SN5 isolated from composed soil of Himalayan pine forest, in order to meet the challenges of lignocellulosic biomass based biorefineries. Culture parameters for concomitant production of cellulase and xylanase were optimized through EVOP-factorial design technique under solid state fermentation. And maximum yield of cellulase and xylanase were obtained 437.54 U/gds and 273.83 U/gds, respectively at 30 °C and pH 6.0 after 5 days of incubation. On applying these enzymes for the saccharification of the dilute acid pretreated Sorghum Stover (SS), 0.407 g/g sugar was yielded. This hydrolysate on fermentation, yielded 0.411 g/g ehanol with Saccharomyces cerevisiae (NCIM 3288), which could be considered a good conversion. Therefore, Rhizopus oryzae SN5 was found as potent strain for the production of the cocktail of lignocellulosic biomasss hydrolytic enzymes and would be promising tool in the area of lignocellulose based bio-refineries.

Gold clusters supported on titanium silicalite-1 (hereafter denoted as Au/TS-1) with high gold loading at ∼0.1–0.16 wt%, prepared by the deposition precipitation (DP) method, showed about two times enhancement in the PO rate (∼300versus∼150gPOh-1kgCat-1 at 200 °C), ∼10% increase in PO selectivity (∼80% versus ∼70%) and ∼5–10% increase in H2 selectivity (∼20% versus ∼10%) when Cs2CO3 instead of Na2CO3 was used as the precipitation agent. Using Cs2CO3 as the precipitation agent caused a fourfold increase in Au uptake efficiency, indicating a strong interaction between Cs and Au in the Au/TS-1 system. XPS/TEM analyses for two Au/TS-1 samples with the same gold loading at ∼0.16 wt% but different alkali metals (Cs versus Na) indicate that more Au was retained inside the TS-1 nanopores for the Cs sample. The presence of Cs is, therefore, proposed to help stabilize small gold clusters (<1 nm) inside the TS-1 nanoporous channels at the high gold loading (>0.1 wt%) due to the Cs/Au interaction, resulting in the promotion of PO rate per gram of catalyst. Furthermore, similar apparent activation energy at ∼30 kJ mole−1 observed for the Au/TS-1 catalysts with the presence of either Cs or Na suggests that the number, but not the nature of the active sites, is changed in the Cs-promoted samples. Finally, regardless of the type of alkali metal (Na or Cs) present in the catalysts, lower Ti content (Si/Ti molar ratio ∼100) for Au/TS-1 catalysts was found to favor PO catalytic performance.

In this paper we present a quantitative model for comparing university departments concerned with the same discipline. This model is based upon ideas drawn from data envelopment analysis. Computational results are given for chemistry and physics departments in the United Kingdom.

The dichloromethane extract from the leaves of Caesalpinia platyloba provided cassane diterpenes whose structures were determined as (−)-(5S,6R,8S,9S,10R,14R)-6-acetoxyvouacapane (1), (−)-(5S,6R,8S,9S,10R,12Z,14R)-6-acetoxycassa-12,15-diene (3), and (−)-(5S,6R,8S,9S,10R,13E)-6-acetoxycassa-13,15-diene (4). Compound 1 was chemically correlated with (−)-(5S,6R,8S,9S,10R,14R)-6-hydroxyvouacapane (2), (+)-(5S,8S,9S,10R,14R)-6-oxovouacapane (5), and (+)-(5S,6S,8S,9S,10R,14R)-6-acetoxyvouacapane (6), the last one previously isolated from Dipteryx lacunifera. The absolute configurations of all six diterpenes 1–6 were established by comparison of DFT calculated vibrational circular dicroism spectra of 1, 2 and 5 with those obtained experimentally. In addition, several reported chemical shifts for 2 and 5 were reassigned based on two-dimensional NMR measurements.

Diols are chemicals with two hydroxyl groups which have a wide range of appealing applications as chemicals and fuels. In particular, four diol compounds, namely 1,3-propanediol (1,3-PDO), 1,2-propanediol (1,2-PDO), 2,3-butanediol (2,3-BDO) and 1,4-butanediol (1,4-BDO) can be biotechnologically produced by direct microbial bioconversion of renewable materials. These diols are considered as platform green chemicals. We review and discuss here the recent development in the microbial production of these diols, especially regarding the engineering of production strains and optimization of the fermentation processes.

Green Chemistry is a design philosophy that aims to reduce or eliminate negative environmental impacts resulting from the production and use of chemicals. Microchannel process technology offers process intensification, in the form of enhanced heat and mass transfer, to a wide range of chemical reactions. This paper describes how the application of microchannel technology can help producers achieve the goals of Green Chemistry and minimize the environmental consequences of chemical and fuel production. The examples used to illustrate these advantages are Velocys’ Fischer-Tropsch synthesis for biomass-to-liquids, DSM and Karlsruhe collaboration for fine chemical production, and Stevens Institute's work in applying microchannels to the production of hydrogen peroxide, as well as a detailed study of how microchannel architecture can minimize pollutant emissions from steam methane reforming.

Tm3+-doped 12CaO·7Al2O3 (C12A7) nanocrystals with the grain size of 360 nm have been fabricated by chemical co-precipitation method. Up-converted emissions at 367, 457, 476, 648, and 682 nm, corresponding to the 1D2 → 3H6, 1D2 → 3F4, 1G4 → 3H6, 1G4 → 3F4, and 3F3 → 3H6 transitions, respectively, are observed under 808 nm excitation. Plasmon-enhanced ultraviolet (UV) and blue upconverted emissions of Tm3+-doped C12A7 nanocrystals have been achieved by attaching Ag nanoparticles onto the surface of nanocrystals. The enhancement of the upconverted emissions is highly wavelength-dependent. The emission intensities of the sample with Ag+ concentration of 5.0 × 10−3 mol/L at 367 and 476 nm are enhanced about 10 and 3 times, respectively, relative to the sample without Ag attachment. The enhancement mechanism can be ascribed to surface plasmon resonance due to the highly localized electric field and the increased radiative decay rate around Ag nanoparticles. Our results suggest that Tm3+-doped C12A7 nanocrystals by attaching Ag nanoparticles might be a potential material for upconversion, compact and tunable short-wavelength lasers.

The Karukéra spur is an easternmost submerged rise of the Lesser Antilles fore-arc in the Guadeloupe archipelago, culminating about 4000 m above the fore-arc basin 150 km west of the deformation front. The analysis of 3500 km 2D high-resolution multichannel seismic reflection and multibeam bathymetric data, and the study of 14 core samples, allow for the first time to reconstruct its sedimentary anatomy and tectonic evolution. Seven seismic units (US1 to US7) are evidenced, organised into four major depositional sequences separated by erosional surfaces. Units US1 to US4 thicken to the south-southeast on the spur. The sedimentary deposits rest upon a deeply eroded metamorphic basement of the Caribbean Plate as in La Désirade Island. Sequence 1 (units US1 and US2) remains unknown in its lower part because it does not outcrop. Its upper part comprises early Miocene shallow water carbonates. Sequence S2 (Unit US3) only comprises an upper Miocene transgressive systems tract deposited into basinal environment. It is bounded by major erosional surfaces SB2 and SB3. Sequence 3 (US4 to US6) is Zanclean to Pleistocene. It is dominantly composed of shallow water, reefal deposits. Sequence 4 corresponds to recent deposits. The Karukéra spur experienced three main extensional episodes with alternations between uplift and subsidence periods. Uplifts are responsible for emersions and erosions. Subsidence severely drowned shallow water deposits. The first extensional episode led to the formation of horsts and grabens in the basement, prior to early Miocene deposits. The second extensional episode occurred during upper Miocene, in accordance with data in surrounding islands. The third tectonic episode developed since Calabrian. Noticeable is the constant reactivation of N130°–N150°, N150°–N180° and N40° trending faults since early Miocene and the neoformation of E–W trending faults since Calabrian. Our results suggest that at the latitude of Guadeloupean archipelago the Lesser Antilles subduction zone is an erosional margin because of the successive sweepings of the Santa Lucia then Tiburon Ridges.

Sasol has been operating the Sasol–Lurgi fixed bed coal gasification process for more than fifty years, and with ninety seven units in operation still remains the world's largest commercial application of this technology. The combined operational and engineering expertise vested in Sasol represents a formidable capability in the field of coal and gasification science. Coal is a crucial feedstock for South Africa's unique synfuels and petrochemicals industry, and is used by Sasol as a feedstock to produce synthesis gas (CO and H2) via the Sasol–Lurgi fixed bed dry bottom gasification process.South Africa, as well as many other countries in the world, will for many years to come rely on its abundant coal resources for energy and specifically for the production of petrochemical products. Synthesis gas production through gasification is growing at a rate of approximately 10% per annum [Office of Fossil Energy, National Energy Technology Laboratory and the Gasification Technologies Council, 2000. Gasification: Worldwide use and acceptance. Contract DE-AMO1-98FE65271], indicating that gasification is definitely not a dying technology. The Sasol plants located in Secunda and Sasolburg (South Africa) gasify > 30 million tons per annum of bituminous coal to synthesis gas, which is converted to fuels and chemicals via the Fischer–Tropsch process. The production of chemicals is currently the dominant application for synthesis gas, followed by power generation, Fischer–Tropsch synthesis and gaseous fuels.Sasol–Lurgi gasifiers are extremely robust devices, and coal from sources with widely varying properties (e.g. ash content < 10% to as high as 35% or “brown coal” with moisture content of approximately 30%) can be gasified provided that certain operational changes are implemented. Other properties, like high caking propensity for example, require blending to acceptable levels and /or mechanical modifications. Interpretation of coal characterization data gives an indication of expected gasifier performance and the suitability of a specific coal source for Sasol–Lurgi Fixed Bed Gasification process. It is therefore critically important to gain an accurate and fundamental understanding of the properties and expected behavior of the targeted coal feedstock in order to (1) prepare a suitable conceptual flow scheme and (2) to maximize the eventual probability of success in any proposed gasification venture and (3) to optimize the operation and profitability of existing plants and (4) effectively address the environmental aspects.It is the view of the authors that fixed bed gasification technology has a bright future in the areas mentioned above and that Sasol has a unique role in the future application and commercialization of gasification technology globally. The unique skills of Sasol could however be complementary to those of other parties who share our view on the future of gasification and related technologies.

Single-module proteins, such as chymotrypsin inhibitor 2 (CI2), fold as a single cooperative unit. To solve its folding pathway, we must characterize, under conditions that favour folding, its denatured state, its transition state, and its final folded structure. To obtain a ‘denatured state’ that can readily be thus characterized, we have used a trick of cleaving CI2 into two complementary fragments that associate and fold in a similar way to intact protein.Fragment CI2(1–40) – which contains the sequence of the single α-helix, spanning residues 12–24 – and CI2(41–64), and mutants thereof, were analyzed by NMR spectroscopy, the transition state for association/folding was characterized by the protein engineering method, and the structure of the complex was solved by NMR and X-ray crystallography. Both isolated fragments are largely disordered. The transition state for association/folding is structured around a nucleus of a nearly fully formed α-helix, as is the transition state for the folding of intact CI2, from residues Ser12 to Leu21. Ala16, a residue from the helix whose sidechain is buried in the hydrophobic core, makes interactions with Leu49 and Ile57 in the other fragment. Ala16 makes its full interaction energy in the transition state for the association/folding reaction, just as found during the folding of the intact protein.The specific contacts in the transition state form a nucleus that extends from one fragment to the next, but the nucleus is only ‘flickeringly’ present in the denatured state. This is direct evidence for the nucleation-condensation mechanism in which the nucleus is only weakly formed in the ground state and develops in the transition state. The low conformational preferences in the denatured state are not enough to induce significant local secondary structure, but are reinforced by tertiary interactions during the rapid condensation around the nucleus.