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The tetraruthenium tetrahydrido carbonyl cluster Ru4(µ-H)4(CO)12 (1) reacts with diphenylvinylphosphine under thermal activation to give the substitution products Ru4(µ-H)4(CO)12−n(κ1-Ph2PCH=CH2)n, (2) (n = 3 (a); 4 (b)). Both 2a and 2b have been completely characterized, including by single-crystal X-ray diffraction analysis. Each of the diphenylvinylphosphine ligands in 2a and 2b is terminally bound, via the phosphorus atom, to a different ruthenium metal center, while the hydride positions in the Ru4(µ-H)4 cores retain the D2d symmetry of the parent cluster 1. Clusters 2a and 2b were able to retain their structural integrity at elevated temperatures. Graphic Abstract: Thermolysis of Ru4(μ-H)4(CO)12 (1) in cyclohexane with diphenylvinylphosphine afforded the tri- and tetra-substituted derivatives Ru4(μ-H)4(CO)9(κ1-Ph2PCH=CH2)3 (2a) and Ru4(μ-H)4(CO)8(κ1-Ph2PCH=CH2)4 (2b). For both substituted clusters, the diphenylvinylphosphine ligands are bound terminally to the tetraruthenium core via the phosphorus atoms while the hydride positions retain the D2d symmetry of the parent cluster 1.[Figure not available: see fulltext.] Ministry of Education (MOE) Nanyang Technological University This work was supported by Hwa Chong Institution as well as Nanyang Technological University and the Ministry of Education with a research Grant (No. M4011158).

This study reports that the C2–C2 aldolization in ethanol conversion to C4 products, particularly butadiene, can be catalyzed by silica-supported LaMnO3 catalysts. The concentration and strength of Mn4+ was discovered to be related to the particle size of supported LaMnO3: the smaller the particle size is, the higher the concentration and acidity of Mn4+ are. The presence of high concentration and acidity of Mn4+ of small LaMnO3 particles concurrently increases the amount of weak basic nonstoichiometric oxygen, with which the surface concentration of Lewis acid–base adducts can be elevated. The Mn4+/nonstoichiometric oxygen pair is intrinsically active in C2–C2 aldolization, and the concentration of the paired site is positively correlated to the selectivity of C4 products. By coreacting ethanol with its evolved intermediates, that is, acetaldehyde and crotonaldehyde, we discovered the aldol condensation of acetaldehyde molecules to be rate-limiting. Accordingly, a plausible mechanism of aldolization of a...

Urease were known to catalyze the conversion of urea to ammonia and carbon dioxide. Microbial urease has demonstrated its benefits in wide biotechnological, agricultural, medicinal and engineering application. There are number of diverse microbial species contribute to urease activity in different natural habitats like soil, ocean and in various geological formation. For this study, urease bacteria were screened and isolate from acidic peat in Sarawak, Malaysia. Five distinct and diverse bacterial strains that were able to produce urease constitutively were selected to be characterized with respect to morphology, biochemical test, growth conditions and urease activity. The selected strain showed their capability to precipitate calcium carbonate (CaCO3). Hence, the isolates could be potential source of acid ureases that can be use in various industrial utilizations. 16S rRNA sequencing and phylogenetic analysis found that the selected isolates belong to the genus of Bacillus.

This work was devoted to three Ir(III) complexes having large conjugation planes and various numbers of fluorine substituents for optical oxygen sensing purpose. These F atoms might broaden electronic distribution of excited electrons and increase their decay lifetime, hoping to increase sensing collision probability of excited electrons with O 2 molecules. These Ir(III) complexes were analyzed by single crystal analysis and density functional theory calculation. Photophysical measurement suggested that their phosphorescent emission was quenchable by O 2 gas. By doping these Ir(III) complexes into fibrous films through electrospinning method, their oxygen sensing performance was explored. The presence of F atoms improved oxygen sensing performance. High sensitivity (12.89), short response (8 s), good stability and, more importantly, linear response were observed.

Tubes with various cross-sectional shapes are widely used in automotive and bicycle manufacture for lightweight considerations. This study proposes a compound forming process for hydroforming a rectangular cross-sectional tube of aluminum alloys AA6061-O. The compound forming process is divided into crushing, hydroforming, and calibration. The finite element simulation software DEFORM was used to analyze the plastic deformation pattern of the tube during the compound forming processes and determine feasible loading paths that can generate a uniform thickness distribution, a lower internal pressure, and a smaller clamping force. The effects of varied internal pressures on the product shapes, thickness distributions, and forming loads are discussed. A self-designed hydroforming test machine with an internal pressure capacity of 30 MPa and axial feeding force of 40 tons was used to conduct hydroforming experiments. The experimental results of the product thickness distributions and dimensions were compared with simulation results, and the validity of the FE modeling is confirmed. Sound products with the required shape and dimensions can be obtained using the proposed hydraulic compound forming process with a low internal pressure of 8 MPa.

In this paper, two up-conversion optical sensing systems for cysteine detection were constructed, using two rhodamine derivatives as chemosensors. To improve chemosensor photostability, up-conversion NaYF 4 :Yb 3+ /Er 3+ nanocrystals were used as excitation host. This host was then modified with α-cyclodextrin to improve its water-dispersibility. The energy transfer between this excitation host and chemosensors was confirmed through spectral analysis and emission decay lifetime comparison. Job's plot experiment suggested that these chemosensors followed a simple recognition mechanism towards Cys with binding stoichiometry of 1:1. These chemosensors showed emission “turn-on” effect towards Cys with good selectivity and linear response. Sulfur substituent effect was found positive to improve chemosensor selectivity and linearity.

The solubility of d -phenylglycine methyl ester hydrochloride in water, methanol, ethanol, acetone, ethyl acetate, and toluene as well as in methanol-ethyl acetate and methanol-toluene binary mixtures with different compositions was measured under atmospheric pressure and from 283.15 K to 333.15 K using a dynamic laser method. Experimental data were correlated with the modified Apelblat, combined nearly ideal binary solvent/Redlich-Kister, and nonrandom two-liquid models. Computational results showed that the solubility of d -phenylglycine methyl ester hydrochloride increased monotonically with increasing temperature in individual and mixed solvents. It also increased monotonically with increasing methanol concentration in binary mixtures. The evaluation of model accuracy and applicability demonstrated that all models provided good fits. Changes in the standard enthalpy, entropy, and Gibbs free energy of d -phenylglycine methyl ester hydrochloride upon dissolution were calculated to obtain thermodynamics data. The results showed that the dissolution followed a non-spontaneous and endothermic process, and in most cases enthalpy was the main contributing parameter.

In this paper, eight chemosensors derived from rhodamine 6G were synthesized for Hg(II) detection. To minimize their photobleaching, we used an up-conversion material β-NaYF 4 :Yb 3+ /Er 3+ as excitation host. Under near-IR laser of 980 nm, up-conversion emission of this excitation host overlapped well with absorption of our chemosensors. Efficient energy transfer from this excitation host to our chemosensors was confirmed by emission decay lifetime analysis. Job's plot measurement suggested that the complexation equilibrium between our chemosensors and Hg(II) was a simple one with binding stoichiometry of 1:1. Host:chemosensor systems exhibited fluorescence “turn-on” effect toward Hg(II) with good selectivity and linear response. We tentatively discussed the correlation between sensing characteristics and chemosensor structure. It was concluded that S substituent increased association constant and selectivity, but decreased photostability of our chemosensors.

Peat is known as problematic ground with low bearing capacity and extensively high compressibility. Ordinary Portland cement (OPC) and lime were usually used to tackle unfavourable characteristics of peat by improving it with its cementation effect. However, little was known of the effect of bio-cementation towards peat improvement. Bio-cementation or commonly known as Microbial-induced calcite precipitation (MICP) has been recently introduced as a ground improvement alternative for geotechnical engineering application. MICP performed by utilising metabolic pathways of non-pathogenic urealytic bacteria that precipitates calcium carbonate (CaCO3) crystal as cementation binder that seal soil particles together increasing soil strength. MICP of inorganic soil was extensively explored, and only limited was done for organic soil. This study explores on the effect of different surcharge preloading of 18kPa, 36kPa and 48kPa towards Microbial-Induced Calcite Precipitation (MICP) treatment of tropical peat. Fibrous peat studied were obtained from Miri, Sarawak and cured under a submerged condition with different vertical preload for seven days. Laboratory study including unconfined compression test, quantification of carbonates precipitated, and moisture content of stabilised specimens was observed to evaluate the performance of stabilisation effort. Unconfined compressive strength (UCS) of treated specimens was observed to be higher than untreated specimens with the highest increase of UCS up to 469%. However, CaCO3 precipitation amount for this study was observed to decrease with increasing surcharge preload.

Three adsorbents, that is, 4-N,N-dimethylaminopyridine (DMAP), tetrabutylammonium isonicotinate (TBAIN), and methyl isonicotinate (MIN), were employed for blocking charge recombination in the dye-sensitized solar cells (DSCs) with poly(ethylene oxide)/poly(ethylene glycol) blend electrolyte. Photovoltage–light intensity measurements showed the adsorbents not only decrease the recombination rate but also prompt the nonideality of recombination. The energy level of the TiO2 band edge (Ec) is elevated by the adsorbents, which also result in the increase in the characteristic temperature (T0), reflecting a deeper distribution of the electrons at the surface states. An electron transfer model on the basis of the Marcus theory was applied to calculate the rate of nonideal recombination as well as the ideality factor. The results indicate that the increases in Ec and T0 both foster the nonideal recombination. The decreased recombination is further attributed to the upward shift of the TiO2 band edge, which reduc...

The heat feedback of flame plumes is a main form of energy transfer and a significant contributor to fire growth and spread. The paper introduces the case of heptane pool fires in open spaces. A corresponding formula is proposed along with the simplified model of plume heat feedback based on the analysis of heat balance equations of pool fires. A hybrid CFD model of heptane pool fire simulation methodology is used to study the fire characteristic parameters and plume heat feedback effects in the combustion process of pool fires. The results suggest that plume heat radiation and convection effects cause about 53% and 37% of the total mass loss rate in the combustion process of 1m 2 heptane pool fire and thus that they play an important role on the occurrence and development of liquid fires.

Poly(N-propyl-vinylimidazolium iodide-co-poly(ethylene glycol) methyl ether methacrylate) with a comb-like configuration was synthesized. The copolymer and its blend with poly(ethylene oxide) (PEO) were used to prepare the polymer electrolytes for solid dye-sensitized solar cells. The amorphous characteristics and the ion-crosslinking effects of the copolymer and its blend electrolyte were analyzed by WAXS, DSC and FT-IR. The copolymer and PEO in the blend electrolyte were shown to play the roles of decreasing the crystallinity and breaking the ion-crosslinking, respectively. The blend electrolytes thus presented the highest ionic conductivity among the prepared electrolytes. The as-prepared DSSCs yielded the energy conversion efficiency of 3.46% at 100 mW cm−2. The impedance results indicated the improved photovoltaic performance of the blend electrolyte was originated from the increased ionic diffusion coefficient and the prevented downward movement of the conduction band edge of TiO2.

4-N,N-Dimethylaminopyridine (DMAP) was introduced into poly(ethyleneoxide)/oligo(ethylene glycol) (PEO/PEG) electrolytes for dye-sensitized solar cells (DSCs). The improved photovoltaic performance of DMAP-doped DSCs was attributed to the integrated effects of the upward displacement of the TiO2 band edge and the decrease in the electron recombination rate. Remarkably, the presence of DMAP suppresses electron recombination via two combined pathways involving the dissociation of triiodide to iodide by a complexation reaction and a modification of the surface state distribution in the band gap of TiO2. With the addition of DMAP, the open-circuit voltage enhances dramatically. The short-circuit photocurrent density has a small increase at low DMAP concentration and drops afterwards. The power conversion efficiency is 4.07%, which corresponds to a 63% increase over that of the DSC without DMAP.

The ability of Candida albicans to adhere to host tissue may well represent an important virulence trait of this opportunistic fungal pathogen. The initiation of lesions at specific tissue locations in the host appears due to specific adherence interactions between adhesins of C. albicans and host cell surface ligands. We and others have found that adhesins appear associated with the phosphomannoprotein of the candidal cell surface. Hydrophilic yeast cells specifically attach to mouse splenic marginal zone macrophages via adhesins that are associated with the glycan portion of the phosphomannoprotein complex. Treatment of yeast cells with β-mercaptoethanol causes release of the fungal adhesin. The adhesin activity is preserved following boiling or digestion with proteolytic enzymes, but is lost following α-mannosidase digestion or periodate oxidation, thus giving support to the mannan nature of the adhesin (s). Hydrolysis of the mannan adhesins by 10mM HCl yields acid-stable and acidlabile moieties, and adhesin sites are associated with both moieties. Adhesin activity in the acid-stable part appears to involve the α-1, 6-linked mannose backbone and the α-1, 2-linked mannosyl side chains. In the acid-labile portion, a β-1, 2-linked tetramannose side-chain shows strong adhesin activity. In related work, we found that specific elimination of macrophages results in increased susceptibility of mice to disseminated candidiasis. In addition, mice induced to make an antibody response against the adhesin preparation are more resistant to disease. Our results indicate that macrophages are important in host resistance against disseminated candidiasis, and we speculate that antibodies specific for mannan adhesins aid in host resistance.

With high-determinacy and no subsurface damage, Magnetorheological Finishing (MRF) has become an important tool in fabricating high-precision optics. But for large mirrors, the application of MRF is restricted by its small removal function and low material removal rate. In order to improve the material removal rate, shorten the processing cycle, we proposed a new MRF concept, named Belt-MRF to expand the application of MRF to large mirrors and made a prototype with a large remove function, using a belt instead of a very large polishing wheel to expand the polishing length. A series of experimental results on Silicon carbide (SiC) and BK 7 specimens and fabrication simulation verified that the Belt-MRF has high material removal rates, stable removal function and high convergence efficiency which makes it a promising technology for processing large aperture optical elements.