Synthetic and X-ray structural and reactivity studies of Cp*RuIV complexes containing bidentate dithiocarbonate, xanthate, carbonate, and phosphinate ligands (Cp* = eta5-C5Me5)

The reaction of [Cp*RuCl2]2 (1; Cp* = eta5-C5Me5) with tetraalkyldithiuram disulfides (R2NC(S)SS(S)CNR2, R = Me, Et), isopropylxanthic disulfide ([iPrOC(S)S]2), and bis(thiophosphoryl) disulfide ([(iPrO)2P(S)S]2) led to the isolation of dark-red crystalline solids of Cp*RuIVCl2(eta2-dithiolate) complexes [dithiolate = S2CNR2, DTCR (2a, R = Me; 2b, R = Et), S2COiPr (3), and S2P(iPrO)2 (4)]. Dichlorido substitution in 2 and 3 with DTCEt and S2COiPr anions yielded RuIV derivatives containing bis(DTC) and mixed DTC-dithiocarbonate ligands. These are the first organoruthenium complexes of such ligands. The reaction of monophosphines with 2a resulted in monochlorido substitution, whereas the analogous reaction with 3 resulted in displacement of both chlorido ligands and reduction of the metal center to RuII. Reduction at Ru was also observed in the reaction of 2a with [CpCr(CO)3]2. Of these complexes, only 2 and 3 are air-stable in the solid state for an extended period. All of the complexes have been spectrally characterized, and selected compounds are also crystallographically characterized.     

The effects of cis–trans configuration of cyclohexane multi-carboxylic acids on colloidal forces in dispersions: steric, hydrophobic and bridging

The effects of cis- and trans-1,2-, trans-1,4-cyclohexanedicarboxylic acid, 95% cis-1,3,5-cyclohexane tricarboxylic acid and cis-1,2,3,4,5,6-cyclohexanehexacarboxylic acid on the yield stress–pH behaviour of concentrated ZrO₂ dispersions are reported. Adsorbed cis-1,2,3,4,5,6-cyclohexanehexacarboxylic acid imparts predominantly steric interactions. It forms a steric barrier keeping the interacting particles apart. Adsorbed cis- and trans-1,2 increase the maximum yield stress and this was attributed to a hydrophobic force resulting from the part of the cyclohexane ring sticking out into the solution which is devoid of charged or hydrophilic group. Adsorbed trans-1,4 increases the maximum yield stress by at least threefold and its configuration favours strong bridging interaction with an adjacent particle. Predominantly, cis-1,3,5 also increases the maximum yield stress but only by 60% at the same additive concentration. This was attributed to a smaller degree of bridging.     

Minimising oil droplet size using ultrasonic emulsification

The efficient production of nanoemulsions, with oil droplet sizes of less than 100 nm would facilitate the inclusion of oil soluble bio-active agents into a range of water based foods. Small droplet sizes lead to transparent emulsions so that product appearance is not altered by the addition of an oil phase. In this paper, we demonstrate that it is possible to create remarkably small transparent O/W nanoemulsions with average diameters as low as 40 nm from sunflower oil. This is achieved using ultrasound or high shear homogenization and a surfactant/co-surfactant/oil system that is well optimised. The minimum droplet size of 40 nm, was only obtained when both droplet deformability (surfactant design) and the applied shear (equipment geometry) were optimal. The time required to achieve the minimum droplet size was also clearly affected by the equipment configuration. Results at atmospheric pressure fitted an expected exponential relationship with the total energy density. However, we found that this relationship changes when an overpressure of up to 400 kPa is applied to the sonication vessel, leading to more efficient emulsion production. Oil stability is unaffected by the sonication process.     

Biodegradable elastomer for soft tissue engineering

In this work we present the synthesis of a biodegradable, elastomeric material with a wide range of mechanical properties. The synthesis of the material was done by condensation polymerization of malic acid and 1,12–dodecandiol. The synthesized materials have low Young’s modulus ranging from about 1 to 4 MPa and a high elongation at break of 25–737% depending on the crosslinking density of the system. The cell growth observed under microscope showed good proliferation at 3 days of culture indicating good biocompatibility and support of L929 cells growth. The fabrication of 3D scaffold from these materials using the super critical CO₂ foaming method was also attempted. This method of scaffold fabrication is appropriate for materials that are easily hydrolysable and it also has the advantage of being a solvent free process. These materials are generally soft, biocompatible and biodegradable making them suitable for tissue engineering of soft tissues that are elastic in nature like muscles and blood vessels.     

Computational aero-acoustic analysis of a passenger car with a rear spoiler

This study proposes an effective numerical model based on the Computational Fluid Dynamics (CFD) approach to obtain the flow structure around a passenger car with wing type rear spoiler. The topology of the test vehicle and grid system is constructed by a commercial package, ICEM/CFD. FLUENT is the CFD solver employed in this study. After numerical iterations are completed, the aerodynamic data and detailed complicated flow structure are visualized using commercial packages, Field View and Tecplot. The wind effect on the aerodynamic behavior of a passenger car with and without a rear spoiler and endplate is numerically investigated in the present study. It is found that the installation of a spoiler with an appropriate angle of attack can reduce the aerodynamic lift coefficient. Furthermore, the installation of an endplate can reduce the noise behind the car. It is clear that the vertical stability of a passenger car and its noise elimination can be improved. Finally, the aerodynamics and aero-acoustics of the most suitable design of spoiler is introduced and analyzed.     

Spatially controlled chemistry using remotely guided nanoliter scale containers

In this communication we describe a new chemical encapsulation and release platform using 3D microfabricated nanoliter scale containers with controlled porosity. The containers can be fabricated of magnetic materials that allow them to be remotely guided using magnetic fields. The favorable attributes of the containers that include a versatile highly parallel fabrication process, precisely engineered porosity, isotropic/anisotropic chemical release profiles, and remote magnetic guiding provide an attractive platform for engineering spatially controlled chemical reactions in microfluidic systems.     

Three‐dimensional visible‐light capsule enclosing perfect supersized darkness via antiresolution

Supersized darkness in three dimensions surrounded by all light in free space is demonstrated theoretically and experimentally in the visible regime. The object staying in the darkness is similar to staying in an empty light capsule because light just bypasses it by resorting to destructive interference. A binary‐optical system is designed and fabricated based on achieving antiresolution (AR), by which electromagnetic energy flux avoids and bends smoothly around a nearly perfect darkness region. AR remains an unexplored topic hitherto, in contrast to the super‐resolution for realizing high spatial resolution. This novel scheme replies on smearing out the point spread function and thus poses less stringent limitations upon the object's size and position since the created dark (zero‐field) area reach 8 orders of magnitude larger than λ² in cross‐sectional size. It functions very well with arbitrarily polarized beams in three dimensions, which is also frequency scalable in the whole electromagnetic spectrum.     

Determination of endocrine-disrupting phenols in water samples by a new manual shaking-enhanced, ultrasound-assisted emulsification microextraction method

Manual shaking-enhanced, ultrasound-assisted emulsification microextraction (MS-USAEME) combined with ultraperformance liquid chromatography (UPLC) with UV detection has been developed for the determination of five endocrine-disrupting phenols (EDPs) in seawater samples and detergent samples: 4-tert-butylphenol (4-t-BP), 4-cumylphenol (4-CP), 4-tert-octylphenol (4-t-OP), 2,4-di-tert-butylphenol (2,4-di-t-BP) and 4-nonylphenol (4-NP). Optimum conditions were found to be: 25 μL 1-bromohexadecane as extraction solvent, 5 mL of aqueous sample and 1 g of NaCl to control the ionic strength; manual shaking for 10 s; ultrasonication for 1 min; centrifugation for 3 min at 5000 rpm (speed). For MS-USAEME, manual shaking for 10 s is essential for effective extraction when the ultrasonic extraction time is as brief as 1 min. The small volume of aqueous sample enhances the effect of manual shaking significantly. For seawater samples, the limit of detection (LOD) was 0.5-2.8 ng mL(-1), the limit of quantification (LOQ) was 1.8-9.3 ng mL(-1) with the relative standard deviation (RSD) in the range 4.2-10.3%. For detergent samples, the LOD was 0.4-2.4 ng mL(-1), LOQ was 1.6-8.2 ng mL(-1) and RSD 4.7-10.0%. The relative recovery was 96-109% for seawater samples and 81-106% for the detergent samples.