Hydrqalumination of Diphenylacetylene

It was found that diphenylacetylene reacts at 55[ddot]C with i-Bu₂AlH to form cis-vinylalane. On the other hand, i-Bu₂AlH adds mostly in anti-manner to diphenylacetylene at 110[ddot] C.     

Effect of fluid properties on ultrasound assisted liquid-liquid extraction in a microchannel

When immiscible liquids are subjected to an ultrasonic field, they form emulsions. This principle has been used to improve the mass transfer characteristics of a liquid-liquid extraction process in microreactor systems. The formation of emulsion and its characteristics are prominently dependent on the properties of the liquids used and this also holds true for emulsion brought about by ultrasound. This paper focuses on the properties of fluids that are reported to have an influence on the cavitation behaviour, namely viscosity, interfacial tension and vapour pressure. These properties were examined by changing the solvent of the organic phase in the hydrolysis of p-nitrophenyl acetate. The study is performed by comparing pairs of solvents that are different in one property but similar in the other two. The pairs selected are toluene – chlorobenzene for viscosity, toluene – methyl Isobutyl ketone for interfacial tension and methyl isobutyl ketone – 2-Methyl tetrahydrofuran for vapour pressure effects. A qualitative study was performed with a high-speed camera in flow to understand the emulsification initiation mechanisms and behaviours. These findings were further explored by performing the sonicated emulsion in a batch-sonicated reactor. The quantitative analysis of the fluid properties was evaluated and compared based on the relative percentage increase in yield upon sonication with respect to their individual silent conditions. The quantitative results were further supported by the quantification of the emulsion performed with an FBRM probe. The results indicate a two times improvement in yield with solvent of lower viscosity as 2 times more droplets were formed in the emulsion. Both the solvent systems with higher interfacial tension and vapour pressure had an improved yield of 1.4 times owing to larger number of droplets formed.     

Ultrasound assisted synthesis of amide functionalized metal-organic framework for nitroaromatic sensing

Nano plates of zinc(II) based metal-organic framework (MOF) were prepared via ultrasonic method without any surfactants at room temperature and atmospheric pressure. Control of particle size and morphology was enhanced in this synthesis method. Nano plates of an interpenetrated amide-functionalized metal-organic framework, [Zn₂(oba)₂(bpfb)]·(DMF)₅, TMU-23, (H₂oba = 4,4′-oxybis(benzoic acid); bpfb = N,N′-bis-(4-pyridylformamide)-1,4-benzenediamine, DMF = N,N-dimethyl formamide), was synthesized under ultrasound irradiation in different concentrations of initial precursor. The nano structure and morphology of the synthesized MOF were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder X-ray diffraction, thermo gravimetric analysis (TGA), elemental analysis and FTIR spectroscopy. Moreover, Fluorescence emissions of nanoplates have been studied. Amide-functionalized MOF shows high selectivity for sensing of nitroaromatic compounds such as nitrophenol, nitroaniline, and nitrobenzene in acetonitrile solution. Fluorescence intensity decreased with increasing contents of nitroaromatics in acetonitrile solution due to fluorescence quenching effect.     

Investigation of stability,consistency, and oil oxidation of emulsion filled gel prepared by inulin and rice bran oil using ultrasonic radiation

Inulin, rice bran oil and rosemary essential oil were used to produce high quality emulsion filled gel (EFG) using ultrasonic radiation. Response surface methodology was used to investigate the effects of oil content, inulin content and power of ultrasound on the stability and consistency of prepared EFG. The process conditions were optimized by conducting experiments at five different levels. Second order polynomial response surface equations were developed indicating the effect of variables on EFG stability and consistency. The oil content of 18%; inulin content of 44.6%; and power of ultrasound of 256 W were found to be the optimum conditions to achieve the best EFG stability and consistency. Microstructure and rheological properties of prepared EFG were investigated. Oil oxidation as a result of using ultrasonic radiation was also investigated. The increase of oxidation products and the decrease of total phenolic compounds as well as radical scavenging activity of antioxidant compounds showed the damaging effect of ultrasound on the oil quality of EFG.     

Ultrasound irradiation effect on morphology and size of two new potassium coordination supramolecule compounds

Two new potassium coordination supramolecular compounds (2D and 1D), [K(H₃L)(H₂L)(H₂O)]_n·H₂O (1) and [K(H₂L′)(HL′)(H₂O)₂]·H₂O (2), (L = 1,3,5-tricarboxylic acid, L′ = 2,6-pyridinedicarboxylic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), FT-IR spectroscopy and elemental analyses. Single crystal X-ray analyses on compounds 1 and 2 show that K⁺ ions are 3- and 7-coordinated, respectively. Additionally, H-bonds incorporate the layers and chains in 1 and 2 into 3D and 2D (along (0,0,1) direction) frameworks. Topological analysis shows that the compound 1 and 2 are 3,6-coordinated kgd and 2,4-coordinated 2,4C4 net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG) and differential thermal analyses (DTA) and compared each other. The role of different parameters like temperature, reaction time and ultrasound irradiation power on the growth and morphology of the nano-structures are studied. Results suggest that an increase of temperature, sonication power and reduction of reaction time led to a particle size decrease.     

Study and optimization of the ultrasound-enhanced cleaning of an ultrafiltration ceramic membrane through a combined experimental–statistical approach

Membrane fouling is one of the main drawbacks of ultrafiltration technology during the treatment of dye-containing effluents. Therefore, the optimization of the membrane cleaning procedure is essential to improve the overall efficiency. In this work, a study of the factors affecting the ultrasound-assisted cleaning of an ultrafiltration ceramic membrane fouled by dye particles was carried out. The effect of transmembrane pressure (0.5, 1.5, 2.5 bar), cross-flow velocity (1, 2, 3 m s⁻¹), ultrasound power level (40%, 70%, 100%) and ultrasound frequency mode (37, 80 kHz and mixed wave) on the cleaning efficiency was evaluated. The lowest frequency showed better results, although the best cleaning performance was obtained using the mixed wave mode.A Box–Behnken Design was used to find the optimal conditions for the cleaning procedure through a response surface study. The optimal operating conditions leading to the maximum cleaning efficiency predicted (32.19%) were found to be 1.1 bar, 3 m s⁻¹ and 100% of power level.Finally, the optimized response was compared to the efficiency of a chemical cleaning with NaOH solution, with and without the use of ultrasound. By using NaOH, cleaning efficiency nearly triples, and it improves up to 25% by adding ultrasound.     

Probabilistic approaches to compute uncertainty intervals and sensitivity factors of ultrasonic simulations of a weld inspection

For comprehension purpose, numerical computations are more and more used to simulate the propagation phenomena observed during experimental inspections. However, the good agreement between experimental and simulated data necessitates the use of accurate input data and thus a good characterization of the inspected material. Generally the input data are provided by experimental measurements and are consequently tainted with uncertainties. Thus, it becomes necessary to evaluate the impact of these uncertainties on the outputs of the numerical model. The aim of this study is to perform a probabilistic analysis of an ultrasonic inspection of an austenitic weld containing a manufactured defect based on advanced techniques such as polynomial chaos expansions and computation of sensitivity factors (Sobol, DGSM). The simulation of this configuration with the finite element code ATHENA2D was performed 6000 times with variations of the input parameters (the columnar grain orientation and the elastic constants of the material). The 6000 sets of input parameters were obtained from adapted statistical laws. The output parameters (the amplitude and the position of the defect echo) distributions were then analyzed and the 95% confidence intervals were determined.     

Flame retardant high density polyethylene optimized by on-line ultrasound extrusion

The effect of on-line ultrasound application by a special static mixer die which promotes extensional flow simultaneously during the single screw extrusion process was thoroughly studied. The proportion of aluminum trihydroxide (ATH) used as flame retardant on high density polyethylene (HDPE) was optimized. The morphological, thermal, flammability, combustion, mechanical and rheological properties of the materials were investigated. The morphological study pointed out that this process is able to strongly reduce the size of ATH particles and improve their dispersion and distribution within the polymer matrix. The addition of zinc borate (ZB) at low concentration (namely 3 phr) showed its well-known synergistic effect in the thermal, oxygen index and fire combustion behavior. According to the UL94 standard, the rating for all materials tested changed from HB to V2, with respect to materials prepared without ultrasound; furthermore a rating V0 was achieved only with the addition of 2 phr organo-clay. Rheological results under simple and small amplitude oscillatory shear flow confirmed the enhanced particle dispersion and finer particle morphology evidenced by larger values of the moduli and by deviations from the semicircular shape observed in the Cole–Cole diagram. Mechanical properties such as Izod impact resistance, tensile strength, strain at break and tenacity were also improved by the on-line ultrasound process. In this work, the appropriate on-line ultrasound extrusion conditions to use the lowest ATH content (30 phr or 21.5 in wt%) were found, rendering HDPE optimized flame retardant materials with improved processability and mechanical properties.     

Diphenyl cyclopropenone-centered polymers for site-specific CO-releasing and chain dissociation

The synthesis and stimuli-responsiveness of a diphenyl cyclopropenone(DPCP)-centered poly(methyl acrylate)(PMA)are presented.DPCP-centered PMA could release carbon monoxide(CO)upon UV light in a switched on-and-off manner.The CO-releasing process can be reported by the variations in photoluminescence spectra.In addition,DPCP moiety covalently embedded in the crosslinked polyurethane could also release CO under UV light.Of special,DPCP-centered PMA in solution was selectively dissociated at the phenol ester bond under the ultrasound,and a force-induced hydrolyzation reaction was revealed by D20 exchanging^1 H NMR spectra.The kinetic study reveals that small quantity of water could enhance the chain scission rate.This work provides a DPCP-centered polymer for sitespecific CO-releasing and chain dissociation.     

反射式Sagnac干涉光纤电流互感器的传感头误差研究

阐述了反射式Sagnac干涉型电流传感器的原理,对Sagnac型光纤电流传感器进行了深入的理论研究,建立了完整的系统理论模型。采用偏振系统的Jones矩阵对反射式Sagnac干涉型电流传感器的偏振误差进行了研究,并对光纤传感头中的线性双折射、圆双折射对测量准确度的影响进行了模拟分析,从理论上得到了反映影响规律的曲线。仿...