A three-component cyclocondensation reaction for the synthesis of new triazolo[1,5-a]pyrimidine scaffolds using 3-aminotriazole,aldehydes and ketene N,S-acetal

Molecular Diversity - This study describes the use of 3-aminotriazole, different aldehydes and N-methyl-1-(methylthio)-2-nitroethenamine as a ketene N,S-acetal in a three-component condensation for...     

Coupling of CFD Simulations and Population Balance Modeling to Predict Brownian Coagulation in an Emulsion Polymerization Reactor

In this study a framework consisting of a computational fluid dynamics simulation coupled to a population balance model for the modeling of emulsion polymerizations is proposed. The combined approach is used to understand the impact of changing length and time scales, as well as mixing conditions on the particle size distribution (PSD) of a polymer latex under different conditions. It is shown that the effect of agitation rate can have a profound impact on the distribution of ionic species in the reactor, and thus on the evolution of the PSD.

     

Synthesis and application of cinnamate-functionalized rubber for the preparation of UV-curable films

A butyl rubber derivative that can be cured upon exposure to UV light in the absence of additional chemical additives was developed. This polymer was prepared by the reaction of hydroxyl-functionalized butyl rubber with cinnamoyl chloride to provide a cinnamate functionalized rubber. The cinnamate content was varied by starting with derivatives prepared from butyl rubber containing either 2 or 7 mol% isoprene. The kinetics of the cross-linking was studied by UV–visible spectroscopy and it was found to vary according to the film thickness. The changes in gel content and volume swelling ratio with irradiation time were dependent on the cinnamate content. Toxicity studies suggested that the cross-linked materials do not leach toxic molecules. The approach was also applied to obtain cross-linked films of butyl rubber-poly(ethylene oxide) graft copolymers, leading to surfaces that resisted the adhesion and growth of cells. Thus the approach is versatile and is of particular interest when non-leaching coatings of cross-linked butyl rubber are desired for biomedical or other applications.     

Characterization,slab-pair modeling and phase analysis of circular fishnet metamaterials

Planar metamaterials, which have incident to normal plane excitation unlike SRR-type structures and that are easily fabricated in multilayer form, have received great interest in recent years. In this paper, one-dimensional and polarization independent circular fishnet metamaterials and their equivalent discontinuous slab-pair modeling for tuning resonance frequencies are introduced. After the numerical and experimental demonstration of the inclusions, the standard retrieval characterization methods and the correspondent/related backward-wave propagation observation are realized in order to check the physical explanation mentioned in the paper. In addition, a detailed phase analysis is performed in order to demonstrate the application of the suggested structure as a phase compensator.     

Synthesis,characterization, and design of a photocatalyst based on BiOBr nanoplates and tin porphyrin with enhanced visible light photocatalytic activity

Research on Chemical Intermediates - The bismuth oxybromide (BiOBr) photocatalyst was first synthesized via a simple co-precipitation method. To improve the visible light photocatalytic activity of...     

Biogas Production from N-Methylmorpholine-N-oxide (NMMO) Pretreated Forest Residues

Lignocellulosic biomass represents a great potential for biogas production. However, a suitable pretreatment is needed to improve their digestibility. This study investigates the effects of an organic solvent, N-Methylmorpholine-N-oxide (NMMO) at temperatures of 120 and 90 °C, NMMO concentrations of 75 and 85 % and treatment times of 3 and 15 h on the methane yield. The long-term effects of the treatment were determined by a semicontinuous experiment. The best results were obtained using 75 % NMMO at 120 °C for 15 h, resulting in 141 % increase in the methane production. These conditions led to a decrease by 9 % and an increase by 8 % in the lignin and in the carbohydrate content, respectively. During the continuous digestion experiments, a specific biogas production rate of 92 NmL/gVS/day was achieved while the corresponding rate from the untreated sample was 53 NmL/gVS/day. The operation conditions were set at 4.4 gVS/L/day organic loading rate (OLR) and hydraulic retention time (HRT) of 20 days in both cases. NMMO pretreatment has substantially improved the digestibility of forest residues. The present study shows the possibilities of this pretreatment method; however, an economic and technical assessment of its industrial use needs to be performed in the future.     

Synthesis of Poly (methyl methacrylate)/Zinc Oxide Nanocomposite with Core-Shell Morphology by Atom Transfer Radical Polymerization

A method to prepare zinc oxide (ZnO) nanoparticles with a covalently bonded poly(methyl methacrylate) (PMMA) shell by surface initiated atom transfer radical polymerization (ATRP) was reported. First, the initiator for ATRP was covalently bonded onto the surface of zinc oxide nanoparticles through our novel method. Firstly, the surface of ZnO nanoparticle was treated with 3-aminopropyl triethoxysilane, a silane coupling agent, and then this functionalization nanoparticle was reacted with α-chloro phenyl acetyl chloride to prepare atom transfer radical polymerization macroinitiator. The metal-catalyzed radical polymerization of MMA with ZnOmacroinitiator was performed using a copper catalyst system to give the ZnO-based nanoparticles hybrids linking PMMA segments (poly (methyl methacrylate)/zinc oxide nanocomposite). These hybrid nanoparticles had an exceptionally good dispersability in organic solvents and were subjected to detailed characterization using FTIR, TEM and TGA and DSC analyzed.     

Reverse phase HPLC determination of sunitinib malate using UV detector,its isomerisation study,method development and validation

Sunitinib malate, as an anticancer compound and a multi-targeted tyrosine-kinase inhibitor for treatment of glioma, was comprehensively studied by using different liquid chromatography methods. Since sunitinib malate shows Z-E isomerism, various reverse phase high performance liquid chromatography (RP-HPLC) programs were designed to access quantitative determination and good separation of Z-E stereoisomers. Moreover, some impurities including N-oxide and impurity B were to be separated from the main isomer with acceptable resolution. In the present work, different RP-HPLC programs were developed in which the type of mobile phase, flow rate, pH, and temperature were optimized to reach the best analysis conditions and control the rate of Z to E conversion. In addition, the effect of some operational parameters during the solution preparation including initial concentration of the analyte, temperature, pH, and type of solvent on the stability of Z isomer were investigated. The opted conditions for quantitative analysis were C8-Hector column as stationary phase, methanol as solvent, ammonium acetate buffer containing triethylamine as mobile phase, the pH of mobile phase of 8.5, the flow rate of 1.0 mL/min, and detection at 425 nm. In this situation the peaks of E and Z isomers were at 16.3 and 19.7 min. Full validation of the designed method was done based on ICH guidelines.     

Vacuum solution of a linear red-shift based correction in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>) gravity

In this paper we have considered a red-shift based linear correction in derivative of action in the context of vacuum f (R) gravity. Here we have found out that the linear correction may describe the late time acceleration which is appeared by SuperNovae Ia with no need of dark energy. Also we have calculated the asymptotic action for the desired correction. The value of all solutions may reduce to de’ Sitter universe in the absence of correction term.     

Low-cost low-threshold diode end-pumped Tm:YAG laser at 2.016?μm

We report a low-threshold continuous-wave Tm:YAG laser that can be excited near 785?nm with low-cost, single-mode AlGaAs laser diodes. Low-threshold operation was achieved using a tightly focused, astigmatically compensated x-cavity containing a 2-mm-thick Tm:YAG crystal with 5?% Tm³⁺ concentration. Two linearly polarized single-mode diodes operating at 785.8?nm were polarization coupled to end pump the resonator. With a 6?% output coupler, as high as 32?mW of output power could be obtained at 2016?nm with 184?mW of incident pump power. The output could be further tuned in the 1935?C2035?nm range. Slope efficiency measurements indicated that cross-relaxation was very effective at this doping level. With a 2?% output coupler, lasing could be obtained with as low as 32.3?mW of pump power. In the limit of vanishing output coupling, the incident threshold pump power could be reduced to as low as 25?mW. To our knowledge, this is among the lowest lasing thresholds reported to date for continuous-wave, room-temperature thulium lasers.