Imin-based synthesis of polyfunctionalized dihydro-2-oxypyrroles catalyzed by glycine amino acid via tandem Michael–Mannich cyclocondensation reaction under ambient temperature

Research on Chemical Intermediates - An efficient and mild synthetic route to the convenient one-pot preparation of polyfunctionalized dihydro-2-oxypyrroles has been developed and catalyzed via...     

Ammonia fiber expansion pretreatment and enzymatic hydrolysis on two different growth stages of reed canarygrass

Plant materials from the vegetative growth stage of reed canarygrass and the seed stage of reed canarygrass are pretreated by ammonia fiber expansion (AFEX) and enzymatically hydrolyzed using 15 filter paper units (FPU) cellulase/g glucan to evaluate glucose and xylose yields. Percent conversions of glucose and xylose, effects of temperature and ammonia loading, and hydrolysis profiles are analyzed to determine the most effective AFEX treatment condition for each of the selected materials. The controls used in this study were untreated samples of each biomass material. All pretreatment conditions tested enhanced enzyme digestibility and improved sugar conversions for reed canarygrass compared with their untreated counterparts. Based on 168 h hydrolysis results using 15 FPU Spezyme CP cellulase/g glucan the most effective AFEX treatment conditions were determined as: vegetative growth stage of reed canarygrass--100 degrees C, 60% moisture content, 1.2:1 kg ammonia/kg of dry matter (86% glucose and 78% xylose) and seed stage of reed canarygrass--100 degrees C, 60% moisture content, 0.8:1 kg ammonia/kg of dry matter (89% glucose and 81% xylose). Supplementation by commercial Multifect 720 xylanase along with cellulase further increased both glucose and xylose yields by 10-12% at the most effective AFEX conditions.     

Fabrication of superhydrophobic nanostructured surface on aluminum alloy

A superhydrophobic surface was prepared by consecutive immersion in boiling water and sputtering of polytetrafluoroethylene (PTFE or Teflon®) on the surface of an aluminum alloy substrate. Immersion in boiling water was used to create a micro-nanostructure on the alloy substrate. Then, the rough surface was coated with RF-sputtered Teflon film. The immersion time in boiling water plays an important role in surface morphology and water repellency of the deposited Teflon coating. Scanning electron microscopy images showed a “flower-like” structure in first few minutes of immersion. And as the immersion time lengthened, a “cornflake” structure appeared. FTIR analyses of Teflon-like coating deposited on water treated aluminum alloy surfaces showed fluorinated groups, which effectively reduce surface energy. The Teflon-like coating deposited on a rough surface achieved with five-minute immersion in boiling water provided a high static contact angle (～164°) and low contact angle hysteresis (～4°).     

A flexible microfluidic processor for molecular biology: application to microarray sample preparation

We describe a programmable microfluidic system with onboard pumps and valves that has the ability to process reaction volumes in the sub-microlitre to hundred microlitre range. The flexibility of the architecture is demonstrated with a commercial molecular biology protocol for mRNA amplification, implemented without significant modification. The performance of the microchip system is compared to conventional bench processing at each stage of the multistep protocol, and DNA microarrays are used to assess the quality and performance of bench- and microchip-amplified RNA. The results show that the microchip system reactions are similar to bench control reactions at each step, and that the microchip- and bench-derived amplified RNAs are virtually indistinguishable in differential microarray analyses.     

Nanostructure protein repellant amphiphilic copolymer coatings with optimized surface energy by Inductively Excited Low Pressure Plasma

Statistically designed amphiphilic copolymer coatings were deposited onto Thermanox, Si wafer, and quartz crystal microbalance (QCM) substrates via Plasma Enhanced Chemical Vapor Deposition of 1H,1H,2H,2H-perfluorodecyl acrylate and diethylene glycol vinyl ether in an Inductively Excited Low Pressure Plasma reactor. Plasma deposited amphiphilic coatings were characterized by Field Emission Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, and Water Contact Angle techniques. The surface energy of the coatings can be adjusted between 12 and 70 mJ/m(2). The roughness of the coatings can be tailored depending on the plasma mode used. A very smooth coating was deposited with a CW (continuous wave) power, whereas a rougher surface with R(a) in the range of 2 to 12 nm was deposited with the PW (pulsed wave) mode. The nanometer scale roughness of amphiphilic PFDA-co-DEGVE coatings was found to be in the range of the size of the two proteins namely BSA and lysozyme used to examine for the antifouling properties of the surfaces. The results show that the statistically designed surfaces, presenting a surface energy around 25 mJ/m(2), present no adhesion with respect to both proteins measured by QCM.     

Preconcentration/Separation of Some Metal Ions Using Sodium Dodecyl Sulfate Coated Alumina Modified with Bis(5‐bromo‐2‐hydroxy‐benzaldehyde)‐2‐methyl‐1,5‐pentane Diimine (BBHBPDI) Prior to Their Flame‐AAS Determination

Preconcentration/separation of Co(II), Fe(III), Pb(II), Cr(III), Cu(II) and Cd(II) ions using bis(5‐bromo‐2‐hydroxy‐benzaldehyde)‐2‐methyl‐1,5‐pentane diimine (BBHBPDI) on SDS coated alumina has been reported. The influences of the analytical parameters including pH, ligand and SDS amount, type and concentration of eluent and sample volume on metal ions recoveries were investigated. At optimum values of all variables the relative standard deviation are between 2.5–2.7 and preconcentration factor was 375, while recoveries for all understudy metal ions are higher than 95%, determination limits are between 1.5–2.7. The method has been successfully applied to determination of Co(II), Fe(III), Pb(II), Cr(III), Cu(II) and Cd(II) ions content in some real samples.     

Visual Investigation of Improvement in Extra-Heavy Oil Recovery by Borate-Assisted $$\hbox {CO}_{2}$$-Foam Injection

The significant reduction in heavy oil viscosity when mixed with \(\hbox {CO}_{2}\) is well documented. However, for \(\hbox {CO}_{2}\) injection to be an efficient method for improving heavy oil recovery, other mechanisms are required to improve the mobility ratio between the \(\hbox {CO}_{2}\) front and the resident heavy oil. In situ generation of \(\hbox {CO}_{2}\)-foam can improve \(\hbox {CO}_{2}\) injection performance by (a) increasing the effective viscosity of \(\hbox {CO}_{2}\) in the reservoir and (b) increasing the contact area between the heavy oil and injected \(\hbox {CO}_{2}\) and hence improving \(\hbox {CO}_{2}\) dissolution rate. However, in situ generation of stable \(\hbox {CO}_{2}\)-foam capable of travelling from the injection well to the production well is hard to achieve. We have previously published the results of a series of foam stability experiments using alkali and in the presence of heavy crude oil (Farzaneh and Sohrabi 2015). The results showed that stability of \(\hbox {CO}_{2}\)-foam decreased by addition of NaOH, while it increased by addition of \(\hbox {Na}_{2}\hbox {CO}_{3}\). However, the highest increase in \(\hbox {CO}_{2}\)-foam stability was achieved by adding borate to the surfactant solution. Borate is a mild alkaline with an excellent pH buffering ability. The previous study was performed in a foam column in the absence of a porous medium. In this paper, we present the results of a new series of experiments carried out in a high-pressure glass micromodel to visually investigate the performance of borate–surfactant \(\hbox {CO}_{2}\)-foam injection in an extra-heavy crude oil in a transparent porous medium. In the first part of the paper, the pore-scale interactions of \(\hbox {CO}_{2}\)-foam and extra-heavy oil and the mechanisms of oil displacement and hence oil recovery are presented through image analysis of micromodel images. The results show that very high oil recovery was achieved by co-injection of the borate–surfactant solution with \(\hbox {CO}_{2}\), due to in-situ formation of stable foam. Dissolution of \(\hbox {CO}_{2}\) in heavy oil resulted in significant reduction in its viscosity. \(\hbox {CO}_{2}\)-foam significantly increased the contact area between the oil and \(\hbox {CO}_{2}\) significantly and thus the efficiency of the process. The synergy effect between the borate and surfactant resulted in (1) alteration of the wettability of the porous medium towards water wet and (2) significant reduction of the oil–water IFT. As a result, a bank of oil-in-water (O/W) emulsion was formed in the porous medium and moved ahead of the \(\hbox {CO}_{2}\)-foam front. The in-situ generated O/W emulsion has a much lower viscosity than the original oil and plays a major role in the observed additional oil recovery in the range of performed experiments. Borate also made \(\hbox {CO}_{2}\)-foam more stable by changing the system to non-spreading oil and reducing coalescence of the foam bubbles. The results of these visual experiments suggest that borate can be a useful additive for improving heavy oil recovery in the range of the performed tests, by increasing \(\hbox {CO}_{2}\)-foam stability and producing O/W emulsions.     

Head-to-Tail Dimerization of N-Heterocyclic Diazoolefins

The head-to-tail dimerization of N-heterocyclic diazoolefins is described. The products of these formal (3+3) cycloaddition reactions are strongly reducing quinoidal tetrazines. Oxidation of the tetrazines occurs in a stepwise fashion, and we were able to isolate a stable radical cation and diamagnetic dications. The latter are also accessible by oxidative dimerization of diazoolefins.