Effective preparation and characterization of montmorillonite/poly(ε‐caprolactone)‐based polyurethane nanocomposites

In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Enhanced biodegradation of carbamazepine after UV/H2O2 advanced oxidation

Carbamazepine is one of the most persistent pharmaceutical compounds in wastewater effluents due to its resistance to biodegradation-based conventional treatment. Advanced oxidation can efficiently degrade carbamazepine, but the toxicity and persistence of the oxidation products may be more relevant than the parent. This study sets out to determine whether the products of advanced oxidation of carbamazepine can be biotransformed and ultimately mineralized by developing a novel methodology to assess these sequential treatment processes. The methodology traces the transformation products of the (14)C-labeled carbamazepine during UV/hydrogen peroxide advanced oxidation and subsequent biotransformation by mixed, undefined cultures using liquid scintillation counting and liquid chromatography with radioactivity, mass spectrometry, and UV detectors. The results show that the oxidation byproducts of carbamazepine containing a hydroxyl or carbonyl group can be fully mineralized by a mixed bacterial inoculum. A tertiary treatment approach that includes oxidation and biotransformation has the potential to synergistically mineralize persistent pharmaceutical compounds in wastewater treatment plant effluents. The methodology developed for this study can be applied to assess the mineralization potential of other persistent organic contaminants.     

Improved electrical conductivity of a non-covalently dispersed graphene–carbon nanotube film by chemical p-type doping

Using a high-pressure air spray we developed a method to deposit electrically-conducting thin films consisting of non-covalently dispersed graphene and carbon nanotubes. The graphene–carbon nanotube film was immersed in a nitric acid and followed by exposure to fuming nitric acid. The acid treatment induced an increased concentration of atomic nitrogen on the graphene basal plane and carbon nanotube sidewall. This result indicates chemical p-type doping of the graphene oxide–carbon nanotube film. After the two acid treatments, the spray coated graphene oxide–carbon nanotube films on a glass substrate exhibit a low sheet resistance of 171 Ω/sq, and a high transmittance of 84% at a wavelength of 550 nm.     

Manufacture and quality evaluation of purple sweet potato Makgeolli vinegar using a 2-stage fermentation

Purple sweet potato makgeolli vinegar made using a 2-stage fermentation method was evaluated. The highest alcohol concentration was 4% in a growth medium containing Acetobacter aceti ATCC 15973. Purple sweet potato makgeolli vinegar (PMV) had higher pH and lower acidity values than rice makgeolli vinegar (RMV). The total polyphenol content was 327.14 mg of GAE/L and the DPPH radical scavenging activity was 67.63% for PMV. Both values were much higher than for RMV. The total polyphenol and the DPPH radical scavenging activities of PMV decreased slowly during storage for 20 days, showing that stability of the antioxidant effect during storage was maintained.     

Artificial intelligence in predicting extraction of anti-cancer compounds

Saponins from the particulate Saponaria vaccaria L. seeds (0.29–0.84 mm, 15.35–61.40 g H₂O/100 g dry mass) were extracted for methanol concentrations (MeOH) of 30, 50, 70, and 90 mL/100 mL H₂O and temperatures (T) of, 30, 45, and 60 °C at ten extraction intervals (t) between 1 and 180 min. A calibration equation was developed from the liquid-chromatogram–mass spectroscopy peaks to quantify the extract yields (mg mL⁻¹) for various types of saponins. An artificial neural network (ANN) with three inputs, MeOH, T, and t predicted the extraction kinetics and the yields with less than ca. 12% error. The ANN model not only slightly outperformed the numerical diffusional model, but it also made the prediction simple and faster eliminating the use of the partition coefficient and the effective diffusivity. Therefore an ANN model can be a right approach to predict the yields of saponins and similar products.     

Sub-30 nm gate template fabrication for nanoimprint lithography using spacer patterning technology

In this study, we present a spacer patterning technology for sub-30 nm gate template which is used for nano-scale MOSFETs fabrication. A spacer patterning technology using a poly-silicon micro-feature and a chemical vapor deposition (CVD) SiO2 spacer has been developed, and the sub-30 nm structures by conventional dry etching and chemical mechanical polishing are demonstrated. The minimum-sized features are defined not by the photolithography but by the CVD film thickness. Therefore, this technology yields a large-area template with critical dimension of minimum-sized features much smaller than that achieved by optical lithography.     

Transparent conductive film fabrication using intercalating silver nanoparticles within carbon nanotube layers

Carbon nanotubes have received attention as alternative materials to indium tin oxide for application in transparent conductive films. Their electrical conductivity, however, still has to be improved. In this study, a layer-by-layer self-assembly process was demonstrated using nano-silver-coated carbon nanotubes, which help improve electrical conductivity. The method was based on the pi-pi interaction between the side walls of the carbon nanotubes and nano-silver clusters that were functionalized with benzyl mercaptan. The self-assembled nano-silver cluster monolayer on the surface of the nanotubes can reduce the interfacial contact resistance, thereby leading to high conductivity at a high transparency. The compound was characterized via scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and the four-point probe method.     

Optimization of pea protein and citrus fiber contents for plant based stirred soymilk yogurt using response surface methodology

Food Science and Biotechnology - This study investigated the optimization of pea protein (PP) and citrus fiber (CF) contents with the goal of producing a clean-label plant-based stirred soymilk...