Gold Nanoparticles Supported on the Periodic Mesoporous Organosilicas as Efficient and Reusable Catalyst for Room Temperature Aerobic Oxidation of Alcohols

Gold nanoparticles supported on the channels of a bifunctional periodic mesoporous organosilica, were found to be a highly efficient catalyst system for the aerobic oxidation of various types of alcohols into their corresponding aldehydes and ketones at room temperature. The catalyst showed no significant loss of efficiency for the aerobic oxidation of benzyl alcohol to give benzaldehyde after 7 reaction cycles.     

Mineral recovery from inland reverse osmosis concentrate using isothermal evaporation

Mineral recovery from reverse osmosis (RO) concentrate after concentration by a secondary sea water-type RO system with lime–soda pretreatment was the focus of this study. Lime–soda pretreatment removed Ca, Mg and Si allowing for the application of sea water-type RO resulting in a concentrate composed of sodium, potassium, sulfate and chloride. The overall objective was reduction in concentrate volume that will require disposal by evaporation while producing by-products with potential resale value. Thermodynamic phase equilibrium calculations using Pitzer’s correlations for 25 °C, accurately predicted the solubility and evaporation path of the sodium sulfate minerals as potential by-products. Bench-scale evaporation experiments verified the model predictions and indicated that 81–88% of the sodium sulfate by-products were Na₂SO₄.     

Behavior of polymer concrete beam/pile confined with CFRP sleeves

This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity.     

Tailoring the Thermal and Mechanical Properties of Graphene Film by Structural Engineering

Due to substantial phonon scattering induced by various structural defects, the in‐plane thermal conductivity (K) of graphene films (GFs) is still inferior to the commercial pyrolytic graphite sheet (PGS). Here, the problem is solved by engineering the structures of GFs in the aspects of grain size, film alignment, and thickness, and interlayer binding energy. The maximum K of GFs reaches to 3200 W m^?1 K^?1 and outperforms PGS by 60%. The superior K of GFs is strongly related to its large and intact grains, which are over four times larger than the best PGS. The large smooth features about 11 µm and good layer alignment of GFs also benefit on reducing phonon scattering induced by wrinkles/defects. In addition, the presence of substantial turbostratic‐stacking graphene is found up to 37% in thin GFs. The lacking of order in turbostratic‐stacking graphene leads to very weak interlayer binding energy, which can significantly decrease the phonon interfacial scattering. The GFs also demonstrate excellent flexibility and high tensile strength, which is about three times higher than PGS. Therefore, GFs with optimized structures and properties show great potentials in thermal management of form‐factor‐driven electronics and other high‐power‐driven systems.     

Superabsorbent polymer composites: does clay always improve properties?

Clay is frequently incorporated to many materials including superabsorbent polymers (SAPs) to improve their properties. Superior properties have been reported for the SAP composite (SAPC) materials comparing to their clay-free counterparts. However, study of the effect of clay on some of very important requirements of superabsorbents, particularly the residual monomer (RM), has been unnoticed in the academic literature. Here, we report preparation of a series of SAPCs via a conventional solution polymerization of partially neutralized acrylic acid in the presence of common MMT clay (Na-montmorillonite). The products were characterized by FTIR spectroscopy, differential scanning calorimetry, thermogravimetric, thermomechanical, and rheometrical analyses. The RM content of the samples was determined by high performance liquid chromatography. It was found that the clay had unfavorable effects on the crosslinking polymerization process. This fact was observed as declining mechanical strength of the SAPCs in both dried and swollen states, increased swelling capacity, decreased gel fraction, and increased RM content. For instance, RM of clay-free sample was 740 ppm which was continuously increased with level of the clay incorporated. It surprisingly reached to ~34,000 ppm at clay content of 12%. The undesirable function of clay was attributed to inactivation and barrier effects of clay incorporated to the polymerization medium. These unwanted effects were more pronounced at high clay content. However, overall thermostability of SAPCs was improved comparing to the non-composite counterpart. It was concluded that such conventionally prepared SAPCs, in spite of the previously reported claims, could not be suitable candidates for hygienic applications, particularly those prepared with high clay percentages.     

Red tide detection in the Strait of Hormuz (east of the Persian Gulf) using MODIS fluorescence data

A monstrous red tide appeared on October 2008 and expanded to the west on November 2008 off the Iranian coasts in the Hormuz Strait (east of the Persian Gulf). MODIS satellite data, hydrographic and bio-optical field measurements were used to detect the red tide. MODIS fluorescence line height (FLH in w m^?2 μm^?1 sr^?1) data showed the highest correlation with near-concurrent in situ chlorophyll concentration of 0.74 (100(FLH))^1.23 (r?=?0.9, n?=?44). In contrast, the band-ratio Chlorophyll product of MODIS showed more inconsistency with in situ chlorophyll data due to the interference of other water constituents. High FLH value patches >0.18 were confirmed to be located at the medium to high (10⁴–10⁶ cells l^?1) concentrations of Cochlodinium polykrikoides, and also showed a chlorophyll anomaly >1 mg m^?3, which means the potential of red tide occurrences. The FLH imagery also showed that the bloom started in early September along Bandar-Abbas port, and developed and moved to the west along the coastal regions. The results revealed that MODIS FLH and enhanced RGB (ERGB) imagery plus in situ data are adequate tools for red tide monitoring.     

Sense of Immersion in Computer Games Using Single and Stereoscopic Augmented Reality

As a novel interaction and presentation technology, Augmented Reality (AR) has been widely used in education, tourism, entertainment, psychology, and many other applications. In the game industry, this revolutionary technology has introduced a new form of interaction between players and the gaming environment. In this article, we aim to find if exploiting AR in computer games can enhance the sense of immersion, and consequently, satisfying the players. To this end, a mobile game called Ladybug is implemented using three different techniques including the regular virtual reality (VR) camera, single AR camera, and stereoscopic AR camera. The results of a comprehensive user study on these techniques showed that the single AR camera and stereoscopic AR camera can result in more sense of immersion in players in comparison to the VR camera. However, the hypothesis that the stereoscopic AR results in more sense of presence in comparison to the single AR camera is rejected. On the other hand, our findings show that the AR stereoscopic camera can lead to a better emotional involvement and enjoyment in comparison to the single AR camera and VR camera.     

Electromagnetic THz Radiation Modeling by DPSM

THz or T-ray imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. In order to understand the interaction between the T-ray electromagnetic waves and dielectric media a reliable model of electromagnetic wave propagation through dielectric materials must be developed. A recently developed semi-analytical method called the distributed point source method (DPSM) is extended to model electromagnetic wave propagation in THz range. Since T-ray signals generated by emitters or sources are close to Gaussian beams, the DPSM modeling is carried out for Gaussian beams generated by finite sized emitters. The DPSM generated results are compared with the analytical and experimental results. T-ray propagation in layered structures in absence of any anomaly and the interaction between the Gaussian beam and the spherical scatterer are also investigated.     

Chitosan‐modified nanoclay–poly(AMPS) nanocomposite hydrogels with improved gel strength

BACKGROUND: Making (nano)composite structures is one of the efficient approaches for strengthening hydrogels extended in recent years. The present paper deals with the synthesis and properties of novel nanocomposite hydrogels based on 2‐acrylamido‐2‐methylpropane‐1‐sulfonic acid (AMPS). Initially, a bio‐modified clay, chitosan‐intercalated montmorillonite (chitoMMT), was prepared. Then, this was incorporated into the polymerization of AMPS in the presence of a macro‐crosslinker, i.e. poly(ethylene glycol) dimethacrylate, to yield super‐swelling nanocomposite hydrogels. The swelling capacity as well as some structural, rheological and thermomechanical properties of the hydrogels were studied and compared with those of the clay‐free counterpart. RESULTS: ChitoMMT exhibited no toxicity, which was confirmed using cell‐culture testing. A chitoMMT content of ca 6% was found to be the most favourable content of the bio‐modified clay for achieving a product with improved properties (i.e. the highest gel content, the highest gel strength and optimal thermal stability). Based on a dynamic mechanical thermal analysis study, an increased glass transition temperature (98.2 °C) and improved rubbery modulus (up to 238% higher than that of the clay‐free counterpart) were recorded. Thermogravimetric analysis verified that the thermal stability of nanocomposite samples was higher than that of clay‐free samples. CONCLUSION: Owing to the non‐toxicity of the incorporated chitoMMT, the strengthened hydrogels may be considered as potential candidates for bio‐applications. Copyright © 2009 Society of Chemical Industry