Long range trace detection in aqueous aerosol using remote filament-induced breakdown spectroscopy

Remote filament induced breakdown spectroscopy (R-FIBS) is used for probing a cloud of microdroplets where table salt has been dissolved. These microdroplets are a good simulant for aerosols. We demonstrated experimentally that R-FIBS can efficiently be used as a ppm-level sensing technique to remotely retrieve the composition of microdroplets in clouds located at a distance. The technique has been successfully tested up to 70 m and, as revealed by extrapolation, showed great potential for kilometer-range application. The proposed technique is sensitive to the solvent as well. For the first time, to the best of our knowledge, four hydrogen bands from the Balmer series were observed in an aqueous microdroplet cloud after H₂O molecules were broken by the light filaments. PACS 42.62.Fi; 92.20.Bk; 95.75.Qr     

Generation of powerful filaments at a long distance using adaptive optics

Because of its extraordinary properties (intensity clamping, white light source, km long plasma channels), filamentation represents an ideal candidate for remote sensing. However, the promising generation of filaments at long distances for such purposes remains an issue.

We propose a specially designed focusing telescope to properly deliver the laser pulses at long distance and generate powerful filaments. The telescope includes a deformable mirror (DM) that corrects the wavefront’s aberrations working in a closed loop system with a wavefront sensor (WFS). Using this setup we are able to generate extraordinarily strong nitrogen signals at a distance as far as 90 m using 40 mJ laser pulses. Compared to the chirped based filament control technique, we believe that an appropriate control of the reservoir like what we have achieved will contribute to reduce the energy of the required laser pulses and at the same time, the cost of the required laser system.     

Experimental study on thermo-physical and rheological properties of stable and green reduced graphene oxide nanofluids: Hydrothermal assisted technique

In this study a dehydration hydrothermal technique has been used to introduce a simple, environmentally friendly and facile method for manufacturing highly dispersed reduced graphene oxide for improving the thermo-physical and rheological properties of heat transfer liquids. The hydrothermal reduction of graphene oxide was verified by various characterizations methods such as UV–visible absorption spectroscopy, Zeta potential, Raman spectroscopy, X-ray photoemission spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. A thorough investigation was conducted on the thermo-physical properties of reduced graphene oxide at concentrations of 0.02, 0.04, 0.06, and 0.08?wt% under different temperatures. Significant improvements in electrical and thermal conductivity were obtained by adding a small amount of hydrothermal-assisted reduced graphene oxide (h-rGO) in the suspension. The viscosity and density remained relatively unchanged with the increase of concentrations where the pH was maintained within the desirable value, despite the fact that no additive was used during the reduction process. It is noteworthy to highlight that the h-rGO aqueous suspensions have shown Newtonian behavior. Results indicated that the h-rGO could be employed as a promising additive for conventional heat transfer liquids for different thermal applications.     

Ce-promoted Mn/Na2WO4/SiO2 catalyst for oxidative coupling of methane at atmospheric pressure

A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressure in a micro-quartz-tube reactor. The catalysts were characterized by X-ray diffraction (XRD), temperature program reduction (TPR) and BET surface area. Ce promoter increased surface area and Na2WO4 species dispersion, which enriched the amount of the surface species. In addition, Ce promoter in...     

Thermogravimetry of deposited caustic soda used as a flame-retardant for cotton fabric

We have investigated the effect of caustic soda as a nondurable finish on the flammability of 100% cotton fabric (plain 180 g m^?2). On the contrary to the mercerization, during the impregnation process, no tension was applied. In order to attain the alkali cellulose onto the fabric, the subsequent neutralization was not followed. Each bunches of fabrics were dipped into individual aqueous solutions of sodium hydroxide, followed by means of squeeze rolls and drying at 110°C. After conditioning nightlong, by using our ‘vertical flame test’ the optimum add-on values to impart flame-retardancy into cotton fabric was determined as 1.3 g sodium hydroxide per 100 g fabric. Thermogravimetry and derivative thermogravimetry (TG/DTG) of pure cotton, treated cotton with sodium hydroxide at its optimum efficiency to impart flame-retardancy into the fabric was fulfilled and the obtained curves were compared and commented. The effectiveness of this hydroxide is attributed to the heat dissipation by the remaining material in the consumed ash. The results obtained are in favour of ‘dust or wall effect theory’ and also gas dilution theory.     

Pressurized fluid extraction of essential oil from Lavandula hybrida using a modified supercritical fluid extractor and a central composite design for optimization

Essential oil components were extracted from lavandin (Lavandula hybrida) flowers using pressurized fluid extraction. A central composite design was used to optimize the effective extraction variables. The chemical composition of extracted samples was analyzed by a gas chromatograph-flame ionization detector column. For achieving 100% extraction yield, the temperature, pressure, extraction time, and the solvent flow rate were adjusted at 90.6°C, 63 bar, 30.4 min, and 0.2 mL/min, respectively. The results showed that pressurized fluid extraction is a practical technique for separation of constituents such as 1,8-cineole (8.1%), linalool (34.1%), linalyl acetate (30.5%), and camphor (7.3%) from lavandin to be applied in the food, fragrance, pharmaceutical, and natural biocides industries.     

DFT investigation for NH3 adsorption behavior on Fe,Ru, and Os-embedded graphitic carbon nitride: promising candidates for ammonia adsorbent

Journal of the Iranian Chemical Society - The adsorption of NH3 molecules on the pristine graphitic carbon nitride (gCN) and TM-embedded gCN systems (TM = Fe, Ru, and Os atoms) was...     

Preparation,mechanical properties,and in vitro biocompatibility of novel nanocomposites based on polyhexamethylene carbonate fumarate and nanohydroxyapatite

In the current study a new biodegradable nanocomposite based on poly hexamethylene carbonate fumarate (PHMCF) and nano‐sized hydroxyapatite (nano‐HA) has been developed. A silane coupling agent γ‐methacryloxypropyltrimethoxy silane, was used to achieve a good interfacial adhesion between nano‐HA and PHMCF matrix. PHMCF with different nano‐HA contents were characterized using dynamical mechanical thermal analysis (DMTA) and hardness test. The effect of frequency on storage modulus, glass transition temperature (T_g) and the damping were investigated. In vitro cytotoxicity and proliferation were performed using G292 cell lines by MTT assay. The addition of nano‐HA resulted in an increment on the storage modulus and decrement on the damping. Along with improvement in mechanical properties of composites, the addition of nano‐HA resulted in enhanced cell proliferation. Following these results, the newly developed nano‐PHMCF composite scaffold may be considered for bone tissue engineering applications. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of polysubstituted 2-azetidinones via in situ generation of a vanillinyl ketene and electrocyclic reaction of the corresponding zwitterionic intermediate

Research on Chemical Intermediates - Highly stereoselective synthesis of polyfunctionalized 2-azetidinones was achieved starting from vanillin as an available natural product. Our approach to these...