Soret and Dufour effects on convective instabilities in binary nanofluids for absorption application

Thermodiffusion (Soret effect) and diffusionthermo (Dufour effect) effects on convective instabilities in nanofluids have been theoretically investigated. Thermodiffusion implies that mass diffusion is induced by thermal gradient, which is so-called the Soret effect. Diffusionthermo implies that heat transfer is induced by concentration gradient, which is so-called the Dufour effect. By using the linear stability theory under one-fluid model, a characteristic dimensionless parameter was newly obtained. From the instability analysis with given conditions, it is found that the convective motion in nanofluids sets in easily as the Soret and Dufour effects and the initial concentration of nanoparticles increase.     

Enhanced anti-cancer effect of 5-fluorouracil loaded into thermo-responsive conjugated linoleic acid-incorporated poloxamer hydrogel on metastatic colon cancer models

Conjugated linoleic acid-coupled Pluronic F127 (Plu-CLA) is an effective drug delivery system with numerous advantages and anti-cancer activity. 5-FU administered in Plu-CLA hydrogel (P-FU) led to the significant enhancement of tumor growth suppression and cellular apoptosis. Moreover, growth of hepatic and intraperitoneal metastases in vivo was significantly reduced in mice treated with P-FU. Therefore, Plu-CLA could be a potential intraperitoneal carrier for hydrophilic 5-FU for the effective treatment of metastatic colon cancer.     

Influence of external electric field on optical properties of Dy3+ embedded in chalcogenide glass modified with Ga and CsBr

In sulfur-based chalcogenide glass, i.e., a covalent amorphous solid, the addition of a small amount of Ga + CsBr switches the nearest neighbors of the Dy3+ dopant from S to Br, which results in significant enhancement in the lifetime of the excited 4f configurational states of Dy3+. The chemical preference between [GaS3Br]- and Dy3+ alters only the local structures of the involved rare earth ion. This atomic restructuring occurs spontaneously at a nanoscale during the melt-quenching process, without the need for further heat treatment, and thus improves the luminescence properties of the activator while keeping the thermal and mechanical properties of the parent host material unchanged. In this study, it is experimentally verified that externally applied DC electric fields can further tune the oscillator strengths of Dy3+ in Ge-S glass that contains Ga + CsBr. This experimental finding proves that mass transports driven by electric fields influence the optical properties of rare earth doped in the chalcogenide glass that is compositionally engineered in this study.     

A Novel Ternary CDMA Code for TPSK Modulation Scheme

In code division multiple access (CDMA), two or more chips are grouped together to form symbols and each symbol is transmitted during the symbol period. The phase shift keying (PSK) modulation techniques map the digital baseband data into two or more possible signals by varying the phase of a radio frequency (RF) carrier. The recently proposed PSK scheme called ternary PSK (TPSK) scheme can convey three possible symbols. In this paper, a novel ternary based CDMA sequence so-called large area synchronous even ternary (LAS-ET) sequence is introduced to increase spectrum efficiency in TPSK scheme. Its sequence duty ratio and cross-correlation are analyzed. The performance analysis of this sequence is compared with the large area synchronous (LAS) sequence in term of symbol error rate and chip error rate (CER) over various channel models. It is shown that TPSK scheme in LAS-ET sequence outperforms LAS sequence in terms of CER evaluation. At the same time, the spectrum efficiency is doubled when a pair of chips in LAS-ET sequence is mapped into one symbol.     

Bridge length effect of new dinuclear constrained geometry catalysts on controlling the polymerization behaviors of ethylene/styrene copolymerization

According to the observable evidence from ¹H and ¹³C nuclear magnetic resonance and mass spectrometry, new dinuclear constrained geometry catalysts (DCGCs) with a structure of [{Ti(η⁵:η¹-(C₉H₅)Si(CH₃)₂N^tBu)Cl₂(CH₂)_n}₂(C₆H₄)] [n = 0 (10), n = 1 (11), n = 2 (12)] were synthesized successfully. Copolymerization of ethylene and styrene were tested by using three new DCGCs and Dow CGC. The catalyst activity, the molecular weight (MW) and styrene content of the copolymers were sharply improved as the bridge structure was transformed from para-phenyl (10) to para-xylyl (11) and para-diethylenephenyl (12). The activity of 11 and 12 was about four to five times greater than that of 10 regardless of the polymerization conditions. In addition, the capability to form high MW polymers increased in the order of Dow CGC ≈ 10 < 11 < 12. The styrene contents in copolymers generated by 11 and 12 were higher than those of 10.     

Chipping minimization in drilling ceramic materials with rotary ultrasonic machining

Ultrasonic machining (USM) has been considered as a new cutting technology that does not rely on the conductance of the workpiece. USM presents no heating or electrochemical effects, with low surface damage and small residual stresses on workpiece material, such as glass, ceramics, and others; therefore, it is used to drill microholes in brittle materials. However, this process is very slow and tool wear dependent, so the entire process has low efficiency. Therefore, to increase microhole drilling productivity or hole quality, rotary ultrasonic machining (RUM) is considered as a strong alternative to USM. RUM, which presents ultrasonic axial vibration with tool rotation, is an effective solution for improving cutting speed, precision, tool wear, and other machining responses beyond those of the USM. This study aims to reduce the microchipping or cracking at the exit of the hole, which inevitably occurs when brittle materials are drilled, with consideration of tool wear. To this end, response surface analysis and desirability functions are used for experimental optimization. The experimental results showed that the proposed RUM scheme is suitable for microhole drilling.     

Effect of urea,NH4OH,and DCCA on texture properties of alumina prepared by ultrasonic spray pyrolysis

Mesoporous alumina particles were prepared by using a spray pyrolysis process of aluminum nitrate precursor using cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. The effects of ammonium hydroxide, urea, and drying-control-chemical agent (DCCA) on the particle morphology and pore properties of alumina particles were studied by means of N₂ physical adsorption, transmission electron microscopy (TEM), and small-angle X-ray diffraction (SAXS) analysis. It was found that using urea rather than NH₄OH in the spray pyrolysis is effective to increase the surface area of alumina with well-organized uniform pores. The addition of NH₄OH led to decrease the surface area as well as the pore regularity. Using both DCCA and urea was a helpful way to improve the surface area, the pore volume, and the pore size distribution of alumina synthesized by spray pyrolysis. The prepared alumina particles had a broad SAXS peak without further reflection peaks indicating hexagonal or cubic symmetry. According to TEM analysis, a long-range ordering of mesopores was not observed. More details on the texture properties and the morphology of alumina particles prepared by with changing the kinds of additives in spray solution were discussed.     

Label-free detection of melittin binding to a membrane using electrochemical-localized surface plasmon resonance

Localized surface plasmon resonance (LSPR) and electrochemistry measurements connecting to core-shell structure nanoparticle are successfully exploited in a simultaneous detectable scheme. In this work, the surface plasmon band characterizations of this nanostructure type are initially examined by controlling the core size of the silica nanoparticle and shell thickness of the deposited gold. These results clearly show that when the shell thickness is increased, keeping the core size constant, the peak wavelength of the LSPR spectra is shifted to a shorter wavelength and the maximum of peak intensity is achieved at a particular shell thickness. On the basis of this structure, we present a membrane-based nanosensor for optically detecting the binding of peptide toxin melittin to hybrid bilayer membrane (HBM) and electrochemically assessing its membrane-disturbing properties as a function of concentrations. It will open up the way to detect functionally similar protein toxins and other membrane-targeting peptides with the intension of integrating this chip into a microfluid and expanding it into multiarray format.     

Preparation and characterization of polyacrylamide cryogels produced from a high‐molecular‐weight precursor. II. The influence of the molecular weight of the polymeric precursor

Polyacrylamide gels and cryogels were prepared by the crosslinking reaction of polyacrylamide (a polymeric precursor) with glutaric aldehyde (a crosslinking agent) in liquid and moderately frozen aqueous media, respectively. Polymeric precursors of different viscosity‐ averagemolecular weights (0.3, 1, 3, and 9 MDa) were used. The molecular weight of the precursors, as well as the reaction temperature and concentration of the crosslinking agent, exerted a pronounced influence on the efficiency of gelation (gel fraction yield) and on the properties (swelling capability) and structural peculiarities of the resulting gels (reference samples) and cryogels. The highest efficacy was inherent in the cryotropic gelation process when the polymeric precursor had a molecular weight of about 3 MDa, whereas the implementation of polyacrylamides of lower (0.3 or 1 MDa) or higher (9 MDa) molecular weights diminished the gel formation efficiency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008