Preparation and characterization by infrared emission spectroscopy and applications of new mineral-based composite materials of biomedical interest

New composite materials based on clay minerals had been prepared by reductive calcination. These materials exhibit very strong infrared (IR) emission at quite low temperatures. The structural properties and emission capabilities of the new materials have been studied by various theoretical and experimental methods. In addition, a brief overview of the medical and other practical applications of IR-emitting materials is presented. The basic principles of IR emission spectroscopy are discussed with special respect to low temperatures (close to human-body temperature). Furthermore, DFT calculations on a kaolinite structure of chemical composition of [Al₄Si₄ O₈(OH)₁₆]^4? have been performed. The calculated bond distances and IR spectrum are in good agreement with experimental observations. Structural and compositional characterization of the new composite materials have been performed by various structural analytical methods. An interesting effect on the IR phosphorescence of composite samples has been established. After 2 hours of IR light exposure at room temperature from the FT-IR spectrometer, the composite materials exhibited enhanced emission of IR radiation with relaxation time about 40 min. Finally, two practical applications of the composites have been investigated, namely polyamide-based fabrics and rubber preservatives.     

Optical and electrical characterization of aluminium doped ZnO layers

Al doped ZnO (ZAO) thin films (with Al-doping levels 2 at.%) were deposited at different deposition parameters on silicon substrate by reactive magnetron sputtering for solar cell contacts, and samples were investigated by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and spectroscopic ellipsometry (SE). Specific resistances were measured by the well known 4-pin method. Well visible columnar structure and in most cases voided other regions were observed at the grain boundaries by TEM. EELS measurements were carried out to characterize the grain boundaries, and the results show spacing voids between columnar grains at samples with high specific resistance, while no spacing voids were observed at highly conductive samples. SE measurements were evaluated by using the analytical expression suggested by Yoshikawa and Adachi [H. Yoshikawa, S. Adachi, Japanese Journal of Applied Physics 36 (1997) 6237], and the results show correlation between specific resistance and band gap energy and direct exciton strength parameter.     

Acoustically assisted removal of nitrogen oxide from high temperature flue gas

The present study focuses on a possibility for improving NO removal efficiency from flue gas by application of powerful sound waves. The sound waves (frequency 6.9-17.2kHz, intensity 144-160dB) are propagated from Hartmann sound generators to a preheated graphite disk inside a vertical reaction tube (height 1.8m, I.D. 105mm). An Ar-NO synthetic mixture (NO 911-934ppm) is blown onto the disk surface to perform reactions in the system C-NO. It is found that the NO reduction rate can be significantly enhanced by the sound waves but the enhancement effect is dependent on the sound frequency, intensity and temperature of disk surface. The better effects are obtained at a temperature of 973K and sound frequencies between 9.6 and 12.4kHz. Under these conditions, the sound application results in 3-5-fold enhancement of NO reduction rate. The obtained effects are explained in terms of gas-phase mass transfer controlling mechanism and of near surface turbulent diffusivity.     

Isolation and synthesis of 2-chloro-10-α-hydroxynaltrexone, a new naltrexone degradant

The putative structure of a new degradant from REVIA® tablets was assigned 2-chloro-10-α-hydroxynaltrexone 2. A route for the independent synthesis was developed wherein a N,N-diethylcarbamate derivative directed an ortho-metallation of the naltrexone nucleus, leading to the desired 2-chloro functionality. Oxidation of the 10-position, followed by deprotection provided 2, which was identical in all respects to the original isolate.     

Search for a fourth-generation quark more massive than the Z0 boson in p&pmacr; collisions at radicals = 1.8 TeV

We present the results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in sqrt[s] = 1.8 TeV p&pmacr; collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b(')-->bZ(0) and that the b(') mass is greater than m(Z)+m(b). We studied the decay mode b(')b(');-->Z(0)Z(0)b&bmacr; where one Z0 decays into e(+)e(-) or &mgr;(+)&mgr;(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(p&pmacr;-->b(')b(');)x[B(b(')-->bZ(0))](2) is established as a function of the b(') mass. We exclude at 95% confidence level a b(') quark with mass between 100 and 199 GeV/c(2) for B(b(')-->bZ(0)) = 100%.     

X-Ray waveguiding studies of ordering phenomena in confined fluids

We have determined the structure of a colloidal fluid confined in a gap between two walls by making use of the waveguiding properties of the gap at x-ray wavelengths. The method is based on an analysis of the coupling of waveguide modes induced by the density variations in the confined fluid. Studies on suspensions confined within gaps of a few hundred nanometers showed strongly selective mode coupling effects, indicative of an ordering of the colloidal particles in layers parallel to the confining walls.