Spectroellipsometric Characterization of Multilayer Sol-Gel Fe2O3 Films

Multilayer Fe₂O₃ films were deposited by the sol-gel method on glass substrates using three successive deposition procedures. The films were thermally treated for 1 h at 300°C.The optical and microstructural properties of these films were investigated by spectroscopic ellipsometry (SE) in the 500–1000 nm range. The optical gap was found by fitting the dispersion of the film refractive index (n) with the Wemple-DiDomenico (WDD) formula.The ellipsometric measurements showed also that the Fe₂O₃ films are anisotropic. The birefringence values (n) of the sol-gel films (0.05–0.08) are smaller than the large values of the Fe₂O₃ (which are around 0.28) but increase with the crystalization of the films. AFM mesurements showed that the films treated at 300°C start to crystallize.     

High-Resolution Transmission Electron Microscopy Study of LiNi<Subscript>x</Subscript>Co<Subscript>1−x</Subscript>O<Subscript>2</Subscript> Synthesized by Unconventional Methods

Single phase LiNi_xCo_1–xO₂ (x=0.3) with fine particles were prepared by two low-temperature methods: the modified Pechini sol-gel method and the Self-Propagating Combustion Synthesis (SPCS). It was found that bulk quantities of nano-sized particles of layered LiNi_xCo_1–xO₂ could be obtained at temperatures below 400°C by these solutions technique. The synthesized products were characterized by structural (XRD) and thermal (DTA-TG) analyses. HRTEM was used to evaluate the purity and the phase composition of LiNi_xCo_1–xO₂. Lattice plane images give information about crystal structure and SAED patterns help us to identify the phase. Nano-crystals were obtained with minimum mean diameter about 5nm for both methods.     

Polarization quantum beat spectroscopy of HCF(A1A"). I. 19F and 1H hyperfine structure and Zeeman effect

To further investigate the (19)F and (1)H nuclear hyperfine structure and Zeeman effect in the simplest singlet carbene, HCF, we recorded polarization quantum beat spectra (QBS) of the pure bending levels 2(0) (n) with n = 0-7 and combination bands 1(0) (1)2(0) (n) with n = 1-6 and 2(0) (n)3(0) (1) with n = 0-3 in the HCF A(1)A(")<--X(1)A(') system. The spectra were measured under jet-cooled conditions using a pulsed discharge source, both at zero field and under application of a weak magnetic field (<30 G). Analysis yielded the nuclear spin-rotation constants C(aa) and weak field Lande g(aa) factors. Consistent with a two-state model, the majority of observed vibrational levels exhibit a linear correlation of C(aa) and g(aa), and our analysis yielded effective (a) hyperfine constants for the (19)F and (1)H nuclei (in MHz) of 728(23) and 55(2), respectively. The latter was determined here owing to the high resolving power of QBS. The vibrational state selectivity of the (19)F hyperfine constants is discussed, and we suggest that the underlying Renner-Teller interaction may play an important role.     

A convenient and simple procedure for the preparation of nitrate esters from alcohols employing LiNO3/(CF3CO)2O

Alcohols in small peptides, monosaccharides and steroids (12 examples) are conveniently transformed to their corresponding nitrate esters upon treatment with an acetonitrile solution of LiNO₃ and trifluoroacetic anhydride. The in situ formed mixed anhydride (CF₃COONO₂) is proposed to be the reactive nitration reagent.     

Polarization quantum beat spectroscopy of HCF(A1A"). II. Renner-Teller and spin-orbit mixing in the simplest singlet carbene

To further investigate the Renner-Teller (RT) effect and spin-orbit mixing in the A(1)A(")<--X(1)A(') system of the simplest singlet carbene, HCF, we report a detailed analysis of the K(a) = 1<--0 subband of 2(0) (4) using polarization quantum beat spectroscopy in combination with fluorescence excitation spectroscopy and lifetime measurements. This subband is perturbed both by RT and spin-orbit interactions, which are clearly differentiated due to the order-of-magnitude difference in matrix elements. We show that RT induced mixing with a high vibrational level of X(1)A(') leads to a splitting of this subband, and while the higher energy member is rotationally unperturbed, every line in the lower energy member is perturbed by spin-orbit mixing with background levels of a(3)A("), as evidenced by large (19)F and (1)H hyperfine constants and Lande g factors. In contrast, the higher energy subband exhibits very small Lande g factors and hyperfine constants, which is explained within a model that incorporates only the A(1)A(")-X(1)A(') interaction. We thus demonstrate that polarization quantum beat spectra provides efficient discrimination between RT and spin-orbit interactions. Analysis of the lower energy subband in concert with ab initio electronic structure calculations has yielded the first information on the (19)F and (1)H hyperfine structure of the a(3)A(") state and the magnitude of the spin-orbit matrix elements.     

Application of TLC and GC—MS to the Detection of Capsaicin from Hot Peppers (Capsicum annuum)

JPC – Journal of Planar Chromatography – Modern TLC - Capsaicin was extracted from red hot pepper (Capsicum annuum) fruits and from commercial red hot pepper powder and separated on...     

Investigation of the hydration process in 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-plasticizer-H(2)O systems by X-ray diffraction

The development of the hydration process in 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system is studied by X-ray diffraction in the presence of varying contents of new plasticizer admixtures belonging to the lignosulphonates class (calcium lignosuphonate-LSC) and condensates melamine formaldehyde sulfonated class-MSF (VIMC-11). The plasticizer admixtures were added in proportion of 0.1-1% solid substance. The influence of the plasticizer admixtures on the hydration process with increasing time is observed and it is shown to depend on the nature and content of the admixtures and the reaction time. The strong adsorption of admixtures on the surfaces on the anhydrous or partially hydrated particles of the system can explain the influence of the admixtures upon the kinetics of the hydration process retardation or acceleration. These plasticizer admixtures influence also the evolution of the hydrated compounds and forming of the hardening structure in the 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system; their proportion in the system and the considered length of hardening are correlated. In the 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system there are two different influences of the plasticizer admixtures upon the hydration process. One is a delaying action, as a result of plasticizer adsorption on the surface of the anhydrous and hydrated compound particles and another one is the intensifying action due to the stronger dispersion of the particles in aqueous medium.     

The effect of the nanocarbon structures from laser pyrolysis on microorganisms evolution

The carbon nanoparticles existing in environment are an important factor on healthy either by their toxicity or by interaction with pathogen microorganisms, which can make them more resistant or induce a specific mutagenesis. To understand the role of the nanocarbon particles, a series of carbon nanopowders was synthesized by gas-phase laser pyrolysis from different hydrocarbon-based mixture and used to design cell culture media for Escherichia coli and Staphylococcus aureus. The microorganisms, grown in a given incubation time, were investigated by fluorescent markers (water soluble quantum dots). We report that structure and properties of the nanocarbons influence the behaviour of the aerobic microorganisms. We show that carbon nanopowders are oxygen supplier for microorganisms and, at the same time, due to the presence of polyaromatics or heterogeneous atoms existent in the reactive gas mixture, could have an inhibition/poisoning effect.