Gliadin matrices for microencapsulation processes by simple coacervation method

The aim of this study was to use a vegetal protein (gliadin) as a wall-forming component to produce microcapsules. The microencapsulation technique employed was the simple coacervation method and the encapsulated product was a non-food oil, hexadecane. Hexadecane was emulsified by a gliadin solution and the coacervation phenomena induced by adding a salt-solution in the continuous phase of the emulsion containing gliadin. The study of the coacervation conditions has shown that the richer in protein the continuous phase, the smaller the quantity of salt required. The main problem of the microencapsulation process by salting-out was to control the capsule size and the agglomeration of the capsules. This study succeeded in preventing the agglomeration phenomenon by adjusting the kinetics of the salt addition. When the feed rate of salt solution was very slow, this aggregation was considerably decreased. The suitable quantity of cross-linker (glutaraldehyde) to harden the microcapsules was determined by an electrophoresis method. The effect of different process parameters (gliadin concentration, quantity and addition kinetics of the coacervation agent, cross-linker concentration) was studied with regard to the final microcapsule characteristics (shape, size, composition, and mechanical resistance evaluated by a centrifugation test).

Influence of flow patterns on chromatographic efficiency in centrifugal partition chromatography

Visualization of flow patterns in centrifugal partition chromatography (CPC) was performed with an asynchronous camera and a stroboscope triggered by the CPC rotor, allowing a channel to be selected and observed regardless of rotational speed. Three main types of flow states were noted as a function of rotational speed and flow-rate: jets stuck along channel walls, broken jets and atomization. Our observations emphasize the importance of Coriolis force on flow shape. Chromatographic efficiency was related to the dispersion of the mobile phase in the stationary phase.

Double Resonance Sub-Doppler Study of the Allowed and DeltaK = -3 Forbidden Q(3, 3) Transitions to the nu2 Vibrational State of 14NH3

The IR-IR sub-Doppler double resonance and standard saturation sideband spectroscopy have been used to measure the allowed and Deltak = -3 forbidden transitions to the nu2 vibrational level of 14NH3. The IR-IR double resonance technique has made it possible to observe quadrupole hyperfine structures which correspond to the sums as well as differences of the -3Q(3, 3) and Q(3, 3) hyperfine components. The "sum" and "difference" double resonance frequencies have been measured with accuracy better than 30 and 5 kHz, respectively. In addition to this, the hyperfine structure of the allowed Q(3, 3) transition has been independently measured using the "standard" saturation sideband spectroscopy with accuracy better than 15 kHz. A simultaneous analysis of all measured data provides an improved set of effective nuclear quadrupole and spin-rotation parameters for the excited nu2 vibrational state and frequencies of the "pure" rotation-vibration transitions deperturbed from the hyperfine effects at the experimental sample pressure of about 3 mTorr, including a very precise zero pressure value of the "forbidden" spacing between energies of the nu2 ||s, J = 3, K = 3> and ||s, J = 3, K = 0> pure rotational levels of 2883.6795(19) MHz [0.096189194(63) cm-1]. Copyright 1998 Academic Press.

Doppler-free two-photon spectrum of SF(6) for metrological purposes

We report on our systematic investigation of strong Doppler-free two-photon absorption in the middle infrared. The absorption frequencies for two counterpropagating waves of identical frequencies are predicted. Five of these transitions were observed with sub-Doppler resolution with a sideband CO(2) laser and were measured with 10-kHz accuracy. Knowledge of these strong two-photon absorptions frequencies will allow the improvement of secondary frequency standards in the infrared.

Saturation Sideband CO2 Laser Spectroscopy of the Overtone Band 2nu2 and Its Hot Band 3nu2-nu2 of Carbonyl Sulfide

The saturation spectra of the 2nu2 and the 3nu2-nu2 bands of carbonyl sulfide have been studied using a CO2 laser sideband spectrometer. The frequency of 20 absorption lines has been determined with an accuracy of 20 kHz. These data have been included in a global rovibrational analysis including all the other data available on 16O12C32S. We list an improved set of standard frequencies at the 10(-6) cm-1 level. Copyright 1998 Academic Press.

Subdoppler Study of the nu7 Band of C2H4 with a CO2 Laser Sideband Spectrometer

The saturation spectrum of ethylene has been studied between 900 and 1100 cm-1 with the sub-Doppler sideband spectrometer of Lille. Two hundred absorption lines have been recorded with an absolute accuracy of approximately 15 kHz. On the basis of these accurate data, a new global analysis of the GS and of the nu7, nu10, and nu4 upper states was achieved taking into account the Coriolis interactions up to the third order. A statistical agreement is obtained with all experimental data with an estimated standard deviation equal to 0.825. The spectra of ethylene between 900 and 1100 cm-1 become very good wavenumber standards with an absolute accuracy of 10(-6) cm-1. Copyright 1998 Academic Press.