Simple adaptation of the technique of immersion calorimetry enables determining both integral and differential adsorption heats as well as the course of the adsorption isotherm of phenol on activated carbon. The innovative aspect of the applied procedure consists in bringing the phenol aqueous solution to contact with the suspension of carbon with water. Thus, the “interfering” heat effect of carbon interaction with water is eliminated, and only the net adsorption heat of phenol is monitored. The value of −52.5 kJ mol−1 was ascertained as the molar differential adsorption heat at the low surface coverage (cca 0.2 mmol g−1) of the sample of microporous carbon. As the adsorption process continues, for adsorption uptakes exceeding the value of about 1 mmol g−1, molar differential adsorption heats appear to be established at a level of about −20 + 5 kJ mol−1.
A konfigurációs mechanika – melyet első kutatója tiszteletére Eshelby-féle mechanikának is neveznek – a kontinuummechanika egyre fontosabbá váló területe. A koncepció maga nem tekinthető új keletűnek, mivel Eshelby munkásságában az 1950-es évek elejétől találkozhatunk a témával. Mindazonáltal a numerikus módszerek elterjedése miatt és a nagy számítási kapacitással rendelkező számítástechnikai eszközök megjelenésével új lehetőségek nyíltak meg a tématerület gyakorlati alkalmazásait illetően. Az Eshelby által bevezetett feszültségtenzor az anyagokban található inhomogenitások hatásainak vizsgálatát teszi lehetővé. Az abból származtatott úgynevezett konfigurációs erő a mechanika számos területén kínál komoly felhasználási lehetőségeket. Jelen cikk témája a konfigurációs mechanika elméletének rövid bemutatása, majd a jelenleg leginkább elterjedt, a konfigurációs erő numerikus számításán alapuló alkalmazások bemutatása. Ez három nagy területet foglal magába. A konfigurációs erő egyik leginkább kecsegtető alkalmazási lehetősége a törésmechanikai problémák területén jelentkezik. Másik nagy terület az alak- és szerkezeti optimálás. Végezetül egy újszerű és eredményesen alkalmazható eljárás került bemutatásra, mely a numerikus megoldás pontosítását célozza a végeselem háló kezdeti konfigurációjának optimalizálásán keresztül. Ez utóbbi felhasználási terület alkalmazását néhány egyszerű tesztpélda is szemlélteti.
Authors:F. De Corte, L. Moens, K. Sordo-El Hammami, A. Simonits and J. Hoste
Some methods described in the literature for the determination of α in the 1/E1+α epithermal neutron spectrum are critically reviewed with respect to their accuracy. The multi resonance—detector method with
Cd-covered irradiations, as used by SCHUMANN and ALBERT, is generalized by subtracting the epithermal 1/v-tail and by introducing
the effective resonance energy, as defined by RYVES. The two-detector method of RYVES is modified by using Cd-ratio measurements,
thus eliminating the introduction of systematic errors due to the inaccuracy of absolute nuclear data. The adapted methods
are applied in channel 15 of the Thetis reactor (Gent).
Authors:Alexandre G. S. Prado, André L. F. Santos, Carolina P. Pedroso, Thiago O. Carvalho, Lilian R. Braga and Sheila M. Evangelista
Chitosan is a biodegradable natural polymer with great potential for pharmaceutical applications due to its biocompatibility, high charge density, and non-toxicity. In this study, chitosan microspheres were successfully prepared by an adapted method of coagulation/dispersion. The degree of deacetylation of chitosan powder was obtained by NMR 1H and FTIR techniques. Chitosan powder and chitosan microspheres were characterized by BET surface area and scanning electron microscopy (SEM). The interactions among the chitosan microspheres and the vitamins A and E were characterized by FTIR. In order to evaluate the ability of interaction of vitamin A and vitamin E with the chitosan microspheres, the thermodynamic parameters were followed by calorimetric titration. Different experimental approaches were applied, such as adsorption isotherms, kinetics and thermodynamics studies. The obtained results showed that the interactions of chitosan microspheres with the vitamins were spontaneous, enthalpically and entropically favorable, indicating that the chitosan microspheres can be used with success in the controlled release of these vitamins.
Authors:G. Kayfus, T. Boothe, J. Campbell, R. Finn and A. Gilson
Because of the cost and limited availability of isotopically enriched thallium (>92%203Tl), its use in the203Tl(p, 3n)201Pb nuclear reaction necessitates chemical recovery. An adaptive method has been developed and evaluated. After the separation
of201Pb, the203Tl(I) is oxidized to203Tl(III) by Cl2, Br2 or [Fe(CN)6]−2, precipitated as Tl(OH)3 with NaOH and subsequently converted to Tl2O3 by heating. Due to potential loss during recovery, the solubilities of Tl(OH)3 and Tl2O3 in aqueous solution as a function of pH have been studied using the internal tracer202Tl (T=12.2d), produced during cyclotron irradiation. Effective solubility product constants have been determined to be 5.4·10−48 and 2.5·10−47 for Tl(OH)3 and Tl2O3, respectively.
Antibiotic extraction from solid matrices is generally complicated unlike aqueous phases. Consequently, increasing the extraction efficiency of antibiotics from solid matrices has received a great concern. Therefore, the main objective of this study was to determine three macrolide antibiotics; tylosin (TYL), spiramycin (SPIR), and erythromycin (ERY) in buffaloes’ meat using the recommended method of thin-layer chromatography-bioautography (TLC-B) after some modifications. Antibiotics were extracted by 0.2% metaphosphoric acid-methanol (6:4, 7p/7p), and then the extracts were cleaned up using an Oasis HLB cartridges (200 mg). The recovery ratios at 0.5, 1, and 2 maximum residue limits (MRLs) with high precision were 84.19–92.22%, 83.09–89.42%, and 84.89–90.28%, respectively. The detection limits were 12, 45, and 2 ng g−1 for TYL, SPIR, and ERY, respectively. Forty-five samples of Egyptian buffaloes’ meat were analyzed using the adapted method. Only 9 and 5 samples out of the 45 samples were positive for TYL and ERY, respectively, with mean concentrations of 42.59 and 31.21 (ng g−1) which were lower than the permitted MRLs recommended by the European community.
The crystallisation properties of a mixture of triacylglycerols (TG), cocoa butter (CB) 75%/miglyol 25%, were investigated
on cooling at 0.5 °C/min using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The influence of (i) the
dispersion of TG within nanoparticles stabilised by proteins, and of (ii) the presence of polar lipids were characterised.
In bulk, crystallisation of TG successively occurred with a α 2L (49.3 Å) structure, then the formation of longitudinal stackings
of 44.5 and 34.5 Å of β′ form was interpreted as co-crystallisation of TG from CB and miglyol. The dispersion of TG in nanoparticles
of about 400 nm induced a higher supercooling and changed their crystallisation properties. The formation of α 49.2 Å and
β′ 45 Å structures corresponded to the segregation of TG from CB in solid phases while TG from miglyol remained liquid. Phospholipids
with saturated fatty acid chains affected the thermal properties of TG, which demonstrated their localisation at the surface
of the nanoparticles. DSC and XRD revealed to be very sensitive and adapted methods to increase the knowledge about the mechanisms
of crystallisation in emulsion.
and fractional order controller. For the aforementioned cases, a comparison is done by applying the MRAC (Model Reference Adaptive Control) theory, which is the most known and easy to apply adaptivemethod, to show the benefits of using the fractional
Authors:Yi Ying Cheok, Suat Moi Puah, Kek Heng Chua and Jin Ai Mary Anne Tan
species, and they were selected for molecular analysis. DNA extraction An in-house-adaptedmethod for DNA extraction was performed ( Puah et al., 2017 ). A total of 2 mL of the overnight bacterial culture was pelleted and washed vigorously with sterile