Solubility study and intensification of extraction of phenolic and anthocyanin compounds from Oryza sativa L. ‘Violet Nori’

Oryza sativa L. ‘Violet Nori’ is an Italian cultivar of spontaneous growing aromatic purple rice which is particularly rich in polyphenolic compounds, especially anthocyanins, conferring it an excellent antioxidant capacity. The present study aimed at increasing the extraction yields of its antioxidant compounds with green strategies and it is divided into two steps. The first step concerned a solubility study of the targeted polyphenols in different ethanol:water mixtures by means of a theoretical prediction method, using the simulation program COSMO-RS, and the subsequently confirmation of the computational results by practical experiments. Once the best extraction mixture was identified, the second step of the work was performed, with the purpose of intensifying the extraction yield. Therefore, various innovative green extraction techniques, including ultrasound, using both the probe system and the ultrasonic bath, bead milling, microwave and accelerated solvent extractions were tested and compared to conventional maceration.Results, expressed in terms of total phenolic and total monomeric anthocyanin contents, showed that the best extracting solvent for ‘Violet Nori’ rice was the mixture ethanol:water (60:40 v/v), being COSMO-RS computational predictions in good correlation with the experimental results. Moreover, the most efficient techniques to extract the antioxidant compounds resulted to be both ultrasound-assisted extraction probe and bead milling, that in only 5 min got the same extractive efficiency obtained after 3 h of conventional maceration.     

Vapor–liquid–solid growth and Sb doping of Ge nanowires from a liquid Au-Sb-Ge ternary alloy

Single-crystalline Sb-doped Ge nanowires (NWs) with excellent structural properties and uniform composition have been synthesized with high yield by vapor–liquid–solid (VLS) growth by low-temperature thermal evaporation from a mixture of Ge and Sb powders. During deposition, both the Ge and the Sb dopant became incorporated in the VLS seed nanoparticle. In situ annealing experiments during transmission electron microscopy establish that a liquid ternary Au-Sb-Ge alloy constitutes the active phase of the VLS seed drop at high temperatures, which governs the growth of the one-dimensional Ge NW and its doping by Sb.     

Effect of ultrasound on the supercritical CO2 extraction of bioactive compounds from dedo de moça pepper (Capsicum baccatum L. var. pendulum)

Extracts with bioactive compounds were obtained from the red pepper variety “dedo de moça” (Capsicum baccatum L. var. pendulum) through supercritical fluid extraction with carbon dioxide assisted by ultrasound (SFE-US). The process was tested at pressures of 15, 20 and 25 MPa; temperatures of 40, 50 and 60 °C, and ultrasonic powers of 200, 400 and 600 W applied during 40, 60 and 80 min of extraction. The CO₂ mass flow rate was fixed at 1.7569 × 10⁻⁴ kg/s. Global yield, phenolic content, antioxidant capacity and capsaicinoid concentration were evaluated in the extracts. The application of ultrasound raised the global extraction yield of SFE up to 45%. The phenolic content of the extract increased with the application of higher ultrasound power and radiation time. The capsaicinoid yield was also enhanced with ultrasound up to 12%. However, the antioxidant capacity did not increase with the ultrasound application. The BET-based model and the broken and intact cell model fitted well to the kinetic SFE curves. The BET-based model with three adjustable parameters resulted in the best fits to the experimental data. Field emission scanning electron microscopy (FESEM) images showed that SFE disturbed the vegetable matrix, releasing particles from the inner region of the plant cells to their surface. When the ultrasound was applied this effect was more pronounced. On the other hand, cracks, fissures or any sign of rupture were not identified on the sample surface.     

Effects of temperature,pH, and ionic strength on the adsorption of nanoparticles at liquid–liquid interfaces

The effects of temperature, pH and sodium chloride (NaCl) concentration on the equilibrium and dynamic interfacial tension (IFT) of 4.4-nm gold nanoparticles capped with n-dodecanethiol at hydrocarbon–water interfaces was studied. The pendant drop technique was used to study the adsorption properties of these nanoparticles at the hexane–water and nonane–water interfaces. The physical size of the gold nanoparticles was determined by TEM image analysis. The interfacial properties of mixtures of these nanoparticles, having different sizes and capping agents, were then studied. The addition of NaCl was found to cause a decrease of the equilibrium and dynamic IFT greater than that which accompanies the adsorption of nanoparticles at the interface in the absence of NaCl. Although IFT values for acidic and neutral conditions were found to be similar, a noticeable decrease in the IFT was found for more basic conditions. Increasing the temperature of the system was found to cause an increase in both dynamic and equilibrium IFT values. These findings have implications for the self-assembly of functionalized gold nanoparticles at liquid–liquid interfaces.     

The Ag+ induced solution–liquid–solid growth, photoluminescence and photocatalytic activity of twinned ZnSe nanowires

Cubic ZnSe nanowires with periodically alternating twins along the wire growth direction are synthesized in the ZnCl₂–Na₂SeO₃–AgNO₃–ethylenediamine (EN)-ethylene glycol (EG)-polyvinyl–pyrrolidone (PVP) solvothermal system at 180°C for 12 h. The twinned ZnSe nanowires have diameters of 75±10 nm and lengths of >10 micrometers, and grow along 〈111〉 direction. The role of AgNO₃ in the formation of ZnSe nanowires was investigated, and an Ag⁺ induced solution–liquid–solid growth mechanism is also proposed to account for the conversion of microspheres assembled from ZnSe nanocrystallites into ZnSe nanowires. Compared with ZnSe microspheres, the as-prepared twinned ZnSe nanowires exhibit stronger band edge emissions of the wurtzite- and zinc-blende-structured ZnSe and lower deep defect related emission, and their photocatalytic ability is weaker than that of ZnSe microspheres. The results suggest that this simple, mild, one-step solution approach to fabricate ZnSe nanowires may be employed for the synthesis of other selenium compounds with one dimensional nanostructures, and provides opportunities for both fundamental research and technological applications.     

Theoretical study on the phase stability,elasticity, hardness and electronic structures of Ni–P compounds

A systematic investigation concerned with phase stability, elastic properties, hardness and relevant electronic structure of Ni–P compounds (Ni₃P, Ni₁₂P₅, Ni₂P, Ni₅P₄, NiP, NiP₂ and NiP₃) was carried out using first principles calculations. The calculated results show that the Ni–P compounds have strong hardness, ranging from 7.80–14.54 GPa. Also, the hardness values gradually increase with the P content. Electronic structure analysis shows that the strong Ni–P and part of P–P hybrid orbitals play important roles in the hardness of these compounds. The calculated elastic constants indicated that the Ni₃P, Ni₁₂P₅ and NiP₂ phases are significantly anisotropic, the NiP and Ni₂P exhibit some anisotropy, while the Ni₅P₄ and NiP₃ show a relatively isotropic character. At last, the properties of these Ni–P compounds including lattice constants, thermodynamic stability, elastic constants C_ij, bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν have been calculated.     

Total asymmetric synthesis of (–)-Phenylhistine, (–)-Aurantiamine and related compounds. Part I

A new general, short, and efficient strategy for the construction of dehydro-diketopiperazines was developed. Horner–Emmons type coupling between a phosphinyl glycine ester and a formyl heterocycle is the key coupling reaction, which proceeds in good-to-excellent yields on several sterically-hindered substrates. Moreover, racemization of the parent L-amino acids is avoided as a result of the mild basic conditions used. The selection of the NH protective group of the formyl heterocycle was crucial. N-tosylated heterocycles proved ideal for this reaction sequence. Thus, the title compounds, (–)-Phenylhistine and (–)-Aurantiamine, were prepared in high yield (four steps, 47% overall) and optical purity. Furthermore, the synthesis of unnatural derivatives including an indole analogue was successfully completed.     

Discussion notes on “Slip velocity during the flow of a liquid over a solid surface”, by E. Ruckenstein

Comments are provided for [5].     

Kinetics of copper,nickel, cobalt and iron sulfidation by a modified “pellet” method. The effect of reaction at the metal/scale interface

This paper presents the results of studies on sulfidation of copper at temperature 600–700 K, nickel at 870–890 K, cobalt at 1060–1140 K and iron at 970–1170 K in sulfur vapor at 101 kPa with the use of a modified Wagner's pellet method. It has been stated that in the case of copper and nickel the initial heating of metal samples with a corresponding sulfide greatly influences the formation of hexagonal Cu₂S or Ni_{3 ± y}S₂ which are the thermodynamically stable phases under the reaction conditions. If these sulfides are lacking the scale morphology, the sulfidation rates are different. In the case of cobalt and iron the process of sulfure dissolution does not affect the sulfidation rate. The modified pellet method permits the measurement of the sulfidation kinetics of these metals which has not been possible with the use of the classical one.     

Consequences of nanoparticle diameter and solid–liquid interfacial layer on the SWCNT/EO nanofluid flow over various shaped thin slendering needles

In this research article, we have discussed about the boundary layer flow of single walled CNT– engine oil nanofluid over three distinct nonlinearly slendering isothermal thin needles of cone, paraboloid and cylinder shapes with zero mass flux at boundary condition. We have considered the effects of diameter of SWCNT and solid–liquid interfacial layer in the thermal conductivity model of the nanofluid. We also combined single phase and double phase model to construct our model. Then after some transformations the governing equations are solved numerically and staged the effects of diameter of SWCNT and nanolayer on the characteristics of the flow through proper graphs and charts. Here, we observed that the presence of the SWCNT decreases both temperature and heat flow in the system. Also we established that cone shaped needle is the most affected by the material parameters of consideration.     

Comment on “Role of the velocity frame of reference in thermodiffusion in liquid mixtures” by M. Eslamian,C.G. Jiang and M.Z. Saghir

We analyze the material transport equations (MTE) derived by Eslamian and co-authors and address the criticism expressed regarding the approach formulated in our previous work. In doing so, we show that the MTE formulated by Eslamian and co-authors are valid only in closed stationary non-isothermal systems in combination with the restrictions on the Onsager coefficients formulated in our work which is criticized, and that for non-stationary systems the approach we took can be used.     

A response to ‘Comments on the effect of liquid layering on the thermal conductivity of nanofluids’, E. Doroodchi, T. M. Evans & B. Moghtaderi, 2009. J Nanopart Res 11(6):1501–1507

This article provides a response to a recent brief communication ‘Comments on the effect of liquid layering on the thermal conductivity of nanofluids’ by Doroodchi et al. in J Nanopart Res 11(6):1501–1507, 2009. It provides an opportunity for us to clarify the fundamental differences between the models of Yu and Choi (2003) and Leong et al. (2006) mentioned in the communication, followed by an explanation of the development of Leong et al.’s model. While we re-affirm that the model of Leong et al. (2006) was developed based on the right methodology, appropriate boundary conditions and mathematical basis and is therefore valid, there are at least three incorrect equations in Doroodchi et al.’s communication which raise serious doubts on their results calculated from the above models. Hence, the comments by Doroodchi et al. (2009) about the model of Leong et al. (2006) are not well-justified.     

Reply to a comment by S.N. Semenov and M.E. Schimpf on ‘Role of the velocity frame of reference in thermodiffusion in liquid mixtures’, Philosophical Magazine vol. 92, 705 (2012), by M. Eslamian,C.G. Jian and M.Z. Saghir.

A small angle X-ray scattering (SAXS) study of nanovoids in 99.988 and 99.995?at.% aluminium is presented. Absolute intensity calibration using a glassy carbon standard is used to extract the weak SAXS signature from nanovoids introduced by thermal quenching. SAXS analysis methods, including Guinier, Porod and Indirect Transform, are used to obtain values for the void–size, number distribution and volume fraction, as well as measures of the void-metal matrix interface structure in quenched aluminium samples. The SAXS analysis has identified a residual impurity effect on void formation and has been used to characterize trends in nanovoid size, number distribution and interface structure as a function of ageing time at elevated temperatures (artificial ageing). The work presented here, including identification of experimental tools that can be readily improved, demonstrates that SAXS studies are capable of providing precise characterization of nanovoid structure in aluminium. This level of information will be useful in developing phenomenological models of void nucleation and growth capable of linking atomic scale phenomena to macroscopic material properties.     

XRF investigation on skeletal remains from King Peter III of Aragon (1239–1285 A.D.) and Queen Blanche of Anjou (1280–1310 A.D.)

We conducted an X-Ray Fluorescence investigation on bone fragments belonging to King Peter III of Aragon and Queen Blanche of Anjou. The spectroscopic analysis was carried out in selected points of the bone fragments. Several transitional elements normally unexpected in the bone composition have been found at varying level of concentration. The presence of these elements was interpreted in relation to chemical treatments for mummification of bodies as well as to dietary habits, including tools used for cooking and for the consumption of food.     

Sum frequency generation (SFG) – surface vibrational spectroscopy studies of buried interfaces: catalytic reaction intermediates on transition metal crystal surfaces at high reactant pressures; polymer surface structures at the solid–gas and solid–liquid interfaces

SFG spectra of polyethylene and polypropylene show monolayer sensitivity and reveal temperature-dependent changes of surface structure. For polymer blends, the hydrophobic component segregates to the solid–air interface, and the hydrophilic component segregates at the solid–water interface. Changes in SFG spectra of polymer blends as a function of bulk concentration correlate with changes of contact angle. SFG is an excellent probe of surface-structure and surface-composition changes as the polymer interface is altered. Received: 20 September 1998     

Discussion on the limit cycles of the Lev Ginzburg equation by M. Bellamy and R.E. Mickens,Journal of Sound and Vibration 308 (2007) 337–342

The authors M. Bellamy and R.E. Mickens in the article “Hopf bifurcation analysis of the Lev Ginzburg equation” published in Journal of Sound and Vibration 308 (2007) 337–342, claimed that this differential equation in the plane can exhibit a limit cycle. Here we prove that the Lev Ginzburg differential equation has no limit cycles.