Effect of blanching, acid type, and temperature on the extraction of anthocyanin from Tibouchina semidecandra flower

Extraction is the most common way to obtain anthocyanins from their natural matrices. During the extraction, the anthocyanin may degrade due to the heat and acidic solvent. The objectives of this research were to determine the best acidic aqueous solution and temperature to extract anthocyanin from Tibouchina semidecandra flower and to decide if the blanching process has a significant effect on the extracted anthocyanin. The T. semidecandra petals were separated into two groups: steam blanched for 6 mins and without blanching. Both were dried for 24 hrs at 45°C and powdered. The extract was prepared by macerating the powdered petal into pH 3 aqueous solutions made of three different acids (citric, malic, and hydrochloric acid, respectively) in a water bath shaker at various temperatures (30, 45, 60, and 75°C) for an hour. The extracts were then filtered, centrifuged, and analysed for their colour intensity, browning index, monomeric anthocyanin, polymeric anthocyanin, and total phenolic content. The best method to obtain the highest colour intensity, monomeric anthocyanin, total phenolic content, and lowest browning index was using steam-blanched dried petal, citric or malic acid as solvent and extraction temperature at 60°C. The total monomeric anthocyanin and phenolic content of the extract was 3.63±0.35 mg/g dried petal and 74.47±11.47 mg/g dried petal, respectively.

Principles governing control of aggregation and dispersion of aqueous graphene oxide

Controlling the structure of graphene oxide (GO) phases and their smaller analogues, graphene (oxide) quantum dots (GOQDs), is vitally important for any of their widespread intended applications: highly ordered arrangements of nanoparticles for thin-film or membrane applications of GO, dispersed nanoparticles for composite materials and three-dimensional porous arrangements for hydrogels. In aqueous environments, it is not only the chemical composition of the GO flakes that determines their morphologies; external factors such as pH and the coexisting cations also influence the structures formed. By using accurate models of GO that capture the heterogeneity of surface oxidation and very large-scale coarse-grained molecular dynamics that can simulate the behaviour of GO at realistic sizes of GOQDs, the driving forces that lead to the various morphologies in aqueous solution are resolved. We find the morphologies are determined by a complex interplay between electrostatic, $${\pi }$$ π –$${\pi }$$ π and hydrogen bonding interactions. Assembled morphologies can be controlled by changing the degree of oxidation and the pH. In acidic aqueous solution, the GO flakes vary from fully aggregated over graphitic domains to partial aggregation via hydrogen bonding between hydroxylated domains, leading to the formation of planar extended flakes at high oxidation ratios and stacks at low oxidation ratios. At high pH, where the edge carboxylic acid groups are deprotonated, electrostatic repulsion leads to more dispersion, but a variety of aggregation behaviour is surprisingly still observed: over graphitic regions, via hydrogen bonding and “face-edge” interactions. Calcium ions cause additional aggregation, with a greater number of “face-face” and “edge-edge” aggregation mechanisms, leading to irregular aggregated structures. “Face-face” aggregation mechanisms are enhanced by the GO flakes possessing distinct domains of hydroxylated and graphitic regions, with $${\pi }$$ π –$${\pi }$$ π and hydrogen bonding interactions prevalent between these regions on aggregated flakes respectively. These findings furnish explanations for the aggregation characteristics of GO and GOQDs, and provide computational methods to design directed synthesis routes for self-assembled and associated applications.

Enhancing Precursor Quality of Cu-In-S Ternary Thin Films by Applying More Appropriate Deposition Procedure

Copper indium sulphur (CIS) thin films were electrochemically grown from an acidic aqueous solution including 10 mM CuCl2, 10 mM InCl3, 20 mM Na2S2O3 and 200 mM LiCl. Deposition potential is determined by means of cyclic voltammetry analysis. The precursor CIS thin films are produced at -1.10 V for 600 s, -0.90 V for 300 s and a mixed potential of -0.25 V for 150 s and -1.10 V for 150 s. It is reported that surface morphology and film stoichiometry vary remarkably with the deposition parameters. SEM images show a variation in the grain shape, homogeneity and agglomeration due to the different Cu/In ratio. The produced films have XRD peaks belonging to both CIS2 crystalline phase and S element. The produced CIS material at -1.1 V has a band gap of 1.66 eV. The CIS thin film produced at -0.9 V has three different band gaps such as 1.76, 2.59 and 2.85 eV. The CIS material produced by two steps has also three different band gaps between 1.59 and 2.74 eV. The CIS films are p-type, and resistivity and mobility data are in the range 6.56-8.61 Ωcm and 8.68-22.2 cm2/Vs, respectively. It is found that the acceptor concentration of CIS thin films varies between 2.48x1017 and 1.06x1018 cm-3. In summary, this study reports a procedure to produce high-quality precursor CIS thin films, highlighting a promising material to be used in heterostructure photovoltaic devices as a p-type absorber layer.

Simple Synthesis of Ru Decahedral Hollow Nanocages with Face-Centered Cubic Structure

Metallic nanocrystals with specific morphologies are of great interest to various applications, in particular for nanocages with well-defined and controllable surface due to high surface-to-volume ratio with high utilization efficiency of atoms. In the present work, Ru decahedral nanocages were synthesized via a combination of seed-mediated growth and chemical etching approach over Pd decahedra seeds. To be specific, the Pd decahedra were synthesized via a standard procedure, on which the Ru out layers were grown by seed-mediated growth with a few nanometers. Subsequently, Ru decahedral nanocages were formed with selective chemical etching of Pd cores in acidic aqueous solution. The present work suggests an effective strategy towards synthesis of hollow nanocages.

Globular pattern formation of hierarchical ceria nanoarchitecture

Dissipative structures often appear as an unstable counterpart of ordered structures owing to fluctuations that do not form a homogeneous phase. Even a multiphase mixture may simultaneously undergo one chemical reaction near equilibrium and another one that is far from equilibrium. Here, we observed in real time crystal seed formation and simultaneous nanocrystal aggregation proceeding from CeIV complexes to CeO2 nanoparticles in an acidic aqueous solution, and investigated the resultant hierarchical nanoarchitecture. The formed particles exhibited two very different size ranges. The hierarchically assembled structures in solutions were CeO2 colloids, viz. primary core clusters (1–3 nm) of crystalline ceria and secondary clusters (20–30 nm) assembled through surface ions. Such self-assembly is widespread in multi-component complex fluids, paradoxically moderating hierarchical reactions. Stability and instability are not only critical but also complementary for co-optimisation around the nearby free energy landscape prior to bifurcation.

Synthesis and Characterization of 1,10-phenanthroline-mono-N-oxides

N-oxides of N-heteroaromatic compounds find widespread applications in various fields of chemistry. Although the strictly planar aromatic structure of 1,10-phenanthroline (phen) is expected to induce unique features of the corresponding N-oxides, so far the potential of these compounds has not been explored. In fact, appropriate procedure has not been reported for synthesizing these derivatives of phen. Now, we provide a straightforward method for the synthesis of a series of mono-N-oxides of 1,10-phenanthrolines. The parent compounds were oxidized by a green oxidant, peroxomonosulfate ion in acidic aqueous solution. The products were obtained in high quality and at good to excellent yields. A systematic study reveals a clear-cut correlation between the basicity of the compounds and the electronic effects of the substituents on the aromatic ring. The UV spectra of these compounds were predicted by DFT calculations at the TD-DFT/TPSSh/ def2-TZVP level of theory.

Investigation of Microstructure and Corrosion Resistance of Ti-Al-V Titanium Alloys Obtained by Spark Plasma Sintering

The research results of the microstructure and corrosion resistance of Ti and Ti-Al-V Russian industrial titanium alloys obtained by spark plasma sintering (SPS) are described. Investigations of the microstructure, phase composition, hardness, tensile strength, electrochemical corrosion resistance and hot salt corrosion of Ti-Al-V titanium alloy specimens were carried out. It was shown that the alloy specimens have a uniform highly dense microstructure and high hardness values. The studied alloys also have high resistance to electrochemical corrosion during tests in acidic aqueous solution causing the intergranular corrosion as well as high resistance to the hot salt corrosion. The assumption that the high hardness of the alloys as well as the differences in the corrosion resistance of the central and lateral parts of the specimens are due to the diffusion of carbon from the graphite mold into the specimen surface was suggested.