Development and Validation of the UPLC-DAD Methodology for the Detection of Triterpenoids and Phytosterols in Fruit Samples of Vaccinium macrocarpon Aiton and Vaccinium oxycoccos L.

Cranberries are used in the production of medicinal preparations and food supplements, which highlights the importance of triterpene compounds determination in cranberry fruit raw material. The aim of our study was to develop and validate for routine testing suitable UPLC-DAD methodology for the evaluation of triterpene acids, neutral triterpenoids, phytosterols, and squalene content in cranberry samples. The developed and optimized UPLC-DAD methodology was validated according to the guidelines of the International Council for Harmonization (ICH), evaluating the following parameters: range, specificity, linearity (R² > 0.999), precision, LOD (0.27–1.86 µg/mL), LOQ (0.90–6.18 µg/mL), and recovery (80–110%). The developed and validated technique was used for the evaluation of triterpenic compounds in samples of Vaccinium macrocarpon and Vaccinium oxycoccos fruits, and their peels, pulp and seeds. The studied chromatogram profiles of Vaccinium macrocarpon and Vaccinium oxycoccos were identical but differed in the areas of the analytical peaks. Ursolic acid was the dominant compound in fruit samples of Vaccinium macrocarpon and Vaccinium oxycoccos. The highest amounts of triterpenic compounds were detected in the cranberry peels samples. The developed method for the detection of triterpene compounds can be applied in further studies for routine testing on the qualitative and quantitative composition of fruit samples of Vaccinium macrocarpon and Vaccinium oxycoccos species and cultivars.     

An Uncommon Hypervalent Fluorooxosilicophosphate

The species diversity of silicon (including traditional tetrahedral coordinated silicon and hypervalent penta‐ and hexa‐coordinate silicon) gives rise to the structural richness and diverse properties of silicates. Among these silicon species, hypervalent silicon is very rare, not to mention almost unexplored mixed‐anion hypervalent fluoroxosilicate species. In this work, we successfully obtained a mixed‐anion fluorooxosilicophosphate Na4Si2PO4F9 consisting of two uncommon hypervalent fluoroxosilicate species, namely, trans‐SiO2F4 species and SiOF₅ species. To the best of our knowledge, such hypervalent silicon species are reported for the first time in inorganic compounds. Remarkably, the coexistence of two distinct hypervalent fluoroxosilicate species in one compound is somewhat conflicted with Pauling's parsimony rule, but it indeed achieves an unlikely connection by PO₄ and our phonon dispersion calculation confirms the structure stability of Na₄Si₂PO₄F₉. Temperature‐dependent conductivity measurements show that Na₄Si₂PO₄F₉ is a promising solid ionic conductor with a high conductivity of 4.0×10^?5 S?cm^?1 at 700 K and a low active energy of about 53.1 KJ?mol^?1. This work will enrich the structure chemistry of silicates and may provide a new platform for solid ionic batteries.     

Mechanism of synthesis of anatase TiO2 pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis

In order to investigate the influence of Cl⁻/SO₄²⁻ molar ratios and hydrolysis temperature on the hydrolysis process and TiO₂ pigment, H₂TiO₃ was prepared with a low concentration of titanyl sulfuric–chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5–2.2 μm of H₂TiO₃ samples were achieved. After doping and calcination, anatase TiO₂ pigments demonstrated excellent performance: the achromic ability of tinctorial strength (TCS) and blue phase index (SCX) were 1,429 and 4.07, respectively. As hydrolysis was a significant step in the process, the structure was simplified to a periodic structure of Ti[OH](H₂O)₃Cl(SO₄) to simulate the cluster structures. Based on experimental results and density functional theory (DFT) calculation, the hydrolysis mechanism was presumed to be a process of anionic (OH⁻, Cl⁻ and SO₄²⁻) competition reaction to explain the formation of anatase-type H₂TiO₃, and the crystal growth direction of H₂TiO₃ was also confirmed to be a (OA) and b (OB).     

Dihalogenated Methylperoxy Radicals: Spectroscopic Characterization and Photodecomposition by Release of HO.

Two atmospherically relevant dihalogenated methylperoxy radicals CHX₂OO^. (X=F and Cl) have been generated through O₂-oxidation of the corresponding alkyl radicals CHX₂^. in the gas phase. The IR spectroscopic characterization of both radicals in cryogenic Ar- and N₂-matrices (15 K) is supported by ¹⁸O-labeling and ab initio calculations at the UCCSD(T)/aug-cc-pVTZ level. Upon 266 nm laser irradiation, both radicals decompose mainly by releasing hydroxyl radicals (→HO^.+X₂CO) via the intermediacy of intriguing α-hydroperoxyalkyl radicals (^.CX₂OOH), implying that the photooxidation of dihalogenated hydrocarbons might serve as important sources of HO^. radicals in the atmosphere.     

Biosynthesized Silica Nanosuspension as Thermal Fluid in Parabolic Solar Panels

In this work, the production of biologically synthesized silica nanoparticles was proposed to prepare a nanosuspension as a thermal fluid in parabolic solar panels at the laboratory level. Silica nanoparticles were produced from construction sand in two stages. Biosynthesis broth was produced by Aspergillus niger aerated fermentation in a 1 L bioreactor for 9 days. Each supernatant was contacted with 18% construction sand in a 500 L reactor with mechanical agitation, at a temperature of 25 °C, and a contact time of 30 min. Subsequently, the separation process was carried out. For day 9, a pH value of 1.71 was obtained as well as acid concentrations of 15.78 g/L for citrus and 4.16 g/L for malic. The metal extraction efficiency of Si nanoparticles was 19%. The vibration peaks in the FTIR were characteristic of the presence of silica nanoparticles in wavenumbers 1020 cm⁻¹ and 1150 cm⁻¹. Finally, a prototype solar radiation test bench for parabolic systems was built and provided with a radiation source that falls on a translucent pipe that transports the nanoparticles, which has a pump and a series of thermocouples. The heat capacity of the biotechnologically produced silica nanoparticle suspension was 0.72 ± 0.05 kJ/kgK, using material and energy balances in the flow circuit.     

Double 3-Ethyl-2,4-dimethylpyrrole Configured Fluorescent Dye with Fluorine-Boron as the Bridge

Dipyrrolydiketones BF₂ complex was synthesized and characterized by NMR, HRMS, and single crystal diffraction. In non-polar environment, this BF₂ containing dye emitted bright blue-green fluorescence. No significant spectra shift was observed both in absorption and emission spectra, which indicates the insensitivity of absorption/emission toward environment. The alkyl substituted pyrrole rings lead to its highly emission character in solid state by enhancing the distance between dye molecules. Absolute quantum yields were determined to be 0.51–0.78/0.36 in selected organic medium and solid state, respectively. The emission dynamics was investigated by fluorescence lifetime and both monoexponential and bi-exponential decay was observed.

     

Microwave-assisted and catalyst-free sulfenylation of imidazo[2,1-b]thiazoles with sulfonyl hydrazides in water

Abstract

An efficient microwave-assisted and catalyst-free sulfenylation of imidazo[2,1-b]thiazoles with sulfonyl hydrazides has been developed in water. This method is practical and environmental friendly, and can be performed within a short reaction time. The sulfenylation reaction shows high regioselectivity, and excellent functional-group compatibility, giving the desired products in moderate to good yields.     

Nanoarchitectonics in the Ionothermal Synthesis for Nucleation of Crystalline Potassium Poly (heptazine imide) Towards an Enhanced Solar-Driven H2O2 Production

Solar-driven selective oxygen reduction reaction on polymeric carbon nitride framework is one of the most promising approaches toward sustainable H₂O₂ production. Potassium poly(heptazine imide) (PHI), with regular metal sites in the framework and favorable crystalline structure, is highly active for photocatalytic selective 2e oxygen reduction to produce H₂O₂. By introducing NH₄Cl into the eutectic KCl-LiCl salt mixture, the PHI framework exhibits a remarkable performance for photocatalytic production of H₂O₂, for example, a record high H₂O₂ photo-production rate of 29.5 μmol h⁻¹ mg⁻¹. The efficient photocatalytic performance is attributed to the favorable properties of the new PHI framework, such as improved porosity, negatively shifted LUMO position, enhanced exciton dissociation and charges migration properties. A mechanistic investigation by quenching and electron spin resonance technique reveals the critical role of superoxide radicals for the formation singlet oxygen, and the singlet oxygen is one of the critical intermediates towards the formation of the H₂O₂ by proton extraction from the ethanol.     

Monolayer core-shell catalysts breaking the selectivity–activity seesaw in chemoselective hydrogenation

Metal nanoparticles are extensively used as catalysts in heterogeneous catalysis.Microscopically,the surface of metal nanoparticles contains metal atoms located at the edges,corners and terraces of the lattice planes,presenting low-and high-coordinated metal atoms[1].