Composition of Peel Essential Oils from Eight Citrus Species

The peel essential oils from eight citrus species growing in Taiwan were analysed to determine the detailed composition of each oil.     

天然超疏水生物表面研究的新进展

文章简要地论述了表面浸润性的基本理论，介绍了几种天然超疏水生物表面最新的研究进展，包括荷叶、蝉翼、水稻叶以及水黾腿，特别介绍了作者的研究小组利用从壁虎脚高黏附力获得的灵感仿生制备出一种对水滴具有高黏附的超疏水阵列聚苯乙烯纳米管材料，最后对超疏水材料的研究趋势作了展望。     

分光光度法测定桔皮中橙皮苷含量

用分光光度法测定桔皮中橙皮苷的含量 ,显色体系最大吸收波长在 4 2 2 nm处 ,表观摩尔吸光系数ε=4 .2 1× 10 4 L· mol-1· cm-1,橙皮苷含量在 0— 60μg/ m L范围内符合比耳定律。该法简便可靠 ,可获得满意的分析结果     

Microencapsulation Preservation of the Stability and Efficacy of Citrus Grandis Oil-Based Repellent Formulation against Aedes aegypti during Storage

Essential oils have been widely used as an active ingredient in mosquito repellent products. However, essential oils are highly unstable and prone to degradation when exposed to the environment during storage. Microencapsulation techniques help to maintain the stability of molecules in essential oils that are sensitive to environmental stress, and therefore improve shelf life. In this study, the physical stability and efficacy of a repellent formulation consisting of encapsulated Citrus grandis essential oil (CGEO) were evaluated under different storage conditions over a 12-month period by comparing the formulation with a non-encapsulated formulation. The formulations were both stored under two different storage conditions, i.e., 25 ± 2 °C/60% ± 5% relative humidity (RH) and 40 ± 2 °C/75% RH ± 5%, for 12 months. Droplet size, zeta potential, and pH value were measured after 1, 6, and 12 months of storage to determine their stability. For the study of efficacy, each formulation was tested against Aedes aegypti under laboratory conditions. We found that the microencapsulated formulation’s physical characteristics showed insignificant changes as compared with the non-encapsulated formulation during storage. The microencapsulated formulation demonstrated better repellent effects, sustaining high protection (>80%) for 4 more hours of exposure after 12 months of storage as compared with the non-encapsulated formulation that demonstrated high protection for only an hour post application. Microencapsulation helped to preserve the stability of the formulation, which resulted in high protection being maintained for over 12 months of storage.     

Facile Biogenic Synthesis and Characterization of Seven Metal-Based Nanoparticles Conjugated with Phytochemical Bioactives Using Fragaria ananassa Leaf Extract

In this investigation, for the first time, we used Fragaria ananassa (strawberry) leaf extract as a source of natural reducing, capping or stabilizing agents to develop an eco-friendly, cost-effective and safe process for the biosynthesis of metal-based nanoparticles including silver, copper, iron, zinc and magnesium oxide. Calcinated and non-calcinated zinc oxide nanoparticles also synthesized during a method different from our previous study. To confirm the successful formation of nanoparticles, different characterization techniques applied. UV-Vis spectroscopy, X-ray Diffraction (XRD) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), Photon Cross-Correlation Spectroscopy (PCCS) and Fourier Transformed Infrared Spectroscopy (FT-IR) were used to study the unique structure and properties of biosynthesized nanoparticles. The results show the successful formation of metal-based particles in the range of nanometer, confirmed by different characterization techniques. Finally, the presented approach has been demonstrated to be effective in the biosynthesis of metal and metal oxide nanoparticles.     

Compositional Changes in Grapes and Leaves as a Consequence of Smoke Exposure of Vineyards from Multiple Bushfires across a Ripening Season

The negative effects of smoke exposure of grapes in vineyards that are close to harvest are well documented. Volatile phenols in smoke from forest and grass fires can contaminate berries and, upon uptake, are readily converted into a range of glycosylated grape metabolites. These phenolic glycosides and corresponding volatile phenols are extracted into the must and carried through the winemaking process, leading to wines with overtly smoky aromas and flavours. As a result, smoke exposure of grapes can cause significant quality defects in wine, and may render grapes and wine unfit for sale, with substantial negative economic impacts. Until now, however, very little has been known about the impact on grape composition of smoke exposure very early in the season, when grapes are small, hard and green, as occurred with many fires in the 2019–20 Australian grapegrowing season. This research summarises the compositional consequences of cumulative bushfire smoke exposure of grapes and leaves, it establishes detailed profiles of volatile phenols and phenolic glycosides in samples from six commercial Chardonnay and Shiraz blocks throughout berry ripening and examines the observed effects in the context of vineyard location and timing of smoke exposure. In addition, we demonstrate the potential of some phenolic glycosides in leaves to serve as additional biomarkers for smoke exposure of vineyards.     

Magnetically separable tea leaf mediated nickel oxide nanoparticles for excellent photocatalytic activity

Synthesis of nanoparticles having low chemical toxicity has been interest of researchers for decades. Utilization of plant phytochemicals as reducing agent is now a globally recognized alternative technique for environmental friendly and low-cost production of nanoparticles. This work reports a facile green synthesis protocol of Nickel Oxide nanoparticles (NiO NPs) using fresh tea leaf extract. The synthesized nanoparticles have been characterized through various analytical techniques like Powder XRD (P-XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The XRD results reveal the formation of crystalline nickel oxide nanoparticles. FTIR spectrum displays the existence of different polyphenolic groups over NiO NPs surface. TEM and SEM images indicate the formation of slightly agglomerated spherical nanoparticles with particle size 3–5 ​nm. The nanoparticles were used towards the photocatalytic degradation of both cationic, anionic dyes and their mixtures under optimum conditions in the presence of UV light irradiation. More than 95% degradation was observed for all the dye solutions with 30 ​mg ​L^-1 catalytic dose. Moreover, the degradation efficiency of the nanoparticle was studied by altering various parameters like pH, initial dye concentration and amount of catalytic dose. Pseudo first order kinetic model was employed in all the reactions. A detailed mechanism and kinetics of the all the reactions were studied. Interestingly, the catalyst showed excellent recyclability up-to 4th cycles with very low catalytic activity loss.     

Effects of ascorbic acid on the physiochemical,rheological, and antioxidant properties of citrus essential oil-based emulsion stabilized by pectin

The present study was conducted to enhance the peel of Citrus sinensis (sweet orange) by using their essential oils (EOs) as a potential source of natural bioactive molecules. EOs were obtained by hydrodistillation and their chemical profile was determined through GC-MS analysis. O/W EO emulsions were prepared using pectin as biopolymer emulsifier at different proportions, including different amounts of ascorbic acid (0, 0.5, and 1% w/w). The effect of pectin and ascorbic acid concentrations on the stability and rheological behavior of emulsions was investigated. It was found that adding ascorbic acid to the appropriate concentration of pectin enhances the interfacial membranes surrounding the oil droplets and decreases the droplet sizes. As a result both the viscoelastic modules and the resulting viscosity of emulsions increase leading to an improvement of their stability. Antioxidant activity of orange EO emulsion in combination with ascorbic acid was found significantly higher than that without ascorbic acid, and higher than that of individual components. Overall, this study would be helpful in developing more effectives systems with promising physical and antioxidant characteristics for the preservation of foods.     

Cinnamomum tamala leaf extract-mediated green synthesis of Ag nanoparticles and their use in pyranopyrazles synthesis

A novel, biochemical, and eco-friendly method has been developed for the synthesis of Ag nanopar-ticles using an aqueous leaf extract of readily accessibleCinnamomum tamala as reducing and stabi-lizing agents. These Ag nanoparticles were used to catalyze the synthesis of pyranopyrazoles. The green nature and ease of recovery and reusability of the catalyst, together with high yields of prod-ucts, make this protocol attractive and useful.