Jin-hua Piao

Comparative GC/MS Analysis of Essential Oils Extracted by 3 Methods from the Bud of Citrus aurantium L. var. amara Engl

UNLABELLED A comparative study of steam distillation extraction (SDE), reflux extraction (RE), and ultrasound-assisted extraction (USE) was conducted for the extraction of essential oils from the bud of Citrus aurantium L. var. amara Engl. Each method was evaluated in terms of qualitative and quantitative composition of the isolated essential oil by gas chromatography/mass spectrometry (GC/MS). The extract yields of essential oil were 0.16%, 2.18%, and 2.34%, respectively. A total of 82 compounds were identified by GC/MS. The main components obtained by SDE were terpinen-4-ol (20.98%), dipentene (11.67%), terpinene (9.24%), those by RE were palmitic acid (20.61%), 2-chloroethyl linoleate (14.54%), tetracosane (12.26%), and α-linolenic acid (11.24%), and those by USE were tetracosane (11.32%), heneicosane (11.06%), and palmitic acid (8.76%). Comparative analysis indicated that SDE was favorable for the extraction of monoterpene hydrocarbons, sesquiterpene hydrocarbons, alcohols, and carbonyl compounds, RE and USE had certain advantages in the extraction of aliphatic saturated hydrocarbons, organic acids, and esters. It is concluded that different extraction methods may lead to different yields of essential oils; the choice of appropriate method is very important to obtain more desired components with higher physiological activities. PRACTICAL APPLICATION C. aurantium oils from different plant parts have great economic, medicinal, and nutritional values because of their wide-spectrum biological activities. The essential oil from C. aurantium L. var amara is one of the best C. aurantium oils. The data presented in this article will help us understand the relationship between essential oils and its extraction methods and know more about the aromatic components of Citrus aurantium bud. The methods established in this study will provide useful reference information for further studies, and offer essential oil industries with helpful guidance in practice.

Effect of pyrolysis conditions on nitrogen-doped ordered mesoporous carbon electrocatalysts

Abstract Pt is the most effective and widely used electrocatalyst for the oxygen reduction reaction (ORR) in fuel cells; however, its scarcity and high cost pose a great challenge to the commercialization of the fuel cell technology. N-doped carbon materials have been regarded as one of the most promising Pt-alternative catalysts. In this work, the N-doped ordered mesoporous carbon was synthesized by the nanocasting method using SBA-15 as the template. The effect of the pyrolysis conditions (pyrolysis temperature, pyrolysis duration, and ramp rate) on this material was investigated. N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the intrinsic properties of the resultant materials. Cyclic voltammetry and rotating ring-disk electrode were used to investigate the electrochemical behavior for ORR in an alkaline medium. It was found that the resultant mesoporous carbon materials exhibit high electrical conductivity, high specific surface area, and unique pore structure. The pyrolysis temperature was the most important parameter in determining the thermodecomposition of the carbon precursor, and the microstructure, elemental composition, and chemical configuration of the resultant mesoporous carbon materials. To achieve reasonable electrocatalytic activity and selectivity, a high pyrolysis temperature above 800 °C is required for effective N doping to form active sites and for graphitization to facilitate charge transfer, whereas the pyrolysis duration and ramp rate have a much less significant effect. This indicates that both the surface composition/structure and consequent electrochemical properties are more dependent on the thermodynamics than the kinetics during the pyrolysis process. Finally, the optimal N-doped ordered mesoporous carbon catalyst showed superior electrochemical activity for ORR than the commercial Pt catalyst and is promising for fuel cell and metal–air battery applications.

Optimization of ultrasonic-assisted extraction of total saponins from Eclipta prostrasta L. using response surface methodology.

Eclipta prostrasta L. is a traditional Chinese medicine herb, which is rich in saponins and has strong antiviral and antitumor activities. An ultrasonic-assisted extraction (UAE) technique was developed for the fast extraction of saponins from E. prostrasta. The content of total saponins in E. prostrasta was determined using UV/vis spectrophotometric methods. Several influential parameters like ethanol concentration, extraction time, temperature, and liquid/solid ratio were investigated for the optimization of the extraction using single factor and Box-Behnken experimental designs. Extraction conditions were optimized for maximum yield of total saponins in E. prostrasta using response surface methodology (RSM) with 4 independent variables at 3 levels of each variable. Results showed that the optimization conditions for saponins extraction were: ethanol concentration 70%, extraction time 3 h, temperature 70 °C, and liquid/solid ratio 14:1. Corresponding saponins content was 2.096%. The mathematical model developed was found to fit well with the experimental data. Practical Application: Although there are wider applications of Eclipta prostrasta L. as a functional food or traditional medicine due to its various bioactivities, these properties are limited by its crude extracts. Total saponins are the main active ingredient of E. prostrasta. This research has optimized the extraction conditions of total saponins from E. prostrasta, which will provide useful reference information for further studies, and offer related industries with helpful guidance in practice.

Nitrogen-doped ordered mesoporous carbon: Effect of carbon precursor on oxygen reduction reactions

Aniline, pyrrole and phenanthroline, which have different nitrogen compositions, are used as carbon precursors to synthesize nitrogen-doped ordered mesoporous carbons(NOMCs) by the nanocasting method. The effect of the precursor on the resultant NOMC is extensively investigated by nitrogen adsorption-desorption measurements, scanning electron microscopy, X-ray photoelectron spectroscopy(XPS), cyclic voltammetry and rotating ring-disk electrode measurements. Salient findings are as follows. First, the precursor has a significant influence on the specific surface area and textural properties. The NOMC materials derived from pyrrole(C-PY-900: 765 m 2 /g) and phenanthroline(C-Phen-900: 746 m 2 /g) exhibit higher specific surface areas than the aniline analog(C-PA-900: 569 m 2 /g). Second, the XPS results indicate that the total nitrogen content( ca . 3.1-3.3 at%) is similar for the three carbon sources, except for a slight difference in the nitrogen configuration. Furthermore, the content of the nitrogen-activated carbon atoms is found to closely depend on the precursor, which is the highest for the phenanthroline-derived carbon. Third, the electrochemical results reveal that the electrocatalytic activity follows in the order C-PA-900 ＜ C-PY-900 ＜ C-Phen-900, confirming that the nitrogen-activated carbon atoms are the active sites for the oxygen reduction reaction(ORR). In summary, the precursor has considerable influence on the composition and textural properties of the NOMC materials, of which the ORR electrocatalytic activity can be enhanced through optimization of the NOMCs.

Chemical compositions extracted from Wikstroemia indica and their multiple activities.

Context: The rhizome of Wikstroemia indica (L.) C. A. Mey (Thymelaeaceae) is widespread in China which has been widely used in China as folk medicine for the treatment of syphilis, arthritis, whooping cough, and cancer. Due to its multiactivities, its extract has an attractive potential as a promising natural agent in the pharmaceutical industries. Objective: Aims of this study were to optimize the extraction process of the flavonoids from W. indica, and evaluate its multiple activities. Materials and methods: An orthogonal test design was employed to optimize the extraction procedure of flavonoids from W. indica. And multichromatography and spectroscopy were used to study the chemical compounds of W. indica, while several bioactivity assays were used to evaluate the antibacterial, anti-inflammatory, and antitumor activities of W. indica. Results: Optimal extraction conditions were determined: ethanol concentration was 60%; extraction time was 60 min; liquid–solid ratio was 16:1 and the power of ultrasonic instrument was 160 W. Four compounds: daphnoretin, chrysophanol, myricitrime and rutin were purified from W. indica, and chrysophanol was identified from this plant for the first time. The extract of W. indica displayed significant antimicrobial and anti-inflammatory activities. Daphnoretin showed a significant inhibition effect on CNE cells and HeLa cells lines at the concentrations ranging from 15.6 to 125 μg/mL, the tendency of antitumor effect was displayed in a concentration-dependent manner. Discussion and conclusions: Extracts of W. indica could potentially be used as a promising natural agent in the pharmaceutical industries.

Synthesis of 2D Nitrogen-Doped Mesoporous Carbon Catalyst for Oxygen Reduction Reaction

2D nitrogen-doped mesoporous carbon (NMC) is synthesized by using a mesoporous silica film as hard template, which is then investigated as a non-precious metal catalyst for the oxygen reduction reaction (ORR). The effect of the synthesis conditions on the silica template and carbon is extensively investigated. In this work, we employ dual templates—viz. graphene oxide and triblock copolymer F127—to control the textural features of a 2D silica film. The silica is then used as a template to direct the synthesis of a 2D nitrogen-doped mesoporous carbon. The resultant nitrogen-doped mesoporous carbon is characterized by transmission electron microscopy (TEM), nitrogen ad/desorption isotherms, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and rotating disk electrode measurements (RDE). The electrochemical test reveals that the obtained 2D-film carbon catalyst yields a highly electrochemically active surface area and superior electrocatalytic activity for the ORR compared to the 3D-particle. The superior activity can be firstly attributed to the difference in the specific surface area of the two catalysts. More importantly, the 2D-film morphology makes more active sites accessible to the reactive species, resulting in a much higher utilization efficiency and consequently better activity. Finally, it is noted that all the carbon catalysts exhibit a higher ORR activity than a commercial Pt catalyst, and are promising for use in fuel cells.

An ultrathin 2D semi-ordered mesoporous silica film: co-operative assembly and application

A novel ultrathin silica film with semi-ordered fingerprint-like mesopores is synthesized with the aid of the dual templates of graphene oxide (go) and tri-block copolymer P123. The formation is proposed to proceed by a co-operative assembly mechanism. As an application, the silica film is used to synthesize a 2D nitrogen-doped mesoporous carbon film, which yields superior kinetic and diffusion-limit currents than the commercial Pt/C catalyst.