Characterization of the Volatile Compounds in Camellia oleifera Seed Oil from Different Geographic Origins

Volatile flavor of edible oils is an important quality index and factor affecting consumer choice. The purpose of this investigation was to characterize virgin Camellia oleifera seed oil (VCO) samples from different locations in southern China in terms of their volatile compounds to show the classification of VCO with respect to geography. Different samples from 20 producing VCO regions were collected in 2020 growing season, at almost the same maturity stage, and processed under the same conditions. Headspace solid-phase microextraction (HS-SPME) with a gas chromatography–mass spectrometer system (GC–MS) was used to analyze volatile compounds. A total of 348 volatiles were characterized, including aldehydes, ketones, alcohols, acids, esters, alkenes, alkanes, furans, phenols, and benzene; the relative contents ranged from 7.80–58.68%, 1.73–12.52%, 2.91–37.07%, 2.73–46.50%, 0.99–12.01%, 0.40–14.95%, 0.00–27.23%, 0.00–3.75%, 0.00–7.34%, and 0.00–1.55%, respectively. The VCO geographical origins with the largest number of volatile compounds was Xixiangtang of Guangxi (L17), and the least was Beireng of Hainan (L19). A total of 23 common and 98 unique volatile compounds were detected that reflected the basic and characteristic flavor of VCO, respectively. After PCA, heatmap and PLS-DA analysis, Longchuan of Guangdong (L8), Qingshanhu of Jiangxi (L16), and Panlong of Yunnan (L20) were in one group where the annual average temperatures are relatively low, where annual rainfalls are also low. Guangning of Guangdong (L6), Yunan of Guangdong (L7), Xingning of Guangdong (L9), Tianhe of Guangdong (L10), Xuwen of Guangdong (L11), and Xiuying of Hainan (L18) were in another group where the annual average temperatures are relatively high, and the altitudes are low. Hence, volatile compound distributions confirmed the differences among the VCO samples from these geographical areas, and the provenance difference evaluation can be carried out by flavor.

Investigation of Volatile Compounds in Combination with Multivariate Analysis for the Characterization of Monofloral Honeys

Lately there has been a growing demand for monofloral honeys with distinctive properties. Considering the limitations of pollen analysis, the volatile profile of honey has been proposed as a helpful supplementary tool for the confirmation of monoflorality; however, research remains regarding the volatile markers that may characterize the monofloral honey types. Therefore, in this study, we tried to expand the research by investigating the aroma profiles of five monofloral honey types (fir, pine, erica, thyme, cotton) and discriminate them through chemometric approach. A purge and trap–gas chromatograph–mass spectrometer system was used for the extraction, separation, and identification of volatile and semi-volatile compounds. Thyme honey had the richest quantitatively aroma profile, with 97 volatile compounds, whereas fir and cotton honeys had 65 and 60 volatile compounds, respectively. From a total of 124 compounds, the 38 were detected in all the studied honey types. Thyme honey was distinguished by the presence (or percentage participation) of benzeneacetaldehyde, benzealdehyde, and benzyl nitrile; erica honey of isophorone and furfural; cotton honey of 1-butanol, 2-methyl, 1-pentanol, and 4-methyl-; and honeydew honeys of α-pinene, octane, and nonanal. The discriminant analysis confirmed that the percentage participation of volatile compounds may lead to the discrimination of the studied monofloral honey types.

Dual-Gratings Imaging Spectrometer

Common dispersive-type spectroscopic instruments include prism-type and grating-type, usually using a single dispersive element. The continuous imaging band is always limited by the dispersion angle. When it is necessary to image two wavebands with an ultra-spectral resolution that are far apart, the imaging is difficult due to the large diffraction angle. To broaden the spectral coverage of the imaging spectrometer, in this paper, we propose a dual-gratings imaging spectrometer with two independently rotating gratings. In this proposed system, two very far apart wavelength bands can be imaged in the adjacent areas by adjusting the angle of the dual gratings. This greatly expands the spectral coverage of the imaging spectrometer. Currently, the only application area considered for this instrument is solar applications. In this article, we present the optical system of the dual-gratings imaging spectrometer, illustrate several advantages of the new structure, and discuss new problems caused by the dual-gratings, which are referred to as overlap between two spectra and double image offset. We deduced the calculation process of the dual grating rotation angle, the relationship between the final acquired image and the slit, the relationship between the angle change between the dual gratings and the double image offset, and the relationship between the MTF upper limit reduction and the spatial frequency. This article also summarizes the shortcomings of this structure and studies the applicable fields under these shortcomings. At last, we simulate a dual-gratings imaging spectrometer system, compare this scheme with two traditional schemes, and conclude that this instrument has certain practical significance.

Attenuation and Dispersion on Terahertz Wireless Channels in Falling Rain

Investigations on wireless channel performance in adverse weathers could be helpful and important for the future applications of terahertz communication technique in outdoor scenarios. However, in most cases only amplitude performance has been studied by using a broadband-pulsed terahertz source or an amplitude modulated data stream, not including phase degradation (temporal dispersion). This limitation may mask important aspects of channel performance with phase modulation schemes, especially for wide bandwidth signals. In this work, we report the amplitude and phase characterizations of a terahertz channel in falling rain by a time-domain spectrometer system. We also demonstrate error rate performance by a 16 quadrature amplitude modulated (16-QAM) terahertz signal at a data rate of 5 gigabits per second. We observe that, besides strong water vapor absorption, the weak water absorption line could also lead to obvious dispersion effects. Our work highlights the importance of new frequency band boundaries for minimum temporal dispersion and optimized digital communications in the terahertz frequency range.

Ni-Cu sulfide mineralization and PGM from the Samapleu mafic-ultramafic intrusion, Yacouba complex, western Ivory Coast

ABSTRACT The mafic-ultramafic Samapleu deposits of the Yacouba complex, which host nickel, copper sulfides, and platinum-group minerals, are located in the Biankouma-Silipou region, western Ivory Coast. These intrusions originate from the mantle and would have been established during the Proterozoic (2.09 Ga) around 22 km deep within the Archean granulites (3.6–2.7 Ga) which at least partially contaminated them. Platinum-group and sulfide minerals from the Samapleu deposits were studied using optical microscopy, scanning electron microscopy, the electronic microprobe, X-ray fluorescence, fire assay, and a Thermo Fisher Scientific Delta S isotope ratio mass spectrometer system. The sulfide mineralization (mainly pyrrhotite, pentlandite, chalcopyrite ± pyrite) is mainly disseminated with, in places, semi-massive to massive sulfide veins. It is especially abundant in pyroxenite horizons with net or breccia textures. The isotopic ratios of sulfur measured from the sulfides (an average of 0.1‰), the R factor (between 1500 and 10,000), and the Cu/Pd ratios indicate a mantle source. Thus, the sulfides would have formed from sulfide liquids produced by immiscibility from the silicate mantle magma under mafic-ultramafic intrusion emplacement conditions and with possible geochemical modification of the magmas by assimilation of the surrounding continental crust. The platinum-group minerals (michenerite, merenskyite, moncheite, Co-rich gersdorffite, irarsite, and hollingworthite) are mainly associated with the sulfide phases. The nature of the platinum-group minerals is indicative of the probable role of late-magmatic hydrothermal fluids during the mineralizing process.