Effect of impurities on the Raman scattering of 6H-SiC crystals

Raman spectroscopy was applied to different-impurities-doped 6H-SiC crystals. It had been found that the first-order Raman spectra of N-, Al- and B-doped 6H-SiC were shifted to higher frequency when comparing with undoped samples. However, the first-order Raman spectra of V-doped sample was shifted to lower frequency, revealing that there existed low free carrier concentration, which might be induced by the deep energy level effect of V impurity. Meanwhile, the second-order Raman spectra are independent of polytype and impurity type

Visualization and quantification of coconut using advanced computed tomography postprocessing technology.

IntroductionComputed tomography (CT) is a non-invasive examination tool that is widely used in medicine. In this study, we explored its value in visualizing and quantifying coconut.Materials and methodsTwelve coconuts were scanned using CT for three months. Axial CT images of the coconuts were obtained using a dual-source CT scanner. In postprocessing process, various three-dimensional models were created by volume rendering (VR), and the plane sections of different angles were obtained through multiplanar reformation (MPR). The morphological parameters and the CT values of the exocarp, mesocarp, endocarp, embryo, bud, solid endosperm, liquid endosperm, and coconut apple were measured. The analysis of variances was used for temporal repeated measures and linear and non-linear regressions were used to analyze the relationship between the data.ResultsThe MPR images and VR models provide excellent visualization of the different structures of the coconut. The statistical results showed that the weight of coconut and liquid endosperm volume decreased significantly during the three months, while the CT value of coconut apple decreased slightly. We observed a complete germination of a coconut, its data showed a significant negative correlation between the CT value of the bud and the liquid endosperm volume (y = -2.6955x + 244.91; R2 = 0.9859), and a strong positive correlation between the height and CT value of the bud (y = 1.9576 ln(x) -2.1655; R2 = 0.9691).ConclusionCT technology can be used for visualization and quantitative analysis of the internal structure of the coconut, and some morphological changes and composition changes of the coconut during the germination process were observed during the three-month experiment. Therefore, CT is a potential tool for analyzing coconuts

The young fruit of Citrus aurantium L. or Citrus sinensis Osbeck as a natural health food: A deep insight into the scientific evidence of its health benefits

Fruits are consumed as foods or medicines to supply people with nutrition or treat diseases. Zhishi, the dried young fruit of Citrus aurantium L. or Citrus sinensis Osbeck, is one of the most representative health food from the fruit of the Citrus genus. It is widely used in flavorings, canned food, beverages, and medicines because of its outstanding curative effects. The bidirectional regulating effect of Zhishi on the gastrointestinal tract for treating food stagnation or diarrhea has been confirmed. Its active ingredients, including synephrine and N-methyltyramine, have been used clinically as blood pressure boosting and anti-shock drugs. Flavonoids and alkaloids of Zhishi also make it potential weight loss and beauty products due to their definite effectiveness and safety. This paper intends to review the different therapeutic applications of Zhishi and the phytochemicals associated with its medicinal values. Besides, up-to-date information on its botany and analytical methods for the quality control of the medicine is supplied. To conclude, numerous independent research on Zhishi have been conducted in the past decades, but most of them are not deep enough in elucidating its scientific evidence of its health benefits. Further studies may unveil additional pharmacological activities and is beneficial to the mankind

Lignans from Tujia Ethnomedicine Heilaohu: Chemical Characterization and Evaluation of Their Cytotoxicity and Antioxidant Activities

Heilaohu, the roots of Kadsura coccinea, has a long history of use in Tujia ethnomedicine for the treatment of rheumatoid arthritis and gastroenteric disorders, and a lot of work has been done in order to know the material basis of its pharmacological activities. The chemical investigation led to the isolation and characterization of three new (1–3) and twenty known (4–23) lignans. Three new heilaohulignans A-C (1–3) and seventeen known (4–20) lignans possessed dibenzocyclooctadiene skeletons. Similarly, one was a diarylbutane (21) and two were spirobenzofuranoid dibenzocyclooctadiene (22–23) lignans. Among the known compounds, 4–5, 7, 13–15 and 17–22 were isolated from this species for the first time. The structures were established, using IR, UV, MS and NMR data. The absolute configurations of the new compounds were determined by circular dichroism (CD) spectra. The isolated lignans were further evaluated for their cytotoxicity and antioxidant activities. Compound 3 demonstrated strong cytotoxic activity with an IC50 value of 9.92 µM, compounds 9 and 13 revealed weak cytotoxicity with IC50 values of 21.72 µM and 18.72 µM, respectively in the HepG-2 human liver cancer cell line. Compound 3 also showed weak cytotoxicity against the BGC-823 human gastric cancer cell line and the HCT-116 human colon cancer cell line with IC50 values of 16.75 µM and 16.59 µM, respectively. A chemiluminescence assay for antioxidant status of isolated compounds implied compounds 11 and 20, which showed weak activity with IC50 values of 25.56 µM and 21.20 µM, respectively

In-situ fabrication of PtSe2/MoS2 van der Waals heterojunction for self-powered and broadband photodetector

Two-dimensional transition metal dichalcogenides (2DTMDs) and their van der Waals heterojunctions (vdWHs) have garnered significant attention working as the channel material of optoelectronics. The development of new heterojunction growth schemes may also provide better performance for optoelectronic devices. In this paper, PtSe2 thin films with controllable size and thickness are directly grown on MoS2 nanosheet by sputtering-selenization two-step growth method. The photodetector with PtSe2/MoS2 heterojunction exhibits a type-I band alignment and leads to an impressive broadband spectral photoresponse (405 to 1550 nm). It can achieve responsivity as high as 5.42 A/W, a detectivity of 2.52 × 1010 Jones, and a fast response rate (92/112 μs for rise/fall time respectively). In addition, the device has excellent stability in the air atmosphere and keeps its photoresponse after even six months. The in-situ growth method provides a new scheme to construct heterojunctions of 2DTMDs and develop energy-efficient photodetectors with enhanced performance. It also supplements the practical production and application of large-scale broadband detectors