Characteristic Aroma and Molecular Sensory Analysis of Black Teas from Different Regions by Gas Chromatography-Mass Spectrometry and Gas Chromatography-Olfactometry

In order to investigate the differences in the characteristic aroma of black teas from different regions, the volatile aroma compounds of Keemun black tea, Yichang black tea, Dianhong black tea and Yingde black tea were identified by solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) and were evaluated by gas chromatography-olfactory (GC-O). Odor activity value (OAV) calculation and correlation analysis between sensory aroma profile and key aroma-active compounds were performed to analyze the sensory attributes and chemical basis of the characteristic aroma of black tea. The results showed that the four black teas differed in the sensory attributes of seven aroma notes such as floral, sweet and herbal notes. Additionally, 24 differential key aroma compounds were identified (P 1). Geraniol contributed most to black tea aroma with the highest OAV in Keemun black tea (16 581.33), followed by Yichang black tea (7 463.65), Dianhong black tea (2 832.13) and Yingde black tea (467.96). Partial least squares (PLS) regression analysis and Pearson correlation analysis showed that β-ionone, geraniol and indole were responsible for the floral and sweet aroma of Keemun black tea, (Z)-3-hexenol and α-terpineol contributed to the fruity and woody aroma of Dianhong black tea, and 2-heptanol and (Z)-linalooloxide were responsible for the herbal aroma of Yingde black tea. In conclusion, this study has preliminarily clarified the characteristic aroma profiles of black tea from the four regions and their material basis at the molecular level

A Novel Synergistic Flame Retardant of Hexaphenoxycyclotriphosphazene for Epoxy Resin

Hexaphenoxycyclotriphosphazene (HPCP) is a common flame retardant for epoxy resin (EP). To improve the thermostability and fire safety of HPCP-containing EP, we combined UiO66-NH2 (a kind of metal-organic frame, MOF) with halloysite nanotubes (HNTs) by hydrothermal reaction to create a novel synergistic flame retardant (H-U) of HPCP for EP. For the EP containing HPCP and H-U, the initial decomposition temperature (T5%) and the temperature of maximum decomposition rate (Tmax) increased by 11 and 17 °C under nitrogen atmosphere compared with those of the EP containing only HPCP. Meanwhile, the EP containing HPCP and H-U exhibited better tensile and flexural properties due to the addition of rigid nanoparticles. Notably, the EP containing HPCP and H-U reached a V-0 rating in UL-94 test and a limited oxygen index (LOI) of 35.2%. However, with the introduction of H-U, the flame retardant performances of EP composites were weakened in the cone calorimeter test, which was probably due to the decreased height of intumescent residual char

Gait impairment-related axonal degeneration in Parkinson’s disease by neurite orientation dispersion and density imaging

Abstract Microstructural alterations in the brain networks of Parkinson’s disease (PD) patients are correlated with gait impairments. Evaluate microstructural alterations in the white matter (WM) fiber bundle tracts using neurite orientation dispersion and density imaging (NODDI) technique in PD versus healthy controls (HC). In this study, 24 PD patients and 29 HC were recruited. NODDI and high-resolution 3D structural images were acquired for each participant. The NODDI indicators, including the intracellular neurite density index (NDI), orientation dispersion index (ODI), and isotropic volume fraction (ISO), were compared between the two groups. Diffusion-weighted (DW) images were preprocessed using MRtrix 3.0 software and the orientation distribution function to trace the main nerve fiber tracts in PD patients. Quantitative gait and clinical assessment scales were used to compare the medication “ON” and “OFF” states of PD patients. The NDI, ODI, and ISO values of the WM fiber bundles were significantly higher in PD patients compared to HC. Fiber bundles, including the anterior thalamic radiation, corticospinal tract, superior longitudinal fasciculus, forceps major, cingulum, and inferior longitudinal fasciculus, were found to be significantly affected in PD. The NDI changes of PD patients were well correlated with stride lengths in the “ON” state; ODI changes were correlated with the stride time in the “ON” and “OFF” states and ISO changes were correlated with the stride time and cadence in the “ON” state. In conclusion, combination of NODDI technique and gait parameters can help detect gait impairment in PD patients early and accurately

Realizing a Brain-Like Transistor Memory with Triple Data-Storage Modes by One Single Smart Molecular Dopant in the Dielectric Layer

Human brain simultaneously gains sensory memory, short-term memory, and long-term memory, which allows information from the outside world to be sensed in the form of chemical and physical stimuli and enables highly efficient information storage, exchange, and processing. Such intelligent memory behavior guarantees human beings to not only solve the most complicated tasks but also rapidly respond to external environments. Developing brain-like memory with versatile data-storage modes plays an increasingly important role in modern information technologies. However, traditional memory devices generally only show one single mode of memory and suffer from poor tunability. To this end, here we develop a brain-like transistor memory with triple operation modes (i.e., sensory, short-term, and long-term memory) by doping the dielectric layer with multistimuli responsive donor–acceptor Stenhouse adducts. When been written with humidity, the transistor behaves like a “sensory memory” as the data fade immediately upon humidity removal. When been written with light, the transistor exhibits a volatile memory and could be erased by heating, analogous to the “short-term memory.” Further, when the transistor is programmed by heat or electrical field, a long-term memory is created. This work opens a new door to design intelligent memories for advanced applications