Dynamic changes of key metabolites in Longjing green tea during processing revealed by widely targeted metabolomic profiling and sensory experiments.

In this study, widely targeted metabolomics and chemometrics were utilized to comprehensively analyse the formation of taste compounds in Longjing green tea. A total of 580 non-volatile metabolites were identified by using ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry, and alterations in three metabolic pathways were investigated. Notably, the fixation process reduced phosphatidic acid levels, resulting in the formation of lyso-phosphatidylcholine and lyso-phosphatidylethanolamine, as well as the release of esterified polyunsaturated fatty acids. Baiye No.1 had high levels of L-glutamic acid and l-glutamine, while Longjing 43 showed elevated levels of flavones. Correlation analysis and sensory verification indicated that the specific concentration of L-leucine could decrease the umami of the tea. These findings advance our understanding of Longjing green tea quality improvement and cultivar development.

Enabling Rapid and Stable Sodium Storage via a P2-Type Layered Cathode with High-Voltage Zero-Phase Transition Behavior.

Currently, a major target in the development of Na-ion batteries is the concurrent attainment of high-rate capacity and long cycling stability. Herein, an advanced Na-ion battery with high-rate capability and long cycle stability based on Li/Ti co-doped P2-type Na0.67 Mn0.67 Ni0.33 O2 , a host material with high-voltage zero-phase transition behavior and fast Na+ migration/conductivity during dynamic de-embedding process, is constructed. Experimental results and theoretical calculations reveal that the two-element doping strategy promotes a mutually reinforcing effect, which greatly facilitates the transfer capability of Na+ . The cation Ti4+ doping is a dominant high voltage, significantly elevating the operation voltage to 4.4 V. Meanwhile, doping Li+ shows the function in charge transfer, improving the rate performance and prolonging cycling lifespan. Consequently, the designed P2-Na0.75 Mn0.54 Ni0.27 Li0.14 Ti0.05 O2 cathode material exhibits discharge capacities of 129, 104, and 85 mAh g- 1 under high voltage of 4.4 V at 1, 10, and 20 C, respectively. More importantly, the full-cell delivers a high initial capacity of 198 mAh g-1 at 0.1 C (17.3 mA g-1 ) and a capacity retention of 73% at 5 C (865 mA g-1 ) after 1000 cycles, which is seldom witnessed in previous reports, emphasizing their potential applications in advanced energy storage.

Ultraflexible Temperature-Strain Dual-Sensor Based on Chalcogenide Glass-Polymer Film for Human-Machine Interaction.

Skin-like thermoelectric (TE) films with temperature- and strain-sensing functions are highly desirable for human-machine interaction systems and wearable devices. However, current TE films still face challenges in achieving high flexibility and excellent sensing performance simultaneously. Herein, for the first time, a facile roll-to-roll strategy is proposed to fabricate an ultraflexible chalcogenide glass-polytetrafluoroethylene composite film with superior temperature- and strain-sensing performance. The unique reticular network of the composite film endows it with efficient Seebeck effect and flexibility, leading to a high Seebeck coefficient (731 µV/K), rapid temperature response (≈0.7 s), and excellent strain sensitivity (gauge factor = 836). Based on this high-performance composite film, an intelligent robotic hand for action feedback and temperature alarm is fabricated, demonstrating its great potential in human-machine interaction. Such TE film fabrication strategy not only brings new inspiration for wearable inorganic TE devices, but also sets the stage for a wide implementation of multifunctional human-machine interaction systems.

High Seebeck Coefficient Inorganic Ge15Ga10Te75 Core/Polymer Cladding Fibers for Respiration and Body Temperature Monitoring.

Wearable thermal sensors based on thermoelectric (TE) materials with high sensitivity and temperature resolution are extensively used in medical diagnosis, human-machine interfaces, and advanced artificial intelligence. However, their development is greatly limited by the lack of materials with both a high Seebeck coefficient and superior anticrystallization ability. Here, a new inorganic amorphous TE material, Ge15Ga10Te75, with a high Seebeck coefficient of 1109 µV/K is reported. Owing to the large difference between the glass-transition temperature and initial crystallization temperature, Ge15Ga10Te75 strongly inhibits crystallization during fiber fabrication by thermally codrawing a precast rod comprising a Ge15Ga10Te75 core and PP polymer cladding. The temperature difference can be effectively transduced into electrical signals to achieve TE fiber thermal sensing with an accurate temperature resolution of 0.03 K and a fast response time of 4 s. It is important to note that after the 1.5 and 5.5 K temperatures changed repeatedly, the TE properties of the fiber demonstrated high stability. Based on the Seebeck effect and superior flexibility of the fibers, they can be integrated into a mask and wearable fabric for human respiration and body temperature monitoring. The superior thermal sensing performance of the TE fibers together with their natural flexibility and scalable fabrication endow them with promising applications in health-monitoring and intelligent medical systems.

Trajectories of cognitive reactivity and its predictive value on postpartum depression in Chinese women: a latent class growth modeling analysis.

Many women are experiencing postpartum depression (PPD) after giving birth. How to recognize and intervene in high-risk PPD women early and effectively remains unknown. Our objective is to describe the latent trajectory groups of cognitive reactivity (CR) in perinatal women, and their relationship to demographic and disease-related factors, as well as investigate the associations with PPD. Data from 321 perinatal women who were evaluated in urban tertiary hospitals in China at three-time points: 32-35 weeks of pregnancy, 1 week postpartum, and 6 weeks postpartum. Latent class growth modeling was used to identify the trajectory patterns of CR and logistic regression was used to explore the association between demographic and disease-related factors, CR trajectories, and depression. Three trajectory groups were identified: the continuing deterioration group (17.2%), the postpartum deterioration group (22.1%), and the consistent resilient group (60.7%). Participants with a bachelor's degree or higher and with gestational diabetes diagnosis were more likely to be in the continuing deterioration group. Those who were from only-child families were more likely to be in the postpartum deterioration group. Women in the continuing deterioration group and postpartum deterioration group were more likely to experience PPD. Targeted interventions should be developed based on trajectory group of CR.

Microwave-Assisted Synthesis of Highly Active Single-Atom Fe/N/C Catalysts for High-Performance Aqueous and Flexible All-Solid-State Zn-Air Batteries.

The development of low-cost single-atom electrocatalysts for oxygen reduction reaction (ORR) is highly desired but remains a grand challenge. Superior to the conventional techniques, a microwave-assisted strategy is reported for rapid production of high-quality Fe/N/C single-atom catalysts (SACs) with profoundly enhanced reaction rate and remarkably reduced energy consumption. The as-synthesized catalysts exhibit an excellent ORR performance with a positive half-wave potential up to 0.90 V, a high turnover frequency of 0.76 s-1 , as well as a satisfied stability with a lost half-wave potential of just 27 mV over 9000 cycles (much better than that of Pt/C with 107 mV lost) and good methanol resistance. The open-circuit voltages of as-constructed aqueous and flexible all-solid-state Zn-air batteries (ZABs) are 1.56 and 1.52 V, respectively, higher than those of 20% Pt/C-based ones (i.e., 1.43 and 1.38 V, respectively). Impressively, they afford a peak power density of 235 mW cm-2 , which exceeds that of Pt/C (i.e., 186 mW cm-2 ), and is comparable to the best ones of Fe/N/C-based ZABs ever reported.

Superflexible Inorganic Ag2 Te0.6 S0.4 Fiber with High Thermoelectric Performance.

Fiber-based inorganic thermoelectric (TE) devices, owing to the small size, light-weight, flexibility, and high TE performance, are promising for applications in flexible thermoelectrics. Unfortunately, current inorganic TE fibers are strictly constrained by limited mechanical freedom because of the undesirable tensile strain, typically limited to a value of 1.5%, posing a strong obstacle for further application in large-scale wearable systems. Here, a superflexible Ag2 Te0.6 S0.4 inorganic TE fiber is demonstrated that provides a record tensile strain of 21.2%, such that it enables various complex deformations. Importantly, the TE performance of the fiber shows high stability after ≈1000 cycles of bending and releasing processes with a small bending radius of 5 mm. This allows for the integration of the inorganic TE fiber into 3D wearable fabric, yielding a normalized power density of 0.4 µW m-1 K-2 under the temperature difference of 20 K, which is approaching the high-performance Bi2 Te3 -based inorganic TE fabric and is nearly two orders of magnitude higher than the organic TE fabrics. These results highlight that the inorganic TE fiber with both superior shape-conformable ability and high TE performance may find potential applications in wearable electronics.

Supporting routine cognitive reactivity assessment during the perinatal period: psychometric testing of the Chinese version of the Leiden Index of Depression Sensitivity.

BACKGROUND: It is critical to find optimal forms to identify perinatal depression (PND) and its vulnerable factors and make them more applicable to depression screening. This study aims to evaluate the reliability and validity of the Chinese version of the Leiden Index of Depression Sensitivity (LEIDS-RR-CV) among perinatal women in China and determine the cut-off values for screening for high-risk depression. METHODS: Women in their third trimester of pregnancy and six weeks postpartum completed the LEIDS-RR-CV and a diagnostic reference standard online. We assessed the LEIDS-RR-CV using classical test theory (CTT) and item response theory (IRT). We also assessed the test performance for cut-off scores using receiver operator characteristic analysis to further screen for high-risk depression at each time point. RESULTS: In total, 396 (third trimester) and 321 (six weeks postpartum) women participated. Cronbach's alpha, two-week test-retest reliability, and marginal reliability for the scale were all greater than 0.8. It showed a five-factor model; the cut-off values were 58 (third trimester) and 60 (six weeks postpartum). The areas under the curve were acceptable (≥ 0.7), and the LEIDS-RR-CV was positively correlated with the total Edinburgh Postnatal Depression Scale (EPDS) score (r = 0.52 and 0.56, p = 0.00), indicating its predictive validity. An IRT analysis further confirmed its discriminative validity. CONCLUSIONS: The LEIDS-RR-CV was found to be reliable, valid, and can be used to quantify cognitive reactivity among perinatal Chinese women and for screening for high-risk depression during this period.

Exogenous stimulation-induced biosynthesis of volatile compounds: Aroma formation of oolong tea at postharvest stage.

Volatile organic compounds (VOCs) are produced by plants responding to biotic and abiotic stresses. According to their biosynthetic sources, induced VOCs are divided into three major classes: terpenoids, phenylpropanoid/benzenoid, and fatty acid derivatives. These compounds with specific aroma characteristics importantly contribute to the aroma quality of oolong tea. Shaking and rocking is the crucial procedure for the aroma formation of oolong tea by exerting mechanical damage to fresh tea leaves. Abundant studies have been carried out to investigate the formation mechanisms of VOCs during oolong tea processing in recent years. This review systematically introduces the biosynthesis of VOCs in plants, and the volatile changes due to biotic and abiotic stresses are summarized and expatiated, using oolong tea as an example.

Comparative Analysis of Volatile Compounds in Tieguanyin with Different Types Based on HS-SPME-GC-MS.

Tieguanyin (TGY) is one kind of oolong tea that is widely appreciated for its aroma and taste. To study the difference of volatile compounds among different types of TGY and other oolong teas, solid-phase microextraction−gas chromatography−mass spectrometry and chemometrics analysis were conducted in this experiment. Based on variable importance in projection > 1 and aroma character impact > 1, the contents of heptanal (1.60−2.79 µg/L), (E,E)-2,4-heptadienal (34.15−70.68 µg/L), (E)-2-octenal (1.57−2.94 µg/L), indole (48.44−122.21 µg/L), and (E)-nerolidol (32.64−96.63 µg/L) in TGY were higher than in other varieties. With the increase in tea fermentation, the total content of volatile compounds decreased slightly, mainly losing floral compounds. Heavily fermented tea contained a higher content of monoterpenoids, whereas low-fermentation tea contained higher contents of sesquiterpenes and indole, which could well distinguish the degree of TGY fermentation. Besides, the volatiles analysis of different grades of TGY showed that the special-grade tea contained more aroma compounds, mainly alcohols (28%). (E,E)-2,4-Heptadienal, (E)-2-octenal, benzeneacetaldehyde, and (E)-nerolidol were the key volatile compounds to distinguish different grades of TGY. The results obtained in this study could help enrich the theoretical basis of aroma substances in TGY.

Effects of baking treatment on the sensory quality and physicochemical properties of green tea with different processing methods.

Seven batches of raw tea leaves, processed by different methods (steaming, pan-frying) and from two different harvesting seasons (spring, autumn), were used to investigate the effect of baking treatment on changes in the composition and content of nonvolatile and volatile compounds. The results showed that baking had a greater impact on sensory and flavor quality, which chemically modified some of taste and aroma components. The aroma concentrations of steamed teas (4,168-10,706 µg/L) were significantly higher than those of pan-fried teas (959-2,608 µg/L), and the aroma concentrations of baked green teas (2,608-10,706 µg/L) were significantly higher than those of unbaked teas (959-4,213 µg/L). Based on VIP > 1 and ACI > 1, (E, E)-3,5-octadien-2-one, hexanal, ß-ionone, 5-methylfurfural, ß-cyclocitral, and linalool were identified as the main aroma compounds. Chemical changes resulting from Maillard reaction were greater during baking of steamed, than pan-fried green tea. These results help improve the quality of green tea with baking.

A targeted and nontargeted metabolomics study on the oral processing of epicatechins from green tea.

Oral processing (OP), referring to the whole process of food digestion in human mouth, has a major influence on food flavor perception. This study focused on the compositional changes of the four green tea epicatechins (viz., EC, EGC, ECG, EGCG) during OP, based on targeted and nontargeted metabolomics. It was found that the four epicatechins were all extensively lost through transformation undergoing OP, among which EC was the most stable one, whereas EGCG the least. EGCG was further revealed to be susceptible to human oral cavity in the simulated OP in vitro. It could be converted physically by precipitating with mucin in saliva, and chemically through hydrolysis and dimerization, mediated mainly by the neutral pH condition. The OP of epicatechins also caused salivary composition changes possibly involving health benefits of green tea. These findings could raise awareness of the interactions between epicatechins, or any other food materials, with human mouth.

Sensory and chemical characteristics of Tieguanyin oolong tea after roasting.

Roasting, a critical process for oolong tea, has been applied to Tieguanyin tea to improve flavor attributes. To investigate the effects of the roasting on the flavor of Tieguanyin, the global metabolomics analysis on the non-volatile and volatile components were proceeded. The weakening of bitterness and astringency, caused by roasting, may be attributed to the decreasing of flavonoids glycosides and procyanidins, whereas the enhancing of sweet aftertaste to the increasing of gallic acid. Besides, l-theanine flavan-3-ols adducts (N-ehtyl-2-pyrrolidinone substituted flavan-3-ols) increased dramatically at 130 °C compared with 105 °C, with the reduction of l-theanine and flavan-3-ols. Meanwhile, high temperature hampered the volatiles' diversity and intensity, resulting from the lowering of floral volatiles, i.e., ß-ionone, jasmine, and nerolidol, yet the nitrogen-containing heterocyclic compounds increased, e.g., pyrroles and pyrazines. The results can help to comprehensively understand the influences of roasting technology on the flavor and chemistry of oolong tea.

Zijuan tea- based kombucha: Physicochemical, sensorial, and antioxidant profile.

Zijuan tea is a representative anthocyanin-rich tea cultivar in China. In this study, Zijuan tea was used to produce a novel kombucha beverage (ZTK). The physicochemical, sensory properties, and antioxidant activity of ZTK were compared with that of black tea kombucha (BTK) and green tea kombucha (GTK). Results indicated that after fermentation, the color of ZTK changed from yellowish-brown to salmon-pink, because its anthocyanins (4.5 mg/L) appeared red in acidic conditions. Meanwhile no significant changes of color were observed in BTK and GTK. The dynamic changes of pH, biomass, and concentrations of sugars, amino acids, and main organic acids were similar in three kombucha beverages, except catechins showing different trends. Moreover, ZTK showed the highest overall acceptability score, antioxidant activity, and concentration of volatiles among the three kombucha beverages. Therefore, Zijuan tea is suitable for the preparation of kombucha beverage with attractive color and health benefits.

Effect of chemical composition of black tea infusion on the color of milky tea.

Milky tea is popular in many countries and its color is an important sensory property. The effects of black tea infusion on the color of milky tea prepared with non-dairy creamer were investigated. The results showed that the redder black tea infusion produced milky tea with more redness, and the color of milky tea was a pleasant pink when the a* value (redness indicator) was in the range of 6.0-7.0. Correlation analysis revealed that the respective theaflavins (TFs), thearubigins (TRs), thearubigins (TBs), (-)-epigallocatechin-3-gallate (EGCG) and chlorogenic acid contents significantly correlated with the a* values of milky tea. A series of complementary experiments were performed to elucidate that TFs and EGCG contributed to the redness of milky tea. The color formation was mainly associated with the binding of phenols to the proteins in the non-dairy creamer. These results contribute to understand the mechanism of color formation in milky tea.

Effect of baking on the flavor stability of green tea beverages.

Flavor stability is important for the quality of tea beverages. Baking is a typical processing technology to improve the flavor of tea leaves. In present study, seven raw tea materials, including steamed spring and autumn tea leaves, pan-fired spring tea leaves, and their corresponding baked tea leaves, were used to investigate the effect of baking on flavor stability of green tea beverages. The results showed that tea beverages prepared with baked tea had better flavor stability. The baking process obviously changed the concentrations of some important flavor substances, especially the aromatic pyrrole substances from 0 (unbaked) to 338.13 µg/L (baked) in tea beverages. Heat treatment had little influence on the flavor of tea beverages prepared from baked tea, but caused great changes in non-volatile and volatile components in those prepared from unbaked leaves. These results could help guide the processing of tea beverages which would improve their flavor quality stability.

Chemical composition, sensory properties and bioactivities of Castanopsis lamontii buds and mature leaves.

Castanopsis lamontii is used as functional herbal tea in southwest China. Usually, only buds rather than mature leaves are applied. To figure out whether mature leaves were suitable for producing herbal tea, chemical composition, sensory properties and bioactivities of Castanopsis lamontii bud infusion (CLB) and mature leaf infusion (CLM) were investigated. According to the results, CLB and CLM had similar non-volatile composition, but in different proportion. Meanwhile, CLB contained more types of volatiles than CLM, leading to distinguishable volatile profiles between them. Sensory assessment showed that CLB had sweet aftertaste and floral aroma. CLM tasted astringent and smelled grassy. Bioactivity evaluation indicated that CLB exhibited higher activities in scavenging free radicals and suppressing lipopolysaccharide-induced inflammation. Taken together, CLB had better overall acceptability in sensory quality and higher bioactivity, implying that Castanopsis lamontii buds were more suitable for producing herbal tea.

LiFePO4-Graphene Composites as High-Performance Cathodes for Lithium-Ion Batteries: The Impact of Size and Morphology of Graphene.

In this work, we investigated three types of graphene (i.e., home-made G, G V4, and G V20) with different size and morphology, as additives to a lithium iron phosphate (LFP) cathode for the lithium-ion battery. Both the LFP and the two types of graphene (G V4 and G V20) were sourced from industrial, large-volume manufacturers, enabling cathode production at low cost. The use of wrinkled and/or large pieces of a graphene matrix shows promising electrochemical performance when used as an additive to the LFP, which indicates that the features of large and curved graphene pieces enable construction of a more effective conducting network to realize the full potential of the active materials. Specifically, compared to pristine LFP, the LFP/G, LFP/G V20, and LFP/G V4 show up to a 9.2%, 6.9%, and 4.6% increase, respectively, in a capacity at 1 C. Furthermore, the LFP combined with graphene exhibits a better rate performance than tested with two different charge/discharge modes. Moreover, from the economic and electrochemical performance view point, we also demonstrated that 1% of graphene content is optimized no matter the capacity calculated, based on the LFP/graphene composite or pure LFP.

Screening and Determination of Potential Risk Substances Based on Liquid Chromatography-High-Resolution Mass Spectrometry.

Nontargeted analysis is a useful strategy for the discovery of unknown risk compounds. However, how to rapidly screen and determine risk substances is still a big challenge. In this study based on high-performance liquid chromatography (HPLC)-high resolution mass spectrometry (HRMS), a strategy for the rapid screening and determination of risk substances was established. First, the distribution characteristic of every feature from HRMS in all samples was studied by the mean deviation ratio (MDR) calculation. Features with MDR more than 20 were thought to be the first match of obvious suspected substances. Second, the structure characteristics of specific classes of substances which were summarized from our in-house risk substance (IHRS) database with about 500 different additives and drugs were used to rapidly screen the unknown suspected substances with specific structure classes. To further identify the above suspected risk substances, IHRS retrieval was carried out. For the unknown features not included in IHRS database, the exclusion of endogenous substances and multiple network databases searching were first performed, and the remaining substances had to be identified with comprehensive methods. To test the usefulness of the established screening and identification method, 42 meat samples were analyzed and 6 risk substances were discovered and identified, with the usefulness of the method confirmed.

Synthesis of magnetic mesoporous metal-organic framework-5 for the effective enrichment of malachite green and crystal violet in fish samples.

A novel, magnetic and mesoporous Fe3O4@PEI-MOF-5 material was synthesized for the effective enrichment of malachite green (MG) and crystal violet (CV) in fish samples. The Fe3O4@PEI-MOF-5 material was prepared by a facile two-step solvothermal approach in which Fe3O4@PEI and MOF-5 were connected through chemical bonds. Characterization of the newly synthesized Fe3O4@PEI-MOF-5 material was performed by Fourier transform infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. This new material was determined to have high magnetization and chemical stability, a large surface area and a distinctive morphology. An effective enrichment and detection method for MG and CV was subsequently developed by combining the Fe3O4@PEI-MOF-5 material with ultra-high-performance liquid chromatography-tandem mass spectrometry. The linearity ranges of this approach for MG and CV were 1-500ng/mL and 0.25-500ng/mL, respectively, with correlation coefficients (R2) of 0.999. The limits of detection (LODs) of the method for MG and CV were 0.30ng/mL and 0.08ng/mL, respectively, indicating that the Fe3O4@PEI-MOF-5 material had good adsorption properties for MG and CV. Fe3O4@PEI-MOF-5 can be expected to also provide efficient enrichment of MG and CV in other complex matrices.