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Direct laboratory shear tests, accompanied by acoustic emission (AE) monitoring, were performed to examine the influence of normal stress (ranging from 4 to 16 MPa) on the shear behavior and acoustic emission characteristics of bonded granite-concrete interfaces. The findings indicate that an increase in normal stress correlates linearly with enhancements in peak shear strength, residual strength and shear stiffness, while also facilitating a transition from ductile to brittle modes. Furthermore, elevated normal stress induced a ‘double peak stress’ phenomenon following softening, which intensified the degree of interfacial damage. AE analyses indicate that peak shear stress is responsible for generating high-energy AE signals, while the cumulative AE energy exhibits a slight increase prior to failure. Conversely, the cumulative AE count diminishes under elevated normal stresses. The b value and F-function serves as an effective indicator of crack evolution; The significant decrease in b-value at peak stress and the significant increase in F-value at peak stress are associated with brittle damage. Additionally, the proportion of shear damage signals in specimens, as determined by the joint Gaussian Mixture Model (GMM) and Support Vector Machine (SVM), was found to exceed 75% and to rise with higher normal stress levels. These findings underscore the significant influence of normal stress on the brittle-ductile transition and the degree of interfacial damage, thereby providing theoretical insights for the optimization of tunnel lining design in the context of high geostatic stresses.

Tea plants (Camellia sinensis) are commercially cultivated in >60 countries, and their fresh leaves are processed into tea, which is the most widely consumed beverage in the world. Although several chromosome-level tea plant genomes have been published, they collapsed the two haplotypes and ignored a large number of allelic variations that may underlie important biological functions in this species. Here, we present a phased chromosome-scale assembly for an elite oolong tea cultivar, “Huangdan”, that is well known for its high levels of aroma. Based on the two sets of haplotype genome data, we identified numerous genetic variations and a substantial proportion of allelic imbalance related to important traits, including aroma- and stress-related alleles. Comparative genomics revealed extensive structural variations as well as expansion of some gene families, such as terpene synthases (TPSs), that likely contribute to the high-aroma characteristics of the backbone parent, underlying the molecular basis for the biosynthesis of aroma-related chemicals in oolong tea. Our results uncovered the genetic basis of special features of this oolong tea cultivar, providing fundamental genomic resources to study evolution and domestication for the economically important tea crop.

A bioactive acidic tea polysaccharide from yellow leaves of Wuyi rock tea was successively prepared via DEAE-52 and Superdex-200 columns. Nuclear magnetic resonance (NMR) analysis showed that the main glycosidic bonds were composed of α-l-Araf-(1→, →5)-α-l-Araf-(1→, →4)-α-d-Glcp-(1→, Arap-(1→, →6)-α-d-Glcp-(1→, →2,4)-α-l-Rhap-(1→, →3,4)-α-d-Glcp-(1→, →4)-α-d-GalAp-(1→, →4)-α-d-GalAp-(1→, α-d-Galp-(1→, →6)-β-d-Galp-(1→ and →4)-β-d-Galp-(1→. The molecular weight was 3.9285 × 104 Da. The hypoglycemic effect of acidic tea polysaccharides on streptozotocin-induced type 2 diabetes mellitus rats was evaluated through histopathology and biochemistry analysis. The acidic tea polysaccharide could improve plasma and liver lipid metabolism. Moreover, 16S rRNA gene sequencing revealed that the composition of the intestinal flora changed drastically after treatment, namely, blooms of Bifidobacterium, Blautia, Dorea, and Oscillospira, and a strong reduction in Desulfovibrio and Lactobacillus. The above results illustrated that tea polysaccharides might serve as an effective ingredient to ameliorate glucose metabolism disorders and intestinal flora in hyperglycemic rats.

Black tea (Fuyun 6) samples collected from three regions, Youxi, Fu’an, and Datian, were analysed by automatic thermal desorption-gas chromatography–mass spectrometry (ATD-GC–MS) combined with the electronic nose (E-nose) technique to investigate the aroma composition differences between black teas from different regions. The response surface methodology was used to optimize the ATD conditions for extracting the aroma components from the black tea. The results revealed that the optimal conditions for aroma component accumulation from black tea samples included a sample weight of 2.8 g, an adsorption time of 39 min, an adsorption temperature of 75 °C, and a cold trap temperature of −30 °C. The ATD-GC–MS analyses identified a total of 71 aroma components in the black tea samples, of which 31 were utilized to differentiate the origins of the black teas. Additional aroma activity analyses indicated that benzyl alcohol, linalool, hexanal, octanal, and nonanal had odour activity values (OAVs) greater than 10. Additionally, the OAV of decanal exceeded 100, indicating its significant contribution to the aroma profile of Fuyun 6 black tea. The E-nose results demonstrated the ability to differentiate the black tea samples from the three different origins. This study successfully identified the specific aroma substances associated with different tea origins, providing valuable insights into the aroma characteristics of black teas from various regions.

In a humid environment, the stray current generated by subway operation will corrode the underground pipe network and the internal steel structure of the track plate, which will seriously affect the service life of the subway track plate and increase the maintenance cost later. Groundwater in subway projects mainly enters the concrete interior through capillary action and affects the concrete resistivity, and there is a lack of research on the mechanism of groundwater effect on concrete resistance. In this study, the variation of cement mortar resistivity with capillary water absorption time for cement mortar with different amounts of mineral admixtures (fly ash, ground-granulated blast furnace slag, and silica fume) was measured by the four-electrode method, and the mechanism of the influence of the electrical properties of cementitious materials under the effect of capillary water absorption was analyzed based on the mercury-pressure method (MIP) and thermogravimetric method (TG-DTG). The results show that with the increase in capillary water absorption time, the change curve of cement mortar resistivity can be divided into two stages; in the first stage, capillary water absorption leads to gel pores and transition pores quickly connecting to capillary pores and other large pores to form a water-saturated conductive pathway, resulting in a rapid decrease in resistivity, when the gel pores and excessive pores have a greater impact on resistivity. The second stage is that of capillary water absorption, to a certain extent, after the specimen’s internal water upward development rate slows down; at this time, the formation speed of the conductive pathway decreases, resulting in the rate of change in resistivity decreasing and gradually stabilizing. The incorporation of silica fume can effectively improve the resistivity of cementitious materials under the action of capillary water absorption, in which the resistivity of specimens incorporated with 15% silica fume after 36 days of capillary water absorption is 10.39 times that of the reference group, which is mainly due to its lower porosity and a higher percentage of gel pores.

Mining under the sea is a challenging task in China. Affected by blasting, tunneling, and other engineering disturbance, surrounding rock is often in a state of cyclic loading and unloading stress. In this study, in order to investigate the effect of cyclic loading and unloading on the deformation and damage characteristics of sandstone underneath the Bohai Sea, the GCTS test machine is used to conduct cyclic loading and unloading tests on sandstone. The results show that under cyclic loading and unloading compression, the stress-strain curves of sandstone form a hysteresis loop. The axial residual deformation first decreases, then increases with the increase of cycle number and unloading stress level. Both the circumferential residual strain and volumetric residual strain decrease with the increase of cycle number and unloading stress level. The axial elastic deformation increases with the increase of the cyclic number and cyclic load. The volume deformation first increases, then decreases, and the circumferential strain gradually decreases. In the process of cyclic loading and unloading, the loading elastic modulus gradually increases. Affected by damage, the unloading stress difference of sandstone initially increases with the increase of cycles. Next, the effects of cycle number and unloading stress level on the damage parameters of sandstone are analyzed. Before brittle failure of the specimen, the absolute damage parameters of axial, circumferential, and volume show an increasing trend, and the increase rates of circumferential damage parameters and volume damage parameters suddenly increase, which is also the precursor of the sandstone specimen’s instability failure.

Plants have evolved regulatory mechanisms at multiple levels to regulate gene expression in order to improve their cold adaptability. However, limited information is available regarding the stress response at the chromatin and translational levels. Here, we characterize the chromatin accessibility, transcriptional, and translational landscapes of tea plants in vivo under chilling stress for the first time. Chilling stress significantly affected both the transcription and translation levels as well as the translation efficiency of tea plants. A total of 3010 genes that underwent rapid and independent translation under chilling stress were observed, and they were significantly enriched in the photosynthesis-antenna protein and phenylpropanoid biosynthesis pathways. A set of genes that were significantly responsive to cold at the transcription and translation levels, including four (+)-neomenthol dehydrogenases (MNDs) and two (E)-nerolidol synthases (NESs) arranged in tandem on the chromosomes, were also found. We detected potential upstream open reading frames (uORFs) on 3082 genes and found that tea plants may inhibit the overall expression of genes by enhancing the translation of uORFs under chilling stress. In addition, we identified distal transposase hypersensitive sites (THSs) and proximal THSs and constructed a transcriptional regulatory network for tea plants under chilling stress. We also identified 13 high-confidence transcription factors (TFs) that may play a crucial role in cold regulation. These results provide valuable information regarding the potential transcriptional regulatory network in plants and help to clarify how plants exhibit flexible responses to chilling stress.

To explore the main aroma components and aroma differences of black tea produced from two tea cultivars, Fuyun 6 and Jinguanyin, E-nose and GC–MS were adopted. The results showed that black tea made of Jinguanyin had a floral aroma, while black tea of Fuyun 6 had a sweet aroma in the sensory review. Forty-six aroma substances in the 2 cultivars were found by GC–MS; 9 aroma substances had significant differences, including heptaldehyde, furfural, 2,2,6-trimethylcyclohexanone, 2-pentadec-2-enylfuran, cis-3-hexenyl acetate, carveol, methyl salicylate, 5-methyl-2-hexanone, and hexanal. Furthermore, the results of the E-nose showed that five out of the ten sensors were able to discriminate the two cultivars, especially, S2 (sulphide and hydrogen sulphide), S6 (biogas, hydrocarbons, and methane), S7 (combustible gases) and S10 (combustible gases and alkanes) were necessary sensors for identifying the differences between the two cultivars. The results of this study clarified the characteristics of the aroma compositions and the distinctions between black teas made of Jinguanyin and Fuyun 6. Furthermore, they provided a theoretical basis for the classification of the different cultivars and types of black tea.

Alzheimer’s disease (AD) is a common neurodegenerative disease; tea components have important neuroprotective effects. This article explores the effects and mechanisms of Qingxiang Tiguanyin (Tgy-Q), Nongxiang Tieguanyin (Tgy-N), and Chenxiang Tieguanyin (Tgy-C) extracts on APP/PS1 AD model mice. Morris water maze and new object recognition experiments show that Tieguanyin extracts can effectively enhance the cognitive ability of APP/PS1 mice. H&E staining, Nissl staining, and immunohistochemical staining show that Tieguanyin extracts make nerve cell boundaries and nucleoli become clearer, relieve nucleus pyknosis, and effectively reduce Aβ1-40 and Aβ1-42 in the hippocampus and cortex. They also restore the morphology of microglia and astrocytes. In addition, Tieguanyin extracts can balance the oxidative stress level in the brain of APP/PS1 mice by improving the antioxidant capacity. Western blot results show that Tieguanyin extracts can reduce the expression of NF-κB p65, TNF-α, IL-1β, IL-6, COX-2, and iNOS in mouse brain, which demonstrates that Tieguanyin extracts improves cognitive ability by alleviating inflammation. This article demonstrates for the first time that Tieguanyin extracts can inhibit the excessive activation of the NF-κB p65 signaling pathway and improve the antioxidant capacity in the cerebral cortex and hippocampus, to improve the cognitive ability of APP/PS1 mice. Our results shed light into the beneficial of Tieguanyin tea extracts on preventing and alleviating AD diseases.

The purpose of this study is to investigate the effects of demographic variables on tea consumption in China. A total of 12,745 samples collected from the China Health and Nutrition Survey in 2011 and a double hurdle model were used to analyze the effects of demographic variables on the extent of tea participation and consumption quantity for men and women. The results of this study indicate that the effects of demographic variables differ between genders in terms of tea participation decisions and consumption quantity decisions. For men, education, family size, region, and employment status were found to exert different effects on participation and consumption quantity decisions; for women, age, education, region, employment status, having elderly individuals in the home, and urbanization exerted different effects on their tea participation and consumption decisions. The most obvious difference between variables affecting men and women pertained to age, family size, and having elderly individuals in the home. The perspectives of each gender, coupled with the double hurdle model used in this study, offer important insights.