Research on Foundation Deformation and Structural Stress Variation of Shaft Tower under the Influence of Frost Heave and Thaw Settlement

As the laws of structure deformation and structural stress variation under freezing construction around high-rise buildings are not clear and no engineering experience can be referred to, freezing method construction in this situation is paired with huge safety risks. In this paper, freezing construction was successfully carried out around the main shaft tower in Chensilou Coal Mine by taking the following protective measures: symmetrical drilling, local freezing and hot water circulation. The elevation of the shaft tower foundation is continuously measured during the process of drilling, frost heaving and thaw settlement (hereinafter referred to as the DHS process). Benefiting from these protective measures, the maximum inclination value (−0.406 mm/m) of the shaft tower is controlled at well below the allowable value. The observation data informed the settlement and inclination of the tower foundation during the DHS process. A numerical model of the shaft tower is further established based on the observation data to reveal the tower structure’s law of stress variation during the DHS process. In addition, the fitting equation between the tower inclination value and the structural stress is obtained, which can provide a reference for freezing construction of similar high-rise buildings

Research on Foundation Deformation and Structural Stress Variation of Shaft Tower under the Influence of Frost Heave and Thaw Settlement

As the laws of structure deformation and structural stress variation under freezing construction around high-rise buildings are not clear and no engineering experience can be referred to, freezing method construction in this situation is paired with huge safety risks. In this paper, freezing construction was successfully carried out around the main shaft tower in Chensilou Coal Mine by taking the following protective measures: symmetrical drilling, local freezing and hot water circulation. The elevation of the shaft tower foundation is continuously measured during the process of drilling, frost heaving and thaw settlement (hereinafter referred to as the DHS process). Benefiting from these protective measures, the maximum inclination value (−0.406 mm/m) of the shaft tower is controlled at well below the allowable value. The observation data informed the settlement and inclination of the tower foundation during the DHS process. A numerical model of the shaft tower is further established based on the observation data to reveal the tower structure’s law of stress variation during the DHS process. In addition, the fitting equation between the tower inclination value and the structural stress is obtained, which can provide a reference for freezing construction of similar high-rise buildings

Permanent deformation characteristics of unsaturated subgrade soils under cyclic loading

Excess permanent deformation of subgrade may cause critical rutting in pavements, and subsurface water significantly affects the accumulation of permanent deformation. This study aims to reveal the permanent deformation behaviour of unsaturated subgrade soils. Subgrade box tests were performed at varying moisture content, stress levels and loading frequency, respectively. The test results show that the permanent deformation significantly increased with moisture content. The concept of a permitted moisture content-applied dynamic load envelope was proposed. Based on curve fitting, a prediction model of permanent deformation of subgrade soils was developed, and the effects of moisture content and loading cycles were included. The validation results show that the model exhibited reasonably good performance in modelling the deformation. This study may provide an alternative way for predicting the permanent deformation of unsaturated subgrade soils

Organized Molecular Interface-Induced Noncrystallizable Polymer Ultrathin Nanosheets with Ordered Chain Alignment

The orientation and state of organization of polymer chains play significant roles in determining the final properties and functions of these materials. Unlike most semicrystalline polymers, which have an inherent driving force toward crystallization, the means to control chain packing in noncrystallizable polymers is still restricted and remains a challenge. We report herein a 2D soft template-directed fabrication for ultrathin polyacrylamide nanosheets with a thickness as low as 3.5 nm and large dimensions (>20 μm). More importantly, the polymer chains in the nanosheets produced are well aligned with a clear interchain spacing. The formation of polymer nanosheets with ordered chain alignment was performed in a special solution containing a periodic sandwich structure of lamellar bilayer membranes and water layers that are hundreds of nanometers thick. It functions as a 2D orientation template to align the monomers in an orderly manner along the in-plane direction of the bimolecular membrane via hydrogen bonding

Serum Uric Acid and the Progression of Carotid Atherosclerosis: Association in a 10-year Chinese Cohort Study of a Health Check-up Population with Normal Uric Acid Levels

Background It is considered that serum uric acid (SUA), which may induce oxidative stress and vascular endothelial dysfunction, has a potential association with atherosclerosis, but it has not been fully clarified. Objective To investigate the association of high normal SUA level with the progression of carotid atherosclerosis. Methods A retrospective cohort design was used. Participants (n=7 074) were individuals who received two or more times of health examinations in Physical Examination Center, Hebei General Hospital from 2010 to 2019. All of them had no carotid atherosclerosis with normal SUA levels〔classified into quartiles of SUA: quartile 1 (n=1 794), quartile 2 (n=1 752), quartile 3 (n=1 785) and quartile 4 (n=1 743) 〕 at the enrolment. General information, physical examination, laboratory test indicators and carotid ultrasound indicators were collected. A follow-up was conducted with them until December 2019 with the prevalence of progression of carotid atherosclerosis〔defined as carotid intima-media thickness (cIMT) greater than 1 mm or carotid atherosclerosis prevalence detected by carotid ultrasound〕 as the endpoint. Cox regression analysis was used to explore the association of SUA with carotid atherosclerosis. Results Among the participants, 1 476 (20.86%) showed progression of carotid atherosclerosis. The prevalence of carotid atherosclerosis progression in quartiles 1-4 was 17.50% (314/1 794), 21.12% (370/1 752), 21.79% (389/1 785) and 23.12% (403/1 743), respectively, demonstrating a trend of growth with the increase in SUA level (χ2trend=3.58, P<0.001). After adjusting for confounding factors, Cox regression analysis showed that the risk of carotid atherosclerosis progression in quartile 4 group was higher than that in quartile 1 group〔HR=1.46, 95%CI (1.06, 2.01), P<0.05〕. Further analysis revealed that the risk of carotid atherosclerosis progression was higher in those aged less than 60 years〔HR=1.68, 95%CI (1.15, 2.45), P<0.05〕, men〔HR=1.52, 95%CI (1.04, 2.22), P<0.05〕, non-smokers〔HR=2.12, 95%CI (1.21, 3.71), P<0.05〕, non-drinkers〔HR=1.78, 95%CI (1.13, 2.79), P<0.05〕, those without metabolic syndrome〔HR=1.51, 95%CI (1.02, 2.23), P<0.05〕, and those with BMI≤24.0 kg/m2〔HR=1.75, 95%CI (1.09, 2.81), P<0.05〕 in quartile 4 group in comparison with the corresponding conventional counterparts in quartile 1 group. Conclusion The increase of SUA level within the normal range may be associated with increased risk of carotid atherosclerosis, and the risk may be higher in those aged <60 years, men, smoking history, no drinking history, no metabolic syndrome, or having BMI≤24.0 kg/m2

The Dynamic Modulation Doping Effect of Gas Molecules on an AlGaN/GaN Heterojunction Surface

AlGaN/GaN high-electron-mobility transistors (HEMTs) are widely used in high-frequency and high-power applications owing to the high two-dimensional electron gas (2DEG) concentration. However, the microscopic origin of the 2DEG remains unclear. This hinders the development of device fabrication technologies, such as threshold voltage modulation, current collapse suppression, and 2DEG concentration enhancement technologies, as well as AlGaN/GaN sensors with very high sensitivity to polar liquids. To clarify the 2DEG microscopic origin, we studied the effects of gas molecules on AlGaN/GaN surfaces through various experiments and first-principles calculations. The results indicated that the adsorption of gas molecules on the AlGaN/GaN surface is an important phenomenon, clarifying the microscopic origin of the 2DEG. This study elucidates the properties of AlGaN/GaN heterojunctions and promotes the development of new fabrication technologies for AlGaN/GaN devices

Estrogen metabolites increase nociceptor hyperactivity in a mouse model of uterine pain

Pain emanating from the female reproductive tract is notoriously difficult to treat, and the prevalence of transient pelvic pain has been placed as high as 70%-80% in women surveyed. Although sex hormones, especially estrogen, are thought to underlie enhanced pain perception in females, the underlying molecular and cellular mechanisms are not completely understood. Here, we showed that the pain-initiating TRPA1 channel was required for pain-related behaviors in a mouse model of estrogen-induced uterine pain in ovariectomized female mice. Surprisingly, 2- and 4-hydroxylated estrogen metabolites (2- and 4-HEMs) in the estrogen hydroxylation pathway, but not estrone, estradiol, or 16-HEMs, directly increased nociceptor hyperactivity through TRPA1 and TRPV1 channels, and picomolar concentrations of 2- and 4-hydroxylation estrone (2- or 4-OHE1) could sensitize TRPA1 channel function. Moreover, both TRPA1 and TRPV1 were expressed in uterine-innervating primary nociceptors, and their expression was increased in the estrogen-induced uterine pain model. Importantly, pretreatment with 2- or 4-OHE1 recapitulated estrogen-induced uterine pain-like behaviors, and intraplantar injections of 2- and 4-OHE1 directly produced a TRPA1-dependent mechanical hypersensitivity. Our findings demonstrated that TRPA1 is critically involved in estrogen-induced uterine pain-like behaviors, which may provide a potential drug target for treating female reproductive tract pain