Dynamic information about the cutting force of each cutter, such as peak and frequency of normal force, is essential to address the deformation and vibration of the cutterhead during tunnel ...construction using tunnel boring machines (TBM). Existing theoretical/empirical models of cutting forces and models of cutterhead deformation and vibration often use static forces for simplified analysis. It will have an impact on cutterhead design and performance analysis. In this study, a dynamic cutting force model is established based on the cavity expansion model and discretization method. This model calculates the period of the cutting force from cutter size, operation parameters and rock strength. Then, it is applied to the equation of motion of the cutterhead as the external load. The natural frequency, mode shape, deformation, and forced vibration of the cutterhead are analyzed. Finally, the cutterhead vibration response was calculated under typical geological conditions and operating parameters. The results show that increased installation radius of cutter, rotational speed and penetration of cutterhead increase the volume of rock extruded by the cutter per unit of time. The core boundary velocity and the frequency of cutting forces are also increased. Furthermore, the dynamic response of the cutterhead is significantly correlated with the geological conditions and operation parameters. Using greater advance rate and rotational speeds on stronger rocks results in most severe vibration of the cutterhead. These results demonstrate that the model provides theoretical support for cutterhead vibration analysis.
Highlights
The series of tests performed on the full-scale rotary cutting machine with a synchronous monitoring system for the force of the cutter and the vibration of the cutterhead reveals the significant influence of the rock and operating parameters on cutting force and cutterhead vibration.
The proposed novel dynamic cutting force model with rock and operation parameters is proved useful in analyze dynamic information of cutting force.
The presented detailed mechanistic analysis of cutterhead vibration applying dynamic forces for TBM tunneling identifies the key parameters controlling system vibration and permits transferring theoretical results to in situ applications.
This study investigated the optimization of ultrasonic-assisted aqueous two-phase synchronous extraction of carbohydrates and polyphenols present in artichoke bud, evaluated their antioxidant ...activities in vitro, and analyzed the composition of carbohydrates and polyphenols by high-performance liquid chromatography (HPLC). The powder mass, ultrasonic time, ammonium sulfate concentration, and alcohol-water ratio were considered the influencing factors based on the single-factor experiment results, and a dual-response surface model was designed to optimize the synchronous extraction process to extract carbohydrates and polyphenols. The antioxidant activity was evaluated by measuring the scavenging capacity of ABTS
· and DPPH· and the reducing capacity of Fe
. The optimal process conditions in this study were as follows: the powder mass of 1.4 g, ammonium sulfate concentration of 0.34 g/mL, alcohol-water ratio of 0.4, and ultrasonic time of 43 min. The polyphenol content in artichoke bud was 5.32 ± 0.13 mg/g, and the polysaccharide content was 74.78 ± 0.11 mg/g. An experiment on in vitro antioxidant activity showed that both carbohydrates and polyphenols had strong antioxidant activities, and the antioxidant activity of polyphenols was stronger than that of carbohydrates. The HPLC analysis revealed that the carbohydrates in artichoke bud were mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, and arabinose, and the molar ratio was 10.77:25.22:2.37:15.74:125.39:48.62:34.70. The polyphenols comprised chlorogenic acid, 4-dicaffeoylquinic acid, caffeic acid, 1,3-dicaffeoylqunic acid, isochlorogenic acid B, isochlorogenic acid A, cynarin, and isochlorogenic acid C, and the contents were 0.503, 0.029, 0.022, 0.017, 0.008, 0.162, 1.621, 0.030 mg/g, respectively. This study also showed that the carbohydrates and polyphenols in artichoke bud could be important natural antioxidants, and the composition analysis of HPLC provided directions for their future research. Carbohydrates and polyphenols in artichoke buds can be separated and enriched using the optimized process technology, and it is an effective means of extracting ingredients from plants.
We study the wave functions and purely leptonic decays of b-flavored mesons (pseudoscalars, vector mesons, and higher excited states that are well established in experiment) in the relativistic ...potential model based on our previous works. The wave functions are obtained by solving the wave equation including the spin-spin and spin-orbit corrections in the effective potential. The decay constants of B, B*, and some of their excited states that have been found in experiment are calculated with these wave functions. Then the branching fractions of the purely leptonic decay modes of these bottom mesons are studied. Our results are well in agreement with experimental data for decay modes that have been measured in experiments. We also provide predictions for some yet unmeasured channels, which are useful for experimental testing in the future.
Bacterial vaginosis (BV) is one of the most common infections among women of reproductive age and accounts for 15-50% of infections globally. The role played by folate in the pathogenesis and ...progression of BV is poorly understood. The aim of this study was to investigate the association between serum folate, red blood cell (RBC) folate, and BV in American women.
1,954 participants from the 2001-2004 National Health and Nutrition Examination Survey (NHANES) program were included in this study. Multiple logistic regression was used to analyze the association between serum folate, RBC folate, and BV, and covariates including race, age, education level, and body mass index were used to construct adjusted models. Stratified analysis was used to explore the stability of the above associations in different populations.
In the present cross-sectional study, we found that serum folate and RBC folate were inversely associated with the risk of BV. In the fully adjusted model, the risk of BV was reduced by 35% (OR=0.65, 95% CI: 0.51~0.83, p=0.0007) in the highest serum folate group and 32% (OR=0.68, 95% CI: 0.53~0.87, p=0.0023) in the highest RBC folate group compared to the lowest group.
The results of this study indicated that serum folate and RBC folate were inversely associated with the risk of BV folate supplementation may play an important role in the prevention and management of BV.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Estimation of cutting forces has been used in the design and performance prediction of tunnel boring machines. The relationship between rock strength and integrity, cutting force, torque, and ...vibration response was investigated by the synchronous monitoring system of the full-scale rotary cutting machine. The results showed that the penetration and rotation speed of the cutterhead were important operating parameters affecting the cutting force. Moreover, the penetration also greatly influenced the cutting force. The size, position, and frequency of the cutting force significantly correlated with the vibration of the cutterhead. The root mean square (RMS) of the acceleration component in the tunnel direction was the key feature. Soft–hard mixed stratum could be identified by the RMS of vibration. Based on these results, an empirical formula for predicting cutting force was constructed. The Colorado School of Mines model underestimated the normal forces acting on soft rocks, and the gradient boosting decision tree has the best effect in predicting the cutting force.
Various mycotoxins widely co-exist in agro-products, and their combined effects cause toxicity and potential carcinogenicity to humans and animals. In this work, we developed an economical and ...sensitive quantum dots (QDs)/QD microbead (QDs/QB)-based multiplex immunochromatographic assay (mICA) for the rapid detection of fumonisin B1 (FB1), zearalenone (ZEN), and ochratoxin A (OTA) without the building-up process of mycotoxin conjugates. QDs and QBs were selected as fluorescent reporters and conjugated with antimycotoxin monoclonal antibodies for improving sensitivity. Furthermore, phage-displayed FB1, ZEN, and OTA mimotope peptide-based soluble and monovalent fusions to maltose-binding protein (MBP) were applied onto the test line of the mICA as the mimetic coating antigen. Under the optimized conditions, the visual detection limits (vLODs) of peptide–MBP-based mICA could be obtained as 0.25 ng/mL for FB1, 3.0 ng/mL for ZEN, and 0.5 ng/mL for OTA within 10 min. The results for spiked real sample detection indicate good accuracy, reproducibility, and practicability. In addition, the proposed mICA was comparable with ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) in terms of reliability in detecting FB1, ZEN, and OTA using natural samples. From the point of promoting commercial production, these time-saving and low-cost peptide–MBP antigens applied in ICA might provide promising potential for promoting productivity and decreasing the cost of production.
Zr-doped HfO2(HZO)-based germanium (Ge) p-channel ferroelectric FET (p-FeFET) memory devices with microwave annealing (MWA) followed by rapid thermal annealing (RTA) are employed as the platform to ...investigate the impact of <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray radiation on the device performance. With a radiation dose of 1 Mrad, the memory window (MW) degrades from 2.5 V to 2.0 V accompanied by the significantly increased off-state current. The deleterious radiation effect is ascribed to the susceptible quality of the interface between the gate dielectric and source/drain region due to exacerbated charge trapping for the Ge substrate. These trapped charges also screen the polarization charges after applying a voltage pulse and lead to increased read-after-write latency. Nevertheless, compared with the irradiated HfO2-based FeFET memories in the literature, the Ge p-FeFETs in this work demonstrate competitive anti-radiation capability in terms of a large MW of 1.5 V even after <inline-formula> <tex-math notation="LaTeX">10^{{5}} </tex-math></inline-formula> cycles by bipolar stress (±4 V/<inline-formula> <tex-math notation="LaTeX">1~\mu \text{s} </tex-math></inline-formula>) and desirable retention up to 10 years under low voltage operation.
In this work we study the decay constants of B and Bs mesons based on the wave function obtained in the relativistic potential model. Our results are in good agreement with experimental data which ...enables us to apply this method to the investigation of B-meson distribution amplitudes. A very compact form of the distribution amplitude is obtained. We also investigate the one-loop QCD corrections to the pure leptonic decays of B mesons. We find that, after subtracting the infrared divergence in the one-loop corrections using the factorization method, the QCD one-loop corrections to the hard amplitude of leptonic decay will be zero.
•New methods for the controlling harmful cyanobacterial blooms are urgent.•A new algicidal compound from Salvia miltiorrhiza Bung was isolated and identified.•Neo-przewaquinone A destroyed the M. ...aeruginosa cell structure.•Neo-przewaquinone A induced oxidative damage of M. aeruginosa.•Neo-przewaquinone A reduced expression of the photosynthesis-related genes.
The present study was to isolate and identify a potent algicidal compound from extract of Salvia miltiorrhiza and study the potential inhibition mechanism on Microcystis aeruginosa. Column chromatography and bioassay-guided fractionation methods were carried out to yield neo-przewaquinone A, which was identified by spectral analysis. The EC50 of neo-przewaquinone A on M. aeruginosa were 4.68mgL−1. In addition, neo-przewaquinone A showed relatively higher security on Chlorella pyrenoidosa and Scenedesmus obliquus, with the EC50 values of 14.78 and 10.37mgL−1, respectively. For the potential inhibition mechanisms, neo-przewaquinone A caused M. aeruginosa cells morphologic damage or lysis, increased malondialdehyde content and decreased the soluble protein content, total antioxidant and superoxide dismutase activity, and significantly inhibited three photosynthesis-related genes (psaB, psbD, and rbcL). The results demonstrated the algicidal effect of neo-przewaquinone A on M. aeruginosa and provided the possible inhibition mechanisms.
Recent research suggests that periodontitis can increase the risk of chronic obstructive pulmonary disease (COPD). In this study, we performed two-sample Mendelian randomization (MR) and investigated ...the causal effect of periodontitis (PD) on the genetic prediction of COPD. The study aimed to estimate how exposures affected outcomes.
Published data from the Gene-Lifestyle Interaction in the Dental Endpoints (GLIDE) Consortium's genome-wide association studies (GWAS) for periodontitis (17,353 cases and 28,210 controls) and COPD (16,488 cases and 169,688 controls) from European ancestry were utilized. This study employed a two-sample MR analysis approach and applied several complementary methods, including weighted median, inverse variance weighted (IVW), and MR-Egger regression. Multivariable Mendelian randomization (MVMR) analysis was further conducted to mitigate the influence of smoking on COPD.
We chose five single-nucleotide polymorphisms (SNPs) as instrumental variables for periodontitis. A strong genetically predicted causal link between periodontitis and COPD, that is, periodontitis as an independent risk factor for COPD was detected. PD (OR = 1.102951, 95% CI: 1.005-1.211, p = 0.039) MR-Egger regression and weighted median analysis results were coincident with those of the IVW method. According to the sensitivity analysis, horizontal pleiotropy's effect on causal estimations seemed unlikely. However, reverse MR analysis revealed no significant genetic causal association between COPD and periodontitis. IVW (OR = 1.048 > 1, 95%CI: 0.973-1.128, p = 0.2082) MR Egger (OR = 0.826, 95%CI:0.658-1.037, p = 0.1104) and weighted median (OR = 1.043, 95%CI: 0.941-1.156, p = 0.4239). The results of multivariable Mendelian randomization (MVMR) analysis, after adjusting for the confounding effect of smoking, suggest a potential causal relationship between periodontitis and COPD (P = 0.035).
In this study, periodontitis was found to be independent of COPD and a significant risk factor, providing new insights into periodontitis-mediated mechanisms underlying COPD development.
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