Probabilistic analysis is a rational approach for engineering design because it provides more insight than traditional deterministic analysis. Probabilistic evaluation on seismic stability of three ...dimensional (3D) slopes is studied in this paper. The slope safety factor is computed by combining the kinematic approach of limit analysis using a three-dimensional rotational failure mechanism with the pseudo-dynamic approach. The variability of input parameters, including six pseudo-dynamic parameters and two soil shear strength parameters, are taken into account by means of Monte-Carlo Simulations (MCS) method. The influences of pseudo-dynamic input variables on the computed failure probabilities are investigated and discussed. It is shown that the obtained failure probabilities increase with the pseudo-dynamic input variables and the pseudo-dynamic approach gives more conservative failure probability estimates compared with the pseudo-static approach.
Sustained hyperglycaemia and hyperlipidaemia incur endoplasmic reticulum stress (ER stress) and reactive oxygen species (ROS) overproduction in pancreatic β‐cells. ER stress or ROS causes c‐Jun ...N‐terminal kinase (JNK) activation, and the activated JNK triggers apoptosis in different cells. Nuclear receptor subfamily 4 group A member 1 (NR4A1) is an inducible multi‐stress response factor. The aim of this study was to explore the role of NR4A1 in counteracting JNK activation induced by ER stress or ROS and the related mechanism. qPCR, Western blotting, dual‐luciferase reporter and ChIP assays were applied to detect gene expression or regulation by NR4A1. Immunofluorescence was used to detect a specific protein expression in β‐cells. Our data showed that NR4A1 reduced the phosphorylated JNK (p‐JNK) in MIN6 cells encountering ER stress or ROS and reduced MKK4 protein in a proteasome‐dependent manner. We found that NR4A1 increased the expression of cbl‐b (an E3 ligase); knocking down cbl‐b expression increased MKK4 and p‐JNK levels under ER stress or ROS conditions. We elucidated that NR4A1 enhanced the transactivation of cbl‐b promoter by physical association. We further confirmed that cbl‐b expression in β‐cells was reduced in NR4A1‐knockout mice compared with WT mice. NR4A1 down‐regulates JNK activation by ER stress or ROS in β‐cells via enhancing cbl‐b expression.
With its high calorific value and low energy consumption, hydrogen is an important component of a future low-carbon energy system. Hydrogen production from electrolyzed water is the main source of ...obtaining hydrogen. The slow kinetics of the oxygen evolution reaction (OER) involving a four-electron reaction in the process of water electrolysis leads to the inefficiency of hydrogen production from electrolyzed water, so the development of electrocatalysts with excellent OER is of great significance. Cobalt-based catalysts are promising for electrocatalytic OER in terms of performance and cost-effectiveness, and the degree of dispersion of Co sites determines the catalytic activity. Therefore, it is of great importance to prepare highly dispersed Co-site catalysts through a convenient method. Herein, we report the facile fabrication of Co single-atom catalysts (SACs) through the use of the confined space (between the silica wall and the template) in as-prepared mesoporous silica, template-occupied KIT-6 (TOK), with abundant Si–OH. The anchoring of metal in the form of Co–O–Si was achieved by the method of grinding and calcination. CoTOK shows excellent electrocatalytic activity and cycling stability relative to the counterpart catalysts CoTFK and Co3O4/TFK, being promising for applications. This synthetic approach is easy to scale up, and 10 g of sample can be effortlessly synthesized using ball milling, which provides a facile method for the large-scale preparation of SACs.
Early pregnancy loss is a primary cause of low reproductive rates in dairy cows, posing severe economic losses to dairy farming. The accurate diagnosis of dairy cows with early pregnancy loss allows ...for oestrus synchronization, shortening day open, and increasing the overall conception rate of the herd. Several techniques are available for detecting early pregnancy loss in dairy cows, including rectal ultrasound, circulating blood progesterone, and pregnancy‐associated glycoproteins (PAGs). Yet, there is a need to improve on existing techniques and develop novel strategies to identify cows with early pregnancy loss accurately. This manuscript reviews the applications of rectal ultrasound, circulating blood progesterone concentration, and PAGs in the diagnosis of pregnancy loss in dairy cows. The manuscript also discusses the recent progress of new technologies, including colour Doppler ultrasound (CDUS), interferon tau‐induced genes (ISGs), and exosomal miRNA in diagnosing pregnancy loss in dairy cows. This study will provide an option for producers to re‐breed cows with pregnancy loss, thereby reducing the calving interval and economic costs. Meanwhile, this manuscript might also act as a reference for exploring more economical and precise diagnostic technologies for early pregnancy loss in dairy cows.
Computed tomography images are easy to misjudge because of their complexity, especially images of solitary pulmonary nodules, of which diagnosis as benign or malignant is extremely important in lung ...cancer treatment. Therefore, there is an urgent need for a more effective strategy in lung cancer diagnosis. In our study, we aimed to externally validate and revise the Mayo model, and a new model was established.
A total of 1450 patients from three centers with solitary pulmonary nodules who underwent surgery were included in the study and were divided into training, internal validation, and external validation sets (n = 849, 365, and 236, respectively). External verification and recalibration of the Mayo model and establishment of new logistic regression model were performed on the training set. Overall performance of each model was evaluated using area under receiver operating characteristic curve (AUC). Finally, the model validation was completed on the validation data set.
The AUC of the Mayo model on the training set was 0.653 (95% confidence interval CI: 0.613-0.694). After re-estimation of the coefficients of all covariates included in the original Mayo model, the revised Mayo model achieved an AUC of 0.671 (95% CI: 0.635-0.706). We then developed a new model that achieved a higher AUC of 0.891 (95% CI: 0.865-0.917). It had an AUC of 0.888 (95% CI: 0.842-0.934) on the internal validation set, which was significantly higher than that of the revised Mayo model (AUC: 0.577, 95% CI: 0.509-0.646) and the Mayo model (AUC: 0.609, 95% CI, 0.544-0.675) (P < 0.001). The AUC of the new model was 0.876 (95% CI: 0.831-0.920) on the external verification set, which was higher than the corresponding value of the Mayo model (AUC: 0.705, 95% CI: 0.639-0.772) and revised Mayo model (AUC: 0.706, 95% CI: 0.640-0.772) (P < 0.001). Then the prediction model was presented as a nomogram, which is easier to generalize.
After external verification and recalibration of the Mayo model, the results show that they are not suitable for the prediction of malignant pulmonary nodules in the Chinese population. Therefore, a new model was established by a backward stepwise process. The new model was constructed to rapidly discriminate benign from malignant pulmonary nodules, which could achieve accurate diagnosis of potential patients with lung cancer.
AIM：To investigate the expression of matrix metalloproteinases 1 and 3（MMP-1 and MMP-3） and their tissue inhibitors of metalloproteinases 1 and 3（ TIMP-1 and TIMP-3） in the conjunctiva of eyes with ...conjunctivochalasis（CCh）.METHODS：The conjunctival tissue was obtained from the CCh patients and controls,the MMPs/TIMPs expression concentration was determined by enzyme-linked immunosorbent assay（ELISA） and immunofluorescence staining.The expression levels of MMPs/TIMPs in the CCh fibroblasts were determined by analyzing its concentration in the cellular supernatant that was abstracted from the in vitro cultured CCh fibroblasts.RESULTS：MMP-1 and MMP-3 levels determined by ELISA were both significantly higher in the CCh group than that in the control group（P= 0.042,0.022,respectively）,so was the levels of TIMP-1（P= 0.010）.No significant difference in the expression of TIMP-3 in conjunctiva was found between the two groups（P= 0.298）.The expression of MMP-1 and MMP-3 were both up-regulated significantly in the CCh group（P= 0.040,0.001,respectively） on immunofluorescence staining.MMP-1 and MMP-3 expression in the fibroblasts were both significantly higher in the CCh group than that in the control group（P= 0.027,0.001,respectively）,while neither the TIMP-1 nor TIMP-3 expression was significantly different between the two groups（P= 0.421,0.237,respectively）.CONCLUSION：The overexpression of MMP-1 and MMP-3 in conjunctival tissue and fibroblasts may play an important role in the pathogenesis and development of CCh.
Solid strong base catalysts have received considerable attention in various organic reactions due to their facile separation, neglectable corrosion, and environmental friendliness. Although great ...progress has been made in the preparation of solid strong base catalysts, it is still challenging to avoid basic sites aggregation on support and active sites loss in reaction system. Here, we report a tandem redox strategy to prepare Na single atoms on graphene, producing a new kind of solid strong base catalyst (Na
1
/G). The base precursor NaNO
3
was first reduced to Na
2
O by graphene (400 °C) and successively to single atoms Na anchored on the graphene vacancies (800 °C). Owing to the atomically dispersed of basicity, the resultant catalyst presents high activity toward the transesterification of methanol and ethylene carbonate to synthesize dimethyl carbonate (turnover frequency (TOF) value: 125.7 h
−1
), which is much better than the conventional counterpart Na
2
O/G and various reported solid strong bases (TOF: 1.0–90.1 h
−1
). Furthermore, thanks to the basicity anchored on graphene, the Na
1
/G catalyst shows excellent durability during cycling. This work may provide a new direction for the development of solid strong base catalysts.
Solid base catalysts are widely used in the chemical industry owing to their advantages of environmental friendliness and easy separation. However, their application is limited by basic site ...aggregation and poor stability. In this study, we report the preparation of magnesium (Mg) single-atom catalysts with high activity and stability by a sublimation–trapping strategy. The Mg net was sublimated as Mg vapor at 620 °C, subsequently transported through argon, and finally trapped on the defects of nitrogen-doped carbon derived from metal–organic framework ZIF-8, producing Mg1/NC. Because of the atomically dispersed Mg sites, the obtained Mg1/NC exhibits high catalytic activity and stability for Knoevenagel condensation of benzaldehyde with malononitrile, which is a typical base-catalyzed reaction. The Mg1/NC catalyst achieves a high efficiency with a turnover frequency of 49.6 h–1, which is much better than that of the traditional counterpart MgO/NC (7.7 h–1). In particular, the activity of Mg1/NC shows no decrease after five catalytic cycles, while that of MgO/NC declines due to the instability of basic sites.
•K single-atom solid base catalyst (K1/SBA-15) is fabricated by a pyrolysis-free, grafting strategy.•Strong basic sites can be formed at 30 °C, which is much lower than conventional pyrolysis ...method.•Various characterizations confirm that the atomically dispersed K exists in the form of Si-O-K.•K1/SBA-15 shows better activity in transesterification compared with various solid base catalysts.
Solid base catalysts are appealing to a variety of reactions due to their benefits of easy separation, negligible corrosion, and environmental friendliness. However, their activity is compromised because high temperature is frequently required for the formation of basic sites and aggregation of basic components is easy to occur under those circumstances. Herein, K single-atom solid base catalysts were fabricated by a low temperature, pyrolysis-free, grafting strategy, resulting in the catalysts with highly dispersed basic sites and high activity in transesterification reaction. Potassium tert-butoxide (KTB) functions as the precursor and mesoporous silica SBA-15 is employed as the support, K atoms are successfully grafted onto SBA-15 (denoted as K1/SBA-15) at 30 °C. Various characterizations confirm that highly dispersed K single atoms exist in the form of K-O-Si. The amount of basic sites of K1/SBA-15 measured by titration is 1.62 mmol·g−1, verifying the basicity of the obtained catalyst. K1/SBA-15 shows excellent activity (49.1 % yield) in the transesterification reaction of ethylene carbonate (EC) and methanol to produce dimethyl carbonate (DMC), which is superior to typical alkali metal-related solid superbases. The catalyst was recovered after reaction and the yield of DMC over the recovered catalyst decreases slightly (43.4 %) due to the partial deformation of pores. Moreover, the K1/SBA-15 exhibits a turnover frequency (TOF) value of 82.5 h−1, obviously higher than various reported solid base catalysts (0.95–36.2 h−1) under semblable reaction conditions.
Background
No data exist on comparisons of efficacy, safety, and recurrence risk factors of paroxysmal and persistent atrial fibrillation (AF) ablation using robotic magnetic navigation system (MNS), ...respectively.
Methods
About 151 AF patients were prospectively enrolled and divided into paroxysmal AF group (n = 102) and persistent AF group (n = 49). Circumferential pulmonary vein antrum isolation (CPVI) was performed in all patients. Linear ablation at the left atrial roof and mitral isthmus was performed in patients with persistent AF in addition to CPVI. The procedural time, X‐ray exposure time, acute and long‐term success rates of CPVI, and procedure‐related complications were analyzed. The AF recurrence rates in the two groups were compared during 1 year, and Cox regression was used to analyze the recurrence risk factors.
Results
The acute success rates of CPVI in the two groups were 98.04% and 97.96%, respectively. There were no significant differences in the procedural time, X‐ray exposure time, and ablation time between the two groups (P > 0.05). No serious complications appeared in either group. The AF ablation success rates were 70.6% and 57.1% for the paroxysmal and persistent groups respectively at 12‐month follow‐up (P = 0.102). AF duration and coronary heart disease prior to ablation were associated with the higher AF recurrence in patients with persistent AF.
Conclusion
Ablation using MNS is effective and safe both in patients with paroxysmal and persistent AF. AF duration and coronary heart disease prior to ablation are two independent risk factors of AF recurrence in patients with persistent AF postoperatively.
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