Rockburst Intensity Grade Prediction Model Based on Batch Gradient Descent and Multi-Scale Residual Deep Neural Network

Rockburst is a phenomenon in which free surfaces are formed during excavation,which subsequently causes the sudden release of energy in the construction of mines and tunnels.Light rockburst only peels off rock slices without ejection,while severe rockburst causes casualties and property loss.The frequency and degree of rockburst damage increases with the excavation depth.Moreover,rockburst is the leading engineering geological hazard in the excavation process,and thus the prediction of its intensity grade is of great significance to the development of geotechnical engineering.Therefore,the prediction of rockburst intensity grade is one problem that needs to be solved urgently.By comprehensively considering the occurrence mechanism of rockburst,this paper selects the stress index(σθ/σc),brittleness index(σ_(c)/σ_(t)),and rock elastic energy index(Wet)as the rockburst evaluation indexes through the Spearman coefficient method.This overcomes the low accuracy problem of a single evaluation index prediction method.Following this,the BGD-MSR-DNN rockburst intensity grade prediction model based on batch gradient descent and a multi-scale residual deep neural network is proposed.The batch gradient descent(BGD)module is used to replace the gradient descent algorithm,which effectively improves the efficiency of the network and reduces the model training time.Moreover,the multi-scale residual(MSR)module solves the problem of network degradation when there are too many hidden layers of the deep neural network(DNN),thus improving the model prediction accuracy.The experimental results reveal the BGDMSR-DNN model accuracy to reach 97.1%,outperforming other comparable models.Finally,actual projects such as Qinling Tunnel and Daxiangling Tunnel,reached an accuracy of 100%.The model can be applied in mines and tunnel engineering to realize the accurate and rapid prediction of rockburst intensity grade.

Co-transport of dissolved organic matter and heavy metals in soils induced by excessive phosphorus applications

To evaluate the effects of long-term applications of phosphorus fertilizers on mobility of dissolved organic matter （DOM） and heavy metals in agricultural soils, a sandy soil and a loamy soil were spiked with ammonium phosphate at application rates of 0, 25, 50, 100, 250, and 500 mg P per kilogram of soil. A series of 15-cm long soil columns were constructed by packing incubated soils of varying concentrations of P. The soil columns were consecutively leached by simulated rainfalls for six cycles. The contents of water extractable organic carbon in both sandy and loamy soils increased significantly with increasing rates of P applications. Relatively high rates of P applications could induce a marked increase in DOM concentrations in the leachates, the effects were larger with the sandy soil rather than with the loamy soil. Applications of P changed the partitioning of trace metals in the soil solids and the soil solutions. The increased P application rates also seemed to elevate the leaching of Cu, Cd, and Zn from soils. The concentrations of Cu, Cd, and Zn in the leachates were positively correlated with DOM, probably due to the formation of metal-DOM complexes. In contrast, Pb concentrations in the leachates were negatively correlated with DOM, and decreased with increasing rates of P applications. The boosted leaching of DOM induced by high rates of P applications was probably due to the added phosphate ions competing for adsorption sites in the soil solids with the indigenous DOM.

Strategy and technique for surgical treatment of Ebstein’s anomaly

Background:Ebstein’s anomaly(EA)is a rare and complex congenital heart anomaly,and the effect of surgical treatment is not ideal.This study aims to introduce our experience in management strategies,surgical techniques,and operative indications for patients with Ebstein’s anomaly.Methods:A retrospective study of 258 operations was performed in 253 patients by the same cardiac surgeon in The First Hospital of Tsinghua University between March 2004 and January 2020.32 patients had previously received cardiac surgery in other hospitals.The clinical data including diagnosis,operative indications,techniques,pathological changes,and survival rates were collected and analyzed.Results:Anatomical correction was performed in 203(78.7%)operations,1½ventricle repair in 38(14.7%)operations,tricuspid valve repair only in four operations(1.6%),tricuspid valve replacement in ten(3.9%),total cavopulmonary connection(TCPC)in two(0.8%),and Glenn operation in one operation(0.4%).Reoperation was performed in five patients(2.0%)during hospitalization.Among them,tricuspid valve replacement was performed in one patient,1½ventricle repair in two patients,and tricuspid valve annulus reinforcement in two patients.Five patients died with an early mortality rate of 2.0%.Complete atrioventricular conduction block was complicated in one patient(0.4%).A total of 244 patients was followed up(four in the 253 patients lost)with a duration of 3.0-168.0(87.6±38.4)months.Cardiac function of 244 patients improved significantly with mean New York Heart Association(NYHA)functional class recovery from 3.5 to 1.1.The mean grade of tricuspid valve regurgitation improved from 3.6 to 1.5.Three late deaths(1.2%)occurred.The survival rates at five and ten years after surgery were 98.6%and 98.2%,respectively.Reoperation was performed in five patients(2.0%)during the follow-up period.Conclusion:Based on our management strategies and operative principles and techniques,anatomical correction of EA is capable of achieving excellent long-term results,and low rates of TCPC,1½ventricle repair and valvular replacement.

Overexpressed SIRT6 ameliorates doxorubicin-induced cardiotoxicity and potentiates the therapeutic efficacy through metabolic remodeling

Since the utilization of anthracyclines in cancer therapy, severe cardiotoxicity has become a major obstacle. The major challenge in treating cancer patients with anthracyclines is minimizing cardiotoxicity without compromising antitumor efficacy. Herein, histone deacetylase SIRT6 expression was reduced in plasma of patients treated with anthracyclines-based chemotherapy regimens. Furthermore,overexpression of SIRT6 alleviated doxorubicin-induced cytotoxicity in cardiomyocytes, and potentiated cytotoxicity of doxorubicin in multiple cancer cell lines. Moreover, SIRT6 overexpression ameliorated doxorubicin-induced cardiotoxicity and potentiated antitumor efficacy of doxorubicin in mice, suggesting that SIRT6 overexpression could be an adjunctive therapeutic strategy during doxorubicin treatment.Mechanistically, doxorubicin-impaired mitochondria led to decreased mitochondrial respiration and ATP production. And SIRT6 enhanced mitochondrial biogenesis and mitophagy by deacetylating and inhibiting Sgk1. Thus, SIRT6 overexpression coordinated metabolic remodeling from glycolysis to mitochondrial respiration during doxorubicin treatment, which was more conducive to cardiomyocyte metabolism, thus protecting cardiomyocytes but not cancer cells against doxorubicin-induced energy deficiency. In addition, ellagic acid, a natural compound that activates SIRT6, alleviated doxorubicininduced cardiotoxicity and enhanced doxorubicin-mediated tumor regression in tumor-bearing mice.These findings provide a preclinical rationale for preventing cardiotoxicity by activating SIRT6 in cancer patients undergoing chemotherapy, but also advancing the understanding of the crucial role of SIRT6 in mitochondrial homeostasis.

Effect of moisture regime on the redistribution of heavy metals in paddy soil

Sequential extraction procedure was applied to assess the dynamics of solid-phase transformation of added Cu, Pb, Cd, and Hg in a typical Chinese paddy soil incubated under three moisture regimes （75% field capacity, wetting-drying cycle, and flooding）. The heavy metals spiked in the soil were time-dependently transferred from the easily extractable fraction （the exchangeable fraction） into less labile fractions （Fe-Mn oxide- and organic matter-bound fractions）, and thus reduced lability of the metals. No significant changes were found for the carbonate-bound and residual fractions of the heavy metals in the soil during the whole incubation. Change rate of the mobility factor （MF）, a proportion of weakly bound fractions （exchangeable and carbonate-bound） in the total metal of soil, reflected the transformation rate of metal speciation from the labile fractions toward stable fractions. It was found that soil moisture regime did not change the direction and pathways of transformation of metal speciation, but it significantly affected the transformation rate. In general, the paddy soil under flooding regime had higher metal reactivity compared with 75% field capacity and wetting-drying cycle regimes, resulting in the more complete movement of metals toward stable fractions. This might be related to the increased pH, precipitation of the metals with sulfides and higher concentration of amorphous Fe oxides under submerged condition.

Accumulation and relationship of metals in different soil aggregate fractions along soil profiles

Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determined in six sizes of aggregates(>2,2-1,1-0.6,0.6-0.25,0.25-0.053,<0.053 mm).Significantly high(p<0.05)structural stability indexes(SSI)and ag-gregate stability indexes(ASI)were recorded in the topsoil horizon,which may be attributed to the high soil organic matter(SOM)content in aggregates from topsoil.In addition,ASI and SSI were positively correlated(r=0.569,p<0.05)with each other,which indicated that the stability of soil aggregates could contribute to the structural stability of bulk soil.Moreover,accumulation factors(AF),principal component analysis(PCA)and Pearson's correlation co-efficients were used for metal element assessment.The results indicated that SOM was not a key factor affecting the accumulation of Ca,Mg,Al,Fe,Mn,Pb,Cd and Cu in soil aggre-gates.In general,AF values for metal elements in microaggregates(<0.25 mm)were high,which showed that metals preferred to accumulate in fine soil aggregates.The PCA and Pearson's correlation coefficients indicated that soil parent materials primarily controlled the distribution of Al,Ca,Fe,Mg and Mn,while materials derived from technogenic sources have important impacts on the distribution of Cd,Cu and Pb in soil aggregates along the soil profile.

Changes in profile distribution and chemical properties of natural nanoparticles in paddy soils as affected by long-term rice cultivation

Systematic studies on the genesis,properties,and distribution of natural nanoparticles(NNPs)in soil remain scarce.This study examined a soil chronosequence of continuous paddy field land use for periods ranging from 0 to 1000 years to determine how NNPs in soil changed at the early stages of soil genesis in eastern China.Soil samples were collected from coastal reclaimed paddy fields that were cultivated for 0,50,100,300,700,and 1000 years.Natural nanoparticles were isolated and characterized along with bulk soil samples(<2-mm fraction)for selected physical and chemical properties.The NNP content increased with increasing soil cultivation age at 60 g m^(-2) year-1,which was related to decreasing soil electrical conductivity(172-1297μS cm^(-1))and NNP zeta potentials(from -22 to -36 mV)with increasing soil cultivation age.Changes in several NNP properties,such as pedogenic iron oxide and total organic carbon contents,were consistent with those of the bulk soils across the soil chronosequence.Notably,changes in NNP iron oxide content were obvious and illustrated active chemical weathering,pedogenesis,and potential impacts on the microbial community.Redundancy analysis demonstrated that the soil cultivation age was the most important factor affecting NNP properties,contributing 60.7% of the total variation.Cluster and principal component analysis(PCA)revealed splitting of NNP samples into age groups of 50-300 and 700-1000 years,indicating rapid evolution of NNP properties,after an initial period of desalinization(approximately 50 years).Overall,this study provides new insights into NNP evolution in soil during pedogenesis and predicting their influences on agriculture and ecological risks over millennial-scale rice cultivation.