Nano-sized carbides in carbon-doped high entropy alloys (HEAs) can induce remarkable precipitation strengthening, but the precipitation behavior and its effects on mechanical properties has not been ...clarified. In this study, a heavy-carbon doped equiatomic FeCoCrNiMn HEA with 1.3 at.% C addition (FeCoCrNiMn-1.3C) was prepared to provide an insight into the effect of carbides precipitation on the strength of the HEA. The results showed that FeCoCrNiMn-1.3C HEA exhibited a single FCC structure after homogenization treatment at 1220 °C for 6 h and the subsequent severe cold rolling (SCR) with 95% reduction. It was found that nano-sized M23C6 carbides can precipitate and exist stably in the SCRed FeCoCrNiMn-1.3C HEA during annealing at 700–1000 °C. These nano-sized M23C6 precipitations can substantially inhibit the recrystallized grain growth of FCC matrix in the SCRed FeCoCrNiMn HEA during annealing. The average grain size of the SCRed HEA can be maintained at 2.4 μm even after annealing at 1000 °C for 1 h due to the M23C6 precipitations inhibition on grain growth. The yield strength of ∼1040 MPa with total elongation of ∼12% has been achieved in FeCoCrNiMn-1.3C HEA after annealing at 700 °C for 1 h. Grain refinement and precipitation strengthening are the two major strengthening mechanisms of the present annealed FeCoCrNiMn-1.3C HEAs.
•A single FCC structured FeCoCrNiMn-1.3C HEA is prepared by severe cold rolling (SCR).•Nano-sized M23C6 carbides precipitate and inhibit the grain growth of the HEA during annealing at 700–1000 °C.•Grain refinement and precipitation strengthening are the two major strengthening mechanisms in the annealed HEA.
The evaluation of grouting effects constitutes a critical aspect of grouting engineering. With the maturity of the grouting project, the workload and empirical characteristics of grouting effect ...evaluation are gradually revealed. In the context of the Qiuji coal mine's directional drilling and grouting to limestone aquifer reformation, this study thoroughly analyzes the influencing factors of grouting effects from geological and engineering perspectives, comparing these with various engineering indices associated with drilling and grouting. This led to the establishment of a "dual-process, multi-parameter, and multi-factor" system, employing correlation analysis to validate the selected indices' reasonableness and scientific merit. Utilizing the chosen indices, eight high-performing machine learning models and three parameter optimization algorithms were employed to develop a model for assessing the effectiveness of directional grouting in limestone aquifers. The model's efficacy was evaluated based on accuracy, recall, precision, and F-score metrics, followed by practical engineering validation. Results indicate that the "dual-process, multi-parameter, multi-factor" system elucidates the relationship between influencing factors and engineering parameters, demonstrating the intricacy of evaluating grouting effects. Analysis revealed that the correlation among the eight selected indicators-including the proportion of boreholes in the target rock strata, drilling length, leakage, water level, pressure of grouting, mass of slurry injected, permeability properties of limestone aquifers before being grouted, permeability properties of limestone aquifers after being grouted-is not substantial, underscoring their viability as independent indicators for grouting effect evaluation. Comparative analysis showed that the Adaboost machine learning model, optimized via a genetic algorithm, demonstrated superior performance and more accurate evaluation results. Engineering validation confirmed that this model provides a more precise and realistic assessment of grouting effects compared to traditional methods.
Pipe jacking is a commonly used trenchless technology to install pipelines especially in congested urban areas or river crossings. However, the estimation of the jacking force is often heavily ...dependent on empirical calculations. The jacking force needs to be greater than the combined frictional resistance and face resistance. This investigation proposes to use a modified Protodyakonov’s arch model to compute the face resistance. A series of direct shear tests is performed to provide data of interface friction coefficient between different types of soil and pipe. The influence of slurry lubricant is also considered. A two-dimensional plane strain numerical model is conducted, where the surrounding soil is simulated as discrete particles and the lining is simplified as a single big particle. The novel modeling technique enables the evaluation of the normal force acting on the pipe. The friction resistance is then determined by multiplying the interface friction coefficient by the normal force. A ‘wavy’ shaped pipeline model is proposed to define an angular deviation influence factor to scale up the calculated jacking force due to pipe misalignment. In the end, comparison between calculated and field measured jacking force is conducted for three different drives in a pipe jacking project to illustrate the effectiveness of the proposed analysis framework.
An oversized pit-in-pit (PIP) excavation, which comprised an octagonal pit outside and two cross-shaped pits inside, was excavated in soil-rock mixed strata, Shenzhen, China. There were two shield ...tunnels connected to the north and south of the PIP excavation after the main structures completed. Extensive instruments were adopted throughout the construction process to guarantee the safety of the project. Based on the massive field data, the performance of the ground settlement, retaining structures and adjacent building deflection were investigated. Field data indicate that the influence zone of ground settlement in depth was above the stiff clay layer. The maximum lateral displacement (
δ
hm
) of the retaining structures occurred at 0.4
H
e
(
H
e
is the excavation depth), and
δ
hm
decreased when the excavation depth was over 0.5
H
e
. The maximum ground settlement
δ
vm
occurred at 0.2
H
e
which gradually decreased with
d
(
d
is the distance from the monitoring point to the excavation edge). This large discrepancy of the ground settlement induced 3.13‰ tilting of the adjacent buildings. The ground settlement influence zone was 1.7
H
e
away from the pit edge (
d
≤ 1.7
H
e
). A half-3D numerical model was established to investigate the influence of different excavation sequences. The results show that the maximum principal stress (
σ
m
) of the cover plate increased to peak value due to the excavation of subsoil, which indicated that the sidewall construction and subsoil excavation should be carried out simultaneously to reduce the stress concentration of the cover plate. TD excavation can effectively minimize the ground and building settlement, while the excavation may induce uneven displacement of the interior supporting columns. Push in failure of the sidewalls may occur during the construction which was the combined result of unloading and increase in the excavation depth.
The present study aimed to investigate whether serum growth differentiation factor 15 concentration is a valuable and reliable diagnostic biomarker of mitochondrial diseases. We examined consecutive ...patients with mitochondrial diseases, in comparison with patients with non-mitochondrial disease neuromuscular disorders and healthy controls. The serum concentrations of growth differentiation factor 15 were measured by ELISA, and compared with those of FGF21, lactate, and creatine kinase. We also evaluated the correlations between growth differentiation factor 15 concentrations and the Newcastle Mitochondrial Disease Adult Scale, numbers of ragged-red fibers, and COX-negative fibers in the biopsied muscles. The median serum growth differentiation factor 15 concentration was significantly elevated in 42 patients with mitochondrial diseases, compared with 20 patients with non-mitochondrial disease neuromuscular disorders and 50 healthy controls. The area under the curve of growth differentiation factor 15 for the diagnosis of muscle-manifesting mitochondrial diseases was 0.999, in comparison with those area under the curves of the other biomarkers including fibroblast growth factor 21 (0.935,
p
< 0.01), lactate (0.845 for
p
< 0.001), and creatine kinase (0.575,
p
< 0.001). Growth differentiation factor 15 was significantly correlated with mitochondrial disease severity and the proportion of ragged-red fibers identified in the biopsied muscles. Circulating growth differentiation factor 15 measurement is a superior biomarker with high sensitivity and specificity, which can be used as a non-invasive test to screen for primary mitochondrial diseases and dysmetabolic myopathy with associated mitochondrial dysfunction in susceptible individuals.
Application of an electronic packaging material is always limited by its established coefficient of thermal expansivity (CTE) and poor plastic working capacity. Here, we explored that a ductile ...high-entropy alloy (HEA) could achieve adjustable CTE values via decomposing at 500 °C. The carbon-doped equiatomic FeCoCrNiMn HEAs (0.8, 1.0, and 1.3 at% C) decomposed into B2, L1
0
, M
23
C
6
and
σ
phases during annealing. The adjustable CTE of the carbon-doped HEAs can be ascribed to the relatively low CTE values of the formed B2, L1
0
, M
23
C
6
, and
σ
phases. The CTE value of a single face-centered cubic (FCC)-structured FeCoCrNiMn-1.3 at% C HEA is 16.7 × 10
–6
°C
−1
, yet it can be continuously adjusted to 11.3 × 10
–6
°C
−1
when the FCC matrix is gradually decomposed into the B2, L1
0
, M
23
C
6
, and
σ
phases. Furthermore, the decomposition rate and fractions of the B2, L1
0
, M
23
C
6
, and
σ
phases can be controlled via changing carbon concentration and rolling reduction. More importantly, the CTE range of the 1.3C HEAs meets the requirements of electronic packaging. This work provides a way to design HEAs with desirable CTE for electronic industry via annealing at intermediate temperature.
Trenchless technology is often used in congested urban areas or river crossings to install underground pipelines to minimize disturbance to surface traffic or other activities. Pipe jacking is a ...typical technique applied to jack pipe segments between two working shafts. However, the design of the jacking force is usually implemented using empirical methods. It should be emphasized that the jacking force will change for each site, depending on the magnitude of overcut, lubricants, work stoppages, geology and misalignment. A particle method is proposed to estimate the jacking force along the pipe. The microparameters are calibrated for sandy soils in Shenyang, so that the macroscale material behavior can be reproduced using the particle model. Hence, the normal force around the pipe circumference can be derived in the particle model, after which the interface friction coefficient is applied to evaluate the friction resistance mobilized at the soil-pipe interface. A modified Protodyakonov’s arch model can be used to assess the magnitude of earth pressure acting on the shield face. In the end, the combination of friction resistance and face pressure provides the jacking force. The efficacy of the proposed particle method is demonstrated by comparing calculated jacking forces with those measured in the field for three types of jacking machines in sandy soils under the Hun River, Shenyang.
To explore the effects of cardiac exercise rehabilitation on peripheral blood endothelial progenitor cells (EPC) in elderly patients with chronic heart failure.
80 elderly patients with chronic heart ...failure were selected from March 2017 to March 2019 and randomly divided into two groups (N = 40). The control group was treated routinely and walked freely for 30-60 min every day. The patients in the exercise rehabilitation group developed a cardiac exercise rehabilitation plan. Then, cardiac function and peripheral blood B-natriuretic peptide (BNP) levels in the two groups were compared. The cell viability, proliferation, apoptosis, and invasion ability of EPCs were detected. The levels of the PI3K/AKT pathway and eNOS and VEGF were compared.
There were no significant differences in all indexes between the two groups before treatment (P > 0.05), and both improved significantly after treatment (P < 0.05). After treatment, LVEF and LVFS in the exercise rehabilitation group were significantly higher than those in the control group (P < 0.05), and LVEDD and LVESD were significantly lower than those in the control group (P < 0.05). The BNP level in the exercise rehabilitation group was significantly lower than that in the control group (P < 0.05). The cell viability, proliferation, invasion ability of EPC, and the levels of PI3K, AKT, eNOS, and VEGF mRNA and protein in the exercise rehabilitation group were significantly higher than those in the control group. Apoptosis rate was significantly lower than those in the control group (P < 0.05).
Visceral exercise rehabilitation can improve cardiac ejection and myocardial function in elderly patients with chronic heart failure, and can promote the vitality, proliferation, and invasion of peripheral blood EPC, and promote the expression of eNOS and VEGF by upregulating the PI3K/AKT pathway to promote angiogenesis and endothelial function.
Becker muscular dystrophy (BMD), an X-linked recessive disorder caused of mutation in the dystrophin gene, is characterized by progressive muscle degeneration and proximal muscle weakness. We ...generated a human induced pluripotent stem cell (hiPSC) line from the fibroblasts isolated from patient with BMD by non-integrating reprogramming methods. The iPSC line highly expresses pluripotency markers, displays the normal karyotype and is able to differentiate into the three germ layers in vitro. The iPSC line will be a useful tool to study the pathogenesis of BMD and for drug screening.
We have established the human induced pluripotent stem cell (hiPSC) line (INNDSUi001-A) from skin fibroblasts of a healthy 24-year-old female individual by using non-integrating reprogramming method. ...The resulted cells had typical features of embryonic stem cell as indicated by expression of specific pluripotency markers and had the capability of in vitro differentiation into the three germ layers. This iPSC line can be used as a healthy control for disease study.
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