Dynamic characterization of water hammer in gangue fly ash slurry pipelines during valve closure.

In the process of coal-filling mining, the gangue fly-ash slurry (GFS) needs to be transported over a long distance to reach the gobs. The abrupt closure of the valve during the transportation of GFS can result in a water hammer that significantly endangers the stability and safety of the pipeline transport system. To study the fluctuations in pressure induced by abrupt closure of the valve, experiments on the rheological parameters of gangue-coal ash slurry were conducted. Transient numerical simulations were carried out using the computational fluid dynamics method for various valve closing times. The results indicate that, with the increase of slurry concentration, the yield stress of the slurry significantly increases. When the concentration exceeds 76%, the increase in yield stress reaches 38.4% and 35.1%, respectively. Upon valve closure, the internal pressure of the slurry in the pipeline exhibits periodic dynamic oscillations. As the duration of valve closure increases, the frequency of periodic water hammer events decreases. The maximum water hammer pressure caused by valve closure decreases with the increasing distance between the valve and the closure point. At the same time, the intensity of maximum water hammer pressure fluctuations increases with the increase in slurry concentration and flow velocity in the pipeline. The results can provide references for water hammer protection and pipeline selection during the transportation of backfill slurry in mining.

Study on mechanical properties and damage characteristics of rice straw fiber-reinforced cemented tailings backfill based on energy evolution.

Low-cost and underutilized plant fibers can affect the mechanical behavior of cementitious materials such as cemented tailings backfill (CTB). This paper attempts to explore the mechanical properties and damage evolution characteristics of rice straw fiber (RFS)-reinforced CTB (RSFCTB) from the perspective of energy. A series of mechanical and microscopic tests were carried out on CTB and RSFCTB samples. On this basis, the energy evolution law and of the filling body under different stress paths were analyzed. Meanwhile, a damage variable based on dissipation energy was established, and the damage evolution process of the filling body was discussed. The results show that uniaxial compressive strength (UCS) of filling body first grew and then dropped with the enhancement of RSF content, and indirect tensile strength (ITS) was positively correlated with RSF content. Scanning electron microscope showed that RSF was encapsulated by hydration products, which promoted the bridging effect of RSF. The bridging effect of RSF improved the integrity of RSFCTB after compression failure and resulted in bending and asymmetric tensile cracks after tensile failure. The energy storage limit and dissipation energy of the filling body under different stress paths were enhanced due to the incorporation of RSF. The damage curve based on dissipation energy showed three stages of slow, steady, and fast damage under compressive loading. The damage curve of RSFCTB was located below CTB depending on the crack arresting effect of RSF. Moreover, the damage curve under tensile load shows three stages: slow, stable damage, and sudden increase in damage. The damage value of RSFCTB at the mutation point was increased, and the ability of RSFCTB to resist tensile damage was enhanced. The energy evolution and acoustic emission parameters were combined, and their development trends were similar, which proved that it was reasonable to characterize the damage of filling body based on the dissipated energy.

Analysis on mechanical properties and mesoscopic acoustic emission characteristics of prefabricated fracture cemented paste backfill under different loading rates.

The mechanical characteristics of cemented paste backfill (CPB) are significantly influenced by the loading rate (LR) and initial defects. Therefore, the CPB with prefabricated fracture (PF, PFCPB) was prepared, and uniaxial compressive strength (UCS) tests considering LR and acoustic emission (AE) monitoring were performed. The particle flow code (PFC2D) was introduced to analyze the mesoscopic crack evolution of the filling body, and the moment tensor theory was used to invert the AE signals characteristics. The results show that as the PF angle increased, the UCS and elastic modulus (EM) of PFCPB decreased and then increased, and the 30° PF was the turning point. The mechanical properties of PFCPB were deteriorated by the presence of PF. Meanwhile, the mechanical properties of PFCPB were positively correlated with the LR. The stress-strain curve of PFCB (excluding 90°) showed bimodal curves. After the UCS test, the macro crack of PFCPB sprouted at the tip of PF or converged toward PF. PFCPB mainly suffered from shear failure, accompanied by a few tensile failures. Numerical simulation results showed that the crack initiation stress of PFCPB was reduced by the PF. The number of cracks first dropped and then gradually increased when the PF angle was enhanced, while gradually increased with the LR increased. Meanwhile, the mesoscopic AE characteristics of CPB were strongly in line with the test results. The AE events of 0 ~ 60° PFCPB experienced two slow rising periods and rapid rising periods. The temporal and spatial distribution characteristics of AE corresponded to the crack evolution trend. The PF was prone to stress concentration, especially at the tip and upper and lower surfaces of 0 ~ 45° PF, resulting in rapid crack initiation and reducing the energy storage limit and mechanical behavior of 0 ~ 45° PFCPB. The increasing LR (within a certain range) was in favor of improving the mechanical behavior of the filling body. The research results can provide a basic reference for the stability evaluation of the filling body with initial defects.

Mesoscopic damage evolution and acoustic emission characteristics of cemented paste backfill under different loading rates.

The cemented paste backfill (CPB) has a significant loading rate (LR) effect. The damage evolution process of CPB is closely related to the characteristics of acoustic emission (AE). This paper analyzes the damage evolution law of the filling body under different loading rates using indoor test and numerical simulations. We introduce the moment tensor theory to simulate the AE characteristics of the whole process of filling loading and explore the LR effect of the backfill with the help of the energy conservation. The results indicate the following: (1) when LR increases from 0.1 to 2 mm/min, the UCS of the backfill first increases and then decreases, contributing to the occurance of the critical LR. (2) There are no microcracks occurred in the backfill at the initial stage of loading, and the microcracks increase slowly, which is not obviously affected by LR. After the peak value, the microcracks in backfill expand and propagat rapidly to form mesoscopic cracks. (3) The mesoscopic AE events based on the moment tensor theory are in good agreement with the laboratory tests results, which can be divided into the initial period, quiet period, slow raising period, rapid raising period, and rapid falling period. (4) The temporal and spatial distribution characteristics of AE are consistent with the evolution law of microcracks. There are fewer AE events before the peak value, and AE events increase significantly and frequently with large magnitude events after the peak value. AE events dense zone and AE events with larger magnitude increase under higher LR. (5) Besides, the boundary energy and dissipation energy also gradually increased; at the same time, the strain energy first increased and then decreased. The results can provide a reference for understanding the damage evolution characteristics of backfill by different LR and AE mesoscopic simulation.

Mechanical properties of cemented tailings backfill containing alkalized rice straw of various lengths.

The tailings and rice straw that are produced in large quantities each year in the mining and agricultural industries, respectively, have significant effects on the ecological environment. This study aimed to explore the mechanical properties of cemented tailings backfill (CTB) mixed with alkalized rice straw (ARS) of different lengths. A series of uniaxial compressive strength (UCS) and indirect tensile strength (ITS) tests were conducted on the CTB. The results indicated that as the length of the ARS increased from 3 to 15 mm, the UCS and ITS values initially increased and then decreased. The critical length of the ARS was 12 mm, for which the effect of strength increase was the most significant. From the overall analysis, the UCS of CTB samples with ARS (9 and 12 mm) demonstrated the better improvement (increased by 10.0 and 14.7%, respectively) at 28 d curing age, and the improvement effect of the CTB samples with ARS of other lengths was not ideal. The ITS of CTB samples with ARS increased (except for an ARS length of 3 mm) regardless of the curing age; the maximum increase was approximately 24.2% at 28 d. The integrity, residual strength, and toughness of CTB sample with the ARS (12 mm) were the largest after the UCS test. Scanning electron microscopy (SEM) tests indicated that the surface of the ARS was covered with cement hydration products, and the interior of the ARS was filled with cement tailings, which produced stronger adhesion between the ARS (12 mm) and CTB matrix; the ARS performed a bridging role and suppressed crack propagation, which effectively improving the mechanical properties of CTB. Significantly short ARS exhibited a lower adhesive force with the matrix, and significantly long ARS exhibited a lower filling rate. Thus, while improving the mechanical properties of CTB, ARS provides a new method for treating rice straw and decreasing its combustion pollution.

LINC00467 promotes cell proliferation and metastasis by binding with IGF2BP3 to enhance the mRNA stability of TRAF5 in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) has been recognized as a member of the most common human malignant tumors globally. According to multiple studies, long noncoding RNAs (lncRNAs) have been defined as vital regulators in tumor progression. Although previous studies have indicated that lncRNA long intergenic non-protein coding RNA 467 (LINC00467) exerts oncogenic effect in tumorigenesis and the development of cancers, the specific function that LINC00467 induces in HCC remains obscure. METHODS: LINC00467 expression was examined by a quantitative reverse transcriptase-polymerase chain reaction. CCK-8, EdU, transwell, western blotting and caspase-3 activity analyses were utilized to testify the role of LINC00467 in HCC. The interaction between IGF2BP3 and LINC00467 (or TRAF5) was investigated by luciferase reporter, RIP and RNA pull-down assays. RESULTS: LINC00467 upregulation in HCC tissues and cells was observed. LINC00467 silencing suppressed cell proliferation and metastasis, whereas it facilitated cell apoptosis in HCC. The gene for tumor necrosis factor receptor-associated factor 5 (TRAF5) was a neighboring gene of that for LINC00467 and its expression was positively modulated by LINC00467 in HCC. TRAF5 knockdown inhibited HCC progression. LINC00467 deficiency could decrease the mRNA stability of TRAF5 in HCC. Insulin-like growth factor-2 messenger RNA-binding protein 3 (IGF2BP3) could bind with LINC00467 and its depletion could lower TRAF5 mRNA stability in HCC. Final rescue assays further indicated that downregulation of IGF2BP3 or TRAF5 acted against LINC00467 upregulation-mediated function on HCC progression. CONCLUSIONS: LINC00467 promotes cell proliferation and metastasis by binding with IGF2BP3 to enhance the mRNA stability of TRAF5 in HCC.

Clinical Study on Using 125I Seeds Articles Combined with Biliary Stent Implantation in the Treatment of Malignant Obstructive Jaundice.

Aim: To study the feasibility and curative effect of 125 I seeds articles combined with biliary stent implantation in the treatment of malignant obstructive jaundice. Patients and Methods: Fifty patients with malignant obstructive jaundice were included. Twenty-four were treated by biliary stent implantation combined with intraluminal brachytherapy by 125I seeds articles as the experimental group, while the remaining 26 were treated by biliary stent implantation only as the control group. The goal of this study was to evaluate total bilirubin, direct bilirubin and tumor markers (cancer antigen (CA)-199, CA-242 and carcinoembryonic antigen (CEA)), as well as biliary stent patency status and survival time before and after surgery. Results: Jaundice improved greatly in both groups. The decreases of CA-199 and CA-242 had statistical significance (p=0.003 and p=0.004) in the experimental group. The ratio of biliary stent patency was 83.3% (20/24) in the experimental group and 57.7% (15/26) in the control group (p=0.048). The biliary stent patency time in the experimental group was 1~15.5 (mean=9.84) months. The biliary stent patency time in the control group was 0.8~9 (mean=5.57) months, which was statistically significant (p=0.018). The median survival time was 10.2 months in the experimental group, while 5.4 months in control group (p<0.05). Conclusion: 125 I seeds articles combined with biliary stent implantation significantly prolongs biliary stent patency time and survival time for patients with malignant obstructive jaundice possibly by inhibiting the proliferation of vascular endothelial cells and the growth of tumor.

Microwave Ablation: The Differences Between Biliary Cirrhosis and Normal Porcine Liver Using a Cooled-tip Electrode.

AIM: To elucidate the difference in both in vivo and ex vivo microwave ablation in a biliary cirrhotic porcine liver model using a cooled-tip electrode. MATERIALS AND METHODS: Microwave ablation with cooled-tip electrode was conducted under laparotomy. Morphological and pathological characteristics of the ablated areas were compared. RESULTS: In the cirrhotic liver group, the in vivo ablated area was smaller than that ex vivo in terms of short and long axes, and volume. With the same ablation settings, both in vivo and ex vivo ablated areas in normal pig liver were larger than their counterparts in cirrhotic liver in terms of the short and long axes, and volume. CONCLUSION: Both in vivo and ex vivo ablated areas in biliary cirrhotic pig liver were smaller than their counterparts in normal liver, suggesting that for the same amount of power, it requires a significantly longer duration to achieve the same ablated volume in cirrhotic liver compared to normal liver.

Arginase inhibition protects against hypoxia­induced pulmonary arterial hypertension.

The present study aimed to determine the role of arginase (Arg) in pulmonary arterial hypertension (PAH). In vitro, human pulmonary artery smooth muscle cells (HPASMCs) were cultured under hypoxic conditions with, or without, the Arg inhibitor, S­(2­boronoethyl)­l­cysteine (BEC), for 48 h, following which the proliferation of the HPASMCs was determined using MTT and cell counting assays. For the in vivo investigation, 30 male rats were randomly divided into the following three groups (n=10 per group): i) control group, ii) PAH group and iii) BEC group, in which the right ventricle systolic pressure (RVSP) of the rats was assessed. The levels of cyclin D1, cyclin­dependent kinase (CDK)4 and p27 were measured in vitro and in vivo. The phosphorylation levels of Akt and extracellular­related kinase (ERK) were also measured in HPASMCs. In vitro, compared with the hypoxia group, Arg inhibition reduced HPASMC proliferation and reduced the expression levels of cyclin D1, CDK4, phosphorylated (p­)Akt and p­ERK. By contrast, Arg inhibition increased the expression of p27. In vivo, compared with the control group, the expression levels of cyclin D1 and CDK4 were reduced in the PAH group, however, the expression of p27 and the RVSP increased. In the BEC group, the opposite effects were observed. Therefore, it was suggested that Arg inhibition may reduce the RVSP of PAH rats and reduce HPASMC proliferation by decreasing the expression levels of cyclin D1 and CDK4, increasing the expression of p27, and partly reducing the phosphorylation of Akt and ERK.

Feasibility and efficacy of percutaneous lateral lumbar discectomy in the treatment of patients with lumbar disc herniation: a preliminary experience.

OBJECTIVE: This study was aimed at evaluating the effectiveness and safety of percutaneous lateral lumbar discectomy (PLLD) in treating patients with lumber disc herniation. METHODS: A total of 183 patients with lumbar disc herniation were recruited to receive PLLD surgery from April 2006 to October 2011. All the adverse effects were recorded during the follow-up at 1, 3, 6, and 12 months after PLLD. The clinical outcomes were determined by visual analog scale and Japanese Orthopaedic Association SCORE. RESULTS: The surgery was performed successfully in all patients (102 males and 81 females aged from 21 to 66 years) with a mean 16.6-month follow-up (range from 26 to 65 months). No postoperative complications, including intestinal and vascular complications, nerve injuries, and postoperative infections, were associated with PLLD. At one month after surgery, visual analog scale (3.12 ± 1.44 versus 6.76 ± 2.31, P<0.05) was significantly lower than the baseline and was sustained until 24 months after surgery (3.25 ± 1.78 versus 6.76 ± 2.31, P<0.05). Besides that, Japanese Orthopaedic Association score (25.25 ± 3.21 versus 11.78 ± 2.38, P<0.05) was increased when compared to the baseline. CONCLUSIONS: PLLD was a promising, mini-invasive, and effective treatment for lumber disc herniation.