Research on failure mechanism of landslide with retaining-wall-like locked segment and instability prediction by inverse velocity method.

The locked segment is critical for determining the stability of locked segment-type landslides. Research indicates that the volume expansion point marks the transition from the secondary creep stage to the tertiary creep stage in a landslide's evolution, and also separates the stable crack growth stage from the unstable crack growth stage in the locked segment. Identifying the volume expansion point is essential for early warning and predicting locked segment-type landslides. A series of instruments (resistance strain gauges, acoustic emission system, piezoelectric acceleration sensors, etc.) were used to conduct physical model tests of the landslide with retaining-wall-like locked segment under external load on the landslide's trailing edge. The evolution process of this landslide was analyzed through changes in slope shape and stress response characteristics. The experimental results reveal the failure mechanism of the landslide with retaining-wall-like locked segment: the upper part of the landslide thrusts and slides, the middle part squeezes and uplifts, the retaining-wall-like locked segment produces a locking effect, and compression-shear fracture of the retaining-wall-like locked segment leads to landslide failure. Based on the deformation and acoustic emission characteristics of the locked segment, a method for identifying the volume expansion point was established. This point was used as the onset of acceleration point in the inverse velocity method to predict the failure time of the locked segment-type landslides, incorporating the three-stage creep model and Fukumoto's theory.

Experimental study on tilting deformation and a new method for landslide prediction with retaining-wall locked segment.

The destruction of the locked-segment type landslide is often accompanied by the destruction of the locked segment with cumulative effects. Investigating the failure mode and instability mechanism of locked-segment type landslides is crucial. The study uses physical models to examine the evolution of locked-segment type landslides with retaining-walls. It utilizes a variety of instruments (tilt sensors, micro earth pressure sensors, pore water pressure sensors, strain gauges, and others) to conduct physical model tests of locked-segment type landslide with retaining-wall and to reveal the tilting deformation and evolution mechanism of retaining-wall locked landslide under the condition of rainfall. The results showed that the regularity of tilting rate, tilting acceleration, strain, and stress change in the retaining-wall locked segment is consistent with the landslide evolution process, indicating that tilting deformation can be used as the criterion of landslide instability and that the locked segment plays a vital role in controlling the landslide stability. The tertiary creep stages of tilting deformation are divided into initial, medium, and high tertiary creep stages using an improved angle tangent method. This establishes the failure criterion for locked-segment type landslides with tilting angles of 0.34°, 1.89°, and 4.38°. In addition, the tilting deformation curve of a locked-segment type landslide with a retaining-wall is utilized to predict the landslide instability by the reciprocal velocity method.

Stress-strain and acoustic emission characteristics of cement-based materials used to simulate soft rock with fractures.

Instability failure in rock mass engineering is closely related to expansion of joint fissures. In this study, uniaxial compression tests and acoustic emission (AE) measurements were carried out simultaneously on specimens of soft rock-like material with different fracture angles and connectivity values to better understand their influence on the deformation and failure of the material. The stress-strain curve and AE signal of fractured soft rock-like material are similar to those of intact soft rock-like; specifically, they exhibit a compaction, elastic deformation, stable fracture development, and unstable fracture development. The main differences between fractured and intact material occur during post-peak failure stage. Under the combined influence of fracture angle and connectivity, the uniaxial compressive strength of fractured soft rock-like material ([Formula: see text]) is lower than that of the intact soft rock-like material (fcu), and can be described by the relationship [Formula: see text], where [Formula: see text] is the strength reduction coefficient, fitted as [Formula: see text]. In this equation, x is the fracture angle ([Formula: see text]) and y is the fracture connectivity (%). Under uniaxial compression, the main types of secondary cracks were wing cracks and secondary coplanar cracks. The specimen with a fracture angle of 30° mainly underwent tensile failure under loading, whereas those with fracture angles of 45° and 60°mainly experienced shear failure under high-connectivity conditions (45%).

Linear Stapler versus Circular Stapler for Patients Undergoing Anastomosis for Laparoscopic Gastric Surgery: A Meta-Analysis.

BACKGROUND: Anastomotic devices, including linear staplers (LSs) and circular staplers (CSs), have been widely used after laparoscopic gastric surgery. However, it is controversial whether linear stapling is superior to circular stapling for anastomosis. Thus, we conducted a meta-analysis to compare the aspects of postoperative complications, particularly anastomotic stricture and anastomotic leakage, on the use of the two techniques to assist clinical decision-making. METHODS: We conducted a systematic search using Embase, PubMed, and Cochrane Library to evaluate studies that compared LSs and CSs after laparoscopic gastric surgery. RESULTS: Pooled analysis suggested that patients who received LSs had fewer postoperative complications (P = 0.019), and anastomotic complications (P < 0.001), stricture (P = 0.001), and bleeding (P = 0.005). The subgroup analyses showed that LSs caused fewer anastomotic complications (P < 0.001), anastomotic strictures (P < 0.001), and postoperative hemorrhage (P = 0.007) in patients with gastric cancer than CS. In addition, LSs caused fewer incidences of overall morbidity (P = 0.042), anastomotic strictures (P = 0.023), postoperative hemorrhage (P < 0.001), wound infection (P < 0.001), and shorter length of hospital stay (P = 0.048) in patients with obesity. Furthermore, the subgroup analyses showed that the use of LS resulted in lower overall morbidity (P = 0.042), anastomotic stricture (P = 0.023), wound infection (P < 0.001), length of hospital stay (P = 0.048), and postoperative hemorrhage (P < 0.001) when applied in gastrojejunostomy, while LSs resulted in fewer anastomotic complications (P < 0.001), anastomotic stricture (P = 0.016) than CS when applied in esophagojejunostomy. CONCLUSION: Compared with CSs, LSs yielded a lower incidence of overall morbidity, anastomotic complications, anastomotic stricture, bleeding, and wound infection, indicating that linear stapling is safer and more efficient than circular stapling when performing anastomosis after laparoscopic gastric surgery.

Effectiveness and safety of robotic gastrectomy versus laparoscopic gastrectomy for gastric cancer: a meta-analysis of 12,401 gastric cancer patients.

Advanced minimally invasive techniques, such as robotic surgeries, are applied increasingly frequently around the world and are primarily used to improve the surgical outcomes of laparoscopic gastrectomy (LG). Against that background, we conducted a meta-analysis to evaluate the feasibility, safety, and effectiveness of robotic gastrectomy (RG). Studies comparing surgical outcomes between LG and RG patients were retrieved from medical databases, including RCTs and non-RCTs. The primary outcome of this study was overall survival, which was obtained by evaluating the 3-year survival rate and the 5-year survival rate. In addition, postoperative complications, mortality, length of hospital stay, and harvested lymph nodes were also assessed. We also conducted subgroup analyses stratified by resection type, body mass index, age, depth of invasion and tumour size. Ultimately, 31 articles met the criterion for our study through an attentive check of each text, including 1 RCT and 30 non-RCTs. A total of 12,401 patients were included in the analysis, with 8127 (65.5%) undergoing LG and 4274 (34.5%) undergoing RG. Compared with LG, RG was associated with fewer postoperative complications (OR 0.81; 95% CI 0.71-0.93; P = 0.002), especially pancreas-related complications (OR 0.376; 95% CI 0.156-0.911; P = 0.030), increased harvested lymph nodes (WMD 2.03; 95% CI 0.95-3.10; P < 0.001), earlier time to first flatus (WMD - 0.105 days; 95% CI - 0.207 to - 0.003; P = 0.044), longer operation time (WMD 40.192 min, 95% CI 32.07-48.31; P < 0.001), less intraoperative blood loss (WMD - 20.09 ml; 95% CI - 26.86 to - 13.32; P < 0.001), and higher expense (WMD 19,141.68 RMB; 95% CI 11,856.07-26,427.29; P < 0.001). There was no significant difference between RG and LG regarding 3-year overall survival (OR 1.030; 95% CI 0.784-1.353; P = 0.832), 5-year overall survival (OR 0.862; 95% CI 0.721-1.031; P = 0.105), conversion rate (OR 0.857; 95% CI 0.443-1.661; P = 0.648), postoperative hospital stay (WMD - 0.368 days; 95% CI - 0.75-0.013; P = 0.059), mortality (OR 1.248; 95% CI 0.514-3.209; P = 0.592), and reoperation (OR 0.855; 95% CI 0.479-1.525; P = 0.595). Our study revealed that postoperative complications, especially pancreas-related complications, occurred less often with RG than with LG. However, long-term outcomes between the two surgical techniques need to be further examined, particularly regarding the oncological adequacy of robotic gastric cancer resections.

Comparison of Survival and Safety Between Total Omentectomy and Partial Omentectomy for Gastric Cancer: A Meta-Analysis.

Background: The greater omentum can limit abdominal inflammation and act as a protective cushion, but it is always involved in dissemination of gastric cancer. The purpose of this meta-analysis was to compare the survival and safety between total omentectomy and partial omentectomy for gastric cancer. Methods: Two investigators independently conducted a systematic search of PubMed, Embase, CNKI, and Cochrane Library ranging from January 2000 to November 2020. The pooled odds ratio (ORs) and weighted mean difference (WMD) with the 95% confidence interval (95% CI) were used to assess perioperative and survival parameters. Results: A total of 2,031 patients in 11 studies (574 patients in the partial omentectomy group and 1,457 patients in the total omentectomy group) were included. The results found shorter operation time (WMD = -25.584; P = 0.000) and less intraoperative blood loss (WMD = -47.301; P = 0.050) in the partial omentectomy group, compared to total omentectomy. There were no significant differences in terms of incidence of complications (OR = 0.770; P = 0.164), blood transfusions rates (OR = 0.269; P = 0.161), time to first flatus (WMD = 0.160; P = 0.345), hospital stay (WMD = -1.258; P = 0.087), and number of harvested lymph nodes (WMD = 1.265; P = 0.662). For the disease-free survival (OR = 0.80; P = 0.381) and overall survival, there were no statistical differences between the two procedures. Conclusions: The partial omentectomy could reduce operation time and trended to decrease intraoperative blood loss. And the survival in patients with partial omentectomy seemed to be comparable to that of patients with total omentectomy.

Gene expression profile for predicting survival of patients with meningioma.

Current staging methods are inadequate for predicting the overall survival of meningioma. DNA microarray technologies improve the understanding of tumour progression. We analysed genome wide expression profiles of 119 meningioma samples from two previous published DNA microarray studies. The Cox proportional hazards regression models were applied to identify overall survival related gene signature. A total of 449 genes (109 upregulated and 340 downregulated) were identified as differentially expressed in meningioma. Among these differentially expressed genes, 37 genes were identified to be related to meningioma overall survival. Our 37-gene signature is closely associated with overall survival among patients with meningioma. This gene expression profile could provide an optimization of the clinical management and development of new therapeutic strategies for meningioma.

[Application of keyhole approach in operation of intracranial aneurysms].

OBJECTIVE: To explore the operative technique and evaluate the effect of intracranial aneurysms via keyhole approach. METHODS: Fifty-six intracranial aneurysm patients, 23 with anterior communicating artery (AcomA) aneurysm, 29 with posterior communicating artery (PcomA) aneurysm, and 4 with internal carotid artery-posterior communicating artery aneurysm, totally with 58 lesions, were treated by microsurgery, via supraorbital keyhole approach in 22 cases, pterional approach in 18, and transorbital approach in 16. Adjuvant endoscopy was used in 33 patients. RESULTS: Fifty-eight lesions of aneurysm were clipped in all the patients and no one died. No approach-related severe complication occurred. Bilateral PcomA aneurysms in 2 cases were clipped via unilateral keyhole approach. CONCLUSION: It is workable to treat intracranial aneurysms via keyhole approach. Keyhole approach not only reduces the operation-related trauma and shorten the operation time, but also obtains ideal results.

[Determination of available as (III) and as (V) in soils by flow injection hydride generation atomic fluorescence spectrometry].

A method for the determination of available As (III) and As (V) in soils by flow injection hydride generation atomic fluorescence spectrometry (FI-HG-AFS) was presented. As the concentration of As (III) in extract was determined by HG-AFS in the medium of 0.1 mol.L-1 citric acid solution and the total arsenic was determined after FI on-line reduction of As (V) by L-cysteine, the concentration of As (V) was calculated by the difference. The manifolds for FI on-line reduction of As (V) were designed. The chemical conditions and the operating parameters were optimized. The detection limits (3 sigma) of As (III) and As (V) are 0.11 and 0.07 ng.mL-1, respectively, and the relative standard deviation is 1.43 for 7 determinations of 10 ng.mL-1 As (III) solution. The developed method was applied to the determination of available As (III) and As (V) in real soils and the recovery was 82%-104%.

[Rice breeding by space technology].

In order to inquire into the influences of space conditions on rice breeding,the dry seeds of 12 rice varieties were carried by recoverable satellite. After recovery,these seeds were showed in the yield, the inheritance and variation of the characters of their progenies were observed and analysed. The results showed that the characters of the progenies mutated under space conditions segregated and varied in many aspects and directions,and the segregated and varied characters were heritable. These progenies posoessed significant transgressive inheritance, a plenty of variation types and variation was characterized by short breeding period. The results in this study indicated that space technology breeding could be developed and used as a new method of mutation breeding.