Experimental study of soil erosion on moraine-consolidated slopes under heavy rainfall.

Surface subsidence pits formed by mining disturbance are highly susceptible to slope instability under rainfall erosion, inducing underground debris flow disasters. To prevent and control underground debris flow disasters in a subsidence area, a test model of subsidence pit slope was established in accordance with the principle of similar simulation, and the erosion-resistant performance of moraine-cured slopes with different soil-slurry ratios and the law of runoff and sand production were investigated through the simulation of artificial rainfall and a simulation test of grouting. Results show that the initial rainfall production time increases exponentially with increasing soil-slurry ratio, while sediment production intensity decreases linearly with increasing rainfall duration. The evolution of soil erosion can be divided into five stages: impact infiltration, water-filled softening, stripping cutting, migration crossing, and steady flow equilibrium. Compared with in situ moraine, moraine particles after grouting between the generation of large amounts of Si-O-Si and Si-OH hydration products become loose and porous soil medium is transformed into a dense cemented structure. The soil-slurry ratio is 5:1, the sand-fixing effect increases by 28.8 times, the resistance of permeability increases by 11.3 times, and the grouting curing effect is remarkable. This study can provide technical support for the prevention and control of geological disasters in subsidence pits.

[Characteristics and Influencing Factors of Stable Hydrogen and Oxygen Isotopes in Groundwater in the Permafrost Region of the Source Region of the Yangtze River].

We use 84 rainfall samples collected during June to September 2017 from the Dongkemadi basin, source region of the Yangtze River, China, to analyze the characteristics and influencing factors of stable isotopes in groundwater, and further discuss the groundwater recharge sources. The results showed that the range of groundwater δ18 O values in this permafrost region varied from -15.3‰ to -12.5‰ (mean -14.0‰). The range of δD values in groundwater varied from -108.9‰ to -91.7‰ (mean -100.2‰). Compared with local atmospheric precipitation, groundwater isotopes were relatively enriched. The slope and intercept of the groundwater line (GL) in the study area were both lower than of those of the global and local meteoric water lines (GMWL and LMWL), thus indicating that groundwater in the study area was subjected to evaporation during rainfall recharge of groundwater. The d-excess values of groundwater varied from 4.9‰ to 25.0‰ (mean 11.6‰), which was close to the average d-excess value determined for global average rainfall (10‰), but lower than that of rainfall in the study area (15.1‰). The influencing factors on the composition and variation of groundwater isotopes were different in different periods. The permafrost active layer was relatively thin during periods of increasing air temperature, and groundwater isotopes were significantly affected by air temperature. A temperature decrease during the latter part of the sampling period, when the thickness of the permafrost active layer was still increasing, further increased the retention time of infiltrating rainfall in the soil, thereby eventually leading to evaporation that strengthened the enrichment of heavy isotopes in the groundwater. According to the topographic characteristics of the Dongkemadi basin, the isotopic characteristics of the groundwater, and the factors influencing the isotopic composition, we conclude that rainfall was the main source of groundwater recharge. The results of this study provide a scientific basis for studying water cycle processes in the permafrost regions of the source region of the Yangtze River.

[Characteristics of Stable Isotopes in Precipitation and Moisture Sources in the Headwaters of the Yangtze River].

Based on the stable isotopes of 73 precipitation samples continuously collected from May to October 2014 and related meteorological statistics in the Dongkemaldi Basin, the characteristics of δD, δ18O, and d-excess of precipitation, as well as the correlations between δ18O and the rainfall amount and air temperature were analyzed. The moisture sources were tracked by the HYSPLIT model to further estimate the contribution of different water vapor sources to the rainfall amount. The results showed that the range of δ18O and δD values varied from -26.5‰ to 1.9‰ and -195.2‰ to 34.0‰, respectively; meanwhile, the δ18O and δD values in precipitation fluctuated greatly with time in response to water vapor transport from different moisture sources of the Qinghai-Tibet Plateau. The slope and intercept of the Local Meteoric Water Line (LMWL) were both higher than those of the Global Meteoric Water Line (GMWL) and close to the LMWL in the northern area of the Qinghai-Tibet Plateau. The relationship between δ18O and δD in different precipitation types showed significant differences, which were mainly related to the source of water vapor and meteorological conditions during the process of precipitation formation. Because of the influence of local evaporation and the transport process of water vapor, the d-excess values of atmospheric precipitation were relatively large; the δ18O in precipitation had a significant amount effect, but had no temperature effect, thus indicating that the rainfall amount was more effective in controlling the stable isotope content of atmospheric precipitation than temperature. The modeled trajectory of vapor sources showed that water vapor of precipitation was mainly derived from the marine vapor carried by the southwest monsoon, local moisture, and the westerly water vapor, and their contributions to the rainfall amount were 43%, 36%, and 21%, respectively. The results of this study can contribute to further understanding of the atmospheric circulation characteristics and water cycle process of the Dongkemadi basin in the headwaters of the Yangtze River.

[Chemical Characteristics and Ionic Sources of Precipitation in the Source Region of the Yangtze River].

Using 64 precipitation samples collected from June to September 2013 in the Dongkemadi Basin in the source region of the Yangtze River, the pH, conductivity, and main ionic concentration characteristics of precipitation were analyzed. The main ionic sources of precipitation and their relationships with atmospheric circulation were examined using factor analysis, correlation analysis, enrichment factor analysis, and backward trajectory analysis. The results showed that the range of precipitation pH values varied from 5.26 to 9.25 with a weighted average of 6.70, and conductivity ranged from 0.23 to 28.70 µS·cm-1 with a weighted average of 3.45 µS·cm-1. The conductivity of precipitation was lower than for the Mt. Waliguan basin (China Global Atmosphere Watch baseline observatory). The total ionic concentrations in the precipitation ranged from 7.0 to 376.9 µeq·L-1 with a weighted average of 40.8 µeq·L-1. The ranked order of ionic concentrations was HCO3- > NH4+ > Ca2+ > NO3- > SO42- > Na+ > Cl- > K+ > Mg2+. HCO3-, NH4+,Ca2+, and NO3- were the dominant ions, which accounted for 74.75% of the total ionic concentration. Fractional acidity (FA) analysis showed that 97.8% of the precipitation acidity was neutralized by alkaline constituents. Neutral factor (NF) analysis indicated that NH4+ and Ca2+ were the dominant neutralization constituents in the precipitation. The precipitation ions in this study area were mainly derived from terrestrial material, while input from marine sources was relatively low. Backward trajectory analysis revealed that the total ionic concentrations varied significantly between the different sources, which followed the order of local sources>westerly sources>monsoon sources. This indicates that different atmospheric circulation conditions and air mass sources have a significant influence on the chemical composition of precipitation in this area. To some extent, the chemical characteristics of precipitation could reflect the air quality and background values for remote areas due to the limited effect of human activities. The results of this study provide a scientific basis for the protection of water quality and the assessment of the impact of human activities on the atmospheric environment in the source region of the Yangtze River.

Comparisons of short-term and survival outcomes of laparoscopy-assisted versus open total gastrectomy for gastric cancer patients.

OBJECTIVES: The safety and surgical oncology of laparoscopy-assisted total gastrectomy (LATG) remain inconclusive and challenging. This study aimed to compare the short-term and long-term outcomes between LATG and open total gastrectomy (OTG) procedures. RESULTS: In the all-included analyses, there were 69 patients in the LATG group and 268 in the OTG group. LATG was as safe as OTG without increasing postoperative morbidity and mortality. Stage imbalance might introduce differences in the numbers of harvested lymph nodes in LATG (34.4 ± 12.0) and OTG (40.9 ± 16.9), whereas 95.7% of patients underwent D2/D2+ dissection during the LATG procedure. After a median 31 months of follow-up, the overall survival outcomes were comparable between the LATG and OTG procedures (HR = 1.16, 95% CI 0.68-1.97). Sensitivity analysis found comparable node retrieval and stage-specific or treatment-specific overall survival. MATERIALS AND METHODS: A retrospective case-control study was conducted among gastric cancer patients who underwent either LATG or OTG with curative intention between June 2006 and December 2015. Data retrieval was based on the Surgical Gastric Cancer Patient Registry in the West China Hospital. The primary outcome was overall survival. The secondary outcomes were postoperative complication incidence and severity, operation duration, blood loss, number of harvested lymph nodes, and postoperative hospital stay. Matched pairwise case-control comparisons were performed as a sensitivity analysis. CONCLUSIONS: LATG by experienced surgeons possibly has comparable short-term surgical outcomes and long-term survival outcomes compared with OTG for gastric cancer patients. However, high-quality RCTs are necessary before confirmative judgment and recommendation as an optional treatment in general practice.

[Expression and significance of Slug, E-cadherin and N-cadherin in gastrointestinal stromal tumors].

OBJECTIVE: To explore the expression and clinical significance of Slug, E-cadherin and N-cadherin in gastrointestinal stromal tumors (GIST). METHODS: Seventy eight GIST specimens removed surgically from 2004 to 2007 were collected from the Department of Gastrointestinal Surgery at Guizhou Provincial People's Hospital. There were 48 males and 30 females with an age range of 28 - 87 years old. The expressions of Slug, E-cadherin and N-cadherin in GIST were determined by immunohistochemistry. And the correlations with their clinicopathologic characteristics were analyzed. RESULTS: The positive rates of Slug, E-cadherin and N-cadherin in GIST were 53.8% (42/78), 35.9% (28/78) and 75.6% (59/78) respectively. And the differences were statistically significant (χ(2) = 24.98, P < 0.05). Slug was expressed markedly higher in the cases of GIST with distant metastasis or distant metastasis and local invasion: 75% (18/24) vs 44.4% (24/54), 63.6% (28/44) vs 41.2% (14/34), both P < 0.05. And E-cadherin was expressed markedly lower in the cases of GIST with distant metastasis: 16.7% (4/24) vs 44.4% (24/54), P < 0.05. The expression of N-cadherin was not significantly different between its clinicopathological characteristics (allP > 0.05). The expression of Slug correlated negatively with that of E-cadherin (r(s) = -0.267, P = 0.018). But it had no correlation with that of N-cadherin (r(s) = 0.056, P = 0.625). CONCLUSION: Slug is expressed markedly higher while E-cadherin markedly lower in metastatic GIST, and both are closely correlated with the metastasis of GIST.

Gastrosplenic fistula due to splenic large B-cell lymphoma.

A gastrosplenic fistula (GSF) is an unusual complication arising from a variety of primary gastric or splenic malignant lesions and less commonly from benign diseases. Splenic large cell lymphoma may be a main cause of this distinctive complication. We report a case of 62-year-old male with spontaneous GSF due to pathologically proven splenic large cell lymphoma who was diagnosed by computed tomography and treated successfully by surgical management.

[Laparoscopic radical cystectomy with orthotopic ileal neobladder in the treatment of invasive bladder cancer].

OBJECTIVE: To study the technique and outcomes of laparoscopic radical cystectomy (LRC) and evaluate the efficacy of the urinary reservoir constructed with ileum in patients with invasive bladder cancer. METHODS: From 2005 - 2010, A total of 11 patients with bladder cancer were enrolled in this study. Laparoscopy was performed with 5 trocars. Urodynamic examination was performed, the function of upper urinary tract was tested, and complications were evaluated in all the eleven cases. RESULTS: The mean operation time was 420 minutes (ranged 350 to 490 min) and mean blood loss was 410 ml (ranged 300 to 700 ml). Ten of the 11 patients had complete continence, and one case had incontinence. The average flow rate was 11.5 ml/s. The first pressure of the reservoir was 29 cm H2O, and the maximum pressure was 36 cm H2O. The average capacity was 162 ml and 410 ml, respectively. The outlet pressure was 49 cm H2O. The volume of residual urine was 0 - 35 ml. No evidence of ureteral reflux was noted. CONCLUSIONS: Laparoscopic radical cystectomy is a promising method for the treatment of bladder cancer. Orthotopic ileal neobladder is considered as an ideal form of urinary diversion characterized with low pressure, larger capacity and continence.

[Meta-analysis of laparoscopic and open repair of perforated peptic ulcer].

OBJECTIVE: To assess the safety and feasibility of laparoscopic and open repair of perforated peptic ulcer. METHODS: Studies on comparison between laparoscopic repair(LR) and open repair(OR) of perforated peptic ulcer were collected. Data of operating time, blood loss, time to first flatus, postoperative hospital stay, postoperative complications and mortality between LR group and OR group were meta-analyzed using fixed effect model and random effect model. RESULTS: Nineteen studies including 1507 patients were selected for this study,including laparoscopic surgery(n=673) and open surgery(n=834). There were significant differences in blood loss, time to first flatus, postoperative hospital stay, wound infection rate and mortality between LR group and OR group. However, no significant differences existed in operative time, postoperative sepsis, pulmonary infection, abdominal abscess, and suture leakage between the two groups. CONCLUSIONS: Laparoscopic repair of perforated peptic ulcer is associated with improved outcomes in terms of less blood loss, quicker recovery, and lower rates of wound infection and mortality. Laparoscopic repair of perforated peptic ulcer is safe and feasible.