Search Results (8)

Mucinous cystic neoplasm of the liver (MCN-L) is a rare benign tumor accounting for less than 5% of all liver cysts, with MCN-L in the hilar region being exceptionally uncommon and often misdiagnosed due to its complex presentation. A 48-year-old woman presented with obstructive jaundice following initial laparoscopic drainage of hepatic cysts, where pathology initially indicated benign cystic lesions. Months later, imaging revealed an enlarged cystic lesion in the left liver lobe with intrahepatic bile duct dilation. Further evaluations, including ultrasound, enhanced CT, and MRI, confirmed a large cystic lesion compressing the intrahepatic bile ducts. After a multidisciplinary discussion, hepatic cyst puncture and drainage were performed, temporarily alleviating jaundice. However, she returned with yellowish-brown drainage fluid and worsening jaundice, prompting cyst wall resection. Postoperative pathology confirmed MCN-L. Three months later, jaundice subsided, and a hepatic resection of segment 4 was performed, with pathology confirming low-grade MCN-L. At a 12-month follow-up, the patient showed no abnormalities. This case highlights the diagnostic and therapeutic challenges of MCN-L in the hilar region, as it can easily be mistaken for other liver cystic lesions on imaging. Pathologic examination is essential for definitive diagnosis, and early radical surgical resection is critical to improve prognosis and reduce the risk of malignancy and recurrence. Full article

Background: Oblique lumbar interbody fusion (OLIF) is a minimally invasive technique used to manage degenerative lumbar conditions. The presence of vacuum phenomenon (VP) and associated endplate sclerosis may increase the risk of cage subsidence. This study evaluated the relationship between VP grade, endplate sclerosis, and subsidence in OLIF. Methods: This retrospective cohort study included 165 patients who underwent a single-level OLIF for lumbar stenosis. Patients were stratified into VP grades (0–3) based on preoperative computed tomography scans. Disc height, endplate sclerosis, and cage subsidence were radiologically assessed. Clinical outcomes, including back and leg pain visual analog scale, Oswestry Disability Index, and EuroQol-5 Dimension, were measured preoperatively and at follow-up. Results: High VP grades were associated with low preoperative disc height and increased endplate sclerosis. Although no significant differences in clinical outcomes or final fusion rates across VP grades were observed, the subsidence rate increased with VP grade, with a significant difference between VP grades 1 and 2 (p = 0.045) and between VP grades 2 and 3 (p = 0.032), indicating that subsidence rates increased as the VP grade advanced. Conclusions: High VP grades, particularly grades 2 and 3, may increase the risk of cage subsidence following OLIF. Therefore, VP grading may be worth considering during surgical planning to reduce the subsidence risk and improve outcomes. Full article

Soil stabilization is a critical step in numerous engineering projects, preventing soil erosion, increasing soil strength, and reducing the risk of subsidence. Due to its inexpensive cost and potential environmental benefits, waste materials, such as waste marble powder (WMP), have been used as additives for soil stabilization in recent years. This study investigates waste marble powder’s effects on unconfined compressive strength (UCS) and clayey soil’s ultrasonic pulse velocity (UPV) at different water contents and curing times, and artificial neural networks (ANNs) are also used to predict the UCS and UPV values based on three input variables (percentage of waste marble dust, curing time, and moisture content). Geo-engineering experiments (Atterberg limits, compaction characteristics, specific gravity, UCS, and UPV) and analytical methods (ANNs) are used. The study results indicate that the soil is high-plasticity clay (CH) using the Unified Soil Classification System (USCS), and adding waste marble powder (WMP) can significantly improve the UCS and UPV of clay soils, especially at optimal water content, curing times of 28 days, and 60% WMP. It is found that the ANN models accurately predict the UCS and UPV values with high correlation coefficients approaching 1. In addition, this study shows that the optimum water content and curing time for stabilized clay soils depend on the grade and amount of waste marble powder utilized. Overall, the study demonstrates the potential of waste marble dust as a soil stabilization additive and the usefulness of ANNs in predicting UCS and UPV values. This study’s results are relevant to engineers and researchers working on soil stabilization projects, such as foundations and backfills. They can contribute to the development of sustainable and cost-effective soil stabilization solutions. Full article

As a representative city located in the Loess Plateau region of China, Lanzhou is affected by various environmental and engineering factors, such as precipitation, earthquake subsidence, and building construction, which all lead to frequent geological disasters. Obtaining information on land subsidence over a long time series helps us grasp the patterns of change in various types of ground hazard. In this paper, we present the results of using Interferometric Synthetic Aperture Radar (InSAR) to monitor land subsidence in the main urban area of Lanzhou from 26 October 2014 to 12 December 2021. The main influential factors leading to subsidence were analyzed and combined via machine learning simulation to assess the land subsidence risk grade distribution of a building unit. The results show that the annual average deformation rate in Lanzhou ranged from −18.74 to 12.78 mm/yr. Linear subsidence dominated most subsidence areas in Lanzhou during the monitoring period. The subsidence areas were mainly distributed along the Yellow River, the railway, and villages and towns on the edges of urban areas. The main areas where subsidence occurred were the eastern part of Chengguan District, the railway line in Anning District, and the southern parts of Xigu District and Qilihe urban area, accounting for 38.8, 43.5, 32.5, and 51.8% of the area of their respective administrative districts, respectively. The random forest model analysis results show that the factors influencing surface subsidence in Lanzhou were, in order of importance, precipitation, the distribution of faults, the lithology of strata, high-rise buildings, and the distance to the river and railway. Lanzhou experienced excessive groundwater drainage in some areas from 2015 to 2017, with a 1 m drop in groundwater and 14.61 mm surface subsidence in the most critical areas. At the same time, extensive subsidence occurred in areas with highly compressible loess ground and most railway sections, reaching a maximum of −11.68 mm/yr. More than half of the super-tall building areas also showed settlement funnels. The area at a very high risk of future subsidence in Lanzhou covers 22.02 km², while the high-subsidence-risk area covers 54.47 km². The areas at greatest risk of future subsidence are Chengguan District and Qilihe District. The city contains a total of 51,163 buildings in the very high-risk area, including about 44.57% of brick-and-timber houses, 51.36% of old housing, and 52.78% of super-tall buildings, which are at especially high risk of subsidence, threatening the lives and properties of the population. The deformation results reveal poor building safety in Lanzhou, providing an essential basis for future urban development and construction. Full article

The subsidence pond is an important water resource for coal mining areas in China. In order to take full advantage of the subsidence pond, a floating photovoltaic cover or a pillaring photovoltaic cover were installed on the surface water of the subsidence pond in the Huainan coal field. Different photovoltaic systems (floating/pilling cover) equipped in the subsidence pond may affect the water quality; thus, assessing the metals in the subsidence pond with the solar photovoltaic system is of great importance for environment control. In this research, surface water samples were collected from three different subsidence ponds, with or without the solar photovoltaic system. The concentrations of Pb, Cr, Ni, Cu, As, Mn, and Zn in the water of the subsidence pond were determined using ICP-MS and AFS. Then, the health risk posed by the heavy metal in different subsidence pond waters via the ingestion pathway was evaluated and analyzed using the assessment model recommended by USEPA. The results indicated that the mean concentrations of Pb, Cr, Ni, Cu, As, Mn, and Zn in the water of different subsidence ponds were less than the environmental quality standards for surface water (China, Grade II). Cr showed a higher non-carcinogenic risk than the other metals, and the photovoltaic cover actually decreased the total non-carcinogenic risk in the photovoltaic subsidence pond compared with the natural subsidence pond. Non-carcinogenic risks of single and total heavy metals in the subsidence ponds with or without solar photovoltaic systems were below 1; thus, these risks in different subsidence ponds were considered to be at an acceptable level. However, the potential single carcinogenic risks of Cr, Ni, and As; and the multielement carcinogenic risks of Pb, Cr, Ni, and As exceeded the limits of 1 × 10⁻⁶ and 1 × 10⁻⁴, respectively, suggesting that these metals showed single and total potential health risks in the subsidence pond, with or without the solar photovoltaic system. Further, the subsidence pond with the photovoltaic cover showed higher total carcinogenic risks in comparison with the natural subsidence pond. Therefore, a subsidence pond with a solar photovoltaic system should be monitored periodically to ensure the water safety. Full article

Spinal fusion surgery for end-stage renal disease (ESRD) patients is a clinical challenge. This study aimed to investigate whether postoperative radiological outcomes are related to preoperative serum calcium, phosphate, or intact parathyroid hormone (iPTH) levels in patients with ESRD who underwent spinal interbody fusion surgery. This study included 62-consecutive patients with ESRD who underwent anterior cervical discectomy and fusion (ACDF) or transforaminal lumbar interbody fusion (TLIF) surgery for symptomatic spinal disorder. The most recent preoperative serum calcium, phosphate, and iPTH levels were recorded, and the postoperative radiographic outcomes were assessed. A significant correlation was found between the occurrence of cage subsidence and higher blood phosphate, calcium–phosphate product (Ca × P), and iPTH levels in the TLIF group. The occurrence of pedicle screw loosening was related to higher blood phosphate and Ca × P product in the TLIF group. However, no correlation was found between the fusion grades and the serum levels in either the TLIF or ACDF groups. These results indicated that higher preoperative serum phosphate and Ca × P product are risk factors for both cage subsidence and screw loosening in patients with ESRD who underwent TLIF surgery. Higher iPTH levels are also a possible risk factor for cage subsidence. Full article

In Zaruma city, located in the El Oro province, Ecuador, gold mines have been exploited since before the colonial period. According to the chroniclers of that time, 2700 tons of gold were sent to Spain. This exploitation continued in the colonial, republican, and current periods. The legalized mining operation, with foreign companies such as South Development Company (SADCO) and national companies such as the Associated Industrial Mining Company (CIMA), exploited the mines legally until they dissolved and gave rise to small associations, artisanal mining, and, with them, illegal mining. Illegal underground mining is generated without order and technical direction, and cuts mineralized veins in andesitic rocks, volcanic breccia, tuffs and dacitic porphyry that have been intensely weatherized from surface to more than 80 meters depth. These rocks have become totally altered soils and saprolites, which have caused the destabilization of the mining galleries and the superficial collapse of the topographic relief. The illegal miners, called "Sableros", after a period of exploitation at one site, when the gold grade decreased, abandon these illegal mines to begin other mining work at other sites near mineralized veins or near legalized mining galleries in operation. Due to this anthropic activity of illegal exploitation through the mining galleries and “piques” that remain under the colonial center of the city, sinkings have occurred in various sectors detected and reported in various technical reports since 1995. The Ecuadorian Government has been unable to control these illegal mining activities. The indicators of initial subsidence of the terrain are small movements that accumulate over a time and that can be detected with InSAR technology in large areas, improving the traditional detection performed with geodetic instrumentation such as total stations and geodetic marks. Recent subsidence at Fe y Alegría-La Immaculada School, the city’s hospital and Gonzalo Pizarro Street, indicates that there is active subsidence in these and other sectors of the city. The dynamic triggers that have possibly accelerated the rate of subsidence and landslides on the slopes are earthquakes (5 to 6 Mw) and heavy rains in deforested areas. Although several sinks and active subsidence caused by underground mining were detected in these sectors and in other sectors in previous decades, which were detailed in various reports of geological hazards prepared by specialized institutions, underground mining has continued under the colonial city center. In view of the existing risk, this article presents a forecasting methodology for the constant monitoring of long-term soil subsidence, especially in the center of the colonial city, which is a national cultural heritage and candidate for the cultural heritage of humanity. This is a proposal for the use of synthetic aperture radar interferometry (InSAR) for the subsidence analysis of topographic relief in the colonial area of the city of Zaruma by illegal mining galleries. Full article

Subsidence at abandoned mines sometimes causes destruction of local areas and casualties. This paper proposes a mine subsidence risk index and establishes a subsidence risk grade based on two separate analyses of A and B to predict the occurrence of subsidence at an abandoned mine. For the analyses, 227 locations were ultimately selected at 15 abandoned coal mines and 22 abandoned mines of other types (i.e., gold, silver, and metal mines). Analysis A predicts whether subsidence is likely using an artificial neural network. Analysis B assesses a mine subsidence risk index that indicates the extent of risk of subsidence. Results of both analyses are utilized to assign a subsidence risk grade to each ground location investigated. To check the model’s reliability, a new dataset of 22 locations was selected from five other abandoned mines; the subsidence risk grade results were compared with those of the actual ground conditions. The resulting correct prediction percentage for 13 subsidence locations of the abandoned mines was 83–86%. To improve reliability of the subsidence risk, much more subsidence data with greater variations in ground conditions is required, and various types of analyses by numerical and empirical approaches, etc. need to be combined. Full article