Identification and Analysis of the Geohazards Located in an Alpine Valley Based on Multi-Source Remote Sensing Data.

Geohazards that have developed in densely vegetated alpine gorges exhibit characteristics such as remote occurrence, high concealment, and cascading effects. Utilizing a single remote sensing datum for their identification has limitations, while utilizing multiple remote sensing data obtained based on different sensors can allow comprehensive and accurate identification of geohazards in such areas. This study takes the Latudi River valley, a tributary of the Nujiang River in the Hengduan Mountains, as the research area, and comprehensively uses three techniques of remote sensing: unmanned aerial vehicle (UAV) Light Detection and Ranging (LiDAR), Small Baseline Subset interferometric synthetic aperture radar (SBAS-InSAR), and UAV optical remote sensing. These techniques are applied to comprehensively identify and analyze landslides, rockfalls, and debris flows in the valley. The results show that a total of 32 geohazards were identified, including 18 landslides, 8 rockfalls, and 6 debris flows. These hazards are distributed along the banks of the Latudi River, significantly influenced by rainfall and distribution of water systems, with deformation variables fluctuating with rainfall. The three types of geohazards cause cascading disasters, and exhibit different characteristics in the 0.5 m resolution hillshade map extracted from LiDAR data. UAV LiDAR has advantages in densely vegetated alpine gorges: after the selection of suitable filtering algorithms and parameters of the point cloud, it can obtain detailed terrain and geomorphological information on geohazards. The different remote sensing technologies used in this study can mutually confirm and complement each other, enhancing the capability to identify geohazards and their associated hazard cascades in densely vegetated alpine gorges, thereby providing valuable references for government departments in disaster prevention and reduction work.

Advancing treatment strategies for posterior malleolar malunion: The ankle dislocation method.

BACKGROUND: This study aimed to assess the radiological and clinical outcomes of treatment using the ankle dislocation method for posterior malleolar malunion. METHOD: Thirty-one patients with posterior malleolar malunion who underwent treatment using the ankle dislocation method from May 2015 to October 2021 were retrospectively analyzed. Key outcome measures were radiographic parameters (articular step-off, tibiofibular clear space, fibular length, tibial lateral surface angle, and ankle osteoarthritis), clinical scores (American Orthopaedic Foot and Ankle Society ankle-hindfoot scale and Visual Analogue Scale), and patient satisfaction rate. RESULT: Preoperative computed tomography revealed that Bartoní cek types 3 and 4 accounted for 64.5 % (n = 20) of total cases. Most posterior malleolar malunions were accompanied by depressed intercalary fragments (61.2 % [n = 19]). At the final follow-up, radiographic parameters and clinical scores showed significant improvements postoperatively (P < 0.05), with a high patient satisfaction rate of 77.4 %. Subgroup analysis revealed that the posterior malleolar fracture morphology significantly affected postoperative pain, particularly in more complex fractures (P < 0.001). CONCLUSION: The ankle dislocation method effectively exposes the distal tibial articular surface and facilitates the anatomical restoration of joint congruity under direct vision. This approach substantially improves the clinical and imaging outcomes in patients with complex posterior malleolar malunion. LEVELS OF EVIDENCE: Level IV, retrospective case series.

A novel distractor-assisted reduction combined with the sinus tarsi approach for joint depression-type calcaneal fractures.

PURPOSE: A novel percutaneous distractor with the advantage of axial and direct distraction was designed for the minimally invasive treatment of calcaneal fractures. The purpose of this study was to investigate the clinical results and complications of a novel distractor combined with sinus tarsi approach (STA) in treatment of the joint depression-type of calcaneal fractures. METHODS: Fifty-four patients with the depression-type of calcaneal fractures (30 Sanders type II, 22 Sanders type III, 2 Sanders type IV) who were subjected to the novel distractor combined with STA were retrospectively assessed. Calcaneal height, width, and length; Bohler's angle; and the Gissane angle were evaluated pre-operatively and post-operatively. Clinical outcomes were assessed using the American Orthopedic Foot and Ankle Society (AOFAS) and visual analog scale (VAS) pain scores from the last follow-up. Complications were also recorded. RESULTS: Fifty-two patients achieved an average follow-up of 24.3 months (range 18 to 34 months), and two patients were lost to follow-up six months post-operatively. There was significant difference between pre-operative and post-operative calcaneal height, width, and length; Bohler's angle; and Gissane angle (p < 0.01), but no significant difference was detected between the post-operative and normal side Bohler's angle (p > 0.05). The AOFAS ankle and hind foot score was 88.4 ± 6.6, and the VAS score was 1.9 ± 0.7 at the last follow-up. Nine (17.3%) patients developed complications: One experienced skin necrosis and two had screws loosening; three patients developed early degenerative changes of the subtalar joint; two had no symptoms; one had light pain around the subtalar joint without medical treatment; complex regional pain syndrome (CRPS) developed in one patient after seven months post-operatively; and two developed transient ankle stiffness. CONCLUSION: The novel distractor combined with the STA effectively reconstructs the facet depression-type of calcaneal fractures (sanders type II and III) with minimal complications.

Detecting geothermal anomalies using Landsat 8 thermal infrared remote sensing data in the Ruili Basin, Southwest China.

With the recent increase in global focus on green energy, the application of thermal infrared remote sensing data for the detection of geothermal anomalies has attracted wide attention as it can overcome the difficulty of using only ground surveying. This study aimed to highlight areas of geothermal anomalies with land surface temperature (LST) time series data in winter derived from thermal infrared remote sensing. To extract LST anomaly areas in the Ruili Basin for geothermal prospecting, nine types of data on the study area in winter during 2014 ~ 2021 from Landsat 8 were analyzed. Landsat 8 LST inversion data based on the mono-window algorithm (MWA) can be used to identify hot springs, volcanoes, and other heat-related phenomena. Superimposing LST anomalies for each cycle through drilling data, excluding the heat island effect, geothermal anomaly regions could be plotted. The results show that the accuracy of MWA LST varied within 2 K, which is acceptable for geothermal energy and higher than those of the radiative transfer equation (RTE) algorithm and MODIS LST products. Three high-LST regions in the southeast of the study area were identified as geothermal anomaly areas (A, B, and C), and region B was further verified through a comprehensive field investigation of geothermal wells, supplemented by the temperature gradient (TG) method. The findings reveal that the distribution of geothermal anomaly areas and high-LST areas are highly consistent with the northeast trending fault structure; faults act as thermal channels and help in accurately detecting local LST anomalies. Overall, the infrared remote sensing method proved to be a valid technique for detecting LST anomalies. Considering the synergy between thermal infrared surface detection and subsurface exploration methods, the identification of known geothermal fields (B) and other possible areas (A and C) has significance in the upscaling of local geologic information to regional prospecting, thus providing a direction for future geothermal research.

Identification of geothermal potential based on land surface temperature derived from remotely sensed data.

With the continuous development of thermal infrared remote sensing technology and the maturation of remote sensing inversion algorithms based on surface temperatures, identifying high-temperature anomalous areas by inverting surface temperatures has become an crucial approach to finding geothermal potential areas. The eastern region of Longyang in western Yunnan Province is renowned for geothermal resources, though the distribution area of geothermal potential remains unknown. Therefore, this study used Landsat-8 TIRS data and four surface temperature inversion algorithms, namely, mono-window algorithm, single-channel algorithm, Du split window algorithm (SWD), and Jiménez-Muñoz split window algorithm (SWJ), to explore the astern region of Longyang. The inversion results were compared with Moderate Resolution Imaging Spectroradiometer Land Surface Temperature (MODIS LST) results for analysis and cross-validation to select the optimal algorithm. A multi-view remote sensing temperature anomaly information extraction method was adopted. Moreover, the overall threshold method, the fracture structure buffer method, and the joint analysis of diurnal temporal data were combined for the reduction of the thermal anomaly area as well as for comprehensively defining the geothermal prospective area in the study area. The results demonstrated that the mono-window algorithm had the highest accuracy with a Pearson coefficient of 0.77, which is more suitable for the surface temperature inversion in Longyang area. Furthermore, three geothermal anomalies (A, B, and C) were identified in the study area, with larger thermal anomaly in A and C, but a smaller one in B. All three areas had hot spring points verified, with A and C exhibiting more significant development potential. The research results provide a reliable methodological basis for the development of geothermal resources in the region.

Energy transfer processes and structure of carboxymethyl cellulose-Tb/Eu nanocomplexes with color-tunable photoluminescence.

A series of fluorescent nanocomplexes of carboxymethyl cellulose (CMC)/Terbium (Tb)- Europium (Eu) were successfully synthesized without introducing a second ligand. By adjusting the concentration of the coordinated ions, these nanocomplexes exhibit favorably visibly tunable luminescence properties with colors being able to change from green to red. The XPS analysis demonstrates the formation Tb(III)-O2- and Eu(III)-O2- between OH and COO- in CMC and Tb3+ or Eu3+ ions, which is advantage for light absorption by UV-Vis spectroscopy and fluorescence spectroscopy. The ligand CMC plays a role in coordinating with terbium and europium ions, but also serves as an energy donor to these metal ions by antenna effect. Moreover, the energy transfer also occurred from terbium ions to europium ions in CMC matrix, which is responsible for the tunable luminescence properties of these complexes.