Controlling Droplet Marangoni Flows to Improve Microscopy-Based TB Diagnosis

In developing countries, the most common diagnostic method for tuberculosis (TB) is microscopic examination sputum smears. Current assessment requires time-intensive inspection across the microscope slide area, and this contributes to its poor diagnostic sensitivity of ≈50%. Spatially concentrating TB bacteria in a smaller area is one potential approach to improve visual detection and potentially increase sensitivity. We hypothesized that a combination of magnetic concentration and induced droplet Marangoni flow would spatially concentrate Mycobacterium tuberculosis on the slide surface by preferential deposition of beads and TB–bead complexes in the center of an evaporating droplet. To this end, slide substrate and droplet solvent thermal conductivities and solvent surface tension, variables known to impact microfluidic flow patterns in evaporating droplets, were varied to select the most appropriate slide surface coating. Optimization in a model system used goniometry, optical coherence tomography, and microscope images of the final deposition pattern to observe the droplet flows and maximize central deposition of 1 μm fluorescent polystyrene particles and 200 nm nanoparticles (NPs) in 2 μL droplets. Rain-X® polysiloxane glass coating was identified as the best substrate material, with a PBS-Tween droplet solvent. The use of smaller, 200 nm magnetic NPs instead of larger 1 μm beads allowed for bright field imaging of bacteria. Using these optimized components, we compared standard smear methods to the Marangoni-based spatial concentration system, which was paired with magnetic enrichment using iron oxide NPs, isolating M. bovis BCG (BCG) from samples containing 0 and 103 to 106 bacilli/mL. Compared to standard smear preparation, paired analysis demonstrated a combined volumetric and spatial sample enrichment of 100-fold. With further refinement, this magnetic/Marangoni flow concentration approach is expected to improve whole-pathogen microscopy-based diagnosis of TB and other infectious diseases.

The Application of Ethyl A-Cyanoacrylate in the Early Stage of Geological Experiment

In recent years, the oil field chemical A-cyanoacrylate mixed adhesive has been used in rock preparation and preparation to a certain extent, and its role has been paid more and more attention due to the solidification of the rock surface in the rock thin section, the early embedding of the rock, and the adhesion of the thin side of the rock to the slide surface, etc. This paper introduces the preparation and application development of a-cyanoacrylate mixed adhesive in geological experiment, and the development of a-cyanoacrylate mixed adhesive in oilfield geological experiment.

A model for interpreting the deformation mechanism of reservoir landslides in the Three Gorges Reservoir area, China

Landslides whose slide surface is gentle near the toe and relatively steep in the middle and rear part are common in the Three Gorges Reservoir area, China. The mass that overlies the steep part of the slide surface is termed the “driving section”, and that which overlies the gentle part of the slide surface is termed the “resisting section”. A driving–resisting model is presented to elucidate the deformation mechanism of reservoir landslides of this type, as exemplified by Shuping landslide. More than 13 years of field observations that include rainfall, reservoir level, and deformation show that the displacement velocity of Shuping landslide depends strongly on the reservoir level but only slightly on rainfall. Seepage modeling shows that the landslide was destabilized shortly after the reservoir was first impounded to 135 m, which initiated a period of steady deformation from 2003 to 2006 that was driven by buoyancy forces on the resisting section. Cyclical water level fluctuations in subsequent years also affected slope stability, with annual “jumps” in displacement coinciding with drawdown periods that produce outward seepage forces. In contrast, the inward seepage force that results from rising reservoir levels stabilizes the slope, as indicated by decreased displacement velocity. Corrective transfer of earth mass from the driving section to the resisting section successfully reduced the deformation of Shuping landslide and is a feasible treatment for huge reservoir landslides in similar geological settings.

Experimental Study on Lining Cracking of Shallow Buried Loess Tunnel under the Simulation of Effect of Slide Surface Immersion

The water immersion of surrounding rock slide surface causes lining cracking of the shallow buried loess tunnel, and different types of slide surface and different immersion degrees have different effects on secondary lining. In this paper, four types of slide surfaces for shallow buried loess tunnel are proposed. In order to find out the characteristics and laws of lining cracking under the effect of slide surface immersion, a loading model test with a large geometric similarity ratio of 1:10 was carried out. The test results show that the immersion of the slide surface has the most significant influence on the deformation of the lining vault and the arch waist, and the value and speed of the vault deformation are always the largest. When the unilateral slide surface is immersed in water, the lining cracking is concentrated on the flooded side of the slide surface, and the appearance of compressive cracks can be regarded as a precursor of lining instability. In the direction of lining thickness, the cracks always begin to develop from I-type, then gradually develop into L-type, and finally develop to Y-type, among which the number of L-type cracks is the most. Furthermore, the residual bearing capacity of cracked lining is also discussed.

A model for interpreting the deformation mechanism of reservoir landslides in the Three Gorges Reservoir area, China

Landslides whose slide surface is gentle near the toe and relatively steep in the middle and rear part are common in the Three Gorges Reservoir area, China. The mass that overlies the steep part of the slide surface is termed the driving section and that which overlies the gentle part of the slide surface is termed the locking section. A driving-locking model is presented to elucidate the deformation mechanism of reservoir landslides of this type, as exemplified by Shuping landslide. More than 13 years of field observations that include rainfall, reservoir level and deformation show that the deformation velocity of Shuping landslide depends strongly on the reservoir level but only slightly on rainfall. Seepage modelling shows that the landslide was destabilized shortly after the reservoir was first impounded to 135 m, which initiated a period of steady deformation from 2003 to 2006 that was driven by buoyancy forces on the locking section. Cyclical water-level fluctuations in subsequent years also affected slope stability, with annual jumps in displacement coinciding with drawdown periods that produce outward seepage forces. In contrast, the inward seepage force that results from rising reservoir levels stabilizes the slope, as indicated by decreased deformation velocity. Corrective transfer of earth mass from the driving section to the locking section successfully reduced the deformation of Shuping landslide, and is a feasible treatment for huge reservoir landslides in similar geological settings.

An improved method of Newmark analysis for mapping hazards of coseismic landslides

Coseismic landslides have been responsible for destroyed buildings and structures, dislocated roads and bridges, cut off of pipelines and lifelines, and tens of thousands of deaths. Accurately mapping the hazards of coseismic landslides is an important and challenge work. Newmark's method is widely applied to assess the permanent displacement along a potential slide surface to determine the coseismic responses of the slope. This paper considers the roughness and size effect of the potential slide surface-unloading joint, and then presents an improved method of Newmark analysis for mapping hazard of coseismic landslides. The improved method is verified using data from a case study of the 2014 Mw 6.1 (USGS) Ludian earthquake in Yunnan Province, China. The permanent displacement yielded from this method range from 0 to 122 cm. Comparisons are made between the predicted displacements and a comprehensive inventory of landslides triggered by the Ludian earthquake to map the spatial variability using certainty factor model (CFM). Confidence levels of coseismic landslides indicated by certainty factors range from −1 to 0.95. A coseismic landslide hazard map is then produced based on the spatial distribution of the values of certainty factors. Area under the curve analysis is used to draw a comparison between the improved and conventional method of Newmark analysis, revealing the improved performance of the method presented in this paper. Such method can be applied to predict the hazard zone of the region and provide guidelines for making decisions regarding infrastructure development and post-earthquake reconstruction.

Optimation of Least Squares Methods Smooth Constrain Using Occam’s Inversion Geoelectric Resistivity Dipole-Dipole Consfiguration for Estimation Slip Surface

The volumes of the landslide depend on the depth of the slide surface. The depth of the slide surface can be predicted by using the least squares inversion methods of data geoelectrical. Method of Least Squares Inversion of the data Geoelectrical cannot get smooth results. Based on the above, the aims was optimalitation leastsquares smooth constrain inversion methods with Occam’s inversion for geoelectrical data and to determine the depth and tilt angle of the slide surface in in Bukit Lantiak Padang . This exploratory study was use the method Geoelectrical resistivity Dipole-Dipole configuration. The depth and tilt angle of the slide surface in Bukit Lantiak Padang was interpretated by combined Occam’s inversion with least-squares smooth constrain inversion methods. The type of slip surface is translation slip with 33.45 degrees in tilt angle and 19.3 meters in depth. Research show that the result interpretation by used combined Occam inversion with least-squares smooth constrain inversion methods more sharpness than least-squares smooth constrain inversion.

Optimize of Least-Square Inverse Constrain Method of Geoelectrical Resistivity Wenner-Schlumberger for Investigation Rock Structures in Malalak Districts of Agam West Sumatra

Numerous studies have been conducted on an inversion method, focus on constraining factor,singuler value, speed of convergence. However, the result of inversion is not unique and bivalent. In this research, we optimize of Least-Square constrain by using damping factor. Th is method used for interpretation of the volumes and rock structure in Malalak Distric of Agam West Sumatra. This is undertaken because Malalak districts of Agam West Sumatra that passed by highway Padang and Bukittingi is a frequent area of landslide. Furthermore, the frequency of the landslide depends on the type of rock and the angle of the slope . The depth of the slide surface can be predicted by using the least squares inversion constrain method of Geoelectric Resistivity. Landslides resulted in disruption of transportation between the city of Padang and another district in Sumatra. Based on the above, to determine the rock's structure, the depth and tilt angle of the slide surface in Malalak districts Agam West Sumatra has to take place. Data obtained through Geoelectrical exploration using with automatic resistivitymeter equipment. Constrains were obtained using the Marquat inversion method. The result of the research is first, the damping factor for structures which have wide range resistivity is 0.02 and the smallest damping factor is 0.015. Second, the rock structure in Malalak of Agam consists of clay, sandstone, andesite, and limestone and dolomite. Implementation this research can be used to develop mitigation of landslide deserter.

OPTIMITION OF LEAST SQUARES METHODS SMOOTH CONSTRAIN USING OCCAM’S INVERSION GEOELECTRIC RESISTIVITY DIPOLE-DIPOLE CONFIGURATION FOR ESTIMATION SLIP SURFACE

The volumes of the landslide depend on the depth of the slide surface. The depth of the slide surface can bepredicted by using the least squares inversion methods of data geoelectrical. Method of Least Squares Inversionof the data Geoelectrical cannot get smooth results. Based on the above, the aims was optimalitation leastsquaressmooth constrain inversion methods with Occam’s inversion for geoelectrical data and to determine thedepth and tilt angle of the slide surface in in Bukit Lantiak Padang . This exploratory study was use the methodGeoelectrical resistivity Dipole-Dipole configuration. The depth and tilt angle of the slide surface in BukitLantiak Padang was interpretated by combined Occam’s inversion with least-squares smooth constraininversion methods. The type of slip surface is translation slip with 33.450 tilt angle and 19.3 meters in depth.Research show that the result interpretation by used combined Occam inversion with least-squares smoothconstrain inversion methods more sharpness than least-squares smooth constrain inversion.