Exploring the geological factors that affect fluid flow has always been a hot topic. For tight reservoirs, the pore structure and characteristics of different lithofacies reveal the storage status of ...fluids in different reservoir environments. The size, connectivity, and distribution of fillers in different sedimentary environments have always posed a challenge in studying the microscopic heterogeneity. In this paper, six logging curves (gamma-ray, density, acoustic, compensated neutron, shallow resistivity, and deep resistivity) in two marker wells, namely, J1 and J2, of the Permian Lucaogou Formation in the Jimsar Basin are tested by using four reinforcement learning algorithms: LogitBoost, GBM, XGBoost, and KNN. The total percent correct of training well J2 is 96%, 96%, 96%, and 96%, and the total percent correct of validation well J1 is 75%, 68%, 72%, and 75%, respectively. Based on the lithofacies classification obtained by using reinforcement learning algorithm, micropores, mesopores, and macropores are comprehensively described by high-pressure mercury injection and low-pressure nitrogen gas adsorption tests. The multifractal theory servers for the quantitative characterization of the pore distribution heterogeneity regarding different lithofacies samples, and as observed, the higher probability measure area of the generalized fractal spectrum affects the heterogeneity of the local interval of mesopores and macropores of the estuary dam. In the micropore and mesopore, the heterogeneity of the evaporation lake showed a large variation due to the influence of the higher probability measure area, and in the mesopore and macropore, the heterogeneity of the evaporation lake was controlled by the lower probability measure area. According to the correlation analysis, the single-fractal dimension is well related to the multifractal parameters, and the individual fitting degree reaches up to 99%, which can serve for characterizing the pore size distribution uniformity. The combination of boosting machine learning and multifractal can help to better characterize the micro-heterogeneity under different sedimentary environments and different pore size distribution ranges, which is helpful in the exploration and development of oil fields.
The beach-bar reservoir has become an important exploration target in China, but its depositional mechanism and controlling factors have not yet been fully modeled. They have become an inhibitory ...factor for the exploration and development of beach-bar reservoirs. The depositional mechanism of beach-bars and their controlling factors have been studied by means of a flume experiment including seven runs under controlled boundary conditions which were the water level (Run 1, Run 2 and Run 3), wave parameters (Run 1, Run 4 and Run 5) and initial slope (Run 1, Run 6 and Run 7). The experiment revealed that the development of beach-bar was controlled by water level, wave parameters and initial slope. The deposited locations of distal bar and nearshore bar were controlled by the water level. Two beach-bars were migrated downward when the water level falls (Run 1, Run 2 and Run 3). The width and thickness of distal bar and nearshore bar were controlled by wave parameters, especially the wave height. They increased with the scale of wave. But, the maximum thickness is limited by the water level (Run 1, Run 4 and Run 5). The distance between distal bar and nearshore bar was controlled by the initial slope. It became shorter with the steeper slope. Distal bar and nearshore bar changed into one bar when the initial gradient was greater than 1/20 (Run 1, Run 6 and Run 7). The results suggest formative mechanism and controlling factors related to beach-bars.
Grain size analysis is a common method in the study of sedimentology. For the consolidated sedimentary rocks, the traditional methods are rock slice observation and image analysis. In recent years, ...laser particle size analyzer is used widely in particle size analysis of sedimentary rock. Unlike the pretreatment of loose samples, the rock samples must be crushed, added acid to wipe out cement, and washed. However, in the step of washing, most of the fines component (less than 63 μm) in the suspended state should be inevitably lost. It will significantly affect the accuracy of particle size analysis, especially for siltstone. This paper presents a siltstone sample pretreatment method which core step is washing acid by centrifuge. Compared with traditional decantation method, the results show that the median particle size reduced 33.2 μm on average. Compared with the precipitation method which is commonly used for handling loose samples, the change of solid-liquid separation time is from 12 h to 10 min, while the average reduction of median particle size is about 15 μm. The grain size value corresponded to the cumulative volume of 10%/90% reduced 2.5 μm/20.3 μm on average. The percentage of the clay component less than 2 μm increased 2.88% on average. The fine particle (2–4 μm) and silt component (4–63 μm) increased 1.71% and 5.56% on average. Based on this method, two kinds of similar lacustrine siltstone were analyzed. They are tempestite and beach bar which are difficult to identify in the Lijin sub-depression, Dongying depression, Shengli oilfield, China. The final grain-size probability plot of tempestite is the type of “one saltation component and three suspension components”. The content of suspension components can reach to 80%–90%. The beach bar is the type of “one saltation component and two suspension components”. The content of suspension components can reach to 40%–45%. They both have the characteristics of high slope which means well sorting. But they can be distinguished based on the suspension sedimentary characteristics which were preserved by maximum degree in this kind of sample pretreatment method.
Here, we report two paired sets of an index wild-type Candida glabrata bloodstream isolate and subsequent echinocandin-resistant FKS mutant. One paired set exhibited a higher proportion of clumping ...cells and was more virulent in the invertebrate host Galleria mellonella than the other paired set. No virulence difference between the paired index and FKS strains was observed. These findings imply a potential link of clumping morphology with virulence in C. glabrata that is uncoupled from FKS-mediated echinocandin resistance.
Candida glabrata is a leading cause of invasive candidiasis. In contrast to other species, it has a high propensity for developing resistance to echinocandins, which are the first-line treatment. Unlike the dimorphic Candida albicans which can grow invasive filamentous hyphae, C. glabrata lacks this ability. Here, we report a link between virulence and clumping cell morphology in two different sets of clinical C. glabrata strains obtained from patients failing echinocandin therapy. One set of paired strains (echinocandin-susceptible and subsequent resistant mutant) had a high proportion of clumping cells in the population and were significantly more virulent than another set which had fewer clumping cells. Additionally, we corroborate that echinocandin resistance does not impart a significant fitness cost. Our findings suggest that clumping morphology may be an important but previously underestimated virulence factor for C. glabrata and also aid our understand for the high prevalence of resistance observed in this species.
An indirect inhibitive surface plasmon resonance (SPR) immunoassay was developed for the microcystins (MCs) detection. The bioconjugate of MC-LR and bovine serum albumin (BSA) was immobilized on a ...CM5 sensor chip. A serial premixture of MC-LR standards (or samples) and monoclonal antibody (mAb) were injected over the functional sensor surface, and the subsequent specific immunoreaction was monitored on the BIAcore 3000 biosensor and generated a signal with an increasing intensity in response to the decreasing MCs concentration. The developed SPR immunoassay has a wide quantitative range in 1–100
μg
L
−1. Although not as sensitive as conventional enzyme-linked immunosorbent assay (ELISA), the SPR biosensor offered unique advantages: (1) the sensor chip could be reusable without any significant loss in its binding activity after 50 assay-regeneration cycles, (2) one single assay could be accomplished in 50
min (including 30-min preincubation and 20-min BIAcore analysis), and (3) this method did not require multiple steps. The SPR biosensor was also used to detect MCs in environmental samples, and the results compared well with those obtained by ELISA. We conclude that the SPR biosensor offers outstanding advantages for the MCs detection and may be further developed as a field-portable sensor for real-time monitoring of MCs on site in the near future.
•Evolution of mcy genes resulted in coexistence of toxic and nontoxic cyanobacteria.•Microcystins (MCs) serve multiple biological functions in cyanobacteria.•MCs enhance plasticity of toxic ...cyanobacteria to changing environments.•Intracellular MCs function in carbon/nitrogen metabolism and antioxidation.•Extracellular MCs function in cell-to-cell communication and colony formation.
Microcystins are potent hepatotoxins predominantly produced by bloom-forming freshwater cyanobacteria (e.g., Microcystis, Planktothrix, Dolichospermum). Microcystin biosynthesis involves large multienzyme complexes and tailoring enzymes encoded by the mcy gene cluster. Mutation, recombination, and deletion events have shaped the mcy gene cluster in the course of evolution, resulting in a large diversity of microcystin congeners and the natural coexistence of toxic and non-toxic strains. The biological functions of microcystins and their association with algal bloom formation have been extensively investigated over the past decades. This review synthesizes recent advances in decoding the biological role of microcystins in carbon/nitrogen metabolism, antioxidation, colony formation, and cell-to-cell communication. Microcystins appear to adopt multifunctional roles in cyanobacteria that reflect the adaptive plasticity of toxic cyanobacteria to changing environments.
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Purpose of Review
The global emergence of antifungal resistance among
Candida
spp. and
Aspergillus
spp. is a growing threat to public health, driven largely by the expanding use of antifungals in ...both the clinical and agricultural settings. As treatment options remain limited, understanding mechanisms and risk factors for antifungal resistance is essential to retaining their clinical utility.
Recent Findings
Invasive candidiasis is increasingly caused by non-
albicans Candida
species with reduced susceptibility to first-line antifungals, making empiric treatment decisions difficult. Echinocandin resistance in
C. glabrata
is increasing at some high-risk centers, and multi-drug-resistant isolates are increasingly encountered. Of large concern is the rapid and global emergence of
C. auris
, a species associated with a high propensity for developing multi-drug resistance and nosocomial transmission. Azole resistance is now becoming more common in
Aspergillus
isolates as well, with breakthrough infections occurring in patients previously managed with azoles antifungals. The appearance of azole-resistant
Aspergillus
isolates in azole-naïve patients is also concerning, given it is now accepted that this may be due to the use of non-human azole compounds in pesticides.
Summary
Due to the climbing use of antifungals in both the clinical and agricultural sectors, the frequency of encounters with antifungal-resistant isolates will undoubtedly rise in parallel. Antifungal stewardship will need to become a new priority for antimicrobial stewardship programs in order to preserve our current selection of antifungal agents. Rapid diagnostics may help stewardship efforts by decreasing the time it takes to determine if an antifungal agent is indicated for a patient.
Microscopic technologies including light and fluorescent, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cryo-electron microscopy have been widely utilized to ...visualize Clostridioides difficile at the molecular, cellular, community, and structural biology level. This comprehensive review summarizes the microscopy tools (fluorescent and reporter system) in their use to study different aspects of C. difficile life cycle and virulence (sporulation, germination) or applications (detection of C. difficile or use of antimicrobials). With these developing techniques, microscopy tools will be able to find broader applications and address more challenging questions to study C. difficile and C. difficile infection.
•Microscopic technologies are widely used to visualize Clostridioides difficile.•Microscopic techniques are used at the molecular, cellular, and community level.•This comprehensive review summarizes these microscopic tools to study C. difficile.
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