Weak Heterogeneity Research Articles

Analysis of Spatial Heterogeneity and the Scale of the Impact of Changes in PM2.5 Concentrations in Major Chinese Cities between 2005 and 2015

Deteriorating air quality is one of the most important environmental factors posing significant health risks to urban dwellers. Therefore, an exploration of the factors influencing air pollution and the formulation of targeted policies to address this issue are critically needed. Although many studies have used semi-parametric geographically weighted regression and geographically weighted regression to study the spatial heterogeneity characteristics of influencing factors of PM2.5 concentration change, due to the fixed bandwidth of these methods and other reasons, those studies still lack the ability to describe and explain cross-scale dynamics. The multi-scale geographically weighted regression (MGWR) method allows different variables to have different bandwidths, which can produce more realistic and useful spatial process models. By applying the MGWR method, this study investigated the spatial heterogeneity and spatial scales of impact of factors influencing PM2.5 concentrations in major Chinese cities during the period 2005–2015. This study showed the following: (1) Factors influencing changes in PM2.5 concentrations, such as technology, foreign investment levels, wind speed, precipitation, and Normalized Difference Vegetation Index (NDVI), evidenced significant spatial heterogeneity. Of these factors, precipitation, NDVI, and wind speed had small-scale regional effects, whose bandwidth ratios are all less than 20%, while foreign investment levels and technologies had medium-scale regional effects, whose bandwidth levels are 23% and 32%, respectively. Population, urbanization rates, and industrial structure demonstrated weak spatial heterogeneity, and the scale of their influence was predominantly global. (2) Overall, the change of NDVI was the most influential factor, which can explain 15.3% of the PM2.5 concentration change. Therefore, an enhanced protection of urban surface vegetation would be of universal significance. In some typical areas, dominant factors influencing pollution were evidently heterogeneous. Change in wind speed is a major factor that can explain 51.6% of the change in PM2.5 concentration in cities in the Central Plains, and change in foreign investment levels is the dominant influencing factor in cities in the Yunnan-Guizhou Plateau and the Sichuan Basin, explaining 30.6% and 44.2% of the PM2.5 concentration change, respectively. In cities located within the lower reaches of the Yangtze River, NDVI is a key factor, reducing PM2.5 concentrations by 9.7%. Those results can facilitate the development of region-specific measures and tailored urban policies to reduce PM2.5 pollution levels in different regions such as Northeast China and the Sichuan Basin.

A comparison of two deep-learning-based urban perception models: which one is better?

Urban perception is a hot topic in current urban study and plays a positive role in urban planning and design. At present, there are two methods to calculate urban perception. 1) Using a model to learn image features directly automatically; 2) Coupling machine learning and feature extraction based on expert knowledge (e.g. object proportion) method. With two typical streets in Wuhan as the study area, video data were recorded and used as the model input. In this study, two representative methods are selected: 1) End to end convolution neural network (CNN-based model); 2) Based on full convolution neural network and random forest (FCN + RF-based model). By comparing the accuracy of two models, we analyze the adaptability of the model in different urban scenes. We also analyze the relationship between CNN-based model and urban function based on POI data and OSM data, and verify its interpretability. The results show that the CNN-based model is more accurate than FCN + RF-based model. Because the CNN-based model considers the topological characteristics of the ground objects, its perception results have a stronger nonlinear correlation with urban functions. In addition, we also find that the CNN-based model is more suitable for scenes with weak spatial heterogeneity (such as small and medium-sized urban environments), while the FCN + RF-based model is applicable to scenes with strong spatial heterogeneity (such as the downtown areas of China’s megacities). The results of this study can be used as a reference to provide decision support for urban perception model selection in urban planning.

Large-Scale Acid Fracturing Based on a Large-Scale Conductivity Apparatus.

The conductivity of an acid-etched fracture is a necessary indicator for the stimulation of dolomite formation, which affects commercial development. The widely accepted test method involves the use of a small-scale conductivity cell for etching and measuring conductivity. However, the field production reflects that the actual conductivity does not match the measured one and is usually lower. Consequently, the existing studies had limitations and hence the stimulation mechanism needed to be explored further. To understand it more realistically, a novel large-scale apparatus was used in this study to test the conductivity of the acid-etched fracture. The use of this apparatus avoided the near-core excessive eroding and weak heterogeneity with continuous etching in a 1000 mm fracture. The results showed that the conductivity was indeed dissimilar to that in small-scale tests. The morphology of etched large-scale cores featured diversity and complexity, including deep and punctate channels, nonuniform pitting grooves with connected channels, and scale-shaped wavy grooves, which exactly demonstrated the multiple morphology under the influence of carbonate heterogeneity in real reservoirs. Moreover, the effect of increasing injection rate led to the unique etching morphology of scale-shaped wavy and pelviform grooves because of scouring flow and turbulence effects. The degree of surface roughness promoted nonuniform etching along the longitudinal and propagation direction, thus enhancing the conductivity of the whole fracture and confirming that the field treatment limited the pressure rather than the injection rate. The conductivity under different acid type, acid concentration, reaction temperature, and injection rate conditions was lower than that reported, confirming the experimental deviation in small-scale conductivity. The proposed large-scale apparatus test represented the acid-etched fracture conductivity more realistically, thus proving beneficial for the development of carbonate reservoirs.

Tocilizumab in COVID-19 interstitial pneumonia.

BackgroundPublished reports on tocilizumab in COVID‐19 pneumonitis show conflicting results due to weak designs or heterogeneity in critical methodological issues.MethodsThis open‐label trial, structured according to Simon's optimal design, aims to identify factors predicting which patients could benefit from anti‐IL6 strategies and to enhance the design of unequivocal and reliable future randomized trials. A total of 46 patients with COVID‐19 pneumonia needing of oxygen therapy to maintain SO2 > 93% and with recent worsening of lung function received a single infusion of tocilizumab. Clinical and biological markers were measured to test their predictive values. Primary end point was early and sustained clinical response.ResultsTwenty‐one patients fulfilled pre‐defined response criteria. Lower levels of IL‐6 at 24 h after tocilizumab infusion (P = 0.049) and higher baseline values of PaO2/FiO2 (P = 0.008) predicted a favourable response.ConclusionsObjective clinical response rate overcame the pre‐defined threshold of 30%. Efficacy of tocilizumab to improve respiratory function in patients selected according to our inclusion criteria warrants investigations in randomized trials.

Pore Size Distribution and Fractal Characteristics of the Nanopore Structure in Organic-Rich Shales Using the Neimark-Kiselev Fractal Approach.

Shale gas has been playing an increasingly important role in meeting global energy demands. The heterogeneity of the pore structure in organic-rich shales greatly affects the adsorption, desorption, diffusion and flow of gas. The pore size distribution (PSD) is a key parameter of the heterogeneity of the shale pore structure. In this study, the Neimark-Kiselev (N-K) fractal approach was applied to investigate the heterogeneity in the PSD of the lower Silurian organic-rich shales in South China using low-pressure N₂ adsorption, total organic carbon (TOC) content, maturity analysis, X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) measurements. The results show that (1) the fractal dimension DN-K obtained by N-K theory better represents the heterogeneity of the PSD in shale at an approximately 1-100 nm scale. The DN-K values range from 2.3801 to 2.9915, with a mean of 2.753. The stronger the PSD heterogeneity is, the higher the DN-K value in shale is. (2) The clay-rich samples display multimodal patterns at pore sizes greater than 20 nm, which strongly effect the PSD heterogeneity. Quartz-rich samples display major peaks at less than or equal to a 10 nm pore size, with a smaller effect on the PSD heterogeneity in most cases. In other brittle mineral-rich samples, there are no obvious major peaks, and a weak heterogeneity of the PSDs is displayed. (3) A greater TOC content, maturity, clay content and pore size can cause stronger heterogeneity of the PSD and higher fractal dimensions in the shale samples. This study helps to understand and compare the PSD and fractal characteristics from different samples and provides important theoretical guidance and a scientific basis for the exploration and development of shale gas resources.

Exploring the Relationship Between Psychiatric Traits and the Risk of Mouth Ulcers Using Bi-Directional Mendelian Randomization

BackgroundAlthough the association between mouth ulcers and psychiatric traits has been reported by observational studies, their causal relationship remains unclear. Mendelian randomization (MR), powered by large-scale genome-wide association studies (GWAS), provides an opportunity to clarify the causality between mouth ulcers and psychiatric traits.MethodsWe collected summary statistics of mouth ulcers (sample size n = 461,106) and 10 psychiatric traits from the largest publicly available GWAS on Europeans, including anxiety disorder (n = 83,566), attention deficit/hyperactivity disorder (n = 53,293), autism spectrum disorder (n = 46,350), bipolar disorder (n = 51,710), insomnia (n = 1,331,010), major depressive disorder (n = 480,359), mood instability (n = 363,705), neuroticism (n = 168,105), schizophrenia (n = 105,318), and subjective wellbeing (n = 388,538). We applied three two-sample bi-directional MR analysis methods, namely the Inverse Variance Weighted (IVW) method, the MR pleiotropy residual sum and outlier (MR-PRESSO) method, and the weighted median method, to assess the causal relationship between each psychiatric trait and mouth ulcers.ResultsWe found significant effects of autism spectrum disorder, insomnia, major depressive disorder, and subjective wellbeing on mouth ulcers, with the corresponding odds ratio (OR) from the IVW method being 1.160 [95% confidence interval (CI): 1.066–1.261, P = 5.39 × 10–4], 1.092 (1.062–1.122, P = 3.37 × 10–10), 1.234 (1.134–1.342, P = 1.03 × 10–6), and 0.703 (0.571–0.865, P = 8.97 × 10–4), respectively. We also observed suggestive evidence for mood instability to cause mouth ulcers [IVW, OR = 1.662 (1.059–2.609), P = 0.027]. These results were robust to weak instrument bias and heterogeneity. We found no evidence on causal effects between other psychiatric traits and mouth ulcers, in either direction.ConclusionOur findings suggest a protective effect of subjective wellbeing and risk effects of autism spectrum disorder, insomnia, major depressive disorder, and mood instability on mouth ulcers. These results clarify the causal relationship between psychiatric traits and the development of mouth ulcers.

Effect of Fine Particles and Soil Heterogeneity on the Initiation of Suffusion

Hydraulic backfill structures can be affected by internal erosion, which develops if 2 conditions are met: detachment and migration of particles due to hydraulic seepage. Suffusible soils involve an easy movement of fine particles within the matrix, and this process depends on the particle size distribution of the soil and hydraulic load. If suffusion in homogeneous soils has been widely studied, it has rarely been approached in heterogeneous soils. Cohesionless soils can involve many heterogeneities, due to gap grading or segregation, which can be a cause of internal erosion under severe seepage. In this study, attempts are made to evaluate the influence of fine particles type, rate and distribution of heterogeneity on the onset and development of suffusion. This process is investigated by using a soil sample within a column, submitted to a horizontal unidirectional flow. Different types of fines (kaolinite, illite, silt) and three configurations (central, downstream, and distributed) involving different rates are used by the introduction of coarse sand into a mixture of fine sand and fine particles. Two heterogeneity rates of 20% (weak heterogeneity) and 60% (high heterogeneity) were used and the results were matched with those obtained on the homogeneous soil. The results show that among the fine particles tested with the same configuration and heterogeneity rate, illite provides the highest resistance to suffusion. In addition, suffusion increases with the heterogeneity rate above a given threshold value. These results help us to assess a better understanding of the effect of heterogeneities on the transport and retention mechanisms of fines in granular soils.

Influence of Charge Regulation and Charge Heterogeneity on Complexation between Weak Polyelectrolytes and Weak Proteins Near Isoelectric Point

AbstractA combination of constant pH method and single chain in mean field simulations is employed to probe the influence of charge regulation and charge heterogeneities on the bridging characteristics of dissociable polyelectrolytes on globular proteins. By adopting a coarse‐grained representation of proteins as spherical particles, the influence of charge patches on the polyelectrolyte bridging probabilities near protein isoelectric points and in regimes in which the net charge of the protein is the same sign as that of the polyelectrolytes is probed. The results demonstrate that in the presence of dissociable polyelectrolytes, the probability of bridging of proteins capable of charge regulation is higher relative to proteins which are completely dissociated. For homogeneously charged proteins and/or proteins with weak charge heterogeneities, partially dissociated polyelectrolytes are seen to exhibit enhanced bridging characteristics compared to completely dissociated polyelectrolytes. In contrast, for proteins exhibiting strong charge heterogeneities, dissociable polyelectrolytes are seen to exhibit weaker bridging compared to completely dissociated polyelectrolytes.

First Identification and Characterization of Lactococcus garvieae Isolated from Rainbow Trout (Oncorhynchus mykiss) Cultured in Mexico.

Simple SummaryLactococcus garvieae is an emerging pathogen that causes lactococcosis, which is a septicemia disease that, as per reports, primarily affects rainbow trout and tilapia in various parts of the world. In rainbow trout, the clinical disease is very similar to other diseases caused by Gram-positive bacteria, including weissellosis, which has been previously reported in trout in Mexico. Following septicemia outbreaks that tested negative for weissellosis, a study was conducted to determine the etiology. This study confirms, for the first time, the presence of L. garvieae in processes of a septicemia disease affecting five rainbow trout farms in Mexico. Fourteen isolates were obtained from different geographical regions, but presented homogenous biochemical and protein profiles, as well as weak genetic heterogeneity. This study evidences the wide distribution and incidence of lactococcosis cases at rainbow trout farms in Mexico, demonstrating the need to develop vaccination programs against this disease.Lactococcosis is a hyperacute hemorrhagic septicemia disease caused by Lactococcus garvieae, which is an emerging pathogen in global fish farming. Between 2016 and 2018, rainbow trout (Oncorhynchus mykiss) from five farms that presented outbreaks were sampled as part of a Mexican surveillance program for the detection of fish diseases. Fourteen L. garvieae isolates were recovered from sampled fish, as confirmed by biochemical tests, 16S rRNA gene sequencing, and clinical and histological insights. The biochemical and protein profiles of the isolates obtained were homogeneous. Repetitive extragenic palindromic—(REP)—and enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) analyses established weak genetic heterogeneity. Rainbow trout challenged with two of the isolates used at different bacterial concentrations (10−2 and 10−4 CFU/mL) showed melanosis, and hemorrhages were observed in the fins, liver, kidney, and spleen. Isolates were obtained from all of the organs sampled, including from surviving fish, as either pure or mixed cultures. The present study is the first to confirm the presence of L. garvieae as the agent of severe lactococcosis outbreaks in the two primary Mexican states for trout farming.

Effects of rheology and mantle temperature structure on edge-driven convection: Implications for partial melting and dynamic topography

Edge-driven convection, which affects partial melting, intraplate volcanism, and dynamic topography, is small-scale convection that occurs along a lithospheric keel with a sharp contrast in lithospheric thickness. Various factors, including Rayleigh number, lateral mantle temperature heterogeneity, and geometry of the keel, influence the edge-driven convection, and the correlation between edge-driven convection and surface expressions (dynamic topography and volcanism) is complicated. We performed a finite element study to quantify the effects of these factors on dynamic topography and partial melting. We found that the dynamic topography is more prominent when a strong edge-driven convection cell develops, which corresponds to homogeneous mantle temperatures and the absence of mantle wind. In contrast, the development of edge-driven convection cells and dynamic topography near the lithospheric keel are hindered when the mantle temperature is strongly heterogeneous (laterally varying ~280 K). This indicates that a large lateral contrast in mantle temperature results in a strong mantle wind that may prevent the development of edge-driven convection cells. An increase in the Rayleigh number results in more vigorous convection and enhances partial melting. Our study shows that the location of volcanic activity at craton edges and passive margins can be reproduced in models with weakly heterogeneous mantle temperature for given mantle viscosity. The existence of a strong mantle wind (e.g., related to subducting slabs or mantle plumes) may inhibit the formation of an edge-driven convection cell and its related partial melt near a lithospheric keel. However, mantle conditions with weak temperature heterogeneity (<~14 K) or high mantle viscosity (>17×1019 Pa∙s), which corresponds to the Rayleigh number of 1.8×106, do not induce partial melts despite the development of edge-driven convection cells. Our model parametrized the condition and location of edge-driven convection cells and partial melts, which can contribute to understanding anomalous intraplate volcanisms, such as in Jeju Island south of the Korean Peninsula and the Tanzania Craton near the East African Rift.

Psychiatric Traits and Risk of Mouth Ulcers: A Two-Sample Bi-Directional Mendelian Randomization Study

Background: The association between mouth ulcers and psychiatric traits has been reported by observational studies. However, their causal relationship remains unclear. Methods: We collected summary statistics of mouth ulcers and ten psychiatric traits from the largest publicly available genome-wide association studies (GWAS) on Europeans, including anxiety disorder (sample size n=83,566), attention deficit/hyperactivity disorder (n=53,293), autism spectrum disorder (n=46,350), bipolar disorder (n=51,710), insomnia (n=1,331,010), major depressive disorder (n=480,359), mood instability (n=363,705), neuroticism (n=168,105), schizophrenia (n=105,318), and subjective well-being (n=388,538). For each psychiatric trait, we conducted two-sample bi-directional Mendelian randomization (MR) analyses to assess its causal relationship with mouth ulcers. Findings: We found strong evidence that autism spectrum disorder, insomnia, major depressive disorder, mood instability, and subjective well-being had causal effects on mouth ulcers, and the corresponding odds ratio (OR) (95% CI ) were 1.160 (95% CI : 1.066-1.261, P=5.39×10-4), 1.092 (1.062-1.122, P=3.37×10-10), 1.234 (1.134-1.342, P=1.03×10-6), 1.662 (1.059-2.609, P=0.027), and 0.703 (0.571-0.865, P=8.97×10-4), respectively. These results were robust to weak instrument bias and heterogeneity. We found no evidence on causal effects between other psychiatric traits and mouth ulcers, in either direction. Interpretation: Our findings suggest a protective effect of subjective well-being, and risk effects of autism spectrum disorder, insomnia, major depressive disorder, and mood instability on mouth ulcers. Our results clarify the causal relationship between psychiatric traits and the development of mouth ulcers. Funding Statement: This study was supported by the Natural Science Foundation of China (NSFC 81973148) and the Huazhong University of Science and Technology. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Because this study used published GWAS summary statistics available in the public domain, specific ethical review or consent from study participants was not sought.

Shell design from planar pre-stressed structures

The interplay between mechanics and geometry is used to construct a theoretical framework able to describe the class of three-dimensional objects that can be fabricated from suitable planar designs by using relaxation of pre-strains/stress in ultra-thin films. Small deformations and large rotations are used here to model the elastic relaxation into various three-dimensional shapes. Over the kinematics associated with the designed mid-surface, a small perturbation of Love–Kirchhoff type is considered in order to deduce the design plate-to-shell equations for orthotropic materials with an important pre-stress/strain heterogeneity. The resulting equations for the efforts average and efforts moments provide the supplementary equations to compute the in-plane pre-strain/stress. In particular, for materials with a weak material transversal heterogeneity the moments equations involve only the thickness, the curvature tensor, and the pre-strain/stress moments. Special attention is devoted to materials that can be obtained by layer-by-layer crystal growth (molecular beam epitaxy), which posses an in-plane isotropic pre-strain. We have found that a rectangular plate could relax both into a cylindrical surface or on a part of a sphere in which case it should have a small diameter with respect to the sphere radius. In both cases, the theoretical estimates have been compared with the experimental realizations and finite-element numerical computations and we found very good agreement among all of them. In addition, for the cone geometry we found that the design is not possible from an isotropic pre-stress with an in-plane homogeneity. However, the 3D finite-element computation of the relaxed surface with a (necessary) non-isotropic pre-stress obtained from the theoretical estimates matches remarkably well the designed conical surface.

Effects of Mesoscale Surface Heterogeneity on the Afternoon and Early Evening Transition of the Atmospheric Boundary Layer

Large-eddy simulation is used to examine the afternoon and early evening transition of the atmospheric boundary layer (ABL) over heterogeneous surfaces with respect to the decay of the turbulence kinetic energy (TKE). The heterogeneous surface sensible heat flux is prescribed based on the inverse transform of the Fourier spectrum whose slope is controlled to behave as $$ \kappa^{0} $$, $$ \kappa^{ - 1} $$, $$ \kappa^{ - 2} $$, and $$ \kappa^{ - 3} $$ (where $$ \kappa $$ is the wavenumber) in the wavelength range from 18 to 0.2 km. The $$ \kappa^{0} $$ slope spectrum corresponds to a randomly homogeneous field of surface flux, which is implicitly assumed in the grid cells of most large-scale models. The spectral slopes of negative exponents represent heterogeneous surface fields with a larger negative exponent describing stronger mesoscale heterogeneity. The results for a homogeneous surface flux are consistent with that of previous studies in which, during the transition period, the decay of the volume-averaged TKE normalized with the convective velocity scale follows the power law $$ \tau^{ - n} $$ (where $$ \tau $$ is time normalized by the eddy turnover time scale) for exponents n = 1, 2, and 6. While the $$ \tau^{ - 6} $$ portion still remains over the surface with weak mesoscale heterogeneity, the $$ \tau^{ - 6} $$ portion of the spectrum is replaced with a $$ \tau^{ - 2/3} $$ portion over moderate heterogeneity, and the $$ \tau^{ - 2} $$ and $$ \tau^{ - 6} $$ portions are replaced with $$ \tau^{ - 2/3} $$ and $$ \tau^{ - 1} $$ portions of the spectrum over strong heterogeneity, resulting from the surface-heterogeneity-induced horizontal flow persisting after sunset. In fact, mesoscale features across the ABL become more apparent with the reduced number of turbulent eddies in the evening.

Response of Convective Boundary Layer and Shallow Cumulus to Soil Moisture Heterogeneity: A Large‐Eddy Simulation Study

AbstractIn this study, the impact of varying soil moisture heterogeneity (spatial variance and structure) on the development of the convective boundary layer and shallow cumulus clouds was investigated. Applying soil moisture heterogeneity generated via spatially correlated Gaussian random fields based on a power law model and idealized atmospheric vertical profiles as initial conditions, three sets of large‐eddy simulations provide insight in the influence of soil moisture heterogeneity on the ensuing growth of the convective boundary layer and development of shallow cumulus clouds. A sensitivity on the strong, weak, and unstructured soil moisture heterogeneity is investigated. The simulation results show that domain‐averaged land surface sensible heat and latent heat flux change strongly with changing soil moisture variance because of the interactions between surface heterogeneity and induced circulations, while domain means of soil moisture are identical. Vertical profiles of boundary layer characteristics are strongly influenced by the surface energy partitioning and induced circulations, especially the profiles of liquid water and liquid water flux. The amount of liquid water and liquid water flux increases with increasing structure. In addition, the liquid water path is higher in case of strongly‐structured heterogeneity because more available energy is partitioned into latent heat and more intensive updrafts exist. Interestingly, the increase of liquid water path with increasing soil moisture variance only occurs in the strongly structured cases, which suggests that soil moisture variance and structure work conjunctively in the surface energy partitioning and the cloud formation.

Automated liver and tumor segmentation based on concave and convex points using fuzzy c-means and mean shift clustering

Identifying liver and tumour regions from medical images using fully automated computer-aided software is a challenging task for the diagnosis of liver disease. In this paper, a novel method is presented to overcome the problems of liver and tumour segmentation in CT images such as weak boundaries, touching organs, and heterogeneity of the liver. Organ edges were extracted using the Kirsch filter, and the concave and convex points were subsequently calculated. The mean-shift algorithm was employed to make the images uniform along the organ borders. Finally, the FCM approach was used to segment the liver and tumours. The results demonstrated that our complex algorithm achieved an average surface distance (ASD) of 1.1±0.39mm and volume overlap error (VOE) of 1.8±0.34% while segmenting the liver. An ASD of 1.5±0.55mm and VOE of 9.8±3.9% were obtained with respect to tumour segmentation.

Performance of composite mineral adsorbents for removing Cu, Cd, and Pb ions from polluted water

This study evaluated the efficiency of the removal of heavy metals from contaminated water via adsorption isotherm and kinetic experiments on two composite mineral adsorbents, CMA1 and CMA2. The developed CMA1 (zeolite with clinoptilolite of over 20 weight percent and feldspar of ~10 percent, with Portland cement) and CMA2 (zeolite with feldspar of over 15 weight percent and ~9 percent clinoptilolite, with Portland cement) were applied to remove Cu, Cd, and Pb ions. Based on the adsorption isotherm and kinetic experiments, the adsorbents CMA1 and CMA2 exhibited high removal efficiency for Cu, Cd, and Pb ions in solution compared to other adsorbents. In the adsorption kinetic experiment, CMA2 demonstrated better adsorption than CMA1 with the same initial concentration and reaction time, and Cu, Cd, and Pb ions almost reached equilibrium within 180 min for both CMA1 and CMA2. The results of the adsorption kinetic experiments with pseudo-first-order (PFO) and pseudo-second-order (PSO) models indicated that the PSO model was more suitable than the PFO model. Comparing the Langmuir and Freundlich adsorption isotherm models, the former showed a very slightly higher correlation coefficient (r2) than the latter, indicating that the two models can both be applied to heavy metal solutions on a spherical monolayer surface with a weak heterogeneity of the surface. Additionally, the adsorbents CMA1 and CMA2 demonstrated different removal abilities depending on which heavy metals were used.

Analogue modelling of brittle shear zone propagation across upper crustal morpho-rheological heterogeneities

Crustal shearing of pre-tectonic weak bodies (e.g. salt pillows, igneous pockets) associated with basement strike-slip fault systems is common in nature. Yet the structural pattern arising from the interference between a brittle shear zone and such weak rheological heterogeneities is still not fully explained. In the present work, different sand-box analogue modelling experiments were carried out to better understand, not only the shear zone perturbation effect caused by a strictly rheologic (viscous-weak) anomaly, but also the one arising from a combined morphological perturbation (i.e. traverse topographic crest). Obtained results show that the development of different shear zone deformation patterns is in each case essentially determined by the interplay between: (i) ductile wrenching strain accommodation in the (viscous) weak body; and (ii) coincidence vs. mismatch between main brittle-viscous rheological boundaries and (crest-related) topographic steps. Comparison of the experimentally obtained results with complying natural examples is further discussed, and essentially focused on the NE Atlantic tectono-magmatic interference between the Gloria transform fault and the Tore-Madeira submarine ridge.

Seismological Constraints on the Small‐Scale Heterogeneity in the Lowermost Mantle Beneath East Asia and Implication for Its Mineralogical Origin

AbstractPrevious seismological studies have focused on the large‐scale heterogeneity of the D″ layer beneath East Asia. Here, we use high‐frequency PcP precursors recorded at dense networks in China and Japan to constrain the small‐scale heterogeneity in this region. By forward modeling of the stacks of recorded PcP precursory signal, we find that the small‐scale heterogeneity in the D″ layer beneath East Asia is characterized by a P wave velocity perturbation of 0.1‐0.2% and a dominant length scale of 4‐20 km. Although the resolved length scale is similar to the dimension of the subducted oceanic crust, the weak velocity perturbation is difficult to explain by basaltic rock in the lowermost mantle. Postperovskite transition of the supposed slab might also not be viable for generating weak heterogeneity; thus, new explanations are needed from geodynamics and mineral physics to account for the different strength of the large‐ and small‐scale heterogeneity.

Factors controlling the reservoir accumulation of Triassic Chang 6 Member in Jiyuan-Wuqi area, Ordos Basin, NW China

Abstract In the Triassic Yanchang Formation, Jiyuan-Wuqi area, Ordos Basin, the Chang 6 reservoir is contacted to the Chang 7 high-quality source rock, but the oil pools are unevenly distributed, and complex in oil and water distribution. Through cores observation and fracture statistics, combined with comprehensive analyses of physical property, mercury injection, logging and geochemical data, and comparisons of the sandbodies scales, reservoir physical properties, argillaceous laminae and fractures between source and reservoir in the eastern and western oil-bearing areas and in the central water producing area, it is found that the hydrocarbon accumulation patterns are different in the eastern, central and western areas, and the characteristics of hydrocarbon migration under the background of double-provenance were sorted out. The study results show that the crude oil in the eastern area has different Pr/Ph and sterane distribution from that in the western area. The oil and gas primarily migrated vertically. The high-quality source rocks and favorable source-reservoir-cap combinations lay the foundation for large-scale oil and gas accumulations. Vertically, the oil and gas enrichment is controlled by the scale of sandbody and the difference of physical properties, while on the plane, it is controlled by the connectivity of sandbodies, the argillaceous laminae between source rock and reservoir, the reservoir physical property and the fractures. The sandbodies of oil-rich zones in the eastern and western areas have large thickness, low shale content, good physical properties, weak heterogeneity, few argillaceous laminae and abundant fractures, all of which are favorable for the vertical migration and accumulation of oil and gas. In contrast, in the middle area with converging provenances, the reservoirs, composed of thin sandbodies, features rapid variation in lithology and physical properties, strong heterogeneity, poor continuity of sandbodies, abundant argillaceous laminae between source rock and reservoir, and few fractures, makes it difficult for the oil and gas to migrate vertically, and results in low oil enrichment degree ultimately. For the exploration of continental multiple-provenance tight reservoirs, not only the good-property source rocks and reservoirs, but more importantly the source-reservoir contact relationship and the effect of fractures on the hydrocarbon migration and accumulation should be considered.

Nondestructive Mapping of Long-Range Dislocation Strain Fields in an Epitaxial Complex Metal Oxide.

The misfit dislocations formed at heteroepitaxial interfaces create long-ranging strain fields in addition to the epitaxial strain. For systems with strong lattice coupling, such as ferroic oxides, this results in unpredictable and potentially debilitating functionality and device performance. In this work, we use dark-field X-ray microscopy to map the lattice distortions around misfit dislocations in an epitaxial film of bismuth ferrite (BiFeO3), a well-known multiferroic. We demonstrate the ability to precisely quantify weak, long-ranging strain fields and their associated symmetry lowering without modifying the mechanical state of the film. We isolate the screw and edge components of the individual dislocations and show how they result in weak charge heterogeneities via flexoelectric coupling. We show that even systems with small lattice mismatches and additional mechanisms of stress relief (such as mechanical twinning) may still give rise to measurable charge and strain heterogeneities that extend over mesoscopic length scales. This sets more stringent physical limitations on device size, dislocation density, and the achievable degree of lattice mismatch in epitaxial systems.