Liuwei Dihuang pills attenuate ovariectomy-induced bone loss by alleviating bone marrow mesenchymal stem cell (BMSC) senescence via the Yes-associated protein (YAP)-autophagy axis.

CONTEXT: Liuwei Dihuang pill (LWDH) has been used to treat postmenopausal osteoporosis (PMOP). OBJECTIVE: To explore the effects and mechanisms of action of LWDH in PMOP. MATERIALS AND METHODS: Forty-eight female Sprague-Dawley rats were divided into four groups: sham-operated (SHAM), ovariectomized (OVX), LWDH high dose (LWDH-H, 1.6 g/kg/d) and LWDH low dose (LWDH-L, 0.8 g/kg/d); the doses were administered after ovariectomy via gavage for eight weeks. After eight weeks, the bone microarchitecture was evaluated. The effect of LWDH on the differentiation of bone marrow mesenchymal stem cells (BMSCs) was assessed via osteogenesis- and lipogenesis-induced BMSC differentiation. The senescence-related biological indices were also detected using senescence staining, cell cycle analysis, quantitative real-time polymerase chain reaction and western blotting. Finally, the expression levels of autophagy-related proteins and Yes-associated protein (YAP) were evaluated. RESULTS: LWDH-L and LWDH-H significantly modified OVX-induced bone loss. LWDH promoted osteogenesis and inhibited adipogenesis in OVX-BMSCs. Additionally, LWDH decreased the positive ratio of senescence OVX-BMSCs and improved cell viability, cell cycle, and the mRNA and protein levels of p53 and p21. LWDH upregulated the expression of autophagy-related proteins, LC3, Beclin1 and YAP, in OVX-BMSCs and downregulated the expression of p62. DISCUSSION AND CONCLUSIONS: LWDH improves osteoporosis by delaying the BMSC senescence through the YAP-autophagy axis.

Endometriosis of the skeletal muscular system (ESMS): a systematic review.

BACKGROUND: Extrapelvic endometriosis occurring at skeletal muscle and joint sites is not rare and is prone to delayed diagnosis and inappropriate treatment. Herein, endometriosis of the skeletal muscular system (ESMS) is systematically reviewed to facilitate early diagnosis and treatment. METHODS: Literature on ESMS published before March 2022 was retrieved from the Ovid Medline and Web of Science databases, and the major clinical data were extracted for descriptive analysis. RESULTS: A total of 62 studies (78 ESMS cases) met these requirements. The ESMS included the abdominal muscles (50.7%), pelvic floor muscles (11.6%), lower limb muscles (11.6%), hip muscles (8.7%), lumbar muscles (7.2%), joints (5.8%), upper limb muscles (2.9%), and shoulder-neck muscles (1.4%). The age was 34.0 ± 7.2 years (range 17-49 years). Approximately 63.8% of patients had at least one previous pelvic surgery, and 76.8% of local symptoms were related to the menstrual cycle. The course of disease was 29.6 ± 25.4 months (range 0.5-96 months). Only 30.3% of the patients sought initial medical advice from gynecologists, while 69.7% sought initial medical advice from a nongynecological physician. Twenty-seven patients underwent fine-needle aspiration (FNA) under ultrasound or CT monitoring, and only 44.4% (12/27) were confirmed to have endometriosis by FNA tissue pathology. Approximately 47.4% (37/78) of the patients had a normal pelvic cavity appearance. Surgical resection was performed in 92.3% (72/78) of the patients, of whom 88.9% (64/72) underwent complete resection of the lesion (negative surgical margin) and 20.8% (15/72) received postoperative hormone therapy. At 16.7 months of follow-up, 83.3%, 13.8%, 2.9%, and four patients had complete response, partial response, recurrence, and permanent function impairment, respectively. CONCLUSION: Endometriosis can occur at almost any site in the musculoskeletal system. For women of reproductive age with catamenial pain or a mass in the musculoskeletal system, endometriosis should be suspected. Fine-needle aspiration can easily lead to missed diagnoses. Surgical resection for negative margins is the main treatment, and permanent impairment of function may occur in a few patients due to delayed diagnosis. Vascular lymphatic metastasis is the most likely mechanism of pathogenesis.

Mesoscale Aggregation of Sulfur-Rich Asphaltenes: In Situ Microscopy and Coarse-Grained Molecular Simulation.

Asphaltene aggregation is critical to many natural and industrial processes, from groundwater contamination and remediation to petroleum utilization. Despite extensive research in the past few decades, the fundamental process of sulfur-rich asphaltene aggregation still remains not fully understood. In this work, we have investigated the particle-by-particle growth of aggregates formed with sulfur-rich asphaltene by a combined approach of in situ microscopy and molecular simulation. The experimental results show that aggregates assembled from sulfur-rich asphaltene have morphologies with time-dependent structural self-similarity, and their growth rates are aligned with a crossover behavior between classic reaction-limited aggregation and diffusion-limited aggregation. Although the particle size distribution predicted using the Smoluchowski equation deviates from the observations at the initial stage, it provides a reasonable prediction of aggregate size distribution at the later stage, even if the observed cluster coalescence has an important effect on the corresponding cluster size distribution. The simulation results show that aliphatic sulfur exerts nonmonotonic effects on asphaltene nanoaggregate formation depending on the asphaltene molecular structure. Specifically, aliphatic sulfur has a profound effect on the structure of rod-like nanoaggregates, especially when asphaltene molecules have small aromatic cores. Interactions between aliphatic sulfur and the side chain of neighboring molecules account for the repulsive forces that largely explain the polydispersity in the nanoaggregates and corresponding colloidal aggregates. These results can improve our current understanding of the complex process of sulfur-rich asphaltene aggregation and sheds light on designing efficient crude oil utilization and remediation technologies.

Important Role of Concave Surfaces in Deposition of Colloids under Favorable Conditions as Revealed by Microscale Visualization.

This study conducted saturated column experiments to systematically investigate deposition of 1 µm positively charged polystyrene latex micro-colloids (representing microplastic particles) on negatively charged rough sand, glass beads, and soil with pore water velocities (PWV) from 4.9 × 10-5 to 8.8 × 10-4 m/s. A critical value of PWV was found below which colloidal attachment efficiency (AE) increased with increasing PWV. The increase in AE with PWV was attributed to enhanced delivery of the colloids and subsequent attachment at concave locations of rough collector surfaces. The AE decreased with further increasing PWV beyond the threshold because the convex sites became unavailable for colloid attachment. By simulating the rough surfaces using the Weierstrass-Mandelbrot equation, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) interaction energy calculations and torque analysis revealed that the adhesive torques could be reduced to be comparable or smaller than hydrodynamic torques even under the favorable conditions. Interestingly, scanning electron microscopic experiments showed that blocking occurred at convex sites at all ionic strengths (ISs) (e.g., even when the colloid-colloid interaction was attractive), whereas at concave sites, blocking and ripening (i.e., attached colloids favor subsequent attachment) occurred at low and high ISs, respectively. To our knowledge, our work was the first to show coexistence of blocking and ripening at high ISs due to variation of the collector surface morphology.

Colloid Interaction Energies for Surfaces with Steric Effects and Incompressible and/or Compressible Roughness.

Colloid aggregation and retention in the presence of macromolecular coatings (e.g., adsorbed polymers, surfactants, proteins, biological exudates, and humic materials) have previously been correlated with electric double layer interactions or repulsive steric interactions, but the underlying causes are not fully resolved. An interaction energy model that accounts for double layer, van der Waals, Born, and steric interactions as well as nanoscale roughness and charge heterogeneity on both surfaces was extended, and theoretical calculations were conducted to address this gap in knowledge. Macromolecular coatings may produce steric interactions in the model, but non-uniform or incomplete surface coverage may also create compressible nanoscale roughness with a charge that is different from the underlying surface. Model results reveal that compressible nanoscale roughness reduces the energy barrier height and the magnitude of the primary minimum at separation distances exterior to the adsorbed organic layer. The depth of the primary minimum initially alters (e.g., increases or decreases) at separation distances smaller than the adsorbed organic coating because of a decrease in the compressible roughness height and an increase in the roughness fraction. However, further decreases in the separation distance create strong steric repulsion that dominates the interaction energy profile and limits the colloid approach distance. Consequently, adsorbed organic coatings on colloids can create shallow primary minimum interactions adjacent to organic coatings that can explain enhanced stability and limited amounts of aggregation and retention that have commonly been observed. The approach outlined in this manuscript provides an improved tool that can be used to design adsorbed organic coatings for specific colloid applications or interpret experimental observations.

Extracellular polymeric substances induced cell-surface interactions facilitate bacteria transport in saturated porous media.

Bacteria often respond to dynamic soil environment through the secretion of extracellular polymeric substances (EPS). The EPS modifies cell surface properties and soil pore-scale hydration status, which in turn, influences bacteria transport in soil. However, the effect of soil particle size and EPS-mediated surface properties on bacterial transport in the soil is not well understood. In this study, the simultaneous impacts of EPS and collector size on Escherichia coli (E. coli) transport and deposition in a sand column were investigated. E. coli transport experiments were carried out under steady-state flow in saturated columns packed with quartz sand with different size ranges, including 0.300-0.425 mm (sand-I), 0.212-0.300 mm (sand-II), 0.106-0.150 mm (sand-III) and 0.075-0.106 mm (sand-IV). Bacterial retention increased with decreasing sand collector size, suggesting that straining played an important role in fine-textured media. Both experiment and simulation results showed a clear drop in the retention rate of the bacterial population with the presence of additional EPS (200 mg L-1) (EPS+). The inhibited retention of cells in sand columns under EPS+ scenario was likely attributed to enhanced bacteria hydrophilicity and electrostatic repulsion between cells and sand particles as well as reduced straining. Calculations of the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) interactions energies revealed that high repulsive energy barrier existed between bacterial cells and sand particles in EPS+ environment, primarily due to high repulsive electrostatic force and Lewis acid-base force, as well as low attractive Lifshitz-van der Waals force, which retarded bacterial population deposition. Steric stabilization of EPS would also prevent the approaching of cells close to the quartz surface and thereby hinder cell attachment. This study was the first to show that EPS reduced bacterial straining in saturated porous media. These findings provide new insight into the functional effects of extrinsic EPS on bacterial transport behavior in the saturated soil environment, e.g., aquifers.

Crustal Density Structure of the Jiuzhaigou Ms7.0 Earthquake Area Revealed by the Barkam-Jiuzhaigou-Wuqi Gravity Profile.

The Barkam-Jiuzhaigou-Wuqi gravity profile extends across the Jiuzhaigou Ms7.0 earthquake (in 2017) zone and passes through several historical big earthquakes' zones. We have obtained Bouguer gravity anomalies along the profile composed of 365 gravity observation stations with Global Positioning System (GPS) coordinates, analyzed the observed data and inverted subsurface density structure. The results show that the Moho depth has a big lateral variation from southwest to northeast, which shallows from 57 km to 43 km with maximum variation up to 14 km within 800 km. The most acute depth change of the Moho is in the boundary region between the Bayan Har block and West Qinling-Qilian block. According to our analysis, it is related to the eastward movement of the Bayan Har block. There are three main pieces of evidence that support it: (1) Density is higher in the east of the Bayan Har block and smaller in the west, which is the same as seismic activity; (2) Two thin low-density layers exist in the upper and middle crust of the Bayan Har block, which may promote inter-layer slip and the Jiuzhaigou Ms7.0 earthquake occurred in the boundary area of the two low-density layers, where the crustal density and Moho surface fluctuate sharply; (3) the GPS velocity field in the southwestern part gravity profile is significantly larger than that of the northeastern part, which is consistent with the density structure. Our studies also suggest that the large undulation of the Moho prevents the movement of the Bayan Har block, and strain is prone to accumulate here. The dynamic background analysis of the crust in this area indicates that the Moho surface uplifts in the West Qinling-Qilian block, which decelerates the eastern migration of material on the Qinghai-Tibet Plateau, and leads to the weak tectonic activity of the north part of the Bayan Har block.

Application of the RUSLE for Determining Riverine Heavy Metal Flux in the Upper Pearl River Basin, China.

A novel model was developed to estimate heavy metal flux at regional scale by using the Revised Universal Soil Loss Equation (RUSLE) to estimate soil erosion. This model was then used to estimate the fluxes of heavy metals including Zn, Cu, Cr, Ni, Cd, and As in three mono-lithologic regions in upper Pearl River Basin including carbonate rock (CR) basin, black shale (BS) basin, and basalt (BT) basin. Results show that the total annual erosions of the watershed were 8.56 × 105 t a -1, 3.26 × 106 t a-1, and 5.09 × 105 t a-1 in CR, BT, and BS basins, respectively. The heavy metal flux was lowest for Cd (0.87 kg km-2 a-1, 0.46 kg km-2 a-1, and 1.07 kg km-2 a-1 in CR, BS, and BT basins, respectively). The heavy metal flux was highest for Zn in CR basin (16.29 kg km-2 a-1), Cr in BS basin (27.25 kg km-2 a-1) and Cu in BT basin (259.59 kg km-2 a-1). These findings have important implication to understand transport and distribution of heavy metals in the Pearl River Basin, and make regulations for controlling of non-point source heavy metal pollution.

Investigation for Synergies of Ionic Strength and Flow Velocity on Colloidal-Sized Microplastic Transport and Deposition in Porous Media Using the Colloidal-AFM Probe.

Studies that explore the transport and retention behavior of colloidal-sized microplastic (MP) with focusing on the governing mechanisms for their attachment and detachment process using colloidal-atomic force microscopy (C-AFM) were still limited. In the present study, multiscale investigations ranging from pore-scale column test to microscale visualization and eventually to nanoscale interfacial and adhesive force measurement were conducted. Pore- and microscale tests were conducted at various flow velocity and over a broad range of IS values and found that IS and flow velocity could synergically impact the deposition of MPs during filtration, in particular under unfavorable condition at small flow velocity. The net difference between the highest and lowest deposition conditions became smaller while flow velocity was decreasing in porous media. However, the net difference between the high and low IS conditions in parallel plate chamber were not sensitive to the change of flow velocity. The measurement from C-AFM suggested that not only the interfacial force but also the adhesive forces changed while MP was approaching/retracting to the collector surface. Information related to the magnitude, location, and occurrence of interfacial/adhesive forces were analyzed. Comparisons of the interaction energy determined from the measured force and ones derived from surface energy components using DLVO theory were conducted to explain the synergies of IS and flow velocity on pathogenic size MPs transport and deposition during filtration.

Dual-optimized adaptive Kalman filtering algorithm based on BP neural network and variance compensation for laser absorption spectroscopy.

A dual-optimized adaptive Kalman filtering (DO-AKF) algorithm based on back propagation (BP) neural network and variance compensation was developed for high-sensitivity trace gas detection in laser spectroscopy. The BP neural network was used to optimize the Kalman filter (KF) parameters. Variance compensation was introduced to track the state of the system and to eliminate the variations in the parameters of dynamic systems. The proposed DO-AKF algorithm showed the best performance compared with the traditional multi-signal average, extended KF, unscented KF, KF optimized by BP neural network (BP-KF) and KF optimized by variance compensation (VC-KF). The optimized DO-AKF algorithm was applied to a QCL-based gas sensor system for an exhaled CO analysis. The experimental results revealed a sensitivity enhancement factor of 23. The proposed algorithm can be widely used in the fields of environmental pollutant monitoring, industrial process control, and breath gas diagnosis.

Chemical Aging Changed Aggregation Kinetics and Transport of Biochar Colloids.

Little is known about aggregation and transport behaviors of aged biochar colloids in the terrestrial environment. This study investigated aggregation kinetics and transport of biochar colloids from aged (HNO3 treatment) and pristine pinewood biochars pyrolyzed at 300 and 600 °C (PB300 and PB600) in NaCl and CaCl2 solutions. In NaCl solutions, critical coagulation concentrations (CCCs) of aged PB300 and PB600 colloids (540 mM and 327 mM) were much greater than the CCCs of pristine biochar colloids (300 mM and 182 mM). This is likely due to substantial increase of negatively charged oxygen-containing functional groups (primarily carboxyl) on aged biochar surfaces. Intriguingly, in CaCl2 solutions the CCCs of the aged PB300 and PB600 colloids decreased to 25.2 mM and 32.1 mM from 58.6 mM and 41.7 mM for the pristine colloids, respectively. This probably resulted from greater surface charge neutralization and Ca2+ bridging for the aged biochar colloids. In salt solutions (e.g., 10 and 50 mM NaCl and 1 and 10 mM CaCl2), the aged biochar colloids showed higher mobility in porous media than the pristine biochar colloids. This study demonstrated that pristine and aged biochar colloids were stable in the solutions with environmentally relevant ionic strength, and the aging process might substantially increase their mobility in the subsurface.

Next-Generation Multifunctional Carbon-Metal Nanohybrids for Energy and Environmental Applications.

Nanotechnology has unprecedentedly revolutionized human societies over the past decades and will continue to advance our broad societal goals in the coming decades. The research, development, and particularly the application of engineered nanomaterials have shifted the focus from "less efficient" single-component nanomaterials toward "superior-performance", next-generation multifunctional nanohybrids. Carbon nanomaterials (e.g., carbon nanotubes, graphene family nanomaterials, carbon dots, and graphitic carbon nitride) and metal/metal oxide nanoparticles (e.g., Ag, Au, CdS, Cu2O, MoS2, TiO2, and ZnO) combinations are the most commonly pursued nanohybrids (carbon-metal nanohybrids; CMNHs), which exhibit appealing properties and promising multifunctionalities for addressing multiple complex challenges faced by humanity at the critical energy-water-environment (EWE) nexus. In this frontier review, we first highlight the altered and newly emerging properties (e.g., electronic and optical attributes, particle size, shape, morphology, crystallinity, dimensionality, carbon/metal ratio, and hybridization mode) of CMNHs that are distinct from those of their parent component materials. We then illustrate how these important newly emerging properties and functions of CMNHs direct their performances at the EWE nexus including energy harvesting (e.g., H2O splitting and CO2 conversion), water treatment (e.g., contaminant removal and membrane technology), and environmental sensing and in situ nanoremediation. This review concludes with identifications of critical knowledge gaps and future research directions for maximizing the benefits of next-generation multifunctional CMNHs at the EWE nexus and beyond.

DLVO Interaction Energies for Hollow Particles: The Filling Matters.

A thorough knowledge of the interaction energy between a hollow particle (HP) and a surface or between two HPs is critical to the optimization of HP-based products and assessing the environmental risks of HPs and HP-associated pollutants. The van der Waals (vdW) energy between a HP and a surface is often calculated by subtracting the vdW energies of the inner and outer HP geometries. In this study, we show that this subtraction method is only valid when the interior and exterior fluids are the same, for example, for water-filled HPs (WHPs) dispersed in an aqueous solution. Expressions were developed to calculate the vdW energies for HPs whose interiors were filled with air (AHPs). The vdW energies were then calculated between a planar surface and a spherical or cylindrical WHP and AHP, and between WHPs or AHPs. The vdW attraction between a surface and a WHP was decreased at large separation distances compared to solid particles, and this reduced the depth of the secondary minimum. In contrast, the vdW attraction for AHPs and a surface was significantly reduced at all separation distances, and even became repulsive for thin shells, and this inhibited both primary and secondary minimum interactions. The vdW attraction between WHPs decreased with increasing shell thicknesses, and this reduced aggregation in both primary and secondary minima. In contrast, aggregation of AHPs was increased in both minima with decreasing shell thicknesses because of an increase in vdW attraction. Our theoretical calculations show the evolution of vdW and total interaction energies for HPs with different interior fluids and shell thicknesses. These results help explain various experimental observations such as inhibited attachment and favorable aggregation for AHPs (e.g., carbon nanotubes) and favorable bubble coalescence.

Contributions of Nanoscale Roughness to Anomalous Colloid Retention and Stability Behavior.

All natural surfaces exhibit nanoscale roughness (NR) and chemical heterogeneity (CH) to some extent. Expressions were developed to determine the mean interaction energy between a colloid and a solid-water interface, as well as for colloid-colloid interactions, when both surfaces contain binary NR and CH. The influence of heterogeneity type, roughness parameters, solution ionic strength (IS), mean zeta potential, and colloid size on predicted interaction energy profiles was then investigated. The role of CH was enhanced on smooth surfaces with larger amounts of CH, especially for smaller colloids and higher IS. However, predicted interaction energy profiles were mainly dominated by NR, which tended to lower the energy barrier height and the magnitudes of both the secondary and primary minima, especially when the roughness fraction was small. This dramatically increased the relative importance of primary to secondary minima interactions on net electrostatically unfavorable surfaces, especially when roughness occurred on both surfaces and for conditions that produced small energy barriers (e.g., higher IS, lower pH, lower magnitudes in the zeta potential, and for smaller colloid sizes) on smooth surfaces. The combined influence of roughness and Born repulsion frequently produced a shallow primary minimum that was susceptible to diffusive removal by random variations in kinetic energy, even under electrostatically favorable conditions. Calculations using measured zeta potentials and hypothetical roughness properties demonstrated that roughness provided a viable alternative explanation for many experimental deviations that have previously been attributed to electrosteric repulsion (e.g., a decrease in colloid retention with an increase in solution IS; reversible colloid retention under favorable conditions; and diminished colloid retention and enhanced colloid stability due to adsorbed surfactants, polymers, and/or humic materials).

DLVO Interaction Energies between Hollow Spherical Particles and Collector Surfaces.

The surface element integration technique was used to systematically study Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies/forces between hollow spherical particles (HPs) and a planar surface or two intercepting half planes under different ionic strength conditions. The inner and outer spheres of HPs were concentric (CHP) or in point contact (PHP). In comparison to a solid particle, the attractive van der Waals interaction was reduced with increasing inner radius of the CHP, but the reduction effect was less significant for the CHP at smaller separation distance. Increasing the inner radius for CHP therefore reduced the depths of the secondary minima, but had minor influence on the energy barrier heights and depths of the primary minima. Consequently, increasing inner radius reduced the potential for CHP retention in secondary minima, whereas did not influence the retention in primary minima. For PHP these interaction energy parameters and colloid retention depended on the orientation of the inner sphere relative to interacting surface. In particular, the van der Waals attraction was significantly reduced at all separation distances when the inner sphere was closest to the interacting surface, and this diminished retention in both secondary and primary minima. The PHP retention was similar to that of CHP when the inner sphere was farthest from the interaction surface. These orientation dependent interaction energies/forces resulted in directional bonds between PHPs and the formation of aggregates with contact points of the primary PHPs facing outward. The findings in this study have important implications for the design and utilization of HPs in soil remediation and colloid assembly.

Observed Dependence of Colloid Detachment on the Concentration of Initially Attached Colloids and Collector Surface Heterogeneity in Porous Media.

Sand column experiments were conducted to examine the effects of the concentration of attached colloids (CAC) on their subsequent detachment upon decreasing solution ionic strength (IS). Different pore volumes of latex microparticle suspensions were injected into the columns to allow different amounts of colloids to attach at ISs of 0.001, 0.01, and 0.2 M. Then, deionized water was introduced to release the attached colloids. Results show that the fraction of attachments that were reversible to reduction of IS (FRA) increased with increasing CAC at a given IS if the sand was extensively treated using acids to reduce surface charge heterogeneity. This indicates that colloids were preferentially immobilized in sites favoring irreversible attachment and then gradually occupied reversible sites. In contrast, the FRA decreased with increasing CAC at 0.001 M in sand without the acid treatment, illustrating the opposite attachment sequence. Scanning electron microscope examinations reveal that the concave regions favored irreversible colloid attachment. Reversible attachment is likely due to immobilization on flat surfaces with charge heterogeneities, retention in stagnation point regions via secondary minimum association, ripening in the acid-treated sand, and capture of colloids by protruding asperities with charge heterogeneity in the untreated sand. At ISs of 0.01 and 0.2 M, the FRA was essentially independent of CAC in the untreated sand because the colloids were randomly attached on the sand surfaces over time.

Influence of Biochar on Deposition and Release of Clay Colloids in Saturated Porous Media.

Although the potential application of biochar in soil remediation has been recognized, the effect of biochar on the transport of clay colloids, and accordingly the fate of colloid-associated contaminants, is unclear to date. This study conducted saturated column experiments to systematically examine transport of clay colloids in biochar-amended sand porous media in different electrolytes at different ionic strengths. The obtained breakthrough curves were simulated by the convection-diffusion equation, which included a first-order deposition and release terms. The deposition mechanisms were interpreted by calculating Derjaguin-Landau-Verwey-Overbeek interaction energies. A linear relationship between the simulated deposition rate or the attachment efficiency and the fraction of biochar was observed ( ≥ 0.91), indicating more favorable deposition in biochar than in sand. The interaction energy calculations show that the greater deposition in biochar occurs because the half-tube-like cavities on the biochar surfaces favor deposition in secondary minima and the nanoscale physical and chemical heterogeneities on the biochar surfaces increase deposition in primary minima. The deposited clay colloids in NaCl can be released by reduction of ionic strength, whereas the presence of a bivalent cation (Ca) results in irreversible deposition due to the formation of cation bridging between the colloids and biochar surfaces. The deposition and release of clay colloids on or from biochar surfaces not only change their mobilizations in the soil but also influence the efficiency of the biochar for removal of pollutants. Therefore, the influence of biochar on clay colloid transport must be considered before application of the biochar in soil remediation.

Co-transport of Pesticide Acetamiprid and Silica Nanoparticles in Biochar-Amended Sand Porous Media.

The role of biochar as a soil amendment on the transport of acetamiprid, a widely used neonicotinoid pesticide, is little known. We conducted saturated column experiments to examine cotransport of acetamiprid and silica nanoparticles (NPs) in pure and biochar-amended sands. Retention of acetamiprid was minor in the pure sand, whereas application of biochar in the sand significantly increased retention. Retention was greater at lower ionic strengths and near neutral pH values and was attributed to biodegradation and sorption through π-π interaction and pore filling. The convection-diffusion equation with inclusion of first-order sorption, desorption, and degradation well described the transport of acetamiprid in the biochar-amended sand. The simulation results show that the sorption rate did not change with pH. This is because the acetamiprid is nonionic and cannot be bonded with the biochar by protonation or deprotonation. The desorption rate was independent of variation of solution chemistry, indicating that desorption was a physical process (i.e., pore diffusion). Application of biochar in the sand had little influence on the transport of silica NPs in NaCl but caused complete attachment in CaCl. Energy dispersive X-ray spectroscopy suggested that the enhanced attachment was due to cation bridging between silica NPs and functional groups in biochar by the Ca. The co-presence of acetamiprid and silica NPs in the solutions enhanced transport of acetamiprid and NPs in the biochar-amended sand by competing for the binding sites on the biochar surfaces.

Effective removal of nemacide fosthiazate from an aqueous solution using zero-valent iron.

In this study, the removal of fosthiazate in an aqueous solution using zero valent iron (ZVI) and the related removal reaction mechanism were investigated. The results indicate that the dissipation of fosthiazate adheres to a pseudo-first order reaction law. The apparent rate constant of fosthiazate removal could be improved by increasing the ZVI dosage, control temperature and initial pH. The observed pseudo-first-order degradation rate constants (Kobs) of fosthiazate removal using ZVI were varied in the different electrolyte solutions, and were determined as follows: Kobs (MgSO4) < Kobs (KCl) < Kobs (Control)

Spatial variability of available soil microelements in an ecological functional zone of Beijing.

Understanding the spatial variability of soil microelements and its influencing factors is of importance for a number of applications such as scientifically formulated fertilizer and environmental protection. This study used descriptive statistics and geostatistics to investigate the spatial variability of available soil Fe, Mn, Cu, and Zn contents in agricultural topsoil (0-20 cm) in an ecological functional zone located at Yanqing County, Beijing, China. Kriging method was applied to map the spatial patterns of available soil Fe, Mn, Cu, and Zn contents. Results showed that the available soil Cu had a widest spatial correlation distance (e.g., 9.6 km), which for available soil Fe, Mn, and Zn were only 1.29, 2.58, and 0.99 km, respectively. The values of C 0/sill for available soil Fe and Zn were 0.12 and 0.11, respectively, demonstrating that the spatial heterogeneity was mainly due to structural factors. The available soil Mn and Cu had the larger values of C 0/sill (i.e., 0.50 and 0.44 for Mn and Cu, respectively), which showed a medium spatial correlation. Mapping of the spatial patterns of the four microelements showed that the decrease trend of available soil Fe and Mn were from northeast to southwest across the study area. The highest amount of available soil Cu was distributed in the middle of the study area surrounding urban region which presented as a "single island". The highest amount of available soil Zn was mainly distributed in the north and south of the study area. One-way analysis of variance for the influencing factors showed that the lithology of parental materials, soil organic matter, and pH were important factors affecting spatial variability of the available microelements. The topography only had a significant influence on the spatial variability of available soil Fe and Mn contents, parental materials, and the land use types had little influence on the spatial variability.