Dual roles of goethite coating on the transport of plastic nanoparticles in heterogeneous porous media: The significance of collector surface roughness.

This study systematically examines the roles of positive goethite on the retention and release of negative plastic nanoparticles (PSNPs) with different surface functional groups (Blank, -COOH, and -NH2). It provides the first evidence for the dual roles of goethite coatings on colloid transport; e.g., increased transport caused by surface morphology modification or decreased transport due to increased surface roughness and charge heterogeneity. Although previous work has shown that goethite-coated sand increases the retention of negative colloids, this work demonstrates that collector surface roughness can also reduce the retention of PSNPs due to increased interaction energy profiles. Nonmonotonic retention of all the different functionalized PSNPs was observed in goethite-coated rough sand, and the magnitude of variations was contingent on the PSNP functionalization, the solution ionic strength (IS), and the goethite coating. The release of PSNPs with IS decrease (phase I) and pH increase (phase II) varied significantly due to differences in energy barriers to detachment, e.g., release in phase I was inhibited in both goethite-coated sands, whereas release in phase II was enhanced in coated smooth sand but completely inhibited in rough sand. The findings of this study provide innovative insight into transport mechanisms for colloidal and colloid-associated contaminants.

Comparison of the therapeutic effects of mesenchymal stem cells derived from human dental pulp (DP), adipose tissue (AD), placental amniotic membrane (PM), and umbilical cord (UC) on postmenopausal osteoporosis.

Background: Osteoporosis is a systemic bone disease characterized by bone loss and microstructural degeneration. Recent preclinical and clinical trials have further demonstrated that the transplantation of mesenchymal stem cells (MSCs) derived from human adipose tissue (AD), dental pulp (DP), placental amniotic membrane (AM), and umbilical cord (UC) tissues can serve as an effective form of cell therapy for osteoporosis. However, MSC-mediated osteoimmunology and the ability of these cells to regulate osteoclast-osteoblast differentiation varies markedly among different types of MSCs. Methods: In this study, we investigated whether transplanted allogeneic MSCs derived from AD, DP, AM, and UC tissues were able to prevent osteoporosis in an ovariectomy (OVX)-induced mouse model of osteoporosis. The homing and immunomodulatory ability of these cells as well as their effects on osteoblastogenesis and the maintenance of bone formation were compared for four types of MSCs to determine the ideal source of MSCs for the cell therapy-based treatment of OVX-induced osteoporosis. The bone formation and bone resorption ability of these four types of MSCs were analyzed using micro-computed tomography analyses and histological staining. In addition, cytokine array-based analyses of serological markers and bioluminescence imaging assays were employed to evaluate cell survival and homing efficiency. Immune regulation was determined by flow cytometer assay to reflect the mechanisms of osteoporosis treatment. Conclusion: These analyses demonstrated that MSCs isolated from different tissues have the capacity to treat osteoporosis when transplanted in vivo. Importantly, DP-MSCs infusion was able to maintain trabecular bone mass more efficiently with corresponding improvements in trabecular bone volume, mineral density, number, and separation. Among the tested MSC types, DP-MSCs were also found to exhibit greater immunoregulatory capabilities, regulating the Th17/Treg and M1/M2 ratios. These data thus suggest that DP-MSCs may represent an effective tool for the treatment of osteoporosis.

Dual-Band All-Optical Logic Gates by Coherent Absorption in an Amorphous Silicon Graphene Metasurface.

The dual-band polarization-independent all-optical logic gate by coherent absorption effect in an amorphous silicon (a-Si) graphene metasurface is investigated theoretically and numerically. Taking the substrate effect into consideration, the coherent perfect absorption condition of the a-Si graphene metasurface is derived on the basis of the Cartesian multipole method. The coherent nearly perfect absorption of the a-Si graphene metasurface is realized by the interference of multipole moments and the interband transition of monolayer graphene, achieving peak values of 91% and 92% at 894.5 nm and 991.5 nm, respectively. The polarization independence of the coherent absorption is revealed due to the center symmetry of the structure of the a-Si graphene metasurface. The dual-band polarization-independent all-optical XOR and OR logic gates are implemented at 894.5 nm and 991.5 nm by the a-Si graphene metasurface based on the coherent nearly perfect absorption, which has the opportunity to be utilized in all-optical computing, all-optical data processing, and future all-optical networks.

EPO regulates the differentiation and homing of bone marrow mesenchymal stem cells through Notch1/Jagged pathway to treat pulmonary hypertension.

Purpose: To investigate whether erythropoietin (EPO) can treat pulmonary arterial hypertension (PAH) in rats by regulating the differentiation and homing of bone marrow mesenchymal stem cells (BMSCs) through Notch1/Jagged signaling pathway. Materials & methods: BMSCs were isolated from the bone marrow of 6-week-old male SD rats by whole bone marrow method and identified. BMSCs were treated with 500 IU/mL EPO, and the proliferation, migration, invasion and differentiation ability, and the expression of MMP-2 and MMP-9 protein of BMSCs were detected in vitro. After the establishment of the pulmonary hypertension model in rats, BMSCs were intervened with different concentrations of EPO and injected into the rats through intravenous injection. The levels of TNF-α, IL-1ß and IL-6 in lung tissue, the expression of SRY CXCR4, CCR2, Notch1 and Jagged protein in lung tissue, and the levels of TGF-α, vascular endothelial factor (VEGF), IGF-1 and HGF in serum were detected. Immunofluorescence (IF) staining was used to detect the co-localization of CD34. Results: EPO promoted the proliferation, migration, and invasion of BMSCs by inhibiting Notch1/Jagged pathway in vitro, and induced BMSCs to differentiate into vascular smooth muscle cells and vascular endothelial cells. EPO inhibited Notch1/Jagged pathway in PAH rats, induced BMSCs homing and differentiation, increased the levels of TGF-α, VEGF, IGF-1 and HGF, and decreased the levels of TNF-α, IL-1ß and IL-6. Discussion & conclusion: EPO can inhibit the Notch1/Jagged pathway and promote the proliferation, migration, invasion, homing and differentiation of BMSCs to treat pulmonary hypertension in rats in vitro and in vivo.

The impact of induced pluripotent stem cells in animal conservation.

It is widely acknowledged that we are currently facing a critical tipping point with regards to global extinction, with human activities driving us perilously close to the brink of a devastating sixth mass extinction. As a promising option for safeguarding endangered species, induced pluripotent stem cells (iPSCs) hold great potential to aid in the preservation of threatened animal populations. For endangered species, such as the northern white rhinoceros (Ceratotherium simum cottoni), supply of embryos is often limited. After the death of the last male in 2019, only two females remained in the world. IPSC technology offers novel approaches and techniques for obtaining pluripotent stem cells (PSCs) from rare and endangered animal species. Successful generation of iPSCs circumvents several bottlenecks that impede the development of PSCs, including the challenges associated with establishing embryonic stem cells, limited embryo sources and immune rejection following embryo transfer. To provide more opportunities and room for growth in our work on animal welfare, in this paper we will focus on the progress made with iPSC lines derived from endangered and extinct species, exploring their potential applications and limitations in animal welfare research.

Acidithiobacillus species drive the formation of ferric-silica cemented microstructure: Insights into early hardpan development for mine site rehabilitation.

Hardpan-based profiles naturally formed under semi-arid climatic conditions have substantial potential in rehabilitating sulfidic tailings, resulting from their aggregation microstructure regulated by Fe-Si cements. Nevertheless, eco-engineered approaches for accelerating the formation of complex cementation structure remain unclear. The present study aims to investigate the microbial functions of extremophiles on mineral dissolution, oxidation, and aggregation (cementation) through a microcosm experiment containing pyrites and polysilicates, of which are dominant components in typical sulfidic tailings. Microspectroscopic analysis revealed that pyrite was rapidly dissolved and massive microbial corrosion pits were displayed on pyrite surfaces. Synchrotron-based X-ray absorption spectroscopy demonstrated that approximately 30 % pyrites were oxidized to jarosite-like (ca. 14 %) and ferrihydrite-like minerals (ca. 16 %) in talc group, leading to the formation of secondary Fe precipitates. The Si ions co-dissolved from polysilicates may be embedded into secondary Fe precipitates, while these clustered Fe-Si precipitates displayed distinct morphology (e.g., "circular" shaped in the talc group, "fine-grained" shaped in the chlorite group, and "donut" shaped in the muscovite group). Moreover, the precipitates could join together and act as cementing agents aggregating mineral particles together, forming macroaggregates in talc and chlorite groups. The present findings revealed critical microbial functions on accelerating mineral dissolution, oxidation, and aggregation of pyrite and various silicates, which provided the eco-engineered feasibility of hardpan-based technology for mine site rehabilitation.

Erythropoietin improves pulmonary hypertension by promoting the homing and differentiation of bone marrow mesenchymal stem cells in lung tissue.

Pulmonary arterial hypertension (PAH) is a chronic disease thatultimately progresses to right-sided heart failure and death. Erythropoietin (EPO) has been shown to have therapeutic potential in cardiovascular diseases, including PAH. In this study, we aimed to investigate the improvement effect of EPO pretreated bone marrow mesenchymal stem cells (BMSCs) on PAH. BMSCs were obtained from the bone marrow of male SD rats. Female rats were randomly divided into six groups, including control group, monocrotaline (MCT)-induced group, and four groups with different doses of EPO pretreated BMSCs. Lung tissue was taken for testing at 2 weeks of treatment. Our results showed EPO promoted homing and endothelial cell differentiation of BMSCs in the lung tissues of PAH rats. EPO and BMSCs treatment attenuated pulmonary arterial pressure, polycythemia, and pulmonary artery structural remodeling. Furthermore, BMSCs inhibited pulmonary vascular endothelial-to-mesenchymal transition (EndoMT) in PAH rats, which was further suppressed by EPO in a concentration-dependent manner. Meanwhile, EPO and BMSC treatment elevated pulmonary angiogenesis in PAH rats. BMSCs inhibited TNF-α, IL-1ß, IL-6, and MCP-1 in lung tissues of PAH rats, which was further decreased by EPO in a concentration-dependent manner. Thus, EPO improved pulmonary hypertension (PH) by promoting the homing and differentiation of BMSCs in lung tissue.

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.

Effects of Periplaneta americana extracts on the growth and proliferation of cutaneous interstitial cells in cutaneous-wound healing.

Cutaneous-wound healing requires a coordinated reaction of multiple cells, including interstitial cells. Impaired recovery of cutaneous wounds can lead to various adverse health outcomes. Kangfuxin (KFX), an extract obtained from Periplaneta americana, is beneficial in cutaneous-wound healing. In this study, we isolated dermal cells from suckling mice and established a mouse model of cutaneous injury to evaluate the therapeutic effects of KFX. Cell biology experiments indicated that treatment with KFX improved cell proliferation and migration and also repaired cutaneous wounds in the animal model. Activation of the signal transducer and activator of transcription 3 (STAT3) signaling pathway was the core molecular mechanism of KFX. Our study provides a theoretical and practical basis for the clinical application of KFX in cutaneous-wound healing.

Significant Mobility of Novel Heteroaggregates of Montmorillonite Microparticles with Nanoscale Zerovalent Irons in Saturated Porous Media.

This study conducted laboratory column experiments to systematically examine the transport of novel heteroaggregates of montmorillonite (Mt) microparticles with nanoscale zerovalent irons (nZVIs) in saturated sand at solution ionic strengths (ISs) ranging from 0.001 to 0.2 M. Spherical nZVIs were synthesized using the liquid phase reduction method and were attached on the plate-shaped Mt surfaces in monolayer. While complete deposition occurred for nZVIs in sand, significant transport was observed for Mt-nZVI heteroaggregates at IS ≤ 0.01 M despite the transport decrease with an increasing loading concentration of nZVIs on Mt. The increased mobility of Mt-nZVI heteroaggregates was because the attractions between nZVIs and sand collectors were reduced by the electrostatic repulsions between the Mt and the collector surfaces, which led to a decreased deposition in the sand columns. Complete deposition occurred for the Mt-nZVI heteroaggregates at IS ≥ 0.1 M due to a favorable deposition at Derjaguin-Landau-Verwey-Overbeek (DLVO) primary energy minima. Interestingly, a large fraction of the deposited heteroaggregates was released by reducing IS because of a monotonic decrease of interaction energy with separation distance for the heteroaggregates at low ISs (resulting in repulsive forces), in contrast to the irreversible deposition of nZVIs. Therefore, the fabricated heteroaggregates could also have high mobility in subsurfaces with saline pore water through continuous capture and release using multiple injections of water with low ISs. Our study was the first to examine the transport of heteroaggregates of a plate-like particle with spherical nanoparticles in porous media; the results have important implications in the use of nanoscale zerovalent iron for in situ soil and groundwater remediation.

Micro- and nanoplastics retention in porous media exhibits different dependence on grain surface roughness and clay coating with particle size.

The presence and/or coating of natural colloids (e.g., clays and metal oxides or hydroxides) on collector surfaces has frequently been demonstrated to enhance the retention of engineered colloids that are negatively charged due to favorable electrostatic interactions. However, this work demonstrates that the presence of natural clay coating can lead to reduced or nonmonotonic retention of micro- and nanoplastics (MNPs). Column experiments were carried out to systematically investigate the transport of MNPs with different sizes in relatively smooth and rough sands that had various clay coating fractions. These coating fractions on the collector were found to significantly influence MNP retention in a complex manner that changed with the colloid size and the roughness properties of the sand. This observation was attributed to the impact of clay coatings on the roughness and morphology properties of collector surfaces that were dominant over surface charge. Scanning electron microscopy and interaction energy calculations on surfaces with pillars or valleys indicate that mechanisms that contributed to MNP retention changed with the colloid size. In particular, retention of nanosized plastics was mainly controlled by interactions on convex/concave locations that changed with the solution chemistry, whereas microsized plastics were also strongly influenced by the applied hydrodynamic torque and straining processes. Additionally, the significant sensitivity of MNP retention under a low-level ionic strength also reflects the importance of roughness and charge heterogeneities. These observations are important for investigating the mechanisms of colloid transport in natural systems that ubiquitously exhibit clay coating on their surfaces.

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.

Bavachin inhibits IL-4 expression by downregulating STAT6 phosphorylation and GATA-3 expression and ameliorates asthma inflammation in an animal model.

IL-4 plays a key role in many human diseases, including allergic asthma, autoimmunity, allergies, and cancer. Therefore, the investigation of small compounds that regulate IL-4 secretion is of great interest for fighting these diseases. Natural flavonoids are useful compounds reported to have therapeutic effects in diseases involving IL-4. This study aimed to investigate small compounds that inhibit the effect of IL-4 with the lowest cell toxicity. We found that Bavachin had the greatest ability to downregulate IL-4 in the spleen of T cells from 4get IL-4-GFP mice. To identify the underlying molecular mechanisms, we found that Bavachin could decrease the IL-4 levels by downregulating the level of Gata-3 expression and STAT6 phosphorylation. These findings reveal the potential use of Bavachin as a tool for selectively controlling diseases involving IL-4 and, more generally, STAT6-dependent responses.

Hydrogen peroxide and high-temperature heating differently alter the stability and aggregation of black soil colloids.

Chemical oxidation and high-temperature heating have been widely used for the decontamination of soils polluted by hydrocarbons and the removal of soil organic matter. Chemical oxidation and high-temperature heating decreased the stability of soil colloids, but the difference in colloidal stability and aggregation behaviors of soil after chemical oxidation and high-temperature heating is not clear. In this study, taken black soil as an example, we tested the stability profiles of black soil colloids (BC), hydrogen peroxide (H2O2) treated black soil colloids (BC_H2O2), and 350 °C treated black soil colloids (BC_350 °C) in three salt solutions (NaCl, CaCl2, and Na2SO4) with different salt concentrations. The stability of soil colloids in salt solutions was in the order of BC > BC_350 °C > BC_H2O2. The salt concentrations at which three colloids started to be unstable were much lower for CaCl2 solution than those for NaCl and Na2SO4 solution. Salt concentrations that suspension started to be unstable were similar in NaCl and Na2SO4 solution for all the three colloids, but the colloidal stability profile in NaCl solution decreased faster than that in Na2SO4 solution when the suspension was unstable. The stability profiles of three colloids at the fast aggregation stage could be well fitted with the proposed exponential model, and model parameters (t0 and Smax) could reflect the stability behaviors of soil colloids in various salt solutions.

Novel analytical expressions for determining van der Waals interaction between a particle and air-water interface: Unexpected stronger van der Waals force than capillary force.

HYPOTHESIS: Analytical expressions for calculating Hamaker constant (HC) and van der Waals (VDW) energy/force for interaction of a particle with a solid water interface has been reported for over eighty years. This work further developed novel analytical expressions and numerical approaches for determining HC and VDW interaction energy/force for the particle approaching and penetrating air-water interface (AWI), respectively. METHODS: The expressions of HC and VDW interaction energy/force before penetrating were developed through analysis of the variation in free energy of the interaction system with bringing the particle from infinity to the vicinity of the AWI. The surface element integration (SEI) technique was modified to calculate VDW energy/force after penetrating. FINDINGS: We explain why repulsive VDW energy exists inhibiting the particle from approaching the AWI. We found very significant VDW repulsion for a particle at a concave AWI after penetration, which can even exceed the capillary force and cause strong retention in water films on a solid surface and at air-water-solid interface line. The methods and findings of this work are critical to quantification and understanding of a variety of engineered processes such as particle manipulation (e.g., bubble flotation, Pickering emulsion, and particle laden interfaces).

A Plasmonic Infrared Multiple-Channel Filter Based on Gold Composite Nanocavities Metasurface.

A plasmonic near-infrared multiple-channel filter is numerically and experimentally investigated based on a gold periodic composite nanocavities metasurface. By the interference among different excited plasmonic modes on the metasurface, the multipeak extraordinary optical transmission (EOT) phenomenon is induced and utilized to realize multiple-channel filtering. Investigated from the simulated transmission spectrum of the metasurface, the positions and intensity of transmission peaks are tuned by the geometrical parameters of the metasurface and environmental refractive index. The fabricated metasurface approached transmission peaks at 1128 nm, 1245 nm, and 1362 nm, functioning as a three-passbands filter. With advantages of brief single-layer fabrication and multi-frequency selectivity, the proposed plasmonic filter has potential possibilities of integration in nano-photonic switching, detecting and biological sensing systems.

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.

Observed equilibrium partition and second-order kinetic interaction of quantum dot nanoparticles in saturated porous media.

This study integrated batch experiments and theoretical calculations to understand the equilibrium adsorption and kinetic interaction of CdSeS/ZnS alloyed quantum dots nanoparticles (QDNPs) in sand porous media under different ionic strengths (ISs; 0.001-0.2 M NaCl). Our experimental results showed that equilibrium was reached for QDNP concentration between solid phase and bulk solution due to reversible adsorption of the QDNPs on sand surfaces. Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations showed that the repulsive energy barriers were low and primary energy wells were shallow (i.e., comparable to the average kinetic energy of a colloid) at all tested solution ISs. Hence, the QDNPs could mobilize into and simultaneously escape from the primary wells by Brownian diffusion, resulting in the reversible adsorption. Additional batch experiments confirmed that a fraction of adsorbed QDNPs was released even without any perturbation of system conditions. The release was more evident at a lower IS because the primary energy wells spanned more narrowly at low ISs and thus the nanoparticles have a higher possibility to escape out. The batch kinetic experiments showed that the adsorption of QDNPs followed first- and second-order kinetic interactions at low and high ISs, respectively. These results indicate that the well-known colloid filtration theory that assumes irreversible first-order kinetics for colloid deposition is not suitable for describing the QDNP adsorption. The findings in our work can aid better description and prediction of fate and transport of QDNPs in subsurface environments.