A Visual-Inertial Pressure Fusion-Based Underwater Simultaneous Localization and Mapping System.

Detecting objects, particularly naval mines, on the seafloor is a complex task. In naval mine countermeasures (MCM) operations, sidescan or synthetic aperture sonars have been used to search large areas. However, a single sensor cannot meet the requirements of high-precision autonomous navigation. Based on the ORB-SLAM3-VI framework, we propose ORB-SLAM3-VIP, which integrates a depth sensor, an IMU sensor and an optical sensor. This method integrates the measurements of depth sensors and an IMU sensor into the visual SLAM algorithm through tight coupling, and establishes a multi-sensor fusion SLAM model. Depth constraints are introduced into the process of initialization, scale fine-tuning, tracking and mapping to constrain the position of the sensor in the z-axis and improve the accuracy of pose estimation and map scale estimate. The test on seven sets of underwater multi-sensor sequence data in the AQUALOC dataset shows that, compared with ORB-SLAM3-VI, the ORB-SLAM3-VIP system proposed in this paper reduces the scale error in all sequences by up to 41.2%, and reduces the trajectory error by up to 41.2%. The square root has also been reduced by up to 41.6%.

Coremoval of Energetics and Oxyanions via the In Situ Coupling of Catalytic and Enzymatic Destructions: A Solution to Ammunition Wastewater Treatment.

Ammunition wastewater contains toxic nitrated explosives like RDX and oxyanions like nitrate and perchlorate. Its treatment is challenged by low efficiency due to contaminant recalcitrance and high cost due to multiple processes needed for separately removing different contaminant types. This paper reports a H2-based low-energy strategy featuring the treatment of explosives via catalytic denitration followed by microbial mineralization coupled with oxyanion reduction. After a nitrate- and perchlorate-reducing biofilm incapable of RDX biodegradation was coated with palladium nanoparticles (Pd0NPs), RDX was rapidly denitrated with a specific catalytic activity of 8.7 gcat-1 min-1, while biological reductions of nitrate and perchlorate remained efficient. In the subsequent 30-day continuous test, >99% of RDX, nitrate, and perchlorate were coremoved, and their effluent concentrations were below their respective regulation levels. Detected intermediates and shallow metagenome analysis suggest that the intermediates after Pd-catalytic denitration of RDX ultimately were enzymatically utilized by the nitrate- and perchlorate-reducing bacteria as additional electron donor sources.

Phenotypic and Transcriptional Responses of Pseudomonas aeruginosa Biofilms to UV-C Irradiation via Side-Emitting Optical Fibers: Implications for Biofouling Control.

Biofilms give rise to a range of issues, spanning from harboring pathogens to accelerating microbial-induced corrosion in pressurized water systems. Introducing germicidal UV-C (200-280 nm) irradiation from light-emitting diodes (LEDs) into flexible side-emitting optical fibers (SEOFs) presents a novel light delivery method to inhibit the accumulation of biofilms on surfaces found in small-diameter tubing or other intricate geometries. This work used surfaces fully submerged in flowing water that contained Pseudomonas aeruginosa, an opportunistic pathogen commonly found in water system biofilms. A SEOF delivered a UV-C gradient to the surface for biofilm inhibition. Biofilm growth over time was monitored in situ using optical conference tomography. Biofilm formation was effectively inhibited when the 275 nm UV-C irradiance was ≥8 µW/cm2. Biofilm samples were collected from several regions on the surface, representing low and high UV-C irradiance. RNA sequencing of these samples revealed that high UV-C irradiance inhibited the expression of functional genes related to energy metabolism, DNA repair, quorum sensing, polysaccharide production, and mobility. However, insufficient sublethal UV-C exposure led to upregulation genes for SOS response and quorum sensing as survival strategies against the UV-C stress. These results underscore the need to maintain minimum UV-C exposure on surfaces to effectively inhibit biofilm formation in water systems.

Simultaneous biodegradation kinetics of 1,4-dioxane and ethane.

Biodegradation of 1,4-Dioxane at environmentally relevant concentrations usually requires the addition of a primary electron-donor substrate to sustain biomass growth. Ethane is a promising substrate, since it is available as a degradation product of 1,4-Dioxane's common co-contaminants. This study reports kinetic parameters for ethane biodegradation and co-oxidations of ethane and 1,4-Dioxane. Based on experiments combined with mathematical modeling, we found that ethane promoted 1,4-Dioxane biodegradation when the initial mass ratio of ethane:1,4-Dioxane was < 9:1 mg COD/mg COD, while it inhibited 1,4-Dioxane degradation when the ratio was > 9:1. A model-independent estimator was used for kinetic-parameter estimation, and all parameter values for 1,4-Dioxane were consistent with literature-reported ranges. Estimated parameters support competitive inhibition between ethane as the primary substrate and 1,4-Dioxane as the secondary substrate. The results also support that bacteria that co-oxidize ethane and 1,4-Dioxane had a competitive advantage over bacteria that can use only one of the two substrates. The minimum concentration of ethane to sustain ethane-oxidizing bacteria and ethane and 1,4-Dioxane-co-oxidizing bacteria was 0.09 mg COD/L, which is approximately 20-fold lower than the minimum concentration reported for propane, another common substrate used to promote 1,4-Dioxane biodegradation. The minimum 1,4-Dioxane concentration required to sustain steady-state biomass with 1,4-Dioxane as the sole primary substrate was 1.3 mg COD/L. As 1,4-Dioxane concentrations at most groundwater sites are less than 0.18 mg COD/L, providing ethane as a primary substrate is vital to support biomass growth and consequently enable 1,4-Dioxane bioremediation.

Effects of Branched-Chain Fatty Acids Derived from Yak Ghee on Lipid Metabolism and the Gut Microbiota in Normal-Fat Diet-Fed Mice.

Branched-chain fatty acids (BCFAs) are natural components with a variety of biological activities. However, the regulation of lipid metabolism by BCFAs is unknown. It was dedicated to examining the impacts of BCFAs inferred from yak ghee on the expression of qualities related to lipid metabolism, natural pathways, and intestinal microbiota in mice. The treatment group (purified BCFAs from yak ghee) exhibited a decrease in cholesterol levels; a decrease in HMGCR levels; downregulation of FADS1, FADS2, ACC-α, FAS, GAPT4, GPAM, ACSL1, THRSP, A-FABP, and PPARα gene expression; and upregulation of SCD1, ACSS1, FABP1, CPT1, and DGAT-1 gene expression. Gut microbiota 16S rDNA sequencing analysis showed that the treatment group improved the gut microbiota by increasing the relative abundances and increasing the short-chain fatty acid levels produced by the genera Akkermansia, Clostridium, Lachnospiraceae, Lactobacillus, Anaerotaenia, and Prevotella. After adding BCFAs to cultured breast cancer cells, pathways that were downregulated were found to be related to fatty acid degradation and fatty acid metabolism, while 20 other pathways were upregulated. Our results suggest that BCFAs reduce body fat in mice by modulating intestinal flora and lipid metabolism and modulating fatty acid metabolism in breast cancer cells.

Palladium (Pd0) Loading-Controlled Catalytic Activity and Selectivity for Chlorophenol Hydrodechlorination and Hydrosaturation.

Reductive catalysis by zero-valent palladium nanoparticles (Pd0NPs) has emerged as an efficient strategy for promoting the detoxification of chlorophenols (CPs) via hydrogenation. Most studies achieved hydrodechlorination of CP to phenol for detoxification, but it requires considerably high energy input and harsh conditions to further hydrosaturate phenol to cyclohexanone (CHN) as the most desired product for resource recovery. This study documented 4-CP hydrodechlorination and hydrosaturation catalyzed by Pd0NPs deposited on H2-transfer membranes in the H2-based membrane catalyst-film reactor, which yielded up to 99% CHN selectivity under ambient conditions. It was further discovered that the Pd0 morphology and size, both determined by Pd0 loading, were the key factors controlling the catalytic activity and selectivity: while sub-nano Pd particles catalyzed only 4-CP hydrodechlorination, Pd0NPs were able to catalyze the subsequent hydrosaturation that requires more Pd0 reactive sites than hydrodechlorination. In addition, better dispersion of Pd0, caused by lower Pd0 loading, yielded higher activity for hydrodechlorination but lower activity for hydrosaturation. During the 15 day continuous tests, the substantial product from 4-CP hydrogenation was constantly phenol (>98%) for 0.2 g-Pd/m2 and CHN (>92%) for 1.0 g-Pd/m2. This study opens the door for selectively manipulating desired products from Pd0-catalyzed CP hydrogenation under ambient conditions.

Hydrodehalogenation of Trichlorofluoromethane over Biogenic Palladium Nanoparticles in Ambient Conditions.

Among a number of persistent chlorofluorocarbons (CFCs, or freons), the emissions of trichlorofluoromethane (CFCl3, CFC-11) have been increasing since 2002. Zero-valent-Pd (Pd0) catalysts are known to hydrodehalogenate CFCs; however, most studies rely on cost-inefficient and eco-unfriendly chemical synthesis of Pd0NPs and harsh reaction conditions. In this study, we synthesized Pd0 nanoparticles (Pd0NPs) using D. vulgaris biomass as the support and evaluated hydrodehalogenation of CFC-11 catalyzed by the biogenic Pd0NPs. The presence of D. vulgaris biomass stabilized and dispersed 3-6 nm Pd0NPs that were highly active. We documented, for the first time, Pd0-catalyzed simultaneous hydrodechlorination and hydrodefluorination of CFC-11 at ambient conditions (room temperature and 1 atm). More than 70% CFC-11 removal was achieved within 15 h with a catalytic activity of 1.5 L/g-Pd/h, dechlorination was 50%, defluorination was 41%, and selectivity to fully dehalogenated methane was >30%. The reaction pathway had a mixture of parallel and sequential hydrodehalogenation. In particular, hydrodefluorination was favored by higher H2 availability and Pd0:CFC-11 ratio. This study offers a promising strategy for efficient and sustainable treatment of freon-contaminated water.

Reductive Dehalogenation of Herbicides Catalyzed by Pd0NPs in a H2-Based Membrane Catalyst-Film Reactor.

More food production required to feed humans will require intensive use of herbicides to protect against weeds. The widespread application and persistence of herbicides pose environmental risks for nontarget species. Elemental-palladium nanoparticles (Pd0NPs) are known to catalyze reductive dehalogenation of halogenated organic pollutants. In this study, the reductive conversion of 2,4-dichlorophenoxyacetic acid (2,4-D) was evaluated in a H2-based membrane catalyst-film reactor (H2-MCfR), in which Pd0NPs were in situ-synthesized as the catalyst film and used to activate H2 on the surface of H2-delivery membranes. Batch kinetic experiments showed that 99% of 2,4-D was removed and converted to phenoxyacetic acid (POA) within 90 min with a Pd0 surface loading of 20 mg Pd/m2, achieving a catalyst specific activity of 6.6 ± 0.5 L/g-Pd-min. Continuous operation of the H2-MCfR loaded with 20 mg Pd/m2 sustained >99% removal of 50 µM 2,4-D for 20 days. A higher Pd0 surface loading, 1030 mg Pd/m2, also enabled hydrosaturation and hydrolysis of POA to cyclohexanone and glycolic acid. Density functional theory identified the reaction mechanisms and pathways, which involved reductive hydrodechlorination, hydrosaturation, and hydrolysis. Molecular electrostatic potential calculations and Fukui indices suggested that reductive dehalogenation could increase the bioavailability of herbicides. Furthermore, three other halogenated herbicides─atrazine, dicamba, and bromoxynil─were reductively dehalogenated in the H2-MCfR. This study documents a promising method for the removal and detoxification of halogenated herbicides in aqueous environments.

ECG Classification Based on Wasserstein Scalar Curvature.

Electrocardiograms (ECG) analysis is one of the most important ways to diagnose heart disease. This paper proposes an efficient ECG classification method based on Wasserstein scalar curvature to comprehend the connection between heart disease and the mathematical characteristics of ECG. The newly proposed method converts an ECG into a point cloud on the family of Gaussian distribution, where the pathological characteristics of ECG will be extracted by the Wasserstein geometric structure of the statistical manifold. Technically, this paper defines the histogram dispersion of Wasserstein scalar curvature, which can accurately describe the divergence between different heart diseases. By combining medical experience with mathematical ideas from geometry and data science, this paper provides a feasible algorithm for the new method, and the theoretical analysis of the algorithm is carried out. Digital experiments on the classical database with large samples show the new algorithm's accuracy and efficiency when dealing with the classification of heart disease.

Para-Chlorophenol (4-CP) Removal by a Palladium-Coated Biofilm: Coupling Catalytic Dechlorination and Microbial Mineralization via Denitrification.

Rapid dechlorination and full mineralization of para-chlorophenol (4-CP), a toxic contaminant, are unfulfilled goals in water treatment. Means to achieve both goals stem from the novel concept of coupling catalysis by palladium nanoparticles (PdNPs) with biodegradation in a biofilm. Here, we demonstrate that a synergistic version of the hydrogen (H2)-based membrane biofilm reactor (MBfR) enabled simultaneous removals of 4-CP and cocontaminating nitrate. In situ generation of PdNPs within the MBfR biofilm led to rapid 4-CP reductive dechlorination, with >90% selectivity to more bioavailable cyclohexanone. Then, the biofilm mineralized the cyclohexanone by utilizing it as a supplementary electron donor to accelerate nitrate reduction. Long-term operation of the Pd-MBfR enriched the microbial community in cyclohexanone degraders within Clostridium, Chryseobacterium, and Brachymonas. In addition, the PdNP played an important role in accelerating nitrite reduction; while NO3- reduction to NO2- was entirely accomplished by bacteria, NO2- reduction to N2 was catalyzed by PdNPs and bacterial reductases. This study documents a promising option for efficient and complete remediation of halogenated organics and nitrate by the combined action of PdNP and bacterial catalysis.

A Synergistic Platform for Continuous Co-removal of 1,1,1-Trichloroethane, Trichloroethene, and 1,4-Dioxane via Catalytic Dechlorination Followed by Biodegradation.

Groundwater co-contaminated with 1,4-dioxane, 1,1,1-trichloroethane (TCA), and trichloroethene (TCE) is among the most urgent environmental concerns of the U.S. Department of Defense (DoD), U.S. Environmental Protection Agency (EPA), and industries related to chlorinated solvents. Inspired by the pressing need to remove all three contaminants at many sites, we tested a synergistic platform: catalytic reduction of 1,1,1-TCA and TCE to ethane in a H2-based membrane palladium-film reactor (H2-MPfR), followed by aerobic biodegradation of ethane and 1,4-dioxane in an O2-based membrane biofilm reactor (O2-MBfR). During 130 days of continuous operation, 1,1,1-TCA and TCE were 95-98% reductively dechlorinated to ethane in the H2-MPfR, and ethane served as the endogenous primary electron donor for promoting 98.5% aerobic biodegradation of 1,4-dioxane in the O2-MBfR. In addition, the small concentrations of the chlorinated intermediate from the H2-MPfR, dichloroethane (DCA) and monochloroethane (MCA), were fully biodegraded through aerobic biodegradation in the O2-MBfR. The biofilms in the O2-MBfR were enriched in phylotypes closely related to the genera Pseudonocardia known to biodegrade 1,4-dioxane.

H2-Based Membrane Catalyst-Film Reactor (H2-MCfR) Loaded with Palladium for Removing Oxidized Contaminants in Water.

Scalable applications of precious-metal catalysts for water treatment face obstacles in H2-transfer efficiency and catalyst stability during continuous operation. Here, we introduce a H2-based membrane catalyst-film reactor (H2-MCfR), which enables in situ reduction and immobilization of a film of heterogeneous Pd0 catalysts that are stably anchored on the exterior of a nonporous H2-transfer membrane under ambient conditions. In situ immobilization had >95% yield of Pd0 in controllable forms, from isolated single atoms to moderately agglomerated nanoparticles (averaging 3-4 nm). A series of batch tests documented rapid Pd-catalyzed reduction of a wide spectrum of oxyanions (nonmetal and metal) and organics (e.g., industrial raw materials, solvents, refrigerants, and explosives) at room temperature, owing to accurately controlled H2 supply on demand. Reduction kinetics and selectivity were readily controlled through the Pd0 loading on the membranes, H2 pressure, and pH. A 45-day continuous treatment of trichloroethene (TCE)-contaminated water documented removal fluxes up to 120 mg-TCE/m2/d with over 90% selectivity to ethane and minimal (<1.5%) catalyst leaching or deactivation. The results support that the H2-MCfR is a potentially sustainable and reliable catalytic platform for reducing oxidized water contaminants: simple synthesis of an active and versatile catalyst that has long-term stability during continuous operation.

Long-Term Continuous Co-reduction of 1,1,1-Trichloroethane and Trichloroethene over Palladium Nanoparticles Spontaneously Deposited on H2-Transfer Membranes.

1,1,1-Trichloroethane (1,1,1-TCA) and trichloroethene (TCE) are common recalcitrant contaminants that coexist in groundwater. H2-induced reduction over precious-metal catalysts has proven advantageous, but its application to long-term continuous treatment has been limited due to poor H2-transfer efficiency and catalyst loss. Furthermore, catalytic reductions of aqueous 1,1,1-TCA alone or concomitant with TCE catalytic co-reductions are unstudied. Here, we investigated 1,1,1-TCA and TCE co-reduction using palladium nanoparticle (PdNP) catalysts spontaneously deposited on H2-transfer membranes that allow efficient H2 supply on demand in a bubble-free form. The catalytic activities for 1,1,1-TCA and TCE reductions reached 9.9 and 11 L/g-Pd/min, values significantly greater than that reported for other immobilized-PdNP systems. During 90 day continuous operation, removals were up to 95% for 1,1,1-TCA and 99% for TCE. The highest steady-state removal fluxes were 1.5 g/m2/day for 1,1,1-TCA and 1.7 g/m2/day for TCE. The major product was nontoxic ethane (94% selectivity). Only 4% of the originally deposited PdNPs were lost over 90 days of continuous operation. Documenting long-term continuous Pd-catalyzed dechlorination at high surface loading with minimal loss of the catalyst mass or activity, this work expands understanding of and provides a foundation for sustainable catalytic removal of co-existing chlorinated solvents.

Hydrodefluorination of Perfluorooctanoic Acid in the H2-Based Membrane Catalyst-Film Reactor with Platinum Group Metal Nanoparticles: Pathways and Optimal Conditions.

PFAAs (perfluorinated alkyl acids) have become a concern because of their widespread pollution and persistence. A previous study introduced a novel approach for removing and hydrodefluorinating perfluorooctanoic acid (PFOA) using palladium nanoparticles (Pd0NPs) in situ synthesized on H2-gas-transfer membranes. This work focuses on the products, pathways, and optimal catalyst conditions. Kinetic tests tracking PFOA removal, F- release, and hydrodefluorination intermediates documented that PFOA was hydrodefluorinated by a mixture of parallel and stepwise reactions on the Pd0NP surfaces. Slow desorption of defluorination products lowered the catalyst's activity for hydrodefluorination. Of the platinum group metals studied, Pd was overall superior to Pt, Rh, and Ru for hydrodefluorinating PFOA. pH had a strong influence on performance: PFOA was more strongly adsorbed at higher pH, but lower pH promoted defluorination. A membrane catalyst-film reactor (MCfR), containing an optimum loading of 1.2 g/m2 Pd0 for a total Pd amount of 22 mg, removed 3 mg/L PFOA during continuous flow for 90 days, and the removal flux was as high as 4 mg PFOA/m2/d at a steady state. The EPA health advisory level (70 ng/L) also was achieved over the 90 days with the influent PFOA at an environmentally relevant concentration of 500 ng/L. The results document a sustainable catalytic method for the detoxification of PFOA-contaminated water.

Adsorption and Reductive Defluorination of Perfluorooctanoic Acid over Palladium Nanoparticles.

Per- and polyfluoroalkyl substances (PFASs) comprise a group of widespread and recalcitrant contaminants that are attracting increasing concern due to their persistence and adverse health effects. This study evaluated removal of one of the most prevalent PFAS, perfluorooctanoic acid (PFOA), in H2-based membrane catalyst-film reactors (H2-MCfRs) coated with palladium nanoparticles (Pd0NPs). Batch tests documented that Pd0NPs catalyzed hydrodefluorination of PFOA to partially fluorinated and nonfluorinated octanoic acids; the first-order rate constant for PFOA removal was 0.030 h-1, and a maximum defluorination rate was 16 µM/h in our bench-scale MCfR. Continuous-flow tests achieved stable long-term depletion of PFOA to below the EPA health advisory level (70 ng/L) for up to 70 days without catalyst loss or deactivation. Two distinct mechanisms for Pd0-based PFOA removal were identified based on insights from experimental results and density functional theory (DFT) calculations: (1) nonreactive chemisorption of PFOA in a perpendicular orientation on empty metallic surface sites and (2) reactive defluorination promoted by physiosorption of PFOA in a parallel orientation above surface sites populated with activated hydrogen atoms (Hads*). Pd0-based catalytic reduction chemistry and continuous-flow treatment may be broadly applicable to the ambient-temperature destruction of other PFAS compounds.

Geometric Characteristics of the Wasserstein Metric on SPD(n) and Its Applications on Data Processing.

The Wasserstein distance, especially among symmetric positive-definite matrices, has broad and deep influences on the development of artificial intelligence (AI) and other branches of computer science. In this paper, by involving the Wasserstein metric on SPD(n), we obtain computationally feasible expressions for some geometric quantities, including geodesics, exponential maps, the Riemannian connection, Jacobi fields and curvatures, particularly the scalar curvature. Furthermore, we discuss the behavior of geodesics and prove that the manifold is globally geodesic convex. Finally, we design algorithms for point cloud denoising and edge detecting of a polluted image based on the Wasserstein curvature on SPD(n). The experimental results show the efficiency and robustness of our curvature-based methods.

The Nature and Oxidative Reactivity of Urban Magnetic Nanoparticle Dust Provide New Insights into Potential Neurotoxicity Studies.

The recent discovery of magnetic nanoparticles (NPs) in human brain tissue has raised concerns regarding their source and neurotoxicity. As previous studies have suggested that magnetite in urban dust may be the source, we collected urban magnetic dust and thoroughly characterized the nature of ambient urban magnetic dust particles prior to investigating their neurotoxic potential. In addition to magnetite, magnetic dust contained an abundance (∼40%) of elemental iron (Fe0). The coexistence of magnetite and elemental iron was found in magnetic dust particles of inhalable (<10 µm) and nanoscale (<200 nm) size ranges with these particles small enough to enter the human brain via the respiratory tract and olfactory bulbs. The magnetic dust also contained nonferrous water-soluble metals (particularly Cu) that can induce formation of reactive oxygen species (ROS). Previous studies used engineered pure-magnetite for in vitro ROS studies. However, while magnetite was present in all magnetic dust particles collected, engineered pure-magnetite was relatively unreactive and contributed minimally to the generation of ROS. We fill a critical knowledge gap between exposure to heterogeneous ambient iron-particles and in vitro experiments with engineered versus ambient, incidental iron-bearing nanoscale minerals. Our work points to the need to further investigate the presence and properties of magnetic NPs in respirable dust with respect to their potential role in neurodegeneration.

Accurate O2 delivery enabled benzene biodegradation through aerobic activation followed by denitrification-coupled mineralization.

Although benzene can be biodegraded when dissolved oxygen is sufficient, delivering oxygen is energy intensive and can lead to air stripping the benzene. Anaerobes can biodegrade benzene by using electron acceptors other than O2 , and this may reduce costs and exposure risks; the drawback is a remarkably slower growth rate. We evaluated a two-step strategy that involved O2 -dependent benzene activation and cleavage followed by intermediate oxidation coupled to NO3- respiration. We employed a membrane biofilm reactor (MBfR) featuring nonporous hollow fibers as the means to deliver O2 directly to a biofilm at an accurately controlled rate. Benzene was mineralized aerobically when the O2 -supply rate was more than sufficient for mineralization. As the O2 -supply capacity was systematically lowered, O2 respiration was gradually replaced by NO3- respiration. When the maximum O2 -supply capacity was only 20% of the demand for benzene mineralization, O2 was used almost exclusively for benzene activation and cleavage, while respiration was almost only by denitrification. Analyses of microbial community structure and predicted metagenomic function reveal that Burkholderiales was dominant and probably utilized monooxygenase activation, with subsequent mineralization coupled to denitrification; strict anaerobes capable of carboxylative activation were not detected. These results open the door for a promising treatment strategy that simultaneously ameliorates technical and economic challenges of aeration and slow kinetics of anaerobic activation of aromatics.

Complete perchlorate reduction using methane as the sole electron donor and carbon source.

Using a CH4-based membrane biofilm reactor (MBfR), we studied perchlorate (ClO4(-)) reduction by a biofilm performing anaerobic methane oxidation coupled to denitrification (ANMO-D). We focused on the effects of nitrate (NO3(-)) and nitrite (NO2(-)) surface loadings on ClO4(-) reduction and on the biofilm community's mechanism for ClO4(-) reduction. The ANMO-D biofilm reduced up to 5 mg/L of ClO4(-) to a nondetectable level using CH4 as the only electron donor and carbon source when CH4 delivery was not limiting; NO3(-) was completely reduced as well when its surface loading was ≤ 0.32 g N/m(2)-d. When CH4 delivery was limiting, NO3(-) inhibited ClO4(-) reduction by competing for the scarce electron donor. NO2(-) inhibited ClO4(-) reduction when its surface loading was ≥ 0.10 g N/m(2)-d, probably because of cellular toxicity. Although Archaea were present through all stages, Bacteria dominated the ClO4(-)-reducing ANMO-D biofilm, and gene copies of the particulate methane mono-oxygenase (pMMO) correlated to the increase of respiratory gene copies. These pieces of evidence support that ClO4(-) reduction by the MBfR biofilm involved chlorite (ClO2(-)) dismutation to generate the O2 needed as a cosubstrate for the mono-oxygenation of CH4.

3D Molybdenum Disulfide Nanospheres Loaded with Metformin to Enhance SCPP Scaffolds for Bone Regeneration.

Conventional strontium-doped calcium polyphosphate (SCPP) ceramics have attracted a lot of attention due to good cytocompatibility and controlled degradation. However, their poor mechanical strength, brittleness, and difficulty in eliminating unavoidable postoperative inflammation and bacterial infections in practical applications limit their further clinical application. In this study, carboxylated molybdenum disulfide nanospheres (MoS2-COOH) were first prepared via a one-step hydrothermal method. The optimal doping concentration of MoS2-COOH was then incorporated into SCPP to overcome its poor mechanical strength. To further enhance the anti-inflammatory properties of scaffolds, metformin (MET) was loaded onto MoS2-COOH through covalent bond cross-linking (MoS2-MET). Then MoS2-MET was doped into SCPP (SCPP/MoS2-MET) according to the previously obtained concentration, resulting in the controlled and sustained release of MET from the SCPP/MoS2-MET scaffolds for 21 days in vitro. The SCPP/MoS2-MET scaffolds were shown to have good biological activity in vitro to promote stem cell proliferation and the potential to promote mineralization in vitro. It also showed good osteoimmunomodulatory activity could reduce the expression of proinflammatory factors and effectively induce the differentiation of BMSCs under inflammatory conditions, upregulating the expression of relevant osteoblastic cytokines. In addition, SCPP/MoS2-MET scaffolds could effectively inhibit Staphylococcus aureus and Escherichia coli. In vivo experiments also demonstrated better osteogenic potential of SCPP/MoS2-MET scaffolds compared with the other scaffold-samples. Thus, the introduction of carboxylated molybdenum disulfide nanospheres is a promising approach to improve the properties of SCPP and may provide a new modification strategy for inert ceramic scaffolds and the construction of multifunctional composite scaffolds for bone tissue engineering.