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In this work, a ternary Ti 3 C 2 /TiO 2 /SrTiO 3 composite with heterogeneous network structure was prepared by two-step in situ hydrothermal synthesis method, which mainly involved the growth of TiO 2 nanosheets and fibrous SrTiO 3 sequentially on the Ti 3 C 2 substrate using the Ti source inherent in Ti 3 C 2 as the reaction site. The Ti 3 C 2 /TiO 2 /SrTiO 3 heterojunction exhibited enhanced photocatalytic hydrogen evolution activity. When the doping amount of SrTiO 3 was 5 wt%, the hydrogen evolution rate of 5MTS under full solar irradiation reached 14322.6 μmol·g−1·h−1, which was 10.6 times the rate of the Ti 3 C 2 /TiO 2 composite without modified SrTiO 3. Meanwhile, the 5MTS composites showed good stability in the photocatalytic hydrogen evolution cycle test. The enhanced activity and recyclability are mainly attributed to the strong light absorption ability, fast separation of photogenerated electron-hole pairs, and abundant catalytic active sites. In addition, the synthesis method utilizing an intrinsic Ti source also enhances the interfacial contact between Ti 3 C 2 , TiO 2 , and SrTiO 3. This study provides an effective reference for the construction of perovskite-based or Ti 3 C 2 co-catalyzed heterostructures and their application for the conversion of solar power to hydrogen energy. [Display omitted] • The Ti 3 C 2 /TiO 2 /SrTiO 3 ternary photocatalyst was prepared by in situ hydrothermal growth without additional Ti source. • The heterojunction originated from the interfaces promoted the photogenerated carrier migration and hydrogen evolution. • The composite exhibited an excellent hydrogen evolution rate of 14322.6 μmol·g−1·h−1 under full solar irradiation. [ABSTRACT FROM AUTHOR]

The activated sludge method is widely used for the treatment of phenol-containing wastewater, which gives rise to the problem of toxic residual sludge accumulation. Indole-3-acetic acid (IAA), a typical phytohormone, facilitates the microalgal resistance to toxic inhibition while promoting biomass accumulation. In this study, Chlorococcum humicola (C. humicola) was cultured in toxic sludge extract and different concentrations of IAA were used to regulate its physiological properties and enrichment of high value-added products. Ultimately, proteomics analysis was used to reveal the response mechanism of C. humicola to exogenous IAA. The results showed that the IAA concentration of 5 × 10−6 mol/L (M) was most beneficial for C. humicola to cope with the toxic stress in the sludge extract medium, to promote the activity of rubisco enzyme, to enhance the efficiency of photosynthesis, and, finally, to accumulate protein as a percentage of specific dry weight 1.57 times more than that of the control group. Exogenous IAA altered the relative abundance of various amino acids in C. humicola cells, and proteomic analyses showed that exogenous IAA stimulated the algal cells to produce more indole-3-glycerol phosphate (IGP), indole, and serine by up-regulating the enzymes. These precursors are converted to tryptophan under the regulation of tryptophan synthase (A0A383V983), and tryptophan can be metabolized to endogenous IAA to promote the growth of C. humicola. These findings have important implications for the treatment of toxic residual sludge while enriching for high-value amino acids. [Display omitted] • Appropriate IAA addition allowed C. humicola to thrive in the sludge extract medium. • Appropriate concentrations of IAA promote protein accumulation in algal cell. • Exogenous IAA can change the proportion of various amino acids in algal cell. • Up-regulation of A0A383V983 promoted tryptophan enrichment. • Exogenous IAA stimulated endogenous IAA synthesis. [ABSTRACT FROM AUTHOR]

In the present work, we report a high activity Ti 3 C 2 MXene nanosheet/TiO 2 (Ti 3 C 2 /TiO 2) composite photocatalyst synthesized by a solvent-thermal method using tetrabutyl titanate (Ti(OBu) 4) as Ti source and HF as assistant. The Ti 3 C 2 /TiO 2 composites were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV–Vis spectroscopy (UV–vis), fluorescence spectrometer (PL) and N 2 adsorption-desorption. The photocatalytic performance of the Ti 3 C 2 /TiO 2 composites was explored for the degradation of rhodamine B (RhB) under visible light irradiation. The results showed that more highly-active (001) crystal surfaces of TiO 2 were exposed in the Ti 3 C 2 /TiO 2 composites assisted by HF. The composite consisted of TiO 2 microspheres and multilayer Ti 3 C 2 exhibited optimal photocatalytic performance with relatively large specific surface area, large photocurrent and much lower impedances as compared to commercial TiO 2 (P25) and pure TiO 2. The optimized sample exhibited a degradation rate of 93.7% in 60 min, which was 20.5-fold higher than that of P25. The addition of the Ti 3 C 2 effectively increased the lifetimes of the Ti 3 C 2 /TiO 2 composites and suppressed the recombination of the electron-hole pairs. The density functional theory (DFT) calculations also revealed that the photogenerated electrons in the composites flowed from TiO 2 to Ti 3 C 2. The Schottky barrier at the TiO 2 –Ti 3 C 2 interfaces effectively inhibited the electronic reflow to TiO 2. The as-developed new Ti 3 C 2 -based complex with high photocatalytic activity under visible light irradiation might have effective and feasible application in the treatment of dye-containing wastewater. [ABSTRACT FROM AUTHOR]

In this paper, carbon nanotubes (CNTs) modified TiO 2 /C/Co@C composites (TiO 2 /C/Co@C(CNTs)) with good electromagnetic (EM) wave properties were synthesized originated from ZIF-67/MXene composites supplemented with external carbon source melamine by in situ synthesis and high temperature pyrolysis. The effect of the melamine content on the microstructure, EM parameters, and the microwave absorption (MWA) properties of the TiO 2 /C/Co@C(CNTs) composites was investigated. The results showed that the in-situ grown CNTs were organically connected to the pyrolyzed ZIF-67/MXene derivatives to form a hybrid network structure. The composites achieve the minimum reflection loss (RL min) value of −47.52 dB at a thickness of 1.5 mm, the effective absorption bandwidth (EAB) of 5.06 GHz at 1.8 mm with the RL min value of −41.35 dB, and the RL min value of −52.43 dB at 6.18 GHz. The excellent EM wave attenuation ability of the TiO 2 /C/Co@C(CNTs) composites covers nearly the entire frequency band of 2–18 GHz with the RL min value almost less than −30 dB in the thickness of 1.5–5.0 mm. The unique microstructure, dielectric-magnetic synergistic effect, and multiple interfacial polarization optimize the impedance matching. This word proposes a promising new strategy for constructing highly efficient MOF-derived and MXene-based microwave absorbers. [Display omitted] • TiO 2 /C/Co@C(CNTs) composites were fabricated by in situ synthesis and pyrolysis. • The composites exhibited excellent MWA performance with RL min of −47.52 dB at 1.5 mm. • The multiple polarization was promoted by compatible Co–C, TiO 2 –C and C–C interfaces. [ABSTRACT FROM AUTHOR]

Abstract Novel zinc oxide (ZnO) array/polyurethane (PU) nanocomposite coatings on the stainless steel substrates was fabricated via a simple process. ZnO arrays were prepared using zinc nitrate and hexamethylenetetramine by a seed growth method, followed by the spinning of PU. The morphologies, structure, wettability, mechanical performance and infrared radiation properties were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, surface contact angle, nanoindentation and infrared radiation tests. The corrosion properties of the ZnO array/PU nanocomposite coating were evaluated by the electrochemical tests. The results showed that the ZnO arrays were hexagonal wurtzite and well dispersed in the composite coatings, resulting in slight increase in hydrophilicity. The mechanical properties of the coatings were improved with increased content of the ZnO arrays. The as-prepared ZnO array/PU nanocomposite coatings exhibited excellent corrosion resistance. The infrared radiation performance was observed to be slightly improved as well. It is believed that the unique organic/inorganic nanocomposite coating offers the effective strategy and potential applications for designing the functional coatings of good corrosion resistance and mechanical properties in various polymer systems. Graphical abstract Unlabelled Image Highlights • ·ZnO array/PU nanocomposite coatings on stainless steel substrates were fabricated. • ·Inorganic skeleton of ZnO arrays was well dispersed into PU matrix. • ·The content and density of ZnO arrays could be effectively adjusted. • ·The coatings showed improved corrosion resistance and mechanical properties. [ABSTRACT FROM AUTHOR]

Several per- and polyfluoroalkyl substances (PFAS) have been measured in U.S. National Health and Nutrition Examination Survey (NHANES) participants 12 years of age and older since 1999-2000, but PFAS data using NHANES individual samples among children younger than 12 years do not exist. To obtain the first nationally representative PFAS exposure data in U.S. children, we quantified serum concentrations of 14 PFAS including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), in a nationally representative subsample of 639 3-11year old participants in NHANES 2013-2014. We used on-line solid-phase extraction coupled to isotope dilution-high performance liquid chromatography-tandem mass spectrometry; limits of detection were 0.1ng/mL for all analytes. We calculated geometric mean concentrations, determined weighted Pearson correlations, and used linear regression to evaluate associations of sex, age (3-5 vs 6-11 years), race/ethnicity (Hispanic vs non-Hispanic), household income, and body mass index with concentrations of PFAS detected in more than 60% of participants. We detected PFOS, PFOA, PFHxS, and PFNA in all children at concentrations similar to those of NHANES 2013-2014 adolescents and adults, suggesting prevalent exposure to these PFAS or their precursors among U.S. 3-11year old children, most of whom were born after the phase out of PFOS in the United States in 2002. PFAS concentration differences by sex, race/ethnicity, and age suggest lifestyle differences that may impact exposure, and highlight the importance of identifying exposure sources and of studying the environmental fate and transport of PFAS. [ABSTRACT FROM AUTHOR]

Background Industrial discharges of perfluorooctanoic acid (PFOA) to the Ohio River, contaminating water systems near Parkersburg, WV, were previously associated with nearby residents' serum PFOA concentrations above US general population medians. Ohio River PFOA concentrations downstream are elevated, suggesting Mid-Ohio River Valley residents are exposed through drinking water. Objectives Quantify PFOA and 10 other per- and polyfluoroalkyl substances (PFAS) in Mid-Ohio River Valley resident sera collected between 1991 and 2013 and determine whether the Ohio River and Ohio River Aquifer are exposure sources. Methods We measured eleven PFAS in 1608 sera from 931 participants. Serum PFOA concentration and water source associations were assessed using linear mixed-effects models. We estimated between-sample serum PFOA using one-compartment pharmacokinetics for participants with multiple samples. Results In serum samples collected as early as 1991, PFOA (median = 7.6 ng/mL) was detected in 99.9% of sera; 47% had concentrations greater than US population 95th percentiles. Five other PFAS were detected in greater than 82% of samples; median other PFAS concentrations were similar to the US general population. Serum PFOA was significantly associated with water source, sampling year, age at sampling, tap water consumption, pregnancy, gravidity and breastfeeding. Serum PFOA was 40–60% lower with granular activated carbon (GAC) use. Repeated measurements and pharmacokinetics suggest serum PFOA peaked 2000–2006 for participants using water without GAC treatment; where GAC was used, serum PFOA concentrations decreased from 1991 to 2012. Conclusions Mid-Ohio River Valley residents appear to have PFOA, but not other PFAS, serum concentrations above US population levels. Drinking water from the Ohio River and Ohio River Aquifer, primarily contaminated by industrial discharges 209–666 km upstream, is likely the primary exposure source. GAC treatment of drinking water mitigates, but does not eliminate, PFOA exposure. [ABSTRACT FROM AUTHOR]

Background: General population human biomonitoring programs such as the National Health and Nutrition Examination Survey (NHANES) in the United States suggest that chemical exposures are common. Exposures during childhood may affect health later in life, but biomonitoring data in NHANES among pre-school aged children are limited.Methods: A convenience group of 122 3-5year old American boys and girls were recruited in 2013 for a pilot study to assess the feasibility of collecting urine from young children and analyzing it for select chemical exposure biomarkers for future NHANES. Children were primarily Hispanic (64.8%); the remainder was divided between non-Hispanic black, and non-Hispanic white and "other." We measured 52 urinary biomarkers: 13 phthalates and one non-phthalate plasticizer, five phenols and four parabens, 10 polycyclic aromatic hydrocarbons (PAHs), and 19 pesticides. For each biomarker, we calculated descriptive statistics. We also calculated the number of biomarkers detected within each child, and performed principal components analysis (PCA).Results: NHANES staff obtained permission to attempt collection of 60mL urine from 3 to 5year olds who participated in the 2013 NHANES health examination; 83% of children successfully provided the target volume. We detected 24 individual biomarkers of pesticides, phenols and parabens, phthalates/non-phthalate plasticizers, and PAHs in 95-100% of children. The median number of biomarkers detected was 37: nine pesticides, five phenols and parabens, 13 phthalates and non-phthalate plasticizers, and 10 PAHs. Biomarkers concentrations appear to be similar to national estimates among 6-11year old children from previous NHANES. PCA suggested high within-class correlations among biomarkers.Conclusions: These young children successfully adhered to the collection protocol and produced enough urine for the quantification of environmental biomarkers currently being measured in NHANES participants 6 years of age and older. Using the same analytical methods employed for the analysis of samples collected from older NHANES participants, in this sample of pre-school aged children we detected multiple chemicals including plasticizers, combustion products, personal-care product chemicals, and pesticides. Starting with NHANES 2015-2016, the NHANES biomonitoring program will include urinary biomarkers for 3-5year old children to provide exposure data to select chemicals at the national level among this age group. [ABSTRACT FROM AUTHOR]