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Due to the complexity of the structure and surface property of metal oxide catalysts, hydrophobization of metal oxide catalysts is a great challenge. The hydrophobization strategy and effects of hy...

Functionalized catalysts with multiple active centers have been studied in direct conversion of ethanol to butadiene (ETB). However, it is still a considerable challenge to control the synergistic effect of multiple active centers. Here, we report that a series of ZnMg/SBA-15-based catalysts were synthesized for the direct ETB process. The non-polar solvent n-hexane is utilized to improve the synergistic effects of ZnO, MgO and SBA-15. The characterization results demonstrate that the ZnMg/SBA-15-hexane catalyst, prepared from n-hexane solvent, can increase dehydrogenation activity and promote synergistic catalysis. The direct ETB performance reveals that it exhibits an excellent selectivity of 70% towards the butadiene product. Further, our in situ DRIFTS analysis indicates that aldol condensation and the MPV reaction are the rate-determining steps of the direct ETB process. The present work offers a simple strategy to optimize synergies of multiple active centers.

As one of the Holy Grail reactions in C1 chemistry, direct selective oxidation of methane to methanol under mild and non-harsh conditions remains a big challenge. Hydroperoxide (H2O2), as a primary oxidant, applied widely in the low-temperature direct selective conversion of methane to methanol. Moreover, the hydrogen and oxygen mixture gas achieves better reaction activity and higher methanol selectivity than H2O2 when using palladium-gold (Pd-Au) bimetallic nanoparticles as the catalyst. In this paper, we studied the key roles of the physical and chemical characteristics of Pd-Au nanoparticles in this direct selective oxidation reaction with hydrogen and oxygen as the oxidant at 50 °C. Au metal shows an indispensable role in direct methane to methanol process in this study. High methanol productivity and selectivity are achieved when Au of 0.5–2.5% is added into the carbon nanotubes (CNTs) supported Pd catalyst. Moreover, the loading amount of Pd-Au nanoparticles also affect the methane activation ability and the methanol selectivity obviously. Much more active and stable Pd-Au nanoparticles are generated in CNTs supported 2.5% Pd-2.5% Au nanoparticles catalyst than those in lower metal content catalysts. In addition, the Pd bivalent state is proved to be the most active content in the Pd-Au nanoparticles catalyst, achieving much higher methanol selectivity and productivity when compared to Pd metallic state. For further clarifying the physical and chemical characteristics of catalysts, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Hydrogen-Temperature-programmed reduction (H2-TPR), and CO pulse adsorption measurement (CO-PULSE) analysis methods are also measured.

Flexible humidity sensors play important roles in wearable devices and consuming electronics which provide a convenient way between digital and physical worlds. This work presents an easy fabricated method for flexible humidity sensors all based on carbon material including electrodes and functional layers. The interdigital electrodes are made by direct laser writing on commercial Kapton tapes and the transferring to flexible Polydimethylsiloxane (PDMS) substrates. The humidity sensing material is reduced graphene oxide (rGO) in nanometer thickness by electrospray. The rGO flakes covered the micro-size laser induced graphite (LIG), forming rGO-graphite balls, dramatically increase surface areas to interact with water molecules. The results show high precision sensitivity and fast response time for adsorption (0.9 s) and desorption (4.5 s). This method provides a novel method for fabricating cost-effective flexible humidity sensors.

A conductometric immunoassay protocol was designed for the sensitive detection of a liver cancer biomarker, alpha-fetoprotein (AFP), in biological fluids by using enzyme-conjugated nanometer-sized enzyme-doped silica beads. Initially, urease molecules were doped into nanosilica particles by using the reverse micelle method. Thereafter, arginase-labeled anti-AFP antibodies were covalently conjugated onto the surface of the synthesized nanoparticles. The immunoreaction was carried out in a monoclonal anti-AFP capture antibody-coated microplate with a sandwich-type assay format by using bienzyme-functionalized silica nanobeads as the recognition elements. Upon l-arginine introduction, the substrate was cleaved into urea and l-ornithine on the basis of the arginase enzymatic reaction, and the as-produced urea was then decomposed into ammonia (NH4+) and bicarbonate (HCO3-) ions by the doped urease, thus causing the variation in the local conductivity of the detection solution on an interdigitated conductometric transducer. Under optimal conditions, the developed immunosensing system exhibited good conductometric responses toward target AFP within a dynamic linear range of 0.01-100 ng mL-1 at a relatively low detection limit of 4.8 pg mL-1 based on the 3sB criterion. Importantly, good reproducibility, high specificity and acceptable method accuracy were acquired for the analysis of human serum specimens in liver cancer patients.

Facile preparation of highly efficient iron-based catalysts is vital to improve the performance of Fischer-Tropsch synthesis (FTS), a sustainable process for converting non-petroleum carbon resources to valuable hydrocarbons. In this work, a convenient preparation for nitrogen-regulated graphene supported iron nanoparticles, with the assistant of microwave treatment, was developed. Thereinto, the nitrogen-containing groups in graphene support were introduced by NH3·H2O treatment. By comparison with ordinary calcination, microwave treatment could significantly shorten the heating time to few seconds, and promote the reduction of iron species. The existence of a small number of nitrogen-containing groups could effectively anchor iron species, and improve the dispersion of iron species. Meanwhile, the duration length of NH3·H2O treatment time could regulate the content of N configuration (pyridinic-N and pyrrolic-N). The size of supported iron species from 120 nm to 10 nm could be well controlled via increasing microwave time from 0 to 14 s. For N-regulated graphene supported iron catalysts, evenly dispersed small particles of iron species, improved surface reduction behavior and reasonable N configuration all promoted FTS. Under relevant industrial conditions (320 °C, 2.0 MPa, 5 g h mol−1), the optimized 15%Fe/AG(12 h)-W(10) catalyst achieved CO conversion as high as 97.2% and C5+ selectivity of 40.0% while maintaining a mild CO2 selectivity (28.2%). The superior preparation and catalytic performance disclosed that the catalyst could be one of ideal candidates for industrial iron-based FTS catalysts in future.

We have successfully demonstrated a stretchable gas sensor with enhanced sensitivity to hydrogen based on crumpled graphene structures. Compared with the state-of-art technologies, three distinctive advancements have been achieved: (1) enhanced sensitivity to hydrogen based on the crumpled graphene at room temperature; (2) a model on the enhanced sensing mechanism on the crumpled graphene surface; and (3) stretchable gas sensor utilizing crumpled graphene with up to 200% stretchability. As such, the proposed sensing scheme and results could open up a new class of graphene-based, stretchable gas sensing systems for environmental and biological monitoring.

In order to study the mechanism of high temperature environment’s influence on the mechanical properties and interparticle interactions of ceramic polymer materials for fire-resistant cables, the typical models of three ceramic polyolefin Formulations were established according to the distribution proportion of each material. With the assistance of molecular simulation software, molecular dynamics simulation was carried out. The results show that with the increase of temperature, the intermolecular interaction weakens, the mechanical modulus decreases, and the FFV increases. The Formulation with the most significant intermolecular interaction at high temperature, the one with the largest mechanical modulus at the same temperature and the one with the slowest increase of FFV with temperature’s increase is the mixture system of ceramic ethylene butene copolymer and 28% EVA. The simulation results can provide reference for the selection of polyolefin ceramic materials for fire resistant cables.

Molybdenum-zeolite catalysts always suffer from severe carbon deposition and rapid deactivation in the methane dehydroaromatization (MDA) process. Herein, we present a strategy that controls spatial distance between Mo species and HMCM-22 zeolite over Mo/HMCM-22 catalysts, to inhibit the severe carbon deposition. Our characterization analyses demonstrate that the Mo/HMCM-22 catalysts possess the same active components, but the spatial distance plays a key role in determining product selectivity in the MDA process. The MDA performance reveals that Mo/HMCM-22-MM (mechanical milling) catalyst, with a medium spatial distance between Mo species and HMCM-22 zeolite, significantly inhibits carbon deposition and produces high selectivity to benzene. This work shows that spatial distance between molybdenum and zeolite is an important property for suppressing carbon deposition and improving benzene selectivity in MDA process.

Herein, a bovine serum albumin-stabilized gold clusters-MnO2 nanocomposite (BSA@AuNCs–MnO2) was constructed. Manganese dioxide (MnO2) was generated in situ on the gold clusters (BSA@AuNCs) based on the redox reaction between bovine serum albumin (BSA) and potassium permanganate (KMnO4). The fluorescence of BSA@AuNCs can be quenched by the in-situ grown MnO2, which has strong light absorption ability. It is worth noting that the quenched fluorescence of the BSA@AuNCs can be restored in the presence of glutathione (GSH), and MnO2 was reduced to Mn2+ in return. Encouragingly, 1 μM GSH can cause a detectable fluorescence change. This sensitivity is comparable to other nanomaterials based fluorescent probes. Furthermore, this nanocomposite has obvious superiorities, such as good uniformity, simple preparation and mild reaction. The nanocomposite also has good stability and specificity, which can be further used for visualizing of intracellular GSH.

Volume 8, no. 2, e00157-17, 2017, [https://doi.org/10.1128/mBio.00157-17][1]. One source of funding for our study was not properly acknowledged. The acknowledgment section of the manuscript should read: We regret to note that Mark A. Wainberg passed away in April 2017. Therefore, the corresponding

The performance and mechanisms of a microbial induced calcite precipitation (MICP)-assisted mature fine tailings (MFT) consolidation method was assessed. Mature fine tailings samples of 35 wt% and 60 wt% were treated with MICP by ureolysis. The undrained shear strength of treated MFT was measured to evaluate the effects of MICP on MFT consolidation. To investigate the surface interaction mechanisms involved in the process, the size and shape of MFT particles were observed using scanning electron microscopy. The results showed that ureolysis-driven MICP can accelerate raw MFT consolidation, leaving compact sludge with significantly enhanced shear strength within 24 h of the experiment.

Human immunodeficiency virus (HIV) infection persists despite decades of active antiretroviral therapy (ART), effectively preventing viral eradication. Treatment decreases plasma viral RNA, but viral DNA persists, mostly integrated within the genome of nucleated blood cells. Viral DNA blood levels correlate with comorbidities and the rapidity of viral rebound following treatment interruption. To date, no intervention aiming at decreasing HIV DNA levels below those attained through ART has been successful. This includes use of some integrase inhibitors either as part of ART or in treatment intensification studies. We have argued that using the integrase inhibitor dolutegravir (DTG) in similar studies may yield better results, but this remains to be studied. In treatment-experienced individuals, the most frequent substitution associated with failure with dolutegravir is R263K in integrase. R263K decreases integration both in cell-free and tissue culture assays. We investigated here how integrated DNA levels evolve over time during prolonged infections with R263K viruses. To investigate a potential defect in reverse transcription with R263K, the levels of reverse transcripts were measured by quantitative PCR. We measured HIV type 1 (HIV-1) integration in Jurkat cells over the course of 4-week infections using Alu-mediated quantitative PCR. The results show that R263K did not decrease reverse transcription. Prolonged infections with R263K mutant viruses led to less HIV-1 integrated DNA over time compared to wild-type viruses. These tissue culture results help to explain the absence of the R263K substitution in most individuals experiencing failure with DTG and support studies aiming at longitudinally measuring the levels of integrated DNA in individuals treated with this drug., IMPORTANCE Antiretroviral treatment decreases plasma viral RNA, but HIV DNA persists for decades within infected cells. Studies of nonhuman primates have suggested that reducing retroviral DNA levels might represent a path to eradication. The integrase inhibitor dolutegravir is less susceptible than any other anti-HIV drug to the emergence of resistance in treatment-naive individuals. In treatment-experienced individuals, in contrast, rare cases of treatment failure were commonly associated with emergence of an R263K integrase substitution that confers low-level resistance to dolutegravir. It is unclear why this substitution is not more common in individuals experiencing failure with dolutegravir. We report here that R263K progressively diminishes the levels of integrated HIV-1 DNA in tissue culture over multiple cycles of infection. Our results help to explain aspects of the clinical efficacy of dolutegravir and suggest that this drug may be able to reduce HIV DNA levels within infected individuals compared to other drugs.

Bacterial initial adhesion to inert surfaces in aquatic environments is highly dependent on the surface properties of the substratum, which can be altered significantly by the formation of conditioning films. In this study, the impact of conditioning films formed with extracellular polymeric substances (EPS) on bacterial adhesion was investigated. Adhesion of wild type Pseudomonas aeruginosa PAO1 to slides coated with model EPS components (alginate, humic substances, and bovine serum albumin (BSA)) was examined. Surface roughness of conditioning film coated slides was evaluated by atomic force microscopy (AFM), and its effect on the bacterial initial adhesion was not significant. X-ray photoelectron spectroscopy (XPS) studies were performed to determine the elemental surface compositions of bacterial cells and substrates. Results showed that bacterial adhesion to bare slides and slides coated with alginate and humic substances increased as ionic strength increased. Conversely, BSA coating enhanced bacterial adhesion at low ionic strength but hindered adhesion at higher ionic strength. It was concluded that forces other than hydrophobic and electrostatic interactions were involved in controlling bacterial adhesion to BSA coated surfaces. A steric model for polymer brushes that considers the combined influence of steric effects and DLVO interaction forces was shown to adequately describe the observed bacterial adhesion behaviors.

Municipal stormwater retention ponds are a means of managing stormwater in urban settings. Numerous contaminants collect in stormwater retention ponds, creating problems such as odor. Because of the complex and variable nature of stormwater quality, a comprehensive study involving both a field study and a laboratory study were accomplished. These two components used a multidisciplinary approach, focused on both water chemistry and microbiological methods to analyze the existing conditions that encourage sulfide production. The field study compared two stormwater retention ponds in terms of water quality and sediment microbial communities in Edmonton, Canada to determine methods to reduce sulfate levels, which are believed to stimulate generation of the toxic hydrogen sulfide. The field study comparison was followed by laboratory studies focused on methods of suppressing sulfide production. Nitrate amendments were found to be effective in suppressing sulfate production; however, the addition of a c...

Shangwan coal is a low-rank coal from inner Mongolia. Shangwan coal particles show electronegativity in the slurry, because there are many oxygenated functional groups, such as the carboxyl group, hydroxyl group, and carbonyl group on the surface and in the core of the particles. Besides, because these functional groups are all hydrophilic, Shangwan coal shows strong water-retaining capacity. Hence, coal–water slurries (CWSs) made from Shangwan coal contain little free water, and their coal concentration is low. In this paper, we used four different chemicals to coat the surface of Shangwan coal and investigate the corresponding effects on slurry preparation. Tests of contact angle indicate that the physical characteristics of coal particles are adjusted, because surfactants cover the coal surface and the hydrophobicity of the coal surface is increased. Measuring the ζ potential confirms that the absolute value of the ζ potential of modified coal is higher than that of unmodified coal, for instance, about...

The R263K substitution in integrase has been selected in tissue culture with dolutegravir (DTG) and has been reported for several treatment-experienced individuals receiving DTG as part of salvage therapy. The R263K substitution seems to be incompatible with the presence of common resistance mutations associated with raltegravir (RAL), a different integrase strand transfer inhibitor (INSTI). T66I is a substitution that is common in individuals who have developed resistance against a different INSTI termed elvitegravir (EVG), but it is not known whether these two mutations might be compatible in the context of resistance against DTG or what impact the combination of these substitutions might have on resistance against INSTIs. E138K is a common secondary substitution observed with various primary resistance substitutions in RAL- and EVG-treated individuals. Viral infectivity, replicative capacity, and resistance against INSTIs were measured in cell-based assays. Strand transfer and 3′ processing activities were measured biochemically. The combination of the R263K and T66I substitutions decreased HIV-1 infectivity, replicative capacity, and strand transfer activity. The addition of the E138K substitution partially compensated for these deficits and resulted in high levels of resistance against EVG but not against DTG or RAL. These findings suggest that the presence of the T66I substitution will not compromise the activity of DTG and may also help to prevent the additional generation of the R263K mutation. Our observations support the use of DTG in second-line therapy for individuals who experience treatment failure with EVG due to the T66I substitution.IMPORTANCEThe integrase strand transfer inhibitors (INSTIs) elvitegravir and dolutegravir are newly developed inhibitors against human immunodeficiency virus type 1 (HIV-1). HIV drug-resistant mutations in integrase that can arise in individuals treated with elvitegravir commonly include the T66I substitution, whereas R263K is a signature resistance substitution against dolutegravir. In order to determine how different combinations of integrase resistance mutations can influence the outcome of therapy, we report here the effects of the T66I, E138K, and R263K substitutions, alone and in combination, on viral replicative capacity and resistance to integrase inhibitors. Our results show that the addition of R263K to the T66I substitution diminishes viral replicative capacity and strand transfer activity while not compromising susceptibility to dolutegravir. This supports the use of dolutegravir in second-line therapy for patients failing elvitegravir therapy who harbor the T66I resistance substitution.

Objectives Dolutegravir is an integrase strand-transfer inhibitor that has shown unprecedented robustness against the emergence of HIV drug-resistant strains in treatment-naive individuals. The R263K substitution in integrase was identified through culture selection as a resistance-associated substitution for dolutegravir and was recently detected in two treatment-experienced participants in the SAILING clinical trial, who experienced dolutegravir-based treatment failure, one of whom was infected by a subtype C virus. The objective of this study was to characterize the R263K substitution in HIV-1 subtype C integrase. Design and methods We used cell-free strand transfer assays and tissue culture experiments to characterize the R263K substitution in HIV-1 subtype C integrase in comparison with subtype B. Results Cell-free biochemical assays showed that the R263K substitution diminished subtype C integrase strand-transfer activity by decreasing the affinity of integrase for target DNA. Similarly, both viral infectiousness and replication capacity were reduced by the R263K substitution in tissue culture. Decrease in enzyme activity and viral infectiousness exceeded 35 and 50%, respectively - significantly more than in HIV-1 subtype B. R263K in HIV-1 subtype C also conferred low levels of resistance against dolutegravir and high levels of cross-resistance against elvitegravir, but not raltegravir. Conclusions The R263K substitution is more deleterious to integrase strand-transfer activity and viral infectiousness in HIV-1 subtype C than in subtype B. Our results suggest that cross-resistance may prevent treatment-experienced individuals who are experiencing treatment failure with dolutegravir from being subsequently treated with elvitegravir.