Design of BDD-TiO2 hybrid electrode with P-N function for photoelectroatalytic degradation of organic contaminants

P-N hybrid electrode of boron-doped diamond (BDD) and TiO2 were designed and fabricated via selective deposition of TiO2 onto BDD electrode. This hybrid electrode exhibit high photoelectrocatalytic activities toward degradation of acid orange II (AOII) and 2, 4-dichloropheonl (2,4-DCP) due to the P-N effect and high electrocatalytic and photocatalytic activities of BDD electrode and TiO2 particles. The structures of TiO2 and BDD were confirmed by Raman spectra analysis. Atom force microscopy and scanning electron microscopy showed that the TiO2 deposits consist of adherent nanomicro-sized particles, scattered on the BDD substrate. AOII and 2,4-DCP in a solution can be efficiently degraded at the hybrid electrode in the photoelectrocatalysis (PEC) process. Effect of applied bias potentials and solution pH values on AOII and 2,4-DCP degradation were investigated. In the electro-oxidation process, some intermediates such as phenols were detected and they accumulated with the reaction evolution based on the analysis of UV-vis and GC-MS variation. By contrast, phenols intermediates will be degraded with the reaction evolution in the photoelectrocatalysis process. And, organic aromatic and aliphatic carboxylic acids were detected. Furthermore, different degradation mechanism of AOII and 2,4-DCP in the electro-oxidation, photocatalysis, and photoelectrocatalysis is proposed.     

High-temperature adsorption of carbon dioxide on mixed oxides derived from hydrotalcite-like compounds

Various XnY(3-n)Al-hydrotalcite-like compounds (HTlcs) were synthesized by the constant pH coprecipitation method with the (X2+ + Y2+)/Al3+ molar ratio fixed at 3.0. Well-mixed oxides Xn,Y(3-n)AlO were derived from corresponding HTlcs precursors upon calcination. Physicochemical characterization with X-ray diffraction analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and the Brunauer-Emmett-Teller equation indicates that the derived oxides are of either periclase or spinel phase, with an interparticle pore diameter of 9.6-15.4 nm. These oxides generally show a high CO2 adsorption capability at 350 degrees C. For example, CaCoAlO captures 1.39 mmol/g of CO2 (i.e., 6.12 wt %) from a gas mixture (8% CO2 in N2) at 350 degrees C and 1 atm in a fixed-bed reactor within 20 min. All other mixed oxides adsorb 0.87-1.28 mmol/g (3.83-5.63 wt %) of CO2. Therefore, these mixed oxides are potential cost-effective CO2 sorbents for environmental remediation. In addition, the CO2 adsorption behavior is well-described with the deactivation model. The species of CO2 formed on the sorbents are various carbonates, as revealed by in situ IR spectra as well as TGA.     

高效液相色谱-串联质谱法测定樱桃番茄中四种季铵类农药

建立了4种季铵类农药(矮壮素、燕麦枯、敌草快和缩节胺)的高效液相色谱-串联质谱(LC-MS/MS)检测方法。样品用75%乙腈-水溶液提取,高速离心后取上清液过尼龙滤膜,用亲水柱分离,以含0.1%甲酸的水:乙腈=25:75(V:V)作为流动相,在正离子多反应监测(MRM)模式下进行测定。4种季铵类农药的线性范围为0.5～100ng/mL,线性相关系数在0.9982～0.9996范围内,方法检出限为0.005mg/kg,可以满足国际限量的要求。在0.04、0.08、0.16mg/kg添加浓度下,4种季铵类农药的回收率为91.4%～106.3%,相对标准偏差(RSD)小于15%。本方法可用于樱桃番茄样品中4种季铵类农药的测定。     

Parallel color-coding

We present new parallelization and memory-reducing strategies for the graph-theoretic color-coding approximation technique, with applications to biological network analysis. Color-coding is a technique that gives fixed parameter tractable algorithms for several well-known NP-hard optimization problems. In this work, by efficiently parallelizing steps in color-coding, we create two new biological protein interaction network analysis tools: Fascia for subgraph counting and motif finding and FastPath for signaling pathway detection. We demonstrate considerable speedup over prior work, and the optimizations introduced in this paper can also be used for other problems where color-coding is applicable.     

Evaluation of anaerobic co-digestion of spent brewery grains and an azo dye

Anaerobic batch biodegradation of spent brewery grains (SBG) was investigated in the presence of co-substrates and a monoazo dye (Acid Orange 7 – AO7) under mesophilic and thermophilic regimes. The highest values for the yield coefficient of biogas (STP) on substrate (Y_bs) were obtained under mesophilic conditions (0.381–0.516 Lbiogas/g COD_removed and 0.147 to 0.475 L_biogas/g COD_removed for mesophilic and thermophilic regimes, respectively). A stimulation of the degradation of SBG associated with microbial growth was observed in the presence of co-substrates (glucose and acetate). Supplemented co-substrates also lowered the residual COD leading to an increase in the COD removal efficiency, particularly under thermophilic regime (from 41% to 70%). Although biogas yield (Y_bs) indicates a decrease in the presence of the dye, suggesting that it has inhibitory effects, the overall COD removal was not significantly altered. An increase of colour removal was observed when the temperature of the operation was increased (87 ± 2% and 93 ± 1% for mesophilic and thermophilic reactors, respectively), which could be explained by both faster adsorption and biotic reductive cleavage of azo dye bond mechanisms. These results indicate that raw SBG is more prone to biodegradation under an anaerobic mesophilic regime; hence its bio-energetic valorisation is possible.     

Selection,characterization and application of aptamers targeted to Aflatoxin B2

Aflatoxins are naturally occurring mycotoxins that can contaminate foodstuffs and consequently affect human health. In this study, the systematic evolution of ligands by exponential enrichment (SELEX) technology was used to effectively screen DNA aptamers that recognize Aflatoxin B2 (AFB2) with high affinity and specificity. AFB2 was first combined with magnetic nanoparticles, which served as carriers, and then incubated with a library of single-stranded DNA (ssDNA). The entire selection process included incubation, separation, elution, PCR amplification and single chain preparation. The selection conditions were optimized. After 10 rounds of selection, 30 aptamer sequences were obtained and enriched. Homological analysis in combination with structural analysis as well as the affinity and specificity experiments revealed that aptamer sequence 17 showed the best affinity and specificity toward AFB2. The dissociation constants value for aptamer sequence 17 was 9.83 nM. And the specificity experiment results showed the binding between AFB2 aptamer with five other toxins was very week (did not exceed 18% compared to AFB2). The selected AFB2 aptamer was used to construct a fluorescent biosensor. The assay showed a wide linear range, with the AFB2 concentration ranging from 100 ng/L to 1800 ng/L and a detection limit of 50 ng/L. Additionally, the spiked recovery experiment of AFB2 in peanut oil sample exhibited a recovery ratio between 94.0% and 101.6% which showed good accuracy of the proposed aptamer-based bioassay.     

Promoting effect of microwave irradiation on CeO_2-TiO_2 catalyst for selective catalytic reduction of NO by NH_3

In this work we prepared several CeO₂-TiO₂ catalysts for the NH₃-SCR reactionusing co-precipitation with assistance of microwave irradiation. The catalytic NH₃-SCR activities over CeO₂-TiO₂ catalysts at low temperatures are largely enhanced by the treatment of microwave irradiation, the operation temperature window is also broadened. For better understanding the promotion mechanism, the catalyst prepared by conventional co-precipitation with and without microwave irradiation treatment was characterized with H₂-TPR, NH₃-TPD, XPS, XRD and BET. Microwave irradiation treatment accelerates the crystallite rate of CeO₂-TiO₂ catalysts, and greatly enlarges their surface area by adjusting their microstructures. The resistance to SO₂ and H₂O is also improved via regulating the hierarchical pore structure by the microwave irradiation. Microwave irradiation treatment can also improve the redox property and increase the acid sites over the catalyst surfaces. The result of in situ DRIFTS suggests that the microwave irradiation treatment generates more Brønsted acid sites on CeO₂-TiO₂-2 h catalyst, helpful in SCR reactions. XPS results show that after microwave irradiation on the CeO₂-TiO₂ catalysts, the surface demonstrates an elevated concentration of chemisorbed oxygen, consequently leading to better oxidation of NO to NO₂. Additionally, the molar ratio of Ce³⁺/Ce⁴⁺ has been elevated after being treated by microwave irradiation, a vital factor in enhancing the NH₃-SCR activities.     

A Derivative-Free Hybrid Optimization Model for Short-Term Operation of a Multi-Objective Reservoir System Under Uncertainty

Short-term operation of a multi-objective reservoir system under inflow uncertainty has been receiving increasing attention, however, major challenges for the optimization of this system still remain due to the multiple and often conflicting objectives, highly nonlinear constraints and uncertain parameters in which derivative information may not be directly available. Population-based optimization methods do not rely on derivatives while generally have a slow convergence. This study presents a hybrid optimization model for short-term operation of multi-objective reservoirs under uncertainty that is derivative free and has a relatively fast convergence. The model incorporates a local improvement method called Mesh Adaptive Direct Search (MADS) into a population-based method NSGA-II and has no requirement for differentiability, convexity and continuity of the optimization problem. The operation of a multi-objective and multi-reservoir system on the Columbia River under inflow uncertainty is used as a case study. Overall, the hybrid model outperforms optimization models based on either the NSGA-II only or the MADS only. The model is intended for conditions where derivative information of the optimization problem is unavailable, which could have a wide array of applications in water resources systems.     

Enzyme-Triggered Transforming of Assembly Peptide-Modified Magnetic Resonance-Tuned Probe for Highly Sensitive Imaging of Bacterial Infection In Vivo

Confirming bacterial infection at an early stage and distinguishing between sterile inflammation and bacterial infection is still highly needed for efficient treatment. Here, in situ highly sensitive magnetic resonance imaging (MRI) bacterial infection in vivo based on a peptide-modified magnetic resonance tuning (MRET) probe (MPD-1) that responds to matrix metallopeptidase 2 (MMP-2) highly expressed in bacteria-infected microenvironments is achieved. MPD-1 is an assembly of magnetic nanoparticle (MNP) bearing with gadolinium ion (Gd³⁺) modified MMP-2-cleavable self-assembled peptide (P₁) and bacteria-targeting peptide (P), and it shows T₂-weighted signal due to the assemble of MNP and MRET ON phenomenon between MNP assembly and Gd³⁺. Once MPD-1 accumulates at the bacterially infected site, P₁ included in MPD-1 is cleaved explicitly by MMP-2, which triggers the T₂ contrast agent of MPD-1 to disassemble into the monomer of MNP, leading the recovery of T₁-weighted signal. Simultaneously, Gd³⁺ detaches from MNP, further enhancing the T₁-weighted signal due to MRET OFF. The sensitive MRI of Staphylococcus aureus (low to 10⁴ CFU) at the myositis site and accurate differentiation between sterile inflammation and bacterial infection based on the proposed MPD-1 probe suggests that this novel probe would be a promising candidate for efficiently detecting bacterial infection in vivo.     

Efficient destruction of pathogenic bacteria with AgBr/TiO2 under visible light irradiation

The photocatalytic inactivation of pathogenic bacteria in water was investigated systematically with AgBr/TiO₂ under visible light (λ > 420 nm) irradiation. The catalyst was found to be highly effective for the killing of Escherichia coli, a Gram-negative bacterium, and Staphylococcus aureus, a Gram-positive bacterium. The decomposition of the cell wall and cell membrane was directly observed by TEM and further confirmed by K⁺ leakage from the inactivated bacteria. A possible cell damage mechanism by visible light-driven AgBr/TiO₂ is proposed. In addition, the effects of pH, inorganic ions on bacterial photocatalytic inactivation were investigated. The electrostatic force interaction of the bacteria–catalyst is crucial for the efficiency of disinfection. Moreover, AgBr/TiO₂ supported on porous nickel showed much higher bactericidal activity than fixed P25 TiO₂ under visible or near UV light irradiation.