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A tunable tight-binding (TB) Hamiltonian, which can be tuned continuously by applying the strains, is proposed based on the two tight-binding Hamiltonian models used to describle the pristine and compressed black phosphorus (BP). This tunable TB Hamiltonian should be of fundamental significance in two aspects: i) A general tunable TB Hamiltonian making it possible to study the BP more conveniently and deeply; ii) An extension of the study of the strain effect from the monolayer phosphorene to the multilayer phosphorene and even the bulk BP in the presence of both the in-plane and out-of-plane strains. Furthermore, based on the tunable TB Hamiltonian we can find the strain-induced quasi-Dirac cone, and clearly disclose how the strains affect the formation of the quasi-Dirac cone. Then we investigate the Landau levels (LLs) of BP under different magnetic fields, uncovering the linear, square-root, or complex dependence of the LLs on the LL number or the magnetic field. Moreover, the double-step and triple-step transitions of the LLs are found to be induced by the strains for the BP in the in-plane and out-of-plane magnetic fields. This research successfully incorporates the out-of-plane strain effect into the tunable TB Hamiltonian, enabling the comprehensive investigation of the strain-correlated effect in BP.

The inhibition of tetracycline on anaerobic digestion of synthetic swine wastewater was examined with a semi-continuous operation for 103 days at a dosage ranging 2–8 mg/L. COD concentrations, VFA compositions in effluents and methane production were measured. The negative effects of tetracycline on the four individual steps of anaerobic digestion and its toxicity on anaerobic microorganisms were also evaluated. Results showed that continuous addition of 8 mg/L tetracycline in the bioreactor resulted in 73.28% reduction of daily methane production and made anaerobic digestion upset. Besides, methanogenesis was particularly inhibited compared to other three steps and the corresponding enzyme activities decreased by 66%. Furthermore, the polysaccharide contents in EPS increased after exposure to tetracycline, which could inhibit direct connections among microorganism. At last, long-term exposure to tetracycline inhibit anaerobic microbial activities and caused liberation of lactate dehydrogenase. The results would provide novel insights for anaerobic digestion of swine wastewater.

Herein, carbon sphere (CS-T) were successfully prepared by pyrolyzation melamine formaldehyde resin. And then different transition metals (Fe, Co, Ni) were doped on carbon sphere (CS-M-900). The scanning electron microscopes and elemental mappings prove that the transition metal particles are uniformly doped on the carbon sphere. Meanwhile, the X-ray photoelectron spectrum prove that the transition metals are zero-valence. Furthermore, the electrochemical testings showed the CS-Co-900 had more positive onset potential (0.93 V), half-wave potential (0.84 V), and peak potential (0.81 V). Furthermore, the CS-Co-900 had lower charge transfer resistance (44 Ω) and smaller Tafel slope (65 mV/dec). Most importantly, the oxygen reduction reaction on the CS-Co-900 turned out to be a four electron procedure with excellent methanol tolerance. The improved electrochemical properties towards oxygen reduction reactions of carbon sphere via cobalt doping suggested a design strategy towards future high-performance electrochemical devices.

Anaerobic fermentation is a clean production process for recycling of many agricultural and industrial wastes. During anaerobic fermentation, the existence of various inhibitors often leads to low efficiency or even failure of anaerobic digesters. 5-hydroxymethylfurfural (HMF) is such an inhibitor which can be produced in the pretreatment of biomass for subsequent anaerobic digestion. This paper provides a review of various production methods of HMF and its effects on hydrogen production, methane production and ethanol production through fermentation. The conversion and removal of HMF were summarized from the aspects of biomass pretreatment, non-biological treatment and biological treatment. This article aims to provide new ideas and methods for reducing the inhibition effect of HMF on anaerobic fermentation of biomass and restoring the performance of the anaerobic fermentation.

5-Hydroxymethylfurfural (HMF) is a high value-added chemical, the starting material for the production of a large number of platform chemicals, and an inhibitor of anaerobic digestion. The selection of microorganisms that can metabolize HMF or have high tolerance to HMF is rapidly arousing scientific interest. For selecting suitable microorganisms from aerobic sludge and exploring the effects of HMF on aerobic digestion, the removal capability, activated sludge characteristics, and microbial community structure of activated sludge treating digested swine wastewater in the presence of HMF were studied. Results showed that HMF deteriorated the removal performance of activated sludge. Removal rates of chemical oxygen demand (COD), total phosphorus (TP) and ammonium (NH4+-N) were reduced from 95.7%, 84.6% and 80.0% to 46.5%, 77.6% and 21.0%, respectively. Besides, HMF also increased EPS content which reduced the settleability and dewatering capacity of activated sludge. Moreover, HMF inhibited dehydrogenase (DHA) activity in activated sludge and increased superoxide dismutase (SOD) activity. Meanwhile, the functions of microorganisms had changed, extracellular structure increased, carbohydrates and lipids transport and metabolism decreased, and energy production and conversion were inhibited. Microbial community analysis illustrated HMF adversely affects Enterobacteriaceae and streptococcaceae, while Bacillaceae, Rhodocyclaceae and Nitrospira better tolerate HMF.

Anaerobic digestion is widely used for the treatment of wastewater for its low costs and bioenergy production, but the performances of anaerobic digestion often need improving in practical applications. The addition of conductive materials could lead to direct interspecies electron transfer (DIET) among the anaerobic microorganisms, and consequently enhance the efficiencies of anaerobic digestion. In this paper, the effects of DIET via conductive materials on chemical organic demand (COD) removal, volatile fatty acid (VFA) consumption and methane production were reviewed. The reports on the increase of conductive microorganisms due to the addition of conductive materials were discussed. Results regarding activities of microorganisms and morphology and properties of sludge were described and commented, and future research needs were also proposed which included better understanding of the roles of DIET in each step of anaerobic digestion, mechanisms of metabolism of pollutants in DIET-established systems and inhibition of excessive dosage of conductive materials.

Based on the tight-binding Hamiltonian approach, we demonstrate that the electromechanical field effect transistors (FETs) can be realized by using the multilayer phosphorene nanoribbons (PNRs). The synergistic combination of the electric field and the external strains can establish the on–off switching since the electric field can shift or split the energy band, and the mechanical strains can widen or narrow the band widths. This kind of multilayer PNR FETs, much solider than the monolayer PNR one and more easily biased by different electric fields, has more transport channels consequently leading to the higher on–off current ratio or the higher sensitivity to the electric fields. Meanwhile, the strain-induced band-flattening will be beneficial for improving the flexibility in designing the electromechanical FETs. In addition, such electromechanical FETs can act as strain-controlled FETs or mechanical detectors for detecting the strains, indicating their potential applications in nano- and micro-electromechanical fields.

Using the tight-binding Hamiltonian approach, we comparatively investigate the energy spectrums of triangular zigzag phosphorene quantum dots (PQDs) and rings (PQRs), as well as their potential applications. In comparison with the outer edge states in the PQD, new extra inner edge states can be produced in the PQR by its internal hole. A transition from the uncoupled to coupled edge states can be induced by decreasing the width between the outer and inner edges of the PQR. Also, the edge states in PQD/PQR are all anisotropically localized in one side, rather than three sides as in triangular graphene quantum dots (QDs) and rings (QRs). Furthermore, the PQD/PQR energy levels can be anisotropically manipulated by the external electric fields and strains, clearly demonstrating their potential applications in field effect transistors or electromechanical devices. In the meanwhile, we also consider the electron probability distributions corresponding to the different energy levels, clearly exposing the characteristics of the PQD/PQR energy levels. The comparison between the asymmetrical triangular PQDs/PQRs and the symmetrical triangular QDs/QRs in graphene should be instructive for understanding the similar triangular QDs/QRs in other two-dimensional layered materials, as well as other types of QDs/QRs of different shapes.

Selenium is one of the most attractive nutrient elements for antioxidant, anticancer and immunomodulatory effects, which is obtained from the agricultural food and environment. Herein, a gold nanocages/fluorinated graphene (AuNCs/FG) nanocomposite modified glassy carbon electrode (GCE) was fabricated for the electrochemical determination of selenium by square wave anodic stripping voltammetry. Under the optimal parameters, a wide linear relationship between peak current of selenium on AuNCs/FG/GCE and selenium concentration was observed between 0.002−5.0 mg/L. The method exhibited a low detection limit of 0.27 μg/L. The proposed method was applied successfully for the determination of selenium in agricultural food (tea, rapeseed sprouts, peanut) and environmental (tap water and lake water) samples. The results showed that the average levels of selenium were 0.04−0.27 mg/kg and not detectable, in agricultural food and water, respectively. Therefore, this method has great potential for the monitor of selenium in food and environmental samples.

boron carbide–cerium boride porous composites are prepared by hot pressed sintering, and mechanical properties and microstructure of boron carbide–cerium boride porous composites were tested. The results show that Flexibility strength of B4C-CeB6 porous composites is greatly improved compared with that of monolithic porous boron carbide. B4C react with CeO2 to completely form CeB6 in porous composites. CeB6 particles in B4C grain boundary are produced by in-situ reaction. The presence of CeB6 reinforcing particles could also suppress growth of B4C grains which normally leads to improved strength.

B4C-CeB6 porous composites are prepared by hot pressed sintering between 1900°C and 2000°C, and mechanical properties and phase composition of B4C-CeB6 porous composites were tested. The results show that the porous rate of B4C-CeB6 porous composites ranges between 30%-48% at sintering temperate 1900°C-2000°C. Porous rate of B4C-CeB6 porous composites is decreased with temperature be increased. Flexibility strength of B4C-CeB6 porous composites is greatly improved compared with that of monolithic porous boron carbide. B4C react with CeO2 to completely form CeB6 in porous composites.

A series of new 1-(carbamoylmethyl)-2-aryl-3,1-benzoxazines were prepared in moderate to good yields by BF3·OEt2-catalyzed reactions of aromatic aldehydes with 2-(N-substituted carbamoylmethylamino)benzyl alcohols. The structures of the target compounds were confirmed by IR, 1H-NMR, 13C-NMR, and elemental analyses. The fungicidal activities of the target compounds against plant fungi were preliminarily evaluated, and some of them exhibited good activity.

Using the Hartree Fock (RHF) method, we study the most reactive carbon atoms in the polycyclic aromatic hydrocarbons (PAHs). In order to identify the most reactive carbon atoms, the Mulliken charges and the Mayers bond orders were calculated as the criterion. The results demonstrate that the most reactive carbon atoms appear at the locations of the outer C in the inner benzene rings for cata-condensed PAHs, while for peri-condensed PAHs they are the outer C in the outer benzene rings。

To drive the application of surface-enhanced Raman spectroscopy (SERS) mapping in ex vivo diagnostic imaging and non-biological material characterization, we have designed a robust and accurate multiplex spectral fitting method using an alternating minimization algorithm to extract individual constituent Raman spectra with very small overall fitting error (as low as 2%). For each mixed Raman signal, constituent spectra and mixture coefficients were estimated jointly based on reference spectra that were measured in the lab. Our method is based on a Poisson model to reflect the photon counting nature of Raman signals and includes the nonlinear noise in the measured data, making our method robust against data containing relatively large random noise. In our method, we minimized a cost function consisting of two terms: (1) the overall fitting error between the measured and modeled spectra and (2) the sum of the individual error between each reference spectrum and its corresponding constituent. This method inherently guarantees that the estimates will approach the global minimum with monotonic convergence. The accuracy of our method was validated by applying it to a SERS spectral fitting problem and comparing our results to those from existing methods. Copyright © 2013 John Wiley & Sons, Ltd.

Using the tight-binding Hamiltonian approach, we theoretically study the electronic and optical properties of a triangular phosphorene quantum dot (PQD) including one normal zigzag edge and two skewed armchair edges (ZAA-PQD). It is shown that the energy spectrum can be classified into the filled band (FB), the zero-energy band (ZB), and the unfilled band (UB). Numerical calculations of the FB, ZB, and UB probability distributions show that the FB and the UB correspond to the bulk states, while the ZB corresponds to the edge states, which appear on all of the three edges of the ZAA-PQD sharply different from the other PQDs. We also find that the strains and the electric fields can affect the energy levels inhomogeneously. Then the optical properties of the ZAA-PQD are investigated. There appear some strong low-energy optical absorption peaks indicating its sensitive low-energy optical response that is absent in other PQDs. Moreover, the strains and the electric fields can make inhomogeneous influences on the optical spectrum of the ZAA-PQD. This work may provide a useful reference for designing the electrical, mechanical, and optical PQD devices.

In order to resolve the discharge problem of the polymer-flooding produced water (PFPW) in crude oil extraction, the PFPW was treated by a four-grade and four-segment (four GS) electrodialysis reversal(EDR) set-up. The testing results show that the treated PFPW has two kinds, one is the diluted treated PFPW, the total dissolved solids (TDS) of the diluted treated PFPW is less than the original PFPW, the diluted treated PFPW is feasible for confecting polymer solution; another one is the concentrated treated PFPW, the TDS of the concentrated treated PFPW exceeds the original PFPW, the concentrated treated PFPW is feasible for replacing the PFPW as the injecting water in the water-flooding process for high permeability layer. This treatment technology can not only decrease environment pollution resulted by the PFPW discharge, but also achieve closed-circuit of the water resource during crude oil extraction by using polymer flooding technology.

Supercritical water oxidation (SCWO) is a recent development aiming at the destruction of organic pollutants. The present paper focuses on the process simulation of oxidation of oil-field sludge in supercritical water with simple experimental equipment. In the supercritical combustion reactions, the removal of crude oil sludge is affected by the factors of residence time, temperature, pressure, and the initial process parameters such as crude oil content. The results obtained show that supercritical water oxidation can effectively remove the crude oil of the oilfield sludge, the removal efficiency of crude oil comes to 95%. The important factors are residence time, reaction temperature, reaction pressure and finite change of oil-field sludge in quantity. The removal efficiency of crude oil of the oil-field sludge increases with increasing the reaction temperature, residence time and reaction pressure.