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N-doped carbon fibers (NCFs) were in situ prepared by Camellia sinensis branches waste through hydrothermal carbonization with urea/ZnCl

Risk management is an important aspect of financial research because correlations among financial data are essential in evaluating portfolio risk. Among various correlations, spatiotemporal correlations involve economic entity attributes and are interrelated in space and time. Such correlations have therefore drawn increasing attention in financial risk management. However, classical correlation measurements are typically based on either time series correlations or spatial dependence; they cannot be directly applied to financial data with spatiotemporal correlations. The spatiotemporal correlation coefficient model with adaptive weight proposed in this paper can (1) address the absolute quantity, dynamic quantity, and dynamic development of financial data and (2) be used for risk grading, financial risk evaluation, and portfolio management. To verify the validity and superiority of this model, cluster analysis results and portfolio performance are compared with a classical model with time series correlation or spatial correlation, respectively. Empirical findings show that the proposed coefficient is highly effective and convenient compared to others. Overall, our method provides a highly efficient financial risk management method with valuable implications for investors and financial institutions.

Semi-bent functions play an important role in symmetric ciphers and sequence designs. So far, there are few studies related to the construction of vectorial semi-bent functions even though lots of work has been done on single-output semi-bent functions. In this paper, three classes of balanced vectorial semi-bent functions are presented with varying cryptographic properties. The classes denoted $${{\mathcal {D}}}{{\mathcal {C}}}$$ and $${{\mathcal {D}}}{{\mathcal {S}}}$$ are constructed using disjoint codes and disjoint spectra functions, respectively. The former class has a useful provable property that its component functions do not admit linear structures. It is shown that the number of output bits of the constructed n-variable $${{\mathcal {D}}}{{\mathcal {C}}}$$ and $${{\mathcal {D}}}{{\mathcal {S}}}$$ vectorial functions can respectively reach $$(n+1)/2$$ and n/3. In addition, a construction method of semi-bent functions from $${\mathbb {F}}_2^{3n} \rightarrow {\mathbb {F}}_2^n$$ by using almost bent (AB) functions on $${\mathbb {F}}_2^n$$ is given.

L-valine is an essential branched-chain amino acid that cannot be synthesized by the human body and has a wide range of applications in food, medicine and feed. Market demand has stimulated people's interest in the industrial production of L-valine. At present, the mutagenized or engineered Corynebacterium glutamicum is an effective microbial cell factory for producing L-valine. Because the biosynthetic pathway and metabolic network of L-valine are intricate and strictly regulated by a variety of key enzymes and genes, highly targeted metabolic engineering can no longer meet the demand for efficient biosynthesis of L-valine. In recent years, the development of omics technology has promoted the upgrading of traditional metabolic engineering to systematic metabolic engineering. This whole-cell-scale transformation strategy has become a productive method for developing L-valine producing strains. This review provides an overview of the biosynthesis and regulation mechanism of L-valine, and summarizes the current metabolic engineering techniques and strategies for constructing L-valine high-producing strains. Finally, the opinion of constructing a cell factory for efficiently biosynthesizing L-valine was proposed.

In this paper, we study the bounded traveling wave solutions for the Boussinesq equation with dissipative term by using the theory of planar dynamical systems, and reveal the relationships between the behaviors of bounded traveling wave solutions and the dissipation coefficient. The bell profile solitary wave solution and kink profile solitary wave solution can be obtained according to the undermined coefficients method. Meanwhile, the approximate oscillatory damped solutions can be obtained. Furthermore, the global error estimation of the approximate oscillatory damped solutions is given by establishing the integral equation which reflects the relationships between approximate and exact oscillatory damped solutions.

NiCo2O4 nanoneedles were grown on reduced graphene oxide (rGO) by a hydrothermal method. Physical characterization and electrochemical tests were performed on the composites. The NiCo2O4/rGO composites possessed a high capacitance of 1757 F g−1 (1 A g−1). The composites possessed 97.3% of initial capacity after 2500 cycles (10 A g−1). Furthermore, the prepared NiCo2O4/rGO//AC asymmetric supercapacitor obtained a well energy density of 32.38 W h kg−1. After 10000 cycles at 5 A g−1, 90.4% of the capacity was retained. Therefore, the NiCo2O4/rGO nanocomposites appear to be excellent candidates for high performance supercapacitors.

Hydrate flow obstacles encountered during the exploitation of deep-water gas fields has received an increased attention. Based on the variations in the wellbore temperature of a deep-water gas well during the initial restarting period, and considering the interrelationship between the hydrate behavior and heat transfer, a prediction model for hydrate flow obstacle was established by comprehensively considering the hydrate formation, deposition, and decomposition. This model could be used to analyze the hydrate formation and decomposition regions dynamically and depict the evolution of the hydrate plug quantitatively during the restarting period. The computation results demonstrated that the wellbore temperature increased with the restarting time, which caused the hydrate formation region to decrease accordingly. During the initial restart under testing operations, hydrates always formed at low gas production rates in the tubing, which could plug the tubing after a certain restarting time. The risk of hydrate flow obstacle first increased and then decreased with an increase in the restarting production rate. During the initial restart under production operations, hydrates only formed at the initial restarting stage, which ranged from several minutes to more than 10 h. The hydrate flow obstacle risk first increased and then decreased with the restarting time, and no hydrate plugging occurred during the initial restarting period of the entire production process. Finally, the measures for preventing hydrate plugging during the initial restarting period were discussed. This work provides a valuable theoretical reference for preventing hydrate plugging during the initial restarting period of a deep-water gas well.

Unmanned aerial vehicles (UAVs) are prone to losing their targets when tracking moving objectives. A tracking strategy is proposed herein that enables the standoff tracking of a moving target using a vision system, which significantly reduces the occurrence of target loss. The strategy combines the Gimbal Control Algorithm based on Motion Compensation (GCAMC) with the Improved Reference Point Guidance Method (IRPGM). The GCAMC utilizes the attitude of the UAV and the deviation of the target from image center as the feedback. The target can be kept within the field-of-view (FOV) of the camera when the gimbal model is unknown. The IRPGM generates straight or circular paths according to the speed and potition of the target, while the UAV will continuously track the generated trajectory to achieve the objective of target tracking. To validate and demonstrate the tracking performance of the proposed strategy, a closed-loop visual simulation platform was devised and implemented to simulate the process of target tracking. The results of the simulation demonstrate that by using the proposed approach, the UAV can enter the desired trajectory quickly when its initial position and flight direction are arbitrary.

The photocatalysis is a very promising technique to address the serious issues of environmental pollution. Among the common photocatalysts, the graphitic carbon nitride (g-C3N4) is widely used for the photodegradation of organic pollutants due to its proper band structure. To further improve the photocatalytic performance of g-C3N4, a novel composite photocatalyst of Co3O4/PT-C3N4 has been prepared by using a one-pot calcination method, in which cobalt tetroxide (Co3O4) nanoparticles as the cocatalyst are introduced on the surface of rectangular hollow g-C3N4 substrate (PT-Co3O4). As a result, the obtained composite photocatalyst (Co3O4/PT-C3N4) delivers an excellent photodegradation performance for diesel oil under a simulated sunlight, which can improve the separation efficiency of the photo-induced electron–hole pairs. The Co3O4/PT-C3N4 composite photocatalyst exhibits a high degradation efficiency of 96.27% after 2 h of visible light, which is much higher than that of the PT-C3N4 photocatalyst. Moreover, the composite photocatalyst can still maintain a high photodegradation efficiency after 10 cycles, exhibiting an excellent cyclic stability. The photo-induced carriers generated by the Co3O4/PT-C3N4 composite photocatalyst follow the Z-scheme heterojunction transfer mechanism. This work gives a fresh idea for the exploration of new high-performance photocatalyst for the treatment of organic environmental pollutants.

The photocatalysis of graphtic carbon nitride (g-C3N4) material has been widely used for the photocatalytic degradation of organic pollutants. However, g-C3N4 still has some drawbacks, such as the high recombination of photo-induced electron–hole pairs and weak absorption of light irradiation. To further improve the photodegradation performance of g-C3N4, a novel composite photocatalyst (CoO/ PT-C3N4) has been prepared by using a one-pot calcination method, in which cobalt oxide (CoO) as a cocatalyst are introduced on the rectangular hollow substrate of g-C3N4 (PT-C3N4), The CoO/PT-C3N4 composite photocatalyst delivers an excellent photodegradation performance for diesel oil under a simulated sunlight. It exhibits a high degradation efficiency of 95.92% after light irradiation for 2 h, which is much higher than that of pristine PT-C3N4. Free radical capture experiments manifest that the free radical of ·O2− plays a major role for the photodegradation and main active radicals abide by the sequence: ·O2− > ·OH > h+. Moreover, the CoO/PT-C3N4 composite photocatalyst delivers an excellent cyclic stability, which only degrades 8.71% photodegradation efficiency after 10 cycles. The improvement of CoO/PT-C3N4 composite photocatalyst is ascribed to the formation of a heterojunction between CoO and PT-C3N4, which promotes the separation of photo-induced carriers. This work paves a new way for the exploration of photocatalyst for the organic pollutant degradation.

This study investigates the predictability of a fixed uncertainty index (UI) for realized variances (volatility) in the international stock markets from a high-frequency perspective. We construct a composite UI based on the scaled principal component analysis (s-PCA) method and demonstrate that it exhibits significant in- and out-of-sample predictabilities for realized variances in global stock markets. This predictive power is more powerful than those of two commonly employed competing methods, namely, PCA and the partial least squares (PLS) methods. The result is robust in several checks. Further, we explain that s-PCA outperforms other dimension-reduction methods since it can effectively increase the impacts of strong predictors and decrease those of weak factors. The implications of this research are significant for investors who allocate assets globally.

Ni/PANI coaxial nanowire arrays were prepared by electrochemical deposition using porous anodic alumina as a template. The samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction and Fourier transform infrared spectrometer. The morphology results showed that the outer diameter and wall thickness of Ni/PANI coaxial nanowires were about 100 nm and 20 nm respectively and the PANI nanotubes were completely filled with the Ni nanowires. Cyclic voltammetry (C–V) and chronoamperometry (I–t) showed that Ni/PANI coaxial nanowires can be used as good electrode materials for non-enzymatic glucose sensors. The electrode of Ni/PANI coaxial nanowires has high sensitivity (76.8 μA mM−1 cm−2), low detection limit (10 μM) and wide linear range (0–7 mM) (R2 = 0.982), as well as good selectivity and stability.

Differential uniformity of permutation polynomials has been studied intensively in recent years due to the differential cryptanalysis of S-boxes. The boomerang attack is a variant of differential cryptanalysis which combines two differentials for the upper part and the lower part of the block cipher. The boomerang uniformity measures the resistance of block ciphers to the boomerang attack. In this paper, by using the resultant elimination method, we study the boomerang uniformity of normalized permutation polynomials of the low degree over finite fields. As a result, we determine the boomerang uniformity of all normalized permutation polynomials of degree up to six over the finite field $${\mathbb {F}}_{q}$$.

One-dimensional carbon nanotube material decorated by NiCo2O4 nanoparticles has been successfully fabricated by a facile one-pot hydrothermal method together with a sequent annealing treatment. The as-prepared nanoscale CNT-NiCo2O4 composites with network structure manifested an enhanced specific capacitance of 1055A g−1 at a current density of 1 A g−1 and an outstanding cycling performance compared with pure NiCo2O4. When tested at current density of 20 A g−1, excellent capacity retention ratio up to 99.8% can be achieved for the composite electrode after 6500 cycles. The remarkable cycling performance can mainly be attributed to composite unique structure that CNTs present high conductivity together with NiCo2O4 nanoparticle's eminent capacity. Consequently, the ultrahigh specific capacity coupled with admirable cycling stability makes such composite a promising electrode material candidate for supercapacitor in energy storage.

Coastal erosion is widespread under conditions of changing hydrodynamics and diminishing sediment supply, and exposure assessment to erosion hazard has received increasing attention. In this study, we explore the impact of spatial heterogeneity of land use within administrative units on exposure assessment of land use value to erosional hazard. We illustrate land use diversity using the Shannon’s diversity index (SHDI) and consider the distance effect by comparing five different buffer zones according to the distance to the coast (i.e., 0–1 km, 0–2 km, 0–3 km, 0–4 km, 0–5 km). Our results show that coastline change and socio-economic development are responsible for land use heterogeneity within the administrative units. Using a buffer zone of 1-km along the coast as the assessment unit leads to an increase in the number of townships that have high and very high exposure of land use value when compared with the assessment result that is based on the whole township area. Furthermore, the 1-km buffer zone can be divided into subunits if very high SHDI values exist within the administrative boundary. This study demonstrates that heterogeneity in land use identified at a fine spatial scale should be given full consideration in carrying out exposure assessment to hazards in a dynamic deltaic coast.

With the gradual demographic shift toward an aging and obese society, an increasing number of patients are suffering from bone and cartilage injuries. However, conventional therapies are hindered by the defects of materials, failing to adequately stimulate the necessary cellular response to promote sufficient cartilage regeneration, bone remodeling and osseointegration. In recent years, the rapid development of nanomedicine has initiated a revolution in orthopedics, especially in tissue engineering and regenerative medicine, due to their capacity to effectively stimulate cellular responses on a nanoscale with enhanced drug loading efficiency, targeted capability, increased mechanical properties and improved uptake rate, resulting in an improved therapeutic effect. Therefore, a comprehensive review of advancements in nanomedicine for bone and cartilage diseases is timely and beneficial. This review firstly summarized the wide range of existing nanotechnology applications in the medical field. The progressive development of nano delivery systems in nanomedicine, including nanoparticles and biomimetic techniques, which are lacking in the current literature, is further described. More importantly, we also highlighted the research advancements of nanomedicine in bone and cartilage repair using the latest preclinical and clinical examples, and further discussed the research directions of nano-therapies in future clinical practice. Graphical Abstract

The current study aimed to evaluate the clinical practice for hemodynamic tissue signature (HTS) method in IDH genotype prediction in three groups derived from high-grade gliomas. Preoperative MRI examinations of 44 patients with known grade and IDH genotype were assigned into three study groups: glioblastoma multiforme, grade III, and high-grade gliomas. Perfusion parameters were analyzed and were used to automatically draw the four reproducible habitats (high-angiogenic enhancing tumor habitats, low-angiogenic enhancing tumor habitats, infiltrated peripheral edema habitats, vasogenic peripheral edema habitats) related to vascular heterogeneity. These four habitats were then compared between inter-patient with IDH mutation and their wild-type counterparts at these three groups, respectively. The discriminating potential for HTS in assessing IDH mutation status prediction was assessed by ROC curves. Compared with IDH wild type, IDH mutation had significantly decreased relative cerebral blood volume (rCBV) at the high-angiogenic enhancing tumor habitats and low-angiogenic enhancing tumor habitats. ROC analysis revealed that the rCBVs in habitats had great ability to discriminate IDH mutation from their wild type in all groups. In addition, the Kaplan-Meier survival analysis yielded significant differences for the survival times observed from the populations dichotomized by low ( 4.31) rCBV in the low-angiogenic enhancing tumor habitat. The HTS method has been proven to have high prediction capabilities for IDH mutation status in high-grade glioma patients, providing a set of quantifiable habitats associated with tumor vascular heterogeneity. • The HTS method has a high accuracy for molecular stratification prediction for all subsets of HGG. • The HTS method can give IDH mutation–related hemodynamic information of tumor-infiltrated and vasogenic edema. • IDH-relevant rCBV difference in habitats will be a great prognosis factor in HGG.

Hydrogen peroxide (H2O2) is a major reactive oxygen species in unicellular and multicellular organisms, and is produced extracellularly in response to external stresses and internal cues1-4. H2O2 enters cells through aquaporin membrane proteins and covalently modifies cytoplasmic proteins to regulate signalling and cellular processes. However, whether sensors for H2O2 also exist on the cell surface remains unknown. In plant cells, H2O2 triggers an influx of Ca2+ ions, which is thought to be involved in H2O2 sensing and signalling. Here, by using forward genetic screens based on Ca2+ imaging, we isolated hydrogen-peroxide-induced Ca2+ increases (hpca) mutants in Arabidopsis, and identified HPCA1 as a leucine-rich-repeat receptor kinase belonging to a previously uncharacterized subfamily that features two extra pairs of cysteine residues in the extracellular domain. HPCA1 is localized to the plasma membrane and is activated by H2O2 via covalent modification of extracellular cysteine residues, which leads to autophosphorylation of HPCA1. HPCA1 mediates H2O2-induced activation of Ca2+ channels in guard cells and is required for stomatal closure. Our findings help to identify how the perception of extracellular H2O2 is integrated with responses to various external stresses and internal cues in plants, and have implications for the design of crops with enhanced fitness.

In this paper, we focus on studying the asymptotic stability of the monotone decreasing kink profile solitary wave solutions for the generalized KdV-Burgers equation. We obtain the estimate of the first-order and second-order derivatives for monotone decreasing kink profile solitary wave solutions, and overcome the difficulties caused by high-order nonlinear terms in the generalized KdV-Burgers equation in the estimate by using L2 energy estimating method and Young inequality. We prove that the monotone decreasing kink profile solitary wave solutions are asymptotically stable in H1. Moreover, we obtain the decay rate of the perturbation ψ in the sense of L2 and L∞ norm, respectively, which are (1 + t) −1/2 and (1 + t) −1/4 by using Gargliado-Nirenberg inequality.

The implement of sustainable hydrogen production is a prerequisite to cater to our further energy demand. Herein, an excellent electrocatalyst of CoMoP nanosheet arrays grown on nickel foam (CoMoP NAs @NF) composite is constructed via a combination of hydrothermal and phosphating process for hydrogen evolution reaction (HER). SEM and TEM characterizations indicate the composite has a unique three-dimension structure, where CoMoP nanosheets uniformly grow on NF substrate. Due to the unique structure and the synergetic effect between CoMoP nanosheet and bare NF, electrochemical tests suggest that the composite has an excellent HER performance with a low overpotential of only 24 mV to achieve a current density of 10 mA cm−2 and Tafel slope of 44.6 mV dec−1. Moreover, a certain overpotential can be maintained at 10 mA cm−2 for over 20 h, suggesting its superior stability. Considering its superior HER performance and stability, we envision that this composite could be a prospective substitute for non-noble-metal HER catalysts for practical applications.

Submicron star-like ZnO (ZnO SZ) was synthesized via a facile hydrothermal method, and a series of composite photoanode materials with different ZnO SZ concentrations in the range from 0 wt.% to 0.20 wt.% were synthesized by a mechanical mixing method. The as-prepared samples were characterized by x-ray diffraction analysis, scanning electron microscopy, ultraviolet–visible (UV–Vis) absorption spectroscopy, etc. The results clearly showed that the mean diameter of the ZnO SZ was approximately 300 nm while its length was in the micrometer range, and the ZnO SZ was embedded homogeneously into the ZnO nanoparticle photoanode. Although UV–Vis spectral analysis revealed that increasing the ZnO SZ content decreased the dye adsorption density of the composite photoanode, the photocurrent density–voltage (J–V) characteristic indicated that dye-sensitized solar cells (DSSCs) using the ZnO SZ/ZnO composite photoelectrode exhibited significantly improved photovoltaic performance compared with those using pure ZnO nanoparticles. Electrochemical measurements revealed that DSSCs using 0.10 wt.% ZnO SZ showed improved efficiency of light energy conversion of 1.38%, being 43.75% higher than when using pure ZnO. All these results prove that incorporation of ZnO SZ into the ZnO nanoparticle photoelectrode represents a highly effective method for improving the photovoltaic properties of DSSCs.

CdS/TiO2 coaxial nanocables was synthesized through electrodeposition method with the assistant of porous anodic aluminum oxide (AAO) template. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The morphology results show that the external diameter of CdS/TiO2 coaxial nanocables is approximately 100 nm and the wall thickness is almost 20 nm, indicating that the TiO2 nanotubes are fully filled with CdS nanowires. The photo response shows that doping CdS nanowire arrays (NWAs) into TiO2 nanotube arrays (NTAs) could expand the spectral response of TiO2 from ultraviolet region to the visible light region. Meanwhile, compared with pure TiO2 NTAs, the CdS/TiO2 coaxial nanocables displayed an improved photodegradation efficiency for Rhodamine B (RhB) from 47.77 to 98.86%. As for the photocatalytic activity of hydrogen production, the H2 production evolution rate of CdS/TiO2 coaxial nanocables was 8.7 times higher than that of TiO2 NTAs within 200 min reaches as 1256 μmol/h. The enhancement of photocatalysis activity indicates that CdS/TiO2 coaxial nanocables has a potential application in photocatalytic field.

S-doped g-C3N4/TiO2 nanoparticle composites (TCNS) were generated by successfully calcinating a compound of thiourea and TiO2 at 550 °C; these composites serve as a promising photoanode material for dye-sensitized solar cells (DSSCs) with improved efficiency. TEM, HRTEM, XRD, UV–Vis and FTIR results showed that the surfaces of TiO2 nanoparticles were coated with a thin layer of sulfur-doped g-C3N4. The corresponding photoelectrochemical properties of the fabricated DSSCs were also studied. The DSSCs based on the TCNS photoelectrode shows a ratio of 4.87% in converting light into electricity, a short-circuit photocurrent of 10.41 mA cm−2, and an open-circuit voltage of 0.65 V, qualities which were well above those of DSSCs based on un-doped TCNS. The significant enhancement in DSSC performance is mainly due to the suppression of the recombination of electron–hole (e−–h+) pairs, suppression which also leads to an increase in open-circuit photovoltage, as well as photocurrent density under short circuit by the layer of sulfur-doped g-C3N4. Additionally, electrochemical impedance spectroscopy analysis proved that the electron transfer resistance is considerably reduced, and this reduction increases the power conversion efficiency.

The elastic slip and extension of a cable are important problems for a precision cable-drum drive system. Adjusting the design parameters (preload force, payload and so on) is an effective way of improving transmission performance. At present, most researchers focus on sliding mechanisms, Euler’s equation improvement and engineering applications. The effect of design parameters on the transmission performance has not been deeply investigated. In this paper, the static and dynamic performance of a cable-drum drive system was explored for improving precision and response, and the effect of preload force and payload on the static and dynamic performance was analyzed. The static performance was evaluated by the transmission error, which was determined by measuring the rotational angle of input and output drum using SCANCON encodes. The dynamic performance was evaluated by the response bandwidth, which was determined by measuring the amplitude-frequency and phase-frequency curve of cable-drum drive system using TIRA GmbH vibration test system. The results show that the maximum transmission error is 0.75 mrad at a rotational range of 180° when the external torque is 0.19 N×m. The transmission error increases with the increase of the drum rotation angle. The transmission error increases with the increase of the preload force and external torque. The response bandwidth can reach 56 Hz when the payload inertia is 0.0145 kg×m2, which decreases with increase of payload inertia. However, the preload force has little obvious influence on the response bandwidth when the preload force is changed from 99.85 N to 496.99 N. These results are helpful for the design improvement and theory research of precision cable-drum drive system in future.

The purpose of this paper is to investigate properties of traveling wave fronts for three species Lotka–Volterra system: the asymptotic behavior and uniqueness. Applying the Ikehara’s theorem, we determine the exponential rates of traveling wave fronts at the negative infinity. We further investigate the uniqueness of traveling wave fronts with the help of the sliding method.

Lysine is widely used in food, medical and feed industries. The biosynthesis of l-lysine is closely related to NADPH level, but the regulation mechanism between the biosynthesis of l-lysine in C. glutamicum and the cofactor NADPH is still not clear. Here, a high intracellular NADPH level strain C. glutamicum XQ-5Δpgi::(zwf-gnd) was constructed by blocking the glycolytic pathway and overexpressing the pentose phosphate pathway in the lysine-producing strain C. glutamicum XQ-5, and the intracellular NADPH level in strain XQ-5Δpgi::(zwf-gnd) was increased from 3.57 × 10–5 nmol/(104 cells) to 1.8 × 10–4 nmol/(104 cell). Transcriptome analyses pointed to Cgl2680 as an important regulator of NADPH levels and l-lysine biosynthesis in C. glutamicum. By knocking out the gene Cgl2680, the intracellular NADPH level of the recombinant C. glutamicum lysCfbr ΔCgl2680 was raised from 7.95 × 10–5 nmol/(104 cells) to 2.04 × 10–4 nmol/(104 cells), consequently leading to a 2.3-fold increase in the NADPH/NADP+ ratio. These results indicated that the regulator Cgl2680 showed the negative regulation for NADPH regeneration. In addition, Cgl2680-deficient strain C. glutamicum lysCfbr ΔCgl2680 showed the increase of yield of both l-lysine and l-leucine as well as the increase of H2O2 tolerance. Collectively, our data demonstrated that Cgl2680 plays an important role in negatively regulating NADPH regeneration, and these results provides new insights for breeding l-lysine or l-leucine high-yielding strain.

Permutation trinomials over finite fields are of great interest for their simple algebraic forms and important applications in many areas of mathematics and engineering. In this paper, six new classes of permutation trinomials over $$\mathbb {F}_{3^{3k}}$$ are presented based on the multivariate method. Their permutation properties are proved by using the resultant elimination method.

Amorphous molybdenum sulfide on P-doped carbon nanotubes (MoS x /P-CNTs) composite with an original leaves–branch architecture for hydrogen evolution reaction (HER) is successfully fabricated by urea-assisted synthesis via a facile hydrothermal process. It is found that urea used in the process of preparation played a crucial role in the establishment of this unique structure, where leaves-like MoS x nanosheets are uniformly anchored on P-CNTs substrate. Besides, the optimal amount of MoS x on P-CNTs bundles is investigated in this paper. Due to the synergistic coupling effects of MoS x nanosheets and P-CNTs bundles, as a result, the unique structure maintains abundant active sites, a high electrical conductivity as well as distinctive electrons transport mechanism, which gives the optimum MoS x /P-CNTs composite, a higher activity for HER with an overpotential of 151 mV (vs. RHE) to reach a current density of 10 mA cm−2 and a smaller Tafel slope of 49 mV dec−1. Stability tests indicate that the catalyst exhibits excellent electrochemical durability in 0.5 M H2SO4 solution. We envision that this work could provide new insights into the rational design of MoS x -based electrocatalysts for energy conversion and storage.

As a consequence of industrialization, urbanization, and population growth in the past decades, high nutrient concentrations from point and non-point sources in aquatic systems have caused major problems to the water quality in rivers, estuaries, and coastal waters. Although the nutrient pollution due to land use change cannot be ignored, the combined sewer overflows and discharging sites have been important point sources of nutrient pollution. Integrated hydrodynamic, chemical, and biological models developed in recent years, which simulate the nutrient transportation from both point and non-point sources, are useful tools to assist in identifying the transport and fate of nutrients from both point and non-point sources. In this paper, water quality data from published literature were reviewed and analyzed to evaluate nutrient (N and P) pollution in aquatic systems. An integrated monitoring and management plan should be continuously developed in the future to monitor and regulate nutrient discharges from point and non-point sources.

Permutation polynomials have important applications in cryptography, coding theory, combinatorial designs, and other areas of mathematics and engineering. Finding new classes of permutation polynomials is therefore an interesting subject of study. In this paper, for an integer s satisfying $$s=\frac{q^n-1}{2}+q^r$$ , we give six classes of permutation polynomials of the form $$(ax^{q^m}-bx+\delta )^s+L(x)$$ over $$\mathbb {F}_{q^n}$$ , and for s satisfying $$s(p^m-1)\equiv p^m-1\ (mod\ p^n-1)$$ or $$s(p^{{\frac{k}{2}}m}-1)\equiv p^{km}-1 (mod\ p^n-1)$$ , we propose three classes of permutation polynomials of the form $$(aTr_m^n(x)+\delta )^s+L(x)$$ over $$\mathbb {F}_{p^n}$$ , respectively.

This paper reviews recent progress in applying mineral magnetic methods in sediment pollution studies. Such applications include its use as a dating marker, as a proxy for heavy metal concentrations and to trace metal pollutant dispersal. The mineral magnetic method has been found to be a promising tool in a wide range of sediment metal pollution studies. However, its use as a proxy of heavy metal concentrations is not always straightforward. This reflects the potentially mixed origins of magnetic minerals in sediments which may have an anthropogenic, natural or mixed source. Furthermore, anthropogenic magnetic particles may not have a common source with heavy metals. The possible linkage between magnetic minerals and heavy metals is discussed. The role of sorting, sorption/desorption and post-depositional diagenesis on the magnetic mineral-heavy metal linkage is highlighted as still requiring careful consideration. It is suggested that detailed characterisation of magnetic mineralogy using combined magnetic, geochemical and mineralogical methods is critical to the optimization of sediment pollution studies using a mineral magnetic approach.

Background Elevated resting heart rate (HR) has emerged as a new risk factor for all-cause and cardiovascular mortality. The effect of marine-derived omega-3 long-chain polyunsaturated fatty acid (n−3 LCPUFAs) supplementation on HR was investigated as an outcome in many clinical trials. The present study was to provide an updated meta-analysis on the HR-slowing effect of n−3 LCPUFAs, and to differentiate the chronotropic effect between eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Methods PubMed and Cochrane databases were searched for relevant articles examining the effects of n−3 PUFAs on HR through May 2017. A random-effects model was used to generate the pooled effect sizes and 95% confidence intervals (CIs). The pooled effect sizes were presented as weighted mean differences (WMDs). Results A total of 51 randomized controlled trials (RCTs) with approximately 3000 participants were included in this meta-analysis. Compared to placebo, n−3 PUFA supplementation mildly but significantly reduced HR (−2.23 bpm; 95% CI: −3.07, −1.40 bpm). Moderate evidence of heterogeneity was observed among included trials (I 2 = 49.1%, P heterogeneity

Novel NiCoO2/rGO composites with a structure of NiCoO2 nanoparticles anchored on layers of reduced graphene oxide(rGO) were synthesized via a simple one-pot hydrothermal method and were used as faradaic electrodes for supercapacitors. The microstructures of NiCoO2/rGO composites were characterized by means of field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and thermogravimetric analysis(TGA). When acting as faradaic electrodes for supercapacitors, NiCoO2/rGO composites exhibited a specific capacity of 288 C/g at the current density of 2 A/g and maintained 139.98 C/g at 20 A/g. High capacity retention ratios up to 88% could be achieved after 1000 cycles at a current density of 2 A/g. The outstanding cycling stability was primarily attributed to the combination of mixed transition metal oxides and rGO, which not only maintains a high electrical conductivity for the overall electrode but also prevents the aggregation and volume expansion of electrochemical materials during the cycling processes.

CdTe nanoparticle-sensitized TiO2 nanotube arrays (CdTe/TiO2 NTAs) were prepared by combining the sol–gel method with the electrodeposition method by the aid of anodic aluminum oxide template. The morphology, structure and composition of the materials were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction (XRD). The photo response and photocatalytic activity of the materials were investigated by UV–Vis absorption spectroscopy. The results show that the pore diameter of the TiO2 nanotubes is about 120 nm and the wall thickness is approximately 30 nm. CdTe nanoparticles are deposited both inside and in the tube-to-tube voids of the TiO2 nanotubes. XRD analyses identify the anatase structure of TiO2 nanotubes and cubic sphalerite structure of CdTe. Compared with pure TiO2 nanotube film, the CdTe/TiO2 NTAs display a significant increase in absorption coefficient in the visible light and a higher activity for photodegrading Rhodamine B under Xe lamp irradiation with an increase from 34 to 88%. The results also show that CdTe/TiO2 NTAs exhibit better photoelectrochemical performance than TiO2 NTAs.

This study presents the results obtained from magnetic susceptibility and heavy metal (Cu, Zn, Pb, and Cr) concentration measurements of soil profiles collected from arable land and urban parks in Baoshan District, an industrial district of Shanghai, China. The study focuses on the investigation of vertical variations in magnetic susceptibilities and heavy metal concentrations and on correlations between magnetic susceptibilities and heavy metal concentrations in soil profiles. The results demonstrate that magnetic enhancement in the surface layer of the soil profile is associated with increased heavy metal pollution. The enrichment factors (EF) and the Tomlinson Pollution Load Index (PLI-EF) are calculated for estimating the level of heavy metal pollution of soil profiles in the study. The significant positive correlations between heavy metal contents, enrichment factors (EF), Tomlinson pollution load index (PLI-CF), modified Tomlinson pollution load index (PLI-EF), and magnetic susceptibility (c) indicate that much of the heavy metal contamination in the study area is linked to combustion derived particulate emissions. The results confirm that the combined magnetic measurement and heavy metal concentration analysis could provide useful information for soil monitoring in urban environments. However, the use of magnetic technique to locate the heavy metal pollution boundary in the soil profile of this studied area should be confirmed by further geochemical analysis.

The near wake of the polygonal cylinder with the side number N = 3 ~ ∞ is systematically studied based on particle image velocimetry (PIV) and load-cell measurements. Each cylinder is examined for two orientations, with either one leading side or leading corner. The Reynolds number Re = (1.0 ∼ 6.0) × 104 , defined by the longitudinally projected cylinder width. The dependence of the wake characteristic parameters on the cylinder orientation and N is discussed, and wake scaling analysis is conducted based on these parameters. It is found that the velocity deficit and half width of the wake scale well with the reverse flow zone length and recirculation bubble width, whilst the Strouhal number, drag and fluctuating lift coefficients scale well with the vortex formation length and wake width. The unveiled scaling relationships cast insight into the intrinsic physical connections between the aerodynamic forces and vortex formation and between the polygonal cylinder wakes of N = 3 ~ ∞, suggesting that the understanding of the time-mean wake behind individual polygonal cylinder can be unified to that of the circular cylinder wake.

Background The utilization of Chlorella for the dual goals of biofuel production and wastewater nutrient removal is highly attractive. Moreover, this technology combined with flue gas (rich in CO2) cleaning is considered to be an effective way of improving biofuel production. However, the sterilization of wastewater is an energy-consuming step. This study aimed to comprehensively evaluate a cost-effective method of culturing Chlorella pyrenoidosa in unsterilized piggery wastewater for biofuel production by sparging air or simulated flue gas, including algal biomass production, lipid production, nutrient removal rate and the mutual effects between algae and other microbes. Results The average biomass productivity of C. pyrenoidosa reached 0.11 g L−1 day−1/0.15 g L−1 day−1 and the average lipid productivity reached 19.3 mg L−1 day−1/30.0 mg L−1 day−1 when sparging air or simulated flue gas, respectively. This method achieved fairish nutrient removal efficiency with respect to chemical oxygen demand (43.9%/55.1% when sparging air and simulated flue gas, respectively), ammonia (98.7%/100% when sparging air and simulated flue gas, respectively), total nitrogen (38.6%/51.9% when sparging air or simulated flue gas, respectively) and total phosphorus (42.8%/60.5% when sparging air or simulated flue gas, respectively). Culturing C. pyrenoidosa strongly influenced the microbial community in piggery wastewater. In particular, culturing C. pyrenoidosa enriched the abundance of the obligate parasite Vampirovibrionales, which can result in the death of Chlorella. Conclusion The study provided a comprehensive evaluation of culturing C. pyrenoidosa in unsterilized piggery wastewater for biofuel production. The results indicated that this cost-effective method is feasible but has considerable room for improving. More importantly, this study elucidated the mutual effects between algae and other microbes. In particular, a detrimental effect of the obligate parasite Vampirovibrionales on algal biomass and lipid production was found. Electronic supplementary material The online version of this article (10.1186/s13068-019-1407-x) contains supplementary material, which is available to authorized users.

This paper makes qualitative analysis to the bounded traveling wave solutions for a kind of nonlinear dispersive-dissipative equation, and considers its solving problem. The relation is investigated between behavior of its solution and the dissipation coefficient. Further, all approximate damped oscillatory solutions when dissipation coefficient is small are presented by utilizing the method of undetermined coefficients according to the theory of rotated vector field in planar dynamical systems. Finally, error estimate is given by establishing the integral equation which reflects the relation between approximate and exact damped oscillatory solutions applying the idea of homogenization principle.

In this paper, we obtain existence and orbital stability results for the planar Schrodinger-Poisson system. Our results are based on the Gagliardo-Nirenberg inequality, the concentration-compactness principle, and the extremum principle in critical point theory.

Nitrogen limited but carbon excess condition was used to obtain high cellular lipid content and production. The maximum lipid production was 51 g/L, the lipid content in the dry cell was 60 %, and the lipid productivity was 0.53 g/L/h. In the fermentation, the content of lipid was raised from 20 % of dry cell weight to 60 %, and the proportion of oleic acid was raised from 66.8 to 72.5 %. Meanwhile, the metabolism of carotenoids switched to torulene, and its proportion was raised from 30 to 58 %. This was according to torulene had the better antioxidant ability than β-carotene to protect the strain from oxidative damage proved by their ABTS* radical scavenging activity and lipid peroxidation inhibition ability. Sporidiobolus pararoseus lipid was a good source of lipid not only because of its high oleic acid composition, but also the antioxidant ability of carotenoids in the lipid.

Boolean functions possessing multiple cryptographic criteria play an important role in the design of symmetric cryptosystems. The following criteria for cryptographic Boolean functions are often considered: high nonlinearity, balancedness, strict avalanche criterion, and global avalanche characteristics. The trade-off among these criteria is a difficult problem and has attracted many researchers. In this paper, two construction methods are provided to obtain balanced Boolean functions with high nonlinearity. Besides, the constructed functions satisfy strict avalanche criterion and have good global avalanche characteristics property. The algebraic immunity of the constructed functions is also considered.