Search

A high time resolution synchronous sampling method al ong with determination of stable carbon isotopes of gaseous water-soluble organic carbon (WSOCg) and particulate water-soluble organic carbon (WSOCp) was realized in this research through equipment modification and method improvement. It was found that WSOCg has significant higher concentration than WSOCp and a more depleted δ13C. Both concentrations of WSOCp and WSOCg have the seasonal variation characteristics of high in winter (WSOCp=15.7±3.9µg/m³; WSOCg=42.4±6.0µg/m³) and low in summer (WSOCp=5.9±1.8µg/m³; WSOCg=25.2±5.2µg/m³), with greater increase in WSOCp (167%) than that in WSOCg (68%). During wintertime, WSOCp and WSOCg had similar daily variation characteristics of concentration, and opposite daily variation characteristics of δ13C. WSOCp had a bimodal distribution with obvious low value at sunrise and sunset, while δ13C WSOCp had a unimodal distribution with low in daytime (-24.6±1.1‰) and high in nighttime (- 22.3±1.7‰). WSOCg and δ13C-WSOCg had same distribution with high in daytime and (49.3±8.8µg/m³; -27.9±1.1‰) low in nighttime (38.3±4.6µg/m³; -29.9±0.4‰). Combining the δ13C variation characteristics with the synchronous observation results of meteorological conditions, gaseous precursor pollutants, gaseous oxidants, gaseous acids and fine particle components, the restriction factors of WSOC gas-particle distribution mechanism were discussed. The presence of radiation rather than its intensity decided whether generations process of WSOCp and WSOCg are divided, for δ13C-WSOC of two phases showed significant correlation only during daytime. Meteorological conditions, gaseous precursor pollutants, gaseous oxidants and gaseous acids restrict the gas particle distribution of WSOC by affecting the aging process of WSOCp and WSOCg, gas particle conversion ratio of semi-volatile organic compounds (SVOC) and the gas phase and liquid phase generation ratio of WSOCp. At the same time, the gas-particle distribution process of WSOC is strongly related to the formation of secondary inorganic ions (nitrate, sulfate, ammonium), and the gas-particle distribution between gaseous nitrous acid and nitrite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ga-doped TiO 2 with rich OVs were prepared by a sol–gel method. • The existence of OVs leads to the generation of a new energy level. • Ga-doped and enriched OVs induce high separation rate of carriers. • Ga 0.6 /OVs-TiO 2 exhibits the highest photocatalytic activity. Titanium dioxide (TiO 2) is widely regarded as one of the most promising semiconductors among the various photocatalytic materials. In this demonstration, Ga-doped TiO 2 with rich oxygen vacancies (OVs) was synthesized by a sol–gel method. Systematic characterization provides soild attest for the successful doping of Ga and the enhancement level of OVs. The large specific surface area provides richer surface-active sites for Ga/OVs-TiO 2 samples through BET test. The photoelectric performance test shows that Ga doping and the existence of rich OVs can effectively improve the photogenerated carriers separation and migration efficiency of TiO 2. The degradation results for rhodamine B (RhB) and tetracycline hydrochloride (TC) attest that the photocatalytic efficiency of Ga-doped TiO 2 is better than that of the reference TiO 2. The capture experiment further exhibits that hydroxyl radical and superoxide radical are the main active species in photocatalytic degradation. The synergistic effect of Ga doping and OVs significantly improves the separation and migration of photogenerated carriers, therefore boosting the photocatalytic performance. This work provides a reliable guide for utilization of Ga and a solid strategy of element doping to improve the photocatalytic performance of TiO 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapeseed stem powder was employed to prepared OVs-BiOCl. • SP-BiOCl shows richer OVs than the reference BiOCl. • The separation rate of photo-generated carriers of RSP-BiOCl is largely enhanced. • RSP-BiOCl exhibits higher activity than the reference BiOCl. Construction of oxygen vacancies (OVs) is a reliable strategy to boost photocatalytic activity of a photocatalyst containing oxygen atom. OVs can accelerate the separation of photoinduced carriers, activate O 2 absorbed to yield ⋅O 2 –, elevating the photocatalytic activity. However, it is still a serious challenge to introduce plentiful OVs by a facile and wild channel. In this study, BiOCl with enriched OVs was successfully prepared with the assistance of rapeseed stem powder (RSP), which is an agricultural waste, achieving remarkably boosted photocatalytic activity toward removal of rhodamine B (RhB) and perfluorooctanoic acid (PFOA). The observations firmly confirm that the existence of RSP in the preparation system affects the crystal growth of BiOCl, induces abundant OVs, therefore, BiOCl prepared displays high specific surface area and separation rate of photoinduced carriers. Photocatalytic activity of RSP-BiOCl toward detoxification of RhB and PFOA is 3.47 times and 1.39 times of that of the blank BiOCl under visible light and UV light irradiation, respectively. RSP assisted-preparation is a solid approach to heighten the activity of BiOCl. [ABSTRACT FROM AUTHOR]

The implicit finite difference scheme with the shifted Gru¨\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\ddot{\textrm{u}}$$\end{document}nwald formula for discretizing the two-dimensional spatial fractional diffusion equations can result in discrete linear systems whose coefficient matrices are the sum of the identity matrix and a block-Toeplitz with Toeplitz-block matrix. For these symmetric positive definite coefficient matrices, we construct block-circulant with circulant-block preconditioners to further accelerate the convergence rate of the CG method. We analyze the eigenvalue distributions for the corresponding preconditioned matrices. Theoretical results show that the eigenvalues of the preconditioned matrices are weakly clustered around 1 and the convergence of the preconditioned CG method with the block-circulant with circulant-block preconditioner is weakly dependent on the mesh size. Numerical experiments demonstrate that this structured preconditioner can improve the convergence behavior of the CG method. Moreover, this approach is superior to the preconditioned CG methods incorporated with the block diagonal and block tridiagonal preconditioners in both iteration counts and computing times. [ABSTRACT FROM AUTHOR]

Generally, a traditional method to generate circularly polarized waves faces limitations like the narrow band, bulky volume and low efficiency. In this paper, a linear-to-circular (LTC) polarization converter based on metasurface with high efficiency and maneuverable ultra-wideband is proposed. By utilizing the ellipse-shaped structure on reflective metasurface, the LTC polarization converting condition can be achieved at four closer frequencies, leading to a quite wide frequency band. The simulated results show that the axial ratio of the reflective circularly polarized wave is lower than 3 dB within the frequency band of 10.21–24.97 GHz, and a relative band reaches above 83.91%. Furthermore, the bandwidth of the polarization conversion can be sustained from 10.21 to 22.71 GHz at incident an angle of 48°. The electrical field and current flows are given to analyze the circular polarization performance. For validation, a sample is fabricated and measured; measured results and simulated results coincide with each other. The proposed LTC polarization converter is easy in terms of design and fabrication complexity, showing promising potentials in real-world circularly polarized wave generator applications. [ABSTRACT FROM AUTHOR]

The paper studies the initial-boundary-value problem (IBVP) of a nonlinear Schrödinger equation posed on a strip domain R × [ 0 , 1 ] with non-homogeneous Dirichlet boundary conditions. For 0 ≤ s < 1 / 2 , if the initial condition φ (x , y) is in Sobolev space H s (R × [ 0 , 1 ]) and the boundary condition h (x , t) is in H s (R 2) = { h (x , t) ∈ L 2 (R 2) | (1 + | λ | + | ξ |) 1 2 (1 + | λ | + | ξ | 2) s 2 h ˆ (λ , ξ) ∈ L 2 (R 2) } where h ˆ is the Fourier transform of h with respect to t and x , the local well-posedness of the IBVP in C ([ 0 , T ] ; H s (R × [ 0 , 1 ])) is proved. For 1 / 2 < s < 5 / 2 , because of compatibility conditions, the same local well-posedness result holds if an extra condition h (x , 0) ∈ H s + 1 2 (R) is added. Moreover, the global well-posedness is obtained for s = 1. The basic idea used here relies on the derivation of an integral operator for the non-homogeneous boundary data and the proof of Strichartz's estimates for this operator. After the problem is transformed to finding a fixed point of an integral operator, the contraction mapping argument then yields a fixed point using the Strichartz's estimates for initial and boundary operators. The global well-posedness is proved using a-priori estimates of the solutions. [ABSTRACT FROM AUTHOR]

We propose an iteration method to recover a space-dependent source for a time-fractional diffusion equation from the final measurement. Based on the conditional stability of the inverse problem, we prove the convergence of the iterative regularization method under the a priori parameter choice rule and the a posteriori parameter choice rule, respectively. Numerical examples in one dimension and two dimension are given to validate the effectiveness of the presented method. [ABSTRACT FROM AUTHOR]

We study an inverse problem of determining the Robin coefficient of fractional diffusion equation from a nonlocal boundary condition. Based on the property of Caputo fractional derivative, the uniqueness is proved. The numerical schemes for the direct problem and the inverse problem are developed. Three examples are given to show the effectiveness of the presented methods. [ABSTRACT FROM AUTHOR]

The Fast Radio Burst FRB121102 has been observed to repeat in an irregular fashion. Using published timing data of the observed bursts, we show that Poissonian statistics are not a good description of this random process. As an alternative, we suggest to describe the intervals between bursts with a Weibull distribution with a shape parameter smaller than one, which allows for the clustered nature of the bursts. We quantify the amount of clustering using the parameters of the Weibull distribution and discuss the consequences that it has for the detection probabilities of future observations and for the optimization of observing strategies. Allowing for this generalization, we find a mean repetition rate of r = 5.7+3.0 -2.0 per day and index k = 0.34+0.06 -0.05 for a correlation function ξ(t) = (t/t0)k -1. [ABSTRACT FROM AUTHOR]

As a typical Bi-based photocatalyst, BiOCl has been received increasing attention because of its many advantages. However, poor visible light response ability and high recombination rate of photoexcited charge pairs significantly inhibit the intense application of BiOCl, therefore, it is considerable to develop a strategy to overcome the inherent shortcomings of BiOCl to boost its photocatalytic properties. The former works have strongly affirmed that coupling carbon quantum dots (CQDs) with BiOCl to construct heterojunctions is a practical method to boost the photoactivity of BiOCl. In this demonstration, water hyacinth powder was used to provide raw material for CQDs, and CQDs/OVs-BiOCl heterostructures were in-situ fabricated through a solvothermal synthesis. The successful modification of CQDs on BiOCl and the formation of abundant oxygen vacancies (OVs) were confirmed by several analytical methods. The test results of photoelectric property reveal that CQDs/OVs-BiOCl has faster photogenerated charge separation rate than the reference BiOCl. Photoactivity of all the samples was examined by destruction of rhodamine B (RhB) and defluorination of perfluorooctanoic acid (PFOA). The CQDs/OVs-BiOCl heterostructures exhibit the ascendant photocatalytic destruction activity. Among them, the degradation efficiency of RhB over 1%CQDs/OVs-BiOCl under visible light irradiation is 2.6 folds of that of over the reference BiOCl. Besides, the defluorination rate of PFOA on 1%CQDs/OVs-BiOCl under UV light irradiation is 1.4 times of that of on BiOCl. The cyclic experimental results solidly prove that the CQDs/OVs-BiOCl samples have outstanding stability and good application prospect. Free radical detection experiments reveal that 1%CQDs/OVs-BiOCl reaction system produces more active species than the reference BiOCl system, and ·O 2 - is the most important active substance. Additionally, the total organic carbon (TOC) test strongly demonstrate that RhB can be effectively mineralized into inorganic small substances on 1%CQDs/OVs-BiOCl under light shine. Based on the results of all the characterizations, a photocatalytic improvement mechanism for CQDs/OVs-BiOCl was reasonably elaborated. This work provides a new approach to obtain CQDs to modify BiOCl, which not only improves the photocatalytic degradation activity of BiOCl, but also achieves the purpose of use waste to treat waste. [ABSTRACT FROM AUTHOR]

The space fractional coupled nonlinear Schrödinger (CNLS) equations are discretized by an implicit conservative difference scheme with the fractional centered difference formula, which is unconditionally stable. The coefficient matrix of the discretized linear system is equal to the sum of a complex scaled identity matrix and a symmetric positive definite diagonal-plus-Toeplitz matrix. The Hermitian and skew-Hermitian splitting (HSS) method and the partially inexact HSS (PIHSS) method are employed to solve the discretized linear system. In the inner iteration processes of the HSS method, we only need to solve the linear sub-systems associated with the Hermitian part inexactly by the conjugate gradient (CG) method, resulting in PIHSS iteration method. Theoretical analyses show that both HSS and PIHSS methods are unconditionally convergent. Numerical examples are given to demonstrate the effectiveness of the HSS iteration and the PIHSS iteration. [ABSTRACT FROM AUTHOR]

The ozonation of hydroxyl compounds (e.g., sugars and alcohols) gives a broad range of products such as alcohols, aldehydes, ketones, and carboxylic acids. This study developed and optimized a two-step derivatization procedure for analyzing polar products of aldehydes and carboxylic acids from the ozonation of diethylene glycol (DEG) in a non-aqueous environment using gas chromatography-mass spectrometry. Experiments based on Central Composite Design with response surface methodology were carried out to evaluate the effects of derivatization variables and their interactions on the analysis. The most desirable derivatization conditions were reported, i.e., oximation was performed at room temperature overnight with the o-(2,3,4,5,6-pentafluorobenzyl) hydroxyl amine to analyte molar ratio of 6, silylation reaction temperature of 70°C, reaction duration of 70 min, and N,O-bis(trimethylsilyl)-trifluoroacetamide volume of 12.5 µL. The applicability of this optimized procedure was verified by analyzing DEG ozonation products in an ultrafine condensation particle counter simulation system. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O) is a potent greenhouse gas and is mainly produced from agricultural soils especially vegetable soils with large N fertilizer input. How future projected climate change may impact on the N 2 O emissions and the related key (de)nitrifier communities in such ecosystem is poorly understood. The aim of this field study was to determine the interactive effects of a simulated warmer and drier climate on (de)nitrifier communities and N 2 O emissions in a vegetable soil. A warmer (+3.3 °C) and drier climate (−14.4% soil moisture content) was created with greenhouses with or without urea N fertilizer application. The variation of microbial population abundance and community structure of Ammonia-oxidizing archaea (AOA), bacteria (AOB) and denitrifiers ( nirK/S , nosZ ) were determined using Real time-PCR and sequencing. The results showed a strong interactive effect of simulated climate change with N fertilizer applications, whereby the impacts of warmer and drier conditions on the microbial communities and N 2 O emissions were more evident when N fertilizer was applied. The simulated warmer and drier conditions in the greenhouses significantly decreased N 2 O emissions largely due to the drier soil conditions. The abundance and community structure of AOB showed more rapid responses than AOA under the simulated climate conditions when N fertilizer was applied. Changes of AOB community structure were significantly correlated with soil moisture content and NH 4 + -N concentration. The simulated climate change did not affect the nirS gene abundance, but significantly increased nirK gene abundance, and significantly decreased nosZ gene abundance with urea application. N 2 O emissions were positively correlated with the bacterial amoA abundance and with the ratio of nirK / nosZ gene abundance. Therefore, bacterial amoA , nirK- and nosZ- type denitrifiers are the dominant microbial communities which were affected by the simulated climate conditions and are thus critically important for N cycling in vegetable soils under a changing climate. [ABSTRACT FROM AUTHOR]

Low activity of photocatalysts is a serious bottleneck to the practical application of photocatalytic technology. In this paper, a series of BiOCl composite photocatalysts containing carbon quantum dots (CQDs) were successfully prepared by adding Panax notoginseng powder (PNP) to the solvothermal synthesis system of BiOCl as a template agent and a raw material for 0D CQDs. CQDs/BiOCl exhibit 2D flake structures and 3D flower-like microspheres self-assembled from thin flakes, holding rich oxygen vacancies (OVs). After detailed characterization, it was found that the amount of OVs on BiOCl could be regulated according to the amount of PNP added. The CQDs/OVs-BiOCl photocatalysts exhibit higher photogenerated charge separation efficiency and photocatalytic activity than the bare BiOCl. When the mass ratio of PNP/BiOCl is 1.0%, the photocatalyst demonstrates the maximum degradation activity for rhodamine B (RhB) and perfluorooctanoic acid (PFOA). In view of the solid observations, a photocatalytic enhancement mechanism of CQDs/BiOCl was elucidated. • > Modification of BiOCl by PNP can facilely regulate the morphology. • > The existence of PNP can adjust the concentration of OVs. • > Separation of carriers has been significantly promoted. • > CQDs/OVs-BiOCl samples possesses prominent photocatalytic activity. [ABSTRACT FROM AUTHOR]

• AgBr was prepared by a hydrothermal method with PVP. • Separation of photoactivated carriers has been largely promoted. • The level of •O 2 − was greatly boosted. • PVP-AgBr possess superior photocatalytic activity. In this paper, AgBr photocatalyst was prepared by a precipitation method using silver nitrate and potassium bromide as raw materials. The effects of polyvinylpyrrolidone (PVP) on the preparation and photocatalytic property of AgBr were investigated. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), surface photovoltage (SPS), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and specific surface area (BET). Using rhodamine B as a model pollutant, photocatalytic performance of the photocatalyst prepared was tested under visible light irradiation. The results indicate that AgBr prepared by adding of PVP has superior photocatalytic activity. Under visible light irradiation, the destruction rate constant of rhodamine B (RhB) on PVP-AgBr is 4.79 times of that on the reference AgBr. [ABSTRACT FROM AUTHOR]

The fractional diffusion equation is discretized by an implicit finite difference scheme with the shifted Grünwald formula, which is unconditionally stable. The coefficient matrix of the discretized linear system is equal to the sum of the identity matrix with two diagonal-times-Toeplitz matrices. In this paper, the alternating direction implicit (ADI)-like method based on the classical ADI iteration is proposed to solve the discretized linear system. Theoretical analyses show that the ADI-like iteration method is convergent. Each iteration of this method requires the solutions of two linear systems with Hessenberg coefficient matrices. These two systems can be solved effectively by Hessenberg LU factorization. Numerical examples are presented to illustrate the effectiveness of the ADI-like iteration method. [ABSTRACT FROM AUTHOR]

The implicit conservative difference scheme with the fractional centered difference formula, which is unconditionally stable, is employed to discretize the space fractional coupled nonlinear Schrödinger equations. The coefficient matrix of the discretized linear system is equal to the sum of a complex scaled identity matrix which can be written as the imaginary unit times the identity matrix and a symmetric diagonal-plus-Toeplitz matrix. In this paper, the HSS-like iteration method is proposed to solve the discretized linear system. Theoretical analyses show that the HSS-like iteration method is unconditionally convergent. Numerical examples are presented to illustrate the effectiveness of the HSS-like iteration method. [ABSTRACT FROM AUTHOR]

So far there is only indirect evidence that the Universe is undergoing an accelerated expansion. The evidence for cosmic acceleration is based on the observation of different objects at different distances and requires invoking the Copernican cosmological principle and Einstein's equations of motion. We examine the direct observability using recession velocity drifts (Sandage-Loeb effect) of 21-cm hydrogen absorption systems in upcoming radio surveys. This measures the change in velocity of the same objects separated by a time interval and is a model-independent measure of acceleration. We forecast that for a CHIME-like survey with a decade time span, we can detect the acceleration of a ΛCDM universe with 5σ confidence. This acceleration test requires modest data analysis and storage changes from the normal processing and cannot be recovered retroactively. [ABSTRACT FROM AUTHOR]

Abstract: When the implicit finite difference scheme and linearization technique in conjunction with the artificial compressibility method are employed to discretize the unsteady incompressible Navier–Stokes equations, in each pseudo-time step, a structured system of linear equations is obtained and needs to be solved numerically. In this paper, preconditioning techniques are applied to solve such linear systems. Numerical example is given to illustrate the effectiveness of the proposed method. We also find that a combination of the linearization technique with the preconditioned GMRES method is quite efficient for the implicit finite difference discretization of the incompressible Navier–Stokes equations. [Copyright &y& Elsevier]

When the artificial compressibility method in conjunction with high-order upwind compact finite difference schemes is employed to discretize the steady-state incompressible Navier-Stokes equations, in each pseudo-time step we need to solve a structured system of linear equations approximately by, for example, a Krylov subspace method such as the preconditioned GMRES. In this paper, based on the special structure and concrete property of the linear system we construct a structured preconditioner for its coefficient matrix and estimate eigenvalue bounds of the correspondingly preconditioned matrix. Numerical examples are given to illustrate the effectiveness of the proposed preconditioning methods. [ABSTRACT FROM AUTHOR]

In order to solve the large sparse systems of linear equations arising from numerical solutions of two-dimensional steady incompressible viscous flow problems in primitive variable formulation, Ran and Yuan [On modified block SSOR iteration methods for linear systems from steady incompressible viscous flow problems, Appl. Math. Comput. 217 (2010), pp. 3050–3068] presented the block symmetric successive over-relaxation (BSSOR) and the modified BSSOR iteration methods based on the special structures of the coefficient matrices. In this study, we present the modified alternating direction-implicit (MADI) iteration method for solving the linear systems. Under suitable conditions, we establish convergence theorems for the MADI iteration method. In addition, the optimal parameter involved in the MADI iteration method is estimated in detail. Numerical experiments show that the MADI iteration method is a feasible and effective iterative solver. [ABSTRACT FROM AUTHOR]

Abstract: In order to solve the large sparse systems of linear equations arising from numerical solutions of two-dimensional steady incompressible viscous flow problems in primitive variable formulation, we present block SSOR and modified block SSOR iteration methods based on the special structures of the coefficient matrices. In each step of the block SSOR iteration, we employ the block LU factorization to solve the sub-systems of linear equations. We show that the block LU factorization is existent and stable when the coefficient matrices are block diagonally dominant of type-II by columns. Under suitable conditions, we establish convergence theorems for both block SSOR and modified block SSOR iteration methods. In addition, the block SSOR iteration and AF-ADI method are considered as preconditioners for the nonsymmetric systems of linear equations. Numerical experiments show that both block SSOR and modified block SSOR iterations are feasible iterative solvers and they are also effective for preconditioning Krylov subspace methods such as GMRES and BiCGSTAB when used to solve this class of systems of linear equations. [Copyright &y& Elsevier]

The overall goal of this study was to determine the molecular and metabolic responses of chemostat cultures of model nitrifying bacteria to imposition of and recovery from transient anoxic conditions. Based on the study, a specific directionality in nitrous oxide (N2O) and nitric oxide (NO) production was demonstrated. N2O production was only observed during recovery to aerobic conditions after a period of anoxia and correlated positively with the degree of ammonia accumulation during anoxia. NO, on the other hand, was emitted mainly under anoxia. The production of NO was linked to a major imbalance in the expression of the nitrite reductase gene, which was overexpressed during transient anoxia. In contrast, genes coding for ammonia and hydroxylamine oxidation and nitric oxide reduction were generally under-expressed during transient anoxia. These results are different from the observed parallel expression and activity of nitrite and nitric oxide reductase in heterotrophic bacteria subjected to transient oxygen cycling. Unlike NO, the production of N2O could not be solely correlated to gene expression patterns and likely involved responses at the enzyme activity or metabolic levels. Based on experimental data, the propensity of the nitrifying cultures for N2O production is related to a shift in their metabolism from a low specific activity (q < qmax) toward the maximum specific activity (qmax). [ABSTRACT FROM AUTHOR]

We examined the presence of iron-oxidizing bacteria (IOB) at a groundwater surface water interface (GSI) impacted by reduced groundwater originating as leachate from an upgradient landfill. IOB enrichments and quantifications were obtained, at high vertical resolution, by an iron/oxygen opposing gradient cultivation method. The depth-resolved soil distribution profiles of water content, Fe2+, and total Fe indicated sharp gradients within the top 10 cm sediments of the GSI, where the IOB density was the highest. In addition, the vertical distribution of iron-reducing bacteria at the same sampling site mirrored the IOB distribution. Clone libraries from two separate IOB enrichments indicated a stratified IOB community with clear differences at short vertical distances. Alpha- and Betaproteobacteria were the dominant phylotypes. Clones from the near-surface sediment (1–2 cm below ground surface) were dominated by members of the Bradyrhizobiaceae and Comamonadaceae; clones from the deeper sediments were phylogenetically more diverse, dominated by members of the Rhodocyclaceae. The iron deposition profiles indicated that active iron oxidation occurred only within the near-to-surface GSI sediments. The match between the iron deposition profiles and the IOB abundance profiles strongly hints at the contribution of the IOB community to Fe oxidation in this Fe-rich GSI ecosystem. [ABSTRACT FROM AUTHOR]

Background: Nitrosomonas europaea is a widely studied chemolithoautotrophic ammonia oxidizing bacterium. While significant work exists on the ammonia oxidation pathway of N. europaea, its responses to factors such as dissolved oxygen limitation or sufficiency or exposure to high nitrite concentrations, particularly at the functional gene transcription level are relatively sparse. The principal goal of this study was to investigate responses at the whole-cell activity and gene transcript levels in N. europaea 19718 batch cultures, which were cultivated at different dissolved oxygen and nitrite concentrations. Transcription of genes coding for principal metabolic pathways including ammonia oxidation (amoA), hydroxylamine oxidation (hao), nitrite reduction (nirK) and nitric oxide reduction (norB) were quantitatively measured during batch growth, at a range of DO concentrations (0.5, 1.5 and 3.0 mg 02/L). Measurements were also conducted during growth at 1.5 mg 02/L in the presence of 280 mg- N/L of externally added nitrite. Results: Several wide ranging responses to DO limitation and nitrite toxicity were observed in N. europaea batch cultures. In contrast to our initial hypothesis, exponential phase mRNA concentrations of both amoA and hao increased with decreasing DO concentrations, suggesting a mechanism to metabolize ammonia and hydroxylamine more effectively under DO limitation. Batch growth in the presence of 280 mg nitrite-N/L resulted in elevated exponential phase nirK and norB mRNA concentrations, potentially to promote utilization of nitrite as an electron acceptor and to detoxify nitrite. This response was in keeping with our initial hypothesis and congruent with similar responses in heterotrophic denitrifying bacteria. Stationary phase responses were distinct from exponential phase responses in most cases, suggesting a strong impact of ammonia availability and metabolism on responses to DO limitation and nitrite toxicity. In general, whole-cell responses to DO limitation or nitrite toxicity, such as sOUR or nitrite reduction to nitric oxide (NO) did not parallel the corresponding mRNA (r7ir/K) profiles, suggesting differences between the gene transcription and enzyme translation or activity levels. Conclusions: The results of this study show that N. europaea possesses specific mechanisms to cope with growth under low DO concentrations and high nitrite concentrations. These mechanisms are additionally influenced by the physiological growth state of N. europaea cultures and are possibly geared to enable more efficient substrate utilization or nitrite detoxification. [ABSTRACT FROM AUTHOR]

Sampling techniques with centimeter-scale spatial resolution were applied to investigate biogeochemical processes controlling groundwater arsenic fate across the groundwater--surface water interface at a site characterized by fine sediments (40% sand, 46% silt, 14% clay). Freeze-core sediment collection gave more detailed and depth-accurate arsenic and iron contaminant and microbial distributions than could be obtained with the use of a hand auger. Selective chemical extractions indicated that greater than 90% of the arsenic was strongly sorbed to very amorphous iron oxyhydroxides. These solids accounted for more than 80% of the total iron in the sediments. Microbial enrichments indicated that iron-oxidizing bacteria (IOB) were up to 1% of the total bacterial abundance, whereas iron-reducing bacteria (IRB) were about two orders of magnitude less abundant than IOB. The abundance of IRB mirrored the IOB depth profile. Push-point pore-water sampling captured large amounts of sediment fines, even with controlled (20 ml/min) water withdrawal, thereby necessitating filtration before water quality analysis. Bead columns containing glass media enabled short-term (29 d) characterization of pore water-to-sediment transfer of arsenic and iron. Bead columns indicated quantitative capture of groundwater arsenic and iron during 2003, suggesting that freeze-core inventories corresponded to 2 to 20 years of accumulation, depending on location. [ABSTRACT FROM AUTHOR]

Background: Restriction of fat intake has been effective in improving insulin sensitivity in obese and type 2 diabetic subjects, but what effects the recommended diet (less than 30% of total calories from fat) have not been elucidated in subjects with type 2 diabetes. The purpose of this study was to test the effects of oral fat challenge, composing 30% calories of a meal, on blood glucose, insulin, lipid, leptin, plasminogen activator inhibitor-1 (PAI-1) and tumor necrosis factor-α (TNF-α). Design and Methods: Blood glucose, insulin, lipid, leptin, TNF-α and PAI-1 were compared in 14 type 2 diabetic patients and 10 normal subjects after an oral fat challenge upto 2 hours (fasting, 15 min, 30 min, 45 min, 60 min, 90 min and 120 min). Results: Postprandial glucose, total cholesterol, leptin, PAI-1 levels did not differ significantly from levels at fasting. Serum triglyceride increased significantly from baseline only in diabetic patients (P = 0.042). Serum insulin increased postprandially in both groups (P = 0.028 in diabetic group and P = 0.055 in normal group), with displaying a prolonged insulin response in diabetic subjects. TNF-α decreased postprandially in both groups without significant difference, although diabetic patients have higher baseline levels (P = 0.024 compared to normal subjects). Conclusions: Oral fat load does not have an acute effect on blood glucose, total cholesterol, leptin and PAI-1 levels in both type 2 diabetic and normal subjects. TNF-α value showed decreased trend in both diabetic and normal subjects. The tendency of a delayed postprandial insulin response and elevated serum triglyceride level in diabetic subjects might be related to insulin resistance at the level of adipose tissue. Additional research is needed to assess the impact of the use of fat contents on the macronutrient composition of the diet, and potentially healthy and nutritional benefits for patients with diabetes. [ABSTRACT FROM AUTHOR]

A simple approach to reduce the governing equations for orthotropic corrugated-core sandwich plates to a single equation containing only one displacement function is presented, and the exact solution of the natural frequencies for rectangular corrugated-core sandwich plates with all edges simply-supported is obtained. Furthermore, two special cases of practical intersts are discussed in details. [ABSTRACT FROM AUTHOR]

Decarbonylative and dehydrogenative cascade annulation of aldehydes with N‐(o‐cyanobiaryl)acrylamides was developed for the synthesis of a broad spectrum of alkyl‐ and carbonyl‐substituted pyrido[4,3,2‐gh]phenanthridines. Secondary and tertiary aldehydes can undergo the decarbonylative cascade under DTBP/malonic acid conditions, while aryl, primary, and secondary aldehydes can undergo dehydrogenative reaction under TBHP system. Such transformations were triggered by alkyl and acyl radicals, and the annulations were accomplished through intramolecular additions of carbon‐centered radical to nitrile group and iminyl radical to aromatic ring. [ABSTRACT FROM AUTHOR]

• Formulated continuous approximation model for planning the coordinated skip-stop services. • Modeled general coordination plans in which headways have integer common multiples. • The coordination brings 2–3% additional benefit to skip-stop services. • The common-headway plan works robustly better than others under various scenarios. This paper develops a continuum approximation model for simultaneously designing and coordinating an AB-type skip-stop service, which had been successfully operated in many places (e.g., Chicago, Philadelphia, and Portland in US and Santiago in Chile). The model accounts for spatially heterogeneous demand patterns in transit corridors. Thanks to the parsimonious property, a solution algorithm is developed using calculus of variations and direct search method. In numerical experiments, a variety of scenarios were examined with respect to 14 operational schemes (i.e., the all-stop scheme, the uncoordinated skip-stop scheme, and the coordinated ones of 12 coordination plans), 2 transit modes (i.e., regular bus and rail), and 3 demand patterns (i.e., uniform, low-varied and high-varied demand). The results indicate: (i) the additional benefit of schedule coordination is 2–3% for uncoordinated skip-stop services, which eventually may add up to 6% cost saving as against the traditional all-stop service; (ii) among all coordination plans, the simplest common-headway plan often works best in all tested scenarios; and (iii) for rail system, the operation of the coordinated skip-stop service is very costly due to the requirement of building an extra track, and positive benefit only emerges in the very busy corridors. Lastly, a case study in Chengdu (China) using real surveyed demand data illustrates the application of our model. [ABSTRACT FROM AUTHOR]

A diode has been realised using a silicon junctionless (JL) transistor. The device contains neither PN junction nor Schottky junction. The device is measured at different temperatures. The characteristics of the JL diode are essentially identical to those of a regular PN junction diode. The JL diode has an on/off current ratio of 108, an ideality factor of 1.09, and a reverse leakage current of 1 × 10-14 A at room temperature. The mechanism of the leakage current is discussed using the activation energy (EA). The turn-on voltage of the device can be tuned by JL transistor threshold voltage. [ABSTRACT FROM AUTHOR]

Chiral symmetry is maximally violated in weak interactions [1], and such microscopic asymmetries in the early Universe might leave observable imprints on astrophysical scales without violating the cosmological principle. In this Letter, we propose a helicity measurement to detect primordial chiral violation. We point out that observations of halo-galaxy angular momentum directions (spins), which are frozen in during the galaxy formation process, provide a fossil chiral observable. From the clustering mode of large scale structure of the Universe, we construct a spin mode in Lagrangian space and show in simulations that it is a good probe of halo-galaxy spins. In the standard model, a strong symmetric correlation between the left and right helical components of this spin mode and galaxy spins is expected. Measurements of these correlations will be sensitive to chiral breaking, providing a direct test of chiral symmetry breaking in the early Universe. [ABSTRACT FROM AUTHOR]

Summary: When the implicit, conservative difference scheme with the fractional centered difference formula is employed to discretize the space fractional coupled nonlinear Schrödinger equations, in each time step, we need to solve a complex symmetric linear system. The real part of the coefficient matrix is a symmetric Toeplitz‐plus‐diagonal matrix, whereas the imaginary part is the identity matrix. In this paper, a structure preserving preconditioner and a circulant preconditioner are proposed for such Toeplitz‐like matrix. Theoretically, tight bounds for eigenvalues of the preconditioned matrices are derived. Numerical implementations show that Krylov subspace iteration methods such as BiCGSTAB, when accelerated by the proposed preconditioners, are efficient solvers for solving the discretized linear system. [ABSTRACT FROM AUTHOR]

[Display omitted] The introduction of nitrogen vacancies into polymeric carbon nitride (PCN) has been attested to be a reliable strategy to enhance photocatalytic performance. Nitrogen vacancies were considered as active sites to promote the adsorption of target molecules and capture photoexcited electrons to inhibit the recombination of charge pairs, accelerate photoinduced electrons to participate in photocatalytic reaction. In this paper, a series of PCN with rich nitrogen vacancies were prepared by etching of chromic acid solution. Sample 20KCSCN had the highest photocatalytic performance whose evolution efficiency of CO 2 to CO and CH 4 can reach 3.9 and 0.5 μmol·g−1·h−1, respectively. These evolution efficiencies are 2.9 and 4 times higher than that of the PCN. Meanwhile, 20KCSCN demonstrates high CO conversion selectivity and stability. The successful introduction of nitrogen vacancies not only increases the active sites of PCN surface, but also optimizes the optical structure, which dramatically boosts the separation of photoexcited charge pairs and the reduction capacity of photogenerated electrons. The enhancement mechanism for photocatalytic CO 2 reduction performance of PCN was proposed. Besides, photocatalytic H 2 evolution experiments were performed on all samples to confirm the universality of PCN photocatalytic activity enhancement etched by chromic acid solution. H 2 evolution rate on 20KCSCN can reach 652 μmol·g−1·h−1, which is 1.6-fold higher than that on PCN (254 μmol·g−1·h−1) after 4 h irradiation under a 300 W Xe lamp. This work offers new venue for introducing nitrogen vacancies in PCN to regulate photoexcited charge pairs transfer. The photocatalytic enhancement of CO 2 reduction could be used to alleviate the serious issue of excessive CO 2 emission and energy crisis. [ABSTRACT FROM AUTHOR]

The article describes a case of a 16-month-old boy who was diagnosed with infantile onychomycosis and treated with amorolfine nail lacquer.

Background: Identification of promising targeted antigens that exhibited cancer-specific expression is a crucial step in the development of novel antibody-targeted therapies. We here aimed to investigate the anti-tumor activity of a novel monoclonal antibody (mAb) 11C9 and identify the antibody tractable target in the hepatocellular cancer stem cells (HCSCs). Methods: The identification of the targeted antigen was conducted using SDS-PAGE, western blot, mass spectrometry, and co-immunoprecipitation. Silence of HSP90 was induced by siRNA interference. Positive cells were sorted by fluorescence-activated cell sorting. Double-immunofluorescent (IF) staining and two-color flow cytometry detected the co-expression. Self-renewal, invasion, and drug resistance were assessed by sphere formation, matrigel-coated Transwell assay, and CCK-8 assay, respectively. Tumorigenicity was evaluated in mouse xenograft models. RNA-seq and bioinformatics analysis were performed to explore the mechanism of mAb 11C9 and potential targets. Results: MAb 11C9 inhibited invasion and self-renewal abilities of HCC cell lines and reversed the cisplatin resistance. HSP90 (~ 95 kDa) was identified as a targeted antigen of mAb 11C9. Tissue microarrays and online databases revealed that HSP90 was overexpressed in HCC and associated with a poor prognosis. FACS and double-IF staining showed the co-expression of HSP90 and CSCs markers (CD90 and ESA). In vitro and in vivo demonstrated the tumorigenic potentials of HSP90. The inhibition of HSP90 by siRNA interference or 17-AAG inhibitor both decreased the number of invasion, sphere cells, and CD90+ or ESA+ cells, as well as reversed the resistance. Bioinformatics analysis and western blot verified that HSP90 activated Wnt/β-catenin signaling. Conclusions: The study preliminarily revealed the anti-tumor activity of mAb 11C9. More importantly, we identified HSP90 as a targeted antigen of mAb 11C9, which functions as an oncogene in phenotype shaping, stemness maintenance, and therapeutic resistance by activating Wnt/β-catenin signaling. [ABSTRACT FROM AUTHOR]

Most current antidepressants are lacking a pro-cognition effect or even impair cognition as a side effect, and there are few effective psychopharmacological options that improve cognitive dysfunction in depression. Our previous studies revealed that hypidone hydrochloride (YL-0919), a novel 5-HT 1A receptor partial agonist and SSRI, has antidepressant- and anxiolytic-like effects. Here, further studies found that YL-0919, but not vilazodone (a 5-HT 1A receptor partial agonist and SSRI), exerted a significant memory-enhancing effect in the Morris water maze, object recognition test and step-down passive avoidance task. Because the 5-HT 6 receptor has emerged as an interesting drug target to improve cognition, we investigated the target profile of YL-0919 using radioligand binding assays, [ 35 S]-GTPγS binding and cAMP stimulation assays. YL-0919 was found to act as a highly effective, full agonist of 5-HT 6 receptors. Finally, we observed that the memory-enhancing activities of YL-0919 were completely reversed after co-administration of SB271046 (a selective 5-HT 6 receptor antagonist) at a dose that does not alter cognition. In summary, the findings of the current study suggest that YL-0919 has clear memory-enhancing effects, which might be at least partially mediated by 5-HT 6 receptor activation. [ABSTRACT FROM AUTHOR]

The accumulation and storage of maternal mRNA is crucial for oocyte maturation and embryonic development. PATL2 is an oocyte-specific RNA-binding protein, and previous studies have confirmed that PATL2 mutation in humans and knockout mice cause oocyte maturation arrest or embryonic development arrest, respectively. However, the physiological function of PATL2 in the process of oocyte maturation and embryonic development is largely unknown. Here, we report that PATL2 is highly expressed in growing oocytes and couples with EIF4E and CPEB1 to regulate maternal mRNA expression in immature oocytes. The germinal vesicle oocytes from Patl2-/- mice exhibit decreasing maternal mRNA expression and reduced levels of protein synthesis. We further confirmed that PATL2 phosphorylation occurs in the oocyte maturation process and identified the S279 phosphorylation site using phosphoproteomics. We found that the S279D mutation decreased the protein level of PATL2 and led to subfertility in Palt2S279D knock-in mice. Our work reveals the previously unrecognized role of PATL2 in regulating the maternal transcriptome and shows that phosphorylation of PATL2 leads to the regulation of PATL2 protein levels via ubiquitin-mediated proteasomal degradation in oocytes. [ABSTRACT FROM AUTHOR]

Previous studies have investigated the prognostic value of the advanced lung cancer inflammation index (ALI) in gastrointestinal (GI) cancers; however, the results are controversial. This meta-analysis aimed to evaluate the prognostic and clinicopathological role of ALI in patients with GI cancers. A systematic search of electronic databases was conducted to evaluate the prognostic and clinicopathological value of ALI in GI cancers. Nine studies comprising 3,750 patients were included in this meta-analysis. The pooled results showed that a low ALI was significantly associated with worse overall survival (OS, hazard ratio [HR] = 1.95, 95% confidence interval [CI] = 1.53–2.47, P < 0.001, I2 = 63.9%) and disease-free survival/relapse-free survival (DFS/RFS, HR = 1.49, 95% CI = 1.28–1.73, P < 0.001, I2 = 0%) in patients with GI cancers. In addition, decreased ALI correlated with the depth of tumor invasion and presence of distant metastasis and tended to be associated with male sex, high carcinoembryonic antigen levels, lymph node metastasis, and right-sided colon cancer. Low ALI was associated with adverse OS and DFS/RFS in patients with GI cancer. In addition, decreased ALI also correlated with clinicopathological factors, indicating higher stage of the malignancy. [ABSTRACT FROM AUTHOR]

Inspired by the recent experimental progress on the synthesization of a new type of molecule, a polyyne wire doped with the organometallic Ru (dppe) 2 fragment, which exhibits superior electronic properties to similar organic molecules reported before, we studied the electronic transport of it contacted with Au electrodes through first-principles calculations. Multiple striking negative differential resistance (NDR) behavior is observed, where the current could decrease to nearly zero. Moreover, such a phenomenon is found to be robust to the conformational change of the molecule, indicating it is the intrinsic feature of it. Further analysis shows that it is the suppression of the transmission peaks at the border of the bias window that results in the NDR. And, the suppression is resulted from the decay of the local density of states in the two-probe system, especially in the central axis of the molecule, where the states are found to originate from the p orbital of C atoms and the d orbital of Ru atoms. The multiple striking NDR behavior is achieved at the single-molecule level under low bias, showing great application potentials. These findings may throw light on the development of molecular devices. [ABSTRACT FROM AUTHOR]

In this paper we investigate the convergence of Chebyshev type regularization strategy combined with the Morozov discrepancy principle, which is an a posteriori parameter choice rule and independent of the a priori information of exact solution. Compared with the standard Tikhonov regularization method, the Chebyshev type regularization method has no saturation restriction so that its convergence order holds for any υ ≥ 1 2 , where p = 2 υ + 1 2 υ in the H o ̈ l d e r type estimate. [ABSTRACT FROM AUTHOR]

Background: Cancer stem cells (CSCs) are responsible for drug resistance, cancer relapse, and metastasis. Here, we report the first analysis of Palladin expression and its impacts on stem cell‐like properties in lung cancer. Methods: Tissue microarrays were used to investigate Palladin expression and its association with prognosis. Immunofluorescence (IF), flow fluorescence assay, and Western blot were performed to detect Palladin expression in 6 NSCLC cell lines. Cell phenotypes and drug resistance were evaluated. Xenograft models were constructed to confirm the role of Palladin in vivo. Results: By using the tissue microarrays, Palladin was identified to be highly expressed in the cytoplasm, specifically in the cytomembrane of NSCLC, and its high expression is associated with poor prognosis. Palladin is widely expressed and enriched in the sphere cells. The in vitro and in vivo studies showed that Palladin promoted stem cell‐like properties, including cell viability, invasion, migration, self‐renewal abilities, taxol resistance, and tumorigenicity. Western blot revealed that Palladin promoted the accumulation of β‐catenin and activated Wnt/β‐catenin signaling. Tissue microarrays analysis further confirmed the positive correlation between Palladin and β‐catenin. Wnt/β‐catenin pathway inhibitor blocked the Palladin‐induced enhancement of sphere‐forming. Conclusions: Palladin might act as an oncogene by promoting CSCs‐like properties and tumorigenicity of NSCLC cells via the Wnt/β‐catenin signaling pathway. Besides, Palladin was identified to have the potential as a cell surface marker for LCSCs identification. These findings provide a possible target for developing putative agents targeted to LCSCs. [ABSTRACT FROM AUTHOR]