•A model for describing arsenic (As) impurity behavior during the antimony (Sb) metal purified by vacuum volatilization was established.•Behaviors of As impurity in the residue and volatile of Sb ...metal present an exponential decrease.•This model can quantitatively predict As impurity concentration in the purified Sb metal.
This paper proposes a straightforward model that can describe the arsenic(As) impurity behavior during the vacuum volatilization purification process of antimony (Sb) metal. This model aims to determine the optimal degree of volatilization and predict As impurity concentration in the purified Sb metal. Vacuum volatilization experiments were conducted to verify this model at the volatilization temperatures of 700 °C, 730 °C, and 760 °C. The research results indicated that, the concentrations of As impurity in both residue and volatile exhibit an exponentially decreasing trend throughout the entire volatilization process; the decrease in the condensing temperature at the different locations of volatiles leads to an increase in As impurity concentration, which is accompanied by the variations in crystal morphology; there is a good agreement between the calculated and experimental results in the residues, which the mean standard deviations are ± 0.025, ±0.094, and ± 0.148 respectively at the above volatilization temperatures; the calculated results are much higher than the experimental results in the volatiles due to the calculated separation coefficient without the consideration of kinetic factor; the optimal volatilization degrees of 36.50 %, 35.95 %, and 38.44 % respectively result in volatilization removal rates and residual rates both exceeding 60 %; Upon the volatilization degrees are equal to 36.94 %, 30.28 %, and 47.09 %, As impurity decreases from the initial concentrations of 27.82 mg/kg, 22.90 mg/kg, and 35.08 mg/kg to the ultimate concentrations of 10 mg/kg respectively, which meets the purity standard of 4.5 N (99.995 %). Consequently, this model can quantitatively predict As impurity concentration in the purified Sb metal, which provides the theoretical guidance for the As removal from Sb metal by vacuum volatilization.
The development of a new strategy for the construction of chiral cyclic sulfide-containing multiple stereogenic centers is highly desirable. Herein, by the combination of base-promoted ...retro-sulfa-Michael addition and palladium-catalyzed asymmetric allenylic alkylation, the streamlined synthesis of chiral thiochromanones containing two central chiralities (including a quaternary stereogenic center) and an axial chirality (allene unit) was successfully realized with up to 98% yield, 49.0 : 1 dr and >99% ee.
The development of a new strategy for the construction of chiral cyclic sulfide-containing multiple stereogenic centers is highly desirable.
An attempt has been made in this paper to examine the effect of particle size on flotation parameters in the separation of diaspore and kaolinite. First of all, the basic properties such as zeta ...potential and contact angle and flotation behaviors of diaspore and kaolinite in sodium oleate (NaOL) and dodecylamine (DDA) solution were investigated. And then direct and reverse flotation experiments of mixed binary minerals at different size fractions were carried out. The classical first order flotation kinetics were used to fit the flotation data and first-order rate constant (k), ultimate recovery (R∞), modified rate constant (Km), selectivity index (SI) and separation efficiency (SE) were calculated and used as the flotation parameters to evaluate the separation effect of the two minerals. The results show that in the separation of diaspore and kaolinite, the particle size has a significant influence on the flotation parameters. The favorable particle size fractions for direct flotation were −38+20μm and −54+38μm and the adverse particle size fractions were −10μm and −20+10μm. While for reverse flotation, the favorable particle size fractions were −74+54μm and −10μm and the adverse particle size fractions were −38+20μm and −54+38μm. The optimal flotation times for the favorable size fractions were shorter than that for unfavorable size fractions. For the same size fractions, longer flotation times were required to reach the maximum separation efficiency in reverse flotation than those in direct flotation. Under the optimized condition (direct flotation, pH=10, NaOL dosage was 2×10−4mol/L, ore particle size was −38+20μm), concentrate products with diaspore recovery of 83.79% and A/S value of 7.96 can be obtained.
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•The separation of diaspore and kaolinite were evaluated by several parameters.•Optimal size fractions of direct and reverse were investigated.•Optimum flotation times of direct and reverse flotation were compared.•Optimum flotation times for different size fraction particles are different.
In order to overcome the unsatisfactory stability drawback of titanium-based PbO2-coated anodes used in electrochemical oxidation treatments of refractory organic wastewater, a novel PbO2-coated ...anode obtained by introducing a tungsten carbide (WC) modified manganese dioxide composite coating (MnO2-WC) via anodic co-deposition in a MnSO4 solution mixed with WC particles as an intermediate is fabricated (Ti/MnO2-WC/β-PbO2). Characterization measurements including scanning electronic microscopy accompanied by energy dispersive X-rays, X-ray diffraction, and X-ray photoelectron spectroscopy are used to analyze the microstructure and chemical composition of the coated anode, including the interlayer coating and superficial coating. The electrochemical and electrocatalytic properties of the interlayer and anode surfaces are analyzed using linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy. Meanwhile, the failure mechanism of the anode coated with the MnO2-WC composite interlayer, and the life-extension mechanism due to introducing the composited interlayer, are determined via accelerated-life tests and a comprehensive failure analysis of the tested samples. The results show that, compared with MnO2, the conductivity of the MnO2-WC interlayer is greatly improved and exhibits higher oxygen evolution potential as well as better electrocatalytic activity. The anodic β-PbO2 grains deposited on the MnO2-WC interlayer surface become finer, more compact and homogeneous. The MnO2-WC composite interlayer increases the number of surface active sites and promotes the electro-crystallization process of the PbO2 surface coatings, which results in thicker PbO2 coatings. As a result, the Ti/MnO2-WC/β-PbO2-coated anode shows better electrocatalytic activity and superior stability in this work, and its accelerated life is more than twice that of Ti/β-PbO2 anodes.
The Bayes classification rule offers the optimal classifier, minimizing the classification error rate, whereas the Neyman–Pearson lemma offers the optimal family of classifiers to maximize the ...detection rate for any given false alarm rate. These motivate studies on comparing classifiers based on similarities between the classifiers and the optimal. In this article, we define partial order relations on classifiers and families of classifiers, based on rankings of rate function values and rankings of test function values, respectively. Each partial order relation provides a sufficient condition, which yields better classification error rates or better performance on the receiver operating characteristic analysis. Various examples and applications of the partial order theorems are discussed to provide comparisons of classifiers and families of classifiers, including the comparison of cross-validation methods, training data that contains outliers, and labelling errors in training data.
Alors que la classification bayésienne minimise le taux de mauvaises classifications, ce qui en fait un classificateur optimal, le lemme de Neyman-Pearson offre un classificateur optimal maximisant le taux de détection pour un taux de fausses alarmes fixé. Cette remarque motive des études comparant les classificateurs. L’auteur définit une relation d’ordre partiel sur les classificateurs et les familles de classificateurs basée sur les rangs des valeurs des fonctions de taux et des fonctions de tests. Chaque relation d’ordre partiel mène à une condition suffisante qui conduit à de meilleurs taux de classification ou à une performance accrue pour l’analyse des courbes ROC. L’auteur discute plusieurs exemples et applications des théorèmes d’ordre partiel afin de fournir des comparaisons entre des classificateurs et des familles de classificateurs, notamment la comparaison de méthodes de validation croisée, des données d’apprentissage comportant des valeurs aberrantes, et des erreurs d’étiquettes dans les données d’apprentissage.
The α7-human papillomavirus (HPV)-related cervical squamous cell carcinoma (SCC) is associated with poor prognosis. We compared the genomic profiles of this disease in a cohort corresponding to the ...2001-2014 period with various responses to radiotherapy or concurrent chemoradiation through microRNA (miR) profiling involving miR 4.0 array and human transcriptome array 2.0 analyses. A real-time quantitative polymerase chain reaction was then conducted to identify the predictive biomarkers. A significantly lower expression of miR143-3p in recurrent tumors (
= 0.0309) relative to that in nonrecurrent tumors was observed. The miR143-3p targeted the mRNA expression of the baculoviral inhibitor of the apoptosis protein (IAP) repeat-containing 2 (BIRC2;
= 0.0261). The BIRC2 protein levels (
= 0.0023) were significantly higher in recurrent tumors than in nonrecurrent tumors. Moreover, the miR-143-3p sensitized the response of α7-HPV-related cervical SCC to chemotherapy by targeting
. A combination of
-inhibitor LCL161 and topotecan exerted synergistic effects on cancer cells and animal tumor models. In a pooled cohort of α7-HPV-related cervical SCC (including mixed infections with non-α7-HPV) treated between 1993 and 2014, high
expression was associated with significantly worse outcomes (cancer-specific survival, hazard ratio (HR) = 1.42,
= 0.008; progression-free survival, HR = 1.64;
= 0.005). Summarily, BIRC2 constitutes a novel prognostic factor and therapeutic target for α7-HPV-related cervical SCC.
Replication fork reversal which restrains DNA replication progression is an important protective mechanism in response to replication stress. PARP1 is recruited to stalled forks to restrain DNA ...replication. However, PARP1 has no helicase activity, and the mechanism through which PARP1 participates in DNA replication restraint remains unclear. Here, we found novel protein-protein interactions between PARP1 and DNA translocases, including HLTF, SHPRH, ZRANB3, and SMARCAL1, with HLTF showing the strongest interaction among these DNA translocases. Although HLTF and SHPRH share structural and functional similarity, it remains unclear whether SHPRH contains DNA translocase activity. We further identified the ability of SHPRH to restrain DNA replication upon replication stress, indicating that SHPRH itself could be a DNA translocase or a helper to facilitate DNA translocation. Although hydroxyurea (HU) and MMS induce different types of replication stress, they both induce common DNA replication restraint mechanisms independent of intra-S phase activation. Our results suggest that the PARP1 facilitates DNA translocase recruitment to damaged forks, preventing fork collapse and facilitating DNA repair.
Green manure cover crops (GMCCs) planting has a potential for mitigating greenhouse gas emissions (GHG) in agroecosystems and provides important ecosystem services, thereby achieving the Sustainable ...Development Goals (SDGs) stipulated by the United Nations. However, the advantages of cultivating GMCCs on arable land are not widely recognized. For example, in the whole of China, the GMCCs planting area is less than 3.5% of total arable land. The aim of this study is to explore reasons for the low adoption rate of GMCCs planting. Using best–worst scaling (BWS) approach, farmers ranked their preferred conservation practices including three types of GMCC cropping systems. Taking Gansu Province in Northwest China as a case study, a survey with 276 farmers was conducted. The findings indicated that three factors are related to the low adoption rate of GMCCs: 1) farmers preferred improving farmland irrigation facilities and substituting chemical fertilizers with organic rather than planting GMCCs; 2) lack of awareness and understanding of government policy on GMCCs and limited access to training courses; 3) financial support and subsidies from the government are insufficient. This study provides insights and strategic implications for policymakers on how to further promote GMCCs in the future.
We develop and study adaptive rate scheduling mechanisms over cellular wireless networks, as used for the unicast provision of video streams to client mobiles at variable quality of experience (QoE) ...levels. Under service type I, mobile users receive video streams at a QoE level that is not lower than a specified value. In addition, mobile users that experience sufficiently high communications channel quality levels may be provided video streams at higher video quality levels. Under service type II, mobile clients receive their video streams at QoE levels that are based on their recorded signal to noise and interference levels. Resource allocations among mobiles are, however, subjected to absolute and proportional fairness objectives. We employ a proxy video manager and resource controller that is located at (or associated with) the base station node. The manager intercepts a channel quality indicator message reported by a mobile client, using it to determine the QoE level at which a requested video stream will be provided. It then selects the proper source and channel encoding schemes to be used for producing and transmitting a compressed version of the stream. To regulate inter-cell signal interference, we examine the joint employment of a number of different spectral-reuse and fractional frequency reuse (FFR) scheduling schemes. To illustrate the use of our models to configure system parameters, we consider a performance metric that incorporates a will-to-pay utility function. We develop analytical techniques for the modeling, analyzing, and designing of such systems. We confirm the precision of these models through the conduct of simulation analyses. Also, we show that, under certain system configurations, FFR-based schemes can lead to substantial enhancement of the system's performance behavior.
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