Mechanistic insights into stepwise activation of malachite for enhancing surface reactivity and flotation performance

Malachite is a common copper oxide mineral that is often enriched using the sulfidization-xanthate flotation method.Currently,the direct sulfidization method cannot yield copper concentrate products.Therefore,a new sulfidization flotation process was developed to promote the efficient recovery of malachite.In this study,Cu^(2+) was used as an activator to interact with the sample surface and increase its reaction sites,thereby strengthening the mineral sulfidization process and reactivity.Compared to single copper ion activation,the flota-tion effect of malachite significantly increased after stepwise Cu^(2+) activation.Zeta potential,X-ray photoelectron spectroscopy(XPS),time-of-flight secondary ion mass spectroscopy(ToF-SIMS),scanning electron microscopy and energy dispersive spectrometry(SEM-EDS),and atomic force microscopy(AFM)analysis results indicated that the adsorption of S species was significantly enhanced on the mineral surface due to the increase in active Cu sites after Cu^(2+) stepwise activation.Meanwhile,the proportion of active Cu-S spe-cies also increased,further improving the reaction between the sample surface and subsequent collectors.Fourier-transform infrared spec-troscopy(FT-IR)and contact angle tests implied that the xanthate species were easily and stably adsorbed onto the mineral surface after Cu^(2+) stepwise activation,thereby improving the hydrophobicity of the mineral surface.Therefore,the copper sites on the malachite sur-face after Cu^(2+) stepwise activation promote the reactivity of the mineral surface and enhance sulfidization flotation of malachite.

Ladder Time Stepwise Inertia Coordinated Control Method of Multiple Wind Farms to Suppress System Frequency Secondary Drop

Currently,both regulated and deregulated power trading exist in China’s power system,which has caused imbalanced funds in the electricity market.In this paper,a simulation analysis of the electricity market with wind energy resources is conducted,and the calculation methods of unbalanced funds are investigated systematically.In detail,the calculation formulas of unbalanced funds are illustrated based on their definition,and a two-track electricity market clearing model is established.Firstly,the concept of the dual-track system is explained,and the specific calculation formulas of various types of unbalanced funds are provided.Next,considering the renewable energy consumption,the market clearing model based on DC power flow is constructed and solved;by combining fitting methods of mid-and long-term curves,the unbalanced funds are calculated based on clearing results and formulas.

Effect of early stepwise cardiopulmonary rehabilitation on function and quality of life in sepsis patients

BACKGROUND Sepsis,as a non-limiting host infection disease,can be accompanied by serious complications such as organ failure,which seriously threatens patient quality of life.AIM To investigate the effect of early stepwise cardiopulmonary rehabilitation on cardiopulmonary function and quality of life in patients evacuated from mechanical ventilation with sepsis.METHODS A total of 80 patients with sepsis who were hospitalized in our hospital from January 2021 to January 2022 were selected and divided into the observation group(n=40)and the control group(n=40)according to the random number table method.The observation group was treated with early stepwise cardiopulmonary rehabilitation,and the control group was treated with a conventional treatment regimen.Cardiac function indexes(central venous pressure,cardiac troponin I,B-type brain natriuretic peptide),lung function indicators(diaphragmatic mobility,changes in central venous oxygen saturation,oxygenation index),and quality of life(Quality of Life Evaluation Scale)were compared between the two groups after treatment.RESULTS After treatment,the central venous pressure,diaphragm mobility,central venous oxygen saturation,oxygenation index,and Quality of Life Evaluation Scale scores in the observation group were higher than those in the control group,and the differences were statistically significant(P<0.05).The observation group was less than that of the control group for other parameters,and the differences were statistically significant(P<0.05).CONCLUSION Early stepwise cardiopulmonary rehabilitation can effectively enhance cardiac and pulmonary function and improve the quality of life in patients evacuated from mechanical ventilation with sepsis.

Cost-benefit and discriminant validity of a stepwise dementia case-finding approach in an Asian older adult community

Background Case-finding is a recommended approach for dementia early detection in the community.Aims To investigate the discriminant validity and cost-effectiveness of a stepwise dementia case-finding approach in a Singaporean older adult community.Methods The two-phase study was conducted in the community from 2009 to 2015 in Singapore.A total of 3780 participants(age≥60 years)completed phase I(a brief cognitive screening);918 completed phase II and were included in the final analysis.In phase I,all participants were administered the Abbreviated Mental Test(AMT)and the Progressive Forgetfulness Question(PFQ).Those who screened positive on either test were invited to phase II,whereby the Mini-Mental State Examination(MMSE),Montreal Cognitive Assessment(MoCA)and a formal neuropsychological battery were administered,followed by the research diagnosis of no cognitive impairment,cognitive impairment no dementia(CIND)-Mild(≤2 impaired cognitive domains),CIND-Moderate(>2 impaired domains)or dementia.Receiver operating characteristic curve analyses were conducted for the different cognitive instruments.All discriminant indices were calculated,including sensitivity,specificity,positive and negative predictive values(NPV)and accuracy.Cost-effectiveness analysis was conducted by estimating the amount of screening time needed and the number of older adults requiring re-evaluation in two case-finding scenarios,ie,with or without preselection by the PFQ.Results The stepwise case-finding approach(preselection by the PFQ,then MMSE or MoCA or AMT)showed an excellent NPV(>99%)and accuracy(>86%)for excluding dementia-free cases.Without preselection by the PFQ,screening time for the three cognitive tools were 317.5,317.5 and 254 hours,with 159,302 and 175 screen-positive older adults involved in further evaluation.By adopting the stepwise case-finding approach,total screening time were 156.5,156.5 and 126.2 hours,which decreased by 50.7%,50.7% and 50.3% as compared with those without preselection.Furthermore,after preselection,only 98,167 and 145 screen-positive older adults required further evaluation,corresponding to a reduction of 38.4%,44.7% and 17.1% in the numbers compared with those without preselection.Conclusions A stepwise approach for dementia case-finding should be implemented in the community to minimise the time and resources needed for large-scale early detection of dementia.

Application of cluster analysis and stepwise regression in predicting the traffic volume of lanes

Because of the difficulty to obtain the traffic flow information of lanes at non-detector intersections in most metropolises of the world,based on the relationships between the lanes of signal-controlled intersections,cluster analysis and stepwise regression are integrated to predict the traffic volume of lanes at non-detector isolated controlled intersections.First cluster analysis is used to cluster the lanes of non-detector isolated signal-controlled intersections and the lanes of all signal-controlled intersections with detectors.Then, by the results of cluster analysis,the traffic volume samples are selected randomly and stepwise regression is used to predict the traffic volume of lanes at non-detector isolated signal-controlled intersections.The method is tested by the traffic volume data of lanes of the road network of Nanjing city.The problem of predicting the traffic volume of lanes at non-detector isolated signal-controlled intersections was resolved and can be widely used in urban traffic flow guidance and urban traffic control in cities without enough intersections equipped with detectors.

Population Quantity Variations of Oriental Fruit Fly (Bactrocera dorsalis Hendel) on the Basis of Stepwise Regression Analysis

[Objective] The research aimed to study the significant influence factors of the population variations of oriental fruit fly. [Method] Using stepwise regression analysis, the population variations law of oriental fruit fly in Jianshui County of Yunnan province and the meteorological factors that caused its occurrence were analyzed. And the regression model was built. Finally, the regression model was tested on the basis of the data in Jianshui County of Yunnan Province during 2004-2006.[Result] The main meteorological factors that influenced the occurrence of oriental fruit fly were relative humidity, the lowest monthly temperature and rainfall. [Conclusion] This study will provide certain reference for the prediction researches on the time, quantity and occurrence peak of oriental fruit fly.

基于STEPWISE框架下《畜牧学》课程教学设计探讨

教学设计是教育改革和教师实施教学的一项核心内容。《畜牧学》是一门多学科交叉、多技能融合的课程。文章根据《畜牧学》课程在教学中存在的问题,按照STEPWISE框架教学理念,提出《畜牧学》课程设计思路,期望学生通过《畜牧学》课程学习,能够发现整理畜牧生产中存在的或潜在的问题,提出探究项目和研究思路,制定研究计划并开展项目研究。鼓励大学生参与课题项目研究,创新教学,促进实践,解决生产问题,提高畜牧科技教育,促进个人、社会和环境的健康发展。

Study on QSAR of Taxol and its Derivatives Based on Stepwise Multivariate Linear Regression Analysis

Abstract Using the method of stepwise multivariate linear regression (SMLR), the quantitative structure activity relationships (QSAR) of two isomeric series of taxol and its derivatives have been studied. It was found that the molar refractivity of the C3′substituent of the C13 side chain has significant correlation with its activity. We deduce that structural changes in the C3′substituents may be critical to the anticancer function. It would be useful to the design and synthesis of taxol like compounds with improved activities.

乳腺癌术后患者自我形象的Stepwise多元回归分析调查

目的探讨乳腺癌术后患者自我形象水平的影响因素。方法选择我院2018年9月至2019年9月接收的70例乳腺癌术后患者以及同期70例健康女性作为研究对象,应用自我形象量表(BIBCQ)评分,分析乳腺癌术后患者自我形象的相关因素,并采用多元线性回归分析,确定影响患者自我形象的独立因素。结果乳腺癌术后患者自我形象各维度评分明显高于健康女性(P<0.001),Stepwise多元线性回归分析显示,年龄、配偶态度、文化程度、抑郁焦虑是乳腺癌术后自我形象的独立影响因素。结论乳腺癌患者术后自我形象受配偶态度、年龄、文化程度等多种因素影响,临床应针对相关影响因素实施个性化护理服务。

Characterizing and estimating rice brown spot disease severity using stepwise regression,principal component regression and partial least-square regression

Detecting plant health conditions plays a key role in farm pest management and crop protection. In this study, measurement of hyperspectral leaf reflectance in rice crop (Oryzasativa L.) was conducted on groups of healthy and infected leaves by the fungus Bipolaris oryzae (Helminthosporium oryzae Breda. de Hann) through the wavelength range from 350 to 2 500 nm. The percentage of leaf surface lesions was estimated and defined as the disease severity. Statistical methods like multiple stepwise regression, principal component analysis and partial least-square regression were utilized to calculate and estimate the disease severity of rice brown spot at the leaf level. Our results revealed that multiple stepwise linear regressions could efficiently estimate disease severity with three wavebands in seven steps. The root mean square errors (RMSEs) for training (n=210) and testing (n=53) dataset were 6.5% and 5.8%, respectively. Principal component analysis showed that the first principal component could explain approximately 80% of the variance of the original hyperspectral reflectance. The regression model with the first two principal components predicted a disease severity with RMSEs of 16.3% and 13.9% for the training and testing dataset, respec-tively. Partial least-square regression with seven extracted factors could most effectively predict disease severity compared with other statistical methods with RMSEs of 4.1% and 2.0% for the training and testing dataset, respectively. Our research demon-strates that it is feasible to estimate the disease severity of rice brown spot using hyperspectral reflectance data at the leaf level.

THE STEPWISE EXCHANGE ACTION AND STERIC HINDRANCE EFFECT OF ORGANIC PHENOLS ON CLAYS IN SEAWATER

The exchange action of six types of organic phenols on clay surfaces in seawater is systematically studied in this work. The following significant conclusions are drawn from the experiments. (1) The interaction of organic phenols with montmorillonite, illite and kaolinite in seawater is monovalent anion exchage.(2) Their isotherms of stepwise exchage on clay surfaces belong to the Langmuir type or stepwise type.(3) The discovery of the"steric hindrance effects of stepwise exchange of organic phenols on clays surfaces", and revelation of an exchange mechanisrn diffeient from that in references are the greatest achieverments in this work.

Stepwise multiple regressions application in liposome orthogonal experiments

Aim New statistical method was applied in data analysis of orthogonal experiments to optimize the preparation of liposome. Method Particle size, zeta potential, encapsulation efficiency and physical stability of liposomes were selected by orthogonal design as evaluating indicators. Through three statistical methods （direct observation, variance analysis and stepwise multiple regression）, the optimized preparing conditions were acquired and validated by experiment. Results All of the four indicators were different by these analyses. The validation experiments indicated that the optimized conditions by stepwise multiple regressions were better than that by traditional analysis. Conclusion Experiment results suggested that multiple regressions could avoid the weakness of direct observation and variance analysis, but more work should be done in preparing liposomes.

Even-parity states of the Sm atom with stepwise excitation

Two-colour stepwise excitation and photoionization schemes are adopted to study the spectra of high-lying states of the Sm atom. These bound even-parity states are excited with three different excitation paths from the 4f66s6p7DJ （J = 1, 2, 3） intermediate states, respectively. They are probed by photoionization process with an extra photon driving them to the continuum states. In this experiment, 270 states are detected in an energy range from 36160 cm-1 to 42250 cm-1, 109 of which are newly discovered, while the rest of them are confirmed to be the energy levels reported previously. Furthermore, based on the J-momentum selection rules of three excitation paths, a unique assignment of J-momentum for all observed states is determined, eliminating all remaining ambiguities in the literature. Finally, 53 single-colour transitions originating from the scanning laser are also identified. For all the relevant transitions, the information about their relative intensities is also given in the paper.

Principles and technology for stepwise utilization of resources for mitigating deep mine heat hazards

As is well known, deep mines are hot. As mining depth increases, the temperature of the surrounding rock also increases. This seriously affects mine safety and production and has restricted the exploitation of deep coal resources. Therefore, reducing the working face temperature to improve working conditions by controlling these heat hazards is an urgent problem. Considering problems in cooling deep mines both domestically and abroad along with the actual conditions of the Zhangshuanglou coal mine, we propose a HEMS technology that uses heat resources from deep mines in a stepwise manner. HEMS means a high temperature ex-change machinery system. Mine inrush-water is used as a source of cooling. Twice the energy is extracted from the mine inrush water. Heat is used for building heating in the winter and cold water is used for cooling buildings in the summer. This opens a new technology for stepwise utilization of heat energy in deep mines. Energy conservation and reduced pollution, an improved environment and sustainable economic development are realized by this technique. The economic and social effects are obvious and illustrate a good prospect for the application and extension of the method.

Stepwise inversion method for determining anisotropy parameters in a horizontal transversely isotropic formation

The anisotropy of a geologic formation can reflect the direction of fractures and ground stress, which is an important metric that guides the exploration and development of oil and gas reservoirs. Cross-dipole acoustic logging is the main method used to detect anisotropy with borehole geophysics. In this paper, a stepwise inversion method for three anisotropy parameters in a horizontal transversely isotropic(HTI) formation is proposed, which turns one 3D operation of simultaneous inversion into three 1D operations. The scheme’s stability and reliability were tested by numerically simulated data using a f inite-difference method, and by f ield logging data. The inversion results of the simulated data show that the stepwise inversion method can stably obtain the fast shear azimuth and the anisotropy parameters in both fast and slow formations with strong and weak anisotropy, and it performed well even with noisy data. In particular, the results of the fast shear azimuth inversion were very stable and reliable. The inversion results of f ield logging data were consistent with those given by existing commercial software, which used simultaneous inversion, for both fast and slow formations. Where large difference was observed between our stepwise method and the commercial software, our analysis suggests that the fast shear azimuth of our inversion was more reasonable, which reinforces its superior performance and practicality.

An optimized protocol for stepwise optimization of real-time RT-PCR analysis

Computational tool-assisted primer design for real-time reverse transcription(RT)PCR(qPCR)analysis largely ignores the sequence similarities between sequences of homologous genes in a plant genome.It can lead to false confidence in the quality of the designed primers,which sometimes results in skipping the optimization steps for qPCR.However,the optimization of qPCR parameters plays an essential role in the efficiency,specificity,and sensitivity of each gene’s primers.Here,we proposed an optimized approach to sequentially optimizing primer sequences,annealing temperatures,primer concentrations,and cDNA concentration range for each reference(and target)gene.Our approach started with a sequence-specific primer design that should be based on the single-nucleotide polymorphisms(SNPs)present in all the homologous sequences for each of the reference(and target)genes under study.By combining the efficiency calibrated and standard curve methods with the 2−ΔΔCt method,the standard cDNA concentration curve with a logarithmic scale was obtained for each primer pair for each gene.As a result,an R 2≥0.9999 and the efficiency(E)=100±5% should be achieved for the best primer pair of each gene,which serve as the prerequisite for using the 2^(−ΔΔCt) method for data analysis.We applied our newly developed approach to identify the best reference genes in different tissues and at various inflorescence developmental stages of Tripidium ravennae,an ornamental and biomass grass,and validated their utility under varying abiotic stress conditions.We also applied this approach to test the expression stability of six reference genes in soybean under biotic stress treatment with Xanthomonas axonopodis pv.glycines(Xag).Thus,these case studies demonstrated the effectiveness of our optimized protocol for qPCR analysis.

Establishment Method of Shape Standard Curve Based on Stepwise Optimization and Its Compensation Models

There are very few researches on the shape standard curve currently,and they merely remain on the level of description of the general concept and production experiences,lacking of the in-depth theoretical analysis,and the concrete principle,method and steps for determining the shape standard curve are not put forward,therefore,they are not applicable in industrial production.This is the weakest spot in the research on the basic shape theory.In this paper,the basic shape standard curve and the transverse distribution curve of the exit thickness are attained with stepwise optimization,which is based on the theoretical calculation method of the shape standard curve of strip mills proposed by authors.By calculating the shape discrimination model and the shape forecast model separately,the simultaneous iterative calculation by the previous method is avoided,and the speed and stability of calculation are improved.The compensation models of the transverse temperature difference of the strip,the shape detection roller deflection and the shape of the strip coil are established,respectively,meantime,the basic shape standard curves are compensated,and the relatively perfect theoretical establishment method of the shape standard curve is formed.The simulation and calculation are done on a 1 220 mm five-stand cold strip tandem mill.The simulation and calculation result shows that the principle,method and steps for determining the shape standard curve are correct and feasible,and the correctness of theoretical analysis and calculation is verified.This paper proposes an idea and a method for the establishment of the shape standard curve in the rolling processes of cold strip mills,which develop the theory and model of the shape standard curve and improve the quality and efficiency of the shape control in the rolling processes of cold strip mills.

TAYLOR POLYNOMIAL STEPWISE REFINEMENTALGORITHM FOR LIE AND HIGH SYMMETRIES OF PARTIAL DIFFERENTIAL EQUATIONS

In this article, based on the Taylor expansions of generating functions and stepwise refinement procedure, authors suggest a algorithm for finding the Lie and high (generalized) symmetries of partial differential equations (PDEs). This algorithm transforms the problem having to solve over-determining PDEs commonly encountered and difficulty part in standard methods into one solving to algebraic equations to which one easy obtain solution. so, it reduces significantly the difficulties of the problem and raise computing efficiency. The whole procedure of the algorithm is carried out automatically by using any computer algebra system. In general, this algorithm can yields many more important symmetries for PDEs.

Multi－variate Stepwise Discriminant Analysis Research Affecting Portal Hypertension＇s Grade Factors of Liver Function

The idtal time for selecting portal hypertension operation is the accurate judgement of the grade of liver function.yet the present criterion in grading liver functicn is controversial.tco pztitnts vith 20 factoxs related to poxttl hypeitersor wexe undergone stepwise discriminant analysis by using SAS software on the IBM/PC computer(significance levtl α=0.05).The results show that ascites degree prothrombin tmie(PT),serum total bilirubin,serum albumin content,main portal vein flow are significant fators.In the light of above variates contributing to grading liver function as to estblish a discriminant eqation,it was found that the total agreement rate between replaceable discimination and original Child-Pugh classification is 86%.A test for agieement was performed between discriminant and original classificaton,showing that the two kinds of classification methods have a good agreement rates (Kppa=0.7856),indicating the discriminant classification is of practica values.

Occurrences of Excess ^(40)Ar in Hydrothermal Tourmaline: Interpretations from ^(40)Ar-^(39)Ar Dating Results by Stepwise Heating

The occurrences of excess ^40Ar within a hydrothermal tourmaline is discussed in term of the analysis data of syngenetic muscovite and tourmaline from the Lushui hydrothermal tin-tungsten deposit in western Yunnan, China, using the ^40Ar-^39Ar stepwise heating technique. About 80% excess ^40 Ar was released in the last step when the tourmaline was fused, corresponding to a release of only -3% ^39 Ar （K）, which indicates that most excess ^40 Ar was held in the mineral lattice rather than in the channels parallel to the Z-axis. This suggests that the excess ^40 Ar was incorporated during crystallization and not diffused into the tourmaline during the post-crystallization history.