Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation

The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.

Innovative preparation of Co@Cu Fe_(2)O_(4) composite via ball-milling assisted chemical precipitation and annealing for glorious electromagnetic wave absorption

To deal with the growing electromagnetic hazards,herein a Co@CuFe_(2)O_(4)absorbing agent with excellent impedance matching at thin thickness was obtained via an innovative route of ball-milling assisted chemical precipitation and annealing.The as-prepared composite possesses excellent interface polarization ability due to sufficient contact between CuFe_(2)O_(4)NPs and flat Co,and this compressed Co lamella can also provide sufficient eddy current loss.Moreover,the dipole polarization,electron hopping/conduction,and structural scattering also contribute to the broadband microwave absorption of the composite.Thus,the minimum microwave reflection loss achieves-35.56 d B at12.93 GHz for 1.8 mm thickness,and the broadest efficient absorption bandwidth can reach 6.74 GHz for a thinner thickness of 1.72 mm.The preparation method reported here can be referenced as a new-type route to manufacture electromagnetic absorbers with outstanding performance.

Effect of extracellular polymeric substances on Dolichospermum aggregation during temperature rise

Dolichospermum,a typical model filamentous of cyanobacteria,has the potential to cause severely bloom.Extracellular polymeric substances(EPSs)are considered to influence the aggregation of the algae,and temperature is a significant factor affecting EPSs secretion.However,the mechanism of how EPSs affects the aggregation of Dolichospermum is still unclear because the structure and composition of EPSs are complex.In this study,the effects of EPSs on the aggregation of Dolichospermum during the rise of temperature(7-37℃)were determined.The results showed that the concentration of extracellular polysaccharides and proteins changed significantly with increasing temperature(P<0.01).Firstly,during the increasing temperature,the polysaccharide content of EPSs increased from 20.34 to 54.64 mg/L,and the polysaccharides in the soluble EPS(S-EPS)layer changed significantly.The protein content reached maximum value at 21℃(14.52 mg/L)and varied significantly in S-EPS and loosely bound EPS(LB-EPS).In the EPSs matrix,humus substances and protein were main components of S-EPS and LB-EPS,and protein was the main component of tightly bound EPS(TB-EPS).Secondly,the cell density of Dolichospermum increased during the temperature rise while the aggregation ratio decreased.Moreover,zeta potential and surface thermodynamic analysis of Dolichospermum revealed that the interfacial free energy and electrostatic repulsion increased gradually with increasing temperature,which further reduced the aggregation of Dolichospermum.Finally,principal component analysis(PCA)analysis showed the aggregation of Dolichospermum was directly related to the changes of protein in EPSs(especially S-EPS and LB-EPS)and zeta potential,and polysaccharides in EPSs inhibited the aggregation of Dolichospermum.Based on these results,it was illustrated that the composition and concentration of EPSs affected the cell surface properties of Dolichospermum with the change of temperature and thus affected the aggregation of Dolichospermum.

Matrix Metalloproteinase-2,Matrix Metalloproteinase-9,and Transforming Growth Factor Beta 1 Levels in Escherichia coli-Infected Rats with Acute Pyelonephritis

Objective:To investigate the expression of matrix metalloproteinase-2(MMP-2),matrix metalloproteinase-9(MMP-9),and transforming growth factor beta 1(TGF beta 1)in the kidney tissue of rats with pyelonephritis and their relationship with pyelonephritis by establishing a rat model of acute pyelonephritis.Methods:80 male Wistar rats were randomly divided into a control group and an experimental group,with 40 rats each.The rats of the control group were injected with and saline and those of the experimental group were injected with 10μg/mL Escherichia coli(E.coli)and saline(1:100);the solutions for both groups were administered every 3 days for 7 days.The expressions of MMP-2,MMP-9 and TGF beta 1 in the kidney tissues of rats in each group were observed.Results:The expression of MMP-9 and TGF beta 1in the kidney tissue of rat acute pyelonephritis model rats was significantly higher than those of the control group(P<0.01);the MMP-9 mRNA content in the kidney tissue of the experimental group was significantly higher than that of the control group(P<0.05);the TGF beta 1 mRNA content in the renal tissue of the experimental group increased significantly compared to the(P<0.05);MMP-2,MMP-9 and TGF beta 1 began to express in the early stage of pyelonephritis until the complete formation of renal pelvic edema.The difference between groups was statistically significant(P<0.01).Conclusion:MMP-9 and TGF beta 1 are important factors regulating renal tubular epithelial cell injury and inflammatory response.

Exploring the Protective Effect of the Ethanolic Extract of Rosa laevigata Michx.Fruit on Rats with Mesangial Proliferative Glomerulonephritis Based on NLRP3 Inflammasome Pathway

Objective:To investigate the effect of the ethanolic extract of Rosa laevigata Michx.fruit on rats with mesangial proliferative glomerulonephritis based on the NLRP3 inflammasome pathway.Methods:Thirty Wistar rats were divided into three groups,a blank control group,a diabetic nephropathy(DN)model group,and an ethanolic extract intervention group,according to the random number table method,with 10 rats in each group.One day before the experiment,basic feeding was initiated for all the rats;the changes in activity and weight of each group of rats were observed and recorded after 7 d,and a rat model of renal function injury was established after 1 d.Results:Compared with the control group,the model group had significantly higher kidney/body ratio,24 h urine protein,serum creatinine(SCr),blood urea nitrogen(BUN),glomerular mesangial cell(GMC)count,and extracellular matrix(ECM)positive area ratio(P<0.05);the same indicators were significantly lower in the intervention group than in the model group(P<0.05).The NLRP3 inflammasome pathway in renal intrinsic cells was activated in the intervention group.The overactivation of NLRP3 inflammasome is known to promote interleukin(IL)-1βrelease,which was inhibited in the intervention group.Conclusion:The ethanolic extract of Rosa laevigata Michx.fruit has a protective effect on renal intrinsic cells and may be related to NLRP3 inflammasome pathway,suggesting that the fruit of Rosa laevigata Michx.has a potential role in protecting renal intrinsic cells from inflammatory damage.NLRP3 inflammasomes are involved in the development of various chronic inflammatory diseases,such as acute and chronic glomerulonephritis and renal fibrosis.

New Asymptotical Stability and Uniformly Asymptotical Stability Theorems for Nonautonomous Difference Equations

New theorems of asymptotical stability and uniformly asymptotical stability for nonautonomous difference equations are given in this paper. The classical Liapunov asymptotical stability theorem of nonautonomous difference equations relies on the existence of a positive definite Liapunov function that has an indefinitely small upper bound and whose variation along a given nonautonomous difference equations is negative definite. In this paper, we consider the case that the Liapunov function is only positive definite and its variation is semi-negative definite. At these weaker conditions, we put forward a new asymptotical stability theorem of nonautonomous difference equations by adding to extra conditions on the variation. After that, in addition to the hypotheses of our new asymptotical stability theorem, we obtain a new uniformly asymptotical stability theorem of nonautonomous difference equations provided that the Liapunov function has an indefinitely small upper bound. Example is given to verify our results in the last.

Permanence, Periodicity and Extinction of a Delayed Biological System with Stage-Structured Preference for Predator

This study considers a delayed biological system of predator-prey interactions where the predator has stage-structured preference. It is assumed that the prey population has two stages: immature and mature. The predator population has different preference for the stage-structured prey. This type of behavior has been reported in Asecodes hispinarum and Microplitis mediator. By some lemmas and methods of delay differential equation, the conditions for the permanence, existence of positive periodic solution and extinction of the system are obtained. Numerical simulations are presented that illustrate the analytical results as well as demonstrate certain biological phenomena. In particular, overcrowding of the predator does not affect the persistence of the system, but our numerical simulations suggest that overcrowding reduces the density of the predator. Under the assumption that immature prey is easier to capture, our simulations suggest that the predator’s preference for immature prey increases the predator density.

Uniform Persistence, Periodicity and Extinction in a Delayed Biological System with Stage Structure and Density-Dependent Juvenile Birth Rate

A delayed biological system of predator-prey interaction with stage structure and density dependent juvenile birth rate is investigated. It is assumed that the prey population has two stages: immature and mature. The growth of the immature prey is density dependent and is a function of the density of adult prey. Such phenomenon has been reported for beetles, tribolium, copepods, scorpions, several fish species and even crows. The growth of the predator is affected by the time delay due to gestation. By some Lemmas and methods of delay differential equation, the conditions for the uniform persistence and extinction of the system are obtained. Numerical simulations illustrate the feasibility of the main results and demonstrate that the density dependent coefficient has influence on the system populations’ densities though it has no effect on uniform persistence and extinction of the system.

公共话语中的幼儿园教师形象——基于网络媒体新闻的内容分析与话语分析

本研究综合运用内容分析和话语分析的方法,以微信、微博和新闻网站三大媒体平台报道的相关新闻为研究对象,探究公共话语中的幼儿园教师形象。内容分析结果显示,幼儿园教师的公众形象比较负面,并呈现出职业道德低、工作内容技术含量低、个人品质差的"二低一差"特点;社会形象呈现出职业待遇低、学历低、社会地位低的"三低"特点。与中小学教师相比,网络媒介中幼儿园教师形象特征的描述更为负面、具体、多维且充满情绪化。幼儿园教师公众形象的道德特征突出,专业特征则模糊脆弱。话语分析结果显示,网络媒体通过话语的标题主题结构、内容主题结构、措辞和隐含词义以及语境等的运用来构建公众形象,工于幼儿园教师负面形象的塑造而不是正面形象的构建。新闻报道和评论的对比分析表明,网络媒体新闻报道的倾向性和公众评论基本一致,可见媒体对公众认知具有很强的导向作用。网络媒体对幼儿园教师形象进行负面塑造主要源于网络媒体框架定位的负面单一;报道的"短快式"操作;标签化和捆绑式报道。为有效改善公共话语中的幼儿园教师形象,应增强新闻媒体的专业精神和社会责任,着力加强对幼儿园教师专业形象的正面塑造;应积极促进幼儿园教师专业化,利用专业组织的力量主动塑造和维护幼儿园教师的正面形象;应提高公众的媒介素养水平,使其能够理性地看待负面新闻报道,坚持对幼儿园教师群体的正面认识。

农村幼儿园教师工作生活质量对付出—回报失衡感的影响:超负荷的调节作用

为了解农村幼儿园教师付出—回报失衡感的现状及其影响因素,本研究采用分层抽样,对黑龙江省288名农村幼儿园教师进行问卷调查,结果显示农村幼儿园教师的付出—回报失衡感较为严重;工作生活质量的福利待遇、领导管理、休闲生活、教学特性4个因子对农村幼儿园教师付出—回报失衡感有显著的负向预测作用;超负荷在工作生活质量因子对付出—回报失衡感的影响中起调节作用,在超负荷状态下,生活工作质量因子均无法降低农村幼儿园教师的付出—回报失衡感。政府和幼儿园应关注农村幼儿园教师的工作负荷状况,通过释放压力和加强情绪管理等方式避免农村幼儿园教师处于超负荷状态,与此同时应大力转变领导管理理念、改善教师福利待遇、支持教师专业发展、丰富教师休闲文化生活,通过提升农村幼儿园教师的工作生活质量降低其付出—回报失衡感。

家庭媒介生态视角下电子产品使用对幼儿睡眠的影响——基于全国26381个样本的潜在类别分析

良好的睡眠不仅利于幼儿健康体格发展,而且对其大脑发育和心理发展有着重要作用。为了解电子产品使用对幼儿睡眠的影响,本研究对26381名幼儿进行问卷调查与潜在类别分析,结果表明,我国幼儿的睡眠可以分为规范独立、拖延少眠、焦虑抗拒三种类型,分别占33.68%、22.74%、43.58%,总体情况不容乐观。进一步的分析发现,拖延少眠组和焦虑抗拒组的低龄幼儿较多;焦虑抗拒组的男童较多;幼儿电子产品使用的屏幕时间越长,玩电子游戏和观看节目视频的频率越高,越容易出现睡眠问题;家长对电子产品促进幼儿发展的认识不当,幼儿使用电子产品时家长的无效陪伴或陪伴缺失均会导致幼儿出现睡眠问题。家长应理性认识电子产品的教育意义,高度重视家庭媒介生态与幼儿睡眠质量之间的密切联系,通过合理控制屏幕时间、科学使用电子产品、加强有效陪伴等塑造良好家庭媒介环境,改善家长媒介养育行为,准确判断幼儿睡眠类别,实施差异化干预,以此提高并保障幼儿的睡眠质量。

Machine learning for pore-water pressure time-series prediction:Application of recurrent neural networks

Knowledge of pore-water pressure(PWP)variation is fundamental for slope stability.A precise prediction of PWP is difficult due to complex physical mechanisms and in situ natural variability.To explore the applicability and advantages of recurrent neural networks(RNNs)on PWP prediction,three variants of RNNs,i.e.,standard RNN,long short-term memory(LSTM)and gated recurrent unit(GRU)are adopted and compared with a traditional static artificial neural network(ANN),i.e.,multi-layer perceptron(MLP).Measurements of rainfall and PWP of representative piezometers from a fully instrumented natural slope in Hong Kong are used to establish the prediction models.The coefficient of determination(R^2)and root mean square error(RMSE)are used for model evaluations.The influence of input time series length on the model performance is investigated.The results reveal that MLP can provide acceptable performance but is not robust.The uncertainty bounds of RMSE of the MLP model range from 0.24 kPa to 1.12 k Pa for the selected two piezometers.The standard RNN can perform better but the robustness is slightly affected when there are significant time lags between PWP changes and rainfall.The GRU and LSTM models can provide more precise and robust predictions than the standard RNN.The effects of the hidden layer structure and the dropout technique are investigated.The single-layer GRU is accurate enough for PWP prediction,whereas a double-layer GRU brings extra time cost with little accuracy improvement.The dropout technique is essential to overfitting prevention and improvement of accuracy.

Landslide identification using machine learning

Landslide identification is critical for risk assessment and mitigation.This paper proposes a novel machinelearning and deep-learning method to identify natural-terrain landslides using integrated geodatabases.First,landslide-related data are compiled,including topographic data,geological data and rainfall-related data.Then,three integrated geodatabases are established;namely,Recent Landslide Database(Rec LD),Relict Landslide Database(Rel LD)and Joint Landslide Database(JLD).After that,five machine learning and deep learning algorithms,including logistic regression(LR),support vector machine(SVM),random forest(RF),boosting methods and convolutional neural network(CNN),are utilized and evaluated on each database.A case study in Lantau,Hong Kong,is conducted to demonstrate the application of the proposed method.From the results of the case study,CNN achieves an identification accuracy of 92.5%on Rec LD,and outperforms other algorithms due to its strengths in feature extraction and multi dimensional data processing.Boosting methods come second in terms of accuracy,followed by RF,LR and SVM.By using machine learning and deep learning techniques,the proposed landslide identification method shows outstanding robustness and great potential in tackling the landslide identification problem.

Efficient Bayesian networks for slope safety evaluation with large quantity monitoring information

New sensing and wireless technologies generate massive data. This paper proposes an efficient Bayesian network to evaluate the slope safety using large-quantity field monitoring information with underlying physical mechanisms. A Bayesian network for a slope involving correlated material properties and dozens of observational points is constructed.

Uncommon EGFR mutations in a cohort of Chinese NSCLC patients and outcomes of first-line EGFR-TKIs and platinum-based chemotherapy

Objective： Data on the clinical activity of epidermal growth factor receptor （EGFR） tyrosine kinase inhibitors （TKIs） in patients with non-small-cell lung cancer （NSCLC） and uncommon EGFR mutations remain insufficient. This study aimed to investigate the effect of first-line EGFR-TKIs or platinum-based chemotherapy in NSCLC patients with uncommon EGFR mutations. Methods： We retrospectively enrolled 504 patients with EGFR-mutant NSCLC. The clinical characteristics and treatment outcomes were collected and compared between patients with common and uncommon EGFR-mutant NSCLC. Results： Seventy patients （13.9%） harboring uncommon EGFR mutations were included. Thirty of these patients received EGFR-TKIs and 40 received platinum-based chemotherapy as first-line therapy. The objective response rate （ORR） and median progression-free survival （mPFS） of patients treated with TKIs in the uncommon mutation group was significantly inferior to that in the common mutation group （ORR： 23.3% vs. 51.8%, P=0.003; mPFS： 7.1 vs. 10.9 months, P〈0.001）. In the uncommon group, mPFS was similar between first-line EGFR-TKIs treatment and platinum-based chemotherapy （7.1 vs. 6.1 months, P=0.893）. In patients with EGFR G719X or L861Q mutations, the mPFS was longer in the first-line EGFR-TKIs treatment group than in the chemotherapy group, but the difference was not statistically significant （G719X： 8.2 vs. 5.8 months, P=0.061; L861Q： 7.6 vs. 4.1 months, P=0.872）. Multivariate analyses identified adenocarcinoma （P=0.003） as the independent predictive factor for PFS in patients with uncommon EGFR mutations who were treated with first-line EGFR-TKIs. Conclusions： The current study demonstrated that the effect of first-line EGFR-TKIs was similar to that of platinum-based chemotherapy in patients with uncommon EGFR-mutant NSCLC. Adenocarcinoma was the independent predictive factor for PFS in uncommon EGFR-mutant NSCLC patients treated with first-line EGFR- TKIs.

以学生为中心的仪器分析实验线上线下混合式教学探索与实践

针对传统实验教学方法中存在的问题与不足,以仪器分析实验课程为例,提出了以学生为中心的混合式教学设计,通过分层教学满足个性化培养需求。基于大夏学堂在线学习平台,通过线上、线下环环相扣的教学活动有效激发学生的学习兴趣与主动性,引导学生内化知识,培养分析解决问题的高阶思维与综合能力,促进学生全面发展。

Engineering the morphology/porosity of oxygen-doped carbon for sulfur host as lithium-sulfur batteries

Despite the intriguing merits of lithium-sulfur(Li-S) systems, they still suffer from the notorious‘‘shuttling-effect" of polysulfides. Herein, carbon materials with rational tailoring of morphology and pores were designed for strong loading/adsorption with the controlling of energy-storage ability.Through rational tailoring, it is strongly verified that such engineering of evolutions result in variational of sulfur immobilization in the obtained carbon. As expected, the targeted sample delivers a stable capacity of 925 m Ah g^(-1) after 100 loops. Supporting by the "cutting-off" manners, it is disclosed that mesopores in carbon possess more fascinated traits than micro/macropores in improving the utilization of sulfur and restraining Li_(2)S_x(4≤x≤8). Moreover, the long-chain polysulfide could be further consolidated by auto-doping oxygen groups. Supported by in-depth kinetic analysis, it is confirmed that the kinetics of ion/e-transfer during charging and discharging could be accelerated by mesopores, especially in stages of the formation of solid S_(8) and Li_(2)S, further improving the capacity of ion-storage in Li-S battery. Given this, the elaborate study provide significant insights into the effect of pore structure on kinetic performance about Li-storage behaviors in Li-S battery, and give guidance for improving sulfur immobilization.

The influences of biotic and abiotic factors on the occurrence and severity of poplar canker disease in Qingfeng County, China and the management implications

Landscape pathology is a research approach that can provide validation of the effectiveness of regional controls of forest disease at a landscape scale. In this paper, we analyzed the effects of stand features, management approaches, and geographical locations on poplar canker disease incidence （DI） and disease severity index （DSI） of individual trees at a 10 km x 10 km mesoscale landscape in Qingfeng County, China. DI varied significantly with stand age, tree densities, and the degree of canopy closure. DI in stands younger than 4 years old was significantly lower than that in the stands over 6 years old and reached the highest value at a stand age of 8-10 years. Overall, DI was positively correlated with stand age, stand density, andthe degree of canopy closure. DI was significantly lower in agro-forest stand patches than in other three patch types, i.e. isolated patch, pure stand patch, and mixed stand patch. Poplar plantations distributed around and near to villages exhibited significantly higher DI mainly due to human activities and herbivores. Fragmentation or connectivity in this mesoscale landscape seemed not impact disease occurrence. DSI was not significantly correlated with stand density, but varied significantly with tree varieties and trees ages. DSI was highest in stands of 10-12 year trees for all poplar varieties we studied here. Plantation density and plantation age were thus critical factors in determining DI and DSI. A logistic predictive model of disease occurrence was developed for the study area, considering varieties, age, height, density, canopy cover, stand types, patch types, management status, and stand geographical locations. Our study here shows that adjustment of stand density by thinning at different plantation ages is an effective approach controlling the occurrence canker disease in short-rotation poplar plantations at the landscape scale.

Comparative Analyses on Nutritional Ingredients of Two Cultivars of Passion Fruit

The nutritional ingredients of two cultivars of passion fruit （Passiflora edulia Sims）, Zixiang 1 and Pingtang 1 were compared in this study. The results showed that both the two cultivars contained 7 kinds of essential amino acids for humans, and their total content was higher in Pingtang 1. The contents of Ca and K were also higher in Pingtang 1. In addition, passion fruit was rich in vitamin C, vitamin E, protein, dietary fiber and total carbohydrate. On the whole, the nutritional value of Pingtang 1 was higher than that of Zixiang 1, and it can be promoted in largescale cultivation.

Vacuolar invertase genes SbVIN1 and SbVIN2 are differently associated with stem and grain traits in sorghum (Sorghum bicolor)

In higher plants, vacuolar invertases play essential roles in sugar metabolism, organ development, and sink strength. In sorghum(Sorghum bicolor), two vacuolar invertase genes,Sb VIN1(Sobic. 004 G004800) and Sb VIN2(Sobic. 006 G160700) have been reported, but their enzymatic properties and functional differences are largely unknown. We combined molecular, biochemical and genomic approaches to investigate their roles in sorghum stem and grain traits. Sb VIN1 and Sb VIN2 showed different expression levels in internodes,leaves, and panicles, indicating that their importance in each organ was different. In an in vitro sucrose hydrolysis assay, proteins of both genes heterologously expressed in Pichia pastoris displayed similar enzyme properties including the same optimum reaction p H(5)and similar Kmfor sucroe(49 mmol L-1 and 45 mmol L-1 for Sb VIN1 and Sb VIN2,respectively). The optimum reaction temperatures of Sb VIN1 and Sb VIN2 were 45 °C and65 °C, respectively. Sb VIN2 showed higher tolerance to high temperature than Sb VIN1. We characterized the sequence variation of these two vacuolar invertase genes in a panel of 216 diverse inbred lines of sweet and grain sorghum and performed gene-based association analysis. Sb VIN1 showed significant associations with stem traits including stem length,stem diameter, internode number, stem fresh weight, and Brix, as well as grain traits including hundred-grain weight and grain width. Significantly associated variation sites were mainly in 5′ upstream and intron regions. Sb VIN2 only associated with grain width and stem water-soluble carbohydrates(WSCs) content. We conclude that the vacuolar invertase genes Sb VIN1 and Sb VIN2 are differently associated with stem and grain traits in sorghum.