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Graphene possesses not only excellent optical, electrical and thermal properties but also outstanding thermoelectric and photothermal conversion capabilities. The application of graphene with functional responses plays a vital role in the development of intelligent materials intended for flexible actuators and intelligent robots. Cellulose paper is foldable and is a hydrophilic network comprised of porous cellulose fibres. In this paper, graphene composites as well as cellulose paper were taken as basic materials, which were further combined with other polymer materials (biaxially oriented polypropylene film (BOPP) and poly (3, 4-ethylenedioxythiophene/polystyrene sulfonate) (PEDOT: PSS). PEDOT: PSS solution can penetrate into the porous network of the paper to form a high-strength nanocomposite structure. A flexible thin film driver capable of multiple stimuli under light, heat and humidity was produced. Through characterization, it was found that the bending ability of the composite film was significantly improved in response to stimulation.

The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulphite and sodium silicate, respectively, as a single depressant and their mixture as a combined depressant. Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant (more than 80%) within the studied dosage range. Galena flotation was severely depressed with descending depressing order as follows: combined depressant - sodium silicate - sodium sulphite. Electrochemical analysis confirmed the high affinity of depressants on the galena surface, resulting in the formation of hydrophilic species, such as lead sulphite, lead sulphate, and lead orthosilicate. The oxidation of chalcopyrite surface and depressants did not exhibit any signals; conversely, the self-oxidation of chalcopyrite was depressed. The results of cyclic voltammograms agreed well with the flotation results, demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants., The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulphite and sodium silicate, respectively, as a single depressant and their mixture as a combined depressant. Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant (more than 80%) within the studied dosage range. Galena flotation was severely depressed with descending depressing order as follows: combined depressant - sodium silicate - sodium sulphite. Electrochemical analysis confirmed the high affinity of depressants on the galena surface, resulting in the formation of hydrophilic species, such as lead sulphite, lead sulphate, and lead orthosilicate. The oxidation of chalcopyrite surface and depressants did not exhibit any signals; conversely, the self-oxidation of chalcopyrite was depressed. The results of cyclic voltammograms agreed well with the flotation results, demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.

This study investigated the effects of H2O2 treatment on xanthate interaction and flotation separation of chalcopyrite and pyrite by making use of a series of laboratory flotation experiments and surface analysis techniques. Flotation test results showed that H2O2 treatment influenced the flotation behaviours of the two minerals; however, flotation of pyrite was depressed more significantly than that of the chalcopyrite. Under well-controlled H2O2 concentration, the selective separation of chalcopyrite from pyrite was realised at pH 9.0, at which the recovery of chalcopyrite was over 84% and that of pyrite was less than 24%. Zeta potential, UV-visible and IR spectrum measurements revealed that the collector interacted differently with the two minerals after H2O2 treatment, and the surface of chalcopyrite adsorbed a much greater amount of xanthate than that of the pyrite. IR and XPS analyses showed that the H2O2 treatment significantly changed the surface properties of pyrite to a very hydrophilic species that inhibited the adsorption of collector and thus depressed the floatability of pyrite. While, the surface of chalcopyrite remained mildly inert to H2O2, as a result, the adsorption of xanthate and its oxidation to dixanthogen were very effective, which enhanced the flotation of chalcopyrite., This study investigated the effects of H2O2 treatment on xanthate interaction and flotation separation of chalcopyrite and pyrite by making use of a series of laboratory flotation experiments and surface analysis techniques. Flotation test results showed that H2O2 treatment influenced the flotation behaviours of the two minerals; however, flotation of pyrite was depressed more significantly than that of the chalcopyrite. Under well-controlled H2O2 concentration, the selective separation of chalcopyrite from pyrite was realised at pH 9.0, at which the recovery of chalcopyrite was over 84% and that of pyrite was less than 24%. Zeta potential, UV-visible and IR spectrum measurements revealed that the collector interacted differently with the two minerals after H2O2 treatment, and the surface of chalcopyrite adsorbed a much greater amount of xanthate than that of the pyrite. IR and XPS analyses showed that the H2O2 treatment significantly changed the surface properties of pyrite to a very hydrophilic species that inhibited the adsorption of collector and thus depressed the floatability of pyrite. While, the surface of chalcopyrite remained mildly inert to H2O2, as a result, the adsorption of xanthate and its oxidation to dixanthogen were very effective, which enhanced the flotation of chalcopyrite.

Multilayer networked systems are ubiquitous in nature and engineering, and the robustness of these systems against failures is of great interest. A main line of theoretical pursuit has been percolation induced cascading failures, where interdependence between network layers is conveniently and tacitly assumed to be symmetric. In the real world, interdependent interactions are generally asymmetric. To uncover and quantify the impact of asymmetry in interdependence on network robustness, we focus on percolation dynamics in double-layer systems and implement the following failure mechanism: once a node in a network layer fails, the damage it can cause depends not only on its position in the layer but also on the position of its counterpart neighbor in the other layer. We find that the characteristics of the percolation transition depend on the degree of asymmetry, where the striking phenomenon of a switch in the nature of the phase transition from first- to second-order arises. We derive a theory to calculate the percolation transition points in both network layers, as well as the transition switching point, with strong numerical support from synthetic and empirical networks. Not only does our work shed light upon the factors that determine the robustness of multilayer networks against cascading failures, but it also provides a scenario by which the system can be designed or controlled to reach a desirable level of resilience., Comment: 20 pages, 7 figures

An optimal single-photon source should deterministically deliver one and only one photon at a time, with no trade-off between the source’s efficiency and the photon indistinguishability. However, all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering which reduced the efficiency by 50%, which fundamentally limited the scaling of photonic quantum technologies. Here, we overcome this final long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities—two examples are narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation-collection scheme is designed to minimize the polarization-filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60±0.02 (0.56±0.02), a single-photon purity of 0.975±0.005 (0.991±0.003), and an indistinguishability of 0.975±0.006 (0.951± 0.005) for the micropillar (Bragg grating) device. Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.

Water vapor feedbacks on different time scales are investigated using radiative kernels applied to the Atmospheric Infrared Sounder and Microwave Limb Sounder satellite observations, as well as the Coupled Model Intercomparison Project Phase 5 model simulation results. We show that the magnitude of short-term global water vapor feedback based on observed interannual variations from 2004 to 2016 is 1.55 ± 0.23 W m−2 K−1, while model-simulated results derived from the Coupled Model Intercomparison Project Phase 5 runs driven by observed sea surface temperature range from 0.99 to 1.75 W m−2 K−1, with a multimodel mean of 1.40 W m−2 K−1. The long-term water vapor feedbacks derived from the quadrupling of CO2 runs range from 1.47 to 2.03 W m−2 K−1, higher than the short-term counterparts. The systematic difference between short-term and long-term water vapor feedbacks illustrates that care should be taken when inferring long-term feedbacks from interannual variabilities. Also, the magnitudes of the short-term and long-term feedbacks are closely correlated (R = 0.66) across the models, implying that the observed short-term water vapor feedback could be used to constrain the simulated long-term water vapor feedback. Based on satellite observations, the inferred long-term water vapor feedback is about 1.85 ± 0.32 W m−2 K−1. ©2018. American Geophysical Union. All Rights Reserved.

Run Liu,1,* Bi-Xia Liu,2,* Mingyue Ma,1,* Dan Kong,3,* Guanglin Li,4 Junle Yang,1 Xiaoping Wu,1 Jiyong Zheng,3 Yan Dong1 1Department of Radiology, The Affiliated Xi’an Central Hospital of Xi’an Jiaotong University, Xi’an, 710004 Shaanxi, People’s Republic of China; 2Department of ICU, Jiangxi Provincial Cancer Hospital, Nanchang, 330029 Jiangxi, People’s Republic of China; 3Department of Medical Imaging, The Affiliated Huaian No. 1 People’s Hospital of Nanjing Medical University, Huaian, 223300 Jiangsu, People’s Republic of China; 4Honghui Hospital, Xi’an Jiaotong University, Xi’an, 710054 Shaanxi, People’s Republic of China *These authors contributed equally to this work Objective: To identify whether the amplitude of low-frequency fluctuations (ALFF) analysis has the potential to serve as a biological marker to detect alcohol-induced spontaneous brain activities and distinguish the patients with alcohol dependence from the healthy subjects. Methods: We utilized the ALFF analysis to report on the alcohol-induced spontaneous brain activities in 29 patients with alcohol dependence (9 female, 20 male) relative to 29 status-matched healthy subjects (11 female, 18 male). Receiver operating characteristic curve was used to test the ability of the ALFF analysis in discriminating the patients with alcohol dependence from the healthy subjects. Pearson correlation was used to evaluate the relationships between the signal value of those ALFF differences in brain areas and behavioral characteristics. Results: Alcohol-induced brain differences located in the right inferior parietal lobule and right supplementary motor area with significant higher ALFF values, and in the left precuneus and bilateral cerebellum posterior lobe with lower ALFF values. The movement-related areas were significantly correlated with each other (P<0.05). Receiver operating characteristic curve reve

The global mean precipitation is largely constrained by atmospheric radiative cooling rates (Qr), which are sensitive to changes in high cloud fraction. We investigate variations of high cloud fraction with surface temperature (Ts) from July 2002 to June 2015 and compute their radiative effects on Qr using the Fu-Liou-Gu plane-parallel radiation model. We find that the tropical mean (30°S-30°N) high cloud fraction decreases with increasing Ts at a rate of about -1.0 ± 0.34% K-1 from 2002 to 2015, which leads to an enhanced atmospheric cooling around 0.86 W m-2 K-1. On the other hand, the northern midlatitudes (30°N-60°N) high cloud fraction increases with surface warming at a rate of 1.85 ± 0.65% K-1 and the near-global mean (60°S-60°N) high cloud fraction shows a statistically insignificant decreasing trend with increasing Ts over the analysis period. Dividing high clouds into cirrus, cirrostratus, and deep convective clouds, we find that cirrus cloud fraction increases with surface warming at a rate of 0.32 ± 0.11% K-1 (0.01 ± 0.17% K-1) for the near-global mean (tropical mean), while cirrostratus and deep convective clouds decrease with surface warming at a rate of -0.02 ± 0.18% K-1 and -0.33 ± 0.18% K-1 for the near-global mean and -0.64 ± 0.23% K-1 and -0.37 ± 0.13% K-1 for the tropical mean, respectively. High cloud fraction response to feedback to Ts accounts for approximately 1.9 ± 0.7% and 16.0 ± 6.1% of the increase in precipitation per unit surface warming over the period of 2002-2015 for the near-global mean and the tropical mean, respectively. © 2017. American Geophysical Union. All Rights Reserved.

Pengcheng Liu,1,2,* Xing Wu,1,* Hui Shi,1,2 Run Liu,1 Hexi Shu,1 JinPeng Gong,1 Yong Yang,1 Qi Sun,1 Jiezhou Wu,1,2 Xiaoyang Nie,1 Ming Cai1 1Department of Orthopedics, Shanghai Tenth People’s Hospital, Tongji University, School of Medicine, Shanghai, 2First Clinical Medical College, Nanjing Medical University, Nanjing, People’s Republic of China *These authors contributed equally to this work Background: Intramedullary and extramedullary fixation methods are used in the management of subtrochanteric femur fractures. However, whether intramedullary or extramedullary fixation is the primary treatment for subtrochanteric femur fractures in adults remains debatable.Level of evidence: Meta-analyses of prospective studies, level I.Materials and methods: The Cochrane library, Embase, Google Scholar, and PubMed databases were searched separately for all relevant studies published before January 1, 2015. No language restriction was applied. Prospective randomized controlled trials that compared intramedullary or extramedullary internal fixation to repair subtrochanteric femur fractures in adults were included. We determined intraoperative data, postoperative complications, fracture fixation complications, wound infection, hospital stay days, and final outcome measures to assess the relative effects of different internal fixation methods for the treatment of subtrochanteric femur fractures in adults.Results: Six studies were included in our meta-analysis. The relative risks (RRs) of revision rate was 83% lower (RR, 0.17, 95% confidence interval [CI], 0.05 to 0.60; P=0.006), fixation failure rate was 64% lower (RR, 0.36, 95% CI, 0.12 to 1.08; P=0.07), non-union rate was 77% lower (RR, 0.23, 95% CI, 0.07 to 0.81; P=0.02) in the intramedullary group compared with the extramedullary group. No significant differences were found between the intramedullary group and extramedullary group for intraoperative data, postoperative complications, wound infection, hospi

Kuan Liu,* Pengcheng Liu,* Run Liu, Xing Wu, Ming Cai Department of Orthopaedics, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, People’s Republic of China *These authors contributed equally to this work Purpose: To investigate the effectiveness and safety of epidural steroid injections in patients with lumbar spinal stenosis (LSS). Methods: We performed a search on the CENTRAL, Pubmed, Embase and Cochrane databases up to September 2014. We recovered 17 original articles, of which only 10 were in full compliance with the randomized controlled trial (RCT) criteria. These articles were reviewed in an independent and blinded way by two reviewers who were previously trained to extract data and score their quality by the criteria of the Cochrane Handbook (5.1.0). Results: We accepted ten studies with 1,010 participants. There is minimal evidence that shows that epidural steroid injections are better than lidocaine alone, regardless of the mode of epidural injection. There is a fair short-term and long-term benefit for treating spinal stenosis with local anesthetic and steroids. Conclusions: This meta-analysis suggests that epidural steroid injections provide limited improvement in short-term and long-term benefits in LSS patients. Keywords: lumbar spinal stenosis, epidural injection, steroid, local anesthetic, chronic painA Letter to the Editor has been received and published for this article

The sensing mechanism of a fluoride colorimetric chemosensor 4-(tert-butyldimethylsilyloxy)-Nbutyl- naphthalimide has been studied with density functional theory and time-dependent density functional theory methods. The theoretical results suggest that the low barrier of the desilylation reaction is responsible for the rapid response speed to the fluoride anion of the chemosensor. The calculated vertical excitation energies in the ground state of the chemosensor and its desilylation product agree well with the experimental UV-Vis absorbance spectra. It is also found that the intramolecular charge transfer process of the first excited state of the desilylation product induces the redshift of the absorbance and fluorescence spectra of the desilylation product compared with that of the chemosensor. Further, the previously experimentally incorrect assignment of the 11H NMR spectrum of the desilylation product has been rectified in the present theoretical study.

The sensing mechanism of a fluoride colorimetric chemosensor 4-(tert-butyldimethylsilyloxy)-Nbutyl- naphthalimide has been studied with density functional theory and time-dependent density functional theory methods. The theoretical results suggest that the low barrier of the desilylation reaction is responsible for the rapid response speed to the fluoride anion of the chemosensor. The calculated vertical excitation energies in the ground state of the chemosensor and its desilylation product agree well with the experimental UV-Vis absorbance spectra. It is also found that the intramolecular charge transfer process of the first excited state of the desilylation product induces the redshift of the absorbance and fluorescence spectra of the desilylation product compared with that of the chemosensor. Further, the previously experimentally incorrect assignment of the 11H NMR spectrum of the desilylation product has been rectified in the present theoretical study.

In this Letter, we introduce an aspiration-induced reconnection mechanism into the spatial public goods game. A player will reconnect to a randomly chosen player if its payoff acquired from the group centered on the neighbor does not exceed the aspiration level. We find that an intermediate aspiration level can best promote cooperation. This optimal phenomenon can be explained by a negative feedback effect, namely, a moderate level of reconnection induced by the intermediate aspiration level induces can change the downfall of cooperators, and then facilitate the fast spreading of cooperation. While insufficient reconnection and excessive reconnection induced by low and high aspiration levels respectively are not conductive to such an effect. Moreover, we find that the intermediate aspiration level can lead to the heterogeneous distribution of degree, which will be beneficial to the evolution of cooperation., Comment: 6 pages, 5 figures

In this paper, based on a weighted projection of a bipartite user-object network, we introduce a personalized recommendation algorithm, called network-based inference (NBI), which has higher accuracy than the classical algorithm, namely collaborative filtering. In NBI, the correlation resulting from a specific attribute may be repeatedly counted in the cumulative recommendations from different objects. By considering the higher order correlations, we design an improved algorithm that can, to some extent, eliminate the redundant correlations. We test our algorithm on two benchmark data sets, MovieLens and Netflix. Compared with NBI, the algorithmic accuracy, measured by the ranking score, can be further improved by 23 per cent for MovieLens and 22 per cent for Netflix. The present algorithm can even outperform the Latent Dirichlet Allocation algorithm, which requires much longer computational time. Furthermore, most previous studies considered the algorithmic accuracy only; in this paper, we argue that the diversity and popularity, as two significant criteria of algorithmic performance, should also be taken into account. With more or less the same accuracy, an algorithm giving higher diversity and lower popularity is more favorable. Numerical results show that the present algorithm can outperform the standard one simultaneously in all five adopted metrics: lower ranking score and higher precision for accuracy, larger Hamming distance and lower intra-similarity for diversity, as well as smaller average degree for popularity.

n this Brief Report, we propose an index of user similarity, namely, the transferring similarity, which involves all high-order similarities between users. Accordingly, we design a modified collaborative filtering algorithm, which provides remarkably higher accurate predictions than the standard collaborative filtering. More interestingly, we find that the algorithmic performance will approach its optimal value when the parameter, contained in the definition of transferring similarity, gets close to its critical value, before which the series expansion of transferring similarity is convergent and after which it is divergent. Our study is complementary to the one reported in [E. A. Leicht, P. Holme, and M. E. J. Newman, Phys. Rev. E 73, 026120 (2006)], and is relevant to the missing link prediction problem.

In this paper, we propose a novel method to compute the similarity between congeneric nodes in bipartite networks. Different from the standard cosine similarity, we take into account the influence of a node’s degree. Substituting this new definition of similarity for the standard cosine similarity, we propose a modified collaborative filtering (MCF). Based on a benchmark database, we demonstrate the great improvement of algorithmic accuracy for both user-based MCF and object-based MCF.

The floatability was studied of galena in wastewater samples from different mineral processing operations at the Fankou, China, Pb-Zn mine. The results showed that residual collector molecules in wastewater from the thickening of Pb and Zn concentrates had a beneficial effect on the formation of lead xanthanate on the surface of the galena. However, some chemical components in the wastewater from the Zn tailings and effluent resulted in surface reactions occurring on the galena, and direct re-use of this water may have an adverse effect on flotation., The floatability was studied of galena in wastewater samples from different mineral processing operations at the Fankou, China, Pb-Zn mine. The results showed that residual collector molecules in wastewater from the thickening of Pb and Zn concentrates had a beneficial effect on the formation of lead xanthanate on the surface of the galena. However, some chemical components in the wastewater from the Zn tailings and effluent resulted in surface reactions occurring on the galena, and direct re-use of this water may have an adverse effect on flotation.

A novel mixed collector (BHOA) was prepared by mixing benzohydroxamic acid (BHA) and sodium oleate (NaOL) and applied to the flotation separation of smithsonite from dolomite. Flotation results showed that NaOL alone had good collecting performance on smithsonite and common gangue mineral dolomite but had poor selectivity. By using a BHA/NaOL mixed system with a molar ratio of 2:1, the recoveries of smithsonite and dolomite reached approximately 90% and 5%, respectively. Surface tension analysis showed that the surface activity of BHOA was a little higher than that of a single NaOL because of synergistic effects. Zeta potential and X-ray photoelectron spectroscopy measurements indicated that surfactants BHA and NaOL co-absorbed on the smithsonite surface and only NaOL was present on the dolomite surface in the presence of BHOA. (Authors.), A novel mixed collector (BHOA) was prepared by mixing benzohydroxamic acid (BHA) and sodium oleate (NaOL) and applied to the flotation separation of smithsonite from dolomite. Flotation results showed that NaOL alone had good collecting performance on smithsonite and common gangue mineral dolomite but had poor selectivity. By using a BHA/NaOL mixed system with a molar ratio of 2:1, the recoveries of smithsonite and dolomite reached approximately 90% and 5%, respectively. Surface tension analysis showed that the surface activity of BHOA was a little higher than that of a single NaOL because of synergistic effects. Zeta potential and X-ray photoelectron spectroscopy measurements indicated that surfactants BHA and NaOL co-absorbed on the smithsonite surface and only NaOL was present on the dolomite surface in the presence of BHOA. (Authors.)

Flotation tests were carried out using the organic mercapto compound DMPS as depressant for the separation of Cu-activated marmatite from pyrrhotite in the presence of butyl xanthate. Single mineral tests showed that DMPS has a strong depressing effect on pyrrhotite in the absence and presence of Cu ions but has an activating effect on marmatite in the presence of Cu ions. The floatability of marmatite improved in the pH range 2-12. The results of tests on mineral mixtures showed that Cu- activated marmatite can be separated efficiently from pyrrhotite using DMPS. The molecular structure of DMPS contains functional groups such as - SH and -SO3, and xanthate and DMPS compete for adsorption on sulphide minerals., Flotation tests were carried out using the organic mercapto compound DMPS as depressant for the separation of Cu-activated marmatite from pyrrhotite in the presence of butyl xanthate. Single mineral tests showed that DMPS has a strong depressing effect on pyrrhotite in the absence and presence of Cu ions but has an activating effect on marmatite in the presence of Cu ions. The floatability of marmatite improved in the pH range 2-12. The results of tests on mineral mixtures showed that Cu- activated marmatite can be separated efficiently from pyrrhotite using DMPS. The molecular structure of DMPS contains functional groups such as - SH and -SO3, and xanthate and DMPS compete for adsorption on sulphide minerals.

Results are presented which show that the organic compound DMPS, which has a number of different functional groups such as -SH and -SO3, is a good depressant for pyrrhotite but has hardly any effect on jamesonite. Xanthate and DMPS compete to absorb sulphide minerals. DMPS carries several hydrophilic functional groups which render the surface of pyrrhotite more hydrophilic, resulting in the depressant action., Results are presented which show that the organic compound DMPS, which has a number of different functional groups such as -SH and -SO3, is a good depressant for pyrrhotite but has hardly any effect on jamesonite. Xanthate and DMPS compete to absorb sulphide minerals. DMPS carries several hydrophilic functional groups which render the surface of pyrrhotite more hydrophilic, resulting in the depressant action.

Bubble size measurements were conducted and the attachment behaviour studied between bubbles and particles using sphalerite samples in a high-intensity conditioning (HIC) cell and a flotation cell. The results showed that high intensity conditioning created a favourable environment for the formation of small bubbles due to hydrodynamic cavitation. The fine bubbles have a high probability of bubble-particle collision, which enhances fine particle flotation. The attachment experiments indicated that many fine bubbles are produced in situ on the surface of fine particles, and most of the particles are aggregated as a result of the bridging action of the bubbles. Observation of bubble-particle interactions in the flotation cell showed that aggregates created by HIC can be loaded more easily by large air bubbles than those created by normal conditioning., Bubble size measurements were conducted and the attachment behaviour studied between bubbles and particles using sphalerite samples in a high-intensity conditioning (HIC) cell and a flotation cell. The results showed that high intensity conditioning created a favourable environment for the formation of small bubbles due to hydrodynamic cavitation. The fine bubbles have a high probability of bubble-particle collision, which enhances fine particle flotation. The attachment experiments indicated that many fine bubbles are produced in situ on the surface of fine particles, and most of the particles are aggregated as a result of the bridging action of the bubbles. Observation of bubble-particle interactions in the flotation cell showed that aggregates created by HIC can be loaded more easily by large air bubbles than those created by normal conditioning.

With butyl xanthate as collector, the flotation behaviours of jamesonite, pyrrhotite and marmatite were studied as well as the depressant effects of mercaptoacetic acid or mercaptoethanol and the effect of Cu2+ ion on depression. The minerals were found hard to separate, jamesonite and pyrrhotite having good flotability in the pH range 2-10 and marmatite good flotability in acid. Separation was possible when the depressants were used in the pH range 6-8 but not in the presence of Cu2+ ion. Infrared spectroscopy demonstrated the functional groups involved in the interactions, including hydrophilic -COOH and -OH groups on the depressants that make the surfaces of pyrrhotite and marmatite more hydrophilic., With butyl xanthate as collector, the flotation behaviours of jamesonite, pyrrhotite and marmatite were studied as well as the depressant effects of mercaptoacetic acid or mercaptoethanol and the effect of Cu2+ ion on depression. The minerals were found hard to separate, jamesonite and pyrrhotite having good flotability in the pH range 2-10 and marmatite good flotability in acid. Separation was possible when the depressants were used in the pH range 6-8 but not in the presence of Cu2+ ion. Infrared spectroscopy demonstrated the functional groups involved in the interactions, including hydrophilic -COOH and -OH groups on the depressants that make the surfaces of pyrrhotite and marmatite more hydrophilic.

Selective flotation has been used to recover sulphide minerals before oxidised ones in a refractory oxidised lead ore from Tibet. OBF, a self-developed collector, and ammonium dibutyl dithiophosphate were used to collect cerussite and galena, sodium silicate was used to depress silicate gangues, and mercaptobenzothiazole was introduced to intensify silver recovery. The closed-circuit flotation test resulted in a galena concentrate grading 50.03% Pb and a cerussite concentrate grading 34.50% Pb with the total Pb recovery up to 73.10%. The silver grade of the galena concentrate stayed at 10 576.22 g/t with a corresponding 66.52% recovery., Selective flotation has been used to recover sulphide minerals before oxidised ones in a refractory oxidised lead ore from Tibet. OBF, a self-developed collector, and ammonium dibutyl dithiophosphate were used to collect cerussite and galena, sodium silicate was used to depress silicate gangues, and mercaptobenzothiazole was introduced to intensify silver recovery. The closed-circuit flotation test resulted in a galena concentrate grading 50.03% Pb and a cerussite concentrate grading 34.50% Pb with the total Pb recovery up to 73.10%. The silver grade of the galena concentrate stayed at 10 576.22 g/t with a corresponding 66.52% recovery.

The pre-concentration was studied of low-grade stone coal from Shanxi, China, using desliming and flotation. The ore contained 0.68 wt% V2O5, 1.14 wt% Fe, 2.98 wt% CaO, 0.56 wt% S, 75.72 wt% SiO2, 0.46 wt% P2O5, 2.63 wt% BaO and 3.77 wt% Al2O3. The V in the stone coal occurred as muscovite or in Fe-Al oxides and the major gangue minerals were quartz, calcite and barite. Slime with a V2O5 grade and recovery of 2.30% and 45.90%, respectively, was obtained using a two-stage desliming process involving the addition of 2 000 g/t of sodium silicate to the pulp at a solid/liquid ratio of 1:3 and stirring for 15 minutes at 500 rpm, followed by the addition of 1 000 g/t of sodium silicate to the pulp. Two-stage flotation experiments were carried out using reverse flotation to float calcite, with the tailings further subjected to direct flotation. Optimum calcite flotation parameters were grinding to a fineness of less than 3 mm, pH 7-6 and the use 2 000 g/t of water glass as depressant and 200 g/t of oleic acid as collector. Selective separation of V-bearing minerals was achieved by flotation in acidic solution using the melamine cationic collector EA.A final vanadium concentrate with V2O5 grade and recovery of 1.88% and 76.58% was obtained, with 72.51% of the raw ore rejected as tailings. The pre-concentration process increased the V2O5 grade and lowered the content of acid consuming minerals, reducing the subsequent metallurgical V extraction process costs., The pre-concentration was studied of low-grade stone coal from Shanxi, China, using desliming and flotation. The ore contained 0.68 wt% V2O5, 1.14 wt% Fe, 2.98 wt% CaO, 0.56 wt% S, 75.72 wt% SiO2, 0.46 wt% P2O5, 2.63 wt% BaO and 3.77 wt% Al2O3. The V in the stone coal occurred as muscovite or in Fe-Al oxides and the major gangue minerals were quartz, calcite and barite. Slime with a V2O5 grade and recovery of 2.30% and 45.90%, respectively, was obtained using a two-stage desliming process involving the addition of 2 000 g/t of sodium silicate to the pulp at a solid/liquid ratio of 1:3 and stirring for 15 minutes at 500 rpm, followed by the addition of 1 000 g/t of sodium silicate to the pulp. Two-stage flotation experiments were carried out using reverse flotation to float calcite, with the tailings further subjected to direct flotation. Optimum calcite flotation parameters were grinding to a fineness of less than 3 mm, pH 7-6 and the use 2 000 g/t of water glass as depressant and 200 g/t of oleic acid as collector. Selective separation of V-bearing minerals was achieved by flotation in acidic solution using the melamine cationic collector EA.A final vanadium concentrate with V2O5 grade and recovery of 1.88% and 76.58% was obtained, with 72.51% of the raw ore rejected as tailings. The pre-concentration process increased the V2O5 grade and lowered the content of acid consuming minerals, reducing the subsequent metallurgical V extraction process costs.

The flotation of powellite (CaMo)4) and apatite was investigated in the presence of sodium oleate. The results showed that sodium oleate exhibited good flotation performance for both minerals. Powellite and apatite showed similar behaviour under alkaline conditions, and recovery of the two minerals was more than 80%. Sodium hexametaphosphate reduced the recovery of powellite and apatite to varying degrees, and at a dosage of 220 mg/l the recoveries of the two minerals were 62.5% and 20.3%, respectively. Sodium oleate significantly increased the work of adhesion of the grains of both minerals, facilitating their absorption by bubbles. Sodium hexametaphosphate increased the difference in hydrophobicity between the minerals, optimising their separation. The adsorption mechanism of sodium oleate on the two minerals involved chemisorption., The flotation of powellite (CaMo)4) and apatite was investigated in the presence of sodium oleate. The results showed that sodium oleate exhibited good flotation performance for both minerals. Powellite and apatite showed similar behaviour under alkaline conditions, and recovery of the two minerals was more than 80%. Sodium hexametaphosphate reduced the recovery of powellite and apatite to varying degrees, and at a dosage of 220 mg/l the recoveries of the two minerals were 62.5% and 20.3%, respectively. Sodium oleate significantly increased the work of adhesion of the grains of both minerals, facilitating their absorption by bubbles. Sodium hexametaphosphate increased the difference in hydrophobicity between the minerals, optimising their separation. The adsorption mechanism of sodium oleate on the two minerals involved chemisorption.

The processing was studied of a low-grade ore containing 0.12% Cu, 0.66% Pb, 1.88% Zn, 0.41 g/t Au, 11.81 g/t Ag, 23.62% Fe and 14.20% S by bulk flotation of Cu-Pb followed by separation of Cu and Pb. A combined depressant consisting of Na2Cr2O7, Na2S2O5, carboxymethyl cellulose and Na2SiO3 was used for the flotation separation of Cu and Pb to produce a Cu concentrate with a grade and recovery of 16.61% and 64.14%, respectively, and a Pb concentrate with a grade and recovery of 43.57% and 79.54%. The main advantage of the process is the substantially reduced pollution from the use of dichromate., The processing was studied of a low-grade ore containing 0.12% Cu, 0.66% Pb, 1.88% Zn, 0.41 g/t Au, 11.81 g/t Ag, 23.62% Fe and 14.20% S by bulk flotation of Cu-Pb followed by separation of Cu and Pb. A combined depressant consisting of Na2Cr2O7, Na2S2O5, carboxymethyl cellulose and Na2SiO3 was used for the flotation separation of Cu and Pb to produce a Cu concentrate with a grade and recovery of 16.61% and 64.14%, respectively, and a Pb concentrate with a grade and recovery of 43.57% and 79.54%. The main advantage of the process is the substantially reduced pollution from the use of dichromate.

In this paper, based on a weighted projection of a bipartite user-object network, we introduce a personalized recommendation algorithm, called network-based inference (NBI), which has higher accuracy than the classical algorithm, namely collaborative filtering. In NBI, the correlation resulting from a specific attribute may be repeatedly counted in the cumulative recommendations from different objects. By considering the higher order correlations, we design an improved algorithm that can, to some extent, eliminate the redundant correlations. We test our algorithm on two benchmark data sets, MovieLens and Netflix. Compared with NBI, the algorithmic accuracy, measured by the ranking score, can be further improved by 23 per cent for MovieLens and 22 per cent for Netflix. The present algorithm can even outperform the Latent Dirichlet Allocation algorithm, which requires much longer computational time. Furthermore, most previous studies considered the algorithmic accuracy only; in this paper, we argue that the diversity and popularity, as two significant criteria of algorithmic performance, should also be taken into account. With more or less the same accuracy, an algorithm giving higher diversity and lower popularity is more favorable. Numerical results show that the present algorithm can outperform the standard one simultaneously in all five adopted metrics: lower ranking score and higher precision for accuracy, larger Hamming distance and lower intra-similarity for diversity, as well as smaller average degree for popularity.

n this Brief Report, we propose an index of user similarity, namely, the transferring similarity, which involves all high-order similarities between users. Accordingly, we design a modified collaborative filtering algorithm, which provides remarkably higher accurate predictions than the standard collaborative filtering. More interestingly, we find that the algorithmic performance will approach its optimal value when the parameter, contained in the definition of transferring similarity, gets close to its critical value, before which the series expansion of transferring similarity is convergent and after which it is divergent. Our study is complementary to the one reported in [E. A. Leicht, P. Holme, and M. E. J. Newman, Phys. Rev. E 73, 026120 (2006)], and is relevant to the missing link prediction problem.

In this paper, we propose a novel method to compute the similarity between congeneric nodes in bipartite networks. Different from the standard cosine similarity, we take into account the influence of a node’s degree. Substituting this new definition of similarity for the standard cosine similarity, we propose a modified collaborative filtering (MCF). Based on a benchmark database, we demonstrate the great improvement of algorithmic accuracy for both user-based MCF and object-based MCF.