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    Wyświetlanie 1-21 z 21
    Tytuł:
    Flocculation/dispersion of hematite with caustic digested starch
    Autorzy:
    Tang, M.
    Wen, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/109542.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    starch
    alkali-digestion
    flocculation
    dispersion
    Opis:
    Selective flocculation of hematite with starch is a process well-known in practice. However, the separation of hematite from other minerals depends strongly on the methods of starch digestion performed either as heating-digestion or alkali-digestion (different type and dosage of alkali). The purpose of this study is to identify possible influence of the alkali-digested starch on flocculation of ultra-fine hematite when the starch was digested at different concentrations of sodium hydroxide at room temperature. Adsorption of starch digested with sodium hydroxide at different concentration on hematite was investigated by abstraction and co-precipitation tests. Turbidities tests, settling rates, flocculation/dispersion measurement and Fourier transform infrared spectroscopic analysis (FTIR) have also been conducted. Based on the results of the above mentioned tests it is suggested that the flocculating power of caustic digested starch towards fine particles may be significantly weakened, while its dispersing ability starts to play a role instead, if the concentration of sodium hydroxide is high enough in starch digestion. When the weight ratio of NaOH /starch is lower than 2, incomplete gelatinization of starch granules may lead to coagulation of fine particles of hematite mostly due to non-selective electrostatic attraction. The weight ratio of NaOH /starch from 2 to 4 helps to flocculate mineral surfaces selectively and efficiently, assuring a complete digestion of starch granules and a small amount of acidic functional products on the starch chain. However, much smaller and homogenous short-chain granules resulting from higher concentration of sodium hydroxide (the weight ratio of NaOH /starch is more than 4) used to digest starch may weaken the flocculating capacity of the caustized starch for hematite and lead to its dispersion.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 2; 477-489
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Caustic-digested starch and its adsorption on hematite
    Autorzy:
    Tang, M.
    Wen, S.
    Tong, X.
    Powiązania:
    https://bibliotekanauki.pl/articles/110383.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    starch
    digestion
    alkali
    carboxylic group
    Opis:
    Adsorption characteristics on hematite of caustic-digested starch by sodium hydroxide or potassium hydroxide were investigated through a series of tests, like adsorption tests, paste titration and zeta potentials measurement, scanning electron microscope measurement (SEM) and Fourier transform infrared spectroscopic analysis (FTIR) as well. An attempt was made in order to identify the possible effects of starch digested with alkali at different concentrations on its adsorption on mineral surfaces. All results pointed out that a different amount of carboxyl groups in the starch gel were harvested from alkali-digestion as a function of concentrations of sodium hydroxide or potassium hydroxide; more acidic groups were produced if higher concentrations of alkali were added. These carboxyl groups may contribute the acid/base interaction of the caustic-digested starch on hematite. Also, different concentrations of sodium hydroxide to digest starch seem to induce different degrees of its gelatinization from the SEM results, partially attributing to a wide range of its adsorption capacities on mineral surfaces. The optimum adsorption density of the caustic-digested starch on mineral surfaces, 9.87 mg/g hematite for sodium hydroxide and 10.51 mg/g hematite for potassium hydroxide, respectively, was achieved at the weight ratio of starch to sodium/potassium hydroxide as 1:2.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 1; 69-81
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Process improvement and kinetic study on copper leaching from low-grade cuprite ores
    Autorzy:
    Bai, S.
    Fu, X.
    Li, C.
    Wen, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/109660.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    cuprite
    dissolution kinetics
    sulfuric acid leaching
    SCM
    Opis:
    Process improvement and kinetic study on copper leaching from low-grade cuprite ores in sulfuric acid solution are presented in this paper. Effects of major leaching parameters on copper leaching efficiency are determined. The results indicate that copper minerals in the raw ores are mainly cuprites. The reaction rate of this ore increases with an increase in temperature, reaction time, sulfuric acid concentrations and decrease in the particle size of ore. Leaching of about 92.5% of copper is achieved using 0.125-0.074 mm ore particle size at a reaction temperature of 353 K for 180 min reaction time with 150 g/dm3 sulfuric acid. The solid/liquid ratio was maintained constant at 1:15. Leaching kinetic indicates experimental data complies with shrinking core mode (SCM). It is found in the study that agitation rate is not an influential factor on leaching rate and that the dissolution rate is controlled by surface chemical reaction. The average activation energy of the process is determined to be 45.28 kJ mol-1, and the reaction order of H2SO4 is 0.8093.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 300-310
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The surface features of activated stibnite surface with copper or lead ion
    Autorzy:
    Cao, Q.
    Huang, Y.
    Zou, H.
    Wen, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/110393.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    stibnite
    flotation
    activation
    active layer
    Opis:
    Cu2+ and Pb2+ are widely used as activators for the flotation of stibnite. In this work, by the treatment of Cu2+ or Pb2+, the activation product and the thickness of activation layer on the stibnite surface were both investigated. Based on the flotation results, zeta potential analysis and X-ray photoelectron spectroscopy (XPS) study, it was found that Cu2+ was reduced to Cu+ at the stibnite surface and a layer of Cu2S was formed at the surface. While, a PbS layer presenting at the stibnite surface is responsible for the activation flotation of stibnite with Pb2+. Time of flight secondary ion mass spectrometry (TOF-SIMS) analysis further implies that, when stibnite was activated with 5×10-5 mol/dm3 of CuSO4 or Pb(NO3)2, the thickness of Cu2S layer on the Cu-activated surface was close to 2.7 nm, while the thickness of PbS layer was about 1.8 nm on the Pb-activated surface.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 3; 763-770
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of synergistic effect between dodecylamine and sodium oleate on improving the hydrophobicity of fluorapatite
    Autorzy:
    Cao, Q.
    Luo, B.
    Wen, S.
    Cheng, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/109587.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    fluorapatite
    hydrophobicity
    synergistic effect
    mixed collector
    Opis:
    The influence of synergistic effect between dodecylamine (DDA) and sodium oleate (NaOl) on the hydrophobicity of fluorapatite (FA) was investigated with contact angle, surface tension, XPS and zeta potential studies. The role of pH and the mixing ratio of surfactants on the synergistic behavior were considered. Basing on the contact angle results the suitable pH for the NaOl-DDA mixture was pH 9.5. A further study indicated that the 3:7 DDA-NaOl mixtures could notably improve the contact angle comparing to that only with DDA or NaOl. In the solution of this mixture, the DDA cation and DDA molecule both adsorb at the FA surface as revealed by the XPS spectra results. The zeta potential analysis further suggested that the adsorption of oleate at the FA surface was also improved. The presence of DDA cation and DDA molecule was expected to result in a uniform packing of surfactants at the FA surface.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 1; 42-55
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of leaching kinetics of cerussite in sodium hydroxide solutions
    Autorzy:
    Feng, Q.
    Wen, S.
    Wang, Y.
    Zhao, W.
    Deng, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/110621.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    cerussite
    sodium hydroxide
    leaching
    kinetics
    activation energy
    Opis:
    The leaching kinetics of cerussite in alkaline medium was investigated with respect to experimental variables such as sodium hydroxide concentration, temperature, particle size and stirring speed. The results showed that leaching reagent concentration and reaction temperature exerted significant effects on the extraction of lead, whereas particle size and stirring speed exhibited a relatively moderate effect on the leaching rate. The leaching process followed the kinetic law of the shrinking core model, and the dissolution rates were controlled by the surface chemical reaction with an apparent activation energy value of 43.79 kJ/mol. A corresponding dissolution kinetic equation was also proposed to describe the dissolution reaction. The results indicated that sodium hydroxide could be used as an effective leaching reagent for extracting lead from cerussite.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 2; 491-500
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of pH on surface characteristics and flotation of sulfidized cerussite
    Autorzy:
    Feng, Q.
    Wen, S.
    Zhao, W.
    Liu, J.
    Liu, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/110234.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    cerussite
    sulfidization
    excessive sulfide ions
    pH
    surface analysis
    Opis:
    The effect of pH on surface characteristic and flotation of sulfidized cerussite was studied by micro-flotation tests, dissolution experiments, scanning electron microscopy (SEM) energy dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). The micro-flotation tests demonstrated that higher recovery of cerussite was achieved in acidic solutions than that in alkaline solutions. Despite the addition of high collector concentrations, cerussite flotation did not improved in alkaline solutions. The dissolution performance of sulfide-treated cerussite at different pH values indicated that the lead sulfide layer on the surface of sulfide-treated cerussite could exist in acidic solutions and it was more stable at acidic pH than in alkaline solutions. This finding was proved by the SEM-EDS and XPS analyses.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2016, 52, 2; 676-689
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Copper adsorption reaction rate and ion exchange ratio during the copper activation of sphalerite
    Autorzy:
    Liu, J.
    Luo, D.
    Huang, L.
    Wang, Y.
    Wen, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/110651.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    sphalerite
    copper activation
    solution chemistry
    ion exchange ratio
    reaction rate
    Opis:
    A theoretical analysis method of the solution chemistry characteristic of Cu(II) at various pH values was developed. Using such method, the existence form of Cu species and their proportions in aqueous solution can be clearly determined. After that, the copper adsorption and ion exchange ratio (E) during the copper activation of sphalerite were investigated. The results indicated that the copper activation of sphalerite can be divided into two stages, i.e., the fast activation stage (t ≤4 min) and slow activation stage (t >4 min). The general form of the copper adsorption rate was determined as ΓCu=K1ln(t) +Γ1, which is confirmed by the data fitting of the fast activation stage. The lower activation pH results in higher ion exchange efficiency for Cu substituting Zn. For a strong acid pH of 4.1, the E maintains about 1:1 in the entire activation time range and is not dependent on the activation time. However, the value of E is greater than 1 under weak acidic (pH=6.2) and alkaline (pH=9.1) pH conditions and it significantly depends on the activation time. For such conditions, E decreases with increase in the activation time, which supports the ion exchange mechanism, but within short activation time, it is not a 1:1 ion exchange process.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 377-385
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flotation behaviour and surface characteristic of anosovite in a sodium oleate solution
    Autorzy:
    Wang, Y.
    Wen, S.
    Zhang, J.
    Wu, D.
    Xian, Y.
    Shen, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/110766.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    anosovite
    sodium oleate
    flotation
    adsorption
    Opis:
    Properties of anosovite in titanium slag, anosovite flotation response in a collector solution of sodium oleate, and adsorption behaviour of sodium oleate on the mineral surface were studied in the present work using XRD, Raman spectra, flotation tests, zeta potential analysis, FTIR and XPS. The results show that the anosovite crystal contains magnesium, and its chemical composition is Mg0.09Ti2.91O5. The chemical bonds on the anosovite surface mainly comprise Ti-O bonds. Micro-flotation tests indicate that anosovite has better floatability at a wide pH range and the recovery reaches 88% at pH=6, when the dosage of sodium oleate is only 4·10−6 mol/dm3. The point of zero charge of anosovite was determined near pH 3.2 by the zeta potential measurement. In the flotation process, chemical adsorption occurs between the carboxyl of sodium oleate and the titanium sites on the anosovite surface.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 714-723
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Efficient sulfidization of lead oxide at high temperature using pyrite as vulcanizing reagent
    Autorzy:
    Zheng, Y.-X.
    Lv, J.-F.
    Wang, H.
    Wen, S.-M.
    Huang, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/110351.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    lead oxide
    sulfidization roasting
    pyrite
    reaction mechanism
    TG
    Opis:
    A sulfidization roasting-flotation process was usually viewed to be effective in treating the refractory oxide ore. In this paper, pyrite was proposed to be applied as a potential vulcanizing reagent to transform PbO or its surface to PbS based on feasibilities of technology and economy. The evolution process, phase and characteristics of crystal growth were investigated by TG, XRD and SEM-EDS, respectively, to interpret the interaction mechanism of lead oxide and pyrite at high temperature. It was found that the decomposition process of pyrite under argon atmosphere was a slow process of sulfur released from FeS2 to FexS, which made the process easier to be controlled. When PbO was introduced into the system, the initial solid-solid (PbO-FeS2) reaction and prevailing solid-gas (PbO-S2(g)) reaction occurred at about 500 °C and 700 °C, respectively. Combined with the SEM-EDS analyses results, the optimal temperature for the sulfidization of PbO should be in the range of 700-750 °C.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 270-277
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An innovative technology for recovery of zinc, lead and silver from zinc leaching residue
    Autorzy:
    Zheng, Y.-X.
    Lv, J.-F.
    Liu, W.
    Qin, W.-Q.
    Wen, S.-M.
    Powiązania:
    https://bibliotekanauki.pl/articles/110688.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    zinc leaching residue
    lead sulfate
    zinc sulfate
    reduction roasting
    flotation
    Opis:
    Zinc leaching residue is a good source of zinc and has a great potential to be utilized. However, it is very difficult to recover lead, zinc and silver from the residue by traditional technologies. In this study, a new technology based on conversions of PbSO4 and ZnSO4 in the residue to their respective sulfides by reduction roasting with coal powder followed by a flotation treatment was developed. The effects of roasting temperature, coal dosage, reaction time and pyrite dosage were investigated at a laboratory scale. The results showed that the conversion extent of PbSO4 and ZnSO4 under the optimal experimental conditions was 71.89 and 69.76%, respectively. A flotation concentrate containing 39.13% Zn, 6.93% Pb and 973.54 g/Mg Ag was obtained from the treated material, and the recovery of Zn, Pb and Ag was 48.38, 68.23 and 77.41%, respectively. The tailing containing ZnFe2O4 or Fe3O4 could be either stockpiled or further disposed.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2016, 52, 2; 943-954
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Genetic diversity and relationship of Hunan province of China local tree peonies based on SSR markers
    Autorzy:
    Zhang, M.-H.
    Jin, X.-L.
    Wen, Y.-F.
    Shen, S.
    Wen-Xing
    Wu, S.
    Lu, J.-H.
    Ye-Ye
    Powiązania:
    https://bibliotekanauki.pl/articles/12665369.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
    Tematy:
    China
    Hunan Province
    plant cultivation
    tree peony
    Paeonia suffruticosa
    ornamental plant
    genetic diversity
    genetic relationship
    SSR marker
    Opis:
    Paeonia sect. Moutan is a wide known ornamental plant in the world. The objective of this study was to provide the theoretical basis for scientific preservation and utilization of tree peony resources of Hunan province of China. Simple sequence repeat (SSR) markers were applied to reveal the genetic diversity and relationship of 21 tree peony resources and 45 domestic and foreign tree peony cultivars. Clear bands, the size of which ranged from 115 bp to 379 bp, were detected with 14 primers. In total, 90 alleles were detected and the number of alleles detected with one primer varied between 5 and 13; the number of effective alleles ranged from 1.183 to 2.070; the polymorphism ratio of each locus was 100%. The observed heterozygosity, which ranged from 0.120 to 0.851 with an average of 0.532, was larger than the expected one, which ranged from 0.090 to 0.470 with an average of 0.300. Shannon index ranged from 0.137 to 0.695 and fixation index ranged from −0.332 to −0.869. The results show abundant genetic diversity in tree peony of Hunan province and SSR markers distinguishing homonymous tree peony resources successfully.
    Źródło:
    Acta Scientiarum Polonorum. Hortorum Cultus; 2019, 18, 4; 213-223
    1644-0692
    Pojawia się w:
    Acta Scientiarum Polonorum. Hortorum Cultus
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On automatic boundedness of Nemytskiĭ set-valued operators
    Autorzy:
    Rolewicz, S.
    Song, Wen
    Powiązania:
    https://bibliotekanauki.pl/articles/1289712.pdf
    Data publikacji:
    1995
    Wydawca:
    Polska Akademia Nauk. Instytut Matematyczny PAN
    Tematy:
    Nemytskiĭ set-valued operators
    superposition measurable set-valued operators
    automatic boundedness
    modular spaces
    Opis:
    Let X, Y be two separable F-spaces. Let (Ω,Σ,μ) be a measure space with μ complete, non-atomic and σ-finite. Let $N_F$ be the Nemytskiĭ set-valued operator induced by a sup-measurable set-valued function $F:Ω × X → 2^{Y}$. It is shown that if $N_F$ maps a modular space $(N(L(Ω,Σ,μ;X)), ϱ_{N,μ})$ into subsets of a modular space $(M(L(Ω,Σ,μ;Y)),ϱ_{M,μ})$, then $N_F$ is automatically modular bounded, i.e. for each set K ⊂ N(L(Ω,Σ,μ;X)) such that $r_K = sup{ϱ_{N,μ}(x) : x ∈ K} < ∞$ we have $sup{ϱ_{M,μ}(y): y ∈ N_F(K)} < ∞$.
    Źródło:
    Studia Mathematica; 1995, 113, 1; 65-72
    0039-3223
    Pojawia się w:
    Studia Mathematica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Postures of upper extremity correlated with carpal tunnel syndrome (CTS)
    Autorzy:
    Chiang, Chia-Liang
    Liao, Chu-Yung
    Kuo, Hsien-Wen
    Powiązania:
    https://bibliotekanauki.pl/articles/2161864.pdf
    Data publikacji:
    2017-03-30
    Wydawca:
    Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
    Tematy:
    carpal tunnel syndrome
    musculoskeletal disorders
    nerve conduction velocity
    ergonomic stress
    Tinel’s signs
    Phalen test
    Opis:
    Objectives Non-medical hospital staff members are in frequent contact with patients and therefore are required to perform a wide variety of repetitive and high-frequency activities. The objective of this study was to assess the relationships between upper extremity activity and carpal tunnel syndrome (CTS) among non-medical hospital staff members. Material and Methods Carpal tunnel syndrome in 144 non-medical hospital staff members was diagnosed using the Nordic Musculoskeletal Questionnaire (NMQ), a physician’s diagnosis, physical examination (Tinel’s signs and Phalen test) and a nerve conduction velocity (NCV) test. In addition, an ergonomic assessment was performed and a video camera was used to record the physical activities at work. Results The prevalence rate of CTS was highest for the NMQ (51.9%), followed by physician’s diagnosis (49.5% for the right hand, 29.9% for the left hand), physical examination (54.7%), and nerve conduction test (motor nerve 27.5% and 25%, sensory nerve 21.7% and 15%, for right and left hands, respectively). Based on logistic regression models for the NMQ and physician’s diagnoses, there was a dose-dependently higher risk of CTS with the upper extremity index among participants, but this was non-significant based on the physical examination and nerve conduction tests. Conclusions Nerve conduction velocity is the gold standard in diagnosis of CTS, but use of NMQ and physician’s diagnosis may overestimate the incidence of CTS in workers who have been engaging in repetitive stress activities for a relatively short time. Int J Occup Med Environ Health 2017;30(2):281–290
    Źródło:
    International Journal of Occupational Medicine and Environmental Health; 2017, 30, 2; 281-290
    1232-1087
    1896-494X
    Pojawia się w:
    International Journal of Occupational Medicine and Environmental Health
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption behavior of surfactants on lignite particles with different densities in aqueous medium
    Autorzy:
    Wang, J.
    He, Y.
    Wen, B.
    Ling, X.
    Xie, W.
    Wang, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/110538.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    interfacial surface free energy
    adsorption
    lignite
    surfactant
    Washburn equation
    Opis:
    Lignite is well known for its strong hydrophilicity and hard-to-float properties. However, the surface free energy of the solid is made up of two components, that is the Lifshitz-van der Waals and acid-base interaction energy. Differences in these two components between the low ash (lower density) and high ash fraction (higher density) provide a benefit for improving the separation efficiency through introducing surfactants in flotation. In this paper, thermodynamic characterization of three density lignite fractions was measured by a Washburn dynamic method. Combining the Washburn equation and Van Oss-Chaudhury-Good theory, the surface free energy components of three samples were calculated according to the wetting process by n-hexane, diiodomethane, deionized water and ethylene glycol. The Lifshitz-van der Waals part of surface free energy reduced with the coal density increase, especially between fractions of -1.45 g/cm3 and 1.45-1.80 g/cm3, while the Lewis base part increased slightly. The interfacial interaction free energies between the surfactant and lignite in aqueous medium indicated that the low hydrophilic index benefited for the stronger adsorption intensity. Increase of the surfactant Lifshitz-van der Waals component increases the adsorptive intensity on lower density lignite and the repulsive intensity on higher density lignite, which is beneficial for separation.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 996-1008
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prediction and validation for the aerodynamic noise of high-speed train power car
    Autorzy:
    Jiang, S.
    Yang, S.
    Wu, D.
    Wen, B-Ch.
    Powiązania:
    https://bibliotekanauki.pl/articles/375504.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
    Tematy:
    aerodynamic noise
    high-speed train
    Lighthill-Curle theory
    simulation model
    online test
    hałas aerodynamiczny
    pociąg ekspresowy
    teoria Lighthilla-Curle
    model symulacyjny
    test online
    Opis:
    The aerodynamic noise of high-speed train power car was investigated in this article. The full-scale power car was first modeled, and the external steady flow field was computed by a realizable k-ε turbulence model. The aerodynamic noise sources of the power car surface and the external transient flow field were then calculated by broadband noise source model and large eddy simulation (LES) model, respectively. The static pressures on the train surface were obtained from the results of the transient model. Considering the transient flow field, the far-field aerodynamic noise generated by the power car was finally derived from Lighthill-Curle theory. It was validated by means of on-line tests that have been performed along a real high-speed railway line. Through comparisons between simulations and measurements, it is shown that the simulation model gives reliable aerodynamic noise predictions. We foresee numerous applications for modeling and control of the aerodynamic noise in high-speed train.
    Źródło:
    Transport Problems; 2018, 13, 2; 91-102
    1896-0596
    2300-861X
    Pojawia się w:
    Transport Problems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quantum Chemical Study of Aminonitrocyclopentanes as Possible High Energy Density Materials (HEDMs)
    Autorzy:
    Bai, J.
    Chi, W. J.
    Li, L. L.
    Yan, T.
    Wen, X. E.
    Li, B. T.
    Wu, H. S.
    Ma, F. L.
    Powiązania:
    https://bibliotekanauki.pl/articles/358101.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    cyclopentane derivatives
    high energy density materials
    impact sensitivity
    quantum chemistry
    DFT
    available free space
    Opis:
    Nitro and amine groups were introduced into the cyclopentane skeleton, and the heats of formation, detonation performance, bond dissociation energies, and impact sensitivity for these aminonitrocyclopentanes were calculated in detail at the B3LYP/6-311G** level. The results show that all of the derivatives have negative heats of formation, which are influenced by the position of the substituent groups. Their stabilities were estimated and analyzed according to their bond dissociation energies and calculated characteristic H50 values. Most of the compounds were found to have a lower impact sensitivity than HMX. Furthermore, the detonation velocities and detonation pressures were predicted via the Kamlet-Jacobs equation. Of all these aminonitrocyclopentanes, E has the best detonation properties (ρ = 2.05 g/cm3, D = 9.11 m/s, P = 39.62 GPa) and can be considered as a candidate high energy density material.
    Źródło:
    Central European Journal of Energetic Materials; 2013, 10, 4; 467-480
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microstructure, Mechanical and Detonation Properties of Elastomeric Micro/Ultrafine-rubber Modified TNT-based Molten Energetic Composites
    Autorzy:
    Ma, Q.
    Wang, P.-S.
    Luo, G.
    Wen, M.-P.
    Gao, D.-Y.
    Zheng, B.-H.
    Shu, Y.-J.
    Powiązania:
    https://bibliotekanauki.pl/articles/358122.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    micro and ultrafine rubber
    2,4,6-trinitrotoluene
    molten energetic composites
    mechanical properties
    detonation performance
    Opis:
    Elastomeric micro- and ultrafine-rubber are first considered as binders in melt-cast explosives for improving the mechanical properties. Acrylonitrile-butadiene rubber (NBR), in ultrafine fully vulcanized form (UF-NBR), carboxylated acrylonitrile-butadiene rubber (CNBR), in ultrafine fully vulcanized form (UF-CNBR), styrene-butadiene rubber (SBR), in ultrafine fully vulcanized form (UF-SBR), carboxylated styrene-butadiene rubber (CSBR), in ultrafine fully vulcanized form (UF-CSBR), acrylic rubber (ACM), in ultrafine fully vulcanized form (UF-ACM), room temperature vulcanized silicone rubber (RTV), in ultrafine fully vulcanized form (UF-RTV) and polytetrafluoroethene (PTFE) in micro-rubber form (PTFE-M) were utilized for modifying 2,4,6-trinitrotoluene (TNT) based melt-cast explosives. Based on their dispersity in TNT and RDX slurry, only UF-NBR, UF-CNBR and PTFE-M can be used. In the modification experiment, their influence on the mechanical and detonation performance of the matrixes were studied, as well as the impact sensitivity. Compared with PTFE-M and UF-CNBR, UF-NBR improved the tensile and compressive strength of the original formulation CYCLOTOL-65/35. The toughening mechanism was also explained through interfacial interactions and fracture energy analysis. The predicted detonation properties of the modified formulations (detonation pressure variations from 26 to 28 GPa, detonation velocity variations from 7900 to 8100 m/s) are at the same energy level as CYCLOTOL-65/35. In addition, the drop hammer impact testing results confirm that the formulation containing UF-NBR is more sensitive than the one with UF-CNBR, with the same amount of additive.
    Źródło:
    Central European Journal of Energetic Materials; 2015, 12, 4; 723-743
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new basal actinopterygian fish from the Anisian (Middle Triassic) of Luoping, Yunnan Province, Southwest China
    Autorzy:
    Wen, W.
    Zhang, Q.-Y.
    Hu, S.-X.
    Zhou, C.-Y.
    Xie, T.
    Huang, J.-Y.
    Chen, Z.Q.
    Benton, M.J.
    Powiązania:
    https://bibliotekanauki.pl/articles/21811.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    actinopterygian fish
    fish
    Anisian
    Middle Triassic
    Luoping
    Yunnan Province
    China
    Actinopterygii
    Halecomorphi
    Triassic
    Opis:
    The new neopterygian fish taxon Luoxiongichthys hyperdorsalis gen. et sp. nov. is established on the basis of five specimens from the second member of the Guanling Formation (Anisian, Middle Triassic) from Daaozi Quarry, Luoping, Yunnan Province, Southwest China. The new taxon is characterized by the following characters: triangular body outline with a distinct apex located between skull and dorsal fin; free maxilla; slender preopercular almost vertical; three suborbitals; at least eight strong branchiostegals with tubercles and comb−like ornamentation on the anterior margin; clavicles present; two postcleithra; ganoid scales covered by tubercles and pectinate ornamentation on the posterior margin with peg−and−socket structure; hemiheterocercal tail slightly forked. Comparison with basal actinopterygians reveals that the new taxon has parasemionotid−like triangular symplectics, but a semionotid opercular system. Cladistic analysis suggests that this new genus is a holostean, and either a basal halecomorph or basal semionotiform.
    Źródło:
    Acta Palaeontologica Polonica; 2012, 57, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Coelacanths from the Middle Triassic Luoping Biota, Yunnan, South China, with the earliest evidence of ovoviviparity
    Autorzy:
    Wen, W.
    Zhang, Q.-Y.
    Hu, S.-X.
    Benton, M.J.
    Zhou, C.-Y.
    Tao, X.
    Huang, J.-Y.
    Chen, Z.-Q.
    Powiązania:
    https://bibliotekanauki.pl/articles/23008.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    coelacanth
    Middle Triassic
    Triassic
    Yunnan province
    South China
    China
    evidence
    ovoviviparity
    Anisian
    Actinistia
    Coelacanthoidei
    Latimerioidei
    Opis:
    The fossil record of coelacanths is patchy, with very few taxa known from the Triassic of Asia. We report here two new genera and species of coelacanths from the Luoping Biota, a recently found site of exceptional fossil preservation from Yunnan, South China. The first new taxon, Luopingcoelacanthus eurylacrimalis, is based on four specimens, which to− gether show most aspects of the anatomy. One specimen shows two small coelacanths inside the ventral portion of the ab− dominal cavity, and these are interpreted as intrauterine embryos, close to birth size, based on comparisons with previ− ously reported embryos of the fossil coelacanths Rhabdoderma and Undina, and the extant genus Latimeria. Our new find extends the evidence for ovoviviparity in coelacanths back from the Late Jurassic to the Middle Triassic. The second new taxon, Yunnancoelacanthus acrotuberculatus, is based on one specimen, and differs from Luopingcoelacanthus in the dentary, lachrymojugal, number of rays of the first dorsal fin, and especially in the ornament on dermal bones and scales. Acladistic analysis shows that the new taxa are closest relatives to the derived clade Latimerioidei. The relatively high di− versity of coelacanths in the Early Triassic, and adaptations of living Latimeria to low−oxygen conditions, suggests that the group may have included ‘disaster taxa’ that benefited from anoxic and dysoxic ocean conditions in the aftermath of the end−Permian mass extinction.
    Źródło:
    Acta Palaeontologica Polonica; 2013, 58, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Different Ignition Responses of Powdery and Bulky 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) Based Polymer-bonded Explosives under Ultra-high Voltage Electrostatic Discharge
    Autorzy:
    Lyu, Z.
    Long, X.
    Li, Z.
    Dai, X.
    Deng, C.
    He, S.
    Li, M.
    Yao, K.
    Wen, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/358240.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    electrostatic spark sensitivity
    ultra-high voltage electrostatic discharge
    thermal effect
    electric field effect
    Opis:
    The electric spark induced ignition mechanism for explosives needs further study. The ignition of powdery and bulky TATB by electrostatic discharge (ESD) was investigated. Up to 200 kV ultra-high voltage ESD was applied to powdery and bulky explosives of two TATB-based polymer-bonded explosives (named PBX-1 and PBX-2). The results showed that the spark sensitivities of powdery and bulky explosives are extremely different for the same formulation. The 50% ignition voltages of powdery PBX-1 and PBX-2 were 10.8 kV and 8.5 kV, respectively, while the values for the bulky samples (tablets) were not less than 200 kV. Both heat and the electric field can be transmitted into the powdery samples, on the other hand only the electric field can be transmitted into the bulk samples. The electric field has a smaller contribution while the heat has a larger contribution to the ignition during an ESD, i.e., the thermal effect plays a main role in the ignition process. Our experimental results are in good agreement with recent results calculated by density functional theory.
    Źródło:
    Central European Journal of Energetic Materials; 2018, 15, 2; 283-298
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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