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Wyświetlanie 1-14 z 14
Tytuł:
Second language psychological speaking and listening needs: Scale development, symbiosis, and demographic differences
Autorzy:
Xu, Jian
Qiu, Xuyan
Powiązania:
https://bibliotekanauki.pl/articles/2143622.pdf
Data publikacji:
2022-09-27
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
L2 speaking
L2 listening
psychological needs
demographic information
oracy
Opis:
This study aimed to develop and validate two parallel scales to measure the psychological L2 speaking and listening needs of 863 English-as-a-foreign language (EFL) learners. The associations between three psychological needs (i.e., autonomy, competence, and relatedness) of L2 speaking and of L2 listening were examined to develop insights into oracy (i.e., integration of speaking and listening) in L2 communication. Subsequently, the impact of demographic variables was explored. The data, collected via a 5-point Likert-scale questionnaire, were analyzed through descriptive and correlation analysis, factor analysis, and ANOVA. Exploratory factor analysis was conducted to determine the factor structures, followed by confirmatory factor analysis for validation. Results demonstrated that the validity and reliability of the two developed scales were satisfactory. L2 speaking autonomy was significantly related to L2 listening autonomy, as were competence and relatedness. The three psychological needs of both L2 speaking and listening revealed varying patterns in terms of gender, major, university geographical context, schooling stage (first year to fourth year), and study-abroad experiences. The research findings reinforce the need for integration of L2 speaking and L2 listening when satisfying university students’ psychological needs, contribute to the research field with the measurement scales of psychological needs in L2 speaking and listening settings, and yield implications for teaching the two language skills integratedly.
Źródło:
Studies in Second Language Learning and Teaching; 2022, 12, 3; 483-507
2083-5205
2084-1965
Pojawia się w:
Studies in Second Language Learning and Teaching
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineralogical factors affecting the separation behavior of Ta-Nbbearing minerals in the gravity field: mineral grain size, liberation, and association relationship
Autorzy:
Cheng, Hongwei
Xu, Jian
Wang, Shoujing
Lv, Zihu
Wei, Fushuai
Zhao, Dengkui
Wu, Dongyin
Powiązania:
https://bibliotekanauki.pl/articles/27323650.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
separation behavior
gravity field
mineralogical characteristic
columbite-tantalite
association relationship
liberation
Opis:
Gravity separation is the primary method used to beneficiate Ta-Nb-bearing minerals, however, it performs poorly in low-grade and fine-grained ores. A comparative study of gravity separation products (concentrate, middlings, and tailings) reveals the factors affecting the separation behavior of Ta-Nb-bearing minerals in the process combined with a spiral chute and shaking table from the perspective of mineralogy. The results reveal that columbite-tantalite is the principal Ta-Nb-bearing mineral. As the grinding time increases, the grade of Ta and Nb in concentrate increases significantly. The grain size of columbite-tantalite in the concentrate is the coarsest, followed by that in the middlings, and the finest in the tailings, which are mainly distributed in the range of -150+38 μm, -75+20 μm, and -38 μm, respectively. The liberation degree of columbite-tantalite in the concentrate and tailings is positively correlated with grinding time, while that in the middlings is negatively correlated with grinding time. The density of columbite-tantalite-bearing particles in concentrate is mainly distributed above 3 or even 4, due to the high liberation degree of the columbite-tantalite in the concentrate, as well as the high amount of rich intergrowth associated with heavy minerals. The density of Ta-Nb-bearing mineral particles in the middlings and tailings is predominantly distributed in D<3, owing to columbite-tantalite mainly associated with lighter gangue minerals such as quartz, albite, and orthoclase. It demonstrates that the liberation degree is not the most essential factor in determining columbite-tantalite separation behavior in the gravity field, and the mineralogical characteristics of columbite-tantalite including grain size, association relationship, and particle density, may be more important. The results of this investigation can provide theoretical support for the strengthening separation of low-grade tantalum-niobium ore.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 6; art. no. 174504
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineralogical characteristic and beneficiation evaluation of rare earth carbonate wall rock
Autorzy:
Gao, Chunqing
Yan, Guoying
Wang, Hailiang
Luo, Hongzhen
Zhang, Lin
Yang, Hanxu
Xu, Jian
Powiązania:
https://bibliotekanauki.pl/articles/2200340.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rare earth
wall rock
magnetite
fluorite
process mineralogy
beneficiation
Opis:
In order to rationalize the development and utilization of the wall rock discarded during rare earth mining, chemical analysis, inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction analysis, artificial panning, optical microscope analysis, mineral liberation analysis and energy-dispersive spectroscopy were used to study the process mineralogy of the wall rock. The results show that the main useful elements in the rare earth wall rock were iron, light rare earth elements, fluorine and niobium. Iron was mainly occurrence as magnetic iron in magnetite, rare earth elements in bastnaesite and monazite, fluorine as a independent mineral in fluorite and niobium in columbite. The main useful minerals were finely disseminated, with magnetite (48.16%), bastnaesite (49.04%), monazite (42.18%), fluorite (39.30%) and columbite (63.26%) distributed in -0.030 mm particle size. The useful minerals were evaluated separately for beneficiation based on the process mineralogical characteristics of the rare earth wall rock, and the results showed that magnetite, rare earth and fluorite resources could be effectively recovered using magnetic separation, flotation, gravity concentration and leaching enrichment methods. The sequential recovery of iron, rare earth, fluorine and niobium elements produces iron concentrate (65.40% TFe at recovery of 38.03%), rare earth concentrate (50.66% REE at recovery of 62.73%), fluorite concentrate (95.23% CaF2 at recovery of 40.34%) and niobium iron ore concentrate (1.63% Nb2O5 at recovery of 5.56%). This study provides recommendations for the rational development and utilization of rare earth wall rock and provides reasonable levels of recovery predictions.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 161300
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isolation and expression pattern of RGS21 gene, a novel RGS member
Autorzy:
Li, Xin
Chen, Lei
Ji, Chaoneng
Liu, Bing
Gu, Jiefeng
Xu, Jian
Zou, Xianqiong
Gu, Shaohua
Mao, Yumin
Powiązania:
https://bibliotekanauki.pl/articles/1041351.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
RGS21
G-protein signaling pathway
G-protein α subunit (Gα)
Opis:
Regulators of G-protein signaling (RGS) proteins are known for the RGS domain that is composed of a conserved stretch of 120 amino acids, which binds directly to activated G-protein α subunits and acts as a GTPase-activating protein (GAP), leading to their deactivation and termination of downstream signals. In this study, a novel human RGS cDNA (RGS21), 1795 bp long and encoding a 152-amino acid polypeptide, was isolated by large-scale sequencing analysis of a human fetal brain cDNA library. Unlike other RGS family members, RGS21 gene has no additional domain/motif and may represent the smallest known member of RGS family. It may belong to the B/R4 subfamily, which suggests that it may serve exclusively as a negative regulator of αi/o family members and/or αq/11. PCR analysis showed that RGS21 mRNA was expressed ubiquitously in the 16 tissues examined, implying general physiological roles.
Źródło:
Acta Biochimica Polonica; 2005, 52, 4; 943-946
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model considering residual stiffness and stiffness discontinuity of bolted joints
Autorzy:
Wang, Sheng-Ao
Zhu, Min
Xu, Zi-Jian
Guo, Ming
Li, Biao
Wu, Fei
Powiązania:
https://bibliotekanauki.pl/articles/2087050.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
nonlinear dynamic behaviour
Iwan model
energy dissipation
Opis:
The nonlinear dynamic behavior has an important impact on energy dissipation and vibra- tion damping characteristics of bolted joints. Firstly, the development of tangential dynamic models is summarized and analyzed. Secondly, a five-parameter Iwan model based on a trun- cated power-law distribution is proposed. The backbone and hysteresis curves are obtained. Thirdly, normalized and dimensionless analysis is performed. On the basis of the above, a more concise four-parameter Iwan model with stiffness continuity is proposed. Finally, the validity of the model is verified by comparing the energy dissipation vs excitation force amplitude curve with the experimental data.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 1; 63--75
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Response of methane emissions to water levels in simulated constructed wetlands
Autorzy:
Li, Yanran
Xu, Qin
Ji, Shuping
Liu, Jian
Powiązania:
https://bibliotekanauki.pl/articles/2171840.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
methane
Pearson correlation
wetland
temperature water
air temperature
metan
korelacja Pearsona
teren podmokły
temperatura wody
temperatura powietrza
Opis:
Wetland is an important natural source of methane (CH4) generated under the actions of methanogens in the anaerobic environment. A greenhouse experiment was conducted to quantify the response of methane emissions to water levels by simulating three water levels (10, 20, and 40 cm) in constructed wetlands and the methane was determined by the static chamber-gas chromatograph technique. Pearson correlation analysis showed that the emissions of CH4 were positively correlated with water temperature and air temperature while they were negatively correlated with air humidity. The water levels simulation experiment showed that the emission of CH4 was the highest when the water level was 20 cm and the CH4 concentrations of the water-air interface had different patterns at various water levels in the daytime. In conclusion, water level and temperature should be considered when accounting for greenhouse gas emissions in constructed wetlands as they both have important influences on CH4 emission.
Źródło:
Environment Protection Engineering; 2022, 48, 3; 5--12
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of particle size on flotation separation of ilmenite, olivine, and pyroxene
Autorzy:
Yang, Yaohui
Xu, Longhua
Liu, Shujun
Deng, Jian
Powiązania:
https://bibliotekanauki.pl/articles/1447002.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
olivine pyroxene
ilmenite
fine particles
narrow size
flotation separation
Opis:
The rock type in Panxi area is changing from gabbro type to olivine pyroxene type, which makes it difficult for enterprises to obtain better beneficiation indexes at present. In order to solve this problem, we use a variety of modern test techniques, such as zeta potential measurements, Fourier-transform infrared (FTIR) spectroscopy, adsorption amount measurements, and mineral-reagent interaction energy simulation to analyze the influence of particle size on mineral flotation behavior and the interaction of fine-grained minerals in this paper. The experiments results indicate that the presence of fine-grained (-19 um) mineral particles is deleterious to the flotation of ilmenite, the ilmenite recovery decreases as the microfine grade content of pyroxene and olivine increases, distribution of narrow size minerals is beneficial to the minerals flotation performance, and the order of sodium oleate (NaOL) adsorption strength on different ilmenite crystal planes is (1011) > (0001). The research results of this paper deepen the understanding of the olivine type ilmenite resources in Panxi area, enrich the theoretical system of flotation separation of refractory ilmenite, and provide theoretical support for the key technical problems of flotation separation of ilmenite in Panxi area.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 5; 106-117
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparisons Between 2D and 3D MPFEM Simulations in Modeling Uniaxial High Velocity Compaction Behaviors of Ti-6Al-4V Powder
Autorzy:
Zhou, Jian
Xu, Hongkun
Zhu, Chenyu
Wang, Bin
Liu, Kun
Powiązania:
https://bibliotekanauki.pl/articles/2048874.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multi-particle finite element method
Ti-6Al-4V
powder compaction
relative green density
impact energy per unit mass
Opis:
Multi-particle finite element method (MPFEM) simulation has been proven an efficient approach to study the densification behaviors during powder compaction. However, comprehensive comparisons between 2D and 3D MPFEM models should be made, in order to clarify which dimensional model produces more accurate prediction on the densification behaviors. In this paper, uniaxial high velocity compaction experiments using Ti-6Al-4V powder were performed under different impact energy per unit mass notated as Em. Both 2D and 3D MPFEM simulations on the powder compaction process were implemented under displacement control mode, in order to distinguish the differences. First, the experimental final green density of the compacts increased from 0.839 to 0.951 when Em was increased from 73.5 J/g to 171.5 J/g. Then detailed comparisons between two models were made with respect to the typical densification behaviors, such as the density-strain and density-pressure relations. It was revealed that densification of 2D MPFEM model could be relatively easier than 3D model for our case. Finally, validated by the experimental results, 3D MPFEM model generated more realistic predictions than 2D model, in terms of the final green density’s dependence on both the true strain and Em. The reasons were briefly explained by the discrepancies in both the particles’ degrees of freedom and the initial packing density.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 57-65
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the start-up of natural bio-film colonization of constructed rapid infiltration system
Autorzy:
Xu, W.
Yang, J.
Wang, J.
Jian, Y.
Tang, M.
Powiązania:
https://bibliotekanauki.pl/articles/259259.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
Constructed Rapid Infiltration System
start-up of natural bio-film colonization
removal rate
COD
Opis:
Abstract: this paper studied the start-up of natural bio-film colonization under the conditions where wet-to-dry ratio was 1:6, hydraulic load was 0.8m3/m2·d, and water temperature was 100C-150C, it took 25d in total to become mature, after the success of bio-film colonization, the removal rate of COD and NH4+-N can be stabilized at 80%, and the removal rate of NH4+-N can reach 90% above. The microorganism was divided into the following stages during bio-film colonization:1. Reversible adhesion of cell on the surface of the carrier, 2.Irreversible adhesion of cell on the surface of the carrier, 3.Division of cell adhering to the surface of the carrier and formation of microcolony adhering to the surface of the carrier, 4.Growth of microcolony adhering to the surface of the carrier to be mature bio-film with three-dimensional structure. The process of natural bio-film colonization can be judged comprehensively according to removal rate of NH4+-N and COD, effluent pH as well as color of microbial film.
Źródło:
Polish Maritime Research; 2016, S 1; 32-35
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Factors influencing the mental health status of support nurses and their workload during the COVID-19 epidemic
Autorzy:
Dai, Zhen-Juan
Xu, Shen-Ting
Xue, Fang-Ying
Zhou, Jian-Ying
Chen, Jian-Qin
Wang, Xue-Min
Powiązania:
https://bibliotekanauki.pl/articles/23369109.pdf
Data publikacji:
2023-12-15
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
COVID-19
mental health
epidemic prevention and control
general mental health questionnaire
NASA-TLX
support nurse
Opis:
Objectives The authors used the National Aeronautics and Space Administration Task Load Index (NASA-TLX) and general health questionnaire to analyze the factors influencing the mental health status and the workload of support nurses during the COVID-19 epidemic. Material and Methods The authors conducted a cross-sectional survey of 349 support nurses in April–October 2022. Using QuestionStar, a powerful online survey tool, the authors administered surveys to the participants, collected data on the mental health status and workload of support nurses, and analyzed the influencing factors based on the collected data. Results A total of 316 questionnaires were successfully collected, with an effective rate of 98.75%. The proportion of support nurses with mental health problems was 25% and the value of the NASA-TLX questionnaire was: M±SD 68.91±7.28 pts. Multi-factor analysis revealed that the number of children, family support, and nursing support location were the influencing factors of mental health status, while the multivariate analysis revealed that the presence of symptoms, nursing support location, support work type, and total 12-item General Health Questionnaire (GHQ-12) score were the influencing factors of the workload of support nurses. Conclusions Compared to their counterparts in the plains, nurses working in isolated plateau regions who were caring for children and lacked family support, were more likely to have mental health issues. There was a positive correlation between the changes in GHQ-12 and NASA-TLX scores of the study participants. Compared to their counterparts in the plains and the tropical regions, nurses working in plateau regions had a heavier workload. As part of the follow-up measures to prevent and treat patients impacted by the COVID-19 epidemic, it is important to improve the mental health evaluation, consultation, and treatment of the support nurses to guarantee the high quality of the first-line support work.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2023, 36, 6; 761-772
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Urinary concentrations and determinants of pyrethroid metabolites in pregnant women from non-rural areas of Yunnan, China
Autorzy:
Xu, Q.
Song, X.
Li, Y.
Jian, X.
Chen, S.
Chen, Y.
Powiązania:
https://bibliotekanauki.pl/articles/28762713.pdf
Data publikacji:
2021
Wydawca:
Instytut Medycyny Wsi
Źródło:
Annals of Agricultural and Environmental Medicine; 2021, 28, 4; 627-632
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined effects of NQO1 Pro187Ser or SULT1A1 Arg213His polymorphism and smoking on bladder cancer risk: Two meta-analyses
Autorzy:
Wang, Xiao-Chun
Wang, Jian
Tao, Hui-Hui
Zhang, Chao
Xu, Li-Fa
Powiązania:
https://bibliotekanauki.pl/articles/2161894.pdf
Data publikacji:
2017-07-14
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
polymorphisms
meta-analysis
NQO1
urinary bladder neoplasms
smoking
SULT1A1
Opis:
Objectives Objectives: Cigarette smoking is the major risk factor of bladder cancer via exposure to chemical carcinogens. Nicotinamide adenine dinucleotide phosphate (NADP+): quinine oxidoreductase 1 (NQO1) and sulfotransferase 1A1 (SULT1A1) have been reported to involve in the metabolism of polycyclic aromatic hydrocarbons (PAHs) and aromatic amines. Therefore, the risk of bladder cancer (BC) may be influenced by polymorphisms in the genes that modulate metabolic detoxification in particular by interacting with cigarette smoking. Considering the limited power by the individual studies with a relatively small sample size, especially when analyzing the combined effect of polymorphisms in NQO1 and SULT1A1 genes and smoking, these 2 meta-analyses have aimed to clarify the combined effects of them on BC risk by integrating related studies. Material and Methods Two meta-analyses included 1341 cases and 1346 controls concerning NQO1 Pro187Ser and smoking, and 1921 cases and 1882 controls on SULT1A1 Arg213His and smoking were performed. Odds ratios (OR) and 95% confidence intervals (CI) were used for assessing the strength of the association. Results The result has demonstrated that smokers with NQO1 Pro/Ser or Ser/Ser genotypes have a prominent association with the risk of BC as compared with non-smokers with NQO1 Pro/Pro genotype, with OR equal to 3.71 (95% CI: 2.87–4.78, $ \text{p}_\text{heterogeneity} $ = 0.376). Besides, smokers carrying SULT1A1 Arg/Arg genotypes were observed to confer 2.38 fold increased risk of BC (95% CI: 1.44–3.93, $ \text{p}_\text{heterogeneity} $ = 0.001) when compared with non-smokers with SULT1A1 Arg/Arg or His/His genotypes. Conclusions These findings have suggested that the NQO1 Pro187Ser or SULT1A1 Arg213His polymorphism combination with smoking significantly confer susceptibility to BC. Int J Occup Med Environ Health 2017;30(5):791–802
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2017, 30, 5; 791-802
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel tetrameric lectin from Lycoris aurea with four mannose binding sites per monomer
Autorzy:
Liu, Jiwei
Xu, Xiaochao
Liu, Jinzhi
Balzarini, Jan
Luo, Yongtin
Kong, Yang
Li, Jian
Chen, Fang
Van Damme, Els
Bao, Jinku
Powiązania:
https://bibliotekanauki.pl/articles/1041131.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
sequence alignment
mannose-binding lectin
Lycoris aurea agglutinin
molecular modeling and docking
Opis:
The mannose-binding agglutinin from bulbs of Lycoris aurea (LAA) agglutinates rabbit but not human erythrocytes. The molecular mass of the monomer in SDS/PAGE is 12 kDa while the apparent molecular mass in gel filtration is 48 kDa, indicating that LAA is a homotetramer. The full-length cDNA of LAA contains 683 bp with an open reading frame encoding a protomer of 162 amino-acid residues. Hydrophobic Cluster Analysis and molecular modeling of the 109-residue mature polypeptide suggested a similar secondary and tertiary structure to those of Narcissus pseudonarcissus agglutinin (NPA). Molecular docking revealed that, besides the three mannose-binding sites common among Amaryllidaceae lectins, LAA also contains a fourth unique mannose-binding site formed by a tryptophan cluster. The existence of four mannose-binding sites in each monomer of LAA is very unusual and has only been reported for NPA earlier.
Źródło:
Acta Biochimica Polonica; 2007, 54, 1; 159-166
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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