Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing pla...Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing plants to reduce milling cost and increase valuable mineral recovery. Based on this, the effects of nanobubbles(NBs) and hydrodynamic parameters on coarse quartz particle flotation were systematically investigated. Mechanical flotation experiments were carried out using the 7 cm and 9 cm diameter impellers in order to produce different hydrodynamic conditions. 900–1300 rpm impeller speeds were used for the 7 cm diameter impeller and 554–786 rpm for the 9 cm diameter impeller. The results show that the presence of NBs increased the flotation recovery of à425 + 106 lm quartz by up to 21%. For the7 cm diameter impeller, the maximum flotation recoveries of 86.4% and 98% were obtained in the absence and presence of NBs at Reynolds number(Re) of 81,000 and 66,000, respectively. For the 9 cm diameter impeller, the maximum recoveries of 86.3% and 97.5% were obtained in the absence and presence of NBs at Re of 90,000 and 75,000, respectively. NBs increased the flotation rate constant up to 36%.展开更多
Rare earth elements（REE） are a set of seventeen chemical elements in the periodic table, which have been found in a variety classes of minerals in the world. The global demand for REE and their compounds has increas...Rare earth elements（REE） are a set of seventeen chemical elements in the periodic table, which have been found in a variety classes of minerals in the world. The global demand for REE and their compounds has increased in high-tech applications over the past decades due to their chemical, catalytic, electrical, magnetic, and optical properties. After mining, comminution and ore beneficiation, hydrometallurgical and pyrometallurgical processes are carried out to recover REE compounds. The concentrate cracking is a process wherein the structure of a REE mineral is modified in order to dissolve REE in a weak acid solution. This would be accomplished through various techniques such as alkaline cracking and acid baking. The cracked concentrate is then leached to dissolve REE in a solution and subsequently recover those via neutralization, precipitation or solvent extraction methods. This paper reviewed the cracking and leaching methods applied to REE concentrates to produce an intermediate product for further REE separation.展开更多
In this work, compressive, flexural and split tensile strength together with coefficient of water absorption of high performance self-compacting concrete containing different amount of Fe2Os nanoparticles have been in...In this work, compressive, flexural and split tensile strength together with coefficient of water absorption of high performance self-compacting concrete containing different amount of Fe2Os nanoparticles have been investigated. The strength and the water permeability of the specimens have been improved by adding Fe2Os nanoparticles in the cement paste up to 4.0 wt%. Fe203 nanoparticle as a foreign nucleation site could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount especially at the early age of hydration and hence increase the strength of the specimens. In addition, Fe203 nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores to improve the water permeability. Several empirical relations have been presented to predict the flexural and the split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of peaks related to hydrated products in X-ray diffraction results indicate that Fe203 nanoparticles up to 4 wt% could improve the mechanical and the physical properties of the specimens.展开更多
In this work, strength assessments and percentage of water absorption of self compacting concrete containing ground granulated blast furnace slag （GGBFS） and A1203 nanoparticles as binder have been investigated. Por...In this work, strength assessments and percentage of water absorption of self compacting concrete containing ground granulated blast furnace slag （GGBFS） and A1203 nanoparticles as binder have been investigated. Portland cement was replaced by different amounts of GGBFS and the properties of concrete specimens were investigated. Although it negatively impacts the physical and mechanical properties of concrete at early ages of curing, GGBFS was found to improve the physical and mechanical properties of concrete up to 45 wt% at later ages. A1203 nanoparticles with the average particle size of 15 nm were added partially to concrete with the optimum content of GGBFS and physical and mechanical properties of the specimens were measured. A1203 nanoparticle as a partial replacement of cement up to 3.0 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early ages and hence increase strength and improve the resistance to water permeability of concrete specimens. The increase of the A1203 nanoparticles＇ content by more than 3.0 wt% would cause the reduction of the strength because of the decreased crystalline Ca（OH）2 content required for C-S-H gel formation. Several empirical relationships have been presented to predict flexural and split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of the peaks related to hydrated products in X-ray diffraction results, all indicate that A1203 nanoparticles could improve mechanical and physical properties of the concrete specimens.展开更多
In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have be...In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have been developed at different ages of curing. For purpose of building these models, training and testing using experimental results for 144 specimens produced with 16 different mixture proportions were conducted. The data used in the multilayer feed forward neural networks models and input variables of genetic programming models are arranged in a format of 8 input parameters that cover the cement content, nanoparticle content, aggregate type, water content, the amount of superplasticizer, the type of curing medium, age of curing and number of testing try. According to these input parameters, in the neural networks and genetic programming models the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles were predicted. The training and testing results in the neural network and genetic programming models have shown that every two models have strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles. It has been found that NN and GEP models will be valid within the ranges of variables. In neural networks model, as the training and testing ended when minimum error norm of network was gained, the best results were obtained and in genetic programming model, when 4 genes were selected to construct the model, the best results were acquired. Although neural network has predicted better results, genetic programming is able to predict reasonable values with a simpler method rather than neural network.展开更多
In the present study, compressive strength, pore structure, thermal behavior and microstrncture characteristics of concrete containing ground granulated blast furnace slag and TiO2 nanoparticles as binder were investi...In the present study, compressive strength, pore structure, thermal behavior and microstrncture characteristics of concrete containing ground granulated blast furnace slag and TiO2 nanoparticles as binder were investigated. Portland cement was replaced by different amounts of ground granulated blast furnace slag and the properties of concrete specimens were investigated. Al- though it negatively impacts the properties of concrete at early ages, ground granulated blast furnace slag up to 45 wt% was found to improve the physical and mechanical properties of concrete at later ages. TiO2 nanoparticles with the average particle size of 15 nm were partially added to concrete with the optimum content of ground granulated blast furnace slag and physical and mechanical properties of the specimens were measured. TiO2 nanoparticle as a partial replacement of cement up to 3 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early age of hydration and hence increase compressive strength of concrete. The increased TiO2 nanoparticles＇ content of more than 3 wt% may cause reduced compressive strength because of the decreased crystalline Ca（OH）2 content required for C-S-H gel formation and unsuitable dispersed nanoparticles in the concrete matrix. TiO2 nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and less-harm pores.展开更多
Nanotechnology is widely used in heat transfer devices to improve thermal performance.Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability.In the present...Nanotechnology is widely used in heat transfer devices to improve thermal performance.Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability.In the present article,a comprehensive literature review is performed on the nanofluids’ applications in heat pipes.Based on reviewed studies,nanofluids have a high capacity to boost the thermal behavior of various types of heat pipes such as conventional heat pipes,pulsating heat pipes,and thermosyphons.Besides,it is observed that there must be a selected amount of concentration for the high-performance utilization of nanoparticles;high concentration of nanoparticles causes a higher thermal resistance which is mainly attributed to increment in the dynamic viscosity and the higher possibility of particles’ agglomeration.Enhancement in heat transfer performance is the result of increasing in nucleation sites and the intrinsically greater nanofluids’ thermal conductivity.展开更多
Purpose： To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving. Methods： This systematic review searched the following electronic databa...Purpose： To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving. Methods： This systematic review searched the following electronic databases： Medline, Science direct, Scopus, EMBASE, PsyclNFO, Transport Database, Cochrane, BIOSIS, ISI Web of Knowledge, specialist road injuries journals and the Australian Transport and Road Index database. Additional searches included websites of relevant organizations, reference lists of included studies, and issues of major injury journals published within the past 15 years. Studies were included if they investigated interventions/exposures accounting for reducing fatigue and sleepiness as the outcome, measured any potential interventions for mitigation of sleepiness and were written in English. Meta-analysis was not attempted because of the heterogeneity of the included studies. Results： Of 63 studies identified, 18 met the inclusion criteria. Based on results of our review, many interventions in the world have been used to reduce drowsiness while driving such as behavioral （talking to passengers, face washing, listening to the radio, no alcohol use, limiting the driving behavior at the time of 12 p.m. - 6 a.m. etc）, educational interventions and also changes in the environment （such as rumble strips, chevrons, variable message signs, etc）. Meta-analysis on the effect of all these in- terventions was impossible due to the high heterogeneity in methodology, effect size and interventions reported in the assessed studies. Conclusion： Results of present review showed various interventions in different parts of the world have been used to decrease drowsy driving. Although these interventions can be used in countries with high incidence of road traffic accidents, precise effect of each intervention is still unknown. Further studies are required for comparison of the efficiency of each intervention and localization of each intervention ac- cording to the traffic pattems of each country.展开更多
Background:The side effects of the FIFA 11+program on performance have not been generally reviewed.The objective of this study was to synthesize the literature on the effects of the 11+on players’performance.Methods:...Background:The side effects of the FIFA 11+program on performance have not been generally reviewed.The objective of this study was to synthesize the literature on the effects of the 11+on players’performance.Methods:Five online databases(PubMed,Scopus,ScienceDirect,Springer,and Google Scholar)were searched(from April 2006 to March 2022)using predefined keywords and sub-keywords.The potential references were primarily recorded through Endnote and imported to Covidence.Out of the 123 references screened by 2 blinded researchers through the software,59 full texts were assessed for eligibility,33 of which were ultimately included.The quality of the studies and the risk of bias were then assessed.Study ID,title,place,aim,design,start/end dates,population description,study criteria,statistical analysis,and outcomes were extracted.Results:Studies were conducted on male and female players aged 10-32 years old.The quality of the studies was moderate to high,and except for unclear bias for blinding outcome assessment,the risk of bias for all domains was low.Long-term application of the 11+improved most biomechanical measures and physiological responses except for lower extremity stability,ankle evertors time latency,ankle dorsiflexion,and proprioception.Conversely,the 11+showed acute negative effects on physical performance compared to dynamic warm-ups and non-significant effects on technical abilities.Conclusion:Mid-to-long-term implementation of the 11+improved the maj ority of biomechanical and a couple of physical measure s but showed no effects on technical skills.Precaution must be observed for using the 11+before competitions,as it could acutely decrease physical/technical performance.Given the contradictory nature of the literature,further studies should evaluate the short-to-mid-term effects of the 11+.Further studies are required to address ankle responses to the 11+intervention.展开更多
The effects of Cu addition（0.5%, 1%, 1.5%, 2%, and 3%, mass fraction） on the quality index（Qi） and hot tearing susceptibility（HTS） of A356 alloy were investigated. According to the results, Cu addition up to 1.5...The effects of Cu addition（0.5%, 1%, 1.5%, 2%, and 3%, mass fraction） on the quality index（Qi） and hot tearing susceptibility（HTS） of A356 alloy were investigated. According to the results, Cu addition up to 1.5% increases the Qi by almost 10%, which seems to be due to its solid solution strengthening and dispersion hardening effect of Cu-rich Al2Cu and AlMgCuSi compounds. However, further addition of Cu（up to 3%） decreases the Qi by almost 12%, which is likely due to the reduction of tensile strength and elongation caused by increased volume fraction of brittle Cu-rich intermetallics and microporosities in the microstructure. It is also found that Cu increases the HTS of A356 alloy measured by constrained rod casting method. According to the thermal analysis results, Cu widens the solidification range of the alloy, which in turn, decreases its fluidity and increases the time period during which the mushy-state alloy is exposed to the hot tearing susceptible zone. SEM examination of the hot tear surfaces in high-Cu alloys also demonstrates their rough nature and the occurrence of interdendritic/intergranular microcracks as convincing evidences for the initiation of hot tears in the late stages of solidification in which there is not enough time for crack healing.展开更多
The effect of low-dosage water-soluble hydroxyethyl cellulose （approximate MW～90,000 and 250,000） as a member of hydroxyalkyl cellulosic polymer group on methane hydrate stability was investigated by monitoring hyd...The effect of low-dosage water-soluble hydroxyethyl cellulose （approximate MW～90,000 and 250,000） as a member of hydroxyalkyl cellulosic polymer group on methane hydrate stability was investigated by monitoring hydrate dissociation at pressures greater than atmospheric pressure in a closed vessel. In particular, the influence of molecular weight and mass concentration of hydroxyethyl cellulose （HEC） was studied with respect to hydrate formation and dissociation. Methane hydrate formation was performed at 2℃ and at a pressure greater than 100 bar. Afterwards, hydrate dissociation was initiated by step heating from -10℃ at a mild pressure of 13 bar to 3℃, 0℃ and 2℃. With respect to the results obtained for methane hydrate formation/dissociation and the amount of gas uptake, we concluded that HEC 90,000 at 5000 ppm is suitable for long-term gas storage and transportation under a mild pressure of 13 bar and at temperatures below the freezing point.展开更多
In the present study,abrasion resistance and compressive strength of concrete specimens containing SiO2 and CuO nanoparticles in different curing media have been investigated.Portland cement was partially replaced by ...In the present study,abrasion resistance and compressive strength of concrete specimens containing SiO2 and CuO nanoparticles in different curing media have been investigated.Portland cement was partially replaced by up to 2.0 wt%of SiO2 and CuO nanoparticles and the mechanical properties of the produced specimens were measured.Increasing the nanoparticles content was found to increase the abrasion resistance of the specimens cured in water and saturated limewater,while this condition was not observed for compressive strength in the both curing media.The enhancement of abrasion resistance was higher for the specimens containing SiO2 nanoparticles in both curing media.Since abrasion resistance and compressive strength of the specimens followed a similar regime as the nanoparticles increased for the specimens cured in saturated limewater,some experimental relationships has been presented to correlate these two properties of concrete for this curing medium.On the whole,it has been concluded that the abrasion resistance of concrete does not only depend on the corresponding compressive strength.展开更多
BACKGROUND Systemic lupus erythematosus(SLE)is a chronic autoimmune disorder impacting multiple organs,influenced by genetic factors,especially those related to the immune system.However,there is a need for new biomar...BACKGROUND Systemic lupus erythematosus(SLE)is a chronic autoimmune disorder impacting multiple organs,influenced by genetic factors,especially those related to the immune system.However,there is a need for new biomarkers in SLE.MicroRNA-125a(miR-125a)levels are decreased in T cells,B cells,and dendritic cells of SLE patients.MiR-125a plays a regulatory role in controlling the levels of tumor necrosis factor-alpha(TNF-α)and interleukin 12(IL-12),which are crucial pro-inflammatory cytokines in SLE pathogenesis.AIM To assess the levels of miR-125a,IL-12,and TNF-αin SLE patients’plasma,evaluating their diagnostic and prognostic value.METHODS The study included 100 healthy individuals,50 newly diagnosed(ND),and 50 SLE patients undergoing treatment.The patients were monitored for a duration of 24 wk to observe and record instances of relapses.MiR-125a expression was measured using real-time reverse transcription polymerase chain reaction,while ELISA kits were used to assess IL-12 and TNF-αproduction.RESULTS The results showed significantly reduced miR-125a expression in SLE patients compared to healthy individuals,with the lowest levels in ND patients.TNF-αand IL-12 expression levels were significantly elevated in SLE patients,especially in the early stages of the disease.Receiver operating characteristic curve analyses,and Cox-Mantel Log-rank tests indicated miR-125a,TNF-α,and IL-12 as proper diagnostic biomarkers for SLE.A negative correlation was found between plasma miR-125a expression and IL-12/TNF-αlevels in SLE patients.CONCLUSION Decreased miR-125a levels may be involved in the development of SLE,while elevated levels of IL-12 and TNF-αcontribute to immune dysregulation.These findings offer new diagnostic and prognostic markers for SLE.Moreover,the negative correlation observed suggests an interaction between miR-125a,TNF-α,and IL-12.Further research is necessary to uncover the underlying mechanisms that govern these relationships.展开更多
In recent decades,third-generation(3G)biofuels have become a more attractive method of fuel production,as algae cultivation does not infringe on resources needed for food production.Additionally,algae can adapt to dif...In recent decades,third-generation(3G)biofuels have become a more attractive method of fuel production,as algae cultivation does not infringe on resources needed for food production.Additionally,algae can adapt to different environments,has high photosynthetic efficiency(CO_(2)fixation),and has a high potential for carbohydrate accumulation.The prevalence of algae worldwide demonstrates its ability to adapt to different environments and climates,proving its biodiversity and versatility.Algae can be grown in wastewater,seawater,and even sewage,thus ensuring a lower water footprint and greater energy efficiency during algal biomass production.Because of this,the optimization of 3G ethanol production appears to be an excellent alternative to mitigate environmental impacts and increase energy and food security.This critical review presents(i)the stages of cultivation and processing of micro and macroalgae;(ii)the selection of yeasts(through engineering and/or bioprospecting)to produce ethanol from these biomasses;(iii)the potential of seawater-based facilities to reduce water footprint;and(iv)the mass and energy balances of 3G ethanol production in the world energy matrix.This article is,above all,a brainstorm on the environmental viability of algae bioethanol.展开更多
The prevalence of cancer,especially in industrial countries,is a major problem for health and treatment systems.Cancer can affect the quality of life of all family members and has many negative effects on the communit...The prevalence of cancer,especially in industrial countries,is a major problem for health and treatment systems.Cancer can affect the quality of life of all family members and has many negative effects on the community.Despite many advances in cancer treatment,this disease is still a major worldwide problem.There is strong evidence that dietary habits are effective in protecting against cancer and even helping in the disease treatment progress.Nuts with various biologically-active compounds,such as vitamins,phytosterols,isoflavones,flavonoids,and polyphenols have been reported to possess anticarcinogenic properties.Accordingly,this review provides an insight into the association between nut consumption and the prevention of some cancers.We considered the cancers related to the urogenital and genital tract,gastrointestinal tract,as well as women-related cancers.Both cell culture examinations and experimental animal studies alongside observational epidemiological studies demonstrated that regular consumption of a nut-enriched diet is able to reduce the risk of these cancers.展开更多
Background:As the effectiveness of breast cancer treatment has improved,a growing number of long-term breast cancer survivors are seeking help for unique health problems.These patients may be at increased risk of card...Background:As the effectiveness of breast cancer treatment has improved,a growing number of long-term breast cancer survivors are seeking help for unique health problems.These patients may be at increased risk of cardiovascular disease due to the side effects of treatment.The positive impact of most types of exercise has been repeatedly reported in people with cancer,but the most effective exercise approaches for maximum beneficial adaptations remain controversial.Thus,this study aimed to compare the effects of high-intensity interval training(HIIT)and moderate-intensity continuous training(MICT) on inflammatory indices,adipokines,metabolic markers,body composition,cardiorespiratory fitness,and quality of life in breast cancer patients during adjuvant endocrine therapy.Methods:Thirty non-metastatic breast cancer patients during adjuvant endocrine therapy who had been treated with chemotherapy and/or radiotherapy were recruited from Iran and randomized to HIIT,MICT,or control groups for a supervised exercise intervention that took place 3 times a week for 12 weeks.The training intensity was determed based on the peak oxygen uptake(VO2peak),and the volume of training was matched in HIIT and MICT based on the VO2peak.Body composition,functional capacity,cardiorespiratory fitness,metabolic indices,sex hormones,adipokines,and inflammatory markers were assessed before and after the intervention.Results:The VO2peakincreased by 16.8% in the HIIT group in comparison to baseline values(mean difference=3.61 mL/kg/min).HIIT significantly improved the VO2peakcompared to control(mean difference=3.609 mL/kg/min) and MICT(mean differences=2.974 mL/kg/min)groups.Both HIIT(mean difference=9.172 mg/dL) and MICT(mean difference=7.879 mg/dL) interventions significantly increased highdensity lipoprotein cholesterol levels compared to the control group.The analysis of covariance showed that physical well-being significantly improved in MICT compared to control group(mean difference=3.268).HIIT significantly improved the social well-bei展开更多
Instantaneous three-dimensional (3D) density distributions of a shock-cell structure of perfectly and imperfectly expanded supersonic microjets escaping into an ambient space are measured. For the 3D observation of su...Instantaneous three-dimensional (3D) density distributions of a shock-cell structure of perfectly and imperfectly expanded supersonic microjets escaping into an ambient space are measured. For the 3D observation of supersonic microjets, non-scanning 3D computerized tomography (CT) technique using a 20-directional quantitative schlieren optical system with flashlight source is employed for simultaneous schlieren photography. The 3D density distributions data of the microjets are obtained by 3D-CT reconstruction of the projection’s images using maximum likelihood-expectation maximization. Axisymmetric convergent-divergent (Laval) circular and square micro nozzles with operating nozzle pressure ratio 5.0, 4.5, 4.0, 3.67, and 3.5 have been studied. This study examines perfectly expanded, overexpanded, and underexpanded supersonic microjets issued from micro nozzles with fully expanded jet Mach numbers <em>M</em><em><sub>j</sub></em> ranging from 1.47 - 1.71, where the design Mach number is <em>M<sub>d</sub></em> = 1.5. A complex phenomenon for free square microjets called axis switching is clearly observed with two types “upright” and “diagonal” of “cross-shaped”. The initial axis-switching is 45<span style="white-space:nowrap;">°</span> within the first shock-cell range. In addition, from the symmetry and diagonal views of square microjets for the first shock-cells, two different patterns of shock waves are viewed. The shock-cell spacing and supersonic core length for all nozzle pressure ratios are investigated and reported.展开更多
Thin films of Bismuth Telluride (Bi<sub>2</sub>Te<sub>3</sub>) are prepared by thermal evaporation from nanopowders on the glass substrates. The XRD patterns of films show that all the films ar...Thin films of Bismuth Telluride (Bi<sub>2</sub>Te<sub>3</sub>) are prepared by thermal evaporation from nanopowders on the glass substrates. The XRD patterns of films show that all the films are polycrystalline and the crystalline increased by annealing temperature. Measuring of the thermoelectric power of thin films in the temperature range 300 to 380 K shows that Seebeck Coefficients have both negative and positive values, indicating that the films have both n-type and p-type conductivity. The re-crystallization of films is done by annealing from 130°C to 175°C and Seebeck Coefficient varied from -150 to 100 μV/K.展开更多
文摘Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing plants to reduce milling cost and increase valuable mineral recovery. Based on this, the effects of nanobubbles(NBs) and hydrodynamic parameters on coarse quartz particle flotation were systematically investigated. Mechanical flotation experiments were carried out using the 7 cm and 9 cm diameter impellers in order to produce different hydrodynamic conditions. 900–1300 rpm impeller speeds were used for the 7 cm diameter impeller and 554–786 rpm for the 9 cm diameter impeller. The results show that the presence of NBs increased the flotation recovery of à425 + 106 lm quartz by up to 21%. For the7 cm diameter impeller, the maximum flotation recoveries of 86.4% and 98% were obtained in the absence and presence of NBs at Reynolds number(Re) of 81,000 and 66,000, respectively. For the 9 cm diameter impeller, the maximum recoveries of 86.3% and 97.5% were obtained in the absence and presence of NBs at Re of 90,000 and 75,000, respectively. NBs increased the flotation rate constant up to 36%.
基金supported by the Research Initiation Grant of Queen’s University,Canada(#378140)Ontario Centers of Excellence VIP fund(#25394)
文摘Rare earth elements（REE） are a set of seventeen chemical elements in the periodic table, which have been found in a variety classes of minerals in the world. The global demand for REE and their compounds has increased in high-tech applications over the past decades due to their chemical, catalytic, electrical, magnetic, and optical properties. After mining, comminution and ore beneficiation, hydrometallurgical and pyrometallurgical processes are carried out to recover REE compounds. The concentrate cracking is a process wherein the structure of a REE mineral is modified in order to dissolve REE in a weak acid solution. This would be accomplished through various techniques such as alkaline cracking and acid baking. The cracked concentrate is then leached to dissolve REE in a solution and subsequently recover those via neutralization, precipitation or solvent extraction methods. This paper reviewed the cracking and leaching methods applied to REE concentrates to produce an intermediate product for further REE separation.
文摘In this work, compressive, flexural and split tensile strength together with coefficient of water absorption of high performance self-compacting concrete containing different amount of Fe2Os nanoparticles have been investigated. The strength and the water permeability of the specimens have been improved by adding Fe2Os nanoparticles in the cement paste up to 4.0 wt%. Fe203 nanoparticle as a foreign nucleation site could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount especially at the early age of hydration and hence increase the strength of the specimens. In addition, Fe203 nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores to improve the water permeability. Several empirical relations have been presented to predict the flexural and the split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of peaks related to hydrated products in X-ray diffraction results indicate that Fe203 nanoparticles up to 4 wt% could improve the mechanical and the physical properties of the specimens.
文摘In this work, strength assessments and percentage of water absorption of self compacting concrete containing ground granulated blast furnace slag （GGBFS） and A1203 nanoparticles as binder have been investigated. Portland cement was replaced by different amounts of GGBFS and the properties of concrete specimens were investigated. Although it negatively impacts the physical and mechanical properties of concrete at early ages of curing, GGBFS was found to improve the physical and mechanical properties of concrete up to 45 wt% at later ages. A1203 nanoparticles with the average particle size of 15 nm were added partially to concrete with the optimum content of GGBFS and physical and mechanical properties of the specimens were measured. A1203 nanoparticle as a partial replacement of cement up to 3.0 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early ages and hence increase strength and improve the resistance to water permeability of concrete specimens. The increase of the A1203 nanoparticles＇ content by more than 3.0 wt% would cause the reduction of the strength because of the decreased crystalline Ca（OH）2 content required for C-S-H gel formation. Several empirical relationships have been presented to predict flexural and split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of the peaks related to hydrated products in X-ray diffraction results, all indicate that A1203 nanoparticles could improve mechanical and physical properties of the concrete specimens.
文摘In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have been developed at different ages of curing. For purpose of building these models, training and testing using experimental results for 144 specimens produced with 16 different mixture proportions were conducted. The data used in the multilayer feed forward neural networks models and input variables of genetic programming models are arranged in a format of 8 input parameters that cover the cement content, nanoparticle content, aggregate type, water content, the amount of superplasticizer, the type of curing medium, age of curing and number of testing try. According to these input parameters, in the neural networks and genetic programming models the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles were predicted. The training and testing results in the neural network and genetic programming models have shown that every two models have strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles. It has been found that NN and GEP models will be valid within the ranges of variables. In neural networks model, as the training and testing ended when minimum error norm of network was gained, the best results were obtained and in genetic programming model, when 4 genes were selected to construct the model, the best results were acquired. Although neural network has predicted better results, genetic programming is able to predict reasonable values with a simpler method rather than neural network.
文摘In the present study, compressive strength, pore structure, thermal behavior and microstrncture characteristics of concrete containing ground granulated blast furnace slag and TiO2 nanoparticles as binder were investigated. Portland cement was replaced by different amounts of ground granulated blast furnace slag and the properties of concrete specimens were investigated. Al- though it negatively impacts the properties of concrete at early ages, ground granulated blast furnace slag up to 45 wt% was found to improve the physical and mechanical properties of concrete at later ages. TiO2 nanoparticles with the average particle size of 15 nm were partially added to concrete with the optimum content of ground granulated blast furnace slag and physical and mechanical properties of the specimens were measured. TiO2 nanoparticle as a partial replacement of cement up to 3 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early age of hydration and hence increase compressive strength of concrete. The increased TiO2 nanoparticles＇ content of more than 3 wt% may cause reduced compressive strength because of the decreased crystalline Ca（OH）2 content required for C-S-H gel formation and unsuitable dispersed nanoparticles in the concrete matrix. TiO2 nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and less-harm pores.
文摘Nanotechnology is widely used in heat transfer devices to improve thermal performance.Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability.In the present article,a comprehensive literature review is performed on the nanofluids’ applications in heat pipes.Based on reviewed studies,nanofluids have a high capacity to boost the thermal behavior of various types of heat pipes such as conventional heat pipes,pulsating heat pipes,and thermosyphons.Besides,it is observed that there must be a selected amount of concentration for the high-performance utilization of nanoparticles;high concentration of nanoparticles causes a higher thermal resistance which is mainly attributed to increment in the dynamic viscosity and the higher possibility of particles’ agglomeration.Enhancement in heat transfer performance is the result of increasing in nucleation sites and the intrinsically greater nanofluids’ thermal conductivity.
文摘Purpose： To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving. Methods： This systematic review searched the following electronic databases： Medline, Science direct, Scopus, EMBASE, PsyclNFO, Transport Database, Cochrane, BIOSIS, ISI Web of Knowledge, specialist road injuries journals and the Australian Transport and Road Index database. Additional searches included websites of relevant organizations, reference lists of included studies, and issues of major injury journals published within the past 15 years. Studies were included if they investigated interventions/exposures accounting for reducing fatigue and sleepiness as the outcome, measured any potential interventions for mitigation of sleepiness and were written in English. Meta-analysis was not attempted because of the heterogeneity of the included studies. Results： Of 63 studies identified, 18 met the inclusion criteria. Based on results of our review, many interventions in the world have been used to reduce drowsiness while driving such as behavioral （talking to passengers, face washing, listening to the radio, no alcohol use, limiting the driving behavior at the time of 12 p.m. - 6 a.m. etc）, educational interventions and also changes in the environment （such as rumble strips, chevrons, variable message signs, etc）. Meta-analysis on the effect of all these in- terventions was impossible due to the high heterogeneity in methodology, effect size and interventions reported in the assessed studies. Conclusion： Results of present review showed various interventions in different parts of the world have been used to decrease drowsy driving. Although these interventions can be used in countries with high incidence of road traffic accidents, precise effect of each intervention is still unknown. Further studies are required for comparison of the efficiency of each intervention and localization of each intervention ac- cording to the traffic pattems of each country.
文摘Background:The side effects of the FIFA 11+program on performance have not been generally reviewed.The objective of this study was to synthesize the literature on the effects of the 11+on players’performance.Methods:Five online databases(PubMed,Scopus,ScienceDirect,Springer,and Google Scholar)were searched(from April 2006 to March 2022)using predefined keywords and sub-keywords.The potential references were primarily recorded through Endnote and imported to Covidence.Out of the 123 references screened by 2 blinded researchers through the software,59 full texts were assessed for eligibility,33 of which were ultimately included.The quality of the studies and the risk of bias were then assessed.Study ID,title,place,aim,design,start/end dates,population description,study criteria,statistical analysis,and outcomes were extracted.Results:Studies were conducted on male and female players aged 10-32 years old.The quality of the studies was moderate to high,and except for unclear bias for blinding outcome assessment,the risk of bias for all domains was low.Long-term application of the 11+improved most biomechanical measures and physiological responses except for lower extremity stability,ankle evertors time latency,ankle dorsiflexion,and proprioception.Conversely,the 11+showed acute negative effects on physical performance compared to dynamic warm-ups and non-significant effects on technical abilities.Conclusion:Mid-to-long-term implementation of the 11+improved the maj ority of biomechanical and a couple of physical measure s but showed no effects on technical skills.Precaution must be observed for using the 11+before competitions,as it could acutely decrease physical/technical performance.Given the contradictory nature of the literature,further studies should evaluate the short-to-mid-term effects of the 11+.Further studies are required to address ankle responses to the 11+intervention.
文摘The effects of Cu addition（0.5%, 1%, 1.5%, 2%, and 3%, mass fraction） on the quality index（Qi） and hot tearing susceptibility（HTS） of A356 alloy were investigated. According to the results, Cu addition up to 1.5% increases the Qi by almost 10%, which seems to be due to its solid solution strengthening and dispersion hardening effect of Cu-rich Al2Cu and AlMgCuSi compounds. However, further addition of Cu（up to 3%） decreases the Qi by almost 12%, which is likely due to the reduction of tensile strength and elongation caused by increased volume fraction of brittle Cu-rich intermetallics and microporosities in the microstructure. It is also found that Cu increases the HTS of A356 alloy measured by constrained rod casting method. According to the thermal analysis results, Cu widens the solidification range of the alloy, which in turn, decreases its fluidity and increases the time period during which the mushy-state alloy is exposed to the hot tearing susceptible zone. SEM examination of the hot tear surfaces in high-Cu alloys also demonstrates their rough nature and the occurrence of interdendritic/intergranular microcracks as convincing evidences for the initiation of hot tears in the late stages of solidification in which there is not enough time for crack healing.
基金supported by the Research Institute of Petroleum Industry
文摘The effect of low-dosage water-soluble hydroxyethyl cellulose （approximate MW～90,000 and 250,000） as a member of hydroxyalkyl cellulosic polymer group on methane hydrate stability was investigated by monitoring hydrate dissociation at pressures greater than atmospheric pressure in a closed vessel. In particular, the influence of molecular weight and mass concentration of hydroxyethyl cellulose （HEC） was studied with respect to hydrate formation and dissociation. Methane hydrate formation was performed at 2℃ and at a pressure greater than 100 bar. Afterwards, hydrate dissociation was initiated by step heating from -10℃ at a mild pressure of 13 bar to 3℃, 0℃ and 2℃. With respect to the results obtained for methane hydrate formation/dissociation and the amount of gas uptake, we concluded that HEC 90,000 at 5000 ppm is suitable for long-term gas storage and transportation under a mild pressure of 13 bar and at temperatures below the freezing point.
文摘In the present study,abrasion resistance and compressive strength of concrete specimens containing SiO2 and CuO nanoparticles in different curing media have been investigated.Portland cement was partially replaced by up to 2.0 wt%of SiO2 and CuO nanoparticles and the mechanical properties of the produced specimens were measured.Increasing the nanoparticles content was found to increase the abrasion resistance of the specimens cured in water and saturated limewater,while this condition was not observed for compressive strength in the both curing media.The enhancement of abrasion resistance was higher for the specimens containing SiO2 nanoparticles in both curing media.Since abrasion resistance and compressive strength of the specimens followed a similar regime as the nanoparticles increased for the specimens cured in saturated limewater,some experimental relationships has been presented to correlate these two properties of concrete for this curing medium.On the whole,it has been concluded that the abrasion resistance of concrete does not only depend on the corresponding compressive strength.
基金the Department of Research and Technology at Golestan University of Medical Sciences,No.113017.
文摘BACKGROUND Systemic lupus erythematosus(SLE)is a chronic autoimmune disorder impacting multiple organs,influenced by genetic factors,especially those related to the immune system.However,there is a need for new biomarkers in SLE.MicroRNA-125a(miR-125a)levels are decreased in T cells,B cells,and dendritic cells of SLE patients.MiR-125a plays a regulatory role in controlling the levels of tumor necrosis factor-alpha(TNF-α)and interleukin 12(IL-12),which are crucial pro-inflammatory cytokines in SLE pathogenesis.AIM To assess the levels of miR-125a,IL-12,and TNF-αin SLE patients’plasma,evaluating their diagnostic and prognostic value.METHODS The study included 100 healthy individuals,50 newly diagnosed(ND),and 50 SLE patients undergoing treatment.The patients were monitored for a duration of 24 wk to observe and record instances of relapses.MiR-125a expression was measured using real-time reverse transcription polymerase chain reaction,while ELISA kits were used to assess IL-12 and TNF-αproduction.RESULTS The results showed significantly reduced miR-125a expression in SLE patients compared to healthy individuals,with the lowest levels in ND patients.TNF-αand IL-12 expression levels were significantly elevated in SLE patients,especially in the early stages of the disease.Receiver operating characteristic curve analyses,and Cox-Mantel Log-rank tests indicated miR-125a,TNF-α,and IL-12 as proper diagnostic biomarkers for SLE.A negative correlation was found between plasma miR-125a expression and IL-12/TNF-αlevels in SLE patients.CONCLUSION Decreased miR-125a levels may be involved in the development of SLE,while elevated levels of IL-12 and TNF-αcontribute to immune dysregulation.These findings offer new diagnostic and prognostic markers for SLE.Moreover,the negative correlation observed suggests an interaction between miR-125a,TNF-α,and IL-12.Further research is necessary to uncover the underlying mechanisms that govern these relationships.
基金the Coordination for the Improvement of Higher Education Personnel(CAPES)the National Council of Technological and Scientific Development(CNPq)and the Research Support Foundation of the State of Rio Grande do Sul(FAPERGS,16/2551-0000522-2,17/2551-0000893-6,19/2551-0001261-6)for the financial support+3 种基金C.Müller thanks CAPES/PNPD(88887.352933/2019-00)for a postdoctoral fellowship.M.V.Tres(308936/2017-5)G.L.Zabot(304882/2018-6)H.Treichel(305258/2018-4)L.M.Colla(305935/2017-8)thank CNPq for the productivity grants.
文摘In recent decades,third-generation(3G)biofuels have become a more attractive method of fuel production,as algae cultivation does not infringe on resources needed for food production.Additionally,algae can adapt to different environments,has high photosynthetic efficiency(CO_(2)fixation),and has a high potential for carbohydrate accumulation.The prevalence of algae worldwide demonstrates its ability to adapt to different environments and climates,proving its biodiversity and versatility.Algae can be grown in wastewater,seawater,and even sewage,thus ensuring a lower water footprint and greater energy efficiency during algal biomass production.Because of this,the optimization of 3G ethanol production appears to be an excellent alternative to mitigate environmental impacts and increase energy and food security.This critical review presents(i)the stages of cultivation and processing of micro and macroalgae;(ii)the selection of yeasts(through engineering and/or bioprospecting)to produce ethanol from these biomasses;(iii)the potential of seawater-based facilities to reduce water footprint;and(iv)the mass and energy balances of 3G ethanol production in the world energy matrix.This article is,above all,a brainstorm on the environmental viability of algae bioethanol.
文摘The prevalence of cancer,especially in industrial countries,is a major problem for health and treatment systems.Cancer can affect the quality of life of all family members and has many negative effects on the community.Despite many advances in cancer treatment,this disease is still a major worldwide problem.There is strong evidence that dietary habits are effective in protecting against cancer and even helping in the disease treatment progress.Nuts with various biologically-active compounds,such as vitamins,phytosterols,isoflavones,flavonoids,and polyphenols have been reported to possess anticarcinogenic properties.Accordingly,this review provides an insight into the association between nut consumption and the prevention of some cancers.We considered the cancers related to the urogenital and genital tract,gastrointestinal tract,as well as women-related cancers.Both cell culture examinations and experimental animal studies alongside observational epidemiological studies demonstrated that regular consumption of a nut-enriched diet is able to reduce the risk of these cancers.
基金supported by the Sport Sciences Research Institute of Iran
文摘Background:As the effectiveness of breast cancer treatment has improved,a growing number of long-term breast cancer survivors are seeking help for unique health problems.These patients may be at increased risk of cardiovascular disease due to the side effects of treatment.The positive impact of most types of exercise has been repeatedly reported in people with cancer,but the most effective exercise approaches for maximum beneficial adaptations remain controversial.Thus,this study aimed to compare the effects of high-intensity interval training(HIIT)and moderate-intensity continuous training(MICT) on inflammatory indices,adipokines,metabolic markers,body composition,cardiorespiratory fitness,and quality of life in breast cancer patients during adjuvant endocrine therapy.Methods:Thirty non-metastatic breast cancer patients during adjuvant endocrine therapy who had been treated with chemotherapy and/or radiotherapy were recruited from Iran and randomized to HIIT,MICT,or control groups for a supervised exercise intervention that took place 3 times a week for 12 weeks.The training intensity was determed based on the peak oxygen uptake(VO2peak),and the volume of training was matched in HIIT and MICT based on the VO2peak.Body composition,functional capacity,cardiorespiratory fitness,metabolic indices,sex hormones,adipokines,and inflammatory markers were assessed before and after the intervention.Results:The VO2peakincreased by 16.8% in the HIIT group in comparison to baseline values(mean difference=3.61 mL/kg/min).HIIT significantly improved the VO2peakcompared to control(mean difference=3.609 mL/kg/min) and MICT(mean differences=2.974 mL/kg/min)groups.Both HIIT(mean difference=9.172 mg/dL) and MICT(mean difference=7.879 mg/dL) interventions significantly increased highdensity lipoprotein cholesterol levels compared to the control group.The analysis of covariance showed that physical well-being significantly improved in MICT compared to control group(mean difference=3.268).HIIT significantly improved the social well-bei
文摘Instantaneous three-dimensional (3D) density distributions of a shock-cell structure of perfectly and imperfectly expanded supersonic microjets escaping into an ambient space are measured. For the 3D observation of supersonic microjets, non-scanning 3D computerized tomography (CT) technique using a 20-directional quantitative schlieren optical system with flashlight source is employed for simultaneous schlieren photography. The 3D density distributions data of the microjets are obtained by 3D-CT reconstruction of the projection’s images using maximum likelihood-expectation maximization. Axisymmetric convergent-divergent (Laval) circular and square micro nozzles with operating nozzle pressure ratio 5.0, 4.5, 4.0, 3.67, and 3.5 have been studied. This study examines perfectly expanded, overexpanded, and underexpanded supersonic microjets issued from micro nozzles with fully expanded jet Mach numbers <em>M</em><em><sub>j</sub></em> ranging from 1.47 - 1.71, where the design Mach number is <em>M<sub>d</sub></em> = 1.5. A complex phenomenon for free square microjets called axis switching is clearly observed with two types “upright” and “diagonal” of “cross-shaped”. The initial axis-switching is 45<span style="white-space:nowrap;">°</span> within the first shock-cell range. In addition, from the symmetry and diagonal views of square microjets for the first shock-cells, two different patterns of shock waves are viewed. The shock-cell spacing and supersonic core length for all nozzle pressure ratios are investigated and reported.
文摘Thin films of Bismuth Telluride (Bi<sub>2</sub>Te<sub>3</sub>) are prepared by thermal evaporation from nanopowders on the glass substrates. The XRD patterns of films show that all the films are polycrystalline and the crystalline increased by annealing temperature. Measuring of the thermoelectric power of thin films in the temperature range 300 to 380 K shows that Seebeck Coefficients have both negative and positive values, indicating that the films have both n-type and p-type conductivity. The re-crystallization of films is done by annealing from 130°C to 175°C and Seebeck Coefficient varied from -150 to 100 μV/K.
