The effects of leaching temperature(60−105°C),NH4Cl concentration(3−7 mol/L),liquid/solid ratio(4:1−12:1 mL/g),stirring speed(150−750 r/min),and leaching time(5−90 min)on the leaching rates of Zn and Pb were inve...The effects of leaching temperature(60−105°C),NH4Cl concentration(3−7 mol/L),liquid/solid ratio(4:1−12:1 mL/g),stirring speed(150−750 r/min),and leaching time(5−90 min)on the leaching rates of Zn and Pb were investigated.The leaching kinetics of Zn-and Pb-rich fuming dust with a NH4Cl solution was also studied.The leaching rates of Zn and Pb respectively reached 98.2%and 75.6%at leaching temperature of 100°C,an NH4Cl concentration of 7.0 mol/L,a liquid/solid ratio of 10:1 mL/g,a stirring speed of 450 r/min and leaching time of 60 min.The kinetics results indicate that the leaching of Zn and Pb conforms to the shrinking unreacted core model and is controlled by the internal diffusion of NH4Cl through the reacted fuming dust layer and external diffusion of NH4Cl through the leaching solution boundary layer,respectively.The apparent activation energies of Zn and Pb are 23.922 and 19.139 kJ/mol,respectively.This study demonstrates that the use of NH4Cl solution,without ammonia,is an environmentally friendly method for simultaneous extracting Zn and Pb from the fuming dust of lead blast furnace slag.展开更多
Lead fuming furnace slag(LFFS)is a by-product of lead metal production,which is a toxic solid waste according to toxicity characteristic leaching procedure(TCLP)test.It was investigated the feasibility of preparation ...Lead fuming furnace slag(LFFS)is a by-product of lead metal production,which is a toxic solid waste according to toxicity characteristic leaching procedure(TCLP)test.It was investigated the feasibility of preparation of geopolymer using coal fly ash(CFA)and LFFS and the immobilization efficiency of Cd in geopolymer.The synthesized geopolymer samples were examined by compressive strength,Fourier transform transmission infrared spectroscopy(FTIR)spectra,X-ray diffraction(XRD)and backscattered electron(BSE)microscope.There is a certain mass ratio(2:3)of the LFFS to the CFA at which the compressive strength of the geopolymeric matrix is the highest.Leaching test shows that Cd in LFFS can be effectively immobilized in the geopolymer structure.Geopolymerization is not only a potential technological solution for reusing LFFS but also an effective immobilization method for LFFS treatment and disposal.展开更多
OBJECTIVE: To investigate clinical effect of acupuncture combined with TCM fumigation on pain and active function improvement in patients with ankylosing spondylitis. METHODS: 42 patients with ankylosing spondylitis w...OBJECTIVE: To investigate clinical effect of acupuncture combined with TCM fumigation on pain and active function improvement in patients with ankylosing spondylitis. METHODS: 42 patients with ankylosing spondylitis were selected in hospital from October 2016 to October 2017, who were randomly divided into 2 groups by number table method. 21 patients received conventional treatment as control group. 21 patients combined with acupuncture, TCM fumigation treatment as observation group. Clinical indicators, activity function, pain scores were evaluated before and after treatment. RESULTS: Erythrocyte sedimentation rate, C reactive protein, alkaline phosphatase, macrophage migration inhibitory factor, BASDAI score, BASFI score, VAS score after treatment decreased in two groups compared with before treatment(P<0.05). Chest mobility, lumbar pitch, Schober test, occipital wall distance, lumbar lateral flexion after treatment increased in two groups compared with before treatment(P<0.05). Refers to distance, morning stiffness time, rump length after treatment reduced in two groups compared with before treatment(P<0.05). Erythrocyte sedimentation rate, C reactive protein, alkaline phosphatase, macrophage migration inhibitory factor, BASDAI score, BASFI score, VAS score in observation group were lower than control group after treatment(P<0.05). Chest mobility, lumbar pitch, Schober test, occipital wall distance, lumbar lateral flexion in observation group were higher than control group after treatment(P<0.05). Refers to distance, rump length in observation group were smaller than control group after treatment(P<0.05). Morning stiffness time in observation group was less than control group after treatment(P<0.05). CONCLUSIONS: Acupuncture combined with TCM fumigation can significantly improve pain and active function in patients with ankylosing spondylitis, which is worthy of clinical promotion.展开更多
Objective: To observe the effect of oral fuming tablets on the levels of serum β2-microglobulin (β2-MG), Glycosylated hemoglobin (HbA1c), Nitric oxide (NO), Malondialdehyde (MDA) and superoxide dismutase (SOD) in pa...Objective: To observe the effect of oral fuming tablets on the levels of serum β2-microglobulin (β2-MG), Glycosylated hemoglobin (HbA1c), Nitric oxide (NO), Malondialdehyde (MDA) and superoxide dismutase (SOD) in patients with diabetic cataract (DC) after phacoemulsification combined with vitrectomy. Methods: A total of 90 patients with DC were randomly divided into control group (n=45) and observation group (n=45) according to the lottery method. Both groups were treated with conventional therapy. On this basis, the control group underwent phacoemulsification combined with vitrectomy. The observation group was treated with Fuming tablets on the basis of the control group. The levels of β2-MG, HbA1c, NO, MDA and SOD in peripheral blood were measured in all subjects. Result: Before treatment, there were no significant difference in serum levels of β2-MG, HbA1c, NO, MDA and SOD between the two groups. The levels of β2-MG, HbA1c, NO and MDA in the two groups after treatment were significantly lower than those before treatment. And the levels of β2-MG, HbA1c, NO and MDA of the observation group was notably lower than those of the control group. After treatment, the levels of SOD in the two groups were notably higher than those before treatment. And the levels of SOD of the observation group was notably higher than those of the control group after treatment. Conclusion: After phacoemulsification combined with vitrectomy, supplemented with Fuming tablet treatment can effectively reduce serum levels of β2-MG and HbA1c to improve the degree of fundus lesions in DC patients;reduce serum MDA and NO levels, increase the concentration of SOD, DC patients to restore the antioxidant energy. Fuming tablets are effective adjuvant drugs for clinical cataract surgery.展开更多
Objective: to analyze the curative effect of 0.1% sodium hyaluronate eye drops combined with Fuming capsule in the treatment of dry eye after cataract surgery. Methods: a total of 100 healthy express cataract patients...Objective: to analyze the curative effect of 0.1% sodium hyaluronate eye drops combined with Fuming capsule in the treatment of dry eye after cataract surgery. Methods: a total of 100 healthy express cataract patients with dry eye after cataract surgery were enrolled from September 2015 to November 2015, and randomly divided into two groups. Patients in the single drug group were given 0.1% sodium hyaluronate eye drops, while patients in the traditional Chinese and western medicine group were added with Fuming capsules on the basis of the single drug group. Compare the effects. Results: the symptom relief time of Chinese and western medicine group was shorter than that of single drug group, and the curative effect of dry eye was higher than that of single drug group, P<0.05. Conclusion: the application of 0.1% sodium hyaluronate eye drops and fuming capsule can effectively relieve xerophthalmia.展开更多
Introduction: Criminals’ propensity to precautionary mask their tracks such as disposing of an item of evidence in an aquatic environment (including freshwater and seawater) warrants the ongoing quest for advanced re...Introduction: Criminals’ propensity to precautionary mask their tracks such as disposing of an item of evidence in an aquatic environment (including freshwater and seawater) warrants the ongoing quest for advanced reagents and techniques that are tailored to the substrate characteristics on which the print will be developed. Aim: The study aimed to evaluate the synergic efficiency of the superglue fuming technique (using a homemade fuming chamber) and the powder technique in the development and visualization of latent fingerprints (LFPs) from different nonporous substrates submerged in an aquatic environment for up to 120 days. Materials and Methods: All selected nonporous substrates were cleaned thoroughly with a 70% alcohol swab. Natural latent prints were obtained from a single donor and the substrates were exposed to an aquatic environment. The superglue fuming (using a homemade fuming chamber) plus the powder technique was employed to develop and visualize the print. Results: Our findings disclose that the use of the superglue fuming technique together with the powder technique enhances the recovery rate of LFPs from substrates kept underwater for up to 90 days. The development of fingerprints was challenging from the substrates that were submerged in water for exactly 120 days. Conclusions: The resulting efficiency of the combined technique (superglue fuming technique using a homemade fuming chamber + powder technique) is substantially more sensitive, and selective, and performs better than the previously used stand-alone fingerprint enhancement technique. The improvised homemade fuming chamber proves to be a viable alternative to the standardized fuming cabinet in terms of functionality and sensitivity.展开更多
Cyanoacrylate fluorescent staining has become a common method for developing latent fingermarks on light-coloured or white objects.The method requires two steps and skilled operation,and the handling process has the r...Cyanoacrylate fluorescent staining has become a common method for developing latent fingermarks on light-coloured or white objects.The method requires two steps and skilled operation,and the handling process has the risk of damaging the ridge details or even biological samples.To take full advantage of the high-sensitivity fluorescence,recent research efforts on fluorescent cyanoacrylate have aimed to avoid rinsing after staining,add fluorescence to the cyanoacrylate,increase the fluorescence intensity and broaden the fluorescence spectral range.PolyCyano UV is a novel product that can be used to overcome the disadvantages associated with progressing to one-step fuming to directly develop fingermarks.To explore the optimal development conditions and application effects of PolyCyano UV,thermogravimetric differential thermal analysis,fluorescence spectroscopy and control variable analysis are used to determine and analyse the best conditions for using the reagent,including temperature,fluorescence excitation band,relative humidity and fuming concentration.The temperature range of the one-step fuming development method is 212.14℃–275.16℃,the wavelength range of the excitation light source is 235–580 nm,the relative humidity is 60%–80%,the concentration of the fume is 1–3g/m^(3) and the specific value is related to the surface properties of the object and the aged time of the fingermarks.Additionally,fluorescence spectroscopy shows that the excitation wavelength range of the light source is 235–580nm.Based on the best fuming condition,many common objects were selected to proceed to the application experiments,which allowed for a comparison with the traditional visualisation method,namely the Cyanobloom reagent+dyeing two-step development method.The comparison showed that latent fingermarks on most non-porous smooth surfaces,especially on light-coloured or white objects,were developed successfully.In addition,a comparative study with the conventional cyanoacrylate glue–fluorescent staining experiments showed that the effect of dyeing afterwards with Rhodamine 6G is better than the one-step method.The effect of dyeing with BBD is basically the same as that of the one-step method.展开更多
Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations a...Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.展开更多
Lithium-ion batteries are used extensively in civil,military,and aerospace applications because of their high energy and power density.However,in practical applications,these batteries may encounter extreme cases char...Lithium-ion batteries are used extensively in civil,military,and aerospace applications because of their high energy and power density.However,in practical applications,these batteries may encounter extreme cases characterized by transient high impacts,which impose stringent requirements on their safety and reliability.In recent years,the failure mechanism associated with the short-circuiting of lithium-ion-battery separators under high dynamic impacts has been investigated thoroughly.Based on the separator impact failure mechanism,we prepared a porous polymer polyvinylidene fluoride(PVDF)separator by doping gas-phase SiO_(2)(fumed silica)additive.The gas-phase SiO_(2)has a unique three-dimensional cluster structure,which is impact resistant.The impact resistance of the battery separator was tested using a highdynamic-impact system.The voltage drop of the battery with 3%SiO_(2)content was 33.04%of that of the original PVDF battery.Material characterization of the separator was further explored by scanning electron microscope,static compression,and pore-size adsorption tests.The SiO_(2)with a special cluster structure was distributed uniformly on the surface of the separator and embedded in the inner walls of the pores.Under static compression,the current of the SiO_(2)-PVDF separator with 3%content rose at a lower rate than that of the PVDF separator,with a minimum current of 1.04 mA.After adding SiO_(2),the separator pore size increased from 5 to 20 nm.Also,we used COMSOL to conduct impact simulations of different separators.The calculation results showed that the deformation(9.98%)and internal electrode current(0.018 A)of the SiO_(2)-PVDF lithium-ion battery were lower than the deformation(23.09%)and internal electrode current(0.049 A)of the PVDF lithium-ion battery.The SiO_(2)-doped composite polymer separator with a special cluster structure plays a crucial role in enhancing the impact resistance of lithium-ion batteries.展开更多
In this study,a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume.The equilibrium phase composition of the sulfidation reaction and calc...In this study,a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume.The equilibrium phase composition of the sulfidation reaction and calculations of the thermodynamic stability region show that 89.36%Zn,>99%Pb and>99%Cu of gypsum residue and zinc-containing fume can be sulfured to ZnS,PbS and Cu 2 S,under sufficient sulfur partial pressure,low oxygen partial pressure and 400-1000℃.Sulfidation roasting experiments show that the sulfidation rate of Cu,Pb and Zn reach 81.43%,88.25% and 92.31%,respectively,under the roasting conditions of material mass ratio of 30 g:10 g,carbon dosage of 3.75 g,roasting temperature of 800℃ for 3 h.E−pH plots show that ZnS,PbS and Cu_(2)S can be enriched in the leaching residue,under leaching conditions at 25℃,pH<4 and-0.4 V<φ(E)<0.04 V.The leaching experiments showed that the sulfide is retained in the leaching residue,while the leaching rates of Cu,Pb and Zn are 1.94%,2.05% and 1.51%,respectively,under the conditions of 25℃,C_(HCl) of 0.5 mol/L,L/S of 5 mL/g,stirring rate of 300 r/min,and stirring time of 30 min.This study provides a new approach for the synergistic disposal of gypsum residue and zinc containing fume.展开更多
Soil cement bentonite(SCB)is a common material for constructing vertical cutoff walls to prevent groundwater migration at contaminated industrial sites.However,site contaminants can degrade the durability of the cutof...Soil cement bentonite(SCB)is a common material for constructing vertical cutoff walls to prevent groundwater migration at contaminated industrial sites.However,site contaminants can degrade the durability of the cutoff wall.To enhance its performance,this study developed a silica fume-SCB(SSCB).The macroscopic and microscopic properties of SSCB were assessed by unconfined compressive strength test,variable head permeability test,X-ray diffraction(XRD),scanning electron microscopy(SEM)and nuclear magnetic resonance(NMR)spectroscopy.The correlation between its multi-scale properties was analyzed based on pore characteristics.The results indicate that increasing the silica fume substitution ratio improved SSCB strength,especially in the middle and late curing stages.Moreover,increasing the substitution ratio decreased SSCB permeability coefficient,with a more pronounced effect in earlier curing stages.Silica fume addition also refined SSCB pore structure and reduced its porosity.The fractal dimension was used to quantify SSCB pore structure complexity.Increasing silica fume content reduced small pore fractal dimension in SSCB.Concurrently,SSCB strength increased and SSCB permeability coefficient decreased.The findings of this research will demonstrate the great potential of SSCB backfill for practical applications.展开更多
Development of sustainable construction materials has been the focus of research efforts worldwide in recent years.Concrete is a major construction material;hence,finding alternatives to ordinary Portland cement is of...Development of sustainable construction materials has been the focus of research efforts worldwide in recent years.Concrete is a major construction material;hence,finding alternatives to ordinary Portland cement is of extreme importance due to the high levels of carbon dioxide emissions associated with its manufacturing process.This study investigates the geopolymerization process.Specimens with,two different water/binder weight ratios,0.30 and 0.35,were monitored using acoustic emission.Results show that there is a significant difference in the acquisition data between the two different water/binder weight ratios.In addition,acoustic emission can be used to beneficially monitor and investigate the early geopolymerization process.The acoustic emission data were processed through pattern recognition.Two clusters were identified,assigned to a specific mechanism depending on their characteristics.SEM observations were coincided with pattern recognition findings.展开更多
Objectives To characterize fine particulate matter(PM_(2.5))-bound polycyclic aromatic hydrocarbons(PAHs)emitted from different cooking fumes and their exposure routes and assess their health-associated impact to prov...Objectives To characterize fine particulate matter(PM_(2.5))-bound polycyclic aromatic hydrocarbons(PAHs)emitted from different cooking fumes and their exposure routes and assess their health-associated impact to provide a reference for health risk prevention from PAH exposure across different age and sex groups.Methods Sixteen PM_(2.5)-bound PAHs emitted from 11 cooking styles were analyzed using GC-MS/MS.The health hazards of these PAHs in the Handan City population(stratified by age and sex)were predicted using the incremental lifetime cancer risk(ILCR)model.The respiratory deposition doses(RDDs)of the PAHs in children and adults were calculated using the PM_(2.5)deposition rates in the upper airway,tracheobronchial,and alveolar regions.Results The total concentrations of PM_(2.5)-bound PAHs ranged from 61.10 to 403.80 ng/m3.Regardless of cooking styles,the ILCRtotal values for adults(1.23×10^(-6)to 3.70×10^(-6))and older adults(1.28×10^(-6)to 3.88×10^(-6))exceeded the acceptable limit of 1.00×10^(-6).With increasing age,the ILCRtotal value first declined and then increased,varying substantially among the population groups.Cancer risk exhibited particularly high sensitivity to short exposure to barbecue-derived PAHs under equivalent body weights.Furthermore,barbecue,Sichuan and Hunan cuisine,Chinese cuisine,and Chinese fast food were associated with higher RDDs for both adults and children.Conclusion ILCRtotal values exceeded the acceptable limit for both females and males of adults,with all cooking styles showing a potentially high cancer risk.Our findings serve as an important reference for refining regulatory strategies related to catering emissions and mitigating health risks associated with cooking styles.展开更多
Due to the growing need for sustainable and ultra-high-strength construction materials,scientists have created an innovative ultra-high-performance concrete called Geopolymer based ultra-highperformance concrete(GUHPC...Due to the growing need for sustainable and ultra-high-strength construction materials,scientists have created an innovative ultra-high-performance concrete called Geopolymer based ultra-highperformance concrete(GUHPC).Besides,in the last few decades,there have been a lot of explosions and ballistic attacks around the world,which have killed many civilians and fighters in border areas.In this context,this article reviews the fresh state and mechanical properties of GUHPC.Firstly,the ingredients of GUHPC and fresh properties such as setting time and flowability are briefly covered.Secondly,the review of compressive strength,flexure strength,tensile strength and modulus of elasticity of fibrous GUHPC.Thirdly,the blast and projectile impact resistance performance was reviewed.Finally,the microstructural characteristics were reviewed using the scanning electron microscope and X-ray Powder Diffraction.The review outcome reveals that the mechanical properties were increased when 30%silica fume was added to a higher dose of steel fibre to improve the microstructure of GUHPC.It is hypothesized that the brittleness of GUHPC was mitigated by adding 1.5%steel fibre reinforcement,which played a role in the decrease of contact explosion cratering and spalling.Removing the need for cement in GUHPC was a key factor in the review,indicating a promising potential for lowering carbon emissions.However,GUHPC research is still in its early stages,so more study is required before its full potential can be utilized.展开更多
ZSM-5 with hierarchical pore structure was synthesized by a simple two-step hydrothermal crystallization from silica fume without using any organic ammonium templates.The synthesized ZSM-5 were oval shaped particles w...ZSM-5 with hierarchical pore structure was synthesized by a simple two-step hydrothermal crystallization from silica fume without using any organic ammonium templates.The synthesized ZSM-5 were oval shaped particles with a particle size about 2.0 μm and weak acid-dominated with proper Brønsted(B)and Lewis(L)acid sites.The ZSM-5 was used for catalytic co-cracking of n-octane and guaiacol,lowdensity polyethylene(LDPE)and alkali lignin(AL)to enhance the production of benzene,toluene,ethylbenzene and xylene(BTEX).The most significant synergistic effect occurred at n-octane/guaiacol at 1:1 and LDPE/AL at 1:3,under the condition,the achieved BTEX selectivity were 24%and 33%(mass)higher than the calculated values(weighted average).The highest BTEX selectivity reached 88.5%,which was 3.7%and 54.2%higher than those from individual cracking LDPE and AL.The synthesized ZSM-5 exhibited superior catalytic performance compared to the commercial ZSM-5,indicating potential application prospect.展开更多
Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant...Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.展开更多
It was found that silica fume can reduce the maximum hydration heat release rate of cement by microcalorimetry,inhibit CAH_(10),promote the generation of C_(3)AH_(6)and strätlingite C_(2)ASH_(8),or promote the co...It was found that silica fume can reduce the maximum hydration heat release rate of cement by microcalorimetry,inhibit CAH_(10),promote the generation of C_(3)AH_(6)and strätlingite C_(2)ASH_(8),or promote the conversion of CAH_(10)to C_(3)AH_(6).Sodium tripolyphosphate can retard the early hydration of cement,have a slight effect on 1 d hydration products of cement and inhibit the generation hydration products.Sodium tripolyphosphate and silica fume can promote the early hydration of cement,advance the formation of C_(2)ASH_(8)or the conversion from CAH_(10)to C_(3)AH_(6)at 1 d.展开更多
This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C)in order to provide a theoretical guidance for the rational application of sili...This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C)in order to provide a theoretical guidance for the rational application of silica fume in the cementing engineering.Results showed that silica fume seldom affected the thickening progression of oil well cement slurry at 110-120.C,but when temperature reached above130.C,it would aggravate the bulging degree of thickening curves and significantly extend the thickening time,meanwhile causing the abnormal“temperature-based thickening time reversal”and“dosage-based thickening time reversal”phenomena in the range of 130-160.C and 170-180.C respectively.At 130-160.C,the thickening time of oil well cement slurry was mainly associated with the generation rate of calcium hydroxide(CH)crystal.The introduced silica fume would be attracted to the cement minerals'surface that were hydrating to produce CH and agglomerate together to form an“adsorptive barrier”to hinder further hydration of the inner cement minerals.This“adsorptive barrier”effect strengthened with the rising temperature which extended the thickening time and caused the occurrence of the“temperature-based thickening time reversal”phenomenon.At 170-180.C,the pozzolanic activity of silica fume significantly enhanced and considerable amount of C-S-H was generated,thus the“temperature-based thickening time reversal”vanished and the“dosage-based thickening time reversal”was presented.展开更多
Drying shrinkage is an important factor affecting the durability of alkali-activated materials.The drying shrinkage of alkali-activated carbon steel slag and the effect of silica fume substitution were studied.The dry...Drying shrinkage is an important factor affecting the durability of alkali-activated materials.The drying shrinkage of alkali-activated carbon steel slag and the effect of silica fume substitution were studied.The drying shrinkage test lasted for 300 d.The compressive strength,flexural strength,Vickers hardness,mass recovery and drying shrinkage recovery of the samples after drying shrinkage were tested.The hydration products and microstructure were characterized by X-ray diffraction,mercury intrusion porosimetry,thermogravimetry–differential thermogravimetry,and scanning electron microscopy–energy dispersive spectroscopy.The results show that although the chemical expansion compensates for the drying shrinkage in 42 d,the drying shrinkage increases continuously within 300 d.Silica fume affects drying shrinkage by refining pore size and increasing matrix microhardness.Solid surface tension and capillary pressure are the driving forces for drying shrinkage in the early and middle to late stages,respectively.The evolution of drying shrinkage is also influenced by chemical expansion,matrix microhardness and macropore collapse.展开更多
This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical propertie...This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical properties enhancement mechanisms were analyzed and compared through the porosity structure test, XRD analysis, and scanning electron microscope observation. The results show that the introduction of nanosilica significantly improves the dispersion of carbon nanotubes in the cement matrix. At the same time, the addition of nanosilica not only effectively reduces the critical pore size and average pore size of the cement composite material, but also exhibits good synergistic effects with carbon nanotubes, which can significantly optimize the pore structure. Finally, a rationalization suggestion for the co-doping of nanosilica and carbon nanotubes was given to achieve a significant increase in the flexural strength, compressive strength and loss factor of cement-based materials.展开更多
基金financial supports from the National Natural Science Foundation of China(No.51704107)the Department of Education Scientific Research of Hunan Province,China(No.22A0401)the Natural Science Foundation of Hunan Province,China(No.2024JJ7160).
文摘The effects of leaching temperature(60−105°C),NH4Cl concentration(3−7 mol/L),liquid/solid ratio(4:1−12:1 mL/g),stirring speed(150−750 r/min),and leaching time(5−90 min)on the leaching rates of Zn and Pb were investigated.The leaching kinetics of Zn-and Pb-rich fuming dust with a NH4Cl solution was also studied.The leaching rates of Zn and Pb respectively reached 98.2%and 75.6%at leaching temperature of 100°C,an NH4Cl concentration of 7.0 mol/L,a liquid/solid ratio of 10:1 mL/g,a stirring speed of 450 r/min and leaching time of 60 min.The kinetics results indicate that the leaching of Zn and Pb conforms to the shrinking unreacted core model and is controlled by the internal diffusion of NH4Cl through the reacted fuming dust layer and external diffusion of NH4Cl through the leaching solution boundary layer,respectively.The apparent activation energies of Zn and Pb are 23.922 and 19.139 kJ/mol,respectively.This study demonstrates that the use of NH4Cl solution,without ammonia,is an environmentally friendly method for simultaneous extracting Zn and Pb from the fuming dust of lead blast furnace slag.
基金financially supported by the National Key Project of Scientific and Technical Support Program of China(No.2012BAC02B01)the National Natural Science Foundation of China(Nos.U1360202,51472030 and 51502014)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.FRF-TP15-050A2,and FRF-TP-16-027A3)Innovation project of Yunnan Province New Material Preparation and Processing Key Laboratory(No 2016cx05)the China Postdoctoral Science Foundation Funded Project(No.2014M560885)。
文摘Lead fuming furnace slag(LFFS)is a by-product of lead metal production,which is a toxic solid waste according to toxicity characteristic leaching procedure(TCLP)test.It was investigated the feasibility of preparation of geopolymer using coal fly ash(CFA)and LFFS and the immobilization efficiency of Cd in geopolymer.The synthesized geopolymer samples were examined by compressive strength,Fourier transform transmission infrared spectroscopy(FTIR)spectra,X-ray diffraction(XRD)and backscattered electron(BSE)microscope.There is a certain mass ratio(2:3)of the LFFS to the CFA at which the compressive strength of the geopolymeric matrix is the highest.Leaching test shows that Cd in LFFS can be effectively immobilized in the geopolymer structure.Geopolymerization is not only a potential technological solution for reusing LFFS but also an effective immobilization method for LFFS treatment and disposal.
文摘OBJECTIVE: To investigate clinical effect of acupuncture combined with TCM fumigation on pain and active function improvement in patients with ankylosing spondylitis. METHODS: 42 patients with ankylosing spondylitis were selected in hospital from October 2016 to October 2017, who were randomly divided into 2 groups by number table method. 21 patients received conventional treatment as control group. 21 patients combined with acupuncture, TCM fumigation treatment as observation group. Clinical indicators, activity function, pain scores were evaluated before and after treatment. RESULTS: Erythrocyte sedimentation rate, C reactive protein, alkaline phosphatase, macrophage migration inhibitory factor, BASDAI score, BASFI score, VAS score after treatment decreased in two groups compared with before treatment(P<0.05). Chest mobility, lumbar pitch, Schober test, occipital wall distance, lumbar lateral flexion after treatment increased in two groups compared with before treatment(P<0.05). Refers to distance, morning stiffness time, rump length after treatment reduced in two groups compared with before treatment(P<0.05). Erythrocyte sedimentation rate, C reactive protein, alkaline phosphatase, macrophage migration inhibitory factor, BASDAI score, BASFI score, VAS score in observation group were lower than control group after treatment(P<0.05). Chest mobility, lumbar pitch, Schober test, occipital wall distance, lumbar lateral flexion in observation group were higher than control group after treatment(P<0.05). Refers to distance, rump length in observation group were smaller than control group after treatment(P<0.05). Morning stiffness time in observation group was less than control group after treatment(P<0.05). CONCLUSIONS: Acupuncture combined with TCM fumigation can significantly improve pain and active function in patients with ankylosing spondylitis, which is worthy of clinical promotion.
文摘Objective: To observe the effect of oral fuming tablets on the levels of serum β2-microglobulin (β2-MG), Glycosylated hemoglobin (HbA1c), Nitric oxide (NO), Malondialdehyde (MDA) and superoxide dismutase (SOD) in patients with diabetic cataract (DC) after phacoemulsification combined with vitrectomy. Methods: A total of 90 patients with DC were randomly divided into control group (n=45) and observation group (n=45) according to the lottery method. Both groups were treated with conventional therapy. On this basis, the control group underwent phacoemulsification combined with vitrectomy. The observation group was treated with Fuming tablets on the basis of the control group. The levels of β2-MG, HbA1c, NO, MDA and SOD in peripheral blood were measured in all subjects. Result: Before treatment, there were no significant difference in serum levels of β2-MG, HbA1c, NO, MDA and SOD between the two groups. The levels of β2-MG, HbA1c, NO and MDA in the two groups after treatment were significantly lower than those before treatment. And the levels of β2-MG, HbA1c, NO and MDA of the observation group was notably lower than those of the control group. After treatment, the levels of SOD in the two groups were notably higher than those before treatment. And the levels of SOD of the observation group was notably higher than those of the control group after treatment. Conclusion: After phacoemulsification combined with vitrectomy, supplemented with Fuming tablet treatment can effectively reduce serum levels of β2-MG and HbA1c to improve the degree of fundus lesions in DC patients;reduce serum MDA and NO levels, increase the concentration of SOD, DC patients to restore the antioxidant energy. Fuming tablets are effective adjuvant drugs for clinical cataract surgery.
文摘Objective: to analyze the curative effect of 0.1% sodium hyaluronate eye drops combined with Fuming capsule in the treatment of dry eye after cataract surgery. Methods: a total of 100 healthy express cataract patients with dry eye after cataract surgery were enrolled from September 2015 to November 2015, and randomly divided into two groups. Patients in the single drug group were given 0.1% sodium hyaluronate eye drops, while patients in the traditional Chinese and western medicine group were added with Fuming capsules on the basis of the single drug group. Compare the effects. Results: the symptom relief time of Chinese and western medicine group was shorter than that of single drug group, and the curative effect of dry eye was higher than that of single drug group, P<0.05. Conclusion: the application of 0.1% sodium hyaluronate eye drops and fuming capsule can effectively relieve xerophthalmia.
文摘Introduction: Criminals’ propensity to precautionary mask their tracks such as disposing of an item of evidence in an aquatic environment (including freshwater and seawater) warrants the ongoing quest for advanced reagents and techniques that are tailored to the substrate characteristics on which the print will be developed. Aim: The study aimed to evaluate the synergic efficiency of the superglue fuming technique (using a homemade fuming chamber) and the powder technique in the development and visualization of latent fingerprints (LFPs) from different nonporous substrates submerged in an aquatic environment for up to 120 days. Materials and Methods: All selected nonporous substrates were cleaned thoroughly with a 70% alcohol swab. Natural latent prints were obtained from a single donor and the substrates were exposed to an aquatic environment. The superglue fuming (using a homemade fuming chamber) plus the powder technique was employed to develop and visualize the print. Results: Our findings disclose that the use of the superglue fuming technique together with the powder technique enhances the recovery rate of LFPs from substrates kept underwater for up to 90 days. The development of fingerprints was challenging from the substrates that were submerged in water for exactly 120 days. Conclusions: The resulting efficiency of the combined technique (superglue fuming technique using a homemade fuming chamber + powder technique) is substantially more sensitive, and selective, and performs better than the previously used stand-alone fingerprint enhancement technique. The improvised homemade fuming chamber proves to be a viable alternative to the standardized fuming cabinet in terms of functionality and sensitivity.
基金supported by the Second Batch of Teaching Reform Research Project of Zhejiang Higher Education during the 13th Five-Year Plan period(No.jg20190493)Education Science Planning of Zhejiang Province in 2021 Research Project(2021SCG280).
文摘Cyanoacrylate fluorescent staining has become a common method for developing latent fingermarks on light-coloured or white objects.The method requires two steps and skilled operation,and the handling process has the risk of damaging the ridge details or even biological samples.To take full advantage of the high-sensitivity fluorescence,recent research efforts on fluorescent cyanoacrylate have aimed to avoid rinsing after staining,add fluorescence to the cyanoacrylate,increase the fluorescence intensity and broaden the fluorescence spectral range.PolyCyano UV is a novel product that can be used to overcome the disadvantages associated with progressing to one-step fuming to directly develop fingermarks.To explore the optimal development conditions and application effects of PolyCyano UV,thermogravimetric differential thermal analysis,fluorescence spectroscopy and control variable analysis are used to determine and analyse the best conditions for using the reagent,including temperature,fluorescence excitation band,relative humidity and fuming concentration.The temperature range of the one-step fuming development method is 212.14℃–275.16℃,the wavelength range of the excitation light source is 235–580 nm,the relative humidity is 60%–80%,the concentration of the fume is 1–3g/m^(3) and the specific value is related to the surface properties of the object and the aged time of the fingermarks.Additionally,fluorescence spectroscopy shows that the excitation wavelength range of the light source is 235–580nm.Based on the best fuming condition,many common objects were selected to proceed to the application experiments,which allowed for a comparison with the traditional visualisation method,namely the Cyanobloom reagent+dyeing two-step development method.The comparison showed that latent fingermarks on most non-porous smooth surfaces,especially on light-coloured or white objects,were developed successfully.In addition,a comparative study with the conventional cyanoacrylate glue–fluorescent staining experiments showed that the effect of dyeing afterwards with Rhodamine 6G is better than the one-step method.The effect of dyeing with BBD is basically the same as that of the one-step method.
文摘Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.
基金supported by the Young Elite Scientists Sponsorship Program by CAST(Grant No.2023QNRC001).
文摘Lithium-ion batteries are used extensively in civil,military,and aerospace applications because of their high energy and power density.However,in practical applications,these batteries may encounter extreme cases characterized by transient high impacts,which impose stringent requirements on their safety and reliability.In recent years,the failure mechanism associated with the short-circuiting of lithium-ion-battery separators under high dynamic impacts has been investigated thoroughly.Based on the separator impact failure mechanism,we prepared a porous polymer polyvinylidene fluoride(PVDF)separator by doping gas-phase SiO_(2)(fumed silica)additive.The gas-phase SiO_(2)has a unique three-dimensional cluster structure,which is impact resistant.The impact resistance of the battery separator was tested using a highdynamic-impact system.The voltage drop of the battery with 3%SiO_(2)content was 33.04%of that of the original PVDF battery.Material characterization of the separator was further explored by scanning electron microscope,static compression,and pore-size adsorption tests.The SiO_(2)with a special cluster structure was distributed uniformly on the surface of the separator and embedded in the inner walls of the pores.Under static compression,the current of the SiO_(2)-PVDF separator with 3%content rose at a lower rate than that of the PVDF separator,with a minimum current of 1.04 mA.After adding SiO_(2),the separator pore size increased from 5 to 20 nm.Also,we used COMSOL to conduct impact simulations of different separators.The calculation results showed that the deformation(9.98%)and internal electrode current(0.018 A)of the SiO_(2)-PVDF lithium-ion battery were lower than the deformation(23.09%)and internal electrode current(0.049 A)of the PVDF lithium-ion battery.The SiO_(2)-doped composite polymer separator with a special cluster structure plays a crucial role in enhancing the impact resistance of lithium-ion batteries.
基金Projects(52174269,52374293)supported by the National Natural Science Foundation of ChinaProject(2022RC1123)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘In this study,a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume.The equilibrium phase composition of the sulfidation reaction and calculations of the thermodynamic stability region show that 89.36%Zn,>99%Pb and>99%Cu of gypsum residue and zinc-containing fume can be sulfured to ZnS,PbS and Cu 2 S,under sufficient sulfur partial pressure,low oxygen partial pressure and 400-1000℃.Sulfidation roasting experiments show that the sulfidation rate of Cu,Pb and Zn reach 81.43%,88.25% and 92.31%,respectively,under the roasting conditions of material mass ratio of 30 g:10 g,carbon dosage of 3.75 g,roasting temperature of 800℃ for 3 h.E−pH plots show that ZnS,PbS and Cu_(2)S can be enriched in the leaching residue,under leaching conditions at 25℃,pH<4 and-0.4 V<φ(E)<0.04 V.The leaching experiments showed that the sulfide is retained in the leaching residue,while the leaching rates of Cu,Pb and Zn are 1.94%,2.05% and 1.51%,respectively,under the conditions of 25℃,C_(HCl) of 0.5 mol/L,L/S of 5 mL/g,stirring rate of 300 r/min,and stirring time of 30 min.This study provides a new approach for the synergistic disposal of gypsum residue and zinc containing fume.
基金Project(2019YFC1803601)supported by the National Key Research and Development Program of ChinaProject(52274182)supported by the National Natural Science Foundation of China+1 种基金Project(2021zzts0274)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(CX20210295)supported by the Postgraduate Scientific Research Innovation Project of Hunan Province,China。
文摘Soil cement bentonite(SCB)is a common material for constructing vertical cutoff walls to prevent groundwater migration at contaminated industrial sites.However,site contaminants can degrade the durability of the cutoff wall.To enhance its performance,this study developed a silica fume-SCB(SSCB).The macroscopic and microscopic properties of SSCB were assessed by unconfined compressive strength test,variable head permeability test,X-ray diffraction(XRD),scanning electron microscopy(SEM)and nuclear magnetic resonance(NMR)spectroscopy.The correlation between its multi-scale properties was analyzed based on pore characteristics.The results indicate that increasing the silica fume substitution ratio improved SSCB strength,especially in the middle and late curing stages.Moreover,increasing the substitution ratio decreased SSCB permeability coefficient,with a more pronounced effect in earlier curing stages.Silica fume addition also refined SSCB pore structure and reduced its porosity.The fractal dimension was used to quantify SSCB pore structure complexity.Increasing silica fume content reduced small pore fractal dimension in SSCB.Concurrently,SSCB strength increased and SSCB permeability coefficient decreased.The findings of this research will demonstrate the great potential of SSCB backfill for practical applications.
基金supported by the U.S.Department of Energy Office of Science,Office of Basic Energy Sciences,and Office of Biological and Environmental Research under Award Number DE-SC-00012530.
文摘Development of sustainable construction materials has been the focus of research efforts worldwide in recent years.Concrete is a major construction material;hence,finding alternatives to ordinary Portland cement is of extreme importance due to the high levels of carbon dioxide emissions associated with its manufacturing process.This study investigates the geopolymerization process.Specimens with,two different water/binder weight ratios,0.30 and 0.35,were monitored using acoustic emission.Results show that there is a significant difference in the acquisition data between the two different water/binder weight ratios.In addition,acoustic emission can be used to beneficially monitor and investigate the early geopolymerization process.The acoustic emission data were processed through pattern recognition.Two clusters were identified,assigned to a specific mechanism depending on their characteristics.SEM observations were coincided with pattern recognition findings.
基金supported by the National Natural Science Foundation of China(No.52330002)the Natural Science Foundation of Beijing Municipality(No.8232020)the First Batch of Key Disciplines on Public Health in Chongqing(YWBF2022072).
文摘Objectives To characterize fine particulate matter(PM_(2.5))-bound polycyclic aromatic hydrocarbons(PAHs)emitted from different cooking fumes and their exposure routes and assess their health-associated impact to provide a reference for health risk prevention from PAH exposure across different age and sex groups.Methods Sixteen PM_(2.5)-bound PAHs emitted from 11 cooking styles were analyzed using GC-MS/MS.The health hazards of these PAHs in the Handan City population(stratified by age and sex)were predicted using the incremental lifetime cancer risk(ILCR)model.The respiratory deposition doses(RDDs)of the PAHs in children and adults were calculated using the PM_(2.5)deposition rates in the upper airway,tracheobronchial,and alveolar regions.Results The total concentrations of PM_(2.5)-bound PAHs ranged from 61.10 to 403.80 ng/m3.Regardless of cooking styles,the ILCRtotal values for adults(1.23×10^(-6)to 3.70×10^(-6))and older adults(1.28×10^(-6)to 3.88×10^(-6))exceeded the acceptable limit of 1.00×10^(-6).With increasing age,the ILCRtotal value first declined and then increased,varying substantially among the population groups.Cancer risk exhibited particularly high sensitivity to short exposure to barbecue-derived PAHs under equivalent body weights.Furthermore,barbecue,Sichuan and Hunan cuisine,Chinese cuisine,and Chinese fast food were associated with higher RDDs for both adults and children.Conclusion ILCRtotal values exceeded the acceptable limit for both females and males of adults,with all cooking styles showing a potentially high cancer risk.Our findings serve as an important reference for refining regulatory strategies related to catering emissions and mitigating health risks associated with cooking styles.
文摘Due to the growing need for sustainable and ultra-high-strength construction materials,scientists have created an innovative ultra-high-performance concrete called Geopolymer based ultra-highperformance concrete(GUHPC).Besides,in the last few decades,there have been a lot of explosions and ballistic attacks around the world,which have killed many civilians and fighters in border areas.In this context,this article reviews the fresh state and mechanical properties of GUHPC.Firstly,the ingredients of GUHPC and fresh properties such as setting time and flowability are briefly covered.Secondly,the review of compressive strength,flexure strength,tensile strength and modulus of elasticity of fibrous GUHPC.Thirdly,the blast and projectile impact resistance performance was reviewed.Finally,the microstructural characteristics were reviewed using the scanning electron microscope and X-ray Powder Diffraction.The review outcome reveals that the mechanical properties were increased when 30%silica fume was added to a higher dose of steel fibre to improve the microstructure of GUHPC.It is hypothesized that the brittleness of GUHPC was mitigated by adding 1.5%steel fibre reinforcement,which played a role in the decrease of contact explosion cratering and spalling.Removing the need for cement in GUHPC was a key factor in the review,indicating a promising potential for lowering carbon emissions.However,GUHPC research is still in its early stages,so more study is required before its full potential can be utilized.
基金supported by the National Natural Science Foundation of China(22078076)Guangxi Natural Science Foundation(2020GXNSFAA159174)the Opening Project of National Enterprise Technology Center of Guangxi Bossco Environmental Protection Technology Co.,Ltd(GXU-BFY-2020-005).
文摘ZSM-5 with hierarchical pore structure was synthesized by a simple two-step hydrothermal crystallization from silica fume without using any organic ammonium templates.The synthesized ZSM-5 were oval shaped particles with a particle size about 2.0 μm and weak acid-dominated with proper Brønsted(B)and Lewis(L)acid sites.The ZSM-5 was used for catalytic co-cracking of n-octane and guaiacol,lowdensity polyethylene(LDPE)and alkali lignin(AL)to enhance the production of benzene,toluene,ethylbenzene and xylene(BTEX).The most significant synergistic effect occurred at n-octane/guaiacol at 1:1 and LDPE/AL at 1:3,under the condition,the achieved BTEX selectivity were 24%and 33%(mass)higher than the calculated values(weighted average).The highest BTEX selectivity reached 88.5%,which was 3.7%and 54.2%higher than those from individual cracking LDPE and AL.The synthesized ZSM-5 exhibited superior catalytic performance compared to the commercial ZSM-5,indicating potential application prospect.
基金SASTRA Deemed University,India for its generous research support。
文摘Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.
基金Funded by the National Natural Science Foundation of China(No.51802235)Hubei Science and Technology Innovation Talent Project,China(No.2023DJC087)。
文摘It was found that silica fume can reduce the maximum hydration heat release rate of cement by microcalorimetry,inhibit CAH_(10),promote the generation of C_(3)AH_(6)and strätlingite C_(2)ASH_(8),or promote the conversion of CAH_(10)to C_(3)AH_(6).Sodium tripolyphosphate can retard the early hydration of cement,have a slight effect on 1 d hydration products of cement and inhibit the generation hydration products.Sodium tripolyphosphate and silica fume can promote the early hydration of cement,advance the formation of C_(2)ASH_(8)or the conversion from CAH_(10)to C_(3)AH_(6)at 1 d.
基金supported by the Basic Research and Strategic Reserve Technology Research Fund Project of China National Petroleum Corporation (Grant No.2021DQ03-14)the National Natu ral Science Foundation of China (Grant No.52204010)Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C)in order to provide a theoretical guidance for the rational application of silica fume in the cementing engineering.Results showed that silica fume seldom affected the thickening progression of oil well cement slurry at 110-120.C,but when temperature reached above130.C,it would aggravate the bulging degree of thickening curves and significantly extend the thickening time,meanwhile causing the abnormal“temperature-based thickening time reversal”and“dosage-based thickening time reversal”phenomena in the range of 130-160.C and 170-180.C respectively.At 130-160.C,the thickening time of oil well cement slurry was mainly associated with the generation rate of calcium hydroxide(CH)crystal.The introduced silica fume would be attracted to the cement minerals'surface that were hydrating to produce CH and agglomerate together to form an“adsorptive barrier”to hinder further hydration of the inner cement minerals.This“adsorptive barrier”effect strengthened with the rising temperature which extended the thickening time and caused the occurrence of the“temperature-based thickening time reversal”phenomenon.At 170-180.C,the pozzolanic activity of silica fume significantly enhanced and considerable amount of C-S-H was generated,thus the“temperature-based thickening time reversal”vanished and the“dosage-based thickening time reversal”was presented.
基金This work is supported by the Fundamental Research Program of Shanxi Province in China(202403021211083)the Central Government Guided Local Science and Technology Development Project of China(No.YDZJSX20231A007)the Natural Science Young Foundation of Shanxi Province in China(201901D211178)to which the authors are very grateful.
文摘Drying shrinkage is an important factor affecting the durability of alkali-activated materials.The drying shrinkage of alkali-activated carbon steel slag and the effect of silica fume substitution were studied.The drying shrinkage test lasted for 300 d.The compressive strength,flexural strength,Vickers hardness,mass recovery and drying shrinkage recovery of the samples after drying shrinkage were tested.The hydration products and microstructure were characterized by X-ray diffraction,mercury intrusion porosimetry,thermogravimetry–differential thermogravimetry,and scanning electron microscopy–energy dispersive spectroscopy.The results show that although the chemical expansion compensates for the drying shrinkage in 42 d,the drying shrinkage increases continuously within 300 d.Silica fume affects drying shrinkage by refining pore size and increasing matrix microhardness.Solid surface tension and capillary pressure are the driving forces for drying shrinkage in the early and middle to late stages,respectively.The evolution of drying shrinkage is also influenced by chemical expansion,matrix microhardness and macropore collapse.
文摘This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical properties enhancement mechanisms were analyzed and compared through the porosity structure test, XRD analysis, and scanning electron microscope observation. The results show that the introduction of nanosilica significantly improves the dispersion of carbon nanotubes in the cement matrix. At the same time, the addition of nanosilica not only effectively reduces the critical pore size and average pore size of the cement composite material, but also exhibits good synergistic effects with carbon nanotubes, which can significantly optimize the pore structure. Finally, a rationalization suggestion for the co-doping of nanosilica and carbon nanotubes was given to achieve a significant increase in the flexural strength, compressive strength and loss factor of cement-based materials.
