According the importance of the stored grains and other products,it is an essential to keep them from khapra beetle,Trogoderma granarium infestation.This study determined the mortality percentage of 5th instar larvae ...According the importance of the stored grains and other products,it is an essential to keep them from khapra beetle,Trogoderma granarium infestation.This study determined the mortality percentage of 5th instar larvae of T.granarium fed on wheat seeds(25 gm)treated with different weights of silica as well as silica nanoparticles(20,40,60 and 80 mg)at different temperature(9℃,25℃,and 35℃).Study showed that using silica nanoparticles in cold temperature(9℃)was the most efficient treatment with the lowest LC_(50)(lethal concentration required to kill 50%of the population)value and caused the highest toxicity index.In contrast,the least efficient treatment(25℃)with the highest LC_(50) value and showed lowest toxicity index was using silica in normal temperature,when using silica nanoparticles,the cold temperature was the best condition followed by hot temperature(35℃)and finally the normal temperature.On the other hand,using silica in hot temperature was most effective followed by silica with cold temperature and finally silica with normal temperature.The biochemical assays revealed that the change in the experimental temperature had a nonsignificant effect on the total protein content of the larvae.The total lipids and total carbohydrates exhibited a significant increase due to hot treating.5th instar larvae of T.granarium treated with LC50 of silica at high temperature led to a nonsignificant(p≤0.05)decrease in Acetylcholinesterase(AchE)activity compared to treatment at normal temperature.In contrast,Glutathione S-transferase(GST)and Peroxidase activities were significantly(p≤0.05)raised due to the treatment conducted at high temperature.Additionally,treating larvae with LC50 of silica nanoparticles at low temperature caused a significant increase in both GST and peroxidase activities,while the increase in AChE was nonsignificantly(p≤0.05)compared to treatment at normal temperature.Using silica at low temperature could be used as an alternative to chemical insecticides to control T.granarium larvae.展开更多
Smart low-solid drilling fluids(SLSDFs)with thermo-controllable rheological properties and attractive thickening characteristics have recently captivated profound attention due to their low formation damage and enhanc...Smart low-solid drilling fluids(SLSDFs)with thermo-controllable rheological properties and attractive thickening characteristics have recently captivated profound attention due to their low formation damage and enhanced cuttings lifting capacity.However,their applications to deep hole drilling at high temperatures have remained limited because of the thermal instability and environmental constraints of the thermo-associating polymers as additives.This work explored the synergistic benefits of thermo-associating polymer and biogenic nano-silica(B-SiNP)extracted from rice husk to improve the thermo-stability of SLSDF.This study shows that the nano-hybrid,TAP-S based on vinyl-terminated B-SiNP could potentially mitigate the limiting performance of conventional LSDF(F-2)caused by the failure of thermo-associating copolymers under elevated temperatures.TAP-S bearing drilling fluid(F-3)could preserve more than 5.6-fold of its initial properties(ca.apparent viscosity,plastic viscosity,yield point,and gel strength)with a nearly flat-gel profile in the temperature range of 25-230℃,which was higher than those of the counterpart F-2 and base fluid according to the results of rheological tests analysis.In addition,TAP-S exhibited an abrupt thermo-thickening characteristic with a magnitude declining by only 1.05-fold and the activation Gibbs free energy of 1339 kJ/mol above the plateau(ca.130℃),reflecting its less sensitivity compared to F-2 under a continuous heating process.As a result,a lower temperature was required to drive the dehydration of the residual fraction of lower critical solution temperature(LCST)in nano-hybrid structures than TAP according to the results of DSC analysis.Thus,lower energy was expected to disintegrate the residual hydrogen bonds formed between the LCST chains and surrounding water molecules at elevated temperatures.Moreover,TAP-S formed a solid-micro-crosslinking structure network which exhibited a more stable hydrodynamic diameter as revealed by DLS analysis.Compared with TAP,TAP-S consisted of a larger composite B-SiNP-TAP integrated spatial network structure based on the results of environmental scanning electron microscope,which conferred a degree of thermal conductivity characteristic for improved temperature resistance.This contributed to the effective binding onto bentonite particles for protection and maintained a relatively stable bentonite particle dispersion according to the results of EPM and particle size distribution analyses.Consequently,TAP-S fortified drilling fluid demonstrates improved rheological and filtration performance under severe downhole conditions.Therefore,TAP-S,the thermo-associating copolymer integrated with B-SiNP could find potential application as an eco-friendly viscosifier in LSDFs for deep-well drilling operations.展开更多
Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not bee...Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.展开更多
An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy soil.Cement agent included Portland cement type II.Cement content was 6%...An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy soil.Cement agent included Portland cement type II.Cement content was 6% by weight of the sandy soil.Nanosilica was added in percentages of 0%,4%,8% and 12% by weight of cement.Cylindrical samples were prepared with relative density of 80% and optimum water content and cured for 7 d,28 d and 90 d.Microstructure characteristics of cementnanosilica-sand mixtures after 90 d of curing have been explored using atomic force microscopy(AFM),scanning electron microscopy(SEM) and X-ray diffraction(XRD) tests.Effects of curing time on microstructure properties of cemented sandy soil samples with 0% and 8% nanosilica have been investigated using SEM test.Unconfined compression test(for all curing times) and compaction test were also performed.The SEM and AFM tests results showed that nanosilica contributes to enhancement of cemented sandy soil through yielding denser,more uniform structure.The XRD test demonstrated that the inclusion of nanosilica in the cemented soil increases the intensity of the calcium silicate hydrate(CSH) peak and decreases the intensity of the calcium hydroxide(CH) peak.The results showed that adding optimum percentages of nanosilica to cement-stabilized sandy soil enhances its mechanical and microstructure properties.展开更多
A novel synthesis of hierarchical porous carbons （HPCs）with 3D open-cell structure based on nanosilica- embedded emulsion-templated polymerization was reported. An oil-in-water emulsion containing SiO2 colloids was ...A novel synthesis of hierarchical porous carbons （HPCs）with 3D open-cell structure based on nanosilica- embedded emulsion-templated polymerization was reported. An oil-in-water emulsion containing SiO2 colloids was fabricated using liquid paraffin as an oil phase, resorcinol/formaldehyde and silica sol as an aqueous phase, and Span 80/Tween 80 as emulsifiers. HPCs with macropore cores, open meso/ macropore windows, and abundant micropores were synthesized by the polymerization and carbonization of the emulsion, followed by scaffold removal and further KOH activation. A typical HPCs sample as supercapacitor electrode shows the charge/discharge capability under large loading current density （30 A/g） coupling with a reasonable electrochemical capacitance in KOH electrolyte solution.展开更多
This paper describes the electrodeposition of polyphosphate-doped polypyrrole/nanosilica nano-composite coating on steel wire for direct solid-phase microextraction of bisphenol A and five phthalates. We optimized inf...This paper describes the electrodeposition of polyphosphate-doped polypyrrole/nanosilica nano-composite coating on steel wire for direct solid-phase microextraction of bisphenol A and five phthalates. We optimized influencing parameters on the extraction efficiency and morphology of the nanocomposite such as deposition potential, concentration of pyrrole and polyphosphate, deposition time and the nanosilica amount. Under the optimized conditions, characterization of the nanocomposite was inves-tigated by scanning electron microscopy and Fourier transform infra-red spectroscopy. Also, the factors related to the solid-phase microextraction method including desorption temperature and time, extrac-tion temperature and time, ionic strength and pH were studied in detail. Subsequently, the proposed method was validated by gas chromatography-mass spectrometry by thermal desorption and acceptable figures of merit were obtained. The linearity of the calibration curves was between 0.01 and 50 ng/mL with acceptable correlation coefficients (0.9956-0.9987) and limits of detection were in the range 0.002-0.01 ng/mL. Relative standard deviations in terms of intra-day and inter-day by five replicate analyses from aqueous solutions containing 0.1 ng/mL of target analytes were in the range 3.3%-5.4% and 5%-7.1%, respectively. Fiber-to-fiber reproducibilities were measured for three different fibers prepared in the same conditions and the results were between 7.3% and 9.8%. Also, extraction recoveries at two different concentrations were ≥96%. Finally, the suitability of the proposed method was demonstrated through its application to the analysis of some eye drops and injection solutions.展开更多
Implantable electronic devices(IEDs)are widely used by human beings to achieve medical treatment and diagnosis nowadays.However,ideal encapsulation of IEDs is still far from perfect as full prevention of body fluid di...Implantable electronic devices(IEDs)are widely used by human beings to achieve medical treatment and diagnosis nowadays.However,ideal encapsulation of IEDs is still far from perfect as full prevention of body fluid diffusion into the coating remains unsolved.Herein,we develop a high-performance composite coating for IED encapsulation by introducing SiO_(2) nanoparticles into silicone rubber,which synergistically enhances mechanical properties and improves barrier performance.By fabricating composite coatings with different nanosilica contents,3%nanosilica is proved to be an optimal additive content with an excellent combination of improved fracture strength(from 2.5 MPa to 4.5 MPa),increased coating resistance(from 10^(4) to 10^(9) cm^(2))and ideal coating uniformity.Mechanical and electrochemical characterizations subsequently confirm substantially enhanced mechanical properties and barrier performance of the composite coating,which effectively resist crack propagation and impede penetrations of water and chloride ions through the coating.Theoretical calculations further uncover that modified SiO_(2) particles with enriched methyl groups endow a strong bridging effect to interact with silicone rubber monomer,which,together with anti-agglomeration property of methyl groups,contributes to a pronounced improvement in mechanical performance of nanosilica-filled silicone rubber.Benefitting from the enhanced mechanical and barrier properties,the as-fabricated nanosilica-filled silicone rubber demonstrates superior protection for the encapsulated circuits with a significantly improved lifetime(709.1 h)compared to that of circuits coated by pure silicone rubber(472.8 h)and bare circuit boards(1 h),which offers great values for packaging material design in future IED encapsulation.展开更多
The effects of nanosilica（SiO2） on crystallization and thermal aging behaviors of polyethylene terephthalate（PET） have been studied using differential scanning calorimetry（DSC） and polarized optical microscopy（...The effects of nanosilica（SiO2） on crystallization and thermal aging behaviors of polyethylene terephthalate（PET） have been studied using differential scanning calorimetry（DSC） and polarized optical microscopy（POM）, viscometry, tensile testing and scanning electron microscopy（SEM）. For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 ℃, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.展开更多
This study examines the effect of nanosilica(NS)additive to improve the mechanical properties of clay,clayey sand,and sand.The engineering properties of the soils were investigated through Atterberg limits,compaction,...This study examines the effect of nanosilica(NS)additive to improve the mechanical properties of clay,clayey sand,and sand.The engineering properties of the soils were investigated through Atterberg limits,compaction,unconfined compression,ultrasonic pulse velocity(UPV),freeze-thaw,and direct shear tests.The NS content varied from 0%to 0.7%and cement content was 5%and 10%by the dry weight of the soil.The curing period varied from 7 d to 150 d.The consistency,compaction,and strength properties of the soils were affected by the presence of NS and cement.The optimum NS contents in clay specimens with 5%and 10%cement were 0.5%and 0.7%,respectively.It was 0.7%in sand specimens with both cement ratios,as well as 0.3%and 0.7%in clayey sand specimens with 5%and 10%cement,respectively.In terms of freeze-thaw resistance,clayey sand specimens containing 0.5%NS and 10%cement had the minimum strength loss.Exponential relationships existed between the ultrasonic pulse velocity(UPV)and the unconfined compressive strength(UCS)of soil specimens having the same curing period.The shear strength parameters of the soils also improved with the addition of NS.Scanning electron microscope(SEM)images demonstrated that cement and NS contributed to the improvement of the soils by producing a denser and more uniform structure.It was concluded that the minor addition of NS could potentially improve the geomechanical properties of the soils.展开更多
Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments.Herein,polyurethane was composited with polyaniline and nanosilica based on in sit...Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments.Herein,polyurethane was composited with polyaniline and nanosilica based on in situ synthesis of polymer and physical mixing of these fillers to reach desired antistatic and mechanical properties.Chemical,morphological and thermal properties of the polyurethane/polyaniline/nanosilica composites were studied.The electrical resistivity of the composite decreased from 1.1×10^(6)MΩto 7.6×10^(4)MΩas a result of the addition of 4%polyaniline.The tensile strength and elongation at break of the polyurethane composites improved by nearly 300%and100%,respectively,when compared with those of the neat polyurethane.The electronic resistance of PU/PANI/NS ternary is low enough for its antistatic property and decreases with the increase of the added nanosilica,which is unexpectedly and rather significant.Our results would shed light on the development of antistatic PU with excellent mechanical performance.展开更多
Graphene nanosheets （GS） were easily prepared through liquid-phase exfoliation of graphite powder in N,N-dimethylformamide （DMF） with the assistance of sodium citrate. Then, GS was coated onto a glassy carbon elec...Graphene nanosheets （GS） were easily prepared through liquid-phase exfoliation of graphite powder in N,N-dimethylformamide （DMF） with the assistance of sodium citrate. Then, GS was coated onto a glassy carbon electrode （GCE） surface by drop to fabricate a GS]GCE nanointerface. Subsequently, by using tetraethylorthosilicate sol as precursor, nanosilica was electrochemically deposited onto the GS]GCE surface to produce a nanocomposite film electrode （nanosilicaJGSJGCE）. Electrochemical behaviors of methyl parathion （MP） on the nanosilica/GS/GCE surface were investigated thoroughly. It was found that the nanosilicaJGS nanocomposites can improve the redox peak currents of MP significantly due to the synergetic effect. The oxidation peak current was linearly related to MP concentration in the range from 0.0005 μmol/L to 5.6 μmol/L. The detection limit was calculated to be 0.07 nmol/L （SJN = 3）. The developed method was used to determine MP in real samples. The recoveries were in the range from 95.4% to 104.2%, demonstrating satisfactory results.展开更多
The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) character...The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) characteristic were investigated.展开更多
To solve the energy consumption and CO_(2) emission during cement production,the new binders must be developed as an alternative to cement.CaO/CaSO_(4)-activated slag binder is an eco-friendly and safe cementitious ma...To solve the energy consumption and CO_(2) emission during cement production,the new binders must be developed as an alternative to cement.CaO/CaSO_(4)-activated slag binder is an eco-friendly and safe cementitious material;however,its low strength during initial stages limits its applications.In this study,colloidal nanosilica(CNS)was employed as an additive to improve the strength of CaO/CaSO_(4)-activated slag binder,and the effects of CNS on the workability,hydration kinetics,hydration products(type,quantity,and polymerization degree),and binder microstructure were thoroughly investigated.A moderate CNS content,through its nucleation effect,significantly increased the hydration rate of the nucleation and crystal growth(NG),phase boundary interaction(I)and diffusion(D)processes,which generated large quantities of calcium aluminosilicate hydrate(C-A-S-H)gel in the initial hydration stage.Meanwhile,the addition of CNS improved the polymerization degree of C-A-S-H gel.This amorphous reactant well-filled the pore space between slag particles and yielded a compact microstructure,consequently enhancing the binder strength.Considering the reduction in fluidity and the increase in production cost,the CNS mass fraction was controlled as3%,and the binder reached the satisfactory strengths of 3.87,24.47,31.43,and 41.78 MPa at 1,3,7,and 28 d,respectively.展开更多
Amide-and alkyl-modified nanosilicas(AANPs)were synthesized and introduced into Xanthan gum(XG)solution,aiming to improve the temperature/salt tolerance and oil recovery.The rheological behaviors of XG/AANP hybrid dis...Amide-and alkyl-modified nanosilicas(AANPs)were synthesized and introduced into Xanthan gum(XG)solution,aiming to improve the temperature/salt tolerance and oil recovery.The rheological behaviors of XG/AANP hybrid dispersions were systematically studied at different concentrations,temperatures and inorganic salts.At high temperature(75C)and high salinity(10,000 mg,L1 NaCl),AANPs increase the apparent viscosity and dynamic modulus of the XG solution,and XG/AANP hybrid dispersion exhibits elastic-dominant properties.The most effective concentrations of XG and AANP interacting with each other are 1750 mg·L^(-1) and 0.74 wt%,respectively.The temperature tolerance of XG solution is not satisfactory,and high temperature further weakens the salt tolerance of XG.However,the AANPs significantly enhance the viscoelasticity the XG solution through hydrogen bonds and hydrophobic effect.Under reservoir conditions,XG/AANP hybrid recovers approximately 18.5%more OOIP(original oil in place)than AANP and 11.3%more OOIP than XG.The enhanced oil recovery mechanism of the XG/AANP hybrid is mainly increasing the sweep coefficient,the contribution from the reduction of oil-water interfacial tension is less.展开更多
Oligochitosan (OC) with molecular weight Mw of 5000 g/mol was prepared by gamma Co-60 ray irradiation of chitosan solution. Nanosilica (nSiO2) with the size of 10 - 30 nm was synthesized by calcination of acid treated...Oligochitosan (OC) with molecular weight Mw of 5000 g/mol was prepared by gamma Co-60 ray irradiation of chitosan solution. Nanosilica (nSiO2) with the size of 10 - 30 nm was synthesized by calcination of acid treated rice husk. The mixture of 1% OC - 1% nSiO2 was prepared by dispersion of nSiO2 in OC solution. The morphology of nSiO2 in the mixture of OC-nSiO2 was measured from images of transmission electron microscopy (TEM). The effect of foliar application of the mixture of OC-nSiO2 on the induction of resistance against anthracnose disease caused by Colletotrichum gloeosporioides fungus on chili fruits was investigated. Results indicated that foliar application of OC-nSiO2 with the concentration of 60 mg/l - 60 mg/l was found to be as the optimal treatment that reduced the disease severity on chili fruits to 22.2% compared with 90.0% of the control. Thus, OC-nSiO2 hybrid material could be considered as an effective biotic elicitor to prevent anthracnose disease infection for chili fruits. Furthermore, the prepared OC-nSiO2 hybrid material can also be used as an environmentally friendly agrochemical product for sustainable development of agriculture.展开更多
The swelling dynamic and epoxy resin structure changes of nanosilica (NS) with different specific surface in concentrated nitric acid were studied. It is established that with increasing of specific surface area of un...The swelling dynamic and epoxy resin structure changes of nanosilica (NS) with different specific surface in concentrated nitric acid were studied. It is established that with increasing of specific surface area of unmodified NS swelling degree decreases and stability of the composite in the acid goes up. Resistance of NS to the HNO3 can be achieved by choosing the optimal concentration and modifications of NS’s surface. According to electron microscopy and X-ray diffraction, the structure of composite can be changed due to appearance of ordered structural zones.展开更多
Outdoor building stones are suffering from serious degradation.To restore internal cohesion and to alleviate the disintegration of decayed stones,consolidation treatment is necessary and significant.Up to date,no full...Outdoor building stones are suffering from serious degradation.To restore internal cohesion and to alleviate the disintegration of decayed stones,consolidation treatment is necessary and significant.Up to date,no fully satisfactory consolidation agent and its application methodology are available,mainly due to the limited penetration depth of consolidants,low compatibility,or poor durability in environmental conditions.Herein,in this study,aiming to design an effective and enduring method for the consolidation of highly porous calcareous stones,nanosilica-based consolidation treatments were tested and compared with traditional compounds(tetraethoxysilane,alkylalkoxysilane,barium hydroxide).In order to evaluate their performance and compatibility,a series of standard tests,including the Drilling Resistance Measurement System(DRMS)test,surface color measurement,vapor diffusivity measurement,and peeling test,were carried out.Besides,the penetration depth and distribution profiles of consolidants were estimated by exploiting elemental raster scanning of SEM-EDS analysis performed throughout the thickness of samples.More importantly,by employing a climatic chamber,the artificial ageing test was also conducted by simulating harsh atmospheric conditions.After accelerated ageing,the performance of all consolidants was assessed again.Results demonstrated that the application of nanosilica(<10 nm in dimension)by cellulose poultice,followed by adding tetraethoxysilane with the classical method“wet on wet”,is the best consolidation approach,in terms of in-depth consolidation efficacy,compatibility with the stone substrate,surface cohesion strength and performance durability in environmental conditions.Moreover,the treated surface is not hydrophobic,which allows further grouting and adhesion operations usually required for the restoration of historic buildings.展开更多
文摘According the importance of the stored grains and other products,it is an essential to keep them from khapra beetle,Trogoderma granarium infestation.This study determined the mortality percentage of 5th instar larvae of T.granarium fed on wheat seeds(25 gm)treated with different weights of silica as well as silica nanoparticles(20,40,60 and 80 mg)at different temperature(9℃,25℃,and 35℃).Study showed that using silica nanoparticles in cold temperature(9℃)was the most efficient treatment with the lowest LC_(50)(lethal concentration required to kill 50%of the population)value and caused the highest toxicity index.In contrast,the least efficient treatment(25℃)with the highest LC_(50) value and showed lowest toxicity index was using silica in normal temperature,when using silica nanoparticles,the cold temperature was the best condition followed by hot temperature(35℃)and finally the normal temperature.On the other hand,using silica in hot temperature was most effective followed by silica with cold temperature and finally silica with normal temperature.The biochemical assays revealed that the change in the experimental temperature had a nonsignificant effect on the total protein content of the larvae.The total lipids and total carbohydrates exhibited a significant increase due to hot treating.5th instar larvae of T.granarium treated with LC50 of silica at high temperature led to a nonsignificant(p≤0.05)decrease in Acetylcholinesterase(AchE)activity compared to treatment at normal temperature.In contrast,Glutathione S-transferase(GST)and Peroxidase activities were significantly(p≤0.05)raised due to the treatment conducted at high temperature.Additionally,treating larvae with LC50 of silica nanoparticles at low temperature caused a significant increase in both GST and peroxidase activities,while the increase in AChE was nonsignificantly(p≤0.05)compared to treatment at normal temperature.Using silica at low temperature could be used as an alternative to chemical insecticides to control T.granarium larvae.
基金supported by the National Natural Science Foundation for International Young Scientists of China(Grant No.52150410427)funding of Scientific Research Startup Project for High-Level Talents of Shandong Institute of Petroleum and Chemical Technology(Grant No.DJB2023020 and Grant No.2023SS019).
文摘Smart low-solid drilling fluids(SLSDFs)with thermo-controllable rheological properties and attractive thickening characteristics have recently captivated profound attention due to their low formation damage and enhanced cuttings lifting capacity.However,their applications to deep hole drilling at high temperatures have remained limited because of the thermal instability and environmental constraints of the thermo-associating polymers as additives.This work explored the synergistic benefits of thermo-associating polymer and biogenic nano-silica(B-SiNP)extracted from rice husk to improve the thermo-stability of SLSDF.This study shows that the nano-hybrid,TAP-S based on vinyl-terminated B-SiNP could potentially mitigate the limiting performance of conventional LSDF(F-2)caused by the failure of thermo-associating copolymers under elevated temperatures.TAP-S bearing drilling fluid(F-3)could preserve more than 5.6-fold of its initial properties(ca.apparent viscosity,plastic viscosity,yield point,and gel strength)with a nearly flat-gel profile in the temperature range of 25-230℃,which was higher than those of the counterpart F-2 and base fluid according to the results of rheological tests analysis.In addition,TAP-S exhibited an abrupt thermo-thickening characteristic with a magnitude declining by only 1.05-fold and the activation Gibbs free energy of 1339 kJ/mol above the plateau(ca.130℃),reflecting its less sensitivity compared to F-2 under a continuous heating process.As a result,a lower temperature was required to drive the dehydration of the residual fraction of lower critical solution temperature(LCST)in nano-hybrid structures than TAP according to the results of DSC analysis.Thus,lower energy was expected to disintegrate the residual hydrogen bonds formed between the LCST chains and surrounding water molecules at elevated temperatures.Moreover,TAP-S formed a solid-micro-crosslinking structure network which exhibited a more stable hydrodynamic diameter as revealed by DLS analysis.Compared with TAP,TAP-S consisted of a larger composite B-SiNP-TAP integrated spatial network structure based on the results of environmental scanning electron microscope,which conferred a degree of thermal conductivity characteristic for improved temperature resistance.This contributed to the effective binding onto bentonite particles for protection and maintained a relatively stable bentonite particle dispersion according to the results of EPM and particle size distribution analyses.Consequently,TAP-S fortified drilling fluid demonstrates improved rheological and filtration performance under severe downhole conditions.Therefore,TAP-S,the thermo-associating copolymer integrated with B-SiNP could find potential application as an eco-friendly viscosifier in LSDFs for deep-well drilling operations.
基金financially supported by the National Natural Science Foundation of China(Grant No.52150410427)the Key Support Program for Foreign Experts of the Ministry of Science and Technology of the People's Republic of China(No.wgxz2022057)funding for post-doctoral work by the Department of Human Resources and Social Security of Hubei Province。
文摘Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.
文摘An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy soil.Cement agent included Portland cement type II.Cement content was 6% by weight of the sandy soil.Nanosilica was added in percentages of 0%,4%,8% and 12% by weight of cement.Cylindrical samples were prepared with relative density of 80% and optimum water content and cured for 7 d,28 d and 90 d.Microstructure characteristics of cementnanosilica-sand mixtures after 90 d of curing have been explored using atomic force microscopy(AFM),scanning electron microscopy(SEM) and X-ray diffraction(XRD) tests.Effects of curing time on microstructure properties of cemented sandy soil samples with 0% and 8% nanosilica have been investigated using SEM test.Unconfined compression test(for all curing times) and compaction test were also performed.The SEM and AFM tests results showed that nanosilica contributes to enhancement of cemented sandy soil through yielding denser,more uniform structure.The XRD test demonstrated that the inclusion of nanosilica in the cemented soil increases the intensity of the calcium silicate hydrate(CSH) peak and decreases the intensity of the calcium hydroxide(CH) peak.The results showed that adding optimum percentages of nanosilica to cement-stabilized sandy soil enhances its mechanical and microstructure properties.
基金supported by the National Natural Science Foundation of China(Nos.21207099 and 21273162)Science and Technology Commission of Shanghai Municipality,China(Nos. 11nm0501000 and 12ZR1451100)Key Subject of Shanghai Municipal Education Commission(No.J50102)
文摘A novel synthesis of hierarchical porous carbons （HPCs）with 3D open-cell structure based on nanosilica- embedded emulsion-templated polymerization was reported. An oil-in-water emulsion containing SiO2 colloids was fabricated using liquid paraffin as an oil phase, resorcinol/formaldehyde and silica sol as an aqueous phase, and Span 80/Tween 80 as emulsifiers. HPCs with macropore cores, open meso/ macropore windows, and abundant micropores were synthesized by the polymerization and carbonization of the emulsion, followed by scaffold removal and further KOH activation. A typical HPCs sample as supercapacitor electrode shows the charge/discharge capability under large loading current density （30 A/g） coupling with a reasonable electrochemical capacitance in KOH electrolyte solution.
基金financial support of Department of Pharmaceutics, Faculty of Pharmacy, Kerman Medical Science University
文摘This paper describes the electrodeposition of polyphosphate-doped polypyrrole/nanosilica nano-composite coating on steel wire for direct solid-phase microextraction of bisphenol A and five phthalates. We optimized influencing parameters on the extraction efficiency and morphology of the nanocomposite such as deposition potential, concentration of pyrrole and polyphosphate, deposition time and the nanosilica amount. Under the optimized conditions, characterization of the nanocomposite was inves-tigated by scanning electron microscopy and Fourier transform infra-red spectroscopy. Also, the factors related to the solid-phase microextraction method including desorption temperature and time, extrac-tion temperature and time, ionic strength and pH were studied in detail. Subsequently, the proposed method was validated by gas chromatography-mass spectrometry by thermal desorption and acceptable figures of merit were obtained. The linearity of the calibration curves was between 0.01 and 50 ng/mL with acceptable correlation coefficients (0.9956-0.9987) and limits of detection were in the range 0.002-0.01 ng/mL. Relative standard deviations in terms of intra-day and inter-day by five replicate analyses from aqueous solutions containing 0.1 ng/mL of target analytes were in the range 3.3%-5.4% and 5%-7.1%, respectively. Fiber-to-fiber reproducibilities were measured for three different fibers prepared in the same conditions and the results were between 7.3% and 9.8%. Also, extraction recoveries at two different concentrations were ≥96%. Finally, the suitability of the proposed method was demonstrated through its application to the analysis of some eye drops and injection solutions.
基金supported by the National Natural Science Foundation of China(Nos.51871227 and 52271079).
文摘Implantable electronic devices(IEDs)are widely used by human beings to achieve medical treatment and diagnosis nowadays.However,ideal encapsulation of IEDs is still far from perfect as full prevention of body fluid diffusion into the coating remains unsolved.Herein,we develop a high-performance composite coating for IED encapsulation by introducing SiO_(2) nanoparticles into silicone rubber,which synergistically enhances mechanical properties and improves barrier performance.By fabricating composite coatings with different nanosilica contents,3%nanosilica is proved to be an optimal additive content with an excellent combination of improved fracture strength(from 2.5 MPa to 4.5 MPa),increased coating resistance(from 10^(4) to 10^(9) cm^(2))and ideal coating uniformity.Mechanical and electrochemical characterizations subsequently confirm substantially enhanced mechanical properties and barrier performance of the composite coating,which effectively resist crack propagation and impede penetrations of water and chloride ions through the coating.Theoretical calculations further uncover that modified SiO_(2) particles with enriched methyl groups endow a strong bridging effect to interact with silicone rubber monomer,which,together with anti-agglomeration property of methyl groups,contributes to a pronounced improvement in mechanical performance of nanosilica-filled silicone rubber.Benefitting from the enhanced mechanical and barrier properties,the as-fabricated nanosilica-filled silicone rubber demonstrates superior protection for the encapsulated circuits with a significantly improved lifetime(709.1 h)compared to that of circuits coated by pure silicone rubber(472.8 h)and bare circuit boards(1 h),which offers great values for packaging material design in future IED encapsulation.
基金financially supported by the Jiangsu Yuxing Film Technology Co.Ltd.,China
文摘The effects of nanosilica（SiO2） on crystallization and thermal aging behaviors of polyethylene terephthalate（PET） have been studied using differential scanning calorimetry（DSC） and polarized optical microscopy（POM）, viscometry, tensile testing and scanning electron microscopy（SEM）. For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 ℃, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.
基金The authors thank to Ege University Central Research Test and Analysis Laboratory Application and Research Center(EGE-MATAL)for SEM images.
文摘This study examines the effect of nanosilica(NS)additive to improve the mechanical properties of clay,clayey sand,and sand.The engineering properties of the soils were investigated through Atterberg limits,compaction,unconfined compression,ultrasonic pulse velocity(UPV),freeze-thaw,and direct shear tests.The NS content varied from 0%to 0.7%and cement content was 5%and 10%by the dry weight of the soil.The curing period varied from 7 d to 150 d.The consistency,compaction,and strength properties of the soils were affected by the presence of NS and cement.The optimum NS contents in clay specimens with 5%and 10%cement were 0.5%and 0.7%,respectively.It was 0.7%in sand specimens with both cement ratios,as well as 0.3%and 0.7%in clayey sand specimens with 5%and 10%cement,respectively.In terms of freeze-thaw resistance,clayey sand specimens containing 0.5%NS and 10%cement had the minimum strength loss.Exponential relationships existed between the ultrasonic pulse velocity(UPV)and the unconfined compressive strength(UCS)of soil specimens having the same curing period.The shear strength parameters of the soils also improved with the addition of NS.Scanning electron microscope(SEM)images demonstrated that cement and NS contributed to the improvement of the soils by producing a denser and more uniform structure.It was concluded that the minor addition of NS could potentially improve the geomechanical properties of the soils.
基金financially supported by Natural Science Advance Research Foundation of Shaanxi University of Science and Technology(No.2020XSGG-07)the National Natural Science Foundation of China(No.31570578)Key Research and Development Program of Shaanxi(No.2022GY-278)。
文摘Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments.Herein,polyurethane was composited with polyaniline and nanosilica based on in situ synthesis of polymer and physical mixing of these fillers to reach desired antistatic and mechanical properties.Chemical,morphological and thermal properties of the polyurethane/polyaniline/nanosilica composites were studied.The electrical resistivity of the composite decreased from 1.1×10^(6)MΩto 7.6×10^(4)MΩas a result of the addition of 4%polyaniline.The tensile strength and elongation at break of the polyurethane composites improved by nearly 300%and100%,respectively,when compared with those of the neat polyurethane.The electronic resistance of PU/PANI/NS ternary is low enough for its antistatic property and decreases with the increase of the added nanosilica,which is unexpectedly and rather significant.Our results would shed light on the development of antistatic PU with excellent mechanical performance.
基金supported by the National Natural Science Foundation of China (No. 21561011)Scientific and Technological Innovation Team Project of Hubei University for Nationalities (No. MY2014T004)the Open Foundation of Key Laboratory of Biologic Resources Protection and Utilization of Hubei Province (No. PKLHB1506)
文摘Graphene nanosheets （GS） were easily prepared through liquid-phase exfoliation of graphite powder in N,N-dimethylformamide （DMF） with the assistance of sodium citrate. Then, GS was coated onto a glassy carbon electrode （GCE） surface by drop to fabricate a GS]GCE nanointerface. Subsequently, by using tetraethylorthosilicate sol as precursor, nanosilica was electrochemically deposited onto the GS]GCE surface to produce a nanocomposite film electrode （nanosilicaJGSJGCE）. Electrochemical behaviors of methyl parathion （MP） on the nanosilica/GS/GCE surface were investigated thoroughly. It was found that the nanosilicaJGS nanocomposites can improve the redox peak currents of MP significantly due to the synergetic effect. The oxidation peak current was linearly related to MP concentration in the range from 0.0005 μmol/L to 5.6 μmol/L. The detection limit was calculated to be 0.07 nmol/L （SJN = 3）. The developed method was used to determine MP in real samples. The recoveries were in the range from 95.4% to 104.2%, demonstrating satisfactory results.
文摘The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) characteristic were investigated.
基金supported by Natural Science Foundation of Shandong Province(No.ZR2019BEE075)Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents(No.2019RCJJ007)+1 种基金Young Science and Technology Innovation Program of Shandong Province(No.2020KJD001)Youth Science and Technology Talent Growth Program of Guizhou Province(No.KY[2018]466).
文摘To solve the energy consumption and CO_(2) emission during cement production,the new binders must be developed as an alternative to cement.CaO/CaSO_(4)-activated slag binder is an eco-friendly and safe cementitious material;however,its low strength during initial stages limits its applications.In this study,colloidal nanosilica(CNS)was employed as an additive to improve the strength of CaO/CaSO_(4)-activated slag binder,and the effects of CNS on the workability,hydration kinetics,hydration products(type,quantity,and polymerization degree),and binder microstructure were thoroughly investigated.A moderate CNS content,through its nucleation effect,significantly increased the hydration rate of the nucleation and crystal growth(NG),phase boundary interaction(I)and diffusion(D)processes,which generated large quantities of calcium aluminosilicate hydrate(C-A-S-H)gel in the initial hydration stage.Meanwhile,the addition of CNS improved the polymerization degree of C-A-S-H gel.This amorphous reactant well-filled the pore space between slag particles and yielded a compact microstructure,consequently enhancing the binder strength.Considering the reduction in fluidity and the increase in production cost,the CNS mass fraction was controlled as3%,and the binder reached the satisfactory strengths of 3.87,24.47,31.43,and 41.78 MPa at 1,3,7,and 28 d,respectively.
基金We gratefully acknowledge financial supports from the Major Program of National Natural Science Foundation of China(Grant No.42090024)the National Natural Science Foundation of China(Grant No.52004322)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020QE108).
文摘Amide-and alkyl-modified nanosilicas(AANPs)were synthesized and introduced into Xanthan gum(XG)solution,aiming to improve the temperature/salt tolerance and oil recovery.The rheological behaviors of XG/AANP hybrid dispersions were systematically studied at different concentrations,temperatures and inorganic salts.At high temperature(75C)and high salinity(10,000 mg,L1 NaCl),AANPs increase the apparent viscosity and dynamic modulus of the XG solution,and XG/AANP hybrid dispersion exhibits elastic-dominant properties.The most effective concentrations of XG and AANP interacting with each other are 1750 mg·L^(-1) and 0.74 wt%,respectively.The temperature tolerance of XG solution is not satisfactory,and high temperature further weakens the salt tolerance of XG.However,the AANPs significantly enhance the viscoelasticity the XG solution through hydrogen bonds and hydrophobic effect.Under reservoir conditions,XG/AANP hybrid recovers approximately 18.5%more OOIP(original oil in place)than AANP and 11.3%more OOIP than XG.The enhanced oil recovery mechanism of the XG/AANP hybrid is mainly increasing the sweep coefficient,the contribution from the reduction of oil-water interfacial tension is less.
文摘Oligochitosan (OC) with molecular weight Mw of 5000 g/mol was prepared by gamma Co-60 ray irradiation of chitosan solution. Nanosilica (nSiO2) with the size of 10 - 30 nm was synthesized by calcination of acid treated rice husk. The mixture of 1% OC - 1% nSiO2 was prepared by dispersion of nSiO2 in OC solution. The morphology of nSiO2 in the mixture of OC-nSiO2 was measured from images of transmission electron microscopy (TEM). The effect of foliar application of the mixture of OC-nSiO2 on the induction of resistance against anthracnose disease caused by Colletotrichum gloeosporioides fungus on chili fruits was investigated. Results indicated that foliar application of OC-nSiO2 with the concentration of 60 mg/l - 60 mg/l was found to be as the optimal treatment that reduced the disease severity on chili fruits to 22.2% compared with 90.0% of the control. Thus, OC-nSiO2 hybrid material could be considered as an effective biotic elicitor to prevent anthracnose disease infection for chili fruits. Furthermore, the prepared OC-nSiO2 hybrid material can also be used as an environmentally friendly agrochemical product for sustainable development of agriculture.
文摘The swelling dynamic and epoxy resin structure changes of nanosilica (NS) with different specific surface in concentrated nitric acid were studied. It is established that with increasing of specific surface area of unmodified NS swelling degree decreases and stability of the composite in the acid goes up. Resistance of NS to the HNO3 can be achieved by choosing the optimal concentration and modifications of NS’s surface. According to electron microscopy and X-ray diffraction, the structure of composite can be changed due to appearance of ordered structural zones.
基金supported by Provincia Veneta dell’Ordine dei Carmelitani Scalzi through the Special allocation grant(CNR-IGG Prot.N.0001882)the National Natural Science Foundation of China(Grant No.52202028)“the Belt and Road”Innovation Talent Exchange Program for Foreign Experts(Grant No.DL2021183001L)。
文摘Outdoor building stones are suffering from serious degradation.To restore internal cohesion and to alleviate the disintegration of decayed stones,consolidation treatment is necessary and significant.Up to date,no fully satisfactory consolidation agent and its application methodology are available,mainly due to the limited penetration depth of consolidants,low compatibility,or poor durability in environmental conditions.Herein,in this study,aiming to design an effective and enduring method for the consolidation of highly porous calcareous stones,nanosilica-based consolidation treatments were tested and compared with traditional compounds(tetraethoxysilane,alkylalkoxysilane,barium hydroxide).In order to evaluate their performance and compatibility,a series of standard tests,including the Drilling Resistance Measurement System(DRMS)test,surface color measurement,vapor diffusivity measurement,and peeling test,were carried out.Besides,the penetration depth and distribution profiles of consolidants were estimated by exploiting elemental raster scanning of SEM-EDS analysis performed throughout the thickness of samples.More importantly,by employing a climatic chamber,the artificial ageing test was also conducted by simulating harsh atmospheric conditions.After accelerated ageing,the performance of all consolidants was assessed again.Results demonstrated that the application of nanosilica(<10 nm in dimension)by cellulose poultice,followed by adding tetraethoxysilane with the classical method“wet on wet”,is the best consolidation approach,in terms of in-depth consolidation efficacy,compatibility with the stone substrate,surface cohesion strength and performance durability in environmental conditions.Moreover,the treated surface is not hydrophobic,which allows further grouting and adhesion operations usually required for the restoration of historic buildings.
