The incorporation of heteroatoms into carbon aerogels(CAs)can lead to structural distortions and changes in active sites due to their smaller size and electronegativity compared to pure carbon.However,the evolution of...The incorporation of heteroatoms into carbon aerogels(CAs)can lead to structural distortions and changes in active sites due to their smaller size and electronegativity compared to pure carbon.However,the evolution of the electronic structure from single-atom doping to heteroatom codoping in CAs has not yet been thoroughly investigated,and the impact of codoping on potassium ion(K+)storage and diffusion pathways as electrode material remains unclear.In this study,experimental and theoretical simulations were conducted to demonstrate that heteroatom codoping,composed of multiple heteroatoms(O/N/B)with different properties,has the potential to improve the electrical properties and stability of CAs compared to single-atom doping.Electronic states near the Fermi level have revealed that doping with O/N/B generates a greater number of active centers on adjacent carbon atoms than doping with O and O/N atoms.As a result of synergy with enhanced wetting ability(contact angle of 9.26°)derived from amino groups and hierarchical porous structure,ON-CA has the most optimized adsorption capacity(−1.62 eV)and diffusion barrier(0.12 eV)of K^(+).The optimal pathway of K^(+)in ON-CA is along the carbon ring with N or O doping.As K^(+)storage material for supercapacitors and ion batteries,it shows an outstanding specific capacity and capacitance,electrochemical stability,and rate performance.Especially,the assembled symmetrical K^(+)supercapacitor demonstrates an energy density of 51.8 Wh kg^(−1),an ultrahigh power density of 443Wkg^(−1),and outstanding cycling stability(maintaining 83.3%after 10,000 cycles in 1M KPF6 organic electrolyte).This research provides valuable insights into the design of highperformance potassium ion storage materials.展开更多
Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to...Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.展开更多
The 3D shape-changing hydrogels are highly pursued for numerous applications.However,up to now,the construction of complex 3D shape-changing hydrogels remains a challenge.The reported design strategies are mainly appl...The 3D shape-changing hydrogels are highly pursued for numerous applications.However,up to now,the construction of complex 3D shape-changing hydrogels remains a challenge.The reported design strategies are mainly applied to fabricate 2D ones by introducing anisotropic microstructures into hydrogel sheets/membranes.Herein,we present a convenient photolithography strategy for constructing complex 3D shape-changing hydrogels by simultaneously modulating anisotropic microstructures and internal stress fields of gel sheets.When the precursor solution containing ultraviolet(UV)absorber is irradiated by single-side UV light,the attenuated polymerization rate can cause the generation of asymmetric internal stress field in the resulting hydrogel sheet.In the meantime,the directional diffusion of unpolymerized monomers allows for the formation of vertical gradient structure within hydrogel.Therefore,by applying different photomasks to modulate the local gradient structures and internal stress fields of the gel sheets,they can spontaneously transform into various complex 3D shape-changing hydrogels in the air.Response to the external stimuli,these 3D shape-changing hydrogels(e.g.,fighter plane,birdie,and multi-storey origami lattices)can deform in a novel 3D_(1)-to-3D_(2)-to-3D_(3)mode.This new design strategy contributes to the development of complex biomedical implants and soft robotics.展开更多
In this study, polyethylene-terephthalate (PET) nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration int...In this study, polyethylene-terephthalate (PET) nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration into the nonwovens are investigated. The result indicates that the method can improve the wettability of PET nonwovens remarkably, but the aging decay of the sample's wettability is found to be notable as a function of the storage time after treatment due to the internal rotation of the single bond of surface macromolecules. As shown by SEM and XPS analysis, the etching and surface reaction are significant, and water-penetration weight is found to increase remarkably with the increasing power. This variation can be attributed to momentum transfer and enhanced higher-energy particle excitation.展开更多
The paper presents a detailed analysis of ordinary and dark energy density of the cosmos based on two different but complimentary theories. First, and starting from the concept of the speed of light being an average o...The paper presents a detailed analysis of ordinary and dark energy density of the cosmos based on two different but complimentary theories. First, and starting from the concept of the speed of light being an average over multi-fractals, we use Magueijo-Smolin’s ingenious revision of Einstein’s special relativity famous formula E = mc2 to a doubly special formula which includes the Planck energy as invariant to derive the ordinary energy density E(O) = mc2/22 and the dark energy density E(D) = mc2(21/22) wheremis the mass andcis the speed of light. Second we use the topological theory of pure gravity to reach the same result thus confirming the correctness of the theory of varying speed of light as well as the COBE, WMAP and Type 1a supernova cosmological measurements.展开更多
To overcome the ever-growing organic pollutions in the water system,abundant efforts have been dedicated to fabricating efficient Fenton-like carbon catalysts.However,the rational design of carbon catalysts with high ...To overcome the ever-growing organic pollutions in the water system,abundant efforts have been dedicated to fabricating efficient Fenton-like carbon catalysts.However,the rational design of carbon catalysts with high intrinsic activity remains a long-term goal.Herein,we report a new N-molecule-assisted self-catalytic carbonization process in augmenting the intrinsic Fenton-like activity of metal-organic-framework-derived carbon hybrids.During carbonization,the N-molecules provide alkane/ammonia gases and the formed iron nanocrystals act as the in situ catalysts,which result in the elaborated formation of carbon nanotubes(in situ chemical vapor deposition from alkane/iron catalysts)and micro-/meso-porous structures(ammonia gas etching).The obtained catalysts exhibited with abundant Fe/Fe-Nx/pyridinic-N active species,micro-/meso-porous structures,and conductive carbon nanotubes.Consequently,the catalysts exhibit high efficiency toward the degradation of different organic pollutions,such as bisphenol A,methylene blue,and tetracycline.This study not only creates a new pathway for achieving highly active Fenton-like carbon catalysts but also takes a step toward the customized production of advanced carbon hybrids for diverse energy and environmental applications.展开更多
Recently, in response to the major challenges in energy development and environmental issues, tremendous efforts are being devoted to developing electrochemical energy storage devices based on green sustainable resour...Recently, in response to the major challenges in energy development and environmental issues, tremendous efforts are being devoted to developing electrochemical energy storage devices based on green sustainable resources. As a class of green materials, nanocellulose(NC) has received extensive attention. In this review, we summarize the research progress of NC derived materials in electrochemical energy storage. Specifically, we first introduce various synthesis methods based on NC and the pretreatment process to increase the conductivity. Then we focus on the specific application of NC in electrochemical energy storage devices. Finally, we summarize the previously reported work and put forward views on the further development of NC in the field of electrochemical energy storage.展开更多
We collect 1974 broad-band velocity records of 94 earthquakes (ML=2.84.9, △=13462 km) from seven stations of the Fujian Seismic Network from March 1999 to March 2007. Using real-time simulation, we obtain the corresp...We collect 1974 broad-band velocity records of 94 earthquakes (ML=2.84.9, △=13462 km) from seven stations of the Fujian Seismic Network from March 1999 to March 2007. Using real-time simulation, we obtain the corresponding acceleration and then adopt different models to analyze the seismic data. As a result, a new attenuation relationship between PGA and PGV of the small and moderate earthquakes on bedrock site in Fujian region is established. The Yongchun earthquake occurred recently verifies the attenuation relationship well. This paper provides a new approach for studying the ground motion attenuation relationship using velocity records.展开更多
Membrane-based separation processes are new technology combined membrane separation with conventional separation. Hydrophobic porous membranes are often used in these processes. The structure of hydrophobic porous mem...Membrane-based separation processes are new technology combined membrane separation with conventional separation. Hydrophobic porous membranes are often used in these processes. The structure of hydrophobic porous membrane has significant effect on mass transfer process. The permeabilities of five kinds of gas, He, N2, O2, CO2 and water vapor, across six polytetrafluoroethylene(PTFE) flat membranes were tested experimentally. Results indicated that the greater the membrane mean pore size and the wider the pore size distribution are, the higher the gas permeability. A gas permeation model, including the effects of membrane structure parameter and gas properties, was established. A comprehensive characteristic parameter (including porosity, thickness and tortuosity) was found more effective to express the influence of membrane structure in gas permeation process. The predicted permeation coefficients were in good agreement with experimental data.展开更多
Layered double hydroxides(LDHs)have a special structure and atom composition,which are expected to be an excellent electromagnetic wave(EMW)absorber.However,it is still a problem that obtaining excellent EMWabsorbing ...Layered double hydroxides(LDHs)have a special structure and atom composition,which are expected to be an excellent electromagnetic wave(EMW)absorber.However,it is still a problem that obtaining excellent EMWabsorbing materials from LDHs.Herein,we designed heterostructure NiCo-LDHs@ZnO nanorod and then subsequent heat treating to derive NiCo@C/ZnO composites.Finally,with the synergy of excellent dielectric loss and magnetic loss,an outstanding absorption performance could be achieved with the reflection loss of−60.97 dB at the matching thickness of 2.3 mm,and the widest absorption bandwidth of 6.08 GHz was realized at 2.0 mm.Moreover,this research work provides a reference for the development and utilization of LDHs materials in the field of microwave absorption materials and can also provide ideas for the design of layered structural absorbers.展开更多
The phenomenon of a material failure varies with its gauge length in use. In the present study, the breaking strengths of J30/C70 and J55/C45 blended yarns spun by the ring spinning technology were investigated with ...The phenomenon of a material failure varies with its gauge length in use. In the present study, the breaking strengths of J30/C70 and J55/C45 blended yarns spun by the ring spinning technology were investigated with the employment of the equations derived from the Weibull theory. The four probability estimators of the Weibull distribution were also evaluated. The results showed that the estimator (2a) was acceptable for calculating the Weibull modulus of the jute/cotton blended yarns. With the exception of breaking strength of the J30/C70 at the gauge length of 200 ram, the breaking strengths of both blended yarn could be predicted accurately by the Eqs. (9) or (10) in this paper.展开更多
Water splitting,as an advanced energy conversion technology,consists of two half reactions,including oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).However,the ideal electrocatalysts are noble meta...Water splitting,as an advanced energy conversion technology,consists of two half reactions,including oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).However,the ideal electrocatalysts are noble metal based catalysts.Their high cost and scarcity in earth seriously restrict the large deployments.Ni Fe-based materials have attracted great attention in recent years due to their excellent catalytic properties for OER and HER.Nevertheless,their conductivity and electrochemical stability at high current density are unsatisfactory,resulting in ineffective water splitting due to high impedance and low stability.Recently,a series of catalysts coating Ni Fe-based materials on 3 D nickel foam were found to be extremely stable under the circumstance of high current density.In this review,we summarized the recent advances of NiFe-based materials on nickel foam for OER and HER,respectively,and further provided the perspectives for their future development.展开更多
Waterborne elastic polyester (WEP) with different content of hard polyester was applied in the maize starch (MS) based composites (MS/WEP) via solution casting method.The effects of WEP with different contents of hard...Waterborne elastic polyester (WEP) with different content of hard polyester was applied in the maize starch (MS) based composites (MS/WEP) via solution casting method.The effects of WEP with different contents of hard polyester on the structure and properties of starch were studied by Fourier transform infrared,X-ray diffraction,ultraviolet-visible,tensile test,differential scanning calorimeter,thermogravimetric analysis and moisture measurement.The experimental results show that the addition of WEP does not change the crystalline type of starch,and only reduces the crystallinity of starch.And the structure and properties of MS/WEP are related to not only the content of starch but also the microstructure of WEP or the content of hard polyester in WEP.Waterborne elastic polyester with 30wt% hard polyester (WEP30) has the best modification effect on the maize starch among all the WEPs.For example,MS/WEP30 film has the optimum toughness,aging resistance and transmittance,the lowest crystallinity and glass transition temperature among all the MS/WEP films,and the lower moisture content.It is related to the compatibility between starch and WEP,resulting from the number of physical crosslinking points in WEP..展开更多
The effects of coagulation conditions on tensile properties of the regenerated cellulose fibers prepared by wet-spinning from NaOH/thiourea/urea(8∶6.5∶8 by weight)aqueous solvent were investigated by tensile tester,...The effects of coagulation conditions on tensile properties of the regenerated cellulose fibers prepared by wet-spinning from NaOH/thiourea/urea(8∶6.5∶8 by weight)aqueous solvent were investigated by tensile tester,X-ray diffraction(XRD),and scanning electron microscope(SEM).The results show that the tensile properties of the as-spun fibers change with the coagualtion concentration,temperature,and time.When the spinning solution is coagulated in 10% H2SO4/12.5% Na2SO4 aqueous solution,the as-spun fibers have a typical structure of cellulose II,a circular cross-section,and homogeneous morphological structure.展开更多
Cellulose pulps were directly dissolved in a green solvent of sodium hydrate/urea/thiourea/water with different composition for the purpose to prepare new regenerated cellulose fibers or films. The results showed that...Cellulose pulps were directly dissolved in a green solvent of sodium hydrate/urea/thiourea/water with different composition for the purpose to prepare new regenerated cellulose fibers or films. The results showed that the highest solubility of cellulose in the solvent with the composition of 8/8/6.5/77.5. The results revealed that the pulp feeding sequence, stirring rate, pre-treatment of pulp and pulp size affected the cellulose concentration in the green solvent. Accordingly, the more effective dissolution method was proposed in order to get higher concentration of cellulose. Furthermore, the properties of solution prepared by different kinds of pulps in the solvent were investigated by ARES rheometer. Rheologieal analyses indicated that all cellulose aqueous solutions in their high concentration were pseudoplastic fluids and sensitive to temperature and tended to transform to gel when temperature increased.展开更多
A series of segmented polyether-polyester polyurethane with amorphous hydrophilic soft segment domains were prepared from 4,4'- diphenylmethane diisocyanate (MDI), polybutylene adipate (Glycol) 2000 (PBA2000), and...A series of segmented polyether-polyester polyurethane with amorphous hydrophilic soft segment domains were prepared from 4,4'- diphenylmethane diisocyanate (MDI), polybutylene adipate (Glycol) 2000 (PBA2000), and polyethylene glycol 1000 (PEG1000), with 1,4-butanediol (BDO) as the chain extender. Furthermore, several representative properties of the polyurethanes, such as moisture permeability, water resistance, hydrophilic property, and phase inversion temperature, were investigated. The studies show that the structure and concentration of soft segment have a remarkable effect on the main application properties of polyurethane. On the contrary, the functional properties of the polyurethane are almost not affected by its hard segment.展开更多
Without any preprocessing,polyester fabric has lower ability to hold on water and inks due to the smooth morphology of polyester fibers. Therefore, patterns directly printed with pigment inks have poor color yields an...Without any preprocessing,polyester fabric has lower ability to hold on water and inks due to the smooth morphology of polyester fibers. Therefore, patterns directly printed with pigment inks have poor color yields and bleed easily. Pretreatments of polyester fabric were carried out with atmospheric air plasma under different experimental conditions. After plasma treatment the samples were printed with magenta pigment ink. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses indicated that the enhanced color performance was mainly contributed by not only the etching effect but also oxygen-containing polar groups induced onto fiber surfaces through plasma treatment. Thereby the surface modification of polyester fabrics using atmospheric-pressure air plasma offers a potential way to fabric pretreatment for pigment inkjet printing with the advantages of environmental friendly and energy saving over traditional pretreatment methods.展开更多
The feasibility of combination process of jute degumming and bleaching with alkali-hydrogen peroxide in one-step-one-bath was discussed. The combination process basically has the similar function as the traditional tw...The feasibility of combination process of jute degumming and bleaching with alkali-hydrogen peroxide in one-step-one-bath was discussed. The combination process basically has the similar function as the traditional two-step-two-bath method. The factors such as hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration, treatment time and temperature were studied respectively, and then an orthogonal experiment was designed to study the interactions among the hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration. After the designed experiments, the optimum treatment conditions were obtained as follows: hydrogen peroxide of 12g/L, sodium hydroxide of 4g/L, CBI of 4g/L, JFC of 1g/L, treatment time of 60min and temperature of 75℃.展开更多
A plasticizer triethylene glycol maleate(TEG-MA) was synthesized. The dominated monoester of moderate hydrophobicity with apparent oil-water partition coefficient of 0.042 in the product was confirmed by acid value ...A plasticizer triethylene glycol maleate(TEG-MA) was synthesized. The dominated monoester of moderate hydrophobicity with apparent oil-water partition coefficient of 0.042 in the product was confirmed by acid value determination, HPLC and FTIR. Its plasticizing effect on oxidized starch was manifested by crystallization, aging behaviour, moisture absorption, and mechanical performance. X-ray diffraction data showed that the relative crystallinity of the plasticized starch decreased. Both the crystal and the crystallinity of starch films were rarely changed in aging. Moisture absorption relied on the ester content and relative humidity. The elongation at break increased significantly with plasticizer content more than 10% in the matrix.展开更多
Background:The few previous studies that focused on the effects of compression garments(CG)on distance running performance have simultaneously measured electromyogram,physiological,and perceptual parameters.Therefore,...Background:The few previous studies that focused on the effects of compression garments(CG)on distance running performance have simultaneously measured electromyogram,physiological,and perceptual parameters.Therefore,this study investigated the effects of CG on muscle activation and median frequency during and after distance running,as well as blood-lactate concentration and rating of perceived exertion(RPE)during distance running.Methods:Eight healthy male recreational runners were recruited to randomly perform two 40 min treadmill running trials,one with CG,and the other with control garment made of normal cloth.The RPE and the surface electromyography(EMG)of 5 lower extremity muscles including gluteus maximus(GM),rectus femoris(RF),semitendinosus(ST),tibialis anterior(TA),and gastrocnemius(GAS)were measured during the running trial.The blood-lactate levels before and after the running trial were measured.Results:Wearing CG led to significant lower muscle activation(p<0.05)in the GM(decreased 7.40%-14.31%),RF(decreased 4.39%-4.76%),and ST(decreased 3.42%-7.20%)muscles;moreover,significant higher median frequency(p<0.05)in the GM(increased 5.57%)and ST(increased 10.58%)muscles.Wearing CG did not alter the RPE values or the blood-lactate levels(p>0.05).Conclusion:Wearing CG was associated with significantly lower muscle activation and higher median frequency in the running-related key muscles during distance running.This finding suggested that wearing CG may improve muscle function,which might enhance running performance and prevent muscle fatigue.展开更多
基金financially supported by the Natural Science Foundation of China(Grant No.22005165)the Major Science and Technology Innovation Project of Shandong(Grant No.2019JZZY010507)+1 种基金the Qingdao Municipal Science and Technology Bureau(Grant No.17-1-1-86-jch)the Key Technology Research and Development Program of Shandong(Grant No.2018GGX108005).
文摘The incorporation of heteroatoms into carbon aerogels(CAs)can lead to structural distortions and changes in active sites due to their smaller size and electronegativity compared to pure carbon.However,the evolution of the electronic structure from single-atom doping to heteroatom codoping in CAs has not yet been thoroughly investigated,and the impact of codoping on potassium ion(K+)storage and diffusion pathways as electrode material remains unclear.In this study,experimental and theoretical simulations were conducted to demonstrate that heteroatom codoping,composed of multiple heteroatoms(O/N/B)with different properties,has the potential to improve the electrical properties and stability of CAs compared to single-atom doping.Electronic states near the Fermi level have revealed that doping with O/N/B generates a greater number of active centers on adjacent carbon atoms than doping with O and O/N atoms.As a result of synergy with enhanced wetting ability(contact angle of 9.26°)derived from amino groups and hierarchical porous structure,ON-CA has the most optimized adsorption capacity(−1.62 eV)and diffusion barrier(0.12 eV)of K^(+).The optimal pathway of K^(+)in ON-CA is along the carbon ring with N or O doping.As K^(+)storage material for supercapacitors and ion batteries,it shows an outstanding specific capacity and capacitance,electrochemical stability,and rate performance.Especially,the assembled symmetrical K^(+)supercapacitor demonstrates an energy density of 51.8 Wh kg^(−1),an ultrahigh power density of 443Wkg^(−1),and outstanding cycling stability(maintaining 83.3%after 10,000 cycles in 1M KPF6 organic electrolyte).This research provides valuable insights into the design of highperformance potassium ion storage materials.
基金supported by the National Natural Science Foundation of China (22278231,22005165 and 22376110)the Natural Science Foundation Project of Shandong Province (ZR2022MB092 and ZR2023ME098)the Taishan Scholar Program (ts201712030)。
文摘Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.
基金supported by the National Natural Science Foundation of China(52003133,51573080,51873094)the Key Research and Development Project of Shandong Province(2016GGX102005)+1 种基金the Technology Development Project of Shinan District of Qingdao(2018-4-007-ZH)the Program for Taishan Scholar of Shandong Province,State Key Laboratory of Bio-Fibers and Eco-Textiles,Qingdao University(G2RC202024,ZDKT202006).
文摘The 3D shape-changing hydrogels are highly pursued for numerous applications.However,up to now,the construction of complex 3D shape-changing hydrogels remains a challenge.The reported design strategies are mainly applied to fabricate 2D ones by introducing anisotropic microstructures into hydrogel sheets/membranes.Herein,we present a convenient photolithography strategy for constructing complex 3D shape-changing hydrogels by simultaneously modulating anisotropic microstructures and internal stress fields of gel sheets.When the precursor solution containing ultraviolet(UV)absorber is irradiated by single-side UV light,the attenuated polymerization rate can cause the generation of asymmetric internal stress field in the resulting hydrogel sheet.In the meantime,the directional diffusion of unpolymerized monomers allows for the formation of vertical gradient structure within hydrogel.Therefore,by applying different photomasks to modulate the local gradient structures and internal stress fields of the gel sheets,they can spontaneously transform into various complex 3D shape-changing hydrogels in the air.Response to the external stimuli,these 3D shape-changing hydrogels(e.g.,fighter plane,birdie,and multi-storey origami lattices)can deform in a novel 3D_(1)-to-3D_(2)-to-3D_(3)mode.This new design strategy contributes to the development of complex biomedical implants and soft robotics.
文摘In this study, polyethylene-terephthalate (PET) nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration into the nonwovens are investigated. The result indicates that the method can improve the wettability of PET nonwovens remarkably, but the aging decay of the sample's wettability is found to be notable as a function of the storage time after treatment due to the internal rotation of the single bond of surface macromolecules. As shown by SEM and XPS analysis, the etching and surface reaction are significant, and water-penetration weight is found to increase remarkably with the increasing power. This variation can be attributed to momentum transfer and enhanced higher-energy particle excitation.
文摘The paper presents a detailed analysis of ordinary and dark energy density of the cosmos based on two different but complimentary theories. First, and starting from the concept of the speed of light being an average over multi-fractals, we use Magueijo-Smolin’s ingenious revision of Einstein’s special relativity famous formula E = mc2 to a doubly special formula which includes the Planck energy as invariant to derive the ordinary energy density E(O) = mc2/22 and the dark energy density E(D) = mc2(21/22) wheremis the mass andcis the speed of light. Second we use the topological theory of pure gravity to reach the same result thus confirming the correctness of the theory of varying speed of light as well as the COBE, WMAP and Type 1a supernova cosmological measurements.
基金supported by the National Key R&D Program of China(2019YFA0110600 and 2019YFA0110601)National Natural Science Foundation of China(Nos.51603134,51903178,51803134,and 51703141)+1 种基金Sichuan Province’s Science and Technology Planning Project(No.2016GZ0350)the Postgraduate Course Construction Project of Sichuan University(No.2017KCSJ036)and for their financial support.
文摘To overcome the ever-growing organic pollutions in the water system,abundant efforts have been dedicated to fabricating efficient Fenton-like carbon catalysts.However,the rational design of carbon catalysts with high intrinsic activity remains a long-term goal.Herein,we report a new N-molecule-assisted self-catalytic carbonization process in augmenting the intrinsic Fenton-like activity of metal-organic-framework-derived carbon hybrids.During carbonization,the N-molecules provide alkane/ammonia gases and the formed iron nanocrystals act as the in situ catalysts,which result in the elaborated formation of carbon nanotubes(in situ chemical vapor deposition from alkane/iron catalysts)and micro-/meso-porous structures(ammonia gas etching).The obtained catalysts exhibited with abundant Fe/Fe-Nx/pyridinic-N active species,micro-/meso-porous structures,and conductive carbon nanotubes.Consequently,the catalysts exhibit high efficiency toward the degradation of different organic pollutions,such as bisphenol A,methylene blue,and tetracycline.This study not only creates a new pathway for achieving highly active Fenton-like carbon catalysts but also takes a step toward the customized production of advanced carbon hybrids for diverse energy and environmental applications.
基金financial support by the National Natural Science Foundation of China (grant no. 51808303, 51672143 and 31870535)Outstanding Youth of Natural Science in Shandong Province (JQ201713)Taishan Scholars Program and ARC Discovery Project (No. 170103317)。
文摘Recently, in response to the major challenges in energy development and environmental issues, tremendous efforts are being devoted to developing electrochemical energy storage devices based on green sustainable resources. As a class of green materials, nanocellulose(NC) has received extensive attention. In this review, we summarize the research progress of NC derived materials in electrochemical energy storage. Specifically, we first introduce various synthesis methods based on NC and the pretreatment process to increase the conductivity. Then we focus on the specific application of NC in electrochemical energy storage devices. Finally, we summarize the previously reported work and put forward views on the further development of NC in the field of electrochemical energy storage.
基金Joint Seismological Science Foundation of China (105034)
文摘We collect 1974 broad-band velocity records of 94 earthquakes (ML=2.84.9, △=13462 km) from seven stations of the Fujian Seismic Network from March 1999 to March 2007. Using real-time simulation, we obtain the corresponding acceleration and then adopt different models to analyze the seismic data. As a result, a new attenuation relationship between PGA and PGV of the small and moderate earthquakes on bedrock site in Fujian region is established. The Yongchun earthquake occurred recently verifies the attenuation relationship well. This paper provides a new approach for studying the ground motion attenuation relationship using velocity records.
基金Supported by the 863 Hi-Tech. Research and Development Program of China (No. 2002AA649280, No. 2002AA304030),National Natural Science Foundation of China (No. 20206002), Beijing NOVA program (H013610250112), University Doctor Science Foundation of China
文摘Membrane-based separation processes are new technology combined membrane separation with conventional separation. Hydrophobic porous membranes are often used in these processes. The structure of hydrophobic porous membrane has significant effect on mass transfer process. The permeabilities of five kinds of gas, He, N2, O2, CO2 and water vapor, across six polytetrafluoroethylene(PTFE) flat membranes were tested experimentally. Results indicated that the greater the membrane mean pore size and the wider the pore size distribution are, the higher the gas permeability. A gas permeation model, including the effects of membrane structure parameter and gas properties, was established. A comprehensive characteristic parameter (including porosity, thickness and tortuosity) was found more effective to express the influence of membrane structure in gas permeation process. The predicted permeation coefficients were in good agreement with experimental data.
基金This work was financially supported by the National Natural Science Foundation of China(No.51407134)Natural Science Foundation of Shandong Province(No.ZR2019YQ24)+3 种基金Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)China Postdoctoral Science Foundation(No.2016M590619)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)The authors acknowledge the support from The Thousand Talents Plan,The World-Class University and Discipline,The Taishan Scholar’s Advantageous and Distinctive Discipline Program of Shandong Province and The World-Class Discipline Program of Shandong Province.
文摘Layered double hydroxides(LDHs)have a special structure and atom composition,which are expected to be an excellent electromagnetic wave(EMW)absorber.However,it is still a problem that obtaining excellent EMWabsorbing materials from LDHs.Herein,we designed heterostructure NiCo-LDHs@ZnO nanorod and then subsequent heat treating to derive NiCo@C/ZnO composites.Finally,with the synergy of excellent dielectric loss and magnetic loss,an outstanding absorption performance could be achieved with the reflection loss of−60.97 dB at the matching thickness of 2.3 mm,and the widest absorption bandwidth of 6.08 GHz was realized at 2.0 mm.Moreover,this research work provides a reference for the development and utilization of LDHs materials in the field of microwave absorption materials and can also provide ideas for the design of layered structural absorbers.
基金National Key Technologies R&D Programof China (No.2007BAE41B01)
文摘The phenomenon of a material failure varies with its gauge length in use. In the present study, the breaking strengths of J30/C70 and J55/C45 blended yarns spun by the ring spinning technology were investigated with the employment of the equations derived from the Weibull theory. The four probability estimators of the Weibull distribution were also evaluated. The results showed that the estimator (2a) was acceptable for calculating the Weibull modulus of the jute/cotton blended yarns. With the exception of breaking strength of the J30/C70 at the gauge length of 200 ram, the breaking strengths of both blended yarn could be predicted accurately by the Eqs. (9) or (10) in this paper.
基金financially supported by the National Natural Science Foundation of China(Nos.51473081 and 51672143)Taishan Scholars Program,Outstanding Youth of Natural Science in Shandong Province(JQ201713)+1 种基金Natural Science Foundation of Shandong Province(ZR2017MEM018)ARC Discovery Project(No.170103317)
文摘Water splitting,as an advanced energy conversion technology,consists of two half reactions,including oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).However,the ideal electrocatalysts are noble metal based catalysts.Their high cost and scarcity in earth seriously restrict the large deployments.Ni Fe-based materials have attracted great attention in recent years due to their excellent catalytic properties for OER and HER.Nevertheless,their conductivity and electrochemical stability at high current density are unsatisfactory,resulting in ineffective water splitting due to high impedance and low stability.Recently,a series of catalysts coating Ni Fe-based materials on 3 D nickel foam were found to be extremely stable under the circumstance of high current density.In this review,we summarized the recent advances of NiFe-based materials on nickel foam for OER and HER,respectively,and further provided the perspectives for their future development.
基金Funded by the National Natural Science Foundation of China(No.51603134)the Graduate Program Construction Project Funding of Sichuan University(No.2017KCSJ036)+1 种基金the Opening Project of Key Laboratory of Leather Chemistry and Engeering(Sichuan University)Ministry of Education(SCU2021D005)。
文摘Waterborne elastic polyester (WEP) with different content of hard polyester was applied in the maize starch (MS) based composites (MS/WEP) via solution casting method.The effects of WEP with different contents of hard polyester on the structure and properties of starch were studied by Fourier transform infrared,X-ray diffraction,ultraviolet-visible,tensile test,differential scanning calorimeter,thermogravimetric analysis and moisture measurement.The experimental results show that the addition of WEP does not change the crystalline type of starch,and only reduces the crystallinity of starch.And the structure and properties of MS/WEP are related to not only the content of starch but also the microstructure of WEP or the content of hard polyester in WEP.Waterborne elastic polyester with 30wt% hard polyester (WEP30) has the best modification effect on the maize starch among all the WEPs.For example,MS/WEP30 film has the optimum toughness,aging resistance and transmittance,the lowest crystallinity and glass transition temperature among all the MS/WEP films,and the lower moisture content.It is related to the compatibility between starch and WEP,resulting from the number of physical crosslinking points in WEP..
文摘The effects of coagulation conditions on tensile properties of the regenerated cellulose fibers prepared by wet-spinning from NaOH/thiourea/urea(8∶6.5∶8 by weight)aqueous solvent were investigated by tensile tester,X-ray diffraction(XRD),and scanning electron microscope(SEM).The results show that the tensile properties of the as-spun fibers change with the coagualtion concentration,temperature,and time.When the spinning solution is coagulated in 10% H2SO4/12.5% Na2SO4 aqueous solution,the as-spun fibers have a typical structure of cellulose II,a circular cross-section,and homogeneous morphological structure.
文摘Cellulose pulps were directly dissolved in a green solvent of sodium hydrate/urea/thiourea/water with different composition for the purpose to prepare new regenerated cellulose fibers or films. The results showed that the highest solubility of cellulose in the solvent with the composition of 8/8/6.5/77.5. The results revealed that the pulp feeding sequence, stirring rate, pre-treatment of pulp and pulp size affected the cellulose concentration in the green solvent. Accordingly, the more effective dissolution method was proposed in order to get higher concentration of cellulose. Furthermore, the properties of solution prepared by different kinds of pulps in the solvent were investigated by ARES rheometer. Rheologieal analyses indicated that all cellulose aqueous solutions in their high concentration were pseudoplastic fluids and sensitive to temperature and tended to transform to gel when temperature increased.
基金Key Foundation of Shannxi Province,China (No.04JK181)China Textile Industry Association(No.2007049)
文摘A series of segmented polyether-polyester polyurethane with amorphous hydrophilic soft segment domains were prepared from 4,4'- diphenylmethane diisocyanate (MDI), polybutylene adipate (Glycol) 2000 (PBA2000), and polyethylene glycol 1000 (PEG1000), with 1,4-butanediol (BDO) as the chain extender. Furthermore, several representative properties of the polyurethanes, such as moisture permeability, water resistance, hydrophilic property, and phase inversion temperature, were investigated. The studies show that the structure and concentration of soft segment have a remarkable effect on the main application properties of polyurethane. On the contrary, the functional properties of the polyurethane are almost not affected by its hard segment.
基金New Century Excellent Talents of China ( NCET,No.040495)National Natural Science Foundation of China(NSFC, No.20474025)+1 种基金National Key Technology R&DProgram,China (No.2007BAE40B01)Innovative Research Team of Jiangnan University,China
文摘Without any preprocessing,polyester fabric has lower ability to hold on water and inks due to the smooth morphology of polyester fibers. Therefore, patterns directly printed with pigment inks have poor color yields and bleed easily. Pretreatments of polyester fabric were carried out with atmospheric air plasma under different experimental conditions. After plasma treatment the samples were printed with magenta pigment ink. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses indicated that the enhanced color performance was mainly contributed by not only the etching effect but also oxygen-containing polar groups induced onto fiber surfaces through plasma treatment. Thereby the surface modification of polyester fabrics using atmospheric-pressure air plasma offers a potential way to fabric pretreatment for pigment inkjet printing with the advantages of environmental friendly and energy saving over traditional pretreatment methods.
文摘The feasibility of combination process of jute degumming and bleaching with alkali-hydrogen peroxide in one-step-one-bath was discussed. The combination process basically has the similar function as the traditional two-step-two-bath method. The factors such as hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration, treatment time and temperature were studied respectively, and then an orthogonal experiment was designed to study the interactions among the hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration. After the designed experiments, the optimum treatment conditions were obtained as follows: hydrogen peroxide of 12g/L, sodium hydroxide of 4g/L, CBI of 4g/L, JFC of 1g/L, treatment time of 60min and temperature of 75℃.
基金Funded by Science and Technology Support Project of Sichuan Province(Nos.2014GZ0136 and 2015GZ0176)National Natural Science Foundation of China(No.51603134)
文摘A plasticizer triethylene glycol maleate(TEG-MA) was synthesized. The dominated monoester of moderate hydrophobicity with apparent oil-water partition coefficient of 0.042 in the product was confirmed by acid value determination, HPLC and FTIR. Its plasticizing effect on oxidized starch was manifested by crystallization, aging behaviour, moisture absorption, and mechanical performance. X-ray diffraction data showed that the relative crystallinity of the plasticized starch decreased. Both the crystal and the crystallinity of starch films were rarely changed in aging. Moisture absorption relied on the ester content and relative humidity. The elongation at break increased significantly with plasticizer content more than 10% in the matrix.
文摘Background:The few previous studies that focused on the effects of compression garments(CG)on distance running performance have simultaneously measured electromyogram,physiological,and perceptual parameters.Therefore,this study investigated the effects of CG on muscle activation and median frequency during and after distance running,as well as blood-lactate concentration and rating of perceived exertion(RPE)during distance running.Methods:Eight healthy male recreational runners were recruited to randomly perform two 40 min treadmill running trials,one with CG,and the other with control garment made of normal cloth.The RPE and the surface electromyography(EMG)of 5 lower extremity muscles including gluteus maximus(GM),rectus femoris(RF),semitendinosus(ST),tibialis anterior(TA),and gastrocnemius(GAS)were measured during the running trial.The blood-lactate levels before and after the running trial were measured.Results:Wearing CG led to significant lower muscle activation(p<0.05)in the GM(decreased 7.40%-14.31%),RF(decreased 4.39%-4.76%),and ST(decreased 3.42%-7.20%)muscles;moreover,significant higher median frequency(p<0.05)in the GM(increased 5.57%)and ST(increased 10.58%)muscles.Wearing CG did not alter the RPE values or the blood-lactate levels(p>0.05).Conclusion:Wearing CG was associated with significantly lower muscle activation and higher median frequency in the running-related key muscles during distance running.This finding suggested that wearing CG may improve muscle function,which might enhance running performance and prevent muscle fatigue.