Nickel molybdenum carbide catalysts were prepared and their activities in the CO2 reforming of methane at a low CO2/CH4 reactant ratio were investigated using a microreactor at atmospheric pressure and at 973 K.The ef...Nickel molybdenum carbide catalysts were prepared and their activities in the CO2 reforming of methane at a low CO2/CH4 reactant ratio were investigated using a microreactor at atmospheric pressure and at 973 K.The effect of the catalyst preparation method and the Ni/Mo ratio on the increase in catalyst life and the promotion of catalytic activity were investigated using N2 adsorption,X-ray diffraction, temperature-programmed carburization,temperature-programmed reaction,and a reforming reaction.The 25Ni75Mo catalyst that was carburized at 813 K exhibited the highest hydrogen formation ability and gave the least carbon deposition.The incomplete carburization of the Mo oxide species in the catalyst that was carburized at a lower temperature gradually gave a more active carburized species.The NiMoOxCy in the catalyst was more active in hydrogen formation during the dry reforming of methane whileβ-Mo2C andη-Mo3C2 were less active.展开更多
The vacuum electromagnetic induction nitriding technology was applied to prepare a gradient nitrided layer on the surface of a Ti6Al4V alloy,which possesses TiN andα-Ti(N)phases.Moreover,transmission electron microsc...The vacuum electromagnetic induction nitriding technology was applied to prepare a gradient nitrided layer on the surface of a Ti6Al4V alloy,which possesses TiN andα-Ti(N)phases.Moreover,transmission electron microscopy was conducted to confirm the presence of numerous high-density stacking faults caused by TiN and Ti_(2)N phases distributed on the surface of the alloy,along with a large number of basal stacking faults inside.A highdensity stacking fault led to serious distortion of lattice fringes.Lattice and numerous edge dislocations caused by defects were observed in the subsurface layer.For the surface layer,the Vickers hardness reached HV_(0.25)1211.30and the residual compressive stress increased,while the nano-hardness increased to 14.07 from 5.31 GPa in the substrate.The micrometre scratch test results indicated that the plasticity and hardness of the nitrided layer changed in a gradient.The 50-μm effective hardened layer depth and surface compressive stress of the Ti6Al4V alloy were enhanced by the stacking faults.展开更多
Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that ra...Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.展开更多
A block copolymer consisting of polyfluorene (PF) and polytriarylamine (PTAA) functionalized with green emitting phenoxazine moiety at the junction point of two blocks was designed and prepared for electroluminescent ...A block copolymer consisting of polyfluorene (PF) and polytriarylamine (PTAA) functionalized with green emitting phenoxazine moiety at the junction point of two blocks was designed and prepared for electroluminescent application. PF homopolymer was synthesized by Suzuki coupling polymerization, and was reacted with brominated phenoxazine. In the presence of the resulting PF functionalized with phenoxazine, C-N coupling polymerization of 4-(4’-bromophenyl)-4’’-butyldiphenylamine was carried out to afford a triblock copolymer, PTAA-phenoxazine-PF-phenoxazine-PTAA (PF-Ph-PTAA). Two types of random copolymers were also synthesized with fluorene and phenoxazine (PF2) by Suzuki coupling polymerization for comparison. All the polymers were soluble in common organic solvents and readily formed thin films by a solution processing. Prepared polymers exhibited similar UV absorption and PL emission in chloroform solutions. In a film state, the existence of phenoxazine unit drastically changed PL spectra. Although the content of phenoxazine unit in PF-Ph-PTAA was relatively high (13 mol%), it showed similar PL spectrum to that of PF2(phenoxazine content, 0.2 mol%) indicating that phenoxazine unit is isolated in single polymer chain nevertheless the high content. EL device based on PF-Ph-PTAA showed green-emission, suggesting that emission sites predominantly located in the vicinity of phenoxazine moiety because of its shallow HOMO level.展开更多
Hybrids consisting of a microporous film and polymeric microspheres were fabricated via a simple method without a special apparatus. Highly ordered microporous polymer films with honeycomb structure were fabricated by...Hybrids consisting of a microporous film and polymeric microspheres were fabricated via a simple method without a special apparatus. Highly ordered microporous polymer films with honeycomb structure were fabricated by a dissipative process utilizing amphiphilic poly(acrylic acid)- block-polystyrene, which was synthesized by atom transfer radical polymerization followed by an acid-catalyzed ester cleavage reaction. In order to embed the microsphere efficiently, the dried microporous films should be soaked in methanol to alter the surface functionality and to improve the wettability of the film surface. The introduction of amino functionality to polystyrene microspheres by seeded polymerization of N,N-dimethylaminoethyl methacrylate drastically improved the embedding efficiency. The effect of open pore size was also investigated.展开更多
Poly(4-butyltriarylamine)s with t-butyldimethylsilyl terminal protecting group (PBTPA-TBS) with various molecular weights were prepared by C-N coupling polymerization. The resulting precursors were postfunctionalized ...Poly(4-butyltriarylamine)s with t-butyldimethylsilyl terminal protecting group (PBTPA-TBS) with various molecular weights were prepared by C-N coupling polymerization. The resulting precursors were postfunctionalized and subse- quently used as macroinitiators for atom transfer radial polymerization (ATRP) of n-butyl acrylate (n-BA) and ethyl acrylate (EA). Both the polymerization processes were controlled and the polymers were characterized by 1H NMR, gel permeation chromatography (GPC) and thermal properties, which confirmed the successful synthesis of all the poly-mers. The microphase separated behaviors of the poly (4-butyltriarylamine)-block-poly (butyl acrylate) (PBTPA-b-PBA) were examined by AFM in the film showing phase separation structures for all the polymers. The photorefractive property of the composite based on PBTPA-b-PBA block copolymer was evaluated by two-beam coupling experiment. A relative high gain coefficient of 42.7 cm?1 was obtained at the electric field of 31 V/?m.展开更多
Micron-sized polymer particles from single poly(4-butyltriphenylamine) (PBTPA) homopolymer, binary polymer blend [PBTPA/poly(methyl methacrylate) (PMMA)], and ternary polymer blend (PBTPA/PBTPA-b-PMMA/PMMA) via a solv...Micron-sized polymer particles from single poly(4-butyltriphenylamine) (PBTPA) homopolymer, binary polymer blend [PBTPA/poly(methyl methacrylate) (PMMA)], and ternary polymer blend (PBTPA/PBTPA-b-PMMA/PMMA) via a solvent evaporation method, and the surface morphologies and inside structure of resulting particles were investigated. Spherical homopolymer particles with smooth surface were resulted from PBTPA with low molecular weight. In the case of binary blends (PBTPA/PMMA = 1/1), Janus (low molecular weight) and dumbbell (high molecular weight) type morphologies were observed. The particles based on ternary blends containing PBTPA-b-PMMA showed core-shell type morphologies (PMMA;core, PBTPA;shell). Degree of engulfment of PMMArich domain increased with the content of the block copolymer. The decrease of domain size was not observed although the block copolymer had a suitable structure as a compatibilizer for the blend. It was also found that the initial concentration of polymer solution had an effect on the final morphology.展开更多
A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enab...A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enables prediction with high accuracy but requires mesophyll variables.In addition,for practical use,it is desirable to have a technique that can predict A from easily available information.In this study,we propose a BLSTM augmented LSTM(BALSTM)model,which utilizes bi-directional LSTM(BLSTM)to indirectly reproduce the mesophyll variables required for LSTM.The most significant feature of the proposed model is that its hybrid architecture uses only three relatively easy-to-collect external environmental variables—photosynthetic photon flux density(Q_(in)),ambient CO_(2) concentration(C_(a)),and temperature(T_(air))—to generate mesophyll CO_(2) concentration(C_(i))and stomatal conductance to water vapor(g_(sw))as intermediate outputs.Then,A is predicted by applying the obtained intermediate outputs to the learning model.Accordingly,in this study,1)BALSTM(Q_(in),C_(a),T_(air))had a significantly higher A prediction accuracy than LSTM(Q_(in),C_(a),T_(air))in case of using only Q_(in),C_(a),and T_(air);2)BALSTMC_(i),g_(sw),which had C_(i) and g_(sw) as intermediate products,had the highest A prediction accuracy compared with other candidates;and 3)for samples where LSTM(Q_(in),C_(a),T_(air))had poor prediction accuracy,BALSTMC_(i),g_(sw)(Q_(in),C_(a),T_(air))clearly improved the results.However,it was found that incorrect predictions may be formed when certain factors are not reflected in the data(e.g.,timing,cultivar,and growth stage)or when the training data distribution that accounts for these factors differs from the predicted data distribution.Therefore,a robust model should be constructed in the future to improve the prediction accuracy of A by conducting gasexchange measurements(including a wide range of external environmental values)and by increasing the number of training data samples.展开更多
Thermotherapy and chemotherapy have received extensive attention to tumor treatment. However, thermal tolerance and drug resistance severely limit clinical effect of tumor therapy owing to endoplasmic reticulum(ER) st...Thermotherapy and chemotherapy have received extensive attention to tumor treatment. However, thermal tolerance and drug resistance severely limit clinical effect of tumor therapy owing to endoplasmic reticulum(ER) stress. Reducing thermal tolerance and drug resistance of tumors is an urgent challenge to be solved. In this work, we design a nanoplatform of PBA-Dtxl@MIL-101 as an ER inhibitor. Amino functionalized Fe-metal organic framework(MIL-101) nanoparticles are synthesized as p H and microwave(MW) dual stimuli-responsive drug delivery system. Then, the chemical chaperones of 4-phenylbutyric acid(PBA) and antineoplastic drug Docetaxel(Dtxl) were successfully loaded into MIL-101 nanoparticles to form PBA-Dtxl@MIL-101 nanoparticles. Furthermore, PBA-Dtxl@MIL-101 nanoparticles exhibit inhibitor effect of ER stress through upregulating caspase 9 proteins and reduce thermal tolerance by downregulating HSP 90. It was demonstrated that the therapy sensitized by PBA-Dtxl@MIL-101 nanoparticles obviously destroyed tumor cells, showing simultaneously enhanced thermo-chemo therapy.展开更多
This paper describes a wheeled underwater robot developed for locating chemical sources autonomously under stagnant flow conditions. In still water, the released chemical stays in the immediate vicinity of the source ...This paper describes a wheeled underwater robot developed for locating chemical sources autonomously under stagnant flow conditions. In still water, the released chemical stays in the immediate vicinity of the source location. The search for chemical sources under such conditions is extremely laborious since the presence of a chemical source cannot be detected from a distant place. The chemical sensors on the robot show no response unless a chemical substance released from the source arrives at the sensors. Crayfish in search of food are known to actively generate water currents by waving their small appendages with a fan-like shape. It is considered that the generated water currents help their olfactory search. The smell of food is carried to their olfactory organs from the surroundings by the generated flow, and then is perceived. The robot presented in this paper employs arms mimicking the maxillipeds of a crayfish to generate water currents and to draw chemicals to its sensors. By waving the arms vertically, a three-dimensional flow field is generated and water samples are drawn from a wide angular range. The direction of a chemical source can be determined by comparing the responses of four laterally aligned electrochemical sensors. Experimental results show that the flow field generated by the maxilliped arms is more effective in collecting chemical samples onto the sensors than that generated by a pump. The robot equipped with the maxilliped arms can detect the presence of a chemical source even if the source is placed off the trajectory of the robot.展开更多
Fifteen subspecies of the wood tiger moth, Arctia plantaginis (Lepidoptera: Erebidae: Arctiinae), have been recorded in the Northern Hemisphere. An analysis of crude pheromone extracts by GC equipped with an electroan...Fifteen subspecies of the wood tiger moth, Arctia plantaginis (Lepidoptera: Erebidae: Arctiinae), have been recorded in the Northern Hemisphere. An analysis of crude pheromone extracts by GC equipped with an electroantennographic (EAG) detector showed four EAG-active components (Comps. I–IV) that were commonly involved in the pheromone glands of two subspecies inhabiting Japan and Finland. Comp. I is a major component (>75%) and the others are minor components (3% - 15%). Their mass spectra, measured by GC/MS, revealed the chemical structures of C21 unsaturated hydrocarbons as follows: 3,6,9-triene for Comp. I, 4,6,9-triene for Comp. II, 1,3,6,9-tetraene for Comp. III, and 2,4,6,9-tetraene for Comp. IV. Comps. I and III are known Type II pheromone compounds, and their retention times coincide with those of the authentic standards with all Z configurations. As a next step, the extract was analyzed by GC/FT-IR to determine the configuration of Comps. II and IV. Their IR spectra showed two characteristic C-H bending absorptions around 990 and 945 cm-1 due to the conjugated dienyl moieties;thus, Z and E configurations were assigned to the double bonds at the 2- and 4-positions, respectively. Their Z double bonds at the 6- and 9-positions are indicated by no absorptions around 970 cm-1, due to the isolated double bonds with E configurations. Finally, the structures of Comps. II and IV were confirmed by synthesis using a double Wittig reaction. The synthetic (4E,6Z,9Z)-4,6,9-triene and (2Z,4E,6Z,9Z)-2,4,6,9-tetraene showed strong EAG activity, and their chemical data coincided well with those of the natural Comps. II and IV, indicating the correctness of the structure determination by GC/FT-IR analysis and its usefulness for Type II pheromone compounds.展开更多
Electroluminescent characteristics were investigated for the blue emitting devices fabricated with the blend systems consisting of hole transporting polytriarylamine (PTAA), electron transporting polyfluorene (PF), an...Electroluminescent characteristics were investigated for the blue emitting devices fabricated with the blend systems consisting of hole transporting polytriarylamine (PTAA), electron transporting polyfluorene (PF), and a block copolymer with both segments (PF-b-PTAA) as an active layer in order to elucidate the relationship between the chemical nature and morphology of the active layer, and EL performance. The addition of PF-b-PTAA to PF homopolymer afforded the hole injecting and/or electron blocking ability to increase the efficiency. The addition to PF/PTAA blend keeping the chemical composition constant also improved the performance by controlling the morphology and/or the domain size in phase-separated films.展开更多
Microspheres based on binary polymer blend consisting of polystyrene (PSt), poly (methyl methacrylate) (PMMA), block copolymer comprising PSt and PMMA subunits, and ternary polymer blend consisting of PSt, PMMA, and b...Microspheres based on binary polymer blend consisting of polystyrene (PSt), poly (methyl methacrylate) (PMMA), block copolymer comprising PSt and PMMA subunits, and ternary polymer blend consisting of PSt, PMMA, and block copolymer were fabricated by a solvent evaporation method, in which a polymer solution in dichloromethane was dispersed in water phase with the aid of a homogenizer to obtain an O/W emulsion followed by solvent evaporation with agitation to solidify the polymer. In the case of ternary blend, the effect of block copolymer content on the morphology of resulting spheres was investigated. Ternary blends afforded the bi-compartmental morphologies, the intermediate morphology between Janus and core-shell, which was confirmed by TEM observation. Seed polymerization of St or MMA was also carried out utilizing the resulting microspheres as seed particles in order to control the shape, and the surface morphology of particles. The particles with snowman-like morphology were obtained by seed polymerization of St using PSt/PMMA binary blend microspheres as seed particles. Surface roughness was controlled by the polymerization of MMA in the block copolymer seed, and that of St in the ternary blend seed.展开更多
Understanding aerosol-vegetation interactions is vital in ecosystems.However,the interactions remain elusive partly due to the lack of suitable plant growth chamber systems.Particularly,deposition of submicron particl...Understanding aerosol-vegetation interactions is vital in ecosystems.However,the interactions remain elusive partly due to the lack of suitable plant growth chamber systems.Particularly,deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles.In this work,we present a plant-growth chamber that was used to study the effect of sub-micron black carbon(BC)particles on the growth and photosynthesis of plants.The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them.Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition.The flow regime inside the chamber was numeri-cally calculated to predict the transportation of aerosol particles,suggesting the optimal operating conditions of the chamber.The gas-phase particle size distribution measurements showed that gener-ated BC particles were suspended in submicron diameter ranges.The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves.Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces.Using the developed chamber system,systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.展开更多
Hierarchically structured macro-mesoporous carbon catalysts were synthesized using dual templates of poly(methyl methacrylate)(PMMA)and Pluronic-123 to enhance cellulose saccharification.Characterizations conducted th...Hierarchically structured macro-mesoporous carbon catalysts were synthesized using dual templates of poly(methyl methacrylate)(PMMA)and Pluronic-123 to enhance cellulose saccharification.Characterizations conducted through scanning electron microscopy(SEM),X-ray diffraction(XRD),N2 adsorption-desorption isotherms,Fourier transform infrared(FT-IR)spectroscopy,and titration techniques confirmed high surface areas and specific pore size distributions,with macropores ranging from 78.3 to 251 nm and mesopores around 2.43-6.23 nm.An optimal PMMA-to-Tetraethyl orthosilicate(TEOS)ratio of 1:1.6 facilitated the highest cellulose conversion rate of 59.3%and a glucose yield of 22.1%.Notably,the medium-sized macropore catalyst,MMCS60-M,outperformed its purely mesoporous counterpart,with conversion rates and glucose yields of 80.8% and 45.5%,respectively.These results suggest the importance of a tailored pore architecture to enhance the accessibility of acid sites and facilitate effective mass transport,which is beneficial for optimizing saccharification processes.展开更多
In order to mimic hierarchical nanostructures in nature,particles of polymer blends consisting of poly(4-butyltriphenylamine)(PBTPA),poly(methyl methacrylate)(PMMA)and PBTPA-block-PMMA were fabricated by a solvent eva...In order to mimic hierarchical nanostructures in nature,particles of polymer blends consisting of poly(4-butyltriphenylamine)(PBTPA),poly(methyl methacrylate)(PMMA)and PBTPA-block-PMMA were fabricated by a solvent evaporation method.Effects of the molecular weight and the chemical composition of PBTPA-b-PMMA,molecular weights of homopolymers,and the composition of the blend on the morphology were investigated.The polymer blend particle consisting of PBTPA and PMMA homopolymers exhibited thermodynamically favored core-shell structure,in which more hydrophilic PMMA-shell surrounded PBTPA-core.The addition of 10 wt%of PBTPA-b-PMMA caused the morphological transition from core-shell toJanus or inversed core-shell,in which PBTPA-shell surrounded PMMA-core,depending on the molecular weight of PBTPA segment in PBTPA-b-PMMA.When the molecular weight of PMMA segment was higher than that of PMMA homopolymer,watermelon-like particles in which small PBTPA domain less than 80 nm dispersed in the PMMA domain surrounded by PBTPA shell were observed.As the ratio of PBTPA-b-PMMA increased,the interface of the macrophase separation became obscure.At 50 wt%of the PBTPA-b-PMMA,only microphase separation was observed.The measurement of interfacial tension by pendant drop method demonstrated that PBTPA-b-PMMA lower the interfacial tension between PBTPA and the aqueous phase to the value similar to that of PMMA with the aqueous phase.展开更多
In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was ...In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.展开更多
Current attempts in vaccine delivery systems concentrate on replicating the natural dissemination of live pathogens,but neglect that pathogens evolve to evade the immune system rather than to provoke it.In the case of...Current attempts in vaccine delivery systems concentrate on replicating the natural dissemination of live pathogens,but neglect that pathogens evolve to evade the immune system rather than to provoke it.In the case of enveloped RNA viruses,it is the natural dissemination of nucleocapsid protein(NP,core antigen)and surface antigen that delays NP exposure to immune surveillance.Here,we report a multi-layered aluminum hydroxide-stabilized emulsion(MASE)to dictate the delivery sequence of the antigens.In this manner,the receptor-binding domain(RBD,surface antigen)of the spike protein was trapped inside the nanocavity,while NP was absorbed on the outside of the droplets,enabling the burst release of NP before RBD.Compared with the natural packaging strategy,the inside-out strategy induced potent type I interferon-mediated innate immune responses and triggered an immune-potentiated environment in advance,which subsequently boosted CD40+DC activations and the engagement of the lymph nodes.In both H1N1 influenza and SARS-CoV-2 vaccines,rMASE significantly increased antigen-specific antibody secretion,memory T cell engagement,and Th1-biased immune response,which diminished viral loads after lethal challenge.By simply reversing the delivery sequence of the surface antigen and core antigen,the inside-out strategy may offer major implications for enhanced vaccinations against the enveloped RNA virus.展开更多
文摘Nickel molybdenum carbide catalysts were prepared and their activities in the CO2 reforming of methane at a low CO2/CH4 reactant ratio were investigated using a microreactor at atmospheric pressure and at 973 K.The effect of the catalyst preparation method and the Ni/Mo ratio on the increase in catalyst life and the promotion of catalytic activity were investigated using N2 adsorption,X-ray diffraction, temperature-programmed carburization,temperature-programmed reaction,and a reforming reaction.The 25Ni75Mo catalyst that was carburized at 813 K exhibited the highest hydrogen formation ability and gave the least carbon deposition.The incomplete carburization of the Mo oxide species in the catalyst that was carburized at a lower temperature gradually gave a more active carburized species.The NiMoOxCy in the catalyst was more active in hydrogen formation during the dry reforming of methane whileβ-Mo2C andη-Mo3C2 were less active.
基金financially supported by the Science and Technology Foundation of Guizhou Province(No.[2020]1Z041)。
文摘The vacuum electromagnetic induction nitriding technology was applied to prepare a gradient nitrided layer on the surface of a Ti6Al4V alloy,which possesses TiN andα-Ti(N)phases.Moreover,transmission electron microscopy was conducted to confirm the presence of numerous high-density stacking faults caused by TiN and Ti_(2)N phases distributed on the surface of the alloy,along with a large number of basal stacking faults inside.A highdensity stacking fault led to serious distortion of lattice fringes.Lattice and numerous edge dislocations caused by defects were observed in the subsurface layer.For the surface layer,the Vickers hardness reached HV_(0.25)1211.30and the residual compressive stress increased,while the nano-hardness increased to 14.07 from 5.31 GPa in the substrate.The micrometre scratch test results indicated that the plasticity and hardness of the nitrided layer changed in a gradient.The 50-μm effective hardened layer depth and surface compressive stress of the Ti6Al4V alloy were enhanced by the stacking faults.
文摘Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.
文摘A block copolymer consisting of polyfluorene (PF) and polytriarylamine (PTAA) functionalized with green emitting phenoxazine moiety at the junction point of two blocks was designed and prepared for electroluminescent application. PF homopolymer was synthesized by Suzuki coupling polymerization, and was reacted with brominated phenoxazine. In the presence of the resulting PF functionalized with phenoxazine, C-N coupling polymerization of 4-(4’-bromophenyl)-4’’-butyldiphenylamine was carried out to afford a triblock copolymer, PTAA-phenoxazine-PF-phenoxazine-PTAA (PF-Ph-PTAA). Two types of random copolymers were also synthesized with fluorene and phenoxazine (PF2) by Suzuki coupling polymerization for comparison. All the polymers were soluble in common organic solvents and readily formed thin films by a solution processing. Prepared polymers exhibited similar UV absorption and PL emission in chloroform solutions. In a film state, the existence of phenoxazine unit drastically changed PL spectra. Although the content of phenoxazine unit in PF-Ph-PTAA was relatively high (13 mol%), it showed similar PL spectrum to that of PF2(phenoxazine content, 0.2 mol%) indicating that phenoxazine unit is isolated in single polymer chain nevertheless the high content. EL device based on PF-Ph-PTAA showed green-emission, suggesting that emission sites predominantly located in the vicinity of phenoxazine moiety because of its shallow HOMO level.
文摘Hybrids consisting of a microporous film and polymeric microspheres were fabricated via a simple method without a special apparatus. Highly ordered microporous polymer films with honeycomb structure were fabricated by a dissipative process utilizing amphiphilic poly(acrylic acid)- block-polystyrene, which was synthesized by atom transfer radical polymerization followed by an acid-catalyzed ester cleavage reaction. In order to embed the microsphere efficiently, the dried microporous films should be soaked in methanol to alter the surface functionality and to improve the wettability of the film surface. The introduction of amino functionality to polystyrene microspheres by seeded polymerization of N,N-dimethylaminoethyl methacrylate drastically improved the embedding efficiency. The effect of open pore size was also investigated.
文摘Poly(4-butyltriarylamine)s with t-butyldimethylsilyl terminal protecting group (PBTPA-TBS) with various molecular weights were prepared by C-N coupling polymerization. The resulting precursors were postfunctionalized and subse- quently used as macroinitiators for atom transfer radial polymerization (ATRP) of n-butyl acrylate (n-BA) and ethyl acrylate (EA). Both the polymerization processes were controlled and the polymers were characterized by 1H NMR, gel permeation chromatography (GPC) and thermal properties, which confirmed the successful synthesis of all the poly-mers. The microphase separated behaviors of the poly (4-butyltriarylamine)-block-poly (butyl acrylate) (PBTPA-b-PBA) were examined by AFM in the film showing phase separation structures for all the polymers. The photorefractive property of the composite based on PBTPA-b-PBA block copolymer was evaluated by two-beam coupling experiment. A relative high gain coefficient of 42.7 cm?1 was obtained at the electric field of 31 V/?m.
文摘Micron-sized polymer particles from single poly(4-butyltriphenylamine) (PBTPA) homopolymer, binary polymer blend [PBTPA/poly(methyl methacrylate) (PMMA)], and ternary polymer blend (PBTPA/PBTPA-b-PMMA/PMMA) via a solvent evaporation method, and the surface morphologies and inside structure of resulting particles were investigated. Spherical homopolymer particles with smooth surface were resulted from PBTPA with low molecular weight. In the case of binary blends (PBTPA/PMMA = 1/1), Janus (low molecular weight) and dumbbell (high molecular weight) type morphologies were observed. The particles based on ternary blends containing PBTPA-b-PMMA showed core-shell type morphologies (PMMA;core, PBTPA;shell). Degree of engulfment of PMMArich domain increased with the content of the block copolymer. The decrease of domain size was not observed although the block copolymer had a suitable structure as a compatibilizer for the blend. It was also found that the initial concentration of polymer solution had an effect on the final morphology.
基金the support of JST PRESTO(Grant No.JPMJPR16O3)JSPS KAKENHI(Grant Nos.16KK0169 and 19K15944).
文摘A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enables prediction with high accuracy but requires mesophyll variables.In addition,for practical use,it is desirable to have a technique that can predict A from easily available information.In this study,we propose a BLSTM augmented LSTM(BALSTM)model,which utilizes bi-directional LSTM(BLSTM)to indirectly reproduce the mesophyll variables required for LSTM.The most significant feature of the proposed model is that its hybrid architecture uses only three relatively easy-to-collect external environmental variables—photosynthetic photon flux density(Q_(in)),ambient CO_(2) concentration(C_(a)),and temperature(T_(air))—to generate mesophyll CO_(2) concentration(C_(i))and stomatal conductance to water vapor(g_(sw))as intermediate outputs.Then,A is predicted by applying the obtained intermediate outputs to the learning model.Accordingly,in this study,1)BALSTM(Q_(in),C_(a),T_(air))had a significantly higher A prediction accuracy than LSTM(Q_(in),C_(a),T_(air))in case of using only Q_(in),C_(a),and T_(air);2)BALSTMC_(i),g_(sw),which had C_(i) and g_(sw) as intermediate products,had the highest A prediction accuracy compared with other candidates;and 3)for samples where LSTM(Q_(in),C_(a),T_(air))had poor prediction accuracy,BALSTMC_(i),g_(sw)(Q_(in),C_(a),T_(air))clearly improved the results.However,it was found that incorrect predictions may be formed when certain factors are not reflected in the data(e.g.,timing,cultivar,and growth stage)or when the training data distribution that accounts for these factors differs from the predicted data distribution.Therefore,a robust model should be constructed in the future to improve the prediction accuracy of A by conducting gasexchange measurements(including a wide range of external environmental values)and by increasing the number of training data samples.
基金financial support from the Beijing Natural Science Foundation (No. 2202057)Sichuan Science and Technology Program (No. 2020YFSY0018)。
文摘Thermotherapy and chemotherapy have received extensive attention to tumor treatment. However, thermal tolerance and drug resistance severely limit clinical effect of tumor therapy owing to endoplasmic reticulum(ER) stress. Reducing thermal tolerance and drug resistance of tumors is an urgent challenge to be solved. In this work, we design a nanoplatform of PBA-Dtxl@MIL-101 as an ER inhibitor. Amino functionalized Fe-metal organic framework(MIL-101) nanoparticles are synthesized as p H and microwave(MW) dual stimuli-responsive drug delivery system. Then, the chemical chaperones of 4-phenylbutyric acid(PBA) and antineoplastic drug Docetaxel(Dtxl) were successfully loaded into MIL-101 nanoparticles to form PBA-Dtxl@MIL-101 nanoparticles. Furthermore, PBA-Dtxl@MIL-101 nanoparticles exhibit inhibitor effect of ER stress through upregulating caspase 9 proteins and reduce thermal tolerance by downregulating HSP 90. It was demonstrated that the therapy sensitized by PBA-Dtxl@MIL-101 nanoparticles obviously destroyed tumor cells, showing simultaneously enhanced thermo-chemo therapy.
文摘This paper describes a wheeled underwater robot developed for locating chemical sources autonomously under stagnant flow conditions. In still water, the released chemical stays in the immediate vicinity of the source location. The search for chemical sources under such conditions is extremely laborious since the presence of a chemical source cannot be detected from a distant place. The chemical sensors on the robot show no response unless a chemical substance released from the source arrives at the sensors. Crayfish in search of food are known to actively generate water currents by waving their small appendages with a fan-like shape. It is considered that the generated water currents help their olfactory search. The smell of food is carried to their olfactory organs from the surroundings by the generated flow, and then is perceived. The robot presented in this paper employs arms mimicking the maxillipeds of a crayfish to generate water currents and to draw chemicals to its sensors. By waving the arms vertically, a three-dimensional flow field is generated and water samples are drawn from a wide angular range. The direction of a chemical source can be determined by comparing the responses of four laterally aligned electrochemical sensors. Experimental results show that the flow field generated by the maxilliped arms is more effective in collecting chemical samples onto the sensors than that generated by a pump. The robot equipped with the maxilliped arms can detect the presence of a chemical source even if the source is placed off the trajectory of the robot.
文摘Fifteen subspecies of the wood tiger moth, Arctia plantaginis (Lepidoptera: Erebidae: Arctiinae), have been recorded in the Northern Hemisphere. An analysis of crude pheromone extracts by GC equipped with an electroantennographic (EAG) detector showed four EAG-active components (Comps. I–IV) that were commonly involved in the pheromone glands of two subspecies inhabiting Japan and Finland. Comp. I is a major component (>75%) and the others are minor components (3% - 15%). Their mass spectra, measured by GC/MS, revealed the chemical structures of C21 unsaturated hydrocarbons as follows: 3,6,9-triene for Comp. I, 4,6,9-triene for Comp. II, 1,3,6,9-tetraene for Comp. III, and 2,4,6,9-tetraene for Comp. IV. Comps. I and III are known Type II pheromone compounds, and their retention times coincide with those of the authentic standards with all Z configurations. As a next step, the extract was analyzed by GC/FT-IR to determine the configuration of Comps. II and IV. Their IR spectra showed two characteristic C-H bending absorptions around 990 and 945 cm-1 due to the conjugated dienyl moieties;thus, Z and E configurations were assigned to the double bonds at the 2- and 4-positions, respectively. Their Z double bonds at the 6- and 9-positions are indicated by no absorptions around 970 cm-1, due to the isolated double bonds with E configurations. Finally, the structures of Comps. II and IV were confirmed by synthesis using a double Wittig reaction. The synthetic (4E,6Z,9Z)-4,6,9-triene and (2Z,4E,6Z,9Z)-2,4,6,9-tetraene showed strong EAG activity, and their chemical data coincided well with those of the natural Comps. II and IV, indicating the correctness of the structure determination by GC/FT-IR analysis and its usefulness for Type II pheromone compounds.
文摘Electroluminescent characteristics were investigated for the blue emitting devices fabricated with the blend systems consisting of hole transporting polytriarylamine (PTAA), electron transporting polyfluorene (PF), and a block copolymer with both segments (PF-b-PTAA) as an active layer in order to elucidate the relationship between the chemical nature and morphology of the active layer, and EL performance. The addition of PF-b-PTAA to PF homopolymer afforded the hole injecting and/or electron blocking ability to increase the efficiency. The addition to PF/PTAA blend keeping the chemical composition constant also improved the performance by controlling the morphology and/or the domain size in phase-separated films.
文摘Microspheres based on binary polymer blend consisting of polystyrene (PSt), poly (methyl methacrylate) (PMMA), block copolymer comprising PSt and PMMA subunits, and ternary polymer blend consisting of PSt, PMMA, and block copolymer were fabricated by a solvent evaporation method, in which a polymer solution in dichloromethane was dispersed in water phase with the aid of a homogenizer to obtain an O/W emulsion followed by solvent evaporation with agitation to solidify the polymer. In the case of ternary blend, the effect of block copolymer content on the morphology of resulting spheres was investigated. Ternary blends afforded the bi-compartmental morphologies, the intermediate morphology between Janus and core-shell, which was confirmed by TEM observation. Seed polymerization of St or MMA was also carried out utilizing the resulting microspheres as seed particles in order to control the shape, and the surface morphology of particles. The particles with snowman-like morphology were obtained by seed polymerization of St using PSt/PMMA binary blend microspheres as seed particles. Surface roughness was controlled by the polymerization of MMA in the block copolymer seed, and that of St in the ternary blend seed.
基金supported by Ministry of Education,Culture,Sports,Science,and Technology(MEXT)of Japan(Kakenhi Grant no.20120010,20120009,and 20120004)Japan Society for the Promotion of Science(JSPS)Kakenhi Grant(No.23560904,26420761,17K06903,18H02203 and 20K05188).
文摘Understanding aerosol-vegetation interactions is vital in ecosystems.However,the interactions remain elusive partly due to the lack of suitable plant growth chamber systems.Particularly,deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles.In this work,we present a plant-growth chamber that was used to study the effect of sub-micron black carbon(BC)particles on the growth and photosynthesis of plants.The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them.Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition.The flow regime inside the chamber was numeri-cally calculated to predict the transportation of aerosol particles,suggesting the optimal operating conditions of the chamber.The gas-phase particle size distribution measurements showed that gener-ated BC particles were suspended in submicron diameter ranges.The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves.Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces.Using the developed chamber system,systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.
文摘Hierarchically structured macro-mesoporous carbon catalysts were synthesized using dual templates of poly(methyl methacrylate)(PMMA)and Pluronic-123 to enhance cellulose saccharification.Characterizations conducted through scanning electron microscopy(SEM),X-ray diffraction(XRD),N2 adsorption-desorption isotherms,Fourier transform infrared(FT-IR)spectroscopy,and titration techniques confirmed high surface areas and specific pore size distributions,with macropores ranging from 78.3 to 251 nm and mesopores around 2.43-6.23 nm.An optimal PMMA-to-Tetraethyl orthosilicate(TEOS)ratio of 1:1.6 facilitated the highest cellulose conversion rate of 59.3%and a glucose yield of 22.1%.Notably,the medium-sized macropore catalyst,MMCS60-M,outperformed its purely mesoporous counterpart,with conversion rates and glucose yields of 80.8% and 45.5%,respectively.These results suggest the importance of a tailored pore architecture to enhance the accessibility of acid sites and facilitate effective mass transport,which is beneficial for optimizing saccharification processes.
基金supported by Institute of Global Innovation Research in Tokyo University of Agriculture and Technology(TUAT).
文摘In order to mimic hierarchical nanostructures in nature,particles of polymer blends consisting of poly(4-butyltriphenylamine)(PBTPA),poly(methyl methacrylate)(PMMA)and PBTPA-block-PMMA were fabricated by a solvent evaporation method.Effects of the molecular weight and the chemical composition of PBTPA-b-PMMA,molecular weights of homopolymers,and the composition of the blend on the morphology were investigated.The polymer blend particle consisting of PBTPA and PMMA homopolymers exhibited thermodynamically favored core-shell structure,in which more hydrophilic PMMA-shell surrounded PBTPA-core.The addition of 10 wt%of PBTPA-b-PMMA caused the morphological transition from core-shell toJanus or inversed core-shell,in which PBTPA-shell surrounded PMMA-core,depending on the molecular weight of PBTPA segment in PBTPA-b-PMMA.When the molecular weight of PMMA segment was higher than that of PMMA homopolymer,watermelon-like particles in which small PBTPA domain less than 80 nm dispersed in the PMMA domain surrounded by PBTPA shell were observed.As the ratio of PBTPA-b-PMMA increased,the interface of the macrophase separation became obscure.At 50 wt%of the PBTPA-b-PMMA,only microphase separation was observed.The measurement of interfacial tension by pendant drop method demonstrated that PBTPA-b-PMMA lower the interfacial tension between PBTPA and the aqueous phase to the value similar to that of PMMA with the aqueous phase.
基金This paper was supported by the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20191019)the Natural Science Research Project in Colleges and Universities in Jiangsu Province of China(Grant No.19KJB470022)+1 种基金the Scientific Research Start-up Foundation funding of High-level Introduction Talents of Nanjing Institute of Technology(Grant No.YKJ201912)the Open Fund Project of the Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education of Southeast University.
文摘In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.
基金supported by the National Key Research and Development Program of China(2021YFE020527,2021YFC2302605,2021YFC2300142),"From 0 to 1"Original Innovation Project of Basic Frontier Scientific Research Program of Chinese Academy of Sciences(ZDBS-LY-SLH040)Bejing Nova Program(Z201100006820139)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.21821005)+4 种基金CAS Project for Young Scientists in Basic Research(YSBR-010)the Pilot Project of Chinese Academy of Sciences(Grant No.XDB29040303)The National Natural Science Fund for Outstanding Young Scholar(T2222022)National Natural Science Foundation of China(Grant No.32030062),Youth Innovation Promotion Association of the Chinese Academy of Sciences(NO.2020000053)the foundation of Innovation Academy for Green Manufacture Institute,Chinese Academy of Sciences(Grand No.IAGM2020C30).
文摘Current attempts in vaccine delivery systems concentrate on replicating the natural dissemination of live pathogens,but neglect that pathogens evolve to evade the immune system rather than to provoke it.In the case of enveloped RNA viruses,it is the natural dissemination of nucleocapsid protein(NP,core antigen)and surface antigen that delays NP exposure to immune surveillance.Here,we report a multi-layered aluminum hydroxide-stabilized emulsion(MASE)to dictate the delivery sequence of the antigens.In this manner,the receptor-binding domain(RBD,surface antigen)of the spike protein was trapped inside the nanocavity,while NP was absorbed on the outside of the droplets,enabling the burst release of NP before RBD.Compared with the natural packaging strategy,the inside-out strategy induced potent type I interferon-mediated innate immune responses and triggered an immune-potentiated environment in advance,which subsequently boosted CD40+DC activations and the engagement of the lymph nodes.In both H1N1 influenza and SARS-CoV-2 vaccines,rMASE significantly increased antigen-specific antibody secretion,memory T cell engagement,and Th1-biased immune response,which diminished viral loads after lethal challenge.By simply reversing the delivery sequence of the surface antigen and core antigen,the inside-out strategy may offer major implications for enhanced vaccinations against the enveloped RNA virus.
