Objective and Impact Statement:The microspheres were widely utilized in the field of life sciences,and we have developed an innovative microelectromechanical system(MEMS)-based bioprinting technology(MBT)system for th...Objective and Impact Statement:The microspheres were widely utilized in the field of life sciences,and we have developed an innovative microelectromechanical system(MEMS)-based bioprinting technology(MBT)system for the preparation of the microspheres.The microspheres can be automatically and high-throughput produced with this cutting-edge system.Introduction and Methods:This paper mainly introduced a novel,efficient,and cost-effective approach for the microsphere fabrication with the MBT system.In this work,the whole microsphere production equipment was built and the optimal conditions(like concentration,drying temperature,frequency,and voltage)for generating uniform hydroxypropyl cellulose-cyclosporine A(HPC-CsA)and poly-l-lactic acid(PLLA)microspheres were explored.Results:Results demonstrated that the optimal uniformity of HPC-CsA microspheres was achieved at 2%(w/v)HPC-CsA mixture,45°C(drying temperature),1,000 Hz(frequency),and 25 V(voltage amplitude).CsA microspheres[coefficient of variation(CV):~9%]are successfully synthesized,and the drug encapsulation rate was 84.8%.The methodology was further used to produce PLLA microspheres with a diameter of~2.55μm,and the best CV value achieved 6.84%.Conclusion:This investigation fully highlighted the integration of MEMS and bioprinting as a promising tool for the microsphere fabrication,and this MBT system had huge potential applications in pharmaceutical formulations and medical aesthetics.展开更多
Secure control against cyber attacks becomes increasingly significant in cyber-physical systems(CPSs).False data injection attacks are a class of cyber attacks that aim to compromise CPS functions by injecting false d...Secure control against cyber attacks becomes increasingly significant in cyber-physical systems(CPSs).False data injection attacks are a class of cyber attacks that aim to compromise CPS functions by injecting false data such as sensor measurements and control signals.For quantified false data injection attacks,this paper establishes an effective defense framework from the energy conversion perspective.Then,we design an energy controller to dynamically adjust the system energy changes caused by unknown attacks.The designed energy controller stabilizes the attacked CPSs and ensures the dynamic performance of the system by adjusting the amount of damping injection.Moreover,with the disturbance attenuation technique,the burden of control system design is simplified because there is no need to design an attack observer.In addition,this secure control method is simple to implement because it avoids complicated mathematical operations.The effectiveness of our control method is demonstrated through an industrial CPS that controls a permanent magnet synchronous motor.展开更多
Nitrogen(N)and potassium(K)are the most required nutrients for corn and wheat production.Increasing the N application rate usually boosts crop yields.However,many uncertainties remain for K management.Potassium defici...Nitrogen(N)and potassium(K)are the most required nutrients for corn and wheat production.Increasing the N application rate usually boosts crop yields.However,many uncertainties remain for K management.Potassium deficiency results in yield losses,but K application rate based on the percentage of K+in the cation exchange capacity(CEC)is doubtful,especially in soil with high CEC.A field trial was conducted to examine the effects of KCl application before sowing corn and wheat,by raising the percentage of K+in CEC at pH 7.0(CECpH7.0)to approximately 2.5%,3.5%,and 4.5%,and adding N as a topdressing(75,150,and 225 kg ha-1 to corn and 40,80,and 120 kg ha-1 to wheat)on the nutrition and yield of corn and wheat under a continuous no-till system(30 years).Exchangeable K+content increased in the topsoil(0–20 cm depth)up to 7.2 mmolc dm-3 after K application at the highest rate,which,however,did not result in significant increases in nutrient uptake and yields for both corn and wheat.The N application rate positively affected the uptake and removal of all macronutrients by corn and wheat.Applying N as a topdressing increased yields of corn and wheat by up to 83%and 22%,respectively.Our results suggest that in the soil with a high CECpH7.0(162.1 mmolc dm-3),the recommendation for K application made by considering the percentage of K+in the CECpH7.0 may result in excessive application of K fertilizer to crops with high K-recycling potential grown under a continuous no-till system.展开更多
TiC-316 L metal matrix composites were successfully printed with an epoxy resin-absolute ethanol system by direct ink writing(DIW) process in this study.Microstructure and fracture morphology of the samples were obser...TiC-316 L metal matrix composites were successfully printed with an epoxy resin-absolute ethanol system by direct ink writing(DIW) process in this study.Microstructure and fracture morphology of the samples were observed by a scanning electron microscope(SEM).Also,the relative density,hardness and transverse rupture strength(TRS) of the sintered samples were tested.The results show that the samples prepared with a new epoxy resin-absolute ethanol system by the DIW process have high solid content of printing slurry,good surface roughness,high relative density and high strength.The solid content of the slurry suitable for DIW was 60 vol%,and the internal diameter of the nozzle was set to 0.4 mm,the printing speed was set to 30 mm·s^(-1),and the layer height was set to 0.36 mm.For the sample with 35 wt% TiC-316 L,the relative density,hardness and TRS of the sintered sample can reach 99.3%,HRA 79.5 and 1438 MPa,respectively.展开更多
Giant reed is a suitable pioneer plant for metal-contaminated soil phytoremediation,however,it is imperative to dispose the metal-contaminated biomass after harvesting.The liquefaction of metal-contaminated giant reed...Giant reed is a suitable pioneer plant for metal-contaminated soil phytoremediation,however,it is imperative to dispose the metal-contaminated biomass after harvesting.The liquefaction of metal-contaminated giant reed biomass in ethylene glycol system with sulfuric acid as catalyst for the precursors of polyurethane compounds was studied.The results show that giant reed biomass from metal-contaminated soil is potentially liquefied and significantly affected by solvent/solid ratio,liquefaction temperature and liquefaction time （P〈0.05）.The liquefaction rate of biomass in acidified ethylene glycol system can reach 85.2% with optimized conditions of 60 min,170 ℃,3% sulfuric acid and solvent/biomass ratio of 5：1.The hydroxyl value of liquefied products is of 481 mg KOH/g while reactive hydroxyl groups of them are abundant,which is promised as potential precursors for polyurethane compounds.The solvent liquefaction is a potential method to dispose the metal-contaminated biomass,however,the containing-metal liquefied products should be studied deeply in order to get the suitable precursors in future.展开更多
In this paper, a semilinear elliptic-parabolic PDE system which arises in a two dimensional groundwater flow problem is studied. Existence and uniqueness results are established via the L￣p - L￣q a priori estimates ...In this paper, a semilinear elliptic-parabolic PDE system which arises in a two dimensional groundwater flow problem is studied. Existence and uniqueness results are established via the L￣p - L￣q a priori estimates and the inverse function theorem.展开更多
Massive data from observations,experiments and simulations of dynamical models in scientific and engineering fields make it desirable for data-driven methods to extract basic laws of these models.We present a novel me...Massive data from observations,experiments and simulations of dynamical models in scientific and engineering fields make it desirable for data-driven methods to extract basic laws of these models.We present a novel method to identify such high dimensional stochastic dynamical systems that are perturbed by a non-Gaussianα-stable Lévy noise.More explicitly,firstly a machine learning framework to solve the sparse regression problem is established to grasp the drift terms through one of nonlocal Kramers–Moyal formulas.Then the jump measure and intensity of the noise are disposed by the relationship with statistical characteristics of the process.Three examples are then given to demonstrate the feasibility.This approach proposes an effective way to understand the complex phenomena of systems under non-Gaussian fluctuations and illuminates some insights into the exploration for further typical dynamical indicators such as the maximum likelihood transition path or mean exit time of these stochastic systems.展开更多
The antioxygenic activity of Solanum nigrum L. leaves and its various solvent extracts were evaluated using sunflower oil model system. Leaf powder and its methanol/water (80:20) soluble fraction showed strong antioxy...The antioxygenic activity of Solanum nigrum L. leaves and its various solvent extracts were evaluated using sunflower oil model system. Leaf powder and its methanol/water (80:20) soluble fraction showed strong antioxygenic activity in refined sunflower oil. On the other hand, ethyl acetate fraction exhibited marginal antioxygenic activity, whereas the water soluble fraction was practically devoid of any activity in refined sunflower oil. Thermal stability of different extracts of Solanum nigrum L. leaves heated at 80?C in refined sunflower oil also indicated the strong efficacy of methanol/water (80:20) extract to inhibit thermal oxidation. Solanum nigrum L. contain high levels of magnesium (239.0 mg/100g) and phosphorous (80.3 mg/100g). Fatty acid analysis of the lipid extracted from Solanum nigrum L. leaves indicated the presence of linoleic (59.1%) as a major fatty acid. The result of this study confirmed the presence of antioxygenic compounds in leaves, in particular its methanol/water (80:20) extracts showed great potential as a natural antioxidant to inhibit lipid peroxidation in foods.展开更多
Second language(L2)motivation has been a topic which receives intensive attention.However,the peer effect on L2 motivation is insufficiently researched,although it is considered a crucial factor which may significantl...Second language(L2)motivation has been a topic which receives intensive attention.However,the peer effect on L2 motivation is insufficiently researched,although it is considered a crucial factor which may significantly mediate learners’L2 motivation.Hence,the current study adopted Dörnyei’s L2 Motivational Self System(L2MSS)as a theoretical framework and investigated in which specific aspects peers might affect the learners’L2 motivation and whether such effect was long-lasting.The research was designed as a small-scale qualitative study which was located in a language-focused experimental class project in China.Ten participants were recruited and individual interviews were conducted.The results demonstrated that,first,peers could remarkably influence the L2 motivation possessed by the students in the experimental class since they tended to create a clearer ideal L2 self and a more powerful ought-to L2 self.Second,although they had both positive and negative views towards the curriculum,a motivated peer climate could alleviate the pressure caused by the curriculum and reinforce positive attitudes.Third,such peer effect was not long-lasting.Based on the research results,pedagogical implications were proposed in terms of establishing a positive peer group and adjusting the emphasis of the curriculum.展开更多
Guava(Psidium guajava L.),a plant belonging to the Myrtaceae family,holds significant medicinal and nutritional values.Leaves of the plant are described to be elliptical with a dark green color and are utilized in the...Guava(Psidium guajava L.),a plant belonging to the Myrtaceae family,holds significant medicinal and nutritional values.Leaves of the plant are described to be elliptical with a dark green color and are utilized in the treatment of gastrointestinal and respiratory issues along with increasing the platelet count in patients suffering from dengue.In this review paper,the nutritional composition and bioactive compounds of guava leaves,including proteins,vitamins,minerals,and polysaccharides,have been reviewed.The methods of extraction of bioactive compounds from guava leaves and their bioactivities,including antioxidant,anti-diabetic,and anti-cancer potential,have been explored.Further,encapsulation techniques for improving the transport of bioactive compounds and living cells into foods have been studied.The application of guava leaves in different food systems such as herbal tea,pork sausage,chocolates,jelly,meals for chickens,functional beverages,and as antibacterial agents in food preservatives has also been investigated.The findings of this review illustrated that the phytochemicals present in guava leaves showed excellent antimicrobial and antioxidant properties.Encapsulation appears to be a promising technique for improving the stability,bioavailability,and controlled release of bioactive chemicals extracted from guava leaves.Different methods for the encapsulation of bioactive compounds employed and applied in distinct food systems showed preservation of phytochemicals,improved bioactivities,and nutritional values.Overall,this review paper demonstrated how guava leaves,an abundant source of bioactive compounds,can be used as a multipurpose component to create functional foods,edible coatings,and active packaging to enhance the nutritional,antioxidant,and antimicrobial properties of various food systems that have qualities that promote health.展开更多
Intonation refers to the use of supra-segmental features to convey pragmatic meanings at the sentence level in a linguistically structured way.The difference in intonation between the native language and a foreign lan...Intonation refers to the use of supra-segmental features to convey pragmatic meanings at the sentence level in a linguistically structured way.The difference in intonation between the native language and a foreign language may influence second language learners’acquisition of intonation.The purpose of this study is to explore the similarities and differences at the level of phonological representation between English and Chinese intonation systems.This study investigated English and Chinese intonation systems,respectively,from both form and meaning under the Auto-Segmental Metrical framework by referring to previous studies and illustrating examples.The results showed that in terms of form,there were notable differences in the structural elements and their inventories between the intonation systems of English and Chinese.In terms of meaning,assertions were represented by different structural elements in English and Chinese intonation systems;the types of structural elements in English intonation possessed the capability to convey complex and subtle meanings,contrasting with the comparatively simpler nature of Chinese intonation.The results reveal that Chinese EFL learners demonstrate considerable difficulties in the production of the structural elements of English intonation and their combinations due to L1 intonation interference.展开更多
基金sponsored by Shanghai Pujiang Program(23PJ1423400)Shanghai Rising-Star Program(23QB1405100)National Key Research and Development Program of China(2019YFA0707004 and SQ2021YFF0700202).
文摘Objective and Impact Statement:The microspheres were widely utilized in the field of life sciences,and we have developed an innovative microelectromechanical system(MEMS)-based bioprinting technology(MBT)system for the preparation of the microspheres.The microspheres can be automatically and high-throughput produced with this cutting-edge system.Introduction and Methods:This paper mainly introduced a novel,efficient,and cost-effective approach for the microsphere fabrication with the MBT system.In this work,the whole microsphere production equipment was built and the optimal conditions(like concentration,drying temperature,frequency,and voltage)for generating uniform hydroxypropyl cellulose-cyclosporine A(HPC-CsA)and poly-l-lactic acid(PLLA)microspheres were explored.Results:Results demonstrated that the optimal uniformity of HPC-CsA microspheres was achieved at 2%(w/v)HPC-CsA mixture,45°C(drying temperature),1,000 Hz(frequency),and 25 V(voltage amplitude).CsA microspheres[coefficient of variation(CV):~9%]are successfully synthesized,and the drug encapsulation rate was 84.8%.The methodology was further used to produce PLLA microspheres with a diameter of~2.55μm,and the best CV value achieved 6.84%.Conclusion:This investigation fully highlighted the integration of MEMS and bioprinting as a promising tool for the microsphere fabrication,and this MBT system had huge potential applications in pharmaceutical formulations and medical aesthetics.
基金supported in part by the National Science Foundation of China(61873103,61433006)。
文摘Secure control against cyber attacks becomes increasingly significant in cyber-physical systems(CPSs).False data injection attacks are a class of cyber attacks that aim to compromise CPS functions by injecting false data such as sensor measurements and control signals.For quantified false data injection attacks,this paper establishes an effective defense framework from the energy conversion perspective.Then,we design an energy controller to dynamically adjust the system energy changes caused by unknown attacks.The designed energy controller stabilizes the attacked CPSs and ensures the dynamic performance of the system by adjusting the amount of damping injection.Moreover,with the disturbance attenuation technique,the burden of control system design is simplified because there is no need to design an attack observer.In addition,this secure control method is simple to implement because it avoids complicated mathematical operations.The effectiveness of our control method is demonstrated through an industrial CPS that controls a permanent magnet synchronous motor.
文摘Nitrogen(N)and potassium(K)are the most required nutrients for corn and wheat production.Increasing the N application rate usually boosts crop yields.However,many uncertainties remain for K management.Potassium deficiency results in yield losses,but K application rate based on the percentage of K+in the cation exchange capacity(CEC)is doubtful,especially in soil with high CEC.A field trial was conducted to examine the effects of KCl application before sowing corn and wheat,by raising the percentage of K+in CEC at pH 7.0(CECpH7.0)to approximately 2.5%,3.5%,and 4.5%,and adding N as a topdressing(75,150,and 225 kg ha-1 to corn and 40,80,and 120 kg ha-1 to wheat)on the nutrition and yield of corn and wheat under a continuous no-till system(30 years).Exchangeable K+content increased in the topsoil(0–20 cm depth)up to 7.2 mmolc dm-3 after K application at the highest rate,which,however,did not result in significant increases in nutrient uptake and yields for both corn and wheat.The N application rate positively affected the uptake and removal of all macronutrients by corn and wheat.Applying N as a topdressing increased yields of corn and wheat by up to 83%and 22%,respectively.Our results suggest that in the soil with a high CECpH7.0(162.1 mmolc dm-3),the recommendation for K application made by considering the percentage of K+in the CECpH7.0 may result in excessive application of K fertilizer to crops with high K-recycling potential grown under a continuous no-till system.
基金financially supported by Heyuan Science and Technology Project(No.HEKE 000781)the Science and Technology Projects of Guangdong Province(No.2016B090914001)Jihua Laboratory Project“Additive Manufacturing for Difficulty-to-Machine Materials”(No.X190061UZ190)。
文摘TiC-316 L metal matrix composites were successfully printed with an epoxy resin-absolute ethanol system by direct ink writing(DIW) process in this study.Microstructure and fracture morphology of the samples were observed by a scanning electron microscope(SEM).Also,the relative density,hardness and transverse rupture strength(TRS) of the sintered samples were tested.The results show that the samples prepared with a new epoxy resin-absolute ethanol system by the DIW process have high solid content of printing slurry,good surface roughness,high relative density and high strength.The solid content of the slurry suitable for DIW was 60 vol%,and the internal diameter of the nozzle was set to 0.4 mm,the printing speed was set to 30 mm·s^(-1),and the layer height was set to 0.36 mm.For the sample with 35 wt% TiC-316 L,the relative density,hardness and TRS of the sintered sample can reach 99.3%,HRA 79.5 and 1438 MPa,respectively.
基金Project(41271330)supported by the National Natural Science Foundation of ChinaProject(2012BAC09B04)supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of ChinaProject(2012FJ1010)supported by the Science and Technology Major Program of Hunan Province,China
文摘Giant reed is a suitable pioneer plant for metal-contaminated soil phytoremediation,however,it is imperative to dispose the metal-contaminated biomass after harvesting.The liquefaction of metal-contaminated giant reed biomass in ethylene glycol system with sulfuric acid as catalyst for the precursors of polyurethane compounds was studied.The results show that giant reed biomass from metal-contaminated soil is potentially liquefied and significantly affected by solvent/solid ratio,liquefaction temperature and liquefaction time （P〈0.05）.The liquefaction rate of biomass in acidified ethylene glycol system can reach 85.2% with optimized conditions of 60 min,170 ℃,3% sulfuric acid and solvent/biomass ratio of 5：1.The hydroxyl value of liquefied products is of 481 mg KOH/g while reactive hydroxyl groups of them are abundant,which is promised as potential precursors for polyurethane compounds.The solvent liquefaction is a potential method to dispose the metal-contaminated biomass,however,the containing-metal liquefied products should be studied deeply in order to get the suitable precursors in future.
文摘In this paper, a semilinear elliptic-parabolic PDE system which arises in a two dimensional groundwater flow problem is studied. Existence and uniqueness results are established via the L￣p - L￣q a priori estimates and the inverse function theorem.
基金the National Natural Science Foundation of China(Grant No.12172167)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Massive data from observations,experiments and simulations of dynamical models in scientific and engineering fields make it desirable for data-driven methods to extract basic laws of these models.We present a novel method to identify such high dimensional stochastic dynamical systems that are perturbed by a non-Gaussianα-stable Lévy noise.More explicitly,firstly a machine learning framework to solve the sparse regression problem is established to grasp the drift terms through one of nonlocal Kramers–Moyal formulas.Then the jump measure and intensity of the noise are disposed by the relationship with statistical characteristics of the process.Three examples are then given to demonstrate the feasibility.This approach proposes an effective way to understand the complex phenomena of systems under non-Gaussian fluctuations and illuminates some insights into the exploration for further typical dynamical indicators such as the maximum likelihood transition path or mean exit time of these stochastic systems.
文摘The antioxygenic activity of Solanum nigrum L. leaves and its various solvent extracts were evaluated using sunflower oil model system. Leaf powder and its methanol/water (80:20) soluble fraction showed strong antioxygenic activity in refined sunflower oil. On the other hand, ethyl acetate fraction exhibited marginal antioxygenic activity, whereas the water soluble fraction was practically devoid of any activity in refined sunflower oil. Thermal stability of different extracts of Solanum nigrum L. leaves heated at 80?C in refined sunflower oil also indicated the strong efficacy of methanol/water (80:20) extract to inhibit thermal oxidation. Solanum nigrum L. contain high levels of magnesium (239.0 mg/100g) and phosphorous (80.3 mg/100g). Fatty acid analysis of the lipid extracted from Solanum nigrum L. leaves indicated the presence of linoleic (59.1%) as a major fatty acid. The result of this study confirmed the presence of antioxygenic compounds in leaves, in particular its methanol/water (80:20) extracts showed great potential as a natural antioxidant to inhibit lipid peroxidation in foods.
文摘Second language(L2)motivation has been a topic which receives intensive attention.However,the peer effect on L2 motivation is insufficiently researched,although it is considered a crucial factor which may significantly mediate learners’L2 motivation.Hence,the current study adopted Dörnyei’s L2 Motivational Self System(L2MSS)as a theoretical framework and investigated in which specific aspects peers might affect the learners’L2 motivation and whether such effect was long-lasting.The research was designed as a small-scale qualitative study which was located in a language-focused experimental class project in China.Ten participants were recruited and individual interviews were conducted.The results demonstrated that,first,peers could remarkably influence the L2 motivation possessed by the students in the experimental class since they tended to create a clearer ideal L2 self and a more powerful ought-to L2 self.Second,although they had both positive and negative views towards the curriculum,a motivated peer climate could alleviate the pressure caused by the curriculum and reinforce positive attitudes.Third,such peer effect was not long-lasting.Based on the research results,pedagogical implications were proposed in terms of establishing a positive peer group and adjusting the emphasis of the curriculum.
文摘Guava(Psidium guajava L.),a plant belonging to the Myrtaceae family,holds significant medicinal and nutritional values.Leaves of the plant are described to be elliptical with a dark green color and are utilized in the treatment of gastrointestinal and respiratory issues along with increasing the platelet count in patients suffering from dengue.In this review paper,the nutritional composition and bioactive compounds of guava leaves,including proteins,vitamins,minerals,and polysaccharides,have been reviewed.The methods of extraction of bioactive compounds from guava leaves and their bioactivities,including antioxidant,anti-diabetic,and anti-cancer potential,have been explored.Further,encapsulation techniques for improving the transport of bioactive compounds and living cells into foods have been studied.The application of guava leaves in different food systems such as herbal tea,pork sausage,chocolates,jelly,meals for chickens,functional beverages,and as antibacterial agents in food preservatives has also been investigated.The findings of this review illustrated that the phytochemicals present in guava leaves showed excellent antimicrobial and antioxidant properties.Encapsulation appears to be a promising technique for improving the stability,bioavailability,and controlled release of bioactive chemicals extracted from guava leaves.Different methods for the encapsulation of bioactive compounds employed and applied in distinct food systems showed preservation of phytochemicals,improved bioactivities,and nutritional values.Overall,this review paper demonstrated how guava leaves,an abundant source of bioactive compounds,can be used as a multipurpose component to create functional foods,edible coatings,and active packaging to enhance the nutritional,antioxidant,and antimicrobial properties of various food systems that have qualities that promote health.
文摘Intonation refers to the use of supra-segmental features to convey pragmatic meanings at the sentence level in a linguistically structured way.The difference in intonation between the native language and a foreign language may influence second language learners’acquisition of intonation.The purpose of this study is to explore the similarities and differences at the level of phonological representation between English and Chinese intonation systems.This study investigated English and Chinese intonation systems,respectively,from both form and meaning under the Auto-Segmental Metrical framework by referring to previous studies and illustrating examples.The results showed that in terms of form,there were notable differences in the structural elements and their inventories between the intonation systems of English and Chinese.In terms of meaning,assertions were represented by different structural elements in English and Chinese intonation systems;the types of structural elements in English intonation possessed the capability to convey complex and subtle meanings,contrasting with the comparatively simpler nature of Chinese intonation.The results reveal that Chinese EFL learners demonstrate considerable difficulties in the production of the structural elements of English intonation and their combinations due to L1 intonation interference.
