The strong background radiation in high enthalpy hypersonic shock tunnels has posed severe challenges for measurement using luminescent coatings.We proposed a solution for reducing background radiation from time-resol...The strong background radiation in high enthalpy hypersonic shock tunnels has posed severe challenges for measurement using luminescent coatings.We proposed a solution for reducing background radiation from time-resolved temperature-sensitive paint(TSP)measurement in a hypersonic flow with Ma=6.5 and T_(0)=3525 K.The TSP was applied on an inlet ramp model,and the images were taken by a high-speed camera at 2 kHz under a modulated excitation.The strong background radiation led to a low signal-to-noise ratio and significant errors for the first half of the 130-ms test duration.Accordingly,three noise reduction methods were developed and evaluated based on temporal reconstruction,spatial reconstruction and robust principal component analysis(RPCA),respectively.The RPCA method showed the best performance that successfully recovered high-quality TSP data for a majority of test duration(t≥40 ms).展开更多
Hybrid-sterility-mediated reproductive isolation is pivotal for speciation,yet the underlying molecular mechanisms and environmental responses remain unclear.Here,we report a temperature-sensitive pollen killer-protec...Hybrid-sterility-mediated reproductive isolation is pivotal for speciation,yet the underlying molecular mechanisms and environmental responses remain unclear.Here,we report a temperature-sensitive pollen killer-protector system at a three-gene Sa locus for indica-japonica rice hybrid sterility.Genetic analyses identified SaFL^(+),a strong pollen protector from Sa-i(indica allele),and SaFL^(-),a weak japonica allele from Sa-j,which is exclusively functional under high temperatures.Protein interaction,ubiquitination,and degradation assays showed that SaF^(+)and SaM^(+)from Sa-i form a pollen-killer complex to bind and ubiquitinate the reactive oxygen species scavenger COX11 for degradation in mitochondria,causing male sterility of the Sa-j pollen.Protein affinity and competitive binding assays indicated that in the Sa-i pollen,SaFL^(+)binds SaM^(+)to disrupt the killer complex and restore fertility.However,the weak protector SaFL^(-)can bind SaM^(+)under high temperatures,sparing the Sa-j pollen from sterility.Synteny comparisons and haplotype analyses showed that the Sa locus originated in ancient wild rice and underwent divergence within the Oryza genus during expansion from tropical to temperate environments,which might have driven latitudinal adaptation and reproductive isolation in rice populations.Thus,Sa represents a temperature-sensitive reproductive-isolation system associated with domestication and environmental adaptation in rice.展开更多
Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism.However,under prolonged storage or high temperature stress,insulin tends to unfold and aggregate i...Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism.However,under prolonged storage or high temperature stress,insulin tends to unfold and aggregate into toxic amyloid fibrils,leading to loss of physiological function.Inspired by natural chaperones,a series of temperature-sensitive polycaprolactone-based micelles were designed to prevent insulin from deactivation.The micelles were fabricated through the self-assembly of amphiphilic copolymers of methoxy poly(ethylene glycol)-poly(4-diethylformamide caprolactone-co-caprolactone)(mPEG_(17)-P(DECL-co-CL)),which had a regular spherical morphology with particle sizes of about 100 nm.In addition,the lower critical solution temperature(LCST)of the micelles could be tuned to 9 and 29℃by changing the ratio of DECL to CL.Benefiting from the temperature-sensitivity of DECL segment,the binding ability of micelles to insulin could be modulated by changing the temperature.Above LCST,micelles effectively inhibited insulin aggregation and protected it from thermal inactivation due to the strong binding ability between the hydrophobic segment DECL and insulin.Below LCST,DECL segment returned to hydrophilic and bound weakly with insulin,leading to the release of insulin and assisting in its recovery of secondary structure.Thus,these temperature-sensitive micelles provided an effective strategy for insulin protection.展开更多
In the training studio of the School of Architecture and Engineering at Xizang Vocational Technical College,Lhasa,Gyatso,a senior artist specializing in Tibetan-style architectural decorative painting,bent over to dem...In the training studio of the School of Architecture and Engineering at Xizang Vocational Technical College,Lhasa,Gyatso,a senior artist specializing in Tibetan-style architectural decorative painting,bent over to demonstrate a student how to paint.His left hand steadied the painting board,while his right hand held a brush pen to present the Tibetan-style painting technique of"blurring"-dipping the brush lightly into the pigment,spreading it from dark to light on the paper.The eight-petaled lotus,a symbol of auspiciousness,gradually took shape,blossoming with layers of vitality.展开更多
A new series of cellulose-graft-poly（N-isopropylacrylamide） （cellulose-g-PNIPAM） copolymers were prepared by atom transfer radical polymerization （ATRP） of N-isopropylacrylamide monomers from a cellulose-based m...A new series of cellulose-graft-poly（N-isopropylacrylamide） （cellulose-g-PNIPAM） copolymers were prepared by atom transfer radical polymerization （ATRP） of N-isopropylacrylamide monomers from a cellulose-based macro-initiator, which was homogeneously synthesized in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimC1）. The composition of cellulose-g-PNIPAM copolymers could be adjusted by altering the feeding ratio and reaction time. The resultant copolymers with relatively high content of PNIPAM segments （molar substitution of PNIPAM ≥ 18.3） were soluble in water at room temperature. Aqueous solutions of cellulose-g-PNIPAM copolymers exhibited clear temperature-sensitive behavior, and their sol-to-gel phase transition properties were investigated by dynamic light scattering （DLS） and UV measurements. Compared with pure PNIPAM, the cellulose-g-PNIPAM copolymers possessed higher lower critical solution temperatures （LCST） in a range from 36.9 ℃ to 40.8 ℃, which are close to normal human body temperature, and could be tuned by adjusting the content of PNIPAM segments in copolymers. Spherical structure of cellulose-g-PNIPAM copolymers formed at temperatures above LCST and its morphology was observed by TEM and SEM. These novel cellulose-g-PNIPAM copolymers may be attractive substrates for some biomedical applications, such as drug release and tissue engineering.展开更多
Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as t...Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as the object. Through the analysis of actual spindle air cutting experimental data on Leaderway-V450 machine, it is found that the temperature-sensitive points used for modeling is volatility, and this volatility directly leads to large changes on the collinear degree among modeling independent variables. Thus, the forecasting accuracy of multivariate regression model is severely affected, and the forecasting robustness becomes poor too. To overcome this effect, a modeling method of establishing thermal error models by using single temperature variable under the jamming of temperature-sensitive points＇ volatility is put forward. According to the actual data of thermal error measured in different seasons, it is proved that the single temperature variable model can reduce the loss of fore- casting accuracy resulted from the volatility of tempera- ture-sensitive points, especially for the prediction of cross quarter data, the improvement of forecasting accuracy is about 5 μm or more. The purpose that improving the robustness of the thermal error models is realized, which can provide a reference for selecting the modelingindependent variable in the application of thermal error compensation of CNC machine tools.展开更多
To develop a smart free-standing surface enhanced Raman scattering(SERS) substrate,silver nanoparticles(AgNPs) embedded temperature-sensitive nanofibrous membrane was fabricated by electrospinning their aqueous soluti...To develop a smart free-standing surface enhanced Raman scattering(SERS) substrate,silver nanoparticles(AgNPs) embedded temperature-sensitive nanofibrous membrane was fabricated by electrospinning their aqueous solution containing the copolymer poly(N-isopropylacrylamide-co-Nhydroxymethylacrylamide),followed by heat treatment to form crosslinking structure within its constituent nanofibers.To avoid negative effect of the additive like stabilizer and the reactant like reductant on their SERS efficiency,the AgNPs were in-situ synthesized through reducing Ag^+ions dissolved in the polymer solution by ultraviolet irradiation.The prepared hybrid nanofibrous membrane with high stability in aqueous medium can reach its swelling or deswelling equilibrium state within 15 seconds with the medium temperature changing between 25℃and 50℃alternately.When it was used as a free-standing SERS substrate,10^-12 mol/L of 4-nitrothiophenol in aqueous solution can be detected at room temperature,and elevating detection temperature can further lower its low detection limit.Since its generated SERS signal has desirable reproducibility,it can be used as SERS substrate for quantitative analysis.Moreover,the hybrid membrane as SERS substrate is capable of real-time monitoring the reduction of 4-nitrothiophenol into 4-aminothiophenol catalyzed by its embedded AgNPs,and the detected intermediate indicates that the reaction proceeds via a condensation route.展开更多
The forecast of sterile alteration for the temperature-sensitive genic male sterile （TGMS） line in two-line hybrid rice seed production was traditionally based on screen temperature determined by weather station. Th...The forecast of sterile alteration for the temperature-sensitive genic male sterile （TGMS） line in two-line hybrid rice seed production was traditionally based on screen temperature determined by weather station. The article put forward a new approach based on plant temperature, which was more exact and direct than the traditional method. The result of the simulation of the self-seeded setting rate of a widely used TGMS line, Peiai64S, by several temperature parameters and durations, showed that the fertility was directly affected by the plant temperature at a height of 20 cm or the air temperature around it in three days duration. Using the stem temperature of three days at a height of 20 cm as the simulation parameter, the fertility of Peiai64S had the maximum, minimum and optimum temperatures as 22.8, 21.7 and 22.5℃, respectively, whereas 23.2, 21.5 and 21.8℃ when using the air temperature of three days around the height of 20 cm as the parameter. Such temperature indices can be used to conclude the sterile alteration of TGMS for safeguarding seed production of twoline hybrid rice. The article also established a statistic model to conclude plant temperature by water temperatures at inflow and outflow, and air temperature and cloudage from weather station.展开更多
A novel series of poly(N-isopropylacrylamide-co-hydroxyethyl methacrylate) (p(NIPAM-co-HEMA)) microgels were prepared through precipitation polymerization. Nuclear magnetic resonance (NMR), transmission electron micro...A novel series of poly(N-isopropylacrylamide-co-hydroxyethyl methacrylate) (p(NIPAM-co-HEMA)) microgels were prepared through precipitation polymerization. Nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV) and dynamic light scattering (DLS) were employed to characterize the microgels. The experimental results indicate that the prepared microgels with narrow distribution remain good temperature sensitivity after incorporation of functional-OH groups. In marked contrast to the general rule, incorporation of hydrophilic HEMA makes the volume-phase-transition temperature shift to the lower temperature due to the strong intermolecular H-bonding between amide and -OH groups, -OH and -OH groups.展开更多
A temperature-sensitive (ts) mutant of the CHO-K1 cell line, tsTM18, grows at 340C but not at 390C. Smu1 is the gene responsible for ts defects of tsTM18 cells. Previously, we found that the Smu1 ts defect altered the...A temperature-sensitive (ts) mutant of the CHO-K1 cell line, tsTM18, grows at 340C but not at 390C. Smu1 is the gene responsible for ts defects of tsTM18 cells. Previously, we found that the Smu1 ts defect altered the localization (as indicated by enlargement of speckles) of SRSF1 (SF2/ASF) in tsTM18 cells cultured at 390C, suggesting a functional association between Smu1 and SRSF1. Speckles are subnuclear structures that may function as storage/assembly/ modification compartments to supply splicing factors to active transcription sites. The effect of the ts defect of Smu1 on the localization of other factors related to splicing has not been characterized yet. The mechanisms underlying the enlargement of speckles of SRSF1 remain unclear. In the present study, we found that the ts defect of Smu1 affected the nuclear localization of a splicing factor, SRSF2 (SC35), and factors involved in the exon-exon junction complex, Y14 and ALY. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the ts defect of Smu1 affected alternative splicing of endogenous Clk1/ Sty and SRSF2 genes. Mammalian Clk family kinases are shown to phosphorylate serine/arginine (SR) proteins in vitro and SRSF1 in vivo. RT-PCR analysis of Clk1/Sty showed an accumulation of the truncated form lacking kinase activity in tsTM18 cells incubated at 39?C. These data indicate that an accumulation of kinase-negative Clk1/Sty may lead to alteration of the localization of factors related to splicing resulting in the enlargement of speckles.展开更多
Silk has been widely used in the clothing industry due to their soft and smooth features,good biocompatibility,good heat dissipation,warmth and ultraviolet resistance.The application of fragrance to silk can significa...Silk has been widely used in the clothing industry due to their soft and smooth features,good biocompatibility,good heat dissipation,warmth and ultraviolet resistance.The application of fragrance to silk can significantly improve the performance of silk.However,there are two key scientific problems that need to be solved:slowing down the release rate of fragrances and increasing the scent lasting time of silk.In this study,cationic and temperature-sensitive liposomes were designed and prepared to encapsulate eugenol.These fragrance-loaded liposomes significantly slowed down the release rate of the fragrance and controlled the release rate of the fragrance in a thermo-sensitive manner.The liposomes adhered to the silk through electrostatic adsorption interaction.The positive charge on the fragranceloaded liposomes neutralized much negative charge on silk and thereby increasing the adhesion efficiency.展开更多
A kind of novel copolymer hydrogel of poly（N, N-dimethylaminoethyl methacrylate-co-N-isopropylacrylamide） （poly[DMAEMA/NIPAAm]） was synthesized by the initiation of K2S2O8, N, N＇-methylene-bis（acrylamide） （Bis...A kind of novel copolymer hydrogel of poly（N, N-dimethylaminoethyl methacrylate-co-N-isopropylacrylamide） （poly[DMAEMA/NIPAAm]） was synthesized by the initiation of K2S2O8, N, N＇-methylene-bis（acrylamide） （Bis） was used as the crosslinker. The effects of monomer content, pH and temperature on swelling ratio of the hydrogel were investigated; the thermo-sensitivity in deionized water and in physiological saline was determined. It showed that the swelling ratio of the hydrogel could be changed by changing the temperature or pH alternately. Both swelling ratio and LCST （Lower Critical Solution Temperature） of the hydrogel decreased with the increase of NIPAAm in the co-polymer content.展开更多
The swelling behavior of a temperature-sensitive poly-N-isopropylacrylamide(PNIPAM) hydrogel circular cylinder is studied subjected to combined extension-torsion and varied temperature. In this regard, a semi-analytic...The swelling behavior of a temperature-sensitive poly-N-isopropylacrylamide(PNIPAM) hydrogel circular cylinder is studied subjected to combined extension-torsion and varied temperature. In this regard, a semi-analytical solution is proposed for general combined loading. A finite element(FE) analysis is conducted, subjecting a hydrogel cylinder to the combined extension-torsion and the varied temperature to evaluate the validity and accuracy of the solution. A user-defined UHYPER subroutine is developed and verified under free and constrained swelling conditions. The FE results illustrate excellent agreement with the semi-analytical solution. Due to the complexity of the problem, some compositions and applied loading factors are analyzed. It is revealed that for larger cross-linked density and larger ending temperature, the cylinder yields higher stresses and smaller radial swelling deformation. Besides, the radial and hoop stresses increase by applying larger twist and axial stretch. The hoop stresses intersect at approximately R/Rout = 0.58, where the hoop stress vanishes. Besides, the axial force has direct and inverse relationships with the axial stretch and the twist, respectively. However, the resultant torsional moment behavior is complex, and the position of the maximum point varies significantly by altering the axial stretch and the twist.展开更多
William Somerset Maugham was one of the most popular British writers of his era.Many of his works are closely related to China,among which is the famous novel The Painted Veil.This novel narrates the love story betwee...William Somerset Maugham was one of the most popular British writers of his era.Many of his works are closely related to China,among which is the famous novel The Painted Veil.This novel narrates the love story between the heroine Kitty,an attractive but vainglorious middle-class lady,and the intelligent bacteriologist Walter Fane.This thesis aims at exploring the hetero image of China in The Painted Veil from the perspective of imagology.It comprises four chapters.Chapter one introduces the definition of the terms“Image”and“hetero image”.Chapter two analyzes Maugham’s diversified concepts of China:one is the positive and good image,and the other is the negative image.Chapter three illustrates the specific images of China revealed in the novel The Painted Veil,on both positive and negative aspects.After the exploration of the image of China from the perspective of imagology,we can sum up that actually,the image of China in Maugham’s eyes indicated in The Painted Veil is not the real China.It is a combination of the real world observed by Maugham and the imaginative world conceived by him influenced by his own specific culture and society.展开更多
At first glance,Lhapa Tsering appears modestly dressed,A:almost unassumingyet an artistic air surrounds him.A man of few words,his eyes light up with unmistakable passion the moment painting enters the conversation.Hi...At first glance,Lhapa Tsering appears modestly dressed,A:almost unassumingyet an artistic air surrounds him.A man of few words,his eyes light up with unmistakable passion the moment painting enters the conversation.His fingers lightly graze the paintbrush.展开更多
Through the analysis of the actual situation and process of painting industrial steel components in Hechang Company,we have modified the mixing ratio of paint,thinner,and curing agent.Additionally,we have effectively ...Through the analysis of the actual situation and process of painting industrial steel components in Hechang Company,we have modified the mixing ratio of paint,thinner,and curing agent.Additionally,we have effectively adjusted the drying time of various paint types under different seasons and temperatures.Eventually,a painting solution suitable for our company has been developed.According to this process,the painting quality has been significantly improved,costs have been saved,the labor intensity has been reduced,and production efficiency has been remarkably enhanced.展开更多
Fluorogen-activating proteins(FAPs)selectively bind to specific fluorophores,inducing fluorescence activation through the inhibition of torsion of fluorophores.This binding-activation mechanism provides a highly speci...Fluorogen-activating proteins(FAPs)selectively bind to specific fluorophores,inducing fluorescence activation through the inhibition of torsion of fluorophores.This binding-activation mechanism provides a highly specific and efficient fluorescence system that minimizes background signals,significantly enhancing the signal-to-noise ratio(SNR)and making it a powerful tool in live-cell imaging.The principle of binding-activation fluorescence is fundamental to point accumulation for imaging in nanoscale topography(PAINT)super-resolution imaging.However,the high binding affinity between traditional FAPfluorophore pairs limits their application in PAINT,thus hindering the rapid and dynamic imaging necessary for high-resolution cellular studies.In this work,we designed malachite green(MG)derivatives with bulky N-substituents to modulate the binding affinity of the MG-d L5^(**)fluorophore-FAP pair.This modification introduces steric hindrance in MG-dL5^(**)system,resulting in reduced binding affinity and practicability for fast,high-resolution PAINT imaging.Among the synthesized derivatives,MG-Pen showed optimal properties,enabling rapid and high-resolution PAINT imaging of dL5^(**)in living cells.This study highlights the potential of MG derivatives optimization in overcoming the limitations of fluorophore-FAP pairs for super-resolution imaging and provides a new approach for enhancing the performance of PAINT in living cell applications.展开更多
基金supported by the National Natural Science Foundation of China(Grants 11725209 and 11872038)and funding from Gas Turbine Research Institute of Shanghai Jiao Tong University.
文摘The strong background radiation in high enthalpy hypersonic shock tunnels has posed severe challenges for measurement using luminescent coatings.We proposed a solution for reducing background radiation from time-resolved temperature-sensitive paint(TSP)measurement in a hypersonic flow with Ma=6.5 and T_(0)=3525 K.The TSP was applied on an inlet ramp model,and the images were taken by a high-speed camera at 2 kHz under a modulated excitation.The strong background radiation led to a low signal-to-noise ratio and significant errors for the first half of the 130-ms test duration.Accordingly,three noise reduction methods were developed and evaluated based on temporal reconstruction,spatial reconstruction and robust principal component analysis(RPCA),respectively.The RPCA method showed the best performance that successfully recovered high-quality TSP data for a majority of test duration(t≥40 ms).
基金supported by the National Natural Science Foundation of China(32030080 to L.C.and 31991222 to Y.-G.L.)the Open Competition Program of the Top Ten Critical Priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(2022SDZG05 to L.C.)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(2022A1515110431 to G.L.and 2019B030302006 to Y.-G.L.)the Invigorate the Seed Industry of Guangdong Province(2024-NPY-00-044 to L.C.).
文摘Hybrid-sterility-mediated reproductive isolation is pivotal for speciation,yet the underlying molecular mechanisms and environmental responses remain unclear.Here,we report a temperature-sensitive pollen killer-protector system at a three-gene Sa locus for indica-japonica rice hybrid sterility.Genetic analyses identified SaFL^(+),a strong pollen protector from Sa-i(indica allele),and SaFL^(-),a weak japonica allele from Sa-j,which is exclusively functional under high temperatures.Protein interaction,ubiquitination,and degradation assays showed that SaF^(+)and SaM^(+)from Sa-i form a pollen-killer complex to bind and ubiquitinate the reactive oxygen species scavenger COX11 for degradation in mitochondria,causing male sterility of the Sa-j pollen.Protein affinity and competitive binding assays indicated that in the Sa-i pollen,SaFL^(+)binds SaM^(+)to disrupt the killer complex and restore fertility.However,the weak protector SaFL^(-)can bind SaM^(+)under high temperatures,sparing the Sa-j pollen from sterility.Synteny comparisons and haplotype analyses showed that the Sa locus originated in ancient wild rice and underwent divergence within the Oryza genus during expansion from tropical to temperate environments,which might have driven latitudinal adaptation and reproductive isolation in rice populations.Thus,Sa represents a temperature-sensitive reproductive-isolation system associated with domestication and environmental adaptation in rice.
基金financially supported by the National Natural Science Foundation of China(Nos.52273009 and 21674037).
文摘Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism.However,under prolonged storage or high temperature stress,insulin tends to unfold and aggregate into toxic amyloid fibrils,leading to loss of physiological function.Inspired by natural chaperones,a series of temperature-sensitive polycaprolactone-based micelles were designed to prevent insulin from deactivation.The micelles were fabricated through the self-assembly of amphiphilic copolymers of methoxy poly(ethylene glycol)-poly(4-diethylformamide caprolactone-co-caprolactone)(mPEG_(17)-P(DECL-co-CL)),which had a regular spherical morphology with particle sizes of about 100 nm.In addition,the lower critical solution temperature(LCST)of the micelles could be tuned to 9 and 29℃by changing the ratio of DECL to CL.Benefiting from the temperature-sensitivity of DECL segment,the binding ability of micelles to insulin could be modulated by changing the temperature.Above LCST,micelles effectively inhibited insulin aggregation and protected it from thermal inactivation due to the strong binding ability between the hydrophobic segment DECL and insulin.Below LCST,DECL segment returned to hydrophilic and bound weakly with insulin,leading to the release of insulin and assisting in its recovery of secondary structure.Thus,these temperature-sensitive micelles provided an effective strategy for insulin protection.
文摘In the training studio of the School of Architecture and Engineering at Xizang Vocational Technical College,Lhasa,Gyatso,a senior artist specializing in Tibetan-style architectural decorative painting,bent over to demonstrate a student how to paint.His left hand steadied the painting board,while his right hand held a brush pen to present the Tibetan-style painting technique of"blurring"-dipping the brush lightly into the pigment,spreading it from dark to light on the paper.The eight-petaled lotus,a symbol of auspiciousness,gradually took shape,blossoming with layers of vitality.
基金financially supported by the National Natural Science Foundation of China(No.51425307)
文摘A new series of cellulose-graft-poly（N-isopropylacrylamide） （cellulose-g-PNIPAM） copolymers were prepared by atom transfer radical polymerization （ATRP） of N-isopropylacrylamide monomers from a cellulose-based macro-initiator, which was homogeneously synthesized in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimC1）. The composition of cellulose-g-PNIPAM copolymers could be adjusted by altering the feeding ratio and reaction time. The resultant copolymers with relatively high content of PNIPAM segments （molar substitution of PNIPAM ≥ 18.3） were soluble in water at room temperature. Aqueous solutions of cellulose-g-PNIPAM copolymers exhibited clear temperature-sensitive behavior, and their sol-to-gel phase transition properties were investigated by dynamic light scattering （DLS） and UV measurements. Compared with pure PNIPAM, the cellulose-g-PNIPAM copolymers possessed higher lower critical solution temperatures （LCST） in a range from 36.9 ℃ to 40.8 ℃, which are close to normal human body temperature, and could be tuned by adjusting the content of PNIPAM segments in copolymers. Spherical structure of cellulose-g-PNIPAM copolymers formed at temperatures above LCST and its morphology was observed by TEM and SEM. These novel cellulose-g-PNIPAM copolymers may be attractive substrates for some biomedical applications, such as drug release and tissue engineering.
基金Supported by Key Project of National Natural Science Fund of China(Grant No.51490660/51490661)National Natural Science Foundation of China(Grant No.51175142)
文摘Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as the object. Through the analysis of actual spindle air cutting experimental data on Leaderway-V450 machine, it is found that the temperature-sensitive points used for modeling is volatility, and this volatility directly leads to large changes on the collinear degree among modeling independent variables. Thus, the forecasting accuracy of multivariate regression model is severely affected, and the forecasting robustness becomes poor too. To overcome this effect, a modeling method of establishing thermal error models by using single temperature variable under the jamming of temperature-sensitive points＇ volatility is put forward. According to the actual data of thermal error measured in different seasons, it is proved that the single temperature variable model can reduce the loss of fore- casting accuracy resulted from the volatility of tempera- ture-sensitive points, especially for the prediction of cross quarter data, the improvement of forecasting accuracy is about 5 μm or more. The purpose that improving the robustness of the thermal error models is realized, which can provide a reference for selecting the modelingindependent variable in the application of thermal error compensation of CNC machine tools.
基金the National Natural Science Foundation of China(Nos.51503033,51373030)
文摘To develop a smart free-standing surface enhanced Raman scattering(SERS) substrate,silver nanoparticles(AgNPs) embedded temperature-sensitive nanofibrous membrane was fabricated by electrospinning their aqueous solution containing the copolymer poly(N-isopropylacrylamide-co-Nhydroxymethylacrylamide),followed by heat treatment to form crosslinking structure within its constituent nanofibers.To avoid negative effect of the additive like stabilizer and the reactant like reductant on their SERS efficiency,the AgNPs were in-situ synthesized through reducing Ag^+ions dissolved in the polymer solution by ultraviolet irradiation.The prepared hybrid nanofibrous membrane with high stability in aqueous medium can reach its swelling or deswelling equilibrium state within 15 seconds with the medium temperature changing between 25℃and 50℃alternately.When it was used as a free-standing SERS substrate,10^-12 mol/L of 4-nitrothiophenol in aqueous solution can be detected at room temperature,and elevating detection temperature can further lower its low detection limit.Since its generated SERS signal has desirable reproducibility,it can be used as SERS substrate for quantitative analysis.Moreover,the hybrid membrane as SERS substrate is capable of real-time monitoring the reduction of 4-nitrothiophenol into 4-aminothiophenol catalyzed by its embedded AgNPs,and the detected intermediate indicates that the reaction proceeds via a condensation route.
文摘The forecast of sterile alteration for the temperature-sensitive genic male sterile （TGMS） line in two-line hybrid rice seed production was traditionally based on screen temperature determined by weather station. The article put forward a new approach based on plant temperature, which was more exact and direct than the traditional method. The result of the simulation of the self-seeded setting rate of a widely used TGMS line, Peiai64S, by several temperature parameters and durations, showed that the fertility was directly affected by the plant temperature at a height of 20 cm or the air temperature around it in three days duration. Using the stem temperature of three days at a height of 20 cm as the simulation parameter, the fertility of Peiai64S had the maximum, minimum and optimum temperatures as 22.8, 21.7 and 22.5℃, respectively, whereas 23.2, 21.5 and 21.8℃ when using the air temperature of three days around the height of 20 cm as the parameter. Such temperature indices can be used to conclude the sterile alteration of TGMS for safeguarding seed production of twoline hybrid rice. The article also established a statistic model to conclude plant temperature by water temperatures at inflow and outflow, and air temperature and cloudage from weather station.
文摘A novel series of poly(N-isopropylacrylamide-co-hydroxyethyl methacrylate) (p(NIPAM-co-HEMA)) microgels were prepared through precipitation polymerization. Nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV) and dynamic light scattering (DLS) were employed to characterize the microgels. The experimental results indicate that the prepared microgels with narrow distribution remain good temperature sensitivity after incorporation of functional-OH groups. In marked contrast to the general rule, incorporation of hydrophilic HEMA makes the volume-phase-transition temperature shift to the lower temperature due to the strong intermolecular H-bonding between amide and -OH groups, -OH and -OH groups.
文摘A temperature-sensitive (ts) mutant of the CHO-K1 cell line, tsTM18, grows at 340C but not at 390C. Smu1 is the gene responsible for ts defects of tsTM18 cells. Previously, we found that the Smu1 ts defect altered the localization (as indicated by enlargement of speckles) of SRSF1 (SF2/ASF) in tsTM18 cells cultured at 390C, suggesting a functional association between Smu1 and SRSF1. Speckles are subnuclear structures that may function as storage/assembly/ modification compartments to supply splicing factors to active transcription sites. The effect of the ts defect of Smu1 on the localization of other factors related to splicing has not been characterized yet. The mechanisms underlying the enlargement of speckles of SRSF1 remain unclear. In the present study, we found that the ts defect of Smu1 affected the nuclear localization of a splicing factor, SRSF2 (SC35), and factors involved in the exon-exon junction complex, Y14 and ALY. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the ts defect of Smu1 affected alternative splicing of endogenous Clk1/ Sty and SRSF2 genes. Mammalian Clk family kinases are shown to phosphorylate serine/arginine (SR) proteins in vitro and SRSF1 in vivo. RT-PCR analysis of Clk1/Sty showed an accumulation of the truncated form lacking kinase activity in tsTM18 cells incubated at 39?C. These data indicate that an accumulation of kinase-negative Clk1/Sty may lead to alteration of the localization of factors related to splicing resulting in the enlargement of speckles.
基金the National High Technology Research and Development Program(No.2016YFA0200303)the Beijing Natural Science Foundation(Nos.L172046,2192057)the National Natural Science Foundation of China(Nos.31771095,21875254 and 51573188)。
文摘Silk has been widely used in the clothing industry due to their soft and smooth features,good biocompatibility,good heat dissipation,warmth and ultraviolet resistance.The application of fragrance to silk can significantly improve the performance of silk.However,there are two key scientific problems that need to be solved:slowing down the release rate of fragrances and increasing the scent lasting time of silk.In this study,cationic and temperature-sensitive liposomes were designed and prepared to encapsulate eugenol.These fragrance-loaded liposomes significantly slowed down the release rate of the fragrance and controlled the release rate of the fragrance in a thermo-sensitive manner.The liposomes adhered to the silk through electrostatic adsorption interaction.The positive charge on the fragranceloaded liposomes neutralized much negative charge on silk and thereby increasing the adhesion efficiency.
文摘A kind of novel copolymer hydrogel of poly（N, N-dimethylaminoethyl methacrylate-co-N-isopropylacrylamide） （poly[DMAEMA/NIPAAm]） was synthesized by the initiation of K2S2O8, N, N＇-methylene-bis（acrylamide） （Bis） was used as the crosslinker. The effects of monomer content, pH and temperature on swelling ratio of the hydrogel were investigated; the thermo-sensitivity in deionized water and in physiological saline was determined. It showed that the swelling ratio of the hydrogel could be changed by changing the temperature or pH alternately. Both swelling ratio and LCST （Lower Critical Solution Temperature） of the hydrogel decreased with the increase of NIPAAm in the co-polymer content.
文摘The swelling behavior of a temperature-sensitive poly-N-isopropylacrylamide(PNIPAM) hydrogel circular cylinder is studied subjected to combined extension-torsion and varied temperature. In this regard, a semi-analytical solution is proposed for general combined loading. A finite element(FE) analysis is conducted, subjecting a hydrogel cylinder to the combined extension-torsion and the varied temperature to evaluate the validity and accuracy of the solution. A user-defined UHYPER subroutine is developed and verified under free and constrained swelling conditions. The FE results illustrate excellent agreement with the semi-analytical solution. Due to the complexity of the problem, some compositions and applied loading factors are analyzed. It is revealed that for larger cross-linked density and larger ending temperature, the cylinder yields higher stresses and smaller radial swelling deformation. Besides, the radial and hoop stresses increase by applying larger twist and axial stretch. The hoop stresses intersect at approximately R/Rout = 0.58, where the hoop stress vanishes. Besides, the axial force has direct and inverse relationships with the axial stretch and the twist, respectively. However, the resultant torsional moment behavior is complex, and the position of the maximum point varies significantly by altering the axial stretch and the twist.
文摘William Somerset Maugham was one of the most popular British writers of his era.Many of his works are closely related to China,among which is the famous novel The Painted Veil.This novel narrates the love story between the heroine Kitty,an attractive but vainglorious middle-class lady,and the intelligent bacteriologist Walter Fane.This thesis aims at exploring the hetero image of China in The Painted Veil from the perspective of imagology.It comprises four chapters.Chapter one introduces the definition of the terms“Image”and“hetero image”.Chapter two analyzes Maugham’s diversified concepts of China:one is the positive and good image,and the other is the negative image.Chapter three illustrates the specific images of China revealed in the novel The Painted Veil,on both positive and negative aspects.After the exploration of the image of China from the perspective of imagology,we can sum up that actually,the image of China in Maugham’s eyes indicated in The Painted Veil is not the real China.It is a combination of the real world observed by Maugham and the imaginative world conceived by him influenced by his own specific culture and society.
文摘At first glance,Lhapa Tsering appears modestly dressed,A:almost unassumingyet an artistic air surrounds him.A man of few words,his eyes light up with unmistakable passion the moment painting enters the conversation.His fingers lightly graze the paintbrush.
文摘Through the analysis of the actual situation and process of painting industrial steel components in Hechang Company,we have modified the mixing ratio of paint,thinner,and curing agent.Additionally,we have effectively adjusted the drying time of various paint types under different seasons and temperatures.Eventually,a painting solution suitable for our company has been developed.According to this process,the painting quality has been significantly improved,costs have been saved,the labor intensity has been reduced,and production efficiency has been remarkably enhanced.
基金supported by the National Natural Science Foundation of China(Nos.22225806,22078314,22278394,22378385)Dalian Institute of Chemical Physics(Nos.DICPI202142,DICPI202436)。
文摘Fluorogen-activating proteins(FAPs)selectively bind to specific fluorophores,inducing fluorescence activation through the inhibition of torsion of fluorophores.This binding-activation mechanism provides a highly specific and efficient fluorescence system that minimizes background signals,significantly enhancing the signal-to-noise ratio(SNR)and making it a powerful tool in live-cell imaging.The principle of binding-activation fluorescence is fundamental to point accumulation for imaging in nanoscale topography(PAINT)super-resolution imaging.However,the high binding affinity between traditional FAPfluorophore pairs limits their application in PAINT,thus hindering the rapid and dynamic imaging necessary for high-resolution cellular studies.In this work,we designed malachite green(MG)derivatives with bulky N-substituents to modulate the binding affinity of the MG-d L5^(**)fluorophore-FAP pair.This modification introduces steric hindrance in MG-dL5^(**)system,resulting in reduced binding affinity and practicability for fast,high-resolution PAINT imaging.Among the synthesized derivatives,MG-Pen showed optimal properties,enabling rapid and high-resolution PAINT imaging of dL5^(**)in living cells.This study highlights the potential of MG derivatives optimization in overcoming the limitations of fluorophore-FAP pairs for super-resolution imaging and provides a new approach for enhancing the performance of PAINT in living cell applications.
