Turbulence is expected to play a relevant role in the so-called conductor gallop phenomena,namely,the high-amplitude,low-frequency oscillation of overhead power lines due to the formation of ice structures and the ens...Turbulence is expected to play a relevant role in the so-called conductor gallop phenomena,namely,the high-amplitude,low-frequency oscillation of overhead power lines due to the formation of ice structures and the ensu-ing effect that wind can have on these.In this work,the galloping time history of a wire with distorted(fixed in time)shape due to the formation of ice is analyzed numerically in the frame of afluid-solid coupling method for different wind speeds and levels of turbulence.The results show that the turbulence intensity has a moderate effect on the increase of the conductor’s aerodynamic lift and drag coefficients due to ice accretion;nevertheless,the corresponding changes in the torsion coefficient are very significant and complicated.A high turbulence intensity can affect the torsion coefficient in a certain range of attack angles and increase the torsion angle of the conductor.Through comparison of the galloping phenomena for different wind velocities,it is found that the related amplitude grows significantly with an increase of the wind speed.For a relatively large wind speed,the galloping amplitude is more sensitive to the turbulence intensity.Moreover,the larger the turbulence intensity,the larger the conductor’s vertical and horizontal galloping amplitudes after icing.The torsion angle also increases with an increase in the wind speed and turbulence intensity.展开更多
A phenoxazine based molecule termed SP has been synthesized and used as selective sensor for halogenated solvents. This molecule shows selective fast response towards halogenated solvent via naked-eye detectable chrom...A phenoxazine based molecule termed SP has been synthesized and used as selective sensor for halogenated solvents. This molecule shows selective fast response towards halogenated solvent via naked-eye detectable chromism. SP shows colorless solution when dissolved in most solvents initially but changes to blue color in chloroform under UV irradiation(λ = 365 nm) within 5 s. The luminescence spectra of SP in halogenated solvent show a large bathochromic shift(> 100 nm) with 60-fold enhanced emission intensity compared to that in halogen-free solvents. It is also worth mentioning that the photoinduced reaction between SP molecule and the halogenated solvents occurred. Based on the detailed NMR, fluorescence and mass spectra, the possible radical reaction mechanism was proposed.Different from the majority of solvatochromic sensors that based on the polarity of solvents for detection of halogenated solvents, our sensor system worked in a special展开更多
The insect cuticle,which serves as both a protective barrier and an efficient lever system for locomotion,is an extracellular matrix primarily composed of chitin and protein.The cuticle protein CPCFC characterized by ...The insect cuticle,which serves as both a protective barrier and an efficient lever system for locomotion,is an extracellular matrix primarily composed of chitin and protein.The cuticle protein CPCFC characterized by a“CFC”motif containing 2 Cys split by the insertion of 5 residues is distributed across most insect species and specifically localized in the hard part of the cuticle.However,their physiological function is not fully understood.Here,we report 2 CPCFC proteins,TcCPCFC1 and TcCPCFC2,derived from the Coleopteran insect Tribolium castaneum.We revealed that TcCPCFC1 and TcCPCFC2 were predominantly expressed during the larval and adult stages of T.castaneum,respectively.The transcription downregulation of TcCPCFC1 significantly decreased the modulus and toughness of the elytral cuticle.We found that TcCPCFC proteins have high binding affinity to chitin.We cloned and produced recombinant TcCPCFC proteins and demonstrated that the addition of TcCPCFC proteins to chitin hydrogel greatly enhanced the hydrogel's modulus and toughness by forming denser chitin fibrous networks.Our findings reveal the functional role of CPCFC proteins in enhancing mechanical properties of insect cuticle,and we validate this process in vitro,and offer a protein candidate for fabrication of advanced chitin-based materials.展开更多
Gamma-aminobutyric acid is an important nonprotein amino acid and has been extensively applied in pharmaceuticals,livestock,food additives,and so on.It is important to develop Corynebacterium glutamicum strains that c...Gamma-aminobutyric acid is an important nonprotein amino acid and has been extensively applied in pharmaceuticals,livestock,food additives,and so on.It is important to develop Corynebacterium glutamicum strains that can efciently produce gamma-aminobutyric acid from glucose.In this study,production of gamma-aminobutyric acid in C.glutamicum CGY700 was improved by construction of CO_(2) anaplerotic reaction and overexpression of citrate synthase.The co-expression of ppc encoding phosphoenolpyruvate carboxylase and gltA encoding citrate synthase was constructed and optimized in the chromosome to compensate carbon loss and conquer metabolic bottleneck.The expression of ppc and gltA were controlled by promoters P_(tac) and P_(tacM),and the optimal mode of P_(tacM-ppc)-P_(tac)-gltA was determined.Simultaneously,the genes pknG encoding serine/threonine protein kinase G and ldh encoding l-lactate dehydrogenase were deleted,and glnA2 encoding glutamine synthase was overexpressed in the chromosome.The fnal strain CGY-PG-304 constructed in this study could produce 41.17 g/L gamma-aminobutyric acid in shake fask cultivation and 58.33 g/L gamma-aminobutyric acid via FedBatch fermentation with a yield of 0.30 g/g glucose.CGY-PG-304 was constructed by genome editing;therefore,it is stable and not necessary to add any antibiotics and inducer during fermentation.展开更多
基金This work was supported in part by the National Natural Science Foundation of China[Grant No.51867013].
文摘Turbulence is expected to play a relevant role in the so-called conductor gallop phenomena,namely,the high-amplitude,low-frequency oscillation of overhead power lines due to the formation of ice structures and the ensu-ing effect that wind can have on these.In this work,the galloping time history of a wire with distorted(fixed in time)shape due to the formation of ice is analyzed numerically in the frame of afluid-solid coupling method for different wind speeds and levels of turbulence.The results show that the turbulence intensity has a moderate effect on the increase of the conductor’s aerodynamic lift and drag coefficients due to ice accretion;nevertheless,the corresponding changes in the torsion coefficient are very significant and complicated.A high turbulence intensity can affect the torsion coefficient in a certain range of attack angles and increase the torsion angle of the conductor.Through comparison of the galloping phenomena for different wind velocities,it is found that the related amplitude grows significantly with an increase of the wind speed.For a relatively large wind speed,the galloping amplitude is more sensitive to the turbulence intensity.Moreover,the larger the turbulence intensity,the larger the conductor’s vertical and horizontal galloping amplitudes after icing.The torsion angle also increases with an increase in the wind speed and turbulence intensity.
基金the Natural Science Foundation of Shandong Province (Nos. BS2014CL042, ZR2014EEP021, ZR2017MB033)the Key Research and Development Program of Shandong Province, China (Nos. 2016GSF116014 and 2017CXGC1113)+1 种基金the Start-up Grant of Shandong Jiaotong University and the National Undergraduate Innovation Training Program (No. 201611510109)the financial support from the government of Shandong Province for visiting abroad
文摘A phenoxazine based molecule termed SP has been synthesized and used as selective sensor for halogenated solvents. This molecule shows selective fast response towards halogenated solvent via naked-eye detectable chromism. SP shows colorless solution when dissolved in most solvents initially but changes to blue color in chloroform under UV irradiation(λ = 365 nm) within 5 s. The luminescence spectra of SP in halogenated solvent show a large bathochromic shift(> 100 nm) with 60-fold enhanced emission intensity compared to that in halogen-free solvents. It is also worth mentioning that the photoinduced reaction between SP molecule and the halogenated solvents occurred. Based on the detailed NMR, fluorescence and mass spectra, the possible radical reaction mechanism was proposed.Different from the majority of solvatochromic sensors that based on the polarity of solvents for detection of halogenated solvents, our sensor system worked in a special
基金supported by the Shenzhen Science and Technology Program(Grant No.KQTD20180411143628272)the National Natural Science Foundation of China(32161133010 and 32200393)+1 种基金the National Key Research and Development Program of China(2022YFD1700200)the Special Funds for Science Technology Innovation and Industrial Development of Shenzhen Dapeng New District(PT202101-02).
文摘The insect cuticle,which serves as both a protective barrier and an efficient lever system for locomotion,is an extracellular matrix primarily composed of chitin and protein.The cuticle protein CPCFC characterized by a“CFC”motif containing 2 Cys split by the insertion of 5 residues is distributed across most insect species and specifically localized in the hard part of the cuticle.However,their physiological function is not fully understood.Here,we report 2 CPCFC proteins,TcCPCFC1 and TcCPCFC2,derived from the Coleopteran insect Tribolium castaneum.We revealed that TcCPCFC1 and TcCPCFC2 were predominantly expressed during the larval and adult stages of T.castaneum,respectively.The transcription downregulation of TcCPCFC1 significantly decreased the modulus and toughness of the elytral cuticle.We found that TcCPCFC proteins have high binding affinity to chitin.We cloned and produced recombinant TcCPCFC proteins and demonstrated that the addition of TcCPCFC proteins to chitin hydrogel greatly enhanced the hydrogel's modulus and toughness by forming denser chitin fibrous networks.Our findings reveal the functional role of CPCFC proteins in enhancing mechanical properties of insect cuticle,and we validate this process in vitro,and offer a protein candidate for fabrication of advanced chitin-based materials.
基金Publication costs are funded by the National Key Research and Development Program of China(2021YFC2100900)the Key Technology Project of Inner Mongolia Autonomous Region,China(2019GG302).
文摘Gamma-aminobutyric acid is an important nonprotein amino acid and has been extensively applied in pharmaceuticals,livestock,food additives,and so on.It is important to develop Corynebacterium glutamicum strains that can efciently produce gamma-aminobutyric acid from glucose.In this study,production of gamma-aminobutyric acid in C.glutamicum CGY700 was improved by construction of CO_(2) anaplerotic reaction and overexpression of citrate synthase.The co-expression of ppc encoding phosphoenolpyruvate carboxylase and gltA encoding citrate synthase was constructed and optimized in the chromosome to compensate carbon loss and conquer metabolic bottleneck.The expression of ppc and gltA were controlled by promoters P_(tac) and P_(tacM),and the optimal mode of P_(tacM-ppc)-P_(tac)-gltA was determined.Simultaneously,the genes pknG encoding serine/threonine protein kinase G and ldh encoding l-lactate dehydrogenase were deleted,and glnA2 encoding glutamine synthase was overexpressed in the chromosome.The fnal strain CGY-PG-304 constructed in this study could produce 41.17 g/L gamma-aminobutyric acid in shake fask cultivation and 58.33 g/L gamma-aminobutyric acid via FedBatch fermentation with a yield of 0.30 g/g glucose.CGY-PG-304 was constructed by genome editing;therefore,it is stable and not necessary to add any antibiotics and inducer during fermentation.
