Powder metallurgic Ti2 AlNb alloys with W addition are sintered at 900, 1000, 1070 °C,and 1150 °C(i.e., in the O + B2, a_2+ B2 + O, a_2+ B2, and single B2 phase regions, respectively)for 12 h, followed by wa...Powder metallurgic Ti2 AlNb alloys with W addition are sintered at 900, 1000, 1070 °C,and 1150 °C(i.e., in the O + B2, a_2+ B2 + O, a_2+ B2, and single B2 phase regions, respectively)for 12 h, followed by water quenching and furnace cooling. Comparisons of phase and microstructure between quenched and furnace-cooled W-modified alloys are carried out to illustrate the phase transformation and microstructure evolution during the cooling process. Furthermore, a comparison is also made between W-modified and W-free alloys, to reveal the function of the W alloying.W addition accelerates the solutions of a_2 and O phases during the high-temperature holding, and a Widmannsta¨tten B2 + O structure, which contributes to the properties, is induced by furnace cooling from all the phase regions. The Widmannsta¨tten structure includes a B2 matrix, primary O, and secondary O precipitates. However, W alloying refines the Widmannsta¨tten structure only when the alloys are solution-treated and then cooled from the single B2 phase. Although the hardness of the W-modified alloys is lower than that of the W-free alloys sintered in the same phase region, an enhancement of hardness, 489 ± 18 HV, is obtained in the alloy solution-treated in the single B2 phase region for only 0.5 h.展开更多
AIM: To examine the effects of one-handed phacoemulsification with steep-axis incision on corneal curvature and analyze surgically induced astigmatism(SIA) on the true net power, anterior and posterior corneal surface...AIM: To examine the effects of one-handed phacoemulsification with steep-axis incision on corneal curvature and analyze surgically induced astigmatism(SIA) on the true net power, anterior and posterior corneal surfaces. METHODS: Patients with cataracts underwent onehanded phacoemulsification with a 2.4-mm steep-axis of clear corneal incision(CCI) based on true net power. CCI was created under the guidance of Verion. Central corneal thickness(CCT), keratometry readings of the true net power and anterior and posterior corneal surface were obtained using Pentacam. Biometry, such as axial length, anterior chamber depth(ACD) and white-to-white(WTW) were performed using Lenstar pre-and 3 mo postoperatively. RESULTS: The study evaluated 68 eyes of 65 patients. The mean age was 65.93±9.40 y;CCT was 529.21±37.40 μm;WTW was 11.59±0.35 mm. Regarding true net power, keratometric value at the flattest corneal meridian for the 3-mm central zone(Ks) was significantly decreased postoperatively(P=0.031). Keratometric value at the steepest corneal meridian for the 3-mm central zone(Kf) was increased postoperatively(P>0.05). Astigmatism of true net power was 1.21±0.56 D preoperatively and significantly decreased to 1.02±0.58 D postoperatively(P=0.021). On the anterior corneal surface, no significant difference in Ks and Kf was noted pre-versus postoperatively. Anterior corneal astigmatism was 1.08±0.51 D preoperativelyand significantly decreased to 0.87±0.46 D postoperatively(P=0.002). On the posterior corneal surface, Ks and Kf were significantly increased postoperatively(all P<0.05), and posterior corneal astigmatism also increased(P=0.008). The SIA values of true net power and the anterior and posterior corneal surfaces at 3 mo postoperatively were 1.26±0.63 D(range: 0.11 to 2.80 D), 1.05±0.54 D(range: 0.23 to 2.40 D), and 0.21±0.17 D(range: 0.01 to 0.07 D), respectively. CONCLUSION: One-handed phacoemulsification with steep-axis incision can effectively decrease astigmatism of true net power and anterior corneal astigmatism. In the same surgery, the difference in personal SIA potentially originated from a difference in personal corneal thickness and diameter, both CCT and WTW distance should always be measured preoperatively when planning steep-axis phacoemulsification.展开更多
To solve the problem of difficulty in identifying apple diseases in the natural environment and the low application rate of deep learning recognition networks,a lightweight ResNet(LW-ResNet)model for apple disease rec...To solve the problem of difficulty in identifying apple diseases in the natural environment and the low application rate of deep learning recognition networks,a lightweight ResNet(LW-ResNet)model for apple disease recognition is proposed.Based on the deep residual network(ResNet18),the multi-scale feature extraction layer is constructed by group convolution to realize the compression model and improve the extraction ability of different sizes of lesion features.By improving the identity mapping structure to reduce information loss.By introducing the efficient channel attention module(ECANet)to suppress noise from a complex background.The experimental results show that the average precision,recall and F1-score of the LW-ResNet on the test set are 97.80%,97.92%and 97.85%,respectively.The parameter memory is 2.32 MB,which is 94%less than that of ResNet18.Compared with the classic lightweight networks SqueezeNet and MobileNetV2,LW-ResNet has obvious advantages in recognition performance,speed,parameter memory requirement and time complexity.The proposed model has the advantages of low computational cost,low storage cost,strong real-time performance,high identification accuracy,and strong practicability,which can meet the needs of real-time identification task of apple leaf disease on resource-constrained devices.展开更多
High yield,high quality,stable yield,adaptability to growth period,and modern mechanization are the basic requirements for crops in the 21st century.Soybean oleic acid is a natural unsaturated fatty acid with strong a...High yield,high quality,stable yield,adaptability to growth period,and modern mechanization are the basic requirements for crops in the 21st century.Soybean oleic acid is a natural unsaturated fatty acid with strong antioxidant properties and stability.Known as a safe fatty acid,it has the ability to successfully prevent cardiovascular and cerebrovascular disorders.Improving the fatty acid composition of soybean seeds,can not only speed up the breeding process of high-quality high-oil and high-oleic soybeans,but also have important significance in human health,and provide the possibility for the development of soybean oil as a new energy source.Hence,the aim of this study was to analyze the high oleic acid elated gene GmSAM22 in soybean.In this research the soybean oleic acid-related gene GmSAM22 was screened out by Genome-wide association analysis,a 662 bp fragment was acquired by specific PCR amplification,and the pMD18T cloning vector was linked by the use of a seamless cloning technique.Bioinformatics analysis of the signal peptide prediction,subcellular localization,protein hydrophobicity,transmembrane region analysis,a phosphorylation site,protein secondary and tertiary structure and protein interaction analysis of the protein encoded by the SAM22 gene was carried out.The plasmid of the gene editing vector is pBK041.The overexpression vector was transformed from pCAMBIA3301 as the base vector,and overexpression vector were designed.Positive plants were obtained by genetic transformation by the pollen tube channel method.Fluorescence quantitative PCR was performed on the T2 generation plants to detect the relative expression levels in different tissues.Southern Blot was used to detect the presence of hybridization signal.Screening genes BAR,35S,and NOS in plants were identified by conventional PCR.10 seeds with high and low oleic acid content were chosen for quantitative PCR identification,and finally,the concentration and morphology of soybean fatty acids were identified by nearfar infrared spectroscopy.On 10 seeds with an upper and lower oleic acid content,a quantitative fluorescence analysis was done.In Southern blot hybridization,the SAM22 gene was integrated into the recipient soybean plant in hands of a sole copy.Fluorescence quantitative PCR appeared that the average relative expression of the SAM22 gene in roots,stems,leaves,and seeds was 1.70,1.67,3.83,and 4.41,respectively.Positive expression seeds had a 4.77%increase in oleic acid content.The level of oleic acid in the altered seeds was reduced by 4.13%when compared to CK,and it was discovered that the GmSAM22 gene could be a regulatory and secondary gene that promotes the conversion of stearic acid to oleic acid in soybean.There has not been a discussion of gene cloning or functional verification.The cloning and genetic transformation of the soybean SAM22 gene can effectively increase the content of oleic acid,which lays a foundation for the study of soybean with high oleic acid.展开更多
Dense Ti-20Al-19Nb(at.%)alloys can be cost-effectively fabricated by TiH_(2)-assisted pressureless sintering;nevertheless,the densification mechanism remains controversial without understanding the entire sintering pr...Dense Ti-20Al-19Nb(at.%)alloys can be cost-effectively fabricated by TiH_(2)-assisted pressureless sintering;nevertheless,the densification mechanism remains controversial without understanding the entire sintering process.By in situ observing the surface morphology of the Ti/Al/Nb and Ti/TiH_(2)/Al/Nb compacts upon heating,the densification mechanism of the Ti-20Al-19Nb alloys was elucidated in this study.In addition to the reported reason that the dehydrogenation of TiH_(2)provided reactive Ti,the densification of Ti-20Al-19Nb alloy was found to be strongly associated with the phase transformations upon sintering.The TiH_(2)participated in the reverse eutectoid transformation,α-Ti+δ-TiH_(2)→β-Ti,inducing theα/βand TiH_(2)/βgrain boundaries for the rapid diffusion of Al.The reaction of Ti(s)+Al(s)→TiAl_(3)(s)was then accelerated,and the majority of the Al phase was consumed in the solid state,which significantly reduced the pores from the transient liquid Al.The activation energy of the Ti-Al reaction decreased with the addition of TiH_(2),and the growth mode of the TiAl_(3)phase was changed.By removing the large pores at 700℃,the Ti-Al intermetallic phases were well connected,forming the continuous interdiffusion route for Ti,Al,and Nb.The diffusion of Nb,as well as the phase transformation ofα2→B2,was then promoted,and the ripening time for the B2 phase was increased.As a result,the density and mechanical properties were improved.The initial results of this study provided a foundation for the cost-effective fabrication of high-strength Ti-Al alloys containing refractory elements.展开更多
Suppressing the chain transfer reactions during polymerization in late-transition metal-catalyzed olefin polymerization systems is the key to obtaining high molecular weight polyolefin materials. In this work, two eff...Suppressing the chain transfer reactions during polymerization in late-transition metal-catalyzed olefin polymerization systems is the key to obtaining high molecular weight polyolefin materials. In this work, two efficient strategies(“sandwich” and rotation-restricted strategies)to retard chain transfer reactions in ethylene(co)polymerization were employed for the iminopyridyl system. Herein, a family of iminopyridyl Ni(Ⅱ)and Pd(Ⅱ) complexes with a flexible backbone and rigid axial bulky aryl substituents were designed, synthesized and characterized. In ethylene polymerization, the iminopyridyl Ni(Ⅱ) and Pd(Ⅱ) catalysts using the two strategies exhibited reasonable activities and generated highly branched polyethylenes with high molecular weights, where catalysts with dibenzosuberyl substituents exhibited significantly higher activities and produced higher molecular weight polyethylene than catalysts with 8-arylnaphthalenyl substituent. A similar trend of activities and molecular weights was also found in the copolymerization of ethylene with MA using the Pd(Ⅱ) catalysts. Moreover, highly branched E-MA copolymers with moderate to high molecular weights and high incorporation ratios(up to 17.4 mol%) were generated with the two Pd(Ⅱ) catalysts. Most interestingly, as compared with the dibenzhydryl Ni(Ⅱ) and Pd(Ⅱ) catalysts, the catalysts using the two strategies exhibited a superior ability to retard the chain transfer reactions and generated polymers and copolymers with 1-2 orders of magnitude higher molecular weights during ethylene(co)polymerization.展开更多
基金the National Natural Science Foundation of China(Grant Nos.51474156 and U1660201)the National High Technology Research and Development Program(‘‘863" Program)of China(Grant No.2015AA042504)for financial support
文摘Powder metallurgic Ti2 AlNb alloys with W addition are sintered at 900, 1000, 1070 °C,and 1150 °C(i.e., in the O + B2, a_2+ B2 + O, a_2+ B2, and single B2 phase regions, respectively)for 12 h, followed by water quenching and furnace cooling. Comparisons of phase and microstructure between quenched and furnace-cooled W-modified alloys are carried out to illustrate the phase transformation and microstructure evolution during the cooling process. Furthermore, a comparison is also made between W-modified and W-free alloys, to reveal the function of the W alloying.W addition accelerates the solutions of a_2 and O phases during the high-temperature holding, and a Widmannsta¨tten B2 + O structure, which contributes to the properties, is induced by furnace cooling from all the phase regions. The Widmannsta¨tten structure includes a B2 matrix, primary O, and secondary O precipitates. However, W alloying refines the Widmannsta¨tten structure only when the alloys are solution-treated and then cooled from the single B2 phase. Although the hardness of the W-modified alloys is lower than that of the W-free alloys sintered in the same phase region, an enhancement of hardness, 489 ± 18 HV, is obtained in the alloy solution-treated in the single B2 phase region for only 0.5 h.
基金Supported by the Jiangsu Province Science and Technology Department of Social Development Major Projects-Key Diseases Standardization Diagnosis and Treatment Projects(No.BE2016699)
文摘AIM: To examine the effects of one-handed phacoemulsification with steep-axis incision on corneal curvature and analyze surgically induced astigmatism(SIA) on the true net power, anterior and posterior corneal surfaces. METHODS: Patients with cataracts underwent onehanded phacoemulsification with a 2.4-mm steep-axis of clear corneal incision(CCI) based on true net power. CCI was created under the guidance of Verion. Central corneal thickness(CCT), keratometry readings of the true net power and anterior and posterior corneal surface were obtained using Pentacam. Biometry, such as axial length, anterior chamber depth(ACD) and white-to-white(WTW) were performed using Lenstar pre-and 3 mo postoperatively. RESULTS: The study evaluated 68 eyes of 65 patients. The mean age was 65.93±9.40 y;CCT was 529.21±37.40 μm;WTW was 11.59±0.35 mm. Regarding true net power, keratometric value at the flattest corneal meridian for the 3-mm central zone(Ks) was significantly decreased postoperatively(P=0.031). Keratometric value at the steepest corneal meridian for the 3-mm central zone(Kf) was increased postoperatively(P>0.05). Astigmatism of true net power was 1.21±0.56 D preoperatively and significantly decreased to 1.02±0.58 D postoperatively(P=0.021). On the anterior corneal surface, no significant difference in Ks and Kf was noted pre-versus postoperatively. Anterior corneal astigmatism was 1.08±0.51 D preoperativelyand significantly decreased to 0.87±0.46 D postoperatively(P=0.002). On the posterior corneal surface, Ks and Kf were significantly increased postoperatively(all P<0.05), and posterior corneal astigmatism also increased(P=0.008). The SIA values of true net power and the anterior and posterior corneal surfaces at 3 mo postoperatively were 1.26±0.63 D(range: 0.11 to 2.80 D), 1.05±0.54 D(range: 0.23 to 2.40 D), and 0.21±0.17 D(range: 0.01 to 0.07 D), respectively. CONCLUSION: One-handed phacoemulsification with steep-axis incision can effectively decrease astigmatism of true net power and anterior corneal astigmatism. In the same surgery, the difference in personal SIA potentially originated from a difference in personal corneal thickness and diameter, both CCT and WTW distance should always be measured preoperatively when planning steep-axis phacoemulsification.
基金funded by the Science and Technology Development Program of Jilin Province(20190301024NY)the Precision Agriculture and Big Data Engineering Research Center of Jilin Province(2020C005).
文摘To solve the problem of difficulty in identifying apple diseases in the natural environment and the low application rate of deep learning recognition networks,a lightweight ResNet(LW-ResNet)model for apple disease recognition is proposed.Based on the deep residual network(ResNet18),the multi-scale feature extraction layer is constructed by group convolution to realize the compression model and improve the extraction ability of different sizes of lesion features.By improving the identity mapping structure to reduce information loss.By introducing the efficient channel attention module(ECANet)to suppress noise from a complex background.The experimental results show that the average precision,recall and F1-score of the LW-ResNet on the test set are 97.80%,97.92%and 97.85%,respectively.The parameter memory is 2.32 MB,which is 94%less than that of ResNet18.Compared with the classic lightweight networks SqueezeNet and MobileNetV2,LW-ResNet has obvious advantages in recognition performance,speed,parameter memory requirement and time complexity.The proposed model has the advantages of low computational cost,low storage cost,strong real-time performance,high identification accuracy,and strong practicability,which can meet the needs of real-time identification task of apple leaf disease on resource-constrained devices.
基金funded by the National Major Special Project for Breeding New Varieties of Genetically Modified Organisms(2016ZX08004-004)National Natural Science Foundation of China(31771817).
文摘High yield,high quality,stable yield,adaptability to growth period,and modern mechanization are the basic requirements for crops in the 21st century.Soybean oleic acid is a natural unsaturated fatty acid with strong antioxidant properties and stability.Known as a safe fatty acid,it has the ability to successfully prevent cardiovascular and cerebrovascular disorders.Improving the fatty acid composition of soybean seeds,can not only speed up the breeding process of high-quality high-oil and high-oleic soybeans,but also have important significance in human health,and provide the possibility for the development of soybean oil as a new energy source.Hence,the aim of this study was to analyze the high oleic acid elated gene GmSAM22 in soybean.In this research the soybean oleic acid-related gene GmSAM22 was screened out by Genome-wide association analysis,a 662 bp fragment was acquired by specific PCR amplification,and the pMD18T cloning vector was linked by the use of a seamless cloning technique.Bioinformatics analysis of the signal peptide prediction,subcellular localization,protein hydrophobicity,transmembrane region analysis,a phosphorylation site,protein secondary and tertiary structure and protein interaction analysis of the protein encoded by the SAM22 gene was carried out.The plasmid of the gene editing vector is pBK041.The overexpression vector was transformed from pCAMBIA3301 as the base vector,and overexpression vector were designed.Positive plants were obtained by genetic transformation by the pollen tube channel method.Fluorescence quantitative PCR was performed on the T2 generation plants to detect the relative expression levels in different tissues.Southern Blot was used to detect the presence of hybridization signal.Screening genes BAR,35S,and NOS in plants were identified by conventional PCR.10 seeds with high and low oleic acid content were chosen for quantitative PCR identification,and finally,the concentration and morphology of soybean fatty acids were identified by nearfar infrared spectroscopy.On 10 seeds with an upper and lower oleic acid content,a quantitative fluorescence analysis was done.In Southern blot hybridization,the SAM22 gene was integrated into the recipient soybean plant in hands of a sole copy.Fluorescence quantitative PCR appeared that the average relative expression of the SAM22 gene in roots,stems,leaves,and seeds was 1.70,1.67,3.83,and 4.41,respectively.Positive expression seeds had a 4.77%increase in oleic acid content.The level of oleic acid in the altered seeds was reduced by 4.13%when compared to CK,and it was discovered that the GmSAM22 gene could be a regulatory and secondary gene that promotes the conversion of stearic acid to oleic acid in soybean.There has not been a discussion of gene cloning or functional verification.The cloning and genetic transformation of the soybean SAM22 gene can effectively increase the content of oleic acid,which lays a foundation for the study of soybean with high oleic acid.
基金the National Natural Science Foundation of China(Grant No.52171027)the Beijing Institute of Technology Research Fund Program for Young Scholars(Grant No.202008002).
文摘Dense Ti-20Al-19Nb(at.%)alloys can be cost-effectively fabricated by TiH_(2)-assisted pressureless sintering;nevertheless,the densification mechanism remains controversial without understanding the entire sintering process.By in situ observing the surface morphology of the Ti/Al/Nb and Ti/TiH_(2)/Al/Nb compacts upon heating,the densification mechanism of the Ti-20Al-19Nb alloys was elucidated in this study.In addition to the reported reason that the dehydrogenation of TiH_(2)provided reactive Ti,the densification of Ti-20Al-19Nb alloy was found to be strongly associated with the phase transformations upon sintering.The TiH_(2)participated in the reverse eutectoid transformation,α-Ti+δ-TiH_(2)→β-Ti,inducing theα/βand TiH_(2)/βgrain boundaries for the rapid diffusion of Al.The reaction of Ti(s)+Al(s)→TiAl_(3)(s)was then accelerated,and the majority of the Al phase was consumed in the solid state,which significantly reduced the pores from the transient liquid Al.The activation energy of the Ti-Al reaction decreased with the addition of TiH_(2),and the growth mode of the TiAl_(3)phase was changed.By removing the large pores at 700℃,the Ti-Al intermetallic phases were well connected,forming the continuous interdiffusion route for Ti,Al,and Nb.The diffusion of Nb,as well as the phase transformation ofα2→B2,was then promoted,and the ripening time for the B2 phase was increased.As a result,the density and mechanical properties were improved.The initial results of this study provided a foundation for the cost-effective fabrication of high-strength Ti-Al alloys containing refractory elements.
基金Natural Science Foundation of Anhui Province(No.2108085Y06)Anhui Provincial Key Laboratory Open Project Foundation(No.LCECSC-01).
文摘Suppressing the chain transfer reactions during polymerization in late-transition metal-catalyzed olefin polymerization systems is the key to obtaining high molecular weight polyolefin materials. In this work, two efficient strategies(“sandwich” and rotation-restricted strategies)to retard chain transfer reactions in ethylene(co)polymerization were employed for the iminopyridyl system. Herein, a family of iminopyridyl Ni(Ⅱ)and Pd(Ⅱ) complexes with a flexible backbone and rigid axial bulky aryl substituents were designed, synthesized and characterized. In ethylene polymerization, the iminopyridyl Ni(Ⅱ) and Pd(Ⅱ) catalysts using the two strategies exhibited reasonable activities and generated highly branched polyethylenes with high molecular weights, where catalysts with dibenzosuberyl substituents exhibited significantly higher activities and produced higher molecular weight polyethylene than catalysts with 8-arylnaphthalenyl substituent. A similar trend of activities and molecular weights was also found in the copolymerization of ethylene with MA using the Pd(Ⅱ) catalysts. Moreover, highly branched E-MA copolymers with moderate to high molecular weights and high incorporation ratios(up to 17.4 mol%) were generated with the two Pd(Ⅱ) catalysts. Most interestingly, as compared with the dibenzhydryl Ni(Ⅱ) and Pd(Ⅱ) catalysts, the catalysts using the two strategies exhibited a superior ability to retard the chain transfer reactions and generated polymers and copolymers with 1-2 orders of magnitude higher molecular weights during ethylene(co)polymerization.
