Waxy maize is a specialty maize that produces mainly amylopectin starch with special food or industrial values. The objective of this study was to overcome the limitations of wx mutant allele acquisition and breeding ...Waxy maize is a specialty maize that produces mainly amylopectin starch with special food or industrial values. The objective of this study was to overcome the limitations of wx mutant allele acquisition and breeding efficiency by conversion of parental lines from normal to waxy maize. The intended mutation activity was achieved by in vivo CRISPR/Cas9 machinery involving desired-target mutation of the Wx locus in the ZC01 background,abbreviated as ZC01-DTM^(wx). Triple selection was applied to segregants to obtain high genome background recovery with transgene-free wx mutations. The targeted mutation was identified, yielding six types of mutations among progeny crossed with ZC01-DTM^(wx).The amylopectin contents of the endosperm starch in mutant lines and hybrids averaged94.9%, while those of the wild-type controls were significantly(P < 0.01) lower, with an average of 76.9%. Double selection in transgene-free lines was applied using the Bar strip test and Cas9 PCR screening. The genome background recovery ratios of the lines were determined using genome-wide SNP data. That of lines used as male parents was as high as98.19% and that of lines used as female parents was as high as 86.78%. Conversion hybrids and both parental lines showed agronomic performance similar to that of their wild-type counterparts. This study provides a practical example of the efficient extension of CRISPR/Cas9 targeted mutation to industrial hybrids for transformation of a recalcitrant species.展开更多
Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stre...Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stress conditions,a new stress path for direct shear tests was proposed to model the unloading of stress caused by excavation and other processes.The effects of the initial stresses(i.e.,the normal stress and shear stress before unloading)on the shear behavior and energy conversion were investigated using laboratory tests and numerical simulations.The shear strength of a rock under constant stress or under unloading normal stress conforms to the Mohr Coulomb criterion.As the initial normal stress increases,the cohesion decreases linearly and the tangent of the internal friction angle increases linearly.Compared with the results of the tests under constant normal stress,the cohesions of the rock samples under unloading normal stress are smaller and their internal friction angles are larger.A strength envelope surface can be used to describe the relationship between the initial stresses and the failure normal stress.Shear dilatancy can decrease the total energy of the direct shear test under constant normal stress or unloading normal stress,particularly when the stress levels(the initial stresses in the test under unloading normal stress or the normal stress in the test under constant normal stress)are high.The ratio of the dissipated energy to the total energy at the moment failure occurs decreases exponentially with increasing initial stresses.The direct shear test under constant normal stress can be considered to be a special case of a direct shear test under unloading normal stress with an unloading amount of zero.展开更多
A method of conversion from whispered speech to normal speech using the extended bilinear transformation was proposed. On account of the different deviation degrees of the whisper＇s formants in different frequency ba...A method of conversion from whispered speech to normal speech using the extended bilinear transformation was proposed. On account of the different deviation degrees of the whisper＇s formants in different frequency bands, the spectrum of the whispered speech will be processed in the separate partitions of this paper. On the basis of this spectrum, we will establish a conversion function able to usefully convert whispered speech to normal speech. Because of the whisper＇s non-linear offset in relation to normal speech, this paper introduces an expansion factor in the bilinear transform function making it correspond more closely to the actual conversion demands of whispered speech to normal speech. The introduction of this factor takes the non-linear move of the spectrum and the compression of the formant bandwidth into consideration, thus effectively reducing the spectrum distortion distance in the conversion. The experiment results show that the conversion presented in this paper effectively improves both the sound quality and the intelligibility of whispered speech.展开更多
Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains com...Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains complex and not fully understood.This study aims to gain a further understanding of the energy transfer mechanism during rockfall impact and fragmentation by impact tests using a variety of rock-like sphere specimens.The experiments mainly focus on the quantitative correlation between fragmentation degree and influence factors,i.e.impact angle and velocity on steel and granite slabs.The analysis focuses on the energy distribution characteristics,energy dissipation mechanisms,and the energy conversion rate of the fragments during impact and fragmentation.The results show that there is a significant correlation between the energy conversion rate and the fragmentation degree.In normal impact tests,elasto-plastic deformation energy and fracture energy are found to be two primary categories of energy dissipation.The proportion of total kinetic energy after impact is inversely proportional to the initial energy.A comparative analysis between normal and inclined slab impact tests reveals that the impact angle significantly influences the energy conversion rate,which controls the fragmentation degree as well.In addition,the fragmentation degree is inversely proportional to the restitution coefficient.These findings contribute to a better understanding of the energy conversion mechanism during rockfall impact and fragmentation,providing valuable insight for the development of effective strategies to mitigate such rockfall hazards.展开更多
基金supported the National Transgenic Science and Technology Program(2019ZX08010-003)the National Natural Science Foundation of China(31771808)+3 种基金the National Key Research and Development Program of China(2016YFD0101803)the Key Area Research and Development Program of Guangdong Province(2018B020202008)Beijing Municipal Science and Technology Commission(D171100007717001)National Engineering Laboratory for Crop Molecular Breeding。
文摘Waxy maize is a specialty maize that produces mainly amylopectin starch with special food or industrial values. The objective of this study was to overcome the limitations of wx mutant allele acquisition and breeding efficiency by conversion of parental lines from normal to waxy maize. The intended mutation activity was achieved by in vivo CRISPR/Cas9 machinery involving desired-target mutation of the Wx locus in the ZC01 background,abbreviated as ZC01-DTM^(wx). Triple selection was applied to segregants to obtain high genome background recovery with transgene-free wx mutations. The targeted mutation was identified, yielding six types of mutations among progeny crossed with ZC01-DTM^(wx).The amylopectin contents of the endosperm starch in mutant lines and hybrids averaged94.9%, while those of the wild-type controls were significantly(P < 0.01) lower, with an average of 76.9%. Double selection in transgene-free lines was applied using the Bar strip test and Cas9 PCR screening. The genome background recovery ratios of the lines were determined using genome-wide SNP data. That of lines used as male parents was as high as98.19% and that of lines used as female parents was as high as 86.78%. Conversion hybrids and both parental lines showed agronomic performance similar to that of their wild-type counterparts. This study provides a practical example of the efficient extension of CRISPR/Cas9 targeted mutation to industrial hybrids for transformation of a recalcitrant species.
基金This research was funded by the Fundamental Research Funds for the Central Universities,CHD(Grant Nos.300102210307 and 300102210308)the National Natural Science Foundation of China(Grant Nos.41831286 and 41972297)the Natural Science Foundation of Shaanxi Province(Grant No.2020JQ-369).
文摘Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stress conditions,a new stress path for direct shear tests was proposed to model the unloading of stress caused by excavation and other processes.The effects of the initial stresses(i.e.,the normal stress and shear stress before unloading)on the shear behavior and energy conversion were investigated using laboratory tests and numerical simulations.The shear strength of a rock under constant stress or under unloading normal stress conforms to the Mohr Coulomb criterion.As the initial normal stress increases,the cohesion decreases linearly and the tangent of the internal friction angle increases linearly.Compared with the results of the tests under constant normal stress,the cohesions of the rock samples under unloading normal stress are smaller and their internal friction angles are larger.A strength envelope surface can be used to describe the relationship between the initial stresses and the failure normal stress.Shear dilatancy can decrease the total energy of the direct shear test under constant normal stress or unloading normal stress,particularly when the stress levels(the initial stresses in the test under unloading normal stress or the normal stress in the test under constant normal stress)are high.The ratio of the dissipated energy to the total energy at the moment failure occurs decreases exponentially with increasing initial stresses.The direct shear test under constant normal stress can be considered to be a special case of a direct shear test under unloading normal stress with an unloading amount of zero.
基金supported by the National Natural Science Foundation of China(61271359,61071215)Suzhou Science and Technology Development Plan(SYG201001)Key Joint Laboratory of Soochow University and JieMei Biomedical Engineering Instrument
文摘A method of conversion from whispered speech to normal speech using the extended bilinear transformation was proposed. On account of the different deviation degrees of the whisper＇s formants in different frequency bands, the spectrum of the whispered speech will be processed in the separate partitions of this paper. On the basis of this spectrum, we will establish a conversion function able to usefully convert whispered speech to normal speech. Because of the whisper＇s non-linear offset in relation to normal speech, this paper introduces an expansion factor in the bilinear transform function making it correspond more closely to the actual conversion demands of whispered speech to normal speech. The introduction of this factor takes the non-linear move of the spectrum and the compression of the formant bandwidth into consideration, thus effectively reducing the spectrum distortion distance in the conversion. The experiment results show that the conversion presented in this paper effectively improves both the sound quality and the intelligibility of whispered speech.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A2047)the General Project of the Natural Science Foundation of Sichuan Province,China(Grant No.2023NSFSC0264).
文摘Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains complex and not fully understood.This study aims to gain a further understanding of the energy transfer mechanism during rockfall impact and fragmentation by impact tests using a variety of rock-like sphere specimens.The experiments mainly focus on the quantitative correlation between fragmentation degree and influence factors,i.e.impact angle and velocity on steel and granite slabs.The analysis focuses on the energy distribution characteristics,energy dissipation mechanisms,and the energy conversion rate of the fragments during impact and fragmentation.The results show that there is a significant correlation between the energy conversion rate and the fragmentation degree.In normal impact tests,elasto-plastic deformation energy and fracture energy are found to be two primary categories of energy dissipation.The proportion of total kinetic energy after impact is inversely proportional to the initial energy.A comparative analysis between normal and inclined slab impact tests reveals that the impact angle significantly influences the energy conversion rate,which controls the fragmentation degree as well.In addition,the fragmentation degree is inversely proportional to the restitution coefficient.These findings contribute to a better understanding of the energy conversion mechanism during rockfall impact and fragmentation,providing valuable insight for the development of effective strategies to mitigate such rockfall hazards.
