Effects of CaCl2, CuCl2, ZnCl2 and PbCl2 on development and hatching success of eggs of Folsomia candida （Collembola） were studied under laboratory conditions. Thousands of healthy eggs from synchronized cultures we...Effects of CaCl2, CuCl2, ZnCl2 and PbCl2 on development and hatching success of eggs of Folsomia candida （Collembola） were studied under laboratory conditions. Thousands of healthy eggs from synchronized cultures were incubated in soils treated with different concentrations of the metals. Compared with the water control, egg hatch significantly decreased when concentrations of Cu, Pb and Zn reached 400, 1 600 and 800 mg/kg dry soil, respectively. Values of EC50（hatching）, calculated according to the exponential model （with 95% confidence limits in brackets）, were 625 （407-875）, 2 361 （2 064-2 687） and 1 763 （1 548-2 000） mg/kg dry soils for Cu, Pb and Zn, respectively. When Cu concentration reached 1 600 mg/kg dry soil, eggs became green and the percentage of green eggs changed from 5%-20% after incubation for 2 days to 15%- 30% after incubation for 4 days. At 3 200 mg Cu/kg dry soil, tissues inside eggs were black and shrunken.展开更多
One of the major innovations awaiting in electron microscopy is full three-dimensional imaging at atomic resolution.Despite the success of aberration correction to deep sub-angstrom lateral resolution,spatial resoluti...One of the major innovations awaiting in electron microscopy is full three-dimensional imaging at atomic resolution.Despite the success of aberration correction to deep sub-angstrom lateral resolution,spatial resolution in depth is still far from atomic resolution.In scanning transmission electron microscopy(STEM),this poor depth resolution is due to the limitation of the illumination angle.To overcome this physical limitation,it is essential to implement a next-generation aberration corrector in STEM that can significantly improve the depth resolution.This review discusses the capability of depth sectioning for three-dimensional imaging combined with large-angle illumination STEM.Furthermore,the statistical analysis approach remarkably improves the depth resolution,making it possible to achieve three-dimensional atomic resolution imaging at oxide surfaces.We will also discuss the future prospects of three-dimensional imaging at atomic resolution by STEM depth sectioning.展开更多
Fiber-reinforced polymer composite materials have become materials of choice for manufacturing application due to their high specific stiffness, strength and fatigue life, low density and thermal expansion coefficient...Fiber-reinforced polymer composite materials have become materials of choice for manufacturing application due to their high specific stiffness, strength and fatigue life, low density and thermal expansion coefficient. However, there are some types of defects such as porosity that form during the manufacturing processes of composites and alter their mechanical behavior and material properties. In his study, hand lay-up was conducted to fabricate samples of carbon fiber-reinforced polymer composites with three different vacuum levels in order to vary porosity content. Nondestructive evaluation, destructive techniques and mechanical testing were conducted. Nondestructive evaluation results showed the trend in percentages of porosity through-thickness. Serial sectioning images revealed significant details about the composite’s internal structure such as the volume, morphology and distribution of porosity. Mechanical testing results showed that porosity led to a decrease in both Mode I static interlaminar fracture toughness and Mode I cyclic strain energy release rate fatigue life. The fractographic micrographs showed that porosity content increased as the vacuum decreased, and it drew a relationship between fracture mechanisms and mechanical properties of the composite under different modes of loading as a result of the porosity effects. Finally, in order to accurately quantify porosity percentages included in the samples of different vacuum levels, a comparison was made between the parameters and percentages resulted from the nondestructive evaluation and mechanical testing and the features resulted from fractography and serial sectioning.展开更多
The mammalian brain is a highly complex network that consists of millions to billions of densely-interconnected neurons.Precise dissection of neural circuits at the mesoscopic level can provide important structural in...The mammalian brain is a highly complex network that consists of millions to billions of densely-interconnected neurons.Precise dissection of neural circuits at the mesoscopic level can provide important structural information for understanding the brain.Optical approaches can achieve submicron lateral resolution and achieve“optical sectioning”by a variety of means,which has the natural advantage of allowing the observation of neural circuits at the mesoscopic level.Automated whole-brain optical imaging methods based on tissue clearing or histological sectioning surpass the limitation of optical imaging depth in biological tissues and can provide delicate structural information in a large volume of tissues.Combined with various fluorescent labeling techniques,whole-brain optical imaging methods have shown great potential in the brain-wide quantitative profiling of cells,circuits,and blood vessels.In this review,we summarize the principles and implementations of various whole-brain optical imaging methods and provide some concepts regarding their future development.展开更多
[ Objective ] This study aimed to investigate the optimal method for extracting RNA from roots of medicinal plant herba violae by comparing the effects of liquid nitrogen grinding method and low-temperature sectioning...[ Objective ] This study aimed to investigate the optimal method for extracting RNA from roots of medicinal plant herba violae by comparing the effects of liquid nitrogen grinding method and low-temperature sectioning method on RNA extraction. [ Method] Roots of herba violae were respectively crushed by using liquid nitrogen grinding method and low-temperature sectioning method to extract RNA. The extraction effects of these two methods were compared based on detec- tion of RNA concentration, purity and integrity and amplification of GAPDH gene by RT-PCR. [Result] The concentration of RNA extracted by liquid nitrogen grinding method and low-temperature sectioning method was 1.21 and 3.57 p^g/~, respectively. Both RNA extracted by these two methods showed two distinct bands after agarose gel electrophoresis. The ratio of brightness of the 28S rRNA to the 18S rRNA bands was greater than 1. PCR amplification showed that the length of GAPDH gene was about 230 bp, which was consistent with the expected result. [ Conclusion ] The experimental results indicated that using low-tempera ture sectioning method to crush the roots of herba violae can meet the needs of most molecular biological experiments including gene cloning and expression analysis, which is an effective and simple method for extracting RNA from plant roots.展开更多
The quantitative microstructural analysis in recrystallized pure iron is carried out by serial sectioning experiment coupled with three-dimensional(3-D) grain reconstruction technique. The full 3-D morphology of 16254...The quantitative microstructural analysis in recrystallized pure iron is carried out by serial sectioning experiment coupled with three-dimensional(3-D) grain reconstruction technique. The full 3-D morphology of 16254 pure iron grains, which is the largest experimental 3-D grain dataset to date, is obtained. It is shown that the peak and the mean of the grain face number distribution were 10 and 13.5, respectively. For individual grains, the average trends that the highest and lowest face classes exhibited the highest affinity for mutual contact but the lowest affinity for contact with themselves are experimentally confirmed by 3-D pure iron grains. The pure iron grains are observed to have much more three-edged faces than Monte Carlo grains, resulting in relatively higher average dispersions of the grain edge distribution.展开更多
The sarcoma structure of goldfish was first analyzed by frozen section technique. The present study revealed the alkaline and acid phosphatase distribution in the head sarcoma of goldfish. And the histochemical staini...The sarcoma structure of goldfish was first analyzed by frozen section technique. The present study revealed the alkaline and acid phosphatase distribution in the head sarcoma of goldfish. And the histochemical staining in situ by calcium-cobalt method and lead nitrate method displayed a large amount of alkaline and acid phosphatases in the head sarcoma, with higher enzyme activity. The alkaline and acid phosphatases belong to hydrolases, which are widely present in various tissues. The results showed that the activity of external sarcoma is similar to the middle one, while there was more alkaline phosphatase near to the tissue sarcoma under the goldfish scales. And they have the strong activity. The study will lay the theoretical basis on enhancing the ornamental value of goldfish.展开更多
Urea-formaldehyde (UF) resin is widely used as an adhesive for the manufacture of a range of wood and fiber based products. Although the microstructure of this resin has been examined at high resolution by field-emiss...Urea-formaldehyde (UF) resin is widely used as an adhesive for the manufacture of a range of wood and fiber based products. Although the microstructure of this resin has been examined at high resolution by field-emission scanning electron microscopy and atomic force microscopy, transmission electron microscopy (TEM) has thus far not been used, perhaps because of difficulties in ultrathin sectioning this resin in cured (polymerized) state. In the technical note presented here, a novel sample preparation method is described which enabled us to examine the microstructural morphology of UF resin by transmission electron microscopy in ultrathin sections, revealing the presence of spherical particles within the resin. Our initial attempt to ultrathin section the resin directly was not successful as it was too brittle to trim blocks for sectioning. Then, we developed a sample preparation technique that involved impregnation ofPinus radiatawood tissues with the UF resin, and then embedding of resin impregnated wood tissues with Spurr’s low viscosity embedding medium, which has been widely employed in plant and wood ultrastructure work. The TEM images illustrated and the information on the microstructural morphology of the UF resin presented are based on this novel sample preparation approach.展开更多
Microtubule arrays in prothalli large-vacuolated and meristematic dividing cells of the fern Dryopteris crassirhizoma Nakai were studied using Steedman's wax, indirect immunofluorescence labelling and confocal las...Microtubule arrays in prothalli large-vacuolated and meristematic dividing cells of the fern Dryopteris crassirhizoma Nakai were studied using Steedman's wax, indirect immunofluorescence labelling and confocal laser scanning microscopy. Results showed that the use of high paraformaldehyde concentration (8%) allowed good fixation of prothallus cells, which are characterized by numerous (meristematic cells) and big (large-vacuolated cells) vacuoles. Results also plead for the efficiency of Steedman's wax embedding method in: (1) avoiding excessive use of enzyme for digesting cell wall in the process of the microtubule cytoskeleton labelling, (2) minimizing the autofluorescence effect in cells through utilization of alcohol in sample dehydration, and (3) permitting a clear visualization of microtubule patterns during the cell mitosis. Steedman's wax, coupled with immunofluorescence labelling and confocal laser scanning microscopy techniques, allows a good investigation of cell division process in plants by using simple multicellular organisms such as fern prothalli.展开更多
基金Acknowledgments This study was supported by grants from the National Natural Science Foundation of China （40671105 and 40432005）.
文摘Effects of CaCl2, CuCl2, ZnCl2 and PbCl2 on development and hatching success of eggs of Folsomia candida （Collembola） were studied under laboratory conditions. Thousands of healthy eggs from synchronized cultures were incubated in soils treated with different concentrations of the metals. Compared with the water control, egg hatch significantly decreased when concentrations of Cu, Pb and Zn reached 400, 1 600 and 800 mg/kg dry soil, respectively. Values of EC50（hatching）, calculated according to the exponential model （with 95% confidence limits in brackets）, were 625 （407-875）, 2 361 （2 064-2 687） and 1 763 （1 548-2 000） mg/kg dry soils for Cu, Pb and Zn, respectively. When Cu concentration reached 1 600 mg/kg dry soil, eggs became green and the percentage of green eggs changed from 5%-20% after incubation for 2 days to 15%- 30% after incubation for 4 days. At 3 200 mg Cu/kg dry soil, tissues inside eggs were black and shrunken.
基金Project supported by JST-PRESTO (Grant No.JPMJPR1871)JST-FOREST (Grant No.JPMJFR2033)+2 种基金JST-ERATO (Grant No.JPMJER2202)KAKENHI JSPS (Grant Nos.JP19H05788,JP21H01614,and JP24H00373)“Next Generation Electron Microscopy”social cooperation program at the University of Tokyo。
文摘One of the major innovations awaiting in electron microscopy is full three-dimensional imaging at atomic resolution.Despite the success of aberration correction to deep sub-angstrom lateral resolution,spatial resolution in depth is still far from atomic resolution.In scanning transmission electron microscopy(STEM),this poor depth resolution is due to the limitation of the illumination angle.To overcome this physical limitation,it is essential to implement a next-generation aberration corrector in STEM that can significantly improve the depth resolution.This review discusses the capability of depth sectioning for three-dimensional imaging combined with large-angle illumination STEM.Furthermore,the statistical analysis approach remarkably improves the depth resolution,making it possible to achieve three-dimensional atomic resolution imaging at oxide surfaces.We will also discuss the future prospects of three-dimensional imaging at atomic resolution by STEM depth sectioning.
文摘Fiber-reinforced polymer composite materials have become materials of choice for manufacturing application due to their high specific stiffness, strength and fatigue life, low density and thermal expansion coefficient. However, there are some types of defects such as porosity that form during the manufacturing processes of composites and alter their mechanical behavior and material properties. In his study, hand lay-up was conducted to fabricate samples of carbon fiber-reinforced polymer composites with three different vacuum levels in order to vary porosity content. Nondestructive evaluation, destructive techniques and mechanical testing were conducted. Nondestructive evaluation results showed the trend in percentages of porosity through-thickness. Serial sectioning images revealed significant details about the composite’s internal structure such as the volume, morphology and distribution of porosity. Mechanical testing results showed that porosity led to a decrease in both Mode I static interlaminar fracture toughness and Mode I cyclic strain energy release rate fatigue life. The fractographic micrographs showed that porosity content increased as the vacuum decreased, and it drew a relationship between fracture mechanisms and mechanical properties of the composite under different modes of loading as a result of the porosity effects. Finally, in order to accurately quantify porosity percentages included in the samples of different vacuum levels, a comparison was made between the parameters and percentages resulted from the nondestructive evaluation and mechanical testing and the features resulted from fractography and serial sectioning.
基金supported by the STI2030-Major Projects(2021ZD0201001 and 2021ZD0201000)the National Natural Science Foundation of China(81827901 and 32192412).
文摘The mammalian brain is a highly complex network that consists of millions to billions of densely-interconnected neurons.Precise dissection of neural circuits at the mesoscopic level can provide important structural information for understanding the brain.Optical approaches can achieve submicron lateral resolution and achieve“optical sectioning”by a variety of means,which has the natural advantage of allowing the observation of neural circuits at the mesoscopic level.Automated whole-brain optical imaging methods based on tissue clearing or histological sectioning surpass the limitation of optical imaging depth in biological tissues and can provide delicate structural information in a large volume of tissues.Combined with various fluorescent labeling techniques,whole-brain optical imaging methods have shown great potential in the brain-wide quantitative profiling of cells,circuits,and blood vessels.In this review,we summarize the principles and implementations of various whole-brain optical imaging methods and provide some concepts regarding their future development.
基金Supported by National Natural Science Foundation of China(81001700)Project of Sichuan Provincial Education Department(11ZB227,11ZB124)Research Project for the Application Foundation of Sichuan Provincial Science and Technology Department(2012JY0081)
文摘[ Objective ] This study aimed to investigate the optimal method for extracting RNA from roots of medicinal plant herba violae by comparing the effects of liquid nitrogen grinding method and low-temperature sectioning method on RNA extraction. [ Method] Roots of herba violae were respectively crushed by using liquid nitrogen grinding method and low-temperature sectioning method to extract RNA. The extraction effects of these two methods were compared based on detec- tion of RNA concentration, purity and integrity and amplification of GAPDH gene by RT-PCR. [Result] The concentration of RNA extracted by liquid nitrogen grinding method and low-temperature sectioning method was 1.21 and 3.57 p^g/~, respectively. Both RNA extracted by these two methods showed two distinct bands after agarose gel electrophoresis. The ratio of brightness of the 28S rRNA to the 18S rRNA bands was greater than 1. PCR amplification showed that the length of GAPDH gene was about 230 bp, which was consistent with the expected result. [ Conclusion ] The experimental results indicated that using low-tempera ture sectioning method to crush the roots of herba violae can meet the needs of most molecular biological experiments including gene cloning and expression analysis, which is an effective and simple method for extracting RNA from plant roots.
基金supported by the National Natural Science Foundation of China(Grant No.51571020)the National Key Research and Development Program of China(Grant No.2016YFB0700501)+1 种基金the State Key Laboratory for Advanced Metals and Materials(Grant No.2016-Z05)the fund of the Guangdong Provincial Key Laboratory for Technology and Application of Metal Toughening(Grant No.GKL201611)
文摘The quantitative microstructural analysis in recrystallized pure iron is carried out by serial sectioning experiment coupled with three-dimensional(3-D) grain reconstruction technique. The full 3-D morphology of 16254 pure iron grains, which is the largest experimental 3-D grain dataset to date, is obtained. It is shown that the peak and the mean of the grain face number distribution were 10 and 13.5, respectively. For individual grains, the average trends that the highest and lowest face classes exhibited the highest affinity for mutual contact but the lowest affinity for contact with themselves are experimentally confirmed by 3-D pure iron grains. The pure iron grains are observed to have much more three-edged faces than Monte Carlo grains, resulting in relatively higher average dispersions of the grain edge distribution.
文摘The sarcoma structure of goldfish was first analyzed by frozen section technique. The present study revealed the alkaline and acid phosphatase distribution in the head sarcoma of goldfish. And the histochemical staining in situ by calcium-cobalt method and lead nitrate method displayed a large amount of alkaline and acid phosphatases in the head sarcoma, with higher enzyme activity. The alkaline and acid phosphatases belong to hydrolases, which are widely present in various tissues. The results showed that the activity of external sarcoma is similar to the middle one, while there was more alkaline phosphatase near to the tissue sarcoma under the goldfish scales. And they have the strong activity. The study will lay the theoretical basis on enhancing the ornamental value of goldfish.
文摘Urea-formaldehyde (UF) resin is widely used as an adhesive for the manufacture of a range of wood and fiber based products. Although the microstructure of this resin has been examined at high resolution by field-emission scanning electron microscopy and atomic force microscopy, transmission electron microscopy (TEM) has thus far not been used, perhaps because of difficulties in ultrathin sectioning this resin in cured (polymerized) state. In the technical note presented here, a novel sample preparation method is described which enabled us to examine the microstructural morphology of UF resin by transmission electron microscopy in ultrathin sections, revealing the presence of spherical particles within the resin. Our initial attempt to ultrathin section the resin directly was not successful as it was too brittle to trim blocks for sectioning. Then, we developed a sample preparation technique that involved impregnation ofPinus radiatawood tissues with the UF resin, and then embedding of resin impregnated wood tissues with Spurr’s low viscosity embedding medium, which has been widely employed in plant and wood ultrastructure work. The TEM images illustrated and the information on the microstructural morphology of the UF resin presented are based on this novel sample preparation approach.
文摘Microtubule arrays in prothalli large-vacuolated and meristematic dividing cells of the fern Dryopteris crassirhizoma Nakai were studied using Steedman's wax, indirect immunofluorescence labelling and confocal laser scanning microscopy. Results showed that the use of high paraformaldehyde concentration (8%) allowed good fixation of prothallus cells, which are characterized by numerous (meristematic cells) and big (large-vacuolated cells) vacuoles. Results also plead for the efficiency of Steedman's wax embedding method in: (1) avoiding excessive use of enzyme for digesting cell wall in the process of the microtubule cytoskeleton labelling, (2) minimizing the autofluorescence effect in cells through utilization of alcohol in sample dehydration, and (3) permitting a clear visualization of microtubule patterns during the cell mitosis. Steedman's wax, coupled with immunofluorescence labelling and confocal laser scanning microscopy techniques, allows a good investigation of cell division process in plants by using simple multicellular organisms such as fern prothalli.
