AIM: To investigate the role of emodin in protecting the liver against fibrogenesis caused by carbon tetrachloride (CCh) in rats and to further explore the underlying mechanisms. METHODS: Rat models of experimenta...AIM: To investigate the role of emodin in protecting the liver against fibrogenesis caused by carbon tetrachloride (CCh) in rats and to further explore the underlying mechanisms. METHODS: Rat models of experimental hepatic fibrosis were established by injection with CCh; the treated rats received emodin via oral administration at a dosage of 20 mg/kg twice a week at the same time. Rats injected with olive oil served as a normal group. Histopathological changes were observed by hematoxylin and eosin staining. The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum and hepatic hydroxyproline content were assayed by biochemical analyses. The mRNA and protein relevant to hepatic stellate cell (HSC) activation in the liver were assessed using real-time reverse transcription-polymerase chain reaction (RT-PCR), immunohistochernistry, western blotting and enzymelinked immunosorbent assay.RESULTS: The degree of hepatic fibrosis increased markedly in the CCh group compared to the normal group (P 〈 0.01), and decreased markedly in the emodin group compared to the CCI4 group according to METAVIR scale (P 〈 0.01) compared with those in the normal control group (51.02 ± 10.64 IU/L and 132.28 ± 18.14 IU/L). The activities of serum ALT and AST were significantly higher in rats injected with CCh (289.25 ± 68.84 IU/L and 423.89 ± 35.67 IU/L, both P 〈 0.05). The activities of serum ALT and AST were significantly reduced by administration of emodin (176.34 ± 47.29 IU/L and 226.1 ± 44.52 IU/L, both P 〈 0.05). Compared with the normal controls (54.53 ± 13.46 mg/g), hepatic hydroxyproline content was significantly higher in rats injected with CCI4 (120.27 ± 28.47 mg/g, P 〈 0.05). Hepatic hydroxyproline content was significantly reduced in the rats treated with emodin at 20 mg/kg (71.25 ± 17.02 mg/g, P 〈 0.05). Emodin significantly protected the liver from injury by reducing serum AST and ALT activities and reducing hepatic hydroxyproline content. The mRNA levels of transforming growth factor-β1 (TGF-β1), Smad4 and α-SMA in liver tissues were significantly down-regulated in SD rats that received emodin treatment. Furthermore, significant down-regulation of serum TGF-β1 protein levels and protein expression of Smad4 and α-SMA in liver tissues was also observed in the rats. Emodin inhibited HSC activation by reducing the abundance of TGF-β1 and Smad4. CONCLUSION: Emodin protects the rat liver from CCI4-induced fibrogenesis by inhibiting HSC activation. Emodin might be a therapeutic antifibrotic agent for the treatment of hepatic fibrosis.展开更多
DEAR EDITOR, We provide an annotated checklist of the butterflies of Yunnan, which includes 356 genera and 1 300 species in six families. The number of butterfly genera and species in Yunnan accounts for 79.8% and 58....DEAR EDITOR, We provide an annotated checklist of the butterflies of Yunnan, which includes 356 genera and 1 300 species in six families. The number of butterfly genera and species in Yunnan accounts for 79.8% and 58.6% of China’s total records, respectively. Thus, our study reveals that Yunnan has the highest butterfly diversity in China. This updated checklist also reports two genera and 18 species newly recorded from China as well as 36 species first recorded from Yunnan.展开更多
Eukaryotic genome size data are important both as the basis for comparative research into genome evolution and as estimators of the cost and difficulty of genome sequencing programs for non-model organisms. In this st...Eukaryotic genome size data are important both as the basis for comparative research into genome evolution and as estimators of the cost and difficulty of genome sequencing programs for non-model organisms. In this study, the genome size of 14 species of fireflies (Lampyridae) (two genera in Lampyrinae, three genera in Luciolinae, and one genus in subfamily incertae sedis) were estimated by propidium iodide (PI)-based flow cytometry. The haploid genome sizes of Lampyridae ranged from 0.42 to 1.31 pg, a 3.1-fold span. Genome sizes of the fireflies varied within the tested subfamilies and genera. Lamprigera and Pyrocoelia species had large and small genome sizes, respectively. No correlation was found between genome size and morphological traits such as body length, body width, eye width, and antennal length. Our data provide additional information on genome size estimation of the firefly family Lampyridae. Furthermore, this study will help clarify the cost and difficulty of genome sequencing programs for non-model organisms and will help promote studies on firefly genome evolution.展开更多
Swallowtail butterflies(Papilionidae)are a historically significant butterfly group due to their colorful wing patterns,extensive morphological diversity,and phylogenetically important position as a sister group to al...Swallowtail butterflies(Papilionidae)are a historically significant butterfly group due to their colorful wing patterns,extensive morphological diversity,and phylogenetically important position as a sister group to all other butterflies and have been widely studied regarding ecological adaption,phylogeny,genetics,and evolution.Notably,they contain a unique class of pigments,i.e.,papiliochromes,which contribute to their color diversity and various biological functions such as predator avoidance and mate preference.To date,however,the genomic and genetic basis of their color diversity and papiliochrome origin in a phylogenetic and evolutionary context remain largely unknown.Here,we obtained high-quality reference genomes of 11 swallowtail butterfly species covering all tribes of Papilioninae and Parnassiinae using long-read sequencing technology.Combined with previously published butterfly genomes,we obtained robust phylogenetic relationships among tribes,overcoming the challenges of incomplete lineage sorting(ILS)and gene flow.Comprehensive genomic analyses indicated that the evolution of Papilionidae-specific conserved non-exonic elements(PSCNEs)and transcription factor binding sites(TFBSs)of patterning and transporter/cofactor genes,together with the rapid evolution of transporters/cofactors,likely promoted the origin and evolution of papiliochromes.These findings not only provide novel insights into the genomic basis of color diversity,especially papiliochrome origin in swallowtail butterflies,but also provide important data resources for exploring the evolution,ecology,and conservation of butterflies.展开更多
Butterflies are diverse in virtually all aspects of their ontogeny,including morphology,life history,and behavior.However,the developmental regulatory mechanisms underlying the important phenotypic traits of butterfli...Butterflies are diverse in virtually all aspects of their ontogeny,including morphology,life history,and behavior.However,the developmental regulatory mechanisms underlying the important phenotypic traits of butterflies at different developmental stages remain unknown.Here,we investigated the developmental regulatory profiles of butterflies based on transposase accessible chromatin sequencing(ATAC-seq)at three developmental stages in two representative species(Papilio xuthus and Kallima inachus).展开更多
Combined shear-compression tests and simulations were performed on a closed-cell aluminum foam over a wide range of loading angles in order to probe their yield behaviors under biaxial loading conditions.Combined shea...Combined shear-compression tests and simulations were performed on a closed-cell aluminum foam over a wide range of loading angles in order to probe their yield behaviors under biaxial loading conditions.Combined shear-compression tests were carried out by using a pair of cylindrical bars with beveled ends.The yield surfaces were experimentally measured and compared with various theoretical yield surface models.The cellular structures of closed-cell aluminum foams were modeled as tetrakaidecahedrons and their biaxial crushing behaviors were simulated by the finite element method.The results show that,yield initiates from the stress-concentrated corners in the specimens under combined shear-compression loading and the stress distribution is no longer uniform at the specimen/bar interfaces.In the range of cell sizes studied,the larger the foam cell size is,the higher the yield stress is.Aluminum foam density is found to be the dominant factor on its mechanical properties compared with the cell size and is much more significant in engineering practice.展开更多
The cognitive processing mechanism of humor refers to how the system of neural circuitry and pathways in the brain deals with the incongruity in a humorous manner. The past research has revealed different stages and c...The cognitive processing mechanism of humor refers to how the system of neural circuitry and pathways in the brain deals with the incongruity in a humorous manner. The past research has revealed different stages and corresponding functional brain activities involved in humor-processing in terms of time and space dimensions, highlighting the effects of the time windows of about 400 ms, 600 ms, and 900 ms. However, much less is known about humor processing in light of the frequency dimension. A total of 36 Chinese participants were recruited in this experiment, with Chinese jokes, nonjokes, and nonsensical sentences used as the stimuli. The experimental results showed that there were significant differences among conditions in the P200 effect, which signified that the incongruity detection had already been integrated and perceived at about 200 ms, prior to the semantic integration at about 400 ms. This pre-processing is specific to Chinese verbal jokes due to the simultaneous involvement of both orthographic and phonologic parts in processing Chinese characters. The analysis on the frequency dimension indicated that beta’s power particularly reflected the characteristics of different stages in Chinese verbal humor processing. Jokes’ and nonsensical sentences’ relative power changes on the beta band ranked significantly higher than that of nonjokes at about 200 ms, which suggested the existence of more difficulties in meaning construction in pre-processing the incongruities. This indicated a continuity between the analysis of event related potential (ERP) components and neural oscillations and revealed the key role of the beta frequency band in Chinese verbal joke processing.展开更多
Recently,nano theranostics,by integrating diagnostic and therapeutic functions into a nano system,have provided increasing opportunities for the design of personalized medicine in cancer.Among the construction method ...Recently,nano theranostics,by integrating diagnostic and therapeutic functions into a nano system,have provided increasing opportunities for the design of personalized medicine in cancer.Among the construction method of various theranostic nano systems,the design of single component nanoparticles which are composed of organic photosensitive dyes has become a promising approach to constructing multifunctional nano-theranostic systems,thanks to its unique advantages such as defined structure,100%loading,and high repeatability.Specifically,depending on the inherent photonic imaging and therapeutic properties of the photosensitive dyes,the multifunctional purpose which integrates theranostic effects and targeting abilities can be realized via reasonable molecular modification and supramolecular assembly.In this review,recent advances in the development of nanostructured self-assemblies of porphyrins,phthalocyanines,and boron-dipyrromethanes for theranostics are summarized.Emphasis on their design consideration and theranostic applications are presented.Additionally,prospects for clinical practice and potential challenges of this rapidly growing field are also provided.展开更多
Ras-related C3 botulinum toxin substrate 1(Racl),a member of the Rho GTPase family which plays important roles in dendritic spine morphology and plasticity,is a key regulator of cytoskeletal reorganization in dendrite...Ras-related C3 botulinum toxin substrate 1(Racl),a member of the Rho GTPase family which plays important roles in dendritic spine morphology and plasticity,is a key regulator of cytoskeletal reorganization in dendrites and spines.Here,we investigated whether and how Racl modulates synaptic transmission in mouse retinal ganglion cells(RGCs)using selective conditional knockout of Racl(Racl-cKO).Racl-cKO significantly reduced the frequency of AMPA receptor-mediated miniature excitatory postsynaptic currents,while glycine/GABA_A receptor-mediated miniature inhibitory postsynaptic currents were not affected.Although the total GluA1 protein level was increased in Racl-cKO mice,its expression in the membrane component was unchanged.RaclcKO did not affect spine-like branch density in single dendrites,but significantly reduced the dendritic complexity,which resulted in a decrease in the total number of dendritic spine-like branches.These results suggest that Racl selectively affects excitatory synaptic transmission in RGCs by modulating dendritic complexity.展开更多
Dear Editor, Butterflies are diverse in virtually all aspects of their bi- ology, ranging from behavior and biogeography to cellular biology and biochemistry, with decades of study having placed much of this variatio...Dear Editor, Butterflies are diverse in virtually all aspects of their bi- ology, ranging from behavior and biogeography to cellular biology and biochemistry, with decades of study having placed much of this variation in a well-resolved ecological context (Boogs et al., 2003). In particular, the extraordi- narily diverse wing patterns among species, populations, sexes, and even seasonal forms and their multifunctional roles from crypsis to warning coloration, mimicry, ther- moregulation and mate selection (Nijhout, 1991; Brake- field, 1999) are among the most interesting topics in evo- lutionary biology and ecology. In fact, back in 1864, H. W.展开更多
In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emul...In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emulsion copolymerization, in which monomers were added by a semi-continuous process with monomer addition under two different forms: pure monomers' mixture (monomer addition), and pre-emulsified monomers (pre-emulsion addition). Then, the hollow latex particles with different morphologies were obtained after alkali post-treatment. Influences of the monomer feeding mode on the emulsion polymerization and the particle morphology were investigated. Results showed that the pre- emulsion addition could significantly improve the polymerization stability in each step, and greatly enhance the uniformity of shell encapsulation. The sizes of the core and core/shell latex particles obtained by the pre-emulsion addition were smaller and more uniform than those synthesized by the monomer addition, and the hollow latex particles with intact morphology were generated by alkali post-treating of the core/shell latexes prepared from the pre-emulsion addition. As the core size increased, the morphology of the post-treated particles underwent evolution from hollow to collapse. Moreover, the mechanism of the particle morphological evolution was proposed.展开更多
基金Supported by National Natural Science Foundation of China,No.30873396National Science Foundation for Post-doctoral Scientists of China,No.20080430140Qiqihar Foundation for Development of Science and Technology,China,No.05090
文摘AIM: To investigate the role of emodin in protecting the liver against fibrogenesis caused by carbon tetrachloride (CCh) in rats and to further explore the underlying mechanisms. METHODS: Rat models of experimental hepatic fibrosis were established by injection with CCh; the treated rats received emodin via oral administration at a dosage of 20 mg/kg twice a week at the same time. Rats injected with olive oil served as a normal group. Histopathological changes were observed by hematoxylin and eosin staining. The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum and hepatic hydroxyproline content were assayed by biochemical analyses. The mRNA and protein relevant to hepatic stellate cell (HSC) activation in the liver were assessed using real-time reverse transcription-polymerase chain reaction (RT-PCR), immunohistochernistry, western blotting and enzymelinked immunosorbent assay.RESULTS: The degree of hepatic fibrosis increased markedly in the CCh group compared to the normal group (P 〈 0.01), and decreased markedly in the emodin group compared to the CCI4 group according to METAVIR scale (P 〈 0.01) compared with those in the normal control group (51.02 ± 10.64 IU/L and 132.28 ± 18.14 IU/L). The activities of serum ALT and AST were significantly higher in rats injected with CCh (289.25 ± 68.84 IU/L and 423.89 ± 35.67 IU/L, both P 〈 0.05). The activities of serum ALT and AST were significantly reduced by administration of emodin (176.34 ± 47.29 IU/L and 226.1 ± 44.52 IU/L, both P 〈 0.05). Compared with the normal controls (54.53 ± 13.46 mg/g), hepatic hydroxyproline content was significantly higher in rats injected with CCI4 (120.27 ± 28.47 mg/g, P 〈 0.05). Hepatic hydroxyproline content was significantly reduced in the rats treated with emodin at 20 mg/kg (71.25 ± 17.02 mg/g, P 〈 0.05). Emodin significantly protected the liver from injury by reducing serum AST and ALT activities and reducing hepatic hydroxyproline content. The mRNA levels of transforming growth factor-β1 (TGF-β1), Smad4 and α-SMA in liver tissues were significantly down-regulated in SD rats that received emodin treatment. Furthermore, significant down-regulation of serum TGF-β1 protein levels and protein expression of Smad4 and α-SMA in liver tissues was also observed in the rats. Emodin inhibited HSC activation by reducing the abundance of TGF-β1 and Smad4. CONCLUSION: Emodin protects the rat liver from CCI4-induced fibrogenesis by inhibiting HSC activation. Emodin might be a therapeutic antifibrotic agent for the treatment of hepatic fibrosis.
基金supported by the National Natural Science Foundation of China(32070482)Yunnan Provincial Science and Technology Department(Talent Project of Yunnan:202105AC160039)+2 种基金Biodiversity Conservation Program of the Ministry of Ecology and Environment,China(China BON-Butterflies)Yunnan Forestry and Grassland Bureau。
文摘DEAR EDITOR, We provide an annotated checklist of the butterflies of Yunnan, which includes 356 genera and 1 300 species in six families. The number of butterfly genera and species in Yunnan accounts for 79.8% and 58.6% of China’s total records, respectively. Thus, our study reveals that Yunnan has the highest butterfly diversity in China. This updated checklist also reports two genera and 18 species newly recorded from China as well as 36 species first recorded from Yunnan.
基金supported by grants from the National Natural Science Foundation of China(No.31472035)Yunnan Provincial Science and Technology Department(No.2014FB179)to LXY
文摘Eukaryotic genome size data are important both as the basis for comparative research into genome evolution and as estimators of the cost and difficulty of genome sequencing programs for non-model organisms. In this study, the genome size of 14 species of fireflies (Lampyridae) (two genera in Lampyrinae, three genera in Luciolinae, and one genus in subfamily incertae sedis) were estimated by propidium iodide (PI)-based flow cytometry. The haploid genome sizes of Lampyridae ranged from 0.42 to 1.31 pg, a 3.1-fold span. Genome sizes of the fireflies varied within the tested subfamilies and genera. Lamprigera and Pyrocoelia species had large and small genome sizes, respectively. No correlation was found between genome size and morphological traits such as body length, body width, eye width, and antennal length. Our data provide additional information on genome size estimation of the firefly family Lampyridae. Furthermore, this study will help clarify the cost and difficulty of genome sequencing programs for non-model organisms and will help promote studies on firefly genome evolution.
基金supported by the National Natural Science Foundation of China(31621062 to W.W.,32070482 to X.Y.L.)Chinese Academy of Sciences(“Light of West China”to X.Y.L.,XDB13000000 to W.W.)+1 种基金Yunnan Provincial Science and Technology Department(Talent Project of Yunnan:202105AC160039)Biodiversity Conservation Program of the Ministry of Ecology and Environment,China(China BON-Butterflies)。
文摘Swallowtail butterflies(Papilionidae)are a historically significant butterfly group due to their colorful wing patterns,extensive morphological diversity,and phylogenetically important position as a sister group to all other butterflies and have been widely studied regarding ecological adaption,phylogeny,genetics,and evolution.Notably,they contain a unique class of pigments,i.e.,papiliochromes,which contribute to their color diversity and various biological functions such as predator avoidance and mate preference.To date,however,the genomic and genetic basis of their color diversity and papiliochrome origin in a phylogenetic and evolutionary context remain largely unknown.Here,we obtained high-quality reference genomes of 11 swallowtail butterfly species covering all tribes of Papilioninae and Parnassiinae using long-read sequencing technology.Combined with previously published butterfly genomes,we obtained robust phylogenetic relationships among tribes,overcoming the challenges of incomplete lineage sorting(ILS)and gene flow.Comprehensive genomic analyses indicated that the evolution of Papilionidae-specific conserved non-exonic elements(PSCNEs)and transcription factor binding sites(TFBSs)of patterning and transporter/cofactor genes,together with the rapid evolution of transporters/cofactors,likely promoted the origin and evolution of papiliochromes.These findings not only provide novel insights into the genomic basis of color diversity,especially papiliochrome origin in swallowtail butterflies,but also provide important data resources for exploring the evolution,ecology,and conservation of butterflies.
基金supported by the National Natural Science Foundation of China(31621062 to W.W.,32070482 to X.Y.L.)Chinese Academy of Sciences(“Light of West China”to X.Y.L.,XDB13000000 to W.W.)。
文摘Butterflies are diverse in virtually all aspects of their ontogeny,including morphology,life history,and behavior.However,the developmental regulatory mechanisms underlying the important phenotypic traits of butterflies at different developmental stages remain unknown.Here,we investigated the developmental regulatory profiles of butterflies based on transposase accessible chromatin sequencing(ATAC-seq)at three developmental stages in two representative species(Papilio xuthus and Kallima inachus).
基金Project(2017JJ3359)supported by the Natural Science Foundation of Hunan Province,ChinaProject(KFJJ13-11M)supported by the Opening Project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology),China.
文摘Combined shear-compression tests and simulations were performed on a closed-cell aluminum foam over a wide range of loading angles in order to probe their yield behaviors under biaxial loading conditions.Combined shear-compression tests were carried out by using a pair of cylindrical bars with beveled ends.The yield surfaces were experimentally measured and compared with various theoretical yield surface models.The cellular structures of closed-cell aluminum foams were modeled as tetrakaidecahedrons and their biaxial crushing behaviors were simulated by the finite element method.The results show that,yield initiates from the stress-concentrated corners in the specimens under combined shear-compression loading and the stress distribution is no longer uniform at the specimen/bar interfaces.In the range of cell sizes studied,the larger the foam cell size is,the higher the yield stress is.Aluminum foam density is found to be the dominant factor on its mechanical properties compared with the cell size and is much more significant in engineering practice.
文摘The cognitive processing mechanism of humor refers to how the system of neural circuitry and pathways in the brain deals with the incongruity in a humorous manner. The past research has revealed different stages and corresponding functional brain activities involved in humor-processing in terms of time and space dimensions, highlighting the effects of the time windows of about 400 ms, 600 ms, and 900 ms. However, much less is known about humor processing in light of the frequency dimension. A total of 36 Chinese participants were recruited in this experiment, with Chinese jokes, nonjokes, and nonsensical sentences used as the stimuli. The experimental results showed that there were significant differences among conditions in the P200 effect, which signified that the incongruity detection had already been integrated and perceived at about 200 ms, prior to the semantic integration at about 400 ms. This pre-processing is specific to Chinese verbal jokes due to the simultaneous involvement of both orthographic and phonologic parts in processing Chinese characters. The analysis on the frequency dimension indicated that beta’s power particularly reflected the characteristics of different stages in Chinese verbal humor processing. Jokes’ and nonsensical sentences’ relative power changes on the beta band ranked significantly higher than that of nonjokes at about 200 ms, which suggested the existence of more difficulties in meaning construction in pre-processing the incongruities. This indicated a continuity between the analysis of event related potential (ERP) components and neural oscillations and revealed the key role of the beta frequency band in Chinese verbal joke processing.
基金supported by the National Natural Science Foundation of China(Grant Nos.22078066 and 22178065)
文摘Recently,nano theranostics,by integrating diagnostic and therapeutic functions into a nano system,have provided increasing opportunities for the design of personalized medicine in cancer.Among the construction method of various theranostic nano systems,the design of single component nanoparticles which are composed of organic photosensitive dyes has become a promising approach to constructing multifunctional nano-theranostic systems,thanks to its unique advantages such as defined structure,100%loading,and high repeatability.Specifically,depending on the inherent photonic imaging and therapeutic properties of the photosensitive dyes,the multifunctional purpose which integrates theranostic effects and targeting abilities can be realized via reasonable molecular modification and supramolecular assembly.In this review,recent advances in the development of nanostructured self-assemblies of porphyrins,phthalocyanines,and boron-dipyrromethanes for theranostics are summarized.Emphasis on their design consideration and theranostic applications are presented.Additionally,prospects for clinical practice and potential challenges of this rapidly growing field are also provided.
基金supported by grants from the National Natural Science Foundation of China (81790642, 31671078, and 81430007)
文摘Ras-related C3 botulinum toxin substrate 1(Racl),a member of the Rho GTPase family which plays important roles in dendritic spine morphology and plasticity,is a key regulator of cytoskeletal reorganization in dendrites and spines.Here,we investigated whether and how Racl modulates synaptic transmission in mouse retinal ganglion cells(RGCs)using selective conditional knockout of Racl(Racl-cKO).Racl-cKO significantly reduced the frequency of AMPA receptor-mediated miniature excitatory postsynaptic currents,while glycine/GABA_A receptor-mediated miniature inhibitory postsynaptic currents were not affected.Although the total GluA1 protein level was increased in Racl-cKO mice,its expression in the membrane component was unchanged.RaclcKO did not affect spine-like branch density in single dendrites,but significantly reduced the dendritic complexity,which resulted in a decrease in the total number of dendritic spine-like branches.These results suggest that Racl selectively affects excitatory synaptic transmission in RGCs by modulating dendritic complexity.
基金This project was funded by grants from the National Natural Science Foundation of China (No. 31321002 and No. 31123005), the Chinese Academy of Sciences (XDB 13000000) and from Yunnan Provincial Science and Technology Department (No. 2013HA004).
文摘Dear Editor, Butterflies are diverse in virtually all aspects of their bi- ology, ranging from behavior and biogeography to cellular biology and biochemistry, with decades of study having placed much of this variation in a well-resolved ecological context (Boogs et al., 2003). In particular, the extraordi- narily diverse wing patterns among species, populations, sexes, and even seasonal forms and their multifunctional roles from crypsis to warning coloration, mimicry, ther- moregulation and mate selection (Nijhout, 1991; Brake- field, 1999) are among the most interesting topics in evo- lutionary biology and ecology. In fact, back in 1864, H. W.
文摘In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emulsion copolymerization, in which monomers were added by a semi-continuous process with monomer addition under two different forms: pure monomers' mixture (monomer addition), and pre-emulsified monomers (pre-emulsion addition). Then, the hollow latex particles with different morphologies were obtained after alkali post-treatment. Influences of the monomer feeding mode on the emulsion polymerization and the particle morphology were investigated. Results showed that the pre- emulsion addition could significantly improve the polymerization stability in each step, and greatly enhance the uniformity of shell encapsulation. The sizes of the core and core/shell latex particles obtained by the pre-emulsion addition were smaller and more uniform than those synthesized by the monomer addition, and the hollow latex particles with intact morphology were generated by alkali post-treating of the core/shell latexes prepared from the pre-emulsion addition. As the core size increased, the morphology of the post-treated particles underwent evolution from hollow to collapse. Moreover, the mechanism of the particle morphological evolution was proposed.