AIM: To investigate the anti-tumor effects of nuclear factor-κB (NF-κB) inhibitor SN50 and related mechanisms of SGC7901 human gastric carcinoma cells. METHODS: MTT assay was used to determine the cytotoxic effects ...AIM: To investigate the anti-tumor effects of nuclear factor-κB (NF-κB) inhibitor SN50 and related mechanisms of SGC7901 human gastric carcinoma cells. METHODS: MTT assay was used to determine the cytotoxic effects of SN50 in gastric cancer cell line SGC7901. Hoechst 33258 staining was used to detect apoptosis morphological changes after SN50 treatment. Activation of autophagy was monitored with monodansylcadaverine (MDC) staining after SN50 treatment.Immunofluorescence staining was used to detect the expression of light chain 3 (LC3). Mitochondrial membrane potential was measured using the fluorescent probe JC-1. Western blotting analysis were used to determine the expression of proteins involved in apoptosis and autophagy including p53, p53 upregulated modulator of apoptosis (PUMA), damage-regulated autophagy modulator (DRAM), LC3 and Beclin 1. We detected the effects of p53-mediated autophagy activation on the apoptosis of SGC7901 cells with the p53 inhibitor pifithrin-α. RESULTS: The viability of SGC7901 cells was inhibited after SN50 treatment. Inductions in the expression of apoptotic protein p53 and PUMA as well as autophagic protein DRAM, LC3 and Beclin 1 were detected with Western blotting analysis. SN50-treated cells exhibited punctuate microtubule-associated protein 1 LC3 in immunoreactivity and MDC-labeled vesicles increased after treatment of SN50 by MDC staining. Collapse of mitochondrial membrane potential Δψ were detected for 6 to 24 h after SN50 treatment. SN50-induced increases in PUMA, DRAM, LC3 and Beclin 1 and cell death were blocked by the p53 specific inhibitor pifithrin-α. CONCLUSION: The anti-tumor activity of NF-κB inhibitors is associated with p53-mediated activation of autophagy.展开更多
Water footprint in a region is defined as the volume of water needed for the production of goods and services consumed by the local people, Ecosystem services are a kind of important services, so ecological water us...Water footprint in a region is defined as the volume of water needed for the production of goods and services consumed by the local people, Ecosystem services are a kind of important services, so ecological water use is one necessary component in water footprint. Water footprint is divided into green water footprint and blue water footprint but the former one is often ignored.In this paper waterJootprint includes blue water needed by agricultural irrigation, industrial and domestic water demand, and green water needed by crops, economic forests, livestock prochtcts, forestlalands and grasslands. The study calculates the footprint of the Jinghe River basin in 1990, 1995, 2000 and 2005 with quarto methods. Results of research show that water footprints reached 164.1 ×10^8m3, 175. 69 ×10^8m3 and 178. 45 ×10^8m3 respectively in 1990, 1995 and 2000 including that of ecological water use, but reached 77.68×10^8m3, 94.24×10^8m3, 92.92×10^8m3 and 111.36 ×10^8m3 respectively excluding that of ecological water use. Green water.footprint is much more than blue water footprint; thereby, green water plays an important role in economic development and ecological construction The dynamic change of water footprints shows that blue water use increases rapidly and that the ecological water use is occupied by economie and domestic water use. The change also shows that water use is transferred from primary industry to secondary industry In primary industry, it is transferred from crops farming to forestry, and animal agriculture. The factors impelling the change include development anticipation on econonomy; government policies, readjustment of the industrial structure, population growth, the raise of urbanization level, and structurul change of consumption, low level of waler-saving and poor ability of waste water treatment.With blue water use per unit, green water use per unit, blue water use structure and green water use structure, we analyzed the difference of the six ecologieal function districts of the Jinghe River basin. Future ecological construction may influence on blue water use of District V and District Ⅵ at middle and lower reaches. At last some suggestions are given for effective water resouree use.展开更多
AIM: To explore epigenetic changes in the gene encod- ing X chromosome-linked inhibitor of apoptosis-associ- ated factor 1 (XAF1) during esophageal carcinogenesis. METHODS: Methylation status of XAF1 was detected ...AIM: To explore epigenetic changes in the gene encod- ing X chromosome-linked inhibitor of apoptosis-associ- ated factor 1 (XAF1) during esophageal carcinogenesis. METHODS: Methylation status of XAF1 was detected by methylation-specific polymerase chain reaction (MSP) in four esophageal cancer cell lines (KYSE30, KYSE70, BICl and partially methylated in TE3 cell lines), nine cases of normal mucosa, 72 cases of pri- mary esophageal cancer and matched adjacent tissue. XAF1 expression was examined by semi-quantitative reverse transcriptional polymerase chain reaction and Western blotting before and after treatment with 5-aza- deoxycytidine (5-aza-dc), a demethylating agent. To investigate the correlation of XAF1 expression and methylation status in primary esophageal cancer, immu- nohistochemistry for XAF1 expression was performed in 32 cases of esophageal cancer and matched adjacent tissue. The association of methylation status and clini-copathological data was analyzed by logistic regression. RESULTS: MSP results were as follows: loss of XAF1 expression was found in three of four esophageal cell lines with promoter region hypermethylation (com- pletely methylated in KYSE30, KYSE70 and BIC1 cell lines and partially in TE3 cells); all nine cases of normal esophageal mucosa were unmethylated; and 54/72 (75.00%) samples from patients with esophageal can- cer were methylated, and 25/72 (34.70%) matched adjacent tissues were methylated (75.00% vs 34,70%, z2 = 23.5840, P = 0.000). mRNA level of XAF1 mea- sured with semi-quantitative reverse transcription poly- merase chain reaction was detectable only in TE3 cells, and no expression was detected in KYSE30, KYSE70 or BIC1 cells. Protein expression was not observed in KYSE30 cells by Western blotting before treatment with 5-aza-dc. After treatment, mRNA level of XAF1 was detectable in KYSE30, KYSE70 and BIC1 cells. Protein expression was detected in KYSE30 after treatment with 5-aza-dc. Immunohistochemistry was performed on 32 cases of esophageal cancer and adjacent tissue, and demonstrated XAF1 in the nucleus and cytoplasm. XAF1 staining was found in 20/32 samples of adjacent normal tissue but was present in only 8/32 samples of esophageal cancer tissue (Z2= 9.143, P = 0.002). XAF1 expression was decreased in cancer samples compared with adjacent tissues. In 32 cases of esophageal can- cer, 24/32 samples were methylated, and 8/32 esopha- geal cancer tissues were unmethylated. XAF1 staining was found in 6/8 samples of unmethylated esophageal cancer and 2/24 samples of methylated esophageal cancer tissue. XAF1 staining was inversely correlated with XAF1 promoter region methylation (Fisher's exact test, P = 0.004). Regarding methylation status and clinicopathological data, no significant differences were found in sex, age, tumor size, tumor stage, or metas- tasis with respect to methylation of XAF1 for the 72 tis- sue samples from patients with esophageal cancer. CONCLUSION: XAF1 is frequently methylated in eso- phageal cancer, and XAF1 expression is regulated by promoter region hypermethylation.展开更多
This paper presents an enhanced Root Locus diagram that consists of the representation of the phase and the magnitude of the transfer function G(s) of a system. The magnitude is represented in decibels and the phase...This paper presents an enhanced Root Locus diagram that consists of the representation of the phase and the magnitude of the transfer function G(s) of a system. The magnitude is represented in decibels and the phase is represented by colors. It also presents how to use it to calculate different kinds of controllers. An important characteristic of this diagram is that permits to read the phase and the gain margins directly and the imaginary axis cut represents the Bode diagram. It is also possible to put the grid with damping ratio ξ and frequency ωn.展开更多
AIM: To determine the functional significance of aryl hydrocarbon receptor (AhR) in gastric carcinogenesis, and to explore the possible role of AhR in gastric cancer (GC) treatment. METHODS: RT-PCR, real-time PC...AIM: To determine the functional significance of aryl hydrocarbon receptor (AhR) in gastric carcinogenesis, and to explore the possible role of AhR in gastric cancer (GC) treatment. METHODS: RT-PCR, real-time PCR, and Western blotting were performed to detect AhR expression in 39 GC tissues and five GC cell lines. AhR protein was detected by immunohistochemistry (IHC) in 290 samples: 30 chronic superficial gastritis (CSG), 30 chronic atrophic gastritis (CAG), 30 intestinal metapiasia (IN), 30 atypical hyperplasia (AH), and 70 GC. The AhR agonist tetrachlorodibenzo-para-dioxin (TCDD) was used to treat AGS cells. MTr assay and flow cytometric analysis were performed to measure the viability, cell cycle and apoptosis of AGS cells.RESULTS: AhR expression was significantly increased in GC tissues and GC cell lines. IHC results indicated that the levels of AhR expression gradually increased, with the lowest levels in CSG, followed by CAG, IM, AH and GC. AhR expression and nuclear translocation were significantly higher in GC than in precancerous tissues. TCDD inhibited proliferation of AGS cells via induction of growth arrest at the G1-S phase. CONCLUSION: AhR plays an important role in gastric carcinogenesis. AhR may be a potential therapeutic target for GC treatment.展开更多
Objective: To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cell...Objective: To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cells. Methods: A cloning and expression vector, pEGFP-NI-lac, was constructed by inserting the prokaryotic lac promoter of pUC 19 into the eukaryotic expression vector, pEGFP-N1, between the eukaryotic PCMV promoter and enhanced green fluorescent protein (EGFP) open reading frames. To assess the function of pEGFP-NI-lac, the nucleotide sequence encoding the hepatitis C virus (HCV) core protein was cloned into the multiple cloning sites. Western blotting analysis was used to detect the expression of the HCV core protein in Escherichia coli DH5a and HepG2 cells. Results: Restriction enzyme digestion and sequence analysis indicated that pEGFP-NI-lac was successfully constructed and the HCV core gene was cloned into this vector. The Western blotting results showed that pEGFP-NI-lac promoted expression of HCV core gene in prokaryotic E. coli DH5a and eukaryotic HepG2 cells. Conclusion: The pEGFP-NI-lac vector has been successfully constructed and functions in both prokaryotic and eukaryotic cells. The EGFP reporter can be used as an insert-inactivation marker for clone selection or as an expression tag. This vector can be used for cloning and expression of genes in both prokaryotic and eukaryotic cells, making gene cloning, expression and functional studies convenient as well as time- and labor-efficient展开更多
Molecularly imprinted polymers (MIPs) were prepared by the bulk polymerization using crystal violet as the template molecule, and the methacrylic acid and ethylene glycol dimetheacrylate as functional monomer and cr...Molecularly imprinted polymers (MIPs) were prepared by the bulk polymerization using crystal violet as the template molecule, and the methacrylic acid and ethylene glycol dimetheacrylate as functional monomer and cross-linker, respectively. Sys- tematic investigations of synthetic conditions were conducted. The surface morphology and recognition mechanism of the obtained polymers were studied using scanning electron microscope and spectrophotometric analysis. MIPs showed high atTmity to template molecule and were successfully applied as special solid-phase extraction sorbent for selective extraction of crystal violet from natural seawater. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chroma- tography with diodearray detection for the analysis of crystal violet was also established. MISPE columns have good recoveries for crystal violet standard solutions and good linearity was obtained over the concentration range of 0-200 ~tg L-1 (R2 〉 0.99). Finally, two natural seawater samples were investigated. The recoveries of spiked seawater on the MISPE columns were from 44.47% to 62.34%, the relative standard deviation (n=3) being in the range of 2.89%-5.96%.展开更多
We analyze the effects of average index variation on the transmission characteristics of an index-apodized long-period fiber grating (LPFG) by the transfer matrix method and study how these effects depend on the gra...We analyze the effects of average index variation on the transmission characteristics of an index-apodized long-period fiber grating (LPFG) by the transfer matrix method and study how these effects depend on the grating length, the grating profile, the modal dispersion factor, and the duty cycle of the index modulation. Apart from shifting the resonance wavelength and modifying the rejection band, average index variation can give rise to significant side lobes that may appear on the short-wavelength or long-wavelength side of the rejection band, depending on the signs of the average index change and the modal dispersion factor. Our results provide general guidance for the writing of LPFGs for the minimization of side lobes. Our analysis compares well with published experimental results and should be useful for the design and fabrication of LPFGs.展开更多
Since the 1970s,resource crisis,environmental pollution and ecological degradation have become prominent globally,and the limits to growth have always been an important theoretical and policy issue.The technological s...Since the 1970s,resource crisis,environmental pollution and ecological degradation have become prominent globally,and the limits to growth have always been an important theoretical and policy issue.The technological system of early warning and regulation based on carrying capacity evaluation has great potential in natural resource utilization,environmental management and ecosystem conservation.In this paper,the evolution of carrying capacity research and the concept of ecological carrying capacity are summarized,and the existing evaluation methods of ecological carrying capacity are classified into ecological footprint method,comprehensive index system method,ecosystem service analysis method and human appropriation of net primary productivity method.The current problems in ecological carrying capacity study were analyzed and the trend was outlooked.Combined with the special issue,the recent proceeding of ecological carrying capacity study in the Belt and Road Initiative(BRI)region was narrated,from the aspects of ecological carrying capacity evaluation method and application,the supply and consumption of ecosystem services,and the resources use and environment change.Some suggestions have been proposed to improve the accuracy and reliability of ecological carrying capacity evaluation:1)the spatial heterogeneity and temporal dynamic change of ecological carrying capacity should be explored furtherly;2)the interaction between ecological process and human activities should be simulated;3)factors such as climate change,human activities and ecological products and ecological service flows should be integrated into the evaluation system of ecological carrying capacity.展开更多
基金Supported by Health Foundation of Jiangsu Province (H20 0719)the Higher Education Foundation of Jiangsu Province (08KJB320014)+2 种基金the Natural Science Foundation of Jiangsu Province (BK2008168)Suzhou High-Level Talents Project (2008-11)the Science, Education and Health Foundation of Soochow City (SWKQ00814)
文摘AIM: To investigate the anti-tumor effects of nuclear factor-κB (NF-κB) inhibitor SN50 and related mechanisms of SGC7901 human gastric carcinoma cells. METHODS: MTT assay was used to determine the cytotoxic effects of SN50 in gastric cancer cell line SGC7901. Hoechst 33258 staining was used to detect apoptosis morphological changes after SN50 treatment. Activation of autophagy was monitored with monodansylcadaverine (MDC) staining after SN50 treatment.Immunofluorescence staining was used to detect the expression of light chain 3 (LC3). Mitochondrial membrane potential was measured using the fluorescent probe JC-1. Western blotting analysis were used to determine the expression of proteins involved in apoptosis and autophagy including p53, p53 upregulated modulator of apoptosis (PUMA), damage-regulated autophagy modulator (DRAM), LC3 and Beclin 1. We detected the effects of p53-mediated autophagy activation on the apoptosis of SGC7901 cells with the p53 inhibitor pifithrin-α. RESULTS: The viability of SGC7901 cells was inhibited after SN50 treatment. Inductions in the expression of apoptotic protein p53 and PUMA as well as autophagic protein DRAM, LC3 and Beclin 1 were detected with Western blotting analysis. SN50-treated cells exhibited punctuate microtubule-associated protein 1 LC3 in immunoreactivity and MDC-labeled vesicles increased after treatment of SN50 by MDC staining. Collapse of mitochondrial membrane potential Δψ were detected for 6 to 24 h after SN50 treatment. SN50-induced increases in PUMA, DRAM, LC3 and Beclin 1 and cell death were blocked by the p53 specific inhibitor pifithrin-α. CONCLUSION: The anti-tumor activity of NF-κB inhibitors is associated with p53-mediated activation of autophagy.
文摘Water footprint in a region is defined as the volume of water needed for the production of goods and services consumed by the local people, Ecosystem services are a kind of important services, so ecological water use is one necessary component in water footprint. Water footprint is divided into green water footprint and blue water footprint but the former one is often ignored.In this paper waterJootprint includes blue water needed by agricultural irrigation, industrial and domestic water demand, and green water needed by crops, economic forests, livestock prochtcts, forestlalands and grasslands. The study calculates the footprint of the Jinghe River basin in 1990, 1995, 2000 and 2005 with quarto methods. Results of research show that water footprints reached 164.1 ×10^8m3, 175. 69 ×10^8m3 and 178. 45 ×10^8m3 respectively in 1990, 1995 and 2000 including that of ecological water use, but reached 77.68×10^8m3, 94.24×10^8m3, 92.92×10^8m3 and 111.36 ×10^8m3 respectively excluding that of ecological water use. Green water.footprint is much more than blue water footprint; thereby, green water plays an important role in economic development and ecological construction The dynamic change of water footprints shows that blue water use increases rapidly and that the ecological water use is occupied by economie and domestic water use. The change also shows that water use is transferred from primary industry to secondary industry In primary industry, it is transferred from crops farming to forestry, and animal agriculture. The factors impelling the change include development anticipation on econonomy; government policies, readjustment of the industrial structure, population growth, the raise of urbanization level, and structurul change of consumption, low level of waler-saving and poor ability of waste water treatment.With blue water use per unit, green water use per unit, blue water use structure and green water use structure, we analyzed the difference of the six ecologieal function districts of the Jinghe River basin. Future ecological construction may influence on blue water use of District V and District Ⅵ at middle and lower reaches. At last some suggestions are given for effective water resouree use.
基金Supported by Grants from the National Basic Research Program(973 Program), No. 2012CB934002, 2010CB912802National Key Scientific Instrument Special Programme of China, No.2011YQ03013405National Science Foundation of China,No. 81121004, 81071953 and 81161120432
文摘AIM: To explore epigenetic changes in the gene encod- ing X chromosome-linked inhibitor of apoptosis-associ- ated factor 1 (XAF1) during esophageal carcinogenesis. METHODS: Methylation status of XAF1 was detected by methylation-specific polymerase chain reaction (MSP) in four esophageal cancer cell lines (KYSE30, KYSE70, BICl and partially methylated in TE3 cell lines), nine cases of normal mucosa, 72 cases of pri- mary esophageal cancer and matched adjacent tissue. XAF1 expression was examined by semi-quantitative reverse transcriptional polymerase chain reaction and Western blotting before and after treatment with 5-aza- deoxycytidine (5-aza-dc), a demethylating agent. To investigate the correlation of XAF1 expression and methylation status in primary esophageal cancer, immu- nohistochemistry for XAF1 expression was performed in 32 cases of esophageal cancer and matched adjacent tissue. The association of methylation status and clini-copathological data was analyzed by logistic regression. RESULTS: MSP results were as follows: loss of XAF1 expression was found in three of four esophageal cell lines with promoter region hypermethylation (com- pletely methylated in KYSE30, KYSE70 and BIC1 cell lines and partially in TE3 cells); all nine cases of normal esophageal mucosa were unmethylated; and 54/72 (75.00%) samples from patients with esophageal can- cer were methylated, and 25/72 (34.70%) matched adjacent tissues were methylated (75.00% vs 34,70%, z2 = 23.5840, P = 0.000). mRNA level of XAF1 mea- sured with semi-quantitative reverse transcription poly- merase chain reaction was detectable only in TE3 cells, and no expression was detected in KYSE30, KYSE70 or BIC1 cells. Protein expression was not observed in KYSE30 cells by Western blotting before treatment with 5-aza-dc. After treatment, mRNA level of XAF1 was detectable in KYSE30, KYSE70 and BIC1 cells. Protein expression was detected in KYSE30 after treatment with 5-aza-dc. Immunohistochemistry was performed on 32 cases of esophageal cancer and adjacent tissue, and demonstrated XAF1 in the nucleus and cytoplasm. XAF1 staining was found in 20/32 samples of adjacent normal tissue but was present in only 8/32 samples of esophageal cancer tissue (Z2= 9.143, P = 0.002). XAF1 expression was decreased in cancer samples compared with adjacent tissues. In 32 cases of esophageal can- cer, 24/32 samples were methylated, and 8/32 esopha- geal cancer tissues were unmethylated. XAF1 staining was found in 6/8 samples of unmethylated esophageal cancer and 2/24 samples of methylated esophageal cancer tissue. XAF1 staining was inversely correlated with XAF1 promoter region methylation (Fisher's exact test, P = 0.004). Regarding methylation status and clinicopathological data, no significant differences were found in sex, age, tumor size, tumor stage, or metas- tasis with respect to methylation of XAF1 for the 72 tis- sue samples from patients with esophageal cancer. CONCLUSION: XAF1 is frequently methylated in eso- phageal cancer, and XAF1 expression is regulated by promoter region hypermethylation.
文摘This paper presents an enhanced Root Locus diagram that consists of the representation of the phase and the magnitude of the transfer function G(s) of a system. The magnitude is represented in decibels and the phase is represented by colors. It also presents how to use it to calculate different kinds of controllers. An important characteristic of this diagram is that permits to read the phase and the gain margins directly and the imaginary axis cut represents the Bode diagram. It is also possible to put the grid with damping ratio ξ and frequency ωn.
文摘A new dispersive relation is found and a half-pow tormulas for the generalize Miodek equation under the deeaying conditions at infinity are obtained.
基金Supported by The grants from National Natural Science Foundation of China, No. 30871145, No. 30670949 and No. 30671904the grant awarded to PhD supervisor from Chinese Ministry of Education, No. 20060558010+1 种基金the grant awarded to new teacher from Chinese Ministry of Education No. 20070558288the grants from the Natural Science Foundation of Guangdong Province, No. 5300767 and No. 7001641
文摘AIM: To determine the functional significance of aryl hydrocarbon receptor (AhR) in gastric carcinogenesis, and to explore the possible role of AhR in gastric cancer (GC) treatment. METHODS: RT-PCR, real-time PCR, and Western blotting were performed to detect AhR expression in 39 GC tissues and five GC cell lines. AhR protein was detected by immunohistochemistry (IHC) in 290 samples: 30 chronic superficial gastritis (CSG), 30 chronic atrophic gastritis (CAG), 30 intestinal metapiasia (IN), 30 atypical hyperplasia (AH), and 70 GC. The AhR agonist tetrachlorodibenzo-para-dioxin (TCDD) was used to treat AGS cells. MTr assay and flow cytometric analysis were performed to measure the viability, cell cycle and apoptosis of AGS cells.RESULTS: AhR expression was significantly increased in GC tissues and GC cell lines. IHC results indicated that the levels of AhR expression gradually increased, with the lowest levels in CSG, followed by CAG, IM, AH and GC. AhR expression and nuclear translocation were significantly higher in GC than in precancerous tissues. TCDD inhibited proliferation of AGS cells via induction of growth arrest at the G1-S phase. CONCLUSION: AhR plays an important role in gastric carcinogenesis. AhR may be a potential therapeutic target for GC treatment.
基金Supported by the National High Technology Research and Development Program of China (863 Program, 2009AA02Z111)the National Natural Science Foundation of China (30872223)the Funds of the State Key Laboratory of Pathogen and Biosecurity
文摘Objective: To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cells. Methods: A cloning and expression vector, pEGFP-NI-lac, was constructed by inserting the prokaryotic lac promoter of pUC 19 into the eukaryotic expression vector, pEGFP-N1, between the eukaryotic PCMV promoter and enhanced green fluorescent protein (EGFP) open reading frames. To assess the function of pEGFP-NI-lac, the nucleotide sequence encoding the hepatitis C virus (HCV) core protein was cloned into the multiple cloning sites. Western blotting analysis was used to detect the expression of the HCV core protein in Escherichia coli DH5a and HepG2 cells. Results: Restriction enzyme digestion and sequence analysis indicated that pEGFP-NI-lac was successfully constructed and the HCV core gene was cloned into this vector. The Western blotting results showed that pEGFP-NI-lac promoted expression of HCV core gene in prokaryotic E. coli DH5a and eukaryotic HepG2 cells. Conclusion: The pEGFP-NI-lac vector has been successfully constructed and functions in both prokaryotic and eukaryotic cells. The EGFP reporter can be used as an insert-inactivation marker for clone selection or as an expression tag. This vector can be used for cloning and expression of genes in both prokaryotic and eukaryotic cells, making gene cloning, expression and functional studies convenient as well as time- and labor-efficient
基金supported by the Natural Science Foundation of China (41076065)the Major State Basic Research Development Program of China (973 Program) (2010CB428701)
文摘Molecularly imprinted polymers (MIPs) were prepared by the bulk polymerization using crystal violet as the template molecule, and the methacrylic acid and ethylene glycol dimetheacrylate as functional monomer and cross-linker, respectively. Sys- tematic investigations of synthetic conditions were conducted. The surface morphology and recognition mechanism of the obtained polymers were studied using scanning electron microscope and spectrophotometric analysis. MIPs showed high atTmity to template molecule and were successfully applied as special solid-phase extraction sorbent for selective extraction of crystal violet from natural seawater. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chroma- tography with diodearray detection for the analysis of crystal violet was also established. MISPE columns have good recoveries for crystal violet standard solutions and good linearity was obtained over the concentration range of 0-200 ~tg L-1 (R2 〉 0.99). Finally, two natural seawater samples were investigated. The recoveries of spiked seawater on the MISPE columns were from 44.47% to 62.34%, the relative standard deviation (n=3) being in the range of 2.89%-5.96%.
文摘We analyze the effects of average index variation on the transmission characteristics of an index-apodized long-period fiber grating (LPFG) by the transfer matrix method and study how these effects depend on the grating length, the grating profile, the modal dispersion factor, and the duty cycle of the index modulation. Apart from shifting the resonance wavelength and modifying the rejection band, average index variation can give rise to significant side lobes that may appear on the short-wavelength or long-wavelength side of the rejection band, depending on the signs of the average index change and the modal dispersion factor. Our results provide general guidance for the writing of LPFGs for the minimization of side lobes. Our analysis compares well with published experimental results and should be useful for the design and fabrication of LPFGs.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20010202)The Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0600)+1 种基金The National Natural Science Foundation of China(41571496,41971263)The National Key Research and Development Programme(2016YFC0503403)
文摘Since the 1970s,resource crisis,environmental pollution and ecological degradation have become prominent globally,and the limits to growth have always been an important theoretical and policy issue.The technological system of early warning and regulation based on carrying capacity evaluation has great potential in natural resource utilization,environmental management and ecosystem conservation.In this paper,the evolution of carrying capacity research and the concept of ecological carrying capacity are summarized,and the existing evaluation methods of ecological carrying capacity are classified into ecological footprint method,comprehensive index system method,ecosystem service analysis method and human appropriation of net primary productivity method.The current problems in ecological carrying capacity study were analyzed and the trend was outlooked.Combined with the special issue,the recent proceeding of ecological carrying capacity study in the Belt and Road Initiative(BRI)region was narrated,from the aspects of ecological carrying capacity evaluation method and application,the supply and consumption of ecosystem services,and the resources use and environment change.Some suggestions have been proposed to improve the accuracy and reliability of ecological carrying capacity evaluation:1)the spatial heterogeneity and temporal dynamic change of ecological carrying capacity should be explored furtherly;2)the interaction between ecological process and human activities should be simulated;3)factors such as climate change,human activities and ecological products and ecological service flows should be integrated into the evaluation system of ecological carrying capacity.