There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic t...There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic tiles. The average production of EBP is about Ig million tons per year. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks. The maximal amount of CFA should be up to 50%.展开更多
The feasibility of utilization of flue gas desulfurization （FGD） gypsum and Class-C fly ash （CFA） to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gyps...The feasibility of utilization of flue gas desulfurization （FGD） gypsum and Class-C fly ash （CFA） to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum （FGDG） which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of A1-O/Si-O bonds and Si-O-Si / Si-O-A1 bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.展开更多
Fly ash particles are usually spherical and based on their chemical composition;they are categorized into two classes: C and F. This study compares the microstructural, mechanical and thermal properties of extruded ri...Fly ash particles are usually spherical and based on their chemical composition;they are categorized into two classes: C and F. This study compares the microstructural, mechanical and thermal properties of extruded rigid PVC foam composites reinforced with class C and class F fly ash. The mechanical properties: such as tensile and flexural strength of composites containing class C fly ash were superior to the composites containing class F fly ash particles. Composites containing 6 phr class C fly ash showed a 24% improvement in the tensile strength in comparison to a mere 0.5% increase in composites reinforced with class F fly ash. Similarly, the addition of 6 phr of class F fly ash to the PVC foam matrix resulted in a 5.74% decrease in the flexural strength, while incorporating the same amount of class C fly ash led to a 95% increase in flexural strength. The impact strength of the composites decreased as the amount of either type of fly ash increased in the composites indicating that fly ash particles improve the rigidity of the PVC foam composites. No significant changes were observed in the thermal properties of the composites containing either type of fly ash particles. However, the thermo-mechanical properties measured by DMA indicated a steep increase in the viscoelastic properties of composites reinforced with class C flyash. The microstructural properties studied by Scanning Electron Microscopy (SEM) confirmed that fly ash particles were mechanically interlocked in the PVC matrix with good interfacial interaction with the matrix. However, particle agglomeration and debonding was observed in composites reinforced with higher amounts of fly ash.展开更多
This research analyzes the growth impacts promoted by C class in the process of the freezing of the Brazilian industry and increased imports. This emerging market, called class C, which is incorporated in part by the ...This research analyzes the growth impacts promoted by C class in the process of the freezing of the Brazilian industry and increased imports. This emerging market, called class C, which is incorporated in part by the low-income segment, presents distinct characteristics and needs and for this precise reason eventually burdens the short-term production of Brazilian companies, which feel the need to opt for the importation of basic commodities, manufactured, and semi-manufactured goods, in order to maintain a market share and return on their investments. Although this fact is actually part of a trend of global economic transformation, here it is due to a number of irregular actions taken by the Brazilian government facing a short-term political need. Stemming from quantitative researches and qualitative data, this paper sought to learn more about the consumers＇ profile and draw up some recommendations for the organizations, in order to be better prepared to face this new demand. This paper also sought to know the actions already undertaken by a large cosmetics company, parts of whose products aim at class C.展开更多
Objective:To determine the occurrence of class A and class Cβ-Iactamase genes and their cooccurrence in Indian Enterobacteriaceae.Methods:52 third generation cephalosporin resistant isolates were phenotypically detec...Objective:To determine the occurrence of class A and class Cβ-Iactamase genes and their cooccurrence in Indian Enterobacteriaceae.Methods:52 third generation cephalosporin resistant isolates were phenotypically detected by combination disk method and screened by PCR to identify class A and class C typeβ-lactamase genes.Results:Of the 52 isolates,94.2%（49） were found harboring any of the bla<sub>?</sub>,bla<sub>CTX-M</sub>,bla<sub>SHV</sub> and bla<sub>TEM</sub> were present in 82.6%（43/52）, 59.6%（31/52）,and 42.3%（22/52） isolates,respectively.Of the 49 ESBL positive isolates 57.1% （28/49） showed co-occurrence of bla<sub>ampC</sub>with bla<sub>?</sub>.On the contrary,the collection from 2009 showed their co-occurrence in 81.4%isolates.Conclusions:The comparative study shows a downward trend for co-existence of bla<sub>?</sub> with bla<sub>ampC</sub> from 2009 to 2010.Further large scale studies are needed to address the co-occurrence of class A and class Cβ-lactamases in India and the resistance trend occurring over a period of time.展开更多
文摘There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic tiles. The average production of EBP is about Ig million tons per year. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks. The maximal amount of CFA should be up to 50%.
基金Funded by the National Natural Science Foundation of China(Nos.51208370,51172164)the Specialized Research Fund for the Doctoral Program of Higher Education(Nos.20110072120046,20090072110010)of China
文摘The feasibility of utilization of flue gas desulfurization （FGD） gypsum and Class-C fly ash （CFA） to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum （FGDG） which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of A1-O/Si-O bonds and Si-O-Si / Si-O-A1 bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.
文摘Fly ash particles are usually spherical and based on their chemical composition;they are categorized into two classes: C and F. This study compares the microstructural, mechanical and thermal properties of extruded rigid PVC foam composites reinforced with class C and class F fly ash. The mechanical properties: such as tensile and flexural strength of composites containing class C fly ash were superior to the composites containing class F fly ash particles. Composites containing 6 phr class C fly ash showed a 24% improvement in the tensile strength in comparison to a mere 0.5% increase in composites reinforced with class F fly ash. Similarly, the addition of 6 phr of class F fly ash to the PVC foam matrix resulted in a 5.74% decrease in the flexural strength, while incorporating the same amount of class C fly ash led to a 95% increase in flexural strength. The impact strength of the composites decreased as the amount of either type of fly ash increased in the composites indicating that fly ash particles improve the rigidity of the PVC foam composites. No significant changes were observed in the thermal properties of the composites containing either type of fly ash particles. However, the thermo-mechanical properties measured by DMA indicated a steep increase in the viscoelastic properties of composites reinforced with class C flyash. The microstructural properties studied by Scanning Electron Microscopy (SEM) confirmed that fly ash particles were mechanically interlocked in the PVC matrix with good interfacial interaction with the matrix. However, particle agglomeration and debonding was observed in composites reinforced with higher amounts of fly ash.
文摘This research analyzes the growth impacts promoted by C class in the process of the freezing of the Brazilian industry and increased imports. This emerging market, called class C, which is incorporated in part by the low-income segment, presents distinct characteristics and needs and for this precise reason eventually burdens the short-term production of Brazilian companies, which feel the need to opt for the importation of basic commodities, manufactured, and semi-manufactured goods, in order to maintain a market share and return on their investments. Although this fact is actually part of a trend of global economic transformation, here it is due to a number of irregular actions taken by the Brazilian government facing a short-term political need. Stemming from quantitative researches and qualitative data, this paper sought to learn more about the consumers＇ profile and draw up some recommendations for the organizations, in order to be better prepared to face this new demand. This paper also sought to know the actions already undertaken by a large cosmetics company, parts of whose products aim at class C.
基金Partially funded by Department of Science & Technology,Ministry of Science & Technology,Govt.of India under Scientist Project SR/FT/L-111/2006
文摘Objective:To determine the occurrence of class A and class Cβ-Iactamase genes and their cooccurrence in Indian Enterobacteriaceae.Methods:52 third generation cephalosporin resistant isolates were phenotypically detected by combination disk method and screened by PCR to identify class A and class C typeβ-lactamase genes.Results:Of the 52 isolates,94.2%（49） were found harboring any of the bla<sub>?</sub>,bla<sub>CTX-M</sub>,bla<sub>SHV</sub> and bla<sub>TEM</sub> were present in 82.6%（43/52）, 59.6%（31/52）,and 42.3%（22/52） isolates,respectively.Of the 49 ESBL positive isolates 57.1% （28/49） showed co-occurrence of bla<sub>ampC</sub>with bla<sub>?</sub>.On the contrary,the collection from 2009 showed their co-occurrence in 81.4%isolates.Conclusions:The comparative study shows a downward trend for co-existence of bla<sub>?</sub> with bla<sub>ampC</sub> from 2009 to 2010.Further large scale studies are needed to address the co-occurrence of class A and class Cβ-lactamases in India and the resistance trend occurring over a period of time.
