The separation of ternary methanol/methyl butyl ether/1-butylchloride mixtures was investigated, which are the main components of the waste liquid. After preliminary studies on the ternary system, the integrated proce...The separation of ternary methanol/methyl butyl ether/1-butylchloride mixtures was investigated, which are the main components of the waste liquid. After preliminary studies on the ternary system, the integrated process of extraction and distillation was put forward to separate the ternary system. The results show that methanol carl be removed from the mixtures by extraction using water as the extracting agent. Through distillation of extract and dried raffinate respectively, methanol, methyl butyl ether and 1-butylchloride can be separated and recovered. In addition, the optimal volume for the extracting agent and effects of reflux ratio on the yield of product were also studied. The optimal volume ratio of the extracting agent to material is 1： 3.5, and the yield of the product increases with the increase of reflux ratio.展开更多
Non-equidistant sparse antenna arrays constructed on the basis of Latin squares are considered. A method for their construction and a synthesis algorithm are proposed,and the properties of two-dimensional antennas bas...Non-equidistant sparse antenna arrays constructed on the basis of Latin squares are considered. A method for their construction and a synthesis algorithm are proposed,and the properties of two-dimensional antennas based on them,which ensure,at a high degree of rarefaction,a sufficiently small lateral radiation are studied. The features and main characteristics of such antennas are studied.展开更多
Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over c...Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.展开更多
A survey of opinion conducted by the Observatory of Public Broadcasting in Latin America indicates that one of the biggest challenges for Brazilian public broadcasting lies in changing the perception that has been cry...A survey of opinion conducted by the Observatory of Public Broadcasting in Latin America indicates that one of the biggest challenges for Brazilian public broadcasting lies in changing the perception that has been crystallized by the public in relation to such stations. Initial analysis of the data obtained so far shows that the respondents have a negative image in relation to public media. At times, the people manifest themselves in favor of the principles that should delimit the performance of radios and TVs, such as diversity, independence, and differentiation from commercial media, but, which are not fully followed. At other times, they criticize the quality of programming and the political-governmental character of these stations. In this critical scenario, the paper presents a discussion on the challenges facing the sector considering the complex historical, cultural, and economic policy circumstances, that have contributed to the maintenance of this ＂symbolic liability＂ between media and the audience/citizens, and which reflects on the possible strategies to face the problem.展开更多
The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind...The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.展开更多
This work was undertaken to explore the potential of fruit waste materials as sources of natural antioxidants. Kernels of four varieties of mangoes of Indian origin were studied. Kernels were extracted with five diffe...This work was undertaken to explore the potential of fruit waste materials as sources of natural antioxidants. Kernels of four varieties of mangoes of Indian origin were studied. Kernels were extracted with five different solvents, tested for extraction efficiency and total phenolic content （TPC）. As the methanol proved to be the best solvent, it was used for further analysis. The methanolic extracts of kernels had reducing power （RP） and scavenged 2, 2 diphenyl-l-picryl hydrazyl （DPPH） radical, which is related to their antioxidant activity （AA）. When analyzed in HPLC, the extracts showed the presence of phenolic compounds. The extracts had the higher capacity to reduce the formation of peroxides and slow down the rate of oxidation than butylated hydroxyl toluene （BHT） in refined, bleached deodorized soybean oil （RBD SBO）. Based on the results obtained mango kernels are potential source of natural antioxidants owing to their antioxidant activity.展开更多
文摘The separation of ternary methanol/methyl butyl ether/1-butylchloride mixtures was investigated, which are the main components of the waste liquid. After preliminary studies on the ternary system, the integrated process of extraction and distillation was put forward to separate the ternary system. The results show that methanol carl be removed from the mixtures by extraction using water as the extracting agent. Through distillation of extract and dried raffinate respectively, methanol, methyl butyl ether and 1-butylchloride can be separated and recovered. In addition, the optimal volume for the extracting agent and effects of reflux ratio on the yield of product were also studied. The optimal volume ratio of the extracting agent to material is 1： 3.5, and the yield of the product increases with the increase of reflux ratio.
文摘Non-equidistant sparse antenna arrays constructed on the basis of Latin squares are considered. A method for their construction and a synthesis algorithm are proposed,and the properties of two-dimensional antennas based on them,which ensure,at a high degree of rarefaction,a sufficiently small lateral radiation are studied. The features and main characteristics of such antennas are studied.
文摘Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.
文摘A survey of opinion conducted by the Observatory of Public Broadcasting in Latin America indicates that one of the biggest challenges for Brazilian public broadcasting lies in changing the perception that has been crystallized by the public in relation to such stations. Initial analysis of the data obtained so far shows that the respondents have a negative image in relation to public media. At times, the people manifest themselves in favor of the principles that should delimit the performance of radios and TVs, such as diversity, independence, and differentiation from commercial media, but, which are not fully followed. At other times, they criticize the quality of programming and the political-governmental character of these stations. In this critical scenario, the paper presents a discussion on the challenges facing the sector considering the complex historical, cultural, and economic policy circumstances, that have contributed to the maintenance of this ＂symbolic liability＂ between media and the audience/citizens, and which reflects on the possible strategies to face the problem.
文摘The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.
文摘This work was undertaken to explore the potential of fruit waste materials as sources of natural antioxidants. Kernels of four varieties of mangoes of Indian origin were studied. Kernels were extracted with five different solvents, tested for extraction efficiency and total phenolic content （TPC）. As the methanol proved to be the best solvent, it was used for further analysis. The methanolic extracts of kernels had reducing power （RP） and scavenged 2, 2 diphenyl-l-picryl hydrazyl （DPPH） radical, which is related to their antioxidant activity （AA）. When analyzed in HPLC, the extracts showed the presence of phenolic compounds. The extracts had the higher capacity to reduce the formation of peroxides and slow down the rate of oxidation than butylated hydroxyl toluene （BHT） in refined, bleached deodorized soybean oil （RBD SBO）. Based on the results obtained mango kernels are potential source of natural antioxidants owing to their antioxidant activity.
