The use of local materials is an important part of sustainability for the concrete industry. The declining availability of aggregate resources in many areas has the potential to result in the use of alternative aggreg...The use of local materials is an important part of sustainability for the concrete industry. The declining availability of aggregate resources in many areas has the potential to result in the use of alternative aggregates of lower quality, which can require higher cementitious materials contents, or the use of aggregates shipped from greater distance. In some markets, manufactured sands are replacing natural sands, which can adversely impact the rheology of cementitious mixtures. The use of certain chemical admixtures has been found to often minimize the need to increase cement and water contents in order to overcome the loss of workability that can accompany aggregate sources which feature flat, elongated, angular, and rough particles. In this study, a wide range of natural and manufactured sands were characterized for gradation, mineralogy, shape, texture, and cleanliness, and also evaluated for their effect on mortar rheology with and without a VMA （viscosity modifying agent） type chemical admixture. Use of the VMA is shown to mitigate the rheological effect of certain sands, and in some cases can allow for optimizing the mixture to lower paste contents. In the case of PCP （polycarboxylate）-based superplasticizers, attention is drawn to the increased dose required to achieve target workability versus superplasticizers based on NSFC （naphthalene sulfonate condensate） when swellable clays are present in the very fine fraction of certain aggregate sources. The use of sands with higher fines contents are also shown to increase the workability provided the fines are of appropriate quality.展开更多
The mandatory preclinical safety evaluation is an essential prerequisite to obtain the qualitative and effective medicines. Due to the fact that drugs may reveal genotoxic properties, the investigation of their mutage...The mandatory preclinical safety evaluation is an essential prerequisite to obtain the qualitative and effective medicines. Due to the fact that drugs may reveal genotoxic properties, the investigation of their mutagenic activity is an obligatory part of the preclinical drug safety program. The aim of the research is to study mutagenic properties of a new original immunomodulator Arglabin native in tablets in the induced test of gene mutations （the Ames test） on Salmonella typhimurium strains. Materials and methods： Four strains of S. typhimurium TA98, TA100, TA1535, and TA1537 were used to assess the mutagenicity in the Ames test. Results and conclusions： No statistically reliable dose-dependent increase in the number of revertant colonies of Salmonella typhimurium has been observed in the presence of the given drug within the investigated dose ranges from 5.0 to 100.0 μg/mL for strains TA100 and TA1535, and from 5.0 to 250 μg/mL for strains TA98 and TA1537 against the baseline of spantaneous mutations. Arglabin native in tablets does not reveal a mutagenic activity within the studied dose ranges on Salmonella typhimurium strains TA98, TA100, TA1535, TA1537.展开更多
文摘The use of local materials is an important part of sustainability for the concrete industry. The declining availability of aggregate resources in many areas has the potential to result in the use of alternative aggregates of lower quality, which can require higher cementitious materials contents, or the use of aggregates shipped from greater distance. In some markets, manufactured sands are replacing natural sands, which can adversely impact the rheology of cementitious mixtures. The use of certain chemical admixtures has been found to often minimize the need to increase cement and water contents in order to overcome the loss of workability that can accompany aggregate sources which feature flat, elongated, angular, and rough particles. In this study, a wide range of natural and manufactured sands were characterized for gradation, mineralogy, shape, texture, and cleanliness, and also evaluated for their effect on mortar rheology with and without a VMA （viscosity modifying agent） type chemical admixture. Use of the VMA is shown to mitigate the rheological effect of certain sands, and in some cases can allow for optimizing the mixture to lower paste contents. In the case of PCP （polycarboxylate）-based superplasticizers, attention is drawn to the increased dose required to achieve target workability versus superplasticizers based on NSFC （naphthalene sulfonate condensate） when swellable clays are present in the very fine fraction of certain aggregate sources. The use of sands with higher fines contents are also shown to increase the workability provided the fines are of appropriate quality.
文摘The mandatory preclinical safety evaluation is an essential prerequisite to obtain the qualitative and effective medicines. Due to the fact that drugs may reveal genotoxic properties, the investigation of their mutagenic activity is an obligatory part of the preclinical drug safety program. The aim of the research is to study mutagenic properties of a new original immunomodulator Arglabin native in tablets in the induced test of gene mutations （the Ames test） on Salmonella typhimurium strains. Materials and methods： Four strains of S. typhimurium TA98, TA100, TA1535, and TA1537 were used to assess the mutagenicity in the Ames test. Results and conclusions： No statistically reliable dose-dependent increase in the number of revertant colonies of Salmonella typhimurium has been observed in the presence of the given drug within the investigated dose ranges from 5.0 to 100.0 μg/mL for strains TA100 and TA1535, and from 5.0 to 250 μg/mL for strains TA98 and TA1537 against the baseline of spantaneous mutations. Arglabin native in tablets does not reveal a mutagenic activity within the studied dose ranges on Salmonella typhimurium strains TA98, TA100, TA1535, TA1537.
