Antibacterial potency of methanol extracts of three green lower plants, Pneumatopteris afra, Platycerium bifurcatum and Nephrolepsis bisserata was determined using agar dilution method on clinical strains of Escherich...Antibacterial potency of methanol extracts of three green lower plants, Pneumatopteris afra, Platycerium bifurcatum and Nephrolepsis bisserata was determined using agar dilution method on clinical strains of Escherichia coli, Staphylococcus aureus, Klebsiella spp. and Salmomelia typhi. Antibacterial activities were observed at concentrations of 12.5, 25.0, 50.0 and 100.0 μg/ml. Their minimum inhibitory concentrations ranged from 12.5~100 μg/ml. Extracts of P. afra and P. bifurcatum were most active. Antibacterial activities observed with N. bisserata were less pronounced with no detectable activity at extract con-centrations of 12.5 and 25.0 μg/ml. E. coli, together with S. aureus appeared to be the most susceptible of the test bacteria while Klebsiella spp. was least sensitive. The significance of our findings is discussed.展开更多
Stable oxygen and hydrogen isotopic compositions （δ18O and δD） of soil water and shallow groundwater of a riparian forest, an artificial shrub forest, and Gobi of the lower reaches of the Heihe River Basin are use...Stable oxygen and hydrogen isotopic compositions （δ18O and δD） of soil water and shallow groundwater of a riparian forest, an artificial shrub forest, and Gobi of the lower reaches of the Heihe River Basin are used to study the recharge water sources of those ecosystems. IsoSource software is used to determine the δ180 values for root water of Populous euphratica and Tamarix ramosissima in the riparian forest ecosystem, Haloxylon ammodendron in the artificial shrub forest, and Reaumuria soongorica in the Gobi, as well as for local soil water and groundwater, and precipitation in the upper reaches of the Heihe River Basin. Our results showed that soil water and shallow groundwater of the riparian forest and the artificial shrub forest were recharged by river water which originated from precipitation in the upper reaches, and strong evaporation occurred in the artificial shrub forest. Soil water of the Gobi was not affected by Heihe River water due to this area being far away from the river channel. The main water sources of Populous euphratica were from 40-60-cm soil water and groundwater, and of Tamarix ramosissima were from 40-80-cm soil water in the riparian forest ecosystem. In the artificial forest, Haloxylon ammodendron used 200-cm saturated-layer soil water and shallow groundwater. The Reaumuria soongorica mainly used soil water from the 175-200-cm depth in the Gobi. Therefore, soil water and groundwater are the main water sources which maintain survival and growth of the plants in the extremely arid regions of the lower reaches of the Heihe River Basin.展开更多
整车制造业中,物流是非增值环节,物流成本的削减可以为企业赢取更高的边际利润。为了降低厂内生产物流成本,准时化生产(JIT,Just in Time),排序拉动生产(JIS,Just in Sequence),物流服务外包等模式应运而生。文章以北京奔驰后驱车工厂为...整车制造业中,物流是非增值环节,物流成本的削减可以为企业赢取更高的边际利润。为了降低厂内生产物流成本,准时化生产(JIT,Just in Time),排序拉动生产(JIS,Just in Sequence),物流服务外包等模式应运而生。文章以北京奔驰后驱车工厂为例,对厂内的生产物流作业成本进行研究。以零件进入车间为起点,以最小化厂内物流作业成本为目标,综合考虑实际生产约束,搭建收货、入库、出库和配线四大厂内物流作业成本优化模型并成功应用,既实现了本企业生产运营成本的节约,也为其他汽车企业的厂内物流成本优化提供借鉴思路。展开更多
Recently, whether Archaefructus has bisexual multi-parted flowers or just inflorescences of unisexual flowers, and whether it is ancestral to all angiosperms or a derived eudicot have been debated. Here, from the same...Recently, whether Archaefructus has bisexual multi-parted flowers or just inflorescences of unisexual flowers, and whether it is ancestral to all angiosperms or a derived eudicot have been debated. Here, from the same Yixian Formation, NE China, we report a new Archaefructus species, A. eoflora sp. nov., with the generic characteristics of dissected leaves and bisexual reproductive axes. It is entirely preserved with roots, rhizome, shoots and protogynous reproductive organs at different developmental stages. Its lateral and main fertile shoots form a pseudo-indeterminate pattern, while the reproductive branches on the main shoot form a cymose inflorescence. Subtended by 1-2 bract-like leaves, the section of stamen clusters changes into a much shorter section of carpels that have one row of orthotropous ovules. Significantly, one cluster bearing two carpels and one stamen between the two sections demonstrates a true bisexual flower, an important step of the origin of floral bisexuality, and the homology between the stamen and carpel. The complex reproductive axes represent a mix between flowers and inflorescences, and suggest that A. eoflora sp. nov. possesses the potential to evolve into a variety of diverse flower types as found in modern basal and early fossil angiosperms. A comparison with other two species also leads to a revision of the generic diagnosis.展开更多
This article focuses on the mathematical modelling of the extraction process of bioactive compounds from grape marc and berries (Aronia, rosehip, rowan, and hawthorn). The composition of the extraction medium (the con...This article focuses on the mathematical modelling of the extraction process of bioactive compounds from grape marc and berries (Aronia, rosehip, rowan, and hawthorn). The composition of the extraction medium (the concentration of the ethyl alcohol) served as a factor of influence. Furthermore, 8 experimental measured parameters were used as variables. The experimental results were processed using Hermite polynomials. In order to adapt the degree of the polynomial, the following conditions were imposed: high precision of the mathematical model by appealing to models on interval;obtaining a nominal model and two uncertain models (upper and lower);deduction of two predictive models, one superior and one inferior. It was found that the mathematical models based on Hermite polynomials do not provide explicit analytical expressions, although they allow the establishment of parameter values for any concentration of the extraction medium. In some cases, only high-grade polynomial models ensure the modelling error below 2%. Uncertain models (upper and lower 95%) include all experimental data. Predictive mathematical models (upper and lower) were established for a high prediction. The analytical expressions of the mathematical models on intervals are non-gaps, the coefficients having non-zero values. Dependencies between the measured parameters and the composition of the extraction solvent were analyzed, the results being presented through the calculation of a surface, with all the experimental values and their average values. Thus, it was found that polynomial mathematical models provide complete information for modelling the extraction processes of bioactive compounds of plant origin.展开更多
文摘Antibacterial potency of methanol extracts of three green lower plants, Pneumatopteris afra, Platycerium bifurcatum and Nephrolepsis bisserata was determined using agar dilution method on clinical strains of Escherichia coli, Staphylococcus aureus, Klebsiella spp. and Salmomelia typhi. Antibacterial activities were observed at concentrations of 12.5, 25.0, 50.0 and 100.0 μg/ml. Their minimum inhibitory concentrations ranged from 12.5~100 μg/ml. Extracts of P. afra and P. bifurcatum were most active. Antibacterial activities observed with N. bisserata were less pronounced with no detectable activity at extract con-centrations of 12.5 and 25.0 μg/ml. E. coli, together with S. aureus appeared to be the most susceptible of the test bacteria while Klebsiella spp. was least sensitive. The significance of our findings is discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91325102, 91025016 and 91125025)the National Science & Technology Support Project (No. 2011BAC07B05)
文摘Stable oxygen and hydrogen isotopic compositions （δ18O and δD） of soil water and shallow groundwater of a riparian forest, an artificial shrub forest, and Gobi of the lower reaches of the Heihe River Basin are used to study the recharge water sources of those ecosystems. IsoSource software is used to determine the δ180 values for root water of Populous euphratica and Tamarix ramosissima in the riparian forest ecosystem, Haloxylon ammodendron in the artificial shrub forest, and Reaumuria soongorica in the Gobi, as well as for local soil water and groundwater, and precipitation in the upper reaches of the Heihe River Basin. Our results showed that soil water and shallow groundwater of the riparian forest and the artificial shrub forest were recharged by river water which originated from precipitation in the upper reaches, and strong evaporation occurred in the artificial shrub forest. Soil water of the Gobi was not affected by Heihe River water due to this area being far away from the river channel. The main water sources of Populous euphratica were from 40-60-cm soil water and groundwater, and of Tamarix ramosissima were from 40-80-cm soil water in the riparian forest ecosystem. In the artificial forest, Haloxylon ammodendron used 200-cm saturated-layer soil water and shallow groundwater. The Reaumuria soongorica mainly used soil water from the 175-200-cm depth in the Gobi. Therefore, soil water and groundwater are the main water sources which maintain survival and growth of the plants in the extremely arid regions of the lower reaches of the Heihe River Basin.
文摘整车制造业中,物流是非增值环节,物流成本的削减可以为企业赢取更高的边际利润。为了降低厂内生产物流成本,准时化生产(JIT,Just in Time),排序拉动生产(JIS,Just in Sequence),物流服务外包等模式应运而生。文章以北京奔驰后驱车工厂为例,对厂内的生产物流作业成本进行研究。以零件进入车间为起点,以最小化厂内物流作业成本为目标,综合考虑实际生产约束,搭建收货、入库、出库和配线四大厂内物流作业成本优化模型并成功应用,既实现了本企业生产运营成本的节约,也为其他汽车企业的厂内物流成本优化提供借鉴思路。
文摘Recently, whether Archaefructus has bisexual multi-parted flowers or just inflorescences of unisexual flowers, and whether it is ancestral to all angiosperms or a derived eudicot have been debated. Here, from the same Yixian Formation, NE China, we report a new Archaefructus species, A. eoflora sp. nov., with the generic characteristics of dissected leaves and bisexual reproductive axes. It is entirely preserved with roots, rhizome, shoots and protogynous reproductive organs at different developmental stages. Its lateral and main fertile shoots form a pseudo-indeterminate pattern, while the reproductive branches on the main shoot form a cymose inflorescence. Subtended by 1-2 bract-like leaves, the section of stamen clusters changes into a much shorter section of carpels that have one row of orthotropous ovules. Significantly, one cluster bearing two carpels and one stamen between the two sections demonstrates a true bisexual flower, an important step of the origin of floral bisexuality, and the homology between the stamen and carpel. The complex reproductive axes represent a mix between flowers and inflorescences, and suggest that A. eoflora sp. nov. possesses the potential to evolve into a variety of diverse flower types as found in modern basal and early fossil angiosperms. A comparison with other two species also leads to a revision of the generic diagnosis.
文摘This article focuses on the mathematical modelling of the extraction process of bioactive compounds from grape marc and berries (Aronia, rosehip, rowan, and hawthorn). The composition of the extraction medium (the concentration of the ethyl alcohol) served as a factor of influence. Furthermore, 8 experimental measured parameters were used as variables. The experimental results were processed using Hermite polynomials. In order to adapt the degree of the polynomial, the following conditions were imposed: high precision of the mathematical model by appealing to models on interval;obtaining a nominal model and two uncertain models (upper and lower);deduction of two predictive models, one superior and one inferior. It was found that the mathematical models based on Hermite polynomials do not provide explicit analytical expressions, although they allow the establishment of parameter values for any concentration of the extraction medium. In some cases, only high-grade polynomial models ensure the modelling error below 2%. Uncertain models (upper and lower 95%) include all experimental data. Predictive mathematical models (upper and lower) were established for a high prediction. The analytical expressions of the mathematical models on intervals are non-gaps, the coefficients having non-zero values. Dependencies between the measured parameters and the composition of the extraction solvent were analyzed, the results being presented through the calculation of a surface, with all the experimental values and their average values. Thus, it was found that polynomial mathematical models provide complete information for modelling the extraction processes of bioactive compounds of plant origin.
