Abstract: Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition. Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under condi...Abstract: Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition. Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under conditions of low phosphorus availability, the length of cells in the meristem zone of the lateral roots was longer, but the length of cells in the elongation and mature zones of the lateral roots was shorter, compared with seedlings grown under conditions of high phosphorus availability. The elongation rates of primary roots increased as phosphorus availability increased, but the elongation rates of the branched zones of the primary roots decreased. The number of lateral root primordia and the length of the lateral roots decreased as phosphorus availability increased. The topological index (altitude slope) decreased as phosphorus availability increased, suggesting that root architecture tended to be herringbone-like when seedlings were grown under conditions of low phosphate availability. Herringbone-like root systems exploit nutrients more efficiently, but they have higher construction costs than root systems with a branching pattern.展开更多
Two typical and important copper-containing enzymes, laccase (Lac) and tyrosinase (Tyr), have been im- mobilized on the surface of active carbon with simple ad- sorption method. The cyclic voltammetric results indicat...Two typical and important copper-containing enzymes, laccase (Lac) and tyrosinase (Tyr), have been im- mobilized on the surface of active carbon with simple ad- sorption method. The cyclic voltammetric results indicated that the active carbon could promote the direct electron transfer of both Lac and Tyr and a pair of well-defined and nearly symmetric redox peaks appeared on the cyclic volt- ammograms of Lac or Tyr with the formal potential, E0′, independent on the scan rate. The further experimental re- sults showed that the immobilized copper-containing oxidase displayed an excellent electrocatalytic activity to the electro- chemical reduction of O2. The immobilization method pre- sented here has several advantages, such as simplicity, easy to operation and keeping good activity of enzyme etc., and could be further used to study the direct electrochemistry of other redox proteins and enzymes and fabricate the catalysts for biofuel cell.展开更多
In this paper, by virtue of the combinatorial optimization and group testing method and, with a scale without weight, we detect n coins containing at most one abnormal.The n coins are indistinguishable only by their a...In this paper, by virtue of the combinatorial optimization and group testing method and, with a scale without weight, we detect n coins containing at most one abnormal.The n coins are indistinguishable only by their appearances. We derive an optimal procedure of determining whether all the n balls are normal or not and in the latter case, our procedure (algorithm) also tells whether the abnormal weighs more or weighs less than each of the normals. The optimal algorithm obtained in this paper is constructive.展开更多
文摘Abstract: Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition. Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under conditions of low phosphorus availability, the length of cells in the meristem zone of the lateral roots was longer, but the length of cells in the elongation and mature zones of the lateral roots was shorter, compared with seedlings grown under conditions of high phosphorus availability. The elongation rates of primary roots increased as phosphorus availability increased, but the elongation rates of the branched zones of the primary roots decreased. The number of lateral root primordia and the length of the lateral roots decreased as phosphorus availability increased. The topological index (altitude slope) decreased as phosphorus availability increased, suggesting that root architecture tended to be herringbone-like when seedlings were grown under conditions of low phosphate availability. Herringbone-like root systems exploit nutrients more efficiently, but they have higher construction costs than root systems with a branching pattern.
文摘Two typical and important copper-containing enzymes, laccase (Lac) and tyrosinase (Tyr), have been im- mobilized on the surface of active carbon with simple ad- sorption method. The cyclic voltammetric results indicated that the active carbon could promote the direct electron transfer of both Lac and Tyr and a pair of well-defined and nearly symmetric redox peaks appeared on the cyclic volt- ammograms of Lac or Tyr with the formal potential, E0′, independent on the scan rate. The further experimental re- sults showed that the immobilized copper-containing oxidase displayed an excellent electrocatalytic activity to the electro- chemical reduction of O2. The immobilization method pre- sented here has several advantages, such as simplicity, easy to operation and keeping good activity of enzyme etc., and could be further used to study the direct electrochemistry of other redox proteins and enzymes and fabricate the catalysts for biofuel cell.
文摘In this paper, by virtue of the combinatorial optimization and group testing method and, with a scale without weight, we detect n coins containing at most one abnormal.The n coins are indistinguishable only by their appearances. We derive an optimal procedure of determining whether all the n balls are normal or not and in the latter case, our procedure (algorithm) also tells whether the abnormal weighs more or weighs less than each of the normals. The optimal algorithm obtained in this paper is constructive.
