What Do We Know About Metal Recycling Rates?

The recycling of metals is widely viewed as a fruitful sustainability strategy, but little information is available on the degree to which recycling is actually taking place. This article provides an overview on the current knowledge of recycling rates for 60 metals. We propose various recycling metrics, discuss relevant aspects of recycling processes, and present current estimates on global end‐of‐life recycling rates (EOL‐RR; i.e., the percentage of a metal in discards that is actually recycled), recycled content (RC), and old scrap ratios (OSRs; i.e., the share of old scrap in the total scrap flow). Because of increases in metal use over time and long metal in‐use lifetimes, many RC values are low and will remain so for the foreseeable future. Because of relatively low efficiencies in the collection and processing of most discarded products, inherent limitations in recycling processes, and the fact that primary material is often relatively abundant and low‐cost (which thereby keeps down the price of scrap), many EOL‐RRs are very low: Only for 18 metals (silver, aluminum, gold, cobalt, chromium, copper, iron, manganese, niobium, nickel, lead, palladium, platinum, rhenium, rhodium, tin, titanium, and zinc) is the EOL‐RR above 50% at present. Only for niobium, lead, and ruthenium is the RC above 50%, although 16 metals are in the 25% to 50% range. Thirteen metals have an OSR greater than 50%. These estimates may be used in considerations of whether recycling efficiencies can be improved; which metric could best encourage improved effectiveness in recycling; and an improved understanding of the dependence of recycling on economics, technology, and other factors.     

大鼠离体乳头肌收缩末期张力—长度关系的曲线性

大鼠离体左室乳头肌固定于最适初长位,逐步递减“后荷”获得一系列等张收缩的张力、长度缩短程度和速度。结果发现:(1)收缩末期张力-长度关系(ESTLR)为指数曲线,回归方程 T=ar~(-bL)-K 拟合的优度明显高于线性方程拟合的优度(P<0.001),其中 a,k 分别代表总张力和静息张力,b 为曲线的弯曲度;(2)在高钙(4mmol/L)或去甲肾上腺素(NE10~(-6)mol/L)作用下,ESTLR 右上移位,a,b 和无张力缩短速度 L_O 均增大(P均<0.01),尤以高钙时的变化更明显,(3)NE 使张力-速度曲线的右上移位比高钙显著。这提示大鼠离体心肌的 ESTLR 呈非线性特征,参数 a,b 及长度轴截距 L_O 对收缩强度的变化敏感,但对收缩速度改变的敏感性可能比经典的力学指标低。     

Ultrastructure of Phasmid Development in Meloidodera floridensis and M. charis (Heteroderinae)

Phylogenetic characters for Heteroderinae Luc. et al., 1988 are evaluated in Meloidodera which is believed to have primarily ancestral characters. Phasmid ultrastructure is observed in second-stage juveniles (J2), third-stage juvenile males, fourth-stage juvenile males, and fifth-stage males of Meloidodera floridensis and M. charis. Phasmid secretion occurs inside the egg before the J1-J2 molt. Before J2 hatch, concentric lamellar membranes occur within the sheath and socket cells. Some membranes become lamellae of the sheath cell plasma membrane; others become multilamellar bodies. During early molting, plasma membrane lamellae disappear and a distal dendrite segment appears in a rudimentary canal. After the molt, the distal dendrite is not present within the canal. The phylogenetic utility of phasmid features is discussed. In both species the ampulla shape and size between molts are stable features in juveniles and males. The posthatch J2 sheath cell receptor cavity may vary in a species specific manner, but comparative morphology requires precise timing after hatch.     

Sequence analysis of cohesive ends of the actinophage RP3 genome and construction of a transducible shuttle vector

Abstract The sequence of the cohesive ends of actinophage RP3 DNA has been determined. As with all other phages of Gram-positive bacteria that have been studied sofar, RP3 DNA has 3'-protruding ends. A shuttle cosmid has been constructed containing this cos area which can be efficiently transduced by phage RP3 to host cells of Streptomyces rimosus .     

用平截末端使大豆根瘤菌苹果酸脱氨酶基因插入失活及电激法转化

本实验用平截末端连接法把卡那霉素抗性基因插入到大豆根瘤菌（Ｂｒａｈｙｒｈ;ｚｏｂｉｕｍｊａｐｏｎｉｃｕｍ）１１０的苹果酸脱氢酶（ｍｄｈ）基因中,致使ｍｄｈ基因失活,再通过电激法把这一重组基因转入大豆根瘤菌（Ｂｒａｈｙｒｈｉｚｏｂｉｕｍｊａｐｏｎｉｃｕｍ）２１４３中,进而探讨ｍｄｈ基因失活对大豆固氮作用的影响。     

基于结构比较的蛋白质同源模建系统及其评估Ⅱ侧链的安装

至今,有关蛋白质侧链的同源模建,除了在本体模板上安装侧链和少数限制条件下在同源模板上安装侧链的报道外,系统的研究和实施似乎还未见报道。本软件系统ＰＭＯＤＥＬＩＮＧ采用同源移植和“死端排除“相结合的侧链安装策略,对与模板蛋白相应践基具有相似大小和形状的目标残基采用直接移植的方法。其余铡链则用广义“死端排除定则”安装。经众多蛋白的测试,达到了较好的模建品质。     

Assessment of a model for intron RNA secondary structure relevant to RNA self-splicing--a review

A widespread class of introns is characterized by a particular RNA secondary structure, based upon four conserved nucleotide sequences. Among such "class I" introns are found the majority of introns in fungal mitochondrial genes and the self-splicing intron of the large ribosomal RNA of several species of Tetrahymena. A model of the RNA secondary structure, which must underlie the self-splicing activity, is here evaluated in the light of data on 16 further introns. The main body or "core structure" of the intron always consists of the base-paired regions P3 to P9 with the associated single-stranded loops, with P2 present also in most cases. Two minority sub-classes of core structure occur, one of which is typical of introns in fungal ribosomal RNA. Introns in which the core structure is close to the 5' splice site all have an internal guide sequence (IGS) which can pair with exon sequences adjacent to the 5' and 3' splice sites to align them precisely, as proposed by Davies et al. [Nature 300 (1982) 719-724]. In these cases, the internal guide model allows us to predict correctly the exact location of splice sites. All other introns probably use other mechanisms of alignment. This analysis provides strong support for the RNA splicing model which we have developed.     

Packaging of coliphage lambda DNA. I. The role of the cohesive end site and the gene A protein

The cohesive ends of the DNA of bacteriophage λ particles are normally formed by the action of a nuclease on the cohesive end sites (cos) of concatemeric λ DNA (reviewed by Hohn et al., 1977). The nuclease also cuts the cos site of an integrated prophage, and DNA located to the right is preferentially packaged into phage particles. This process occurs with approximately the same efficiency and rate in a single lysogen as in a tandem polylysogen. Thus, the rate of cos cutting does not increase when the number of cos sites per molecule increases, an hypothesis that has been proposed to explain why cohesive ends are not formed in circular monomers of λ DNA. We propose instead that the interaction of Ter with cos is influenced by the configuration of the DNA outside of cos during packaging, and that this configuration is different for circular monomers than for other forms of λ DNA. A model that gives rise to such a difference is described.We also found that missense mutations in the λ A gene changed the efficiency of packaging of phage relative to host DNA. This was not the case for missense mutations in several phage genes required for capsid formation. Thus, the product of gene A plays a role in determining packaging specificity, as expected if it is or is part of the nuclease that cuts λ DNA at cos.     

Conversion of Tyrosine Hydroxylase to Stable and Inactive Form by the End Products

We have reported previously that tyrosine hydroxylase in the crude extract from rat striatum exists in the inactive form showing almost no activity at the physiological pH and that the inactive form is produced by the action of the end products of the enzyme, such as dopamine. The incubation of the enzyme with the end products resulted in not only the inactivation but also a remarkable stabilization of the enzyme. Catechols possessing amino groups but no negatively charged groups on the side chains (catecholamine-type catechols) were effective at a concentration as low as 10(-7) M in both the inactivation and stabilization of the enzyme. In contrast, catechols not possessing positively or negatively charged side chains (3,4-dihydroxyphenylethyleneglycol-type catechols) were ineffective at a concentration of 10(-7) M but effective at a concentration of 10(-6) M for both the inactivation and stabilization. Catechols possessing negatively charged groups (3,4-dihydroxyphenylacetic acid-type catechols) were ineffective even at a concentration of 10(-6) M. Thus, the end products of tyrosine hydroxylase appear to serve to keep the enzyme inactive and stable. The reaction mechanism of the conversion of the enzyme from the active/labile form to the inactive/stable form by dopamine was also investigated.