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111.
两种不同形貌FePO_4的制备及其正电极材料LiFePO_4的电化学性能 总被引:1,自引:0,他引:1
分别以Fe(NO_3)_3·9H_2O和FeSO_4·7H_2O为铁源,采用均相沉淀法和氧化-液相沉淀法制备了两种不同形貌的FePO_4粉体,再以FePO_4为前驱体,与LiOH·H_2O、蔗糖混合,采用碳热还原法合成了LiFePO_4正电极材料.用XRD和SEM对所制备的FePO_4粉体进行结构和表面形貌表征,测试了LiFePO_4样品的充放电性能.XRD和SEM测定结果表明,采用均相沉淀法制备的FePO_4为六方晶系纯相,颗粒形貌为圆片状,颗粒大小均匀;而液相氧化法制备的FePO_4也为六方晶系纯相,但颗粒形貌无规则.由圆片状FePO_4和无规则FePO_4所合成的LiFePO_4的颗粒形貌与其前驱体相同.充放电测试表明在0.5C下圆片状LiFePO_4的首次放电比容量为140 mAh/g,无规则LiFePO_4的首次放电比容量为89 mAh/g.经过50次循环后,前者的放电比容量仅下降1.43%,后者基本不变. 相似文献
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113.
Mark C. Hove Bernard E. Sietman Matthew S. Berg Erika C. Frost Kiru Wolf Tony R. Brady 《Journal of Natural History》2016,50(9-10):523-542
Managing a rare species can be improved with knowledge of its natural history. The sheepnose (Plethobasus cyphyus) is a freshwater mussel recently listed by the US as federally endangered. We used standard methods to study P. cyphyus brooding behaviour, host fishes in the laboratory and under natural conditions, and glochidial morphology. We monitored a population of P. cyphyus in the Chippewa River, WI during spring and summer 2007–2009 and 2011 and found brooding animals between mid-May and early August. Gravid individuals ranged between 5 and 27 yr (mean age ± 1 s.d. = 13 ± 4 yr). Plethobasus cyphyus brooded glochidia in outer gills, which varied in colour from red, orange, pink, cream, or white. We observed mature glochidia more commonly in individuals with cream or white gills and these glochidia were released in a clear, adhesive, mucus matrix. In laboratory trials we found several minnow and topminnow species (29 spp.) served as productive suitable native hosts. The mean number of juvenile mussels released per cyprinid per day was significantly higher for trials conducted at 22–25°C compared with those at 18–20°C, and 83% of trials conducted at 18–20°C using suitable host species produced no juveniles. Glochidia had a unique outline and shell morphometrics that distinguished P. cyphyus from seven other Chippewa River mussel species that produce similar sized glochidia. Using morphometrics we determined that mimic shiners (Notropis volucellus) were natural hosts for P. cyphyus, round pigtoe (Pleurobema sintoxia), and Wabash pigtoe (Fusconaia flava). Releasing mucus-bound glochidia has evolved in a variety of mussel species and may be more common than is currently realized. Our data show that P. cyphyus is a cyprinid host specialist, and propagation efforts for this species can be strengthened through improved access to mature glochidia by using females with cream-coloured gills and increased juvenile production through warmer fish holding temperatures. 相似文献
114.
《Journal of Natural History》2012,46(41-42):2519-2535
Most species of the Old World pseudoscorpion genus Megachernes are associated with mammals, either within their nests or in their pelage, whereas others are found in cave systems, usually in bat guano. The first Sri Lankan species of the genus, Megachernes kanneliyensis, is described from the fur of an endemic, threatened Sri Lankan mouse, Mus mayori pococki from the Kanneliya rainforest. The species is compared with other species of the genus. Host associations of all named and several unnamed species of Megachernes are reviewed, with two main habitat types, those found in mammal nests and in their pelage, and those found in bat guano. Based on similarities with Megachernes, Chiridiochernes is transferred to Lamprochernetinae as the spermathecae are T-shaped, the sole diagnostic feature of the subfamily. 相似文献
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116.
《Journal of Natural History》2012,46(43-44):2581-2595
The carpenter moth Eogystia sibirica (Alphéraky) (Lepidoptera: Cossidae) is a serious pest of the garden asparagus Asparagus officinalis (family Liliaceae) in northern China, with its larvae boring in the stem and roots, frequently causing significant damage to the plant. All the life stages of the pest, including egg, larva, pupa and adult, are described and illustrated in detail. The ovoid egg is covered with a reticulate meshwork of ridges on the chorion. The eruciform larva possesses only three stemmata on each side of the head; the reduced abdominal prolegs on segments III–VI each bear 35–55 uniordinal crochets arranged in two transverse bands; the short anal prolegs each bear five to seven uniordinal crochets in a transverse band. The pupa is adecticous and obtect, without cremaster. The reduction of larval stemmata and the invagination of the adult pterosterna are briefly discussed. 相似文献
117.
《Journal of Natural History》2012,46(11):819-834
Three cryptic species of the genus Munida from New Caledonia, previously identified as M. tuberculata Henderson, , M. notata Macpherson, and M. clinata Macpherson, , are described and illustrated. The three species are identified by subtle and constant morphological characters, which match clear differences in molecular sequences (16S rDNA and COI genes). The results also confirm the importance of several of these characters (e.g. length of the antennular and antennal spines) in the taxonomy of the genus Munida. 相似文献
118.
The effect of Si on the austenite stabilization, martensite morphology, and magnetic properties in Fe-26%Ni-x%Si (x=3.5, 5, and 6) alloys have been studied by means of transmission electron microscopy (TEM) and M?ssbauer spectroscopy techniques. TEM observations reveal that the martensite morphology is closely dependent on the Si content. The volume fraction changes of martensite and austenite phases, the hyperfine magnetic field, and isomer shift values have been determined by Mssbauer spectroscopy. The M?ssbauer study reveals that the hyperfine magnetic field, the isomer shift values and the volume fraction of martensite decrease with increasing Si content. 相似文献
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120.
《Journal of Natural History》2012,46(40):3501-3524
The ant Acropyga sauteri Forel has an obligate, mutualistic symbiosis with a mealybug, Eumyrmococcus smithii Silvestri, on Okinawa Island, southern Japan. The mealybugs live inside ant nests nearly all their lives, and the ants depend on them for food. Alate foundress queens carry mealybugs during their nuptial flights, using them to establish new colonies at new sites. However, important aspects of the symbiosis have not yet been elucidated. The present study characterizes the basic biology of the symbiosis and describes for the first time the morphologies of all growth stages of E. smithii. Our study suggests that E. smithii has only one nymphal stage, followed by a female pupal stage or male prepupal stage. Intensive sampling of ant nests across seasons showed that A. sauteri prefers nest sites 5–20 cm underground. Acropyga sauteri produced reproductive stages mainly in mid‐March or early April, and numbers of both ant workers and mealybugs increased from spring to summer. Experimental determination of colony identity with a method using nestmate recognition by ants suggested that each ant colony rarely has a perimeter greater than 30 cm, that the ants are monogynous, and that different ant colonies are densely aggregated along the root system of a plant, adjacent to each other but not interflowing. Both symbiotic partners were vulnerable to attacks by several common subaerial ant species following physical disturbance to their nests. 相似文献