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1. chinaXiv:201708.00223 [pdf]

Laser irradiation-induced Au-ZnO nanospheres with enhanced sensitivity and stability in ethanol sensing

分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Incorporating noble metal nanoparticles on the surface or inner side of semiconductors to form a hybrid nanostructure is an effective route to improve the gas sensing performance of these semiconductors. In this study, we present novel Au-decorated ZnO nanospheres (Au-ZnO NSs) obtained by laser irradiation of liquids. Structural characterization indicated that the Au-ZnO NSs consisted of single crystalline ZnO NSs with few Au nanoparticles decorated on their surfaces and abundant encapsulated Au nanoparticles with relatively small sizes. Laser irradiation-induced heating–melting–evaporating processes are responsible for the formation of unique Au-ZnO NSs. Gas sensing properties of the Au-ZnO NSs, as gas sensing materials, were investigated and compared with those of pure ZnO NSs. The former showed lower working temperature, higher sensitivity, better selectivity, and good reproducibility. The response values of Au-ZnO NSs and pure ZnO NSs sensors to ethanol of 100 ppm were 252 and 75 at working temperature of 320 °C and 360 °C, respectively. The significant enhancements in gas sensing performance should be attributed to the electronic sensitization induced by the depleted layers between encapsulated Au nanoparticles and ZnO and chemical sensitization originating from the catalytic effects of Au nanoparticles decorated on the surfaces that dissociated molecular oxygen.

提交时间: 2017年08月18日 点击量:32, 下载量:21

2. chinaXiv:201708.00218 [pdf]


陈皓勇; 韩励佳
分类: 动力与电气工程 >> 电气工程


提交时间: 2017年08月16日 点击量:895, 下载量:226

3. chinaXiv:201708.00219 [pdf]

Monodispersed Carbon Nanodots Spontaneously Separated from Combustion Soot with Excitation.pdf

分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

We present a facile, low-cost procedure by simple one-step combustion of small organic molecules to obtain ultrafine, hydrophobic, and fluorescent carbon nanodots (CNDs). Without further centrifugation and dialysis, we could easily separate CNDs from combustion soot through spontaneous sedimentation. Transmission electron microscopy and photoluminescence characterization demonstrated that the collected CNDs possessed a monodispersed size distribution with a diameter of 1.9 ± 0.5 nm and excitation-independent luminescent properties. Furthermore, after oxidization treatment, the oxidized CNDs displayed good water solubility and the highest fluorescent intensity at neutral solution.

提交时间: 2017年08月16日 点击量:45, 下载量:30

4. chinaXiv:201708.00217 [pdf]

Photo-excited in situ loading of Pt clusters onto rGO immobilized SnO2 with excellent catalytic performance toward methanol oxidation

分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Great effort is made to maximize the surface area and expose active sites of a catalyst by distributing it over a suitable electronic conducting support. We present a design and eco-friendly construction of a two-dimensional Pt/SnO2/reduced-graphene-oxide (rGO) nanocomposite to study the strong metal-semiconductor-support interactions as candidate highly active and durable electrocatalyst. Distinctively, highly reactive SnOx nanoparticles (NPs) induced by laser ablation in liquids were used as a precursor to transform the graphene oxide (GO). Simultaneously, the initial amorphous-like SnOx further crystallized into SnO2 NPs, which were uniformly anchored onto rGO sheets. Afterward, the photo-excited electrons from semiconductor SnO2 were used as green reducing agents. Ultrafine Pt NPs with an average size of about 1–2 nm were in situ reduced and uniformly anchored on the surface of crystallized SnO2 NPs. Compared with the Pt/rGO catalysts without SnO2 modification, the prepared Pt/SnO2/rGO catalysts not only show larger electrochemical active surface area and higher catalytic activity toward methanol oxidation but also exhibit better tolerance toward CO and long-term cycle stability. The significantly enhanced electrochemical performance should be attributed to the uniformly dispersed Pt NPs with ultrafine size and the synergetic effect from the hybrid noble metal-semiconductor-carbon network components, which possess promising potential applications as electrocatalysts for methanol oxidation.

提交时间: 2017年08月15日 点击量:46, 下载量:31

5. chinaXiv:201703.00903 [pdf]

Preparation and electrochemical properties of high purity mixed-acid electrolytes for high energy density vanadium redox flow battery

Fan, Chuanlin; Yang, Haitao; Zhu, Qingshan
分类: 材料科学 >> 材料化学

All-vanadium redox flow battery (VRFB) is a large-scale electrochemical energy storage technology with numerous potential applications because of its inherent safety and long service life. In previous years, a novel mixed-acid electrolyte system, vanadium electrolytes with mixture of sulfuric acid and hydrochloric acid, has been developed by the Pacific Northwest National Laboratory (PNNL) to increase vanadium solubility, which can effectively raise the electrolyte energy density from 25 Wh/L to 40 Wh/L. To further improve mixed-acid VRFBs, in present work, high purity mixed-acid electrolytes were prepared using a novel direct dissolution – electrochemical reduction process from high purity vanadium oxytrichloride (VOCl3). And the purity and electrochemical properties were investigated, comparing with common mixed-acid electrolytes and regular sulfate electrolytes prepared from metallurgical grade vanadium pentoxide. It was found that the novel process demonstrated a great potential for the low cost and high efficiency production of high purity electrolytes with excellent electrochemical properties for mixed-acid VRFBs. Comparing the traditional high purity electrolytes preparation process, the present novel method will dramatically cut the cost by more than 90 percent, which will considerably facilitate the commercial application of high performance and high density VRFBs.

提交时间: 2017年08月15日 点击量:315, 下载量:242

6. chinaXiv:201708.00216 [pdf]


刘静羽; 黄金霞; 王昉
分类: 图书馆学、情报学 >> 图书馆学


提交时间: 2017年08月15日 点击量:52, 下载量:47

7. chinaXiv:201708.00210 [pdf]

The frst discovery of Urmiatherium (Bovidae, Artiodactyla) from Liushu Formation, Linxia Basin

SHI Qin-Qin; WANG Shi-Qi; CHEN Shao-Kun; LI Yi-Kun
分类: 地球科学 >> 地质学

A new skull of Urmiatherium intermedium (Bovidae, Artiodactyla) from the Linxia Basin, Gansu Province is described here. U. intermedium is a large Late Miocene bovid with an odd-looking horn apparatus, consisting of a pair of degenerate, closely situated horn-cores, and a large area of exostoses on the frontal and the parietal bones. Plenty of skulls, teeth, and bone fragments of U. intermedium have been reported from North China, but the skull to be described is the first discovery from the Linxia Basin, expanding the geographic distribution of U. intermedium to the northeast edge of the Tibetan Plateau. Although Urmiatherium is generally thought to be closely related to Plesiaddax, Hezhengia, Tsaidamotherium, and some other Late Miocene “ovibovines”, the phylogenetic position of Urmiatherium is still in debate. The distribution of Urmiatherium is wide, spanning from Iran to North China. Urmiatherium seldom accompanies with other Late Miocene “ovibovines” in North China, but is accompanied by other bovids like Sinotragus. 报道并描述了一件来自甘肃临夏盆地的中间乌米兽(Urmiatherium intermedium)头骨化石新材料,该材料产自柳树组上部,属于晚中新世晚期杨家山动物群。中间乌米兽是一种大型的晚中新世牛科动物,角心特化,短且呈薄板状,并且在基部相互靠近。在角心前后方的额骨和顶骨上,发育大片赘生骨疣,这些骨疣与角心一起,合称角器。20世纪初,步林报道了中国北方晚中新世地层中的大量中间乌米兽化石,包括产自山西保德和甘肃庆阳的二十多件头骨以及很多破碎的齿列和骨骼。本文报道的乌米兽头骨化石是乌米兽在甘肃临夏盆地的首次发现,将其在中国北方的分布向西扩展到了青藏高原东北缘地带。乌米兽被普遍认为与近旋角羊(Plesiaddax)、和政羊(Hezhengia)和柴达木兽(Tsaidamotherium)等晚中新世“麝牛类”牛科动物具有较近的亲缘关系,但其系统发育地位仍存有争议。相比其他晚中新世“麝牛类”牛科动物,乌米兽的分布较广,从伊朗至中国北方都有分布,但它鲜与其他晚中新世“麝牛类”牛科动物伴生。在临夏盆地,与其伴生的牛科动物目前仅发现中华羚(Sinotragus)一种。

提交时间: 2017年08月11日 来自合作期刊:《古脊椎动物学报》 点击量:81, 下载量:53

8. chinaXiv:201708.00208 [pdf]

Sciurid remains from the Late Cenozoic fssure-fllings of Fanchang, Anhui, China

QIU Zhu-Ding; JIN Chang-Zhu
分类: 地球科学 >> 地质学

Remains of sciurids from a late Cenozoic fissure in Anhui, China are described. Six taxa, including one new genus and two new species, representing five genera and four tribes in the subfamily Sciurinae are recognized. They are Sciurus sp., Tamias sp., Plesiosciurus zhengi sp. nov., Sciurotamias wangi Qiu, 2002, S. teilhardi Zheng, 1993, and Pseudoratufa wanensis gen. et sp. nov. The material described was collected from four levels of the fissure fillings. On the basis of the fossil content and coloration, the collection is considered to be a mixed sample with elements representing a rather long interval, probably ranging from the Early Miocene to the Pleistocene. The assemblage shows similar traits of the late Cenozoic sciurine faunas from central and southern China, and contains an intriguing genus Pseudoratufa. Characters of the latter’s dentition clearly demonstrate that the new-comer of ratufin is a tree squirrel; Pseudoratufa is probably coeval with the Fanchang hominoid, and with Diatomys and beavers found in this fissure. The joint occurrence of these taxa seems to be indicative of existence of forest biotopes once in this district during the earlier Miocene. 描述了安徽繁昌癞痢山塘口晚新生代裂隙堆积物中发现的松鼠类材料。化石代表松鼠亚科的4个族,共有5属6种,其中包括一个新属和两个新种,即树松鼠族的Sciurus sp., 花鼠族的Tamias sp.和Plesiosciurus zhengi sp. nov., 旱獭族的Sciurotamias wangi Qiu, 2002和S. teilhardi Zheng, 1993, 以及巨松鼠族的Pseudoratufa wanensis gen. et sp. nov.。所研究的材料系混合地采自同一裂隙堆积的4个不同层位,化石的组分可能代表从早中新世至更新世的不同时段。繁昌的这一松鼠组合具有中国中南部晚新生代松鼠动物群的特色,并含有稀奇的Pseudoratufa属。该新属的牙齿形态显示了其树栖松鼠的特征,而且可以归入甚为稀有的巨松鼠族。其遗骸具有与该地点发现的古猿、硅藻鼠和河狸类化石相似的石化和堆积过程,似乎表明这些动物属于时代相同或较接近的群体,它们的共存也说明了繁昌地区在中新世时有过相对湿润的森林生境。

提交时间: 2017年08月11日 来自合作期刊:《古脊椎动物学报》 点击量:79, 下载量:58

9. chinaXiv:201708.00206 [pdf]

New materials of micromammal fossils from Longyadong Cave in Luonan Basin, Shaanxi, central China

LI Yong-Xiang; HU Song-Mei; WANG She-Jiang; ZHANG Yun-Xiang
分类: 地球科学 >> 地质学

This paper describes some micromammal fossils which were excavated from the South Longyadong Cave in the Luonan Basin, eastern Qinling Mountains of Shaanxi Province, central China. The fauna include 15 mammals consisting by Scapanulus oweni, Nasillus andersoni, Uropsilinae gen. et sp. indet., Soriculus sp., Ochotona cf. O. alpina, Belomys parapearsoni, Allocricetus ehiki, Proedromys bedfordi, Allophaiomys deucalion, Eospalax sp., Niviventer preconfucianus, Apodemus asianicus, Apodemus sp., Hystrix brachyura subcristata, Trogontherium cuvieri. Among them, the Nasillus andersoni and the Ochotona cf. O. alpina are the newly discovered fossil species. The fossil assemblage characteristics of newly micromammal faunal is similar to the North Longyadong Cave Fauna, and the geological age should not be later than early Middle Pleistocene. It might be a fauna of late Early Pleistocene. But in recent years, the thermoluminescence age of fossiliferous strata corresponding are 356.6±17.8 kaBP, 273.9±13.7 kaBP and 210.5±10.5 kaBP. The fauna is including both the south and the north animals, the animal combination obviously has the characteristics of the transition between the south and the north of China. 描述了1995~1997年东秦岭山地洛南盆地龙牙南洞洞穴遗址中发掘出土的小哺乳动物化石,包括甘肃鼹Scapanulus oweni, 峨眉鼩鼹Nasillus andersoni, 鼩鼹(属种未定) Uropsilinae gen. et sp. indet., 长尾鼩鼱Soriculus sp., 似高山鼠兔Ochotona cf. O. alpina, 偏皮氏毛耳飞鼠Belomys parapearsoni, 艾克氏异仓鼠Allocricetus ehiki, 沟牙田鼠Proedromys bedfordi, 欧洲异费鼠Allophaiomys deucalion, 始鼢鼠Eospalax sp., 先社鼠Niviventer preconfucianus, 亚洲姬鼠Apodemus asianicus, 姬鼠Apodemus sp., 马来豪猪(华南亚种) Hystrix brachyura subcristata, 居氏大河狸Trogontherium cuvieri等。该动物群同时包括南方型和北方型动物,其动物组合具有明显的南北过渡地带的特征。其中峨眉鼩鼹和似高山鼠兔为新发现的化石种。新发现的小哺乳动物化石组合类似于龙牙北洞,显示出比较古老的性质,时代上多为早更新世晚期或中更新世早期,但龙牙南洞遗址含化石地层对应的热释光(TL)年龄结果分别为(356.6±7.8) kaBP, (273.9±3.7) kaBP和(210.5±0.5) kaBP, 最近新的回授光释光(TT-OSL)测年数据进一步验证了热释光测年结果,获得的地层年代亦为距今40~20万年左右。

提交时间: 2017年08月11日 来自合作期刊:《古脊椎动物学报》 点击量:116, 下载量:72

10. chinaXiv:201708.00205 [pdf]

A skull of Machairodus horribilis and new evidence for gigantism as a mode of mosaic evolution in machairodonts (Felidae, Carnivora)

DENG Tao; ZHANG Yun-Xiang; Zhijie J. TSENG; HOU Su-Kuan
分类: 地球科学 >> 地质学

Sabertooth cats were extinct carnivorans that have attracted great attention and controversy because of their unique dental morphology representing an entirely extinct mode of feeding specialization. Some of them are lion-sized or tiger-sized carnivorans who are widely interpreted as hunters of larger and more powerful preys than those of their modern nonsaber-toothed relatives. We report the discovery of a large sabertooth cat skull of Machairodus horribilis from the Late Miocene of northwestern China. It shares some characteristics with derived sabertooth cats, but also is similar to extant pantherines in some cranial characters. A functional morphological analysis suggests that it differed from most other machairodont felids and had a limited gape to hunt smaller preys. Its anatomical features provide new evidence for the diversity of killing bites even within in the largest saber-toothed carnivorans and offer an additional mechanism for the mosaic evolution leading to functional and morphological diversity in sabertooth cats. 剑齿虎是一类绝灭的食肉目动物,由于其独特的牙齿形态代表了已完全消失的特化取食方式而引起了极大的关注和争论。一些剑齿虎是狮子体型或老虎体型的食肉动物,它们被广泛认为能够比其不具剑形犬齿的现代近亲捕杀更大和更强壮的猎物。本文报道在甘肃省晚中新世地层中发现的一具属于恐剑齿虎(Machairodus horribilis)的大型头骨。这件标本的一些特征与进步的剑齿虎相同,但在某些头骨性状上则与现生的豹亚科种类相似。不同于其他大多数剑齿虎,功能形态分析指示该剑齿虎的口部张开程度受到限制,因此只能捕猎相对较小的猎物。这具头骨的解剖特征为证明即使在最大的具剑形犬齿的食肉目动物中也存在捕猎咬杀方式的多样性提供了新的证据,并揭示了在剑齿虎中导致功能和形态多样性镶嵌进化的另一种机制。

提交时间: 2017年08月11日 来自合作期刊:《古脊椎动物学报》 点击量:112, 下载量:70

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