34,040 research outputs found
Yaothrips as a new synonym of Pezothrips, with description of the male of Pezothrips pediculae comb.n. (Thysanoptera: Thripidae)
No full textTong, Xiaoli, Liu, Liangxin (2019): Yaothrips as a new synonym of Pezothrips, with description of the male of Pezothrips pediculae comb.n. (Thysanoptera: Thripidae). Zootaxa 4646 (3): 598-600, DOI: 10.11646/zootaxa.4646.3.1
A new record and mitochondrial identification of Synidotea laticauda Benedict, 1897 (Crustacea: Isopoda: Valvifera: Idoteidae) from the Yangtze Estuary, China
No full textLiu, Wenliang, Liang, Xiaoli, Zhu, Xiaojing (2017): A new record and mitochondrial identification of Synidotea laticauda Benedict, 1897 (Crustacea: Isopoda: Valvifera: Idoteidae) from the Yangtze Estuary, China. Zootaxa 4294 (3): 371-380, DOI: https://doi.org/10.11646/zootaxa.4294.3.
Theoretical Comparison of Test Performance of Different Pulse Decay Methods for Unconventional Cores
No full textVarious pulse decay methods are proposed to test tight cores. These methods can be divided into three types. This study compares the performance of these methods to test the permeability of unconventional cores in terms of homogeneous cores, dual-medium cores, and gas adsorption, including the pressure equilibrium time, possible errors caused by conventional analysis methods, and reflections on the characteristics of dual-media. Studies shows that the two test methods with an antisymmetric relationship in the boundary conditions have basically identical test performance. When testing homogeneous cores, regardless of whether the gas is adsorptive or not, the pressure equilibrium time of the first type of method is approximately half of that of the second type of method. The dual-medium parameters seriously affect the pressure equilibrium time of different methods, which may cause the difference of order of magnitude. For homogeneous cores, the permeability errors of the first and second types of methods caused by porosity errors are similar and larger than that of the third type of method. For dual media, the fracture permeability obtained by the third type of method using the conventional analysis method may differ from the actual value by tens of times. No method can significantly eliminate the sorption effect. When the core is a dual-medium, only the pressure curves of the upstream positive-pulse method, downstream negative-pulse method and one-chamber method can reflect the characteristics of dual media. The pressure derivative of the one-chamber method cannot reflect the characteristics of dual media at the early time. The pressure derivative of the second type and the upstream positive-pulse downstream negative-pulse method can reflect the complete characteristics of dual media, but their pressure derivative of the constant-slope segment is small, and the interporosity flow parameter may not be identified
Differences in Performance of Models for Heterogeneous Cores during Pulse Decay Tests
No full textFeatured Application
Evaluate the permeability of unconventional reservoir cores.
Abstract Shale and fractured cores often exhibit dual-continuum medium characteristics in pulse decay testing. Dual-continuum medium models can be composed of different flow paths, interporosity flow patterns, and matrix shapes. Various dual-continuum medium models have been used by researchers to analyze the results of pulse decay tests. But the differences in their performance for pulse decay tests have not been comprehensively investigated. The characteristics of the dual-permeability model and the dual-porosity model, the slab matrix, and the spherical matrix in pulse decay testing are compared by numerical modeling in this study. The pressure and pressure derivative curves for different vessel volumes, storativity ratios, interporosity flow coefficients, and matrix-fracture permeability ratios were compared and analyzed. The study found that these models have only a small difference in the interporosity flow stage, and the difference in the matrix shape is not important, and the matrix shape cannot be identified by pulse decay tests. When the permeability of the low permeability medium is less than 1% of the permeability of the high permeability medium, the difference between the dual-permeability model and the dual-porosity model can be ignored. The dual-permeability model approaches the pseudo-steady-state model as the interporosity flow coefficient and vessel volume increase. Compared with the dual-porosity model, the dual-permeability model has a shorter horizontal section of the pressure derivative in the interporosity flow stage. Finally, the conclusions were verified against a case study. This study advances the ability of pulse decay tests to investigate the properties of unconventional reservoir cores
A Vertical Transport Geometry for Electrical Spin Injection and Extraction in Si
No full textSchottky barriers formed between ferromagnetic metal and Semiconductor are of particular interest for spin injection and detection experiments. Here, we investigate electrical spin polarized carrier injection and extraction in Si using a Co/Si/Ni vertical structure built on a 250 nm thick Si membrane. Current-voltage measurements performed on the devices at low temperatures showed evidence of the conduction being dominated by thermionic field emission, which is believed to be the key to spin injection using Schottky junctions. This, however, proved inconclusive as our devices did not show any magnetoresistance signal even at low temperatures. We attribute this partially to the high resistance-area product in our Schottky contacts at spin injection biases. We show the potential of this vertical Spin-device for future experiments by numerical simulation. The results reveal that by growing a thin highly doped Ge layer at the Schottky junctions the resistancearea products could be tuned to obtain high magnetoresistance
FIGURE 1 in Molecular phylogenetics of Pterocyclus (Apiaceae) based on nrDNA ITS sequences: revised circumscription with a restored species
No full textFIGURE 1. Consensus tree obtained from maximum likelihood analysis of sixty-three nrDNA ITS sequences. Numbers above and below nodes are bootstrap support and posterior probability presented as percentages, respectively. The newly sampled accessions are shown in bold.Published as part of Zhou, Jing, Wei, Jin, Niu, Junmei, Liu, Xiaoli & Liu, Zhenwen, 2021, Molecular phylogenetics of Pterocyclus (Apiaceae) based on nrDNA ITS sequences: revised circumscription with a restored species, pp. 131-138 in Phytotaxa 498 (2) on page 133, DOI: 10.11646/phytotaxa.498.2.6, http://zenodo.org/record/542418
FIGURE 2. A in Molecular phylogenetics of Pterocyclus (Apiaceae) based on nrDNA ITS sequences: revised circumscription with a restored species
No full textFIGURE 2. A) Lectotype of Pterocyclus wolffianus Fedde ex H. Wolff from E (E00000149); B) Lectotype of Pterocyclus forrestii (Diels) Pimenov & Kljuykov from E (E00000166); C) Isolectotype of Pterocyclus angelicoides (DC.) Klotzsch from K (K000685357); D) Isotype of Pterocyclus rotundatus (DC.) Pimenov & Kljuykov from K (K000685356).Published as part of Zhou, Jing, Wei, Jin, Niu, Junmei, Liu, Xiaoli & Liu, Zhenwen, 2021, Molecular phylogenetics of Pterocyclus (Apiaceae) based on nrDNA ITS sequences: revised circumscription with a restored species, pp. 131-138 in Phytotaxa 498 (2) on page 134, DOI: 10.11646/phytotaxa.498.2.6, http://zenodo.org/record/542418
Liu Kang
No full textLiu Kang: Essays on Art and Culture is a testament to the inexorable passion of an artist who knew no boundaries. This collection of essays, which Liu Kang wrote over 44 years, offers an insight into the artist’s myriad interests as well as his contributions as a first generation Nanyang artist and art educator. Translated into English for this volume, Liu Kang’s essays are accompanied by commentaries and photographs of the artist-author and his subjects
FIGURE 4. Synidotea laticauda Benedict, 1897 in A new record and mitochondrial identification of Synidotea laticauda Benedict, 1897 (Crustacea: Isopoda: Valvifera: Idoteidae) from the Yangtze Estuary, China
No full textFIGURE 4. Synidotea laticauda Benedict, 1897. Adult male (total length, 13.4 mm). A–G, pereopods 1–7; H, pleopod 2 and appendix masculina; I, penial plate. Scale = 1mm.Published as part of Liu, Wenliang, Liang, Xiaoli & Zhu, Xiaojing, 2017, A new record and mitochondrial identification of Synidotea laticauda Benedict, 1897 (Crustacea: Isopoda: Valvifera: Idoteidae) from the Yangtze Estuary, China, pp. 371-380 in Zootaxa 4294 (3) on page 376, DOI: 10.11646/zootaxa.4294.3.7, http://zenodo.org/record/83566
Distribution, composition and risk assessment of PAHs and PCBs in cryospheric watersheds of the eastern Tibetan Plateau.
No full textPolycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated Biphenyls (PCBs) are significant components of persistent organic pollutants (POPs) and pose a threat to both ecosystems and human health. To explore their spatial distribution, origins, and risk assessment, we collected 25 glacial meltwater and downstream river water samples in the eastern Tibetan Plateau (including the Qilian Mountains in the northeast) during the summer of 2022 (June-July). Our results showed that ∑PAHs and ∑PCBs were present in a wide range from ND-1380 ng/L and ND-1421 ng/L, respectively. Compared to other studies worldwide, the ∑PAHs and ∑PCBs in the Hengduan Mountains were at high levels. The PAHs and PCBs mainly consisted of low-molecular-weight homologs, including Ace, Flu, Phe, and PCB52. Phe was the primary component of PAHs. Glacial meltwater samples generally exhibited low concentration of PAHs and PCB52, whereas downstream river water samples typically showed high concentration of PAHs and PCB52. We attributed this characteristic to the influence of pollutants physicochemical properties, altitude effect, long-range transport (LRT), and local environmental conditions. In the eastern Tibetan Plateau glacier basin (especially in the Hailuogou watersheds), the concentration of PAHs and PCB52 in runoff generally increased with decreasing elevation. We believe that the primary factor affecting the concentration of PAHs and PCB52 in the region is the difference in local human activity inputs from various altitudes. The composition characteristics of PAHs and PCBs suggested that incomplete coal combustion and coking discharge mainly caused PAHs, while the combustion of coal and charcoal and the release of capacitors primarily caused PCBs. We assessed the carcinogenic risk of PAHs and PCBs in the glacier basin of the TP and found that the potential threat of PAHs was stronger than that of PCBs. Overall, this study provides new insights into the ecological security of water resources in eastern Tibetan Plateau. It is significant for controlling PAHs and PCBs emissions, assessing the ecological environment of the glacier watershed, and regional human health
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