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Jiao WY, Hu R, Han SH, Luo YF, Yuan HM, Li MK, Liu HJ. Surprisingly good thermoelectric performance of monolayer C 3N. Nanotechnology 2021; 33:045401. [PMID: 34653997 DOI: 10.1088/1361-6528/ac302c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
The rapid emergence of graphene has attracted numerous efforts to explore other two-dimensional materials. Here, we combine first-principles calculations and Boltzmann theory to investigate the structural, electronic, and thermoelectric transport properties of monolayer C3N, which exhibits a honeycomb structure very similar to graphene. It is found that the system is both dynamically and thermally stable even at high temperature. Unlike graphene, the monolayer has an indirect band gap of 0.38 eV and much lower lattice thermal conductivity. Moreover, the system exhibits obviously larger electrical conductivity and Seebeck coefficients for the hole carriers. Consequently, theZTvalue ofp-type C3N can reach 1.4 at 1200 K when a constant relaxation time is predicted by the simple deformation potential theory. However, such a largerZTis reduced to 0.6 if we fully consider the electron-phonon coupling. Even so, the thermoelectric performance of monolayer C3N is still significantly enhanced compared with that of graphene, and is surprisingly good for low-dimensional thermoelectric materials consisting of very light elements.
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Affiliation(s)
- W Y Jiao
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - R Hu
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - S H Han
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Y F Luo
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - H M Yuan
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - M K Li
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - H J Liu
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
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Han SH, Zhou ZZ, Sheng CY, Liu JH, Wang L, Yuan HM, Liu HJ. High thermoelectric performance of half-Heusler compound BiBaK with intrinsically low lattice thermal conductivity. J Phys Condens Matter 2020; 32:425704. [PMID: 32624508 DOI: 10.1088/1361-648x/aba2e7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Half-Heusler compounds usually exhibit relatively higher lattice thermal conductivity that is undesirable for thermoelectric applications. Here we demonstrate by first-principles calculations and Boltzmann transport theory that the BiBaK system is an exception, which has rather low thermal conductivity as evidenced by very small phonon group velocity and relaxation time. Detailed analysis indicates that the heavy Bi and Ba atoms form a cage-like structure, inside which the light K atom rattles with larger atomic displacement parameters. In combination with its good electronic transport properties, the BiBaK shows a maximum n-type ZT value of 1.9 at 900 K, which outperforms most half-Heusler thermoelectric materials.
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Affiliation(s)
- S H Han
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
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Huyan S, Deng LZ, Wu Z, Zhao K, Sun JY, Wu LJ, Zhao YY, Yuan HM, Gooch M, Lv B, Zhu Y, Chen S, Chu CW. Low-temperature microstructural studies on superconducting CaFe 2As 2. Sci Rep 2019; 9:6393. [PMID: 31015499 PMCID: PMC6478709 DOI: 10.1038/s41598-019-42660-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/28/2019] [Indexed: 11/09/2022] Open
Abstract
Undoped CaFe2As2 (Ca122) can be stabilized in two slightly different non-superconducting tetragonal phases, PI and PII, through thermal treatments. Upon proper annealing, superconductivity with a Tc up to 25 K emerges in the samples with an admixture of PI and PII phases. Systematic low-temperature X-ray diffraction studies were conducted on undoped Ca122 samples annealed at 350 °C over different time periods. In addition to the diffraction peaks associated with the single-phase aggregation of PI and PII, a broad intermediate peak that shifts with annealing time was observed in the superconducting samples only. Our simulation of phase distribution suggests that the extra peak is associated with the admixture of PI and PII on the nanometer scale. High-resolution transmission electron microscopy confirms the existence of these nano-scale phase admixtures in the superconducting samples. These experimental results and simulation analyses lend further support for our conclusion that interfacial inducement is the most reasonable explanation for the emergence of superconductivity in undoped Ca122 single crystals.
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Affiliation(s)
- S Huyan
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA.
| | - L Z Deng
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - Z Wu
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - K Zhao
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - J Y Sun
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - L J Wu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Y Y Zhao
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing, China
| | - H M Yuan
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - M Gooch
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - B Lv
- Department of Physics, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Y Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - S Chen
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA
| | - C W Chu
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX, 77204-5005, USA. .,Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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Yang H, Liu L, Liang BS, Yuan HM, Tian MJ, Yang YX, Huang Y. Vesicle-Like and 3D-Hexagonal Mesoporous SiO 2: Preparation and Laccase Adsorption Properties. ADSORPT SCI TECHNOL 2015. [DOI: 10.1260/0263-6174.33.10.831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- H. Yang
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - L. Liu
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - B. S. Liang
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - H. M. Yuan
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130012, China
| | - M. J. Tian
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Y. X. Yang
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
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Zhang LG, Chang Y, Zhang XF, Guan FZ, Yuan HM, Yu Y, Zhao LJ. Analysis of the genetic diversity of Chinese native Cannabis sativa cultivars by using ISSR and chromosome markers. Genet Mol Res 2014; 13:10490-500. [PMID: 25511032 DOI: 10.4238/2014.december.12.10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hemp (Cannabis sativa) is an important fiber crop, and native cultivars exist widely throughout China. In the present study, we analyzed the genetic diversity of 27 important Chinese native hemp cultivars, by using inter-simple sequence repeats (ISSR) and chromosome markers. We determined the following chromosome formulas: 2n = 20 = 14m + 6sm; 2n = 20 = 20m; 2n = 20 = 18m + 2sm; 2n = 20 = 16m + 4sm; and 2n = 20 = 12m + 8sm. The results of our ISSR analysis revealed the genetic relationships among the 27 cultivars; these relationships were analyzed by using the unweighted pair-group method based on DNA polymorphism. Our results revealed that all of the native cultivars showed considerable genetic diversity. At a genetic distance of 0.324, the 27 varieties could be classified into five categories; this grouping corresponded well with the chromosome formulas. All of the investigated hemp cultivars represent relatively primitive types; moreover, the genetic distances show a geographical distribution, with a small amount of regional hybridity.
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Affiliation(s)
- L G Zhang
- College of Life Science, Northeast Agricultural University, Harbin, China
| | - Y Chang
- College of Life Science, Northeast Agricultural University, Harbin, China
| | - X F Zhang
- College of Mathematics and Information Sciences of Guangxi University, Nanning, China
| | - F Z Guan
- Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - H M Yuan
- Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - Y Yu
- Institute of Industrial Crops, Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - L J Zhao
- Institute of Crop Breeding, Heilongjiang Academy of Agricultural Sciences, Harbin, China
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Mittag TW, Danias J, Pohorenec G, Yuan HM, Burakgazi E, Chalmers-Redman R, Podos SM, Tatton WG. Retinal damage after 3 to 4 months of elevated intraocular pressure in a rat glaucoma model. Invest Ophthalmol Vis Sci 2000; 41:3451-9. [PMID: 11006238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
PURPOSE To characterize a long-term elevated intraocular pressure (IOP) glaucoma model in the rat with respect to electroretinographic (ERG) changes and the pattern and mechanism of retinal ganglion cell (RGC) death. METHODS; An approximate doubling of IOP was induced in one eye (G) of female Wistar rats (150-180 g) by cautery of 3 episcleral/limbal veins. At intervals over 3 to 4 months, measurements of IOP and ERG changes (contact-lens electrode) were made in both the G and contralateral normal (N) eyes. At the end of 3 to 4 months of elevated IOP, RGCs were fluorescently labeled with Fluorogold (retrogradely from the superior colliculus), or retinas were labeled by intravitreal injection of a mitochondrial potential indicator dye and stained for apoptotic nuclei with a DNA dye. Flatmounts of fixed, dye-labeled retinas were examined by epifluorescence, confocal, or interference contrast microscopy. RESULTS Elevated IOP was consistently maintained for up to 4 months in G eyes, but ERG a- and b-waves showed a statistically significant decline, of 30% to 40% in amplitude, after 3 months. Loss of RGCs in G retinas was primarily focal with no statistically significant loss demonstrable outside of the focal areas when assessed by an area sampling method for counting RGCs, which totaled 2% to 3% of the entire retinal area. Mitochondrial membrane potential of cells in the RGC layer was reduced by 17.5% (P: < 0.05) in regions surrounding areas of focal loss compared with comparable locations in control N eyes. After 3.5 months' elevated IOP the G retinas showed cell nuclei at various stages of apoptosis, from initial DNA condensation to fragmentation. CONCLUSIONS The three-vein episcleral/limbal vein occlusion model for inducing glaucomatous pathology in the rat eye gives a consistent long-term elevation of IOP. After 3 to 4 months of approximately 100% increased IOP, the ERG responses begin to decline, there is a variable focal loss of RGCs, and some of the remaining RGCs show characteristics of stress and apoptosis. These changes seem consistent with retinal damage in human glaucoma (focal field defects), and this rat model appears to mimic some features of primary open-angle glaucoma.
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Affiliation(s)
- T W Mittag
- Departments of Ophthalmology and. Neurology, Mount Sinai School of Medicine, New York University, New York 10029-6574, USA.
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Abstract
An organic molecule containing cobalt phosphate (denoted CoPO-GIS) which is isostructural with the zeolite gismondine has been synthesized under solvothermal conditions by using [Co(en)3]Cl3 and phosphoric acid as the reactants and ethylene glycol as the solvent. CoPO-GIS ((H3NCH2CH2NH3)0.5.CoPO4) crystallizes in the monoclinic space group C2/c with a = 14.744(3) A, b = 8.850(3) A, c = 10.062(3) A, beta = 131.609(19) degrees, and Z = 8. The structure consists of a 3-D network of strictly alternating CoO4 and PO4 tetrahedra interconnected by oxygen bridges, and the charge-balancing diprotonated ethylenediamine cations are highly ordered in the cages of the CoPO4 framework. CoPO-GIS is the only amine-containing cobalt phosphate with a known zeolite topology.
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Affiliation(s)
- H M Yuan
- Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130023, People's Republic of China
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Figueiredo-Pereira ME, Chen WE, Yuan HM, Wilk S. A novel chymotrypsin-like component of the multicatalytic proteinase complex optimally active at acidic pH. Arch Biochem Biophys 1995; 317:69-78. [PMID: 7872805 DOI: 10.1006/abbi.1995.1137] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The multicatalytic proteinase complex (MPC) or proteasome is a multimeric, high-molecular-weight (700,000), extralysosomal proteolytic enzyme found in eukaryotes and in archaebacteria. Its multiple catalytic sites grant it a broad cleavage specificity toward short peptides and protein substrates. The pH optima of the catalytic activities of MPC are in the neutral or slightly alkaline range. We present here evidence for cryptic catalytic components of MPC optimally active at an acidic pH. Studies with a hydrophobic fluorescent probe provide direct evidence for conformational changes brought about by exposing the complex to an acidic environment. One of the newly described components, designated "acidic chymotrypsin-like activity," cleaves the Leu-2-naphthylamide bond in the substrate Boc-Val-Glu-Ala-Leu-2-naphythylamide. Compared with the classical "neutral" chymotrypsin-like activity defined by cleavage of the Leu-p-nitroanilide bond in Z-Gly-Gly-Leu-p-nitroanilide, the newly described component is not inhibited by monovalent cations and is less sensitive to the peptidyl aldehyde Z-Gly-Gly-leucinal, an inhibitor of the neutral chymotrypsin-like activity. In addition, we describe the properties of a novel potent peptidyl aldehyde, Z-Ile-Glu(OtBu)-Ala-leucinal, which is an inhibitor of both the acidic and neutral chymotrypsin-like activities of MPC, with IC50 values of 0.25 and 6.5 microM, respectively. In the presence of 65 microM of the newly synthesized peptidyl aldehyde, other MPC components such as the trypsin-like and peptidyl-glutamyl peptide hydrolyzing activities were decreased only by 14 and 9%, respectively. The hydrophobicity, potency, and specificity of Z-Ile-Glu(OtBu)-Ala-leucinal toward the chymotrypsin-like activities of the complex make it a valuable pharmacological tool with which to investigate the physiological roles of MPC.
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Affiliation(s)
- M E Figueiredo-Pereira
- Department of Pharmacology, Mount Sinai School of Medicine, City University of New York, New York 10029
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