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1.
Esophagus ; 2022 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-34993672

RESUMO

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) has a poor prognosis and occurs with high frequency in China. In particular, Fujian is one of the high-incidence areas of ESCC in China and the somatic mutation profile of ESCC there remains unclear. PATIENTS AND METHODS: Whole-exome sequencing (WES) was performed in 49 matched ESCC tumor-normal specimens to examine the somatic mutation profiles. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between mutational profile and survival were derived from Cox regression model. RESULTS: We constructed a preliminary somatic mutation profiling of ESCC in Fujian. Exome sequencing data showed that the main base substitutions in ESCC were C > T transformation (close to 50%), C > A and T > C transversion. The study identified 21 significantly mutated genes, including 8 driver genes and 11 predicted driver genes. Among the 19 driver or predicted driver genes, 9 are novel (OBSCN, PKHD1L1, FSIP2, HRNR, CUBN, CELSR3, SCN7A, TULP4, SRRM2) and 10 have been previously reported. Three mutational signatures were identified to be prevalent in ESCC including Signature_15, Signature_4 and Signature_6, of which Signature_15 was related to prognosis of ESCC (HR 2.81, 95% CI 1.30-6.05; p = 0.008). Survival analysis showed that SCN7A was correlated to overall survival with an HR of 2.76 (95% CI 0.96-7.90, p = 0.058). After controlling for confounding factors such as age, gender, stage and location, the correlation between SCN7A and survival was statistically significant based on multivariate COX regression analysis (HR 4.76, 95% CI 1.20-18.85; p = 0.026, padjust = 0.053). The tumor vascular invasion was associated with SCN7A of ESCC patients (p = 0.028). CONCLUSION: In summary, this study provided comprehensive analysis of the somatic mutation profiles of ESCC, and identified SCN7A and Signature_15 for the prognosis of ESCC for the first time. The findings might serve as a conceptual basis for molecular diagnosis and prevention of ESCC.

2.
Free Radic Biol Med ; 172: 578-589, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34242792

RESUMO

Acetaminophen (APAP) is the leading cause of acute liver failure (ALF), which is characterized by GSH depletion, oxidative stress and mitochondrial dysfunction. However, the specific mechanism of APAP-induced ALF remains to be clarified. In this study, we demonstrated that indoleamine 2,3-dioxygenase 1 (IDO1) aggravated APAP-induced ALF associated with excess lipid peroxidation, which was reversed by lipid peroxidation inhibitor (ferrostatin-1). Meanwhile, IDO1 deficiency effectively decreased the accumulation of reactive nitrogen species. Additionally, IDO1 deficiency prevented against APAP-induced liver injury through suppressing the activation of macrophages, thereby reduced their iron uptake and export, eventually reduced iron accumulation in hepatocytes through transferrin and transferrin receptor axis. In summary, our study confirmed that APAP-induced IDO1 aggravated ALF by triggering excess oxidative and nitrative stress and iron accumulation in liver. These results offer new insights for the clinical treatment of ALF or iron-dysregulated liver diseases in the future.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Dioxigenases , Falência Hepática Aguda , Acetaminofen/toxicidade , Animais , Doença Hepática Induzida por Substâncias e Drogas/genética , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Dioxigenases/metabolismo , Hepatócitos , Ferro/metabolismo , Fígado/metabolismo , Falência Hepática Aguda/induzido quimicamente , Falência Hepática Aguda/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Estresse Oxidativo
3.
Int J Mol Sci ; 22(9)2021 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-34066899

RESUMO

Plant NAC (NAM, ATAF1/2, and CUC2) family is involved in various development processes including Programmed Cell Death (PCD) associated development. However, the relationship between NAC family and PCD-associated cotton pigment gland development is largely unknown. In this study, we identified 150, 153 and 299 NAC genes in newly updated genome sequences of G. arboreum, G. raimondii and G. hirsutum, respectively. All NAC genes were divided into 8 groups by the phylogenetic analysis and most of them were conserved during cotton evolution. Using the vital regulator of gland formation GhMYC2-like as bait, expression correlation analysis screened out 6 NAC genes which were low-expressed in glandless cotton and high-expressed in glanded cotton. These 6 NAC genes acted downstream of GhMYC2-like and were induced by MeJA. Silencing CGF1(Cotton Gland Formation1), another MYC-coding gene, caused almost glandless phenotype and down-regulated expression of GhMYC2-like and the 6 NAC genes, indicating a MYC-NAC regulatory network in gland development. In addition, predicted regulatory mechanism showed that the 6 NAC genes were possibly regulated by light, various phytohormones and transcription factors as well as miRNAs. The interaction network and DNA binding sites of the 6 NAC transcription factors were also predicted. These results laid the foundation for further study of gland-related genes and gland development regulatory network.


Assuntos
Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Gossypium/anatomia & histologia , Gossypium/genética , Pigmentação/genética , Proteínas de Plantas/genética , Cromossomos de Plantas/genética , Diploide , Duplicação Gênica , Perfilação da Expressão Gênica , Inativação Gênica , Genes de Plantas , Modelos Biológicos , Família Multigênica , Filogenia , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Sintenia/genética
4.
BMC Plant Biol ; 21(1): 102, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33602142

RESUMO

BACKGROUND: Gossypium hirsutum L. (cotton) is one of the most economically important crops in the world due to its significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed was limited due to the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and non-ruminant animals. To date, some progress has been made in the pigment gland formation, but the underlying molecular mechanism of its formation was still unclear. RESULTS: In this study, we identified an AP2/ERF transcription factor named GhERF105 (GH_A12G2166), which was involved in the regulation of gland pigmentation by the comparative transcriptome analysis of the leaf of glanded and glandless plants. It encoded an ERF protein containing a converved AP2 domain which was localized in the nucleus with transcriptional activity, and showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing (VIGS) against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants. CONCLUSIONS: These results suggest that GhERF105 contributes to the pigment gland formation and gossypol biosynthesis in partial organs of glanded plant. It also provides a potential molecular basis to generate 'glandless-seed' and 'glanded-plant' cotton cultivar.


Assuntos
Gossypium/crescimento & desenvolvimento , Gossypium/genética , Proteínas de Plantas/genética , Fatores de Transcrição/metabolismo , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Gossypium/química , Gossypium/metabolismo , Gossipol/análise , Gossipol/metabolismo , Folhas de Planta/química , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Domínios Proteicos , Fatores de Transcrição/química , Fatores de Transcrição/genética
5.
Front Pharmacol ; 12: 801730, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35046824

RESUMO

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and continues to rise in the worldwide. Limonin is a triterpenoid compound widely found in the fruits of citrus plants with a wide range of pharmacological effects, including anti-cancer, anti-inflammation, anti-viral, anti-oxidation and liver protection properties. However, the potential molecular mechanism of limonin on NAFLD in zebrafish remains unknown. In this study, zebrafish larvae were exposed to thioacetamide to establish an NAFLD model and the larvae were treated with limonin for 72 h simultaneously. The human liver cell line was stimulated with lipid mixture and meanwhile incubated with limonin for 24 h. The results showed that Limonin significantly reduced the accumulation of lipid droplets in the liver and down-regulated the levels of lipogenic transcription factors FASN and SREBP1 in NAFLD. Limonin suppressed macrophages infiltration and the down-regulated the relative expression levels of the pro-inflammatory factors IL-6, IL-1ß and TNF-α secreted by macrophages. Besides, limonin could reversed the reduction of glutathione and the accumulation of reactive oxygen species through up-regulating NRF2/HO-1 signaling pathway in the liver. In conclusion, this study revealed that limonin has a protective effect on NAFLD due to its resistance to lipid deposition as well as antioxidant and anti-inflammatory actions.

6.
Int J Biol Macromol ; 165(Pt B): 2565-2575, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33736275

RESUMO

The glutathione S-transferases (GSTs) are important enzymes of secondary metabolism in plants. In this study, two putative GSTs, GhGSTF1 and GhGSTF2, were identified as anthocyanin-related GSTs by the transcriptome data of the leaves of Gossypium hirsutum L. TM-1 and T586. The quantitative real-time PCR showed that GhGSTF1 and GhGSTF2 were highly expressed in red leaves and stems of Gossypium hirsutum L. T586. Orthologous genes of GhGSTF2 in two Gossypium barbadense L. 3-79 and Xinhai21 contain bases deletion in N-terminal (GbGSTF2a) and C-terminal (GbGSTF2b) respectively. Among which, GhGSTF1 and GhGSTF2 can restore pigmentation in hypocotyls of Arabidopsis thaliana mutant tt19-7 while GbGSTF2a and GbGSTF2b cannot. Furthermore, in vitro assays showed the recombinant GhGSTF1 and GhGSTF2 had Glutathione S-transferase activities. Fluorescence quenching assays showed that Cya could obviously quench the fluorescence of GhGSTF1, GhGSTF2, GbGSTF2a and GbGSTF2b to lower levels as compared to C3G. Moreover, the transient dual-luciferase assays showed that the promoters of GhGSTF1 and GhGSTF2 could be activated by GhPAP1D at different levels. GUS staining assays showed that their promoters have different activities to light. This study indicated that GhGSTF1 and GhGSTF2 play important roles in anthocyanin accumulation and the regulatory mechanism of anthocyanin accumulation in allotetraploid Gossypium are complicated.


Assuntos
Antocianinas/biossíntese , Perfilação da Expressão Gênica/métodos , Glutationa Transferase/genética , Gossypium/enzimologia , Arabidopsis , Clonagem Molecular , Evolução Molecular , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Glutationa Transferase/metabolismo , Gossypium/genética , Folhas de Planta/enzimologia , Folhas de Planta/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Caules de Planta/enzimologia , Caules de Planta/genética , Distribuição Tecidual , Regulação para Cima
7.
Materials (Basel) ; 12(1)2018 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-30587827

RESUMO

In this study, 2198 Al-Li alloy, a low density and high-performance material for aerospace equipment, was welded using ultrahigh-frequency pulse alternating current with cold metal transfer (UHF-ACCMT). Influence of different ultrahigh-frequency on the formation, porosity, microstructure, microhardness and tensile strength of the welded joints were investigated. The results showed that the coupled ultrahigh-frequency current generated electromagnetic force to stir the liquid metal of molten pool. The weld formation became much better with metallic luster and uniform ripples at frequency of 60 kHz and 70 kHz. The porosity was the minimum at frequency of 60 kHz. Furthermore, the molten pool was scoured and stirred by the electromagnetic force which provided the thermal and dynamic conditions for nucleation and grain refinement, the width of fine equiaxed grain zone became larger, and the number of equiaxed non-dendrite grains increased. With the grain refining and crystallize transition, the average microhardness and tensile strength of the joints at frequency of 60 kHz reached up the highest value, 116 HV0.1 and 338 MPa, respectively. The fracture of the welded joints presented the characteristics of quasi-cleavage fracture.

8.
PeerJ ; 6: e6071, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30581669

RESUMO

The AP2/ERF superfamily of transcription factors is one of the largest transcription factor families in plants and plays an important role in plant development processes and stress responses. In this study, BjABR1, an AP2/ERF superfamily gene, from tuber mustard (Brassica juncea var. tumida Tsen et Lee), sharing high amino acid sequence similarity with the AtABR1 (Arabidopsis thaliana AP2-like abscisic acid repressor 1) gene, were performed functional research, and the ABR1 homologous genes in Brassica species were identified and performed phylogenetic analysis. The promoter sequence of BjABR1 contained many phytohormone- and stress-related cis-elements; ABA (abscisic acid) and abiotic stresses can induce BjABR1 expression in tuber mustard; overexpression of BjABR1 in Arabidopsis can alleviate plant sensitivity to ABA and salt and osmotic stresses, and the alleviation may be due to changes in stress/ABA-induced gene expression. These results indicated that BjABR1 functions in ABA and abiotic stress responses. By BLAST searches against the genome database of five Brassica species (three diploids, B. rapa, B. nigra, and B. oleracea, and two allotetraploid, B. juncea and B. napus) using the protein sequence of AtABR1, 3, 3, 3, 6, and 5 ABR1 homologous genes in B. nigra, B. rapa, B. oleracea, B. juncea, and B. napus were identified, respectively, and they shared high sequence similarity. By sequence analysis, annotation mistakes of the protein-coding regions of two ABR1 homologous genes, GSBRNA2T00134741001 and BjuB007684, were found and corrected. Then, the evolution analysis of these ABR1 homologous genes showed that the ancestor of the three diploid species had three ABR1 homologous genes and each diploid inherited all the three genes from their ancestor; then, allotetraploid B. juncea inherited all the six genes from B. rapa and B. nigra with no gene lost, while allotetraploid B. napus inherited all the three genes from B. oleracea and two genes from B. rapa with one gene lost, indicating that ABR1 homologous genes possessed greater hereditary conservation in Brassica species. The ABR1 homologous genes between B. rapa and B. oleracea shared much higher sequence similarity compared to that of B. nigra in diploid species, indicating that ABR1 homologous genes in B. nigra had experienced more rapid evolution, and B. rapa and B. oleracea may share closer relationship compared to B. nigra. Moreover, the spatial and temporal expression analysis of six ABR1 homologous genes of tuber mustard showed that they possessed different expression models. These results imply that ABR1 homologous genes are important to Brassica plants, and they may possess similar function in ABA and abiotic stress responses but play a role in different tissues and growing stages of plant. This study will provide the foundation to the functional research of ABR1 homologous genes in the Brassica species and help to reveal and understand the evolution mechanisms of Brassica species.

9.
Adv Mater ; : e1802016, 2018 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-29984538

RESUMO

Microstructure engineering is an effective strategy to reduce lattice thermal conductivity (κl ) and enhance the thermoelectric figure of merit (zT). Through a new process based on melt-centrifugation to squeeze out excess eutectic liquid, microstructure modulation is realized to manipulate the formation of dislocations and clean grain boundaries, resulting in a porous network with a platelet structure. In this way, phonon transport is strongly disrupted by a combination of porosity, pore surfaces/junctions, grain boundaries, and lattice dislocations. These collectively result in a ≈60% reduction of κl compared to zone melted ingot, while the charge carriers remain relatively mobile across the liquid-fused grains. This porous material displays a zT value of 1.2, which is higher than fully dense conventional zone melted ingots and hot pressed (Bi,Sb)2 Te3 alloys. A segmented leg of melt-centrifuged Bi0.5 Sb1.5 Te3 and Bi0.3 Sb1.7 Te3 could produce a high device ZT exceeding 1.0 over the whole temperature range of 323-523 K and an efficiency up to 9%. The present work demonstrates a method for synthesizing high-efficiency porous thermoelectric materials through an unconventional melt-centrifugation technique.

10.
Science ; 360(6390): 778-783, 2018 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-29773748

RESUMO

Thermoelectric technology enables the harvest of waste heat and its direct conversion into electricity. The conversion efficiency is determined by the materials figure of merit ZT Here we show a maximum ZT of ~2.8 ± 0.5 at 773 kelvin in n-type tin selenide (SnSe) crystals out of plane. The thermal conductivity in layered SnSe crystals is the lowest in the out-of-plane direction [two-dimensional (2D) phonon transport]. We doped SnSe with bromine to make n-type SnSe crystals with the overlapping interlayer charge density (3D charge transport). A continuous phase transition increases the symmetry and diverges two converged conduction bands. These two factors improve carrier mobility, while preserving a large Seebeck coefficient. Our findings can be applied in 2D layered materials and provide a new strategy to enhance out-of-plane electrical transport properties without degrading thermal properties.

11.
PeerJ ; 6: e4500, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29576969

RESUMO

Circular RNAs (circRNAs), a class of recently discovered non-coding RNAs, play a role in biological and developmental processes. A recent study showed that circRNAs exist in plants and play a role in their environmental stress responses. However, cotton circRNAs and their role in Verticillium wilt response have not been identified up to now. In this study, two CSSLs (chromosome segment substitution lines) of G.barbadense introgressed into G. hirsutum, CSSL-1 and CSSL-4 (a resistant line and a susceptible line to Verticillium wilt, respectively), were inoculated with V. dahliae for RNA-seq library construction and circRNA analysis. A total of 686 novel circRNAs were identified. CSSL-1 and CSSL-4 had similar numbers of circRNAs and shared many circRNAs in common. However, CSSL-4 differentially expressed approximately twice as many circRNAs as CSSL-1, and the differential expression levels of the common circRNAs were generally higher in CSSL-1 than in CSSL-4. Moreover, two C-RRI comparisons, C-RRI-vs-C-RRM and C-RRI-vs-C-RSI, possessed a large proportion (approximately 50%) of the commonly and differentially expressed circRNAs. These results indicate that the differentially expressed circRNAs may play roles in the Verticillium wilt response in cotton. A total of 280 differentially expressed circRNAs were identified. A Gene Ontology analysis showed that most of the 'stimulus response' term source genes were NBS family genes, of which most were the source genes from the differentially expressed circRNAs, indicating that NBS genes may play a role in Verticillium wilt resistance and might be regulated by circRNAs in the disease-resistance process in cotton.

12.
Adv Sci (Weinh) ; 4(11): 1700199, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-29201615

RESUMO

Nanoporous architecture has long been predicted theoretically for its proficiency in suppressing thermal conduction, but less concerned as a practical approach for better thermoelectric materials hitherto probably due to its technical challenges. This article demonstrates a study on nanoporous PbSe-SiO2 composites fabricated by a facile method of mechanical alloying assisted by subsequent wet-milling and then spark plasma sintering. Owing to the formation of random nanopores and additional interface scattering, the lattice thermal conductivity is limited to a value as low as 0.56 W m-1 K-1 at above 600 K, almost the same low level achieved by introducing nanoscale precipitates. Besides, the room-temperature electrical transport is found to be dominated by the grain-boundary potential barrier scattering, whose effect fades away with increasing temperatures. Consequently, a maximum ZT of 1.15 at 823 K is achieved in the PbSe + 0.7 vol% SiO2 composition with >20% increase in average ZT, indicating the great potential of nanoporous structuring toward high thermoelectric conversion efficiency.

13.
Adv Sci (Weinh) ; 4(11): 1700259, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-29201622

RESUMO

Bi2Te3 thermoelectric materials are utilized for refrigeration for decades, while their application of energy harvesting requires stable thermoelectric and mechanical performances at elevated temperatures. This work reveals that a steady zT of ≈0.85 at 200 to 300 °C can be achieved by doping small amounts of copper iodide (CuI) in Bi2Te2.2Se0.8-silicon carbide (SiC) composites, where SiC nanodispersion enhances the flexural strength. It is found that CuI plays two important roles with atomic Cu/I dopants and CuI precipitates. The Cu/I dopants show a self-tuning behavior due to increasing solubility with increasing temperatures. The increased doping concentration increases electrical conductivity at high temperatures and effectively suppresses the intrinsic excitation. In addition, a large reduction of lattice thermal conductivity is achieved due to the "in situ" CuI nanoprecipitates acting as phonon-scattering centers. Over 60% reduction of bipolar thermal conductivity is achieved, raising the maximum useful temperature of Bi2Te3 for substantially higher efficiency. For module applications, the reported materials are suitable for segmentation with a conventional ingot. This leads to high device ZT values of ≈0.9-1.0 and high efficiency up to 9.2% from 300 to 573 K, which can be of great significance for power generation from waste heat.

14.
BMC Genomics ; 18(1): 292, 2017 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-28403834

RESUMO

BACKGROUND: Nucleotide binding site (NBS) genes encode a large family of disease resistance (R) proteins in plants. The availability of genomic data of the two diploid cotton species, Gossypium arboreum and Gossypium raimondii, and the two allotetraploid cotton species, Gossypium hirsutum (TM-1) and Gossypium barbadense allow for a more comprehensive and systematic comparative study of NBS-encoding genes to elucidate the mechanisms of cotton disease resistance. RESULTS: Based on the genome assembly data, 246, 365, 588 and 682 NBS-encoding genes were identified in G. arboreum, G. raimondii, G. hirsutum and G. barbadense, respectively. The distribution of NBS-encoding genes among the chromosomes was nonrandom and uneven, and was tended to form clusters. Gene structure analysis showed that G. arboreum and G. hirsutum possessed a greater proportion of CN, CNL, and N genes and a lower proportion of NL, TN and TNL genes compared to that of G. raimondii and G. barbadense, while the percentages of RN and RNL genes remained relatively unchanged. The percentage changes among them were largest for TNL genes, about 7 times. Exon statistics showed that the average exon numbers per NBS gene in G. raimondii and G. barbadense were all greater than that in G. arboretum and G. hirsutum. Phylogenetic analysis revealed that the TIR-NBS genes of G. barbadense were closely related with that of G. raimondii. Sequence similarity analysis showed that diploid cotton G. arboreum possessed a larger proportion of NBS-encoding genes similar to that of allotetraploid cotton G. hirsutum, while diploid G. raimondii possessed a larger proportion of NBS-encoding genes similar to that of allotetraploid cotton G. barbadense. The synteny analysis showed that more NBS genes in G. raimondii and G. arboreum were syntenic with that in G. barbadense and G. hirsutum, respectively. CONCLUSIONS: The structural architectures, amino acid sequence similarities and synteny of NBS-encoding genes between G. arboreum and G. hirsutum, and between G. raimondii and G. barbadense were the highest among comparisons between the diploid and allotetraploid genomes, indicating that G. hirsutum inherited more NBS-encoding genes from G. arboreum, while G. barbadense inherited more NBS-encoding genes from G. raimondii. This asymmetric evolution of NBS-encoding genes may help to explain why G. raimondii and G. barbadense are more resistant to Verticillium wilt, whereas G. arboreum and G. hirsutum are more susceptible to Verticillium wilt. The disease resistances of the allotetraploid cotton were related to their NBS-encoding genes especially in regard from which diploid progenitor they were derived, and the TNL genes may have a significant role in disease resistance to Verticillium wilt in G. raimondii and G. barbadense.


Assuntos
Resistência à Doença , Gossypium/classificação , Gossypium/genética , Proteínas de Plantas/genética , Sítios de Ligação , Mapeamento Cromossômico/métodos , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Família Multigênica , Filogenia , Análise de Sequência de DNA , Sintenia
15.
Sci Rep ; 7: 43262, 2017 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-28240324

RESUMO

P-type SnS compound and SnS1-xSex solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS-pressurizing direction in the temperature range 323-823 Κ. SnS compound and SnS1-xSex solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m-1 K-1 at 823 K for the composition SnS0.5Se0.5. With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS0.2Se0.8 along the parallel direction.

16.
J Am Chem Soc ; 138(28): 8875-82, 2016 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-27348333

RESUMO

Recent findings about ultrahigh thermoelectric performance in SnSe single crystals have stimulated related research on this simple binary compound, which is focused mostly on its polycrystalline counterparts, and particularly on electrical property enhancement by effective doping. This work systematically investigated the thermoelectric properties of polycrystalline SnSe doped with three alkali metals (Li, Na, and K). It is found that Na has the best doping efficiency, leading to an increase in hole concentration from 3.2 × 10(17) to 4.4 × 10(19) cm(-3) at room temperature, accompanied by a drop in Seebeck coefficient from 480 to 142 µV/K. An equivalent single parabolic band model was found adequate to capture the variation tendency of Seebeck coefficient with doping levels within a wide range. A mixed scattering of carriers by acoustic phonons and grain boundaries is suitable for numerically understanding the temperature-dependence of carrier mobility. A maximum ZT of ∼0.8 was achieved in 1% Na- or K-doped SnSe at 800 K. Possible strategies to improve the mobility and ZT of polycrystals were also proposed.

17.
Phys Chem Chem Phys ; 17(44): 30102-9, 2015 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-26496971

RESUMO

SnSe, a "simple" and "old" binary compound composed of earth-abundant elements, has been reported to exhibit a high thermoelectric performance in single crystals, which stimulated recent interest in its polycrystalline counterparts. This work investigated the electrical and thermal transport properties of pristine and Na-doped SnSe1-xTex polycrystals prepared by mechanical alloying and spark plasma sintering. It is revealed that SnSe1-xTex solid solutions are formed when x ranges from 0 to 0.2. An energy barrier scattering mechanism is suitable for understanding the electrical conducting behaviour observed in the present SnSe polycrystalline materials, which may be associated with abundant defects at grain boundaries. The thermal conductivity was greatly reduced upon Te substitution due to alloy scattering of phonons as well explained by the Debye model. Due to the increased carrier concentration by Na-doping, thermoelectric figure of merit (ZT) was enhanced in the whole temperature range with a maximum value of 0.72 obtained at a relatively low temperature (773 K) for Sn0.99Na0.01Se0.84Te0.16.

18.
Phys Chem Chem Phys ; 17(19): 13006-12, 2015 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-25912375

RESUMO

Both lead selenide (PbSe) and tin selenide (SnSe) are promising thermoelectric compounds consisting of earth-abundant elements, between which solid solutions can be formed over a wide composition range. This study investigated the electrical and thermal transport properties of n-type Pb1-xSnxSe (x = 0, 0.01, 0.05, 0.1 and 0.15) solid solutions with emphasis on the effect of Sn substitution. Small amounts of Sn substitution (x ≤ 0.1) increased electrical conductivity but showed less influence on the Seebeck coefficient, leading to improved power factors, which were revealed to be associated with the generation of native Se vacancies. The electrical conductivity tended to decrease when x > 0.1 due to the alloying effect, consequently the thermoelectric figure of merit was not further increased, even though the thermal conductivity can be reduced by increasing Sn content. A maximum dimensionless figure of merit ZT of up to 1.0 was obtained at moderate temperature (773 K) for the composition of Pb0.9Sn0.1Se.

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