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1.
Artigo em Inglês | MEDLINE | ID: mdl-38943223

RESUMO

Se-free n-type (Bi,Sb)2Te3 thermoelectric materials, outperforming traditional n-type Bi2(Te,Se)3, emerge as a compelling candidate for practical applications of recovering low-grade waste heat. A 100% improvement in the maximum ZT of n-type Bi1.7Sb0.3Te3 is demonstrated by using melt-spinning and excess Te-assisted transient liquid phase sintering (LPS). Te-rich sintering promotes the formation of intrinsic defects (TeBi), elevating the carrier concentration and enhancing the electrical conductivity. Melt-spinning with excess Te fine-tunes the electronic band, resulting in a high power-factor of 0.35 × 10-3 W·m-1 K-2 at 300 K. Rapid volume change during sintering induces the formation of dislocation networks, significantly suppressing the lattice thermal conductivity (0.4 W·m-1 K-1). The developed n-type legs achieve a high maximum ZT of 1.0 at 450 K resulting in a 70% improvement in the output power of the thermoelectric device (7.7 W at a temperature difference of 250 K). This work highlights the synergy between melt-spinning and transient LPS, advancing the tailored control of both electronic and thermal properties in thermoelectric technology.

2.
Phys Chem Chem Phys ; 26(26): 18041-18047, 2024 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-38895773

RESUMO

Nanostructured thermoelectric materials ideally reduce lattice thermal conductivity without harming the electrical properties. Thus, to truly improve the thermoelectric performance, the quality factor, which is proportional to the weighted mobility divided by the lattice thermal conductivity of the material, must be improved. Precipitates of In2Te3 form in the state-of-the-art Bi2Te3 with crystallographic alignment to the Bi2Te3 structure. Like epitaxy in films, this can be called endotaxy in solids. This natural epitaxy in a 3-dimensional solid is ideally situated to scatter phonons but produces minimal electronic scattering and, therefore, maintains high mobility. Here, we study the effects of In-alloying in Bi2Te3 at high In concentrations (about 4 at%), enough to produce the endotaxial microstructure. It is found that such concentrations of indium in Bi2Te3 significantly alter the electronic structure, reducing the effective mass and weighted mobility so significantly as to effectively destroy the thermoelectric properties even though the lattice thermal conductivity is successfully reduced.

3.
Materials (Basel) ; 17(5)2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38473477

RESUMO

The discoloration switching appearing in the initial and final growth stages of 4H-silicon carbide (4H-SiC) single crystals grown using the physical vapor transport (PVT) technique was investigated. This phenomenon was studied, investigating the correlation with linear-type micro-pipe defects on the surface of 4H-SiC single crystals. Based on the experimental results obtained using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and micro-Raman analysis, it was deduced that the orientation of the 4H-SiC c-axis causes an axial change that correlates with low levels of carbon. In addition, it was confirmed that the incorporation of additional elements and the concentrations of these doped impurity elements were the main causes of discoloration and changes in growth orientation. Overall, this work provides guidelines for evaluating the discoloration switching in 4H-SiC single crystals and contributes to a greater understanding of this phenomenon.

4.
Materials (Basel) ; 17(4)2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38399165

RESUMO

In this study, Al2O3-siloxane composite thermal pads were fabricated using a tape-casting technique, and the thermal conductivity effect of the Al2O3 nanoparticle powder synthesized using a flame fusion process on siloxane composite thermal pads was investigated. Furthermore, various case studies were implemented, wherein the synthesized Al2O3 nanoparticle powder was subjected to different surface treatments, including dehydration, decarbonization, and silylation, to obtain Al2O3-siloxane composite thermal pads with high thermal conductivity. The experimental results confirmed that the thermal conductivity of the Al2O3-siloxane composite pads improved when fabricated using surface-treated Al2O3 nanoparticle powder synthesized with an optimally spheroidized crystal structure compared to that produced using non-treated Al2O3 nanoparticle powder. Therefore, this study provides guidelines for fabricating Al2O3-siloxane composite thermal pads with high thermal conductivity in the field of thermal interface materials.

5.
RSC Adv ; 14(10): 7081-7087, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38414988

RESUMO

SnSe2 with its layered structure is a promising thermoelectric material with intrinsically low lattice thermal conductivity. However, its poor electronic transport properties have motivated extensive doping studies. Br doping effectively improves the power factor and converts the dimorphic SnSe2 to a fully hexagonal structure. To understand the mechanisms underlying the power factor improvement of Br-doped SnSe2, the electronic band parameters of Br-doped dimorphic and hexagonal SnSe2 should be evaluated separately. Using the single parabolic band model, we estimate the intrinsic mobility and effective mass of the Br-doped dimorphic and hexagonal SnSe2. While Br doping significantly improves the mobility of dimorphic SnSe2 (with the dominant hexagonal phase), it results in a combination of band convergence and band flattening in fully hexagonal SnSe2. Br-doped dimorphic SnSe2 is predicted to exhibit higher thermoelectric performance (zT ∼0.23 at 300 K) than Br-doped fully hexagonal SnSe2 (zT ∼0.19 at 300 K). Characterisation of the other, currently unidentified, structural phases of dimorphic SnSe2 will enable us to tailor the thermoelectric properties of Br-doped SnSe2.

6.
Metabolites ; 13(7)2023 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-37512544

RESUMO

Breath volatile organic compound (VOC) analysis is a non-invasive tool for assessing health status; the compositional profile of these compounds in the breath of patients with chronic kidney disease is believed to change with decreasing renal function. We aimed to identify breath VOCs for recognizing patients with chronic kidney disease. Using thermal desorption-gas chromatography/mass spectrometry, untargeted analysis of breath markers was performed using breath samples of healthy controls (n = 18) versus non-dialysis (n = 21) and hemodialysis (n = 12) patients with chronic kidney disease in this cross-sectional study. A total of 303 VOCs alongside 12 clinical variables were used to determine the breath VOC profile. Metabolomic analysis revealed that age, systolic blood pressure, and fifty-eight breath VOCs differed significantly between the chronic kidney disease group (non-dialysis + hemodialysis) and healthy controls. Thirty-six VOCs and two clinical variables that showed significant associations with chronic kidney disease in the univariate analysis were further analyzed. Different spectra of breath volatile organic compounds between the control and chronic kidney disease groups were obtained. A multivariate model incorporating age, 2-methyl-pentane, and cyclohexanone showed high performance (accuracy, 86%) in identifying patients with chronic kidney disease with odds ratios of 0.18 (95% CI, 0.07-2.49, p = 0.013); 2.10 (0.94-2.24, p = 0.025); and 2.31 (0.88-2.64, p = 0.008), respectively. Hence, this study showed that renal dysfunction induces a characteristic profile of breath VOCs that can be used as non-invasive potential biomarkers in screening tests for CKD.

7.
Discov Nano ; 18(1): 47, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-37382702

RESUMO

A high-performance gas sensor operating at room temperature is always favourable since it simplifies the device fabrication and lowers the operating power by eliminating a heater. Herein, we fabricated the ammonia (NH3) gas sensor by using Au nanoparticle-decorated TiO2 nanosheets, which were synthesized via two distinct processes: (1) preparation of monolayer TiO2 nanosheets through flux growth and a subsequent chemical exfoliation and (2) decoration of Au nanoparticles on the TiO2 nanosheets via hydrothermal method. Based on the morphological, compositional, crystallographic, and surface characteristics of this low-dimensional nano-heterostructured material, its temperature- and concentration-dependent NH3 gas-sensing properties were investigated. A high response of ~ 2.8 was obtained at room temperature under 20 ppm NH3 gas concentration by decorating Au nanoparticles onto the surface of TiO2 nanosheets, which generated oxygen defects and induced spillover effect as well.

8.
ChemistryOpen ; 12(3): e202200263, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36855332

RESUMO

Zintl compounds are promising thermoelectric materials for power generation as their electronic and thermal transport properties can be simultaneously engineered with anion/cation alloying. Recently, a peak thermoelectric figure-of-merit, zT, of 1.4 was achieved in a (Yb0.9 Mg0.1 )Cd1.2 Mg0.4 Zn0.4 Sb2 Zintl phase at 700 K. Although the effects of alloying Zn in lattice thermal conductivity had been studied thoroughly, how the Zn alloying affects its electronic transport properties has not yet been fully investigated. This study evaluates how the Zn alloying at Cd sites alters the band parameters of (Yb0.9 Mg0.1 )Cd1.6-x Mg0.4 Znx Sb2 (x=0-0.6) using the Single Parabolic Band model at 700 K. The Zn alloying increased the density-of-states effective mass (md * ) from 0.87 to 0.97 m0 . Among Zn-alloyed samples, the md * of the x=0.4 sample was the lowest (0.93 m0 ). The Zn alloying decreased the non-degenerate mobility (µ0 ) from 71 to 57 cm2 s-1 V-1 . Regardless of Zn alloying content, the µ0 of the Zn-alloyed samples were similar (∼57 cm2 s-1 V-1 ). Consequently, the x=0.4 with the highest zT exhibited the lowest weighted mobility (µW ). The lowest µW represents the lowest theoretical electronic transport properties among other x. The highest zT at x=0.4 despite the lowest µW was explained with a significant lattice thermal conductivity reduction achieved with Zn alloying with x=0.4, which outweighed the deteriorated electronic transport properties also due to the alloying.

9.
Yonsei Med J ; 64(2): 104-110, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36719017

RESUMO

PURPOSE: Pulmonary thromboembolism is a potentially life-threatening condition in patients with heart disease; however, limited studies discussing long-term outcomes exist. This study aimed to investigate the long-term outcomes of pulmonary endarterectomy (PEA) in patients with chronic thromboembolic pulmonary hypertension (CTEPH), focusing on the improvement of functional class and right ventricular (RV) pressure. MATERIALS AND METHODS: Clinical data of patients with CTEPH were obtained from Yonsei Hospital between May 2012 and December 2021, and reviewed retrospectively. Twenty-six patients underwent endoscope-guided PEA during the study period, and the mean follow-up duration was 24.8±23.4 months. RESULTS: After PEA, most patients (88.5%) were weaned from inotropes without extracorporeal membrane oxygenation support during the first few days. Two patients (7.6%) had cerebrovascular accidents without neurological deficits. On echocardiography, the RV systolic pressure and tricuspid regurgitation grades significantly improved (p<0.001). Furthermore, the mean left ventricle end-diastolic diameter was significant increased (p=0.003), and the left ventricular end-systolic diameter increased (p<0.001). The median intensive care unit stay was 3.0±9.4 days, and median hospital stay 16.0±26.5 days. The 5-year survival rate was 95.5%, and the 5-year freedom rate of cardiac death was 100%. There was a marked improvement in New York Heart Association (NYHA) status (p<0.001). Cox regression suggested that the main pulmonary artery (MPA) involvement is a significant predictor of non-improvement in functional class post-PEA. CONCLUSION: Mortality rates are low and patients experience a marked improvement in NYHA class and health status after PEA. Moreover, MPA involvement may affect functional outcomes.


Assuntos
Hipertensão Pulmonar , Embolia Pulmonar , Humanos , Hipertensão Pulmonar/cirurgia , Hipertensão Pulmonar/etiologia , Estudos Retrospectivos , Resultado do Tratamento , Embolia Pulmonar/cirurgia , Artéria Pulmonar/cirurgia , Endarterectomia/efeitos adversos , Doença Crônica
10.
J Neuroradiol ; 50(1): 54-58, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35364131

RESUMO

PURPOSE: Antiplatelet maintenance after stent-assisted coil embolization (SACE) is generally considered essential to avoid post-procedural thromboembolic complications. However, there is still debate as to whether it is safe to discontinue antiplatelet drugs after SACE or when is the best time to do so. We investigate herein the clinical outcomes experienced by patients who discontinue antiplatelet agents after SACE. METHODS: From a prospective database, we retrieved the data for 120 consecutive patients (harboring 130 aneurysms) in whom antiplatelet agents were discontinued after SACE between January 2010 and December 2019. We defined thromboembolic complications associated with discontinuation as neurologic or radiographic ischemia that occurred within 6 months of discontinuation of antiplatelet agents; the lesion was required to be correlated with the stented artery. RESULTS: The mean time of discontinuation of antiplatelet medication was 31.4 ± 18.3 months after SACE (median, 26 months). The majority of patients stopped antiplatelet medication between 18 and 36 months after SACE (74 patients, 61.6%). Laser-cut closed-cell stent was most commonly applied in 91 aneurysms (70.0%), followed by braided closed-cell (n=29; 22.3 %) and laser-cut open-cell stent 10 (7.7 %). No patients experienced cerebral ischemia related to discontinuation of antiplatelet medication. CONCLUSION: Our preliminary study suggests that it may be safe to discontinue antiplatelet medication after SACE in patients at low risk for ischemia. The optimal time to discontinue might be around 18 to 36 months after SACE. Large cohort-based studies or randomized clinical trials are warranted to confirm these results.


Assuntos
Isquemia Encefálica , Embolização Terapêutica , Aneurisma Intracraniano , Tromboembolia , Humanos , Inibidores da Agregação Plaquetária/efeitos adversos , Aneurisma Intracraniano/terapia , Aneurisma Intracraniano/tratamento farmacológico , Stents/efeitos adversos , Estudos de Coortes , Isquemia Encefálica/etiologia , Embolização Terapêutica/efeitos adversos , Embolização Terapêutica/métodos , Estudos Retrospectivos , Resultado do Tratamento
11.
Small ; 18(48): e2205057, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36269881

RESUMO

Flat metasurfaces with subwavelength meta-atoms can be designed to manipulate the electromagnetic parameters of incident light and enable unusual light-matter interactions. Although hydrogel-based metasurfaces have the potential to control optical properties dynamically in response to environmental conditions, the pattern resolution of these surfaces has been limited to microscale features or larger, limiting capabilities at the nanoscale, and precluding effective use in metamaterials. This paper reports a general approach to developing tunable plasmonic metasurfaces with hydrogel meta-atoms at the subwavelength scale. Periodic arrays of hydrogel nanodots with continuously tunable diameters are fabricated on silver substrates, resulting in humidity-responsive surface plasmon polaritons (SPPs) at the nanostructure-metal interfaces. The peaks of the SPPs are controlled reversibly by absorbing or releasing water within the hydrogel matrix, the matrix-generated plasmonic color rendering in the visible spectrum. This work demonstrates that metasurfaces designed with these spatially patterned nanodots of varying sizes benefit applications in anti-counterfeiting and generate multicolored displays with single-nanodot resolution. Furthermore, this work shows system versatility exhibited by broadband beam-steering on a phase modulator consisting of hydrogel supercell units in which the size variations of constituent hydrogel nanostructures engineer the wavefront of reflected light from the metasurface.


Assuntos
Hidrogéis , Nanoestruturas , Prata , Umidade , Água
12.
Artigo em Inglês | MEDLINE | ID: mdl-35929988

RESUMO

A novel bacterium, designated strain JHSY0214T, was isolated from the gut of a Korean limpet, Cellana toreuma. Cells of strain JHSY0214T were Gram-stain-negative, strictly aerobic, yellow-pigmented, non-spore-forming, non-motile and showed a rod-coccus growth cycle. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain belonged to the genus Parasphingorhabdus, and was most closely related to Parasphingorhabdus litoris KCTC 12764T (98.71 %). Strain JHSY0214T had two fluoroquinolone-resistance genes and seven multidrug-resistance efflux pump genes, but did not have beta-lactamase genes and zinc resistance genes compared with P. litoris KCTC 12764T. Strain JHSY0214T grew optimally at 30 °C, pH 7.0 and in the presence of 2 % (w/v) NaCl. The predominant cellular fatty acids of strain JHSY0214T were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c; 41.2 %), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c; 21 %) and C16 : 0 (18.9 %). The major isoprenoid quinone was ubiquinone-10. The major polar lipids were sphingoglycolipid and phosphatidylethanolamine. The genomic DNA G+C content was 52.8 mol%. Based on phylogenetic, genotypic and phenotypic data, strain JHSY0214T represents a novel species of the genus Parasphingorhabdus, for which the name Parasphingorhabdus cellanae is proposed. The type strain is JHSY0214T (=KCTC 82387T=DSM 112279T).


Assuntos
Ácidos Graxos , Gastrópodes , Animais , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Filogenia , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA , Ubiquinona/química
13.
Anim Microbiome ; 4(1): 30, 2022 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-35527289

RESUMO

BACKGROUND: Invertebrates are a very attractive subject for studying host-microbe interactions because of their simple gut microbial community and host diversity. Studying the composition of invertebrate gut microbiota and the determining factors is essential for understanding their symbiotic mechanism. Cephalopods are invertebrates that have similar biological properties to vertebrates such as closed circulation system, an advanced nervous system, and a well-differentiated digestive system. However, it is not currently known whether their microbiomes have more in common with vertebrates or invertebrates. This study reports on the microbial composition of six cephalopod species and compares them with other mollusk and marine fish microbiomes to investigate the factors that shape the gut microbiota. RESULTS: Each cephalopod gut consisted of a distinct consortium of microbes, with Photobacterium and Mycoplasma identified as core taxa. The gut microbial composition of cephalopod reflected their host phylogeny, the importance of which was supported by a detailed oligotype-level analysis of operational taxonomic units assigned to Photobacterium and Mycoplasma. Photobacterium typically inhabited multiple hosts, whereas Mycoplasma tended to show host-specific colonization. Furthermore, we showed that class Cephalopoda has a distinct gut microbial community from those of other mollusk groups or marine fish. We also showed that the gut microbiota of phylum Mollusca was determined by host phylogeny, habitat, and diet. CONCLUSION: We have provided the first comparative analysis of cephalopod and mollusk gut microbial communities. The gut microbial community of cephalopods is composed of distinctive microbes and is strongly associated with their phylogeny. The Photobacterium and Mycoplasma genera are core taxa within the cephalopod gut microbiota. Collectively, our findings provide evidence that cephalopod and mollusk gut microbiomes reflect host phylogeny, habitat, and diet. It is hoped that these data can contribute to future studies on invertebrate-microbe interactions.

14.
J Microbiol ; 60(6): 576-584, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35437627

RESUMO

Three aerobic, Gram-negative, and rod-shaped bacterial strains, designated strains G4M1T, SM13T, and L12M9T, were isolated from the gut of Batillaria multiformis, Cellana toreuma, and Patinopecten yessoensis collected from the Yellow Sea in South Korea. All the strains grew optimally at 25°C, in the presence of 2% (w/v) NaCl, and at pH 7. These three strains, which belonged to the genus Polaribacter in the family Flavobacteriaceae, shared < 98.8% in 16S rRNA gene sequence and < 86.68% in whole-genome sequence with each other. Compared with the type strains of Polaribacter, isolates showed the highest sequence similarity to P. haliotis KCTC 52418T (< 98.68%), followed by P. litorisediminis KCTC 52500T (< 98.13%). All the strains contained MK-6 as their predominant menaquinone and iso-C15:0 as their major fatty acid. Moreover, all the strains had phosphatidylethanolamine as their polar lipid component. In addition, strain G4M1T had two unidentified lipids and three unidentified aminolipids, strain SM13T had three unidentified lipids and three unidentified aminolipids, and strain L12M9T had three unidentified lipids and one unidentified aminolipid. The DNA G + C contents of strains G4M1T, SM13T, and L12M9T were 31.0, 30.4, and 29.7 mol%, respectively. Based on phenotypic, phylogenetic, chemotaxonomic, and genotypic findings, strains G4M1T (= KCTC 82388T = DSM 112372T), SM13T (= KCTC 82389T = DSM 112373T), and L12M9T (= KCTC 62751T = DSM 112374T) were classified into the genus Polaribacter as the type strains of novel species, for which the names Polaribacter batillariae sp. nov., Polaribacter cellanae sp. nov., and Polaribacter pectinis sp. nov., respectively, have been proposed.


Assuntos
Flavobacteriaceae , Água do Mar , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Pectinidae , Filogenia , RNA Ribossômico 16S/genética , Água do Mar/microbiologia , Análise de Sequência de DNA , Frutos do Mar , Vitamina K 2/química
15.
Rev Sci Instrum ; 93(2): 023302, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-35232126

RESUMO

Fundamental obstacles toward the development of a portable time-of-flight mass spectrometer (TOF MS) are ionization sources and vacuum systems. To overcome these, a cold electron source (CES) and a pulse valve are introduced in this study to examine the possibility of developing a portable TOF MS. The CES is developed using a microchannel plate electron multiplier radiated by ultraviolet photons from a light-emitting diode. The CES is controlled using short pulses to generate accelerated electrons that ionize a substrate surface. A 10 ns CES pulse produces an electron flux density of 1013 to 1014 m-2 on the surface, and the short pulse minimizes the ionization time such that the resolution limit associated with a short drift tube is overcome. In addition, the injected 0.05 m3 quantitative sample reduces the vacuum exhaust load, and simultaneously, it is possible to temporarily form layers of the target molecules on the substrate. The possibility of immediate measurement by directly injecting benzene at ambient pressure was verified through repeated measurements; therefore, it is technically possible to use a CES to allow for a highly compact (and portable) TOF MS.

16.
Materials (Basel) ; 15(6)2022 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-35329735

RESUMO

To develop highly efficient thermoelectric materials, the generation of homogeneous heterostructures in a matrix is considered to mitigate the interdependency of the thermoelectric compartments. In this study, Cu2Te nanoparticles were introduced onto Bi2Te2.7Se0.3 n-type materials and their thermoelectric properties were investigated in terms of the amount of Cu2Te nanoparticles. A homogeneous dispersion of Cu2Te nanoparticles was obtained up to 0.4 wt.% Cu2Te, whereas the Cu2Te nanoparticles tended to agglomerate with each other at greater than 0.6 wt.% Cu2Te. The highest power factor was obtained under the optimal dispersion conditions (0.4 wt.% Cu2Te incorporation), which was considered to originate from the potential barrier on the interface between Cu2Te and Bi2Te2.7Se0.3. The Cu2Te incorporation also reduced the lattice thermal conductivity, and the dimensionless figure of merit ZT was increased to 0.75 at 374 K for 0.4 wt.% Cu2Te incorporation compared with that of 0.65 at 425 K for pristine Bi2Te2.7Se0.3. This approach could also be an effective means of controlling the temperature dependence of ZT, which could be modulated against target applications.

17.
Int J Sex Health ; 34(4): 658-664, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-38596393

RESUMO

Objective: This study assesses the impact of the SARS-CoV-2 (COVID-19) pandemic on the first time Korean adolescents have sex. Methods: The study examines 2017-2021 data from an annual, cross-sectional survey. Results: There is a significant drop in the percentages of male adolescents initiating sexual intercourse in 2020 and noticeable rebounds in 2021. However, the sexual debut among female students shows no significant change. Conclusions: We suggest that strict social distancing measures in 2020 and loosening of them in 2021, different orientations toward having sex by gender, and a strong sexual double standard are responsible for these findings.

18.
Int J Syst Evol Microbiol ; 71(12)2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34870576

RESUMO

Cultivation and isolation of gut bacteria are necessary for understanding their role in the intestinal ecosystem. We isolated a novel bacterium, designated strain BG01T, from the faeces of a patient with Crohn's disease. Strain BG01T was a strictly anaerobic, rod-shaped, Gram-variable and endospore-forming bacterium. Strain BG01T possessed C12 : 0, C18 : 0 dimethyl aldehyde (DMA) and C18 : 1 ω9c DMA as predominant cellular fatty acids and meso-diaminopimelic acid as a diagnostic diamino acid. Strain BG01T grew at 15-45 °C (optimum, 37 °C), with 0-4 % (w/v) NaCl (optimum, 0-1 %), at pH 6-10 (optimum, pH 7) and was resistant to bile salt, but not to ampicillin, metronidazole, vancomycin and cefoperazone. Butyrate, propionate, oxalacetate and fumarate were produced as fermentation end products from Gifu anaerobic medium broth. Strain BG01T showed 97.7 % 16S rRNA gene sequence similarity, and 92.0 and 48.5 % of average nucleotide identity and digital DNA-DNA hybridization values, respectively, with Anaerostipes caccae KCTC 15019T. Genomic analysis indicated that strain BG01T had a butyrate-producing pathway. The genomic G+C content of the strain was 43.5 mol%. Results of the phenotypic, phylogenetic and genotypic analyses indicated that strain BG01T represents a novel butyrate-producing species of the genus Anaerostipes, for which the name Anaerostipes hominis sp. nov. is proposed. The type strain is BG01T (=KCTC 15617T=JCM 32275T).


Assuntos
Butiratos/metabolismo , Doença de Crohn , Firmicutes/classificação , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , Doença de Crohn/microbiologia , DNA Bacteriano/genética , Ácidos Graxos/química , Fezes/microbiologia , Firmicutes/isolamento & purificação , Humanos , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
19.
Materials (Basel) ; 14(24)2021 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-34947161

RESUMO

One means of enhancing the performance of thermoelectric materials is to generate secondary nanoprecipitates of metallic or semiconducting properties in a thermoelectric matrix, to form proper band bending and, in turn, to induce a low-energy carrier filtering effect. However, forming nanocomposites is challenging, and proper band bending relationships with secondary phases are largely unknown. Herein, we investigate the in situ phase segregation behavior during melt spinning with various metal elements, including Ti, V, Nb, Mo, W, Ni, Pd, and Cu, in p-type Bi0.5Sb1.5Te3 (BST) thermoelectric alloys. The results showed that various metal chalcogenides were formed, which were related to the added metal elements as secondary phases. The electrical conductivity, Seebeck coefficient, and thermal conductivity of the BST composite with various secondary phases were measured and compared with those of pristine BST alloys. Possible band alignments with the secondary phases are introduced, which could be utilized for further investigation of a possible carrier filtering effect when forming nanocomposites.

20.
J Microbiol ; 59(11): 978-987, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34570338

RESUMO

Phenotypic and genomic analyses were performed to characterize two novel species, H23M54T and AMA3305T, isolated from the faeces of the Oriental stork (Ciconia boyciana) and the cinereous vulture (Aegypius monachus), respectively. Strains H23M54T and AMA3305T showed the highest similarities of 16S rRNA gene sequences and complete genome sequences with Ornithinimicrobium cavernae CFH 30183T (98.5% of 16S rRNA gene sequence similarity and 82.1% of average nucleotide identity, ANI) and O. pekingense DSM 21552T (98.5% of 16S rRNA gene sequence similarity and 82.3% of ANI), respectively. Both strains were Gram-stain-positive, obligate aerobes, non-motile, non-spore-forming, and coccoid- and rodshaped. Strain H23M54T grew optimally at 25-30°C and pH 8.0 and in the presence of 1.5-2% (wt/vol) NaCl, while strain AMA3305T grew optimally at 30°C and pH 7.0 and in the presence of 1-3% (wt/vol) NaCl. Both strains had iso-C15:0, iso-C16:0, and summed feature 9 (iso-C17:1ω9c and/or C16:0 10-methyl) as major cellular fatty acids. MK-8 (H4) was identified as the primary respiratory quinone in both strains. Strains H23M54T and AMA3305T possessed diphosphatidylglycerol and phosphatidylglycerol as major polar lipids. Moreover, strains H23M54T and AMA3305T commonly contained ribose and glucose as major sugars and L-ornithine, L-alanine, glycine, and aspartic acid as major amino acids. The polyphasic taxonomic data indicate that strains H23M54T and AMA3305T represent novel species of the genus Ornithinimicrobium. We propose the names Ornithinimicrobium ciconiae sp. nov. and Ornithinimicrobium avium sp. nov. for strains H23M54T (= KCTC 49151T = JCM 33221T) and AMA3305T (= KCTC 49180T = JCM 32873T), respectively.


Assuntos
Actinobacteria/isolamento & purificação , Aves/microbiologia , Fezes/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/metabolismo , Animais , Técnicas de Tipagem Bacteriana , Aves/classificação , DNA Bacteriano/genética , Espécies em Perigo de Extinção , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Filogenia , RNA Ribossômico 16S/genética
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