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1.
Small ; : e2401537, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38822716

RESUMO

Metallic 1T-MoS2 with high intrinsic electronic conductivity performs Pt-like catalytic activity for hydrogen evolution reaction (HER). However, obtaining pure 1T-MoS2 is challenging due to its high formation energy and metastable properties. Herein, an in situ SO4 2--anchoring strategy is reported to synthesize a thin layer of 1T-MoS2 loaded on commercial carbon. Single Pd atoms, constituting a substantial loading of 7.2 wt%, are then immobilized on the 1T-phase MoS2 via Pd─S bonds to modulate the electronic structure and ensure a stable active phase. The resulting Pd1/1T-MoS2/C catalyst exhibits superior HER performance, featuring a low overpotential of 53 mV at the current density of 10 mA cm-2, a small Tafel slope of 37 mV dec-1, and minimal charge transfer resistance in alkaline electrolyte. Moreover, the catalyst also demonstrates efficacy in acid and neutral electrolytes. Atomic structural characterization and theoretical calculations reveal that the high activity of Pd1/1T-MoS2/C is attributed to the near-zero hydrogen adsorption energy of the activated sulfur sites on the two adjacent shells of atomic Pd.

2.
J Am Chem Soc ; 145(49): 26580-26591, 2023 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-38029332

RESUMO

The precise modulation of nanosheet stacking modes introduces unforeseen properties and creates momentous applications but remains a challenge. Herein, we proposed a strategy using bipolar molecules as torque wrenches to control the stacking modes of 2-D Zr-1,3,5-(4-carboxylphenyl)-benzene metal-organic framework (2-D Zr-BTB MOF) nanosheets. The bipolar phenyl-alkanes, phenylmethane (P-C1) and phenyl ethane (P-C2), predominantly instigated the rotational stacking of Zr-BTB-P-C1 and Zr-BTB-P-C2, displaying a wide angular distribution. This included Zr-BTB-P-C1 orientations at 0, 12, 18, and 24° and Zr-BTB-P-C2 orientations at 0, 6, 12, 15, 24, and 30°. With reduced polarity, phenyl propane (P-C3) and phenyl pentane (P-C5) introduced steric hindrance and facilitated alkyl hydrophobic interactions with the nanosheets, primarily resulting in the modulation of eclipsed stacking for Zr-BTB-P-C3 (64.8%) and Zr-BTB-P-C5 (93.3%) nanosheets. The precise angle distributions of four Zr-BTB-P species were in agreement with theoretical calculations. The alkyl induction mechanism was confirmed by the sequential guest replacement and 2-D 13C-1H heteronuclear correlation (HETCOR). In addition, at the single-particle level, we first observed that rotational stacked pores exhibited similar desorption rates for xylene isomers, while eclipsed stacked pores showed significant discrepancy for xylenes. Moreover, the eclipsed nanosheets as stationary phases exhibited high resolution, selectivity, repeatability, and durability for isomer separation. The universality was proven by another series of bipolar acetate-alkanes. This bipolar molecular torque wrench strategy provides an opportunity to precisely control the stacking modes of porous nanosheets.

3.
Zhonghua Nan Ke Xue ; 29(4): 323-330, 2023 Apr.
Artigo em Zh | MEDLINE | ID: mdl-38598216

RESUMO

OBJECTIVE: To investigate the difference in the levels of metabolites in the seminal plasma exosomes (SPE) of men with a high sperm DNA fragmentation index (DFI) from those with a low DFI. METHODS: We performed a sperm exosomal metabolomics analysis of 5 healthy married men with DFI ≤15% (the control group) and another 5 with DFI ≥30% and matched in marital status, age and body mass index with the controls (the case group). Using high-performance liquid chromatography and mass spectrum, we examined the metabolites, observed their difference, and analyzed the metabolite enrichment pathway by Kyoto encyclopedia of genes and genomes (KEGG). According to the inclusion and exclusion criteria, we also selected 11 men in the control group and 20 men in the case group, and detected the differences in the seminal plasma amino acid and carnitine between the two groups using liquid measurement systems. RESULTS: After primary and secondary analyses and qualified screening, 23 metabolites related to sperm DNA integrity were obtained, including 9 organic acids, 2 amino acid intermediate metabolites, and 11 acylcarnitine, purine, niacin and other intermediate products. KEGG enrichment analysis showed that 23 metabolites were mainly involved in the sphingoid signaling pathway, niacin and niacinamide metabolic pathway, and arginine and proline metabolic pathway. Further verification revealed no difference in the level of seminal plasma amino acid between the two groups, and significantly lower levels of seminal plasma acylcarnitine, free carnitine, propionylcarnitine, 3-hydroxybutyrylcarnitine and malonylcarnitine, 3-hydroxyisovalerylcarnitine and succinylcarnitine, and isoamyl (enylcarnitine) in the case group than in the controls (P<0.05). CONCLUSION: There are significant differences in the levels of the metabolites organic acids, amino acids and acylcarnitine in the SPE of males with a high DFI from those with a low DFI. The level of seminal plasma acylcarnitine is significantly correlated with sperm DFI, which can be used as an indicator in quantitative and rapid assessment of the degree of sperm DNA damage.


Assuntos
Carnitina/análogos & derivados , Exossomos , Niacina , Humanos , Masculino , Sêmen , Fragmentação do DNA , Espermatozoides , Aminoácidos
4.
Biochem Biophys Res Commun ; 637: 73-82, 2022 12 31.
Artigo em Inglês | MEDLINE | ID: mdl-36375253

RESUMO

Breast cancer is one of the most frequent malignancies in females. The molecular mechanism of how breast cancer development and recurrence still need to be explored. Peroxisome gamma coactivator-1ß (PGC-1ß) was engaged in cancer energy metabolism and tumor genesis. However, the mechanisms of PGC-1ß in breast cancer have not been fully understood. In this study, PCG-1ß overexpressed and knockdown vectors were transferred into MCF-7 cells. With the association-quantitative connection analysis, the different expressions of mRNAs and proteins were examined. Additionally, the terms on differentially expressed mRNAs and proteins were enriched by GO and KEGG. Based on the results, 1872 differentially expressed genes were identified in the up-regulated of PGC-1ß group, and 1318 genes were found in the down-regulated of PGC-1ß cells. With the label-free technique, 221 differentially expressed proteins were screened in PGC-1ß up-regulated group, and 459 proteins were identified in PGC-1ß down-regulated group. Correlation analysis showed that 49 significantly expressed mRNA-protein pairs in OV vs CT groups and 25 paired in SI vs CT groups. Combined analysis of transcriptome and proteome demonstrated that PGC-1ß plays a important role in cancer energy metabolism and boosting the pace of chemical processes in the proliferation of breast cancer cells. Additional investigation about PGC-1ß and energy metabolism in cancer cells may shed fresh light on the growth and treatment of breast cancer cells.


Assuntos
Neoplasias da Mama , Proteínas de Ligação a RNA , Feminino , Humanos , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Peroxissomos/metabolismo , RNA Mensageiro/genética , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Células MCF-7
5.
J Org Chem ; 87(6): 3978-3988, 2022 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-35254832

RESUMO

Nitrogen, phosphorus, and oxygen codoped carbon catalysts were successfully synthesized using dried yeast powder as a pyrolysis precursor. The yeast-derived heteroatom-doped carbon (yeast@C) catalysts exhibited outstanding performance in the oxidation of Csp3-H bonds to ketones and esters, giving excellent product yields (of up to 98% yield) without organic solvents at low O2 pressure (0.1 MPa). The catalytic oxidation protocol exhibited a broad range of substrates (38 examples) with good functional group tolerance, excellent regioselectivity, and synthetic utility. The yeast-derived heteroatom-doped carbon catalysts showed good reusability and stability after recycling six times without any significant loss of activity. Experimental results and DFT calculations proved the important role of N-oxide (N+-O-) on the surface of yeast@C and a reasonable carbon radical mechanism.


Assuntos
Nitrogênio , Fermento Seco , Carbono/química , Catálise , Nitrogênio/química , Oxigênio , Fósforo , Saccharomyces cerevisiae
6.
Fish Shellfish Immunol ; 124: 454-461, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35452833

RESUMO

The TIR domain-containing adaptor inducing IFN-ß (TRIF) is an adaptor molecule that plays a critical role in the Toll-like receptors (TLRs)-mediated innate immune signaling pathway. Lamprey, as the most primitive jawless vertebrate, rely mainly on innate immunity to defend against various pathogens infection. The function of TRIF in lamprey remains unknown. In this study, a homologous adaptor molecule TRIF, named LmTRIF, was identified in Northeast Chinese lamprey (Lethenteron morii). The LmTRIF coding sequence (cds) is 1242 bp in length and encodes 413 amino acids (aa). Domain analysis showed that LmTRIF is characterized with the classical TIR domain and a lack of TRAF6 binding motif. The results of evolutionary tree indicated that the relationship between LmTRIF and other homologous proteins was consistent with the position of lamprey in the species evolutionary history. The relative expression of LmTRIF was highest in the liver of larvae and in the gill of adults, respectively. Cellular immunofluorescence assays showed that LmTRIF was expressed in the cytoplasma in both mammalian cell line HEK 293T and the fish cell line EPC. The double luciferase reporter gene assay showed that the overexpression of LmTRIF promoted the activity of NF-κB, an immune transcription factor downstream of the classical TLR signaling pathway. In this study, we identified the TLR adaptor molecule TRIF from L. morii, a vertebrate more primitive than fish. Our results suggested an important role of LmTRIF in the innate immune signal transduction process of L. morii and is the basis for the origin and evolution of the TLR signaling pathway in the innate immune system in vertebrates.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular , Lampreias , Proteínas Adaptadoras de Transporte Vesicular/genética , Animais , China , Lampreias/genética , Lampreias/metabolismo , Mamíferos/metabolismo , NF-kappa B/metabolismo , Fatores de Transcrição/metabolismo
7.
Entropy (Basel) ; 24(6)2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35741526

RESUMO

We introduce a new incompatibility criterion for quantum channels based on the notion of (quantum) Fisher information. Our construction is based on a similar criterion for quantum measurements put forward by H. Zhu. We then study the power of the incompatibility criterion in different scenarios. First, we prove the first analytical conditions for the incompatibility of two Schur channels. Then, we study the incompatibility structure of a tuple of depolarizing channels, comparing the newly introduced criterion with the known results from asymmetric quantum cloning.

8.
Angew Chem Int Ed Engl ; 61(37): e202207786, 2022 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-35723492

RESUMO

Precise shaping of metal-organic frameworks (MOFs) is significant in both fundamental coordination chemistry and practical applications, such as catalysis, separation, and biomedicine. Herein, we demonstrated a linker scissoring strategy for precisely shaping MOFs through surface conformational pairing. In this strategy, the bidentate linkers which were designed according to the original tetratopic ligands and the coordination environment of MOF surfaces, were utilized as the covering agents. The shape of these covering agents and the surface conformation of metals onto MOFs restricted them to coordinate on specific MOF facets thus precisely controlling the shape of the MOFs. Different shapes of PCN-608 from nanoplate (PCN-NP) to nanorod (PCN-NR) have been targeted by adding different bidentate linkers. The universality of this strategy was demonstrated by controlling the shapes of the NU-MOFs from nanoplate to nanorod. This strategy provides a new guiding principle to synthesize MOF nanocrystals with controlled shapes.


Assuntos
Estruturas Metalorgânicas , Catálise , Cromatografia , Estruturas Metalorgânicas/química , Conformação Molecular
9.
Mol Hum Reprod ; 27(11)2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34590701

RESUMO

PIWI-interacting small RNAs (piRNAs) maintain genome stability in animal germ cells, with a predominant role in silencing transposable elements. Mutations in the piRNA pathway in the mouse uniformly lead to failed spermatogenesis and male sterility. By contrast, mutant females are fertile. In keeping with this paradigm, we previously reported male sterility and female fertility associated with loss of the enzyme HENMT1, which is responsible for stabilising piRNAs through the catalysation of 3'-terminal 2'-O-methylation. However, the Henmt1 mutant females were poor breeders, suggesting they could be subfertile. Therefore, we investigated oogenesis and female fertility in these mice in greater detail. Here, we show that mutant females indeed have a 3- to 4-fold reduction in follicle number and reduced litter sizes. In addition, meiosis-II mutant oocytes display various spindle abnormalities and have a dramatically altered transcriptome which includes a down-regulation of transcripts required for microtubule function. This down-regulation could explain the spindle defects observed with consequent reductions in litter size. We suggest these various effects on oogenesis could be exacerbated by asynapsis, an apparently universal feature of piRNA mutants of both sexes. Our findings reveal that loss of the piRNA pathway in females has significant functional consequences.


Assuntos
Fertilidade , Infertilidade Feminina/enzimologia , Meiose , Metiltransferases/metabolismo , Oócitos/enzimologia , Oogênese , RNA Interferente Pequeno/metabolismo , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Infertilidade Feminina/genética , Infertilidade Feminina/fisiopatologia , Metiltransferases/genética , Camundongos , RNA Interferente Pequeno/genética , Transcriptoma
10.
Hum Reprod ; 36(3): 771-784, 2021 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-33367783

RESUMO

STUDY QUESTION: Do mitochondria-targeted therapies reverse ageing- and oxidative stress-induced spindle defects in oocytes from mice and humans? SUMMARY ANSWER: Exposure to MitoQ or BGP-15 during IVM protected against spindle and chromosomal defects in mouse oocytes exposed to oxidative stress or derived from reproductively aged mice whilst MitoQ promoted nuclear maturation and protected against chromosomal misalignments in human oocytes. WHAT IS KNOWN ALREADY: Spindle and chromosomal abnormalities in oocytes are more prevalent with maternal aging, increasing the risk of aneuploidy, miscarriage and genetic disorders such as Down's syndrome. The origin of compromised oocyte function may be founded in mitochondrial dysfunction and increased reactive oxygen species (ROS). STUDY DESIGN, SIZE, DURATION: Oocytes from young and old mice were treated with MitoQ and/or BGP-15 during IVM. To directly induce mitochondrial dysfunction, oocytes were treated with H2O2, and then treated the MitoQ and/or BGP-15. Immature human oocytes were cultured with or without MitoQ. Each experiment was repeated at least three times, and data were analyzed by unpaired-sample t-test or chi-square test. PARTICIPANTS/MATERIALS, SETTING, METHODS: Immature germinal vesicle (GV) stage oocytes from 1-, 12- and 18-month-old mice were obtained from preovulatory ovarian follicles. Oocytes were treated with MitoQ and/or BGP-15 during IVM. GV-stage human oocytes were cultured with or without MitoQ. Mitochondrial membrane potential and mitochondrial ROS were measured by live-cell imaging. Meiotic spindle and chromosome alignments were visualized by immunofluorescent labeling of fixed oocytes and the 3-dimensional images were analyzed by Imaris. MAIN RESULTS AND THE ROLE OF CHANCE: MitoQ or BGP-15 during IVM protects against spindle and chromosomal defects in oocytes exposed to oxidative stress and in oocytes from aged mice (P < 0.001). In human oocytes, the presence of MitoQ during IVM promoted nuclear maturation and had a similar positive effect in protecting against chromosomal misalignments (P < 0.001). LIMITATIONS, REASONS FOR CAUTION: Our study identifies two excellent candidates that may help to improve fertility in older women. However, these potential therapies must be tested for efficacy in clinical IVM systems, and undergo thorough examination of resultant offspring in preclinical models before utilization. WIDER IMPLICATIONS OF THE FINDINGS: Our results using in-vitro systems for oocyte maturation in both mouse and human provide proof of principle that mitochondrially targeted molecules such as MitoQ and BGP-15 may represent a novel therapeutic approach against maternal aging-related spindle and chromosomal abnormalities. STUDY FUNDING/COMPETING INTEREST(S): The project was financially supported by the National Health and Medical Research Council and Australian Research Council, Australia. U.A.-Z. was supported by the Iraqi Higher Education and Scientific Research Ministry PhD scholarship and O.C. was supported by TUBITAK-1059B191601275. M.P.M. consults for MitoQ Inc. and holds patents in mitochondria-targeted therapies. R.L.R. is an inventor on patents relating to the use of BGP-15 to improve gamete quality. TRIAL REGISTRATION NUMBER: N/A.


Assuntos
Peróxido de Hidrogênio , Oócitos , Idoso , Animais , Austrália , Humanos , Peróxido de Hidrogênio/metabolismo , Técnicas de Maturação in Vitro de Oócitos , Camundongos , Mitocôndrias , Oócitos/metabolismo , Oximas , Piperidinas , Fuso Acromático
11.
Appl Opt ; 60(13): 3925-3935, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33983331

RESUMO

By combining the conformal polishing method with short stroke vibration, a novel, to the best of our knowledge, conformal vibration polishing (CVP) method is proposed. The CVP method is expected to be an efficient means of optical processing by its high material removal rate and smoothing characteristics of mid-spatial frequency (MSF) errors. A quantitative time-domain smoothing model and a convergence factor (${\rm CF}_C$) are presented based on the research of smoothing characteristics. The motion mechanism, material removal ability, solution, and expansion of the smoothing model are demonstrated theoretically and experimentally. The experimental results exhibited good agreement with the theoretical predictions for the proposed method. The research provides a certain theoretical foundation for parameter selection and process optimization of the CVP method.

12.
J Clin Ultrasound ; 49(8): 838-840, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33991347

RESUMO

X-linked hypohidrotic ectodermal dysplasia (XLHED) is a rare congenital genetic disorder caused by mutations in the ectodysplasin A gene, resulting in dysplasia or complete absence of teeth, hair, and sweat glands. XLHED is rarely diagnosed prenatally. We describe a case of XLHED diagnosed with prenatal sonography and umbilical cord blood gene testing.


Assuntos
Displasia Ectodérmica Anidrótica Tipo 1 , Displasia Ectodérmica , Displasia Ectodérmica/diagnóstico por imagem , Displasia Ectodérmica/genética , Displasia Ectodérmica Anidrótica Tipo 1/diagnóstico por imagem , Displasia Ectodérmica Anidrótica Tipo 1/genética , Feminino , Humanos , Mutação , Gravidez , Glândulas Sudoríparas , Ultrassonografia Pré-Natal
13.
Pak J Med Sci ; 37(5): 1382-1386, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34475916

RESUMO

OBJECTIVE: To investigate the relationship between left ventricular hypertrophy (LVH) and coronary artery disease in the very elderly (over 80 years old) patients with hypertension. METHODS: One hundred twenty cases of very elderly patients with hypertension admitted to our hospital from March 2018 to December 2020 were selected and divided into two groups: the LVH group and the non-LVH group, all of whom were older aged over 80 years, including 62 patients in the LVH group and 58 patients in the non-LVH group. All patients underwent cardiac color Doppler ultrasound examination, 24-hour dynamic ECG examination, and coronary angiography or coronary CTA examination. The clinical data of the two groups were analyzed statistically. RESULTS: There were significant differences in the number of diseased vessels, degree of coronary stenosis and vascular calcification between the two groups (P<0.05). Moreover, the results of risk factors for the degree of coronary artery disease in the two groups showed that the history of diabetes, 2hPG and LVH were independent risk factors for the three-vessel disease, while the history of LVH, FPG and alcohol intake were independent risk factors for diffuse lesions, but there was no statistical difference in the correlation between them and the degree of coronary stenosis. CONCLUSION: LVH is an independent risk factor for coronary artery stenosis and calcification in the very elderly patients with hypertension, but there is no statistical difference in the correlation between LVH and the degree of coronary stenosis.

14.
Angew Chem Int Ed Engl ; 60(13): 6920-6925, 2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33480119

RESUMO

The tuning of metal-organic framework (MOF) nanosheet stacking modes from molecular level was rarely explored although it significantly affected the properties and applications of nanosheets. Here, the different stacking modes of Zr-1, 3, 5-(4-carboxylphenyl)-benzene framework nanosheets were synthesized through the induction of different host-guest noncovalent interactions. The solvents of methyl benzene and ethyl acetate induced twisted stacking of nanosheets with the specific rotation angles of 12°, 18°, 24° and 6°, 18°, 24°, 30°, respectively, which was in agreement with theoretical calculations. Meanwhile, the alkanes were likely to vertically enter the pores of Zr-BTB nanosheets because of steric hindrance and hydrophobic interactions, resulting in the untwisted stacking of nanosheets. The untwisted ordered nanopores showed the excellent gas chromatographic separations of benzene derivative isomers, which was better than twisted nanosheets stacking and commercial columns. This work uncovers a rational strategy to control the stacking of two-dimensional MOF nanosheets.

15.
J Am Chem Soc ; 142(17): 7968-7975, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32266814

RESUMO

Ion migration has been recognized as a critical step in determining the performance of numerous devices in chemistry, biology, and material science. However, direct visualization and quantitative investigation of solid-phase ion migration among anisotropic nanostructures have been a challenging task. Here, we report an in-situ ChemTEM method to quantitatively investigate the solid-phase ion migration process among coassembled nanowires (NWs). This complicated process was tracked within a NW and between NWs with an obvious nanogap, which was revealed by both phase field simulation and ab initio modeling theoretical evaluation. A migration "bridge" between neighboring NWs was observed. Furthermore, these new observations could be applied to migration of other metal ions on semiconductor NWs. These findings provide critical insights into the solid-phase ion migration kinetics occurring in nanoscale systems with generality and offer an efficient tool to explore other ion migration processes, which will facilitate fabrication of customized and new heteronanostructures in the future.

16.
Appl Opt ; 59(12): 3619-3623, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32400486

RESUMO

Serious edge effects of potassium dihydrogen phosphate (${{\rm KH}_2}{{\rm PO}_4}$KH2PO4, KDP) manufactured using single-point diamond turning (SPDT) often result in disqualification of the transmittance wavefront for high-power laser systems. In this paper, based on the theoretical analysis of sucker hole configuration and the pressure distribution law under the vacuum chuck condition of crystal elements, the influence of sucker hole configuration on the transmittance wavefront root-mean-square gradient (GRMS) is verified through fly-cutting experiments. By adopting the newly designed vacuum chuck, the vacuum-chucking quality is effectively improved, and the edge effect is accordingly suppressed in the SPDT. Moreover, the accuracy of the transmittance wavefront GRMS has an improvement of about 25% under the same processing parameters.

17.
Water Sci Technol ; 82(5): 877-886, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031067

RESUMO

Water pollution from antibiotics has attracted a lot of attention for its serious threat to human health. In this study, a magnetic adsorbent (zinc ferrite/activated carbon (ZnFe2O4/AC) was synthesized via microwave method to effectively remove gemifioxacin mesylate (GEM) and moxifloxacin hydrochloride (MOX). Based on the porosity of AC and the magnetism of ZnFe2O4, the resulting ZnFe2O4/AC has high adsorption capacities and can be easily separated from the solid-liquid system via a magnetic field. The largest adsorption capacities for GEM and MOX can reach up to 433.4 mg g-1 and 388.8 mg g-1, respectively, higher than those of reported adsorbents such as MIL-101 and MOF-808. Fastest adsorptions of GEM and MOX were found at 5 min, and solution pH and coexisting salts do not have a significant influence on the adsorption process. The adsorption mechanism analysis indicates that electrostatic interaction and H-bond interaction contribute to the effective adsorption.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Adsorção , Antibacterianos , Magnetismo
18.
Nat Mater ; 17(1): 49-56, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29180776

RESUMO

Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO3 thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

19.
J Org Chem ; 84(22): 14892-14897, 2019 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-31475536

RESUMO

Three new monoterpenoid indole alkaloids (MIAs), hunterines A-C (1-3), were isolated from Hunteria zeylanica. Compound 1 possesses a unique skeleton with an unprecedented azabicyclo[4.3.1]decane ring system. Compounds 2 and 3 are a pair of epimeric vobasinylindole alkaloid heterodimers. Their structures including absolute configurations were established by spectroscopic analyses, X-ray diffraction, computational calculation, and the modified Mosher's method. Plausible biogenetic pathways of 1-3 were also proposed. Alkaloid 1 showed moderate cytotoxic activity against the HepG2 cell line.

20.
Mol Biol Rep ; 46(3): 3451-3460, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31012026

RESUMO

An isolate (CanS-34A) of Aspergillus from a healthy plant of oilseed rape (Brassica napus) was identified based on morphological characterization and multi-locus phylogeny using the sequences of internal transcribed spacer (ITS)-5.8S rDNA region, BenA (for ß-tubulin), CaM (for calmodulin) and RPB2 (for RNA polymerase II). The results showed that CanS-34A belongs to Aspergillus capensis Hirooka et al. The antifungal metabolites produced by CanS-34A in potato dextrose broth (PDB) were extracted with chloroform. Three antifungal metabolites were isolated and purified from the chloroform extract of the PDB cultural filtrates of CanS-34A, and chemically identified as methyl dichloroasterrate, penicillither and rosellichalasin. They all showed antifungal activity against the plant pathogenic fungi Botrytis cinerea, Monilinia fructicola, Sclerotinia sclerotiorum and Sclerotinia trifoliorum with the EC50 values ranging from 2.46 to 65.00 µg/mL. To our knowledge, this is the first report about production of penicillither by Aspergillus and about the antifungal activity of methyl dichloroasterrate, penicillither and rosellichalasin against the four plant pathogenic fungi.


Assuntos
Aspergillus/classificação , Aspergillus/metabolismo , Brassica napus/microbiologia , Antifúngicos/metabolismo , Ascomicetos/genética , Aspergillus/genética , Aspergillus/isolamento & purificação , Testes de Sensibilidade Microbiana , Filogenia
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