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1.
J Phys Chem Lett ; : 3528-3534, 2021 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33797241

RESUMO

Assembling p orbital ferromagnetic half-metallicity and a topological element, such as a Dirac point at the Fermi level, in a single nanomaterial is of particular interest for long-distance, high-speed, and spin-coherent transportation in nanoscale spintronic devices. On the basis of the tight-binding model, we present an orbital design of a two-dimensional (2D) anionogenic Dirac half-metal (ADHM) by patterning cations with empty d orbitals and anions with partially filled p-type orbitals into a kagome lattice. Our first-principles calculations show that 2D transition-metal peroxides h-TM2(O2)3 (TMO3, TM = Ti, Zr, Hf), containing group IVB transition-metal cations [TM]4+ bridged with dioxygen anions [O2]8/3- in a kagome structure, are stable ADHMs with a Curie temperature over 103 K. The 2/3 filled π* orbitals of dioxygen anions are ferromagnetically coupled, leading to p orbital ferromagnetism and a half-metallic Dirac point right at the Fermi level with a Fermi velocity reaching 2.84 × 105 m/s. We proposed that 2D h-TM2(O2)3 crystals may be extracted from ABO3 bulk materials containing 2D TMO3 layers.

2.
Sci Adv ; 7(10)2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33658198

RESUMO

One of the ultimate goals of analytic chemistry is to efficiently discriminate between amino acids. Here we demonstrate this ability using a single-molecule electrical methodology based on molecular nanocircuits formed from stable graphene-molecule-graphene single-molecule junctions. These molecular junctions are fabricated by covalently bonding a molecular machine featuring a permethylated-ß-cyclodextrin between a pair of graphene point contacts. Using pH to vary the type and charge of the amino acids, we find distinct multimodal current fluctuations originating from the different host-guest interactions, consistent with theoretical calculations. These conductance data produce characteristic dwell times and shuttling rates for each amino acid, and allow accurate, statistical real-time, in situ measurements. Testing four amino acids and their enantiomers shows the ability to distinguish between them within a few microseconds, thus paving a facile and precise way to amino acid identification and even single-molecule protein sequencing.

3.
Medicine (Baltimore) ; 100(9): e25024, 2021 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-33655973

RESUMO

ABSTRACT: An irrational belief is the direct cause of negative emotions and behavioral disorders in patients with breast cancer. Thus, this article examines these patients' irrational beliefs, which helps improve the emotions and behavioral disorders of breast cancer patients. Chinese breast cancer patients have unique irrational beliefs due to the influence of Chinese traditional culture. To understand the irrational beliefs surrounding breast cancer diagnosis in young Chinese patients, we conducted an interpretative phenomenological study.Semi-structured interviews were conducted in young Chinese breast cancer patients. According to Colaizzi method modified by Edward and Welsh, transcribed interviews were analyzed to understand patients' irrational beliefs. Based on the theoretical framework, this study adopted interpretative phenomenology. Interpretive description was used to construct participants' experiences of irrational beliefs. Thematic sufficiency was confirmed after 17 interviews.Owing to the lack of knowledge about breast cancer, all participants were more susceptible to traditional Chinese culture, empiric theory, family reassurance, and healthcare providers' behaviors, leading to patients' irrational beliefs, negative emotions, and behavioral disorders.This research confirms that irrational beliefs in young Chinese breast cancer patients are profoundly influenced by traditional Chinese culture. Chinese healthcare providers can use this information to provide targeted nursing, supportive services, and research, and help women identify their beliefs and understand how these beliefs affect their health.


Assuntos
Neoplasias da Mama/diagnóstico , Cultura , Emoções/fisiologia , Inquéritos e Questionários , Adulto , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/psicologia , China/epidemiologia , Feminino , Humanos , Morbidade/tendências
4.
Brain Stimul ; 14(3): 503-510, 2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33581283

RESUMO

OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) has been widely used in non-invasive treatments for different neurological disorders. Few biomarkers are available for treatment response prediction. This study aims to analyze the correlation between changes in long-term potentiation (LTP)-like cortical plasticity and cognitive function in patients with Alzheimer's disease (AD) that underwent rTMS treatment. METHODS: A total of 75 AD patients were randomized into either 20 Hz rTMS treatment at the dorsolateral prefrontal cortex (DLPFC) group (n = 37) or a sham treatment group (n = 38) for 30 sessions over six weeks (five days per week) with a three-month follow-up. Neuropsychological assessments were conducted using the Mini-Mental State Examination (MMSE) and Alzheimer's Disease Assessment-Cognitive Component (ADAS-Cog). The cortical plasticity reflected by the motor-evoked potential (MEP) before and after high-frequency repetitive TMS to the primary motor cortex (M1) was also examined prior to and after the treatment period. RESULTS: The results showed that the cognitive ability of patients who underwent the MMSE and ADAS-Cog assessments showed small but significant improvement after six weeks of rTMS treatment compared with the sham group. The cortical plasticity improvement correlated to the observed cognition change. CONCLUSIONS: Cortical LTP-like plasticity could predict the treatment responses of cognitive improvements in AD patients receiving rTMS intervention. This warrants future clinical trials using cortical LTP as a predictive marker.

5.
Microb Cell Fact ; 20(1): 28, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33531006

RESUMO

BACKGROUND: Norvancomycin has been widely used in clinic to treat against MRSA (Methicillin-resistant Staphylococcus aureus) and MRSE (Methicillin-resistant Staphylococcus epidermidis) infections in China. Amycolatopsis orientalis NCPC 2-48, a high yield strain derived from A. orientalis CPCC 200066, has been applied in industrial large-scale production of norvancomycin by North China Pharmaceutical Group. However, the potential high-yield and regulatory mechanism involved in norvancomycin biosynthetic pathway has not yet been addressed. RESULTS: Here we sequenced and compared the genomes and transcriptomes of A. orientalis CPCC 200066 and NCPC 2-48. These two genomes are extremely similar with an identity of more than 99.9%, and no duplication and structural variation was found in the norvancomycin biosynthetic gene cluster. Comparative transcriptomic analysis indicated that biosynthetic genes of norvancomycin, as well as some primary metabolite pathways for the biosynthetic precursors of norvancomycin were generally upregulated. AoStrR1 and AoLuxR1, two cluster-situated regulatory genes in norvancomycin cluster, were 23.3-fold and 5.8-fold upregulated in the high yield strain at 48 h, respectively. Over-expression of AoStrR1 and AoLuxR1 in CPCC 200066 resulted in an increase of norvancomycin production, indicating their positive roles in norvancomycin biosynthesis. Furthermore, AoStrR1 can regulate the production of norvancomycin by directly interacting with at least 8 promoters of norvancomycin biosynthetic genes or operons. CONCLUSION: Our results suggested that the high yield of NCPC 2-48 can be ascribed to increased expression level of norvancomycin biosynthetic genes in its cluster as well as the genes responsible for the supply of its precursors. The norvancomycin biosynthetic genes are presumably regulated by AoStrR1 and AoLuxR1, of them AoStrR1 is possibly the ultimate pathway-specific regulator for the norvancomycin production. These results are helpful for further clarification of the holistic and pathway-specific regulatory mechanism of norvancomycin biosynthesis in the industrial production strain.

6.
Food Chem Toxicol ; 149: 111970, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33421459

RESUMO

Studies have shown that the central renin-angiotensin system is involved in neurological disorders. Our previous studies have demonstrated that angiotensin II receptor type 1 (AT1R) in the brain could be a potential target against methamphetamine (METH) use disorder. The present study was designed to investigate the underlying mechanisms of the inhibitory effect of AT1R on various behavioural effects of METH. We first examined the effect of AT1R antagonist, candesartan cilexetil (CAN), on behavioural and neurotoxic effects of METH. Furthermore, we studied the role of phospholipase C beta 1 (PLCß1) blockade behavioural and neurotoxic effects of METH. The results showed that CAN significantly attenuated METH-induced behavioral disorders and neurotoxicity associated with increased oxidative stress. AT1R and PLCß1 were significantly upregulated in vivo and in vitro. Inhibition of PLCß1 effectively alleviated METH-induced neurotoxicity and METH self-administration (SA) by central blockade of the PLCß1 involved signalling pathway. PLCß1 blockade significantly decreased the reinforcing and motivation effects of METH. PLCß1 involved signalling pathway, as well as a more specific role of PLCß1, involved the inhibitory effects of CAN on METH-induced behavioural dysfunction and neurotoxicity. Collectively, our findings reveal a novel role of PLCß1 in METH-induced neurotoxicity and METH use disorder.

7.
Mol Psychiatry ; 26(2): 383-395, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33432190

RESUMO

The GABAB receptor (GABABR) agonist baclofen has been used to treat alcohol and several other substance use disorders (AUD/SUD), yet its underlying neural mechanism remains unclear. The present study aimed to investigate cortical GABABR dynamics following chronic alcohol exposure. Ex vivo brain slice recordings from mice chronically exposed to alcohol revealed a reduction in GABABR-mediated currents, as well as a decrease of GABAB1/2R and G-protein-coupled inwardly rectifying potassium channel 2 (GIRK2) activities in the motor cortex. Moreover, our data indicated that these alterations could be attributed to dephosphorylation at the site of serine 783 (ser-783) in GABAB2 subunit, which regulates the surface expression of GABABR. Furthermore, a human study using paired-pulse-transcranial magnetic stimulation (TMS) analysis further demonstrated a reduced cortical inhibition mediated by GABABR in patients with AUD. Our findings provide the first evidence that chronic alcohol exposure is associated with significantly impaired cortical GABABR function. The ability to promote GABABR signaling may account for the therapeutic efficacy of baclofen in AUD.

8.
Nano Lett ; 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33411541

RESUMO

Synthesis of the unconventional phase of noble metal nanocrystals may create new opportunities in exploring intriguing physicochemical properties but remains challenging. In the research field of thin film growth, the interface strain offers a general driving force to stabilize the metastable phase of epitaxial film. Herein we extend this concept to the field of noble metal nanocrystals and report the solution synthesis of metastable face-centered tetragonal Au that has not been discovered before. The successful synthesis relies on the formation of intermetallic AuCu3@Au core-shell structure, where the interface strain stabilizes the metastable fct Au overlayer. Compared with the face-centered cubic Au counterpart, the metastable fct Au shows greatly improved catalytic activity toward CO2 reduction to CO. The density functional theory calculations and spectroscopic studies reveal that the metastable fct Au upshifts the d-band center, which lowers the energy barrier of key intermediate COOH* formation and thus facilitates the reaction kinetics.

9.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 38(1): 47-51, 2021 Jan 10.
Artigo em Chinês | MEDLINE | ID: mdl-33423257

RESUMO

OBJECTIVE: To detect the mutation site in a pedigree affected with autosomal dominant polycystic kidney disease (ADPKD) and verify its impact on the protein function. METHODS: Peripheral blood samples were collected from the proband and his pedigree members for the extraction of genomic DNA. Mutational analysis was performed on the proband through whole-exome sequencing. Suspected variant was verified by Sanger sequencing. A series of molecular methods including PCR amplification, restriction enzyme digestion, ligation and transformation were also used to construct wild-type and mutant eukaryotic expression vectors of the PKD2 gene, which were transfected into HEK293T and HeLa cells for the observation of protein expression and cell localization. RESULTS: The proband was found to harbor a c.2051dupA (p. Tyr684Ter) frame shift mutation of the PKD2 gene, which caused repeat of the 2051st nucleotide of its cDNA sequence and a truncated protein. Immunofluorescence experiment showed that the localization of the mutant protein within the cell was altered compared with the wild-type, which may be due to deletion of the C-terminus of the PKD2 gene. CONCLUSION: The c.2051dupA (p. Tyr684Ter) mutation of the PKD2 gene probably underlay the pathogenesis of ADPKD in this pedigree.


Assuntos
Mutação da Fase de Leitura , Rim Policístico Autossômico Dominante , Proteínas Quinases , Análise Mutacional de DNA , Feminino , Células HEK293 , Células HeLa , Humanos , Masculino , Linhagem , Rim Policístico Autossômico Dominante/genética , Rim Policístico Autossômico Dominante/fisiopatologia , Proteínas Quinases/genética , Transporte Proteico/genética , Sequenciamento Completo do Exoma
10.
JAMA Psychiatry ; 2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33263727

RESUMO

Importance: The genetic basis of bipolar disorder (BD) in Han Chinese individuals is not fully understood. Objective: To explore the genetic basis of BD in the Han Chinese population. Design, Setting, and Participants: A genome-wide association study (GWAS), followed by independent replication, was conducted to identify BD risk loci in Han Chinese individuals. Individuals with BD were diagnosed based on DSM-IV criteria and had no history of schizophrenia, mental retardation, or substance dependence; individuals without any personal or family history of mental illnesses, including BD, were included as control participants. In total, discovery samples from 1822 patients and 4650 control participants passed quality control for the GWAS analysis. Replication analyses of samples from 958 patients and 2050 control participants were conducted. Summary statistics from the European Psychiatric Genomics Consortium 2 (PGC2) BD GWAS (20 352 cases and 31 358 controls) were used for the trans-ancestry genetic correlation analysis, polygenetic risk score analysis, and meta-analysis to compare BD genetic risk between Han Chinese and European individuals. The study was performed in February 2020. Main Outcomes and Measures: Single-nucleotide variations with P < 5.00 × 10-8 were considered to show genome-wide significance of statistical association. Results: The Han Chinese discovery GWAS sample included 1822 cases (mean [SD] age, 35.43 [14.12] years; 838 [46%] male) and 4650 controls (mean [SD] age, 27.48 [5.97] years; 2465 [53%] male), and the replication sample included 958 cases (mean [SD] age, 37.82 [15.54] years; 412 [43%] male) and 2050 controls (mean [SD] age, 27.50 [6.00] years; 1189 [58%] male). A novel BD risk locus in Han Chinese individuals was found near the gene encoding transmembrane protein 108 (TMEM108, rs9863544; P = 2.49 × 10-8; odds ratio [OR], 0.650; 95% CI, 0.559-0.756), which is required for dendritic spine development and glutamatergic transmission in the dentate gyrus. Trans-ancestry genetic correlation estimation (ρge = 0.652, SE = 0.106; P = 7.30 × 10-10) and polygenetic risk score analyses (maximum liability-scaled Nagelkerke pseudo R2 = 1.27%; P = 1.30 × 10-19) showed evidence of shared BD genetic risk between Han Chinese and European populations, and meta-analysis identified 2 new GWAS risk loci near VRK2 (rs41335055; P = 4.98 × 10-9; OR, 0.849; 95% CI, 0.804-0.897) and RHEBL1 (rs7969091; P = 3.12 × 10-8; OR, 0.932; 95% CI, 0.909-0.956). Conclusions and Relevance: This GWAS study identified several loci and genes involved in the heritable risk of BD, providing insights into its genetic architecture and biological basis.

11.
Mol Med Rep ; 22(6): 5339-5347, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33174007

RESUMO

Wound healing is a complex physiological process in which fibrocytes serve a vital role. However, the mechanism underlying the recruitment of fibrocytes during wound healing remains largely unknown. The present study aimed to investigate whether endothelial cells are involved in the recruitment of fibrocytes in wound healing. To mimic the in vivo angiogenic process, a co­culture system consisting of endothelial cells and fibrocytes was achieved using a permeable Transwell co­culture system. The expression of chemokines produced by endothelial cells with or without co­culture was then measured using a gene chip. Based on the dataset from chip analysis, chemokine ligand 15 (CCL15) produced by endothelial cells was identified, which likely serves a regulatory role in mediating the transmigration of fibrocytes. Overexpression of CCL15 in endothelial cells or chemokine receptor 1 (CCR1) in fibrocytes promoted the transmigration of fibrocytes, whilst silencing the expression of CCL15 in endothelial cells or that of CCR1 in fibrocytes attenuated the transmigration of fibrocytes. Results from the present study suggested that the CCL15­CCR1 axis between endothelial cells and fibrocytes serves a vital role in mediating the recruitment of fibrocytes during wound healing.

12.
Gene ; : 145183, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33007371

RESUMO

In order to explore the influence of egg-laying regulatory genes on egg production in ducks at different laying stages, Pekin duck and Black Muscovy duck were used in this study, including early laying stage (20-30 weeks old), peak laying period (31-48 weeks old) and late laying stage (49-66 weeks old). Relative quantitative RT-PCR was used to detect the mRNA transcription level of selected egg-laying regulatory genes in the ovary tissues of ducks at different laying stages. Study shows: during the laying period of Pekin duck, ESR1, LRP1, IGF-1 and LHR were involved in the regulation of egg-laying, and the high expression of LRP1 in the late stage could inhibit egg production. Still, the expression products of the other three genes showed promoting effect. During the laying period of Black Muscovy duck, FSH, VLDLR, IGF-1, PRLR, LHR and LRP1 participated in the regulation of egg-laying, in which the expression products of the first five genes could promote egg production, while LRP1 showed inhibitory effect. Through our experiments, these data will provide strong theoretical support for the breeding of Pekin duck and Black Muscovy duck.

13.
Behav Neurol ; 2020: 1574816, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33029254

RESUMO

Objectives: Retina abnormalities are related to cognitive disorders in patients with Alzheimer's disease (AD). Retinal amyloid beta (Aß) can be labeled by curcumin. We measured Aß content in the cerebrum and retina of APPswe/PS1dE9 (APP) transgenic mice with early age to investigate the correlation between cerebrum and retina. Methods: APP mice and age-matched wild-type mice were investigated every month from age 2 months to 6 months to assess changes in Aß content in the retina and cerebrum. At the beginning of each month, mice were fed a curcumin diet (50 mg/kg/day) for 7 consecutive days. The Aß levels in the retina and cerebrum were measured by ELISAs. Correlations were identified between retinal and cerebral Aß contents using Pearson's correlation. Results: In the absence of curcumin, there was a significant correlation between Aß contents in the retina and cerebrum of APP mice (r = 0.7291, P = 0.0014). With increasing age, Aß-mediated degenerative change in the cerebrum (P < 0.001 in 5 months) and retina (P < 0.01 in 5 months) increased significantly. The inhibitory effect of curcumin on the Aß level was significant in the cerebrum (P < 0.001) and retina (P < 0.01) of older APP mice in the early stage of life. Conclusion: We observed a significant correlation between the Aß content in the retina and Aß content in the cerebrum of APP mice. Our data suggest an appropriate time to measure retinal Aß. Although curcumin can label Aß in the retina, it also suppresses Aß levels and weakens the degree of correlation between Aß in cerebrum and retina tissues.

14.
Materials (Basel) ; 13(19)2020 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-32987635

RESUMO

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO3 can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar.

15.
Neuropharmacology ; 179: 108268, 2020 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-32791084

RESUMO

BACKGROUNDS: Long-term depression (LTD) is a form of physiologic plasticity that is important for reversal learning and may be linked to major depression. Few studies have examined LTP-like plasticity in patients with depression. It is unclear if continuous theta burst stimulation (cTBS) induced LTD is altered in depression patients. METHODS: Here we recruited 29 healthy control subjects and 31 female patients with depression. We performed cTBS protocol on left motor cortex and employed motor evoked potentials (MEPs) response to measure LTD-like plasticity. Peripheral molecules were measured for correlation analyses to cortical plasticity. RESULTS: Our results revealed persistent LTD-like plasticity deficits in female patients with depression. LTD-like plasticity was impaired in patients with depression despite the fact that peripheral concentrations of BDNF were comparable to that of healthy subjects. CONCLUSIONS: Our findings provide evidence for impaired LTD-like plasticity in patients with depression which may be an important mechanism linked to the pathophysiology and treatment of this disorder.

16.
Artigo em Inglês | MEDLINE | ID: mdl-32791513

RESUMO

Genetic analyses for bipolar disorder (BD) have achieved prominent success in Europeans in recent years, whereas its genetic basis in other populations remains relatively less understood. We herein report that the leading risk locus for BD in European genome-wide association studies (GWAS), the single-nucleotide polymorphism (SNP) rs9834970 near TRANK1 at 3p22 region, is also genome-wide significantly associated with BD in a meta-analysis of four independent East Asian samples including 5748 cases and 65,361 controls (p = 2.27 × 10-8, odds ratio = 1.136). Expression quantitative trait loci (eQTL) analyses and summary data-based Mendelian randomization (SMR) analyses in multiple human brain samples suggest that lower TRANK1 mRNA expression is a principal BD risk factor explaining its genetic risk signals at 3p22. We also identified another SNP rs4789 in the 3' untranslated region (3'UTR) of TRANK1 showing stronger eQTL associations as well as genome-wide significant association with BD. Despite the relatively unclear neuronal function of TRANK1, our mRNA expression analyses in the human brains and in rat primary cortical neurons reveal that genes highly correlated with TRANK1 are significantly enriched in the biological processes related to dendritic spine, synaptic plasticity, axon guidance and circadian entrainment, and are also more likely to exhibit strong associations in psychiatric GWAS (e.g., the CACNA1C gene). Overall, our results support that TRANK1 is a potential BD risk gene. Further studies elucidating its roles in this illness are needed.

17.
Plant Sci ; 298: 110575, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32771139

RESUMO

Primary root is the basic component of root system and plays a key role in early seedling growth and survival in rice. However, the molecular mechanism of primary root elongation still needs to be well understood. Here, we showed that OsWOX4, a WUSCHEL-related homeobox (WOX) transcription factor, was involved in the primary root elongation in rice. Silencing of OsWOX4 by RNA interference (RNAi) greatly increased the primary root length, whereas its overexpression reduced primary root elongation significantly. Moreover, the size of meristem zone and epidermal cell length of mature zone in RNAi root tips were drastically enhanced, while they were reduced markedly in overexpression lines, in comparison with that of wild type. Further analysis showed that the accumulation of free IAA was slightly increased in RNAi roots, but drastically reduced in plants overexpressing OsWOX4. The expression of genes responsible for auxin biosynthesis and transport was also changed in OsWOX4 transgenic lines. Transient transcriptional activation and electrophoretic mobility shift assays showed that OsWOX4 directly regulated the transcription of OsAUX1 through binding to its promoter region. Collectively, our results indicated that OsWOX4 played a crucial role in the primary root elongation by regulating auxin transport, suggesting its importance in rice root system architecture.

18.
Chem Commun (Camb) ; 56(76): 11287-11290, 2020 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-32839790

RESUMO

Pyridinium ylides are usually considered nucleophiles that can undergo various reactions involving electron pairs. However, it was found that ylides resulting from deprotonation of N-alkyl-substituted pyridinium salts exhibit radical characters, with no discernable NMR signals but decent EPR spectra in both solution and the solid state. An observed correlation between lowered π* energy level of the pyridinium ring and increased EPR activity indicates that thermally induced electron-transfer processes could be involved, where the variable-temperature EPR spectrum indicates a singlet ground state and a thermally activated triplet state for the ylide. The fact that the high-resolution mass spectrum confirms the presence of oligomers of a less sterically hindered pyridinium ylide further points to a radical mechanism.

19.
Nanoscale Horiz ; 5(11): 1496-1499, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32844856

RESUMO

Developing simple nonmagnetic methods to efficiently control spin transport across magnetic metal-magnetic semiconductor contacts plays a key role in developing high-performance nano-spintronic devices, since a magnetic field is hard to apply locally. For this purpose, based on first principles calculations, we here propose a mechanical means for manipulating the spin transport across two-dimensional magnetic metal-magnetic semiconductor van der Waals contacts formed between representative metallic Fe3GeTe2 and semiconducting CrGeTe3/CrI3 nanosheets. For such contacts, there exist four spin resolved Schottky barriers, i.e. the n/p-type Schottky barriers in the up/down spin channels, in which the dominant transport spin channel, characterized by the lowest Schottky barrier, can be selectively switched by regulating the magnetic coupling between the magnetic metal and magnetic semiconductor via interfacial sliding. In this way, single spin channel ohmic contacts with reversible spin polarization have been realized.

20.
Shanghai Kou Qiang Yi Xue ; 29(2): 133-137, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-32626874

RESUMO

PURPOSE: To analyze the effect of porcelain layer thicknesses and substrates on color properties and translucency of IPS e.max LT porcelain laminate veneers used to restore tetracycline stained teeth. METHODS: Porcelain specimens with different core and veneer thickness (veneer/core thickness: 0.25 mm/0.25 mm, 0.50 mm/0.25 mm, 0.25 mm/0.50 mm, 0.50 mm/0.50 mm, and 0.25 mm/0.75 mm) were fabricated by heat-press layering technique. CIE L*a*b* parameters were measured under simulated tetracycline backgrounds and black and white backgrounds by a spectrophotometer, color differences ΔE001 between specimens on simulated tetracycline backgrounds and backgrounds themselves and ΔE002 between specimens on simulated tetracycline backgrounds and white background were calculated. The translucent parameter(TP) was also calculated. The data were submitted to statistical analysis with SPSS 17.0 software package. RESULTS: ΔE001 increased with increase of thickness of the core and veneer layer, but there was no significant difference between 0.25 mm and 0.50 mm core thickness groups with 0.50 mm veneer in thickness (P>0.01). Except for light grey, ΔE002 decreased over other substrates with increase of thickness of the core and veneer layer, but there was no significant difference between 0.50 mm and 0.75 mm core thickness groups with 0.25 mm veneer in thickness (P>0.01). Both ΔE001 and ΔE002 were significantly different over different substrates(P<0.01). TP decreased as the increase of core and veneer thickness and TP was significantly different with different core and veneer thickness(P<0.01). CONCLUSIONS: Both the core/veneer thickness and the substrate have significant influence on color matching and masking ability of IPS e.max LT porcelain laminate veneers used to restore tetracycline stained teeth. As for IPS e.max LT porcelain veneers, the color property was the best when yellowish tetracycline stained teeth were restored, while the light grey was worst. The thickness of core and veneer has significant influence on the translucency of porcelain laminate veneers.


Assuntos
Porcelana Dentária , Facetas Dentárias , Cerâmica , Cor , Teste de Materiais , Tetraciclina
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