RESUMO
Heterostructures may exhibit completely new physical properties that may be otherwise absent in their individual component materials. However, how to precisely grow or assemble desired complex heterostructures is still a significant challenge. In this work, the collision dynamics of a carbon nanotube and a boron nitride nanotube under different collision modes were investigated using the self-consistent-charge density-functional tight-binding molecular dynamics method. The energetic stability and electronic structures of the heterostructure after collision were calculated using the first-principles calculations. Five main collision outcomes are observed, that is, two nanotubes can (1) bounce back, (2) connect, (3) fuse into a defect-free BCN heteronanotube with a larger diameter, (4) form a heteronanoribbon of graphene and hexagonal boron nitride and (5) create serious damage after collision. It was found that both the BCN single-wall nanotube and the heteronanoribbon created by collision are the direct band-gap semiconductors with the band gaps of 0.808 eV and 0.544 eV, respectively. These results indicate that collision fusion is a viable method to create various complex heterostructures with new physical properties.
Assuntos
Nanotubos de Carbono , Nanotubos de Carbono/química , Boro/química , Compostos de Boro/química , Simulação de Dinâmica MolecularRESUMO
The megajansky radio burst, FRB 20200428, and other bright radio bursts detected from the Galactic source SGR J1935+2154 suggest that magnetars can make fast radio bursts (FRBs), but the emission site and mechanism of FRB-like bursts are still unidentified. Here, we report the emergence of a radio pulsar phase of the magnetar 5 months after FRB 20200428. Pulses were detected in 16.5 hours over 13 days using the Five-hundred-meter Aperture Spherical radio Telescope, with luminosities of about eight decades fainter than FRB 20200428. The pulses were emitted in a narrow phase window anti-aligned with the x-ray pulsation profile observed using the x-ray telescopes. The bursts, conversely, appear in random phases. This dichotomy suggests that radio pulses originate from a fixed region within the magnetosphere, but bursts occur in random locations and are possibly associated with explosive events in a dynamically evolving magnetosphere. This picture reconciles the lack of periodicity in cosmological repeating FRBs within the magnetar engine model.
RESUMO
Lung cancer is a common cancer type, and has the highest mortality rate in the world. A genomewide association study suggests that the genetic marker rs9390123 is significantly associated with DNA repair capacity (DRC) in lung cancer. Analysis of the data derived from the 1000 Genomes Project indicated that there is another single nucleotide polymorphism (SNP), rs9399451, in strong linkage disequilibrium with rs9390123 in Caucasian individuals, thus suggesting that this SNP could be associated with DRC. However, the causal SNP and mechanism of DRC remain unclear. In the present study, dual luciferase assay results indicated that both SNPs are functional in lung cells. Through chromosome conformation capture, an enhancer containing the two functional SNPs was observed to bind the promoter of peroxisomal biogenesis factor 3 and phosphatase and actin regulator 2 antisense RNA 1 (PHACTR2AS1). Knockdown of PHACTR2AS1 could significantly influence lung cell proliferation, colony formation, migration and wound healing, which verified that PHACTR2AS1 is a novel oncogene for lung cancer. Through chromatin immunoprecipitation, the transcription factor POU class 2 homeobox 1 (POU2F1) was identified to bind to the surrounding segments of these two SNPs, and their interaction was investigated. The present study identified the mechanism via which rs9390123 and rs9399451 could influence DRC.
Assuntos
Reparo do DNA/genética , Lipoproteínas/genética , Neoplasias Pulmonares/genética , Proteínas de Membrana/genética , Proteínas dos Microfilamentos/genética , Proteínas do Tecido Nervoso/genética , Peroxinas/genética , Polimorfismo de Nucleotídeo Único/genética , RNA Antissenso/genética , Regulação Neoplásica da Expressão Gênica , Estudo de Associação Genômica Ampla , Humanos , Oncogenes/genéticaRESUMO
OBJECTIVE: To explore he curative effect and safety of Prednisone in combination with Mycophenolate in treating ITP and its influence on the level of peripheral blood T lymphocytes and NK lymphocytes. METHOD: 93 cases of ITP patients were divided into the observation group and the control group by the Random Number Table method, 48 cases for the observation group, 45 for another. Patients in the control group orally took 0.5â¯mg/kg Prednisone Acetate tablets daily, two times each in the morning and evening. And the observation group, based on the treatment of the control group, orally took Mycophenolate Mofetil Dispersible tablets twice a day, 1â¯g each time. According to patients' conditions, 3 to 5 courses were set for treatment with 3â¯weeks a course. Compared PLT amount and the changing situation of inflammatory factors, CD3+ and CD3+CD95L+ before and after the treatment, the level of CD3+Caspase-3+ and CD3+Caspase-8+, NK+, NK+ CD95L+, NK+Caspase-3+, NK+Caspase-8, the curative effect and adverse events. RESULT: After treatment, PLT amount in both groups increased, and the increase in the observation group was much higher than that of the control group, the difference had statistical significance (Pâ¯<â¯0.05). The time needed for PLT amount in the control group to reach the normal and peak values was longer than that of the observation group, whose PLT peak value was higher than another group. The difference had statistical significance (Pâ¯<â¯0.05). After the treatment, the levels of TNF-α and IL-6 were lowered, and the value of the observation group was lower than that of another. The difference between and within the group has statistical significance. After the treatment, the level of CD3+, CD3+CD95L+ and CD3+Caspase-8+ is much higher and CD3+Caspase-3+ level lower than that before the treatment. The difference has statistical significance (Pâ¯<â¯0.05). After the treatment, the level of NK+ and NK+ CD95L+ is higher and the level of NK+Caspase-8+ lower than that before the treatment. The difference has statistical significance (Pâ¯<â¯0.05). After the treatment, the total effective rate 91.67% of the observation group is much higher than that 75.56% of another. The difference has statistical significance (Pâ¯<â¯0.05). After the treatment, the incidence rate of adverse events in the control group is 11.11% (5/45), while 4.17% (2/48) in the observation group. The difference between groups has statistical significance (χ2â¯=â¯3.890, Pâ¯<â¯0.05). CONCLUSION: The curative effect of Prednisone in combination with Mycophenolate on ITP patients is better than orally taking Prednisone tablets. Moreover, when it comes to Prednisone in combination with Mycophenolate, both the PLT amount and immunocompetence are improved without much adverse reaction, and the molecules of peripheral blood T lymphocytes and NK lymphocytes can be effectively adjusted to relieve the symptoms. So the method is trustworthy to be popularized for clinical practices.
RESUMO
China has serious lead pollution and a high incidence of childhood rickets. High lead levels have been reported in childhood rickets, but the results were inconsistent.To evaluate the association between body lead levels and childhood rickets.After a systematic literature search, we identified 15 studies determining body lead levels between rickets children and healthy controls, and 4 studies focusing on the cases of different disease severity. Standard mean differences (SMD) and the corresponding 95% confidence intervals (CI) were pooled to compare the lead levels between different groups.Sixteen case-control studies were included with a total of 5082 cases and 6054 controls. Compared with healthy controls, the body lead levels in rickets children were significantly higher (SMD (95%CI): 0.67 (0.41-0.93)), and subgroup analyses showed consistent results. The cases with moderate-to-severe disease activity also had a significantly higher lead level than mild-to-moderate cases (SMD (95%CI): 0.64 (0.31-0.97)).This meta-analysis suggested an association between body lead levels and childhood rickets, and lead exposure might be a risk factor for rickets.
Assuntos
Exposição Ambiental/efeitos adversos , Chumbo/sangue , Raquitismo , Reabsorção Óssea/induzido quimicamente , Desenvolvimento Infantil/efeitos dos fármacos , Pré-Escolar , China/epidemiologia , Correlação de Dados , Humanos , Lactente , Estudos Observacionais como Assunto , Raquitismo/sangue , Raquitismo/diagnóstico , Raquitismo/epidemiologia , Fatores de Risco , Índice de Gravidade de DoençaRESUMO
In this work we have developed a unique structure of ultrathin (5nm) TiO2 nanolayers grafted graphene nanosheets (TiO2/G) and integrated oxygen vacancy (VO) into TiO2 to enhance its lithium storage and photocatalytic performances. The defective TiO2/G was synthesized by a solvothermal and subsequent thermal treatment method. When treated in a H2 atmosphere, the resulting TiO2-x/G(H2) has lower crystallinity, smaller crystal size, richer surface VO, higher surface area, larger pore volume, and lower charge transfer resistance than that reduced by NaBH4 solid, i.e., TiO2-x/G(NaBH4). More importantly, the surface VO in the TiO2-x/G(H2) could remarkably inhibit the recombination of photogenerated electron-hole pairs compared with the bulk Vo in the TiO2-x/G(NaBH4). As a result, the combination of all the factors contributed to the superiority of TiO2-x/G(H2), which demonstrated not only 70% higher specific capacity, longer cycling performance (1000 cycles) and better rate capability for lithium-ion battery, but also higher photocatalytic activity and 1.5 times faster degradation rate for organic pollutants removal than TiO2-x/G(NaBH4). The findings in this work will benefit the fundamental understanding of TiO2/G surface chemistry and advance the design and preparation of functional materials for energy storage and water treatment.