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1.
Langmuir ; 40(9): 4772-4778, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38381871

RESUMO

Self-assembled monolayers (SAMs) emerging as promising hole-selective layers (HSLs) are advantageous for facile processability, low cost, and minimal material consumption in the fabrication of both perovskite solar cells (PSCs) and organic solar cells (OSCs). However, owing to the different nature between perovskites and organic semiconductors, few SAMs were reported to effectively accommodate both PSCs and OSCs at the same time. In this regard, a universally applicable SAM that can accommodate both perovskites and organic semiconductors could be desirable for simplifying cell manufacturing, especially from an industrial perspective. In this work, we designed a SAM, TDPA-Cl by introducing chlorinated phenothiazine as the headgroup and linking with anchor phosphonic acid through a butyl chain. The resulting dense SAM was carefully characterized in terms of molecular bonding, surface morphology, and packing density, and its functions in OSCs and PSCs were discussed from the aspects of interactions with the absorber layer, energy level alignment, and charge-selective dipoles. The PM6:Y6-based OSCs with TDPA-Cl SAM as the HSL showed a superior performance to those with PEDOT:PSS. Furthermore, the universality was proved with an efficiency of 17.4% in the D18:Y6 system. In PSCs, the TDPA-Cl-based devices delivered a better performance of 22.4% than the PTAA-based devices (20.8%) with improved processability and reproducibility. This work represents a SAM with reasonably good compromise between the differing requirements of OSCs and PSCs.

2.
Sensors (Basel) ; 24(7)2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38610293

RESUMO

The implementation of a progressive rehabilitation training model to promote patients' motivation efforts can greatly restore damaged central nervous system function in patients. Patients' active engagement can be effectively stimulated by assist-as-needed (AAN) robot rehabilitation training. However, its application in robotic therapy has been hindered by a simple determination method of robot-assisted torque which focuses on the evaluation of only the affected limb's movement ability. Moreover, the expected effect of assistance depends on the designer and deviates from the patient's expectations, and its applicability to different patients is deficient. In this study, we propose a control method with personalized treatment features based on the idea of estimating and mapping the stiffness of the patient's healthy limb. This control method comprises an interactive control module in the task-oriented space based on the quantitative evaluation of motion needs and an inner-loop position control module for the pneumatic swing cylinder in the joint space. An upper-limb endpoint stiffness estimation model was constructed, and a parameter identification algorithm was designed. The upper limb endpoint stiffness which characterizes the patient's ability to complete training movements was obtained by collecting surface electromyographic (sEMG) signals and human-robot interaction forces during patient movement. Then, the motor needs of the affected limb when completing the same movement were quantified based on the performance of the healthy limb. A stiffness-mapping algorithm was designed to dynamically adjust the rehabilitation training trajectory and auxiliary force of the robot based on the actual movement ability of the affected limb, achieving AAN control. Experimental studies were conducted on a self-developed pneumatic upper limb rehabilitation robot, and the results showed that the proposed AAN control method could effectively estimate the patient's movement needs and achieve progressive rehabilitation training. This rehabilitation training robot that simulates the movement characteristics of the patient's healthy limb drives the affected limb, making the intensity of the rehabilitation training task more in line with the patient's pre-morbid limb-use habits and also beneficial for the consistency of bilateral limb movements.


Assuntos
Robótica , Humanos , Extremidade Superior , Movimento (Física) , Movimento , Algoritmos
3.
Molecules ; 29(3)2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38338333

RESUMO

Bacterial infections pose a significant risk to human health. Magnolol, derived from Magnolia officinalis, exhibits potent antibacterial properties. Synthetic biology offers a promising approach to manufacture such natural compounds. However, the plant-based biosynthesis of magnolol remains obscure, and the lack of identification of critical genes hampers its synthetic production. In this study, we have proposed a one-step conversion of magnolol from chavicol using laccase. After leveraging 20 transcriptomes from diverse parts of M. officinalis, transcripts were assembled, enriching genome annotation. Upon integrating this dataset with current genomic information, we could identify 30 laccase enzymes. From two potential gene clusters associated with magnolol production, highly expressed genes were subjected to functional analysis. In vitro experiments confirmed MoLAC14 as a pivotal enzyme in magnolol synthesis. Improvements in the thermal stability of MoLAC14 were achieved through selective mutations, where E345P, G377P, H347F, E346C, and E346F notably enhanced stability. By conducting alanine scanning, the essential residues in MoLAC14 were identified, and the L532A mutation further boosted magnolol production to an unprecedented level of 148.83 mg/L. Our findings not only elucidated the key enzymes for chavicol to magnolol conversion, but also laid the groundwork for synthetic biology-driven magnolol production, thereby providing valuable insights into M. officinalis biology and comparative plant science.


Assuntos
Compostos Alílicos , Lignanas , Magnolia , Fenóis , Humanos , Magnolia/genética , Magnolia/química , Lacase , Lignanas/química , Compostos de Bifenilo/química
4.
Phys Chem Chem Phys ; 25(36): 25055, 2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37671577

RESUMO

Correction for 'Lone pair driven anisotropy in antimony chalcogenide semiconductors' by Xinwei Wang et al., Phys. Chem. Chem. Phys., 2022, 24, 7195-7202, https://doi.org/10.1039/D1CP05373F.

5.
Opt Express ; 30(11): 19812-19823, 2022 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-36221748

RESUMO

We numerically investigate the transfer of optical information from a vector-vortex control beam to an unstructured probe beam, as mediated by an atomic vapour. The right and left circular components of these beams drive the atomic transitions of a double-V system, with the atoms acting as a spatially varying circular birefringent medium. Modeling the propagation of the light fields, we find that, for short distances, the vectorial light structure is transferred from the control field to the probe. However, for larger propagation lengths, diffraction causes the circular components of the probe field to spatially separate. We model this system for the D1 line of cold rubidium atoms and demonstrate that four wave mixing can lead to correlations between the optical polarization structure and the diffraction of light, generating coupled dynamics of the internal and external degrees of freedom.

6.
Phys Chem Chem Phys ; 24(12): 7195-7202, 2022 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-35262534

RESUMO

Antimony sulfide (Sb2S3) and selenide (Sb2Se3) have emerged as promising earth-abundant alternatives among thin-film photovoltaic compounds. A distinguishing feature of these materials is their anisotropic crystal structures, which are composed of quasi-one-dimensional (1D) [Sb4X6]n ribbons. The interaction between ribbons has been reported to be van der Waals (vdW) in nature and Sb2X3 are thus commonly classified in the literature as 1D semiconductors. However, based on first-principles calculations, here we show that inter-ribbon interactions are present in Sb2X3 beyond the vdW regime. The origin of the anisotropic structures is related to the stereochemical activity of the Sb 5s lone pair according to electronic structure analysis. The impacts of structural anisotropy on the electronic, dielectric and optical properties relevant to solar cells are further examined, including the presence of higher dimensional Fermi surfaces for charge carrier transport. Our study provides guidelines for optimising the performance of Sb2X3-based photovoltaics via device structuring based on the underlying crystal anisotropy.

7.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 44(5): 794-801, 2022 Oct.
Artigo em Zh | MEDLINE | ID: mdl-36325776

RESUMO

Objective To investigate the effect and mechanism of isorhapontigenin (ISO) in the protection of mice from the lipopolysaccharide (LPS)-induced acute lung injury (ALI). Methods RAW264.7 cells were cultured in vitro with different concentrations of ISO and the viability of the cells was measured by CCK-8 assay.Further,RAW264.7 cells were induced with 200 ng/ml LPS and then treated with ISO and the autophagy inhibitor 3-methyladenine (3-MA).Western blotting was employed to determine the expression of inflammatory cytokines [interleukin (IL)-1ß,IL-6,tumor necrosis factor-α (TNF-α),P65,phospho-P56 (p-P65),IκB,phospho-IκB (p-IκB),inducible nitric oxide synthase (iNOS),cyclooxygenase-2 (COX-2),and high mobility group box-1 (HMGB1)] and autophagy markers (LC3Ⅱ/Ⅰ,Beclin1,and P62).The reactive oxygen species (ROS) production of the cells was measured with the DCFH-DA probe.The mouse model of ALI was established by intraperitoneal injection of LPS (15 mg/kg).The pathological changes of the lung tissue were observed via HE staining.The expression of inflammatory cytokines and autophagy markers in the lung tissue was determined by Western blotting and the content of ROS in bronchoalveolar lavage fluid (BALF) by flow cytometry. Results ISO down-regulated the expression of IL-1ß,IL-6,TNF-α,iNOS,COX-2,and HMGB1 and inhibited the ROS production in the LPS-induced RAW264.7 cells (all P<0.05).Furthermore,it promoted the expression of LC3Ⅱ/Ⅰ and Beclin1 and inhibited the expression of P62,thereby activating autophagy (all P<0.05).However,the addition of 3-MA up-regulated the expression of p-P65/P65,p-IκB,iNOS,COX-2,and HMGB1,down-regulated that of IκB (all P<0.001),and promote the production of ROS.ISO mitigated the pathological changes in the lung tissue of ALI mice.It down-regulated the expression of p-P65/P65,p-IκB,iNOS,COX-2,and HMGB1 and up-regulated that of IκB in the lung tissue (all P<0.001) and decreased the ROS production in BALF.However,such protective effect was reversed by 3-MA. Conclusion ISO may induce autophagy of macrophages to protect mice from LPS-induced ALI.


Assuntos
Lesão Pulmonar Aguda , Proteína HMGB1 , Animais , Camundongos , Lesão Pulmonar Aguda/induzido quimicamente , Lesão Pulmonar Aguda/metabolismo , Lesão Pulmonar Aguda/patologia , Proteína Beclina-1/farmacologia , Ciclo-Oxigenase 2/metabolismo , Citocinas , Proteína HMGB1/metabolismo , Interleucina-6 , Lipopolissacarídeos , Pulmão/patologia , NF-kappa B/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fator de Necrose Tumoral alfa/metabolismo
8.
J Craniofac Surg ; 32(5): 1796-1799, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33587526

RESUMO

OBJECTIVE: To explore the preliminary application of three-dimensional (3D) printing technique in preoperative localization of meningiomas in primary hospitals. PATIENTS AND METHODS: The enrolled subjects were 13 patients in the Department of Neurosurgery, Affiliated Hospital of Binzhou Medical College, Shandong Province between December 2018 and June 2020, including CT or MRI data from eight cases of brain meningiomas and five cases of cerebrospinal meningiomas. The Mimics 17.0 software package was applied to reconstruct the 3D images and print out the 3D guide. The authors placed the 3D printed guide on the surgical area for preoperative tumor location. RESULTS: The 3D printed guides for all patients were successfully designed and printed out. Simpson grade I resection was performed on all tumors. No significant hematoma, brain edema, or neurological symptoms were observed in the postoperative patients, and the surgical results were good. CONCLUSIONS: The authors can use 3D printing technology for precise preoperative localization of meningiomas. Grassroots hospitals can also use this technique because of its economic, accurate, and personalized characteristics.


Assuntos
Neoplasias Meníngeas , Meningioma , Hospitais , Humanos , Imageamento Tridimensional , Neoplasias Meníngeas/diagnóstico por imagem , Neoplasias Meníngeas/cirurgia , Meningioma/diagnóstico por imagem , Meningioma/cirurgia , Impressão Tridimensional
9.
J Surg Res ; 245: 99-106, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31415935

RESUMO

BACKGROUND: Brainstem hemorrhage is an acute and severe neurosurgical disease. Cerebral hemorrhage is surgically treated via hematoma puncture drainage because of its minimally invasive nature. However, the placement of puncture must be extremely accurate due to the special anatomical location of the brainstem and its physiological functions. The present study aimed to evaluate whether the application of a three-dimensional (3D)-printed navigation mold achieved good outcomes in the surgical treatment of brainstem hemorrhage. MATERIAL AND METHODS: The present study included seven patients (three men and four women aged 40-56 y) who underwent 3D print-assisted hematoma puncture drainage between June 2016 and March 2018 at Binzhou Medical University Hospital. The amount of brainstem hemorrhage was 15-47 mL. We analyzed the basic surgical conditions, deviation distance, and postoperative clinical improvement. RESULTS: In all cases, the operation was completed successfully; no patient died or contracted an infection intraoperatively. The end of the puncture tube was located in the hematoma cavity in all cases. The deviation distance ranged from 2.5 to 7.2, and this distance gradually reduced with improvements in the technique. The hematoma drainage achieved satisfactory postoperative outcomes, with improvements in symptoms such as respiratory failure and hyperthermia. CONCLUSIONS: Use of a 3D-printed navigation mold for puncture drainage of brainstem hemorrhage realized the purpose of individualized and precision medicine, which is important in maintaining the vital signs of patients with severe brainstem hemorrhage.


Assuntos
Hemorragia Cerebral/cirurgia , Drenagem/instrumentação , Hematoma/cirurgia , Modelos Anatômicos , Impressão Tridimensional , Punções/instrumentação , Adulto , Tronco Encefálico/irrigação sanguínea , Tronco Encefálico/diagnóstico por imagem , Tronco Encefálico/cirurgia , Hemorragia Cerebral/complicações , Hemorragia Cerebral/diagnóstico , Drenagem/métodos , Feminino , Hematoma/diagnóstico , Hematoma/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Punções/métodos , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X , Resultado do Tratamento
10.
J Am Chem Soc ; 141(19): 7670-7674, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31058498

RESUMO

Chemical vapor deposition (CVD) enables the large-scale growth of high-quality graphene film and exhibits considerable potential for the industrial production of graphene. However, CVD-grown graphene film contains surface contamination, which in turn hinders its potential applications, for example, in electrical and optoelectronic devices and in graphene-membrane-based applications. To solve this issue, we demonstrated a modified gas-phase reaction to achieve the large-scale growth of contamination-free graphene film, i.e., superclean graphene, using a metal-containing molecule, copper(II) acetate, Cu(OAc)2, as the carbon source. During high-temperature CVD, the Cu-containing carbon source significantly increased the Cu content in the gas phase, which in turn suppressed the formation of contamination on the graphene surface by ensuring sufficient decomposition of the carbon feedstock. The as-received graphene with a surface cleanness of about 99% showed enhanced optical and electrical properties. This study opens a new avenue for improving graphene quality with respect to surface cleanness and provides new insight into the mechanism of graphene growth through the gas-phase reaction pathway.

11.
Appl Environ Microbiol ; 85(18)2019 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-31300399

RESUMO

Contamination by fungi may pose a threat to the long-term operation of the International Space Station because fungi produce organic acids that corrode equipment and mycotoxins that harm human health. Microgravity is an unavoidable and special condition in the space station. However, the influence of microgravity on fungal metabolism has not been well studied. Clinostat rotation is widely used to simulate the microgravity condition in studies carried out on Earth. Here, we used metabolomics differential analysis to study the influence of clinostat rotation on the accumulation of organic acids and related biosynthetic pathways in ochratoxin A (OTA)-producing Aspergillus carbonarius As a result, clinostat rotation did not affect fungal cell growth or colony appearance but significantly increased the accumulation of organic acids, particularly isocitric acid, citric acid, and oxalic acid, and OTA both inside cells and in the medium, as well as resulted in a much higher level of accumulation of some products inside than outside cells, indicating that the transport of these metabolites from the cell to the medium was inhibited. This finding corresponded to the change in the fatty acid composition of cell membranes and the reduced thickness of the cell walls and cell membranes. Amino acid and energy metabolic pathways, particularly the tricarboxylic acid cycle, were influenced the most during clinostat rotation compared to the effects of normal gravity on these pathways.IMPORTANCE Fungi are ubiquitous in nature and have the ability to corrode various materials by producing metabolites. Research on how the space station environment, especially microgravity, affects fungal metabolism is helpful to understand the role of fungi in the space station. This work provides insights into the mechanisms involved in the metabolism of the corrosive fungus Aspergillus carbonarius under simulated microgravity conditions. Our findings have significance not only for preventing material corrosion but also for ensuring food safety, especially in the space environment.


Assuntos
Ácidos/metabolismo , Aspergillus/metabolismo , Ausência de Peso , Vias Biossintéticas , Metabolômica , Ocratoxinas/metabolismo
12.
Appl Microbiol Biotechnol ; 103(20): 8609-8618, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31522284

RESUMO

Colorimetric, fluorescence, and paper-based method were developed to measure the Hg2+ level in water using iturin A, a lipopeptide produced by Bacillus subtilis. Firstly, iturin was used to synthesize highly stable and uniformly sized silver nanoparticles (AgNPs). Secondly, the iturin-AgNPs were found to be highly selective and sensitive to Hg2+. The absorbance of the reaction system showed a good linear correlation with the Hg2+ concentration from 0.5 to 5 mg/L at 450 nm in the UV-Vis spectroscopy detection with the limit of detection (LOD) of 0.5 mg/L. When the reaction system was detected by fluorescence measurement, a good linear relationship was found between the fluorescence intensity and Hg2+ concentration from 0.05 to 0.5 mg/ at 415 nm with the LOD of 0.05 mg/L. Lastly, a paper-based detection method was developed. The developed method was successfully used to detect Hg2+ in contaminated polluted waters and showed acceptable results in terms of sensitivity, selectivity and stability. The paper-based method could distinguish Hg2+ at levels higher than 0.05 mg/L, thereby meeting the guidelines of the effluent quality standard for industries (0.05 mg/L). In summary, this method can be used daily by various industries to monitor the Hg2+ level in effluent water.


Assuntos
Técnicas de Química Analítica/métodos , Colorimetria/métodos , Fluorometria/métodos , Mercúrio/análise , Peptídeos Cíclicos/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/análise , Bacillus subtilis/enzimologia , Nanopartículas Metálicas , Papel , Sensibilidade e Especificidade
13.
Acta Biochim Biophys Sin (Shanghai) ; 51(8): 767-777, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31236585

RESUMO

Ischemic stroke has become one of the leading causes of deaths and disabilities all over the world. In this study, we investigated the therapeutic effects of combined bone marrow stromal cells (BMSCs) and oxiracetam treatments on acute cerebral ischemia/reperfusion (I/R) injury. A rat model of middle cerebral artery occlusion (MCAO) followed by complete reperfusion, as well as a cortex neuron oxygen-glucose deprivation (OGD) model was established. When compared with BMSCs or oxiracetam monotherapy, combination therapy significantly improved functional restoration with decreased infarct volume in observed ischemic brain. We propose that it may occur through the transient receptor potential canonical (TRPC)6 neuron survival pathway. The increased expression of TRPC6 along with the reduction of neuronal cell death in the OGD cortex neurons and combination therapy group indicated that the TRPC6 neuron survival pathway plays an important role in the combined BMSCs and oxiracetam treatments. We further tested the activity of the calpain proteolytic system, and the results suggested that oxiracetam could protect the integrity of TRPC6 neuron survival pathway by inhibiting TRPC6 degradation. The protein levels of phospho-cAMP response element binding protein (p-CREB) were tested. It was found that BMSCs play a role in the activation of the TRPC6 pathway. Our study suggests that the TRPC6 neuron survival pathway plays a significant role in the protective effect of combined BMSCs and oxiracetam treatments on acute cerebral I/R injury. Combined therapy could inhibit the abnormal degradation of TRPC6 via decreasing the activity of calpain and increasing the activation of TRPC6 neuron survival pathway.


Assuntos
Isquemia Encefálica/terapia , Células-Tronco Mesenquimais/citologia , Pirrolidinas/administração & dosagem , Traumatismo por Reperfusão/terapia , Canais de Cátion TRPC/fisiologia , Animais , Transplante de Medula Óssea , Calpaína/metabolismo , Córtex Cerebral/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Glucose , Infarto da Artéria Cerebral Média/terapia , Masculino , Neurônios/patologia , Fármacos Neuroprotetores/uso terapêutico , Oxigênio , Ratos , Ratos Wistar , Acidente Vascular Cerebral/terapia , Resultado do Tratamento
14.
Anim Biotechnol ; 30(3): 212-218, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29936889

RESUMO

Litter size is an important economic traits in pigs. SLA-11 gene is a member of SLA (swine leukocyte antigen) complex. In our previous study, the SLA-11 gene was differentially expressed in PMSG-hCG stimulated preovulatory ovarian follicles of Chinese Taihu and Large White sows. Here, we identified two mutations (c.754-132 T > C and c.1421 + 38 T > C) in SLA-11 gene and analyzed the associations of two SNPs with litter size traits in Large White (n = 263) and DIV (n = 117) sows. The results showed that in Large White pigs, SLA-11 c.754-132 CC sows produced 0.74 and 0.87 more pigs per litter for TNB and NBA of all parities than did TT sows (p < .05); In DIV pigs, SLA-11 c.754-132 CC sows produced 1.17 more pigs per litter for TNB of all parities than did TC sows (p < .05). In Large White pigs, SLA-11 c.1421 + 38 CC sows produced 0.9 more pigs per litter for TNB of all parities than did TT sows (p < .05), while in DIV pigs SLA-11 c.1421 + 38 CC sows produced 0.84 and 0.7 less pigs per litter for TNB and NBA of all parities than did TT sows (p < .05). Our research indicated that SLA-11 mutations were potential molecular markers for improving the litter size traits in pigs.


Assuntos
Antígenos de Histocompatibilidade Classe I/genética , Polimorfismo de Nucleotídeo Único/genética , Reprodução , Suínos/genética , Animais , Gonadotropina Coriônica/farmacologia , Combinação de Medicamentos , Feminino , Gonadotropinas Equinas/farmacologia , Tamanho da Ninhada de Vivíparos/genética , Mutação , Folículo Ovariano/efeitos dos fármacos , Gravidez , Suínos/fisiologia
15.
Anim Biotechnol ; 30(4): 287-292, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30178695

RESUMO

To select new Large White line with high number of piglets born, genotypes of estrogen receptor (ESR), the follicle stimulating hormone ß subunit (FSHß), catenin alpha like 1 (CTNNAL1) and miR-27a were tested in 472 Large White sows. The associations of different genotypes with litter size traits were also studied. The results showed ESRBB and FSHßBB sows produced 0.41-1.49 more pigs per litter (p < .05) for total number born (TNB) and number born alive (NBA) than did other corresponding genotypes. TNB of CTNNAL1CG sows is 0.50 more pigs per litter (p < .05) than that of CTNNAL1GG sows with the dominance effect of 0.25 pigs per litter (p < .05). miR-27aBB sows had a less estimated breeding value (EBV) to TNB and had a more number of mummified pigs (NM) than did miR-27aAA or miR-27aAB sows (p < .05). Therefore, ESRB, FSHßB, CTNNAL1G, miR-27aA allele was favorable for litter size traits. Furthermore, combined genetic effect analysis showed ESRAAFSHßBB, ESRAACTNNAL1CG, ESRAAmiR-27aAA, FSHßBBCTNNAL1CC, FSHßBBmiR-27aAA and CTNNAL1CG miR-27aAB was the favorable combined genotype for litter size traits. These results identified favorable alleles and genotypes for litter size traits and suggested a potential selection scheme for litter size in Large White pigs.


Assuntos
Subunidade beta do Hormônio Folículoestimulante/genética , Tamanho da Ninhada de Vivíparos/genética , MicroRNAs/genética , Receptores de Estrogênio/genética , Suínos/genética , alfa Catenina/genética , Alelos , Animais , Cruzamento , Feminino , Marcadores Genéticos , Genótipo , Polimorfismo de Nucleotídeo Único , Gravidez
16.
Angew Chem Int Ed Engl ; 58(41): 14446-14451, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31286615

RESUMO

Contamination commonly observed on the graphene surface is detrimental to its excellent properties and strongly hinders its application. It is still a great challenge to produce large-area clean graphene film in a low-cost manner. Herein, we demonstrate a facile and scalable chemical vapor deposition approach to synthesize meter-sized samples of superclean graphene with an average cleanness of 99 %, relying on the weak oxidizing ability of CO2 to etch away the intrinsic contamination, i.e., amorphous carbon. Remarkably, the elimination of amorphous carbon enables a significant reduction of polymer residues in the transfer of graphene films and the fabrication of graphene-based devices and promises strongly enhanced electrical and optical properties of graphene. The facile synthesis of large-area superclean graphene would open the pathway for both fundamental research and industrial applications of graphene, where a clean surface is highly needed.

17.
Nano Lett ; 17(12): 7539-7543, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29164881

RESUMO

Strain serves as a powerful freedom to effectively, reversibly, and continuously engineer the physical and chemical properties of two-dimensional (2D) materials, such as bandgap, phase diagram, and reaction activity. Although there is a high demand for full characterization of the strain vector at local points, it is still very challenging to measure the local strain amplitude and its direction. Here, we report a novel approach to monitor the local strain vector in 2D molybdenum diselenide (MoSe2) by polarization-dependent optical second-harmonic generation (SHG). The strain amplitude can be evaluated from the SHG intensity in a sensitive way (-49% relative change per 1% strain); while the strain direction can be directly indicated by the evolution of polarization-dependent SHG pattern. In addition, we employ this technique to investigate the interlayer locking effect in 2H MoSe2 bilayers when the bottom layer is under stretching but the top layer is free. Our observation, combined with ab initio calculations, demonstrates that the noncovalent interlayer interaction in 2H MoSe2 bilayers is strong enough to transfer the strain of at least 1.4% between the bottom and top layers to prevent interlayer sliding. Our results establish that SHG is an effective approach for in situ, sensitive, and noninvasive measurement of local strain vector in noncentrosymmetric 2D materials.

18.
Phys Chem Chem Phys ; 19(35): 23942-23950, 2017 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-28808705

RESUMO

We have theoretically investigated the intrinsic carrier mobility in semimetals with tilted Dirac cones under both longitudinal and transverse acoustic phonon scattering. An analytical formula for the carrier mobility was obtained. It shows that tilting significantly reduces the mobility. The theory was then applied to 8B-Pmmn borophene and borophane (fully hydrogenated borophene), both of which have tilted Dirac cones. The predicted carrier mobilities in 8B-Pmmn borophene at room temperature are 14.8 × 105 and 28.4 × 105 cm2 V-1 s-1 along the x and y directions, respectively, both of which are higher than that in graphene. For borophane, despite its superhigh Fermi velocity, the carrier mobility is lower than that in 8B-Pmmn owing to its smaller elastic constant under shear strain.

19.
J Chem Phys ; 141(14): 144107, 2014 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-25318715

RESUMO

An analytic formula for the intrinsic carrier mobility of Dirac cones under acoustic phonon scattering conditions was obtained for 2D systems such as graphene and graphyne. The influences of both the transverse acoustic (TA) and longitudinal acoustic phonon modes and that of the anisotropy were considered. Some extraordinary characteristics unlike those predicted by the deformation potential theory were revealed: the mobility at the neutrality point is proportional to 1/T(3), where T is the temperature; also, carrier scattering by the TA phonons dominates the mobility of graphene, which explains the overestimation of the measured deformation potential of graphene in previous experiments. The theory was combined with first-principles calculations to determine the mobility of graphene and five graphynes with Dirac cones. It was predicted that most graphynes will have much higher mobility than graphene because of the suppression of the scattering by the TA phonons.

20.
Waste Manag ; 174: 328-339, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38091657

RESUMO

Co-gasification is crucial for large-scale clean conversion of coal and sludge. In this study, the effects of municipal sewage sludge (MSS, Fe2O3:48.11 %) and pharmaceutical sewage sludge (PSS, Fe2O3: 67.80 %) on ash fusion temperature (AFT) of high AFT Xiangyuan coal (XY) were explored using an AFT analysis, X-ray fluorescence spectrometry, X-ray diffraction, scanning electronic microscopy, and thermodynamics FactSage calculation. The results showed that when MSS or PSS ash mass ratios reached 20 % or 16 % (for XY mixtures, the mass ratio of MSS or PSS should be >5.81 wt% or 5.07 wt%), respectively, the AFT met the requirement of liquid-slag discharge for entrained-flow bed gasification. Under a reducing atmosphere (6:4, CO/CO2, volume ratio), Fe2+ destroyed the bridging-oxygen bonds in the network structure and generated low melting-point (MP) hercynite (FeAl2O4). This resulted in the AFT decreases in the XY mixtures with the additions of PSS or MSS. Meanwhile, the high calcium content (CaO: 13.40 %) easily reacted with Al2O3 and SiO2 and formed anorthite (CaAl2SiO8), which inhibited high-MP mullite formation and decreased the mixed XY AFT. With the increasing SS mass ratio, the surface of the ash sample and thermodynamic FactSage calculation were in good agreement with the experimental results.


Assuntos
Carvão Mineral , Ferro , Esgotos/química , Cinza de Carvão , Temperatura , Dióxido de Silício
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