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1.
Nanotechnology ; 2020 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-32375129

RESUMO

N-doped carbon-based materials are crucial electrically conductive additives and non-metal electrocatalysts for oxygen reduction reaction. At present, many researches are focused on the effects of micropore, mesopore and hierarchical pore structure on the catalytic activity, however, there are few works concerning the role of large-dimension through-hole structure. Hence, in this work, we prepare two kinds of carbon materials with large through-hole structure, i.e. N-doped carbon hollow-spheres and hollow-tubes, as the oxygen reduction catalysts. The synthesis follows template-free morphology-controlled pyrolysis, which is more convenient than the preparation of conventional N-doped nanotubes and graphene. The resultant N-doped carbon hollow-spheres and hollow-tubes exhibit evidently enhanced ORR catalytic activity, remarkable long-term stability and methanol resistance. The large-dimension through-hole structure is found to account for the increase in mass transfer.

2.
Spectrochim Acta A Mol Biomol Spectrosc ; 236: 118347, 2020 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-32305837

RESUMO

As is known, Zn2+ plays a vital role in a variety of biological processes but excessive exposure of Zn2+ to human beings can cause toxicity, inducing a series of overt poisoning symptoms and neurodegenerative disorders. Thus, we designed and synthesized two quinoline-derived Schiff-bases HL1 and HL2, and investigated the fluorescence emission responses of these two Schiff-bases to various metal ions. A significant enhancement in fluorescence emission band centered at 450 nm was observed in the ethanolic solution of HL1 with addition of Zn2+, while remarkably lower fluorescence emission enhancement was obtained in the case of HL2 in which one methyl group was introduced to the azomethine carbon. In addition, HL1 showed good selectivity and high sensitivity towards Zn2+ in the existence of other various interfering metal ions, and the reversibility and regeneration of HL1 were also perfect for extending its applications in environmental and biological systems. Therefore, HL1 could be identified as a fluorescent probe for sensing Zn2+ environmentally and biologically.

3.
Neuroreport ; 31(2): 99-108, 2020 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-31895751

RESUMO

Neuroinflammation is a common pathogenic mechanism in several neurodegenerative diseases, and glial cells are the primary inflammatory mediators of the central nervous system (CNS). Acute neuronal injury, infection, and chronic neurodegeneration may induce astrocyte activation, which is a response characterized by hyperproliferation and release of multiple inflammatory signaling factors. The opioid analgesic oxycodone has demonstrated anti-inflammatory efficacy in peripheral tissue, but its effects on the CNS have not been studied. We evaluated the inhibitory effects of oxycodone on astrocyte activation and proinflammatory mediator production in response to lipopolysaccharide (LPS). Our results showed that oxycodone (5-20 µg/ml) dose-dependently inhibited the LPS-induced astrocytosis, as measured by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide and bromodeoxyuridine assays, as well as the overexpression of glial fibrillary acidic protein, which are two hallmarks of reactive astrogliosis in neurodegenerative diseases. Oxycodone also decreased both the mRNA and protein expression levels of proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1ß. Besides, oxycodone increased the expression of the nuclear factor kappa-B (NF-κB) endogenous inhibitor IκB-α, and blocked NF-κB translocation to the nucleus. The anti-inflammatory efficacy of oxycodone on rat astrocytes increased with pretreatment duration. These results suggest that oxycodone can suppress neuroinflammation by inhibiting NF-κB signaling in astrocytes. Targeting the astrocytic NF-κB-mediated inflammatory response may be an effective therapeutic strategy against diseases involving neuroinflammatory damage.

4.
Huan Jing Ke Xue ; 40(11): 4971-4979, 2019 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854563

RESUMO

Nanoparticles (NPs) have increasingly been applied in consumer and industrial products because of their magnetic, optical, electronic, sensitive, antibacterial, disinfection, and UV shielding properties. The wide production and application of NPs has inevitably resulted in their release into the ecosystem through various channels and accumulation in organisms. NPs have a small particle size (1-100 nm), which is closely correlated with biotoxicity. To investigate the size-dependent effects of zinc oxide nanoparticles (ZnO NPs) on microbial community structure and diversity, as well as the nitrogen removal performance of a biological treatment system, laboratory scale horizontal subsurface flow constructed wetlands were operated for 28 days under the conditions of COD 200.0 mg·L-1, NH4+-N 12.5 mg·L-1, and total dissolved phosphorus 4.0 mg·L-1. The relationship between microbial community structure and its performance were discussed. The results indicated that three sized ZnO NPs (15, 50, and 90 nm) had no significant effect on COD removal at the concentration of 10 mg·L-1 but showed obvious particle size effects on nitrogen removal. High throughput sequencing indicated that the abundance of nitrifying bacteria in constructed wetland system was significantly lower than that of denitrifying bacteria, suggesting that the nitrification process was the key factor restricting the denitrification performance of wetlands. After exposure to ZnO NPs, the structure of microbial communities in constructed wetlands changed, and 15 nm ZnO NPs had a stronger inhibitory effect on nitrifying bacteria than those of 50 nm and 90 nm ZnO NPs.


Assuntos
Microbiota , Nanopartículas , Óxido de Zinco , Desnitrificação , Nitrogênio , Eliminação de Resíduos Líquidos , Áreas Alagadas
5.
Chin J Integr Med ; 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31776962

RESUMO

OBJECTIVE: To assess the efficacy and safety of Chinese medicine injection (CMI) for treating acute lung injury/acute respiratory distress syndrome (ALI/ARDS). METHODS: Randomized controlled trials (RCTs) were identified by searching 3 English databases and 4 Chinese databases from their inceptions until February 2019. The Cochrane Handbook was used to evaluate risk of bias in the included studies. Data analysis was conducted using RevMan 5.3.3 software. RESULTS: A total of 19 eligible RCTs involving 1,334 participants was included in this systematic review and meta-analysis. The main meta-analysis showed that CMI combined with conventional therapy (CT) was more effective than CT alone in reducing the acute physiology and chronic health evaluation (APACHE) H score [mean difference (MD): -1.74 points, 95% confidence interval (CI): -2.77 to -0.71, I2=0] and increasing the total effective rate [relative risk (RR): 1.35, 95% CI: 1.17 to 1.56, I2=37%]. Compared with CT, CMI combined with CT showed improvements in the arterial partial pressure of oxygen (PaO2, MD: 9.25 mm Hg, 95% CI: 0.87 to 17.63, I2=98%) and oxygenation index [arterial partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2), MD: 50.75 mm Hg, 95% CI: 35.18 to 66.31, I2=94%]. CMI plus CT was superior to CT in reducing the systemic inflammatory response syndrome (SIRS) score (MD: -0.84 points, 95% CI: -1.26 to -0.42, I2=65%), length of hospital stay (MD: -4.22 days, 95% CI: -6.49 to -1.95, I2=92%), and duration of mechanical ventilation (MD: -2.94 days, 95% CI: -4.68 to -1.21, I2=89%). Only 1 study reported adverse events. CONCLUSIONS: CMI as an adjuvant therapy showed great potential benefits for the treatment of ALI/ARDS. However, we could not make a definite conclusion due to low quality of included studies and uncertain security. Future studies should focus on improving research design, especially in blindness and placebo. The reporting of adverse events was also needed.

6.
BMC Plant Biol ; 19(1): 469, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31690290

RESUMO

BACKGROUND: Soybean (Glycine max (L.)) is one the most important oil-yielding cash crops. However, the soybean production has been seriously restricted by salinization. It is therefore crucial to identify salt tolerance-related genes and reveal molecular mechanisms underlying salt tolerance in soybean crops. A better understanding of how plants resist salt stress provides insights in improving existing soybean varieties as well as cultivating novel salt tolerant varieties. In this study, the biological function of GmNHX1, a NHX-like gene, and the molecular basis underlying GmNHX1-mediated salt stress resistance have been revealed. RESULTS: We found that the transcription level of GmNHX1 was up-regulated under salt stress condition in soybean, reaching its peak at 24 h after salt treatment. By employing the virus-induced gene silencing technique (VIGS), we also found that soybean plants became more susceptible to salt stress after silencing GmNHX1 than wild-type and more silenced plants wilted than wild-type under salt treatment. Furthermore, Arabidopsis thaliana expressing GmNHX1 grew taller and generated more rosette leaves under salt stress condition compared to wild-type. Exogenous expression of GmNHX1 resulted in an increase of Na+ transportation to leaves along with a reduction of Na+ absorption in roots, and the consequent maintenance of a high K+/Na+ ratio under salt stress condition. GmNHX1-GFP-transformed onion bulb endothelium cells showed fluorescent pattern in which GFP fluorescence signals enriched in vacuolar membranes. Using the non-invasive micro-test technique (NMT), we found that the Na+ efflux rate of both wild-type and transformed plants after salt treatment were significantly higher than that of before salt treatment. Additionally, the Na+ efflux rate of transformed plants after salt treatment were significantly higher than that of wild-type. Meanwhile, the transcription levels of three osmotic stress-related genes, SKOR, SOS1 and AKT1 were all up-regulated in GmNHX1-expressing plants under salt stress condition. CONCLUSION: Vacuolar membrane-localized GmNHX1 enhances plant salt tolerance through maintaining a high K+/Na+ ratio along with inducing the expression of SKOR, SOS1 and AKT1. Our findings provide molecular insights on the roles of GmNHX1 and similar sodium/hydrogen exchangers in regulating salt tolerance.


Assuntos
Proteínas de Plantas/metabolismo , Tolerância ao Sal/genética , Plantas Tolerantes a Sal/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Soja/metabolismo , Arabidopsis/genética , Inativação Gênica , Proteínas de Plantas/genética , Potássio/metabolismo , Plantas Tolerantes a Sal/genética , Sódio/metabolismo , Trocadores de Sódio-Hidrogênio/genética , Soja/genética , Estresse Fisiológico/genética , Regulação para Cima , Vacúolos/metabolismo
7.
Plant Physiol ; 181(4): 1519-1534, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31551360

RESUMO

Glyphosate, the most commonly used herbicide in the world, controls a wide range of plant species, mainly because plants have little capacity to metabolize (detoxify) glyphosate. Massive glyphosate use has led to world-wide evolution of glyphosate-resistant (GR) weed species, including the economically damaging grass weed Echinochloa colona An Australian population of E colona has evolved resistance to glyphosate with unknown mechanisms that do not involve the glyphosate target enzyme 5-enolpyruvylshikimate-3-P synthase. GR and glyphosate-susceptible (S) lines were isolated from this population and used for resistance gene discovery. RNA sequencing analysis and phenotype/genotype validation experiments revealed that one aldo-keto reductase (AKR) contig had higher expression and higher resultant AKR activity in GR than S plants. Two full-length AKR (EcAKR4-1 and EcAKR4-2) complementary DNA transcripts were cloned with identical sequences between the GR and S plants but were upregulated in the GR plants. Rice (Oryza sativa) calli and seedlings overexpressing EcAKR4-1 and displaying increased AKR activity were resistant to glyphosate. EcAKR4-1 expressed in Escherichia coli can metabolize glyphosate to produce aminomethylphosphonic acid and glyoxylate. Consistent with these results, GR E colona plants exhibited enhanced capacity for detoxifying glyphosate into aminomethylphosphonic acid and glyoxylate. Structural modeling predicted that glyphosate binds to EcAKR4-1 for oxidation, and metabolomics analysis of EcAKR4-1 transgenic rice seedlings revealed possible redox pathways involved in glyphosate metabolism. Our study provides direct experimental evidence of the evolution of a plant AKR that metabolizes glyphosate and thereby confers glyphosate resistance.

8.
ACS Appl Mater Interfaces ; 11(34): 31346-31355, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31381290

RESUMO

The present work is focused on developing external stress-free two-way triple shape memory polymers (SMPs). Accordingly, a series of innovative approaches are proposed for the material design and preparation. Polyurethane prepolymers carrying crystalline polytetrahydrofuran (PTMEG) and poly(ε-caprolactone) (PCL) as the switching phases are respectively synthesized in advance and then cross-linked to produce the target material. The stepwise method is believed to be conducive to manipulation of the relative contribution of PCL and PTMEG. Moreover, the chain extender, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol (UPy), is incorporated to establish hydrogen bonds among the macromolecules. By straightforward stretching treatment at different temperatures, the hydrogen bond networks are successfully converted into an internal stress provider, which overcomes the challenge of stress relaxation of the melted low melting temperature polymer (i.e., PTMEG) and increases the efficiency of stress transfer. Meanwhile, the contraction force of the switching phases is tuned to match the internal tensile stress. As a result, the internal stress provider can closely collaborate with melting/recrystallization of the crystalline domains, leading to the repeated multiple shape memory effects. The cross-linked polyurethane is thus able to reversibly morph among three shapes and displays its potentials as soft robot and actuator. The strategy reported here has the advantages of easily accessible raw materials, simple reaction, and facile programing/deprograming/reprograming, so that it possesses wide applicability.

9.
Ying Yong Sheng Tai Xue Bao ; 30(7): 2481-2489, 2019 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-31418251

RESUMO

Wetland plays an important role in stabilizing climate change and makes a significant contribution to global soil carbon storage due to its huge carbon storage capacity. Based on a summary of estimation methods of carbon storage, this study analyzed carbon storage and its influencing factors of typical wetlands in China, inclusing climate, vegetation, soil property and land use. The results showed that wetlands in Northeast China and the Tibetan Plateau had the highest carbon sto-rage among the eight wetland areas. Peat wetland had the highest carbon storage in inland area due to its higher stability, lower decomposition rate, and the impact of phenol oxidase. The bidirectional interference of single factor and combined effects of multiple factors made the influencing factors and mechanisms more complicated. Our results would contribute to the prediction and evaluation of wetland carbon storage and the value of ecosystem services through laying emphasis on the combined effects of multiple factors and applying the data assimilation technology.


Assuntos
Sequestro de Carbono , Carbono , Áreas Alagadas , China , Ecossistema , Solo
10.
Polymers (Basel) ; 11(6)2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31159423

RESUMO

Polymer foams have low density, good heat insulation, good sound insulation effects, high specific strength, and high corrosion resistance, and are widely used in civil and industrial applications. In this paper, the classification of polymer foams, principles of the foaming process, types of blowing agents, and raw materials of polymer foams are reviewed. The research progress of various foaming methods and the current problems and possible solutions are discussed in detail.

11.
Materials (Basel) ; 12(8)2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30991737

RESUMO

In this paper, a wireless oxygen sensor based on a surface acoustic wave (SAW) was reported. For high-temperature applications, novel Al2O3/ZnO/Pt multilayered conductive film was deposited on langasite substrate as the electrodes, and ZnO film obtained by the pulse laser deposition (PLD) method was used as the sensitive film. The measurements of X-ray diffraction (XRD) and a scanning electron microscope (SEM) showed that the c-axis orientation of the ZnO grains and the surface morphology of the films were regulated by the deposition temperature. Meanwhile, the gas response of the sensor was strongly dependent on the surface morphology of the ZnO film. The experimental results showed that the oxygen gas sensor could operate at a high-temperature environment up to 850 °C with good stability for a long period. The max frequency shift of the sensors reaches 310 kHz, when exposed to 40% O2 gas at 850 °C. The calculated standard error of the sensors in a high-temperature measurement process is within 3%. Additionally, no significant signal degradation could be observed in the long-term experimental period. The prepared SAW oxygen gas sensor has potential applications in high-temperature sensing systems.

12.
Spectrochim Acta A Mol Biomol Spectrosc ; 218: 342-347, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31026711

RESUMO

Upon excitation of the visible light, probes show colorimetric and fluorescent responses to the specific metal ion, which can be easily detected by the naked eye. Owing to the excitation of the visible light at 423 nm, a novel and simple Schiff-base receptor based chromone derivative called 7-methoxychromone-3-carbaldehyde-(indole-3-formyl) hydrazone (MCIH2) had been investigated as a selective and sensitive probe for Al3+ with colorimetric and fluorescent responses. Upon addition of Al3+ to compound MCIH2 solution, compound MCIH2 could respond to Al3+ with a good selective colorimetric signal, which was easily observed from colorless to yellow-green by the naked eye. Furthermore, a remarkable fluorescence emission enhancement with an "OFF-ON" signal by over 700-fold was triggered, but other various metal ions had no such significant effects on the fluorescence emission. In addition, the detection limit of compound MCIH2 for recognizing Al3+ was evaluated to be as low as 1 × 10-7 M level, which was sufficiently low for sensing Al3+ widely distributed in various environmental and biological systems.

13.
Ying Yong Sheng Tai Xue Bao ; 30(2): 563-572, 2019 Feb 20.
Artigo em Chinês | MEDLINE | ID: mdl-30915809

RESUMO

Litter of Suaeda glauca, Phragmites australis, and Spartina alterniflora from coastal wetland of Jiaozhou Bay was decomposed in a laboratory experiment. The contents of soil labile organic carbon including dissolved organic carbon (DOC) and microbial biomass carbon (MBC) were determined, with the spectra characteristics of which being investigated by three-dimensional fluorescence spectroscopy. The results showed that the contents of soil labile organic carbon during litter decomposition increased first, then decreased, and finally tended to be stable. Different litter types and adding ways had different effects on soil labile organic carbon. The contents of soil DOC and MBC decreased in the order of Suaeda glauca, Spartina alterniflora and Phragmites australis. Soil mixed with bulk leaf litter had more soil labile organic carbon than surface mulch. The number and position of fluorescence peak, and fluorescence intensity changed during litter decomposition. No tyrosine-like peaks appeared in the soil with litter addition. Many factors drove litter decomposition, with microbial decomposition being the dominant factor and litter nature as the essential factor. Litter decomposition could improve the content of soil active organic carbon and enhance the stability of soil carbon pool. Litter decomposition changed the structure and chemical composition of soil DOC, which improved its ability of migration and transformation in soil. Moreover, this process enhanced its biodegradability and microbial bioavailability, promoted the production of endogenous DOC by microorganisms, and consequently stimulated carbon cycling of wetland soil.


Assuntos
Solo , Áreas Alagadas , Baías , Carbono , China , Espectrometria de Fluorescência
14.
Ying Yong Sheng Tai Xue Bao ; 30(3): 1025-1034, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30912396

RESUMO

Constructed wetlands (CWs) performs excellently in removing pollutants from agricultural runoff, and thus have been widely used as an effective measure to control agricultural runoff pollution. Based on reviews on domestic and overseas literature, we introduced the current situation of water bodies polluted by pesticides. The removal mechanisms of pesticides by CWs were elucidated according to physical, chemical and biological processes, and the main processes were discussed in detail. The removal efficiency of pesticides in CWs vary greatly with pesticide types. Based on their uses, the average removal efficiency of pesticides are in the order of insecticides > fungicides > herbicides. According to their chemical constitution, they follow the order of pyrethroid > organopho-sphorus > triazole > amide > triazine > ureas. Considering comprehensively, subsurface flow CWs perform better than surface flow CWs in removing pesticides. Furthermore, the effects of the physicochemical properties of pesticides, the types and operating parameters of CWs, pesticides concentration in influent, as well as vegetation on the removal of pesticides in CWs were also analyzed. Finally, problems in the current research and the future application of CWs in treating pesticides were discussed.


Assuntos
Áreas Alagadas , Agricultura , Herbicidas , Praguicidas , Poluentes Químicos da Água
15.
Sci Rep ; 9(1): 92, 2019 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-30643178

RESUMO

Reducing N rate without sacrificing grain yield is crucial for sustainable rice production in China. In this study, field experiments were conducted in 2016 and 2017 to determine whether the response of grain yield to reducing N rate varied between double-season rice (DSR) and single-season rice (SSR). Three N rates were applied for each rice crop, i.e. 150 kg ha-1 (N150, the locally recommended N rate), 90 kg ha-1 (N90), and 0 kg ha-1 (N0). Grain yield was lower under N90 than under N150 in DSR by 11-18%, whereas the difference was not significant in SSR. Grain yield under N0 was 36-63% lower in DSR than in SSR. There was a significant relationship between percentage change in grain yield comparing N90 to N150 with grain yield under N0. Furthermore, it was observed that grain yield under N0 was not significantly associated with growth duration but was closely associated with daily grain yield under N0, and the relationships of daily grain yield under N0 with seasonal average daily mean temperature and solar radiation were not significant. These results indicate that response of grain yield to reducing N rate was more sensitive in DSR compared to SSR due to lower soil N productivity. Growth duration and climatic conditions did not explain the difference in soil N productivity between DSR and SSR. The findings of this study should encourage more research into comparing the inherent traits of plants, especially the morphology and physiology of the root system, between DSR and SSR.


Assuntos
Agricultura/métodos , Grão Comestível/crescimento & desenvolvimento , Nitrogênio/metabolismo , Oryza/crescimento & desenvolvimento , Solo/química , China
16.
Cell Transplant ; 28(2): 170-175, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30545240

RESUMO

There has been no gold standard for intraoperative monitoring in carotid endarterectomy (CEA) till now. The purpose of the current study was to investigate the value of near-infrared spectroscopy (NIRS) monitoring in CEA and explore the thresholds for intraoperative cerebral hypoperfusion. Eighty-four consecutive patients who underwent CEA surgery in Xuan Wu Hospital of Capital Medical University from August 2015 to June 2016 were enrolled in this study. All patients were intraoperatively monitored by transcranial Doppler ultrasonography (TCD) and NIRS. Regional oxygen saturation (rSO2) monitored by NIRS and blood flow velocity of the middle cerebral artery (V-MCA) monitored by TCD were continuously recorded. Correlation analysis was conducted for NIRS and TCD monitoring values. Intraoperative shunting was performed in five patients according to the TCD monitoring results and surgeon preference. During clamping of the carotid artery, the Pearson correlation index between rSO2 and V-MCA was 0.581 (P<0.001). A cut-off of 12.3% decrease of rSO2 was identified as the optimal threshold for intraoperative hypoperfusion indicated by TCD monitoring, when the sensitivity and specificity were 74.6% and 91.7%, respectively, with a 0.609 Kappa value. Physical examination immediately after operation showed no ischemic injury occurred, and no death and stroke occurred during the postoperative hospitalization. Our study demonstrated that NIRS could serve as a favorable monitoring tool during CEA. A 12.3% decrease of rSO2 could be adopted as a reliable threshold for intraoperative cerebral hypoperfusion.

17.
Plant Biotechnol J ; 17(2): 397-409, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-29992702

RESUMO

Morella rubra, red bayberry, is an economically important fruit tree in south China. Here, we assembled the first high-quality genome for both a female and a male individual of red bayberry. The genome size was 313-Mb, and 90% sequences were assembled into eight pseudo chromosome molecules, with 32 493 predicted genes. By whole-genome comparison between the female and male and association analysis with sequences of bulked and individual DNA samples from female and male, a 59-Kb region determining female was identified and located on distal end of pseudochromosome 8, which contains abundant transposable element and seven putative genes, four of them are related to sex floral development. This 59-Kb female-specific region was likely to be derived from duplication and rearrangement of paralogous genes and retained non-recombinant in the female-specific region. Sex-specific molecular markers developed from candidate genes co-segregated with sex in a genetically diverse female and male germplasm. We propose sex determination follow the ZW model of female heterogamety. The genome sequence of red bayberry provides a valuable resource for plant sex chromosome evolution and also provides important insights for molecular biology, genetics and modern breeding in Myricaceae family.


Assuntos
Evolução Molecular , Genoma de Planta/genética , Myrica/genética , Mapeamento Cromossômico , Flores/genética , Flores/crescimento & desenvolvimento , Flores/fisiologia , Frutas/genética , Frutas/crescimento & desenvolvimento , Frutas/fisiologia , Marcadores Genéticos/genética , Anotação de Sequência Molecular , Myrica/crescimento & desenvolvimento , Myrica/fisiologia , Especificidade de Órgãos , Melhoramento Vegetal
18.
ACS Appl Mater Interfaces ; 10(49): 42837-42843, 2018 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-30430827

RESUMO

Encapsulation of luminescent perovskite quantum dots (QDs) into a solid matrix has been approved to be an efficient way to improve their stability. In this work, we reported a green encapsulation method to produce ultrastable CH3NH3PbBr3 QDs incorporated into the SiO2 matrix. Specifically, fresh-prepared CH3NH3PbBr3 QDs were covalently embedded into silica by an aqueous sol-gel method assisted with CH3NH3Br, which not only effectively inhibited the water-driven degradation of QDs through surface coordination, but also strongly stabilized the QDs in solid powder via concentration gradient. As far as we know, this silica encapsulation of perovskite QDs in aqueous environments is reported for the first time. Luminescent properties of perovskite QDs during the course of gelation as well as in resulting composite powder were investigated using steady-state and time-resolved spectroscopies, and a 2 wt % QD-doped sample treated with 11.5 mM of CH3NH3Br was demonstrated to be the optimal phosphor. The green-emissive phosphor had a PLQY of 60.3% and a full width at half maxima of ∼25 nm, exhibiting ultrahigh stability tested by cycle heating (120 °C), continuous heating (80 °C, 60 h), and light irradiation (450 nm light, 350 h). The phosphor was readily blended with polymers and applied as a color-converting layer on blue light-emitting diodes.

19.
Nanomaterials (Basel) ; 8(11)2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30388734

RESUMO

Improving the thermoelectric efficiency of a material requires a suitable ratio between electrical and thermal conductivity. Nanostructured graphene provides a possible route to improving thermoelectric efficiency. Bi-layer graphene was successfully prepared using pulsed laser deposition in this study. The size of graphene grains was controlled by adjusting the number of pulses. Raman spectra indicated that the graphene was bi-layer. Scanning electron microscopy (SEM) images clearly show that graphene changes from nanostructured to continuous films when more pulses are used during fabrication. Those results indicate that the size of the grains can be controlled between 39 and 182 nm. A detailed analysis of X-ray photoelectron spectra reveals that the sp² hybrid state is the main chemical state in carbon. The mobility is significantly affected by the grain size in graphene, and there exists a relatively stable region between 500 and 800 pulses. The observed phenomena originate from competition between decreasing resistance and increasing carrier concentration. These studies should be valuable for regulating grains sizes for thermoelectric applications of graphene.

20.
ACS Appl Mater Interfaces ; 10(44): 38538-38546, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30284805

RESUMO

To enable repeated intrinsic self-healing of wider cracks in polymers, a proof-of-concept approach is verified in the present work. It operates through two-way shape memory effect (SME)-aided intrinsic self-healing. Accordingly, a reversible C-ON bond is introduced into the main chain of crosslinked polyurethane (PU) containing an elastomeric dispersed phase (styrene-butadiene-styrene block copolymer, SBS). The PU/SBS blend was developed by the authors recently, and proved to possess an external stress-free two-way SME after programming. As a result, the thermal retractility offered by the SME coupled with the reversible C-ON bonds can be used for successive crack closure and remending based on synchronous fission/radical recombination of C-ON bonds. Moreover, multiwalled carbon nanotubes are incorporated to impart electrical conductivity to the insulating polymer. Repeated autonomic healing of wider cracks is thus achieved through narrowing of cracks followed by chemical rebonding under self-regulating Joule heating. No additional programming is needed after each healing event, which is superior to one-way SME-assisted self-healing. The outcomes set an example of integrating different stimuli-responsivities into single materials.

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