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"Perovskite / Carbon" interface has remained a key bottleneck for the hole-conductor-free perovskite solar cells based on carbon-electrode (CPSCs), due to problems like loose physics contact, defects, energy mismatch, poor chemical coupling, etc. A previous study shows that octylammonium iodide (OAI) blending in carbon paste induced a kind of "in-situ healing" effect for "perovskite / carbon" interface, and improved power conversion efficiency from ≈13% to >19%. Here the beneath mechanism is further explored by careful examination of the interaction between OAI molecule and carbon black (CB) nanoparticles. It comes to show that, the famous "CB adsorption" plays a key role during the "healing" processes. Due to CB adsorption behavior, the mass ratio between OAI and CB influences much on the healing effect. By suitably adjusting the mass ratio between OAI and CB, and increasing the light harvest of perovskite, an efficiency of 19.41% is achieved for the hole-conductor-free CPSCs. Device efficiency and the charge-extraction and recombination process are tracked with the storage period, continuous improvement appears for devices assembled by relatively higher CB mass. A kind of "slow-release effect" is revealed during the OAI-induced "in-situ healing" process, which is caused by the famous "CB adsorption" behavior.
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Terahertz (THz) metasurfaces have opened up a new avenue for the THz wavefront modulation. However, high-efficient and low-cost fabrication of THz metasurfaces remains a great challenge today. Here, quasi-capsule-shaped polarization-multiplexed holographic THz metasurfaces were printed by a beam-shaped femtosecond laser. The laser beam was spatially modulated by holograms of optimized cylindrical lens loaded on a spatial light modulator (SLM). The size of quasi-capsule apertures can be exquisitely and flexibly controlled by adjusting the focal length in holograms, pulse energy, and pulse number. Based on near-field diffraction and Burch encoding, an array of 100 × 100 basic unit apertures were initially designed, and a polarization-multiplexed THz metasurface was finally printed with a dimension of 8â mm × 8â mm. The function of polarization multiplexing was demonstrated, by which two kinds of images were reconstructed in response to X and Y-polarization THz waves, respectively. The present work highlights a great leap in fabrication method for THz metasurfaces and hopefully stimulates the development of miniaturized and integrated THz systems.
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We previously reported that prolonged exposure to an enriched environment (EE) enhances hippocampal synaptic plasticity, with one of the significant mechanistic pathways being activation of ß2-adrenergic receptor (ß2-AR) signaling, thereby mitigating the synaptotoxic effects of soluble oligomers of amyloid ß-protein (oAß). However, the detailed mechanism remained elusive. In this work, we recorded field excitatory postsynaptic potentials (fEPSP) in the CA1 region of mouse hippocampal slices treated with or without toxic Aß-species. We found that pharmacological activation of ß2-AR, but not ß1-AR, selectively mimicked the effects of EE in enhancing LTP and preventing oAß-induced synaptic dysfunction. Mechanistic analyses showed that certain histone deacetylase (HDAC) inhibitors mimicked the benefits of EE, but this was not seen in ß2-AR knockout mice, suggesting that activating ß2-AR prevents oAß-mediated synaptic dysfunction via changes in histone acetylation. EE or activation of ß-ARs each decreased HDAC2, whereas Aß oligomers increased HDAC2 levels in the hippocampus. Further, oAß-induced inflammatory effects and neurite degeneration were prevented by either ß2-AR agonists or certain specific HDAC inhibitors. These preclinical results suggest that activation of ß2-AR is a novel potential therapeutic strategy to mitigate oAß-mediated features of AD.
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Peptídeos beta-Amiloides , Hipocampo , Camundongos , Animais , Peptídeos beta-Amiloides/toxicidade , Peptídeos beta-Amiloides/metabolismo , Transdução de Sinais , Epigênese Genética , Camundongos KnockoutRESUMO
INTRODUCTION: Recent research on the gut deepens people's understanding of the role of gut microbe-metabolites in longevity. However, most of the longevity population is female, and the gut microbe-metabolites associated with longevity in women remain unknown. Here, we hypothesize that the gut microbe-metabolite levels differed between the longevity women (LW, age ≥90) and the elderly women (EW, 60 < age <90). METHODS: We performed a cross-sectional study of 22 women in Guangxi longevity areas. 16S rRNA full-length sequencing, bioinformatic analysis, and nuclear magnetic resonance hydrogen spectra were determined to analyze the gut microbiota, microbial pathways, and fecal metabolites. We evaluated significant differences and relationships in gut microbe-metabolites and microbial pathways using the Mann-Whitney test and Spearman correlation, respectively. RESULTS: The EW experienced gut dysbiosis characterized by a higher Firmicutes/Bacteroidetes (F/B) value. The LW showed a higher abundance of Bacteroides and Alistipes, which might support health maintenance. Moreover, LW enriched alanine, aspartate, and glutamate metabolism, histidine metabolism, and pyruvate metabolism, leading to major changes in histidine, fumaric acid, acetate, valine, and aspartate. Interestingly, the most valuable metabolic pathway based on differential fecal metabolites confirmed the KEGG microbial pathway "alanine, aspartate, and glutamate metabolism" enriched in LW. Impressively, Bacteroides and Alistipes were positively correlated with alanine, aspartate, and glutamate metabolism, thus improving the level of aspartate, which could be a particular pathway related to longevity. CONCLUSION: The enriched gut genus and microbial pathways in LW showed a significant correlation, which might mediate the production of metabolites related to longevity.
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Ácido Aspártico , Microbioma Gastrointestinal , Idoso , Humanos , Feminino , China , Estudos Transversais , Histidina , RNA Ribossômico 16S/genética , Alanina , GlutamatosRESUMO
Total astragalus saponins (TAS) are the main active components of astragali radix, and have potent anti-hepatic fibrosis effect. However, the therapeutic efficacy of TAS and their potential mechanisms in the treatment of primary sclerosing cholangitis (PSC) remain unclear. In this study, two mouse models of PSC, including 3,5-Diethoxycarbonyl-1,4-Dihydro-2,4,6-Collidine (DDC)-induced PSC and Mdr2-/- spontaneous PSC, and the Tgr5-/- mice were used to investigate the therapeutic effect and mechanisms of TAS. Treatment with TAS, particularly with a dose of 56 mg/kg, significantly ameliorated the PSC-related liver injury, cholestasis, collagen deposition, ductular reaction (DR), and fibrosis in the DDC-induced and Mdr2-/-spontaneous PSC mice. Furthermore, treatment with TAS significantly mitigated the PSC-related inflammatory responses in vivo and HIBEpiC cells by inhibiting the expression of TNF-α, IL-6, and IL-1ß. Mechanistically, treatment with TAS rescued the PSC-decreased hepatic TGR5 expression to attenuate the NF-κB p65 phosphorylation. Notably, the therapeutic efficacy of TAS on PSC in DDC-induced mice was abrogated in Tgr5-/- mice, suggesting the anti-PSC effect of TAS may depend on enhancing TGR5 expression. In conclusion, TAS ameliorated DR, inflammation and liver fibrosis in both models of PSC mice by rescuing TGR5 expression. Our findings may aid in the design of new therapeutic strategies for the treatment of PSC.
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Despite growing interest in predicting plant phenological shifts, advanced spring phenology by global climate change remains debated. Evidence documenting either small or large advancement of spring phenology to rising temperature over the spatio-temporal scales implies a potential existence of a thermal threshold in the responses of forests to global warming. We collected a unique data set of xylem cell-wall-thickening onset dates in 20 coniferous species covering a broad mean annual temperature (MAT) gradient (-3.05 to 22.9°C) across the Northern Hemisphere (latitudes 23°-66° N). Along the MAT gradient, we identified a threshold temperature (using segmented regression) of 4.9 ± 1.1°C, above which the response of xylem phenology to rising temperatures significantly decline. This threshold separates the Northern Hemisphere conifers into cold and warm thermal niches, with MAT and spring forcing being the primary drivers for the onset dates (estimated by linear and Bayesian mixed-effect models), respectively. The identified thermal threshold should be integrated into the Earth-System-Models for a better understanding of spring phenology in response to global warming and an improved prediction of global climate-carbon feedbacks.
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Traqueófitas , Teorema de Bayes , Florestas , Temperatura Baixa , Temperatura , Mudança Climática , Estações do AnoRESUMO
BACKGROUND: Individual metals have been linked to sex hormones disruption, but the associations of metals mixture are rarely examined among children. METHODS: A total of 1060 participants of 6-19-year-old who participated in the National Health and Nutrition Examination Survey (2013-2016) were included. Eighteen metals were quantified in the whole blood and urine. Sex hormones were measured in serum, including total testosterone (TT), estradiol (E2), and sex hormone binding globulin (SHBG). In addition, free androgen index (FAI) and the ratio of TT to E2 were calculated. Bayesian kernel machine regression and latent class analysis were performed to assess the associations of metals mixture and exposure patterns of metals at varied levels with sex hormones while adjusting for selected covariates. All analyses were conducted by sex-age and sex-puberty groups to explore the potential sex-dimorphic effects. RESULTS: Exposure to metals mixture was associated with elevated levels of FAI and E2 among 12-19 years old girls. Moreover, the exposure pattern of metals that was characterized by high levels of blood and urinary cadmium, blood manganese, and urinary cobalt was associated with elevated E2 and reduced TT/E2 levels among girls of 12-19 years old. However, the associations of metals mixture with sex hormones were overall nonsignificant among boys. Nevertheless, metals exposure pattern that was characterized by high levels of blood lead, urinary barium, strontium, and lead but comparatively low levels of the other metals was consistently associated with reduced levels of FAI and E2 but elevated levels of TT/E2 and SHBG among boys of 12-19 years old. CONCLUSION: Metals mixture and exposure patterns that were dominated by high levels of certain metals were associated with sex hormones imbalance among 12-19 years old children in a sex-dimorphic pattern, with the identified individual metals that drove the associations of metals mixture varied by sex.
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Hormônios Esteroides Gonadais , Testosterona , Adolescente , Criança , Feminino , Humanos , Masculino , Adulto Jovem , Teorema de Bayes , Estradiol , Metais/toxicidade , Metais/metabolismo , Inquéritos Nutricionais , Globulina de Ligação a Hormônio Sexual/metabolismoRESUMO
BACKGROUND: During high-cell-density culture of Lactobacillus fermentum, the optimal pH is often maintained by adding NaOH. During cultivation at controlled pH, L. fermentum experiences osmotic stress due to the continuous accumulation of sodium lactate as a neutralizer product, affecting its survival in subsequent processing. The purpose of this study was to evaluate the nutrient consumption patterns of L. fermentum ATCC 14931 under sodium lactate stress and to screen nutrients that help it resist osmotic stress. RESULTS: The consumption and consumption rates of amino acids, purines, pyrimidines, vitamins, and metal ions were analyzed in chemically defined media containing 0.13, 0.31, or 0.62 mm L-1 sodium lactate. The highest consumption rates were found for arginine, guanine, folic acid, and Mn2+ , and the most consumed nutrients were glutamate + glutamine, guanine, ascorbic acid, and Na+ . Arginine 2.58 mm L-1 , guanine 0.23 mm L-1 , and Mn2+ 0.25 mm L-1 were added to the medium at sodium lactate concentrations of 0.13 and 0.62 mm L-1 , and arginine 2.58 mm L-1 , guanine 0.26 mm L-1 , and Mn2+ 0.25 mm L-1 at a sodium lactate concentration of 0.31 mm L-1 . The viable cell counts of L. fermentum ATCC 14931 were approximately 1.02-fold (P < 0.05) of the counts observed in control medium at all three concentrations of sodium lactate. CONCLUSION: The present results suggest that certain nutrients accelerate the growth of L. fermentum under sodium lactate stress and enhance its resistance to this adverse condition. © 2022 Society of Chemical Industry.
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Limosilactobacillus fermentum , Lactato de Sódio , Aminoácidos , Arginina/metabolismo , NutrientesRESUMO
Online education brings more possibilities for personalized learning, in which identifying the cognitive state of learners is conducive to better providing learning services. Cognitive diagnosis is an effective measurement to assess the cognitive state of students through response data of answering the problems(e.g., right or wrong). Generally, the cognitive diagnosis framework includes the mastery of skills required by a specified problem and the aggregation of skills. The current multi-skill aggregation methods are mainly divided into conjunctive and compensatory methods and generally considered that each skill has the same effect on the correct response. However, in practical learning situations, there may be more complex interactions between skills, in which each skill has different weight impacting the final result. To this end, this paper proposes a generalized multi-skill aggregation method based on the Sugeno integral (SI-GAM) and introduces fuzzy measures to characterize the complex interactions between skills. We also provide a new idea for modeling multi-strategy problems. The cognitive diagnosis process is implemented by a more general and interpretable aggregation method. Finally, the feasibility and effectiveness of the model are verified on synthetic and real-world datasets.
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Acidic CO2 reduction (CO2 R) holds promise for the synthesis of low-carbon-footprint chemicals using renewable electricity. However, the corrosion of catalysts in strong acids causes severe hydrogen evolution and rapid deterioration of CO2 R performance. Here, by coating catalysts with an electrically nonconductive nanoporous SiC-NafionTM layer, a near-neutral pH was stabilized on catalyst surfaces, thereby protecting the catalysts against corrosion for durable CO2 R in strong acids. Electrode microstructures played a critical role in regulating ion diffusion and stabilizing electrohydrodynamic flows near catalyst surfaces. This surface-coating strategy was applied to three catalysts, SnBi, Ag, and Cu, and they exhibited high activity over extended CO2 R operation in strong acids. Using a stratified SiC-NafionTM /SnBi/polytetrafluoroethylene (PTFE) electrode, constant production of formic acid was achieved with a single-pass carbon efficiency of >75 % and Faradaic efficiency of >90 % at 100â mA cm-2 over 125â h at pHâ 1.
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An anisotropic plasmonic surface of nanoellipsoid arrays is successfully fabricated on an Au film using slit-shaping-based femtosecond laser nanoprinting. The size and orientation of the nanoellipsoid can be exquisitely and flexibly controlled by adjusting the width and direction of the slit and the laser pulse energy. By dark-field optical micro-spectroscopy, anisotropic plasmonic color rendering as well as resonant light scattering from the lateral and vertical modes are experimentally and theoretically investigated in the visible spectral range. In addition, prospective use in the fields of steganographic encryption and multidimensional optical multiplexing is also proposed.
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Altered migration and immune responses of dendritic cells (DCs) lead to inflammatory and autoimmune diseases. Our studies demonstrated that ß-arrestin 2 deficiency promoted migration and cytokine production of mouse bone marrow-derived DCs. We further found that ß-arrestin 2 directly interacted with Zbtb46, a DC-specific transcription factor. What's more, our results suggested that the interaction between ß-arrestin 2 and Zbtb46 might negatively regulate DC migration. Using RNA sequencing, we indicated that genes CD74, NR4A1, and ZFP36 might be the target genes regulated by the interaction between ß-arrestin 2 and Zbtb46. Mice with selective deficiency of ß-arrestin 2 in DCs developed severer experimental autoimmune encephalomyelitis with more DC infiltration in the CNS and increased IL-6 in serum. In the systemic lupus erythematosus mice model, Arrb2fl/fl Itgax-cre+ mice were prone to exacerbation of lupus nephritis with a higher level of IL-6 and DC accumulation. Taken together, our study identified ß-arrestin 2 as a new regulator of DC migration and immune properties, providing new insights into the mechanisms underlying the development of autoimmune disease.
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Células Dendríticas/imunologia , Encefalomielite Autoimune Experimental/imunologia , Fatores de Transcrição/metabolismo , beta-Arrestina 2/metabolismo , Animais , Antígenos de Diferenciação de Linfócitos B/genética , Diferenciação Celular , Movimento Celular/genética , Células Cultivadas , Citocinas/metabolismo , Encefalomielite Autoimune Experimental/genética , Regulação da Expressão Gênica , Antígenos de Histocompatibilidade Classe II/genética , Interleucina-6/sangue , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Ligação Proteica , Análise de Sequência de RNA , Tristetraprolina/genética , beta-Arrestina 1/genética , beta-Arrestina 1/metabolismo , beta-Arrestina 2/genéticaRESUMO
Two experiments investigated the mental representations of objects' location in a virtual nested environment. In Experiment 1, participants learned the locations of objects (buildings or related accessories) in an exterior environment and then learned the locations of objects inside one of the centrally located buildings (interior environment). Participants completed judgments of relative direction in which the imagined heading was established by pairs of objects from the interior environment and the target was one of the objects in the exterior environment. Performance was best for the imagined heading and allocentric target direction parallel to the learning heading of the exterior environment, but the effect of allocentric target direction was only significant for the imagined headings aligned with the reference axes of both environments; in addition, performance was best along the front-back egocentric axis (parallel to the imagined heading). Experiment 2 used the same learning procedure. After learning, the viewpoint was moved from the exterior environment along a smooth path into a side entrance of the building/interior environment. There participants saw the array of interior objects in the orientation consistent with their movement (correct cue), the array of objects in an orientation inconsistent with their movement (misleading cue), or no array of objects (no cue), and then pointed to objects in the exterior environment. Pointing performance was best for the correct-cue condition. Collectively the results indicated that memories of nested spaces are segregated by spatial conceptual level, and that spatial relations between levels are specified in terms of the dominant reference directions.
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Memória , Percepção Espacial , Humanos , Julgamento , Aprendizagem , MovimentoRESUMO
Verticillium wilt, caused by Verticillium dahliae, is a devastating disease for many important crops, including cotton. Kiwellins (KWLs), a group of cysteine-rich proteins synthesized in many plants, have been shown to be involved in response to various phytopathogens. To evaluate genes for their function in resistance to Verticillium wilt, we investigated KWL homologs in cotton. Thirty-five KWL genes (GhKWLs) were identified from the genome of upland cotton (Gossypium hirsutum). Among them, GhKWL1 was shown to be localized in nucleus and cytosol, and its gene expression is induced by the infection of V. dahliae. We revealed that GhKWL1 was a positive regulator of GhERF105. Silencing of GhKWL1 resulted in a decrease, whereas overexpression led to an increase in resistance of transgenic plants to Verticillium wilt. Interestingly, through binding to GhKWL1, the pathogenic effector protein VdISC1 produced by V. dahliae could impair the defense response mediated by GhKWL1. Therefore, our study suggests there is a GhKWL1-mediated defense response in cotton, which can be hijacked by V. dahliae through the interaction of VdISC1 with GhKWL1.
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Ascomicetos , Proteínas Fúngicas , Regulação Fúngica da Expressão Gênica , Gossypium , Doenças das Plantas , Fatores de Transcrição , Regulação para Cima , Fatores de Virulência , Ascomicetos/genética , Ascomicetos/metabolismo , Ascomicetos/patogenicidade , Proteínas Fúngicas/biossíntese , Proteínas Fúngicas/genética , Gossypium/genética , Gossypium/metabolismo , Gossypium/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Fatores de Virulência/biossíntese , Fatores de Virulência/genéticaRESUMO
The rapid emergence of bacterial coinfection caused by cytosolic bacteria has become a huge threat to public health worldwide. Past efforts have been devoted to discover the broad-spectrum antibiotics, while the emergence of antibiotic resistance encourages the development of antibacterial agents. In essence, bacterial virulence is a factor in antibiotic tolerance. However, the discovery and development of new antibacterial drugs and special antitoxin drugs is much more difficult in the antibiotic resistance era. Herein, we hypothesize that antitoxin hemolytic activity can serve as a screening principle to select antibacterial drugs to combat coinfection from natural products. Being the most abundant natural drug of plant origins, flavonoids were selected to assess the ability of antibacterial coinfections in this paper. Firstly, we note that four flavonoids, namely, baicalin, catechin, kaempferol, and quercetin, have previously exhibited antibacterial abilities. Then, we found that baicalin, kaempferol, and quercetin have better inhibitions of hemolytic activity of Hla than catechin. In addition, kaempferol and quercetin, have therapeutic effectivity for the coinfections of Staphylococcus aureus and Pseudomonas aeruginosa in vitro and in vivo. Finally, our results indicated that kaempferol and quercetin therapied the bacterial coinfection by inhibiting S. aureus α-hemolysin (Hla) and reduced the host inflammatory response. These results suggest that antitoxins may play a promising role as a potential target for screening flavonoids to combat bacterial coinfection.
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Antibacterianos , Proteínas de Bactérias , Flavonoides , Proteínas Hemolisinas , Pseudomonas aeruginosa/metabolismo , Staphylococcus aureus/metabolismo , Antibacterianos/química , Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Avaliação Pré-Clínica de Medicamentos , Flavonoides/química , Flavonoides/farmacologia , Proteínas Hemolisinas/antagonistas & inibidores , Proteínas Hemolisinas/metabolismoRESUMO
We report a facile top-flat square nanosecond (ns) laser direct writing ablation technique in a thin silver film substrate to fabricate the silver square-shaped cell structure of flexible transparent electrodes. Square silver cell structures feature smooth surface morphology, excellent edge definition, mechanical stability, strong adhesion to the substrate, and favorable resistance and transparency. In particular, this strategy enables fabrication of a high square-shaped cell areal density (ablated square cell to the total area) Ag mesh, substantially improving transparency ($ {\gt} {85}\% $>85%) without considerably sacrificing conductivity ($ {\lt} {5}\;\Omega \;{{\rm sq}^{ - 1}}$<5Ωsq-1 unit of resistance). Consequently, the proposed metallic square-shaped structure shows compatibility with a polyethylene naphthalate flexible substrate for silver-based wearable electronic devices without any protective layer over the electrodes.
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Laser-induced periodic surface structures (LIPSS) are a universal phenomenon that can allow tailoring nanoelectronics and nanophotonics devices. However, there is an issue about the formation mechanism of LIPSS, and the current research mainly focuses on the formation process of the individual structures, such as the low spatial frequency LIPSS (LSFL), sub-wavelength structures, and laser-induced periodic annular surface structures (LIPASS). A whole process formation picture of the series of these periodic structures is still missing. In this study, a pump-probing setup is applied to ensure the real-time and in situ monitoring of surface modification under different pulse numbers. LSFL firstly appears on the surface after two laser shots, and then, laser-induced orthogonal periodic structures (LIOPS) become the dominant morphology after five laser shots, which result from the local field enhancement of the surface ripples. As the laser shots increase, the LSFL split leads to the formation of nanopillars, and the formation of the nanopillars under the surface LSFL (after ten laser shots) is due to the transition between the LSFL and HSFL with an orientation parallel to the laser polarization. A dip surrounded by annular periodic fringes after 50 laser shots is observed, which is due to the interference of the incident laser field and the reflected laser field on the crater surface. Finally, a direct writing technique for fabrication of nano-gratings is also reported.
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MOTIVATION: The development of high-throughput sequencing technology has made it possible for more and more researchers to use population sequencing data to mine genes associated with specific traits. However, the massive amounts of sequencing data have also brought new challenges to the researchers. The question of how to browse population genomic data in an easy and intuitive manner must be addressed. Web-based genome browsers allow user to conveniently view the results of genomic analyses, but heavy usage can reduce the response speed of the webpage, which limits its usefulness in the display of large-scale genome data. IndexedDB technology is a good solution to this problem; it supports web browsers and so creates local databases. In this way, data can be read from the local storage, achieving a smooth display of population genomic data. RESULTS: PopGeV has the following characteristics. First, it uses a new encoding method for compression of population SNP and INDEL data. IndexedDB technology is used to download the results to local storage so that users can browse the results smoothly even when the network traffic is heavy. Second, PopGeV identify similar genomic regions between two individuals based on SNP data. Population diversity indexes are calculated when comparing two populations. Third, user defined annotation information can be integrated for user-friendly mining of gene functions. Simulation shows that PopGeV can smoothly display analysis results of population genome containing over 500 individuals with 2 millions SNP data. AVAILABILITY AND IMPLEMENTATION: PopGeV is available at www.soyomics.com/popgev/ CONTACT: yuanxh@iga.ac.cn.
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Bases de Dados Factuais , Genoma Humano , Mutação INDEL/genética , Metagenômica/métodos , Polimorfismo de Nucleotídeo Único/genética , Navegador , Biologia Computacional/métodos , Humanos , Internet , Interface Usuário-ComputadorRESUMO
Correction for 'In situ study of the catalytic mechanism for the oxygen reduction reaction on a polypyrrole modified carbon supported cobalt hydroxide cathode in direct borohydride fuel cells' by Haiying Qin et al., Phys. Chem. Chem. Phys., 2013, 15, 9070-9074.
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A new method of terahertz (THz) imaging based on the mean absorption is proposed. Terahertz radiation is an electromagnetic radiation in the range between millimeter waves and far infrared. THz pulse imaging emerges as a novel tool in many fields because of its low energy and non-ionizing character, such as material, chemical, biological medicine and food safety. A character of THz imaging technique is it can get large amount of information. How to extract the useful parameter from the large amount of information and reconstruct sample's image is a key technology in THz imaging. Some efforts have been done for advanced visualization methods to extract the information of interest from the raw data. Both time domain and frequency domain visualization methods can be applied to extract information on the physical properties of samples from THz imaging raw data. The process of extracting useful parameter from raw data of the new method based on the mean absorption was given in this article. This method relates to the sample absorption and thickness, it delivers good signal to noise ratio in the images, and the dispersion effects are cancelled. A paper with a "THz" shape hole was taken as the sample to do the experiment. Traditional THz amplitude imaging methods in time domain and frequency domain are used to achieve the sample's image, such as relative reduction of pulse maximum imaging method, relative power loss imaging method, and relative power loss at specific frequency imaging method. The sample's information that reflected by these methods and the characteristics of these methods are discussed. The method base on the mean absorption within a certain frequency is also used to reconstruct sample's image. The experimental results show that this new method can well reflect the true information of the sample. And it can achieve a clearer image than the other traditional THz amplitude imaging methods. All the experimental results and theoretical analyses indicate that the method base on the mean absorption within a certain frequency can reflects sample absorb and thickness information, it can achieve good signal to noise ratio in the images. Because the absorption is mean absorption within in a certain frequency, so the method proposed in this article is especially suitable for samples with simple structure. And this new method can be a useful added tool for the other traditional THz amplitude imaging methods.