57 research outputs found

    Identification of candidate genes and clarification of the maintenance of the green pericarp of weedy rice grains

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    The weedy rice (Oryza sativa f. spontanea) pericarp has diverse colors (e.g., purple, red, light-red, and white). However, research on pericarp colors has focused on red and purple, but not green. Unlike many other common weedy rice resources, LM8 has a green pericarp at maturity. In this study, the coloration of the LM8 pericarp was evaluated at the cellular and genetic levels. First, an examination of their ultrastructure indicated that LM8 chloroplasts were normal regarding plastid development and they contained many plastoglobules from the early immature stage to maturity. Analyses of transcriptome profiles and differentially expressed genes revealed that most chlorophyll (Chl) degradation-related genes in LM8 were expressed at lower levels than Chl a/b cycle-related genes in mature pericarps, suggesting that the green LM8 pericarp was associated with inhibited Chl degradation in intact chloroplasts. Second, the F2 generation derived from a cross between LM8 (green pericarp) and SLG (white pericarp) had a pericarp color segregation ratio of 9:3:4 (green:brown:white). The bulked segregant analysis of the F2 populations resulted in the identification of 12 known genes in the chromosome 3 and 4 hotspot regions as candidate genes related to Chl metabolism in the rice pericarp. The RNA-seq and sqRT-PCR assays indicated that the expression of the Chl a/b cycle-related structural gene DVR (encoding divinyl reductase) was sharply up-regulated. Moreover, genes encoding magnesium-chelatase subunit D and the light-harvesting Chl a/b-binding protein were transcriptionally active in the fully ripened dry pericarp. Regarding the ethylene signal transduction pathway, the CTR (encoding an ethylene-responsive protein kinase) and ERF (encoding an ethylene-responsive factor) genes expression profiles were determined. The findings of this study highlight the regulatory roles of Chl biosynthesis- and degradation-related genes influencing Chl accumulation during the maturation of the LM8 pericarp

    Disposable Electrochemical Aptasensor Based on Graphene Oxide-DNA Complex as Signal Amplifier towards Ultrasensitive Detection of Ochratoxin A

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    Signal amplification is crucial in developing a reliable disposable screen-printed carbon electrodes (SPCEs)-based biosensor for analyte detection with a narrow detection window. This work demonstrated a novel label-free electrochemical aptasensor based on SPCEs for the ultrasensitive detection of ochratoxin A (OTA). The graphene oxide-DNA (GO-DNA) complex as a signal amplifier with easy preparation was investigated for the first time. The proposed aptasensor based on the SPCEs/GO/cDNA-aptamer/3D-rGO-AuNPs structure was formed through the hybridization of aptamer-linked 3D-rGO/AuNPs and its complementary DNA-linked GO (GO-cDNA). The presence of OTA was discerned by its specific aptamer forming a curled OTA-aptamer complex and releasing the GO-cDNA from the surface of SPCEs. The resulting OTA-aptamer complex hindered interfacial electron transfer on the sensing surface, leading to the decreased peak current. The GO-cDNA further amplified the peak current change. This electrochemical aptasensor showed a low limit of detection of 5 fg/mL as well as good reproducibility with the relative standard deviation (RSD) of 4.38%. Moreover, the detection result of OTA in the rice and oat samples was comparable with that of the enzyme-linked immunosorbent assay (ELISA) kit. In general, the OTA aptasensor used in this work with convenient preparation, low-cost, good selectivity, high sensitivity and acceptable reproducibility can be proposed as a reliable point-of-care (POC) technique for OTA determination

    Analysis Of Heat Transfer And Transport Processes In Sofcs Involving Internal Reforming Reactions

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    The heat transfer rates in solid oxide fuel cells (SOFCs) are controlled by various operating and design parameters and have significant effects on chemical reactions and coupled transport processes. In this article, the considered composite duct consists of a porous anode layer for the internal reforming reactions of methane, the fuel gas flow duct, and the solid plate. A fully three-dimensional calculation code is employed to analyze heat transfer and combined effects of internal reforming/electrochemical reactions on the coupled transport processes, with the purpose to reveal the importance of various parameters. The results show that the internal reforming reactions are mostly confined within 200-300 mu m into the anode porous layer and almost no methane reaches the triple phase boundary (TPB) after the first 10% of the duct length. The operating temperatures have significant effects on the chemical reactions, fuel gas distribution, and overall performance. This study also evaluated the convective heat transfer in the fuel flow duct, in terms of interface thermal boundary/temperature gradients and convective heat transfer coefficients

    Computational fluid dynamics model development on transport phenomena coupling with reactions in intermediate temperature solid oxide fuel cells

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    A 3D model is developed to describe an anode-supported planar solid oxide fuel cell (SOFC), by ANSYS/Fluent evaluating reactions including methane steam reforming (MSR)/water-gas shift (WGSR) reactions in thick anode layer and H-2-O-2/CO-O-2 electrochemical reactions in anode active layer, coupled with heat, mass species, momentum, and ion/electron charges transport processes in SOFC. The predicted results indicate that electron/ion exchange appears in the very thin region in active layers (0.018 mm in anode and 0.01 mm in cathode), based on three phase boundary, operating temperature and concentration of reactants (mainly H-2). Active polarization happening in active layers dominates over concentration and ohmic losses. High gradient of current density exists near interface between electrode and solid conductor due to the block by gas channel. It is also found the reaction rates of MSR and WGSR along main flow direction and cell thickness direction decrease due to low concentration of fuel (CH4) caused by mass consumption. With increasing operating temperature from 978 K to 1088 K, the current density and the reaction rate of MSR are increased by 10.8% and 5.4%, respectively. While ion current density is 52.9% higher than in standard case, and H-2 is consumed by 5.1% more when ion conductivity is doubled. CO-O-2 has been considered in charge transfer reaction in anode active layer and it is found that the current density and species distributions are not sensitive, but WGSR reaction will be forced backwards to supply more CO for CO-O-2 electrochemical reaction. (V) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798789

    CFD Approach to Analyze Transport Phenomena Coupled Chemical Reactions Relevant for Methane Reformers

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    Various transport phenomena in conjunction with chemical reactions are strongly affected by reformer configurations and the properties of the involved porous catalyst layers. The considered composite duct is relevant for a methane steam reformer and consists of a porous layer for the catalytic chemical reactions, the fuel gas flow duct and the solid plate. In this paper, a fully three-dimensional calculation method is developed to simulate and analyse the reforming reactions of methane, with the purpose of revealing the importance of design and operating parameters. The reformer conditions, such as mass balances associated with the reforming reactions and gas permeation to/from the porous catalyst reforming layer, are applied in the analysis. The results show that the characteristic parameters have significant effects on the transport phenomena and the overall reforming reaction performance

    Root Traits and Soil Bacterial Composition Explain the Rhizosphere Effects along a Chronosequence of Rubber Plantations

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    Rubber tree plantations (Hevea brasiliensis) are expanding into the tropical regions of southwest China to ensure production to meet the growing demand for latex. The effects of long-term plantations on soil carbon processes are still unclear. Also, the effects of the plant’s rhizosphere on the decomposition of soil organic matter (SOM) play a crucial role in predicting soil carbon dynamics. The rhizosphere and soils corresponding to a chronosequence of ages (4, 15 and 30 years) of rubber plantations were collected and incubated to determine the effect of the rhizosphere (RE) on SOM decomposition. We also examined the soil physicochemical properties; bacterial community structure; and root morphological, chemical, and physiological traits to further explore the underlying mechanisms of the RE on SOM decomposition. The REs on SOM decomposition varied significantly in the different age classes of the rubber plantations, and the higher the REs on SOM decomposition in an older plantation might limit the accumulation of organic carbon in the soil. Root traits, including the specific root length, root nitrogen content, and root carbon/nitrogen ratio, varied significantly in response to the plantation age and explained more of the variance in the RE on SOM decomposition than the soil and microbial properties. Due to the changing root morphological and chemical traits along the age chronosequence, the rhizosphere bacterial community composition tended to shift the carbon utilisation strategy and the bulk soil nitrogen content decreased. These variations also affected the RE on SOM decomposition. Our results indicate that the development of rubber plantations would prevent soil carbon accumulation, especially in the rhizosphere, by increasing the RE on SOM decomposition, which would be predicated by root morphological and chemical traits

    Synthesis and Characterization of Photo-Responsive Thermotropic Liquid Crystals Based on Azobenzene

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    A series of new thermotropic liquid crystals (LCs) containing azobenzene units was synthesized. The structures of the compounds were characterized by means of NMR and FTIR spectroscopy. Their mesomorphic behaviors were investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Based on the POM and DSC measurements, the optical properties of the Razo-ester were tested using UV-vis spectroscopy. The azobenzene side chain displayed a strong ability to influence the formation of thermotropic LCs

    Data from: Portable bacteria-capturing chip for direct surface-enhanced Raman scattering identification of urinary tract infection pathogens

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    Acute urinary tract infections (UTIs) are one of the most common nosocomial bacterial infections, which affect almost 50% of the population at least once in their lifetime. UTIs may lead to lethal consequences if they are left undiagnosed and untreated properly. Early, rapid and accurate uropathogens detection methods play a pivotal role in clinical process. In this work, a portable bacteria-grasping surface-enhanced Raman scattering (SERS) chip for identification of three species of uropathogens (E. coli CFT 073, P. aeruginosa PAO1, and P. mirabilis PRM1) directly from culture matrix was reported. The chip was firstly modified with a positively-charged NH3+ group, which enable itself grasp the negatively-charged bacterial cells through the electrostatic adsorption principle. After the bacterial cells were captured by the chip, concentrated Ag nanoparticles (NPs) were used to obtain their Raman fingerprint spectra with recognizable characteristic peaks and good reproducibility. With the help of chemometric method such as discriminant analysis (DA), the SERS based chip allows a rapid, successful identification of three species of UTI bacteria with a minimal bacterial concentration (105 cells/mL) required for clinical diagnostics. In addition, this chip could spot the bacterial SERS fingerprints information directly from LB culture medium and artificial urine without sample pre-treatment. The portable bacteria-grasping SERS based chip provides a possibility for fast and easy detection of uropathogens, and viability of future development in healthcare applications

    A nomogram for predicting sepsis-associated delirium: a retrospective study in MIMIC III

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    Abstract Objective To develop a nomogram for predicting the occurrence of sepsis-associated delirium (SAD). Materials and methods Data from a total of 642 patients were retrieved from the Medical Information Mart for Intensive Care (MIMIC III) database to build a prediction model. Multivariate logistic regression was performed to identify independent predictors and establish a nomogram to predict the occurrence of SAD. The performance of the nomogram was assessed in terms of discrimination and calibration by bootstrapping with 1000 resamples. Results Multivariate logistic regression identified 4 independent predictors for patients with SAD, including Sepsis-related Organ Failure Assessment(SOFA) (p = 0.004; OR: 1.131; 95% CI 1.040 to 1.231), mechanical ventilation (P < 0.001; OR: 3.710; 95% CI 2.452 to 5.676), phosphate (P = 0.047; OR: 1.165; 95% CI 1.003 to 1.358), and lactate (P = 0.023; OR: 1.135; 95% CI 1.021 to 1.270) within 24 h of intensive care unit (ICU) admission. The area under the curve (AUC) of the predictive model was 0.742 in the training set and 0.713 in the validation set. The Hosmer − Lemeshow test showed that the model was a good fit (p = 0.471). The calibration curve of the predictive model was close to the ideal curve in both the training and validation sets. The DCA curve also showed that the predictive nomogram was clinically useful. Conclusion We constructed a nomogram for the personalized prediction of delirium in sepsis patients, which had satisfactory performance and clinical utility and thus could help clinicians identify patients with SAD in a timely manner, perform early intervention, and improve their neurological outcomes
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