260 research outputs found

    DNA-Programmed Modular Assembly of Cyclic and Linear Nanoarrays for the Synthesis of Two-Dimensional Conducting Polymers

    No full text
    Nanometer-scale arrays of conducting polymers were prepared on scaffolds of self-assembling DNA modules. A series of DNA oligomers was prepared, each containing six 2,5-bis­(2-thienyl)­pyrrole (SNS) monomer units linked covalently to N4 atoms of alternating cytosines placed between leading and trailing 12-nucleobase recognition sequences. These DNA modules were encoded so the recognition sequences would uniquely associate through Watson–Crick assembly to form closed-cycle or linear arrays of aligned SNS monomers. The melting behavior and electrophoretic migration of these assemblies showed cooperative formation of multicomponent arrays containing two to five DNA modules (i.e., 12–30 SNS monomers). The treatment of these arrays with horseradish peroxidase and H<sub>2</sub>O<sub>2</sub> resulted in oxidative polymerization of the SNS monomers with concomitant ligation of the DNA modules. The resulting cyclic and linear arrays exhibited chemical and optical properties typical of conducting thiophene-like polymers, with a red-end absorption beyond 1250 nm. AFM images of the cyclic array containing 18 SNS units revealed highly regular 10 nm diameter objects

    Precise Sequence Control in Linear and Cyclic Copolymers of 2,5-Bis(2-thienyl)pyrrole and Aniline by DNA-Programmed Assembly

    No full text
    A series of linear and cyclic, sequence controlled, DNA-conjoined copolymers of aniline (ANi) and 2,5-bis­(2-thienyl)­pyrrole (SNS) were synthesized. In one approach, linear copolymers were prepared from complementary DNA oligomers containing covalently attached SNS and ANi monomers. Hybridization of the oligomers aligns the monomers in the major groove of the DNA. Treatment of the SNS- and ANi-containing duplexes with horseradish peroxidase (HRP) and H<sub>2</sub>O<sub>2</sub> causes rapid and efficient polymerization. In this way, linear copolymers (SNS)<sub>4</sub>(ANi)<sub>6</sub> and (ANi)<sub>2</sub>(SNS)<sub>2</sub>(ANi)<sub>2</sub>(SNS)<sub>2</sub>(ANi)<sub>2</sub> were prepared and analyzed. A second approach to the preparation of linear and cyclic copolymers of ANi and SNS employed a DNA encoded module strategy. In this approach, single-stranded DNA oligomers composed of a central region containing (SNS)<sub>6</sub> or (ANi)<sub>5</sub> covalently attached monomer blocks and flanking 5′- and 3′-single-strand DNA recognition sequences were combined in buffer solution. Self-assembly of these oligomers by Watson–Crick base pairing of the recognition sequences creates linear or cyclic arrays of SNS and ANi monomer blocks. Treatment of these arrays with HRP/H<sub>2</sub>O<sub>2</sub> causes rapid and efficient polymerization to form copolymers having patterns such as cyclic BBA and linear ABA, where B stands for an (SNS)<sub>6</sub> block and A stands for an (ANi)<sub>5</sub> block. These DNA-conjoined copolymers were characterized by melting temperature analysis, circular dichroism spectroscopy, native and denaturing polyacrylamide gel electrophoresis, and UV–visible–near-IR optical spectroscopy. The optical spectra of these copolymers are typical of those of conducting polymers and are uniquely dependent on the specific order of monomers in the copolymer

    Table_1_Trends in economic burden of type 2 diabetes in China: Based on longitudinal claim data.DOCX

    No full text
    ObjectiveDiabetes is a major health issue in China that has a significant economic burden on society. Understanding the economic impact of diabetes can help policymakers make informed decisions about healthcare spending and priorities. This study aims to estimate the economic burden of patients with diabetes in an urban setting in China and to identify the impact of hospitalization and complications on health care costs for people with diabetes.MethodsThe study was conducted in a sample city located in eastern China. All patients diagnosed with diabetes before January 2015 were identified from the official health management information system, and their social demographics and records of their health care uses and costs were extracted from the claim database from 2014 to 2019. Six groups of complications were identified according to ICD-10 codes. The diabetes-related direct medical cost (DM cost) was described for patients in stratified groups. A multiple linear regression model was applied to identify the effect of hospitalization and complications on the DM cost of diabetic patients.ResultsOur research included 44,994 patients with diabetes, the average annual DM costs for diabetic patients increased from 1,292.72 USD in 2014 to 2,092.87 USD in 2019. The costs of diabetes are closely related to hospitalizations and the type and number of complications. The average annual DM cost of patients who were hospitalized was 2.23 times that of those without hospitalization, and it rose as the number of complications increased. Cardiovascular complications and nephropathic complications were the complications that had the greatest impact on patients’ DM costs, increasing by an average of 65 and 54%, respectively.ConclusionThe economic burden of diabetes in urban China has increased significantly. Hospitalization and the type and number of complications have significant impacts on the economic burden of patients with diabetes. Efforts should be made to prevent the development of long-term complications in the population with diabetes.</p

    Total Synthesis of Tricladins A and B and Identification of Their Absolute Configuration

    No full text
    A concise synthesis of both (<i>S</i>)- and (<i>R</i>)-enantiomers of tricladins A and B from l-Boc alanine was achieved. The diastereomeric intermediates were separated by chiral column chromatography, and the absolute configuration of the 2-position was assigned by observed NOE interactions with the known stereogenic center at the 5-position. By comparison of all synthesized final enantiomers with the corresponding natural products, we concluded that the natural tricladins A and B must have the (<i>R</i>)-configuration

    Modular-DNA-Programmed Construction of Permanent Nanoscale Cyclic Assemblies by Reaction of Covalently linked 2,5-<i>bis</i>(2-Thienyl)pyrrole Monomers

    No full text
    DNA modules that contain complementary recognition units and covalently linked 2,5-<i>bis</i>(2-thienyl)­pyrrole (SNS) monomers spontaneously assemble in aqueous buffer solution into cyclic structures. Ligation of the DNA modules is readily accomplished by an oxidative reaction with horseradish peroxidase (HRP)/H<sub>2</sub>O<sub>2</sub>, which results in covalent bond formation between the SNS monomers to form permanent nanoscale assemblies. The flexibility of the cyclic assemblies, and their ability to form SNS-to-SNS bonds, was assessed by varying the number and location of SNS monomers on each DNA module. Efficient ligation is observed when each module contains at least two SNS monomers. Ligation efficiency is diminished when the single stranded regions of the assembly are converted to duplex DNA. The efficient ligation of the DNA structures is attributed to the self-association of the monomers due to their hydrophobicity and is enabled by the flexibility of the single-stranded regions. It was found by systematically controlling the position and number of SNS monomers that these DNA modules are efficiently ligated into cyclic assemblies when each nucleobase module contains at least two SNS monomers. This provides a method for formation of unique covalently linked DNA structures and a process that can readily ligate or cross-link DNA chemically

    Production of Biodiesel by Esterification of Stearic Acid over Aminophosphonic Acid Resin D418

    No full text
    Biodiesel production has become a very intense research field because of its environmental benefits and the growing interest in finding new resources and alternatives for conventional fuels. In the present work, biodiesel production from the esterification of the free fatty acid stearic acid with ethanol over aminophosphonic acid resin D418 was studied. The effects of experimental factors such as the amount of D418, reaction temperature, and molar ratio of ethanol to stearic acid on the conversion ratio were evaluated. Process optimization using response surface methodology (RSM) was performed, and the interactions between the operating variables were elucidated. The optimum values for maximum esterification percentage were obtained by using a Box–Behnken center-united design with a minimum of experimental work. Moreover, the kinetics of the esterification catalyzed by D418 was studied, and the pseudohomogeneous (PH) model was used to simulate the experimental data

    DataSheet_1_Decadal intensified and slantwise Subpolar Front in the Japan/East Sea.zip

    No full text
    The Subpolar Front in the Japan/East Sea (JES) could far-reaching influence the atmospheric processes over the downstream regions. However its variability on decadal timescale remains less understood. In this study, the decadal trends in the intensity and position of the SPF in the JES during the time period 1985−2020 are analyzed by using four categories of satellite observed high-resolution sea surface temperature products. The results show that there is a significant intensification trend of the SPF at a rate of 0.37°C/100km/decade. The SPF is further divided into three regions based on the meridional sea surface temperature gradient (MSSTG): the eastern (135−138°E), central (130−135°E) and western (128−130°E) regions, respectively. These three regions showed different meridional movements with the eastern SPF moving poleward by 0.08°/decade, the central SPF moving equatorward by −0.11°/decade and the western SPF showing no significant displacements. The reverse meridional movements between the central and eastern SPF increased its skewness. The frontogenesis rate equation is employed to identify the mechanisms of these decadal trends. Results show that the geostrophic advection term, especially its zonal component, had a crucial role in the decadal trends of the intensity and position of the central and eastern SPF. The decadal trend of the central SPF was mainly attributed to the zonal geostrophic advection of the MSSTG associated with the enhancement of the Subpolar Front Current (SFC) in the upstream region, whereas the decadal trend in the eastern SPF was mainly driven by the zonal geostrophic shear advection controlled by the shear of the SFC in the downstream region. Before 2002, the eastern SPF moved poleward at a rate of 0.27°/decade, whereas there was no obvious trend after 2002. Further decomposition showed that this shift was caused by meridional Ekman advection of the MSSTG.</p

    Enhanced Photothermocatalytic Synergetic Activity Toward Gaseous Benzene for Mo+C-Codoped Titanate Nanobelts

    No full text
    In the present paper, a simple and facile method is proposed to synthesize Mo+C-codoped titanate (H<sub>2</sub>Ti<sub>5</sub>O<sub>11</sub>·3H<sub>2</sub>O) nanobelts by using hydrothermal method together with sol–gel technique, and various Mo-doped and Mo+C-codoped titanate nanobelts are realized by controlling the precursor’s contents. It is found that the photocatalytic activity of titanate nanobelts toward gaseous benzene will be greatly enhanced by Mo+C-codoping if comparing with that of the pure titanate nanobelts, Mo-doped titanate nanobelts, and C-doped titanate nanobelts, and the optimal Mo doping content is confirmed to be 0.33 wt % for Mo/Ti ratio. The reason lies in the fact that by Mo+C-codoping (Mo/Ti ratio of 0.33 wt %, C/Ti ratio of 0.33 wt %), the band gap of titanate nanobelts will be narrowed and the allowed paths for photoexcitation will be increased with the generation of impurity energy level, which results in an obvious red-shift in their UV–vis absorption spectra and the increased utilization of the solar energy, and thus enhances their photocatalytic activity. On the basis of the above experimental results, the current photocatalytic mechanism is proposed

    Additional file 1: of Plant miRNAs found in human circulating system provide evidences of cross kingdom RNAi

    No full text
    contains supplemental table 1, which summarize count of the reads of plant miRNAs found within each sample. (CSV 2 mb
    • …
    corecore