•The erosion of the middle Yangtze in the first 13years after closure of Three Gorges Dam is revealed.•The Three Gorges Dam will affect no further downstream than Chenglingji.•The trend of river bed ...coarsening in the middle Yangtze is predicted.•The possible new hydro-geomorphological equilibrium of the middle Yangtze is forecast.
The environmental impact of the Three Gorges Dam has been a subject of vigorous academic, political and social debate since its inception. This includes the key issue of post-dam river channel erosion, which was predicted by the feasibility study to extend to the river mouth. In this paper we examine the geomorphic response of the channel of the middle Yangtze for 660km downstream of the dam. Using data on channel characteristics, bed material and sediment transport, we show that in the decade following the dam closure, pre-dam seasonal erosion has been replaced by year-round erosion, a pattern most marked at the upstream end of the study area. The sediment carrying capacity of the river channel has been largely reduced below the dam. The locus of bed scour has moved progressively downstream, ceasing as the bed material became too coarse to be transported (e.g. D50: 0.29mm pre-dam coarsened to 20mm below the dam by 2008). About 400km below the dam there is a reduction in channel slope that changes the sediment carrying capacity from 0.25kgm−3 to only about 0.05kgm−3, which is insufficient to move bed sediment. The new long-term hydro-morphological equilibrium that will be established in this section of the middle Yangtze will prevent the further incision downstream initiated by the Three Gorges Dam. The results suggest that the full extent of adverse environmental impact predicted by the pre-dam studies will not eventuate.
Using 2.93 fb −1 of e+e− annihilation data collected at a center-of-mass energy √s = 3.773 GeV with the BESIII detector operating at the BEPCII collider, we search for the semileptonic D0(+) decays ...into a b1(1235) − (0) axial-vector meson for the first time. No significant signal is observed for either charge combination. The upper limits on the product branching fractions are BD0 → b1(1235)−e+νe Bb1(1235)− → ωπ−< 1.12 × 10−4 and BD+ → b1(1235)0e+νe⋅ Bb1(1235)0 → ωπ0< 1.75 × 10−4 at the 90% confidence level.
Using 2.93 fb−1 of e+e− collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay D+ → K+π+π−π0 is ...reported. After removing decays that contain narrow intermediate resonances, including D+ → K+η, D+ → K+ω, and D+ → K+ϕ, the branching fraction of the decay D+ → K+π+π−π0 is measured to be ( 1.13 ± 0.0 8stat ± 0.0 3syst) × 10−3. The ratio of branching fractions of D+ → K+π+π−π0 over D+ → K−π+π+π0 is found to be ( 1.81 ± 0.15 )%, which corresponds to ( 6.28 ± 0.52 ) tan4θC, where θC is the Cabibbo mixing angle. This ratio is significantly larger than the corresponding ratios for other doubly Cabibbo-suppressed decays. The asymmetry of the branching fractions of charge-conjugated decays D± → K±π±π∓π0 is also determined, and no evidence for C P violation is found. In addition, the first evidence for the D+ → K+ω decay, with a statistical significance of 3.3σ, is presented and the branching fraction is measured to be B (D+ → K+ω) = ( 5. 7−2.1 stat+2.5 ± 0.2syst ) × 10−5.
Ni and Co metallic microparticles with submicron size were synthesized with a simple wet chemical reduction method at a relatively low temperature. Then their morphologies and structures were ...characterized by SEM and XRD. Ni metallic microparticles have spherical-shape morphology with fcc crystalline structure, however, Co has a distinct leaf-like morphology with the fcc and hcp mixed phases crystalline structures. For the characterization of their electromagnetic properties, paraffin matrix composites containing different molar ratio Ni and Co mixture powder as fillers were prepared. It was found that both the electromagnetic properties and electromagnetic microwave absorption performances of absorber layer were remarkably influenced by Ni/Co molar ratio. The electromagnetic microwave absorption performances were significantly improved by blending Ni and Co metallic microparticles into paraffin matrix with changing Ni/Co molar ratio, and enhanced mechanism were discussed.
•Ni and Co microparticles were synthesized by a wet chemical reduction method.•EM properties of absorber were remarkably influenced by Ni/Co molar ratio.•EMA performances can be adjusted by artificially changing Co/Ni molar ratio.•Enhanced EMA performances result from multiple EM attenuation mechanisms.
A combined amplitude analysis is performed for the decays B^{0}→Dover ¯^{0}D_{s}^{+}π^{-} and B^{+}→D^{-}D_{s}^{+}π^{+}, which are related by isospin symmetry. The analysis is based on data collected ...by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb^{-1}. Two new resonant states with masses of 2.908±0.011±0.020 GeV and widths of 0.136±0.023±0.013 GeV are observed, which decay to D_{s}^{+}π^{+} and D_{s}^{+}π^{-} respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content csover ¯udover ¯, and the latter state is a neutral tetraquark composed of csover ¯uover ¯d quarks. Both states are found to have spin-parity of 0^{+}, and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet.
To evaluate the role of the erythropoietin (Epo) receptor (R) in erythropoiesis in more primitive stem cells, we assessed the influence of retrovirus-mediated gene transfer of human (h) EpoR ...complementary DNA (cDNA) into murine embryonic stem (ES) cells on erythroid differentiation of these cells. The hEpoR cDNA was efficiently transduced into ES cells, forming hEpoR that stably expressed ES (ES-hEpoR) cells. Expression of hEpoR cDNA was confirmed in ES-hEpoR cells by reverse transcriptase-polymerase chain reaction and Northern blot analysis. Colony assays demonstrated that definitive erythroid and primitive erythroid colonies were significantly increased from ES-hEpoR cells, when compared with mock virus-transduced ES (ES-Neo) cells, during the time course of differentiation induced by withdrawal of leukemia inhibitory factor, in either the presence or the absence of Epo. Multipotential colony-forming units (CFU-Mix) were also increased in ES-hEpoR cells at different stages of differentiation, but no changes were detected for CFU-granulocyte-macrophage colonies (CFU-GM). Time course studies by Northern blot analysis demonstrated elevated levels of expression of beta-H1 and beta-Major globin genes in embryoid bodies derived from ES-hEpoR cells stimulated with Epo, when compared with similar expression from ES-Neo cells. Expression of the GATA-1 gene was enhanced in ES-hEpoR cells, when compared with ES-Neo cells, beginning immediately after initiation of the cultures until 8 days of differentiation. These data indicate that primitive and definitive erythropoiesis in differentiating embryoid bodies can be enhanced by retrovirus-mediated gene transfer of an hEpoR gene.
Biol Blood Marrow Transplant 2000;6(4):395-407.
To investigate the prevalence and risk factors for chronic obstructive pulmonary disease (COPD) in a rural area in western China with severe air pollution.
10% of local residents aged 40 years and ...above were included using a convenience sampling method. This was a cross-sectional study. A self-designed questionnaire was used to collect participants' demographic data. The screening program was comprised of two steps: First, a portable electronic spirometer was used for COPD screening. Those participants with FEV
/FVC ratio <0.7 were then referred to a confirmatory pulmonary function (PF) test. COPD was confirmed according to the 2020 Global Initiative for Chronic Obstructive Lung Disease criteria.
A total of 4577 participants aged 40 years old or above were included in the final analysis. Examination with a mobile spirometer identified 1159 individuals for confirmatory testing; after that, of the 1159 individuals, 889 were diagnosed with COPD by the confirmatory PF test. The prevalence of COPD among the target group was 19.4%. Older age, male sex (odds ratio OR = 1.537, 95% confidence interval CI 1.246-1.894), smoking history (OR = 1.338, 95% CI 1.069-1.675), family history of respiratory disease (OR = 1.625, 95% CI 1.350-1.957), education level (OR = 0.735, 95% CI 0.617-0.876), overweight (OR = 0.614, 95% CI 0.517-0.730) and obesity (OR = 0.572, 95% CI 0.449-0.721) were identified as independent factors associated with COPD. The screening program helped earlier detection of COPD in 719 participants.
COPD was highly prevalent in the rural area studied. Rural residents who were older, current or ever-smokers, male and those who had a lower education level were more vulnerable to developing COPD. The COPD screening program may be helpful for earlier disease detection in rural health-care settings.
Cefquinome (CEF) is widely used for veterinary clinical applications because of its broad spectrum and high efficiency. However, frequent administrations are required due to its short elimination ...half‐life. In this study, cefquinome sulfate gelatin microspheres (CEF‐GMS) were prepared as a sustained‐release formulation using emulsion chemical cross‐linking technique. Physical properties, stability, sustained‐release property in vitro, and pharmacokinetics in pigs were assessed. The morphology of CEF‐GMS showed a good sphericity with porous structure on the surface, and the mean diameter was 8.80 ± 0.78 μm, with 90.60 ± 3.98% of the total in the range of 5–20 μm. There were no significant changes of all estimated indexes in the stability tests. In vitro drug release study showed that the release of CEF from CEF‐GMS was much slower than that from crude CEF in a release medium. Pharmacokinetic characteristics were evaluated following intramuscular administration of CEF‐GMS or Cefquinome sulfate injection (CEF‐Inj) in pigs at a dosage of 4 mg CEF/kg body weight. The plasma drug concentration–time data of CEF‐GMS and CEF‐Inj were both best fitted by two‐compartment models with first‐order absorption, and the elimination half‐life of CEF‐GMS was almost 10 times that of CEF‐Inj. Overall, CEF‐GMS might be used as a sustained‐release formulation of CEF for veterinary clinical applications.
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