A systematic mechanistic investigation of CO2 reduction on a Ni-modified Cu(111) surface is performed based on an extensive set of density functional theory (DFT) calculations by focusing on the hydrocarbon CH4 formation pathways. By carefully analyzing reduction pathways on the Ni-modified Cu(111) surface, some important mechanistic information is deduced. The presence of Ni stabilizes all reaction intermediates, and thus reduces the activation barrier for almost all CO2 reduction steps. Most importantly, it can considerably lower than the activation barrier of CO2 hydrogenative dissociation into CO, which is the rate-determining step of CO2 reduction on a pure Cu(111) surface. Thus, the doping of Ni atom is able to activate CO2, leading to enhanced surface activity of CO2 reduction into hydrocarbons. Notably, the activation barriers that are required for CH4 and CH3OH formation are almost all easily overcome through the thermoactive process at ambient temperatures after doping of Ni atom. Thus, a higher CH4 and CH3OH yield may be expected in the presence of the doped Ni atom. Thermodynamic analyses indicate that doping of Ni may reduce the overpotential of CO formation through CO2 hydrogenative dissociation. On this basis, two decriptors may be proposed in order to describe the catalytic activity of Cu-based catalysts for CO2 reduction, and a perfect Cu-based alloy in CO2 reduction should moderately bind CO and form and reduce CO more easily. Simutaneously, CO hydrogenation occurs more easily on the (111) facet of Ni-modified Cu than dimerization, thereby the selectivity of (111) facet of Cu on production CH4 is further confirmed to some degree. The present study reveals a rich reaction chemistry and provides new insights to guide the rational design of Cu-based alloy catalysts for hydrocarbons formation from CO2 reduction.
Iron deficiency derives from a low intake of dietary iron, poor absorption of iron, and high requirements due to growth as well as blood loss. An estimated number of about 50% of all anemia may be attributed to iron deficiency among young children in Cambodia.
Methods
A cross-sectional survey was conducted in rural Cambodia in September 2012. Villages in pre-selected communes were randomly chosen using stunting as a primary indicator of nutritional status. In total, 928 randomly selected households with children aged 3–23 months were included. Hemoglobin, ferritin, soluble transferrin receptor (sTfR), and retinol binding protein (RBP) were assessed from capillary blood samples. In addition, length/height and weight of mothers and children were taken and data on dietary diversity was collected. A child feeding index (CFI) was created. Associations between biomarkers of iron and vitamin A status and nutritional status or food intake were explored.
Results
Anemia prevalence was highest among 6- to 12-months-olds (71%). Ferritin and sTfR inversely correlated and were significantly associated with hemoglobin concentrations. The consumption of animal source foods (ASF) significantly impacts on the interaction between ferritin, sTfR and hemoglobin. Concentrations of RBP were significantly higher in children who had received a vitamin A supplement. The CFI was associated with sTfR and hemoglobin. Lower length and weight were associated with lower ferritin levels and showed an indirect effect on hemoglobin through ferritin.
Conclusion
Nutrition programs targeting children under 2 years of age need to focus on the preparation of complementary foods with high nutrient density to sustainably prevent micronutrient deficiency and generally improve nutritional status. Future assessments of the micronutrient status should include identification of hemoglobinopathies and parasitic infections to better understand all causes of anemia in Cambodian infants and young children.
The inferior recovery of cardiac function after interventional cardiac procedures in elderly patients compared to younger patients suggests that the aged myocardium is more sensitive to stress. We report two studies that demonstrate an age-related deficit in myocardial performance after aerobic and ischemic stress and the capacity of CoQ10 treatment to correct age-specific diminished recovery of function. In Study 1 the functional recovery of young (4 mo) and senescent (35 mo) isolated working rat hearts after aerobic stress produced by rapid electrical pacing was examined. After pacing, the senescent hearts, compared to young, showed reduced recovery of pre-stress work performance. CoQ10 pretreatment (daily intraperitoneal injections of 4 mg/kg CoQ10 for 6 weeks) in senescent hearts improved their recovery to match that of young hearts. Study 2 tested whether the capacity of human atrial trabeculae (obtained during surgery) to recover contractile function, following ischemic stress in vitro (60 min), is decreased with age and whether this decrease can be reversed by CoQ10. Trabeculae from older individuals (> or = 70 yr) showed reduced recovery of developed force after simulated ischemia compared to younger counterparts (< 70 yr). Notably, this age-associated effect was prevented in trabeculae pretreated in vitro (30 min at 24 degrees C) with CoQ10 (400 MicroM). We measured significantly lower CoQ10 content in trabeculae from > or = 70 yr patients. In vitro pretreatment raised trabecular CoQ10 content to similar levels in all groups. We conclude that, compared to younger counterparts, the senescent myocardium of rats and humans has a reduced capacity to tolerate ischemic or aerobic stress and recover pre-stress contractile performance, however, this reduction is attenuated by CoQ10 pretreatment. 相似文献
A non-competitive immunoassay was performed by sodium dodecyl sulfate–capillary gel electrophoresis with UV detection using bovine serum albumin (BSA) and monoclonal anti-BSA. BSA, anti-BSA and their immunocomplexes were well resolved under non-denaturing conditions. A linear calibration curve was obtained and can be used for the quantification of anti-BSA. The limit of detection of anti-BSA was 0.1 μM under the present conditions. Compared with capillary zone electrophoresis, we believed that this method has the potential to be used as a more general format for performing capillary electrophoresis-based immunoassay of medium- and large-sized analytes. 相似文献
