Reducing the influence of perfectionism and statistics anxiety on college student performance in statistics courses.

The influence of perfectionism and statistics anxiety on academic performance (AP) in statistics courses was investigated using a multidimensional perfectionism scale and a statistics anxiety rating scale. For perfectionism, the factor of personal standards (PS) had a significant direct positive effect on AP, while the factor of parental expectations (PE) was significantly negatively correlated with AP. Other factors (concern over mistakes, organization, and doubts about actions) did not significantly influence AP. For statistics anxiety, the two factors (test and class anxiety and computation self-concept) significantly impaired AP. These results indicated a need for innovation in classroom instruction and the reform of statistics course content and presentation to reduce statistics anxiety and improve PS. There is also a need to ensure that students better internalize PE and to revise instructional design techniques to enhance students' independent learning ability.

Study on the Design, Preparation, and Performance Evaluation of Heat-Resistant Interlayer-Polyimide-Resin-Based Neutron-Shielding Materials.

Polymers have an excellent effect in terms of moderating fast neutrons with rich hydrogen and carbon, which plays an indispensable role in shielding devices. As the shielding of neutrons is typically accompanied by the generation of γ-rays, shielding materials are developed from monomers to multi-component composites, multi-layer structures, and even complex structures. In this paper, based on the typical multilayer structure, the integrated design of the shield component structure and the preparation and performance evaluation of the materials is carried out based on the design sample of the heat-resistant lightweight polymer-based interlayer. Through calculation, the component structure of the polymer-based materials and the three-layer thickness of the shield are obtained. The mass fraction of boron carbide accounts for 11% of the polymer-based material. Since the polymer-based material is the weak link of heat resistance of the multilayer shield, in terms of material selection and modification, the B4C/TiO2/polyimide molded plate was prepared by the hot-pressing method, and characterization analysis was conducted for its structure and properties. The results show that the ball milling method can mix the materials well and realize the uniform dispersion of B4C and TiO2 in the polyimide matrices. Boron carbide particles are evenly distributed in the material. Except for Ti, the other elemental content of the selected areas for mapping is in good agreement with the theoretical values of the elemental content of the system. The prepared B4C/TiO2/polyimide molded plate presents excellent thermal properties, and its glass transition temperature and initial thermal decomposition temperature are as high as 363.6 °C and 572.8 °C, respectively. In addition, the molded plate has good toughness performs well in compression resistance, shock resistance, and thermal aging resistance, which allows it to be used for a long time under 300 °C. Finally, the prepared materials are tested experimentally on an americium beryllium neutron source. The experimental results match the simulation results well.

Effects of phase separation on dewaterability promotion and heavy metal removal of sewage sludge during bioleaching.

Bioleaching is of increasing interest because of its high efficiency in improving sludge dewaterability and removing heavy metals from sewage sludge. However, in traditional single-phase bioleaching, a high-efficiency level cannot be maintained continuously, wherein the microbial synergistic effect is disrupted at a low pH environment. Therefore, in this study, a series of multi-compartment-baffled flow trials were performed to assess the effects of phase separation on sludge bioleaching by comparing a two-phase trial with two single-phase trials. Energy substrate and part of the bioleached sludge were introduced separately into two compartments to form two phases, namely selection phase and bioleaching phase. The results show that phase separation apparently shortened the start-up duration of sludge bioleaching from 7 days in a single-phase bioleaching to 4 days in two-phase bioleaching. The dewaterability of bioleached sludge was also enhanced by phase separation with relative decreases of 25.0-33.3% for specific resistance to filtration and 14.2% for capillary suction time, which was attributed to lower pH values, zeta potential closer to zero, and less dissolved organic matter in bioleached sludge after two-phase bioleaching. Phase separation generally increased the removal ratios of heavy metals during sludge bioleaching by -0.79 to 2.60%, 11.06 to 15.04%, 4.45 to 11.03%, 17.98 to 23.46%, 7.20 to 9.28%, -9.22 to -2.46%, and -6.72 to -10.68% for As, Cd, Cr, Cu, Ni, Pb, and Zn, respectively. Phase separation also enriched the Acidithiobacillus spp. and reduced the inactivation of acid-tolerant fungi, which can be conducive to better synergistic effect, and therefore maintain long-term stable state in the bioleaching phase of the two-phase bioleaching process.

Ethylenediurea offers moderate protection against ozone-induced rice yield loss under high ozone pollution.

Tropospheric ozone (O3) is the main phytotoxic air pollutant threatening food security, while ethylenediurea (EDU) can effectively mitigate O3-induced crop yield loss. EDU's mode of action, however, remains unclear, and the underlying physiological mechanisms of mitigating O3-induced crop yield loss are poorly understood. We cultivated hybrid rice seedlings under two O3 treatments (NF, nonfiltered ambient air; and NF60, ambient air plus 60 ppb O3) and sprayed foliage with 0 or 450 ppm EDU every ten days and determine photosynthesis-related traits, biomass indicators, and yield components. We found that EDU significantly increased the leaf nitrogen (N) allocation to photosynthesis (NP) and the grain N accumulation, while the grain N accumulation was positively correlated with NP and root biomass. EDU significantly increased the rice yield mainly by increasing the individual grain weight rather than the number of panicles and grains. While EDU protected from yield loss, the degree of protection was only 31% under NF60 treatment, thus EDU was unable to offer complete protection under high O3 pollution. These results will be conducive to a better understanding of the EDU protection mechanism and better application of EDU under high O3 pollution in the future.

Study on a High-Boron-Content Stainless Steel Composite for Nuclear Radiation.

In this research, a high-boron-content composite material with both neutron and γ rays shielding properties was developed by an optimized design and manufacture. It consists of 304 stainless steel as the matrix and spherical boron carbide (B4C) particles as the functional particles. The content of B4C is 24.68 wt%, and the particles' radius is 1.53 mm. The density of the newly designed material is 5.17 g·cm-3, about 68.02% of that of traditional borated stainless steel containing 1.7 wt% boron, while its neutrons shielding performance is much better. Firstly, focusing on shielding properties and material density, the content and the size of B4C were optimized by the Genetic Algorithm (GA) program combined with the MCNP program. Then, some samples of the material were manufactured by the infiltration casting technique according to the optimized results. The actual density of the samples was 5.21 g cm-3. In addition, the neutron and γ rays shielding performance of the samples and borated stainless steel containing 1.7 wt% boron was tested by using an 241Am-Be neutron source and 60Co and 137Cs γ rays sources, respectively, and the results were compared. It can be concluded that the new designed material could be used as a material for nuclear power plants or spent-fuel storage and transportation containers with high requirements for mobility.

Ethylenediurea (EDU) protects inbred but not hybrid cultivars of rice from yield losses due to surface ozone.

The rising concentration of ground-level ozone (O3) reduces crop yield via increased oxidative stress. Application of ethylenediurea (EDU) protects plants from O3 and could thereby serve as a means to estimate the crop yield losses due to ambient O3 (AO3). However, no study but a few exceptions has ever compared the yield loss estimates from EDU application with those from O3 elevation experiments. Here, we estimated yield loss to AO3 in rice cultivars across the 3 types, indica, japonica, and hybrid, by an EDU application in the field, and compared the yield losses with those estimated with dose-response relationships based on O3 elevation experiments. Relative yield loss (RYL) in the EDU application was estimated at 16% across the rice types on an assumption of a 100% efficiency for protection of crop yield by EDU. This estimate of RYL was close to the 15% RYL estimated from the O3 elevation experiments when a common sensitivity to O3 is assumed across the cultivars. The rice yield loss due to AO3 was thus consistent between the two approaches supporting the idea of EDU application for the yield loss estimation. When only hybrids are focused, however, the RYL from EDU application (16%) was much lower than the 34% RYL from the O3 elevation experiments, which indicates only a 37% yield protection by EDU in the hybrid rice. The incomplete protection by EDU and its genetic variability indicates the need to quantify the efficiency of protection from AO3-induced yield loss as estimated with O3 manipulating experiments.

Novel ozone flux metrics incorporating the detoxification process in the apoplast: An application to Chinese winter wheat.

A modified Ball-Berry-Leuning model of stomatal conductance was applied to data from fully open-air ozone (O3)-enrichment experiments with winter wheat (Triticum aestivum L.). The O3 fluxes reaching both surface of cell wall (Fcw) and plasmalemma (Fpl) were estimated considering apoplastic ascorbate, a major scavenger of O3. The difference (D) between Fcw and Fpl was defined as detoxification capacity of O3 by reaction with ascorbate in the leaf apoplast (ASCapo). The accumulated stomatal O3 flux above D nmol O3 m-2 s-1 (AFstD) and the accumulated Fpl (AFpl) were calculated over the optimal integration period covering the whole reproductive development of wheat, and used to derive O3AFstD yield-response relationships in comparison with PODY (phytotoxic O3 dose above a threshold of Y nmol m-2 s-1) and AOT40 (accumulated O3 dose over a threshold of 40 ppb). There was a good agreement between the observed and modeled values of ASCapo and stomatal conductance. AFstD and AFpl performed better than PODY and AOT40 in terms of R2 and intercept. However, the AFstD metric was more suitable for assessing grain yield loss due to lower sensitivity of the regression slope to variations in the input parameters, compared with AFpl. The average critical level (CL) of four cultivars for 5% grain-yield reduction was 1.53 mmol m-2 using POD6 and 2.81 mmol m-2 using AFstD, with the latter being well above the POD6-derived value for European cultivars (1.3 mmol m-2). The minimum hourly averaged O3 concentration contributed to CLs was below 20 ppb according to AFstD, a value that is lower than that suggested by POD6 (≈27 ppb). O3 flux-response relationships and CLs on the basis of quantified detoxification capacity shall facilitate the understanding of the different degrees of susceptibility to O3 among species or cultivars, and improve the assessments of O3 impacts on plants.

Structure elucidation and NMR assignments of an alkaloid from Ixeris chinensis Nakai.

A new alkaloid, 2-amino-1,6-dihydro-pyridine-5-carbaldehyde (1), together with four known compounds, namely 4-hydroxybenzaldehyde (2), 4-hydroxyacetophenone (3), acetophenone-4-O-ß-d-glucoside (4), 2-hydroxyl-6-methoxyacetophenone-4-O-ß-d-glucoside (5), were isolated from the CHCl3 extract from Ixeris chinensis Nakai. The structures of 1 was elucidated by spectroscopic methods, including UV, IR, HR-ESI-MS and extensive 1D and 2D NMR techniques.

Two New Compounds from Artemisia sacrorum.

Two new compounds, named as sacric acid A (1) and sacric acid B (2), were isolated from the EtOAc extract of Artemisia sacrorum Ledeb. This is the first report on the structure elucidation of these compounds based on UV, IR, and extensive ID and 2D NMR spectroscopic, and ESI-MS techniques.

High-speed countercurrent chromatography isolation of flavans from Ixeris chinensis and their identification by NMR spectroscopy.

High-speed countercurrent chromatography, combined with macroporous resin chromatography were applied to the separation and purification of flavans from Ixeris chinensis. Four flavans, namely, 5-methoxy-7,4'-dihydroxyflavan-3-ol (1), 5,7-dimethoxy-4'-hydroxyflavan-3-ol (2), 5,7-dimethoxy-4'-hydroxyflavan (3), and 5,7-dimethoxy-8-methyl-4'-hydroxyflavan (4), were obtained from I. chinensis for the first time. Their chemical structural identification was carried out by spectroscopic methods, including 1D and 2D NMR spectroscopy. Amounts of 13.2 mg of compound 1, 6.4 mg of compound 2, 5.8 mg of compound 3, and 14.5 mg of compound 4 were separated from 120 mg 75% ethanol fraction. The purities of 1-4 were 99.1, 99.2, 97.3, and 98.6 %, respectively.

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2) = 0.85 & T2: R(2) = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2) of cumulative ozone uptake. At the regional level, dry matter loss in winter wheat would reach 50% under elevated ozone concentrations and reduced solar irradiance as determined in T1, and 30% under conditions as determined in T2. Results from this study suggest that a combination of elevated ozone concentrations and reduced solar irradiance could result in substantial dry matter loss in the Chinese wheat-growing regions.

Analgesic effects and structural elucidation of two new flavone C-glycosides from Artemisa sacrorum.

The present study was designed to isolate and characterize the analgesic compounds of Artemisa sacrorum Ledeb. The EtOAc crude extracts from the aerial parts of Artemisa sacrorum Ledeb were separated by chromatography and the structures of new compounds were elucidated based on spectral analyses. Analgesic activities of the isolated compounds were assessed in rats with hot plate test and paw pressure assay. Two new flavone C-glycosides, named as Sacroroside A and B (Compounds 1 and 2) were isolated from the EtOAc crude extract of the aerial parts ofArtemisa sacrorum Ledeb. They showed significant analgesic effects. In conclusion, Compounds 1 and 2 are new natural products, which show significant analgesic effects in a dose-dependent manner.

[Study on Chemical Constituents of Panzeria alaschanica].

OBJECTIVE: To study the chemical constituents of the ethyl acetate extract from Panzeria alaschanica. METHODS: The chemical constituents of ethyl acetate extract from Panzeria alaschanica were isolated and purified by silica gel. Their structures were i- dentified by means of spectra. RESULTS: Nine compounds were obtained and identified as 7-Methoxy coumarin (1), Isorhamnetin (2), Caf- feic acid (3), 5-Hydroxy-7,3',4'-trimethoxyflavone (4), 5-Hydroxy-7,4'-dimethoxyflavone (5),Kaempferol (6), Isorhamnetin-3-O-ß-D- glucoside (7) Kaempferol-3-O-ß-D-glucoside (8), and Isorhamnetin-7-O-ß-D-glucuronyl-(1-->6)-O-α-L-rhamnoside (9). CONCLUSION: Compounds 1-4,6,7 and 9 are isolated from this plant for the first time.

A biflavonoid glycoside from Lomatogonium carinthiacum (Wulf) Reichb.

A biflavonoid glycoside with a new carbon skeleton, named carinoside A, was isolated from the n-BuOH crude extract of the whole plant of Lomatogonium carinthiacum (Wulf) Reichb. The structure of the new compound was elucidated by using spectroscopic methods, including UV, IR, HR-ESI-MS and extensive 1D and 2D NMR techniques.

A new sesquiterpene from Ixeris chinensis.

The petroleum ether (PE) extract from Ixeris chinensis was submitted to chromatographic separation. A new sesquiterpene, namely 14-noreudesma-3-hydroxy-3-en-2,9-dione, was isolated from the PE extract. The structures of the sesquiterpene was elucidated by using spectroscopic methods, including UV, IR, HR-ESI-MS and extensive 1D and 2D NMR techniques.

[Nitrous oxide flux at the water-air interface of the rivers in Nanjing during summer].

Employing floating static chamber-chromatography method, the N2O diurnal fluxes at the water-air interface of four rivers (Tuanjie River, Jinchuan River, Inner and Outer Qinhuai River) and Jinniu Lake were monitored in Nanjing during summer. The results show that four rivers act as the sources of N2O emission, but Jinniu Lake is characterized by the absorption of N2O. The highest N2O flux from Inner Qinhuai presented at 20:00 because of the changing of hydrodynamic conditions. Both Jinchuan and Tuanjie rivers' minimum N2O fluxes were detected when the content of dissolved oxygen was extremely low. The tendency of N2O from Outer Qinhuai showed a double-peak because of its daytime nitrification and nocturnal denitrification. The flux of N2O from Jinniu Lake had been noted as being generally higher at night than that during light hours due to the effect of wind. For natural rivers, the proper sampling period is from 08:00 to 12:00, but for the river subjected to interference, the sampling period is different.

[An improved method and its application for agricultural drought monitoring based on remote sensing].

From the viewpoint of land surface evapotranspiration, and by using the semi-empirical evapotranspiration model based on the Priestley-Taylor equation and the land surface temperature-vegetation index (LST-VI) triangle algorithm, the current monitoring technology of agricultural drought based on remote sensing was improved, and a simplified Evapotranspiration Stress Index (SESI) was derived. With the application of the MODIS land products from March to November in 2008 and 2009, the triangle algorithm modeling with three different schemes was constructed to calculate the SESI to monitor the agricultural drought in the plain areas of Beijing, Tianjin, and Hebei, in comparison with the Temperature Vegetation Dryness Index (TVDI). The results showed that SESI could effectively simplify the remote sensing drought monitoring method, and there was a good agreement between SESI and surface soil (10 and 20 cm depth) moisture content. Moreover, the performance of SESI was better in spring and autumn than in summer, and the SESI during different periods was more comparable than TVDI. It was feasible to apply the SESI to the continuous monitoring of a large area of agricultural drought.

An analysis of influential factors on outdoor thermal comfort in summer.

A variety of research has linked high temperature to outdoor thermal comfort in summer, but it remains unclear how outdoor meteorological environments influence people's thermal sensation in subtropical monsoon climate areas, especially in China. In order to explain the process, and to better understand the related influential factors, we conducted an extensive survey of thermally comfortable conditions in open outdoor spaces. The goal of this study was to gain an insight into the subjects' perspectives on weather variables and comfort levels, and determine the factors responsible for the varying human thermal comfort response in summer. These perceptions were then compared to actual ambient conditions. The database consists of surveys rated by 205 students trained from 6:00 am to 8:00 pm outdoors from 21 to 25 August 2009, at Nanjing University of Information Science & Technology (NUIST), Nanjing, China. The multiple regression approach and simple factor analysis of variance were used to investigate the relationships between thermal comfort and meteorological environment, taking into consideration individual mood, gender, level of regular exercise, and previous environmental experiences. It was found that males and females have similar perceptions of maximum temperature; in the most comfortable environment, mood appears to have a significant influence on thermal comfort, but the influence of mood diminishes as the meteorological environment becomes increasingly uncomfortable. In addition, the study confirms the strong relationship between thermal comfort and microclimatic conditions, including solar radiation, atmospheric pressure, maximum temperature, wind speed and relative humidity, ranked by importance. There are also strong effects of illness, clothing and exercise, all of which influence thermal comfort. We also find that their former place of residence influences people's thermal comfort substantially by setting expectations. Finally, some relationships between thermal perception and amount of exercise, thermal experience, mood, clothing, illness and microclimate, etc., are established. Our findings also shed light on how to resist or adapt to outdoor hyperthermic conditions during summer in subtropical monsoon climate areas.

[Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.