Field studies with boron on muscadine grapes

Abstract

A 2‐year study failed to show a significant yield response from soil applications of boron to eight‐year‐old muscadine grape vines; however, a definite trend toward yield response was evident from linear regression models. No difference in B levels of tissue occurred the initial year but in the second year, the tissue from the highest B rate was significantly higher than other treatments. Boron content of the soil correlated well with B treatment levels (r = .88). Fruit soluble solids were not related to B treatments.     

Arsenic-contaminated soils phytotoxicity studies with sunflower and sorghum

Background, Aim and Scope  Environmental pollution caused by arsenic (As) is a major ecological problem. There has been intense worldwide effort to find As-hyperaccumulating plants that can be used in phytoremediation—the green-plant-assisted removal of chemical pollutants from soils. For phytoremediation, it is natural to prefer cultivated rather than wild plants, because their agriculture is well known. This study was conducted to evaluate the tolerance of common sunflower(Helianthus annuus L.) and sugar sorghum(Sorghum saccharatum Pers.) for soil-As contents of 10–100 mg As kg^-1 soil, with sodium arsenite as a model contaminant. Methods  Plants were grown in a growth chamber for 30 days. Microfield experiments were conducted on experimental plots. To study the phytoremediation effect of the auxins indole-3-acetic acid (IAA) and 2,4-dichlorophenoxyacetic acid (2,4-D), we treated 1- and 3-day-old plant seedlings with water solutions of the auxins (concentrations 10^-5, 10^-7, and 10^-9 g l^-1). The soil and plant-biomass samples were analyzed for total As by using the color reaction of ammonium molybdate with As. Results and Discussion  Phytotoxicity studies showed that 100 mg As kg^-1 soil poisoned sunflower and sorghum growth by 50%. There was a linear correlation between soil-As content and As accumulation in the plants. Laboratory experiments showed that the soil-As content was reduced two- to threefold after sunflower had been grown with 10–100 mg As kg^-1 soil for 30 days. Treatment of sunflower and sorghum seedlings with IAA and 2,4-D at a concentration of 10^-5 g l^-1 in microfield experiments enhanced the phytoremediation two- to fivefold as compared with untreated control plants. The best results were obtained with 3-day-old seedlings. Conclusion, Recommendation and Outlook  (a) Sunflower and sorghum are good candidates to remediate As-polluted soils. (b) Phytoremediation can be improved with IAA or 2,4-D. (c) Mixed cropping of sorghum and sunflower may be another way of improving phytoremediation.     

Outliers in collaborative studies: coping with uncertainty

An overview is given of the options available in detecting and dealing with outliers in collaborative studies. The fundamental points of agreement and disagreement are highlighted. The common sense approach of just looking at the data is emphasized. The importance is stressed of making a harmonized choice of outlier treatments, even though such a choice may not be optimal for all circumstances.     

Comparison of carcinogenicity studies with aldrin and dieldrin.

Laboratory testing of animals is the principal method used to identify chemical carcinogens. However conflicting results are often obtained. This is emphasized in a cross-comparison of 6 aldrin-dieldrin studies; 3 were positive for tumor induction and 3 were negative. Four components of the assays are examined: husbandry, compound administration, observation, and interpretation of results.     

Molecular spectroscopic studies of farrerol interaction with calf thymus DNA

The interaction between farrerol and calf thymus DNA in a pH 7.4 Tris-HCl buffer was investigated with the use of neutral red (NR) dye as a spectral probe by UV-vis absorption, fluorescence, and circular dichroism (CD) spectroscopy, as well as viscosity measurements and DNA melting techniques. It was found that farrerol molecules could intercalate into the base pairs of DNA as evidenced by decreases in iodide quenching effect and single-stranded DNA (ssDNA) quenching effect, induced CD spectral changes, and significant increases in relative viscosity and denaturation temperature of DNA. Furthermore, the spectral data matrix of the competitive reaction between farrerol and NR with DNA was resolved with an alternative least-squares (ALS) algorithm, and the concentration profiles in the reaction and the corresponding pure spectra for three species (farrerol, NR, and DNA-NR complex) were obtained. This ALS analysis demonstrated the intercalation of farrerol to the DNA by substituting for NR in the DNA-NR complex. Moreover, the thermodynamic parameters enthalpy change (ΔH°) and entropy change (ΔS°) were calculated to be -16.49 ± 0.51 kJ mol(-1) and 32.47 ± 1.02 J mol(-1) K(-1) via the van't Hoff equation, which suggested that the binding of farrerol to DNA was driven mainly by hydrophobic interactions and hydrogen bonds.     

Reactions of p-coumaric acid with nitrite: product isolation and mechanism studies

p-Coumaric acid (1) is an abundant plant phenolic acid, a dietary chemoprotectant, and an antioxidant. The chemoprotective properties of 1 were demonstrated in vitro by its reaction with NaNO(2) in H(2)O over a range of pH values. The reaction pathway of 1 with nitrite is dependent on pH. 4-Hydroxybenzaldehyde (3, 16%), 1',4-dihydroxybenzeneacetaldehyde oxime (5, 59%), and 4-hydroxy-1'-oxo-benzeneacetaldehyde aldoxime (7, 26%) and 7-hydroxy-1,2(4H)-benzoxazin-4-one (11, 6%) were each formed at pH 2, whereas 4-(2-oxido-1,2,5-oxadiazol-3-yl)phenol (13) was formed at pH 3 (6%) and pH 7 and 10 (both 1%). Products were isolated and characterized by NMR and MS spectral analyses. Formation of benzoxazinone (11) requires the 4-phenolic functional group and the conjugated propenoic acid side chain of p-coumaric acid. The mechanism for nitrosation at pH 2 was examined by reacting 1 in H(2)(18)O/NaNO(2).     

泥沙来源“指纹”示踪技术研究综述

泥沙来源"指纹"示踪技术是综合研究流域土壤侵蚀和泥沙输移的新方法。泥沙来源"指纹"示踪技术基于流域侵蚀产沙过程划分潜在物源类型,根据物源特性筛选具有诊断能力的"指纹"性质,通过定量转换模型建立流域出口泥沙与内部潜在物源间的"指纹"联系,定量描述各潜在物源对流域出口产沙的相对贡献;结合悬移质或沉积泥沙通量监测,定量分析各潜在物源对流域产沙的绝对贡献量及流域侵蚀产沙时、空变化特征。通过综述泥沙来源"指纹"示踪技术的理论基础及实施框架,流域尺度潜在物源类型,泥沙"指纹"因子类别、分布特点及诊断能力,泥沙来源复合"指纹"示踪技术的研究进展,指出泥沙来源"指纹"示踪技术的局限性,并对泥沙来源"指纹"示踪技术进行展望。     

Binding studies of oxovanadium(V) with ovalbumins (OA)

The effect of protein oxovanadium(V) ion concentration and pH on the ratio of diffusion current (id/id₀) was studied in vanadium(V) ovalbumin-S and denatured ovalbumin systems. In both the cases marked decrease in diffusion current was observed at the respective pH values, indicating that binding takes place with cationic groups of the proteins. The binding sites (n) were found to be pH dependent. The uniformity of logK and ΔG ⁰ value at all pH values indicated the involvement of same sites in interaction. Furthermore, the linear scatchard plots in both the systems supported the involvement of single class of independent sites in oxovanadium(V) anion interaction. The difference in binding sites (n) has been attributed to the folded structure of ovalbumin-S while unfolded one of denatured ovalbumin.     

A unified approach for estimating population size in capture-recapture studies with arbitrary removals

A unified approach is suggested to estimate the population size for a closed population in discrete time. Individuals can be removed after capture at any time during the experiment. The usual recapture and removal experimentsare shown to be particular cases of the general formulation. The capture probability is assumed to have a logistic function that depends on individual covariates and can be time dependent. The unified approach involves a two-step procedure. A conditional likelihood function is used to estimate the covariates coefficients and a Horvitz-Thompson type estimator to estimate the population size. The asymptotic and small-sample properties of the resulting estimators are in vestigated. A real example is given.