Sulfate concentrations in pure solutions, drainage waters, and soil saturation extracts were determined potentiometrically using a 70% Pb and 30% Hg amalgam indicator electrode and a saturated calomel reference electrode. Adjusting all samples to pH 4.7 allowed titration to a fixed potential on an automatic titrator. Sulfate concentrations ranging from 0.2 to 10 mmole/liter were determined by this method and compared with concentration determined by a turbidimetric method. Results from the two methods did not differ significantly, but the potentiometric titration method was more precise, sensitive, and rapid.

Electron diffraction techniques have been employed in the study of crystallite orientation within fibrils of cellulose removed from cotton and ramie fibers. It was found that the degree of orientation of crystallites within fibrils representing ten cotton varieties did not deviate appreciably from one another; however, the alpha angle determined for ramie was significantly lower than that determined for the cottons.

Importance values (IV = relative dominance + relative density + relative frequency) were determined for the 12 major canopy species of a mesic north—slope forest in East Tennessee. In addition a fourth term, relative biomass (= above—ground dry weight of a species relative to total stand biomass) was formulated. Comparison of differences between classically determined IV's to IV's containing the relative biomass term indicates that the latter may reflect subtle differences not apparent if biomass is not considered.

The inheritance of Phytophthora root rot resistance was determined in alfalfa (Medicago sativa L.) for five clones from the variety ‘Lahontan’ and six clones from ‘Vernal’ and Vernal-type varieties. A heterozygote-diallel crossing scheme was used as the basis for genetic analysis. Parent clones were selfed, intercrossed, and testcrossed to two susceptible clones. Degree of resistance was determined by type of root-rot lesion. Susceptibility appeared to be conditioned by one tetrasomic gene, Pm, with incomplete dominance. The nulliplex condition produced highly resistant plants. The simplex condition produced a moderate degree of resistance. Duplex, triplex, and quadruplex plants were increasingly more susceptible. Resistance in the Lanhontan and Vernal-type varieties appeared to be controlled by the same gene.

We modified a generalized, plant-alkaloid screening procedure to provide a quick, semiquantitative test for concern tatioii of total basic alkaloids in reed canarygrass (Phalaris arundinacea L.). The test is based upon ocular assessment of discernible differences in turbidity or precipitates produced by silicotungstic acid added to plant extracts. The extracts are prepared by macerating frozen grass in ammoniacal chloroform and then by partitioning into 2 N H₂SO₄. Alkaloid concentrations determined by a summation of readings over five dilutions using the quick test were highly correlated (r = 0.94, P ≤ .01) with concentrations determined by the quantitative laboratory test of Simons and Marten (1971). The quick test is about four times faster than the Simons and Marten test and should enable plant breeders to select low-alkaloid plants or alkaloid-free plants among large numbers of genotypes.

The chromosome morphology of the three native Australian and four exotic Passifiora species in Australia was examined as an adjunct to previous studies (Beal 1969a, 1969b), when chromosome numbers were determined.

<p/>Volatile constituents of white bread were investigated. Different methods were used for isolating and concentrating components to avoid artefacts as far as possible. Especially good was enlarged vapour analysis. Ninety-four components were identified, including hydrocarbons, alcohols, aldehydes, ketones, acids, esters as well as nitrogen, sulphur and miscellaneous compounds. The concentration of the main components in the vapour above white bread was determined by direct vapour analysis. The odour threshold values of these components in aqueous solution were determined, and the odour values calculated as the ratio of concentration to odour threshold value to estimate their contribution to the total odour. The Maillard reaction of the cysteine/cystine-ribose system was investigated in a search for components which can be expected in heat-processed food products, and to find out whether during this reaction compounds possessing bread-like odours were formed. Forty-five components were identified, including thiophenes, thiazoles, thiols, pyrazines, pyrroles, amines, furans, aldehydes, ketones and miscellaneous compounds. Possible pathways for the formation of 2-acylthiazoles and of 3-methyl, and 5-methyl substituted 2-formylthiophenes are proposed.

Volatile constituents of white bread were investigated. Different methods were used for isolating and concentrating components to avoid artefacts as far as possible. Especially good was enlarged vapour analysis. Ninety-four components were identified, including hydrocarbons, alcohols, aldehydes, ketones, acids, esters as well as nitrogen, sulphur and miscellaneous compounds. The concentration of the main components in the vapour above white bread was determined by direct vapour analysis. The odour threshold values of these components in aqueous solution were determined, and the odour values calculated as the ratio of concentration to odour threshold value to estimate their contribution to the total odour. The Maillard reaction of the cysteine/cystine-ribose system was investigated in a search for components which can be expected in heat-processed food products, and to find out whether during this reaction compounds possessing bread-like odours were formed. Forty-five components were identified, including thiophenes, thiazoles, thiols, pyrazines, pyrroles, amines, furans, aldehydes, ketones and miscellaneous compounds. Possible pathways for the formation of 2-acylthiazoles and of 3-methyl, and 5-methyl substituted 2-formylthiophenes are proposed.

The zero point of charge (ZPC) of soils was determined by the crossing point of acid-base potenciometric titration curves in different concentrations of NaCl. Alternatively, the ZPC was found by extrapolating or interpolating the net electric charge of soils, determined by direct adsorption of ions from solution of NaCl, CaCl2 and MgSO4, to the pH of charge zero. | São apresentados os fundamentos e dois métodos de determinação do ponto de carga zero (PCZ) em solos. Por um dos métodos o PCZ foi determinado como sendo o pH do ponto de cruzamento de curvas de titulação dos solos em soluções de NaCl 1; 0.1; 0 01; c 0,001N. Pelo outro método o PCZ foi determinado por extrapolação ou interpolação da carga líquida dos solos, determinada por retenção de íons em soluções de NaCl 0,2N, CaCl2 0,01N e MgSO4 0,01N, ao valor de pH em que a carga líquida era nula.