年龄战争

在《从婴儿车到轮椅》一文中，我们探讨了所谓17种不同的生活方式。不仅越来越多的划分类别令人惊讶,年龄整体压缩的情况也同样如此。     

SULFORAPHANE POTENTIAL AND VITAMIN C CONCENTRATION IN DEVELOPING HEADS AND LEAVES OF BROCCOLI (BRASSICA OLERACEA VAR. ITALICA)

Abstract The accumulation of sulforaphane and vitamin C was studied in developing heads and leaves of broccoli. Sampling was conducted from early head initiation through commercial maturity. Whole plant fresh mass, plant height and also head mass, diameter and height were recorded from three composite samples. Gas chromatography and redox titration were used to analyze for sulforaphane potential (SP) ² and vitamin C (VC) concentration, respectively. Results were reported on a dry mass basis (dmb). Sulforaphane potential in heads increased through maturity from 3.96 to 30.11 μmol.g^-1. In leaves, SP peaked 82 days after sowing and decreased until sampling ended with values ranging from 0.13     

Effect of Handling and Packaging on the Quality of Frozen Whitefish

Individually frozen, scaled whitefish (Coregonus clupeaformis) rapidly developed oxidative off-flavors when stored without packaging at ?12°C, but both vacuum-packaging in barrier films and ice-glazing significantly suppressed the development of oxidized flavors through 24 wk of storage. Removal of scales prior to freezing significantly enhanced the development of oxidized flavors over unscaled whitefish when both were held unprotected at ?12°C. Loose-packaging of individual, well-washed whitefish in closed polyethylene pouches significantly improved oxidative stability compared to those stored unprotected. However, vacuum, barrier-film packaging gave significantly better protection than polyethylene at both ?12°C and ?25°C through 24 wk and 72 wk, respectively.     

Ion-Probe Measurement of Oxygen Self-Diffusion in Single-Crystal Al2O3

Anion self-diffusion coefficients normal to (1102) were obtained for single-crystal Al₂O₃ in a 1.3 × 10 ³ N/m² (10⁻⁵ torr) vacuum at 1585° to 1840°C. Tracer was supplied from an initial 650 to 1300 A Al₂¹⁸O₃ layer produced by the oxidation of vapor-deposited Al metal films in an ¹⁸O₂ atmosphere at 520°C. Concentration gradients extended over depths of 3000 to 5000 A and were measured by mass spectrometry of material sputtered from the samples with a beam of Ar⁺ ions. Crystals which had not been preannealed to remove surface damage displayed enhanced diffusion. Diffusion coefficients from preannealed crystals may be described by D₀ =6.4×10⁵cm²/s, with an activation energy of 188 ± 7 kcal/mol. The diffusion is interpreted as an extrinsic vacancy mechanism.     

HE HYDROLOGY OF OVERLAND FLOW IN WETLANDS

An experimental study on mixing, degree of suspension and power consumption in solid-liquid suspensions was done. A system similar to those found in anaerobic fermentation processes of animal manures was used, and an existing mixing equipment was adapted for the study. Power consumption and degree of suspension for both mechanical mixing and mixing by gas was determined. The influence of variables such as geometry, solids concentration, stirrer velocity, and gas velocity was studied, discussed, and compared to data from the literature. Best results were obtained for gas mixing, the power consumption being about one fourth of that required by mechanical agitation. Finally, extended correlations relating Power and Reynolds numbers for mechanical mixing and mixing by gas are proposed.     

WALL JET DEVELOPMENT IN A TURBULENT RECIRCULATING CAVITY FLOW

A turbulent wall jet within a confining recirculating cavity was examined using flow visualization, particle image velocimetry (PIV), and laser Doppler velocimetry (LDV). The PIV technique was used macroscopically for flow visualization as well as at a much finer resolution to determine detailed velocities within the developing wall jet. Comparison data collected using laser Doppler velocimetry (LDV) was used for validation purposes. The wall jet was well characterized using conventional unbounded wall jet parameters. Wall jet velocity profiles collapsed onto a single profile with the application of the appropriate parameters, indicating some degree of similarity after the initial jet region and up to the mid wall distance. Distances past this region were characterized by a rapid decay in the jet caused by the adverse pressure gradient created by the bounding wall. It was found that the wall jet growth rate within the recirculating cavity was greater than that of an unbounded wall jet in a stagnant fluid. This phenomenon is attributed to the recirculating flow, confining boundaries, and the initial jet exit velocity conditions.     

Gas Chromatographic Determination of Butylated Hydroxyanisole, Butylated Hydroxytoluene and Tertiarybutyl Hydroquinone in Soybean Oil

Oils containing different levels of the most common phenolic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tertiarybutyl hydroquinone (TBHQ) from 0–200 ppm were analyzed by a new gas chromatographic method. The antioxidants in oils were isolated by nitrogen gas purging, collected on Tenax GC coated with polymetaphenoxylene, and then separated and quantitated by gas chromatography. This method requires neither extraction of antioxidants from oil nor derivatization of antioxidants. The correlation coefficients (r) between gas chromatographic peak heights or peak area and their concentrations in oils were 0.99 for BHA, BHT, and TBHQ. This simple gas chromatographic method can determine as little as 10 ppm pf BHA, BHT, or TBHQ in oils in an hour.     

Effects of Citric Acid and Iron Levels on the Flavor Quality of Oil

A factorial design of four levels of added iron (0, 0.1,1 and 5 ppm) and five levels of citric acid (CA) (0, 10, 50, 100, 150 ppm) was used to study interaction effects of citric acid and added iron on flavor quality of oils containing 0.1 ppm iron. Flavor qualities were evaluated by measurement of dissolved free oxygen disappearance and flavor compound formation in oils. When oils contained 0 or 0.1 ppm added iron, the five levels of CA did not affect flavor quality. But, when the oils contained 1 ppm of added iron, increasing the content of CA, rate of oxygen disappearance decreased and smaller concentrations of flavor compounds formed. Results also showed that as the iron content was increased, the rate of dissolved oxygen disappearance increased and the larger concentrations of flavor compounds formed in the oil.