Ionization of liquids by radiation: measurement by a clearing field

A method has been developed for determining the yield of free ions formed by irradiation of a liquid with high-energy x-rays. Contrary to expectation, branched-chain paraffins produce many more free ions than straight-chain paraffins do, and the ether 1,4-dioxane produced only a third as many free ions as its hydrocarbon analog, cyclohexane.     

Resonant tunneling in the quantum Hall regime: measurement of fractional charge

In experiments on resonant tunneling through a "quantum antidot" (a potential hill) in the quantum Hall (QH) regime, periodic conductance peaks were observed as a function of both magnetic field and back gate voltage. A combination of the two periods constitutes a measurement of the charge of the tunneling particles and implies that charge deficiency on the antidot is quantized in units of the charge of quasi-particles of the surrounding QH condensate. The experimentally determined value of the electron charge e is 1.57 x 10(-19) coulomb = (0.98 +/- 0.03) e for the states v = 1 and v = 2 of the integer QH effect, and the quasi-particle charge is 5.20 x 10(-20) coulomb = (0.325 +/- 0.01)e for the state v = (1/3) of the fractional QH effect.     

Orangutan death and scavenging by pigs

Pongid remains are rarely recovered from tropical rain forests. Observations of a Bornean bearded pig (Sus barbatus) scavenging an orangutan (Pongo pygmaeus) carcass and the recovery of an orangutan skull fragment corroborates evidence from Africa and suggests that the scavenging of wild pigs may play an important role in the destruction of pongid remains.     

Nondestructive measurement of internal quality of Nanfeng mandarin fruit by charge coupled device near infrared spectroscopy

The soluble solids content (SSC) and total acidity (TA) are the major characteristics for assessing quality and maturity of Nanfeng mandarin fruits. The feasibility of charge coupled device near infrared spectroscopy (CCD-NIRS) combining with effective wavelengths selection algorithm used to measure SSC and TA nondestructively was investigated. The effective wavelengths to SSC and TA were chosen by interval partial least squares (iPLS) in the wavelength range of 600–980 nm. The predictive ability of SSC model used PLS regression was improved with r of 0.92 and RMSEP of 0.65 °Brix using effective wavelengths of 681.36–740.51 nm, 798.60–836.19 nm and 945.52–962.75 nm. The TA model was simplified with r of 0.64 and RMSEP of 0.09% using effective wavelengths of 817.57–836.19 nm, 909.85–927.60 nm and 945.52–962.75 nm. The experimental results demonstrated that the CCD-NIRS technique combining with iPLS algorithm was a feasible method to measure SSC and TA of Nanfeng mandarin fruits nondestructively.     

苹果醋清除DPPH自由基活性成分的研究

以苹果、酵母菌和醋酸菌为试验材料,采用不同的发酵工艺,对4种苹果醋样品进行抗氧化活性成分分析和DPPH自由基清除率的测定,研究其主要活性成分含量与DPPH自由基清除率之间的相关性.结果表明:苹果醋具有较高的抗氧化活性成分和较强的抗氧化能力,其中固态发酵苹果醋中总酚、总黄酮含量分别达到2.14、2.19 mg/mL;当加...     

Cavitation in liquids demonstrated by ultrashort-exposure radiography

Using a field-emission x-ray tube, giving a much shorter pulse of rays than does conventional apparatus, we have demonstrated around a water jet the presence of a toroidal cavity that could not be detected visually. One advantage of this method of demonstrating cavitation is that it may be used with fluids and vessels that are opaque to light.     

Absorption of solar radiation by clouds: observations versus models

There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.     

Observation of charge transport by negatively charged excitons

We report transport of electron-hole complexes in semiconductor quantum wells under applied electric fields. Negatively charged excitons (X-), created by laser excitation of a high electron mobility transistor, are observed to drift upon applying a voltage between the source and drain. In contrast, neutral excitons do not drift under similar conditions. The X- mobility is found to be as high as 6.5 x 10(4) cm2 V-1 s-1. The results demonstrate that X- exists as a free particle in the best-quality samples and suggest that light emission from opto-electronic devices can be manipulated through exciton drift under applied electric fields.     

Azotobacter cysts: reactivation by white light after inactivation by ultraviolet radiation

Cysts of Azotobacter vinelandii 12837 inactivated by ultraviolet radiation can be reactivated by white light. This photoreactivation mechanism is not seen in the vegetative cells of the same organism.     

Chick interferon: heterogeneity of electric charge

Chick interferon from allantoic fluid, virus-induced and partly purified, consists of several active components of different charge. The components are separable by elution at different pH values from a carboxymethyl-Sephadex column; they also occupy different pH zones in electrofocusing gradients. Most of the interferon is, however, isoelectric near neutrality.     

Soil-water potential: direct measurement by a new technique

Current methods of measuring the potential of water in soil are inadequate. It is proposed to depress the reference free energy of water by a predetermined amount from the standard level of pure free water at atmospheric pressure by use of a solute. The specific free-energy difference of soil water from the depressed reference can be measured as a pressure.     

Motions of molecules in liquids: viscosity and diffusivity

The fluidity of a simple liquid is proportional to its degree of expansion over the volume, V(0), at which its molecules are so crowded as to inhibit self-diffusion and viscous (as distinguished from plastic) flow. The equation of proportionality is 1/eta = B[(V - V(0))/V(0)] where eta is the viscosity and V is the molal volume. Values of B are the same for normal paraffins from C(3)H(8) to C(7)H(16) and then decrease progressively as the paraffin lengths increase. Values for other liquids, C(6)H(6), CCl(4), P(4), CS(2), CHCl(3), and Hg, appear to vary with repulsive forces. liquids can be moderately fluid when expanded by less than 10 percent; this shows the unreality of some theoretical treatments of the liquid state. Diffusivity begins from the temperature at which V equals V(0) and can be correlated for temperature dependence, and for solute-solvent interrelations.     

Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation

Suitably brief pulses of selectively absorbed optical radiation can cause selective damage to pigmented structures, cells, and organelles in vivo. Precise aiming is unnecessary in this unique form of radiation injury because inherent optical and thermal properties provide target selectivity. A simple, predictive model is presented. Selective damage to cutaneous microvessels and to melanosomes within melanocytes is shown after 577-nanometer (3 x 10(-7) second) and 351-nanometer (2 x 10(-8) second) pulses, respectively. Hemodynamic, histological, and ultrastructural responses are discussed.     

发酵香肠辐照保质研究

以不同剂量辐照处理发酵香肠,检测菌落总数和感观品质;以水分活度、水分含量、pH值、含盐量、氨基酸总量、非蛋白氮、总氮、硫代巴比妥酸值、挥发性风味化合物、肌浆蛋白与肌原纤维蛋白等为指标,研究辐照对发酵香肠品质的影响。结果表明,4 kGy以上辐照处理在第90 d时菌落总数在1.2×103CFU/g以下,低于国家标准限定值,感观品质可接受;不同剂量辐照后水分含量差异显著(P<0.05),氯化钠含量差异不显著(P>0.05);0～2kGy辐照后发酵香肠的pH值显著高于4～6 kGy辐照处理;辐照使发酵香肠中风味物质含量及种类、肌浆蛋白和肌原纤维蛋白含量均高于未辐照的发酵香肠。     

Disulfide interchange by ionizing radiation

The irradiation of a soluition of two symmetric disulfides produces detectable amounts of the nonsymmetric mixed disulfide. The effect is abolished by the addition of ethylmaleimide. The finding indicates that radiation caulses a disulfide opening and recombining process which may be of radiobiological interest.     

凤凰茶体外清除亚硝酸盐及阻断亚硝胺合成的研究

在体外模拟胃液(pH=3、37℃)的试验条件下,研究潮州菜常用料中凤凰茶(1%)对亚硝酸盐的清除及阻断亚硝胺合成的能力,并与Vc进行比较。结果表明,凤凰茶对清除亚硝酸盐及阻断亚硝胺的化学合成具有良好效果,其最大清除率为62.83%,最大阻断率为45.05%。     

Retina: ultrastructural alterations produced by extremely low levels of coherent radiation

The effect of low levels of coherent radiation on the eye is not fully established, but is generally presumed to be noninjurious. Irradiation of the retina with a Q-switched ruby laser emitting low amounts of energy (0.1 percent probability of creating damage) consistently produces ultrastructural alterations in rods and cones. Outer segments of these cells are broken and disorganized and their lamellae are in disarray 1 day after such irradiation.     

Flocculation mechanism: charge neutralization and bridging

Electrophoresis measurements and electron-microscope observations with two model colloids and a polymeric flocculant show zeta-potential changes and details of floc structure. Fibers of the flocculant extend radially from the particle surface and vary in thickness from 20 to 300 angstroms. Both charge neutralization and bridging may function simultaneously.