Ionizing radiation decreases veratridine-stimulated uptake of sodium in rat brain synaptosomes

Veratridine-stimulated uptake of sodium-22 in brain synaptosomes was significantly reduced by ionizing radiation over a dose range of 10 to 1000 rads. The response was dose-dependent and involved a decrease in the maximum effect of veratridine on uptake. The central nervous system may be more sensitive to ionizing radiation than generally thought, perhaps through a loss of the ability of the sodium channel to respond properly to stimulation.     

芽胞杆菌分类研究进展

芽胞杆菌属Bacillus是一类产芽胞的革兰氏阳性细菌,好氧或兼性厌氧生活,产生具有抗逆性球形或椭圆形芽胞.芽胞对高温、紫外线、干燥、电离辐射和很多有毒的化学物质都有很强的抗性.由于芽胞的特性,使得芽胞杆菌的分类研究越来越重要.《国际系统与进化微生物学杂志》是由普通微生物学会(SGM)出版的,是国际微生物分类学界公认的...     

Dosimetry of Atomic Bomb Radiation in Hiroshima by Thermoluminescence of Roof Tiles

Thermoluminescence dosimetry is a powerful tool for obtaining the distribution of gamma dose, heretofore unknown, from the atomic bombs dropped on Hiroshima and Nagasaki. Roof tiles irradiated by the bombs show intense thermoluminescence, and the radiation dose for samples irradiated below 100 r by the bomb can be measured by this method.     

Accumulation of Mn(II) in Deinococcus radiodurans facilitates gamma-radiation resistance

Deinococcus radiodurans is extremely resistant to ionizing radiation. How this bacterium can grow under chronic gamma radiation [50 grays (Gy) per hour] or recover from acute doses greater than 10 kGy is unknown. We show that D. radiodurans accumulates very high intracellular manganese and low iron levels compared with radiation-sensitive bacteria and that resistance exhibits a concentration-dependent response to manganous chloride [Mn(II)]. Among the most radiation-resistant bacterial groups reported, Deinococcus, Enterococcus, Lactobacillus, and cyanobacteria accumulate Mn(II). In contrast, Shewanella oneidensis and Pseudomonas putida have high iron but low intracellular manganese concentrations and are very sensitive. We propose that Mn(II) accumulation facilitates recovery from radiation injury.     

Iron in synthetic quartz: heat and radiation induced changes

As part of a study of the possible changes in silicate material on the lunar surface produced by solar radiation, effects of ionizing radiation, of heating, and of heating followed by ionizing radiation on iron-doped synthetic quartzes have been studied as models. The optical changes are mainly related to valence changes in ferric or ferrous ions.     

辐射对黑麦根尖细胞亚显微结构的影响

用15,000伦琴之 Co~(60)γ射线,照射黑麦根尖细胞,超薄切片后,进行电镜观察发现:细胞质内强烈液泡化。其原因可能是内质网的膨大和线拉体内嵴的消失衍变而成;线粒体内外膜和嵴受到破坏,发生变形;细胞核分散成微核。这些将对细胞的生命活动带来很大影响。     

Solid-state photoelectron spectroscopy with synchrotron radiation

Synchrotron radiation sources, providing intense, tunable, polarized, and stable beams of ultraviolet and x-ray photons, are having a great impact on biology, physics, chemistry, materials science, and other areas of research. Synchrotron radiation has revolutionized solid-state photoelectron spectroscopy by enhancing its capabilities for investigating the electronic behavior of solids and solid surfaces. Several fundamental photoemission techniques that rely on synchrotron radiation are discussed in this article. These techniques have an adjustable tunable surface sensitivity and provide the first direct mapping of the electronic band structure. Recent applications of photoelectron spectroscopy for studies of chemisorption geometries and surface structures are discussed.     

Time-resolved holography with photoelectrons

Ionization is the dominant response of atoms and molecules to intense laser fields and is at the basis of several important techniques, such as the generation of attosecond pulses that allow the measurement of electron motion in real time. We present experiments in which metastable xenon atoms were ionized with intense 7-micrometer laser pulses from a free-electron laser. Holographic structures were observed that record underlying electron dynamics on a sublaser-cycle time scale, enabling photoelectron spectroscopy with a time resolution of almost two orders of magnitude higher than the duration of the ionizing pulse.     

Velocity of Light and Measurement of Interplanetary Distances

The combined availability of atomic clocks and of instrumented planetoids traveling in their own solar orbits will offer the possibility of determining their distance from us, and hence interplanetary distances, in terms of the wavelength of the radiation of atomic frequency standards. It can be anticipated that the accuracy of these measurements will be very high and will not depend upon our less accurate knowledge of the velocity of light in terms of the standard meter, the sidereal second, and so on.     

Phosphorescence of rat kidneys cooled in liquid nitrogen

Cut surfaces of rat kidneys exhibit intense, reproducible, and very detailed phosphorescent patterns after they are cooled with liquid nitrogen and then exposed to shortwave ultraviolet radiation. Ligation of the renal blood vessels for a period of 6 to 24 hours destroys most of this phosphorescence, whereas a ligation of the ureter has no effect on kidney phosphorescence.     

Ultrafast X-ray Pulses from Laser-Produced Plasmas

A high-temperature plasma is created when an intense laser pulse is focused onto the surface of a solid. An ultrafast pulse of x-ray radiation is emitted from such a plasma when the laser pulse length is less than a picosecond. A high-speed streak camera detector was used to determine the duration of these x-ray pulses, and computer simulations of the plasmas agree with the experimental results. Scaling laws predict that brighter and more efficient x-ray sources will be obtained by the use of more intense laser pulses. These sources can be used for time-resolved x-ray scattering studies and for the development of x-ray lasers.     

玉米诱变育种研究进展

简述了电离辐射和化学诱变等玉米诱变育种方法,对激光辐照诱变育种和EMS花粉诱变育种等发展较快的新技术作了较详细的阐述。     

The ras oncogenes increase the intrinsic resistance of NIH 3T3 cells to ionizing radiation

Identification of genes that function to protect cells from radiation damage is an essential step in understanding the molecular mechanisms by which mammalian cells cope with ionizing radiation. The intrinsic radiation resistance (D0) of NIH 3T3 cells was markedly and significantly increased by transformation with ras oncogenes activated by missense mutations. This radiobiologic activity appeared to be a specific consequence of the ras mutations rather than of transformation, since revertant cells that contained functional ras genes (but were no longer phenotypically transformed) retained their increased D0's.     

电离辐射生物学效应及其在农业上的应用

本文对电离辐射生物学效应及其作用机制做了简要概述，并就其在辐射育种、农产品加工、防治害虫、刺激增产、同位素技术等方面的应用做了简单介绍。     

Electroencephalographic responses to ionizing radiation

Electroencephalographic recordings made from chronically implanted cortical electrodes indicate that ionizing radiation has an immediate effect upon brain wave patterns. X-rays delivered at the rate of 0.2 roentgen per second produce an arousal effect resembling that which occurs as a result of stimulation through peripheral receptor systems.     

Antihistamines block radiation-induced taste aversions

When rats are treated with an antihistamine prior to being given sublethal doses of ionizing radiation, the formation of a conditioned saccharin aversion is completely inhibited. A profound aversion could be conditioned with histamine diphosphate as the aversive stimulus. The increase in histamine production after radiation exposure represents the physiological basis of radiation-induced taste aversions.     

Suppression of collisional shifts in a strongly interacting lattice clock

Optical lattice clocks with extremely stable frequency are possible when many atoms are interrogated simultaneously, but this precision may come at the cost of systematic inaccuracy resulting from atomic interactions. Density-dependent frequency shifts can occur even in a clock that uses fermionic atoms if they are subject to inhomogeneous optical excitation. However, sufficiently strong interactions can suppress collisional shifts in lattice sites containing more than one atom. We demonstrated the effectiveness of this approach with a strontium lattice clock by reducing both the collisional frequency shift and its uncertainty to the level of 10(-17). This result eliminates the compromise between precision and accuracy in a many-particle system; both will continue to improve as the number of particles increases.     

Millisecond Pulsar PSR 1937+21: A Highly Stable Clock

The stable rotation and sharp radio pulses of PSR 1937+21 make this pulsar a clock whose long-term frequency stability approaches and may exceed that of the best atomic clocks. Improvements in measurement techniques now permit pulse arrival times to be determined in 1 hour at the Arecibo radio telescope with uncertainties of about 300 nanoseconds relative to atomic time. Measurements taken approximately every 2 weeks since November 1982 yield estimates of fractional frequency stability that continue to improve with increasing averaging time. The pulsar's frequency stability is at least as good as 6 x 10(-14) for averaging times longer than 4 months, and over the longest intervals the measurements appear to be limited by the stability of the reference atomic docks. The data yield a firm upper limit of 7 x 10(-36) gram per cubic centimeter for the energy density of a cosmic background of gravitational radiation at frequencies of about 0.23 cycle per year. This limit corresponds to approximately 4 x 10(-7) of the density required to close the universe.     

Energetic radiation produced during rocket-triggered lightning

Using a NaI(Tl) scintillation detector designed to operate in electrically noisy environments, we observed intense bursts of energetic radiation (> 10 kiloelectron volts) during the dart leader phase of rocket-triggered lightning, just before and possibly at the very start of 31 out of the 37 return strokes measured. The bursts had typical durations of less than 100 microseconds and deposited many tens of megaelectron volts into the detector. These results provide strong evidence that the production of runaway electrons is an important process during lightning.     

Endogenous opiates mediate radiogenic behavioral change

Exposure of C57BL/6J mice to ionizing radiation caused stereotypical locomotor hyperactivity similar to that produced by morphine. Naloxone administration prevented this radiation-induced behavioral activation. These results support the hypothesis that endorphins are involved in some aspects of radiogenic behavioral change.