Nuclear winter: global consequences of multple nuclear explosions

The potential global atmospheric and climatic consequences of nuclear war are investigated using models previously developed to study the effects of volcanic eruptions. Although the results are necessarily imprecise due to wide range of possible scenaros and uncertainty in physical parameters, the most probable first-order effects are serious. Significant hemispherical attenuation of the solar radiation flux and subfreezing land temperatures may be caused by fine dust raised in high-yield nuclear surface bursts and by smoke from city and forest fires ignited by airbursts of all yields. For many simulated exchanges of several thousand megatons, in which dust and smoke are generated and encircle the earth within 1 to 2 weeks, average light levels can be reduced to a few percent of ambient and land temperatures can reach -15 degrees to -25 degrees C. The yield threshold for major optical and climatic consequences may be very low: only about 100 megatons detonated over major urban centers can create average hemispheric smoke optical depths greater than 2 for weeks and, even in summer, subfreezing land temperatures for months. In a 5000-megaton war, at northern mid-latitude sites remote from targets, radioactive fallout on time scales of days to weeks can lead to chronic mean doses of up to 50 rads from external whole-body gamma-ray exposure, with a likely equal or greater internal dose from biologically active radionuclides. Large horizontal and vertical temperature gradients caused by absorption of sunlight in smoke and dust clouds may greatly accelerate transport of particles and radioactivity from the Northern Hemisphere to the Southern Hemisphere. When combined with the prompt destruction from nuclear blast, fires, and fallout and the later enhancement of solar ultraviolet radiation due to ozone depletion, long-term exposure to cold, dark, and radioactivity could pose a serious threat to human survivors and to other species.     

Planets and Comets: Role of Crystal Growth in Their Formation

The application of crystal growth theory to the formation of smoke particles from the primordial solar nebula indicates that solid particles with filamentary structures would form. Such particles would facilitate successive aggregation into planets, comets, and asteroids. The difficulties associated with the aggregation of spherical smoke particles would thus be avoided.     

Smoke production from multiple nuclear explosions in nonurban areas

The amount of smoke that may be produced by wildland or rural fires as a consequence of a large-scale nuclear exchange is estimated. The calculation is based on a compilation of rural military facilities, identified from a wide variety of unclassified sources, together with data on their geographic positions, surrounding vegetation (fuel), and weather conditions. The ignition area (corrected for fuel moisture) and the amount of fire spread are used to calculate the smoke production. The results show a substantially lower estimated smoke production (from wildland fires) than in earlier "nuclear winter" studies. The amount varies seasonally and at its peak is less by an order of magnitude than the estimated threshold level necessary for a major attenuation of solar radiation.     

Biomass burning in the tropics: impact on atmospheric chemistry and biogeochemical cycles

Biomass burning is widespread, especially in the tropics. It serves to clear land for shifting cultivation, to convert forests to agricultural and pastoral lands, and to remove dry vegetation in order to promote agricultural productivity and the growth of higher yield grasses. Furthermore, much agricultural waste and fuel wood is being combusted, particularly in developing countries. Biomass containing 2 to 5 petagrams of carbon is burned annually (1 petagram = 10(15) grams), producing large amounts of trace gases and aerosol particles that play important roles in atmospheric chemistry and climate. Emissions of carbon monoxide and methane by biomass burning affect the oxidation efficiency of the atmosphere by reacting with hydroxyl radicals, and emissions of nitric oxide and hydrocarbons lead to high ozone concentrations in the tropics during the dry season. Large quantities of smoke particles are produced as well, and these can serve as cloud condensation nuclei. These particles may thus substantially influence cloud microphysical and optical properties, an effect that could have repercussions for the radiation budget and the hydrological cycle in the tropics. Widespread burning may also disturb biogeochemical cycles, especially that of nitrogen. About 50 percent of the nitrogen in the biomass fuel can be released as molecular nitrogen. This pyrdenitrification process causes a sizable loss of fixed nitrogen in tropical ecosystems, in the range of 10 to 20 teragrams per year (1 teragram = 10(12) grams).     

Airborne studies of the smoke from the kuwait oil fires

Airborne studies of smoke from the Kuwait oil fires were carried out in the spring of 1991 when approximately 4.6 million barrels of oil were burning per day. Emissions of sulfur dioxide were approximately 57% of that from electric utilities in the United States; emissions of carbon dioxide were approximately 2% of global emissions; emissions of soot were approximately 3400 metric tons per day. The smoke absorbed approximately 75 to 80% of the sun's radiation in regions of the Persian Gulf. However, the smoke probably had insignificant global effects because (i) particle emissions were less than expected, (ii) the smoke was not as black as expected, (iii) the smoke was not carried high in the atmosphere, and (iv) the smoke had a short atmospheric residence time.     

Myristicin in cigarette smoke

The pharmacologically active aromatic ether, myristicin, was isolated from the smoke of commercial cigarettes. The compound was identified by spectrometry (infrared, ultraviolet, and mass) and gas chromatography. The amount of myristicin in smoke is relatively low, and its contribution, if any, to the physiological action of cigarette smoke is unknowvn.     

Direct Radiative Forcing by Smoke from Biomass Burning

Airborne measurements in smoke from biomass burning in Brazil have yielded optical parameters that permit an improved assessment of the effects of smoke on Earth's radiation balance. The global-mean direct radiative forcing due to smoke from biomass burning worldwide is estimated to be no more than about -0.3 watt per square meter (cooling), compared with +2.45 watts per square meter (warming) due to anthropogenic greenhouse gases. On regional scales, direct radiative forcing due to smoke can be large and might indirectly affect global climate.     

Jupiter's Decametric Radio Emission and the Radiation Belts of Its Galilean Satellites

Many of the observed properties of Jupiter's decametric radiation may be explained by postulation that the inner Galilean satellites of Jupiter have magnetic properties that strongly distort Jupiter's magnetic field in the region of each satellite. Charged particles from Jupiter's radiation belts are trapped by these distorted fields and emit synchrotron radiation.     

Emission of methyl bromide from biomass burning

Bromine is, per atom, far more efficient than chlorine in destroying stratospheric ozone, and methyl bromide is the single largest source of stratospheric bromine. The two main previously known sources of this compound are emissions from the ocean and from the compound's use as an agricultural pesticide. Laboratory biomass combustion experiments showed that methyl bromide was emitted in the smoke from various fuels tested. Methyl bromide was also found in smoke plumes from wildfires in savannas, chaparral, and boreal forest. Global emissions of methyl bromide from biomass burning are estimated to be in the range of 10 to 50 gigagrams per year, which is comparable to the amount produced by ocean emission and pesticide use and represents a major contribution ( approximately 30 percent) to the stratospheric bromine budget.     

Trapped radiation belts of saturn: first look

Pioneer 11 has made the first exploration of the magnetosphere and trapped radiation belts of Saturn. Saturn's magnetosphere is intermediate in size between Earth's and Jupiter's, with trapped particle intensities comparable to Earth's. The outer region of Saturn's magnetosphere contains lower energy radiation and is variable with time; the inner region contains higher energy particles. The pitch angle distributions show a remarkable variety of field-aligned and locally mirroring configurations. The moons and especially the rings of Saturn are effective absorbers of trapped particles; underneath the rings, the trapped radiation is completely absorbed. We confirm the discovery of a new ring, called the F ring, a new division, the Pioneer division, and a moon, called 1979 S 2. The latter has probably been seen from Earth. There may be evidence for more bodies like 1979 S 2, but at this stage the interpretation of the data is ambiguous. Using particle diffusion rates, we estimate that the cross-sectional area of the F ring is > 7 x 10(13) square centimeters and that the opacity is > 10(-5). Cosmic-ray albedo neutron decay should be looked into as a source of energetic particles in the inner magnetosphere of Saturn.     

Behavior of Antarctic Krill, Euphausia superba: Chemoreception, Feeding, Schooling, and Molting

Krill do not feed by passive, continuous filtration but use area-intensive searching and various rapid feeding behaviors to exploit local high food concentrations. Chemicals alone at low concentrations, not particles, trigger feeding. Krill form dense schools that move rapidly and migrate primarily horizontally. Abrupt disruption of a school can trigger mass molting, and molts may act as decoys.     

Polarized gamma-ray emission from the crab

Pulsar systems accelerate particles to immense energies. The detailed functioning of these engines is still poorly understood, but polarization measurements of high-energy radiation may allow us to locate where the particles are accelerated. We have detected polarized gamma rays from the vicinity of the Crab pulsar using data from the spectrometer on the International Gamma-Ray Astrophysics Laboratory satellite. Our results show polarization with an electric vector aligned with the spin axis of the neutron star, demonstrating that a substantial fraction of the high-energy electrons responsible for the polarized photons are produced in a highly ordered structure close to the pulsar.     

浅谈如何使用烟剂有效防治森林病虫害

烟剂是防治森林病虫害的主要手段之一,非常适用于树高、林密、交通不便、水源缺乏的林区。由于药剂转变成烟以后,颗粒变得非常小,能够到达茂密的树冠、叶子的正反面、树皮缝隙等处,大大提高了防治病虫害的效果,所以烟剂防治是一种很有前途的防治方法。     

Amorphous ice on saturnian rings and on icy satellites: its formation, stability, and observability

Saturnian rings and icy satellites may be covered with amorphous rather than crystalline ice. Its likely source is water molecules sputtered by particles in the radiation belts, it may be stable, and its presence could be deduced from the rate of temperature drop in a shadow. Observation of this effect is, however, difficult, especially for the rings. A possible relation to the brightness anisotropy of ring A is pointed out.     

Preparation of submicroscopic spider threads for particle studies

Many small spiders produce threads of different diameters, some of which are submicroscopic. When the threads are subjected to an environment of tobacco smoke and then examined microscopically, the invisible threads are manifested as particles in a line with no visible connection. These threads are used to support microscopic water droplets in single-particle scattering experiments.     

分组加工对配方模块主流烟气及感官质量的影响

[目的]系统地研究干燥模式对卷烟各模块的主流烟气及感官质量的影响。[方法]以干燥模式为着手点,设计试验,从燃烧速率、主流烟气和感官质量3个方面分析研究了干燥模式对卷烟质量的影响。[结果]试验表明,干燥模式对燃烧速率影响显著,进气流干燥的烟丝燃烧速率较薄板干燥的烟丝快,在同是薄板烘丝的条件下,KLD顺流KLD2Z逆流KLD逆流。干燥模式对卷烟主流烟气影响显著,对总粒相物、焦油、烟碱的影响:KLD顺流KLD2Z逆流KLD逆流CTD;对CO的影响:KLD顺流CTDKLD2Z逆流KLD逆流。A组感官质量排序:CTDKLD顺流KLD逆流KLD2Z逆流;B组和C组感官质量排序:KLD2Z逆流KLD顺流KLD逆流CTD。[结论]研究可为卷烟生产选择适宜的工艺路径,进而提高工艺对卷烟产品的贡献率提供参考依据。     

Biogenic potassium salt particles as seeds for secondary organic aerosol in the Amazon

The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.     

潜香物质在低焦油卷烟香味补偿技术中的应用研究

[目的]为解决低焦油卷烟香气量较少、丰富性稍欠等问题。[方法]重点考察乙基香兰素葡萄糖苷作为潜香类物质在"七匹狼"某牌号低焦油卷烟A中的香味补偿作用。[结果]烟气致香成分分析结果表明,乙基香兰素葡萄糖苷作为糖苷类潜香物质,在烟支燃吸过程中可发生热裂解,释放出乙基香兰素和香兰素,而且酮类物质、酸类物质和杂环类物质等烟草致香成分含量都有不同程度的增加;其次,通过单体香料和天然香料的作用评价和筛选,结合潜香类物质乙基香兰素葡萄糖苷完成功能性表香香基设计,并通过与原表香的复配,实现对现有产品的改造。感官特征评价结果表明,改造后卷烟样品香气风格更加突出,丰富性增加,烟气的圆润性和满足感得到了提高。[结论]潜香类物质在低焦油卷烟中能够起到香味补偿作用。     

Radiation Hazard in Space from Solar Particles

There were about six solar flare events during the last solar cycle which would have exposed a space traveler to serious radiation from solar particles. The radiation from two of these events was intense enough to necessitate extra precautions being taken to protect space travelers.     

Viking magnetic properties investigation: further results

The amounts of magnetic particles held on the reference test chart and backhoe magnets on lander 2 and lander 1 are comparable, indicating the presence of an estimated 3 to 7 percent by weight of relatively pure, strongly magnetic particles in the soil at the lander 2 sampling site. Preliminary spectrophotometric analysis of the material held on the backhoe magnets on lander 1 indicates that its reflectance characteristics are indistinguishable from material within a sampling trench with which it has been compared. The material on the RTC magnet shows a different spectrum, but it is suspected that the difference is the result of a reflectance contribution from the magnesium metal covering on the magnet. It is argued that the results indicate the presence, now or originally, of magnetite, which may be titaniferous.