RESULTS The elimination rate of the air bacteria,the small dust particle(≥0.5μm) and the big one(≥5.0μm) was 90.17%,29.43% and 90.42% at 20 min,respectively. But up to 1h there were 90.17%,52.63% and 94.64%,respectively.

The temperature of dust grains, low temperature and high temperature ions and the number densities of the ions influence the property of dust acoustic waves.

In the sampled 200 homes, the proportion of homes with Dff F3 level of >10 μg/g was 57^0%, 29^5% for group of 2-10 μg/g, and 13^5% for group of <2 μg/g.

The parameters considered are the applied high voltage U, the air flow F, and the quantity of dust in air m.

The Einstein gravitational equations in the spherically symmetric case and for the dust model (i.e., p = 0) have been studied by several authors.

In this case, the mixture area consists of abrasive dust from friction pairs, and the surface film is distributed with crumby hard granules, exiguous oxide, carbide granules and sheared slender fibre.

The values of optimal fiber radii are determined from the condition of maximal dust capacity of a filter at given limiting pressure drop and total initial efficiency.

On the Possible Existence of Radiation Dust Belts in Near-Earth Space

The band structure of α-MoTe2 by photoelectron spectroscopy

Vacuum-cleaved single crystals of α-MoTe2 have been investigated by photoelectron spectroscopy.

The increasing number of biomaterials for the skeletal system requires mote and move their distinct clinical application.

The most abundant fish larvae during this period were preflexion stage mote sculpins (Normanichthyidae) and newly hatched and preflexion stage anchovies (Engraulidae).

A second, smaller summer peak was dominated by preflexion stage anchovies, followed by preflexion stage mote sculpins.

The density of the Galactic meteoroid background formed by the loss of large dust grains escaped from circumstellar disks during the formation of a star is estimated.

The temperature of nonspherical circumstellar dust grains

The temperatures of prolate and oblate spheroidal dust grains in the envelopes of stars of various spectral types are calculated.

Porous dust grains in the shells of Herbig Ae/Be stars

The masses and sizes of dust grains were estimated.

The structure of cometary dust tails is studied in the frame of mechanical theory with special regards to threedimensional treatment of the problem. We begin with the reexamination of orbit mechanics of cometary particles to derive a set of formulae convenient to subsequent discussions and calculations.Mak- ing use of Hamilton's integral b,we have obtained,for example,the equation of orbit in a vectorial form with generalization respecting to force parameter μ(Part 2).On the basis of Part 2,we consider such...

The structure of cometary dust tails is studied in the frame of mechanical theory with special regards to threedimensional treatment of the problem. We begin with the reexamination of orbit mechanics of cometary particles to derive a set of formulae convenient to subsequent discussions and calculations.Mak- ing use of Hamilton's integral b,we have obtained,for example,the equation of orbit in a vectorial form with generalization respecting to force parameter μ(Part 2).On the basis of Part 2,we consider such problems as follows:the relation between initial conditions together with μ and the orbit characteristics;the algorithm for computer-calculation of the motion of particles some interesting features of ele- mentary space distributions vertical motion relative to the comet orbit plane and its implications to the tail structure. Arguments given in §2.5 yield two important results.One is a criterion to check the applicability of the FP(Finson and Probstein)-method.The other con- cerns with the somewhat peculiar structure to appears in the dust tail of comet after perihelion passage,which might be termed as《Neck-line structure(henceforce ab- breviated to NLS)》. In Part 3,we present a new interpretation of the anomalous tails refered to the concept of NLS.A discussion of the development of NLS is given,and it is shown that the emergence and development of NLS can provide an adequate expla- nation for the behaviour of the anomalous tail of C/Arend-Roland,1957 Ⅲ.Fur- thermore,statistical consideration on the visibility of anomalous sunward tail is at- tempted,the result of which also shows that the NLS-interpretation seems to be compatible with the data since 1801. In Part4,we develop a new method for numerical analysis of tail brightness. The basic idea of this method is to combine exact treatment of the motion of a large number of sample particles and counting-technique to estimate the surface brightness integral,taking account of the dust emission characteristics of comets which may be expressed by three source functions,namely,the emission rate N_d(t),the modified size-distribution f(γ;t),and the velocity distribution where Ψ(v;r,t)γ=1-μ). Distribution of tail brightness thus obtained gives essentially the exact solution for the assigned source funtions,in the sense that it is not affected by any auxiliary approximations.Moreover,no difficulties arise in the handling of source functions, because the requisite procedure can be reduced to the sampling of values of relevant parameters;thus the present method is applicable equally well for the case of ani- sotropic emission. In an application of the method for C/Arend-RolandPart4),we suppose that the emission rate varies as the inverse-square of heliocentric distanceN_d(t)∝[rc(t)]~(-2)), and that the velocity distribution is characterized as the isotropic one with a unique speed vo(t,γ).The function f(γ;t)is left as one to be determined through the comparison with observation. The function f(r)for C/Arend-Roland,derived by neglecting its time-dependency, is shown in Fig.16.The corresponding brightness probiles are compared with observed ones in Figs.14 and 15,for Apr.28 and Apr.30,respectively,it is worth noting that both main and anomalous tails have been treated in a unified manner, that is,without any temporal anomalies in emission characteristics. With these results,we conclude:(1)The simple forms presupposed for two functionsN_d(t)and Ψ(v;γ,t))may be well accepted as first approximations;(2) The derived function f(γ)shows its broad peak around γ=0.10～0.12 and possibly a secondary peak around γ～0.015;(3)The present brightness analysis adds support, in a quantitative way,to the NLS-interpretation of the.anomalous tails;(4)More observational data and careful analyses are needed,however,to establish the dust emission characteristics of comets.It is hoped that methods and viewpoints described in the present article may serve as the basis for future investigations.

This article introduces a pneumatic bridge in adverse circumstances. The bridge may retain its equilibrium with variating supply, and free from block up while the measuring object is in a dusty environment and the supply is in a negative pressure.The va(?)iating supply cannot effect the equilibrium of the pneumatic bridge while the ratios of the exponents of the bridge-arms are equal. In addition, an alternating bias pneumatic bridge is designed to avoid block up.

Arising from development of techniques in millimeter wave and infrared observatory, one can find a series complexes consist of HII regions-infrared sources-molecular clouds. W40 (G28. 8+3.5) is a complex which has already been detected by G. Westerhout, E. C. Reifenstein et al, H. Olthof and M. Zeilik et al. Basing upon these data we derived the basic physical parameters, we also calculated the cooling and heating rates for the gas and dust in W40. Finally we discussed the problems about the exchange and trasfer...

Arising from development of techniques in millimeter wave and infrared observatory, one can find a series complexes consist of HII regions-infrared sources-molecular clouds. W40 (G28. 8+3.5) is a complex which has already been detected by G. Westerhout, E. C. Reifenstein et al, H. Olthof and M. Zeilik et al. Basing upon these data we derived the basic physical parameters, we also calculated the cooling and heating rates for the gas and dust in W40. Finally we discussed the problems about the exchange and trasfer of energy among the component of W40 and the origin source.1. The physical parameters of the molecular cloud.Taking geometrical assumptions which had been used by J. Evans et al. As Fig 1 shows, an interior to a given contour level is the projected area of a sphere which has a radio ri=0.056 ai1/4, a surface area Si=4ai and a volume Vi=0.75 ai3/2. These regions are assumed to form a series of concentric shell with volume △Vi=Vi-Vi-1, each with uniform physical properties. The dimension of W40 is adopted 0.7 kpc.In collapsing cloud T=∞, Tk=Tex for the line of 12CO, so the kinetic temperature Tk (col. 3 of the table) can be directly derived from the antenna temperature TA* of 12CO.hereThe colum density of 13COn13L=5.6×1016/cm2. Using the formula nH2L==5.0×l05n13L for W40 we get the column density of H2nH2 L=2.8×1022/cm22. Taking L as the diameter of the sphere in which TA*=15 K we obtained nH2=6.7×103/cm3.From the empirical relation τFIR=10-18 n13 L, We find τFIR=0.056 at the centre of W40. Using the data reported by H. 01 thof we calculated the infrared luminosity in 20-200 μm band L20-200μm = 3.3×104L⊙.2. Energy transformation process of molecular clouds.We 11 respectively consider the two separate systems of gas and dust.(1) Energy relation for the gas.The cooling of H2 is primary through collision of CO with H2 molecular, in which energy is given to CO molecular, then it carried away out of cloud by emission of rotation line of CO molecule. Using the formula given by N. J. Evans we can calculate the. cooling rate of per shell of the contour map of W40 is (erg/cm2 ·s) and the total cooling rate of gas isFor the heating of the gas we consided two mechanisms which can supply it with the equal amount thermal energy with that carried away by CO emission. One is the collapse heating. From V(dE/dt)collapse= PheatingdV/dt and the expression of τff given by N.J. Evans we obtained that the temperature of W40 could maintain at 12.46 K.Another possible mechanism is the inelastic collision of dust with gas. The dust heated by the embeded infrared source transfers some energy to the gas in the collision. The supply energy efficiency of collision dust- gas may be represented by the collisionrelaxation time of dust-gas tr =1/vH,Ndσd Take criterion valuethus tr=4.5×1016NH2-1Tk-1/2s (here vH2 is mean thermal motion velocity of molecular hydrogen). This accords with expression by P. Goldreich and J. Kwan. As regards W40 central region tr=1.15×1012 s which is of the order just as τff. In the central region the cloud heated by dust just as it heated by collapse is rather primary mechanism.(2) Energy relation of dust.The dust in molecular cloud absorb the energy from the embeded IR sources, then they loss the energy by thermal radiation and by providing energy to gas. The balance between both keeps the dust is constant temperature.We derived the dust temperature of a shell in which the radius changes fromWhere the units of L and n are L ⊙ and pc respectively. For W40 the embeded sources emit infrared luminosity L is 3.3×104 L⊙ (Z-200μm), its Tdi is shown in column(6) of the table.There are two cooling mechanisms for the dust. One is the energy transters to gas by inelastic collisions of gas molecular and dust grains, as above, the total transferred energy Cdust-gas < 0.46L⊙. The another is the energy released by the thermal radiation of the dust. The power of thermal radiation is Ciradiation= σTd4Tisi, here si is the surface area of the shell, Ti is the mean optical depth of the shell through out fra-infrared