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1.
In urban areas, the quantity of exhaust particles from vehicle emissions is tremendous and has been regarded as the main contributor to particulate matter (PM) pollution. Recently, the nano-sized PM on public health has begun to raise the attention. The increased toxicity of nanoparticulate can be largely explained by their small size, high airborne concentration, extensive surface area and high content of organic carbon and transition metals. We have attempted to address the toxicity of nano sized-particlulate matter by comparing various particulates including micro-SiO2 (mSiO2), nano-SiO2 (nSiO2), micro-TiO2 (mTiO2), and nano-TiO2 (nTiO2) in RAW264.7 cells and in vivo. The cell viability of all particulates decreased dose dependently. 24-h incubation with nSiO2 demonstrated apoptosis in RAW264.7 using Annexin-V binding immunofluorescent microscopy, but not in any other particulates. In vivo, cytotoxicity of nanosized was higher than micro-sized particulates. As higher the concentration of particulates, the more pulmonary injury and neutrophilic infiltration were observed in nano-sized than micro-sized particulates, respectively. Particularly, 5.0 mg/kg of mTiO2 never shows any increase of neutrophile even with high cellularity of total cells and macrophages. From these results, we suggested that particulate-induced respiratory toxicity be influenced by component, size, and dose of particulates including the characteristic nature of the target cells in vitro and in vivo.  相似文献   

2.
Focusing in solids and application in acoustic imaging   总被引:1,自引:0,他引:1  
Focusing in solids by surface transducer arrays(STA)and the acousticfield distribution on the focal axis are studied in this paper.The relation betweenthe source element width and the field strength at different order focuses is alsodiscussed.Numerical calculation is used to get the focal field distribution as theelement width is changed.Some practical problems such as the minimumdistinguishable frequency,the transversal and longitudinal resolution are investi-gated when this kind of focusing is used for NDT and acoustic imaging.Someexplorative experiments have been done to demonstrate the theory.  相似文献   

3.
Recent experiments at LEAR have found surprisingly large branching ratios for reactions $\bar NN \to \phi \pi $ from S-wave initial states while noφπ production is observed from P states of the $\bar pp$ system. Also, noφπ is seen in radiative J/ψ decays even though the rate forωπ is substantial. We calculate theφπ production rates for these three cases viaKK* intermediate states and $K\bar K$ rescattering using the dispersion relation technique; we find that the largeφπ rate in $\bar pp$ annihilations from S states can be reproduced with a reasonable cut-off for the dispersion integral; for J/ψ decays the calculatedφπ rate is compatible with the observed upper limit. We would, however, expectφπ to be seen from $\bar pp$ P-states, in contrast to experimental findings. Yet the branching ratio for $\bar pp \to K*\bar K$ via isospinI = 1 of $\bar pp$ ,1 P 1 state is not known; and therefore no definite conclusion can be drawn. We also compare the Dalitz plots we obtain for directφ production and forφ production via rescattering. Clear differences between the two theoretical distributions are observed; yet very high precision data would be required to establish the origin — direct production or rescattering — of theφ mesons. This observation supports the use of the isobar model in data analyses.  相似文献   

4.

Background  

In order to confirm the roles of creatine (Cr) in epilepsy, we investigated the anti-convulsive effects of Cr, creatine transporter (CRT) and creatine kinases (CKs) against chemical-induced acute seizure activity and chronic epileptic seizure activity.  相似文献   

5.
The g-factors of some members of the ground state band and of the 2+ state in the %-vibrational band have been measured in 160,162,164Dy using the Coulomb Excitation Transient Field technique, induced by 58Ni projectiles at 230, 210 and 217 MeV, respectively. The g-factors in the ground state band are consistent with a constant value, while that of the 2+% states is about 20% larger in average than those in the ground state band. Results are discussed in the frame of the systematics in this nuclear region.  相似文献   

6.
7.
We investigate the electron transport in silicene with both staggered electric potential and magnetization; the latter comes from the magnetic proximity effect by depositing silicene on a magnetic insulator. It is shown that the silicene could be a spin and valley half metal under appropriate parameters when the spin-orbit interaction is considered; further, the filtered spin and valley could be controlled by modulating the staggered potential or magnetization. It is also found that in the spin-valve structure of silicene, not only can the antiparallel magnetization configuration significantly reduce the valve-structure conductance, but the reversing staggered electric potential can cause a high-performance magnetoresistance due to the spin and valley blocking effects. Our findings show that the silicene might be an ideal basis for the spin and valley filter analyzer devices.  相似文献   

8.
Most of the measured events on hydrogen, deuterium and neon targets from BEBC at CERN and the 15-foot Bubble Chamber at Fermilab are combined to measure spin-density matrix elements for 0 production in the current-fragmentation region in neutrino and antineutrino charged-current interactions. The spin-alignment parameter is found to be 0.08±0.11 for neutrino and 0.41±0.11 for antineutrino interactions. The parity-odd density matrix element Im(10+–10) is consistent with zero in both reactions. In the combined neutrino and antineutrino data an indication of parity violation is observed: Im 1–1=0.38±0.16 atx B >0.2,Q 2>8 GeV2 andz>0.6.  相似文献   

9.
The temperature dependence of the piezoelectric stress-constant, the piezoelectric strain-constant, and the Young's elastic constant is simultaneously determined for homopolymers and copolymers of γ-benzyl-L-glutamate [Glu(OBz)] and L-leucine (Leu). With the rise of temperature, the piezoelectric constants first increase due to the elastic relaxation in the Leu side chains (about ?150°C) and the Glu(OBz) side chains (about ?10°C), and then decrease due to the dielectric relaxation in the Glu(OBz) side chains. Higher piezoelectric constants are observed for the copolymers at low temperatures. This suggests that the shear-induced internal strain of the peptide dipoles is enhanced by heterogenity in the structure of side chains.  相似文献   

10.

EditorialSpecial issue

Advances in optoelectronics in europe—the RACE and ESPRIT programmes  相似文献   

11.
In this paper, we present the decoupling bang-bang (BB) twin-born pulses to suppress the genera/deco- herence, both amplitude and phase decoherence, in a three-level atom in V- and Ξ-configurations. We give the exact sequence of periodic twinborn pulses in such systems.  相似文献   

12.
The correspondence between quantum level spacing distributions and classical motion of 1-D PT symmetric non-Hermitian systems is investigated using two PT symmetric complex potentials- complex rational power potential V1(x) = (ix)^(2n 1)/m and genera/polynomial potential V2(x) =x^2M ib1x^2M-1 b2x^2M-2 … ib2M-1x. The level spacing distribution of V1 has two forms. When 2n 1-2m is positive, the level spacing distribution of real eigen values assumes a decreasing power function, while it behaves as an increasing power function when 2n 1-2m is negative.The PT symmetry of this system is spontaneously broken as 2n 1 - 2m becomes negative. This change manifests itself in classical mechanics as it is found by Bender et al. However, it was found that the change in the form of level spacing distribution mentioned above is not due to the spontaneous breaking down of PT symmetry. Level spacing distribution of V2 assumes an increasing power function when order of the polynomial is greater than two.  相似文献   

13.
1 Introduction  Thenegative groupdelaydispersion(GDD) providedbyapairofprismordoubleprismshasplayedanimportantroleinintracavity[1] orextracavity[2 ] dispersioncompensationforultra shortpulse generationduetoitsadvantages,suchaslowloss,easyalignmentandcompactne…  相似文献   

14.
15.
Investigation results on linear and non-linear optical properties, damage threshold and potential efficiencies of biaxial negative LiInS2 crystal are represented. It shows that the crystal has phase-matching and group-velocity matching in wide spectral range for second harmonic, sum- and difference-frequency generation of visible, near and middle IR lasers. The possibilities of designing middle IR optical parametric oscillator (OPO) pumped by Nd:YAG and dye lasers and specially possibility of frequency conversion with 3 um range femtosecond erbium lasers are given.  相似文献   

16.
Squeezing and Entanglement in Continuous Variable Systems   总被引:2,自引:0,他引:2       下载免费PDF全文
夏云杰  郭光灿 《中国物理快报》2004,21(10):1877-1880
Based on total variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators, the generalized EPR entangled states in continuous variable systems are defined. We show that such entangled states must correspond to two-mode squeezing states whether these states are Gaussian or not and whether they are pure or not. With help of the relation between the total variance and the entanglement, the degree of such entangIement is also defined. Through analysing some specific cases, we see that this method is very convenient and easy in practical applications. In addition, an entangled state with no squeezing is studied, which reveals that there certainly exists something unknown about entanglement in continuous variable systems.  相似文献   

17.
This paper reviews the studies on acoustoelectric effectin extrinsic semiconductor materials used in various scientific and othermeasurements.A historical review of earlier findings is given with specialreference to associated mechanisms.Acoustoelectric studies in solid statedevioes require further attention and the work done in this area is alsodiscussed.  相似文献   

18.
Fusion technologies and materials researches made progress in the major three aspects in 2006, specially implemented the ITER agreement tasks of first wall (FW) plate fabrication qualification and shield bulk thermal-hydraulic analysis and design, studied on low activation fusion structure materials and High Z plasma facing materials, experimentally investigated on liquid metal blanket magneto-hydrodynamics effects and so on.  相似文献   

19.
I.IntroductionExposuretoenvironmcnta1noisc1cadstoannoyanceande1evationofhearingthrcsho1d.Itisnotpracticetoiso1atesuchthcsenoiscsbyengineeringmethods.Analternativecommonlypractica1andinexpcnsivemethodforhcaringprotectionisthcuseofhcaringprotcctivedcvicespePDs)suchasearplugsandearmuffe.AsdcfinedbyBcrgcr['lthatthenoisereductionpro-videdbyHPDispopu1ar1yrefcrredtoasitsattenuation.InfaCtoricsandindustrialplaceswhcretheworkersareexposedtohazardousnoisc,thcattcnuationofsing1ehearingprotectordevice…  相似文献   

20.
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