DC discharges in atmospheric air for bio-decontamination – spectroscopic methods for mechanism identification

Three types of DC electrical discharges in atmospheric air (streamer corona, transient spark and glow discharge) were tested for bio-decontamination of bacteria and yeasts in water solution, and spores on surfaces. Static vs. flowing treatment of contaminated water were compared, in the latter the flowing water either covered the grounded electrode or passed through the high voltage needle electrode. The bacteria were killed most efficiently in the flowing regime by transient spark. Streamer corona was efficient when the treated medium flew through the active corona region. The spores on plastic foil and paper surfaces were successfully inactivated by negative corona. The microbes were handled and their population evaluated by standard microbiology cultivation procedures. The emission spectroscopy of the discharges and TBARS (thiobarbituric acid reactive substances) absorption spectrometric detection of the products of lipid peroxidation of bacterial cell membranes indicated a major role of radicals and reactive oxygen species among the bio-decontamination mechanisms.     

Safe-Disposing of NaK in LMEL for Facility Modified

A series of experimental studies on MHD effects in circular and rectasgular pipe of conducting and insulating wall, have been carried out on liquid metal experimental loop （ LMEL ）,sodium potassium alloy （ NaK ） reacts actively with oxygen in air,     

Critical exponentβ for hyperfine fields in nickel

The magnetic hyperfine fields for⁶³Ni,⁶⁶Cu, and⁶⁷Zn nuclei in nickel metal have been measured by means of perturbed-ray angular distribution techniques at different temperatures up to 1 K below the Curie temperature,T _C . The temperature dependence of the fields can be very well fitted by (1—T/T _C ) with best values=0.322(16) for⁶³NiNi, = 0.427(42) for⁶⁶CuNi, and=0.427(14) for⁶⁷ZnNi respectively. The differences between these exponents indicate that there could be probe atom dependent deviations from proportionality between hyperfine field and bulk magnetization in the critical region.Work performed in partial fulfillment of the requirements for a doctorate in physics at the Freie Universität, Berlin     

Knight shifts for short-lived β emitters in Pt

The Knight shifts K for short-lived β emitters ¹²N and ²⁷Si implanted in Pt have been measured by means of β-NMR technique. The results were K(¹²N in Pt)= +(5.8 ± 2.1)× 10^-4 and K(²⁷Si in Pt)= +(1.4 ± 0.8)× 10^-3. The spin–lattice relaxation time T₁ was measured for ¹²N in Pt. The result was T₁(¹²N in Pt, T=300 K)= 66 ± 8 ms, thus, T₁T= 20 ± 2 Ks. The present Knight shifts are in good agreement with the KKR band structure calculation with local lattice relaxation determined theoretically. This revised version was published online in August 2006 with corrections to the Cover Date.     

Quantum simulation for peak broadening in atom lithography

A grating structure with period of half of the laser wavelength generated by focusing Cr atoms with nearly resonant laser standing wave atom lens was simulated using a quantum-mechanical model.The influence of thermal atomic source on atom focusing,including the statistical distribution of the longitudinal veloc- ity and the beam divergence,was discussed.The background and full-width at half-maximum (FWHM) of atomic density peaks with v_z in Maxwell distribution and v_(x0) in Gaussian distribution increase sig- nificantly compared with ideal atoms.Collimating atoms with laser cooling is necessary to decrease the peak broadening.     

Fractal Character for Tortuous Streamtubes in Porous Media

An analytical model for fractal dimension of tortuous streamtubes in porous media is derived. The proposed fractal dimension for tortuous streamtubes in porous media is expressed as a function of porosity and scale, and there is no empirical constant in the proposed expression. The model predictions for the fractal dimension of tortuous streamtubes in porous media are in good agreement with those by the box-counting method and with the observations of other researchers.     

Characteristics in optimization of CGH for array generator

A method of simulated annealing in optimization of a computer generated holo-gram(CGH)is presented.The characteristics of energy in annealing curve are analyzed.Thecooling schedule such as giving an initial temperature,the temperature function,the numberof interactions and stopping criterion are discussed.As an example,an optimization of phaserelief kinoform,a CGH with multiple phase levels,is implemented.     

Scheme for Realizing Kerr Nonlinearity in Cavity QED

We propose a scheme for realizing the Kerr-type nonlinearity for a cavity mode. In the scheme the cavity mode interacts with a single three-level atom dispersively. Under certain conditions, the evolution of the cavity field, decoupled from the atomic degree of freedom, corresponds to the Kerr effect. The scheme can be generalized to implement cross-Kerr effect and two-qubit phase gates for two cavity modes.     

Transition for Optimal Paths in Bimodal Directed Polymers

The problem for optimal paths in bimodal directed polymers is studied. It is shown that the distribution of the thermal average position of the endpoints of the optimal paths is discontinuous below the threshold p〈pc. The origin is that there is a finite possibility that only one endpoint takes the global minimum energy for p 〈 pc. Our results suggest that the percolation threshold for directed percolation is also the critical point of the transition for the possibility that the optimal paths converge to one endpoint.     

Newtonian Forms for Dilaton Spacetimes in String Theory

We show that the Newtonian forms for the motion of particles in mechanics and for light in geometrical optics can be extend to the Gibbons-Meada and the GarfinMe-Horne dilaton spacetimes in string theory. As an example,we study the bending of the light rays, the perihelion advance of planet, and the radar echo delay in the dilaton spacetimes. The results show that the gravitational effects arising from the dilaton can be observed provided that the dilaton is large enough.     

Energy dependence for directed and elliptic flow in in termediate-energy heavy ion collisions

Differential and integrated directed flow and elliptic flow of light charged particles （z≤2） are studied systematically for semi-central （b=5 fm）¹⁹⁷ Au+197 Au collisions at incident energies from 25 to 250 MeV/nucleon by the isospin-dependent quantum molecular dynamics model. The changes of directed and elliptic flow with incident energy reflect the dynamic competition between the mean field and nucleon-nucleon collisions and also between collective rotation and expansion.     

Correction for the diffraction loss in the ultrasonic attenuation measurement in VHF range

Two silicate glasses which have different acoustic properties and different thickness, were taken as the specimens, their frequency dependences of the longitudinal attenuation coefficients were measured in the frequency range of 50 to 300 MHz by the pulse reflection method, and the diffraction loss included in the measurement was corrected by theoretical calculation using A. O. Williams' expression. It has been shown that the measurement error of attenuation coefficient due to diffraction loss could be corrected very well by this method, regardless of the thickness of specimens.     

Coupled Optical Solitons for Pulse Propagation in Multi-Level Media

We investigate the shape-preserving propagation of N optical pulses in an （N ＋ 1）-level medium. We solve Maxwell-Schroedinger equations exactly and provide several types of explicit coupled soliton solutions, which are temporally amplitude- and group-velocity-matched multi-mode slow-optical pulses of the system.     

Quantum Mechanics Helps in Learning for More Intelligent Robots

A learning algorithm based on the state superposition principle is presented. The theoretical analysis shows that the needed fundamental transformations to realize this algorithm are the same as those needed in the Grover algorithm and are within current state-of-the-art technology. The simulated experiment shows that the quantum learning algorithm can help robots to learn faster and to become more intelligent.     

The Scheme for X-ray Emission Enhancement in Groove Target

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Power Consideration for Pulsed Discharges in Potassium Seeded Argon

Minimization of energy consumed in plasma generation is critical for applications, in which a large volume of plasmas is needed. We suggest that a high electron density atmospheric pressure plasmas can be generated by pulsed discharges in potassium seeded argon at an elevated temperature with a very small power input. The ionization efficiency and power budget of pulsed discharges in such plasmas are analytically studied. The results show that ionization efficiency of argon, especially at small reduced electric field E/N （the ratio of the electric field to the gas number density）, is improved effectively in the presence of small amount of potassium additives. Power input of pulsed discharge to sustain a prescribed average level of ionization in potassium seeded argon is three orders of magnitude lower than that in pure argon. Further, unlike in pure argon, it is found that very short high-voltage pulses with very high repetition rates are unnecessary in potassium seeded argon. A pulse with lOOns of pulse duration, 5kHz of repetition rate, and 2Td （1 Td = 1 × 10^-21 Vm^2） of E/N is enough to sustain an electron density of 10^19 m^-3 in 1 arm 1500K Ar＋0.1% K mixture, with a very small power input of about 0.08 × 10^4 W/m^3.