Different Kinds Of Forces Research Articles

To the relevant diameter of aerosol particles in the 0.1 to 1 μM transition range

Modern techniques used for particle sizing in the 0.1 to 1 μm transition range are based on different kinds of forces acting upon the particles. In a spiral centrifuge or a low pressure cascade impactor particles are exposed to mechanical forces and can be classified according to their aerodynamic diameter down to about 0.08 resp. 0.03 μm. In a differential mobility analyzer (DMA) particles are separated by electrical forces up to particle diameters of about 1 μm. Submicron particles below about 0.4 μm are often measured in diffusion batteries where particles are classified according to their diffusion coefficient. The diameter derived from the electrical mobility and from the diffusion coefficient can be combined to a common mobility diameter which is only a function of the geometrical particle dimensions. When studying particle behaviour in aerosol systems one has to be cautious in all cases where the forces acting upon the particles during the experiments differ from those ones used for their size characterization. To demonstrate this problem number size distributions of atmospheric aerosols are considered and particle deposition studies in human lungs are reported.

Necking behavior during high-speed spinning of poly(ethylene terephthalate).

The high-speed spinning of poly (ethylene terephthalate) has been carried out for take-up velocity up to 10000m/min in order to investigate necking behavior. Fiber diameter and temperature were measured along the spinline by optical methods, and spinning stress was measured after the end of thinning process. Strain rate, spinning stress and elongational viscosity were estimated from the measured data.The reduction of elongational viscosity is observed at a point where the fiber diameter is rapidly reduced, though the fiber temperature is decreased monotonously. This reduction of viscosity assigned to the onset of necking. In the case of take-up velocity of 10000 m/min, the necking begins at the fiber velocity of 288m/min at 221°C. This suggests that the necking occurs in the molten state for the ultra-high speed spinning. The necking begins at lower fiber velocity, lower stress, lower elongational viscosity and higher fiber temperature with increasing take-up velocity. This indicates that the necking is determined by the different kinds of forces along the spinline, such as spinning stress and cohesive force.

Numerical solution of forces and torques

The paper deals with the calculation of forces and torques for two-dimensional (cartesian, polar, axialsymmetric coordinates) magnetostatic (MS) and stationary eddy-current (SEC) problems solved by the computer program 'PROFI'. The numerical solution of Maxwell's equations using finite differences gives the input data for three different kinds of forces, which are caused by 1. currents, 2. change of permeability, 3. permanent magnets. The nonlinearity and the lamination of materials are taken into account. Both constant fields and fields varying sinusoidally with time are considered.

A new theory of ponderomotive forces on a Vlasov plasma

A new theory of ponderomotive forces exerted by high frequency electromagnetic waves on a Vlasov plasma is presented. The ponderomotive forces are made up of four different kinds of forces: a force on resonant particles, a ponderomotive force in a narrow sense, a force due to spatial dispersion, and a force on nonresonant particles. The dispersion relation gives rise to a cancellation between the first and a part of the fourth force. The present method is based on time reversal of the Vlasov equation.

High density self-broadening of the 253.65 nm mercury resonance line

Reflection techniques are used to study self-broadening of the 253.65 nm mercury resonance line at high vapor density (2.7 × 10 19−2.7 × 10 21 atoms-cm -3). The absorption profiles are deduced from reflectance data using a modified Kramers-Krönig analysis. Another method, based on semi-classical dispersion theory, is shown to be inadequate and is used here only in order to compare our results with previously reported values. Conclusions are stated concerning the effects of different kinds of forces, broadening rate, oscillator strength, and interatomic potential curves with the help of the available theoretical approaches for which validity ranges are discussed.

The effect of substrate analogues on the activity of cat liver urocanase

1. 1. A rapid reproducible method for the isolation of substantially pure urocanase from cat liver has been developed. 2. 2. The enzyme has a molecular weight of 127 000 and is isoclectric at pH 5.4. The K m for the urocanase-urocanate complex was 7.1 μM. No evidence could be found for a requirement for pyridoxal phosphate. The enzyme was inhibited by NH 2OH but complete activity was restored after dialysis or gel-permeation chromatography. 3. 3. Only trans-urocanic acid was a substrate for the enzyme. Imidazolylpropionic acid was an effective inhibitor of urocanase; of other analogues tested only imidazolyl-lactic acid and α-chloroimidazolylpropionic acid inhibited the enzyme, and these were much less effective. 4. 4. Possible reaction mechanisms for urocanase are considered, and a tentative picture of the urocanic acid binding site on the enzyme is developed. The contributions to the overall binding of different kinds of forces of interactions at various regions of the urocanic acid molecules are examined.