The First Droplet in a Cloud Chamber Track

In a cloud chamber, the quantum measurement problem amounts to explaining the first droplet in a charged-particle track; subsequent droplets are explained by Mott’s 1929 wave-theoretic argument about collision-induced wavefunction collimation. I formulate a mechanism for how the first droplet in a cloud chamber track arises, making no reference to quantum measurement axioms. I look specifically at tracks of charged particles emitted in the simplest slow decays, because I can reason about rather than guess the form that wave packets take. The first visible droplet occurs when a randomly occurring, barely-subcritical vapor droplet is pushed past criticality by ionization triggered by the faint wavefunction of the emitted charged particle. This is possible because potential energy incurred when an ionized vapor molecule polarizes the other molecules in a droplet can balance the excitation energy needed for the emitted charged particle to create the ion in the first place. This degeneracy is a singular condition for Coulombic scattering, leading to infinite or near-infinite ionization cross sections, and from there to an emergent Born rule in position space, but not an operator projection as in the projection postulate. Analogous mechanisms may explain canonical quantum measurement behavior in detectors such as ionization chambers, proportional counters, photomultiplier tubes or bubble chambers. This work is important because attempts to understand canonical quantum measurement behavior and its limitations have become urgent in view of worldwide investment in quantum computing and in searches for super-rare processes (e.g., proton decay).

Preparation and Characterization of Waterborne UV Lacquer Product Modified by Zinc Oxide with Flower Shape

In this paper, the waterborne UV lacquer product (WUV) was used as the main raw material, zinc oxide (ZnO) was used as the additive, and the stearic acid as the surface modifier. According to the method of spraying coating on the surface of poplar wood (Populus tomentosa), a simple and efficient preparation method was carried out to generate a super-hydrophobic surface and enhance the erosion resistance of the coating. By testing, the contact angle (CA) of water on the coating surface can reach 158.4°. The microstructure and chemical composition of the surface of coatings were studied by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The results showed that under acidic conditions, the non-polar long chain alkyl group of stearic acid vapor molecule reacted with the hydroxyl group in acetic acid, the metal ions of the ZnO were displaced to the stearic acid and generated globular zinc stearate (C36H70O4Zn). The hydrophobic groups –CH3 were grafted to the surface of zinc stearate (ZnSt2) particles and the micro/nano level of multistage flower zinc stearate coarse structure was successfully constructed on the surface of poplar wood, which endowed it with superhydrophobic properties. It is shown that the coating has good waterproof and erosion resistance.

Atmospheric chemistry of the self-reaction of HO2 radicals: stepwise mechanism versus one-step process in the presence of (H2O)n (n = 1–3) clusters

In the incorporation of the catalyst (H2O)n (n = 1–3) into the HO2 + HO2 → H2O2 + 3O2 reaction, the catalytic effect of water, water dimers and water trimers is mainly derived from the contribution of a single water vapor molecule by a stepwise route.

The catalytic effect of water, water dimers and water trimers on H2S +3O2formation by the HO2+ HS reaction under tropospheric conditions

Catalyst X (X = H2O, (H2O)2and (H2O)3) is incorporated into the channel of H2S +3O2formation and the catalytic effect of water, water dimers and water trimers is mainly taken from the contribution of a single water vapor molecule.

Combined Radiation-Evaporation Model of a Liquid Droplet Layer in Space

Assuming that the droplet layer is a uniform medium, an evaporation intensity analogous to radiation intensity was defined based on an analysis of vapor molecule transfer characteristics in the droplet layer. An evaporation transfer equation was then established, from which a one-dimensional evaporative mass flux expression was obtained and combined with the radiation heat transfer model. The combined radiation-evaporation model was used to analyze the influence of the exit temperature and the optical thickness of the droplet layer on temperature distribution, evaporation loss rate, and system lifetime. In the case of a certain droplet diameter and a small optical thickness (κD≤1), the numerical results show that temperature decreases approximately linearly with layer length. The evaporation loss rate increases as the exit temperature and optical thickness increase, and the main contribution to the evaporation loss rate comes from the high temperature portion of the liquid layer near the exit of the liquid generator, i.e., the evaporation loss rate increases rapidly in a short length of the liquid droplet layer and approaches a stable value as the length reaches a certain value. With the same working fluid mass overloading proportion of the droplet layer, the system lifetime is mainly determined by the exit temperature of the liquid droplet layer. For example, if the exit temperature decreases from 320 to 310 K, the system lifetime increases by approximately three times. However, system lifetime has a weak relationship with optical thickness.

Sub-10 nm particle growth by vapor condensation – effects of vapor molecule size and particle thermal speed

The growth of freshly formed nanoparticles has been investigated. A new analytical expression based on a recently developed exact solution for the condensational growth rate has been derived. Based on the new growth rate, a new approximate but accurate analytical expression for growth time has been derived. The expression includes transition regime effects on growth, molecule size effects on the collision cross section and particle thermal speed effects on the relative collisional speeds – the last two of which are typically neglected, but may have significant effects when dealing with the growth of freshly nucleated particles. To demonstrate the use of the derived expressions, the contribution of sulphuric acid and organic compounds on sub 3 nm and sub 10 nm particle growth rates has been studied. For sulphuric acid also the effect of hydration as function of relative humidity has been taken into account. According to the new expression the sulphuric acid concentration needed for 1 nm/h growth in sub 3 nm range is ca. 1.5×107 cm−3, which is a factor of 1.5 smaller than values typically used in aerosol physics based on standard model in kinetic regime.