Aspect-ratio dependent oscillatory thermocapillary convection in the floating half zone

The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to predict the onset of oscillatory thermocapillary convection.The experimental studies in the microgravity conditions on floating half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing aspect ratio,and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones of several mil...     

Non-Gravitational Effects with Density-Matching in Evaluating the Influence of Sedimentation on Colloidal Coagulation

The method of density matching between the solid and liquid phases is often adopted to effectively eliminate the effect of sedimentation of suspensions in studies on dynamic behaviour of a colloidal system. However, the associated changes in the solvent composition may bring side effects to the properties investigated and therefore might lead to a faulty conclusion if the relevant correction is not made. To illustrate the importance of this side effect, we present an example of the sedimentation influence on the coagulation rate of suspensions of 2μm （diameter） polystyrene. The liquid mixtures, in the proper proportions of water （H2O）, deuterium oxide （D2O） and methanol （MeOH） as the liquid phase, density-matched and unmatched experiments are performed. Besides the influence of viscosity, the presence of methanol in solvent media, used to enhance the sedimentation effect, causes significant changes （reduction） in rapid coagulation rates compared to that in pure water. Without the relevant corrections for those non-gravitational factors it seems that gravitational sedimentation would retard the coagulation. The magnitude of the contribution from the non-gravitational factor is quantitatively determined, making the relevant correction possible. After necessary the influence of the sedimentation on coagulation rates at corrections for all factors, our experiments show that the initial stage of the coagulation is not observable.     

Spatio-Temporal Dynamical Systems in Inner-Shell Photoionization in Free Molecules,Clusters, and Solids

Dynamic spatial hole localization and symmetry breaking phenomena are examined. Absorption of X-ray synchrotron and free-electron–laser radiation in matter is accompanied by strong dynamic corehole localization and temporary trap of the electron ejected from a deep level within the finite size potential barrier. As a result the symmetry of core excited states is reduced in comparison with ground state as the inversion symmetry is being broken. This is a very general property of coreexcited polyatomic compounds with equivalent atoms as their equivalence implies their equal probability of excitation averaged over large timescale but not simultaneous core excitation. Different approaches to rationalizing the symmetry breaking phenomena are presented and discussed with the emphasis on the quasiatomic dynamic corehole localization model. By examining the experimental ultrafast probe of photoabsorption processes we demonstrate an important role of spatio-temporal (nanometric-femtosecond) dynamically localized coreexcited moieties in molecule, clusters and solids. The photoelectron angular distributions from N and O 1s levels in fixed-in-space N₂ and CO₂ molecules, the photoelectron induced rotational heating of N₂, the Auger decay spectra of N₂ and the near S 1s edge X-ray absorption fine structure of free SF₆ molecules are discussed in more detail.     

Spin squeezing and quantum correlations

We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.