Zeolite-fiber integrated optical chemical sensors for detection of dissolved organics in water

MFI zeolite coated optical fiber sensors have been developed for in situ detection of dissolved organics in water. The sensors operate by monitoring the optical reflectivity changes caused by the selective adsorption of organic molecules, i.e., 2-propanol or pentanoic acid in this study, from aqueous solutions in the zeolitic pores. Reversible and monotonic sensor signals were observed in response to the variation of 2-propanol concentration in water with fast response. However, the sensor exhibited a much slower response to pentanoic acid than to 2-propanol. It was also found that substitution of Si by Al in the MFI framework increased the adsorption of pentanoic acid that resulted in enhanced sensor responses.     

An investigation of the solidification of a metal and two n-paraffins using an acoustic technique

A novel acoustic technique is described for following the motion of the solid-liquid interface during the freezing of mercury, n-hexadecane and n-octadecane where heat transfer is unidirectional. It is shown that the actual amount of solidification occurring in a given time differs from that predicted using a numerical solution to the transient heat conduction problem. The differences are small for mercury but large for the paraffins. They are interpreted in terms of the nature of the solid-liquid interface. Furthermore the experimental and predicted temperature distributions in the liquid and solid phases differ. These differences are extremely small for mercury. The data for the three materials conform to a relationship observed previously according to which the thickness of the solidified layer is a linear function of the square root of time. The work was carried out at the Georgia Institute of Technology.     

Well-posedness,Decay Estimates and Blow-up Theorem for the Forced NLS

In this article we prove that the following NLS iu_t = u_{zz}-g|u|^{P-1}u,g > O, x, t > 0 with either Dirichlet or Robin boundary condition at x = 0 is well-posed. L^{p + 1} decay estimates, blow-up theorem and numerical results are also given.     

Di­chloro­bis(1,2‐phenyl­enedi­amine)­nickel(II)

The title compound, [NiCl₂(C₆H₈N₂)₂], contains centrosymmetric mol­ecules with two phenyl­ene­di­amine ligands coordinated in a bidentate fashion. The Ni—N distances are 2.088 (1) and 2.096 (1) Å, and the Ni—Cl distance of 2.4635 (4) Å. The plane of each phenyl­enedi­amine mol­ecule makes a dihedral angle of 26.53 (7)° with the NiN₄ plane. Extensive hydrogen bonding leads to distinct cleavage in the bc plane.     

The combined influence of a rough surface and thin fluid film upon the splashing threshold and splash dynamics of a droplet impacting onto them

Surface roughness can have a critical effect upon the splashing threshold and dynamics of a drop impacting on either a dry or rough solid surface or one coated by a thin fluid film. As most coating applications and spray systems quickly evolve to a state where the droplets impinge upon fluid deposited by preceding droplets, the combined contributions of surface roughness and a pre-deposited thin liquid film of comparable thickness upon droplet impingement dynamics are examined. For comparison, we include results for droplets impacting on a smooth, dry surface and a smooth surface wetted by a thin fluid film. The inclusion of surface roughness considerably lowers the splashing threshold and alters the splashing dynamics such that differences in fluid surface tensions between 20.1 and 72.8 dynes/cm or viscosities between 0.4 and 3.3 cP have little effect.     

The splash/non-splash boundary upon a dry surface and thin fluid film

On the basis of empirical data, power-law boundary relations are formulated to delineate the splash and non-splash regions on dry surfaces or thin films under isothermal conditions, using the Ohnesorge and Reynolds numbers. Approximation of the relations permits cancellation of fundamental fluid physical constants to give simplified formulas which provide insight into the governing parameters describing splashing and non-splashing behaviors. Thus, for a droplet impinging upon a dry solid surface, the splash/non-splash border is well described by √Ca = 0.35. For a drop impinging upon a thin fluid film, the analytical simplification yields a boundary described by √We = 20. For both expressions, values greater than the numerical value result in splashing.     

Using RngStreams for parallel random number generation in C++ and R

The RngStreams software package provides one viable solution to the problem of creating independent random number streams for simulations in parallel processing environments. Techniques are presented for effectively using RngStreams with C++ programs that are parallelized via OpenMP or MPI. Ways to access the backbone generator from RngStreams in R through the parallel and rstream packages are also described. The ideas in the paper are illustrated with both a simple running example and a Monte Carlo integration application.