Numerical Characterization of Particle Beam Collimation: Part II Integrated Aerodynamic-Lens–Nozzle System

As a sequel to our previous effort on the modeling of particle motion through a single lens or nozzle, flows of gas–particle suspensions through an integrated aerodynamic-lens–nozzle inlet have been investigated numerically. It is found that the inlet transmission efficiency (η_t) is unity for particles of intermediate diameters (D_p ～ 30–500 nm). The transmission efficiency gradually diminishes to ～40% for large particles (D_p > 2500 nm) because of impact losses on the surface of the first lens. There is a catastrophic reduction of η_t to almost zero for very small particles (D_p ≤ 15 nm) because these particles faithfully follow the final gas expansion. We found that, for very small particles, particle transmission is mainly controlled by nozzle geometry and operating conditions. A lower upstream pressure or a small inlet can be used to improve transmission of very small particles, but at the expense of sampling rate, or vice versa. Brownian motion exacerbates the catastrophic reduction in η_t for small particles; we found that the overall particle transmission efficiency can be roughly calculated as the product of the aerodynamic and the purely Brownian efficiencies. For particles of intermediate diameters, Brownian motion is irrelevant, and the modeling results show that the transmission efficiency is mainly controlled by the lenses. Results for an isolated lens or nozzle are used to provide guidance for the design of alternative inlets. Several examples are given, in which it is shown that one can configure the inlet to preferentially sample large particles (with η_t > 50% for D_p = 50–2000 nm) or ultrafine particles (with η_t > 50% for D_p = 20–1000 nm). Some of the results have been compared with experimental data, and reasonable agreement has been demonstrated.     

Identification of cheese mite species inoculated on Mimolette and Milbenkase cheese through cryogenic scanning electron microscopy

Samples of Mimolette (France) and Milbenkase (Germany) cheeses traditionally ripened by mites were analyzed to determine the mite species present on each sample. Scientific literature was reviewed to understand which mite species most commonly infest cheese. Morphological features possessed by mites were then studied to understand what unique characteristics are required to ensure accurate identification. After identification and compilation of a detailed key of stored food mites (subclass Acari, order Astigmata) and their delineating features, the mites were viewed through a cryogenic scanning electron microscope. It was determined that Mimolette cheese is inoculated with Acarus siro L. The features studied to identify this mite species included idiosomal length and shape, setae length and arrangement, leg size, placement of anus and genitals, and solenidia shape. The Milbenkase cheese is inoculated with Tyrolichus casei Oudemans, which was evident after viewing the same features used to identify A. siro and the supracoxal seta shape. With this knowledge, further research can be conducted on the 2 cheese varieties to understand what chemical, physical, and microbial changes occur within the cheeses because of mites. It is important to identify the mite species present on each cheese variety to improve our understanding of their role in creating the distinctive characteristics that set these cheeses apart from others.     

Construction of a Microcomputer Controlled Photoacoustic Spectrometer

ABSTRACT

We have developed a UV-Visible photoacoustic spectrophotometer using relatively inexpensive individual optical components. The instrument was initially developed due to the absence of a commercial photoacoustic instrument in the UV-Visible range. We have found that this custom built instrument allows numerous software generated options that are unavailable on any commercial spectrometric instruments. In addition to recording routine intensity versus wavelength spectra, we can record the following: 1) resolution of the spectra in layered samples; 2) quantitative depth profiles in samples; 3) spectra and spectral fragments can be smoothed and joined into continuous spectra; and 4) signal averaging of spectra can be carried out. The construction of this custom built instrument allowed the maximum flexibility in experimental application with minimum cost to the investigator.     

Effect of humidity on the thermal conductivity of porous zirconia ceramics

This study focuses on the role of the water content on the effective thermal conductivity of porous ceramics placed in different conditions of relative humidity. Fully stabilized zirconia samples with variation in the capacity to take up water were prepared by varying the temperature of the thermal treatment. The pore volume fraction of the dried samples decreases from 56% down to 30%. Thermal conductivity measurements were made on samples placed in a chamber where the relative humidity was fixed between 3% and 99%. For all samples, the experimental values of the effective thermal conductivity increase significantly with the water content. Experimental results agree closely to analytical predictions based on the upper limit of the Hashin and Shtrikman expressions for calculating the thermal conductivity of the pores (constituted by air and water) and Landauer's effective medium expression for calculating the effective thermal conductivity of the material.     

Two new measures of attitudes about the acceptability of teen dating aggression.

Aggression in dating relationships is associated with attitudes that justify its use. Attitudes about dating aggression are targeted by prevention efforts, contributing to a need to measure these attitudes sensitively, accurately, and multidimensionally. We describe two new measures of attitudes about aggression, each tapping different attitudinal components, and compare their psychometric properties with an existing scale. The 1st assesses attitudes about physical aggression in provocative situations. The 2nd taps attitudes about verbally aggressive, controlling, and jealous tactics against a dating partner. Data from 2,313 high school students were factor analyzed and cross-validated for each new scale. Compared with an existing measure, the scales had comparable levels of reliability and validity and improved response distributions. A 2nd-order factor analysis lends support to a multidimensional view of attitudes about dating aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)