Evaluation of urinary methoxyphenols as biomarkers of woodsmoke exposure

Urinary methoxyphenols have been proposed as biomarkers for woodsmoke exposure, but the relationship between exposure and urinary methoxyphenol concentrations has not been characterized. We collected personal particulate matter2.5 and urine samples from 9 adults experimentally exposed to smoke from an open wood fire to characterize this relationship. Personal exposures (PM2.5 mean 1500 microg/ m3) varied 3.5-fold. Twenty-two methoxyphenols, levoglucosan, and 17 polynuclear hydrocarbons were quantified by gas chromatography/mass spectrometry assays for personal filter samples and urine samples. Most methoxyphenols had measurable preexposure levels. Propylguaiacol, syringol, methylsyringol, ethylsyringol, and propylsyringol had peak urinary concentrations after the woodsmoke exposure. Eight subjects had peak urinary elimination of methoxyphenols within 6 h (t1/2 3-5 h), whereas one had delayed elimination. Several metrics for urinary excretion were evaluated. Analyte concentration was greatly affected by diuresis. Excretion rate and analyte concentrations normalized by creatinine gave a clearer signal and were equivalent in predictive ability. Twelve-hour average creatinine-normalized concentrations of each of the 5 methoxyphenols gave a Pearson correlation > or = 0.8 with their particle-phase concentration. The sum of urinary concentrations for the 5 methoxyphenols versus levoglucosan on personal filters gave a regression coefficient of 0.75. This sum versus PM2.5 gave a regression coefficient of 0.79. The intercept of this regression suggests that the threshold for detection of an acute exposure event would be approximately 760 microg/m3 particulate matter from woodsmoke. The signal-to-noise (12-h postexposure average/preexposure average) ranged from 1.1 to 8 for the 5 methoxyphenols. Analysis of multiple compounds provided assurance that elevations were not artifactual due to food or other products.     

Virtual reality (VR) for psychotherapy: From the physical to the social environment.

Discusses current and future therapeutic applications of virtual reality (VR). To date, treatments incorporating VR have involved the simulation of physical (as opposed to social) aspects of the environment. Researchers have produced simulations of heights, different kinds of spaces, and the experience of flying, with the goal of improving the delivery of exposure and desensitization for the treatment of phobias. Researchers are only beginning to explore simulation of the social environment. When VR gains the ability to simulate human social interaction, it can be used to assist in treating a wider variety of conditions, including social phobia, fear of intimacy, and sexual aversion. More long range goals are the use of VR for the exploration of childhood memories, overcoming maladaptive thinking, empowerment, increasing empathy, expressing emotions, developing and maintaining boundaries, and promoting marital satisfaction and bonding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elements of Particle Technology in the Chemical Industry

Difficulties are encountered sometimes with new chemical products during manufacturing, handling, or marketing due to lack of knowledge in the particle technology area. The major problem discussed in this article is that, in most cases, this is due to the neglect of the mutual interactions between different unit operations during manufacturing and conveying in the design phase of these new products. Unlike the case with most other materials, it is not sufficient to know the present thermodynamic state of bulk powdery materials in order to determine their attributes since their “history” also affects the material's properties and behavior, often dramatically. The mutual effects between different operations such as bulk material handling, conveying, milling, and drying, as well as the property changes that occur during these processes, are discussed by presenting several case studies from the authors' own work and previous experiences. These include such properties as effective thermal conductivity, size distribution, flowability, caking, and surface activation in such operations as fluidized bed drying, pneumatic conveying, granulation, and tabletting. Finally, a flow sheet containing unit operations with powders is optimized using experience gained from these case studies.     

Time-dependent density functional study of field emission from nanotubes composed of C, BN, SiC, Si, and GaN

Field emission from various types of nanotubes is studied by propagating the electronic density in real space and time using time-dependent density functional theory. Capped (5, 5) C, BN, SiC, Si, and GaN nanotubes are considered. The GaN, SiC, and Si nanotubes were found to be significantly better field emitters than C and BN nanotubes, both in terms of current magnitude and sharpness of peaks in the energy spectra. By analyzing the electronic structure of the various systems it is seen that the nanotubes with the highest currents have electron densities that extend significantly from the nanotube in the emission direction.     

The SN2 Transition State. 6: Breakdown of the Reactivity–Selectivity Principle in the SN2 Reaction of α-Halocarbonyl Compounds. A Molecular Orbital Analysis [1]

A molecular orbital (MO) analysis of the S_N2 transition state (TS) of α-carbonyl derivatives is described with various nucleophile leaving group pairs. On the basis of this analysis it is shown that the enhanced selectivity toward nucleophiles observed in α-halocarbonyl compounds is directly associated with S_N2 rate enhancement. Both observations result from a stabilizing frontier orbital interaction between a high lying π-type three center orbital along the reaction coordinate axis and the carbonyl π-system. The magnitude of interaction is greater for more powerful nucleophiles, resulting in both greater reactivity as well as additional selectivity relative to simple alkyl halides.     

Oxidative damage to DNA in plaques of MS brains

To a number of nurse educators, the Internet is a new, innovative and exciting teaching and learning tool. Sadly, anecdotal evidence suggests that many educators remain largely unaware of these new technologies or their potential to assist in the process of learning. Such a situation is not surprising given the limited amount of literature detailing the use of the Internet in nurse education and a profound lack of educational research in the area. This paper will highlight some of the benefits of the Internet for nursing students and educators, provide an overview of a number of Internet technologies and suggest some practical applications of these technologies in nurse education. A glossary of Internet terms is included.