Surface-enhanced infrared ellipsometry of self-assembled undecanethiol and dodecanethiol monolayers on disordered gold nanoisland substrates.

Infrared spectroscopic ellipsometry (IRSE) is a powerful optical probe of various chemical and physical properties of molecules adsorbed onto solid surfaces. In particular, IRSE can be useful for detecting adsorption-induced changes in the IR spectra of self-assembled monolayers (SAMs), and unlike traditional IR absorption spectroscopies, IRSE provides useful information about the phase of the reflected radiation from the SAMs. However, in the standard IRSE experimental geometry using flat substrates for SAMs, the detectable signal containing these phase data is considerably weaker than the corresponding absorbance data. In our present work, we demonstrate that enhancing the local optical fields at the sample surface through the use of a disordered Au nanoisland substrate can substantially increase both these absorbance and phase signals. We also demonstrate how this surface-enhanced infrared spectroscopic ellipsometry (SEIRSE) can be utilized for straightforward analysis of absorption peak widths, as well as to obtain information about the orientation of the terminal methyl on adsorbed SAMs. As model SAMs for this study, we use undecanethiol (UDT) containing 10 CH(2) units and a terminal CH(3) group, as well as dodecanethiol (DDT) containing 11 CH(2) units with its terminal CH(3) at a different orientation than UDT. We show that surface-enhanced IRSE is sensitive to subtle vibrational signatures of the differently oriented terminal methyls of these two homologous alkanethiol SAMs.

Retrospective analysis of calls to poison control centers resulting from exposure to the insect repellent N,N-diethyl-m-toluamide (DEET) from 1985-1989.

This study analyzed 9,086 human exposures involving N,N-diethyl-m-toluamide--containing insect repellents that were reported to Poison Control Centers from 1985-1989. Nearly two-thirds of those exposed had no adverse effects or only experienced minor symptoms that resolved rapidly. Symptoms were more likely to occur after ocular or inhalation exposures and least likely to occur if the product was ingested. The only reported death occurred in a patient who suicidally ingested 8 oz of an insect repellent containing N,N-diethyl-m-toluamide. Five patients may have experienced a serious or potentially life-threatening effect but the poison center record did not provide unequivocal substantiation of the effect or clearly establish N,N-diethyl-m-toluamide as the causative agent. From the analysis of those patients calling Poison Control Centers, it appears the risk of serious medical effects with the labeled use of N,N-diethyl-m-toluamide-containing insect repellents is low in comparison with its reported annual use by about 30% of Americans. For patients contacting Poison Control Centers, the occurrence of adverse effects appears to be related to the route of exposure rather than age or gender of the patient or the concentration of N,N-diethyl-m-toluamide in the product.

A prospective, population-based study of acute ibuprofen overdose: complications are rare and routine serum levels not warranted.

The availability of ibuprofen without a prescription requires assessment of its acute toxicity in the general population. We report results from a prospective study of 329 cases of ibuprofen overdose from a statewide cohort that were reported to our poison center between April 1985 and November 1986; 85 patients had ibuprofen serum concentrations measured. Gastrointestinal disturbances and central nervous system depression were the most common clinical findings (42% and 30% of patients, respectively), but the severity was mild; only one patient had severe symptoms that could be attributed to ibuprofen. Ibuprofen serum concentrations correlated poorly with gastrointestinal symptoms (r = -.177), central nervous system findings (r = .176), presence of coingestants (r = .078), and presence of potentially life-threatening symptoms (r = .087). We evaluated the usefulness of a previously published nomogram to predict ibuprofen toxicity; the positive predictive value for severe symptoms was 6% for all patients and 0% for patients ingesting ibuprofen alone. We conclude that the frequency of life-threatening complications from ibuprofen overdose is low, the nomogram is not predictive of toxicity, and routine serum concentration determinations are not useful as an adjunct in the management of overdose cases.

Age-related decrements in Stroop Color Test performance.

Administered a modified Stroop Color-Word Test to 80 healthy males aged 21-90 years as part of a study of neuropsychological functioning. No age differences were demonstrated on simple reading tasks; however, significant age effects were observed for the color naming and interference tasks (ps less than .001). Ss in the oldest age groups (61-70 and 71-90 years) performed more slowly than younger individuals on both of these. Of a variety of tests administered, performance on the Stroop Test was most affected by age. Because impairment on Stroop color naming and interference tests appears to be a concomitant of normal aging, caution should be exercised when one is interpreting Stroop test results from older patients with suspected cerebral dysfunction.

Aerobic exercise training and improved neuropsychological function of older individuals.

The effects of a four month aerobic exercise conditioning program on neuropsychological test performance, depression indices, sensory thresholds, and visual acuity of 55-70 year old sedentary individuals were evaluated. Aerobically trained subjects were compared with two age-matched control groups of subjects: those who trained with strength and flexibility exercises and others who were not engaged in a supervised exercise program. The aerobically trained subjects demonstrated significantly greater improvement on the neuropsychological test battery than did either control group. Depression scores, sensory thresholds, and visual acuity were not changed by aerobic exercise. The pattern of results suggests that the effect of aerobic exercise training was on central rather than on peripheral function. We speculate that aerobic exercise promoted increased cerebral metabolic activity with a resultant improvement in neuropsychological test scores.

The volume of a swallow: correlation of deglutition with patient and container parameters.

The study purpose was to evaluate the relationships between average volume of a swallow (AVS) and age, height, weight, sex, and container-opening diameter (COD) to confirm and expand the work of Jones and Work. Forty-five males and 50 females between two and 18 years of age were studied. Each subject drank five swallows from each of four containers. AVS for each subject under each condition was calculated and the joint relationship with the independent variables analyzed by multiple regression. Age, height, and weight were highly intercorrelated, and each had similar correlations with AVS. COD was important; between 24 and 90 months of age, swallows from the 6.5 cm COD had a three- or four-fold larger AVS than swallows from the 1.5 cm COD. Sex differences in AVS were noted in subjects over seven years of age. These findings suggest that determination of the child's age and number of swallows ingested may be useful in estimating the fluid volume ingested and the potential toxicity of an exposure.

Line bisection and unilateral visual neglect in patients with neurologic impairment.

Unilateral visual neglect is a common symptom or sign in patients with lesions of the nondominant hemisphere. Several techniques have been used to demonstrate visual neglect. One such technique--asking a patient to bisect a horizontal line and expecting an estimate of center away from the side neglected--has been used for over 70 years but has not been statistically evaluated. We conducted a formal evaluation of this method and found that under special conditions, line-bisection performance can discriminate between patients with right-hemisphere lesions and patients with diffuse lesions, patients with left-hemisphere lesions, and hospital controls. When used to investigate visual neglect in an individual patient, the line-bisection test should be given in conjunction with other complementary procedures such as symmetric drawings and the Memory-for-Designs Test.

Application of combined liquid chromatography/mass spectrometry (LC/MS): analysis of petroporphyrins and meibomian gland waxes.

Application of the moving belt LC/MS interface is illustrated by two diverse examples, one from the field of petroporphyrin chemistry, the other, a sample of high molecular weight waxes from the steer meibomian gland (eye). Petroporphyrins are difficult of convert to derivatives suitable for GC analysis and the advantages of analysis by a combined separation/identification method are well demonstrated by the LC/MS runs. High molecular weight waxes can be saponified and derivatized for other analyses such as GC and GC/MS, but information regarding the distribution of alcohol and acid in the combined state is destroyed. This study shows that such information can be obtained by a combined LC/MS analysis without chemical manipulation of the sample.