Homoleptic hexa- and penta-coordinated gallium(I) amide complexes of ruthenium and molybdenum.

Reaction of neutral olefin complexes of ruthenium and molybdenum with GaTMP (TMP = 2,2,6,6-tetramethylpiperidinyl) by substitution leads to the formation of respective five- and six-coordinated homoleptic products. [Ru(GaTMP)5] (1) and [Mo(GaTMP)6] (2) were isolated and characterized. Core structure geometries were analyzed using continuous shape measure, and the complexes were subjected to DFT calculations unveiling competing π-interactions between the transition metal center and the amido substituent with the unoccupied pπ orbitals of the gallium.

Simulated assessment of light transport through ischaemic skin flaps.

Currently, free flaps and pedicled flaps are assessed for reperfusion in postoperative care using colour, capillary refill, temperature, texture, and Doppler signal (if available). While these techniques are effective, they are prone to error due to their qualitative nature. In this research, different wavelengths of light were used to quantify the response of ischaemic tissue. The assessment provides indicators that are key to developing a point-of-care diagnostic device that is capable of observing reduced perfusion quantitatively. Detailed optical models of the layers of the skin were set up and appropriate optical properties assigned, with due consideration of melanin and haemoglobin concentration. A total of 24 models of healthy, perfused and perfusion-deprived tissue were used to assess the responses when illuminated with visible and near-infrared wavelengths of light. In addition to detailed fluence maps of photon propagation, a simple mathematical model is proposed to assess the differential propagation of photons in tissue; the optical reperfusion factor (ORF). The results show clear advantages of using light at longer wavelengths (red, near-infrared) and the inferences drawn from the simulations hold significant clinical relevance. The simulated scenarios and results consolidate the belief in a multi-wavelength, point-of-care diagnostic device, and inform its design to quantify blood flow in transplanted tissue. The modelling approach is applicable beyond the current research and can be used to investigate other medical conditions in the skin that can be mathematically represented. Through these, additional inferences and approaches to other point-of-care devices can be realised.

Spectroscopy of growing and evaporating water droplets: exploring the variation in equilibrium droplet size with relative humidity.

We demonstrate that the thermodynamic properties of a single liquid aerosol droplet can be explored through the combination of a single-beam gradient force optical trap with Raman spectroscopy. A single aqueous droplet, 2-6 microm in radius, can be trapped in air indefinitely and the response of the particle to variations in relative humidity investigated. The Raman spectrum provides a unique fingerprint of droplet composition, temperature, and size. Spontaneous Raman scattering is shown to be consistent with that from a bulk phase sample, with the shape of the OH stretching band dependent on the concentration of sodium chloride in the aqueous phase and on the polarization of the scattered light. Stimulated Raman scattering at wavelengths commensurate with whispering gallery modes is demonstrated to provide a method for determining the size of the trapped droplet with nanometer precision and with a time resolution of 1 s. The polarization dependence of the stimulated scatter is consistent with the dependence observed for the spontaneous scatter from the droplet. By characterizing the spontaneous and stimulated Raman scattering from the droplet, we demonstrate that it is possible to measure the equilibrium size and composition of an aqueous droplet with variation in relative humidity. For this benchmark study we investigate the variation in equilibrium size with relative humidity for a simple binary sodium chloride/aqueous aerosol, a typical representative inorganic/aqueous aerosol that has been studied extensively in the literature. The measured equilibrium sizes are shown to be in excellent agreement with the predictions of Köhler theory. We suggest that this approach could provide an important new strategy for characterizing the thermodynamic properties and kinetics of transformation of aerosol particles.

An investigation of the factors influencing the detection sensitivity of cavity enhanced Raman scattering for probing aqueous binary aerosol droplets.

Stimulated Raman scattering (SRS) from single aerosol droplets can be observed at extremely low laser threshold intensities at wavelengths commensurate with whispering gallery modes. Although droplet size can routinely be determined from the ensuing cavity enhanced Raman scattering (CERS) fingerprint, determining droplet composition is a considerably more challenging measurement. We present here an examination of the factors that influence and limit the detection sensitivity of CERS in quantifying the concentrations of sulfate and nitrate in water droplets, 20-50 microm in radius. In particular, we consider the variation in nitrate and sulfate SRS signal with variation in species concentration, probe laser intensity and droplet size. We illustrate that the band contour of the OH stretching band can be used as a relative measure of the internal light intensity circulating within the droplet and experimentally investigate how the threshold condition for SRS is achieved.

[Probable genetic independence of four hereditary characteristics peculiar to Mongoloid populations]. / Indépendance génétique probable de quatre particularité héréditaires caractéristiques des populations mongoles.

Several hereditary characteristics are found in Mongoloid populations (Asian and Amerindian) with a much higher frequency than in other populations. These are the mongoloid facial features, the presence of alcohol dehydrogenase beta 2, the presence of inactive mitochondrial aldehyde dehydrogenase 2, and the high rate of urinary excretion of beta aminoisobutyric acid. Analyses carried out in France and Switzerland have been made to research a possible correlation between these diverse characteristics. This correlation does not seem to exist. With regard to the excretion of beta aminoisobutyric acid, the hypothetical role of mercury in dental fillings has been checked in Caucasoid subjects. If this role is not completely excluded, it is far from being statistically significant.

Simplified determination of polycyclic aromatic hydrocarbons.

Accurate quantitative analysis for selected polycyclic aromatic hydrocarbons present on urban dust can be obtained by using a simple procedure consisting of sonic-probe extraction with cyclohexane; clean-up with Florisil((R))-XAD-4((R)), and measurement by high-resolution gas chromatography with flame-ionization detection (HRGC/FID). The analysis can be further simplified by eliminating the clean-up step if HRGC/electron-impact mass-spectrometry (MS) is available. Both the FID and MS methods give results consistent with those obtained by standard procedures. The direct HRGC/MS procedure, combined with chemical ionization, can also be applied to the determination of polycyclic organic materials present in solvent-refined coal, shale oil and crude oil.

Arm crank vs handrim wheelchair propulsion: metabolic and cardiopulmonary responses.

The handrim propulsion system of most manual wheelchairs has been shown to be inefficient and stressful to the cardiovascular and pulmonary systems. Arm crank propulsion has been suggested to reduce these stresses. In order to compare conventional handrim wheelchair propulsion to arm crank type wheelchair propulsion, 16 volunteers (9 able-bodied, 7 wheelchair-dependent) operated both wheelchairs over level tiled and carpeted test courses at 3km.hr-1. The arm crank propelled wheelchair was operated in 3 gear ratios: low, medium and high. Exercise bouts were 5 minutes in duration. During the final minute of each test, oxygen uptake (VO2), net locomotive energy cost (NLEC), pulmonary ventilation (VE) and heart rate (HR) were monitored. Subjects exhibited significantly lower magnitude of these physiologic responses during arm crank wheelchair propulsion relative to handrim wheelchair propulsion for all gear drive ratios. Average percent differences were 30% and 32% for VO2; 50% and 50% for NLEC; 27% and 34% for VE; and 16% and 19% for HR on the tiled and carpeted test surfaces, respectively. From these data we conclude that arm crank wheelchair propulsion is less strenuous than conventional handrim wheelchair propulsion and that arm crank propulsion systems should be considered as a possible means to improve wheelchair design.

Gas chromatographic-atmospheric pressure active nitrogen method for organomercury speciation in environmental samples.

Methods are presented for the determination of methylmercury in fish, water, urine, and sediments, and diorganomercury compounds in water. Two significant differences from previous methods are the use of methylene chloride extracting solvent which permits sample extracts to be concentrated to volumes as low as 0.1 mL, and use of a gas chromatograph interfaced to an atmospheric pressure active nitrogen (APAN) afterflow detector. Such a detector is very sensitive and selective for Hg at picogram levels. Thus, limits of detection were significantly enhanced.

Influence of a new impoundment on pesticide concentrations in warmwater fish, Saylorville Reservoir, Des Moines River, Iowa, 1977-78.

Samples of seven species of warmwater fish were collected above, within, and below newly impounded Saylorville Reservoir, Des Moines River, Iowa, from October 1977 to October 1978. Whole-body analyses by gas chromatography were significantly higher in river carpsucker (Carpiodes cyanazine and for the organochlorine insecticides dieldrin, p,p'-DDE, p,p'-TDE, p,p'-DDT, and heptachlor epoxide. Only the organochlorine insecticides were detected in fish tissue. Concentrations of dieldrin and heptachlor epoxide were significantly higher in river carpsucker (Carpiodes carpio) from the reservoir than in those from the river. Other species of fish showed no differences in pesticide concentration related to locality of collection.

Organochlorine insecticide concentrations in fish of the Des Moines River, Iowa, 1977-78.

Organochlorine insecticides were measured in fish of the Des Moines River, Iowa, in 1977 and 1978 to determine whether concentrations exceeded allowable levels and to compare differences among species. Significant differences in mean concentrations of dieldrin, sigma DDT, and heptachlor epoxide in whole-body samples of seven species of fish, Dorosoma cepedianum, Carpiodes carpio, Cyprinus carpio, Ictalurus punctatus, Pomoxis annularis, Micropterus salmoides, Stizostedion vitreum, could not be adequately explained by body size, position of species in the food chain, or percent body fat.

Persistence of dieldrin water and channel catfish from the Des Moines River, Iowa, 1971-73 and 1978.

This study was conducted to determine if dieldrin concentrations in water and fish of the Des Moines River, Iowa, decreased after registration of the compound was withdrawn by the Environmental Protection Agency in 1975. Mean June concentrations of dieldrin in river water decreased from 50 ppt in 1971 to 11 ppt in 1978. Average daily transport of dieldrin was 156 g in 1971 and 70 g in 1978. July levels in channel catfish muscle were 75 ppb in 1973 and 46 ppb in 1978. Dieldrin was still present in significant concentrations in the aquatic system 3 years after registration withdrawal.

Pesticides in ground water beneath irrigated farmland in Nebraska, August 1978.

During the 1978 irrigation season, 14 ground water samples were collected in the Central Platte region of Nebraska, an area known to have high nitrate-nitrogen (NO3--N) levels, and analyzed for the presence of 13 pesticide residues. Atrazine levels ranged from 0.06 microgram/liter to 3.12 microgram/liter and were correlated to NO3--N concentrations with a coefficient of r = +0.55. Nitrate-nitrogen concentrations were measured as indicators of deep percolation from irrigated lands and ranged from 17.1 mg/liter to 34.3 mg/liter. Alachlor levels ranged from less than 0.01 microgram/liter to 0.71 microgram/liter. The amounts of 2,4-D were indeterminate because of experimental problems. Levels of the herbicides silvex and EPTC were below the limits of detectability. Levels of the organochlorine insecticides endrin, gamma-BHC (lindane), dieldrin, DDT and its primary metabolite DDE, heptachlor and its primary derivative heptachlor epoxide, and methoxychlor were all below the detectable limits of 0.005-0.010 microgram/liter.

Evaluation of an interactive instructional television program in Hansens disease

The use of instructional television (ITV) is becoming increasingly common in developing continuing education programs in Hansen's disease (leprosy). This study attempted to determine if it is educationally advantageous to develop ITV material that incorporates an active learner response as compared with a conventional view-only format among a group of forty-seven profissional nurses employed at a public hospital. Results indicated a clear gain in the knowledge level of those nurses who actively assessed their own progress toward preestablished instructional goals. The study also reaffirms the need to conduct validation studies of mediabased instructional material in order to determine educational effectiveness

Analysis of various Iowa waters for selected pesticides: atrazine, DDE, and dieldrin-1974.

Atrazine, DDE, and dieldrin were extracted and concentrated from various surface, subsurface, and finished waters using the macroreticular resin method. Organic components in the concentrates from these waters were separated by gas chromatography; the amounts of the three pesticides in the waters ranged from 0.5 to 42,000 parts per trillion by weight. Every major watershed in the State of Iowa revealed some degree of pesticide contamination and seasonal variations were consistent with agricultural runoff models. Atrazine concentrations were highest of the three pesticides, a symptom of its widespread use in the corn belt. DDE also appeared in substantial quantities, providing further evidence of the persistence of DDT and its metabolites. Water from several shallow wells and finished water from many water treatment plants were also contaminated. Current treatment processes do not effectively remove these pesticides.

Adsorption of chlorinated pesticides from river water with XAD-2 resin.

Pesticides in river water at levels as low as parts per billion (10(12)), can be recovered by sorption on a column of XAD-2 resin, followed by elution with acetonitrile. Water is added to the acetonitrile and the pesticides are extracted by petroleum ether and determined by gas chromatography. The new procedure is more convenient to use than the solvent extraction procedure and gives comparable results for dieldrin.