Ecotoxicological evaluation of three deicers (NaCl, NaFo, CMA)-effect on terrestrial organisms.

The use of chemical deicers such as sodium chloride (NaCl) has increased significantly during the past three decades. Deicers induce metal corrosion and alter the physicochemical properties of soils and water. Environmental damage caused by the use of NaCl has prompted government agencies to find alternative deicers. This article presents a comparative ecotoxicological study of three deicers on soil organisms. Sodium formiate (NaFo) and calcium-magnesium acetate (CMA) are the most interesting commercially available deicers based upon their characteristics and potential toxicity. Organisms used in this study were four species of macrophytes (cress (Lepidium sativum), barley (Ordeum vulgare), red fescue grass (Festuca rubra), Kentucky bluegrass (Poa pratensis)) and an invertebrate (Eisenia fetida). Using standardized and modified methods, the relative toxicity of deicers was CMA < NaFo congruent with NaCl. The results demonstrate that these chemicals could have similar impacts in terrestrial environments since similar quantities of NaFo and greater amounts of CMA are necessary to achieve the same efficiency as NaCl. The toxicity of the tested substances was lower in natural composted soil than in artificial substrate (silica or OECD soil), indicating decreased environmental bioavailability. The response of the organisms changed according to endpoint, species, and soil characteristics (artificial substrate as compared to natural organic soil). The most sensitive endpoint measured was macrophyte growth with Kentucky bluegrass being the most sensitive species.

Splenic injury: trends in evaluation and management.

BACKGROUND: Changing methods of evaluating blunt abdominal trauma and expanding selection criteria for nonoperative management (NOM) of splenic injury can increase the number of patients managed nonoperatively without affecting success rates. METHODS: The charts of 164 patients with blunt splenic injuries from July 1, 1991, to June 30, 1996, were reviewed. Thirty-eight patients were excluded because of immediate laparotomy without adjunctive tests or expiration in the resuscitative period. Injuries were graded according to the Organ Injury Scale. RESULTS: Overall, successful NOM occurred in 84% of patients (73 of 87). NOM was successful in 5 of 7 patients > 55 years old and in 14 of 15 patients with Glasgow Coma Scale scores < 13. CONCLUSION: Use of computed tomography increased NOM of splenic trauma from 11 to 71% during the 5-year period for injuries of equivalent severity. Age > 55 years or abnormal neurologic status should not preclude NOM, because success was related only to injury grade.

Trends in the management of hepatic injury.

BACKGROUND: Options for management of blunt hepatic injury have broadened to include both operative management (OM) and nonoperative management (NOM). We identify trends in evaluation and management of blunt hepatic injury at a level 1 trauma center. METHODS: Charts of 106 patients with blunt hepatic injuries from July 1, 1991 to June 30, 1995 were reviewed for method of abdominal evaluation (computed tomography versus DPL), injury severity score, liver injury grade, method of management, length of stay (LOS), transfusion requirements, complications, and outcome. RESULTS: Nonoperative management steadily increased to 86%. Successful NOM occurred in 96% (48 of 50) and was not related to injury grade. Transfusion requirements were significantly greater in the group with OM versus those with NOM (11.3 versus 2.7). Patients with NOM also had significantly shorter intensive care unit stay and total LOS. CONCLUSIONS: The majority of patients with blunt liver injury can be successfully managed nonoperatively regardless of injury grade. Nonoperative management may allow decreased resource utilization because of shorter hospital stays and decreased transfusion requirements.

Extra-axial stigmatic imagery with a thick planar kinoform.

A kinoform lens and its substrate are usually treated as two distinct components with a common interface. Thick kinoform lenses treat the relief profile and the substrate as an integrated component. An analytical approach for the design of higher-order thick kinoform lenses for stigmatic imaging between extra-axial conjugate points is presented. An illustrative example is given.

A miniaturized Ames mutagenicity assay employing bioluminescent strains of Salmonella typhimurium.

Increased awareness of the role of environmental factors in carcinogenesis has led to an emphasis on preventing or minimizing exposure to genotoxicants. This is presently promoting the development of simple, rapid, cost-effective mutagenicity screening assays. We have developed a test system based on the well-known Salmonella mutagenicity assay. The lux genes, which permit cells to emit light through bioluminescence, were introduced into Salmonella typhimurium strain TA98. These bacteria were exposed for 48 h to chemicals or complex mixtures in 48-well microplates containing an appropriate liquid medium. Cells were subsequently centrifuged and resuspended in buffer. The final postexposure revertant biomass was then estimated using a microluminometer. Replication trials confirmed methodological reproducibility. Clear dose-response relationships were obtained with the direct frameshift mutagens 4NQO and 2NF. Mutagenicity threshold effect concentrations found for these compounds were comparable to those reported in the literature. Industrial effluents and environmental extracts (effluents, suspended solids) were also tested and results compared well with those of the SOS Chromotest. While further validation of this new adaptation of the Ames test will be required, it appears at this time that it could be well suited for routine screening of xenobiotics and environmental samples.

Curved kinoform lenses for stigmatic imaging of axial objects.

We present a generalized approach for determination of the location of full-period zones and the surface-relief profile of a spherically curved kinoform lens that provides stigmatic imaging between any two prespecified points on axis. A common framework is provided for the treatment of both converging and diverging kinoform lenses. Some illustrative numerical results demonstrate the convenient amenability of our method in practical applications.

Image digitizing in conventional radiology.

Since early 1991 a new procedure has been tested at the Hôpital du St-Sacrement that uses a phosphorous plate instead of a standard x-ray cassette. The phosphorous plate is exposed to x-rays using standard equipment and is then read by a computer that transfers the resulting image onto either a plate or a cathode screen. This new technology lends importance to the radiology technician's role in image manipulation and determination of the ideal sensitometric curve for each x-ray examination. The technician can generate an image with adjustments in latitude and contrast, depending on the radiologist's needs and notwithstanding the technical parameter settings used during the x-rays.

Fizeau digital interferometry with a diffraction-generated spherical wave for testing focusing optics.

A sufficiently small, reflective spherical particle at the focus of a test lens can replace the spherical autostigmatizing mirror in Fizeau digital interferometry, which is used for testing focusing optics. This small particle serves as a secondary coherent point source in the test arm and generates by diffraction a spherical wave that is used to produce the test beam. The relationships between the diffraction-generated wave and the size and shape of the diffracting element are discussed and also used to properly select the diffracting element. Experimental results confirm that the new technique has high accuracy.

Spectral modulation of two coherently separated femtosecond laser pulses.

A train of 150-fs 76-MHz pulses is directed into a Michelson interferometer with a path difference larger than the pulse spatial length. A modulated spectrum with a modulation frequency that increases with the path difference is observed. The consequence is discussed.

Power-transfer effects in monomode optical nonlinear waveguiding structures.

We describe power-transfer effects, over a certain threshold, among constituents of planar waveguiding structures consisting of an optical linear layer deposited onto a nonlinear substrate (CdS(x)Se(1-x)-doped glass). Proper selection of the thickness of the linear waveguiding film and the refractive index of the linear cladding allows one to obtain optical transistor action and to construct all-optical AND, OR, NOT, and XOR logic gates. The effects appear for the TE(0) guided mode.

Optical branching effect in Ti:LiNbO3 waveguides: near-field pattern studies.

The paper presents a detailed study of a single optical beam splitting into several beams (the branching effect) in photorefractive sensitive Ti:LiNbO3 optical slab waveguides. The near-field patterns of the multibeam structures are presented for different values of optical power coupled into TE guided modes of different orders. The process of partial recovery of the optically damaged waveguide (the partial shrinking of the multibeam bundle created) is also described.