Laser induced breakdown spectroscopy as a tool for discrimination of glass for forensic applications.

Materials analysis and characterization can provide important information as evidence in legal proceedings. The potential of laser induced breakdown spectroscopy (LIBS) for the discrimination of glass fragments for forensic applications is presented here. The proposed method is based on the fact that glass materials can be characterized by their unique spectral fingerprint. Taking advantage of the multielement detection capability and minimal to no sample preparation of LIBS, we compared glass spectra from car windows using linear and rank correlation methods. Linear correlation combined with the use of a spectral mask, which eliminates some high-intensity emission lines from the major elements present in glass, provides effective identification and discrimination at a 95% confidence level.

Lifetime measurements of several S, P, and D states of thallium in a glow discharge by single-step and two-step laser-excited fluorescence.

The lifetimes of several states in a thallium see-through hollow cathode discharge, or galvatron, are obtained to characterize its potential as an atomic line filter. The lifetimes of the thallium 6(2)D(3/2), 6(2)D(5/2), and 7(2)S(1/2) states are measured by time-resolved single-step laser-excited fluorescence by use of a 276.787 nm laser pulse or a 535.046 nm laser pulse and measuring the resulting fluorescence waveform at the appropriate wavelength. Values of 6.4 +/- 0.1, 7.5 +/- 1.1, and 7.7 +/- 0.2 ns were obtained for the 6(2)D(3/2), 6(2)D(5/2), and 7(2)S(1/2) states, respectively, which agree with values obtained by previous authors, as well as calculated values. No current dependence was observed for each of these states. The lifetime of the long-lived thallium 6(2)P(3/2) degrees metastable state was measured by two-step laser-excited fluorescence at various applied currents. The metastable level was pumped by a 276.787 nm laser pulse, and a temporally delayed 535.046 nm laser pulse interrogated the population of the metastable state. Relating the fluorescence intensity to the population of the metastable state as a function of delay time yielded a decay curve for the 6(2)P(3/2) degrees metastable state. Values of 2.1 +/- 0.2, 2.8 +/- 0.1, 3.1 +/- 0.3, 3.8 +/- 0.4, and 4.8 +/- 0.6 micros were found for applied currents of 14.0, 12.0, 10.0, 8.0, and 6.0 mA, respectively. The resulting lifetimes for the 6(2)P(3/2) degrees metastable state clearly show a dependence on the applied current and are expected to be due to collisions with the wall of the cathode, as well as a contribution due to collisions with electrons.

Model-based identification of PEEP titrations during different volemic levels.

A cardiovascular system (CVS) model has previously been validated in simulated cardiac and circulatory disease states. It has also been shown to accurately capture all main hemodynamic trends in a porcine model of pulmonary embolism. In this research, a slightly extended CVS model and parameter identification process are presented and validated in a porcine experiment of positive end-expiratory pressure (PEEP) titrations at different volemic levels. The model is extended to more physiologically represent the separation of venous and arterial circulation. Errors for the identified model are within 5% when re-simulated and compared to clinical data. All identified parameter trends match clinically expected changes. This work represents another clinical validation of the underlying fundamental CVS model, and the methods and approach of using them for cardiovascular diagnosis in critical care.

Prediction of hemodynamic changes towards PEEP titrations at different volemic levels using a minimal cardiovascular model.

A cardiovascular system model and parameter identification method have previously been validated for porcine experiments of induced pulmonary embolism and positive end-expiratory pressure (PEEP) titrations, accurately tracking all the main hemodynamic trends. In this research, the model and parameter identification process are further validated by predicting the effect of intervention. An overall population-specific rule linking specific model parameters to increases in PEEP is formulated to predict the hemodynamic effects on arterial pressure, pulmonary artery pressure and stroke volume. Hemodynamic changes are predicted for an increase from 0 to 10 cm H(2)O with median absolute percentage errors less than 7% (systolic pressures) and 13% (stroke volume). For an increase from 10 to 20 cm H(2)O median absolute percentage errors are less than 11% (systolic pressures) and 17% (stroke volume). These results validate the general applicability of such a rule, which is not pig-specific, but holds over for all analyzed pigs. This rule enables physiological simulation and prediction of patient response. Overall, the prediction accuracy achieved represents a further clinical validation of these models, methods and overall approach to cardiovascular diagnosis and therapy guidance.

The application of microbore UPLC/oa-TOF-MS and 1H NMR spectroscopy to the metabonomic analysis of rat urine following the intravenous administration of pravastatin.

The metabonomic effects of hepatotoxic doses of pravastatin on the urinary metabolic profiles of female rats have been investigated using ultra performance liquid chromatography (UPLC)-oa-TOF-MS and, independently, by (1)H NMR spectroscopy. UPLC was performed using a 1 mm microbore column packed with 1.7 microm particles. Examination of the data obtained from the individual animals, aided by statistical interpretation of the data, made it possible to identify potential markers for toxicological effects, with both NMR and UPLC-MS analysis highlighting distinct changes in the urinary metabolite profiles. These markers, which included elevated taurine and creatine, as well as bile acids, were consistent with hepatotoxicity in some animals, and this hypothesis was supported by histopathological and clinical chemistry findings. The analytical data from both techniques could be used to define a metabolic "trajectory" as toxicity developed and to provide an explanation for the lack of hepatotoxicity for one of the animals. The two analytical approaches (UPLC-MS and NMR) were found to be complementary whilst the use of a 1mm i.d. x 100 mm column reduced the amount of sample required for analysis to 2 microL, compared with 10 microL for a 2.1mm i.d. x 100 mm column. The 1mm i.d. column also provided increased signal-to-noise without loss of chromatographic efficiency.

An automated method for measuring static pressure-volume curves of the respiratory system and its application in healthy lungs and after lung damage by oleic acid infusion.

Elastic pressure/volume (PV) curves of the respiratory system have attracted increasing interest, because they may be helpful to optimize ventilator settings in patients undergoing mechanical ventilation. Clinically applicable methods need to be fast, use routinely available equipment, draw the inspiratory and expiratory PV curve limbs, separate the resistive and viscoelastic properties of the respiratory system from the elastic properties, and provide reproducible measurements. This paper presents a computer-controlled method for rapid measurements of static PV curves using a long inflation-deflation with pauses, and its evaluation in six pigs before and after lung damage caused by oleic acid. The method is fast, i.e. 20.5 +/- 1.9 s (mean +/- SD) in healthy lungs and 17.7 +/- 4.1 s in diseased lungs, this including inspiratory and expiratory pauses of 1.1 s duration. In addition the only equipment used was a clinical ventilator and a PC. For healthy and damaged lungs expiratory PV curve limbs were very reproducible and were at higher volume than the inspiratory limbs, indicating hysteresis. For damaged lungs inspiratory PV limbs were reproducible. For healthy lungs the inspiratory limbs were reproducible but only after the first inflation-deflation. It is possible that during the first inflation alveoli are recruited which are not derecruited on deflation, shifting the inspiratory limb of the PV curve. The paused long inflation-deflation technique provides a quick, automated measurement of static PV curves on both inspiratory and expiratory limbs using routinely available equipment in the intensive care unit.

Effects of Hermetic Storage on Adult Sitophilus oryzae L. (Coleoptera: Curculionidae) Acoustic Activity Patterns and Mortality.

Hermetic storage is of interest to farmers and warehouse managers as a method to control insect pests in small storage facilities. To develop improved understanding of effects of hermetic storage on insect pest activity and mortality over time, oxygen levels, acoustic signals, and observations of visual movement were recorded from replicates of 25, 50, and 100 adult Sitophilus oryzae (L.) (Coleoptera: Curculionidae) hermetically sealed in 500- and 1,000-ml glass jars. Recordings were done for 28 d; twice daily for the first 6 d and twice weekly thereafter. Insect sounds were analyzed as short bursts (trains) of impulses with spectra that matched average spectra (profiles) of previously verified insect sound impulses. Oxygen consumption was highest in treatments of 100 insects/500-ml jar and lowest in 25/1000-ml jars. The rates of bursts per insect, number of impulses per burst, and rates of burst impulses per insect decreased as the residual oxygen levels decreased in each treatment. Activity rates <0.02 bursts s-1, the acoustic detection threshold, typically occurred as oxygen fell below 5%. Mortality was observed at 2% levels. The time to obtain these levels of insect activity and oxygen depletion ranged from 3-14 d depending on initial infestation levels. Acoustic detection made it possible to estimate the duration required for reduction of insect activity to levels resulting in negligible damage to the stored product under hermetic conditions. Such information is of value to farmers and warehouse managers attempting to reduce pest damage in stored crops.

Therapy for osteosarcoma in dogs with intravenous injection of liposome-encapsulated muramyl tripeptide.

Canine osteosarcoma is a spontaneous malignancy in dogs, characterized by micrometastasis to pulmonary and extrapulmonary tissues at the time of diagnosis. Standard treatment involves amputation of the affected leg, but median survival time is 3-4 months with death due to metastasis. A randomized double-blind trial was conducted to evaluate liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (liposome/MTP-PE) as a treatment for metastasis in dogs undergoing amputation for osteosarcoma. Fourteen dogs were treated with liposome/MTP-PE, and 13 were treated with empty liposomes. Median survival time was 222 days for dogs treated with liposome/MTP-PE, compared to 77 days for dogs treated with empty liposomes (P less than .002). In the liposome/MTP-PE-treated group there were still four dogs alive and free of metastasis at greater than 1 year post surgery. Treatment was well tolerated; no significant toxic effects were noted except for mild elevations in body temperature (1-2 degrees C) for 2-6 hours post injection.

Delayed sequelae after acute overdoses or poisonings: cranial neuropathy related to ethylene glycol ingestion.

A 31-year-old woman came to the hospital with breathlessness, confusion, and a refractory anion gap metabolic acidosis; acute renal failure subsequently developed. Her blood ethylene glycol concentration was 390 mg/L, and she was treated with an intravenous ethanol infusion and hemodialysis. During the tenth and eleventh day after admission bilateral seventh cranial nerve paralysis developed, as well as bilateral dysfunction of cranial nerves II, V, VIII, IX, X and XII. Magnetic resonance imaging of her head showed gadolinium enhancement of the fifth cranial nerve bilaterally and a communicating hydrocephalus. Over the subsequent 11 months she recovered full function of her cranial nerves V, VII, IX, X, and XII, and she had subjective clinical improvement to baseline function in cranial nerves II and VIII. This case serves to introduce a discussion of agents that cause delayed complications after their acute toxic ingestion.

Estimating the severity of osteoarthritis with magnetic resonance spectroscopy.

This study explores the possibility of estimating the severity of osteoarthritis in the elderly through magnetic resonance measurements of proton relaxation times in articular cartilage. Twenty-five paired samples were cut from eight cartilage specimens. The specimens had been taken in the normal course of knee surgery from patients aged 60 years or older. The reciprocal of the T1 relaxation time (1/T1) was found to have a negative association with the histological-histochemical grade of the severity of osteoarthritis. A revised, weighted version of the Mankin-Dorfman severity scale yielded stronger correlations with 1/T1 and with percent water. A nonlinear regression equation expressing osteoarthritis as a function of 1/T1 explained 38% of the variation in the severity of osteoarthritis as measured by the new scale. A superior methodology for estimating the severity of osteoarthritis on the basis of contour maps of the magnetic resonance response is suggested.

Serum creatine kinase and CK-MB isoenzyme responses to acute and prolonged swimming in trained athletes.

Six highly-trained male swimmers completed a maximum work capacity tethered swim and a 1-h continuous tethered swim at approximately 70% VO2max in order to evaluate total serum creatine kinase and CK-MB isoenzyme changes. Venous blood obtained before, 5 min post-, 6 h post-, and 24 h post-exercise was analyzed for total serum CK (kinetic UV method, normal = less than 100 U/l) and CK-MB isoenzyme (quantitative electrophoretic technique, normal = less than 5 U/l). VO2max averaged 4.59 +/- 0.28 l/min, with a mean total work time of 24.5 min to achieve maximum capacity. Mean resting total CK was 100.5 +/- 15.8 U/l. Compared to rest, neither swim bout produced a significant (p greater than 0.05) elevation in mean total creatine kinase. No CK-MB isoenzyme was observed in any post-exercise blood sample. Swimming, performed by highly-trained swimmers at high levels of intensity or for prolonged durations, may not impose sufficient degrees of trauma producing muscular stress. Therefore, the structural integrity of the cell membrane is maintained and the loss of intracellular creatine kinase to the bloodstream prevented.

Microsecond-pulse glow discharge atomic emission.

A microsecond pulsed glow discharge was produced with high pulse magnitude and small duty cycle. Time resolved emission and absorption spectroscopy was applied to study the processes of atomization, excitation and ionization in the glow discharge. Experimental results show that, without overheating the sample, the emission peak intensity is several orders greater than that obtained in the conventional dc mode. This implies that a much more intense plasma is generated during pulsed "on" region.

Derotational analysis of Cotrel-Dubousset instrumentation in idiopathic scoliosis.

Ten patients with idiopathic scoliosis were treated with posterior spinal fusion and Cotrel-Dubousset instrumentation. Computed tomographic scans and intraoperative photographs were used to evaluate the derotational effect of the Cotrel-Dubousset instrumentation. The frontal deformity was corrected from an average of 51 degrees to 15 degrees and the kyphosis from 9.5 degrees to 18 degrees. The amount of preoperative vertebral rotation was variable, however, and insignificant postoperative changes were documented in the majority of cases.

High-resolution two-grating spectrometer for dual wavelength spectral imaging.

A two-grating high-resolution spectrometer for dual wavelength imaging is demonstrated based on the standard Czerny-Turner mounting with an auxiliary grating and a mirror. A two-dimensional charge-coupled device (CCD) detector in the spectrometer focal plane allows simultaneous detection of two spectral intervals. Each spectrometer grating is driven by a high-precision stepper motor interfaced to a computer via home-made software. The software allows fast tuning of the gratings to a desirable spectral interval anywhere between 200 nm and 800 nm. The spectral interval widths are 2-3 nm for a ''high-resolution'' (2400 grooves/mm) grating and 4-5 nm for a ''low-resolution'' (1200 grooves/mm) grating. The resolution varies between 0.01 nm and 0.02 nm depending on the grating used. The performance of the spectrometer is demonstrated by detecting spectrally resolved images from a back-illuminated template and from a laser-induced plasma. The spectrometer can be useful for two-line spectroscopic diagnostics or can be expanded for multi-element spectral analysis.

Determination of the maximum temperature at the center of an optically thick laser-induced plasma using self-reversed spectral lines.

A method of temperature measurement based on the model developed by Bartels of an optically thick inhomogeneous plasma was applied to a laser plasma induced on a target containing barium. The method involves the intensity ratio measurement of two self-reversed Ba(II) lines. The temperature thus determined corresponds to the maximum temperature in the plasma center. The plasma temperature was measured for delay times between 0.5 micros and 10 micros in two spectrometer operating modes: the scanning mode and the dual-wavelength mode, the latter resulting in better precision. A detailed analysis of experimental errors was performed. The error strongly depended on the wavelength separation of the lines used. The most accurate results were obtained for the largest line separation. Using one line in the UV and the other in the visible region, the relative error was 2-6% for temperatures between 8000 K and 20 000 K. The distribution of the plasma temperature along the plasma height was measured in the same delay time range. The temperature was found to be uniform along the plasma vertical axis, thus confirming the plasma cylindrical symmetry.

Laser-enhanced ionization with avalanche amplification: detection of cesium at fg/mL levels.

The avalanche amplification of the laser-enhanced ionization signal of Cs atoms in a flame has been studied. Ionization of Cs atoms, enhanced by two-step excitation, was detected in hydrogen and propane flames. By employing the effect of avalanche amplification of electrons, high signal-to-noise ratio (approximately 10(4)) was obtained for a 100 ppt Cs solution. The extrapolated limit of detection was 30 fg/mL (ppq).

Automatic correction of continuum background in laser-induced breakdown and Raman spectrometry.

The goal of this work was the development and evaluation of an algorithm for the approximation and automatic subtraction of continuum backgrounds in laser-induced breakdown and Raman spectra. The background correction algorithm was applied to simple and complex spectra and its effect on identification accuracy was studied. Linear correlation was used for the identification of plastic samples using both laser-induced breakdown and Raman spectra. For both techniques, the algorithm successfully eliminated continuum background without compromising spectral integrity. A significant improvement in the percentage of correct plastic identifications was observed for Raman spectra. The approach should be applicable to a wide range of background correction problems in atomic and molecular spectroscopy.

Microchip laser-induced breakdown spectroscopy: a preliminary feasibility investigation.

A commercial, 7 microJ/pulse, 550 ps microchip laser is used to induce plasma on Pb, Si, Cu, Fe, Ni, Ti, Zn, Ta, and Mo foils and a Si wafer. The measured plasma lifetime is comparable with the duration of the laser pulse (a few ns). The plasma continuum radiation is low, while some of the strong resonance lines (e.g., Zn 213.86 nm) show self-reversal. Quantitative analysis is possible using non-gated detectors but analytical lines should be chosen with care to avoid reduction in the linear dynamic range. The mass removed (0.5-20 ng/pulse) is sufficient to yield spectra that are detectable with portable grating spectrometers equipped with non-gated, non-intensified detector arrays. The spectrum of Cd is detected with a broadband portable spectrometer (200-950 nm). The combination of the broadband spectrometer and the microchip laser is very promising for material identification, especially in field applications.

Rapid screening of polycyclic aromatic hydrocarbons and fingerprinting of environmental materials by laser-excited fluorescence spectrometry.

Laser-excited fluorescence of aromatic molecular vapors in a graphite furnace has been used as a rapid screening method for polycyclic aromatic hydrocarbons (PAHs) in various sample types and as a fingerprinting technique for crude oils, petroleum products and particulate matter. The simplicity and speed of the method indicate that it will be a useful method for PAH screening.

A Becquerel-disc phosphoroscope for the measurement of lifetimes in room-temperature phosphorimetry.

A Becquerel-disc phosphoroscope is constructed from a commercially available optical chopper with variable frequency and digital read-out. By use of a continuous source, phosphorescence lifetimes in the range 1-1000 msec can be measured with better than 4% relative standard deviation.