Laser ablation-miniature mass spectrometer for elemental and isotopic analysis of rocks.

A laser ablation-miniature mass spectrometer (LA-MMS) for the chemical and isotopic measurement of rocks and minerals is described. In the LA-MMS method, neutral atoms ablated by a pulsed laser are led into an electron impact ionization source, where they are ionized by a 70 eV electron beam. This results in a secondary ion pulse typically 10-100 µs wide, compared to the original 5-10 ns laser pulse duration. Ions of different masses are then spatially dispersed along the focal plane of the magnetic sector of the miniature mass spectrometer (MMS) and measured in parallel by a modified CCD array detector capable of detecting ions directly. Compared to conventional scanning techniques, simultaneous measurement of the ion pulse along the focal plane effectively offers a 100% duty cycle over a wide mass range. LA-MMS offers a more quantitative assessment of elemental composition than techniques that detect ions directly generated by the ablation process because the latter can be strongly influenced by matrix effects that vary with the structure and geometry of the surface, the wavelength of the laser beam, and the not well characterized ionization efficiencies of the elements in the process. The above problems attendant to the direct ion analysis has been minimized in the LA-MMS by analyzing the ablated neutral species after their post-ionization by electron impaction. These neutral species are much more abundant than the directly ablated ions in the ablated vapor plume and are, therefore, expected to be characteristic of the chemical composition of the solid. Also, the electron impact ionization of elements is well studied and their ionization cross sections are known and easy to find in databases. Currently, the LA-MMS limit of detection is 0.4 wt.%. Here we describe LA-MMS elemental composition measurements of various minerals including microcline, lepidolite, anorthoclase, and USGS BCR-2G samples. The measurements of high precision isotopic ratios including (41)K/(39)K (0.077 ± 0.004) and (29)Si/(28)Si (0.052 ± 0.006) in these minerals by LA-MMS are also described. The LA-MMS has been developed as a prototype instrument system for space applications for geochemical and geochronological measurements on the surface of extraterrestrial bodies.

Pineal, Photoperiod and Gonadal Function in the Indian Palm Squirrel, Funambulus pennanti.

Effects of morning and evening injections of pineal 5-methoxyindoles (MI), melatonin (aMT) and 5-methoxytryptamine (MT), for 60 continuous days, were observed on the testes of sham-operated (SO) and pinealectomized (Px) Indian palm squirrel, Funambulus pennanti maintained under different photoperiods during the gonad active phase. Long photoperiod (LP) of 14L:10D appeared stimulatory to the testes and caused a significant increase in the weight and seminiferous tubule diameter of both SO and Px animals, as compared to the animals under natural day-length (NDL). Short photoperiod (SP) of 10L:14D had an inhibitory influence and reduced the testes weight and its tubule diameter. aMT and MT injections during evening hours significantly reduced testes weight and tubule diameter of SO and Px animals under NDL, LP and SP. However morning injections, under all conditions, were without any significant effect. The results suggest an inhibitory effect of aMT and MT, under above photoperiodic conditions, on the testes of this tropical mammal. The time of administration of the MI is important in the expression of the effect.

Preventable deaths among major trauma patients in Mersey Region, North Wales and the Isle of Man.

Preventable and unexpected deaths following injury were identified from among 1088 victims of major injuries arising in a defined population and area during a 12-month period. In hospital, 44 (16 per cent) deaths from blunt injury, one death from penetrating injury and one death from drowning were preventable. In patients sustaining blunt injuries, 22 per cent of non-head-injury deaths and 13 per cent of head-injury deaths were preventable. In all preventable head-injury deaths either a delay in operation (35 per cent) or no operation for mass lesions (65 per cent) occurred, often because of misdiagnosis as alcohol intoxication (22 per cent) or CVA (22 per cent). Multiple preventable factors were more likely in non-head-injury deaths and included missed injuries (67 per cent), poor airway care (57 per cent), delayed or no operation (52 per cent), undertransfusion (38 per cent) and inadequate surgery (19 per cent). By TRISS methodology the outcome was unexpected, in 53 per cent blunt injury deaths in hospital and 2.8 per cent of survivors. Three preventable blunt injury deaths (6.8 per cent) had probabilities of survival < 50 per cent and were not, therefore, identified as unexpected by TRISS. A preventable death rate of 16 per cent for blunt injuries equates to 638 preventable blunt injury deaths each year in England and Wales.

Effect of methylxanthines on motility and fertility of frozen-thawed goat semen.

We studied the effects of 2 methylxanthines (caffeine and theophylline) at different concentrations on goat sperm motility and live spermatozoa and on the percentage of acrosomal damage and fertility. Altogether, 144 semen samples collected from 12 bucks (3 each from Black Bengal and Beetal, and 6 from cross-breds) were diluted in TRIS extender, divided into 5 equal fractions; then caffeine and theophylline were added at 2 concentrations (2 and 5 mM) in different fractions. These samples were frozen in liquid nitrogen vapor, thawed at 37 degrees C for 15 sec, and evaluated for motility and other semen attributes. Addition of caffeine and theophylline had a stimulatory effect on goat spermatozoa. It was further observed that the effect of these agents was concentration-dependent, with 2 mM caffeine and 5 mM theophylline yielding the best results in respect to the percentage of motility in all 3 breeds of goats tested. Among the two methylxanthines used, caffeine was found to be the more effective in Improving motility than theophylline. There was no significant effect on the percentages of live spermatozoa and acrosomal damage due to the addition of these 2 methylxanthines to the extender. Fertility rates with Tris + 2 mM caffeine (60.20 %) and with Tris + 5 mM theophylline (58.88 %) extended semen were apparently higher than those with the Tris-diluted semen (50.0 %), although these differences were not significant.

The epidemiology of major injuries in Mersey Region and North Wales.

A prospective epidemiological study was undertaken to determine the workload and patient characteristics for a putative trauma centre in a large defined area. One thousand and eighty-eight patients were included: 430 brought in dead, 309 hospital deaths and 349 survivors. Types of injury were: blunt 76 per cent, penetrating 3.6 per cent, burns 5.8 per cent, other 14 per cent. The incidence of blunt injury was 19/100,000 for patients arriving alive at hospital and accounted for 0.08 per cent of new A & E attendances. Eight per cent of blunt injury patients were children, 68 per cent were adults and 24 per cent elderly. Major causes of injury were: road accidents 67 per cent and falls 26 per cent. In patients arriving alive after blunt injuries, those who subsequently died were significantly older, more severely injured and more physiologically impaired. Hospital mortality was 45 per cent for blunt, 43 per cent for penetrating injuries, and 67 per cent for burns. TRISS methodology indicated 53 per cent of hospital deaths from blunt injuries were unexpected. Practically, it is questionable whether the incidence of major injuries is sufficient to provide the volume of patients necessary to sustain a Level I Trauma Centre. Nevertheless, concentration of injury service is essential, since no hospital receives sufficient patients to develop and maintain expertise.

Characterization of bacteria by particle beam mass spectrometry.

A technique is described for detecting and characterizing bacteria on a single-particle basis by mass spectrometry. The method involves generation of a particle beam of single whole cells which are rapidly volatilized and ionized in vacuum in the ion source of a quadrupole mass spectrometer. The particle beam can be generated, with minimal sample handling, from a naturally occurring aerosol or from a solution of bacteria that can be dispersed as an aerosol. The mass spectrum is generated by successively measuring the average intensities of different mass peaks. The average intensity is obtained by measuring the ion intensity distribution at the particular mass (m/e) for ion pulses from more than 1,000 bacteria particles. Bacillus cereus, Bacillus subtilis, and Pseudomonas putida samples were analyzed to test the capability of the instrument for differentiating among species of bacteria. Significant ion-intensity information was produced over the m/e range of 50 to 300, an improvement over previous pyrolysis-mass spectrometry results. The complex mass spectra contained a few unique peaks which could be used for the differentiation of the bacteria. A statistical analysis of the variations in peak intensities among the three bacteria provided a quantitative measure of the reproducibility of the instrument and its ability to differentiate among bacteria. The technique could lead to a new rapid method for the analysis of microorganisms and could be used for the detection of airborne pathogens on a continuous, real-time basis.