Low Temperature Techniques in Biomedical Microanalysis

Many diseases are associated with a change in the distribution of diffusible ions at the cell or tissue level. These diseases can profitably be studied by X-ray microanalysis. This technique for the study of ion distribution requires the use of cryoprepared specimens. Analysis at low or medium resolution can be carried out on thick or semi-thick cryosections, or on frozen-hydrated or freeze-dried embedded bulk samples. Such analyses are particularly useful in the initial stages of an investigation, or when many data from a large number of samples have to be acquired. Quantitative analysis is then usually carried out with the peak-to-local background method: by taking the background in the same energy range as the characteristic peak, an intrinsic correction for absorption of X-rays within the sample is made. X-ray microanalysis of cultured cells prepared by freeze-drying can also be carried out in this way. Analysis at high resolution has to be carried out on thin sections: cryosections, or sections of freeze-substituted or freeze-dried embedded tissue. For the latter type of specimens, the use of low-temperature embedding methods may have important advantages. Quantitative analysis of thin sections is carried out by the established continuum method

Elemental Microanalysis of Biological Specimens

Although X-ray microanalysis in the electron microscope is the most common method for microanalysis of biological specimens, other methods of elemental microanalysis (electron energy loss spectroscopy, scanning Auger microanalysis, and proton, ion, and laser microprobe analysis) may provide important complementary information and help overcome some of the limitations of electron probe X-ray microanalysis. Despite differences in physical principles and instrumentation, the various microanalytical methods have much in common with regard to specimen preparation, quantitative analysis, and interpretation of analytical data. A common approach to microanalytical problems in the biological sciences, irrespective of the analytical techniques used, seems therefore indicated

Correction for Extraneous Background in X-Ray Microanalysis of Cell Cultures

Some practical aspects of the X-ray microanalysis of cell cultures have been investigated. Cells were cultured on titanium grids covered with Formvar films and analyzed at 100 kV either in the scanning transmission (STEM) or transmission mode (TEM) of the electron microscope. Different holders, grids and configurations were compared with respect to the relative contribution of different factors to the extraneous background in the X-ray spectrum. When low atomic number holders are used, the contribution to the spectrum of electrons scattered through high angles, may be negligible. In practice this may result in negative values for the contribution of these scattered electrons to the background. Computer programs for correction of the extraneous background should ignore these negative values and replace them by zero. When a brass holder is used, the contribution to the spectrum from electrons scattered through high angles becomes more important than that of the uncollimated radiation. The position of the analyzed cell relative to the grid bars is more important than the choice of grid or holder type. The data show that for the specimens used in the present study the correction for extraneous background is of little importance and can be neglected

Experimental and numerical study on the performance of the smooth-land labyrinth seal

In turbomachinery the secondary flow system includes flow phenomena occurring outside the main channel, where the gaseous medium performs work on blades. Secondary air distribution constitutes a very complex and closely interrelated system that affects most of the gas turbine components. One of the most important examples of the secondary flow is leakage occurring in seals, e.g. at the rotor and stator tips, on the shaft or on the sides of the blade rim. Owing to its simplicity, low price, easy maintenance and high temperature capability, the labyrinth seal is a prime sealing solution that may be selected from numerous types of sealing structures applied in turbomachinery. For this reason, an experimental study of this particular structure has been carried out. The paper presents leakage performance of the smooth-land labyrinth seal

Applications of Scanning Electron Microscopy and X-Ray Microanalysis in Inner Ear Pathology

Surface pathology of inner ear structures so far described in detail concern cochlear and vestibular hair cells and the stria vascularis. In man, surgical intervention into the inner ear is very uncommon and when performed is in general with the primary objective of destroying the diseased peripheral end organs. The vast majority of inner ear tissue available for use with scanning electron microscopy (SEM) is therefore obtained from animals. The present paper reviews the progression of surface pathology caused by aminoglycoside antibiotics, acoustic overstimulation and in a guinea pig strain with genetic inner ear disease. The primary site of onset of surface pathology differs, depending on the underlying cause. Advanced surface pathology shows a similar type of morphological degeneration independent of cause. The combination of SEM and energy dispersive X-ray microanalysis (XRMA) of inner ear pathology has as yet been reported in only three studies, all concerning inner ear fluids or otoconia

Comment on ``Strangeness enhancement in p+Ap+A and S+A+A interactions at energies near 200 AA GeV"

We argue that the recent analysis of strangeness production in nuclear collisions at 200 $A$ GeV/$c$ performed by Topor Pop {\it et al.} \cite{To:95} is flawed. The conclusions are based on an erroneous interpretation of the data and the numerical model results. The term ``strangeness enhancement" is used in a misleading way.Comment: 4 pages REVTEX 3.0, no figures; Comment submitted to Physical Review

p_T-fluctuations in high-energy p-p and A-A collisions

The event-by-event p_T-fluctuations in proton-proton and central Pb-Pb collisions, which have been experimentally studied by means of the so-called Phi-measure, are analyzed. The contribution due to the correlation which couples the average p_T to the event multiplicity is computed. The correlation appears to be far too weak to explain the preliminary experimental value of Phi (p_T) in p-p interactions. The significance of the result is discussed.Comment: 5 pages, 2 figures, minor improvement

Technique of double incision laparoscopic cholecystectomy (DILCH) as an alternative to SILS

Background. Single incisions laparoscopic surgery (SILS) applied for cholecystectomy can ensure a good cosmetic effect expecting without no visible scarring cosmetic effect after surgical procedures, but needrequires implementation of special ports, as well as articulating and banked instruments to be more comfortable for the surgeon. The aim of this paper is to present three three-ports cholecystectomy through two well hidden incisions – umbilical and suprapubic, – performed by with typical laparoscopic instruments. Methods. Ten consecutive elective patients with typical, symptomatic cholelithiasis were qualified for DILS cholecystectomy. All acute cases were excluded from intervention. Typical CO2 pneumoperitoneum was done after umbilical skin incision. Two ports, 5 mm and 11 mm, were inserted in the maximum external edges of this incision. The second incision for 11 mm optical trocar for optic was performed in the suprapubic median line, just in the hairy zonewithin the hair line, to hidden conceal himit. Results. DILCH were performed without any conversions to classical LCH or open cholecystectomy. Each procedure was different according to technical improvement of access and manipulation of instruments manipulations. Time of interventions ranged between from 2 hours for the first patients to 1 hour for the last according to the learning curve. No complications were observed and all patients were discharged as after conventional LCH. Conclusions. DILCH as a three three-port laparoscopic intervention, performed with typical laparoscopic instruments, is more convenient for the surgeon than single incision LCH. Transfer of the optic from the umbilical port site to hidden the concealed suprapubic hairy region gives thereprovides more space for instruments but didn’t did not spoil theed good cosmetic effect of intervention. This procedure is easy to learn and in case of technical problems we can always apply additional ports like foras in typical LCH. Background. Single incisions laparoscopic surgery (SILS) applied for cholecystectomy can ensure a good cosmetic effect expecting without no visible scarring cosmetic effect after surgical procedures, but needrequires implementation of special ports, as well as artic- ulating and banked instruments to be more comfortable for the surgeon. The aim of this paper is to present three three-ports chole- cystectomy through two well hidden incisions – umbilical and suprapubic, – performed by with typical laparoscopic instruments. Methods. Ten consecutive elective patients with typical, symptomatic cholelithiasis were qualified for DILS cholecystectomy. All acute cases were excluded from intervention. Typical CO2 pneumoperitoneum was done after umbilical skin incision. Two ports, 5 mm and 11 mm, were inserted in the maximum external edges of this incision. The second incision for 11 mm optical trocar for optic was per- formed in the suprapubic median line, just in the hairy zonewithin the hair line, to hidden conceal himit. Results. DILCH were performed without any conversions to classical LCH or open cholecystectomy. Each procedure was different according to technical improvement of access and manipulation of instruments manipulations. Time of interventions ranged between from 2 hours for the first patients to 1 hour for the last according to the learning curve. No complications were observed and all patients were discharged as after conventional LCH. Conclusions. DILCH as a three three-port laparoscopic intervention, performed with typical laparoscopic instruments, is more convenient for the surgeon than single incision LCH. Transfer of the optic from the umbilical port site to hidden the concealed supra- pubic hairy region gives thereprovides more space for instruments but didn’t did not spoil theed good cosmetic effect of intervention. This procedure is easy to learn and in case of technical problems we can always apply additional ports like foras in typical LCH.

Strangeness counting in high energy collisions

The estimates of overall strange quark production in high energy e+e-, pp and ppbar collisions by using the statistical-thermal model of hadronisation are presented and compared with previous works. The parametrization of strangeness suppression within the model is discussed. Interesting regularities emerge in the strange/non-strange produced quark ratio which turns out to be fairly constant in elementary collisions while it is twice as large in SPS heavy ion collision.Comment: talk given at Strangeness in Quark Matter 98, submitted to J. Phys.