| Objectives Drowning is defined as death from asphyxia within24hours of submersion in water, and always a problem in judicial practice and scientific research in forensic pathology. It has not been accepted and unified that some biological and chemical indexes were sufficiently specific or sensitive for diagnosis of drowning. At present, the detection off Oreign plant elements such as diatoms is assessed and the value of diatom test as the "golden standard" is evaluated. But in recent years, most of the reported drowning for different waters (fish ponds, rivers, ponds, libraries, swimming pool water, etc.) of drowning cases identified or retrospective study, and only focuses on the detection of diatom body organs, and ignores the drowned as concentration of diatom influence on test results, different regional diatom drowning cases organs inspection there is no unified qualitative and quantitative diagnosis of the reference standard, and in2008the People’s Republic of China issued by the ministry of public security of the People’s Republic of China industry standard GA/T813-2008diatom nitric acid in the human body tissues and organs broken machine to test is not clear in this problem, also not clear microscopic counting method. Therefore, this research is focused on through the establishment of a simple, fast, diatom drop counting methods, to further improve the quantitative standard of diatom inspection appraisal drowning, clearly define the experiment time, check the consumption of materials and reagents, to support the forensic identification of the qualitative and quantitative detection of drowning. In addition, due to the complicated water environment, and there are many different kinds of diatom, shape different, the diatom species composition of different water sources and different, so can pass to detect the ratio, the diatom species and composition of compared with algae in the water, to infer the water of the dead position, so as to provide help for the inspection.Methods The method of the "three districts, four images and two fields":draw20micro litre different diatom drowned droplet concentration on glass slide, natural dried to form a diameter of about7mm round spot, with round spot center as the midpoint, circular, etc can be divided into three concentric zone, the central area, middle area, edge area. Count will be rounded to the "ten" word is divided into four quadrants, respectively in each area, each quadrant equidistant points according to the central area, middle area, edge area2from each high power field count, a total of24a high view diatom count (12,48horizons at the same time, take count), the combined average for a quick view of the submerged liquid at high magnification,(x40) concentration of diatom, numerical accurate to two decimal places.At the same time, by the ministry of public security of the human body tissues and organs in the diatom nitrate broken machine to test method provided by the count of diatom, the results as a reference.Results1. Diatoms drop counting methods, selection of12vision,24and48horizons pair wise comparison:12and24horizons when p<0.05, the difference was statistically significant;12and48horizons, p<0.05, the difference was statistically significant;24and48horizons (p>0.05), while there was no statistically significant difference.2. Drowned liquid directly manufactured piece and will be drown drops, enrichment in reduction is made after drop (centrifugal) after a comparison, a centrifugal diatom will loss and loss about10%.3. Use the method of the "three districts, four images and two fields" to count, when the concentration of liquid drowned diatom concentration below2548per milliliter or higher than36162per milliliter, the actual measured values and theoretical values appear deviation.4. Use the method of the "three districts, four images and two fields" to count,6groups of unknown samples respectively according to the method and enrichment. If the actual measured value and theoretical value, there is no deviation between is considered authentic test results. Then, six groups of water samples,2times the concentration of believable results appear most times,5times;4times the concentration and the concentration of8times times, all appeared four times.5. Not drowning in yunnan province diatom content in human body lungs with the method of the "three districts, four images and two fields "for testing, not detected in lung and digestive fluid smear diatoms.6. The method of the "three districts, four images and two fields" and the ministry of public security of the human body tissues and organs in the diatom nitrate broken machine to test (GA/T813-2008), method count, the count is more simple and feasible, easy to operation and counting method is easy to grasp, more scientific and rigour.Conclusions1. Use high power optical microscope (x40) observation count diatoms, the method of the "three districts, four images and two fields" of good quantity and concentration detection of diatoms, as compared with the ministry of public security of the human body tissues and organs in the diatom nitrate broken machine to test (GA/T813-2008) method is used to count the diatoms have credibility and counting is easy to operate, counting method is simple, feasible and easy to grasp, etc. More scientific and rigour.2. Use the method of the "three districts, four images and two fields" to count, the confidence intervals between the2548-36162(unit:/ml).3. Use the method of the "three districts, four images and two fields" to detect unknown samples, commonly detected more easily will test again after the enrichment of diatom, its optimal concentration range between2～8times.4. Not drowning diatom was never detected in the lungs, through the way such as water, food and air enter the body of the diatom does not affect the results.5. Water samples each for a centrifugal, thereby causing loss to the diatom, the loss is about10%, in the actual operation to reduce the number of centrifugal.6.. Not detect the diatoms in kunming city tap water. |
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