We propose the analysis method of spur mark distance for discrimination of inkjet printers using a measuring microscope. The conventional method is the measurement of the pitch and the mutual distance of the spur marks which depend on the model of inkjet printers. Therefore, it is difficult to discriminate the same models of inkjet printers by the conventional method. First, we established the analysis method to obtain the spur mark distance indented by one rotation of spur gear and examined the difference of the distances in a printer using correlation coefficients. Next, we applied this method to discriminate 60 inkjet printers of the same model. As a result, the correlation coefficients between the same printers approximated to 1. On the other hand, the correlation coefficients between the different printers were widely distributed in the range from –1 to 1. These results indicate that our proposed method can distinguish printers of the same model and be a useful tool for discrimination of printers in combination with the conventional method.
We experienced a case of successful identification of an unknown body found at breakwater based on root canal treatment. After matching the dental findings of the body to the treatment history of individual's dental records, 23 teeth showed agreement in findings. Although 8 teeth did not agree in findings, they were consistent in terms of dental treatment history. There was inconsistency in the remaining tooth. This tooth was determined as intact, but the dental records indicated the existence of a resin composite restoration on that tooth. However, that inconsistency never became a critical determinant factor. Comparison of periapical radiographs of the body with the dental records revealed that the right mandibular first premolar teeth showed considerable similarity to the images of a broken endodontic instrument and a alveolar bone resorption caused by the leakage of root canal sealer at the middle of the root. Given the above information, we concluded that the identification as the same individual is reasonable. It was thought that a case where the findings of a dental medical accident helped to confirm the identity was unusual.
Five commercial DNA extraction kits for microbial DNA in soil were evaluated in terms of the extraction efficiencies of artificially-spiked extracellular DNA in soil. Commercially-available purified DNA derived from the sperm of Clupea harengus (Atlantic herring) was homogeneously premixed in blank soil samples and extracted using the kits. The spiked DNA in each of the extracts was quantitated by real-time PCR to evaluate extraction efficiency using a specific primer set for the mitochondrial 16S rRNA gene of Clupea harengus. Only the Extrap Soil DNA Kit could extract the DNA from all types of soils spiked at 10 μg/g soil (vegetable garden soil 0.85%, courtyard soil 0.30% and virgin andosol 0.027%), whereas other kits (Nucleospin Soil, Power Soil DNA Isolation Kit, ISOIL and ISOIL for Beads Beating) could not extract the DNA larger than the quantitation limit (0.020%) from the courtyard soil and the virgin andosol which exhibited high phosphate absorption coefficient. Skim milk concentration and bead-beating time using the Extrap Soil DNA Kit were optimized for 20 mg/g soil and 30 s, respectively. Significant PCR inhibition was not observed under the optimized condition.
In this study, we developed a fast screening method for the detection of herbicides paraquat (PQ) and diquat (DQ) in human whole blood, serum, and urine by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) after solid-phase dispersive extraction (SPDE). Prior to SPDE, whole blood samples and serum samples were deproteinized with acetonitrile. PQ and DQ were extracted from these pretreated samples and urine samples by SPDE with Oasis® WCX, a mixed-mode, reversed-phase/weak acid cation exchange sorbent. The retained PQ and DQ were eluted with the small amount (8 μL) of matrix solution (saturated solution of α-cyano-hydroxycinnamic acid in 1:1 v/v 0.2 % trifluoroacetic acid in water/acetonitrile). The extracted PQ and DQ were instantaneously detected by MALDI-TOF-MS in the positive reflector ion mode. The singly charged radical ions M+· appearing at m/z 186.11 (PQ) and 184.10 (DQ), and the deprotonated ion [M-H]+ appearing at m/z 183.10 (DQ) were mainly observed. PQ and DQ were successfully detected from even a small amount (0.1 mL) and low concentration (0.05 μg/mL) of sample assumed mild poisoning. The limit of detection (S/N>3) for PQ and DQ were 0.002 μg/mL and 0.01 μg/mL, respectively.