Earticle

Oxygen is an essential element for animal life. Although deaths due to lack of oxygen occur frequently under various indoor conditions, verifying hypoxia as the cause of mortality has remained elusive. Also, the biomarkers indicating the hypoxia-induced death have not yet been clearly identified. In this study, we screened potential metabolites of which levels in animal blood can be differentiated under hypoxic conditions. Metabolites of post-mortem bloods exposed to various low-oxygen levels (3%, 5%, 8% and 12%) were compared with those from mice ambient air. GC/MS analysis showed increase in levels of lactic acid, succinic acid, uric acid and uracil in post-mortem blood from mice exposed to moderately low oxygen level (12%). Whereas samples from mice in much lower oxygen level (3% and 5%) did not show significant differences in metabolites levels. Importantly, the increase rate of these metabolites appeared to be proportional to survival time after hypoxia, suggesting that there are hypoxia-inducible cell responses including the avoidance of oxygen-dependent energetic metabolism. The results suggest that both oxygen concentration and duration exposed to hypoxia condition determine cellular metabolic pathways to increase their consequent metabolites in animal fluids, which may be used as biomarkers for tracking hypoxia.

Grayanotoxins are neurotoxins that are mainly produced by plants of Genus Rhododendron. Among the plants native to Korea, R. yedoense (royal azalea) and R. brachycarpum are widely known to contain grayanotoxins, R. mucronulatum (azalea), on the other hand, is known to be non-toxic and its flower has been widely eaten as food. However, a few azalea intoxication cases have been reported, showing the possibility of azalea toxicity. In this study, we tried to determine the cause of the reported azalea intoxication cases if they were caused by genuine toxicity of azalea or by royal azalea mistaken as azalea. Samples of three species of Rhododendron were collected and analyzed by LC-MS/MS to detect Grayanotoxin Ⅰ and Ⅲ. As a result, 4 out of 10 azalea flower samples contained grayanotoxins suggesting that some azaleas can cause grayanotoxin poisoning. To identify differences between the toxic and non-toxic azaleas, DNA barcoding was performed. By comparing their barcoding sequences of chloroplasts, it was found that the toxic azaleas contain DNA sequences which present in royal azaleas in rbcL region. The relationship between the change in rbcL region and synthesis of grayanotoxins is not clear, but it implies that more DNA changes could have occurred in the toxic azaleas to produce grayanotoxins. In conclusion, azalea flowers with DNA changes can cause grayanotoxin poisoning. Further studies on the DNA differences and the effect of environment on the expression of grayanotoxins are necessary to figure out the cause of the random toxicity by azalea.

As the seizures of cannabis have risen since 2018, the presumptive identification of THC has been studied to determine the presence of THC in seized cannabis using color tests. Because the color tests are simple to perform, inexpensive and give results that can be viewed by the naked eyes, four different color tests were examined in this study. Duquenois- Levine reagent, Fast blue B salt, Fast blue BB salt and 4-Aminophenol were compared to detect THC in the Cannabis specimens. The seized cannabis flowers were used as specimens and four reagents of Duquenois-Levine, Fast blue B salt, Fast blue BB salt, 4-Aminophenol were prepared according to the guidelines of the UNODC. GC-MS was utilized to measure the LODs of THC for the color tests applied. Duquenois-Levine, Fast blue B salt, Fast blue BB salt and 4-Aminophenol showed distinctive color changes in the presence of cannabis. By Duquenois-Levine, the color changed to blue-violet, Fast blue B salt to purple-red color, Fast blue BB salt to reddish orange color and 4-Aminophenol to blue. The LODs of THC by the four reagents were as follow: Duquenois-Levine and 4-Aminophenol showed 2 μg, Fast blue B salt was 0.6 μg and Fast blue BB salt was 0.8 μg. It was interesting to note that the blue color by 4-Aminophenol indicated the presence of THC, while pink color indicated the presence of CBD. In conclusion, Fast blue B salt was the most applicable color test to determine the presence of cannabis with the lowest LOD of THC.

The convolutional neural network (CNN) is a deep learning method to recognize images with high accuracy and low error rate. In this study, we performed classification of DNA profiles based on electropherogram images using the CNN. 1,800 DNA profiles images of three control DNAs (007, 2800M, 9947A) were used for CNN model as a dataset. A dataset was divided into the train and test data set, and 1,500 and 300 images were used, respectively. The CNN model used the LeNet-5 architecture, and an accuracy of model was estimated by k-fold cross validation. Both the training data set and test data set showed an accuracy of 1.0 and a loss rate of 0 with 50 epochs. All 300 images of test data set exactly matched the actual data, and the predict probability of match for each element showed 0.579.

In recent years, along with the increase in the use of electrical energy, the number of electrical disasters tends to increase. An electrical connection exists to use the electrical energy where it is needed, and the contact resistance increases at the electrical connection, causing electrical heat generation. Electric fires are caused by such electrical heat generation. In this paper, we evaluated the fire risk of electrical connection finish treatment methods. It has been confirmed that the twist connection by the finish treatment method of the electrical connection causes a relatively high temperature rise, resulting in a high risk of fire. When a dedicated connection terminal was used for the electrical connection, the temperature rise occurred in a limited manner, and the temperature change to the extent that it led to a fire did not occur. Therefore, in order to prevent fires from occurring at the electrical connections that inevitably occur, it is judged that fires can be minimized by using dedicated connection terminals.

As the use of electric energy increases, the number of electric disasters also increases. In this study, the contents of forensic analysis to investigate the cause of an electric shock accident during an electric disaster are described. When an electric shock accident occurs, a singular point such as an electrical melting mark appears on the electrical installation, and the electric shock path can be identified by analyzing this point. In addition, on the clothes which were interacting with the work tools used by the victim, peculiar traces of human tissue adhesion and carbonization perforation appear. Finally, the victim’s body is left with traces of electrical burn formed by the electric shock accident. In this way, unique traces remain in an electric shock accident, and through the inspection of these traces, it is possible to identify the electric shock path and dangerousness in the event of an electric shock accident. Therefore, it is expected that the contents of this paper can be used as a basic reference for an accurate investigation of the cause of electric shock accidents.

This paper dealt with the development of the smart kiosk based fire judgment support system. Smart functions were designed by installing speech recognition and a motion sensor on a 55-inch kiosk. In addition, judgment documents, SOP(Standard operating procedure), R&D reports, papers, and other documents were stored and accumulated as data. The GUI(Graphical user interface) is designed with consideration of the user’s convenience. To maintain the security of the stored data, a log-in function was added before starting the system. Prior to developing this system, a researcher had to come to the office and use a computer to find the necessary data while they are in the process of dismentling the evidence. However, after the development of this system, data on the evidence can be accessed immediately in the process of dismentling the evidence. Therefore, we suggest that researchers using this system can improve their effectiveness and the quality of their judgment.

Most of the fingerprints found at crime scenes are in latent fingerprint forms, and it is difficult to observe those fingerprints with the naked eye. Even if it is assumed that a latent fingerprint is remaining on an object, the method of developing the latent fingerprint differs depending on the surface type of the object. Therefore, a study must be performed by imprinting a latent fingerprint on an object, which is similar to the evidence found at a crime scene, to find an appropriate latent fingerprint development method. To do this, time and costs occur to recruit research participants, and these may cause disruption on arresting a suspect in a short time. Lothar Schwarz’s artificial latent fingerprint printing method, using an artificial sweat solution and an inkjet printer, can be used in a latent fingerprint research instead of using real human fingerprints. Although the major purpose of Schwarz’s method is to print out uniform fingerprint images on an A4 paper. Therefore, this approach has a limitation that it can only make imprints of fingerprints on thin and flexible materials such as copy papers and PVC films. To address this shortcoming, a Synthetic Fingerprint Generator(SFinGe, University of Bologna) computer program, a Printed Circuit Board(PCB) technique, and liquid latex are used to create an artificial fingerprint cast. With this new method, artificial latent fingerprint can be made on any surface types of material to find an appropriate latent fingerprint development method quickly during police investigations.

Cigarette-related garbage can be easily found on anywhere, even at the crime scene. Cigarette evidence can provide DNA evidence and have been used in investigation for a long time. If very small amounts of DNA are detected or in a mixture with contaminants, it is hard to analysis DNA In this case, fingerprints can be conclusive evidence to identify suspects. However, when 1,2-indanedione (1,2-IND) was applied to cigarettes, the background was stained and made it difficult to identify ridges. Therefore, latent fingerprint development research is needed in such case, and when DNA analysis is difficult on cigarettes. In this study, 1,2-IND and Ruthenium tetroxide (RTX) were used to compare the development of latent fingerprints on cigarettes, which are porous surfaces. On the filter part of cigarettes, latent fingerprints were clearly developed on both 1,2-IND and RTX, but on the body part of cigarettes, 1,2-IND reacted with tobacco leaves and showed a fluorescence reaction on the background, making it difficult to identify the ridges of the fingerprints. On the other hand, when RTX was applied, clear ridges were appeared on the body part of cigarettes. In addition, the RTX did not leave many stains on the background. The 1,2-IND is currently the most effective latent fingerprint development technique on porous surfaces but it is estimated to react with amino acid components contained in a cigarette. Therefore, when there is a need to develop latent fingerprints on cigarettes, it is confirmed that RTX reagent is much more effective than 1,2-IND reagent.

Audio recordings are used widely as crucial evidence due to the popularity of smartphones. However, the digital evidence submitted voluntarily may be questioned for its authentication. Since most smartphones provide the function of digital editing files, they could be exposed to crime as being edited maliciously. Primarily, it could be severe in the case of voluntary submission via information and communications networks. This paper proposed the forensic method for authentication of audio recordings generated by the Voice Recorder application from Samsung smartphones. First, we analyzed and compared the file structures and timestamps of audio recordings between the normal state without manipulation and the manipulated state. Then, we analyzed the spectrogram of audio recordings. Finally, by analyzing the timestamps of the media-log for audio recordings, we confirmed the authentication method for the audio recordings forensically.

Tetramethylammonium(TMA, tetramine) is a toxic quaternary ammonium compound, consisting of four methyl groups attached to a central nitrogen atom. TMA has been detected in a number of marine organism that are eaten by humans. In the past, most cases of TMA intoxication have occurred through eating seafood containing TMA, such as carnivorous gastropods. Nowadays, TMA hydroxide(TMAH) that decomposes to produce TMA is used widely in the manufacture of semiconductors and liquid crystal displays (LCDs). As a result, the case of TMA intoxication is increasing. TMA acts directly on nicotinic and muscarinic receptors that are responsible for depolarization and, at high doses, blockage of depolarization. TMA may cause nausea, vomiting, headache, impaired vision, temporary blindness, salivation, lacrimation, fasciculation and convulsion and motor paralysis. The symptoms of TMA intoxication generally are mild and transient because of rapid elimination of TMA from the body. However, in severe cases, paralysis of the respiratory muscles can occur and this causes death. In this study, we analyzed TMA in femoral blood, heart blood and gastric contents of victim. The concentrations of TMA in femoral blood and heart blood were 7.95 mg/L and 13.1 mg/L, respectively. This case can be considered as a good reference when studying the relationship between TMA-induced death and blood concentration.

Phenol (also called carbolic acid) is a white or colorless crystalline solid, and it dissolves well in water and exists in a liquid state. Phenol has been mainly used as precursors for plastics, drugs and pesticides. In addition, phenol has been used as a preservative and a local anesthetic. Phenol causes severe irritation and corrosion on skin and other tissue by protein degeneration, and it may cause harmful effects on central nervous system and heart resulting in dysrhythmia, seizure, and death. Fatal cases by ingestion or intravenous injection of phenol for suicide were described in literatures, and there are many cases of death from accidental inhalation or absorption through the skin in workplace. In this study, we present two cases of death from phenol poisoning. Analysis of phenol in blood and tissues was performed by head space-solid phase micro extraction-gas chromatography-mass spectrometry method (HS-SPME-GC/MS). In one case, the concentration of phenol in heart and peripheral blood were 205.2 mg/L and 19.1 mg/L, respectively. In both cases, the concentration of phenol in liver and kidney tissue were 15.1-259.6 mg/kg and 45.8-38.5 mg/kg, respectively.