2016.6
About Instruments Today No. 207
Forensic Investigation
Dr. Henry Chang-Yu Lee's Seminar: New Technologies for Criminal Investigation in the 21st Century [ 下載 PDF ]
The Innovative Application of Forensic Science and Technology for Crime Investigation [ 下載 PDF ]
Jeff, Cheng-Lung Lee
Forensic science is applied science for courtrooms. It's one of the main objectives that high-tech investigation can be used to retrieve more information and evidences for courtrooms from crime scenes. Forensic scientists should be following trends of technology and developing innovative methods to collect and verify evidences leading to opportunities for solving criminal cases. It is also a predictable trend to take advantage of novel technologies for crime investigation. In conclusions, we mentioned that the potential national security issues should not be neglected. There concluded three suggestions: 'Strengthening the judicial officers with education of forensic science'; 'Reinforcing research and development of forensic science and technology that could not be under controls by others' and 'Extending the service fields of forensic science'. We hope that throw a sprat to catch a whale and attract more scholars and experts to invest their efforts to these suggestions.
The Determination of Wounding Capability of Firearms and Ammunition [ 下載 PDF ]
Hsien-Hui Meng
In Taiwan, possess of wounding capability is the basic condition for certain types of firearms and ammunition to be defined as illegal weapons. Thus the wounding capability of these weapons should be determined before their owners are indicted. We here describe forensic examination methods such as function tests, muzzle energy test, witness plate test, and X-ray image interpretation that are used to determine the wounding capability of firearms and ammunition. Forensic examination results of guns and cartridges from real criminal cases are also illustrated to facilitate the readers to understand the detriment caused by illegal weapons to the society.
Forensic Applcations of Nanotechnology—A Brief Discussion [ 下載 PDF ]
Yung-Fou Chen
Nanotechnology for the development of modern science and technology have a significant impact, just as DNA technology for the past 50 years, the contribution of biotechnology. Many nanotechnology has been widely used in a variety of fiber (fever clothes, stain clothes), cosmetics (sunscreen, collagen), writing instruments (long-lasting ink) as well as a variety of polymer materials. In order to analyze the crime scene in the visible, but only partially identified conventional forensic tools or can not identify the new nano material evidence, or difficult sampling on traditional evidence, only destructive to analyze physical evidence, this lab to AFM non-destructive method of research as the main front entry of the sample. AFM principle of operation of nanoscale atomic force measurement between the fine probe sample using the instrument of the distance between the probe and thus presumably with the surface of the structure drawn by computer graphics and the sample surface, And enables researchers to explore the surface morphology of various samples of fine-nanometer level, and to help establish a variety of repositories. Nano-level surface analysis of the sample, Allows us to better understand the evidence of the whole picture. Currently forensic and academic research related to AFM major international instruments towards identification, fiber and hair, blood and other direction. AFM has a considerable potential for analyzing the morphology and structure of all kinds of detailed evidence, the future could become a powerful tool to aid the work of forensic trace evidence, and therefore previously been Evidence of the potential for all kinds of unconventional filing scan, more emphasis is to identify instruments with paper and ink samples and trace evidence analysis for identification of potential research paper on the sample, the closer to the general practice of traditional forensic analysis, and assist in resolving the current forensic tools or methods can not analyze the object.
The Evaluation of Drug-Testing Device for Ketamine and Its Metabolites in Body Fluid [ 下載 PDF ]
Wei-Jhih Lin, Sheng-Meng Wang, Yung-fou Chen, Tung-Jun Wu, Fu-Der Mai
We have been in the war on drugs for over twenty years. According to data from the Ministry of Justice, in recent years, drug abuse problem is under control, but the relapse rates are still high. The teenage student of emerging drug abuse problems caught the attentions of government and society. In drug control activities, drug urine tests are used for arresting and identification of drug addicts. However, this test method does show a number of restrictions to limit the test proficiency. Saliva and sweat detections are both emerging and feasible method drug-testing approaches, after taking sample collection and test sample authentication into consideration; saliva test method is the most prominent approach. Thresholds of saliva test for drugs are nation by nation, and a variety of factors, including conditions, race and diet metabolism also influence the thresholds. In order to design the saliva rapid screening test kits, it is important to establish local drug thresholds.
The On-Site X-ray Stress Measurement and Vibratory Stress Relief Technique [ 下載 PDF ]
Shang-Ching Chen, Tao-Sheng Hsu, Weite Wu
Although the residual stress is often to appear on the industries, due to the residual stress that is not observed, the industries don't know that the residual stress will affect the deformation, failure of accuracy, and decreasing fatigue strength of the workpieces. So, we must consider that it cannot influence the mechanical properties of the workpieces. Now, we will introduce the vibratory stress relief (V.S.R) technique that spontaneously makes the vibration waves to reduce the residual stress of the inside of the workpieces. And, we use the non-destructive stress measure technique to get the values of the residual stress. In the long term, we will make sure of the safety of using the workpieces. The vibratory stress relief (V.S.R) technique has been proved some advantages, such as to lessen the residual stress effectively, to avoid from the deformations, and increase the strength of the materials.
Investigation of Trimethylindium Flow Rate on Electro-Optical and Chemical Properties of InN Epilayer Grown on GaN/Al2O3 Substrate [ 下載 PDF ]
Wei-Chun Chen, Shou-Yi Kuo, Fang-I Lai, Chien-Nan Hsiao
III-nitride is important material for high power light emitting diode (LED) devices. Specially, InN has attracted the most attention among the III-V nitrides because of its noticeable narrow band gap (0.65 eV), small effective mass and high electron mobility. Due to most InN films were prepared by MOCVD. However, metal-organic precursor often included carbon, hydrogen and oxygen. Therefore, we discussed the chemical and electro-optical properties of InN films grown on MOCVD-GaN lyaer with different trimethylindium flow rate. The InN films were characterized by secondary ion mass spectrometry, X-ray photoelectron spectroscopy photoluminescence and Hall effect. InN films were grown on MOCVD-GaN/Al2O3 substrate by plasma-assisted metal-organic molecular beam epitaxy. Secondary ion mass spectrometry and X-ray photoelectron spectroscopy results showed that carbon and hydrogen of trimethylindium precursor were incorporated during InN films growth. Also, the C and H concentrations increase with increasing trimethylindium flow rate. On the other hand, the oxygen concentration decreases with increasing trimethylindium flow rate. A relatively high C, H and O concentration exists near the surface of the InN film. Therefore, before etching, the film exhibits the high carrier concentration of 5.57 × 1019 cm−3 and low mobility of 192 cm2/V-s. After etching, the etched InN film exhibited a decreased carrier concentration of 3.31 × 1019 cm−3, increased electron mobility of 335 cm2/V-s. Optical properties showed that the PL spectra exhibited blue-shift with increasing V/III flow ratio due to the Burstein-Moss effect. However, high carrier concentration was measured probably due to nitrogen vacancies and impurity contributed. Therefore, blue shift of the optical absortion is caused by high carrier concentration.
Refractive Index Profi ling of Various Optical Fibers [ 下載 PDF ]
Chun-Jen Weng
A direct image method of surface refl ectivities on a cleaved fiber end with a halogen lamp illumination to measure the refractive index profiling (RIP) is proposed in this study. A polished black glass with a surface flatness λ /20 (λ = 632.8 nm) is used to be the reference standard for measuring the spectral reflectivity of the fiber end. By the image calibration between the fiber end and the black glass, not only the nonuniformity of the sensitivity but also the spectral responsivity of the CCD pixels is eliminated to achieve the high spatial accuracy. Various measuring errors such as a fiber terminator, oblique incident on the fiber end and the intensity fluctuations of the lamp are improved to precisely measure the RIP. The RIP of various fibers such as a single-mode fiber, ultra-high numerical aperture fiber, a graded-index fiber can be precisely measured to verify the system performance. The resolution and accuracy for measuring RIP on the cleaved fiber end can be achieved about ~0.001 and ~0.003, respectively.
