Sem/X-Ray Applications to the Forensic Science Field

1976 ◽  
Vol 34 ◽  
pp. 390-391
Author(s):  
K. Culbreth
Keyword(s):  
Forensic Science ◽  
Depth Of Field ◽  
Surface Phenomena ◽  
Criminal Cases ◽  
Forensic Evidence ◽  
Science Field ◽  
X Ray ◽  
Hit And Run ◽  
Evaluation Of Evidence ◽  
Scanning Electron

The introduction of scanning electron microscopy and energy dispersive x-ray analysis to forensic science has provided additional methods by which investigative evidence can be analyzed. The importance of evidence from the scene of a crime or from the personal belongings of a victim and suspect has resulted in the development and evaluation of SEM/x-ray analysis applications to various types of forensic evidence. The intent of this paper is to describe some of these applications and to relate their importance to the investigation of criminal cases.The depth of field and high resolution of the SEM are an asset to the evaluation of evidence with respect to surface phenomena and physical matches (1). Fig. 1 shows a Phillips screw which has been reconstructed after the head and shank were separated during a hit-and-run accident.

Mini-Scanning Electron Miscroscope Concept

1974 ◽  
Vol 32 ◽  
pp. 406-407
Author(s):  
Donald J. Evins ◽  
Robert J. Engle
Keyword(s):  
Electron Microscope ◽  
Depth Of Field ◽  
X Ray ◽  
Rapid Scan ◽  
Operational Characteristics ◽  
Electron Microscopes ◽  
The Cost ◽  
Scanning Electron Microscopes ◽  
Large Research ◽  
Scanning Electron

The scanning electron microscope has already established itself as one of the most useful instrument developments in recent years. The SEM provides 20 times greater useful magnifications and up to 500 times greater depth of-field than the best optical microscopes. Until the introduction of the Mini-SEM concept, the cost and complexity of SEM's has limited their use primarily to large research oriented laboratories.Design features, specifications, and operational characteristics will be reviewed. The Mini-Rapid Scan with resolution of 750Å will be described, along with the Mini-SEM with resolution of 150 to 200Å. Both of these are table top scanning electron microscopes. Various specimen stage options will be illustrated. Other accessories extending the SEM's versatility will be described, such as the energy dispersive x-ray system

Effects of a Clean Subcritical Degreasing System on Wool Fibers

2021 ◽  
Vol 116 (5) ◽  
Author(s):  
Qiao Xia ◽  
Yinxuan Wang ◽  
Meina Zhang ◽  
Zongcai Zhang ◽  
Hong Dai
Keyword(s):  
Disulfide Bonds ◽  
Structural Changes ◽  
Depth Of Field ◽  
Diffraction Experiment ◽  
X Ray ◽  
Scale Layer ◽  
Wool Fibers ◽  
Α Helix ◽  
Thermal Stability Of ◽  
Scanning Electron

It makes sense to use environmentally friendly methods of degreasing in fur-making process. In this study, subcritical n-pentane was used to degrease wool fibers. Thermogravimetric analysis (TGA) was used to observe and analyze the properties of the subcritical n-pentane degreased wool fibers. The results showed that the thermal stability of the fibers increased. Fourier Transform Infrared (FTIR) spectroscopy was used to analyze the structural changes of macromolecular chains in wool fibers. It was found that when the pressure was higher than 0.4 MPa, the wool fibers underwent a conformational change with the α-helix changing to β-folding. If the pressure was as high as 0.6 MPa, the disulfide bonds in the wool fibers scale layer appeared to break. X-ray powder diffraction experiment was used to study changes in wool fiber aggregation morphology. It was demonstrated that the crystalline zone of wool fibers changed and the fibers index grew, from 22.89% to 30.19%. Field emission scanning electron microscopy and ultra-depth of field microscopy was used to analyze changes in the surface morphology of wool fibers. The results suggested that after the treatment, the wool fibers were not damaged and the impurities on the wool surface were reduced.

scholarly journals Challenges of the forensic science facing new technologies.

2021 ◽  
Vol 1 (7) ◽  
pp. 48-61
Author(s):  
Delia Magherescu
Keyword(s):  
Artificial Intelligence ◽  
Forensic Science ◽  
New Technologies ◽  
Scientific Evidence ◽  
Digital Technologies ◽  
Current Paper ◽  
Criminal Proceedings ◽  
Criminal Cases ◽  
Forensic Evidence ◽  
Criminal Matters

In the era of new technologies, used in the field of criminal justice, the forensic science has passed real challenges facing those means of gathering and administering scientific evidence in criminal proceedings. Artificial intelligence and how it meets the judiciary is a well-known question for the hightech in the field. The current paper aims at analyzing and discussing the features the judicial activity in criminal matters is characterized with during the criminal proceedings. The most important elements of new technologies come to state the consequences that they produce in criminal cases investigated by means of forensic evidence including new digital technologies. In order to achieve the proposed goal of the current paper, certain main purposes have been highlighted, which consist particularly in the procedure of using methods of forensic science for the investigation of crimes, as well as elements of new means of technologies including artificial intelligence. The proposed topic is carried out through qualitative research methods conducted on approaching challenges of the forensic science facing new technologies, combined with in-depth elements of criminal proceedings.

scholarly journals The Development of an X-ray Spectral Database for Forensic Science

2001 ◽  
Vol 9 (3) ◽  
pp. 8-13
Author(s):  
Dennis Ward
Keyword(s):  
Forensic Science ◽  
Energy Dispersive Spectrometer ◽  
Full Potential ◽  
Federal Bureau ◽  
Federal Bureau Of Investigation ◽  
X Ray ◽  
Large Numbers ◽  
Science Laboratories ◽  
Spectral Database ◽  
Scanning Electron

The Scanning Electron Microscope (SEM) with associated Energy Dispersive Spectrometer (EDS) is commonly used to characterize the structure and elemental composition of a wide variety of materials of forensic significance. When these materials are extremely limited in size, SEM/EDS is often the only suitable method for characterization available in forensic science laboratories.Because of the inability to access SEM/EDS data from large numbers of materials, the Federal Bureau of Investigation (FBI) laboratory believes that this discipline has not realized its full potential. The usefulness of SEM/EDS has been limited by the inability to archive spectra within a utility having a true database architecture. The FBI Laboratory has designed such an X-ray database, consisting of storage, query, and display utilities unique to X-ray spectroscopy.

Managing Uncertainty in Forensic and Expert Evidence Cases

2019 ◽  
pp. 115-140
Author(s):  
Carolyn Hoyle ◽  
Mai Sato
Keyword(s):  
Decision Making ◽  
Forensic Science ◽  
Expert Testimony ◽  
Expert Evidence ◽  
Criminal Cases ◽  
Forensic Evidence ◽  
Turn On ◽  
Decision Frames

This chapter examines issues arising from cases that turn on forensic and expert evidence, focusing on how the Criminal Cases Review Commission investigates such applications and makes its decisions. Drawing on a sample of sixty-one cases involving forty-two applicants, the chapter shows how the Commission makes decisions in cases that ‘turn on’ forensic science and expert testimony. It also considers the influence of developments in the ‘surround’ of the Commission and how the surround affects the Commission's decision field — the broad setting within which decision-making at the Commission takes place. Finally, it analyses the role of decision frames in the Commission's decision-making on forensic and expert evidence cases, noting that such frames are characterised by uncertainty and even anxiety. Concerns about the interpretation and presentation of forensic evidence at trial are discussed, along with the legal and narrative frames of decision-making in forensic and expert evidence cases.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

The Broad Applications of the Scanning Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 20-21
Author(s):  
C. T. Nightingale ◽  
S. E. Summers ◽  
T. P. Turnbull
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscopy ◽  
Surface Topography ◽  
Great Depth ◽  
Resolving Power ◽  
Depth Of Field ◽  
Pictorial Representations ◽  
Scanning Electron

The ease of operation of the scanning electron microscope has insured its wide application in medicine and industry. The micrographs are pictorial representations of surface topography obtained directly from the specimen. The need to replicate is eliminated. The great depth of field and the high resolving power provide far more information than light microscopy.

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