“…Clearly, the transfer of automotive paint causing the formation of a smear is caused by shear stress, which is mainly created by friction, but the mechanism of material detachment and transfer is complex. 14,15 Polarity of the chemical groups on the surface as well as the charges generated by triboelectric effect can influence paint transfer. What is most crucial, however, is the heat generated during impact (rapid sliding) which can soften or melt the automotive paint where the transfer may resemble viscous fluid flow.…”
Section: Discussionmentioning
confidence: 99%
“…The frictional work is responsible for the transfer of the paint as a smear. 14–16 Figure 1.(a) Accessories to be adapted for the impact tester to produce paint smears. (b and c) Paint-transfer substrate clipped/attached to the striker.…”
Section: Methodsmentioning
confidence: 99%
“…The frictional work is responsible for the transfer of the paint as a smear. [14][15][16] To realistically emulate a vehicle collision, two tunable shock absorbers were employed (Fig. 2), which allowed adjustment of the effective force constant and damping coefficient associated with the collision (i.e., the mechanical coupling between the colliding bodies).…”
Paint smears represent a type of automotive paint sample found at a crime scene that is problematic for forensic automotive paint examiners to analyze as there are no reference materials present in automotive paint databases to generate hit-lists of potential suspect vehicles. Realistic paint smears are difficult to create in a laboratory and have also proven challenging to analyze because of the mixing of the various automotive paint layers. A procedure based on an impact tester has been developed to create smears to simulate paint transfer between vehicles during a collision. Data collected from twenty-four original equipment manufacturer (OEM) paints in simulated collisions using an impact tester with a steel (inert) substrate to simulate vehicle to vehicle collisions shows that attenuated total reflection infrared microscopy can isolate individual paint layers. For each OEM paint sample, the corresponding smear obtained was dependent upon the conditions used. By varying these conditions, the number of distinct layers obtained could be tuned for each of the OEM paints investigated. Furthermore, the IR spectrum of each layer extracted from the paint smear using alternating least squares was found to compare favorably to an in-house OEM paint infrared spectral library for each layer as the correct match (make and model of the vehicle from which the smear originated) was always found as a top five hit in the hit-list. The results of this study indicate that paint smears developed using an impactor can serve as the basis of realistic proficiency tests for forensic laboratories.
“…Clearly, the transfer of automotive paint causing the formation of a smear is caused by shear stress, which is mainly created by friction, but the mechanism of material detachment and transfer is complex. 14,15 Polarity of the chemical groups on the surface as well as the charges generated by triboelectric effect can influence paint transfer. What is most crucial, however, is the heat generated during impact (rapid sliding) which can soften or melt the automotive paint where the transfer may resemble viscous fluid flow.…”
Section: Discussionmentioning
confidence: 99%
“…The frictional work is responsible for the transfer of the paint as a smear. 14–16 Figure 1.(a) Accessories to be adapted for the impact tester to produce paint smears. (b and c) Paint-transfer substrate clipped/attached to the striker.…”
Section: Methodsmentioning
confidence: 99%
“…The frictional work is responsible for the transfer of the paint as a smear. [14][15][16] To realistically emulate a vehicle collision, two tunable shock absorbers were employed (Fig. 2), which allowed adjustment of the effective force constant and damping coefficient associated with the collision (i.e., the mechanical coupling between the colliding bodies).…”
Paint smears represent a type of automotive paint sample found at a crime scene that is problematic for forensic automotive paint examiners to analyze as there are no reference materials present in automotive paint databases to generate hit-lists of potential suspect vehicles. Realistic paint smears are difficult to create in a laboratory and have also proven challenging to analyze because of the mixing of the various automotive paint layers. A procedure based on an impact tester has been developed to create smears to simulate paint transfer between vehicles during a collision. Data collected from twenty-four original equipment manufacturer (OEM) paints in simulated collisions using an impact tester with a steel (inert) substrate to simulate vehicle to vehicle collisions shows that attenuated total reflection infrared microscopy can isolate individual paint layers. For each OEM paint sample, the corresponding smear obtained was dependent upon the conditions used. By varying these conditions, the number of distinct layers obtained could be tuned for each of the OEM paints investigated. Furthermore, the IR spectrum of each layer extracted from the paint smear using alternating least squares was found to compare favorably to an in-house OEM paint infrared spectral library for each layer as the correct match (make and model of the vehicle from which the smear originated) was always found as a top five hit in the hit-list. The results of this study indicate that paint smears developed using an impactor can serve as the basis of realistic proficiency tests for forensic laboratories.
“…Yapışkan bantlar; tecavüz, cinayet, kaçırma ve patlayıcı maddeler de dâhil olmak üzere adli olaylarda yaygın olarak kullanılmaktadır. Örneğin şüpheli kurbanın ağzını ve ellerini bağlamak istediğinde, yasadışı mallarla paketleri mühürlemek istediğinde veya patlayıcı cihazlar üretirken telleri izole etmek için yapışkan bantlar kullanılır [25]. Bir suç mahallinde bulunan yapışkan bantlar genellikle birbirine yapışır veya belirli bir alt tabakaya bağlanır.…”
Section: Optik Koherens Tomografi İle Yapışkan Bant Altında Gizli Parunclassified
Öz Suç olaylarının çözümlenmesinde ve suçlunun belirlenmesinde yardımcı olan Adli Bilimler alanı gün geçtikçe önemini arttırmaktadır. Olay yerinden elde edilen deliller aracılığı ile kişilerin tanımlanmasında her kişide farklı yapıya sahip olan DNA molekülü olayları çözüme kavuşturmaktadır. Adli amaçlı olarak da kullanılan DNA molekülü Adli Antropoloji ve Adli Genetik alanında kullanılan ortak moleküldür. Antropoloji insan bilimidir ve insanı tüm yönleri ile ele alır. Adli Antropoloji alanı ise suçlunun tespitinde, kimliği belirsiz cesetlerin kimliklendirilmesinde, yaş, cinsiyet ve etnik kökenin belirlenmesinde yardımcı olmaktadır. Antropoloji içerisinde kullanılan Antik DNA sayesinde geçmiş ile günümüz arasında köprü kurulabilmektedir. Olay yerinde her zaman vücut sıvısı veya biyolojik materyaller yer almaz. Bir iskelet kalıntısından olayın çözümlenmesinde devreye Adli Antropoloji girmektedir. İskeletleri kimliklendirme aşamasında Somatoskopi ve Antropometri teknikleri kullanılmaktadır. Bu iki teknik Adli Antropoloji alanında önemli yere sahiptir. Adli Genetik alanı ise olay yerinde bulunan vücut sıvıları ve biyolojik materyaller ile ilgilenir. Bu sıvıları laboratuvar testlerine tabii tutarak DNA analizlerinin sonuçlanmasını sağlamaktadır. Her iki bilim dalının da suçlunun tespitinde DNA molekülünden yararlandığı görülmektedir. DNA molekülünden elde edilen DNA parmak izi kişiye özgüdür ve bu durum suçlu profillerinin belirlenmesi açısından muazzam bir durumdur. DNA Parmak izi ile ilgili yeni gelişmeler söz konusudur. Yeni geliştirilen Optik Koherans Tomografi Sistemi ve ParaDNA Vücut Sıvısı Kimliklendirme Sistemi, DNA parmak izi üzerinde oldukça olumlu sonuçlar ortaya koymaktadır. DNA'nın geri kazanımı ile ilgili çalışmalar sonucunda ise gizli DNA parmak izi olarak tanımlanan izlerin kolayca elde edilebilmesi sağlanmaktadır. Geri kazanım ile olayların çözümlenmesi kısa sürede olmakta ve bu durum birçok laboratuvarın rutin sırasını değiştirmektedir. Aynı zamanda parmak izinin alınması zor olan materyaller üzerinden parmak izinin profillendirilmesine imkân sağlamaktadır.
“…By the process of polymerization, long chains of monomer units are joined together to form polymers. [4] In polymer composites, reinforcing fibers are embedded into a polymer matrix. Reinforcing fibers chosen may be short fibers or thin continuous fibers.…”
This article presents a thorough review of biofiber-based hybrid composites along with the discussion on its mechanical and tribological performance in the polymeric matrix. Emphasis is centered on plant fibers as animal fibers are not frequently used and mineral fibers possess serious health issues. All five types of plant fibers and their hybrids are reviewed. Hybridization of plant fibers synergetically combines individual benefits while eliminating the limitations of single fiber use. Study regarding fiber origin, processability and extraction techniques, composition, chemical surface treatments, and applications are presented. Finally, the results obtained are summarized and future developments are discussed. The review concludes that biofiber hybrid composites possess great potential in several applications provided that satisfies design constraints and polymeric matrix compatibility issues.
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