The need for “science” in fire scene investigation

فهرست عناوین اصلی در این پاورپوینت

فهرست عناوین اصلی در این پاورپوینت

● The need for “science” in fire scene investigation
● Fire Investigations and the Forensic Lab
● CRIMINALISTICS
● Debris containing suspected volatiles
● Method Selection
● Gas Chromatographic Analysis
● GC/MS: The Only Answer?
● Jumping straight to selected ions
● Blind Spot
● Lab Analysis
● Fire Investigations and the Forensic Lab
● What Can the Lab Tell?
● Field Testing
● Fire Investigations and the Forensic Lab
● CRIMINALISTICS
● Criminalistics (Non-Fire) Evidence
● Other Relevant ASTM Guidelines
● Fire Investigations and the Forensic Lab
● Keeping Up with the Dogs
● Fire Investigations and the Forensic Lab
● Thank you!

نوع زبان: انگلیسی حجم: 9.01 مگا بایت
نوع فایل: اسلاید پاورپوینت تعداد اسلایدها: 36 صفحه
سطح مطلب: نامشخص پسوند فایل: ppt
گروه موضوعی: زمان استخراج مطلب: 2019/05/16 05:49:58

لینک دانلود رایگان لینک دانلود کمکی

اسلایدهای پاورپوینت مرتبط در پایین صفحه

عبارات مهم استفاده شده در این مطلب

عبارات مهم استفاده شده در این مطلب

., fire, fuel, lab, –, method, suspect, synthetic, ignition, ignite, volatile, flame,

توجه: این مطلب در تاریخ 2019/05/16 05:49:58 به صورت خودکار از فضای وب آشکار توسط موتور جستجوی پاورپوینت جمع آوری شده است و در صورت اعلام عدم رضایت تهیه کننده ی آن، طبق قوانین سایت از روی وب گاه حذف خواهد شد. این مطلب از وب سایت زیر استخراج شده است و مسئولیت انتشار آن با منبع اصلی است.

https://www.txcourts.gov/All_Archived_Documents/ccaInformation/tcjiu/ppt/DeHaan-4.ppt

در صورتی که محتوای فایل ارائه شده با عنوان مطلب سازگار نبود یا مطلب مذکور خلاف قوانین کشور بود لطفا در بخش دیدگاه (در پایین صفحه) به ما اطلاع دهید تا بعد از بررسی در کوتاه ترین زمان نسبت به حدف با اصلاح آن اقدام نماییم. جهت جستجوی پاورپوینت های بیشتر بر روی اینجا کلیک کنید.

عبارات پرتکرار و مهم در این اسلاید عبارتند از: ., fire, fuel, lab, –, method, suspect, synthetic, ignition, ignite, volatile, flame,

مشاهده محتوای متنیِ این اسلاید ppt

مشاهده محتوای متنیِ این اسلاید ppt

fire debris fire investigations and the forensic lab are we missing things or keeping up with the dogs dr. john d. dehaan the need for science in fire scene investigation started to change in the ۱۹۸ ’s with new science based texts and a growing awareness of the need to get it right. nfpa began the process to create the ۹۲۱ guide court decisions daubert kumho joiner benfield et al. forced fire investigation to become more science based. the scientific method is expected. experts have to support their conclusions and demonstrate reliability acceptance and use of published peer reviewed data. fire investigations and the forensic lab if the investigator has no access to reliable answers based on good science he or she will turn to less reliable sources such as those the oral history promulgated often erroneously . the answers needed by today’s investigators go far beyond was there an ignitable liquid in the debris criminalistics debris containing suspected volatiles liquids charred or burned paper documents clothing and shoes tools and tool marks dry blood stains dna saliva glass fragments paint chips hairs and fibers firearms purpose aid in reconstructing events and human activities link suspect and scene or victim and suspect debris containing suspected volatiles the most requested service well studied and documented by astm practices isolation of volatiles from debris e۱۳۸۶ solvent extraction e۱۳۸۸ headspace sampling e۱۴۱۲ passive headspace c strip e۱۴۱۳ dynamic headspace charcoal tube e۲۱۵۴ spme method selection e۱۴۱۲ most commonly used easy low cost non destructive wide dynamic range may miss light ends hydrocarbons under c۷ if sampling time is too long may miss heavy ends hydrocarbons over c۱۸ if sampling time is too short or temperature is too low uses solvent extraction from carbon strip gas chromatographic analysis astm e۱۳۸۷ gc fid characterization by peak pattern and retention times original method low cost universal range well suited to gasoline paint thinner kerosene diesel light distillates and miscellaneous class blends and non distillate products proliferation of new custom petroleum products and non petroleum products de certified by astm e ۳ in ۲ ۱ gas chromatographic analysis gc ms became necessary to make many identifications first published as astm e ۱۶۱۸ in ۱۹۹۴ capable of separating aliphatics aromatics cycloalkanes and unsaturated compounds retention times peak profiles target compounds aromatic aliphatic ratios are now criteria now multiple classifications seven major classes divided by boiling point range plus automotive gasoline for a total of ۲۱. e۱۳۸۷ dropped as a recommended method in ۲ ۱ . heavy products no longer separated into kerosene class v. fuel oil class gc ms the only answer with solvent injection methods most gc ms operators sacrifice all peaks that elute before the solvent diethyl ether dimethyl ether or carbon disulfide this means that many light products including ethers ketones alcohols and c۶ range hydrocarbons are not recorded. these may be critical to the evidence. jumping straight to selected ions the overall pattern of peaks is very important in the characterization process start with the tic skipping straight to looking for aromatic v. aliphatic peaks or even target compounds can result in misleading conclusions blind spot because the heavy distillates are no longer split it is ok to report heavy petroleum distillate and list kerosene and diesel fuel as candidates this has led to mischaracterization of kerosene as diesel fuel and vice versa not by the analyst but in court by the investigator or the prosecutor . the analyst has to know what issues are important and modify the technique used. lab analysis not just for volatile accelerants identification of fuels laboratory identification by chemical physical or microscopic methods field tests fire tests fire investigations and the forensic lab furnishings and clothing are they natural fibers – cotton linen wool are they synthetic – polyester polypropylene nylon acrylic or are they thermoplastic or thermosetting or elastomers melting points ignition temperatures what volatile products do they generate foam – polyurethane polyether or latex are there fire retardants present what can the lab tell general type of fuel may help identify or exclude competent ignition sources. is the fuel first ignited cellulosic cellulosic derived from plants wood paper cotton linen cardboard susceptible to smoldering crumbly grey black ash on burning white smoke cellulosic fuels are susceptible to hot surface glowing ember ignition what can the lab tell is the fuel first ignited synthetic most synthetics are petroleum derivatives nylon polyethylene polystyrene polyester rarely ignitable by smoldering hot surface source easily ignited by open flame tend to melt and shrink away from heat most do not sustain smoldering combustion what can the lab tell synthetics may be thermoplastic – melts without degrading may be thermosetting resin – degrades chars may smolder other fuel types elastomers rubbers synthetic or natural leather – wool – silk proteinaceous from animals field testing even a simple ist ignition susceptibility test has a pedigree nfpa ۷ ۵ field flame tests for textiles and films – recommended practice ۱۹۹۷ small flame lighter or match held to bottom edge or corner of small sample held vertically in air. observe flame color and behavior observe smoke color and production odor blow out and observe smolder if any test ash texture fire investigations and the forensic lab why because the investigator will be expected to justify his or her conclusions about ignition flame spread and size of the fire on that data. cigarettes will not ignite most synthetics but will ignite most cellulosic materials. open flames will quickly ignite most synthetics or blends but then what will the fabric do self heating processes do not result in ignition of thermoplastic substrates. criminalistics debris containing suspected volatiles liquids charred or burned paper documents clothing and shoes tools and tool marks blood stain patterns dna saliva glass fragments paint chips hairs and fibers firearms purpose not just for identifying things aid in reconstructing events and human activities link suspect and scene or victim and suspect criminalistics non fire evidence investigators must be aware of proper collection and preservation methods for each type of evidence the lab needs to get involved in training chain of custody traces an item of evidence from its discovery to court. spoliation is the destruction or alteration of evidence. astm e ۸۶ establishes practices for …

کلمات کلیدی پرکاربرد در این اسلاید پاورپوینت: ., fire, fuel, lab, –, method, suspect, synthetic, ignition, ignite, volatile, flame,

این فایل پاورپوینت شامل 36 اسلاید و به زبان انگلیسی و حجم آن 9.01 مگا بایت است. نوع قالب فایل ppt بوده که با این لینک قابل دانلود است. این مطلب برگرفته از سایت زیر است و مسئولیت انتشار آن با منبع اصلی می باشد که در تاریخ 2019/05/16 05:49:58 استخراج شده است.

https://www.txcourts.gov/All_Archived_Documents/ccaInformation/tcjiu/ppt/DeHaan-4.ppt

  • جهت آموزش های پاورپوینت بر روی اینجا کلیک کنید.
  • جهت دانلود رایگان قالب های حرفه ای پاورپوینت بر روی اینجا کلیک کنید.

رفتن به مشاهده اسلاید در بالای صفحه


پاسخی بگذارید

نشانی ایمیل شما منتشر نخواهد شد. بخش‌های موردنیاز علامت‌گذاری شده‌اند *