A Forensic Traceability Index in Digital Forensic Investigation

Digital crime inflicts immense damage to users and systems and now it has reached a level of sophistication that makes it difficult to track its sources or origins especially with the advancements in modern computers, networks and the availability of diverse digital devices. Forensic has an important role to facilitate investigations of illegal activities and inappropriate behaviors using scientific methodologies, techniques and investigation frameworks. Digital forensic is developed to investigate any digital devices in the detection of crime. This paper emphasized on the research of traceability aspects in digital forensic investigation process. This includes discovering of complex and huge volume of evidence and connecting meaningful relationships between them. The aim of this paper is to derive a traceability index as a useful indicator in measuring the accuracy and completeness of discovering the evidence. This index is demonstrated through a model (TraceMap) to facilitate the investigator in tracing and mapping the evidence in order to identify the origin of the crime or incident. In this paper, tracing rate, mapping rate and offender identification rate are used to present the level of tracing ability, mapping ability and identifying the offender ability respectively. This research has a high potential of being expanded into other research areas such as in digital evidence presentation.

THE USE OF CHELATING RESIN FOR THE PRE-CONCENTRATION OF TRACE RARE EARTH ELEMENTS IN BIOLOGICAL SAMPLES AND THEIR DETERMINATION

Macroporous amino-carboxvlic chelating resin of acrylic acid series may concentrate trace rare earth in the presence of 0.1 mol/l α-hydroxy-isobutyric acid at pH 4.5.With 0.10 mol/l HCl as eluant rare earth may be eluted quantitatively and separated from Ca,Mg,Fe and Cu.This method is used to determine trace amount of rare earth in human hair,stone (in kidney and bladder),peanut,grape,strawberry,cucumber,pig liver and other biological samples.

Variations of trace elements and rare earth elements(REEs)treated by two different methods for snow-pit samples on the Qinghai-Tibetan Plateau and their implications

Although previous investigations of the trace elements in snow and ice from the Qinghai-Tibetan Plateau obtained interesting information about pollution from human activities on the plateau, most were based on traditional acidification methods.To emphasize the influence of the different sample-preparation methods on the records of trace elements and rare earth elements, snow samples were collected from glaciers on the Qinghai-Tibetan Plateau in China and prepared using two methods: traditional acidification and total digestion. Concentrations of 18 trace elements(Al, Ti, Fe, Rb, Sr, Ba, V, Cr, Mn, Li,Cu, Co, Mo, Cs, Sb, Pb, Tl, and U), along with 14 rare earth elements(REEs: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,Tm, Yb, and Lu), Y, and Th in the snow samples, were measured using inductively coupled plasma-sector field mass spectrometry(ICP-SFMS). The results showed that the mass fraction of the trace elements(defined as ratio of concentration in the acid-leachable fraction to that in the digested sample) such as Mo, Ti, Al, Rb, and V, varied from 0.06 to 0.5. The mass fraction of other trace elements varied from about 0.6 to more than 0.9; those of the REEs, Y, and Th varied from 0.34 to0.75. Lower mass fractions will lead to an overestimated contribution of other sources, especially human activities, and the underestimated fluxes of these trace elements(especially REEs, Y, and Th, as well as dust) if the REEs are used as the proxy for the crust dust. The two sample-preparation methods exhibited different REE normalized distribution patterns,REE ratios, and provenance-tracing results. The REE normalized distribution patterns and proxies in the digested samples are more reliable and integrated than those found in traditional acidification method for dust-provenance tracing.

Optimization of Dry Ashing of Whole Blood Samples for Trace Metal Analysis

Dry ashing is an established method. Ashing whole blood samples are, however, often difficult to carry out with significant sample loss, and the procedure is not well documented. A new procedure has been devel- oped and optimized to dry-ash whole blood samples for trace metal analyses. The procedure reduces both the dry-ashing time by more than two thirds and sample loss. The ashed sample can be readily used in subse- quent, simultaneous or individual analysis of several metals by ICP-OES, as demonstrated in the analysis of a whole blood sample. The new procedure is simple, inexpensive, and faster than the established method.

Surfactant Enhanced Chemofiltration of Zinc Traces Previous to Their Determination by Solid Surphase Fluorescence

Surfactant enhanced chemofiltration on Nylon membranes pre-treated with hexadecyltrimethylammonium bromide (HTAB) and eosin dye (eo) is proposed for zinc traces quantification by solid surphase spectro- fluorimetry (SSF, λexc = 532 nm;λem = 548 nm). Operational variables which have influence on quantitative retention of metal complex have been studied and optimized. At optimal experimental conditions, quantita- tive recovery was reached with a detection limit of 0.662 pg?L–1 and quantification limit of 2.20 pg?L–1. The calibration sensitivity was of 1.22 L?pg–1 for the new methodology with a linear range of 2.20 pg?L–1 to 779 pg?L–1 Zn (II). The tolerance levels of potential interfering ions were studied with good results. Recuperation studies were carried out by standard addition method applied to natural water samples (San Juan, Argentine) without previous treatment. The reproducibility (between-days precision) was also evaluated over 3 days by performing five determinations each day. CV% was 0.37. The performing obtained in sensitivity and selec- tivity thanks to chemofiltration step, converts the proposed methodology in an adequate alternative to con- ventional techniques for Zn (II) traces determination.

Green Photoluminescent Methodology for Aluminium Traces Quantification in 24-Hour Urine of Subjects with Different Exposition to Tobacco Smoke

The aim of this work has been to evaluate the aluminium (Al(III)) traces contents in 24-hour urine samples from subjects with different tobacco smoke expositions using a new methodology with 1,4-dihydroxy-9, 10-anthraquinone (Quinizarine, QZ) as a fluorosphore. Biological samples were tested using commercial reagent strips and clinical parameters. Al(III) was determined complexing with QZ followed by a solid phase extraction step using Nylon membranes as a solid support. The analyte was subsequently quantified by solid surface fluorescence (SSF, λem= 573, λexc= 490) with a detection limit of 0.88 μg L-1 and quantification limit of 2.69 μg L-1. The calibration curve was linear from 2.69 to 499.13 μg L-1 Al(III) (R2 = 0.9973). Urine samples were successfully analysed with an average recovery close to 100%. Solid phase extraction step showed efficacy to eliminate foreign ions and the highly fluorescent matrix own of urine. Results were validated by electrothermal atomic absorption spectrometry (ETAAS) with an adequate concordance. The new methodology has low operation cost with simple instrumentation and without organic solvent.

Distribution and Accumulation of Major and Trace Elements in Gypsum Samples from Lignite Combustion Power Plant

Flue gas containing volatile elements, fine fly ash particulates not retained by particle control devices, and limestone are the most important sources of trace and major elements (TMEs) in wet flue gas desulphurization (WFGD) gypsum. In this study, samples of gypsum slurry were separated into fine and coarse fractions. Multi-elemental analysis of 45 elements in the different size fractions of gypsum, slurry waters and lignite were performed by k0-INAA (k0-instrumental neutron activation analyses). The study found that the volatile elements (Hg, Se and halogens) in the flue gas accumulate in the fine fractions of gypsum. Moreover, the concentrations of most TMEs are considerably higher in the fine fractions compared to the coarse fractions. The exceptions are Ca and Sr that primarily originate from the limestone. Variations of TMEs in the finer fractions are dependent on the presence of CaSO4·2H2O that is the main constituent of the coarse fraction. Consequently, the content of TMEs in the fine fraction is highly dependent on the efficiency of separating the fine fraction from the coarse fraction. Separation of the finer fraction, representing about 10% of the total gypsum, offers the possibility to remove effectively TMEs from WFGD slurry.

The Relevant Physical Trace in Criminal Investigation

A criminal investigation requires the forensic scientist to search and to interpret vestiges of a criminal act that happened in the past.The forensic scientist is one of the many stakeholders who take part in the information quest within the criminal justice system.She reads the investigation scene in search of physical traces that should enable her to tell the story of the offense/crime that allegedly occurred.The challenge for any investigator is to detect and recognize relevant physical traces in order to provide clues for investigation and intelligence purposes,and that will constitute sound and relevant evidence for the court.This article shows how important it is to consider the relevancy of physical traces from the beginning of the investigation and what might influence the evaluation process.The exchange and management of information between the investigation stakeholders are important.Relevancy is a dimension that needs to be understood from the standpoints of law enforcement personnel and forensic scientists with the aim of strengthening investigation and ultimately the overall judicial process.

氢化物发生-电感耦合等离子体质谱法测定砂岩型铀矿样品中痕量镉

在砂岩型铀矿样品中,被测元素镉含量较低,每个质量丰度都存在不同类型的质谱干扰,而且各干扰元素的含量也存在较大差异,对电感耦合等离子体质谱法准确测量痕量镉造成比较大的困难。因此为了准确测量砂岩型铀矿样品中镉的含量,需要克服样品中不同类型的质谱干扰。采用氢化物发生-电感耦合等离子体质谱联用技术,被测镉元素气化后进入质谱仪中进行测量,可以有效解决测量元素镉的质谱干扰问题,同时提高了元素镉的灵敏度。建立了微波消解样品,连续流动注射进样氢化物发生-电感耦合等离子体质谱法准确测定砂岩型铀矿样品中痕量镉的方法。以盐酸溶液为介质,加入硫脲、亚铁氰化钾掩蔽剂溶液,以磷酸氢二铵、锶离子为增敏剂,优化了介质选择及浓度、硼氢化钾浓度、镉增敏剂的选择与用量等条件,并且有效解决了共存离子的干扰问题。研究表明:建立的连续流动注射氢化物发生-电感耦合等离子体质谱法测定砂岩型铀矿样品中痕量镉的方法,具有检出限低,正确度高,精密度好和适用范围宽等特点。方法检出限为0.001µg·g^(-1),精密度优于8.80%(以多次测量的相对标准偏差RSD来表征)。

“双减”政策落地的结构化困境与破解

“双减”政策正式发布已两年有余,国内开始更多地就该政策的落实落地情况开展大样本调查,但数据分析整体上还偏重于呈现表象问题。本研究尝试从经典的“结构-行动”理论出发,进一步深挖“双减”政策落地中的结构化困境。研究首先从政策本身出发,然后基于11个大样本调查,分别从顶层设计和实践两个层面分析当前凸显出的新问题、新怪象背后的深层次问题。研究发现:地方教育部门面临着上级政府部门自身实际操作偏离政策设定初心的问题;学校管理者和教师肩负着“既要、又要、还要”的多重期望;家长面临着“表面利好,实际难以做到”的困境。研究建议:在顶层设计层面,首先要从“双减”政策的根本意图出发,用中长期的工作目标与推进机制引领地方政府、教育部门和学校的行动;在实践层面,应着重于合力纾解家长的教育焦虑。

“双减”政策何以有效落地?基于“任务-主体-结构”的政策文本分析和对S省的调查

聚焦“双减”政策何以有效落地问题进行了两个新尝试。一是在研究范式上,从应然逻辑、实然状态和必然进路三个层面回应。二是在分析框架上,融合政策执行过程相关研究和结构化理论构建了突出目标导向、强化结构分析的“任务-主体-结构”政策执行过程模型,更契合我国复杂的政策执行环境。基于对“双减”政策文本和S省的落地实践分析发现:第一阶段的落地过程呈现出“运动式”治理的特征,但实际执行结构、落地条件和落地成效在内涵上远未达到设定目标。建议着力推动向“动员式”转型,以高质量教育体系建设为总抓手,有效回应家长对政策的价值需求。

广西地区犬和猫肠道病毒的病原学调查研究

为了解引起广西地区犬和猫腹泻等肠道病原的分布情况,并探究犬和猫新型肠道病毒感染的临床特征,为临床中及早诊治和防控肠道疾病提供参考依据,本试验采集宠物犬和猫粪便拭子样品394份(犬样品172份,猫样品222份),并通过聚合酶链式反应(PCR)或反转录酶-聚合酶链式反应(RT-PCR)筛查犬细小病毒(CPV)、猫瘟病毒(FPV)和查帕马细小病毒(ChPV)等13种主要犬和猫肠道病毒,并分析肠道病毒阳性率与年龄、性别、免疫状况和临床症状之间的相关性。结果显示,犬粪便样品中总阳性样品数为49份,占比28.49%;其中CPV的阳性率最高,达到15.12%,临床症状为典型的肠道症状;其次,犬粪便样品中还检测到犬冠状病毒(CCoV,4.65%)、猫杯状病毒(FCV,4.07%)、嵴病毒(KoV,4.07%)、博卡病毒(BoV,3.49%)、犬瘟热病毒(CDV,2.91%)和布法病毒(BuV,0.58%);其中11份粪便样品混合感染了2种及以上种类的肠道病毒,CPV感染占10份。幼龄犬对CCoV和FCV比较易感;各肠道病毒阳性率与性别无相关性,部分肠道病毒阳性率与免疫状况和临床症状有相关性。猫粪便样品中总阳性样品数为32份,占比14.41%;FPV的阳性率最高,达到8.11%;其次,猫粪便样品中还检测到新型肠道病毒,包括FCV(4.05%)、ChPV(1.35%)、BoV(1.35%)、BuV(0.45%)和猫冠状病毒(FCoV,0.45%);其中混合感染样品仅4份,而FCV感染占3份。FPV和BoV阳性率与猫的年龄和免疫状况存在相关性,各肠道病毒阳性率与猫的性别和临床症状无明显相关性。值得关注的是,犬和猫粪便中均可检测到A型流感病毒(IAV),阳性率分别为2.91%和0.45%。综上表明,CPV和FPV仍是引起犬和猫肠道疾病的主要病原,同时也是混合感染的重要组成;多种新型肠道病毒的阳性率虽然不高,但仍是引起肠道或肠外疾病中不可忽视的病原;IAV的检出再次强调了犬和猫作为“中间宿主”的重要作用。本试验结果不仅为犬和猫肠道传染病的防控提供预警,也为切断宠物-人IAV传播提供重要参考。

基于痕迹物证的放火案件现场勘查分析

放火嫌疑案件由于现场物品燃烧损毁严重,有价值的线索大量流失,致使侦破工作变得极为困难。应以物证为基础,重点分析烟熏、木材燃烧、玻璃破坏和金属变化等现场痕迹;做好现场询问、现场勘查和采集物证等工作;分析放火嫌疑与案件性质、起火点、引火源与起火物、起火原因和嫌疑人等,重建放火案件现场,为最终确认案件性质,侦破案件事实提供证据支撑。

武汉长江Ⅰ级阶地原状土样获取技术研究

本文分析了原状土样获取的技术标准现状和行业现状,研究了钻进方式、取样工具选取的适宜性综合分析、土样的封装及运输。对比试验研究表明,在武汉长江Ⅰ级阶地粘土层段采用锤击钻进配合使用敞口薄壁取土器,在砂土层采用锤击和回转组合钻进配合使用内置环刀取土器,辅以胶盖自封和胶带密封,取得的原状样品在现场质量评测、室内样品制备性和试验性方面均有比较良好的表现,基于此套方法获取的原状样原始结构受扰动较小,土的原始结构力保持良好。

纤维物证热损伤检验研究进展

在火灾、爆炸等事故调查中,对纤维热损伤痕迹特征进行分析,可为锁定嫌疑人、查明事实、重建现场及原因认定起到重要的作用。本文对国内外对人体毛发和纺织纤维的热损伤相关研究进行梳理,并对未来的研究方向进行了展望,以期为相关研究及事故调查应用提供参考。

污染场地土壤环境调查采样技术

在对污染场地的土壤环境进行调查时,采样是一项至关重要的工作内容。为实现调查样品的合理采集,从而获得足够科学准确的调查结果,对其现场的采样技术应用进行分析。包括污染土壤环境调查中的调查点布设与采样工作实施。希望通过本次的分析,可以为此类调查工作的有序进行与采样技术的合理应用提供一定参考。

运用多种数据调查高压供电侧故障引发的火灾事故

介绍一起在台风天气下发生的大型厂房火灾事故的调查过程,在前期调查过程中现场起火点不定、引火源不明、物证无法提取,起火原因无法定性的情况下,通过调取火灾现场与原因相关的视频数据、网络数据、电表数据、高压录波数据等多维电子数据,结合高压供电故障痕迹形成的机理和诱发因素,综合分析认定了火灾原因。该起火灾的调查过程可为相关类型火灾事故调查提供参考。

微波消解-电感耦合等离子体质谱(ICP-MS)法测定黑土地地表基质调查样品中碘

碘是活跃元素,价态多,各价态间易相互转化,使其具有熔点低、易挥发,严重记忆效应的独特性质,其分析一直是个挑战。传统方法如半熔法、高压密闭法等存在操作难度大、消解时间长、工作效率低等问题。通过采用硝酸-氢氟酸微波消解处理样品,并利用电感耦合等离子体质谱(ICP-MS)法测定碘含量,克服了传统碘分析方法的一系列问题。研究了不同酸体系和赶酸时间对样品分解效率和挥发损失的影响,同时验证了不同冲洗液对降低碘记忆效应的效果。在此基础上,确定了最佳反应条件为7 mL硝酸+1 mL氢氟酸混合酸比例,180℃赶酸控温程序,并采用2%NH_(3)·H_(2)O充当冲洗液,降低了ICP-MS测定过程中的记忆效应,提高测试的稳定性。为验证该使用国家一级标准物质对方法的准确性和精密度进行验证,结果表明,方法的准确度(Δlgc)为0.001~0.004,相对标准偏差(RSD)为1.2%~3.4%,相关系数为0.9998,检出限为0.17 mg/kg,定量限为0.54 mg/kg,表现出较好的准确度和精密度,满足规范要求。通过实际样品测试,进一步验证了方法的可行性,实验结果表明,相对偏差在1.6%~4.1%。方法操作方便、试剂用量少、工作效率高,适用于测定黑土地地表基质调查样品,同时也为碘的快速、准确分析提供了一种可行的解决方案。