Study of chemical modifications in acidified ignitable liquids analysed by GC-MS

In this work, mixtures of gasoline with sulphuric acid and diesel fuel with sulphuric acid were analysed by gas chromatography&-mass spectrometry (GC&-MS). The results showed considerable qualitative and semi-quantitative modifications in the chromatographic profiles of the ignitable liquids (ILs). In the case of acidified gasoline, the alteration of the abundances of aromatic compounds and the hydrolysis of an oxygenated compound such as methyl tert-butyl ether (MTBE), in addition to the immediate and unexpected appearance of tert-butylated compounds were observed. In the case of acidified diesel fuel, the alteration of aromatic compounds occurred. These sequential changes were then studied in detail in order to explain the chemical modifications taking place. These extensive chemical modifications may be considered as a new chromatographic profile distortion effect, the acidification of ILs. As such modifications are not generally taken into account in the criteria followed to assess the classification of an IL, we propose some recommendations helping to the identification of acidified ILs. This information can be especially useful to detect and identify non-burned ILs from seized or failed improvised incendiary devices made with mixtures of sulphuric acid&-IL, or ILs altered intentionally with the aim to modify their composition

Analysis of pre-ignited Improvised Incendiary Devices using portable Raman

In this work, the use of a portable Raman spectrometer is evaluated for the non-invasive analysis of two types of pre-ignited improvised incendiary devices (IIDs), the classic Molotov cocktails and the chemical ignition Molotov cocktails (CIMCs). The most common ignitable liquids (ILs) used to make classic Molotov cocktails (gasoline, diesel fuel, kerosene and ethanol) were measured in seven different clear and colored glass bottles to evaluate if the container features could hamper the Raman measurements. The results showed that the portable Raman spectrometer can be employed to detect ILs in glass bottles without disturbances. Chemical changes on the ILs are produced when they are mixed with acid; therefore, to evaluate the use of the portable Raman spectrometer for the analysis of CIMCs required an investigation of how time and movement influence the measurements. Thus, two different IL&-sulfuric acid mixtures commonly used to make CIMCs (gasoline&-sulfuric acid and diesel fuel&-sulfuric acid) were measured over time under static and motion conditions. In spite of the intense fluorescence encountered in both CIMCs, it was possible to identify the acid and the gasoline for the first hours of the reaction both in the static and motion experiments. Concerning the diesel fuel present in the CIMC, it underwent instantaneous chemical changes under both measurement conditions, showing high fluorescence that impeded its identification. In view of the results achieved, the portable Raman spectrometer can be a useful instrument for the rapid, non-invasive and safe analysis of pre-ignited IIDs

Study of Spectral Modifications in Acidified Ignitable Liquids by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy

In this work, the spectral characteristics of two types of acidified gasoline and acidified diesel fuel are discussed. Neat and acidified ignitable liquids (ILs) infrared absorption spectra obtained by attenuated total reflection Fourier transform infrared spectroscopy were compared in order to identify the modifications produced by the reaction of the ILs with sulfuric acid. Several bands crucial for gasoline identification were modified, and new bands appeared over the reaction time. In the case of acidified diesel fuel, no significant modifications were observed. Additionally, the neat and acidified ILs spectra were used to perform a principal components analysis in order to confirm objectively the results. The complete discrimination among samples was successfully achieved, including the complete differentiation among gasoline types. Taking into account the results obtained in this work, it is possible to propose spectral fingerprints for the identification of non-burned acidified ILs in forensic investigations related with arson or the use of improvised incendiary devices (IIDs)

Analytical tools for the analysis of fire debris. A review: 2008-2015

The analysis of fire debris evidence might offer crucial information to a forensic investigation, when for instance, there is suspicion of the intentional use of ignitable liquids to initiate a fire. Although the evidence analysis in the laboratory is mainly conducted by a handful of well-established methodologies, during the last eight years several authors proposed noteworthy improvements on these methodologies, suggesting new interesting approaches. This review critically outlines the most up-to-date and suitable tools for the analysis and interpretation of fire debris evidence. The survey about analytical tools covers works published in the 2008&-2015 period. It includes sources of consensus-classified reference samples, current standard procedures, new proposals for sample extraction and analysis, and the most novel statistical tools. In addition, this review provides relevant knowledge on the distortion effects of the ignitable liquid chemical fingerprints, which have to be considered during interpretation of results

Acid alteration of several ignitable liquids of potential use in arsons

Ignitable liquids such as fuels, alcohols and thinners can be used in criminal activities, for instance arsons. Forensic experts require to know their chemical compositions, as well as to understand how different modification effects could impact them, in order to detect, classify and identify them properly in fire debris. The acid alteration/acidification of ignitable liquids is a modification effect that sharply alters the chemical composition, for example, of gasoline and diesel fuel, interfering in the forensic analysis and result interpretation. However, to date there is little information about the consequences of this effect over other accelerants of interests. In this research paper, the alteration by sulfuric acid of several commercial thinners and other accelerants of potential use in arsons is studied in-depth. For that purpose, spectral (by ATR-FTIR) and chromatographic (by GC&-MS) data were obtained from neat and acidified samples. Then, the spectral and chromatographic modifications of each studied ignitable liquid were discussed, proposing several chemical mechanisms that explain the new by-products produced and the gradual disappearance of the initial compounds. Hydrolysis, Fischer esterification and alkylation reactions are involved in the modification of esters, alcohols, ketones and aromatic compounds of the studied ignitable liquids. This information could be crucial for correctly identifying these accelerants. Additionally, an exploratory analysis revealed that some of the most altered ignitable liquid samples might be very similar with each other, which could have impact on casework

CONSTRUCCIÓN DE UN CUESTIONARIO SOBRE LA NECESIDAD DE FORMACIÓN EN COMUNICACIÓN NO-VERBAL EN EL GRADO EN EDUCACIÓN PRIMARIA

In a personalized education, as required by current education law, complete and effective communication between teachers and each student plays an important role. The more education that is needed, the more communication must be ensured. The higher educational quality is intended, the higher communicative quality is required. Hence, learning to communicate comprehensively and personally is a necessity in the study plans of Primary Education Degrees, as well as in Early Childhood Education and master's degrees that professionally qualify future teachers. This article describes the realization and validation of a questionnaire that allows analyzing the perception of students who finish their studies in the Degree of Primary Education regarding their knowledge of non-verbal elements, their importance and their training in non-verbal communication for the performance of teaching.En una educación personalizada, tal y como exige la ley educativa vigente, juega un papel importante la comunicación completa y eficaz entre el profesorado y cada alumno o alumna. Cuanta más educación se precise, mayor comunicación deberá asegurarse. Cuanta mayor calidad educativa se pretenda, mayor calidad comunicativa se requiere. De ahí que aprender a comunicarse integral y personalmente sea una necesidad en los planes de estudio de los Grados de Educación Primaria, como también en el de Educación Infantil y másteres que habiliten profesionalmente a futuros docentes. En el presente artículo se describe la realización y validación de un cuestionario que permita analizar la percepción del alumnado que finaliza sus estudios en el Grado de Educación Primaria respecto a su conocimiento de los elementos no-verbales, la importancia de estos y de su formación en comunicación no-verbal para el desempeño de la labor docente

Propuestas didácticas de carácter interdisciplinar para la enseñanza/Aprendizaje del espacio y el tiempo en la educación infantil

En este artículo se desarrollan propuestas didácticas de carácter interdisciplinar que el maestro de educación infantil puede aplicar en su práctica educativa para conseguir que niños y niñas interioricen las nociones de espacio y tiempo. Estas propuestas se enmarcan en el ámbito del conocimiento del entorno natural y social, que en esta etapa educativa no se configura como un área independiente. Se parte de la idea de que el propio cuerpo es el primer punto de referencia de la percepción y que desde la percepción del propio esquema corporal se llegará a dominar la percepción del espacio representativo. En la segunda parte, ampliamos el horizonte espacial e introducimos las nociones temporales, en base a la percepción que el niño tiene de los cambios que se producen en su entorno cercano, especialmente de los cambios rítmicos (rutinas en el día, cambios estacionales, cambios en la familia…). Por último, en la tercera parte, se plantea el descubrimiento, correcta percepción y comprensión por parte del niño, de un espacio más amplio: en la calle, el barrio, el pueblo o la ciudad. Cada uno de los tres apartados se acompaña de propuestas didácticas que permiten implementar y llevar a la práctica con facilidad, las argumentaciones teóricasIn this article we present interdisciplinary educational proposals that young children teachers could apply in their educational practice to ensure that children internalize the notions of space and time. These proposals concern the natural and the social environments, which in this level of education are not considered independent areas but one complex field. Each proposal contains specific activities with a theoretical basis which justifies them. We start in the first part from the concept that for human beings the body is the first benchmark of perception. From the perception of the body scheme itself, we finally acknowledge representative space. Then, in the second part, we expand the field and introduce temporal notions, taking into account the perception that children have of changes that occur in their immediate environment, especially recurrent changes (routines during the day, seasonal changes, within the family...). Finally, in the third part, we elaborate on the discovery, correct perception and understanding by the child, of a wider space: the street, the neighborhood, the town or cit

A proof-of-concept clinical trial using mesenchymal stem cells for the treatment of corneal epithelial stem cell deficiency

Producción CientíficaOcular stem cell transplantation derived from either autologous or allogeneic donor corneoscleral junction is a functional cell therapy to manage extensive and/or severe limbal stem cell deficiencies that lead to corneal epithelial failure. Mesenchymal stem cells have been properly tested in animal models of this ophthalmic pathology, but never in human eyes despite their potential advantages. We conducted a 6- to 12-month proof-of-concept, randomized, and double-masked pilot trial to test whether allogeneic bone marrow-derived mesenchymal stem cell transplantation (MSCT], n = 17) was as safe and as equally efficient as allogeneic cultivated limbal epithelial transplantation (CLET), (n = 11) to improve corneal epithelial damage due to limbal stem cell deficiency. Primary endpoints demanded combination of symptoms, signs, and the objective improvement of the epithelial phenotype in central cornea by in vivo confocal microscopy. This proof-of-concept trial showed that MSCT was as safe and efficacious as CLET. Global success at 6–12 months was 72.7%–77.8% for CLET cases and 76.5%–85.7% for MSCT cases (not significant differences). Central corneal epithelial phenotype improved in 71.4% and 66.7% of MSCT and CLET cases, respectively at 12 months (P = 1.000). There were no adverse events related to cell products. This trial suggests first evidence that MSCT facilitated improvement of a diseased corneal epithelium due to lack of its stem cells as efficiently as CLET. Consequently, not only CLET but also MSCT deserves more preclinical investigational resources before the favorable results of this proof-of-concept trial could be transformed into the larger numbers of the multicenter trials that would provide stronger evidence. (ClinicalTrials.gov number, NCT01562002.)Ministerio de Sanidad, Consumo y Bienestar Social (project SAS/2481/2009)Centro en Red de Medicina Regenerativa y Terapia Celular de Castilla y León (grant SAN 1178/200)Red de Terapia Celular TerCel (project RD12/0019/0036