An Easy Method to Prepare D3 and C2-TATP Crystals

D3 and C2 TATP structures interconvert at room temperature. Herein, an easy method to isolate both conformers is shown that consists of multiple recrystallization steps using different solvent and heating to boiling. Spectroscopic and physical measurements, such as Raman spectroscopy, X-ray diffraction, and melting point analysis, showed that clear and opaque crystals, respectively, represent different conformations of TATP. Additionally, the transition energy between both conformers was estimated using the Raman shifts

Theoretical study of the humic acid interactions with Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations at DFT level of theory and PCM solvation model

In this paper, two models of humic acids, the Temple-Northeastern-Birmingham (TNB) and Kolla models, were studied. Also, the complexation reaction of the structures formed by the interaction of the TNB and Kolla models with Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, common in agricultural soils, was studied. These calculations were made for the complexes, at PM6 and DFT/LANL2DZ level of theory, both in vacuum and in aqueous medium. We found a strong affinity between Kolla and TNB models, and Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, influenced by the solvent that affected the interaction sites; the solvent increased the rate of reactivity and affinity for the cations in nucleophilic regions and decreased it in electrophilic regions of the structures. Calculations of molecular electronic potential, MEP and atomic charges, the local smoothness, Fukui functions and the HSAB principle adequately described the HA/cations interactions which were affected by the number of hydrogen bonds. The most reactive sites were the hydroxyl, phenolic, carbonyls oxygens and nitrogens at both vacuum and aqueous medium, especially carbonyl oxygens. These results are consistent with the properties of HA that make them attractive as components of agricultural soils

Verificación De La Asignación Vibracional Teórica De DADP Usando Marcaje Isotópico

This work deals with the comparison of the theoretical assignment of the DADP vibrational spectrum with the experimental displacements by isotopic labeling. For this, the DADP-C4 and DADP-C2 isotopomers were synthesized from acetone labeled isotopically in the methyl and the carbonyl carbon atoms, respectively. The acetone and DADP-isotopomer compounds were characterized using Raman and infrared spectroscopy. Theoretical assignments were taken from previous studies on the potential energy distribution of a vibrational mode, which provide an approach to the internal coordinates related to each band. The selective isotopic labeling allowed us to approach to the dependence of each band, because the energy of a molecular vibration also depends on the reciprocal mass of the atoms involved. In general, the results showed that some bands assigned experimentally do not coincide with the theoretical assignments by quantum mechanical simulations

Vibrational detection of acetaminophen in commercials tablets by ATR-FTIR spectroscopy and Chemometrics

Acetaminofén (AAP) es un ingrediente activo muy utilizado en muchas preparaciones farmacéuticas. AAP es un analgésico y un fármaco reductor de la fiebre. Generalmente, se utiliza para tratar muchas condiciones tales como dolor de cabeza, dolores musculares, artritis, dolor de espalda, dolores de muelas, resfriados y fiebres. Los métodos estándar más utilizados para la detección química de AAP se basan en técnicas de cromatografía y espectrofotometría, estos métodos generalmente implican una etapa de preparación de la muestra, mientras que los métodos basados en FTIR no. Por lo tanto, los métodos analíticos basados en espectroscopia IR (FTIR) son muy importantes para la industria farmacéutica y agencia policial, dado que permiten obtener de forma fácil y rápida información molecular de una compuesto químico que permite su detección. En un esfuerzo por lograr un procedimiento de identificación fiable para la determinación cualitativa de AAP en diferentes productos farmacéuticos, se propone un tratamiento quimiométrico adicional a los datos ATRFTIR. El método propuesto fue probado en muestras sólidas que contenían AAP. La estadística de rutina de análisis de componentes principales (PCA) produjo excelentes resultados. Los resultados muestran que el sensor multivariado es útil para la detección de AAP en los fármacos ensayados. El uso del método propuesto permite conocer si el fármaco está presente como producto deseado o si se trata de medicamentos falsificados.Acetaminophen (AAP) is active ingredient very used in many pharmaceutical preparations. AAP is a pain reliever and a fever reducer drug. Generally, it is used to treat many conditions such as headache, muscle aches, arthritis, backache, toothaches, colds, and fevers. Standard methods most used for AAP chemical detection are based on chromatography and spectrophotometry techniques, these methods generally imply a sample preparation step, while FTIR based methods do not. Hence, an analytical methods based on IR spectroscopy are very important for the pharmaceutical industry and law enforcement agency, given that allow obtain a way easy and fast molecular information for its detection. In effort for attaining a reliable identification procedure for qualitative determination of AAP in different pharmaceuticals product, an additional chemometrics treatment of ATR-FTIR data is proposed. The proposed method was tested on solid samples containing API. The statistical routine of principal component analysis (PCA) yielded excellent results. The results show that the multivariate sensor is useful for detection of AAP in the drugs tested. Using the proposed method allowed to know if drug is present as desired product or it is counterfeit drugs

Cognition and its relationship with endogenous and exogenous factors in engineering students

In this research, a relational study was carried out between student cognition with endogenous factors (student attitude and age) and exogenous (collegiate origin) in engineering students of the University of Cartagena. The project was carried out in three (3) phases where the survey allowed the desired information to be obtained from an estimated nine hundred sixty (960) students between 2014 and 2016. In the second phase, the instrument was used to collect the information, which was constituted the cognitive scale of the Self-Regulation Inventory for Learning (SRLI) and in the third phase, the independent endogenous and exogenous variables were crossed with the dependent one (student cognition), constructing the bar diagram of the relationship analysis; being possible to determine statistical significance with the attitude of the student to a level of confidence of 95% while with the age and collegial origin was not relevant

Estudio a través de espectroscopia infrarroja y termogravimetría del efecto de la temperatura en hidrotalcitas de níquel y aluminio

The synthesis and use of materials as hydrotalcites have a high impact on development of new materials and technological advances, applied in areas such as catalysis and environmental chemistry. An aspect of vital importance is the temperature of collapse of the HTLc structure, because from this fact depend the properties of solids obtained. In this work was studied the thermal behavior of nickel-aluminum hydrotalcite, and determined the Ea associated with the collapse and formation of NiO. It was observed that the greater interaction among carbonate ions and OH groups occurs at 250 °C, temperature at which the collapse of the HTLc structure occurs. The solid N0,75A0,25 requires less energy to collapse, which is due to the greater distances between the positive sheets. The solid N0,66A0,33 need more energy for the formation of NiO, which is due to higher content of Al3+, disfavoring the growth of the initial particles of NiO.Las hidrotalcitas tienen un alto impacto en el desarrollo de nuevos materiales y en avances tecnológicos en áreas como catálisis y química ambiental. Un aspecto de vital importancia es la temperatura del colapso de la estructura HTLc, ya que de esta dependen las propiedades de los sólidos obtenidos. En este trabajo se estudió el comportamiento térmico de hidrotalcitas de níquel-aluminio y se determinó la Ea asociada al colapso y formación de NiO. Se observó que la mayor interacción entre iones carbonato y grupos OH ocurre a 250 °C, temperatura en la cual desaparece la estructura HTLc. El sólido N0,75A0,25 requirió menos energía para que ocurriese el colapso, debido a la mayor distancia entre las láminas. El material N0,66A0,33 necesito más energía para que ocurriese la formación del óxido de níquel, lo que se debe a que el mayor contenido de Al3+, desfavorece el crecimiento de las partículas iniciales de NiO

A Fragmentation Mechanism Of Homemade Explosive TMDD Using DART-MS And Isotopic Labeling

A fragmentation mechanism and characterization for the first time using Direct Analysis in Real Time-Time of Flight-Mass Spectrometry (DART-TOF-MS) of the tetramethylene diperoxide dicarbamide (TMDD) compound were presented. The MS-spectrum may support other research about devices and detection in real scene. The mass spectrum of TMDD obtained using DART ionization in the positive-ion detection mode exhibited a strong peak at m/z 254 representing an ammonium adduct ([TMMD·NH4]+). There was another peak at m/z 237, which represented the protonated molecule ([TMDD·H]+) of TMDD. These two peaks corroborated the identity of the analyte. The DART-MS spectra of the TMDD-isotopomer successfully corroborated the respective molecular tails. The principal fragmentation residues also showed coherence according to the number of isotopically labeled atoms on the TMDD structure. In contrast with other organic peroxides analyzed by this technique, TMDD exhibited substantial fragmentation. The theoretical modeling results showed that the fragmentation mechanism of the TMDD ion adduct is strongly dependent of the TMDD ring flexibility and the hydrogen bonding formed between the nitrogen and oxygen atoms and the atmospheric proton

Chemical evaluation of by-products of the grape industry as potential agricultural fertilizers

The grape industry, specifically the wine industry, is generating by-products rich in nutrients, which are underutilized and often end up being polluters of the environment. These byproducts are the bagasse, the stem and the grape seed in a proportion of 20% of the grape industrialized, that is, more than 100,000 tons/year in the Serra Gaucha. The use of winemaking by-products in the production of raw materials is a pioneering activity in Brazil and possibly in the world. This study is a characterization of products generated by the composting of this rich material, in order to assess its nutrient availability and possible contaminants. Also, the by-product of wine production in this pioneering project in Serra Gaucha were used and studied. The analyzes were done on the by-products and raw materials used; in the final products of the BEIFORT® line, both organic and organic certified fertilizer, solids, and liquid organic fertilizers 867 and 645 AHF. Organic nutrients, macro and micronutrients, important nutrients for agriculture and contaminants were analyzed using appropriated analytical techniques. It was concluded that the byproducts of the grape industrialization have optimal levels of organic loads and a good amount of important mineral elements to plants. However, in the course of composting, the concentration of Cu and Cr increases in the final solid compost, limiting the possible organic certification. Liquid extracts, despite not having high concentrations of nutrients, present a minimum of elements considered pollutants. In the final products only the uncertified organic fertilizer showed concentrations of Zn, Cu and Cr above the allowed levels, however the mixtures of inputs solved the problem. In other Beifort® products, especially liquid products, the presence of contaminants is irrelevant and the organic loads and nutrients were satisfactory

Verification of the vibrational theoretical assignment of the DADP using isotopic labelling

This work deals with the comparison of the theoretical assignment of the DADP vibrational spectrum with the experimental displacements by isotopic labeling. For this, the DADP-C4 and DADP-C2 isotopomers were synthesized from acetone labeled isotopically in the methyl and the carbonyl carbon atoms, respectively. The acetone and DADP-isotopomer compounds were characterized using Raman and infrared spectroscopy. Theoretical assignments were taken from previous studies on the potential energy distribution of a vibrational mode, which provide an approach to the internal coordinates related to each band. The selective isotopic labeling allowed us to approach to the dependence of each band, because the energy of a molecular vibration also depends on the reciprocal mass of the atoms involved. In general, the results showed that some bands assigned experimentally do not coincide with the theoretical assignments by quantum mechanical simulations.Este trabajo trata sobre la comparación de la asignación teórica del espectro vibracional de DADP con los desplazamientos experimentales por marcación isotópica. Para ello, se sintetizaron los isotopómeros DADP-C4 y DADP-C2, los cuales son isotopómeros parcialmente marcados. DADP-C4 y DADP-C2 fueron sintetizados a partir de acetona marcada isotópicamente en los átomos de carbonos del grupo metilo y carbonilo, respectivamente. La acetona y los compuestos isotopómeros de DADP fueron caracterizados usando espectroscopia Raman e Infrarroja. Las asignaciones teóricas fueron tomadas de estudios previos sobre la distribución de energía potencial de un modo vibracional, el cual proporciona una aproximación a las coordenadas internas relacionadas con cada banda vibracional. La marcación isotópica selectiva nos permitió acercarnos a la dependencia de cada banda, debido a que, la energía de una vibración molecular depende también de la masa recíproca de los átomos involucrados. En general, los resultados mostraron que algunas bandas asignadas experimentalmente no coinciden con las asignaciones teóricas mediante simulaciones mecánicas cuánticas

Conditions of work and dermatitis in workers exposed to chemical risks by cement

This research was carried out in order to identify the working conditions in workers exposed to cement in a cement factory in the city of Cartagena. Through different tools it was possible to carry out the diagnosis of the working conditions and to identify the hazards to which the workers of the company are exposed when being in direct contact with the cement; in this way it was possible to know that the dermatitis that were manifesting the workers has its direct relation with this chemical and therefore to be able to establish those measures tending to ensure the complete state of health of the workers. The type of research carried out is descriptive-qualitative, the applied methodology used as a closed questions survey tool, it was obtained as a result that 70% of the respondents did not use personal protection elements when handling cement, so can say that there is a considerable number of people exposed, which increases the likelihood that they may suffer contact dermatitis, through this the different preventive measures for working and health conditions among the employees of the cement company were raised