Selective Reagent Ion Mass Spectrometric Investigations of the Nitroanilines

This paper presents an investigation of proton and charge transfer reactions to 2-, 3- and 4-nitroanilines (C6H6N2O2) involving the reagent ions H3O+·(H2O)n (n=0, 1 and 2) and O2+, respectively, as a function of reduced electric field (60-240 Td), using Selective Reagent Ion-Time-of-Flight-Mass Spectrometry (SRI-ToF-MS). To aid in the interpretation of the H3O+·(H2O)n experimental data, the proton affinities and gas-phase basicities for the three nitroaniline isomers have been determined using density functional theory. These calculations show that proton transfer from both the H3O+ and H3O+·H2O reagent ions to the nitroanilines will be exoergic and hence efficient, with the reactions proceeding at the collisional rate. For proton transfer from H3O+ to the NO2 sites, the exoergicities are 171 kJ mol-1 (1.8 eV), 147 kJ mol-1 (1.5 eV) and 194 kJ mol-1 (2.0 eV) for 2-, 3- and 4-nitroanilines, respectively. Electron transfer from all three of the nitroanilines is also significantly exothermic by approximately 4 eV. Although a substantial transfer of energy occurs during the ion/molecule reactions, the processes are found to predominantly proceed via non-dissociative pathways over a large reduced electric field range. Only at relatively high reduced electric fields (>180 Td) is dissociative proton and charge transfer observed. Differences in fragment product ions and their intensities provide a means to distinguish the isomers, with proton transfer distinguishing 2-nitroaniline (2-NA) from 3- and 4-NA, and charge transfer distinguishing 4-NA from 2- and 3-NA, thereby providing a means to enhance selectivity using SRI-ToF-MS.(VLID)4826158Version of recor

Polarized laser light scattering applied to surface morphology characterization of epitaxial III–V semiconductor layers

11 pages.-- PACS: 68.35.Bs; 81.05.Ea; 81.15.Hi; 78.35.+c; 78.66.FdIn this paper, we analyze typical morphologies of epitaxial III–V semiconductor layers by using a polarized laser light scattering technique. Crosshatched topographies, which are developed during heteroepitaxial growth, are studied. A sample with an intentionally high density of oval defects is also explored to establish how the laser light scattering pattern is affected by the presence of these defects, which are unavoidable in the epitaxial layers grown by molecular beam epitaxy. The former topographies produce a scattered light pattern that is highly anisotropic, with the intensity concentrated along two preferential directions; the latter defects give rise to a fairly isotropic pattern. Employing a perturbation-theoretical model, whose applicability and consistency are explicitly demonstrated by our results, the surface power spectral density is retrieved from the angle-resolved light scattering experimental data. For the samples exhibiting crosshatched topography, the scattering measurements provide information that allows us to model the roughness of the surface in terms of two quasi-one-dimensional, anisotropic components, and one two-dimensional, isotropic, long-range background. The root mean square heights and the typical lateral distances between ridges are obtained in quantitative agreement with the values extracted from the atomic force microscopy measurements. For the sample presenting oval defects, we consider their contribution to the surface power spectral density by means of a simple model of randomly distributed particles on a surface, and we compare the resulting power spectral density with typical behavior found in the literature for good-morphology GaAs layers. With the help of the ex situ information thus obtained, we also discuss the implementation of the light scattering technique for in situ monitoring during epitaxial growth.The authors wish to acknowledge the Spanish CICYT for financial support under Project No. TIC96-1020-C02. M.U.G. thanks the Consejería de Educación y Cultura de la Comunidad de Madrid for financial support. J.A.S.-G. acknowledges financial support from the Spanish DGESIC Grant No. PB97-1221.Spanish CICYTConsejería de Educación y Cultura de la Comunidad de MadridPeer reviewe

Applications of Direct Injection Soft Chemical Ionisation-Mass Spectrometry for the Detection of Pre-blast Smokeless Powder Organic Additives

Analysis of smokeless powders is of interest from forensics and security perspectives. This article reports the detection of smokeless powder organic additives (in their pre-detonation condition), namely the stabiliser diphenylamine and its derivatives 2-nitrodiphenylamine and 4-nitrodiphenylamine, and the additives (used both as stabilisers and plasticisers) methyl centralite and ethyl centralite, by means of swab sampling followed by thermal desorption and direct injection soft chemical ionisation-mass spectrometry. Investigations on the product ions resulting from the reactions of the reagent ions H3O+ and O2+ with additives as a function of reduced electric field are reported. The method was comprehensively evaluated in terms of linearity, sensitivity and precision. For H3O+, the limits of detection (LoD) are in the range of 41-88 pg of additive, for which the accuracy varied between 1.5 and 3.2%, precision varied between 3.7 and 7.3% and linearity showed R20.9991. For O2+, LoD are in the range of 72 to 1.4 ng, with an accuracy of between 2.8 and 4.9% and a precision between 4.5 and 8.6% and R20.9914. The validated methodology was applied to the analysis of commercial pre-blast gun powders from different manufacturers.(VLID)4826148Accepted versio

An Update on Effort Estimation in Agile Software Development: A Systematic Literature Review

[EN] Software developers require effective effort estimation models to facilitate project planning. Although Usman et al. systematically reviewed and synthesized the effort estimation models and practices for Agile Software Development (ASD) in 2014, new evidence may provide new perspectives for researchers and practitioners. This article presents a systematic literature review that updates the Usman et al. study from 2014 to 2020 by analyzing the data extracted from 73 new papers. This analysis allowed us to identify six agile methods: Scrum, Xtreme Programming and four others, in all of which expert-based estimation methods continue to play an important role. This is particularly the case of Planning Poker, which is very closely related to the most frequently used size metric (story points) and the way in which software requirements are specified in ASD. There is also a remarkable trend toward studying techniques based on the intensive use of data. In this respect, although most of the data originate from single-company datasets, there is a significant increase in the use of cross-company data. With regard to cost factors, we applied the thematic analysis method. The use of team and project factors appears to be more frequent than the consideration of more technical factors, in accordance with agile principles. Finally, although accuracy is still a challenge, we identified that improvements have been made. On the one hand, an increasing number of papers showed acceptable accuracy values, although many continued to report inadequate results. On the other, almost 29% of the papers that reported the accuracy metric used reflected aspects concerning the validation of the models and 18% reported the effect size when comparing models.This work was supported by the Spanish Ministry of Science, Innovation and Universities through the Adapt@Cloud Project under Grant TIN2017-84550-R.Fernández-Diego, M.; Méndez, ER.; González-Ladrón-De-Guevara, F.; Abrahao Gonzales, SM.; Insfran, E. (2020). An Update on Effort Estimation in Agile Software Development: A Systematic Literature Review. IEEE Access. 8:166768-166800. https://doi.org/10.1109/ACCESS.2020.3021664S166768166800

Sensitivity and representativeness of One-Health surveillance for diseases of zoonotic potential at health facilities relative to household visits in rural Guatemala

Most human and animal disease notification systems are unintegrated and passive, resulting in underreporting. Active surveillance can complement passive efforts, but because they are resource-intensive, their attributes must be evaluated. We assessed the sensitivity and representativeness of One-Health surveillance conducted at health facilities compared to health facilities plus monthly household visits in three rural communities of Guatemala. From September 2017 to November 2018, we screened humans for acute diarrheal, febrile and respiratory infectious syndromes and canines, swine, equines and bovines for syndromic events or deaths. We estimated the relative sensitivity as the incidence rate ratio of detecting an event in health facility surveillance compared to household surveillance from Poisson models. We used interaction terms between the surveillance method and sociodemographic factors or time trends to assess effect modification as a measure of relative representativeness. We used generalized additive models with smoothing splines to model incidence over time by surveillance method. We randomized 216 households to health facility surveillance and 198 to health facility surveillance plus monthly household visits. Health facility surveillance alone was less sensitive than when combined with household surveillance by 0.42 (95% CI: 0.34, 0.53), 0.56 (95% CI: 0.39, 0.79), 0.02 (95% CI: 0.00, 0.10), 0.28 (95% CI: 0.15, 0.50) and 0.22 (95% CI: 0.03, 0.92) times for human acute infections, human severe acute infections, and deaths in canines, swine and equines, respectively. Health facility surveillance alone underrepresented Spanish speakers (interaction p-value = 0.0003) and persons in higher economic assets (interaction p-values = 0.0008). The trend in incidence over time was different between the two study groups, with a larger decrease in the group with household surveillance (all interaction p-values <0.10). Surveillance at health facilities under ascertains syndromes in humans and animals which leads to underestimation of the burden of zoonotic disease. The magnitude of under ascertainment was differentially by sociodemographic factors, yielding an unrepresentative sample of health events. However, it is less time-intensive, thus might be sustained over time longer than household surveillance. The choice between methodologies should be evaluated against surveillance goals and available resources

Reconstrucción de la precipitación en el noroeste de la península ibérica durante los últimos 500 años usando un espeleotema de cueva fría, España

Ponencia presentada en: XXXV Jornadas Científicas de la AME y el XIX Encuentro Hispano Luso de Meteorología celebrado en León, del 5 al 7 de marzo de 2018.Aquí presentamos un registro de alta resolución de una estalagmita de una cueva ubicada en el centro de la Cordillera Cantábrica sin ninguna influencia antropogénica y sin variabilidad estacional de CO2. Esta estalagmita de 500 años, con una cronología elaborada con el método U / Th y con una tasa de crecimiento que varía entre 100 y 200 μm / año, calculada con el modelo Bchron, nos proporciona información precisa de las condiciones climáticas cercanas a la cueva a la que pertenece

Proposal of a principle cum scale analytical framework for analyzing agroecological development projects

Because agroecology has different meanings, it may be used in an arbitrary and potentially abusive way when deployed by development cooperation actors conceiving “agroecology-based” development projects. To make the appropriation of agroecology more transparent, we first review the recent attempts in academia to clarify the concept and identify two main trends: a principle-based agroecology and a series of different agroecologies. Based on a critical assessment of these attempts, we then propose a new framework to program, implement and analyze agroecological development projects: it distinguishes different agroecologies with their corresponding categories of principles and their scales of intervention. Further, we argue in favor of a specific category of methodological principles.SCOPUS: ar.jinfo:eu-repo/semantics/publishe