Design of a virtual sensor data array for the analysis of RDX, HMX and DMNB using metal-doped screen printed electrodes and chemometric analysis

The detection of explosive substances is a subject of high importance in several areas including environmental health, de-mining efforts (land and sea) and security and defence against terrorist activity. The use of electrochemical methods for the detection of these substances has increased in recent years but still is quite restricted to the most common explosives. The electrochemical detection of explosive nitroamines and taggant substances in solution using a virtual sensor array of metal-doped screen printed electrodes and differential pulse voltammetry was achieved. The multiple sets of voltammetric data from the different electrodic systems using Differential Pulse Voltammetry (DPV) were integrated using multivariate analysis (PCA, NIPALS and LDA) and matched with known substances present in explosives. These combinations created a mathematical array which separated the explosives, even if the electrochemical information is buried or mixed with the background noise. Two explosive substances: octogen (HMX- 1,3,5-Trinitroperhydro-1,3,5-triazine) and cyclonite (RDX- Hexahydro-1,3,5-trinitro-1,3,5-triazine) and a taggant agent 2,3-dimethyl-2,3-dinitrobutane (DMNB) were subjected to electrochemical analysis using a solid carbon- based screen printed electrode modified with silver, gold and platinum in aqueous solutions. Keywords

Chemometric study on the forensic discrimination of soil types using their infrared spectral characteristics

Soil has been utilized in criminal investigations for some time because of its prevalence and transferability. It is usually the physical characteristics that are studied, however the research carried out here aims to make use of the chemical profile of soil samples. The research we are presenting in this work used sieved (2mm) soil samples taken from the top soil layer (about 10cm) that were then analysed using mid infrared spectroscopy. The spectra obtained were pre-treated and then input into two chemometric classification tools: Nonlinear iterative partial least squares followed by linear discriminant analysis (NIPALS-LDA) and partial least squares discriminant analysis (PLS-DA). The models produced show that it is possible to discriminate between soil samples from different land use types and both approaches are comparable in performance. NIPALS-LDA performs much better than PLS-DA in classifying samples to locatio

The function of the respiratory supercomplexes: the plasticity model

Mitochondria are important organelles not only as efficient ATP generators but also in controlling and regulating many cellular processes. Mitochondria are dynamic compartments that rearrange under stress response and changes in food availability or oxygen concentrations. The mitochondrial electron transport chain parallels these rearrangements to achieve an optimum performance and therefore requires a plastic organization within the inner mitochondrial membrane. This consists in a balanced distribution between free respiratory complexes and supercomplexes. The mechanisms by which the distribution and organization of supercomplexes can be adjusted to the needs of the cells are still poorly understood. The aim of this review is to focus on the functional role of the respiratory supercomplexes and its relevance in physiology. This article is part of a Special Issue entitled: Dynamic and ultrastructure of bioenergetic membranes and their components.This study was supported by grants from the Ministerio de Ciencia e Innovación (SAF2012-32776 & CSD200700020); the Comunidad de Madrid (CAM/API1009); and the Marie Curie Career Integration Grant (UEO/MCA1108). RA-P is an investigator of the Ramon y Cajal research program from the Ministerio de Economía y Competitividad. The CNIC is supported by the Ministerio de Economía y Competitividad and the Pro-CNIC Foundation.S

La competitividad de la producción agrícola en México, un análisis regional

This research was carried out in the Rural Development District 092 located in Morelia, Michoacan for the fall winter cycle period 2010 - 2011. It consisted on the analysis of profitability of improved seed varieties, under the system gravity irrigation, improved seed and fertilized - conservation tillage. The varieties concerned were Triunfo F2004, F2007 Josecha, Maya S2007, Monarch F2007, F2007 Northern, Altiplano S2007, F2007 and Salamanca Roelfs S-75. For the analysis of private profitability, eight varieties had positive gain, the most profitable variety was monarch, followed by the variety Josecha, Maya, Salamanca, Northern, Roelfs, Triumph and Altiplano. About the cost structure of production, fertilizers were the most significant. When estimating profitability, the eight varieties exhibited comparative advantage, in order of importance, the first one was the variety Monarch, followed by Josecha, Maya, Salamanca, Northern, Roelfs, Triumph and Altiplano. The effects of macroeconomic policy and sectoral policy benefit both the producer income, and decreased cost via inputs. It is recommended to apply new technology to conduct better use of irrigation water, improve marketing schemes for wheat, seek economies in the purchase of nitrogen fertilizers

The forensic analysis of soil by FTIR with multivariate analysis

Over the past few years more and more studies have been carried out in an attempt to utilize chemical profiles of soil using a wide variety of analytical methods. The value of soil as evidence rests with its prevalence at crime scenes and its transferability between the scene and the criminal. This can be of value for comparison if the scene of crime is known, but could also be so in the identification of a scene. The main basis for the comparison of sites to determine provenance is that soils vary from one place to another. The aim of this work is to find simple methods to identify soil provenance based on FTIR and multivariate analysi

Electrochemical reduction of carbamazepine in ethanol and water solutions using a glassy carbon electrode

The electrochemical reduction of carbamazepine in ethanol and water using a glassy carbon electrode has been studied. In all experimental conditions of scan rate and concentration of carbamazepine an irreversible cathodic wave was observed by cyclic voltammetry (CV). Electrochemical parameters and a plausible EqC mechanism have been reported from the electrochemical measurements and digital simulation. The values of thermodynamic E1/2 were correlated with solvent polarity parameters that it can be interesting for biological, pharmaceutical and forensic purposes. Limits of Detection (LOD) for DPV are 1.1 and 9.0 g/mL (4.65x10-6 and 3.81x10-5 M) in ethanol and water, respectively. The precision and recoveries obtained for tablets and plasma samples showed that the method could be successfully used for analysis

Physiological and molecular studies on the akinete differentiation of filamentous cyanobacteria

Akinetes are spore-like cells of filamentous cyanobacteria that allow these organisms to survive long periods of unfavourable conditions. The akinete differentiation and germination processes were studied in detail in two model species of cyanobacterial cell differentiation, the planktonic freshwater Anabaena variabilis ATCC 29413 and the terrestrial or symbiotic Nostoc punctiforme ATCC 29133. The best trigger of akinete differentiation of A. variabilis was low light, while of N. punctiforme was phosphate starvation. Akinetes differed from vegetative cells by their larger size, different cell morphology, and the presence of a large number of intracellular granules. The akinete envelopes of both strains were composed by the same glycolipids as heterocysts and by an exopolysaccharide layer. Also, an unknown and new lipid was detected in lipid extracts of A. variabilis akinetes. During akinete development the storage compounds cyanophycin, glycogen and lipid droplets transiently increased, and the photosynthesis and respiration activities decreased. In both strains, germination was an asynchronous process triggered by light. Fast cell divisions occurred inside of the akinetes envelope and did not need endogenous carbon or nitrogen resources but a functional photosystem to complete the process. Unusual fast heterocyst differentiation was observed during akinete germination in A. variabilis. Fast cell divisions and heterocysts differentiation during germination could have been supported by the high DNA content in akinetes. In the end of the germination process, the akinete envelope was opened (A. variabilis) or partially degraded (N. punctiforme) allowing the emergence of the short filament formed. At this point, the photosynthesis and respiration rates were similar to a vegetative cells culture. Focusing on the specific modulation of the cell wall and cell envelope, proteins were identified that are differentially expressed in akinetes or where shown to be involved in cell differentiation in N. punctiforme. One mutant was created in the ΔAva_2312 gene of A. variabilis encoding a protein with putative function associated to cell wall proteins and characterized. This mutant showed a severe filament dystrophy and it was not able to differentiate heterocysts and to grow without a combined nitrogen source. In addition, a thicker peptidoglycan with more non-crosslinked peptides residues was observed in the septum. Finally, this mutant differentiated akinete-like cells lacking a lipid envelope. Mutants in genes encoding the cell wall lytic enzymes ΔamiC1 and ΔamiC2 of A. variabilis were also created and characterized in this study. Both mutant strains showed filaments of longer vegetative cells, which differentiated non-functional heterocysts and akinete like-cells. The heterocysts with aberrant morphology showed an abnormal or no deposition of glycolipids, absence of cyanophycin polar bodies and accumulation of glycogen characteristic for a phenotype with hampered N2 fixation. Accumulation of a thicker peptidoglycan in the septum between the heterocyst and the vegetative cells was observed in both mutant strains. Moreover, ΔamiC1 and ΔamiC2 mutants formed akinete like-cells with rounded-shape, irregular or missing lipid envelope than in wild type. In this study, clear differences in the metabolic and morphological adaptation mechanisms of akinetes from two important cyanobacterial species were found. For the first time a detailed characterization of the germination process of these species was presented. The results paved the way for further genetic and functional studies of akinete differentiation and germination in these species. In fact, three new mutants in cell wall genes involved in akinete development were characterized showing the relevance of the cell wall proteins in cell differentiation

An experimental and modelling exploration of the host-sanction hypothesis in legume-rhizobia mutualism

Despite the importance of mutualism as a key ecological process, its persistence in nature is difficult to explain since the existence of exploitative, 'cheating' partners that could erode the interaction is common. By analogy with the proposed policing strategy stabilizing intraspecific cooperation, host sanctions against non N2 fixing, cheating symbionts have been proposed as a force stabilizing mutualism in legume-Rhizobium symbiosis. Following this proposal, penalizations would include decreased nodular rhizobial viability and/or early nodule senescence in nodules occupied by cheating rhizobia. In this work, we analyze the stability of Rhizobium-legume symbiosis when "cheating" strains are present, using an experimental and modelling approach. We used split-root experiments with soybean plants inoculated with two rhizobial strains, a cooperative, normal N2 fixing strain and an isogenic non-fixing, “perfect” cheating mutant derivative that lacks nitrogenase activity but has the same nodulation abilities inoculated to split-root plants. We found no experimental evidence of functioning plant host sanctions to cheater rhizobia based on nodular rhizobia viability and nodule senescence and maturity molecular markers. Based on these experiments, we developed a population dynamic model with and without the inclusion of plant host sanctions. We show that plant populations persist in spite of the presence of cheating rhizobia without the need of incorporating any sanction against the cheater populations in the model, under the realistic assumption that plants can at least get some amount of fixed N2 from the effectively mutualistic rhizobia occupying some nodules. Inclusion of plant sanctions merely reduces the time needed for reaching plant population equilibrium and leads to the unrealistic effect of ultimate extinction of cheater strains in soil. Our simulation results are in agreement with increasing experimental evidence and theoretical work showing that mutualisms can persist or even improve in presence of cheating partners

Protein Phosphorylation and Prevention of Cytochrome Oxidase Inhibition by ATP: Coupled Mechanisms of Energy Metabolism Regulation

SummaryRapid regulation of oxidative phosphorylation is crucial for mitochondrial adaptation to swift changes in fuels availability and energy demands. An intramitochondrial signaling pathway regulates cytochrome oxidase (COX), the terminal enzyme of the respiratory chain, through reversible phosphorylation. We find that PKA-mediated phosphorylation of a COX subunit dictates mammalian mitochondrial energy fluxes and identify the specific residue (S58) of COX subunit IV-1 (COXIV-1) that is involved in this mechanism of metabolic regulation. Using protein mutagenesis, molecular dynamics simulations, and induced fit docking, we show that mitochondrial energy metabolism regulation by phosphorylation of COXIV-1 is coupled with prevention of COX allosteric inhibition by ATP. This regulatory mechanism is essential for efficient oxidative metabolism and cell survival. We propose that S58 COXIV-1 phosphorylation has evolved as a metabolic switch that allows mammalian mitochondria to rapidly toggle between energy utilization and energy storage