Targeted analysis reveals alteration in pathway in 5p minus individuals

Cri du Chat or 5p minus (5p−) syndrome is characterized by a deletion located on the chromosome 5 short (−p) arm and has an incidence rate of 1 in 50,000 individuals worldwide. This disease manifests in disturbances across a range of systems biochemicals. Therefore, a targeted metabolomics analysis was evaluated in patients with 5p− syndrome to help unravel the biochemical changes that occur in this disease. Urine samples were collected from people of both sexes aged 1–38 years old and analyzed by ultra-performance liquid chromatography coupled to mass spectrometry. Student' statistical test, metabolomic pathway analysis and metabolite set enrichment analysis were applied to the data. Alterations of some amino acids and amine biogenics levels were found in Cri du Chat Syndrome individuals. The alteration of most of these metabolites is associated with energy recuperation and glycolysis. In general, we found the catabolism of some metabolic pathways to be affected in 5p− patients.     

Non-covalent interaction of benzonitrile with single-walled carbon nanotubes

We have studied the interaction of benzonitrile with as-prepared and purified single-walled carbon nanotubes (SWCNTs). As-prepared SWCNTs, when suspended in benzonitrile, lead to a red colored dispersion which contains fragments composed mostly of amorphous carbon and carbon-coated catalyst, thus suggesting that benzonitrile is a solvent that can be used as one step of the purification process. Optical spectroscopic data (infrared, Raman, absorption) showed that purified carbon nanotubes interact weakly with benzonitrile. These experimental results are confirmed by first principles calculations that predict a very weak adsorption process through π–π interaction instead of through the free electron pair of the nitrile.     

Fast LC–MS Electrospray Ionization for the Quantification of Digoxin in Human Plasma and Its Application to Bioequivalence Studies

A fast, sensitive and specific liquid chromatography-mass spectrometry method has been developed for quantification of digoxin in human plasma. The method was optimized to bioequivalence studies aiming higher sensitivity and selectivity than previously published methods, in addition to shorter run time allowing high-throughput sample analyses from volunteers. Chromatographic separation was achieved by an RP-18e column hyphenated to an API 5000 mass spectrometer system set at negative electrospray ionization and operating in the MRM mode. Calibration curve was linear over a wide range of concentration (50.0–6000.0 pg mL⁻¹), with the lower limit of quantification at 50.0 pg mL⁻¹ and without interfering peaks at the retention time of digoxin (2.09 min). Dexamethasone was used as internal standard and samples were cleaned up by liquid-liquid extraction obtaining a mean recovery of 73.8%. Validation results confirmed inter-batch accuracy (−8.66 to 5.78%), precision (4.1–10.6%) and stability, in accordance with the U.S. Food and Drug Administration and the Brazilian National Health Surveillance Agency guidelines. The developed analytical method could be successfully applied to a single oral dose (0.25 mg), one-way, randomized, two-sequence, crossover bioequivalence study validating, up to date, the fastest analysis and the most sensitive and specific method already published for digoxin quantification.     

Discrete time model and algorithms for container yard crane scheduling

Container terminal (CT) operations are often bottlenecked by slow YC (yard crane) movements. PM (prime mover) queues in front of the YCs are common. Hence, efficient YC scheduling to reduce the PM waiting time is critical in increasing a CT’s throughput. We develop an efficient model for YC scheduling by taking into account realistic operational constraints such as inter-crane interference, fixed YC separation distances and simultaneous container storage/retrievals. Among them, only inter-crane interference has ever been considered in the literature. The model requires far fewer integer variables than the literature by using bi-index decision variables. We show how the model can be solved quickly using heuristics and rolling-horizon algorithm, yielding close to optimal solutions in seconds. The solution quality and solution time are both better than the literature even with additional constraints considered. The proposed formulations and algorithms can be extended to other problems with time windows and space constraints.     

Novel stability criteria for uncertain delayed Cohen–Grossberg neural networks using discretized Lyapunov functional

This paper deals with the stability analysis of delayed uncertain Cohen–Grossberg neural networks (CGNN). The proposed methodology consists in obtaining new robust stability criteria formulated as linear matrix inequalities (LMIs) via the Lyapunov–Krasovskii theory. Particularly one stability criterion is derived from the selection of a parameter-dependent Lyapunov–Krasovskii functional, which allied with the Gu’s discretization technique and a simple strategy that decouples the system matrices from the functional matrices, assures a less conservative stability condition. Two computer simulations are presented to support the improved theoretical results.     

An atomistic simulation study of oxygen-vacancy migration in perovskite electrolytes based on LaGaO3

Abstract  Static lattice simulation techniques were used to calculate the energetic barriers for oxygen-vacancy migration in the perovskite-type oxide LaGaO₃ substituted with alkaline earth cations. The calculated migration energies are found to vary with the number and size of the substituting cations in the immediate neigbourhood of the migrating defect. It is argued that not only the size but also the charge of the cations constituting the saddle-point configuration play a role in determining the migration energy. Graphical abstract        

Development, validation and application of a SDME/GC-FID methodology for the multiresidue determination of organophosphate and pyrethroid pesticides in water

A single-drop microextraction (SDME) procedure was developed for the analysis of organophosphorus and pyrethroid pesticides in water by gas chromatography (GC) with flame ionization detection (GC-FID). The significant parameters that affect SDME performance, such as the selection of microextraction solvent, solvent volume, extraction time, and stirring rate, were studied and optimized using a tool screening factorial design. The limits of detection (LODs) in water for the four investigated compounds were between 0.3 and 3.0 μg L⁻¹, with relative standard deviations ranging from 7.7 to 18.8%. Linear response data were obtained in the concentration range of 0.9-6.0 μg L⁻¹ (λ-cyhalothrin), 3.0-60.0 μg L⁻¹ (methyl parathion), 9.0-60.0 μg L⁻¹ (ethion), and 9.0-30.0 μg L⁻¹ (permethrin), with correlation coefficients ranging from 0.9337 to 0.9977. The relative recoveries for the spiked water ranged from 73.0 to 104%. Environmental water samples (n = 26) were successfully analyzed using the proposed method and methyl parathion presented concentration up to 2.74 μg L⁻¹. The SDME method, coupled with GC-FID analysis, provided good precision, accuracy, and reproducibility over a wide linear range. Other highlights of the method include its ease of use and its requirement of only small volumes of both organic solvent and sample.     

A model for predicting the multiscale crack growth due to an impact in heterogeneous viscoelastic solids

A two-scale model for predicting the multiple crack growth in viscoelastic solids due to an impact is presented. The cracks are considered only at the local scale through the use of a micromechanical viscoelastic cohesive zone model. The multiscale model has been implemented in a finite-element code. In order to minimize the computation time, the local finite-element meshes are solved in parallel by multiple processors. An example problem is given in order to demonstrate the capabilities of the model. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 45, No. 2, pp. 211–222, March–April, 2009.     

Hyperbolic unit groups and quaternion algebras

We classify the quadratic extensions and the finite groups G for which the group ring [G] of G over the ring of integers of K has the property that the group of units of augmentation 1 is hyperbolic. We also construct units in the ℤ-order of the quaternion algebra , when it is a division algebra.