Chemometric-Assisted Optimization of RP-HPLC Method for Determination of Some Bioflavonoids in Brassica oleracea Species and Their Antioxidative Activity

In the present work, the rapid RP-HPLC method with UV (DAD) detection for simultaneous quantification of bioflavonoids: quercetin, apigenin, catechin, epicatechin, kaempferol, and luteolin in Brassica oleracea species samples (cauliflower, broccoli, and Brussels sprouts) was developed with the aid of LC-Simulator (ACD Labs® suite) software. A series of extracts obtained with different extraction method were evaluated for antioxidant activity. The optimal conditions for separation and quantification were established after nine scouting runs entered to LC-Simulator software. The optimized separation was achieved on Hypersil GOLD aQ column with isocratic elution and mobile phase composition A:2 % acetic acid in water and B:acetonitrile in 91:9 (v/v %) ratio. The R _s values were in the range from 2.6 to 8.00, indicating good selectivity of the method. The obtained results generally show good agreement with published data. Low detection limits (0.02–0.055 μg/mL) were obtained with acceptable recoveries (90–109 %). Total time of analysis was less than 11 min; therefore, the proposed method represents significant improvement over existing methods. Extracts from Brassica vegetables, obtained using different extraction procedures, were studied for their radical scavenging effects. Scavenging of DPPH showed different kinetics at the beginning of the assay period and after 15 min from the initialization of reaction. Different kinetics suggested the presence of polymerized and/or less active antioxidants with different scavenging mechanisms for particular polyphenolic compounds.     

Novel SCN5A p.Val1667Asp Missense Variant Segregation and Characterization in a Family with Severe Brugada Syndrome and Multiple Sudden Deaths

Genetic testing in Brugada syndrome (BrS) is still not considered to be useful for clinical management of patients in the majority of cases, due to the current lack of understanding about the effect of specific variants. Additionally, family history of sudden death is generally not considered useful for arrhythmic risk stratification. We sought to demonstrate the usefulness of genetic testing and family history in diagnosis and risk stratification. The family history was collected for a proband who presented with a personal history of aborted cardiac arrest and in whom a novel variant in the SCN5A gene was found. Living family members underwent ajmaline testing, electrophysiological study, and genetic testing to determine genotype-phenotype segregation, if any. Patch-clamp experiments on transfected human embryonic kidney 293 cells enabled the functional characterization of the SCN5A novel variant in vitro. In this study, we provide crucial human data on the novel heterozygous variant {"type":"entrez-nucleotide","attrs":{"text":"NM_198056.2","term_id":"124518659","term_text":"NM_198056.2"}}NM_198056.2:c.5000T>A (p.Val1667Asp) in the SCN5A gene, and demonstrate its segregation with a severe form of BrS and multiple sudden deaths. Functional data revealed a loss of function of the protein affected by the variant. These results provide the first disease association with this variant and demonstrate the usefulness of genetic testing for diagnosis and risk stratification in certain patients. This study also demonstrates the usefulness of collecting the family history, which can assist in understanding the severity of the disease in certain situations and confirm the importance of the functional studies to distinguish between pathogenic mutations and harmless genetic variants.     

Dynamics of deuterium retention and sputtering of Li–C–O surfaces

Chemistry as well as sputtering and reflection dynamics of lithiated carbon material, bombarded by slow hydrogen atoms are studied. We present a realistic method for computational simulation of the dynamics of the polar Li–C–O–H material dynamics. It is based on an approximate, semi-empirical quantum mechanics of electrons and classical mechanics of nuclei. Results are validated qualitatively by comparison with experiments and with a first principle DFT computations. In particular, we explain observed details of the hydrogen bonding chemistry in lithiated carbon, showing that incoming hydrogen interacts preferably with Li-C rather than C structures.     

Effects of LDPC Code on the BER Performance of MPSK System with Imperfect Receiver Components over Rician Channels

In this letter, we study the influence of receiver imperfections on bit error rate (BER) degradations in detecting low‐density parity‐check coded multilevel phase‐shift keying signals transmitted over a Rician fading channel. Based on the analytical system model which we previously developed using Monte Carlo simulations, we determine the BER degradations caused by the simultaneous influences of stochastic phase error, quadrature error, in‐phase‐quadrature mismatch, and the fading severity.     

An Operational Model for Support of Integrated Watershed Management

This paper presents a computer simulation-based methodology for operational support of integrated water resources management. The methodology is based on the systems approach, and use of feedback to capture physical and socio-economic processes occurring within a watershed. The approach integrates well established simulation models of physical processes with simulation models that describe socio-economic processes. The proposed methodology is illustrated by the evaluation of risk and vulnerability to changing climatic and socio-economic conditions in the Upper Thames watershed (south-western Ontario, Canada).The model results indicate that flooding in the watershed will be more severe as a result of climate change, while low flows are expected to remain at their current level. The most significant socio-economic factor in the Upper Thames watershed is water availability, shown to become under climate change a limiting factor for future growth and development.     

Carrier Transport in High-Mobility III–V Quantum-Well Transistors and Performance Impact for High-Speed Low-Power Logic Applications

DC and high-frequency device characteristics of In_0.7Ga_0.3As and InSb quantum-well field-effect transistors (QWFETs) are measured and benchmarked against state-of- the-art strained silicon (Si) nMOSFET devices, all measured on the same test bench. Saturation current (I_on) gam of 20% is observed in the In_0.7Ga_0.3As QWFET over the strained Si nMOSFET at (V_g - V_t) = 0.3 V, V_ds = 0.5 V, and matched I_off, despite higher external resistance and large gate-to-channel thickness. To understand the gain in I_on, the effective carrier velocities (v_eff) near the source-end are extracted and it is observed that at constant (V_g - V_t) = 0.3 V and V_ds = 0.5 V, the v_eff of In_0.7Ga_0.3As and InSb QWFETs are 4-5times higher than that of strained silicon (Si) nMOSFETs due to the lower effective carrier mass in the QWFETs. The product of v_eff and charge density (n_s), which is a measure of "intrinsic" device characteristics, for the QWFETs is 50%-70% higher than strained Si at low-voltage operation despite lower ns in QWFETs. Calibrated simulations of In_0.7Ga_0.3As QWFETs with reduced gate-to-channel thickness and external resistance matched to the strained Si nMOSFET suggest that the higher v_eff will result in more than 80% I_on increase over strained Si nMOSFETs at V_ds = 0.5 V, (V_g - V_t) = 0.3 V, and matched I_off, thus showing promise for future high-speed and low-power logic applications.     

A method for transformation of the system fault tree and repair policies into equivalent state-space diagram

In this paper is presented the algorithm which automatically forms the state space diagram from the fault tree. Proposed algorithm is designed to minimize the number of states. This is achieved by grouping identical modules in one base event, by merging identical system states and without expanding those branches in the space diagram which can not eventually lead to the system failure. Second algorithm described adds transitions which represent repairs to the state-space diagram formed by the first algorithm. Diagram, which is generated by the above algorithms can be solved by any numerical method, giving reliability or availability of the system.     

Solution Equilibria between Aluminum(III) Ion and L-histidine or L-tyrosine

Toxic effects due to high aluminum body loads were observed in a number of conditions following ingestion of Al-containing antacids. Bio-availability of aluminum depends not only on the solubility of the ingested salt but also on the physico-chemical properties of the soluble Al complexes formed in body fluids. Amino acids may, upon interaction with Al-salts, form absorbable Al-complexes. Hence, complex formation equilibria between Al(3+) and either, L- histidine or L-tyrosine were studied by glass electrode potentiometric (0.1 mol/L LiCl ionic medium, 298 K), proton NMR and uv spectrophotometric measurements. Non linear least squares treatment of the potentiometric data indicates that in the concentration ranges: 0.5相似文献   

Neighborhood size selection in the k-nearest-neighbor rule using statistical confidence

The k-nearest-neighbor rule is one of the most attractive pattern classification algorithms. In practice, the choice of k is determined by the cross-validation method. In this work, we propose a new method for neighborhood size selection that is based on the concept of statistical confidence. We define the confidence associated with a decision that is made by the majority rule from a finite number of observations and use it as a criterion to determine the number of nearest neighbors needed. The new algorithm is tested on several real-world datasets and yields results comparable to the k-nearest-neighbor rule. However, in contrast to the k-nearest-neighbor rule that uses a fixed number of nearest neighbors throughout the feature space, our method locally adjusts the number of nearest neighbors until a satisfactory level of confidence is reached. In addition, the statistical confidence provides a natural way to balance the trade-off between the reject rate and the error rate by excluding patterns that have low confidence levels. We believe that this property of our method can be of great importance in applications where the confidence with which a decision is made is equally or more important than the overall error rate.