Novel Technique For Determination Research Articles

Purge-assisted solid phase microextraction based on activated carbon as a new technique for determination of odorous compounds in drinking water samples

The purge and trap method is widely used to extract volatile organic compounds from aqueous samples, but this method is time-consuming and analytes are difficult to desorb. Compared to purge and trap, solid phase microextraction (SPME) can desorbs analytes easily and quickly by inserting the fiber into the injection site of a gas chromatograph. However, other studies have demonstrated that the purge and trap method has a lower detection limits than SPME. This research aims to improve the efficiency of SPME by coupling it with purging by N2, named purge assisted SPME or PSPME as a novel technique for determination and quantification of trace amounts of odorous compounds (geosmin and 2-methylisoborneol) from water samples. The results showed that the extraction efficiency of PSPME has increased more than five times compared to normal SPME. Also, the optimal extraction time has decreased from 30 min to about 10 min.

ESTIMATION OF GROSS-STRUCTURE PARAMETERS OF GIANT DIPOLE RESONANCE: 2. EXPERIMENTAL TESTING

Experimental testing of a novel technique for determination of width and maximum of excitation function of a photonuclear reaction with dominant giant dipole resonance is conducted. The method is based on measurement of normalized reaction yield in a thin target, overlapping entirely a flux of X-rays and on processing of data obtained with the use of a developed analytical model. For the checking of method, the nickel and molybdenum foils of natural isotopic composition were activated by bremsstrahlung radiation at four energies of the electron beam in the range 40…95 MeV. The obtained parameters of cross-section of the reference reactions 58Ni(γ,n)57Ni and 100Mo(γ,n)99Mo are in good agreement with those presented in the available databases.

A Novel Technique for Determination of Residual Direct-Current Voltage of Liquid Crystal Cells with Vertical and In-Plane Electric Fields

Generation of residual direct-current (DC) voltage (VrDC) induces serious image sticking of liquid crystal displays (LCDs). In this study, a novel technique to determine the VrDC of LC cells is proposed. We found that the VrDC could be determined from a current-voltage (I-V) curve obtained by the application of triangular voltage. In the case of a vertically aligned twisted nematic (VTN) mode LC cell, where a vertical electric field is applied, the I-V curve shows maximum and minimum current peaks owing to rotation of an LC director, and the VrDC is able to be determined from an average value of the two peaks. On the other hand, in the case of a fringe field switching (FFS) mode LC cell, where an in-plane (lateral) electric field is applied from comb electrodes, the current peaks derived from the rotation of the LC director do not appear. Therefore, we could not adopt the same way with that of the VTN mode LC cell. However, we found that there were two minimum current peaks derived from minimum capacitances of the FFS mode LC cell, and could determine the VrDC by using these two current peaks. The proposed technique would be useful for the evaluation of the VrDC of the LCDs, where the electric field is applied both vertically and laterally.

A novel method for quantifying periodicity and time delay in dynamic neural networks using unstable subaction potential threshold depolarizations.

Techniques to identify and correlate the propagation of electrical signals (like action potentials) along neural networks are well described, using multisite recordings. In these cases, the waveform of action potentials is usually relatively stable and discriminating relevant electrical signals straightforward. However, problems can arise when attempting to identify and correlate the propagation of signals when their waveforms are unstable (e.g., fluctuations in amplitude or time course). This makes correlation of the degree of synchronization and time lag between propagating electrical events across two or more recording sites problematic. Here, we present novel techniques for the determination of the periodicity of electrical signals at individual sites. When recording from two independent sites, we present novel analytical techniques for joint determination of periodicity and time delay. The techniques presented exploit properties of the cross-correlation function, rather than utilizing the time lag at which the cross-correlation function is maximized. The approach allows determination of directionality of the spread of excitation along a neural network based on measurements of the time delay between recording sites. This new method is particularly applicable to analysis of signals in other biological systems that have unstable characteristics in waveform that show dynamic variability.NEW & NOTEWORTHY The determination of frequency(s) at which two sources are synchronized, and relative time delay between them, is a fundamental problem for a wide a range of signal-processing applications. In this methodology paper, we present novel procedures for periodicity estimation for single time series and joint periodicity and time delay estimation for two time series. The methods use properties of the cross-correlation function rather than the cross-correlation function explicitly.

A novel technique for determination of the fructose, glucose and sucrose distribution in nectar from orchids by HPLC-ELSD

The dominant components in floral nectar is fructose, glucose and sucrose. The concentration and the ratio between the sugars are indicative for plant species and play an important part in the interplay between plants and pollinators. In this paper we present a novel HPLC-ELSD based analytical method for sugar characterization of nectar from orchids. Nectar was collected on Whatman No. 1 paper and preserved in the field by 70 v/v% ethanol. The analytical method had a linear range up to at least 3000 mg L−1 for all 3 sugars with a precision of 1.5–1.7%. Correlation coefficients were 0.9999 to 1.0000. The LOD of all sugars were 5–7 mg L−1 and the LOQ were 17–19 mg L−1. Field samples were stable for min. 7 weeks at −18 °C. The technique was applied to two species of Platanthera (Orchidaceae) in order to test whether species-related differences in sugar composition could be observed. No differences were found between the two species, which were sucrose-dominant (53.5–100%) though with high variation within species and between individual flowers.

Calculation of Pressure Loss Coefficients in Combining Flows of a Solar Collector using Artificial Neural Networks

The paper presents a novel technique for determination of loss coefficients due to pressure by use of artificial neural network (ANN) in tee junctions. Geometry and flow parameters are feed into ANN as the inputs for purpose of training the network. Efficacy of the network is demonstrated by comparison of the ANN and experimentally obtained pressure loss coefficients for combining flows in a Tee Junction. Reynolds numbers ranging from 200 to 14000 and discharge ratios varying from minimum to maximum flow for calculation of pressure loss coefficients have been used. Pressure loss coefficients calculated using ANN is compared to the models from literature used in junction flows. The results achieved after the application of ANN agrees reasonably to the experimental values.

Optimal feature selection from fNIRS signals using genetic algorithms for BCI

In this paper, a novel technique for determination of the optimal feature combinations and, thereby, acquisition of the maximum classification performance for a functional near-infrared spectroscopy (fNIRS)-based brain-computer interface (BCI), is proposed. After obtaining motor-imagery and rest signals from the motor cortex, filtering is applied to remove the physiological noises. Six features (signal slope, signal mean, signal variance, signal peak, signal kurtosis and signal skewness) are then extracted from the oxygenated hemoglobin (HbO). Afterwards, the hybrid genetic algorithm (GA)-support vector machine (SVM) is applied in order to determine and classify 2- and 3-feature combinations across all subjects. The SVM classifier is applied to classify motor imagery versus rest. Moreover, four time windows (0–20s, 0–10s, 11–20s and 6–15s) are selected, and the hybrid GA-SVM is applied in order to extract the optimal 2- and 3-feature combinations. In the present study, the 11–20s time window showed significantly higher classification accuracies – the minimum accuracy was 91% – than did the other time windows (p<0.05). The proposed hybrid GA-SVM technique, by selecting optimal feature combinations for an fNIRS-based BCI, shows positive classification-performance-enhancing results.

A Novel Technique for Determination of the Onset of Alkane Induced Asphaltene Precipitation Using Accurate Density Measurements

Onset of asphaltene precipitation is the key parameter in dealing with asphaltene problems because it is the starting point of the asphaltene separation from the solution. In this study, a new technique is provided based on the experimental observations for the determination of the onset of asphaltene precipitation using accurate density measurements of the crude oils upon titration with precipitating agents like n-alkanes. Moreover, density measurements have been conducted for three different crude oils diluted with different ratios of precipitating agents, i.e. n-pentane, n-hexane, and n-heptane. The experimental results confirmed that, as it was expected, the density showed a decreasing trend as the dilution ratio increased, except at one point, at which the density increased with raising dilution ratio; this corresponded to the onset of asphaltene precipitation. For all the crude oils used, a sample diluted with a non-precipitating solvent (toluene) was also used as a reference system, its densities were measured upon titration with toluene, and the results were used for comparison with the other systems diluted with precipitating solvents. The measured onsets of asphaltene precipitation using this technique were confirmed with the onsets obtained by using interfacial tension approach.

A Novel Technique for Determination of the Onset of Asphaltene Precipitation Using Accurate Density Measurements

A Novel Technique for Determination of the Onset of Asphaltene Precipitation Using Accurate Density Measurements

Refractive-index measurement and inverse correction using optical coherence tomography.

We describe a novel technique for determination of the refractive index of hard biological tissue as well as nonopaque technical samples based on optical coherence tomography (OCT). Our method relies on an inverse refractive-index correction (I-RIC), which matches a measured feature geometry distorted due to refractive-index boundaries to its real geometry. For known feature geometry, the refractive index can be determined with high precision from the best match between the distorted and corrected images. We provide experimental data for refractive-index measurements on a polymethylmethacrylate (PMMA) and on an ex vivo porcine cranial-bone, which are compared to reference measurements and previously published data. Our method is potentially capable of in vivo measurements on rigid biological tissue such as bone as, for example, is required to improve guidance in robot-aided surgical interventions and also for retrieving complex refractive-index profiles of compound materials.

A novel technique for determination of two dimensional signal-to-noise ratio improvement factor of an antiscatter grid in digital radiography

Purpose: to present a new and simplified method for pixel-wise determination of the signal-to-noise ratio improvement factor KSNR of an antiscatter grid, when used with a digital imaging system. The method was based on approximations of published formulas. The simplified estimate of K2SNR may be used as a decision tool for whether or not to use an antiscatter grid.Methods: the primary transmission of the grid Tp was determined with and without a phantom present using a pattern of beam stops. The Bucky factor B was measured with and without a phantom present. Hence K2SNR maps were created based on Tp and B. A formula was developed to calculate K2SNR from the measured Bs without using the measured Tp. The formula was applied on two exposures of anthropomorphic phantoms, adult legs and baby chest, and on two homogeneous poly[methyl methacrylate] (PMMA) phantoms, 5 cm and 10 cm thick. The results from anthropomorphic phantoms were compared to those based on the beam stop method. The results for the PMMA-phantoms were compared to a study that used a contrast-detail phantom.Results: 2D maps of K2SNR over the entire adult legs and baby chest phantoms were created. The maps indicate that it is advantageous to use the antiscatter grid for imaging of the adult legs. For baby chest imaging the antiscatter grid is not recommended if only the lung regions are of interest.The K2SNR maps based on the new method correspond to those from the beam stop method, and the K2SNR from the homogenous phantoms arising from two different approaches also agreed well with each other.Conclusion: a method to measure 2D K2SNR associated with grid use in digital radiography system was developed and validated. The proposed method requires four exposures and use of a simple formula. It is fast and provides adequate estimates for K2SNR.

A Novel Technique for Determination of Flow Characteristics of Blast Furnace Slag

A study of flow characteristics of blast furnace slag helps determine its softening and flow (liquid-mobility) temperatures. The slag with a narrow difference between the two temperatures is termed a “Short Slag”. Its formation ensures higher rates of slag-metal reactions with the trickle of the slag soon after its formation exposing fresh mass for faster reactions, the trickling slag, creating fresh interfaces facilitating slag-metal exchanges. In the present work, a novel technique is adopted to determine the flow characteristics of blast furnace slag obtained from different industrial blast furnaces. It is seen that the results so obtained agree very closely with the values obtained from adopting conventional methods of determining the liquidus temperature using “slag atlas”. It is observed that under the range of compositions studied a high C/S ratio combined with a high MgO content in the slag is beneficial to the B.F. process as it renders a “short slag”.

Novel Technique for Determination of Actual Pixel Size in Dense Arrays of Infrared Detectors

A novel technique is proposed for determining the actual pixel size in dense arrays of infrared detectors. The technique is based on probing individual pixels in an array and analyzing the parasitic bipolar transistor formed between them to determine the lateral diffusion width and, hence, the actual pixel diameter. The actual pixel diameter can then be used to separate the area-dependent dark current from the periphery-dependent dark current. The result shows that, in the present arrays, the dark current is dominated by the periphery current, unless the pixels are so close to each other that their depletion regions overlap.

Two Novel Techniques for Determination of Polysaccharide Cross-Links Show that Crh1p and Crh2p Attach Chitin to both β(1-6)- and β(1-3)Glucan in the Saccharomyces cerevisiae Cell Wall

Previous work, using solubilization of yeast cell walls by carboxymethylation, before or after digestion with beta(1-3)- or beta(1-6)glucanase, followed by size chromatography, showed that the transglycosylases Crh1p and Crh2p/Utr2p were redundantly required for the attachment of chitin to beta(1-6)glucan. With this technique, crh1Delta crh2Delta mutants still appeared to contain a substantial percentage of chitin linked to beta(1-3)glucan. Two novel procedures have now been developed for the analysis of polysaccharide cross-links in the cell wall. One is based on the affinity of curdlan, a beta(1-3)glucan, for beta(1-3)glucan chains in carboxymethylated cell walls. The other consists of in situ deacetylation of cell wall chitin, generating chitosan, which can be extracted with acetic acid, either directly (free chitosan) or after digestion with different glucanases (bound chitosan). Both methodologies indicated that all of the chitin in crh1Delta crh2Delta strains is free. Reexamination of the previously used procedure revealed that the beta(1-3)glucanase preparation used (zymolyase) is contaminated with a small amount of endochitinase, which caused erroneous results with the double mutant. After removing the chitinase from the zymolyase, all three procedures gave coincident results. Therefore, Crh1p and Crh2p catalyze the transfer of chitin to both beta(1-3)- and beta(1-6)glucan, and the biosynthetic mechanism for all chitin cross-links in the cell wall has been established.

Photon Collection Efficiency of Fluorescent Solar Collectors

Photon collection efficiency of fluorescent collectors is examined experimentally and by modelling, with a view to assess the potential of this attractive solar energy technology. The edge fluorescence of single dye collectors based on Rhodamine 6G and Coumarin 540A, manufactured by a simple fabrication technique, is investigated in detail. A novel technique for determination of the collection efficiency is presented based on the traditional model of fluorescent collectors but extended to allow spectral analysis. We show that these results agree well with direct solar cell measurements. General conclusions are presented about fundamental loss mechanisms and about the role of re-absorption of fluorescent light. It is shown that substantial improvements in collector efficiency can be made with the use of photonic fluorescence confinement rather than by total internal reflection.

Comments of the paper ‘Capacity intermittent titration technique (CITT). A novel technique for determination of Li+ solid diffusion coefficient of LiMn2O4’ [X.-C. Tang, X.-W. Song, P.-Z. Shen, D.-Z. Jia, Electrochim. Acta 50 (2005) 5581–5587

Abstract The article by Tang et al., which was published recently [Electrochim. Acta, Electrochim. Acta 50 (2005) 5581–5587], proposed a novel technique for the determination of diffusion coefficients of intercalated species in host materials. The capacity intermittent titration technique (CITT) is an extension of the ratio of potentiostatic-to-galvanostatic charge (RPG) technique developed initially by the same authors. By the CITT, the Li + solid-state diffusion coefficient within LiMn 2 O 4 was determined by these authors at different voltages and different galvanostatic-charge currents. In these comments, the ratio of potentiostatic-to-galvanostatic charge is reexamined by taking finite charge-transfer kinetics at the interface and Ohmic drop into consideration. The measurement error of diffusion coefficients evaluated by CITT while using the approximation of infinitely fast charge-transfer kinetics is predicted quantitatively.

Positioning Membrane Proteins by Novel Protein Engineering and Biophysical Approaches

Membrane proteins are unique, in that they can function properly only when they are bound to cellular membranes in a distinct manner. Therefore, positioning of membrane proteins with respect to the membrane is required in addition to the three-dimensional structures in order to understand their detailed molecular mechanisms. Atomic-resolution structures of membrane proteins that have been determined to date provide the atom coordinates in arbitrary coordinate systems with no relation to the membrane and therefore provide little or no information on how the protein would interact with the membrane. This is especially true for peripheral membrane proteins, because they, unlike integral proteins, are devoid of well-defined hydrophobic transmembrane domains. Here, we present a novel technique for determination of the configuration of a protein-membrane complex that involves protein ligation, segmental isotope labeling, polarized infrared spectroscopy, membrane depth-dependent fluorescence quenching, and analytical geometry algorithms. We have applied this approach to determine the structure of a membrane-bound phospholipase A2. Our results provide an unprecedented structure of a membrane-bound protein in which the z-coordinate of each atom is the distance from the membrane center and therefore allows precise location of each amino acid relative to the membrane. Given the functional significance of the orientation and location of membrane-bound proteins with respect to the membrane, we propose to specify this structural feature as the "quinary" structure of membrane proteins.

Capacity intermittent titration technique (CITT): A novel technique for determination of Li+ solid diffusion coefficient of LiMn2O4

The capacity intermittent titration technique (CITT) has been developed on basis of the ratio of the potentio-charge capacity to the galvano-charge capacity (RPG) method to determine continuously the solid diffusion coefficient D of the intercalary species within insertion-host materials. In experiment, CITT is based on the capacity response of galvano–potentio-charge in a small voltage region. In theory, CITT is based on the linear equations of D versus q (value of RPG) in different range of q. By the CITT, the Li+ solid diffusion coefficients within LiMn2O4 have been determined at different voltages and different galvano-charge currents. Results shows that the order of magnitude of D varies non-linearly with the “W” shape from 10−9 to 10−11 cm2 s−1 in the voltage range from 3.3 to 4.3 V. The galvano-charge current also leads to the error due to the semi-conductive character of LiMn2O4, and the maximal error may reach as much as one order of magnitude. In addition, the main approximations that lead to errors of CITT are qualitatively analyzed.

A novel technique for determination of histories of SIF distributions along 3D crack fronts of a body subjected to thermal shock

AbstractThe thermal weight function (TWF) is dependent only on the crack configuration and body geometry, and is independent of temperature fields. TWF is independent of time during thermal shock, so the whole variation of transient stress intensity factors (SIFs) can be directly calculated through integration of products of TWF and transient temperatures and temperature gradients. The basic equation for the 3D TWF method for Mode I is derived. Then a novel technique, referred to as the multiple virtual crack extension (MVCE) technique, is proposed to solve the basic equations in the 3D TWF method. The specially selected linearly independent VCE modes are directly used as shape functions for the interpolation of unknown SIFs. The coefficient matrix of the final system of equations is a triple‐diagonal matrix and the values of the coefficients on the main diagonal are usually large. The system of equations has good numerical properties. The number of linearly independent VCE modes which can be introduced in a problem is unlimited. The complex situations that the SIFs vary dramatically along the crack fronts can be numerically well simulated by the MVCE technique. Examples show that the scheme is of very high efficiency and of good accuracy. The results show that the histories of SIF distributions along 3D crack fronts are very complex. In order to understand the behaviour of 3D cracks correctly it should be calculated in detail. Copyright © 2004 John Wiley &amp; Sons, Ltd.

A Novel Technique for Determination of Vapor Transmission Rate through Textiles

A novel technique for precise, accurate and fast determination of vapor transmission rate through textiles is discussed. Vapor at a constant pressure is maintained on one side of the textile and the increase in pressure of the vapor on the other side is measured. The technique was used to investigate two textiles. The vapor permeabilityof the textiles is almost five orders of magnitude lower than their air permeability. The air permeability of the textiles are identical, however, they show strong differences in vapor permeability.