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Biodiesel is a renewable energy source that can be employed as an alternative fuel to fossil diesel. Monitoring samples in terms of fatty acid methyl esters (FAMEs) content using gas chromatography (GC) is a useful way to evaluate the quality of biodiesel produced. Fast GC can be used to reduce the time of analysis and consequently the costs, even though the equipment required for this may be expensive. Therefore, we developed and validated a Fast GC-response factor (Fast-GCRF) methodology using a low-priced nonpolar column, flame ionization detection (FID) and a standard chromatograph usually destined for conventional GC separations. The method was validated and applied to the quantification of FAMEs produced from various raw materials (soybean, cottonseed, canola, coconut, palm, sesame, sunflower, castor, corn, macauba, almond, peanut, chia seeds, residual frying oils, and chicken fat), being both selective and robust even when subjected to changes in sample preparation. The Fast GCRF method presented respective maximum relative standard deviation (RSD) values for instrumental precision, repeatability, and intermediate precision of 2.3 %, 3.6 %, and 2.8 %. When compared to conventional GC methodologies, accurate results with high degrees of agreement were obtained using the Fast-GCRF method, within an at least four times shorter analysis time. • Fast GC quantification of total biodiesel FAMEs produced from fifteen feedstocks. • Lower-cost instrumentation than usual fast GC FAMEs analysis. • Fast-GCRF proved to be accurate via recovery tests and method comparison. • Total analysis time at least four times shorter than the methods used as reference. [ABSTRACT FROM AUTHOR]

Highlights • Universal detectors that can detect all types of compounds and give uniform response are highly desirable. • Reviewed commonly used detectors in analytical characterization, with the focuses on the "universal" features. • UV, RI, ELSD, CAD, CLND, FID, VUV, MS, NMR, etc. and hyphenated detections are reviewed. Abstract It is highly desirable to have a universal detector that can detect all types of compounds and give a uniform response regardless of the physiochemical properties of the compounds. With such a universal detector, all components in a sample can be accurately quantified without the need for individual standards. This is especially needed for the characterization of unknowns and for non-targeted analysis, or for samples that have no isolated standards available for each component. Over the years, much effort has been put into seeking a universal detection technology. In this review, we discuss the commonly used detectors for analytical characterization, including UV, RI, ELSD, CAD, CLND, FID, VUV, MS, NMR, and hyphenated detection, with the focuses on the "universal" features of these detectors regarding the types of molecules they can detect and the uniformity of responses. [ABSTRACT FROM AUTHOR]

Abstract This paper reports the details of a numerical study undertaken to evaluate seismic response factors for steel buckling-restrained braced frames (BRBFs) using the FEMA P695 methodology. In the United States, BRBFs are designed according to Minimum Design Loads for Buildings and Other Structures (ASCE 7) and the Seismic Provisions for Structural Steel Buildings (AISC 341). Twenty-four archetypes were designed according to the U.S. specifications and their behavior was assessed by making use of non-simulated collapse models. The interstory drift, brace axial strain and cumulative brace axial strain demands under collapse level ground motions were determined. The results obtained indicate that the current seismic response factors are adequate in terms of interstory drift and cumulative axial strain demands. On the other hand, large differences between the design level and collapse level axial strains were reported, which can result in undesirable brace behavior. Modified approaches were developed to estimate the axial strains for collapse level ground motions. These include a modification to the deflection amplification factor and a modification to the AISC 341 requirements for expected brace deformations. The archetypes were redesigned using the proposed modifications and reevaluated using the FEMA P695 methodology. The results indicate that the proposed modifications result in axial strain demands that are in close agreement with the calculated demands. Highlights • Seismic response factors used for BRBFs were evaluated using FEMA P695 Methodology • Twenty-four archetypes were designed and analyzed under collapse level ground motions • Brace axial strains were found to be significantly higher than the demands calculated at the design stage • Deflection amplification factors that vary over the height were proposed • A modification to AISC 341 was proposed for amplification of brace strain demands [ABSTRACT FROM AUTHOR]

Sulfated polysaccharides (SPS) have attracted a lot of interest because of their diverse pharmacological functions. Numerous scientific studies have shown that SPS exhibit better biological activity than those that are not sulfated, such as immunomodulatory, anti-viral, and antioxidant activities. A crucial step to a better understanding of the mechanism of action and health effects is the production of high purity SPS. This calls for the development of selective assay techniques that can identify SPS preferentially without being influenced by other substances or the co-extracted polysaccharides. A universal modified toluidine blue (TB) assay was developed in this study to detect SPS. The assay procedures were conducted using different SPS standards including fucoidans from different biogenic sources, in addition to heparin and dextran sulfate. Spectroscopic response factor was calculated for each SPS which showed very good correlation (R2 = 0.998) with the corresponding sulfation degree. The proposed method was applied for determination of SPS content of crude fucoidan product using five different SPS standards. The method was cross validated by conducting ANOVA test to the obtained % recovery revealing that there is no significant difference between the results obtained by identical reference standard and four nonidentical natural SPS standards. This is the first report of a selective universal assay of SPS that enables the selective determination of SPS using a nonidentical reference standard. [Display omitted] • A novel sulfation degree corrected response factor-based TB assay was developed. • Sulfated polysaccharides with various sulfation degree were used for response factor calculation. • The calculated response factors showed a good correlation to the corresponding sulfation degree. • Absorbance normalization enabled response factor calculation. • Fucoidan content was determined using non-identical reference material. [ABSTRACT FROM AUTHOR]

The heat and mass transfer simulation model of a ground heat exchanger (GHE) directly affects the design and operation performance of a ground-coupled heat pump system. The GHE models based on the response function (like the Green function and g-function) can achieve a fast calculation speed. However, the heat sources in these models are limited to points or whole boreholes, leading to low calculation accuracy in heat transfer during a short time period and limitation to a certain GHE. A general distributed parameter model for a ground heat exchanger (RF model) is proposed based on the principle of response factors in this paper. A sandbox experimental platform is then built to test the temperatures of typical points in the double-layered soil and to validate the RF model. After that, the calculation of the RF model is simplified by determining suitable positions for the soil boundaries and the numbers of sub pipes and sub soil boundaries. Finally, the RF model is applied in different scenarios to demonstrate its characteristics. The results show that: (1) the RF model is suitable for different kinds of GHEs with arbitrary shape and type of heat sources releasing heat in arbitrary time steps; (2) the RF model has only 0.01 °C and 0.23 °C temperature response errors compared to those from numerical solutions and experiments, respectively; (3) the general RF model has similar accuracy to the numerical solution in calculating the distributed temperatures of the borehole and pipes, heat transfer in the short term, and heat transfer of borehole groups and the energy pile. [ABSTRACT FROM AUTHOR]

Since linear calibration is mostly preferred for analytical determinations, linearity in the calibration range is an important performance characteristic of any instrumental analytical method. Linearity can be proved by applying several graphical and numerical approaches. The principal graphical criteria are visual inspection of the calibration plot, the residuals plot, and the response factors plot, also called sensitivity or linearity plot. All of them must include confidence limits in order to visualize linearity deviations. In this work, the graphical representation of percent relative errors of back-calculated concentrations against the concentration of the calibration standards is proposed as linearity criterion. This graph considers a confidence interval based on the expected recovery related to the concentration level according to AOAC approach. To illustrate it, four calibration examples covering different analytical techniques and calibration situations have been studied. The proposed %RE graph was useful in all examples, helping to highlight problems related to non-linear behavior such as points with high leverage and deviations from linearity at the extremes of the calibration range. By this way, a numerical decision limit which takes into account the concentration of calibration standards can be easily included as linearity criterion in the form of %RE Th =2·C −0.11 . Accordingly, this %RE parameter is accurate for the decision-making related to linearity assessment according to the fitness-for-purpose approach. [ABSTRACT FROM AUTHOR]

• An innovative analytical method was developed combining UV and MS detection. • Response factors in MS for each oleuropein metabolite were calculated. • For the first time, conjugated derivatives of oleuropein aglycone were quantified. • This method could be applied to other phenolics with lack of commercial standards. The beneficial health effects of phytochemicals depend on their bioavailability and the form under which they reach systemic circulation, usually as phase II metabolites. The lack of authentic standards for these metabolites makes their quantification in biological samples challenging. A new analytical approach to get a more accurate quantification of oleuropein metabolites in biological samples after ingestion of olive leaf extract was proposed. This approach was based on the calculation of a response factor in QTOF MS for each metabolite, comparing their quantification in UV and MS using urine samples concentrated in the metabolites of interest. Glucuronide and sulfate conjugates of hydroxytyrosol and homovanillyl alcohol were more accurately quantified in plasma and urine and for the first time, oleuropein aglycone conjugates and their hydroxylated and hydrogenated derivatives were quantified after consumption of olive products. This approach could be extensible to the analysis of other phenolic metabolites when authentic standards are not available, opening a valuable method for bioavailability studies. [ABSTRACT FROM AUTHOR]

In this investigation, off-line comprehensive two-dimensional liquid chromatography–atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π–π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography–mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography–mass spectrometry data were analyzed using principal component analysis. The results of the principal component analysis enabled a clear identification of different plant oils. By using this two-dimensional liquid chromatography–mass spectrometry system coupled with principal component analysis, adulterated soybean oils with 5% added lord oil and peanut oils with 5% added soybean oil can be clearly identified. [ABSTRACT FROM AUTHOR]

Highlights: [•] A list of odorants released from waste-related strong sources pose significant nuisance problems. [•] An experimental method to concurrently measure various odorants is developed for actual application. [•] The reliability of this method is tested and validated against a number of strong source environments. [ABSTRACT FROM AUTHOR]

The use of mass spectrometry methods with triple quadrupole instruments is well established for quantification. However, the preparation of calibration curves can be time-consuming and prone to analytical errors. In this study, an innovative internal calibration (IC) approach using a one-standard calibration with a stable isotope-labeled (SIL) standard version of the endogenous compound was developed. To ensure optimal quantitative performance, the following parameters were evaluated: the stability of the analyte-to-SIL response factor (RF), the chemical and isotopic purities of the SIL, and the instrumental reproducibility. Using six clinically important endogenous steroids and their respective SIL standards, we demonstrated that RFs obtained on different LC-MS platforms were consistent. The quantitative performance of the proposed approach was determined using quality control samples prepared in depleted serum, and showed both satisfactory precision (1.3%–12.4%) and trueness (77.5%–107.0%, with only 3 values outside ±30%). The developed method was then applied to human serum samples, and the results were similar to those obtained with the conventional quantification approach based on external calibration: the Passing-Bablok regression showed a proportional bias of 6.8% and a mean difference of −5.9% between the two methodologies. Finally, we showed that the naturally occurring isotopes of the SIL can be used to provide additional calibration points and increase the accuracy for analytes with low concentrations. [Display omitted] • An internal calibration was developed for six endogenous steroids quantification in serum. • Fast quantification was achieved with one-standard calibration using SIL. • Trueness and precision were verified prior to application in real samples. • Accuracy for low concentrated analytes was enhanced by monitoring SIL isotopes. [ABSTRACT FROM AUTHOR]

Currently, the presence of many classes of volatile organic compounds (VOCs) in indoor air is well recognized. There is an impetus to accurately quantify airborne VOCs for the proper assessment of their human health risks. VOC standards prepared in a solvent are often vaporized in N 2 gas-filled sampling bags for external calibration as the use of grab sampling bags is a common practice for the collection of real ambient air samples. Such practices can nontheless be subject to many sources of biases in their calibration (e.g., VOC chemical reaction with the solvent, adsorption on the bag interior surface, or leakage). The main goal of this work is to measure the temporal stability of 11 VOC targets (benzene, toluene, o-xylene, styrene, propionaldehyde, n-butyraldehyde, isovaleraldehyde, valeraldehyde, acrylonitrile, isoprene, and methyl ethyl ketone) selected in this research over 24 h which started 10 min after the injection and vaporization of liquid-phase standards (all prepared in methanol solvent) into polyester aluminum (PEA) bags containing 1 atm N 2. Although all tested VOCs showed gradual decreases of their concentrations (e.g., >17% in 24 h), the aromatic hydrocarbon VOCs (namely BTXS) yielded the best relative recoveries (e.g., decreases of 11%–30% in 24 h) and relative errors (e.g., relative standard error (RSE) = 2.14–3.59%) in 5 replicate tests. A good linear relationship was established between the 24 h VOC relative recovery and molecular weight (R2 > 0.81). The results of this study offers valuable clues to properly reduce the bias in the calibration of gas-phase VOC standards when calibrating the system through the vaporization of liquid-phase VOC standards prepared in a solvent. [Display omitted] • A total of 11 VOCs were injected to and stored in polyester aluminum (PEA) bags. • Short-term changes in VOC concentrations in PEA bags were measured. • Their relative recovery was calculated at each time interval up to 24 h. • Aromatic VOCs showed enhanced stability relative to other types of VOCs. • Relative recovery of VOCs was predictable in relation to their molecular weight. [ABSTRACT FROM AUTHOR]

Abstract: The application of gas mass-flow meters (GMFM) sensors needs the knowledge of its measurement model and measurement uncertainties. It was already known that the GMFM output model depends on gas mass-flow and gas composition. In this work, different throughput GMFM sensors were used for different gas flow rates and gas composition in order to verify and to improve the GMFM measurement model. A direct calibration procedure and a dynamic volumetric method were applied both to get the measurement model and to evaluate the performance of gas sensors and GMFM sensors against certified reference materials and suitable standards. Additionally, the obtained data were used both to calculate the uncertainties of gas mass-flow measurement and to improve the GMFM gas response factors. The calculated uncertainties of the GMFM direct measurement was approximately 2% of the measured value. The uncertainty of the dynamic volumetric method developed in this work was found as approximately 5% of the measured value and that was mainly influenced by the uncertainties of the standards used. [Copyright &y& Elsevier]

Abstract: In case airborne pollutants have been accidentally released indoors, knowing release locations and rate profiles of the pollutant sources is always beneficial. Current inverse models can locate a pollutant source but have difficulty quantifying its temporal release rate. This study proposes an inverse method based on Tikhonov regularization and least-squares optimization using computational fluid dynamics (CFD) to quantify the temporal release rate of a gaseous pollutant source. The Tikhonov regularization adds a regularized term to the objective function of the concentration and imposes a bound on the solution. The release rate can then be solved based on the inverse matrix operation with the monitored concentration series at a particular location. To accelerate the solving procedure, the gas concentration is expressed as the convolution integral between the concentration response of a unit impulse release (response factor) and the arbitrary release profile. This study finds that the developed inverse method can accurately and efficiently quantify the intermittent gas release in both constant and sinusoidal forms. The only prerequisites to implement the proposed inverse method are a steady flow field, a known fixed source location and the monitored temporal concentration at a point in space. [Copyright &y& Elsevier]

Abstract: The Dynamic Thermal Network (DTN) approach to the modelling of transient conduction was conceived by Claesson (1999,2002,2003) as an extension of the network representation of steady-state conduction processes. The method is well suited to the simulation of building fabric components such as framed walls and thermally massive structures such as basements but can also be applied to the long timescale simulation of other conduction problems. The theoretical basis of the method and its discretized form is outlined in this paper and a new numerical procedure for the calculation of the necessary weighting factor data is presented. Such data has previously been generated for three-dimensional bodies by a heuristic process of blending analytical solutions and numerical data. The numerical approach reported here has the advantage of accommodating parametric representations of multi-dimensional geometries and allows the data to be produced in an automated fashion and so more easily incorporated into simulation tools. Enhancements to the data reduction procedure and a generalised approach to representing complex boundary conditions are also presented. The numerical procedure has been validated by a series of comparisons with analytical conduction heat transfer solutions and discretization errors were found to be acceptably small. Compared to numerical methods, calculations using the DTN method were found to be up to four orders of magnitude quicker but with comparable accuracy. [Copyright &y& Elsevier]

Abstract: An alternative methodology for simultaneous analysis of majority cis–trans fatty acids such as stearic (C18:0), elaidic (C18:1t), oleic (C18:1c), palmitic (C16:0), linoleic (C18:2cc) and linolenic (C18:3ccc) by capillary zone electrophoresis (CZE) under indirect detection was proposed in this work. The CZE methodology was optimized through the 23 central composite design (23 CCD) with three replicates in central point, having as factors Brij 35, acetonitrile and 1-octanol. The background electrolyte (BGE) for the optimum separation condition consisted of: 15.0mmolL−1 of NaH2PO4/Na2HPO4 buffer at pH≈6.86, 4.0mmolL−1 of SDBS, 8.3mmolL−1 of Brij 35 and 45% v/v of ACN, and 2.1% of 1-octanol was achieved by analyzing of the 23 CCD together with the principal component analysis (PCA). The FA quantification was performed through response factor (Rf) approach, which provided high analytical throughput for the real samples analysis. The CZE method optimized was successfully applied to the analysis of FA in samples of olive oil, soy oil, hydrogenated vegetable fat, butter, margarine and filled cookie. The results obtained were compared with AOCS GC official method (Ce 1j-07) through paired sample t test and no significant difference was found within 95% confidence interval. [Copyright &y& Elsevier]

Abstract: The non-reciprocity of magneto-optical reflection response by surface plasmon excitation in a planar glass/Fe/Au/air system with prism coupling is studied. We aim to find the optimal thicknesses of metallic layers with regard to the reflectance sensitivity to an external magnetic field. For this purpose, a corresponding response factor is introduced and applied. The numerically modeled prediction of sensitivity is verified by experimental measurements. [Copyright &y& Elsevier]

Abstract: A protocol for the analysis of multiple prostaglandins and leukotrienes in cell culture media by using multiple internal standards was validated. A two-factor Doehlert design was used to determine the behaviour of the relationship analyte/internal standard (namely: PGE2/PGE2-d 4, PGE3/PGE2-d 4, LTB4/LTB4-d 4 and LTB5/LTB4-d 4) and to select the optimal amounts of deuterated internal standards for quantifying simultaneously the prostaglandins and leukotrienes in cell culture media by LC–MS/MS. The selection of optimal amounts of internal standards was based on mathematical models that allow visualizing concentration regions where the response factors remain constant over a wide range of analytical concentrations. The linearity of the calibration curves for each analyte at the optimal levels suggested by the mathematical models was statistically confirmed by means of the ratio lack-of-fit to pure error. The validated protocol was successfully applied in the simultaneous quantification of pro- and anti-inflammatory eicosanoids in stimulated cod head kidney cell culture media. The two-factor Doehlert design has permitted to estimate the experimental response as a function of six variables (PGE2, PGE3, LTB4, LTB5, PGE2-d 4 and LTB4-d 4) which represents a substantial reduction of resources, time and experiments of approximately 84% (7×3 experiments) when compared with the full six-factor Doehlert design (43×3 experiments). [Copyright &y& Elsevier]

Abstract: Reduced sulfur compounds (RSCs) were measured at low concentrations in small volume air samples using a cryo-trapping inlet system and gas chromatograph outfitted with a sulfur chemiluminescence detector (GC-SCD). The relative sensitivity of the system to the RSCs follows the sequence H2S6 years from initial coating) saw significant loss of H2S and CH3SH within 2 days, while the more recent generation canister (<1 year from initial coating) yielded percent recoveries of RSCs in the range of 85% (H2S and CH3SH) to 95% (OCS, DMS and CS2) after 7 days of storage, suggesting that these canisters may be suitable for the short-term storage of low level RSCs. The development of this low concentration, low sample volume method is well suited for measuring RSC gas fluxes from natural soils in laboratory incubations and in field flux chamber studies. [Copyright &y& Elsevier]

Abstract: Volatile organic compounds (VOCs) play an important role in the chemistry of the atmosphere and in biogeochemistry. They contribute to the oxidative capacity of the atmosphere, particle and air pollutants, as well as to the production of greenhouse gasses (for instance ozone). Among analytical techniques for their determination in the atmosphere gas chromatography coupled with mass spectrometry (GC–MS) offers several advantages. However, for an accurate quantification calibration with standard substances is necessary. A quantitative structure–property relationship (QSPR) model for the prediction of MS response factors was developed on basis of our experimental measurements for the quantification of ozone precursors present in the atmosphere. A linear correlation between chemical structures and response factors was established by using a 7-parameter MLR model. The average error in the prediction of response factors was calculated by cross-validation procedure and was below 20%, which is sufficient for the determination of VOCs in the air. The proposed procedure is time consuming so it is more suited for the quantification of tentatively identified organic compounds during the reprocessing of MS chromatograms in cases when the original sample is no longer available. [Copyright &y& Elsevier]

Abstract: The universality of the response of the Corona Charged Aerosol Detector (CoronaCAD) has been investigated under flow-injection and gradient HPLC elution conditions. A three-dimensional model was developed which relates the CoronaCAD response to analyte concentration and the mobile phase composition used. The model was developed using the response of four probe analytes which displayed non-volatile behavior in the CoronaCAD and were soluble over a broad range of mobile phase compositions. The analyte concentrations ranged from 1μg/mL to 1mg/mL, and injection volumes corresponded to on-column amounts of 25ng to 25μg. Mobile phases used in the model were composed of 0–80% acetonitrile, mixed with complementary proportions of aqueous formic acid (0.1%, pH 2.6). An analyte set of 23 compounds possessing a wide range of physicochemical properties was selected for the purpose of evaluating the model. The predicted response was compared to the actual analyte response displayed by the detector and the efficacy of the model under flow-injection and gradient HPLC elution conditions was determined. The average error of the four analytes used to develop the model was 9.2% (n =176), while the errors under flow-injection and gradient HPLC elution conditions for the evaluation set of analytes were found to be 12.5% and 12.8%, respectively. Some analytes were excluded from the evaluation set due to considerations of volatility (boiling point <400°C), charge and excessive retention on the column leading to elution outside the eluent range covered by the model. The two-part response model can be used to describe the relationship between response and analyte concentration and also to offer a correction for the non-linear detector response obtained with gradient HPLC for analytes which conform to the model, to provide insight into the factors affecting the CoronaCAD response for different analytes, and also as a means for accurately determining the concentration of unknown compounds when individual standards are not available for calibration. [Copyright &y& Elsevier]

Abstract: Gas mass-flow meters (GMFM) for original equipment manufacturers (OEM) applications are presently found in a relatively easy and cheap way. GMFM may be applied in a number of different situations but technical information concerning its principles of measurement and applications is still misleading. In this paper, the principles of GMFM measurement are discussed and the operating parameters are clarified. A concept of gas mass-flow response factor is introduced and further used in a model for gas mass-flow measurement that is suitable to any gas mixture of known composition. In addition, a model for the application of GMFM to dynamic volumetric methods of dilution is presented and generalized. [Copyright &y& Elsevier]

Abstract: The characterization and quantification of extra-virgin olive oil (EVOO) phenolic compounds by a rapid resolution liquid chromatography (RRLC) method coupled to diode-array and time of flight mass spectrometry (TOF) detection systems was developed. The RRLC method transferred from a conventional HPLC one achieved better performance with shorter analysis times. The phenolic compounds were separated with a C18 column (150 mm×4.6mm, 1.8μm) using water with 0.5% acetic acid and acetonitrile as mobile phases. Good peak resolution was obtained and 19 different phenols were identified in less than 20min providing a new level of information about the samples in shorter time. The applicability of this analytical approach was confirmed by the successful analysis of three different EVOO varieties (Picual, Hojiblanca, and Arbequina) obtained from different trademarks. Besides identification of the most important phenolic compounds and their quantification in three different ways (RRLC-UV, RRLC-MS and a new approach using the total polyphenol content obtained with Folin Ciocalteau, the relative areas and the response factors), we also described the occurrence of correlations between the phenolic composition of EVOO-derived crude phenolic extracts and their anti-proliferative abilities toward human breast cancer-derived cell lines. When compared with lignans-rich EVOO varieties, secoiridoids-rich EVOO had a significantly strong ability to alter cell viability in four different types of human breast carcinoma cells. [Copyright &y& Elsevier]

Abstract: It was hypothesized that the hydrophilic interaction liquid interface chromatography (HILIC) mode should produce more response than the reversed-phase HPLC mode on detectors with an evaporative component to the detection process. HILIC mobile phases are mostly composed of polar organic solvent and are more volatile than reversed-phase mobile phases. Therefore the more easily evaporated HILIC mobile phases should produce greater sensitivity for those detectors that remove mobile phase by evaporation. The responses of 12 compounds were measured in the reversed-phase mode and the HILIC mode with three detectors: evaporative light scattering detector (ELSD), corona charged aerosol detector (cCAD), and electrospray mass spectrometry (ESI-MS). The compounds studied were very polar compounds that were retained in the HILIC mode. Generally, the HILIC mode was able to achieve greater sensitivity than the reversed-phase mode for these compounds. The increases in sensitivity observed can be attributed to the more volatile HILIC mobile phase. For the ELSD, the HILIC mode produced slightly greater sensitivity than the reversed-phase mode. The cCAD was approximately 10 times more sensitive in the HILIC mode and the ESI-MS was approximately 5–10 times more sensitive in the HILIC mode. There was one instance in the study where a compound produced more response in the reversed-phase mode. Thymine yielded more sensitivity in the reversed-phase mode with the ESI-MS detector. In a given mode of operation, there was significant variation in the measured response factors for all compounds on each detector. While this is not unexpected for the ESI-MS detector, variation in the response factors between compounds indicates that the cCAD and ELSD are not truly universal detectors in the sense that all compounds have identical responses. [Copyright &y& Elsevier]

Abstract: Intrinsic sorption rates of ligand/receptor binding have been measured by surface plasmon resonance (SPR) using response factors for deposition of proteins or smaller molecules on planar surfaces. In this study, generalized expressions for SPR response factor and effective refractive index are developed to measure rates of analyte sorption onto 3-D surfaces. The expressions are specialized for two limiting cases of immediate practical interest and broad applicability: analyte deposition onto a homogeneous anisotropic porous media and deposition onto close-packed solid spheres adjacent to the sensor surface. These new equations specify media capacity, characteristic size and analyte concentration that are necessary to obtain identifiable responses from interaction with anisotropic porous media or chromatographic resin. These developments are illustrated by comparing response factors for Adenovirus type 5 on planar surfaces, porous media and adsorptive spheres. [Copyright &y& Elsevier]

The current paper presents a logical extension of previous work [Lukić N. The transient house heating condition—the building envelope response factor (BER). Renewable Energy 2003;28:523–32.]. The daily changes of the earlier introduced building envelope response factor (BER) are shown, under transient heating conditions, during the first three heating days after a long non-heating period. Four simulation cases were studied: two-layered thermal-insulation-concrete house walls where the thermal-insulation had in, out and middle position according to inside of house and one-layered concrete house walls. Three different behaviors of central radiator heating system were simulated. The BER factor is considered an important pointer on influence of house walls to heating/cooling energy consumption and thermal comfort during transient conditions. In numerous simulations, using BER factor presentation, the start heating-period was investigated up to the achievement of defined thermal comfort inside the building walls. Alongside of the expected start peak, local peaks and off-peaks of BER factor appeared during first three heating days. Recognition of the daily changes of BER factor could enable aims, lower energy consumption and a rapid achievement of good thermal comfort. In this attempt, a building envelope, as a passive source of energy, is a critical factor. [Copyright &y& Elsevier]

Lysophosphatidic acid (LPA; 1-acyl-2-hydroxy-sn-glycero-3-phosphate) is a lipid growth factor that stimulates the proliferation of ovarian cancer cells. Recent studies indicate that elevation of cellular cAMP levels inhibits ovarian epithelial cancer cell growth. In this study, we investigated the effects of elevating cellular cAMP levels on LPA stimulation of OVCAR-3 ovarian cancer cell growth and on LPA stimulation of the serum response factor (SRF) transcription factor. Treatment of OVCAR-3 cells with forskolin and isobutylmethylxanthine (IBMX; 3-Isobutyl-1-methylxanthine) inhibited LPA stimulation of growth. LPA stimulation of SRF-mediated transcription was also inhibited in OVCAR-3 cells that were incubated with forskolin, dibutyryl cyclic AMP (db-cAMP), or paired cAMP analogues (N6-mono-tert-butylcarbamoyladenosine-3′, 5′-cyclic monophosphate [6-MBC-cAMP] and Sp-5,6-DCl-BIMPS), which selectively activate type II protein kinase A. In contrast, incubation with a cAMP analogue (8-(4-chloro-phenylthio)-2′-O-methyadenosine-3′,5′-cyclic monophosphate [8CPT-2Me-cAMP]) that specifically activates the cAMP inducible Rap1 exchange factor, Epac, did not inhibit SRF. Similar results were obtained when HepG2 hepatoma cells, which do not express endogenous LPA receptors, were transfected with a single LPA receptor (LPA1). We observed that treatment of OVCAR-3 cells with forskolin greatly reduced both F-actin staining and focal adhesion labeling with anti-paxillin antibodies. Treatment of OVCAR-3 cells with the F-actin stabilizing compound, jasplakinolide, prevented the protein kinase A (PKA)-mediated inhibition of SRF. These results suggest that PKA inhibits LPA stimulation of SRF by promoting the dissolution of F-actin and that this is likely to contribute to the cAMP-mediated inhibition of ovarian cancer cell growth. [Copyright &y& Elsevier]

In this paper influence of house walls on heating energy consumption and indoor thermal comfort was investigated. The simulations were carried out using an extended dynamical model of building-software ZID under transient conditions, like the first heating day after a long non-heating period. Four simulation cases were considered: two-layered thermal-insulation concrete house walls were used, where the thermal insulation was inserted in the inner, outer or middle positions according to the inside of the house, and one-layered concrete house walls. The influence of the house walls on internal thermal comfort and heating process is presented by two introduced factors: thermal comfort degree-hour and building envelope response factor (BER factor). This new BER factor could be a significant variable in considering house walls as a passive heating energy source. The conclusion is that under certain conditions the BER factor is at a maximum, at which point the influence of house walls on inside thermal comfort and heating energy consumption is also at a maximum. [Copyright &y& Elsevier]

[Display omitted] • The problems of two common borehole design methods are pointed out. • The dynamic characteristic diagrams of borehole heat transfer are summarized. • The new diagram method only has design error about −5% to 10%. • The modification avoids the design error of 48 h TPT method about 13%–20%. • The heating reliability is improved and energy efficiency is increased. For ground source heat pumps with boreholes, the rule-of-thumb and thermal performance test (TPT) methods are commonly adopted for borehole design but suffer from inaccuracy. The response factor model can calculate the time-varying soil heat transfer of boreholes fast and accurately. Based on the response factor model, the characteristic diagrams of borehole heat transfer are summarized to show the influential laws of different factors (borehole inlet temperature, velocity of fluid inside the pipe, initial soil temperature, soil thermophysical properties, and operation time). The characteristic diagrams can be used as a new design method that improves the accuracy of the rule-of-thumb method by considering different influential factors and avoiding the subjective errors of designers. For different soils, the borehole design errors of the new diagram method are −5% to 10%, which are much less than the errors (−15% to 72%) of the conventional rule-of-thumb method. In addition, a modification to the TPT method is also proposed using the response factor model. The borehole design errors of the conventional TPT method (48 h testing) can be reduced by 13%–20% using the derived correction factors. The proposed modification methods contribute to more reasonable borehole design, improved heating reliability as well as increased energy efficiency. [ABSTRACT FROM AUTHOR]

• HLIC CAD analysis of alcohol ethoxylated surfactants. • Isolation of homologues by semipreparative separation. • Determination of response factor of homologues. • Unexpected very different response factors. Surfactants are used in various applications: cosmetics, pharmaceuticals, petrochemicals, environmental, etc. Many of these compounds are polydisperse, and because of this intrinsic polydispersity, it is essential to have a universal detector with a uniform response to quantify them in a simple way. Indeed, Charged Aerosol Detector (CAD) was presented as a universal detector with a uniform response. Thus, in the present study, the CAD response, in a High-Performance Liquid Chromatography - CAD configuration (HPLC CAD), was evaluated using purified alcohol ethoxylated surfactants. A semi-preparative liquid chromatography step using a Hydrophilic interaction chromatography (HILIC) bare silica column (150 mm, 4.6 mm, 2.6 µm) was implemented to prepare eleven homologues of BrijC10, a nonionic surfactant. These homologues differed only by the number of ethylene oxide units. BrijC10 homologues were analyzed by HPLC CAD, using a HILIC bare silica column (150 mm, 2.1 mm, 2.6 µm) to determine the HPLC CAD response factors of purified homologues. From the calibration curves (from 100 to 500 mg.kg−1), their response factors were estimated: differences in response factors were observed and a maximum difference in response factors of 3.6 was obtained. Thus, it could be concluded that CAD hyphenated to HILIC separation did not present a uniform response for this homologue's distribution. [ABSTRACT FROM AUTHOR]

• Dynamic thermal properties of Double skin façade significantly influence on heat flow. • The theoretical approximation can lead to substantial gap with the real properties. • The response factor can be a useful index to estimate the thermal performance of DSFs. • The energy simulation with the response factor can reduce the substantial gap. Modern office buildings frequently adopted Double-skin façades (DSFs) to save energy use for heating and cooling. The operable layers of a DSFs are designed to control the heat and airflow in its flow domain. The dynamic thermal properties of the operable layers should be well understood for the successful design of a DSFs. The objective of this study was to provide easy and reliable calculation method for cooling or heating load of a DSFs under dynamic weather conditions. The heat transfer in the operable layers was expressed by using the response factor which was got from field monitored data as a transfer function of incident solar radiation and exterior surface temperature at the inner glass of a DSFs. The proposed model was validated by the energy simulations with TRNSYS and field monitoring conducted during 35 days in summer, 6 August to 9 September 2012. From the results, it was found that the response factor is a very useful index to predict the thermal performance of a DSFs. The exterior surface temperature of the DSFs predicted by the response factor was fitted well with the field monitored data in both blind rolling and rolling off conditions. The mean bias error (MBE) and root mean square error (RMSE) of the predicted temperature were within 1.5% and 2.1%, respectively. The models can be helpful to evaluate the thermal performance of DSFs at the early building design stage. [ABSTRACT FROM AUTHOR]