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A field experiment was conducted at the University of Baghdad, Al-Jadriya in the spring season of 2021 for the potato crop under the influence of organic biofertilizers and water stress. Three levels of bio-organic fertilizers were used 0 (OM0), 1 (OM1) and 1.5 (OM2) ton ha-1 and three levels of irrigation 30 (I-30), 50 (I-50) and 75 (I-75) % water depletion were available to evaluate the role of bio-organic fertilizer and water stress in production functions and water use efficiency. I-30 treatment showed the highest water consumption ranging between 468 and 486 mm season-1 and decreased to 355-436 mm with water stress treatments I-75. The values of water consumption varied according to the levels of bio-organic fertilizer. The percentage of decrease in water consumption was 1.49 and 3.66% at low stress and reached 6.37% at high stress (I-75) compared to OM0. Both treatments I-30 and I-50 gave the same yield. Bio-organic fertilization led to an increase in the average yield of tubers 32.8 and 41.9% for both OM1 and OM2 compared to OM0. The production functions indicate that the yield increases by 0.057 ton ha-1 mm-1 of added water, and the water depth must be greater than 64.2 mm to obtain a yield that is 1.96 ton ha-1 more (significant limit) than the treatments in the experiment (1.96=0.057(Irr.). )-1.70). Fertilizer levels are higher than 1.9 ton ha-1 to obtain a higher yield of tubers by 26.29 tons/ha and the efficiency of water use is nil according to the water use function when the water consumption is higher than 692.7 mm. The response factor decreased when adding bio-organic fertilizer compared to OM0, which means that plants were not affected significantly under water stress conditions.

Objective The aim is to solve the analysis problems on the accurate determination of micro-trace impurity components in the high-quality development of China’s hydrogen energy industry. Methods For the quality analysis of hydrogen fuel, a gas dilution method based on the principle of critical flow orifices was established. As the major component of the sample to be tested is hydrogen rather than nitrogen, the math module of flow response factor is studied to investigate the influences on the flow of different gases. Results The dilution ratio of this method could achieve over 1∶1 000 with a relative expand uncertainty of better than 1%. The gas reference materials, namely formaldehyde and methane in hydrogen, are prepared in a 10-9 molar fraction level dynamically. The measured repeatability of concentrations of the gas reference materials is no more than 7%. The linear correlation coefficient R~2 of each diluted concentration is more than 0.999. Conclusions The analysis results of formaldehyde in nitrogen and in hydrogen respectively conclude that the math module of flow response factor is reliable, and the accuracy of this gas dilution method will be improved after a correction by flow response factor. [ABSTRACT FROM AUTHOR]

A modified elution condition for organic acids in meat chromatographed by aged sulfonated polystyrene-divinylbenzene (SPD) column was compared to common elution conditions in terms of efficiency, selectivity, resolution, peak shape, precision, and accuracy. The mobile phase concentration (mM), flow rate (mL/min), and column temperature (℃) under common elution conditions (CECs) changed from 10 to 25, 0.6 to 0.2, and 60 to 40 in modified elution (MEC), respectively. A total of 15 peaks were detected in both elution conditions. Seven of them were confirmed with the available authentic organic acid standards including citric, pyruvic, succinic, lactic, acetic, propionic, and butyric acid. A good efficiency, selectivity, resolution, and peak shape were obtained for organic acids chromatographed on aged SPD column with MEC compared to CEC. The analyte was quantified using external standard technique. High response factor, expected correction factor, better calibration sensitivity and repeatability, and also accuracy for organic acids were observed under MEC. In particular, when peak broadening was observed in the aged SPD column, good chromatographic separation could be obtained with MEC in terms of resolution and peak shape was associated with better precision and recovery for organic acids in meat. [ABSTRACT FROM AUTHOR]

We performed quantum chemical calculations based on the density functional theory (DFT) for the all-E- and several Z-isomers of three commercially important carotenoids (lycopene, β-carotene, and astaxanthin) and theoretically obtained the UV-Vis spectrum, response factor (determined from absorption intensities of the all-E- and the Z-isomers), and Q-ratio for each carotenoid isomer. The calculated spectra reproduced the experimental spectral shapes (e.g., the appearance of the Z-peaks and the blue shift of the main peaks for the Z-isomers) very well. The calculated response factors and Q-ratios also showed good agreement with reported values. Notably, response factors, which are difficult to determine experimentally, were well reproduced. These results suggest that quantum chemical calculations can be an effective tool for refining quantitative analysis and obtaining spectral data for carotenoids for which standards are difficult to obtain., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Masaki Honda reports financial support was provided by Japan Science and Technology Agency., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The quality control of medicinal cannabis should include quantification of as many cannabinoids as practicable in a routine analytical lab, to accurately reflect the quality of the product. However, the cost and availability of some cannabinoid standards is an impediment to their routine use. This work seeks to overcome this obstacle by analysing samples using relative retention times (RRT) and relative response factors (RRF), relative to CBD and CBDA reference standards which are readily available. A high-performance liquid chromatography-photodiode array method was developed to quantify ten cannabinoids (Δ9-THC, Δ8-THC, THCA-A, CBN, CBD, CDBA, CBC, CBDV, CBG, and CBGA) in dried cannabis inflorescence and cannabis oil. This method was validated according to ICH guidelines. The proposed method has detection limits ranging from 20 to 78 µg/g, which provided sufficient sensitivity for the panel of cannabinoids. Non-cannabinoid surrogate matrices were used for spike recovery studies to determine method accuracy – analyte recoveries for the inflorescence and oil ranged from 90.1 to 109.3% (inflorescence mean, 100.9%; oil mean, 99.6%). The RRT and RRF values determined independently by three analysts were comparable, indicating the method is robust. The validity of analysis using RRT and RRF was further confirmed by testing six inflorescence samples, as it was found that concentrations above the order of magnitude of the LoQ agreed satisfactorily (range, 95.0 to 111.9%; mean, 100.0%) with the concentrations obtained through the conventional approach of multipoint calibration using pure standards. The proposed method is therefore suitable for the rapid and simple determination of a panel of ten cannabinoids without having to repeatedly purchase every expensive pure standard. Accordingly, analysts in the medicinal cannabis field may explore the use of RRF and RRT for their methods and instruments.

Estuarine environmental capacity is the foundation for coastal biological diversity and self-purification capacity. Hence, studies on the marine environmental capacity (MEC) are the foundation for the total discharge control and water quality improvement of land-based pollutants. In the article, A calibrated two-dimensional hydrodynamic model was used to study the environmental characteristics of Sanmen Bay, including the tides, the residual currents, the tidal prism, and water exchange abilities. The model results were used to estimate the environmental capacity of the bay. Taking the pollution problem in Sanmen Bay as an example, the method of response factor, the sub-unit control method, and the phased control method were used to estimate the environmental capacity, pollutant amounts, and the pollutant reduction in the bay. The concentrations of COD, inorganic nitrogen, and acid salt in Sanmen Bay are spatially varied, with higher values occurring in the western part and in the inner bay. The half exchange time of the whole bay is about 23 days, and the exchange time of 95% water body is about 60 days. The evaluation of MEC cannot only provide technical support for the offshore aquaculture industries but also provide a scientific basis for the total control of terrigenous pollutants in coastal cities in Southern Zhejiang Province. [ABSTRACT FROM AUTHOR]

Estuarine environmental capacity is the foundation for coastal biological diversity and self-purification capacity. Hence, studies on the marine environmental capacity (MEC) are the foundation for the total discharge control and water quality improvement of land-based pollutants. In the article, A calibrated two-dimensional hydrodynamic model was used to study the environmental characteristics of Sanmen Bay, including the tides, the residual currents, the tidal prism, and water exchange abilities. The model results were used to estimate the environmental capacity of the bay. Taking the pollution problem in Sanmen Bay as an example, the method of response factor, the sub-unit control method, and the phased control method were used to estimate the environmental capacity, pollutant amounts, and the pollutant reduction in the bay. The concentrations of COD, inorganic nitrogen, and acid salt in Sanmen Bay are spatially varied, with higher values occurring in the western part and in the inner bay. The half exchange time of the whole bay is about 23 days, and the exchange time of 95% water body is about 60 days. The evaluation of MEC cannot only provide technical support for the offshore aquaculture industries but also provide a scientific basis for the total control of terrigenous pollutants in coastal cities in Southern Zhejiang Province.

Many gas chromatography-flame ionization detection (GC/FID) studies are dealing with response behavior of analytes such as alcohols and alkanes. Studies in the field of liquid chromatography (LC)/FID mainly focused on volatile analytes. In contrast, studies on LC/FID by conveyor type interface covered high molecular weight non-volatile biopolymers, whereby no response factors were calculated. With this study, we fill the gap and present response factors of volatile and non-volatile analytes by LC/FID in terms of flow injection (FIA) measurements of the single compounds without an analytical separation by an LC column. In the present study, 56 different compounds such as carboxylic acids, N-heterocycles, halogenated acids, pharmaceuticals, and other compounds were investigated. In some cases, the obtained response factor data confirmed aspects known from GC/FID studies. But this study also disproves several assumptions done in previous response studies as well as the prediction models based upon the experimental data and literature. Especially the response factors and effective carbon number (ECN) values of structural isomers such as pyrazine, pyridazine, and pyrimidine are assumed to be equal in current response prediction models. Contradictory to these assumptions, the experimental response factors and ECN values of, e.g., the structural isomers pyrazine (RFExp = 0.59; ECNExp = 3.66), pyridazine (RFExp = 0.66; ECNExp = 4.1), and pyrimidine (RFExp = 0.63; ECNExp = 3.93) reveal different experimental response factors and ECN than proposed by response factor prediction models (RFExp = 0.64; ECNExp = 4). [ABSTRACT FROM AUTHOR]

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]

For the quantitative analysis of volatile organic compounds (VOC), the use of a proper solvent is crucial to reduce the chance of biased results or effect of interference either in direct analysis by a gas chromatograph (GC) or with thermal desorption analysis due to matrix effects, e.g., the existence of a broad solvent peak tailing that overlaps early eluters. In this work, the relative performance of different solvents has been evaluated using standards containing 19 VOCs in three different solvents (methanol, pentane, and hexane). Comparison of the response factor of the detected VOCs confirms their means for methanol and hexane higher than that of pentane by 84% and 27%, respectively. In light of the solvent vapor pressure at the initial GC column temperature (35°C), the enhanced sensitivity in methanol suggests the potential role of solvent vapor expansion in the hot injector (split ON) which leads to solvent trapping on the column. In contrast, if the recurrent relationships between homologues were evaluated using an effective carbon number (ECN) additivity approach, the comparability assessed in terms of percent difference improved on the order of methanol (26.5%), hexane (6.73%), and pentane (5.24%). As such, the relative performance of GC can be affected considerably in the direct injection-based analysis of VOC due to the selection of solvent.

We studied the effect of 1-glyceryl monooleate additions on the response factor and linearity range of the analytical signal in the determination of trace amounts of 56 pesticides of various classes (amides, carbamates, imidazoles, morpholines, pyrazoles, pyrimidines, triazoles, etc.) by gas chromatography with mass spectrometric detection. An optimal concentration range of 1-glyceryl monooleate was found, which, simultaneously with improving the shape of the chromatographic peak (increasing height, decreasing broadening), ensures the expansion of the concentration limit of the signal linearity and lowers the limit of detection for pesticides in their determination in agricultural products. In contrast to the currently used sorbitol, D(+)-gluconic acid δ-lactone, and shikimic acid, 1-glyceryl monooleate exhibit better thermal stability under gas-chromatographic determination (in helium medium) and better solubility in organic solvents, especially, in nonpolar ones (hexane). The use of 1-glyceryl monooleate as an addition reduces the contamination of the liner of the chromatograph injector and column, eliminates the instability of substance concentrations in the solution and a possibility of their precipitation, and minimizes the likelihood of the syringe plunger rod getting stuck when the sample is injected. Thus, there is no need to flush the syringe thoroughly with water or an aqueous-organic mixture after each injection. [ABSTRACT FROM AUTHOR]

The abundance of an ion in an electrospray ionization mass spectrum is dependent on many factors beyond just solution concentration. Even in cases where the analytes of interest are permanently charged (under study here are ammonium and phosphonium ions) and do not rely on protonation or other chemical processes to acquire the necessary charge, factors such as cation structure, molecular weight, solvent, and the identity of the anion can affect results. Screening of a variety of combinations of cations, anions, and solvents provided insight into some of the more important factors. Rigid cations and anions that conferred high conductivity tended to provide the highest responses. The solvent that most closely reflected actual solution composition was acetonitrile, while methanol, acetonitrile/water, and dichloromethane produced a higher degree of discrimination between different ions. Functional groups that had affinity for the solvent tended to depress response. These observations will provide predictive power when accounting for analytes that for reasons of high reactivity can not be isolated. [ABSTRACT FROM AUTHOR]

Carbohydrate conversion offers access to a variety of chemicals with diverse functionalities. An accurate analysis of the multiple products in post-reaction material is indispensable for enabling good atom economy in biorefining. A certain need for reconsidering current analytical approaches to chemocatalytic biomass conversion is witnessed by the often poor carbon balances that are reported for carbohydrate conversion processes. Carbohydrate conversion usually includes isomerization and/or dehydration, therefore analytical approaches that are suitable for the distinction and concurrent quantification of isomers are desirable for developing sustainable processes towards known and new chemicals. Quantitative 1D NMR spectroscopy can be used to determine absolute concentrations in the absence of purified reference compounds and can thereafter be used to obtain response factors in other analytical methods resolving the compounds of interest. Here, we show that this approach is applicable for obtaining response factors relative to an internal standard for rapid, highly resolved 2D NMR spectra at natural isotopic abundance. Following calibration, this approach provides a limit of quantification in the order of 0.8 mM within an experiment time of a few minutes. The approach is particularly beneficial for the quantification of compounds at low concentrations, for instance in initial rate experiments, and for the quantification of low populated reaction intermediates. [ABSTRACT FROM AUTHOR]

Formulas for calculating relative response factors (RRFs) and correction factors (Fs) of impurities and those necessary for understanding the essence of RRFs and Fs are presented. The main methods for determining Fs and their limitations (conditions necessary for correct determination of RRFs and Fs) are considered. These limitations do not appear in the European and US pharmacopoeias although they must be considered to determine the correct Fs. Examples and recommendations are given for reliable determination and correct use of the Fs. [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]

Paralytic shellfish toxins (PSTs) are a complex class of analogs of the potent neurotoxin saxitoxin (STX). Since calibration standards are not available for many PSTs, including C-11 hydroxyl analogs called M-toxins, accurate quantitation by liquid chromatography–mass spectrometry (LC-MS) can be challenging. In the absence of standards, PSTs are often semiquantitated using standards of a different analog (e.g., STX), an approach with a high degree of uncertainty due to the highly variable sensitivity between analytes in electrospray ionization. Here, relative molar response factors (RMRs) were investigated for a broad range of PSTs using common LC-MS approaches in order to improve the quantitation of PSTs for which standards are unavailable. First, several M-toxins (M1-M6, M9 and dcM6) were semipurified from shellfish using preparative gel filtration chromatography and quantitated using LC-charged aerosol detection (LC-CAD). The RMRs of PST certified reference materials (CRMs) and M-toxins were then determined using selective reaction monitoring LC-MS/MS and full scan LC-high-resolution MS (LC-HRMS) methods in positive and negative electrospray ionization. In general, RMRs for PSTs with similar chemical structures were comparable, but varied significantly between subclasses, with M-toxins showing the lowest sensitivity. For example, STX showed a greater than 50-fold higher RMR than M4 and M6 by LC-HRMS. The MS instrument, scan mode and polarity also had significant impacts on RMRs and should be carefully considered when semiquantitating PSTs by LC-MS. As a demonstration of their utility, the RMRs determined were applied to the semiquantitation of PSTs in contaminated mussels, showing good agreement with results from calibration with CRMs.

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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]

Purpose To investigate the energy dependence/spectral sensitivity of silicon diodes designed for small-field dosimetry and obtain response factors (RFs) for arbitrary photon spectra using Monte Carlo (MC) simulations. Methods The EGSnrc user-code DOSRZnrc was used to calculate the dose deposition in water and in the active volume of a stereotactic diode field detector (SFD). Then, the RFs of the SFD were calculated for several circular field sizes and energies at 5 cm depth in water. Several low-energy photon spectra (mean energy 55 to 200 keV), as well as Co-60 radiation (mean energy 1.25 MeV) and a 6 MV Elekta Synergy beam (mean energy 2.9 MeV), in 10 × 10 cm2 field size were used to validate the MC calculations, using a simple beam model. The RFs of the SFD detector for a 6 MV Elekta Synergy linac photon beam in different field sizes were calculated. These were also measured with EBT3 Gafchromic film and the SFD detector. Results For the reference field size, differences between measured and calculated RFs were less than 5% at mean energies below 1 MeV and less than 1% at energies above 1 MeV. The calculated RFs for a 6 MV Elekta Synergy linac photon beam as a function of different field sizes showed a good agreement between the measurements and previously reported results. This agreement was within 2% for all considered field sizes. Conclusion While at high photon energies, the change of response of the SFD is marginal, whereas it is extreme at low energies. Therefore, it is desirable to benchmark response calculations also in the low-energy domain. Our results, with a simple beam model and geometry, indicate that a validation of the simulations by experimental results is achievable. The present work provides a comprehensive table that can be used to calculate SFD detector response factors depending on both, field size and photon energy. [ABSTRACT FROM AUTHOR]

Ground heat exchanger (GHE) is an important component of ground-coupled heat pump system. The soil temperature distribution and heat exchange capacity of GHE will largely determine the overall performance of the system. Consequently, it is very important for system design and its further performance improvement to seek a proper method of calculating the soil temperature field around GHE and the corresponding heat exchange rate. To break the limits of the existing calculating solutions and to improve the calculation accuracy and speed simultaneously, a fast distributed parameter model based on response factor (RF model) was proposed in this paper. The response factor refers to the contribution of a heat source to the excess temperature variation of a certain soil point. In a case study, the response factors and the temperature distribution of the soil heat container around one borehole were calculated using the RF model. Compared with results of numerical simulations, it can be known that the RF model equaled numerical solution in terms of accuracy, but enjoyed faster speed over numerical solution. In addition, the RF model was validated against the experiment data, with deviations less than 1.2%. In conclusion, the proposed RF model was a potential solution to predict the transient soil temperature distribution fast and accurately. [ABSTRACT FROM AUTHOR]

Lignin structural studies play an essential role both in understanding the development of plant cell walls and for valorizing lignocellulosics as renewable biomaterials. Dimeric products released by selectively cleaving β-aryl ether linkages between lignin units reflect the distribution of recalcitrant lignin units, but have been neither absolutely defined nor quantitatively determined. Here, 12 guaiacyl-type thioacidolysis dimers were identified and quantified using newly synthesized standards. One product previously attributed to deriving from β-1-coupled units was established as resulting from β-5 units, correcting an analytical quandary. Another longstanding dilemma, that no β-β dimers were recognized in thioacidolysis products from gymnosperms, was resolved with the discovery of two such authenticated compounds. Individual GC response factors for each standard compound allowed rigorous quantification of dimeric products released from softwood lignins, affording insight into the various interunit-linkage distributions in lignins and thereby guiding the valorization of lignocellulosics. [ABSTRACT FROM AUTHOR]

In this work, model results of the effect of thermal conduction on frequency response of a perturbed vaporizing spherical droplet are presented and discussed. The linear analysis of dynamic response to small acoustics oscillations are performed on the basis of the Rayleigh criterion for a mean spherical droplet representing the spray of repetitively injected droplets in the combustion chamber. Curves related to different heat exchange coefficients are presented for the frequency response of the vaporization rate. The not-yet-solved case of imposed temperature at the centre of the spherical droplet (isothermal centre regime or isothermal injection regime) is taking into account here. The case is now compared to the case where the feeding process at the centre of the spherical droplet is assumed adiabatic (adiabatic centre regime or adiabatic injection regime). Each feeding case here considered represents a specific boundary condition controlling the whole injection process. The temperature field perturbation inside the droplet is then examined. Comparisons are also made between the adiabatic and the isothermal injection regimes and differences are analysed. It is shown that the characteristic times of the evaporation process, the period of the harmonic perturbation and a particular parameter depending on fuel physical properties do intervene strongly in the behaviour of the vaporizing droplet. Especially, in the isothermal injection regime, due to this particular parameter, high and non-linear frequency responses may appear in the process. The results of this theoretical study may be applied in establishments of combustion systems stability limits. [ABSTRACT FROM AUTHOR]

For the quantitative analysis of volatile organic compounds (VOC), the use of a proper solvent is crucial to reduce the chance of biased results or effect of interference either in direct analysis by a gas chromatograph (GC) or with thermal desorption analysis due to matrix effects, e.g., the existence of a broad solvent peak tailing that overlaps early eluters. In this work, the relative performance of different solvents has been evaluated using standards containing 19 VOCs in three different solvents (methanol, pentane, and hexane). Comparison of the response factor of the detected VOCs confirms their means for methanol and hexane higher than that of pentane by 84% and 27%, respectively. In light of the solvent vapor pressure at the initial GC column temperature (35°C), the enhanced sensitivity in methanol suggests the potential role of solvent vapor expansion in the hot injector (split ON) which leads to solvent trapping on the column. In contrast, if the recurrent relationships between homologues were evaluated using an effective carbon number (ECN) additivity approach, the comparability assessed in terms of percent difference improved on the order of methanol (26.5%), hexane (6.73%), and pentane (5.24%). As such, the relative performance of GC can be affected considerably in the direct injection-based analysis of VOC due to the selection of solvent. [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]