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To investigate the quantitative relationship between ionic potential and coal ash fusibility, the chemical compositions and ash fusion temperatures (AFTs) of 214 coal ashes were tested. The prediction models of AFTs with the metal ionic potential concentration ( C M P = ∑ w i ∗ z i M i ∗ r i ∑ w i / M i ) were established by linear fitting. The mineral evolution under different CMP was calculated by FactSage 7.2. and was used to reveal the effect mechanism of CMP on AFTs. The results showed that AFTs initially emerged a negative correlation (24.13 nm−1

Refractive index measurements of sugar solutions have been carried out in several concentrations. The method used is fraunhofer diffraction. The equation of relationship between the concentration of the sugar solution and the refractive index based on the results of the linear fitting can be written as, Where n is the refractive index of the sugar solution and x is the solution concentration. From this equation, a fairly small gradient value of 1.59145 is obtained. This shows that a 1% increase in the concentration of the sugar solution will cause the refractive index to decrease by 1.59145. The refractive index of the solution changes when the concentration changes. The refractive index of the solution increases with increasing concentration of the solution. This is because along with the increase in concentration, more glucose is found in the sugar solution. As a result, the solution will be more concentrated because the glucose molecules that are arranged are getting denser. The above equation is used to calculate the concentration of sugar in sugar cane. It was found that brown sugar cane had a concentration of 33.38% compared to 26.34% in yellow sugarcane. While the measurement of the concentration of sugar cane in different planting areas shows almost the same results, this is because the level of accuracy of the tool is still large when compared to the difference in the concentration of the sugar solution.

A passive homodyne phase demodulation technique based on a linear-fitting trigonometric-identity-transformation differential cross-multiplication (LF-TIT-DCM) algorithm is proposed. This technique relies on two interferometric signals whose interferometric phase difference is odd times of π. It is able to demodulate phase signals with a large dynamic range and wide frequency band. An anti-phase dual wavelength demodulation system is built to prove the LF-TIT-DCM algorithm. Comparing the traditional quadrature dual wavelength demodulation system with an ellipse fitting DCM (EF-DCM) algorithm, the phase difference of two interferometric signals of the anti-phase dual wavelength demodulation system is set to be π instead of π/2. This technique overcomes the drawback of EF-DCM—that it is not able to demodulate small signals since the ellipse degenerates into a straight line and the ellipse fitting algorithm is invalidated. Experimental results show that the dynamic range of the proposed anti-phase dual wavelength demodulation system is much larger than that of the traditional quadrature dual wavelength demodulation system. Moreover, the proposed anti-phase dual wavelength demodulation system is hardly influenced by optical power, and the laser wavelength should be strictly limited to lower the reference error.

In this paper, spinyhead croaker (Collichthys lucidus) fat content forecasting model using electronic nose (e-nose) and non-linear stochastic resonance (SR) has been studied. Spinyhead croaker samples are stored at 4 °C temperature. Physical/chemical indexes (firmness, total volatile basic nitrogen (TVB-N), pH, and fat content) are examined to provide quality references for e-nose. E-nose responses are treated by principal component analysis (PCA), bistable SR, and double-layered cascaded serial SR (DCSSR). SR and DCSSR SNR maximal (SNR-Max) values discriminate croakers clearly. Multi-variables regressions (MVR) are conducted between physical/chemical indexes and SR/DCSSR SNR-Max values. MVR results demonstrate that DCSSR feature values have more significant linearity relation with physical/chemical indexes. Spinyhead croaker fat content forecasting model is developed via linear fitting regression on SR SNR-Max values. Validating experimental results demonstrate that the developed model has good accuracy.

In this paper, ridgetail white prawn (Exopalaemon carinicauda) K value predicting model by electronic nose (EN) was studied. Human sensory evaluation (HSE), weight loss, color, total viable counts (TVC), GC-MS, and K value were examined to provide quality references for EN detection. EN responses to prawns were recorded and processed by principal component analysis (PCA) and stochastic resonance (SR). Results indicated that prawn K value rapidly increased due to microbiology propagation. The volatile gases emitted by prawns increased with the increase of storage time based on GC-MS results. PCA method could not discriminate the prawns in different qualities, and SR signal-to-noise ratio (SNR) maximum (SNRmax) values successfully discriminated all samples. K value predicting model was developed by linear fitting regression between K values and SNRmaxvalues (R2 = 0.97). The proposed method will promote the applications of EN in aquatic product quality rapid determination.

In this study, changes in various states of water in apple cubes were assessed using low-field nuclear magnetic resonance (LF-NMR) during microwave vacuum drying. Apple cubes were dried at differen...

The interactions between elements such as Ca, Fe, Si, Na, Mg, Al, and S in a cement sample were analyzed using prompt gamma neutron activation analysis (PGNAA). The actual Ca, Si, and Fe contents in the cement sample and the measured values from the PGNAA were compared in terms of the interactions between the elements using a linear fitting technique, followed by applying a regression analysis correction. The results show that the linearly fitted graphs have more decentralized data points, with relatively larger errors in the measured Ca, Fe, and Si contents (maximum errors are 18.07, 1.68, and 18.47, respectively). However, the interactions between Ca, Fe, Si, Na, Mg, Al, S, and other elements were eliminated after applying the correction. Accordingly, the errors in the measured Ca, Fe, and Si contents were lower (maximum values are 0.97, 0.13, and 0.01, respectively). The correction method helps in improving the measurement accuracy.

A chairside tool for quantitative analysis of dental caries would improve clinical dental inspections. The wireless caries sensing tool with dental-explorer size has been developed comparing two sensing methods, Raman reading and pH reading for evaluating dental caries. The Raman spectra at 575 cm−1 and 960 cm−1 for in inorganic compounds, as well as 1450 cm−1 and 2940 cm−1 for organic compounds reinforced and supported the pH results. An Iridium/Iridium oxide (Ir/IrOx) pH sensing probe and wireless pH sensor (comprising an ESP8266 ESP-01 wireless module and ADS1115 analog digital converter) has been developed to quantitatively evaluate dental caries. All the operations of the wireless pH sensor were performed with a developed LabVIEW-based real-time data monitoring program. The slope and the linear fitting regression value (R2) of the wireless pH sensor using seven standards were −54.9 mV/pH and 0.999, respectively, showing high accuracy and stability for the pH measurements. The pH on the dental caries surface was measured with the wireless pH sensor, and the pH mapping results in the non-caries and caries areas were 6.9 and 5.7, respectively. The developed wireless pH sensor would be useful to understand the condition of dental caries and support dentists’ inspection to remove only the caries part while keeping the non-caries structure.

The purpose of this study is to clarify the degree of impregnation resulting from treatment of internal waterlogged wood samples using MRI. On a 1.5T MR scanner, T1 and T2 measurements were performed using inversion recovery and spin-echo sequences, respectively. The samples were cut waterlogged pieces of wood treated with various impregnation techniques which were divided into different concentrations of trehalose (C12H22O11) and polyethylene glycol (PEG; HO-(C2H4O)n-H) solutions. Then these samples underwent impregnation treatment every two weeks. From the results, we found that the slope of the T1-concentration curve using linear fitting showed the value of the internal area for PEG to be higher than the external area; internal, -2.73ms/wt% (R2=0.880); external, -1.50ms/wt% (R2=0.887). Furthermore, the slope of the T1-concentration curve using linear fitting showed the values for trehalose to have almost no difference when comparing the internal and the external areas; internal, -2.79ms/wt% (R2=0.759); external, -3.02ms/wt% (R2=0.795). However, the slope of the T2-concentration curve using linear fitting for PEG showed that there was only a slight change between the internal and the external areas; internal, 0.26ms/wt% (R2=0.642); external, 0.18ms/wt% (R2=0.920). The slope of the T2-concentration curve did not show a change in linear relationship between the internal and the external areas; internal, 0.06ms/wt% (R2=0.175); external, -0.14ms/wt% (R2=0.043). In conclusion, using visualization of relaxation time T1, it is possible to obtain more detail information noninvasively concerning the state of impregnation treatment of internal waterlogged wood.

Mitochondria are cellular energy factory, having an essential role in cellular metabolism. Furthermore, abnormal changes in mitochondrial viscosity have been confirmed to be closely related to many diseases. Therefore, the development of probe that responsive to mitochondrial viscosity and its application in mitochondrial viscosity measurement is considered to be a new tool for understanding diseases. In this paper, a mitochondrial viscosity probe (DICB) with a large Stokes shift (214–253 nm) was designed and synthesized by modifying the structure of the carbazole fluorophore. The probe DICB has a favorable responsive to viscosity in the near-infrared (NIR) region (703 nm). In the water-glycerol system (0.893 cP −945 cP), the fluorescence intensity of DICB at 703 nm has a 74 times increase; in the range of 5.041 cP-856.0 cp, it has a well linear fitting relationship. Meantime, the probe has excellent sensitivity to viscosity. The probe (DICB) has been confirmed to be able to detect changes of mitochondrial viscosity in cell models induced by nystatin, carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and lipopolysaccharide (LPS); it has also been validated that DICB can be used in the process of autophagy to monitor mitochondrial viscosity. More importantly, DICB can be applied to the detection of abnormal mitochondrial viscosity in inflammatory tissues at the biological level. The outstanding characteristics of DICB for mitochondrial viscosity detection are not only of great importance to the development of viscosity probes, but also provides a universal strategy to study the relationship between inflammatory and mitochondrial viscosity.

In this paper, a portable electronic nose (E-nose) system was designed, and its application in K value prediction for large yellow croaker (Pseudosciaena crocea) was also explored. E-nose responses to croaker samples were measured for 8 days. Microbiological and chemical indexes including total viable count (TVC), K value, and GC-MS were synchronously examined. Principal component analysis (PCA) and stochastic resonance (SR) were utilized for E-nose measurement data analysis. Results suggested that croaker’s K value increased rapidly due to microbial propagation. GC-MS results presented the information of volatile gas emitted by croaker samples, and provided reliable references for E-nose responses. PCA method could not discriminate all croaker samples, while SR signal-to-noise ratio (SNR) maximum (Max SNR ) values quantitatively discriminated all samples. Large yellow croaker K value predictive model was developed by linear fitting regression between K values and Max SNR values with a regression coefficient (R 2 ) of 0.96. Validating experiment results demonstrated that the forecasting accuracy of this model is 83 % the regression coefficient of the developed model was 0.83. E-nose is a useful tool for food quality examination. But, there are no such standard references for E-nose examination, which limits the applications of this technique. The method proposed here will promote the applications of E-nose in aquatic product quality rapid analysis.

The thicknesses of a series of ultra-thin HfO2 films were precisely determined by mutual calibration by XPS and XRR in recent CCQM pilot study P-190. From these well-defined reference film thicknesses, the measurement capability of medium-energy ion scattering spectroscopy (MEIS) for the thickness of HfO2 films was investigated. The film thicknesses determined by MEIS showed a small difference, within 2%, from the reference thicknesses and an offset value of 0.017 nm. The MEIS thicknesses can also be determined by mutual calibration between the TEM thicknesses and the MEIS intensity ratios in the region of the substrate and HfO2 film. From linear fitting with the reference thicknesses, the MEIS thicknesses determined by mutual calibration showed a slope value of 1.011 and an offset value of 0.015 nm. As a result, MEIS can be a traceable method to determine the absolute thickness of ultra-thin HfO2 films and an offset traceable method for application of the mutual calibration method.

Gas phase heats of formation (HOF) of 18 kinds of 390 organic compounds were calculated by quantum chemical calculation using semi-empirical PM3, PDDG and PM6 methods. The calculated HOFs were compared with the experimental data to illustrate the accuracy for different kinds of organics. Furthermore, the calculated values were linearly fitted with experimental values using the least square method, and were afterward substituted into the fitted regression equations to obtain the calibrated ones. The results show that, for 10 kinds of the selected organics, PM6 is more accurate, and PDDG is more accurate for 7 kinds of organics, while PM3 is only good for amino acid. As a whole, PM6 predicts the HOFs more accurately, with its weighted total mean average deviation (WTMAD) being 0.4 kJ/mol and 2.4 kJ/mol smaller than those of PM3 and PDDG, respectively. On the other hand, our results show that PDDG is the best to differentiate the isomers, with its mean average deviation (MAD) for isomerization energy being 7.8 kJ/mol and 11.0 kJ/mol smaller than PM6 and PM3, respectively. After the calibration, the values of MADs from the PM3, PDDG and PM6 results for most organics are reduced by 0.1 to 18.2 kJ/mol, with exceptions of the PM3 for amines, PDDG for carboxylic acids, and PM6 for ethers.

A beef strip loins (Musculus longissimus lumborum) freshness determination method utilizing electronic nose (e-nose) was investigated in this paper. Fresh beef strip loins samples were stored at 4°C continuously for 10 days. Total viable count (TVC) index, total volatile basic nitrogen (TVB-N) index, and e-nose responses to beef strip loins samples were measured every day. TVC and TVB-N index rose with the increase of storage time. Principal component analysis (PCA) only partially discriminated beef samples under different storage days. Stochastic resonance (SR) signal-to-noise ratio (SNR) spectrum discriminated all beef samples successfully. Beef strip loins freshness discrimination model was developed using SR SNR maximums (SNRmax) linear fitting regression. The proposed method forecasted beef freshness with high accuracy. It is holds promise in meat freshness determination applications.

Carrier lifetimes in 6H-SiC epilayers were investigated by using numerical simulations and micro-wave photoconductivity decay measurements. The measured carrier lifetimes were significantly increasing with an increased thickness up to 200 μm while it stays almost constant in layers thicker than 200 μm. From a comparison of the simulation and experimental results, we found that if the bulk lifetime in 6H-SiC is around a few microseconds, both the surface recombination and interface recombination influence the carrier lifetime in layers with thickness less than 200 μm while only the surface recombination determines the carrier lifetime in layers with thickness more than 200 μm. In samples with varying thicknesses, a bulk lifetime = 2.93 μs and carrier diffusion coefficient D= 2.87 cm2/s were derived from the linear fitting of reciprocal lifetime vs reciprocal square thickness.

The electrical properties of Ag Schottky contacts to hydrothermally-grown polar (Zn- and Opolar) and nonpolar (m-plane) bulk ZnO were investigated. Ohmic-like behavior for Zn-polar ZnO and rectifying behaviors for O-polar and m-plane ZnO were observed from current-voltage (I–V ) measurements. Schottky contacts to O-polar ZnO were found to have higher barrier heights and lower ideality factors than those to m-plane ZnO. Higher series resistances were found for both the Zn-polar and the m-plane ZnO compared to the O-polar ZnO probably due to the presence of the interfacial layer and interface states. The homogeneous barrier heights obtained from linear fitting to the effective barrier height vs. ideality factor plots were similar to those obtained from capacitance-voltage (C–V ) measurements. A higher degree of oxidation at the Ag-ZnO interface might occur for O-polar ZnO than for m-plane ZnO, increasing the barrier heights. The large dispersion in the capacitance for m-plane ZnO was related to the excess capacitance due to the interface states.

In the paper, Fourier transform infrared spectroscopy combined with Gaussian function linear fitting is used to analyze the structure of the viscoelastic scum formed during solvent extraction of sulfuric acid with trioctylamine (TOA). The results show that when the molar ratio of sulfuric acid to TOA is low in the system, it would form N⋯H O through TOA coupling with sulfuric acid or TOA coupling with water. The N⋯H stretching vibration is around 3400 cm −1 . With the increase of molar ratio of sulfuric acid to TOA, three peaks, near 2660 cm −1 , 2610 cm −1 , and 2535 cm −1 , appear in the infrared spectrum and they are assigned to N H + combining with water, N H + combining with O S , N H + combining with water and O S in the extraction system. The wave-number of C N stretching vibration increases with the increase of molar ratio of sulfuric acid to TOA.

The solubilities of CO2 in solvent poly(ethylene glycols) (PEGs) with molecular weights of 150, 200, 300, and 400 were measured over the range of pressure from (100 to 1200) kPa and temperature from (303.15 to 333.15) K. Henry's constant was obtained by linear fitting of the experimental data, and thermodynamic properties of solutions were calculated from the correlation of Henry's constant. It indicates that the solubility of CO2 increases with increasing molecular weights of PEGs. Henry's constant based on mole fraction and the molality of CO2 in PEG400 vary from (4.78 to 7.09) MPa and (1.56 to 2.48) MPa·kg·mol–1 from (303.15 to 333.15) K, respectively.

The time and height at the peak maximum are key parameters to describe a chromatographic peak with prediction or optimization purposes, or in the qualitative/quantitative analysis of samples. Three different approaches to estimate these parameters, using the experimental points in the peak maximum region, are here described and compared. The approaches are based on the reliable description of the peak profile using a modified Gaussian model with a parabolic variance (PVMG). In the first approach, non-linear fitting of the chromatographic data to the PVMG model is carried out to obtain the time and height at the peak maximum (Approach I). In the other two approaches, the PVMG model is linearized to carry out a linear fitting. In each case, the optimal number of processed points was assessed. The three approaches yielded highly satisfactory results, being Approach I the best in terms of accuracy and robustness. The assessment of the accuracy in the estimations was carried out using simulated peaks. These peaks were built with the parameters obtained from real peaks for several probe compounds eluted under reversed-phase liquid chromatographic (RPLC) conditions, to which noise was added.

Delayed fluorescece(DF) is intrinsically related to the photosynthesis process,and it is a good method of researching the effect of various chemical and physical factors in vivo and in vitro on photosynthetic performance of plants.In this paper,the detection of DF emission spectra under the stress(heat,salt and UV-B) have been investigated in maize(98-2) sample.The maximal values of DF emission spectra at 685 nm and 730 nm were marked as F685 and F730 respectively.After comparative measurement of F730/F685 ratio,DF intensity and Fv/Fm,the linear fitting results shown that the two parameters has a good linear correlation(R2≥0.960 9).The experimental results suggest that the degree of plant photosynthetic physiology damage whether caused by different concentration or different stress time can be effectively measured by F730/F685.Moreover,the responses of F730/F685 ratio of DF emission spectra to the stress could be a new and useful judgment to identify and evaluate the stress damage of the samples.

The Ti oxidation state of a series mixed-valence BaTi1−xNbxO3 compound (where x=0.002, 0.004, 0.02, 0.10, 0.20 and 0.50) is investigated using high resolution electron energy loss spectroscopy (EELS). The energy loss near edge structure (ELNES) of the Ti-L2,3 and O-K edges was recorded with high energy resolution. The fraction of Ti4+ and Ti3+ components is determined in each compound by linear profile fitting with Ti4+ and Ti3+ standard spectra obtained from reference compounds within the series. The fitting results indicate an increase in the fraction of the Ti3+ component as the Nb content increases. A deviation from the expected Ti3+ valence fraction based on the charge balance across the series was detected and discussed. By considering all detailed features on the spectra obtained with high energy resolution, this linear fitting method can be used to determine the oxidation state of transition metal oxides, especially for the early transition metals where conventional methods based on the L2,3 edge ratio have shown to fail. The potential of this method to provide insight to mixed valence systems, vacancies and properties of oxides is discussed.

Fe 2 O 3 nanorods were synthesized in large scale by a typical surfactant-free hydrothermal method. The electrical property of a single nanorod was investigated between two gold nanoelectrodes. Nonlinear I–V curves were got under different temperatures and pressures respectively as the bias ranged from –3 V to 3 V. Such a nonlinear electrical behavior was attributed to the existence of barriers. And the barrier height was estimated to be 0.13 eV by linear fitting ln( I / T 2 ) and (− 1/ kT ). The effect of oxygen pressure to the conductance is due to the conversion from depletion layer to inversion layer caused by the oxygen-controlled surface potential as well as the small size of the nanorods.

Over 90 % of diabetic patients have Type 2 diabetes. Although an elevated mean breath acetone concentration has been found to exist in Type 1 diabetes (T1D), information on breath acetone in Type 2 diabetes (T2D) has yet to be obtained. In this study, we first used gas chromatography–mass spectrometry (GC–MS) to validate a ringdown breath-acetone analyzer based on the cavity-ringdown-spectroscopy technique, through comparing breath acetone concentrations in the range 0.5–2.5 ppm measured using both methods. The linear fitting of R = 0.99 suggests that the acetone concentrations obtained using both methods are consistent with a largest standard deviation of ±0.4 ppm in the lowest concentration of the range. Next, 620 breath samples from 149 T2D patients and 42 healthy subjects were collected and tested using the breath analyzer. Four breath samples were taken from each subject under each of four different conditions: fasting, 2 h post-breakfast, 2 h post-lunch, and 2 h post-dinner. Simultaneous blood glucose levels were also measured using a standard diabetic-management blood-glucose meter. For the 149 T2D subjects, their exhaled breath acetone concentrations ranged from 0.1 to 19.8 ppm; four different ranges of breath acetone concentration, 0.1–19.8, 0.1–7.1, 0.1–6.3, and 0.1–9.5 ppm, were obtained for the subjects under the four different conditions, respectively. For the 42 healthy subjects, their breath acetone concentration ranged from 0.1 to 2.6 ppm; four different ranges of breath acetone concentration, 0.3–2.6, 0.1–2.6, 0.1–1.7, and 0.3–1.6 ppm, were obtained for the four different conditions. The mean breath acetone concentration of the 149 T2D subjects was determined to be 1.5 ± 1.5 ppm, which was 1.5 times that of 1.0 ± 0.6 ppm for the 42 healthy subjects. No correlation was found between the breath acetone concentration and the blood glucose level of the T2D subjects and the healthy volunteers. This study using a relatively large number of subjects provides new data regarding breath acetone in diabetes (T1D and T2D) and suggests that an elevated mean breath acetone concentration also exists in T2D.

Analytical applications of SERS are often more associated with qualitative than quantitative analysis, because of the difficulty in obtaining quantitative SERS results. In this paper we introduce a new strategy to quantitatively measure the SERS signals of analytes based on Au-core/Ag-shell nanoparticles with embedded 4-aminothiophenol as the internal reference. Successful detections of two analytes, Toluidine Blue O in aqueous solution (detection limit of 0.1 μM) and melamine in milk (detection limit of ~5 μM), are demonstrated. The improvement in the linear fitting illustrates that the use of internal reference significantly improves the accuracy of the quantitative SERS measurements. The successful detection of melamine in milk illustrates the versatility of this detection scheme for a wide variety of analytes.

Two self-normalized photothermal techniques, to carry out thermal diffusivity measurements of condensed phase materials, are presented. These simple methodologies involve linear fitting procedures of the signal amplitude and phase. These procedures lead to the elimination of the usual requirement for instrumental transfer-function normalization. The thermal diffusivities for two dental resins and two pure liquids are measured with these simple methodologies and very good agreement is found with values reported in the literature, where more involved analysis is usually required.

A method for the p K a determination, based on mobility data measured by capillary zone electrophoresis, was applied to cytokinins and their analogs. The combination of charged mobility standards with an uncharged electroosmosis marker, injected in the uncoated capillary simultaneously with the measured substances, allows one to minimize the number of runs, reduce their duration and, in addition, to inform on the run-to-run stability of electroosmosis and on contingent side-effects. p K a values of investigated cytokinins and their analogs ranged from 2.8 to 4.0 at 25°C in the phosphate and acetate buffers of ionic strength 0.015 M . Standard deviations of the constants, obtained by the non-linear fitting of equations for the p K a calculation, were 3–5-times lower than standard deviations from the linear fitting or from the point-to-point calculation utilizing the Hendersson–Haselbalch equation. The equation of Boltzman sigmoid offers two checks on reliability of effective mobilities that serve as the raw data in the p K a calculation.

A simple and efficient method has been proposed for the preparation of octyl-sulfonic co-bonded silica (OSS) packing by the method of "mixed ligand". The resulting OSS packing was characterized by elemental analysis and ion-exchange capacity to prove the successful immobilization of octyl and sulfonic groups on the surface of silica gel. Then the retention mechanism of several basic analytes on the developed OSS phases was evaluated under the conditions of reversed-phase liquid chromatography (RPLC) mobile phase. The results indicated that the OSS stationary phases demonstrated a mixed-mode reversed-phase/strong-cationic-exchange (RP/SCX) retention mechanism and ion-exchange interaction maybe dominate the retention of the basic analytes. By changing the salt concentration of mobile phase, the one-site and two-site mixed-mode retention models of the several basic analytes on the OSS phases were obtained by investigating the logarithm and reciprocal relationships of retention factor and salt concentration. On the basis of the linear fitting of the two mathematical equations of the retention models, the experimental results demonstrated that the two-site model was more suitable for the description of the retention mechanism of the basic analytes on the OSS phases. Furthermore, the individual RP or SCX contribution to total retention was obtained according to the mathematical equations of the two-site retention mechanism, which can provide some valuable guidance for the separation of complex samples.

Alpha-synuclein is analyzed in physiological conditions by CLEANEX-PM methodology, in which the amide-proton exchange can be monitored at millisecond scale. The relationship between kex and [OH]− is confirmed as a linear correlation with slope 1, indicating EX2 regime. There are significant residual structures at the N- and C-terminal regions. The structure at the C-terminal region is more stable than that of the N-terminal region. The middle part including NAC region is not completely protected. The data acquired at various pH and mixing time conditions followed by linear fitting give accurate information about residual structures.

11 páginas, 4 tablas, 3 figuras, Despite the need to determine the concentration and conditional stability constants (K′) of natural ligands, we are far from achieving a consensus about the mathematical procedure to use with metal titrations due to the complexity of the samples and the wide range of fitting procedures and problems associated with the selection of the sensitivity (S) of the method. Here, we used Competitive Ligand Exchange/Adsorptive Cathodic Stripping Voltammetry (CLE/AdCSV) empiric data from estuarine waters and computer generated titration sets to compare linear methods with iterative correction of S with non-linear fitting adding S as a parameter. We demonstrate for the first time that, independent of the fitting procedure, S cannot be retrieved if all the ligands present in the sample are not included in the speciation model. We also investigated the variables, apart from analytical noise, that can cause flawed non-linear fittings of titration data. Computer generated data under multiple combinations of analytical conditions showed that a long extension of the titration (at least twice the total ligand concentration for estuarine conditions) and an analytical window (as the side coefficient ∝′) centered below the complexing strength of the natural ligands are essential to produce reliable complexing parameters. We verified, using for the first time a combination of experimental and computer generated data, that faulty estimations of S and K′ obtained in empiric titrations of estuarine samples were artifacts of non-linear fitting. Non-linear fitting flaws were caused by a combined effect of the analytical error, the analytical window and the ratio in between the copper concentration and the concentration of the strongest ligands. Here, we recommend for the study of estuarine waters to complement non-linear fitting with iterative linear fitting in order to avoid severe overestimations of S and the conditional stability constant of strong metal ligands., This work was funded by the MINECO of Spain (CGL2010-11846-E) and the Government of the Balearic Islands (project AAEE083/09). LML was supported by a Ramon y Cajal (MINECO) fellowship. J. Santos-Echeandía was funded with a JAE(CSIC) grant

Researchers have used scale-invariant bulk density, ρ, to estimate values of fractal dimension, D, for soil aggregate fragmentation. Justification for this assumption has not been fully explored. The objectives of this study were to compare values of D obtained using (i) scale-invariant and scale-variant ρ and (ii) linear (defined D l ) and nonlinear (defined D nl ) fitting procedures, and also (iii) to evaluate the influence of oily waste sludge incorporation on D. Aggregate ρ and mass-size distribution for a Meota loamy sand treated with different rates of an oily waste sludge were determined in the laboratory. Bulk density of soil aggregates, average size ranging from 0.21 to 9.55 mm, ranged from 1.15 to 1.37 Mg m -3 (R 2 = 0.91). Fifty-four values of D were obtained using the scale-variant or scale-invariant ρ for D l or D nl . Values of D l ranged from 2.23 to 3.83, and those of D nl from 2.07 to 3.15. The values of D obtained using the scale-variant ρ were always smaller than those obtained using the scale-invariant ρ. A switch from linear to nonlinear fitting resulted in significantly smaller values of D (D l ≥ D nl ). Oily waste sludge incorporation resulted in marked reductions in D l (R 2 = 0.88) or D nl (R 2 = 0.88). The results show the values of D obtained using nonlinear fitting and scale-variant ρ are accurate and smaller than those obtained using nonlinear or linear fitting or scale-invariant ρ or a combination of the latter three.

According to the operating specifications of existing electric field measuring instruments, measuring technicians must be located far from the instruments to eliminate the influence of the human body occupancy on a spatial electric field. Nevertheless, in order to develop a portable safety protection instrument with an effective electric field warning function for working staff in a high-voltage environment, it is necessary to study the influence of an approaching human body on the measurement of an electric field and to correct the measurement results. A single-shaft electric field measuring instrument called the Type LP-2000, which was developed by our research team, is used as the research object in this study. First, we explain the principle of electric field measurement and describe the capacitance effect produced by the human body. Through a theoretical analysis, we show that the measured electric field value decreases as a human body approaches. Their relationship is linearly proportional. Then, the ratio is identified as a correction coefficient to correct for the influence of human body proximity. The conclusion drawn from the theoretical analysis is proved via simulation. The correction coefficient kb = 1.8010 is obtained on the basis of the linear fitting of simulated data. Finally, a physical experiment is performed. When no human is present, we compare the results from the Type LP-2000 measured with Narda EFA-300 and the simulated value to verify the accuracy of the Type LP-2000. For the case of an approaching human body, the correction coefficient kb* = 1.9094 is obtained by comparing the data measured with the Type LP-2000 to the simulated value. The correction coefficient obtained from the experiment (i.e., kb*) is highly consistent with that obtained from the simulation (i.e., kb). Two experimental programs are set; under these programs, the excitation voltages and distance measuring points are regulated to produce different electric field intensities. Using kb = 1.9094, the corrected measurement of electric field intensity can accurately reflect the original environmental electric field intensity, and the maximal error is less than 6% in all the data comparisons. These results verify the effectiveness of our proposed method.

Iodine values (IVs) of some biodiesel samples were analyzed using both 1H NMR and a standard iodometric method. 1H NMR was carried out with and without 1,4-dioxane as an internal standard (IS). The results obtained using 1H NMR with 1,4-dioxane as an internal standard showed better linear fitting and correlation with the iodometric method than NMR without the IS. The proposed 1H NMR_IS method allows determination of the IV using smaller samples than the iodometric method. Moreover, the determination can be carried out in less than 15 min, dramatically less than the time needed to carry out the iodometric method. Authors are grateful to the Ministerio de Medio Ambiente (Project Ref.: A323/2007/3-02.5) for the financial support. The authors are also grateful to Mr. Rafael Prims from Raluy S.L. for the biodiesel supply and to Albert Tomàs and Montserra Llovera for the IV determination by the iodometric method and for the acidic profile analyses

A simple linear fitting procedure for determining first-order rate constants from 2D NMR exchange spectroscopy in rapidly relaxing systems is presented. The method was used to obtain the first-order rate constants for halogen exchange in a mixture of BC13 and BBr3. The rate constants obtained in this manner are compared to the rate constants obtained using previously published methods that have typically been applied to spin-12 nuclei.

We present a novel algorithm for baseline estimation in CE. The new algorithm which we have named as accelerated multiple-pass moving average (AMPMA) is combined to three preexisting low-pass filters, spike-removal, moving average, and multi-pass moving average filter, to achieve real-time baseline correction with commercial instrumentation. The successful performance of AMPMA is demonstrated with simulated and experimental data. Straightforward comparison of experimental data clearly shows the improvement AMPMA provides to the linear fitting, LOD, and accuracy (absolute error) of CE analysis.

A highly sensitive fluorescent probe (1) based on styrylcyanine dye for Cu2+ and Pb2+ has been developed. Probe 1 exhibited fluorescent turn-off sensing ability to Cu2+. On the other hand, 1 displayed ratiometric fluorescent response towards Pb2+ with a distinct fluorescent color change from blue to orange. The 1H NMR titrations revealed that the fluorescent response of 1 to Cu2+ and Pb2+ is triggered by the interaction of the pyridine unit and the metal ion. Detection limits of 1 to Cu2+ or Pb2+ were calculated as 1.24 and 3.41 × 10−6 M, respectively, by standard deviation and linear fitting. Furthermore, 1 can also be used as a sensor for detection of Cu2+ and Pb2+ in a test strip.