Method For Direct Determination Research Articles

Total organic carbon quantification in soils and sediments: Performance test of a modified sample preparation method

The total organic carbon (TOC) concentration of particulate samples is a key parameter to characterize soils and sediments. To demonstrate the applicability and reliability of a modified sample preparation method for the direct measurement of TOC contents in suspended particulate samples, we analyzed five certified reference materials (CRMs) with varying TOC concentrations using a Shimadzu TOC-L CPH analyzer. Measured values were calibrated with a multi-point curve that cover the full range of the expected TOC concentrations and the results were validated using statistical values and measures. The method validation reveals that the measurements are accurate and precise for CRMs from marine and soil contexts, but show a low accuracy for the CRM containing polycyclic aromatic hydrocarbons (PAHs). This demonstrates the applicability and reliability of the modified preparation method for direct TOC determination of suspended particulate samples. Therefore, it is relevant for a broader community, beyond geosciences, and for users employing devices of other manufacturers to analyze TOC in suspended particulate samples.•Modified preparation method uses reduced sample weights and yields accurate and precise results.•Cost-efficient and environmentally friendly alternative: reduces waste by saving acid and ultrapure water.•Avoids incomplete dissolution of dolomite by heating acidified samples.

Measuring a Mass: The Puzzling History of an Elusive Particle

Since Pauli’s hypothesis of their existence in 1930, neutrinos never ceased to bring into play novel ideas and to add new pieces of physics in the whole picture of fundamental interactions. They are only weakly interacting and, at odds with Standard Model’s predictions, have a mass less than one millionth of the electron mass, which makes the investigation of their properties very challenging. The issue of the measurement of neutrino’s rest mass gained a wider and wider consensus since its discovery through neutrino oscillations in 1998. Various neutrino sources are available for experiments, ranging from nuclear collisions of cosmic rays in the Earth atmosphere and supernova explosions to neutrino beams produced by accelerators and power reactors. These suggest different approaches to the experimental detection and measurement of the absolute value of the neutrino mass. In this paper, we retrace the intriguing story of this endeavor, focusing mainly on direct mass determination methods. The puzzling issue of the nature of massive neutrinos is addressed as well with explicit reference to the phenomenon of double beta-decay as a viable experimental tool to discriminate between Dirac’s and Majorana’s nature.

Direct position determination of moving targets based on DOA

AbstractCompared with the traditional two‐step localization methods, the direct position determination (DPD) method is more robust at low signal‐to‐noise ratio. However, to guarantee the optimal location result, the computational complexity of DPD with grid search is too high, especially for moving targets. Therefore, a new DPD method is proposed for moving targets with low computational complexity. First, using a proposed cost function, the position information is obtained from the received array signals directly, which enhances the accuracy of localization. Second, utilizing the method of successional difference the velocity is extracted, which avoid the multi‐dimensional grid search and reduces the computational complexity. Simulation results demonstrate that the proposed method reduces the computational complexity greatly and outperforms the conventional methods.

The modified Mohr-Coulomb model considering softening effect and intermediate principal stress

Based on the Mohr-Coulomb model, a modified Mohr-Coulomb model that can consider both softening effect and intermediate principal stress effect was formed by introducing plastic internal variables that characterize material damage and a modified stress Rhodes angle. The modified model is numerically integrated by implicit algorithm, the physical meaning of the model parameters of the modified model is clarified, and the multivariate analysis and sensitivity analysis of the model parameters are carried out. Combined with the results of the gypsum triaxial test, the model parameters of the modified model were determined by the equation solving and RBF neural network optimization method, and the validity of the model was verified. The research results showed that: The modified model established can consider both the material softening effect and the influence of the intermediate principal stress. Compared with the traditional Mohr-Coulomb model, the calculation results of the modified model are more consistent with the test results qualitatively and quantitatively. The comprehensive use of direct determination, equation solving and RBF neural network optimization methods can effectively determine the model parameters of the modified model, and the determination process is relatively simple. It is suggested that this combined method can be used for subsequent determination of more complex constitutive model parameters. Compared with the traditional Mohr-Coulomb model, the modified model only needs one more true-triaxial test to determine the model parameters. In addition, the experience of using the parameters of the traditional Mohr-Coulomb model in a large number of engineering practices can be used to improve the model, so the modified model has great potential for engineering applications.

An efficient measure for controlling pollution in the dye industry: Experimental and DFT investigations on direct determination of 3-(N,N-diethylamino)acetanilide

The rapid expansion of the dye industry has led to severe environmental pollution. The lack of real-time direct determination methods for dye intermediates is a key factor in high pollution emissions and low product quality in the continuous synthesis of dyes. This study proposes an accessible, fast, and precise approach for the clean and direct determination of 3-(N,N-Diethylamino)acetanilide (DEAA), a dye intermediate used in the synthesis of the azo dye Disperse Violet 93:1. For precise DEAA quantification, we developed a multi-pathlength and multi-wavelength coupled differential photometric approach based on the absorption spectra characteristics of DEAA at various concentrations and optical pathlengths. A relatively stable analytical sensitivity (0.5671–66.2630) and a large concentration range of 0.01–11% were obtained. Compared to the traditional single-optical pathlength and single-wavelength quantification, this new method possessed 119 times higher sensitivity. The maximum quantitative relative error decreased from 9.17% to 2.44%. The orbital contribution and distinctive peak electronic excitation mechanism of DEAA were uncovered using TD-DFT. By comparing the oscillator strength and peak position variations between the target DEAA and coexisting sulfuric acid, the unique spectral behavior of DEAA, such as its high sensitivity and selectivity, was explained. In addition to providing a reference for real-time industrial dye and intermediate monitoring, this study lays the methodological groundwork for future research. In light of the new method's short time consumption and non-secondary pollution benefits, we further believe it will be crucial in controlling the industrial synthesis process in order to improve product quality, resource conversion efficiency, and effectively prevent excessive pollution generation.

Engineered 3D-printed poly(vinyl alcohol) vascular grafts: Impact of thermal treatment and functionalization

Cardiovascular diseases, a leading cause of global mortality, are driving increased demand for artificial blood vessels for surgical repair. This study discloses the fabrication of three-dimensional (3D)-printed small blood vessels as tissue-engineered grafts. Large-diameter artery and vein grafts are readily available in the market, but small-diameter blood vessels face issues due to the lack of suitable materials. Lysine-biofunctionalized and unmodified poly(vinyl alcohol) grafts (PVA grafts) (2 mm inner diameter and 3 mm outer diameter) suitable for veins and venules were designed using Fusion 360 software, Autodesk Fusion. The PVA channels were fabricated from the 3D virtual model through fused deposition modeling using a PVA filament. These channels underwent thermal treatment to adjust their crystallinity, chemical crosslinking, and functionalization to optimize their mechanical properties and biocompatibility. Crosslinking and biofunctionalization were assessed using Fourier-transform infrared spectroscopy with attenuated total reflectance, while X-ray diffraction and differential scanning calorimetry were utilized for structural analysis. PVA grafts were biologically tested using three specific types of cell cultures: bEnd.3 brain endothelial cells, L929 fibroblast cells, and U937 monocyte-like cells. The hemocompatibility of the optimized vascular grafts was evaluated using horse blood, following the guidelines outlined in ASTM F756-13 Standard Practice for Assessment of Hemolytic Properties of Materials. The direct method for hemoglobin determination was specifically employed. Additionally, we developed an external polyethylene terephthalate glycol (PETG) 3D-printed platform to house the PVA grafts in parallel. The assembled platform (PETG and PVA graft) was connected to both an inlet and an outlet to facilitate the passage of an aqueous flow through the internal section of the PVA grafts during a flow test conducted under simulated body conditions (vacuum and blood pressure: 40 mbar). The flow was induced by a vacuum pump connected to the outlet of the platform, while the inlet was connected to a feeding glass. In summation, we have established a suitable protocol for producing small vascular grafts and demonstrated that the optimization process could significantly affect graft properties.

Development and Validation of a RP-HPLC Method for the Simultaneous Determination of Silver Sulfadiazine and Sodium Hyaluronate in the Presence of Methyl and Propyl Paraben in a Pharmaceutical Cream for Burns.

A direct and precise isocratic RP-HPLC method for simultaneous determination of silver sulfadiazine (SSD) and sodium hyaluronate (SH) in the presence of methyl (MP) and propyl parabens (PP) was developed and validated. Agilent chromatograph with X-Select C18 column (250 × 4.6mm2, 5μm) was used. Chromatographic separation was achieved using a mobile phase consisting of acetonitrile and 0.05M phosphate buffer (pH5.0 to which added triethyl amine 0.5ml/L), at a ratio 35: 65v/v. Elution was used at flow rate of 1.0mL/min at ambient temperature with UV detection at 205nm. The retention times for SH, SSD, MP and PP were 1.49, 3.3, 6.7 and 19.5min, respectively. The presented chromatographic method was fully validated in accordance with ICH requirements, it was valid over linearity ranges of (0.80-100.00μg/mL) and (3.20-100.00μg/mL) for SSD and SH, respectively. Acceptable precision and accuracy were obtained for concentrations over the standard curve ranges and the sensitivity of the method, as the limits of detection and quantification for each active ingredient was also determined. The validated method was successfully applied for the quantification of SSD and SH in pharmaceutical cream formulation and the mean recovery %±SD were 100.93 ± 0.985 and 100.05 ± 0.668 for SSD and SH; respectively, indicating satisfactory accuracy of the method.

Eco-friendly assessment of turmeric-assisted approach in developing and validating a method for the quantification of atropine sulphate in bulk and tablet dosage form using UV–Visible spectrophotometry

The literature review uncovers the quantitative analysis of atropine sulfate using either direct determination methods or chemical derivatization techniques. However, in order to innovate upon traditional analytical approaches, an alternative method for estimating atropine sulfate was developed using the natural pH indicator turmeric. An economical and accurate chemical derivatization technique utilizing turmeric powder was devised for the quantification of atropine sulphate in both bulk and tablet dosage forms. The maximum absorption was identified at 600 nm, with a linear range spanning 0.5 – 2.5 µg/ml. The correlation coefficient (r) was calculated to be 0.9997±0.0006, demonstrating an exceptional level of linearity. Rigorous validation of the proposed method affirmed its simplicity, precision, accuracy, and rapidity in determining atropine sulphate in both its pure form and dosage forms. Additionally, the developed approach underwent assessment through the Analytical GREEnness Metric (AGREE), Green Analytical Procedure Index (GAPI), and Analytical Eco-scale Assessment (AES). The AGREE and AES scores were observed to be 0.78 and 96, respectively, signaling highly favorable eco-friendly outcomes.

Impact of Ginger Oleoresin on Leaf Tripe of Sapumhicha

The main objective of the study is to examine the impact of ginger on the leaf tripe of 'SapuMhicha'. SapuMhicha is a special dish consisting of buffalo leaf tripe stuffed with bone marrow; it is boiled and fried. This dish is popular in Kathmandu Valley, especially in Newar community. The use of ginger makes this dish tasty and hygienic. It is indigenous knowledge and practice; with this, it can be preserved for a certain time period. Ginger is valued in nutritional importance as it contains fiber. Ginger contributes to minimizing Microbial growth that helps to stimulate the digestive system. The use of ginger in a tripe recipe makes low microbial. This study focuses on this indigenous knowledge of how ginger enhances leaf tripe to use for a long time. The impact of ginger on leaf tripe is tested using the AOAC direct moisture determination method on different days from 1 to 16 at normal room temperature. The result was that the impact of ginger on tripe leaf was positive i.e. low microbial growth was noticed. The result showed that ginger enhances the shelf-life of tripe at room temperature as it can be stored for a certain period of time and remain suitable for use.

A method for direct determination of voltage dependent contact resistance and mobility of an organic field effect transistor

A method for direct determination of voltage dependent contact resistance and mobility of an organic field effect transistor

Simultaneous square wave voltammetric determination of two anti-inflammatory drugs using a bare carbon paste electrode

Background Diclofenac (DIC) is a nonsteroidal anti-inflammatory drug (NSAID) that is more potent than indomethacin. There is an extended-release form of this drug available for long-term treatment. Diflunisal (DIF) is a NSAID with less anticoagulant activity than aspirin. It is more potent than aspirin and is not converted to salicylic acid in vivo. Objectives A simple, direct, and sensitive method for the simultaneous determination of two types of NSAIDs, namely, diclofenac ‘DIC’ and diflunisal ‘DIF’ by square wave adsorptive anodic stripping voltammetry and applied at the same time in synthetic and pharmaceutical samples. Materials and methods In this method, both cited ingredients were oxidized by a bare carbon paste electrode (CPE) forming two well-separated peaks at the potential of 0.65 and 0.85 V, respectively, in 0.04 M universal buffer solution at pH 5 with 100 mV/s scan rate by square wave adsorptive anodic stripping voltammetry technique with an Autolab system of potentiostat/galvanostat. Results and conclusion The prepared sensor showed good linear regression curves over the concentration ranges of 1–6 and 5–25 μg/ml for DIC and DIF, respectively, while the detection limit ‘LOD’ and quantification limit ‘LOQ’ and were 0.204 and 0.68 μg/ml for DIC and 1.366 and 4.553 μg/ml for DIF, in turn. The cited sensor was applied with accurate and precise results for determining DIC and DIF at the same time in synthetic and pharmaceutical samples and gave close results in comparison with the official method, specifically by UV-high performance liquid chromatography.

A Direct Position Determination Method Using Distributed UAVs With Synchronization Error

A Direct Position Determination Method Using Distributed UAVs With Synchronization Error

Self-Position Awareness Based on Cascade Direct Localization Over Multiple Source Data

The global positioning system (GPS), which provides ubiquitous location-awareness with a constellation of satellites, has become an instrumental function of multiple mass-market applications. Satellite signals, however, may not be capable of penetrating obstacles in harsh environments (e.g., urban canyons, tree canopies, and flyovers). Hence, GPS may not provide adequate localization accuracy for applications like autonomous vehicles. Resorting to data fusion of heterogeneous signals emanating from multiple anchors, we advocate a self-localization method that provides accurate estimates of the vehicle position. To be more specific, several heterogenous emitters whose positions are known are used as anchors to determine the vehicle's position based on the weighted direct position determination (DPD) method that eliminates nonhomogeneity among different emitters. However, the weighted DPD method requires an exhaustive search of the parameter search space and is thus time-consuming. To reduce the computational burden, we propose a weighted cascade compensation estimator (WCCE) that is tailored for real-time tracking and self-localization. The proposed WCCE outperforms traditional DPD methods in terms of computational complexity while achieving nearly comparable localization accuracy. The effectiveness of the proposed method is corroborated by extensive simulated examples.

The electrocaloric effect of lead-free Ba1−yCayTi1−xHfxO3 from direct and indirect measurements

We report on the dielectric and electrocaloric properties of Ba1−yCayTi1−xHfxO3 for compositions 0.12 < x < 0.18 and y = 0.06, as well as x = 0.15 and 0 < y < 0.15, synthesized by the conventional solid-state reaction method. The addition of Hf/Ca broadens the ferroelectric-paraelectric phase transition while moving it toward room temperature. Two interferroelectric transitions are seen to converge, together with the ferroelectric–paraelectric phase transition, at ∼335 K for 0.12 < xc < 0.135 and y = 0.06. Consistent with the dielectric properties, the electrocaloric effect maximizes closer to room temperature with increasing Hf/Ca substitutions, which promote larger temperature spans. The electrocaloric responsivity gradually decreases from 0.2 to 0.1 K mm kV−1 with the addition of Hf/Ca. A homemade quasi-adiabatic calorimeter is employed to measure “directly” the electrocaloric data, which are also calculated from polarization-versus-electric-field cycles using “indirect” standard procedures. The comparison between measured and calculated values highlights the importance of having access to direct methods for a reliable determination of the electrocaloric effect.

A Low-Complexity Direct Position Determination Method Based on the Diffusion Strategy in Wireless Sensor Array Networks

A Low-Complexity Direct Position Determination Method Based on the Diffusion Strategy in Wireless Sensor Array Networks

Fast and low-cost method for direct and simultaneous determination of nitrogen and carbon in soybean leaves using benchtop and portable near-infrared devices.

The current techniques for determining carbon and nitrogen content to provide information about the nutritional status of plants are time-consuming and expensive. For this reason, the objective of this study was to develop an analytical method for the direct and simultaneous determination of nitrogen and carbon elemental content in soybean leaves using near-infrared spectroscopy and compare the performance of conventional (1100-2500 nm spectral range) and portable equipment (1100-1700 nm spectral range). Partial least-squares regression models were developed using 27 soybean leaf samples collected during the 2021 harvest and applied for the simultaneous determination of carbon and nitrogen in 13 samples collected during the 2022 harvest. The root-mean-square error of prediction values for nitrogen and carbon were low (2.42 g kg-1 and 4.37 g kg-1 respectively) for the benchtop method yielded low but higher for the portable method (3.82 g kg-1 and 10.7 g kg-1 respectively). The benchtop method did not show significant differences when compared with the reference method for determining nitrogen and carbon. In contrast, the portable methodology showed potential as a screening method for determining nitrogen levels, particularly in fieldwork. The methodologies evaluated in this study were implemented and evaluated under real crop monitoring conditions, using independent sets of calibration and prediction samples. Their utilization enables the acquisition of cost-effective, safe analytical data aligning with the principles of green analytical chemistry. © 2023 Society of Chemical Industry.

Analytical Methods Based on the Mass Balance Approach for Purity Evaluation of Tetracycline Hydrochloride.

Analytical methods based on the mass balance approach were developed for the purity evaluation of tetracycline hydrochloride, a representative salt compound used in pure veterinary drug analysis. The purity assignment method was used to quantify individual classes of impurities via independent analytical techniques. The mass fraction of the free base or salt form contained in a high-purity organic compound with a hydrochloride salt can be determined. The chloride content by ion chromatography-conductivity detector (IC-CD) and general classes of impurities, including structurally related impurities by liquid chromatography-ultraviolet (LC-UV) detector, water by Karl Fischer (KF) coulometric titration, residual solvents by headspace sampler gas chromatography/mass spectrometry (HS-GC/MS), and non-volatiles by thermogravimetric analyzer (TGA), were considered to calculate the purity of the mass fraction. The chloride content of the salt compound can be considered the main impurity in the mass fraction of the free base in the salt compound. A purity assay using quantitative nuclear magnetic resonance (q-NMR) as a direct determination method was performed to confirm the results of the mass balance method. The assigned purities of the tetracycline free form and its salt form in mass fraction were (898.80 ± 1.60) mg/g and (972.65 ± 1.58) mg/g, respectively, which are traceable to the international system of units (SI). Thus, the procedure for evaluating the purity of the free base and salt forms in the salt compound is newly demonstrated in this study.

Directional distance functions data envelopment analysis method with endogenous direction for target setting

The determination of reasonable improvement direction is the key difficulty of directional distance functions in data envelopment analysis target setting method, but there is no consensus direction determination method at present. This paper introduces the concept of minimizing the distance between decision-making units (DMUs) and production frontier for constructing a new endogenous mechanism of improvement direction, and the corresponding target setting method is constructed to setting target for DMUs, which is used to minimize the total projection distance between DMUs and their targets. In addition, the free direction and unit invariant of improvement direction are discussed for meeting the diverse needs of decision makers.

Experimental and theoretical investigations of the radiation-induced conductivity in spacecraft polymers at extremely low temperatures

Radiation-induced conductivity (RIC) of polyethyleneterepfthalate and polypiromellitimide has been studied experimentally and numerically in a broad time range from some microseconds to seconds at 103 K. It has been established that the charge carrier transport is dispersive with a low value of the dispersion parameter α (0.08–0.12). We have suggested a direct method of determination of the frequency factor of the Rose–Fowler–Vaisberg (RFV) model, which has been parameterized using computer simulations by the trial-and-error method. The main concern is a critical analysis of the existing theories of geminate recombination. It has been shown that the traditional RFV model is well suited to describe the RIC in studied polymers even at 103 K if due corrections to the notion of a free charge carrier and a non-Langevin bimolecular recombination have been made. The problem of a space charge field due to beam electrons stopped in a polymer sample, which is especially important at low temperatures, has been accounted for but not fully explained.

Development and validation of two analytical strategies for the determination of glucosides of acidic herbicides in cereals and oilseed matrices

The aim of the present research was the development and validation of a selective and reliable method for the indirect and direct determination of acidic herbicide glucosides. Enzymatic deconjugation was investigated as a mild alternative to harsh alkaline hydrolysis. Various enzymatic options for deconjugation were exploited. One out of nine tested specific enzymes proved to be practical and repeatable for different matrices and concentration ranges, leading to the complete deconjugation of the glucosides. The method was validated according to the SANTE/11312/2021 guideline for cereals and oilseeds and for a rice-based infant formula. Additionally, for four acidic herbicide glucosides available on the market, a quantitative method for direct determination of the intact glucosides was optimized and validated. In both methods, the average recoveries were within 70–120%. The limits of quantification (LOQ) achieved were 10 µg kg−1 and 2.5 µg kg−1 for the intact glucosides and the free acids in cereal and oilseeds. For the rice-based infant formula, the LOQ was 1 µg kg−1 (3 µg kg−1 for dichlorprop). To confirm its applicability, the deconjugation approach was tested for fifteen samples (cereals, oilseeds, and citrus) with incurred residues. Comparisons were made between the method without deconjugation, and two methods with deconjugation, the here proposed enzymatic deconjugation and the more commonly used alkaline hydrolysis. The inclusion of enzymatic deconjugation during sample preparation led to an increase up to 2.7-fold compared to analysis without deconjugation. Enzymatic deconjugation resulted in comparable results to alkaline hydrolysis for 13 out of 15 samples.Graphical