Direct Analysis Method Research Articles

Comparison of Untargeted and Markers Analysis of Volatile Organic Compounds with SIFT-MS and SPME-GC-MS to Assess Tea Traceability.

Tea is one of the most consumed beverages in the world and presents a great aromatic diversity depending on the origin of the production and the transformation process. Volatile organic compounds (VOCs) greatly contribute to the sensory perception of tea and are excellent markers for traceability and quality. In this work, we analyzed the volatile organic compounds (VOCs) emitted by twenty-six perfectly traced samples of tea with two analytical techniques and two data treatment strategies. First, we performed headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) as the most widely used reference method for sanitary and quality controls of food. Next, we analyzed the samples with selected-ion flow-tube mass spectrometry (SIFT-MS), an emerging method for direct analysis of food products and aroma. We compared the performances of both techniques to trace the origin and the transformation processes. We selected the forty-eight most relevant markers with HS-SPME-GC-MS and evaluated their concentrations with a flame ionization detector (FID) on the same instrument. This set of markers permitted separation of the origins of samples but did not allow the samples to be differentiated based on the color. The same set of markers was measured with SIFT-MS instrument without success for either origin separation or color differentiation. Finally, a post-processing treatment of raw data signals with an untargeted approach was applied to the GC-MS and SIFT-MS dataset. This strategy allowed a good discrimination of origin and color with both instruments. Advantages and drawbacks of volatile profiles with both instruments were discussed for the traceability and quality assessment of food.

Electrochemical Sensor Based on Crafted Thia Polymeric Crown Ether for Determination of Carbamazepine and Ephedrine

Background: Direct analysis methods are considered some of the best and easiest tools to quickly determine the amount of active drug in some pharmaceutical preparations. Objectives: In this study, an ion electrode is prepared to determine the concentration of a sample of ephedrine (Eph) and carbamazepine (CBZ) in the medicines produced by some companies directly. Methods: CBZ and Eph drugs ion-selective electrode (ISE) based on Thia polymeric crown ether (SPCE-CZB and SPCE-Eph) as membrane carrier in polyvinyl chloride (PVC) matrix was successfully fabricated for the determination of CBZ and Eph drugs. Results: The electrode exhibited a liner Nernstian slope response over the range of 1×10-1 to 1×10-6 M, and 1×10-5 to 1×10-1 with a slope of 28 and 33±2 mV per decade charge, respectively, by using dimethyl phthalate plasticizer and a detection limit of 1×10-9 M. The response time of the sensor was 10 s. The ISE showed a greater preference for CBZ and Eph over other drugs with good precision. Conclusion: The selectivity coefficients of some drugs ranged from 1×10-5 to 1×10-1. Meanwhile, SPCE-CZB (ISE) was successfully used as an indicator electrode for the potentiometric determination of the CBZ drug pharmaceutical formulas.

Accuracy-preassigned fixed-time synchronization of switched inertial neural networks with time-varying distributed, leakage and transmission delays

In this paper, the accuracy-preassigned fixed-time synchronization problem of a class of switched inertial neural networks with time-varying distributed, leakage and transmission delays is studied. To this end, a parameterized system solution-based direct analysis method is proposed for the first time. Unlike existing works, this method sets out from the definition of accuracy-preassigned fixed-time synchronization, and does not require variable substitution for inertial item or the construction of any Lyapunov–Krasovskii functional. This not only simplifies the proof process, but also reduces the computational complexity for solving synchronization conditions. Significantly, this paper introduced the time-varying leakage delay into switched inertial neural networks for the first time. Furthermore, the approach utilized in this manuscript stands apart from all previous techniques for achieving fixed-time synchronization. Finally, the reliability of the theoretical results is verified by numerical simulation.

Combination of Coevolutionary Information and Supervised Learning Enables Generation of Cyclic Peptide Inhibitors with Enhanced Potency from a Small Data Set.

Computational generation of cyclic peptide inhibitors using machine learning models requires large size training data sets often difficult to generate experimentally. Here we demonstrated that sequential combination of Random Forest Regression with the pseudolikelihood maximization Direct Coupling Analysis method and Monte Carlo simulation can effectively enhance the design pipeline of cyclic peptide inhibitors of a tumor-associated protease even for small experimental data sets. Further in vitro studies showed that such in silico-evolved cyclic peptides are more potent than the best peptide inhibitors previously developed to this target. Crystal structure of the cyclic peptides in complex with the protease resembled those of protein complexes, with large interaction surfaces, constrained peptide backbones, and multiple inter- and intramolecular interactions, leading to good binding affinity and selectivity.

Anthropometric Profile and Position-Specific Changes in Segmental Body Composition of Professional Football Players Throughout a Training Period.

Body and anthropometric profiles of football players vary depending on the physiological and technical demands imposed by different positions. The aim of this study was to evaluate the body composition of professional soccer players in relation to their position on the field during a training macrocycle. The Direct Segmental Multi-Frequency Bioelectrical Impedance Analysis method was used to analyze 58 players at six key moments of the macrocycle. The results show that body profiles are adjusted to the specific demands of each position. Midfielders showed the lowest muscle mass, while defenders showed many notable changes. In general, as the season progressed, all field players experienced an increase in trunk body fat. Fat and lean mass values of goalkeepers differed greatly from the rest. The greatest variations in body composition were observed during pre-season and transition in relation to variations in training load and competitive intensity. The results suggest that the phase of the macrocycle has a greater influence on these variations, although the physical characteristics of each position are relevant. Understanding these dynamics allows for the design of more personalized and efficient training programs to optimize the performance of footballers according to their roles and each stage of the season.

Direct ion chromatographic method for speciation micro analysis of arsenic forms in industrial samples with “rich” matrix composition

The speciation analysis of arsenic has consistently been a subject of great interest. However, it remains challenging to analyze complex matrix samples that contain both arsenic and interfering components. In this case, it can be hard to choose the right combinations of different instrumental methods, or a separation method followed by detection, which is usually done using a spectral approach (hybrid methods). In the production control of copper electrorefining, the determination of the concentration of As (III) and As (V) helps to improve the quality of the cathode copper produced. This work investigated the possibility of directly determining both arsenic forms and total As in an electrolyte bath using ion chromatography (IC) with conductometric detection. The use of the ion chromatographic approach for the determination of As(V) in complex matrix samples such as copper electrolyte must take into account the presence of potential interferences from anions such as sulphates, sulfites, selenites, selenates, etc. The results revealed that the method is accurate and precise, with As(V) quantification limits of 15 µg.L-1 and detection limits of 5 µg.L-1. This method is suitable for assessing various types of arsenic in the production of electrolytic copper, with the aim of replacing the current technique that requires liquid-liquid extraction and ICP-OES detection. This led to the following improvements: Enhanced efficiency: The method eliminates the need for extensive and time-consuming sample preparation for the initial separation of arsenic forms. At the same time, the method's characteristics are comparable to those of ICP-OES with liquid-liquid extraction, which is often used in the speciation analysis of arsenic. The method is environmentally friendly as it avoids the use of organic and poisonous extractants. The method can simultaneously analyze other anions (PO43-, SO42-, F-, Cl-, etc.) with arsenates with appropriate calibration.

Existence and Ulam stability of initial value problem for fractional perturbed functional q-difference equations

Abstract. In this work, we discuss the existence and uniqueness of solutions to the initial value problem for perturbed functional fractional q-difference equations involving q-derivative of the Caputo sense. By applying Banach contraction principle and Burton and Kirk’s fixed point theorems. Further, we present the Ulam-Hyers and Ulam-Hyers-Rassias stabilities results by using direct analysis methods. Finally, we give two examples illustrating of the results. Mathematics Subject Classification (2010): 26A33, 34A12, 39A13, 47H10. Keywords: Initial value problem, Caputo fractional q-derivative, Burton and Kirk’s fixed point theorem, Ulam-Hyers stability, Ulam-Hyers-Rassias stability.

Direct glycosylation analysis of intact monoclonal antibodies combining ESI MS of glycoforms and MALDI-in source decay MS of glycan fragments

Monoclonal antibody (mAb) glycoengineering has the potential to improve the efficacy of biopharmaceuticals by fine-tuning specific biological properties. Glycosylation analysis is key to monitoring the glycoengineering process. Various mass spectrometry (MS)-based methods are available to characterize mAb glycosylation at different structural levels, but comprehensive analysis is typically time-consuming and costly. Here, we present an approach that combines conventional intact mass measurement of glycoforms by direct infusion ESI-MS with an advanced MALDI-in-source decay FT-ICR MS method for direct analysis of glycans in intact mAbs, without the need for enzymatic release and separation. Using a sodium-doped MALDI matrix, glycans were directly released as ISD fragment ions from the intact mAbs during the ionization process. Measurement of 0,2A fragment signals yielded reproducible glycan profiles that were consistent with conventional methods, yet was achieved with unprecedented speed, providing complementary information to that obtained through intact mass measurement. The methods were applied to standard and glycoengineered trastuzumab and rituximab, allowing rapid glycosylation profiling and structural analysis of glycans by tandem MS of selected ISD fragment ions. This fast approach can facilitate the early-phase development of glycoengineering processes by constraining further in-depth analyses. We envision a broader applicability in studies focused on glycosylation changes in mAbs.

Quantifying the effects of chlorine disinfection on microplastics by time-resolved inductively coupled plasma-mass spectrometry

Using current water treatment systems, significant amounts of microplastics (MPs) are passing through and being released into the aquatic environment. However, we do not clearly know what effects disinfection processes have had on these particles. In this study, we applied inductively coupled plasma-mass spectrometry (ICP-MS) operating in time-resolved analysis (TRA) mode for quantifying changes in the chlorine (Cl) content of MPs under a variety of water treatment scenarios. Our results illustrated that time-resolved ICP-MS offers a potential method for sensitive and direct analysis of Cl content, including Cl mass and chlorine association (%Cl/C), of discrete particles in the MP suspension by the fast sequential measurements of signals from 35Cl1H2 and 12C1H. Our research, across various water treatment scenarios, also showed that polystyrene (PS) MPs exhibited greater reactivity to Cl disinfectant after being pre-disinfected with UV light and in mildly acidic to neutral pH environments. It is noteworthy that about half of the particles in MP suspension exposed to 10 mg Cl2/L, a typical Cl dose applied in water treatment, were chlorinated, and had a Cl content comparable to that of particles subjected to extreme conditions. Of even greater concern is the fact that our cell viability tests revealed that chlorinated MPs induced considerably higher rates of cell death in both human A549 and Caco-2 cells, and that the effects were Cl dose- and polymer type-dependent. Overall, this study demonstrates the potential of time-resolved ICP-MS as a valuable technique for quantifying the Cl content of MP particles, which is crucial to assessing the fate and transformation of MPs in our water supply and treatment systems.

PHILOSOPHICAL APPROACHES AND STRATEGIES FOR CLIMATE-RESILIENT AGRICULTURE

The development of scientific and technical mastery over nature has made the practice of agriculture, which remains the adequate condition for human subsistence, problematic. Human chemistry attacks have eventually irritated the grand chemistry of nature, leading agriculture to face unprecedented climate change. Such a situation calls for philosophical reflection and leads to considering agriculture not only as an economic activity but also as a system interconnected with nature, communities, and future generations. We have reached the following result, which emphasizes the need for a philosophy of sustainability focusing on the preservation of natural resources, the promotion of environmentally friendly agricultural practices, and agricultural policies based on ethical principles of fairness, justice, and responsibility. This philosophy, aided by education and awareness-raising among farmers, promotes ecological awareness and an understanding of the challenges of climate change, thus fostering collective resilience to climate challenges.This philosophical approach to agriculture guides towards a more sustainable, resilient, and equitable agricultural future, based on values of respect for nature, community solidarity, and collective responsibility. To achieve this result, we used the direct analysis method.

Bactericidal activity of silver nanoparticles: An analytical approach based on single cell and single particle inductively coupled plasma mass spectrometry analysis to determine silver species involved

The bactericidal activity of silver nanoparticles is supported by a large number of studies, but their action mechanisms are still a controversial issue due to the role of the silver (I) released from the nanoparticles. In this study, direct analytical methods for detection and identification of dissolved and nanoparticulate silver based on single cell and single particle inductively coupled plasma mass spectrometry (ICP-MS) and hydrodynamic chromatography ICP-MS, in combination with alkaline digestions, have been used. Detection of silver species in Escherichia coli bacteria exposed to silver allowed to confirm the different bactericidal activity associated with silver nanoparticles of different sizes. In the case of 10 nm silver nanoparticles, a combined ion-particle action would be responsible for bactericidal effect, since ionic silver was not detected in the culture medium and both dissolved and particulate silver were detected in the exposed bacteria. On the other hand, bacteria did not internalize 60 nm silver nanoparticles and their bactericidal activity was related to the ionic silver released in the culture medium.

Development and application of a comprehensive measurement equation for the direct comparator standardization method of Instrumental Neutron Activation Analysis

A comprehensive model equation for the measurement of elemental mass fractions in solid materials using the direct standardization method of Instrumental Neutron Activation Analysis was developed. The extensive modelling established for the single comparator standardization was revised and changed for the direct standardization to obtain a complete mathematical description of the measurand by physical and chemical quantities having dimensions in SI units. The model equation is presented both in case measurement and standard samples are measured in the same γ-counting position and in different γ-counting positions. The first was successfully applied for the quantitative determination of As mass fraction in a seafood matrix with a percent level relative uncertainty. The SI traceability of the result is established by a traceable standard via the measurement equation and the uncertainty budget compiled to highlight the input quantities that contribute most to the combined uncertainty.

Recent solid-phase microextraction-based analytical approaches for the profiling of biliary bile acids in pre-transplant assessments of liver grafts subjected to normothermic ex vivo liver perfusion

BackgroundLiver transplantation is the definitive treatment for end-stage liver failure, but the scarcity of donor organs remains a significant challenge. Leveraging organs from extended criteria donors (ECD) offers a potential avenue to address worldwide shortages, though these organs are more susceptible to post-reperfusion injury. This study explores the use of normothermic ex vivo liver perfusion (NEVLP) as a method for organ preservation – an approach that sustains liver metabolism and facilitates pre-transplant assessments of organ viability via bile analysis. The focal point of this study revolves on the development of analytical methods for determining the bile acid profile throughout the peritransplantation period as a potential indicator of liver function and viability. ResultsThe study optimized and validated a high-throughput analytical method to quantify selected bile acids in bile samples using a thin-film microextraction-liquid chromatography-mass spectrometry (TFME-LC-MS) platform. Furthermore, it introduced a solid-phase microextraction-microfluidic open interface-mass spectrometry (SPME-MOI-MS) method for rapid direct analysis of bile acid isobar groups. In the animal study, discernible variations in the concentrations of specific bile acids were observed between donors after circulatory death (DCD) and heart-beating donors (HBD), particularly following normothermic perfusion and reperfusion. Noteworthy fluctuations in individual bile acid concentrations were observed throughout the entire organ transplantation process, with taurocholic acid (TCA), glycocholic acid (GCA), and glycochenodeoxycholic acid (GCDCA) emerging as promising indicators of organ quality. The efficacy of the SPME-MOI-MS platform in corroborating these trends highlights its potential for real-time bile acid analysis during liver transplantation procedures. SignificanceOur findings underscore the efficacy of NEVLP in tandem with advanced bile acid analysis methods as a reliable strategy for pre-transplant assessments of organ viability, potentially increasing the use of ECD organs and reducing organ shortages. The ability to monitor bile acid profiles in real-time provides crucial insights into liver function and ischemic injury, making significant strides in improving transplant outcomes and patient survival rates.

Optimization and validation of a simple extraction method coupled with ICP-MS for the determination of essential and toxic elements in liquid dietary supplement products

This study aimed to develop and validate a fast, easy, cost-effective, and accurate method for determining Mn, Co, Ni, Cr, Cu, Fe, Zn, As, Cd, Hg, Sb, and Pb in liquid dietary supplements using an inductively coupled plasma mass spectrometer (ICP-MS). Two sample preparation methods were compared: microwave acid digestion and direct analysis after dilution. Both methods provided acceptable recovery values (87.7–111 %), with RSD values up to 6.35 %. The microwave digestion method was validated using various certified reference materials (CRMs) and a proficiency test (PT). Additionally, 34 domestic dietary supplements were analyzed using both methods, and the results were similar. Only one sample exceeded the maximum allowable limit for arsenic, which is 150 mg/kg set by the United States Pharmacopeia (USP). Two products had high Fe and Zn levels exceeding the recommended daily allowance (RDA), according to the Food and Drug Administration (FDA). This study demonstrates the effectiveness and advantages of the direct analysis method for measuring essential and toxic elements in liquid dietary supplements. This method promotes green chemistry principles and provides valuable information for ensuring consumer safety and product quality.

Research and design of a small self-heating high-temperature lithium plugging meter system

In the research of new reactors, lithium has become a research direction as a new coolant after sodium. Lithium working fluids introduce various metallic and non-metallic impurities such as oxygen, calcium, carbon, nitrogen, etc. to a greater or lesser extent during production, filling, and even operation. In addition, the processing, welding, and cleaning steps of the pipeline and equipment in the circuit during manufacturing inevitably result in residual dirt, grease, surface oxides, and moisture. These will have a certain impact on the performance of heat transfer and circuit safety through accelerated corrosion or plugging. Therefore, in high-temperature lithium circuits, the impurity concentration of lithium working fluid must be strictly controlled and purified before use. At present, the detection methods for impurity content in lithium working fluids can be divided into two categories: sampling analysis method and online measurement method. Sampling analysis is the most direct detection and analysis method, which can directly obtain the content of various impurities in lithium working fluids, and the results are relatively accurate; The online detection method can generally only detect non-metallic impurities, but it is relatively fast and simple, and is currently a commonly used measurement method on lithium working fluid devices. The plugging meter method has been studied and used as a rather convenient online detection method. This article introduces a small, self-heating, and mobile high-temperature lithium plugging meter system to meet the online detection of different points in the lithium circuit of system engineering.

[formula omitted] anti-synchronization of switching inertial neural networks with leakage delays and mixed time-varying delays

In this paper, the H∞ anti-synchronization problem of switching inertial neural networks with constant leakage delays and time-varying mixed delays is addressed. A direct analysis method based on parameterized system solutions is proposed to solve the problem we studied. The advantages of this method are that the variable substitution is not required for the system model and no Lyapunov–Krasovskii functional is constructed, which simplifies the proof process. In addition, the resulting anti-synchronization conditions consisting of some simple scalar inequalities can be easily solved by business softwares, and less computational complexity is involved. It is worth noting that the problem addressed in this paper has not been studied at present, and the limitation on the parity of activation functions in the existing literatures is removed, which reduces conservativeness. Finally, the reliability of the theoretical results is verified by numerical simulations.

A novel direct method to [formula omitted] synchronization of switching inertial neural networks with mixed time-varying delays

In this paper, the H∞ synchronization problem of switching inertial neural networks with mixed time-varying delays is discussed. A parameterized system solution-based direct analysis method combined with minimum residence time method is proposed to solve the considered problem. The advantage of this method is that no model transformation or construction of Lyapunov–Krasovskii functional is required, thus reducing the complexity of derivation process. In addition, the resulting synchronization conditions composed of some simple scalar inequalities can be easily solved via MATLAB. Finally, the reliability of the theoretical results is illustrated by numerical simulations.

THE COLLAPSE OF THE CLEAVAGE BETWEEN NATURALHISTORY AND HUMAN HISTORY

This article has endeavoured to challenge theories according to which cosmo-telluric upheavals have blurred the boundaries between natural history and human history to the point of collapsing the old humanist distinction between these two domains. We have argued that humanity is in an unprecedented situation in that it has inaugurated a new history of nature with an apocalyptic perspective, but it is excessive to believe that the conjunction between natural history and human history is a foregone conclusion for ever and ever. We have reached the conclusion that the history of nature does not have a history that is partly entangled with the history of man, but that the action of man affects fundamental processes in nature that were once considered to be able to determine human history, without being determined by it. Previously non-reciprocal action has become reciprocal, but this does not mean the end of natural history and with it the end of the great division. Nature is seriously threatening to determine human history, but this does not break down the old Nature-Culture format. To reach this result, we have used both the direct method of analysis and the historical method.

Familiarize Students with Direct MS Analysis Methods: Localization of Components in Citrus Peel by Induced Electrospray Ionization

Familiarize Students with Direct MS Analysis Methods: Localization of Components in Citrus Peel by Induced Electrospray Ionization

Advanced analysis and construction techniques for long-span spatial structures in steel engineering

This paper explores advanced analysis methods and construction techniques for long-span spatial structures in steel engineering. It delves into the principles of the Direct Analysis Method (DAM), emphasizing equilibrium, compatibility, plasticity, and stability, as well as load path and redundancy considerations. The DAM provides a robust framework for analyzing complex steel structures, ensuring stability, resilience, and efficiency. Furthermore, the paper discusses modeling techniques, including Finite Element Analysis (FEA), dynamic analysis, and nonlinear analysis, highlighting their significance in optimizing design solutions and predicting structural behavior under diverse loading conditions. Practical considerations in material selection, connection design, and construction are addressed, focusing on enhancing performance, durability, and constructability. Prefabrication and modular construction techniques are explored as effective strategies for accelerating project schedules, improving quality control, and enhancing site safety. Through a comprehensive review of literature and case studies, this paper provides valuable insights for engineers and researchers involved in the design and construction of long-span spatial structures in steel engineering.