Critical evaluation of the NIST retention index database reliability with specific examples.

The NIST gas chromatographic retention index database is widely used in gas chromatography-mass spectrometry analysis. For many compounds, the NIST database contains many entries that are presumably obtained independently of each other. We showed with specific examples that there are cases in the NIST database where several entries exist for the same compound, and all of them are equally erroneous (an error of more than 100 units). In particular, we demonstrated that all retention index values for such an important compound as imidazole for non-polar stationary phases in the NIST database are erroneous. In addition to imidazole, a similar situation is observed for four more nitrogen-containing heterocyclic compounds. For certainty, measurements were performed under several conditions, using various temperature programs, and using two specimens of columns. The structures were confirmed using nuclear magnetic resonance and mass spectrometry. It was shown with specific examples that many values are not reliable: either data were obtained using standard samples of undescribed origin without confirmation (without even using mass spectrometry) or, in some cases, standard samples were not used at all, and the retention index was obtained for a mixture component identified using a mass spectral library search. Some "independent" values are not such but are repeated publications of the same data (secondary sources), or simply several values taken from the same source. In the work, an analysis was carried out and assumptions were made about how several equally incorrect retention index values could appear in the NIST database.

ChatGPT isn't an author, but a contribution taxonomy is needed.

PURPOSE: The increasing use of AI tools, particularly large language models like ChatGPT, in academic research has raised significant questions about authorship and transparency. This commentary emphasizes the need for a standardized AI contributions taxonomy to clarify AI's role in producing and publishing research outputs, ensuring ethical standards and maintaining academic integrity. APPROACH: We propose adapting the NIST AI Use Taxonomy and incorporating categories that reflect AI's use in tasks such as hypothesis generation, data analysis, manuscript preparation, and ethical oversight. Findings: Establishing an AI contributions taxonomy for the production and publication of research output would address inconsistencies in AI disclosure, enhance transparency, and uphold accountability in research. It would help differentiate between AI-assisted and human-led tasks, providing more explicit attribution of contributions. FINDINGS: Establishing an AI contributions taxonomy for the production and publication of research output would address inconsistencies in AI disclosure, enhance transparency, and uphold accountability in research. It would help differentiate between AI-assisted and human-led tasks, providing more explicit attribution of contributions. PRACTICAL IMPLICATIONS: The proposed taxonomy would offer researchers and journals a standardized method for disclosing AI's role in academic work, promoting responsible and transparent reporting aligned with ethical guidelines from COPE and ICMJE. VALUE: A well-defined AI contributions taxonomy for the production and publication of research output would foster transparency and trust in using AI in research, ensuring that AI's role is appropriately acknowledged while preserving academic integrity.

FPGA based implementation of a perturbed Chen oscillator for secure embedded cryptosystems.

This paper introduces an enhancement to the Chen chaotic system by incorporating a constant perturbation term d to one of the state variables, aiming to improve the performance of pseudo-random number generators (PRNGs). The perturbation significantly enhances the system's chaotic properties, resulting in superior randomness and increased security. An FPGA-based realization of a perturbed Chen oscillator (PCO)-derived PRNG is presented, tailored for embedded cryptosystems and implemented on a Nexys 4 FPGA card featuring the XILINX Artix-7 XC7A100T-1CSG324C integrated chip. The Xilinx-based system generator (XSG) tool is utilized to generate a digital version of the new oscillator, minimizing resource utilization. Experimental results demonstrate that the PCO-generated data successfully passes the NIST and TestU01 test suites. Additionally, statistical tests with key sensitivity are performed, validating the suitability of the designed PRNG for cryptographic applications. This establishes the PCO as a straightforward and efficient tool for multimedia security.

Application of the CIEMAT/NIST method to 14C low-level measurements.

Radiocarbon dating of samples from benzene synthesis by low-level Liquid Scintillation Counting (LSC) method requires the availability of 14C standards in benzene, which are difficult to obtain, or the use of an absolute measurement which is out of reach for most analytical laboratories. This paper describes how the CIEMAT/NIST method can help to solve this issue and presents the measurements of low activity concentrations performed in the LRI-D using two different benzene base scintillator cocktails.

A High-Performance FPGA PRNG Based on Multiple Deep-Dynamic Transformations.

Pseudo-random number generators (PRNGs) are important cornerstones of many fields, such as statistical analysis and cryptography, and the need for PRNGs for information security (in fields such as blockchain, big data, and artificial intelligence) is becoming increasingly prominent, resulting in a steadily growing demand for high-speed, high-quality random number generators. To meet this demand, the multiple deep-dynamic transformation (MDDT) algorithm is innovatively developed. This algorithm is incorporated into the skewed tent map, endowing it with more complex dynamical properties. The improved one-dimensional discrete chaotic mapping method is effectively realized on a field-programmable gate array (FPGA), specifically the Xilinx xc7k325tffg900-2 model. The proposed pseudo-random number generator (PRNG) successfully passes all evaluations of the National Institute of Standards and Technology (NIST) SP800-22, diehard, and TestU01 test suites. Additional experimental results show that the PRNG, possessing high novelty performance, operates efficiently at a clock frequency of 150 MHz, achieving a maximum throughput of 14.4 Gbps. This performance not only surpasses that of most related studies but also makes it exceptionally suitable for embedded applications.

Changes in the Chemical Composition of Polyethylene Terephthalate under UV Radiation in Various Environmental Conditions.

Polyethylene terephthalate has been widely used in the packaging industry. Degraded PET micro(nano)plastics could pose public health concerns following release into various environments. This study focuses on PET degradation under ultraviolet radiation using the NIST SPHERE facility at the National Institute of Standards and Technology in saturated humidity (i.e., ≥95% relative humidity) and dry conditions (i.e., ≤5% relative humidity) with varying temperatures (30 °C, 40 °C, and 50 °C) for up 20 days. ATR-FTIR was used to characterize the chemical composition change of degraded PET as a function of UV exposure time. The results showed that the cleavage of the ester bond at peak 1713 cm-1 and the formation of the carboxylic acid at peak 1685 cm-1 were significantly influenced by UV radiation. Furthermore, the formation of carboxylic acid was considerably higher at saturated humidity and 50 °C conditions compared with dry conditions. The ester bond cleavage was also more pronounced in saturated humidity conditions. The novelty of this study is to provide insights into the chemical degradation of PET under environmental conditions, including UV radiation, humidity, and temperature. The results can be used to develop strategies to reduce the environmental impact of plastic pollution.

Changes in the Chemical Composition of Polyethylene Terephthalate Under UV Radiation in Various Environmental Conditions.

Polyethylene terephthalate has been widely used in the packaging industry. Degraded PET micro-nano plastics could pose public health concerns following release into various environments. This study focuses on PET degradation under ultraviolet radiation using the NIST SPHERE facility at the National Institute of Standards and Technology in saturated humidity (i.e., ≥ 95 % relative humidity) and dry conditions (i.e., ≤ 5 % relative humidity) with varying temperatures (30 °C, 40 °C, and 50 °C) for up 20 days. ATR-FTIR was used to characterize the chemical composition change of degraded PET as a function of UV exposure time. The results showed that the cleavage of the ester bond at peak 1713 cm-1 and the formation of the carboxylic acid at peak 1685 cm-1 are significantly influenced by UV radiation. Furthermore, the formation of carboxylic acid was considerably higher at saturated humidity and 50 °C conditions compared to dry conditions. The ester bond cleavage was also more pronounced in saturated humidity conditions. The novelty of this study is to provide insights into the chemical degradation of PET under environmental conditions, including UV radiation, humidity, and temperature. The results can be used to develop strategies to reduce the environmental impact of plastic pollution.

Study of smart grid cyber-security, examining architectures, communication networks, cyber-attacks, countermeasure techniques, and challenges.

Smart Grid (SG) technology utilizes advanced network communication and monitoring technologies to manage and regulate electricity generation and transport. However, this increased reliance on technology and connectivity also introduces new vulnerabilities, making SG communication networks susceptible to large-scale attacks. While previous surveys have mainly provided high-level overviews of SG architecture, our analysis goes further by presenting a comprehensive architectural diagram encompassing key SG components and communication links. This holistic view enhances understanding of potential cyber threats and enables systematic cyber risk assessment for SGs. Additionally, we propose a taxonomy of various cyberattack types based on their targets and methods, offering detailed insights into vulnerabilities. Unlike other reviews focused narrowly on protection and detection, our proposed categorization covers all five functions of the National Institute of Standards and Technology cybersecurity framework. This delivers a broad perspective to help organizations implement balanced and robust security. Consequently, we have identified critical research gaps, especially regarding response and recovery mechanisms. This underscores the need for further investigation to bolster SG cybersecurity. These research needs, among others, are highlighted as open issues in our concluding section.

Isolation and characterization of bioactive alkaloids and GC-MS based identification of volatile oil metabolites from fruits of Glycosmis pentaphylla and evaluation of their cytotoxic activity.

Glycosmis pentaphylla, a member of the Rutaceae family, has been extensively studied for its pharmacological activities, focusing mainly on the cytotoxic properties of its roots and stems. Conversely, limited researched has been done in terms of the phytochemical composition of the fruits. The objective of this study is to isolate and identify the bioactive compounds found in the fruits of G. pentaphylla and then evaluate their potential for anti-cancer activity in oral cancer CAL 27 cell lines. The extraction of bioactive compounds from fruits was done by maceration, and the isolation of alkaloids and volatile oil fractions (F1-F5) was performed by column chromatography. The alkaloids, such as 3-O-methoxyglycocitrine II, noracronycine, 1-hydroxy-3-methoxy-10-methyl-9-acridone and kokusaginine, were first isolated from the fruits of G. pentaphylla. Additionally, GC-MS analysis identified 78 metabolites. The isolated compounds and identified volatile oil fractions were explored for their anti-cancer activity by cell viability assay. Results demonstrated that isolated compounds were found inactive, while the volatile fraction F1 was found active in CAL 27 cell line. Fraction F1 impeded wound healing in CAL 27 cells by scratch assay, and significantly inhibited colony formation in colony formation assay. In cell cycle analysis, treatment with fraction F1 redistributed cells to the S and G2 phases of the cell cycle. α-elemol (2) is the major metabolite identified from the F1 fraction by GC-MS, which could be responsible for the anti-cancer activity. There is potential for future work to further isolate volatile oil metabolites and evaluate their anti-cancer activity through in-vivo techniques.

Minimum reporting standards should be expected for preclinical radiobiology irradiators and dosimetry in the published literature.

The cornerstones of science advancement are rigor in performing scientific research, reproducibility of research findings and unbiased reporting of design and results of the experiments. For radiation research, this requires rigor in describing experimental details as well as the irradiation protocols for accurate, precise and reproducible dosimetry. Most institutions conducting radiation biology research in in vitro or animal models do not have describe experimental irradiation protocols in sufficient details to allow for balanced review of their publication nor for other investigators to replicate published experiments. The need to increase and improve dosimetry standards, traceability to National Institute of Standards and Technology (NIST) standard beamlines, and to provide dosimetry harmonization within the radiation biology community has been noted for over a decade both within the United States and France. To address this requirement subject matter experts have outlined minimum reporting standards that should be included in published literature for preclinical irradiators and dosimetry.

Quantification of Unsupported Thin-Film X-ray Spectra Using Bulk Standards.

A quantification model which uses standard X-ray spectra collected from bulk materials to determine the composition and mass thickness of single-layer and multilayer unsupported thin films is presented. The multivariate model can be iteratively solved for single layers in which each element produces at least one visible characteristic X-ray line. The model can be extended to multilayer thin films in which each element is associated with only one layer. The model may sometimes be solved when an element is present in multiple layers if additional information is added in the form of independent k-ratios or model assumptions. While the algorithm is suitable for any measured k-ratios, it is particularly well suited to energy-dispersive X-ray spectrometry where the bulk standard spectra can be used to deconvolve peak interferences in the thin-film spectra. The algorithm has been implemented and made available in the Open Source application National Institute of Standards and Technology DTSA-II. We present experimental data and Monte Carlo simulations supporting the quantification model.

Activity standardisation of 32Si at IRA-METAS.

This work explores the primary activity standardisation of 32Si as part of the SINCHRON project that aims at filling the geochronological dating gap by making a new precise measurement of the half-life of this nuclide. The stability of some of the radioactive test solutions, providing 32Si as hexafluorosilicic acid (H232SiF6), was monitored over long periods, pointing to the adequate sample composition and vial type to ensure stability. These solutions were standardised using liquid scintillation counting with the triple to double coincidence ratio (TDCR) technique and the CIEMAT-NIST efficiency tracing (CNET) method. Complementary backup measurements, using 4πß-γ coincidence counting with 60Co as a tracer, were performed with both liquid and plastic scintillation for beta detection. While 60Co coincidence tracing with a liquid scintillator predicted activities in agreement with the TDCR and CNET determinations, using plastic scintillation turned out to be unfeasible as the addition of lanthanum nitrate and ammonia to fix the silicon during the drying process generated large crystals that compromised the linearity of the efficiency function.

Development of a targeted hydrophilic interaction liquid chromatography-tandem mass spectrometry based lipidomics platform applied to a coronavirus disease severity study.

The importance of lipids seen in studies of metabolism, cancer, the recent COVID-19 pandemic and other diseases has brought the field of lipidomics to the forefront of clinical research. Quantitative and comprehensive analysis is required to understand biological interactions among lipid species. However, lipidomic analysis is often challenging due to the various compositional structures, diverse physicochemical properties, and wide dynamic range of concentrations of lipids in biological systems. To study the comprehensive lipidome, a hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS)-based screening method with 1200 lipid features across 19 (sub)classes, including both nonpolar and polar lipids, has been developed. HILIC-MS/MS was selected due to its class separation property and fatty acyl chain level information. 3D models of class chromatographic retention behavior were established and evaluations of cross-class and within-class interferences were performed to avoid over-reporting these features. This targeted HILIC-MS/MS method was fully validated, with acceptable analytical parameters in terms of linearity, precision, reproducibility, and recovery. The accurate quantitation of 608 lipid species in the SRM 1950 NIST plasma was achieved using multi-internal standards per class and post-hoc correction, extending current databases by providing lipid concentrations resolved at fatty acyl chain level. The overall correlation coefficients (R2) of measured concentrations with values from literature range from 0.64 to 0.84. The applicability of the developed targeted lipidomics method was demonstrated by discovering 520 differential lipid features related to COVID-19 severity. This high coverage and targeted approach will aid in future investigations of the lipidome in various disease contexts.

Assessing the suitability of cell counting methods during different stages of a cell processing workflow using an ISO 20391-2 guided study design and analysis.

Cell counting is a fundamental measurement for determining viable cell numbers in biomanufacturing processes. The properties of different cell types and the range of intended uses for cell counts within a biomanufacturing process can lead to challenges in identifying suitable counting methods for each potential application. This is further amplified by user subjectivity in identifying the cells of interest and further identifying viable cells. Replacement of traditionally used manual counting methods with automated systems has alleviated some of these issues. However, a single cell type can exhibit different physical properties at various stages of cell processing which is further compounded by process impurities such as cell debris or magnetic beads. These factors make it challenging to develop a robust cell counting method that offers a high level of confidence in the results. Several initiatives from standards development organizations have attempted to address this critical need for standardization in cell counting. This study utilizes flow-based and image-based methods for the quantitative measurement of cell concentration and viability in the absence of a reference material, based on the tools and guidance provided by the International of Standards (ISO) and the US National Institute of Standards and Technology (NIST). Primary cells were examined at different stages of cell processing in a cell therapy workflow. Results from this study define a systematic approach that enables the identification of counting methods and parameters that are best suited for specific cell types and workflows to ensure accuracy and consistency. Cell counting is a foundational method used extensively along various steps of cell and gene therapy. The standard used in this study may be applied to other cell and gene therapy processes to enable accurate measurement of parameters required to guide critical decisions throughout the development and production process. Using a framework that confirms the suitability of the cell counting method used can minimize variability in the process and final product.

Fast gas chromatography-tandem mass spectrometry under milder electron ionization conditions for the assay of vitamin D metabolites in human serum.

The proposed research was focused on the development of a gas chromatography-tandem mass spectrometry (GC-QqQ-MS) method under milder electron ionization (EI) conditions for the assay of vitamin D metabolites in human serum. Efficiency of three different silylation agents was evaluated for the conversion of vitamin D species into trimethylsilyl (TMS) derivatives, among which N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) proved to be the most effective. Indeed, the MSTFA reagent was able to convert in TMS ether even the 25-hydroxyl vitamin D derivative that, as known, possesses steric hindrance problems. The separation of vitamin D compounds was obtained in about 11.5 min using a narrow-bore column of dimensions 30 m × 0.25 mm ID × 0.10 µm df with a poly(5% diphenyl/95% dimethyl siloxane) stationary phase. The mass spectrometry ionization of the silylated derivatives was performed under milder EI conditions (20-eV energy) that, respect to common 70-eV energy, generated scan mass spectra with higher relative and absolute intensities of high-mass diagnostic ions, along with a reduced abundance of the low-mass. The signals of the ionized compounds were acquired in multi-reaction-monitoring (MRM) mode, thus enabling the obtainment of highly-sensitive and selective quantitative data. The developed method was validated in term of linearity, accuracy, limits of detection (LoD) and quantification (LoQ). In detail, regression coefficients of the calibration curves were between 0.9959 and 0.9999; LoDs ranged from 0.06 ng mL-1 to 0.73 ng mL-1 and LoQs from 0.16 ng mL-1 to 2.45 ng mL-1. With respect to accuracy, the serum SRM 972a certified reference material (Vitamin D metabolites in frozen human serum) (Levels 1-4) was analyzed.

Laser Ablation Inductively Coupled Plasma Mass Spectrometry Imaging of Plant Materials.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a sensitive technique which enables fast, spatially resolved analysis of elements at trace concentration levels in a range of solid sample types, including plant materials. Within this chapter, we describe how to prepare leaf material and seeds for elemental distribution imaging, how to embed material in gelatin and epoxy resin, how to produce matrix-matched reference materials, and how to optimize laser ablation methods.

Enhanced post-quantum key escrow system for supervised data conflict of interest based on consortium blockchain.

Consortium blockchains offer privacy for members while allowing supervision peers access to on-chain data under certain circumstances. However, current key escrow schemes rely on vulnerable traditional asymmetric encryption/decryption algorithms. To address this issue, we have designed and implemented an enhanced post-quantum key escrow system for consortium blockchains. Our system integrates NIST post-quantum public-key encryption/KEM algorithms and various post-quantum cryptographic tools to provide a fine-grained, single-point-of-dishonest-resistant, collusion-proof and privacy-preserving solution. We also offer chaincodes, related APIs, and invoking command lines for development. Finally, we perform detailed security analysis and performance evaluation, including the consumed time of chaincode execution and the needed on-chain storage space, and we also highlight the security and performance of related post-quantum KEM algorithms on consortium blockchain.

Quantification of 25-hydroxyvitamin D2 and D3 in Mitra® devices with volumetric absorptive microsampling technology (VAMS®) by UHPLC-HRMS for regular vitamin D status monitoring.

The numbers of vitamin D inadequacies has reportedly increased in the general population, especially in the Northern hemisphere. However, routine measurement of 25(OH) vitamin D is usually associated with a substantial effort due to the requirement of a venous blood sample taken by medical professionals. Thus, the objective of this work is to develop and validate an easy and minimal-invasive method, using a microsampling technique for autonomous blood collections by medically untrained individuals. The assay enables a simplified monitoring of the vitamin D-status in both, risk group and normal population throughout the year. For this purpose, a simple methanol extraction without derivatization combined with a UHPLC-HRMS method was developed to quantify 25(OH)D2 and 25(OH)D3 in capillary blood. For sample collection, a 20 µl Mitra® device with VAMS® technology is used. By employing the six-fold deuterium-labelled 25(OH)D3 as internal standard, the validated assay provides accurate (<10%) and precise (<11%) results. With a LOQ of 5 ng/ml, the approach also proved sensitive enough to adequately identify potential vitamin D deficiencies (< 12 ng/ml), and proof-of-concept analyses of authentic VAMS® samples (n = 20) yielded test results in the expected blood concentration range. Implementing VAMS® sampling for vitamin D-status monitoring enables a higher frequency due to a simplified, straightforward, and time-effective sample collection. VAMS® assures accurate sample volumes because of its absorptive capacities and, thus, area bias and homogeneity issues associated with conventional DBS are avoided. Regular monitoring of 25(OH)D status throughout the year supports people in high-risk groups for vitamin D-deficiency by early identifying inadequacies and, thus, preventing adverse health consequences.

T1 relaxation time of ISMRM/NIST T1 phantom spheres at 7 T.

T1 relaxation times of the 14 T1 phantom spheres that make up the standard International Society for Magnetic Resonance in Medicine (ISMRM)/National Institute of Standards and Technology (NIST) system phantom are reported at 7 T. T1 values of six of the 14 T1 spheres at 7 T (with T1 > 270 ms) have been reported previously, but, to the best of our knowledge, not all of the T1s of the 14 T1 spheres at 7 T have been reported before. Given the increasing number of 7-T MRI systems in clinical settings and the increasing need for T1 phantoms that cover a wide range of T1 relaxation times to evaluate rapid T1 mapping techniques at 7 T, it is of high interest to obtain accurate T1 values for all the ISMRM/NIST T1 spheres at 7 T. In this work, T1 relaxation time was measured on a 7-T MRI scanner using an inversion-recovery spin-echo pulse sequence and derived by curve fitting to a signal equation that exhibits insensitivity to B 1 + inhomogeneity. Day-to-day reproducibility was within 0.4% and differences between two different RF coils within 1.5%. T1s of a subset of the 14 spheres were also measured by NMR at 7 T for comparison, and the T1 results were consistent between the MRI and NMR measurements. T1 measurements performed at 3 T on the same 14 spheres using the same sequence and fitting method yielded good agreement (mean percentage difference of -0.4%) with the reference T1 values available from the NIST, reflecting the accuracy of the reported technique despite being without the standard phantom housing. We found that the T1 values of all 14 NiCl2 spheres are consistently lower at 7 T than at 3 T. Although our results were well reproduced, this study represents initial work to quantify the 7-T T1 values of all 14 NIST T1 spheres outside of the standard housing and does not warrant reproducibility of the ISMRM/NIST system phantom as a whole. A future study to assess the T1 values of a version of the ISMRM/NIST system phantom that fits inside typical commercial coils at 7 T will be very helpful. Nonetheless, the details on our acquisition and curve-fitting methods reported here allow the T1 measurements to be reproduced elsewhere. The T1 values of all 14 spheres reported here will be valuable for the development of quantitative MR fingerprinting and rapid T1 mapping for a large variety of research projects, not only in neuroimaging but also in body MRI, musculoskeletal MRI, and gadolinium contrast-enhanced MRI, each of which is concerned with much shortened T1.