bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein—Ion Charge-State Distributions in Electrospray Ionization Mass Spectrometry: Distinguishing Conformational Contributions from Masking Effects
Authors: Gumerov Dmitry R. , Dobo Andras , Kaltashov Igor A.
Published: July 2002

Electrospray ionization mass spectrometry (ESI-MS) is often used to monitor protein conformational dynamics in solution, for example acid unfolding, by following the changes in positive-ion charge-state distributions in response to changes of ambient conditions, for example solution pH. Deconvolution of these charge-state distributions often reveals the presence of multiple protein conformers coexisting in solution in equilibrium. The ion signal corresponding to each conformer depends on its size (which determines the average charge state of the protein ions) and heterogeneity (which determines the spread of the ion signal). In the present work, we seek to explore how the ion signal of individual protein conformers can be influenced by other factors not related to protein shape, with particular attention being paid to contributions from solution acid-base chemistry. The composition of the buffer was found to exert a significant influence on the ion signal by inducing apparent charge reduction of the protein ions. This effect was ascribed to protein-base (anion) complex formation in solution followed by dissociation of the neutral conjugated acid from the complex in the gas-phase. The resulting shift in the charge-state distribution occurs in the pH range from p Ka to approximately (p Ka −1.5) and is induced by the elevated concentration of the anion in solution. On the other hand, intrinsic charges on the protein in solution have been shown to have no effect on the appearance of the charge-state distributions, lending further credibility to the notion that protein shape is the only structural determinant of the ion signal in ESI-MS.
Fast-Atom Bombardment Mass Spectrometry in Heterogeneous Atmospheric Chemistry
Authors: Pronchev G.B. , Korobeinikova I.A. , Yermakov A.N.
Published: July 2002

The application of fast-atom bombardment (FAB) mass spectrometry to solving the problems of heterogeneous atmospheric chemistry is briefly reviewed. The method is useful in studying the state of surfaces and molecules adsorbed thereon and looks appropriate in investigations of the dynamics and mechanisms of chemical reactions occurring both on a surface and in a volume of moving particulate matter suspended in a gas. It was shown that composition of atmospheric aerosols and components dissolved in atmospheric water (clouds, fogs, mists etc.) can be determined by the FAB technique. The given method, as was found in our investigations, allows the discrimination of ferrous and ferric ions. Detection limits for concentrations of H2SO4 and Fe(II / III) ions as essential components of atmospheric water determined in model experiments are established at the level of 10−6 M.
Stereospecific Ion—molecule Reactions in the Trans-Decahydro-4-Hydroxyquinoline Series upon Chemical Ionization
Authors: Zaikin Vladimir G. , Borisov Roman S.
Published: July 2002

A series of C-2- and C-4-stereoisomeric 2-methyl-, 1,2-dimethyl- and 1-butyl-2-methyl- trans-decahydro-4-hydroxyquinolines, having a conformationally stable bicyclic system and an additional 4-substituent (chosen from ethyl, ethynyl, ethenyl, butyl and vinylethynyl), was investigated by isobutane and methane chemical ionisation (CI). It was shown that, independently of the nature of the reagent gas, the spectra of stereoisomers at C-4 differed in the intensity ratios of the [MH]+ and [MH–H2O]+ ion peaks; the latter peaks are always less intense in the case of compounds containing an axial 4-OH group. The same regularity was observed for isobutane CI followed by collision-induced dissociation and for methane CI, although the intensity ratios differ. “Approach control” was suggested to explain the observed stereospecificity of the protonation of the alcohols at the hydroxyl group. The results obtained provide a useful tool for the determination of the configuration of hydroxyl-carrying centers in other trans-decahydro-4-hydroxyquinolines and related compounds.
A Study of Ion—molecule Reactions in the Xe+ + Acetone System by Flow Technique Mass Spectrometry
Authors: Vinogradov P.S. , Misharin A.S.
Published: July 2002

Flow reactor technique mass spectrometry was used to study the reaction of Xe+ ions with acetone and the subsequent transformation of the product ions at a buffer gas (He) pressure of 1.1 Torr. A kinetic scheme describing the evolution of the ionic composition of the most abundant ionic constituents (up to the fourth generation) has been determined. The values of rate constants and branching ratios of the key reactions involved in the scheme have been evaluated from experimental kinetic dependences. The main channel of the Xe+ + acetone reaction (which occurs practically at each collision) is the production of the CH3CO+ fragment as the exothermicity of the charge transfer is higher than the dissociation threshold of the ground state acetone cation. The formation of a 2.5% fraction of the molecular ion via a parallel channel indicates that the production of an electronically-excited, long-lived state of the acetone cation takes place. The competition of association and particle-rearrangement processes in the reactions of the CH3CO+ ion and its CH3CO+(CH3)2CO cluster with acetone was also studied. It was found that channels in which a rearrangement of particles takes place (the production of protonated acetone for CH3CO+ and the protonated acetone dimer for CH3CO+(CH3)2CO) are slower than the association process at 1.1 Torr. Total effective rate constants (involving all the channels) for these ions are approximately several 10−10 cm3 s−1 units and the rate constant for the cluster ion is about 40% smaller. The production of slowly reacting C3H6O+ ions with an increase of acetone concentration was observed. Their structure may be ascribed to the enolic acetone cation (CH2COHCH3+). The only pathway for the loss of the ion in an exoergic reaction with acetone is the association process. The product of the process, i.e. the non-protonated ionic dimer of acetone, was also observed in the mass spectra.
Origin of Clusters: IV. Low Temperature Fast-Atom Bombardment Cluster Patterns Point to the Possible Existence of NaCl Crystalline Hydrates Incorporating Heavy Water
Authors: Kosevich Marina V. , Boryak Oleg A. , Shelkovsky Vadim S.
Published: July 2002

Low temperature fast-atom bombardment study of frozen D2O–NaCl solutions gave results similar to those obtained earlier for the H2O–NaCl system. Thus, sets of clusters (D2O) n•D+, (D2O) n•Na+, (D2O) n•NaCl•Na+, (NaCl) m•Na+ with a characteristic distribution depending on the composition of the sample and phase transitions on its thawing were recorded. A typical cluster pattern, attributed in the case of the H2O–NaCl system to a phase of a crystalline hydrate NaCl•2H2O, was observed for the D2O–NaCl system as well. At the same time, recently available reference data on the solubility of NaCl do not contain a specification for the formation of a crystalline hydrate on cooling of NaCl solution in D2O. Considering the present mass spectrometry data, the possibility of incorporation of heavy water into NaCl crystalline hydrates is discussed.
Determination of Isotope-Enrichment Ratios in Proteins by High-Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
Authors: Demirev Plamen A. , Fenselau Catherine
Published: July 2002

Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been applied for determining the 13C and 15N stable isotope content of a 10 kDa protein molecule. Purified samples of modified human ubiquitin, expressed in E. coli grown in a 13C and 13N isotope-enriched medium, are electrosprayed in a 4.7 T FT-ICR instrument. The intensity profiles of the isotopically-resolved envelope of the molecular ions in different charge states are averaged. The experimental data are then compared to theoretically-generated isotopic profiles for the same molecule at varying ratios of 12C: 13C and 14N: 15N isotope enrichment. The isotope-enrichment ratios giving the best overlap between simulated and experimental data correspond to estimates of incorporation from the 13C and 15N isotopes present in the microorganism growth medium.
High Performance Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry at Low Magnetic Field
Authors: Gorshkov Michael V. , Udseth Harold R. , Anderson Gordon A. , Smith Richard D.
Published: July 2002

A comprehensive characterization of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer utilizing a 1 tesla magnet with an electrospray ionization (ESI) source is presented. A resolution of up to 10,000,000 and a ppb-level mass accuracy has been achieved for atomic ions and light molecules produced with electron ionization. It has also been demonstrated that a resolution of up to 1,000,000 can be achieved for signals from biomolecule ions obtained with an ESI source, with the highest molecular weight for which the 13C isotopic pattern was completely resolved being that of ubiquitin (8565 Da). Several features of FT-ICR mass spectrometry at low magnetic field are discussed and approaches to overcome the low-field constraints are presented.
Hydrogen Atom Loss in Electron-Capture Dissociation: A Fourier Transform-Ion Cyclotron Resonance Study with Single Isotopomeric Ubiquitin Ions
Authors: Breuker Kathrin , Oh HanBin , Cerda Blas A. , Horn David M. , McLafferty Fred W.
Published: July 2002

In electron-capture dissociation (ECD), a multiply-protonated protein ion, trapped in a Fourier transform-ion cyclotron resonance (FT-ICR) cell, captures a low-energy electron at a protonated site. In a major reaction pathway, the resulting hydrogen atom attacks a backbone carbonyl oxygen to form a hypervalent species that immediately dissociates into a complementary c, z• ion pair. For larger proteins, the reduced odd-electron ion (M + nH)( n −1)+• is a major product, as shown here using isotopically isolated precursors. In addition, a hydrogen atom can be lost without further reaction, yielding the [M + ( n −1)H]( n −1)+ even-electron ions. The large effect of charge state on the yield of these ions suggests that the 9+ to 11+ charge states have novel charge-solvated secondary structures.
A Theoretical Investigation of the Kinetic Energy of Ions Trapped in a Radio-Frequency Hexapole Ion Trap
Authors: McDonnell Liam A. , Giannakopulos Anastassios E. , Derrick Peter J. , Tsybin Youri O. , Håkansson Per
Published: July 2002

The kinetic energy dependence of ions trapped in a radio-frequency (RF) hexapole ion trap has been calculated as a function of space charge, mean free path, mass, RF potential and charge. The average kinetic energy of the ions was found to increase with increasing space charge, mean free path and the ion charge state. For a trapped ion in a given coulombic field, the mass of the ion and the amplitude of the applied RF potential did not affect the average kinetic energy. The consequences for multipole-storage-assisted dissociation (MSAD), in which ions are accumulated for prolonged periods of time in the multipole ion trap of an electrospray ion source, are discussed. As a result of radial stratification inside the ion trap, MSAD can lead to the preferential excitation of ions with larger m/z values. Such discrimination would have negative consequences for the detection of labile non-covalent adducts, which are normally detected at higher m/z values than their constituent species.
Letter: Hydroxide and Oxygen Atom Attachment to Dichlorophthalic Anhydride in Negative-Ion Chemical Ionization with Collisionally-Activated Dissociation in an External-Source Ion Trap Mass Spectrometer
Authors: Wu Hui-Fen , Chen Chien-Hung
Published: July 2002

This study reports the investigation of some unusual adduct ions of hydroxide and oxygen atoms in both negative-ion chemical ionization (NCI) and collisionally-activated dissociation (CAD) processes in an external-source ion trap mass spectrometer. The [M + OH]− and [M + OH – Cl]− adduct ions in the NCI spectrum of 4,5-dichlorophthalic anhydride are attributed to an ion/molecule reaction due to the presence of trace amounts of water. The formation of the unusual [M + O – Cl]− ions during CAD of the M− ions from 3,6-and 4,5-dichlorophthalic anhydride isomers is attributed to reactive collisions of the fragment ions with residual oxygen.
Wavelength- and Time-Resolved Luminescence Spectroscopy for Investigation of the Matrix-Assisted Laser Desorption Process
Authors: Zechmann Carsten , Muskat Tassilo , Grotemeyer Jürgen
Published: July 2002

This work deals with investigations of fluorescence phenomena during interaction of ultraviolet laser radiation with four substances (2,5-dihydroxybenzoic acid, 3-hydroxypicolinic acid, dithranol and ferulic acid) commonly used as matrices in matrix-assisted laser desorption/ionization (MALDI). Wavelength-resolved fluorescence measurements allowed classification of UV-MALDI matrices on the basis of their Stokes shift. Matrices showing a high Stokes shift dissipated high amounts of laser energy by means of intra- and intermolecular energy transfer processes, hence contributing less to the ionization of analyte compounds. Conversely, matrix substances with a low Stokes shift retained more of the original photonic energy which may then be available for ionization within the matrix or after desorption of molecular species. Therefore matrix compounds can be designated as “hard” (high ionization energy) in the case of small Stokes shifts or “soft” (low ionization energy) in the case of high Stokes shifts. Time-resolved measurements showed fluorescence lifetimes below 5 ns for all four substances.
Ion Motion Stability Diagram for Distorted Square Waveform Trapping Voltage
Authors: Sudakov M. , Nikolaev E.
Published: July 2002

Ion motion in a periodic radio frequency (RF) quadrupole electric field is analysed theoretically by the matrix method and direct trajectory calculation. General properties of the ion motion: stability condition, oscillation spectrum and secular frequency are derived analytically from the elements of the transformation matrix. Stability diagrams for ion motion in the Paul ion trap are presented for rectangular waveforms with different duty cycles (duration of pulse over period). Calculation of the secular frequencies of the ion motion in the ion trap is performed for the first time. The relation of radial and axial secular frequencies along the RF scan line was found to be practically identical in both the square waveform and harmonic voltage cases. Pulse shape distortions, due to resistive-inductive-capacitive filtering in real devices, are considered. Stability diagrams of ion motion in the ion trap with distorted voltage waveforms are calculated. Distortion of the waveform is shown to introduce minor changes in the diagram shape with respect to the diagram for an ideal square wave. Within the first stable region, distortion of the waveform does not lead to any auxiliary parametric resonances of the ion motion. Ion trapping with a pure random pulsed voltage is investigated by means of direct trajectory simulations. It is shown that, in this case, the ion motion can be conditionally stable for a considerable length of time.
Quadrupole Mass Filter Transmission in Island a of the First Stability Region with Quadrupolar Excitation
Authors: Glebova Tatyana , Konenkov N.V.
Published: July 2002

With quadrupolar excitation of ions by a small auxiliary RF field, the first stability region of the quadrupole mass filter splits into islands of stability. This study is of the first upper island, “A”. We calculate the location of this island for different values of the excitation parameter, q‘. Ion trajectory calculations are used to study the influence of the input fringing fields and the separation time. The Runge-Kutta–Nustrom–Dormand-Prince (RK–N–DP) method of order 6(7) is used for integration of the equations of ion motion. It is found that a weak auxiliary RF signal improves the peak shape for quadrupole mass filters that have weak field distortions.
Creeping Discharge Mass Spectrometry: A New Method for Elemental Analysis of Dielectrics
Authors: Gall L.N. , Kouzmin A.G.
Published: July 2002

The creeping discharge (CD), a special kind of surface discharge, is proposed as a method of ionization in mass spectrometry for elemental analysis of dielectrics. Characteristic features of creeping discharge ionization mass spectra of dielectric samples were studied. An yttrium oxide standard sample and dielectrics of high electric strength were successfully analyzed. The results of analysis of the ion charge state in creeping discharge are presented. A theoretical model of creeping discharge ionization is offered.
Can Laser-Ionisation Time-of-Flight Mass Spectrometry Be a Promising Alternative to Laser Ablation/Inductively-Coupled Plasma Mass Spectrometry and Glow Discharge Mass Spectrometry for the Elemental Analysis of Solids?
Authors: Sysoev Alexander A. , Sysoev Alexey A.
Published: July 2002

At the beginning of the age of laser-ionisation mass spectrometry (LIMS) increasing numbers of publications were observed. However, later the method began to run into obstacles associated with poor reproducibility of analysis and large variations in elemental sensitivities so that the wide interest of the scientific community in the method faded away. However, the results described here show that the current knowledge of laser plasma processes, together with modern technical solutions to ion separation and quantification with time-of-flight (ToF) mass spectrometry, allow one to overcome the above-mentioned obstacles in LIMS. Thus, the performance in direct-sampling solid analysis demonstrated by the LAMAS-10M instrument is similar to that typically obtained by laser ablation/inductively-coupled plasma mass spectrometry (LA-ICP-MS) and glow-discharge mass spectrometry (GD-MS) methods. At the same time, there are additional advantages, including compactness of the instrument, absence of the need for expensive consumables and freedom from mass line interferences. Direct-sampling elemental LIMS is discussed as a promising alternative to LA-ICP-MS and GD-MS. Existing and prospective approaches to designing direct-sampling laser-ionisation mass spectrometers are theoretically justified. Factors affecting the main performance criteria, such as reproducibility, correctness, variations of relative sensitivity factors, linear dynamic range and resolution are considered. The demonstrated reproducibility, resolution, low-ppb limit of detection and one order-of-magnitude variation in elemental sensitivity are not the limit for direct-sampling laser-ionisation mass spectrometry of solid samples. Ways of improving LI-ToF-MS instrumental performance are discussed and theoretically justified.
Mass Spectrometric Studies of Physical, Thermochemical and Reactive Properties of Xenon Fluorides, Xenon Oxides and Xenon Oxyfluorides
Authors: Zelenov Vladislav V. , Aparina Elena V. , Loboda Alexander V. , Kukui Alexander S. , Dodonov Alexander F. , Kashtanov Sergei A. , Aleinikov Nicolai N.
Published: July 2002

Using a reactor with a flowing diffusion cloud coupled to a high-resolution, low-energy electron-impact ionization mass spectrometer, mechanistic, kinetic and thermochemical characteristics of gas-phase reactions with the participation of charged and neutral xenon oxides, xenon fluorides and xenon oxyfluorides have been investigated. Ionization energies for XeF, XeF2, XeF4, XeO3, XeO4, XeOF4 molecules and appearance energies for the ions formed from these molecules were obtained. Based on experimental and reference data, the enthalpies of XeO3 and XeOF4 formation were refined and a number of binding energies in the parent and fragment ions were calculated. For electron-impact ionization, the ionization cross-sections for Xe, XeF2, XeF4 and XeOF4 proved to correlate with a semi-empirical principle of full ionization. Based on the temperature dependencies of saturated vapor pressures for XeO4, XeOF4 and XeO2F2, their enthalpies of evaporation, sublimation and melting were determined. The mechanisms of gas-phase reactions between H atoms and neutral XeF2, XeF4, XeF6, XeO4 and XeOF4 were studied.
Electron Impact Mass Spectra Data Processing for Evaluation of Gas-Phase Reactivity of Cymantrene (Tricarbonyl η5-Cyclopentadienylmanganese) Derivatives
Authors: Nekrasov Yu.S. , Sukharev Yu.N. , Tepfer E.E. , Yakushin S.O.
Published: July 2002

The experimental and information indices of cymantrene derivatives were calculated from their electron impact mass spectra. Correlations were found between some of the indices and the structural and bonding properties of the molecules.
Unimolecular Decomposition in Ion Cyclotron Resonance Traps: Kinetic Energy Release and Microsecond-Scale Kinetics
Authors: Rakov V. Sergey , Futrell Jean H.
Published: July 2002

A method of recovering information about the kinetics and dynamics of gas-phase ion-molecule reactions which occur on a microsecond time scale inside a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) cell is presented. In FT-ICR experiments, the typical time-scale of the ion detection is of the order of milliseconds to seconds and the microsecond-scale reactions usually run to completion before the detection takes place. However, axial oscillation inside the ICR cell can be made very fast and the efficiency of the dynamic voltage trapping depends on the axial position of the ions. We present a theoretical model which relates experimental ion abundance to the life-times and kinetic energy releases, illustrating it with an example of fast-decomposing chromium hexacarbonyl molecular cation activated by collision with a fluorinated self-assembled monolayer surface in a 7-Tesla FT-ICR cell. General formalism, quantitative limitations and application of this method to measure lifetimes and the kinetic energy releases of less-studied ionic systems are addressed in detail.
Infrared Matrix-Assisted Laser Desorption/Ionization Quadrupole Ion Trap Mass Spectrometry
Authors: Lippa Timothy , Taranenko Nelli I. , Prasad Coorg R. , Doroshenko Vladimir M.
Published: July 2002

Performance characteristics of an infrared (IR) matrix-assisted laser desorption/ionization (MALDI) quadrupole ion trap (QIT) mass spectrometer are presented. Both an IR laser and an ultraviolet (UV) laser have been coupled to the MALDI ion source, allowing for a comparative study of the spectra obtained for the same analyte molecules taken at these two wavelengths. The mass range of the QIT instrument was extended by operating it at a frequency as low as 200 kHz. The results presented for small and medium-size peptides demonstrated a lesser degree of analyte ion fragmentation in the case of the IR-MALDI source compared with that obtained using the UV-MALDI source. Due to the fragmentation phenomenon, the mass resolution for cytochrome C ions(MW12384 Da) was an order of a magnitude higher in the case of IR-MALDI compared with the use of UV-MALDI. This phenomenon has been shown to effect the calibration of the trap instrument for higher masses.
How do social norms influence the sexual and reproductive health of very young adolescents in sub-Saharan Africa? A scoping review protocol
Authors: Ahmed Fardawsa , Nyamwanza Owen , Ladur Alice N. , Dambi Jermaine , Cowan Frances , Mavhu Webster
Published: February 2025

Introduction Introduction Very young adolescents (VYAs, aged 10–14 years) in sub-Saharan Africa (SSA) have the worst sexual and reproductive health (SRH) outcomes of this age group worldwide due to structural, behavioural, socioeconomic and other factors. Social and gender norms have important consequences for the SRH and wellbeing of VYAs both now and over their life course. SRH programming often focuses on older adolescents (aged 15–19 years), overlooking younger ones. This scoping review sets out to explore how social and gender norms influence VYAs’ SRH in SSA, in addition to exploring interventions that have been effective, to inform a context-specific intervention. Methods We will employ the methodology developed by Arksey and O'Malley to review the available literature. We will search online databases (PubMed/MEDLINE, CINHAL, EMBASE, PsycINFO, Cochrane Library, and African Index Medicus) for original studies published between 1 January 2000 and 31 December 2024. Further, we will perform a manual search to include relevant grey literature. The steps in the review are: 1) defining the research question, 2) identifying relevant studies, 3) selecting studies, 4) charting the data, and 5) collating, summarising, and reporting the results. Results Results We will report findings in accordance with the guidance provided in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement. We will analyse and summarise data about study characteristics using descriptive statistics. We will use thematic analysis to analyse and summarise key themes and issues. We will triangulate quantitative and qualitative findings. Discussion The review will map the breadth of studies focusing on social and gender norms, and SRH among VYAs, in addition to exploring interventions that have been effective. Findings will help us and others develop context-specific, bespoke interventions.
EFFICIENT RIBOSOMAL RNA DEPLETION FROM DROSOPHILA TOTAL RNA FOR NEXT-GENERATION SEQUENCING APPLICATIONS
Authors: Koppaka Omkar , Tandon Shweta , Chodankar Ankita , Pandit Awadhesh , Bakthavachalu Baskar
Published: February 2025

We developed a cost-effective enzyme-based rRNA-depletion method tailored for Drosophila melanogaster, addressing the limitations of existing commercial kits and the lack of peer-reviewed alternatives. Our method employs single-stranded DNA probes complementary to Drosophila rRNA, forming DNA-RNA hybrids. These hybrids are then degraded using the RNase H enzyme, effectively removing rRNA and enriching all non-ribosomal RNAs, including mRNA, lncRNA and small RNA. When compared to a commercial rRNA removal kit, our approach demonstrated superior rRNA removal efficiency and mapping percentage, confirming its effectiveness. Additionally, our method successfully enriched the non-coding transcriptome, making it a valuable tool for studying ncRNA in Drosophila. The probe sequences and rRNA-depletion protocol are made freely available, offering a reliable alternative for rRNA-depletion experiments.
Znajomość języka polskiego u Włochów zdających egzaminy certyfikatowe w latach 2004–2015: (ze szczególnym uwzględnieniem sprawności pisania)
Authors: Marzec Urszula
Published: February 2025

Monografia Znajomość języka polskiego u Włochów zdających egzaminy certyfikatowe w latach 2004–2015 stanowi teoretyczno-badawcze studium z zakresu glottodydaktyki polonistycznej. Przedmiotem podjętych przez autorkę rozważań są kompetencje językowe Włochów, którzy przystąpili do egzaminu certyfikatowego z języka polskiego jako obcego w latach 2004–2015. W rozprawie został po raz pierwszy opisany w sposób szczegółowy, a więc z uwzględnieniem wyników uzyskanych we wszystkich częściach egzaminu, udział grupy jednorodnej pod względem języka funkcjonalnie pierwszego w procesie certyfikacji JPJO. Publikacja wypełnia lukę poznawczą w obszarze badań nad jakością polszczyzny cudzoziemców. Jest pierwszym tak dogłębnym i obszernym opracowaniem naukowym dotyczącym specyfiki nabywania języka polskiego przez osoby włoskojęzyczne. Poszerza wiedzę na temat trudnych dla italofonów kwestii w polskim systemie językowym oraz deficytów w rozwoju sprawności testowanych podczas egzaminów certyfikatowych (zwłaszcza pisania po polsku). Czytelnik znajdzie tutakże spis zagadnień, którym autorzy programów nauczania, podręczników i pomocy dydaktycznych dla Włochów powinni poświęcić szczególną uwagę.
Measurement of Ageism in Mexican University Students: Psychometric Properties of the Negative Stereotypes Questionnaire towards Old Age
Authors: Blanco Ornelas José René , Aguirre Susana I. , Diaz Leal Ana Citlalli , Jurado-García Perla Jannet
Published: February 2025

Introduction: the present study aims to investigate the psychometric results proposed by Mena, Sánchez-Palacios (1) for the questionnaire on negative stereotypes towards old age (CENVE). Materials and methods: the total sample comprised 1480 participants; all of them students of the degree of Physical Education and Human Motricity offered at the Autonomous University of Chihuahua, with a mean age of 2.53 years (SD=1.84) for women and 20.90 (SD = 2.05) for men. Psychometric analysis showed that a one-factorial structure was viable and adequate. Results: the factorial structure of the questionnaire was analyzed with confirmatory factor analysis. The structure of a single factor (stereotypes towards old age), attending to substantive and statistic criteria, showed adequate indicators of adjustment of reliability and validity. Future research should replicate these findings in larger samples.
The impact of integrated subtitles on viewers’ comprehension, emotions, and reception: A mixed-methods study
Authors: Wu Zhiwei
Published: February 2025

This paper reports on a mixed-methods study that examined the impact of integrated subtitles on viewers’ comprehension, emotions, and reception. Two groups of Chinese viewers were randomly assigned to a control group (n = 31) and an experimental group (n = 31). The control group watched French videos with standard Chinese subtitles positioned at the bottom of the screen, while the experimental group watched the same videos with integrated subtitles placed closer to the speakers as part of the mise-en-scène. Major findings included the following: (a) the two groups did not differ in their comprehension of film content; (b) integrated subtitles modestly contributed to the participants’ emotional intensity with regard to the protagonists; (c) integrated subtitles led to higher self-reported cognitive load; (d) integrated subtitles were perceived less favourably compared to the standard subtitles; and (e) presentation-, product-, and person-related factors were identified to shape the participants’ perception of integrated subtitles. Building on these findings, the paper discusses some practical suggestions for promoting integrated subtitles and personalised subtitles.
Defining and Institutionalizing Proactive Advising: Insights from a National Survey
Authors: Rust Matthew M. , Willey Ann Elizabeth
Published: February 2025

Calls to adopt proactive advising as a student success strategy are common, but evidence on what this entails is scarce. We present results from a national survey on the conceptualization and institutionalization of proactive advising at four-year U.S. colleges and universities. Examining differing views among advisors and administrators, we identify advising practices, implementation strategies, and technologies deemed absent but necessary to institutionalize proactive advising. Through multilevel modeling, we estimate that absent-but-needed implementation strategies have the greatest effect on respondent impression of institutionalization, and that the effects of absent-but-needed technologies depend on respondent role. Summarizing findings from regression and content analyses, we propose a comprehensive definition of proactive advising and recommend successful institutionalization through coordinated rather than decentralized efforts.
An optically transparent transmissive orbital angular momentum (OAM) metasurface with high transmittance and broadband characteristics
Authors: wang gang , Xu Guanghui , Cai Yong , Dai Yuying , Ma Yue , Ren Xingang , Wang Hui , Xiaohu Zhao , Wu Xianliang
Published: February 2025

This work proposes a high-performance broadband Orbital Angular Momentum (OAM) beam-generating metasurface based on optically transparent media. A broadband polarization-converting transmissive metasurface operating in the 18-24 GHz range has been realized through the collaborative design of dual C-shaped split-ring resonator structures and bidirectional lattice-patterned surface networks. The array structure demonstrates typical helical phase distribution features in the Ku-band, with experimental verification showing over 92% consistency between higher-order mode (l=2) wavefront structures and simulations. Innovatively employing a composite structure of quartz glass substrate and patterned indium tin oxide (ITO) films, the design achieves compatible optimization of 85% visible-light transmittance and microwave broadband performance. This approach breaks through the mutually exclusive limitations of traditional metasurfaces' optical/electromagnetic properties, providing a highly integrated solution for transparent antenna randoms in satellite communication systems and multi-mode beam multiplexing applications.
Antigen-specific T cell responses following single and co-administration of tick-borne encephalitis, Japanese encephalitis, and yellow fever virus vaccines: Results from an open-label, non-randomized clinical trial-cohort
Authors: Wullimann David , Sandberg John Tyler , Akber Mira , Löfling Marie , Gredmark-Russ Sara , Michaëlsson Jakob , Buggert Marcus , Blom Kim , Ljunggren Hans-Gustaf
Published: February 2025

Background

Flavivirus infections pose a significant global health burden, highlighting the need for safe and effective vaccination strategies. Co-administration of different vaccines, including licensed flavivirus vaccines, is commonly practiced providing protection against multiple pathogens while also saving time and reducing visits to healthcare units. However, how co-administration of different flavivirus vaccines de facto affects immunogenicity, particularly with respect to T cell responses, is only partially understood.

Methods and findings

Antigen-specific T cell responses were assessed in study participants enrolled in a previously conducted open-label, non-randomized clinical trial. In the trial, vaccines against tick-borne encephalitis virus (TBEV), Japanese encephalitis virus (JEV), or yellow fever virus (YFV) were administered either individually or concomitantly in different combinations in healthy study participants. Peripheral blood samples were collected before vaccination and at multiple time points afterward. To analyze antigen-specific CD4+ and CD8+ T cell responses, PBMCs were stimulated with overlapping peptide pools from TBEV, JEV, YFV, and Zika virus (ZIKV) envelope (E), capsid (C), and non-structural protein 5 (NS5) viral antigens. A flow cytometry-based activation-induced marker (AIM) assay was used to quantify antigen-specific T cell responses. The results revealed remarkably similar frequencies of CD4+ and CD8+ T cell responses, regardless of whether vaccines were administered individually or concomitantly. In addition, administering the vaccines in the same or different upper arms did not markedly affect T cell responses. Finally, limited cross-reactivity was observed between the TBEV, JEV, and YFV vaccines, and related ZIKV-specific antigens.

Conclusions

TBEV or JEV vaccines can be co-administered with the live attenuated YFV vaccine without any markedly altered antigen-specific CD4+ and CD8+ T cell responses to the respective flaviviruses. Additionally, the vaccines can be delivered in the same or different upper arms without any significant altered influence on the T cell response. From a broader perspective, these results provide valuable insights into the outcome of immune responses following simultaneous administration of different vaccines for different but related pathogens.
High correlation between detection of dengue IgG from dried blood spots and serum using an indirect IgG ELISA assay: A validation study in Fortaleza, Brazil
Authors: Zahreddine Monica , Parra Beatriz , Pierce Laura , de Oliveira Danielle Ferreira , Carabali Mabel , Charland Katia , Abreu Kellyanne , Ridde Valéry , Lima Danielle Malta , Zinszer Kate
Published: February 2025

Background

Dengue virus (DENV) seroprevalence studies often rely on Enzyme-Linked Immunosorbent Assay (ELISA) testing of serum samples, but ELISA testing of dried blood spot (DBS) samples offer several advantages for field-based research in resource-limited settings. However, DBS’ limited sample volume can be challenging for test sensitivity, requiring validation studies with standard methods (e.g., analysis of serum through ELISAs or Plaque Reduction Neutralization Tests (PRNTs)). In preparation for a large cluster randomized controlled trial, we conducted a pilot study in 2019 to validate the use of DBS compared to serum samples for DENV IgG testing. We aimed to identify the optimal DBS dilution for IgG detection and to estimate the correlation, magnitude of agreement, and sensitivity and specificity of IgG detection in DBS versus serum samples.

Methodology/Principal Findings

We conducted this pilot validation study among 119 healthy participants in Fortaleza, Brazil to evaluate and optimize the detection of DENV IgG from DBS compared to serum. Each participant provided paired DBS and venous blood samples, which were evaluated for DENV IgG using the Panbio Dengue IgG indirect ELISA. DBS elution diluted 1:4 was optimal compared with serum results, with high correlation (r= 0.98) and near-perfect agreement (kappa = 0.95). At this dilution, DBS had a sensitivity of 100%, a specificity of 92.3%, a 97.9% positive predictive value, and a 100% negative predictive value compared with serum.

Conclusions/Significance

These results validate using DBS instead of serum for detection of prior dengue infection among similar populations in endemic regions, without sacrificing test sensitivity and specificity. The validity of using DBS for ELISA to detect prior dengue infection could have important implications for field-based research. A limitation to this study was that the potential for misclassification due to cross-reactivity (e.g., with Zika virus, Yellow Fever vaccine) was not assessed.
Exploring the narrative landscape: The discursive construction of identity for Chinese enterprises in Africa
Authors: Liu Wenyu , Yang Yu
Published: February 2025

This study investigates the construction of corporate identities by Chinese enterprises in Africa, employing the Three-dimensional Model of Fairchough in conjunction with the corporate communication strategies outlined by Kim and Rader. Through an extensive analysis of official website content from 200 Chinese companies, this study explores how these corporations utilize communication strategies to project their identities. The findings reveal a strategic use of discourse to align corporate practices with local cultures and business norms, facilitating their expansion and acceptance in African markets. This study contributes to understanding the dynamic and constructed nature of corporate identities in cross-cultural settings and provides insights into the strategic communication practices of Chinese firms in Africa.
Maternal mortality due to abortion complications in forcibly displaced populations: A study protocol for a community-facility capture-recapture (CFCR) study
Authors: Erhardt-Ohren Blake , Paul Dipika , Mahmud Anik , Tarannum Anika , Weidert Karen , Hossain Altaf , Rubayet Sayed , Prata Ndola
Published: February 2025

There is a paucity of research exploring abortion complication-related morbidity and mortality in humanitarian settings. The most recent data we have to understand the impact of global negligence on forcibly displaced persons’ reproductive health needs in humanitarian emergencies is from the 1999 United Nations Population Fund’s annual report, which estimated that 25-50% of maternal deaths in refugee settings were due to complications from unsafe abortion. This study will investigate maternal death surveillance and reporting (MDSR). The protocol will be implemented in a refugee setting: Forcibly Displaced Myanmar National (FDMN) camps in Cox’s Bazar, Bangladesh. We will review death records for the past twelve months to learn more about how deaths are reported and recorded in facilities and in the camp-in-charge (CiC) office. Following the record review, we will interview individuals who provide reproductive healthcare services to FDMN and participate in MDSR where FDMN reside. These interviews will provide context and depth to the maternal death record review. We will implement a novel community-facility capture-recapture (CFCR) methodology to estimate maternal mortality. This research will fill a gap in knowledge about menstrual regulation, safe abortion and post-abortion access and care, and the measurement of maternal death due to abortion-related complications. This study will provide insights into a new opportunity to potentially more accurately measure maternal mortality due to abortion complications in these settings. The evidence gathered in the course of this research may assist global health practitioners in targeting interventions to prevent unsafe abortion and increase access to safe services that are tailored to forcibly displaced populations. The University of California, Berkeley Center for Protection of Human Subjects (CPHS # 2016-04-8614) and the National Research Ethics Committee (NREC) of the Bangladesh Medical Research Council (BMRC) (Registration # 578 10 03 2024) approved this study protocol.
Prognosis of extracolonic findings on clinical computed tomographic colonography: A single-center experience
Authors: Tomimatsu Hideto , Fujimoto Keita , Suto Taketo , Matsuo Masayuki
Published: February 2025

Computed tomographic colonography (CTC) is crucial for colorectal cancer screening and secondary examinations, often revealing extracolonic findings with unclear significance. This study retrospectively evaluated the impact of such findings on the prognosis and management of 103 patients (mean observation period [OP]: 2183 days), categorized according to the CT Colonography Reporting and Data System (C-RADS). The distributions were 17% (mean OP: 2,821 days) for E1, 38% for E2 (2,759 days), 6% for E3 (2,150 days), and 39% for E4 (1,338 days). Eighteen patients were further examined, but no treatment-related changes were observed in the E2 or E3 cases. Six of nine E4 patients responded to treatment (mean OP: 1,286 days). Kaplan–Meier analysis revealed worse prognosis for E4 (mean survival: 10.1 years) than for E1–E3 combined (5.6 years) (p < 0.0001). E4 findings are key in guiding treatment. The concordance rate between the clinical (Past E) and revised (Revised E) categories was high (0.83, 95% confidence interval: 0.77–0.88). The prognoses differed significantly between Revised E1–E3 (mean survival: 10.0 years) and Revised E4 (6.2 years) (p < 0.0001). Although E4 significantly affects prognosis, E2 and E3 had limited effects on treatment, highlighting the need for further study to improve diagnostic accuracy.
Barriers to and facilitators of rehabilitation according to socio-economic status, after acute respiratory distress syndrome due to COVID-19: A qualitative study in the RECOVIDS cohort
Authors: Kléber Mathilde , Meunier-Beillard Nicolas , Fournel Isabelle , Ksiazek Eléa , Jacquier Marine , Ecarnot Fiona , Rigaud Jean-Philippe , Declerq Pierre-Louis , Quenot Jean-Pierre , Labruyère Marie
Published: February 2025

Background

The COVID-19 pandemic may have compounded social disparities in access to healthcare, with possible deleterious consequences on the functional prognosis of patients after a stay in the intensive care unit (ICU). In the previous RECOVIDS study, we reported that despite comparable pulmonary sequelae and similar access to rehabilitation, socio-economically “vulnerable” patients had lower quality of life at 6 months after an ICU stay. We aimed to describe the barriers to, and facilitators of participation in rehabilitation, among patients from the RECOVIDS study, regardless of their socio-economic situation.

Methods

Qualitative study using semi-structured interviews with adult patients admitted to ICU for PCR-proven SARS-CoV-2 infection, and who had acute respiratory distress syndrome (ARDS) or had received high flow nasal oxygen. In addition, patients had to have been living at home for the month prior to the interview and had to be proficient in French. Eligible patients were randomly selected, aiming to select the same number of socially deprived and non-socially-deprived patients. Interviews were transcribed for thematic analysis.

Results

In total, 31 interviews were performed from 10/2021 to 01/2022; 16 with socially deprived, and 15 with non-deprived participants. Average age was 65.2 (±11.6) years. Four themes emerged from the analysis of the interviews, namely: (1) the impact of the patient’s professional and socio-economic situation; (2) the feeling that age and socio-economic situation influence access to rehabilitation; (3) a perception that the healthcare system was saturated, and that inequalities exist in access to rehabilitation resources; (4) perception of previous own health and expectations of post-resuscitation health status.

Conclusion

A precarious socio-economic situation has a substantial impact on access to rehabilitation after ICU admission for ARDS caused by COVID-19. It represents a barrier to rehabilitation through the combined action of various social determinants that deserve to be detected early, in order to take appropriate action to ensure that the most socially vulnerable individuals can benefit from access to rehabilitation.
Smart waste classification in IoT-enabled smart cities using VGG16 and Cat Swarm Optimized random forest
Authors: Gaurav Akshat , Gupta Brij Bhooshan , Arya Varsha , Attar Razaz Waheeb , Bansal Shavi , Alhomoud Ahmed , Chui Kwok Tai
Published: February 2025

Effective waste management is becoming a crucial component of sustainable urban development as smart technologies are used by smart cities more and more. Smart trash categorization systems provided by IoT may greatly enhance garbage sorting and recycling mechanisms. In this context, this work presents a waste categorization model based on transfer learning using the VGG16 model for feature extraction and a Random Forest classifier tuned by Cat Swarm Optimization (CSO). On a Kaggle garbage categorization dataset, the model outperformed conventional models like SVM, XGBoost, and logistic regression. With an accuracy of 85% and a high AUC of 0.85 the Random Forest model shows better performance in precision, recall, and F1-score as compared to standard machine learning models.