Polystyrene Chain Geometry Probed by Ion Mobility Mass Spectrometry and Molecular Dynamics Simulations.

Polystyrene (PS) is a thermoplastic polymer commonly used in various applications due to its bulk properties. Designing functional polystyrenes with well-defined structures for targeted applications is of significant interest due to the rigid and apolar nature of the polymer chain. Progress is hindered to date by the limitations of current analytical methods in defining the atomistic-level folding of the polymer chain. The integration of ion mobility spectrometry and molecular dynamics simulations is beneficial in addressing these challenges. However, data on gas-phase polystyrene ions are rarely reported in the literature. We herein investigate the gas phase structure of polystyrene ions with different end groups to establish how the nature and the rigidity of the monomer unit affect the charge stabilization. We find that, in contrast to polar polymers in which the charges are located deep in the ionic globules, the charges in the PS ions are rather located at the periphery of the polymer backbone, leading to singly and doubly charged PS ions adopting dense elliptic-shaped structures. Molecular dynamics (MD) simulations indicate that the folding of the PS rigid chain is controlled by phenyl ring interactions with the charge ultimately remaining excluded from the core of the globular ions, whereas the folding of polyether ions is initiated by the folding of the flexible polyether chain around the sodium ion that remains deeply enclosed in the core of the ions.

Which are the most effective methods of teaching sectional anatomy? A scoping review.

PURPOSE: Sectional anatomy knowledge is essential for a wide spectrum of health professionals and is extensively applied to their everyday practice. We performed a scoping review to find which are the most effective methods of teaching sectional anatomy. METHODS: We searched PubMed, Scopus, and Cochrane Library to detect articles which investigated the effectiveness of sectional anatomy education methods, based on test scores. From each included paper, we extracted: author(s), number of participants, the anatomical region or regions, the method or methods of sectional anatomy education and the outcomes concerning only the acquisition of sectional anatomy knowledge. RESULTS: Seven studies were included. There were four articles, which involved combined teaching approaches, and three articles, which did not comprise such approaches. In all studies which evaluated the effectiveness of a combination of teaching methods (comprising three-dimensional digital or physical tools) compared to cross-sections only, the anatomy test scores were significantly higher in the first case. The students' interaction with the educational material significantly enhanced the effectiveness of the implemented methods. CONCLUSIONS: The multimodal teaching of sectional anatomy, especially involving three-dimensional methods, both digital and physical, was more effective than teaching based only on cross-sections. The students' interaction with the educational material improved the effectiveness of the teaching, which they received. These outcomes may stimulate anatomy teachers to enhance sectional anatomy education and encourage researchers to shed more light on the investigation of the optimal teaching strategies.

The Performance and Fabrication of 3D Variable Cross-Section Channel for Passive Microfluidic Control.

Passive fluid control has mostly been used for valves, pumps, and mixers in microfluidic systems. The basic principle is to generate localized losses in special channel structures, such as branches, grooves, or spirals. The flow field in two-dimensional space can be easily calculated using the typical Stokes formula, but it is challenging in three-dimensional space. Moreover, the flow field with periodic variable cross-sections channeled of polyhedral units has been neglected in this research field due to previous limitations in manufacturing technology. With the continuous progress of 3D printing technology, the field of microfluidic devices ushered in a new era of manufacturing three-dimensional irregular channels. In this study, we present finite analysis results for a periodic nodular-like channel. The experiments involve variations in the Reynold number (Re), periodic frequency, and comparative analyses with conventional structures. The findings indicate that this variable 3D cross-section structure can readily achieve performance comparable to other passive fluid control methods in valve applications. A 3D model of the periodic tetrahedron channel was fabricated using 3D printing to validate these conclusions. This research has the potential to significantly enhance the performance of passive fluid control units that have long been constrained by manufacturing dimensions.

A study on neutron emission for proton-induced reactions in 90Zr, 91Zr, and 115In isotopes.

Fusion energy heralds the potential of a transformative era, offering a significant solution to global challenges such as climate change, ozone depletion and environmental pollution. Despite its promising prospects, the commercialization of fusion faces several challenges, including high temperature, pressure, plasma stability, fuel supply, costs, etc. It is important to effectively analyze material behavior under plasma conditions, especially in environments where fusion reactions produce high-energy particles such as neutrons. This study investigates the angle-dependent neutron production mechanisms of proton-induced reactions involving the isotopes 90Zr, 91Zr and 115In, which are widely used in fusion reactor materials. Using the Monte Carlo codes PHITS 3.32 and FLUKA, as well as the TALYS 1.96 code, double differential cross-section calculations for neutron emission were performed considering various angles. The research contributes to a broader understanding of fusion processes by providing insights into the behavior of these isotopes under proton-induced reactions.

Bond Shear Tests to Evaluate Different CFRP Shear Strengthening Strategies for I-Shaped Concrete Cross-Sections.

I-shaped concrete girders are widely used in precast bridge and roof construction, making them a common structural component in existing infrastructure. Despite well-established strengthening techniques using various innovative materials, such as externally bonded carbon fibre reinforced polymer (CFRP) reinforcement, the shear strengthening of an I-shaped concrete girder is not straightforward. Several research studies have shown that externally bonded CFRP reinforcement might exhibit early debonding at the concave corners of the I-shape, resulting in a marginal increase in shear capacity. This research study aims to assess the performance of two different CFRP shear strengthening strategies for I-shaped concrete cross-sections. In the first strategy, CFRP was bonded along the I-shape of the cross-section with the provision of additional anchorage. In the second strategy, the I-shape was transformed into a rectangular shape by using in-fill blocks over which the CFRP was bonded in a U-configuration. In addition to the strengthening strategies, the investigated parameters included two different materials for the in-fill blocks (conventional and aerated concrete) and two different anchoring schemes (bolted steel plate anchor and CFRP spike anchor). To avoid testing on large-scale girders, a new test methodology has been implemented on concrete I-sections. The test results demonstrate the feasibility of comparing different shear strengthening configurations dedicated to I-sections. Among other findings, the results showed that the local transformation of the I-shape to an equivalent rectangular shape could be a viable solution, resulting in shear strength enhancement of 12% to 53% without and with the anchorages, respectively.

Head of Zebu cattle (Bos Taurus indicus): sectional anatomy and 3D computed tomography.

The research was designed to use computed tomography (CT) with 3D-CT reconstruction imaging techniques and the various anatomical sections-plana transversalia, frontalis, and dorsalia-to describe the anatomical architecture of the Zebu cattle head. Our study used nine mature heads. The CT bone window created detailed images of cranial bones, mandibles, teeth, and hyoid bones. All of the head cavities were evaluated, including the cranial, orbital, oral, auricular, and nasal cavities with their paranasal and conchal sinuses. The septum nasi, attached to the vomer and maxillary bones, did not reach the nasal cavity floor caudally at the level of the second premolar teeth, resulting in a single median channel from the choanae to the nasopharynx. The positions, boundaries, and connections of the paranasal sinuses were clearly identified. There were four nasal conchal sinuses (that were named the dorsal, middle, ethmoidal, and ventral) and five paranasal sinuses that were described as the following: sinus frontalis, maxillaris, palatinorum, and lacrimalis, as defined in the different anatomical sections and computed tomographic images. The complicated sinus frontalis caused the pneumatization of all bones that surrounded the cranial cavity, with the exception of the ethmoidal and body of basisphenoid bones. The sinus maxillaris was connected to the sinus lacrimalis and palatinorum through the maxillolacrimal and palatomaxillary openings, and to the middle nasal meatus through the nasomaxillary opening. Our findings provide a detailed anatomical knowledge for disease diagnosis to internal medicine veterinarians and surgeons by offering a comprehensive atlas of the Zebu cattle anatomy.

Estimating body volumes and surface areas of animals from cross-sections.

Background: Body mass and surface area are among the most important biological properties, but such information is lacking for some extant organisms and most extinct species. Numerous methods have been developed for body size estimation of animals for this reason. There are two main categories of mass-estimating approaches: extant-scaling approaches and volumetric-density approaches. Extant-scaling approaches determine the relationships between linear skeletal measurements and body mass using regression equations. Volumetric-density approaches, on the other hand, are all based on models. The models are of various types, including physical models, 2D images, and 3D virtual reconstructions. Once the models are constructed, their volumes are acquired using Archimedes' Principle, math formulae, or 3D software. Then densities are assigned to convert volumes to masses. The acquisition of surface area is similar to volume estimation by changing math formulae or software commands. This article presents a new 2D volumetric-density approach called the cross-sectional method (CSM). Methods: The CSM integrates biological cross-sections to estimate volume and surface area accurately. It requires a side view or dorsal/ventral view image, a series of cross-sectional silhouettes and some measurements to perform the calculation. To evaluate the performance of the CSM, two other 2D volumetric-density approaches (Graphic Double Integration (GDI) and Paleomass) are compared with it. Results: The CSM produces very accurate results, with average error rates around 0.20% in volume and 1.21% in area respectively. It has higher accuracy than GDI or Paleomass in estimating the volumes and areas of irregular-shaped biological structures. Discussion: Most previous 2D volumetric-density approaches assume an elliptical or superelliptical approximation of animal cross-sections. Such an approximation does not always have good performance. The CSM processes the true profiles directly rather than approximating and can deal with any shape. It can process objects that have gradually changing cross-sections. This study also suggests that more attention should be paid to the careful acquisition of cross-sections of animals in 2D volumetric-density approaches, otherwise serious errors may be introduced during the estimations. Combined with 2D modeling techniques, the CSM can be considered as an alternative to 3D modeling under certain conditions. It can reduce the complexity of making reconstructions while ensuring the reliability of the results.

Sciatic nerve fascicle differentiation on high-resolution ultrasound with histological verification: An ex vivo study.

INTRODUCTION/AIMS: The development of high-resolution ultrasound (HRUS) has enabled the depiction of peripheral nerve microanatomy in vivo. This study compared HRUS fascicle differentiation to the structural depiction in histological cross-sections (HCS). METHODS: A human cadaveric sciatic nerve was marked with 10 surgical sutures, and HRUS image acquisition was performed with a 22-MHz probe. The nerve was excised and cut into five segments for HCS preparation. Selected HCS were cross-referenced to HRUS, with sutures to improve orientation. Sciatic nerve and fascicle contouring were performed to assess nerve and fascicular cross-sectional area (CSA), fascicle count, and interfascicular distances. Three groups were defined based on HRUS fascicle differentiation in comparison to HCS, namely single fascicle (SF), fascicular cluster (FC), and no depiction (ND) group. RESULTS: On cross-referenced HRUS to HCS images, 58% of fascicles were differentiated. On HRUS, significantly larger fascicle CSA and smaller fascicle count were observed compared with HCS. Group analysis showed that 41% of fascicles were defined as SF, 47% as FC, and 12% as ND. The mean fascicle CSA in the ND group was 0.05 mm2. Compared with the SF, the FC had significantly larger fascicle CSA (1.2 ± 0.7 vs. 0.6 ± 0.4 mm2; p < .001) and shorter interfascicular distances (0.1 ± 0.04 vs. 0.5 ± 0.3 µm; p < .001). DISCUSSION: While HRUS can depict fascicular anatomy, only half of the fascicles visualized on HRUS directly correspond to single fascicles observed on HCS. The amount of interfascicular epineurium appears to influence the ability of HRUS to differentiate individual fascicles.

Ionization Detail Parameters for DNA Damage Evaluation in Charged Particle Radiotherapy: Simulation Study Based on Cell Survival Database.

Details of excitation and ionization acts hide a description of the biological effects of charged particle traversal through living tissue. Nanodosimetry enables the introduction of novel quantities that characterize and quantify the particle track structure while also serving as a foundation for assessing biological effects based on this quantification. This presents an opportunity to enhance the planning of charged particle radiotherapy by taking into account the ionization detail. This work uses Monte Carlo simulations with Geant4-DNA code for a wide variety of charged particles and their radiation qualities to analyze the distribution of ionization cluster sizes within nanometer-scale volumes, similar to DNA diameter. By correlating these results with biological parameters extracted from the PIDE database for the V79 cell line, a novel parameter R2 based on ionization details is proposed for the evaluation of radiation quality in terms of biological consequences, i.e., radiobiological cross section for inactivation. By incorporating the probability p of sub-lethal damage caused by a single ionization, we address limitations associated with the usually proposed nanodosimetric parameter Fk for characterizing the biological effects of radiation. We show that the new parameter R2 correlates well with radiobiological data and can be used to predict biological outcomes.

Study of activation cross sections of double neutron capture reaction on 193Ir for the reactor production route of radiotherapeutic 195mPt.

The radiotherapeutic 195mPt is among the most effective Auger electron emitters of the currently studied radionuclides that have a potential theranostic application in nuclear medicine. Production of 195mPt through double neuron capture of enriched 193Ir followed by ß--decay to the radioisotope of interest carried out at the research reactor IBR-2 is described. Because of the high radiation background, radiochemical purification procedure of 195mPt from bulk of iridium was needed to be developed and is detailed here as well. For the first time, cross section and resonance integral for the reaction 194Ir(n,γ)195mIr were determined. Resonance neutrons contribution was established to exceed that of thermal neutrons, and resonance integral for the reaction 194Ir(n,γ)195mIr is calculated to be 2900 b. Specific activity of 195mPt was estimated to reach a value of 38.7 GBq/(g Pt) at IBR-2 by the end of bombardment (EOB).

Application of pseudo-parameter iteration method to nonlinear deflection analysis of an infinite beam with variable beam cross-sections on a nonlinear elastic foundation.

In this study, the nonlinear deflection of an infinite beam with variable beam cross-sections on a nonlinear elastic foundation was analyzed using the pseudo-parameter iteration method (PIM), which is a novel iterative semi-analytic method for solving ordinary/partial differential equations. To do this, we set six types of infinite beams with concave and convex shapes under static loading conditions. To calculate the nonlinear deflection of the infinite beam with variable cross-sections, the Bernoulli-Euler beam equation (fourth-order ordinary differential equation) considering changing beam flexural rigidity was introduced, and the PIM was adopted to this equation. Through the numerical experiment, it was confirmed that the nonlinear deflections calculated via the PIM are quite close to the exact solution within a few iterations. In addition, the graph of error quickly reaches the steady state error for all cases as the number of iterations increases.

The spectrum-averaged cross section investigation of 117Sn(n,n')117mSn and 67Zn(n,p)67Cu reactions.

The spectrum averaged cross sections (SACS) in standard neutron field, e.g. 252Cf(s.f.), is a preferable tool for cross section evaluation and validation. A set of reaction measurements with high energy thresholds was previously performed. The presented work focuses on lower energy threshold reactions, namely on the inelastic scattering of the tin foil, more specifically the reaction 117Sn(n,n')117mSn, and the zinc foil reaction, namely 67Zn(n,p)67Cu. These reactions are of special interest due to their intermediate energy range, which is essential in classical reactor dosimetry and fast reactor dosimetry. The experiments were carried out in a standard neutron field formed by 252Cf(s.f.) source in Rez. The experimental results were compared with calculations using MCNP6.2, ENDF/B-VII.1 transport library, and ENDF/B-VIII.0 and IRDFF-II cross section data library. Additionally, the calculations using CEA code DARWIN/PEPIN2 using JEFF-3.0/A were executed. The obtained experimental SACS of previously measured reactions were in good agreement with the SACS calculated using the IRDFF-II library. Additionally, the calculational reaction rate of 67Zn(n,p)67Cu was in accordance with the experimental data in case of ENDF/B-VIII.0 nuclear data library. Moreover, the calculational results of 117Sn(n,n')117mSn obtained by DARWIN/PEPIN2 code (using JEFF-3.0/A nuclear data library) are closest to the experimental results.

Structural Insights into Linkage-Specific Ubiquitin Chains Using Ion Mobility Mass Spectrometry.

The structural characterization and differentiation of four types of oligoubiquitin conjugates [linear (Met1)-, Lys11-, Lys48-, Lys63-linked di-, tri-, and tetraubiquitin chains] using ion mobility mass spectrometry are reported. A comparison of collision cross sections for the same linkage of di-, tri-, and tetraubiquitin chains shows differences in conformational elongation for higher charge states due to the interplay of linkage-derived structure and Coulombic repulsion. For di- and triubiquitin chains, this elongation results in a single narrow feature representing an elongated conformation type for multiple higher charge state species. In contrast, higher charge state tetraubiquitin species do not form a single conformer type as readily. A comparison of different linkages in tetraubiquitin chains reveals greater similarity in conformation type at lower charge states; with increasing charge state, the four linkage types diverge in the relative proportions of elongated conformer types with Met1- ≥ Lys11- > Lys63- > Lys48-linkage. These differences in conformational trends could be discussed with respect to biological functions of linkage-specific polyubiquitinated proteins.

Correlation between Cross-Sectional Anatomy and Computed Tomography of the Normal Six-Banded Armadillo (Euphractus sexcintus) Nasal Cavity and Paranasal Sinuses.

This research aimed to study the rostral part of the head of the six-banded armadillo, applying advanced imaging techniques such as CT. Furthermore, by combining the images obtained through this technique with anatomical cross-sections, an adequate description of the structures that constitute the rostral part of the head of this species is presented. This anatomical information could provide a valuable diagnostic tool for the clinical evaluation of different disorders in the six-banded armadillo's nasal cavity and paranasal sinuses.

Ionization Cross Sections of Hydrogen Molecule by Electron and Positron Impact.

We present ionization cross sections of hydrogen molecules by electron and positron impact for impact energies between 20 and 1000 eV. A three-body Classical Trajectory Monte Carlo approximation is applied to mimic the collision system. In this approach, the H2 molecule is modeled by a hydrogen-type atom with one active electron bound to a central core of effective charge with an effective binding energy. Although this model is crude for describing a hydrogen molecule, we found that the total cross sections for positron impact agree reasonably well with the experimental data. For the electron impact, our calculated cross sections are in good agreement with the experimental data in impact energies between 80 eV and 400 eV but are smaller at higher impact energies and larger at lower impact energies. Our calculated cross sections are compared with the scaled cross sections obtained experimentally for an atomic hydrogen target. We also present single differential cross sections as a function of the energy and angle of the ejected electron and scattered projectiles for a 250 eV impact. These are shown to agree well with available data. Impact parameter distributions are also compared for several impact energies.

Analyzing neutron emission cross sections for 22.2 MeV proton-induced reactions on 58Ni and 52Cr.

Double differential cross-section calculations were performed for proton-induced reactions with 58Ni and 52Cr isotopes using Monte Carlo code PHITS 3.32 and TALYS 1.96. Comparative analyses with experimental data from the EXFOR library demonstrated the effectiveness of the CTFGM and BSFGM models in conjunction with the TALYS nuclear code program for (p,xn) reactions across all angular values. While the GSM model exhibited consistency regardless of the angle, FLUKA and PHITS showed some discrepancies depending on the angle, particularly at small angle values.

44Sc production from enriched 47TiO2 targets with a medical cyclotron.

44Sc is a ß+-emitter which has been extensively studied for nuclear medicine applications. Its promising decay characteristics [t1/2 = 3.97 h, E [Formula: see text] = 632 keV (94.3%), Eγ = 1157 keV (99.9%); 1499 keV (0.91%)] make it highly attractive for clinical PET imaging, offering an alternative to the widely used 68Ga [t1/2 = 67.7 min, E [Formula: see text] = 836 keV (87.7%)]. Notably, its nearly fourfold longer half-life opens avenues for applications with biomolecules having extended biological half-lives and enables the centralized distribution of 44Sc radiopharmaceuticals. An additional advantage of employing 44Sc as a diagnostic radioisotope lies in its counterpart, the ß--emitter 47Sc, which is currently under investigation for targeted radiotherapy. Together, they form an ideal theranostic pair, providing a comprehensive solution for both diagnostic imaging and therapeutic applications in nuclear medicine. At the Bern medical cyclotron, a study to optimize the production of scandium radioisotopes is currently ongoing. In this context, proton irradiation of titanium targets has been investigated, exploiting the reactions 47Ti(p,α)44Sc and 50Ti(p,α)47Sc. This approach enables the production of Sc radioisotopes within a single PET medical cyclotron facility, employing identical chemical procedures for target preparation and post-irradiation processing. In this paper, we report on cross-section measurements of the 47Ti(p,α)44Sc nuclear reaction using 95.7% enriched 47TiO2 targets. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. Production tests were performed to confirm these findings.

Estimate of the C-Cl photoionization cross section and absolute photoionization cross sections of chlorinated organic compounds.

Chlorinated organic compounds are prominently used for industrial production, but their vapors and emission byproducts can cause detrimental effects to human health and the environment. To accurately quantify organochlorine compounds, the absolute photoionization cross section of tetrachloroethylene, chlorobenzene, 1,2-dichlorobenzene, and chloroacetone are measured using multiplexed synchrotron photoionization mass spectrometry at the Advanced Light Source at Lawrence Berkeley National Laboratory. These measurements allow for the estimation of the C-Cl photoionization cross section, increasing quantification accuracy of chlorinated emissions for kinetic modeling and pollutant mitigation. CBS-QB3 calculations of adiabatic ionization energies and thermochemical appearance energies are also presented and agree well with the experimental results.

Absolute Photoionization Cross Section and Dissociative Ionization Pathways of Alpha-Pinene.

The absolute photoionization cross section of the monoterpenoid, alpha-pinene (AP), is presented together with the relative photoionization cross sections of its dissociative fragments for the first time. Experiments are performed via multiplexed vacuum ultraviolet (VUV) synchrotron photoionization (PI) mass spectrometry in the 8.0-11.0 eV energy range. Experimental work is conducted at the Advanced Light Source of the Lawrence Berkeley National Laboratory. Dissociative fragments were identified at m/z 121, 94, 93, 92, and 80. The photoionization cross section for the parent mass at 11.0 eV was determined to be 17±4 Mb with a total ionization cross section of 92±23 Mb at the same photon energy. Experimental appearance energies of dissociative ionization fragments and potential dissociative ionization pathways calculated at the G4 level of theory are presented as well.

Neural network predictions of (α,n) reaction cross sections at 18.5±3 MeV using the Levenberg-Marquardt algorithm.

In recent developments, artificial neural networks (ANNs) have demonstrated their capability to predict reaction cross-sections based on experimental data. Specifically, for predicting (α,n) reaction cross-sections, we meticulously fine-tuned the neural network's performance by optimizing its parameters through the Levenberg-Marquardt algorithm. The effectiveness of this approach is corroborated by notable correlation coefficients; an R-value of 0.90928 for overall correlation, 0.98194 for validation, 0.99981 for testing, and 0.94116 for the comprehensive network prediction. We conducted a rigorous comparison between the results and theoretical computations derived from the TALYS 1.95 nuclear code to validate the predictive accuracy. The mean square error value for artificial neural network results is 7620.92, whereas for TALYS 1.95 calculations, it has been found to be 50,312.74. This comprehensive evaluation process validates the reliability of the ANN based on the Levenberg-Marquardt algorithm in approximating the reaction sections, thus demonstrating its potential for comprehensive investigations. These recent developments confirm the feasibility of using ANN models to gain insight into (α,n) reaction cross-sections.