bluuebunny/crossref_metadata_2025 huggingface dataset:
The chemical effect of furfuryl amide on the enhanced performance of the diphenolic acid derived bio‐polybenzoxazine resin
Authors: Qian Zizhao , Li Qing , Wang Lujie , Fu Feiya , Liu Xiangdong
Published: July 2021

As a renewable chemical, diphenolic acid (DPA) has attracted immense interest in bio‐based polymer science. However, its application for polybenzoxazines is limited due to decarboxylation, that is, the release of CO2 during the curing reaction of benzoxazine. In this study, the amidation strategy of converting DPA to diphenolic amides (DPAM) was demonstrated to solve this problem while simultaneously improving the thermal properties of polybenzoxazine. DPA was amidated by separately using four amines (hexamine, cyclohexylamine, furfurylamine, and aniline), then reacted with furfurylamine and paraformaldehyde to synthesize their benzoxazine monomers. By using TGA and DMA, all amide‐containing polybenzoxazines were found to exhibit excellent thermal stabilities. Among all of the benzoxazine resins, poly(DFA‐fa), which was obtained from amidation with furfurylamine, exhibited the highest glass transition temperature (Tg) of 310°C and a decomposition temperature (Td10) of 406°C. Furthermore, a possible post‐curing reaction mechanism was proposed to explain the outstanding thermal performance of poly(DFA‐fa) resin. This study proposes an innovative strategy to solve the decarboxylation of DPA‐based polymers, which is of significance for high‐performance bio‐based polymers.
Reduced pediatric urgent asthma utilization and exacerbations during the COVID‐19 pandemic
Authors: Hurst Jillian H. , Zhao Congwen , Fitzpatrick Nicholas S. , Goldstein Benjamin A. , Lang Jason E.
Published: July 2021

The COVID‐19 pandemic has had a profound impact on healthcare access and utilization, which could have important implications for children with chronic diseases, including asthma. We sought to evaluate changes in healthcare utilization and outcomes in children with asthma during the COVID‐19 pandemic. We used electronic health records data to evaluate healthcare use and asthma outcomes in 3959 children and adolescents, 5–17 years of age, with a prior diagnosis of asthma who had a history of well‐child visits and encounters within the healthcare system. We assessed all‐cause healthcare encounters and asthma exacerbations in the 12‐months preceding the start of the COVID‐19 pandemic (March 1, 2019–February 29, 2020) and the first 12 months of the pandemic (March 1, 2020–February 28, 2021). All‐cause healthcare encounters decreased significantly during the pandemic compared to the preceding year, including well‐child visits (48.1% during the pandemic vs. 66.6% in the prior year; p < .01), emergency department visits (9.7% vs. 21.0%; p < .01), and inpatient admissions (1.6% vs. 2.5%; p < .01), though there was over a 100‐fold increase in telehealth encounters. Asthma exacerbations that required treatment with systemic steroids also decreased (127 vs. 504 exacerbations; p < .01). Race/ethnicity was not associated with changes in healthcare utilization or asthma outcomes. The COVID‐19 pandemic corresponded to dramatic shifts in healthcare utilization, including increased telehealth use and improved outcomes among children with asthma. Social distancing measures may have also reduced asthma trigger exposure.
DynaBiS: A hierarchical sampling algorithm to identify flexible binding sites for large ligands and peptides
Authors: Melse Okke , Hecht Sabrina , Antes Iris
Published: July 2021

Knowing the ligand or peptide binding site in proteins is highly important to guide drug discovery, but experimental elucidation of the binding site is difficult. Therefore, various computational approaches have been developed to identify potential binding sites in protein structures. However, protein and ligand flexibility are often neglected in these methods due to efficiency considerations despite the recognition that protein–ligand interactions can be strongly affected by mutual structural adaptations. This is particularly true if the binding site is unknown, as the screening will typically be performed based on an unbound protein structure. Herein we present DynaBiS, a hierarchical sampling algorithm to identify flexible binding sites for a target ligand with explicit consideration of protein and ligand flexibility, inspired by our previously presented flexible docking algorithm DynaDock. DynaBiS applies soft‐core potentials between the ligand and the protein, thereby allowing a certain protein–ligand overlap resulting in efficient sampling of conformational adaptation effects. We evaluated DynaBiS and other commonly used binding site identification algorithms against a diverse evaluation set consisting of 26 proteins featuring peptide as well as small ligand binding sites. We show that DynaBiS outperforms the other evaluated methods for the identification of protein binding sites for large and highly flexible ligands such as peptides, both with a holo or apo structure used as input.
Computational study of ammonia generation by iron(III) and iron(IV) complexes supported by trigonal bipyramidal iron
Authors: Vyas Nidhi , Sen Asmita , Kumar Aditya , Grover Abhinav
Published: July 2021

High‐valent species such as terminal iron nitrides (FeN) are carried out for many organic and inorganic transformations. Simultaneously, they provide significant insight into the reactivity of various metalloenzyme as they involved in the reaction of nitrogenase enzyme. Various biomimetic model complexes were reported to understand nitrogenase enzyme's reactivity. In this framework, Peters et al. have published the facile formation of intermediate species [(TPB)FeIII/IVN]0/1+ from the complex [(TPB)FeN2] (here, TPB = tris(o‐diisopropylphosphinophenyl) borane. However, all species were thoroughly synthesized and characterized. But the mechanism is still elusive in terms of reactivity and the roles of intermediate species. In this work, we have tried to explore the mechanism of ammonia generation from these high‐valent [(TPB)FeIII/IVN]0/1+ species employing the experimental conditions. Our computed results shows a very small energy barrier of 6.7 kJ/mol for the first transition state of protonation by the [(TPB)FeIIIN] species (path1) in the NH bond activation of path1, however comparatively large energy barrier was reported for path2. From this reaction mechanism, it is established that species [(TPB)FeIIIN] is more reactive than [(TPB)FeIVN]+. The reactivity difference between these two species is mainly due to the nature of FeN bond, its basicity and electron delocalization during the NH bond activation. Comprehensive electronic structure investigation of the transition state reveals that the substrate will follow the low energy σ‐type pathway and the electron from the NH bond electron will go in the σz2 orbital. However, the high‐energy π‐type pathway, where the NH bond electron will go in the π*xz orbital. The spectroscopic parameters (Absorption, and Mössbauer) computed for some species, are compared to experimental observation to get belief on the computed data.
Revisiting the relationship between sustainable project management and project success: The moderating role of stakeholder engagement and team building
Authors: Shaukat Mohammad Bilal , Latif Khawaja Fawad , Sajjad Aymen , Eweje Gabriel
Published: July 2021

This paper examines the relationship between sustainable project management (SPM) and project success with the moderating effect of stakeholder engagement and team building on this relationship. A structured survey questionnaire technique was applied for data collection and 323 responses were received from project management professionals in Pakistan. The results revealed that SPM has a positive impact on project success. However, the effects of stakeholder engagement and team building were found insignificant. Accordingly, this paper contributes to SPM literature by demonstrating the relationship between SPM and project success in a developing world context. From a practical viewpoint, firms need to consider SPM from a holistic perspective by embracing and incorporating key sustainability aspects into various project life‐cycle stages. To this end, project managers not only need to promote stakeholder engagement and team‐building strategies, but also scrutinize all important project decisions from a sustainability lens to further enhance SPM outcomes and create a meaningful value proposition for each stakeholder group, which are increasingly recognized as critical issues for project success.
Facile Synthesis of an Mg‐incorporated ZSM‐5 Zeolite from Dual Silicon Sources and Its Application for Conversion of Methanol to Olefins
Authors: Chen Xueshuai , Jiang Rongli , Hou Huilin , Zhou Zihan , Wang Xingwen
Published: July 2021

In this work, an Mg‐incorporated ZSM‐5 zeolite with superior catalytic properties is synthesized directly from dual silicon sources(laponite and tetraethylorthosilicate) as raw material via hydrothermal method. The ZSM‐5 synthesized from laponite as one of the Si sources exhibits unique aggregated spherical morphology composed of sheet‐like crystals, which is due to the depolymerized laponite can act as crystalline seeds and facilitate the ZSM‐5 zeolite nucleation. Furthermore, the Mg species in laponite can subsequently enter into the ZSM‐5 zeolite during the process of crystallization. In comparison with ZSM‐5(0) synthesized by using tetraethylorthosilicate(TEOS) as single Si source, ZSM‐5 zeolite synthesized from dual silicon sources exhibited better catalytic performace for MTO reaction. Our work provides a straightforward and green route for the synthesis of an Mg‐incorporated ZSM‐5 zeolite from dual silicon sources with excellent MTO performance.
Synthesis, Biological Evaluation, Molecular Docking, and Acid Dissociation Constant of New Bis‐1,2,3‐triazole Compounds
Authors: Nural Yahya , Ozdemir Sadin , Yalcin Mustafa Serkan , Demir Bunyamin , Atabey Hasan , Ece Abdulilah , Seferoglu Zeynel
Published: July 2021

In this study, new bis‐1,2,3‐triazole derivatives, N,N′‐(1,3‐phenylene)bis(2‐(4‐R‐1H‐1,2,3‐triazol‐1‐yl)acetamide), were synthesized by copper‐catalyzed azide‐alkyne cycloaddition click chemistry in 84–96 % yield. A wide range bioactivity screening was performed to determine DNA cleavage, antioxidant, antibacterial and antifungal activities. All of the synthesized bis‐1,2,3‐triazoles showed excellent DNA cleavage activity and 4 e, bearing 2‐bromoethyl moiety as a substituent, was almost degraded all of the plasmid DNA. Molecular docking simulations suggest that the synthesized compounds act as minor groove binders of DNA. The antioxidant activities of the bis‐1,2,3‐triazoles were determined based on the radical scavenging effect of the stable 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical and iron chelating activity. The compounds exhibited effective iron chelating activity at 200 mg/L while showing a moderate ability to scavenge DPPH radical. The compounds exhibited antibacterial activity against B. cereus, L. pneumophila subsp. pneumophila, S. aureus, P. aeruginosa, E. coli and E. hirae bacterial strains, and antifungal activity against C. albicans and C. tropicalis microfungus strains with a MIC value in the range of 4–128 μg/mL. 4 d, bearing cyclohexylmethyl moiety as substituent, exhibited a broad‐spectrum antimicrobial activity (both antibacterial and antifungal). Four different acid dissociation constant (pKa) values of each product were determined potentiometrically in 20 % (v/v) dimethyl sulfoxide‐water at 25±0.1 °C, at an ionic background of 0.1mol/L of NaCl using the HYPERQUAD program.
DFT Studies of Substituted Phenols Cytotoxicity I. Para‐substituted Phenols
Authors: Štekláč Marek , Breza Martin
Published: July 2021

New type of cytotoxicity descriptors based on Cu(II) coordination ability of p‐substituted phenols and subsequent O→Cu electron density transfer is introduced. Geometries of phenols and of their Cu(II) complexes are optimized at the DFT level of theory. The amount of electron density transfer is evaluated using the copper charge or the electron density Laplacian at the Cu−O bond critical point. The Cu‐phenol interaction energy is a measure of the phenol reactivity. Statistical parameters for the linear dependence of the published cytotoxicity data on the above predictors are much better than the classical ones.
High‐Performance Fullerene Free Polymer Solar Cells Based on New Thiazole ‐Functionalized Benzo[1,2‐b:4,5‐b′]dithiophene D‐A Copolymer Donors
Authors: Keshtov Mukhamed. L. , Konstantinov Igor O. , Kuklin Sergei A. , Khokhlov Aleksei R. , Ostapov Ilya E. , Xie Zhiyuan , Komarov Pavel V. , Alekseev Vladimir G. , Dahiya Hemraj , Sharma Ganesh D.
Published: July 2021

Two new wide bandgaps D−A copolymers compromising of same benzo [1,2‐b:4, 5‐b′]dithiophene functionalized with thiazole side‐chain donor unit and different acceptors units, i. e., fluorinated benzotriazole (FBTA) (PBDTTZ‐FBTA) and bis‐thiophene‐thieno‐benzothiazole (BTZ) (PBDTTZ‐BTZ) were synthesized and their optical and electrochemical properties were investigated. These copolymers exhibit appropriate frontier energy levels and complementary absorption to most middle and narrow bandgap non‐fullerene small molecule non‐fullerene acceptors. We have explored using these two copolymers as donors combined with a narrow bandgap non‐fullerene acceptor, namely BThIND−Cl, for the construction of polymer solar cells. The optimized polymer solar cells employing PBDTTZ‐FBTA: BThIND−Cl showed overall power conversion efficiency of 14.96 % (with energy loss of 0.51 eV), which is higher than that for PBDTTZ‐BTZ: BThIND−Cl (11.68 % with energy loss of 0.56 eV). Although the PBDTTZ‐BTZ exhibits a broader absorption profile than that of PBDTTZ‐FBTA, the higher power conversion efficiency of the later copolymer may be correlated with the high charge carrier mobility, suppression of the bimolecular and trap‐assisted recombination due to appropriate phase separation and compact π‐π stacking distance in the active layer and low energy loss.
Enhanced Solubility and Oral Bioavailability of Hydrophobic Drugs Using Pluronic Nanomicelles: An In‐Vitro Evaluation
Authors: Shaikh Sofiya J. , Patel Hemil S. , Ray Debes , Aswal Vinod K. , Singh Sushmita , Vijayvargia Ravi , Sheth Urjita , Sharma Rakesh K.
Published: July 2021

Poor drug solubility and oral bioavailability is a significant challenge with many effective drug candidates. Pluronic micelles are effective solutions for improved solubility, stability, and delivery of the hydrophobic drug to the right area, at the right time, and in the right amount. Solubilization of three drugs, namely curcumin (CUR), quercetin (QCN), and lamotrigine (LTG), were explored using Pluronics with varying molecular characteristics. All the drugs showed better solubility in Pluronic solutions. The tendency of augmentation in solubility was QCN>CUR>LTG. Results showed better solubilization of drugs in Pluronics which form micelles and have low CMTs. With an objective to enhance the oral bioavailability of drugs, the drug‐loaded Pluronic P123 nanomicelles (PLC for CUR, PLQ for QCN, and PLL for LTG) have been prepared and characterized using UV‐VIS, DLS, SANS, CPT, and TEM measurements. The drug‐loaded P123 nanomicelles having particle sizes range from 18 to 22.5 nm and spherical in shapes. In the in‐vitro release study, CUR and QCN showed slow release,while LTG exhibited a faster release profile. The PLC and PLQ assessed their anti‐oxidant potential had confirmed the oxidation resistance more significantly than the free drug. Considering the pharma uses of CUR, QCN, and LTG drugs and observing the application of Pluronics in drug delivery systems, the present work facilitates insight into the possible formulations of these drugs.
Heterogeneous Carbonylative Sonogashira Reaction Based on Pd/g‐C3N4 Catalyst by Using Formic Acid as the CO Source
Authors: Huo Yong‐Wang , Qi Xinxin , Xu Tiefeng , Lu Wangyang , Wu Xiao‐Feng
Published: July 2021

Alkynones represent one class of interesting building block which are frequently founded in a variety of biologically active compounds.[1] They have been emerged as key intermediates in the synthesis of various natural products and heterocycles.[2] Therefore, a considerable interest has been attracted and numerous strategies have been explored for the synthesis of alkynones. The traditional methods mainly rely on the reactions of acid chlorides with terminal alkynes.>[3–4] However, some drawbacks remain existing, including high reaction temperature, unstable acid chlorides, and poor functional group tolerance.
Facile Synthesis of Porous Hollow Cobalt‐Doped λ‐MnO2 Nano Architectures as a High‐performance Anode Material for Li‐ion Batteries and Li‐ion Hybrid Supercapacitors
Authors: Moon Ji S. , Nulu Arunakumari , Hwang Young G. , Nulu Venugopal , Sohn Keun Y.
Published: July 2021

The cost‐effectiveness and easy availability of MnO2 have attracted researchers′ attention as an anode electrode for LIBs over other transition metal oxides. However, MnO2 usage has been limited to its low reaction reversibility and poor conversion kinetics. Besides, Li‐ion hybrid supercapacitors (LiHSCs) are in urgent demand which offers higher power densities than LIBs without compromising energy density. Among different polymorphs of MnO2, λ‐MnO2, due to its 3D spinel structure, can be applied in many applications. Usually, λ‐MnO2 can be obtained by extracting lithium from LiMn2O4 using complex electrochemical or acid leaching methods. This study presents a modified Li2O2 assisted method to obtain cobalt‐doped 3D architectures of λ‐MnO2 porous hollow nanostructures. The resultant MnxCo1‐xOy hollow structures with 5 % cobalt addition are used as anode for LIBs exhibited excellent charge reversibility and cycle stability over thousands of reaction cycles. This result is known to be one of the finest among MnO2 anodes reported to date. Also, a LiHSC device is fabricated with MnxCo1‐xOy hollow structures as anode and the device exhibits an excellent comprehensive electrochemical performance in terms of high operating voltage (4.2 V), with a specific cell capacity of 33 mAh g−1 at a high current density of 5 A g−1 and achieved the maximum power density of 12261 W kg−1 (with energy density at 81.7 Wh kg−1) with long cycle life.
Self‐Healing Functional Electronic Devices
Authors: Gai Yansong , Li Hu , Li Zhou
Published: July 2021

Electronic devices with various functions bring great convenience and revolutionize the way we live. They are inevitable to degrade over time because of physical or chemical fatigue and damage during practical operation. To make these devices have the ability to autonomously heal from cracks and restore their mechanical and electrical properties, self‐healing materials emerged as the time requires for constructing robust and self‐healing electronic devices. Here the development of self‐healing electronic devices with different functions, for example, energy harvesting, energy storage, sensing, and transmission, is reviewed. The new application scenarios and existing challenges are explored, and possible strategies and perspectives for future practical applications are discussed.
Effect of Nb on Microstructural Evolution and Mechanical Properties of Hot‐Rolled Quenching and Partitioning Steels Containing Bainite
Authors: Chai Zhisong , Hu Jun , Wang Chenchong , Wang Lingyu , Sun Weihua , van der Zwaag Sybrand , Xu Wei
Published: July 2021

Herein, the effect of Nb content on the phase transformation kinetics, microstructure, and mechanical properties of hot‐rolled quenching and partitioning (Q&P) steel is investigated. The characteristics of three C–Mn–Si–Ti steels (0.18C, 2.0Si, 2.6Mn, and 0.015Ti) containing 0, 0.027, or 0.061 wt% Nb are compared. Results reveal that grain boundary pinning by precipitates and Nb solute drag effects refine the austenite grain size during the hot‐rolling process; the microstructural refinement is carried over to the final microstructure subjected to the Q&P treatment. The remaining supersaturated Nb suppresses the bainite formation and decreases the final bainite fraction formed in the Q&P process. The microstructural evolution leads to an increase in the ultimate tensile strength (UTS) of the steel containing 0.027 wt% Nb from 1169 to 1228 MPa, while keeping the total elongation at 18%. When the Nb content is increased to 0.061 wt%, the UTS of the steel increases to 1313 MPa, but the elongation at break drops to 16%. The effect is due to the carbon consumption by the Nb precipitates, which causes a decrease in the stability of the retained austenite and reduces the strain hardening at high strain levels.
Analysis of the Subsurface Volume of Differently Finished AISI 52100 by Cyclic Indentation and X‐Ray Diffraction
Authors: Ostermayer Pascal , Ankener Werner , Blinn Bastian , Smaga Marek , Eifler Dietmar , Beck Tilmann
Published: July 2021

Finishing processes result in changes of near‐surface morphology, which strongly influences the fatigue behavior of components. Especially, roller bearings show a high dependency of the lifetime on surface roughness and the residual stress state in the subsurface volume. To analyze the influence of different finishing processes on the near‐surface morphology, including the residual stress state, roller bearing rings made of AISI 52100 are finished in this work using hard turning, rough grinding, and fine grinding. In addition, fatigue specimens made of AISI 52100 and finished by cryogenic hard turning are investigated. For each condition, the residual stresses are determined at different distances from the surface, showing pronounced compressive stresses for all conditions. While the ground roller bearing rings show highest compressive residual stresses at the surface, the hard turned bearing ring and the cryogenic hard turned fatigue specimens reveal maximum compressive stresses in the subsurface volume. Moreover, cyclic indentation tests (CITs) are conducted in the different subsurface volumes, showing a higher cyclic plasticity in relation to the respective initial state, which is assumed to be caused by finishing‐induced compressive residual stresses. Thus, the presented results indicate a high potential of CITs to efficiently characterize the residual stress state.
Activity Origin and Catalyst Design Principles for Electrocatalytic Oxygen Evolution on Layered Transition Metal Oxide with Halogen Doping
Authors: Zhao Zebi , Chang Haonan , Wang Ruyue , Du Peng , He Xian , Yang Jingkai , Zhang Xinlai , Huang Kai , Fan Dongyu , Wang Yonggang , Pan Xuchao , Lei Ming
Published: July 2021

The electronic structure of transition meatal oxides is in the predominant position among mostly central reactions, such as oxygen electroncatalysis, for the applications in energy storage. Herein, cobalt‐based catalysts are developed by taking the advantage of the strong electronegativity of halogen elements, whose activity and stability are also guaranteed. A “theory–calculation–experiment” research system is proposed to sort out the relationship between the electronegativity of heteroatoms and the electronic structure of layered CoO/F, CoO/Cl, and CoO/Br, for the electrochemical oxygen evolution reaction (OER). Experiments corresponding to calculations also verify that the stronger the electronegativity of the halide ions in the cobalt oxide catalyst, the more obvious the improvement of OER performance. By understanding the electronegative screening of halogen modification, a new perspective on designing principles for water‐splitting devices based on bandgap‐engineered metal oxides is proposed.
Effect of natural rubber latex on the shrinkage behavior and porosity of geopolymer concrete
Authors: Rath Badrinarayan
Published: July 2021

Shrinkage‐reducing admixture has been proved as the best solution to reduce the shrinkage cracks on the surface of the concrete. Various shrinkage‐reducing admixtures available in the local market are chemical, highly hazardous, and limited use in concrete. In the present research, rubber latex was used by replacing water up to 2% in geopolymer concrete. Volumetric shrinkage for geopolymer concrete with different doses of rubber latex was determined and compared those results with traditional cement concrete of the same mix. The relation between volumetric shrinkage and porosity of concrete was studied at a deep level. It was found that a large number of micropores of concrete were reduced by using 2% of rubber latex resulting in decrease in shrinkage significantly. By using rubber latex in concrete, a hazardous expensive chemical shrinkage‐reducing admixture can be replaced by a low‐cost nonhazardous organic substance.
Gender and respiratory conditions: are men at increased risk?
Authors: Bostock Beverley
Published: July 2021

Greater consideration of gender influence may be important not only in diagnosis of respiratory disease, but also for education, engagement and support of men.
Normal form of nilpotent vector field near the tip of the pure spinor cone
Authors: Mikhailov Andrei , Zavaleta Dennis
Published: July 2021

Abstract

Pure spinor formalism implies that supergravity equations in space-time are equivalent to the requirement that the worldsheet sigma-model satisfies certain properties. Here we point out that one of these properties has a particularly transparent geometrical interpretation. Namely, there exists an odd nilpotent vector field on some singular supermanifold, naturally associated to space-time. Is it true that all supergravity fields are encoded in this vector field, as coefficients in its normal form, and the nilpotence is equivalent to the target space equations of motion? We show that this is approximately correct. The normal form is parametrized by some tensor fields, which satisfy hyperbolic equations. These equations are slightly weaker than the full supergravity equations.
Vortex precession and exchange in a Bose-Einstein condensate
Authors: Garaud Julien , Dai Jin , Niemi Antti J.
Published: July 2021

Abstract

Vortices in a Bose-Einstein condensate are modelled as spontaneously symmetry breaking minimum energy solutions of the time dependent Gross-Pitaevskii equation, using the method of constrained optimization. In a non-rotating axially symmetric trap, the core of a single vortex precesses around the trap center and, at the same time, the phase of its wave function shifts at a constant rate. The precession velocity, the speed of phase shift, and the distance between the vortex core and the trap center, depend continuously on the value of the conserved angular momentum that is carried by the entire condensate. In the case of a symmetric pair of identical vortices, the precession engages an emergent gauge field in their relative coordinate, with a flux that is equal to the ratio between the precession and shift velocities.
Assessment of myelination in infants and young children by T1 relaxation time measurements using the magnetization-prepared 2 rapid acquisition gradient echoes sequence
Authors: Kühne Fabienne , Neumann Wolf-Julian , Hofmann Philip , Marques José , Kaindl Angela M. , Tietze Anna
Published: July 2021

Background

Axonal myelination is an important maturation process in the developing brain. Increasing myelin content correlates with the longitudinal relaxation rate (R1=1/T1) in magnetic resonance imaging (MRI).

Objective

By using magnetization-prepared 2 rapid acquisition gradient echoes (MP2RAGE) on a 3-T MRI system, we provide R1 values and myelination rates for infants and young children.

Materials and methods

Average R1 values in white and grey matter regions in 94 children without pathological MRI findings (age range: 3 months to 6 years) were measured and fitted by a saturating-exponential growth model. For comparison, R1 values of 36 children with different brain pathologies are presented. The findings were related to a qualitative evaluation using T2, magnetization-prepared rapid acquisition gradient echo (MP-RAGE) and MP2RAGE.

Results

R1 changes rapidly in the first 16 months of life, then much slower thereafter. R1 is highest in pre-myelinated structures in the youngest subjects, such as the posterior limb of the internal capsule (0.74–0.76±0.04 s−1) and lowest for the corpus callosum (0.37–0.44±0.03 s−1). The myelination rate is fastest in the corpus callosum and slowest in the deep grey matter. R1 is decreased in hypo- and dysmyelination disorders. Myelin maturation is clearly visible on MP2RAGE, especially in the first year of life.

Conclusion

MP2RAGE permits a quantitative R1 mapping method with an examination time of approximately 6 min. The age-dependent R1 values for children without MRI-identified brain pathologies are well described by a saturating-exponential function with time constants depending on the investigated brain region. This model can serve as a reference for this age group and to search for indications of subtle pathologies. Moreover, the MP2RAGE sequence can also be used for the qualitative assessment of myelinated structures.
Analysis of imaging biomarkers and retinal nerve fiber layer thickness in RPGR-associated retinitis pigmentosa
Authors: Birtel Theresa H. , Birtel Johannes , Hess Kristina , Clemens Amelie C. , Lindner Moritz , Herrmann Philipp , Holz Frank G. , Gliem Martin
Published: July 2021

Purpose

To investigate multimodal retinal imaging characteristics including the retinal nerve fiber layer (RNFL) thickness in patients with RPGR-associated retinitis pigmentosa (RP).

Methods

This cross-sectional case–control study included 17 consecutive patients (median age, 21 years) with RPGR-associated RP who underwent retinal imaging including optical coherence tomography (OCT), short-wavelength fundus autofluorescence (AF) imaging, and RNFL scans centered on the optic disc. RNFL thickness was manually segmented and compared to clinical and imaging parameters including the transfoveal ellipsoid zone (EZ) width, the horizontal diameter of the macular hyperautofluorescent ring. RNFL thickness was compared to 17 age- and sex-matched controls.

Results

In patients with RPGR-associated RP, the EZ width (R2 = 0.65), the central hyperautofluorescent ring on AF images (R2 = 0.72), and visual acuity (R2 = 0.68) were negatively correlated with age. In comparison to controls, a significantly (p < 0.0001) increased global RNFL thickness was identified in RPGR-associated RP, which was, however, less pronounced in progressed disease as indicated by the EZ width or the diameter of the central hyperautofluorescent ring.

Conclusions

This study describes retinal characteristics in patients with RPGR-associated RP including a pronounced peripapillary RNFL thickness compared to healthy controls. These results contribute to the knowledge about imaging biomarkers in RP, which might be of interest for therapeutic approaches such as gene replacement therapies.
Comorbidity, cognitive dysfunction, physical functioning, and quality of life in older breast cancer survivors
Authors: Crouch Adele , Champion Victoria L. , Von Ah Diane
Published: July 2021

Purpose

Older breast cancer survivors (BCS) may be at greater risk for cognitive dysfunction and other comorbidities; both of which may be associated with physical and emotional well-being. This study will seek to understand these relationships by examining the association between objective and subjective cognitive dysfunction and physical functioning and quality of life (QoL) and moderated by comorbidities in older BCS.

Methods

A secondary data analysis was conducted on data from 335 BCS (stages I–IIIA) who were ≥ 60 years of age, received chemotherapy, and were 3–8 years post-diagnosis. BCS completed a one-time questionnaire and neuropsychological tests of learning, delayed recall, attention, working memory, and verbal fluency. Descriptive statistics and separate linear regression analyses testing the relationship of each cognitive assessment on physical functioning and QoL controlling for comorbidities were conducted.

Results

BCS were on average 69.79 (SD = 3.34) years old and 5.95 (SD = 1.48) years post-diagnosis. Most were stage II (67.7%) at diagnosis, White (93.4%), had at least some college education (51.6%), and reported on average 3 (SD = 1.81) comorbidities. All 6 physical functioning models were significant (p < .001), with more comorbidities and worse subjective attention identified as significantly related to decreased physical functioning. One model found worse subjective attention was related to poorer QoL (p < .001). Objective cognitive function measures were not significantly related to physical functioning or QoL.

Conclusions

A greater number of comorbidities and poorer subjective attention were related to poorer outcomes and should be integrated into research seeking to determine predictors of physical functioning and QoL in breast cancer survivors.
Data-driven deep density estimation
Authors: Puchert Patrik , Hermosilla Pedro , Ritschel Tobias , Ropinski Timo
Published: July 2021

Density estimation plays a crucial role in many data analysis tasks, as it infers a continuous probability density function (PDF) from discrete samples. Thus, it is used in tasks as diverse as analyzing population data, spatial locations in 2D sensor readings, or reconstructing scenes from 3D scans. In this paper, we introduce a learned, data-driven deep density estimation (DDE) to infer PDFs in an accurate and efficient manner, while being independent of domain dimensionality or sample size. Furthermore, we do not require access to the original PDF during estimation, neither in parametric form, nor as priors, or in the form of many samples. This is enabled by training an unstructured convolutional neural network on an infinite stream of synthetic PDFs, as unbound amounts of synthetic training data generalize better across a deck of natural PDFs than any natural finite training data will do. Thus, we hope that our publicly available DDE method will be beneficial in many areas of data analysis, where continuous models are to be estimated from discrete observations.
A Cross-Sectional Study to Evaluate the Effects of Age and Duration of HIV Infection on Anxiety and Depression in Cisgender Men
Authors: Gianella Sara , Saloner Rowan , Curtin Genevieve , Little Susan J. , Heaton Anne , Montoya Jessica L. , Letendre Scott L. , Marquine María J. , Jeste Dilip V. , Moore David J.
Published: July 2021

This observational cross-sectional study of 152 people with HIV (PWH) examined the effects of age and estimated duration of HIV infection (EDI) on depressive and anxiety symptoms. All participants were cisgender men and completed the Profile of Moods State (POMS), a self-report inventory of current (i.e., past week) mood states. Overall, study results confirmed higher levels of anxiety and depression in PWH compared to individuals without HIV. Age group (< 50 or ≥ 50 years) moderated the effect of EDI (< 3 or ≥ 3 years) on mood disturbance. Specifically, younger PWH with early diagnosed infection exhibited the highest levels of depression and anxiety, whereas depression and anxiety were attenuated in older PWH with early infection such that their POMS scores did not significantly differ from the HIV-negative and chronically HIV-infected groups. Despite the small sample size and other important limitations in our study design, our preliminary findings confirm previous observations that older people may have some adaptive ability to better handle the acute psychological stressors associated with recent HIV infection.
A simple model for desulphurisation of flue gas using reactive filters
Authors: Breward Chris , Kiradjiev Kristian
Published: July 2021

Desulphurisation of flue gas is essential before it can be released safely into the atmosphere. One way of removing sulphur dioxide is to use a purification device incorporating a reactive filter, in which the flue gas stream passes in front of a porous-catalyst-filled structure which converts the gaseous sulphur dioxide into liquid sulphuric acid. In this paper, we build and solve a simple mathematical model to describe the operation of a paradigm reactive filter. Our model captures the transport of sulphur dioxide through the device via advection in the main “outer” flow and diffusion through the catalyst structure along with the production of sulphuric acid. This sulphuric acid gradually accumulates in the filter rendering it less efficient. We determine the clogging time for an individual channel (that is, the time at which the entrance to the channel becomes completely filled with liquid) and explore how the concentrations of sulphur dioxide and oxygen and the thickness of the sulphuric acid layer change as the key dimensionless parameters are varied, comparing numerical and asymptotic results where appropriate. We then turn our attention to the device scale and solve our model numerically to determine the overall lifetime of the device. We vary the key dimensionless parameters and explore how they affect the efficiency of the device. In the physically relevant parameter regime, we find an explicit solution to the outer flow problem which agrees well with numerical solutions and provides a formula for the lifetime of the device. Finally, we propose a formula for determining the catalyst reaction rate, given data on the concentration of sulphur dioxide exiting the device.
Copper ore post-flotation settling tanks in Poland: social acceptance or objection?
Authors: Pactwa Katarzyna , Górniak-Zimroz Justyna
Published: July 2021

The issues concerning mining have been causing a wide variety of emotions. Objection to and disagreement with new investments, but also social acceptance for the operation of mining plants offering stable employment. Production in this sector is associated with the generation of waste. In the case of copper ore mining, the result of the entrepreneur's activity consists of waste treatment facilities in the form of post-flotation settling tanks. In addition to the inactive facilities in Lower Silesia, there is also the settling tank Zelazny Most, which is used and expanded. The large area and risk to the environment allow to suppose that the existence of settling tanks in social space generates conflicts or it is conducive to the emigration of the residents. In order to verify the above-mentioned hypothesis, the authors used geographic information systems to analyse the current population status and expansion of the road and rail network, the residents’ drinking water sources and soil permeability in five impact zones. The achieved results allow to conclude that the facilities belonging to KGHM PM S.A. coexist with their surroundings, thus gaining social acceptance. The proposed research methodology can be used by the entrepreneurs, but also local authorities to evaluate the acceptance of mining waste disposal facilities.
The place of vericiguat in the landscape of treatment for heart failure with reduced ejection fraction
Authors: Aimo Alberto , Castiglione Vincenzo , Vergaro Giuseppe , Panichella Giorgia , Senni Michele , Lombardi Carlo Mario , Emdin Michele
Published: July 2021

The significant morbidity and mortality associated with heart failure with reduced (HFrEF) or preserved ejection fraction (HFpEF) justify the search for novel therapeutic agents. The nitric oxide (NO)–soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway plays an important role in the regulation of cardiovascular function. This pathway is disrupted in HF resulting in decreased protection against myocardial injury. The sGC activator cinaciguat increases cGMP levels by direct, NO-independent activation of sGC, and may be particularly effective in conditions of increased oxidative stress and endothelial dysfunction, and then reduced NO levels, but this comes at the expense of a greater risk of hypotension. Conversely, sGC stimulators (riociguat and vericiguat) enhance sGC sensitivity to endogenous NO, and then exert a more physiological action. The phase 3 VICTORIA trial found that vericiguat is safe and effective in patients with HFrEF and recent HF decompensation. Therefore, adding vericiguat may be considered in individual patients with HFrEF, particularly those at higher risk of HF hospitalization; the efficacy of the sacubitril/valsartan-vericiguat combination in HFrEF is currently unknown.
The application of a phycocyanin extract obtained from Arthrospira platensis as a blue natural colorant in beverages
Authors: García Ana Belén , Longo Eleonora , Bermejo Ruperto
Published: July 2021

Currently, the food additive industry has interest in replacing artificial dyes with natural pigments, trying to maintain consumer interest and increase their awareness towards healthy diets. Phycobiliproteins are light-harvesting and water-soluble proteins extracted from cyanobacteria and red algae that can be employed as natural additives. In the present work, a C-phycocyanin extract from the cyanobacterium Arthrospira platensis was tested as blue colorant in beverages to demonstrate that samples containing the protein extract have a color similar to marketed beverages containing synthetic dyes. Using spectroscopy and colorimetry, the extract was characterized and gave evidence of having good properties and good stability in the pH range between 3.0 and 9.0. The staining factors, representing the amount of blue protein needed to reproduce the color of bluish commercial samples, ranged between 15.6 and 111.7 mg·L−1, being sufficiently low in all samples. Additionally, color stability during a short period of cold storage was studied: it demonstrated that isotonic and tonic beverages remained stable throughout the 11-days analysis period with no significant changes. These results prove that the C-phycocyanin extract has potential applications in food as natural colorant, being an alternative option to synthetic coloring molecules.
Scheduling with gaps: new models and algorithms
Authors: Chrobak Marek , Golin Mordecai , Lam Tak-Wah , Nogneng Dorian
Published: July 2021

We consider scheduling problems for unit jobs with release times, where the number or size of the gaps in the schedule is taken into consideration, either in the objective function or as a constraint. Except for several papers on minimum-energy scheduling, there is no work in the scheduling literature that uses performance metrics depending on the gap structure of a schedule. One of our objectives is to initiate the study of such scheduling problems. We focus on the model with unit-length jobs. First we examine scheduling problems with deadlines, where we consider two variants of minimum-gap scheduling: maximizing throughput with a budget for the number of gaps and minimizing the number of gaps with a throughput requirement. We then turn to other objective functions. For example, in some scenarios gaps in a schedule may be actually desirable, leading to the problem of maximizing the number of gaps. A related problem involves minimizing the maximum gap size. The second part of the paper examines the model without deadlines, where we focus on the tradeoff between the number of gaps and the total or maximum flow time. For all these problems we provide polynomial time algorithms, with running times ranging from $$O(n\log n)$$

O
(
n
log
n
)

for some problems to $$O(n^7)$$

O
(

n
7

)

for other. The solutions involve a spectrum of algorithmic techniques, including different dynamic programming formulations, speed-up techniques based on searching Monge arrays, searching $$X+Y$$

X
+
Y

matrices, or implicit binary search. Throughout the paper, we also draw a connection between gap scheduling problems and their continuous analogues, namely hitting set problems for intervals of real numbers. As it turns out, for some problems the continuous variants provide insights leading to efficient algorithms for the corresponding discrete versions, while for other problems completely new techniques are needed to solve the discrete version.
Clinoptilolite as a natural, active zeolite catalyst for the chemical transformations of geraniol
Authors: Fajdek-Bieda Anna , Wróblewska Agnieszka , Miądlicki Piotr , Tołpa Jadwiga , Michalkiewicz Beata
Published: July 2021

This work presented the studies with the natural zeolite—clinoptilolite as the catalyst for the isomerization of geraniol. During the research, it turned out that the studied process is much more complicated, and not only isomerization takes place in it, but also dehydration, oxidation, dimerization, cyclization and fragmentation of the carbon chain. Geraniol is an organic raw material which can be obtained not only by a chemical synthesis but also from plants (renewable biomass) by distillation or extraction method, for example a source of geraniol can be a plant—geranium. Before catalytic tests clinoptilolite was characterized by the instrumental methods, such as: XRD, porosity studies—nitrogen adsorption at 77 K, SEM, EDXRF, and FT-IR. Gas chromatography analyses showed that the main products of geraniol isomerization process were 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol. The selectivity of 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol depended on the temperature, catalyst content and reaction time. These parameters were changed in the following ranges: 80–150 °C (temperature), 5–15 wt% (catalyst content) and 15–1440 min. (reaction time). The most favorable conditions for 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol obtaining were: temperature 140 ºC, catalyst content 12.5 wt% and reaction time 180 min. At these conditions, the conversion of geraniol amounted to 98 mol%, and the selectivities of 6,11-dimethyl-2,6,10-dodecatrien-1-ol and thumbergol amounted to 14 and 47 mol%, respectively.
Beliefs on Sexual Violence in the Context of System Justification Theory: The Role of Hostile Sexism and Beliefs in Biological Origins of Gender Differences
Authors: Łyś Agnieszka E. , Studzińska Anna , Bargiel-Matusiewicz Kamilla
Published: July 2021

Estimates suggest that around 20% of women may have experienced rape. Various misconceptions about rape (i.e., rape myths) are closely related to victim blaming. In our studies we tested the link between system justification, beliefs in biological origins of gender differences, ambivalent sexism and beliefs concerning sexual violence. Study 1 was conducted among 433 Polish students. The sequential mediation analysis suggests that system justification predicts the level of rape myth acceptance through beliefs in biological origins of gender differences and then hostile (but not benevolent) sexism. In Study 2, conducted among 197 Polish students, we tested the relationship between beliefs in biological origins of gender differences and beliefs concerning sexual violence using experimental design. Contrary to our expectations, students who read the text about social origins of gender differences perceived the survivor of a hypothetical acquaintance rape as less credible, and proposed a lower sentence for a stranger rape perpetrator, compared to participants who read about biological origins of gender differences. We suspect that this is due to experiencing reactance when confronted with social explanations of gender differences. We discuss implications for research and policy.
Silver-Derived Antimicrobial Coatings for the Prevention of Microbial Biofilms in Metal Pipes
Authors: Vela-Cano M. , Garcia-Fontana C. , Osorio F. , González-Martinez A. , González-López J.
Published: July 2021

Biodeterioration is one of the most important processes in metal pipeline corrosion, and it can be due to physical, chemical, and biological factors. Coatings rich in silver have been used to inhibit this undesirable phenomenon. In this study, the antimicrobial properties of several silver-containing products used as a coating in pipelines were determined on a pilot scale in order to evaluate the ability of silver to inhibit biofilm formation. The results showed that the coating with silver zeolite at a concentration of 2000 mg L–1 inhibited the formation of a microbial biofilm and prevented the biodeterioration process. Therefore, from our study, it can be concluded that silver zeolite shows greater protection capacity than other silver preparations and presents advantages in relation to other silver coatings that are currently available