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1.
Chem Sci ; 15(24): 9054-9086, 2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38903216

RESUMEN

At the energy-chemistry nexus, key molecules include carbon dioxide (CO2), hydrogen (H2), methane (CH4), and ammonia (NH3). The position of these four molecules and that of the more general family of synthetic macromolecular polymer blends (found in plastics) were cross-analyzed with the planetary boundary framework, and as part of five scientific policy roadmaps for the energy transition. According to the scenarios considered, the use of some of these molecular substances will be drastically modified in the coming years. Ammonia, which is currently almost exclusively synthesized as feedstock for the fertilizer industry, is envisioned as a future carbon-free energy vector. "Green hydrogen" is central to many projected decarbonized chemical processes. Carbon dioxide is forecast to shift from an unavoidable byproduct to a valuable feedstock for the production of carbon-based compounds. In this context, we believe that interdisciplinary elements from history, economics and anthropology are relevant to any attempted cross-analysis. Distinctive and crucial insights drawn from elements of humanities and social sciences have led us to formulate or re-raise open questions and possible blind-spots in main roadmaps, which were developed to guide, inter alia, chemical research toward the energy transition. We consider that these open questions are not sufficiently addressed in the academic arena around chemical research. Nevertheless, they are relevant to our understanding of the current planetary crisis, and to our capacity to properly assess the potential and limitations of chemical research addressing it. This academic perspective was written to share this understanding with the broader academic community. This work is intended not only as a call for a larger interdisciplinary method, to develop a sounder scientific approach to broader scenarios, but also - and perhaps mostly - as a call for the development of radically transdisciplinary routes of research. As scientists with different backgrounds, specialized in different disciplines and actively involved in contributing to shape solutions by means of our research, we bear ethical responsibility for the consequences of our acts, which often lead to consequences well beyond our discipline. Do our research and the knowledge it produces respond, perpetuate or even aggravate the problems encountered by society?

2.
Eur J Investig Health Psychol Educ ; 12(6): 516-533, 2022 May 25.
Artículo en Inglés | MEDLINE | ID: mdl-35735459

RESUMEN

This article discusses possible challenges and potentials in the use of digital geomedia in the context of written and oral argumentation in higher education by examining the perspectives of students and lecturers, especially for the subjects of geography in general and primary school science. To this end, potentials and challenges, as well as competences that have to be promoted among pupils and students in dealing with digital geomedia in the context of written and oral argumentation are first discussed. In the following, we present the results of a mixed methods approach in which we surveyed student teachers with a questionnaire (n = 150) on the one hand and, on the other hand, reflected their view of the issue by analysing qualitative expert interviews (n = 17) with lecturers who teach at the same universities in the corresponding degree programmes. In this way we contextualise the student's self-assessment in the respective location's teacher training. Our results show that there is a high degree of commonality between lecturers and students with regard to the importance of argumentation with digital geomedia. At the same time, the assessment of the students' abilities differs greatly; most students feel capable of dealing with these topics, while lecturers see deficits here.

3.
Gerontology ; 66(1): 15-23, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31266038

RESUMEN

BACKGROUND: Associations between lower limb muscle strength and balance performance in adults have previously been reported. However, the function of the foot muscles for postural control has not been understood, yet. OBJECTIVE: The purpose of the present study was to investigate associations between pronator and supinator muscle strength, subtalar range of motion (ROM) and postural stability while standing under various conditions in young versus old adults. METHODS: Using a custom-built apparatus equipped with a force transducer and an electrogoniometer, maximum voluntary isometric subtalar pronator and supinator strength as well as ROM tests were administered to 30 young (mean age: 25.1 years) and 30 old (mean age: 65.2 years) volunteers. Total active subtalar ROM, peak pronator and peak supinator torques were measured. While standing on a force plate, limits of stability (LOS) were determined during anterior-posterior (AP) and medio-lateral (ML) leaning tasks. Furthermore, sway distance and velocity during single-legged standing were measured. Correlation and regression analyses were conducted. RESULTS: In both age groups, subtalar pronator muscle strength was related to AP-LOS (young: r = 0.36; old: r = 0.49). In young adults, subtalar supinator muscle strength was associated with ML-LOS (r = 0.41). The regression analyses revealed that summed subtalar muscle strength predicts 13 and 20% of the variance of AP-LOS in young and old adults, respectively. Summed subtalar muscle strength was found to predict 18% of the variance in ML-LOS in young but not in old adults. There were no correlations and no predictors found concerning subtalar muscle strength and postural sway during single-legged standing for both age groups. CONCLUSIONS: Longitudinal studies have to proof whether pronator muscle strength training might positively affect balance performance during AP leaning, specifically in old adults.


Asunto(s)
Articulación Talocalcánea/fisiología , Adulto , Anciano , Femenino , Humanos , Extremidad Inferior/fisiología , Masculino , Persona de Mediana Edad , Fuerza Muscular , Músculo Esquelético/fisiología , Equilibrio Postural/fisiología , Rango del Movimiento Articular/fisiología
4.
Dalton Trans ; 48(18): 6071-6082, 2019 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-30758389

RESUMEN

Non-toxic, highly active and robust complexes are the holy grail as ideal green catalysts for the polymerisation of biorenewable and biodegradable polylactide. Four new zinc guanidine complexes [ZnCl2(TMG4NMe2asme)], [ZnCl2(TMG5Clasme)], [ZnCl2(TMG5Measme)] and [ZnCl2(TMG5NMe2asme)] with different electron-donating and electron-withdrawing groups on the ligand's aromatic backbone have been synthesised. Ligands are derived from low-cost commercially available compounds and have been converted by a three- or four-step synthesis process into the desired ligand in good yields. The compounds have been fully characterised and tested in the ROP of rac-LA under industrially relevant conditions. The complexes are based on the recently published structure [ZnCl2(TMGasme)] which has shown high activity in the polymerisation of lactide at 150 °C. Different substituents in the para-position of the guanidine moiety significantly increase the polymerisation rate whereas positioning substituents in the meta-position causes no change in the reaction rate. With molecular weights over 71 000 g mol-1 being achievable, the best system produces polymers for multiple industrial applications and its polymerisation rate approaches that of Sn(Oct)2. The robust systems are able to polymerise non-purified lactide. The initiation of the polymerisation is suggested to occur due to impurities in the monomer.

5.
Phys Chem Chem Phys ; 20(10): 6891-6904, 2018 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-29460932

RESUMEN

To determine the preferred water molecule binding sites of the polybasic sulfa drugs sulfamethoxazole (SMX) and sulfisoxazole (SIX), we have studied their monomers and monohydrated complexes through laser-desorption conformer-specific UV and IR spectroscopy. Both the SMX and SIX monomer adopt a single conformer in the molecular beam. On the basis of their conformer-specific IR spectra in the NH stretch region, these conformers were assigned to the SMX and SIX global minimum structures, both exhibiting a staggered sulfonamide group and an intramolecular C-HO[double bond, length as m-dash]S hydrogen bond. The SMX-H2O and SIX-H2O complexes each adopt a single isomer in the molecular beam. Their isomeric structures were determined based on their isomer-specific IR spectra in the NH/OH stretch region. Quantum Theory of Atoms in Molecules analysis of the calculated electron densities revealed that in the SMX-H2O complex the water molecule donates an O-HN hydrogen bond to the heterocycle nitrogen atom and accepts an N-HO hydrogen bond from the sulfonamide NH group. In the SIX-H2O complex, however, the water molecule does not bind to the heterocycle but instead donates an O-HO[double bond, length as m-dash]S hydrogen bond to the sulfonamide group and accepts an N-HO hydrogen bond from the sulfonamide NH group. Both water complexes are additionally stabilized by a Cph-HOH2 hydrogen bond. Interacting Quantum Atoms analysis suggests that all intermolecular hydrogen bonds are dominated by the short-range exchange-correlation contribution.


Asunto(s)
Antiinfecciosos/química , Sulfametoxazol/química , Sulfisoxazol/química , Agua/química , Sitios de Unión , Fenómenos Biofísicos , Humanos , Enlace de Hidrógeno , Luz , Modelos Moleculares , Estructura Molecular , Teoría Cuántica , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Relación Estructura-Actividad , Sulfanilamida/química
6.
Phys Chem Chem Phys ; 19(22): 14625-14640, 2017 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-28537284

RESUMEN

We have studied the conformational preferences of the sulfonamide drug sulfanilamide, its dimer, and its monohydrated complex through laser desorption single-conformation UV and IR spectroscopy in a molecular beam. Based on potential energy curves for the inversion of the anilinic and the sulfonamide NH2 groups calculated at DFT level, we suggest that the zero-point level wave function of the sulfanilamide monomer is appreciably delocalized over all four conformer wells. The sulfanilamide dimer, and the monohydrated complex each exhibit a single isomer in the molecular beam. The isomeric structures of the sulfanilamide dimer and the monohydrated sulfanilamide complex were assigned based on their conformer-specific IR spectra in the NH and OH stretch region. Quantum Theory of Atoms in Molecules (QTAIM) analysis of the calculated electron density in the water complex suggests that the water molecule is bound side-on in a hydrogen bonding pocket, donating one O-HO[double bond, length as m-dash]S hydrogen bond and accepting two hydrogen bonds, a NHO and a CHO hydrogen bond. QTAIM analysis of the dimer electron density suggests that the Ci symmetry dimer structure exhibits two dominating N-HO[double bond, length as m-dash]S hydrogen bonds, and three weaker types of interactions: two CHO bonds, two CHN bonds, and a chalcogen OO interaction. Most interestingly, the molecular beam dimer structure closely resembles the R dimer unit - the dimer unit with the greatest interaction energy - of the α, γ, and δ crystal polymorphs. Interacting Quantum Atoms analysis provides evidence that the total intermolecular interaction in the dimer is dominated by the short-range exchange-correlation contribution.


Asunto(s)
Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Sulfanilamidas/química , Enlace de Hidrógeno , Isomerismo , Rayos Láser , Conformación Molecular , Teoría Cuántica , Sulfanilamida
7.
J Foot Ankle Res ; 8: 64, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26609327

RESUMEN

BACKGROUND: The angle-dependent torque capacity of the subtalar pronators and supinators is important to maintain dynamic ankle stabilisation. Based on the peak torques during maximum voluntary isometric pronation and supination across the subtalar range of motion, the strength curves of younger and elderly males and females were investigated. METHODS: Maximum voluntary isometric subtalar pronator and supinator strength tests were administered to 30 younger and 30 elderly volunteers (each 15 male and 15 female subjects). Total active subtalar range of motion and peak pronator and supinator torques were measured in five anatomical subtalar joint angles using a custom-built apparatus with two force transducers. Furthermore, relative torques (normalised to the individual peak torque) and pronator-to-supinator strength-ratios were also calculated. RESULTS: Pronator-to-supinator strength ratio, and peak pronator and supinator torques are affected by age and by joint angle x age interactions. All supinator strength curves show a steadily descending characteristic from the pronated to the supinated positions. The pronator strength curve had an inverted U-shaped characteristic, except for younger women of whom 47 % exert highest peak values in the end-range pronation angle. Both relative pronator and supinator strength are dependent on sex (P < 0.05). Relative pronator strength is also affected by joint angle x sex (P < 0.0001) and joint angle x sex x age (P < 0.05) interactions. Beside age effects on all range of motion parameters, pronation range of motion is influenced by a sex x age interaction (P < 0.05). CONCLUSIONS: Age- and sex-related differences in both subtalar strength profile and range of motion have to be considered when testing strength across subtalar range of motion. Younger females have higher pronator strength capacity in the most pronated joint angle, which may be due in part to their greater subtalar joint range of motion compared to the other groups. In the most supinated position both pronator and supinator strength capacity is reduced in younger females compared to younger males.

8.
Dig Liver Dis ; 43(10): 788-91, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21676663

RESUMEN

AIM: Prospective evaluation of the new 0.025 in. Visiglide(®) guidewire to facilitate endoscopic retrograde cholangiopancreaticography using the Olympus V-scope. MATERIALS AND METHODS: Interventional endoscopic retrograde cholangiopancreaticography was performed in 9 patients with the Olympus V-scope and the 0.025 in. Visiglide(®) guidewire (VS group), whilst 9 other patients underwent endoscopic retrograde cholangiopancreaticography with a conventional Olympus duodenoscope using 0.035 in. conventional guidewires (controls). Exchange time of accessories, X-ray time, dose and endoscopic retrograde cholangiopancreaticography examination time were investigated. RESULTS: The VS group showed a significantly lower exchange time of endoscopic retrograde cholangiopancreaticography accessories (9; 4-10s, p<0.0001) than controls (29; 19-44s). The Visiglide(®) guidewire was complete fixable by the elevator in 35/36 instrument exchanges (97%) compared to 16/31 exchanges (52%) using conventional guidewires. LIMITATIONS: Single-centre study, small patient numbers, two investigators. CONCLUSIONS: Endoscopic retrograde cholangiopancreaticography using the Olympus V-scope with the new 0.025 in. Visiglide(®) guidewire enables a 3-fold faster exchange of accessories due to a nearly complete fixation of the guidewire.


Asunto(s)
Colangiopancreatografia Retrógrada Endoscópica/instrumentación , Duodenoscopios , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Estadísticas no Paramétricas , Factores de Tiempo , Adulto Joven
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