Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 54
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Appl Crystallogr ; 57(Pt 1): 181-186, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38322722

RESUMO

The growing pressure on school curricula has meant crystals and the science of crystallography have been cut from or made optional for many educational programs. This omission is a serious disservice to the history and understanding of modern sciences, given that crystallography underpins many of the greatest advancements in science over the past century, is a critical component of many modern research papers and patents, and has 29 Nobel Prizes awarded in the field. This contribution describes a simple activity to target classroom and public engagement with crystallography, using marshmallows or equivalent sweets/candy to represent atoms and cocktail sticks to represent bonds, together with examples of how crystals are studied and how they are useful. Though it has a simple basis, this activity can be extended in numerous ways to reflect the aims of the demonstrator, and a few of these are described.

2.
Analyst ; 148(18): 4373-4385, 2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37594446

RESUMO

Optimal oncological results and patient outcomes are achieved in surgery for early breast cancer with breast conserving surgery (BCS) where this is appropriate. A limitation of BCS occurs when cancer is present at, or close, to the resection margin - termed a 'positive' margin - and re-excision is recommended to reduce recurrence rate. This is occurs in 17% of BCS in the UK and there is therefore a critical need for a way to assess margin status intraoperatively to ensure complete excision with adequate margins at the first operation. This study presents the potential of high wavenumber (HWN) Raman spectroscopy to address this. Freshly excised specimens from thirty patients undergoing surgery for breast cancer were measured using a surface Raman probe, and a multivariate classification model to predict normal versus tumour was developed from the data. This model achieved 77.1% sensitivity and 90.8% specificity following leave one patient out cross validation, with the defining features being differences in water content and lipid versus protein content. This demonstrates the feasibility of HWN Raman spectroscopy to facilitate future intraoperative margin assessment at specific locations. Clinical utility of the approach will require further research.


Assuntos
Neoplasias da Mama , Neoplasias Mamárias Animais , Humanos , Animais , Feminino , Análise Espectral Raman , Neoplasias da Mama/cirurgia , Margens de Excisão , Sorogrupo
3.
Phys Chem Chem Phys ; 25(35): 23637-23644, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37650575

RESUMO

Mechanochemistry has proven to be a highly effective method for the synthesis of organic compounds. We studied the kinetics of the catalyst-free Knoevenagel reaction between 4-nitrobenzaldehyde and malononitrile, activated and driven by ball milling. The reaction was investigated in the absence of solvents (neat grinding) and in the presence of solvents with different polarities (liquid-assisted grinding). The reaction was monitored using time-resolved in situ Raman spectroscopy and powder X-ray diffraction (PXRD). Our results indicate a direct relationship between solvent polarity and reaction kinetics, with higher solvent polarity leading to faster product (2-(4-nitrobenzylidone)malononitrile) formation. For the first time, we were able to isolate and determine the structure of an intermediate 2-(hydroxy(4-nitrophenyl)methyl)malononitrile based on PXRD data.

4.
BMJ Open ; 13(5): e070169, 2023 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-37156575

RESUMO

INTRODUCTION: Improving healthy lifestyles of adolescents is challenging. Citizen Science is a way to engage them in the design and delivery of interventions, and may also increase their interest in science, technology, engineering and mathematics (STEM). The Science Engagement to Empower aDolescentS (SEEDS) project aims to use an equity-lens, and engage and empower boys and girls from deprived areas by designing and cocreating interventions to promote healthy lifestyles, and to seed interest in STEM. METHODS AND ANALYSIS: SEEDS is a cluster randomised controlled trial in four countries (Greece, the Netherlands, Spain and the UK). Each country will recruit six to eight high schools from lower socioeconomic neighbourhoods. Adolescents aged 13-15 years are the target population. High schools will be randomised into intervention or control group. Each country will select 15 adolescents from intervention schools called ambassadors, who will be involved throughout the project.In each country, focus groups with ambassadors and stakeholders will focus on physical activity, snacking behaviour and STEM. The input from focus groups will be used to shape Makeathon events, cocreation events where adolescents and stakeholders will develop the interventions. The resultant intervention will be implemented in the intervention schools during 6 months. In total, we aim to recruit 720 adolescents who will complete questionnaires related to healthy lifestyles and STEM outcomes at baseline (November 2021) and after the 6 months (June 2022). ETHICS AND DISSEMINATION: The four countries obtained approval from their corresponding Ethics Committees (Greece: Bioethics Committee of Harokopio University; the Netherlands: The Medical Research Ethics Committee of the Erasmus Medical Center; Spain: The Drug Research Ethics Committee of the Pere Virgili Health Research Institute; UK: Sport and Health Sciences Ethics Committee of the University of Exeter). Informed consent will be collected from adolescents and their parents in line with General Data Protection Regulation legislation. The findings will be disseminated by conference presentations, publications in scientific peer-reviewed journals and during (local) stakeholders and public events. Lessons learnt and the main results will also be used to provide policy recommendations. TRIAL REGISTRATION NUMBER: NCT05002049.


Assuntos
Ciência do Cidadão , Esportes , Masculino , Feminino , Humanos , Adolescente , Promoção da Saúde/métodos , Exercício Físico , Estilo de Vida Saudável , Ensaios Clínicos Controlados Aleatórios como Assunto
5.
Chem Mater ; 35(4): 1514-1526, 2023 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-36873624

RESUMO

The syntheses of Ni-poor (NCM111, LiNi1/3Co1/3Mn1/3O2) and Ni-rich (NCM811 LiNi0.8Co0.1Mn0.1O2) lithium transition-metal oxides (space group R3̅m) from hydroxide precursors (Ni1/3Co1/3Mn1/3(OH)2, Ni0.8Co0.1Mn0.1(OH)2) are investigated using in situ synchrotron powder diffraction and near-edge X-ray absorption fine structure spectroscopy. The development of the layered structure of these two cathode materials proceeds via two utterly different reaction mechanisms. While the synthesis of NCM811 involves a rock salt-type intermediate phase, NCM111 reveals a layered structure throughout the entire synthesis. Moreover, the necessity and the impact of a preannealing step and a high-temperature holding step are discussed.

6.
J Exp Child Psychol ; 232: 105669, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-36996749

RESUMO

Interpersonal synchrony (IPS) is the temporal coordination of behavior during social interactions. IPS acts as a social cue signifying affiliation both when children witness IPS between others and when they experience it themselves. However, it is unclear which temporal qualities of IPS produce these effects and why. We hypothesized that both the simultaneity and temporal regularity of partners' actions would influence affiliation judgments and that subjective perceptions of IPS ("togetherness") would play a role in mediating these relations. In two online tasks, children aged 4 to 11 years listened to a pair of children tapping (witnessed IPS; n = 68) or themselves tapped with another child (experienced IPS; n = 63). Tapping partners were presented as real, but the sounds attributed to them were computer generated so that their temporal relations could be experimentally manipulated. The simultaneity and regularity of their tapping was systematically manipulated across trials. For witnessed IPS, both the simultaneity and regularity of partners' tapping significantly positively affected the perceived degree of affiliation between them. These effects were mediated by the perceived togetherness of the tapping. No affiliative effects of IPS were found in the experienced IPS condition. Our findings suggest that both the simultaneity and regularity of partners' actions influence children's affiliation judgments when witnessing IPS via elicited perceptions of togetherness. We conclude that temporal interdependence-which includes but is not limited to simultaneity of action-is responsible for inducing perceptions of affiliation during witnessed IPS.


Assuntos
Percepção Auditiva , Comportamento Social , Humanos , Criança , Computadores , Relações Interpessoais
7.
Phys Chem Chem Phys ; 24(46): 28444-28456, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36399064

RESUMO

X-ray characterisation methods have undoubtedly enabled cutting-edge advances in all aspects of materials research. Despite the enormous breadth of information that can be extracted from these techniques, the challenge of radiation-induced sample change and damage remains prevalent. This is largely due to the emergence of modern, high-intensity X-ray source technologies and the growing potential to carry out more complex, longer duration in situ or in operando studies. The tunability of synchrotron beamlines enables the routine application of photon energy-dependent experiments. This work explores the structural stability of [Rh(COD)Cl]2, a widely used catalyst and precursor in the chemical industry, across a range of beamline parameters that target X-ray energies of 8 keV, 15 keV, 18 keV and 25 keV, on a powder X-ray diffraction synchrotron beamline at room temperature. Structural changes are discussed with respect to absorbed X-ray dose at each experimental setting associated with the respective photon energy. In addition, the X-ray radiation hardness of the catalyst is discussed, by utilising the diffraction data collected at the different energies to determine a dose limit, which is often considered in protein crystallography and typically overlooked in small molecule crystallography. This work not only gives fundamental insight into how damage manifests in this organometallic catalyst, but will encourage careful consideration of experimental X-ray parameters before conducting diffraction on similar radiation-sensitive organometallic materials.


Assuntos
Fótons , Síncrotrons , Raios X , Cristalografia , Difração de Raios X
8.
Wellcome Open Res ; 7: 176, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36324703

RESUMO

The Global Infectious Disease Ethics (GLIDE) Collaborative is launching a new Wellcome Open Research (WOR) Gateway, and we as the leaders of GLIDE hope to encourage submissions to this timely and necessary new platform for publishing open access peer-reviewed articles focusing on this area.

9.
Front Psychol ; 13: 897015, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35734455

RESUMO

Interpersonal synchrony - the tendency for social partners to temporally co-ordinate their behaviour when interacting - is a ubiquitous feature of social interactions. Synchronous interactions play a key role in development, and promote social bonding and a range of pro-social behavioural outcomes across the lifespan. The process of achieving and maintaining interpersonal synchrony is highly complex, with inputs required from across perceptual, temporal, motor, and socio-cognitive domains. In this conceptual analysis, we synthesise evidence from across these domains to establish the key components underpinning successful non-verbal interpersonal synchrony, how such processes interact, and factors that may moderate their operation. We also consider emerging evidence that interpersonal synchrony is reduced in autistic populations. We use our account of the components contributing to interpersonal synchrony in the typical population to identify potential points of divergence in interpersonal synchrony in autism. The relationship between interpersonal synchrony and broader aspects of social communication in autism are also considered, together with implications for future research.

10.
Nat Chem ; 14(5): 584, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35513569

Assuntos
Benzeno
11.
Mater Horiz ; 8(5): 1446-1453, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34846452

RESUMO

Cadmium cyanide, Cd(CN)2, is a flexible coordination polymer best studied for its strong and isotropic negative thermal expansion (NTE) effect. Here we show that this NTE is actually X-ray-exposure dependent: Cd(CN)2 contracts not only on heating but also on irradiation by X-rays. This behaviour contrasts that observed in other beam-sensitive materials, for which X-ray exposure drives lattice expansion. We call this effect 'negative X-ray expansion' (NXE) and suggest its origin involves an interaction between X-rays and cyanide 'flips'; in particular, we rule out local heating as a possible mechanism. Irradiation also affects the nature of a low-temperature phase transition. Our analysis resolves discrepancies in NTE coefficients reported previously on the basis of X-ray diffraction measurements, and we establish the 'true' NTE behaviour of Cd(CN)2 across the temperature range 150-750 K. The interplay between irradiation and mechanical response in Cd(CN)2 highlights the potential for exploiting X-ray exposure in the design of functional materials.

12.
J Phys Chem A ; 125(34): 7473-7488, 2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34420303

RESUMO

X-ray characterization techniques are invaluable for probing material characteristics and properties, and have been instrumental in discoveries across materials research. However, there is a current lack of understanding of how X-ray-induced effects manifest in small molecular crystals. This is of particular concern as new X-ray sources with ever-increasing brilliance are developed. In this paper, systematic studies of X-ray-matter interactions are reported on two industrially important catalysts, [Ir(COD)Cl]2 and [Rh(COD)Cl]2, exposed to radiation in X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) experiments. From these complementary techniques, changes to structure, chemical environments, and electronic structure are observed as a function of X-ray exposure, allowing comparisons of stability to be made between the two catalysts. Radiation dose is estimated using recent developments to the RADDOSE-3D software for small molecules and applied to powder XRD and XPS experiments. Further insights into the electronic structure of the catalysts and changes occurring as a result of the irradiation are drawn from density functional theory (DFT). The techniques combined here offer much needed insight into the X-ray-induced effects in transition-metal catalysts and, consequently, their intrinsic stabilities. There is enormous potential to extend the application of these methods to other small molecular systems of scientific or industrial relevance.

13.
Cryst Growth Des ; 21(5): 3047-3055, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-34267598

RESUMO

Mechanochemical synthesis has recently emerged as a scalable "green" approach for the preparation of MOFs, but current understanding of the underlying reaction mechanisms is limited. In this work, an investigation of the reaction pathway of the mechanochemical synthesis of MOF-74 from ZnO and 2,5-dihydroxyterephthalic acid (H4HDTA), using DMF as a liquid additive, is presented. The complex reaction pathway involves the formation of four short-lived intermediate phases, prior to the crystallization of MOF-74. The crystal structures of three of these intermediates have been determined using a combination of single-crystal and powder X-ray diffraction methods and are described here. The initial stages of the reaction are very fast, with a DMF solvate of H4HDTA forming after only 2 min of milling. This is followed by crystallization, after only 4 min of milling, of a triclinic one-dimensional coordination polymer, Zn(H2DHTA)(DMF)2(H2O)2, which converts into a monoclinic polymorph on additional milling. Highly crystalline MOF-74 appears after prolonged milling, for at least 70 min.

14.
Chemistry ; 27(51): 13029-13039, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34213033

RESUMO

The flexibility of the zeolite Rho framework offers great potential for tunable molecular sieving. The fully copper-exchanged form of Rho and mixed Cu,H- and Cu,Na-forms have been prepared. EPR spectroscopy reveals that Cu2+ ions are present in the dehydrated forms and Rietveld refinement shows these prefer S6R sites, away from the d8r windows that control diffusion. Fully exchanged Cu-Rho remains in an open form upon dehydration, the d8r windows remain nearly circular and the occupancy of window sites is low, so that it adsorbs CO2 rapidly at room temperature. Breakthrough tests with 10 % CO2 /40 % CH4 mixtures show that Cu4.9 -Rho is able to produce pure methane, albeit with a relatively low capacity at this pCO2 due to the weak interaction of CO2 with Cu cations. This is in strong contrast to Na-Rho, where cations in narrow elliptical window sites enable CO2 to be adsorbed with high selectivity and uptake but too slowly to enable the production of pure methane in similar breakthrough experiments. A series of Cu,Na-Rho materials was prepared to improve uptake and selectivity compared to Cu-Rho, and kinetics compared to Na-Rho. Remarkably, Cu,Na-Rho with >2 Cu cations per unit cell exhibited exsolution, due to the preference of Na cations for narrow S8R sites in distorted Rho and of Cu cations for S6R sites in the centric, open form of Rho. The exsolved Cu,Na-Rho showed improved performance in CO2 /CH4 breakthrough tests, producing pure CH4 with improved uptake and CO2 /CH4 selectivity compared to that of Cu4.9 -Rho.

15.
Phys Chem Chem Phys ; 23(28): 15091-15100, 2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34232235

RESUMO

Li-N-H materials, particularly lithium amide and lithium imide, have been explored for use in a variety of energy storage applications in recent years. Compositional variation within the parent lithium imide, anti-fluorite crystal structure has been related to both its facile storage of hydrogen and impressive catalytic performance for the decomposition of ammonia. Here, we explore the controlled solid-state synthesis of Li-N-H solid-solution anti-fluorite structures ranging from amide-dominated (Li4/3(NH2)2/3(NH)1/3 or Li1.333NH1.667) through lithium imide to majority incorporation of lithium nitride-hydride (Li3.167(NH)0.416N0.584H0.584 or Li3.167NH). Formation of these solid solutions is demonstrated to cause significant changes to the thermal stability and ammonia reactivity of the samples, highlighting the potential use of compositional variation to control the properties of the material in gas storage and catalytic applications.

16.
Angew Chem Int Ed Engl ; 60(30): 16457-16465, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-33951284

RESUMO

We report the aperiodic titanate Ba10 Y6 Ti4 O27 with a room-temperature thermal conductivity that equals the lowest reported for an oxide. The structure is characterised by discontinuous occupancy modulation of each of the sites and can be considered as a quasicrystal. The resulting localisation of lattice vibrations suppresses phonon transport of heat. This new lead material for low-thermal-conductivity oxides is metastable and located within a quaternary phase field that has been previously explored. Its isolation thus requires a precisely defined synthetic protocol. The necessary narrowing of the search space for experimental investigation was achieved by evaluation of titanate crystal chemistry, prediction of unexplored structural motifs that would favour synthetically accessible new compositions, and assessment of their properties with machine-learning models.

17.
Nat Commun ; 11(1): 4280, 2020 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-32855396

RESUMO

The demand for xylenes is projected to increase over the coming decades. The separation of xylene isomers, particularly p- and m-xylenes, is vital for the production of numerous polymers and materials. However, current state-of-the-art separation is based upon fractional crystallisation at 220 K which is highly energy intensive. Here, we report the discrimination of xylene isomers via refinement of the pore size in a series of porous metal-organic frameworks, MFM-300, at sub-angstrom precision leading to the optimal kinetic separation of all three xylene isomers at room temperature. The exceptional performance of MFM-300 for xylene separation is confirmed by dynamic ternary breakthrough experiments. In-depth structural and vibrational investigations using synchrotron X-ray diffraction and terahertz spectroscopy define the underlying host-guest interactions that give rise to the observed selectivity (p-xylene < o-xylene < m-xylene) and separation factors of 4.6-18 for p- and m-xylenes.

18.
Int J Gynaecol Obstet ; 148(1): 127-132, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31677270

RESUMO

This article celebrates the remarkable changes which have occurred in the provision of abortion care in Ireland following the vote to remove the restrictive Eighth Amendment to the Constitution of Ireland in May 2018. However, it also identifies ways in which the emerging legal, ethical and clinical landscape is still impeding the conscientious provision of abortion care. It argues that in order to address these impediments, more attention needs to be paid to the ethical context for conscientious provision. This requires political leadership as well as ongoing leadership by professional bodies to develop both the clinical and the ethical guidance for conscientious provision.


Assuntos
Aborto Legal/ética , Aborto Legal/psicologia , Atitude do Pessoal de Saúde , Feminino , Política de Saúde , Humanos , Irlanda , Masculino , Gravidez , Recusa em Tratar/ética
19.
BJPsych Open ; 5(5): e62, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31530293

RESUMO

BACKGROUND: Only one-third of patients with major depressive disorder achieve remission. One new and promising treatment, ketamine, may prove challenging to implement because of its abuse potential. Although clinicians' views have been sought, we need patients' views before large scale roll-out is considered. AIMS: To explore patients' and carers' views to inform policy and practical decisions about the clinical use of ketamine. METHOD: We carried out a mixed-methods study using data from 44 participants in 21 focus groups in three sessions and an online survey with patients, carers and advocates during a consultation day. Focus groups explored participant's views about ketamine as a form of treatment and the best way for ketamine to be prescribed and monitored. The qualitative data were analysed by two patient-researchers using an exploratory framework analysis and was supplemented by a survey. RESULTS: The ten themes generated were monitoring, information, effect on daily life, side-effects, recreational use, effectiveness, appropriate support, cost, stigma and therapy. Participants wanted better evidence on the safety of ketamine after long-term use and felt that monitoring was required. Collecting this information would provide evidence for ketamine's safe use and administration. There were, however, concerns about the misuse of this information. Practical issues of access were important: repeated travelling to clinics and a lack of sufficiently informed medical staff were key barriers. CONCLUSIONS: Clinicians have some similar and some different views to those of patients, carers and advocates, which need to be considered in any future roll-out of ketamine. DECLARATION OF INTEREST: R.M. has had UK National Institute for Health Research grant funding to study ketamine, is participating in trials of esketamine, runs a clinic that provides ketamine treatment, and has consulted for Johnson & Johnson and Eleusis.

20.
Angew Chem Int Ed Engl ; 58(43): 15401-15406, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31433102

RESUMO

We report the precise postsynthetic control of the composition of ß-Fe1+x Se by electrochemistry with simultaneous tracking of the associated structural changes via in situ synchrotron X-ray diffraction. We access the full phase width of 0.01

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...