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1.
Inorg Chem ; 62(8): 3629-3636, 2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36780272

RESUMO

Vacancy-ordered halide perovskites have received great interest in optoelectronic applications. In this work, we report the novel inorganic halide Cs10MnSb6Cl30 with a distinctive 10H (10-layer hexagonal) perovskite polytype structure with (hcccc)2 stacking. Cs10MnSb6Cl30 has 30% B-site vacancies ordered at both corner- and face-sharing sites, resulting in [MnSb6Cl30]10-n columns, i.e., a reduction of octahedral connectivity to 1D. This results in enhanced photoluminescence in comparison to the previously reported 25% vacancy-ordered 3C polytype Cs4MnSb2Cl12 with 2D connectivity. This demonstrates not only the existence of the 10H perovskite structure in halides but also demonstrates the degree of B-site deficiency and stacking sequence variation as a direction to tune the optical properties of perovskite polytypes via vacancy rearrangements.

2.
Chem Mater ; 34(5): 2458-2467, 2022 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-35431437

RESUMO

Two-dimensional (2D) organic-inorganic hybrid copper halide perovskites have drawn tremendous attention as promising multifunctional materials. Herein, by incorporating ortho-, meta-, and para-chlorine substitutions in the benzylamine structure, we first report the influence of positional isomerism on the crystal structures of chlorobenzylammonium copper(II) chloride perovskites A2CuCl4. 2D polar ferromagnets (3-ClbaH)2CuCl4 and (4-ClbaH)2CuCl4 (ClbaH+ = chlorobenzylammonium) are successfully obtained. They both adopt a polar monoclinic space group Cc at room temperature, displaying significant differences in crystal structures. In contrast, (2-ClbaH)2CuCl4 adopts a centrosymmetric space group P 21/ c at room temperature. This associated structural evolution successfully enhances the physical properties of the two polar compounds with high thermal stability, discernible second harmonic generation (SHG) signals, ferromagnetism, and narrow optical band gaps. These findings demonstrate that the introduction of chlorine atoms into the interlayer organic species is a powerful tool to tune crystal symmetries and physical properties, and this inspires further exploration of designing high-performance multifunctional copper-based materials.

3.
Inorg Chem ; 61(7): 3230-3239, 2022 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-35138839

RESUMO

We present the influence of positional isomerism on the crystal structure of fluorobenzylammonium copper(II) chloride perovskites A2CuCl4 by incorporating ortho-, meta-, and para-fluorine substitution in the benzylamine structure. Two-dimensional (2D) polar ferromagnet (3-FbaH)2CuCl4 (3-FbaH+ = 3-fluorobenzylammonium) is successfully obtained, which crystallizes in a polar orthorhombic space group Pca21 at room temperature. In contrast, both (2-FbaH)2CuCl4 (2-FbaH+ = 2-fluorobenzylammonium) and (4-FbaH)2CuCl4 (4-FbaH+ = 4-fluorobenzylammonium) crystallize in centrosymmetric space groups P21/c and Pnma at room temperature, respectively, displaying significant differences in crystal structures. These differences indicate that the position of the fluorine atom is a driver for the polar behavior in (3-FbaH)2CuCl4. Preliminary magnetic measurements confirm that these three perovskites possess dominant ferromagnetic interactions within the inorganic [CuCl4]∞ layers. Therefore, (3-FbaH)2CuCl4 is a polar ferromagnet, with potential as a type I multiferroic. This work is expected to promote further development of high-performance 2D copper(II) halide perovskite multiferroic materials.

4.
Molecules ; 26(21)2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34770883

RESUMO

A family of Ruddlesden-Popper (n = 1) layered perovskite-related phases, Az2PbClxBr4-x with composition 0 ≤ x ≤ 4 were obtained using mechanosynthesis. These compounds are isostructural with K2NiF4 and therefore adopt the idealised n = 1 Ruddlesden-Popper structure. A linear variation in unit cell volume as a function of anion average radius is observed. A tunable bandgap is achieved, ranging from 2.81 to 3.43 eV, and the bandgap varies in a second-order polynomial relationship with the halide composition.

5.
Inorg Chem ; 60(16): 12247-12254, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34319709

RESUMO

Mixed halide azetidinium lead perovskites AzPbBr3-xXx (X = Cl or I) were obtained by mechanosynthesis. With varying halide composition from Cl- to Br- to I-, the chloride and bromide analogues both form in the hexagonal 6H polytype while the iodide adopts the 9R polytype. An intermediate 4H polytype is observed for mixed Br/I compositions. Overall, the structure progresses from 6H to 4H to 9R perovskite polytype with varying halide composition. Rietveld refinement of the powder X-ray diffraction patterns revealed a linear variation in unit cell volume as a function of the average radius of the anion, which not only is observed within the solid solution of each polytype (according to Vegard's law) but also extends uniformly across all three polytypes. This is correlated to a progressive (linear) tuning of the bandgap from 3.43 to 2.00 eV. Regardless of halide, the family of azetidinium halide perovskite polytypes are highly stable, with no discernible change in properties over more than 6 months under ambient conditions.

6.
PLoS One ; 16(4): e0249297, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33909630

RESUMO

BACKGROUND: Prognosis in Palliative care Study (PiPS) models predict survival probabilities in advanced cancer. PiPS-A (clinical observations only) and PiPS-B (additionally requiring blood results) consist of 14- and 56-day models (PiPS-A14; PiPS-A56; PiPS-B14; PiPS-B56) to create survival risk categories: days, weeks, months. The primary aim was to compare PIPS-B risk categories against agreed multi-professional estimates of survival (AMPES) and to validate PiPS-A and PiPS-B. Secondary aims were to assess acceptability of PiPS to patients, caregivers and health professionals (HPs). METHODS AND FINDINGS: A national, multi-centre, prospective, observational, cohort study with nested qualitative sub-study using interviews with patients, caregivers and HPs. Validation study participants were adults with incurable cancer; with or without capacity; recently referred to community, hospital and hospice palliative care services across England and Wales. Sub-study participants were patients, caregivers and HPs. 1833 participants were recruited. PiPS-B risk categories were as accurate as AMPES [PiPS-B accuracy (910/1484; 61%); AMPES (914/1484; 61%); p = 0.851]. PiPS-B14 discrimination (C-statistic 0.837) and PiPS-B56 (0.810) were excellent. PiPS-B14 predictions were too high in the 57-74% risk group (Calibration-in-the-large [CiL] -0.202; Calibration slope [CS] 0.840). PiPS-B56 was well-calibrated (CiL 0.152; CS 0.914). PiPS-A risk categories were less accurate than AMPES (p<0.001). PiPS-A14 (C-statistic 0.825; CiL -0.037; CS 0.981) and PiPS-A56 (C-statistic 0.776; CiL 0.109; CS 0.946) had excellent or reasonably good discrimination and calibration. Interviewed patients (n = 29) and caregivers (n = 20) wanted prognostic information and considered that PiPS may aid communication. HPs (n = 32) found PiPS user-friendly and considered risk categories potentially helpful for decision-making. The need for a blood test for PiPS-B was considered a limitation. CONCLUSIONS: PiPS-B risk categories are as accurate as AMPES made by experienced doctors and nurses. PiPS-A categories are less accurate. Patients, carers and HPs regard PiPS as potentially helpful in clinical practice. STUDY REGISTRATION: ISRCTN13688211.


Assuntos
Cuidadores/psicologia , Pessoal de Saúde/psicologia , Neoplasias/patologia , Cuidados Paliativos , Pacientes/psicologia , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Humanos , Entrevistas como Assunto , Masculino , Pessoa de Meia-Idade , Neoplasias/terapia , Prognóstico , Estudos Prospectivos , Fatores de Risco
7.
PLoS One ; 16(4): e0249763, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33909658

RESUMO

PURPOSE: The Palliative Prognostic (PaP) score; Palliative Prognostic Index (PPI); Feliu Prognostic Nomogram (FPN) and Palliative Performance Scale (PPS) have all been proposed as prognostic tools for palliative cancer care. However, clinical judgement remains the principal way by which palliative care professionals determine prognoses and it is important that the performance of prognostic tools is compared against clinical predictions of survival (CPS). METHODS: This was a multi-centre, cohort validation study of prognostic tools. Study participants were adults with advanced cancer receiving palliative care, with or without capacity to consent. Key prognostic data were collected at baseline, shortly after referral to palliative care services. CPS were obtained independently from a doctor and a nurse. RESULTS: Prognostic data were collected on 1833 participants. All prognostic tools showed acceptable discrimination and calibration, but none showed superiority to CPS. Both PaP and CPS were equally able to accurately categorise patients according to their risk of dying within 30 days. There was no difference in performance between CPS and FPN at stratifying patients according to their risk of dying at 15, 30 or 60 days. PPI was significantly (p<0.001) worse than CPS at predicting which patients would survive for 3 or 6 weeks. PPS and CPS were both able to discriminate palliative care patients into multiple iso-prognostic groups. CONCLUSIONS: Although four commonly used prognostic algorithms for palliative care generally showed good discrimination and calibration, none of them demonstrated superiority to CPS. Prognostic tools which are less accurate than CPS are of no clinical use. However, prognostic tools which perform similarly to CPS may have other advantages to recommend them for use in clinical practice (e.g. being more objective, more reproducible, acting as a second opinion or as an educational tool). Future studies should therefore assess the impact of prognostic tools on clinical practice and decision-making.


Assuntos
Neoplasias/terapia , Cuidados Paliativos/métodos , Médicos/normas , Idoso , Técnicas de Apoio para a Decisão , Feminino , Humanos , Masculino , Neoplasias/diagnóstico , Neoplasias/mortalidade , Relações Médico-Paciente , Valor Preditivo dos Testes , Estudos Prospectivos , Taxa de Sobrevida
8.
Adv Mater ; 31(40): e1903620, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31389099

RESUMO

Since the observation that the properties of ferroic domain walls (DWs) can differ significantly from the bulk materials in which they are formed, it has been realized that domain wall engineering offers exciting new opportunities for nanoelectronics and nanodevice architectures. Here, a novel improper ferroelectric, CsNbW2 O9 , with the hexagonal tungsten bronze structure, is reported. Powder neutron diffraction and symmetry mode analysis indicate that the improper transition (TC = 1100 K) involves unit cell tripling, reminiscent of the hexagonal rare earth manganites. However, in contrast to the manganites, the symmetry breaking in CsNbW2 O9 is electronically driven (i.e., purely displacive) via the second-order Jahn-Teller effect in contrast to the geometrically driven tilt mechanism of the manganites. Nevertheless CsNbW2 O9 displays the same kinds of domain microstructure as those found in the manganites, such as the characteristic six-domain "cloverleaf" vertices and DW sections with polar discontinuities. The discovery of a completely new material system, with domain patterns already known to generate interesting functionality in the manganites, is important for the emerging field of DW nanoelectronics.

9.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 75(Pt 5): 815-821, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32830760

RESUMO

The ambient-temperature structures (orthorhombic, space group Cmc21) of the polar hexagonal tungsten bronzes RbNbW2O9 and KNbW2O9 have been determined by high-resolution powder neutron diffraction. Displacement of the A-site cation along the polar c axis with concomitant octahedral tilting occurs to optimize the A cation bonding environment, hence reducing the coordination from 18 to 16. This effect is more evident in KNbW2O9 due to decreased A cation size. The octahedral tilting in both compositions results in a doubling of the c axis that has not previously been reported, highlighting the importance of neutron diffraction as a complementary technique for structural determination of such systems.

10.
Neuroscience ; 392: 38-56, 2018 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-30267830

RESUMO

The impact of treating astrocytes with the astrocytic toxin l-alpha amino adipic acid (L-AAA) on neuronal outgrowth, complexity and synapse formation was assessed, using a model of astrocyte-neuronal interaction. Treatment of rat primary cortical neurons with conditioned media (CM) derived from astrocytes treated with L-AAA reduced neuronal complexity and synapse formation. L-AAA provoked a reduction in the expression of glial fibrillary acid protein (GFAP) and a reduction in ATP-linked mitochondrial respiration in astrocytic cells. As the NMDA-R/PSD-95/NOS signaling pathway is implicated in regulating the structural plasticity of neurons, treatment of neuronal cultures with the neuronal nitric oxide synthase (nNOS) inhibitor 1-[2-(trifluoromethyl)phenyl] imidazole (TRIM) [100 nM] was assessed and observed to protect against L-AAA-treated astrocytic CM-induced reduction in neuronal complexity and synapse loss. Treatment with the NMDA-R antagonist ketamine protected against the CM-induced loss of synapse formation whereas the novel PSD-95/nNOS inhibitors 2-((1H-benzo[d] [1,2,3]triazol-5-ylamino) methyl)-4,6-dichlorophenol (IC87201) and 4-(3,5-dichloro-2-hydroxy-benzylamino)-2-hydroxybenzoic acid (ZL006) protected against synapse loss with partial protection against reduced neurite outgrowth. Furthermore, L-AAA delivery to the pre-limbic cortex (PLC) of mice was found to increase dendritic spine density and treatment with ZL006 reduced this effect. In summary, L-AAA-induced astrocyte impairment leads to a loss of neuronal complexity and synapse loss in vitro and increased dendritic spine density in vivo that may be reversed by inhibitors of the NMDA-R/PSD-95/NOS pathway. The results have implications for understanding astrocytic-neuronal interaction and the search for drug candidates that may provide therapeutic approaches for brain disorders associated with astrocytic histopathology.


Assuntos
Ácido 2-Aminoadípico/toxicidade , Astrócitos/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Óxido Nítrico/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/metabolismo , Animais , Astrócitos/metabolismo , Atrofia , Meios de Cultivo Condicionados , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/patologia , Feminino , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neurônios/efeitos dos fármacos , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico Sintase Tipo I/metabolismo , Cultura Primária de Células , Ratos Wistar , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Sinapses/efeitos dos fármacos , Sinapses/patologia
11.
Radiography (Lond) ; 24(2): 159-164, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29605114

RESUMO

INTRODUCTION: Time delays and errors exist which lead to delays in patient care and misdiagnosis. Reporting clinicians follow guidance to form their own search strategy. However, little research has tested these training guides. With the use of eye tracking technology and expert input we developed a digital training platform to be used in chest image interpretation learning. METHODS: Two sections of a digital training platform were planned and developed; A) a search strategy training tool to assist reporters during their interpretation of images, and B) an educational tool to communicate the search strategies of expert viewers to trainees by using eye tracking technology. RESULTS: A digital training platform for use in chest image interpretation was created based on evidence within the literature, expert input and two search strategies previously used in clinical practice. Images and diagrams, aiding translation of the platform content, were incorporated where possible. The platform is structured to allow the chest image interpretation process to be clear, concise and methodical. CONCLUSION: A search strategy was incorporated within the tool to investigate its use, with the possibility that it could be recommended as an evidence based approach for use by reporting clinicians. Eye tracking, a checklist and voice recordings have been combined to form a multi-dimensional learning tool, which has never been used in chest image interpretation learning before. The training platform for use in chest image interpretation learning has been designed, created and digitised. Future work will establish the efficacy of the developed approaches.


Assuntos
Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Radiografia Torácica , Radiologia/educação , Lista de Checagem , Erros de Diagnóstico/prevenção & controle , Movimentos Oculares , Humanos , Capacitação em Serviço , Interface Usuário-Computador , Gravação em Vídeo
12.
Annu Int Conf IEEE Eng Med Biol Soc ; 2017: 821-824, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29059998

RESUMO

Hypertension, a silent killer, is the biggest challenge of the 21st century in public health agencies worldwide [1]. World Health Organization (WHO) statistic shows that the mortality rate of hypertension is 9.4 million per year and causes 55.3% of total deaths in cardiovascular (CV) patients [2]. Early detection and prevention of hypertension can significantly reduce the CV mortality. We are presenting a wireless chest wearable vital sign monitoring platform. It measures Electrocardiogram (ECG), Photoplethsmogram (PPG) and Ballistocardiogram (BCG) signals and sends data over Bluetooth low energy (BLE) to mobile phone-acts as a gateway. A custom android application relays the data to thingspeak server where MATLAB based offline analysis estimates the blood pressure. A server reacts on the health of subject to friends & family on the social media - twitter. The chest provides a natural position for the sensor to capture legitimate signals for hypertension condition. We have done a clinical technical evaluation of prototypes on 11 normotensive subjects, 9 males 2 females.


Assuntos
Dispositivos Eletrônicos Vestíveis , Balistocardiografia , Determinação da Pressão Arterial , Eletrocardiografia , Feminino , Humanos , Hipertensão , Masculino , Tecnologia sem Fio
13.
Lab Chip ; 15(11): 2412-8, 2015 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-25900329

RESUMO

Long-term culture and monitoring of individual multicellular spheroids and embryoid bodies (EBs) remains a challenge for in vitro cell propagation. Here, we used a continuous 3D projection printing approach - with an important modification of nonlinear exposure - to generate concave hydrogel microstructures that permit spheroid growth and long-term maintenance, without the need for spheroid transfer. Breast cancer spheroids grown to 10 d in the concave structures showed hypoxic cores and signs of necrosis using immunofluorescent and histochemical staining, key features of the tumor microenvironment in vivo. EBs consisting of induced pluripotent stem cells (iPSCs) grown on the hydrogels demonstrated narrow size distribution and undifferentiated markers at 3 d, followed by signs of differentiation by the presence of cavities and staining of the three germ layers at 10 d. These findings demonstrate a new method for long-term (e.g. beyond spheroid formation at day 2, and with media exchange) 3D cell culture that should be able to assist in cancer spheroid studies as well as embryogenesis and patient-derived disease modeling with iPSC EBs.


Assuntos
Técnicas de Cultura de Células/instrumentação , Corpos Embrioides/citologia , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Impressão Tridimensional , Esferoides Celulares/citologia , Bioengenharia , Linhagem Celular Tumoral , Humanos
14.
Dalton Trans ; 44(23): 10738-45, 2015 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-25687218

RESUMO

A series of isovalently A-site substituted relaxor dielectric tetragonal tungsten bronzes of general formula Ba(6-x-y)Sr(x)Ca(y)GaNb(9)O(30) were investigated. The long-range (average) crystal structure as determined by conventional diffraction techniques varies monotonically according to Vegard's law. The dielectric properties, however, do not display a similar, simple "average size" dependence and instead show a dependence on the statistical size variance, i.e. size mismatch, of the A-cation. The difficulties in Vogel-Fulcher analysis of relative permittivity and the complementary approach of using dielectric loss data fitted to Jonscher's empirical universal dielectric relaxation model is discussed.

15.
Dalton Trans ; 44(23): 10673-80, 2015 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-25629659

RESUMO

The layered perovskite LaTaO(4) has been prepared in its polar orthorhombic polymorphic form at ambient temperature. Although no structural phase transition is observed in the temperature interval 25° C < T < 500 °C, a very large axial thermal contraction effect is seen, which can be ascribed to an anomalous buckling of the perovskite octahedral layer. The non-polar monoclinic polymorph can be stabilised at ambient temperature by Nd-doping. A composition La(0.90)Nd(0.10)TaO(4) shows a first-order monoclinic-orthorhombic (non-polar to polar) transition in the region 250° C < T < 350 °C. Dielectric responses are observed at both the above structural events but, despite the 'topological ferroelectric' nature of orthorhombic LaTaO(4), we have not succeeded in obtaining ferroelectric P-E hysteresis behaviour. Structural relationships in the wider family of A(n)B(n)X(3n+2) layered perovskites are discussed.

16.
J Electrocardiol ; 48(1): 43-4, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25465863

RESUMO

The 12-lead electrocardiogram (ECG) is a complex set of cardiac signals that require a high degree of skill and clinical knowledge to interpret. Therefore, it is imperative to record and understand how expert readers interpret the 12-lead ECG. This short paper showcases how eye tracking technology and audio data can be fused together and visualised to gain insight into the interpretation techniques employed by an eminent ECG champion, namely Dr Rory Childers.


Assuntos
Cardiologia/história , Competência Clínica , Documentação/história , Eletrocardiografia/história , Movimentos Oculares , História do Século XXI , Estados Unidos
17.
J Electrocardiol ; 47(6): 895-906, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25110276

RESUMO

INTRODUCTION: It is well known that accurate interpretation of the 12-lead electrocardiogram (ECG) requires a high degree of skill. There is also a moderate degree of variability among those who interpret the ECG. While this is the case, there are no best practice guidelines for the actual ECG interpretation process. Hence, this study adopts computerized eye tracking technology to investigate whether eye-gaze can be used to gain a deeper insight into how expert annotators interpret the ECG. Annotators were recruited in San Jose, California at the 2013 International Society of Computerised Electrocardiology (ISCE). METHODS: Each annotator was recruited to interpret a number of 12-lead ECGs (N=12) while their eye gaze was recorded using a Tobii X60 eye tracker. The device is based on corneal reflection and is non-intrusive. With a sampling rate of 60Hz, eye gaze coordinates were acquired every 16.7ms. Fixations were determined using a predefined computerized classification algorithm, which was then used to generate heat maps of where the annotators looked. The ECGs used in this study form four groups (3=ST elevation myocardial infarction [STEMI], 3=hypertrophy, 3=arrhythmias and 3=exhibiting unique artefacts). There was also an equal distribution of difficulty levels (3=easy to interpret, 3=average and 3=difficult). ECGs were displayed using the 4x3+1 display format and computerized annotations were concealed. RESULTS: Precisely 252 expert ECG interpretations (21 annotators×12 ECGs) were recorded. Average duration for ECG interpretation was 58s (SD=23). Fleiss' generalized kappa coefficient (Pa=0.56) indicated a moderate inter-rater reliability among the annotators. There was a 79% inter-rater agreement for STEMI cases, 71% agreement for arrhythmia cases, 65% for the lead misplacement and dextrocardia cases and only 37% agreement for the hypertrophy cases. In analyzing the total fixation duration, it was found that on average annotators study lead V1 the most (4.29s), followed by leads V2 (3.83s), the rhythm strip (3.47s), II (2.74s), V3 (2.63s), I (2.53s), aVL (2.45s), V5 (2.27s), aVF (1.74s), aVR (1.63s), V6 (1.39s), III (1.32s) and V4 (1.19s). It was also found that on average the annotator spends an equal amount of time studying leads in the frontal plane (15.89s) when compared to leads in the transverse plane (15.70s). It was found that on average the annotators fixated on lead I first followed by leads V2, aVL, V1, II, aVR, V3, rhythm strip, III, aVF, V5, V4 and V6. We found a strong correlation (r=0.67) between time to first fixation on a lead and the total fixation duration on each lead. This indicates that leads studied first are studied the longest. There was a weak negative correlation between duration and accuracy (r=-0.2) and a strong correlation between age and accuracy (r=0.67). CONCLUSIONS: Eye tracking facilitated a deeper insight into how expert annotators interpret the 12-lead ECG. As a result, the authors recommend ECG annotators to adopt an initial first impression/pattern recognition approach followed by a conventional systematic protocol to ECG interpretation. This recommendation is based on observing misdiagnoses given due to first impression only. In summary, this research presents eye gaze results from expert ECG annotators and provides scope for future work that involves exploiting computerized eye tracking technology to further the science of ECG interpretation.


Assuntos
Arritmias Cardíacas/diagnóstico , Inteligência Artificial , Eletrocardiografia/métodos , Movimentos Oculares/fisiologia , Fixação Ocular/fisiologia , Percepção Visual/fisiologia , Adulto , Competência Clínica , Feminino , Humanos , Masculino , Leitura
18.
Dalton Trans ; 43(30): 11687-95, 2014 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-24950736

RESUMO

The effect of A-cation size on the structural and electrical properties in a family of ferroelectric tetragonal tungsten bronzes (TTBs) Ba4R(0.67)□(1.33)Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y; □ = vacancy) was investigated. In each case, the crystal structure, as determined from lab-based ambient powder X-ray diffraction (PXRD), is metrically tetragonal and can be refined in the P4bm space group. XRD data show an increased splitting of hk0 00l reflections with decreasing R cation size indicating an increasing tetragonal distortion (measured by tetragonality c/a). Dielectric data and ferroelectric measurements indicate that the ferroelectric Curie temperature, T(C), increases with decreasing R size and so a direct correlation between T(C) and tetragonality/ionic radius of R is demonstrated. Rietveld refinements show that the large A2-site is fully occupied by Ba(2+) and, in addition to the R cation size, the presence of vacancies at the A1-site (perovskite-like site) is also shown to strongly affect the stability of ferroelectricity in this structure type.

19.
Philos Trans A Math Phys Eng Sci ; 372(2009): 20120451, 2014 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-24421377

RESUMO

We discuss the strategy for development of novel functional materials with the tetragonal tungsten bronze structure. From the starting composition Ba6GaNb9O30, the effect of A- and B-site substitutions on the dielectric properties is used to develop an understanding of the origin and stability of the dipolar response in these compounds. Both tetragonal strain induced by large B-site cations and local strain variations created by isovalent A-site substitutions enhance dipole stability but result in a dilute, weakly correlated dipolar response and canonical relaxor behaviour. Decreasing cation size at the perovskite A2-site increases the dipolar displacements in the surrounding octahedra, but insufficiently to result in dipole ordering. Mechanisms introducing small A-site lanthanide cations and incorporation of A-site vacancies to induce ferroelectricity and magnetism are presented.

20.
Br J Dermatol ; 169 Suppl 2: 32-8, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23786618

RESUMO

In human skin fibroblasts in vitro, procollagen-1 and NAD(+)/NADH were reduced in three strains of adult fibroblasts compared with neonatal fibroblasts. The levels of both procollagen-1 and NAD(+)/NADH were increased in the adult fibroblasts by treatment for 24 (NAD energy) or 48 h (procollagen-1) with a complex containing niacinamide, Pal-KTTKS peptide and an olive oil fatty acid derivative (Olivem(®)), especially in combination with a natural extract from dill (Lys'lastine V(®)). In one of the adult fibroblast strains evaluated, these changes in procollagen-1 and NAD(+)/NADH in response to the complex of bioactives were in parallel with increased expression of mRNA biomarkers related primarily to dermal matrix and basement membrane structure, including COL1A1, COL3A1, COL5A1, COL14A1, ELN and LOXL2, in addition to SOD2, NAMPT and TGFBR3; MMP1 was decreased in expression. In general, these mRNA biomarker effects were maintained or boosted by the addition of Lys'lastine V, particularly at 1%, and were similar to the fold changes in mRNA expression in neonatal compared with adult fibroblasts. These results indicate that the complex of niacinamide, Pal-KTTKS and Olivem, especially with addition of Lys'lastine V, increases the NAD(+)/NADH bioenergy level of adult skin fibroblasts in parallel with increased expression of skin structure biomarkers in vitro to levels similar to those in younger fibroblasts. Thus, niacinamide, Pal-KTTKS, Olivem and Lys'lastine V are promising bioactive candidates for inclusion in cosmetic formulations.


Assuntos
Metabolismo Energético/fisiologia , Niacinamida/farmacologia , Oligopeptídeos/farmacologia , Óleos de Plantas/farmacologia , Envelhecimento da Pele/fisiologia , Pele/efeitos dos fármacos , Adulto , Células Cultivadas , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Feminino , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Recém-Nascido , Masculino , Pessoa de Meia-Idade , NAD/genética , NAD/metabolismo , Azeite de Oliva , Extratos Vegetais/farmacologia , RNA Mensageiro/metabolismo , Pele/citologia , Pele/metabolismo
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