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1.
HPB (Oxford) ; 26(6): 764-771, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38480098

RESUMO

BACKGROUND: Optimisation of the future liver remnant (FLR) is crucial to outcomes of extended liver resections. This study aimed to assess the quality of the FLR before and after dual vein embolization (DVE) by quantitative multiparametric MRI. METHODS: Of 100 patients with liver metastases recruited in a clinical trial (Precision1:NCT04597710), ten consecutive patients with insufficient FLR underwent quantitative multiparametric MRI pre- and post-DVE (right portal and hepatic vein). FLR volume, liver fibro-inflammation (corrected T1) scores and fat percentage (proton density fat fraction, PDFF) were determined. Patient metrics were compared by Wilcoxon signed-rank test and statistical analysis done using R software. RESULTS: All patients underwent uncomplicated DVE with improvement in liver remnant health, median 37 days after DVE: cT1 scores reduced from median (interquartile range) 790 ms (753-833 ms) to 741 ms (708-760 ms) p = 0.014 [healthy range <795 ms], as did PDFF from 11% (4-21%), to 3% (2-12%) p = 0.017 [healthy range <5.6%]. There was a significant increase in median (interquartile range) FLR volume from 33% (30-37%)% to 49% (44-52%), p = 0.002. CONCLUSION: This non-invasive and reproducible MRI technique showed improvement in volume and quality of the FLR after DVE. This is a significant advance in our understanding of how to prevent liver failure in patients undergoing major liver surgery.


Assuntos
Embolização Terapêutica , Neoplasias Hepáticas , Imageamento por Ressonância Magnética Multiparamétrica , Valor Preditivo dos Testes , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Hepatectomia , Veias Hepáticas/diagnóstico por imagem , Fígado/diagnóstico por imagem , Fígado/patologia , Neoplasias Hepáticas/terapia , Neoplasias Hepáticas/diagnóstico por imagem , Regeneração Hepática , Veia Porta/diagnóstico por imagem , Fatores de Tempo , Resultado do Tratamento
2.
Acc Chem Res ; 55(20): 3020-3031, 2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-36173244

RESUMO

ConspectusHoley graphene (hG) is a structural derivative of graphene with arrays of through-thickness holes of a few to tens of nanometers in diameter, randomly distributed across the nanosheet surfaces. In most bulk preparation methods, the holes on hG sheets are preferentially generated from the pre-existing defects on graphene. Therefore, contrary to intuitive belief, hG is not necessarily more defective than the intact graphene. Instead, it retains essential parent properties, including high electrical conductivity, high surface area, mechanical robustness, and chemical inertness. Furthermore, the added holey structural motif imparts unique properties that are not present in unmodified graphene, making hG advantageous in numerous applications such as sensing, membranes, reinforcements, and electrochemical energy storage. In particular, the presence of holes enhances the mass transport through the nanosheet plane and thus significantly reduces tortuosity. This difference is a key advantage for using hG in energy storage applications where the transport of ions through the thickness becomes more hindered as the electrode thickness increases to meet practical energy density requirements.An unexpected discovery is that the holes of the hG sheets enable the dry hG powder to be directly compressed into robust monoliths. hG not only can be pressed into monoliths by itself but also can host other electrochemically active materials as a compressible matrix. This important yet unique property, which is not available for other carbon materials including intact graphene, significantly broadens the application horizon in energy storage applications. With the dry compressibility, electrodes with ultrahigh mass loading and thus ultrahigh areal capacity may be conveniently fabricated without toxic solvents or parasitic binders, which are required in conventional slurry-based approaches for electrode fabrication. The dry-press electrode preparation process can be completed within minutes regardless of mass loading. In comparison, high-mass-loading electrodes for advanced battery chemistries using conventional fabrication methods often need stringent and time-consuming process control. hG can also be combined with electrochemically active battery materials while maintaining dry compressibility. This has allowed the unprecedented, convenient manipulation of a wide variety of thick electrode compositions and architectures, which provides not only outstanding performance but also new physical insights for various battery chemistries.In this Account, we first present some basic observations on the dry compressibility of hG as well as the mechanistic investigations from atomistic modeling rationalizing this unique property. We then showcase the applications of neat and composite dry-pressed hG electrodes for various energy storage platforms including supercapacitors, lithium (Li) ion batteries, Li-O2 batteries, and Li-S/Se batteries. The preparation and performance of thick electrodes with practical mass loadings and unique electrode architecture manipulation, both enabled by the dry compressibility of hG, are highlighted and discussed.

3.
Cancer Cell Int ; 23(1): 110, 2023 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-37287008

RESUMO

PURPOSE: Currently, tumor-treating field (TTField) therapy utilizes a single "optimal" frequency of electric fields to achieve maximal cell death in a targeted population of cells. However, because of differences in cell size, shape, and ploidy during mitosis, optimal electric field characteristics for universal maximal cell death may not exist. This study investigated the anti-mitotic effects of modulating electric field frequency as opposed to utilizing uniform electric fields. METHODS: We developed and validated a custom device that delivers a wide variety of electric field and treatment parameters including frequency modulation. We investigated the efficacy of frequency modulating tumor-treating fields on triple-negative breast cancer cells compared to human breast epithelial cells. RESULTS: We show that frequency-modulated (FM) TTFields are as selective at treating triple-negative breast cancer (TNBC) as uniform TTFields while having a greater efficacy for combating TNBC cell growth. TTField treatment at a mean frequency of 150 kHz with a frequency range of ± 10 kHz induced apoptosis in a greater number of TNBC cells after 24 h as compared to unmodulated treatment which led to further decreased cell viability after 48 h. Furthermore, all TNBC cells died after 72 h of FM treatment while cells that received unmodulated treatment were able to recover to cell number equivalent to the control. CONCLUSION: TTFields were highly efficacious against TNBC growth, FM TTFields showed minimal effects on epithelial cells similar to unmodulated treatment.

4.
Malays J Med Sci ; 29(2): 138-156, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35528809

RESUMO

Background: This study aims to explore the Indonesian tourists' demand for medical tourism services in Malaysia. The study also investigates the Indonesian medical tourists' profiles and their preference for Malaysia for medical treatment services. Methods: This study conducted interviews with 49 potential patients from Indonesia who received cardiac treatment at the National Heart Institute (IJN) in Kuala Lumpur, Malaysia. Results: The findings indicate that the key motives of Indonesian tourists travelling to Malaysia for medical treatment are their disappointment with medical practices and inadequate expertise in Indonesia. Besides, they are motivated by peer recommendations, medical expertise, transparency, administration and hospitality in Malaysia. The study findings show that Indonesian medical tourists can be acknowledged as an elite group with stable and above-average income. Conclusion: Results from the study enable medical tourism marketers to better target and segments their potential medical tourists and develop a strategic medical tourism marketing roadmap. This study shows that the high demand for medical tourism is related to Malaysia's availability of niche medical services. Besides, this paper expands the understanding of medical tourists' decision-making and argues its implications for Malaysian health policy and healthcare delivery for the medical tourism industry sustainability.

5.
N Engl J Med ; 378(15): 1386-1395, 2018 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-29526139

RESUMO

BACKGROUND: In an early analysis of this trial, use of a magnetically levitated centrifugal continuous-flow circulatory pump was found to improve clinical outcomes, as compared with a mechanical-bearing axial continuous-flow pump, at 6 months in patients with advanced heart failure. METHODS: In a randomized noninferiority and superiority trial, we compared the centrifugal-flow pump with the axial-flow pump in patients with advanced heart failure, irrespective of the intended goal of support (bridge to transplantation or destination therapy). The composite primary end point was survival at 2 years free of disabling stroke (with disabling stroke indicated by a modified Rankin score of >3; scores range from 0 to 6, with higher scores indicating more severe disability) or survival free of reoperation to replace or remove a malfunctioning device. The noninferiority margin for the risk difference (centrifugal-flow pump group minus axial-flow pump group) was -10 percentage points. RESULTS: Of 366 patients, 190 were assigned to the centrifugal-flow pump group and 176 to the axial-flow pump group. In the intention-to-treat population, the primary end point occurred in 151 patients (79.5%) in the centrifugal-flow pump group, as compared with 106 (60.2%) in the axial-flow pump group (absolute difference, 19.2 percentage points; 95% lower confidence boundary, 9.8 percentage points [P<0.001 for noninferiority]; hazard ratio, 0.46; 95% confidence interval [CI], 0.31 to 0.69 [P<0.001 for superiority]). Reoperation for pump malfunction was less frequent in the centrifugal-flow pump group than in the axial-flow pump group (3 patients [1.6%] vs. 30 patients [17.0%]; hazard ratio, 0.08; 95% CI, 0.03 to 0.27; P<0.001). The rates of death and disabling stroke were similar in the two groups, but the overall rate of stroke was lower in the centrifugal-flow pump group than in the axial-flow pump group (10.1% vs. 19.2%; hazard ratio, 0.47; 95% CI, 0.27 to 0.84, P=0.02). CONCLUSIONS: In patients with advanced heart failure, a fully magnetically levitated centrifugal-flow pump was superior to a mechanical-bearing axial-flow pump with regard to survival free of disabling stroke or reoperation to replace or remove a malfunctioning device. (Funded by Abbott; MOMENTUM 3 ClinicalTrials.gov number, NCT02224755 .).


Assuntos
Insuficiência Cardíaca/terapia , Coração Auxiliar , Desenho de Prótese , Adulto , Idoso , Idoso de 80 Anos ou mais , Pressão Sanguínea , Feminino , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/fisiopatologia , Coração Auxiliar/efeitos adversos , Humanos , Análise de Intenção de Tratamento , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Reoperação/estatística & dados numéricos , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/mortalidade , Trombose/etiologia , Resultado do Tratamento , Teste de Caminhada
6.
Pure Appl Chem ; 93(7)2021.
Artigo em Inglês | MEDLINE | ID: mdl-37965527

RESUMO

This article is the first of three projected IUPAC Technical Reports resulting from IUPAC Project 2011-037-2-100 (Reference Materials for Phase Equilibrium Studies). The goal of that project was to select reference systems with critically evaluated property values for the validation of instruments and techniques used in phase equilibrium studies for mixtures. This Report proposes seven systems for liquid-liquid equilibrium studies, covering the four most common categories of binary mixtures: aqueous systems of moderate solubility, non-aqueous systems, systems with low solubility, and systems with ionic liquids. For each system, the available literature sources, accepted data, smoothing equations, and estimated uncertainties are given.

7.
Pure Appl Chem ; 93(2)2021.
Artigo em Inglês | MEDLINE | ID: mdl-34924633

RESUMO

Scientific projects frequently involve measurements of thermophysical, thermochemical, and other related properties of chemical compounds and materials. These measured property data have significant potential value for the scientific community, but incomplete and inaccurate reporting often hampers their utilization. The present IUPAC Technical Report summarizes the needs of chemical engineers and researchers as consumers of these data and shows how publishing practices can improve information transfer. In the Report, general principles of Good Reporting Practice are developed together with examples illustrating typical cases of reporting issues. Adoption of these principles will improve the quality, reproducibility, and usefulness of experimental data, bring a better level of consistency to results, and increase the efficiency and impact of research. Closely related to Good Reporting Practice, basic elements of Good Research Practice are also introduced with a goal to reduce the number of ambiguities and unresolved problems within the thermophysical property data domain.

8.
Hum Resour Health ; 19(1): 29, 2021 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-33658051

RESUMO

BACKGROUND: Since the 2008 recession, Ireland has experienced large-scale doctor emigration. This paper seeks to ascertain whether (and how) the COVID-19 pandemic might disrupt or reinforce existing patterns of doctor emigration. METHOD: This paper draws on qualitative interviews with 31 hospital doctors in Ireland, undertaken in June-July 2020. As the researchers were subject to a government mandated work-from-home order at that time, they utilised Twitter™ to contact potential respondents (snowball sampling); and conducted interviews via Zoom™ or telephone. FINDINGS: Two cohorts of doctors were identified; COVID Returners (N = 12) and COVID Would-be Emigrants (N = 19). COVID Returners are Irish-trained emigrant doctors who returned to Ireland in March 2020, just as global travel ground to a halt. They returned to be closer to home and in response to a pandemic-related recruitment call issued by the Irish government. COVID Would-be Emigrants are hospital doctors considering emigration. Some had experienced pandemic-related disruptions to their emigration plans as a result of travel restrictions and border closures. However, most of the drivers of emigration mentioned by respondents related to underlying problems in the Irish health system rather than to the pandemic, i.e. a culture of medical emigration, poor working conditions and the limited availability of posts in the Irish health system. DISCUSSION/CONCLUSION: This paper illustrates how the pandemic intensified and reinforced, rather than radically altered, the dynamics of doctor emigration from Ireland. Ireland must begin to prioritise doctor retention and return by developing a coherent policy response to the underlying drivers of doctor emigration.


Assuntos
Atitude do Pessoal de Saúde , COVID-19 , Emigração e Imigração , Satisfação no Emprego , Pandemias , Médicos , Área de Atuação Profissional , Adulto , Recessão Econômica , Emigrantes e Imigrantes , Médicos Graduados Estrangeiros , Humanos , Irlanda , Motivação , Pesquisa Qualitativa , SARS-CoV-2 , Viagem
9.
J Craniofac Surg ; 31(5): 1223-1227, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32282677

RESUMO

BACKGROUND: Isolated sagittal synostosis is the most common form of nonsyndromic craniosynostosis. The surgical management of this condition ranges from strip craniectomy to total cranial vault remodeling. In our unit, passive correction of sagittal synostosis utilizing open extended midline strip craniectomy with bilateral micro-barrel staving is performed before 22 weeks corrected age. The aim of this prospective study is to identify the effectiveness and morbidity associated with this technique. PATIENTS AND METHODS: Nonsyndromic patients who underwent OMEC at a tertiaryreferral-center (Alder Hey Children's Hospital, Liverpool, UK) over a 3-year period (2014-2016) were included. In particular, we looked at pre- and postoperative cranial index (CI), as well as other secondary outcomes such as rates of transfusion and reoperation. RESULTS: A total of 44 patients (12 female, 32 male) met the inclusion criteria. Median age at operation was 132 (range 99-171) days. Median operative time was 117 (range 89-171) minutes. Twenty-four patients underwent a blood transfusion. Median pre-op CI was 66 (range 61-74.7)%. The first post-op CI, taken a median of 56 (range 12-107) days postoperatively, was 78 (range 73-87)%. No patients required reoperation. There were no perioperative deaths. CONCLUSION: Early open extended midline strip craniectomy with bilateral micro-barrel staving for correction of isolated nonsyndromic sagittal synostosis is a safe and effective technique, associated with minimal morbidity, producing sustained satisfactory head shape morphology on short to medium-term follow-up.


Assuntos
Craniossinostoses/cirurgia , Craniotomia , Transfusão de Sangue , Craniotomia/métodos , Feminino , Humanos , Lactente , Masculino , Período Pós-Operatório , Estudos Prospectivos , Procedimentos de Cirurgia Plástica/métodos , Reoperação , Estudos Retrospectivos , Crânio/cirurgia , Resultado do Tratamento
10.
Magn Reson Med ; 81(4): 2666-2675, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30450573

RESUMO

PURPOSE: This preclinical study investigated the use of QSM MRI to noninvasively measure venous oxygen saturation (SvO2) in the hepatic and portal veins. METHODS: QSM data were acquired from a cohort of healthy mice (n = 10) on a 9.4 Tesla MRI scanner under normoxic and hyperoxic conditions. Susceptibility was measured in the portal and hepatic veins and used to calculate SvO2 in each vessel under each condition. Blood was extracted from the inferior vena cava of 3 of the mice under each condition, and SvO2 was measured with a blood gas analyzer for comparison. QSM data were also acquired from a cohort of mice bearing liver tumors under normoxic conditions. Susceptibility was measured, and SvO2 calculated in the portal and hepatic veins and compared to the healthy mice. Statistical significance was assessed using a Wilcoxon matched-pairs signed rank test (normoxic vs. hyperoxic) or a Mann-Whitney test (healthy vs. tumor bearing). RESULTS: SvO2 calculated from QSM measurements in healthy mice under hyperoxia showed significant increases of 15% in the portal vein (P < 0.05) and 21% in the hepatic vein (P < 0.01) versus normoxia. These values agreed with inferior vena cava measurements from the blood gas analyzer (26% increase). SvO2 in the hepatic vein was significantly lower in the colorectal liver metastases cohort (30% ± 11%) than the healthy mice (53% ± 17%) (P < 0.05); differences in the portal vein were not significant. CONCLUSION: QSM is a feasible tool for noninvasively measuring SvO2 in the liver and can detect differences due to increased oxygen consumption in livers bearing colorectal metastases.


Assuntos
Neoplasias Colorretais/diagnóstico por imagem , Veias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/secundário , Imageamento por Ressonância Magnética , Oxigênio/metabolismo , Veia Porta/diagnóstico por imagem , Animais , Gasometria , Calibragem , Veias Cerebrais , Neoplasias Colorretais/patologia , Feminino , Hiperóxia , Camundongos , Metástase Neoplásica , Neoplasias Experimentais , Oximetria , Consumo de Oxigênio , Respiração , Taxa Respiratória , Água
11.
Hum Resour Health ; 17(1): 36, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138211

RESUMO

BACKGROUND: The recession of 2008 triggered large-scale emigration from Ireland. Australia emerged as a popular destination for Irish emigrants and for Irish-trained doctors. This paper illustrates the impact that such an external shock can have on the medical workforce and demonstrates how cross-national data sharing can assist the source country to better understand doctor emigration trends. METHOD: This study draws on Australian immigration, registration and census data to highlight doctor migration flows from Ireland to Australia, 2008-2018. FINDINGS: General population migration from Ireland to Australia increased following the 2008 recession, peaked between 2011 and 2013 before returning to pre-2008 levels by 2014, in line with the general economic recovery in Ireland. Doctor emigration from Ireland to Australia did not follow the same pattern, but rather increased in 2008 and increased year on year since 2014. In 2018, 326 Irish doctors obtained working visas for Australia. That doctor migration is out of sync with general economic conditions in Ireland and with wider migration patterns indicates that it is influenced by factors other than evolving economic conditions in Ireland, perhaps factors relating to the health system. DISCUSSION: Doctor emigration from Ireland to Australia has not decreased in line with improved economic conditions in Ireland, indicating that other factors are driving and sustaining doctor emigration. This paper considers some of these factors. Largescale doctor emigration has significant implications for the Irish health system; representing a brain drain of talent, generating a need for replacement migration and a high dependence on internationally trained doctors. This paper illustrates how source countries, such as Ireland, can use destination country data to inform an evidence-based policy response to doctor emigration.


Assuntos
Médicos Graduados Estrangeiros/estatística & dados numéricos , Austrália/epidemiologia , Recessão Econômica , Emigração e Imigração/estatística & dados numéricos , Política de Saúde , Humanos , Irlanda/etnologia , Área de Atuação Profissional/estatística & dados numéricos
12.
Am J Physiol Renal Physiol ; 314(6): F1145-F1153, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29357432

RESUMO

Noninvasive imaging of the kidney vasculature in preclinical murine models is important for the assessment of renal development, studying diseases and evaluating new therapies but is challenging to achieve using existing imaging modalities. Photoacoustic imaging is a promising new technique that is particularly well suited to visualizing the vasculature and could provide an alternative to existing preclinical imaging methods for studying renal vascular anatomy and function. To investigate this, an all-optical Fabry-Perot-based photoacoustic scanner was used to image the abdominal region of mice. High-resolution three-dimensional, noninvasive, label-free photoacoustic images of the mouse kidney and renal vasculature were acquired in vivo. The scanner was also used to visualize and quantify differences in the vascular architecture of the kidney in vivo due to polycystic kidney disease. This study suggests that photoacoustic imaging could be utilized as a novel preclinical imaging tool for studying the biology of renal disease.


Assuntos
Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Rim/irrigação sanguínea , Técnicas Fotoacústicas , Doenças Renais Policísticas/diagnóstico por imagem , Artéria Renal/diagnóstico por imagem , Veias Renais/diagnóstico por imagem , Animais , Modelos Animais de Doenças , Estudos de Viabilidade , Predisposição Genética para Doença , Imageamento por Ressonância Magnética , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Fenótipo , Doenças Renais Policísticas/genética , Valor Preditivo dos Testes , Canais de Cátion TRPP/genética
13.
Hum Mol Genet ; 25(18): 4094-4106, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27466198

RESUMO

It has been hypothesized that low frequency (1-5% minor allele frequency (MAF)) and rare (<1% MAF) variants with large effect sizes may contribute to the missing heritability in complex traits. Here, we report an association analysis of lipid traits (total cholesterol, LDL-cholesterol, HDL-cholesterol triglycerides) in up to 27 312 individuals with a comprehensive set of low frequency coding variants (ExomeChip), combined with conditional analysis in the known lipid loci. No new locus reached genome-wide significance. However, we found a new lead variant in 26 known lipid association regions of which 16 were >1000-fold more significant than the previous sentinel variant and not in close LD (six had MAF <5%). Furthermore, conditional analysis revealed multiple independent signals (ranging from 1 to 5) in a third of the 98 lipid loci tested, including rare variants. Addition of our novel associations resulted in between 1.5- and 2.5-fold increase in the proportion of heritability explained for the different lipid traits. Our findings suggest that rare coding variants contribute to the genetic architecture of lipid traits.


Assuntos
HDL-Colesterol/genética , LDL-Colesterol/genética , Metabolismo dos Lipídeos/genética , Lipídeos/genética , Adolescente , Adulto , Idoso , Criança , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Exoma/genética , Frequência do Gene , Estudo de Associação Genômica Ampla , Humanos , Lipídeos/sangue , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Triglicerídeos/sangue , Triglicerídeos/genética , População Branca
14.
Artigo em Inglês | MEDLINE | ID: mdl-32514224

RESUMO

Adhesive bonding of composite materials requires reliable monitoring and detection of surface contaminants as part of a vigorous quality control process to assure robust and durable bonded structures. Surface treatment and effective monitoring prior to bonding is essential in order to obtain a surface which is free from contaminants that may lead to inferior bond quality. In this study, the focus is to advance the laser induced breakdown spectroscopy (LIBS) technique by using pulse energies below 100 µJ (µLIBS) for the detection of low levels of silicone contaminants in carbon fiber reinforced polymer (CFRP) composites. Various CFRP surface conditions were investigated by LIBS using ~10 ps, 355 nm laser pulses with pulse energies below 30 µJ. Time-resolved analysis was conducted to optimize the gate delay and gate width for the detection of the C I emission line at 247.9 nm to monitor the epoxy resin matrix of CFRP composites and the Si I emission line at 288.2 nm for detection of silicone contaminants in CFRP. To study the surface sensitivity to silicone contamination, CFRP surfaces were coated with polydimethylsiloxane (PDMS), the active ingredient in many mold release agents. The presence of PDMS was studied by inspecting the Si I emission lines at 251.6 nm and 288.2 nm. The measured PDMS areal densities ranged from 0.15 to 2 µg/cm2. LIBS measurements were performed before and after laser surface ablation. The results demonstrate the successful detection of PDMS thin layers on CFRP using picosecond µLIBS.

15.
Nano Lett ; 17(5): 3252-3260, 2017 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-28362096

RESUMO

Lithium-oxygen (Li-O2) batteries have the highest theoretical energy density of all the Li-based energy storage systems, but many challenges prevent them from practical use. A major obstacle is the sluggish performance of the air cathode, where both oxygen reduction (discharge) and oxygen evolution (charge) reactions occur. Recently, there have been significant advances in the development of graphene-based air cathode materials with a large surface area and catalytically active for both oxygen reduction and evolution reactions, especially with additional catalysts or dopants. However, most studies reported so far have examined air cathodes with a limited areal mass loading rarely exceeding 1 mg/cm2. Despite the high gravimetric capacity values achieved, the actual (areal) capacities of those batteries were far from sufficient for practical applications. Here, we present the fabrication, performance, and mechanistic investigations of high-mass-loading (up to 10 mg/cm2) graphene-based air electrodes for high-performance Li-O2 batteries. Such air electrodes could be easily prepared within minutes under solvent-free and binder-free conditions by compression-molding holey graphene materials because of their unique dry compressibility associated with in-plane holes on the graphene sheet. Li-O2 batteries with high air cathode mass loadings thus prepared exhibited excellent gravimetric capacity as well as ultrahigh areal capacity (as high as ∼40 mAh/cm2). The batteries were also cycled at a high curtailing areal capacity (2 mAh/cm2) and showed a better cycling stability for ultrathick cathodes than their thinner counterparts. Detailed post-mortem analyses of the electrodes clearly revealed the battery failure mechanisms under both primary and secondary modes, arising from the oxygen diffusion blockage and the catalytic site deactivation, respectively. These results strongly suggest that the dry-pressed holey graphene electrodes are a highly viable architectural platform for high-capacity, high-performance air cathodes in Li-O2 batteries of practical significance.

16.
Hum Mol Genet ; 24(18): 5079-92, 2015 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-26082470

RESUMO

The adaptor protein-2 sigma subunit (AP2σ2) is pivotal for clathrin-mediated endocytosis of plasma membrane constituents such as the calcium-sensing receptor (CaSR). Mutations of the AP2σ2 Arg15 residue result in familial hypocalciuric hypercalcaemia type 3 (FHH3), a disorder of extracellular calcium (Ca(2+) o) homeostasis. To elucidate the role of AP2σ2 in Ca(2+) o regulation, we investigated 65 FHH probands, without other FHH-associated mutations, for AP2σ2 mutations, characterized their functional consequences and investigated the genetic mechanisms leading to FHH3. AP2σ2 mutations were identified in 17 probands, comprising 5 Arg15Cys, 4 Arg15His and 8 Arg15Leu mutations. A genotype-phenotype correlation was observed with the Arg15Leu mutation leading to marked hypercalcaemia. FHH3 probands harboured additional phenotypes such as cognitive dysfunction. All three FHH3-causing AP2σ2 mutations impaired CaSR signal transduction in a dominant-negative manner. Mutational bias was observed at the AP2σ2 Arg15 residue as other predicted missense substitutions (Arg15Gly, Arg15Pro and Arg15Ser), which also caused CaSR loss-of-function, were not detected in FHH probands, and these mutations were found to reduce the numbers of CaSR-expressing cells. FHH3 probands had significantly greater serum calcium (sCa) and magnesium (sMg) concentrations with reduced urinary calcium to creatinine clearance ratios (CCCR) in comparison with FHH1 probands with CaSR mutations, and a calculated index of sCa × sMg/100 × CCCR, which was ≥ 5.0, had a diagnostic sensitivity and specificity of 83 and 86%, respectively, for FHH3. Thus, our studies demonstrate AP2σ2 mutations to result in a more severe FHH phenotype with genotype-phenotype correlations, and a dominant-negative mechanism of action with mutational bias at the Arg15 residue.


Assuntos
Complexo 2 de Proteínas Adaptadoras/genética , Subunidades sigma do Complexo de Proteínas Adaptadoras/genética , Códon , Genes Dominantes , Estudos de Associação Genética , Hipercalcemia/congênito , Mutação , Complexo 2 de Proteínas Adaptadoras/química , Subunidades sigma do Complexo de Proteínas Adaptadoras/química , Adolescente , Adulto , Substituição de Aminoácidos , Biomarcadores , Linhagem Celular , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Expressão Gênica , Humanos , Hipercalcemia/diagnóstico , Hipercalcemia/genética , Lactente , Masculino , Pessoa de Meia-Idade , Modelos Moleculares , Linhagem , Fenótipo , Conformação Proteica , Relação Estrutura-Atividade , Adulto Jovem
17.
Am J Hum Genet ; 94(3): 349-60, 2014 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-24560520

RESUMO

Blood pressure (BP) is a heritable risk factor for cardiovascular disease. To investigate genetic associations with systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP), we genotyped ~50,000 SNPs in up to 87,736 individuals of European ancestry and combined these in a meta-analysis. We replicated findings in an independent set of 68,368 individuals of European ancestry. Our analyses identified 11 previously undescribed associations in independent loci containing 31 genes including PDE1A, HLA-DQB1, CDK6, PRKAG2, VCL, H19, NUCB2, RELA, HOXC@ complex, FBN1, and NFAT5 at the Bonferroni-corrected array-wide significance threshold (p < 6 × 10(-7)) and confirmed 27 previously reported associations. Bioinformatic analysis of the 11 loci provided support for a putative role in hypertension of several genes, such as CDK6 and NUCB2. Analysis of potential pharmacological targets in databases of small molecules showed that ten of the genes are predicted to be a target for small molecules. In summary, we identified previously unknown loci associated with BP. Our findings extend our understanding of genes involved in BP regulation, which may provide new targets for therapeutic intervention or drug response stratification.


Assuntos
Pressão Sanguínea , Diástole , Genética Populacional , Sístole , População Branca/genética , Pressão Arterial , Biologia Computacional/métodos , Europa (Continente) , Loci Gênicos , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Fenótipo , Polimorfismo de Nucleotídeo Único , Controle de Qualidade , Locos de Características Quantitativas , Fatores de Risco
18.
Int J Mol Sci ; 18(3)2017 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-28272372

RESUMO

The majority of genes contributing to the heritable component of blood pressure remain unidentified, but there is substantial evidence to suggest that common polymorphisms at loci involved in the biosynthesis of the corticosteroids aldosterone and cortisol are important. This view is supported by data from genome-wide association studies that consistently link the CYP17A1 locus to blood pressure. In this review article, we describe common polymorphisms at three steroidogenic loci (CYP11B2, CYP11B1 and CYP17A1) that alter gene transcription efficiency and levels of key steroids, including aldosterone. However, the mechanism by which this occurs remains unclear. While the renin angiotensin system is rightly regarded as the major driver of aldosterone secretion, there is increasing evidence that the contribution of corticotropin (ACTH) is also significant. In light of this, we propose that the differential response of variant CYP11B2, CYP11B1 and CYP17A1 genes to ACTH is an important determinant of blood pressure, tending to predispose individuals with an unfavourable genotype to hypertension.


Assuntos
Hormônio Adrenocorticotrópico/genética , Aldosterona/metabolismo , Pressão Sanguínea/fisiologia , Polimorfismo Genético , Locos de Características Quantitativas , Hormônio Adrenocorticotrópico/sangue , Animais , Citocromo P-450 CYP11B2/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Genótipo , Humanos , Hipertensão/genética , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Esteroide 11-beta-Hidroxilase/genética , Esteroide 17-alfa-Hidroxilase/genética
19.
Angew Chem Int Ed Engl ; 56(24): 6970-6974, 2017 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-28510337

RESUMO

Metal-air batteries, especially Li-air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO2 (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li2 CO3 , making the battery less rechargeable. To make the Li-CO2 batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO2 reduction and evolution reactions and investigate the electrochemical behavior of Li-CO2 batteries. Here, we demonstrate a rechargeable Li-CO2 battery with a high reversibility by using B,N-codoped holey graphene as a highly efficient catalyst for CO2 reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as-prepared Li-CO2 batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long-term cycling stability over 200 cycles at a high current density of 1.0 A g-1 . Our results open up new possibilities for the development of long-term Li-air batteries reusable under ambient conditions, and the utilization and storage of CO2 .

20.
Nanotechnology ; 27(34): 342002, 2016 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-27418239

RESUMO

Advanced doping technologies are key for the continued scaling of semiconductor devices and the maintenance of device performance beyond the 14 nm technology node. Due to limitations of conventional ion-beam implantation with thin body and 3D device geometries, techniques which allow precise control over dopant diffusion and concentration, in addition to excellent conformality on 3D device surfaces, are required. Spin-on doping has shown promise as a conventional technique for doping new materials, particularly through application with other dopant methods, but may not be suitable for conformal doping of nanostructures. Additionally, residues remain after most spin-on-doping processes which are often difficult to remove. In situ doping of nanostructures is especially common for bottom-up grown nanostructures but problems associated with concentration gradients and morphology changes are commonly experienced. Monolayer doping has been shown to satisfy the requirements for extended defect-free, conformal and controllable doping on many materials ranging from traditional silicon and germanium devices to emerging replacement materials such as III-V compounds but challenges still remain, especially with regard to metrology and surface chemistry at such small feature sizes. This article summarises and critically assesses developments over the last number of years regarding the application of gas and solution phase techniques to dope silicon-, germanium- and III-V-based materials and nanostructures to obtain shallow diffusion depths coupled with high carrier concentrations and abrupt junctions.

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