Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Stroke Cerebrovasc Dis ; 33(8): 107818, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38871260

RESUMO

BACKGROUND: Since the efficacy and safety of endovascular thrombectomy (EVT) in patients with acute ischemic stroke with a large infarct area is still inconclusive, we sought to compare functional and neurological outcomes with the use of endovascular thrombectomy versus medical care alone. METHODS: We searched MEDLINE (via PubMed), Embase, Cochrane Library, ClinicalTrials.gov, and the International Clinical Trials Registry Platform (ICTRP) to retrieve all the relevant randomized controlled trials (RCTs) on this topic. Review manager (RevMan) was used to perform meta-analyses using a random-effect model. Dichotomous outcomes were pooled using risk ratios (RR) with 95% confidence intervals (CIs). RESULTS: Our meta-analysis included 6 RCTs with a total of 1665 patients. Most studies included patients with an ASPECTS score of 3-5. Our results demonstrate that endovascular thrombectomy significantly increased the rates of functional independence (mRS ≤ 2) (RR, 2.49; 95% CI, 1.89-3.29) and moderate neurological outcome (mRS ≤ 3) (RR, 1.90; 95% CI, 1.50-2.40) at 90 days. The benefit of EVT for these outcomes remained the same at 1-year follow-up. Endovascular thrombectomy was associated with increased rates of early neurological improvement (RR, 2.22; 95% CI, 1.53-3.22), excellent neurological recovery (mRS ≤ 1) (RR, 1.75; 95% CI, 1.02-3.03), and decreased rate of poor neurological recovery (mRS 4-6) (RR, 0.81; 95% CI, 0.76-0.86). No significant difference was found between the two groups regarding all-cause mortality (RR, 0.86; 95% CI, 0.72-1.02), decompressive craniectomy (RR, 1.32; 95% CI, 0.89-1.94), and the incidence of serious adverse effects (RR, 1.39; 95% CI, 0.83-2.32) between the two groups. Endovascular thrombectomy significantly increased the rates of any intracranial hemorrhage (RR, 1.94; 95% CI, 1.48-2.53) and symptomatic intracranial hemorrhage (RR, 1.73; 95% CI, 1.11-2.69). CONCLUSION: Endovascular thrombectomy (EVT) significantly improves neurological and functional outcomes in patients who present within 6 hours of stroke onset with ICA and proximal M1 occlusions, and ASPECTS scores ranging from 3 to 5, compared to medical therapy alone, with an increased risk of symptomatic intracranial hemorrhage.

2.
Nat Commun ; 15(1): 3633, 2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38684679

RESUMO

Various mechanical effects have been reported with molecular materials, yet organic crystals capable of multiple dynamic effects are rare, and at present, their performance is worse than some of the common actuators. Here, we report a confluence of different mechanical effects across three polymorphs of an organic crystal that can efficiently convert light into work. Upon photodimerization, acicular crystals of polymorph I display output work densities of about 0.06-3.94 kJ m-3, comparable to ceramic piezoelectric actuators. Prismatic crystals of the same form exhibit very high work densities of about 1.5-28.5 kJ m-3, values that are comparable to thermal actuators. Moreover, while crystals of polymorph II roll under the same conditions, crystals of polymorph III are not photochemically reactive; however, they are mechanically flexible. The results demonstrate that multiple and possibly combined mechanical effects can be anticipated even for a simple organic crystal.

3.
Nat Commun ; 14(1): 5751, 2023 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-37717049

RESUMO

The growing freshwater scarcity has caused increased use of membrane desalination of seawater as a relatively sustainable technology that promises to provide long-term solution for the increasingly water-stressed world. However, the currently used membranes for desalination on an industrial scale are inevitably prone to fouling that results in decreased flux and necessity for periodic chemical cleaning, and incur unacceptably high energy cost while also leaving an environmental footprint with unforeseeable long-term consequences. This extant problem requires an immediate shift to smart separation approaches with self-cleaning capability for enhanced efficiency and prolonged operational lifetime. Here, we describe a conceptually innovative approach to the design of smart membranes where a dynamic functionality is added to the surface layer of otherwise static membranes by incorporating stimuli-responsive organic crystals. We demonstrate a gating effect in the resulting smart dynamic membranes, whereby mechanical instability caused by rapid mechanical response of the crystals to heating slightly above room temperature activates the membrane and effectively removes the foulants, thereby increasing the mass transfer and extending its operational lifetime. The approach proposed here sets a platform for the development of a variety of energy-efficient hybrid membranes for water desalination and other separation processes that are devoid of fouling issues and circumvents the necessity of chemical cleaning operations.

4.
Chem Soc Rev ; 52(9): 3098-3169, 2023 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-37070570

RESUMO

In the last century, molecular crystals functioned predominantly as a means for determining the molecular structures via X-ray diffraction, albeit as the century came to a close the response of molecular crystals to electric, magnetic, and light fields revealed that the physical properties of molecular crystals were as rich as the diversity of molecules themselves. In this century, the mechanical properties of molecular crystals have continued to enhance our understanding of the colligative responses of weakly bound molecules to internal frustration and applied forces. Here, the authors review the main themes of research that have developed in recent decades, prefaced by an overview of the particular considerations that distinguish molecular crystals from traditional materials such as metals and ceramics. Many molecular crystals will deform themselves as they grow under some conditions. Whether they respond to intrinsic stress or external forces or interactions among the fields of growing crystals remains an open question. Photoreactivity in single crystals has been a leading theme in organic solid-state chemistry; however, the focus of research has been traditionally on reaction stereo- and regio-specificity. However, as light-induced chemistry builds stress in crystals anisotropically, all types of motions can be actuated. The correlation between photochemistry and the responses of single crystals-jumping, twisting, fracturing, delaminating, rocking, and rolling-has become a well-defined field of research in its own right: photomechanics. The advancement of our understanding requires theoretical and high-performance computations. Computational crystallography not only supports interpretations of mechanical responses, but predicts the responses itself. This requires the engagement of classical force-field based molecular dynamics simulations, density functional theory-based approaches, and the use of machine learning to divine patterns to which algorithms can be better suited than people. The integration of mechanics with the transport of electrons and photons is considered for practical applications in flexible organic electronics and photonics. Dynamic crystals that respond rapidly and reversibly to heat and light can function as switches and actuators. Progress in identifying efficient shape-shifting crystals is also discussed. Finally, the importance of mechanical properties to milling and tableting of pharmaceuticals in an industry still dominated by active ingredients composed of small molecule crystals is reviewed. A dearth of data on the strength, hardness, Young's modulus, and fracture toughness of molecular crystals underscores the need for refinement of measurement techniques and conceptual tools. The need for benchmark data is emphasized throughout.

5.
Angew Chem Int Ed Engl ; 62(9): e202217329, 2023 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-36575895

RESUMO

One of the typical haptic elements are natural hairy structures that animals and plants rely on for feedback. Although these hair sensors are an admirable inspiration, the development of active flow sensing components having low elastic moduli and high aspect ratios remains a challenge. Here, we report a new sensing approach based on a flexible, thin and optically transmissive organic crystal of high aspect ratio, which is stamped with fluorescent dye for tracking. When subjected to gas flow and exposed to laser, the crystal bends due to exerted pressure and acts as an optical flow (hair) sensor with low detection limit (≈1.578 m s-1 ) and fast response time (≈2.70 s). The air-flow-induced crystal deformation and flow dynamics response are modelled by finite element analysis. Due to having a simple design and being lightweight and mechanically robust this prototypical crystal hair-like sensor opens prospects for a new class of sensing devices ranging from wearable electronics to aeronautics.

6.
Nat Commun ; 13(1): 2823, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35595845

RESUMO

Dynamic organic crystals are rapidly gaining traction as a new class of smart materials for energy conversion, however, they are only capable of very small strokes (<12%) and most of them operate through energetically cost-prohibitive processes at high temperatures. We report on the exceptional performance of an organic actuating material with exceedingly large stroke that can reversibly convert energy into work around room temperature. When transitioning at 295-305 K on heating and at 265-275 K on cooling the ferroelectric crystals of guanidinium nitrate exert a linear stroke of 51%, the highest value observed with a reversible operation of an organic single crystal actuator. Their maximum force density is higher than electric cylinders, ceramic piezoactuators, and electrostatic actuators, and their work capacity is close to that of thermal actuators. This work demonstrates the hitherto untapped potential of ionic organic crystals for applications such as light-weight capacitors, dielectrics, ferroelectric tunnel junctions, and thermistors.

7.
Plants (Basel) ; 9(7)2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-32630736

RESUMO

Fungal storage rots like blue mould, grey mould, bull's eye rot, bitter rot and brown rot destroy large amounts of the harvested apple crop around the world. Application of fungicides is nowadays severely restricted in many countries and production systems, and these problems are therefore likely to increase. Considerable variation among apple cultivars in resistance/susceptibility has been reported, suggesting that efficient defence mechanisms can be selected for and used in plant breeding. These are, however, likely to vary between pathogens, since some fungi are mainly wound-mediated while others attack through lenticels or by infecting blossoms. Since mature fruits are considerably more susceptible than immature fruits, mechanisms involving fruit-ripening processes are likely to play an important role. Significant associations have been detected between the susceptibility to rots in harvested fruit and various fruit maturation-related traits like ripening time, fruit firmness at harvest and rate of fruit softening during storage, as well as fruit biochemical contents like acidity, sugars and polyphenols. Some sources of resistance to blue mould have been described, but more research is needed on the development of spore inoculation methods that produce reproducible data and can be used for large screenings, especially for lenticel-infecting fungi.

8.
J Sci Food Agric ; 96(6): 2161-9, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26147234

RESUMO

BACKGROUND: For health promotion and as part of natural plant protection, it might be of interest to increase the content of oleanolic acid (OA) and ursolic acid (UA) by biofortification in breeding programs, although the extent of the influence of genetic and environmental factors needs to be clarified. The objective of this study was to determine the effect of cultivar, sun exposure, storage, bruising and fungal infection on the OA and UA content in apple peel. RESULTS: Three apple cultivars with different ripening times--'Discovery' (early), 'Aroma' (middle) and 'Gloster' (late)--were investigated. The content of OA and UA was mainly influenced by cultivar and side subjected to sun exposure, and to a minor extent by storage and seasonal year. 'Gloster' had the highest OA and UA content of the investigated cultivars. OA and UA content on the shaded side was higher than that on the sun-exposed side in all three cultivars. Inoculation with Penicillium expansum did not have any consistent effect on OA or UA, except in a few cases where the levels decreased. CONCLUSION: OA and UA content can be increased by choice of cultivar in the breeding process and to some extent by cultural practice.


Assuntos
Frutas/química , Malus/metabolismo , Ácido Oleanólico/química , Penicillium/fisiologia , Luz Solar , Triterpenos/química , Armazenamento de Alimentos , Frutas/metabolismo , Frutas/microbiologia , Concentração de Íons de Hidrogênio , Malus/química , Malus/genética , Ácido Oleanólico/metabolismo , Fatores de Tempo , Triterpenos/metabolismo , Ácido Ursólico
9.
J Cross Cult Gerontol ; 30(1): 69-85, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25349019

RESUMO

The population of Malaysia is relatively young, due to this there is a dearth in research conducted among the elderly especially relating to depression. The aim of this study is to determine the prevalence and the predictors of severe depression among the elderly in Malaysia. A sample of 2005 older adults randomly selected from the Penang State government's list of elderly receiving aid participated in the study. The Geriatric Depression Scale was used to screen for depression. Socio-demographic, social support, disease, functional and other factors were looked at as possible predictor variables. The prevalence of severe depression was 19.2 %. Indians (aOR = 2.0), being married (aOR = 10.5), widowed & divorced (aOR = 5.2), having poor (aOR = 2.7) or moderate social support (aOR = 2.7), having no one (aOR = 2.9), relatives (aOR = 2.3) or religious figures & others (aOR = 1.9) as compared to a spouse as a source of emotional support, feeling extremely lonely (aOR = 3.4), not socially active (aOR = 2.3), cognitively impaired (aOR 2.5), activities limited due to illness or disability (aOR = 1.6) and poor sleep quality (aOR = 3.6) were significant predictor variables. The prevalence of severe depression was high. It is pertinent that older adults, especially those with risk factors identified in this study be screened for depression at every opportunity.


Assuntos
Depressão/epidemiologia , Atividades Cotidianas , Idoso , Estudos Transversais , Feminino , Avaliação Geriátrica , Humanos , Malásia/epidemiologia , Masculino , Pessoa de Meia-Idade , Exame Físico , Valor Preditivo dos Testes , Prevalência , Escalas de Graduação Psiquiátrica , Fatores de Risco , Apoio Social , Fatores Socioeconômicos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...