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1.
Nature ; 559(7712): 77-82, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29942075

RESUMO

Developing adaptive materials with geometries that change in response to external stimuli provides fundamental insights into the links between the physical forces involved and the resultant morphologies and creates a foundation for technologically relevant dynamic systems1,2. In particular, reconfigurable surface topography as a means to control interfacial properties3 has recently been explored using responsive gels4, shape-memory polymers5, liquid crystals6-8 and hybrid composites9-14, including magnetically active slippery surfaces12-14. However, these designs exhibit a limited range of topographical changes and thus a restricted scope of function. Here we introduce a hierarchical magneto-responsive composite surface, made by infiltrating a ferrofluid into a microstructured matrix (termed ferrofluid-containing liquid-infused porous surfaces, or FLIPS). We demonstrate various topographical reconfigurations at multiple length scales and a broad range of associated emergent behaviours. An applied magnetic-field gradient induces the movement of magnetic nanoparticles suspended in the ferrofluid, which leads to microscale flow of the ferrofluid first above and then within the microstructured surface. This redistribution changes the initially smooth surface of the ferrofluid (which is immobilized by the porous matrix through capillary forces) into various multiscale hierarchical topographies shaped by the size, arrangement and orientation of the confining microstructures in the magnetic field. We analyse the spatial and temporal dynamics of these reconfigurations theoretically and experimentally as a function of the balance between capillary and magnetic pressures15-19 and of the geometric anisotropy of the FLIPS system. Several interesting functions at three different length scales are demonstrated: self-assembly of colloidal particles at the micrometre scale; regulated flow of liquid droplets at the millimetre scale; and switchable adhesion and friction, liquid pumping and removal of biofilms at the centimetre scale. We envision that FLIPS could be used as part of integrated control systems for the manipulation and transport of matter, thermal management, microfluidics and fouling-release materials.

2.
BMC Med Inform Decis Mak ; 24(1): 145, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38811961

RESUMO

BACKGROUND: Nasal polyps and inverted papillomas often look similar. Clinically, it is difficult to distinguish the masses by endoscopic examination. Therefore, in this study, we aimed to develop a deep learning algorithm for computer-aided diagnosis of nasal endoscopic images, which may provide a more accurate clinical diagnosis before pathologic confirmation of the nasal masses. METHODS: By performing deep learning of nasal endoscope images, we evaluated our computer-aided diagnosis system's assessment ability for nasal polyps and inverted papilloma and the feasibility of their clinical application. We used curriculum learning pre-trained with patches of nasal endoscopic images and full-sized images. The proposed model's performance for classifying nasal polyps, inverted papilloma, and normal tissue was analyzed using five-fold cross-validation. RESULTS: The normal scores for our best-performing network were 0.9520 for recall, 0.7900 for precision, 0.8648 for F1-score, 0.97 for the area under the curve, and 0.8273 for accuracy. For nasal polyps, the best performance was 0.8162, 0.8496, 0.8409, 0.89, and 0.8273, respectively, for recall, precision, F1-score, area under the curve, and accuracy. Finally, for inverted papilloma, the best performance was obtained for recall, precision, F1-score, area under the curve, and accuracy values of 0.5172, 0.8125, 0.6122, 0.83, and 0.8273, respectively. CONCLUSION: Although there were some misclassifications, the results of gradient-weighted class activation mapping were generally consistent with the areas under the curve determined by otolaryngologists. These results suggest that the convolutional neural network is highly reliable in resolving lesion locations in nasal endoscopic images.


Assuntos
Aprendizado Profundo , Endoscopia , Cavidade Nasal , Pólipos Nasais , Humanos , Cavidade Nasal/diagnóstico por imagem , Cavidade Nasal/patologia , Pólipos Nasais/diagnóstico por imagem , Neoplasias Nasais/diagnóstico por imagem , Neoplasias Nasais/patologia , Papiloma Invertido/diagnóstico por imagem , Papiloma Invertido/patologia , Diagnóstico por Computador , Diagnóstico Diferencial , Masculino , Pessoa de Meia-Idade , Adulto
3.
Eur J Neurol ; 30(4): 911-919, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36692249

RESUMO

BACKGROUND: We aimed to investigate the incidence rate of Parkinson's disease dementia (PDD) according to age and disease duration by sex. Furthermore, we explored the effect of each cardiometabolic syndrome and depression on the incidence of PDD. METHODS: Using data from the Korean National Health Insurance Service, 79,622 patients with de novo Parkinson's disease (PD) aged ≥40 years between January 2002 and December 2010 were followed to December 2019. We analyzed the incidence of PDD according to age at PD diagnosis and disease duration. To determine cardiometabolic syndromes and depression that affected PDD, we used Fine and Gray competing regression after controlling for age and sex. RESULTS: During the 12.5-year follow-up period, the incidence of PDD increased with age at PD diagnosis (0.81-45.31 per 1000 person-years among those aged 40-44 and over 80 years, respectively) and longer disease duration (22.68 per 1000 person-years in 1-2 years to 34.16 per 1000 person-years in 15-16 years). Hypertension (subdistribution hazard ratio [SHR] = 1.11; 95% confidence interval [CI] 1.07-1.16), diabetes (SHR = 1.09; 95% CI 1.05-1.14), dyslipidemia (SHR = 1.15; 95% CI 1.11-1.20), and depression (SHR = 1.36; 95% CI 1.30-1.41) independently increased the risk for PDD. CONCLUSIONS: Our findings provide insights into cardiometabolic syndromes as modifiable risk factors for incident PDD. Furthermore, our results will help in designing public health policies with respect to controlling cardiometabolic syndromes and depression to prevent incident PDD in patients with PD.


Assuntos
Doença de Alzheimer , Demência , Síndrome Metabólica , Doença de Parkinson , Humanos , Doença de Parkinson/epidemiologia , Demência/epidemiologia , Seguimentos , Síndrome Metabólica/complicações , Depressão , Doença de Alzheimer/complicações
4.
J Surg Res ; 291: 116-123, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37356340

RESUMO

INTRODUCTION: Vascular reconstruction requires technical expertise and is often time consuming. As a novel alternative to traditional hand-sewn vascular anastomoses, the VasoLock (VL), is a nonabsorbable, sutureless anastomosis device with traction anchors designed to hold free artery ends together. These anchors do not penetrate the vessel wall but adhere by leveraging the elasticity of the vessels to fasten blood vessels together. This pilot study assesses the performance and patency of this novel device in a porcine model of femoral artery injury. METHODS: Female swine (n = 7) underwent femoral artery exposure for a total of 10 VL implanted. Study animals underwent hemodilution to a target hematocrit of 15% and ROTEM was used to assess coagulopathy, followed by an arterial injury via transection. The VL was inserted without any sutures. Flow-probe monitors were positioned proximal and distal to the device and flow rates were measured continuously for a total of 90 min. Flow was analyzed and presented as a ratio of distal to proximal flow with the slope of this ratio across time subsequently determined. Angiographic assessment was completed to evaluate for patency and technical complications after 90 min of implant. RESULTS: The average animal weight was 44.1 ± 3.2 kg. The average mean arterial pressure at the time of implant was 51.2 ± 7.8 mmHg, median heart rate was 77.4 (IQR = 77.25-157.4) beats per minute, and average temperature was 36.1 ± 1.5°C. The baseline hematocrit was 13.5 ± 3.0%, average pH was 7.20 ± 0.1, average clotting time was 154.1 ± 58.7 s and average clot formation time was 103.4 ± 10.9 s all demonstrating the acidotic, hypothermic, and coagulopathic state of the swine at the time of insertion. During the 90-min observation period, the average flow gradient identified across the VL was 0.99 ± 0.24, indicating no significant change in flow across the VL. The average slope of the gradients was 0.0005 (P = 0.22), suggesting the ratio of proximal and distal flow did not change over the 90 min. Following 90 min of dwell time, all VL were patent without technical complication. Angiographic assessment at 90 min demonstrated no evidence of dissection, device migration, arterial extravasation, or thromboembolism with any of the 10 devices. CONCLUSIONS: This pilot study demonstrated technical feasibility of the novel VL device over a 90-min observation period. All VL were patent and no negative events or complications were identified. This technology demonstrated significant promise in a coagulopathic state: additional investigation, involving long-term survival, is warranted for further validation.


Assuntos
Artéria Femoral , Feminino , Animais , Suínos , Estudo de Prova de Conceito , Projetos Piloto , Grau de Desobstrução Vascular , Anastomose Cirúrgica , Artéria Femoral/cirurgia
5.
Eur J Neurol ; 29(2): 413-421, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34716964

RESUMO

BACKGROUND AND PURPOSE: Subcortical vascular cognitive impairment (SVCI) is characterized by the presence of cerebral small vessel disease (CSVD) markers. Some SVCI patients also show Alzheimer's disease and cerebral amyloid angiopathy markers. However, the effects of these imaging markers on long-term clinical outcomes have not yet been established. The present study, therefore, aimed to determine how these imaging markers influence functional disability and/or mortality. METHODS: We recruited 194 participants with SVCI from the memory clinic and followed them up. All participants underwent brain magnetic resonance imaging at baseline, and 177 (91.2%) participants underwent beta-amyloid (Aß) positron emission tomography. We examined the occurrence of ischemic or hemorrhagic strokes. We also evaluated functional disability and mortality using the modified Rankin scale. To determine the effects of imaging markers on functional disability or mortality, we used Fine and Gray competing regression or Cox regression analysis. RESULTS: During a 8.6-year follow-up period, 46 of 194 patients (23.7%) experienced a stroke, 110 patients (56.7%) developed functional disabilities and 75 (38.6%) died. Aß positivity (subdistribution hazard ratio [SHR] = 2.73), greater white matter hyperintensity (WMH) volume (SHR = 3.11) and ≥3 microbleeds (SHR = 2.29) at baseline were independent predictors of functional disability regardless of the occurrence of stroke. Greater WMH volume (hazard ratio = 2.07) was an independent predictor of mortality. CONCLUSIONS: Our findings suggest that diverse imaging markers may predict long-term functional disability and mortality in patients with SVCI, which in turn may provide clinicians with a more insightful understanding of the long-term outcomes of SVCI.


Assuntos
Doença de Alzheimer , Angiopatia Amiloide Cerebral , Disfunção Cognitiva , Peptídeos beta-Amiloides , Disfunção Cognitiva/diagnóstico por imagem , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética
6.
Clin Auton Res ; 32(1): 43-50, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34841452

RESUMO

PURPOSE: Orthostatic hypotension (OH) is an associative or causative factor of cognitive impairment in Parkinson's disease (PD). However, the association between mild cognitive impairment (MCI) and neurogenic OH directly associated with the presence of alpha-synuclein in PD remains unclear. We aimed to evaluate the relationship between MCI and neurogenic OH in patients with de novo PD. We also investigated the patterns of neuropsychological performance according to neurogenic OH. METHODS: A total of 456 patients with PD-normal cognition (PD-NC, n = 204) or PD-MCI (n = 252) were recruited from multiple centers in Korea. All patients underwent comprehensive neuropsychological tests and tilt-table tests to evaluate cognitive function and neurogenic OH. We used logistic regression analysis and multivariate analysis of covariance to determine the association between MCI and neurogenic OH and the pattern of neuropsychological performance according to neurogenic OH. RESULTS: Neurogenic OH (odds ratio = 3.66, 95% confidence interval 2.06 to 6.47) was independently associated with MCI in patients with de novo PD, regardless of orthostatic symptoms, while nonneurogenic OH was not. Patients with PD with neurogenic OH exhibited worse performance in frontal-executive function and visual memory function than those without neurogenic OH. CONCLUSION: Our findings provide insight into neurogenic OH as an important clinical factor with cognitive impairment in individuals with PD and vice versa. Therefore, the evaluation of cognitive function is necessary in PD patients with neurogenic OH.


Assuntos
Disfunção Cognitiva , Hipotensão Ortostática , Doença de Parkinson , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/etiologia , Função Executiva , Humanos , Hipotensão Ortostática/complicações , Testes Neuropsicológicos , Doença de Parkinson/complicações
7.
Sensors (Basel) ; 22(14)2022 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-35890946

RESUMO

Carbon−polymer composite-based pressure sensors have many attractive features, including low cost, easy integration, and facile fabrication. Previous studies on carbon−polymer composite sensors focused on very high sensitivities for low pressure ranges (10 s of kPa), which saturate quickly at higher pressures and thus are ill-suited to measure the high pressure ranges found in various applications, including those in underwater (>1 atm, 101 kPa) and industrial environments. Current sensors designed for high pressure environments are often difficult to fabricate, expensive, and, similarly to their low-pressure counterparts, have a narrow sensing range. To address these issues, this work reports the design, synthesis, characterization, and analysis of high-pressure TPU-MWCNT based composite sensors, which detect pressures from 0.5 MPa (4.9 atm) to over 10 MPa (98.7 atm). In this study, the typical approach to improve sensitivity by increasing conductive additive concentration was found to decrease sensor performance at elevated pressures. It is shown that a better approach to elevated pressure sensitivity is to increase sensor response range by decreasing the MWCNT weight percentage, which improves sensing range and resolution. Such sensors can be useful for measuring high pressures in many industrial (e.g., manipulator feedback), automotive (e.g., damping elements, bushings), and underwater (e.g., depth sensors) applications.


Assuntos
Nanotubos de Carbono , Polímeros , Condutividade Elétrica
8.
Eur J Nucl Med Mol Imaging ; 49(1): 321-330, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34328533

RESUMO

PURPOSE: In this study, we used machine learning to develop a new method derived from a ligand-independent amyloid (Aß) positron emission tomography (PET) classifier to harmonise different Aß ligands. METHODS: We obtained 107 paired 18F-florbetaben (FBB) and 18F-flutemetamol (FMM) PET images at the Samsung Medical Centre. To apply the method to FMM ligand, we transferred the previously developed FBB PET classifier to test similar features from the FMM PET images for application to FMM, which in turn developed a ligand-independent Aß PET classifier. We explored the concordance rates of our classifier in detecting cortical and striatal Aß positivity. We investigated the correlation of machine learning-based cortical tracer uptake (ML-CTU) values quantified by the classifier between FBB and FMM. RESULTS: This classifier achieved high classification accuracy (area under the curve = 0.958) even with different Aß PET ligands. In addition, the concordance rate of FBB and FMM using the classifier (87.5%) was good to excellent, which seemed to be higher than that in visual assessment (82.7%) and lower than that in standardised uptake value ratio cut-off categorisation (93.3%). FBB and FMM ML-CTU values were highly correlated with each other (R = 0.903). CONCLUSION: Our findings suggested that our novel classifier may harmonise FBB and FMM ligands in the clinical setting which in turn facilitate the biomarker-guided diagnosis and trials of anti-Aß treatment in the research field.


Assuntos
Doença de Alzheimer , Doença de Alzheimer/diagnóstico por imagem , Peptídeos beta-Amiloides/metabolismo , Compostos de Anilina , Encéfalo/metabolismo , Humanos , Ligantes , Aprendizado de Máquina , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X
9.
Scr Mater ; 422021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38487257

RESUMO

The elastic response of homogeneous isotropic materials is most commonly represented by their Young's modulus (E), but geometric variability associated with additive manufacturing results in materials that are neither homogeneous nor isotropic. Here we investigated methods to estimate the effective elastic modulus (Eeff) of samples fabricated by fused filament fabrication. We conducted finite element analysis (FEA) on printed samples based on material properties and CT-scanned geometries. The analysis revealed how the layer structure of a specimen altered the internal stress distribution and the resulting Eeff. We also investigated different empirical methods to estimate Eeff as guides. We envision the findings from our study can provide guidelines for modulus estimation of as-printed specimens, with the potential of applying to other extrusion-based additive manufacturing technologies.

10.
Stroke ; 51(12): 3600-3607, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33198580

RESUMO

BACKGROUND AND PURPOSE: We aimed to determine whether lobar cerebellar microbleeds or concomitant lobar cerebellar and deep microbleeds, in the presence of lobar cerebral microbleeds, attribute to underlying advanced cerebral amyloid angiopathy pathology or hypertensive arteriopathy. METHODS: We categorized 71 patients with suspected cerebral amyloid angiopathy markers (regardless of the presence of deep and cerebellar microbleeds) into 4 groups according to microbleed distribution: L (strictly lobar cerebral, n=33), L/LCbll (strictly lobar cerebral and strictly lobar cerebellar microbleeds, n=13), L/Cbll/D (lobar, cerebellar, and deep microbleeds, n=17), and L/D (lobar and deep, n=8). We additionally categorized patients with cerebellar microbleeds into 2 groups according to dentate nucleus involvement: strictly lobar cerebellar (n=16) and dentate (n=14). We then compared clinical characteristics, Aß (amyloid-ß) positivity on PET (positron emission tomography), magnetic resonance imaging cerebral amyloid angiopathy markers, and cerebral small vessel disease burden among groups. RESULTS: The frequency of Aß positivity was higher in the L and L/LCbll groups (81.8% and 84.6%) than in the L/Cbll/D and L/D groups (37.5% and 29.4%; P<0.001), while lacune numbers were lower in the L and L/LCbll groups (1.7±3.3 and 1.7±2.6) than in the L/Cbll/D and L/D groups (8.0±10.3 and 13.4±17.7, P=0.001). The L/LCbll group had more lobar cerebral microbleeds than the L group (93.2±121.8 versus 38.0±40.8, P=0.047). The lobar cerebellar group had a higher Aß positivity (75% versus 28.6%, P=0.011) and lower lacune number (2.3±3.7 versus 8.6±1.2, P=0.041) than the dentate group. CONCLUSIONS: Strictly lobar cerebral and cerebellar microbleeds are related to cerebral amyloid angiopathy, whereas any combination of concurrent lobar and deep microbleeds suggest hypertensive angiopathy regardless of cerebral or cerebellar compartments.


Assuntos
Doenças Cerebelares/diagnóstico por imagem , Angiopatia Amiloide Cerebral/diagnóstico por imagem , Hemorragia Cerebral/diagnóstico por imagem , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Disfunção Cognitiva/diagnóstico por imagem , Demência/diagnóstico por imagem , Hemorragias Intracranianas/diagnóstico por imagem , Doenças Talâmicas/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Compostos de Anilina , Hemorragia dos Gânglios da Base/diagnóstico por imagem , Benzotiazóis , Núcleos Cerebelares/diagnóstico por imagem , Cerebelo/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Estilbenos , Tiazóis
11.
Nature ; 573(7773): 198-199, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31511680
12.
Proc Natl Acad Sci U S A ; 114(44): 11639-11644, 2017 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-29078275

RESUMO

Although the human visual system is remarkable at perceiving and interpreting motions, it has limited sensitivity, and we cannot see motions that are smaller than some threshold. Although difficult to visualize, tiny motions below this threshold are important and can reveal physical mechanisms, or be precursors to large motions in the case of mechanical failure. Here, we present a "motion microscope," a computational tool that quantifies tiny motions in videos and then visualizes them by producing a new video in which the motions are made large enough to see. Three scientific visualizations are shown, spanning macroscopic to nanoscopic length scales. They are the resonant vibrations of a bridge demonstrating simultaneous spatial and temporal modal analysis, micrometer vibrations of a metamaterial demonstrating wave propagation through an elastic matrix with embedded resonating units, and nanometer motions of an extracellular tissue found in the inner ear demonstrating a mechanism of frequency separation in hearing. In these instances, the motion microscope uncovers hidden dynamics over a variety of length scales, leading to the discovery of previously unknown phenomena.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Microscopia/métodos , Gravação em Vídeo , Lasers , Movimento (Física)
13.
J Korean Med Sci ; 35(44): e361, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-33200589

RESUMO

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers are increasingly used in clinical practice for the diagnosis of Alzheimer's disease (AD). We aimed to 1) determine cutoff values of CSF biomarkers for AD, 2) investigate their clinical utility by estimating a concordance with amyloid positron emission tomography (PET), and 3) apply ATN (amyloid/tau/neurodegeneration) classification based on CSF results. METHODS: We performed CSF analysis in 51 normal controls (NC), 23 mild cognitive impairment (MCI) and 65 AD dementia (ADD) patients at the Samsung Medical Center in Korea. We attempted to develop cutoff of CSF biomarkers for differentiating ADD from NC using receiver operating characteristic analysis. We also investigated a concordance between CSF and amyloid PET results and applied ATN classification scheme based on CSF biomarker abnormalities to characterize our participants. RESULTS: CSF Aß42, total tau (t-tau) and phosphorylated tau (p-tau) significantly differed across the three groups. The area under curve for the differentiation between NC and ADD was highest in t-tau/Aß42 (0.994) followed by p-tau/Aß42 (0.963), Aß42 (0.960), t-tau (0.918), and p-tau (0.684). The concordance rate between CSF Aß42 and amyloid PET results was 92%. Finally, ATN classification based on CSF biomarker abnormalities led to a majority of NC categorized into A-T-N-(73%), MCI as A+T-N-(30%)/A+T+N+(26%), and ADD as A+T+N+(57%). CONCLUSION: CSF biomarkers had high sensitivity and specificity in differentiating ADD from NC and were as accurate as amyloid PET. The ATN subtypes based on CSF biomarkers may further serve to predict the prognosis.


Assuntos
Doença de Alzheimer/diagnóstico , Biomarcadores/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/classificação , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Área Sob a Curva , Estudos de Casos e Controles , Disfunção Cognitiva/classificação , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos/líquido cefalorraquidiano , Tomografia por Emissão de Pósitrons , Curva ROC , Índice de Gravidade de Doença , Proteínas tau/líquido cefalorraquidiano
14.
Biophys J ; 117(5): 817-828, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31421835

RESUMO

Measurements of the mechanical response of biological cells are critical for understanding injury and disease, for developing diagnostic tools, and for computational models in mechanobiology. Although it is well known that cells are sensitive to the topography of their microenvironment, the current paradigm in mechanical testing of adherent cells is mostly limited to specimens grown on flat two-dimensional substrates. In this study, we introduce a technique in which cellular indentation via optical trapping is performed on cells at a high spatial resolution to obtain their regional mechanical properties while they exist in a more favorable three-dimensional microenvironment. We combine our approach with nonlinear contact mechanics theory to consider the effects of a large deformation. This allows us to probe length scales that are relevant for obtaining overall cell stiffness values. The experimental results herein provide the hyperelastic material properties at both high (∼100 s-1) and low (∼1-10 s-1) strain rates of murine central nervous system glial cells. The limitations due to possible misalignment of the indenter in the three-dimensional space are examined using a computational model.


Assuntos
Microambiente Celular , Animais , Fenômenos Biomecânicos , Células Cultivadas , Camundongos , Pinças Ópticas , Estresse Mecânico , Alicerces Teciduais/química
16.
Phys Rev Lett ; 118(8): 084302, 2017 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-28282189

RESUMO

We demonstrate both numerically and experimentally that geometric frustration in two-dimensional periodic acoustic networks consisting of arrays of narrow air channels can be harnessed to form band gaps (ranges of frequency in which the waves cannot propagate in any direction through the system). While resonant standing wave modes and interferences are ubiquitous in all the analyzed network geometries, we show that they give rise to band gaps only in the geometrically frustrated ones (i.e., those comprising of triangles and pentagons). Our results not only reveal a new mechanism based on geometric frustration to suppress the propagation of pressure waves in specific frequency ranges but also open avenues for the design of a new generation of smart systems that control and manipulate sound and vibrations.

17.
BMC Gastroenterol ; 17(1): 69, 2017 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-28558658

RESUMO

BACKGROUND: Endoscopic papillectomy (EP) is reported to be a relatively safe and reliable procedure for complete resection of ampullary neoplasms. The aim of this study was to evaluate the therapeutic outcomes and complications of EP for ampullary neoplasms. METHODS: A retrospective multicenter study was conducted with 5 participating centers from January 2007 to July 2014. A total of 104 patients who underwent EP for ampullary neoplasms were reviewed retrospectively. EP was performed by snare resection with or without submucosal lifting of the lesion. RESULTS: The mean age of patients was 60.5 ± 12.1 years, and the male-to-female ratio was 2.0:1. En bloc resection was possible in 94 patients (90.3%). A biliary and a pancreatic stent were placed after EP in 42 patients and in 60 patients, respectively. A pathologically incomplete resection was noted in 11 cases (10.6%), and 5 of these patients were treated with additional endoscopic procedure. Histology of resected specimens was as follows: low grade adenoma (43.2%), high grade adenoma (14.4%), adenocarcinoma (16.3%), hyperplastic polyp (7.7%), and others (18.4%). Of the 75 cases with low grade adenoma on biopsy specimen, 21.3% turned out to have high grade adenoma (12%) or adenocarcinoma (9.3%). Procedure-related complications occurred in 33 patients (31.7%); bleeding (18 cases, 17.3%), pancreatitis (16 cases, 15.4%), and perforation (8 cases, 7.7%). Pre-EP ERCP, saline lifting, sphincterotomy, biliary stenting, pancreatic stenting, specimen size, and cauterization were not related to post EP complications. Surgery was performed in 6 cases with pathological incomplete resection and 2 cases with complications after EP, and there were 2 cases of mortality due to complications. During follow-up endoscopy after initial success of EP, remnant tumors were found in 7 patients, one of whom underwent surgery and the others were treated endoscopically. Consequently, the overall endoscopic success rate of EP was 89.4%. CONCLUSIONS: Endoscopic papillectomy appears to be an effective treatment for ampullary neoplasms, and can be considered as an alternative to surgery. However, relatively high risk of procedure related complications is a problem that must be considered.


Assuntos
Ampola Hepatopancreática/cirurgia , Neoplasias do Ducto Colédoco/cirurgia , Esfinterotomia Endoscópica , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Estudos Retrospectivos , Esfinterotomia Endoscópica/efeitos adversos , Resultado do Tratamento
18.
Nature ; 477(7365): 443-7, 2011 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-21938066

RESUMO

Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging. Inspirations from natural nonwetting structures, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air-liquid interface. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis, failure under pressure and upon physical damage, inability to self-heal and high production cost. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach-inspired by Nepenthes pitcher plants-is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert 'slippery' interface. This surface outperforms its natural counterparts and state-of-the-art synthetic liquid-repellent surfaces in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1-1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.


Assuntos
Materiais Biomiméticos/química , Lubrificantes/química , Magnoliopsida/química , Pressão , Propriedades de Superfície , Molhabilidade , Animais , Formigas/fisiologia , Sangue , Hidrocarbonetos/química , Gelo , Lotus/anatomia & histologia , Lotus/química , Lubrificantes/farmacologia , Lubrificação , Magnoliopsida/anatomia & histologia , Nanoestruturas , Petróleo , Porosidade , Propriedades de Superfície/efeitos dos fármacos , Água/química
19.
Surg Endosc ; 30(4): 1599-606, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26194250

RESUMO

BACKGROUND: The purpose of this study was to evaluate postoperative voice outcomes and functional parameters in total thyroidectomy via a transaxillary (TA) approach. METHODS: Seventy-six patients who underwent total thyroidectomy via a TA approach (TA group) were included. A total of 204 patients who underwent conventional open total thyroidectomy (conventional group) in the same time period were analyzed as a control group. All patients underwent prospective functional evaluations before surgery and at 1 week and 1, 3, 6, and 12 months postoperatively using a comprehensive battery of functional assessments. RESULTS: There was no conversion to conventional open thyroidectomy in the TA group. Operation time and the amount of drainage were significantly higher in the TA group than in the conventional group (p < 0.001 and p = 0.033, respectively), while vocal cord paralysis, hypoparathyroidism, and hematoma were not different among two groups (p = 0.215, 0.290, and 0.385, respectively). Regarding GRBAS, the TA group showed a more aggravated tendency postoperatively, although statistical significance was attained only at postoperative 6 months (p = 0.043). The voice handicap index abruptly increased postoperatively in the TA group, showing significant differences with the conventional group at postoperative 1 week and 1 month (p < 0.001 and p = 0.001, respectively). Fundamental frequency and maximal vocal pitch did not significantly change postoperatively in either group. The conventional group showed a more rapid decline in pain than the TA group, and paresthesias on the neck and chest were more aggravated in the TA group during the early postoperative period. The dysphagia handicap index was higher in the TA group, while cosmesis was better in the TA group at all postoperative periods. CONCLUSIONS: Although cosmetic outcome was better with the TA approach, the longer operation time, aggravated subjective voice outcomes, paresthesia, and swallowing function need to be considered in selecting the operative approach.


Assuntos
Tireoidectomia/métodos , Adulto , Axila , Estudos de Casos e Controles , Estética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Parestesia/etiologia , Estudos Prospectivos , Neoplasias da Glândula Tireoide/cirurgia , Qualidade da Voz
20.
Stroke ; 45(6): 1849-52, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24803594

RESUMO

BACKGROUND AND PURPOSE: The objective of this study was to investigate the potential benefits of statin therapy on mortality and stroke recurrence after cardioembolic stroke. METHODS: In this retrospective observational study, we analyzed data from 535 patients with first-ever cardioembolic stroke. Patients were classified into nonstatin, low-potency statin, and high-potency statin groups. The primary outcomes were time to mortality and time to recurrent stroke. RESULTS: The mean duration of follow-up was 22.2 months. The cumulative mortality rate was 7% at the end of the first year and 10% at the end of the third year. Statin therapy was independently associated with reduced mortality (hazard ratio, 0.237; 95% confidence interval, 0.080-0.703 for nonstatin versus low-potency statin; hazard ratio, 0.158; 95% confidence interval, 0.037-0.686 for nonstatin versus high-potency statin). Statin treatment did not affect the incidence of recurrent stroke in patients with cardioembolic stroke. CONCLUSIONS: Statin therapy could be associated with reduced mortality in patients with cardioembolic stroke.


Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Embolia Intracraniana/tratamento farmacológico , Embolia Intracraniana/mortalidade , Acidente Vascular Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/mortalidade , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Masculino , Estudos Retrospectivos , Taxa de Sobrevida
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