Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Eur Radiol ; 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-32040729

RESUMO

OBJECTIVES: To evaluate risk factors for prevalence and progression of aortic valve calcification (AVC) in lung cancer screening participants and also to assess the sensitivity and reliability of visual AVCs on low-dose CT (LDCT) for predicting aortic stenosis (AS) in high-risk smokers. METHODS: We reviewed 1225 consecutive participants in annual LDCT screening for lung cancer at the Mount Sinai Hospital between 2010 and 2017. Sensitivity and specificity of moderate/severe AVC score on LDCT to identify AS on echocardiogram were calculated for 126 participants who had both within 12 months. Using regression analyses, risk factors for AVC at baseline, for progression, and for new AVC on annual rounds of screening were identified. Reliability of AVC assessment on LDCT was assessed by comparing visual AVC scores (1) with standard-dose, electrocardiography (ECG)-gated CT for 31 participants who had both within 12 months and (2) with Agatston scores of 1225 participants and by determining (3) the intra-reader agreement of 1225 participants. RESULTS: Visual AVC scores on LDCT had substantial agreement with the severity of AS on echocardiography and substantial inter-observer and excellent intra-observer agreement. Sensitivity and specificity of moderate/severe visual AVC scores for moderate/severe AS on echocardiogram were 100% and 94%, respectively. Significant predictors for baseline AVC were male sex (OR = 2.52), age (OR10 years = 2.87), and coronary artery calcification score (OR = 1.18), the significant predictor for AVC progression after baseline was pack-years of smoking (HR10 packyears = 1.14), and significant predictors for new AVC on annual LDCT were male sex (HR = 1.51), age (HR10 years = 2.17), CAC (HR = 1.09)  and BMI (HR = 1.06). CONCLUSIONS: AVC scores on LDCT should be documented, especially in lung cancer screening program. KEY POINTS: • LDCT screening for lung cancer provides an opportunity to identify lung cancer and cardiovascular disease in asymptomatic smokers. • Visual aortic valve calcification scores could be reliably evaluated on LDCT and had substantial agreement with the severity of aortic valve stenosis on echocardiography. • Sensitivity and specificity of moderate/severe visual AVC scores on LDCT for moderate/severe AS on echocardiogram were 100% and 94%, respectively.

2.
Med Sci Monit ; 25: 8260-8268, 2019 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-31678984

RESUMO

BACKGROUND The association between serum vitamin D level and vertebral fracture (VFx) remains controversial. The purpose of this study was to determine whether serum 25-hydroxy vitamin D (25(OH)D) level is associated with osteoporotic thoracolumbar junction VFx in elderly patients. MATERIAL AND METHODS From Jan 2013 to Dec 2017, this retrospective case-control study included 534 patients with primary osteoporotic thoracolumbar junction VFx (T10-L2) and 569 elderly orthopedic patients with back pain (without osteoporotic VFx) as controls. Serum 25(OH)D levels were measured and the association with osteoporotic VFx was analyzed. Other clinical data, including BMI, comorbidities, and bone mineral density (BMD), were also collected and compared between these 2 groups. RESULTS It was shown that 25(OH)D levels were significantly lower in patients with T10-L2 VFx than in control patients. Among 534 VFx patients, 417 (78.1%) patients showed grade 2-3 fracture. Serum 25(OH)D levels were significantly related to affected vertebral numbers and VFx severities. The VFx risk was 28% lower (OR=0.72, 95% CI 0.62-0.83) per increased SD in serum 25(OH)D. Compared with the 1st quartile (mean 25(OH)D: 29.67±6.18 nmol/L), the VFx risk was significantly lower in the 3rd (mean 25(OH)D: 60.91±5.12nmol/L) and 4th quartiles (mean 25(OH)D: 103.3±44.21nmol/L), but not in the 2nd quartile (mean 25(OH)D: 45.40±3.95 nmol/L). In contrast, the VFx risk was significantly increased in the 1st quartile (OR=1.87, 95% CI 1.42-2.45) compared with the 2nd-4th quartiles. CONCLUSIONS Vitamin D deficiency/insufficiency was associated with risk of osteoporotic thoracolumbar junction vertebral fractures in elderly patients.

3.
Se Pu ; 37(11): 1157-1161, 2019 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-31642267

RESUMO

A method using ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the determination of nine B vitamins in peptone. The samples were extracted with water. The analytes were separated on a Syncronis C18 column (100 mm×2.1 mm, 1.7 µm). The nine B vitamins were detected by ESI-MS/MS under the multiple reaction monitoring (MRM) mode, and the analysis was completed in 8 min. Quantification analysis was performed by using the external standard method. The correlation coefficients (R2) of the nine B vitamins in their linear ranges were greater than 0.999. The limits of detection were 0.09-1.67 µg/L. The relative standard deviations of the method were less than 3% (n=6). The mean recoveries of the nine B vitamins were 80.2%-103.9% at different spiked levels. The method is simple, accurate and sensitive, and is suitable for the determination of the nine B vitamins in peptone.


Assuntos
Peptonas/química , Complexo Vitamínico B/análise , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas em Tandem
4.
Appl Opt ; 58(26): 7035-7041, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31503972

RESUMO

This paper introduces radiative cooling metamaterial use in engineering thermal radiation based on metal-multi-dielectric-metal (MMDM) structure. The measured average absorption of the MMDM from 15° to 75° in the "atmosphere window" is 0.81, and the absorption range of the structure hardly changes with the incident angles. Without considering solar radiation, at the thermal conductivity of 6.9 W·m-2·K-1, the surface temperature is 10.8°C lower than the ambient temperature (300 K), and the cooling power is 102 W·m-2. Importantly, when the surface temperature is higher than the ambient temperature, this radiative cooler can lower the surface temperature in engineering thermal radiation with a higher thermal conductivity at the same cooling power.

5.
Polymers (Basel) ; 11(7)2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31323830

RESUMO

A passive radiative cooling method has a significant influence on thermal management applications because it can cool without any energy input. This work both experimentally and theoretically demonstrates a multilayer thin film structure with high solar reflectance, which can be applied to passive daytime radiative cooling. The combination of physical vapor deposition and spin-coating prepared the samples, which were also characterized experimentally by spectrometers. On-site measured results show that the emitter can effectively achieve daytime radiative cooling, and the cooling performance can be further improved with the increase of the ambient air temperature. When the emitter is exposed to direct solar radiation (AM1.5) of about 880 W/m2 on a rooftop under dry air conditions, it can achieve an average temperature reduction of about 12.6 °C from the ambient air temperature with nonradiative heat transfer (11 a.m.-1 p.m.). Theoretical simulations reveal that the emitter can still have a certain cooling performance in the presence of significant nonradiative heat exchange and nonideal atmospheric conditions. The influence of ambient air temperature on the cooling performance of the emitter is also theoretically analyzed.

6.
Water Res ; 163: 114912, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31362211

RESUMO

Zero valent iron (ZVI) activating peroxydisulfate (PDS) was demonstrated to be effective in improving the dewaterability of anaerobically digested sludge (ADS). However, details of how ZVI/PDS enhances the dewaterability remain largely unknown. This work therefore aims to reveal the facts of what happen in ZVI/PDS involved ADS systems. Experimental results showed that ZVI/PDS treatment remarkably improved the dewaterability of ADS, with the minimal normalized capillary suction time of 8.6 ±â€¯0.5 s L/g·VSS being obtained at the dosages of 2 g/g TSS ZVI and 0.5 g/g TSS PDS, which was 42.5% of that in the control. In this case, 71.2% ±â€¯1.8% of water content (press filtration) was measured, which was 16.9% lower than that determined in the control. The mechanism investigations showed that ZVI activating PDS produced substantially reactive species, i.e., SO4•- and •OH, and these strong oxidative radicals decreased surface negative charges of ADS flocs, caused disruption of extracellular polymeric substances (EPS) and release of intracellular substances, and changed the secondary structure of proteins. Additionally, the products of ZVI oxidation, i.e., Fe2+ and Fe3+, were effective flocculants, thus their generation benefited the coagulation of ADS flocs through compressing double electric layers and neutralizing negative charges of sludge colloidal particles. As a result, the flocculability, hydrophobicity, and flowability of ADS were enhanced, but the bound water content, fractal dimension, and viscosity of ADS were decreased, which were responsible for the improvement of dewaterability. Further analyses exhibited that the contributions of these major contributors were different, and their contributions to the dewaterability improvement were in the order of SO4·- > ·OH > Fe2+/Fe3+. It was also found that ZVI/PDS treatment enhanced the degradation of recalcitrant organics, inactivation of the fecal coliforms, and mitigation of the toxicity of heavy metals in the dewatered sludge, which were beneficial to its land application.


Assuntos
Ferro , Esgotos , Filtração , Oxirredução , Água
7.
Radiology ; 286(2): 502-511, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29206594

RESUMO

Purpose To assess the diagnostic accuracy of magnetic resonance (MR) imaging for differentiating stage T1 or lower tumors from stage T2 or higher tumors and to analyze the influence of different imaging protocols in patients with bladder cancer. Materials and Methods A systematic literature search for original diagnostic studies was performed in PubMed, Medline, the Cochrane Library, and Web of Science. The methodologic quality of each study was evaluated by two independent reviewers who used the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Data necessary to complete 2 × 2 tables were obtained, and patient, study, and imaging characteristics were extracted. Statistical analysis included data pooling, heterogeneity testing, sensitivity analyses, and forest plot construction. Results Seventeen studies (1449 patients with bladder cancer) could be analyzed. The pooled sensitivity and specificity of MR imaging were 0.90 (95% confidence interval [CI]: 0.83, 0.94) and 0.88 (95% CI: 0.77, 0.94), respectively, for differentiating tumors staged T1 or lower from those staged T2 or higher. Diffusion-weighted imaging and use of higher field strengths (3 T) improved sensitivity (0.92; 95% CI: 0.86, 0.96) and specificity (0.96; 95% CI: 0.93, 0.98). Conclusion This meta-analysis demonstrated high diagnostic performance of MR imaging for differentiating T1 or lower tumors from T2 or higher tumors in patients with bladder cancer. Higher field strength (3 T) and the use of diffusion-weighted imaging can slightly help improve sensitivity and specificity. © RSNA, 2017.


Assuntos
Neoplasias da Bexiga Urinária/patologia , Humanos , Imagem por Ressonância Magnética/normas , Estadiamento de Neoplasias , Curva ROC , Sensibilidade e Especificidade
8.
J Magn Reson Imaging ; 47(2): 391-400, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28640538

RESUMO

PURPOSE: To evaluate the utility of the whole-lesion histogram apparent diffusion coefficient (ADC) for characterizing the heterogeneity of mucinous breast carcinoma (MBC) and to determine which ADC metrics may help to best differentiate subtypes of MBC. MATERIALS AND METHODS: This retrospective study involved 52 MBC patients, including 37 pure MBC (PMBC) and 15 mixed MBC (MMBC). The PMBC patients were subtyped into PMBC-A (20 cases) and PMBC-B (17 cases) groups. All patients underwent preoperative diffusion-weighted imaging (DWI) at 1.5T and the whole-lesion ADC assessments were generated. Histogram-derived ADC parameters were compared between PMBC vs. MMBC and PMBC-A vs. PMBC-B, and receiver operating characteristic (ROC) curve analysis was used to determine optimal histogram parameters for differentiating these groups. RESULTS: The PMBC group exhibited significantly higher ADC values for the mean (P = 0.004), 25th (P = 0.004), 50th (P = 0.004), 75th (P = 0.006), and 90th percentiles (P = 0.013) and skewness (P = 0.021) than did the MMBC group. The 25th percentile of ADC values achieved the highest area under the curve (AUC) (0.792), with a cutoff value of 1.345 × 10-3 mm2 /s, in distinguishing PMBC and MMBC. The PMBC-A group showed significantly higher ADC values for the mean (P = 0.049), 25th (P = 0.015), and 50th (P = 0.026) percentiles and skewness (P = 0.004) than did the PMBC-B group. The 25th percentile of the ADC cutoff value (1.476 × 10-3 mm2 /s) demonstrated the best AUC (0.837) among the ADC values for distinguishing PMBC-A and PMBC-B. CONCLUSION: Whole-lesion ADC histogram analysis enables comprehensive evaluation of an MBC in its entirety and differentiating subtypes of MBC. Thus, it may be a helpful and supportive tool for conventional MRI. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:391-400.


Assuntos
Adenocarcinoma Mucinoso/diagnóstico por imagem , Neoplasias da Mama/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Adenocarcinoma Mucinoso/patologia , Mama/diagnóstico por imagem , Mama/patologia , Neoplasias da Mama/patologia , Diagnóstico Diferencial , Feminino , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade
9.
Eur Spine J ; 26(10): 2512-2519, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-26874953

RESUMO

PURPOSE: Using MR imaging, nerve root sedimentation sign (SedSign) was demonstrated to have a high sensitivity and specificity for diagnosis of symptomatic lumbar spinal stenosis (LSS) in selected patients. This study was to evaluate the diagnostic value of SedSign in differential diagnosis of LSS and non-specific low back pain (LBP) in consecutive patients. METHODS: A series of consecutive patients with lumbar spinal MRI examination for back/leg pain in orthopeadic clinic were included. These patients were followed up and divided into two groups, symptomatic LSS and non-specific LBP, according to symptoms and radiological findings. Using MR images, SedSign was assessed by two spine surgeons and one radiologist independently. Then sensitivity and specificity of SedSign was calculated. RESULT: A total of 320 patients (105 LSS and 215 non-specific LBP) were included. The SedSign had a sensitivity of 77.1 % and specificity of 47.0 % in the whole cohort. When these patients were stratified by dural sac cross-sectional areas (CSA), the SedSign had a sensitivity of 95.0 % and specificity of 4.7 % in patients with CSA ≤ 80 mm2 (severe radiologic stenosis), sensitivity of 74.2 % and specificity of 22.6 % in patients with CSA 80-100 mm2 (moderate radiologic stenosis), and sensitivity of 58.8 % and specificity of 61.0 % in patients with CSA 100-120 mm2 (mild radiologic stenosis). In selected cases composed by LSS patients with CSA ≤ 80 mm2 and non-specific LBP patients with CSA > 120 mm2, however, the SedSign had a sensitivity of 95.0 % and specificity of 80.0 %. CONCLUSION: The present data demonstrated that the SedSign was not able to discriminate symptomatic LSS from non-specific LBP after adjusting by dural sac CSA. The diagnostic value of the SedSign was still uncertain.


Assuntos
Vértebras Lombares/diagnóstico por imagem , Estenose Espinal/diagnóstico por imagem , Diagnóstico Diferencial , Humanos , Dor Lombar/diagnóstico por imagem , Imagem por Ressonância Magnética , Estudos Retrospectivos , Sensibilidade e Especificidade
10.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(11): 3176-81, 2015 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-26978931

RESUMO

Heavy metal mining activities have caused the complex influence on the ecological environment of the mining regions. For example, a large amount of acidic waste water containing heavy metal ions have be produced in the process of copper mining which can bring serious pollution to the ecological environment of the region. In the previous research work, bare soil is mainly taken as the research target when monitoring environmental pollution, and thus the effects of land surface vegetation have been ignored. It is well known that vegetation condition is one of the most important indictors to reflect the ecological change in a certain region and there is a significant linkage between the vegetation spectral characteristics and the heavy metal when the vegetation is effected by the heavy metal pollution. It means the vegetation is sensitive to heavy metal pollution by their physiological behaviors in response to the physiological ecology change of their growing environment. The conventional methods, which often rely on large amounts of field survey data and laboratorial chemical analysis, are time consuming and costing a lot of material resources. The spectrum analysis method using remote sensing technology can acquire the information of the heavy mental content in the vegetation without touching it. However, the retrieval of that information from the hyperspectral data is not an easy job due to the difficulty in figuring out the specific band, which is sensitive to the specific heavy metal, from a huge number of hyperspectral bands. Thus the selection of the sensitive band is the key of the spectrum analysis method. This paper proposed a statistical analysis method to find the feature band sensitive to heavy metal ion from the hyperspectral data and to then retrieve the metal content using the field survey data and the hyperspectral images from China Environment Satellite HJ-1. This method selected copper ion content in the leaves as the indicator of copper pollution level, using stepwise multiple linear regression and cross validation on the dataset which is consisting of 44 groups of copper ion content information in the polluted vegetation leaves from Dexing Copper Mine in Jiangxi Province to build up a statistical model by also incorporating the HJ-1 satellite images. This model was then used to estimate the copper content distribution over the whole research area at Dexing Copper Mine. The result has shown that there is strong statistical significance of the model which revealed the most sensitive waveband to copper ion is located at 516 nm. The distribution map illustrated that the copper ion content is generally in the range of 0-130 mg · kg⁻¹ in the vegetation covering area at Dexing Copper Mine and the most seriously polluted area is located at the South-east corner of Dexing City as well as the mining spots with a higher value between 80 and 100 mg · kg⁻¹. This result is consistent with the ground observation experiment data. The distribution map can certainly provide some important basic data on the copper pollution monitoring and treatment.

11.
Sensors (Basel) ; 14(5): 9271-89, 2014 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-24859029

RESUMO

The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8-10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy.


Assuntos
Agricultura/instrumentação , Monitoramento Ambiental/instrumentação , Florestas , Dispositivos Ópticos , Fotometria/instrumentação , Traqueófitas/crescimento & desenvolvimento , Transdutores , Desenho de Equipamento , Análise de Falha de Equipamento
12.
Acta Radiol ; 53(7): 812-9, 2012 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-22798291

RESUMO

BACKGROUND: Radiation-induced brain injury (RBI) is the most serious complication of primary and metastatic brain and neck malignant tumors following radiation therapy. However, at present, RBI is difficult to diagnose in the early period. Recently, studies have demonstrated that the early stage of RBI is characterized by an inflammatory reaction, and that intercellular adhesion molecule-1 (ICAM-1) is significantly up-regulated in the irradiated brain tissues. PURPOSE: To provide an early diagnosis of RBI using molecular magnetic resonance imaging (MRI) with microparticles of iron oxide (MPIO) targeted to ICAM-1 in the vascular endothelium of brains. MATERIAL AND METHODS: A monoclonal antibody against ICAM-1 was conjugated to MPIO to form the targeted MRI contrast agent ICAM-MPIO. The adhesion of ICAM-MPIO to endothelial cells was quantified by optical imaging and MRI. Sprague-Dawley rats were irradiated to establish an animal model of the early period of RBI. ICAM-MPIO and free-MPIO were injected via tail vein, respectively. T(2) signal intensity and T(2) values of the irradiated brains and normal brains were subsequently evaluated by MRI. RESULTS: In vitro, the adhesion of ICAM-MPIO to the activated endothelial cells was 5 ± 0.5-fold greater than to the non-stimulated cells, which could be detected by optical imaging and MRI (R(2) = 1.0, P < 0.01). In vivo, ICAM-MPIO caused a marked negative MRI contrast effect in irradiated brains. As compared with brains without irradiation, the specific contrast effect increased more than seven-fold after administration of ICAM-MPIO (F = 751.495, P < 0.05). CONCLUSION: MPIO coated with monoclonal antibody of ICAM-1 could be used for detecting the early period of RBI by optical imaging and MRI.


Assuntos
Lesões Encefálicas/patologia , Dextranos , Imagem por Ressonância Magnética/métodos , Nanopartículas de Magnetita , Lesões por Radiação/patologia , Análise de Variância , Animais , Anticorpos Monoclonais , Lesões Encefálicas/metabolismo , Linhagem Celular , Meios de Contraste , Modelos Animais de Doenças , Humanos , Molécula 1 de Adesão Intercelular/metabolismo , Tamanho da Partícula , Lesões por Radiação/metabolismo , Ratos , Ratos Sprague-Dawley , Regulação para Cima
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA