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1.
World J Pediatr ; 15(5): 506-510, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31520366

RESUMO

BACKGROUND: This study aimed to measure quality of life (QOL) in primary caregivers of young childrenwith Prader-Willi syndrome (PWS). METHODS: The caregivers of 32 children aged from 6.1 to 71.2 months completed the Chinese version of the World Health Organization Quality of Life-BREF (WHOQOL-BREF). We also evaluated the social adaption capacity of these children with Infants-Junior Middle School Students' Social-Life Abilities Scale. Correlation test was used to explore the related factors to caregivers' QOL. RESULTS: Caregivers of young children with PWS had significantly lower QOL. The correlation analyses revealed that caregivers' QOL was lower in children with young age, combined diseases or symptoms or poor social adaption, or caregivers having concerns about the child. CONCLUSIONS: Rearing a chilld with PWS may lead to decreased QOL. Psychological status of caregivers should be highlighted and social support should be given to families with PWS children.

2.
J Environ Radioact ; 208-209: 106036, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31493563

RESUMO

In order to develop an artificially constructed plant community plot for the enhanced phytoremediation of uranium contaminated soils, three uranium accumulators including Bamboo-willow (Salix sp.), Paspalum scrobiculatum linn and Macleaya cordata were used to construct four artificial plant community plots, and greenhouse experiments were conducted to investigate the bioaccumulation of uranium by the plants and the organic acid content, enzyme activity, and the change of microbial community structure in their rhizosphere soils. The transfer factor (TF) and the total bioaccumulation amount (TBA) of uranium were used to describe remediation efficiencies in this paper. It was found that their remediation efficiencies were in the order Bamboo-willow (Salix sp.)-Paspalum scrobiculatum linn-Macleaya cordata > Bamboo-willow (Salix sp.)-Macleaya cordata > Paspalum scrobiculatum linn-Macleaya cordata > Bamboo-willow (Salix sp.)-Paspalum scrobiculatum linn. The bioaccumulation amount of uranium by each plant in the Bamboo-willow (Salix sp.)-Paspalum scrobiculatum linn-Macleaya cordata community plot was significantly (P < 0.05) higher than that by its single population, the bioaccumulation amounts of uranium by Bamboo-willow (Salix sp.), Paspalum scrobiculatum linn and Macleaya cordata were 0.29, 0.32 and 2.19 mg/plant, respectively, and they were increased by 31.82%, 77.78% and 146.07%, respectively, and the transfer efficiencies by the plants were increased by 150%, 110% and 52.17%, respectively. The interaction between the plants' roots and the microorganisms in the rhizosphere soil of the Bamboo-willow (Salix sp.)-Paspalum scrobiculatum linn-Macleaya cordata community plot resulted in the high content of organic acids such as oxalic acid in the rhizosphere soil of the plant community plot, which was significantly (P < 0.05) higher than that of its single population. The chelation of the organic acids with uranium led to an increase in the proportion of exchangeable uranium in soil solution. In addition, Burkholderia, which is an iron-producing carrier bacterium and can increase the uptake and accumulation of uranium by plants, and Leptolyngbya, which is a plant growth promoting rhizobacteria and can increase the biomass of plants, emerged in the rhizosphere soil of the plant community plot. These may be the mechanisms by which the phytoremediation of the uranium contaminated soils was enhanced by the plant community plot.


Assuntos
Biodegradação Ambiental , Poluentes Radioativos do Solo/metabolismo , Urânio/metabolismo
3.
Phys Med Biol ; 64(14): 14NT01, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31167169

RESUMO

To improve the reconstruction condition and alleviate the noise amplification of GRAPPA reconstruction by aggregating the phase conjugated and nonlinear kernel mapped coils with the original physical coil. Nonlinear GRAPPA (NL-GRAPPA) is a kernel-based non-iterative approach which can reduce noise-induced error in GRAPPA reconstruction. And virtual conjugate coil (VCC) embeds the conjugate symmetric property of k-space into GRAPPA data synthesis to improve reconstruction condition. This work proposed NL-VCC-GRAPPA to jointly utilize the nonlinear mapped virtual coil and phase conjugated virtual coil to further reduce noise amplification in parallel imaging. In vivo static and dynamic 2D imaging accelerated by uniform undersampling schemes were performed to evaluate the proposed method in terms of visual image quality, root-mean-square-error (RMSE), and geometry factor (g-factor). The effects of acceleration factors, calibration data size and kernel shape on the proposed model were also separately analyzed and discussed. The proposed method illustrated improved visual image quality evidenced by reduced retrospective RMSE and prospective g-factor comparing with conventional GRAPPA and the recently proposed iterative SENSE-LORAKS reconstructions. Although a larger amount of calibration data and smaller kernel size were required to stabilize the calibration of fourfold extended kernel for the proposed method, it was non-iterative and relatively insensitive to parameter adjustment in the applications. The proposed NL-VCC-extension to conventional GRAPPA brings visible improvements for imaging scenarios accelerated by the widely available uniform undersampling schemes in a practically efficient manner without iteration.

4.
Dalton Trans ; 48(28): 10417-10421, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31241101

RESUMO

Dinuclear pincer-type cyclometalated Pd(ii) complexes with foldable diacetylide ligands show crystallographically determined intramolecular PdPd contacts of 3.203-3.380 Å. In deoxygenated fluid solutions, these Pd(ii) complexes are highly phosphorescent in the red region with emission quantum yields up to 48%, which has been ascribed to metal-metal-to-ligand charge-transfer (MMLCT) excited states in nature.

5.
Biomater Sci ; 7(7): 3007-3015, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31112151

RESUMO

Glioblastoma (GBM) is a deadly brain tumor with poor prognosis and high mortality in patients. Given the low efficacy and serious side effects of current GBM therapy compared to those of conventional surgery, chemotherapy and radiation therapy, the development of a novel method for GBM management is very urgent. Sonodynamic therapy (SDT) has gained considerable attention in GBM therapy due to the advantages of deep tissue penetration and high biosafety. However, the low reactive oxygen species (ROS) generation efficacy of SDT has generally limited further applications and clinical translation. In this work, we report the simultaneous application of focused ultrasound-induced moderate thermal treatment (42 °C) and SDT for synergistic enhancement against GBM. Manganese ion (Mn2+)-chelated human serum albumin (HSA)-chlorin e6 (Ce6) nanoassemblies (HCM NAs) as targeting nanosonosensitizers were prepared using an assembly strategy. Our studies indicated that the HCM NAs had excellent T1-weighted contrast performance (12.2 mM-1 s-1) compared to that of clinically used Magnevist (4.3 mM-1 s-1) and achieved highly selective in vitro cell recognition and in vivo tumor-targeting magnetic resonance (MR) and fluorescence (FL) imaging with a signal-to-background ratio of 13.5 at 24 h post injection. Upon imaging-guided focused ultrasound irradiation, the temperature and reactive oxygen species (ROS) content of the tumor region increased simultaneously over time, achieving synergistic effects. The brain tumors were completely suppressed in subcutaneous mouse models of glioma, and the antitumor effect was greatly improved in orthotopic mouse models of glioma. It suggest that the synergistic treatment with moderate temperature and SDT induced by imaging-guided focused ultrasound is a promising platform against GMB, holds great potential in clinical settings.

6.
Medicine (Baltimore) ; 98(15): e15013, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30985648

RESUMO

RATIONALE: Sitosterolemia is a rare autosomal recessive disorder of dyslipidemia due to mutations of genes ABCG5 and ABCG8, leading to highly elevated plasma levels of plant sterols and expanded body pools of cholesterol. PATIENT CONCERNS: We present a 9-year-old and a 7-year-old Chinese boy with hypercholesterolemia and xanthomas of sitosterolemia due to ABCG5 gene mutations. We also make a literature review of another 30 sitosterolemic children cases that have been reported with virulence ABCG5 gene mutations. DIAGNOSIS: We took peripheral blood samples from 2 patients and their parents to conduct genetic analysis by next-generation sequencing (NGS) technologies. INTERVENTIONS: The 2 patients received dietary modifications without pharmaceuticals treatment. OUTCOMES: A c.1166G>A (Arg389His) homozygosis mutation in exon 9 was observed in case 1, whereas a c.751C>T (Gln251*) homozygosis mutation in exon 6 was found in case 2. Literature review found another 30 pediatric cases with sitosterolemia due to ABCG5 gene mutation. The lipid profile was normalized and xanthomas got smaller with combined therapy of a combined low-cholesterol and low-phytosterols diet. LESSONS: These suggested that in patients (especially Asian patients) with multiple xanthomas, severe hypercholesterolemia, or elevated low-density lipoprotein-cholesterol, sitosterolemia should be considered in the differential diagnosis. Early diagnosis is important, and restriction of both cholesterol and phytosterols diet should suggested for these patients.


Assuntos
Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Hipercolesterolemia/genética , Enteropatias/genética , Erros Inatos do Metabolismo Lipídico/genética , Lipoproteínas/genética , Fitosteróis/efeitos adversos , Criança , Diagnóstico Diferencial , Humanos , Hipercolesterolemia/dietoterapia , Hipercolesterolemia/patologia , Hipercolesterolemia/fisiopatologia , Enteropatias/dietoterapia , Enteropatias/patologia , Enteropatias/fisiopatologia , Erros Inatos do Metabolismo Lipídico/dietoterapia , Erros Inatos do Metabolismo Lipídico/patologia , Erros Inatos do Metabolismo Lipídico/fisiopatologia , Masculino , Fenótipo , Fitosteróis/genética
7.
ACS Appl Mater Interfaces ; 11(18): 16285-16295, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-30986025

RESUMO

Engineering multiple theranostic modalities into a single nanoscale entity holds great potential to rejuvenate cancer treatments; however, enabling the sophisticated spatiotemporal control of each component for maximizing theranostic improvement and minimizing side effects concurrently remains a challenge. Herein, an intelligent detachable "nanorocket" is developed to sequentially manipulate and optimize multitheranostic processes for magnetic resonance-assisted ultrasound-drug combined therapy (MR-HIFU-Drug). The "nanorocket" is constructed by integrating multicomponent (MnCO3, doxorubicin, silica) on the pH-sensitive CaCO3 nanoparticles step by step via cation exchange and controlled heterogeneous nucleation, in which doxorubicin is encapsulated in both carbonates and silica component. The "nanorocket" can initiate sequential detachment in the acidic tumor microenvironment. Specifically, carbonates decompose instantly, releasing Mn2+ as the MR contrast agent and leaving hollow silica nanostructure behind as the HIFU synergistic agent. Consequently, burst release of drug is also triggered, further triggering the degradation of silica, which in turn regulates the slow release of drug from the silica matrix. Thus, efficient tumor inhibition is achieved by enhanced HIFU ablation and biphase release of doxorubicin with a stepwise clearance of Mn and Si. This work establishes a system for the systematic spatiotemporal dispatch of diverse theranostic components for the balance of efficacy and safety in cancer theranostics.


Assuntos
Doxorrubicina/administração & dosagem , Nanopartículas/administração & dosagem , Neoplasias/tratamento farmacológico , Nanomedicina Teranóstica/métodos , Animais , Carbonato de Cálcio/química , Linhagem Celular Tumoral , Doxorrubicina/química , Liberação Controlada de Fármacos , Humanos , Concentração de Íons de Hidrogênio , Imagem por Ressonância Magnética , Camundongos , Nanopartículas/química , Neoplasias/diagnóstico por imagem , Neoplasias/patologia , Ratos , Dióxido de Silício/química , Microambiente Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
8.
Magn Reson Med ; 82(1): 436-448, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30860290

RESUMO

PURPOSE: To develop a method based on fat-water transition region extraction (TREE) for robust fat-water separation and quantification in challenging scenarios, including low signal-to-noise ratio (SNR), fast changing B0 field, and disjointed anatomies. THEORY AND METHODS: In TREE method, the phasor solutions of each pixel were categorized into fat-dominant and water-dominant groups. The fat-water transition region was then extracted by detecting sudden changes in the phasor maps. The phasor solutions of the pixels in the transition region were solved by choosing the smoothest phasor combinations. For the remaining subregions, the phasor solution was then determined by all the surrounding transition region pixels. The proposed method was validated using various datasets, including some from the International Society for Magnetic Resonance in Medicine (ISMRM) 2012 Challenge. RESULTS: Quantitative score of proposed method (9936.8 of 10,000) is comparable to the winner (9951.9) of ISMRM 2012 Challenge. The total processing time was 179.3 s for 15 datasets. Sagittal spine data with ~400 mm field of view in head-foot direction were used to compare TREE with several representative region-growing methods. Results showed that the proposed method was robust under fast changing B0 field, disjointed anatomies and low SNR area. No apparent fat-water swap was observed in the low SNR (SNR ~ 10) dataset. Accurate proton density fat fraction results were also produced from the proposed method. CONCLUSION: A method based on fat-water transition region extraction was proposed for robust water-fat separation and fat fraction quantification. The method worked well in spatially disjointed objects, fast changing B0 field, and low SNR application.

9.
Environ Sci Pollut Res Int ; 26(9): 9203-9218, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30719673

RESUMO

In order to alleviate the shortage of land use accompanied with urbanization, over-track building complexes above metro depots are developed rapidly in China, resulting in the larger mechanical ventilation needs in the metro depot. Excessive noise exposure caused by the huge ventilation system will bring serious impacts on the health of workers in the metro depot. This research intends to evaluate the noise annoyance in the metro depot and the noise influences on adjacent residential buildings by the ventilation system. A questionnaire survey of 100 people working in a metro depot of Guangzhou Metro Line 6 was conducted, and field measurements inside the metro depot and inside adjacent residential buildings were carried out. The environmental noise level in the metro depot and the ventilation fan-induced noise level inside adjacent residential buildings exceed the corresponding criterion limit of China. Dose-response relationship modeled by logistic function was used to assess the noise annoyance, which is found underestimating the percentage of "Annoyed" (% A) and percentage of "Little Annoyed" (% LA) of staffs in the metro depot, especially for the % LA. This may be attributed to the reducing reliability of dose-effect curves as the Ldn is higher than 65 dB(A). In order to alleviate the noise impact, noise-controlling measures need to be took. However, traditional noise-controlling measures cannot solve low-frequency noise disturbance.


Assuntos
Exposição Ambiental/análise , Ruído dos Transportes , Ferrovias , China , Exposição Ambiental/estatística & dados numéricos , Habitação , Humanos , Reprodutibilidade dos Testes , Inquéritos e Questionários , Urbanização , Ventilação
10.
Environ Sci Pollut Res Int ; 26(9): 8502-8515, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30806927

RESUMO

Noise pollution is a major factor of environmental complaints in many cities, which has significant impacts on human health. As a dominating source of environmental noise, the impact of road traffic noise is increasing. Residents living in high-rise buildings along the main road are severely affected by traffic noise. In order to assess the noise level of urban area along the main road in Guangzhou, three buildings were selected to conduct traffic noise measurements, and the questionnaire about traffic noise impact on human being was completed. Through the questionnaire, around 70% of participants consider the traffic noise has negative effect, and about 60% of participants consider the noise has moderate or much higher impact on physical comfort. Around 65% of participants consider the noise had moderately or much higher impact on their psychological comfort. By analyzing the measured data, all of the measured noise levels in three buildings exceed the recommended limit of 55 dB (A) in the daytime and 45 dB (A) in the night for residence, and the exceeded value can be up to 16 dB (A). By comparing the fitting curve of noise level transfer function on each floor relative to the reference floor, the quadratic polynomial was selected to plot the transfer function rather than cubic polynomial.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Ruído dos Transportes , Algoritmos , Cidades , Feminino , Habitação , Humanos , Masculino , Inquéritos e Questionários , Adulto Jovem
11.
Small ; 15(32): e1805381, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30773813

RESUMO

Sodium-ion batteries (SIBs) are attracting increasing attention and considered to be a low-cost complement or an alternative to lithium-ion batteries (LIBs), especially for large-scale energy storage. Their application, however, is limited because of the lack of suitable host materials to reversibly intercalate Na+ ions. Layered transition metal oxides (Nax MO2 , M = Fe, Mn, Ni, Co, Cr, Ti, V, and their combinations) appear to be promising cathode candidates for SIBs due to their simple structure, ease of synthesis, high operating potential, and feasibility for commercial production. In the present work, the structural evolution, electrochemical performance, and recent progress of Nax MO2 as cathode materials for SIBs are reviewed and summarized. Moreover, the existing drawbacks are discussed and several strategies are proposed to help alleviate these issues. In addition, the exploration of full cells based on Nax MO2 cathodes and future perspectives are discussed to provide guidance for the future commercialization of such systems.

12.
Indian J Pediatr ; 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30406597
13.
Rev Sci Instrum ; 89(9): 094901, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30278729

RESUMO

There is much debate about whether the junction temperature or phosphor temperature is higher in white light-emitting diodes (LEDs). The main reason is that the junction and phosphor temperatures cannot be measured directly using traditional temperature measurement tools. In this study, a magnetic nanoparticle thermometer, a nondestructive and precise temperature measurement tool, is introduced and described in detail. The model, measurement principle, and experimental setup are described. The temperature of the phosphor layer and the top surface of the P-N junction in white LEDs was measured directly using the magnetic nanoparticle thermometer, and the results show that the phosphor layer temperature was higher than the chip top surface temperature at different input voltages, providing a reference for relative researchers.

14.
Magn Reson Med ; 2018 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-30230595

RESUMO

PURPOSE: The aim of this study was to propose dual-step iterative temperature estimation (DITE) of a fat-referenced proton resonance frequency shift (PRFS) method to improve both the accuracy and precision of temperature estimations in fat-containing tissues. METHODS: A fat-water signal model with multiple fat peaks was used to simultaneously estimate the temperature, fat/water intensity and T2* , and field offset. In DITE, model fitting was implemented with alternating 2-step minimizations. The estimated temperature map was smoothed between the 2-step minimizations, which is considered to be the most important step for improving the temperature precision. The performance of DITE was evaluated with a Monte Carlo simulation, fat/water phantoms, and ex vivo brown adipose tissue experiments and then compared with the performance of previous fat-referenced proton resonance frequency shift methods. RESULTS: In fat/water phantom experiment with a smooth temperature profile, the temperatures estimated by DITE are consistent with the thermometer results and present a better accuracy and precision than those of previous fat-referenced proton resonance frequency shift methods. In the brown adipose tissue heating experiment, the average mean error, SD, and RMS error were -0.08ºC, 0.46ºC, and 0.56ºC, respectively, over all of the measurements within the region of interest. CONCLUSION: Our proposed DITE method improves both the accuracy and precision of temperature measurements in tissues with fat fractions between 20% and 80% under smooth distribution of the temperature profile and represents a simple fat-referenced thermometry method.

15.
Chem Asian J ; 13(21): 3092-3105, 2018 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-30098122

RESUMO

Lyotropic chromonic (LC) mesophases have received a large amount of attention, owing to the semi-stable nature of the chromonics. In these systems, the balance between the ordering forces and the thermal motion is delicate. As such, temperature changes, concentration variations, alterations to the electric and magnetic fields, and the addition of additives to the chromonic systems can be sensitively monitored. Herein, we review the general characterization methods for lyotropic chromonic mesophases, including polarized optical microscopy (POM), multinuclear NMR spectroscopy, X-ray diffractometry, cryo-TEM, and rheology. In recent years, lyotropic chromonic mesophases that are derived from metal-organic complexes have become established and offer the possibility of introducing the rich functionalities of the metal complexes into these systems. The chromonic properties, aggregation behaviors, and influence factors on such systems are reviewed case-by-case. Finally, preliminary attempts to utilize these systems are reviewed, which have demonstrated their potential application in optical devices, biosensing, luminescent materials, etc.

16.
MAGMA ; 31(6): 771-779, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29948236

RESUMO

PURPOSE: Real-time monitoring is important for the safety and effectiveness of high-intensity focused ultrasound (HIFU) therapy. Magnetic resonance imaging is the preferred imaging modality for HIFU monitoring, with its unique capability of temperature imaging. For real-time temperature imaging, higher temporal resolution and larger spatial coverage are needed. In this study, a sequence based on the echo-shifted RF-spoiled gradient echo (GRE) with simultaneous multi-slice (SMS) imaging was designed for fast temperature imaging. METHODS: A phantom experiment was conducted to evaluate the accuracy of the echo-shifted sequence using a fluorescent fiber thermometer as reference. The temperature uncertainty of the echo-shifted sequence was compared with the traditional GRE sequence at room temperature through the ex vivo porcine muscle. Finally, the ex vivo porcine liver tissue experiment using HIFU heating was performed to demonstrate that the spatial coverage was increased without decreasing temporal resolution. RESULTS: The echo-shifted sequence had a better temperature uncertainty performance compared with the traditional GRE sequence with the same temporal resolution. The ex vivo heating experiment confirmed that by combining the SMS technique and echo-shifted sequence, the spatial coverage was increased without decreasing the temporal resolution while maintaining high temperature measurement precision. CONCLUSION: The proposed technique was validated as an effective real-time method for monitoring HIFU therapy.

17.
Lipids Health Dis ; 17(1): 131, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29859112

RESUMO

BACKGROUND: Achilles tendons are the most common sites of tendon xanthomas that are commonly caused by disturbance of lipid metabolism. Achilles tendon thickening is the early characteristic of Achilles tendon xanthomas. The relationship between Achilles tendon thickness (ATT) and LDL-C levels, and risk factors of ATT in patients with hypercholesterolemia, have thus far been poorly documented. METHODS: A total of 205 individuals, aged 18-75 years, were enrolled from March 2014 to March 2015. According to the LDL-C levels and the "Chinese Guidelines on Prevention and Treatment of Dyslipidemia in Adults", all subjects were divided into 3 groups: normal group (LDL-C < 3.37 mmol/L, n = 51); borderline LDL-C group (3.37 mmol/L ≤ LDL-C ≤ 4.12 mmol/L, n = 50); and hypercholesterolemia group (LDL ≥ 4.14 mmol/L, n = 104). ATT was measured using a standardized digital radiography method and the results were compared among the 3 groups. The correlation between ATT and serum LDL-C levels was analyzed by Pearson's correlation, and the risk factors of ATT were determined by the logistic regression model. RESULTS: ATT in borderline LDL-C group was 8.24 ± 1.73 mm, markedly higher than 6.05 ± 0.28 mm of normal group (P < 0.05). ATT in hypercholesterolemia group was 9.42 ± 3.63 mm which was significantly higher than that of normal group (P < 0.005) and that of borderline LDL-C group (P < 0.05). There was a positive correlation between the serum LDL-C levels and ATT (r = 0.346, P < 0.001). The serum LDL-C level was a risk factor (OR = 1.871, 95% CI: 1.067-3.280) while the levels of HDL-C (OR = 0.099, 95% CI: 0.017-0.573) and Apo AI (OR = 0.035, 95% CI: 0.003-0.412) were protective factors of ATT. CONCLUSIONS: ATT might serve as a valuable auxiliary diagnostic index for hypercholesterolemia and used for the assessment and management of cardiovascular disease.


Assuntos
Tendão do Calcâneo/patologia , LDL-Colesterol/sangue , Hipercolesterolemia/patologia , Xantomatose/epidemiologia , Adolescente , Adulto , Idoso , Feminino , Humanos , Hipercolesterolemia/sangue , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Xantomatose/sangue , Adulto Jovem
18.
Sci Total Environ ; 637-638: 431-442, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29754078

RESUMO

The relative importance of contributions of gasoline vehicles (GVs) and diesel vehicles (DVs), heavy-duty diesel vehicles (HDDVs) and non-HDDVs to on-road vehicle emissions remains unclear. Vehicle emission factors (EFs), including fine particulate matter (PM2.5), NO-NO2-NOx, and carbon monoxide (CO), were measured (August 4-18, 2017) in an urban tunnel in Tianjin, northern China. The average EFs (mg km-1 veh-1) of the fleet were as follows: 9.21 (95% confidence interval: 1.60, 23.07) for PM2.5, 62.08 (21.21, 138.25) for NO, 20.42 (0.79, 45.48) for NO2, 83.72 (26.29, 162.87) for NOx, and 284.54 (18.22, 564.67) for CO. The fleet-average EFs exhibited diurnal variations, due to diurnal variations in the proportion of HDDVs in the fleet, though the hourly proportion of HDDVs never exceeded 10% during the study period. The reconstructed average EFs for on-road vehicle emissions of PM2.5, NO, NO2, and NOx, and CO were approximately 2.2, 1.7, 1.5, 2.0, and 1.6 times as much as those in the tunnel, respectively, due to the higher HDDV fractions in the whole city than those in the tunnel. The EFs of PM2.5, NO, NO2, and NOx, and CO from each HDDV were approximately 75, 81, 24, 65, and 33 times of those from each non-HDDV, respectively. HDDVs were responsible for approximately 81.92%, 83.02%, 59.79%, 79.79%, and 66.77% of the total PM2.5, NO, NO2, and NOx, and CO emissions from on-road vehicles in Tianjin, respectively. DVs, especially HDDVs, are major sources of on-road PM2.5, NO-NO2-NOx, and CO emissions in northern China. The contribution of HDDVs to fleet emissions calculated by the EFs from Chinese 'on-road vehicle emission inventory guidebook' were underestimated, as compared to our results. The EFs from on-road vehicles should be updated due to the rapid progression of vehicle technology combined with emission standards in China. The management and control of HDDV emissions have become urgent to reduction of on-road vehicle emissions.

19.
Chem Commun (Camb) ; 54(42): 5319-5322, 2018 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-29736527

RESUMO

Extended intercationic PdPd contacts of 3.30 Å in the crystal structure and distinct MMLCT transitions absorbing at 528 nm and emitting beyond 600 nm in solutions have been revealed with cyclometalated Pd(ii) N-heterocyclic allenylidene complexes. The Pd(ii)-based MMLCT excited states are responsive to concentrations, temperatures, mechanical force and organic vapors.

20.
J Magn Reson ; 292: 25-35, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29758451

RESUMO

PURPOSE: The purpose of this study is to evaluate the effect of diffusion on SSFP (Steady-state Free Precession) signals in triple-echo steady state (TESS) sequence and ultimately on the accuracy of T2 relaxometry. METHODS: The extended phase graph (EPG) algorithm was used to study the effect of diffusion on SSFP signals and T2 relaxometry. The simulation results were verified by a commercial phantom and in vivo studies. Based on the simulation results, a correction scheme was proposed to correct the estimated T2 values. RESULTS: T2 underestimation in TESS was evident in case of small flip angle and large unbalanced gradient moment on objects with large T2 and D values. The T2 underestimation mainly originated from the diffusion sensitivity of SSFP-echo. It was also observed that SSFP-FID (Free Induction Decay) signals increased with increasing diffusion weighting under some specific conditions. The proposed correction scheme corrected the T2 underestimation, which verified that the underestimation was due to the neglect of diffusion effect. For clinical practice of TESS in tissues with short T2 such as cartilage and muscle, the diffusion effect of TESS is negligible. CONCLUSION: The effect of diffusion cannot be neglected during TESS T2 quantification as it is the main source of T2 underestimation when small flip angle and large unbalanced gradient moment is used, especially for objects with large T2 and D values.

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