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1.
Artigo em Inglês | MEDLINE | ID: mdl-36520283

RESUMO

Harmful algal blooms is a widespread problem in aquatic ecosystems, in particular dinoflagellates that produce PSTs which are harmful to animal and human health. To explore the contamination status of PSTs in shellfish in the Southeastern China, a total of 2355 shellfish samples were analyzed by ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to study the toxin profiles of the 10 PSTs collected from the southeast coast of China from 2017 to 2021. From 2355 shellfish samples, 257 were detected (10.91%), with the highest value in samples of Perna viridis. Among the six source areas in China, the samples from Fujian recorded the highest detected rate (15.28%). PSTs were found in Fuzhou, Ningde, Quanzhou, Putian, Zhangzhou, and Xiamen, with Quanzhou and Fuzhou having the highest and lowest detection rates of 15.28% and 4.23%, respectively. Saxitoxin (STX), neosaxitoxin (neoSTX), gonyautoxin (GTX1, GTX2, GTX3, GTX4), N-sulfocarbamoyl toxin (GTX5), and decarbamoyl toxin (dcSTX, dcGTX2, dcGTX3) were detected, and GTX5 and dcGTX2 were dominant. In addition, the samples containing PSTs were mostly concentrated in May to August. The study confirms the risks of PSTs to shellfish consumers in the region. It will offer a great foundation for future monitoring of marine toxins and protecting the health of seafood consumers in China. This is the first detailed evaluation of PSTs occurrences and their profiles in shellfish from the Southeastern China over a period of multiple years. HIGHLIGHTS: 2355 mussels from China were analyzed by UPLC-MS/MS for PSTs in 2017-2021. The predominant PSTs were GTX5, neoSTX and dcGTX2. Arca granosa and Crassostyea gigas exhibited higher levels than other shellfish. Shellfish containing PSTs were mostly concentrated in May to August. Maximum detected level in shellfish was 2137.10 ug STXeq/kg.

2.
Micromachines (Basel) ; 13(5)2022 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-35630275

RESUMO

The Negative Bias Temperature Instability (NBTI) effect of partially depleted silicon-on-insulator (PDSOI) PMOSFET based on 130 nm is investigated. First, the effect of NBTI on the IV characteristics and parameter degradation of T-Gate PDSOI PMOSFET was investigated by accelerated stress tests. The results show that NBTI leads to a threshold voltage negative shift, saturate drain current reduction and transconductance degradation of the PMOSFET. Next, the relationship between the threshold voltage shift and stress time, gate bias and temperature, and the channel length is investigated, and the NBTI lifetime prediction model is established. The results show that the NBTI lifetime of a 130 nm T-Gate PDSOI PMOSFET is approximately 18.7 years under the stress of VG = -1.2 V and T = 125 °C. Finally, the effect of the floating-body effect on NBTI of PDSOI PMOSFET is investigated. It is found that the NBTI degradation of T-Gate SOI devices is greater than that of the floating-body SOI devices, which indicates that the floating-body effect suppresses the NBTI degradation of SOI devices.

3.
Psychiatry Res ; 312: 114560, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35500333

RESUMO

To assess the effect of aerobic exercise (AZ) on global cognition and different cognition domains in patients with schizophrenia (SZ) in daily care. Selection of the literature was done through the Pubmed, Web of Science, Embase and Cochrane Library databases. Standardized mean difference (SMD) and 95% confidence intervals (CIs) were used to assess the effect of AZ on cognition of SZ patients. All assessment indicators were subjected to sensitivity analysis to test the stability of the result. Subgroup analysis was conducted on study type, follow-up time, supervisor and control method. Totally, 23 articles enrolling 1014 participants were included. The global cognition of SZ patients was improved after 6 months of follow-up. AE guided by an occupational therapist improved the global cognition of SZ patients. AE was associated with improved verbal learning and memory, reasoning and problem solving (SMD: 0.375, 95%CI: 0.009 to 0.741, P = 0.045). However, effects on speed of processing, attention/vigilance, work memory, visual learning and memory, social cognition were not significant. The effect of AE training on global cognition may be maintained over the long-term, and be domain specific. Patients with SZ can do AE guided by professional occupational therapist in their daily lives settings.


Assuntos
Transtornos Cognitivos , Esquizofrenia , Atenção , Cognição , Transtornos Cognitivos/complicações , Exercício Físico , Humanos , Esquizofrenia/complicações , Esquizofrenia/terapia
4.
Medicine (Baltimore) ; 100(1): e23876, 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33429747

RESUMO

OBJECTIVES: To assess the effect of aerobic exercise (AE) on cognition function in people with schizophrenia (SZ) during daily nursing. METHODS: The literature search will be conducted via PubMed, Embase, Cochrane Library, and Web of Science. Weighted mean difference (WMD) or standardized mean difference (SMD) and 95% confidence intervals (CIs) will be adopted to calculate the association between AE and cognitive function in patients with SZ. Publication bias will be performed by Begg test. When there is publication bias, "cut-and-fill method" will be adopted to adjust publication bias. Sensitivity analysis will be used to test the stability of the result. When the heterogeneity is large (I2 ≥ 50%), meta regression will be used to explore the source of inter-study heterogeneity. When the heterogeneity is large (I2 ≥ 50%) and the results are statistically significant (P < .05), age, sex, duration of disease, duration of intervention, amount of exercise per week, improvement of cardiopulmonary health, and other factors will be sub-analyzed. CONCLUSION: This meta-analysis will evaluate the impact of aerobic exercise on cognitive function in patients with SZ during daily nursing on the basis of existing evidence. OSF REGISTRATION NUMBER: 10.17605/OSF.IO/C8ABX.


Assuntos
Protocolos Clínicos , Cognição/fisiologia , Exercício Físico/fisiologia , Esquizofrenia/enfermagem , Correlação de Dados , Exercício Físico/psicologia , Humanos , Metanálise como Assunto , Cuidados de Enfermagem/métodos , Cuidados de Enfermagem/normas , Revisões Sistemáticas como Assunto
5.
Adv Mater ; 32(29): e2000953, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32519397

RESUMO

Advanced microscopy and/or spectroscopy tools play indispensable roles in nanoscience and nanotechnology research, as they provide rich information about material processes and properties. However, the interpretation of imaging data heavily relies on the "intuition" of experienced researchers. As a result, many of the deep graphical features obtained through these tools are often unused because of difficulties in processing the data and finding the correlations. Such challenges can be well addressed by deep learning. In this work, the optical characterization of 2D materials is used as a case study, and a neural-network-based algorithm is demonstrated for the material and thickness identification of 2D materials with high prediction accuracy and real-time processing capability. Further analysis shows that the trained network can extract deep graphical features such as contrast, color, edges, shapes, flake sizes, and their distributions, based on which an ensemble approach is developed to predict the most relevant physical properties of 2D materials. Finally, a transfer learning technique is applied to adapt the pretrained network to other optical identification applications. This artificial-intelligence-based material characterization approach is a powerful tool that would speed up the preparation, initial characterization of 2D materials and other nanomaterials, and potentially accelerate new material discoveries.

6.
Soc Cogn Affect Neurosci ; 14(8): 911-918, 2019 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-31506681

RESUMO

Inspired by the roles of serotonin in an emotional aversion to harmful actions, we examined to what extent serotonin transporter gene (5-HTT)-linked polymorphic region (5-HTTLPR), a proxy for measuring serotonin function, underpinned the individual differences in moral judgment through cross-sectional analysis and two-wave comparison. The cross-sectional analysis with a larger cohort (N = 1197) showed that the SS carriers of the 5-HTTLPR polymorphism, corresponding to the low ratio of serotonin recycling from the synaptic cleft, rated impersonal harmful actions (e.g. flipping a switch to divert a train to hit one person instead of five people) as more permissible as compared with the L-allele carriers. The two-wave comparison with a subsample from the larger cohort (N = 563) indicated that the association between 5-HTTLPR polymorphism and moral permissibility of impersonal harmful actions was stable from wave 1 to wave 2. Thus, these findings highlight the importance of the 5-HTTLPR polymorphism to harmful moral behaviors.


Assuntos
Emoções , Princípios Morais , Polimorfismo Genético , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Adulto , Alelos , Estudos Transversais , Feminino , Genótipo , Humanos , Julgamento , Masculino , Serotonina
7.
Phys Rev Lett ; 123(9): 097601, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31524450

RESUMO

Complex systems, which consist of a large number of interacting constituents, often exhibit universal behavior near a phase transition. A slowdown of certain dynamical observables is one such recurring feature found in a vast array of contexts. This phenomenon, known as critical slowing-down, is well studied mostly in thermodynamic phase transitions. However, it is less understood in highly nonequilibrium settings, where the time it takes to traverse the phase boundary becomes comparable to the timescale of dynamical fluctuations. Using transient optical spectroscopy and femtosecond electron diffraction, we studied a photoinduced transition of a model charge-density-wave (CDW) compound LaTe_{3}. We observed that it takes the longest time to suppress the order parameter at the threshold photoexcitation density, where the CDW transiently vanishes. This finding can be captured by generalizing the time-dependent Landau theory to a system far from equilibrium. The experimental observation and theoretical understanding of dynamical slowing-down may offer insight into other general principles behind nonequilibrium phase transitions in many-body systems.

8.
Artigo em Inglês | MEDLINE | ID: mdl-30707988

RESUMO

BACKGROUNDS: Alexithymia refers to the difficulties in identifying and describing one's own emotions, lacking of imagination, and an externally oriented thinking style. Studies up to date have examined the associations of 5-HTTLPR and COMT Val158Met polymorphisms with alexithymia. However, the previous findings were mixed. METHODS: We replicated the associations by scoring on alexithymia with the 20-item Toronto Alexithymia Scale and genotyping the polymorphisms of 5-HTTLPR and COMT Val158Met in a large population of college students (N = 1698). Moreover, we also meta-analyzed the associations with five samples (N = 7517) for the 5-HTTLPR and with five samples (N = 2186) for the COMT Val158Met. RESULTS: Neither the replicated study nor the meta-analyses indicated the 5-HTTLPR and COMT Val158Met were associated with alexithymia. CONCLUSIONS: The findings suggest that the 5-HTTLPR and COMT Val158Met polymorphisms are not associated with alexithymia. However, genetic-environmental studies with different ethnicity and psychopathology should be carried in future.


Assuntos
Sintomas Afetivos/genética , Catecol O-Metiltransferase/genética , Predisposição Genética para Doença/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Feminino , Genótipo , Humanos , Masculino , Polimorfismo de Nucleotídeo Único/genética , Adulto Jovem
9.
Psychoneuroendocrinology ; 103: 8-13, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30605805

RESUMO

Polymorphisms in the oxytocin receptor (OXTR) gene have been shown to be related to individual differences in social skills that are important for building and maintaining social relationships, such as the capability to efficiently process social information and regulate emotions. However, what remains unclear is the potential roles of OXTR polymorphisms in interpersonal adaptability, namely the ability to cope with the situational demands of interpersonal interactions. In this study, we examined the roles of OXTR rs53576 polymorphism in interpersonal adaptability, empathic perception, and dispositional forgiveness in a cohort of 573 college freshmen. The results indicated that the scores on interpersonal adaptability and dispositional forgiveness, apart from empathic perception, increased as functions of the number of G alleles of OXTR rs53576. Moreover, dispositional forgiveness, but not empathic perception, mediated the association between OXTR rs53576 and interpersonal adaptability. The findings highlight the influences of the OXTR gene on adaptive interpersonal interactions, especially when individuals face changing social situations.


Assuntos
Perdão/genética , Relações Interpessoais , Receptores de Ocitocina/genética , Adolescente , China , Emoções/fisiologia , Empatia/genética , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Ocitocina/genética , Ocitocina/metabolismo , Personalidade/genética , Polimorfismo de Nucleotídeo Único , Receptores de Ocitocina/metabolismo , Ajustamento Social , Habilidades Sociais , Adulto Jovem
10.
Nano Lett ; 18(8): 5205-5210, 2018 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-30005161

RESUMO

Imaging materials and inner structures with resolution below the diffraction limit has become of fundamental importance in recent years for a wide variety of applications. We report subdiffractive internal structure diagnosis of hexagonal boron nitride by exciting and imaging hyperbolic phonon polaritons. On the basis of their unique propagation properties, we are able to accurately locate defects in the crystal interior with nanometer resolution. The precise location, size, and geometry of the concealed defects are reconstructed by analyzing the polariton wavelength, reflection coefficient, and their dispersion. We have also studied the evolution of polariton reflection, transmission, and scattering as a function of defect size and photon frequency. The nondestructive high-precision polaritonic structure diagnosis technique introduced here can be also applied to other hyperbolic or waveguide systems and may be deployed in the next-generation biomedical imaging, sensing, and fine structure analysis.


Assuntos
Compostos de Boro/química , Nanoestruturas/química , Fônons , Simulação por Computador , Estrutura Molecular , Tamanho da Partícula
11.
Adv Mater ; 30(16): e1706358, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29532960

RESUMO

Hexagonal boron nitride (hBN) is a natural hyperbolic material that supports both volume-confined hyperbolic polaritons and sidewall-confined hyperbolic surface polaritons (HSPs). In this work, efficient excitation, control, and steering of HSPs are demonstrated in hBN through engineering the geometry and orientation of hBN sidewalls. By combining infrared nanoimaging and numerical simulations, the reflection, transmission, and scattering of HSPs are investigated at the hBN corners with various apex angles. It is also shown that the sidewall-confined nature of HSPs enables a high degree of control over their propagation by designing the geometry of hBN nanostructures.

12.
Conscious Cogn ; 55: 205-213, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28888137

RESUMO

Testosterone and estrogen are involved in self-related behavioral dispositions and experiences of subjective well-being. In this study, we investigated to what extent the aromatase (CYP19A1) gene, which encodes an enzyme in converting testosterone into estrogen, contributes to subjective well-being and in another self-related disposition: independent and interdependent self-construal. In study 1, a meta-analysis showed that the GG genotype of CYP19A1 (a G/A substitution at Val80, rs700518) was associated with higher testosterone and lower estradiol. In study 2, an empirical study of individuals with the GG (n=115), AG (n=286) and AA (n=193) genotypes indicated that individuals with the GG genotype exhibited higher independent self-construal and higher subjective well-being. The association between the GG genotype of CYP19A1 Val80 and subjective well-being was mediated by the independent self-construal. Our findings reinforce the idea that personality traits such as independent self-construal explain the link between genetic variant and subjective well-being.


Assuntos
Aromatase/fisiologia , Estradiol/sangue , Satisfação Pessoal , Personalidade/fisiologia , Autoimagem , Testosterona/sangue , Adulto , Aromatase/genética , Feminino , Genótipo , Humanos , Masculino , Adulto Jovem
13.
Nano Lett ; 17(9): 5285-5290, 2017 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-28805397

RESUMO

We investigated phonon-polaritons in hexagonal boron nitride-a naturally hyperbolic van der Waals material-by means of the scattering-type scanning near-field optical microscopy. Real-space nanoimages we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied. Our work may inform future development of polaritonic nanodevices as well as fundamental studies of collective modes in van der Waals materials.

14.
PLoS One ; 11(9): e0162028, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27658309

RESUMO

Brain aging is a complex and heterogeneous process characterized by the selective loss and preservation of brain functions. This study examines the normal aging effects on the cerebral cortex by characterizing changes in functional connectivity using resting-state fMRI data. Previous resting-state fMRI studies on normal aging have examined specific networks of the brain, whereas few studies have examined cortical-cortical connectivities across the entire brain. To characterize the effects of normal aging on the cerebral cortex, we proposed the Pearson functional product-moment correlation coefficient for measuring functional connectivity, which has advantages over the traditional correlation coefficient. The distinct patterns of changes in functional connectivity within and among the four cerebral lobes clarified the effects of normal aging on cortical function. Besides, the advantages of the proposed approach over other methods considered were demonstrated through simulation comparisons. The results showed heterogeneous changes in functional connectivity in normal aging. Specifically, the elderly group exhibited enhanced inter-lobe connectivity between the frontal lobe and the other lobes. Inter-lobe connectivity decreased between the temporal and parietal lobes. The results support the frontal aging hypothesis proposed in behavioral and structural MRI studies. In conclusion, functional correlation analysis enables differentiation of changes in functional connectivities and characterizes the heterogeneous aging effects in different cortical regions.

15.
Nano Lett ; 15(3): 1898-903, 2015 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-25654184

RESUMO

We report high quality graphene and WSe2 devices encapsulated between two hexagonal boron nitride (hBN) flakes using a pick-up method with etched hBN flakes. Picking up prepatterned hBN flakes to be used as a gate dielectric or mask for other 2D materials opens new possibilities for the design and fabrication of 2D heterostructures. In this Letter, we demonstrate this technique in two ways: first, a dual-gated graphene device that is encapsulated between an hBN substrate and prepatterned hBN strips. The conductance of the graphene device shows pronounced Fabry-Pérot oscillations as a function of carrier density, which implies strong quantum confinement and ballistic transport in the locally gated region. Second, we describe a WSe2 device encapsulated in hBN with the top hBN patterned as a mask for the channel of a Hall bar. Ionic liquid selectively tunes the carrier density of the contact region of the device, while the hBN mask allows independent tunability of the contact region for low contact resistance. Hall mobility larger than 600 cm(2)/(V·s) for few-layer p-type WSe2 at 220 K is measured, the highest mobility of a thin WSe2 device reported to date. The observations of ballistic transport in graphene and high mobility in WSe2 confirm pick-up of prepatterned hBN as a versatile technique to fabricate ultraclean devices with high quality contact.

16.
PLoS One ; 9(10): e103079, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25313674

RESUMO

BACKGROUND: MicroRNAs (miRNAs) are small ribonucleotides regulating gene expression. MicroRNAs are present in the blood in a remarkably stable form and have emerged as potential diagnostic markers in patients with cardiovascular disease. Our study aimed to assess circulating miR-133a levels in MHD patients and the relation of miR-133a to cardiac hypertrophy. METHODS: We profiled miRNAs using RNA isolated from the plasma of participants. The results were validated in 64 MHD patients and 18 healthy controls. RESULTS: Levels of plasma miR-133a decreased in MHD patients with LVH compared with those in healthy controls. Plasma miR-133a concentrations were negatively correlated with LVMI and IVS. After single hemodialytic treatment, plasma miR-133a levels remained unchanged. Cardiac Troponin I and T were not associated with LVMI and IVS. CONCLUSIONS: Our observations supplied the possibility that circulating miR-133a could be a surrogate biomarker of cardiac hypertrophy in MHD patients.


Assuntos
Cardiomegalia/diagnóstico , Falência Renal Crônica/diagnóstico , MicroRNAs/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Cardiomegalia/complicações , Cardiomegalia/genética , Feminino , Ventrículos do Coração/diagnóstico por imagem , Humanos , Falência Renal Crônica/complicações , Modelos Logísticos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Diálise Renal , Troponina I/metabolismo , Troponina T/metabolismo , Ultrassonografia
17.
Biomed Pharmacother ; 68(6): 699-707, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25070394

RESUMO

Breast cancer has been considered to be a multifactorial disease with a wide array of well-characterized gene mutations and chromosomal abnormalities. However, it is becoming evident that the onset or development of breast cancer also depends on epigenetic factors, although the mechanisms have not been fully elucidated. We performed a genome-wide analysis of DNA methylation of breast carcinomatous tissues and paired normal tissues to examine the differences in methylation between them. Methylation-specific polymerase chain reaction (MSP) was used to validate the hypermethylated genes screened out by DNA methylation microarray. We found that hypomethylation and hypermethylation occurred in 2753 and 1795 genes, respectively, in breast carcinomatous tissues. Meanwhile, gene ontology analysis and ingenuity pathway analysis revealed the function and pathway of several genes whose methylation status was altered in breast carcinomatous tissues. In addition, we investigated the promoter methylation status of four genes in breast carcinomatous tissue and paired normal tissues (n=30) by MSP. Promoter hypermethylation of CRABP1, HOXB13, IFNGR2, and PIK3C3 was found in 37% (11/30), 23% (7/30), 17% (5/30), and 2% (2/30) of the carcinomas, respectively. Mutation of these four important genes was critical to many types of cancer. Our results suggest that DNA methylation mechanisms may be involved in regulating the occurrence and development of breast cancer.


Assuntos
Neoplasias da Mama/metabolismo , Mama/metabolismo , Metilação de DNA/fisiologia , Redes Reguladoras de Genes/fisiologia , Neoplasias da Mama/genética , Feminino , Humanos , Pessoa de Meia-Idade
18.
Nat Nanotechnol ; 9(4): 262-7, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24608231

RESUMO

The p-n junction is the functional element of many electronic and optoelectronic devices, including diodes, bipolar transistors, photodetectors, light-emitting diodes and solar cells. In conventional p-n junctions, the adjacent p- and n-type regions of a semiconductor are formed by chemical doping. Ambipolar semiconductors, such as carbon nanotubes, nanowires and organic molecules, allow for p-n junctions to be configured and modified by electrostatic gating. This electrical control enables a single device to have multiple functionalities. Here, we report ambipolar monolayer WSe2 devices in which two local gates are used to define a p-n junction within the WSe2 sheet. With these electrically tunable p-n junctions, we demonstrate both p-n and n-p diodes with ideality factors better than 2. Under optical excitation, the diodes demonstrate a photodetection responsivity of 210 mA W(-1) and photovoltaic power generation with a peak external quantum efficiency of 0.2%, promising values for a nearly transparent monolayer material in a lateral device geometry. Finally, we demonstrate a light-emitting diode based on monolayer WSe2. These devices provide a building block for ultrathin, flexible and nearly transparent optoelectronic and electronic applications based on ambipolar dichalcogenide materials.


Assuntos
Nanotubos de Carbono , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Semicondutores , Energia Solar , Compostos de Tungstênio
19.
Zhonghua Yi Xue Za Zhi ; 93(17): 1318-20, 2013 May 07.
Artigo em Chinês | MEDLINE | ID: mdl-24029480

RESUMO

OBJECTIVE: To evaluate the application value of multiple phase subtraction imaging of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in common breast tumor. METHODS: All radiographic and MRI data of 72 patients with histological proved common breast tumor were analyzed retrospectively. Prior to an injection of gadolinium-diethylenetriaminepentaacetate (GD-DTPA), 3D mask scans were performed. Then 9 consecutive phases of imaging were acquired. After the drawing of time-signal intensity curve, he first and second phases were selected to perform subtraction with the mask, rebuild 3D maximum intensity projection and analyze the application value of subtracted and 3D maximum intensity projection (MIP) reformation images. Chi-square test was used for the analyses of benign and malignant breast tumors. RESULTS: There were 83 lesions in 72 patients. Among 18 cases of fibro adenoma, 23 lesions had no tumor vessel. For the detecting ratio of lesions, the first and second phase subtraction imaging had no statistics difference. Only one intraductal papilloma with ductal carcinoma in situ (DCIS) had tumor vessel in 4 intraductal papilloma patients. Among 5 DCIS cases, one of them had small curved tumor vessel. And 51 lesions were found in 45 infiltrating ductal carcinoma (IDC) cases. Tumor vessels could be seen in all IDC cases. And 37 cases had multiple tumor vessels while 8 cases had single tumor vessel. When the first phase was used for subtraction, 36 lesions were found. On the other hand, 51 lesions were found in the second phase subtraction. There were significant differences between them. CONCLUSION: No significant differences exist in benign breast tumor on differential phase subtraction images of DCE-MRI, but there are significant differences in malignant breast tumor. It is very important to detect the lesions and show the tumor vessels by rebuilding multiple phase subtraction.


Assuntos
Angiografia Digital , Neoplasias da Mama/diagnóstico , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Feminino , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
20.
Nano Lett ; 13(9): 4212-6, 2013 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-23930826

RESUMO

We report electronic transport measurements of devices based on monolayers and bilayers of the transition-metal dichalcogenide MoS2. Through a combination of in situ vacuum annealing and electrostatic gating we obtained ohmic contact to the MoS2 down to 4 K at high carrier densities. At lower carrier densities, low-temperature four probe transport measurements show a metal-insulator transition in both monolayer and bilayer samples. In the metallic regime, the high-temperature behavior of the mobility showed strong temperature dependence consistent with phonon-dominated transport. At low temperature, intrinsic field-effect mobilities approaching 1000 cm(2)/(V·s) were observed for both monolayer and bilayer devices. Mobilities extracted from Hall effect measurements were several times lower and showed a strong dependence on density, likely caused by screening of charged impurity scattering at higher densities.


Assuntos
Molibdênio/química , Soro/química , Transporte de Elétrons , Metais/química , Temperatura
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