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1.
Sci Rep ; 10(1): 113, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924798

RESUMO

This paper proposes a compact broadband frequency scanning spoof surface plasmon polariton (SSPP) based design for efficient endfire radiations with high field confinement. Through the dispersion engineering, highly confined field distribution has been obtained in the operating frequency region. The proposed SSPP antenna has achieved a continuous through endfire scanning in the X-band at other operating frequencies which is in general difficult to obtain for SSPP based antennas. In the proposed design methodology, the swore-shaped surface plasmon antenna has both edges corrugated with an array of rectangular grooves which effectively confines the electromagnetic field into a slow travelling wave. The surface impedances along both edges were engineered to be different at operating frequencies as to force the surface current to preferentially flow along either edge of the antenna to a different extent. The design with overall dimensions of (55 × 30) mm2 has achieved a broadband of 4 GHz with high peak measured gain of 9.8 dBi and peak efficiency of about 95 percent in the X-band. The antenna has been further tested experimentally for scanning application of target location also.

2.
Genes (Basel) ; 10(11)2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31752416

RESUMO

Soybean is an important cash crop that is widely used as a source of vegetable protein and edible oil. The regeneration ability of soybean directly affects the application of biotechnology. In this study, we used the exogenous hormone 2,4-D to treat immature embryos. Different levels of somatic incidence were selected from the chromosome segment substitution lines (CSSLs) constructed by SN14 and ZYD00006. Transcriptome sequencing of extreme materials was performed, and 2666 differentially expressed genes were obtained. At the same time, a difference table was generated by combining the data on CSSL rearrangement. In the extreme materials, a total of 93 differentially expressed genes were predicted and were then analyzed by cluster analysis and Gene Ontology (GO) annotation. After screening and annotating the target genes, three differentially expressed genes with hormone pathways were identified. The expression patterns of the target genes were verified by real-time quantitative PCR (qRT-PCR). Haplotype polymorphism detection and linkage disequilibrium analysis were performed on the candidate gene Glyma.09g248200. This study provided more information on the regulation network of soybean somatic embryogenesis and regeneration processes, and further identified important genes in the soybean regeneration process and provided a theoretical basis for accelerating the application of biotechnology to soybean for improving its breeding efficiency.

3.
Phys Chem Chem Phys ; 21(42): 23697-23704, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31633133

RESUMO

The desolvation effect of ions plays an important role in adjusting the capacity of supercapacitors and has attracted considerable attention after its discovery. Here, first-principles calculations were conducted to calculate the reaction energies of ions, water, and hydrated ions in bilayer graphene (BG) with different interlayer spacings (d) and to explore the desolvation behaviors of H+, Li+, Na+, and K+ ions. The calculated results showed that H+ can only exist in the state of H3O+ in AA-stacking BG, and desolvation exists only in the case of AB-stacking BG. The complete desolvation size for H+ ions in the AB-stacking system reached 5.6 Å, which was the largest desolvation size of the four ions studied. The critical desolvation sizes of Li+, Na+, and K+ in the BG layers of AA- and AB-stacking increased sharply as a consequence of the increasing ionic radius. However, the complete desolvation sizes of all three ions were in the range of 4-5 Å and with the increase in ionic radius, the complete desolvation sizes showed a reverse tendency. The complete desolvation size of Na+ in AB-stacking BG was slightly larger than that in AA-stacking BG. Further analysis presented that the ionic radii of H+, Li+, Na+, and K+ ions make a dominant contribution to the critical size of desolvation. Our present results provide useful information for improving the capacity of supercapacitors by precisely matching the pore structure and electrolyte through the adjustment of the pore structure of carbon materials.

4.
Nan Fang Yi Ke Da Xue Xue Bao ; 38(10): 1171-1178, 2018 Sep 30.
Artigo em Chinês | MEDLINE | ID: mdl-30377133

RESUMO

OBJECTIVE: To identify the predictive factors for differentiating pancreatic ductal adenocarcinoma (PDAC) from other neoplastic solid pancreatic lesions and assess the accuracy of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for diagnosis of PDAC. METHODS: We retrospectively analyzed the clinical data of patients referred for EUS-FNA evaluation of pancreatic lesions in the Digestive Endoscopic Center of Nanfang Hospital between January, 2009 and May, 2016. The cases with unknown diagnosis, missing data, repeated punctures, cystic lesions and benign lesions were excluded from the analysis. The positivity rates of EUS-FNA were compared between patients with PDAC and those with non-PDAC lesions, and the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of EUS-FNA were assessed in the diagnosis of PDAC. Univariate and multivariate logistic regression analyses were used to identify the factors for differentiating PDAC from non-PDAC lesions based on the demographic characteristics, clinical presentations, laboratory data, and endoscopic ultrasonography imaging features of the patients. RESULTS: Among the 75 patients with solid neoplastic pancreatic lesions, 54 (72.0%) were found to have PDAC and 21 (28.0%) had non-PDAC lesions. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EUS-FNA for the diagnosis of PDAC were 77.8%, 100.0%, 100.0%, 63.6% and 84.0%, respectively. No significant difference was found in the positivity rate of EUS-FNA between patients with PDAC and those with non-PDAC lesions (77.8% vs 76.2%, P > 0.05). Multivariate regression analysis identified abdominal pain (OR=5.163, 95%CI: 1.093-24.389, P=0.038), lesion size (OR=0.926, 95%CI: 0.877-0.978, P=0.006), characteristics of the solid lesions (OR=7.105, 95%CI: 1.440-35.043, P=0.016), and evidence of metastases (OR=6.165, 95%CI: 1.332-28.533, P=0.020) as the independent factors for predicting PDAC. CONCLUSIONS: The pretest characteristics including abdominal pain, evidence of metastases, and lesion size and lesion characteristics defined by endoscopic ultrasonography findings can reliably predict a diagnosis of PDAC. EUS-FNA has a high sensitivity and a high specificity for the diagnosis of PDAC.


Assuntos
Carcinoma Ductal Pancreático/diagnóstico , Carcinoma Ductal Pancreático/patologia , Aspiração por Agulha Fina Guiada por Ultrassom Endoscópico , Pâncreas/patologia , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/patologia , Diagnóstico Diferencial , Endossonografia , Humanos , Análise de Regressão , Estudos Retrospectivos , Sensibilidade e Especificidade , Avaliação de Sintomas
5.
Polymers (Basel) ; 10(1)2018 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-30966107

RESUMO

We have investigated the dispersion state of a perfluorosulfonated ionomer (PFSI; Nafion®) in aqueous dispersion and the effect of methanol (MeOH) added to the aqueous dispersion by small-angle X-ray scattering (SAXS) as well as static and dynamic light scattering (SLS and DLS, respectively). Although both electrostatic and hydrophobic interactions of PFSI are expected to be strong in the dispersions, SAXS profiles obtained were satisfactorily fitted by the spherical particle model of a bimodal molar mass distribution. The rod-like aggregate model proposed in previous papers was denied at least for the present PFSI dispersion. Although the SAXS profiles exhibited a weak peak and the auto-correlation functions of DLS showed a log-time decay by the "repulsive cage effect" due to the long-ranged electrostatic interaction among PFSI particles, the concentration dependence of SLS results was probably normal because the cancellation of the electrostatic and hydrophobic interactions. The addition of MeOH into the aqueous dispersion of PFSI weakened both the hydrophobic and electcrostatic interactions of PFSI, and it is rather difficult to classify whether MeOH is a good or poor solvent (dispersant) for PFSI.

6.
Phys Chem Chem Phys ; 19(48): 32708-32714, 2017 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-29199287

RESUMO

Lithium-sulfur (Li-S) batteries have attracted increasing attention due to their high theoretical capacity, being a promising candidate for portable electronics, electric vehicles and large-scale energy storage. The interactions of bilayer structured graphitic C3N4 (bi-C3N4) with S8, lithium polysulfides (LiPSs), 1,3-dioxolane, 1,2-dimethoxyethane and tetrahydrofuran ether-based solvents have been studied using first-principles calculations. It has been found that the (micropore-scale) interlayer of bi-C3N4 shows intimate contact and strong binding with S8 and LiPSs due to the formation of chemical Li-N bonds. The incorporation of soluble LiPSs by the wrinkled layers of bi-C3N4 with 5.5-7.2 Å interlayer pores can suppress the shuttling effect. The interlayer ultramicropores with interlayer distances of <4 Å can accommodate the small Li2S2 and Li2S molecules, and impede the irreversible reaction between the solvents and the LiPSs. The calculated energy gap of bi-C3N4 decreases to be narrow during lithiation. Our results can provide a guideline for promoting the electrochemical performance of microporous g-C3N4/sulfur composites for Li-S batteries.

7.
PLoS One ; 12(4): e0175656, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28403182

RESUMO

Plant regeneration can occur via in vitro tissue culture through somatic embryogenesis or de novo shoot organogenesis. Transformation of soybean (Glycine max) is difficult, hence optimization of the transformation system for soybean regeneration is required. This study investigated ENHANCER OF SHOOT REGENERATION 1 (GmESR1), a soybean transcription factor that targets regeneration-associated genes. Sequence analysis showed that GmESR1 contained a conserved 57 amino acid APETALA 2 (AP2)/ETHYLENE RESPONSE FACTOR (ERF) DNA-binding domain. The relative expression level of GmESR1 was highest in young embryos, flowers and stems in the soybean cultivar 'Dongnong 50'. To examine the function of GmESR1, transgenic Arabidopsis (Arabidopsis thaliana) and soybean plants overexpressing GmESR1 were generated. In Arabidopsis, overexpression of GmESR1 resulted in accelerated seed germination, and seedling shoot and root elongation. In soybean overexpression of GmESR1 also led to faster seed germination, and shoot and root elongation. GmESR1 specifically bound to the GCC-box. The results provide a foundation for the establishment of an efficient and stable transformation system for soybean.


Assuntos
Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Soja/fisiologia , Fatores de Transcrição/genética , Sequência de Aminoácidos , Arabidopsis , Sequência de Bases , Sequência Conservada , Expressão Gênica , Modelos Moleculares , Filogenia , Proteínas de Plantas/biossíntese , Proteínas de Plantas/química , Ligação Proteica , Domínios Proteicos , Regeneração , Alinhamento de Sequência , Fatores de Transcrição/biossíntese , Fatores de Transcrição/química
8.
Soft Matter ; 12(34): 7150-8, 2016 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-27470971

RESUMO

Nonionic surfactant-activated microgels (SAMs), composed of hydrophobic alkyl acrylates and hydrophilic hydroxyalkyl esters that utilize the effects of surfactant mediated swelling and interaction to provide pH-independent rheological properties, were previously reported as a new pathway to the rheology modification of surfactant solutions. Crosslinking was shown to play an important role in the properties of these soft microgel systems. To understand the impact of crosslinking chemistry on SAM polymers, we have compared two types of SAM polymers: a conventionally crosslinked SAM polymer via allyl pentaerythritol and a novel SAM polymer, where the surface is self-crosslinked via a reactive surfactant. We have systematically characterized the polymer's swelling, rheology and microstructure in a model system containing the polymer, sodium dodecyl sulfate (SDS) and water. Surface self-crosslinking is demonstrated to be a more effective crosslinking approach to create surfactant-mediated interactions between the microgel particles, resulting in more effective rheology modification. Internal crosslinking hinders both the full swelling of the SAM polymer as well as inter-particle bridging interactions, and is therefore less effective. To our best knowledge, this is the first report on creating a novel surface self-crosslinked microgel via a dual-functional reactive surfactant that interacts with a non-reactive surfactant to create a yield stress fluid.

9.
Biomed Opt Express ; 6(6): 1954-62, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-26114021

RESUMO

Shear wave speed is quantitatively related to tissue viscoelasticity. Previously we reported shear wave tracking at centimetre depths in a turbid optical medium using laser speckle contrast detection. Shear wave progression modulates displacement of optical scatterers and therefore modulates photon phase and changes the laser speckle patterns. Time-resolved charge-coupled device (CCD)-based speckle contrast analysis was used to track shear waves and measure the time-of-flight of shear waves for speed measurement. In this manuscript, we report a new observation of the laser speckle contrast difference signal for dual shear waves. A modulation of CCD speckle contrast difference was observed and simulation reproduces the modulation pattern, suggesting its origin. Both experimental and simulation results show that the dual shear wave approach generates an improved definition of temporal features in the time-of-flight optical signal and an improved signal to noise ratio with a standard deviation less than 50% that of individual shear waves. Results also show that dual shear waves can correct the bias of shear wave speed measurement caused by shear wave reflections from elastic boundaries.

10.
Biomed Opt Express ; 6(1): 63-71, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25657875

RESUMO

Tissue optical and mechanical properties are correlated to tissue pathologic changes. This manuscript describes a dual-mode ultrasound modulated optical imaging system capable of sensing local optical and mechanical properties in reflection geometry. The optical characterisation was achieved by the acoustic radiation force assisted ultrasound modulated optical tomography (ARF-UOT) with laser speckle contrast detection. Shear waves generated by the ARF were also tracked optically by the same system and the shear wave speed was used for the elasticity measurement. Tissue mimicking phantoms with multiple inclusions buried at 11 mm depth were experimentally scanned with the dual-mode system. The inclusions, with higher optical absorption and/or higher stiffness than background, were identified based on the dual results and their stiffnesses were quantified. The system characterises both optical and mechanical properties of the inclusions compared with the ARF-UOT or the elasticity measurement alone. Moreover, by detecting the backward scattered light in reflection detection geometry, the system is more suitable for clinical applications compared with transmission geometry.

11.
Ultrasound Med Biol ; 41(5): 1422-31, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25656747

RESUMO

Phase-change contrast agents in the form of nanoscale droplets can be activated into microbubbles by ultrasound, extending the contrast beyond the vasculature. This article describes simultaneous optical and acoustical measurements for quantifying the ultrasound activation of phase-change contrast agents over a range of concentrations. In experiments, decafluorobutane-based nanodroplets of different dilutions were sonicated with a high-pressure activation pulse and two low-pressure interrogation pulses immediately before and after the activation pulse. The differences between the pre- and post-interrogation signals were calculated to quantify the acoustic power scattered by the microbubbles activated over a range of droplet concentrations. Optical observation occurred simultaneously with the acoustic measurement, and the pre- and post-microscopy images were processed to generate an independent quantitative indicator of the activated microbubble concentration. Both optical and acoustic measurements revealed linear relationships to the droplet concentration at a low concentration range <10(8)/mL when measured at body temperature. Further increases in droplet concentration resulted in saturation of the acoustic interrogation signal. Compared with body temperature, room temperature was found to produce much fewer and larger bubbles after ultrasound droplet activation.


Assuntos
Meios de Contraste/química , Fluorcarbonetos/química , Fluorcarbonetos/efeitos da radiação , Ondas de Choque de Alta Energia , Nanopartículas/química , Nanopartículas/efeitos da radiação , Meios de Contraste/efeitos da radiação , Relação Dose-Resposta à Radiação , Teste de Materiais , Tamanho da Partícula , Transição de Fase , Doses de Radiação
12.
Opt Lett ; 39(6): 1597-600, 2014 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-24690847

RESUMO

Shear wave propagation provides rich information for material mechanical characterization, including elasticity and viscosity. This Letter reports tracking of shear wave propagation in turbid media by laser-speckle-contrast analysis. The theory is described, and a Monte Carlo simulation of light shear wave interaction was developed. Simulation and experiments on tissue-mimicking phantoms agree well and show tracking of shear wave at the phantom surface and at depth as well as multiple shear waves interacting within the object. The relationship between speckle contrast value and shear wave amplitude is also investigated.


Assuntos
Lasers , Modelos Estatísticos , Nefelometria e Turbidimetria/métodos , Resistência ao Cisalhamento , Simulação por Computador , Espalhamento de Radiação
13.
J Biomed Opt ; 18(12): 121511, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24357548

RESUMO

Tissue viscosity is correlated with tissue pathological changes and provides information for tissue characterization. In this study, we report an optical method to track continuous shear-wave propagation at centimeter depths in an optically turbid medium. Shear-wave attenuation coefficients were measured at multiple frequencies using shear-wave laser speckle contrast analysis (SW-LASCA) to quantitatively estimate tissue viscosity using the Voigt model. Shear waves were generated within tissue-mimicking phantoms by an amplitude-modulated ultrasound (modulation frequency: 100 to 600 Hz) and tracked by time-resolved laser speckle contrast difference received on a charged-coupled device camera. Averaged contrast difference over a selected time window was related to shear-wave amplitude and used to calculate the shear-wave attenuation coefficient. Phantoms of varying viscosities (0.1 and 0.3 Pa s) were studied. Attenuation coefficients for different shear-wave frequencies (100 to 600 Hz) were calculated. Derived viscosity values had a maximum standard deviation of 9%, and these values were consistent with the independent measurements reported in a previous study using nonoptical methods.


Assuntos
Técnicas de Imagem por Elasticidade , Viscosidade , Fenômenos Biomecânicos , Elasticidade , Técnicas de Imagem por Elasticidade/instrumentação , Técnicas de Imagem por Elasticidade/métodos , Modelos Biológicos , Imagens de Fantasmas
14.
Ultrasound Med Biol ; 38(9): 1637-45, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22749816

RESUMO

Tissue elasticity is closely related to the velocity of shear waves within biologic tissue. Shear waves can be generated by an acoustic radiation force and tracked by, e.g., ultrasound or magnetic resonance imaging (MRI) measurements. This has been shown to be able to noninvasively map tissue elasticity in depth and has great potential in a wide range of clinical applications including cancer and cardiovascular diseases. In this study, a highly sensitive optical measurement technique is proposed as an alternative way to track shear waves generated by the acoustic radiation force. A charge coupled device (CCD) camera was used to capture diffuse photons from tissue mimicking phantoms illuminated by a laser source at 532 nm. CCD images were recorded at different delays after the transmission of an ultrasound burst and were processed to obtain the time of flight for the shear wave. A differential measurement scheme involving generation of shear waves at two different positions was used to improve the accuracy and spatial resolution of the system. The results from measurements on both homogeneous and heterogeneous phantoms were compared with measurements from other instruments and demonstrate the feasibility and accuracy of the technique for imaging and quantifying elasticity. The relative error in estimation of shear wave velocity can be as low as 3.3% with a spatial resolution of 2 mm, and increases to 8.8% with a spatial resolution of 1 mm for the medium stiffness phantom. The system is shown to be highly sensitive and is able to track shear waves propagating over several centimetres given the ultrasound excitation amplitude and the phantom material used in this study. It was also found that the reflection of shear waves from boundaries between regions with different elastic properties can cause significant bias in the estimation of elasticity, which also applies to other shear wave tracking techniques. This bias can be reduced at the expense of reduced spatial resolution.


Assuntos
Técnicas de Imagem por Elasticidade/métodos , Aumento da Imagem/métodos , Algoritmos , Módulo de Elasticidade , Interpretação de Imagem Assistida por Computador , Óptica e Fotônica , Imagens de Fantasmas , Transdutores
15.
J Biomed Opt ; 17(5): 057002, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22612141

RESUMO

The combined use of surface acoustic wave (SAW) and phase-sensitive optical coherence tomography (PhS-OCT) is useful to evaluate the elasticity of layered biological tissues, such as normal skin. However, the pathological tissue is often originated locally, leading to the alternation of mechanical properties along both axial and lateral directions. We present a feasibility study on whether the SAW technique is sensitive to detect the alternation of mechanical property along the lateral direction within tissue, which is important for clinical utility of this technique to localize diseased tissue. Experiments are carried out on purposely designed tissue phantoms and ex vivo chicken breast samples, simulating the localized change of elasticity. A PhS-OCT system is employed not only to provide the ultra-high sensitive measurement of the generated surface waves on the tissue surface, but also to provide the real time imaging of the tissue to assist the elasticity evaluation of the heterogeneous tissue. The experimental results demonstrate that with PhS-OCT used as a pressure sensor, the SAW is highly sensitive to the elasticity change of the specimen in both vertical and lateral directions with a sensing depth of ∼5 mm with our current system setup, thus promising its useful clinical applications where the quantitative elasticity of localized skin diseases is needed to aid in diagnosis and treatment.


Assuntos
Algoritmos , Mama/anatomia & histologia , Mama/fisiologia , Técnicas de Imagem por Elasticidade/métodos , Interpretação de Imagem Assistida por Computador/métodos , Modelos Biológicos , Animais , Galinhas , Simulação por Computador , Módulo de Elasticidade/fisiologia , Aumento da Imagem/métodos , Técnicas In Vitro , Técnicas Fotoacústicas , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Tomografia de Coerência Óptica
16.
J Phys Chem B ; 114(36): 11731-6, 2010 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-20726536

RESUMO

Femtosecond time-resolved absorption spectroscopy has been used to study the excited-state charge transfer dynamics in a set of self-assembled cyclic Fe(II)-bisterpyridine compounds with different π-conjugated ligands. By analyzing the dynamics, the internal conversion process involving a ligand-centered π-π* state to a lower lying metal-to-ligand charge transfer (MLCT) state was investigated. This is followed by intersystem crossing to the lowest MLCT state, which was found to occur at the ∼100 fs time scale. Vibrational cooling in the lowest MLCT state was found to occur on the 10s of femtoseconds time scale. The lowest MLCT state had an excited-state lifetime longer than 5 ns, indicating the possibility of light-induced excited-state spin trapping (LIESST).


Assuntos
Compostos Ferrosos/química , Piridinas/química , Análise Espectral/métodos , Ligantes , Metais/química , Estrutura Molecular , Fatores de Tempo
18.
Science ; 312(5781): 1782-5, 2006 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-16690820

RESUMO

Mathematics and art converge in the fractal forms that also abound in nature. We used molecular self-assembly to create a synthetic, nanometer-scale, Sierpinski hexagonal gasket. This nondendritic, perfectly self-similar fractal macromolecule is composed of bis-terpyridine building blocks that are bound together by coordination to 36 Ru and 6 Fe ions to form a nearly planar array of increasingly larger hexagons around a hollow center.

19.
Chem Commun (Camb) ; (10): 1091-3, 2006 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-16514449

RESUMO

The self-assembly of Oxi-SWNTs, based on terpyridineCu(II) coordination, produces a thermally stable, neutral [(Oxi-SWNT)(tpyCu(II))m]n nanocomposite possessing notable luminscence properties; quantitative disassembly occurred by treatment with aqueous KCN.

20.
J Am Chem Soc ; 127(1): 14-5, 2005 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-15631425

RESUMO

Multicomponent structures were constructed by DNA-directed self-assembling of multiple carbon nanotubes and gold nanoparticles. The work presented here represents an important advance in constructing many multicomponent nanotube structures for multifunctional material and device applications.


Assuntos
DNA de Cadeia Simples/química , Nanotubos de Carbono/química , Ouro/química , Microscopia de Força Atômica , Hibridização de Ácido Nucleico
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