Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 144
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Cytometry A ; 105(4): 266-275, 2024 04.
Artigo em Inglês | MEDLINE | ID: mdl-38111162

RESUMO

In biomedicine, the automatic processing of medical microscope images plays a key role in the subsequent analysis and diagnosis. Cell or nucleus segmentation is one of the most challenging tasks for microscope image processing. Due to the frequently occurred overlapping, few segmentation methods can achieve satisfactory segmentation accuracy yet. In this paper, we propose an approach to separate the overlapped cells or nuclei based on the outer Canny edges and morphological erosion. The threshold selection is first used to segment the foreground and background of cell or nucleus images. For each binary connected domain in the segmentation image, an intersection based edge selection method is proposed to choose the outer Canny edges of the overlapped cells or nuclei. The outer Canny edges are used to generate a binary cell or nucleus image that is then used to compute the cell or nucleus seeds by the proposed morphological erosion method. The nuclei of the Human U2OS cells, the mouse NIH3T3 cells and the synthetic cells are used for evaluating our proposed approach. The quantitative quantification accuracy is computed by the Dice score and 95.53% is achieved by the proposed approach. Both the quantitative and the qualitative comparisons show that the accuracy of the proposed approach is better than those of the area constrained morphological erosion (ACME) method, the iterative erosion (IE) method, the morphology and watershed (MW) method, the Generalized Laplacian of Gaussian filters (GLGF) method and ellipse fitting (EF) method in separating the cells or nuclei in three publicly available datasets.


Assuntos
Algoritmos , Núcleo Celular , Humanos , Animais , Camundongos , Células NIH 3T3 , Microscopia , Processamento de Imagem Assistida por Computador/métodos
2.
Opt Express ; 32(7): 11363-11376, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38570985

RESUMO

Magneto-optical effects, which have been known for over a century, are among the most fundamental phenomena in physics and describe changes in the polarization state of light when it interacts with magnetic materials. When a polarized plane wave propagates in or through a homogeneous and isotropic transparent medium, it is generally accepted that its transverse polarization structure remains unchanged. However, we show that a strong radial polarization component can be generated when an azimuthally polarized sine-Gaussian plane wave is tightly focused by a high numerical aperture lens, resulting in a magneto-optical-like effect that does not require external magnetic field or magnetic medium. Calculations show that the intensity structure and polarization distribution of the highly confined electric field strongly depend on the parameters m and φ0 in the sinusoidal term, where m can be used to control the number of the multifocal spots and φ0 can be used to control the position of each focal spot. Finally, we show that this peculiar electric field distribution can be used to realize multiple particles trapping with controllable numbers and locations.

3.
Graefes Arch Clin Exp Ophthalmol ; 262(6): 1765-1776, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38231247

RESUMO

PURPOSE: To investigate the distinct characteristics between young and elderly polypoidal choroidal vasculopathy (PCV) patients based on the pachy- or non-pachychoroid phenotypes. METHODS: PCV patients treated with intravitreal injections of Conbercept based on the 3 + PRN regimen from 27 centers of China PCV Research Alliance were included. Patients were categorized into the young and the elderly aged group based on the cut-off point determined using the Youden method according to the pachychoroid phenotypes. The characteristics of past medical history, lifestyle factors, fundus manifestations, and treatment response between the subgroups were analyzed. RESULTS: Three hundred eight eligible patients were included. Multivariate logistic regression showed a significant association between age and PCV subtype classification (OR = 0.921, P = 0.002). A cutoff age of 64.5 effectively distinguished between pachychoroid PCV and non-pachychoroid PCV (P < 0.001). Elderly PCV patients had a higher incidence of hypertension history (P = 0.044) but a lower incidence of diabetes history (P = 0.027). In terms of lifestyle, smoking history (P = 0.015) and staying up late (P = 0.004) were more significant in the young group of PCV patients. For clinical characteristics, the proportion of hemorrhagic PCV in the young group was significantly higher (P = 0.038), with a higher proportion of sharp-peaked PED (P = 0.049), thicker choroid (P < 0.001) but a lower portion of double-layer sign (P = 0.023) in OCT. Both groups showed significant anatomical changes compared to baseline in each follow-up period (P < 0.05), with the young group having a higher proportion of good anatomical response after the first injection (P = 0.009). CONCLUSION: PCV patients stratified by subtype exhibit distinct characteristics between the young and elderly groups.


Assuntos
Corioide , Angiofluoresceinografia , Fundo de Olho , Injeções Intravítreas , Fenótipo , Pólipos , Tomografia de Coerência Óptica , Acuidade Visual , Humanos , Masculino , Feminino , Idoso , Pessoa de Meia-Idade , Angiofluoresceinografia/métodos , Corioide/irrigação sanguínea , Pólipos/diagnóstico , Pólipos/tratamento farmacológico , Tomografia de Coerência Óptica/métodos , Estudos Retrospectivos , Seguimentos , Neovascularização de Coroide/diagnóstico , Neovascularização de Coroide/tratamento farmacológico , Doenças da Coroide/diagnóstico , Inibidores da Angiogênese/administração & dosagem , Inibidores da Angiogênese/uso terapêutico , Idoso de 80 Anos ou mais , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Vasculopatia Polipoidal da Coroide
4.
Appl Opt ; 63(3): 865-873, 2024 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-38294403

RESUMO

In this paper, a high-quality germanene-polyvinyl alcohol (PVA) saturable absorber (SA) with a modulation depth of 3.05% and a saturation intensity of 17.95M W/c m 2 was prepared. Stable conventional mode-locking and harmonic mode-locking (HML) were achieved in germanene-based Er-doped fiber lasers (EDFL) using dispersion management techniques. In a cavity with a net dispersion value of -0.22p s 2, the conventional soliton had a center wavelength of 1558.2 nm, a repetition frequency of 19.09 MHz, and a maximum 3 dB spectrum bandwidth of 3.5 nm. The highest repetition frequencies achieved in cavities with net dispersion values of -2.81p s 2, -1.73p s 2, and -1.09p s 2 were 9.48 MHz, 12.75 MHz, and 12.10 MHz for HML, respectively. Furthermore, the effects of dispersion, power, and the polarization state on HML were systematically investigated. Our research results fully demonstrate the capability of germanene as an optical modulator in generating conventional mode-locked and harmonic mode-locked solitons. This provides meaningful references for promoting its application in ultrafast fiber lasers.

5.
Ophthalmic Res ; 67(1): 85-95, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38109862

RESUMO

INTRODUCTION: The aims of the study were to investigate whether first-dose efficacy can predict third-dose anatomical response and analyze the risk factors for first-dose response of polypoidal choroidal vasculopathy (PCV) patients. METHODS: We retrospectively reviewed patients' medical records from 27 centers of China PCV Research Alliance. PCV patients treated with intravitreal injections of conbercept (IVC) based on the 3+ pro re nata regimen (three initial monthly injections, followed by injections as needed) with complete 3-month injection data were included. Response correlations, risk factor associations, changes in central macular thickness (CMT) or best-corrected visual acuity (BCVA), and number of injections in the first year of follow-up were evaluated separately in the pachy-PCV and non-pachy-PCV phenotypes. RESULTS: Overall, 165 eligible patients were included. There was a significant correlation between first-dose and third-dose anatomical response in pachy-PCV or non-pachy-PCV patients (rs = 0.611, p < 0.001; rs = 0.638, p < 0.001). Multivariate analysis revealed associations of good first-dose anatomical response in pachy-PCV patients with baseline CMT with a predicted area under the curve (AUC) of 0.847, while a good response in non-pachy-PCV patients was associated with baseline BCVA, baseline CMT, pigment epithelial detachment (PED) height, higher proportion of intraretinal fluid, and lower PED minimum diameter with a predicted AUC of 0.940. CMT in the good first-dose response group was significantly decreased from baseline at all first-year follow-up visits in both groups (p < 0.001), and mean BCVA was improved in the good versus poor first-dose anatomical response group (5.4 vs. 1.6 ETDRS letters in pachy-PCV, 10.6 vs. 7.4 letters in non-pachy-PCV) after the third injection. No significant difference was observed in the number of injections in the first year of follow-up between different response groups. CONCLUSION: In PCV patients receiving IVC, the first- and third-dose responses are significantly correlated, and different factors influence the first-dose response in different subtypes of PCV.


Assuntos
Resinas Acrílicas , Hidrazinas , Pólipos , Descolamento Retiniano , Humanos , Inibidores da Angiogênese/uso terapêutico , Vasculopatia Polipoidal da Coroide , Estudos Retrospectivos , Resultado do Tratamento , Descolamento Retiniano/etiologia , Fatores de Risco , Injeções Intravítreas , Tomografia de Coerência Óptica , Angiofluoresceinografia , Seguimentos , Pólipos/diagnóstico , Pólipos/tratamento farmacológico , Pólipos/complicações
6.
Angew Chem Int Ed Engl ; : e202407121, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38775229

RESUMO

Electrocatalytic hydrogenation of unsaturated aldehydes to unsaturated alcohols is a promising alternative to conventional thermal processes. Both the catalyst and electrolyte deeply impact the performance. Designing the electrode-electrolyte interface remains challenging due to its compositional and structural complexity. Here, we employ the electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) as a reaction model. The typical cationic surfactant, cetyltrimethylammonium bromide (CTAB), and its analogs are employed as electrolyte additives to tune the interfacial microenvironment, delivering high-efficiency hydrogenation of HMF and inhibition of the hydrogen evolution reaction (HER). The surfactants experience a conformational transformation from stochastic distribution to directional assembly under applied potential. This oriented arrangement hampers the transfer of water molecules to the interface and promotes the enrichment of reactants. In addition, near 100 % 2,5-bis(hydroxymethyl)furan (BHMF) selectivity is achieved, and the faradaic efficiency (FE) of the BHMF is improved from 61 % to 74 % at -100 mA cm-2. Notably, the microenvironmental modulation strategy applies to a range of electrocatalytic hydrogenation reactions involving aldehyde substrates. This work paves the way for engineering advanced electrode-electrolyte interfaces and boosting unsaturated alcohol electrosynthesis efficiency.

7.
Opt Express ; 31(6): 10176-10190, 2023 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-37157571

RESUMO

With the advances in the field of ultrafast photonics occurring so fast, the demand for optical modulation devices with high performance and soliton lasers which can realize the evolution of multiple soliton pulses is gradually increasing. Nevertheless, saturable absorbers (SAs) with appropriate parameters and pulsed fiber lasers which can output abundant mode-locking states still need to be further explored. Due to the special band gap energy values of few-layer indium selenide (InSe) nanosheets, we have prepared a SA based on InSe on a microfiber by optical deposition. In addition, we demonstrate that our prepared SA possesses a modulation depth and saturable absorption intensity about 6.87% and 15.83 MW/cm2, respectively. Then, multiple soliton states are obtained by dispersion management techniques, including regular solitons, and second-order harmonic mode-locking solitons. Meanwhile, we have obtained multi-pulse bound state solitons. We also provide theoretical basis for the existence of these solitons. The results of the experiment show that the InSe has the potential to be an excellent optical modulator because of its excellent saturable absorption properties. This work also is important for improving the understanding and knowledge of InSe and the output performance of fiber lasers.

8.
Opt Express ; 31(16): 26145-26155, 2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-37710482

RESUMO

We proposed an erbium-doped fiber laser mode-locked with a MoxW1-xTe2-based nonlinear optical modulator for the first time to our best knowledge. This fiber laser can deliver bright pulses, bright-dark pulse pairs, dark pulses, bright-dark-bright pulses, and dark-dark-bright pulses. The modulation depth and saturation intensity of the MoxW1-xTe2-based saturable absorber were about 7.8% and 8.6 MW/cm2, respectively. When 10% of the laser in the cavity was output, conventional soliton pulses with central wavelength of 1560.1 nm can be obtained in the cavity. When 70% of the laser was output, dual-wavelength domain-wall dark pulses appeared in the laser cavity. This experiment revealed that an appropriate increase in the ratio of output energy can improve the chance of dark pulses in fiber lasers. The mode-locking states in this fiber laser can evolve with each other between bright pulses, bright-dark pulse pairs and dark pulses by adjusting the polarization controller. The results indicated that the MoxW1-xTe2 can be used to make modulators for generating dark pulses. Furthermore, our work will be of great help to improve the chance of the generation of dark pulse in fiber lasers.

9.
Opt Lett ; 48(9): 2214-2217, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-37126237

RESUMO

A dual-shearing interferometer (DSI) for multimodal hyperspectral imaging is presented. Two orthogonally stacked pairs of coherent beams are generated by a pair of novel, to the best of our knowledge, birefringent lateral shearing splitters. Consequently, two sets of interferograms with full pixel resolution are captured alternately in a time sequence in the double Nyquist frequency mode. Modals of dual-field-of-view hyperspectral imaging and differential-polarization hyperspectral imaging are introduced, and verification experiments are performed. The feasibility of other modals is discussed. The proposed method can effectively improve the instrument's performance in terms of the field of view, polarization, spectral resolution, and spectral range.

10.
Phys Chem Chem Phys ; 25(16): 11545-11554, 2023 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-37039540

RESUMO

Monolayer (ML) PtSe2 is a two-dimensional (2D) semiconductor with a modest band gap and high carrier mobility, and it is a promising 2D material for electronic devices. Finding suitable metal electrodes is a key factor in fabricating high-performance PtSe2 field effect transistors (FETs). In this study, a series of 2D metals, transition metal dichalcogenides (NbSe2, TaS2), borophene, and MXenes (V2C(OH)2, V2CF2, Nb2C(OH)2, Nb2CF2, Nb2CO2, Hf2C(OH)2, Hf2CF2) were used as electrodes for FET fabrication. The interfacial electronic properties of electrodes and PtSe2 were studied in both the vertical and lateral directions using the ab initio method. In the vertical direction, PtSe2 formed ohmic contacts with most of the 2D metals except for Nb2CF2 and Hf2CF2. Specifically, in the cases of Nb2CF2 and Hf2CF2, p- and n-type Schottky contacts were formed with Schottky barrier heights (SBHs) of 0.48 eV and 0.02 eV, respectively. In the lateral direction, PtSe2 with contacting Hf2CF2 and V2C(OH)2 electrodes formed n-type Schottky contacts with SBHs of 0.14 eV and 0.09 eV, respectively. In the cases of TaS2 and Nb2CF2 electrodes, p-type Schottky contacts with SBHs of 0.35 eV and 0.29 eV, respectively, were formed. Moreover, n-type ohmic contacts were observed when Hf2C(OH)2 and Nb2C(OH)2 electrodes were applied, and p-type ohmic contacts were formed when borophene, NbSe2, Nb2CO2, and V2CF2 electrodes were used. This work reports a systematic investigation of ML PtSe2-2D metal interfaces and serves as a practical guide for selecting electrode materials for PtSe2 FETs.

11.
J Nat Prod ; 86(12): 2621-2629, 2023 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-37984868

RESUMO

Six new squalene derived polyether glycosides, onygenaleosides A-F (1-6), that possess a 6/5 bicyclic fused ring skeleton were isolated from the cultures of Onygenales sp. YX1425, along with two known analogues (7 and 8). The planar structures of the new compounds were elucidated based on analysis of NMR and MS spectroscopy data, and the absolute configuration of 1 was determined by the advanced Mosher method and quantum chemical calculations. Compound 2 was active against Spodoptera frugiperda with an LC50 value of 193.4 ± 1.1 µg/mL.


Assuntos
Inseticidas , Triterpenos , Glicosídeos/farmacologia , Glicosídeos/química , Triterpenos/farmacologia , Triterpenos/química , Inseticidas/farmacologia , Espectroscopia de Ressonância Magnética/métodos , Esqueleto , Estrutura Molecular
12.
Graefes Arch Clin Exp Ophthalmol ; 261(3): 669-679, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36210375

RESUMO

PURPOSE: To compare the three-dimensional (3D) heads-up surgery with the traditional microscopic (TM) surgery for various vitreoretinal diseases. METHODS: A medical record review of patients that underwent 3D heads-up or TM vitreoretinal surgeries was performed from May 2020 to October 2021 in this retrospective case-control study. Main outcome measures included surgery-related characteristics, efficacy, safety, and satisfaction feedback from the surgical team. RESULTS: A total of 220 (47.6%) and 242 (52.4%) eyes were included in the 3D and TM groups, respectively. The 3D heads-up system significantly benefits delicate surgical steps, like the epiretinal membrane (ERM) peeling for ERM and internal limiting membrane peeling for idiopathic macular holes (P < 0.05). The 3D heads-up system could facilitate a significantly better visual outcome for pathologic myopic foveoschisis (P = 0.049), while no difference by TM surgery (P = 0.45). For the satisfaction feedback, the 3D heads-up system was rated significantly higher in most subscales and the overall score (P < 0.05). The surgeons' ratings on operating accuracy and the first assistants' rating on operating accuracy and operation cooperation were significantly higher in the TM group than in the 3D group (P < 0.05). Besides that, the 3D heads-up surgery was comparable with TM surgery in the surgery-related characteristics, choice of tamponades, postoperative VA, primary anatomic success, and perioperative complications (P > 0.05). CONCLUSION: The efficacy and safety of the 3D heads-up surgery were generally comparable to the TM surgery. The 3D heads-up system could significantly benefit delicate surgical steps and achieve better surgical team satisfaction.


Assuntos
Membrana Epirretiniana , Oftalmopatias , Perfurações Retinianas , Humanos , Estudos Retrospectivos , Estudos de Casos e Controles , Imageamento Tridimensional/métodos , Oftalmopatias/cirurgia , Perfurações Retinianas/diagnóstico , Perfurações Retinianas/cirurgia , Membrana Epirretiniana/diagnóstico , Membrana Epirretiniana/cirurgia , Vitrectomia/métodos
13.
Appl Opt ; 62(8): 1921-1926, 2023 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-37133075

RESUMO

In this paper, an indium antimonide (InSb) saturable absorber (SA) was successfully fabricated. The saturable absorption properties of the InSb SA were studied, and they show a modulation depth and a saturable intensity of 5.17% and 9.23M W/c m 2, respectively. By employing the InSb SA and building the ring cavity laser structure, the bright-dark soliton operations were successfully obtained by increasing the pump power to 100.4 mW and adjusting the polarization controller. As the pump power increased from 100.4 to 180.3 mW, the average output power increased from 4.69 to 9.42 mW, the corresponding fundamental repetition rate was 2.85 MHz, and the signal-to-noise ratio was 68 dB. The experimental results show that InSb with excellent saturable absorption characteristics can be used as a SA to obtain pulse lasers. Therefore, InSb has important potential in fiber laser generation, further applications in optoelectronics, laser distance ranging, and optical fiber communication, and it can be widely developed.

14.
Lett Appl Microbiol ; 76(4)2023 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-37073087

RESUMO

Isocitrate lyase (ICL), as the key enzyme in the glyoxylate metabolic pathway, plays an important role in metabolic adaptation to environmental changes. In this study, metagenomic DNA from the soil and water microorganism collected from the Dongzhai Harbor Mangroves (DHM) reserve, in Haikou City, China, was high-throughput sequenced using an Illumina HiSeq 4000 platform. The icl121 gene, encoding an ICL with the highly conserved catalytic pattern IENQVSDEKQCGHQD was identified. Then, this gene was subcloned into the pET-30a vector and overexpressed in Escherichia coli BL21 (DE3) cells. The maximum enzymatic activity of the recombinant ICL121 protein is 9.47 × 102 U/mg occurring at pH 7.5 and 37°C. Furthermore, as a metalo-enzyme, ICL121 can utilize the appropriate concentrations of Mg2+, Mn2+, and Na+ ion as cofactors to exhibit high enzymatic activity. In particular, the novel metagenomic-derived icl121 gene displayed distinct salt tolerance (NaCl) and might be useful for generating salt-tolerant crops in the future.


Assuntos
Isocitrato Liase , Áreas Alagadas , Isocitrato Liase/química , Isocitrato Liase/genética , Isocitrato Liase/metabolismo , Escherichia coli/genética , Sequência de Bases , Proteínas Recombinantes/genética
15.
Angew Chem Int Ed Engl ; 62(33): e202307848, 2023 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-37378584

RESUMO

The site isolation strategy has been employed in thermal catalytic acetylene semihydrogenation to inhibit overhydrogenation and C-C coupling. However, there is a dearth of analogous investigations in electrocatalytic systems. In this work, density functional theory (DFT) simulations demonstrate that isolated Cu metal sites have higher energy barriers on overhydrogenation and C-C coupling. Following this result, we develop Cu single-atom catalysts highly dispersed on nitrogen-doped carbon matrix, which exhibit high ethylene selectivity (>80 % Faradaic efficiency for ethylene, <1 % Faradaic efficiency for C4 , and no ethane) at high concentrations of acetylene. The superior performance observed in the electrocatalytic selective hydrogenation of acetylene can be attributed to the weak adsorption of ethylene intermediates and highly energy barriers on C-C coupling at isolated sites, as confirmed by both DFT calculations and experimental results. This study provides a comprehensive understanding of the isolated sites inhibiting the side reactions of electrocatalytic acetylene semihydrogenation.

16.
Small ; 18(41): e2203152, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36026553

RESUMO

The continuous white-light emission of carbon dots (CDs) can be applied to producing multicolor laser emissions by one single medium. Meanwhile, the solid-state emission greatly contributes to its practical application. In this work, a strategy to realize the in-situ hybridization of silane-functionalized CDs (SiCDs) and 1,3,5-benzenetricarboxylic acid trimethyl ester (Et3BTC) by a one-pot solvothermal method is reported. Significantly, the SiCDs/Et3BTC hybrid crystals exhibit ultra-broadband random laser emission over the near ultraviolet-visible region under 265 nm nanosecond pulsed laser excitation. The wavelength region of laser emission is achieved from 315 to 600 nm within an emission band of CDs-based materials. It is worth noting that the wavelength range of the laser is wider than the previously reported works. It is proposed that the continuous white-light emission of SiCDs caused by multiple fluorescence centers mainly gives rise to the broadband random laser emission. Moreover, the crystals are conducive to forming resonance and realizing solid-state laser emission. This in-situ method is expected to enable a more convenient, cheaper, and greener approach to prepare luminescent hybrids for application in multicolor laser displays, multi-level laser anti-counterfeiting, supercontinuum light sources, and so on.

17.
Opt Express ; 30(23): 41774-41783, 2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36366645

RESUMO

Based on the dual-resonance principle around the dispersion turning point, a scheme of chiral long-period fiber gratings (CLPGs) formed by twisting a high-birefringence (Hi-Bi) fiber is herein proposed to realise ultra-broadband flat-top circular polarizers. The coupling bandwidth is approximately seven times larger than that of traditional CLPGs. In addition, by introducing chirp characteristics in these CLPGs, an ultra-broadband flat-top circular polarizer with ∼200 nm@3 dB was conveniently achieved. Subsequently, by optimising the chirped CLPGs, a circular polarizer with a bandwidth extinction ratio of approximately 30 dB and a high level of ∼100 nm at 1 dB was realised. It was shown that the mode-controlling performances of the CLPGs can be remarkably improved, which has significant applications in light-field regulation. Finally, for the first time, it was proved that the CLPG cannot generate a vortex beam.

18.
Opt Lett ; 47(7): 1879-1882, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35363759

RESUMO

Ultraviolet solid-state light sources, especially in the short-wave ultraviolet band, are attracting great attention for potential applications in high-density optical data storage, biomedical research, and water and air purification and sterilization. As one of the means to generate solid-state short-wavelength lasers, upconversion technology, which can transform a low-energy photon to a high-energy photon, has a simple structure and does not require strict phase-matching conditions. However, because of the high non-radiative decay rate during multiphoton absorption process, the short-wave upconversion ultraviolet lasing is still difficult to achieve. Here, under 450 nm blue laser excitation, we have successfully obtained ultraviolet C random lasing from a Pr3+ doped YPO4 single crystal via two-photon absorption. Presently, ultraviolet C random lasing with the wavelength range of 230-280 nm is the shortest wavelength for upconversion lasing emission.

19.
Phys Chem Chem Phys ; 24(3): 1849-1859, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-34988568

RESUMO

The spin-resolved transport properties of molecular logic devices composed of two Mn porphyrin molecules connected to each other via a six-carbon atomic chain were studied using the non-equilibrium Green's function combined with density functional theory. The molecules were symmetrically connected to armchair graphene nanoribbon electrodes through four-carbon atomic chains on the left- and right-hand sides. Our calculations revealed that the spin-resolved current-voltage curves depend on the initial spin setting of the transition metal Mn atoms and carbon atoms on the zigzag edges where the electrodes come in contact with the molecule. By simultaneously regulating the spin orientations of the intermediate functional molecules and the zigzag edges of the armchair graphene nanoribbon electrodes, seven spin polarization configurations were obtained. These configurations were examined in this study considering the spin-related symmetry of molecular junctions. By meticulously selecting different combinations according to the specific input and output signals, YES, NOT, OR, NOR, and XOR multifarious spin logic devices were created. The findings of this study are expected to contribute toward the extension of molecular junction functions in future spintronic integrated circuit design and further miniaturization.

20.
Graefes Arch Clin Exp Ophthalmol ; 260(2): 439-450, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34453606

RESUMO

PURPOSE: To estimate the clinical characteristics of retinal arterial macroaneurysms (RAM) and evaluate the prognosis of different interventions. METHODS: This study is a meta-analysis. The databases PubMed, EMBASE, and Ovid from inception to January 2021 were searched to identify the relevant studies. R software version 3.6.3 was used to perform the statistical analyses. Results in proportion with 95% confidence interval were calculated by means of Freeman-Tukey variant of arcsine square transformation. RESULTS: Sixty-nine studies involving 1332 patients were finally included. The pooling results indicated that 91% (95% CI [88 ~ 94%]) of the RAM patients were over sixty, 73% (95% CI [68 ~ 77%]) were female, and 73% (95% CI [66 ~ 79%]) have hypertension. By observation, the RAM closure rate was 64% (95% CI [39 ~ 86%]), the visual acuity (VA) improved in 55% (95% CI [40 ~ 71%]) of the patients, and the VA of 64% (95% CI [54 ~ 74%]) hemorrhagic versus 27% (95% CI [15 ~ 41%]) exudative patients improved significantly. By laser, the closure rate was 96% (95% CI [87 ~ 100%]), the VA improved in 73% (95% CI [65 ~ 80%]) of the patients, and the VA of 66% (95% CI [47 ~ 84%]) hemorrhagic versus 35% (95% CI [23 ~ 47%]) exudative patients improved significantly. By anti-VEGF, the closure rate was 98% (95% CI [93 ~ 100%]), the VA improved in 90% (95% CI [74 ~ 100%]) of the patients, and the VA of 58% (95% CI [18 ~ 94%]) hemorrhagic versus 67% (95% CI [31 ~ 96%]) exudative patients improved significantly. CONCLUSION: RAM are most commonly seen in the elderly with a marked female predominance and a strong association with hypertension. Patients receiving laser or anti-VEGF treatments get higher closure rate and better visual prognosis than those with observation alone. Hemorrhagic RAM have a better visual prognosis by observation or laser treatment, while exudative RAM have a better visual prognosis by anti-VEGF treatment.


Assuntos
Macroaneurisma Arterial Retiniano , Idoso , Inibidores da Angiogênese , Feminino , Humanos , Prognóstico , Acuidade Visual
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA