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In Vivo 3D Imaging of Retinal Neovascularization Using Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Imaging
摘要： The pathological process of neovascularization of the retina plays a critical role in causing vision loss in several diseases, including diabetes, retinal vein occlusion, and sickle cell disease. Retinal neovascularization can lead to vitreous hemorrhage and retinal detachment, yet the pathological process of neovascularization is a complex phenomenon under active investigation. Understanding and monitoring retinal neovascularization is critically important in clinical ophthalmology. This study describes a novel multimodal ocular imaging system which combines photoacoustic microscopy (PAM) and a spectral domain optical coherence tomography (SD-OCT) to improve the visualization of retinal neovascularization (RNV), their depth, and the surrounding anatomy in living rabbits. RNV was induced in New Zealand rabbits by intravitreal injection of vascular endothelial growth factor (VEGF). The retinal vasculature before and after injection at various times was monitored and evaluated using multimodal imaging including color fundus photography, fluorescein angiography (FA), OCT, and PAM. In vivo experiments demonstrate that PAM imaging distinctly characterized the location as well as the morphology of individual RNV with high contrast at a safe laser energy of 80 nJ. SD-OCT was used to identify a cross-sectional structure of RNV. In addition, dynamic changes in the retinal morphology and retinal neovascularization were observed at day 4, 5, 6, 7, 9, 11, 14, 28, and day 35 after VEGF injection. PAM demonstrated high-resolution optical absorption of hemoglobin and vascular imaging of the retina and choroid with increased depth of penetration. With the current multimodal imaging system, RNV can be easily visualized in both 2D and 3D angiography. This multimodal ocular imaging system provides improved characterization of the microvasculature in a safe manner in larger rabbit eyes.
关键词： PAM,VEGF,multimodal imaging,optical coherence tomography,photoacoustic microscopy,retinal neovascularization,vascular endothelial growth factor,OCT
更新于2025-09-23 15:22:29
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Growth, optical, mechanical and nonlinear optical properties of Furfurylaminium 2-chloro-5-nitrobenzoate single crystal
摘要： The furfurylaminium 2-chloro-5-nitrobenzoate (FC) is a modernized organic material possessing enhanced order three nonlinearity. The crystals of FC of dimensions 17 × 4 × 2 mm3 were yielded on slow evaporation with the usage of ethanol-water mixed solvent (1:1). The precise peaks in powder XRD analysis reveal the crystalline property of the compound. The lattice parameters was estimated (a = 11.77 ± 0.012 ?, b = 6.84 ± 0.012 ? and c = 16.33 ± 0.028 ? and volume = 1342 ?3) from powder XRD using XRDA software. The FC crystal corresponds to the system of monoclinic with the space group P21/c. The UV-visible spectrum of FC crystal sample furnishes the lower cut off wavelength (325 nm) and the band gap (3.57 eV) for FC crystal. The dispersion factors Eo and Ed was calculated to be 4.24 eV and 15.20 eV respectively from Wemple and Di Domenico single oscillator model. Using these values, the oscillator strength value was calculated to be 64.5134 (eV) 2 and the moments of optical spectra was estimated to be M -1 = 3.580 (eV) 2 and M -3= 0.198 (eV) 2. The optical conductivity (σ) value of FC crystal at 532 nm was found out to be 0.21 ×1010 s-1. A red emission peak at 691 nm was obtained in photoluminescence spectra when the FC sample was excited at 325 nm. Single shot LDT value for FC crystal was calculated to be 14.40 GW/ cm2. The third order optical susceptibility (χ(3)) of the molecule was enumerated as 4.02 ×10-6 esu from Z-scan technique and the second order hyperpolarizability (γ) value is calculated to be 2.64 × 10-35 esu. The coupling factor (ρ*) is estimated to be 0.047, on utilizing the calculated values of (Re χ(3) = 0.19 × 10-6 esu) and (Im χ(3) =0.19 × 10-6 esu) from Z scan technique. The specific heat capacity (Cp) at 50°C was calculated as 1.5810 (Jg-1 K-1) and thermal diffusivity (α) as 1.750 ×10-6 m2/s. Thus using α the thermo-optic coefficient was deliberated to be 5.34 × 10-6 K-1. The maximum output power of FC indicates its optical limiting behaviour.
关键词： third order susceptibility,optical limiting,Solution growth,Optical materials,Z-scan
更新于2025-09-23 15:22:29
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Identification of Wheat Yellow Rust Using Optimal Three-Band Spectral Indices in Different Growth Stages
摘要： Yellow rust, a widely known destructive wheat disease, affects wheat quality and causes large economic losses in wheat production. Hyperspectral remote sensing has shown potential for the detection of plant disease. This study aimed to analyze the spectral reflectance of the wheat canopy in the range of 350–1000 nm and to develop optimal spectral indices to detect yellow rust disease in wheat at different growth stages. The sensitive wavebands of healthy and infected wheat were located in the range 460–720 nm in the early-mid growth stage (from booting to anthesis), and in the ranges 568–709 nm and 725–1000 nm in the mid-late growth stage (from filling to milky ripeness), respectively. All possible three-band combinations over these sensitive wavebands were calculated as the forms of PRI (Photochemical Reflectance Index) and ARI (Anthocyanin Reflectance Index) at different growth stages and assessed to determine whether they could be used for estimating the severity of yellow rust disease. The optimal spectral index for estimating wheat infected by yellow rust disease was PRI (570, 525, 705) during the early-mid growth stage with R2 of 0.669, and ARI (860, 790, 750) during the mid-late growth stage with R2 of 0.888. Comparison of the proposed spectral indices with previously reported vegetation indices were able to satisfactorily discriminate wheat yellow rust. The classification accuracy for PRI (570, 525, 705) was 80.6% and the kappa coefficient was 0.61 in early-mid growth stage, and the classification accuracy for ARI (860, 790, 750) was 91.9% and the kappa coefficient was 0.75 in mid-late growth stage. The classification accuracy of the two indices reached 84.1% and 93.2% in the early-mid and mid-late growth stages in the validated dataset, respectively. We conclude that the three-band spectral indices PRI (570, 525, 705) and ARI (860, 790, 750) are optimal for monitoring yellow rust infection in these two growth stages, respectively. Our method is expected to provide a technical basis for wheat disease detection and prevention in the early-mid growth stage, and the estimation of yield losses in the mid-late growth stage.
关键词： yellow rust disease,three-band spectral index,different growth stages,hyperspectral remote sensing,wheat infection
更新于2025-09-23 15:22:29
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Enlargement of Gold Nanoparticles for Sensitive Immunochromatographic Diagnostics of Potato Brown Rot
摘要： Lateral ?ow immunoassay (LFIA) is a convenient tool for rapid ?eld-based control of various bacterial targets. However, for many applications, the detection limits obtained by LFIA are not suf?cient. In this paper, we propose enlarging gold nanoparticles’ (GNPs) size to develop a sensitive lateral ?ow immunoassay to detect Ralstonia solanacearum. This bacterium is a quarantine organism that causes potato brown rot. We fabricated lateral ?ow test strips using gold nanoparticles (17.4 ± 1.0 nm) as a label and their conjugates with antibodies speci?c to R. solanacearum. We proposed a signal enhancement in the test strips’ test zone due to the tetrachloroauric (III) anion reduction on the GNP surface, and the increase in size of the gold nanoparticles on the test strips was approximately up to 100 nm, as con?rmed by scanning electron microscopy. Overall, the gold enhancement approach decreased the detection limit of R. solanacearum by 33 times, to as low as 3 × 104 cells·mL–1 in the potato tuber extract. The achieved detection limit allows the diagnosis of latent infection in potato tubers. The developed approach based on gold enhancement does not complicate analyses and requires only 3 min. The developed assay together with the sample preparation and gold enlargement requires 15 min. Thus, the developed approach is promising for the development of lateral ?ow test strips and their subsequent introduction into diagnostic practice.
关键词： gold nanoparticles,immunochromatographic diagnostics,potato brown rot,gold particle growth,increase of sensitivity,lateral ?ow immunoassay,test strips,Ralstonia solanacearum
更新于2025-09-23 15:22:29
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Compact Solid State Neutron-Gamma Detectors for Backpack or Handheld Instruments
摘要： In this paper, we report on the characterization of detectors constructed at RMD using 1-inch, 1.5-inch, and 2-inch diameter right cylinders of CLYC and CLLBC crystals coupled to arrays of silicon photomultipliers (SiPM). Detectors constructed with small volume CLLBC crystals coupled to a 12 mm × 12mm total area SiPM array show an excellent energy resolution of ~3% at 662 keV and a large volume CLYC crystal when coupled to a 24 mm × 24 mm area array shows an energy resolution of ~6.6% at 662 keV. Both detectors show pulse shape discrimination capabilities.
关键词： Gamma-ray detection,crystal growth,elpasolites,energy resolution,neutron detection,scintillation detector,CLLBC,CLYC,thermal neutrons
更新于2025-09-23 15:22:29
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An Electrical Analysis of a Metal-Interlayer-Semiconductor Structure on High-Quality Si <sub/> 1? <i>x</i> </sub> Ge <sub/><i>x</i> </sub> Films for Non-Alloyed Ohmic Contact
摘要： In this paper, we have investigated the effect of a metal-interlayer-semiconductor (MIS) structure on intrinsic silicon-germanium (SiGe) film which is epitaxially grown by ultra-high vacuum chemical vapor deposition (UHV-CVD). Ultra-thin dielectric materials can alleviate Fermi-level pinning at the metal/Si1?xGex contact region by preventing penetration into the Si1?xGex of metal-induced gap states (MIGS) from the metal surface. The electrical properties which are the back-to-back current density and specific contact resistivity of the Ti/TiO2/Si1?xGex structure improve at the TiO2 interlayer thickness of 0.5 nm for all kinds of Si1?xGex film with various levels of germanium (Ge) concentration. The case of Si0.7Ge0.3 film, the specific contact resistivity of a Ti/TiO2(0.5 nm)/Si0.7Ge0.3 structure is reduced 80-fold compared to that of a Ti/Si0.7Ge0.3 structure. The effect of the MIS structure has been well demonstrated on Si1?xGex film, and as a result this structure is suggested as a novel source/drain (S/D) contact scheme for advanced Si1?xGex complementary metal-oxide-semiconductor (CMOS) technology.
关键词： Epitaxial Growth,Metal-Interlayer-Semiconductor,Source/Drain Contact,Silicon-Germanium,Fermi-Level Pinning,Specific Contact Resistivity
更新于2025-09-23 15:22:29
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Chitosan-based hydrogels prepared by UV polymerization for wound dressing
摘要： Chitosan-based hydrogels were prepared by grafting with poly(acrylic acid) (PAA) and poly(hydroxyethyl methacrylate) (pHEMA) through ultraviolet polymerization to further improve its hydrophilic nature and enhance its mechanical properties. The epidermal growth factor (EGF) was incorporated inside the hydrogels to stimulate the wound healing. The physical characterization of chitosan-PAA-pHEMA hydrogel indicates that it is highly hydrophilic with adequate properties for wound dressing purpose. The biological characterization shows that chitosan-based hydrogel retains its thrombogenic and antibacterial properties. The in vivo wound healing experiment demonstrates that the hydrogel-incorporated EGF has better wound healing rate than other dressings.
关键词： hydrogel,Chitosan,2-hydroxyethyl methacrylate,epidermal growth factor,wound dressing,acrylic acid
更新于2025-09-23 15:22:29
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Formation of Growth-Mediated Gold Nanoflowers: Roles of the Reducing Agent and Amine-Modified, Single-Strand DNA Sequences
摘要： The formation of growth-mediated structures from gold nanoparticle seeds was studied in the presence of amine-modified single-strand DNA sequences and reducing agents such as hydroxylamine and hydroquinone. In the case of hydroxylamine, gold nanoparticle seeds (0.45 nM) were incubated with amine-modified single-strand DNA probes PMR (amine-5’-ACATCAGT-3’) and PML (amine-5’-GATAAGCT-3’), which resulted in gold nanoflowers and nanospheres, respectively. When the concentration of the nanoparticle seeds was varied (0.15–0.45 nM), only the PMR sequence showed growth-mediated development of gold nanoflowers. The size of the gold nanoparticles obtained is independent of the seed concentration for both PMR and PML sequences. In contrast, in the presence of the reducing agent hydroquinone, the growth processes are identical for both the sequences. At a lower seed concentration (0.15 nM), gold nanoflowers of larger size were observed for both sequences, whereas at higher seed concentrations (0.45 nM), much smaller gold nanospheres resulted. The formation and stability of nanoflowers and nanospheres for PMR and PML with hydroxylamine-based reduction were further studied in detail with diverse controlled amine-modified (5’-, 3’- and both end-modified) and non-modified DNA sequences with other mutants of these two sequences.
关键词： DNA structures,gold nanoparticles,reducing agents,growth factors,nanoflowers
更新于2025-09-23 15:22:29
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Chiral semiconductor nanorod heterostructures with high photocatalysis activity
摘要： Chiral semiconductor nanorods and their heterostructures have attracted intense attention. In this work, it was shown that chiral amino acids on CdSe@CdS semiconductor nanorods (SNR) displayed circular dichroism bands (CD, 200–480 nm). Longer SNRs were found to induce stronger CD intensities, while an increase in the SNR diameter led to a clear CD band redshift. Multi-site post-growth of platinum (Pt) and gold (Au) further enhanced the CD intensity and induced CD band transitions. Electromagnetic calculations revealed that the metal post-growth gave rise to a strong electromagnetic field enhancement, with Pt inducing a stronger enhancement than Au. The optimized chiral multi-sites platinum on SNR displayed higher photocatalytic activities manifested that the deposited metal endowed energy transfer and enhanced the separation of photo-excited electrons and holes. These findings demonstrated that the multi-sites deposited metal provided a method to produce strong optical activity of nanostructures by adjusting the morphology of the semiconductor nanorod.
关键词： circular dichroism,metal growth,heterostructure,semiconductor nanorods
更新于2025-09-23 15:22:29
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Extracellular vesicles based self-grown gold nanopopcorn for combinatorial chemo-photothermal therapy
摘要： Here, we generated a popcorn-like gold nanostructure exploiting extracellular vesicles (EVs). EVs can first serve as the vehicle for chemotherapeutic drug doxorubicin (DOX). Taking advantages of EVs, gold nanoparticles can be then self-grown surrounding the EVs, assembling into popcorn-like nanostructure. The formulated nanopopcorn, consisting of self-grown gold nanoparticles and EVs encapsulated with DOX, retained the photothermal transduction from gold nanoparticle assemblies and cytotoxicity of DOX. Under external near infrared irradiation, gold nanopopcorn can produce hyperthermia to induce tumor ablation and trigger drug release, achieving combinatorial chemo-photothermal therapy. The nanoplatform demonstrated improved cellular internalization, controlled drug release, enhanced antitumor efficacy with tumor inhibitory rate up to 98.6% and reduced side effects. Our design of popcorn-like nanostructure will contribute a novel modality for facile and green synthesis of complex metal nanostructures exploiting natural properties of EVs for combinational therapy.
关键词： photothermal therapy,self-growth,gold nanopopcorn,chemotherapy,extracellular vesicles
更新于2025-09-23 15:22:29