Control of Radiative Properties of Coatings Pigmented With Fe2O3 Nanoparticles

2011 ◽  
Author(s):  
Hiroki Gonome ◽  
Mehdi Baneshi ◽  
Atsuki Komiya ◽  
Shigenao Maruyama
Keyword(s):  
Near Infrared ◽  
Average Particle Size ◽  
Optimization Method ◽  
Radiative Properties ◽  
Average Particle ◽  
Emission Model ◽  
Properties Of Coatings ◽  
Spectral Behavior ◽  
Pigmented Coatings ◽  
Numerical Approaches

This study describes nanoparticles pigmented coatings used in controlling the radiative properties of surfaces exposed to sunlight. An optimization method that embraces both thermal and aesthetic requirements has been proposed. The proposed coatings maximize the reflectivity of the near infrared (NIR) region to reduce thermal heating, while for aesthetic appeal they minimize the visible (VIS) reflected energy. This spectral behavior can be achieved by controlling the size and concentration of pigment particles and coating thickness. In this study, both experimental and numerical approaches are applied on Fe2O3 pigmented coating samples with 0.2 μm and 1 μm of average particle size and different particle concentrations and coating thicknesses. For numerical part the radiation analysis using the Radiation Element Method by Ray Emission Model (REM2) in a one dimensional parallel plane model is conducted. From the numerical results, it is shown that the optimum size of Fe2O3 particles for our desired spectral behavior is about 0.8 μm. The experimental results also show that the samples made from 1 μm particles have better performance for our objective.

Near Infrared Tunable Gold Nanoparticles for Low Power Laser Ablation of Esophageal Adenocarcinoma

2012 ◽  
Vol 1416 ◽  
Author(s):  
Guandong Zhang ◽  
Jacek Jasinski ◽  
Dhruvinkumar Patel ◽  
Kurtis James ◽  
Xinghua Sun ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Low Power ◽  
Esophageal Adenocarcinoma ◽  
Near Infrared ◽  
Average Particle Size ◽  
Sodium Thiosulfate ◽  
Molar Ratio ◽  
Average Particle ◽  
Chloroauric Acid ◽  
Nir Absorption

ABSTRACTGold nanoparticles (GNPs) with precisely controlled near infrared (NIR) absorption were synthesized by one-step reaction of chloroauric acid and sodium thiosulfate. The NIR absorption wavelengths and average particle size increase with increasing molar ratio of HAuCl4/Na2S2O3. The as-synthesized GNPs consist of different shape and size, including small spherical gold colloids and larger non-spherical gold crystals. The GNPs with good chemical and optical stability only form in a suitable range of the HAuCl4/Na2S2O3 molar ratio. High molar ratio of HAuCl4/Na2S2O3 reduces GNPs stability due to Ostwald ripening. Chitosan coating improves particle stability and allows these GNPs effective ablation for esophageal adenocarcinoma under low power NIR laser radiation.

scholarly journals Cascade Release Nanocarriers for the Triple-Negative Breast Cancer Near-Infrared Imaging and Photothermal-Chemo Synergistic Therapy

2021 ◽  
Vol 11 ◽  
Author(s):  
Ke Li ◽  
Ruyue Li ◽  
Baona Zhou ◽  
Jing Chen ◽  
Kai Lan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Near Infrared ◽  
Triple Negative ◽  
Infrared Imaging ◽  
Average Particle Size ◽  
Average Particle ◽  
Near Infrared Imaging ◽  
Synchronous Tumor ◽  
Treatment Approaches

Triple-negative breast cancer (TNBC) has inadequate treatment approaches and a poor prognosis. It is urgent to develop new treatment approaches for TNBC. The combination of photothermal therapy (PTT) and chemotherapy is a very effective potential therapy for TNBC. However, asynchronous accumulation, unclear efficacy, and toxic side effects hinder the further promotion of this method. Therefore, we designed and constructed a new type of nanocarriers, the cascade release near-infrared imaging (NIFI) & thermal-chemo combination nanoparticles (CNC NPs), that can release drugs through the cascade of ultrasound triggering and pH responding to achieve the synchronous tumor accumulation, monitoring and synergistic treatment of two functional molecules. The key material of CNC NPs is the polydopamine (PDA), which, through self-assembling, forms a rigid shell that contains doxorubicin (DOX) and NIF fluorescent dye IR780 on the surface of the perfluorohexane (PFH) microbubbles. The results show that CNC NPs have a hollow core-shell structure with an average particle size of 97.3 ± 27.2 nm and have exceptional colloidal stability and photothermal conversion efficiency. The NPs can effectively perform cascade drug release through ultrasound triggering and pH responding. CNC NPs have good in vivo biological safety and excellent fluorescence imaging, drug delivery, and therapeutic abilities in the TNBC models. These results provide an experimental basis for the development of new clinical treatment methods for TNBC.

Infrared Radiative Properties of Thin Polyethylene Coating Pigmented With Titanium Dioxide Particles

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Mehdi Baneshi ◽  
Shigenao Maruyama ◽  
Atsuki Komiya
Keyword(s):  
Particle Size ◽  
Volume Fraction ◽  
Near Field ◽  
Field Approximation ◽  
Anisotropic Scattering ◽  
Radiative Properties ◽  
Emission Model ◽  
Tio2 Pigment ◽  
Pigmented Coatings ◽  
Thin Polyethylene

The infrared (IR) radiative properties of TiO2 pigment particles must be known to perform thermal analysis of a TiO2 pigmented coating. Resins generally used in making pigmented coatings are absorbing at IR wavelengths, which means that the conventional Mie solution (MS) may not be adequate in this domain. There are two approaches to evaluating radiative properties in an absorbing medium: far field approximation (FFA) and near field approximation (NFA). In this study, after reviewing these two approaches, we evaluated the radiative properties of TiO2 particles in polyethylene resin as an absorbing matrix in the wavelength range of 1.7–15 μm based on the MS, FFA, and NFA. We then calculated the effective scattering and absorption coefficients for different models. To investigate the effect of the particle size and volume concentration on the transmittance of IR wavelengths, we made a nongray radiative heat transfer in an anisotropic scattering monodisperse pigmented layer, with independent scattering using the radiation element method by the ray emission model. The results showed that all three approaches predicted similar results in the particle size domain and volume fraction range utilized in pigmented coatings.

scholarly journals An Injectable Click-Crosslinked Hydrogel that Prolongs Dexamethasone Release from Dexamethasone-Loaded Microspheres

Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 438 ◽  
Author(s):  
Ji Yeon Heo ◽  
Jung Hyun Noh ◽  
Seung Hun Park ◽  
Yun Bae Ji ◽  
Hyeon Jin Ju ◽  
...  
Keyword(s):  
Near Infrared ◽  
Click Reaction ◽  
Subcutaneous Tissue ◽  
Average Particle Size ◽  
Average Particle ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Near Infrared Fluorescence Imaging

Our purpose was to test whether a preparation of injectable formulations of dexamethasone (Dex)-loaded microspheres (Dex-Ms) mixed with click-crosslinked hyaluronic acid (Cx-HA) (or Pluronic (PH) for comparison) prolongs therapeutic levels of released Dex. Dex-Ms were prepared using a monoaxial-nozzle ultrasonic atomizer with an 85% yield of the Dex-Ms preparation, encapsulation efficiency of 80%, and average particle size of 57 μm. Cx-HA was prepared via a click reaction between transcyclooctene (TCO)-modified HA (TCO-HA) and tetrazine (TET)-modified HA (TET-HA). The injectable formulations (Dex-Ms/PH and Dex-Ms/Cx-HA) were fabricated as suspensions and became a Dex-Ms-loaded hydrogel drug depot after injection into the subcutaneous tissue of Sprague Dawley rats. Dex-Ms alone also formed a drug depot after injection. The Cx-HA hydrogel persisted in vivo for 28 days, but the PH hydrogel disappeared within six days, as evidenced by in vivo near-infrared fluorescence imaging. The in vitro and in vivo cumulative release of Dex by Dex-Ms/Cx-HA was much slower in the early days, followed by sustained release for 28 days, compared with Dex-Ms alone and Dex-Ms/PH. The reason was that the Cx-HA hydrogel acted as an external gel matrix for Dex-Ms, resulting in the retarded release of Dex from Dex-Ms. Therefore, we achieved significantly extended duration of a Dex release from an in vivo Dex-Ms-loaded hydrogel drug depot formed by Dex-Ms wrapped in an injectable click-crosslinked HA hydrogel in a minimally invasive manner. In conclusion, the Dex-Ms/Cx-HA drug depot described in this work showed excellent performance on extended in vivo delivery of Dex.

Size Reduction and Rare Earth Doping of GaN Powders through Ball Milling

2009 ◽  
Vol 1202 ◽  
Author(s):  
Xiaomei Guo ◽  
Tiju Thomas ◽  
Kewen Kevin Li ◽  
Jifa Qi ◽  
Yangyun Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Ball Milling ◽  
Near Infrared ◽  
Average Particle Size ◽  
Ethanol Solution ◽  
Infrared Range ◽  
Rare Earth Doping ◽  
Average Particle ◽  
Heat Treated ◽  
Milled Powders

AbstractBall milling of ammonothermally synthesized GaN powders was performed in an ethanol solution for a variety of durations, resulting in average particle sizes of nanometer. The ball milled powders showed an obviously brightened color and improved dispersability, indicating reduced levels of aggregation. X-ray diffraction (XRD) peaks of the ball milled GaN powders were significantly broadened compared to those of the as-synthesized powders. The broadening of the XRD peaks was partially attributed to the reduction in the average particle size, which was confirmed through SEM analyses. On the other hand, rare earth doping of commercial GaN powders was also achieved through a ball mill assisted solid state reaction process. Rare earth salts were mixed with GaN powder by ball milling. The as-milled powders were heat treated under different conditions to facilitate the dopant diffusion. Luminescence properties of the rare earth doped GaN powders at near infrared range were investigated and the results were discussed.

Evaluation of Cerebral Hemodynamics and Tissue Morphology of In Vivo Rat Brain Using Spectral Diffuse Reflectance Imaging

2016 ◽  
Vol 71 (5) ◽  
pp. 866-878 ◽  
Author(s):  
Izumi Nishidate ◽  
Tomohiro Ishizuka ◽  
Afrina Mustari ◽  
Keiichiro Yoshida ◽  
Satoko Kawauchi ◽  
...  
Keyword(s):  
Particle Size ◽  
Brain Tissue ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Scattering Amplitude ◽  
Average Particle Size ◽  
Average Particle ◽  
Cortical Tissue ◽  
Deoxygenated Hemoglobin

We investigated a quantitative imaging of reduced scattering coefficients μs’( λ) and the absorption coefficients μa( λ) of in vivo cortical tissues in the range from visible to near-infrared (NIR) wavelengths based on diffuse reflectance spectral imaging technique. In this method, diffuse reflectance images of in vivo cortical tissue are acquired at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm). A multiple regression analysis aided by the Monte Carlo simulation for the absorbance spectra is then utilized to estimate the optical coefficients of cortical tissue. This analysis calculates the concentration of oxygenated hemoglobin and that of deoxygenated hemoglobin, the scattering amplitude a and the scattering power b. The spectrum of absorption coefficient is deduced from the estimated concentrations of oxygenated hemoglobin and deoxygenated hemoglobin. The spectrum of reduced scattering coefficient is determined by the estimated scattering amplitude and scattering power. The particle size distribution of microstructure is calculated from the estimated scattering power b for evaluating the morphological change in brain tissue quantitatively. Animal experiments with in vivo exposed brain of rats demonstrated that the responses of the absorption properties to hyperoxic and anoxic conditions are in agreement with the expected well-known cortical hemodynamics. The average particle size was significantly reduced immediately after the onset of anoxia and then it was changed into an increase, which implied the swelling and shrinkage of the cellular and subcellular structures induced by loss of tissue viability in brain tissue.

scholarly journals Preparation of Spherical Sub-Micron Alumina from Hainan Kaolin

CONVERTER ◽  
2021 ◽  
pp. 317-325
Author(s):  
Kai Xu, Jiafei Li, Yongming Zhang
Keyword(s):  
Particle Size ◽  
Uniform Design ◽  
Average Particle Size ◽  
Acid Leaching ◽  
Optimization Method ◽  
Source Material ◽  
Process Conditions ◽  
Alumina Powder ◽  
Average Particle ◽  
Uniform Dispersion

It is an effective way to prepare alumina by replacing bauxite with aluminous minerals. It was studied that the preparation of spherical sub-micron alumina from Hainan kaolin by alginate assisted dispersion. The results of the experiment showed that the alumina content in Hainan kaolin is more than 38%. The t process parameters as of extracting alumina by acid leaching were optimized by uniform design optimization method. The alumina extraction rate reached more than 97% with optimized process conditions. It was used as aluminum source material that he aluminum salt obtained from Hainan kaolin was treated with impurity removal. With this source material, and the purified alginate AG was used as dispersant，the α- Alumina powder with good sphericity, uniform dispersion and average particle size of about 350 was prepared.

Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽  
2020 ◽  
Vol 5 (57-58) ◽  
pp. 2961-2972
Author(s):  
P.C. Meléndez-González ◽  
E. Garza-Duran ◽  
J.C. Martínez-Loyola ◽  
P. Quintana-Owen ◽  
I.L. Alonso-Lemus ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Anion Exchange ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Carbon Spheres ◽  
Hollow Carbon ◽  
Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

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