Diffusion deposition of aerosol nanoparticles in model granular filters

The diffusion deposition of point aerosol particles from a flow in model granular (grained) filters, i.e., separate layers composed of parallel chains of spherical granules, has been studied at small Reynolds numbers. Numerical solution of the Stokes and convective diffusion equations has been employed to determine the drag forces and granule collection efficiencies as depending on the Peclet diffusion number in a range Pe = 0.02–2 × 10⁴ and the ratio between the granule diameter and the distance between chain axes. Layers of closed chains with square and hexagonal packings have been considered. Approximation formulas have been derived for calculation of nanoparticle penetration in model granular filters.     

Comprehensive Examination of Mechanical and Diffusional Effects on Cell Behavior Using a Decoupled 3D Hydrogel System

Hydrogels possess several physical and chemical properties suitable for engineering cellular environments for biomedical applications. Despite recent advances in hydrogel systems for cell culture, it is still a significant challenge to independently control the mechanical and diffusional properties of hydrogels, both of which are well known to influence various cell behaviors when using hydrogels as 3D cell culture systems. Controlling the crosslinking density of a hydrogel system to tune the mechanical properties inevitably affects their diffusional properties, as the crosslinking density and diffusion are often inversely correlated. In this study, a polymeric crosslinker is demonstrated that allows for the adjustment of the degree of substitution of reactive functional groups. By using this polymeric crosslinker, the rigidity of the resulting hydrogel is controlled in a wide range without changing the polymer concentration. Furthermore, their diffusional properties, as characterized by their swelling ratios, pore diameters, and drug release rates, are not significantly affected by the changes in the degree of substitution. 3D cell studies using this hydrogel system successfully demonstrate the varying effects of mechanical properties on different cell types, whereas those in a conventional hydrogel system are more significantly influenced by changes in diffusional properties.     

Surfactantless photochemical deposition of gold nanoparticles on an optical fiber core for surface-enhanced Raman scattering

Surface-enhanced Raman scattering (SERS) probes based on gold nanoparticles modifying the core of the optical fiber were made by a surfactantless photochemical deposition method. The growth kinetics and shape evolution of gold nanoparticles depending on different experimental conditions were studied. It was found that, under the condition of detectable gold nanoparticle deposition, increasing the concentration of chloroauric acid (HAuCl(4)) was not conducive to the deposition whereas increasing the concentration of sodium citrate (Na(3)Ct) would speed up the deposition. By controlling the concentration of the reaction solution and irradiation time, we obtained fused spherical-like, spherical, and flowerlike gold nanoparticles. To test the SERS activity of the probes, the SERS spectra of a rhodamine 6G aqueous solution were recorded in direct detection mode and remote mode. We have also developed a new approach to improving the SERS sensitivity when detecting in remote mode.     

Stokes flow and deposition of aerosol nanoparticles in model filters composed of elliptic fibers

The calculation is implemented for the fiber collection efficiencies due to diffusion of nanoparticles in model filters, i.e., separate rows of fibers with an elliptic cross section located normal to the flow at different orientations of the ellipse axes with respect to the flow. The Stokes flow field in the system of the fibers is found by the method of fundamental solutions. The concentration field of Brownian particles and the efficiency of their deposition onto the fibers are determined from the numerical solution of the equation for the convective diffusion. The dependence of the capture coefficient on the Peclet number for elliptic fibers is shown to have the form η = APe^−m, where exponent m changes from 2/3 to 3/4 at the parallel and normal orientation of the major axes of the ellipses with respect to the flow, respectively. It is shown that, from the viewpoint of aerosol nanoparticle capture, the best filters are those in which the fibers have a maximum midsection at the same cross-sectional area.     

Synthesis and electrophoretic deposition of high-dielectric-constant SrTiO3 nanoparticles

We have investigated on the synthesis of SrTiO₃ nanoparticles whose bulk exhibits dielectric constant of 300, and their colloidal dispersion. As a result, we successfully synthesized SrTiO₃ nanoparticles with an average diameter of 134–485 nm measured by a scanning electron microscopic observation. The SrTiO₃ nanoparticles with a negative charge (ζ = −25 to −31 mV) can be dispersed as colloidal nanoparticles in water, and the average diameter in the dispersion were 138–356 nm measured by a dynamic light scattering technique. The colloidal dispersion of SrTiO₃ nanoparticles is promising for fabrication of low-voltage organic field-effect transistors (FETs) by a wet-processing fabrication. We have also successfully prepared SrTiO₃ films with a thickness of 1–10 μm on n-doped silicon substrates by an electrophoretic deposition technique. The SrTiO₃ films on the silicon substrates are likely used as dielectric gate insulator to low-voltage organic FETs after a sintering treatment.     

Selective deposition of polystyrene nanoparticles in a nanoetchpit array on a silicon substrate

Nanometer-sized polystyrene particles were selectively deposited by interfacial tension in nanometer-sized etchpit arrays made on a silicon substrate.     

长纤维高速过滤器性能优势分析

通过对净水厂沉淀出水和长江源水的过滤试验并与传统砂滤池及已在实际过程中推广应用的二类纤维过滤器进行了对比分析表明,本组研制的长纤维高速过滤器具有结构和性能上的明显优势。     

Post-synthesis deposition of V-zeolitic nanoparticles in SBA-15

A post-synthesis deposition of vanadium silicalite-1 zeolite nanoparticles in the pores of SBA-15 results in a highly ordered hexagonal templated silica material with V-silicalite zeolitic plugs, giving rise to an increased crystallinity of the amorphous mesoporous walls.     

Fracture resistance measurement of fused deposition modeling 3D printed polymers

A method is presented to characterize the fracture resistance and interlayer adhesion of fused deposition modeling (FDM) 3D printed materials. Double cantilever beam (DCB) specimens of acrylonitrile butadiene styrene (ABS) were designed and printed with a precrack at the layers' interface. The DCBs were loaded in an opening mode and the load-displacement curves were synchronized with the optical visualization of the crack tip to detect the critical load at the crack initiation. A finite element model, coupled with J-integral method and fracture surface analysis was then developed to obtain the apparent fracture resistance (J_cr,a) and the interlayer fracture resistance (J_cr,i), as a measure of the interlayer adhesion. The maximum J_cr,i was measured to be 4017 J/m², a value close to the fracture resistance of bulk ABS. Both J_cr,a and J_cr,i increased with the printing temperature. This method can find a great importance in the structural applications of printed materials.     

Development of a method for nuclide leaching from glass fiber in HEPA filter

For the disposal of the high efficiency particulate air (HEPA) glass filter to environment, the glass fiber should be leached to lower its radioactive concentration. To derive the optimum method for removal of Co and Cs from HEPA glass fiber, four methods were applied in this study. Results of electrochemical leaching of glass fiber by 4.0 M HNO₃–0.1 M Ce(IV) solution showed that the removal efficiency of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs from glass fiber after 5 h was 96.4, 93.6, and 93.8%, respectively. Results by 5 wt% NaOH solution showed that the removal efficiency of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 30 h was 81.7, 82.1, and 10.0%, respectively. Results by repeat 2.0 M HNO₃ solution showed that the removal efficiencies of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 2 h of three repetitions were 96.2, 99.4, and 99.1%, respectively. Finally, results by repeat 4.0 M HNO₃ solution showed that the removal efficiencies of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 4 h of three repetitions were 100, 99.9, and 99.9%, respectively, and their radioactivities were below 0.1 Bq/g. Therefore, the chemical leaching method by 4.0 M HNO₃ solution was considered as an optimum one for removal of cesium and cobalt from HEPA glass fiber for self disposal. Also the removal efficiencies of ⁶⁰Co, ¹³⁴Cs, and ¹³⁷Cs from the waste-solution after its precipitation-filtration treatment for reuse of 4.0 M HNO₃ waste-solution were 88.0, 95.0, and 99.8%.     

Use of inorganic fiber filter paper in gravimetric microanalysis

Summary Filter mats for filtersticks, filter tubes, andGooch crucibles are easily prepared with the use of filter papers made of glass fibers or fibers of vitreous silica. The reliability of such filter mats for the purpose of quantitative micro analysis has been tested with silica fiber paper which is somewhat more difficult to use, but permits high ignition temperatures.

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Zusammenfassung Filterstäbchen, Filterröhrchen undGooch-Tiegel können in einfacher Weise mit beständigen Filterschichten aus anorganischem Filtrierpapier, das aus feinen Glasoder Quarzfäden hergestellt ist, versehen werden. Die Eignung solcher Filterschichten für Zwecke der quantitativen Mikroanalyse erscheint durch Versuche mit Quarzfaserpapier erwiesen, das schwieriger zu handhaben ist als Glasfaserpapiere, dafür aber hohe Glühtemperaturen zuläßt.

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Résumé On prépare aisément avec de la soie de verre ou de la silice vitreuse des plaquettes filtrantes pour baguettes, tubes et creusets de Gooch. De telles plaquettes ont été soumises à l'épreuve pour la micro-analyse quantitative avec de la laine de silice qui est un peu plus difficile à employer mais permet des températures d'ignition plus élevées.

     

Anticancer therapeutic efficacy of biogenic Am-ZnO nanoparticles on 2D and 3D tumor models

The present study fabricates biogenic zinc oxide nanoparticles (ZnO NPs) with the aqueous leaf extract of Annona muricata (Am) plant collected from semi-evergreen forests of Odisha, India. The synthesized Am-ZnO NPs were physicochemically characterized. The ultraviolet/visible spectrum showed the maximum optical absorbance of Am-ZnO NPs at 355 nm. High-resolution transmission electron microscopy analysis presented the nearly spherical shape of Am-ZnO NPs with an average particle size of 80 nm. The net surface charge and hydrodynamic size of Am-ZnO NPs were measured to be ～?2.59 mV and ～417 nm, respectively. Am-ZnO NPs were found to be biocompatible and hemocompatible nature. Furthermore, Am-ZnO NPs displayed strong anticancer effects on both 2D and 3D tumor models. We observed a dose-dependent toxicity on both A549 and MOLT4 cells and observed a size reduction in the A549 tumor spheroids. Subsequently, we observed a depolarization in mitochondrial membrane potential of Am-ZnO NP–treated cancer cells leading to the apoptosis induction in cancer cells.     

Controlled synthesis of self-assembled 3D nanostructures using metastable atomic layer deposition

An important feature of atomic layer deposition (ALD) is the fact that the coating that has been deposited is conformal to the substrate surface. Therefore, prepatterned substrates are usually used for the fabrication of 3D nanostructures using ALD. This article presents a new method to generate 3D silver-silica nanostructures using plasma-enhanced atomic layer deposition of silica with tri(dimethylamino)silane (TDMAS) and oxygen plasma as precursors. For this method, silver nanoparticles are used as templates, and during the deposition of silica, the repeatable process of the formation of metastable silver oxides and their decomposition is involved, leading to strong side reactions and the formation of 3D silver-silica hybrid nanostructures. This method is known as metastable atomic layer deposition (MS-ALD). Unlike the conventional ALD, the coating of MS-ALD is not conformal to the substrate surface. Rather, the 3D nanostructures are self-assembled because of side reactions. The geometry of the formed nanostructures can be easily adjusted by tuning the deposition parameters, such as dose time of both precursors and cycle numbers. In our study, we observed nanosponges with features sizes of up to 4 for less than 45 MS-ALD cycles. Nanowire-like silver-silica hybrid nanostructures are generated at higher cycle numbers with feature sizes of up to 10 μm. A similar trend could be observed for changing the dose time of both precursors of TDMAS and oxygen plasma. The height of the nanostructures increases with dose time of both precursors. In contrast to this trend, the surface coverage declines when the investigated parameters (number of cycles, TDMAS, and oxygen plasma dose time) are increased.     

Single-step synthesis of gold-silver alloy nanoparticles in ionic liquids by a sputter deposition technique

The simultaneous sputter deposition of gold and silver onto ionic liquids formed bimetallic alloy nanoparticles, which exhibited composition-sensitive surface plasmon resonance, the peak wavelength being red-shifted with an increase in the surface area of the gold foil targets sputtered.     

Colloidal deposition synthesis of supported gold nanocatalysts based on Au-Fe3O4 dumbbell nanoparticles

Highly active Au catalysts with a dumbbell-like heterostructure for CO oxidation were prepared through colloidal deposition method; both activities and stabilities were investigated under different experimental conditions.     

Controlled deposition of nanoparticles at the liquid-liquid interface

We report a novel method for the preparation of well-defined metallic nanoparticles, which is illustrated with the technologically important example of palladium nanoparticles dispersed in gamma-alumina.     

Antibacterial thermoplastic polyurethane electrospun fiber mats prepared by 3-aminopropyltriethoxysilane-assisted adsorption of Ag nanoparticles

Antibacterial thermoplastic polyurethane(TPU) electrospun fiber mats were prepared by adsorption of Ag nanoparticles(Ag NPs) onto TPU/3-aminopropyltriethoxysilane(APS) co-electrospun fiber mats from silver sol. The use of APS can functionalize TPU fibers with amino groups, facilitating the adsorption of Ag NPs. The effects of p H of silver sol and APS content on Ag NP adsorption and antibacterial activity were investigated. Ag NP adsorption was evidenced by TEM, XPS and TGA. Significant Ag NP adsorption occurred at p H = 3-5. The main driving force for Ag NP adsorption is electrostatic interaction between ―NH3~+ of the fibers and ―COO-derived from the ―COOH group capped on the surfaces of Ag NPs. The antibacterial activity of the Ag NP-decorated TPU/APS fiber mats was investigated using both gram-negative Escherichia coli and gram-positive Bacillus subtilis. The antibacterial rate increases with increasing APS content up to 5% where the antibacterial rates against both types of bacteria are over 99.9%.