Sanghoon Kim

pH-controlled delivery of curcumin from a compartmentalized solid lipid nanoparticle@mesostructured silica matrix

Silicalization of curcumin-loaded solid lipid nanoparticle (SLN)/micelle dispersions afforded a compartmentalized nanovector, with both macro- and mesostructured domains. SLNs act as reservoirs of curcumin (CU), while mesopores act as pathways to control drug release. Moreover, the release sustainability depends on the nature of the solid lipid (cetyl palmitate vs. stearic acid) and on the pH of the receiving phase. The meso-macrostructured silica matrix templated by SLNs appears thus as a promising drug delivery system for pH-responsive controlled release.

pH- and glutathione-responsive release of curcumin from mesoporous silica nanoparticles coated using tannic acid–Fe(III) complex

A novel pH- and glutathione-responsive drug delivery system has been developed by deposition of tannic acid (TA)–Fe(III) complex on the surface of mesoporous silica nanoparticles (MSN). The coating was easily accomplished within 30 seconds by successive addition of iron chloride (FeCl3) and tannic acid in aqueous dispersion of MSN (e.g. MCM-41). A hydrophobic model drug, curcumin, showed sustainable drug release under physiological condition (pH 7.4), while a rapid curcumin release was triggered by lowering the pH to 6.0 or 4.5. Moreover, curcumin release could be controlled by adjusting the glutathione level, which accelerate the decomposition of TA–Fe(III) complex by competitive liganding. Therefore, these results would allow developing novel and simple pH- and glutathione-responsive drug delivery systems with potential applications such as in biomedicine.

Core-shell microcapsules of solid lipid nanoparticles and mesoporous silica for enhanced oral delivery of curcumin.

Newly designed microcapsules (MC) combining a core of solid lipid nanoparticle (SLN) and a mesoporous silica shell have been developed and explored as oral delivery system of curcumin (CU). CU-loaded MC (MC-CU) are 2 μm sized and have a mesoporous silica shell of 0.3 μm thickness with a wormlike structure as characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption and transmission electron microscopy (TEM) measurements. It was found that SLN acts as reservoir of curcumin while the mesoporous shell insures the protection and the controlled release of the drug. MC-CU displayed a pH-dependent in vitro release profile with marked drug retention at pH 2.8. Neutral red uptake assay together with confocal laser scanning microscopy (CLSM) showed a good cell tolerance to MC-CU at relatively high concentration of inert materials. Besides, the cell-uptake test revealed that fluorescent-MC were well internalized into Caco-2 cells, confirming the possibility to use MC for gut cells targeting. These findings suggest that organic core-silica shell microcapsules are promising drug delivery systems with enhanced bioavailability for poorly soluble drugs.

Metallo-solid lipid nanoparticles as colloidal tools for meso-macroporous supported catalysts.

Meso-macroporous silica containing iron oxide nanoparticles (15-20 nm) was synthesized by formulating solid lipid nanoparticles and metallosurfactant as both template and metal source. Because of the high active surface area of the catalyst, the material exhibits an excellent performance in a Fenton-like reaction for methylene blue (MB) degradation, even at low amount of iron oxide (5% TOC after 14 h).

Nanoparticle-free magnetic mesoporous silica with magneto-responsive surfactants

Magneto-responsivity can be imprinted in hard mesoporous silica materials using soft colloidal templates formed by magnetic surfactants. The materials exhibit a low to high spin transition due to geometrical constraints of the isolated iron ions grafted on the silica walls.

Spin State As a Probe of Vesicle Self-Assembly.

A novel system of paramagnetic vesicles was designed using ion pairs of iron-containing surfactants. Unilamellar vesicles (diameter ≈ 200 nm) formed spontaneously and were characterized by cryogenic transmission electron microscopy, nanoparticle tracking analysis, and light and small-angle neutron scattering. Moreover, for the first time, it is shown that magnetization measurements can be used to investigate self-assembly of such functionalized systems, giving information on the vesicle compositions and distribution of surfactants between the bilayers and the aqueous bulk.

Sustainable polysaccharide-derived mesoporous carbons (Starbon®) as additives in lithium-ion batteries negative electrodes

For the first time, polysaccharide-derived mesoporous carbonaceous materials (Starbon®) are used as carbon additives in Li-ion battery negative electrodes. A set of samples with pore volumes ranging from ≈0 to 0.91 cm3 g−1 was prepared to evidence the role of porosity in such sustainable carbon additives. Both pore volume and pore diameter have been found crucial parameters for improving the electrodes performance e.g. reversible capacity. Mesoporous carbons with large pore volumes and pore diameters provide efficient pathways for both lithium ions and electrons as proven by the improved electrochemical performances of Li4Ti5O12 (LTO) and TiO2 based electrodes compared to conventional carbon additives. The mesopores provide easy access for the electrolyte to the active material surface, and the fibrous morphology favors the connection of active materials particles. These results suggest that polysaccharide-derived mesoporous carbonaceous materials are promising, sustainable carbon additives for Li-ion batteries.

Manage Space for Construction Facilities on High-Rise Buildings

Poor usage of space at construction sites is one of the leading causes of decreased productivity in the construction industry; however, it is manageable, and some instances preventable. This study focuses on how to efficiently manage space for construction facilities on high-rise buildings in congested urban areas where space for facilities around the building footprint is not available. The construction facilities layout plan provides a logical order and priority for space planning decisions with reasonable costs. Genetic Algorithm (GA) modeling assumptions are made in order to properly allocate space for facilities that will result in lower computational costs and increased in productivity. Introduction Construction productivity is greatly influenced by the organization of the project site and the flow of equipment, labor, and materials through the site. The most important resource is space since materials should be stored so they are accessible when needed. Materials storage area should be selected carefully to avoid impacting construction operations, and materials procured by the general contractor should be inspected upon delivery to ensure that the correct items and quantities were delivered. However, like any resource, the amount of construction site space demanded by the various activities changes with the schedule of the work. Therefore, as the schedule evolves during the project, the site layout may need to be efficiently re-organized at various intervals to satisfy the upcoming schedule requirements to maintain construction site productivity (Emad et al. 2001). Problem Statement Space and time conflicts have been identified as one of the major causes of productivity loss in construction [Ahuja and Nandakumar (1984); Kuntz (1994); Oglesby, Parker et al. (1989); Rad (1980); and Sanders, Thomas et al. (1989)]. Sanders, Thomas et al. (1989) stated that efficiency losses of up to 65% are due to congested workspace and up to 58% are due to restricted access. Howell et al. (1993) reported the elimination of sharing resources, such as work areas, as a first step for performance improvement at construction sites, especially when a site is very tight or Copyright ASCE 2004 Construction Research 2003 2 highly constrained such as construction in an urban environment or facility rehabilitation. This paper presents a facility layout model for multiple floor buildings in high-density urban areas. Related Research The most common study in space management in the industry is through site planning. These plans are necessary to manage not only space on the site for material deliveries, staging areas, and crane locations, but also space in high-rise buildings that are normally situated in congested urban locations. The results from literature over the last decade can be classified into two broad area of study: (1) space-scheduling [Riley (1994); and Thabet and Beliveau (1997)]:and (2) site layout planning [Tommelein and Zouein (1993); Tommelein, Levitt et al. (1991); Yeh (1995); Lin and Haas (1996); Philip, Mahadevan et al. (1997); Gero and Kazakov (1997); Li and Love (2000); Zouein and Tommelein (2001); Tam, Tong et al. (2002); and Zouein, Harmanani et al. (2002)]. However, this paper considers both space-scheduling and site layout planning which is shown in Figure 1. Figure 1. Facility layout planning approach Note: In construction, there are multiple meanings for the word facility. For the purposes of this paper, a facility is considered a direct or support resource to be used in construction. For example, a facility could be a material pile, tool cart, or porta-potty. Multiple-Floor Facility Layout Explore In most cases, the approach is to take the shortest path from one major activity to another. The objective of multiple-floor facility layout is to minimize the total cost of material handling. The formulation of objectives can be expressed as (1): facilities of number m activities of number n D W Min n

Alginic acid aquagel as a template and carbon source in the synthesis of Li4Ti5O12/C nanocomposites for application as anodes in Li-ion batteries

We report here a simple process for the synthesis of Li4Ti5O12(LTO)/carbon nanocomposites by a one-pot method using an alginic acid aquagel as a template and carbon source, and lithium acetate and TiO2 nanoparticles as precursors to the LTO phase. The carbon content can be tuned by adjusting the relative amount of alginic acid. The obtained materials consist of nanosized primary particles of LTO (30 nm) forming micron-sized aggregates covered by well-dispersed carbon (from 3 to 19 wt%). The homogeneous dispersion of carbon over the particles improves the electrochemical performance of LTO electrodes such as rate capability (>95 mA h g−1 at 40C) and cycling performance (>98% of retention after 500 cycles at 5C), even with only 3% of carbon black additive in the electrode formulation. With a simple and easily up-scalable synthesis, the LTO/carbon nanocomposites of this study are promising candidates as anode materials for practical application in lithium-ion batteries.