HepG2 Cell Resistance against Camptothecin from a Lysosomal Drug Delivery

A galactose‐appended drug delivery system released camptothecin (CPT) to lysosomes of HepG2 hepatoma cells, resulting in the cell resistance to the anticancer drug. We found that the resistance to CPT is caused by alteration of the drug release from the prodrug in lysosomes, emphasizing that the final delivery locations may critically influence drug efficacy.     

Positron annihilation lifetime spectroscopy of advanced reduced-activation alloy (ARAA) in cold‐worked conditions

Journal of Radioanalytical and Nuclear Chemistry - The defects due to cold-rolling deformation in the advanced reduced-activation alloy (ARAA) have been analyzed using positron annihilation...     

Controlled water flooding of polymer electrolyte fuel cells applying superhydrophobic gas diffusion layer

Water transport is critical to the successful implementation of polymer electrolyte fuel cells (PEFC), especially in long-term and dynamic operation in automotives. Liquid water appears in the fuel cells not only from the water generated at the cathode catalyst layer but also as a result of condensation of water vapor from the humidified gases. In this study, we report a simple approach to prepare a superhydrophobic gas diffusion layer by chemical vapor deposition of polydimethylsiloxane without significant change in pore size of gas diffusion layer unlike other approach adding hydrophobic agent such as polytetrafluoroethylene. A superhydrophobic coating on the GDL can be obtained, leading to exceptionally enhanced power performance and stability of PEFC especially at a high current where water transport becomes more critical.     

Ultraviolet photodissociation at 266 nm of phosphorylated peptide cations

Ultraviolet (UV) photodissociation (PD) experiments using 266 nm light were performed for a series of phosphopeptide cations in a Fourier transform mass spectrometer. The objective of the experiments was to determine whether 266 nm UV irradiation on the phosphopeptide cations would induce unique peptide backbone dissociation. In addition, the general behavior of the phosphate loss (?80 or ?98 Da) was monitored, particularly for those phosphopeptides with a phosphotyrosine residue that itself is a UV chromophore. For phosphopeptides with a UV chromophore, their photodissociation behavior was very similar to that of low‐energy sustained off‐resonance irradiation collisionally activated dissociation (SORI‐CAD), with a few exceptions. For example, b‐ and y‐type peptide backbone fragments were prevalent, and their dephosphorylation behavior was consistent with that of the SORI‐CAD results. For phosphoserine peptides, the loss of a phosphate group was always observed. On the other hand, for phosphotyrosine peptides, the phosphate loss was found to be dependent on the presence of a basic amino group in the sequence and the charge state of the precursor ions, in agreement with the CAD results in the literature. However, hydrogen atom loss or aromatic side chain loss, which is known to be the excited state specific fragmentation pathway, was rarely observed in our 266 nm UV PD experiments, in contrast to the previous UV PD literature (particularly at 220 nm). The mechanism for these observations is described in terms of dominant internal conversion followed by intramolecular vibrational energy redistribution (IVR). Copyright © 2009 John Wiley & Sons, Ltd.     

Analytical calculations and comparison with numerical data forannular klystrode

The performance of a klystrode is investigated for annular electron beams. Numerical simulations of the output cavity in the klystrode device are carried out by making use of the fully electromagnetic three-dimensional code, HFSS, and the fully electromagnetic, two-and-one-half-dimensional, self-consistent PIC code, MAGIC. In addition, an analytical expression to predict the efficiency and gap-field strength of the device is developed to investigate klystrode performance over a wide range of parameters. This analytical expression for the annular klystrode is developed based on the Maxwell's equations and Newton's second law of motion. The analytical results agree fairly well with data obtained numerically from the MAGIC code. The presented results indicate that the theoretical formula obtained from the analytical calculation may be useful for designing the klystrode microwave tubes     

A study of density in electron-cyclotron-resonance plasma

A theory is developed for the density profile of low temperature plasmas confined by applied magnetic field and an experiment of the electron-cyclotron-resonance (ECR) plasma is conducted to compare the theoretical prediction and experimental measurements. Due to a large electron mobility along the magnetic field, electrons move quickly out of the system, leaving ions behind and building a space charge potential, which leads to the ambipolar diffusion of ions. In a steady-state condition, the plasma generation by ionization of neutral molecules is in balance with plasma loss due to the diffusion, leading to the electron temperature equation, which is expressed in terms of the plasma size, chamber pressure, and the ionization energy and cross section of neutrals. The power balance condition leads to the plasma density equation, which is also expressed in terms of the electron temperature, the input microwave power and the chamber pressure. It is shown that the plasma density increases, reaches its peak and decreases, as the chamber pressure increases from a small value (0.1 mTorr). These simple expressions of electron temperature and density provide a scaling law of ECR plasma in terms of system parameters. After carrying out an experimental observation, it is concluded that the theoretical predictions of the electron temperature and plasma density agree remarkably well with experimental data     

Development of various PS-b-P4VP micellar morphologies: fabrication of inorganic nanostructures from micellar templates

A liquid-phase method for preparing uniform-sized silica nanospheres (SNSs) 12 nm in size and their three-dimensionally ordered arrangement upon solvent evaporation have recently been pioneered by us. Here we report the successful control of the sphere sizes in the wide range from 14 to 550 nm by the seed regrowth method. In this method, the dispersion of SNSs 14 nm in size as seeds was prepared in the emulsion system containing Si(OEt)(4) (TEOS), water and arginine under weakly basic conditions (pH 9-10). An appropriate portion of this dispersion is added to the solution containing water, ethanol and arginine, and then TEOS is added. The additional TEOS introduced into the regrowth system contributed only to the resumed growth of the seeds, not to the formation of new silica particles. The size of interparticle pores was finely tuned by changing the size of the spheres. The preparation of three-dimensionally ordered porous carbons by using the colloidal array of silica nanospheres as a template is also reported.     

Hemoglobin as a Diagnosing Molecule for Biological Effects of Atmospheric-Pressure Plasma

The studies with proteins are necessary to understand the biological effects of atmospheric pressure plasma (APP). Among proteins, those with transient metal ions play key roles in many biological events and they are very sensitive to environmental redox states. Iron-containing hemoglobin (Hb) is investigated in this study, after APP treatments under two environmental gas conditions of pure N₂ and N₂?+?O₂ mixture. Monitoring the intensity change for absorption spectra could lead to a quantitative assessment of the effect of discharge plasma on Hb. Redox states of Hb are classified into five states including O₂-bound Hb (oxy-Hb), deoxy-Hb, met-Hb, NO-bound Hb (NO-Hb), and hemichrome. Chemically generated reactive species and some scavengers are applied to understand the chemical reactions. Our experimental results confirm the complex chemical reactions of APP and suggest the possible use of Hb as a model protein for the visualization of APP biological effects.