Currents and Electric Fields Induced in Anatomically Realistic Human Models by Extremely Low Frequency Electric Fields

There is increasing public concern about biological interactions with and the potential health effects of low frequency electric and magnetic fields. Recently, the ICNIRP （International Commission on Non-Ionizing Radiation Protection） has published new exposure guidelines with regard to these fields. The aim of this paper is to demonstrate the calculation of the currents and electric fields induced in the human body by external electric fields at 60 Hz, using numerical human models of anatomically-realistic human bodies, and to compare those results with the basic restrictions proposed by the new guidelines. As a result, in the case that a human is exposed to an electric field of 1 kV/m at 60 Hz the short-circuit current of 18 μA flows though the ankles. Furthermore, the electric field of 40 mV/m in the nervous tissue of the adult model is induced by exposure to external electric fields at the reference level, which is enough smaller than the basic restrictions established in the ICNIRP guidelines for occupational exposure.     

Skin Permeation of Lidocaine from Crystal Suspended Oily Formulations

ABSTRACT

In vitro permeation of lidocaine (lidocaine base, LID) through excised rat skin was investigated using several LID-suspended oily formulations. The first skin permeation of LID from an LID-suspended oily solution such as liquid paraffin (LP), isopropyl myristate (IPM), polyoxyethylene (2) oleylether (BO-2), and diethyl sebacate (DES) was evaluated and compared with that from polyethylene glycol 400 (PEG400) solution, a hydrophilic base. The obtained permeation rate of LID, J_app, from PEG400, LP, IPM, BO-2, and DES was in the order of DES>BO-2 = IPM>LP>PEG400, and increased with LID solubility in the oily solvents, although LID crystals were dispersed in all solvents. Subsequently, oily formulations that consisted of different ratios of the first oily solvent (IPM, BO-2, or DES) (each 0–20%), the second oily solvent (LP) and an oily mixture of microcrystalline wax/white petrolatum/paraffin (1/5/4) were evaluated. BO-2 groups at a concentration of 5% and 10% had the highest J_app among the oily formulations, although a higher BO-2 resulted in lower skin permeation. In addition, pretreatment with BO-2 increased the skin permeation of LID. These results suggest that the penetration enhancing effect by the system may be related to the skin penetration of BO-2 itself. Finally, mathematical analysis was done to evaluate the effect of BO-2, and it was shown that BO-2 improved the LID solubility in stratum corneum lipids to efficiently enhance the LID permeation through skin.     

Photo-induced molecular alignment of azo dye derivative

Photo-induced molecular alignment behavior of azo dye derivative (sodium 4,4′-bis (4-hydroxy-3-carboxy-phenylazo) benzidine-2,2′-disulphonate: SD1) was investigated using SD1 film prepared by spin-coating method. As-prepared SD1 film was composed of an amorphous layer with smooth surface. Upon linearly polarized UV light irradiation, the film surface was roughened slightly and X-ray diffraction measurement and transmittance electron microscope observation indicated that SD1 molecules crystallized with orientation. Molecular plane of SD1 aligned parallel to the substrate surface along the normal to the polarization direction of irradiated UV light through the trans-cis and cis-trans isomerizations of the azobenzene chromophore.     

Chemical transformation of chiral monolayer-protected gold clusters: observation of ligand size effects on optical and chiroptical responses

Versatile functionalization of metal clusters is a key step in understanding the reactivity of protective monolayers. We here demonstrate that reaction of the outermost amino groups on (S)-/(R)-penicillamine-protected gold clusters with ethyl isocyanate readily modifies the chiral surface structure through carbamoylation. Interestingly, the clusters are electrophoretically separated by the size of the surface ligand, not by the size of the gold core, which is revealed by UV-vis, IR, and energy dispersive X-ray (EDX) spectroscopy as well as SAXS measurements. The ligand size (or length) is extended through additional reactions of the carbamoylated amino groups with isocyanate, while the chemical similarity in ligand structures is realized by their IR spectral similarity. Optical and chiroptical responses of the separated cluster compounds are thus overall similar to each other, but a close inspection reveals that the ligand size has a small but distinct influence on the chiroptical response of the gold clusters.     

Comprehensive evaluation of leukocyte lineage derived from human hematopoietic cells in humanized mice

Recently, humanized animals whereby a part of the animal is biologically engineered using human genes or cells have been utilized to overcome interspecific differences. Herein, we analyzed the detail of the differentiation states of various human leukocyte subpopulations in humanized mouse and evaluated comprehensively the similarity of the leukocyte lineage between humanized mice and humans. Humanized mice were established by transplanting human CD34(+) cord blood cells into irradiated severely immunodeficient NOD/Shi-scid/IL2Rγ(null) (NOG) mice, and the phenotypes of human cells contained in bone marrow, thymus, spleen and peripheral blood from the mice were analyzed at monthly intervals until 4 months after cell transplantation. The analysis revealed that transplanted human hematopoietic stem cells via the caudal vein homed and engrafted themselves successfully at the mouse bone marrow. Subsequently, the differentiated leukocytes migrated to the various tissues. Almost all of the leukocytes within the thymus were human cells. Furthermore, analysis of the differentiation states of human leukocytes in various tissues and organs indicated that it is highly likely that the human-like leukocyte lineage can be developed in mice.     

Styrene–butadiene rubber/cellulose II/clay nanocomposites prepared by cocoagulation—mechanical properties

In this work, nanocomposites of styrene butadiene rubber (SBR), cellulose II, and clay were prepared by cocoagulation of SBR latex, cellulose xanthate, and clay aqueous suspension mixtures. The incorporated amount of cellulose II was 15 phr, and the clay varied from 0 to 7 phr. The influence of cellulose II and clay was investigated by rheometric, mechanical, physicochemical, and morphological properties. From the analysis of transmission electron microscopy (TEM), dispersion in nanometric scale (below 100nm) of the cellulosic and mineral components throughout the elastomeric matrix was observed. XRD analysis suggested that fully exfoliated structure could be obtained by this method when low loading of silicate layers (up to 5 phr) is used. The results from mechanical tests showed that the nanocomposites presented better mechanical properties than SBR gum vulcanizate. Furthermore, 5 phr of clay is enough to achieve the best tensile properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Relation of the polymeric ion species in plasma to the hardness of a-C:H film made by PSII&D

The amorphous carbon (a-C:H) films formed by plasma source ion implantation and deposition (PSII&D) have expanded the tribological properties. Especially, the hardness can be widely changed by adequately selecting RF power, pulse bias voltage, gas species and gas pressure. Previously, we reported that a-C:H film hardness depended on the electron temperature in C₂H₂ plasma which was ignited with pulsed RF power, and that the hardness was in inverse proportion to the electron temperature in the range of less than 2.5 eV. We have discovered that the film hardness is, in some cases, changing even if the electron temperature is constant. This suggests that there are some new factors to determine the film hardness besides the electron temperature in the plasma. In this study, we employ a quadrupole mass spectrometer to measure the intensity of each polymeric ion in C₂H₂. The film hardness is determined by the synergy of the polymeric ion abundances and ion irradiation.     

Characterization of multi-input electroretinogram using normal control subjects

BACKGROUND: The multi-input electroretinogram (ERG) has recently been developed to analyze focal retinal responses in the central region and is expected to become a powerful tool for management of retinal diseases. The relationship between the obtained ERG response and retinal neuronal functions is not yet fully understood. METHOD: In the present study, in order to study the spatial retinal functions; multi-input ERGs were recorded from 14 healthy subjects under several illumination conditions modulating photoreceptor functions. RESULTS: The first-order kernel amplitudes were changed in correspondence to the cone photoreceptor adaptation states under different background illuminations. A strong flash exposure significantly lowered the amplitude (approximately 70%) within the central 15 deg but lowered it only slightly (10-20%) in the peripheral areas outside the central 15 deg. Similar effects were observed when the stimulus luminance was lowered by neutral density filters. CONCLUSION: Our data suggest that a newly developed multi-input measurement of ERGs represents signals within the firing of postreceptor neurons from cone photoreceptors at specific areas. Thus, this analysis is a useful tool for mapping the spatial network of neurons in the central region.