Intestinal absorption and biological effects of orally administered amorphous silica particles

Although amorphous silica nanoparticles are widely used in the production of food products (e.g., as anticaking agents), there is little information available about their absorption and biological effects after oral exposure. Here, we examined the in vitro intestinal absorption and in vivo biological effects in mice of orally administered amorphous silica particles with diameters of 70, 300, and 1,000 nm (nSP70, mSP300, and mSP1000, respectively) and of nSP70 that had been surface-modified with carboxyl or amine groups (nSP70-C and nSP70-N, respectively). Analysis of intestinal absorption by means of the everted gut sac method combined with an inductively coupled plasma optical emission spectrometer showed that the intestinal absorption of nSP70-C was significantly greater than that of nSP70. The absorption of nSP70-N tended to be greater than that of nSP70; however, the results were not statistically significant. Our results indicate that silica nanoparticles can be absorbed through the intestine and that particle diameter and surface properties are major determinants of the degree of absorption. We also examined the biological effects of the silica particles after 28-day oral exposure in mice. Hematological, histopathological, and biochemical analyses showed no significant differences between control mice and mice treated with the silica particles, suggesting that the silica nanoparticles evaluated in this study are safe for use in food production.     

High speed GaAs digital integrated circuit with clock frequency of 4.1 GHz

A maximum clock frequency of 4.1 GHz was obtained for a GaAs digital integrated circuit using deep recess normally-on GaAs MESFETs with 1.2 ?m long gate and interdigitated Schottky diodes. The Ti/Pt/Au gate electrode was made by a lift-off technique with conventional photolithography. The minimum propagation delay of a NAND/AND gate was estimated to be 100 ps/gate for a fan-out of 2 from the self-oscillation frequency of the master-slave flip-flops.     

GaAs power m.e.s.f.e.t.s. with a graded recess structure

A new recess structure device was developed to improve the field distrubution and therfore the performance of GaAs power m.e.s.f.e.t.s. The linear gain and the output power were improved by 1?2 dB for this structure. The highest output powers obtained are 15 W with 4 dB associated gain at 6 GHz, and 4.3 W with 3 dB associated gain at 11 GHz.     

Effects of capacitance at crossover wirings in power GaAs m.e.s.f.e.t.s.

Power GaAs f.e.t.s. with an air-bridge crossover were compared with those of SiO2 crossover to find the effect of the capacitance at the crossover points. The capacitance of SiO2 crossover points is much smaller than that of the gate pad or the gate busbar in power GaAs f.e.t.s, and deterioration of the microwave performance due to that capacitance is negligible.     

Promotion of allergic immune responses by intranasally-administrated nanosilica particles in mice

With the increase in use of nanomaterials, there is growing concern regarding their potential health risks. However, few studies have assessed the role of the different physical characteristics of nanomaterials in allergic responses. Here, we examined whether intranasally administered silica particles of various sizes have the capacity to promote allergic immune responses in mice. We used nanosilica particles with diameters of 30 or 70 nm (nSP30 or nSP70, respectively), and conventional micro-sized silica particles with diameters of 300 or 1000 nm (nSP300 or mSP1000, respectively). Mice were intranasally exposed to ovalbumin (OVA) plus each silica particle, and the levels of OVA-specific antibodies (Abs) in the plasma were determined. Intranasal exposure to OVA plus smaller nanosilica particles tended to induce a higher level of OVA-specific immunoglobulin (Ig) E, IgG and IgG1 Abs than did exposure to OVA plus larger silica particles. Splenocytes from mice exposed to OVA plus nSP30 secreted higher levels of Th2-type cytokines than mice exposed to OVA alone. Taken together, these results indicate that nanosilica particles can induce allergen-specific Th2-type allergic immune responses in vivo. This study provides the foundations for the establishment of safe and effective forms of nanosilica particles.     

Size and surface modification of amorphous silica particles determine their effects on the activity of human CYP3A4 in vitro

Because of their useful chemical and physical properties, nanomaterials are widely used around the world - for example, as additives in food and medicines - and such uses are expected to become more prevalent in the future. Therefore, collecting information about the effects of nanomaterials on metabolic enzymes is important. Here, we examined the effects of amorphous silica particles with various sizes and surface modifications on cytochrome P450 3A4 (CYP3A4) activity by means of two different in vitro assays. Silica nanoparticles with diameters of 30 and 70 nm (nSP30 and nSP70, respectively) tended to inhibit CYP3A4 activity in human liver microsomes (HLMs), but the inhibitory activity of both types of nanoparticles was decreased by carboxyl modification. In contrast, amine-modified nSP70 activated CYP3A4 activity. In HepG2 cells, nSP30 inhibited CYP3A4 activity more strongly than the larger silica particles did. Taken together, these results suggest that the size and surface characteristics of the silica particles determined their effects on CYP3A4 activity and that it may be possible to develop silica particles that do not have undesirable effects on metabolic enzymes by altering their size and surface characteristics.     

High‐resolution and high‐brightness full‐colour “Silicon Display” for augmented and mixed reality

High‐brightness micro‐LED display bonded onto silicon backplane has been successfully demonstrated. The 0.38‐inch full‐colour active matrix LED microdisplay system consists of 352 × 198 pixels. Each pixel is 24 μm square composed of red, green, and blue (RGB) subpixels corresponding to a pixel resolution of 1053 ppi. Quantum‐dot materials are formed on III‐nitride blue micro‐LED array to convert blue light into red and green for full‐colour operation. We have confirmed that this microdisplay, which we call “Silicon Display” has wide colour gamut exceeding 120% of sRGB. We describe the advantage of this colour‐converting approach for the full‐colour micro‐LEDs. Progress toward higher resolution is also described. Brightness of more than 30 000 cd/m² has been confirmed at a driving current density of 4 A/cm² for 3000 ppi blue monochrome micro‐LED prepared for full‐colour Silicon Display. We believe our “Silicon Display” is ideally suited for near‐to‐eye displays for augmented and mixed reality.     

GaAs DCFL 2.5 Gbps 16-bit Multiplexer/Demultiplexer LSI's

GaAs 2.5 Gbps 16 bit MUX/DEMUX LSI's have been successfully developed. DCFL is employed as a basic gate in order to reduce the power dissipation. To avoid the speed degradation caused by using DCFL, various technologies such as 8×2(MUX)/2×8(DEMUX) data conversion processes, a Selector Merged Shift Register, clock overlapping, and a 0.7-μm BPLDD MESFET, have been introduced. Moreover the ECL I/O level interface and single power supply features make it easy to use MUX/DEMUX in optical communication systems. The maximum operating data rate is 3.2 Gbps for both LSI's, and the power dissipation of chips which operates with 2.5 Gbps are as low as 1.3 W for each MUX/DEMUX     

Effect of amorphous silica nanoparticles on in vitro RANKL-induced osteoclast differentiation in murine macrophages

Amorphous silica nanoparticles (nSP) have been used as a polishing agent and/or as a remineralization promoter for teeth in the oral care field. The present study investigates the effects of nSP on osteoclast differentiation and the relationship between particle size and these effects. Our results revealed that nSP exerted higher cytotoxicity in macrophage cells compared with submicron-sized silica particles. However, tartrate-resistant acid phosphatase (TRAP) activity and the number of osteoclast cells (TRAP-positive multinucleated cells) were not changed by nSP treatment in the presence of receptor activator of nuclear factor κB ligand (RANKL) at doses that did not induce cytotoxicity by silica particles. These results indicated that nSP did not cause differentiation of osteoclasts. Collectively, the results suggested that nanosilica exerts no effect on RANKL-induced osteoclast differentiation of RAW264.7 cells, although a detailed mechanistic examination of the nSP70-mediated cytotoxic effect is needed.     

An AlGaAs/InGaAs pseudomorphic HEMT modulator driver IC with lowpower dissipation for 10-Gb/s optical transmission systems

An optical modulator driver integrated circuit (IC) has been developed for 10-Gb/s optical communication systems. To achieve both high-frequency (HF) operation and low power dissipation, 0.2-μm T-shaped gate AlGaAs/InGaAs pseudomorphic high electron-mobility transistors (HEMTs) have been employed for their large transconductance g_m of 610 mS/mm and high cutoff frequency f_T of 67.5 GHz. In addition, optimizing input logic swing, switching transistor size in the output driver, and using cascode-current mirror circuits with small output conductance enable power dissipation as low as 1 W to be achieved at a 10-Gb/s nonreturn-to-zero (NRZ) signal output with 3 V_p._p. This is the lowest value ever reported for power dissipation. As an additional function, the output-voltage swing can be controlled in the range from 2 to 3.3 V_p._p. by the current mirror circuit for the purpose of adjusting the optical-output-signal duty factor through an optical modulator