Extracellular matrix production regulation by TGF-beta in corneal endothelial cells

PURPOSE: Production of extracellular matrix (ECM) by corneal endothelial cells is related to physiologic functions and pathologic conditions and is regulated by many cytokines, including transforming growth factor-beta (TGF-beta). In this study, the molecular mechanism of ECM production regulation by TGF-beta was investigated in cultured corneal endothelial cells. METHODS: The production of ECM components (laminin and fibronectin) was detected in cultured corneal endothelial cells by western blot analysis. To determine the signal transduction pathways, mutant TGF-beta type I receptor (TbetaR-I) and/or Smad protein family members (intracellular signal transducers in TGF-beta signaling) were overexpressed by transfecting their cDNA into the cultured cells, and the effects on ECM production were observed. RESULTS: The production of laminin and fibronectin was stimulated by treatment with TGF-beta1 or TGF-beta2. After transient transfection of cDNA of the constitutively active (CA) mutant of TbetaR-I, the production of laminin and fibronectin was stimulated even in the absence of TGF-beta. The transfection of the dominant negative mutant of TbetaR-I counteracted the effects of TGF-beta. These results confirm that TGF-beta directly stimulates ECM production from corneal endothelial cells through TbetaR-I. The ECM production stimulation by TGF-beta or CA TbetaR-I was accelerated by the overexpression of Smad2, Smad3, and/or Smad4 and inhibited by that of Smad7. These results show that TGF-beta signals connected to ECM production are regulated by Smad family members, located downstream of TbetaR-I. CONCLUSIONS: The results of this study show that TGF-beta stimulates ECM production from corneal endothelial cells through TbetaR-I and Smad family transducers.     

Hydrogen Permeation Properties and Hydrothermal Stability of Sol–Gel‐Derived Amorphous Silica Membranes Fabricated at High Temperatures

The sol–gel method was applied to the fabrication of amorphous silica membranes for use in hydrogen separation at high temperatures. The effects of fabrication temperature on the hydrogen permeation properties and the hydrothermal stability of amorphous silica membranes were evaluated. A thin continuous silica separation layer (thickness = <300 nm) was successfully formed on the top of a deposited colloidal silica layer in a porous glass support. After heat treatment at 800°C for an amorphous silica membrane fabricated at 550°C, however, it was quite difficult to distinguish the active separation layer from the deposited colloidal silica layer in a porous glass support, due to the adhesion of colloidal silica caused by sintering at high temperatures. The amorphous silica membranes fabricated at 700°C were relatively stable under steam atmosphere (500°C, steam = 70 kPa), and showed steady He and H₂ permeance values of 4.0 × 10^?7 and 1.0 × 10^?7 mol·m^?2·s^?1·Pa^?1 with H₂/CH₄ and H₂/H₂O permeance ratios of ~110 and 22, respectively. The permeance ratios of H₂/H₂O for membranes fired at 700°C increased drastically over the range of He/H₂ permeance ratios by factors of ~3–4, and showed a value of ~30, which was higher than those fired at 500°C. Less permeation of water vapor through amorphous silica membranes fabricated at high temperatures can be ascribed to the dense amorphous silica structure caused by the condensation reaction of silanol groups.     

Effect of Al on the galvanic ability of Zn-Al coating under thin layer of electrolyte

The effect of Al on the galvanic ability of Zn-Al coating has been studied under thin electrolyte layers by measuring surface potential and surface pH. The changes of surface potential and surface pH over Zn-Al/steel galvanic couple corroding in artificial sea water (ASW) were measured at 60% and 90% RH at 298 K. In the initial stage of corrosion, Zn-55Al coating has shown better galvanic protection ability than Zn-5Al coating in both 60% and 90% RH. However, Zn-5Al coating was better in long term corrosion. The better galvanic ability of Zn-55Al coating in the initial stage of corrosion was related to the observation of pH as low as low as 2 on its surface. The low pH value was due to hydrolysis of Zn²⁺ and Al³⁺ ions. The low pH value was further confirmed by observing evolution of gas due to H⁺ reduction on the Zn-55Al coating. With the progress of corrosion, the low pH region of coating layer extended towards the base steel. This helped expand the deposition of zinc corrosion products on the steel surface. The enhanced dissolution of zinc in Zn-55Al coating led to the formation of a barrier layer which limited the galvanic protection of remaining steel. This was not the case in Zn and Zn-5Al coating. The X-ray analyses of the corroded samples have shown the deposition of zinc corrosion products on the steel surface, which greatly depended on the RH value. The part of the steel surface covered with zinc corrosion products has shown relatively less noble potential than other part indicating that zinc corrosion products took a role to protect the base steel against corrosion. The results from surface potential and surface pH measurements were substantiated by the surface observation of the corroded sample during and after the corrosion test.     

Ferroelectric Liquid Crystals with an alkanoyl group

Recent studies on ferroelectric liquid crystals (FLCs) with an alkanoyl group are reviewed in this article. The FLCs exhibit large spontaneous polarization, especially when another chiral group is introduced at the opposite side of the core. The maximum value reaches 1130 nC/cm², which is almost the same as the total transverse dipole in the molecule. Fastswitching FLC mixtures can be obtained by using these compounds. The synthesis and properties of FLC polymers having the same mesogen and chiral group are also described, and some applications of the FLC mixtures in devices for optical communication reported.     

Mechanical properties and microstructure of bioactive ORMOSILs containing silica particles

We synthesized organically modified silicate (ORMOSILs) gels with colloidal silica (CS) (AEROSIL®) starting from polydimethylsiloxane (PDMS), tetraethoxysilane (TEOS) and calcium nitrate (Ca(NO₃)₂·4H₂O) through sol–gel processing. Dynamic mechanical analysis indicated that relative height of the tanδ peak at about −100 °C increased with an increase in the relative content of the inorganic components. This peak growth was accounted for by the relative increase in PDMS–colloidal silica particle interactions. The colloidal silica could control the mechanical behavior of the hybrids. The gel of a specific composition could deposit apatite within 3 days of soaking in the simulated body fluid (SBF), since it included many calcium ions on the surface.     

A 4.1-ns compact 54×54-b multiplier utilizing sign-selectBooth encoders

A 54×54-b multiplier with only 60 K transistors has been fabricated by 0.25-μm CMOS technology. To reduce the total transistor count, we have developed two new approaches: sign-select Booth encoding and 48-transistor 4-2 compressor circuits both implemented with pass transistor logic. The sign-select Booth algorithm simplifies the Booth selector circuit and enables us to reduce the transistor count by 45% as compared with that of the conventional one. The new compressor reduces the count by 20% without speed degradation. By using these new circuits, the total transistor count of the multiplier is reduced by 24%. The active size of the 54×54-b multiplier is 1.04×1.27 mm and the multiplication time is 4.1 ns at a 2.5-V power supply     

Ammonia decomposition in catalytic membrane reactors: Simulation and experimental studies

Catalytic decomposition of NH₃ with H₂‐selective microporous silica membranes for CO_x‐free hydrogen production was studied theoretically and experimentally. The simulation study shows that NH₃ conversion, H₂ yield and H₂ purity increase with the Damköhler number (Da), and their improvement is affected by the effect of H₂ extraction as well as NH₃ and N₂ permeation through the membranes. The experimental study of NH₃ decomposition was carried out in a bimodal catalytic membrane reactor (BCMR), consisting of a bimodal catalytic support and a H₂‐selective silica layer. Catalytic membranes showed H₂ permeances of 6.2–9.8 × 10^?7 mol m^?2 s^?1 Pa^?1, with H₂/NH₃ and H₂/N₂ permeance ratios of 110–200 and 200–700, respectively, at 773 K. The effect of operating conditions on membrane reactor performance with respect to NH₃ conversion, H₂ yield and H₂ purity was investigated, and the results were in agreement with those calculated by the proposed simulation model. © 2012 American Institute of Chemical Engineers AIChE J, 59: 168–179, 2013     

Network-supported TCP rate control for high-speed power line communications environments

High-speed power line communications (PLC) technology has great potential to serve as an infrastructure for home networking. To investigate the performance of end-to-end data flows over high definition (HD)-PLC, we have developed a new module on the NS-2 network simulator for HD-PLC that is driven by the particular patterns of the time-varying packet-error-rate as measured by experiments. To solve the problem on coexisting multiple TCP flows, a novel network-supported TCP rate control that appropriately modifies the advertized-window value in a TCP-ACK packet in response to the PLC network condition is presented and is shown to be effective through simulations.     

Analytical evaluation of dielectric breakdown test based on one-minute step-up method

The authors previously pointed out that the results of insulation tests based on the oneminute step-up method deviate from the ?true values?. In the present study, these deviations are evaluated by numerical simulations. These deviations were found to exist not only under limited conditions in numerical simulations but to exist fundamentally on the one-minute step-up test method. This should be taken into consideration when making actual insulation designs.     

The antero-posterior diameter of the cervical spinal canal in cervical spondylosis (author's transl)

1. The antero-posterior diameter (APD) of the cervical spinal canals in 96 healthy adults, 108 cases of radiological cervical spondylosis (asymptomatic) and 96 cases of cervical spondylosis with radiculopathy or radiculomyelopathy was measured for each vertebra by the method of Burrows. (Filmfocus distance was 1.2m). 2. The APD in patients with symptomatic spondylosis was found to be significantly narrower than those of without. 3. Since the upper limit of APD at C4 to C6 vertebrae in symptomatic spondylosis was 16 mm, while the lower limit of APD in asymtomatic spondylosis was 14 mm, the following conclusion appears justified. 1) When the APD is narrower than 16 mm, the osteophytes along the posterior border of the spinal bodies or degenerative disc protrusions may produce cervical radiculomyelopathy, although the cord and the roots may escape from compression by the spondylotic changes even when the APD is wider than 14 mm. 2) When the APD is narrower than 13 mm, it is almost always certain that the osteophytes or herniated discs compress the cervical cord and roots.