Safe Removal of the Allyl Protecting Groups of Allyl Esters using a Recyclable,Low‐Leaching and Ligand‐Free Palladium Nanoparticle Catalyst

A safe, facile and low‐leaching (up to 0.04 ppm) method has been developed for the removal of allyl, prenyl and benzyl protecting groups from the corresponding esters, using a sulfur‐modified gold‐supported palladium (SAPd) nanoparticle catalyst, which is known to be non‐flammable. The catalyst itself was found to be recyclable and the reaction appeared to proceed on the surface of the SAPd.

     

Relationship between perceived softness of bilayered skin models and their mechanical properties measured with a dual‐sensor probe

The development of a sensor system that can predict the subjective softness of human skin is an important goal for the cosmetics industry. Here, we first carried out a subjective softness evaluation test using 65 skin models consisting of polyurethane bilayers with different thickness of the superficial layer and different degree of cross‐polymerization of the basal layer. The results showed that perceived softness was dependent on the mechanical properties of both the superficial and basal layers. Then, we used a recently developed tactile sensor system composed of a piezoelectric tactile sensor and a load cell to measure mechanical softness parameters of the superficial layer and the whole model, respectively. Statistical analysis showed that the data obtained from these two sensors were well correlated with the perceived softness of the prepared models. These results suggest that it may be feasible to predict the subjective softness of human skin in vivo from non‐invasive mechanical softness measurements of the superficial skin layer and whole skin obtained with our new dual‐probe sensor system.     

A low-power low-noise accurate linear-in-dB variable-gain amplifierwith 500-MHz bandwidth

A linear-in-dB variable-gain amplifier (VGA) using a pre-distortion circuit to generate the gain-control signal is fabricated in a BiCMOS process with f_T=20 GHz. The VGA comprises two cascaded stages of signal-summing VGA and has a variable-gain range of over 70 dB. It can operate at up to 500 MHz and dissipates 36 mW from a 3-V supply. A noise figure of below 5 dB and IIP3 of over -38 dBm at 43-dB gain were obtained. The VGA achieved a gain error of less than 2 dB over 70-dB gain range, and it occupies approximately 1 mm². The VGA is applicable to future code division multiple access (CDMA) receivers     

FIRE RESISTANCE CHARACTERISTICS OF MATERIALS WITH POLYMER GELS WHICH ABSORB AQUEOUS SOLUTION OF CALCIUM CHLORIDE

It is well known that moist fire protection materials show good fire resistance characteristics. For this reason, these materials are usually made of mixtures of perlite-mortar and high-water-content materials such as silica gels or moist perlites. The latent heat of water plays an important role in the resistance of heat propagation in these materials. A superabsorbent polymer gel that absorbs calcium chloride solution contains much water, and it is one of these high-water-content materials. In this study, numerical simulations of fire resistance tests were conducted for materials of different mixing ratio of perlite-mortar and the super absorbent polymer gel to investigate the effect of the mixing ratio on the fire resistance characteristics. The effective thermal conductivity and the water content of the materials were measured and those values were used for computations. One of the test materials shows excellent fire resistance characteristics, and its fire resistance time at 60 mm thick is about 300 min. The relations of thermal properties and composition of the test material and the effects of mixing ratio of the gels and the perlite-mortar on the fire resistance characteristics are discussed.     

Influence of plasma heating of wafer substrates on SiO2 deposition rate in a TEOS/O2 high-density plasma CVD system

The influence of plasma heating of the Si and glass wafer substrates on silicon dioxide (SiO₂) deposition rates by a tetraethylorthosilicate/O₂ supermagnetron (high-density) plasma CVD were investigated. With a fixed RF power of 100 W supplied to both upper and lower electrodes, the SiO₂ deposition rate on the Si wafer substrate decreased with increasing wafer-stage temperature, showing a negative activation energy for the deposition rate. When Si and glass wafers were attached to the electrode using adherent thermal conductors, the film thickness increased almost linearly with regard to the deposition time, and both deposition rates became almost the same (about 310 Å/min). When both wafers were simply laid on the electrode without an adhesive bond and hence with poor thermal contact, the film thickness increased nonlinearly with deposition time, showing a gradual decrease in deposition rate with time, being as low as 80 and 150 Å/min, respectively for Si and glass wafers, for a deposition time of 15 min. The difference between the two deposition rates on Si and glass wafers in the case of poor thermal contact to the lower electrode is thought to be caused by plasma heating and related mainly to differences in optical absorption characteristics of the two wafer substrates. Variations in measured thickness distributions across the substrate surface were attributed to an antisymmetric plasma density distribution in the direction perpendicular to the magnetic field lines caused by E×B electron drift.     

Development of a reduction-responsive amino acid that induces peptide bond cleavage in hypoxic cells

Hypoxia-responsive amino acids are indispensable in the preparation of hypoxic tumor-specific peptidyl prodrugs. In this paper, the design and synthesis of a reduction-responsive amino acid that induces peptide bond cleavage after reduction of the nitro group are described. Application to hypoxia-responsive peptide bond cleavage system is also reported.