Limonene and Related Compounds as Potential Skin Penetration Promoters

A transdermal therapeutic system can be developed by promoting the skin permeability of drugs with some materials. In this study, the promoting effect of terpenes present in essential oils on the percutaneous absorption of indomethacin from alcoholic hydrogels was investigated in rats in vivo. The enhancing activity of terpenes was expressed quantitatively as a quadratic function of lipophilicities of the terpenes, measured as a lipophilic index. Further increase in the significant level was observed when the molecular weight of terpenes was included in this function as the second factor. The synergism of ethanol with d-limonene, selected from among the other terpenes, on the promoting activity was statistically investigated. It was evident that both d-limonene and ethanol were important factors for promoting the percutaneous absorption of indomethacin. A significant synergism of d-limonene with ethanol was also observed. As a possible mechanism for enhancement action of d-limonene and ethanol, it was considered that, at first, d-limonene penetrates into the skin under coexistence with ethanol and may change the barrier structure of the stratum corneum. The transfer of ethanol to the skin is thereby enhanced under the coexistence with d-limonene in the skin. Thus, the permeation of indomethacin can be promoted due to its affinity with ethanol.     

New model for the high modulus and strength performance of ultradrawn polyethylenes

A new morphological model is discussed which is based on the relation of tensile modulus and strength to the macrofibrillar dimensions (aspect ratio) and the shear modulus of ultrahigh molecular weight polyethylene fibrillar structures of draw ratio DR ≤ 200–300. Such structures were obtained by solid state deformation of the as-received powder and solution grown crystals using an extrusion-drawing process. According to this model, the highest tensile modulus and tensile strength values that can be obtained are 212 GPa and 13.3 GPa, i.e., significantly close to the theoretically calculated values.     

Use of NIR spectroscopy for estimation of FA composition of soy flour

The feasibility of NIR spectroscopy for the determination of FA composition in soy flour was examined. NIR spectra were obtained for a small amount of soybean powder (about 8 mg) in a modified single-grain cup using an NIR instrument by scanning the wavelengths from 1100 to 2500 nm at 2-nm intervals. The relationship between the NIR spectral patterns of soybean powder and the FA compositions was examined: As the linoleic acid ratio increased, the NIR absorbance at 1708 nm, where the linoleic acid moiety has an absorption band, became stronger downward in the second-derivative NIR spectra. The correlation coefficients between the standardized NIR readings at 1708 nm and the linoleic acid ratio or the oleic acid ratio in the FA composition of soy flour were −0.853 and 0.877, respectively. A rough estimation of the linoleic acid moiety or oleic acid moiety in soy flour could be successfully carried out with even a very small amount of soy flour according to the NIR spectral pattern due to the wavelength assignments of moieties.     

A different regime of nanostructured diamond film growth

A different regime of diamond growth was found out in microwave plasma chemical vapor deposition by applying a different combination of growth conditions (pressure, microwave power, bias voltage, and bias current). This different regime of growth was identified by high-resolution transmission electron microscopy. In this regime, at lower bias current density (BCD), nanocrystals of diamond were confined in a form of nano-diamond rods 10-30 nm in diameter and several hundred nanometers long. More interestingly, at relatively high BCD, the film consists of a high packing density of even smaller size (2-5 nm) of diamond that generates enormous stress in thin film. Our finding of this different regime of growth offers the promise of exploring new properties of carbon materials.     

Simple photomultiplier tube internal-gating method for use in subnanosecond time-resolved spectroscopy

We propose a simple photomultiplier tube (PMT) internal-gating method for use in the field of subnanosecond time-resolved spectroscopy. In the proposed method, we control two dynodes in the PMT by applying a gate signal whose pulse width is Tg. When controlling the mth and the n(> m)th dynodes, a resolution time delta t is approximately given by delta t = Tg-(n-m) tau, where tau is a transit time of a lump of secondary electrons traveling between the two dynodes in the PMT. In principle, the resolution time delta t shorter than the pulse width Tg of the gate signal can be easily obtained. From a fundamental performance test, we found that a subnanosecond resolution time delta t = 0.31 ns was obtained for the case of m = 2 and n = 5. To demonstrate the effectiveness of the proposed method, we carried out a time-resolved spectroscopic measurement of emission obtained from a white-light-emitting diode (LED) driven by a nanosecond current pulse.     

Mixed Electronic-Ionic Conduction in Ru-Doped SrTiO3 at High Temperature

The electronic and ionic conduction behavior of Ru-doped SrTiO₃ at high temperature was investigated. The conductivity increased significantly with increasing Ru content. SrTi_0.80Ru_0.20O_3– exhibits fairly high conductivities, e.g., 3 S cm^–1 at 1000°C, and 2 S cm^–1 at 600°C. The conductivity had only a slight dependence on the partial pressure of oxygen over a wide range and was largely attributed to n-type electronic conduction. Ru-doped SrTiO₃ showed mixed oxide-ionic and electronic conduction under reducing atmospheres. The mechanism of the electronic and ionic conduction is discussed.     

Intrinsic stage i crack growth of directionally solidified Ni-Base superalloys during low-cycle fatigue at elevated temperature

Strain-controlled low-cycle fatigue tests of cylindrical smooth specimens of two kinds of directionally solidified Ni-base superalloys, RENé 80+Hf and CM 247LC, were carried out at a temperature of 873 K, and the successive process from the crack initiation to small crack propagation was investigated by employing a replication technique. Both materials exhibited typical features of stage I fatigue fracture; that is, the fracture occurred on the crystallographic 111 planes, the most important slip planes in face-centered cubic (fcc) materials. It was found that the rate of stage I crack growth, when not influenced by a nearby grain boundary, proportionally increased with the crack length. However, as the crack tip neared a grain boundary, the rate rapidly decreased. It was also shown that the crack growth rate fell when the crack deflection occurred due to secondary slip. Comparison was also made between the stage I crack growth rate and the long crack growth rate in polycrystalline Ni-base superalloys.     

Corrosion study in TbFeCoCr amorphous magneto-optical films

(Tb₂₀Fe₆₅Co₁₅)₉₄Cr ₆ film shows high corrosion resistance with good magnetooptical properties, H_c=4.9 kOe, &thetas;_k=0.3°, K_u=1.4×10⁶ erg/cm³ and T_c=230°C. Pit corrosion in 1N-NaCl aqueous solution and wet corrosion in 85°C and 85%RH atmosphere were studied for TbFeCo films with and without Cr addition. It is suggested that pit corrosion occurs by a chemical reaction between the anodic pit wall and the cathodic film surface, resulting in a piling up of corroded products inside the pits. On the other hand, wet corrosion in TbFeCo and TbFeCoCr films shows a bubble-chain-like morphology similar to conventional filiform corrosion observed in a coated film. This seems to take place by discontinuous movement of the anodic reaction area ahead of the bubbles