Glass transition behavior of hyper-branched polystyrenes

Hyper-branched polystyrenes (HBPS) were synthesized. The bulk glass transition temperature (T_g) measured by differential scanning calorimetry (DSC) for two kinds of HBPS with an equivalent M_w, which were fractionated from different lots, were different, being respectively higher and lower than that of the corresponding linear polystyrene (PS). Infrared spectroscopy revealed that the T_g of HBPS increased with an increasing extent of intramolecular cross-linking, or cyclization, in the molecule. The segmental dynamics of HBPS was examined by dynamic mechanical analysis. The relaxation temperature for the segmental motion in HBPS was consistent with the DSC results. The fragility index was always lower for HBPS than for the linear PS, regardless of its primary structure and chain end chemistry. This would indicate that the segmental motion for HBPS is less cooperative than that of the linear PS, probably due to a lack of intermolecular chain entanglements in HBPS.     

Ozonation Of Seawater - Applicability Of Ozone For Recycled Hatchery Cultivation

It is known that oxidants remaining in ozonated seawater give harmful effects to fishes. This is one of the reasons restricting applications of ozone for disinfection and quality improvements of seawater used in hatcheries. In this study, fatal doses of the oxidants to larvae, reduction of the residual oxidants by activated carbon unit, and the possibility of recycled seawater in a hatchery using ozone and activated carbon were preliminarily investigated.

The residual oxidants were very harmful to larvae, and their reduction was indispensable to the cultivations. The oxidants were found to be easily removed by contacting with activated carbon. Ozonation in cooperation with sand and activated carbon filtrations was suggested to be effective for improving the rate of survival and water quality. It was also suggested that the oxidants were alternative to predicted the BrO or BrO₃ ions.     

Influence of Oxygen Adsorption on Surface Tension of Molten Nickel Measured Under Reducing Gas Atmosphere

The surface tension of molten nickel was measured under a reducing gas atmosphere of Ar–He–5 vol% H \(_{2}\) by an oscillating droplet method using electromagnetic levitation. The influence of the temperature dependence of the oxygen partial pressure of the gas on the surface tension was investigated. The surface tension of molten nickel was successfully measured over the very wide temperature range of 750 K, which included undercooling conditions. The temperature dependence of the surface tension did not exhibit a linear relationship but had a peculiar kink at around 1600 K, due to competition between the temperature dependence of the oxygen partial pressure and that of the oxygen adsorption equilibrium constant.     

Kinetic analysis of E. coli inactivation by high hydrostatic pressure with salts

Inactivation of E. coli by high hydrostatic pressure (250 to 400 MPa) with salts was investigated based on kinetic analysis. At concentrations from 0.074 to 0.145 M and from 0.240 to 0.290 M, both the absolute activation volumes and the preexponential factors were similar in KCl, NaCl, and LiCl solutions, suggesting that pressure inactivation is not salt-specific. On the other hand, in the intermediate salt-concentration range of 0.145 to 0.240 M, inactivation kinetics in the presence of the Na(+) and K(+) differed significantly from those in the presence of Li(+) (P < 0.05). In this concentration range, effect of salt stress and osmotic stress differed significantly from those in concentrations below 0.145 M or above 0.240 M. The cellular response to pressure varies with salt type and salt concentration. These novel findings provide important clues to distinguish between salt stress and osmotic stress in the inactivation of E. coli.     

Mechanical and scratch behaviors of polyrotaxane-modified poly(methyl methacrylate)

The mechanical and scratch behaviors of polyrotaxane (PR) modified poly(methyl methacrylate) (PMMA) were investigated. PR is a necklace-like supramolecule with rings threaded onto a linear backbone chain that is capped by bulky end groups. Cyclodextrin (CD) serves as the ring structure and can be functionalized to induce specific interactions with the hosting polymer matrix. To systematically investigate the effect of CD functionalization on the mechanical properties of PMMA, PR with polycaprolactone (PCL) grafted chains on CD, and PR with methacrylate functional groups at the terminal of the PCL grafted chains on CD were chosen for this study. Tensile and compressive true stress–strain tests, ASTM scratch test, and coefficient of friction measurements were conducted to fundamentally understand how PR influences the mechanical and scratch behaviors of PMMA. Additionally, dielectric relaxation spectroscopy and dynamic mechanical analysis were conducted to explore how PR influences the relaxation dynamics of PMMA. The above findings suggest that the methacrylate functional group on PR induces favorable molecular interactions with PMMA matrix, leading to enhanced molecular cooperativity during deformation, which in turn improves tensile and compressive properties and achieves greatly improved scratch resistance.     

Target-cell specificity of fusogenic liposomes: membrane fusion-mediated macromolecule delivery into human blood mononuclear cells

Fusogenic liposome, a unique vector prepared by fusing ultraviolet-inactivated Sendai virus and liposome, is known to efficiently deliver content into various animal cells through membrane fusion. In this study, we examined the target-cell specificity of fusogenic liposome (FL)-mediated macromolecule delivery into human blood cells using diphtheria toxin fragment A (DTA) as a probe. Among the peripheral blood mononuclear cells (PBMC), FL was able to deliver its encapsulates into CD14+ monocytes and CD4-/CD8- T-cells, but not into CD19+ B-lymphocytes, CD4+ T-cells or CD8+ T-cells. The susceptibility of human leukemia cell lines to FL was similar to that of PBMC; the order of the reactivity was U937 (monoblastic leukemia)>MOLT4, Jurkat (T-lymphoma)>Daudi, BALL1 (B-lymphoma)>K562 (erythroblastic leukemia). Interestingly, FL showed similar binding activity to all of these leukemia cell lines. These findings indicate that, among blood cells, monocytes, monoblastic leukemia cells, CD4-/CD8- T-cells and T-lymphoma cells are preferable targets for FL-mediated macromolecule delivery. This is the first demonstration of the existence of non-permissive cells against FL. Our results also suggest that some molecules on target-cells other than the binding targets of SV-derived protein may participate in fusion between FL and cells.     

Immunohistochemical localization of HLA-DR-positive cells in unerupted and erupted normal and carious human teeth

Class II major histocompatibility complex (MHC) antigen-expressing cells are generally associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, normal, and carious human teeth to clarify when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically by means of HLA-DR monoclonal antibody. In the pulp of unerupted developing teeth, numerous HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer, with slender cytoplasmic processes extending into the layer. Superficial caries lesions caused an aggregation of HLA-DR-positive cells in dental pulp corresponding to the lesion. In teeth with deeper caries lesions, this aggregation of cells expanded to include the odontoblast layer. Also noted were HLA-DR-positive cells lying along the pulp-dentin border, with cytoplasmic processes projecting deep into the dentinal tubules, where they co-localized with odontoblast processes. These findings suggest that: (1) human dental pulp is equipped with immunologic defense potential prior to eruption; (2) in the initial stage of caries infection, an immunoresponse mediated by class-II-expressing cells is initiated in human dental pulp; and (3) HLA-DR-positive cells trespass deep into dentinal tubules as the caries lesion advances.     

Optimized operations by extended X-factor theory including unithours concept

The relationships between tool performance, cycle time, and throughput have been described to achieve the highest productivity. Though tool utilization is low for manually operated tools, long waits prior to product processing lead to a productivity loss in our production line. We focus on operator efficiency in the CMP (chemical mechanical polishing) operation, which, as a typical manually operated tool, influences cycle time. This paper introduces an online/offline unit hour analysis method, which has been designed to optimize operator allocation and headcount in our production line, using X-factor theory in order to achieve the shortest cycle time. By using online/offline unit hour analysis with X-factor theory, the root cause of waiting time can be identified and the relationship between operator headcount and cycle time can be described. The waiting time can be reduced by 35% and the cycle time can be reduced by 25%, according to a simulator with optimized operator allocation and headcount based on online/offline unit hour analysis     

Delay-line PPAC for high-energy light ions

We have developed a delay-line parallel-plate avalanche counter (PPAC) with high detection efficiency for high-energy light ions. A large signal-to-noise ratio was achieved by a newly designed pre-amplifier and the usage of C₃F₈ gas at a pressure of 30 Torr. The counter has been tested with beams of 90 AMeV ⁷Li at RIKEN, 340 AMeV ¹²C at GSI, and 254 AMeV ⁸B at GSI. We achieved high detection efficiencies (>95%) for all of these ions. Furthermore, we achieved reasonable position and timing resolutions.