Elastic-plastic thermal stresses and deformation of short-fibre composites

A micromechanics model is proposed to analyse residual stresses and deformations that develop in short-fibre composites upon an applied uniform temperature change. The model is based on Eshelby's equivalent inclusion method and treats the interaction among fibres at finite volume fractions through the Mori-Tanaka mean field theory. The model treats the matrix as an elastic/plastic material while the fibre is elastic and is able to account for the effects of the composite microgeometry. To this end, the effects of misoriented short fibres, the orientation of which is described by a density distribution function, are considered. Numerical results obtained from the proposed model indicate that the misorientation of short fibres has a significant effect on both the stress and deformation behaviour of short-fibre composites.     

Production of hyaluronic‐acid‐based cell‐enclosing microparticles and microcapsules via enzymatic reaction using a microfluidic system

This article describes the preparation of cell‐enclosing hyaluronic acid (HA) microparticles with solid core and microcapsules with liquid core through cell‐friendly horseradish peroxidase (HRP)‐catalyzed hydrogelation. The spherical vehicles were made from HA derivative possessing phenolic hydroxyl moieties (HA‐Ph) cross‐linkable through the enzymatic reaction by extruding cell‐suspending HA‐Ph aqueous solution containing HRP from a needle of 180 μm in inner diameter into the ambient coaxial flow of liquid paraffin containing H₂O₂ in a microtubule of 600 μm in diameter. By altering the flow rate of liquid paraffin, the diameters of gelatin and HA‐Ph microparticles were varied in the range of 120–220 μm and 100–300 μm, respectively. The viability of the enclosed human hepatoma HepG2 cells in the HA‐Ph microparticles of 180 μm in diameter was 94.2 ± 2.3%. The growth of the enclosed HepG2 cells was enhanced by decreasing the HRP concentration. The microcapsules of 200 μm in diameter were obtained by extruding HA‐Ph aqueous solution containing thermally liquefiable cell‐enclosing gelatin microparticles of 150 μm in diameter using the same microfluidic system. The enclosed cells grew and filled the cavity within 10 days. Spherical tissues covered with a heterogeneous cell layer were obtained by degrading the microcapsule membrane using hyaluronidase after covering the surface with a heterogeneous cell layer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43107.     

Effects of reduction of the number of primordial follicles on follicular development to achieve puberty in female rats

Effects of reduction of the number of primordial follicles on follicular development and concentrations of circulating hormones were examined in immature female rat offspring of dams given busulfan intraperitoneally on day 14 of gestation. The offspring of dams treated with 5 mg busulfan kg(-1) showed vaginal opening at an age comparable with the offspring of dams treated with 2.5 mg busulfan kg(-1) or with corn oil as a control, although they exhibited an irregular oestrous cycle until week 14 after birth. The serum concentrations of immunoreactive inhibin and FSH on day 26 after birth of the offspring treated with 5 mg busulfan kg(-1) were similar to those of age-matched controls. On day 15 after birth, however, the concentration of their immunoreactive inhibin was markedly lower than that of controls, whereas the concentration of their FSH was increased inversely. Comparison of the numbers of ovarian follicles in the controls and groups treated with 2.5 mg busulfan kg(-1) and 5 mg busulfan kg(-1) revealed that prenatal treatment with busulfan reduced the number of follicles in the primordial or primary phase and in the preantral phase on day 7 after birth. Although the increase of the ratio of the number of preantral follicles during days 7-13 after birth tended to vary with the prenatal dose of busulfan, the number of preantral follicles in the group treated with 5 mg busulfan kg(-1) was still smaller than in the controls. The concentration of serum immunoreactive inhibin of the offspring treated with busulfan was reduced on day 7 after birth without alteration of the concentration of gonadotrophin. On day 13 after birth, the concentration of serum immunoreactive inhibin was reduced only in the offspring treated with 5 mg busulfan kg(-1), and the concentration of serum FSH of the offspring was increased inversely as found on day 15 after birth. These results indicate that a reduction in the number of primordial follicles decreases the number of follicles that enter the growing phase, a major source of circulating inhibin in the neonatal and infantile ovary, and that consequently increased circulating FSH may accelerate follicular development to achieve puberty.     

Growth and differentiation potentials in confluent state of culture of human skeletal muscle myoblasts

The transitional behaviors of myoblasts toward differentiation were investigated in the cultures at the low and high seeding densities (respectively, X₀ = 1.0 × 10³ and 2.0 × 10⁵ cells/cm²). In the culture at the low seeding density, an increase in confluence degree accompanied a decrease in growth potential (R_p), being R_p = 0.85 and 0.11 at t = 48 and 672 h, respectively. Myoblasts seeded at the high density resulted in the immediate cessation of growth with keeping the low range of R_p = 0.02–0.09 throughout the culture. The reduction of R_p led to the generation of three subpopulations of cells in proliferative, quiescent and differentiated states. Close cell contacts in the confluent state of high seeding culture induced cell quiescence to a higher extent with suppressing differentiation.     

Development and characterization of a photoautotrophic cell line of pak-bung hairy roots

A cell line of photoautotrophic pak-bung hairy roots was established from photomixotrophic ones by acclimation cultivations with a stepwise change of sucrose concentration in a medium with 3.0% CO2-enriched air supplied under continuous light irradiation. The derived photoautotrophic hairy roots had high chlorophyll content and activity of 1,5-ribulose-bisphosphate carboxylase/oxygenase, the values of which were 4.1- and 2.0-fold more than those of the parent photomixotroph, respectively. Electron microscopic observation revealed that the photoautotrophic hairy root cells possessed well-developed chloroplasts. The activities of ascorbate peroxidase and guaiacoal peroxidase found in the hairy roots were comparable to those found in the leaves and roots of parent plants of pak-bung, respectively. The elongation rate of growing points of the hairy roots was maximum at 5.0% CO2 concentration in gas phase and an incident light intensity of 10 W/m2 under the photoautotrophic conditions examined. Although light was indispensable for ensuring photoautotrophy of the hairy roots, it was found that exposure of the roots to strong light resulted in the reduction in the number of viable growing points governing the overall growth rate of the hairy roots.     

Photoautotrophic cultures of the host and transformed cells of Marchantia polymorpha under controlled incident light intensity

Photoautotrophic cultures of the host and transformed cells of the liverwort, Marchantia polymorpha, were examined. In cultures in flat glass flasks under various light intensities, it was found that the growth rates of both the cells increased with increase in light intensity in the range of 0 to 25 W/m2, but further increase in light intensity caused photoinhibition of the growth of the cells. Cultures of both the types of cells under light-controlled conditions using an externally illuminated bioreactor were carried out taking into consideration the inhibition of cell growth by excessive light and the light intensity distributions in the cell suspensions. In these cultures, 2.1 (transformed cells) and 3.3 (host cells) kg dry cell weight per m3 were harvested at culture times of 9.0 and 10 d, respectively. These values were larger than those obtained in cultures of the respective cells at a fixed incident light intensity of 25 W/m2.     

Dendrimer-immobilized culture surface as a tool to evaluate formation of cellular cytoskeleton of anchorage-dependent cells

Anchorage-dependent cultivation of human epithelial and keratinocyte cells was carried out on surfaces modified with synthesized dendrimers. Notable elongation of the epithelial cells was recognized on the culture surface immobilized with a dendrimer having D-glucose as a functional ligand, but not when a dendrimer having L-glucose was used or when the dendrimer was ligand-free. This morphological change was attributable to a temporary grasping of the cells at the D-glucose moiety via a glucose transporter-mediated mechanism present in the cell membrane. Following visualization of the actin filaments of the cells, it was considered that the cellular elongation on the D-glucose-bound dendrimer surface reflected the degree of formation of the cellular cytoskeleton. The cellular roundness was calculated by means of image analysis of the individual cells and employed as a parameter to evaluate the formation of the cellular cytoskeleton. In the culture of keratinocytes on the D-glucose-bound dendrimer surface, it was demonstrated that the decrease in the ratio of elongated cells (i.e., cells with a low roundness value) was correlated with the deterioration in the growth potential associated with cellular senescence.     

Electropolymerization kinetic study of 3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine and its optical optimization for electrochromic window applications

Poly (3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine), PProDOT-Me₂, is one of the most promising conducting polymers in the alkylenedioxythiophene based family for electrochromic window applications. In the electropolymerization kinetic study of 3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (ProDOT-Me₂), microgravimetry and chronoamperometry were used to determine the reaction orders with respect to the electrolyte and monomer, and the corresponding general kinetic equation of electropolymerization. This study presents that monomer concentration has a strong impact on electropolymerization mechanism. The relationship between film thickness and polymerization time was analyzed indicating that saturation of polymerization reduced the increase rate of film thickness with polymerization time. Also, the electropolymerization conditions were optimized to reach high contrast (Δ%T > 70%) with the minimum of transmittance (%T_min < 1) for electrochromic window applications.     

Evaluation of photo-induced cellular damage using photoautotrophic cultures of puk-bung hairy roots as a sensing tool

In photoautotrophic cultures of pak-bung hairy roots, strong light irradiation (22 W/m²) increased the content of reactive oxygen species (ROS) in the cells, resulting in chlorophyll (Chl) degradation and DNA injury. The Chl degradation rate, R_D, can be used as a parameter to measure the cellular damage caused by photo-induced stress. The presence of the antioxidants ascorbic acid, chlorogenic acid or catechin reduced the R_D, while lowering the content of ROS and moderating the DNA injury.     

Micro-temperature sensor array with thin-film thermocouples

A micro-temperature sensor array with thin-film thermocouples (TFTCs) is developed. The TFTCs are made with T-type (copper-constantan) thermocouples to measure chip temperature distribution of electronic packaging. The sensor array of 150 nm thickness has 10/spl times/10 junctions within a 9/spl times/9 mm area.