Solid-state synthesis and characterization of cobalt blue core-shell pigment particles

Cobalt blue is one of the most chemically and thermally stable blue pigments. However, cobalt is scarce and expensive. To minimize the use of cobalt and reduce production costs and toxicity, cobalt blue core-shell pigments were synthesized by a solid-state method, which is cheaper than a liquid-phase reaction. Small cobalt hydroxide particles and large α-alumina particles, in various ratios, were used as the starting materials. The dry mixed powders were calcined at 1200°C for 2 hours. Elemental mappings of the surfaces and cross sections of the synthesized particles showed that the cobalt blue had a core-shell structure. X-ray diffraction patterns showed that the synthesized cobalt blue consisted of an α-alumina core and a cobalt aluminate shell. The color tone of the synthesized cobalt blue was evaluated from the lightness (L*) and chroma (C*) values. The color tone of the cobalt blue synthesized in this study was almost same as those of commercially available samples although the cobalt molar fraction was lower than the stoichiometric ratio (Co/(Co + Al) = 0.33, Co/Al = 0.5) which was calculated from the chemical reaction formula.     

Hot topic: Pregnancy-induced expression of interferon-stimulated genes in the cervical and vaginal mucosal membranes

In ruminants, IFN-tau (IFNT) is a pregnancy recognition signal secreted by the embryonic trophectoderm before implantation, and it induces the expression of IFN-stimulated genes (ISG) in the uterine endometrium and blood leukocytes. The expression of ISG in blood leukocytes could indicate the presence of a viable conceptus before return of the next estrus; however, expression levels have high variation for confirming pregnancy. We hypothesized that the secreted IFNT in the uterus would affect ISG expression in cervical and vaginal tissues because they are directly adjacent to the uterus. To prove the hypothesis, we investigated the expression of 3 ISG (ISG15, MX1, and MX2) in cervical and vaginal mucosal membranes collected from pregnant (n = 12) and nonpregnant (n = 11) lactating Holstein cows at 17 to 18 d after artificial insemination. Mucosal membrane samples of the cervical canal near the external os (cervix) and deep vaginal wall surrounding the external os (vagina) were collected separately by simply scraping with a curette on d 17 or 18 of pregnancy (d 1 = ovulation), at which time IFNT secretion into the maternal uterus is maximal. After pregnancy diagnosis on d 30 and 60, separately collected samples confirmed as pregnant and nonpregnant were used for evaluation of the expression of IFN-stimulated protein 15 kDa (ISG15) and myxovirus-resistance protein 1 and 2 (MX1, MX2) with quantitative real-time PCR. The collected mucosal membrane samples from cervix contained mostly cell clots showing membrane structure and a low content of blood cells. The expression levels of all 3 genes were significantly increased in pregnant cows compared with nonpregnant cows in both cervical and vaginal samples. These results suggest that increased expression of ISG in the cervix and vagina is a pregnancy-associated phenomenon and is highly affected by IFNT secreted from the conceptus through the uterus.     

RNA‐Capturing Microsphere Particles (R‐CAMPs) for Optimization of Functional Aptamers

RNA aptamers are useful building blocks for constructing functional nucleic acid‐based nanoarchitectures. The abilities of aptamers to recognize specific ligands have also been utilized for various biotechnological applications. Solution conditions, which can differ depending on the application, impact the affinity of the aptamers, and thus it is important to optimize the aptamers for the solution conditions to be employed. To simplify the aptamer optimization process, an efficient method that enables re‐selection of an aptamer from a partially randomized library is developed. The process relies on RNA‐capturing microsphere particles (R‐CAMPs): each particle displays different clones of identical DNA and RNA sequences. Using a fluorescence‐activated cell sorter, the R‐CAMPs that are linked to functional aptamers are sorted. It is demonstrated that after a single round of reselection, several functional aptamers, including the wild‐type, are selected from a library of 16 384 sequences. The selection using R‐CAMPs is further performed under the solution containing high concentration of ethylene glycol, suggesting applicability in various conditions to optimize an aptamer for a particular application. As any type of RNA clone can be displayed on the microspheres, the technology demonstrated here will be useful for the selection of RNAs based on diverse functions.     

Online mathematics education as bio-eco-techno process: bibliometric analysis using co-authorship and bibliographic coupling

Scientometrics - Under the COVID-19 pandemic, mathematics education has moved completely online. To tackle this new norm based on bio-eco-techno theories, this study aims to provide educators an...     

Control of microbial adhesion using fine particle technology

Microbial adhesion to an interface plays an important role in many industrial bioengineering processes. Surface physicochemical properties can be treated as an indicator of the adhesive properties of microbial cells. In this paper, the application of the aggregation/dispersion technique used in fine particle technology to biotechnology is reviewed. By way of illustration, measurements of the surface characteristics of microbes living in an anaerobic digester, analysis of microbial adhesion and aggregation/coaggregation, and their application are introduced.     

Mechanics of peristaltic locomotion and role of anchoring

Limbless crawling is a fundamental form of biological locomotion adopted by a wide variety of species, including the amoeba, earthworm and snake. An interesting question from a biomechanics perspective is how limbless crawlers control their flexible bodies in order to realize directional migration. In this paper, we discuss the simple but instructive problem of peristalsis-like locomotion driven by elongation–contraction waves that propagate along the body axis, a process frequently observed in slender species such as the earthworm. We show that the basic equation describing this type of locomotion is a linear, one-dimensional diffusion equation with a time–space-dependent diffusion coefficient and a source term, both of which express the biological action that drives the locomotion. A perturbation analysis of the equation reveals that adequate control of friction with the substrate on which locomotion occurs is indispensable in order to translate the internal motion (propagation of the elongation–contraction wave) into directional migration. Both the locomotion speed and its direction (relative to the wave propagation) can be changed by the control of friction. The biological relevance of this mechanism is discussed.     

Enhanced high-temperature strength of HfB2–SiC composite up to 1600°C

Using B₄C and C additives, a HfB₂–SiC composite with an enhanced strength up to 1600?°C was prepared using high-energy ball milling followed by hot pressing. The composite microstructure comprised equiaxed large HfB₂ and fine SiC grains and an intergranular amorphous phase. The mechanical behaviour of the composite was evaluated up to 1600?°C via a four-point bending test. At or below 1500?°C, only a linear stress–strain response was observed. At 1600?°C, however, the initial linear response was followed by nonlinear deformation behaviour. The flexural strength was constant between room temperature and 1400?°C; subsequently, the flexural strength significantly increased with increasing temperature up to 1600?°C, with strengths in the range of 650–750?MPa.