Characteristics of trypsin from the pyloric ceca of walleye pollock (Theragra chalcogramma)

Trypsin was purified from the pyloric ceca of walleye pollock (Theragra chalcogramma) by gel filtration on Sephacryl S-200 and Sephadex G-50. The final enzyme preparation was nearly homogeneous in sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and the molecular mass of the enzyme was estimated to be 24 kDa by SDS–PAGE. Trypsin activity was effectively inhibited by serine protease inhibitors, such as soybean trypsin inhibitor and TLCK. Trypsin had maximal activities at around pH 8.0 and 50 °C for the hydrolysis of N^α-p-tosyl-l-arginine methyl ester hydrochloride. Trypsin was unstable above 30 °C and below pH 5.0, and was stabilized by calcium ions. Walleye pollock trypsin was more thermally unstable than trypsin from the Temperate Zone fish and Tropical Zone fish. The N-terminal amino acid sequence of the trypsin, IVGGYECTKHSQAHQVSLNS, was found, and the sequential identity between the walleye pollock trypsin and Frigid Zone fish trypsin was higher (85–100%) than with Temperate Zone fish trypsin (75–90%), Tropical Zone fish trypsin (75–85%), or mammalian trypsin (60–65%).     

纳米金属微粒催化制备的洋葱状富勒烯的结构表征

采用金属Cu，Al做粒／石墨混合材料．用直流电弧放电方法制备了洋葱状富勒烯。对两种产物进行了XRD、SEM、HRTEM和Raman结构表征。结果表明：两种纳米金属微粒均可催化得到洋葱状富勒烯；所得产物中有单纯洋葱状富勒烯和内包纳米金属微粒洋葱状富勒烯，且石墨化程度都很高；纳米金属微粒尺寸大小不同决定洋葱状富勒烯的直径分布不均匀，从而造成其拉曼谱峰相对于石墨特征峰1582cm^-1发生了频移；用汽-液-固(VLS)生长模型描述了洋葱状富勒烯生长机理，解释了汽态碳原子通过在液态催化剂中扩散和析出，逐渐长大成形的现象。     

Synthesis of perovskite-type (La1−xCax)FeO3 (0 ≤ x ≤ 0.2) at low temperature

Gel formation was realized by adding citric acid to a solution of La(NO₃)₃·5H₂O, Ca(NO₃)₂·4H₂O, and Fe(NO₃)₂·9H₂O. Perovskite-type (La_1−xCa_x)FeO₃ (0 ≤ x ≤ 0.2) was synthesized by firing the gel at 500 °C in air for 1 h. The crystallite size (D_1 2 1) decreased with increasing x, while the specific surface area was 6.8-9.4 m²/g and independent of x. The XPS measurement of the (La_1−xCa_x)FeO₃ surface indicated that the Ca²⁺ ion content increased with increasing x, while the Fe ion content was independent of x. Catalytic activity for CO oxidation increased with increasing x.     

Expression of leukaemia inhibitory factor (LIF) receptor in human placenta: a possible role for LIF in the growth and differentiation of trophoblasts

Leukaemia inhibitory factor (LIF) is a cytokine that displays multiple activities in various tissues and is essential for blastocyst implantation in mice. In the human uterus, LIF is expressed in endometrial tissue and the decidua. To elucidate the role it plays, the mRNA levels for two LIF receptor (R) subunits, LIF-R and gp130, were examined in human endometrium, placenta and decidua by Northern blot hybridization. The expression of LIF-R gene was detected in the chorionic villus during the first trimester, in term placenta, and at lower levels in the decidua. The expression of LIF-R gene was not detectable in non-pregnant endometrium. The expression of the gp130 gene was detected in all tissues examined. During pregnancy, there was no significant change in the mRNA concentration of LIF-R in the placenta, while that of gp130 increased after the second trimester. The human choriocarcinoma cell line, BeWo, was found to express LIF-R and gp130. LIF inhibited forskolin-induced human chorionic gonadotrophin (HCG)-beta production by BeWo in a dose-dependent manner, and it ameliorated forskolin-induced growth suppression. These findings suggest that LIF plays a regulatory role in trophoblast growth and differentiation during pregnancy in human placenta.     

Synthesis of the Right-Side Structure of Type B Physalins

We present a full account of our synthetic studies on the racemic DEFGH-ring moiety of physalins, featuring domino ring transformation of a tricyclic key intermediate. We also report the results of a detailed mechanistic examination of the domino ring transformation, as well as a reoptimization of the 2,3-Wittig rearrangement and methylation steps. Furthermore, we have newly established a method for the preparation of an optically active synthetic intermediate by enzymatic kinetic resolution. Our work provides access to both natural and nonnatural right-side physalin structures.     

Gray and grayness—its complexities in color appearance of surface colors

Complexities on the roles of reference color gray and grayness are reviewed. They are essential in color appearance, but gray is an implicit color. Although “grayness” is not explicitly used in visual color assessment of surface colors or color order systems, gray can be combined with any colors having six primary‐color components using the term “grayish,” for example, grayish red and grayish yellow. However, the existing region of grayness is limited in a part of color‐appearance space. Illuminance dependency of gray perception is also clarified. Existence of two kinds of psychometric quantities are suggested: one is the attribute of grayness based on its psychological amount in a grayish color under study, and the other is the attribute of brightness of the grayish color under a specified illuminance, psychophysical quantity. The Nayatani‐Theoretical color order system, which uses three opponent‐colors axes, can clarify the above complexities of gray and grayness. Its importance is the same as six primary colors, red–green, yellow–blue, and white–black. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 37–44, 2014     

Generation of multihollow structured poly(methyl methacrylate) fibers by electrospinning under pressurized CO2

Electrospinning is one of the simple techniques for the production of polymer nano‐microfibers. In this study, hollow fibers from poly(methyl methacrylate) (PMMA) were formed by electrospinning under pressurized carbon dioxide (CO₂) in a single processing step. The experiments were conducted at temperatures and pressures in the range 27–37°C and 4–6 MPa, respectively. At 5 MPa, CO₂ seemed to have enough affinity to dissolve a portion of dichloromethane (DCM) to assist its evaporation. Under subcritical CO₂, electrospun products with hollow core fibers having diameters of 4–16 μm were generated. The results confirmed that the change of operating parameters had a strong influence on the morphologies (crack or hollows) of the electrospun products. This study demonstrated that this process offers the possibility that electrospinning under pressurized CO₂ will become an essential and useful method for the generation of polymer structures with hollow interiors. POLYM. ENG. SCI., 56:752–759, 2016. © 2016 Society of Plastics Engineers     

Modified Gronwall's inequality and its application to stabilization problem for semilinear parabolic systems

This paper deals with the stabilization of semilinear parabolic distributed systems by means of boundary controls. The partial differential equation describing the system is formulated as a semilinear evolution equation in a Hilbert space by using a variable transformation. Here it is shown that the solution globally exists for the closed-loop system which installs a finite-dimensional dynamic compensator by using the properties of an analytic semigroup. Moreover, a sufficient condition for stabilization of the system is derived by making use of the modified Gronwall's inequality developed in this paper.     

Probing the Nature and the Structure of Pores in Silica Xerogels by Water Sorption: The Tetramethyl Orthosilicate-Hydrogen Chloride/Fluoride System

A series of silica xerogels were synthesized in a closed system by hydrolyzing tetramethyl orthosilicate (TMOS) with various concentrations of hydrochloric acid solution but without the addition of alcohol. The molar ratio of H₂O to TMOS was fixed at 4.96. The gels were characterized by water and nitrogen sorption measurements. The gelation time peaked at 50 to 80 h with 5 × 10⁻² to 10⁻¹ M HCl, apparently a consequence of the isoelectric point of silica. Surface area, pore size, and sorption capacity were, however, at a minimum for samples prepared with 5 × 10⁻² to 10⁻¹ M HCl. The BET c constant and hence the net heats of sorption were at a maximum for these samples. Although water sorption of all the samples prepared with HCl exhibited moderate Type I isotherms, the concavity of the isotherms to the P/P ₀ axis increased with increasing concentrations of HCl up to 10⁻¹ M in accordance with the decreased pore size and increased heat of sorption. Addition of F⁻ ions (HF or NaF) in the presence of 10⁻¹ M HCl steadily decreased the gelation time. Addition of F⁻ in the absence of HCl, however, caused rapid gelation and an increase in pore size, nitrogen BET surface area, and hydrophobicity. Consequently, the shape of water isotherms gradually converted to Type IV and/or Type V. Adsorption and desorption measurements on differently activated gels exhibited various types of hystereses as a result of development of hydrophobie sites at as low as 200°C, inelastic distortion induced by adsorption, and chemical reaction and aging of gels when exposed to water vapor.