Reaction of calcium and phosphate ions with titanium,zirconium, niobium,and tantalum

To understand the bone formation ability of constituent metal elements of new titanium alloys, titanium, zirconium, niobium, and tantalum, these metals were immersed in various electrolytes containing calcium and/or phosphate ions and characterized using X‐ray photoelectron spectroscopy. In addition, cathodic polarization of the metals in the electrolytes was performed to evaluate the stability of the surface oxide films on the metals in the electrolyte. The calcium phosphate layer formed on Ti in electrolytes containing calcium and phosphate ions is relatively protective against mass transfer throughout the layer. However, the zirconium phosphate layer formed on Zr is much more protective and stable than that on Ti. Therefore, calcium ions were not incorporated. Nb and Ta formed calcium phosphate, but the amount was smaller than that in Ti, because phosphates formed on Nb and Ta are somewhat protective and the incorporation of the calcium ion is inhibited. Titanium played the most important role in forming calcium phosphate, while zirconium inhibited the formation of calcium phosphate on titanium alloys. The control of bone formation is feasible by the design of titanium alloys. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and development of biologically active fluorescent-labeled vitamin K analogues and monitoring of their subcellular distribution

New fluorescent analogues of menaquinone-4 and phylloquinone were prepared and their subcellular distribution monitored using a confocal laser scanning microscope. These analogues incorporate an FITC group anchored to the naphthoquinone skeleton through an amide bond expected to be resistant to metabolism. On their addition to the culture medium, fluorescence was readily observed inside a human osteosarcoma cell line. This result indicates that the fluorescent analogues penetrate into cells the same as vitamin K, and therefore, would be useful for achieving insight into the action mechanism of vitamin K.     

Asymmetric anionic polymerization of N‐1‐naphthylmaleimide with chiral ligand‐organometal complexes in toluene

Asymmetric anionic homopolymerizations of N‐1‐naphthylmaleimide (1‐NMI) were performed with chiral ligand/organometal complexes to form optically active polymers. Poly(1‐NMI)s obtained with methylene‐bridged bisoxazoline derivatives (Rbox)‐diethylzinc (Et₂Zn) complexes showed high specific optical rotations ([α]) from +152.3 to +191.4°. Circular dichroism spectra of the polymers exhibited a split Cotton effect in the UV absorption‐band region. According to the exciton chirality method, the absolute configuration of the polymer main chain was determined according to the following method: (+)‐poly[N‐substituted maleimides (RMI)] main chains can contain more (S,S)‐ than (R,R)‐configurations. (?)‐Poly(RMI) main chains can contain more (R,R)‐ than (S,S)‐configurations. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3556–3565, 2001     

Synthesis and properties of aramids and polyarylates having perfluoro-substituents on the benzene ring

A new series of 16 aramids and 16 polyarylates having perfluoro-substituents on the benzene ring was prepared by a low temperature solution or an interfacial polycondensation. The effects of fluorine substituents on the structure and properties of polymers were examined. Fluorinated aramids exhibited higher crystallinity, while fluorinated polyarylates show lower crystallinity. The melting point (T_m) of aramids decreased with fluorine substitution, whereas T_m of polyarylates from fluorinated aromatic diols was higher than that of those from unfluorinated ones. The temperature of 10% weight loss and the residue at 900°C decreased with fluorine substitution except for the aramids from fluorinated diamines. Solubility and contact angle also increased with fluorine substitution. Some polyarylates were found to exhibit an optical anisotropy.     

Application of ion-exchange cartridge clean-up in food analysis I. Simultaneous determination of thiabendazole and imazalil in citrus fruit and banana using high-performance liquid chromatography with ultraviolet detection

A simple, rapid and reproducible analytical method for thiabendazole (TBZ) and imazalil (IMA) in citrus fruit and banana has been developed. The method involves the use of an ion-exchange cartridge for sample clean-up followed by ion-pair high-performance liquid chromatography with ultraviolet detection. The recoveries of TBZ and IMA from citrus fruits spiked at levels of 10 μg/g and 5 μg/g were in the range of 94–98% and 93–98% with coefficients of variation of 0.5–2.2% and 1.6–2.7%, respectively. The recoveries of TBZ and IMA from banana spiked at levels of 3 μg/g and 2 μg/g were 94% and 94% with coefficients of variation 1.1% and 4.9%, respectively. The detection limits for TBZ and IMA were 0.1 μg/g in citrus fruit and 0.05 μg/g in banana.     

Studies of surface modification of solids

The surface of silica was treated with trimethylchlorosilane (TMCS) and hexa-methyldisilazane (HMDS) respectively and the immersional heat into water, adsorption capacity for water vapor and infrared absorption spectra were measured. TMCS reacts with freely vibrating silanols while HMDS also reacts with other silanols. By treatment with silane, the silica surface is covered by the trimethylsilyl group, a maximum amount of which attains 1 meq/g (3 groups/nm²). As the amount of the trimethylsilyl group on silica increases, the immersional heat of silica into water decreases and attains a constant value of about 25 erg/cm², which is the typcial value for a hydrophobic surface. The interaction of the trimethylsilyl group with water is weak, therefore the adsorptive capacity for water vapor is lessened remarkably by treatment with silane.     

Asymmetric polymerization of N‐substituted maleimides with chiral oxazolidine–organolithium

Asymmetric anionic homopolymerizations of achiral N‐substituted maleimides (RMI) were performed with lithium 4‐alkyl‐2,2‐dialkyloxazolidinylamide. All obtained polymers were optically active, exhibiting opposite optical rotation to that of a corresponding oxazolidinyl group at the terminal of the main chain. This suggests that opposite optical rotation to the corresponding chiral oxazolidine was induced to the polymer main chain. In the polymerization using a fluorenyllithium (FlLi)–oxazolidine complex, the obtained polymer with a fluorenyl group at the polymer end showed a negative specific rotation. This also suggests that asymmetric induction took place in the polymer main chain. The asymmetric induction was supported by the circular dichroism (CD) and GPC analysis with polarimetric detector. Optical activity of the polymer was attributed to different contents of (S,S) and (R,R) structures formed from threo‐diisotactic additions, as supported by the ¹³C‐NMR spectra of the polymers and the model compounds. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 473–482, 1999     

Hydrostatic Extrusion of Poly(L-Lactide)

Poly-L-Lactide(PLLA) has been used as a bone fracture fixation material for several years. However, its mechanical properties are still not satisfied. To improve its mechanical properties, we examined the hydrostatic extrusion procedure on the PLLA rods made by Injection Molding process. The extrusion ratio was adjusted to 3, 6, 9, and 12. The molecular weight of the PLLA decreased from 260,000 to 200,000 after injection molding process, but it did not change during the hydrostatic extrusion procedure. The melting point of PLLA hydrostatic extrusion products were increased with the extrusion ratio, but the increment was not obviouse. Extrusion products having low extrusion ratio had α-form crystal in them, extrusion products having high extrusion ratio had both of α and β-form crystall in them. At extrusion temperature of 145°C, PLLA rods showed the best flowing trends in the pressure medium of PEG 400. Extrusion temperature is placed in the range of crystalline transition temperature and melting point of PLLA. At extrusion ratio 9∼12, the extrusion products showed the best mechanical properties. The highest bending strength of the extrusion product was over than 350MPa. It is far stronger than that of the human cortical bone (200MPa). SEM observations showed that the fiber structure began to appear at an extrusion ratio ER=3, and at the extrusion ratio ER=6, the chain axes of PLLA became aligned to the extrusion direction. The structure of extrusion products at the high extrusion ratio showed highly oriented fiber structure composed of micro-fibril. At high extrusion ratio tranformation from α-crystal to β-crystal was also observed.     

Variation of the Alexander-Conway polynomial under Dehn surgery

Let ε₁ and ε₂ belong to {±1}. When the ε₁-surgery along a knot K₁ in S³ produces the same homology sphere as the ε₂-surgery along a knot K₂ in S³, then the Casson surgery formula implies that ε₁Δ_K1″(1)=ε₂Δ_K2″(1), where Δ(t) denotes the symmetric Alexander polynomial. For any pair (Λ₁(t),Λ₂(t)) of possible knot Alexander polynomials such that ε₁Λ₁″(1)=ε₂Λ₂″(1), we exhibit a pair (K₁,K₂) of knots in S³ such that Δ_K1(t)=Λ₁(t), Δ_K2(t)=Λ₂(t) and the ε₁-surgery along K₁ produces the same homology sphere as the ε₂-surgery along K₂.