Titanium-Based Biomaterials for Preventing Stress Shielding between Implant Devices and Bone

β-type titanium alloys with low Young's modulus are required to inhibit bone atrophy and enhance bone remodeling for implants used to substitute failed hard tissue. At the same time, these titanium alloys are required to have high static and dynamic strength. On the other hand, metallic biomaterials with variable Young's modulus are required to satisfy the needs of both patients and surgeons, namely, low and high Young's moduli, respectively. In this paper, we have discussed effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications. Then, the advantage of low Young's modulus of β-type titanium alloys in biomedical applications has been discussed from the perspective of inhibiting bone atrophy and enhancing bone remodeling. Further, we have discussed the development of β-type titanium alloys with a self-adjusting Young's modulus for use in removable implants

Adversarial guesswork with quantum side information

The guesswork of a classical-quantum channel quantifies the cost incurred in guessing the state transmitted by the channel when only one state can be queried at a time, maximized over any classical pre-processing and minimized over any quantum post-processing. For arbitrary-dimensional covariant classical-quantum channels, we prove the invariance of the optimal pre-processing and the covariance of the optimal post-processing. In the qubit case, we compute the optimal guesswork for the class of so-called highly symmetric informationally complete classical-quantum channels.Comment: 7 page

Molecular phylogenetic analyses reveal a close evolutionary relationship between Podosphaera (Erysiphales: Erysiphaceae) and its rosaceous hosts

Podosphaera is a genus of the powdery mildew fungi belonging to the tribe Cystotheceae of the Erysiphaceae. Among the host plants of Podosphaera, 86 % of hosts of the section Podosphaera and 57 % hosts of the subsection Sphaerotheca belong to the Rosaceae. In order to reconstruct the phylogeny of Podosphaera and to determine evolutionary relationships between Podosphaera and its host plants, we used 152 ITS sequences and 69 28S rDNA sequences of Podosphaera for phylogenetic analyses. As a result, Podosphaera was divided into two large clades: clade 1, consisting of the section Podosphaera on Prunus (P. tridactyla s.l.) and subsection Magnicellulatae; and clade 2, composed of the remaining member of section Podosphaera and subsection Sphaerotheca. Because section Podosphaera takes a basal position in both clades, section Podosphaera may be ancestral in the genus Podosphaera, and the subsections Sphaerotheca and Magnicellulatae may have evolved from section Podosphaera independently. Podosphaera isolates from the respective subfamilies of Rosaceae each formed different groups in the trees, suggesting a close evolutionary relationship between Podosphaera spp. and their rosaceous hosts. However, tree topology comparison and molecular clock calibration did not support the possibility of co-speciation between Podosphaera and Rosaceae. Molecular phylogeny did not support species delimitation of P. aphanis, P. clandestina, P. ferruginea, P. spiraeae and P. tridactyla in their current circumscriptions, which suggests the need for revision of these species

Corrosion Behaviour of Titanium β Type Ti-12Cr in 3% NaCl Solution

Titanium alloy, especially titanium type Ti-12Cr for biomedical application has been a concern of many researchers recently. This titanium has excellent biocompatibility and controllable mechanical properties. Generally, titanium β type contains many alloying elements that lead to a high price. Therefore, it is interesting to develop β type with only one cheap alloying element such as Ti-12Cr that is designed as a low-cost implant material. Initially, Ti-12Cr has been developed, in particular for spinal fixation. Nowadays, the research of Ti-12Cr emphasizes only on mechanical properties. The corrosion behavior of this alloy has not been understood well yet. Therefore, corrosion characteristics of this alloy in any circumstances are necessary to investigate. This paper reports the corrosion behavior of Ti-12Cr in a salted environment using the weight loss method. Ti-12Cr samples were immersed in a 3% NaCl solution for 2, 4, and 6 weeks. Samples consist of Ti-12Cr (as-received), Ti-12Cr (ST) and Ti-12Cr (AT 30 ks). Weight of samples was measured before and after the immersing process using the digital balance. Microstructure and composition of the sample surfaces were examined by using SEM and EDX, respectively. The lowest corrosion rate after exposure for 6 weeks while the highest one is Ti-12Cr (as-received) is Ti-12Cr (AT 30 ks) that is 0,003 mmpy. The microstructure all of the samples shows black spots in the surfaces indicating corrosion has been started to occur on the samples. It  was found that the corrosion is due to destruction of the chrome-oxide layer in some weak point as a result of a chemical reaction between the metal (Cr) with Cl- ions. Some oxides are formed on the surface of titanium, as indicated by a significant increment of oxygen content is the corrosive sample surface. This study indicates the corrosion resistance of Ti-12Cr (AT 30 ks) is much better than other materials in this research.