Effectiveness of Surface Texturing for Improving the Anti-seizure Property of Copper Alloy

AbstractIt is well known that lead-bronze is widely used in the automotive industry owing to the high anti-seizure property. However, because of toxicity of lead, the automotive industry demands a lead-free copper alloy from the viewpoint of environment. Lead- free copper alloy, which has the anti-seizure property as high as lead-bronze, has not been yet well exploited. For this reason, the objective of this study is to improve the anti-seizure property of lead-free copper alloy using a laser surface texturing (LST). In this study, a ring-on-ring sliding friction tester was used to assess the effectiveness of LST on the anti-seizure property of lead- free copper alloy. The upper specimens were made of FCD700, while the textured bottom specimens were made of PBC2 (lead- free copper alloy). A Daphne Hydraulic Fluid 32 (Idemitsu) paraffinic oil was used as a lubricant. The sliding friction test was conducted with a running-in period for 10min at a load of 50N. Afterwards, the load was increased incrementally from 50N to 1600N, while the friction coefficient was measured simultaneously. The friction test results showed that the textured specimens have a better anti-seizure property compared to the non-textured specimens. Based on the obtained experimental results, it was concluded that the arrangement and area ratio of dimples play an important role in improving the anti-seizure property

Lattice Anharmonicity in BiS2-Based Layered Superconductor RE(O,F)BiS2 (RE = La, Ce, Pr, Nd)

We studied Gr\"uneisen parameter ({\gamma}G) to investigate lattice anharmonicity in a layered BiS2-based superconductor system REO1-xFxBiS2 (RE = La, Ce, Pr, Nd), where in-plane chemical pressure was tuned by substituting the RE elements. With increasing in-plane chemical pressure, bulk modulus remarkably increases, and a high {\gamma}G is observed for RE = Nd. The dependence of {\gamma}G on in-plane chemical pressure exhibits a good correlation with Tc, and a higher Tc is achieved when {\gamma}G is large for RE = Nd. In addition, {\gamma}G shows a slight decrease by a decrease of F concentration (x) in REO1-xFxBiS2. Our results show that the anharmonic vibration of Bi along the c-axis is present in REO1-xFxBiS2, and the enhancement of the anharmonicity is positively linked to superconducting Tc and pairing mechanisms.Comment: 15 pages, 5 figure

Her yol Roma'ya varmaz!

Taha Toros Arşivi, Dosya Adı: Taha Torosİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Genetic Variability and Molecular Epidemiology of Respiratory Syncytial Virus Subgroup A Strains in Japan Determined by Heteroduplex Mobility Assay

We used heteroduplex mobility assay (HMA) to determine the genetic variability of 118 respiratory syncytial virus (RSV) field isolates from 19 epidemics occurring in a Japanese urban area between 1980 and 2000. Nucleotides 1 to 584 of the attachment G glycoprotein gene were amplified by reverse transcription-PCR, and the PCR amplicons were analyzed by HMA by using the earliest isolate from 1980 as the reference throughout. We also performed PCR-restriction fragment length polymorphism (RFLP) analysis and phylogenetic analysis on the same nucleotide sequence. PCR-RFLP revealed 9 patterns, whereas HMA produced 31 distinct patterns. The RFLP patterns were divided into two to seven distinct HMA genotypes. Field strains with similar degrees of G gene nucleotide differences from the reference strain often showed distinct HMA types. The RSV genetic heterogeneity detected by direct sequencing of the PCR amplicon was usually identical to HMA analysis. Analysis of the molecular epidemiology of RSV subgroup A isolates obtained by HMA showed that new RSV variants emerged with each epidemic and that previously dominant variants seldom recurred in subsequent epidemics. HMA is useful in detecting genetic variants of RSV subgroup A and has some advantages over other conventional methods

Tetrapyrrole signal as a cell-cycle coordinator from organelle to nuclear DNA replication in plant cells

Eukaryotic cells arose from an ancient endosymbiotic association of prokaryotes, with plant cells harboring 3 genomes as the remnants of such evolution. In plant cells, plastid and mitochondrial DNA replication [organelle DNA replication (ODR)] occurs in advance of the subsequent cell cycles composed of nuclear DNA replication (NDR) and cell division. However, the mechanism by which replication of these genomes with different origins is coordinated is largely unknown. Here, we show that NDR is regulated by a tetrapyrrole signal in plant cells, which has been suggested as an organelle-to-nucleus retrograde signal. In synchronized cultures of the primitive red alga Cyanidioschyzon merolae, specific inhibition of A-type cyclin-dependent kinase (CDKA) prevented NDR but not ODR after onset of the cell cycle. In contrast, inhibition of ODR by nalidixic acid also resulted in inhibition of NDR, indicating a strict dependence of NDR on ODR. The requirement of ODR for NDR was bypassed by addition of the tetrapyrrole intermediates protoporphyrin IX (ProtoIX) or Mg-ProtoIX, both of which activated CDKA without inducing ODR. This scheme was also observed in cultured tobacco cells (BY-2), where inhibition of ODR by nalidixic acid prevented CDKA activation and NDR, and these inhibitions were circumvented by Mg-ProtoIX without inducing ODR. We thus show that tetrapyrrole-mediated organelle–nucleus replicational coupling is an evolutionary conserved process among plant cells

Skull Bone Regeneration Using Chitosan–Siloxane Porous Hybrids—Long-Term Implantation

Burr holes in craniotomy are not self-repairing bone defects. To regenerate new bone at the sites of these defects, a good scaffold is required. Biodegradable hybrids including silica or siloxane networks have been investigated as bone tissue scaffolds. This study examined skull bone regeneration using chitosan-siloxane hybrids after long-term implantation (two and three years). After implantation of the hybrids, the surrounding cells migrated and formed fibrous tissues and blood vessels. Then, bone formation occurred from the surrounding blood vessels. Addition of calcium ions and coating with hydroxyapatite improved bone regeneration. Finally, the regenerated tissue area became smaller than the initial hole, and some areas changed to completed bone tissues