Tkachenko waves, glitches and precession in neutron star

Here I discuss possible relations between free precession of neutron stars, Tkachenko waves inside them and glitches. I note that the proposed precession period of the isolated neutron star RX J0720.4-3125 (Haberl et al. 2006) is consistent with the period of Tkachenko waves for the spin period 8.4s. Based on a possible observation of a glitch in RX J0720.4-3125 (van Kerkwijk et al. 2007), I propose a simple model, in which long period precession is powered by Tkachenko waves generated by a glitch. The period of free precession, determined by a NS oblateness, should be equal to the standing Tkachenko wave period for effective energy transfer from the standing wave to the precession motion. A similar scenario can be applicable also in the case of the PSR B1828-11.Comment: 6 pages, no figures, accepted to Ap&S

Magnetic Field Generation in Stars

Enormous progress has been made on observing stellar magnetism in stars from the main sequence through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which remains one of the main unanswered questions in astrophysics. In this chapter we review recent work in this area of research. In particular, we look at the fossil field hypothesis which links magnetism in compact stars to magnetism in main sequence and pre-main sequence stars and we consider why its feasibility has now been questioned particularly in the context of highly magnetic white dwarfs. We also review the fossil versus dynamo debate in the context of neutron stars and the roles played by key physical processes such as buoyancy, helicity, and superfluid turbulence,in the generation and stability of neutron star fields. Independent information on the internal magnetic field of neutron stars will come from future gravitational wave detections. Thus we maybe at the dawn of a new era of exciting discoveries in compact star magnetism driven by the opening of a new, non-electromagnetic observational window. We also review recent advances in the theory and computation of magnetohydrodynamic turbulence as it applies to stellar magnetism and dynamo theory. These advances offer insight into the action of stellar dynamos as well as processes whichcontrol the diffusive magnetic flux transport in stars.Comment: 41 pages, 7 figures. Invited review chapter on on magnetic field generation in stars to appear in Space Science Reviews, Springe

Astragaloside IV and cycloastragenol production in in vitro produced Astragalus trojanus Stev.

In the present paper, an efficient method for clonal propagation of an endemic plant, Astragalus trojanus Stev., was described. Effect of sucrose and 6-benzyladenine (BA) concentrations on shoot proliferation and rooting was studied. Woody plant medium (WPM) supplemented with two different concentrations of BA (S1 medium with 0.5 mg/L BA&S2 medium with 1 mg/L BA) was used, where S2 medium resulted in higher rates in both shoot elongation and multiple shoot proliferation of clonally propagated A. trojanus shoot cultures. Of 27 clones, 3 were selected for further studies based on the highest regeneration capacity (Clones 1, 12&15). A total of 340 shoots were obtained from Clone 1 in S1 medium. In this medium, the rooting ratio of shoots for Clone 15 was 11.67%. The highest shoot elongation (1.99 cm), multiple shoot proliferation ratio (4.35) and multiple shoot proliferation percentage (91.67%) were obtained from Clone 1 in S2 medium. Two media, WPM medium supplemented with 15 g/L (K1 medium) and 30 g/L (K2 medium) sucrose were used for rooting. The root formation of Clone 1 was 26.67% in K2 medium. The highest astragaloside IV (0.5486 µg/mg) and cycloastragenol (0.1263 µg/mg) contents were detected in roots grown in K1 medium

Biomimetic peptide-conjugated membranes for developing an artificial cornea

2022 Medical Technologies Congress, TIPTEKNO 2022 -- 31 October 2022 through 2 November 2022 -- -- 184752The corneal endothelium is composed of a single layer of specialized endothelial cells, protecting, and nourishing the inner surface of the cornea. Corneal endothelial cells do not proliferate after birth and their number decrease with age. Trauma, inflammation, or surgical intervention can cause cell loss. When damage is extensive and the density of corneal endothelial cells decreases to a critical level, it results in corneal edema and vision loss. Besides them, when corneal endothelium has irreversible damage, the only treatment way is corneal transplantation. But there are some drawbacks such as finding donors, immune reactions, and the number of patients waiting on the transplantation lists for years. Tissue engineering approaches can provide promising alternatives for the regeneration of corneal endothelium tissue. Peptides can be used to modify and functionalize the scaffolds, allowing for the production of bioactive and biomimetic surfaces. Peptide-modified scaffold surfaces might direct and enhance the behaviors of cells. In this study, the aim was to functionalize the polycaprolactone (PCL) membranes with tissue-specific peptides and to characterize the peptide-conjugated membranes by Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Photoelectron Spectroscopy (XPS) analysis. The synthesized peptides were successfully conjugated on the PCL biomembranes. © 2022 IEEE.ACKNOWLEDGMENT The authors thank to the Scientific and Technological Research Council of Turkey (TUBITAK) (1003 Project numbers: 218S991, 219S989, and 318S275).Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK: 218S991, 219S989, 318S27

Cycloartane-type sapogenol derivatives inhibit NF?B activation as chemopreventive strategy for inflammation-induced prostate carcinogenesis

PubMed ID: 29678446Chronic inflammation is associated to 25% of cancer cases according to epidemiological data. Therefore, inhibition of inflammation-induced carcinogenesis can be an efficient therapeutic approach for cancer chemoprevention in drug development studies. It is also determined that anti-inflammatory drugs reduce cancer incidence. Cell culture-based in vitro screening methods are used as a fast and efficient method to investigate the biological activities of the biomolecules. In addition, saponins are molecules that are isolated from natural sources and are known to have potential for tumor inhibition. Studies on the preparation of analogues of cycloartane-type sapogenols (9,19-cyclolanostanes) have so far been limited. Therefore we have decided to direct our efforts toward the exploration of new anti-tumor agents prepared from cycloastragenol and its production artifact astragenol. The semi-synthetic derivatives were prepared mainly by oxidation, condensation, alkylation, acylation, and elimination reactions. After preliminary studies, five sapogenol analogues, two of which were new compounds (2 and 3), were selected and screened for their inhibitory activity on cell viability and NF?B signaling pathway activity in LNCaP prostate cancer cells. We found that the astragenol derivatives 1 and 2 as well as cycloastragenol derivatives 3, 4, and 5 exhibited strong inhibitory activity on NF?B signaling leading the repression of NF?B transcriptional activation and suppressed cell proliferation. The results suggested that these molecules might have significant potential for chemoprevention of prostate carcinogenesis induced by inflammatory NF?B signaling pathway. © 2018 Elsevier Inc.113Z078This work was supported by Turkish Scientific and Technological Research Council (TUBITAK) with the project number 113Z078 to BDB. Appendix A -