Ultimate speed of the supercurrent and its pairing mechanism

Recently, the room-temperature superconductor (RTSC) was discovered as a two-dimensional (2D) square lattice made of a metal wherein positive charges, i.e. holes, were heavily concentrated. The experimental result for the critical magnetic field $H_{c}$ was fully consistent with the view on the RTSC that its lattice unit -- a metal island -- is filled with the Slater's atoms. Each Slater's atom has the expanded diameter of 14.5 nm in order to have perfect diamagnetism with the magnitude corresponding to a single flux quantum $\phi_{0}$. Its expanded orbit is associated with the fine structure constant $\alpha \approx \frac{1}{137}$. In this paper, another important critical value -- the critical current $I_{c}$ -- is reported. It was found that the supercurrent has achieved the ultimate speed of matter, i.e., the speed of light, $c$. Beginning with a warm-up exercise for the Bohr's atom, how the Slater's atom is formed and why the $c$ appears are shown. These considerations lead to a simple view on the pairing mechanism of superconductivity, which also gives an ample indication of the most mysterious physical number $\alpha$. Finally, it is shown that the proposed pairing mechanism in terms of London's canonical momentum naturally generates the perfect diamagnetic $\phi_{0}$ of the Slater's atom, and the superconducting energy gap $\Delta$ is predicted.Comment: 13 pages, 4 figures + appendi

Possible room temperature superconductivity in an Nb holey sheet as a result of a first order phase transition

By drilling periodic thru-holes in a suspended film, the phonon system can be modified. Motivated by the BCS theory, the technique -- so-called phonon engineering -- was applied to a niobium (Nb) sheet. It was found that during a cooling cycle its electrical resistance dropped to zero at 175 K. More unexpectedly, during the subsequent warming cycle, the zero-resistance state persisted up to 290 K. Neither these high-temperature transitions nor the irreversibility can be accounted for by the BCS theory. Yet the extraordinary phenomenon was reproduced many times, therefore, there must be a new physics or superconductivity as the solid foundation of these phenomena. In addition to the electrical results, this study reports magnetic results such as magnetization drop and flux trapping at 300 K. Another experimental fact that the metallic holey sheet is partly oxidized to form a niobium-oxygen square lattice is also remarkable since it has points of resemblance to a copper-oxygen plane, the fundamental component of cuprate high-$T_{c}$ superconductors.Comment: 12 pages, 8 figures, and Supplementary material. arXiv admin note: substantial text overlap with arXiv:2209.0316

Astrophysical Condition on the attolensing as a possible probe for a modified gravity theory

We investigate the wave effect in the gravitational lensing by a black hole with very tiny mass less than 10^-19 solar mass, which is called attolensing, motivated by a recent report that the lensing signature might be a possible probe of a modified gravity theory in the braneworld scenario. We focus on the finite source size effect and the effect of the relative motion of the source to the lens, which are influential to the wave effect in the attolensing. Astrophysical condition that the lensed interference signature can be a probe of the modified gravity theory is demonstrated. The interference signature in the microlensing system is also discussed.Comment: Accepted for publication in IJMP

Fermions on one or fewer Kinks

We find the full spectrum of fermion bound states on a Z_2 kink. In addition to the zero mode, there are int[2 m_f/m_s] bound states, where m_f is the fermion and m_s the scalar mass. We also study fermion modes on the background of a well-separated kink-antikink pair. Using a variational argument, we prove that there is at least one bound state in this background, and that the energy of this bound state goes to zero with increasing kink-antikink separation, 2L, and faster than e^{-a2L} where a = min(m_s, 2 m_f). By numerical evaluation, we find some of the low lying bound states explicitly.Comment: 7 pages, 4 figure

Aharonov-Bohm Radiation of Fermions

We analyze Aharonov-Bohm radiation of charged fermions from oscillating solenoids and cosmic strings. We find that the angular pattern of the radiation has features that differ significantly from that for bosons. For example, fermionic radiation in the lowest harmonic is approximately isotropically distributed around an oscillating solenoid, whereas for bosons the radiation is dipolar. We also investigate the spin polarization of the emitted fermion-antifermion pair. Fermionic radiation from kinks and cusps on cosmic strings is shown to depend linearly on the ultraviolet cut-off, suggesting strong emission at an energy scale comparable to the string energy scale.Comment: 14 pages, 6 figures. Version 2: Expanded discussion on boundary conditions obeyed by Dirac equation mode functions (in Section V B). Acknowledgements and references added. Version 3: Minor changes made in response to referee's comment

Penelusuran Jenis Pekerjaan Para Alumni Jurusan Bahasa Prancis Fakultas Bahasa Dan Seni Universitas Negeri Jakarta

Lulusan jurusan bahasa Prancis UNJ memperoleh pekerjaan di bidang pendidikan dan nonkependidikan misalnya pariwisata, perhotelan, sekretaris, alih bahasa dan interpreting (penerjemahan lisan). Hal ini terjadi karena terbatasnya lapangan kerja di bidang pengajaran apalagi akibat Perubahan orientasi kurikulum di sekolah menengah untuk pelajaran bahasa asing kecuali Inggris, sebagian alumni terpaksa tidak bekerja di lapangan pengajaran bahasa. Penelitian ini menggunakan metode deskriptif . Instrumen dalam penelitian ini adalah angket yang terbagi dalam dua bagian. Bagian pertama (A) merupakan identitas responden dan bagian Kedua (B) merupakan aspek keadaan lulusan dan kurikulum Jurusan Bahasa Prancis. Tujuan penelitian ini untuk memperoleh data terkini mengenai lapangan kerja para alumni Jurusan Bahasa Prancis dan kaitannya dengan kurikulum Jurusan Bahasa Prancis. Hasil penelitian menunjukkan bahwa jenis kompetensi yang dibutuhkan lulusan JBP saat ini di pasar kerja saat ini sangat bervariasi, yang berkaitan dengan kompetensi kebahasaan, kompetensi administrasi dan perkantoran, serta keahlian magerial, dan yang terakhir adalah kompetensi di bidang wiraswasta, yaitu USAha menciptakan lapangan kerja secara mandiri

Uji Bioaktivitas Ekstrak Padina Australis Dari Pesisir Pantai Molas Sulawesi Utara Terhadap Bakteri Staphylococcus Epidermidis

Penelitian ini bertujuan untuk mengetahui bioaktivitas ekstrak P. australis terhadap bakteri S. epidermidis. Metode yang digunakan dalam uji bioaktivitas adalah uji Minimum Inhibitory Concentration (MIC) dan uji Minimum Bactericidal Concentration (MBC). Pengujian bioaktivitas dilakukan dengan menggunakan Rancangan Acak Lengkap (RAL) dengan 5 perlakuan yaitu seri konsentrasi ekstrak 30%, 60%, 90%, kontrol negatif (CMC 1%) dan kontrol positif (cotrimoksazole). Penentuan nilai MIC dengan analisis kekeruhan menggunakan spektrofotometer (ƛ630 nm) sedangkan nilai MBC dengan metode pour plate. Data hasil uji MBC dianalisis menggunakan ANOVA one way kemudian dilanjutkan dengan Uji Tukey. Hasil penelitian ini menunjukkan nilai MIC (Kadar Hambat Minimal) adalah konsentrasi 90%. Hasil analisa statistika ANOVA one way data uji MBC menunjukkan terdapat perbedaan yang signifikan antara pemberian ekstrak dengan total koloni yang tumbuh pada media NA. Uji Tukey menunjukkan bahwa ekstrak P. australis yang menunjukkan bioaktivitas terbaik terhadap S. epidermidis adalah konsentrasi 90% dengan selisih 631 koloni dengan konsentrasi 60% dan 658 koloni dengan konsentrasi 30%. Total koloni yang tumbuh pada media NA dengan perlakuan konsentrasi ekstrak 90% adalah 31 koloni. Ekstrak etanol Padina australis memiliki bioaktivitas dalam menghambat pertumbuhan bakteri S. epidermidis. Nilai MIC ekstrak P. australis terhadap bakteri S. epidermidis adalah konsentrasi 90%. Nilai MBC tidak diketahui dikarenakan pada pengujian lanjut (MBC) konsentrasi yang menunjukkan nilai MIC merupakan konsentrasi tertinggi yaitu 90% masih ditemukan koloni bakteri yang tumbuh pada media N

Saponin Biji Klabet pada Organ Reproduksi Tikus Jantan Sprague Dawley®

Fenugreek seed saponin is one alternative of antifertilitas medicinal plants. Research purposes is to determine the effect of the fenugreek seeds saponin againts the reproductive organ, that is weight and histological structure of the testis and epididymis Sprague Dawley® rat. Research design using randomized design complete. The control group was given distilled water, the treatment group were given fenugreek seed saponin with doses of 40, 80, & 120 mg/kg bw. Treatment is administered orally 1x/day for 24 days. Award saponin start dose of 40 mg/kg bw can reduce the weight of the testes and reduce the size of the diameter of seminiferous tubules. Thick germ cells begin to be affected at higher doses, 120 mg/kg bw. Epididymis weight is reduced significantly compared to the control start at dose 80 mg/kg bw and giving a higher dose, 120 mg/kg bw significantly further reduces the weight of the epididymis. Saponin administration starting dose of 80 mg/kg bw already significantly reduced the thickness of the epithelium of the epididymis. Giving a higher dose of 120 mg/kg bw increasingly signifcant cause epididymal epithelium thickness thinner. It can be concluded that the administration of saponin fenugreek seeds caused a reduction in weight and histological changes in the testis and epididymis structure of rat Spraque Dawley