Sensitive Chemical Compass Assisted by Quantum Criticality

The radical-pair-based chemical reaction could be used by birds for the navigation via the geomagnetic direction. An inherent physical mechanism is that the quantum coherent transition from a singlet state to triplet states of the radical pair could response to the weak magnetic field and be sensitive to the direction of such a field and then results in different photopigments in the avian eyes to be sensed. Here, we propose a quantum bionic setup for the ultra-sensitive probe of a weak magnetic field based on the quantum phase transition of the environments of the two electrons in the radical pair. We prove that the yield of the chemical products via the recombination from the singlet state is determined by the Loschmidt echo of the environments with interacting nuclear spins. Thus quantum criticality of environments could enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure

Nanoscale Imaging of Primary Cilia with Scanning Ion Conductance Microscopy

Primary cilia are hair-like sensory organelles whose dimensions and location vary with cell type and culture condition. Herein, we employed scanning ion conductance microscopy (SICM) to visualize the topography of primary cilia from different cell types. By combining SICM with fluorescence imaging, we successfully distinguished between surface cilia that project outward from the cell surface and subsurface cilia that are trapped below it. The nanoscale structure of the ciliary pocket, which cannot be easily identified using a confocal fluorescence microscope, was observed in SICM images. Furthermore, we developed a topographic reconstruction method using current-distance profiles to evaluate the relationship between set point and topographic image and found that a low set point is important for detecting the true topography of a primary cilium using hopping mode SICM

Modeling of the Division Point of Different Propagation Mechanisms in the Near-Region Within Arched Tunnels

An accurate characterization of the near-region propagation of radio waves inside tunnels is of practical importance for the design and planning of advanced communication systems. However, there has been no consensus yet on the propagation mechanism in this region. Some authors claim that the propagation mechanism follows the free space model, others intend to interpret it by the multi-mode waveguide model. This paper clarifies the situation in the near-region of arched tunnels by analytical modeling of the division point between the two propagation mechanisms. The procedure is based on the combination of the propagation theory and the three-dimensional solid geometry. Three groups of measurements are employed to verify the model in different tunnels at different frequencies. Furthermore, simplified models for the division point in five specific application situations are derived to facilitate the use of the model. The results in this paper could help to deepen the insight into the propagation mechanism within tunnel environments

Konsentrasi Klorofil Daun Padi pada Saat Kekurangan Air yang Diinduksi dengan Polietilen Glikol

KONSENTRASI KLOROFIL DAUN PADI PADA SAAT KEKURANGAN AIR YANG DIINDUKSI DENGAN POLIETILEN GLIKOL ABSTRAK Telah dilakukan penelitian mengenai konsentrasi klorofil daun padi (Oryza sativa L.) kultivar Serayu dan IR 64 pada saat kekurangan air yang diinduksi dengan polietilen glikol (PEG). Penelitian ini bertujuan untuk membandingkan konsentrasi klorofil total, klorofil a dan klorofil b pada daun padi pada saat kekurangan air yang diinduksi dengan PEG 8000 dengan mengkultur tanaman padi pada medium dengan potensial air (PA) 0; -0,5 dan -1 MPa. Sampel helaian daun (lamina) untuk tiap perlakuan diambil sebanyak 1 g, dihaluskan dengan mortar dan pestel, lalu diekstraksi dengan alkohol 95% sampai semua klorofil terlarut. Ekstrak disaring dan supernatan ditampung dalam labu ukur 100 ml, lalu ditambahkan alkohol 95% sampai 100 ml. Konsentrasi klorofil diukur dengan spektrofotometer pada panjang gelombang 649 dan 665 nm. Berdasarkan hasil yang diperoleh, tanaman padi kultivar Serayu dan IR 64 mulai mengalami kekeringan pada PEG dengan PA -0,5 MPa dengan ciri-ciri daun yang kering, menggulung dan batang yang berwarna kecoklatan. Perbedaan konsentrasi klorofil total, klorofil a, dan klorofil b pada daun padi kultivar Serayu dan IR 64 diamati pada PEG dengan PA 0; -0,5 dan -0,1 MPa. Kata kunci: konsentrasi klorofil, polietilen glikol (PEG), kekurangan air, padi kultivar Serayu dan IR 64 THE CHLOROPHYLL CONCENTRATION IN RICE LEAVES UNDER POLYETHYLENE-GLYCOL- INDUCED WATER DEFICIT ABSTRACT A research was conducted to evaluate the concentrations of total clorophyll, chlorophyll a and clorophyll b in rice (Oryza sativa L.) leaves under polyethylene-glycol-induced water deficit. The water deficit was induced by culturing the plants in medium containing polyethylene glycol (PEG) 8000 with water potential (PA) 0;-0,5; and -1 MPa for 2 days. Leaf lamina (1 g) was sampled from each treatment at day 0 and 2. Each sample was ground using porcelain mortar and pestle, and extracted with 95% ethanol until all chlorophyll was dissolved. The extract was filtered, the supernatant was collected in 100 ml flask and added with 95% ethanol until 100 ml. The chlorophyll concentration was measured using spechtrophotometer at 649 and 665 nm. The dry and rolled leaves and brown stems were observed in cultivar Serayu and IR 64 that were cultivated in media containing PEG with PA -0,5 and -1,0 MPa. The concentrations of total chlorophyll, chlorophyll a and b in leaves of cultivar Serayu and IR 64 cultivated in media containing PEG with PA 0; -0,5 and -1,0 MPa were different

Quantum oscillations of nitrogen atoms in uranium nitride

The vibrational excitations of crystalline solids corresponding to acoustic or optic one phonon modes appear as sharp features in measurements such as neutron spectroscopy. In contrast, many-phonon excitations generally produce a complicated, weak, and featureless response. Here we present time-of-flight neutron scattering measurements for the binary solid uranium nitride (UN), showing well-defined, equally-spaced, high energy vibrational modes in addition to the usual phonons. The spectrum is that of a single atom, isotropic quantum harmonic oscillator and characterizes independent motions of light nitrogen atoms, each found in an octahedral cage of heavy uranium atoms. This is an unexpected and beautiful experimental realization of one of the fundamental, exactly-solvable problems in quantum mechanics. There are also practical implications, as the oscillator modes must be accounted for in the design of generation IV nuclear reactors that plan to use UN as a fuel.Comment: 25 pages, 10 figures, submitted to Nature Communications, supplementary information adde

Creation of Entanglement between Two Electron Spins Induced by Many Spin Ensemble Excitations

We theoretically explore the possibility of creating spin entanglement by simultaneously coupling two electronic spins to a nuclear ensemble. By microscopically modeling the spin ensemble with a single mode boson field, we use the time-dependent Fr\"{o}hlich transformation (TDFT) method developed most recently [Yong Li, C. Bruder, and C. P. Sun, Phys. Rev. A \textbf{75}, 032302 (2007)] to calculate the effective coupling between the two spins. Our investigation shows that the total system realizes a solid state based architecture for cavity QED. Exchanging such kind effective boson in a virtual process can result in an effective interaction between two spins. It is discovered that a maximum entangled state can be obtained when the velocity of the electrons matches the initial distance between them in a suitable way. Moreover, we also study how the number of collective excitations influences the entanglement. It is shown that the larger the number of excitation is, the less the two spins entangle each other.Comment: 8 pages, 4 figure