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[en] The formation of a common mycorrhizal network (CMN) between roots of different plant species enables nutrient transfers from one plant to another and their coexistence. However, almost all studies on nutrient transfers between CMN-connected plants have separately, but not simultaneously, been demonstrated under the same experimentation. Both conspecific and heterospecific seedlings of Cinnamomum camphora, Bidens pilosa, and Broussonetia papyrifera native to a karst habitat in southwest China were concurrently grown in a growth microcosm that had seven hollowed compartments (six around one in the center) being covered by 35.0-μm and/or 0.45-μm nylon mesh. The Ci. camphora in the central compartment was supplied with or without Glomus etunicatum and 15N to track N transfers between CMN-connected conspecific and heterospecific seedlings. The results showed as follows: significant greater nitrogen accumulations, biomass productions, 15N content, % Ntransfer, and the Ntransfer amount between receiver plant species ranked as Br. papyrifera≈Bi. pilosa > Ci. camphora under both M+ and M−, and as under M+ than under M− for Ci. camphora but not for both Bi. Pilosa and Br. papyrifera; the CMN transferred more nitrogen (15N content, % Ntransfer, and Ntransfer amount) from the donor Ci. camphora to the heterospecific Br. papyrifera and Bi. pilosa, with a lower percentage of nitrogen derived from transfer (%NDFT). These findings suggest that the CMN may potentially regulate the nitrogen transfer from a donor plant to individual heterospecific receiver plants, where the ratio of nitrogen derived from transfer depends on the biomass strength of the individual plants.
[en] Hawking radiation, originally derived in the ray optics limit, exhibits the unfortunate trans-Planckian problem—a Hawking photon near spatial infinity, if back-tracked to the immediate vicinity of the horizon is hugely blue-shifted and found to have had trans-Planckian energy. (And if back-tracked all the way to the horizon, the photon is formally infinitely blue-shifted, and formally acquires infinite energy.) Unruh has forcefully argued that this implies that the Hawking flux represents a vacuum instability in the presence of a horizon, and that the Hawking photons are actually emitted from some region exterior to the horizon. We seek to make this idea more precise and somewhat explicit by building a purely kinematical model for Hawking evaporation based on two Vaidya spacetimes (outer and inner) joined across a thin time-like boundary layer. The kinematics of this model is already quite rich, and we shall defer consideration of the dynamics for subsequent work. In particular we shall present an explicit calculation of the 4-acceleration of the shell (including the effects of gravity, motion, and the outgoing null flux) and relate this 4-acceleration to the Unruh temperature.
[en] Conductive tracks represent a critically important class of component for high-performance transient electronics. However, the fabrication of transient conductors normally employs expensive and complex sputtering or evaporation process. Herein, we prepared novel silver nanowire (AgNW) and PEDOT:PSS transient tracks by sintering at 100 °C for only 10 min. It is demonstrated that the AgNW/PEDOT:PSS tracks are highly conductive with resistance of 8.5 μOhm·m and highly flexible. Impressively, the AgNW/PEDOT:PSS tracks fall off the glass substrates in only 170 s after being immersed in water due to the swelling of PEDOT:PSS. The rapid failure of the AgNW/PEDOT:PSS tracks makes it a potential candidate for conductors in transient electronics. (paper)
[en] This work aims at predicting the micro-hardness of XC38 steel using the experiments plans as well as study of tribological behavior of this steel. The heat treatments were considered by adopting the factorial plans 22 methodology at two factors (temperature ‘T’ and holding time ‘t’), each at two levels (−1, +1). The results obtained allowed lead to a mathematical model predicting the micro-hardness ‘Hv’ in every point of the study field. Moreover, the curves of the responses surfaces clearly show the influence of two factors studied (T, t) on ‘Hv’. Mechanical characterization of treated samples showed a significant increase in the micro-hardness, which achieve to 76% for the treated sample at 850 °C during 2 h compared to untreated state. An investigation of wear tracks morphology shows that friction under a load of 10 N results in predominant adhesive wear, while a load of 2 N favor abrasive wear. (paper)
[en] This paper presents the methodology and results of the national radon survey in Bulgaria and its spatial variability. The measurements were carried out in 2778 dwellings using CR-39 track detectors over two successive 9 and 3-month periods from April 2015 to March 2016. The arithmetic (AM) and geometric (GM) means of annual indoor radon concentration were 111 ± 105 Bq/m3 and 81 Bq/m3 (GSD = 2.15), respectively. The distribution of data has been accepted to be log-normal. Two hypotheses have been investigated in the paper. The first one was a spatial variation of indoor radon concentration and the second was spatiality of the factor that influences radon variation. The indoor radon concentrations in the 28 districts have been significantly different, which prove the first hypothesis. The influence of the factors, geology (geotectonic unit, type of rock, and faults distance of the measuring site), type of the region, and the presence of the basement in the building on radon spatial variation, was examined. The analyses have been shown that they significantly affect radon variations but with a relatively small contribution in comparison to the radon variation between district. Furthermore, the significance and contribution of the investigated factors were different in each district, which confirmed the second hypothesis for their spatiality.
[en] The structural information of coronary arteries has important clinical value for quantitative diagnosis and treatment of coronary artery disease. In this study, a deep feature regression (DFR) method based on a convolutional regression network (CRN) and a stable point clustering mechanism for 3D vessel segmentation is proposed. First, the vessel model is constructed by a vessel section generator and a series of deviation parameter estimators. The generator provides 2D images for the training and prediction processes, while the estimators calculate pose parameters of an input vessel section. Second, estimators are trained by a series of CRNs, in which deep vessel features are automatically learned from 600 000 sample images. Third, we propose a stable point clustering mechanism that evaluates the reliability of the CRN estimation through iterative regression of vessel parameters. This mechanism eliminates the outliers, thereby increasing tracking robustness. Finally, we present a vessel segmentation algorithm using trained deviation parameter estimators. And, the termination criteria are designed based on both the number of stable points and an intensity constraint. The proposed method is evaluated on a public coronary artery data set. The average overlapping ratio and error are 97.5% and 0.27 mm, respectively. A quantitative test on a public cerebral artery data set demonstrates that the proposed DFR method tracks the vessel centerline with high accuracy, for which the average error is less than 0.33 mm. (paper)
[en] Energetic heavy ions during their passage through a material medium lose their energy via the processes of ionization and excitation of the target atoms resulting in the process of crosslinking and chain-scissoring, finally leading to the formation of latent tracks in polymers. The track recording property of polymers has led to their utility in many scientific and technological applications. In the present talk we have focused on certain important studies carried out in our group based on the recorded ion tracks in polymers. In the first study, we observed that the track recording properties of polymers provides an excellent way to measure average energy loss, range and straggling. In the second study, we noticed that the ion tracks recorded in the polymers provide the excellent way for the fabrication of membranes with controlled pore size and also as templates for the fabrication of nano/micro structure. In the third study, we have synthesized PVA-Ag nano-composites by in-situ chemical reduction method and preparation of their films by solution casting method. On irradiation, due to the formation of ion tracks the properties of such nano-composites can be tuned to the desired extent. All these studies and many other studies involving ion tracks have opened many new channels for the research activities in diverse fields
[en] Cloud chamber contributes to radiation education by facilitating observation of particle tracks formed by radiation. Peltier-based chamber achieves cooling without the need for dry ice,. we developed a cloud chamber based on peltier thermoelectric modules and has a multilayered heat insulation system to maintain a stable cool environment. It produces sharp particle tracks without requiring a dark room for observing the tracks. Its large top window (diameter of 12.5 cm) provides a relatively wider observation field capable of accommodating five to six students at a time. (authors)
[en] Unconventional superconductivity typically is closely related to the suppression of ordered states which possibly compete or coexist with superconductivity in the underdoped region. The overdoped systems are usually assumed to stay in a rather conventional Fermi liquid state. However, for iron-based superconductors, experiments indicate that the heavily hole-doped end-member KFeAs, together with its sister compounds, are more complicated including the possibility of emerging electronic nematic order. We present elasto-resistivity measurements of KFeAs, revealing a divergent nematic susceptibility. The evolution of nematic susceptibility is also tracked with isovalent doping and electron doping on the K site. Our results point to unexpected nematic critical point(s) in those overdoped superconductors.