Energy measurement of 50 MeV proton beam with a NaI(Tl) scintillator

Energy measurement of 50 MeV proton beam produced on the AVF MC-50 Cyclotron was conducted using a detector telescope with a NaI(Tl) scintillator as an E counter. Protons of various energies, elastically and inelastically scattered from the ¹²C target nucleus were measured at four different angles of 35°, 40°, 50° and 55°. We applied the chi-square method to determine the beam energy, which showed a well defined minimum chi-square corresponding to a beam energy of 49.6 ± 2.3 MeV at the 68% confidence level. Also the light output response of NaI(Tl) to proton energies between 31 and 44 MeV is linear within 0.5 MeV and is in good accord with the recent result of Romero et al. [Nucl. Instr. and Meth. A 301 (1991) 241].     

Control of induction motors for both high dynamic performance andhigh power efficiency

The authors attempt to control induction motors with maximum power efficiency as well as high dynamic performance by means of decoupling of motor speed (or motor torque) and rotor flux. For maximum power efficiency, the squared rotor flux is adjusted according to a minimum power search algorithm until the measured power input reaches the minimum. Since the motor speed is dynamically decoupled from the rotor flux, this can be done successfully without any degradation of motor speed responses. The controller depends on rotor resistance but not on stator resistance. However, the performance of the control scheme is robust with respect to variations in rotor resistance because an identification algorithm for rotor resistance is employed. The identification algorithm for rotor resistance has some advantages over the previous methods. To demonstrate the practical significance of the results, some experimental results are presented     

Anisotropy in ac losses near the irreversibility field of Bi2Sr2CaCu2O8

The ac susceptibility under a biased dc field near the irreversibility field (H _irr) of a Bi₂Sr₂CaCu₂O₈ single crystal has been measured. The frequency dependence, the ac-power dependence, and the nearly lossless character of the?″ vs.H _dc curve forH∥a-axis have been roughly explained from a reversible (elastic) fluxoid motion, while those forH∥ c-axis have been explained from a thermally assisted flux-flow (TAFF) model. The obtained parameters are discussed in relation to anisotropic flux-pinning mechanisms in the layered structure of this compound.     

Chamber/Capsule‐Integrated Self‐Healing Coating on Glass for Preventing Crack Propagation

A transparent self‐healing coating incorporating chambers and capsules capable of preventing the propagation of cracks in glass is presented. The main features simultaneously satisfy the requirements of high transmittance (≈90% in the visible region) and the ability to heal random and large‐area cracks in coated‐glass materials (up to 6 cm long, 20 µm wide, and 1 mm deep per chamber). Additionally, the polymerized hydrogel used as the healing agent can stop crack propagation because of its high mechanical strength and good adhesion to glass. Remarkably, the healed glass can withstand a force approximately four times greater than what can be withstood by the unhealed glass after cracking.     

A Small Organic Molecule Blocks EGFR Transport into the Nucleus by the Nonclassical Pathway Resulting in Repression of Cancer Invasion

In addition to the traditional epidermal growth factor receptor (EGFR) signaling pathways, nuclear EGFR has been shown to control multiple cellular functions, including cell proliferation and invasion. It has been reported that EGFR is transported into the nucleus after forming a complex with KPNA/KPNB1 or KPNB1. Herein, it is shown that EGFR can interact with both KP and KPNA, but EGF‐activated EGFR mostly binds with KPNB1 through the pull‐down assay. Also, a small organic molecule ( 1 ), an effective binder of KPNB1, inhibits the interaction between EGFR and KPNB1 in the nonclassical transport pathway, but not KPNA. Furthermore, treatment of cancer cells with 1 noticeably blocks the nuclear entry of EGFR, which results in significant suppression of invasion by lung cancer H1299 cells. These findings show that 1 is an effective inhibitor of EGFR/KPNB1 interactions in vitro, it may be used in cellular studies as a tool to determine the role of nuclear EGFR, and it is a drug candidate.     

Polydopamine‐Graphene Oxide Flame Retardant Nanocoatings Applied via an Aqueous Liquid Crystalline Scaffold

A highly effective flame retardant (FR) nanocoating was developed by conducting oxidative polymerization of dopamine monomer within an aqueous liquid crystalline (LC) graphene oxide (GO) scaffold coating. Due to its high water content, the LC scaffold coating approach facilitated fast transport and polymerization of dopamine precursors into polydopamine (PDA) within the water swollen interlayer galleries. Uniform and periodically stacked (14.5 Å d‐spacing) PDA/GO nanocoatings could be universally applied on different surfaces, including macroporous flexible polyurethane (PU) foam and flat substrates such as silicon wafers. Remarkably, PDA/GO coated PU foam exhibited highly efficient flame retardant performance reflected by a 65% reduction in peak heat release rate at 5 wt% PDA/GO loading in an 80 nm thick coating. While many physically mixed flame retardants are usually detrimental to the mechanical properties of the foam, the PDA/GO coating did not affect mechanical properties substantially. In addition, the PDA/GO coatings were stable in water due to the intrinsic adhesion capability of PDA and the transformation of GO to the more hydrophobic reduced GO form. Given that PDA is produced from dopamine, a molecule prevalent in nature, these findings suggest that significant opportunities exist for new polymeric FRs derived from other natural catechols.     

DiFuse: distributed frequency domain user selection for multi-user MIMO networks

Optimal user selection is important in increasing the capacity of Multi-User Multi-Input Multi-Output Wi-Fi networks, yet it faces a significant challenge; the multi-user diversity gain can be overwhelmed by the formidable Channel State Information (CSI) acquisition overhead. To lessen the overhead, existing schemes adopt the greedy user selection which generally takes the projected norm as the user selection metric, since it considers both the channel power gain and the orthogonality. However, the projected norm suffers from occasional poor user selection, since it does not take the optimal sum capacity gain into account. This paper proposes a new distributed user selection protocol called DiFuse. To employ the sum capacity gain as the user selection metric in DiFuse, each user cleverly computes its own estimated capacity gain by overhearing the CSI feedback from others. The users then simultaneously transmit their feedbacks at the frequency domain via the distributed feedback contention, which effectively reduces the feedback overhead. Then the AP collectively utilizes them for user selection that achieves the maximum positive increment to the sum capacity gain. We implemented the prototype of DiFuse on the USRP N210, and evaluated its performance via both testbed experiments and trace-driven emulations. The results showed that DiFuse outperforms the throughput of the existing scheme called OPUS by 1.8\({\times }\) on average, while maintaining better fairness.     

Facile synthesis of ZnBi<Subscript>2</Subscript>O<Subscript>4</Subscript>-graphite composites as highly active visible-light photocatalyst for the mineralization of rhodamine B

Novel highly active visible-light photocatalysts in the form of zinc bismuth oxide (ZnBi₂O₄) and graphite hybrid composites were prepared by coupling via a co-precipitation method followed by calcination at 450 °C. The as-prepared ZnBi₂O₄-graphite hybrid composites were tested for the degradation of rhodamine B (RhB) solutions under visible-light irradiation. The existence of strong electronic coupling between the two components within the ZnBi₂O₄-graphite heterostructure suppressed the photogenerated recombination of electrons and holes to a remarkable extent. The prepared composite exhibited excellent photocatalytic activity, leading to more than 93% of RhB degradation at an initial concentration of 50mg·L^-1 with 1.0 g catalyst per liter in 150min. The excellent visible-light photocatalytic mineralization of ZnBi₂O₄-1.0graphite in comparison with pristine ZnBi₂O₄ could be attributed to synergetic effects, charge transfer between ZnBi₂O₄ and graphite, and the separation efficiency of the photogenerated electrons and holes. The photo-induced h+ and the superoxide anion were the major active species responsible for the photodegradation process. The results demonstrate the feasibility of ZnBi₂O₄-1.0graphite as a potential heterogeneous photocatalyst for environmental remediation.     

Cover Image,Volume 67, Issue 5

The cover image, by Keuk‐Min Jeong et al., is based on the Research Article Effects of crosslinking agents on the physical properties of polyimide/amino‐functionalized graphene oxide hybrid films, DOI: 10.1002/pi.5555 .