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HANARO, the only large-scale multipurpose research reactor in Korea, houses the neutron research facility with a diverse set of scientific instrumentation. After a long hiatus marred by trips and the following lengthy shutdowns, HANARO is now back on track. With the addition of the cold neutron source, new cold-neutron instruments are available with the previously operating thermal-neutron beam lines, making the total available neutron scattering instruments to users 9. While there is a plan to add an in-beam Mossbauer instrument and a Positron-annihilation spectrometer in the future, the focus is on recovering the user base at the moment. Achieving stable operation in the currently not-so-favorable regulatory environment remains a big challenge for the research facility.

Purpose: The purpose of this study was to examine factors associated with depressive symptoms in the elderly with hearing impairment.Methods: We studied 23 hearing-impaired elderly persons aged 60 years or older. The participants underwent audiometric, neuropsychological, and depression assessments. Neuropsychological tests were subsumed in specific cognitive domains (general cognition, semantic memory, processing speed, executive function). The short version of the geriatric depression scale was administered to obtain depressive symptom scores for each subject.Results: First, among audiometric variables, the pure-tone threshold average, sentence-in-noise recognition scores, and hearing handicap scores were significantly correlated with the depressive symptom scores. Second, among neuropsychological variables, the reaction time on the part A of the Korean version of trail making test for the elderly (K-TMT-E), which is reflective of processing speed, was correlated with the depressive symptom scores. Also, the reaction time on the part B of the K-TMT-E, which is reflective of executive function, was correlated with the depressive symptom scores. Lastly, in the stepwise regression analysis, the pure-tone threshold average and the reaction time on the part B of the K-TMT-E were found to be factors significantly associated with depressive symptom scores.Conclusion: Our findings suggest that, for the hearing-impaired elderly, hearing threshold levels and executive function, especially cognitive flexibility are significant factors associated with depression levels.

The International Conference on Neutron Scattering (ICNS) took place July 9 to 13, 2017 in Daejeon, Korea. This was the 11th conference in the series, starting with the first conference held in Hak...

Purpose: We developed and validated a fetal trisomy detection method for use as a noninvasive prenatal test (NIPT) including a Clinical Laboratory Improvement Amendments (CLIA)-certified bioinformatics pipeline on a cloud-based computing system using both Illumina and Life Technology sequencing platforms for 221 Korean clinical samples. We determined the necessary proportions of the fetal fraction in the cell-free DNA (cfDNA) sample for NIPT of trisomies 13, 18, and 21 through a limit of quantification (LOQ) test. Materials and Methods: Next-generation sequencing libraries from 221 clinical samples and three positive controls were generated using Illumina and Life Technology chemistries. Sequencing results were uploaded to a cloud and mapped on the human reference genome (GRCh37/hg19) using bioinformatics tools. Based on Z-scores calculated by normalization of the mapped read counts, final aneuploidy reports were automatically generated for fetal aneuploidy determination. Results: We identified in total 29 aneuploid samples, and additional analytical methods performed to confirm the results showed that one of these was a false-positive. The LOQ test showed that the proportion of fetal fraction in the cfDNA sample would affect the interpretation of the aneuploidy results. Conclusion: Noninvasive chromosome examination (NICE), a CLIA-certified NIPT with a cloud-based bioinformatics platform, showed unambiguous success in fetus aneuploidy detection.

Two dimensional layered organic-inorganic halide perovskites offer a wide variety of novel functionality such as solar cell and optoelectronics and magnetism. Self-assembly of these materials using solution process (ex. spin coating) makes crystalline thin films synthesized at ambient environment. However, flexibility of organic layer also poses a structure stability issue in perovskite thin films against environment factors (ex. moisture). In this study, we investigate the effect of solvents and moisture on structure and property in the (C6H5(CH2)2NH3)2(Cu, Mn)Cl4 (Cu-PEA, Mn-PEA) perovskite thin films spin-coated on Si wafer using three solvents (H2O, MeOH, MeOH + H2O). A combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) show that relative humidity (RH) has a profound effect on perovskite thin films during sample synthesis and storage, depending on the kind of solvent used. The ones prepared using water (Cu-PEA:H2O, Mn-PEA:H2O) show quite different behavior from the other cases. According to time-dependent XRD, reversible crystalline-amorphous transition takes place depending on RH in the former cases, whereas the latter cases relatively remain stable. It also turns out from XAS that Mn-PEA thin films prepared with solvents such as MeOH and MeOH + H2O are disordered to the depth of about 4 nm from surface.

CdCr2O4 is a cubic spinel with geometrically-frustrated antiferromagnetic interactions between Cr3+ ions. We investigated the structural and magnetic phase transitions in powder samples by using magnetization and neutron diffraction measurements. An antiferromagnetic phase transition was observed at T N = 8.1 K, below which the crystallographic unit cell was tetragonal (c < a = b). Its incommensurate antiferromagnetic ordering below T N resembles dimerized spin chains in the ab planes with the propagation vector k = (0, 0.088, 1). We argue that the Dzyaloshinskii-Moriya interaction and the magnetic frustration play important roles in establishing the observed magnetic ordering.

This work presents the synthesis, structure determination and magnetic properties of a new complex, phenethylammonium tetrachloromanganate(II), (C(6)H(5)CH(2)CH(2)NH(3))(2)MnCl(4) (Mn-PEA). Single crystals of Mn-PEA were obtained from methanol solution using the solvent-evaporation method at room temperature. The crystal structure of Mn-PEA was determined by single-crystal X-ray diffraction (orthorhombic, space group Pbca, a = 7.2075(9), b = 7.3012(14), c = 39.413(6) Å and Z = 4). The structure consisted of an extended [MnCl(4)](2-) network and two phenethylammonium cations to form a two-dimensional halide perovskite structure. Temperature-dependent magnetization measurements indicated that Mn-PEA acted as a weak ferromagnet below T(C) = 44.3 K due to spin canting. Below T(C), the magnetic behavior differed significantly from the behavior commonly observed among weak ferromagnets. The susceptibility depended strongly on the crystal orientation, the external magnetic field strength, and the magnetic history. The isothermal magnetization for two orientations revealed a ferromagnetic moment with a spin-canting angle of 0.04° and a spin-flop transitions with H(sf) = 3.5 T. The weak ferromagnetism, which manifested as spontaneous magnetization and magnetic hysteresis near a field strength of zero, was driven by interplay between the easy axis and the antisymmetric Dzyaloshinsky-Moriya (DM) interaction, leading to directional dependent magnetic behavior.

We have studied the dynamics of the H 2 loaded THF (tetrahydrofuran) clathrate hydrate by using an inelastic neutron scattering technique. At 2 K, a well defined single peak indicative of the ortho ( J = 1) to para ( J = 0) hydrogen transition is observed at 13.6 meV. The neutron spectrum undergoes two distinct changes as the temperature increases. First, additional peaks appear from splitting of the rotational transition above 10 K. Upon further heating, a quasi-elastic neutron scattering (QENS) signal due to hydrogen molecular diffusion through the THF hydrate crystalline lattice grows significantly above 65 K. These results indicate that H 2 molecules trapped inside the THF hydrate crystalline structure undergo two distinct transformations in their dynamical behavior.

HANARO stands for the High-flux Advanced Neutron Application Reactor. It is a 30 MW multi-purpose research reactor constructed and operated by the Korea Atomic Energy Research Institute (KAERI). Its peak unperturbed neutron flux is 5×1014 n/s·cm2, which ranks the reactor among the top ten research reactors in the world. This high power of the reactor and the high flux value may surprise many readers. Even more surprising is that the reactor has already been operating for ten years. Naturally some of the readers might question what activities have taken place and why it has been so quiet for the past decade. We are glad to finally have a chance to reveal this facility to the Neutron News readers.

Polycrystalline compounds of AgxCu1-xGaSe2 were grown by the Bridgman method. x was varied from 1.0 to 0.0 at intervals of 0.2. The optical absorption spectra of these six samples were measured using a photoacoustic spectrometer. From these spectra the authors determined the A, B and C transition energies of AgxCu1-xGaSe2 as functions of the silver concentration x. The transition energies EA and EC relative to transition energy EB were used to obtain both the spin-orbit splitting of the valence bands in a cubic field and the crystal-field splitting of the valence bands in the absence of spin-orbit interaction as functions of x. Furthermore, they estimated the fractional p-like character of the uppermost valence bands for various x, under the assumption that the d levels of Ag and Cu contribute to the spin-orbit splitting according to x.

By combining neutron four-circle diffraction and polarized neutron-diffraction techniques we have determined the complex spin structures of a multiferroic ${\text{YMn}}_{2}{\text{O}}_{5}$ that exhibits two ferroelectric phases at low temperatures. The obtained magnetic structure has spiral components in both the low-temperature ferroelectric phases that are magnetically commensurate and incommensurate, respectively. Among proposed microscopic theories for the magnetoelectric coupling, our results are consistent with both the spin-current mechanism and the magnetostriction mechanism. Our results also explain why the electric polarization changes at the low-temperature commensurate-to-incommensurate phase transition.

Liquid crystals offer many unique opportunities to study various phase transitions with continuous symmetry in the presence of quenched random disorder (QRD). The QRD arises from the presence of porous solids in the form of a random gel network. Experimental and theoretical work support the view that for fixed (static) inclusions, quasi-long-range smectic order is destroyed for arbitrarily small volume fractions of the solid. However, the presence of porous solids indicates that finite-size effects could play some role in limiting long-range order. In an earlier work, the nematic - smectic-A transition region of octylcyanobiphenyl (8CB) and silica aerosils was investigated calorimetrically. A detailed x-ray study of this system is presented in the preceding Paper I, which indicates that pseudo-critical scaling behavior is observed. In the present paper, the role of finite-size scaling and two-scale universality aspects of the 8CB+aerosil system are presented and the dependence of the QRD strength on the aerosil density is discussed., 14 pages, 10 figures, 1 table. Companion paper to "Smectic ordering in liquid crystal - aerosil dispersions I. X-ray scattering" by R.L. Leheny, S. Park, R.J. Birgeneau, J.-L. Gallani, C.W. Garland, and G.S. Iannacchione

The current issue of Neutron News deals principally with presentations of neutron activities at the multipurpose High-flux Advanced Neutron Application Reactor (HANARO) operated by the Korea Atomic Energy Research Institute (KAERI). Before you read the discussions on HANARO, let us give you a brief look back at the history of research reactors in Korea. Certainly HANARO did not come about out of the blue. The first research reactor in Korea was a TRIGA MARK-II, a General Atomics, Co. design. It was built at KAERI's Gongreung-dong campus in Seoul and began operation in 1962. The 100 kW reactor is mediocre at best from today's point of view. Still it came with horizontal beam ports that provided neutrons to the first neutron instruments in Korea. Neutron scattering activities became more visible with the start-up of the second research reactor, the TRIGA MARK-III of a 2 MW thermal power, in 1972. It had four horizontal beam ports for neutron beam applications.