Nematic and chiral orders for planar spins on triangular lattice

We propose a variant of the antiferromagnetic XY model on the triangular lattice to study the interplay between the chiral and nematic orders in addition to the magnetic order. The model has a significant bi-quadratic interaction of the planar spins. When the bi-quadratic exchange energy dominates, a large temperature window is shown to exist over which the nematic and the chiral orders co-exist without the magnetic order, thus defining a chiral-nematic state. The phase diagram of the model and some of its critical properties are derived by means of the Monte Carlo simulation.Comment: minor change

Analysis of historical meteor and meteor shower records: Korea, China, and Japan

We have compiled and analyzed historical Korean meteor and meteor shower records in three Korean official history books, Samguksagi which covers the three Kingdoms period (57 B.C -- A.D. 935), Goryeosa of Goryeo dynasty (A.D. 918 -- 1392), and Joseonwangjosillok of Joseon dynasty (A.D. 1392 -- 1910). We have found 3861 meteor and 31 meteor shower records. We have confirmed the peaks of Perseids and an excess due to the mixture of Orionids, north-Taurids, or Leonids through the Monte-Carlo test. The peaks persist from the period of Goryeo dynasty to that of Joseon dynasty, for almost one thousand years. Korean records show a decrease of Perseids activity and an increase of Orionids/north-Taurids/Leonids activity. We have also analyzed seasonal variation of sporadic meteors from Korean records. We confirm the seasonal variation of sporadic meteors from the records of Joseon dynasty with the maximum number of events being roughly 1.7 times the minimum. The Korean records are compared with Chinese and Japanese records for the same periods. Major features in Chinese meteor shower records are quite consistent with those of Korean records, particularly for the last millennium. Japanese records also show Perseids feature and Orionids/north-Taurids/Leonids feature, although they are less prominent compared to those of Korean or Chinese records.Comment: 29 pages, 7 figures. To appear in Icaru

Ion-exchange membranes for blue energy generation: A short overview focused on nanocomposite

Blue energy can be harvested from salinity gradients between saline water and freshwater by reverse electrodialysis (RED). RED as a conversion technique to generate blue energy has received increasing attention in recent decades. As part of the RED system, ion exchange membranes (IEMs) are key elements to the success of future blue energy generation. However, its suboptimal performance often limits the applications and stagnates the deve­lopment of the technology. The key properties of IEMs include ion exchange capacity, perm­selectivity, and electrical resistance. The enhancement of such physical and electrochemical properties is crucial for studying energy production with acceptable output efficiency on a commercial scale. Recently, many studies have tried blending nanotechnology into the membrane fabrication process. Hybridizing inorganic nanomaterials with an organic polymeric material showed the great potential of improving electrical conductivity and perm­selectivity, as well as other membrane characteristics for power performance. In this short review, recent developments on the IEM synthesis in association with potential nanomaterials are reviewed and raising issues regarding the application and commercialization of RED-based energy production are discussed