Determination and stress studies on YK-1101,a potential histone deacetylase,by HPLC-UV and HPLC-TOF/MS methods

YK- 1101, with its structure as S-（（E）-4-（（7S, 10S,Z）-4-ethylidene-7-isopropyl-2,5,8,12- tetraoxo -9-oxa- 16-thia-3,6,13,18-tetraazabicyclo[ 13.2.1 ]octadeca- 1 （17）, 15（ 18）-dien- 10-yl）but-3-en- 1 -y l） ethanethioate, is synthesized as a potential histone deacetylase inhibitor. Its quality and stability under various stress conditions are not fully understood. In this study, a high performance liquid chromatographic （HPLC） method was established and validated for the analysis of YK-1101 bulk drug samples. The chromatographic separation was performed on a C18 column with acetonitrile and water as mobile phase in a gradient elution. Based on the established method, the stability studies of YK-1101 under various stress conditions were carried out. YK-1101 was shown to undergo degradation under basic and acidic stress conditions, while it was stable under oxidative, photolytic and thermal conditions. In addition~ a time of flight mass spectrometer （TOF/MS） was coupled to HPLC for the characterization of major degradation products produced under basic and acidic stress conditions. Their degradation pathways were also discussed.

Emergent symmetry in quantum phase transition:From deconfined quantum critical point to gapless quantum spin liquid

The emergence of exotic quantum phenomena in frustrated magnets is rapidly driving the development of quantum many-body physics,raising fundamental questions on the nature of quantum phase transitions.Here we unveil the behaviour of emergent symmetry involving two extraordinarily representative phenomena,i.e.,the deconfined quantum critical point(DQCP)and the quantum spin liquid(QSL)state.Via large-scale tensor network simulations,we study a spatially anisotropic spin-1/2 square-lattice frustrated antiferromagnetic(AFM)model,namely the J1x-J1y-J2 model,which contains anisotropic nearestneighbor couplings J1x,J1y and the next nearest neighbor coupling J2.For small J1y/J1x,by tuning J2,a direct continuous transition between the AFM and valence bond solid phase is observed.With growing J1y/J1x,a gapless QSL phase gradually emerges between the AFM and VBS phases.We observe an emergent O(4)symmetry along the AFM–VBS transition line,which is consistent with the prediction of DQCP theory.Most surprisingly,we find that such an emergent O(4)symmetry holds for the whole QSL–VBS transition line as well.These findings reveal the intrinsic relationship between the QSL and DQCP from categorical symmetry point of view,and strongly constrain the quantum field theory description of the QSL phase.The phase diagram and critical exponents presented in this paper are of direct relevance to future experiments on frustrated magnets and cold atom systems.

Gapless quantum spin liquid and global phase diagram of the spin-1/2 J_(1)-J_(2) square antiferromagnetic Heisenberg model

The nature of the zero-temperature phase diagram of the spin-1/2 J_(1)-J_(2)Heisenberg model on a square lattice has been debated in the past three decades,and it remains one of the fundamental problems unsettled in the study of quantum many-body theory.By using the state-of-the-art tensor network method,specifically,the finite projected entangled pair state(PEPS)algorithm,to simulate the global phase diagram of the J_(1)-J_(2)Heisenberg model up to 24×24 sites,we provide very solid evidences to show that the nature of the intermediate nonmagnetic phase is a gapless quantum spin liquid(QSL),whose spin-spin and dimer-dimer correlations both decay with a power law behavior.There also exists a valence-bond solid(VBS)phase in a very narrow region 0.56■J_(2)/J_(1)≤0.61 before the system enters the well known collinear antiferromagnetic phase.We stress that we make the first detailed comparison between the results of PEPS and the well-established density matrix renormalization group(DMRG)method through one-to-one direct benchmark for small system sizes,and thus give rise to a very solid PEPS calculation beyond DMRG.Our numerical evidences explicitly demonstrate the huge power of PEPS for highly frustrated spin systems.Finally,an effective field theory is also proposed to understand the physical nature of the discovered gapless QSL and its relation to deconfined quantum critical point(DQCP).