Phase transitions in a holographic s $$$$ p model with back-reaction

In a previous paper (Nie et al. in JHEP 1311:087, arXiv:1309.2204 [hep-th], 2013), we presented a holographic s \(+\) p superconductor model with a scalar triplet charged under an SU(2) gauge field in the bulk. We also study the competition and coexistence of the s-wave and p-wave orders in the probe limit. In this work we continue to study the model by considering the full back-reaction. The model shows a rich phase structure and various condensate behaviors such as the “n-type” and “u-type” ones, which are also known as reentrant phase transitions in condensed matter physics. The phase transitions to the p-wave phase or s \(+\) p coexisting phase become first order in strong back-reaction cases. In these first order phase transitions, the free energy curve always forms a swallow tail shape, in which the unstable s \(+\) p solution can also play an important role. The phase diagrams of this model are given in terms of the dimension of the scalar order and the temperature in the cases of eight different values of the back-reaction parameter, which show that the region for the s \(+\) p coexisting phase is enlarged with a small or medium back-reaction parameter but is reduced in the strong back-reaction cases.     

Effects of carbon contents on morphology and electrical properties of Li2MnSiO4/C prepared by a vacuum solid-state method

To improve the electrochemical performance of Li₂MnSiO₄ with low electric conductivity, the Li₂MnSiO₄/C composite are synthesized by a vacuum solid-state reaction of a mixture of SiO₂, LiCH₃COO, Mn(CH₃COO)₂ and designed mass of C₆H₁₂O₆ · H₂O as carbon sources. The crystalline structure and morphology of products are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser scattering technology (LS) respectively. The tested results show that carbon doping decrease the crystallite sizes of products, but keep the aggregation of the particles and made the impurity increased instead. The results of constant current charge-discharge prove that the mixed carbon improve Li⁺ transmission performance and decrease inner polatization resistance of Li₂MnSiO₄ materials, but can not prevent the collapse of Li₂MnSiO₄ crystal structure. While the galvanostatic intermittent titration technique (GITT) results demonstrate that the primary reason for the improved electrochemical performance can be attributed to increased Li-ion diffusion coefficient $(D_{Li^ + } )$ as a result from carbon doping.     

The Photo‐Nazarov Reaction: Scope and Application

The reaction conditions and scope of the photo‐Nazarov reaction of aryl vinyl ketones were investigated. In contrast to the conventional acid‐catalyzed methods, this photolytic electrocyclization proceeds in the neutral or basic conditions. Irradiating substrates bearing various aromatic rings, acid‐sensitive groups, cyclohexenyl, cycloheptenyl, and unsaturated pyran with UV‐light (254 nm) smoothly yielded hexahydrofluorenones and related structures. This photo‐Nazarov reaction could also be applicable to the substrates carrying β‐alkyl groups on the enone, which gave corresponding polycyclic rings containing quaternary centers. These photo‐electrocyclized products may prove useful for synthesizing a variety of natural products and their derivatives. Further application of this mild photo‐Nazarov reaction in the synthesis of taiwaniaquinol B was achieved.     

A Protic Ionic Liquid Catalyzes CO2 Conversion at Atmospheric Pressure and Room Temperature: Synthesis of Quinazoline‐2,4(1H,3H)‐diones

The chemical fixation of CO₂ under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO₂‐reactive protic ionic liquid (PIL), [HDBU⁺][TFE^?], was designed by neutralization of the superbase 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO₂ and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO₂ with 2‐aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline‐2,4(1H,3H)‐diones in excellent yields.     

Design and Synthesis of Polyoxazole‐based Macrocycles Tethered with a Phosphonate Group

We present the design and synthesis of polyoxazole‐based macrocycles containing a phosphonate group. A reliable route was established that allows for convenient and versatile incorporation of various phosphonate functionalities such as phosphonate ester, acid, and salt at the macrocyclic ring periphery. Such unprecedented macrocyclic compounds are anticipated to be appealing candidates as telomerase inhibitors.     

An efficient ionic liquid supported divergent assembly of 3,6-branched glucosamine-containing pentasaccharide

We utilized the glycosyl acceptor tagging method with ionic liquid support for synthesis of the core segment of Clostridium botulinum C2 toxin ligand through a divergent synthetic strategy without chromatographic purification.The total yield was 57.1% and the reaction was completed in 10 h.The efficient ionic liquid supported glycosylation and purification procedure was applied for the synthesis of branched glucosamine-containing oligosaccharides for the first time,which expanded the scope of ionic liquid supported synthesis of biologically important oligosaccharides.     

Synthesis of biodiesel over ZnO/Ca(OH)2/KF catalyst prepared by the grinding method

A novel ZnO/Ca(OH)₂/KF solid base catalyst was prepared by the grinding method and applied to biodiesel synthesis by the transesterification of soybean oil. The effect of various parameters such as KF molar amount, calcination temperature, the amount of catalyst, molar ratio of methanol to oil, reaction temperature, and time on the activity of the catalyst were investigated. The catalysts were characterized by several techniques of thermogravimetry/derivative thermogravimetry, X–ray diffraction, Hammett indicator method, and scanning electron microscopy. The analysis results indicated that the KF interacted with Ca(OH)₂ and formed KCaF₃ phase before calcination of the catalyst. The formed KCaF₃ crystal phase was the main catalytic active component for the catalyst activity. In addition, the basicity of ZnO/Ca(OH)₂/KF was greatly influenced by the different calcination temperates, and the catalyst activity was correlated closely with the basicity. A desired biodiesel yield of 97.6 % was obtained at catalyst amount of 3 %, methanol/oil of 12:1, and reaction time of 1.5 h at 65 °C.