Top quark decays with flavor violation in the B-LSSM

The decays of top quark $t\rightarrow c\gamma,\;t\rightarrow cg,\;t\rightarrow cZ,\;t\rightarrow ch$ are extremely rare processes in the standard model (SM). The predictions on the corresponding branching ratios in the SM are too small to be detected in the future, hence any measurable signal for the processes at the LHC is a smoking gun for new physics. In the extension of minimal supersymmetric standard model with an additional local $U(1)_{B-L}$ gauge symmetry (B-LSSM), new gauge interaction and new flavor changing interaction affect the theoretical evaluations on corresponding branching ratios of those processes. In this work, we analyze those processes in the B-LSSM, under a minimal flavor violating assumption for the soft breaking terms. Considering the constraints from updated experimental data, the numerical results imply $Br(t\rightarrow c\gamma)\sim5\times10^{-7}$, $Br(t\rightarrow cg)\sim2\times10^{-6}$, $Br(t\rightarrow cZ)\sim4\times10^{-7}$ and $Br(t\rightarrow ch)\sim3\times10^{-9}$ in our chosen parameter space. Simultaneously, new gauge coupling constants $g_{_B},\;g_{_{YB}}$ in the B-LSSM can also affect the numerical results of $Br(t\rightarrow c\gamma,\;cg,\;cZ,\;ch)$.Comment: 20 pages, 4 figures, published in EPJC. arXiv admin note: substantial text overlap with arXiv:1803.0990

catena-Poly[[(diaqua­calcium)-bis­(μ-2-fluorobenzoato)-1′:1κ3 O:O,O′;1:1′′κ3 O,O′:O] 2,2′-bipyridine hemi­solvate]

In the title compound, {[Ca(C7H4FO2)2(H2O)2]·0.5C10H8N2}n, the CaII atom is coordinated by eigth O atoms from four 2-fluoro­benzoate ligands and two water mol­ecules, resulting in a distorted CaO8 square-anti­prismatic coordination environment. The 2-fluoro­benzoate ligand bridges two symmetry-related CaII atoms, giving rise to a chain structure extending along [100]. The distances between the Ca atom and its two symmetry-related counterparts are 4.054 (2) and 4.106 (2) Å. The polymeric chains are connected by classical O—H⋯N hydrogen bonds into a layer structure parallel to (010). The layers are connected by non-classical C—H⋯F hydrogen bonds into a three-dimensional supra­molecular structure. O—H⋯O and C—H⋯O inter­actions also occur. The uncoordinated 2,2′-bipyridine mol­ecule is located on a centre of symmetry at the mid-point of the bond between the two heterocycles. One of the two benzene rings is disordered over two sites with occupancy factors of 0.60 and 0.40

A critical review on bismuth and antimony halide based perovskites and their derivatives for photovoltaic applications: Recent advances and challenges

In the past decade, lead halide perovskites experienced impressive progress in photovoltaics with the certified device conversion efficiency over 25%, owing to their outstanding optoelectronic properties. However, the toxicity and environmental instability of the core lead halide materials would strongly limit their commercialization. Within this scenario, research investigations directed at assessing the properties and opportunities offered by emerging lead-free halide perovskites are becoming everyday more relevant to pinpoint new low-cost/low-toxicity solutions for solar-to-electricity conversion. In this review, group VA metal halide based perovskites, namely those of bismuth (Bi) and antimony (Sb), and their derivatives with different valence states are classified based on the formulae A3B2X9 and A2AgBX6, also known as double perovskites, and AgaBibXa+3b, called rudorffites (A = MA, FA, Cs, Rb, etc.; B = Bi, Sb; X = I, Br, Cl). Here, we summarize the recent progress in the exploitation of these materials, with special attention devoted to the description of the crystal structures, thin film preparation methods and performances in real devices, including both theoretical insights and experimental observations. With this survey, we are able to provide reasonable perspectives for the future development of high-performance photovoltaic devices based on lead-free bismuth/antimony halide based perovskites and their derivatives

Minimization of the environmental impact in the chrome tanning process by a closed-loop recycling technology

Content: It is acknowledged that conventional chrome tanning in leather processing discharges significant amounts of chromium, dissolved solids and chlorides. The recycling technology is one of the effective solutions to reduce the environmental impact of chrome tanning waste water at source. In this work, a novel closed recycling technology of chrome tanning wastewater was applied in the tanning process of the goat skins at a pilot scale level. The properties of chrome tanning liquors obtained by the recycling technology and the resultant crust were analyzed. The results show that this close recycling process works well. The contents of Cr2O3, total organic carbon, ammonia nitrogen and chloride ion in the waste water tend to accumulate with the increase of recycling times, and finally reach a balance after 5 times of recycling. The obtained leather sample is full, soft and having a shrinkage temperature comparable to that of conventional chrome tanned leather. SEM images indicate that the resulting leather samples by this recycling technology show fine and clean grain and well-dispersed fibrils. TG and DSC results show that the thermal stability of wet blue leathers tanned by the circular process are similar to those tanned by conventional chrome tanning process. Compared with conventional chrome tanning technology, water, salt and chrome tanning agent are saved in this process, and the zero emission of chrome tanning wastewater is realized. The cleaner production technology exhibits promising application prospect for its economic and environmental benefits. Take-Away: 1. A novel closed recycling technology of chrome tanning wastewater was applied in the tanning process of the goat skins at a pilot scale level. 2. The chrome tanning liquors obtained by the recycling technology and the resultant crust were analyzed. 3. Water, Sodium chloride and chrome tanning agent are saved by the closed recycling technology, and the zero emission of chrome tanning wastewater is realized

Piperazine-2,3,5,6-tetra­one

The mol­ecule of the title compound, C4H2N2O4, is located around an inversion center and the four O atoms are in the 2,3,5,6-positions of the piperazine ring. In the crystal, bifurcated N—H⋯O hydrogen bonds link the mol­ecules into a corrugated layer parallel to (101)

In vitro specific interactions revealed the infective characteristics of fungal endophytes to grapevine

In the present study a method for co-culture of fungal endophytic strains and grape cells was developed in order to study their interactions, and filter candidates for further safe inoculation in the vineyard. Analysis of morphological and physiological traits was performed by measuring the plant callus and fungal growth, plant cells viability, degree of cell oxidation and the scale of contact or its absence as reaction of the fungal endophyte to the presence of the plant callus. Accordingly, endophytic fungal strains (EFS) were classified on scale of invasion into categories (strong - medium - weak invasive), as well as the contact between the two partners (grow into - grow onto - contact - no contact) and the grape cell oxidation degree (normal (no oxidation) - light - moderate - serious). More included the dominance and distribution of EFS in the plant host, and correlation plots of physiological traits during plant callus and endophytic fungi co–culture were calculated