Neutrino sector impacts SUSY dark matter

Motivated by the fact that neutrinos are massive, we study the effect of neutrino Yukawa couplings on neutralino dark matter observables within the framework of a supersymmetric seesaw. We find that neutrino couplings significantly affect the neutralino relic density in regions of parameter space where soft SUSY-breaking slepton masses and/or trilinear couplings are large. Depending on the size of the couplings, the neutralino relic density spans over an order of magnitude in the A-funnel, focus point and stop-coannihilation regions of mSUGRA. We also show that dark matter detection rates can be modified by up to several orders of magnitude.     

Salt‐assisted liquid–liquid extraction in microchannel

In this study, for the first time, salt‐assisted liquid–liquid extraction was performed in a microchannel system. The proposed design is based on the increase of contact surface area between target analytes and extracting phase during the sample and extracting phase transfer in microchannel. In this method, first sample solution, extracting solvent, and salt were mixed by stirrer and simultaneously delivered into a microchannel using a syringe pump. In order to optimize the influential parameters on the extraction efficiency of the proposed method, zidovudine and tenofovir disoproxil fumarate were selected as model analytes. The main parameters such as extracting solvent and its volume, salt amount, pH of sample solution, and microchannel shape, length, and its inner diameter were investigated and optimized. Under the optimized conditions, the proposed method was linear in the range of 0.1–30 µg/mL and R² coefficients were equal to 0.9922 and 0.9947 for zidovudine and tenofovir disoproxil fumarate, respectively. Extraction efficiency of the proposed method was compared with conventional salt‐assisted liquid–liquid extraction. The results show that the proposed design has higher extraction efficiency than conventional salt‐assisted liquid–liquid extraction. Finally, the proposed method was successfully applied for the determination of zidovudine and tenofovir disoproxil fumarate in plasma samples.     

Catalytic activity and facile recovery of a cyclometalated N‐heterocyclic carbene palladium(II) complex immobilized by non‐covalent interactions on reduced graphene oxide

The growing concern about the potentially adverse effects of the production of chemical compounds on the sustainable development of the environment has led to a great deal of efforts to search for low‐cost and environmentally friendly catalytic systems. A pyrene‐tagged N‐heterocyclic carbene palladacycle complex ([Pd{(C,N)C₆H₄CH₂NH(Et)}(Imd‐P)Br]) was prepared by reacting imidazolium salt with dimer ([Pd₂{(C,N)C₆H₄CH₂NH(Et)}₂(μ‐OAc)₂]). Then, it was immobilized onto the surface of reduced graphene oxide (rGO) via π–π stacking forces. The hybrid compound ((NHC)Pd‐rGO) was made in a one‐step process. Various techniques were employed to characterize the compound. In addition, computational studies were used to verify the interaction between the Pd complex and rGO. The catalytic activity of the molecular complex and hybrid material was evaluated in both Suzuki–Miyaura cross‐coupling reactions and reduction of p‐nitrophenol to p‐aminophenol. The catalytic activity of the hybrid material was enhanced in comparison with the corresponding homogeneous analogue. Thus, rGO seems to play a significant role in catalytic activity. Hot filtration experiments show the heterogeneous nature of the catalyst resulting from the strong interaction between pyrene and graphene. The hybrid (NHC)Pd‐rGO material could be recycled up to six times with no decrease in catalytic activity.     

Photocatalytic degradation of carcinogenic Congo red dye in aqueous solution,antioxidant activity and bactericidal effect of NiO nanoparticles

Journal of the Iranian Chemical Society - Face-centered cubic structure of nickel oxide (NiO) nanoparticles with 30 nm average size was synthesized by co-precipitation method with some...     

Hollow Zn/Co Zeolitic Imidazolate Framework (ZIF) and Yolk–Shell Metal@Zn/Co ZIF Nanostructures

Metal–organic frameworks (MOFs) feature a great possibility for a broad spectrum of applications. Hollow MOF structures with tunable porosity and multifunctionality at the nanoscale with beneficial properties are desired as hosts for catalytically active species. Herein, we demonstrate the formation of well‐defined hollow Zn/Co‐based zeolitic imidazolate frameworks (ZIFs) by use of epitaxial growth of Zn‐MOF (ZIF‐8) on preformed Co‐MOF (ZIF‐67) nanocrystals that involve in situ self‐sacrifice/excavation of the Co‐MOF. Moreover, any type of metal nanoparticles can be accommodated in Zn/Co‐ZIF shells to generate yolk–shell metal@ZIF structures. Transmission electron microscopy and tomography studies revealed the inclusion of these nanoparticles within hollow Zn/Co‐ZIF with dominance of the Zn‐MOF as shell. Our findings lead to a generalization of such hollow systems that are working effectively to other types of ZIFs.     

Constrained supersymmetric flipped SU(5) GUT phenomenology

We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, M _in , above the GUT scale, M _GUT. We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino χ and the lighter stau [(t)\tilde]₁{\tilde{\tau}_{1}} is sensitive to M _in , as is the relationship between m _χ and the masses of the heavier Higgs bosons A,H. For these reasons, prominent features in generic (m _1/2,m ₀) planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to M _in , as we illustrate for several cases with tan β=10 and 55. However, these features do not necessarily disappear at large M _in , unlike the case in the minimal conventional SU(5) GUT. Our results are relatively insensitive to neutrino masses.     

Numerical simulation of secondary vortex chamber effect on the cooling capacity enhancement of vortex tube

A vortex tube with additional chamber is investigated by computational fluid mechanics techniques to realize the effects of additional chamber in Ranque–Hilsch vortex tube and to understand optimal length for placing the second chamber in order to have maximum cooling effect. Results show that by increasing the distance between two chambers, both minimum cold and maximum hot temperatures increase and maximum cooling effect occurs at Z/L = 0.047 (dimensionless distance).     

Modification of WS2 nanosheets with beta-cyclodextrone and N-isopropylacrylamide polymers for tamoxifen adsorption and investigation of in vitro drug release

In this research, tungsten disulfide (WS₂) nanosheets were modified with beta-cyclodextrone (βCD) N-isopropylacrylamide polymers (NIPAAP) for adsorption of tamoxifen (TAM) drug. The synthesized WS₂/βCD/NIPAAP samples were characterized by field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) analyses. The adsorption experiments of TAM on WS₂/βCD/NIPAAP were performed as a function of pH, reaction contact time, temperature and drug concentration. The adsorption kinetic data were well fitted to the pseudo-second-order model. Also, the equilibrium data were well described by Langmuir isotherm model. The maximum adsorption capacity of WS₂/βCD/NIPAAP for TAM drug was found to be 62.0 mg/g. The results of regeneration tests showed that the synthesized WS₂/βCD/NIPAAP adsorbent can be easily reused after 6 cycles of adsorption–desorption. Furthermore, TAM drug release was investigated in a simulated system with pH 7.4 at different temperatures. The results showed that the release of TAM drug from WS₂/βCD/NIPAAP carrier at 50 °C and 37 °C was greater than TAM release at 25 °C. Also, the experimental data of drug release were studied by Higuchi, Ritger-Peppas, zero-order and first-order models. The release data were well fitted to the zero-order model indicating a case II transport. The results showed a high stability for TAM drug.