Living fungal hyphae-templated porous gold microwires using nanoparticles as building blocks

Abstract  

A simple and environmentally benign green method is reported to decorate growing fungal hyphae with high loading of gold nanoparticles, which were initially produced using aqueous tea extract as a sole reducing/stabilizing agent. Inoculation of fungal spores in aqueous suspension of nanoparticles led to the growth of intensely red-coloured fungal hyphae due to the accumulation of gold nanoparticles. Heat treatment of these hybrid materials led to the formation of porous gold microwires. This report is thus an interesting example of using green and sustainable approach to produce nanostructured materials which have potential applications in catalysis, sensing and electronics.     

A microextraction procedure based on a task‐specific ionic liquid for the separation and preconcentration of lead ions from red lipstick and pine leaves

First, the extraction and preconcentration of ultratrace amounts of lead(II) ions was performed using microliter volumes of a task‐specific ionic liquid. The remarkable properties of ionic liquids were added to the advantages of microextraction procedure. The ionic liquid used was trioctylmethylammonium thiosalicylate, which formed a lead thiolate complex due to the chelating effect of the ortho‐positioned carboxylate relative to thiol functionality. So, trioctylmethylammonium thiosalicylate played the roles of both chelating agent and extraction solvent simultaneously. Hence, there is no need to use a ligand. The main parameters affecting the efficiency of the method were investigated and optimized. Under optimized conditions, this approach showed a linear range of 2.0–24.0 ng/mL with a detection limit of 0.0010 ng/mL. The proposed method was applied to the extraction and preconcentration of lead from red lipstick and pine leaves samples prior to electrothermal atomic absorption spectroscopic determination.     

Mesoporous silicabis(ethylsulfanyl)propane palladium catalysts for hydrogenation and one-pot two-step Suzuki cross-coupling followed by hydrogenation

The solid phase catalytic activity of mesoporous silicabis(ethylsulfanyl)propane palladium catalysts for hydrogenation and novel one-pot two-step Suzuki cross-coupling followed by hydrogenation is described. The efficiency of catalytic hydrogenation was measured for substrate nitrobenzene with 5, 7 and 14 nm average pore diameter materials. The 5 nm pore material performed best and was also very effective in the catalytic hydrogenation of alkene, nitrile and imine substrates. Novel one-pot two-step Suzuki cross-coupling and hydrogenation was demonstrated using bromonitro- and bromodinitrobenzene and phenylboronic acid as substrates with conversion to the corresponding coupled amino compounds. As a consequence of the high affinity of the sulfur ligands for palladium, none was detected in leaching tests and the catalyst is easily separated and recycled.     

Conformal upper bounds for the eigenvalues of the Laplacian and Steklov problem

In this paper, we find upper bounds for the eigenvalues of the Laplacian in the conformal class of a compact Riemannian manifold (M,g). These upper bounds depend only on the dimension and a conformal invariant that we call “min-conformal volume”. Asymptotically, these bounds are consistent with the Weyl law and improve previous results by Korevaar and Yang and Yau. The proof relies on the construction of a suitable family of disjoint domains providing supports for a family of test functions. This method is interesting for itself and powerful. As a further application of the method we obtain an upper bound for the eigenvalues of the Steklov problem in a domain with C¹ boundary in a complete Riemannian manifold in terms of the isoperimetric ratio of the domain and the conformal invariant that we introduce.     

An easily accessible Re-based catalyst for the selective conversion of methanol: evidence for an unprecedented active site structure through combined operando techniques

Heterogeneous Re/SiO(2) catalysts prepared using a one pot sol-gel synthesis were found to display high activity in the direct, selective methanol conversion to methylal, which is correlated to an unprecedented rhenium oxide structure.     

An Improved Hybrid Adjoint Method in External Aerodynamics Using Variational Technique for the Boundary Integral Based Optimal Objective Function Gradient

An improved hybrid adjoint method to the viscous, compressible Reynold-Averaged Navier-Stokes Equation (RANS) is developed for the computation of objective function gradient and demonstrated for external aerodynamic design optimization. In this paper, the main idea is to extend the previous coupling of the discrete and continuous adjoint method by the grid-node coordinates variation technique for the computation of the variation in the gradients of flow variables. This approach in combination with the Jacobian matrices of flow fluxes refrained the objective function from field integrals and coordinate transformation matrix. Thus, it opens up the possibility of employing the hybrid adjoint method to evaluate the subsequent objective function gradient analogous to many shape parameters, comprises of only boundary integrals. This avoids the grid regeneration in the geometry for every surface perturbation in a structured and unstructured grid. Hence, this viable technique reduces the overall CPU cost. Moreover, the new hybrid adjoint method has been successfully applied to the computation of accurate sensitivity derivatives. Finally, for the investigation of the presented numerical method, simulations are carried out on NACA0012 airfoil in a transonic regime and its accuracy and effectiveness related to the new gradient equation have been verified with the Finite Difference Method (FDM). The analysis reveals that the presented methodology for the optimization provides the designer with an indispensable CPU-cost effective tool to reshape the complex geometry airfoil surfaces, useful relative to the state-of-the-art, in a less computing time.     

Selected Reactions of Diethyl (E)‐1‐(bromomethyl)‐2‐cyanovinylphosphonate with Secondary and Tertiary Amines

An easy regio‐ and stereoselective synthesis of new nitrogenous molecules 2a–e was successfully realized via an effective coupling reaction of diethyl (E)‐1‐(bromomethyl)‐2‐cyanovinylphosphonate 1 with various secondary amines in methanol. Hence, the use of less and more bulky secondary amines gives rise, respectively, to the successive (S_N2′) substitution–isomerization and (S_N2) substitution derivatives 2a–c and 2d–e . Moreover, the addition of tertiary amines to 1 in the same reaction conditions, leads exclusively to the rearranged vinyl ether 3 in good yields.     

Immunoassays Based on Surface-Enhanced Fluorescence using Gap-Plasmon-Tunable Ag Bilayer Nanoparticle Films

A novel gap-plasmon-tunable Ag bilayer nanoparticle film for immunoassays is demonstrated. Different from a traditional Ag monolayer nanoparticle film, a desired number of polyelectrolyte (PEL) layers are deposited on the nanoparticles before the self-assembly of a second Ag nanoparticle layer. Interestingly, by controlling the number of the PEL interlayers, the gap plasmon between the two Ag nanoparticle layers can be tuned across the visible spectral range. The ability of the presented Ag bilayer nanoparticle films in fluorescence enhancement has been examined experimentally. A maximal enhancement of around 15.4 fold was achieved when 7 layers of polyelectrolyte were used. When this optimal Ag bilayer nanoparticle film was applied to fluorescence immunoassay, a performance with approximately 3.3-fold enhancement was obtained compared with that performed on a traditional glass substrate. The experimental results suggest that the presented gap-plasmon tunable Ag bilayer nanoparticle films have great potential in fluorescence-based immunoassays. The method of the bilayer-film construction presented here also provides new insights into the rational design of the plasmonic substrates.     

Efficient Synthesis of New 2H‐Chromene Retinoids Hybrid Derivatives by Suzuki Cross‐coupling Reactions

In an attempt to improve anticancer activity, a series of retinoids–chromene hybrids was described. The novel heterocyclic chromene–retinoids hybrid including oxygen as a heteroatom in a six‐membered cyclic ring (2H‐chromene or 2H‐1‐benzopyran) was designed and synthesized by introducing different groups such as an aromatic or styrylphenyl ring in 6‐position of 2H‐chromene. These novel compounds were synthesized by using the efficient cascades one‐pot process involving Wittig–Horner–Emmons reaction and Suzuki–Miyaura cross‐coupling pallado‐catalyzed reactions with 60% to 90% overall yields. These new compounds were tested against glioblastoma multiforme brain cancer, medulloblastoma, neuroblastoma cell lines, and breast cancer MCF‐7 cell lines. Two of them exhibited an appreciable anti‐tumor activity in the low micromolar range, which opens new perspectives for therapeutic application on humans.     

Dissolution of Cellulose and Lignin with Biobased Ionic Liquids

Journal of Solution Chemistry - Choline-based ionic liquids, involving various alkyl chains lengths and carboxylates derived from biobased acids, have been synthetized with high yields through a...