Single-Molecule Two-Color Coincidence Detection of Unlabeled alpha-Synuclein Aggregates

Protein misfolding and aggregation into oligomeric and fibrillar structures is a common feature of many neurogenerative disorders. Single-molecule techniques have enabled characterization of these lowly abundant, highly heterogeneous protein aggregates, previously inaccessible using ensemble averaging techniques. However, they usually rely on the use of recombinantly-expressed labeled protein, or on the addition of amyloid stains that are not protein-specific. To circumvent these challenges, we have made use of a high affinity antibody labeled with orthogonal fluorophores combined with fast-flow microfluidics and single-molecule confocal microscopy to specifically detect α-synuclein, the protein associated with Parkinson's disease. We used this approach to determine the number and size of α-synuclein aggregates down to picomolar concentrations in biologically relevant samples.     

Effector Regulated Catalytic Cyclization of Alkynoic Acids Using Pt2L4 Cages

Metabolic pathways are highly regulated by effector molecules that influences the rate of enzymatic reactions. Inspired by the catalytic regulation found in living cells, we report a Pt₂L₄ cage of which the activity can be controlled by effectors that bind inside the cage. The cage shows catalytic activity in the lactonization of alkynoic acids, with the reaction rates dependent on the effector guest bound in the cage. Some effector guests enhance the rate of the lactonization by up to 19-fold, whereas one decreases it by 5-fold. When mixtures of specific substrates are used, both starting materials and products act as guests for the Pt₂L₄ cage, enhancing its catalytic activity for one substrate while reducing its activity for the other. The reported regulatory behavior obtained by the addition of effector molecules paves the way to the development of more complex, metabolic-like catalyst systems.     

Dual Chromophoric Meso-Aryl BODIPYs with Aggregation Induced Red-Emission Characteristics: Optical Properties and their Application in Fe3+ Detection

Herein, we report the design of meso-aryl BODIPYs as a structural motif for aggregation-caused quenching (ACQ) to aggregation-induced emission (AIE) transformation. A series of meso-aryl BODIPY derivatives were synthesized, by systematically increasing the size of the chromophore at the meso-position from phenyl to pyrene. The effect of various factors, such as the aryl ring size, solvents, viscosity, and metal cations, on the photophysical properties was analyzed. The emission properties are well correlated with the flexibility of the aromatic ring for free rotation around the C_aryl−C_BODIPY bond. Accordingly, meso-phenanthrene BODIPY ( PhB ) has the highest emission characteristics. The emission property of less bulky aryl-substituted BODIPYs increases by increasing the solvent viscosity. The interaction of Fe³⁺ ions with aryl-BODIPYs provides a prominent photophysical response based on Lewis-acid supported decomplexation of BF₂ in aryl-BODIPYs. The bichromophoric meso-aryl BODIPYs exhibit notable intramolecular excitation energy transfer from the aromatic ring to the BODIPY core, which is higher in meso-anthracene BODIPY( AB ). Hence, decorating BODIPYs with polycyclic aromatic systems generates a twisted structure, which inhibits the π-π stacking between the planar aromatic molecules. This can be proposed as an effective approach at the molecular level to convert planar aryl luminophores having ACQ to AIEgens. Besides, the meso-pyrene BODIPY derivative shows excellent mechanofluorochromic behaviour.     

Percolation of even sites for random sequential adsorption

Consider random sequential adsorption on a red/blue chequerboard lattice with arrivals at rate 1 on the red squares and rate λ$\lambda$ on the blue squares. We prove that the critical value of λ$\lambda$, above which we get an infinite blue component, is finite and strictly greater than 1.     

Identities for the Ramanujan zeta function

We prove formulas for special values of the Ramanujan tau zeta function. Our formulas show that L(Δ,k)$L(\mathrm{\Delta },k)$ is a period in the sense of Kontsevich and Zagier when k?12$k?12$. As an illustration, we reduce L(Δ,k)$L(\mathrm{\Delta },k)$ to explicit integrals of hypergeometric and algebraic functions when k∈{12,13,14,15}$k\in \{12,13,14,15\}$.     

Heat and mass transfer on unsteady three-dimensional convective MHD flow past a porous plate moving in a parallel free stream

The unsteady three-dimensional convective flow of a viscous incompressible, electrically conducting fluid over a vertical, insulated, porous surface moving in a parallel free stream has been investigated, which flows belong to a separate class of problem of boundary layer theory. The effects of heat and mass transfer on this unsteady laminar flow past porous surface with transverse sinusoidal suction and oscillatory wall temperature have been analysed and discussed.     

Studies of nonlinear optical properties of PicoGreen dye using Z-scan technique

In this paper we study the nonlinear optical properties of PicoGreen dye. The investigations involve the single-beam Z-scan technique and measurements were carried out at different incident intensities. Both open and closed aperture Z-scan techniques were performed at 532 nm and it was found that the dye exhibited a reverse saturable absorption with significant nonlinear absorption coefficient and intensity-dependent negative nonlinear refraction coefficient, indicating self-defocusing phenomena. The third-order nonlinear susceptibility and optical limiting threshold were also measured.     

Multiple-magnetic field 139La NMR and density functional theory investigation of the solid lanthanum(III) halides

Results from a solid-state ¹³⁹La NMR spectroscopic investigation of the anhydrous lanthanum(III) halides (LaX₃; X=F, Cl, Br, I) at applied magnetic fields of 7.0, 9.4, 11.7, 14.1, and 17.6 T are presented and highlight the advantages of working at high applied magnetic field strengths. The ¹³⁹La quadrupolar coupling constants are found to range from 15.55 to 24.0 MHz for LaCl₃ and LaI₃, respectively. The lanthanum isotropic chemical shifts exhibit an inverse halogen dependence with values ranging from −135 ppm for LaF₃ to 700 ppm for LaI₃, which represents nearly half of the total lanthanum chemical shift range. The spans of the magnetic shielding tensors also vary widely, from 35 to 650 ppm for the solid LaF₃ through LaI₃. DFT calculations of the ¹³⁹La electric field gradient and magnetic shielding tensors have been performed and provide a qualitative interpretation of the trends observed experimentally.