appendix – Supplemental material for Executive Turnover and the Investigation of Former Leaders in New Democracies

Supplemental material, appendix for Executive Turnover and the Investigation of Former Leaders in New Democracies by Donna Bahry and Young Hun Kim in Political Research Quarterly</p

Single-Crystal Structure of a Toluene Sorption Complex of Fully Dehydrated, Fully Mn²⁺-Exchanged Zeolite Y (FAU), |Mn_37.5(C₇H₈)₁₇|[Si₁₁₇Al₇₅O₃₈₄]-FAU

A single crystal of zeolite Y, 0.30 mm in diameter, fully exchanged with Mn2+ and fully dehydrated, was treated with zeolitically dry toluene at 298(1) K and a pressure of 1.3 × 10–4 Pa and evacuated for 2 h. The crystal structure, |Mn37.5(C7H8)17|[Si117Al75O384]-FAU (a = 24.5923(1) Å), was determined by synchrotron X-ray diffraction techniques in the space group Fd3̅m at 100(1) K and was refined to the final error indices R1 = 0.083 and wR2= 0.230. Mn2+ ions occupy sites I, I′, II′, and II with occupancies at 14, 4, 2.5, and 17, respectively. The 17 Mn2+ ions per unit cell at site II each coordinates to three framework oxygen atoms at 2.213(6) Å and extends into the supercage by 0.63 Å from their plane. Each of these Mn2+ ions also interacts facially with a toluene molecule (Mn2+–toluene center = 2.62 Å). The methyl group is somewhat off the plane of the ring, indicative of a net repulsive interaction with the zeolite framework

Single-Crystal Structures of the <i>o</i>-, <i>m</i>-, and <i>p</i>-Xylene Sorption Complexes of Fully Dehydrated, Fully Mn²⁺-Exchanged Zeolite Y (FAU)

Three single crystals of zeolite Y, each 0.3 mm in diameter, fully exchanged with Mn2+ and fully dehydrated, were treated with zeolitically dry o-, m-, and p-xylene, respectively, at 297(1) K, followed by evacuation. Their crystal structures were determined by synchrotron X-ray diffraction techniques in the space group Fd3̅m̅ at 100(1) K and were refined using all intensities to the final error indices R1/wR2 = 0.056/0.160, 0.080/0.217, and 0.066/0.177, respectively. In each structure, Mn2+ ions occupy sites I, I′, II′, and II. In each structure, 18 Mn2+ ions per unit cell at site II (on the 3-fold axes of the single 6-rings) each extend 0.63, 0.68, and 0.67 Å into the supercage to coordinate facially to an o-, m-, and p-xylene molecule, respectively. The corresponding distances from Mn2+ to the centers of the xylene rings are 2.67, 2.65, and 2.63 Å. The methyl groups are all somewhat off the planes of their rings, indicative of a net repulsive interaction with oxygen atoms of the zeolite framework. The hydrogen atoms of the xylene rings all have 3.3 Å interactions with oxygen atoms of the single 6-rings

Hierarchical Nanoflake Surface Driven by Spontaneous Wrinkling of Polyelectrolyte/Metal Complexed Films

A mechanical or physical change observed in nanocomposite thin films has recently offered new opportunities to generate intriguing nanostructures. In this study, we present a novel means of creating a hierarchically developed nanoflake structure by exploiting surface wrinkles that occur during the incorporation process of metallic nanoparticles into layer-by-layer assembled polyelectrolyte multilayer (PEM) thin films. The PEM film composed with linear polyethylenimine (LPEI) and poly(acrylic acid) (PAA) allows for facilitated cationic exchange reaction within the film even after the electrostatic complexation and chemical cross-linking reaction. The subsequent reduction process induces an in situ complexation of metallic nanoparticles with a PEM matrix, causing an accumulation of lateral compressive stress for surface wrinkling. The wrinkling characteristics of the complexed films can be theoretically interpreted by employing the gradationally swollen film model, whereby a gradual change in the elastic property along the axial direction of the film can be appropriately reflected. In addition, wrinkled surfaces are further processed to form vertically aligned and hierarchically ordered nanoflakes after selective removal of the PEM matrix with plasma ashing. Consequently, superhydrophobic surface properties (water contact angle = 170°, sliding angle <1°) can be attained from the hierarchical nanoflake structure. The method presented here is advantageous in that large-scale preparation can be readily implemented by a stepwise dipping process without resorting to specific patterning or a serially applied complex structuring process, which can provide a promising platform technique for various surface engineering applications

Hierarchical Nanoflake Surface Driven by Spontaneous Wrinkling of Polyelectrolyte/Metal Complexed Films

A mechanical or physical change observed in nanocomposite thin films has recently offered new opportunities to generate intriguing nanostructures. In this study, we present a novel means of creating a hierarchically developed nanoflake structure by exploiting surface wrinkles that occur during the incorporation process of metallic nanoparticles into layer-by-layer assembled polyelectrolyte multilayer (PEM) thin films. The PEM film composed with linear polyethylenimine (LPEI) and poly(acrylic acid) (PAA) allows for facilitated cationic exchange reaction within the film even after the electrostatic complexation and chemical cross-linking reaction. The subsequent reduction process induces an <i>in situ</i> complexation of metallic nanoparticles with a PEM matrix, causing an accumulation of lateral compressive stress for surface wrinkling. The wrinkling characteristics of the complexed films can be theoretically interpreted by employing the gradationally swollen film model, whereby a gradual change in the elastic property along the axial direction of the film can be appropriately reflected. In addition, wrinkled surfaces are further processed to form vertically aligned and hierarchically ordered nanoflakes after selective removal of the PEM matrix with plasma ashing. Consequently, superhydrophobic surface properties (water contact angle = 170°, sliding angle <1°) can be attained from the hierarchical nanoflake structure. The method presented here is advantageous in that large-scale preparation can be readily implemented by a stepwise dipping process without resorting to specific patterning or a serially applied complex structuring process, which can provide a promising platform technique for various surface engineering applications

Hydrophobic Nanoparticles Reduce the β‑Sheet Content of SEVI Amyloid Fibrils and Inhibit SEVI-Enhanced HIV Infectivity

Semen-derived enhancer of virus infection (SEVI) fibrils are naturally abundant amyloid aggregates found in semen that facilitate viral attachment and internalization of human immunodeficiency virus (HIV) in cells, thereby increasing the probability of infection. Mature SEVI fibrils are composed of aggregated peptides exhibiting high β-sheet secondary structural characteristics. Herein, we show that polymers containing hydrophobic side chains can interact with SEVI and reduce its β-sheet content by ∼45% compared with the β-sheet content of SEVI in the presence of polymers with hydrophilic side chains, as estimated by polarization modulation-infrared reflectance absorption spectroscopy measurements. A nanoparticle (NP) formulation of this hydrophobic polymer reduced SEVI-mediated HIV infection in TMZ-bl cells by 60% compared with the control treatment. Although these NPs lacked specific amyloid-targeting groups, thus requiring high concentrations to observe biological activity, the use of hydrophobic interactions to alter the secondary structure of amyloids represents a useful approach to neutralizing the SEVI function. These results could, therefore, have general implications in the design of novel materials that can modify the activity of amyloids associated with a variety of other neurological and systemic diseases

Amyloid β Ion Channels in a Membrane Comprising Brain Total Lipid Extracts

Amyloid β (Aβ) oligomers are the predominant toxic species in the pathology of Alzheimer’s disease. The prevailing mechanism for toxicity by Aβ oligomers includes ionic homeostasis destabilization in neuronal cells by forming ion channels. These channel structures have been previously studied in model lipid bilayers. In order to gain further insight into the interaction of Aβ oligomers with natural membrane compositions, we have examined the structures and conductivities of Aβ oligomers in a membrane composed of brain total lipid extract (BTLE). We utilized two complementary techniques: atomic force microscopy (AFM) and black lipid membrane (BLM) electrical recording. Our results indicate that Aβ_1–42 forms ion channel structures in BTLE membranes, accompanied by a heterogeneous population of ionic current fluctuations. Notably, the observed current events generated by Aβ_1–42 peptides in BTLE membranes possess different characteristics compared to current events generated by the presence of Aβ_1–42 in model membranes comprising a 1:1 mixture of DOPS and POPE lipids. Oligomers of the truncated Aβ fragment Aβ_17–42 (p3) exhibited similar ion conductivity behavior as Aβ_1–42 in BTLE membranes. However, the observed macroscopic ion flux across the BTLE membranes induced by Aβ_1–42 pores was larger than for p3 pores. Our analysis of structure and conductance of oligomeric Aβ pores in a natural lipid membrane closely mimics the in vivo cellular environment suggesting that Aβ pores could potentially accelerate the loss of ionic homeostasis and cellular abnormalities. Hence, these pore structures may serve as a target for drug development and therapeutic strategies for AD treatment

Synthesis and Self-Assembly of Poly(vinylpyridine)-Containing Brush Block Copolymers: Combined Synthesis of Grafting-Through and Grafting-to Approaches

Synthesis of brush block copolymers (brush BCPs) enables the generation of BCPs with various block compositions and chain architectures, which determine the morphologies and functionalities of the polymeric materials. Here, we report a synthetic strategy for preparing structurally diverse brush BCPs via combined synthesis of the grafting-through and grafting-to approach. The polystyrene-based brush copolymer with an azide functionality is synthesized by sequential ring-opening metathesis polymerization of norbornene-based macromonomers, followed by post-polymerization modification. The final brush BCPs are then prepared by grafting various side chain polymers [poly­(2-vinylpyridine), poly­(4-vinylpyridine), or poly­(dimethylsiloxane)] onto the precursor BCPs with the desired ratio between the azido group on the backbone and alkynyl side chain polymer. This synthetic method is versatile in producing brush BCPs with various side chain types, backbone lengths, and grafting densities. In particular, it is observed that the morphologies of the brush BCPs can be controlled from lamella to cylinders to spheres by tuning the grafting densities. Furthermore, this interesting transition of self-assembled morphologies of the brush BCPs at different grafting densities is elucidated by the simulation results

Demographics and clinical characteristics.

Demographics and clinical characteristics.</p

Example for autumn protocol.

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