This study is the first quantitative synchrotron grazing incidence X-ray scattering investigation of nanoscale film morphologies of tricyclic block copolymers based on poly(n-decyl glycidyl ether) ...(PDGE) and poly(2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) (PTEGGE) blocks in equivalent volume fractions. Both PDGE and PTEGGE blocks of the tricyclic block copolymers are amorphous, but copolymers exhibit phase-separated lamellar nanostructures due to block immiscibility. The lamellar structures vary in their structural parameters such as lamellar orientation and structural integrity stability depending on the degree of topological confinement effect taking effect. Interestingly, sub-10 nm domain spacings are established by all nanostructures, which are remarkably shorter than that of the linear analogue. These exceptionally short domain spacings are evident that the tricyclic block copolymer approach is highly efficient for developing high-performance nanolithographic materials for future advanced semiconductor applications.
This study provides first insights into the micellization behavior and micellar morphologies of bicyclic amphiphiles in four different topologies: bicy-BCP-A, bicy-BCP-B, bicy-BCP-C, and bicy-BCP-D, ...consisting of poly(n-decyl glycidyl ether) and poly(2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) blocks in equivalent molar fractions. Quantitative synchrotron X-ray scattering analysis reveals that all bicyclic amphiphiles self-assemble into unimodal nanomicelles consisting of core, dense corona, and soft corona structural components. The micelles also demonstrate substantial size reductions (56.7–70.7%) compared to micelles of their linear counterpart (l-BCP). The critical micelle concentration, stability, and structural parameters (shape, size, and others) of nanomicelles are differentiated by controlling the bicyclic topology types. bicy-BCP-A, -B, and -C form oblate ellipsoidal micelles, whereas bicy-BCP-D and l-BCP assemble into prolate ellipsoidal micelles. The size is found to be in the following order: bicy-BCP-D < bicy-BCP-C < bicy-BCP-B < bicy-BCP-A ≪ l-BCP. Furthermore, the structural stability is in the following order: l-BCP < bicy-BCP-D ≪ bicy-BCP-B < bicy-BCP-C < bicy-BCP-A. These results indicate that the topology-controlled bicyclic block copolymers can be used as a desirable platform for developing high-performance functional core–shell nanoparticles for advanced applications in various fields, including smart drug delivery, biomedical imaging, cosmetics, advanced coating appliances, and molecular electronics.
Photodissociation of HABI to radicals.
Dynamics of the photodissociation process of a hexaarylbiimidazole derivative, 2,2′-di(
ortho-chlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole (
o-Cl-HABI), in ...benzene solution was investigated by means of the femtosecond–nanosecond laser spectroscopy. The time evolution of the transient absorption of the lophyl radical, the product of the photodissociation, was biphasic with the faster and the slower time constants of 80
fs and 1.9
ps, respectively. The faster time constant was ascribable to the formation of the lophyl radical through the bond fission after the excitation, and the slower time constant may be attributed to the conformational change and/or vibrational cooling of nascent radicals.
BCR/ABL tyrosine kinase generated from the chromosomal translocation t(9;22) causes chronic myelogenous leukemia and acute lymphoblastic leukemia. To examine the roles of BCR/ABL-activated individual ...signaling molecules and their cooperation in leukemogenesis, we inducibly expressed a dominant negative (DN) form of Ras, phosphatidylinositol 3-kinase, and STAT5 alone or in combination in p210 BCR/ABL-positive K562 cells. The inducibly expressed DN Ras (N17), STAT5 (694F), and DN phosphatidylinositol 3-kinase (Δp85) inhibited the growth by 90, 55, and 40%, respectively. During the growth inhibition, the expression of cyclin D2 and cyclin D3 was suppressed by N17, 694F, or Δp85; that of cyclin E by N17; and that of cyclin A by Δp85. In addition, N17 induced apoptosis in a small proportion of K562, whereas 694F and Δp85 were hardly effective. In contrast, coexpression of two DN mutants in any combinations induced severe apoptosis. During these cultures, the expression of Bcl-2 was suppressed by N17, 694F, or Δp85, and that of Bcl-XL by N17. Furthermore, although K562 was resistant to interferon-α- and dexamethasone-induced apoptosis, disruption of one pathway by N17, 694F, or Δp85 sensitized K562 to these reagents. These results suggested that cooperation among these molecules is required for full leukemogenic activities of BCR/ABL.
A comprehensive set of amphiphilic star-shaped block copolyethers with a fixed molecular weight and composition was synthesized via the t-Bu-P4-catalyzed ring-opening polymerization (ROP) of ...2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether as a hydrophilic monomer and decyl glycidyl ether as a hydrophobic monomer. The three- and four-armed star-block copolyethers, i.e., the (AB)3-, (BA)3-, (AB)4-, and (BA)4-type star-block copolyethers, where A and B represent hydrophilic and hydrophobic blocks, respectively, were synthesized by the sequential t-Bu-P4-catalyzed block copolymerization using tri- and tetra-alcohol initiators, respectively, according to the core-first method. The homogeneous growth of each arm was confirmed by cleaving the linkages between the initiator residue and polyether arms. The synthesis of the A2B2-, AB2-, and A2B-type miktoarm star copolyethers was achieved by the combination of the t-Bu-P4-catalyzed ROP and azido-alkyne click chemistry. The azido- and ethynyl-functionalized precursor polyethers with the predicted molecular weights were separately prepared by the t-Bu-P4-catalyzed ROP with the aid of functional initiators as well as a terminator. The intermolecular click reaction of the precursors provided the desired miktoarm star copolyethers. All the obtained star-shaped block copolyethers had a comparable monomer composition (degree of polymerization = 50:50) and total molecular weight (ca. 22 200 g mol–1) with a narrow dispersity (<1.05). The hydrodynamic diameter and the cloud point analyses for the aqueous micellar solution of the amphiphilic star-shaped block copolyethers revealed that the self-assembly properties were affected by the block arrangements and branched architectures of the amphiphilic polymers.
This protocol is used for the detection of immunoglobulin heavy (H) chain rearrangements. This PCR-based assay enables detection of DH-JH recombination in cultured hematopoietic cells (Schlissel et ...al., 1991; Satoh et al., 2013) e.g. ES-derived cells (Satoh et al., 2013).
Global impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. ...Here we test, for the first time, systematically across many important systems, how well such impact models capture the impacts of extreme climate conditions. Using the 2003 European heat wave and drought as a historical analogue for comparable events in the future, we find that a majority of models underestimate the extremeness of impacts in important sectors such as agriculture, terrestrial ecosystems, and heat-related human mortality, while impacts on water resources and hydropower are overestimated in some river basins; and the spread across models is often large. This has important implications for economic assessments of climate change impacts that rely on these models. It also means that societal risks from future extreme events may be greater than previously thought.
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