Support-free robust topology optimization based on pseudo-inverse stiffness matrix and eigenvalue analysis

Structural and Multidisciplinary Optimization - Current finite element analysis (FEA) and optimizations require boundary conditions, i.e., constrained nodes. These nodes represent structural...     

Chemical and Physical Properties of Capped and Uncapped Alkylthio Substituted Tetrathiafulvalenes and Their Charge Transfer Complexes

A series of tetrakis(n-alkylthio)tetrathiafulvalene (alkyl-methyl to octadecyl; TTC_n-TTF (n = 1-18) has been synthesized. Synthesis, structure, and some physical properties of these uncapped analogues of bis(ethylenedithiolo)tetrathiafulvalene (BEDT-TTF) are described and compared with those of BEDT-TTF. Several charge transfer complexes of TTC₁-TTF are presented in terms of their electrical conductivities, ionicity, structures, and intermolecular interactions and compared with those of BEDT-TTF compounds. Molecular conformation, mode of the sulfur-to-sulfur atomic contacts, and requirements for an organic metal are discussed from the viewpoint of the molecular design.     

Microwave Assisted Synthesis of Organic-Inorganic Polymer Hybrids

Summary Organic-inorganic polymer hybrids from various organic polymers such as poly(ethylene oxide) and poly(N-vinylpyrrolidone) were prepared with the assistance of microwave heating. With the 500 W, 2.45 GHz of microwave irradiation, the formation of polymer hybrids was accelerated. The obtained polymer hybrids were optically transparent and no phase separation was observed. From the SEM images and IR spectra of the obtained polymer hybrids, the composition and the properties of the polymer hybrids synthesized with microwave heating were found to be mostly the same as that synthesized with conventional heating.     

Fc-Binding Antibody-Recruiting Molecules Targeting Prostate-Specific Membrane Antigen: Defucosylation of Antibody for Efficacy Improvement**

Synthetic small molecules that redirect endogenous antibodies to target cells are promising drug candidates because they overcome the potential shortcomings of therapeutic antibodies, such as immunogenicity and the need for intravenous delivery. Previously, we reported a novel class of bispecific molecules targeting the antibody Fc region and folate receptor, named Fc-binding antibody-recruiting molecules (Fc-ARMs). Fc-ARMs can theoretically recruit most endogenous antibodies, inducing antibody-dependent cell-mediated cytotoxicity (ADCC) to eliminate cancer cells. Herein, we describe new Fc-ARMs that target prostate cancer (Fc-ARM-Ps). Fc-ARM-Ps recruited antibodies to cancer cells expressing prostate-specific membrane antigen but did so with lower efficiency compared with Fc-ARMs targeting the folate receptor. Upon recruitment by Fc-ARM-P, defucosylated antibodies efficiently activated natural killer cells and induced ADCC, whereas antibodies with intact N-glycans did not. The results suggest that the affinity between recruited antibodies and CD16a, a type of Fc receptor expressed on immune cells, could be a key factor controlling immune activation in the Fc-ARM strategy.     

Synthesis of novel π-conjugated boron polymers containing transition metal in the main chain and their optical properties

Summary Novel π-conjugated boron polymers containing transition metals in the main chain were prepared by hydroboration polymerization between tetrayne monomer including metal complex and tripylborane. From gel permeation chromatographic analysis (THF, PSt standards), the number-average molecular weights of the polymers obtained were found to be 9,000. The polymers were soluble in common organic solvents such as THF, chloroform and benzene. The absorption peaks due to π-π^* transition were observed around 390nm in the UV-vis spectra of these polymers. The fluorescence emission spectra exhibited intense peaks at 490nm (in chloroform, room temperature, excitation wavelength at 390nm). Received: 16 April 2001/Accepted: 27 April 2001     

Thermoelectric Properties of Icosahedral Al-Pd-(Mn or Re) Quasicrystals: Improvement of the <Emphasis Type=Italic>ZT</Emphasis> Value by Ga Substitution for Al Atoms

We report the thermoelectric properties of polygrain icosahedral Al₇₁Pd₂₀Mn₉ and Al₇₁Pd₂₀Re₉ quasicrystals (QCs). The microstructure of polygrain (arc-melted and annealed) Al-Pd-Re QCs is highly porous. We synthesized sintered pellets of the Al₇₁Pd₂₀Re₉ QC by the spark plasma sintering (SPS) method, resulting in an improvement in their relative density from 65% to more than 99%. This enables direct comparison of Al₇₁Pd₂₀Mn₉ QCs with Al₇₁Pd₂₀Re₉ QCs. The maximum dimensionless figures of merit ZT were 0.18 and 0.12 for Al₇₁Pd₂₀Mn₉ and Al₇₁Pd₂₀Re₉ QCs, respectively. For further improvement of the ZT value, we substituted Ga for Al atoms in the Al₇₁Pd₂₀Mn₉ QC in accordance with the guiding principle of weakly bonded rigid heavy clusters (WBRHCs). The sound velocity and Debye temperature beneficially decreased with increasing Ga concentration, indicating weakening of the intercluster bond strength, as predicted for WBRHCs. The maximum ZT value was increased by a factor of 1.4 from 0.18 for the Al₇₁Pd₂₀Mn₉ QC to 0.26 for the Al₆₈Ga₃Pd₂₀Mn₉ QC by the addition of an alloying effect to that of the WBRHCs.     

Effect of introduction of chondroitin sulfate into polymer-peptide conjugate responding to intracellular signals

We recently developed a novel tumor-targeted gene delivery system responding to hyperactivated intracellular signals. Polymeric carrier for gene delivery consists of hydrophilic neutral polymer as main chains and cationic peptide substrate for target enzyme as side chains, and was named polymer-peptide conjugate (PPC). Introduction of chondroitin sulfate (CS), which induces receptor-medicated endocytosis, into polymers mainly with a high cationic charge density such as polyethylenimine can increase tumor-targeted gene delivery. In the present study, we examined whether introduction of CS into PPC containing five cationic amino acids can increase gene expression in tumor cells. Size and zeta potential of plasmid DNA (pDNA)/PPC/CS complex were <200 nm and between -10 and -15 mV, respectively. In tumor cell experiments, pDNA/PPC/CS complex showed lower stability and gene regulation, compared with that of pDNA/PPC. Moreover, no difference in gene expression was identified between positive and negative polymer. These results were caused by fast disintegration of pDNA/PPC/CS complexes in the presence of serum. Thus, we suggest that introduction of negatively charged CS into polymers with a low charge density may lead to low stability and gene regulation of complexes.