An efficient microwave-assisted Suzuki reaction using Pd/MCM-41 and Pd/SBA-15 as catalysts in solvent-free condition

Palladium catalysts, Pd/MCM-41 and Pd/SBA-15 were prepared by impregnation of an aqueous solution of [Pd(NH₃)₄]Cl₂ on MCM-41 and SBA-15. Palladium contents of Pd/MCM-41 and Pd/SBA-15 are 8.4% and 8.7%, respectively. It has been shown that these catalysts are very suitable to microwave-assisted Suzuki reactions under solvent-free condition. It is also found that the base additives for this reaction are K₂CO₃, Cs₂CO₃ or CsF. Thus, phenylboronic acid and phenyl iodide with Pd/MCM-41 produce biphenyl by microwave irradiation for 10 min in 97.4% yield. Phenyl bromide, instead of phenyl iodide, also proceeds the reaction with phenylboronic acid using Pd/MCM-41 or Pd/SBA-15 yielding biphenyl by microwave irradiation for 10 min in excellent yield. Whereas the reaction of phenyl chloride with phenylboronic acid gives poor yield in same condition. Various aryl iodides and aryl bromides are tested. In this paper our recent results of microwave-assisted Suzuki reaction using Pd/MCM-41 and Pd/SBA-15 under solvent-free condition are described.     

Exploring the effect of dual use on the value of military technology patents based on the renewal decision

Concerns regarding the high level of research and development (R&D) expenditure on military technology have prompted many nations to pursue a dual-use regime in military R&D. However, the value of dual-use military technology has not yet been quantitatively investigated. We explore whether military technology with a higher level of duality has been more valuable than that with a lower level of duality. We assume that the patent of valuable military technology was renewed until its termination. We retrieve military patents from the United States Patent and Trademark Office during 1976–2014 based on their International Patent Classification (IPC) as F41 or F42. Then, we propose three indicators to assess the duality level of them. The first indicator is based on the determination of whether the patented technology is utilizable in both the military and the civilian sectors using its IPC. For the second indicator, we estimate the potential of convergence of a patented technology with various technological fields using the degree of centrality of the IPC’s co-occurrence network. The third indicator is based on ratio of forward citation by the civilian sector over the total number of forward citations as a measurement of technology diffusion toward the civilian sector. Using logistic regression, we found that the first two indicators are positively associated with patent renewal decision, while the last indicator is nonsignificant. The effects of the two significant indicators suggests that military technologies are more valuable when the technology itself can be used in various sectors, including the civilian sector, and can be converged with technologies in different fields. However, the nonsignificant influence of the third variable suggests that the relation between patent value and diffusion effects toward following inventions is not confined to the civilian sector. Our findings provide evidence of the impact of dual-use policies in military R&D.     

Linear prediction approach to oversampling parameter estimation for multiple complex sinusoids

The problem of oversampling parameter estimation for noisy sinusoidal signals is addressed. We first extend the weighted least squares (WLS) approach to the complex sinusoids. Then the oversampling weighted least squares (OSWLS) estimator is proposed based on data decimation. Estimation performance of the OSWLS method is analyzed via theoretical and simulation studies. Results are also compared to those of the WLS and decimative unitary ESPRIT methods as well as Cramér-Rao lower bound.     

Disparities in exploitative and exploratory patenting performance across regions: Focusing on the roles of agglomeration externalities

We try to identify the determinants of regional variation in both exploitative and exploratory innovative competencies. Hereby, we focus on how a knowledge-creation mechanism with specialized externalities differs from one with diversified externalities. Innovative competence in the US is measured by local patenting performance; exploitative and exploratory patenting performances are distinguished by the degree of backward citation. Based on the extended knowledge-production function, including the two agglomeration externalities, our findings show that specialized externalities are associated with exploitation, while diversified externalities are positively related with both exploration and exploitation, regardless of industrial sectors.     

Transition between two solid-solutions: Effective and easy way for fine Ce1−xGdxO2−x/2 powders preparation

Ceria, pure or doped, is an important electrolyte material in solid oxide fuel cells, catalysts, and plutonium surrogates. Even though ceria is a widely studied material, its coprecipitation with the most common doping element, gadolinium, remains mostly overlooked. Here, we present a comprehensive study of gadolinium–cerium oxalates prepared by coprecipitation of gadolinium (III) and cerium (III) salts by oxalic acid under different reaction conditions and element ratios. For this purpose, we assessed the effects of basic precipitation conditions on the final oxalate size, shape, and conversion into the corresponding oxides. The results showed that coprecipitation with oxalic acid yields and ideal solid solution, which translates into the oxides. This low-cost and straightforward synthetic route provides then high-quality solid solutions of Ge–Gd in the oxide lattice. Thus, this approach has a high industrialization potential, with significant advantages over hydrolysis or hydrothermal techniques.     

Biomineralized hyaluronic acid/poly(vinylphosphonic acid) hydrogel for bone tissue regeneration

Novel biomineralized hydrogels composed of hyaluronic acid (HA) and vinyl phosphonic acid (VPAc) were designed with the aim of developing a biomimetic hydrogel system to improve bone regeneration by local delivery of a protein drug including bone morphogenetic proteins. We synthesized crosslinked hydrogels composed of methacrylated HA and poly(VPAc) [P(VPAc)], which serves as a binding site for calcium ions during the mineralization process. The HA/P(VPAc) hydrogels were biomineralized by a urea‐mediation method to create functional polymer hydrogels that can deliver the protein drug and mimic the bone extracellular matrix. The water content of the hydrogels was influenced by the HA/P(VPAc) composition, crosslinking density, biomineralization, and ionic strength of the swelling media. All HA/P(VPAc) hydrogels maintained more than 84% water content. Enzymatic degradation of HA/P(VPAc) hydrogels was dependent on the concentration of hyaluronidase and the crosslinking density of the polymer network within the hydrogel. In addition, the release behavior of bovine serum albumin from the HA/PVPAc hydrogels was mainly influenced by the drug loading content, water content, and biomineralization of the hydrogels. In a cytotoxicity study, the HA/P(VPAc) and biomineralized HA/P(VPAc) hydrogels did not significantly affect cell viability. These results suggest that biomineralized HA/P(VPAc) hydrogels can be tailored to create a biomimetic hydrogel system that promotes bone tissue repair and regeneration by local delivery of protein drugs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41194.     

Polystyrene-poly(2-ethylhexylmethacrylate) block copolymers: Synthesis,bulk phase behavior,and thin film structure

Anionic polymerization was employed to synthesize well-defined diblock copolymers of polystyrene and poly(2-ethylhexylmethacrylate), PS-PEHMA. Diblock morphologies in bulk and in substrate-supported thin films were characterized by small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), respectively. PS-PEHMA diblocks exhibited thermotropic order-disorder transitions; one diblock showed a thermoreversible transition between lamellae and a higher-temperature morphology assigned as perforated lamellae. Unlike PS-poly(alkylmethacrylate) diblocks where the alkyl group is n-butyl or n-pentyl, PS-PEHMA diblocks showed a typical decreasing Flory interaction parameter with increasing temperature. Thin films of PS-cylinder-forming PS-PEHMA diblocks showed a strong preference for the cylinders to lie in the plane of the film; films of incommensurate thickness readily formed terraces. Films of commensurate thickness were easily aligned over macroscopic areas through the application of mechanical shear.