Synthesis Of N,N′-Bis(8-Quinolyl)-Oligo-Methylene-Diamines from 8-Aminoquinolines

Various N′,N-bis(8-quinolyl) trimethylenediamines 3a-3e have been prepared from the corresponding 8-aminoquinolines 1a-1e by direct N-alkylation with 1, 3-dibromopropane in fair yield (25-51%). N. N′-bis(8-quinolyl) ethylenediamines, 3f and 3g, and N,N′-bis(8-(6-methoxyquinolyl) ]tetramethylenediamine. 3h, may only be synthesized in poor yield via the corresponding oxalamides and succinamide.     

Anti‐vibration and vibration isolator performance of poly(styrene‐butadiene‐ styrene)/ester‐type polyurethane thermoplastic elastomers

This investigation presents novel thermoplastic elastomers (TPEs) based on poly(styrene‐butadiene‐styrene) (SBS) and ester‐type polyurethane (TPU‐EX) materials were prepared with varying compositions. A series of investigations were conducted on the relationships between mechanical properties, dynamic mechanical properties, anti‐vibration and vibration isolator properties given, and the different compositions. The experimental results show incompatibilities between SBS and TPU‐EX. SBS mechanical properties, dynamic mechanical properties, anti‐vibration and vibration isolator properties are improved with an increase in the amount of TPU‐EX, suggesting that the blending of SBS with TPU‐EX was consistent with the compound rule. Based on the obtained results, the viscoelasticity of SBS materials, their capacity to isolate vibration, and their anti‐vibration performance can be adjusted by controlling the proportion of TPU‐EX. Copyright © 2009 John Wiley & Sons, Ltd.     

Selective capture of volatile iodine using amorphous molecular organic solids

A simple shape-persistent organic molecular container is capable of selective absorption and storage of I(2(g)) over water vapor and NO gas even in its amorphous solid state. In addition, the strongly associated I(2) can be efficiently released from the charged container in organic solvents under ambient conditions.     

Efficient computer search of large-order multiple recursive pseudo-random number generators

Utilizing some results in number theory, we propose an efficient method to speed up the computer search of large-order maximum-period Multiple Recursive Generators (MRGs). We conduct the computer search and identify many efficient and portable MRGs of order up to 25,013, which have the equi-distribution property in up to 25,013 dimensions and the period lengths up to 10^233,361 approximately. In addition, a theoretical test is adopted to further evaluate and compare these generators. An extensive empirical study shows that these generators behave well when tested with the stringent Crush battery of the test package TestU01.     

Dynamic response of a rotating ball screw subject to a moving regenerative force in grinding

This paper investigates the dynamic response of a rotating ball screw subjected to a moving regenerative force. The rotating ball screw is modeled as a rotating Timoshenko shaft with simply supports. The moving regenerative force describes the nonlinear interactions including the effects of wheel wear, time-delay, and the possibility of contact loss between the grinding wheel head and screw. The assumed mode method together with Runge–Kutta method is employed to analyze the system dynamic response. The total grinding depth is suggested to divide into several passes from rough grinding to fine grinding for obtaining fine surface. The effect of parameters such as the depth of cut and the rotational speeds of grinding wheel and screw are discussed for each pass. The numerical results show that the critical depth of cut depends on the rotational speeds of screw and grinding wheel. If the more the depth of cut is smaller than the critical depth of cut, the earlier the chatter occurs and the faster the vibration grows.     

Defect reduction of laterally regrown GaN on GaN/patterned sapphire substrates

Structural properties of GaN epilayers on wet-etched protruding and recess-patterned sapphire substrates (PSSs) have been investigated in detail using high-resolution double-crystal X-ray diffraction (DCXRD) and etch-pit density methods. The DCXRD results reveal various dislocation configurations on both types of PSSs. The etch pits of GaN on the recess PSS exhibit a regular distribution, i.e. less etch pits or threading dislocation density (TDD) onto the recess area than those onto the sapphire mesas. On the contrary, an irregular distribution is observed for the etch pits of GaN on the protruding PSS. A higher crystal quality of the GaN epilayer grown onto the recess PSS can be achieved as compared with that onto the protruding PSS. These data reflect that the GaN epilayer on the recess PSS could be a better template for the second epitaxial lateral overgrowth (ELOG) of GaN. As a result, the GaN epilayers after the ELOG process display the TDDs of around ∼10⁶ cm⁻².     

Iron oxide nanopropellers prepared by a low-temperature solution approach

The alpha-Fe(2)O(3) (hematite) nanopropellers were synthesized via a low-temperature solution-based method using FeCl(2) as a precursor in the presence of urea and glycine hydrochloride. The formation of alpha-Fe(2)O(3) nanopropellers is strongly depended on the addition of glycine hydrochloride, which serves as a pH modulator and affects the oxidation rate of Fe(2+). The structural evolution of the propeller-structured hematite was found to follow dissolution and recrystallization processes. For the structural conformation, each nanopropeller presents a hexagonal central column closed by six equivalent surfaces of {(-)1100} and the six arrays of the nanopropeller structure are a result of growth along +/- [(-)1100], +/- [(-)1010], and +/-[0(-)110]. Preliminary results show that the magnetic maghemite (gamma-Fe(2)O(3)) nanopropellers could also be prepared by a reduction and reoxidation process from the alpha-Fe(2)O(3) (hematite) nanopropeller precursors.     

Macrocyclic scaffold for the collagen triple helix

[structure: see text] Three strands of natural collagen are linked by covalent bonds prior to their folding into a triple helix. We report on a synthetic collagen in which the strands are pendent on a rigid macrocyclic scaffold of C(3) symmetry. The scaffold confers substantial conformational stability upon the collagen triple helix and makes its folding independent of concentration, both desirable attributes for exploring and exploiting synthetic collagens.     

A Tunable Multicolor Photoluminescent Nanocarbon Prepared from Castor Oil Soot

We herein report a straightforward soot‐based synthesis and characterization of the negatively charged, hydrophilic, photoluminescent nanocarbon. The photoluminescent nanocarbon was prepared by refluxing castor oil soot in nitric acid. The as‐obtained fluorescent nanocarbon shows multiple colors under UV exposure and was characterized with surface morphological and spectral studies. Additionally, the photoluminescence nature of the nanocarbon was tunable by changing the pH or the dilution factor. During the course of the investigation, it has been found that, the photoluminescence nature observed here is not attributed to the presence of poly aromatic hydrocarbons, but solely due to the trait of the fluorescent nanocarbon. These results indicate that interparticle surface plasmon resonance plays a key role in the exhibition of photoluminescence. Furthermore, the feasibility of photoluminescent nanocarbon as a plausible tool for cell imaging and electrochemical application of the oxidized nanocarbon has also been examined.     

An Efficient,Mild and Scalable Synthesis of Bioactive Compounds Containing the Angelicin Scaffold

An efficient, mild and scalable synthesis of angelicin scaffold based compounds was developed. Particularly, the new synthetic route described here circumvents the need for the previously reported key Fries rearrangement step, which uses impractically harsh conditions. The new methodology is applied to the synthesis of several, previously reported analogs of angelicin which have potent anti‐influenza and anti‐cancer activities.