IsoCombretaQuinazolines: Potent Cytotoxic Agents with Antitubulin Activity

A series of novel isocombretaquinazolines (isoCoQ) 4 were quickly prepared by coupling N‐toluenesulfonylhydrazones with 4‐chloroquinazolines under palladium catalysis. These compounds, which can be regarded as isocombretastatin A‐4 (isoCA‐4) analogues that lack the 3,4,5‐trimethoxyphenyl ring, displayed nanomolar‐level cytotoxicity against various human cancer cell lines and were observed to effectively inhibit tubulin polymerization. The isoCoQ compounds 2‐methoxy‐5‐(1‐(2‐methylquinazolin‐4‐yl)vinyl)phenol ( 4 b ), 4‐[1‐(3‐fluoro‐4‐methoxyphenyl)vinyl]‐2‐methylquinazoline ( 4 c ), and 2‐methoxy‐5‐(1‐(2‐methylquinazolin‐4‐yl)vinyl)aniline ( 4 d ), which respectively bear the greatest resemblance to isoCA‐4, isoFCA‐4, and isoNH₂CA‐4, are able to arrest HCT116 cancer cells in the G₂/M cell‐cycle phase at very low concentrations. Preliminary in vitro antivascular assay results show that 4 d is able to disrupt a network of capillary‐like structures formed by human umbilical vein endothelial cells on Matrigel. All these results clearly demonstrate that replacement of the 3,4,5‐trimethoxyphenyl ring of isoCA‐4 with a quinazoline nucleus is a feasible approach toward new and highly promising derivatives with the potential for further development as antitubulin agents.     

Preparation and Characterization of Sustainable Polyurethane Foams from Soybean Oils

Polyol derived from soybean oil was made from crude soybean oil by epoxidization and hydroxylation. Soy-based polyurethane (PU) foams were prepared by the in-situ reaction of methylene diphenyl diisocyanate (MDI) polyurea prepolymer and soy-based polyol. A free-rise method was developed to prepare the sustainable PU foams for use in automotive and bedding cushions. In this study, three petroleum-based PU foams were compared with two soy-based PU foams in terms of their foam characterizations and properties. Soy-based PU foams were made with soy-based polyols with different hydroxyl values. Soy-based PU foams had higher T _g (glass transition temperature) and worse cryogenic properties than petroleum-based PU foams. Bio-foams had lower thermal degradation temperatures in the urethane degradation due to natural molecular chains with lower thermal stability than petroleum skeletons. However, these foams had good thermal degradation at a high temperature stage because of MDI polyurea prepolymer, which had superior thermal stability than toluene diisocyanate adducts in petroleum-based PU foams. In addition, soy-based polyol, with high hydroxyl value, contributed PU foam with superior tensile and higher elongation, but lower compressive strength and modulus. Nonetheless, bio-foam made with high hydroxyl valued soy-based polyol had smaller and better distributed cell size than that using low hydroxyl soy-based polyol. Soy-based polyol with high hydroxyl value also contributed the bio-foam with thinner cell walls compared to that with low hydroxyl value, whereas, petroleum-based PU foams had no variations in cell thickness and cell distributions.     

Selectivity control in electron spin inversion processes: regio- and stereochemistry of Paternò-Büchi photocycloadditions as a powerful tool for mapping intersystem crossing processes

Regio- and stereoselectivity in ene-carbonyl photocycloadditions depend on the spin multiplicity of the excited carbonyl state, although both singlet and triplet states produce the cycloadducts with comparable chemoselectivity. The correlation between selectivity and spin state was evaluated by concentration, temperature, and solvent viscosity studies. The higher selectivity observed for triplet reactions is rationalized by the optimal conformations of the intermediate 2-oxabutane-1,4-diyls for intersystem crossing (ISC) to the singlet manifold, controlled preferentially by spin-orbit coupling. This weak interaction connected with ISC can lead to substantial control of regio- and stereoselectivity. The role of hyperfine coupling is demonstrated by magnetic isotope effects.     

Perfluoroalkylated fatty acid monoesters of trehalose and sucrose for biomedical applications: Remarkable emulsifying properties of 6-O-[3′-(perfluorooctyl) propanoyl]-trehalose

A new series of perfluoroalkylated fatty acid monoesters of α,α-trehalose and sucrose has been evaluated with respect to their physicochemical and biological properties for possible biomedical use. These water-soluble compounds strongly reduce the water surface tension and fluorocarbon/water interfacial tension. As co-surfactants in perfluorodecalin/Pluronic F-68 type emulsions they significantly increase the stability of these emulsions. Remarkably stable concentrated perfluorodecalin-in-water (50% w/v) emulsions were obtained when the C₈F₁₇CH₂CH₂C(O)-α,α-trehalose monoester was used as the sole surfactant, while no emulsion could be obtained with its maltoside analogue. No significant effect on the growth and viability of Namalva cell cultures and no hemolytic activity on human erythrocytes at concentrations up to 50 g/L were detected for these amphiphiles in spite of their high surface activity. The LD₅₀ was found to be in the range of 250–375 mg/kg of body weighti.v. in mice.     

The mechanical and thermal properties of graphitic carbon nitride (g-C3N4)-based epoxy composites

Numerous ways to reinforce epoxy resin and improve its thermomechanical properties have been attempted using organic and inorganic nanoparticles. In this paper, graphitic carbon nitride (g-C₃N₄) nanoparticles were synthesized and used to improve the mechanical properties and thermal stability of epoxy composites. The g-C₃N₄ was synthesized from cheap melamine powder using a simple one-step thermal treatment, then was used to reinforce the resin at different weight percentages (wt%). X-ray diffraction, scanning electron microscopy (SEM), and Fourier infrared spectroscopy were used to characterize the g-C₃N₄ and ensure its successful synthesis by studying the changes in its crystal structure, morphology, and chemical structure. The filler was dispersed in the resin using a combination of ultrasonication and high shear mixing. The results showed that the mechanical properties were optimum when 0.5 wt% g-C₃N₄ was used. The tensile strength and fracture toughness of the resulting epoxy composite improved by 21.8% and 77.3%, respectively. SEM was used to investigate the morphologies of cracks formed in epoxy composite specimens after the tensile testing. The SEM micrographs of the fracture surface showed a transition from a brittle to a rough morphology, signifying the enhancement in the composites' toughness. Thermogravimetric analysis showed a good improvement in degradation temperature of up to 8.86% while dynamic mechanical analysis showed that the incorporation of g-C₃N₄ did not affect the material's glass transition temperature.     

High precision linear slide. Part I: design and construction

The purpose of the linear slide project was to gain knowledge and experience in high precision machine design dedicated to short stroke single and multiple axes. The work presented is part of a research program developed by the Université de Technologie de Compiègne to design a high precision linear slide.This paper discusses the design and construction of a linear stage with 16 nm positioning precision. A steel slide with a mass of 100 kg is fully floated by three hydrostatic bearings. The working motion length of the system is 220 mm. Very high axis stiffnesses are achieved.The linear axis is driven with a maximal translational speed of 10 mm/s using a friction drive actuator. A closed loop servo position control i.e. Internal Model Controller (IMC) is used to compensate automatically for unmodeled mechanical behaviors such as prerolling phenomena. The metrology frame including laser interferometer and optic linear encoder was used for the measurements.     

Fumigant and Contact Toxicities of Monoterpenes to <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> (L.) and <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Herbst) and their Inhibitory Effects on Acetylcholinesterase Activity

A comparative study was conducted to assess the contact and fumigant toxicities of eleven monoterpenes on two important stored products insects—, Sitophilus oryzae, the rice weevil, and Tribolium castaneum, the rust red flour beetle. The monoterpenes included: camphene, (+)-camphor, (−)-carvone, 1-8-cineole, cuminaldehyde, (l)-fenchone, geraniol, (−)-limonene, (−)-linalool, (−)-menthol, and myrcene. The inhibitory effect of these compounds on acetylcholinesterase (AChE) activity also was examined to explore their possible mode(s) of toxic action. Although most of the compounds were toxic to S. oryzae and T. castaneum, their toxicity varied with insect species and with the bioassay test. In contact toxicity assays, (−)-carvone, geraniol, and cuminaldehyde showed the highest toxicity against S. oryzae with LC₅₀ values of 28.17, 28.76, and 42.08 μg/cm², respectively. (−)-Carvone (LC₅₀ = 19.80 μg/cm²) was the most effective compound against T. castaneum, followed by cuminaldehyde (LC₅₀ = 32.59 μg/cm²). In contrast, camphene, (+)-camphor, 1-8-cineole, and myrcene had weak activity against both insects (i.e., LC₅₀ values above 500 μg/cm²). In fumigant toxicity assays, 1-8-cineole was the most effective against S. oryzae and T. castaneum (LC₅₀ = 14.19 and 17.16 mg/l, respectively). Structure-toxicity investigations revealed that (−)-carvone—, a ketone—, had the highest contact toxicity against the both insects. 1-8-Cineole—, an ether—, was the most potent fumigant against both insects. In vitro inhibition studies of AChE from adults of S. oryzae showed that cuminaldehyde most effectively inhibited enzyme activity at the two tested concentrations (0.01 and 0.05 M) followed by 1-8-cineole, (−)-limonene, and (l)-fenchone. 1-8-Cineole was the most potent inhibitor of AChE activity from T. castaneum larvae followed by (−)-carvone and (−)-limonene. The results of the present study indicate that (−)-carvone, 1,8-cineole, cuminaldehyde, (l)-fenchone, and (−)-limonene could be effective biocontrol agents against S. oryzae and T. castaneum.     

Wear characteristics of styrene butadiene rubber/natural rubber blends with varying carbon blacks by DIN abrader and mining rock surfaces

In this study, nine rubber compounds were produced by varying the proportions of natural rubber (NR), styrene butadiene rubber (SBR), and four different carbon blacks. Tensile and tear properties are enhanced by the addition of intermediate super abrasion furnace (ISAF) N231, and modulus increases for the compounds containing N234 carbon blacks. The wear behavior of the prepared rubber vulcanizates against various rocks, such as, granite, shale, schist, sandstone, coal, and concrete, at 4.4 N normal load and 0.8 m/s relative sliding speed were studied in a specially fabricated experimental setup. The DIN abrasion testing results show good abrasion resistant properties of 70 phr NR and 30 phr SBR with N231 grade ISAF type carbon black. Also, moderate abrasion resistance is found in rubber compound containing 80 phr NR and 20 phr SBR with N234 grade ISAF type of carbon black. Out of the various rock types, the schist and sandstone are observed to be highly abrasive against the prepared rubber compounds. The microscopic examination of the abraded rubber surfaces has indicated the formation of longitudinal grooves against harder rocks and transverse ridges against softer rocks. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recovery and Amino Acid Composition of Protein Precipitates Isolated from Rice Starch Processing Liquors

Precipitates containing 47.7% and 30.5% protein were isolated from rice starch steep and sorter liquors respectively by pH adjustment of these liquors. The pH for protein precipitation from the steep liquor was 7.0 and from the sorter liquor was 5.0. The acid hydrolysates of both precipitates contained at least seventeen amino acids, Glutamic acid and arginine constitute the largest proportions of these acids. Nine essential amino acids were found to be present in variable amounts. The industrial application of this method for the preparation of protein precipitates is discussed.