Heterocyclic quinones. VIII. Synthesis and spectra of new carbazoloquinone derivatives of naturally occurring amino acids

Fifteen naturally occurring amino acids representing basic, neutral and acidic members were interacted with 4,4′-dimethoxydiquinone (I). Basic amino acids reacted readily to give amino acid substituted carbazoloquinones (III), while neutral and acidic amino acids reacted only after addition of an acid binding agent. Using an excess of any of the amino acids resulted in the substitution of the quinonoid methoxyl group in compounds (III) by an amino acid moiety. In the case of basic amino acids, this substitution reaction was preferentially influenced by a terminal amino or guanidino amino rather than by an α-amino group. Moreover, basic amino acids could be reacted with two moles of (I) to produce dicarbazoloquinones (X). The i.r. and u.v.-visible spectra of the various carbazoloquinone products were determined and discussed.     

Chemical studies on corn embryos infected by various fungi

The occurrence of various fungi in corn kernels obtained from eight localities in Egypt in two successive years was studied. Values for refractive index, color, acid value, saponification value, iodine value, peroxide value and unsaponifiable matter content of oils extracted from corn embryos that were deliberately infected by various fungi were compared to those for oil extracted from healthy embryos. Spectrometric analyses (UV, visible and IR) were done to deduce differences in the functional groups of the oils. Corn oil extracted from embryos infected with various fungi contained the same lipid classes as the oil extracted from healthy embryos. Contents of mono- and diglycerides and free fatty acids were much smaller for the oil extracted from healthy embryos. The fatty acid and unsaponifiable compositions of oils were studied by gas liquid chromatography. The fatty acid composition of corn oil extracted from infected embryos showed that some new and short-chain fatty acids had appeared and that some of the 18:2 was converted to 18:0. Analysis of the hydrocarbon fraction of the unsaponifiables showed also that some new compounds had appeared and others disappeared. The sterols were greatly influenced by the fungi and the ratio between different sterols might be used to characterize the effect of fungi. Aflatoxin B₁ content of oil extracted from corn embryos infected byA. flavus was 300 μg/kg.     

Effect of phosphate-based glass fibre surface properties on thermally produced poly(lactic acid) matrix composites

Incorporation of soluble bioactive glass fibres into biodegradable polymers is an interesting approach for bone repair and regeneration. However, the glass composition and its surface properties significantly affect the nature of the fibre-matrix interface and composite properties. Herein, the effect of Si and Fe on the surface properties of calcium containing phosphate based glasses (PGs) in the system (50P₂O₅-40CaO-(10-x)SiO₂-xFe₂O₃, where x = 0, 5 and 10 mol.%) were investigated. Contact angle measurements revealed a higher surface energy, and surface polarity as well as increased hydrophilicity for Si doped PG which may account for the presence of surface hydroxyl groups. Two PG formulations, 50P₂O₅-40CaO-10Fe₂O₃ (Fe10) and 50P₂O₅-40CaO-5Fe₂O₃-5SiO₂ (Fe5Si5), were melt drawn into fibres and randomly incorporated into poly(lactic acid) (PLA) produced by melt processing. The ageing in deionised water (DW), mechanical property changes in phosphate buffered saline (PBS) and cytocompatibility properties of these composites were investigated. In contrast to Fe10 and as a consequence of the higher surface energy and polarity of Fe5Si5, its incorporation into PLA led to increased inorganic/organic interaction indicated by a reduction in the carbonyl group of the matrix. PLA chain scission was confirmed by a greater reduction in its molecular weight in PLA-Fe5Si5 composites. In DW, the dissolution rate of PLA-Fe5Si5 was significantly higher than that of PLA-Fe10. Dissolution of the glass fibres resulted in the formation of channels within the matrix. Initial flexural strength was significantly increased through PGF incorporation. After PBS ageing, the reduction in mechanical properties was greater for PLA-Fe5Si5 compared to PLA-Fe10. MC3T3-E1 preosteoblasts seeded onto PG discs, PLA and PLA-PGF composites were evaluated for up to 7 days indicating that the materials were generally cytocompatible. In addition, cell alignment along the PGF orientation was observed showing cell preference towards PGF.     

Electron beam irradiation of low-density polyethylene filled with metal hydroxides for wire and cable applications

The effects of electron beam irradiation for crosslinking of polymers used for wire and cable insulations are still being researched. In this research, the influence of electron beam irradiation on the different blends of low-density polyethylene (LDPE) filled with aluminum trihydrate and magnesium hydroxide (ATH, MH) were studied. It was revealed by melt flow index, tensile strength, and elongation at break tests that addition of MH to LDPE increases the adhesion forces inside polymer matrices more efficient than similar ATH/LDPE compounds. Field emission scanning electron microscopy test showed that MH is platy in structure and more homogenous mixed than ATH with LDPE. The results on thermogravimetric analysis and limiting oxygen index tests revealed that the thermal stability and incombustibility properties of MH blends are more efficient than similar ATH blends. Meanwhile, it was observed by smoke density test that MH blends produce the lowest smoke density compared with virgin LDPE and similar ATH blends. It was also observed that increasing irradiation by electron beam had impressive affections on the density, gel content, and mechanical properties for all the polymeric samples in this study.     

Effect of nanoclay particles on mold‐filling performance in composites made via resin infusion process

This study investigates the effect of 3 and 5 wt% nanoclay (Cloisite 30B) addition on mold filling time and performance of continuous glass filament mat reinforced unsaturated polyester (UP) resin composites made by vacuum infusion process. X‐ray diffraction and transmission electron microscopy analysis as well as viscosity change in liquid state resin confirmed intercalation and exfoliation of the nanoclay in the resin system. The result shows mold filling time increase of 3 and 2.4 times for the samples containing 3 and 5 wt% nanoclay, respectively, compared with nanoclay‐free sample. This increase in mold filling time is directly attributed to the increase in resin viscosity. Filtration of nanoclay particles were observed in the resin flow direction. Result showed 8 and 14% filtration of nanoclay in flow direction for the samples with 3 and 5 wt% nanoclay content, respectively. Nanoclay containing specimens prepared from near resin entry port area showed relatively higher flexural and tensile modulus and as well as strength compared to specimens prepared from area close to vacuum port area. The result showed best performance for 3 wt% nanoclay containing specimen. However, impact strength decreased about 6.1 and 10.8% for 3 and 5% nanoclay, respectively. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Experimental investigation on reprocessing of extruded wood flour/HDPE composites

This article presents an experimental study on the change in the properties of wood–plastic composites (WPCs) when reprocessed. The degree of properties degradation upon reprocessing, for recycling purpose, can be considered as a key factor to choose an alternative against discarding into the environment. A material which retains its properties when recycled, or at least exhibits insignificant reduction in its properties, is favorable in environmental point of view. To investigate the reprocessing effect on the WPC properties, in this study, cylindrical profiles of WPC, with 60 wt% of wood content, were produced using a twin screw extruder, at first stage (virgin WPC). These profiles were then chopped into granules and used in the reproduction of the same shaped product (recycled WPC). For the measurement of mechanical properties, tensile and three‐point bending tests were conducted. Differential scanning calorimetry (DSC) test was performed to compare thermal behavior of the neat HDPE, virgin and recycled composites. Scanning electron microscopy (SEM) images were also produced to observe the adhesion quality of the components and changes in wood particles size. Physical properties such as density and water uptake were also measured. A reduction in strength was observed upon recycling which was accompanied with the decrease in density, while an increase in the flexural modulus was noticed. The results also indicate that the recycled samples exhibit a higher water uptake. Analysis of thermal behavior showed a slight increase in the melting temperature of the reprocessed composite and decrease in the degree of crystallinity especially at the first stage of the HDPE process. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

An investigation on effect of geometrical parameters on spray cone angle and droplet size distribution of a two-fluid atomizer

A visual study is conducted to determine the effect of geometrical parameters of a two-fluid atomizer on its spray cone angle. The liquid (water) jets exit from six peripheral inclined orifices and are introduced to a high speed gas (air) stream in the gravitational direction. Using a high speed imaging system, the spray cone angle has been determined in constant operational conditions, i.e., Reynolds and Weber numbers for different nozzle geometries. Also, the droplet sizes (Sauter mean diameter) and their distributions have been determined using Malvern Master Sizer x. The investigated geometrical parameters are the liquid jet diameter, liquid port angle and the length of the gas-liquid mixing chamber. The results show that among these parameters, the liquid jet diameter has a significant effect on spray cone angle. In addition, an empirical correlation has been obtained to predict the spray cone angle of the present two-fluid atomizer in terms of nozzle geometries.     

Calculation of total effective dose equivalent and collective dose in the event of a LOCA in Bushehr Nuclear Power Plant

In this research, total effective dose equivalent (TEDE) and collective dose (CD) are calculated for the most adverse potential accident in Bushehr Nuclear Power Plant from the viewpoint of radionuclides release to the environment. Calculations are performed using a Gaussian diffusion model and a slightly modified version of AIREM computer code to adopt for conditions in Bushehr. The results are comparable with the final safety analysis report which used DOZAM code. Results of our calculations show no excessive dose in populated regions. Maximum TEDE is determined to be in the WSW direction. CD in the area around the nuclear power plant by a distance of 30 km (138 man Sv) is far below the accepted limits. Thyroid equivalent dose is also calculated for the WSW direction (maximum 25.6 mSv) and is below the limits at various distances from the reactor stack.