Synthesis and characterization of oil sorbers based on docosanyl acrylate and methacrylates copolymers

Docosanyl acrylate (DCA) monomer was copolymerized with different monomer feed ratios of cinnamoyloxy ethyl methacrylate (CEMA) or methyl methacrylate (MMA) monomer to produce different compositions for DCA/CEMA or DCA/MMA copolymer with low conversions.¹H NMR spectroscopy was used to confirm the copolymer structure. DCA was crosslinked with different mol % of CEMA or MMA using dibenzoyl peroxide as initiator and various weight percentages of either 1,1,1‐trimethylolpropane triacrylates or 1,1,1‐trimethylolpropane trimethacrylates crosslinkers. The effects of monomer feed composition, crosslinker concentration, and the hydrophobicity of the copolymer units on swelling properties of the crosslinked polymers were studied through the oil absorbency tests. The network parameters, such as polymer solvent interaction (χ), effective crosslink density (υ_e), equilibrium modulus of elasticity (G_T), and average molecular weight between crosslinks (M_c), were determined and correlated with the structure of the synthesized copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A Novel Oil Well Cementing Technology Using Natural Fibers

In many industrial processes, the pipeline systems are lined with a protective layer of cement mortar. In petroleum wells, cement slurry is placed in a wellbore to be hardened into an impermeable mass that seals the annulus from fluid flow and protects the casing from corrosion for the life of the well. When uniform linings of neat cement fail in tension, one or more large cracks are formed and the pressurizing fluid or mud easily flows through the cracks. The necessity to check the damaging effect of plastic shrinkage in cement mortar, and thus the formation of cracks, has called for further studies in this topic. In the past, the most common research topic has been in the areas of polymer fibers that are expensive and environmentally unacceptable. In the quest of pursuing technologies that are environmentally friendly, inexpensive, and innovative, this paper suggests the use of human hair, a waste material, in order to replace polymer fibers. Hair waste has been used as a new natural fiber to reinforce mortar and cement and improve their impermeability. The investigation reported herein concerns the effects of human hair fibers on the reduction of shrinkage cracking of mortar. The influence of mix proportions on the plastic shrinkage of human hair fiber reinforced mortar has been studied. The approach selected in this study is based on the factorial design of experiments, in which the considered parameters are cement/sand ratio, water/cement ratio, and human hair fibers content. The results show that human hair fibers are effective in reducing the plastic shrinkage cracks area of mortar by a remarkable percentage up to 92%.     

The combined effects of load, moisture and temperature on the properties of E-glass/epoxy composites

The properties of an E-glass/epoxy composite were examined before and after mechanical loading and moisture conditioning. Preliminary results indicate that the modulus, strength, and strain of the E-glass/epoxy composite material are affected by the presence of moisture and mechanical loading when compared to control specimens. At shorter durations of conditioning at room temperature, a slight increase in strength and a slight decrease in modulus were observed; and at longer durations, 3000 h, a noticeable reduction in strength and strain-to-failure was observed. Specimens conditioned under stress, in water at 65 °C for 1000 h exhibited higher loss in modulus. It is speculated that constant stress may have a positive effect in short-term, and that extended exposure to moisture at room temperature leads to brittle failure while exposure at high temperatures may lead to ductile failure of E-glass/epoxy composites.     

Oxovanadium(IV) Schiff base complexes derived from 2,2′-dimethylpropandiamine: A homogeneous catalyst for cyclooctene and styrene oxidation

Tetradentate Schiff base ligands, derived from aromatic aldehydes and aliphatic diamine (2,2′-dimethylpropandiamine), and their vanadyl complexes have been prepared and characterized. Catalytic potential of these complexes was tested for the oxidation of cyclooctene and styrene using tert-butylhydroperoxide (TBHP) as oxidant. The effects of molar ratio of oxidant to substrate, temperature and solvent have been studied. Excellent selectivity of epoxidation for cyclooctene and good selectivity for styrene were obtained. The mechanism of oxidation has also been discussed.     

Simplified model of the turbine runner blade

Francis turbine blade is modelled by circular beams loaded by uniformly distributed pressure. This simplification allows for analytical calculations of maximum stresses followed by comparisons with FEM analysis for the same turbine. Two beam models have been proposed and one of them showed good correlation with FEM for different operation conditions. This model has been applied to analyse the operation data recorded during the whole time of operation of the Unit 2 of Derbendikan hydropower station. The results show evolution of the maximum tensile stresses, which makes clear that the appearance of cracks in turbine blades cannot be explained by the high stresses level alone but by combination of different factors.     

A molecular survey on virulence associated genotypes of non-O1 non-O139 Vibrio cholerae in aquatic environment of Tehran, Iran

Thirty-seven Vibrio cholerae strains were isolated from surface water sources at 5 different locations in Tehran, Iran during 2006 and were identified as non-O1 and non-O139 isolates. PCR for SXT element and class 1 integron was positive for 19% and 5.4% of isolates, respectively. PCR for virulence associated-genes within the vibrio pathogenicity island (VPI) gene cluster showed the presence of LJ, int and RJ in 8, 59 and 30% of the isolates, respectively. None of the V. cholerae isolates contained the toxin encoding genes (ace, zot, ctx) in the CTX genetic element. Biochemical fingerprinting using PhPlate system (PhP-RV) was able to type all strains and resulted in 8 common types (containing 78% of the isolates) and 8 single types (22%). Out of 37 isolates, only 26 isolates were typeable with pulsed-field gel electrophoresis (PFGE) producing banding patterns. The results presented in this study showed no genotyping correlation between the V. cholerae isolated from surface water and the clinical setting which had been reported previously by this laboratory. Furthermore, combination of PFGE and PhP-RV methods was proved beneficial for non-typeable V. cholerae isolates.     

Two methods for semi-automated quantification of changes in ventricular volume and their use in schizophrenia

Two semi-automated methods for quantification of ventricular volume change from baseline and follow-up magnetic resonance imaging scans have been developed. Technique 1 employs direct segmentation of the ventricles from both the scans using thresholding and contour extraction. Technique 2 operates on difference images produced by voxel based intensity subtraction of the baseline from the registered follow-up images. Here, all voxels with intensities above a noise threshold and in a restricted area are monitored to compute volumetric changes. In phantom measurements the first technique was accurate to 0.0046%, the second to 0.167% of the phantom volume. Results from normal volunteers was that the average ventricular volume changed by 1.52% and 1.54% for images acquired within 9 months using techniques 1 and 2, respectively. With schizophrenic patients mean change of 10.78% and 9.43% were found employing the first and second procedures, respectively. All measurements agreed with a radiologist's visual grading of the changes. Robust, objective, fast, easy-to-use, and fairly accurate procedures have been developed and validated to quantify volumetric changes.     

Dual effects of nimesulide, a COX-2 inhibitor, in human platelets

Nimesulide (CAS 51803-78-2) has been shown to exert marked anti-inflammatory effect in several in vivo models of inflammation. Since nimesulide is considered to be a selective inhibitor of COX-2, it has not been studied in detail in relation to its mechanistic effects on platelets, which express COX-1. This study was conducted to investigate the effects of nimesulide in platelet aggregation. We show that nimesulide (1-100 microM) inhibited platelet aggregation induced by adrenaline (20-200 microM). It also inhibited thromboxane A2 (TXA2) formation by platelets at low concentration (IC50; 1 microM). However, much lower concentrations of nimesulide (0.01-0.1 microM) potentiated the aggregatory response of subthreshold concentrations of adrenaline (0.2-2 microM). Such an effect was blocked by Ca2+-channel blockers, verapamil and diltiazem (IC50: 7 and 46 microM, respectively), nitric oxide donor, SNAP (IC50; 2 microM) and cinchonine (10 nM) but not by genistein (up to 10 microM). These results are indicative of the concentration-dependent dual effects of nimesulide on human platelet aggregation. The synergistic effect of low doses of nimesulide and adrenaline seems to be mediated through inhibition of multiple signalling pathways.     

Zona pellucida microdrilling with a 1.48 μm diode laser

The zona pellucida is the thick glycoprotein layer that surrounds and protects the female gamete. This layer plays an important part in mammalian reproduction. Here, the authors analyze a drilling process utilizing a 1.48 μm diode laser, and they review their mathematical model of the deposition of laser energy. They also present their results from experiments in which they drilled mouse zona pellucida. It is demonstrated that varying laser power or exposure duration controls the size of the hole. The authors observe that hole diameter is very sensitive to changes in exposure duration at the highest power used, due to a substantial increase in laser heating efficiency. At lower power settings, heat diffusion prevents efficient heating. Thus, deposition of the same amount of energy deposition results in a reduced hole size