An efficient one-pot synthesis of tetrahydrothiazolo[3,2-a]quinolin-6-one derivatives

The cysteamine hydrochloride as a practical precursor of 2-(nitromethylene)thiazolidine in the one-pot synthesis of thiazoloquinoline derivatives from aromatic aldehydes and dimedone is described. This protocol involved Michael reaction, imine–enamine tautomerization, and cyclization sequence. Simple operation under mild conditions, easy accessibility of reactants, short reaction times, simple workup procedure, high atom economy, and the use of ethanol/water as a green medium make this approach attractive for the synthesis of variety of such derivatives.     

Effect of Fe Substitution on the Structural,Magnetic and Magnetocaloric Properties of Pr0.6La0.1Mg0.3Mn1−x Fe x O3 (0≤x≤0.3) Perovskite Manganites Prepared by Sol Gel Method

Studies of the structural, magnetic, and magnetocaloric properties of polycrystalline Pr_0.6La_0.1Mg_0.3Mn_1?x Fe _x O₃ (0≤x≤0.3) perovskite manganites were carried out. The compounds were synthesized using the sol–gel method. X-Ray diffraction (XRD) analysis using Rietveld refinement shows that all our compounds crystallize in the orthorhombic structure with the Pnma space group. The surface morphology and elemental analysis of both samples were carried out by scanning electron microscopy (SEM) and the energy dispersive X-ray technique (EDX), respectively. Magnetization measurements versus temperature under magnetic applied field of 0.05 T showed that all our investigated samples display a ferromagnetic-paramagnetic transition. The substitution of Mn by Fe leads to an increase of the Curie temperature T _C from 64 K for x=0 to 380 K for x=0.3. The Arrott plots show that the phase transition is of second order. A large magnetic entropy change |ΔS _M | deduced from isothermal magnetization curves has been recorded in the parent compound Pr_0.6La_0.1Mg_0.3MnO₃ reaching a maximum of 0.79 J/kg K under a magnetic applied field of 2 T close to T _C . Our results on magnetocaloric properties suggest that the Pr_0.6La_0.1Mg_0.3MnO₃ compound is attractive as a possible refrigerant for low temperature magnetic refrigeration.     

Analysis of self-assembled monolayers on gold surfaces using direct analysis in real time mass spectrometry

Mass spectrometry was performed on self-assembled monolayers (SAMs) of dodecanethiol on gold using the new direct analysis in real time (DART) ionization technique. Observed peaks for the SAMs included monomers, dimers, and trimers of the SAM molecules, with the dimer and trimer relative peak heights enhanced as compared to the spectra for neat dodecanethiol. The possibility that the observed peaks were due to residual (noncovalently bonded) material on the surface was tested by attempting to observe residual dodecanol. No peaks corresponding to dodecanol were observed. These results indicate that DART is an excellent ionization method for the direct and unambiguous mass analysis of chemical species in self-assembled monolayers.     

Non-linear dynamic analysis of a wind turbine blade

ABSTRACT

Wind turbine blades’ dynamic behavior must be well investigated during the design process in order to avoid resonance. Modal analysis and nonlinear dynamic analysis of a rotating wind turbine blade are presented in this paper to study the effects of rotation speed on the natural frequencies and displacements. Accordingly, an enhanced finite element formulation based on uncoupled translational and rotational displacements’ kinetic energy was developed. A twisted wind turbine blade was discretized using beam elements with different cross sections; each has six degrees of freedom per node. At rest, the model results were validated using ABAQUS software. Furthermore, the effects of geometrically non-linear phenomena produced by blade displacement on the vibration characteristics of the rotating blade have been discussed. The blade non-linear problem was solved by applying the Newmark method combined with the Newton-Raphson schema. Results show that the blade natural frequencies and displacements increase under angular rotation speed augmentation. This work highlights the significant sensitivity of the blade vibration characteristics to the geometric non-linearity. Accordingly, a modal and a linear analysis are insufficient to precisely estimate the dynamic behavior of a rotating turbine blade.     

A Fast Adaptive Salt and Pepper Noise Reduction Method in Images

In this paper, an effective filtering method is proposed to remove impulse noise from images. In this two-stage method, detected noise-free pixels remain unchanged. Afterwards, a Gaussian filter with adaptive variances according to the image noise level is applied on the noisy pixels. Experimental results show that the proposed method outperforms recent impulse denoising methods in terms of PSNR, MAE, IEF, and SSIM. Moreover, the speed of the method is comparable with them, and it can be used effectively in real-time applications.     

Salt effect on phenolics and antioxidant activities of Tunisian and Canadian sweet marjoram (Origanum majorana L.) shoots

BACKGROUND: Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint. RESULTS: The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed‐phase high‐performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans‐2‐hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L^?1 NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin‐3‐galactoside and quercetin‐3‐rhamnoside. CONCLUSION: Our results confirmed the tolerance of Tunisian O. majorana plants. Copyright © 2012 Society of Chemical Industry     

Anticoagulant activities of goby muscle protein hydrolysates

The anticoagulant activities of protein hydrolysates prepared from goby muscle by treatment with various bacterial alkaline proteases were investigated. All proteases exhibited varying degrees of hydrolysis (DH) and all goby protein hydrolysates (GPHs) caused a significant prolongation of both the thrombin time (TT) and the activated partial thromboplastin time (APTT). The hydrolysate generated by the crude protease from Bacillus licheniformis NH1 displayed the highest anticoagulant activity, and the higher TT (about 32 s) at a concentration of 5 mg/mL was obtained with hydrolysate having a DH of 8.86%. This hydrolysate was then fractionated by size exclusion chromatography on a Sephadex G-25 column into five major fractions (F1–F5). Fraction F2, which exhibited the highest anticoagulant activity, was then fractionated by reversed-phase high-performance liquid chromatography. The molecular masses and amino acid sequences of four peptides in peptide sub-fraction F2–6, which exhibited the highest anticoagulant activity, were determined using ESI-MS and ESI-MS/MS, respectively. The structures of these peptides were identified as Leu-Cys-Arg, His-Cys-Phe, Cys-Leu-Cys-Arg and Leu-Cys-Arg-Arg.     

Efficacy of Sardinelle Protein Hydrolysate to Alleviate Ethanol-Induced Oxidative Stress in the Heart of Adult Rats

The present study was undertaken to examine the protective effects of sardinelle proteins hydrolysate (SPH) obtained from heads and viscera against ethanol toxicity in the heart of adult rats. Twenty-four male rats of Wistar strain, weighing at the beginning of the experiment 250 to 300 g, were used in this study. They were divided into 4 groups: group (C) served as controls, group (Eth) received 30% ethanol solution at 3 g/kg body weight, group (SPH) received only 7.27 mg of SPH/kg body weight, and group (Eth-SPH) received ethanol and sardinelle proteins hydrolysate simultaneously. All treatments were made by gavage during 15 d. Treatment with ethanol revealed a significant elevation of malondialdehyde and protein carbonyl levels in the heart and of aspartate transaminase and alanine transaminase activities in plasma. Nitric oxide levels and the activities of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase decreased. Nonenzymatic antioxidant such as reduced glutathione did not significantly change and ascorbic acid was decreased. SPH intake concomitantly with ethanol restored these parameters to near control values. These modifications confirmed histopathological aspects of the heart. The results revealed that SPH could provide protection of the myocardium against ethanol-induced oxidative damages in rats. This may be due to the high antioxidant potential of SPH.     

Improvement of functional properties and antioxidant activities of cuttlefish (Sepia officinalis) muscle proteins hydrolyzed by Bacillus mojavensis A21 proteases

Functional properties and antioxidant activities of cuttlefish (Sepia officinalis) muscle protein hydrolysates, with different degrees of hydrolysis (DH from 7.3% to 18.8%), obtained by treatment with Bacillus mojavensis A21 alkaline proteases were investigated. Protein contents for all freeze-dried cuttlefish muscle protein hydrolysates (CMPHs) ranged from 80% to 86%. For the functional properties, hydrolysis by A21 proteases increased (p < 0.05) protein solubility to above 78% over a wide pH range (2.0–11.0). However, the interfacial activities (emulsion activity index, emulsion stability index, foaming capacity and foaming stability) decreased with the increase of the DH. All CMPHs exhibited significant metal chelating activity and DPPH free radical-scavenging activity, and inhibited linoleic acid peroxidation. Antioxidant properties of protein hydrolysates increased with protein hydrolysis and the highest activities were obtained at DH of 16%. The IC₅₀ values for DPPH radical-scavenging and metal chelating activities were found to be 0.52 ± 0.01 mg/ml and 0.67 ± 0.13 mg/ml. The obtained results suggested that functional properties and antioxidant activities of cuttlefish muscle protein hydrolysates were influenced by the degree of hydrolysis.The composition of amino acids of undigested and hydrolyzed proteins was determined. CMPHs have a high percentage of essential amino acids such as arginine, lysine, histidine and leucine. They have a high nutritional value and could be used as supplement to poorly balanced dietary proteins.