Chymotrypsin from the hepatopancreas of cuttlefish (Sepia officinalis) with high activity in the hydrolysis of long chain peptide substrates: Purification and biochemical characterisation

Chymotrypsin from the hepatopancreas of cuttlefish (Sepia officinalis) was purified to homogeneity, with a 120-fold increase in specific activity and 23% recovery. The molecular weight of the purified chymotrypsin was estimated to be 28 kDa by sodium dodecyl sulphate–polyacrylamide gel electrophoresis. The optimum pH and temperature for the chymotrypsin activity were pH 8.5 and 55 °C, respectively, using succinyl-l-ala-ala-pro-l-phenylalanine-p-nitroanilide (SAAPFpNA) as a substrate. The enzyme was extremely stable in the pH range of 7.0–10.0 and highly stable up to 50 °C after 1 h incubation. This proteinase was strongly inhibited by chymostatin, soybean trypsin inhibitor, diisopropylfluorophosphate and phenylmethylsulfonyl fluoride, but was not inhibited by tosyl-l-phenylalanine chloromethyl ketone, N-carbobenzoxy-phenylalanine chloromethyl ketone or N_α-tosyl-l-lysine chloromethyl ketone. The enzyme hydrolysed long chymotrypsin peptide substrates SAAPFpNA, SAAPLpNA and ZAALpNA and did not hydrolyse short chymotrypsin substrates. Kinetic parameters of the enzymatic reaction demonstrated that the best substrate was SAAPFpNA, with k_cat 18 s^?1 and K_m 22 μM. However, the enzyme had a lower K_m for SAAPLpNA, 54 μM.The N-terminal amino acid sequence of the first 20 amino acids of the purified chymotrypsin was IVGGQEATIGEYPWQAALQV.     

Visual navigation of wheeled mobile robots using direct feedback of a geometric constraint

Many applications of wheeled mobile robots demand a good solution for the autonomous mobility problem, i.e., the navigation with large displacement. A promising approach to solve this problem is the following of a visual path extracted from a visual memory. In this paper, we propose an image-based control scheme for driving wheeled mobile robots along visual paths. Our approach is based on the feedback of information given by geometric constraints: the epipolar geometry or the trifocal tensor. The proposed control law only requires one measurement easily computed from the image data through the geometric constraint. The proposed approach has two main advantages: explicit pose parameters decomposition is not required and the rotational velocity is smooth or eventually piece-wise constant avoiding discontinuities that generally appear in previous works when the target image changes. The translational velocity is adapted as demanded for the path and the resultant motion is independent of this velocity. Furthermore, our approach is valid for all cameras with approximated central projection, including conventional, catadioptric and some fisheye cameras. Simulations and real-world experiments illustrate the validity of the proposal.     

Compatibility of Fibreglass Woven Roving and Commercially Available Phenolic Resins

Three commercially available phenolic resins are assessed for compatibility with a fibreglass wovenroving reinforcement. Compatibility assessment is based on laminate physical properties f flexuralstrength and modulus in three and four point bending, interlaminar shear strength, and tensilestrength and modulus. The physical properties are also used for assessment of hand laminatedglass/phenolic systems     

Vacuum Drying of Common Date Pulp Cubes

Drying ability of date (Phoenix dactylifera L.) pulp cubes from three Algerian common varieties (Mech-Degla, Degla-Beida, and Frezza) were investigated. Drying process was carried out under partial vacuum (200 mbar) at 60, 80, and 100°C. Compared to the Newton model, the Henderson and Pabis model better described drying kinetic of Mech-Degla and Frezza pulps at 60 and 80°C with a mean relative error (MRE) not higher than 6.07%. The same model fits experimental data at 60°C for Degla-Beida (R² = 0.988; MRE = 6.07) as well as at 100°C for only Mech-Degla (R² > 0.98, MRE = 8.61%).     

Characterization of the Tunisian phosphogypsum and its valorization in clay bricks

This study concerns the analysis of the incorporation of phosphogypsum (PG) into the fired clay bricks. In Tunisia, for several years, a set of phosphoric acid production factories have produced PG in large quantities (approximately 10 million tons per year). Currently, in Sfax (Center-East of Tunisia), the PG is stored into piles in the vicinity of the factory, by dry or wet process. The storage of PG, even though presenting a low radioactivity, causes pollution to the watertable and to the soil (due to the infiltration of acid and heavy metals). After characterization, the Tunisian PG, which plays the part of a grease-remover, was introduced into the clay bricks with different mass percentages of 0%, 5%, 15%, 25%, 30% and 40%. The study involved physical, chemical, mechanical and environmental tests on the obtained bricks.The obtained results showed that with 30% of PG incorporation, the bricks successfully satisfied the standard requirements. The increase of the percentage of PG resulted in a decrease in the mechanical strengths of these mini-bricks, but it is still higher than the standards limits. The 25% ratio of substitution appeared to be the most effective considering the performed tests.     

Defluorination of Wet-Phosphoric Acid： Equilibrium and Kinetic Studies

This study describes the advantages of using iron-oxide-pillared MF （montmorillonite） and EDTA （ethylenediaminetetraacetic acid）-pillared MD （montmorillonite） for the removal of fluoride in the phosphoric acid. The MF and MD were characterized by using BET （Brunauer-Emmett-Teller） and SEM （scanning electron microscope） for there to appreciate their textural and structural properties and in order to appraise their capacity in the fixation of the fluorine experimental results of fluorine adsorption show a defluoration of the phosphoric acid passing beyond 90% with both clays with a light performance for the MD. The kinetics of fluorine adsorption on MF and on MD has been measured at different temperatures. Indeed, the adsorbed quantity increases more favorably to temperatures more high. This kinetics could be described by two models： pseudo-first-order or pseudo-second-order, which depends on temperature and the nature of adsorbent. At different temperatures used and with various adsorbents （MD and MF, the pseudo second order model was the most reliable to determine the order of kinetics of adsorption of fluorine, which is also reflected a good correlation coefficient （above 0.99）. The fluoride sorption was reasonably explained with Langmuir or Freundlich isotherms. Thermodynamic parameters such as AG~, AH~, AS~ and kinetic one E,, （apparent activation energy） were calculated in order to understand the nature of sorption process. Results indicate that the mechanism of adsorption of the ion of fluoride on the pillared montmorillonite is an exothermic reaction. During equilibrium conditions, both the systems showed negative Gibbs energy, which indicates stability of system. The values of apparent activation energy for the both clays show that the adsorption of F ions is easier on the MF.     

Fiber single crystal growth by LHPG technique and optical characterization of Ce-doped Lu2SiO5

The laser heated pedestal growth (LHPG) technique has been applied to grow undoped and doped Lu₂SiO₅:Ce³⁺ (LSO:Ce) single crystals fibers with stable diameter. The starting cerium concentration in the melt was [0.05–1] at.%. The thermal and growth conditions allowing pulling transparent single crystals fiber’s were optimised. The fibers have been grown under N₂ + 1% O₂ atmosphere (1 bar). The Ce³⁺ segregation coefficient is 0.28 greater than the crystal grown by Czochralski technique. The as grown fibers demonstrated scintillating properties.     

A novel aspartic protease from the viscera of Sardinelle (Sardinella aurita): Purification and characterisation

A novel aspartic protease was extracted from the defatted viscera of sardinelle (Sardinella aurita) and purified, with a 9.5-fold increase in specific activity and 23.3% recovery. The molecular weight of the purified enzyme was estimated to be 17 kDa by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). The purified enzyme appeared as a single band on native-PAGE. The optimum pH and temperature for protease activity were around 3.0 and 40 °C, respectively. The enzyme showed pH stability between 2.0 and 5.0 and retained more than 50% of its activity after heating for 30 min at 50 °C. The enzyme lost 90% of its activity after incubation with pepstatin A at room temperature, but was not inhibited by soybean trypsin inhibitor or phenylmethylsulfonyl fluoride. Its K_m value was determined to be 0.73 × 10⁻⁴ M using haemoglobin as a substrate. The N-terminal 12 amino acid sequence of the purified acidic protease was R V I I E D X D Q F C T. This sequence showed low homology with aspartic peptidases of several other species of fish, suggesting that the enzyme is a new aspartic protease.     

Fault diagnosis of rotary kiln using SVM and binary ACO

This paper proposes a novel hybrid algorithm for fault diagnosis of rotary kiln based on a binary ant colony (BACO) and support vector machine (SVM). The algorithm can find a subset selection which is attained through the elimination of the features that produce noise or are strictly correlated with other already selected features. The BACO algorithm can improve classification accuracy with an appropriate feature subset and optimal parameters of SVM. The proposed algorithm is easily implemented and because of use of a simple filter in that, its computational complexity is very low. The performance of the proposed algorithm is evaluated through two real Rotary Cement kiln datasets. The results show that our algorithm outperforms existing algorithms.