Alkaline Proteases Produced by Bacillus licheniformis RP1 Grown on Shrimp Wastes: Application in Chitin Extraction, Chicken Featherdegradation and as a Dehairing Agent

Anissa Haddar,Noomen Hmidet,Olfa Ghorbel-Bellaaj,Nahed Fakhfakh-Zouari,Alya Sellami-Kamoun,Moncef Nasri 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.4

The current increase in the amount of shrimp wastes produced by the shrimp industry has led to the need in finding new methods for shrimp wastes disposal. In this study, Bacillus licheniformis RP1 was shown to produce proteases when grown in media containing shrimp wastes powder as a sole carbon and nitrogen source, indicating that this bacteria could obtain its carbon and nitrogen requirements directly from shrimp wastes. The maximum protease production was obtained when the strain was grown in a medium containing (g/L): shrimp wastes powder 30, KCl 1.5, K_2HPO_4 0.5, and KH_2PO_4 0.5. Using casein zymography, the crude protease preparation was found to produce at least seven proteases. The proteases of B. licheniformis RP1 were tested for shrimp waste deproteinization in the preparation of chitin. The percent of protein removal after 3 h hydrolysis at 60°C and at an enzyme/substrate (E/S) ratio of 0.5 and 5 (Unit of enzyme/mg of protein) were about 68 and 81%, respectively. Additionally,B. licheniformis RP1 showed important feather degrading activity. Complete solubilisation of whole feathers was observed after 24 h of incubation at 50°C. More interestingly, the RP1 proteolytic preparation demonstrated powerful dehairing capabilities for hair removal from skin. Collagen, which is the major leather-forming protein, was not significantly degraded. Considering its promising properties, B. licheniformis RP1 enzymatic preparation may be considered a potential candidate for future use in several biotechnological processes.

Upgrading of UV Protection Properties of Several Textile Fabrics by Their Dyeing with Grape Pomace Colorants

Noureddine Baaka,Manel Ben Ticha,Wafa Haddar,Maria Teresa Pessoa Amorim,Mohamed Farouk Mhenni 한국섬유공학회 2018 Fibers and polymers Vol.19 No.2

The desire to offer clothes protective properties against the harmful UV rays continues to attract the interest of researchers. Several works have been elaborated in this topic and have proved that the clothes do not protect sufficiently against the solar ultraviolet radiation. Their protectiveness depends on the fiber type, the fabric composition, the fabric construction and the dyeing method. This research presents a novel approach which target the improvement of the textile protective properties against UV rays by their dyeing with grape pomace aqueous extract. These properties were tested in combination with several fabrics (natural and synthetic) and mordants (potassium alum and ferrous sulphate). Through this study, it has been shown that the UV-protective properties of the several dyed fibers were upgraded after dyeing with the grape pomace extract, and is intensely relying on the types of fibers and mordants.

Effective vibration control of multimodal structures with low power requirement

Thamina Loukil,Mohamed Ichchou,Olivier Bareille,Mohamed Haddar 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.13 No.3

In this paper, we investigate the vibration control of multimodal structures and present anefficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of theoptimal law such that the controller follows this latter only if there is sufficient energy which will beextracted directly from the system vibrations itself. The control algorithm is presented and validated for acantilever beam structure subjected to external perturbations. Comparisons between the proposed lawperformances and those obtained by independent modal space control (IMSC) and semi-active controlschemes are offered.

Effective vibration control of multimodal structures with low power requirement

Loukil, Thamina,Ichchou, Mohamed,Bareille, Olivier,Haddar, Mohamed Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.3

In this paper, we investigate the vibration control of multimodal structures and present an efficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of the optimal law such that the controller follows this latter only if there is sufficient energy which will be extracted directly from the system vibrations itself. The control algorithm is presented and validated for a cantilever beam structure subjected to external perturbations. Comparisons between the proposed law performances and those obtained by independent modal space control (IMSC) and semi-active control schemes are offered.

A polynomial chaos method to the analysis of the dynamic behavior of spur gear system

Guerine, A.,El Hami, A.,Fakhfakh, T.,Haddar, M. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.4

In this paper, we propose a new method for taking into account uncertainties based on the projection on polynomial chaos. The new approach is used to determine the dynamic response of a spur gear system with uncertainty associated to gear system parameters and this uncertainty must be considered in the analysis of the dynamic behavior of this system. The simulation results are obtained by the polynomial chaos approach for dynamic analysis under uncertainty. The proposed method is an efficient probabilistic tool for uncertainty propagation. It was found to be an interesting alternative to the parametric studies. The polynomial chaos results are compared with Monte Carlo simulations.

Modeling and computation of the three-roller bending process of steel sheets

Ahmed Ktari,Zied Antar,Nader Haddar,Khaled Elleuch 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.1

Sheet metal bending processes are some of the most commonly used industrial manufacturing operations. The development and optimization of these processes are time consuming and costly. Therefore, finite element simulations may aid the design and quality assurance of sheet metal products. In the present study, a commercial finite element package was used to analyze the three-roller bending of a steel sheet. A two-dimensional finite element model of this process was built under the ABAQUS/Explicit environment based on the solution of several key techniques, such as contact boundary condition treatment, material property definition, meshing technique, and so on. Maps with desired curvature radii were established by varying the distance between the two bottom rollers and the position of the upper one. The developed maps made the rolling process easier and less time consuming. An industrial experiment using optimized numerical results was carried out to validate the numerical model. Residual stress and equivalent plastic strain distributions were also studied. The numerical spring back phenomenon was compared with analytical results.

Protein Hydrolysates from Bluefin Tuna (Thunnus thynnus) Heads as Influenced by the Extent of Enzymatic Hydrolysis

Ali Bougatef,Rafik Balti,Anissa Haddar,Kemel Jellouli,Nabil Souissi,Moncef Nasri 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

Functional properties and antioxidant activities of protein hydrolysates from tuna (Thunnus thynnus) heads (THPHs), with different degrees of hydrolysis, obtained by treatment with Bacillus mojavensis A21 alkaline proteases and Alcalase, were investigated. Protein content of all freeze-dried THPHs ranged from 73.74 ± 0.5 to 78.56 ±1.2%. The THPHs had excellent solubility, compared to untreated tuna head proteins and possessed interfacial properties, which were governed by their concentrations. Similarly, at a degree of hydrolysis (DH) of 12 and 15%,> 90% nitrogen solubility was observed at all experimental pH values tested. The emulsifying activity index (EAI) and emulsion stability index (ESI) of both hydrolysates at different DHs decreased (p < 0.05) with increasing DH. At low DH (5%), hydrolysates exhibited strong emulsifying properties. All THPHs produced by the A21 proteases generally showed higher antioxidative activity than that of the Alcalase protein hydrolysates. The highest DPPH radical-scavenging activity (78 ± 2.1% at 3 mg/mL) was obtained with a DH of 15%. The IC50 value for the β-carotene bleaching assay was 0.5 ± 0.03 mg/mL. Alcalase (DH = 12%) and A21 (DH = 15%) protein hydrolysates contained glutamic acid/glutamine and arginine as the major amino acids, followed by lysine, aspartic acid/asparagine, histidine, valine, phenylalanine, and leucine. In addition, the THPHs had a high percentage of essential amino acids, which made up 50.52 and 50.47%, of the protein hydrolysates obtained by the Alcalase and A21proteases, respectively. Therefore, THPHs can be used as a promising source of functional peptides with antioxidant properties. Functional properties and antioxidant activities of protein hydrolysates from tuna (Thunnus thynnus) heads (THPHs), with different degrees of hydrolysis, obtained by treatment with Bacillus mojavensis A21 alkaline proteases and Alcalase, were investigated. Protein content of all freeze-dried THPHs ranged from 73.74 ± 0.5 to 78.56 ±1.2%. The THPHs had excellent solubility, compared to untreated tuna head proteins and possessed interfacial properties, which were governed by their concentrations. Similarly, at a degree of hydrolysis (DH) of 12 and 15%,> 90% nitrogen solubility was observed at all experimental pH values tested. The emulsifying activity index (EAI) and emulsion stability index (ESI) of both hydrolysates at different DHs decreased (p < 0.05) with increasing DH. At low DH (5%), hydrolysates exhibited strong emulsifying properties. All THPHs produced by the A21 proteases generally showed higher antioxidative activity than that of the Alcalase protein hydrolysates. The highest DPPH radical-scavenging activity (78 ± 2.1% at 3 mg/mL) was obtained with a DH of 15%. The IC50 value for the β-carotene bleaching assay was 0.5 ± 0.03 mg/mL. Alcalase (DH = 12%) and A21 (DH = 15%) protein hydrolysates contained glutamic acid/glutamine and arginine as the major amino acids, followed by lysine, aspartic acid/asparagine, histidine, valine, phenylalanine, and leucine. In addition, the THPHs had a high percentage of essential amino acids, which made up 50.52 and 50.47%, of the protein hydrolysates obtained by the Alcalase and A21proteases, respectively. Therefore, THPHs can be used as a promising source of functional peptides with antioxidant properties.

A polynomial chaos method to the analysis of the dynamic behavior of spur gear system

A. Guerine,A. El Hami,T. Fakhfakh,M. Haddar 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.4

In this paper, we propose a new method for taking into account uncertainties based on the projection on polynomial chaos. The new approach is used to determine the dynamic response of a spur gear system with uncertainty associated to gear system parameters and this uncertainty must be considered in the analysis of the dynamic behavior of this system. The simulation results are obtained by the polynomial chaos approach for dynamic analysis under uncertainty. The proposed method is an efficient probabilistic tool for uncertainty propagation. It was found to be an interesting alternative to the parametric studies. The polynomial chaos results are compared with Monte Carlo simulations.

Simplified model to study the dynamic behaviour of a bolted joint and its self loosening

Olfa Ksentini,Bertrand Combes,Mohamed Slim Abbes,Alain Daidié,Mohamed Haddar 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3

Bolted joints are essential elements of mechanical structures and metal constructions. Although their static behaviour is fairly well known, their dynamic behaviour due to shocks and vibrations has been less studied, because of the large size of the finite element models needed for a detailed simulation. This work presents four different simplified models suitable for studying the dynamic behaviour of an elementary bolted joint. Three of them include contact elements to allow sliding of the screw head and the nut on the assembled parts, and the last one allows rotation between screw and nut. A penalty approach based on the Coulomb friction model is used to model contact. The results show that these models effectively represent the dynamic behaviour, with different accuracy depending on the model details. The last model simulates the self loosening of a bolt subjected to transversal vibrations.

Dynamic behavior of the one-stage gear system with uncertainties

M. Beyaoui,A. Guerine,L. Walha,A. El Hami,T. Fakhfakh,M. Haddar 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.3

In this paper, we propose a method for taking into account uncertainties based on the projection on polynomial chaos. Due to the manufacturing and assembly errors, uncertainties in material and geometric properties, the system parameters including assembly defect, damping coefficients, bending stiffness and traction-compression stiffness are uncertain. The proposed method is used to determine the dynamic response of a one-stage spur gear system with uncertainty associated to gear system parameters. An analysis of the effect of these parameters on the one stage gear system dynamic behavior is then treated. The simulation results are obtained by the polynomial chaos method for dynamic analysis under uncertainty. The proposed method is an efficient probabilistic tool for uncertainty propagation. The polynomial chaos results are compared with Monte Carlo simulations.