Comparative numerical and experimental investigation of static and dynamic characteristics of composite plates

Marija Baltić,Jelena Svorcan,Bojan Perić,Miloš Vorkapić,Toni Ivanov,Ognjen Peković 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

In order to investigate both static and dynamic characteristics of composite plates and validate a contemporary, non-invasive experimental technique a comparative experimental and numerical analysis was performed. Three, geometrically the same but different in ply orientation, carbon-epoxy laminates were tested in both healthy and damaged conditions. Damages were inflicted in a shape of horizontal crack. Experiments and numerical simulations were performed by digital image correlation (DIC) and finite element method (FEM), respectively. Obtained time-responses of the tested structures were fast Fourier transformed (FFT) to frequency domain for a clearer understanding of natural frequencies and oscillation modes. Results are presented in tabular and graphical form. The overall correspondence of two sets of structural displacements is satisfactory. Some discrepancies might be contributed to the idealized geometry and restraint consideration. Also, due to the fast damping of higher tones, the errors in determining higher natural frequencies increase but still remain in 5 % range.

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.

Gestational Exposure to Pesticides Induces Oxidative Stress and Lipid Peroxidation in Offspring that Persist at Adult Age in an Animal Model

Ndonwi, Elvis Ngwa,Atogho-Tiedeu, Barbara,Lontchi-Yimagou, Eric,Shinkafi, Tijjani S.,Nanfa, Dieudonne,Balti, Eric V.,Indusmita, Routray,Mahmood, Amena,Katte, Jean-Claude,Mbanya, Armand,Matsha, Tandi,M Korean Society of ToxicologyKorea Environmental Mu 2019 Toxicological Research Vol.35 No.3

Pesticide exposure may induce biochemical alterations including oxidative stress and lipid peroxidation. However, in the context of developmental origin of health and disease, putative trans-generational effect of exposure to pesticides are insufficiently studied. We therefore aimed to evaluate the biochemical effect of gestational exposure to four pesticides on female Wistar rats and their offspring at adult age. We studied 30 female nulliparous Wistar rats divided into 5 equal groups. Group 1 served as the control group and received distilled water while group 2, 3, 4 and 5 received orally pesticide 1 (imidacloprid), pesticide 2 (chlorpyrifos), pesticide 3 (imidacloprid + lambda cyhalothrin) and pesticide 4 (oxamyl) respectively once daily throughout gestation at a dose equivalent to 1/10 lethal dose 50. The mothers were followed up until one month post gestation. The offspring were followed up from birth until adult age (12 weeks). In all animals at each time point we evaluated malondialdehyde (MDA), oxidative stress and liver function enzymes. There was similar variation of total body weight in all the groups during and after gestation. However, Female Wistar rats of the exposed groups had significant alterations in liver SOD (-30.8% to +64.1%), catalase (-38.8% to -85.7%) and GSH (-29.2% to -86.5%) and; kidney catalase (> 100%), GSH (> 100%). Moreover, MDA, alanine transaminase (ALT) and aspartate transaminase (AST) levels were significantly higher in pesticide exposed rats compared to the control group. Similar alterations in antioxidant enzymes, MDA and liver function enzymes were observed in offspring of treated rats evidenced at weaning and persisting until adult age. Exposure to pesticides causes oxidative stress and lipid peroxidation in exposed female Wistar rats and their offspring. The persistence in offspring at adult age suggests transgenerational adverse effects.

Gestational Exposure to Pesticides Induces Oxidative Stress and Lipid Peroxidation in Offspring that Persist at Adult Age in an Animal Model

Elvis Ngwa Ndonwi,Barbara Atogho-Tiedeu,Eric Lontchi-Yimagou,Tijjani S. Shinkafi,Dieudonne Nanfa,Eric V. Balti,Routray Indusmita,Amena Mahmood,Jean-Claude Katte,Armand Mbanya,Tandi Matsha,Jean Claude 한국독성학회 2019 Toxicological Research Vol.35 No.3

Pesticide exposure may induce biochemical alterations including oxidative stress and lipid peroxidation. However, in the context of developmental origin of health and disease, putative trans-generational effect of exposure to pesticides are insufficiently studied. We therefore aimed to evaluate the biochemical effect of gestational exposure to four pesticides on female Wistar rats and their offspring at adult age. We studied 30 female nulliparous Wistar rats divided into 5 equal groups. Group 1 served as the control group and received distilled water while group 2, 3, 4 and 5 received orally pesticide 1 (imidacloprid), pesticide 2 (chlorpyrifos), pesticide 3 (imidacloprid + lambda cyhalothrin) and pesticide 4 (oxamyl) respectively once daily throughout gestation at a dose equivalent to 1/10 lethal dose 50. The mothers were followed up until one month post gestation. The offspring were followed up from birth until adult age (12 weeks). In all animals at each time point we evaluated malondialdehyde (MDA), oxidative stress and liver function enzymes. There was similar variation of total body weight in all the groups during and after gestation. However, Female Wistar rats of the exposed groups had significant alterations in liver SOD (−30.8% to +64.1%), catalase (−38.8% to −85.7%) and GSH (−29.2% to −86.5%) and; kidney catalase (> 100%), GSH (> 100%). Moreover, MDA, alanine transaminase (ALT) and aspartate transaminase (AST) levels were significantly higher in pesticide exposed rats compared to the control group. Similar alterations in antioxidant enzymes, MDA and liver function enzymes were observed in offspring of treated rats evidenced at weaning and persisting until adult age. Exposure to pesticides causes oxidative stress and lipid peroxidation in exposed female Wistar rats and their offspring. The persistence in offspring at adult age suggests transgenerational adverse effects.

Metabolic effects of exposure to pesticides during gestation in female Wistar rats and their offspring: a risk factor for diabetes?

Ndonwi Elvis Ngwa,Atogho-Tiedeu Barbara,Lontchi-Yimagou Eric,Shinkafi Tijjani S.,Nanfa Dieudonne,Balti Eric V.,Katte Jean Claude,Mbanya Armand,Matsha Tandi,Mbanya Jean Claude,Shakir Ali,Sobngwi Eugene 한국독성학회 2020 Toxicological Research Vol.36 No.3

Some pesticides increase the risk of type 2 diabetes, but whether fetal exposure carries transgenerational risk remains unknown. We evaluated the metabolic effects of gestational exposure to chlorpyrifos and imidacloprid in female Wistar rats and their offspring. We studied female nulliparous Wistar rats, including six exposed to imidacloprid (IMI) and six to chlorpyrifos (CPF) once daily throughout gestation at 1/10 lethal dose 50, while six (control group) received distilled water. These were explored 1 month after the birth of the offspring, while their offspring were explored at weaning (4 weeks) and adult age (12 weeks). Blood glucose, insulin and lipid profile were determined at each stage, while glucose transporter 4 (GLUT4) and nuclear factor kappa beta (NFkβ) protein expression was measured in skeletal muscle at the end of follow up. Exposure to pesticides was associated with significantly higher fasting glucose (+25.4 to 30.9%) and insulin (> 100%) levels, with > 100% increased insulin resistance (HOMA-IR), − 18.3 to − 21.1% reduced HDL-cholesterol and + 60.9 to + 102.6% increased LDL-cholesterol in mothers. GLUT4 expression was reduced by 28.9–42.3% while NFkβ expression increased by 32.8–35.4% in mothers. In offspring, similar abnormalities were observed at weaning (+ 18.4 to 67.4% fasting glucose, + 57.1 to 72.2% LDL-cholesterol, + 72.3 to 78.2% fasting insulin), persisting at adult age with decreased expression of GLUT4 (− 52.8 to 54.5%) and increased expression of NFkβ (+ 30.5 to 30.7%). Gestational exposure to imidacloprid and chlorpyrifos induces hyperglycemia, insulin resistance and dyslipidemia in female Wistar rats and their offspring. The effects on offspring persist until adult age, suggesting intergenerational adverse effects.