Extraction and characterization of chitin and chitosan from crustacean by-products: Biological and physicochemical properties

Chitin has been extracted from two Tunisian crustacean species. The obtained chitin was transformed into the more useful soluble chitosan. These products were characterized by their biological activity as antimicrobial and antifungal properties. The tested bacterial strains were Escherichia coli American Type Cell Culture (ATCC) 25922, Pseudomonas aeruginosa ATCC 27950 and Staphylococcus aureus ATCC 25923. Four fungi strains were also tested Candida glabrata, Candida albicans, Candidaparapsilensis and Candida kreusei. Squilla chitosan showed a minimum inhibitory concentration (MIC) against the different fungi exceptionally for C. kreusei. Their antioxidant activity was investigated with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and inhibition of linoleic acid peroxidation. Parapenaeus longirostris Chitosan showed the highest radical scavenging properties. Chitin and chitosan produced were also characterized with Fourier Transform Infrared Spectroscopy (FTIR).Key words: Antibacterial, antifungal, antioxidant, chitin, chitosan, crustacean

In Vitro Bioactivity of Astaxanthin and Peptides from Hydrolisates of Shrimp (Parapenaeus longirostris) By-Products: From the Extraction Process to Biological Effect Evaluation, as Pilot Actions for the Strategy "From Waste to Profit"

Non-edible parts of crustaceans could be a rich source of valuable bioactive compounds such as the carotenoid astaxanthin and peptides, which have well-recognized beneficial effects. These compounds are widely used in nutraceuticals and pharmaceuticals, and their market is rapidly growing, suggesting the need to find alternative sources. The aim of this work was to set up a pilot-scale protocol for the reutilization of by-products of processed shrimp, in order to address the utilization of this valuable biomass for nutraceutical and pharmaceuticals application, through the extraction of astaxanthin-enriched oil and antioxidant-rich protein hydrolysates. Astaxanthin (AST) was obtained using "green extraction methods," such as using fish oil and different fatty acid ethyl esters as solvents and through supercritical fluid extraction (SFE), whereas bioactive peptides were obtained by protease hydrolysis. Both astaxanthin and bioactive peptides exhibited bioactive properties in vitro in cellular model systems, such as antioxidant and angiotensin I converting enzyme (ACE) inhibitory activities (IA). The results show higher astaxanthin yields in ethyl esters fatty acids (TFA) extraction and significant enrichment by short-path distillation (SPD) up to 114.80 ± 1.23 µg/mL. Peptide fractions of <3 kDa and 3-5 kDa exhibited greater antioxidant activity while the fraction 5-10 kDa exhibited a better ACE-IA. Lower-molecular-weight bioactive peptides and astaxanthin extracted using supercritical fluids showed protective effects against oxidative damage in 142BR and in 3T3 cell lines. These results suggest that "green" extraction methods allow us to obtain high-quality bioactive compounds from large volumes of shrimp waste for nutraceutical and pharmaceutical applications

Outcome of Quality of Life for Women Undergoing Autologous versus Alloplastic Breast Reconstruction following Mastectomy:A Systematic Review and Meta-Analysis

Background: This review aimed to meta-analyze the quality of life of alloplastic versus autologous breast reconstruction, when measured with the BREAST-Q. Methods: An electronic PubMed and EMBASE search was designed to find articles that compared alloplastic versus autologous breast reconstruction using the BREAST-Q. Studies that failed to present BREAST-Q scores and studies that did not compare alloplastic versus autologous breast reconstruction were excluded. Two authors independently extracted data from the included studies. A standardized data collection form was used. Quality was assessed using the Newcastle-Ottawa Scale. The mean difference and 95 percent confidence intervals between breast reconstruction means were estimated for each BREAST-Q subscale. Forest plots and the I2statistic were used to assess heterogeneity and funnel plot publication bias. The Z test was used to assess overall effects. Results: Two hundred eighty abstracts were found; 10 articles were included. Autologous breast reconstruction scored significantly higher in the five subscales than alloplastic breast reconstruction. The Satisfaction with Breasts subscale indicated the greatest difference, with a mean difference of 6.41 (95 percent CI, 3.58 to 9.24; I2= 70 percent). The Satisfaction with Results subscale displayed a mean difference of 5.52. The Sexual Well-Being subscale displayed a mean difference of 3.85. The Psychosocial Well-Being subscale displayed a mean difference of 2.64. The overall difference in physical well-being was significant, with high heterogeneity (mean difference, 3.33; 95 percent CI, 0.18 to 6.48; I2= 85). Conclusion: Autologous breast reconstruction had superior outcomes compared with alloplastic breast reconstruction as measured by the BREAST-Q

The Effect of Smoking and Body Mass Index on The Complication Rate of Alloplastic Breast Reconstruction

Background and Aims: The aim of this study was to evaluate the effect of smoking and body mass index on the occurrence of complications after alloplastic breast reconstruction. Materials and Methods: A consecutive series of 56 patients treated with immediate or delayed alloplastic breast reconstruction, including six cases combined with latissimus dorsi flap, at three hospitals between 2012 and 2018 were included. Complications were scored and defined according to Clavien–Dindo. To evaluate the impact of smoking, body mass index, and other potential risk factors on the occurrence of any and severe complications, univariate and multivariate logistic regression analyses were applied to estimate odds ratios and 95% confidence intervals. Results: In 56 patients, 22 patients had a complication. As much as 46% of smokers had severe complications compared to 18% of non-smokers. Of patients with body mass index ⩾ 25, 40% had severe complications compared to 10% with body mass index < 25. Smokers had eight times more chance of developing severe complications than non-smokers (ORadjusted = 8.0, p = 0.02). Patients with body mass index ⩾ 25 had almost 10 times more severe complications compared to patients with body mass index ⩽ 25 (ORadjusted = 9.9, p = 0.009). No other risk factors were significant. Conclusion: Smoking and body mass index ⩾ 25 both increased the complication rate to such an extent that patients should be informed about their increased risk for complications following alloplastic breast reconstruction and on these grounds surgeons may delay alloplastic breast reconstruction. It is an ethical dilemma whether one should deny overweight and obese patients and those who smoke an immediate alloplastic breast reconstruction. For both life style interventions, adequate guidance should be made available

Fractional-order controllers for stick-slip vibration mitigation in oil well drill-strings

Drillstring–borehole interaction can produce severely damaging vibrations. An example is stick–slip vibration, which negatively affects drilling performance, tool integrity and completion time, and costs. Attempts to mitigate stick–slip vibration typically use passive means and/or change the operation parameters, such as weight on bit and rotational speed. Automating the latter approach, by means of feedback control, holds the promise of quicker and more effective mitigation. The present work presents three separate fractional-order controllers for mitigating drillstring slip–stick vibrations. For the sake of illustration, the drillstring is represented by a torsional vibration lumped parameter model with four degrees of freedom, including parameter uncertainty. The robustness of these fractional-order controllers is compared with traditional proportional-integral-derivative controllers under variation of the weight on bit and the drill bit’s desired rotary speed. The results confirm the proposed controllers effectiveness and feasibility, with rapid time response and less overshoot than conventional proportional-integral-derivative controllers.This publication was made possible by an NPRP grant (NPRP10-0101–170081) from the Qatar National Research Fund (a member of Qatar Foundation)

The Dexi-SH* model for a multivariate assessment of agro-ecological sustainability of dairy grazing systems

Dexi-SH* is an ex ante multivariate model for assessing the sustainability of dairy cows grazing systems. This model is composed of three sub-models that evaluate the impact of the systems on: (i) biotic resources; (ii) abiotic resources, and (iii) pollution risks. The structuring of the hierarchical tree was inspired by that of the Masc model. The choice of criteria and their aggregation modalities were discussed within a multi-disciplinary group of scientists. For each cluster, a utility function was established in order to determine weighting and priority functions between criteria. The model can take local and regional conditions and standards into account by adjusting criterion categories to the agroecological context, and the specific views of the decision makers by changing the weighting of criteria

Formulation and Optimization by Experimental Design of Low-Fat Mayonnaise Based on Soy Lecithin and Whey

The main objective of this study is to develop a new formula for a diet mayonnaise-like sauce without cholesterol. Emulsifying power is provided by the use of soy lecithin and the total fat content was limited to 16%. Droplet size measurement of employed mayonnaise samples at different times show that the largest diameter of fat does not exceed 18.5 µm with a yield stress of 56.1 Pa. Results of stability to centrifugation reveal that the absence of the supernatant oily layer ensures the stability of the emulsion. Using the experimental design method, the number of trials can be limited to a number of 16 experiments, and best formulation of the mayonnaise (without cholesterol) was obtained