220 research outputs found
From seaweeds to hydrogels: Recent progress in kappa-2 carrageenans
Hybrid carrageenans, also called kappa-2 (K2) or weak kappa, are a class of sulfated polysaccharides with thermo-reversible gelling properties in water and are extracted from a specific family of red seaweeds. K2 are known in the industry for their texturizing properties which are intermediate between those of kappa-carrageenans (K) and iota-carrageenans (I). As such, K2 are gaining industrial interest, as they can replace blends of K and I (K + I) in some niche applications. Over the last decade or so, some progress has been made in unravelling K2's chemical structure. The understanding of K2 gel's structure-rheological properties' relationships has also improved. Such recent progress is reported here, reviewing the literature on gelling K2 published since the last review on the topic. The focus is on the seaweeds used for extracting K2, their block copolymer chemical structures, and how these impact on the gel's formation and rheological properties. The outcome of this review is that additional rheological and structural studies of K2 hydrogels are needed, in particular to understand their viscoelastic behavior under large deformation and to unravel the differences between the texturizing properties of K2 and K + I.This work was supported by the Fundação para a Ciência e Tecnologia (FCT), through the E2B2-PHACAR project, grant number: PTDC/BII-BIO/5626/2020. Additional financial support by the FCT under the framework of Strategic Funding grant: UID/CTM/50025/2020 and grant: CEECINST/00156/2018 are also acknowledged
Colistin Resistance Genes in Broiler Chickens in Tunisia
Simple Summary The extensive use of colistin in livestock is recognized as the main cause of the emergence of colistin resistance in Gram-negative bacteria. This phenomenon represents a public health concern, as colistin is one of the last-resort antibiotics against multidrug-resistant deadly infections in human medicine. In the present survey, DNA extracted from cloacal swabs from 195 broiler chickens in Tunisia was tested by PCR for the ten mobilized colistin resistance (mcr) genes known so far. Of the 195 animals tested, 81 (41.5%) were mcr-1 positive. These results confirm the urgent nature of antimicrobial resistance in the Tunisian poultry sector and suggest the need for cautious use of colistin in the veterinary field. Colistin is a polymyxin antibiotic that has been used in veterinary medicine for decades, as a treatment for enterobacterial digestive infections as well as a prophylactic treatment and growth promoter in livestock animals, leading to the emergence and spread of colistin-resistant Gram-negative bacteria and to a great public health concern, considering that colistin is one of the last-resort antibiotics against multidrug-resistant deadly infections in clinical practice. Previous studies performed on livestock animals in Tunisia using culture-dependent methods highlighted the presence of colistin-resistant Gram-negative bacteria. In the present survey, DNA extracted from cloacal swabs from 195 broiler chickens from six farms in Tunisia was tested via molecular methods for the ten mobilized colistin resistance (mcr) genes known so far. Of the 195 animals tested, 81 (41.5%) were mcr-1 positive. All the farms tested were positive, with a prevalence ranging from 13% to 93%. These results confirm the spread of colistin resistance in livestock animals in Tunisia and suggest that the investigation of antibiotic resistance genes by culture-independent methods could be a useful means of conducting epidemiological studies on the spread of antimicrobial resistance
Plant bioactive molecules bearing glycosides as lead compounds for the treatment of fungal infection: A review
Despite therapeutic advancement in the treatment of fungal infections, morbidity and mortality caused by these infections are still very high. There are approximately 300 fungal species that are infectious and can cause a variety of diseases. At present, several synthetic antifungal drugs are in clinical practice, many of them, however, are vulnerable to multidrug-resistant strains of microbes, and thus compromising the overall treatment outcomes. Glycosides are naturally occurring plant secondary metabolites with important therapeutic potential and clinical utility. The aim of this review was to focus on the antifungal effects of glycosides in preclinical studies with possible mechanism(s) wherein described. Published research show significant susceptibility of different fungi towards phytoglycosides, mediated through multiple mechanisms. Further detailed studies are needed to explain the clinical applications and limitations of these glycosides
Longitudinal changes in functional connectivity of cortico-basal ganglia networks in manifests and premanifest huntington's disease
Huntington's disease (HD) is a genetic neurological disorder resulting in cognitive and motor impairments. We evaluated the longitudinal changes of functional connectivity in sensorimotor, associative and limbic cortico-basal ganglia networks. We acquired structural MRI and resting-state fMRI in three visits one year apart, in 18 adult HD patients, 24 asymptomatic mutation carriers (preHD) and 18 gender- and age-matched healthy volunteers from the TRACK-HD study. We inferred topological changes in functional connectivity between 182 regions within cortico-basal ganglia networks using graph theory measures. We found significant differences for global graph theory measures in HD but not in preHD. The average shortest path length (L) decreased, which indicated a change toward the random network topology. HD patients also demonstrated increases in degree k, reduced betweeness centrality bc and reduced clustering C. Changes predominated in the sensorimotor network for bc and C and were observed in all circuits for k. Hubs were reduced in preHD and no longer detectable in HD in the sensorimotor and associative networks. Changes in graph theory metrics (L, k, C and bc) correlated with four clinical and cognitive measures (symbol digit modalities test, Stroop, Burden and UHDRS). There were no changes in graph theory metrics across sessions, which suggests that these measures are not reliable biomarkers of longitudinal changes in HD. preHD is characterized by progressive decreasing hub organization, and these changes aggravate in HD patients with changes in local metrics. HD is characterized by progressive changes in global network interconnectivity, whose network topology becomes more random over time. Hum Brain Mapp, 2016. © 2016 Wiley Periodicals, Inc
CZT-Based Harmonic Analysis in Smart Grid Using Low-Cost Electronic Measurement Boards
This paper validates the use of a harmonic analysis algorithm on a microcontroller to perform measurements of non-stationary signals in the context of smart grids. The increasing presence of electronic devices such as inverters of distributed generators (DG), power converters of charging stations for electric vehicles, etc. can drain non-stationary currents during their operation. A classical fast Fourier transform (FFT) algorithm may not have sufficient spectral resolution for the evaluation of harmonics and inter-harmonics. Thus, in this paper, the implementation of a chirp-Z transform (CZT) algorithm is suggested, which has a spectral resolution independent from the observation window. The CZT is implemented on a low-cost commercial microcontroller, and the absolute error is evaluated with respect to the same algorithm implemented in the LabVIEW environment. The results of the tests show that the CZT implementation on a low-cost microcontroller allows for accurate measurement results, demonstrating the feasibility of reliable harmonic analysis measurements even in non-stationary conditions on smart grids
Analysis of the mechanical performance of the 4.2 m long MQXFA magnets for the Hi-Lumi LHC Upgrade
Under the U.S. High Luminosity LHC Accelerator Upgrade Project (HL-LHC AUP),
the 150 mm bore, high-field Nb3Sn low-\b{eta} MQXFA quadrupole magnets are
being fabricated, assembled and tested, in the context of the CERN
Hi-Luminosity LHC (HL-LHC) upgrade. These magnets have 4.2 m magnetic length
and 4.56 m long iron yoke. To date, eight MQXFA magnets have been tested. One
of the magnets additionally underwent a successful endurance test with 40
triggered quenches, and two magnets did not perform as expected. This work
summarizes for the first time the available strain gauge data from eight
identical Nb3Sn MQXFA tested magnets, focusing on the endurance test, and on a
possible cause of underperformance of the two magnets that did not pass the
vertical test. We applied methods to prevent this from happening in future
MQXFA magnets, which shown to be effective for last two tested magnets
Toward an integrative socio-cognitive approach in autism spectrum disorder: NEAR method adaptation—study protocol
BackgroundThe cognitive impairments exhibited by people with ASD, threaten the development of social skills that are essential for establishing and maintaining harmonious social relationships. Cognitive remediation and social skills training are now considered as crucial therapeutic approaches in the management of these disorders. Several programs have already been validated and have shown improvements in social skills or cognitive performance. However, the effects of these training methods seem to be difficult to generalize to other everyday life. The aim of our study is to alleviate cognitive and social deficiencies by using a socio-cognitive framework to adapt the Neuropsychological Educational Approach to Remediation (NEAR) method for adolescents with ASD.Methods/designAdolescents meeting the DSM-5 criteria for ASD, older than 13 years, and following a regular school curriculum will be recruited from clinical population at the Child and Adolescent Psychiatry in Razi University Hospital-Manouba- Tunisia. Our study is an open and non-randomized controlled trial including 30 patients: NEAR group / control group. The NEAR method combines computerized cognitive exercises and bridging groups inspired from cognitive behavioral therapy. NEAR group will be divided into three groups of five patients each. The duration of the sessions will vary according to the capacities of the participants and the exchanges between them (about 60–120 min). In our study, bridging groups will be amended by adding other tasks including planning role plays and scenarios of problematic social situations in autism, taking into account cultural particularities in order to promote social skills. Computerized exercises will be enriched by adding other tasks aiming to improve the recognition and expression of facial emotions by using digital videos and photographs expressing the six basic emotions. The duration of the program will be about 6 months. All selected patients will have an assessment of cognitive function: social cognition, neurocognition and pragmatic skills, social skills, self-esteem and global functioning at baseline, 1 week after the end of the NEAR program and 6 months later.ConclusionThis adaptive program is a promising socio-cognitive intervention that create new perspectives for adolescents with autism spectrum disorder
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