Experimental analysis of the defects of drilling woven CFRP

International audienceIn this paper, experimental analysis has been done to study delamination phenomenon when drilling 4 shaft satin weave carbon fiber and epoxy matrix using twist drill. The composite is exposed to generate damage during processing due to delamination phenomenon. It was found that the increase of the feed rate was related to the apparition of superficial defects. Indeed, this increase gave birth to new types of drilling defects

Evaluation expérimentale du comportement d'un composite carbone/époxy en usinage

Les matériaux composites sont largement utilisés.Mais en raison de la complexité des phénomènes présents dans la zone de coupe, les connaissances actuelles sur leur usinage sont limitées et empêchent leur utilisation optimale. L'objectif de cette étude est d'analyser le comportement du composite carbone/époxy durant l'usinage. Des essais de coupe orthogonale et de détourage ont été réalisés sur des composites unidirectionnels. Trois orientations de fibres et différentes valeurs pour chaque paramètre de coupe ont été étudiées pour dégager les tendances d'évolution des conditions de coupe

Intraspecifična karakterizacija izolata Vibrio alginolyticus prikupljenih iz sustava akvakulture i morskih biotopa u Tunisu korištenjem PCR-RFLP, ECP i OMPS profiliranja.

A total of 54 presumptive Vibrio alginolyticus strains isolated from a variety of Tunisian marine biotopes, such as seawater, sediment samples from some bathing areas, and aquaculture farms, were characterized and identified by several biochemical tests. DNA polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, extracellular products (ECP) and outer membrane protein (OMP) profiling were used to evaluate their usefulness as a tool to investigate the Vibrio alginolyticus diversity within this complex group. Results showed that there is great heterogeneity in the diversity observed via the PCR-RFLP method related to the number of genotypes generated by the two enzymes SduI and FaqI tested. This heterogeneity was observed not only according to the origin (seawater, sediment, fish and bivalve aquaculture farms) but also within the same type of sample. The two other methods, ECP and OMP resulted in 32 and 26 profiles, respectively. The discriminatory index determined in this study highlighted the good ability of the PCR-RFLP method to discriminate similar V. alginolyticus strains.Ukupno 54 vjerojatna soja Vibrio alginolyticus izolirana su iz raznih morskih biotopa u Tunisu, iz morske vode i sedimenta s nekoliko kupališta i uzgajališta te su karakterizirani i identificirani pomoću nekoliko biokemijskih testova. Istraživana je prikladnost metoda kao što su analiza polimorfizma duljine restrikcijskih fragmenata PCR proizvoda (PCR-RFLP), profiliranje izvanstaničnih proizvoda (ECP) i proteina vanjske membrane (OMP) kao alata za istraživanje raznolikosti Vibrio alginolyticus unutar ove složene skupine. Rezultati su pokazali da postoji velika heterogenost u raznolikosti određenoj metodom PCR-RFLP koja se odnosila na broj genotipova generiranih s dva testirana enzima SduI i FaqI. Ova heterogenost je uočena ne samo prema podrijetlu (morska voda, sediment, uzgajališta riba i školjkaša), već i unutar istog tipa uzorka. Druge dvije metode, ECP i OMP rezultirale su s 32, odnosno 26 profila. Indeks diskriminacije utvrđen u ovoj studiji istaknuo je dobru sposobnost PCR-RFLP metode u razlikovanju sličnih sojeva V. alginolyticus

Tobacco Smoking, Secondhand Smoke Exposure and Cessation Perceptions by Dental Students in Al Madinah, a Conservative Saudi Society

Objective: To explore the prevalence of tobacco use and secondhand smoke (SHS) exposure in dental students and to investigate their perceptions on the role of dentists in tobacco cessation activities. Material and Methods:  A questionnaire-based study was conducted in a public university in Al Madinah, Saudi Arabia. The questionnaire investigated demographic factors, tobacco use practices, SHS exposure, and student perceptions of tobacco cessation activities. Descriptive statistics and statistical significance of differences between demographic groups were calculated. Results: A total of 228 students participated with 43.0% (n=98) males and 57.0% (n=130) females. A proportion of 30.7% (n=70) of the participants smoked tobacco, and these constituted 51 males (73%) and 19 females (27%). Only 39 students (15 females and 24 males) indicated their method of tobacco use, which was mainly cigarettes and waterpipes. One in two students was exposed to SHS. Non-smokers had better awareness of the health hazards of SHS (p<0.001), and were more likely to adopt tobacco cessation activities recommended by dentists (p<0.05). Conclusion:  A substantial proportion of dental students in a very conservative religious area smoke tobacco and are exposed to SHS. Their perceptions of the harms of SHS and attitudes on cessation need improvement. The influence of culture and religion in shaping health risk behaviors in conservative communities needs to be verified

Experimental study of thrust force and surface quality when drilling hybrid stacks

International audienceIncreasing aircrafts’ productivity and reducing their riveting time have created the need of one-shot drilling of dissimilar materials. The present work had followed this strategy on 4 shaft satin weave carbon fiber and epoxy matrix (AS-4 woven CFRP) and aluminum alloy (AA 2189) in order to study the effect of drilling direction on Al and carbon fiber reinforced polymer thrust force evolution and holes’ quality. It presents a comparison between CFRP, CFRP/Al, and Al/CFRP results using the same drilling tool and cutting parameters to understand the influence of adding metal layers on CFRP drilling defects. It was observed that the increase of the thrust force is related to cutting parameters. It causes thermal degradation of composite matrix when drilling CFRP/Al, and it impacts the aluminum surface roughness. One-shot drilling strategy does not affect thrust force evolution whenever the layers’ position in the stack. Drilling defects exist especially in the composite part such as uncut fibers, chipping, and spalling. It was found that the cutting speed had the dominant influence on surface damage. Holes’ quality differs from one configuration to another. Adding Al layer on the top reduces seriously the composite drilling defects and causes groove in the Al holes. Composite matrix smearing was observed when drilling CFRP/Al. It seems that drilling CFRP sheet between to supports improves composite holes’ quality

Experimental investigation of drilling damage and stitching effects on the mechanical behavior of carbon/epoxy composites

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Genetic spectrum of retinal dystrophies in Tunisia

We report the molecular basis of the largest Tunisian cohort with inherited retinal dystrophies (IRD) reported to date, identify disease-causing pathogenic variants and describe genotype-phenotype correlations. A subset of 26 families from a cohort of 73 families with clinical diagnosis of autosomal recessive IRD (AR-IRD) excluding Usher syndrome was analyzed by whole exome sequencing and autozygosity mapping. Causative pathogenic variants were identified in 50 families (68.4%), 42% of which were novel. The most prevalent pathogenic variants were observed in ABCA4 (14%) and RPE65, CRB1 and CERKL (8% each). 26 variants (8 novel and 18 known) in 19 genes were identified in 26 families (14 missense substitutions, 5 deletions, 4 nonsense pathogenic variants and 3 splice site variants), with further allelic heterogeneity arising from different pathogenic variants in the same gene. The most common phenotype in our cohort is retinitis pigmentosa (23%) and cone rod dystrophy (23%) followed by Leber congenital amaurosis (19.2%). We report the association of new disease phenotypes. This research was carried out in Tunisian patients with IRD in order to delineate the genetic population architecture

Erlotinib in Patients with Advanced Non-small Cell Lung Cancer in Middle Eastern Population

Background: Although erlotinib is widely used in the management of non-small cell lung cancer (NSCLC), no prior studies were conducted in Middle Eastern population. Our study aims at evaluating erlotinib prospectively in this population. Patients and Methods: This open-label, prospective, single-arm, multicenter Phase IV clinical trial of erlotinib as single agent evaluated safety and efficacy of Erlotinib in Middle Eastern patients with advanced NSCLC. Results: A total of 56 patients were enrolled in five sites in Saudi Arabia. Majority of patients were males (60%) with median age of 57 years (34–80), Stage IV (98%), and adenocarcinoma (84%). Eastern Cooperative Oncology Group performance Status III (41.1%). Epidermal growth factor receptor (EGFR) mutations were present in 24 patients out of 36 patients tested (67%). The most common reported adverse events (AEs) were rash 36 (64%), diarrhea 29 (52%), fatigue 10 (18%), and anorexia 5 (9%). Grade 4 or 5 AEs were not observed. Complete response was achieved in 2 (3.6%) and overall disease control was 60.8%. Median overall survival (OS) was significantly longer in patients with EGFR mutation than wild type (20 vs. 3 months, P = 0.002). Progression-free survival was 10 months and significantly longer in patients with EGFR mutation than wild type (16 vs. 6 months, P = 0.037). Patients with unknown EGFR status had PSF and OS better than wild-type patients and worse than patients with EGFR mutation. Cox regression analysis showed that older age (P = 0.029, HR 1.064), EGFR wild type (P = 0.014, hazard ratio [HR]: 8.497), and receiving radiation (P = 0.033, HR 6.433) significantly increase risk of death for patients receiving erlotinib. Conclusion: Erlotinib has efficacy and safety profile in Middle Eastern population similar to the reported literature. The empiric use of erlotinib in patients with unknown EGFR status in our patient population is warranted due to high prevalence of the mutation. However, it should not be used in confirmed wild-type disease

Using Coordinated Visual and Verbal Cues in Complex Multimedia Materials to Improve Tactical Learning in Soccer

This study aimed to explore whether the use of coordinated visual and verbal cues in narrated diagrams would support novices in learning soccer scenes. Eighty female university students (Mage = 20 years, SD = 1.2) in physical education (PE) were randomly exposed to four multimedia material versions: (a) simple without cues, (b) simple with cues, (c) complex without cues, and (d) complex with cues. In the non-cued versions, students learned the evolution of soccer scenes via arrow-based diagrams accompanied by oral explanations. In the cued versions, game actions in narrations were spoken with a louder accent (verbal cueing), while at the same time, the corresponding arrows turned red in diagrams (visual cueing). After studying one of the four versions, participants were asked to complete immediate and delayed recall–reconstruction tests, and to indicate their attitudes towards instructional materials. The results demonstrate the instructional benefits of using coordinated dual-modality cues in the complex multimedia material, in terms of immediate (p = 0.03, d = 0.53) and delayed (p = 0.02, d = 0.85) recall performances. The findings encourage soccer teachers to verbalize game actions with a louder accent, while simultaneously coloring the corresponding arrows in the diagram when explaining complex game situations for novices