Hybridization of Polyester/Banana stem Fiber and Cow horn particulate composite for possible production of a military helmet

Author(s):  
M.Y Abdulrahim ◽  
D. S Yawas ◽  
R.A Mohammed ◽  
M.O Afolayan
2011 ◽  
Vol 695 ◽  
pp. 170-173 ◽  
Author(s):  
Voravadee Suchaiya ◽  
Duangdao Aht-Ong

This work focused on the preparation of the biocomposite films of polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC) prepared from agricultural waste, banana stem fiber, and commercial microcrystalline cellulose, Avicel PH 101. Banana stem microcrystalline cellulose (BS MCC) was prepared by three steps, delignification, bleaching, and acid hydrolysis. PLA and two types of MCC were processed using twin screw extruder and fabricated into film by a compression molding. The mechanical and crystalline behaviors of the biocomopsite films were investigated as a function of type and amount of MCC. The tensile strength and Young’s modulus of PLA composites were increased when concentration of MCC increased. Particularly, banana stem (BS MCC) can enhance tensile strength and Young’s modulus of PLA composites than the commercial MCC (Avicel PH 101) because BS MCC had better dispersion in PLA matrix than Avicel PH 101. This result was confirmed by SEM image of fractured surface of PLA composites. In addition, XRD patterns of BS MCC/PLA composites exhibited higher crystalline peak than that of Avicel PH 101/PLA composites


2020 ◽  
Vol 22 (Supplement_N) ◽  
pp. N131-N131
Author(s):  
Massimo Bolognesi

Abstract The Pickelhaube Sign is today recognized as a novel Echocardiographic Risk Marker for Malignant Mitral Valve Prolapse Syndrome. Mitral Valve Prolapse (MVP) has long been recognized to be a relatively common valve abnormality in the general population. Patients with relatively non-specific symptoms and asymptomatic athletes who have MVP still represent an important clinical conundrum for any physician involved in preventive medicine and sports screening. Although cardiac arrhythmias and/or cardiac death are an undesirable problem in MVP patients, when these subjects were studied with Holter Electrocardiogram (ECG) monitoring a prevalence of ventricular arrhythmias up to 34% was observed, with premature ventricular contractions as the most common pattern (66% of cases). At this regard a paper by Anders et al. described a series of cases that suggest that even clinically considered benign cases of MVP in young adults may cause sudden and unexpected death. However, cardiac arrest and Sudden Arrhythmic Cardiac Death (SCD) resulted in rare events only in patients with MVP based on data from a community study. A middle-aged athletic male who has been practicing competitive cycling for about 20 years came to our Sports Medicine Centre to undergo screening of sports preparation for competitive cycling and the related renewal of certification for participation in sports competitions. This athlete was always considered suitable in previous competitive fitness assessments performed in other sports medicine centers. His family history was unremarkable, as well as his recent and remote pathological anamnesis. The physical examination revealed a 3/6 regurgitation heart murmur with a click in the mid late systole. Previous echocardiographic examinations revealed a MVP which was considered benign with mild not relevant mitral regurgitation. He did not complain of symptoms such as dyspnoea or heart palpitations during physical activity. The resting ECG showed negative T waves in the inferior limb leads, and the stress test showed sporadic premature ventricular beats (a couple) with right bundle branch block morphology. An echocardiogram confirmed the presence of a classic mitral valve prolapse with billowing of both mitral leaflets, associated with a mild to moderate valve regurgitation. The TDI exam at the level of the lateral mitral annulus showed a high-velocity mid-systolic spike like a Pickelhaube sign, i.e. spiked German military helmet morphology. Consequently, an in-depth diagnostic imaging with cardiac magnetic resonance imaging was proposed, but the athlete refused it, both because he was totally asymptomatic and above all because he would be forced to pay a considerable amount of money as the examination is not guaranteed by the Italian National Health Service. In conclusion, the athlete remained sub judice as for competitive suitability, Finally, the question is: does MVP really cause sudden death? Is it enough to detect the Pickelhaube signal by echocardiography to stop this athlete? Let us bear in mind that this athlete was asymptomatic, and he had not had any trouble during exercise and maximal effort for many years. Why must we declare him unsuitable to do competitive sports?


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