•Technological advancements in functionally graded materials.•Comparison of various homogenization schemes.•Review on analysis of functionally graded structures.•Suggested future scope in the ...analysis of functionally graded structures.•Review on various fabrication methods of functionally graded materials along their mechanical and tribological performance.
This paper discourses an overview of the recent advancements in functionally graded materials (FGMs) research. The paper also disseminates on the key researches that are carried out in the scientific community on the development of manufacturing and modelling of functionally graded materials. The rationale of the current work is to emphasize the selection of materials, processing techniques and analytical modelling and applications of FGMs. Alongside, challenges involved in developing these materials towards various aspects of scientific and technological fields will be addressed.
As major historical periods such as Stone Age, Bronze Age, and Iron Age, the development of new materials was the fundamental to all the periods. In the present investigation, a new hybrid composite ...with epoxy as a resin and reinforcing both biowaste (jute) and traditional fiber (glass) as continues layered mat composites and also study experimentally the effect of the stacking sequence on tensile, flexural, and interlaminar shear properties. Composites were prepared by using hand lay-up technique. All the laminates were prepared with a total of four piles, by varying the position of glass and jute. One group of all jute and glass laminate was also fabricated for comparison purpose. Specimen preparation and testing were carried out as per ASTM standards. Tests were conducted on INSTRON H10KS Material Test System at room temperature using automatic data acquisition software. The results indicated that the jute fiber and hybrid composite give encouraging results when compared with the neat epoxy. The morphologies of the composites are also studied by scanning electron microscope.
The aim of the present work was to study the effect of fiber surface treatment on the structural, thermal and mechanical properties of luffa fiber and its composites. Fibers were treated with alkali ...(5% conc.), benzoyl chloride, and potassium permanganate (KMnO4) (0.05%) at room temperature. The untreated and treated fibers were characterized and morphologically analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The effect of fiber surface modification on the mechanical properties such as tensile strength, flexural strength, ILSS, and impact strength of the composites were investigated. It is observed that chemically treated Luffa cylindrica-reinforced epoxy composites significantly improved the mechanical properties of the composite. The maximum strength properties were found with benzoyl chloride-treated fiber-reinforced composite.
The aim of this paper is to replace the traditional fiber composites with a natural-fiber composite in perception of tribological and mechanical accepts. A systematic study has been carried out to ...investigate jute fiber properties when incorporated into epoxy matrix. Thermogravimetric analysis has also been carried out for jute and epoxy for thermal property analysis. For a comparison purpose epoxy and glass fiber composites are prepared. The investigation reveals that, due to incorporation of jute into polymer epoxy shows better properties than the resins alone; but the properties are inferior to those of glass reinforced in terms of mechanical. When considering the tribological application, the jute fiber shows superior properties than neat and glass-reinforced epoxy composites. The worn out samples were studied using scanning electron microscope.
Cenosphere is a ceramic-rich industrial waste produced during burning of coal in thermal power plants. This study deals with the effect of cenosphere as particulate filler on mechanical behaviour of ...woven jute-glass hybrid composites. The hybrid composite consists of jute and glass fiber as reinforcement and epoxy as matrix. The conventional hand lay-up technique is used to prepare composite specimens. Cenosphere of different weight percentage (5, 10, 15 and 20 wt%) was added to the hybrid composite. The samples were tested as per ASTM standards for their mechanical and flexural properties to establish the effect of filler content. It is found that the mechanical properties are significantly influenced by addition of waste ceramic filler cenosphere up to 15 wt% and increases the tensile, flexural and interlaminar shear strength by 90.47%, 24.32% and 16.75%, respectively, in comparison to unfilled composite. The morphologies of the composites studied by scanning electron microscope indicate good dispersibility of cenosphere in the matrix, which in turn improves the strengths appreciable.
Background and aim: In acute liver failure (ALF), the brain is exposed to high levels of ammonia. Human studies defining the clinical significance of ammonia in ALF are lacking. This prospective ...study evaluated the relationship of arterial ammonia levels at admission to complications and survival among patients with ALF. Methods: Eighty consecutive ALF patients admitted from March 2001 to December 2003 were followed up until death or complete recovery. All had arterial ammonia estimation at admission (enzymatic method). Logistic regression analysis was performed to identify independent predictors of mortality. Results: Forty two (52.5%) patients died. Non-survivors had significantly higher median ammonia levels than survivors (174.7 v 105.0 μmol/l; p<0.001). An arterial ammonia level of ⩾ 124 μmol/l was found to predict mortality with 78.6% sensitivity and 76.3% specificity, and had 77.5% diagnostic accuracy. Patients with higher ammonia levels also developed more complications, including deeper encephalopathy (p = 0.055), cerebral oedema (p = 0.020), need for ventilation (p<0.001), and seizures (p = 0.006). Logistic regression analysis showed that pH, presence of cerebral oedema, and arterial ammonia at admission were independent predictors of mortality (odds ratios 6.6, 12.6, and 10.9, respectively). Incorporating these variables, a score predicting mortality risk at admission was derived: 2.53 + 2.91 ammonia + 2.41 oedema + 1.40 pH, where ammonia is scored as 0 (if <124 μmol/l) or 1 (if ⩾124 μmol/l); oedema is scored as 0 (absent) or 1(present); and pH is scored as 1 (if ⩽7.40) or 0 (if >7.40). Levels of partial pressure of ammonia were equally correlated with outcome. Conclusion: Arterial ammonia at presentation is predictive of outcome and can be used for risk stratification. Ammonia lowering therapies in patients with ALF should be evaluated.
Background & Aims Oxidative stress has been implicated in the pathophysiology of chronic pancreatitis (CP). We evaluated the effects of antioxidant supplementation on pain relief, oxidative stress, ...and antioxidant status in patients with CP. Methods In a placebo-controlled double blind trial, consecutive patients with CP were randomized to groups that were given placebo or antioxidants for 6 months. The primary outcome measure was pain relief, and secondary outcome measures were analgesic requirements, hospitalization, and markers of oxidative stress (thiobarbituric acid-reactive substances TBARS) and antioxidant status (ferric-reducing ability of plasma FRAP). Results Patients (age 30.5 ± 10.5 years, 86 male, 35 alcoholic, and 92 with idiopathic CP) were assigned to the placebo (n = 56) or antioxidant groups (n = 71). After 6 months, the reduction in the number of painful days per month was significantly higher in the antioxidant group compared with the placebo group (7.4 ± 6.8 vs 3.2 ± 4, respectively; P < .001; 95% CI, 2.07, 6.23). The reduction in the number of analgesic tablets per month was also higher in the antioxidant group (10.5 ± 11.8 vs 4.4 ± 5.8 respectively; P = .001; 95% CI, 2.65, 9.65). Furthermore, 32% and 13% of patients became pain free in the antioxidant and placebo groups, respectively ( P = .009). The reduction in the level of TBARS and increase in FRAP were significantly higher in the antioxidant group compared with the placebo group (TBARS: placebo 1.2 ± 2.7 vs antioxidant 3.5 ± 3.4 nmol/mL; P = .001; 95% CI 0.96, 3.55; FRAP: placebo −5.6 ± 154.9 vs antioxidant 97.8 ± 134.9 μMFe+2 liberated, P = .001, 95% CI 44.98, 161.7). Conclusions Antioxidant supplementation was effective in relieving pain and reducing levels of oxidative stress in patients with CP.
The biocomposite (PMMA/Chitosan) is synthesized by combining MMA as a monomer and modified chitosan as a filler material extracted from oyster shell powder. The method used for extraction includes ...deproteinization, demineralization, and deacetylation. The synthesized biomaterial is characterized by using different techniques. The DLS shows the uniform distribution of particles of filler materials, FTIR analysis peaks confirm the formation of biocomposite on interaction of Chitosan with MMA, X-ray diffraction study shows a strong peak at 2θ = 10.3° indicating the formation of a stable biocomposite,SEM image indicates the uniform distribution of fillers, andTGA indicates that the biocomposite is stable up to 500 °C and after that weight loss is observed. The analysis result indicates that the biopolymer chitosan forms a covalent bond with the PMMA matrix and forms a porous structure. The thermal stability of the synthesised biomaterial is gradually enhanced by the increase in the concentration of chitosan microscopic particles at the surface of the matrix, particularly at low thermal expansion. The synthesised novel biomaterial can be used successfully in various applications, such as flexible electronic printing and organic printing. The synthesized biomaterial is highly effective for drug release in the targeted drug delivery system.
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