Single-mode D-shaped optical fiber sensor for the refractive index monitoring of liquid

A new fabrication method is introduced for the production of D-shaped optical fiber. A mechanical end and edge polishing system with aluminum oxide polishing film is utilized to perform sequential polishing on one side (lengthwise) of single-mode optical fiber in order to obtain a D-shaped cross section. Adjusting specific mechanical parameters allows for control of the volume of the D-shaped zone, while the fiber surface smoothness is governed by selection of polishing film grit size. To meet the accuracy and repeatability requirements, optical power loss is monitored during the entire polishing process in situ and in real time. This proposed technique possesses advantages of rapidity, safety, simplicity, repeatability and stability with high precision in comparison with contemporary methods for production. Sensor performance tests on the fiber reveal a linear response with linearity up to R² = 0.984 for surrounding refractive index in the range of 1.320–1.342 refractive index, which corresponds to different concentrations of the glucose solution test environment. The produced D-shaped optical fiber has potential sensing and monitoring applications in chemical, environmental, biological and biochemical fields.     

A dynamic modeling to measure lean performance within lean attributes

In today’s competitive world lean manufacturing has become an important “role model” for two groups: academics and practitioners. Many organizations around the world have attempted to implement it but the lack of a clear understanding of the main attributes to leanness, lean performance and its measurement contribute to the failure of lean practices. It therefore seems necessary to provide a way to evaluate the impact of lean attributes using an approach to determine the criteria and key factors of leanness. Although there are numerous theoretical and practical studies that address lean tools and techniques, few studies focus systematically on measuring the influence of lean attributes on leanness. To fill the current gap, this paper presents an innovative approach to measure the value of the influence of lean attributes on manufacturing systems by using fuzzy membership functions. A lean attributes score is finally calculated to give managers and decision makers a real insight into the leanness level and to further improve it by acting appropriately in the manufacturing system. The model is dynamic, flexible, feasible, and easy to follow and implement. It enables a systematic measurement of the influence of lean attributes by producing a final integrated unit score.     

Optimization of Serine Protease Purification from Mango (Mangifera indica cv. Chokanan) Peel in Polyethylene Glycol/Dextran Aqueous Two Phase System

Mango peel is a good source of protease but remains an industrial waste. This study focuses on the optimization of polyethylene glycol (PEG)/dextran-based aqueous two-phase system (ATPS) to purify serine protease from mango peel. The activity of serine protease in different phase systems was studied and then the possible relationship between the purification variables, namely polyethylene glycol molecular weight (PEG, 4000-12,000 g·mol(-1)), tie line length (-3.42-35.27%), NaCl (-2.5-11.5%) and pH (4.5-10.5) on the enzymatic properties of purified enzyme was investigated. The most significant effect of PEG was on the efficiency of serine protease purification. Also, there was a significant increase in the partition coefficient with the addition of 4.5% of NaCl to the system. This could be due to the high hydrophobicity of serine protease compared to protein contaminates. The optimum conditions to achieve high partition coefficient (84.2) purification factor (14.37) and yield (97.3%) of serine protease were obtained in the presence of 8000 g·mol(-1) of PEG, 17.2% of tie line length and 4.5% of NaCl at pH 7.5. The enzymatic properties of purified serine protease using PEG/dextran ATPS showed that the enzyme could be purified at a high purification factor and yield with easy scale-up and fast processing.     

Preparation, Characterization and Thermal Degradation of Polyimide (4-APS/BTDA)/SiO(2) Composite Films

Polyimide/SiO(2) composite films were prepared from tetraethoxysilane (TEOS) and poly(amic acid) (PAA) based on aromatic diamine (4-aminophenyl sulfone) (4-APS) and aromatic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride) (BTDA) via a sol-gel process in N-methyl-2-pyrrolidinone (NMP). The prepared polyimide/SiO(2) composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The FTIR results confirmed the synthesis of polyimide (4-APS/BTDA) and the formation of SiO(2) particles in the polyimide matrix. Meanwhile, the SEM images showed that the SiO(2) particles were well dispersed in the polyimide matrix. Thermal stability and kinetic parameters of the degradation processes for the prepared polyimide/SiO(2) composite films were investigated using TGA in N(2) atmosphere. The activation energy of the solid-state process was calculated using Flynn-Wall-Ozawa's method without the knowledge of the reaction mechanism. The results indicated that thermal stability and the values of the calculated activation energies increased with the increase of the TEOS loading and the activation energy also varied with the percentage of weight loss for all compositions.     

Evaluation of Antioxidant Properties and Mineral Composition of Purslane (Portulaca oleracea L.) at Different Growth Stages

The main objective of this research was to appraise the changes in mineral content and antioxidant attributes of Portulaca oleracea over different growth stages. The antioxidant activity was measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP) assays. The iodine titration method was used to determine the ascorbic acid content (AAC). DPPH scavenging (IC(50)) capacity ranged from 1.30 ± 0.04 to 1.71 ± 0.04 mg/mL, while the ascorbic acid equivalent antioxidant activity (AEAC) values were 229.5 ± 7.9 to 319.3 ± 8.7 mg AA/100 g, total phenol content (TPC) varied from 174.5 ± 8.5 to 348.5 ± 7.9 mg GAE/100 g. AAC 60.5 ± 2.1 to 86.5 ± 3.9 mg/100 g and FRAP 1.8 ± 0.1 to 4.3 ± 0.1 mg GAE/g. There was good correlation between the results of TPC and AEAC, and between IC(50) and FRAP assays (r(2) > 0.9). The concentrations of Ca, Mg, K, Fe and Zn increased with plant maturity. Calcium (Ca) was negatively correlated with sodium (Na) and chloride (Cl), but positively correlated with magnesium (Mg), potassium (K), iron (Fe) and zinc (Zn). Portulaca olerecea cultivars could be used as a source of minerals and antioxidants, especially for functional food and nutraceutical applications.     

Mine blast algorithm: A new population based algorithm for solving constrained engineering optimization problems

A novel population-based algorithm based on the mine bomb explosion concept, called the mine blast algorithm (MBA), is applied to the constrained optimization and engineering design problems. A comprehensive comparative study has been carried out to show the performance of the MBA over other recognized optimizers in terms of computational effort (measured as the number of function evaluations) and function value (accuracy). Sixteen constrained benchmark and engineering design problems have been solved and the obtained results were compared with other well-known optimizers. The obtained results demonstrate that, the proposed MBA requires less number of function evaluations and in most cases gives better results compared to other considered algorithms.     

Mechanical properties of polypropylene composite reinforced with oil palm empty fruit bunch pulp

In this study, oil palm empty fruit bunch (EFB) pulp was used as reinforcing agent in polypropylene composite. EFB pulp was prepared using soda pulping with different concentrations of sodium hydroxide (NaOH) solution. Overall, the tensile and flexural properties specifically the strength and the toughness showed improvement as the NaOH content in the treatment was increased. This was attributed to lower probability for EFB pulp to agglomerate and the production of higher aspect ratio pulp fibers. Scanning electron microscopy analysis showed evidence of the reduction in EFB bundles diameter after NaOH treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010