OPTIMUM WORKING CONDITIONS FOR VARIABLE WIDTH PLOUGHS

In this paper, a few assessments of the optimal parametric combinations in the operating regime of agricultural aggregates with ploughs of variable width are made. The starting point was from a classic expression of the tillage draft force required for traction. In order to find optimal points, some problems of constrained extreme have been formulated. Extremes provided by the optimal working width and speed have been found. Such optimal points have existed in the literature, for about half a century. Using these theoretical estimates of the optimal points sought, assessments of the possibilities for their experimental validation were made. Basic conditions for an experimental plan are formulated to highlight such optimal points.

Priority Assessment of Key Factors of IMO-MSC/Circular.834 for Ship Engine Room Safety and Efficiency Based on Human Aspects

International Maritime Organization (IMO) has published technical circular (MSC/Circular. 834) including nonmandatory guidelines with five main criteria about engine room layout, design, and arrangement. The purpose of this study is to present the most important priority criteria of seafarers about engine room design according to the criteria from IMO MSC/Circular.834 guidelines. Since there are no obligations, the priority and importance of these criteria are not clearly emphasized. Therefore, the determination of seafarers’ priorities for arrangement in terms of safety and efficiency become important to make decision. For this, fuzzy Analytic Hierarchy Process (AHP) technique, which is one of the most used fuzzy Multiple Criteria Decision Making (MCDM)methods is employed. Introduction Maritime transportation, known for oldest and widespread transportation around the world, with 11 billion tons weight and 80% rate of world trade volume (UNCTAD 2019). Maritime transportation has many components and one of the most important and effective parts of these components are ships and seafarers. Because of the difficulty of ship conditions, ships should be present optimum working conditions for seafarers in order to achieve effective and safe operations on board. At the present time, there are previous studies about the difficulty of working studies on board. It is a scientific and cultural fact that seafarers are under higher risk of working conditions comparing to other jobs (Bloor et al. 2000; Havold 2005; Hetherington et al. 2006; Mallam et al. 2015). Due to this reason, International Maritime Organization (IMO) has made various regulations for years in order to improve seafarers’ safety and efficiency on board. One of the goals of these regulations is to design optimum working conditions on board for seafarers. Based on complex structure and having various danger conditions, engine room design is considerable to ensure safety and efficiency for engine room department seafarers.

Apical reference point - A clinical perspective

The clinicians face various challenges in trying to find the optimum working length during root canal treatment. Unless proper biomechanical preparation up to the apical limit is done, reinfection of the canal occurs. Apical reference point must be measured with at most care as to avoid any damage to the surrounding periodontal tissues during the treatment.

Immobilization of Camel Liver Catalase on Nanosilver-Coated Cotton Fabric

Nanoparticles have the advantage of a superior surface area to volume ratio, and thus such materials are useful for enzyme immobilization. A silver nanoparticle coated cotton fabric (AgNp-CF) is used to immobilize camel liver catalase in the present work. The effect of loading levels of AgNp inside cotton fabrics on the immobilization of catalase was investigated. The results revealed that a 6 mL loading level of AgNp precursor (silver nitrate, 2 mM) at pH 8 showed the maximum immobilization efficiency (76%). The morphological properties of the cotton fabric (CF), AgNp-CF and AgNp-CF-catalase were characterized by SEM. The reusability of the immobilized enzyme was tested over ten reuses to show a 67% retained function of its initial activity. Compared with the soluble enzyme’s working pH (6.5), a rather broader working pH (6.5–7.0) was observed for the immobilized catalase. Additionally, the optimum working temperature increased from 30 for the soluble enzyme to 40 °C for the immobilized one, indicating thermal stability. The free and immobilized catalase enzyme’s Km values were 22.5 and 25 mM H2O2, respectively, reflecting the enzyme’s effective properties. The inhibitory effect of metal ions on the enzyme activity was higher toward soluble catalase than the immobilized catalase. This work has developed a method for immobilizing catalase to be useful for several applications.

Microencapsulation of Erlotinib and Nanomagnetite Supported in Chitosan as Potential Oncologic Carrier

Microcapsules (MC) based on chitosan (CH) and including nano-magnetite and erlotinib were synthesized. The microparticles were characterized by SEM, FT-IR and TGA. The percentage of encapsulation was determined, as well as its microbiological activity. Finally, the effectiveness of the formulation was evaluated in terms of cell viability and/or toxicity when compared with the reference drug. The formulation used to prepare the microcapsules showed some bacteriostatic properties. The characterization of microcapsules exhibited amorphous spherical shape and average size of 1.29, 1.58 and 1.62 mm for chitosan, chitosan + nanomagnetite and chitosan + nanomagnetite + erlotinib, respectively. The infrared spectra showed characteristic bands of the erlotinib and magnetite, confirming its internalization. The thermogravimetric analyzes indicated that the materials do not undergo changes at optimum working temperatures. The HPLC analysis showed a 52% of encapsulation. Finally, the formulation probed had lower effectiveness and less cytotoxicity, than the drug without encapsulating “in vitro” studies. For that reason several assays are in progress.