DEMYSTIFYING SHIP OPERATIONAL AVAILABILITY – AN ALTERNATIVE APPROACH FOR THE MAINTENANCE OF NAVAL VESSELS

Asset availability improvement has been the focus of many studies by various industries for a few decades now, and the defence industry is no exception. To date, there exists no simple and inexpensive high availability solution for the complex naval ships consisting of many interdependent systems and subsystems working in parallel. Any given approach must strike a balance between true needs and economics, an ever-increasing decision-making burden to stakeholders. Nevertheless, there are many ways to approach the problem. In the past, availability has been viewed as complex mathematical calculations and estimates involving defective equipment. The applied approach has not been fully understood nor appealing to most practitioners as well as the majority of stakeholders who continuously complain about the gap between theory and practice. This paper aims to demystify the complex naval ship availability issue, simplified for easy understanding of operators, maintainers and logisticians as well as other stakeholders involved in the maintenance of naval vessels. The stepby-step approach begins with the identification of severe factors involving both human and machinery affecting downtime of naval vessels culminating into the generation of an availability-oriented model, summarized to a simple four-step approach to availability improvement. Practitioners are now able to appreciate their individual contribution towards improving ship availability

Effect of Surface Modification of Polyamide-Based Reverse Osmosis Membranes by Glycerol Monoacrylate–Butyl Acrylate Copolymers on Antifouling

Suppression of membrane fouling is essential for making reverse osmosis (RO) membrane systems more economical. In the present study, we synthesized polymers bearing a glycerol monoacrylate moiety as an antifouling unit and a butyl acrylate moiety as a membrane-adsorbing unit. We modified RO membranes by immersion in solutions of the synthesized copolymers as a simple antifouling method. We evaluated the membrane antifouling performance by assessing its permeability to bovine serum albumin as a foulant. Compared with the pristine membrane, the copolymer-modified RO membrane had a higher normalized water permeability and longer water retention (24 h). This enhancement was attributed to the hydrophilicity of the glycerol monoacrylate moiety, membrane modification by the butyl acrylate moiety, and the formation of intermediate water with a small quantity of nonfreezing water in the polymer, as determined by differential scanning calorimetry

Comparative Cultural Research of as a System : European and Asian Encounters Focused on the Age of Exploration

http://ci.nii.ac.jp/naid/11000655903

Preparation of Chemically Resistant Cellulose Benzoate Hollow Fiber Membrane via Thermally Induced Phase Separation Method

For the first time, we have successfully fabricated microfiltration (MF) hollow fiber membranes by the thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) methods using cellulose acetate benzoate (CBzOH), which is a cellulose derivative with considerable chemical resistance. To obtain an appropriate CBzOH TIPS membrane, a comprehensive solvent screening was performed to choose the appropriate solvent to obtain a membrane with a porous structure. In parallel, the CBzOH membrane was prepared by the NIPS method to compare and evaluate the effect of membrane structure using the same polymer material. Prepared CBzOH membrane by TIPS method showed high porosity, pore size around 100 nm or larger and high pure water permeability (PWP) with slightly low rection performance compared to that by NIPS. On the contrary, CBzOH membranes prepared with the NIPS method showed three times lower PWP with higher rejection. The chemical resistance of the prepared CBzOH membranes was compared with that of cellulose triacetate (CTA) hollow fiber membrane, which is a typical cellulose derivative as a control membrane, using a 2000 ppm sodium hypochlorite (NaClO) solution. CBzOH membranes prepared with TIPS and NIPS methods showed considerable resistance against the NaClO solution regardless of the membrane structure, porosity and pore size. On the other hand, when the CTA membrane, as the control membrane, was subjected to the NaClO solution, membrane mechanical strength sharply decreased over the exposure time to NaClO. It is interesting that although the CBzOH TIPS membrane showed three times higher pure water permeability than other membranes with slightly lower rejection and considerably higher NaClO resistance, the mechanical strength of this membrane is more than two times higher than other membranes. While CBzOH samples showed no change in chemical structure and contact angle, CTA showed considerable change in chemical structure and a sharp decrease in contact angle after treatment with NaClO. Thus, CBzOH TIPS hollow fiber membrane is noticeably interesting considering membrane performance in terms of filtration performance, mechanical strength and chemical resistance on the cost of slightly losing rejection performance

Abnormalities in perineuronal nets and behavior in mice lacking CSGalNAcT1, a key enzyme in chondroitin sulfate synthesis

Abstract Chondroitin sulfate (CS) is an important glycosaminoglycan and is mainly found in the extracellular matrix as CS proteoglycans. In the brain, CS proteoglycans are highly concentrated in perineuronal nets (PNNs), which surround synapses and modulate their functions. To investigate the importance of CS, we produced and precisely examined mice that were deficient in the CS synthesizing enzyme, CSGalNAcT1 (T1KO). Biochemical analysis of T1KO revealed that loss of this enzyme reduced the amount of CS by approximately 50% in various brain regions. The amount of CS in PNNs was also diminished in T1KO compared to wild-type mice, although the amount of a major CS proteoglycan core protein, aggrecan, was not changed. In T1KO, we observed abnormalities in several behavioral tests, including the open-field test, acoustic startle response, and social preference. These results suggest that T1 is important for plasticity, probably due to regulation of CS-dependent PNNs, and that T1KO is a good model for investigation of PNNs