The formulation of optimal mixtures with generalized disjunctive programming: A solvent design case study

Systematic approaches for the design of mixtures, based on a computer‐aided mixture/blend design (CAM^bD) framework, have the potential to deliver better products and processes. In most existing methodologies the number of mixture ingredients is fixed (usually a binary mixture) and the identity of at least one compound is chosen from a given set of candidate molecules. A novel CAM^bD methodology is presented for formulating the general mixture design problem where the number, identity and composition of mixture constituents are optimized simultaneously. To this end, generalized disjunctive programming is integrated into the CAM^bD framework to formulate the discrete choices. This generic methodology is applied to a case study to find an optimal solvent mixture that maximizes the solubility of ibuprofen. The best performance in this case study is obtained with a solvent mixture, showing the benefit of using mixtures instead of pure solvents to attain enhanced behavior. © 2016 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 62: 1616–1633, 2016     

Drilling experiments on a gamma titanium aluminide obtained via electron beam melting

Gamma titanium aluminides are intermetallic structural alloys with many advantages like high temperature and oxidation resistance, low density, high specific strength, rigidity, etc. This makes them promising candidates for critical applications where both mechanical and thermal properties are required. Unfortunately, their machinability is demanding, generating low cutting life and poor surface conditions. A deeper knowledge on the machining parameters is essential for a wider application of these heat-resistant light-weight alloys in aircraft and automotive industry. In this paper, the performance of uncoated carbide drills in drilling a gamma titanium aluminide was analysed. The workpiece material was obtained via electron beam melting (EBM) process, a versatile technology for additive manufacturing of complex metal parts from metal powders. EBM is highly appealing in the field of aeroengine components, and it is particularly interesting in processing gamma titanium aluminides. Cutting performances were measured in terms of tool wear, surface roughness, dimensional and geometric errors. The experimental results show strong dependence of tool wear and part quality on cutting parameters, with poor tool life compared with other work materials.     

Screening tests for the evaluation of nanoparticle titania photocatalysts

BACKGROUND: Nano‐sized titanium dioxide has potential as a photocatalyst, and doped variants may have different photocatalytic properties. Nano‐titanias with a wide range of dopants and compositions can be prepared using continuous hydrothermal flow synthesis (CHFS), but when many samples are made, a large‐scale screening test is required to investigate their properties. A range of doped nano‐titanias were prepared using a CHFS route, and investigated as powders using a range of photocatalytic test methods. These tests included decolourization of methylene blue (in the presence of oxygen), partial oxidation of a simple alcohol (propan‐2‐ol) and the degradation of aqueous solutions of dichloroacetic acid. The practicality of the tests for large‐scale screening was considered, and the test results were cross‐correlated to see if any of them gave similar ranking for activity of the photocatalysts. RESULTS: Two of the tests, namely DCA degradation and propan‐2‐ol, gave similar rank ordering for the nanopowders, while the MB decolourization results did not suggest a strong correlation with any other test. The addition of metal dopants was observed to produce varying results between different dopants and tests. CONCLUSIONS: Two of the tests, DCA degradation and MB decolourization in visible light, were recommended for further use as screening tests. Copyright © 2009 Society of Chemical Industry