Automated targeting approach for synthesis of heat exchanger network (HEN) with trigeneration system

AbstractIn this work, a novel systematic approach for the synthesis of heat exchanger network (HEN) with trigeneration system via multiple cascades automated targeting (MCAT) is presented. The optimisation objective is to locate the minimum total operating cost (TOC) of the system. The minimum hot and cold utilities of the HEN, allocation of utilities and potential power generation as well as the type of fuel can be determined via proposed approach. A case study of formic acid processing plant is solved to illustrate proposed approach

Bacterial Metabolism During Biofilm Growth Investigated by 13C Tracing

This study investigated the metabolism of Pseudomonas aeruginosa PAO1 during its biofilm development via microscopy imaging, gene expression analysis, and 13C-labeling. First, dynamic labeling was employed to investigate glucose utilization rate in fresh biofilms (thickness 40∼60 micrometer). The labeling turnover time of glucose-6-P indicated biofilm metabolism was substantially slower than planktonic cells. Second, PAO1 was cultured in continuous tubular biofilm reactors or shake flasks. Then 13C-metabolic flux analysis of PAO1 was performed based on the isotopomer patterns of proteinogenic amino acids. The results showed that PAO1 biofilm cells during growth conserved the flux features as their planktonic mode. (1) Glucose could be degraded by two cyclic routes (the TCA cycle and the Entner-Doudoroff-Embden-Meyerhof-Parnas loop) that facilitated NAD(P)H supplies. (2) Anaplerotic pathways (including pyruvate shunt) increased flux plasticity. (3) Biofilm growth phenotype did not require significant intracellular flux rewiring (variations between biofilm and planktonic flux network, normalized by glucose uptake rate as 100%, were less than 20%). (4) Transcription analysis indicated that key catabolic genes in fresh biofilm cells had expression levels comparable to planktonic cells. Finally, PAO1, Shewanella oneidensis (as the comparing group), and their c-di-GMP transconjugants (with different biofilm formation capabilities) were 13C-labeled under biofilm reactors or planktonic conditions. Analysis of amino acid labeling variances from different cultures indicated Shewanella flux network was more flexibly changed than PAO1 during its biofilm formation

DDX3X loss is an adverse prognostic marker in diffuse large B-cell lymphoma and is associated with chemoresistance in aggressive non-Hodgkin lymphoma subtypes.

Funder: addenbrooke's charitable trust, cambridge university hospital

Battery operated portable fridge

This report is a continuation of previous Final Year Project on Battery Operated Fridge. In this project, electrical circuit design with temperature control will be investigated in order to save the energy consumption so that it can be truly energy saving battery operated. The main improvement that is made is that an additional circuit is installed to detect the temperature and save the energy consumption to prolong the life of the batteries. Other improvements are made on the exterior design so that it will make the portable fridge lighter in weight and more convenience for the user.Bachelor of Engineerin

Bacterial synthesis of nanocatalyst and biofilm-templated nanocatalytic system for water purification

Microorganisms have the potential to change the oxidation state of metals and these microbial processes have opened up a new window for novel applications including biosynthesis of metal nanomaterials. Planktonic cells based synthesis of metal nanomaterials has been studied previously; however, much of the mechanistic details are still relatively unknown. The application of planktonic cells-based metal nanomaterials synthesis is constrained to batch and fed-batch processes. Moreover, planktonic cells have low tolerance to toxic substrates or products which undermine the synthesis efficiency of metal nanomaterials. Microbial biofilms might offer a solution. Biofilms are structured, surface-associated, microbial communities that are prevalent in most natural environments, engineering systems and clinical settings. One of the most important features of a biofilm is the presence of extracellular polymeric substances (EPS) that form a matrix and encase the cells in the biofilm. Cells in biofilms often form structurally stable communities and show a remarkable resistance against various biocides. Hence, we hypothesize that biofilm may be a good candidate to use for the synthesis of metal nanomaterials. This project aims to develop a robust and efficient biofilm-based nano-catalytic system which is applicable to water purification and environmental remediation. To understand the mechanism of nanomaterial production by microorganism, we used model organism Shewanella oneidensis MR-1 to synthesize silver, silver sulfide and palladium nanoparticles. We showed that the synthesized metal and metalloid nanoparticles exhibit catalytic activity. Microbial synthesis of silver and silver sulfide is influenced by outer membrane cytochromes, while synthesis of palladium nanoparticles (NPs) is influenced by periplasmic [NiFe]-hydrogenase. In addition, we also revealed that in extracellular biosynthesis of NPs, the usually neglected non-cell-associated NPs could have high catalytic activity, highlighting the need of novel methods that can efficiently retain extracellular NPs in the biosynthesis processes. The second part of the project focused on exploring the reductive formation of Pd(0) nanoparticles in biofilms under ambient conditions, understanding the metabolic responses of the biofilms during the process of palladium nanoparticles synthesis, and developing a robust nanocatalytic biofilm through genetic engineering. We showed that the S. oneidensis biofilms can reduce Pd(II) and accumulate Pd(0) nanocrystals with a size of 10-20 nm in the biofilm matrix and in the cell membrane even under bulk aerobic conditions, and that the S. oneidensis biofilms with Pd(0) nanocrystals exhibit nanocatalytic activity. However, we also observed that Pd(II) exposure inhibits cellular respiration and energy metabolism of S. oneidensis cells, posing a risk of biofilm detachment. To improve the robustness of biofilm-based nanocatalyst, we explored two approaches: (1) genetic manipulation via c-di-GMP pathway and (2) physical alteration via controlled pyrolysis. In previous studies, c-di-GMP has been reported to be able to influence the production of EPS and influence biofilm processes such as cell dispersal. In our study, we showed that we can increase the production of EPS and alleviate the biofilm detachment during the biofilm’s exposure to Pd(II). The insertion of plasmid pYedQ2 can increase the production of cytoplasmic c-di-GMP, an upstream signalling molecule which influences several key cellular processes, such as cellular motility, extracellular electron transport, iron uptake and biofilm formation in S. oneidensis MR-1. Further, we also showed that controlled pyrolysis leads to carbonisation of biofilm and formation of stable, abiotic heteroatom (N and P)-doped carbon-palladium (C-Pd) nanocomposite catalyst. Moreover, the pyrolysed biofilm-templated C-Pd nanocomposite catalyst show high Cr(VI) reduction, and maintained high reduction rate even on the 5th catalytic cycle. Although the pyrolysed heteroatom-doped carbon on its own has no Cr(VI) reduction activity, it seems to enhance the catalytic activity of the Pd nanocrystals in the C-Pd nanocomposite.Doctor of Philosophy (IGS

Stock prices synchronicity in both emerging and developed countries.

Stock price movements are more synchronous in poor economies than in rich economies. We propose that a well developed stock market promote informed arbitrage, which capitalized firm-specific information

Music piracy among Singapore undergraduates.

This project looked into the attitudes of local undergraduates towards music piracy as well as their level of participation. Another objective was to explore into possible solutions for the music industry and local authorities to reduce such activities in Singapore

Development of A Smart Autonomous Lawnmover

This study aims to improve the lawn mowing quality by develop a smart lawnmower through literature reviews. The smart lawnmower intends to solve mainly the limitations of existing smart lawnmowers and the research gaps in literature review. The main purpose of this study is to benefit society by advancing innovation and improving quality of life

A TRIZ-Integrated Conceptual Design Process of a Smart Lawnmower for Uneven Grassland

Existing smart lawnmowers, while convenient to use, have significant limitations, such as a lack of manoeuvrability on uneven agricultural grassland (constraint 1), high charging frequency (constraint 2) and low local market penetration (constraint 3). Although the effectiveness of the theory of inventive problem solving (TRIZ) has been demonstrated in several design studies, there also seems to be a lack of research addressing the design difficulties of smart lawnmowers using this method. With the use of the TRIZ method, this study seeks to conceptually design a smart lawnmower for uneven grassland. Tools from TRIZ were used, including cause-effect chain analysis, technical contradictions, physical contradictions, and substance field modelling. In developing a design concept, constraints were solved by inventive principles, separation strategies and standard inventive solutions. For constraint 1, the following solutions were chosen with the appropriate principles: using larger wheels (#17, another dimension: using a second or third dimension), a pivot design (#30, flexible shell: replacing rigidity with flexibility and movability) and replacing the motor with one that has more power or torque. For constraint 2, the following solutions were chosen: to reduce weight, add holes in the mower housing (#31, porous materials: making an object porous or adding porous elements) and attach a solar panel to recharge batteries with solar energy (#28, mechanical substitution: using electric, magnetic or other fields to interact with object). Using other materials or technologies to minimise costs (#13, the other way around: using the opposite way) and a modular design concept to reduce maintenance costs (#1, segmentation: dividing an object into independent parts) were the chosen ways to solve constraint 3. Conceptualisation and design analysis were also performed. Although the effectiveness of the concept is unclear, these suggestions are supported by previous research and could potentially solve some of the problems with smart lawnmowers