On sufficient conditions for multi-field generalised Proca theories

We derive sufficient conditions for theories consisting of multiple vector fields, which could also couple to external fields, to be multi-field generalised Proca theories. We derive the conditions by demanding that the theories have the required structure of constraints, giving the correct number of degrees of freedom. The Faddeev-Jackiw constraint analysis is used and is cross-checked by Lagrangian constraint analysis. To ensure the theory is constraint, we impose a special case of Hessian condition where time-time and time-space components of the Hessian matrix vanishes. The derivation is benefitted from the realisation that the theories are diffeomorphism invariance (or, in the case of flat spacetime, invariant under Lorentz isometry). The sufficient conditions obtained include a refinement of secondary-constraint enforcing relations derived previously in literature, as well as a condition which ensures that the iteration process of constraint analysis terminates. Some examples of theories satisfying, or not satisfying, the sufficient conditions are provided. Most notably, due to the obtained refinement on some of the conditions, some theories which are previously interpreted as being undesirable are in fact legitimate, and vice versa.Comment: 29 pages, no figur

An overview of Engineering Aspects of Solid State Fermentation

Solid substrate cultivation (SSC) or solid state fermentation (SSF) is envisioned as a prominent bio conversion technique to transform natural raw materials into a wide variety of chemical as well as bio-chemical products. This process involves the fermentation of solid substrate medium with microorganism in the absence of free flowing water. Recent developments and concerted focus on SSF enabled it to evolve as a potential bio- technology as an alternative to thetraditional chemical synthesis. SSF is being successfully exploited for food production, fuels, enzymes, antibiotics, animal feeds and also for dye degradation. This paper discusses the various micro and macro level engineering problems associated with SSF and some possible solutions for its full commercial realization

Synthesis and characterization of carbon-based catalyst derived from seaweed

This study reports the synthesis and characterization of carbon-based catalyst derived from local seaweed species, Sargassum Polycystum. The synthesis involved pyrolysis at 400°C for 4h followed by sulfonation. The characterization study showed that the material had a total acidity of 2.01 mmol/g, and thermally stability up to 240°C. FT-IR analysis detected the presence of -COOH, -OH and -SO3H functional groups. From the EDS analysis, the concentration of SO3H was calculated as 0.28 mmol/g. Metal were also detected in the sample with the order of concentration as Pb>Mg>Fe>Cd>Cu with a range of 0.055-0.110 ppm. The SEM analysis showed the sample as porous material. In conclusion, the functionalized carbon material had a great potential as a catalyst for many reactions such as biodiesel production

Synthesis and characterization of supported sugar catalyst by dip coating method

Sugar catalyst is a novel solid acid catalyst with reactivity comparable to that of sulphuric acid in biodiesel production. However, the fine powder form of sugar catalyst with the non-porous structure might cause large pressure drop in a packed bed reactor due to low bed porosity, affecting the reaction conversion especially in gas phase reaction. Furthermore, higher pressure drop requires higher electrical energy to drive the fluid through. Increasing the particle size is anticipated to be able to overcome the pressure drop matter. Hence, a deposition of sugar catalyst on larger particle materials was studied. Three types of materials were used for this investigation namely aluminum, silica and clay. The deposition was done via dip-coating method. The materials were characterized for their total acidity, thermal stability, functional groups, surface area, and element composition. The total acidity for SCDCAl, SCDCSi, and SCDCCl were 0.9 mmol/g, 0.2 mmol/g, and 0.4 mmol/g, respectively. The ratio of char deposited on SCDCAl, SCDCSi and SCDCCl were 0.9 g of support/g of carbon, 0.040 g of support/g of carbon, and 0.014 g of support/g of carbon respectively. FTIR and EDX analyses were carried out to determine the presence of active sites of the catalysis by identifying the functional groups such as –COOH, -OH, -SO3H. The results showed that –SO3H was detected on the surface of synthesized catalysts, except for SCDCC1.The pore size of SCDCAl, SCDCSi and SCDCCl were classified as macropores because the average diameter were greater than 50nm.. The catalysts were stable up to 400 °C. The results showed that the dip- coating method could deposit sugar catalyst on aluminum, silica, and clay at low total acidity concentration

Removal of Malachite Green from Aqueous Solution by waste tyre derived activated carbon

Waste rubber tyres were used to prepare activated carbon via destructive distillation method employing a two stage process i.e. carbonization and chemical activation in a tubular furnace. Carbonization was done at 500°C for 1 h followed by impregnation of char with NaOH. Activation was done in a horizontal tube furnace via CO2 activation. Two variables and three parameters i.e. impregnation ratio between NaOH and char (1:1 and 3:1), activation temperature (700°C and 900°C), and activation time (60 min and 180 min) were studied and its effects on percentage yield, and malachite green (MG) dye removal were compared and presented in this paper. IR spectra of all samples a number of bands at 1710, 1620, and 1054 cm–1 –1026 cm–1 which proved the presence of carboxylic, carbonyl, and some acids, alcohols, ether and ester groups on the surface of carbon prepared. Activated carbon, AC6, which was prepared at ratio 3:1 and heated at 900°C for 60 min preparation was selected due to high surface area (313.17 m2/g) and removed about 97.43% of MG dye after 60 minutes. AC6 was best fitted to the Freundlich isotherm indicating multilayer adsorption while the adsorption kinetic followed pseudosecond order kinetics. The maximum monolayer adsorption was 128.21 mg/g

Preparation and Characterization of Sugar Based Catalyst on Various Supports

A novel structured carbon-based acid catalyst was prepared by depositing the carbon precursor onto glass, ceramic and aluminum supports via dip-coating method, followed by carbonization process for converting the d-glucose layer into black carbon char in an inert nitrogen environment at 400 °C. Then, the –SO3H group was introduced into the framework of the carbon char by multiple vapor phase sulfonation. Four different carbonization methods were carried out (dry pyrolysis and hydrothermal carbonization with or without pressurized) in the catalyst preparation while among the carbonization methods, the samples which prepared from dry pyrolysis without pressurized process showed the strong acidity due to highest adsorption of acid group in the catalyst surface although the catalyst attached onto the support was the least compared to other preparation methods. Among the catalysts, the sulfonated carbon-base catalyst that is attached on the ceramic support exhibited the highest aci-dity (1.327 mmol/g) followed by the catalyst deposited on the glass (0.917 mmol/g) and aluminum (0.321 mmol/g) supports. The porous structure of ceramic surface, allowed a better interaction between reactants and –SO3H site in the carbon. Through the FT-IR analysis, it was observed that the functional groups –COOH, –OH, and –SO3H were present in the active sites of the catalysts. The surface areas of  glass (Si–SC), ceramic (Ce–SC) and aluminum (Al–SC) catalysts were larger than 1 m2/g, whereas the pore size belongs to macroporous as the average pore size is more than 50 nm. It is also stable within the temperature of 400 °C as there was less than 10% weight loss revealed from the TGA analysis.

Composting paper and grass clippings with anaerobically treated palm oil mill effluent

Purpose The purpose of this study is to investigate the composting performance of anaerobically treated palm oil mill effluent (AnPOME) mixed with paper and grass clippings. Methods Composting was conducted using a laboratory scale system for 40 days. Several parameters were determined: temperature, mass reduction, pH, electrical conductivity, colour, zeta potential, phytotoxicity and final compost nutrients. Results The moisture content and compost mass were reduced by 24 and 18 %, respectively. Both final compost pH value and electrical conductivity were found to increase in value. Colour (measured as PtCo) was not suitable as a maturity indicator. The negative zeta potential values decreased from −12.25 to −21.80 mV. The phytotoxicity of the compost mixture was found to decrease in value during the process and the final nutrient value of the compost indicates its suitability as a soil conditioner. Conclusions From this study, we conclude that the addition of paper and grass clippings can be a potential substrate to be composted with anaerobically treated palm oil mill effluent (AnPOME). The final compost produced is suitable for soil conditioner

Computational fluid dynamics analysis of flat-plate and v-grooved solar heat collector of different materials for plastic waste drying

Plastic waste pollution has become one of the most critical environmental issues in the recent years as it adversely affects the ecosystem in many ways. River has been reported for playing an important role in transporting plastic waste into the environment and continued efforts have been done to prevent, control, and treating plastic waste intending to support river conservation. In this present work, computational fluid dynamics (CFD) analysis was conducted to study the performance of solar heat collector (SHC) as a baseline study for the application of plastic drying at the post-treatment stage for recycling and upcycling of plastic waste. SHCs incorporated with different absorber configuration (flat and V-grooved) and absorber material (aluminum and copper) were tested in the aspect of heat transfer and fluid flow characteristics to identify the enhancement mechanism occurs in the collector. The findings indicate that SHC with V-grooved copper absorber exhibits highest collector efficiency (44.95%). However, the application of aluminum absorber would be sufficient for the case where low velocity drying process is performed