Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol, ethanol and isopropanol as solvent and hydrogen donor. Characterisation of the bio-oil and the upgraded bio-oils was carried out including moisture content, elemental content, pH, heating value, gas chromatography-mass spectrometry (GCMS), Fourier transform infrared radiation, ¹³C nuclear magnetic resonance spectroscopy, and thermogravimetric analysis to evaluate the effects of blending and supercritical reactions. The GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol reaction. The ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH value. Simply blending crude bio-oil with isopropanol was effective in increasing the C and H content, reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg^‒1 in the crude bio-oil. After the supercritical isopropanol reaction, the heating value of the liquid product slightly further increased to 28.85 MJ·kg^‒1.     

Characterisation of proteolytic enzymes from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii)

BACKGROUND: Fresh water prawn in Thailand is widely consumed due to its delicacy. During postmortem handling and storage, prawn meat becomes soft and mushy, probably as a result of indigenous proteases. Therefore, an understanding of prawn proteases associated with the degradation of muscle proteins from fresh water prawn could pave the way for prevention of such a phenomenon during extended storage. RESULTS: Proteolytic enzymes in the crude extract (CE) from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) were characterised. CE from muscle exhibited the highest hydrolytic activities towards haemoglobin at pH 5 and 50 °C, while that from hepatopancreas had the highest activity on casein at pH 7 and 60 °C. Based on inhibitor study, cysteine protease and serine protease were dominant in CE from muscle and hepatopancreas, respectively. CE from muscle rarely hydrolysed natural actomyosin (NAM), but could not degrade pepsin‐soluble collagen (PSC). Conversely, NAM and PSC were susceptible to hydrolysis by CE from hepatopancreas as evidenced by the marked decreases in band intensity. Activity staining using haemoglobin, casein and gelatin as substrates revealed that no proteolytic or gelatinolytic activity was observed in CE from prawn muscle, while CE from hepatopancreas exhibited pronounced hydrolytic activities towards all substrates. CE from muscle showed calpain and cathepsin L activities but CE from hepatopancreas mainly exhibited tryptic and chymotryptic activities. CONCLUSION: Serine proteases, mainly trypsin‐like or chymotrypsin‐like, from hepatopancreas were probably responsible for the softening of prawn meat during postmortem storage via the degradation of both muscle and connective tissues. Copyright © 2010 Society of Chemical Industry     

Soluble dietary fibres from sugarcane bagasse

Soluble dietary fibres from sugarcane bagasse were extracted under alkaline conditions and characterised. Precipitated fibres were dialysed, and the fibre composition was evaluated before and after the dialysis step. Compositional analysis indicated that the fibres both before and after dialysis consisted of 39% w/w total sugars, 16% w/w protein, 10% w/w Klason lignin and 30% w/w ash. Xylose was the main neutral sugar followed by arabinose with glucose, galactose and uronic acids also present in all samples. The structural properties were also spectroscopically examined, which confirmed the presence of arabinoxylans. Macromolecular characterisation revealed that molecular weight is reduced after dialysis, indicating that a range of dietary fibres with different macromolecular characteristics may be obtained depending on the specific processing steps. The present work shows that soluble arabinoxylans may be obtained from sugarcane agricultural wastes that may be used as a source of novel dietary fibres.     

Extraction and characterisation of pectin polysaccharide from soybean dreg and its dispersion stability in acidified milk drink

In this study, pectin polysaccharide (SDPP) was obtained from soybean dreg (26.2% yield), and characteristics of SDPP were compared with those of soybean soluble polysaccharides (SSPS) and citrus pectin (HMP). The galacturonic acid and molecular weight of SSPS, SDPP or HMP were 11.8%, 40.6% or 70.2% and 112, 446, or 440 kDa. SDPP had similar viscosity and protein content to SSPS, and functional groups and linear structure to HMP. SSPS, SDPP or HMP differed in particle size of 260, 467 or 1195 nm and ζ–potential of −5.8, −14.6 or −23.5 mV at pH 4.0. The precipitation of acidified milk drink (AMD) was 6.31% without stabiliser or below 1.75% with 0.4% SDPP at pH 3.6–4.6. These results suggested that SDPP combines the structure and characteristic of HMP and SSPS, and AMD with SDPP had great stabilising behaviour at wider pH range (pH 3.6–4.6).     

Characterisation of a novel laminarinase from Microbulbifer sp. ALW1 and the antioxidant activity of its hydrolysates

Laminarin and its derived oligosaccharides have diverse bioactivities. The β-1,3-glucanase in marine bacteria can be employed as a tool to digest laminarin in the cell wall of brown algae. Here, we cloned, expressed and characterised a β-1,3-glucanase (laminarinase), MaLamNA, from the previously characterised marine bacterium Microbulbifer sp. ALW1, phylogenetically distinct from the glycoside hydrolase families of characterised laminarinases. The recombinant laminarinase was heterologously expressed and purified from Pichia pastoris GS115 cells with a molecular mass of 57.3 kDa. MaLamNA exerted its hydrolytic activity specifically against laminarin, with the highest activity at 45 °C and pH 4.5–5.5, respectively, and demonstrated high stability against extreme acidic and alkaline pH exposure. The addition of reducing agent dithiothreitol could significantly enhance the activity of MaLamNA. The hydrolytic products of laminarin by MaLamNA exhibited more effective antioxidant activities than the undigested laminarin. These characteristics of MaLamNA provide clues to its industrial application for laminarin bioresource development.     

Towards sensible toxicity testing for nanomaterials: proposal for the specification of test design

During the last decade, nanomaterials (NM) were extensively tested for potential harmful effects towards humans and environmental organisms. However, a sound hazard assessment was so far hampered by uncertainties and a low comparability of test results. The reason for the low comparability is a high variation in the (1) type of NM tested with regard to raw material, size and shape and (2) procedures before and during the toxicity testing. This calls for tailored, nanomaterial-specific protocols. Here, a structured approach is proposed, intended to lead to test protocols not only tailored to specific types of nanomaterials, but also to respective test system for toxicity testing. There are existing standards on single procedures involving nanomaterials, however, not all relevant procedures are covered by standards. Hence, our approach offers a detailed way of weighting several plausible alternatives for e.g. sample preparation, in order to decide on the procedure most meaningful for a specific nanomaterial and toxicity test. A framework of several decision trees (DT) and flow charts to support testing of NM is proposed as a basis for further refinement and in-depth elaboration. DT and flow charts were drafted for (1) general procedure—physicochemical characterisation, (2) choice of test media, (3) decision on test scenario and application of NM to liquid media, (4) application of NM to the gas phase, (5) application of NM to soil and sediments, (6) dose metrics, (S1) definition of a nanomaterial, and (S2) dissolution. The applicability of the proposed approach was surveyed by using experimental data retrieved from studies on nanoscale CuO. This survey demonstrated the DT and flow charts to be a convenient tool to systematically decide upon test procedures and processes, and hence pose an important step towards harmonisation of NM testing.     

Acoustic emission source characterisation using evolutionary optimisation

When a crack initiates and grows in a metal or composite structure, for example, due to high cycle fatigue, the crack propagation gives rise to acoustic emissions (AE)—ultrasonic waves travelling through the structure. Because the presence and rate of growth of any cracks are important pieces of information about the condition or health of the structure, the monitoring of AE activity using sensors mounted on its surface is a potentially useful technique of structural health monitoring. In tests, acoustic emissions are often simulated by breaking a pencil lead against the surface of the structure in a standardised way (a "Hsu‐Nielsen" source), but the forces that this imparts are not well understood at present. The current paper proposes a new evolutionary optimisation‐based approach to source characterisation. The principle is to introduce a parametrised representation of a general source and then identify the parameters that allow the source to best match responses measured elsewhere on the structure. The predicted responses are modelled using a local interaction simulation approach (LISA) algorithm to simulate the propagation of the ultrasonic waves. The approach is validated here using experiments on AE propagation in thin plate‐like structures, where the ultrasound propagates as Lamb waves. Three separate case studies are proposed here. In the first case, an idealised point source is simulated using laser‐generated ultrasound, and the optimisation algorithm uses a two‐dimensional LISA model. A differential evolution optimisation scheme is used to find the optimal profile of forcing to match the simulation with experiment. In the second case, the two‐dimensional LISA approach is used to characterise the forces associated with standard pencil lead breaks. The final study addresses the full three‐dimensional wave propagation. Because of the computational expense of the latter calculation, the LISA algorithm is implemented using a CUDA graphics card computer system.     

An investigation on oxidation/carburisation of 9Cr-1Mo steel heat exchanger tube in an AGR environment

Abstract

9Cr–1Mo steels have been used extensively in the power generation industry. In this study, a wide range of experimental samples exposed at different times and temperatures in a CO₂ environment were analysed to look at the development of the metal and oxides over time. The main objective of this work was to obtain a better understanding of the carburisation and oxidation behaviour of 9Cr 1Mo steels as a function of temperature/time, with special attention paid to the transition from protective to breakaway oxidation. In addition, experiments were also carried out to investigate any links between oxidation transition and carburisation behaviour of these materials.     

The incremental Virtual Fields Method and prestretching method applied to rubbers under uniaxial medium‐strain‐rate loading

Conventional dynamic experiments on rubbers have several limitations including low signal‐to‐noise ratio and a long time period during which the specimen is not in static equilibrium, which causes difficulties separating constitutive material behaviour from specimen response. In order to overcome these limitations, we build on previous research in which the Virtual Fields Method (VFM) is applied to dynamic tensile experiments. A previous study has demonstrated that the VFM can be used to identify the material parameters of a hyperelastic model for a given rubber based on optical measurements of wave propagation in the rubber, eliminating the need for force measurements by instead using acceleration fields as a “virtual load cell.” In order for us to successfully characterise the strain hardening in the material, large deformations are required, and these were achieved by applying static preloads to the specimen before the dynamic loading. In order for us to then apply the VFM, measurements of the static force, or strain, or both, are required. This paper explores different methods for applying the VFM, in particular, comparing the use of a static force measurement, as in the previous research, to methods that only require strain fields in order to apply the incremental equation of motion. Finite element method simulations were conducted to compare the identification sensitivity to experimental error sources between the 2 VFM implementations; the experimental data used in the previous studies were then applied to the incremental VFM. A further experimental comparison is provided between constitutive parameters obtained in tensile experiments using the VFM and compressive measurements from a modified split Hopkinson bar technique equipped with a piezoelectric force transducer. Finally, there is a discussion of the effects of preloading and relaxation in the material.     

Process optimisation and microstructural evolution of friction stir spot-welded Al6061 joints

The joint strength and subsequent microstructural evolution of a friction stir spot-welded AA6061-T6 alloy was investigated according to the process parameters: tool rotation speed, dwell time and pin angle of the tool. A maximum tensile shear load of 2.78?kN was obtained from the joints generated under a combination of process variables like 1000 and 1500?rev?min^?1, 5?s, 5°. Under a fixed pin angle of 5° and a rotational speed of 1000?rev?min^?1, an increase in dwell time from 1 to 5?s resulted in a considerable increase in tensile shear load. An empirical process map under a fixed tool design is proposed to determine a feasible range of process conditions.