Bark from trees is considered a worthless raw material. However, this resource could be economically beneficial if utilized efficiently due to its rich chemical compounds. In this study, an ethanol toluene-soluble extractive, alpha-cellulose and lignin obtained from Leucaena leucocephala bark were characterized to determine their chemical functional groups. Based on FTIR spectral analysis, the results indicated that the bands of the functional groups of the extractive from the original bark remain unchanged; however, the absorbance intensity was found to be weaker in the group frequency and fingerprint regions. Removal of extractive, pectin, hemicellulose and lignin from the bark indirectly increased the strong absorbance intensity of cellulose. Broad peaks of OH stretching found in all spectra were assigned to the presence of phenolic OH and aliphatic structures for extractive and aromatic structures of lignin. It was revealed that aromatic functional groups were mainly found in the extractive, while water, carbonyl and ether were the dominant groups in cellulose, and methyl, methylene, carbonyl and carboxyl groups were enriched in lignin. Graphic abstract

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The central composite design of RSM was utilised for the optimization of experimental conditions of microwave-assisted co-pyrolysis of empty fruit bunch (EFB) and waste truck-tire (TT) to maximise the copyrolysis oil and energy yield. The predicted maximum co-pyrolysis oil of 40.0 wt% and energy yield of 59.0% were obtained at the optimum conditions of 505 C pyrolysis temperature, 65.0% of EFB ratio and 60.0 g of activated carbon loading. The reaction temperature and TT ratio in EFB feedstock were identified as the most significant variables that affect the oil and energy yield. A design of experiment was performed to determine the quality of liquid oil. The result indicates the co-pyrolysis oil (PO65) properties were significantly improved after adding TT to EFB biomass. Olefin-rich pyrolytic oil (39.0%) with high selectivity of D-limonene was produced (28.6%). While, the oxygenates and polyaromatics hydrocarbon were reduced to 9.9% and 7.4%, respectively. The energy recovery analysis shows that the optimised copyrolysis oil (PO65) was 20.0% higher as compared to the TT alone. In view of the improved yield and quality of co-pyrolysis oil (PO65), this work shows that co-pyrolysis of EFB/TT presents a viable method to produce diesel-like fuel using the microwave-assisted heating method.

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Two-dimensional assemblies of a series of banana-shaped liquid crystal molecules with short alkyl chains, (LCn, n = 5, 6), are investigated at the solid/liquid interface on graphite surface by using scanning tunneling microscopy (STM) under ambient conditions. The high-resolution STM images of the LCn assemblies demonstrated a lamellae structure with bright bands and dark stripes, in which the alkyl chains of neighboring rows were either interdigitated or tail-to-tail due to the van der Waals interactions. The results in this paper are different with other reported banana-shaped liquid crystals, in which the core may play a dominant role in the self-assembly and the solvent molecules may also play a role in the assemblies. It may be helpful in understanding the assembly mechanism of banana-shaped liquid crystal molecules.

Four novel nonsymmetric dimers containing azobenzene mesogenic groups were synthesized. The nonsymmetric dimers compounds namely, ethyl 4-[(4-{4-(4-((4nitrophenyl)diazenyl)phenoxy)alkyloxy}phenyl)diazenyl]benzoate were obtained from the alkylation of ethyl 4-[(4-(4-bromoalkyloxy)phenyl)diazenyl]benzoate with 4-[(4nitrophenyl)diazenyl]phenol. The mesomorphic properties of the compounds were determined by DSC and polarizing optical microscopy. The first member of the series was nonliquid crystalline while all other homologues display nematic and smectic A phases. The trans-azobenzene groups of the dimers display a high-intensity -* transition at about 365nm and a low-intensity n-* transition at around 465 nm, therefore, photochromism can be achieved by the introduction of the azo linkage to the dimeric liquid crystalline molecules.

The effect of microwave susceptor design on the heating profiles of co-pyrolysis between waste truck tyre and empty fruit bunch was studied. Carbonaceous susceptor was used to elevate the pyrolysis temperature along with increased heating rate. Different design of microwave susceptor and its effect towards the heating profiles of the studied co-pyrolysis process was examined. The aim is to determine the effect of heating rates on the pyrolytic-oil yield, calorific value and energy recovery. From the study, it was revealed that the microwave susceptor design (D1) with a horizontal-layer single-bed, located at the bottom (SB-HL-B) of the feedstocks, showed higher heating rate (83 °C min−1). Higher heating rates were observed to significantly increase pyrolytic-oil (39.0 wt%) and energy yield (59.0%). Such heating rate also upgraded the pyrolytic-oil properties, producing oil with higher calorific value (42.20 MJkg−1). Thus, the present study demonstrated a viable method to optimise pyrolytic-oil yield in producing diesel-like fuel through the adoption of a microwave-assisted heating method.

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