Optimizing nozzle convergent angle using central composite design on the particle velocity and acoustic power level for single-hose dry ice blasting nozzle

Journal of Thermal Analysis and Calorimetry - One of the important parameters in developing dry ice blasting nozzle is the high-speed dry ice pellets. However, many studies focus primarily only on...     

Molecular imprinted polymer for β-carotene for application in palm oil mill effluent treatment

Palm oil mill effluent (POME) is one of the most significant pollutant in the form of wastewater. It could have negative effects on the environment include the emission of biogas and water pollution which comes from discharging the brownish tick POME to the water bodies if not properly managed. Discharge of dark brownish colored of POME directly into water bodies may affect the aquatic life as it will reduce sunlight penetration and suppress the photosynthetic activity. A molecularly imprinted polymer (MIP) for removal of β-carotene from POME has been aimed to develope in this study. The preparation of β-carotene imprinted and non-imprinted polymer (NIP) involves polymerization of β-carotene (or without it) with β-cyclodextrin (β-CD), 9-vinylcarbazole (9VC), tolylene diisocyanate (TDI) and N,N-dimethylformamide (DMF) as the monomer, co-monomer, cross-linker and solvent (porogen), respectively. Analysis from FTIR showed that MIP and NIP have similar characteristic peak with different peaks intensity, indicating the similarity in the backbone structure of polymerization. TGA result displayed high thermal stability with final decomposition at 320 °C for MIP-β-CD-9VC as compared to NIP-β-CD-9VC. The pH study shows that sorption of β-carotene increased with decreasing the pH of POME and the maximum sorption capacities achieved at pH 2 were 10 μg/g and 7 μg/g for MIP-β-CD-9VC and NIP-β-CD-9VC, respectively. The maximum sorption achieved by using 500 mg of MIP as the sorption of β-carotene increased with increasing the dosage of MIP. Kinetic model evaluation has been applied on this prepared materials. The sorption equilibrium data was well described by Freundlich model. The results indicated that the sorption of β-carotene on MIP follows a pseudo–second–order kinetic.     

Acetyl- and O-alkyl- derivatives of β-mangostin from Garcinia mangostana and their anti-inflammatory activities

Pure β-mangostin (1) was isolated from the stem bark of Garcinia mangostana L. One monoacetate (2) and five O-alkylated β-mangostin derivatives (3–7) were synthesised from β-mangostin. The structures of these compounds were elucidated and determined using spectroscopic techniques such as 1D NMR and MS. The cytotoxicities and anti-inflammatory activities of these five compounds against RAW cell 264.7 were tested. The structural-activity relationship studies indicated that β-mangostin showed a significant activity against the LPS-induced RAW cell 264.7, while the acetyl- as well as the O-alkyl- β-mangostin derivatives did not give good activity. Naturally occurring β-mangostin demonstrated comparatively better anti-inflammatory activity than its synthetic counterparts.     

Isolation and structural modifications of ananixanthone from Calophyllum teysmannii and their cytotoxic activities

Two naturally occurring xanthones, ananixanthone (1) and β-mangostin (2), were isolated using column chromatographic method from the n-hexane and methanol extracts of Calophyllum teysmannii, respectively. The major constituent, ananixanthone (1), was subjected to structural modifications via acetylation, methylation and benzylation yielding four new xanthone derivatives, ananixanthone monoacetate (3), ananixanthone diacetate (4), 5-methoxyananixanthone (5) and 5-O-benzylananixanthone (6). Compound 1 together with its four new derivatives were subjected to MTT assay against three cancer cell lines; SNU-1, K562 and LS174T. The results indicated that the parent compound has greater cytotoxicity capabilities against SNU-1 and K562 cell lines with IC₅₀ values of 8.97 ± 0.11 and 2.96 ± 0.06 μg/mL, respectively. Compound 5 on the other hand exhibited better cytotoxicity against LS174T cell line with an IC₅₀ value of 5.76 ± 1.07 μg/mL.     

Cellulose nanocrystals from bleached rice straw pulp: acidic deep eutectic solvent versus sulphuric acid hydrolyses

The present work aims to investigate the feasibility of oxalic acid-choline chloride deep eutectic solvent (OA-ChCl DES), which serves as a promising green solvent that utilized in the acidic deep eutectic solvent (DES) hydrolysis. Oxalic acid-choline chloride DES cellulose nanocrystal (OA-ChCl DES CNC) was isolated from the bleached DES treated pulp (BP) through the acidic DES hydrolysis using 1:1 molar ratio of OA-ChCl DES. The functional groups, crystallinity index, morphological structure, particle size, zeta potential, thermal stability and surface chemistry of the OA-ChCl DES CNC were compared with the sulphuric acid cellulose nanocrystal (SA-CNC) that prepared via sulphuric acid hydrolysis. The findings revealed the presence of negatively charged carboxyl groups on OA-ChCl DES CNC surface after the acidic DES hydrolysis. The physicochemical analyses verified that the OA-ChCl DES CNC was in nano-sized range with polydispersity index (PdI) of 0.56, indicating slightly monodispersed nanoparticles. A stable OA-ChCl DES CNC colloidal suspension with zeta potential value of ?52.1?±?5.2 mV was obtained. The OA-ChCl DES CNC outweighed the SA-CNC in term of thermal stability (288 °C) despite having a slightly lower crystallinity index (76.7%). In fact, the OA-ChCl DES CNC with a yield of 55.1% was achieved through the acidic DES hydrolysis, suggesting that the OA-ChCl DES was capable of promoting efficient cleavage of strong hydrogen bonds in BP.

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Improved Performance of W／HZSM-5 Catalysts for Dehydroaromatization of Methane

The dehydroaramatization of methane over W-supported ZSM-5 with varying degrees of Li^ ion-exchanged catalysts was studied with and without oxygen at 1073 K and atmospheric pressure.Catalyst activity and stability were found to be influenced by the catalyst acidity related to BrSnsted acid sites and by the presence of oxygen in the feed. The NH3-TPD and FTIR-pyridine results demonstrated that partially exchanged of H^ ions by Li^ into the W/HZSM-5 catalysts could be used to control the amount of strong acid sites on the catalyst surface. Without oxygen, the 3WHLi-Z (5:1) catalyst that has strong acid sites equal to nearly 74% of the original strong acid sites in the parent HZSM-5 exhibited the highest methane conversion and selectivity towards aromatics. However, the catalyst deactivated in a five hour period. In the presence of oxygen, the catalyst activity and stability could be improved further.The results of this study revealed that a suitable amount of strong Bronsted acid sites as well as oxygen addition in the feed increased the catalyst activity and stability. The 3WHLi-Z(5:1) catalyst exhibited improved performance in the dehydroaromatization of methane.     

Environmental assessment of coastal sediments by the elemental ratioing technique

The distribution of heavy and trace elements in coastal sediments was obtained by elemental analysis techniques such as INAA and GFAAS. The elemental concentrations were expressed in terms of enrichment factors derived by the elemental ratioing method, and evaluation was done by comparison to those found in SRMs. The associated sources of polluting elements were traced from their distribution patterns and, where applicable, related to the surrounding activities. Sample to sample variation was also taken into account to establish any correlative factors.