Siwaporn Meejoo Smith

Transesterification of soybean oil using bovine bone waste as new catalyst.

Calcined bovine bone waste was employed to catalyze the transesterification reaction between soybean oil and methanol. The influence of various conditions on the efficiency of the transesterification was studied i.e. type of reactor, temperature, catalyst loading and methanol/oil ratio. The optimum yield of methyl ester (97%) was obtained by performing the closed-system transesterification at 65 °C for 3 h with catalyst loading of 8% wt and 6:1 methanol to oil ratio, using bone calcined at 750 °C. Calcination of the commercial bovine bone at 650 °C and above results in conversion of the calcium carbonate component to calcium oxide, with the major component being crystalline hydroxyapetite. Calcium oxide is believed to be responsible for the catalytic activity of the material. The reusability, low cost and low catalyst loading required (4% wt) may make bovine bone an attractive alternative to existing transesterification catalyst systems.

Chemical and structural investigation of lipid nanoparticles: drug–lipid interaction and molecular distribution

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of gamma-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the gamma-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ((1)H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the (1)H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of gamma-oryzanol inside the lipid nanoparticles, the (1)H-NMR revealed that the chemical shifts of the liquid lipid in gamma-oryzanol loaded systems were found at rather higher field than those in gamma-oryzanol free systems, suggesting incorporation of gamma-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of gamma-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of gamma-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed.

Effect of Surfactant on Characteristics of Solid Lipid Nanoparticles (SLN)

SLN have shown a great promise as an alternative drug carrier for intravenous and dermal applications. This work focuses on the basic properties of drug-free Compritol® ATO 888 based SLN systems by using cationic surfactant (CPC) and nonionic surfactant (Tween 80). Effects of surfactant on the physical properties of SLNs were investigated in the absence of model drug to avoid the interaction between drug and surfactant. These SLN samples have different particle size, zeta potential and morphology. DSC was used to quantify the crystallinity of SLN systems. It was found that %RI of both SLNs was similar, indicating that types of surfactant did not affect on crystallization of solid lipid. Spherical-like particle was observed with SLN-C, while rod-like particle was found with SLN-T. The results demonstrated that surfactant plays an important role on SLN physical characteristics.

The effect of surfactant composition on the chemical and structural properties of nanostructured lipid carriers.

Abstract Fine-tuning the nanoscale structure and morphology of nanostructured lipid carriers (NLCs) is central to improving drug loading and stability of the particles. The role of surfactant charge on controlling the structure, the physicochemical properties and the stability of NLCs has been investigated using three surfactant types (cationic, anionic, non-ionic), and mixed surfactants. Either one, a mixture of two, or a mixture of three surfactants were used to coat the NLCs, with these classified as one, two and three surfactant systems, respectively. The mixed (two and three) surfactant systems produced smaller NLC particles and yielded NLCs with lower crystallinity than the one surfactant system. The combined effects of the ionic and the non-ionic surfactants may play a key role in assisting the lipid-oil mixing, as well as maintaining colloidal repulsion between NLC particles. In contrast, for the three surfactant system, the lipid–oil mixture in the NLCs appeared less homogenous. This was also reflected in the results of the stability study, which indicated that NLC particle sizes in two surfactant systems appeared to be retained over longer periods than for other surfactant systems.

One-step Preparation of Carbon-based Solid Acid Catalyst from Water Hyacinth Leaves for Esterification of Oleic Acid and Dehydration of Xylose

Carbon-based solid acid catalysts were successfully obtained via one-step hydrothermal carbonization (HTC) of water hyacinth (WH) in the presence of p-toluenesulfonic acid (PTSA). Increasing the HTC temperature from 180 to 240 °C resulted in carbonaceous materials with increased sulfur content and less adsorbed water. The material obtained at 220 °C (WH-PTSA-220) contains the highest amount of acid sites and promotes the highest initial rate of two transformations, that is, methanolysis of oleic acid and dehydration of xylose to furfural. While all PSTA-treated WH catalysts gave comparable fatty acid conversions (≈97 %) and furfural yields (≈60 %) after prolonged reaction times, the WH-PTSA-240 system bearing a relatively low acid density maintains the most favorable reusability profile. Higher HTC temperatures (220-240 °C) improved the catalyst reusability profiles due to graphitization and hydrophobicity of the carbon surface. The catalyst systems derived herein from biomass may have potential applications in biorefining platforms, utilizing the conversion of waste biomass to chemicals.

Rapid screening for anthocyanins in cane sugars using ESR spectroscopy

Anthocyanin, which is soluble in water and released into sugar steam during extraction, was investigated in this study. The anthocyanin content in refined sugar, plantation white sugar, soft brown sugar and raw sugar was determined using electron spin resonance (ESR) spectroscopy, which was operated at room temperature, and compared with spectra from standard anthocyanin. The ESR spectra of red and violet anthocyanins was predominantly g ≈ 2.0055, which corresponded to an unpaired electron located in the pyrylium ring. Signals for Fe(III) and Mn(II), which naturally occur in plants, were found in raw sugar, soft brown sugar and standard anthocyanin but were absent from refined sugar and plantation white sugar due to the refining process. In addition, the ESR results were correlated with the apparent colour of the sugar, which was determined using the method of the International Commission for Uniform Methods of Sugar Analysis and inductively coupled plasma optical emission spectroscopy.

Elemental analysis of burnt human bone for classifying sex and age at death by logistic regression

This study aims to develop a protocol for classifying sex and age groups of deceased persons by using the chemical information in burnt bone fragments. Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) has been employed to assess the chemical compositions of the burnt bones from the deceased, all of Thai nationality. By performing three ICP-OES measurements on burnt bone samples from 75 individuals, 43 males and 32 females, with an accurate record of their age at death, only six elements i.e. Al, Ca, K, Mg, P, S, were observed in the fragments above the instrumental detection limit of ICP-OES. Fifteen concentration ratios of these particular elements were examined for their significant difference with respect to sex and age group by Mann–Whitney U and Kruskal–Wallis tests, respectively. Subsequently, the significantly different ratios were employed to assess the relationship between bone chemical compositions and sex/age groups of the deceased using logistic regression analysis. Binary and multinomial logistic regressions were required to classify sex and age group at death, respectively. Regression analyses indicated that the input variables representing sex should be included for classifying the age group of the deceased. The chemical information in burnt bone fragments could be employed to assess the sex and age groups of the deceased with 79.60% and 75.10% accuracy, respectively. Chemical measurements were performed on burnt bone samples from two additional individuals to verify the developed logistic equations and classification protocol. More fractions of bones from an individual give a higher percentage of correction for classifying sex and age at death of the deceased.

ELECTRON SPIN RESONANCE INVESTIGATION OF FREE RADICALS PRODUCED IN PULVERIZED NON-IRRADIATED SUGAR

An electron spin resonance (ESR) study of the effects of pulverization on non-irradiated crystalline sugar was performed. It indicated that the crystalline sugar before being ground did not give any ESR signal but an ESR signal was found in pulverized sugar. These results implied that free radicals were produced by pulverization. Moreover, the free radical density increased as the particle size decreased. From high-performance liquid chromatography analysis and the ESR spectrum of non-irradiated powdered sucrose, it can be inferred that the pulverization-induced free radical in sugar is a sucrose radical. Recently, many researchers have reported that sugar irradiated with 60Co γ-rays at different doses produced stable sucrose radicals. This may imply that the process of sucrose radical formation by mechanical stress is similar to that for irradiation.

Low Temperature Solvolthermally Synthesized Nitrogen-Fluorine Doped TiO2 for Methyl Orange Photodegradation

A low temperature solvothermal method was employed to synthesize nitrogen-fluorine doped TiO2 materials (N/F -TiO2) at various mole ratio of Ti:F; 10:1, 10:0.3 and 10:0.1, for photocatalytic applications. Doping fluorine and nitrogen in the TiO2 structure extend the spectra response of the materials toward a visible region resulting in the high efficiency to oxidize methyl orange (MO) under UV-Vis irradiation. The microstructure and photocatalytic activity of the materials appeared to depend on titanium precursors, titanium isopropoxide (TTIP) or tetrabutyl orthotitanate (TBOT), and the concentration of dopant (NH4F). The highest MO decolorization efficiency under UV-Vis irradiation for 30 minutes is about 86 % by using N-F-TiO2 (TTIP precursor) with Ti: F of 10: 3 as catalyst. The decolorization efficiencies of MO over N-F-TiO2 materials (TTIP precursor) are twice higher than that of the undoped catalyst.