Treatment of acidic palm oil for fatty acid methyl esters production

Acidic crude palm oil (ACPO) produced from palm oil mills with an acid value of 18 mg g⁻¹ was considered to be a possible feedstock for biodiesel production. Due to its high acidity, conventional transesterification cannot be applied directly for biodiesel production. Methane sulphonic acid (MSA, CH₃SO₃H) is used to reduce the acidity prior to the alkaline transesterification reaction. The laboratory-scale experiments involved an MSA to ACPO dosage of 0.25–3.5 %, a molar ratio (methanol to ACPO) from 4: 1 to 20: 1, reaction temperature of 40–80°C, reaction time of 3–150 min, and stirrer speed of 100–500 min⁻¹. The optimum esterification reaction conditions were 1 % of catalyst to ACPO, with a molar ratio of methanol to ACPO of 8: 1, a stirring speed of 300 min⁻¹, for 30 min and at 60°C. Under these conditions, the FFA content was reduced from 18 mg g⁻¹ to less than 1 mg g⁻¹ and with a yield of 96 %. The biodiesel produced met the EN14214 standard specifications. MSA was recycled for three times without losing its activity. The biodiesel produced in a two-stage process has a low acid value (0.14 mg g⁻¹).     

Physicochemical characterization of natural-like branched-chain glycosides toward formation of hexosomes and vesicles

Synthetic branched-chain glycolipids have become of great interest in biomimicking research, since they provide a suitable alternative for natural glycolipids, which are difficult to extract from natural resources. Therefore, branched-chain glycolipids obtained by direct syntheses are of utmost interest. In this work, two new branched-chain glycolipids are presented, namely, 2-hexyldecyl β(α)-D-glucoside (2-HDG) and 2-hexyldecyl β(α)-D-maltoside (2-HDM) based on glucose and maltose, respectively. The self-assembly properties of these glycolipids have been studied, observing the phase behavior under thermotropic and lyotropic conditions. Due to their amphiphilic characteristics, 2-HDG and 2-HDM possess rich phase behavior in dry form and in aqueous dispersions. In the thermotropic study, 2-HDG formed a columnar hexagonal liquid crystalline phase, whereas in a binary aqueous system, 2-HDG formed an inverted hexagonal liquid crystalline phase in equilibrium with excess aqueous solution. Furthermore, aqueous dispersions of the hexagonal liquid crystal could be obtained, dispersions known as hexosomes. On the other hand, 2-HDM formed a lamellar liquid crystalline phase (smectic A) in thermotropic conditions, whereas multilamellar vesicles have been observed in equilibrium with aqueous media. Surprisingly, 2-HDM mixed with sodium dodecyl sulfate or aerosol OT induced the formation of more stable unilamellar vesicles. Thus, the branched-chain glycolipids 2-HDG and 2-HDM not only provided alternative nonionic surfactants with rich phase behavior and versatile nanostructures, but also could be used as new drug carrier systems in the future.     

Room temperature Ge and ZnO embedded inside porous silicon using conventional methods for photonic application

In this paper we reported room temperature synthesis of embedded porous Si (PS) based structures using simple and low cost techniques of electrochemical etching and thermal evaporation. PS was prepared by anodization of Si wafer in ethanoic hydrofluoric acid (HF). The Ge and ZnO layers were deposited onto the PS by conventional thermal evaporation. Three samples prepared namely PS, Ge/PS and ZnO/Ge/PS. Structural analyses, SEM revealed that the structures contained 500–700 nm circular-pores and EDX suggested the presence of Ge and ZnO inside the pores. Photoluminescence (PL) spectra of the three samples revealed emissions peak at 380, 520 and 639 nm, respectively, with ZnO/Ge/PS displaying a high UV emission peak accompanied by low and broad green to red emission peaks. The Ge/PS sample shows emission peaks from green to red and the PS sample reveals a broad peak in the red region. These characteristics demonstrate the potential of the PS-based structures to emit light at a broader spectrum for prospective applications in optoelectronic devices.     

Optical properties of lithium magnesium borate glasses doped with Dy and Sm ions

Several studies showed the interesting properties of trivalent lanthanide ions when doped in various types of glasses. Optical and physical properties of lithium magnesium borate glasses doped with Dy³⁺ then with Sm³⁺ ions were determined by measuring their absorption and luminescence spectra in the visible region. The absorption spectra of Dy³⁺ showed eight absorption bands with hypersensitive transition at 1265 nm (⁶H_15/2→⁶F_11/2-⁶H_9/2) and three PL emission bands at 588 nm (⁴F_9/2→⁶H_15/2), 660 nm (⁴F_9/2→⁶H_13/2) and 775 nm (⁴F_9/2→⁶H_11/2). Regarding the Sm3⁺, nine absorption bands were observed with hypersensitive transition at 1237 nm (⁶H_5/2–⁶F_7/2); the PL spectrum showed four prominent peaks at ⁴G_5/2→⁶H_5/2 (yellow color), ⁴G_5/2→⁶H_7/2 (bright orange color), ⁴G_5/2→⁶H_9/2 (orange reddish color) and ⁴G_5/2→⁶H_11/2 (red color), respectively. Finally, a series of physical parameters such as the oscillator strengths, refractive index, ions concentration, Polaron radius and other parameters were calculated for each dopant.     

Molecular dynamics simulation of monoalkyl glycoside micelles in aqueous solution: influence of carbohydrate headgroup stereochemistry

Comparative molecular dynamics simulations of n-octyl-beta-D-galactopyranoside (beta-C8Gal) and n-octyl-beta-D-glucopyranoside (beta-C8Glc) micelles in aqueous solution have been performed to explore the influence of carbohydrate stereochemistry on glycolipid properties at the atomic level. In particular, we explore the hypothesis that differences in T(m) and T(c) for beta-C8Gal and beta-C8Glc in lyotropic systems arise from a more extensive hydrogen bonding network between beta-C8Gal headgroups relative to beta-C8Glc, due to the axial 4-OH group in beta-C8Gal. Good agreement of the 13 ns micelle-water simulations with available experimental information is found. The micelles exhibit a similar shape, size, and degree of exposed alkyl chain surface area. We find net inter- and intra-headgroup hydrogen bonding is also similar for beta-C8Gal and beta-C8Glc, although n-octyl-beta-D-galactopyranoside micelles do exhibit a slightly greater degree of inter- and intra-headgroup hydrogen bonding. However, the main distinction in the calculated microscopic behavior of beta-C8Glc and beta-C8Gal micelles lies in solvent interactions, where beta-d-glucosyl headgroups are considerably more solvated (mainly at the equatorial O4 oxygen). These results agree with preceding theoretical and experimental studies of monosaccharides in aqueous solution. A number of long water residence times are found for solvent surrounding both micelle types, the largest of which are associated with surface protrusions involving headgroup clusters. Our simulations, therefore, predict differences in hydrogen bonding for the two headgroup stereochemistries, including a small difference in inter-headgroup interactions, which may contribute to the higher T(m) and T(c) values of beta-C8Gal surfactants relative to beta-C8Glc in lyotropic systems.     

Pyridinedithioesters as heterodienophiles: application to the synthesis of aprikalim

[reaction: see text] Pyridinedithioesters can be used as efficient heterodienophiles when activated by complexation with BF(3), by protonation, or by oxidation of the nitrogen atom of the pyridine moiety. The hetero-Diels-Alder reaction using 3-pyridinedithioester as a heterodienophile was the key step in a new synthesis of Aprikalim in racemic form. The methodology can be reliably extended to prepare new analogues of Aprikalim.     

Preparation of dihydrotetrazolo[1,5-a]pyrimidine derivatives from Biginelli 3,4-dihydropyrimidine-2-thiones

Dihydropyrimidines (DHPM) with a fused tetrazole ring have been synthesized via a smooth and efficient three-step protocol involving N,S-dimethylated and 2-hydrazinyl-dihydropyrimidine intermediates, respectively. The described protocol is applicable to electron rich and electron poor DHPM precursors as well. The insertion of tetrazole ring in monastrol type dihydropyrimidines makes it interesting for pharmacological investigations.     

Cytotoxic cembranoids from the Red Sea soft coral, Sarcophyton auritum

Chemical investigation of the Red Sea soft coral Sarcophyton auritum led to the isolation and structure elucidation of two new diterpene cembranoids; 2-epi-sarcophine (2) and (1R,2E,4S,6E,8R,11R,12R)-2,6-cembradiene-4,8,11,12-tetrol (4), as well as two known diterpene cembranoids, reported for the first time from this species, namely sarcophine (1) and (+)-7α,8β-dihydroxydeepoxysarcophine (3). Structure elucidation was achieved using spectroscopic techniques, including 1D and 2D NMR and HRMS. The isolated cembranoids were found to display high cytotoxicity against HepG2 (liver cancer cell line) and MCF-7 (breast cancer cell line).     

Stereoselective and Convenient Synthesis of Diethyl (E)-α-Triphenylstannyl or (Z)-α-Tributylstannyl α-Alkenylphosphonates

Diethyl (E)-α-triphenylstannyl or (Z)-α-tri-n-butylstannyl α-alkenylphosphonates are conveniently and stereoselectively prepared using a “tin-Peterson-like” reaction. Protonolysis of the carbon-tin bond of α-tributylstannyl derivatives proved to be easy and stereospecific.     

Ultra Moisturizing Skin Whitening Lotion Enriched with Tocotrienols

A two-in-one product, a skin whitening lotion enriched with tocotrienols that ultra moisturizes and lightens, was successfully prepared. The basic formulation for this product was prepared by constructing a ternary phase diagram consisting of medium chain triglycerides (MCT), mixed glucose-based emulsifiers, and deionized water at 80°C. The right ratio of these compounds was selected based on liquid crystalline region to produce a stable product. Other palm-based materials were added to the basic formulation. The product was found to be stable for more than 3 months upon storage stability test. The mean droplet size is 10 µm with a monomodal distribution pattern which prevents agglomeration. This decreases Brownian motion, thus prolonging its stability. Long-term acute moisturizing tests showed a significant increase of between 21.2% and 15.4% hydration for 5 and 6 weeks, respectively. The efficacy testing on 20 subjects confirmed a reduction in melanin content, lightening the skin in 4 weeks.