Development of polyelectrolyte multilayer-coated electrospun cellulose acetate fiber mat as composite membranes

Electrostatic multilayers of chitosan (CHI)/sodium alginate (SA) and CHI/poly(styrene sulfonate) sodium salt (PSS) were alternatively coated on electrospun cellulose acetate (CA) fiber mat. Morphologies of the composite membranes were characterized by scanning electron microscopy. The morphology of the CHI/SA-coated membrane was denser than the CHI/PSS-coated one. The top layers consisted of carboxyl and sulfonic functional groups for SA and PSS layers, respectively. Amino groups of CHI were only presented in slight quantity. X-ray photoelectron spectroscopy (XPS) confirmed the deposition of the amino groups of CHI on the multilayer membrane surface. These composite membranes were characterized for its water permeability where the water flux decreased with an increase in the number of the bilayers. The water flux was in the range of 60 and 40 L m⁻² h⁻¹ for 15 and 25 bilayered membranes, respectively. The sodium chloride (NaCl) solution flux was lower than the pure water flux due to the effect of osmotic pressure, and it decreased with an increase in the NaCl concentration. The rejection of NaCl increased substantially with the number of the bilayers of the polyelectrolytes multilayers. The level of NaCl rejection from this work was in the range of 6% and 15% for 15 and 25 bilayered membranes, respectively.     

Magnesium Oxide-Catalyzed Conversion of Chitin to Lactic Acid

Although chitin, an N-acetyl-D-glucosamine polysaccharide, can be converted to valuable products by means of homogeneous catalysis, most of the chitin generated by food processing is treated as industrial waste. Thus, a method for converting this abundant source of biomass to useful chemicals, such as lactic acid, would be beneficial. In this study, we determined the catalytic activities of various metal oxides for chitin conversion at 533 K and found that MgO showed the highest activity for lactic acid production. X-ray diffraction analysis and thermogravimetry-differential thermal analysis showed that the MgO was transformed to Mg(OH)₂ during chitin conversion. The highest yield of lactic acid (10.8 %) was obtained when the reaction was carried out for 6 h with 0.5 g of the MgO catalyst. The catalyst could be recovered as a solid residue after the reaction and reused twice with no decrease in the lactic acid yield.     

Beneficial Effects of Cyclic Ether 2-Butoxytetrahydrofuran from Sea Cucumber Holothuria scabra against Aβ Aggregate Toxicity in Transgenic Caenorhabditis elegans and Potential Chemical Interaction

The pathological finding of amyloid-β (Aβ) aggregates is thought to be a leading cause of untreated Alzheimer’s disease (AD). In this study, we isolated 2-butoxytetrahydrofuran (2-BTHF), a small cyclic ether, from Holothuria scabra and demonstrated its therapeutic potential against AD through the attenuation of Aβ aggregation in a transgenic Caenorhabditis elegans model. Our results revealed that amongst the five H. scabra isolated compounds, 2-BTHF was shown to be the most effective in suppressing worm paralysis caused by Aβ toxicity and in expressing strong neuroprotection in CL4176 and CL2355 strains, respectively. An immunoblot analysis showed that CL4176 and CL2006 treated with 2-BTHF showed no effect on the level of Aβ monomers but significantly reduced the toxic oligomeric form and the amount of 1,4-bis(3-carboxy-hydroxy-phenylethenyl)-benzene (X-34)-positive fibril deposits. This concurrently occurred with a reduction of reactive oxygen species (ROS) in the treated CL4176 worms. Mechanistically, heat shock factor 1 (HSF-1) (at residues histidine 63 (HIS63) and glutamine 72 (GLN72)) was shown to be 2-BTHF’s potential target that might contribute to an increased expression of autophagy-related genes required for the breakdown of the Aβ aggregate, thus attenuating its toxicity. In conclusion, 2-BTHF from H. scabra could protect C. elegans from Aβ toxicity by suppressing its aggregation via an HSF-1-regulated autophagic pathway and has been implicated as a potential drug for AD.     

Statistical optimization of biodiesel production from para rubber seed oil by SO3H-MCM-41 catalyst

The experimental parameters for biodiesel production from para rubber seed oil and methanol using a SO₃H-MCM-41 catalyst were optimized statistically. The SO₃H-MCM-41 catalyst was synthesized by co-condensation in the presence of tetraethyl orthosilicate, 3-mercaptopropyl (methyl) dimethoxysilane (MPMDS) and cetyl-trimethylammonium bromide. In the last step, the solid catalyst (SH-MCM41) was oxidized by H₂O₂ to SO₃H-MCM-41. The acid capacity of the obtained SO₃H-MCM-41 catalyst was quantified by back titration with 0.1 M sodium hydroxide. The physical and chemical properties of the SO₃H-MCM-41 were characterized by nitrogen adsorption/desorption, X-ray diffractometry, Fourier transform infrared spectroscopy and thermogravimetric analysis. The effect of varying the catalyst loading (wt.%), reaction time (h) and temperature (°C) and molar composition of MPMDS on the biodiesel yield were investigated using a 2^k factorial design. The optimal conditions to maximize the biodiesel yield, obtained from the response surface analysis using a Box–Behnken design, was a 14.5 wt.% catalyst loading, and a reaction time and temperature of 48 h and 129.6 °C. Under these conditions a fatty acid methyl ester (biodiesel) yield of 84% was predicted, and an 83.10 ± 0.39% yield experimentally obtained.     

Influence of Al2O3 and P2O5 contents in sol-gel ionomer glass system on the structure and their cement properties

Journal of Sol-Gel Science and Technology - Glass ionomer dental cement (GIC) is commonly used as a restorative material. The sol-gel synthesis of the ionomer glass is an alternative method, which...     

A facile one-step way for extraction of nanocellulose with high yield by ball milling with ionic liquid

93.1% yield of nanocellulose was successfully extracted from cellulose powder (CP) by planetary ball milling in the presence of ionic liquid (IL) of 1-butyl-3-methylimidazolium chloride (BMIMCl). The morphology of nanofibrillated cellulose present in fibrous network with 10–25 nm in diameter and micrometer scale in length and the chemical composition and crystal structure were maintained as cellulose type I. At 600 °C degradation temperature, the residue amount of the obtained nanocellulose was about 55% more that of CP, implying it had higher thermal stability. The used BMIMCl was recovered and reused at least 4 times. The nanocellulose obtained by using the recovered IL also demonstrated the same properties as those from the fresh one. For comparison, another kind of IL of 1-ethyl-3-methylimidazolium acetate (EMIMOAc) was also used in this study. It is found that the ball milling of cellulose in the presence of IL is an effective and environmental friendly way for the production of nanocellulose with high yield.     

Isolation and Structure Elucidation of Enniatins L,M1, M2, and N: Novel Hydroxy Analogs

Four new cyclohexadepsipeptides, enniatins L ( 1 ), M₁ ( 2 ), M₂ ( 3 ), and N ( 4 ), have been isolated from an unidentified fungus (BCC 2629), together with the known enniatins B ( 5 ), H ( 6 ), and I ( 7 ), MK1688 ( 8 ), and enniatin B₄ ( 9 ). Compounds 1 – 4 are the first enniatin analogs with an OH group at the side chain of one of the 2‐hydroxycarboxylic acid residues. The structures of 1 – 4 were elucidated by spectroscopic means and by X‐ray crystallography.     

Ultrasound-assisted extraction of anthraquinones from roots of Morinda citrifolia

This study investigated the use of ultrasound-assisted extraction (UAE) to improve the extraction efficiency of the classical solvent extraction techniques such as maceration and soxhlet extraction to extract anti-oxidant activity compounds, anthraquinones, from the root of Morinda citrifolia. The effects of different extraction conditions were determined, i.e., temperature of (25, 45, 60 °C), ultrasonic power, solvent types, and compositions of ethanol in ethanol–water mixtures. The results show that the yield increases with increasing extraction times and extraction temperatures. The percent recovery of anthraquinones using ultrasound was found to be highly dependent on the type of solvents (acetone > acetonitrile > methanol > ethanol). Furthermore, the use of ethanol–water solution as extraction solvent increased the yield of anthraquinones due to the relative polarity, the swelling effect of plant tissue matrix by water, and increased sound absorption. To achieve the same recovery as that achieved by UAE, soxhlet extraction and maceration required much longer time.