Optimization of polyol production via liquefaction from Acacia mangium and analysis of the polyols by traditional methods and two dimensional correlation spectroscopy

The aim was to optimize the liquefaction conditions of Acacia mangium wood flour with polyethylene glycol (PEG#400) as the solvent in the presence of sulfuric acid as a catalyst under atmospheric pressure. Reaction time (30–180 min), temperature (130–170°C), and the solvent ratio (PEG/glycerol=0–25%) were varied to obtain the lowest residue content. The resulting polyol was characterized by their hydroxyl number (OHN), acid number (AN), viscosity, molecular weight (Mw), thermogravimetric analysis, Fourier transform infrared (FT-IR) and two-dimensional correlation spectroscopy (2D-COS). The OHN was lowered, AN and Mw were elevated as a function of increasing the reaction temperature and the time. Introducing glycerol in the PEG system markedly increased the OHN, AN and viscosity of the liquefied wood. The optimum condition was 80/20% ratio of PEG/glycerol at 150°C in 150 min leading to a 75% liquefaction yield. The 1730 cm−1 band was indicative for the esters in the liquefied product. The 2D-COS analysis showed that lignin is easily liquefied at high temperatures and a decreasing amount of PEG, and that the presence of glycerol significantly enhanced the 1730 cm−1 band

Photocatalytic and Antibacterial Studies on Poly(Hydroxybutyrate-co-Hydroxyhexanoate) / Titanium Dioxide Composites

Bacteria and viruses causes food poisoning outbreaks. To prevent this, antimicrobial films can be used as packaging material or coatings on food processing surfaces. Titanium dioxide (TiO2) irradiated with ultraviolet light produces free radicals that can destroy organic contaminants and bacteria. U.S. Food and Drug Administration and the U.S. Pharmacopeia approves TiO2 as a colorant. Polyhydroxybutyrate is a bio-based polymer. Blends of this polymer are being studied for implants and drug delivery. TiO2 immobilized to blends of this polymer may be suitable in food processing. Poly(hydroxybutyrate-co-hydroxyhexanoate) and titanium oxide (PHB-HH/TiO2) composite films were irradiated under fluorescent and blacklight lamps. The results show that they can be activated by both lamps. However, the photocatalytic activity is higher in blacklight. The films were irradiated in the presence of Escherichia coli and Staphylococcus aureus. Both had a 0 log count when a 3% PHB-HH/TiO2 composite film was exposed to blacklight for 5 h. Exposure to fluorescent light showed some antibacterial activity. The photocatalytic activity of the films was enough to inhibit bacterial growth when exposed to fluorescent lamps. PHB-HH/TiO2 composite films have photocatalytic and antibacterial properties when exposed to fluorescent and blacklight lamps. The films can be used in the food industry

Molecular Mass and Localization of α-1,3-Glucan in Cell Wall Control the Degree of Hyphal Aggregation in Liquid Culture of Aspergillus nidulans

α-1,3-Glucan is one of the main polysaccharides in the cell wall of filamentous fungi. Aspergillus nidulans has two α-1,3-glucan synthase genes, agsA and agsB. We previously revealed that AgsB is a major α-1,3-glucan synthase in vegetative hyphae, but the function of AgsA remained unknown because of its low expression level and lack of phenotypic alteration upon gene disruption. To clarify the role of α-1,3-glucan in hyphal aggregation, we constructed strains overexpressing agsA (agsAOE) or agsB (agsBOE), in which the other α-1,3-glucan synthase gene was disrupted. In liquid culture, the wild-type and agsBOE strains formed tightly aggregated hyphal pellets, whereas agsAOE hyphae aggregated weakly. We analyzed the chemical properties of cell wall α-1,3-glucan from the agsAOE and agsBOE strains. The peak molecular mass of α-1,3-glucan from the agsAOE strain (1,480 ± 80 kDa) was much larger than that from the wild type (147 ± 52 kDa) and agsBOE (372 ± 47 kDa); however, the peak molecular mass of repeating subunits in α-1,3-glucan was almost the same (after Smith degradation: agsAOE, 41.6 ± 5.8 kDa; agsBOE, 38.3 ± 3.0 kDa). We also analyzed localization of α-1,3-glucan in the cell wall of the two strains by fluorescent labeling with α-1,3-glucan-binding domain–fused GFP (AGBD-GFP). α-1,3-Glucan of the agsBOE cells was clearly located in the outermost layer, whereas weak labeling was detected in the agsAOE cells. However, the agsAOE cells treated with β-1,3-glucanase were clearly labeled with AGBD-GFP. These observations suggest that β-1,3-glucan covered most of α-1,3-glucan synthesized by AgsA, although a small amount of α-1,3-glucan was still present in the outer layer. We also constructed a strain with disruption of the amyG gene, which encodes an intracellular α-amylase that synthesizes α-1,4-glucooligosaccharide as a primer for α-1,3-glucan biosynthesis. In this strain, the hyphal pellets and peak molecular mass of α-1,3-glucan (94.5 ± 1.4 kDa) were smaller than in the wild-type strain, and α-1,3-glucan was still labeled with AGBD-GFP in the outermost layer. Overall, these results suggest that hyphal pellet formation depends on the molecular mass and spatial localization of α-1,3-glucan as well as the amount of α-1,3-glucan in the cell wall of A. nidulans

Highly stabilized nanostructures from poly(L-lactide)-block-poly(oxyethylene) having a photoreactive end functionality

A photoreactive amphiphilic diblock copolymer was used to form stable nanostructures. The nanoparticles of the copolymer were prepared in an aqueous medium and photo-irradiated by atomic force microscopy (AFM). The particles were self-organized into long nanobands after heating. The nanobands and nanoparticles were stabilized by the photoreaction of the cinnamate groups

Biodegradability of Poly(hydroxyalkanoate) Materials

Poly(hydroxyalkanoate) (PHA), which is produced from renewable carbon resources by many microorganisms, is an environmentally compatible polymeric material and can be processed into films and fibers. Biodegradation of PHA material occurs due to the action of extracellular PHA depolymerase secreted from microorganisms in various natural environments. A key step in determining the overall enzymatic or environmental degradation rate of PHA material is the degradation of PHA lamellar crystals in materials; hence, the degradation mechanism of PHA lamellar crystals has been studied in detail over the last two decades. In this review, the relationship between crystal structure and enzymatic degradation behavior, in particular degradation rates, of films and fibers for PHA is described