Decay Resistance of Medium Density Fibreboard (MDF) Made from Pineapple Leaf Fiber

Medium density fiberboard (MDF) production is increasing due to the development of manufacturing technologies. MDF products are utilized for traditional wood applications that require fungal resistance. This study investigated some of the important biodegradation properties of MDF composite board made from renewable biomass from pineapple leaf fiber (Ananas comosus). The variable factors were type of board and type of resin. Two different types of board with a target density of 0.8 g/cm3 were manufactured. The boards were prepared in three layers of about 1:1:1 weight ratio in crossoriented and unidirectional pattern, using low molecular weight (LM) phenol formaldehyde (PF) resin type PL-3725 and high molecular weight (HM) PF resin type PL-2818 for impregnation and adhesive purposes. Decay resistance (white and brown rot fungi) of the MDF was evaluated to assess its biological performance. In this study, fiber orientation had no effect on the decay resistance to white and brown rot fungi of the specimens. However, a slight increase was found for the mass loss of the low molecular weight PF resin board specimens compared with the mixed low and high molecular PF resin board specimens. The total resin content of 20% of the type I boards prohibits degradation by decay

Stereospecificity of Thermostable Ornithine 5-Aminotransferase for the Hydrogen Transfer in the L- and D-Ornithine Transamination (MOLECULAR BIOFUNCTION-Molecular Microbial Science)

The thermostable ornithine 5-aminotransferase of a thermophile, Bacillus sp. YM-2 is unique in acting on both enantiomers of ornithine, although less effectively on the D-enantiomer. We studied the stereospecificity of the enzyme for the hydrogen abstraction from C-5 of the substrate moiety and the addition and removal of the hydrogen at C-4' of the cofactor (pyridoxal phosphate and pyridoxamine phosphate) moiety of the external Schiff base intermediate in the transamination of L- and D-ornithine. [5- 3H]L- and D-ornithines were prepared by incubation of L- and D-ornithines with the B. sp. YM-2 ornithine 5-aminotransferase in 3H2O, respectively. The C-5 of the tritiated L-and D-ornithine was proved to have the S-configuration with L-ornithine 5-aminotransferase of a mesophile, Bacillus sphaericus, catalyzing the stereospecific abstraction of pro-S hydrogen from C-5 of L-ornithine and amino acid racemase with lowsubstrate specificity of Pseudomonas putida . When apo-form of the enzyme was incubated with pyridoxamine 5'-phosphates that was stereospecifically tritiated at C-4' and 2-oxoglutarate in the presence of L-ornithine or D-ornithine, tritium was released exclusively from (4'S)-[4'-3H] pyridoxamine. These results suggest that the B. sp. YM-2 ornithine 5-aminotransferase stereospecifically abstracts the pro-S hydrogen from C-5 of L- and D-ornithine. The hydrogen abstracted is then transferred to C-4' of the cofactor moiety stereospecifically on the si face of the external Schiff base intermediate irrespective of the C-2 configuration of amino donor

Evaluation of termite resistance of medium density fiberboard (MDF) manufacture from agricultural fiber bonded with citric acid

The 5th Sustainable Future for Human Security (SustaiN 2014)Nowadays, the use of agricultural fibers for panel composite materials attracts great intention. Further, it is desirable to develop of natural adhesive derived from non fossil resources to be safe adhesive without using harmful chemical substances. In this study, citric acid application as natural adhesive was investigated for medium density fiberboard (MDF) manufacture from pineapple leaf fiber. The ratio of citric acid and sucrose and adhesive content was 25–75 and 20 wt%, respectively. Two different types of board consisting of three layers with target density of 0.8 gr/cm³ were prepared. The board was hot pressed at 200 °C and 4.5 MPa for 10 min.Additionalboards with same structure were prepared using citric acid only. The biological properties of the boards such as their resistance against subterranean termite attack have been examined. The results indicate that generally, there was a significant effect of impregnation with mixture of citric acid and sucrose and citric acid only on the susceptibility of the MDF board specimens. With regards to the percentage of specimen mass losses, fiber orientation had no significant effect on the termite resistance against Coptotermes formosanus Shiraki. Utilization of natural adhesive, citric acid was promising to be used for MDF manufacturing. Our findings show that the total adhesive content of 20% of the type a board could be used for agricultural fiber product applications to protect structures from degradation by termites

Nature of collective decision-making by simple yes/no decision units Eisuke Hasegawa

The study of collective decision-making spans various fields such as brain and behavioural sciences, economics, management sciences, and artificial intelligence. Despite these interdisciplinary applications, little is known regarding how a group of simple 'yes/no' units, such as neurons in the brain, can select the best option among multiple options. One prerequisite for achieving such correct choices by the brain is correct evaluation of relative option quality, which enables a collective decision maker to efficiently choose the best option. Here, we applied a sensory discrimination mechanism using yes/no units with differential thresholds to a model for making a collective choice among multiple options. The performance corresponding to the correct choice was shown to be affected by various parameters. High performance can be achieved by tuning the threshold distribution with the options' quality distribution. The number of yes/no units allocated to each option and its variability profoundly affects performance. When this variability is large, a quorum decision becomes superior to a majority decision under some conditions. The general features of this collective decision-making by a group of simple yes/no units revealed in this study suggest that this mechanism may be useful in applications across various fields

Assessment of macular choroidal thickness by optical coherence tomography and angiographic changes in central serous chorioretinopathy.

[Objective]: To investigate the relationship between macular choroidal thickness measured by highpenetrating swept-source optical coherence tomography (SS-OCT) and angiographic findings in central serous chorioretinopathy (CSC). [Design]: Prospective cross-sectional case series. [Participants and Controls]: Thirty-four patients with CSC (44 eyes) and 17 volunteer subjects (17 normal eyes). [Methods]: All subjects underwent a comprehensive ophthalmologic and SS-OCT prototype examination. All patients with CSC also underwent simultaneous fluorescein angiography (FA) and indocyanine green angiography (IA). Mean regional choroidal thickness measurements on the Early Treatment Diabetic Retinopathy Study (ETDRS) layout and squared sector grids were obtained by 3-dimensional raster scanning using SS-OCT. [Main Outcome Measures]: Macular choroidal thickness and angiographic abnormalities. [Results]: Mean whole macular choroidal thickness in eyes with CSC (total, 329.3_83.0 _m; classic CSC, 326.9_83.1 _m; chronic CSC, 325.4_93.3 _m; and multifocal posterior pigment epitheliopathy, 359.0_15.5 _m) was greater than that in normal eyes (233.0_67.0_m) (P_ 0.001). In unilateral cases, mean whole macular choroidal thickness was greater in eyes with unilateral CSC than in unaffected fellow eyes (P_0.021). There was no significant difference in choroidal thickness between active eyes and resolved eyes in any of the ETDRS sectors. Mean choroidal thickness was greater in areas with leakage on FA than in areas without leakage (P_0.001). Mean choroidal thickness was greater in areas with choroidal vascular hyperpermeability and in areas with punctate hyperfluorescent spots on IA than in unaffected areas (P_0.001 for both). [Conclusions]: Increased choroidal thickness was observed in the whole macular area of eyes with any of the CSC subtypes. Choroidal thickness was related to leakage from the retinal pigment epithelium, choroidal vascular hyperpermeability, and punctate hyperfluorescent lesions. These findings provide evidence that CSC may be caused by focally increased hydrostatic pressure in the choroid. [Financial Disclosure(s)]: Proprietary or commercial disclosure may be found after the references