Effect Of Moisture Treatment Research Articles

Evaluation of moisture diffusion characteristics and the effect of moisture treatment on flexural properties of expanded perlite-based building material

The expanded perlite-based building material for drywall application consisting of sodium silicate solution as a binder was manufactured by varying the degree of compaction and sodium silicate content to investigate moisture diffusion behavior and the effect of moisture treatment on flexural properties of the composites. Moisture treatment was conducted on specimens in a climatic chamber at a temperature of 37°C and a relative humidity of 90% until saturation. Results show that moisture absorption decreased with increasing compaction ratio for a constant sodium silicate content in binder and increased with increasing sodium silicate content in binder for a constant compaction ratio. A range of volume fractions of solid sodium silicate in the foam is identified, in which the fully Fickian diffusion gradually transformed to non-Fickian diffusion as sodium silicate content in foam increased. The concentration-dependent diffusion method was found to be suitable to explain this behavior. The moisture diffusion below this transition range showed an entirely Fickian diffusion and changed to concentration-dependent diffusion above the range. As a result of moisture treatment, the flexural strength of medium density foams was decreased but the lowest- and highest-density foams were not affected while the flexural modulus was increased only for the highest density foam and no significant effects were seen in other cases. The bending failure mechanism of the composite was not affected by the moisture treatment.

Soil pore size distribution shaped not only compositions but also networks of the soil microbial community

Soil pore size and arrangement control the heterogeneous distribution of nutrients, water, and air and, therefore, are likely a superimposed and integrated factor dictating the soil microbial community structure. It is known that soil with more large pores can potentially harbor more diverse microbes under low hydraulic connectivity. Still, there is scant information on how soil pore size distribution (PSD) governs the composition and association of the microbial community. This work examined PSD effects on microbial community compositions and networks via marker gene high-throughput sequencing of both DNA and cDNA. Three soils with a large variation in silt content (~11–73%) and their combinations at different mass ratios were used to enhance the continuity in silt content and thus PSD. Investigations were made under different levels of total pore volume and pore hydraulic connectivity by incubating soils at varied bulk densities and moisture contents for 50 days. The total of six soils was dichotomized into two PSD groups based on soil water retention curves, with PSD-1 of more macro- and mesopores (>30 μm) and PSD-2 of more micropores (<30 μm). Effects of moisture treatments on both fungal and bacterial evenness and Shannon diversity index were pore size group specific, supporting the importance of pore hydraulic connectivity in regulating microbial diversity. PSD-1 soils promoted the proliferation of Betaproteobacteria, Bacteroidetes, and Eurotiales, whereas PSD-2 soils favored Alphaproteobacteria, Sordariomycetes, and Chaetothyriales. Pore hydraulic connectivity slightly and yet significantly affected the microbial relative abundance of PSD-2 soils, with Actinobacteria being more abundant under drier conditions. There were less intra- and interkingdom associations in PSD-2 than PSD-1 soils, and such differences were little affected by pore volume and pore hydraulic connectivity. Our work highlighted PSD-dependent soil microbial distributions and associations, but ecological consequences need to be further examined.

Critical Current Density Enhancement and Moisture Destruction Studies of the Compound Superconductor Y-Ba-Cu-Ag-O

ABSTRACTWe have fabricated a series of samples of YBa2(Cu1−x Agx)3Oy compounds where 0 ≤ × ≤ 1, with the intention to study the changes in critical current density and the effect of moisture treatment on normal state resistance R in these high transition-temperature superconductors. The samples exhibited a decrease of the transition-temperature Tc vs the Ag concentration x. Tc is about 93 K for YBa2Cu3Oy and 20 KCfor YBa2Ag3Oy, but it is almost unaffected by the presence or Ag for × &lt; 0.2. An enhancement of the critical current density Jc by nearly an order of magnitude for the samples with 0 &lt; × ≤ 0.1 has been observed. Both Jc and R are found to be sensitive to the ambient moisture conditions.