Mechanism Of Deconstruction Research Articles

Comparison of Insect Gut Cellulase and Xylanase Activity Across Different Insect Species with Distinct Food Sources

Insect guts represent unique natural biocatalyst systems for biocatalyst discovery and biomass deconstruction mechanism studies. In order to guide the further research for enzyme discovery and biodiversity analysis, we carried out comprehensive xylanase and cellulase activity assays for the gut contents of three insect species representing different orders and food sources. The three insect species are grasshopper (Acrididae sp.), woodborer (Cerambycidae spp.), and silkworm (Bombyx mori) to represent the wood-consuming, grass-consuming, and leaf-consuming insects from Orthoptera, Coleoptera, and Lepidoptera orders, respectively. Generally speaking, the enzyme activity assays have shown that the cellulase and xylanase activities for grasshopper and woodborer guts are significantly higher than those of silkworm under various conditions. In addition, both pH and temperature have a significant impact on the enzyme activities in the gut contents. For the grasshopper gut, the means of xylanase and cellulase activities at pH 7 were 3,397 and 404 μM mg−1 min−1, which are significantly higher than the activities at pH 4 and 10 (P < 0.05). However, woodborer guts have shown the highest cellulase activity at pH 10. The results suggested that systems similar to woodborer guts could be good resources for discovering alkaline-tolerant enzymes. Moreover, the enzyme activities in response to different substrate concentrations were also analyzed, which indicated that grasshopper gut had particularly high cellulase activity. The enzyme activities in response to the reaction time were also examined, and we found that the enzyme activities (micromolar per milligram per minute) of different insect gut juices in response to the increase of incubation time fit well to the power function equation (E c = K ⋅ t b ) with high coefficients (r 2 > 0.99). The newly developed model serves well to compare the characteristics of the enzyme mixtures among different insect species, which can be applied to other studies of natural biocatalyst systems for the future. Overall, the data indicated that grasshopper and woodborer guts are valuable resources for discovering the novel biocatalysts for various biorefinery applications.

Knowledge society: Mechanisms of deconstruction

The coming phase in the history of civilization is conditioned by a special economic role of knowledge, which has recently manifested itself. However, the established existence contradicts the cultural traditions of the social group whose lifestyle has historically formed in a scientific environment. Now they cannot find sufficient socioeconomic support in society and in its system of education. Discovering new knowledge and involving it in the sociocultural context is not yet a vital value for society but a way to replenish one of the “tributes” that deplete its potentialities to acquire the culture of knowledge. Further, we will consider some of the acting mechanisms that deconstruct knowledge society. Cognitive inflation of the knowledge production sphere. Here, two factors are especially important: first, the socioeconomic realities, which detach scientists from knowledge production and instead generate conditions that can be endured only in the forms of radical material asceticism, and, second, the reduction to zero of the values of knowledge society by those who consider its creators’ material benefits as a means to satisfy title idleness. Factors that detach young people from engagement in science can be revealed by the results of sociological polls. In 2002, 49.6% of respondents in 15 countries of the European Union, according to the Eurobarometer data, stressed a lessened attractiveness of work in the scientific sphere, while 42.5%, a lack of career prospects and insufficient salaries [1]. We can compare the European data with the statistics of Russian surveys [2]. Young people of our country indicate low salaries as the main factor associated with the impossibility to work at scientific institutions, 85%. The lack of demand for scientists raises concern in 17% of respondents, while limited career opportunities, concerns only 12%. Comparing the above data with the results of polling young Russian scientists on emigration factors, note their similarity in the main parameter: 89% of respondents pointed to the low level of labor compensation, while 39% of them differed on career opportunities (as opposed to 12% in the “problem” poll). This figure is sufficiently close to the Eurobarometer data in the “trouble-free” abroad. We can also mark a similarity of opinions on the attractiveness of jobs in the scientific

Reactivity and deconstruction of the (1×2)-Rh(110) surface studied by scanning tunneling microscopy

The titration of a (2×2)p2mg–O/Rh(110) surface by hydrogen and the subsequent deconstruction of the nonequilibrium (1×2) reconstructed surface has been studied by scanning tunneling microscopy (STM) in a temperature range between 380 and 405 K. The titration reaction is seen to occur via reaction fronts, which start at steps, are elongated in the [11̄0] direction and leave behind a surface covered by diffusing oxygen atoms. Two deconstruction mechanisms are active: A long-range row pairing of adjacent (1×2) rows, which propagates over several hundreds of Å in the [11̄0] direction, and a local hole formation in which Rh atoms detach from the ends of broken [11̄0] rows, diffuse over up to 100 Å and condense into (1×1) islands. Both mechanisms lead to the formation of correlated up–down islands; at step edges, the second one leads to a step retraction. The deconstruction is strongly defect mediated and the STM results indicate that the (1×2) reconstructed surface is most probably metastable.

Deconstruction mechanism of Si(111)—(2 × 1) surface upon chemisorption of hydrogen

The structural change from the (2 × 1) to the (1 × 1) form at low coverage of hydrogen was considered to be inconsistent with the π-bonded chain model of Pandey. In this report a mechanism of deconstruction is proposed that is able to convert the chain surface to the (1 × 1) form, and at the same time is compatible with the LEED vs coverage measurements. Energetics of bonds and the calculated state densities are shown to favor this mechanism.