A Complex Review of the Possibilities of Residual Stress Analysis Using Moving 2D and 3D Digital Image Correlation System

Understanding the levels of residual stresses in the material is very important in predicting the service life of structural elements. One of the most widely used techniques to quantify them is the drilling method, where a small hole is milled in the structure. If the residual stresses are present, stress redistribution will occur, resulting in deformation of the hole surroundings. Nowadays, there is an effort to replace the conventionally used strain gauges, i.e. special strain gauge rosettes, with full-field optical experimental techniques. This paper deals with analysing the possibilities of measuring the relieved strains/stresses with a unique drilling/measuring device, which, unlike other non-commercial measuring systems, uses the moving digital image correlation (DIC) system. Since correlation systems do not tend to move during operation, an analysis was performed describing the effect of changing the position of the single and stereo camera correlation systems on the quality of the results of the strain/stress analysis performed in the vicinity of the milled hole. The conclusion from the analyses performed is that there is no significant accumulation of correlation errors during measurement. Therefore, the information on the magnitudes of the strains/stresses relieved obtained by the moving DIC system can be used to quantify the residual stresses with an expected error corresponding to the sensitivity of this full-field optical experimental technique.

Proteome sequencing and analysis of Ophiocordyceps sinensis at different culture periods

Background Ophiocordyceps sinensis is an important traditional Chinese medicine for its comprehensive active ingredients, such as cordycepin, cordycepic acid, and Cordyceps polysaccharide. O. sinensis zjut, a special strain isolated from O. sinensis, has similar pharmacological functions to wild O. sinensis. Currently, O. sinensis with artificial cultivation has been widely studied, but systematic fundamental research at protein levels has not been determined. Results Proteomes of O. sinensis zjut at different culture periods (growth period, 3rd day; pre-stable period, 6th day; and stable period, 9th day) were relatively quantified by relative isotope markers and absolute quantitative technology. In total, 4005 proteins were obtained and further annotated with Gene Ontology, Kyoto Encyclopedia of Genes and Genomes database. Based on the result of the annotations, metabolic pathways of active ingredients, amino acids and fatty acid were constructed, and the related enzymes were exhibited. Subsequently, comparative proteomics of O. sinensis zjut identified the differentially expressed proteins (DEPs) by growth in different culture periods, to find the important proteins involved in metabolic pathways of active ingredients. 605 DEPs between 6d-VS-3d, 1188 DEPs between 9d-VS-3d, and 428 DEPs between 9d-VS-6d were obtained, respectively. Conclusion This work provided scientific basis to study protein profile and comparison of protein expression levels of O. sinensis zjut, and it will be helpful for metabolic engineering works to active ingredients for exploration, application and improvement of this fungus.

Plane Wave Reflection in a Compressible Half Space with Initial Stress

In this paper, the problem of wave propagation in a compressible half-space with an initial stress is considered. General discussion on the speed of wave in the presence of an initial stress is presented. Furthermore, reflection of a homogeneous plane P−wave is also studied. A special strain energy function dependent on this initial stress is used to understand the response of the materials. Explicit formulas for the reflection coefficients are also presented. General nonlinear theory and the theory of invariants are used to derive theoretical results. Graphical illustration of theoretical results for various numerical values of parameters show that initial stress has considerable bearing on the behavior of a plane wave.

Influence of Rheological Properties of a Soil Layer Adjacent to the Working Body Cutting Element on the Mechanism of Soil Cultivation

On the basis of rheological characteristics, stress fields and deformations, new methods of improving the mechanism of soil cultivation are substantiated in this article. The mechanism of soil destruction is observed. Paper investigates the process of changing the stressed-deformed state of the soil under the influence of the working body. To study the viscoelastic properties of black earth soil, the method of amplitude sweeping with a measuring system of parallel high planes was applied using a modular rheometer MCR-302 (Anton Paar, Austria). Range of linear viscoelasticity of virgin soil was found to reach 0.1% deformation; range of linear viscoelasticity of cultivated field area is smaller by an order of magnitude – to 0.02% deformation. Structure destruction (the point of equality of modules) of virgin soil occurs at 20% deformation; structure of long steam soil destructs at 8% deformation. Technique of measuring the isobar zones distribution in horizontal and vertical planes by means of special strain gauges of the LPX 5000 model was developed. To reproduce the force pattern of the working bodies’ effect on soil environment, the measuring complex MIC 400D is used; stress-strain state of the soil is defined.

Antimutagenic Activity of Ethanolic Extract of Roccella montagnei Against Sodium Azide – An In Vitro Study

Lichens are considered to be a potential source of active molecules as they produce a variety of secondary metabolites in response to environmental stress conditions. The present work was aimed at evaluating the possible mutagenic and antimutagenic activities of the ethanolic extract of Roccella montagnei (EERM) against a potent mutagen, sodium azide (NaN3). Ames test was performed using Salmonella typhimurium TA100 (MTCC Acc. No. 1252), a special strain designed to detect base-pair substitution. The extract was screened for its antimutagenic activity at three concentrations (5.0, 10.0 and 20.0 μg/plate dissolved in 10% DMSO) against NaN3 (1.0 μg/plate) in the absence and presence of mouse S9 fraction. The numbers of histidine revertant colonies (CFU/ plate) were counted. Each experiment was conducted in triplicates and statistical analysis was done. The rate of antimutagenicity was determined using the formula [(M-S1)/(M-S0)]×100. The observed data confirmed the mutagenic potency of NaN3 both in the absence (412.7±35.6) and presence of S9 fraction (569.5±41.3), which were found to be statistically significant compared to the solvent control (p less than 0.001). There was no significant increase in the number of revertants indicating that EERM did not induce base pair substation in the test organism. EERM imparted the antimutagenic effect at the moderate level against NaN3 after its metabolic activation as indicated by decrease in the number of revertants (38.7%; pless than 0.01). However, the antimutagenic potency of EERM was found to be weak against NaN3 without S9 fraction (22.0%). Thus, the ethanolic extract of R. montagnei, to some extent, protects against NaN3-induced mutation after its metabolic activation.

A computational approach to estimating nondisjunction frequency in Saccharomyces cerevisiae

Errors segregating homologous chromosomes during meiosis result in the formation of aneuploid gametes and are the largest contributing factor to birth defects and spontaneous abortions in humans. Saccharomyces cerevisiae has long served as a model organism for studying the gene network supporting normal chromosome segregation. Current methods of measuring homolog nondisjunction frequencies are laborious and involve dissecting thousands of tetrads to detect missegregation of individually marked chromosomes. Here we describe a holistic computational approach to determine the relative contributions of meiosis I nondisjunction and random spore death in mutants with reduced spore viability. These values are based on best-fit distributions of 4, 3, 2, 1, and 0 viable-spore tetrads to observed distributions in mutant and wild-type strains. We show proof-of-principle using published data sets that the calculated average meiosis I nondisjunction frequency closely matches empirically determined values. This analysis also points to meiosis I nondisjunction as an intrinsic component of spore inviability in wild-type strains. We uncover two classes of mutants that show distinct relationships between nondisjunction death and random spore death. Class I mutants, including those with known defects in establishing and maintaining the physical engagement of homologous chromosomes display a 4-fold greater ratio of nondisjunction death to random spore death compared to Class II mutants, which include those with defects in sister chromatid cohesion. Low numbers of required tetrads facilitates epistasis analysis to probe genetic interactions. Finally the application of the R-Scripts does not require any special strain construction and can be applied to previously observed tetrad distributions.

Construction of the Starter to Produce Lignocellulases via Solid State Fermentation of Rice Straw

The study demonstrates the starter construction and its solid state fermentation (SSF) using rice straw as substrate for lignocellulases production. The starter is constructed by natural microflora growing on rice straw additionally reinforced with Aspergillus niger ZJU-RYD1, using the SSF substrate rice straw with 90% moisture content, successfully produced the integrate and high active lignocellulases at about 72 h, i.e. CMCase 12.44 U/g, cellobiase 12.05 U/g, FPAase 3.18 U/g, xylanase 365.61 U/g, lassase 2.48 U/g. In this study the strategy is satisfactorily developed to construct the starter for high effective and low-cost production of lignocellulases using rice straw as substrate, based on natural microflora and additional reinforcing with special strain.

Construction of the Starter to Produce Lignocellulases via Solid State Fermentation of Metropolis Lignocellulosic Waste Defoliation

The study demonstrates the starter construction and its solid state fermentation (SSF) using metropolis lignocellulosic waste defoliation supplemented with wheat bran as substrates for lignocellulases production. The starter is constructed by natural microflora growing on defoliation additionally reinforced with Aspergillus niger ZJU-RYD1, using the SSF substrate defoliation with 90% moisture content, successfully produced the integrate and high active lignocellulases at about 120 h, i.e. CMCase 8.58 U/g, cellobiase 10.97 U/g, FPAase 2.21 U/g, xylanase 446.25 U/g, lassase 9.21U/g. In this study, the strategy is satisfactorily developed to construct the starter for high effective and low-cost production of lignocellulases using metropolis lignocellulosic waste defoliation as substrate, based on natural microflora and additional reinforcing with special strain