Effect of plant seeds protein extract on the Sunn pest, Eurygaste integriceps Puton, growth and development and its gut serine protease activity

The sunn pest Eurygaster integriceps Puton (Hemiptera: Scutelleridae) is a major pest of wheat and barley in wide areas of the world that cause 100% crop loss when no control measures are taken. The aim of this study was to investigate the effect of the seed proteinous extract of different plant species including Chickpea Cicer arietinum (Fabaceae), bean Phaseolus vulgaris var. naz (Fabaceae), triticale Triticosecale wittmack (Poaceae), Celosia argentea (Amaranthaceae) in artificial diet against the Sunn pest growth and development as well as gut serine proteinase such as trypsin and chymotrypsin activities. The obtained results showed that protease inhibitors present in the seed extract affected nymphal development, adult weight and survivability to some extent. Mean developmental time of third and fourth instar nymphs were not significantly affected by the presence of seed extracts. However, developmental time of the fifth instar nymph was affected by seeds proteinous extracts. Bean proteinous extract increased developmental time significantly by almost two days followed by Chickpea that increased developmental time by one day (P < 0.01). Amaranthus seed proteinous extract caused slight increase in development time. Triticale extract did not affect nymph growth and development and there were no significant differences between developmental time of triticale extract and control. Azocaseinolytic activity of gut extract of E. integriceps was affected greatly by seed proteinous extracts. There were significant differences in general protease activity between control and all treatments. General protease activity dropped significantly low when treated with bean and cowpea extracts (P< 0.01). Almost the same trend was observed when trypsin and chymotrypsin activities were measured using BApNA and SAAPFpNA as substrates, respectively. It is concluded that seed extracts from non host plants of the Sunn pest caused significant reduction of general and specific protease activity in vitro.Key words: Sunn pest, growth, development, seed extracts, protease activity

Comparision of Density Measurement Methods for Unidirectional Flax-Epoxy Polymer Composites

Density is a decisive factor in determining one of the most important advantages of flax fiber-reinforced polymer (FFRP) composites, i.e. their relatively low weight leading to high specific properties. As a fundamental physical property of composites, density enters in many engineering design and quality control calculations and its value is a determining factor for several applications. Especially, we need precise material properties including density so as to develop efficient numerical models to these materials. In this work, three density measurement methods were evaluated and compared: Helium-gas pycnometry and Archimedes with two different immersing liquids, water and ethanol. The results show that Helium-gas pycnometry and Archimedes with ethanol gave similar and repeatable results, whereas using water resulted in much lower values. The density values were all in the range of reported values. However, Helium-gas pycnometry or Archimedes using ethanol are recommended for more precision in measuring the density of FFRP composites

Comparision of density measurement methods for unidirectional flax-epoxy polymer composites

Density is a decisive factor in determining one of the most important advantages of flax fiber-reinforced polymer (FFRP) composites, i.e. their relatively low weight leading to high specific properties. As a fundamental physical property of composites, density enters in many engineering design and quality control calculations and its value is a determining factor for several applications. Especially, we need precise material properties including density so as to develop efficient numerical models to these materials. In this work, three density measurement methods were evaluated and compared: Helium-gas pycnometry and Archimedes with two different immersing liquids, water and ethanol. The results show that Helium-gas pycnometry and Archimedes with ethanol gave similar and repeatable results, whereas using water resulted in much lower values. The density values were all in the range of reported values. However, Helium-gas pycnometry or Archimedes using ethanol are recommended for more precision in measuring the density of FFRP composites

A Study of the interlaminar fracture toughness of unidirectional flax/epoxy composites

Having environmental and economic advantages, flax fibers have been recognized as a potential replacement for glass fibers as reinforcement in epoxy composites for various applications. Its widening applications require employing failure criteria and analysis methods for engineering design, analysis, and optimization of this material. Among different failure modes, delamination is known as one of the earliest ones in laminated composites and needs to be studied in detail. However, the delamination characteristics of unidirectional (UD) flax/epoxy composites in pure Mode I has rarely been addressed, while Mode II and Mixed-mode I/II have never been addressed before. This work studies and evaluates the interlaminar fracture toughness and delamination behavior of UD flax/epoxy composite under Mode I, Mode II, and Mixed-mode I/II loading. The composites were tested following corresponding ASTM standards and fulfilled all the requirements. The interlaminar fracture toughness of the composite were determined and validated based on the specific characteristics of natural fibers. Considering the variation in the composite structure configuration and its effects, the results of interlaminar fracture toughness fit in the range of those reported for similar composites in the literature and provide a basis for the material properties of this composite