A Comparative Study of the Effect of Field Retting Time on the Properties of Hemp Fibres Harvested at Different Growth Stages

In this study, the comparison of field retting of hemp fibres harvested at different growth stages (beginning and end of flowering, seed maturity) was studied. Regardless of the harvest period, identical evolution of the fibres’ properties was observed during retting. The main difference is the kinetics of this transformation, which depend on weather conditions and the initial state of the fibres after harvesting. Retting leads to a change in colour of the stems and fibres, an increase of the cellulose fraction and a gradual improvement of the fibres’ thermal stability, in relation with a decrease in the non-cellulosic materials. This process induces fibre bundle separation into elementary fibres. A long period (5 weeks) is required for getting the highest mechanical properties of fibres harvested at the beginning and the end of flowering. However, the retting of fibres harvested at seed maturity has to be performed in a short period (1 week) in order to avoid over-retting treatment. If the fibres are over-retted, their quality decreases in terms of structure and mechanical properties.

Download Full-text

Structure Features of Martensite and Residual Austenite during Treatment with Concentrated Energy Fluxes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.83-86.889 ◽

2009 ◽

Vol 83-86 ◽

pp. 889-895

Author(s):

Dimitar Stavrev ◽

Tsanka D. Dikova

Keyword(s):

Mechanical Properties ◽

Martensite Transformation ◽

Residual Austenite ◽

Plasma Arc ◽

Low Carbon ◽

Initial State ◽

Temperature Changes ◽

Specific Morphology ◽

Kinetics Of ◽

Martensite Structure

The paper deals with the structure features of Fe-C alloys quenched by means of laser, electron beam and plasma arc. The martensite and residual austenite obtained are highly inhomogeneous. Their morphology and distribution depend both on the initial state before quenching and on the kinetics of the temperature changes. Four different structures of martensite are observed – package, lamellar isothermal, lamellar thermo-kinetic and “feathery nest-like”. The new martensite structure observed, called by us “feathery nest-like”, is a result of explosive austenite-martensite transformation in pearlitic irons. It differs from the classic modification in its specific morphology. Low-carbon package martensite occupies the regions of the former ferrite grains. Its hardness reaches 1050-1150 HV0.1. In the regions of microstructure with increased carbon concentration lamellar martensite is observed. The residual austenite is with different proportion in relation to the martensite. In particular regions its quantity could reach 100%. It is characterized by a high quantity of imperfections and high mechanical properties. Its hardness reaches 450-500 HV0.1. The higher the power density and the lower the energy density of the concentrated energy flux, the higher the residual austenite quantity.

Download Full-text

Kinetics of wound-induced activation of antioxidative enzymes in Oryza sativa: differential activation at different growth stages

Plant Science ◽

10.1016/s0168-9452(03)00078-5 ◽

2003 ◽

Vol 164 (6) ◽

pp. 935-941 ◽

Cited By ~ 16

Author(s):

Hema Kumar Chandru ◽

Eunsun Kim ◽

Yongin Kuk ◽

Kyoungwon Cho ◽

Oksoo Han

Keyword(s):

Oryza Sativa ◽

Antioxidative Enzymes ◽

Growth Stages ◽

Differential Activation ◽

Kinetics Of ◽

Different Growth Stages

Download Full-text

HT-2 and T-2 toxins in Norwegian oat grains related to weather conditions at different growth stages

European Journal of Plant Pathology ◽

10.1007/s10658-017-1394-3 ◽

2018 ◽

Vol 151 (2) ◽

pp. 501-514 ◽

Cited By ~ 5

Author(s):

Anne-Grete Roer Hjelkrem ◽

Heidi Udnes Aamot ◽

Guro Brodal ◽

Einar C. Strand ◽

Torfinn Torp ◽

...

Keyword(s):

Weather Conditions ◽

Growth Stages ◽

Different Growth Stages

Download Full-text

Effect of Deformation Temperature on Microstructure and Mechanical Properties of Low-Alloyed Copper Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.982 ◽

2018 ◽

Vol 941 ◽

pp. 982-987

Author(s):

Anna Morozova ◽

Yana Olkhovikova ◽

Evgeniy Tkachev ◽

Andrey Belyakov ◽

Rustam Kaibyshev

Keyword(s):

Mechanical Properties ◽

Dynamic Recrystallization ◽

Deformation Temperature ◽

Copper Alloy ◽

Elevated Temperatures ◽

Initial State ◽

Continuous Dynamic Recrystallization ◽

Small Strains ◽

Continuous Dynamic ◽

Kinetics Of

The microstructure evolution and mechanical properties of a copper alloy subjected to deformation at temperatures of 20 °C and 400 °C to total strains from 1 to 4 were examined. The formation of planar low-angle boundaries with moderate misorientations occurs within initial grains at relatively small strains regardless of deformation temperature. Upon further processing the misorientations of these boundaries progressively increase and the new ultrafine grains develop. Continuous dynamic recrystallization takes place during deformation at ambient and elevated temperatures. The kinetics of dynamic recrystallization is discussed in terms of a modified Johnson-Mehl-Avrami-Kolmogorov relationship. The large plastic straining results in significant strengthening, the ultimate tensile strength increases from 190 MPa in the initial state to 440 MPa and to 400 MPa after total strain of 4 at 20 °C and 400 °C, respectively. A modified Hall-Petch relationship is applied to evaluate the contribution of grain refinement and dislocation density to the overall strengthening.

Download Full-text

Ruminal fermentation kinetics of nine halophytic tree species at different growth stages

Agroforestry Systems ◽

10.1007/s10457-018-0287-6 ◽

2018 ◽

Vol 93 (5) ◽

pp. 1843-1852

Author(s):

Mostafa Yousef Elahi ◽

Ameer Khusro ◽

Mona M. Y. Elghnadour ◽

Abdelfattah Z. M. Salem ◽

Secundino López

Keyword(s):

Tree Species ◽

Growth Stages ◽

Ruminal Fermentation ◽

Fermentation Kinetics ◽

Kinetics Of ◽

Different Growth Stages

Download Full-text

DON content in oat grains in Norway related to weather conditions at different growth stages

European Journal of Plant Pathology ◽

10.1007/s10658-016-1113-5 ◽

2016 ◽

Vol 148 (3) ◽

pp. 577-594 ◽

Cited By ~ 9

Author(s):

Anne-Grete Roer Hjelkrem ◽

Torfinn Torp ◽

Guro Brodal ◽

Heidi Udnes Aamot ◽

Einar Strand ◽

...

Keyword(s):

Weather Conditions ◽

Growth Stages ◽

Different Growth Stages

Download Full-text

Cytokinins from terminal buds of Euphoria longana during different growth stages

Physiologia Plantarum ◽

10.1034/j.1399-3054.1997.990125.x ◽

1997 ◽

Vol 99 (1) ◽

pp. 185-189

Author(s):

Wen-Shaw Chen ◽

Kuang-Liang Huang ◽

Hsiao-Ching Yu

Keyword(s):

Growth Stages ◽

Terminal Buds ◽

Different Growth Stages

Download Full-text

SCALE INHIBITION OF SODIUM CARBOXYMETHYL CELLULOSE AT DIFFERENT GROWTH STAGES BASED ON MOLECULAR DYNAMICS SIMULATION

Heat Transfer Research ◽

10.1615/heattransres.2020033226 ◽

2020 ◽

Vol 51 (16) ◽

pp. 1455-1464

Author(s):

Yu Zhao ◽

Shanshan He ◽

Zhiming Xu ◽

Bingbing Wang

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Carboxymethyl Cellulose ◽

Dynamics Simulation ◽

Sodium Carboxymethyl Cellulose ◽

Growth Stages ◽

Scale Inhibition ◽

Different Growth Stages

Download Full-text

Basic set of experiments for determination of mechanical properties of sand

Bulletin of the Polish Academy of Sciences Technical Sciences ◽

10.2478/bpasts-2014-0015 ◽

2014 ◽

Vol 62 (1) ◽

pp. 129-137

Author(s):

A. Sawicki ◽

J. Mierczyński

Keyword(s):

Mechanical Properties ◽

Soil Mechanics ◽

Physical And Mechanical Properties ◽

Local Strain ◽

Initial State ◽

Laboratory Equipment ◽

Additional Information ◽

Basic Set ◽

Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

Download Full-text