Wool characters in “half-bred” sheep (Border Leicester Rams x Cheviot Ewes) (With Plate V and five text-figures.)

1933 ◽  
Vol 23 (3) ◽  
pp. 473-484 ◽  
Author(s):  
J. E. Nichols
Keyword(s):  
Fibre Length ◽  
Fibre Volume ◽  
Laboratory Examination ◽  
Multiple Factors

SummaryData from the laboratory examination of fleece samples from representative animals of the parental Border Leicester and Cheviot stock, the F1 “half-breds” and the F2 ewes, are submitted.The characters of mean fibre length, fineness and mean fibre volume are discussed, the variability found in the various types being particularly noted. The distributions of fibre lengths are also considered, it being found that all the parental forms also appear in the succeeding generations.Evidence of blending inheritance is not manifest in the results, which support the interpretation of multiple factors as responsible for the expression of the wool characters of length and fineness.Attention is called to the importance of considering fibre volumes as criteria of follicle activity.

scholarly journals THE CAPILLARY PATTERN IN HUMAN MASSETER MUSCLE DURING AGEING

2013 ◽  
Vol 32 (3) ◽  
pp. 135 ◽  
Author(s):  
Erika Cvetko ◽  
Jiří Janáček ◽  
Lucie Kubínová ◽  
Ida Eržen
Keyword(s):  
Muscle Fibre ◽  
Masseter Muscle ◽  
3D Visualization ◽  
Fibre Length ◽  
Fibre Surface ◽  
Fibre Volume ◽  
Immunohistochemical Method ◽  
Muscle Fibres ◽  
Age Related ◽  
Novel Approach

The effect of ageing on the capillary network in skeletal muscles has produced conflicting results in both, human and animals studies. Some of the inconsistencies are due to non-comparable and biased methods that were applied on thin transversal sections, especially in muscles with complicated morphological structures, such as in human masseter muscle. We present a new immunohistochemical method for staining capillaries and muscle fibres in 100 µm thick sections as well as novel approach to 3D visualization of capillaries and muscle fibres. Applying confocal microscopy and virtual 3D stereological grids, or tracing capillaries in virtual reality, length of capillaries within a muscle volume or length of capillaries adjacent to muscle fibre per fibre length, fibre surface or fibre volume were evaluated in masseter muscle of young and old subjects by an unbiased approach. Our findings show that anatomic capillarity is well maintained in masseter muscle in old subjects; however, vascular remodelling occurs with age, which could be a response to changed muscle function and age-related muscle fibre type transformations.

Follicular determinants of the length and diameter of wool fibres. 2. Comparison of sheep differing in thyroid hormone status

1994 ◽  
Vol 45 (6) ◽  
pp. 1149 ◽  
Author(s):  
PI Hynd
Keyword(s):  
Thyroid Hormone ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Fibre Volume ◽  
Concomitant Change ◽  
Wool Growth ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Hormone Status ◽  
Dividing Cells

The thyroid hormone status of Corriedale sheep was manipulated in order to produce a change in the rate of fibre elongation (L) with no concomitant change in the diameter (D) of the fibres, to allow the follicular factors responsible for fibre L to be determined. Thyroidectomy resulted in a 60% decrease in wool growth per unit area of skin and a 40% decrease in the rate of fibre volume output, due largely to a decline in fibre L from 412 ,8m/day to 277 8m/day ( P < 0.0001) while fibre D was unchanged (23.9 8m v. 21.9 pm, P > 0-05). Elevation of plasma thyroxine levels to 250% of Control values had no significant effect on fibre L and D, but patch wool growth was increased ( P < 0.05). A high proportion (22.9%) of the follicles in the hypothyroid sheep was inactive in comparison to the low levels of inactivity in the control (1.2%) and hyperthyroid animals (0.1%). The rate of division of follicle bulb cells was depressed by hypothyroidism and increased by hyperthyroidism (P < 0.0001), but there was no effect of thyroid status on the size of the cortical cells released from the wool fibres. Hypothyroid sheep had slightly smaller follicle bulbs and dermal papillae than the control and hyperthyroid animals. The proportion of dividing cells entering the fibre cortex (estimated from cortical cell volume, rate of fibre volume growth and rate of cell division) was depressed by thyroidectomy suggesting that relatively more dividing cells entered the inner root sheath in the follicles of hypothyroid sheep. This is supported by the lower production ratio (ratio of area of fibre to area of fibre-plus-inner root sheath) of the hypothyroid sheep. It is concluded that the rate of fibre elongation is depressed in hypothyroid sheep as a result of both a reduction in the rate of division of cells in the follicle bulb and fewer of these dividing cells entering the fibre cortex. This mechanism allows rapid changes in the rate of fibre elongation to occur with little change in the size of the follicle bulb, and may account for a number of scenarios in which fibre length changes rapidly with no concomitant change in fibre diameter. Fibre diameter, on the other hand, appears to be closely related to the dimensions of the follicle bulb, and by association, to the rate of bulb cell production. Selection of sheep with small follicle bulbs and at the same time, high production ratios, may be means of increasing fibre length whilst maintaining low fibre diameter.

A study of the characteristics of wool follicle and fibre in Merino sheep genetically different in wool production

1987 ◽  
Vol 38 (4) ◽  
pp. 743 ◽  
Author(s):  
AJ Williams ◽  
RJ Winston
Keyword(s):  
Fibre Length ◽  
Average Diameter ◽  
Skin Surface ◽  
Fibre Volume ◽  
Cortical Cells ◽  
Rate Of Increase ◽  
Quality Diet ◽  
Nutritional Level ◽  
The Difference ◽  
Fleece Weight

Fourteen Merino ewes from each of two flocks, selectively bred for either high (Fleece Plus) or low (Fleece Minus) clean fleece weight per head, were randomly allotted to two feeding levels (17 v. 34 g kg-1 liveweight) of a good quality diet and offered these levels for 100 days. During the final 42 days, the rate of wool growth and its components were measured in each sheep. The Fleece Plus sheep had a greater density of wool follicles and produced more wool per unit area of skin. The latter trait interacted with the nutritional level; Fleece Plus sheep were more responsive to the higher nutritional level (45 v. 13%). Both the rate of growth of fibre length and the diameters of fibres produced in secondary follicles were the components associated with this interaction. The sulfur content of the wool was 12% less in wool from Fleece Plus ewes, but the difference between the two flocks was unrelated to the nutritional level. The average diameter (c. 83 8m) of the bulbs of the follicles did not differ between flocks or dietary levels, but follicles in the skin of Fleece Plus sheep were deeper (P < 0.05) below the skin surface (1.52 v. 1.38 mm). Despite the similar maximum bulb diameters, random longitudinal sections of follicles from Fleece Plus sheep had a 10% greater area of mitotically active tissue (P < 0.05). The difference was independent of nutritional level. When colchicine (10 8g) was injected intradermally, the number of cells revealing metaphase arrest within the mitotically active area of the follicle increased linearly with time to 6 h after the injection. The rate of increase in these cells expressed per unit volume of bulb tissue was not however influenced by either genotype or nutritional level. The average volume of cortical cells isolated from the fibres did not differ between genotypes or nutritional levels, but as with fibre volume, the volume of the cortical cells of the Fleece Plus sheep was more sensitive to a change in nutritional level (interaction: P < 0.05). Calculation of the rate of incorporation of cortical cells into fibre from both rate of production of fibre and the size of the cortical cells indicated that 20% more cells were incorporated by the Fleece Plus sheep and 17% more cells were incorporated by those sheep offered the greater dietary allowance. There was no significant interaction between genotypes and nutritional level for this trait.

EMI Shielding Effectiveness of Copper/Epoxy Composites

2005 ◽  
Vol 13 (7) ◽  
pp. 657-668 ◽  
Author(s):  
Robert C. Wetherhold ◽  
Joseph M. McManaman
Keyword(s):  
Volume Fraction ◽  
Surface Condition ◽  
Fibre Volume Fraction ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Fibre Volume ◽  
Shielding Effectiveness ◽  
Emi Shielding Effectiveness ◽  
Ni Powder ◽  
Phase Interference

Samples of shaped and treated copper (Cu) fibre/brittle matrix composites have been fabricated with a variety of fibre shapes, treatments, diameters, and powder inclusions and tested for shielding effectiveness (SE) using the ASTM standard D4935-99 method over the frequency range 200 to 1500 MHz. A small amount of nickel (Ni) powder was included in some specimens to evaluate the effect of magnetic permeability on SE. Most tests were conducted at constant (15 vol%, “v%”) fibre volume fraction. Results show that a smaller fibre diameter results in significant SE improvements. SE was also substantially improved by relatively minor fibre shaping (which changes along the fibre length) or by fine-scale roughening via chemical treatment. Addition of small amounts of Cu powder leads to major improvements in SE. Most of the improvements are presumably due to the establishment of conductive networks, although fibre shaping or treatment allows greater scattering and thus more internal reflections with attendant absorption. The smaller diameter fibres consistently gave better SE. When a continuous fibre mesh was used, high SE resulted, showing the dominance of fibre connectivity for such materials; the surface condition of the mesh is relatively unimportant. The improvements in SE can be achieved with essentially identical mechanical properties, leading to an effective multifunctional material, although most of the SE values achieved so far are modest. Ni powder results in overall improvement in SE as well as a cyclic dependence of SE on frequency, which indicates phase interference at a scale of particle size not previously seen.

Methods of analysis and the influence of fleece characters on unit area wool production of Romney lambs

1960 ◽  
Vol 11 (5) ◽  
pp. 851 ◽  
Author(s):  
AE Henderson ◽  
BI Hayman
Keyword(s):  
Unit Area ◽  
Fibre Length ◽  
Fibre Volume ◽  
Cross Sectional Area ◽  
The Body ◽  
Skin Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Wool Production ◽  
Fibre Number

Investigation has been made of the influence of fibre number per unit area (N), cross-sectional area of fibre (A), and fibre length (L), on wool production per unit area of skin (W). The influence of the compound characters fibre volume (V) and proportion of skin area occupied by fibre (0) has also been considered. Methods are given whereby the significance of the variation associated with any one of these interacting components can be assessed. Data from four groups of lambs were analysed, each group having been subjected to a different nutritional regime. Slightly more than three-quarters of the variation induced in W by these treatments was due to variation in L, with N and A having negligible effects. No evidence was found that the relative influence of the components changed with change in level of production. Differences in W between lambs on the same nutritional level were influenced almost equally by variation in N and L, with A again having a negligible effect. Of the variation in W between positions on lambs, approximately 50 per cent. was accounted for by variation in N, 40 per cent. by variation in A, and 10 per cent. by variation in L. Variation of the compound character O accounted for nearly 90 per cent. of the variation in W over the body.

Impact resistance of short bamboo fibre reinforced polyester concretes

2015 ◽  
Vol 231 (8) ◽  
pp. 683-692 ◽  
Author(s):  
KJ Wong ◽  
KO Low ◽  
HA Israr
Keyword(s):  
Damage Zone ◽  
Impact Resistance ◽  
Fibre Length ◽  
Fibre Volume ◽  
Matrix Cracking ◽  
Scanning Electron Micrographs ◽  
Pull Out ◽  
Bamboo Fibre ◽  
Environment Sustainability ◽  
The Impact

Bamboo fibre is becoming more important as reinforcement in polymer composites owing to its environment sustainability and cost effectiveness. This study examines the performance of bamboo/polyester concretes under impact loading. Specimens at fibre volume fractions of 40 vol.%, 50 vol.% and 60 vol.% and 3 mm, 7 mm and 10 mm fibre lengths were fabricated. Results showed that the optimum impact resistance was attained at 50 vol.%/10 mm, with 16.6 times higher compared to neat polyester. Scanning electron micrographs revealed that the failure mechanisms include matrix cracking, fibre/matrix debonding, fibre pull-out, fibre end damage, fibre splitting and sand particles debonding. In addition, by relating the experimental results to a theoretical model, the damage zone size was found to increase with the fibre length except at 60 vol.%/10 mm, which could be due to fibre–fibre interaction. Results suggest that bamboo fibre is a good candidate to enhance the impact resistance of polyester concrete.

An experimental study on the interdependence of mercerization, moisture absorption and mechanical properties of sustainable Phoenix sp. fibre-reinforced epoxy composites

2018 ◽  
Vol 49 (9) ◽  
pp. 1233-1251 ◽  
Author(s):  
G Rajeshkumar
Keyword(s):  
Mechanical Properties ◽  
Moisture Absorption ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Length ◽  
Fibre Volume ◽  
Epoxy Composites ◽  
Compression Moulding ◽  
Fibre Matrix ◽  
Fibre Reinforced Composites

This paper represents the first effort aimed to study the interdependence of mercerization, moisture absorption and mechanical properties of sustainable Phoenix sp. fibre-reinforced epoxy composites fabricated by compression moulding technique. The investigation was carried out by varying the fibre length (10, 20 and 30 mm), fibre volume fraction (10%, 20%, 30%, 40% and 50%), concentration of sodium hydroxide for fibre treatment (5%, 10% and 15%) and immersion temperature (10℃, 30℃ and 60℃). The fibre–matrix interface and failure mechanism was studied by using scanning electron microscopy. The results revealed that the moisture absorption rate increased with the increase in fibre length, fibre volume fraction and immersion temperature result in loss of tensile and flexural properties. The moisture absorbed samples shows 15% and 7% drop in tensile and flexural strength, respectively. However, this loss was less in mercerized fibre-reinforced composites.

Follicle productivity and wool production in Romney ewes

1962 ◽  
Vol 13 (5) ◽  
pp. 924 ◽  
Author(s):  
DA Ross
Keyword(s):  
Linear Relationship ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Spatial Relationship ◽  
Length Change ◽  
Fibre Volume ◽  
Cross Sectional ◽  
Wool Production ◽  
Absolute Length ◽  
Relationship Of

Fibre diameter and fibre length arrays of monthly samples of 10 mature Romney ewes were each subdivided into seven groups such that group 1 contained the coarsest or longest 15% of fibres and group 7 the finest or shortest 15% of fibres. A study was made of the relation between the characteristics of these seven groups and the level of wool production over a period of 18 months.There was a linear relationship of the form y = a + bx between fibre cross-sectional area d², fibre length per day l , or fibre volume per day d²l (y), and the level of wool production (a), at each of the seven levels within the array. A similar linear relationship held between the change in d², l , or d²l associated with a change in the level of wool production and the corresponding value of d², l, or d²l on which this change was based. In three of the 10 ewes the change in fibre length associated with a change in wool production was constant over the array; in the other ewes the absolute length change increased in the faster-growing fibres. In all ewes the percentage change in d², l , or d²l decreased with increasing fibre size. In four of the five ewes whose wool was free from medullation the change in fibre volume per unit area of fibre cross section associated with a change in the level of wool production was a constant over the array. Some aspects of follicle efficiency and follicle competition are discussed. It is concluded that in mature ewes all follicles have the same "efficiencies" and do not compete for fibre substrate. The spatial relationship of the follicles did not, affect wool production. The concept of a "basic pattern" of wool production is introduced and discussed.

scholarly journals Fibre Bridging and Nozzle Clogging in 3D Printing of Discontinuous Carbon Fibre Reinforced Polymer Composites: Coupled CFD-DEM Modelling

2021 ◽  
Author(s):  
Hao Zhang ◽  
Lixing Zhang ◽  
Haoqi Zhang ◽  
Jiang Wu ◽  
Xizhong An ◽  
...  
Keyword(s):  
3D Printing ◽  
Polymer Matrix ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Length ◽  
Fibre Volume ◽  
Nozzle Clogging ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

Abstract A coupled multiphase model based on computational fluid dynamics (CFD) and discrete element method (DEM) is developed to numerically investigate the extrusion-based 3D printing process of discontinuous carbon fibre reinforced polymer composites. Short carbon fibres are modelled as rigid bodies by clumping discrete spheres in DEM, while polymer matrix is treated as an incompressible Newtonian fluid in CFD. A fluid-particle interaction model is adopted to couple DEM and CFD and represent the dynamic fibre/matrix interaction. Collisions between fibres are considered naturally in DEM by using the Hertz-Mindlin contact law. The coupled CFD-DEM is validated, both qualitatively and quantitatively, against X-ray microtomography (µCT) experimental results for the T300/PA6 composite. Parametric study on various fibre lengths, fibre volume fraction and resin viscosity using the CFD-DEM model shows that the nozzle clogging tends to occur when the fibre length and/or the fibre volume fraction are increased. Use of a polymer matrix with a lower viscosity can be effective to eliminate the clogging issue when printing composites with relatively short fibres. The fibre length is dominating when long fibres are used and the clogging is largely independent on the viscosity of the polymer matrix. Finally, a potential solution of using a cone sleeve insert located above the shrinking region to address the nozzle clogging issue is proposed and numerically assessed.

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