Analysis of traction‐free assumption in high‐resolution EBSD measurements

The effects of using a traction‐free (plane‐stress) assumption to obtain the full distortion tensor from high‐resolution EBSD measurements are analyzed. Equations are derived which bound the traction‐free error arising from angular misorientation of the sample surface; the error in recovered distortion is shown to be quadratic with respect to that misorientation, and the maximum ‘safe’ angular misorientation is shown to be 2.7 degrees. The effects of localized stress fields on the traction‐free assumption are then examined by a numerical case study, which uses the Boussinesq formalism to model stress fields near a free surface. Except in cases where localized stress field sources occur very close to sample points, the traction‐free assumption appears to be admirably robust.     

Cohesive modeling of dynamic fracture in functionally graded materials

The dynamic fracture of functionally graded materials (FGMs) is modeled using an explicit cohesive volumetric finite element scheme that incorporates spatially varying constitutive and failure properties. The cohesive element response is described by a rate-independent bilinear cohesive failure model between the cohesive traction acting along the cohesive zone and the associated crack opening displacement. A detailed convergence analysis is conducted to quantify the effect of the material gradient on the ability of the numerical scheme to capture elastodynamic wave propagation. To validate the numerical scheme, we simulate dynamic fracture experiments performed on model FGM compact tension specimens made of a polyester resin with varying amounts of plasticizer. The cohesive finite element scheme is then used in a parametric study of mode I dynamic failure of a Ti/TiB FGM, with special emphasis on the effect of the material gradient on the initiation, propagation and arrest of the crack.     

BASIS OF STABILITY OF AMINE SALTS OF LINOLEIC ACID

SUMMARY— The mechanism and generality of the known stabilization against autoxidation conferred on linoleic acid by certain basic amino acids, such as lysine and arginine, was investigated. Basic amino acids were the only class of compounds found to confer the effect. However, the smallest basic amino acid, 2,3-diaminopropionic acid, was not effective, nor was αβω-diaminc acid, 3,6-diaminohexanoic acid, although a simple isomer of lysine. The stabilization was observed only in the solid phase. Inclusion of sodium chloride in the solid matrix was deleterious to the effect. A large number of physical and chemical observations were made and correlated but it has not been possible to draw detailed conclusions about the mechanism of stabilization, nor can a detailed structure of the stabilized complex be suggested. The cause of the phenomenon appears to be closely associated with the physical arrangement of the ions in the crystal lattice.     

Synthesis of 2-N-oleoylamino-octadecane-1,3-diol: a new ceramide highly effective for the treatment of skin and hair

2-N-Oleoylamino-octadecane-1,3-diol is a new synthetic ceramide. The process enables a four-step preparation of 2-amino-octadecane-1,3-diol (D,L-erythro/threo) and a five-step synthesis of 2-N-oleoylamino-octadecane-1,3-diol (D,L-erythro/threo). The latter compound is related to ceramide 2 according to the classification of Downing. This route of synthesis is rapid, reproducible and uses low-cost starting materials. The new ceramide was analysed as follows: ¹H, ¹³C, ¹⁵N NMR spectra afforded an unambiguous characterization of the structure; additionally, these three methods identified the threo and erythro isomers. ¹H and ¹³C NMR permitted the measurement of the threo/erythro ratio (26.6/73.4 and 25.5/74.5, respectively). Chemical ionization mass spectrometry confirmed the expected mass of the pseudo-molecular ion (m/z= 566.5: [M + H]⁺) as well as the presence of different chain lengths other than the oleic moiety due to the fatty acid composition of the technical grade oleic acid used for the synthesis. Capillary gas chromatography measured the threo/erythro ratio (23.5/76.5) which agrees with the ¹H and ¹³C NMR data. Moreover, this method afforded the relative distribution of the different N-acylated chains. The properties of the new synthetic ceramide for the treatment of skin and hair were mainly assessed by two in vitro methods. The first measured the flux of water through lipid-extracted stratum corneum. The described ceramide showed high efficacy in decreasing water loss. The second recorded the friction coefficient of different types of hair: virgin, permanent-waved, and bleached. Treatment by the ceramide led to a strong decrease in this coefficient. This was particularly observed on unrinsed hair. These findings suggest two potential fields of application and beneficial contribution for the new ceramide: repairing the barrier to transepidermal water loss, and improving the surface properties of hair. Synthèse du 2-N-oleoylamino-octadécane-1,3-diol: nouveau céramide à haut potentiel dans le soin de la peau et du cheveu.     

Cooking and Chemical Properties of Raw and Precooked Flaked and Ground Beef Patties Cooked from the Frozen State

Cooking and chemical properties were investigated on beef patties formulated from UDSA Choice or Cutter-Canner cow beef; processed by either grinding, flaking, or flaking, then grinding; and subjected to final broiling from the precooked or raw state. Quality grade of lean exerted minimal influence on the cooking and chemical properties. Precooked patties had more total cooking losses than nonprecooked patties. For precooked patties made from flaked beef, most of the losses in weight; and configuration occurred during precooking rather than final broiling. The opposite was true for precooked patties made from gro and beef. Thus, in order to maximize yield and minimize configurational changes the method of patty processing should be considered in deciding whether to precook patties prior to freezing.     

Fatty Acid Composition of the Inner and Outer Layers of Porcine Backfat as Affected by Energy Level, Sex and Sire

SUMMARY— The effects of energy level, sex and sire upon the fatty acid composition of porcine fackfat were studied in two separate experiments. In both experiments, the inner layer of backfat consistently contained more total saturated fatty acids, primarily accounted for by stearic acid, and contained less palmitoleic, oleic, and linoleic acids than the outer layer. None of the variables in either experiment significantly (P >.0.5) affected the differences between layers.
In Experiment 1, energy levels below 80% of full feed significantly (P < .01) decreased stearic acid content and increased linoleic acid content. In Experiment 2 the fatty acid composition of backfat from pigs fed 80% of full feed did not differ significantly (P > .05) from full-fed pigs.
Backfat from spayed gilts had significantly (P < .01) less linoleic acid than that from boars or barrows, while boars had a significantly (P < .01) higher content of linoleic acid than the other sexes. In Experiment 1, the backfat from barrows contained significantly (P < .01) more stearic acid than that from gilts.
The data from both experiments indicated that sire significantly (P < .01) affected the linoleic acid content of the backfat, while the results of Experiment 2 also showed significant (P < .01) sire effects upon the palmitic, palmitoleic, and stearic acid contents.