The present investigation was designed to determine the meat nutritional profile of European beaver (Castor fiber L.). The proximate composition, energy value, amino acids composition, chemical scores for indispensable amino acids, fatty acids composition and mineral concentrations were determined. In 100 g of meat the content for moisture ranged from 75.42 to 77.32 g, for protein from 20.21 to 22.33 g, for fat from 0.66 to 2.44 and for ash from 1.12 to 1.24 g. The Nutritional Quality Index for muscle protein was 9. The indispensable amino acids (IAA) at the highest content were lysine and leucine (1.85 and 1.65 g 100 g?1). The average percentage of IAA was 45% and their chemical scores amounted to more than 100. The total percentages of trans-, saturated (SFA), mono, and polyunsaturated (PUFA) fatty acids were 2.25, 32.25, 18.83 and 49.08%. The ratio of PUFA/SFA and n-6/n-3 PUFA were 1.56 and 5.58. The cholesterol content averaged 55.10 mg 100 g?1. The muscle tissue of beavers contained favourable amount of minerals, particularly Fe and heme Fe (64.49 and 45.60 mg kg?1), Zn and Cu (45.07 and 0.98 mg kg?1), as well a low level of Na (461.9 mg kg?1). Summing up, beavers are a valuable nutritional meat source with a desirable chemical composition and a low calorific value and can constitute a healthy alternative food as advantageous for human health and coherent with diet recommendations. 相似文献
The empirical hydrophile-liophile balance (HLB) value of nonionic surfactants is an important parameter used to predict performance
as, e.g., emulsifiers, solubilizers and wetting agents. However, the HLB value is based on an original molecular structure
and does not take into account all the factors affecting the performance of nonionics, such as presence of additives, type
of solvent, temperature, degree of hydration, structural modifications of the surfactant molecule and decomposition of surfactants.
On a performance basis, where these factors come into play, a given nonionic surfactant may exhibit a multiplicity of apparent
HLB values. Accordingly, we recently introduced the term “effective HLB value” which is a performance value which incorporates
into the HLB the parameters listed above. The HLB value thus becomes a variable depending on the physical and chemical conditions
at the time of the measurement. In this work, we investigated the effect of adding glycols and diglycols on the HLB using
3 different methods: cloud point, phenol index and critical micelle concentration (cmc). We found that this type of additive
increases the cloud point, phenol index, cmc and the “effective HLB” of a polyoxyethylated nonionic surfactant. The effectiveness
of the glycols in causing these increases was in the following order; dipropylene glycol > 1,4-butanediol > 1,2-propanediol
> diethylene glycol > ethylene glycol. The solvent effect of glycols and diglycols on the hydrophobic and hydrophilic portions
of the surfactant molecule are discussed. On the hydrocarbon part of the surfactant molecule, the solvents cause a weakening
of the hydrophobic bond and an increase in the cmc. On the polyoxyethylene part of the molecule, the solvent may cause either
an increase or a decrease in the cmc. The effect on the hydro-philic portion is related to hydrogen bonding exhibited by the
additives. The results obtained again suggest that the effective HLB value, which is a measure of the HLB under operative
conditions, may be of greater practical significance than calculated HLB. 相似文献
Thermodynamics is one of the factors which control the orientation distribution of polymer crystals. The present paper deals with crystal orientation in uncrosslinked polymer systems, in which small, isolated crystals are embedded in a viscous matrix. With transient effects neglected, and in the absence of the production of new crystals, orientation is controlled by the orientation-dependent free energy of an anisotropic crystal, F(), and a hydrodynamic potential of the velocity field, Φ (). Example distributions for uniaxially stressed polyethylene are discussed. It has been shown that different mechanisms control crystal orientation depending on the stress difference Δ? = ?33 ? ?11 applied, and the crystal shape factor, ø. At low stresses, Δ? and high assymetry factors, ø, crystal orientation is practically controlled by the hydrodynamic potential. At high stresses and/or low asymmetry ratios it is the strain energy of anisotropic crystals, , which is responsible for orientation distribution. In the intermediate range both mechanisms have to be considered. 相似文献
The purpose of this literature review is to compare different cooling technologies currently in development in research laboratories that are competing to solve the challenge of cooling the next generation of high heat flux computer chips. Today, most development efforts are focused on three technologies: liquid cooling in copper or silicon micro-geometry heat dissipation elements, impingement of liquid jets directly on the silicon surface of the chip, and two-phase flow boiling in copper heat dissipation elements or plates with numerous microchannels. The principal challenge is to dissipate the high heat fluxes (current objective is 300 W/cm2) while maintaining the chip temperature below the targeted temperature of 85°C, while of second importance is how to predict the heat transfer coefficients and pressure drops of the cooling process. In this study, the state of the art of these three technologies from recent experimental articles (since 2003) is analyzed and a comparison of the respective merits and drawbacks of each technology is presented. The conclusion is that two-phase flow boiling in microchannels is the most promising approach; impingement cooling also has good prospects but single-phase liquid cooling is probably only a short-term solution. As an example of the state of the first technology, the Heat and Mass Transfer Laboratory at Ecole Polytechnique Fédérale de Lausanne has already achieved 200 W/cm2 of cooling in a first prototype, with a low pumping power, good temperature uniformity, and at the required maximal operating temperature. 相似文献
Self assembled monolayer field effect transistors (SAMFETs) are reported using a phenylene‐thiophene containing semiconducting mesogen attached through a trichlorosilane anchoring group. Monolayer films, covalently attached to silicon dioxide substrates, form in less than 10 h from solution, thanks to the accelerated reaction of the trichlorosilane anchor. Devices exhibit mobilities as high as 1.7 × 10?2 cm2 V?1 s?1, currents of up to 15 μA (on/off current ratio of 106) with device yields close to unity over large areas for channel lengths up to 100 μm. 相似文献
Structural and Multidisciplinary Optimization - An approximate thickness optimization of a rectangular Kirchhoff-Love plate with variable stiffness under uniform load is performed in this paper.... 相似文献