Thirty-six lots of eightCuphea species grown at nine geographical locations from 1983 to 1985 were analyzed for seed weight, oil percentage, fatty acid
and crude protein content. Twenty-two samples were separated into two distinct seed maturity groups and also analyzed. Seed
maturity varied widely but had little effect on oil percentage, even though mature seeds were significantly heavier than less
mature seeds. Lauric acid content generally increased and capric acid decreased with increasing seed maturity. Crude protein
of whole seeds and defatted seed meal increased with increasing seed maturity. The net effect of harvestingCuphea wrightii seeds at full maturity in comparison with that for less mature seeds was to increase seed weight by 12%, decrease capric
acid by 3%, increase lauric acid by 2% and increase crude protein of whole seeds and defatted meal by 5% and 4%, respectively.
Seed oil content was decreased by a statistically nonsignificant 1%. The effect of seed maturity was comparable for the other
four lauric acid- and three capric acid-rich species, even though distinct species differences in all factors were measured.
Location and environment contributed to some quantitative and qualitative changes, but these factors are not considered to
be major sources of variation. It is concluded that variation in seed maturity does not present a major constraint to commercialization
ofCuphea as a new, alternative source of lauric and other medium-chain fatty acids. The ultimate significance of these minor changes
will depend upon relative yields, demands and values of the various seed components. 相似文献
Male, female and castrated rats, three wk of age, were fed a low-fat diet for 14 wk followed by high-fat diets (20% by weight)
for one wk containing graded levels of erucic acid from 1 to 50%, to evaluate the effect of short-term feeding and interaction
of male sex hormones on formation of heart lesions. Some rats within each group were returned to the low-fat diet for one
wk after the test period. For comparison, one group of three-wk-old male rats was fed the high fat 50% erucic acid diet for
15 wk. Erucic acid depressed growth rate and food consumption and increased cardiac lipidosis and triglycerides proportional
to the erucic acid content of the diet. There were no sex differences, and the effects disappeared once rats were returned
to the low-fat diet for one week. There was a significance (P<0.05) in the incidence of myocardial necrosis among male rats
fed increased levels of erucic acid for one week, but the response was not linear to the increase in dietary erucic acid.
Furthermore, the response was much less than in males fed the 50% erucic acid diet continually for 15 weeks. These results
suggest that the short-term model is not a suitable substitute for the long-term feeding trial to test the cardiopathogenicity
of a vegetable oil. The significantly lower incidence in myocardial lesions in female and castrated male rats compared with
male rats suggests involvement of sex hormones. However, the process appears to be long term, since changes in cardiac lipids
and their fatty acid pattern between sexes became evident after one wk on diet but was significant only after long-term feeding.
Deceased. 相似文献
The precision and accuracy of the Iatroscan method was evaluated by comparing the results obtained with established phosphorus
and gas chromatographic techniques. A complete lipid class analysis of rat heart lipids was chosen in order to evaluate the
performance of the Iatroscan method for biological samples which contained both neutral lipids and phospholipids. A partial
scan and repeat development with chloroform/methanol/water (68.5∶29∶2.5) was introduced to achieve consistently good separations
of the phospholipids on the Chromarods in the Iatroscan method. The results showed that the precision of the Iatroscan method
for some lipid classes was comparable to that of phosphorus or gas chromatographic techniques, while for other lipid classes
it was lower. Compared to the data obtained using the phosphorus method, the Iatroscan data were generally similar, while
the gas chromatographic method generally gave lower values. These findings, together with the advantages of time required
for analysis, size of sample, and universality of detection, suggest that the Iatroscan is a valuable complementary method
for complex lipid analyses. 相似文献
The effect of copper content (0.01 and 2.1%) and microstructure on the intrinsic hydrogen embrittlement susceptibility of unl nercially-processed AI---6Zn---2Mg---XCu alloys was investigated. (The alloy with 2.1 Cu corresponds to 7059). Hydrogen was introduced into the alloys using cathodic charging, both with and without concurrent plastic straining. The copper-free alloy in both the under-aged and peak-aged conditions was embrittled by hydrogen and the effect was enhanced by concurrent plastic strain. The copper-containing alloy (7050) was susceptible to hydrogen embrittlement when under-aged, but once the peak-strength microstructure had been developed, the alloy in the longitudinal direction showed no embrittlement even under severe hydrogen-entry conditions. Similar beneficial effects have been reported for copper additions in imparting resistance to humid air and stress-corrosion cracking for high strength AI-Zn-Mg alloys, and the results are discussed with emphasis on the parallel nature of the phenomena of stress-corrosion cracking and hydrogen embrittlement. 相似文献
Single channel currents were activated by GABA (0.5 to 5 microM) in cell-attached and inside-out patches from cells in the dentate gyrus of rat hippocampal slices. The currents reversed at the chloride equilibrium potential and were blocked by bicuculline (100 microM). Several different kinds of channel were seen: high conductance and low conductance, rectifying and "nonrectifying." Channels had multiple conductance states. The open probability (Po) of channels was greater at depolarized than at hyperpolarized potentials and the relationship between Po and potential could be fitted with a Boltzmann equation with equivalent valency (z) of 1. The combination of outward rectification and potential-dependent open probability gave very little chloride current at hyperpolarized potentials but steeply increasing current with depolarization, useful properties for a tonic inhibitory mechanism. 相似文献
We describe control of the polarization state of a diode-pumped Nd:YAG laser that is Q switched with an acousto-optic modulator (AOM). One of two orthogonal linear polarization states can be made dominant, depending on the amount of loss introduced by the AOM. Heterodyne beating indicates that the two polarization states are of slightly different frequencies. 相似文献
In recent years, we face an increasing interest in protecting multimedia data and copyrights due to the high exchange of information. Attackers are trying to get confidential information from various sources, which brings the importance of securing the data. Many researchers implemented techniques to hide secret information to maintain the integrity and privacy of data. In order to protect confidential data, histogram-based reversible data hiding with other cryptographic algorithms are widely used. Therefore, in the proposed work, a robust method for securing digital video is suggested. We implemented histogram bit shifting based reversible data hiding by embedding the encrypted watermark in featured video frames. Histogram bit shifting is used for hiding highly secured watermarks so that security for the watermark symbol is also being achieved. The novelty of the work is that only based on the quality threshold a few unique frames are selected, which holds the encrypted watermark symbol. The optimal value for this threshold is obtained using the Firefly Algorithm. The proposed method is capable of hiding high-capacity data in the video signal. The experimental result shows the higher capacity and video quality compared to other reversible data hiding techniques. The recovered watermark provides better identity identification against various attacks. A high value of PSNR and a low value of BER and MSE is reported from the results.
Engineers are often expected to span organizational, cultural, stakeholder, geographic, temporal, and other boundaries. Yet, few studies on boundary spanning have appeared in the engineering education literature, suggesting the need for improved theoretical and conceptual foundations to guide empirical studies of boundary spanning in engineering.
Purpose
To develop a more comprehensive understanding of boundary spanning, this study addresses five research questions: (a) What types of boundaries have been identified as topics of interest? (b) How are boundary spanners and boundary spanning defined? (c) What types of activities and behaviors comprise or have been linked to boundary spanning? (d) What individual competencies and characteristics have been proposed or studied as important for boundary spanning? and (e) What boundary spanning themes are most prominent in studies of engineers and other technical professionals?
Scope/Method
Using a qualitative systematic review process, we identified and analyzed 72 scholarly papers from multiple disciplines. Multiple reviewers coded each paper using a hybrid deductive‐inductive content analysis process to identify key themes related to boundary spanning.
Conclusions
The analysis resulted in a framework consisting of six boundary types, three types of roles and definitions, and five types of activities. Discussion of boundary spanning competencies was limited in the collected works, and only seven papers exclusively focused on engineers. We conclude by proposing boundary spanning as an important meta‐attribute for engineers and a promising lens for investigating engineering practice. We also relate our findings to the engineering education literature and suggest directions for future research. 相似文献
In this paper we discuss the various models that have been used to predict whether a material will tend to be ductile or brittle. The most widely used is the Pugh ratio, , but we also examine the Cauchy pressure as defined by Pettifor, a combined criterion proposed by Niu, the Rice and Thomson model, the Rice model, and the Zhou-Carlsson-Thomson model. We argue that no simple model that works on the basis of simple relations of bulk polycrystalline properties can represent the failure mode of different materials, particularly where geometric effects occur, such as small sample sizes. Instead the processes of flow and fracture must be considered in detail for each material structure, in particular the effects of crystal structure on these processes. 相似文献
Horizontal standard lamps calibrate the spectral irradiance responsivity of spectroradiometers that measure solar ultraviolet irradiance. A field calibration unit and power supply developed to meet the requirements for using these standards in the field are described and their operation and associated uncertainties are detailed. Results from assessments obtained at two field instrument intercomparisons indicate that the horizontal standard, field calibration unit, and power supply operate within the design tolerances, making them suitable for performing routine calibrations in the field on most ultraviolet spectroradiometers. 相似文献