Capillary gas liquid chromatography analyses were conducted on free and esterified sterol fractions of cotton (Gossypium hirsutum cv. Stoneville 213) floral buds and anthers. The free sterols of both cotton buds and anthers consist mainly of the common
plant sterols sitosterol, stigmasterol and 24ζ-methylcholest-5-en-3β-ol. The composition of esterified sterols of cotton buds
and anthers were similar, and consisted of pollinastanol, 31-norcycloartanol, cycloartenol, 31-norcycloartenol, 24-dehydropolinastanol
and sitosterol. Desmosterol was also present in both the free and esterified sterols of anthers. The identities of the sterols
were confirmed by gas chromatography-mass spectrometry analyses. Esterified sterols accounted for 46.7 and 88.7% of total
sterols of cotton bud and anthers, respectively. The ratio of esterified sterol to free sterol per gram of tissue is about
8∶1 in anthers. The Δ5-sterols of the esterified sterols of cotton buds and anthers account for only 17 and 9.2% of the total sterols, respectively. 相似文献
In an earlier paper [1], the influence of flow rate, ramp (constant rate of temperature rise) and package density on the rates of dyeing of two basic dyes on Ex/an, and on the levelness obtained in the resulting dyeings, was investigated, and a relationship was derived to link these factors quantitatively. This work has now been extended to cover the behaviour of various basic dyes on Exlan and other acrylic fibres, under conditions expected to give borderline levelness. It has been shown that the shape of the rate–of–dyeing curve depends on the type of acrylic fibre and, to a lesser extent, on the cationic retarder used, but not on dye type within the group of CV2. 5–3. 5 basic dyes examined. The response of dyeing rate and degree of unlevelness to deliberate variations of ramp, as demonstrated in the previous work on Exlan, is now confirmed on Cashmilon. Evidence of a different type of random unlevelness, not related directly to dyeing rate, was also obtained from dyeings on the various fibres at a slow ramp. 相似文献
A new type of mesoporous silica has been prepared which showed 780 m2/g of BET surface area and 0.6 ml/g of primary mesopores narrowly distributed around 4.2 nm. More importantly however, is that it showed short-range zeolite crystallinity as demonstrated by FTIR and XRD analysis, and hydrophobicity as demonstrated by water and n-hexane adsorption.
This material was synthesized via a dual-template, three-step hydrothermal–flocculation–steaming synthesis procedure developed by us recently. Briefly, MFI nanoprecursors (NPs) were first prepared by a low-temperature hydrothermal step using TPAOH as template for zeolite structure, and then flocculated using a surfactant that served as the template for the mesopores. The collected NPs are mesoporous silica exhibiting short-range MFI domains when directly calcined. However, the steaming step promoted the crystallization of the NPs and created uniform mesopores. It was found that almost every detail in these procedures affected the properties of the final product. The most important variables, however, were identified as the duration the flocculants were kept in contact with the liquid phase, and the humidity under which the steaming was conducted. By properly adjusting the procedures, the said mesoporous silica, as well as nanocrystals having high external surface area, could be produced at will. 相似文献
The influence of copper on the morphologies of porous anodic alumina has been investigated under current and voltage control using a sputtering-deposited Al-2.7 at.% Cu alloy and a commercial AA 2024-T3 aluminium alloy anodized in either sulphuric acid electrolyte or the same electrolyte but with addition of tartaric acid. The findings indicate that film development involves repeated formation of embryo cells of anodic alumina at the metal/film interface. During the initial stages of anodizing at constant voltage, cell formation is accompanied by current peaks in the current-time response. The porosity of the resultant films has a lateral aspect due to the layering of embryo cells. The thickness of individual layers is proportional to the formation voltage, with a ratio of the order 1 nm V−1. The cell formation is accompanied by enrichment of copper in the alloy, incorporation of copper species into the anodic film, in low amounts relative to the alloy, and evolution of oxygen. These processes disrupt the formation of the classical pore morphology, characteristic of high purity aluminium, due to continuous formation of fresh embryo cells and re-direction of pores. The main effect of the tartaric acid addition to the sulphuric acid was to reduce the rate of anodizing of the alloys at constant voltage by about 10-20%. 相似文献
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