Diosgenin and β-sitosterol were isolated from Solanum xanthocarpum callus, crystallized, and chemically characterized. That these metabolites, particularly diosgenin, form in significant amounts in ...tissue culture may prove useful.
Abstract
Rail vehicles experience problems of hunting and severe wheel/rail wear which result in lower critical speeds. The design of the conventional railway wheelset, consisting of two wheels ...mounted rigidly on an axle, is one of the main factors inhibiting high-speed operation of rail vehicles. In this paper the potential for good dynamic stability at high speeds and improved ride comfort in a rail vehicle equipped with an independently rotating wheelset (IRW) having yaw control are examined. The control for the yaw rotation is provided by a state-variable feedback controller.
Presents a collection of slides covering the following: single-chip NTSC/PAL television; mobile applications; analog television; terrestrial TV; analog TV signaling; TV architecture; direct ...conversion TV-on-a-chip; NTSC/ PAL receiver; low-noise amplifier; mixer; LO harmonics; harmonic rejection filtering; harmonic rejection mixing; LO generation; VSB Nyquist filtering; and digital TV.
1. Each spikelet in Setaria italica Beauv. is borne lateral to a bristle axis as are also the smaller bristles of a bristle shoot to a principal bristle axis. Therefore, the bristle shoot as a whole, ...and not the individual bristle, must be regarded as the morphological and homologous equivalent of a spikelet. 2. Microsporogenesis in this species is normal, and the divisions are of the successive type. The pollen grains are three-celled at shedding. 3. The ovule is anatropous, bitegmic, and crassinucellate. A narrow endostome, formed by the excessive growth of the inner integument, is hooded by part of the outer integument. A pair of nucellar cells abutting the micropyle becomes hypertrophied and richly protoplasmic. 4. A linear tetrad of megaspores is formed, and the innermost is functional. The embryo sac is organized in the usual fashion. Rarely the egg shows conspicuous lateral hooks otherwise found only in synergids. The synergids and the several, multinucleate antipodal cells commence to degenerate before fertilization. 5. The endosperm is of the Nuclear type. After it becomes cellular, the peripheral layer behaves very much like a "cambium." The aleurone layer is single. 6. Double fertilization occurs. The early divisions of the zygote occur in regular sequence but not the later ones. Organ differentiation is like that in other grasses. There is no epiblast. The insertion of the scutellum is at a short distance from the plumule sheath. 7. Only the outer and the inner epidermal layers of the pericarp form the outermost covering of the caryopsis. A nucellar epidermis of empty cells may occasionally persist, although in most cases the nucellar membrane alone survives. The outer integument is completely obliterated, and the inner collapses except toward the tip and in the insertion region near the funicle.
1. The spikelets are one-flowered and have 2 glumes, a lemma, and a palea, two lodicules, three stamens and the ovary. 2. Microsporogenesis is normal and of the successive type. The pollen grains are ...three-celled at shedding. 3. Meiosis in the megaspore mother cell results in a linear tetrad of spores. The embryo sac is of the Polygonum type. An antipodal complex of coenocytic cells is formed. Abnormalities like the formation of an antipodal embryo, supernumerary polar nuclei and twin embryo sacs have been observed. 4. Fertilization and embryogeny have been studied. 5. The endosperm is of the nuclear type. Frequently involutions of the aleurone layer occur at several points on the surface of the endosperm. The involuted aleurone is meristematic. Small islands of starch-filled endosperm cells ensheathed by aleurone are cut off towards the distal end of the kernel. This accounts for 'lobing' of the endosperm. 6. The protective layers of the mature caryopsis consist of the suberised nucellar epidermis forming the perisperm, the insertion region of the inner integument and the pericarp.
