Study of Totipotency in the Leaf Cells of the Carrot Plant

Studies of the totipotency of cells of various parts of carrot tissues and organ formation by the cultivated carrot leaf cells have been made in this investigation. It is believed that each matured cell, even though appearances differ from cell to cell, still contains the whole set of genes as in a zygote. The differences in appearance are due to the functional genes. This potential of the matured cells to go back to the zygote state is called totipotency. Theoretically, if certain stimuli were applied to force these nonfunctional genes to become functional, all these cells may behave in the same way as the zygote. F.C. Steward has studied the totipotency of the carrot root (34, 35, 36, 37, 38, 39). He started by cultivating a piece of carrot root tissue in media containing small plant stimuli. He found that the tissue develops through several different stages and ends with an entire carrot plant, indicating that the cells in the carrot root tissues have totipotency. Plant tissue culture was introduced by Haberlandt in 1902. Within the plant kingdom, both gymnosperms and angiosperms have been used for tissue culture. Not all plants are easily cultivated. There have been attempts to cultivate many parts of plant tissues from different plants. All these cultures can either maintain the metabolic activity in the media and enlarge cells or regain the dividing activity and form callus tissues. The cultivating media usually contains three major components; carbohydrate, minerals and organic supplements. (see more in text

Constant-temperature molecular-dynamics algorithms for mixed hard-core/continuous potentials

We present a set of second-order, time-reversible algorithms for the isothermal (NVT) molecular-dynamics (MD) simulation of systems with mixed hard-core/continuous potentials. The methods are generated by combining real-time Nose' thermostats with our previously developed Collision Verlet algorithm [Mol. Phys. 98, 309 (1999)] for constant energy MD simulation of such systems. In all we present 5 methods, one based on the Nose'-Hoover [Phys. Rev. A 31, 1695 (1985)] equations of motion and four based on the Nose'-Poincare' [J.Comp.Phys., 151 114 (1999)] real-time formulation of Nose' dynamics. The methods are tested using a system of hard spheres with attractive tails and all correctly reproduce a canonical distribution of instantaneous temperature. The Nose'-Hoover based method and two of the Nose'-Poincare' methods are shown to have good energy conservation in long simulations.Comment: 9 pages, 5 figure

The Structure on Invariant Measures of C1C^1 generic diffeomorphisms

Let $\Lambda$ be an isolated non-trival transitive set of a $C^1$ generic diffeomorphism f\in\Diff(M). We show that the space of invariant measures supported on $\Lambda$ coincides with the space of accumulation measures of time averages on one orbit. Moreover, the set of points having this property is residual in $\Lambda$ (which implies the set of irregular$^+$ points is also residual in $\Lambda$). As an application, we show that the non-uniform hyperbolicity of irregular$^+$ points in $\Lambda$ with totally 0 measure (resp., the non-uniform hyperbolicity of a generic subset in $\Lambda$) determines the uniform hyperbolicity of $\Lambda$

Prediction of superhard carbon allotropes from the segment combination method

Many superhard allotropes of carbon have been proposed in recent years for the purpose of explaining the superhard carbon phases observed in the processes of cold compressing graphite and carbon nanotubes. In this paper, we have reviewed recent advances in searching for superhard phases of carbon from a segment combination view and found that they can be divided into two groups: (i) combinations of segments from cubic diamond and hexagonal diamond with 5-6-7 carbon rings and (ii) combinations of segments from hexagonal diamond and mutated hexagonal diamond with 4-6-8 carbon rings. Finally, an additional example of extending these allotropes of carbon to their corresponding boron nitride counterparts has been discussed.В останні роки було запропоновано безліч надтвердих алотропів вуглецю для пояснення його надтвердих фаз, які спостерігають в процесах холодного стиснення графіту і вуглецевих нанотрубок. У даній статті розглянуто останні досягнення в пошуках надтвердих фаз вуглецю з погляду методу комбінації структурних сегментів і виявлено, що вони можуть бути розділені на дві групи: 1) сполучення сегментів кубічного алмазу і гексагонального алмазу з 5-6-7-членними кільцями вуглецю і 2) сполучення сегментів гексагонального і мутованого гексагонального алмазу з 4-6-8-членними вуглецевими кільцями. Нарешті, розглядається відповідність алотропів вуглецю можливим структурам нітриду бору.В последние годы было предложены много сверхтвердых аллотропов углерода для объяснения его сверхтвердых фаз, наблюдаемых в процессах холодного сжатия графита и углеродных нанотрубок. В данной статье рассмотрены последние достижения в поиске сверхтвердых фаз углерода с точки зрения метода комбинации структурных сегментов и обнаружено, что они могут быть разделены на две группы: 1) сочетания сегментов кубического и гексагонального алмаза с 5-6-7-членными кольцами углерода и 2) сочетания сегментов гексагонального и мутированного гексагональног

Ultrasonic extraction of flavonoids and phenolics from loquat (Eriobotrya japonica Lindl.) flowers

Ethanol was used to extract flavonoids and phenolics from loquat (Eriobotrya japonica Lindl. cv. Ruantiaobaisha) flowers with ultrasonic pharmaceutical managing machine. Single-factor and orthogonal experiment were used to investigate the optimum extraction condition. The results showed that, the combination of 30°C, 80 min, 60% ethanol and 1:40 material ratio was optimum extraction condition with the highest yields of flavonoids and phenolics at 47 kHz/500 W. Under the optimum extraction condition, two consecutive extractions was enough, the extraction rates of flavonoids and phenolics were all more than 90%, with the contents of 10.59 and 102.02 mg/g dry weight, respectively.Key words: Eriobotrya japonica, flower, flavonoids, phenolics, ultrasonic extraction