BA和激素对‘Bonny Best’试管番茄愈伤组织形态发生的影响

用’Bonny Best’番茄品种的子叶和下胚轴作为外植体,在MS附加不同水平和比率的BA和2,4—D(或NAA)或IAA的培养基中,愈伤组织形态发生的情况是不同的。MS+BA4.44μM+2,4-D10μM(子叶),MS+BA0.44-4.44μM+2,4-D1—5μM(下胚轴)使外值体产生淡黄色疏松的愈伤组织,而且生长迅速。若2,4-D浓度低于5μM(子叶)或高于5μM(下胚轴)时,外植体形成白色紧密的愈伤组织,而且生长缓慢,固定2,4-D的浓度,BA浓度由高到低,所形成的愈伤组织的结构由紧密向疏松变化。愈伤组织的液体培养中也出现了类似现象。把愈伤组织转移到生茎培养基中,白色紧密的愈伤组织形成茎较为容易,培养21天后,茎的分化即开始。而疏松的愈伤组织的形态发生则经过了黄色疏松、深褐色胶状到白色紧密的变化。茎的分化出现较晚。愈伤组织培养时生长调节剂的水平对茎的分化有着直接的影响。较高水平的BA(22.2—44.4μM)+NAA10-40μM有利于茎的分化。把子叶和下胚轴切段培养在MS+BA22.2-44.4μM+IAA1-5μM的生茎培养基上,24—60天后,70％以上的外植体正常分化并伸长成茎,生枝率每个切段为3—4个。转移到MS培养基上,形成正常的带根幼苗。把下胚轴切段直接培养在没有激素的MS培养基上,三周后,45.8％的下胚轴形成正常幼苗,出枝率为1.0。把这些幼苗移栽到温室     

Simple high-performance liquid chromatographic method for the determination of medroxyprogesterone acetate in human plasma

The high-performance liquid chromatographic (HPLC) method was developed as a simple, reliable alternative to available methods for measuring plasma concentrations of medroxyprogesterone acetate (MPA). The HPLC method has been successfully automated and is suitable for the rapid, inexpensive analysis of large batches of plasma samples. The best approach involves a solvent extraction followed by HPLC separation and analysis. MPA can be efficiently extracted, at all pH values, by nonpolar solvents. The Spherisorb 5-ODS2 HPLC column provides excellent separation of MPA from endogenous steroids of similar structure and from extraneous plasma blank peaks. A batch of 30-40 samples can be prepared by HPLC analysis in 2-3 hours, with a chromatographic run time of 10 minutes/sample. Calibration curves between 5-250 ng/ml show a good correlation between peak height ratio and MPA concentration, even at low levels. Plasma concentrations of MPA in patients receiving 1 g/day were between 12.6-270 ng/ml in this study, suggesting that the sensitivity of this method, 10 ng/ml, is sufficient for monitoring therapeutic concentrations of MPA. The results show a wide individual variation in plasma concentrations following similar dosing schedules--a finding reported by other workers.     

Detection of trace levels of trichothecene mycotoxins in human urine by gas chromatography-mass spectrometry

A method is described for the simultaneous detection of the trichothecene mycotoxins T-2, HT-2, T-2 tetraol, diacetoxyscirpenol, 15-monoacetoxyscirpendiol, scirpentriol, nivalenol and deoxynivalenol, in human urine. Samples were extracted from Clin Elut columns and cleaned up using reversed-phase Sep-Pak C18 cartridges. Trichothecenes were derivatised as their heptafluorobutyryl esters, and detected by gas chromatography-mass spectrometry-selected-ion monitoring using electron impact ionisation. The method was validated by the analysis of 22 urine samples, spiked and submitted "blind" for analysis by another laboratory. An alternative gas chromatography-mass spectrometry method using negative ion chemical ionisation is also described and a preliminary comparison of the two methods made. The methods enabled levels down to 1 ppb to be detected, with confirmation of identity at levels between 2 and 5 ppb, depending on the toxin.     

Calculation of scattering from stretched copolymers using the tube model: a generalisation of the RPA

There are many experimental situations in which polymer chains are constrained or localised into a small region of space (e.g. melt chains confined to a “tube”, network chains pinned by crosslinks). We show that detailed consideration of the quenched variables is vital in these experiments. This paper provides a crucial link between microscopic models with localising constraints and scattering patterns by a generalisation of the Random Phase Approximation (RPA) which allows for quenched translational variables. A method is developed which deals with correlations between the quenched variables brought about by incompressiblity (for example, in a polymer melt there are correlations between tubes because of the interaction between chains). As an example, the generalised RPA is applied to models based on the Warner-Edwards picture of the tube. Theoretical results for a melt of H-shaped copolymers are compared with experimental scattering. Early results suggest that to fit the scattering we may be forced to relax one of the central assumptions of the tube model; that the tube deforms affinely, that all chains retract by the same amount or that the tube diameter does not couple to the strain. Received 26 October 1998 and Received in final form 19 March 1999     

Hydrolysis and Oxidation Products of the Chemical Warfare Agents 1,2-Bis[(2-chloroethyl)thio]ethane Q and 2,2′-Bis(2-chloroethylthio)diethyl Ether T

Syntheses of diols of structure [HOCH₂CH₂S]₂(CH₂)_n in 86–95% yield from the sodium salt of 2-mercaptoethanol and Br(CH₂)_nBr (n = 1 to 5) or in 60–90% yield from 2-chloroethanol and NaS(CH₂)_nSNa (n = 2 to 5) are described. The diol [HOCH₂CH₂SCH₂CH₂]₂O was prepared in 82% yield from the sodium salt of 2-mercaptoethanol and [ClCH₂CH₂]₂O, and in 88% yield from 2-chloroethanol and [HSCH₂CH₂]₂O. Mono- and bis-sulfoxides and bis-sulfones of these species were prepared in generally high yield by treatment with an equivalent of KIO₄ in aqueous methanol, two equivalents of NaIO₄ in aqueous methanol, or four equivalents of H₂O₂ in trifluoroacetic acid respectively. The compounds are important analytical standards for investigating the fate of the chemical warfare agents sesquimustard Q and oxygen mustard T in environmental samples.     

The Approximation of the Optimal Control of Vibrations—A Geometrical Approach

In this paper we employ concepts from Banach space geometry in order to examine the problem of approximating the optimal distributed control of vibrating media whose motion is governed by a wave equation with a 2n-order self-adjoint and positive-definite linear differential operator. We show that this geometrical approach, arrived at via duality theory, provides the exact framework in which the approximation problem must be placed in order to get the correct convergence results, for it is here that the necessary and sufficient conditions for the approximate norm or time minimal control can be fully developed. Using the theory of Asplund, we are also able to improve the traditional weak^* convergence results for the more difficult case of L^∞ controls. Finally, we consider certain numerical examples which help illustrate our theoretical results.     

Electron beam moiré

A method of writing very high frequency line and dot pattems, in excess of 10,000 lines/mm, is described. This method uses a very small diameter, 10 to 20 nm, beam of electrons to sensitize a 100-nm thick layer of electron resist. The line and dot patterns are produced by etching the sensitized resist. Moiré fringe patterns occur when the line arrays are observed in the scanning electron microscope. Moiré fringes with excellent contrast have been produced at magnifications as high as 1900x. This capability permits e-beam moiré to be employed in micromechanics. Examples of line arrays, dot arrays and moiré fringe patterns on a brass disk and on a tensile specimen fabricated from glass-fiber-reinforced plastic are demonstrated to introduce the possibilities for micromechanics applications.     

A note on chain lengths and the Tutte polynomial

We show that the number of chains of given length in a graph G can be easily found from the Tutte polynomial of G. Hence two Tutte-equivalent graphs will have the same distribution of chain lengths. We give two applications of this latter statement.We also give the dual results for the numbers of multiple edges with given muliplicities.