The cellulose synthesis inhibitor 2,6-dichlorobenzonitrile (DCB) and the DCB analogs 2-chloro-6-fluorobenzonitrile, 3-amino-2,6-dichlorobenzonitrile, and 5-dimethylamino-naphthalene-1-sulfonyL(3-cyano-2, 4-dich1oro)aniline (DCBF) inhibited extracellular adhesive production in the marine diatom Achnanfhes longipes, resulting in a loss of motility and a lack of permanent adhesion. The effect was fully reversible upon removal of the inhibitor, and cell growth was not affected at concentrations of inhibitors adequate to effectively interrupt the adhesion sequence. Video microscopy revealed that the adhesion sequence was mediated by the export and assembly of polymers, and consisted of initial attachment followed by cell motility and eventual production of permanent adhesive structures i n the form of stalks that elevated the diatom above the The herbicide DCB is considered a specific inhibitor of cellulose synthesis in higher plants and algae (Delmer and Amor, 1995). Disruption of plant growth in the presence of DCB has been demonstrated in cotton (Montezinos and Delmer, 1980;, tobacco (Meyer and Herth, 1978), tomato (Shedletzky et al., 1990), barley (Shedletzky et al., 1992), the charophytes Chara and Nitella (Foissner, 1992), and the green alga Vuucheria (Mizuta and Brown, 1992). At micromolar concentrations effective at inhibiting cellulose synthesis, DCB appears to have little or no short-term effect on the synthesis of noncellulosic polysaccharides, nuclear division or DNA synthesis, protein synthesis, respiration, or the in vivo labeling patterns of UDP-Glc, phospholipids, or nucleoside mono-, di-, or triphosphates (Delmer, 1987, and refs. therein).The exact mode of DCB inhibition of cellulose synthesis is not clear. DCB is thought to act primarily on the stages of cellulose synthesis involving polymerization of Glc into a P-4-linked glucan. In an attempt to delineate the mechanism of action of DCB in cotton fibers, used the photoreactive analog DCPA to identify an 18-kD DCB-binding protein thought to function as a regulatory protein for P-glucan synthesis in plants. This acidic protein was found primarily in the 100,OOOg supernatant and has not been further purified or characterized (Delmer and Amor, 1995). Labeling of UDP-Glc in vivo does not appear to be affected by DCB, indicating that its effect is at some later step in the cellulose synthesis process (Delmer and Amor, 1995). The second stage in cellulose microfibril formation involves P-4-linked glucan crystallization into cellulosic microfibrils at the PM. Mizuta and Brown (1992) have summarized the effects of DCB on the PM cellulosesynthesizing complex (the terminal complex) from higher plants and algae. These effects include a decrease or increase in the number of rosette-terminal complexes in Funaria and Triticum, respectively, and an inhibition of microfibril synthesis and assembly of Vauckeria terminal complexes.It has recently been demonstrated that DCB inhibits synthesis of ECM polymers in the noncellulosic red mil
A new melhod for precision surface grinding which is termed "workpiece modulation" is studied in this paper. Simu• lations and experiments have shown that workpiece modulation improves ground surfsce quality. Simulations show that surface tellture as quantified by 20 power spectrum for a single pass with modulation is similar to surfsce texture from a multiple pass grindins operation without modulation. The effect of process parameters of this new process is analyzed by factorially desisned simulations. General rules for selecting grinding process parameters for this new method are siven based on the simulation.
A new method of calibration of coordinate measuring machines (CMMs) and multi-axis machine tools using a 2-D ball array is proposed in this paper. Combined with the use of a 3-D capacitive probe or a magnetic socket, this method can improve the efficiency of calibration greatly. A new kind of artifact called a 2-D ball array is proposed. The 2-D ball array combines the advantages of ball plate and 1-D ball array. Using the 2-D ball array, it is convenient to perform calibration and it is cost effective. Two methods are put forward for using a 2-D ball array in the calibration of the machines. The general method needs the 2-D ball array to be measured at only 4 different positions in the machine working zone, and the 21 parametric errors of the machine can be obtained. The second method is based on the error separation theory. By this method, information of the artifact can be fully utilized without the need to accurately a priori calibrate the artifact. These proposed methods can be used in the calibration and error compensation of CMMs and machine tools.
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