Transverse Layer Research Articles

오리엔탈 백합의 인편 및 줄기의 박판 세포층 절편으로부터 고빈도 자구형성

An efficient system for in vitro bulblet formation of Lilium oriental hybrids(cvs). Casa Blanca and Siberia is described. Transverse thin cell layer(tTCL)(1mm thick) explants of 'Casa Blanca' formed bulblets at a frequency of 97.7％ when cultured on Murashige and Skoog (MS) medium supplemented with 1mg/L 2,4 dichlorophenoxyacetic acid(2,4-D) (On average 15.6 bulblets were formed per explant). The frequency of bulblet formation was drastically reduced when the explant ghickness was thinner than 1 mm. Explants from the outermost layer of bulb scale produced greater frequency of bulblet formation than middle or innermost layer. Among auxins supplemented to culture medium at 1 mg/L, 2,4-D led to greater frequency of bulblet formation on explants than dicamba, picamba, or phenylacetic acid(PAA). tTCL explants from the middle region of the outermost layer bulb scale yielded greater frequency of bulblet formation than the upper or lower region. tTCL stem explants of 'Siberia' formed bulblets at a frequency of 95.3% when cultured on MS medium with 1 mg/L 2,4-D(On average 9.1 bulblets were formed per explant). The system estabilished in this study will be useful for in vitro rapid propagation and genetic transformation of Lilium Oriental hybrids.

Effect of aminoglycoside antibiotics on in-vitro morphogenesis from cultured cells of chrysanthemum and tobacco

Successful genetic transformation of plants requires non-chimeric selection of transformed tissues and their subsequent regeneration. With rare exceptions, most transformation protocols still rely heavily on antibiotics for selecting transgenic cells that contain an antibiotic-degrading selectable marker gene. Here, the morphogenic capacity of in-vitro expiants of chrysanthemum and tobacco stems and leaves (control and transgenic) changed with the addition of aminoglycoside antibiotics (AAs). In a test of 6 AAs, phytotoxicity occurred at concentrations of 10 to 25 and 50 to 100 ng ml.−1 in chrysanthemum and tobacco expiants, respectively. Light conditions as well as expiant source and size also had significant effects. The use of transverse thin cell layers (tTCLs), in conjunction with high initial AA selection levels, supported the greatest regeneration of transgenic material (adventitious shoots or callus) and the lowest number of escapes. Flow-cytometric analyses revealed no endoduplication in chrysanthemum, even at high AA levels. However, this phenomenon was observed in tobacco calli (8C or more), even at low AA concentrations (i.e., 5 to 10 μg mL-1).

Soliton delay line based on a semiconductor superlattice

A new type of delay line intended for soliton pulses is proposed. As a nonlinear medium, a semiconductor superlattice is taken. Solitons that propagate along the superlattice layers are confined in cells bounded by transverse inhomogeneity layers. Solitons are confined and released with the help of an external electric current passing inside the cell.

Electroelastic analysis for a piezoelectric layer with surface electrodes

An electroelastic analysis of a transverse isotropic piezoelectric layer with surface electrodes is made. The piezoelectric layer is infinite long along the poling direction, and the top surface is perfectly bonded to a rigid electrode. The problem is solved via the conformal mapping technique for two cases of elastic boundary conditions on the bottom surface with two spaced electrodes, and the distribution of the electrostatic field in the entire piezoelectric layer is determined in an explicit analytic form, respectively. It is found that for the bottom surface electrodes with vanishing stiffness, the induced strain is singular, but no stress. Instead, for the bottom electrodes with stiffness as infinity, the induced stress is singular, but no strain.

Plant regeneration from thin cell layers in Spinacia oleracea

Caulogenesis and somatic embryogenesis were induced from transverse thin cell layers (tTCLs) of two European (Spinacia oleracea L.) spinach genotypes. Regeneration occurred mostly when tTCLs had been excised from seedlings grown on a preconditioning medium consisting of White's macroelements, Nitsch's microelements, Murashige and Skoog's (MS) vitamins, 6 g l−1 agar and 20 g l−1 glucose. The explants were cultured on MS medium supplemented with sucrose (10, 30, 50 or 80 g l−1) or fructose (5, 10 or 30 g l−1) and several combinations of indole-3-acetic acid (IAA), α-naphtalene acetic acid (NAA), 6-benzylaminopurine (BAP) and gibberellic acid (GA3). Most of the regeneration events were obtained from root explants of the cultivar Carpo. The best result was observed on MS medium supplemented with 50 g l−1 sucrose, 100 μM NAA, 1 μM BAP and 10 μM GA3. After an 8-week culture, the calluses were transferred onto MS medium where shoots and somatic embryos appeared 1 week later. The best root development was obtained on MS medium supplemented with 4.9 μM indole-3-butyric acid (IBA) and 8 g l−1 Phytagel. The plantlets were, then, transferred to soil and developed into well-conformed, fertile plants.

An approximate method of calculating the oscillations of a liquid in inclined elastic cavities and channels

Small oscillations of an ideal incompressible liquid, which partially fills an inclined elastic container (a mobile cavity or channel) of arbitrary form and having a longitudinal plane of symmetry, are considered. The integral condition of continuity of the liquid is obtained by integrating the differential condition of incompressibility and exact satisfaction of the kinematic boundary conditions on the wetted side walls. Using this equation, systems of coordinate functions are constructed which represent the kinematically possible displacements of the liquid, for calculating the oscillations by the Ritz method and the finite-element method. The basic unknown functions, which describe the displacements of the liquid in cross-sections, are approximated by power functions and Legendre functions. Transverse layers of liquid, within the limits of the thickness of which a linear approximation for the unknown functions can be used, are considered as finite elements.

The effect of antibiotics on the in vitro growth response of chrysanthemum and tobacco stem transverse thin cell layers (tTCLs)

Plant tissue culture systems are always under threat of microbial contamination from the air, the tissue culturer, and from the tissue cultured plant itself, and antibiotics can be utilized to eliminate unwanted contaminants from tissue culture. In addition, the genetic transformation of plants requires selection and regeneration of transformed tissues through the use of an antibiotic-degrading gene. This study utilizes a wide range of antibiotic agents to examine their effect on chrysanthemum and tobacco thin cell layer (TCL) tissue culture systems, with an increasing gradient of phytotoxicity being observed: bialaphos ®>chloramphenicol>rifampicin>streptomycin>minomycin>ampicillin>penicillin G=penicillin V, demonstrating that the limiting factor to the use of these agents is in fact the plant. Following the establishment of threshold survival levels, a decrease in explant survival and reduced biomass, malformation of roots and inhibition of shoot formation in chrysanthemum was observed, and further, in the case of tobacco endoreduplication.

Aminoglycoside antibiotics affect the in vitro morphogenic response of chrysanthemum and tobacco

Broadly the success of genetic transformation of plants requires non-chimeric selection of transformed tissues and its subsequent regeneration. With rare exceptions, most plant transformation protocols still heavily utilize antibiotics for the selection of transgenic cells containing an antibiotic-degrading selectable marker gene. The morphogenic capacity of in vitro chrysanthemum and tobacco stem and leaf explants change with the addition of aminoglycoside antibiotics (AAs). Of 6 antibiotics tested, phytotoxicity occurred at 10-25 and 50-100 pgml-I in chrysanthemum and tobacco explants, respectively, depending on the size of the explant and the timing of application. The presence of light or darkness also had a significant effect. The use of transverse thin cell layers (tTCLs) in conjunction with high initial AA selection levels supported the greatest regeneration of transgenic material (adventitious shoots or callus) and the lowest number of escapes. Flow cytometric analyses demonstrate that regeneration can be predicted in both species, depending on the ploidy level of the callus. Endoreduplication was not observed in chrysanthemum, even at high AA levels, but occurred (8C or more) in tobacco callus, even at low AA concentrations (5-10 pgml-1). The higher the AA level, the greater the DNA degradation and the lower the 2C and 4C values.

Effect of Matrix Cracks on Damping in Unidirectional and Cross-Ply Ceramic Matrix Composites

The paper elucidates the methodsof estimating damping in ceramic matrix composites (CMC) with matrix cracks. Unidirectional composites with bridging matrix cracks and cross-ply laminates with tunneling cracks in transverse layers and bridging cracks in longitudinal layers are considered. It is shown that bridging matrix cracksdra matically increase damping in unidirectional CMC due to a dissipation of energy along damaged sections of the fiber–matrix interface (interfacial friction). Such friction is absent in the case of tunneling cracks in transverse layers of cross-ply laminates where the changes in damping due to a degradation of the stiffness remain small. However, damping in cross-ply laminates abruptly increases, if bridging cracks appear in the longitudinal layers.

Effect of matrix cracking in cross-ply ceramic matrix composite beams on their mechanical properties and natural frequencies

The present paper illustrates the effect of matrix cracks in longitudinal and transverse layers of cross-ply ceramic matrix composite (CMC) beams on their mechanical properties and vibration frequencies. Even in a geometrically linear problem considered in the paper, the physical non-linearity is introduced by matrix cracks and interfacial fiber-matrix friction in longitudinal layers. A closed-form solution for mechanical properties of a cross-ply CMC beam with matrix cracks is developed in the paper. The frequency of free vibrations of a simply supported beam is derived as a function of the amplitude, accounting for the effect of matrix cracks. As shown in the paper, the prediction of the natural frequencies of cross-ply CMC beams with matrix cracks in both longitudinal and transverse layers is possible using simple, yet accurate, approximate equations.

δD-δ18O relationships on a polythermal valley glacier: Midtre Lovénbreen, Svalbard

This paper outlines the results of stable isotope (δD-δ18O) analysis of snow and glacier ice undertaken as part of a larger study concerning structural glaciology, debris entrainment and debris transport patterns at Midtre Lovénbreen, Svalbard. Samples of fresh snow were collected from the glacier surface in spring 1999 and samples of surface glacier ice and basal ice samples were collected in summer 1999. When plotted on bivariate co-isotopic diagrams (δD-δ18O), the slopes obtained for snow and unmodified glacier ice (6.4 and 6.9, respectively) are less steep than those for the basal ice layer and transverse ice layers on the ice surface (7.6 and 7.7, respectively). The difference in the slope of these lines is not statistically significant at the sample size (50) used in this study. The results indicate that although stable isotope analysis clearly has potential for studies of debris entrainment, transport and structural glaciology, difficulties remain with applying this technique. It is therefore not possible to apply these isotopic techniques to ice facies of unknown origins. In particular, large sample numbers are required to establish statistical differences and high-resolution sampling of specific ice facies may be necessary to establish isotopic differences.

Modeling creep and recovery behavior of a quasi-isotropic laminate with transverse cracking

An analytical model is proposed for predicting creep and recovery behavior of a quasi-isotropic laminate having transverse cracks in transverse layers. The analysis is established on the basis of a shear lag analysis in conjunction with a viscoelasticity theory. The strain is obtained in the Laplace transformed space and its original function is calculated by means of a numerical inverse Laplace transform technique. Creep and recovery tests are conducted for a quasi-isotropic glass/epoxy (GFRP) laminate with and without transverse cracking at a room temperature. The predicted strain response is in reasonably good agreement with experimental results.

Effect of 2,4-D and 4-CPPU on somatic embryogenesis from stigma and style transverse thin cell layers of Citrus

Callus induction, somatic embryogenesis and plant regeneration were obtained in lemon [Citrus limon (L.) Burm. cv `Femminello'] and sweet orange [C. sinensis (L.) Osb. cv `Washington Navel GS'] from cultures of stigma and style transverse thin cell layer explants [(t)TCLs]. Explants were cultured on 16 different media, based on the nutrients and vitamins of Murashige and Tucker medium (MT) supplemented with different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and N-(2-chloro-4-pyridyl)-N′-phenylurea (4-CPPU). Sucrose (146 mM) was used as the sole carbon source. Somatic embryos arose from callus at the surface of stigma and style (t)TCLs 3–5 months after culture initiation of both sweet orange and lemon. The percentages of embryo formation from style (t)TCLs ranged from 0% (the media containing 2,4-D) to 16.0% (the medium supplemented with 4 μM 4-CPPU) for C. limon. Better results were obtained when stigma (t)TCLs from C. limon were used; in fact, percentages ranged from 0% on the media containing 2,4-D, with the only exception for the medium supplemented with 0.4 μM 2,4-D, to 24.8% on medium with 4 μM 4-CPPU. The embryogenic response of lemon (t)TCLs was usually higher than for sweet orange (t)TCLs. After about 3 months, somatic embryos developed into plantlets at high frequencies ranging from 53% to 75% for sweet orange and lemon style derived embryos, respectively.

The changes in shoot regeneration potential of protocorm-like bodies derived from Lilium longiflorum young stem explants exposed to medium volume, pH, light intensity and sucrose concentration pretreatment

SummaryAn efficient system has been developed for the in vitro shoot regeneration of Lilium longiflorum Thunb. by culturing pretreated protocorm-like bodies (PLBs) derived from young stem transverse thin-cell layers (tTCLs) exposed to various treatments of different medium volumes, pH, light intensity and sucrose concentrations. After 30.d culture in 50 ml plastic petri dishes containing Murashige and Skoog medium supplemented with 0.2 mg l–1 thidiazuron (TDZ), the explants formed PLBs in all treatments. PLBs with the highest fresh weight were obtained after 30.d of culture when explants were cultured on MS medium containing 0.2 g l–1 TDZ with either 25 ml volume, pH 6.1, 20 μmol m–2 s–1 light intensity, or with 30 g l–1 sucrose supplement. However, most shoot formation from PLBs was found using MS hormone-free medium with either 30 ml volume, pH 5.0, 40 μmol m–2 s–1 light intensity, or with 20.g l–1 sucrose after 30.d of culture. The highest shoot regeneration of L. longiflorum was derived from PLBs when explants were exposed to various media, indicating that the choice of explants and pretreatment in the medium with optimum volume, pH, light intensity and sucrose concentreation are needed.

Vibrations of sandwich panels and beams with matrix cracks in the facings

The paper presents the solution of the vibration problem for sandwich panels and beams with matrix cracks in transverse layers of cross-ply facings. The closed-form solution is obtained by assumption that the panels can be characterized by the first-order shear deformation theory. The analysis accounts for a difference in the response of the facings with open and closed matrix cracks. Extension of the solution to the case of multi-skin panels is also discussed in the paper. In addition, the problem of vibration of sandwich beams with matrix cracks in the transverse layers and delaminations generating from the tips of transverse cracks is considered. As shown in this paper, although the presence of delaminations results in a larger reduction of the stiffness and free vibration frequencies than transverse cracking by itself, the changes in the frequencies remain relatively small.

Two-dimensional analysis of magnetoimpedance in magnetic/metallic multilayers

This article concerns the effect of the in-plane film size on the magnetoimpedance (MI) characteristics in magnetic/metallic multilayers. The problem is approached by a two-dimensional solution of the Maxwell equations in a symmetrical three-layer film. If the edge effect is neglected, the magnetic flux generated by the current flowing through the film is confined within the outer magnetic layers. In a finite width sandwich, the flux leaks through the inner conductor. This process eventually results in a considerable drop in MI ratio if this width is smaller than the critical flux decay length depending on the effective transverse permeability, layer thickness, and frequency.

Effects of activated charcoal, explant size, explant position and sucrose concentration on plant and shoot regeneration of Lilium longiflorum via young stem culture

An efficient system for the in vitro plant and shootregeneration of Lilium longiflorum was developed andaccomplished using transverse thin cell layers (tTCL) of young stems.tTCLs were cut transversely along young stems from which the shoot-tipshad been removed. Sections were measured accurately using a graded gridand were cut in 4 mm × 4 mm × 1 mm cubes, eliminatingepidermal tissue, and were cultured on one-half MS medium containing 8 gl−1 agar, different sucrose concentrations (10, 20, 30 or 40g l−1), and with or without 1 mg l−1 activatedcharcoal (AC). Plants formed on the surface of tTCLs within 60 days onone-half MS medium containing 8 g l−1 agar and 20 gl−1 sucrose. Sections of 1 mm taken just below the apicalarea developed buds within 15 days, whereas the sections closer to thebase required about 45 days. Shoot regeneration was enhanced whensucrose concentration was used at 30 or 40 g l−1 after 60days of culture. No root formation occurred. Both shooting and rootingoccurred when sucrose was used at 20 g l−1. The plantletswere transferred to soil and grew well under greenhouseconditions.

Matrix cracking in transverse layers of cross-ply beams subjected to bending and its effect on vibration frequencies

Abstract The solution for the matrix crack distribution in transverse layers of a cross-ply beam subjected to bending is developed based on the model of Han and Hahn (Compos Sci Technol 35 (1989) 377). This solution accounts for a bimodulus-type of the material response. As a result, it is possible to predict the extent and distribution of matrix cracks as well as the stiffness distribution in the beam subjected to bending, accounting for residual thermal stresses. The results of the solution of the bending problem are employed in the analysis of free and forced vibrations of a cross-ply beam with matrix cracks in transverse layers. The solution differs from the case of vibrations of an intact beam due to a difference in response of damaged layers under tension and compression. The results are shown for the natural frequency of a representative ceramic matrix composite (CMC) beam.

Numerical simulation of turbulent flow in a pipe oscillating around its axis

The turbulent flow in a cylindrical pipe oscillating around its longitudinal axis is studied via direct numerical solution of the Navier–Stokes equations, and compared to the reference turbulent flow in a fixed pipe and in a pipe with steady rotation. The maximum amount of drag reduction achievable with appropriate oscillations of the pipe wall is found to be of the order of 40%, hence comparable to that of similar flows in planar geometry. The transverse shear layer due to the oscillations induces substantial modifications to the turbulence statistics in the near-wall region, indicating a strong effect on the vortical structures. These modifications are illustrated, together with the implications for the drag-reducing mechanism. A conceptual model of the interaction between the moving wall and a streamwise vortex is discussed.

Somatic embryogenesis and direct shoot regeneration of rice ( Oryza sativa L.) using thin cell layer culture of apical meristematic tissue

Summary A new and simple method was designed to directly produce shoot regeneration of rice ( Oryza sativa L.), within a short time-span, with a high yield, and without the need for subculture. Transverse thin cell layers (tTCLs) excised from the shoot apical meristems of two-week old seedlings, which received pretreatment in darkness with 2,4-D from 1–20 μmol/L, were placed on Murashige and Skoog. (1962) medium supplemented with 3% (w/v) sucrose and a combination of 2,4-D varying from 1–20 μmol/L and BAP varying from 1–10 μmol/L. Somatic embryos and the embryo-like structures which developed into shoots were kept in the dark for 2 weeks after the culture of tTCL explants, and produced a maximum of 6 somatic embryos and 16 shoots per tTCL explant. Also important for shoot regeneration was the effect of the 2-week period of exposure to darkness followed by light exposure. The regenerated shoots were transferred to a medium with no hormone for rooting. More than 95% of plantlets developed successfully when they were transferred to the greenhouse.