Transverse Layer Research Articles

High frequency plant regeneration from transverse thin cell layers in Indian mustard (Brassica juncea L.)

An efficient and reproducible plant regeneration system was established using transverse thin cell layers (tTCLs) in five cultivars of Brassjca juncea L. The effects of medium conditions, explant types (tTCLs of hypcotyl and cotyledonary petiole) on shoot regeneration were examined in this study. The maximum shoot regeneration frequency was obtained in Murashige and Skoog (MS) medium supplemented with 4 mg/L 6-benzylaminopurine (BA) and 0.2 mg/L 1-naphthaleneacetic acid (NAA). The hypocotyls derived tTCL explants had more shoot regeneration frequency (52%) than the cotyledonary petiole derived tTCL explants. Shoot induction was further improved by the addition of silver nitrate (<TEX>$AgNO_3$</TEX>) in the regeneration medium. A significant genotypic effect was also observed between the five cultivars; Rai-5 displayed higher capacities to produce shoots than other cultivars. Regenerated shoots were rooted on MS basal medium without PGRs which induced 90% of roots. The plantlets established in greenhouse conditions with 99% survival, flowered normally and set seeds. The regenerated plants were fertile and identical to source plants.

Inhibiting Steel Brace Buckling Using Carbon Fiber-Reinforced Polymers: Large-Scale Tests

A new method is proposed for inhibiting the buckling response of steel braces. The strengthening technique involves attaching a core comprised of mortar blocks to the braces and then wrapping the entire system with carbon fiber-reinforced polymer (CFRP) sheets. An advantage of this method is that the technology can be applied in situ by a single individual with minimal training. Test results of seven specimens subjected to reversed axial loading show that it is feasible to achieve buckling restrained response up to 2% interstory drift. Other than the number of longitudinal fiber layers, it is observed that performance of the strengthening scheme depends upon the size of the core material, the presence of bond between the steel plate and core material, the existence of extra stitch plates for double angle members, and the presence of transverse CFRP layers at the member ends. It is also observed that double angle braces benefit more from the strengthening scheme than single angle braces, which are prone to premature out-of-plane buckling.

An improved micropropagation of Spilanthes acmella L. through transverse thin cell layer culture

An efficient and improved in vitro propagation system for Spilanthes acmella L. using transverse thin cell layer (tTCL) culture system was established. The frequency of shoot regeneration from tTCL nodal segments was affected by concentrations of plant growth regulators and orientation of the explant. MS (Murashige and Skoog in Physiol Plant 15:473–497, 1962) medium with 5.0 mg dm−3 BAP was optimal for shoot regeneration. Upon this medium, the explant inoculated in the upright orientation exhibited a high frequency of shoot regeneration (about 97%), and the highest number of shoots (31.5) per explant. The intact node (1.0–1.5 cm) cultured on the same medium had significantly lower shoot multiplication ability with only 4.5 shoots per responsive explant. As compared to BAP alone, the combination of BAP and Kin or NAA did not have positive effects on shoot multiplication from tTCL nodal segments. Rooting of shoots was achieved on growth regulator free full-strength MS medium. Plantlets were transplanted into soil with 90–100% survival rate.

A probabilistic static fatigue model for transverse cracking in CFRP cross-ply laminates

This paper presents a delayed-fracture model for transverse cracking in CFRP cross-ply laminates under static fatigue loading. First, a delayed-fracture model for a crack in a brittle material was established on the basis of the slow crack growth (SCG) concept in conjunction with a probabilistic fracture model using the three-parameter Weibull distribution. Second, the above probabilistic SCG model was applied to transverse cracking in cross-ply laminates under static fatigue loading. The stress and the length of the unit element in the transverse layers were calculated with the aid of a shear-lag analysis, taking the residual stress into account. The transverse crack density was expressed as a function of applied stress and time with the parameters in the Paris law and the Weibull distribution function specified, in addition to the mechanical and geometrical properties. Unknown parameters were determined from experiment data gathered in static tensile and static fatigue tests. The reproduced transverse crack density at various applied loads agreed well with the experiment results.

Development of a temporary immersion system (RITA®) for mass production of sugarcane (Saccharum spp. interspecific hybrids)

Commercial micropropagation of sugarcane is largely determined by the clonal fidelity and the cost of plants produced. Rapid production of plants in vitro reduces the frequency of offtypes in many species. By exploiting the concept of transverse thin cell layer culture, we have developed a rapid, high frequency direct plant regeneration system, called SmartSett®, for commercial sugarcane cultivars grown in Australia. Similar to conventional micropropagation, labour remains the major cost of this plant production system. Hence, to reduce the labour component, we have integrated the SmartSett® system with the RITA® temporary immersion bioreactor. Thin transverse leaf sections or fragmented leaves cultured on agar-based SmartSett® shoot induction medium were used as the starting material for RITA®. Shoot initiation on semi-solid medium prior to transferring to RITA®, culture immersion frequency, explant size and genotype determined the productivity (number of plants produced per unit culture) of the system. Results obtained with cultivar Q165 indicate that explants cultured for 45 d on SmartSett® shoot induction medium were the most prolific, producing on average 275 shoots per vessel after 45 d of culture in RITA with 1 min immersion every 12 or 24 h. Using the fragmented tissue, 14-d-old explants and 3-mm leaf tissue fragments were the most productive. Experiments with three cultivars (Q117, Q165 and Q205) showed that RITA® culture conditions need to be optimised for each cultivar for maximum plant production.

Progressive cracking mastercurves of the transverse ply in a laminate

AbstractIn this study, progressive cracking of a transverse layer in a cross‐ply composite laminate subjected to tensile loading is considered. Using the results of a probabilistic cracking model, approximate relations for crack density as a function of stress are derived for initiation‐controlled and propagation‐controlled cracking. It is shown that the crack density evolution in the transverse ply can be represented by a mastercurve in suitably normalized coordinates. The mastercurve approach is applied to progressive cracking in glass/epoxy laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Estimation of laminate stiffness reduction due to cracking of a transverse ply by employing crack initiation-and propagation-based master curves

The applicability range of toughness-and strength-based criteria for progressive cracking of a transverse layer in a cross-ply composite laminate subjected to tensile loading is considered. Using a deterministic cracking model, approximate relations for the crack density as a function of stress are derived for initiation-and propagation-controlled types of cracking. The master-curve approach is applied to progressive cracking in glass/epoxy laminates. The accuracy of estimation of laminate stiffness reduction by using crack density master curves is evaluated.

Somatic embryogenesis and plant regeneration from pistil transverse thin cell layers of lemon (Citrus limon)

Callus induction, somatic embryogenesis and plant regeneration were obtained in Citrus limon (L.) Burm. (cv. Femminello) from cultures of pistil transverse thin cell layer explants [(t)TCLs]. Explants were cultured on two different media, based on Murashige and Skoog salts and vitamins, supplemented with 500 mg l−1 malt extract (MSI), or 500 mg l−1 malt extract and 13.3 μM 6-benzylaminopurine (MSII). Sucrose (146 mM) was used as carbon source. Somatic embryos appeared 3 months after culture initiation from stigma and style (t)TCLs; they were observed at the surface of the (t)TCL-derived callus. Although ovary (t)TCLs showed the highest callus formation, they never differentiated somatic embryos. Percentages of embryo formation from (t)TCLs incubated on MSI (13% and 2% for stigma and style, respectively) were lower than those from (t)TCLs incubated on MSII (36% and 7% for stigma and style, respectively). The embryogenic response of stigma (t)TCLs was usually higher than that of style (t)TCLs. After about 3 months, somatic embryos developed into plantlets at high frequencies (57% and 62% for stigma- and style-derived somatic embryos, respectively).

Estudo anatômico do ligamento patelofemoral lateral em joelho de cadáveres

OBJECTIVES: To describe the lateral patellofemoral ligament (LPFL) after anatomical dissection of fresh cadaver knees. The literature shows a particular interest for the LPFL. Such special attention is due to its anatomical and biomechanical importance, and also due to the need to reconstruct the ligament in the cases of medial patellar instability. METHODS: The LPFL was studied in 20 knees of 20 fresh cadavers by means of anatomical dissections. The dissections were standardized and the data were noted down and forwarded to statistical analysis. RESULTS: The LPFL presented a mean 16.05 mm width (standard deviation of 2.48), 42.10 mm length (standard deviation of 8.84). The femoral insertion was found at the lateral femoral epicondyle and with a fan-like expansion of the fibers, predominantly in the posterior region proximal to the lateral epicondyle. In the patella, the insertion found was in the upper-lateral region (in the middle of the upper third of the coronal plan), also with expanded fibers, but less intensely so. In the sagittal plan, the ligament was located in the posterior half of the border of the patella. The LPFL was isolated in the second lateral retinacular layer, the deep transverse retinaculum. CONCLUSION: The LPFL is located in the deep transverse retinacular layer with the presence of a fan-like expansion of its fibers both in the femoral and in the patellar insertions. The insertion is more posterior and proximal at the femoral epicondyle and in the posterior half of the patellar border (sagittal plan) and in the upper-lateral aspect.

SU‐GG‐T‐282: Investigation of Optical Artifacts in a Complex Light‐Scattering Gel Phantom for Optical CT Polymer Gel Dosimetry

Introduction: A test phantom of complex shape was developed to simulate artefacts in dosimetric polymer gels (e.g. PAGAT [1]) when read using cone beam optical CT. Here we report the results of modelling of experimental data using this phantom. Method and Materials: Using a method reported earlier [2], opacity change in an exposed dosimetric gel was simulated by adding known concentrations of Dettol™ to gelatin. Different doses were simulated with gelatin of different opacity (optical density, OD). The phantom was contained is a cylindrical PETE vessel (9.5 cm diameter, 13 cm high). It consisted of an outer mantle of pure gelatin (“zero dose”) surrounding a central, vertical hollow finger. The hollow finger was constructed of 10 transverse layers 15 mm thick of increasing OD, the uppermost layer having the lowest OD. The cavity through the finger centre was filled with a pith of pure “zero dose” gelatin. Inclusion of this central pith simulates a treatment where a high dose region surrounds a low dose region. The phantom was scanned with a Vista Optical CT Scanner (Modus Medical Devices Inc.). Horizontal profiles of OD versus position through each of the 10 layers were obtained from the reconstruction (resolution; 0.25 mm per voxel). Results and Discussion: Consistent with earlier work [1], higher OD slices exhibited dishing artefacts — inner regions within the slice exhibiting an apparent reduction in OD, similar to dishing artefacts in X‐ray CT. More interestingly, the central “zero dose” pith exhibited spurious increases in OD. These effects are modelled by taking into account the back‐reflection of scattered light.

Finite element modelling of transient elastic wave propagation in an inhomogeneous anisotropic fluid/solid multilayer medium: A time-domain method

The axial transmission technique is used clinically for cortical bone assessment. However, ultrasonic propagation in this multiscale medium remains unclear, in particular because of the heterogeneous nature of cortical bone. The aim of this work is to evaluate the effect of spatial gradients of elastic moduli on the ultrasonic response of the bone structure. Therefore, a 2D finite element time-domain method is developed to simulate transient wave propagation in a three-layer medium constituted of an inhomogeneous transverse isotropic solid layer sandwiched between two acoustic fluid layers and excited by an acoustic linear source located in one fluid layer delivering broadband ultrasonic pulses. The model couples the acoustic propagation in both fluid media with the elastodynamic response of the solid. The conditions of continuity are used to model the fluid-structure interaction. A constant spatial gradient of material properties in the direction perpendicular to the layer is considered in the solid structure. In the presence of a gradient, the first arriving signal (FAS) velocity depends on the average material properties when the thickness is smaller than the wavelength (guided wave modes) whereas the FAS velocity depends on the velocity at the surface when the thickness is larger than the wavelength (lateral wave).

Structure and Magnetic Fields in the Precessing Jet System SS 433. I. Multifrequency Imaging from 1998

The Very Large Array has been used at five frequencies to study the structure and linear polarization of SS433 on scales as small as ~0.1 ~ 500 AU. Each jet consists of a sharp, curving ridge-line at the leading edge, plus significant trailing off-jet emission, showing that they are enveloped by diffuse relativistic plasma. No kinematic model with constant jet speed fits our images on all scales, but they are consistent with variations in jet speed of around 10% around the optical value. Our images show continuous jets with bright components occurring simultaneously in the two jets roughly every 35 days. When corrected for projection effects and Doppler boosting, the intensities of the two jets are intrinsically very similar. Fractional linear polarization up to 20% is present along the ridge-lines, while the core is essentially unpolarized. The rotation measures are consistent with a foreground screen with RM ~ +110 radians per meter squared, plus a larger, asymmetrical contribution close to the core. The apparent magnetic fields in the jets are roughly aligned with the ridge-lines in most but not all of each jet. The jet is more highly polarized between the components than in the components themselves, suggesting that the mechanism that creates them compresses a tangled part of the magnetic field into a partially-ordered transverse layer. The off-jet emission is remarkably highly polarized, with m ~ 50% in places, suggesting large-scale order of the magnetic field surrounding the jets. This polarized signal may confuse the determination of magnetic field orientations in the jets themselves. However, the images are consistent with a jet magnetic field that is everywhere parallel to the helices.

Simulation of Microstrip Leaky-Wave Antennas on Inhomogeneous Substrates Using Transverse Resonance and Finite Element Methods

Microstrip leaky-wave antennas offer the potential for wide-bandwidth, thin-profile apertures, albeit with the potential disadvantage of beam steering with respect to operating frequency. These antennas have been extensively studied in the past; however, previously published results have utilized homogeneous substrates. In this article, a substrate with transverse step inhomogeneous layers is investigated with two methods: the transverse resonance method (TRM) and the finite element-boundary integral (FE-BI) method. In this article, the former is generalized for N-layers and used to determine the leaky-wave mode propagating characteristics. Antennas designed using this approach are then simulated using the finite element method to determine the radiation pattern.

Integration of the boussinesq equations for steady channel and jet flows

The equations of long nonlinear waves in round jets and channels of arbitrary cross section are considered with account for the transverse acceleration of the fluid particles (Boussinesq approximation). In the general case of steady flows, the equations in the form of shallow water equations with the pressure expressed in terms of the variational derivative of the kinetic energy of a thin transverse fluid layer, have three first integrals with three arbitrary constants. Examples of solutions of the equations for solitary capillary-gravitation waves in rectangular and triangular channels are presented and compared with the higher approximations. The shape of the free boundary of the round jet is determined. In the case of outflow from a conical nozzle an analytical dependence of the jet contraction ratio on the conicity angle is obtained. The dependence is in agreement with the experimental data for angles of less than 45°.

Depth migration anisotropy analysis in the time domain

ABSTRACTIn areas of complex geology such as the Canadian Foothills, the effects of anisotropy are apparent in seismic data and estimation of anisotropic parameters for use in seismic imaging is not a trivial task. Here we explore the applicability of common‐focus point (CFP)‐based velocity analysis to estimate anisotropic parameters for the variably tilted shale thrust sheet in the Canadian Foothills model. To avoid the inherent velocity‐depth ambiguity, we assume that the elastic properties of thrust‐sheet with respect to transverse isotropy symmetry axis are homogeneous, the reflector below the thrust‐sheet is flat, and that the anisotropy is weak. In our CFP approach to velocity analysis, for a poorly imaged reflection point, a traveltime residual is obtained as the time difference between the focusing operator for an assumed subsurface velocity model and the corresponding CFP response obtained from the reflection data. We assume that this residual is due to unknown values for anisotropy, and we perform an iterative linear inversion to obtain new model parameters that minimize the residuals. Migration of the data using parameters obtained from our inversion results in a correctly positioned and better focused reflector below the thrust sheet. For traveltime computation we use a brute force mapping scheme that takes into account weakly tilted transverse isotropy media. For inversion, the problem is set up as a generalized Newton's equation where traveltime error (differential time shift) is linearly dependent on the parameter updates. The iterative updates of parameters are obtained by a least‐squares solution of Newton's equations. The significance of this work lies in its applicability to areas where transverse isotropy layers are heterogeneous laterally, and where transverse isotropy layers are overlain by complex structures that preclude a moveout curve fitting.

Morphological and physiological characteristics of rapeseed plants regenerated in vitro from thin cell layers in the presence of zinc

Phytoremediation offers owners and managers of metal-contaminated sites an innovative and cost-effective option to address recalcitrant environmental contamination. The use of plants to restore or stabilize contaminated sites, known as phytoremediation, takes advantage of the natural abilities of plants to take up, accumulate or store metals. This includes the use of plants that tolerate and accumulate metals at high levels for phytoextraction and the use of plants growing under conditions that are toxic to other plants, for preventing, for example, soil erosion (phytostabilisation). Rapeseed ( Brassica napus L.) was shown to be able to accumulate substantial amounts of metals combined with high biomass. Brassica napus was therefore selected for heavy metal (HM) tolerance and accumulation through in vitro selection. A selective pressure applied during the neoformation process from transversal thin cell layers (tTCLs) allowed us to select tolerant cells and tissues. Toxic metals (such as Zn) were added to the culture media in order to select zinc-tolerant plants. Exerting a selective pressure during tTCLs regeneration aimed at selecting plants with exceptional zinc tolerance and/or accumulating capacity. The morphological and physicochemical characteristics of regenerated plants cultivated in greenhouse appeared to depend very significantly on the concentration of ZnSO 4 applied during the neoformation process. Plants regenerated in the presence of ZnSO 4 at 100 μM exhibited a greater size and a higher biomass together with flowering precocity. The contents of zinc, chlorophyll, and proline were modified in the regenerated plants. Pre-treatment with an excess of ZnSO 4 (>500 μM) was responsible for a percentage of tTCLs intolerance above 96%. With lower Zn concentrations (100–250 μM), the survival rates (33–15%) were higher. To cite this article: A. Ben Ghnaya et al., C. R. Biologies 330 (2007).

Numerical simulation of the instability of a nonuniform plasma flow: Nonlinear dynamics of slipping instability

A kinetic model is proposed that describes the nonlinear dynamics of the instabilities of a transversely nonuniform plasma flow. It is shown that, in the linear approximation, the model yields the familiar boundary-value problem for the scalar potential in plasma. The slipping instability in a plane waveguide is considered as an example. The general dispersion relation for a flow with a stepwise uniform density profile and with a tangential discontinuity in its longitudinal velocity is analyzed qualitatively. The dynamics of the slipping instability is investigated numerically for a flow that is detached from the waveguide walls and whose longitudinal velocity obeys a linear, a sinusoidal, or a discontinuous distribution. In the nonlinear stage of the instability, the flow expands in such a way as to come into contact with the walls, the spread in the longitudinal velocities remains smaller than the initial velocity variation, and the longitudinal velocities of different transverse layers in the flow are not completely equalized.

High-frequency shoot regeneration through transverse thin cell layer culture in Dendrobium Candidum Wall Ex Lindl.

An efficient in vitro propagation protocol for Dendrobium candidum Wall ex Lindl. using transverse thin cell layer (tTCL) culture system was established. The frequency of shoot regeneration and the number of adventitious buds produced from the regenerated shoots significantly relied on the concentration of plant growth regulators, and the position and orientation of the explant. Murashige and Skoog (MS) medium with half-strength macronutrients and 2% sucrose, supplemented with 1.2 mg l−1 naphthaleneacetic acid (NAA) and 1.2 mg l−1 6-benzyladenine (6-BA), was optimal for shoot regeneration. Upon this medium, the youngest explant inoculated in the upright orientation exhibited a high frequency of shoot regeneration (92%), and the highest number of adventitious buds (an average of 24.5) per explant. Rooting of shoots and adventitious buds was achieved on MS medium with half-strength macronutrients and 2% sucrose with 1.0 mg l−1 NAA and 1.0 mg l−1 indole-3-acetic acid (IAA). Plantlets were transplanted into vermiculite with a 95% survival rate in a greenhouse. Ontogenetic studies revealed that the shoots originated from the stem vascular bundles.

Regional Variations in the Apparent and Tissue-Level Mechanical Parameters of Vertebral Trabecular Bone with Aging Using Micro-Finite Element Analysis

The aim of this study was to obtain the apparent and tissue-level mechanical parameters of vertebral cancellous bones using micro-finite element analysis, and to identify the regional variations and their relative differences with respect to aging. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and then were scanned using a high-resolution micro-Computed Tomography (micro-CT) system. The obtained micro-CT reconstruction models were then converted to micro-finite element models. Micro-finite element analyses were done to determine the apparent Young's moduli and tissue-level Von Mises stress distribution for each trabecular specimen on the longitudinal direction, and medial-lateral and anterior-posterior directions (transverse directions), respectively. Regional variations about the mechanical parameters at both apparent and tissue levels in different transverse layers and vertical columns within and between the two age groups were then analyzed. The results showed significant decreases in the apparent Young's moduli in each direction with aging, and those in the two transverse directions decreased more with aging compared with the longitudinal direction. Furthermore, there were no statistically significant differences between the mechanical parameters in the two transverse directions in both age groups. This study offered an insight into the distributions and variations of mechanical properties within a vertebral body. The mechanical parameters calculated from this study may help in a better understanding of regional fracture risks and the vertebral fracture mechanism in the prevention of osteoporotic fracture in elder individuals.

Effect of genotype, explant size, position, and culture medium on shoot generation of Gerbera jamesonii by receptacle transverse thin cell layer culture

An unique procedure for the mass shoot propagation of Gerbera using receptacle transverse thin cell layer (tTCL) culture procedure was developed. Genotype, flower bud age, explant size, position of receptacle tTCLs and culture media were found to affect the success of culture. Ten interspecific crosses of Gerbera showed different shoot regeneration rates and callus induction via receptacle tTCL culture, all of which had shoot regeneration rates higher than 57%. Flower buds collected on the 10th day resulted in 91% shoot regeneration after 6 weeks of culture on basal MS medium [Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassay with tobacco tissue cultures. Physiol. Plant. 15, 475–497] supplemented with 0.02 mg l −1 thidiazuron (TDZ), 0.8 mg l −1 adenine and 10% (v/v) coconut water (CW). This was significantly higher than those from flower buds on the 7th and 14th days (22% and 54%), respectively. Shoot regeneration rate was the highest (94–100%) in the middle layers of the receptacle. For mass shoot propagation, shoot clusters were subcultured on half-strength MS medium supplemented with 0.5 mg l −1 indole-3-butyric acid (IBA), 0.5 mg l −1 6-benzyladenine (BA) and 2.0 mg l −1 kinetin after every 4 weeks. Plantlets formed when single shoots were cultured on half-strength MS medium containing 1 mg l −1 IBA. All plantlets acclimatized well in the greenhouse.