Oblique Walls Research Articles

Callose in leptoid cell walls of the moss Polytrichum and the evolution of callose synthase across bryophytes.

Leptoids, the food-conducting cells of polytrichaceous mosses, share key structural features with sieve elements in tracheophytes, including an elongated shape with oblique end walls containing modified plasmodesmata or pores. In tracheophytes, callose is instrumental in developing the pores in sieve elements that enable efficient photoassimilate transport. Aside from a few studies using aniline blue fluorescence that yielded confusing results, little is known about callose in moss leptoids. Callose location and abundance during the development of leptoid cell walls was investigated in the moss Polytrichum commune using aniline blue fluorescence and quantitative immunogold labeling (label density) in the transmission electron microscope. To evaluate changes during abiotic stress, callose abundance in leptoids of hydrated plants was compared to plants dried for 14 days under field conditions. A bioinformatic study to assess the evolution of callose within and across bryophytes was conducted using callose synthase (CalS) genes from 46 bryophytes (24 mosses, 15 liverworts, and 7 hornworts) and one representative each of five tracheophyte groups. Callose abundance increases around plasmodesmata from meristematic cells to end walls in mature leptoids. Controlled drying resulted in a significant increase in label density around plasmodesmata and pores over counts in hydrated plants. Phylogenetic analysis of the CalS protein family recovered main clades (A, B, and C). Different from tracheophytes, where the greatest diversity of homologs is found in clade A, the majority of gene duplication in bryophytes is in clade B. This work identifies callose as a crucial cell wall polymer around plasmodesmata from their inception to functioning in leptoids, and during water stress similar to sieve elements of tracheophytes. Among bryophytes, mosses exhibit the greatest number of multiple duplication events, while only two duplications are revealed in hornwort and none in liverworts. The absence in bryophytes of the CalS 7 gene that is essential for sieve pore development in angiosperms, reveals that a different gene is responsible for synthesizing the callose associated with leptoids in mosses.

The Lattice Boltzmann Method Using Parallel Computation: A Great Potential Solution for Various Complicated Acoustic Problems

This paper proposes the D2Q5 Lattice Boltzmann method (LBM) method, in two dimensions with five discrete lattice velocities, for simulating linear sound wave propagation in closed rooms. A second-order linear acoustic equation obtained from the LBM method was used as the model equation. Boundary conditions at the domain boundary use the bounce-back scheme. The LBM numerical calculation algorithm in this paper is relatively simpler and easy to implement. Parallelization with the GPU CUDA was implemented to speed up the execution time. The calculation results show that the use of parallel GPU CUDA programming can accelerate the proposed simulation 27.47 times faster than serial CPU programming. The simulation results are validated with analytical solutions for acoustic pulse reflected by the flat and oblique walls, the comparisons show very good concordance, and the D2Q5 LBM has second-order accuracy. In addition, the simulation results in the form of wavefront propagation images in complicated shaped rooms are also compared with experimental photographs, and the comparison also shows excellent concordance. The numerical results of the D2Q5 LBM are promising and also demonstrate the great capability of the D2Q5 LBM for investigating room acoustics in various complexities.

Diversity of tracheary elements of Aspleniaceae

Abstract Tracheary elements can be classified as tracheids or vessel elements. In ferns, both cell types and even cells with intermediate characteristics can be observed. For a long time, the methods employed in the study of these cells were questioned and consequently their classification as well. In the present work, we analyze the stem tracheal elements of 13 Aspleniaceae species, occurring in different habitats and belonging to different clades. The samples were cut, dried on a hotplate, metallized, and analyzed in SEM. In general, the Asplenium species analyzed contain elongated conducting cells with oblique end walls, with scalariform thickening on all faces of the cell. The presence of pit membranes, however, varies greatly among species, it being possible to observe species with tracheids, with intermittent perforation plates, and with vessel elements.

On the mean overtopping rate of rubble mound structures

Estimation of the mean overtopping discharge is a major task in the design and assessment of the crest level of rubble mound structures such as breakwaters and seawalls. The tolerable mean overtopping rates are given based on the associated risk and wave characteristics. Several empirical formulas have been developed for the prediction of mean overtopping discharge at coastal structures. These formulas can be applied to a wide variety of coastal structures, but have limited accuracy and/or do not reflect the physics of the phenomena. The main aim of this study is to overcome these issues for rubble mound structures by considering the physics of the process in the formula development. To achieve this, first, the references used in the extended CLASH database (also called the EurOtop-2018 database), were scrutinized, the reported wave characteristics were corrected (if required) and the rubble mound structure subset was extended using a recent study. Then noting that overtopping occurs when the wave runup exceeds the freeboard, the difference between the maximum wave runup and crest freeboard was considered as the governing parameter in the mean overtopping discharge formula. In the developed formula, a semi-empirical relationship between the mean overtopping and wave runup has been established. The performances of the developed formulas and existing ones were evaluated both qualitatively and quantitively. Accuracy metrics such as RMSE and BIAS indicated the superiority of the developed simple formula. Finally, a design formula to consider uncertainty and some guidelines are provided for practitioners. • A robust formula was derived for the mean overtopping of rubble mound structures. • The formula has a compact form and includes effects of governing parameters such as the wave runup and crest width. • The formula was evaluated for a wide range of cases such as oblique waves and wave walls as well as prototype data. • A probabilistic formula was also given to include the uncertainty and safety in the design.

Thermal investigation and physiochemical interaction of H2O and C2H6O2 saturated by Al2O3 and γAl2O3 nanomaterials.

The interaction of nanoparticles and base solvents of different nature attained much interest of the researchers in the recent time. These use in medication, detection of cancer cells, applied thermal engineering, and electrical and mechanical engineering. Among the broad range of applications, investigation of nanofluid through converging/diverging channel is important which is of much interest in the field of medical sciences. The core purpose of this study is to introduce a new heat transfer model for two natures of nanofluids with bi host solvents. The model in hand achieved through nanofluid expressions, similarity equations and induction of novel dissipation effects. At later stage, numerical treatment is performed to explore the actual behaviour of nanofluids inside the oblique walls which is very important. From the drawn results, it is found that the motion could be controlled by expanding the channel walls () and high Re and in Al2O3-H2O it is optimum. The nanofluids based on Al2O3 and C2H6O2 have much ability to transmit heat than the other nanofluids. Moreover, dissipation effects () played significant role and boosted the temperature while keeping and , respectively. Also, the study is validated and achieved good agreement between existing and the current study.

Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

Closed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

CFD Study of Airflow and Microclimate Patterns Inside a Multispan Greenhouse

Understanding and improving greenhouses requires the analysis and modelling of energy and mass exchange phenomena. The mastery of all these physical mechanisms can make it possible to propose technological solutions to control the greenhouse climate. This study presents an analysis and simulation of air flow, temperature and humidity patterns ,in ½-ha multi-span greenhouse with oblique side walls,covered by insect proof nets.The site is located in the coastal area of southern Morocco. The fundamental calculation of climatic conditions is based on CFD, wich uses the mass, momentum and energy conservation equations. The dynamic influence of the insect screens and tomato crop on airflow movement, was described ,using the concept of the porous medium approach proposed by Darcy and Forchheimer.The coupling of convective and radiative exchanges at the plastic roof cover is considered. A good agreement was observed between the measured and simulated values for inside air temperatures and relative humidity. Insect screens significantly reduced airflow and increased thermal gradients inside the greenhouse. The results clearly showed the heterogeneity of the greenhouse’s internal climate, which infects agricultural production in quantity and quality

Pliocene Albizia (Fabaceae) from Jharkhand, eastern India: reappraisal of its biogeography during the Cenozoic in Southeast Asia

Albizia, a diverse tree genus, occupies monsoonal warm humid rain forests in tropical and subtropical regions. We recovered a well-preserved compound fossil leaf and two fossil fruits of Albizia (Fabaceae) from the latest Neogene (Rajdanda Formation: Pliocene) sediments of Jharkhand of the Chotanagpur Plateau, eastern India. On the basis of the architectural features of the fossil leaf, a new species is established as A. mahuadanrensis Hazra, Hazra and Khan, n. sp., characterised by a bipinnate, compound leaf having a rachis bearing opposite, asymmetrically ovate to sub-rhomboid leaflets, pulvinus on leaflet petiolule and brochiodromous secondary veins. Based on both morphological and anatomical characters of the fossil fruits, A. palaeoprocera Hazra, Hazra and Khan, n. sp. is erected, characterised by flattened to broadly linear shaped, wingless fruits; ovate-elliptic shaped seed chambers having ellipsoidal seeds in one series; irregularly polygonal to rectangular epidermal cells with oblique end walls and randomly oriented, scattered, paracytic stomata. Analysis of Albizia fossil occurrences indicates that the legume taxon was common in Neogene forests of India and elsewhere. The present-day distribution of the closely affiliated modern species of the fossil taxa indicates a warm and humid tropical environment during the time of deposition. We also review the biogeographic history of Albizia in India and other Asian countries.

The morphological characteristics and classification of vascular parenchyma cells in bamboo, Phyllostachys edulis (Carr.) J. Houz

Abstract Vascular parenchyma cells (VPCs) provide a critical metabolic and energetic link for xylem transport of water and mineral nutrients and phloem transport of photoassimilates. Understanding the morphology of these cells is required to understand their function. This study describes the morphology and classification of VPCs of moso bamboo by light microscopy (LM) and scanning electron microscopy (SEM). The key results revealed that vascular parenchyma could be divided into three categories according to cell geometric morphology: cells with two transverse end walls, cells with one oblique end and one transverse end walls, and cells with two oblique end walls. Additionally, there were two types of thickening patterns of the secondary wall, uniform and reticulate thickening, and both diffuse pitting and opposite-alternate pitting were observed. The average length, width, lumen diameter, double wall thickness, and area of the VPCs were 139.0 μm, 17.3 μm, 10.4 μm, 6.9 μm, and 51.1 μm2, respectively. Most VPCs were slender and thin-walled, and growth of the VPCs was not correlated in either the length or the width directions.

Stem and leaf structure of Searsia erosa (Thunb.) Moffett (Anacardiaceae) with systematic, ecological and ethnobotanical implications

The anatomy of stems and leaves of the southern African evergreen shrub Searsia erosa (Anacardiaceae) was studied. This species shows the suite of typical traits of Anacardiaceae, such as the presence of secretory canals in the cortex, secondary phloem, wood rays and vascular bundle of leaf midrib, pericyclic fibres in nearly continuous bands, compound sieve plates on oblique walls, simple perforation plates, alternate intervessel pitting, and septate libriform fibres. Like other Searsia species, S. erosa has abundant sclereids in non-conducting secondary phloem, multicellular peltate glandular trichomes on leaf epidermis, short vessel elements and minute intervessel pits; two latter characters are thought to be diagnostic for this genus. Unlike Asian species of Searsia, S. erosa lacks marginal axial parenchyma as well as prismatic crystals in axial parenchyma and in libriform fibres, but it shows the helical thickenings on vessel walls. The presence of the last trait in a southern African species agrees with association of helical thickenings with the regions that experience water stress. The tangential expansion of secondary phloem in S. erosa and probably in other Searsia species is mainly performed by considerable increase in volume of its cells by their sclerification. Such a way of bark growth in girth is out of scope of bark anatomists. Searsia erosa is distinctive from other congeneric species in its hypostomatous leaves with abundant glandular trichomes on adaxial side. This condition demonstrates a labor division between the adaxial side with glandular trichomes that may contribute to leaf protection, and the stomata-bearing abaxial side providing the gas exchange. Unlike most members of Anacardiaceae, the secretory canals of S. erosa produce the oleoresin containing terpenoids (essential oils) and lipids, but lack polysaccharides. The abundance of glandular trichomes and secretory canals producing terpenoids is a presumable reason of the use of S. erosa in traditional medicine by the Basotho people.

Development of hybrid method for coupled conduction-radiation heat transfer in two-dimensional irregular enclosure considering thermo-radiative effects and varying thermal conductivity

PurposeThis study aims to perform a comprehensive investigation to model the thermal characteristics of a coupled conduction-radiation heat transfer in a two-dimensional irregular enclosure including a triangular-shaped heat source.Design/methodology/approachFor this purpose, a promising hybrid technique based on the concepts of blocked-off method, FVM and DOM is developed. The enclosure consists of several horizontal, vertical and oblique walls, and thermal conductivity within the enclosure varies directly with temperature and indirectly with position. To simplify the complex geometry, a promising mathematical model is introduced using blocked-off method. Emitting, absorbing and non-isotropic scattering gray are assumed as the main radiative characteristics of the steady medium.FindingsDOM and FVM are, respectively, applied for solving radiative transfer equation (RTE) and the energy equation, which includes conduction, radiation and heat source terms. The temperature and heat flux distributions are calculated inside the enclosure. For validation, results are compared with previous data reported in the literature under the same conditions. Results and comparisons show that this approach is highly efficient and reliable for complex geometries with coupled conduction-radiation heat transfer. Finally, the effects of thermo-radiative parameters including surface emissivity, extinction coefficient, scattering albedo, asymmetry factor and conduction-radiation parameter on temperature and heat flux distributions are studied.Originality/valueIn this paper, a hybrid numerical method is used to analyze coupled conduction-radiation heat transfer in an irregular geometry. Varying thermal conductivity is included in this analysis. By applying the method, results obtained for temperature and heat flux distributions are presented and also validated by the data provided by several previous papers.

Fabrication of Antireflective Nanostructures on a Transmission Grating Surface Using a One-Step Self-Masking Method.

Suppression of Fresnel reflection from diffraction grating surfaces is very important for many optical configurations. In this work, we propose a simple method to fabricate subwavelength structures on fused-silica transmission grating for optical antireflection. The fabrication is a one-step self-masking reaction ion etching (RIE) process without using any masks. According to effective medium theory, random cone-shaped nanopillars which are integrated on the grating surface can act as an antireflective layer. Effects of the nanostructures on the reflection and transmission properties of the grating were investigated through experiments and simulations. The nanostructure surface exhibited excellent antireflection performance, where the reflection of the grating surface was suppressed to zero over a wide range of incident angles. Results also revealed that the etching process can change the duty cycle of the grating, and thus the diffraction orders if there are oblique lateral walls. The simulation results were in good agreement with the experimental ones, which verified our physical comprehension and the corresponding numerical model. The proposed method would offer a low-cost and convenient way to improve the antireflective performance of transmission-diffractive elements.

Myosin XI-K is involved in root organogenesis, polar auxin transport, and cell division.

The interplay between myosin- and auxin-mediated processes was investigated by following root development in the triple myosin knockout mutant xi-k xi-1 xi-2 (3KO). It was found that the 3KO plants generated significantly more lateral and adventitious roots than the wild-type plants or the rescued plant line expressing functional myosin XI-K:yellow fluorescent protein (YFP; 3KOR). Using the auxin-dependent reporter DR5:venus, a significant change in the auxin gradient toward the root tip was found in 3KO plants, which correlated with the loss of polar localization of the auxin transporter PIN1 in the stele and with the increased number of stele cells with oblique cell walls. Interestingly, myosin XI-K:YFP was localized to the cell division apparatus in the root and shoot meristems. In anaphase and early telophase, XI-K:YFP was concentrated in the midzone and the forming cell plate. In late telophase, XI-K:YFP formed a ring that overlapped with the growing phragmoplast. Myosin receptors MyoB1 and MyoB2 that are highly expressed throughout the plant were undetectable in dividing cells, suggesting that the myosin function in cell division relies on distinct adaptor proteins. These results suggest that myosin XIs are involved in orchestrating root organogenesis via effects on polar distribution of auxin responses and on cell division.

Method for Parametric Shaping Architectural Free Forms Roofed with Transformed Shell Sheeting

An innovative method for shaping attractive architectural free forms of buildings is proposed. Consistency of shell roofs and plane-walled oblique elevations of the building free forms is preserved due to utilization of specific geometrical tetrahedrons controlling general forms of entire buildings. The method proposed enables shaping roofs as warped shell forms made up of plane steel sheets folded in one direction and connected to each other along their longitudinal edges to obtain a plane strip. Next, the strip is elastically transformed into a shell shape so that a freedom of the width increments of each shell fold would be ensured. Such effective sheet shape transformations make it possible to limit the negative influence of these initial fold’s shape changes on the strength and stability of the designed roof shell. The method also allows to shape oblique plane elevation walls almost freely both individual buildings and their complex structures.

A method of determining effective elastic properties of honeycomb cores based on equal strain energy

A computational homogenization technique (CHT) based on the finite element method (FEM) is discussed to predict the effective elastic properties of honeycomb structures. The need of periodic boundary conditions (BCs) is revealed through the analysis for in-plane and out-of-plane shear moduli of models with different cell numbers. After applying periodic BCs on the representative volume element (RVE), comparison between the volume-average stress method and the boundary stress method is performed, and a new method based on the equality of strain energy to obtain all non-zero components of the stiffness tensor is proposed. Results of finite element (FE) analysis show that the volume-average stress and the boundary stress keep a consistency over different cell geometries and forms. The strain energy method obtains values that differ from those of the volume-average method for non-diagonal terms in the stiffness matrix. Analysis has been done on numerical results for thin-wall honeycombs and different geometries of angles between oblique and vertical walls. The inaccuracy of the volume-average method in terms of the strain energy is shown by numerical benchmarks.

PARAMETRIC SHAPING OF CONSISTENT ARCHITECTURAL FORMS FOR BUILDINGS ROOFED WITH CORRUGATED SHELL SHEETING

Abstract The paper presents a method for a parametric shaping of innovative building free forms covered with corrugated steel shell roofs and flat glass elevation walls. Each shell roof is made of plane steel sheets folded in one direction and transformed elastically into spatial shape. The obtained shapes can be really diversified sectors of various ruled surfaces. Therefore there is a great need for creating such a method that leads to a fine integration of the shapes of a free form shell roof and plane oblique elevation walls for each building free form. Thus, it was elaborated the innovative parametric method, whose algorithm allows for seeking attractive and consistent architectural free forms by means of computer programs. A relatively small set of initial relevant parameters enables the designer intuitively to affect the attractiveness of the designed free forms. Some special attention is paid to selected fine proportions of these geometrical parameters leading to the really attractive architectural free forms.

Improving the Yamaguchi4 Decomposition Method Using Selective Polarization Orientation Compensation

. The Polarization Orientation Compensation (POC) method has been proposed to resolve overestimation of the volume component induced by topographical slopes and oblique building walls during model-based decompositions. The approach, however, can result in an underestimation of volume scattering within forests. This article proposes a novel method to improve the Yamaguchi 4-component (hereafter referred to as the Yamaguchi4) decomposition approach using POC. The scattering power of the decomposition components before and after POC is used to determine whether a pixel needs orientation compensation. The proposed method provides a number of advantages. First, the cross-polarized component, created by topographical slopes and man-made structures whose main scattering center is at an oblique direction with respect to radar illumination, is minimized. Oblique building blocks do not present the same volume as forests but, instead, result in double-bounce scattering. Second, this method resolves issues related to decreasing representations of vegetation according to the 4 scattering components when the volume-scattering power from forests is reduced. The new method was applied to currently available data, and positive results were achieved.

A new species of the genus Sequoiadendron Buchholz (Cupressaceae) from the Upper Cretaceous of the Enmyvaam River Basin, Central Chukotka

A new conifer species, Sequoiadendron tchucoticum A. Sokolova from the Emuneret Formation on the Enmyvaam River (Anadyr River Basin) is described. It is established based on a thorough study of the morphology and epidermal features of shoot impressions, using scanning electron microscopy. The new species has polymorphic shoots with helical branching and three main leaf types: scalelike, subulate, and falcate. Leaves are amphistomatic; amphicyclic stomata are mostly obliquely arranged; ordinary epidermal cells are rectangular, frequently with oblique end walls, and their length-to-width ratio reaches 15: 1. Shoots of the new species prevail among conifers of the Ust’-Emuneret Assemblage. The age of the deposits enclosing the assemblage is debated; according to the latest data, it is estimated as Santonian–Early Campanian.

Barrancaceae: A new green algal lineage with structural and behavioral adaptations to a fluctuating environment.

To enhance our knowledge of the diversity of microalgae, a phycological survey of the Canary Islands (Spain) was undertaken. Here we report the discovery of a (semi)terrestrial green filamentous alga isolated from a steep volcanic canyon on La Palma. This alga is continually exposed to changing weather conditions (floods vs. droughts) and thus provides a good opportunity to investigate possible adaptations to a semiterrestrial habitat with large fluctuations of environmental parameters. We used axenic cultures, simulated flood and drought stresses and studied their effect on the life history of the alga using light, confocal laser scanning and scanning electron microscopy including fluorescent staining. Furthermore, phylogenetic analyses using rDNA sequence comparisons were performed. Three specific life-history traits that likely represent adaptations to the fluctuating environment of the canyon were observed: (1) fragmentation through "filament splitting", a unique branching mechanism not reported before in algae and initiated by formation of oblique cross walls, (2) aplanospore formation, and (3) reproduction by multiflagellate zoospores with 4-24 flagella arranged in groups of four. Phylogenetic analyses identified the alga as Barranca multiflagellata gen. et sp. nov. (Barrancaceae fam. nov., Chaetophorales, Chlorophyceae). Moreover, the Chaetophoraceae Greville, 1824 was emended and a new family, Uronemataceae (fam. nov.) erected. The discovery of Barrancaceae fam. nov. highlights the importance of investigating nonconventional habitats to explore microalgal diversity. The reproductive versatility demonstrated by Barranca suggests adaptation to a semiterrestrial habitat with large fluctuations in water availability.

Anatomy of the leaf and bark of Warburgia salutaris (Canellaceae), an important medicinal plant from South Africa

Bark and leaves of Warburgia salutaris are commonly used in traditional and modern herbal medicine but there are no published anatomical descriptions that can be used in pharmacognosy or in comparative anatomy. Descriptions of salient features are presented, showing that a combination of anatomical characters is of diagnostic value. Leaf material can be identified by the absence of trichomes and the presence of translucent secretory cells, thick adaxial cuticles, numerous small druse crystals in the epidermal cells, scattered large druses and mesophyll cells with brown contents. Bark is similarly characterized by the combination of secretory cells, druses, parenchyma cells with brown contents, thin-walled fibre-like sclereids and compound sieve plates located on the lateral walls and oblique cross walls of the sieve tubes.