Variación de rasgos del xilema secundario de Bulnesia retama (Zygophyllaceae) a lo largo de un gradiente de aridez en el centro-oeste de Argentina

The study of secondary xylem of Bulnesia retama along an aridity gradient allowed finding variations among different xylem cell types that can be used to predict tolerance of this species to aridity. The aim of this work was to carry out an anatomical description of the secondary xylem through cross sections, to analyse the variation of traits considered to be important for survival in arid environments, such as the percentage of vessels, fibres and parenchyma, fibre wall thickness, and wood density. The samples were obtained from primary branches of plants from four locations along an aridity gradient (Médanos Grandes, Bermejo, Marayes and Chepes, San Juan and La Rioja provinces, Argentina). Cross sections were observed with optical microscope and resulting digital images were analysed with ImageJ software. The results indicate that vessels are small, numerous and diagonally distributed, axial parenchyma is apotracheal diffuse. A significant increase in total fibre area and a decrease in parenchyma area with increases in aridity were observed. Total vessel area did not show any changes, while fibre wall thickness increased slightly with aridity. These traits suggest that B. retama has a highly drought-tolerant wood showing phenotypic plasticity along the aridity gradient, also registering a high-density xeromorphic wood.

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Nanotubular Oxide Layer Formed on Helix Surfaces of Dental Screw Implants

Coatings ◽

10.3390/coatings11020115 ◽

2021 ◽

Vol 11 (2) ◽

pp. 115 ◽

Cited By ~ 1

Author(s):

Magdalena Jażdżewska ◽

Michał Bartmański

Keyword(s):

Oxide Layer ◽

Cross Sections ◽

Surface Coverage ◽

Artificial Saliva ◽

Corrosion Current ◽

Optical Microscope ◽

Significant Difference ◽

Helix Surfaces ◽

Future Work ◽

Oxidation Parameters

Surface modification is used to extend the life of implants. To increase the corrosion resistance and improve the biocompatibility of metal implant materials, oxidation of the Ti-13Nb-13Zr titanium alloy was used. The samples used for the research had the shape of a helix with a metric thread, with their geometry imitating a dental implant. The oxide layer was produced by a standard electrochemical method in an environment of 1M H3PO4 + 0.3% HF for 20 min, at a constant voltage of 30 V. The oxidized samples were analyzed with a scanning electron microscope. Nanotubular oxide layers with internal diameters of 30–80 nm were found. An analysis of the surface topography was performed using an optical microscope, and the Sa parameter was determined for the top of the helix and for the bottom, where a significant difference in value was observed. The presence of the modification layer, visible at the bottom of the helix, was confirmed by analyzing the sample cross-sections using computed tomography. Corrosion tests performed in the artificial saliva solution demonstrated higher corrosion current and less noble corrosion potential due to incomplete surface coverage and pitting. Necessary improved oxidation parameters will be applied in future work.

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Molecular characteristics and spatial distribution of adult human corneal cell subtypes

Scientific Reports ◽

10.1038/s41598-021-94933-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ann J. Ligocki ◽

Wen Fury ◽

Christian Gutierrez ◽

Christina Adler ◽

Tao Yang ◽

...

Keyword(s):

Single Cell ◽

Rna Sequencing ◽

Cross Sections ◽

Cell Types ◽

Marker Genes ◽

Molecular Characteristics ◽

Transcriptional Level ◽

Human Cornea ◽

Adult Human ◽

And Migration

AbstractBulk RNA sequencing of a tissue captures the gene expression profile from all cell types combined. Single-cell RNA sequencing identifies discrete cell-signatures based on transcriptomic identities. Six adult human corneas were processed for single-cell RNAseq and 16 cell clusters were bioinformatically identified. Based on their transcriptomic signatures and RNAscope results using representative cluster marker genes on human cornea cross-sections, these clusters were confirmed to be stromal keratocytes, endothelium, several subtypes of corneal epithelium, conjunctival epithelium, and supportive cells in the limbal stem cell niche. The complexity of the epithelial cell layer was captured by eight distinct corneal clusters and three conjunctival clusters. These were further characterized by enriched biological pathways and molecular characteristics which revealed novel groupings related to development, function, and location within the epithelial layer. Moreover, epithelial subtypes were found to reflect their initial generation in the limbal region, differentiation, and migration through to mature epithelial cells. The single-cell map of the human cornea deepens the knowledge of the cellular subsets of the cornea on a whole genome transcriptional level. This information can be applied to better understand normal corneal biology, serve as a reference to understand corneal disease pathology, and provide potential insights into therapeutic approaches.

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Deformation distortions of geometric form tube blanks in the process of drilling holes

10.36652/1813-1336-2021-17-3-104-110 ◽

2021 ◽

pp. 104-110

Author(s):

A.N. Isaev ◽

S.V. Vlaskin ◽

V.A. Lebedev ◽

M.D. Gavrilenko

Keyword(s):

Stress State ◽

Wall Thickness ◽

Cross Sections ◽

Theoretical Studies ◽

Geometric Form ◽

Axisymmetric Stress ◽

Axisymmetric Stress State ◽

Elastic Plastic ◽

The Cross

The influence of deviations of the shape of the cross-sections of pipes from roundness on the axisymmetric stress state and taking this factor into account in theoretical studies and methods for solving problems of mandrel drilling in the elastic-plastic mode are considered. The features of the choice of tubular blanks, which help to reduce the unevenness of deformation and increase the accuracy of processing in the process of mandrel drilling, are revealed. Recommendations are given for eliminating the variance in wall thickness of blanks at the stage of their preparation for the mandrel operation.

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Resilience aspects of woody plant species at the passage of fire: case of Quercus coccifera in Tlemcen Mountains (Algeria)

Lebanese Science Journal ◽

10.22453/lsj-021.2.119-128 ◽

2020 ◽

Vol 21 (2) ◽

pp. 119-128

Author(s):

Asma Rafa ◽

◽

Mohamed Berrichi ◽

Ahmed Haddad ◽

◽

...

Keyword(s):

Heat Conduction ◽

Porous Structure ◽

Root System ◽

Cross Sections ◽

Woody Plant ◽

Secondary Xylem ◽

Woody Species ◽

Average Diameter ◽

Quercus Coccifera ◽

Pyrolysis Gases

In this study, on the aspects of the resilience of woody species to the passage of fire, we wanted to test the alveolar specificity represented by the size of the pores of the secondary xylem of the root system in Quercus coccifera L., Pore size assessment is based on measuring 100 pores in cross sections, from the roots of 10 shrubs. The aim of this study is to explain how the roots can maintain their vitality after passing a fire and thus guarantee regeneration. In addition to the vigor of the root system of this species, the release of pyrolysis gases and the propagation of heat by conduction are provided by the porosity of the material. The results show that the pores are qualified as “fine” in the initial wood with an average diameter of 83.35 µm. In final wood, they are "very thin" with 42.30 µm in diameter. The absence of oxygen and the less porous structure delay the combustion cycle of the root system, the roots distant from the surface are thus protected from proliferation by heat conduction and thus guarantee regeneration.

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Development of Evaluation Method for Damage of Oxidation CoNiCrAlY Coating

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.804.47 ◽

2019 ◽

Vol 804 ◽

pp. 47-51

Author(s):

Mo Chen ◽

Kodai Yoshikawa ◽

Zhen Qiang Song ◽

Shijie Zhu

Keyword(s):

Cross Sections ◽

Gas Turbines ◽

Evaluation Method ◽

Thermal Spraying ◽

Optical Microscope ◽

Thermally Grown Oxide ◽

Interfacial Damage ◽

Barrier Coating ◽

Plasma Sprayed ◽

Conicraly Coating

The bond coat plays an important role in the failure of the thermal barrier coating (TBC) system used for gas turbines [1,2]. In this research, the CoNiCrAlY coated Ni-base superalloy specimens were used for developing evaluation method for interfacial damage in the coat. Samples were exposed at 1000°C and 1100°C for up to 1000 hours. The morphology and residual stress in the thermally grown oxide (TGO) layer on the CoNiCrAlY coating were characterized by microscopic observation and luminescence spectroscope, respectively. The microstructure and damage o\n both the coating surfaces and the cross sections were observed by optical microscope and scanning electron microscope. According to the results, the low pressure plasma sprayed CoNiCrAlY coating (LPPS) showed the thinnest TGO layer and lowest residual stress.Residual stress decreased with an increase in exposure time, depending on the morphology of TGO layer. The effects of thermal spraying methods on the oxidation of yttrium in TGO layer and BC layer and its influence on interfacial damage were discussed.

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ANATOMICAL CHARACTERISATION AND VARIABILITY OF THE THISTLE CYNARA CARDUNCULUS IN VIEW OF PULPING POTENTIAL

IAWA Journal ◽

10.1163/22941932-90000362 ◽

2004 ◽

Vol 25 (2) ◽

pp. 217-230 ◽

Cited By ~ 10

Author(s):

Teresa Quilhó ◽

Jorge Gominho ◽

Helena Pereira

Keyword(s):

Wall Thickness ◽

Anatomical Variation ◽

Fibre Length ◽

Vessel Element ◽

Slight Variation ◽

Vascular Bundles ◽

Cynara Cardunculus ◽

Fibrous Sheath ◽

Fibre Wall ◽

Fibre Width

The thistle Cynara cardunculus L. is an herbaceous perennial with high productivity that is harvested annually and is a potential fibre crop for paper pulp production. The anatomical variation within stalks was studied (base, middle and top) and compared in C. cardunculus plants at different development phases. The stalk of C. cardunculus includes an epidermis, cortex and a central cylinder with fibro-vascular bundles with phloem, xylem and a fibrous sheath that is variable in arrangement and size within and between plants.At harvest, the pith represents 37% of the stalk transectional area and 7% of the total weight. There was a slight variation in quantitative features of, respectively, the three development groups studied; mean fibre length was 1.04 mm, 0.95 mm and 1.05 mm; mean fibre width was 15 μm, 16 μm and 21 μm; mean fibre wall thickness was 3.2 μm, 3.4 μm and 4.9 μm. Fibre length and width decreased within the stem from base to top, while fibre wall thickness increased. Mean vessel diameter was 22 μm and mean vessel element length 220–483 μm. In mature plants, parenchyma represents 39% of the total transectional area and fibres 25%. The proportion of fibres increases during plant development and in mature plants is highest at the stalk base.As regards anatomical features, Cynara stalks compare favourably to other annual plants and fibre biometry indicates good potential for paper sheet forming and strength properties.

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Characterization and comparison of the wood anatomical traits of plantation grown Quercus acutissima and Quercus variabilis

IAWA Journal ◽

10.1163/22941932-bja10049 ◽

2021 ◽

pp. 1-14

Author(s):

Jie Wang ◽

Shan Li ◽

Juan Guo ◽

Haiqing Ren ◽

Yurong Wang ◽

...

Keyword(s):

Wall Thickness ◽

Ring Width ◽

Value Added ◽

Lumen Diameter ◽

Membrane Thickness ◽

Quercus Acutissima ◽

Fibre Wall ◽

Growth Ring Width ◽

Cambial Age ◽

Pit Membrane

Abstract Oaks are important tree species, providing essential biomaterial for the wood industry. We characterize and compare wood anatomical traits of plantation grown Quercus acutissima Carruth. and Q. variabilis Blume to provide more detailed information to understand xylem radial growth, structure, and function, as well as differences between sapwood and heartwood, to provide data relevant for tree breeding and value-added wood utilization of oak plantations in China. In this study, radial strips were collected at breast height from the main trunk of the two species. Latewood percentage and growth ring width were investigated by X-ray densitometry and a Tree Ring Analysis System, respectively. Vessel and fibre lumen diameter, vessel and fibre wall thickness, vessel density, fibre wall thickness/diameter ratio, tissue proportions, and pit membrane thickness in between vasicentric tracheids were observed with light microscopy and electron microscopy and quantified. There were significant differences in a few wood anatomical traits between the two species: vessel wall thickness and vessel lumen diameter were higher in Q. acutissima than in Q. variabilis, while higher axial parenchyma proportion in sapwood was found in Q. variabilis than in Q. acutissima. More abundant tyloses were found in heartwood than in sapwood of both species. Our work showed the intraspecific and interspecific variation of the two species. Most differences between sapwood and heartwood must be attributed to differences in cambial age during their formation.

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A Comparison of Ultrasound Echo Intensity to MRI as a Metric for Tongue Fat Evaluation

SLEEP ◽

10.1093/sleep/zsab295 ◽

2021 ◽

Author(s):

Jason L Yu ◽

Andrew Wiemken ◽

Susan M Schultz ◽

Brendan T Keenan ◽

Chandra M Sehgal ◽

...

Keyword(s):

Cross Sections ◽

Ex Vivo ◽

Human Subjects ◽

Apnea Hypopnea Index ◽

Echo Intensity ◽

Fat Percentage ◽

Obstructive Sleep ◽

Imagej Software ◽

Fat Volume ◽

Posterior Tongue

Abstract Study Objectives Tongue fat is associated with obstructive sleep apnea (OSA). Magnetic resonance imaging (MRI) is the standard for quantifying tongue fat. Ultrasound echo intensity has been shown to correlate to fat content in skeletal muscles but has yet to be studied in the tongue. The objective of this study is to evaluate the relationship between ultrasound echo intensity and tongue fat. Methods Ultrasound coronal cross-sections of ex-vivo cow tongues were recorded at baseline and following three 1 milliliter serial injections of fat into the tongue. In humans, adults with and without OSA had submental ultrasound coronal cross-sections of their posterior tongue. Average echo intensity of the tongues (cow/human) were calculated in ImageJ software. Head and neck MRI were obtained on human subjects to quantify tongue fat volume. Echo intensity was compared to injected fat volume or MRI derived tongue fat percentage. Results Echo intensity in cow tongues showed a positive correlation to injected fat volume (rho = 0.93, p<0.001). In human subjects, echo intensity of the tongue base strongly correlated with MRI-calculated fat percentage for both the posterior tongue (rho = 0.95, p<0.001) and entire tongue (rho = 0.62, p<0.001). Larger tongue fat percentages (rho = 0.38, p=0.001) and higher echo intensity (rho = 0.27, p=0.024) were associated with more severe apnea-hypopnea index, adjusted for age, BMI, sex and race. Conclusions Ultrasound echo intensity is a viable surrogate measure for tongue fat volume and may provide a convenient modality to characterize tongue fat in OSA.

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Axial heterogeneity of rabbit cortical collecting duct

AJP Renal Physiology ◽

10.1152/ajprenal.1991.260.4.f498 ◽

1991 ◽

Vol 260 (4) ◽

pp. F498-F505

Author(s):

C. L. Emmons ◽

K. Matsuzaki ◽

J. B. Stokes ◽

V. L. Schuster

Keyword(s):

Cross Sections ◽

Cell Function ◽

Rate Coefficient ◽

Collecting Duct ◽

Lectin Binding ◽

Cell Types ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Principal Cells ◽

Inner Cortex

The rabbit cortical collecting duct (CCD) consists of three major cell types: principal cells transport K+, beta-intercalated cells absorb Cl-, and alpha-intercalated cells secrete H+. We used functional and histological methods to assess axial distribution of these cell types along rabbit CCD. In perfused CCDs, lumen-to-bath Rb+ rate coefficient (an index of principal cell K+ transport) was not different in tubules from outer cortex (1 mm from renal surface) compared with those from inner cortex (2 mm from renal surface), suggesting that principal cell function is homogeneous along the CCD. In contrast, Cl- rate coefficient (a measure of beta-intercalated cell function) was twice as high in CCDs from outer compared with inner cortex, suggesting heterogeneity of beta-intercalated cells along the CCD. To further investigate these regional differences, we fixed and embedded kidneys and identified three cell types in CCD cross sections using carbonic anhydrase staining and peanut lectin binding. Comparing tubule cross sections from outer with those from inner cortex, we found no axial difference in the fraction of cells that were either principal cells (64%) or total (lectin binding and nonlectin binding) intercalated cells (36%). However, the lectin-binding intercalated cell subset was significantly increased in outer compared with inner cortex. We conclude that there is not heterogeneity of principal cells along the rabbit CCD; however, beta-cell number and function are increased in outer CCD. Collecting duct heterogeneity begins within the cortical segment.

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Geometric analysis of intrusive growth of wood fibres in Robinia pseudoacacia

IAWA Journal ◽

10.1163/22941932-20170204 ◽

2018 ◽

Vol 39 (2) ◽

pp. 191-208 ◽

Cited By ~ 2

Author(s):

Anna B. Wilczek ◽

Muhammad Iqbal ◽

Wieslaw Wloch ◽

Marcin Klisz

Keyword(s):

Secondary Xylem ◽

Robinia Pseudoacacia ◽

Geometric Analysis ◽

Cell Types ◽

Vascular Cambium ◽

Tangential Plane ◽

Intrusive Growth ◽

Thin Sections ◽

Growing Cell ◽

Vessel Elements

ABSTRACTAll cell types of the secondary xylem arise from the meristematic cells (initials) of the vascular cambium and grow under mechanical constraints emerging from the circular-symmetrical geometry that characterises many tree trunks. The course of intrusive growth of cambial initials has been elucidated, but is yet to be described in the case of xylem fibres. This study explains the geometry of intrusive growth of the secondary xylem fibres in the trunk ofRobinia pseudoacacia.Long series of serial semi-thin sections of the vascular cambium and the differentiating secondary xylem were analysed. Since fibres grow in close vicinity to expanding cells of the derivatives of the vascular cambium, we assumed that they have similar growth conditions. Dealing with the cylindrical tissue of the vascular cambium in a previous study, we used a circularly symmetrical equation for describing the growth mechanism of cambial initials. Like the cambial initials, some of the cambial derivatives differentiating into the various cell types composing the secondary xylem also exhibit intrusive growth between the tangential walls of adjacent cells. As seen in cross sections of the cambium, intrusively growing initials form slanted walls by a gradual transformation of tangential (periclinal) walls into radial (anticlinal) walls. Similarly, the intrusive growth of xylem fibres manifests initially as slants, which are formed due to axial growth of the growing cell tips along the tangential walls of adjacent cells. During this process, the tangential walls of adjacent cells are partly separated and dislocated from the tangential plane. The final shape of xylem fibres, or that of vessel elements and axial parenchyma cells, depends upon the ratio of their intrusiveversussymplastic growths in the axial, circumferential and radial directions.

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