Number Of Lamellae Research Articles

Incorporation of interfacial roughness into recursion matrix formalism of dynamical X-ray diffraction in multilayers and superlattices.

Diffraction in multilayers in the presence of interfacial roughness is studied theoretically, the roughness being considered as a transition layer. Exact (within the framework of the two-beam dynamical diffraction theory) differential equations for field amplitudes in a crystalline structure with varying properties along its surface normal are obtained. An iterative scheme for approximate solution of the equations is developed. The presented approach to interfacial roughness is incorporated into the recursion matrix formalism in a way that obviates possible numerical problems. Fitting of the experimental rocking curve is performed in order to test the possibility of reconstructing the roughness value from a diffraction scan. The developed algorithm works substantially faster than the traditional approach to dealing with a transition layer (dividing it into a finite number of thin lamellae). Calculations by the proposed approach are only two to three times longer than calculations for corresponding structures with ideally sharp interfaces.

Reconciling phylogenetic and morphological trends in North American Mammuthus

The morphology of mammoth upper third permanent molars (M3) is used to address regional- and continental-scale patterns in the structure of mammoth populations. Recent refinements to the understanding of Mammuthus phylogenetic diversity south of the Laurentide ice show extensive overlap between regional populations. We assess the underlying geographic structure in Mammuthus tooth morphology in light of these new genetic data. Comparison of regional trends in dental morphology show a single, morphologically variable, population of Mammuthus was present in North America during the Wisconsin glaciation. Within this population, there are no significant differences in degree of hypsodonty or molar shape however, there is a geographic pattern of lower enamel:dentin ratios in Mammuthus from the Channel Islands, West Coast, and Southwest/Mexico as measured by the number of molar lamellae and the standardized thickness of lamellae. These results contrast with historical perspectives of Mammuthus population structure suggesting at least four species of North American mammoths but are consistent with recent phylogeographic analyses of mitochondrial ancient DNA.

Effects of plant density on the photosynthetic and chloroplast characteristics of maize under high-yielding conditions.

Plant density has been recognized as a major factor determining the grain yield. The photosynthetic performance changes as the density increases. The main objective of this research was to evaluate responses of photosynthetic performance and chloroplast ultrastructure to planting densities in two summer maize (Zea mays L.) hybrids Denghai661 (DH661) and Nongda108 (ND108). DH661 was planted at densities of 30,000, 45,000, 60,000, 75,000, 90,000, 105,000, 120,000, or 135,000plantsha-1. ND108 was planted at densities of 30,000, 45,000, 60,000, 75,000, or 90,000plantsha-1. Research variables included leaf area, grain yield, chlorophyll content, leaf gas exchange parameters, number of chloroplasts, and chloroplast ultrastructure. As plant density increased, chlorophyll a and b content significantly decreased; carotenoids initially decreased and then increased; the net photosynthetic rate during each growth period significantly decreased; the membrane structure of mesophyll cells was gradually damaged; the number of chloroplasts significantly decreased; the external form of chloroplasts shifted from long and oval to elliptical or circular; the number of grana significantly decreased, while the number of grana lamellae increased; grana gradually became hypogenetic and eventually dissolved; plot yield increased; and yield per plant significantly decreased. The yield per plant of DH661 at 135,000plantsha-1 and that of ND108 at 90,000plantsha-1 decreased by 65.8 and 42.5%, respectively, compared with those at 30,000plantsha-1.

Lamellar and spherulitic crystallization of poly(s-2-hydroxybutanoic acid) and its stereocomplexes

Crystallization kinetics of poly (S-2-hydroxybutanoic acid) [P(S2HB)] and P(S2HB)/P (R2HB) stereocomplexes were investigated by in situ atomic force microscopy, polarized optical microscopy, and differential scanning calorimetry. For the homopolymer, an equilibrium melting temperature Tm° of 130.3 °C is obtained according to the Hoffman-Weeks method. In the case of thin films of 50 nm in thickness, a large number of edge-on lamellae form rapidly on the edge of the scratch line induced by the AFM tip. The edge-on lamellae change their orientation to flat-on lamellae at crystallization temperatures equal or higher than 75 °C. The lamellar and radial growth rates exhibit a bell-shaped temperature dependence with a maximum around 400 ± 50 nm/min at a crystallization temperature of 77 ± 2 °C, in contrast to the stereocomplexes whose growth rates peak at 19.6 μm/min. Analysis of the growth rates using the Lauritzen-Hoffman model shows that crystallization of homopolymers and stereocomplexes occurs in Regime II, with an end surface free energy σe of 6.2 × 10−2 J/m2 in the first case and 7.6–8.5 × 10−2 J/m2 in the second, and work of chain folding q between 18 and 24 kJ/mol for the homopolymer and 26–30 kJ/mol for the stereocomplexes, which is in the range of moderately stiff chains without bulky side-groups.

A new species of the genus Typhlamphiascus (Copepoda, Harpacticoida, Miraciidae) from the South China Sea

A new species, Typhlamphiascus tuerkayi sp. nov. (Copepoda, Harpacticoida, Miraciiidae), is described from specimens collected in the South China Sea. This new species differs from its congeners by the combined characters of the number of chitinous lamellae on the male P1, the apomorphic setal formulae of the swimming legs, and the setal number on P5. The new species is most similar to T. ovale Wells & Rao, 1987 and T. higginsi Chullasorn, 2009. It differs from the latter two species by the following features: the caudal ramus about three times as long as broad, P2 exp-3 with three outer spines, P3 enp-3 with two inner setae, P5 basoendopod in the female with four setae, P5 exopod in the female about three times as long as its greatest width, antennule of male 9-segmented, the inner edge of the basis in male P1 with eight chitinous lamellae, P5 exopod in male with four setae.

Circumscription of species in the Hodophilus foetens complex (Clavariaceae, Agaricales) in Europe

Four European Hodophilus species with an odour similar to naphthalene, a strong unpleasant odour similar to that of mothballs, are recognized based on sequence and/or morphological data. The traditional concept defines Ho. foetens as the only Hodophilus species with a naphthalene odour in Europe. This name is now assigned to one of the studied species based on morphological examination of the holotype specimen. A recently collected specimen is proposed as the epitype. The other three species with a naphthalene odour are described here as new: Ho. pallidus, Ho. subfoetens and Ho. tenuicystidiatus. They are distinguishable in the field based on a combination of lamellae number and colour of basidiomata. All four species are grouped in the Ho. foetens superclade, one of two superclades, together with the Ho. micaceus superclade, in the genus Hodophilus. All are different species from North American taxa with a naphthalene-like odour recognised in a previous study. The Ho. foetens superclade also includes one species identified as Ho. atropunctus that does not have a distinctive odour. The type collection of Ho. albofloccipes, a recently described European species with a naphthalene odour, is placed together with some collections without a distinctive odour in the Ho. micaceus superclade.

Characterization, virulence and pathology of Flavobacterium sp. KG3 associated with gill rot in carp, Catla catla (Ham.)

“Gill rot” caused by the Gram negative, long, rod shaped bacterium Flavobacterium sp. in a sewage fed farm growing Indian major carps in West Bengal, India, is described. The phenotypic and molecular characteristics, virulence and pathology of Flavobacterium sp. strain KG3 are also documented. The infected catla Catla catla had cutaneous haemorrhages, white patches on body and gill, gill rot and excess mucus secretion. On selective cytophaga agar, the isolate produced non-rhizoid yellow pigmented colonies. Phylogenetically, the strain KG3 was distinctly different from the closely related type strains of Flavobacterium species, though it branched with type strain F. hydatis DSM 2063 (NCBI accession number AM230487) with low node value. Histologically, the naturally infected catla gills showed cartilaginous tissue inflammation, mucus secretion, necrosis of gill filament with associated reduction in the number of lamellae per filament, obliteration of interlamellar water channels, and fusion of lamellae. Catla catla fingerlings experienced about 57% moralities within 5days of abrasion and immersion in a bath containing 4.7×106Flavobacterium sp. cells/mL. The abraded and unchallenged fingerlings recorded 20% mortality in 3days. These results demonstrated the virulence of Flavobacterium sp. in catla especially during the winter season, which warrants its management measures. Statement of relevanceFlavobacterium spp. are emerging as major pathogens of Indian freshwater fish. They can cause chronic mortalities in fish at low water temperature. Correct diagnosis and understanding the pathology would help manage flavobacterial infection in fish.

Effects of Waterlogging on Leaf Mesophyll Cell Ultrastructure and Photosynthetic Characteristics of Summer Maize.

A field experiment was performed to study the effects of waterlogging on the leaf mesophyll cell ultrastructure, chlorophyll content, gas exchange parameters, chlorophyll fluorescence, and malondialdehyde (MDA) content of summer maize (Zea mays L.) hybrids Denghai605 (DH605) and Zhengdan958 (ZD958). The waterlogging treatments were implemented for different durations (3 and 6 days) at the third leaf stage (V3), the sixth leaf stage (V6), and the 10th day after the tasseling stage (10VT). Leaf area index (LAI), chlorophyll content, photosynthetic rate (Pn), and actual photochemical efficiency (ΦPSII) were reduced after waterlogging, indicating that waterlogging significantly decreased photosynthetic capacity. The chloroplast shapes changed from long and oval to elliptical or circular after waterlogging. In addition, the internal structures of chloroplasts were degenerated after waterlogging. After waterlogging for 6 d at V3, the number of grana and grana lamellae of the third expanded leaf in DH605 were decreased by 26.83% and 55.95%, respectively, compared to the control (CK). Those in ZD958 were reduced by 30.08% and 31.94%, respectively. Waterlogging increased MDA content in both hybrids, suggesting an impact of waterlogging on membrane integrity and thus membrane deterioration. Waterlogging also damaged the biological membrane structure and mitochondria. Our results indicated that the physiological reactions to waterlogging were closely related to lower LAI, chlorophyll content, and Pn and to the destruction of chloroplast ultrastructure. These negative effects resulted in the decrease of grain yield in response to waterlogging. Summer maize was the most susceptible to damage when waterlogging occurred at V3, followed by V6 and 10VT, with damage increasing in the wake of waterlogging duration increasing.

Monoclonal gammopathy of undeterminated significance and endoneurial IgG deposition

Background:Monoclonal gammopathy of undeterminated significance is the most common form of plasma cell dyscrasia, usually considered as benign. In rare cases it may have a malignant course, sometimes limited to an organ such as peripheral nerves.Methods:We describe clinical, electrophysiological and pathological findings in a patient presenting a immunoglobulin G (IgG) paraproteinemic polyneuropathy clinically mimicking a chronic inflammatory demyelinating polyneuropathy.Results:Immuno-electron microscopy (immune-EM) demonstrated that the widenings of the myelin lamellae resulted from the infiltration of IgG between a significant number of myelin lamellae (with absence of inflammatory cells in the epineurium, endoneurium, and perineurium, and the lack signs of vasculitis). This patient was finally treated successfully with lenalidomide then mycophenolate mofetil.Conclusions:In polyneuropathies associated to a monoclonal gammopathy, a nerve biopsy may clinch the diagnosis. Immuno-EM may be required to determine the role of the pathological immunoglobulin in the destruction of the peripheral nerve parenchyma. Diagnosis of such a direct involvement of peripheral nerve can endorse more aggressive treatment of real efficiency.

PEG-mediated hydrothermal synthesis of hierarchical microspheres of MoS2 nanosheets and their potential for lubrication application

Lamellar-structured nanomaterials are gaining large interest for tribological applications owing to their remarkable mechanical and low shearing properties. Herein, polyethylene glycol (PEG)-mediated hierarchical microspheres of MoS2 nanosheets are synthesized by a facile and single-step hydrothermal reduction of ammonium molybdate in the presence of thiourea. The PEG functions as a soft templating material and provides hierarchical microspheres of MoS2 nanosheets. Detailed chemical and microstructural features of hierarchical microspheres of MoS2 nanosheets are probed by FTIR, XPS, Raman, XRD, TGA, FESEM, and HRTEM analyses. Each nanosheet of MoS2 microspheres is composed of limited number (10–20) of atomic-thick lamellae as deduced from HRTEM images. The MoS2 microspheres, as additive provide significantly improved lubrication properties for steel tribo-pair by reducing the friction (∼21%) and the wear (42%) compared to that of fully formulated 10W40 lubricant. The elemental mapping of worn surfaces revealed the deposition of MoS2 nanosheets on the contact-interfaces. The improved lubrication properties are attributed to collective effect of deposition of delaminated MoS2 lamellae on the contact interfaces, low shearing and high mechanical strength of MoS2 nanosheets.

Modelling the failure precursor mechanism of lamellar fibrous tissues, example of the annulus fibrosus

The aims of this study were to assess the damage and failure strengths of lamellar fibrous tissues, such as the anterior annulus fibrosus (AF), and to develop a mathematical model of damage propagation of the lamellae and inter-lamellar connections. This level of modelling is needed to accurately predict the effect of damage and failure induced by trauma or clinical interventions. 26 ovine anterior AF cuboid specimens from 11 lumbar intervertebral discs were tested in radial tension and mechanical parameters defining damage and failure were extracted from the in-vitro data. Equivalent 1D analytical models were developed to represent the specimen strength and the damage propagation, accounting for the specimen dimensions and number of lamellae. Model parameters were calibrated on the in-vitro data. Similar to stiffness values reported for other orientations, the outer annulus was found stronger than the inner annulus in the radial direction, with failure at higher stress values. The inner annulus failed more progressively, showing macroscopic failure at a higher strain value. The 1D analytical model of damage showed that lamellar damage is predominant in the failure mechanism of the AF. The analytical model of the connections between lamellae allowed us to represent separately damage processes in the lamellae and the inter-lamellar connections, which cannot be experimentally tested individually.

The Ross procedure: biomechanical properties of the pulmonary artery according to aortic valve phenotype.

The aim of this study is to determine whether patients undergoing the Ross procedure with bicuspid aortic valves have pulmonary artery biomechanical properties different from those with tricuspid valves. Thirty-two pulmonary arteries and 20 aortas were obtained from patients undergoing the Ross procedure at the time of surgery, from a cohort of 32 patients. The aortic valve was tricuspid in 5 patients (16%), bicuspid in 18 patients (56%) and unicuspid in 9 patients (28%). Histological analysis and ex vivo equi-biaxial tensile testing completed within 8 hours of surgery were used to evaluate differences in patient groups and between the pulmonary artery and the ascending aorta. There was no difference in thickness among pulmonary arteries when compared according to aortic valve phenotype (P = 0.94). There was no difference in the tensile tissue properties among aortas and pulmonary arteries when compared according to aortic valve phenotype, in either the circumferential or longitudinal axis. When compared according to the main surgical indication, pulmonary artery walls from patients with pure aortic regurgitation were less stiff than their counterparts (aortic regurgitation: 0.055 ± 0.037 MPa, aortic stenosis: 0.103 ± 0.051 MPa, mixed disease: 0.110 ± 0.044 MPa and aortic valve endocarditis: 0.216 ± 0.033 MPa, P = 0.002). There was no difference in the number of elastic lamellae in pulmonary artery specimens from the three different aortic valve phenotypes, as well as in the aortic specimens. No significant differences were observed in the biomechanical properties of pulmonary arteries when compared according to aortic valve phenotype.

Influence of Lamellar Thickness on Strength and Stiffness of Glued Laminated Timber Beams of Pinus oocarpa

Glued laminated timber is a structural engineered product that requires precision and strict quality control in its manufacture. For ensure that produced elements properties are in compliance with regulatory requirements, final product must be tested under laboratory conditions. Determining factors in final glulam pieces cost are the type and the quantity of adhesive used in structural elements manufacture. This study aimed to investigate, aided by three point static bending tests and variance analysis (ANOVA), influence of glue lines (3, 5, 7) and lamellae (4, 6, 8) on strength (MOR) and stiffness (MOE) properties of glulam beams manufactured with <i>Pinus</i><i>oocarpa</i> (CCA treated) and bonded with Phenol Resorcinol resin (Cascophen RS-216-M). These beams presented nominal dimensions 90mm wide; 100mm height; and 1350mm length. For 100 mm fixed height, three beams configurations were tested (a) with four lamellae of 25 mm (3 glue lines); with 6 lamellae of 16,7 mm (5 glue lines) and 8 lamellae of 12.5 mm each (7glue lines), being fabricated 6 beams for experimental condition. In addition to investigating influence of glue lines and lamellae number, possibility of estimating MOE and MOR based on apparent density was also evaluated. ANOVA results showed no significance about glue lines number (or lamellae thickness) in strength and stiffness values, implying, for economic reasons, be configuration with four 25mm lamellae the best among tested beams. From regressions, apparent density was only significant in MOE estimating (R<SUP>2</SUP> = 46.90%), indicating not be possible to estimate the stiffness and strength values of the glued laminated timber evaluated by the apparent density.

Evaluating evolutionary pressures and phylogenetic signal in earthworms: a case study - the number of typhlosole lamellae in Hormogastridae (Annelida, Oligochaeta)

Rarely have phylogenetic comparative methods been used to study the correlation between phenotypic traits and environmental variables in invertebrates. With the widespread convergence and conservativeness of the morphological characters used in earthworms, these comparative methods could be useful to improve our understanding of their evolution and systematics. One of the most prominent morphological characters in the family Hormogastridae, endemic to Mediterranean areas, is their multilamellar typhlosole, traditionally thought to be an adaptation to soils poor in nutrients. We tested the correlation of body size and soil characteristics with the number of typhlosole lamellae through a phylogenetic generalized least squares (PGLS) analysis. An ultrametric phylogenetic hypothesis was built with a 2580-bp DNA sequence from 90 populations, used in combination with three morphological and 11 soil variables. The best-supported model, based on the Akaike information criterion, was obtained by optimizing the parameters lambda (λ), kappa (κ), and delta (δ). The phylogenetic signal was strong for the number of typhlosole lamellae and average body weight, and was lower for soil variables. Increasing body weight appeared to be the main evolutionary pressure behind the increase in the number of typhlosole lamellae, with soil texture and soil richness having a weaker but significant effect. Information on the evolutionary rate of the number of typhlosole lamellae suggested that the early evolution of this character could have strongly shaped its variability, as is found in an adaptive radiation. This work highlights the importance of implementing the phylogenetic comparative method to test evolutionary hypotheses in invertebrate taxa.

Application of stochastic finite element approaches to wood-based products

Due to the natural growing process of wood, the mechanical properties of wooden boards are subject to high variability, mainly introduced by knots and the resulting deviation of the wood fibre directions around them. This variability has a great impact on the serviceability limit state performance of wood-based products, such as glued-laminated timber, and thus should be considered within design concepts. Numerous applications of random process models for numerically representing the fluctuation of the mechanical properties along wooden boards can be found in the literature. But, the corresponding mechanical probabilistic investigation, however, is limited almost exclusively to Monte Carlo simulations so far. For this reason, the focus of this work is laid on alternative probabilistic approaches, in particular the perturbation and the spectral stochastic finite element method. Both methods are combined with several discretization methods for the random process, programmed in a consistent environment, and compared to the Monte Carlo simulation, regarding computational effort as well as quality of results. For this purpose, the second-order moments (mean and standard deviation) of the system response of a glued-laminated timber beam with random lamination stiffness are computed. The performance of the different approaches is compared and, in particular, the influence of the variability of the ‘raw’ material on the structural response is shown. Well-known effects, such as the decrease in the variability of effective properties of GLT with increasing number of lamellas, are numerically reproduced and quantified. Moreover, a significant influence of the correlation length, specifying the rate of material property fluctuation within each lamella, on the effective stiffness of the resulting glued-laminated timber beams is demonstrated.

Gross morphology and histology of the olfactory organ of the Greenland shark Somniosus microcephalus

The Greenland shark (Somniosus microcephalus) is the largest predatory fish in Arctic waters. Knowledge of the fundamental biology and ecological role of the Greenland shark is limited, and the sensory biology of the Greenland shark has been poorly studied. Given the potential relevant contribution of chemoreception to the sensory capability of the Greenland shark to forage and navigate in low-light environments, we examined the architecture of the peripheral olfactory organ (the olfactory rosette) through morphological, histological and immunohistochemical assays. We found that each olfactory rosette consists of a small number of lamellae (22) associated with a relatively high surface area of the olfactory epithelium. The general organization of the epithelium is similar to that described for other elasmobranchs. However, details that have emerged concerning the cell type composition (absence of crypt neurons, presence of unusually large cells along the olfactory fiber bundles) deserve further investigation. Overall, the structure of the olfactory rosette suggests a well-developed olfactory capability for the Greenland shark coherent with a bentho-pelagic lifestyle.

Finite element simulation and analytical modeling of 3D multi scale diffusion in nanocomposites with permeable stacks

This work is aimed to study the mass transport in 3D nanocomposites, characterized by the presence of permeable lamellar stacks, by means of finite element (FE) analysis. To this purpose, a geometric model was developed, based on a random distribution of non-interpenetrating stacks, each one made of regularly spaced platelets, which are considered representative of an intercalated nanocomposite. The morphological features of the stacks are the number of lamellae and the thickness of lamellar galleries, which determine the thickness, and therefore the aspect ratio. FE simulation results showed the relevance of diffusion within stack, and therefore the unsuitableness of the assumption of stack impermeability. The diffusion behavior of nanocomposites made of permeable stacks was modeled by considering the probability of collision of diffusing particles on the stack surface. For a random orientation of stacks, the developed analytical model showed an excellent agreement with the FE simulation results. It was shown that other analytical models found in literature are not able to capture the dependence of diffusivity on the morphology of intercalated nanocomposites. The developed analytical model allowed estimating the error arising from the assumption of impermeable stacks in the estimation of nanofiller aspect ratio from experimental diffusivity data.

Dietary saffron reduced the blood pressure and prevented remodeling of the aorta in L-NAME-induced hypertensive rats.

The aim of this study was to investigate the effects of nutritional saffron (Crocus sativus L.) stigma hydroalcoholic extract on blood pressure (BP) and histology of the aorta in normotensive and hypertensive rats. Saffron (200 mg/kg/day) was given orally for 5 weeks to normotensive and hypertensive rats. Hypertension was induced by NG-nitro-L-arginine methyl ester (L-NAME; 40 mg/kg/day) administration in drinking water, and BP was measured weekly. Histological examination of the thoracic aorta included staining with hematoxylin and eosin, orcein, and periodic acid Schiff methods. Saffron had no effect on normotensive rats, but on hypertensive rats, prevented BP elevation form the third week of treatment (P<0.001). Furthermore, saffron reduced the cross-section area, media thickness, and elastic lamellae number of the aorta (P<0.05). Nutritional saffron prevented BP increases and remodeling of the aorta in hypertensive rats. It may be useful for preventing hypertension.

ARTERIAL WALL OF THE ALBINO RAT: MORPHOMETRIC STRUCTURE AND GENERAL MORPHOPHYSIOLOGY

The histological structure and some morphometric parameters referring the aortic architecture of the adult, laboratorial albino rat were focused from the three segmental parts of the aorta comprising the thoracic ascendant and thoracic descendant parts, and the abdominal infra kidneys part of aorta. This last aortic segment showed a mixed pattern from the mural building formed by similar amounts of smooth muscle cells and connective matrix elements, being represented by collagen and elastic lamellae and fibers. However a classic elastic mural pattern was verified in the thoracic segments of the rat aorta, an intermingled pattern mainly occurred between the smooth muscle cells and matrix elements in all the segments of the rat aorta. The thickness of the aortic wall showed a numeric progressive lower from the ascendant part to the abdominal distal part of aorta. Similar pattern was verified for the number of elastic lamellae, which the major lamellar number observed could be related with the luminal vortex flow observed inside the ascendant aortic part. Also the aortic diameters verified decreased progressively from the ascendant to the abdominal part of aorta.

Two new species of Cyrtodactylus (Squamata: Gekkonidae) from the karst forest of Hoa Binh Province, Vietnam.

We describe two new species of the genus Cyrtodactylus on the basis of a new reptile collection from the limestone karst forest of Hoa Binh Province, northwestern Vietnam. Cyrtodactylus otai sp. nov. from Hang Kia-Pa Co Nature Reserve and Cyrtodactylus bobrovi sp. nov. from Ngoc Son-Ngo Luong Nature Reserve can be distinguished from each other and from their congeners by their genetic distinction and morphological differences in number of precloacal pores, femoral scales, ventral scales, lamellae, subcaudals and dorsal tubercle arrangement, as well as in size and color pattern. In phylogenetic analyses, both new species are nested in a clade containing taxa from northwestern and northcentral Vietnam and northern Laos, i.e., C. bichnganae and C. cf. martini from northwestern Vietnam, C. puhuensis from northcentral Vietnam, and C. spelaeus, C. vilaphongi, and C. wayakonei from northern Laos.