scholarly journals Maize stalk stiffness and strength are primarily determined by morphological factors

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Christopher J. Stubbs ◽  
Ryan Larson ◽  
Douglas D. Cook
Keyword(s):  
Material Properties ◽  
Structural Strength ◽  
Biological Activities ◽  
Structural Parameters ◽  
Sensitivity Analyses ◽  
Bioenergy Crops ◽  
Tissue Properties ◽  
Three Point Bending ◽  
X Ray Computed ◽  
The Right

AbstractThe maize (Zea mays) stem is a biological structure that must balance both biotic and structural load bearing duties. These competing requirements are particularly relevant in the design of new bioenergy crops. Although increased stem digestibility is typically associated with a lower structural strength and higher propensity for lodging, with the right balance between structural and biological activities it may be possible to design crops that are high-yielding and have digestible biomass. This study investigates the hypothesis that geometric factors are much more influential in determining structural strength than tissue properties. To study these influences, both physical and in silico experiments were used. First, maize stems were tested in three-point bending. Specimen-specific finite element models were created based on x-ray computed tomography scans. Models were validated by comparison with experimental data. Sensitivity analyses were used to assess the influence of structural parameters such as geometric and material properties. As hypothesized, geometry was found to have a much stronger influence on structural stability than material properties. This information reinforces the notion that deficiencies in tissue strength could be offset by manipulation of stalk morphology, thus allowing the creation of stalks which are both resilient and digestible.

scholarly journals Maize Stem Buckling Failure is Dominated by Morphological Factors

2019 ◽  
Author(s):  
Christopher J Stubbs ◽  
Ryan Larson ◽  
Douglas D Cook
Keyword(s):  
In Silico ◽  
Structural Strength ◽  
Biological Activities ◽  
Bioenergy Crops ◽  
Tissue Properties ◽  
Three Point Bending ◽  
Geometric Factors ◽  
X Ray Computed ◽  
The Right

AbstractThe maize (Zea mays) stem is a biological structure that must both balance biotic and structural load bearing duties. These competing requirements are particularly relevant in the design of new bioenergy crops. With the right balance between structural and biological activities, it may be possible to design crops that are high-yielding and have digestible biomass. But increased stem digestibility is typically associated with a lower structural strength and higher propensity for lodging. This study investigates the hypothesis that geometric factors are much more influential in determining structural strength than tissue properties. To study these influences, both physical and in silico experiments were used. First, maize stems were tested in three-point bending. Specimen-specific finite element models were created based on x-ray computed tomography scans. Models were validated by comparison with in vitro data. As hypothesized, geometry was found to have a much stronger influence on structural stability than material properties. This information reinforces the notion that deficiencies in tissue strength could be offset by manipulation of stalk morphology, thus allowing the creation of stalks with are both resilient and digestible.HighlightThis study utilized physical and in silico experiments to confirm that geometric parameters are far more influential in determining stalk strength than mechanical tissue stiffnesses.

scholarly journals The effect of intramuscular fat on skeletal muscle mechanics: implications for the elderly and obese

2015 ◽  
Vol 12 (109) ◽  
pp. 20150365 ◽  
Author(s):  
Hadi Rahemi ◽  
Nilima Nigam ◽  
James M. Wakeling
Keyword(s):  
Skeletal Muscle ◽  
Material Properties ◽  
Structural Parameters ◽  
Muscle Mechanics ◽  
Base Material ◽  
Element Model ◽  
Intramuscular Fat ◽  
Muscle Performance ◽  
Muscle Quality ◽  
Tissue Properties

Skeletal muscle accumulates intramuscular fat through age and obesity. Muscle quality, a measure of muscle strength per unit size, decreases in these conditions. It is not clear how fat influences this loss in performance. Changes to structural parameters (e.g. fibre pennation and connective tissue properties) affect the muscle quality. This study investigated the mechanisms that lead to deterioration in muscle performance due to changes in intramuscular fat, pennation and aponeurosis stiffness. A finite-element model of the human gastrocnemius was developed as a fibre-reinforced composite biomaterial containing contractile fibres within the base material. The base-material properties were modified to include intramuscular fat in five different ways. All these models with fat generated lower fibre stress and muscle quality than their lean counterparts. This effect is due to the higher stiffness of the tissue in the fatty models. The fibre deformations influence their interactions with the aponeuroses, and these change with fatty inclusions. Muscles with more compliant aponeuroses generated lower forces. The muscle quality was further reduced for muscles with lower pennation. This study shows that whole-muscle force is dependent on its base-material properties and changes to the base material due to fatty inclusions result in reductions to force and muscle quality.

Novel Iodinated Hydrazide-hydrazones and their Analogues as Acetyl- and Butyrylcholinesterase Inhibitors

2020 ◽  
Vol 20 (23) ◽  
pp. 2106-2117
Author(s):  
Martin Krátký ◽  
Šárka Štěpánková ◽  
Michaela Brablíková ◽  
Katarína Svrčková ◽  
Markéta Švarcová ◽  
...  
Keyword(s):  
Biological Activities ◽  
Structural Parameters ◽  
Covalent Binding ◽  
Docking Studies ◽  
Potent Inhibition ◽  
Brain Barrier Permeability ◽  
Electric Eel ◽  
Ic50 Values ◽  
Ellman’S Method

Background: Hydrazide-hydrazones have been known as scaffold with various biological activities including inhibition of acetyl- (AChE) and butyrylcholinesterase (BuChE). Cholinesterase inhibitors are mainstays of dementias’ treatment. Objective: Twenty-five iodinated hydrazide-hydrazones and their analogues were designed as potential central AChE and BuChE inhibitors. Methods: Hydrazide-hydrazones were synthesized from 4-substituted benzohydrazides and 2-/4- hydroxy-3,5-diiodobenzaldehydes. The compounds were investigated in vitro for their potency to inhibit AChE from electric eel and BuChE from equine serum using Ellman’s method. We calculated also physicochemical and structural parameters for CNS delivery. Results: The derivatives exhibited a moderate dual inhibition with IC50 values ranging from 15.1-140.5 and 35.5 to 170.5 μmol.L-1 for AChE and BuChE, respectively. Generally, the compounds produced a balanced or more potent inhibition of AChE. N'-[(E)-(4-Hydroxy-3,5-diiodophenyl)methylidene]-4- nitrobenzohydrazide 2k and 4-fluoro-N'-(2-hydroxy-3,5-diiodobenzyl)benzohydrazide 3a were the most potent inhibitors of AChE and BuChE, respectively. Structure-activity relationships were established, and molecular docking studies confirmed interaction with enzymes. Conclusion: Many novel hydrazide-hydrazones showed lower IC50 values than rivastigmine against AChE and some of them were comparable for BuChE to this drug used for the treatment of dementia. They interact with cholinesterases via non-covalent binding into the active site. Based on the BOILEDEgg approach, the majority of the derivatives met the criteria for blood-brain-barrier permeability.

Kawasaki disease complicated by cerebral infarction

2003 ◽  
Vol 13 (1) ◽  
pp. 103-105 ◽  
Author(s):  
Kenji Suda ◽  
Masahiko Matsumura ◽  
Shigeru Ohta
Keyword(s):  
Kawasaki Disease ◽  
Cerebral Infarction ◽  
Clinical Situation ◽  
Sudden Onset ◽  
X Ray ◽  
Coronary Aneurysms ◽  
Intracoronary Thrombolysis ◽  
Tissue Plasminogen ◽  
X Ray Computed ◽  
The Right

An 8-month-old boy presented with right hemiplegia of sudden onset after 20 days of Kawasaki disease, which was not initially treated by gamma globulin. Cranial X-ray computed tomography confirmed cerebral infarction as the cause of the right hemiplegia. In subsequent weeks, he developed multiple thromboses in coronary aneurysms. He successfully underwent intracoronary thrombolysis using tissue plasminogen activator without haemorrhagic complications. Cerebral infarction as a complication of Kawasaki disease is rare, and is a difficult clinical situation to manage.

Nature of the clay - cation bond affects soil structure as verified by X-ray computed tomography

Soil Research ◽  
2012 ◽  
Vol 50 (8) ◽  
pp. 638 ◽  
Author(s):  
Alla Marchuk ◽  
Pichu Rengasamy ◽  
Ann McNeill ◽  
Anupama Kumar
Keyword(s):  
Computed Tomography ◽  
Hydraulic Conductivity ◽  
Zeta Potential ◽  
Structural Stability ◽  
Structural Parameters ◽  
Pore Connectivity ◽  
X Ray ◽  
Clay Dispersion ◽  
X Ray Computed ◽  
Cation Ratio

Non-destructive X-ray computed tomography (µCT) scanning was used to characterise changes in pore architecture as influenced by the proportion of cations (Na, K, Mg, or Ca) bonded to soil particles. These observed changes were correlated with measured saturated hydraulic conductivity, clay dispersion, and zeta potential, as well as cation ratio of structural stability (CROSS) and exchangeable cation ratio. Pore architectural parameters such as total porosity, closed porosity, and pore connectivity, as characterised from µCT scans, were influenced by the valence of the cation and the extent it dominated in the soil. Soils with a dominance of Ca or Mg exhibited a well-developed pore structure and pore interconnectedness, whereas in soil dominated by Na or K there were a large number of isolated pore clusters surrounded by solid matrix where the pores were filled with dispersed clay particles. Saturated hydraulic conductivities of cationic soils dominated by a single cation were dependent on the observed pore structural parameters, and were significantly correlated with active porosity (R2 = 0.76) and pore connectivity (R2 = 0.97). Hydraulic conductivity of cation-treated soils decreased in the order Ca > Mg > K > Na, while clay dispersion, as measured by turbidity and the negative charge of the dispersed clays from these soils, measured as zeta potential, decreased in the order Na > K > Mg > Ca. The results of the study confirm that structural changes during soil–water interaction depend on the ionicity of clay–cation bonding. All of the structural parameters studied were highly correlated with the ionicity indices of dominant cations. The degree of ionicity of an individual cation also explains the different effects caused by cations within a monovalent or divalent category. While sodium adsorption ratio as a measure of soil structural stability is only applicable to sodium-dominant soils, CROSS derived from the ionicity of clay–cation bonds is better suited to soils containing multiple cations in various proportions.

Dependence of Mechanical Behavior of the Murine Tail Disc on Regional Material Properties: A Parametric Finite Element Study

2005 ◽  
Vol 127 (7) ◽  
pp. 1158-1167 ◽  
Author(s):  
Adam H. Hsieh ◽  
Diane R. Wagner ◽  
Louis Y. Cheng ◽  
Jeffrey C. Lotz
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Nucleus Pulposus ◽  
Material Properties ◽  
Mechanical Response ◽  
Swelling Pressure ◽  
Transient Behavior ◽  
Sensitivity Analyses ◽  
Intact Mouse

In vivo rodent tail models are becoming more widely used for exploring the role of mechanical loading on the initiation and progression of intervertebral disc degeneration. Historically, finite element models (FEMs) have been useful for predicting disc mechanics in humans. However, differences in geometry and tissue properties may limit the predictive utility of these models for rodent discs. Clearly, models that are specific for rodent tail discs and accurately simulate the disc’s transient mechanical behavior would serve as important tools for clarifying disc mechanics in these animal models. An FEM was developed based on the structure, geometry, and scale of the mouse tail disc. Importantly, two sources of time-dependent mechanical behavior were incorporated: viscoelasticity of the matrix, and fluid permeation. In addition, a novel strain-dependent swelling pressure was implemented through the introduction of a dilatational stress in nuclear elements. The model was then validated against data from quasi-static tension-compression and compressive creep experiments performed previously using mouse tail discs. Finally, sensitivity analyses were performed in which material parameters of each disc subregion were individually varied. During disc compression, matrix consolidation was observed to occur preferentially at the periphery of the nucleus pulposus. Sensitivity analyses revealed that disc mechanics was greatly influenced by changes in nucleus pulposus material properties, but rather insensitive to variations in any of the endplate properties. Moreover, three key features of the model—nuclear swelling pressure, lamellar collagen viscoelasticity, and interstitial fluid permeation—were found to be critical for accurate simulation of disc mechanics. In particular, collagen viscoelasticity dominated the transient behavior of the disc during the initial 2200s of creep loading, while fluid permeation governed disc deformation thereafter. The FEM developed in this study exhibited excellent agreement with transient creep behavior of intact mouse tail motion segments. Notably, the model was able to produce spatial variations in nucleus pulposus matrix consolidation that are consistent with previous observations in nuclear cell morphology made in mouse discs using confocal microscopy. Results of this study emphasize the need for including nucleus swelling pressure, collagen viscoelasticity, and fluid permeation when simulating transient changes in matrix and fluid stress/strain. Sensitivity analyses suggest that further characterization of nucleus pulposus material properties should be pursued, due to its significance in steady-state and transient disc mechanical response.

scholarly journals International R&D Spillovers and Innovation Efficiency

2018 ◽  
Vol 10 (11) ◽  
pp. 3974 ◽  
Author(s):  
Jianping Liu ◽  
Kai Lu ◽  
Shixiong Cheng
Keyword(s):  
Capital Stock ◽  
Stochastic Frontier Analysis ◽  
Stochastic Frontier ◽  
Sensitivity Analyses ◽  
Frontier Analysis ◽  
Country Level ◽  
Scientific Papers ◽  
Catch Up ◽  
The Right ◽  
The Impact

The objective of this study is to examine the impact of international research and development (R&D) spillovers on innovation efficiency of specific R&D outcomes, employing the country-level panel data for 44 countries in the 1996–2013 period. Fully considering the heterogeneity of different R&D outputs, scientific papers, PCT (Patent Cooperation Treaty) patents, US patents, and domestic patents are observed separately, which enriches the angles of measuring international R&D spillovers. By applying a stochastic frontier analysis to knowledge production function, we find that foreign R&D capital stock positively contributes to the innovation efficiency of scientific papers, but suppresses the productivity of domestic patents, whereas it does not really matter for PCT or US patents. These results are robust to control for a set of institutional factors and also in sensitivity analyses. Hence, dependence on international R&D spillovers seems neither to be the right way for emerging economies to catch up, nor to be a sustainable model for developing countries to fill the technical gap. Local R&D capital stock, instead, keeps an essential contributor to all four R&D outputs, so raising internal R&D expenditure is actually the key to improving innovation level and sustainable development ability.

scholarly journals In Vitro Study of Multi-Therapeutic Properties of Thymus bovei Benth. Essential Oil and Its Main Component for Promoting Their Use in Clinical Practice

2018 ◽  
Vol 7 (9) ◽  
pp. 283 ◽  
Author(s):  
Sherif Hassan ◽  
Kateřina Berchová-Bímová ◽  
Miroslava Šudomová ◽  
Milan Malaník ◽  
Karel Šmejkal ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Clinical Practice ◽  
Essential Oil ◽  
Biological Activities ◽  
Structural Parameters ◽  
Antihypertensive Agents ◽  
Gas Chromatography Mass Spectrometry ◽  
Ic50 Values ◽  
Main Component

Thymus bovei Benth. (TB) is an important plant in the traditional medicine of the Mediterranean region. This study investigates the health-promoting properties of TB essential oil (TB-EO) for its possible use in clinical practice with regards to its cytotoxic, anti-herpes simplex virus type 2 (HSV-2), and antihypertensive (through inhibition of human angiotensin-converting enzyme; ACE) properties. The phytochemical profile of EO (99.9%) was analyzed by Gas Chromatography with Flame-Ionization Detection (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS). In this study, all biological methods were performed at the level of in vitro studies. The results showed that TB-EO exerted remarked cytotoxic properties against human cervical carcinoma cells, colon cancer cells, and lung adenocarcinoma cells with the half-maximal inhibitory concentration (IC50) values of 7.22, 9.30, and 8.62 µg/mL, respectively, in comparison with that of standard anticancer drug cisplatin with IC50 values of 4.24, 5.21, and 5.43 µg/mL, respectively. Fascinatingly, TB-EO showed very weak cytotoxicity on the healthy human fetal lung fibroblast cells with an IC50 value of 118.34 µg/mL compared with that of cisplatin (IC50 = 10.08 µg/mL). TB-EO, its main component geraniol, TB-EO combined with acyclovir (ACV) along with standard ACV, have displayed pronounced inhibitory properties against the replication of HSV-2 with the half-maximal effective concentration (EC50) values of 2.13, 1.92, 0.81 and 1.94 µg/mL, respectively, with corresponding selectivity indices (SI) 98.59, 109.38, 259.26 and 108.25, respectively. TB-EO and geraniol at a concentration of 15 µg/mL showed prominent inhibitory activities against ACE with % of inhibition 95.4% and 92.2%, respectively, compared with that of standard inhibitor captopril (99.8%; 15 µg/mL). Molecular docking studies were performed to unveil the mechanism of action of geraniol as well as structural parameters necessary for anti-HSV-2 activity (through the inhibition of HSV-2 protease) and ACE inhibition. This is the first report on the chemical composition of Egyptian TB-EO along with the above-mentioned biological activities. Our results may be considered as novel findings in the course of a search for new and active anticancer, anti-HSV-2 and antihypertensive agents, and expand the medicinal value of this plant and its phytochemicals in clinical practice.

Visuotactile Representation of Peripersonal Space: A Neural Network Study

2010 ◽  
Vol 22 (1) ◽  
pp. 190-243 ◽  
Author(s):  
Elisa Magosso ◽  
Melissa Zavaglia ◽  
Andrea Serino ◽  
Giuseppe di Pellegrino ◽  
Mauro Ursino
Keyword(s):  
Neural Network ◽  
Peripersonal Space ◽  
Sensitivity Analyses ◽  
Neurological Deficits ◽  
Inhibitory Synapses ◽  
Space Representation ◽  
Emergent Properties ◽  
Bilateral Stimulation ◽  
The Right ◽  
Parameter Values

Neurophysiological and behavioral studies suggest that the peripersonal space is represented in a multisensory fashion by integrating stimuli of different modalities. We developed a neural network to simulate the visual-tactile representation of the peripersonal space around the right and left hands. The model is composed of two networks (one per hemisphere), each with three areas of neurons: two are unimodal (visual and tactile) and communicate by synaptic connections with a third downstream multimodal (visual-tactile) area. The hemispheres are interconnected by inhibitory synapses. We applied a combination of analytic and computer simulation techniques. The analytic approach requires some simplifying assumptions and approximations (linearization and a reduced number of neurons) and is used to investigate network stability as a function of parameter values, providing some emergent properties. These are then tested and extended by computer simulations of a more complex nonlinear network that does not rely on the previous simplifications. With basal parameter values, the extended network reproduces several in vivo phenomena: multisensory coding of peripersonal space, reinforcement of unisensory perception by multimodal stimulation, and coexistence of simultaneous right- and left-hand representations in bilateral stimulation. By reducing the strength of the synapses from the right tactile neurons, the network is able to mimic the responses characteristic of right-brain-damaged patients with left tactile extinction: perception of unilateral left tactile stimulation, cross-modal extinction and cross-modal facilitation in bilateral stimulation. Finally, a variety of sensitivity analyses on some key parameters was performed to shed light on the contribution of single-model components in network behaviour. The model may help us understand the neural circuitry underlying peripersonal space representation and identify its alterations explaining neurological deficits. In perspective, it could help in interpreting results of psychophysical and behavioral trials and clarifying the neural correlates of multisensory-based rehabilitation procedures.

scholarly journals Low-Dosed X-Ray Computed Tomography Imaging by Regularized Fully Spatial Fractional-Order Perona-Malik Diffusion

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Zhiwu Liao
Keyword(s):  
Computed Tomography ◽  
Fractional Order ◽  
Low Dose ◽  
Computed Tomography Imaging ◽  
Edge Preserving ◽  
X Ray ◽  
Good Ability ◽  
X Ray Computed ◽  
The Right ◽  
Low Dose Computed Tomography

Existing fractional-order Perona-Malik Diffusion (FOPMD) algorithms used in noise suppressing suffer from undesired artifacts and speckle effect, which hamper FOPMD used in low-dosed X-ray computed tomography (LDCT) imaging. In this paper, we propose a new FOPMD method for low-dose computed tomography (LDCT) imaging, which is called regularized fully spatial FOPMD (RFS-FOPMD), whose numerical scheme is also given based on Grünwald-Letnikov derivative (G-L derivative). Here, fully spatial FOPMD represents all the integer-order derivatives (IODs) in the right hand of Perona-Malik Diffusion (PMD) which are replaced by fractional-order derivatives (FODs). Since the new scheme has advantages of both regularization and FOPMD, it has good abilities in singularities preserving while suppressing noise. Some real sinogram of LDCT are used to compare the different performances not only for some classical but also for some state-of-art diffusion schemes. These schemes include PMD, regularized PMD (RPMD), and FOPMD in (Hu et al. 2012). Experimental results show that besides good ability in edge preserving, the new scheme also has good stability for iteration number and can avoid artifacts and speckle effect with suitable parameters.

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