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1.
Proc Natl Acad Sci U S A ; 120(33): e2218869120, 2023 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-37549251

RESUMEN

In this paper, we introduce an efficient method for computing curves minimizing a variant of the Euler-Mumford elastica energy, with fixed endpoints and tangents at these endpoints, where the bending energy is enhanced with a user-defined and data-driven scalar-valued term referred to as the curvature prior. In order to guarantee that the globally optimal curve is extracted, the proposed method involves the numerical computation of the viscosity solution to a specific static Hamilton-Jacobi-Bellman (HJB) partial differential equation (PDE). For that purpose, we derive the explicit Hamiltonian associated with this variant model equipped with a curvature prior, discretize the resulting HJB PDE using an adaptive finite difference scheme, and solve it in a single pass using a generalized fast-marching method. In addition, we also present a practical method for estimating the curvature prior values from image data, designed for the task of accurately tracking curvilinear structure centerlines. Numerical experiments on synthetic and real-image data illustrate the advantages of the considered variant of the elastica model with a prior curvature enhancement in complex scenarios where challenging geometric structures appear.

2.
Proc Natl Acad Sci U S A ; 118(21)2021 05 25.
Artículo en Inglés | MEDLINE | ID: mdl-34016749

RESUMEN

Worldwide cardiovascular diseases such as stroke and heart disease are the leading cause of mortality. While guidewire/catheter-based minimally invasive surgery is used to treat a variety of cardiovascular disorders, existing passive guidewires and catheters suffer from several limitations such as low steerability and vessel access through complex geometry of vasculatures and imaging-related accumulation of radiation to both patients and operating surgeons. To address these limitations, magnetic soft continuum robots (MSCRs) in the form of magnetic field-controllable elastomeric fibers have recently demonstrated enhanced steerability under remotely applied magnetic fields. While the steerability of an MSCR largely relies on its workspace-the set of attainable points by its end effector-existing MSCRs based on embedding permanent magnets or uniformly dispersing magnetic particles in polymer matrices still cannot give optimal workspaces. The design and optimization of MSCRs have been challenging because of the lack of efficient tools. Here, we report a systematic set of model-based evolutionary design, fabrication, and experimental validation of an MSCR with a counterintuitive nonuniform distribution of magnetic particles to achieve an unprecedented workspace. The proposed MSCR design is enabled by integrating a theoretical model and the genetic algorithm. The current work not only achieves the optimal workspace for MSCRs but also provides a powerful tool for the efficient design and optimization of future magnetic soft robots and actuators.

3.
BMC Cardiovasc Disord ; 23(1): 152, 2023 03 24.
Artículo en Inglés | MEDLINE | ID: mdl-36959580

RESUMEN

BACKGROUND: The number of patients with heart disease who can benefit from treatment is continuing to increase due to the widespread use of cardiac implantable devices. Accordingly, the number of cardiac device-related infective endocarditis (CDRIE) cases has been increasing year by year. We report a very rare experience of performing an autopsy on a patient who died of CDRIE at the site of MitraClip ® implantation, which has recently been developed as a treatment option for severe mitral regurgitation. In addition to hematoxylin-eosin (H-E) staining, Elastica-Masson staining in the present case revealed destruction of all of the atrial, trabecular, fiber and myocardial layers. CASE PRESENTATION: The patient was hemodialyzed with a dialysis catheter. Hemodialysis treatment was difficult due to functional mitral regurgitation caused by cardiac dysfunction, and the MitraClip® procedure was performed. However, he subsequently developed a fever and dialyzation became difficult again, and he was admitted to the cardiology department. Echocardiography revealed a large vegetation at the site of MitraClip® implantation and a diagnosis of CDRIE was made. Guidelines recommend removal of the device and surgical intervention. However, considering the patient's general condition, a decision was made at a heart team conference to give priority to antibiotic therapy. However, the patient did not respond to antibiotic therapy and died of septic shock. CONCLUSION: To our knowledge, this is the first reported case of CDRIE and death after MitraClip® implantation that resulted in an autopsy. Furthermore, not only H-E staining but also Elastica-Masson staining was performed, and it was confirmed that there was significant valve tissue destruction. In the future, the MitraClip® procedure, even though it is minimally invasive, should be carefully considered in immunocompromised patients.


Asunto(s)
Endocarditis Bacteriana , Endocarditis , Implantación de Prótesis de Válvulas Cardíacas , Insuficiencia de la Válvula Mitral , Masculino , Humanos , Insuficiencia de la Válvula Mitral/diagnóstico por imagen , Insuficiencia de la Válvula Mitral/etiología , Insuficiencia de la Válvula Mitral/cirugía , Válvula Mitral/diagnóstico por imagen , Válvula Mitral/cirugía , Implantación de Prótesis de Válvulas Cardíacas/efectos adversos , Autopsia , Goma , Resultado del Tratamiento , Diálisis Renal , Endocarditis/complicaciones , Endocarditis/diagnóstico , Endocarditis Bacteriana/complicaciones , Endocarditis Bacteriana/diagnóstico , Catéteres , Antibacterianos
4.
Ann Bot ; 130(3): 285-300, 2022 09 19.
Artículo en Inglés | MEDLINE | ID: mdl-35452520

RESUMEN

BACKGROUND: Stomatal pores in many species are separated from the atmosphere by different anatomical obstacles produced by leaf epidermal cells, especially by sunken stomatal crypts, stomatal antechambers and/or hairs (trichomes). The evolutionary driving forces leading to sunken or 'hidden' stomata whose antechambers are filled with hairs or waxy plugs are not fully understood. The available hypothetical explanations are based mainly on mathematical modelling of water and CO2 diffusion through superficial vs. sunken stomata, and studies of comparative autecology. A better understanding of this phenomenon may result from examining the interactions between the leaf cuticle and stomata and from functional comparisons of sunken vs. superficially positioned stomata, especially when transpiration is low, for example at night or during severe drought. SCOPE: I review recent ideas as to why stomata are hidden and test experimentally whether hidden stomata may behave differently from those not covered by epidermal structures and so are coupled more closely to the atmosphere. I also quantify the contribution of stomatal vs. cuticular transpiration at night using four species with sunken stomata and three species with superficial stomata. CONCLUSIONS: Partitioning of leaf conductance in darkness (gtw) into stomatal and cuticular contributions revealed that stomatal conductance dominated gtw across all seven investigated species with antechambers with different degrees of prominence. Hidden stomata contributed, on average, less to gtw (approx. 70 %) than superficial stomata (approx. 80 %) and reduced their contribution dramatically with increasing gtw. In contrast, species with superficial stomata kept their proportion in gtw invariant across a broad range of gtw. Mechanisms behind the specific behaviour of hidden stomata and the multipurpose origin of sunken stomata are discussed.


Asunto(s)
Dióxido de Carbono , Transpiración de Plantas , Sequías , Hojas de la Planta , Estomas de Plantas , Agua
5.
Sensors (Basel) ; 22(9)2022 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-35590865

RESUMEN

This paper studies the Fast Marching Square (FM2) method as a competitive path planner for UAV applications. The approach fulfills trajectory curvature constraints together with a significantly reduced computation time, which makes it overperform with respect to other planning methods of the literature based on optimization. A comparative analysis is presented to demonstrate how the FM2 approach can easily adapt its performance thanks to the introduction of two parameters, saturation α and exponent ß, that allow a flexible configuration of the paths in terms of curvature restrictions, among others. The main contributions of the method are twofold: first, a feasible path is directly obtained without the need of a later optimization process to accomplish curvature restrictions; second, the computation speed is significantly increased, up to 220 times faster than other optimization-based methods such as, for instance, Dubins, Euler-Mumford Elastica and Reeds-Shepp. Simulation results are given to demonstrate the superiority of the method when used for UAV applications in comparison with the three previously mentioned methods.

6.
Ann Bot ; 126(1): 141-162, 2020 06 19.
Artículo en Inglés | MEDLINE | ID: mdl-32222770

RESUMEN

BACKGROUND AND AIMS: The cuticle of a limited number of plant species contains cutan, a chemically highly resistant biopolymer. As yet, the biosynthesis of cutan is not fully understood. Attempting to further unravel the origin of cutan, we analysed the chemical composition of enzymatically isolated cuticular membranes of Agave americana leaves. METHODS: Cuticular waxes were extracted with organic solvents. Subsequently, the dewaxed cuticular membrane was depolymerized by acid-catalysed transesterification yielding cutin monomers and cutan, a non-hydrolysable, cuticular membrane residue. The cutan matrix was analysed by thermal extraction, flash pyrolysis and thermally assisted hydrolysis and methylation to elucidate the monomeric composition and deduce a putative biosynthetic origin. KEY RESULTS: According to gas chromatography-mass spectrometry analyses, the cuticular waxes of A. americana contained primarily very-long-chain alkanoic acids and primary alkanols dominated by C32, whereas the cutin biopolyester of A. americana mainly consisted of 9,10-epoxy ω-hydroxy and 9,10,ω-trihydroxy C18 alkanoic acids. The main aliphatic cutan monomers were alkanoic acids, primary alkanols, ω-hydroxy alkanoic acids and alkane-α,ω-diols ranging predominantly from C28 to C34 and maximizing at C32. Minor contributions of benzene-1,3,5-triol and derivatives suggested that these aromatic moieties form the polymeric core of cutan, to which the aliphatic moieties are linked via ester and possibly ether bonds. CONCLUSIONS: High similarity of aliphatic moieties in the cutan and the cuticular wax component indicated a common biosynthetic origin. In order to exclude species-specific peculiarities of A. americana and to place our results in a broader context, cuticular waxes, cutin and cutan of Clivia miniata, Ficus elastica and Prunus laurocerasus leaves were also investigated. A detailed comparison showed compositional and structural differences, indicated that cutan was only found in leaves of perennial evergreen A. americana and C. miniata, and made clear that the phenomenon of cutan is possibly less present in plant species than suggested in the literature.


Asunto(s)
Lípidos de la Membrana , Ceras , Ésteres , Hojas de la Planta
7.
Int J Mol Sci ; 19(8)2018 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-30104475

RESUMEN

Next-generation sequencing (NGS) of the Flammulina elastica (wood-rotting basidiomycete) genome was performed to identify carbohydrate-active enzymes (CAZymes). The resulting assembly (31 kmer) revealed a total length of 35,045,521 bp (49.7% GC content). Using the AUGUSTUS tool, 12,536 total gene structures were predicted by ab initio gene prediction. An analysis of orthologs revealed that 6806 groups contained at least one F. elastica protein. Among the 12,536 predicted genes, F. elastica contained 24 species-specific genes, of which 17 genes were paralogous. CAZymes are divided into five classes: glycoside hydrolases (GHs), carbohydrate esterases (CEs), polysaccharide lyases (PLs), glycosyltransferases (GTs), and auxiliary activities (AA). In the present study, annotation of the predicted amino acid sequences from F. elastica genes using the dbCAN CAZyme database revealed 508 CAZymes, including 82 AAs, 218 GHs, 89 GTs, 18 PLs, 59 CEs, and 42 carbohydrate binding modules in the F. elastica genome. Although the CAZyme repertoire of F. elastica was similar to those of other fungal species, the total number of GTs in F. elastica was larger than those of other basidiomycetes. This genome information elucidates newly identified wood-degrading machinery in F. elastica, offers opportunities to better understand this fungus, and presents possibilities for more detailed studies on lignocellulosic biomass degradation that may lead to future biotechnological and industrial applications.


Asunto(s)
Flammulina/genética , Proteínas Fúngicas/genética , Genoma Fúngico , Bases de Datos Genéticas , Flammulina/enzimología , Proteínas Fúngicas/clasificación , Proteínas Fúngicas/metabolismo , Glicósido Hidrolasas/química , Glicósido Hidrolasas/genética , Glicósido Hidrolasas/metabolismo , Glicosiltransferasas/química , Glicosiltransferasas/genética , Glicosiltransferasas/metabolismo , Filogenia , Polisacárido Liasas/química , Polisacárido Liasas/genética , Polisacárido Liasas/metabolismo , Análisis de Secuencia de ADN , Secuenciación Completa del Genoma
8.
Proc Natl Acad Sci U S A ; 110(30): 12180-5, 2013 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-23824293

RESUMEN

Recent observations of flagellar counterbend in sea urchin sperm show that the mechanical induction of curvature in one part of a passive flagellum induces a compensatory countercurvature elsewhere. This apparent paradoxical effect cannot be explained using the standard elastic rod theory of Euler and Bernoulli, or even the more general Cosserat theory of rods. Here, we develop a geometrically exact mechanical model to describe the statics of microtubule bundles that is capable of predicting the curvature reversal events observed in eukaryotic flagella. This is achieved by allowing the interaction of deformations in different material directions, by accounting not only for structural bending, but also for the elastic forces originating from the internal cross-linking mechanics. Large-amplitude static configurations can be described analytically, and an excellent match between the model and the observed counterbend deformation was found. This allowed a simultaneous estimation of multiple sperm flagellum material parameters, namely the cross-linking sliding resistance, the bending stiffness, and the sperm head junction compliance ratio. We further show that small variations on the empirical conditions may induce discrepancies for the evaluation of the flagellar material quantities, so that caution is required when interpreting experiments. Finally, our analysis demonstrates that the counterbend emerges as a fundamental property of sliding resistance in cross-linked filamentous polymer bundles, which also suggests that cross-linking proteins may contribute to the regulation of the flagellar waveform in swimming sperm via counterbend mechanics.


Asunto(s)
Axonema , Modelos Teóricos
9.
J Obstet Gynaecol Res ; 41(2): 314-8, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25227922

RESUMEN

Arteriovenous fistula is any abnormal connection between an artery and a vein that bypasses the normal capillary bed and shunts arterial blood directly to the venous circulation. Uterine arteriovenous fistula (UAVF) is a potentially life-threatening condition by causing massive bleeding. This report describes a case of UAVF with massive hemorrhage. Prior to surgery, endovascular catheters for balloon occlusion were placed within bilateral uterine arteries. During surgery, the surgeon requested temporary balloon inflation for navigating and identifying inflow arteries. The balloon was kept inflated during the ligation of the vessels. Once ligation was completed, the balloon was deflated to confirm hemostasis. A total hysterectomy with removal of the UAVF was successfully achieved without significant blood loss. The fistula, in the resected specimen, was confirmed histologically with Elastica van Gieson staining. The preoperative placement of endovascular balloon-occlusion catheters should be considered when hysterectomy is planned where UAVF is located at the cardinal ligament.


Asunto(s)
Fístula Arteriovenosa/cirugía , Pérdida de Sangre Quirúrgica/prevención & control , Histerectomía/efectos adversos , Arteria Uterina/cirugía , Taponamiento Uterino con Balón , Hemorragia Uterina/prevención & control , Fístula Arteriovenosa/complicaciones , Femenino , Humanos , Histerectomía/métodos , Persona de Mediana Edad , Hemorragia Uterina/etiología
10.
Arterioscler Thromb Vasc Biol ; 33(9): 2137-46, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23868935

RESUMEN

OBJECTIVE: Low-density lipoprotein receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that is abundant in vascular smooth muscle cells. Mice in which the lrp1 gene is deleted in smooth muscle cells (smLRP1(-/-)) on a low-density lipoprotein receptor-deficient background display excessive platelet derived growth factor-signaling, smooth muscle cell proliferation, aneurysm formation, and increased susceptibility to atherosclerosis. The objectives of the current study were to examine the potential of LRP1 to modulate vascular physiology under nonatherogenic conditions. APPROACH AND RESULTS: We found smLRP1(-/-) mice to have extensive in vivo aortic dilatation accompanied by disorganized and degraded elastic lamina along with medial thickening of the arterial vessels resulting from excess matrix deposition. Surprisingly, this was not attributable to excessive platelet derived growth factor-signaling. Rather, quantitative differential proteomic analysis revealed that smLRP1(-/-) vessels contain a 4-fold increase in protein levels of high-temperature requirement factor A1 (HtrA1), which is a secreted serine protease that is known to degrade matrix components and to impair elastogenesis, resulting in fragmentation of elastic fibers. Importantly, our study discovered that HtrA1 is a novel LRP1 ligand. Proteomics analysis also identified excessive accumulation of connective tissue growth factor, an LRP1 ligand and a key mediator of fibrosis. CONCLUSIONS: Our findings suggest a critical role for LRP1 in maintaining the integrity of vessels by regulating protease activity as well as matrix deposition by modulating HtrA1 and connective tissue growth factor protein levels. This study highlights 2 new molecules, connective tissue growth factor and HtrA1, which contribute to detrimental changes in the vasculature and, therefore, represent new target molecules for potential therapeutic intervention to maintain vessel wall homeostasis.


Asunto(s)
Aorta/enzimología , Aortitis/enzimología , Factor de Crecimiento del Tejido Conjuntivo/metabolismo , Miocitos del Músculo Liso/enzimología , Receptores de LDL/metabolismo , Serina Endopeptidasas/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Factores de Edad , Envejecimiento , Animales , Aorta/fisiopatología , Aorta/ultraestructura , Aortitis/genética , Aortitis/patología , Aortitis/fisiopatología , Presión Sanguínea , Células Cultivadas , Dilatación Patológica , Tejido Elástico/metabolismo , Endocitosis , Activación Enzimática , Matriz Extracelular/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Fibrosis , Serina Peptidasa A1 que Requiere Temperaturas Altas , Ligandos , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad , Masculino , Ratones , Ratones Noqueados , Proteómica/métodos , Receptores de LDL/deficiencia , Receptores de LDL/genética , Proteínas Supresoras de Tumor/deficiencia , Proteínas Supresoras de Tumor/genética
11.
Materials (Basel) ; 17(2)2024 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-38276442

RESUMEN

The issue of large deflections of textiles occurs primarily when analyzing the "drape" of curtains, tablecloths and other flat textile products. The correct drape is particularly important from an aesthetic point of view. Additionally, there is a problem with the stability of the folds created during the drape process. The analysis of this problem is difficult due to the occurrence of large deflections and non-linear properties of the material. In this article, a selected fragment of the above-mentioned issue was tested, relating only to the stability of the fold formed under given loading conditions. A typical example is a fabric resting on a flat surface and loaded with compressive forces. The presented considerations lead to obtaining the deflection curve for a given self-weight and compressive force. Additionally, the obtained shape was tested for stability. Two shape parameters used in the analysis can be applied for the simulation of different shapes of the deflection curve. The analysis has been made using the energy method relating to the total potential energy of the object. The obtained results may be used in algorithms and simulation programs for fabric folding, buckling and for another applications in the area of textile mechanics.

12.
Pathol Int ; 63(12): 615-8, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24422959

RESUMEN

Solitary pulmonary capillary hemangioma (SPCH) is a rare benign lung tumor that must be distinguished from small and early lung cancers. Here, we report a case of SPCH for which we performed frozen section diagnosis. The patient was a 55-year-old Japanese woman. Five years before the operation, mixed ground-glass opacity was detected by computed tomography in the left posterior basal segment of the lower lobe (S10). Because the interior tumor density of the ground-glass opacity increased slightly, video-assisted thoracic surgery wedge resection was performed. Frozen section diagnosis revealed a benign tumor without proliferation of atypical epithelial cells. The tumor had narrow alveolar lumens, thickened alveolar septa and a clear boundary separating it from normal lung tissue. The proliferated lumens varied in size and were lined with single layers of flat cells. After the operation, immunohistochemical staining of a paraffin section revealed that the thickened alveolar septa resulted from the proliferation of capillary vessels, the flat cells of which were positive for CD31 and CD34 and negative for podoplanin; the tumor was diagnosed as SPCH. Here, we discuss the pathological features of SPCH on frozen sections with reference to this case and review previous related reports.


Asunto(s)
Hemangioma Capilar/patología , Neoplasias Pulmonares/patología , Pulmón/patología , Femenino , Secciones por Congelación , Humanos , Persona de Mediana Edad
13.
Data Brief ; 48: 109261, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37383742

RESUMEN

A significant problem in diffusion MRI (dMRI) is the lack of understanding regarding which microstructural features account for the variability in the diffusion tensor imaging (DTI) parameters observed in meningioma tumors. A common assumption is that mean diffusivity (MD) and fractional anisotropy (FA) from DTI are inversely proportional to cell density and proportional to tissue anisotropy, respectively. Although these associations have been established across a wide range of tumors, they have been challenged for interpreting within-tumor variations where several additional microstructural features have been suggested as contributing to MD and FA. To facilitate the investigation of the biological underpinnings of DTI parameters, we performed ex-vivo DTI at 200 µm isotropic resolution on sixteen excised meningioma tumor samples. The samples exhibit a variety of microstructural features because the dataset includes meningiomas of six different meningioma types and two different grades. Diffusion-weighted signal (DWI) maps, DWI maps averaged over all directions for given b-value, signal intensities without diffusion encoding (S0) as well as DTI parameters: MD, FA, in-plane FA (FAIP), axial diffusivity (AD) and radial diffusivity (RD), were coregistered to Hematoxylin & Eosin- (H&E) and Elastica van Gieson-stained (EVG) histological sections by a non-linear landmark-based approach. Here, we provide DWI signal and DTI maps coregistered to histology sections and describe the pipeline for processing the raw DTI data and the coregistration. The raw, processed, and coregistered data are hosted by Analytic Imaging Diagnostics Arena (AIDA) data hub registry, and software tools for processing are provided via GitHub. We hope that data can be used in research and education concerning the link between the meningioma microstructure and parameters obtained by DTI.

14.
JACC Basic Transl Sci ; 7(9): 934-947, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36317128

RESUMEN

Emerging evidence supports that intestinal microbial metabolite short-chain fatty acids (SCFAs) increase the pool of regulatory T cells (Tregs) in the colonic lamina propria (cLP) and protect against nonintestinal inflammatory diseases, such as atherosclerosis and post-infarction myocardial inflammation. However, whether and how SCFAs protect the inflamed aortas of subjects with abdominal aortic aneurysm (AAA) remains unclear. Here, the authors revealed the protective effect of SCFAs on AAA in mice and the expansion of Tregs in the cLP, and propionate exerted Treg-dependent protection against AAA by promoting the recirculation of cLP-Tregs through colonic draining lymph nodes (dLNs) to the inflamed aorta.

15.
AAS Open Res ; 4: 46, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34632271

RESUMEN

BACKGROUND: The recovery of phenolic compounds is seen as an arduous task because phenolic compounds are available as free aglycones, as sugar or ester conjugates, or as polymers with several monomeric components. This study looks at the optimization of factors that affect the efficiency for the extraction of phenolic compounds from the stem-bark of Funtumia elastica. METHODS: Five independent variables (solvent concentration, time, the temperature, solid-liquid ratio, and pH) of the extraction process were selected. Single factor analysis as well as the response surface method was used to evaluate the impact of the selected factors on the total phenolic content. The effect of the extraction factors on the phenolic content was tested for its statistical significant (p <0.05). For the response surface method, a five/factor, five/level central composite design was used, and a fitted second-order polynomial regression model equation was used to show how the extraction parameters affected the total phenolic recovery. RESULTS: The predicted value (R² of 0.5917) agreed with the adjusted value (R² of 0.7707). The residuals for response predictions were less than 5%. The optimal factors for the extraction were ethanol concentration of 75.99% v/v, extraction time of 193.86 minutes, temperature of 63.66°C, pH of 5.62, and solid-liquid ratio of 1:21.12 g/mL. Actual overall content of the phenolic compounds was validated at 82.83 ± 3.335 mg gallic acid equivalent (GAE) /g weight of extract, which agreed with the predicted response of 89.467 mg GAE/g of the dried extract under the optimal factors. CONCLUSIONS: The rich phenolic content of stem-bark of Funtumia elastica points to its potential as a functional medicinal product to alleviate diseases caused by oxidative stress such as asthma, breathing disorders, inflammation, and cardiovascular diseases. The results obtained indicate that, the studied optimal conditions support effective phenolics extraction of Funtumia elastica.

16.
Micromachines (Basel) ; 12(6)2021 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-34208685

RESUMEN

Copepod nauplii are larval crustaceans with important ecological functions. Due to their small size, they experience an environment of low Reynolds number within their aquatic habitat. Here we provide a mathematical model of a swimming copepod nauplius with two legs moving in a plane. This model allows for both rotation and two-dimensional displacement by the periodic deformation of the swimmer's body. The system is studied from the framework of optimal control theory, with a simple cost function designed to approximate the mechanical energy expended by the copepod. We find that this model is sufficiently realistic to recreate behavior similar to those of observed copepod nauplii, yet much of the mathematical analysis is tractable. In particular, we show that the system is controllable, but there exist singular configurations where the degree of non-holonomy is non-generic. We also partially characterize the abnormal extremals and provide explicit examples of families of abnormal curves. Finally, we numerically simulate normal extremals and observe some interesting and surprising phenomena.

17.
Plant Sci ; 310: 110978, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34315594

RESUMEN

The cuticle forms an effective barrier protecting plants from water loss. Its permeability to water and other compounds significantly differs between species, types of cuticle (stomatous, astomatous), and can be affected by a wide variety of ambient conditions. Enzymatic isolation of the leaf cuticle allows obtaining intact cuticles for permeability measurements. However, the most available gravimetric method, which is used for the assessment of water permeability of isolated cuticles, requires a relatively large area of the cuticle and does not allow the determination of membrane heterogeneity. We propose a new method for the determination of water permeance based on an on-line detection of water flux from a liquid phase to the atmosphere through isolated leaf cuticles in semi-flow chambers. This approach is new in using the phenomenon of surface plasmon resonance for the detection of the liquid phase refractive index affected by water vapor. Isolated cuticles of the leaves of Ficus elastica and an artificial polyethersulfone membrane were used for method evaluation. The composition of cuticular wax and its influence on cuticular permeability was also studied. It has been confirmed that the application of the surface plasmon resonance principle can be used for the assessment of leaf cuticle water permeability and heterogeneity.


Asunto(s)
Ficus/química , Ficus/metabolismo , Resonancia por Plasmón de Superficie/métodos , Ceras/química , Ceras/metabolismo
18.
Fitoterapia ; 151: 104869, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33657429

RESUMEN

The phytochemical study of leaves of Funtumia elastica led to the isolation of three undescribed ursane derivatives, funtumic acids A, B and C (1-3), as well as one steroidal alkaloid, elasticine (4) and five other known compounds (5-9). Their structures were elucidated on the basis of NMR, MS, IR, UV spectroscopic data as well as by comparison with the literature. The compound 5-hydroxypyridine-3-carboxamide (9) was isolated for the first time from the Apocynaceae family. All the isolated compounds were evaluated for their antiparasitic effects against 3D7 and Dd2 strains of Plasmodium falciparum and promastigotes of Leishmania donovani (MHOM/SD/62/1S). Compounds 1-4 possessed good in vitro antimalarial activities against CQR Dd2 with IC50 values ranging from 4.68 to 5.36 µg/mL and moderate on CQS 3D7. Only compounds 1 and 2 showed leishmanicidal activities with IC50 values ranging between 10.49 and 13.21 µg/mL. In addition, crude extract exhibited potent antiplasmodial (IC50 0.91 and 3.12 µg/mL) and antileishmanial (IC50 3.32 µg/mL) activities, thus demonstrating their potential synergistic action.


Asunto(s)
Alcaloides/farmacología , Antimaláricos/farmacología , Antiprotozoarios/farmacología , Apocynaceae/química , Triterpenos/farmacología , Alcaloides/aislamiento & purificación , Animales , Antimaláricos/aislamiento & purificación , Antiprotozoarios/aislamiento & purificación , Camerún , Leishmania donovani/efectos de los fármacos , Ratones , Estructura Molecular , Fitoquímicos/aislamiento & purificación , Fitoquímicos/farmacología , Hojas de la Planta/química , Plasmodium falciparum/efectos de los fármacos , Células RAW 264.7 , Triterpenos/aislamiento & purificación
19.
Int J Rob Res ; 29(10): 1263-1280, 2010 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-25125773

RESUMEN

Robots consisting of several concentric, preshaped, elastic tubes can work dexterously in narrow, constrained, and/or winding spaces, as are commonly found in minimally invasive surgery. Previous models of these "active cannulas" assume piecewise constant precurvature of component tubes and neglect torsion in curved sections of the device. In this paper we develop a new coordinate-free energy formulation that accounts for general preshaping of an arbitrary number of component tubes, and which explicitly includes both bending and torsion throughout the device. We show that previously reported models are special cases of our formulation, and then explore in detail the implications of torsional flexibility for the special case of two tubes. Experiments demonstrate that this framework is more descriptive of physical prototype behavior than previous models; it reduces model prediction error by 82% over the calibrated bending-only model, and 17% over the calibrated transmissional torsion model in a set of experiments.

20.
Materials (Basel) ; 13(7)2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32244574

RESUMEN

A theoretical model concerning the finite bending of a prismatic hyperelastic solid has been recently proposed. Such a model provides the 3D kinematics and the stress field, taking into account the anticlastic effects arising in the transverse cross sections also. That model has been used later to extend the Elastica in the framework of finite elasticity. In the present work, Finite Element (FE) analyses of some basic structural systems subjected to finite bending have been carried out and the results have been compared with those provided by the theoretical model performed previously. In the theoretical formulation, the governing equation is the nonlinear local relationship between the bending moment and the curvature of the longitudinal axis of the bent beam. Such a relation has been provided in dimensionless form as a function of the Mooney-Rivlin constitutive constants and two kinematic dimensionless parameters termed Eulerian slenderness and compactness index of the cross section. Such parameters take relevance as they are involved in the well-known Searle parameter for bent solids. Two significant study cases have been investigated in detail. The results point out that the theoretical model leads to reliable results provided that the Eulerian slenderness and the compactness index of the cross sections do not exceed fixed threshold values.

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