Thin Ones Research Articles

Network analysis of the left anterior descending coronary arteries in swim-trained rats by an in situ video microscopic technique

BackgroundWe aimed to identify sex differences in the network properties and to recognize the geometric alteration effects of long-term swim training in a rat model of exercise-induced left ventricular (LV) hypertrophy.MethodsThirty-eight Wistar rats were divided into four groups: male sedentary, female sedentary, male exercised and female exercised. After training sessions, LV morphology and function were checked by echocardiography. The geometry of the left coronary artery system was analysed on pressure-perfused, microsurgically prepared resistance artery networks using in situ video microscopy. All segments over > 80 μm in diameter were studied using divided 50-μm-long cylindrical ring units of the networks. Oxidative-nitrative (O-N) stress markers, adenosine A2A and estrogen receptor (ER) were investigated by immunohistochemistry.ResultsThe LV mass index, ejection fraction and fractional shortening significantly increased in exercised animals. We found substantial sex differences in the coronary network in the control groups and in the swim-trained animals. Ring frequency spectra were significantly different between male and female animals in both the sedentary and trained groups. The thickness of the wall was higher in males as a result of training. There were elevations in the populations of 200- and 400-μm vessel units in males; the thinner ones developed farther and the thicker ones closer to the orifice. In females, a new population of 200- to 250-μm vessels appeared unusually close to the orifice.ConclusionsPhysical activity and LV hypertrophy were accompanied by a remodelling of coronary resistance artery network geometry that was different in both sexes.

Anomalous diameter dependent electrical transport in individual CuO nanowire

Cupric oxide (CuO) nanostructure arrays have been extensively investigated for solar energy harvesting, electrochemical energy storage, chemical sensing, field-effect transistors, etc. Although most of these applications depend on the collective behavior of an array of such structures, analysis of electrical transport in a single nanostructure, which are the building blocks, is essential for understanding both the fundamental aspects and device performance. Here we report the electrical conduction mechanism in thermally grown single CuO nanowire (NW), which reveals that the current density has an anomalous dependence on the diameter of the NWs—decreasing with an increase in diameter. An analysis of the electrical behavior at room temperature shows that the current density in CuO NWs has different slopes in different regions of the applied bias indicating distinct types of charge transport, which are characterized as near Ohmic (lower voltage), trap controlled, and space charge limited conduction (higher applied voltage). Further, the trap density and activation energy are calculated from the temperature-dependent current density data, which shows higher values (9.38 × 1015cm−3, 79.4 meV) in thicker NWs compared to that in the thinner ones (3.96 × 1015 cm−3, 63.9 meV). Investigation of the NWs with Raman and photoluminescence spectra establishes the presence of Cu2O phase in thicker NWs, which act as hole traps to hinder the charge transport in p-type CuO and resulting in lower conductivity at higher diameters. This study helps to design and fabricate prototype nanodevices with desired conductivity based on CuO NWs.

Effect of FRP thickness on axial compressive behavior of Glass Fiber Reinforced Polymer–confined lightweight concrete cylinders

It is well known that FRP can improve the performance of concrete. However, the effectiveness of FRP to enhance the performance of lightweight concrete is less explored. This study aims to investigate the effect of FRP thickness on the axial compressive behavior of GFRP-confined lightweight concrete cylinders. Nine lightweight concrete specimens wrapped with 0, 1, 2, and 3 sheets of GFRP were manufactured and tested until failure. The test confirms that the thicker specimens experienced higher axial stress and strain compared to the thinner ones.

Oscillations of Slabs Supported on Point Supports

The urgent task which is addressed in this work is the development of methods for determining the frequencies and forms of vibrations, as well as dynamic reactions of thin slabs with various support systems, including those supported on point supports.The aim of the work is to develop experimental methods for determining the frequencies and forms of natural oscillations of slabs with holes and thin point-supported square solid ones.In this work, the frequencies of square slabs with free edges resting on point supports are determined; the dependences of the vibration frequencies of slabs from the coordinates of point supports and the dimensions of symmetrically placed holes; the arrangement of point supports, wherein the basic frequency of free vibrations of the slab is maximum; the frequencies, shapes, and decrements of vibrations of square slabs supported on four point supports were determined experimentally, as well as the influence of the presence of holes and the degree of pinching of the supports on the dynamic characteristics of these slabs.The article deals with the method and analysis of results of experimental investigations of dynamic characteristics of square solid slabs with holes.Comparison of experimental and theoretical values of frequencies of natural oscillations of slabs showed their good similarity.The results of this work can be applied to dynamic and seismic calculations of point-supported square slabs.

Evaluating the Effect of Asymmetric Cross-section in Free Vibration and Bending Analysis Results of FG Sandwich Beam by Proposing Simple Efficient Element

In this paper, the asymmetric effect of the cross-section on the free vibration and bending analysis of FG sandwich beams are evaluated. For this purpose, a simple, efficient element is formulated. The new element is created based on the Timoshenko beam theory. The third- and second-order polynomials will be used for vertical displacement and rotation fields, respectively. The proposed formulation will be written based on satisfying the equilibrium equation. Satisfying the equilibrium equation of the Timoshenko beam, in addition to increasing element efficiency, will reduce the number of nodal unknowns. Several benchmark tests with different boundary conditions are used for thin and thick beams to prove the efficiency of the proposed element. The responses of the good elements of other researchers have been used for comparison. Numerical tests prove the rapid convergence rate and high accuracy of the proposed element in free vibration and bending analysis of the beams with various cross-section types and different boundary conditions. The pinned-sliding support conditions for the beam are used to evaluate the asymmetric effect of the cross-section. The use of asymmetric cross-sections creates additional axial displacements and intensifies the deflection of the beam under the lateral load. By increasing the asymmetry, the additional axial displacement and vertical displacement increase. These additional deflections for thin beams are more than thick ones. Also, asymmetry results in increasing the natural frequencies of beams. In the free vibration analysis, the effect of asymmetry on thick beams is more than thin ones.

Climatology of low-level temperature inversions over China based on high-resolution radiosonde measurements

Low-level temperature inversions play crucial roles in inhibiting vertical exchange of energy and mass, and may lead to air pollutants accumulation. The climatological study of them provides a fundamental overview of the static stability of atmosphere and is indispensable for air pollution controls. Based on high-vertical-resolution radiosondes at 00 and 12 UTC during 2011–2018, this work comprehensively examined the spatial and temporal variability of three characteristics (occurrences, strengths, and depths) of low-level inversions in China. Results revealed that inversions are prevalent (more than 80% of the observation records) over Eastern China. The northern part of Eastern China is dominated by the thick strong surface-based inversions with median thickness and strength of 200 m and 3 K, while the southern part by thin weak elevated ones of 80 m and 0.8 K. Tibetan Plateau experiences rare inversions (less than 50% of the time) which tend to be strong thick surface-based inversions with median depth and intensity of 170 m and 4 K. Inversion depths and strengths are positively correlated. The three properties of inversions present remarkable seasonal variations. Generally, inversions are strongest, thickest, and most frequent in winter and least so in summer, with median intensity and depth ranging from 0.3 K and 80 m to 5 K and 220 m. This paper also analyzed the monthly variations of inversions of four representative stations (Harbin, Urumqi, Beijing, and Chongqing) in details. These four cities are known for frequent severe air pollution events. The quantitative investigations of inversions may play a significant role in atmospheric environmental management.

Adaptive momentum-based optimization to train deep neural network for computer simulation of hygro-thermo-mechanical vibration performance of laminated plates

This article explores the vibration response of the hybrid composite structure with the aid of the adaptively tuned deep neural network (DNN). In order to find the features of the design-points, the semi-numerical technique is applied to the governing differential equations of the system acquired on the foundation of the kinematic theory with refined higher order terms. Considering higher order terms made the accuracy of this analysis suitable for moderately thick plates as well as thin ones. DNN is trained for vibrational characteristics of the design-points by employing adaptive learning rate method as the high-speed optimizer. Accuracy of the semi-numerical method (used for determining the design-points) is evaluated through the comparison with the results reported in the published studies. While, the validity of the DNN-based model in predicting the response of the system at design-points is tested and confirmed by analyzing the trend of mean squared error.

Growth, leaf gas exchange and physiological parameters of two Glycyrrhiza glabra L. populations subjected to salt stress condition

Salinity is the major environmental stress affecting growth and physiological processes in plants. Glycyrrhiza glabra (licorice) is a perennial medicinal plant having many secondary metabolites. The effects of 0, 100, 200, 400, 600, and 800 mM NaCl on growth parameters, leaf relative water content, chlorophyll index, gas exchange parameters, membrane stability index, antioxidant activity, phenolic compounds, flavonoid, and soluble carbohydrate contents of licorice populations (Fars and Khorasan) cultivated with different rhizomes diameters were evaluated. The soil and rhizomes elements were also studied. The results indicated that the salinity significantly decreased the growth parameters, relative water content, and membrane stability index, compared to the controls. The thicker rhizomes can grow more than thinner ones in saline soil. Chlorophyll index and leaf gas exchange were declined under salt stress. Besides, the soluble carbohydrate content was decreased. Salinity caused oxidative stress in licorice rhizomes, so that by decreasing the membrane stability index, antioxidant capacity, phenolic compounds, and flavonoid contents of rhizomes have increased in line with NaCl treatments. Na+, Cl−, and Ca2+ levels increased, but K+ concentration was reduced. The PCA-biplot analysis revealed that Fars and Khorasan populations had different responses to salinity. The length of rhizomes, flavonoids, phenolic compounds, and soluble carbohydrates of two licorice populations and salinity stress had the largest amount of difference of traits. Thus, the elevation of osmolytes, the nutrient balance, and the antioxidant capacity lead to protect of licorice under osmotic, ionic, and oxidative stress, which is caused by the salinity stress. Accordingly, G. glabra can withstand salinity up to 600 mM NaCl and be introduced as a halophyte plant.

Effect of Crystalline Microstructure Evolution on Thermoelectric Performance of PEDOT : PSS Films

Although organic polymer thermoelectric (TE) materials have witnessed explosive advances in the recent decade, the molecular mechanism of crystallization engineering of TE performance, even for the most successful polymer of poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS), is still far from clear. Here, we deepen the understanding of the role of annealing-induced crystalline microstructure evolution on TE performance of the PEDOT : PSS film with thickness of 10 μ m, which is usually more effective than thin ones in applications. Annealed at optimized temperature of 220°C, the film displays a power factor of 162.5 times of that of the pristine film before annealing. The enhanced TE performance is associated with the changes of crystallographic and morphologic microstructures, including increased crystallinity and crystal grain size, a domain morphology transformation from granular to crystalline nanofibril, and reduced insulating PSS in the skin layer. These variances facilitate the carrier transport by a transition from 3D to 1D hopping, reduce the activation energy, and improve the carrier mobility. The mechanism of crystallization engineering reported here can be conceptually extended to other TE polymers and guides the future rational design of preparation principles for organic and composite TE materials.

Laser dissimilar welding of copper and steel thin sheets for battery production

Laser processing of metallic thin sheets has gained undoubted industrial interest in the last decade especially due to its implications in the e-mobility field. In particular, dissimilar welding of thin sheets made of different materials, such as aluminum, copper, and steel is nowadays recognized as an effective solution for many joining applications in battery and related component production. According to these considerations, the present paper is aimed at evaluating the possibility to perform a sound joining of thin copper sheets on thin steel ones in a lap-welding configuration. This application is of particular interest especially when cylindrical cells have to be electrically connected to any of the elements constituting the battery, such as printed circuit boards, busbars, etc. By means of a continuous wave fiber laser and a galvo scanner, an experimental campaign was carried out in order to define a process window for characterizing the above-mentioned welding application. The results were characterized by means of metallographic analyses, microhardness measurements, electrical conductivity tests, and scanning electron microscopy-energy dispersive system analyses. Particular attention was placed on the role of process parameters in controlling the penetration depth on the lower steel layer, since it constitutes the external housing of the single cell and a drop through can seriously damage the cell itself.

Particle and rain erosion mechanisms on Ti/TiN multilayer PVD coatings for carbon fibre reinforced polymer substrates protection

PVD coatings have been studied as candidates for erosion protection of carbon fibre reinforced polymers. Thus, multilayer Ti/TiN coating stacks with different thicknesses ranging from 1.5 to 11 μm have been deposited by pulsed DC magnetron sputtering on carbon fibre reinforced polymers. The coatings were tested under particle erosion and rain erosion conditions showing opposite trends with thickness. The results show how different mechanisms dominate depending on the conditions used and revealing how thickness, surface finishing of the CFRP substrates and adhesion affect the performance of the coatings under different erosive conditions. In the case of sand erosion, thin coatings fail due to delamination in the vicinity of carbon fibres due to substrate deformation under impacts, while thick coatings are able to avoid substrate driven erosion, even if the adhesion is lower, and smooth erosive behaviour is obtained until the failure appears at specific spots. On the contrary, thin coatings show better behaviour under rain erosion conditions, as high speed impacts induces larger substrate deformation, even on the thicker coatings, that delaminates faster than thinner ones due to their poorer adhesion.

On the failure of punching process

Punching is recognized to be useful in sheet cold forming. To the best of our knowledge, researchers have been interested just in thin ones. That is why the interest of this paper is in premature AISI D2 punch damage in case of thick S500 MC plettac. Several techniques such as optical microscopy, Energy dispersive spectroscopy (EDS), Vickers hardness and scanning electron microscopy (SEM) were used in order to extract failure causes. The obtained results showed that back-up plate, corrosion, wear and fatigue as well as head punch cracking, scaling, mating and inflation lead to a short-life service. Microstructures characterizations exhibit fractured chromium carbides and lamellar pearlite bending during head tool and back-up plate contact.

About the end of the nerves in pepsin glands in mammals

Nerves spreading into the mucous membrane of mammals emerge from Meissner's plexus and form, in turn, two plexuses: one - under the bottom of the peptic glands, the other - between the named glands and up the epithelium of the gastric mucosa. The nerve fibers of the interglandular plexus consist of non-fleshy, non-varicose nerve fibers with a slight admixture of thin fleshy ones.

Method for Accountting the Effect of End Washers on the Flow Around the Wing with Spanwise Profiles

Purpose of research is to develop a method for accounting for the influence of end washers on the flow of wings with an arbitrary distribution of fillets over the span.Methods. The installation of end washers significantly improves the aerodynamics of the wing, increasing lift and reducing inductive resistance. The theory of a continuous vortex surface is applied to simulate the effect of end washers on the flow of a volumetric wing. In accordance with it, oblique horseshoe-shaped vortices that model the upper and lower sides of the wing are continuously distributed along the longitudinal panels, into which the half-span of the wing is divided. The bearing parts of each horseshoe-shaped vortex lie in planes parallel to the plane of the wing chords and pass through the points and the middle section of the panel at which the induced velocities are calculated. The free vortices of the wing descend from its ends from the upper and lower surfaces at an angle to the plane of the chords.Results. An algorithm has been developed for calculating the intensity of vortices from the non-permeability condition, taking into account the attached and free vortices of the wing and the end-washer vortices. The vortex densities included in this condition are represented by trigonometric series. The developed method takes into account the geometry of the profile and end washers, the shape of the wing in the plan. The vortices induce an additional velocity at the points on the surface of the wing. To calculate their values, the Biot-savard formula on vortex influence is used.Conclusion. A method for calculating the aerodynamic characteristics of a volumetric wing with end washers has been developed from the unified positions of the theory of a continuous vortex surface. The calculations take into account the geometry of the washers and profile, the shape of the wing in the plan. The method is universal and can be used for wings without washers, including for thin ones.

Facile Tuning and Refractive Index Sensitivity of Localized Surface Plasmon Resonance Inflection Points in Hollow Silver Nanoshells

Hollow metal nanostructures are fascinating because of their unique and surrounding environment-sensitive localized surface plasmon resonances (LSPRs). Herein, we have investigated the hollow silver nanoshell (HSN) sensitivity of different inner core radii and shell thicknesses with respect to change in surrounding medium refractive index. Also, we have shown that the extinction peak of HSNs can be fine-tuned in the visible region as well as biological windows by manipulating the size parameters. Moreover, an enhancement in refractive index sensitivity of 133 to 283 nm/RIU can be achieved in the biological windows by thick hollow silver nanoshells in comparison to thin ones. To achieve a comprehensive study, the sensitivity of homogeneous LSPR extinction inflection points with change in refractive index is also investigated. A consistent improvement in bulk refractive index sensitivity of 36% and 15% is predicted with thick and thin shell layers, respectively. Finally, thick HSNs showed higher refractive index sensitivity when compared with thin ones. Moreover, we envision the idea of more than one molecule detection by tracking the curvature changes. Therefore, we provide a deeper insight into the refractive index sensitivity of homogeneous LSPR inflection points for their use in LSPR-based sensors.

Sulu Olmayan Ortamlarda Katodik olarak elde edilen Kalay Esaslı Filmin Elektrokimyasal Davranışı

Platinum electrode was coated with Sn in order to study electrochemical behavior of Sn based modified electrode in acidic electrolyte. A deep eutectic solvent consisting of ethylene glycol and choline chloride (called Ethaline) was used as deposition electrolyte by applying different voltage and time at two different temperature (room temperature and 55 °C). Tin coated platinum electrode was immersed in Na2SO4 and KOH solutions for the formation of tin oxide and tin hydroxide, respectively. Tin hydroxide and tin oxide films cycled in H2SO4 were not electroactive and these films cannot be used in acidic media for electrochemical devices. Sn electrode electrodeposited at high temperature was more than 500 times thicker than that at room temperature. Thick tin modified electrode electrodeposited in Ethaline at high temperature had the same behavior in neutral and alkaline solution as thin Sn film obtained at room temperature. Thick SnO and Sn(OH)2 films were not electroactive in acidic media the same as thin ones. Sn electrode electrodeposited from deep eutectic solvent at 55 °C and treated with acidic solution was cycled in alkaline electrolyte. Reduction of the resulted film in KOH appeared. This electrode could be used for hydrogen evolution reaction in alkaline media.

The value of lymph node ultrasound and whole body PET/CT in stage IIB/C patients prior to SLNB.

e22079 Background: Stage IIB/IIC (pT3b-T4N0) patients are known to have high-risk primary tumors, even higher risk than some stage IIIA/B melanomas (AJCC Staging System 8th edition), however they follow the same routine to sentinel lymph node biopsy (SLNB) as more low-risk tumors. A priori the risk of finding SLNB or other metastases is much higher for these thick and/or ulcerated primary melanomas compared to the thinner ones. Guidelines are not conclusive regarding the use of preoperative imaging in these cases. Recently, a trend to more frequently use cross-sectional imaging has been noticed. However, others have previously shown that preoperative ultrasound was the most sensitive. The aim of this pilot study was to assess the value of ultrasound (US) and Positron Emission Tomography/Computerized Tomography (PET/CT) prior to SLNB for stage IIB/C (pT3b-T4N0) melanoma patients. Methods: Starting 2019-04, all patients with a pT3b melanoma or higher (8th AJCC) were included. All patients underwent US and PET/CT before their planned lymphoscintigraphy and routine SLNB. Suspected metastases were confirmed with cytologic puncture. Results: A total of 20 patients were screened. Seven patients (35%) had metastases detected by imaging: one by PET/CT, three by US and three by both imaging modalities. Three of these metastases were detected by US as well as PET/CT. All metastases were nodal. For all seven patients treatment was altered to lymph node dissection with adjuvant therapy. Of the 13 patients in whom no metastases were identified by imaging, six (46%) still had a positive sentinel node (SN). Conclusions: This study showed that this select group of patients had a high risk of metastases prior to SLNB and that all recurrences except one, were detected by ultrasound. This suggests that nodal staging with US is sufficient and can replace the need for SLNB when metastases is proven with cytology. Despite negative imaging, SLNB cannot be foregone for pT3b-pT4N0 melanoma patients, as many still have an involved SN. Cross-sectional imaging can be reserved for patients after positive cytology or SN to confirm the absence of distant visceral metastases.

Multi-directional vs. mono-directional multi-step strategies for single point incremental forming of non-axisymmetric components

Multi Stage approach is used in Single Point Incremental Forming (SPIF) to overcome one of the main forming limitations, namely the maximum wall angle, characterizing the single stage process. In this paper, different multi-path strategies for the production of parts with flat edges are considered in order to evaluate the best solution in terms of feasibility and geometrical accuracy of the final part: A) mono-directional incremental draw angle; B) mono-directional incremental draw angle with increasing part side; C) Multi-directional approach with non-horizontal path planes. Strain evaluation by means of CGA (Circular Grid Analysis) and defect analysis have been carried out in order to identify the main limitations of each approach. A defect-free part has been obtained with Strategy C. The developed numerical analysis, showing good agreement with experimental thickness distribution, highlighted the peculiar material redistribution from the thicker zones to the thinner ones occurring using Strategy C.

Two-lines method for estimation of plasma temperature and characterization of plasma parameters in optically thick plasma conditions.

In this paper, the characteristics of laser-induced plasmas are studied by investigation of the spectral line features in laser-induced breakdown spectroscopy (LIBS) experiments. The plasma is produced by focusing of a Nd:YAG laser on standard Al-alloy samples at 30 mJ energy. Here, with the assumption of having a homogenous plasma and by using a semiemperical technical method, the plasma temperature is calculated by the proposal of a new two-lines method. Moreover, by utilizing some theoretical equations, the plasma parameters and the self-absorption magnitude are evaluated according to the radiative transfer equations in local thermodynamic equilibrium (LTE) conditions. The main advantages of this method are that without discrimination between thin plasmas and thick ones, and as well as without straight quantification of the degree of self-absorption, the plasma temperature can be calculated. The results showed that determination of the intensities of the spectral lines, transition parameters, and Stark broadening parameter is adequate for plasma characterization in a typical LIBS experiment.

Growing Coconut Palms in the Pacific Islands: Colliding Knowledge and Values

Abstract Coconuts provided commodities for the West in the form of coconut oil and copra. Once colonial governments established control of the tropical Pacific Islands, they needed revenue so urged European settlers to establish coconut plantations. For some decades most copra came from Indigenous growers. Administrations constantly urged the people to thin old groves and plant new ones like plantations, in grid patterns, regularly spaced and weeded. Local growers were instructed to collect all fallen coconuts for copra from their groves. For half a century, the administrations' requirements met with Indigenous passive resistance. This paper examines the underlying reasons for this, elucidating Indigenous ecological and social values, based on experiential knowledge, knowledge that clashed with Western scientific values.