Quantitative Thermal Microscopy Measurement with Thermal Probe Driven by dc+ac Current

Quantitative thermal measurements with spatial resolution allowing the examination of objects of submicron dimensions are still a challenging task. The quantity of methods providing spatial resolution better than 100 nm is very limited. One of them is scanning thermal microscopy (SThM). This method is a variant of atomic force microscopy which uses a probe equipped with a temperature sensor near the apex. Depending on the sensor current, either the temperature or the thermal conductivity distribution at the sample surface can be measured. However, like all microscopy methods, the SThM gives only qualitative information. Quantitative measuring methods using SThM equipment are still under development. In this paper, a method based on simultaneous registration of the static and the dynamic electrical resistances of the probe driven by the sum of dc and ac currents, and examples of its applications are described. Special attention is paid to the investigation of thin films deposited on thick substrates. The influence of substrate thermal properties on the measured signal and its dependence on thin film thermal conductivity and film thickness are analyzed. It is shown that in the case where layer thicknesses are comparable or smaller than the probe–sample contact diameter, a correction procedure is required to obtain actual thermal conductivity of the layer. Experimental results obtained for thin SiO\(_{\mathrm {2}}\) and BaTiO\(_{\mathrm {3 }}\)layers with thicknesses in the range from 11 nm to 100 nm are correctly confirmed with this approach.     

Direct programming of a central pattern generator for periodic motions by touching

Much of the literature shows that Central Pattern Generators (CPGs) are a good approach for generating periodic motions for legged robots. In most of the presented works the numerous CPG parameters are set by automatic techniques like genetic algorithms. This gives the user little control over the resulting motions, since all of the desired features of the motion must be encoded by a fitness/score function. In this paper we present the idea of setting the CPG parameters by interaction with the user, in particular by using the tactile interaction. Key elements of the system are a CPG network, a touch protocol and a self-collision prevention system. In this paper we present a practical implementation of each element that confirms the feasibility of the method.     

The Potential of Al2O3–ZrO2-Based Composites,Formed via CSC Method,in Linear Infrastructure Applications Based on Their Mechanical,Thermal and Environmental performance

Metallurgical and Materials Transactions A - Ceramic-ceramic composites have been prepared using the centrifugal slip casting method (CSC). The method has so far been mainly utilized in making...     

Molecular-beam epitaxy growth and characterization of mid-infrared quantum cascade laser structures

The development of molecular-beam epitaxy (MBE) of GaAs/AlGaAs heterostructures, used for fabrication of ∼9 μm quantum cascade lasers (QCLs), is reported. The X-ray diffractometry (XRD) structural characterization, as an integral part of this process, is presented as well. Some conclusions, concerning the relationships between the used type of epitaxial technology and the necessity of special procedures of growth rate (V_gr) calibration, are reached. The influence of the structural features of the QCL active region on the electronic band structure is calculated, and consequently some predictions as to the device electrical properties are presented as well.     

Sorption of lanthanide ions on biochar composites

Sorption of lanthanum(Ⅲ), cerium(Ⅲ) and neodymium(Ⅲ) ions from the aqueous solutions of mixtures through adsorption on the biochar composites was investigated as a function of sorbent mass, pH, phase contact time and initial concentration of solutions at 295 K. The maximum removal of lanthanide ions takes place under the following conditions: 0.1 g of sorbent mass, pH 4 and 360 min contact time for all studied initial concentrations of solutions. Kinetics of La(Ⅲ), Ce(Ⅲ) and Nd(Ⅲ) ions sorption proceeded by a fast initial uptake reached equilibrium. This process was modelled by means of the pseudo first order, pseudo second order, intraparticle diffusion and Elovich models. The desorption of three lanthanide ions by nitric, hydrochloric and sulfuric acids at a concentration of 1 mol/L from biochar composites was also studied. In order to investigate the sorption mechanism FTIR, XRD and XPS analyses were performed after sorption of ions from the mixture.     

Apoptosis of skeletal muscle myofibers and interstitial cells in experimental heart failure

Congestive heart failure (CHF) is characterized by a limb skeletal muscle myopathy with shift from the slow aerobic, fatigue resistant fibers, to the fast, anaerobic ones, and muscle bulk loss. Apoptosis (A) has been recently demonstrated to play a role in several cardiovascular diseases. AIM OF THE STUDY: we have investigated the role of A in the skeletal muscle of the hindlimbs in an experimental model of CHF. ANIMALS AND METHODS: CHF was induced in 7 males 80-100 g Sprague-Dawley rats with 30 mg/kg monocrotaline. Five age and diet matched controls were also studied. The time course of A was also studied in additional animals at day 0, 17, 24 and 30 days. RESULTS: At day 27 the electrophoretic analysis of myosin heavy chains (MHCs) demonstrated in the CHF rats the occurrence of a myopathy, with disappearance of slow MHC1 in the Tibialis Anterior (TA), and a significant shift from the slow to the fast isoforms in the soleus and EDL. With in situ DNA nick-end labelling (TUNEL) we found in the TA of CHF animals a significantly higher number of TUNEL positive nuclei (0.43 +/- 0.24 v 0.08 +/- 0.02, P<0.02 and TUNEL positive myonuclei (0.031 +/- 0.012 v 0.0025 +/- 0.005, P<0.02). The time course of A showed a progressive rise in interstitial and myocyte A, accompanied by a drop in fibers cross-sectional area and muscle weight/body weight, that came out to be significant at 30 days. Western blot showed a lower expression of Bcl-2 at 27 days and a further drop at 30 days in the CHF rats. Double staining for TUNEL and antibody against anti-MHC2a and anti MHC2b + 2x showed that A occurs non-selectively in all the myofiber types. BetaANP and Right Ventricle Mass/Volume (RVM/V) correlated significantly with total apoptotic nuclei. CONCLUSIONS: In CHF myofibers A can lead to muscle atrophy. Endothelial cells A may produce an imbalance in myofibres nutrition with relative ischemia that triggers the preferential synthesis of fast anaerobic myosin as an adaptive mechanism or alternatively induce myofibres death.     

Environmental footprint as a criterion in the ZTA composites forming process via centrifugal slip casting

The main goal of this study was to optimize the technological process of forming and sintering Zirconia Toughened Alumina (ZTA) composites in terms of reducing energy demand. Based on the results of Life Cycle Assessment carried out according to ISO 14044 and EN 15805 standards, the elimination of preliminary homogenization of ceramic suspension in the planetary mill, allowed to reduce energy consumption by over 25%. The method of forming ZTA materials by CSC method, allowed to obtain finished tube-shaped products, which did not require any mechanical treatment after sintering. Such an approach may be an alternative solution for production of ZTA pipes that can be used in transport of aggressive substances, even in extreme corrosive or temperatures conditions.     

The Agonist Action of Alkylphenols on TRPA1 Relates to Their Effects on Membrane Lipid Order: Implications for TRPA1-Mediated Chemosensation

The Transient Receptor Potential Ankyrin 1 cation channel (TRPA1) is a broadly-tuned chemosensor expressed in nociceptive neurons. Multiple TRPA1 agonists are chemically unrelated non-electrophilic compounds, for which the mechanisms of channel activation remain unknown. Here, we assess the hypothesis that such chemicals activate TRPA1 by inducing mechanical perturbations in the plasma membrane. We characterized the activation of mouse TRPA1 by non-electrophilic alkylphenols (APs) of different carbon chain lengths in the para position of the aromatic ring. Having discarded oxidative stress and the action of electrophilic mediators as activation mechanisms, we determined whether APs induce mechanical perturbations in the plasma membrane using dyes whose fluorescence properties change upon alteration of the lipid environment. APs activated TRPA1, with potency increasing with their lipophilicity. APs increased the generalized polarization of Laurdan fluorescence and the anisotropy of the fluorescence of 1,6-diphenyl-1,3,5-hexatriene (DPH), also according to their lipophilicity. Thus, the potency of APs for TRPA1 activation is an increasing function of their ability to induce lipid order and membrane rigidity. These results support the hypothesis that TRPA1 senses non-electrophilic compounds by detecting the mechanical alterations they produce in the plasma membrane. This may explain how structurally unrelated non-reactive compounds induce TRPA1 activation and support the role of TRPA1 as an unspecific sensor of potentially noxious compounds.     

Composites of Nucleic Acids and Boron Clusters (C2B10H12) as Functional Nanoparticles for Downregulation of EGFR Oncogene in Cancer Cells

Epidermal growth factor receptor (EGFR) is one of the most promising molecular targets for anticancer therapy. We used boron clusters as a platform for generation of new materials. For this, functional DNA constructs conjugated with boron clusters (B-ASOs) were developed. These B-ASOs, built from 1,2-dicarba-closo-dodecaborane linked with two anti-EGFR antisense oligonucleotides (ASOs), form with their complementary congeners torus-like nanostructures, as previously shown by atomic force microscope (AFM) and transmission electron cryo-microscopy (cryo-TEM) imaging. In the present work, deepened studies were carried out on B-ASO’s properties. In solution, B-ASOs formed four dominant complexes as confirmed by non-denaturing polyacrylamide gel electrophoresis (PAGE). These complexes exhibited increased stability in cell lysate comparing to the non-modified ASO. Fluorescently labeled B-ASOs localized mostly in the cytoplasm and decreased EGFR expression by activating RNase H. Moreover, the B-ASO complexes altered the cancer cell phenotype, decreased cell migration rate, and arrested the cells in the S phase of cell cycle. The 1,2-dicarba-closo-dodecaborane-containing nanostructures did not activate NLRP3 inflammasome in human macrophages. In addition, as shown by inductively coupled plasma mass spectrometry (ICP MS), these nanostructures effectively penetrated the human squamous carcinoma cells (A431), showing their potential applicability as anticancer agents.