This article focuses on studying the rheological behavior of isotropic and anisotropic magnetorheological elastomers (MREs), made of carbonyl iron microparticles dispersed into a silicone⁻rubber ...matrix by considering 20 and 30 wt % of microparticles. Sample sets were prepared for each composition, with and without the application of an external magnetic field. Experimental measurements of the material rheology behavior were carried out by a shear oscillatory rheometer at constant temperature, to determine both the shear storage modulus (G') and shear loss modulus (G'') for all characterized samples. Then, experimental data collected from the isotropic and the anisotropic material samples were used to plot the Cole-Cole diagrams to quantify the interfacial adhesion between carbonyl iron microparticles and the silicone-rubber matrix. Furthermore, the Fractional Zener Model (FZM) with two spring-pots in series is used for quantitative analysis of collected experimental data.
This article focuses on evaluating the influence that the addition of carbonyl iron micro-particles (CIPs) and its alignment have on the mechanical and rheological properties for magnetorheological ...elastomers (MREs) fabricated using polydimethylsiloxane (PDMS) elastomer, and 24 wt % of silicone oil (SO). A solenoid device was designed and built to fabricate the corresponding composite magnetorheological material and to perform uniaxial cyclic tests under uniform magnetic flux density. Furthermore, a constitutive material model that considers both elastic and magnetic effects was introduced to predict stress-softening and permanent set effects experienced by the MRE samples during cyclic loading tests. Moreover, experimental characterizations via Fourier transform infrared (FTIR), X-ray diffraction (XRD), tensile mechanical testing, and rheological tests were performed on the produced MRE samples in order to assess mechanical and rheological material properties such as mechanical strength, material stiffness, Mullins and permanent set effects, damping ratio, stiffness magnetorheological effect (SMR), and relative magnetorheological storage and loss moduli effects. Experimental results and theoretical predictions confirmed that for a CIPs concentration of 70 wt %, the material samples exhibit the highest shear modulus, stress-softening effects, and engineering stress values when the samples are subject to a maximum stretch value of 1.64 and a uniform magnetic flux density of 52.2 mT.
Biosensors that incorporate nanomaterials and nanofabrication techniques enable molecular detection of chemical and biological macromolecules with a high degree of specificity and ultrasensitivity. ...Here, we present a novel fabrication process that yields a nanostructure capable of detecting biological macromolecules. The extended core nanocoax (ECC) structure builds on a previously reported nanocoaxial-based sensor. The fabrication of the device incorporates an extended inner pillar, with controllable extension above the annulus and into the surrounding solution. This new design eliminates structural constraints inherent in the original nanocoax architecture. We also provide results demonstrating improvement in biosensing capability. Specifically, we show the capability of the new architecture to detect the B subunit of the Vibrio cholerae toxin at improved sensitivity (100 pg/ml) in comparison to optical enzyme-linked immunosorbant assay (1 ng/ml) and previously reported coaxial nanostructures (2 ng/ml).
•A nanogap coaxial electrode was modified for optimized electrochemical sensing.•100 pg/ml cholera toxin was detected in off-chip electrochemical ELISA.•Limit of detection exceeds that of conventional optical ELISA capability.•Working electrode of architecture was biofunctionalized with thiolated protein G.•Protein G biofunctionalization allowed for on-chip detection of cholera toxin.
Introduction
Cognitive complaints and psychological distress are common in oncologic patients, in particular many studies have focused on women with breast cancer.Patients presenting the phenomenon ...of “chemofog” show changes after chemotherapy with regard to memory and emotional regulaiton.
Objectives
To explore brain connectivity prior to chemotherapy that nevertheless,is understudied.
Methods
We used fMRI to investigate the resting state connectivity in 24 patients before chemotherapy and 15 controls.Patients were assessed with self-administered questionnaires,such as the Patient’s Assessment of Own Functioning Inventory (PAOFI) that quantifies the decrease in perceived functioning in memory, language and problem solving (Image 1).We used a preliminary structural analysis in order to choose which neuropsychological test was affected in correlation with a significant anatomical volume alteration,as showed in the p-value table.Therefore, patients were ranked and divided into two group of “Impaired vs Preserved”, measured using the median of the questionnaire results.Higher scores indicate a poor cognitive self-perceived performance.
Results
Connectivity was altered in amygdala and hippocampus, in the subgroup of patients with higher subjective cognitive complaints i.e with a high PAOFI Memory score.More specifically, we found an association between memory impairment and the increase of the resting state connectivity of both right structures, as opposed to a reduction in left amygdala (Image 3).
Conclusions
These findings may suggest a potential effect on brain functional connectivity of the psychological awareness and stress of cancer itself. We found connectivity alterations for both amygdala and hippocampus, two structures belonging to the limbic system, that is involved in the interplay between cognition and emotions, such as anxiety and fear.
The aim of this article was to investigate the mechanical performance of magnetorheological polyurethane elastomers reinforced with different concentrations of carbonyl iron microparticles (CIPs) in ...which stress softening, energy dissipation, residual strains, microparticles orientation, and magnetic flux density effects will be considered. Other aspects, such as the determination of the dissipated energy during cyclic loading and unloading, were investigated by considering a pseudo-elastic network model that takes into account residual strains, magnetic field intensity, and the isotropic and anisotropic material behavior. Theoretical predictions confirmed that the material shear modulus becomes sensitive not only for higher concentrations of CIPs added into the elastomer material matrix, but also to the magnetic flux intensity that induces attractive forces between CIPs and to the strong bonds between these and the elastomer matrix. It was also found that the addition of CIPs when embedded into the polymer matrix with a predefined orientation enhances the material shear modulus as well as its capacity to dissipate energy when subjected to magnetic flux density in loading and unloading directions.
An all‐solution‐processed transparent conductive electrode with sheet resistance one order of magnitude smaller than conventional nanowire‐based transparent conductors has been developed. This is ...achieved by integrating all‐solution produced microwires with a nanowire solution and electroplating and electrowelding. Advantages of the resulting transparent conductor are indium‐free, vacuum‐free, and lithographic‐facility‐free, and metallic‐mask‐free, with small domain size (≈10 μm2), low sheet resistance (Rs < 1 Ω □−1), high optical transmittance (T > 80%), mechanical flexibility, and scalability, thus making it an excellent replacement for ITO.
All‐solution‐processed transparent conductive electrodes are obtained by integrating crackle photolithography‐based microwires with nanowires and electroplate welding. This combination results in scalable film structures that are flexible, indium‐free, vacuum‐free, lithographic‐facility‐free, metallic‐mask‐free, with small domain size, high optical transmittance, and low sheet resistance (one order of magnitude smaller than conventional nanowire‐based transparent conductors).
In this paper we present a study of pattern formation in bidimensional systems with competing short-range attractive and long-range repulsive interactions. The interaction parameters are chosen in ...such a way as to allow us to analyse two different situations: the spontaneous pattern formation due to the presence of strong competing interactions on different length scales and the pattern formation as a response to an external modulating potential when the system is close to its Lifshitz point. We compare different Monte Carlo techniques showing that the parallel tempering technique represents a promising approach for the study of such systems and we present detailed results for the specific heat and the structural properties. We also present random phase approximation predictions concerning spontaneous pattern formation (or microphase separation), as well as linear response theory predictions concerning the induced pattern formation due to the presence of an external modulating field. In particular we observe that the response of our systems to external fields is much stronger than the response of a Lennard-Jones fluid.
In the modern era, when prolonging life is not an option, the end-of-life discussions are unavoidably influenced by Neuroethics. Despite this, it is interestingly evident how the sentiments of a ...terminal patient of 1885 and a physician of 2020, are still comparable. This paper pre-sents the arguments behind the so-called "Therapeutic Misconception" and the aim of palliative care to provide dying patients support. It is essential to address priorities of informed consent, signed before any remedy is provided. A key component of the newest Neuroscience research is the analysis of motivation and free will. So, it is necessary to comprehend if the patient struggles to feel at peace with these aspects of his "right to die": Is he free to choose or is he influenced by the doctors? Is this confusion an example of "Therapeutic Misconception"? Is his Informed Consent totally "Informed"? In order to broaden our understanding, we account for many critical situations, such as the mentally impaired Psychiatric patients or the famous Italian case of Eluana Englaro. In addition, we suggested some current approaches such as Artificial Intelligence, useful in preserving some cognitive functions the patient may have lost. Furthermore, research in this field is very critical and in some Catholic countries like Italy, people faced difficulties accepting the idea of the "Anticipated directives". In general, whatever the mental status and whatever the terminal state, the patients seem still far from handling their own auto-determination and their Consent, even if the ultimate goal is to die with dignity.
This research describes the design and fabrication of an electromagnetic quadrupole installed inside a biaxial tensile test bench to induce magnetic field effects whose orientation can be adjusted to ...either 45° or 90° to develop magnetorheological elastomer (MRE) materials subjected to a biaxial stress condition. The objective of the quadrupole is to generate a homogeneous and oriented magnetic field in the central zone of the specimen. To achieve this, we used computational tools to simulate magnetic fields and applied the fundamentals of electrical machine design. The quadrupole can produce a uniform magnetic field ranging from 0 to 120 mT with a minimal gradient within the central area of the specimen. This feature allows us to comprehensively analyze the specimen under the influence of a uniform and controllable magnetic field. The quadrupole effectively aligns the microparticles within the polymeric matrix during the MRE curing process, resulting in a fractal structure with an average dimension of 1.78. While examining the MRE specimen's molecular structure, we observed fractal micro-particle clusters oriented at 45° and 90° from the positive x-axis. Because of the unexpected specimens' fractal molecular structures, we calculated their fractal dimension (FD-Avg), standard deviation (FD-Sd) and lacunarity (FD-Lac) to investigate a possible relationship between fractal dimensions and the specimens' physical properties. Consequently, we discovered that the molecular structure and physical properties, such as the shear modulus of the MRE specimens, are related to the resulting fractal dimensions using data collected from biaxial tests that consider material softening and its residual deformation effects. Our findings elucidate, for the first time, how the fractal dimension obtained from MRE specimens can be used to determine some of their physical properties.
•Novel design of an electromagnetic quadrupole capable of generating a homogeneous magnetic field.•Quadrupole core assembly optimized for biaxial testing with partial winding.•Excellent agreement between predicted and measured magnetic flux density.•Successful magnetic alignment in elastomer curing.•An expression that relates the fractal dimension of the MRE with the material static shear modulus was proposed.
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