Thermodynamic approach to boron nitride nanotube solubility and dispersion

Inadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to improve dispersion include surface functionalization, surfactants, polymer wrapping, and sonication. Although these approaches have proven effective, they often achieve dispersion by altering the surface or structure of the nanomaterial and ultimately, their intrinsic properties. Co-solvents are commonly utilized in the polymer, paint, and art conservation industries to selectively dissolve materials. These co-solvents are utilized based on thermodynamic interaction parameters and are chosen so that the original materials are not affected. The same concept was applied to enhance the dispersion of boron nitride nanotubes (BNNTs) to facilitate the fabrication of BNNT nanocomposites. Of the solvents tested, dimethylacetamide (DMAc) exhibited the most stable, uniform dispersion of BNNTs, followed by N,N-dimethylformamide (DMF), acetone, and N-methyl-2-pyrrolidone (NMP). Utilizing the known Hansen solubility parameters of these solvents in comparison to the BNNT dispersion state, a region of good solubility was proposed. This solubility region was used to identify co-solvent systems that led to improved BNNT dispersion in poor solvents such as toluene, hexane, and ethanol. Incorporating the data from the co-solvent studies further refined the proposed solubility region. From this region, the Hansen solubility parameters for BNNTs are thought to lie at the midpoint of the solubility sphere: 16.8, 10.7, and 9.0 MPa(1/2) for δd, δp, and δh, respectively, with a calculated Hildebrand parameter of 21.8 MPa(1/2).

Solid-state polymerization of EDTA and ethylenediamine as one-step approach to monodisperse hyperbranched polyamides

Hyperbranched polyamides (HBPAs), a special class of polymers with extended use in colloidal systems, is synthesized by an innovative method taking advantage of the ordered aggregation of positive and negative molecular ions in solid-state.

Development of a linear induction motor based artificial muscle system

We present the design of a linear induction motor based on electromagnetic interactions. The engine is capable of producing a linear movement from electricity. The design consists of stators arranged in parallel, which produce a magnetic field sufficient to displace a plunger along its axial axis. Furthermore, the winding has a shell and cap of ferromagnetic material that amplifies the magnetic field. This produces a force along the length of the motor that is similar to that of skeletal muscle. In principle, the objective is to use the engine in the development of an artificial muscle system for prosthetic applications, but it could have multiple applications, not only in the medical field, but in other industries.

New trends in computational modeling: a Neuroid-based retina model

It is thought that using detailed neuron-models could lead to a better understanding of how the nervous system works. However, neural networks preserve their collective computational properties, regardless of the level of description used for modeling the main building block. In this paper, we built a Neuroid-based retina model. As a result of the implementation, the Neuroid was able to reproduce the essential features of the photoreceptor response to light. Likewise, the retina model responded to specific visual effects such as simultaneous contrast, Mach bands and Hermann grid. All of these suggest that the Neuroid comprises enough functional characteristics, such that we could focus not only on the most relevant computational aspects of nerve cells, but also in the collective capabilities of large-scale neural networks.

The heritable path of human physical performance: from single polymorphisms to the "next generation"

Human physical performance is a complex multifactorial trait. Historically, environmental factors (e.g., diet, training) alone have been unable to explain the basis of all prominent phenotypes for physical performance. Therefore, there has been an interest in the study of the contribution of genetic factors to the development of these phenotypes. Support for a genetic component is found with studies that shown that monozygotic twins were more similar than were dizygotic twins for many physiological traits. The evolution of molecular techniques and the ability to scan the entire human genome enabled association of several genetic polymorphisms with performance. However, some biases related to the selection of cohorts and inadequate definition of the study variables have complicated the already difficult task of studying such a large and polymorphic genome, often resulting in inconsistent results about the influence of candidate genes. This review aims to provide a critical overview of heritable genetic aspects. Novel molecular technologies, such as next-generation sequencing, are discussed and how they can contribute to improving understanding of the molecular basis for athletic performance. It is important to ensure that the large amount of data that can be generated using these tools will be used effectively by ensuring well-designed studies.

Reply to "Comment on 'Third law of thermodynamics as a key test of generalized entropies' "

In Bento et al. [Phys. Rev. E 91, 039901 (2015)] we develop a method to verify if an arbitrary generalized statistics does or does not obey the third law of thermodynamics. As examples, we address two important formulations, Kaniadakis and Tsallis. In their Comment on the paper, Bagci and Oikonomou suggest that our examination of the Tsallis statistics is valid only for q≥1, using arguments like there is no distribution maximizing the Tsallis entropy for the interval q<0 (in which the third law is not verified) compatible with the problem energy expression. In this Reply, we first (and most importantly) show that the Comment misses the point. In our original work we have considered the now already standard construction of the Tsallis statistics. So, if indeed such statistics lacks a maximization principle (a fact irrelevant in our protocol), this is an inherent feature of the statistics itself and not a problem with our analysis. Second, some arguments used by Bagci and Oikonomou (for 0<q<1) reflect a misunderstanding of our explicit calculations. These arguments are then clarified under our approach and illustrated through a simple two-level system.

In vitro neurotoxicity evaluation of piperazine designer drugs in differentiated human neuroblastoma SH-SY5Y cells

Abuse of synthetic drugs is widespread worldwide. Studies indicate that piperazine designer drugs act as substrates at dopaminergic and serotonergic receptors and/or transporters in the brain. This work aimed to investigate the cytotoxicity of N-benzylpiperazine, 1-(3-trifluoromethylphenyl)piperazine, 1-(4-methoxyphenyl)piperazine and 1-(3,4-methylenedioxybenzyl)piperazine in the differentiated human neuroblastoma SH-SY5Y cell line. Cytotoxicity was evaluated after 24 h incubations through the MTT reduction and neutral red uptake assays. Oxidative stress (reactive oxygen and nitrogen species production and glutathione content) and energetic (ATP content) parameters, as well as intracellular Ca(2+), mitochondrial membrane potential, DNA damage (comet assay) and cell death mode were also evaluated. Complete cytotoxicity curves were obtained after 24 h incubations with each drug. A significant decrease in intracellular total glutathione content was noted for all the tested drugs. All drugs caused a significant increase of intracellular free Ca(2+) levels, accompanied by mitochondrial hyperpolarization. However, ATP levels remained unchanged. The investigation of cell death mode revealed a predominance of early apoptotic cells. No genotoxicity was found in the comet assay. Among the tested drugs, 1-(3-trifluoromethylphenyl)piperazine was the most cytotoxic. Overall, piperazine designer drugs are potentially neurotoxic, supporting concerns on risks associated with the abuse of these drugs.