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Samuel Romano-Feinholz,1,* Alelí Salazar-Ramiro,2,* Emilio Muñoz-Sandoval,3 Roxana Magaña-Maldonado,2 Norma Hernández Pedro,4 Edgar Rangel López,5 Alberto González Aguilar,1 Aurora Sánchez García,6 Julio Sotelo,2 Verónica Pérez de la Cruz,7 Benjamín Pineda2 1Division of Neurosurgery, 2Neuroimmunology and Neuro-oncology Unit, National Institute of Neurology and Neurosurgery (NINN), Mexico City, 3Division of Advanced Materials, IPICYT, San Luis Potosí, 4Experimental Oncology Laboratory, National Cancer Institute of Mexico, 5Excitatory Aminoacids Laboratory, 6Pathology Laboratory, 7Neurochemistry Unit, National Institute of Neurology and Neurosurgery (NINN), Mexico City, Mexico *These authors contributed equally to this work Abstract: Despite multiple advances in the diagnosis of brain tumors, there is no effective treatment for glioblastoma. Multiwalled carbon nanotubes (MWCNTs), which were previously used as a diagnostic and drug delivery tool, have now been explored as a possible therapy against neoplasms. However, although the toxicity profile of nanotubes is dependent on the physicochemical characteristics of specific particles, there are no studies exploring how the effectivity of the carbon nanotubes (CNTs) is affected by different methods of production. In this study, we characterize the structure and biocompatibility of four different types of MWCNTs in rat astrocytes and in RG2 glioma cells as well as the induction of cell lysis and possible additive effect of the combination of MWCNTs with temozolomide. We used undoped MWCNTs (labeled simply as MWCNTs) and nitrogen-doped MWCNTs (labeled as N-MWCNTs). The average diameter of both pristine MWCNTs and pristine N-MWCNTs was ~22 and ~35 nm, respectively. In vitro and in vivo results suggested that these CNTs can be used as adjuvant therapy along with the standard treatment to increase the survival of rats implanted with malignant glioma. Keywords: carbon nanotubes, glioblastoma therapy, temozolomide, malignant glioma

The acetone contained in human breath is of great interest for the health sector as it is a marker that allows to diagnose and control diabetes in a non-invasive way. However, its concentration is extremely low. Therefore, high-performance acetone sensors are still a challenge. With this in mind, MgCo2O4 nanoparticles were synthesized using a microwave-assisted colloidal route with subsequent calcination. Structural and morphological characterizations were done through various techniques. The MgCo2O4 sensor was fabricated with the sample calcined at 500 °C. The sensing results showed that the sensor could detect acetone vapors ranging from 0.5 to 50 ppm at an optimum operating temperature of 250 °C with a high response, repeatability, stability, and selectivity. These sensing characteristics revealed that MgCo2O4 could be used as a new sensor material to detect acetone in exhaled human breath. [ABSTRACT FROM AUTHOR]

We investigate the magnetic behavior of Fe, Co, Ni, and permalloy nanomagnets using micromagnetic simulations. We propose a Reuleaux's triangle geometry shape for the individual nanomagnets. Reuleaux's triangle combines the equilateral triangle and circular geometry. The effects of varying the thickness (10, 20, and 40 nm) of these structures on the remanence magnetization and the coercive field are analyzed. Our results demonstrate that in most cases the hysteresis loops follow C, Ω, and vortex configurations in the magnetization reversal process. In addition, the magnetic properties of the small arrays of these nanomagnets are presented. [ABSTRACT FROM AUTHOR]

A tetrahedral magnetic cluster surrounded by metallic atoms is studied in the framework of the Hubbard model. The ground-state energy and the wave function are obtained exactly using the Lanczos numerical diagonalization method. The spin/spin correlation functions γij = (...) and the total spin S are analyzed as a function of the ratio between the on-site Coulomb repulsion U and electronic hopping t. [ABSTRACT FROM AUTHOR]

Resonating valence bond (RVB) states are fundamental for understanding quantum spin liquids in two-dimensional (2D) systems. The RVB state is a collective phenomenon in which spins are uncoupled. 2D lattices such as triangular, honeycomb, and dice lattices were investigated using the Hubbard model and exact diagonalization method. We analyzed the total spin, spin-spin correlation functions, local magnetic moments, and spin and charge gaps as a function of on-site Coulomb repulsion, electron concentration, and electronic hopping parameters. Phase diagrams showed that RVB states can live in half-filled and hole-doped anisotropic triangular lattices. We found two types of RVB states: one in the honeycomb sublattice and the other in the centered hexagons in the triangular lattices. Owing to the novel discovery of exotic magnetic ordering in triangular moiré patterns in twisted bilayer graphene and transition metal dichalcogenide systems, our results provide physical insights into the onset of magnetism and possible spin liquid states in these layered materials., (Creative Commons Attribution license.)

A quantum spin liquid (QSL) is a state of matter in which spins do not exhibit magnetic order. In contrast to paramagnets, the spins in a QSL interact strongly, similar to conventional ordered magnets; however the thermodynamic stability of QSLs is rarely studied. Here, the thermodynamic properties of centered hexagon nanoclusters were investigated using the Hubbard model, which was solved using exact numerical diagonalization. The total spin, spin-spin correlation functions, local magnetic moments, charge and spin gaps, and magnetocaloric effect were analyzed for a half-filled band as a function of the ratio between the on-site Coulomb repulsion and electronic hopping ( U / t ). The centered hexagon nanocluster exhibited an antiferromagnetic (AFM) behavior with exotic magnetic ordering. Resonating-valence-bond (RVB) states were observed for intermediate values of U / t , in which short-range spin-spin correlation functions were suppressed to minimize spin frustration. The AFM order was examined in terms of the Néel-like temperature derived from the temperature dependence of the magnetic susceptibility. An interesting result is that the systems under external magnetic fields exhibited an inverse magnetocaloric effect, which was remarkable for intermediate values of U / t , where the RVB state was observed. Owing to the novel discovery of exotic magnetic ordering in triangular moiré patterns in twisted bilayer graphene (TBLG) systems, these results provide insights into the onset of magnetism and the possible spin liquid states in these graphene moiré materials.

The sensing of harmful gases and vapors is of fundamental interest to control the industrial emissions and environmental contamination. Nitrogen/phosphorus codoped carbon nanotube sponges (NP-CNTSs) were used to detect ethanol, acetone, cyclohexane, isopropanol, and methanol. The NP-CNTSs were produced through the aerosol-assisted chemical vapor deposition (AACVD) method using acetonitrile and triphenylphosphine as precursors at 1020 °C. The sensors based on NP-CNTSs were tested with varying operating temperatures (25-100 °C) and gas vapor concentrations (5-50 ppm). For instance, for a gas vapor concentration of 30 ppm and an operating temperature of 65 °C, the sensors showed changes in the electrical resistance of 1.12%, 1.21%, 1.09%, 2.4%, and 1.34% for ethanol, acetone, cyclohexane, isopropanol, and methanol, respectively. We found that the response and recovery times for isopropanol gas vapor are up to 43.7 s and 95 s, respectively. The current sensor outperformed the sensors reported in the literature by at least two times in the response measurement. Additionally, we performed van der Waals density functional theory calculations to elucidate the role of nitrogen and phosphorous codoped single-walled carbon nanotubes (SWCNTs) and their interaction with the considered gas molecule. We analyzed the molecular adsorption energy, optimized structures, and the density of states and calculated the electrostatic potential surface for N-doped, P-doped, NP-codoped, and OH-functionalized NP-codoped metallic SWCNTs-(6,6) and semiconducting SWCNTs-(10,0). Adsorption energy calculations revealed that in most cases the molecules are adsorbed to carbon nanotubes via physisorption. The codoping in SWCNTs-(6,6) promoted structural changes in the surface nanotube and marked chemisorption for acetone molecules.

Calcium oxalate (CaOx) crystals in plants are formed in crystal idioblasts cells and have specific geometric shapes. Their proposed functions include calcium homeostasis and carbon source, among others. Amaranth is a plant that presents high tolerance to abiotic stresses and accumulates considerable amounts of CaOx crystals; however, few studies have focused on characterizing the crystals ultrastructure and none is related to identifying proteins bound to them. This information is of great interest to understand the mechanisms related to CaOx crystal formation and to support their proposed functions. Thus, this work aimed to characterize CaOx crystals in amaranth leaves. Crystals were purified and the proteins bound to them were isolated and identified by nLC-MS/MS. Leaf sections were analyzed by light and electron microscopy. The identified proteins were related to the chloroplast such as ATPb synthase, RuBisCO large subunit, and cell wall-related proteins, which were validated by immunohistochemistry and immunogold labeling. In addition, it was observed that CaOx crystal idioblasts were formed from parenchyma cells associated with mesophyll and veins, in which the thylakoid membranes of degraded chloroplasts turned into crystal chambers. These results significantly advance our understanding of the mechanisms of CaOx crystal formation and the potential function as an alternative carbon source in leaves., (© 2022 Wiley Periodicals LLC.)