Simple approach to estimating the van der Waals interaction between carbon nanotubes

The van der Waals (vdW) interactions between carbon nanotubes (CNTs) were studied based on the continuum Lennard-Jones model. It was found that all the vdW potentials between two arbitrary CNTs fall on the same curve when plotted in terms of certain reduced parameters, the well depth, and the equilibrium vdW gap. Based on this observation, an approximate approach is developed to obtain the vdW potential between two CNTs without time-consuming computations. The vdW potential estimated by this approach is close to that obtained from complex integrations. Therefore, the developed approach can greatly simplify the calculation of vdW interactions between CNTs

Negative Magnetoresistance in Dirac Semimetal Cd3As2

A large negative magnetoresistance is anticipated in topological semimetals in the parallel magnetic and electric field configuration as a consequence of the nontrivial topological properties. The negative magnetoresistance is believed to demonstrate the chiral anomaly, a long-sought high-energy physics effect, in solid-state systems. Recent experiments reveal that Cd3As2, a Dirac topological semimetal, has the record-high mobility and exhibits positive linear magnetoresistance in the orthogonal magnetic and electric field configuration. However, the negative magnetoresistance in the parallel magnetic and electric field configuration remains unveiled. Here, we report the observation of the negative magnetoresistance in Cd3As2 microribbons in the parallel magnetic and electric field configuration as large as 66% at 50 K and even visible at room temperatures. The observed negative magnetoresistance is sensitive to the angle between magnetic and electrical field, robust against temperature, and dependent on the carrier density. We have found that carrier densities of our Cd3As2 samples obey an Arrhenius's law, decreasing from 3.0x10^17 cm^-3 at 300 K to 2.2x10^16 cm^-3 below 50 K. The low carrier densities result in the large values of the negative magnetoresistance. We therefore attribute the observed negative magnetoresistance to the chiral anomaly. Furthermore, in the perpendicular magnetic and electric field configuration a positive non-saturating linear magnetoresistance up to 1670% at 14 T and 2 K is also observed. This work demonstrates potential applications of topological semimetals in magnetic devices

Pharmacokinetics and Brain Uptake of an IgG-TNF Decoy Receptor Fusion Protein Following Intravenous, Intraperitoneal, and Subcutaneous Administration in Mice

Tumor necrosis factor (TNF)-α is a proinflammatory cytokine active in the brain. Etanercept, the TNF decoy receptor (TNFR), does not cross the blood–brain barrier (BBB). The TNFR was re-engineered for BBB penetration as a fusion protein with a chimeric monoclonal antibody (mAb) against the mouse transferrin receptor (TfR), and this fusion protein is designated cTfRMAb-TNFR. The cTfRMAb domain of the fusion protein acts as a molecular Trojan horse and mediates transport via the endogenous BBB TfR. To support future chronic treatment of mouse models of neural disease with daily administration of the cTfRMAb-TNFR fusion protein, a series of pharmacokinetics and brain uptake studies in the mouse was performed. The cTfRMAb-TNFR fusion protein was radiolabeled and injected into mice via the intravenous, intraperitoneal (IP), or subcutaneous (SQ) routes of administration at doses ranging from 0.35 to 10 mg/kg. The distribution of the fusion protein into plasma following the IP or SQ routes was enhanced by increasing the injection dose from 3 to 10 mg/kg. The fusion protein demonstrated long circulation times with high metabolic stability following the IP or SQ routes of injection. The IP or SQ routes produced concentrations of the cTfRMAb-TNFR fusion protein in the brain that exceed by 20- to 50-fold the concentration of TNFα in pathologic conditions of the brain. The SQ injection is the preferred route of administration, as the level of cTfRMAb fusion protein produced in the brain is comparable to that generated with intravenous injection, and at a much lower plasma area under the concentration curve of the fusion protein as compared to IP administration

Tris(piperazinediium) phosphatododeca­molybo(V,VI)phosphate

The title compound, (C4H12N2)3[PMo12O40] or (H2pip)3[PMo12O40] (pip is piperazine), was prepared under hydro­thermal conditions. The asymmetric unit contains one-sixth of a mixed-valent Mo(V,VI) pseudo-Keggin-type [PMo12O40]6− anion and half a piperazinediium cation, (H2pip)2+. The discrete Keggin-type [PMo12O40]6- anion has site symmetry and the three (H2pip)2+ cations each have site symmetry at the centres of the mol­ecules. The central P atom is on special position , which is a roto-inversion position and generates the disorder of the PO4 tetra­hedron. Furthermore, six doubly bridging oxide groups are also disordered with an occupancy factor of 0.5 for each O atom. The anions and cations are linked by an extensive network of inter­molecular N—H⋯O and C—H⋯O hydrogen bonds