Irreversible thermodynamics of non-uniform insulating ferromagnets

Two types of damping are commonly applied to describe ferromagnets at the phenomenological level: one by Landau and Lifshitz, and the other by Gilbert. This work successively applies the methods of irreversible thermodynamics to insulators, insulating paramagnets, and uniform insulating ferromagnets, in the last case uniquely obtaining Landau–Lifshitz damping. These methods are then applied to non-uniform insulating ferromagnets, for which new, non-current-related, spin fluxes and spin torques appear. These may be relevant to the dynamics of magnets in confined geometries, where boundary conditions impose complex non-trivial textures. Study of systems with very large damping might help distinguish between the two proposed forms of damping.     

The double-soft integral for an arbitrary angle between hard radiators

We consider the double-soft limit of a generic QCD process involving massless partons and integrate analytically the double-soft eikonal functions over the phase-space of soft partons (gluons or quarks) allowing for an arbitrary relative angle between the three-momenta of two hard massless radiators. This result provides one of the missing ingredients for a fully analytic formulation of the nested soft-collinear subtraction scheme described in Caola et al. (Eur Phys J C 77(4):248, 2017).     

Equation of state of boron subarsenide B12As2 to 47 GPa

Compressibility of boron subarsenide B₁₂As₂ has been studied by synchrotron X-ray diffraction up to 47?GPa at room temperature in a diamond anvil cell using Ne pressure transmitting medium. A fit of experimental p–V data by Vinet equation of state yielded the bulk modulus of 150(4) GPa and its first pressure derivative of 6.4(3). No pressure-induced phase transitions have been observed.     

Computational-Based Discovery of the Anti-Cancer Activities of Pyrrole-Based Compounds Targeting the Colchicine-Binding Site of Tubulin

Despite the tubulin-binding agents (TBAs) that are widely used in the clinic for cancer therapy, tumor resistance to TBAs (both inherited and acquired) significantly impairs their effectiveness, thereby decreasing overall survival (OS) and progression-free survival (PFS) rates, especially for the patients with metastatic, recurrent, and unresectable forms of the disease. Therefore, the development of novel effective drugs interfering with the microtubules’ dynamic state remains a big challenge in current oncology. We report here about the novel ethyl 2-amino-1-(furan-2-carboxamido)-5-(2-aryl/tert-butyl-2-oxoethylidene)-4-oxo-4,5-dihydro-1H-pyrrole-3-carboxylates (EAPCs) exhibiting potent anti-cancer activities against the breast and lung cancer cell lines in vitro. This was due to their ability to inhibit tubulin polymerization and induce cell cycle arrest in M-phase. As an outcome, the EAPC-treated cancer cells exhibited a significant increase in apoptosis, which was evidenced by the expression of cleaved forms of PARP, caspase-3, and increased numbers of Annexin-V-positive cells. By using the in silico molecular modeling methods (e.g., induced-fit docking, binding metadynamics, and unbiased molecular dynamics), we found that EAPC-67 and -70 preferentially bind to the colchicine-binding site of tubulin. Lastly, we have shown that the EAPCs indicated above and colchicine utilizes a similar molecular mechanism to inhibit tubulin polymerization via targeting the T7 loop in the β-chain of tubulin, thereby preventing the conformational changes in the tubulin dimers required for their polymerization. Collectively, we identified the novel and potent TBAs that bind to the colchicine-binding site and disrupt the microtubule network. As a result of these events, the compounds induced a robust cell cycle arrest in M-phase and exhibited potent pro-apoptotic activities against the epithelial cancer cell lines in vitro.     

Synthesis of ONO-Ligated Tetrylenes Based on 2,6-bis(2-Hydroxyphenyl)pyridines: Influence of Ligand Sterics on the Structure of the Products

A series of novel tetrylenes based on three 2,6-bis(2-hydroxyphenyl)pyridines 4 a – 4 c have been obtained by the reaction of Lappert's tetrylenes E[N(SiMe₃)₂]₂ (E=Ge, Sn) with corresponding tridentate pyridine-linked phenol-based ligands. It was found that the structure of the ligand and the size of the atom of the group 14 element drastically affect the structure of the reaction product. Ligand 4 c with a bulky tert-butyl group leads to monomeric tetrylenes, while ligands with less bulky groups lead to bis-ligand derivatives of M(IV) (M=Ge, Sn) and a coordination polymer. Also, derivatives of germanium (IV) and tin (IV) were obtained by the metathesis reaction of MCl₄ (M=Ge, Sn) with lithium phenoxides. The compositions and structures of the novel compounds were established by elemental analysis and ¹H, ¹³C, ¹¹⁹Sn ( 5 – 7 ), ¹H DOSY ( 6 ) NMR spectroscopy, in the solid state by X-ray diffraction analysis (germylene 10 , stannylene 6 , Ge⁴⁺ compound 8 , Sn⁴⁺ compound 7 ) and ¹¹⁹Sn Mössbauer spectrum of tin complex 6 . All the synthesized tetrylenes are monomeric. Tetrylenes 6 and 10 were characterized by cyclic voltammetry. A study of the redox behavior of 6 , 10 by cyclic voltammetry on a glassy carbon working electrode in acetonitrile solution of 0.1 M Bu₄NPF₆ as a supporting electrolyte showed that these compounds can be both oxidized and reduced electrochemically in the accessible potential range.     

High-Porosity Metal-Organic Framework Glasses

We report a synthetic strategy to link titanium-oxo (Ti-oxo) clusters into metal-organic framework (MOF) glasses with high porosity though the carboxylate linkage. A new series of MOF glasses was synthesized by evaporation of solution containing Ti-oxo clusters Ti₁₆O₁₆(OEt)₃₂, linkers, and m-cresol. The formation of carboxylate linkages between the Ti-oxo clusters and the carboxylate linkers was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. The structural integrity of the Ti-oxo clusters within the glasses was evidenced by both X-ray absorption near edge structure (XANES) and ¹⁷O magic-angle spinning (MAS) NMR. After ligand exchange and activation, the fumarate-linked MOF glass, termed Ti-Fum, showed a N₂ Brunauer–Emmett–Teller (BET) surface areas of 923 m² g⁻¹, nearly three times as high as the phenolate-linked MOF glass with the highest BET surface area prior to this report.     

Recent advances in laser self-injection locking to high-Q microresonators

The stabilization and manipulation of laser frequency by means of an external cavity are nearly ubiquitously used in fundamental research and laser applications. While most of the laser light transmits through the cavity, in the presence of some back-scattered light from the cavity to the laser, the self-injection locking effect can take place, which locks the laser emission frequency to the cavity mode of similar frequency. The self-injection locking leads to dramatic reduction of laser linewidth and noise. Using this approach, a common semiconductor laser locked to an ultrahigh-Q microresonator can obtain sub-Hertz linewidth, on par with state-of-the-art fiber lasers. Therefore it paves the way to manufacture high-performance semiconductor lasers with reduced footprint and cost. Moreover, with high laser power, the optical nonlinearity of the microresonator drastically changes the laser dynamics, offering routes for simultaneous pulse and frequency comb generation in the same microresonator. Particularly, integrated photonics technology, enabling components fabricated via semiconductor CMOS process, has brought increasing and extending interest to laser manufacturing using this method. In this article, we present a comprehensive tutorial on analytical and numerical methods of laser self-injection locking, as well a review of most recent theoretical and experimental achievements.     

Tailorable and Biocompatible Supramolecular-Based Hydrogels Featuring two Dynamic Covalent Chemistries

Dynamic covalent chemistry (DCC) has proven to be a valuable tool in creating fascinating molecules, structures, and emergent properties in fully synthetic systems. Here we report a system that uses two dynamic covalent bonds in tandem, namely disulfides and hydrazones, for the formation of hydrogels containing biologically relevant ligands. The reversibility of disulfide bonds allows fiber formation upon oxidation of dithiol-peptide building block, while the reaction between NH−NH₂ functionalized C-terminus and aldehyde cross-linkers results in a gel. The same bond-forming reaction was exploited for the “decoration” of the supramolecular assemblies by cell-adhesion-promoting sequences (RGD and LDV). Fast triggered gelation, cytocompatibility and ability to “on-demand” chemically customize fibrillar scaffold offer potential for applying these systems as a bioactive platform for cell culture and tissue engineering.