Molecular dynamics study of solubilization of cyclohexane,benzene, and phenol into mixed micelles composed of sodium dodecyl sulfate and octaethylene glycol monododecyl ether

Molecular dynamics calculations of a mixed micelle composed of sodium dodecyl sulfate (SDS) and octaethylene glycol monododecyl ether (C₁₂E₈) were performed for six compositions (SDS/C₁₂E₈ = 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100) to investigate the composition dependence of the mixed micelle structure and solubilization of cyclohexane, benzene, and phenol molecules by the micelle. The radial density distribution of the hydrophilic polyoxyethylene (POE) group of C₁₂E₈ as a function of distance from the micelle center is very sharp for micelles with high SDS content because the POE group captures a Na⁺ ion in solution and wraps around it to form a compact crown-ether-like complex. The hydrophobic dodecyl groups of SDS and C₁₂E₈ were separately distributed in the mixed micelle core. ΔG(r) evaluated for each solute showed that despite the structural changes of the micelle the binding strength of the solute molecules to the micelle did not change significantly. © 2019 Wiley Periodicals, Inc.     

Dynamic properties of angle-dependent high-order harmonic generation from coherently rotating molecules

High-order harmonic generation from coherently rotating N2 and O2 molecules has been observed for different alignment angles in a pump and probe experiment using femtosecond laser pulses. The results obtained are in excellent agreement with those calculated using a recently developed theory, which represent the characteristic properties predicted for angle-dependent harmonic generation. It is shown that polarization geometry and alignment distribution play essential roles in potential applications to probe electronic structure and dynamics of molecular systems.     

Developments of nano-polycrystalline diamond anvil cells for neutron diffraction experiments

ABSTRACT

A new high pressure cell for neutron diffraction experiments using nano-polycrystalline anvils is presented. The cell design, off-line pressure generation tests and a gas-loading procedure for this cell are described. The performance is illustrated by powder neutron diffraction patterns of ice VII to ～82?GPa. We also demonstrate the feasibility of single crystal neutron diffraction experiments of Fe₃O₄ at ambient conditions using this cell and discuss the current limitation and future developments.     

Fibrous and helical calcite crystals induced by synthetic polypeptides containing o-phospho-L-serine and o-phospho-L-threonine

The modification of CaCO(3) crystal growth by synthetic L-Ser(PO(3)H(2)) and L-Thr(PO(3)H(2)) containing polypeptides is described. The amino acids Gly, L-Glu, L-Asp, L-Ser, L-Ala, and L-Lys induced rhombohedral calcite with a rough surface. Dipeptides, Xaa-L-Ser(PO(3)H(2)) (Xaa = Gly, L-Glu, L-Asp, L-Ser, L-Ala and L-Lys) induced vaterite crystals in the lower [Ca(2+)]. On the other hand, L-Ser(PO(3)H(2))-containing polypeptides formed spherical vaterite and fibrous calcite. The characteristic helical calcite was found in the presence of copoly[L-Ser(PO(3)H(2))(75)L-Asp(25)] or poly[L-Ser(PO(3)H(2))(3)-L-Asp]. Fibrous calcite, spherical vaterite, and helical calcite crystals were subjected to XRD and EDX analysis. XRD revealed the specific faces of these crystals. EDX spectra and surface analysis visualized the localization of the polypeptides and CaCO(3) components. Together with TEM and SAED data, we propose hypothetical growth mechanisms for the fibrous and helical calcite crystals.     

Development of pyrrole-imidazole polyamide for specific regulation of human aurora kinase-A and -B gene expression

Pyrrole-imidazole polyamide (PIP) is a nuclease-resistant novel compound that inhibits gene expression through binding to the minor groove of DNA. Human aurora kinase-A (AURKA) and -B (AURKB) are important regulators in mitosis during the cell cycle. In this study, two specific PIPs (PIP-A and PIP-B) targeting AURKA and AURKB promoter regions were designed and synthesized, and their biological effects were investigated by several in vitro assays. PIP-A and PIP-B significantly inhibited the promoter activities, mRNA expression, and protein levels of AURKA and AURKB, respectively, in a concentration-dependent manner. Moreover, 1:1 combination treatment with both PIPs demonstrated prominent antiproliferative synergy (CI value [ED(50)] = 0.256) to HeLa cells as a result of inducing apoptosis-mediated severe catastrophe of cell-cycle progression. The novel synthesized PIP-A and PIP-B are potent and specific gene-silencing agents for AURKA and AURKB.     

Design of polymeric carriers for cancer-specific gene targeting: utilization of abnormal protein kinase Calpha activation in cancer cells

We succeeded in cancer cell specific gene expression by using a polyplex responsive to protein kinase Calpha, which is activated in various types of cancer cells.     

Total Synthesis and Biological Evaluation of (+)‐Neopeltolide and Its Analogues

The stereocontrolled total synthesis of the originally proposed ( 1 ) and correct ( 2 ) structures of (+)‐neopeltolide, a novel marine macrolide natural product with highly potent antiproliferative activity against several cancer cell lines as well as potent antifungal activity, has been achieved by exploiting a newly developed Suzuki–Miyaura coupling/ring‐closing metathesis strategy. Alkylborate 44 , which was generated in situ from iodide 34 , was coupled with enol phosphate 8 by a Suzuki–Miyaura coupling. Ring‐closing metathesis of the derived diene 45 followed by stereoselective hydrogenation afforded tetrahydropyran 47 as a single stereoisomer in high overall yield from 34 . Our convergent strategy enabled us to construct the 14‐membered macrolactone core structure of 2 in a rapid and efficient manner. Total synthesis and biological evaluation of synthetic intermediates and designed synthetic analogues, performed to establish the structure–activity relationships of 2 , led to the discovery of a structurally simple yet potent cytotoxic analogue, 9‐demethylneopeltolide ( 54 ).     

Simultaneous determination of tetracyclines and their degradation products in environmental waters by liquid chromatography–electrospray tandem mass spectrometry

A sensitive method was developed for the trace determination of six tetracyclines and ten of their degradation products in influent, effluent, and river waters using liquid chromatography–electrospray tandem mass spectrometry detection, combined with Oasis hydrophilic–lipophilic balance (HLB) cartridge extraction and Oasis mixed-mode strong anion exchange (MAX) cartridge cleanup. Tetracyclines and their products were separated by liquid chromatography in 9.5 min, and the instrument detection limits were generally between 0.03 and 0.1 μg/L except for minocycline (0.5 μg/L). The chromatograms were improved through the MAX cleanup and no apparent matrix effect was found. The recoveries of all the target compounds except for 4-epianhydrochlortetracycline and anhydrochlortetracycline (34–52%) were 75–120% for influent, 61–103% for effluent, and 64–113% for river waters. The method detection limits (MDLs) of the analytes varied in the range of 0.8–17.5 ng/L in all studied matrices. The method was applied for the determination of tetracyclines and their products in a sewage treatment plant (STP) and surface waters in Beijing, China. Oxytetracycline (3.8–72.5 ng/L), tetracycline (1.9–16.5 ng/L), and five products including 4-epitetracycline, 4-epioxytetracycline, isochlortetracycline, anhydrotetracycline, and 4-epianhydrochlortetracycline (5.7–25.3 ng/L) were detected in wastewater, while only oxytetracycline and tetracycline (2.2 and 2.1 ng/L) were detected in surface water samples.     

Electronic structure of BaTiO3 using resonant X-ray emission spectroscopy at the Ba-L3 and Ti-K absorption edges

We have studied the electronic properties of the ferroelectric barium titanate BaTiO₃ using two complementary bulk-sensitive spectroscopic probes, resonant X-ray emission spectroscopy (RXES) and X-ray absorption spectroscopy in the partial fluorescence mode (PFY-XAS) at the Ba-L₃ and Ti-K absorption edges. Contrary to a previous study, we found no fine structure in the pre-edge area of the PFY-XAS spectrum at the Ba-L₃ edge, and no temperature-induced spectral change was observed between room temperature and 150 °C. This result is not supportive of the possible presence of the displacement around Ba²⁺ at the Curie temperature. RXES spectra were measured at the Ti-K edge for BaTiO₃, along with SrTiO₃ and La-doped metallic SrTiO₃. The photon energy of the emission peak is found to be nearly constant throughout the absorption edge for all three compounds. We deduce the Ti 3d states to have a delocalized character, in contrast with the Ba 5d states, a property which is consistent with the proposed scenario of the formation of electric dipoles in BaTiO₃.     

Spectroscopic evidence for the unusual stereochemical configuration of an endosome-specific lipid

At a glance: The stereochemical configuration of the diglycerophosphate backbone of the endosome-specific lipid bis(monoacylglycero)phosphate (BMP, see picture) was determined by (1)H?NMR spectroscopy. Enantiomeric discrimination was facilitated by introduction of D-camphor ketals as chiral shift reagents, and enantiopure synthetic BMP analogues were prepared as reference materials. Natural BMP exhibited the unusual sn-1,1' diglycerophosphate backbone.