1,8-Naphthyridines. Part III. Synthesis of some 6-substituted-1,8-naphthyridin-2(1H)ones

The syntheses of some 1,8-naphthyridines substituted in the 6-position with heterocyclic groups are described. A synthetic route to 6-amino-5,7-dimethyl-1,8-naphthyridin-2(1H)one is also presented.     

Challenges and strategies in the preparation of large‐volume polymer‐based monolithic chromatography adsorbents

To date, the number of published reports on the large‐volume preparation of polymer‐based monolithic chromatography adsorbents is still lacking and is of great importance. Many critical factors need to be considered when manufacturing a large‐volume polymer‐based monolith for chromatographic applications. Structural integrity, validity, and repeatability are thought to be the key factors determining the usability of a large‐volume monolith in a separation process. In this review, we focus on problems and solutions pertaining to heat dissipation, pore size distribution, “wall channel” effect, and mechanical strength in monolith preparation. A template‐based method comprising sacrificial and nonsacrificial techniques is possibly the method of choice due to its precise control over the porous structure. However, additional expensive steps are usually required for the template removal. Other strategies in monolith preparation are also discussed.     

ACQ-to-AIE Transformation: Tuning Molecular Packing by Regioisomerization for Two-Photon NIR Bioimaging

The traditional design strategies for highly bright solid-state luminescent materials rely on weakening the intermolecular π–π interactions, which may limit diversity when developing new materials. Herein, we propose a strategy of tuning the molecular packing mode by regioisomerization to regulate the solid-state fluorescence. TBP-e-TPA with a molecular rotor in the end position of a planar core adopts a long-range cofacial packing mode, which in the solid state is almost non-emissive. By shifting molecular rotors to the bay position, the resultant TBP-b-TPA possesses a discrete cross packing mode, giving a quantum yield of 15.6±0.2 %. These results demonstrate the relationship between the solid-state fluorescence efficiency and the molecule's packing mode. Thanks to the good photophysical properties, TBP-b-TPA nanoparticles were used for two-photon deep brain imaging. This molecular design philosophy provides a new way of designing highly bright solid-state fluorophores.     

Stress-enhanced transport of toluene in poly aryl ether ether ketone (PEEK)

The transport of fluids in the semicrystalline polymer, poly(aryl ether ether ketone) (PEEK), was investigated. Both solubility and rate of penetration of toluene into PEEK are markedly increased by the application of an external stress. The induction period (i.e., the time for the sorption to begin) is a function of applied stress as well as temperature and crystallinity. At 22°C in 29% crystalline PEEK the induction period was reduced from more than 2000 h to approximately 10 h whereas the solubility of toluene was increased from 9 to 44 wt % upon the application of an external tensile stress of 30 MPa. A critical stress (i.e., a stress value below which the stress-enhanced effects are not observed) was determined. The critical stress is a strong function of crystallinity and temperature. © 1996 John Wiley & Sons, Inc.     

Metabolic compartmentalization in the human cortex and hippocampus: evidence for a cell- and region-specific localization of lactate dehydrogenase 5 and pyruvate dehydrogenase

Background  

For a long time now, glucose has been thought to be the main, if not the sole substrate for brain energy metabolism. Recent data nevertheless suggest that other molecules, such as monocarboxylates (lactate and pyruvate mainly) could be suitable substrates. Although monocarboxylates poorly cross the blood brain barrier (BBB), such substrates could replace glucose if produced locally.     

Apparate zur Wasseruntersuchung

Ohne Zusammenfassung     

The application of quantum chemistry and condensed matter theory in studying amino-acids, protein folding and anticancer drug technology

The adaptation of methods from quantum chemistry and condensed matter theory for studying biological molecules has proved fruitful in developing our understanding of the electronic and conformational structure and thereby the functionality of amino-acids and proteins. Professor Suhai has been at the forefront of these developments and has made contributions in many areas of this vast field of research. In this article, we focus on three such areas, namely, (1) amino acids, (2) bacteriorhodopsin and (3) anti-cancer drugs involving especially Ru and Rh. We show how advances in density functional theory (DFT) have been used to calculate the electronic structure and density in amino-acids so that they can be compared with X-ray diffraction studies. We also demonstrate how ideas from the theory of phase transitions in condensed matter may be applied for studying phase transitions in bacteriorhodopsin, DNA and proteins. Finally, we highlight some of the recent work done in bringing DFT together with quantum chemistry modelling in studying metallopharmaceutical complexes and conformations of peptides.     

Synthesis of a new hydrophilic poly(ethylene glycol)-ionic liquid and its application in peptide synthesis

The synthesis of a new hydrophilic ammonium-based poly(ethylene glycol)-ionic liquid (PEG-IL) is reported; the structure was assigned by NMR ((1)H, (13)C) and MALDI mass spectrometry. The viscosity and thermal stability were also studied, as well as its polarity. Its application as an alternative solvent in the synthesis of dipeptides under microwave irradiation is also described.     

Quantitative imaging of equivalence ratios in a natural gas SI engine flow bench using acetone fluorescence

Although compressed natural gas (CNG) is a gaseous fuel, the mixing process is quite different from air-liquid fuel mixing. The aim of this work is to understand the effect of the fuel feeding system on mixture homogeneity. Planar laser-induced fluorescence has been used to produce quantitative equivalence ratio maps in the intake manifold. Fluorescence results from excitation of doped acetone in natural gas. Its emission is proportional to the fuel mass. Collected images were post processed to obtain the equivalence ratio. This work shows the difference between continuous injection at low speed and sequential injection. In the first part, we present the behaviour of the injection jet in the intake manifold. The second part displays a smaller section of the duct upstream of the intake valve. The study shows clearly the stratification effect obtained with continuous injection at low speed. A very homogenous mixture is observed for sequential injection with fuel trapped for a cycle and aspirated in the next cycle.     

Solvent-induced crystallinity in poly(aryl-ether-ether-ketone) [PEEK]

The amount and structure of the crystals formed by the solvent-induced crystallization (SIC) following a sorption-desorption cycle of five fluids (benzene, toluene, chloroform, methylene chloride, and carbon disulfide) in amorphous PEEK was determined by wideangle x-ray scattering (WAXS). The SIC crystal structure was compared with that produced by thermal methods, both those formed at low temperature by heating the amorphous material 10–20°C above T_g or by cooling from the melt. Although smaller in size, the SIC crystals are tighter and more organized than those produced thermally. The WAXS data indicates that all five fluids produce approximately 35% crystallinity in PEEK. Gravimetric data suggest that a low-density region, consisting of either microvoids or highly disordered amorphous region, surrounds the crystals.