Syntheses of second generation, 14-membered ring beta-turn mimics

Efficient solid phase syntheses of the constrained beta-turn peptidomimetics 1-3 were devised, and the conformational properties of three representative compounds in DMSO were determined.     

Probing single molecules and molecular aggregates: Raman spectroscopic advances

Development of Raman spectroscopy, profiting from surface‐enhanced Raman scattering and tip‐enhanced Raman scattering techniques, has inspired extensive research interest for trace analysis and dynamic measurements up to single‐molecule level. For another, Raman spectroscopy has also been recognized of significance in solving some important issues relating to molecule aggregates in chemistry and biology, owing to the capability of non‐destructive detection and high‐resolution fingerprints by which molecules and their aggregates can be identified. Herein, we summarize the recent progress of Raman spectroscopy in probing single molecules and molecular aggregates and block out a future prospective of Raman spectroscopy applied in cluster science. Copyright © 2015 John Wiley & Sons, Ltd.     

Importance of flue gas cooling conditions in particulate matter formation during biomass combustion under conditions pertinent to pulverized fuel applications

Laboratory-scale experiments pertinent to pulverised fuel (PF) combustion are often carried out in drop-tube furnaces (DTFs) at air-fuel equivalence ratios and cooling rate for quenching flue gas that are much higher than those in PF boilers. This paper reports the effect of flue gas cooling conditions on the properties of PM with aerodynamic diameter of <10 µm (PM₁₀) from biomass combustion. This study considers four cooling rates (1000, 2000, 6000 and 20,000 °C/s) and two biomass feeding rates (0.05 and 0.25 g/min) that represents flue gases with significantly-different concentrations of inorganic vapours. The PSDs of PM₁₀ have a bimodal distribution with a fine mode within PM with aerodynamic diameter of <1 µm (PM₁) and a coarse mode within PM with aerodynamic diameter of 1–10 µm (PM_1–10). All experimental conditions produce PM₁₀ with similar PM₁ and PM_1–10 yields (～0.8 and ～1.6 mg/g_biomass, respectively) and similar coarse mode diameters (i.e. 6.863 µm). However, at a biomass feeding rate of 0.05 g/min, the fine mode diameter shifts from 0.022 to 0.077 µm when the cooling rate decreases from 20,000 to 1000 °C/s, indicating more profound heterogeneous condensation at a lower cooling rate. As the biomass feeding rate increases to 0.25 g/min, the fine mode diameter further shifts to 0.043 µm and at 20,000 °C/s but remained at 0.077 µm at 1000 °C/s though a clear shift of PSD to larger diameters is evident. These are attributed to enhanced heterogeneous condensation and coagulation of small particulates resulting from increased particle population density in hot flue gas. Chemical analyses show PM₁ contains dominantly volatile elements (i.e. Na, K and Cl) while PM_1–10 consists of mainly Ca. Similar trends are also observed for elemental PSDs and yields. It is also observed that slow cooling of hot flue gas leads to an increased yield of Cl in PM_1–10 due to enhanced chlorination of Ca species.     

Characterization of cyclic triphosphenium ions in solution,and the crystal and molecular structure of 1,1,3,3‐tetraphenyl‐tetrahydro‐1,2,3‐triphosphenium hexachlorostannate

The preparation in solution of a number of cyclic triphosphenium ions and their identification by ³¹P NMR spectroscopy are described; the crystal and molecular structure of the six‐membered cationic ring (as its hexachlorostannate) has been determined. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:226–231, 2000     

Gas-Generating,pH-Responsive Calcium Carbonate Hybrid Particles with Biomimetic Coating for Contrast-Enhanced Ultrasound Imaging

This work reports the fabrication of biocompatible and pH-sensitive hybrid polydopamine/bovine serum albumin/calcium carbonate (PDA/BSA/CaCO₃) particles via a rapid precipitation method. These hybrid particles generate hyperechogenic carbon dioxide bubbles upon exposure to low pH environments, making them ideal as a contrast agent and detector for tumor cells. This study also highlights the application of red blood cell membrane (RBC)-derived membranes as a biomimetic coating for PDA/BSA/CaCO₃ hybrid particles in order to modulate protein corona formation, a natural physiological response that alters tailored properties of most nanomaterials that are administered systemically. Results of this work demonstrate that the RBC membrane-coated hybrid particles are ideal for a wide range of biomedical applications, such as noninvasive multimodal imaging, photothermal and photodynamic therapy, and “personalized” drug delivery systems.     

Cholinergic Chemotransmission and Anesthetic Drug Effects at the Carotid Bodies

General anesthesia is obtained by administration of potent hypnotics, analgesics and muscle relaxants. Apart from their intended effects (loss of consciousness, pain relief and muscle relaxation), these agents profoundly affect the control of breathing, in part by an effect within the peripheral chemoreflex loop that originates at the carotid bodies. This review assesses the role of cholinergic chemotransmission in the peripheral chemoreflex loop and the mechanisms through which muscle relaxants and hypnotics interfere with peripheral chemosensitivity. Additionally, consequences for clinical practice are discussed.     

Comparison of analytical strategies for EEG-correlated fMRI data in patients with epilepsy

The simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) can be used to localize interictal epileptiform discharges (IEDs). Previous studies have reported varying degrees of concordance of EEG-fMRI with electroclinical findings. The aim of the present study is to evaluate to what extent this variability is determined by the analytical strategy or by the properties of the EEG data. For that purpose, 42 IED sets obtained in 29 patients with epilepsy were reanalyzed using a finite impulse response approach, which estimates the hemodynamic response function (HRF) from the data and allows non-causal effects. Cardiac effects were treated as additional confounders in the model. This approach was compared to the classical approach assuming a fixed HRF for each voxel in the brain. The performance of each method was assessed by comparing the fMRI results to the EEG focus. The flexible model revealed more significantly activated voxels, which resulted in more activated brain regions concordant with the EEG focus (26 vs. 16). Correction for cardiac effects improved the results in 7 out of the 42 data sets. Furthermore, design theory for event-related experiments was applied in order to determine the influence of the number of IEDs and their temporal distribution on the success of an experiment. It appeared that this success is highly dependent upon the number of IEDs present during the recording and less on their temporal spacing. We conclude that the outcome of EEG-fMRI can be improved by using an optimized analytical strategy, but also depends on the number of IEDs occurring during the recording.     

Development of silicon purification by strong radiation catalysis method

Using a new type of solar furnace and a specially designed induction furnace,cost effective and highly efficient purification of metallurgical silicon into solar grade silicon can be achieved.It is realized by a new method for extracting boron from silicon with the aid of photo-chemical effect.In this article,we discussed the postulated principle of strong radiation catalysis and the recent development in practice.Starting from ordinary metallurgical silicon,we achieved a purification result of 0.12 ppmw to 0.3 ppmw of boron impurity in silicon by only single pass of a low cost and simple process,the major obstacle to make ’cheap’ solar grade silicon feedstock in industry is thus removed.