Variation of Brominated Indoles and Terpenoids Within Single and Different Colonies of the Marine Bryozoan Flustra foliacea

The variation of the brominated indole and diterpenoid content within single and different colonies of the bryozoan Flustra foliacea was investigated. The secondary metabolite profile and concentrations of individual components of F. foliacea samples were established using GC-MS. Samples from 17 different collecting sites were analyzed. The alkaloid and diterpene composition of F. foliacea varied greatly depending upon the site of collection. Investigation of F. foliacea samples from a single site (Helgoland, North Sea) over a period of time showed that the alkaloid and diterpenoid profile remained constant, however concentrations of individual components varied significantly. The alkaloid and diterpenoid composition of different segments of a single colony was found to be constant. Only small differences could be detected in the essential oil composition of different colonies and segments of single colonies of F. foliacea. Two of the F. foliacea alkaloids were found in the gastropods Hydrobia ulva and Gibbula cinerea, and one alkaloid in the common starfish Asteria rubens, all collected from the surface of the bryozoan.     

Singlet oxygen microscope: from phase-separated polymers to single biological cells

The lowest excited electronic state of molecular oxygen, singlet molecular oxygen (a1Deltag), is an intermediate in many chemical and biological processes. Tools and methods have been developed to create singlet-oxygen-based optical images of heterogeneous samples that range from phase-separated polymers to biological cells. Such images provide unique insight into a variety of oxygen-dependent phenomena, including the photoinitiated death of cells.     

Erosion behavior of EB-PVD 7YSZ coatings under corrosion/erosion regime: Effect of TBC microstructure and the CMAS chemistry

Aero-engines operating in dust-laden environments often encounter a lot of dust/sand that causes a severe problem to the TBCs by means of erosion. As the turbine entry temperatures are rising, molten sand is also a big concern to the life-time of TBCs.This paper deals with the TBC behavior under the combined influence of erosion and corrosion attack. Variations in TBC morphology, CMAS infiltration time and CMAS composition and their influence on the erosion resistance at room temperature were investigated. Two different EB-PVD 7YSZ morphologies consisting of a different porosity arrangement were tested in the erosion/corrosion regime. The more ‘Feathery’ structure has a better resistance to erosion compared to a more columnar ‘Normal’ structure, which leads to less degradation of the TBC. However, under the influence of CMAS infiltration the effect was found to be reversed. In general, CMAS-infiltrated EB-PVD TBCs exhibit a higher erosion resistance than the non-infiltrated ones.     

Combined TPS, XPS, EXAFS, and NO-TPD study of the sulfiding of Mo/Al2O3

The sulfiding of Mo/Al₂O₃ in H₂S/Ar versus in H₂S/H₂ has been studied by temperature-programmed sulfiding (TPS), X-ray photon electron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and temperature-programmed desorption of NO (NO-TPD). All the applied techniques agree on the sulfur content in the sulfided catalysts and the findings are in accord with a model for the H₂S production reaction. The nucleation and growth of well-ordered MoS₂ clusters are probed by XPS during sulfiding with and without the presence of hydrogen. The resulting dispersion of the MoS₂ phase is evaluated on the basis of XPS, EXAFS, and NO-TPD, and is found to be highest when the sulfiding occurs in the presence of hydrogen.     

Aggregation‐Prone Amyloid‐β⋅CuII Species Formed on the Millisecond Timescale under Mildly Acidic Conditions

Metal ions and their interaction with the amyloid beta (Aβ) peptide might be key elements in the development of Alzheimer's disease. In this work the effect of Cu^II on the aggregation of Aβ is explored on a timescale from milliseconds to days, both at physiological pH and under mildly acidic conditions, by using stopped‐flow kinetic measurements (fluorescence and light‐scattering), ¹H NMR relaxation and ThT fluorescence. A minimal reaction model that relates the initial Cu^II binding and Aβ folding with downstream aggregation is presented. We demonstrate that a highly aggregation prone Aβ ? Cu^II species is formed on the sub‐second timescale at mildly acidic pH. This observation might be central to the molecular origin of the known detrimental effect of acidosis in Alzheimer's disease.     

One Question,Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists

Fragment‐based lead discovery is gaining momentum in drug development. Typically, a hierarchical cascade of several screening techniques is consulted to identify fragment hits which are then analyzed by crystallography. Because crystal structures with bound fragments are essential for the subsequent hit‐to‐lead‐to‐drug optimization, the screening process should distinguish reliably between binders and non‐binders. We therefore investigated whether different screening methods would reveal similar collections of putative binders. First we used a biochemical assay to identify fragments that bind to endothiapepsin, a surrogate for disease‐relevant aspartic proteases. In a comprehensive screening approach, we then evaluated our 361‐entry library by using a reporter‐displacement assay, saturation‐transfer difference NMR, native mass spectrometry, thermophoresis, and a thermal shift assay. While the combined results of these screening methods retrieve 10 of the 11 crystal structures originally predicted by the biochemical assay, the mutual overlap of individual hit lists is surprisingly low, highlighting that each technique operates on different biophysical principles and conditions.     

Modification of Polycarbonate and Glycol Modified Poly(ethylene terephthalate) by Addition of Silica‐Nanoparticles Grafted with SAN Copolymer Using “Classical” and ARGET ATRP

This study presents a nanocomposite manufacturing route starting from non‐functionalized nanosilica and SAN surface modification via “grafting from” ATRP up to processing of transparent polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites. Synthesis limitations of low molecular weight graft SAN derived from “classical” ATRP are overcome by employment of the emerging ARGET ATRP. Mechanical investigations of polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites present up to 80% enhancement of creep performance and additionally 70% enhancement against wear abrasion for glycol modified poly(ethylene terephthalate) nanocomposites. Strength and tensile modulus are only moderately influenced by the addition of nanoparticles. Morphological studies confirm that the present modification route is able to create uniform dispersions of single particles and small particle aggregates in polymer matrices.

     

Calcium in Red Blood Cells—A Perilous Balance

Ca²⁺ is a universal signalling molecule involved in regulating cell cycle and fate, metabolism and structural integrity, motility and volume. Like other cells, red blood cells (RBCs) rely on Ca²⁺ dependent signalling during differentiation from precursor cells. Intracellular Ca²⁺ levels in the circulating human RBCs take part not only in controlling biophysical properties such as membrane composition, volume and rheological properties, but also physiological parameters such as metabolic activity, redox state and cell clearance. Extremely low basal permeability of the human RBC membrane to Ca²⁺ and a powerful Ca²⁺ pump maintains intracellular free Ca²⁺ levels between 30 and 60 nM, whereas blood plasma Ca²⁺ is approximately 1.8 mM. Thus, activation of Ca²⁺ uptake has an impressive impact on multiple processes in the cells rendering Ca²⁺ a master regulator in RBCs. Malfunction of Ca²⁺ transporters in human RBCs leads to excessive accumulation of Ca²⁺ within the cells. This is associated with a number of pathological states including sickle cell disease, thalassemia, phosphofructokinase deficiency and other forms of hereditary anaemia. Continuous progress in unravelling the molecular nature of Ca²⁺ transport pathways allows harnessing Ca²⁺ uptake, avoiding premature RBC clearance and thrombotic complications. This review summarizes our current knowledge of Ca²⁺ signalling in RBCs emphasizing the importance of this inorganic cation in RBC function and survival.