On the Massive Antenna Suspension System in the Brazilian Gravitational Wave Detector SCHENBERG

SCHENBERG is a resonant-mass gravitational wave detector built in Brazil. Its spherical antenna, weighting 1.15 t, is connected to the outside world by a suspension system whose main function is to attenuate the external seismic noise. In this work, we report how the system was modeled using finite elements method. The model was validated on experimental data. The simulation showed that the attenuation obtained is of the order of 260 dB, which is sufficient for decreasing the seismic noise below the level of the thermal noise of the detector operating at 50 mK.     

Discrimination of Excited States of Acetylacetone through Theoretical Molecular-Frame Photoelectron Angular Distributions

Photoelectron angular distribution (PAD) in the laboratory frame for randomly oriented molecules is typically described by a single anisotropy parameter, the so-called asymmetry parameter. However, especially from a theoretical perspective, it is more natural to consider molecular photoionization by using a molecular frame. The molecular frame PADs (MFPADs) may be used to extract information about the electronic structure of the system studied. In the last decade, significant experimental efforts have been directed to MFPAD measurements. MFPADs are highly characterizing signatures of the final ionic states. In particular, they are very sensitive to the nature of the final state, which is embodied in the corresponding Dyson orbital. In our previous work on acetylacetone, a prototype system for studying intra-molecular hydrogen bond interactions, we followed the dynamics of the excited states involved in the photoexcitation–deexcitation process of this molecule. It remains to be explored the possibility of discriminating between different excited states through the MFPAD profiles. The calculation of MFPADs to differentiate excited states can pave the way to the possibility of a clear discrimination for all the cases where the recognition of excited states is otherwise intricate.     

Temperature and Composition Dependent Optical Properties of CdSe/CdS Dot/Rod-Based Aerogel Networks

Employing nanocrystals (NCs) as building blocks of porous aerogel network structures allows the conversion of NC materials into macroscopic solid structures while conserving their unique nanoscopic properties. Understanding the interplay of the network formation and its influence on these properties like size-dependent emission is a key to apply techniques for the fabrication of novel nanocrystal aerogels. In this work, CdSe/CdS dot/rod NCs possessing two different CdSe core sizes were synthesized and converted into porous aerogel network structures. Temperature-dependent steady-state and time-resolved photoluminescence measurements were performed to expand the understanding of the optical and electronic properties of these network structures generated from these two different building blocks and correlate their optical with the structural properties. These investigations reveal the influence of network formation and aerogel production on the network-forming nanocrystals. Based on the two investigated NC building blocks and their aerogel networks, mixed network structures with various ratios of the two building blocks were produced and likewise optically characterized. Since the different building blocks show diverse optical response, this technique presents a straightforward way to color-tune the resulting networks simply by choosing the building block ratio in connection with their quantum yield.     

Mycopyranone: A 8,8ˈ-binaphthopyranone with potent anti-MRSA activity from the fungus Phialemoniopsis sp.

A new 8,8?-binaphthopyranone (mycopyranone, 1) was isolated from a solid fermentation of Phialemoniopsis sp. (fungal strain MSX61662), and the structure was elucidated via analysis of the NMR and HRESIMS data. The axial chirality of 1 was determined to be M by ECD. The central chirality at C-4/C-4? was assigned through a modified Mosher’s method, while the absolute configuration at C-3/C-3? was deduced based on analysis of the ³J_H-3-H-4 values and NOESY correlations. Compound 1 was evaluated for its antimicrobial properties against Staphylococcus aureus SA1199 and a clinically relevant methicillin-resistant S. aureus strain (MRSA USA300 LAC strain AH1263). Compound 1 inhibited the growth of both strains in a concentration dependent manner with IC₅₀ values in the low μM range. Molecular docking indicated that compound 1 binds to the FtsZ (tubulin-like) protein in the same pocket as viriditoxin (2), suggesting that 1 targets bacterial cell division.     

p53‐Dependent and p53‐Independent Responses of Cells Challenged by Photosensitization

The p53 protein exerts fundamental roles in cell responses to a variety of stress stimuli. It has clear roles in controlling cell cycle, triggering apoptosis, activating autophagy and modulating DNA damage response. Little is known about the role of p53 in autophagy‐associated cell death, which can be induced by photoactivation of photosensitizers within cells. The photosensitizer 1,9‐dimethyl methylene blue (DMMB) within nanomolar concentration regimes has specific intracellular targets (mitochondria and lysosomes), photoinducing a typical scenario of cell death with autophagy. Importantly, in consequence of its subcellular localization, photoactive DMMB induces selective damage to mitochondrial DNA, saving nuclear DNA. By challenging cells having different p53 protein levels, we investigated whether p53 modulates DMMB/light‐induced phototoxicity and cell cycle dynamics. Cells lacking p53 activity were slightly more resistant to photoactivated DMMB, which was correlated with a smaller sub‐G1 population, indicative of a lower level of apoptosis. DMMB photosensitization seems to induce mostly autophagy‐associated cell death and S‐phase cell cycle arrest with replication stress. Remarkably, these responses were independent on the p53 status, indicating that p53 is not involved in either process. Despite describing some p53‐related responses in cells challenged by photosensitization, our results also provide novel information on the consequences of DMMB phototoxicity.     

Towards Photochromic Azobenzene-Based Inhibitors for Tryptophan Synthase

Light regulation of drug molecules has gained growing interest in biochemical and pharmacological research in recent years. In addition, a serious need for novel molecular targets of antibiotics has emerged presently. Herein, the development of a photocontrollable, azobenzene-based antibiotic precursor towards tryptophan synthase (TS), an essential metabolic multienzyme complex in bacteria, is presented. The compound exhibited moderately strong inhibition of TS in its E configuration and five times lower inhibition strength in its Z configuration. A combination of biochemical, crystallographic, and computational analyses was used to characterize the inhibition mode of this compound. Remarkably, binding of the inhibitor to a hitherto-unconsidered cavity results in an unproductive conformation of TS leading to noncompetitive inhibition of tryptophan production. In conclusion, we created a promising lead compound for combatting bacterial diseases, which targets an essential metabolic enzyme, and whose inhibition strength can be controlled with light.     

Examining the Potential of Plasma-Assisted Pretreated Wheat Straw for Enzyme Production by <Emphasis Type="Italic">Trichoderma reesei</Emphasis>

Plasma-assisted pretreated wheat straw was investigated for cellulase and xylanase production by Trichoderma reesei fermentation. Fermentations were conducted with media containing washed and unwashed plasma-assisted pretreated wheat straw as carbon source which was sterilized by autoclavation. To account for any effects of autoclavation, a comparison was made with unsterilized media containing antibiotics. It was found that unsterilized washed plasma-assisted pretreated wheat straw (which contained antibiotics) was best suited for the production of xylanases (110 IU ml⁻¹) and cellulases (0.5 filter paper units (FPU) ml⁻¹). Addition of Avicel boosted enzyme titers with the highest cellulase titers (1.5 FPU ml⁻¹) found with addition of 50 % w/w Avicel and with the highest xylanase production (350 IU ml⁻¹) reached in the presence of 10 % w/w Avicel. Comparison with enzyme titers from other nonrefined feedstocks suggests that plasma pretreated wheat straw is a promising and suitable substrate for cellulase and hemicellulase production.     

qNMR for profiling the production of fungal secondary metabolites

Analysis of complex mixtures is a common challenge in natural products research. Quantitative nuclear magnetic resonance spectroscopy offers analysis of complex mixtures at early stages and with benefits that are orthogonal to more common methods of quantitation, including ultraviolet absorption spectroscopy and mass spectrometry. Several experiments were conducted to construct a methodology for use in analysis of extracts of fungal cultures. A broadly applicable method was sought for analysis of both pure and complex samples through use of an externally calibrated method. This method has the benefit of not contaminating valuable samples with the calibrant, and it passed scrutiny for line fitting and reproducibility. The method was implemented to measure the yield of griseofulvin and dechlorogriseofulvin from three fungal isolates. An isolate of Xylaria cubensis (coded MSX48662) was found to biosynthesize griseofulvin in the greatest yield, 149 ± 8 mg per fermentation, and was selected for further supply experiments. Copyright © 2016 John Wiley & Sons, Ltd.