Quantum Dot Microdrop Laser Schäfer, J; Mondia, J. P; Sharma, R ...
2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science,
06/2008, Letnik:
8, Številka:
6
Journal Article, Conference Proceeding
Recenzirano
We report single-mode and multimode lasing from isolated spherical liquid microcavities containing CdSe/ZnS nanocrystal quantum dots. Lasing is observed at densities more than 2 orders of magnitude ...lower than previously demonstrated or theoretically predicted, assuming a uniform nanocrystal quantum dot distribution. Charged droplets, between 10 and 40 µm in size, are electrodynamically levitated and optically pumped. Substantial laser signals at low thresholds are measured from the directional emission normal to the pump beam, owing to the high Q cavity modes.
Functional groups that allow for chemoselective and bioorthogonal derivatization are valuable tools for the labelling of peptides and proteins. The isonitrile is such a group but synthetic methods ...for its incorporation into peptides by solid‐phase peptide synthesis are not known. Here, we introduce (4S)‐ and (4R)‐isonitrileproline (Inp) as building blocks for solid‐phase peptide synthesis. Conformational studies of (4S)‐ and (4R)‐Inp and thermal stability analysis of Inp‐containing collagen triple helices revealed that the isonitrile group exerts a stereoelectronic gauche effect. We showcase the value of Inp for bioorthogonal labelling by derivatization of Inp‐containing collagen model peptides (CMPs). Dual labelling with a pair of bioorthogonal reactions of a CMP containing Inp and azidoproline residues further highlights the versatility of the new isonitrile‐containing amino acids.
Isonitrileproline (Inp) is introduced as the first isonitrile‐containing amino acid for solid‐phase peptide synthesis. The conformation directing properties of the isonitrile group and its effect on the collagen triple helix were elucidated. The value of Inp for peptide derivatization was showcased by a chemoselective ligation with a functional chlorooxime.
This contribution focuses on understanding of paper wet-strength properties, by taking a closer look at the spatial distribution of wet-strengthening polymers inside the cellulosic fiber network ...deposited under different treatment conditions using confocal laser scanning microscopy as in situ imaging tool. We compare the behavior of paper samples treated with a photochemically cross-linkable copolymer using an impregnation process employing three different solvents, namely water, 2-propanol (IPA) and 1-butanol (BuOH), respectively. As these solvents swell paper fibers to quite different extents, the deposition of the polymer, on, in or in-between the cellulosic fibers varies quite strongly, as is shown by in-depth analysis using confocal laser scanning microscopy. The difference in accessibility of distinct surface sites exclusively on or also in and between the fibers controls the macroscopic tensile strength under both dry and wet conditions.
Terpene biosynthesis in marine sponge animals Wilson, Kayla; de Rond, Tristan; Burkhardt, Immo ...
Proceedings of the National Academy of Sciences - PNAS,
02/2023, Letnik:
120, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Sea sponges are the largest marine source of small-molecule natural products described to date. Sponge-derived molecules, such as the chemotherapeutic eribulin, the calcium-channel blocker manoalide, ...and antimalarial compound kalihinol A, are renowned for their impressive medicinal, chemical, and biological properties. Sponges contain microbiomes that control the production of many natural products isolated from these marine invertebrates. In fact, all genomic studies to date investigating the metabolic origins of sponge-derived small molecules concluded that microbes-not the sponge animal host-are the biosynthetic producers. However, early cell-sorting studies suggested the sponge animal host may play a role particularly in the production of terpenoid molecules. To investigate the genetic underpinnings of sponge terpenoid biosynthesis, we sequenced the metagenome and transcriptome of an isonitrile sesquiterpenoid-containing sponge of the order Bubarida. Using bioinformatic searches and biochemical validation, we identified a group of type I terpene synthases (TSs) from this sponge and multiple other species, the first of this enzyme class characterized from the sponge holobiome. The Bubarida TS-associated contigs consist of intron-containing genes homologous to sponge genes and feature GC percentage and coverage consistent with other eukaryotic sequences. We identified and characterized TS homologs from five different sponge species isolated from geographically distant locations, thereby suggesting a broad distribution amongst sponges. This work sheds light on the role of sponges in secondary metabolite production and speaks to the possibility that other sponge-specific molecules originate from the animal host.
Objective: Subjective social status (SSS) refers to individuals' perceived position in the social hierarchy. Prior research suggests that SSS relates to health above and beyond objective ...socioeconomic status (OSS) such as income, occupation, or education. Most findings in this field, however, stem from cross-sectional studies or longitudinal studies with one-time measurements of SSS only. The aim of this study was to examine reciprocal longitudinal associations of both national SSS (i.e., comparison with people in one's country) and local SSS (i.e., comparison with people in one's social environment) with health-related quality of life. Method: A two-wave cross-lagged panel design with a 2-year follow-up was used to analyze data for national SSS, local SSS, physical and mental health-related quality of life (PHQL and MHQL), as well as OSS from initially 2,156 individuals who participated in the German Socioeconomic Panel Study-Innovation Sample (SOEP-IS). Results: Local and national SSS at baseline predicted PHQL at follow up and partially mediated associations between OSS and PHQL. Local SSS (but not national SSS) also predicted MHQL at follow-up but this association was only marginally significant after inclusion of OSS in the model. Regarding a reverse health-to-SSS pathway, PHQL (but not MHQL) at baseline predicted local and national SSS at follow-up and these associations were partially mediated by income. Conclusion: This study extends cross-sectional observations by confirming that both local and national SSS have unique longitudinal associations with health and provides novel insights into longitudinal pathways linking SSS, OSS, and health.
The very first alkaline‐earth fluorooxoborate BaB4O6F2 was synthesised by solid state methods starting from Ba(BF4)2, β‐BaB2O4, and B2O3. The crystal structure derived from single‐crystal X‐ray ...diffraction (P21/n, a=6.6384(2) Å, b=7.6733(3) Å, c=11.3385(4) Å, β=91.281(2)°, Z=4, Rint=0.0269, R1=0.018, wR2=0.034) comprises layers of BO3F tetrahedra condensed through triangular BO3 units according to the descriptor 2Δ2□:<Δ2□>Δ. The extraordinary thirteen‐fold coordination of barium by oxygen and fluorine leads to interesting optical properties of a sample doped with divalent europium, where a 4f→4f emission was recorded around 359 nm together with a broad emission band of a 5d→4f emission peaking at 366 nm. The compound is further characterised by IR‐, Raman‐, and solid‐state NMR‐spectroscopic methods. Moreover, DFT calculations as well as TGA and DSC measurements were performed.
Weakly coordinating fluorooxoborates comprise BO3F tetrahedra condensed to triangular BO3 moieties, and are promising host structures for inorganic phosphors. Divalent europium on the barium site of this very first alkaline‐earth fluorooxoborate yielded an uncommon ultraviolet luminescence of broad‐band 5d→4f emission combined with narrow‐band 4f→4f emission of divalent europium.
Abstract
Aerosol levels influence the wavelength dependent transmission properties of the atmosphere. Variations in aerosol levels therefore affect the amount of Cherenkov light from air-showers that ...can reach an atmospheric Cherenkov detector. As the amount of detected Cherenkov light is directly related to a primary shower particle’s energy, deviations between actual and assumed atmospheric transmission properties yield errors in reconstructed particle energies as well as energy axes of instrument response functions. In this work, a scheme is presented to assess this influence and potentially reduce related errors in the air-shower reconstruction. The proposed scheme relies on estimations or measurements of the aerosol optical depth and atmospheric density profile which are then used in radiative transfer simulations to generate atmospheric transmission profiles. As the scheme furthermore uses detector specific quantum efficiencies and generalised shower evolution models, it does not rely on detailed Monte Carlo simulations for the different atmospheric conditions but only on the transmission profile which the initial shower reconstruction algorithm is based on. The approach is derived and presented on the example of the H.E.S.S. experiment which employs imaging atmospheric Cherenkov telescopes in the Khomas Highland of Namibia to detect gamma rays in the GeV to TeV energy range.
In the last years, applications for silver nanoparticles (Ag NPs) continue to increase together with the concerns about their potential input and hazards in aquatic ecosystems, where microalgae are ...key organisms. The aim of the present study was to assess the relative sensitivity of three marine microalgae species with differences in cell wall composition/structure exposed to Poly N-vinyl-2-pirrolidone/Polyethyleneimine (PVP/PEI) coated 5nm Ag NPs and uncoated 47nm Ag NP. As limited attention has been paid to the role of coating agents in NP toxicity, the effect of PVP/PEI alone was also evaluated. After 72h in artificial seawater, 47nm Ag NPs formed around 1400nm size aggregates while PVP/PEI coated 5nm Ag NPs reached around 90nm. Ag+ release in seawater was around 3% for 47nm Ag NPs and 30% for PVP/PEI coated 5nm Ag NPs. PVP/PEI coated 5nm Ag NP aggregates entrapped the algal cells in a network of heteroaggregates, while uncoated 47nm Ag NPs interacted to a lesser extent with algae. The concentration of PVP/PEI coated 5nm Ag NPs that exerted the median effect (EC50) on algae growth pointed out differences in algae sensitivity: T. suecica was about 10 times more sensitive than I. galbana and P. tricornutum. Further, the coating agent alone was as toxic to algae as PVP/PEI coated 5nm Ag NPs, suggesting that presence of the coating agent was the main driver of toxicity of coated NPs. Uncoated 47nm Ag NPs instead, showed similar toxicity towards algae although P. tricornutum was slightly less sensitive than T. suecica and I. galbana, which agrees with the presence of a resistant silicified cell wall in the diatom. The present work demonstrates differences in sensitivity of three marine microalgae, possibly related to their cell surface and size characteristics.
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•Effects of coated, uncoated Ag NPs and coating agent on microalgae were evaluated.•Coated 5 nm Ag NPs produced aggregates of smaller size and released 10 times more Ag ions than uncoated 47 nm Ag NPs.•Coated 5 nm Ag NPs were more toxic than uncoated 47 nm Ag NPs.•The coating agent alone was as toxic as coated 5 nm Ag NPs.•Tetraselmis suecica was about 10 times more sensitive than Isochrysis galbana and Phaeodactylum tricornutum.
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