Description: A recent empirical study of Stanhill et al. [2014], which was based on the Angstrom-Prescott relationship between global radiation and sunshine duration, was evaluated. The parameters of this relationship seemed to be rather stable across the dimming and brightening periods. Thus, the authors concluded that the variation in global radiation is more influenced by changes in cloud cover and sunshine duration than by the direct aerosol effects. In our study, done for the Potsdam station (one of six globally distributed stations, the source of one of the longest observational records and closely located to former hotspots of aerosol emission), we tested and rejected the hypothesis that the dimming of global radiation directly caused by aerosols is negligible. The residuals of the Angstrom-Prescott regression reveal a statistically significant positive temporal trend and a temporal level segmentation. The latter was consistent with the temporal emission patterns around Potsdam. The trend in the residuals only disappeared when the model intercept varied according to the temporal level segmentation. The magnitude of the direct aerosol effect on the level changes in global radiation derived from the modified Angstrom-Prescott relationship was in the range indicated in previous studies. Thus from here, a specific request cannot be made for a revision of current climate models state-of-the-art representation of both the cooling effect directly caused by aerosols and the temperature sensitivity to the increase of greenhouse gases.

Description: Providing enantiomerically pure products is of key importance in the fine chemicals, food, and pharmaceutical industries. A continuous preferential crystallization process is presented that allows the separation of conglomerate forming enantiomers in a stable, robust, and flexible way. This is achieved by coupling two continuous crystallizers by exchanging their clear liquid phases. Each crystallizer is connected to a suspension mill responsible for in situ seed generation through particle breakage. The dynamic and steady-state behavior of this process is extensively analyzed for racemic feed streams through process simulations, and parameter regions, which yield pure enantiomers in both crystallizers, are identified. For enriched feed streams, it is further shown when this novel flow sheet is capable of outperforming an ideal batch process in terms of solvent consumption per unit mass of desired enantiopure product produced. © 2015 American Institute of Chemical Engineers AIChE J , 61: 2810–2823, 2015

Description: We report on the properties of radially self-accelerating intensity distributions consisting of two components in the angular frequency domain. We show how this subset of solutions, in literature also known as helicon beams, possesses peculiar characteristics that enable a better control over its properties. In this work, we present a step-by-step optimization procedure to achieve the best possible intensity contrast, a distinct rotation rate and long propagation lengths. All points are discussed on a theoretical basis and are experimentally verified.

Description: In intestinal and pyloric epithelia leucine-rich repeat-containing G protein-coupled receptor 5 ( Lgr5 )-expressing cells represent long-lived adult stem cells which give rise to all epithelial cell types including endocrine cells. Ablation of the Apc gene in Lgr5 -expressing cells leads to intestinal and pyloric adenomas. To assess whether all epithelial tumours of the gastrointestinal tract are derived from LGR5-positive stem cells we crossed Lgr5-EGFP-IRES-creER T2 mice which express EGFP and Cre recombinase driven by the Lgr5 promoter with CEA424-SV40-TAg mice which develop pyloric neuroendocrine carcinomas of epithelial origin. In 19-day-old mice, single SV40 T antigen (TAg)-positive cells were identified preferentially at the the base of pyloric glands close to the stem cell compartment. However, contrary to previous publications describing subpopulations of LGR5-positive cells in gastrointestinal neoplasia we could not detect Lgr5- EGFP-positive tumour cells in malignant lesions. The lack of expression of the Wnt target gene Lgr5 is probably not caused by suppression of Wnt signalling by TAg since β-catenin-mediated Wnt signalling, as measured by the TOPflash assay, was not inhibited. To determine the cellular origin of CEA424-SV40-TAg tumours we performed tracing experiments using Lgr5-EGFP-IRES-creERT2:CEA424-SV40-TAg:ROSA26-tdRFP mice. Following tamoxifen induction it was possible to efficiently trace the progeny of Lgr5 -expressing cells in gastrointestinal tissue via red fluorescent protein (RFP) expression. No RFP-positive tumour cells were detected even when RFP gene activation occurred in 7-day-old mice well before the appearance of TAg-positive tumour cells. Hence we conclude that Lgr5 -expressing stem cells probably do not constitute the cells-of-origin in CEA424-SV40-TAg mice. Consequently, not all epithelial tumours in the pyloric region are initiated by transformation of LGR5-positive stem cells. Thus additional long-lived LGR5-negative stem cells or progenitor cells with low turnover rate might exist in the pyloric region which can give rise to tumours.

Description: Zooplankton from clear alpine lakes is exposed to stressful levels of solar UV radiation (UVR). As these pelagic organisms experience high UVR and large changes in solar radiation conditions between ice-free and ice-cover periods, they have evolved various strategies to minimize UVR exposure and damage. Here, we studied the relation between photoprotection levels (mycosporine-like amino acids, carotenoids), antioxidant capacities, and gene expression of heat shock proteins ( hsps ) as indicator of stress in the copepod Cyclops abyssorum tatricus during the course of a year. Expression of hsp60 , hsp70 , and hsp90 was measured in the field (baseline expression [BE]) and after UVR exposure in the laboratory. The BE differed among genes and seasons ( hsp60 : high during summer, hsp70 and hsp90 : high during the ice-cover period). The gene expression of hsp70 was upregulated after exposure to UVR (up to 5.2-fold change), while hsp60 and hsp90 were only constitutively expressed. A strong seasonal pattern was found in the photoprotective compounds and antioxidant capacities, with highest levels during the ice-free period. The extent of upregulation of hsp70 gene expression increased with decreasing photoprotection levels and peaked 24 h post UVR exposure (9.6-fold change) at the time of lowest photoprotection (February). Our data suggest that hsp70 gene expression is modulated by seasonal plasticity in photoprotection. This ability of adequate stress response is essential for survival in highly variable ecosystems such as alpine lakes.

Description: Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.

Description: Vibrio harveyi β- N -acetylglucosaminidase ( Vh GlcNAcase) is a new member of the GH20 glycoside hydrolase family responsible for the complete degradation of chitin fragments, with N -acetylglucosamine (GlcNAc) monomers as the final products. In this study, the crystallization and preliminary crystallographic data of wild-type Vh GlcNAcase and its catalytically inactive mutant D437A in the absence and the presence of substrate are reported. Crystals of wild-type Vh GlcNAcase were grown in 0.1  M sodium acetate pH 4.6, 1.4  M sodium malonate, while crystals of the D437A mutant were obtained in 0.1  M bis-tris pH 7.5, 0.1  M sodium acetate, 20% PEG 3350. X-ray data from the wild-type and the mutant crystals were collected at a synchrotron-radiation light source and were complete to a resolution of 2.5 Å. All crystals were composed of the same type of dimer, with the substrate N , N ′-diacetylglucosamine (GlcNAc 2 or diNAG) used for soaking was cleaved by the active enzyme, leaving only a single GlcNAc molecule bound to the protein.

Description: The spindle-assembly checkpoint (SAC) monitors kinetochore–microtubule attachment during mitosis. In metazoans, the three-subunit Rod–Zwilch–ZW10 (RZZ) complex is a crucial SAC component that interacts with additional SAC-activating and SAC-silencing components, including the Mad1–Mad2 complex and cytoplasmic dynein. The RZZ complex contains two copies of each subunit and has a predicted molecular mass of ∼800 kDa. Given the low abundance of the RZZ complex in natural sources, its recombinant reconstitution was attempted by co-expression of its subunits in insect cells. The RZZ complex was purified to homogeneity and subjected to systematic crystallization attempts. Initial crystals containing the entire RZZ complex were obtained using the sitting-drop method and were subjected to optimization to improve the diffraction resolution limit. The crystals belonged to space group P 3 1 (No. 144) or P 3 2 (No. 145), with unit-cell parameters a = b = 215.45, c = 458.7 Å, α = β = 90.0, γ = 120.0°.

Description: S100B is a damage-associated molecular pattern protein that, when released into the extracellular milieu, triggers initiation of the inflammatory response through the receptor for advanced glycation end products (RAGE). Recognition of S100B is accomplished via the amino-terminal variable immunoglobulin domain (V-domain) of RAGE. To gain insights into this interaction, a complex between S100B and a 15-amino-acid peptide derived from residues 54–68 of the V-domain was crystallized. The X-ray crystal structure was solved to 2.55 Å resolution. There are two dimers of S100B and one peptide in the asymmetric unit. The binding interface of this peptide is compared with that found in the complex between S100B and the 12-amino-acid CapZ-derived peptide TRTK-12. This comparison reveals that although the peptides adopt completely different backbone structures, the residues buried at the interface interact with S100B in similar regions to form stable complexes. The binding affinities of S100B for the intact wild-type V-domain and a W61A V-domain mutant were determined to be 2.7 ± 0.5 and 1.3 ± 0.7 µ M , respectively, using fluorescence titration experiments. These observations lead to a model whereby conformational flexibility in the RAGE receptor allows the adoption of a binding conformation for interaction with the stable hydrophobic groove on the surface of S100B.

Description: Fjords are disproportionately important for global organic carbon (OC) burial relative to their spatial extent, and may be important in sequestering atmospheric CO2, providing a negative climate feedback. Within fjords, multiple locally variable delivery mechanisms control mineral sediment deposition, which in turn modulates OC burial. Sediment and OC sources in Fiordland, New Zealand include terrigenous input at fjord heads, sediment reworking over fjord-mouth sills, and landslide events from steep fjord walls. Box cores were analyzed for sedimentary texture, sediment accumulation rate, and OC content to evaluate the relative importance of each delivery mechanism. Sediment accumulation was up to 3.4 mm/yr in proximal and distal fjord areas, with lower rates in medial reaches. X-radiograph and 210Pb stratigraphy indicate mass wasting and surface-sediment bioturbation throughout the fjords. Sediment accumulation rates are inversely correlated with %OC. Spatial heterogeneity in sediment depositional processes and rates is important when evaluating OC burial within fjords.