Hybrid analytical and numerical approach for modeling fluid flow in simplified three-dimensional fracture networks

<jats:p>Modeling fluid flow in three-dimensional fracture networks is required in a wide variety of applications related to fractured rocks. Numerical approaches developed for this purpose rely on either simplified representations of the physics of the considered problem using mesh-free methods at the fracture scale or complex meshing of the studied systems resulting in considerable computational costs. Here, we derive an alternative approach that does not rely on a full meshing of the fracture network yet maintains an accurate representation of the modeled physical processes. This is done by considering simplified fracture networks in which the fractures are represented as rectangles that are divided into rectangular subfractures such that the fracture intersections are defined on the borders of these subfractures. Two-dimensional analytical solutions for the Darcy-scale flow problem are utilized at the subfracture scale and coupled at the fracture-network scale through discretization nodes located on the subfracture borders. We investigate the impact of parameters related to the location and number of the discretization nodes on the results obtained, and we compare our results with those calculated using reference solutions, which are an analytical solution for simple configurations and a standard finite-element modeling approach for complex configurations. This work represents a first step towards the development of 3D hybrid analytical and numerical approaches where the impact of the surrounding matrix will be eventually considered.</jats:p&gt

Carboxylated photoswitchable diarylethenes for biolabeling and super-resolution RESOLFT microscopy.

Reversibly photoswitchable 1,2-bis(2-ethyl-6-phenyl-1-benzothiophene-1,1-dioxide-3-yl)perfluorocyclopentenes (EBT) having fluorescent "closed" forms were decorated with four or eight carboxylic groups and attached to antibodies. Low aggregation, efficient photoswitching in aqueous buffers, specific staining of cellular structures, and good photophysical properties were demonstrated. Alternating light pulses of UV and blue light induce numerous reversible photochemical transformations between two stables states with distinct structures. Using relatively low light intensities, EBTs were applied in biology-related super-resolution microscopy based on the reversible saturable (switchable) optical linear fluorescence transitions (RESOLFT) and demonstrated optical resolution of 75 nm

Carboxylierte photoschaltbare Diarylethene als Biomarkierungen für hochauflösende RESOLFT-Mikroskopie.

Reversibel photoschaltbares 1,2-Bis(2-ethyl-6-phenyl-1-benzothiophen-1,1-dioxid-3-yl)perfluorcyclopenten (EBT) mit fluoreszierender “geschlossener” Form wurde mit vier oder acht Carboxygruppen versehen und an Antikörper gebunden. Die carboxylierten Derivate wiesen geringe Aggregation, effizientes Photoschalten in wässrigen Puffern, gezieltes Färben von zellulären Strukturen und gute photophysikalische Eigenschaften auf. Abwechselnde Bestrahlung mit UV und blauem Licht relativ geringer Intensität führte zu reversibler photochemischer Isomerisierung zwischen zwei stabilen Strukturen über mehrere dutzend Schaltzyklen. Dies ermöglichte die Verwendung der Farbstoffe für hochauflösende RESOLFT-Mikroskopie (“reversible switchable optical linear fluorescence transitions”). Hierbei konnte eine optische Auflösung von 75 nm an zellulären Tubulin-Filamenten erzielt werden

Comparative genetic, proteomic and phosphoproteomic analysis of C. <i>elegans </i>embryos with a focus on <i>ham</i>-1/STOX and <i>pig</i>-1/MELK in dopaminergic neuron development

Asymmetric cell divisions are required for cellular diversity and defects can lead to altered daughter cell fates and numbers. In a genetic screen for C. elegans mutants with defects in dopaminergic head neuron specification or differentiation, we isolated a new allele of the transcription factor HAM-1 [HSN (Hermaphrodite-Specific Neurons) Abnormal Migration]. Loss of both HAM-1 and its target, the kinase PIG-1 [PAR-1(I)-like Gene], leads to abnormal dopaminergic head neuron numbers. We identified discrete genetic relationships between ham-1, pig-1 and apoptosis pathway genes in dopaminergic head neurons. We used an unbiased, quantitative mass spectrometry-based proteomics approach to characterise direct and indirect protein targets and pathways that mediate the effects of PIG-1 kinase loss in C. elegans embryos. Proteins showing changes in either abundance, or phosphorylation levels, between wild-type and pig-1 mutant embryos are predominantly connected with processes including cell cycle, asymmetric cell division, apoptosis and actomyosin-regulation. Several of these proteins play important roles in C. elegans development. Our data provide an in-depth characterisation of the C. elegans wild-type embryo proteome and phosphoproteome and can be explored via the Encyclopedia of Proteome Dynamics (EPD) - an open access, searchable online database

Coupling changes in cell shape to chromosome segregation

Animal cells undergo dramatic changes in shape, mechanics and polarity as they progress through the different stages of cell division. These changes begin at mitotic entry, with cell–substrate adhesion remodelling, assembly of a cortical actomyosin network and osmotic swelling, which together enable cells to adopt a near spherical form even when growing in a crowded tissue environment. These shape changes, which probably aid spindle assembly and positioning, are then reversed at mitotic exit to restore the interphase cell morphology. Here, we discuss the dynamics, regulation and function of these processes, and how cell shape changes and sister chromatid segregation are coupled to ensure that the daughter cells generated through division receive their fair inheritance

Live Imaging of a Hyperthermophilic Archaeon Reveals Distinct Roles for Two ESCRT-III Homologs in Ensuring a Robust and Symmetric Division.

Live-cell imaging has revolutionized our understanding of dynamic cellular processes in bacteria and eukaryotes. Although similar techniques have been applied to the study of halophilic archaea [1-5], our ability to explore the cell biology of thermophilic archaea has been limited by the technical challenges of imaging at high temperatures. Sulfolobus are the most intensively studied members of TACK archaea and have well-established molecular genetics [6-9]. Additionally, studies using Sulfolobus were among the first to reveal striking similarities between the cell biology of eukaryotes and archaea [10-15]. However, to date, it has not been possible to image Sulfolobus cells as they grow and divide. Here, we report the construction of the Sulfoscope, a heated chamber on an inverted fluorescent microscope that enables live-cell imaging of thermophiles. By using thermostable fluorescent probes together with this system, we were able to image Sulfolobus acidocaldarius cells live to reveal tight coupling between changes in DNA condensation, segregation, and cell division. Furthermore, by imaging deletion mutants, we observed functional differences between the two ESCRT-III proteins implicated in cytokinesis, CdvB1 and CdvB2. The deletion of cdvB1 compromised cell division, causing occasional division failures, whereas the ΔcdvB2 exhibited a profound loss of division symmetry, generating daughter cells that vary widely in size and eventually generating ghost cells. These data indicate that DNA separation and cytokinesis are coordinated in Sulfolobus, as is the case in eukaryotes, and that two contractile ESCRT-III polymers perform distinct roles to ensure that Sulfolobus cells undergo a robust and symmetrical division

Reference values for T, B and NK human lymphocyte subpopulations in adults

The data presented in this paper are reference ranges for frequencies of thirty-eight subpopulations of T, B and NK lymphocytes, established from a cohort of 253 healthy blood donors aged from 19 to 67. When relevant, the influence of age or sex was taken into account to calculate these reference values. This article is related to the research article entitled “Influence of age, sex and HCMV-serostatus on blood lymphocyte subpopulations in healthy adults” (Apoil et al., 2017) [1]. Immunophenotyping data obtained from each individual is made publicly available for extended analyses

Cloning of a rat gene encoding the histo-blood group B enzyme: rats have more than one Abo gene

A genomic DNA fragment corresponding to exon 7 of the human ABO gene was amplified from rats of several inbred and outbred strains. Five different sequences were obtained, four of them corresponding to A-type sequences and one to a B-type sequence based on the amino acids equivalent to residues at positions 266 and 268 of the human enzymes. In rats from inbred strains, a single A-type sequence and the unique B-type sequence were found, whereas some animals of outbred strains presented two or three A-type sequences along with the B-type sequence. The complete coding sequence of the B-type gene was obtained; identification of the exon-intron boundaries, determined by comparison with rat genomic sequences from data banks, revealed that the rat B-type gene structure is identical with that of the mouse Abo gene. Compared with the human ABO gene and the rat A gene, it lacks exon 4. Like the rat A gene (symbol: Abo), the rat B gene (symbol: Abo2) is located on chromosome 3q11-q12. It could be shown by transfection experiments that the B-type cDNA encodes an active B transferase. A transcript of the B gene was found ubiquitously, whereas the B antigen was only detected in a restricted set of tissues. These data indicate that rats have at least two distinct Abo genes, one monomorphic gene encoding a B-specific enzyme and one or more genes in some cases encoding an A-specific enzyme.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe