Search results for "LIX"

<title>New PW stretcher-compressor design for PHELIX laser</title>

2005

With PHELIX (Petawatt High Energy Laser for heavy Ion EXperiments) a high energy/ultra-high intensity laser system is currently under construction at the GSI (Gesellschaft fur SchwerIonenforschung, Germany). In combination with the high current high energy ion accelerator facility this will provide worldwide unique experimental opportunities in the field of dense plasma physics and inertial fusion research. In the long pulse mode the laser system will provide laser pulses of up to 5 kJ in 1-10 ns pulses. In the high intensity mode pulse powers in excess of 1 PW will be achieved. For this the well known technique of chirped pulse amplification (CPA) will be implemented. A new CPA stretcher-c…

Crystal structure of t-Butylcalix[8]arene octamethyl ether

2002

Abstract The title compound 1a crystallized with a molecule of chloroform in a triclinic lattice, space group P-1, with a=16.5215(19) A, b=17.4181(19) A, c=18.7403(18) A, α=78.328(8)°, β=64.210(8)°, γ=87.863(9)°, Z=2. The molecule assumes a not yet observed conformation with approximate (not crystallographic) C4V-symmetry with the inclusion of one molecule of chloroform in the molecular cavity. Layers of molecules are packed in alternating order in the crystal lattice.

The Folding State of the Lumenal Loop Determines the Thermal Stability of Light-Harvesting Chlorophyll a/b Protein

2004

The major light-harvesting protein of photosystem II (LHCIIb) is the most abundant chlorophyll-binding protein in the thylakoid membrane. It contains three membrane-spanning alpha helices; the first and third one closely interact with each other to form a super helix, and all three helices bind most of the pigment cofactors. The protein loop domains connecting the alpha helices also play an important role in stabilizing the LHCIIb structure. Single amino acid exchanges in either loop were found to be sufficient to significantly destabilize the complex assembled in vitro [Heinemann, B., and Paulsen, H. (1999) Biochemistry 38, 14088-14093. Mick, V., Eggert, K., Heinemann, B., Geister, S., and…

Chromatin remodelling factor Mll1 is essential for neurogenesis from postnatal neural stem cells

2009

Epigenetic mechanisms that maintain neurogenesis throughout adult life remain poorly understood(1). Trithorax group (trxG) and Polycomb group (PcG) gene products are part of an evolutionarily conserved chromatin remodelling system that activate or silence gene expression, respectively(2). Although PcG member Bmi1 has been shown to be required for postnatal neural stem cell self-renewal(3,4), the role of trxG genes remains unknown. Here we show that the trxG member Mll1 (mixed-lineage leukaemia 1) is required for neurogenesis in the mouse postnatal brain. Mll1-deficient subventricular zone neural stem cells survive, proliferate and efficiently differentiate into glial lineages; however, neur…

Ciclo riproduttivo di Arbacia lixula (Linneo, 1758) (Echinodermata: echinoidea) nella AMP “Isola di Ustica”

2009

A Classical Synthesis of the Collagen-like Peptides with the Sequence Z(GlyProPro)nOBut and their characterization with circular dichroism and ultrac…

1975

Oligopeptides with the sequence Z(GlyProPro)nOBut (n = 3–7) were synthesized along a clasical pathway. Generally long fragments were condensed in order to allow an easy separation of the products from the reactants. It is established by molecular weight determination and measurements of circular dichroism that the peptides form the collagen-like triple helix in methanol and that they assume the random coil conformation in dilute acetic acid. The circular dichroism spectra agree reasonably well with the corresponding spectra for (ProProGly)10 which was obtained by solid phase synthesis in another laboratory.

Azacoccones F-H, new flavipin-derived alkaloids from an endophytic fungus Epicoccum nigrum MK214079.

2020

Abstract Three new flavipin-derived alkaloids, azacoccones F-H (1–3), along with six known compounds (4–9) were isolated from the endophytic fungus Epicoccum nigrum MK214079 associated with leaves of Salix sp. The structures of the new compounds were established by analysis of their 1D/2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS) data. The absolute configuration of azacoccones F-H (1–3) was determined by comparison of experimental electronic circular dichroism (ECD) data with reported ones and biogenetic considerations. Epicocconigrone A (4), epipyrone A (5), and epicoccolide B (6) exhibited moderate antibacterial activity again…

Corrosion of Heritage Objects: Collagen‐Like Triple Helix Found in the Calcium Acetate Hemihydrate Crystal Structure

2020

Abstract Helical motifs are common in nature, for example, the DNA double or the collagen triple helix. In the latter proteins, the helical motif originates from glycine, the smallest amino acid, whose molecular confirmation is closely related to acetic acid. The combination of acetic acid with calcium and water, which are also omnipresent in nature, materializing as calcium acetate hemihydrate, was now revealed to exhibit a collagen‐like triple helix structure. This calcium salt is observed as efflorescence phase on calcareous heritage objects, like historic Mollusca shells, pottery or marble reliefs. In a model experiment pure calcium acetate hemihydrate was crystallized on the surface of…

Consequences of food-attraction conditioning in Helix: a behavioral and electrophysiological study

1996

Food-attraction conditioning is a learning phenomenon by which adult Helix pomatia acquire the ability to locate food through exposure to that particular food. Food-conditioned snails can be distinguished from ‘naive’ snails during their approach to food. ‘Naive’ snails keep their tentacles upright — whereas ‘food-conditioned’ animals bend the tentacles down-ward, in a horizontal orientation, pointed in the direction of the food.

Citocentrifugación como un método adicional para estudiar celomitos de equinodermos: un enfoque comparativo que combina células vivas, preparaciones …

2021

Abstract Introduction: Echinoderm coelomocytes have traditionally been investigated through a morphological approach using light microscopy, which relies on the idea of constant cell shape as a stable character. However, this can be affected by biotic or abiotic conditions. Objective: To analyze if the consistency in cell morphology offered by the cytocentrifugation method, might be used as a convenient tool to study echinoderm coelomocytes. Methods: Cells of Echinaster (Othilia) brasiliensis (Asteroidea), Holothuria (Holothuria) tubulosa (Holothuroidea), Eucidaris tribuloides, Arbacia lixula, Lytechinus variegatus, and Echinometra lucunter (Echinoidea) were spread on microscope slides by c…