Search results for "Microscopy"

Preparation of Thin-Film Frozen-Hydrated/ Vitrified Biological Specimens for Cryoelectron Microscopy

2003

Organic fractal nano-dimensional structures based on fullerene C60

2019

The ways for a synthesis of nanoporous and close-packed types of fullerene C60 aggregates in two-component organic solvents (toluene + tetrahydrofuran) were established as well as their structural ...

Substrate templating guides the photoinduced reaction of C60on calcite

2014

cited By 7; International audience; A substrate-guided photochemical reaction of C60 fullerenes on calcite, a bulk insulator, investigated by non-contact atomic force microscopy is presented. The success of the covalent linkage is evident from a shortening of the intermolecular distances, which is clearly expressed by the disappearance of the moiré pattern. Furthermore, UV/Vis spectroscopy and mass spectrometry measurements carried out on thick films demonstrate the ability of our setup for initiating the photoinduced reaction. The irradiation of C60 results in well-oriented covalently linked domains. The orientation of these domains is dictated by the lattice dimensions of the underlying c…

Colonization of tomato root by pathogenic and nonpathogenic Fusarium oxysporum strains inoculated together and separately into the soil.

2006

ABSTRACT In soil, fungal colonization of plant roots has been traditionally studied by indirect methods such as microbial isolation that do not enable direct observation of infection sites or of interactions between fungal pathogens and their antagonists. Confocal laser scanning microscopy was used to visualize the colonization of tomato roots in heat-treated soil and to observe the interactions between a nonpathogenic strain, Fo47, and a pathogenic strain, Fol8, inoculated onto tomato roots in soil. When inoculated separately, both fungi colonized the entire root surface, with the exception of the apical zone. When both strains were introduced together, they both colonized the root surface…

Bio-sintering processes in hexactinellid sponges: Fusion of bio-silica in giant basal spicules from Monorhaphis chuni☆

2009

The two sponge classes, Hexactinellida and Demospongiae, comprise a skeleton that is composed of siliceous skeletal elements (spicules). Spicule growth proceeds by appositional layering of lamellae that consist of silica nanoparticles, which are synthesized via the sponge-specific enzyme silicatein. While in demosponges during maturation the lamellae consolidate to a solid rod, the lamellar organization of hexactinellid spicules largely persists. However, the innermost lamellae, near the spicule core, can also fuse to a solid axial cylinder. Similar to the fusion of siliceous nanoparticles and lamella, in several hexactinellid species individual spicules unify during sintering-like processe…

Polish is quantitatively different on quartzite flakes used on different worked materials.

2020

Metrology has been successfully used in the last decade to quantify use-wear on stone tools. Such techniques have been mostly applied to fine-grained rocks (chert), while studies on coarse-grained raw materials have been relatively infrequent. In this study, confocal microscopy was employed to investigate polished surfaces on a coarse-grained lithology, quartzite. Wear originating from contact with five different worked materials were classified in a data-driven approach using machine learning. Two different classifiers, a decision tree and a support-vector machine, were used to assign the different textures to a worked material based on a selected number of parameters (Mean density of furr…

Binding and/or hydrolysis of purine‐based nucleotides is not required for IM30 ring formation

2021

IM30, the inner membrane-associated protein of 30 kDa, is conserved in cyanobacteria and chloroplasts. Although its exact physiological function is still mysterious, IM30 is clearly essential for thylakoid membrane biogenesis and/or dynamics. Recently, a cryptic IM30 GTPase activity has been reported, albeit thus far no physiological function has been attributed to this. Yet, it is still possible that GTP binding/hydrolysis affects formation of the prototypical large homo-oligomeric IM30 ring and rod structures. Here, we show that the Synechocystis sp. PCC 6803 IM30 protein in fact is an NTPase that hydrolyzes GTP and ATP, but not CTP or UTP, with about identical rates. While IM30 forms lar…

Impact of gadolinium on the structure and magnetic properties of nanocrystalline powders of iron oxides produced by the extraction-pyrolytic method

2020

The work has been done in frame of the TransFerr project. It has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 778070. This research was also supported by Latvian Research Council project lzp-2018/1-0214. A.I.P. appreciates support from the Estonian Research Council grant (PUT PRG619).

Role of Human Sec63 in Modulating the Steady-State Levels of Multi-Spanning Membrane Proteins

2012

The Sec61 translocon of the endoplasmic reticulum (ER) membrane forms an aqueous pore, allowing polypeptides to be transferred across or integrated into membranes. Protein translocation into the ER can occur co- and posttranslationally. In yeast, posttranslational translocation involves the heptameric translocase complex including its Sec62p and Sec63p subunits. The mammalian ER membrane contains orthologs of yeast Sec62p and Sec63p, but their function is poorly understood. Here, we analyzed the effects of excess and deficit Sec63 on various ER cargoes using human cell culture systems. The overexpression of Sec63 reduces the steady-state levels of viral and cellular multi-spanning membrane …

Size characterisation of Au nanoparticles by ICP-MS coupling techniques

2006

In modern nanotechnology the properties of nanoparticles (NPs) in different application fields is mainly dependent on their size and their size distribution. This paper aims to develop a reliable method for the size characterisation of Au NPs. Basing on the combination of two different separation techniques (liquid chromatography and gel electrophoresis), coupled on-line to inductively coupled plasma-mass spectrometry (ICP-MS), we study the separation of Au NP standards. Separations by liquid chromatography show size dependent retention behaviour with good reproducibility (RSD < 1%). The results are compared with complementary methods like dynamic light scattering (DLS) and transmission ele…