Properties of coatings based on carbon and nitrogen-doped carbon obtained using a pulsed vacuum arc method

Diamond-like carbon coatings on hard-alloy substrates, including coatings doped with nitrogen about 1.0 μm thick have been obtained using a pulse vacuum-arc method. Three types of coatings have been investigated: a carbon diamond-like coating (C), a carbon coating doped with nitrogen (C : N), and a composite coating based on (C : N + C) layer

The primary cilium as a dual sensor of mechanochemical signals in chondrocytes

The primary cilium is an immotile, solitary, and microtubule-based structure that projects from cell surfaces into the extracellular environment. The primary cilium functions as a dual sensor, as mechanosensors and chemosensors. The primary cilia coordinate several essential cell signaling pathways that are mainly involved in cell division and differentiation. A primary cilium malfunction can result in several human diseases. Mechanical loading is sense by mechanosensitive cells in nearly all tissues and organs. With this sensation, the mechanical signal is further transduced into biochemical signals involving pathways such as Akt, PKA, FAK, ERK, and MAPK. In this review, we focus on the fundamental functional and structural features of primary cilia in chondrocytes and chondrogenic cells

On complex-valued 2D eikonals. Part four: continuation past a caustic

Theories of monochromatic high-frequency electromagnetic fields have been designed by Felsen, Kravtsov, Ludwig and others with a view to portraying features that are ignored by geometrical optics. These theories have recourse to eikonals that encode information on both phase and amplitude -- in other words, are complex-valued. The following mathematical principle is ultimately behind the scenes: any geometric optical eikonal, which conventional rays engender in some light region, can be consistently continued in the shadow region beyond the relevant caustic, provided an alternative eikonal, endowed with a non-zero imaginary part, comes on stage. In the present paper we explore such a principle in dimension $2.$ We investigate a partial differential system that governs the real and the imaginary parts of complex-valued two-dimensional eikonals, and an initial value problem germane to it. In physical terms, the problem in hand amounts to detecting waves that rise beside, but on the dark side of, a given caustic. In mathematical terms, such a problem shows two main peculiarities: on the one hand, degeneracy near the initial curve; on the other hand, ill-posedness in the sense of Hadamard. We benefit from using a number of technical devices: hodograph transforms, artificial viscosity, and a suitable discretization. Approximate differentiation and a parody of the quasi-reversibility method are also involved. We offer an algorithm that restrains instability and produces effective approximate solutions.Comment: 48 pages, 15 figure

Lake Water Depth Controlling Archaeal Tetraether Distributions in Midlatitude Asia:Implications for Paleo Lake-Level. Reconstruction

Lake-level reconstructions, related to terrestrial hydrological changes, are important for our understanding of past and future climates. Currently, however, reliable lake-level proxies are still limited. Here we report distributions of archaeal tetraether lipids in 70 surface sediment samples collected from 55 lakes in midlatitude Asia. We have found that among various lake physico-chemical characteristics, the relative abundances of crenarchaeol and Hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers (%cren and %OH-GDGTs) are best correlated with lake water depth, due to a preference of Thaumarchaeota, the producer of these biomarkers, for a niche in subsurface lake water. This supports the recent hypothesis based on single-lake investigations that %cren and %OH-GDGTs are potentially novel lake-level proxies. Our results also suggest that %OH-GDGTs is less affected by soil input than %cren. Nevertheless, other confounding factors should be well constrained and local/site-specific calibrations are needed before the two molecular proxies are used quantitatively in down-core applications. Plain Language Summary Lake-level reconstructions can provide useful information about past changes in hydroclimate, which impact both ecosystems and socio-economic sustainable development in fundamental ways, but reliable lake-level proxies are still limited to date. Here we show that the %cren and %OH-GDGTs indices, calculated based on the distributions of archaeal membrane lipids, are controlled by lake water depth in lake surface sediments across a variety of lake conditions. This suggests that past lake level changes can be inferred by analyzing the ubiquitous archaeal lipids preserved in downcore lake sediments