Features of assessing the condition and behavior of low-water bridges

The article describes features of operation and monitoring of low-water bridges, which are found on highways of regional, intermunicipal and local importance. Vibrations of the bridge span are considered in detail, taking into account its interaction with other structural elements and the environment. As a characteristic, the change of which takes into account the change in the state of the bridge structure, it is proposed to use the frequency of natural vibrations. To simulate the dynamic effects of transport and the dynamic behavior of individual elements and the entire structure as a whole, it is proposed to use viscoelastic elements of the Kelvin–Voigt type. When solving the problem, an approach has been implemented that makes it possible to take into account the anisotropic properties of the superstructure associated with various reinforcement along and across the roadway of the bridge, and to present the design scheme of the span not in the form of a beam supported at the edges with the help of hinges or viscoelastic dampers, but in the form of a plate, which can have different fxing conditions along the entire contour. The use of the proposed model and approach will make it possible to obtain the necessary data on the state of low-water bridges, for which there is often no possibility of visual inspection or instrumental inspection from the lower side of the bearing part of the superstructure. By the values of the frequency of natural vibrations, it is possible to estimate the water level above the low-water period and predict food situations, during which the roadway of the low-water bridge may be fooded.

Clogged water bridges for fog harvesting

Unless the fog particles are incident to the mesh-type fog harvesters with high inertia instead of circumventing the mesh domain, the clogged water bridges' effect on the fog-harvesting performance is not entirely negative.

Interactions between Beta-2-Glycoprotein-1 and Phospholipid Bilayer—A Molecular Dynamic Study

This study aims to investigate the interactions appearing when the beta-2-glycoprotein-1 binds to a lipid bilayer. The inter- and intra-molecular forces acting between the two macromolecular systems have been investigated using a molecular dynamics simulation method. The importance of water bridges has also been addressed. Additionally, the viscoelastic response of the bilayer has been studied. In detail, the (saturated-chain) 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and (unsaturated-chain) 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) bilayers have been chosen to test their behavior near the protein. Both of the lipids have a polar head but different chemical structures and are similar to the main phospholipids present in the synovial fluid. This study is meaningful for further explaining the worsening friction properties in articular cartilage, as the inactivation of phospholipid bilayers by beta-2-glycoprotein-1 is believed to be a cause of the destruction of cartilage in most rheumatic diseases and osteoarthritis. It was found that the protein binds stronger to the DPPC bilayer than to the POPE, but in both cases, it has the potential to change the local bilayer stability. Nevertheless, the binding forces are placed within a small area (only a few lipids contribute to the binding, creating many interactions). However, together, they are not stronger than the covalent bonds between C–O, thus, potentially, it is possible to push the lipids into the bilayer but detaching the lipids’ heads from the tail is not possible. Additionally, the protein causes water displacement from the vicinity of the bilayer, and this may be a contributor to the instability of the bilayer (disrupting the water bridges needed for the stabilization of the bilayer, especially in the case of DPPC where the heads are not so well stabilized by H–bonds as they are in POPE). Moreover, it was found that the diffusivity of lipids in the DPPC bilayer bound to the protein is significantly different from the diffusivity of the ones which are not in contact with the protein. The POPE bilayer is stiffer due to intramolecular interactions, which are stronger than in the DPPC; thus, the viscous to elastic effects in the POPE case are more significant than in the case of the DPPC. It is, therefore, harder to destabilize the POPE bilayer than the DPPC one.

Proton Conduction via Water Bridges Hydrated in the Collagen Film

Collagen films with proton conduction are a candidate of next generation of fuel-cell electrolyte. To clarify a relation between proton conductivity and formation of water networks in the collagen film originating from a tilapia’s scale, we systematically measured the ac conductivity, infrared absorption spectrum, and weight change as a function of relative humidity (RH) at room temperature. The integrated absorbance concerning an O–H stretching mode of water molecules increases above 60% RH in accordance with the weight change. The dc conductivity varies in the vicinity of 60 and 83% RH. From those results, we have determined the dc conductivity vs. hydration number (N) per unit (Gly-X-Y). The proton conduction is negligible in the collagen molecule itself, but dominated by the hydration shell, the development of which is characterized with three regions. For 0 < N < 2, the conductivity is extremely small, because the water molecule in the primary hydration shell has a little hydrogen bonded with each other. For 2 < N < 4, a quasi-one-dimensional proton conduction occurs through intra-water bridges in the helix. For 4 < N, the water molecule fills the helix, and inter-water bridges are formed in between the adjacent helices, so that a proton-conducting network is extended three dimensional.