Different Layers Of Structure Research Articles

Benzene Adsorption on Nanoporous Silica Gels with Grafted Polyfluoroalkyl Layers and the Wettability

Features of the benzene adsorption in polyfluoroalkyl layers of different structures grafted on surfaces of silica gel (SG) are studied using gas chromatography, static adsorption, and diffuse reflectance IR spectroscopy. After modification, Henry’s law constants determined from the gas chromatography data and the static benzene adsorption values fall in the order SG > SG–F(III) > SG–F > SG–iso-F(III), where samples SG–F(III), SG–F, and SG–iso-F(III) are produced using silanes n‑C6F13(CH2)2SiCl3, n‑C6F13(CH2)2Si(CH3)2Cl, and iso-C3F7(CH2)2SiCl3, respectively. It is found that the energy characteristics of adsorption of benzene and other hydrocarbons on the SG–F(III) sample with the linear trifunctional modifier are 3–7 kJ/mol higher than the respective characteristics determined on the initial support. The contact angles for nanoporous silica gels with polyfluoroalkyl layers are calculated from desorption data in the region of the capillary condensation hysteresis of the benzene adsorption isotherms.

Электрический разряд как технологический фактор интенсификации процессов химико-термической обработки изделий машиностроения

The advantages of nitriding in an electrostatic and high-frequency field connected with the possibility of carrying out processes at normal pressure are shown. The acceleration of the process of diffusion saturation with nitrogen in an electric field with the formation of a spark discharge as compared with gas nitriding is confirmed experimentally. This method of steel nitriding allows forming layers of different structure and thickness with the specified gradient of hardness.

Oxidation of Sintered VТ1-0 Titanium

We compare the results of oxidation of sintered powder titanium and deformed VT1-0 titanium. The differences between the formation of diffusion and oxide layers are detected by the X-ray diffraction, X-ray phase diffraction, durometric, and metallographic investigations. The protective properties of oxide layers of different structures are evaluated according to the results of corrosion tests in a 20% solution of hydrochloric acid.

Internal structure of Daphnia ephippium as an adaptation to dispersion

We compared the internal structure and considered the potential functions of the ephippial walls of several species of Daphniidae. We found that the walls of ephippia in Daphniidae are composed of three interconnected layers of different structure. The external and internal layers, which are relatively solid, are covered by cell-like multiple polyhedron compartments formed by the middle layer. The three layers, which resemble a honeycomb structure, may offer mechanical protection for dormant eggs on one hand and may facilitate passive dispersal of ephippia containing diapausing eggs on the other. The cell-like compartments within the wall may be filled with air that makes them buoyant and may facilitate their passive dispersal within or between water bodies by animate or inanimate vectors operating on the water surface. We found significant structural differences between the ephippia of representatives from the subgenus Daphnia vs Ctenodaphnia. In the first group (in Daphnia pulex and Daphnia longispina) the middle layer is formed from empty cells readily filled with air even after brief contact with the atmosphere while in Ctenodaphnia such as Daphnia magna and Daphnia lumholtzi the middle layer of the ephippium cells are filled with filaments which hardly absorb atmospheric air. Structural differences between the two groups may reflect both their phylogenetic divergence and their various dispersal strategies.

3D engineered neuronal networks coupled to 3D-MEAs: a new experimental model for in-vitro electrophysiology

3D engineered neuronal networks coupled to 3D-MEAs: a new experimental model for in-vitro electrophysiology

Fabrication of triple-layered vascular scaffolds by combining electrospinning, braiding, and thermally induced phase separation

Triple-layered small diameter vascular scaffolds, which consisted of thermoplastic polyurethane (TPU) and silk, were fabricated in this study for the first time by combining electrospinning, braiding, and thermally induced phase separation methods. These novel vascular scaffolds, which possess three layers of different structures (nanofibrous inner layer, woven silk filament middle layer, and porous outer layer), can mimic the structure of native blood vessels. The vascular scaffolds have a desirable toe region in tensile tests and sufficient suture retention and burst pressure for vascular graft applications. Endothelial cell culture tests showed that a cell layer could form on the inner surface of the scaffold with high cell viability and favorable morphology.

Heat treatment of Fe–V–W–Mo–Cr alloy roll collar

Compound roll collars having inner and outer layers of different structure and hardness were obtained by controlling the cooling rate of the inner layer during heat treatment of the centrifugal cast structure by applying an insulating coating. A neural network was employed to determine the effect of heat treatment variables on the hardness distribution obtained in the collar. The neural network model was found to predict appropriate process parameters for heat treatment.

Synthesis and Performance of PP Microfiltration Membranes Grafted with Polymer Layers of Different Structure

Reproducible and controllable hydrophilic layers were grafted on macroporous PP membranes by surface initiated grafting. Two methods were adopted, i.e., through adsorption of or entrapping the photo-initiator on the membrane surface. The latter method yielded longer grafted chains under otherwise identical conditions. Depending on monomer solution composition, brush layers or network-like structures were grafted onto the entire membrane surface without significant loss of water flux. The influence of the structure of grafted layers on water permeation, protein adsorption, and protein microfiltration fluxes was investigated. It was found that membranes grafted with network-like structures have the best performance.

PhaP Is Involved in the Formation of a Network on the Surface of Polyhydroxyalkanoate Inclusions in Cupriavidus necator H16

Polyhydroxyalkanoate (PHA) inclusions are polymeric storage inclusions formed in some bacterial species when carbon levels are high but levels of another essential nutrient, such as nitrogen, are low. Though much is known about PHA synthesis, little is known about inclusion structure. In this study, atomic force microscopy (AFM) was employed to elucidate the structure of PHA inclusions at the nanoscale level, including the characterization of different layers of structure. AFM data suggest that underneath the inclusion envelope, there is a 2- to 4-nm-thick network layer that resides on top of a harder layer that is likely to be a crystalline lamellar polymer. The network is comprised of approximately 20-nm-wide linear segments and junctions that are typically formed by the joining of three to four of the linear segments. In some cases, approximately 50-nm globular structures that are raised approximately 1 to 2 nm above the network are present at the junctions. These globular structures always have a central pore that is approximately 15 nm in diameter. To determine if the major surface protein of PHA inclusions, PhaP, is involved in the structure of this network, inclusions from Cupriavidus necator H16 DeltaphaP were examined. No network structure was detected. Instead, apparently random globular structures were found on the surfaces of the inclusions. When PhaP levels were reconstituted in this strain by the addition of phaP on a plasmid, the network was also reconstituted, albeit in a slightly different arrangement from that of the wild-type network. We conclude that PhaP participates in the formation of the inclusion network.

Simultaneous optimisation of the properties of engineered composite grids for lead-acid batteries

We have developed innovative multilayer composite grids as engineered materials, which are produced in the form of grid strip in a single, highly efficient, multistage electrodeposition process. In the present paper, we are reporting, how the individual requirements for grid properties can be satisfied and optimised individually and then combined simultaneously to an overall optimum in this new family of composite grid materials. The multilayer composite materials are composed of different layers of different structures and properties, which can provide a combination of different functional properties to satisfy a more demanding total specification of mechanical behaviour, electrical performance, corrosion resistance and cycling behaviour. The paper deals with the improvement of these properties in detail and with the overall simultaneous engineering of the grid material.

Real Structure of Formamide Entrapped by AOT Nonaqueous Reverse Micelles: FT-IR and 1H NMR Studies

Noninvasive techniques such as FT-IR and (1)H NMR spectroscopy have been employed to investigate the solubilization of formamide, FA, and its aqueous solution, FA-water, by sodium 1,4-bis(2-ethylhexyl)sulfosuccinate, AOT, in heptane or isooctane reverse micelles, respectively. Partially deuterated FA (FADH) was used in the FT-IR experiments and nu(OD), n(ND) were analyzed. Also, the nu(C=O) band of FA was investigated. For AOT, the changes of the SO(3)(-) group's symmetric, nu(s), and asymmetric, nu(a), bands were also studied. The results are showing that FA is interacting strongly with the Na+ counterions of the surfactant through electrostatic interactions maintaining their hydrogen bond network present in the FA bulk. Accordingly, partially deuterated FA is "frozen" inside the aggregates and it is possible to detect, by FT-IR technique, the cis and trans isomers. Curve fitting of the nu(OD) (in the FA-water mixture) band requires use of two peaks because the band is asymmetric, not because the solubilizate molecules are present in layers of different structure. The chemical shifts of the (1)H bound to N and C of FA were studied by (1)H NMR. The comparison of the chemical shift of AOT in reverse micelles with FA and the FA-water mixture in the polar core of the aggregate shows that there is a strong preferential solvation of Na+ by FA (through electrostatic interaction) and the AOT's sulfonate group by water (through hydrogen bond interaction).

The influence of the N 2–H 2 mixture composition on the spectroscopic and temporal behaviour of glow discharge characteristics in pulse-supplied nitriding processes

The purpose of the research was to develop experimental basis for monitoring and real-time control of the plasma nitriding process performed at DC-pulsed substrate biasing. For this purpose correlation between I– U characteristics of pulsed glow discharge ( f=2 kHz, Δ=95%) and the temporal evolution of active elements concentration in the generated plasma had to be determined. Experiments were carried out in an industrial arc-vacuum device adapted to execution of continuous ‘duplex’ surface treatment processes. Investigated processes of plasma nitriding were executed at constant pressure (3 mbar) of N 2–H 2 atmosphere within a wide range of N 2 content (from 5 to 100%). Current and voltage of the discharge were automatically adjusted by the control system in such a way that the substrate temperature was kept constant at chosen value of 520 °C, enabling, depending on the atmosphere composition, creation of nitrided layers of different structures: from single-phase layer, containing diffusion zone α-Fe(N) only, to multi-phase one containing both diffusion zone α-Fe(N) and compound zone ε+ γ′, in the substrates made of hot working steel 1.2367. Optical emission spectra of generated plasma as well as temporal courses of selected emitters intensities (N 2(C), N 2 +(B), H α ) were recorded in the vicinity of the substrate. On the basis of the obtained results, the correlation between power supply parameters, gas composition and temporal evolution of the relative concentrations of the selected active species was determined. It was shown that the kinetics of the investigated emitters is strongly controlled by electrons. Three stable optical signals, suitable for monitoring of the nitriding process were extracted from the plasma spectrum.

Charge Carrier Mobility in Transport Layers of Different Structure

A survey of experimental and theoretical results on charge carrier transport in molecularly doped polymers recently obtained is presented. A key transport parameter, drift mobility, measured using conventional time-of-flight techniques is discussed.A number of polymers (polycarbonate, polystyrene, polyimide) and charge transport molecules (pyrazoloquinaline, picrylarylamine, cyanine dyes) is considered. The doped polymer systems exhibited monopolar or bipolar transport depending on electronic properties of both a dopant molecule and polymer matrix. The experimental data are compared with current theoretical models and they well fit a correlated disorder model for a dipole medium when energetic features of the transport molecules are also taken into account. The results are important for development of the most optoelectronic devices (e.g. electroluminescent, photorefractive, photovoltaic, xerographic etc.) whose operation relies critically on charge transport layers.

Sectional structures and electrical properties of ultrathin NbN/MgO bilayers on Si(100)

NbN/MgO bilayers deposited on Si(100) substrates by rf-sputtering were studied using cross-sectional transmission electron microscopy (XTEM). The XTEM results reveal that the 10-nm-thick MgO layer forms two layers of different structures, i.e., an amorphous layer (∼4 nm) and a highly (100) oriented polycrystalline layer (∼6 nm). We also found that the structure of MgO underlayers exhibits a strong effect on Tc of on-deposited NbN layers.

Theory of microtomy artefacts in arthropod cuticle

Arthropod cuticles observed in section generally present alternating clear and dark bands. These have often been interpreted in terms of superimposed layers of different structure or composition. It has been shown, however that this material is homogeneous, and is formed by a twisted arrangement of microfibrils. The dense bands correspond actually to a microtomy artefact and they form dark single spirals in certain distorted areas of the cuticle. A model was proposed, involving the interaction between knife motion and microfibrils; it will be referred to as the stepped model, since the proposed mechanism results in the formation of steps at the surface of sections, on both faces. These steps are limited by structures resembling crests or cliffs, whose regular distribution produces alternating thick and thin bands in the section. This explains the observed contrast (Bouligand, (1972)). Two very interesting models were proposed later (Gordon and Winfree, (1978)) and are referred to as the cos F model and the sand model, but steps and crests are absent in these models. However, Giraud-Guille ((1986)), has shown very clearly the existence of these crests, which seem to be quite essential in this microtomy artefact. To clarify the debate, the texts defining the initial and the two new models are reproduced here and the difficulties encountered by each model are discussed. A mathematical formulation of this artefact is presented in an appendix to the present article; this leads to a more complete discussion of the possible models. Other factors are also taken into consideration: microfibril orientation and staining. The main factor of contrasts is undoubtedly the variation in thickness over a single section, as proposed in the stepped model.

Epitaxie von dünnen Tellurschichten auf Alkalihalogeniden bei 100 °C

Abstract Te was evaporated in high vacuum (10-5 Torr) on simultaneously cleavaged alkali halides with rock salt structure. Research on the Te-films was done by transmission electron microscopy. We ob-served characteristic differences in epitaxy quality of the different substances: e. g. NaCl and LiBr showed bad, RbJ and KJ showed exceptionally good epitaxy (exclusively point diffraction pat-terns) . Reproduced experiments showed the same results as simultaneous evaporation. The expected systematic relation to analoguous d-values was however insignificant. It seems to be an "indirect epitaxy" caused by intermediate layers of different structures