scholarly journals The Growth Behavior of Amorphous Hydrogenated Carbon a-C:H Layers on Industrial Polycarbonates—A Weak Interlayer and a Distinct Dehydrogenation Zone

2021 ◽  
Vol 7 (3) ◽  
pp. 59
Author(s):  
Torben Schlebrowski ◽  
Melanie Fritz ◽  
Lucas Beucher ◽  
Yongxin Wang ◽  
Stefan Wehner ◽  
...  
Keyword(s):  
Data Storage ◽  
Surface Composition ◽  
Base Material ◽  
Carbon Layer ◽  
Grain Structure ◽  
Interlayer Region ◽  
Weak Interlayer ◽  
The Stability ◽  
20 Nm ◽  
Amorphous Hydrogenated Carbon

Polycarbonate (PC) is a material that is used in many areas: automotive, aerospace engineering and data storage industries. Its hardness is of particular importance, but some applications are affected by its low wettability or scratch susceptibility. This can be changed either by blending with other polymers, or by surface modifications, such as the application of an amorphous hydrogenated carbon layer (a-C:H). In this study, individual a-C:H layers of different thicknesses (10–2000 nm) were deposited on PC by RF PECVD. Both the layer morphology with AFM and SEM and the bonding states of the carbon on the surface with synchrotron-assisted XPS and NEXAFS were studied. The aim was to investigate the coatability of PC and the stability of the a-C:H. Special attention was paid to the interlayer region from 0 to 100 nm, since this is responsible for the layer to base material bonding, and to the zone of dehydrogenation (from about 1000 nm), since this changes the surface composition considerably. For PC, the interlayer was relatively small with a thickness of only 20 nm. Additionally, a correlation was found between the evolving grain structure and the development of the C‒H peak according to NEXAFS C K-edge measurements.

scholarly journals Performance of Iron-Functionalized Activated Carbon Catalysts (Fe/AC-f) on CWPO Wastewater Treatment

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 337
Author(s):  
Sara Mesa Medina ◽  
Ana Rey ◽  
Carlos Durán-Valle ◽  
Ana Bahamonde ◽  
Marisol Faraldos
Keyword(s):  
Wastewater Treatment ◽  
Activated Carbon ◽  
Landfill Leachate ◽  
Surface Composition ◽  
Treatment Plant ◽  
Reaction Medium ◽  
Pollutant Removal ◽  
Operating Conditions ◽  
Water Matrix ◽  
The Stability

Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemental analysis, emission spectroscopy, XPS), textural (N2 isotherms), and structural characteristics (XRD). All the Fe/AC-f catalysts were evaluated in the degradation of phenol in ultrapure water matrix by catalytic wet peroxide oxidation (CWPO). Complete pollutant removal at short reaction times (30–60 min) and high TOC reduction (XTOC = 80 % at ≤ 120 min) were always achieved at the conditions tested (500 mg·L−1 catalyst loading, 100 mg·L−1 phenol concentration, stoichiometric H2O2 dose, pH 3, 50 °C and 200 rpm), improving the results found with bare activated carbon supports. The lability of the interactions of iron with functionalized carbon support jeopardizes the stability of some catalysts. This fact could be associated to modifications of the induced surface chemistry after functionalization as a consequence of the iron immobilization procedure. The reusability was demonstrated by four consecutive CWPO cycles where the activity decreased from 1st to 3rd, to become recovered in the 4th run. Fe/AC-f catalysts were applied to treat two real water matrices: the effluent of a wastewater treatment plant with a membrane biological reactor (WWTP-MBR) and a landfill leachate, opening the opportunity to extend the use of these Fe/AC-f catalysts for complex wastewater matrices remediation. The degradation of phenol spiked WWTP-MBR effluent by CWPO using Fe/AC-f catalysts revealed pH of the reaction medium as a critical parameter to obtain complete elimination of the pollutant, only reached at pH 3. On the contrary, significant TOC removal, naturally found in complex landfill leachate, was obtained at natural pH 9 and half stoichiometric H2O2 dose. This highlights the importance of the water matrix in the optimization of the CWPO operating conditions.

scholarly journals Parametric Instability of a Traveling Plate Partially Supported by a Laterally Moving Elastic Foundation

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
V. Kartik ◽  
J. A. Wickert
Keyword(s):  
Data Storage ◽  
Parametric Instability ◽  
Primary Resonance ◽  
Free Edge ◽  
Moving Plate ◽  
Torsional Mode ◽  
Plane Vibration ◽  
Out Of Plane ◽  
Axially Moving ◽  
The Stability

The parametric excitation of an axially moving plate is examined in an application where a partial foundation moves in the plane of the plate and in a direction orthogonal to the plate’s transport. The stability of the plate’s out-of-plane vibration is of interest in a magnetic tape data storage application where the read/write head is substantially narrower than the tape’s width and is repositioned during track-following maneuvers. In this case, the model’s equation of motion has time-dependent coefficients, and vibration is excited both parametrically and by direct forcing. The parametric instability of out-of-plane vibration is analyzed by using the Floquet theory for finite values of the foundation’s range of motion. For a relatively soft foundation, vibration is excited preferentially at the primary resonance of the plate’s fundamental torsional mode. As the foundation’s stiffness increases, multiple primary and combination resonances occur, and they dominate the plate’s stability; small islands, however, do exist within unstable zones of the frequency-amplitude parameter space for which vibration is marginally stable. The plate’s and foundation’s geometry, the foundation’s stiffness, and the excitation’s amplitude and frequency can be selected in order to reduce undesirable vibration that occurs along the plate’s free edge.

scholarly journals CLINICAL AND ANATOMICAL RESTORATION OF THE MASTICATORY GROUP OF TEETH WITH A BURDENED GENERAL STATUS

2019 ◽  
Vol 23 (5) ◽  
pp. 202-207
Author(s):  
E. O Kudasova ◽  
N. I Kagramanova ◽  
Ekaterina Vladimirovna Kochurova ◽  
L. V Gavrushova ◽  
V. N Nikolenko ◽  
...  
Keyword(s):  
Base Material ◽  
Spherical Shape ◽  
Gastrointestinal Diseases ◽  
Secondary Caries ◽  
Dental Examination ◽  
Filling Materials ◽  
Hard Tissues ◽  
The Stability ◽  
Group B ◽  
The Cost

Objective. The chewing group of teeth is intended for equally crusher of food and forming food lump. This group is presented by two kinds of teeth: premolars and molars, and more often affected by caries, because a lot of retention zones are contribute to the active delay of plaque and the appearance of carious cavities. It is happening before 18 years. In the absence of these teeth or badly damaged of the crown part, food is chewed badly and as a result, stomach contain extremely large pieces. But its size is impossible for physiological digestion by the gastrointestinal tract and as a consequence the occurrence of gastrointestinal diseases. According to modern data, to work with lesions of hard tissues of the teeth, namely the chewing group of teeth, it is advisable to use composite light-curing microhybrid materials, which are characterized by particles close to the spherical shape. The aim of this study is determination of the possibility using a budgetary aesthetic composite for restorative restoration of the masticatory group of teeth in patients with a burdened anamnesis. Material and methodology. Was examined 22 people with aesthetic and anatomical disorders of the vestibular and occlusal surface of the hard tissues of the chewing group of teeth (n=154), followed by their recovery. The stability of filling materials was assessed according to Ryge-criteria: color coincidence, discoloration of the marginal segment, marginal adaptation, anatomical shape integrity, restoration surface, secondary caries. Results. Clinical and dental examination showed all the above violations of existing restorations (according to Ryge classification) in patients before restoration manipulations. After 1 week after the restoration, the examination showed that both groups of composites completely restore the anatomical and aesthetic chewing group of teeth and meet all the criteria. After 3 months, the assessmen t of the restoration by the composite of group A and group B did not reveal evidence of secondary caries on the perimeter of the restorations. Clinical and dental examination after 6 months showed minor changes in the restorations of composites of both groups in assessing the stability of color (90.9% and 83.3% in groups A and B) and the stability of surface polishing (89.6% and 81.8%, respectively). Discussion. The main signs of the restoration, which are undergoing changes, are discoloration, as well as the preservation of the smoothness of the surface regardless of the cost and branding of the base material.

scholarly journals Facilitating TiB2 for Filtered Vacuum Cathodic Arc Evaporation

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 244
Author(s):  
Tomasz L. Brzezinka ◽  
Jeff Rao ◽  
Jose M. Paiva ◽  
Ibon Azkona ◽  
Joern Kohlscheen ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Deposition Rate ◽  
Axial Magnetic Field ◽  
Electrical Potential ◽  
Base Material ◽  
Hard Coatings ◽  
Grain Structure ◽  
High Deposition Rate ◽  
Bulk Hardness ◽  
Arc Evaporation

TiB2 is well established as a superhard coating with a high melting point and a low coefficient of friction. The brittle nature of borides means they cannot be utilised with arc evaporation, which is commonly used for the synthesis of hard coatings as it provides a high deposition rate, fully ionised plasma and good adhesion. In this work, TiB2 conical cathodes with non-standard sintering additives (carbon and TiSi2) were produced, and the properties of the base material, such as grain structure, hardness, electrical resistivity and composition, were compared to those of monolithic TiB2. The dependence of the produced cathodes’ electrical resistivity on temperature was evaluated in a furnace with an argon atmosphere. Their arc–evaporation suitability was assessed in terms of arc mobility and stability by visual inspection and by measurements of plasma electrical potential. In addition, shaping the cathode into a cone allowed investigation of the influence of an axial magnetic field on the arc spot. The produced cathodes have a bulk hardness of 23–24 GPa. It has been found that adding 1 wt% of C ensured exceptional arc-spot stability and mobility, and requires lower arc current compared to monolithic TiB2. However, poor cathode utilization has been achieved due to the steady generation of cathode flakes. The TiB2 cathode containing 5 wt% of TiSi2 provided the best balance between arc-spot behaviour and cathode utilisation. Preventing cathode overheating has been identified as a main factor to allow high deposition rate (±1.2 µm/h) from TiB2-C and TiB2-TiSi2 cathodes.

Double Laser Crystallization (DLC) of 50 Nanometer and 20 Nanometer Amorphous Silicon Film for Thin Film Transistors (TFTS) Application

2005 ◽  
Author(s):  
Li Xu ◽  
Costas P. Griogoropoulos
Keyword(s):  
Electron Microscope ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Silicon Film ◽  
Solidification Process ◽  
Grain Structure ◽  
Laser Crystallization ◽  
Surface Reflection ◽  
Microscope Images ◽  
20 Nm

Ultra-large grain poly-crystalline silicon has been formed in 20 nm and 50 nm amorphous silicon films by the double laser crystallization (DLC) method. Surface reflection properties of such thin films upon laser irradiation were calculated. In-situ images were captured to monitor the transient melting and solidification process of 50 nm silicon film in order to understand the crystallization induced by steep laser intensity gradients. SEM (scanning electron microscope) images of crystallized 50 nm film after Secco etch revealed grain size up to 10 m while plane-view TEM (transmission electron microscope) images of 50 nm film also showed perfect crystalline structure inside the grains. AFM (atomic force microscope) images were also taken to show the topology of the grain structure and RMS of 20 nm film.

Friction-Induced Dynamics of Axially-Moving Media in Contact With an Actively-Positioned Surface

2008 ◽  
Author(s):  
V. Kartik ◽  
Evangelos Eleftheriou
Keyword(s):  
Data Storage ◽  
Surface Friction ◽  
Design Parameters ◽  
Moving Medium ◽  
Critical Design ◽  
Flexible Material ◽  
Potential Benefits ◽  
Axially Moving ◽  
The Stability ◽  
Moving Media

The dynamics of an axially-moving flexible medium are examined in the context of an application where the medium is partially supported by a frictional surface, that actively-orients itself relative to the direction of transport. The stability and motion of the medium are of interest in a magnetic tape data storage application where the orientation of a sensing surface is continuously altered in order to ‘follow’ the medium’s motion. Moving media that are in contact with such guiding surfaces experience friction excitations induced by the relative motion in addition to what is observed with a stationary guiding surface. Friction-induced bending moments, as well as tension fluctuation beyond the permissible limits for the flexible material can erode the potential benefits of such active positioning. This paper describes some of these dynamic phenomena using the simplified example of a planar guiding surface whose orientation is dynamically altered relative to the moving medium. A physical model for the friction-induced excitation of the moving medium is developed, and the dynamics are analyzed for their effect on critical design parameters such as the achievable bandwidth of the active control algorithm, as well as with respect to constraints on the geometry and positioning of the guiding surface.

Reduction of Charging in Biological Electron Cryomicroscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 365-366
Author(s):  
M.B. Sherman ◽  
J. Brink ◽  
W. Chiu
Keyword(s):  
Electron Diffraction ◽  
Ion Beam ◽  
High Energy ◽  
Carbon Layer ◽  
Thin Layers ◽  
Biological Macromolecules ◽  
Electron Cryomicroscopy ◽  
Obvious Effect ◽  
Diffraction Patterns ◽  
The Stability

High resolution imaging in electron cryomicroscopy of biological macromolecules is strongly affected by beam-induced charging1. Charging is often expressed in frozen or glucose-embedded specimens as an increase in apparent mass-thickness of the irradiated area. Another obvious effect of charging is blurring of both the unscattered beam and reflections in electron diffraction patterns recorded from crystalline specimens. Coating of ice-embedded specimens with a carbon layer helps to improve the stability of the ice and probably reduce charging of the specimen. Coating in a Gatan ion-beam coater (model 681) of glucose-embedded specimens with thin layers of various conductive materials did reduce charging but the specimens were damaged by the high energy ions used for the coating. In general, coating resulted in much weaker reflections in electron diffraction patterns obtained from coated crystals and faster resolution fall-off.We modified the Gatan coater by outfitting it with a new chamber that replaced the ion-beam deposition capability for thermal evaporation of carbon rods (Fig. 1).

scholarly journals Channel Length Biasing for Improving Read Margin of the 8T SRAM at Near Threshold Operation

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 611 ◽  
Author(s):  
Ik Joon Chang ◽  
Yesung Kang ◽  
Youngmin Kim
Keyword(s):  
Threshold Voltage ◽  
Supply Voltage ◽  
Random Access ◽  
Channel Length ◽  
Voltage Level ◽  
Exact Data ◽  
Optimum Energy ◽  
The Stability ◽  
20 Nm ◽  
Near Threshold

Reducing a supply voltage in order to minimize power consumption in memory is a major design consideration in this field of study. In static random access memory (SRAM), optimum energy can be achieved by reducing the voltage near the threshold voltage level for near threshold voltage computing (NTC). However, lowering the operational voltage drastically degrades the stability of SRAM. Thus, in conventional 6T SRAM, it is almost impossible to read exact data, even when a small process variation occurs. To address this problem, an 8T SRAM structure is proposed which can be widely used for improving the read stability at lower voltage operation. In this paper, we investigate the channel length biasing effect on the read access transistor of the 8T SRAM in NTC and compare this with 6T SRAM. Read stability can be improved by suppressing the leakage current due to the longer channel length. Simulation results show that, in NTC, up to a 12× read-error reduction can be achieved by the 20 nm channel length biasing in the 8T SRAM compared to 6T SRAM.

Thermal Stability of Ultrafine Grains in Al-Fe-Mn-Si Foils Prepared by ARB and Subsequent Rolling

2008 ◽  
Vol 584-586 ◽  
pp. 905-910 ◽  
Author(s):  
Petr Homola ◽  
Margarita Slámová ◽  
P. Sláma ◽  
Miroslav Cieslar
Keyword(s):  
Thermal Stability ◽  
Structural Changes ◽  
High Strength ◽  
Electron Back Scatter Diffraction ◽  
Grain Structure ◽  
Fine Grain ◽  
Hardness Increase ◽  
Cold Rolled ◽  
The Stability ◽  
Thermal Stability Of

Accumulative Roll Bonding (ARB) is a severe plastic deformation process that allows producing ultrafine-grained materials (UFG). UFG sheets exhibit enhanced strength and very fine grain structure. Foils used as fins in heat exchangers have to be very thin but must exhibit high strength combined with relatively high formability. Thus, materials produced using ARB may fulfil the exacting requirements on foil properties for such applications. The thermal stability of Al-Fe- Mn-Si foils produced using ARB and subsequent cold rolling was studied and compared with conventionally cold rolled (CCR) counterparts. The stability was assessed by isothermal annealing in the temperature range from 200 to 450 °C. Electron back scatter diffraction in a scanning electron microscope and transmission electron microscopy examinations of foils microstructure in the deformed and annealed states allowed the monitoring of structural changes. The magnitude of mechanical properties changes due to annealing was evaluated by microhardness measurements. Significant hardness increase was observed after annealing at 200 °C only in the ARB samples and was assigned to an annealing-induced hardening. The CCR foil exhibits higher non-recrystallized fraction and smaller mean lamellae boundary spacing in the temperature interval of 200-250 °C than ARB foils. The annealing at 450 °C results in identical hardness values and fully recrystallized microstructure of all foils, regardless the method used for their manufacturing. However, the ARB samples show higher stability of the refined substructure than their cold rolled counterparts due to continuous recrystallization occurring in the ARB foils.

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