Влияние химико-механической обработки кремниевых пластин на морфологию их поверхности и прочность

A previous study has illustrated that the alphaVbeta3 integrin served as the functional receptor for West Nile virus (WNV) entry into cells. Domain III (DIII) of WNV envelope protein (E) was postulated to mediate virus binding to the cellular receptor. In this study, the specificity and affinity binding of WNV E DIII protein to alphaVbeta3 integrin was confirmed with co-immunoprecipitation and receptor competition assay. Binding of WNV E DIII protein to alphaVbeta3 integrin induced the phosphorylation of focal adhesion kinase that is required to mediate ligand-receptor internalization into cells. A novel platform was then developed using the atomic force microscopy to measure this specific binding force between WNV E DIII protein and the cellular receptor, alphaVbeta3 integrin. The single protein pair-interacting force measured was in the range of 45 +/- 5 piconewtons. This interacting force was highly specific as minimal force was measured in the WNV E DIII protein interaction with alphaVbeta5 integrin molecules and heparan sulfate. These experiments provided an insight to quantitate virus-receptor interaction. Force measurement using atomic force microscopy can serve to quantitatively analyze the effect of candidate drugs that modulate virus-host receptor affinity.

Multilayer structures with depth-graded spacing can show a high reflectivity in a broad energy passband for hard X-rays if the interface roughness/diffuseness is controlled and minimized. We present a study of several multilayer systems deposited by DC magnetron sputtering on silicon wafers and superpolished fused silica substrates. The material combinations discussed are W/Si, WSi2/Si, W/C, Pt/C, Ni/C, Ni/B4C, and Mo/Si. The deposition method used was DC magnetron sputtering at low argon pressures (1.5 to 5 mT). The characterization methods used were: Atomic Force Microscopy in tapping mode, stylus profilometry, Rutherford backscattering, cross sectional TEM, and specular X-ray reflectivity (XRR) scans at 8.05 keV. Different process parameters were varied in order to optimize the interface roughness/diffuseness (sigma) that was measured by XRR scans.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Enamel translucency, essential for the aesthetic appeal of teeth, is primarily determined by its thickness, quality, and refractive index. Several factors, including age, genetics, diet, oral hygiene practices, fluoride exposure, and acidic challenges, can influence enamel translucency. Tobacco use, in particular, leads to significant alterations in enamel appearance by penetrating its micropores, causing yellowing and browning. Prolonged exposure to tobacco results in demineralization, increasing enamel porosity and reducing its translucency. Over time, this exposure leads to permanent discoloration and structural degradation, rendering teeth dull and opaque. To assess these changes, various methods such as visual examinations, digital photography, spectrophotometry, stylus profilometry, and atomic force microscopy (AFM) are utilized. This study analyzed human enamel samples, including one unstained sample (Grade 0) and three tobacco-stained samples (Grades 1-3) according to Modified Lobene Stain Index (MLSI), to investigate the impact of tobacco exposure on enamel structure. The samples were thoroughly cleaned and dried to ensure accurate results. High-resolution AFM imaging was employed to assess surface roughness, porosity, and microstructural changes induced by tobacco staining. A stylus profilometer was used to trace the surface topography, providing detailed measurements of surface irregularities. Additionally, a spectrophotometer was utilized to evaluate the optical properties of the enamel, focusing on changes in translucency and light absorption due to tobacco exposure. AFM analysis revealed a clear progression of enamel surface roughness from Grade 0 to Grade 3. The Sa and Sq values increased significantly with the severity of tobacco staining, indicating greater surface degradation. The stylus profilometer data corroborated these findings, with rising Ra values as the degree of staining intensified, highlighting the topographical alterations caused by tobacco exposure. Spectrophotometric analysis further demonstrated a decrease in enamel reflectance and an increase in light absorption from mild to severe staining, underscoring the detrimental optical effects of tobacco on enamel. The combined use of AFM, stylus profilometry, and spectrophotometry provided a comprehensive assessment of the impact of tobacco staining on enamel translucency and surface roughness. The findings show that as staining severity increases, enamel translucency diminishes, and surface roughness worsens. These alterations not only affect the aesthetic appearance of teeth but also have potential implications for enamel functionality and long-term oral health.

The foundation has a function to hold the load in the form of axial load, lateral load and moment. The axial load on the pile foundation is supported by the pole end resistance and pile friction, while the lateral load on the pile foundation is supported by the relation of the blanket area along with the pile with the ground in the lateral direction. Lateral load causes lateral deflection in which the magnitude of deflection must not exceed the permissible lateral deflection limit of 2.54 cm. The determining factors in lateral deflection are the type of pile foundation, soil type, and the magnitude of the force that occurs. The foundation of a single pile in which the number of one pile, when embedded in clay soil, needs to be investigated for the magnitude of lateral deflection that occurs, this is due to the changing nature of the clay when under the influence of high or low water content. The foundation of the pile uses a concrete head with a condition of a free end with a cylindrical shape with a diameter of 60 cm that is not solid with a wall thickness of 10 cm and a compressive strength of concrete of 60 MPa. Clay soil data uses soil drilling test data in Wirosari, Grobogan, Central Java. The planning method used is the finite element method (PLAXIS program) and the finite difference method (py curve and the ALLPILE program) with lateral load variations of 10 kN, 15 kN and 20 kN given to the top end of the pole with the principle of giving trial and error loads. The results of the calculation of the lateral deflection of the pile on the py curve method with a finite-difference resolution, the ALLPILE program, and the PLAXIS program respectively with a lateral load of 10 kN are 0.0629 cm; 1.21 cm; 0.27 cm, lateral loads of 15 kN are 0.0943 cm; 2.13 cm; 0.4051 cm, and a lateral load of 20 kN is 0.1258 cm; 3.14 cm; 0.5402 cm. Thus the lateral deflection load limit is 15 kN, so as not to exceed the permissible lateral deflection limit of 2.54 cm. The recommended method used is the ALLPILE program to better get the level of security from the lateral deflection of the pole when applied in the field

Recently, Binnig, Quate, and Gerber developed the atomic force microscope (AFM), an instrument which senses minute (10-12 – 10-8 N) forces between a sharp tip and a sample surface [1], In addition to enabling the study of solid-solid interactions on a unprecedentedly small scale, the AFM provides a general method for doing non-destructive surface profilometry at a resolution better than 10 nm and perhaps down to the atomic level. In this paper we review the principles of the AFM, discuss its potential resolution and data rate, describe our new AFM design, and present some initial results. We have obtained three dimensional surface profiles with 20 nm lateral resolution, which to our knowledge is better than what has been attained previously by stylus profilometry.

Toward the application to the tapping mode AFM (Atomic Force Microscope), we propose a new control method to keep the state of a soft impact between an object surface and the tip of a cantilever whose supporting point is periodically and laterally excited. In the practical usage of AFM, the surface of the object is scanned by the excited cantilever. Depending on the profile of the surface, the distance between the surface and the center of the excitation is varied and then, the state of the contact is changed. To keep the state of contact, the center of the excitation is automatically shifted in AFM. As a result, we can know the profile of the object from the shift of the center while scanning. By the way, it is known that various bifurcations of the responses of the beam occur according to impact conditions and variation of the excitation frequency. In our previous study, we indicated theoretically and experimentally that when the excitation frequency N is set to 2.5 times the first natural frequency ω1 of the cantilever, i.e., N=2.5ω1, the contact produces the frequency component of the 1.25 time the first natural frequency in the cantilever response, i.e., 1.25ω1. In this paper, by using this phenomenon, we propose a control method to shift the center of the excitation according to the profile of the object surface, keeping soft contact. For this purpose, a real-time signal processing method is suggested to determine the magnitude of the targetted frequency component. Also, a servo system is designed to periodically excite and to control the center of the excitation precisely. Finally, validity of the proposed control method is experimentally confirmed by using a macro-beam.

ABSTRACTThe atomic force microscope (AFM) can be used in dynamic tipping mode as an effective lithography technique capable of manufacturing nanometer sized devices on the surface of a silicon wafer with a higher resolution surface characterization. The most difficult challenge in fabrication of nanostructure based on AFM nano-oxidation approach is the way of controlling an electric field between a cantilever probe tip and a silicon wafer. A water bridge builds up between the tip and the wafer, resulting in the oxidation due to the high electric field in the region. A reconstructive AFM system for nano-oxidation with a tapping model, implemented in an air, was developed. The presented AFM implements the increasing of electric field intensity by analyzing the impact voltage from −1 V to −5 V, electric field, and ion concentrations at the ambient/oxide and oxide/silicon interfaces, while the growth of thin oxides assumes a single liquid/silicon interface, which is modeled as an infinitely long conducting plane. Therefore, particle distribution for the surface charge density is generated for topography simulations. Based on the control-parameters, an enhanced electrical field of up to 1010 V/m can be obtained, which provides a powerful support for controllable experimental study of nanostructures fabrication with AFM tip induced local anodic oxidation. This showed the dependence of applied voltage types and various nanostructures and life time of AFM tip, by controlling tip-sample position in nanolithography processes is an important factor for controlling the aspect electric field distribution. And the effect of different parameters on enhancement distribution was performed and analyzed in this paper.

The residual stress distribution for two strategies of asymmetric quenching in Al-Zn-Mg-Cu aluminum alloy plates has been simulated using the finite element method. The results show that for asymmetric quenching between the upper and lower surfaces, the through-thickness asymmetric quenching residual stress distribution lies between the two distributions corre-sponding to the heat transfer coefficients on the upper and lower surfaces respectively. The surface and central stress magnitudes are equal to the average of the stress magnitudes corresponding to the two heat transfer coefficients. For asymmetric quenching of a single surface, the surface stress distribution is the same as the heat transfer coefficient distribution and the stress magnitude is equal to the stress magnitude corresponding to the average value of the heat transfer coefficients at each location. However, the center quench residual stress distribution is approximately uniform and the stress magnitude is equal to the average of the stress magnitudes corresponding to the maximum and minimum heat transfer coefficients.

This study proposes a surface profile and roughness measurement system for a fibre-optic interconnect based on optical interferometry. On the principle of Fizeau interferometer, an interference fringe is formed on the fibre end-face of the fibre-optic interconnect, and the fringe pattern is analysed using the Fast Fourier transform method to reconstruct the surface profile. However, as the obtained surface profile contains some amount of tilt, a rule for estimating this tilt value is developed in this paper. The actual fibre end-face surface profile is obtained by subtracting the estimated tilt amount from the surface profile, as calculated by the Fast Fourier transform method, and the corresponding surface roughness can be determined. The proposed system is characterized by non-contact measurement, and the sample is not coated with a reflector during measurement. According to the experimental results, the difference between the roughness measurement result of an Atomic Force Microscope (AFM) and the measurement result of this system is less than 3 nm.

When the AFM cantilever is mounted with a sharp diamond tip, in addition to controlling both the applied normal load on the tip and other machining parameters by the AFM electrical components, it is capable of conducting micro/nano-machining on the surface of single crystal silicon. Firstly in this research work the diamond tip based single asperity cutting experiments are conducted on silicon surface with different normal loads and cutting speed, in aiming to investigate the AFM based microcutting process and material removal mechanism for silicon-like brittle material on nanoscale. Secondly, the micro/nano-machining experiments are conducted on single crystal silicon surface with different detecting approaches for characterizing the features of the micro/nano-machined region in terms of material removal mechanism and chips forming characteristic under different normal loads. Furthermore, the contact interaction mechanism existed between the AFM diamond tip and the machined silicon surface during the micro/nano-machining process is simulated with finite element method. Finally, the wear mechanism of an atomic force microscope (AFM) diamond tip when conducting micro/nano-machining on a single crystal silicon surface is empirically analyzed. The results indicate that the AFM based v has a precisely dimensional controllability and a good surface quality on nanometer scale.

Surface roughness affects the functional properties of surfaces, including adhesion, friction, hydrophobicity, biological response, and electrical and thermal transport properties. However, experimental investigations to quantify these links are often inconclusive because surfaces are fractal-like, and the values of measured roughness parameters depend on measurement size. Here, we demonstrate the characterization of topography of an ultrananocrystalline diamond (UNCD) surface at the angstrom scale using transmission electron microscopy (TEM), as well as its combination with conventional techniques to achieve a comprehensive surface description spanning 8 orders of magnitude in size. We performed more than 100 individual measurements of the nanodiamond film using both TEM and conventional techniques (stylus profilometry and atomic force microscopy). While individual measurements of root-mean-square (RMS) height, RMS slope, and RMS curvature vary by orders of magnitude, we combine the various techniques using the power spectral density and use this to compute scale-independent parameters. This analysis reveals that "smooth" UNCD surfaces have an RMS slope greater than 1, even larger than the slope of the Austrian Alps when measured on the scale of a human step. This approach of comprehensive multiscale roughness characterization, measured with angstrom-scale detail, will enable the systematic evaluation and optimization of other technologically relevant surfaces, as well as systematic testing of the many analytical and numerical models for the behavior of rough surfaces.

For prediction of the short and long-term geomechanical behaviour of a deep geological repository for nuclear waste, the present-day 3D in-situ stress is a key parameter. However, in Germany the knowledge concerning the crustal stress state is still quite low. It is mainly based on data from the World Stress Map (WSM) project providing data of the orientation of the maximum horizontal stress (SHmax) and a new compilation of stress magnitude data providing magnitudes of SHmax and the minimum horizontal stress (Shmin). However, these two databases still provide only unequally distributed data records and in particular horizontal stress magnitude data records are only reliable at a dozen locations all over Germany. Thus, for an in-situ stress field prediction geomechanical-numerical models - calibrated on available horizontal stress magnitudes – are used. They enable a continuum-mechanics based description of the 3D present-day stress state and can resolve lateral and especially vertical variations. Two 3D geomechanical-numerical models of Germany have been published during the initial phase of the SpannEnD project (2018-2022). In the follow-up project SpannEnD 2.0 a new model has been set-up based on a new geological model enabling new insights into present-day crustal stress field of Germany, in particular due to higher vertical resolution. We also use a significantly enlarged stress magnitude database for model calibration.The new 3D geomechanical-numerical model combines information of 27 regional geological models and comprehensive additional data. It comprises 49 geological units parametrized with elastic rock properties (Young’s modulus and Poisson’s ratio) and rock densities. Linear elasticity is assumed and the finite element method (FEM) is used to solve the partial differential equations that describe the equilibrium of gravitational and surface forces. Overall, the model contains ~10 million hexahedral elements providing a lateral resolution of 4 km and a vertical resolution of up to 45 m in the uppermost 5 km. The model results show an overall good fit with stress magnitudes used for calibration indicated by a mean of the absolute stress differences of ~3 MPa for Shmin and of ~5 MPa for SHmax. Furthermore, the results agree well with additional data sets - not used for calibration - e.g., an absolute mean deviation of the orientation of SHmax with regard to WSM data of ~10°.

Determination of fractal rough surface of polypyrrole film: AFM and electrochemical analysis

A series of tests was conducted using a reciprocating tribometer to evaluate the tribological performance of a plasma electrolytic oxidation (PEO) treated eutectic aluminium-silicon alloy and was compared with a more conventional nickel-ceramic (Ni-SiC) coating as a reference. The counterpart was a gas-nitrided steel top piston ring and the lubricant was a group III base oil blended with standard detergent and dispersant additives, both with and without dispersions of very fine particles of molybdenum disulphide as a friction modifier. Scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy, and stylus profilometry were employed to characterize the morphology, elemental composition, and surface force analysis of the tribofilm and the wear profile. The tribological performance of the PEO transformed surface was found to be similar to the Ni-SiC coating in the short-duration tribometer experiments undertaken with fully flooded lubrication and at low-speed conditions, with potentially greater durability in the longer term given the properties of the transformed surface layer.

Ultra-short pulsed laser ablation of highly oriented pyrolytic graphite