Rq Parameters Research Articles

The effect of terminal group of hole injection self-assembled monolayers on the performance of optoelectronic devices on ITO anodes

We demonstrate the effect on the performance of conventional (Indium tin oxide (ITO)/N,Nj-Di (1- naphthyl)-N,Nj-diphenyl-(1,1-biphenyl)-4,4-diamine (NPB)/Tris-(8-hydroxyquinoline)aluminum (Alq3)/LiF/Al) optoelectronic devices when the ITO surface is modified with various types of self-assembled monolayer (SAM)s such as 3-(trimethoxysilyl)propylamine (NH2SAM), Trimethoxy (propyl)silane CH3SAM, and Trimethoxy (3,3,3-trifluoropropyl)silane (F3SAM). The head functional group and chain configuration are trimethoxysilylpropyl (-(CH3O)3Si(CH2)2) and the tail groups distinguished SAMs (-NH2, -CH3, and -CF3). The contact angles of NH2SAM, CH3SAM, and F3SAM deposited on ITO and ITO were 70.7°, 81.42°, 68.23°, and 30.85°, respectively. The SAM-modified ITO's surface morphology Rpv and Rq parameters were reduced from 31.02 nm to 2.0 nm and 1.18 nm–0.26 nm. The work functions values of ITO, ITO/NH2SAM, ITO/CH3SAM and ITO/F3SAM measured by UPS were 4.99eV, 4.39, 5.09 and 5.69eV, respectively. The maximum luminance of the SAM-modified device increased to 166-fold, and the current density 105-fold, compared to the unmodified device when the operating voltage is set to 11 V. Current and power efficiency increased by 1.9 and 2-fold, respectively. The hole injection conditions are enhanced and the hole injection barrier height between ITO/NPB is reduced.

In Vitro Effect of Acidic Solutions and Sodium Fluoride on Surface Roughness of Two Types of CAD-CAM Dental Ceramics.

Objectives This study assessed the effect of immersion in acidic solutions and sodium fluoride on surface roughness of dental ceramics. Materials and Methods 40 blocks of Vitablocs Mark II and IPS e.max CAD (5 × 5 × 3) were prepared. The samples were divided into five groups (n = 8) for immersion in artificial saliva (control), artificially prepared gastric acid, acetic acid, 0.02% sodium fluoride + gastric acid, and 0.02% sodium fluoride + acetic acid. The samples were immersed for 168 hours in the respective solutions except for sodium fluoride, in which the samples were immersed for 69 hours. The surface roughness of samples was measured before and after immersion using a profilometer. The surface roughness changes of three specimens of each group were evaluated by scanning electron microscopy (SEM). Data were analyzed using one-way and two-way ANOVA, Tukey's test, and independent t-test. Results Significant changes were noted in Ra (P=0.002) and Rq (P < 0.0001) in both types of ceramics. The lowest changes in Ra and Rq parameters were seen in artificial saliva and gastric acid and highest changes occurred following immersion in 0.02% sodium fluoride + acetic acid and 0.02% sodium fluoride + gastric acid, respectively. Changes in Rz were also significant following immersion in Vitablocs Mark II (P < 0.05). Immersion in 0.02% sodium fluoride + gastric acid and 0.02% sodium fluoride + acetic acid produced a rougher surface on both types of ceramics (SEM). Conclusion Exposure of Vitablocs Mark II CAD and IPS e.max CAD to 0.02% sodium fluoride + gastric acid and 0.02% sodium fluoride + acetic acid significantly increased their surface roughness, while for Vitablocs Mark II, lager defects were seen on its surface.

The Effect of Various Surface Treatments of Ti6Al4V on the Growth and Osteogenic Differentiation of Adipose Tissue-Derived Stem Cells

The physical and chemical properties of the material surface, especially its roughness and wettability, have a crucial effect on the adhesion, proliferation, and differentiation of cells. The aim of this study is to select the most appropriate surface modifications of Ti6Al4V implants for pre-colonization of the implants with adipose tissue-derived stem cells (ASCs) in order to improve their osseointegration. We compared the adhesion, growth, and osteogenic differentiation of rat ASCs on Ti6Al4V samples modified by methods commonly used for preparing clinically used titanium-based implants, namely polishing (PL), coating with diamond-like carbon (DLC), brushing (BR), anodizing (AND), and blasting (BL). The material surface roughness, measured by the Ra and Rq parameters, increased in the following order: PL &lt; DLC ˂ BR ˂ AND ˂ BL. The water drop contact angle was in the range of 60–74°, with the exception of the DLC-coated samples, where it was only 38°. The cell number, morphology, mitochondrial activity, relative fluorescence intensity of osteogenic markers RUNX2, type 1 collagen, and osteopontin, the calcium consumption by the cells and the alkaline phosphatase activity depended on the surface roughness rather than on the surface wettability of the materials. Materials with a surface roughness of several tens of nanometers (Ra 60–70 nm), i.e., the BR and AND samples, supported a satisfactory level of cell proliferation. At the same time, they achieved the highest level of osteogenic cell differentiation. These surface modifications therefore seem to be most suitable for pre-colonization of Ti6Al4V implants with stem cells pre-differentiated toward osteoblasts, and then for implanting them into the bone tissue.

Effect of four different finishing and polishing systems on resin composites: roughness surface and gloss retention evaluations.

Finishing and polishing procedures play a crucial role to achieve the best aesthetic result of direct restorations. Many manufacturers to the clinicians offer different finishing and polishing systems. This study aims to examine the behavior of four different finishing and polishing systems on the roughness, gloss and morphology surface of one resin composite. Twelve Filtek XTE Supreme (3M ESPE) discs were prepared and divided into 4 groups (N.=3), depending on the different finishing and polishing systems: Group 1 (GP1) Sof-Lex Extra-Thin XT discs; Group 2 (GP2) Sof-Lex Coarse black disc, multi-fluted bur, Sof-Lex Diamond Polishing System Spirals; Group 3 (GP3) Sof-Lex Coarse black disc, multi-fluted bur, Sof-Lex Diamond Polishing System Spirals, Diamond Twist SCL; Group 4 (GP4) with Sof-Lex Coarse black disc, multi-fluted bur and Occlubrush. The roughness and gloss were evaluated and then samples examined by Scanning Electron Microscopy (SEM) to analyse the morphology after finishing and polishing. Regarding the surface roughness, GP1 and GP2 showed similar values for Ra, Ry, Rz and Rq parameters; while GP3 displayed the lowest values in all parameters; GP4 had the highest Ra value. Regarding the gloss, the values decreased as follows: GP3>GP2=GP4>GP1 (P<0.05). Scanning electron micrographs showed the abrasion of the samples with an increase in the surface roughness in GP1 and GP4. One-way ANOVA followed by Tukey's Test was used for statistical evaluations (P<0.05). The roughness and gloss surface of resin composites depend on the finishing and polishing systems used. This study demonstrates that satisfactory gloss outcomes are obtained using a system based on diamond paste.

Struktura geometryczna powierzchni po toczeniu wykończeniowym stali martenzytycznej AISI 630

The surface texture of martensitic AISI 630 steel after the finishing turning is described. The tests were carried out under dry and cooling conditions. Experiments were carried out under variable cutting speeds and feeds and under a constant depth of cut. The Parameter Space Investigation (PSI) method was used that allows research with minimal experience point quantity. It was found that turning with cooling conditions reduce both Ra and Rq values and intensities of cutting speed and feed rate influence as compared out under dry conditions. The use of low feed rate values has a positive effect of the Ra and Rq parameters.

ANALYSIS OF SURFACE TOPOGRAPHY OF SLIDE JOURNAL BEARINGS AND MICRO-BEARINGS

In this paper, the author presents the results of measurements of the slide journal bearings and micro-bearings sleeves and journal surfaces. The study was performed with the atomic force microscope (AFM) NT-206. The results of measurements of surface topography are presented in the form of a 2D and 3D map of surface topography and also in the form of profiles for selected cross-sections of examined surfaces. Additionally, the height distributions of surface roughness are presented. The Atomic Force Micsroscope NT-206 allows investigating the surface of sample with maximum scanning area 32Pm x 32Pm and with the maximum value of roughness ±1Pm. The measurements can be carried out in three modes: static (contact) mode, dynamic (non-contact) mode, dynamic intermittent mode. The author used the contact mode. The application of this mode of operation, in the case of samples with a hard surface, for example, the journal of a bearing, enables to obtain a good mapping of the measured surface. The presented in this paper results of surface topography measurements, include the calculated values of the Ra and Rq parameters and also the maximum value of the distance between the lowest and the highest surface inequality. The obtained results allow evaluating the amount and type of wear of researched elements in the micro-scale and they also are useful in the design of such surface layers of co-operating components, in order to obtain optimum tribological properties. When considering the impact of the surface roughness on the change of height of bearing gap, and consequently the change of flow and operating parameters, the information about average distribution of roughness value is required. With such measurements, it is possible to obtain these data. In the presented research the micro-bearings from personal computers hard drives, as well as classic bearings and sleeves, were investigated.

Alternative descriptions of roughness for cylinder liner production

The roughness of stratified surfaces such as cylinder liners, produced by plateau honing, is functionally important in their tribology but is notoriously difficult to characterise. An issue in manufacturing quality control related to their tribological function is the comparative ability of various roughness characterisation systems. In this paper the Rk family of parameters is compared with the Rq family as regards stability and discrimination. When coefficients of variation of the two parameter families are compared as a measure of stability, CVs of individual parameters vary between 8% and 20% but do not seem to indicate a clear advantage to either family. When the correlation of parameters within and between the two groups is computed as a measure of relative discriminative ability, many parameters are found to be highly correlated, to the point where values of Rpk and Rpq are effectively indistinguishable. The relative robustness of the parameters is also established by simulation of surface or measurement artefacts: outlying peaks and valleys, high-frequency noise, changes in stylus or skid radius, changes in high-pass filter and in assessment length. Outlying peaks cause a large increase in Rpk, while outlying valleys have little effect. The Rq parameters are more sensitive to high-frequency noise than the Rk parameters. Increasing the stylus radius reduced the valley parameters, while adding a 25 mm radius skid increased Rk and Rpq by as much as 15%. Increasing the short-wavelength cut-off from 2.5 μm to 8 μm reduced most parameters, particularly the peak parameters, while replacing the robust Gaussian filter used throughout by a valley-suppression filter had little effect. Finally reducing the assessment length from 17 mm to 4 mm decreased the values of many parameters by up to 11%. Increasing plateau honing time decreased plateau roughness, while increasing pressure during coarse honing increased valley roughness, but these changes could not be correlated with roughness parameters. This suggests that the optimum parameter set has not yet been found.