Rough Correlation Research Articles

Surface morphology and drug loading characterization of 3D-printed methacrylate-based polymer facilitated by supercritical carbon dioxide

Polymers have been shown to have viable applications in the biomedical field, from controlled drug delivery systems to biological implants. The preparation and processing of polymers into bio-systems have nevertheless encountered some technical challenges in part customization and adverse effects to the human body functions and recovery. This study proposes the utilization of 3D printing technology and supercritical carbon dioxide (scCO2) processing to deliver a drug-impregnated polymeric material system which can be engineered and tuned to suit a particular implantation procedure and dramatically improve patient outcomes. In this work, an acrylate-based polymer is 3D-printed using stereolithography, then impregnated with flurbiprofen drug using scCO2. Drug loading above 24 % by mass is achievable under the tested conditions. The correlation of drug loading and material surface roughness with different process parameters, including 3D printing layer thickness, scCO2 processing temperature, pressure and treatment time, are investigated and empirically modeled using the linear regression methods.

Matt Polyurethane Coating: Correlation of Surface Roughness on Measurement Length and Gloss.

Matt polyurethane coating was successfully prepared through the synergistic effect of castor oil and phenolic epoxy resin into polyurethane backbone. The formation mechanism may be ascribed to the modulus mismatch between the partially modified epoxy polyurethane and partially unmodified polyurethane. Scanning electron microscopy (SEM) was used to observe the micro-rough surface morphologies. Atomic force microscopy (AFM) and three-dimensional (3D) surface profilometer were applied to calculate a series of surface roughness parameters in different dimensions, such as Sa, Sq, Sp, Sv, Sz, Sku, Ssk, etc. The exciting results of this paper—the correlation of surface roughness on measurement length and gloss—are explored in detail. It reveals the extrinsic property of measured roughness with measurement length and provides guidance for what kind of incident angle gloss meters (20°, 60°, and 85°) best describe the gloss of matt polyurethane coating.

Analysis and prediction of TBM disc cutter wear when tunneling in hard rock strata: A case study of a metro tunnel excavation in Shenzhen, China

Disc cutter wear is the result of dynamic contact and friction between the tools and rocks in tunnel boring machine (TBM) tunneling. It can lead to a reduction in excavation efficiency, disruption of construction schedules, and extra costs. The geological indices, such as uniaxial compressive strength (UCS), Brazilian tensile strength (BTS) and Cerchar abrasion index (CAI), and the tunneling parameters, such as advance rate and rotation speed, were collected in the Shenzhen metro tunnel excavation project, and they have major effects on the cutter consumption rate. The wear data of 871 disc cutters over a 1592 m-long advance distance were analyzed. It was found that 87% of the disc cutters used were replaced due to normal wear, and the others were replaced due to abnormal wear. Flat wear mainly occurs for the disc cutters in the central area of the cutterhead, because they have a larger rotational resistance and eccentric loading due to their smaller rotational radius. The abnormal wear of the outer-area disc cutters mainly consists of forms of cutter ring cracking and bearing crushing owing to a higher rotation speed. A disc cutter wear prediction model was established to estimate the disc cutter consumption based on the plastic removal abrasiveness and motion analysis of the cutter rings. A rough linear correlation between the cumulative wear depth and the advance distance is found, and the wear rate varies during the tunneling progress due to the different geotechnical or construction parameters. The predicted wear is generally less than the actual wear, and the maximum prediction error is 49.4 mm. The predicted error is always larger for the disc cutters that have a high probability of non-uniform wear, especially for those in the outer area.

A New Method of Roughness Construction and Analysis of Construct Parameters

In micro-manufacturing, roughness is unavoidable due to the tolerance of micro-machining methods. Roughness in microchannel could have a significant influence on flow and heat transfer since the size of microchannel is very small. In our work, roughness is modeled as a superposition of waves. A simple Fourier series method is proposed to construct the rough surface. With this method, roughness is constructed on the bottom of the rectangular microchannel which has a hydraulic diameter of 0.5 mm. Two important parameters during roughness construction, triangulate size and correlation length are studied under the same relative roughness 1%. Results show that flow and heat transfer characteristics are not sensitive to triangulate size. While triangulate size is changing from 0.1 mm to 0.05 mm, the variations of pressure drop and average Nusselt number are less than 1%. Correlation length could influence the topography of roughness surface a lot, smaller correlation length will lead to more pressure drop and lower Nusselt number.

Three-dimensional line edge roughness in pre- and post-dry etch line and space patterns of block copolymer lithography.

In this work, we employ large-scale coarse-grained molecular dynamics (CGMD) simulations to study the three-dimensional line edge roughness associated with line and space patterns of chemo-epitaxially directed symmetric block copolymers (BCPs) on a flat substrate. The di-block copolymer chain length and interaction parameters are validated with the experimental BCP period, L0 and corresponding molecular weight. Defect-free lamellae are formed, after which the system is quenched below the glass transition temperature before selectively dry-etching off one of the BCP phases. The effect of varying etch-selectivity on post-etch resist domain morphology was studied. The roughness of the polymer domain was evaluated over three process stages: annealing, pre-etching, and post-etching. Power spectral density plots were then generated to elucidate the contributions of low and high frequency roughness for the three process stages. The roughness results obtained from simulations are shown to be in close agreement with the roughness result obtained from analyzing experimental SEM images. Parameters like the Hurtz roughness exponent and correlation length inherent to the process and the BCP were also revealed from the experimental study.

Surface-roughness measurement based on scalar field correlation with active millimeter-wave imaging system.

Active millimeter-wave (MMW) imaging is of interest because it has played an important role in the area of personnel surveillance over the past decades. Through reconstructing reflectivity, potential threats can be recognized based on shape. Besides reflectivity, diverse physical characteristics should be explored so that supplementary information can be used to assist recognition. This paper presents a surface-roughness measurement method using holographic data that has already been acquired during security checks. Based on scalar diffraction theory and speckle metrology, a simple mathematical relation between the correlation of holographic fields and surface roughness has been derived. Consequently, another kind of information, that is, the surface-roughness estimate, can be used to help differentiate similarly shaped articles. Results of simulations and laboratory experiments have shown its validation and potential in application to MMW imaging systems.

A correlation of metallic surface roughness with its hydrophobicity for dropwise condensation

Abstract The surface morphology alike lotus leaf has high contact angle and low contact angle hysteresis with respect to water droplet because of nanoscale roughness superimposed on micro order roughness in well-organized manner. The major application of superhydrophobic metallic substrate is in the condensing unit of energy and water harvesting devices. In this work, nanoscale roughness is superimposed on micro-order roughness of Aluminum substrate. The chemical texturing method is used to create micro-scale roughness onto Al surface. However, 0.6 keV Ar ions are irradiated for various time span to fabricate nano order roughness on chemically etched substrate. The roughness of samples is measured by Atomic Force Microscopy and static contact angles and their hysteresis are measured by lab customize Goniometer. It is found that the static contact angle and contact angle hysteresis increases after irradiation on chemical etched surfaces. Multi-scale roughness is observed on irradiated substrate. Results also shows that contact angle increases with increasing time of irradiation. However, maximum change in static contact angle is observed for samples irradiated for 45 s. Eventually, the static contact angle is correlated with its surface roughness. This correlation is vital for optimizing parameter affecting condensation rate in dropwise condensation. Finally, the moist air condensation experiments are conducted to know the condensation efficacy of the irradiated substrate. Also, it is found that the drop sliding frequency on vertical irradiated Al substrate is higher than the chemical etched Al substrate.

Roughness and amorphization impact on thermal conductivity of nanofilms and nanowires: Making atomistic modeling more realistic

In this work, the impact of roughness and amorphization on the effective thermal conductivity of silicon nanofilms and nanowires is studied with atomistic simulations. The discrepancy between simulations and experimental measurements shows that it is necessary to consider realistic roughness and amorphization to reach an agreement. We show that subnanometric roughness and specific correlation length can reduce thermal transport by a factor of two in both nanofilms and nanowires; in addition, this reduction is even more pronounced than the one related to the existence of native oxides or amorphous phases on nanostructure edges. Furthermore, an interfacial thermal resistance parallel to the heat flux is observed. This thermal resistance is increasing upon the increase of the amorphous shell thickness, reaching a maximum value for thickness of 6 nm. Our findings could improve the strategy to elaborate nanomaterials with enhanced thermoelectric efficiency by tuning thermal conductivity through the engineering of surfaces.

Black silicon – correlation between microstructure and Raman scattering

Abstract Black silicon layers were formed on silicon substrate by the surface structure chemical transfer method and by anodic etching method. Properties of microstructure of formed layers were experimentally studied by the electron microscopy methods (TEM) and characterized by statistical, Fourier and multifractal methods. Theoretical structures with defined fractal properties and surface roughness were generated and their microstructure properties were evaluated. Obtained results were used for the explanation of the real structure development during the forming procedure. By using of this approach, we study the correlation of roughness and fractality with optical properties. Black silicon layers were also investigated by using of Raman scattering method. Optimized theoretical model describing the 1st order of black Si Raman scattering profile was constructed and used for evaluation of the biaxial tensile stress introduced during etching procedure.

Correlation of surface roughness, tool wear, and chip slenderness ratio in the lathe process of aluminum alloy – 6061

The research on the lathe process has described that the tool nose radius parameter is one of the factors that has an influence on surface roughness in the form of product quality. Chip slenderness ratio is an important parameter in the lathe process that can be applied theoretically or empirically. The lathe process was carried out on the Aluminum Alloy – 6061 material, the effects of the selected responses, namely surface roughness (SR), surface area of tool wear (Vb), and chip slenderness ratio (δ) were investigated. The selection of the main cutting tool nose radius (ns), spindle speed (n), feeding speed (vf), and depth of cut (a) can affect surface roughness which were conditioned to be constant, can influence chip shape and chip slenderness ratio and surface area of tool flank wear. The chip shape in the lathe process has a correlation with the product surface roughness, the chip slenderness ratio, and the tool flank wear. In this study, the experimental investigation and statistical analysis used the Taguchi experimental design method of L9 (34) orthogonal array, and the parameters used in the lathe cutting process of Aluminum Alloy – 6061 were tool angle, spindle speed, depth of cut and feed rate that affected the response results ((SR), (δ), and Vb). The contribution of each factor to the output is determined by variance analysis. Using ANOVA, the multiregression model is obtained by the relationship between the factors (ns, n, vf, and a) on the response (SR, δ, and Vb), expressed by the following equation: SR=0.955556+0.074444ns+0.006667n+0.005556vf–0.001111a, δ=7.18889–1.17556ns–0.59222n–0.60222vf–0.09111a, and Vb=0.320370–0.073704ns–0.021481n–0.041481vf–0.032593a. Correlation results found that: (a) tool nose radius of 0.4 mm, feeding speed 56 mm/min, and cutting depth of 0.25 mm had an influence on SR=1.11 µm, (b) tool nose radius of 1.2 mm, feeding speed 58 mm/min and the depth of cut of 0.25 mm have an influence on δ=7.07, (c) tool nose radius of 0.4 mm, feeding speed of 60 mm/min, and cutting depth of 0.50 mm have an influence on Vb=0.34 mm2. The conclusion is that the effect on the correlation of the R2 value is very strong against SR=97.89 %, δ=94.45 % and Vb=67.30 %

Surface Morphology of Silicon Waveguide after Reactive Ion Etching (RIE)

The side wall profile roughness of the silicon waveguide prepared by electron beam lithography and reactive ion etching is extracted by using the boundary tracing method. The maximum, minimum, and average roughness values are extracted from the side wall boundary, and the changes of the side wall boundary of waveguide after electron beam exposure and reactive ion etching were compared. The roughness variation of the waveguide side wall is similar with the same length. And roughness from the bottom of the waveguide etched region is measured directly by laser confocal microscope and roughness correlation statistics are also obtained.

Quantitative Study of the Geometrical and Hydraulic Characteristics of a Single Rock Fracture

Three-dimensional images of fractured rocks can be acquired by an X-ray micro-CT scanning technique, which allows researchers to investigate the ‘true’ inner void structure of a natural fracture without destroying the core. The 3D fractures in images can be characterised by measuring morphological properties on both fracture apertures and its trend surface, like the medial surface, that reveals the undulation of fracture planes. In a previous paper, we have proposed a novel method to generate fracture models stochastically. Based on a large number of such fracture models, in this work a modified factor was proposed for improving the performance of the cubic law by incorporating the flow-dominant characteristics, including two parameters (aperture roughness and spatial correlation length) for fracture apertures and two (surface undulation coefficient and spatial correlation length) for fracture trend-surface. We assess and validate the modified cubic law by applying it to natural fractures in images that have varying apertures and extremely bended trend-surfaces, with the permeabilities calculated by a Lattice Boltzmann Method as ‘ground truths’.

Relationships between NMR shifts and interaction energies in biphenyls, alkanes, aza-alkanes, and oxa-alkanes with X─H… H─Y and X─H… Z (X, Y = C or N; Z = N or O) hydrogen bonding.

Hydrogen-hydrogen C─H… H─C bonding between the bay-area hydrogens in biphenyls, and more generally in congested alkanes, very strained polycyclic alkanes, and cis-2-butene, has been investigated by calculation of proton nuclear magnetic resonance (NMR) shifts and atom-atom interaction energies. Computed NMR shifts for all protons in the biphenyl derivatives correlate very well with experimental data, with zero intercept, unit slope, and a root mean square deviation of 0.06ppm. For some congested alkanes, there is generally good agreement between computed values for a selected conformer and the experimental data, when it is available. In both cases, the shift of a given proton or pair of protons tends to increase with the corresponding interaction energy. Computed NMR shift differences for methylene protons in polycyclic alkanes, where one is involved in a very short contact ("in") and the other is not ("out"), show a rough correlation with the corresponding C─H… H─C exchange energies. The "in" and "in,in" isomers of selected aza- and diaza-cycloalkanes, respectively, are X─H… H─N hydrogen bonded, whereas the "out" and "in,out" isomers display X─H… N hydrogen bonds (X = C or N). Oxa-alkanes and the "in" isomers of aza-oxa-alkanes are X─H… O hydrogen bonded. There is a very good general correlation, including both N─H… H─Y (Y = C or N) and N─H… Z (Z = N or O) interactions, for NH proton shifts against the exchange energy. For "in" CH protons, the data for the different C─H… H─Y and C─H… Z interactions are much more dispersed and the overall shift/exchange energy correlation is less satisfactory.

Entropy generation and exergy destruction in condensing steam flow through turbine blade with surface roughness

In the steam turbine, the wetness loss due to vapor condensation is one of the most crucial losses at low-pressure stage. This study focused on entropy generation and exergy destruction of condensing steam flow in turbine blade with the roughness. The governing equations including entropy transport equation combined with condensation model, transition SST model and roughness correlation were established and verified by experiments and theory. Flow field behaviors, such as wetness fraction, intermittency and turbulent viscosity distributions, controlled by the deviation angle were obtained to evaluate effects of back pressure ratio and surface roughness. The mass-averaged wetness fraction at outlet was also extracted considering the influence of uneven mass flux. Finally, each part of entropy generation derived from viscous, heat conduction, phase change and aerodynamic losses and exergy destruction ratio were analyzed. Research shows that roughness plays an important part in the intermittency and turbulent viscosity. The mass-averaged wetness fraction at outlet sharply drops with back pressure ratio but slightly decreases with the roughness. With the roughness rising or back pressure dropping, the entropy generation grows resulting in more exergy destruction. The maximum value of the total entropy generation is 84.520 J·kg−1·K−1, corresponding exergy destruction is 25.187 kJ·kg−1 and exergy destruction ratio is 4.43%.

Influence of Freestream Temperature on Ice Accretion Roughness

<div class="section abstract"><div class="htmlview paragraph">The influence of freestream static temperature on roughness temporal evolution and spatial variation was investigated in the Icing Research Tunnel (IRT) at NASA Glenn Research Center. A 53.34 cm (21-in.) NACA 0012 airfoil model and a 152.4 cm (60-in.) HAARP-II business jet airfoil model were exposed to Appendix C clouds for fixed exposure times and thus fixed ice accumulation parameter. For the base conditions, the static temperature was varied to produce different stagnation point freezing fractions. The resulting ice shapes were then scanned using a ROMER Absolute Arm system and analyzed using the self-organizing map approach of McClain and Kreeger. The ice accretion prediction program LEWICE was further used to aid in interrogations of the ice accretion point clouds by using the predicted surface variations of local collection efficiency. The resulting equivalent sand-grain roughness heights predicted using the correlation of Flack and Schultz are compared to the roughness correlation employed in LEWICE for roughness convection enhancement predictions. The results demonstrate the influence of the stagnation point freezing fraction on the maximum sand-grain roughness height. A new function is developed to predict the maximum sand-grain roughness height based on the stagnation point freezing fraction and accumulation time.</div></div>

Molecular insights into the carbon dioxide–carboxylate anion interactions and implications for carbon capture

In this work, we analyze the interaction of carbon dioxide with different carboxylate anion derivatives in the gas phase at the ab initio CCSD(T)//MP2 level using the aug-cc-pVTZ basis set. The systems considered here include the formate, acetate, propionate, bicarbonate, carbamate and glycinate anions. The study is relevant to get a better understanding of the interactions involved in novel carbon capture processes through either ionic liquids or amino acid salts. We describe the formation of covalent and non-covalent adducts and show that the formation energies are significantly larger than those previously reported for amines, which are used in conventional carbon capture processes. The nature of the interactions is analyzed using the natural bond orbitals methodology. The binding energy in the non-covalent processes does not depend much on the derivative, but covalent adducts display a rough correlation with nucleophilic/electrophilic indices provided distortion effects on the monomers are taken into account. In the case of glycinate, interactions with the amino and carboxylic moieties involve comparable energetics and the existence of several minima in the potential energy surface might be a factor contributing to the good CO2 capture capacity exhibited by this species in recent experimental studies.

Genomic architecture differences at the HTT locus associated with symptomatic and pre-symptomatic cases of Huntington’s disease in a pilot study.

Background:Huntington’s disease (HD) is a progressive neurodegenerative condition that causes degeneration of neurons in the brain, ultimately leading to death. The root cause of HD is an expanded trinucleotide cytosine-adenine-guanine (CAG) repeat in the “huntingtin gene” (HTT). While there is a rough correlation between the number of CAG repeats and disease onset, the development of clinical symptoms can vary by decades within individuals and little is known about this pre-symptomatic phase.Methods:Using peripheral blood samples from HD patients and healthy controls we usedEpiSwitch™, a validated high-resolution industrial platform for the detection of chromosome conformations, to assess chromatin architecture in the immediate vicinity of theHTTgene. We evaluated chromatin conformations at 20 sites across 225 kb of theHTTlocus in a small cohort of healthy controls, verified symptomatic HD patients (CAG, n>39) and patients with CAG expansions who had not yet manifested clinical symptoms of HD.Results:Discrete chromosome conformations were observed across the patient groups. We found two constitutive interactions (occurring in all patient groups) and seven conditional interactions which were present in HD, but not in healthy controls. Most important, we observed three conditional interactions that were present only in HD patients manifesting clinical symptoms (symptomatic cases), but not in presymptomatic cases. Of the patients in the symptomatic HD cohort, 86% (6 out of 7) demonstrated at least one of the specific chromosome conformations associated with symptomatic HD.Conclusion:Our results provide the first evidence that chromatin architecture at theHTTlocus is systemically altered in patients with HD, with conditional differences between clinical stages. Given the high clinical need in having a molecular tool to assess disease progression in HD, these results strongly suggest that the non-invasive assessment of chromosome conformation signatures warrant further study as a prognostic tool in HD.

Correlation analysis of the roughness as function of cutting speed and feed rate (the roughness as function of machining parameters)

Experimental evaluations based on statistical and scientific criteria play fundamental role in identification of optimal performance parameters in manufacturing engineering. Based on this premise, the Doehlert’s experimental planning method was applied to external cylindrical turning process of ABNT 1045 steel, with the purpose of determining the roughness correlation as a function of the cutting speed (Vc) and feed rate (f). The Doehlert’s matrix was defined with five levels for feed rate and three levels for cutting speed, according to coded variables. From these experiments the correlation between input and output variables was determined. The best model is in agreement with the analysis of variance and Fischer’s test. Graphs were obtained for both response and contour surfaces. In addition, the optimal point for the best model was determined by the Lagrange criterion, which corresponds to a feed rate (f) of 0.0880 mm rev-1 and the cutting speed (Vc) of 155 mm min.-1, resulting in a minimum roughness average value (Ra) equals to 0.8916 μm.

Uniaxial magnetic anisotropy in three-bilayer Co/Cu and Co/Al superlattices

We present the magnetic properties of three-bilayer superlattices [Co(0.8 nm)/Cu(1.1 nm)]3 and Co(0.8 nm)/Al(2.2 nm)]3 grown by magnetron sputter deposition on SiO2 substrates. Using the surface magneto-optical Kerr effect we observed longitudinal magnetic hysteresis loops with low coercivity values of <17 × 10−4 T and <7 × 10−4 T from Co/Cu and Co/Al superlattices, respectively. From the hysteresis loops as a function of in-plane azimuthal angle of the Co/Cu and Co/Al superlattices, we observed an in-plane uniaxial anisotropy in coercivity and squareness. Using a four-point square configuration we observed positive and negative anisotropic magnetoresistances (AMR) with values +0.5% and −0.5% from Co/Cu superlattice depending on whether the applied current is perpendicular or parallel to the applied magnetic field direction, respectively. The surface morphology including vertical root-mean-square roughness and lateral correlation length were examined by atomic force microscopy. The number of bilayers and the thicknesses of Co, Cu and Al in the superlattices were examined by X-ray reflectivity. The observed magnetic properties were correlated to the interface roughness and layer thickness. The low coercivity, low saturation field, near-one squareness, and finite MR value of the three-bilayer Co/Cu superlattice has potential applications in low magnetic field detection and sensors.

Two-Dimensional and Three-Dimensional Echocardiographic Assessment of Aortic Root Diameter in Patients with Coronary Ectasia

Background: Coronary artery ectasia (CAE) is a well-recognized but relatively uncommon finding encountered during diagnostic coronary angiography. It is commonly defined as in appropriate dilation of the coronary arteries exceeding the largest diameter of an adjacent normal vessel more than 1.5-fold. CAE is not an isolated and benign disease but a reflection of a generalized vascular media defect. Objective: The aim of this study was to compare 2D-TTEand 3D-TTE measurements of the aortic root diameter in patients with coronary artery ectasia to assess the presence of aortic root dilatation. Patients and methods: This prospective observational study included 50 consecutive patients came to the Department of Cardiology, Al-Azhar University Hospital, New Damietta for coronary angiography. The study was carried out from November 2017 until December 2018. Injection aortography was used as a gold standard and to assess the presence of ascending aorta dilatation in those patients. Results: The present study shows that there was a good correlation between 3D-TTE and aortography at the levels of aortic annulus, sinuses of Valsalva, sinotubular junction (r =0.98,0.95,0.98) but a rough correlation between 2D-TTE and aortography at these levels (r =0.49,0.48,0.46). The present study shows that there was increase prevalence of aortic root dilatation 13 patients (26%) and ascending aorta dilatation 9patients(18%) in patients with CAE. Conclusions: Accuracy of aortic root measurement by 3DTTE was superior to that by 2DTTE, because the values by 2DTTE were underestimated compared to those measured by 3DTTE and aortography. Increase prevalence of aortic root dilatation and ascending aorta dilatation in patients with coronary artery ectasia. Dilated Ascending aorta was associated with a higher prevalence of aortic root dilatation.