Rough Phase Research Articles

Efimov effect at the Kardar-Parisi-Zhang roughening transition.

Surface growth governed by the Kardar-Parisi-Zhang (KPZ) equation in dimensions higher than two undergoes a roughening transition from smooth to rough phases with increasing the nonlinearity. It is also known that the KPZ equation can be mapped onto quantum mechanics of attractive bosons with a contact interaction, where the roughening transition corresponds to a binding transition of two bosons with increasing the attraction. Such critical bosons in three dimensions actually exhibit the Efimov effect, where a three-boson coupling turns out to be relevant under the renormalization group so as to break the scale invariance down to a discrete one. On the basis of these facts linking the two distinct subjects in physics, we predict that the KPZ roughening transition in three dimensions shows either the discrete scale invariance or no intrinsic scale invariance.

Reconstructing algorithm for frequency-resolved optical gating based on intelligent seeker optimization

Frequency-resolved optical gating (FROG) is a common technique of ultrashort pulse measurement. It reconstructs the test pulse by an iterative two-dimensional phase retrieval algorithm from a FROG trace. Now the most widely used FROG algorithm is principal component generalized projection (PCGP), yet its accuracy of pulse retrieval drops obviously under noise condition, and its iterative speed slows down significantly as the size of FROG trace increases. Actually, most of ultrashort pulses delivered from ultrafast oscillators and amplifiers as well as created in most scientific experiments are of smooth spectral phases, so that they can be determined by a few of dispersion coefficients. In this paper, we propose a FROG algorithm based on seeker optimization algorithm (SOA). After recording the spectrum of the test pulse, several main dispersion coefficients of the spectral phase of the pulse are searched directly by the SOA algorithm to fit the corresponding FROG trace. Then the shape of the test pulse can be uniquely reconstructed. Since this algorithm mainly operates in a spectral domain and its routine of iteration is much simpler than PCGP’s, faster speed and higher accuracy of pulse retrieval can be expected. In order to prove the advantages of SOA-FROG algorithm, numeral simulations are performed for test pulses with varying dispersion, in the cases without noise and with 1%, 5%, 10%, 20% noise levels, respectively. The simulation results show that the new algorithm performs much better than PCGP in accuracy and iteration speed. In the case without noise, 97% test pulses reach the condition of rigid convergence (FROG error <i>G</i> ≤ 10<sup>–4</sup>) after 1500 iteration circles by using the SOA, with an average FROG error <i>G</i> < 10<sup>–5</sup>. So the accuracy of pulse reconstruction by SOA is at least three orders of magnitude higher than by PCGP. In cases with different noise levels, the accuracy of pulse reconstruction by SOA is also much higher than by PCGP. By means of background-subtraction and filtering on the FROG traces, the retrieved pulse profiles almost accord with reality. Typically for a 256 × 256 FROG trace, SOA-FROG iterates 100.8 circles per second, about 5 times faster than PCGP. After 300 iteration circles by SOA in about 3 s, most of test pulses can finish their routines of reconstruction and reach high accuracy. Besides SHG-FROG, the SOA-FROG algorithm can also be utilized in other FROG techniques based on the 3<sup>rd</sup> order nonlinear optical effects. In summary, the SOA-FROG is expected to be suitable to the real-time pulse measurement with high accuracy in most of application cases. Yet some measures of improvement should be taken to reconstruct complex pulses with rough spectral phases or/and broken spectra.

Alkyl side chain engineering for difluorinated benzothiadiazole flanked non-fullerene acceptors toward efficient polymer solar cells

Side chain engineering plays a vital role in fine tuning of non-fullerene acceptors for the contemporary organic solar cells. In this work, we compare central alkyl side chains in the modification of photophysical and photovoltaic properties of difluorinated benzothiadiazole flanked non-fullerene acceptors. With a hexyl side chain, the resulting non-fullerene H-FFBR possesses more compact intermolecular interaction, leading to narrower bandgap, higher-lying HOMO level and stronger self-aggregation, if compared to O-FFBR with octyl side chain. For the photovoltaic performances, with PTB7-Th as the donor polymer, the O-FFBR-based solar cells exhibit power conversion efficiency of 9.4%, which is higher than that of 9.1% for the H-FFBR-based devices. Bulk-heterojunction morphologies of the O-FFBR- and H-FFBR-based active layers were compared by atomic force microscopy (AFM) and transmission electron microscope (TEM), revealing that O-FFBR is likely to give lower surface roughness and smaller phase separation. Our work demonstrates that varying alkyl side chain of a non-fullerene acceptor is valuable to tune the bulk-heterojunction morphology and resulting photovoltaic performance.

Finite-size effects in the rough phase of the 3d Ising model

Using Monte Carlo simulations, finite-size effects of interfacial properties in the rough phase of the Ising on a cubic lattice with L×L×R sites are studied. In particular, magnetization profiles perpendicular to the flat interface of size L×R are studied, with L being considerably larger than R, in the (pre)critical temperature range. The resulting R-dependences are compared with predictions of the standard capillary-wave theory, in the Gaussian approximation, and with a field theory based on effective string actions, for L=∞.

Effect of Martensitic Transformation and Grain Size on the Surface Roughening Behavior in SUS 304 and SUS 316 Thin Metal Foils

The surface roughening and martensitic phase transformation (MPT) of SUS 304 and SUS 316 were studied through two experiments: a uniaxial tensile stress test, repeated for five cycles, and an Scanning Electron Microscope–Electron Backscaterr Diffraction (SEM-EBSD) investigation. The MPT and martensitic volume fraction (Mf) were evaluated following the tensile test. The correlation between MPT, Mf, and surface roughening behavior was investigated. The experiment showed that an increase in the strain level from 0.4% to 1% increased the MPT and Mf, which transformed from a metastable austenitic phase in SUS 304. The increased strain level increased the surface roughening for various grain sizes (Dg), from fine grain (Dg < 3 μm) to coarse grain (Dg ≥ 3 μm). SUS 304 and SUS 316 are used so that the surface roughening mechanism between SUS 304 and SUS 316, with different phase conditions and at a similar Dg, can be determined. The results showed that the surface roughening increased for both fine and coarse grain at strain levels of 0.4% and 1%; however, a larger increase of surface roughening was obtained for coarse grain. In coarse grain, surface roughening increased significantly not only with a low MPT, but also with a low grain deformation. In coarse grain, the surface roughening increased proportionally to the strain level (εp) because of the low MPT and weak grain. In fine grain, the surface roughening did not increase proportionally to the εp because of the high MPT, which increased the grain strength in SUS 304. In the fine grain of SUS 304, the increase of surface roughening was nearly the same both at strain levels of 0.4% and 1%, because the MPT and Mf were nearly the same. The surface roughening with the same εp and almost the same Dg in SUS 304 and SUS 316 fine grain was nearly the same, because the grain deformation almost produced the same relative inclination between neighboring grains in the initial state direction to the surface. The inter-grain movement changed the grain orientation. Based on kernel average misorientation (KAM) mapping, the local grain misorientation in SUS 304 was higher than that in SUS 316. This indicated that the fine-grain SUS 304 is harder than the fine-grain SUS 316. There is no MPT in SUS 316 because of the higher austenitic phase, which is affected by the austenitic former, such as Ni.

Lipopolysaccharide-Linked Enterobacterial Common Antigen (ECALPS) Occurs in Rough Strains of Escherichia coli R1, R2, and R4.

Enterobacterial common antigen (ECA) is a conserved surface antigen characteristic for Enterobacteriaceae. It is consisting of trisaccharide repeating unit, →3)-α-d-Fucp4NAc-(1→4)-β-d-ManpNAcA-(1→4)-α-d-GlcpNAc-(1→, where prevailing forms include ECA linked to phosphatidylglycerol (ECAPG) and cyclic ECA (ECACYC). Lipopolysaccharide (LPS)-associated form (ECALPS) has been proved to date only for rough Shigella sonnei phase II. Depending on the structure organization, ECA constitutes surface antigen (ECAPG and ECALPS) or maintains the outer membrane permeability barrier (ECACYC). The existence of LPS was hypothesized in the 1960–80s on the basis of serological observations. Only a few Escherichia coli strains (i.e., R1, R2, R3, R4, and K-12) have led to the generation of anti-ECA antibodies upon immunization, excluding ECAPG as an immunogen and conjecturing ECALPS as the only immunogenic form. Here, we presented a structural survey of ECALPS in E. coli R1, R2, R3, and R4 to correlate previous serological observations with the presence of ECALPS. The low yields of ECALPS were identified in the R1, R2, and R4 strains, where ECA occupied outer core residues of LPS that used to be substituted by O-specific polysaccharide in the case of smooth LPS. Previously published observations and hypotheses regarding the immunogenicity and biosynthesis of ECALPS were discussed and correlated with presented herein structural data.

Multiphase coexistence and enhanced piezoelectric properties in (1−x)(K0.45Na0.55)(Nb0.965Sb0.035)O3−xBi0.5(K0.91Li0.09)0.5(Hf0.3Zr0.7)O3 lead-free ceramics

A new lead-free piezoelectric solid solution system with the formula of (1−x)(K0.45Na0.55)(Nb0.965Sb0.035)O3−xBi0.5(K0.91Li0.09)0.5(Hf0.3Zr0.7)O3 were prepared using a conventional solid-phase sintering method, and we investigated the relationship between the composition, microstructure, phase structure and electrical properties of the ceramics. It was found that adding Bi0.5(K0.91Li0.09)0.5(Hf0.3Zr0.7)O3 induced the ceramics transition from a single orthorhombic structure to a coexistence of multiple phases, and a three-phase coexistence of rhombohedral, orthorhombic and tetragonal phases was present in the composition range x = 0.03 to 0.035. Enhanced piezoelectric properties were obtained for the ceramics near the three-phase coexistence region, with the largest piezoelectric constant d33 of 253 pC/N and the highest planar electromechanical coupling coefficient of 0.36. Additionally, a rough phase diagram for the solid solution system was established by using the critical temperatures determined by the temperature-dependent dielectric properties. The authors believe that these results can provide a useful reference for the development of (K,Na)NbO3-based lead-free piezoelectric ceramics.

Miniaturization, Triple-Line Effects, and Reactive Wetting of Microsolder Interfaces.

While reactive microsolder joints are of ubiquitous importance in modern electronics, the effects of joint miniaturization on wetting behavior remain largely unexplored. We elucidate this fundamental question of scalability by investigating the wettability of eutectic SnPb solder on Cu and Ni-electrodeposited metallization strips of varying widths. Contact angles are presented in dependence of the metallization width which is varied from 3 mm down to ∼100 μm. The measured angles clearly increase with decreasing metallization width. Based on the measurements and by modifying Young's equation, it is shown that the behavior of the wetting angle can be quantitatively understood with an "effective" triple-line energy of ϵt = (753 ± 31) × 10-9J/m for SnPb on Cu. The interpretation of this energy term is discussed in relation to the forming intermetallic phase and the ensuing surface roughness. A remarkable similarity between the experimentally observed size dependence and the crossed-groove perturbation model of Huh and Mason demonstrates that the rough intermetallic phase induces wetting hysteresis such that it is quantitatively well described by an effective triple-line energy.

Effects of combining ultrasonic micro-forging treatment with laser metal wire deposition on microstructural and mechanical properties in Ti–6Al–4V alloy

Ultrasonic micro-forging treatment (UMFT) is a novel grain refinement and properties improvement technique based on plastic deformation and ultrasonic vibration, and it can be applied to the manufacture of large components. The effects of the different amplitudes and loads of UMFT on microstructure and mechanical properties of laser metal wire deposition (LMwD) Ti–6Al–4V alloy were researched in this paper. The microstructural evolution and properties improvement were investigated by means of optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, surface roughness tester, vickers hardness tester and nano indentor. Experimental results showed that amplitudes and loads can significantly affect geometric dimensioning, surface roughness and constituent phases of the deposited layers. The microstructure of un-treated sample consists of epitaxial growth columnar β grains and a certain volume fraction of equiaxed β grains. A large volume fraction of equiaxed β grains appeared in UMFTed samples and the area percentage of equiaxed grain can be controlled by deposition parameters. The evolution of grain morphology should be attributed to recrystallization. Moreover, after UMFT, vickers hardness increased from 360 HV to 520 HV, nano hardness increased by 1.54 times and Young's modulus reached to 170 GPa. The increase of hardness and Young's modulus are likely to be caused by grain refinement.

Influence of alumina air-abrasion for highly translucent partially stabilized zirconia on flexural strength, surface properties, and bond strength of resin cement.

Objective This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ.Methodology Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests.Results The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging.Conclusion Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.

An active reconstruction algorithm based on partial prior information

Active reconstruction is an intelligent perception method that achieves object modeling with few views and short motion paths by systematically adjusting the parameters of the camera while ensuring model integrity. Part of the object information is always known for vision tasks in real scenes, and it provides some guidance for the view planning. A two-step active reconstruction algorithm based on partial prior information is presented, which includes rough shape estimation phase and complete object reconstruction phase, and both of them introduce the concept of active vision. An information expression method is proposed that can be used to manually initialize the repository according to specific visual tasks, and then the prior information and detected information are used to plan the next best view online until the object reconstruction is completed. The method is evaluated with simulated experiments and the result is compared with other methods.

Surface characterization of monolithic zirconia submitted to different surface treatments applying optical interferometry and raman spectrometry.

This study evaluated roughness parameters and phase transformation of monolithic zirconia ceramics after various mechanical and laser thermal treatments. Fully sintered monolithic zirconia cylinder specimens were divided to five groups, according to the applied surface treatment: CL: control, GB: grit-blasted with glass particles. AL50: grit-blasted with 50 μm alumina particles, AL90: grit-blasted with 90 μm dyed-alumina particles and FEML: subjected to femto laser thermal treatment. Six roughness parameters (Sa, Sq, Sz, Sci, Svi and Sdr) were measured by optical profilometry. Phase transformation in zirconia was determined by micro-Raman spectroscopy. The highest roughness values were recorded in AL90 and FEML groups, followed by AL50. AL90 presented statistically higher monoclinic phase content compared to all other groups. Control and GB groups presented similar roughness without phase transformation. Laser thermal treatment causes minimal destruction of the zirconia surface, and can be suggested as an alternative to other roughening treratments, for enhancing the adhesive potential to dentin.

Variable Phase and Electrochemical Capacitance of Electrospun MnOx Fibers Via Controlled Calcination

ABSTRACTSupercapacitors have the potential to complement or replace batteries in many current and emerging applications. As inexpensive and environmentally benign capacitive materials, manganese oxides are promising electrode materials. Nanostructured oxides have high energy storage capacities owing to their increased surface-area-to-volume ratios as compared to bulk materials. By electrospinning precursor-containing polymer fibers and subsequently calcining, nanostructured MnOx fibers can be prepared with relative ease. Controlling calcination pressure and time provides a route for variable capacitance via modifying surface roughness and oxide phase. At moderate pressures and short calcination times, mixed-phase Mn2O3/Mn3O4 fibers with high surface roughness exhibit enhanced electrochemical specific capacitance.

Spectral Gap Critical Exponent for Glauber Dynamics of Hierarchical Spin Models

We develop a renormalisation group approach to deriving the asymptotics of the spectral gap of the generator of Glauber type dynamics of spin systems with strong correlations (at and near a critical point). In our approach, we derive a spectral gap inequality for the measure recursively in terms of spectral gap inequalities for a sequence of renormalised measures. We apply our method to hierarchical versions of the 4-dimensional n-component |varphi |^4 model at the critical point and its approach from the high temperature side, and of the 2-dimensional Sine-Gordon and the Discrete Gaussian models in the rough phase (Kosterlitz–Thouless phase). For these models, we show that the spectral gap decays polynomially like the spectral gap of the dynamics of a free field (with a logarithmic correction for the |varphi |^4 model), the scaling limit of these models in equilibrium.

Phase-shifting profilometry for the robust 3-D shape measurement of moving objects

Arbitrary two-dimensional (2-D) motion introduces coordinate errors and phase errors to three-dimensional (3-D) shape measurement of objects in phase-shifting profilometry (PSP). This paper presents a new robust 3-D reconstruction method for arbitrary 2-D moving objects by introducing an adaptive reference phase map and the motion estimation based on fence image. First, a composite fence image is used to track object motion. Second, to obtain the transformation matrixes and remove the coordinate errors among object images, the angle extraction technique and the 1-D hybrid phase correlation method (1-D HPCM) are integrated to automatically estimate the sub-pixel motion of objects. Third, the phase errors are compensated to obtain the rough absolute phase map of objects by combining the transformation matrixes with the reference phase map. Finally, the absolute phase map is refined to reconstruct the 3-D surfaces of moving objects with adaptive reference phase map. The proposed computational framework can accurately and automatically realize 3-D shape measurement of arbitrary objects with 2-D movement. The results of experiment verify the effectiveness of our computational framework.

Antiferroelectric thick film grown on metal foils with fast discharge speed and excellent energy-storage properties

Antiferroelectric (AFE) Pb0.94La0.04Zr0.97Ti0.03O3 (PLZT) thick film was successfully fabricated on nickel foils by using sol–gel method. The film exhibits dense microstructure with low surface roughness and pure perovskite phase. It displays high dielectric constant of 433 at 100 kHz and room temperature, which is 28% larger than that on traditional silicon substrate. Calculated by polarization-field (P–E) hysteresis loop, the recoverable energy-storage density (Wrec) of 18.4 J/cm3 and the efficiency (Ƞ) value of 54% at 1400 kV/cm are obtained in the thick film. Measured by resistance–inductance–capacitance (RLC) circuit, the maximum pulsed discharge energy-storage density (Wdis) of 12.4 J/cm3 is found at the same electric field of 1400 kV/cm. Moreover, 90% of the energy is released in a short time of about 84 ns, displaying super-fast discharging characteristic. The AFE film with high discharge energy-storage density and fast discharge time provides strong potential for the application in modern electronics and electrical power systems.

Parametrix for wave equations on a rough background III : space-time regularity of the phase

This is the third of a sequence of four papers \cite{param1}, \cite{param2}, \cite{param3}, \cite{param4} dedicated to the construction and the control of a parametrix to the homogeneous wave equation $\square_{\bf g} \phi=0$, where ${\bf g}$ is a rough metric satisfying the Einstein vacuum equations. Controlling such a parametrix as well as its error term when one only assumes $L^2$ bounds on the curvature tensor ${\bf R}$ of ${\bf g}$ is a major step of the proof of the bounded $L^2$ curvature conjecture proposed in \cite{Kl:2000}, and solved by S. Klainerman, I. Rodnianski and the author in \cite{boundedl2}. On a more general level, this sequence of papers deals with the control of the eikonal equation on a rough background, and with the derivation of $L^2$ bounds for Fourier integral operators on manifolds with rough phases and symbols, and as such is also of independent interest.

Enamel wear and aging of translucent zirconias: In vitro and clinical studies

Statement of problemZirconia is a widely used restorative material. However, phase transformation on clinical application of zirconia has not yet been studied. PurposeThe purpose of this study was to evaluate the wear, surface roughness, and aging associated with polished translucent zirconia in both in vitro and clinical experiments. Material and methodsIn vitro experiments were performed with Rainbow and Katana zirconia blocks and natural tooth enamel as the control. They were subjected to 100 000 loading cycles with a maxillary premolar antagonist. All specimens were analyzed for wear, and the zirconia specimens were evaluated for surface roughness and monoclinic phase (m-phase) transformation by X-ray diffractometry before and after cyclic loading. The clinical study included participants who required single-crown implant-supported restorations replacing the first or second molar. The participants received Rainbow or Katana zirconia prostheses (n=15, each). For wear analysis, impressions of each prosthesis, antagonist, and adjacent tooth were made at 1 week and 6 months after crown delivery. The occlusal relationship of the crowns in maximum intercuspation was evaluated by using the T-Scan 8 occlusal diagnostic system. The degree of transformation of zirconia to the m-phase was measured by using X-ray diffractometry of the crowns after 6 months of use. ResultsZirconia induced significantly greater enamel wear than the natural tooth control. Katana specimens exhibited significantly greater wear and surface roughness than the Rainbow specimens. The degrees of antagonistic wear and zirconia phase transformation in the clinical experiment were significantly greater than those in the in vitro experiment. The Katana groups showed significantly higher m-phase levels than the Rainbow groups. ConclusionsPhase transformation of zirconia occurs within 6 months of clinical use, and the wear and degrees of phase transformation varied according to the zirconia product used.

Transference of local to global L2 maximal estimates for dispersive partial differential equations

In this paper we give an elementary proof for transference of local to global maximal estimates for dispersive PDEs. This is done by transferring local L 2 estimates for certain oscillatory integrals with rough phase functions, to the corresponding global estimates. The elementary feature of our approach is that it entirely avoids the use of the wave packet techniques which are quite common in this context, and instead is based on scalings and classical oscillatory integral estimates.

Effect of Flame Spray Deposition Parameters on The Microstructure of Al2 O3 - 13 %TiO2 Coatings Applied Onto 7075 Aluminum Alloy

In this work, the effect of flame spraying parameters on physical, structural and microstructural characteristics of Al2O3 - 13 wt.% TiO2 (AT-13) coatings were studied. NiCrAl and AT-13 feedstock powders were used for spraying a bond coat (BC) and a top coat (TC), respectively, onto a 7075 aluminum alloy substrate. The effect of acetylene-to-oxygen ratio and the spraying distance on surface roughness, crystalline phases, porosity and thickness of top coat were analyzed. The results showed that for the evaluated spraying conditions, the volumetric oxy-fuel ratio had significant effects on roughness, porosity and crystalline phases of the coating. On the other hand, the spraying distance affected the thickness of the coating and did not influence the formation of Al2TiO5 phase; no significant effect of spraying distance on roughness was observed. The results showed that an acetylene: oxygen volumetric ratio of 1:2.5 is preferable to obtain higher melting of the ceramic powders and therefore a denser coating with major content of γ-Al2O3 crystalline phase.