Longitudinal Surface Research Articles

Numerical study on the vapor bubble removal by acoustic streaming in downward-facing pool boiling

The dynamic mechanism of vapor bubble removal by acoustic streaming on downward-facing heating surface during boiling process was numerically investigated. It is observed that under the excitation of longitudinal surface acoustic wave (SAW), vortices are formed at the root of bubble due to acoustic streaming. The vortices promote the bubble to detach from heating surface, while inhibiting the lateral growth and movement of the bubble. Thus, the bubble can be suspended in the liquid, almost statically. In addition, under the excitation of the transverse SAW, the generated vortices produce a translational thrust on the bubble, causing the bubble to move laterally and eventually leave the heating surface. For the case of superimposed SAWs excitation, the transverse SAW breaks the balance of vortical flow around the bubble which initially excited by the longitudinal SAW. Meanwhile, the unbalanced vortices destroy the boundary layer of heating surface, and weaken the influence of the viscous force as well. The results show that under the superimposed SAWs excitation, comparing with transverse SAW solely, the time for the bubble to detach laterally from the downward-facing heating surface is shortened by nearly 33%, and the removal speed of the bubble is also increased by nearly 45%. It indicates that SAW excitation can serve as an effective approach for active control and enhancement of boiling heat transfer on the downward-facing heating surface.

LESA: Longitudinal Elastic Shape Analysis of Brain Subcortical Structures

Over the past 30 years, magnetic resonance imaging has become a ubiquitous tool for accurately visualizing the change and development of the brain’s subcortical structures (e.g., hippocampus). Although subcortical structures act as information hubs of the nervous system, their quantification is still in its infancy due to many challenges in shape extraction, representation, and modeling. Here, we develop a simple and efficient framework of longitudinal elastic shape analysis (LESA) for subcortical structures. Integrating ideas from elastic shape analysis of static surfaces and statistical modeling of sparse longitudinal data, LESA provides a set of tools for systematically quantifying changes of longitudinal subcortical surface shapes from raw structure MRI data. The key novelties of LESA include: (i) it can efficiently represent complex subcortical structures using a small number of basis functions and (ii) it can accurately delineate the spatiotemporal shape changes of the human subcortical structures. We applied LESA to analyze three longitudinal neuroimaging datasets and showcase its wide applications in estimating continuous shape trajectories, building life-span growth patterns, and comparing shape differences among different groups. In particular, with the Alzheimer’s Disease Neuroimaging Initiative (ADNI) data, we found that Alzheimer’s Disease (AD) can significantly speed the shape change of the lateral ventricle and the hippocampus from 60 to 75 years olds compared with normal aging. Supplementary materials for this article are available online.

Determination of Optimum Machining Parameters for Face Milling Process of Ti6A14V Metal Matrix Composite.

This paper shows the novel approach of Taguchi-Based Grey Relational Analysis of Ti6Al4V Machining parameter. Ti6Al4V metal matrix composite has been fabricated using the powder metallurgy route. Here, all the components of TI6Al4V machining forces, including longitudinal force (Fx), radial force (Fy), tangential force (Fz), surface roughness and material removal rate (MRR) are measured during the facing operation. The effect of three process parameters, cutting speed, tool feed and cutting depth, is being studied on the matching responses. Orthogonal design of experiment (Taguchi L9) has been adopted to execute the process parameters in each level. To validate the process output parameters, the Grey Relational Analysis (GRA) optimization approach was applied. The percentage contribution of machining parameters to the parameter of response performance was interpreted through variance analysis (ANOVA). Through the GRA process, the emphasis was on the fact that for TI6Al4V metal matrix composite among all machining parameters, tool feed serves as the highest contribution to the output responses accompanied by the cutting depth with the cutting speed in addition. From optimal testing, it is found that for minimization of machining forces, maximization of MRR and minimization of Ra, the best combinations of input parameters are the 2nd stage of cutting speed (175 m/min), the 3rd stage of feed (0.25 mm/edge) as well as the 2nd stage of cutting depth (1.2 mm). It is also found that hardness of Ti6Al4V MMC is 59.4 HRA and composition of that material remain the same after milling operation.

Effect of initial solidification characteristics on longitudinal crack formation in thin slab caster

ABSTRACT Longitudinal surface crack has been one of the serious problems of thin slab casting (TSC). The present study was undertaken to comprehend the characteristics of longitudinal facial crack (LFC) and minimise the same in hot rolled low carbon steel sheets produced through thin slab casting and rolling (TSCR). Macro-structural characteristics of solidified shell has been investigated and correlated with plant observations. The centre and edges of funnel region showed maximum propensity of LFCs. TSC solidification is initiated with fine columnar dendrites which gradually coarsened towards the slab centre. This has been attributed to the characteristics of liquid steel flow instability in the upper mould region. Meniscus flow instability may lead to non-uniform heat transfer besides mould flux entrapment in the solidifying shell. Examination revealed that the mould hot faces ware covered with brass containing voids and cracks. Brass formation was found to be the most prominent around the meniscus of the wide hot face, which gradually faded out towards the mould exit. Tramp elements (zinc and lead) in liquid steel were found to be responsible for harmful brass formation during casting. The present findings were implemented in plant operation to minimise its concentration.

Analysis of longitudinal leaky surface acoustic waves on quartz thin plate bonded to similar-material substrate

The propagation and resonance properties of longitudinal leaky surface acoustic waves (LLSAWs) on bonded structures consisting of a quartz (Qz) thin plate and a Qz support substrate with different Euler angles were investigated theoretically. By using both an X-cut Qz thin plate and a Qz support substrate with optimal Euler angles, we obtained LLSAWs with a larger coupling factor, a smaller attenuation, and a lower temperature coefficient of frequency than those on a single Qz substrate. Furthermore, from the resonance properties simulated by the finite element method, the bonded structures were found to exhibit a large admittance ratio and a high quality factor, which could not be obtained when using a single Qz substrate; the bandwidth, however, was as small as 0.016%–0.086%.

A plasmonic Au-Ag janus nanoprobe for monitoring endogenous hydrogen sulfide generation in living cells

Hydrogen sulfide (H2S) is an essential intracellular gasotransmitter undertaking numerous signaling roles and physiological effects. Herein, an ingenious anisotropic gold (Au)-silver (Ag) Janus plasmonic nanoprobe was constructed based on the dark-field light scattering imaging for the detection of exogenous and endogenous H2S. In the presence of sulfide, the Ag islands as the sensing agent were susceptible to oxidation to Ag2S, which induced changes in the longitudinal localized surface plasmon resonance (LSPR) properties of Au-Ag Janus nanoparticles (JNPs), resulting in remarkable and distinctive scattering color changes as well as spectral shifts. The JNPs exhibited satisfying anti-interference capability and a good linear relationship with a low detection limit of 0.11 nM. Additionally, this distinct nanoprobe was successfully applied to monitor endogenous H2S as well as map local variations of H2S in real-time with its unique intuition and sensitivity in intracellular imaging applications. This work provided a promising application in the plasmonic detection of intracellular H2S and paved insight into the H2S-related biological process.

Structural convergence for tubulin binding of CPAP and vinca domain microtubule inhibitors

Microtubule dynamics is regulated by various cellular proteins and perturbed by small-molecule compounds. To what extent the mechanism of the former resembles that of the latter is an open question. We report here structures of tubulin bound to the PN2-3 domain of CPAP, a protein controlling the length of the centrioles. We show that an α-helix of the PN2-3 N-terminal region binds and caps the longitudinal surface of the tubulin β subunit. Moreover, a PN2-3 N-terminal stretch lies in a β-tubulin site also targeted by fungal and bacterial peptide-like inhibitors of the vinca domain, sharing a very similar binding mode with these compounds. Therefore, our results identify several characteristic features of cellular partners that bind to this site and highlight a structural convergence of CPAP with small-molecule inhibitors of microtubule assembly.

Longitudinal In Vitro Effects of Silver Diamine Fluoride on Early Enamel Caries Lesions.

This laboratory study evaluated the longitudinal surface microhardness changes in early, incipient, noncavitated, white-spot, enamel caries lesions treated with silver diamine fluoride (SDF). Five intervention groups (SDF, AgNO3, KF, 5% sodium fluoride varnish (FV), deionized water (DI)) × two-time intervals after intervention (immediate & delayed pH-cycling) resulted in 10 groups (n=18). Silver nitrate (AgNO3) and potassium fluoride (KF) groups served as controls to assist in evaluating if remineralization effects were due to the silver or fluoride component in SDF. Early, incipient, noncavitated, white-spot, enamel caries lesions were created in bovine enamel, the extent of demineralization was determined using Vickers surface microhardness (VHNlesion). Intervention treatments were applied. Half the specimens from each group underwent immediate 5-day pH-cycling, and half were stored in an incubator with artificial saliva for 2 weeks before undergoing 5-day pH-cycling. After pH-cycling, lesion hardness was evaluated using VHNpost. Specimens were then exposed to a second demineralization challenge, and lesion softening was evaluated (VHNsecdem). Hardness variables were calculated: ΔVHN = VHNpost - VHNlesion; ΔVHNsecdem = VHNsecdem - VHNpost. Data were analyzed using two-way ANOVA (α=0.05). Immediately cycled, SDF had significantly (p<0.0001) greater remineralization than DI, AgNO3, and FV. All delayed cycling groups had significantly greater remineralization than FV (p<0.0001). Significantly greater remineralization was noted in delayed AgNO3 (p≤0.0001), DI (p=0.0003), and FV (p=0.0006) compared to immediately cycled. After the second demineralization challenge, FV had significantly less surface softening than AgNO3 (p=0.0002), DI (p=0.0003), KF (p=0.0225), and SDF (p=0.0388) intervention groups. No significant difference was found between the pH-cycle timings (p=0.2710). Based the present findings, FV may be better suited than SDF to treat early, incipient, noncavitated, white-spot, enamel caries lesions.

Adaptive neuro fuzzy selection of important factors for prediction of plasmons in silver nanorods.

The major goal of this study was to find predictors of plasmon positions in silver nanorod (NR) optical absorption spectra. The goal of this study is to use an adaptive neural fuzzy inference system to identify the various input parameters for longitudinal surface plasmon resonance (LSPR) and transverse surface plasmon resonance (TSP). A seed strategy has been used for preparation of the silver NRs. During the preparation, the seed particles are synthesized in the presence of cetyltrimethylammonium bromide (CTAB). To produce the silver NRs, metal salt (AgNO3) has been added, as well as ascorbic acid (AA) and CTAB. Skillful prediction could play a pivotal role in the plasmon NR production management. The combination of CTAB and the seeds has the largest influence on the TSPR. The combination of CTAB and AA has the largest influence on the LSPR. The study considering different input parameters simultaneously, to the best of our knowledge, is the first on a small scale and should attract great general interest.

Longitudinal surface measurements of human blastocysts show that the dynamics of blastocoel expansion are associated with fertilization method and ongoing pregnancy

BackgroundDespite all research efforts during this era of novel time-lapse morphokinetic parameters, a morphological grading system is still routinely being used for embryo selection at the blastocyst stage. The blastocyst expansion grade, as evaluated during morphological assessment, is associated with clinical pregnancy. However, this assessment is performed without taking the dynamics of blastocoel expansion into account. Here, we studied the dynamics of blastocoel expansion by comparing longitudinal blastocoel surface measurements using time-lapse embryo culture. Our aim was to first assess if this is impacted by fertilization method and second, to study if an association exists between these measurement and ongoing pregnancy.MethodsThis was a retrospective cohort study including 225 couples undergoing 225 cycles of in vitro fertilization (IVF) treatment with time-lapse embryo culture. The fertilization method was either conventional IVF, intracytoplasmic sperm injection (ICSI) with ejaculated sperm or ICSI with sperm derived from testicular sperm extraction (TESE-ICSI). This resulted in 289 IVF embryos, 218 ICSI embryos and 259 TESE-ICSI embryos that reached at least the full blastocyst stage. Blastocoel surface measurements were performed on time-lapse images every hour, starting from full blastocyst formation (tB). Linear mixed model analysis was performed to study the association between blastocoel expansion, the calculated expansion rate (µm2/hour) and both fertilization method and ongoing pregnancy.ResultsThe blastocoel of both ICSI embryos and TESE-ICSI embryos was significantly smaller than the blastocoel of IVF embryos (beta -1121.6 µm2; 95% CI: -1606.1 to -637.1, beta -646.8 µm2; 95% CI: -1118.7 to 174.8, respectively). Still, the blastocoel of transferred embryos resulting in an ongoing pregnancy was significantly larger (beta 795.4 µm2; 95% CI: 15.4 to 1575.4) and expanded significantly faster (beta 100.9 µm2/hour; 95% CI: 5.7 to 196.2) than the blastocoel of transferred embryos that did not, regardless of the fertilization method.ConclusionLongitudinal blastocyst surface measurements and expansion rates are promising non-invasive quantitative markers that can aid embryo selection for transfer and cryopreservation.Trial registrationOur study is a retrospective observational study, therefore trial registration is not applicable.

Improvement of Anchorage Performance of Carbon Fiber-Reinforced Polymer Cables.

Prestressed concrete composed of steel materials is increasingly used in various social infrastructures, such as bridges (cables), nuclear containment structures, liquefied natural gas (LNG) tanks, and structural reinforcements. This study aimed to substitute the steel in bridge cables with fiber-reinforced polymers (FRPs) to prevent the damage caused by the performance degradation of corroded prestressed steel. An optimized single-anchorage system was derived by applying multiple variables, such as the surface treatment, number of insert layers, and sleeve processing companies, to improve the maximum load and bonding with the anchorage system sleeve using the carbon FRP (CFRP) cable. The B-L-4 specimen (sleeve specifications of company B, longitudinal surface treatment, and four insert layers) was determined to be the optimized single-anchorage system. When the tensile test was conducted after applying the optimized single-anchorage system to the three- and seven-multi-anchorage systems, the tensile performances of B-L-4 were 100 and 95% of the one-multi-anchorage system, respectively. Considering that the problems associated with the construction of three- and seven-multi-anchorage systems have been addressed, these systems can be applied to actual bridges in the future, and can significantly benefit their maintenance.

Nonlinear characterization of stress wave factor for plastic damage of A7N01P-T4 aluminum alloys

This paper studies the relationship between plastic damage and the ultrasonic nonlinear coefficient by changing the interior plastic strain of A7N01P-T4 aluminum alloys. An effective evaluation of the plastic damage of tensile test specimens was made by comparing with two different nonlinear ultrasonic detection methods, namely, nonlinear longitudinal wave method and surface wave method. The nonlinear coefficient of the stress wave factor was introduced to characterize the plastic damage for metallic materials. The results showed that with the increasing plastic damage degree, the nonlinear coefficient increased slowly at the early stage of yield hardening (3%) and then increased rapidly at the middle stage (3–5%). It is concluded that the nonlinear longitudinal wave is more suitable for point measurement and its sensitivity is lower than that of the longitudinal wave.

Multicolorimetric and fluorometric dual-modal immunosensor for histamine via enzyme-enabled metallization of gold nanorods and inner filter effect of carbon dots

Histamine (HA) is one of the key causative agents associated with allergies and food poisoning. The accurate and convenient detection of HA is highly required to avert HA toxicity and ensure food safety. Herein, a multicolorimetric and fluorometric dual-readout immunosensor for HA detection was developed based on an alkaline phosphatase (ALP) enabled multicolor change reaction and fluorescence quenching of carbon dots (CDs) resulting from the metallization of gold nanorods (Au NRs). In this immunosensor, ALP is employed as labeling enzyme which can efficiently catalyze the hydrolysis of ascorbic acid 2-phosphate into ascorbic acid (AA). Then, the resultant AA can reduce Ag+ into silver monomer, and a silver shell is deposited on the surface of Au NRs to form Au/Ag core-shell nanorods (Au NRs@Ag). This leads to the blue-shift of the longitudinal local surface plasmon resonance peak of Au NRs and a vivid multicolor variation. Meanwhile, the fluorescence of CDs can be gradually quenched via inner-filter effect by the resultant Au NRs@Ag. Multicolorimetric assay allows a semiquantitative detection with a visible detection limit of 0.25 mg/L, and fluorometric assay provides a sensitive and accurate quantitative detection with a detection limit of 0.08 mg/L. The immunosensor not only fulfills the reliable and accurate detection requirements but also fits different testing needs for both laboratory and on-site detection.

Theoretical simulation of nonlinear regulation of wall thickness dependent longitudinal surface plasmon in pentagonal gold nanotubes

In this paper, the longitudinal plasmon mode optical properties and localized electric field distribution of a single pentagonal gold nanotube are investigated for the first time by the discrete dipole approximation. It is found that pentagonal gold nanotube has stronger electric field distribution compared with circular gold nanotubes when the incident wavelength is located at the plasmon resonance peak. Additionally, we observed that the longitudinal plasmon resonance peak can blue shift nonlinearly with increasing wall thickness, but red shifts linearly with the increase of the length of the pentagonal gold nanotube. The localized electric field analysis reveals that the longitudinal plasmon peak of the pentagonal gold nanotube originates from the dipole resonance mode. The local electric field intensity is controlled by the wall thickness and length. Notably, the effect of wall thickness on the longitudinal plasmon resonance and electric field enhancement can be attributed to the change of the plasmon coupling position and intensity. This work has enriched the theoretical research of pentagonal gold nanotubes and provided ideas for the preparation of high sensitivity nanoprobes biosensors.

Controlling the Optical Properties of Gold Nanorods in One-Pot Syntheses.

We present the characterization of the CTAB-oleate controlled synthesis of gold nanorods (AuNRs). Concentrations of key compounds in the synthetic system were varied in the presence of oleate, including HCl, borohydride, silver nitrate, and ascorbic acid. The longitudinal surface plasmon resonance peak was sensitive to changes in all concentrations. Reducing the concentration of Ag ions below 66 μM led to slower reaction kinetics and incomplete Au reduction. Variation of the ascorbic acid concentration revealed that oleate is responsible for around 44% of reduction of Au3+ to Au+ before nucleation in these experiments. Increasing the oleate concentration significantly slows the growth kinetics and leads to much longer synthesis times of above 12 h for reaction completion. These observations will enable the design of better methods of synthesizing of AuNRs using binary surfactants.

In Situ Partial Sulfidation for Preparing Cu/Cu2−xS Core/Shell Nanorods with Enhanced Photocatalytic Degradation

Herein, we report an approach to prepare Cu/Cu2−xS core/shell nanorods by in situ sulfidation of copper nanorods. Firstly, copper nanorods with tunable longitudinal surface plasmon resonances were synthesized by a seed-mediated method using Au nanoparticles as seeds. A convenient in situ sulfidation method was then applied to convert the outermost layer of Cu nanorods into Cu2−xS, to increase their stability and surface activity in photocatalytic applications. The thickness of Cu2−xS layer can be adjusted by controlling the amount of S source. The Cu/Cu2−xS core/shell nanorods exhibits two characteristic surface plasmon resonances located in visible and near-infrared regions, respectively. The photocatalytic performances of Cu nanorods and their derivatives were evaluated by measuring the degradation rate of methyl orange dyes. Compared with Cu nanorods, the Cu/Cu2−xS core/shell nanorods demonstrate more than a 13.6-fold enhancement in the degradation rate at 40 min. This work suggests a new direction for constructing derivative nanostructures of copper nanorods and exploring their applications.

Searching for high similarity of longitudinal local surface plasmon resonance in gold and silver nanobipyramids

Metal nanobipyramids is a new type of nanoparticle, that has been widely studied due to their remarkable LSPR properties. In this paper, gold and silver nanobipyramids were simulated by the finite difference time domain (FDTD) method. The results show that the longitudinal optical properties and electric field enhancement of gold and silver nanobipyramids are almost the same under a specific aspect ratio. The above results are verified by the core-shell structure. The research results of the two extreme states of absolute sharpness and non-sharpness of nanobipyramids show that the gold and silver nanobipyramids with different sharpness can achieve high similarity of longitudinal local surface plasmon resonance by changing their aspect ratio. The possible reasons for the high similarity of the electric field enhancement effect and extinction phenomenon of gold and silver nanobipyramids under a specific aspect ratio are analyzed by the plasmon resonance mechanism and Gans theory. These results have a great reference significance for the study of gold and silver nanoparticles, including their related properties and applications.

Highly sensitive visual colorimetric sensor for trichlorfon detection based on the inhibition of metallization of gold nanorods

In this study, a highly sensitive visual colorimetric sensor was designed for the detection of trichlorfon based on inhibiting ascorbate oxidase (AAO)-induced metallization of gold nanorods (Au NRs). Ascorbic acid (AA) can reduce silver ion (Ag+) to metal silver (Ag) that will be deposited on the surface of Au NRs, which results in the blue shift of longitudinal localized surface plasmon resonance (LSPR) peak of Au NRs, accompanying by perceptible color changes from red to cyan to red to yellow. In the presence of trichlorfon, the activity of AAO will be inhibited, resulting in less AA is hydrolyzed to dehydroascorbic acid (DHA), and therefore more Ag+ is reduced to Ag by AA. Under the optimized conditions, detection of trichlorfon has a wide linear range of 27.8–11111.1 μg/L with a limit of detection as low as 132.6 ng/L. Moreover, the sensor has a good sample spiked recovery (84.7–96.8%) for the determination of trichlorfon in lake water samples. The proposed method can achieve rapid analysis (about 10 min) of trichlorfon with simple operation when there are no other types of organophosphorus pesticides in the real samples.

Mechanisms of Friction Reduction in Longitudinal Ultrasonic Surface Haptic Devices With Non-Collinear Vibrations and Finger Displacement.

Friction reduction using ultrasonic longitudinal surface vibration can modify the user perception of the touched surface and induce the perception of textured materials. In the current paper, the mechanisms of friction reduction using longitudinal vibration are analyzed at different finger exploration velocities and directions over a plate. The development of a non-Coulombic adhesion theory based on experimental results is evaluated as a possible explanation for friction reduction with vibrations that are non-collinear with the finger displacement. Comparison with experimental data shows that the model adequately describes the reduction in friction, although it is less accurate for low finger velocities and depends on motion direction.

Automated detection of laser track contours for analysis of laser polishing process stability

Laser polishing (LP) is an advanced finishing technology used to improve surface quality through laser remelting of the surface topography. A thorough understanding of the surface topography formation during laser remelting is critically required to monitor, optimize, and control the LP process. For this purpose, a method for automated detection of laser-material interaction contour along a laser track was developed and was used to estimate the stable and unstable conditions of the LP process. Process instabilities can yield to significant variations of the longitudinal surface profiles and the remelted track width along the laser path. The proposed method relies on a first derivative-based determination of the two spatial contour boundaries that delimit the width of the remelted laser track. The developed technique was tested and applied to two experimentally obtained laser tracks under non-stable and stable LP process conditions. This study demonstrates the efficient applicability of the automated contour detection in advanced analysis, monitoring, optimization, and control of the LP process stability.