Stripe Surface Research Articles

Drainage during Condensation on Microgrooved Biphilic Surfaces.

In this work, we investigate and compare the condensation behavior of hydrophilic, hydrophobic, and biphilic microgrooved silicon samples etched by reactive ion etching. The microgrooves were 25 mm long and 17-19 μm deep with different topologies depending on the etching process. Anisotropically etched samples had 30 μm wide rectangular microgrooves and silicon ridges between them. They were either left hydrophilic or covered with a hydrophobic fluorocarbon or photoresist layer. Anisotropically etched samples consisted of 48 μm wide semicircular shaped microgrooves, 12 μm wide silicon ridges between them, and a 30 μm wide photoresist stripe centered on the ridges. The lateral dimensions were chosen to be much smaller than the capillary length of water to support drainage of droplets by coalescence rather than droplet sliding. Furthermore, to achieve a low thermal resistance of the periodic surface structure consisting of water-filled grooves and silicon ridges, the trench depth was also kept small. The dripped-off total amount of condensate (AoC) was measured for each sample for 12 h under the same boundary conditions (chamber temperature 30 °C, cooling temperature 6 °C, and relative humidity 60%). The maximum increase in AoC of 15.9% (9.6%) against the hydrophilic (hydrophobic) reference sample was obtained for the biphilic samples. In order to elucidate their unique condensation behavior, in situ optical imaging was performed at normal incidence. It shows that the drainage of droplets from the stripe's surface into the microgrooves as well as occasional droplet sliding events are the dominant processes to clear the surface. To rationalize this behavior, the Hough Circle Transform algorithm was implemented for image processing to receive additional information about the transient droplet size and number distribution. Postprocessing of these data allows calculation of the transient water load on the stripe's surface, which shows an oscillatory behavior not previously reported in the literature.

Visible light-induced crosslinking enables highly permeable and chlorine-resistant polyamide membranes for water purification

Nanofiltration (NF) based purification technology plays a growing role in water softening, wastewater reuse, and drinking water production, whose core component is the thin-film composite (TFC) polyamide (PA) surface separating layer with high water permeation and significant antifouling and chemical resistance. Strengthening water transport with simultaneously improving chemical tolerance and fouling resistance accords with the demands for sustainable water treatment. In this work, a photo-assisted crosslinked NF membrane with a regulated interlaced stripe surface morphology was fabricated through grafting 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) into the PA network during visible light irradiation. Surface structures and chemical features were characterized, and the NF performance, antifouling and chlorine resistance were systematically evaluated. The optimal membrane with AMPS molecules carrying sulfonyl groups crosslinked in the PA network was rendered electronegative charge, uniformly narrowed pore size, improved hydrophilicity, and higher crosslinking degree. The water permeation was augmented to 30.5 L m−2 h−1·bar−1 for the optimal membrane, four times more advanced than the pristine membrane with a water permeability of 5.9 L m−2 h−1·bar−1, and the divalent salt retention was improved to 99.7%. In addition, the optimal membrane also exhibited outstanding chlorine tolerance, fouling removal, and antifouling capacity. The flux recovery ratio (FRR) of the best membrane outperformed that of the pristine membrane and the flux declined more slowly in the whole fouling cycle testing. This work provides a novel avenue for fabricating high-efficiency TFC membranes with great water permeation and fouling resistance.

Preparation of 3D Printed Polylactic Acid/Bacterial Cellulose Composite Scaffold for Tissue Engineering Applications.

Bacterial cellulose (BC) has become a universal biomaterial owing to its intrinsic properties. BC fibers are composed of microfibers with a diameter of 3-4 nm into fiber bundles with a thickness of 40-60 nm, and interweave with each other to form a well-developed ultra-fine network structure. Polylactic acid (PLA) has good mechanical properties and excellent biocompatibility and biodegradability. Therefore, PLA has been widely applied in tissue engineering. Addressed herein is a novel type of PLA/BC (PLA/BC) composite scaffold prepared by 3D printing (3D), 3D modeling of the required porous membrane material support established in the computer, and decomposition of the model into 5 layer 20 μM sheets. The range of PLA loadings assessed in this work was 1.0 wt.%, 1.5 wt.%, and 2.0 wt.%, and its physicochemical properties and biological properties were characterized and evaluated. Tensile strength of PLA/BC composite scaffolds increased to 66.49 MPa compared to that of a pure BC film (25.61 MPa). Hydrophilicity was tunable with the amount of added PLA. In this paper, the effects of 3D round hole and stripe surface topology on cell growth behavior were characterized. Schwann cells (SCs) adhered to the surface of the 3D composite membrane successfully, and their proliferation rate on the surface of the regular circular pore and stripe structure was better than that of the smooth surface. Erythrocyte fixation and platelet adhesion experiments showed that the 3D composite scaffold had excellent blood compatibility. Further degradation studies showed that loose structures appeared after 1 week, and structural defects began after 3 weeks. The in vitro degradation results showed that the degradation rate of the BC membrane in simulated body fluid after 6 weeks was 14.38%, while the degradation rate of the PLA/BC composite scaffold was 18.75%.

Recognition of adsorption phase transition of polymer on surface by neural network

Traditional Monte Carlo simulation requires a large number of samples to be employed for calculating various physical parameters, which needs much time and computer resources due to inefficient statistical cases rather than mining data features for each example. Here, we introduce a technique for digging information characteristics to study the phase transition of polymer generated by Monte Carlo method. Convolutional neural network (CNN) and fully connected neural network (FCN) are performed to study the critical adsorption phase transition of polymer adsorbed on the homogeneous cover and stripe surface. The data set (conformations of the polymer) is generated by the Monte Carlo method, the annealing algorithm (including 48 temperatures ranging from <i>T</i> = 8.0 to <i>T</i> = 0.05) and the Metropolis sampling method, which is marked by the state labeling method and the temperature labeling method and used for training and testing of the CNN and the FCN. The CNN and the FCN network can not only recognize the desorption state and adsorption state of the polymer on the homogeneous surface (the critical phase transition temperature <i>T</i><sub>C</sub> = 1.5, which is close to the critical phase transition temperature <i>T</i><sub>C</sub> = 1.625 of the infinite chain length of polymer adsorbed on the homogeneous surface regardless of the size effect), but also recognize the desorption state, the single-stripe adsorption state and the multi-stripe adsorption state of polymer on the stripe surface(the critical phase transition temperature <i>T</i><sub>1</sub> = 0.55 and <i>T</i><sub>2</sub> = 1.1, which are consistent respectively with <i>T</i><sub>1</sub> = 0.58 and <i>T</i><sub>2</sub> = 1.05 of polymer adsorbed on the stripe-patterned surface derived from existing research results). We obtain almost the same critical adsorption temperature by two different labeling methods. Through the study of the relationship between the size of the training set and the recognition rate of the neural network, it is found that the deep neural network can well recognize the conformational state of polymer on homogeneous surface and stripe surface of a small set of training samples (when the number of samples at each temperature is greater than 24, the recognition rate of the polymer is larger than 95.5%). Therefore, the deep neural network provides a new calculation method for polymer simulation research with the Monte Carlo method.

Phosphor-free white emission from InGaN quantum wells grown on in situ formed submicron-scale multifaceted GaN stripes

We demonstrate in situ self-organization of multifaceted GaN stripes on m-sapphire substrates. The GaN stripes aligned along <1¯1¯23> with submicron-scale {112¯2}, {101¯1}, {202¯1}, {112¯4}, and {0001} facets are identified and employed as growth templates of InGaN quantum wells (QWs). Under identical growth conditions the emission spectrum of the InGaN QWs is determined by the GaN stripe shaping and atomic structures of the stripe surface. For instance, the growth rate (thickness) of the InGaN QWs is proportional to the layer spacing and dangling bond density of specific growth face and plays a key role in emission wavelength. Accordingly, using the stripe templates the InGaN QWs on different stripe facets have different emission wavelengths. Broad photoluminescence peak covering ultraviolet, blue, green, yellow, amber, and red emissions is observed for the InGaN QWs grown on various sidewall facets of the stripe templates. The chromaticity diagram indicates a cool-daylight white emission with a correlated color temperature of 5997 K.

Long-Range Surface Plasmon-Polariton Waveguide Biosensors for Disease Detection

We review recent progress on the application of long-range surface plasmon-polariton waveguide biosensors for disease detection. The biosensors are constructed from metal stripe waveguides cladded in Cytop with etched microfluidic channels to expose the stripe surface to the sensing fluid. The waveguides support long-range surface plasmons in integrated optics geometries when excited in an end-fire manner. Application of straight waveguide biosensors to the detection of leukemia, dengue infection, and urinary tract infection in complex fluids such as blood serum, blood plasma, and urine is reviewed.

Stripe Surface Defect Image Recognition by Supervised Tree ISOMAP and Incremental GRNN

The new isometric mapping dimensionality reduction algorithm with Incremental Generalized Regression Network has been primarily recognized for stripe surface defects images with the typical characteristics of complex texture, non-uniform image size, asymmetrical number of sample classes, variation illumination environment. This method is suitable to resolve the problem of “short circuit”, stored internal structure in lower dimension space. In addition, the algorithm parameters influence on the stripe surface defect images is greatly reduced. The finally experiment results show that it is effective and efficient for stripe surface defects with the highest recognition rate of stripe surface defect can reach to 97%, and the highest recognition rate of complex stripe surface defect can reach to 74%

Hydrostatic strain enhancement in laterally confined SiGe nanostripes

Strain engineering in SiGe nanostructures is fundamental for the design of optoelectronic devices at the nanoscale. Here we explore a new strategy, where SiGe structures are laterally confined by the Si substrate, to obtain high tensile strain yet avoid the use of external stressors, thus improving the scalability. Spectromicroscopy techniques, finite element method simulations, and ab initio calculations are used to investigate the strain state of laterally confined Ge-rich SiGe nanostripes. Strain information is obtained by tip-enhanced Raman spectroscopy with an unprecedented lateral resolution of \ensuremath{\sim}30 nm. The nanostripes exhibit a large tensile hydrostatic strain component, which is maximal at the center of the top free surface and becomes very small at the edges. The maximum lattice deformation is larger than the typical values of thermally relaxed Ge/Si(001) layers. This strain enhancement originates from a frustrated relaxation in the out-of-plane direction, resulting from the combination of the lateral confinement induced by the substrate side walls and the plastic relaxation of the misfit strain in the (001) plane at the SiGe/Si interface. The effect of this tensile lattice deformation at the stripe surface is probed by work function mapping, which is performed with a spatial resolution better than 100 nm using x-ray photoelectron emission microscopy. The nanostripes exhibit a positive work function shift with respect to a bulk SiGe alloy, quantitatively confirmed by electronic structure calculations of tensile-strained configurations. The present results have a potential impact on the design of optoelectronic devices at a nanometer-length scale.

Clinical failure analysis of contemporary ceramic-on-ceramic total hip replacements

The present study investigates the performance of ceramic-on-ceramic total hip replacements by combining a retrieval analysis with a survivorship analysis to elucidate mechanisms that led to clinical failure. Semiquantitative surface damage assessment, contact profilometry, contour measurements, and scanning electron microscopy were performed to characterize the types and quantify the extent of surface damage on the retrieved ceramic components. The implantation period was positively correlated with both damage scores of the femoral heads (R = 0.573, p < 0.001) and the acetabular cups (R = 0.592, p < 0.001). Increased maximal out-of-roundness values of the femoral heads correlated with both increased metal transfer damage score (R = 0.384, p = 0.023) and increased stripe damage score (R = 0.729, p ≤ 0.001) of the acetabular liners. The damage rate (damage score/year) for both the retrieved heads and acetabular liners was at least 2.2-fold greater at inclination angles of >45° than the damage rate at inclination angles of ≤45°. For the retrieved femoral heads only, the linear wear rate of 25.5 ± 21.3 µm/year at inclination angles of >45° was 6-fold greater than the linear wear rate of 4.2 ± 2.3 µm/year at inclination angles of ≤45°. Metal transfer on the ceramic bearing surface could possibly contribute to fluid-film starvation and, in combination with an increased inclination angle, may facilitate an adhesive wear mechanism associated with stripe surface damage. At our institution, the clinical survivorship of ceramic-on-ceramic total hip replacements was 98.9% (a total of 9 out of 815 patients were revised within 10 years after total hip arthroplasty) with revision as the end point, suggesting their safe use in younger patients.

Detection of common defects on oranges using hyperspectral reflectance imaging

To detect various common defects on oranges, a hyperspectral imaging system has been built for acquiring reflectance images from orange samples in the spectral region between 400 and 1000 nm. Oranges with insect damage, wind scarring, thrips scarring, scale infestation, canker spot, copper burn, phytotoxicity, heterochromatic stripe, and normal surface were studied. Hyperspectral images of samples were evaluated using principal component analysis (PCA) with the goal of selecting several wavelengths that could potentially be used in an in-line multispectral imaging system. The third principal component images using six wavelengths (630, 691, 769, 786, 810 and 875 nm) in the visible spectral (VIS) and near-infrared (NIR) regions, or the second principal component images using two wavelengths (691 and 769 nm) in VIS region gave better identification results under investigation. However, the stem-ends were easily confused with defective areas. In order to solve this problem, representative regions of interest (ROIs) reflectance spectra of samples with different types of skin conditions were visually analyzed. The researches revealed that a two-band ratio (R875/R691) image could be used to differentiate stem-ends from defects effectively. Finally, the detection algorithm of defects was developed based on PCA and band ratio coupled with a simple thresholding method. For the investigated independent test samples, accuracies of 91.5% and 93.7% with no false positives were achieved for both sets of selected wavelengths using proposed method, respectively. The disadvantage of this algorithm is that it could not discriminate between different types of defects.

Repeatability of Mobile Retroreflectometer Unit for Measurement of Pavement Markings

The mobile retroreflectometer unit (MRU) has been recognized by highway agencies as an appealing alternative to handheld retroreflectometers because of its improved safety and efficiency. Over the past 4 years, the Florida Department of Transportation has been researching the use of the MRU for evaluating pavement markings continuously and reliably at traffic speeds. Because the stripe surface is nonuniform and the measurement process relies on the operator-driven instrument device, there is some uncertainty in evaluating pavement markings with the MRU. As part of the broader effort for MRU implementation, this research assesses MRU precision in repeatability for pavement marking retroreflectivity. Six designated sections of roadway were selected at random for testing on various pavement surfaces and pavement stripes (paint and thermoplastic). Retroreflectivity data were collected only on the white edge lines of the test sites. The survey limits were selected so that the effect of nonretroreflective-related variables, such as breaks in the pavement markings, inclines, declines, and curves in the roadway, could be minimized. The data were analyzed to determine the pavement marking characteristics at each test location for retroreflectivity at 80 km/h (50 mph) using the reduced 30-m geometry standard. Results indicated that the retroreflectance values from two properly conducted tests using the same MRU on the same pavement marking should not differ by more than 20.1 mcd/m2/lux or 6.7% at a 95% confidence level for retroreflectivity values ranging between 200 and 450 mcd/m2/lux. This paper presents a description of the testing program, the data collection effort, and the subsequent analyses and findings.

Growth of sexithiophene crystals on Cu(1 1 0) and Cu(1 1 0)-(2×1)O stripe phase—The influence of surface corrugation

Sexithiophene (6T) films have been grown by molecular beam deposition on two different substrates: a clean Cu(1 1 0) single crystal surface and a 1:1 Cu(1 1 0)/Cu(1 1 0)-(2×1)O stripe surface. Both substrates serve as atomically ordered two-fold symmetric templates, which induce epitaxial growth of the 6T crystallites due to surface corrugations. On both surfaces, 6T crystallizes in its low-temperature phase with (0 1 0) being the main crystallographic orientation of the 6T crystals relative to the substrate surface. Two different epitaxial growth behaviors are observed: while on the oxygen-passivated surface the long molecular axes of the 6T molecules are aligned exactly along the oxygen rows, small tilt angles relative to the densely packed copper rows are found on the clean copper surface. Classical misfit calculations seem to be insufficient to describe the observed epitaxial crystallization of sexithiophene. On the striped surface clean copper- and oxygen-passivated copper regions are offered on the same surface. The dominant crystalline fraction grows in an orientation also found on the fully reconstructed Cu(1 1 0)-(2×1)O surface where it grows exclusively in this orientation. A model that explains these experimental findings is discussed and it turns out that the sticking anisotropy is the dominating effect.

Nanostructuring Process in Femtosecond Laser Ablation of Patterned Thin Film Surfaces

To study the physical mechanism of femtosecond (fs) laser induced nanostructuring on solid surfaces, we observed the initial stage of morphological change on diamond-like carbon and titanium nitride films in fs laser ablation at low fluence. Using the thin film targets patterned with submicrometer-size stripes, we have found that the nanostructure starts to be formed on the stripe along the direction perpendicular to the laser polarization. The experimental results have shown that nanoscale ablation for the nanostructuring is preferentially initiated with the enhancement of localized electric field on the stripe surface with high curvature.

Nanoscale ablation on patterned diamondlike carbon film with femtosecond laser pulses

The authors have studied the origin of nanostructure formation on diamondlike carbon film in femtosecond laser ablation at low fluence. Using the thin film target patterned with submicrometer-size stripes, they have observed that the nanostructure starts to be formed on the crest of stripes along the direction perpendicular to the laser polarization. The experimental results have shown that nanoscale ablation for the nanostructuring would preferentially be initiated by the enhancement of localized electric field on the stripe surface with high curvature.

INFLUENCE OF LOCAL SHAPE WAVE ON RIBBING OF COLD-ROLLED COIL

Against the ribbing problem that it is easy to produce additional shape wave and degraded product on the surface of stripe after the uncoil on the process of curl, and on the base of quantities of the field experiment and the research of theory, a set of judgment standard about the theory of big and small local shape wave is put forward combining with the relevant characteristics of small local shape wave and big local shape wave. At the same time, the problems that include the origin of axial force caused by big local shape wave on the process of ribbing, the calculation of critical bucking stress and axial force in the zone of ribbing are analysed systemic. After that, against the two different conditions of small local shape wave and big local shape wave, the two corresponding mathematic models about the calculation of ribbing value are set up. After the ribbing value in the different conditions are simulated quantitatively and compared with field data, the statistic indicate that the deviation value of model data with field data is within ten percents and the maximal deviation value in one time is within fifteen percents, which reach relatively high accuracy and meet the requiremet for prediction accuracy of ribbing value on the project. It also bring forward the convincing theoretical basis for the ribbing cure of the factory and creates vast economic returns.

Surface Structures in Thin Polymer Layers Caused by Coupling of Diffusion‐Controlled Marangoni Instability and Local Horizontal Temperature Gradient

AbstractSummary: Surface tension‐driven Marangoni convection causes the formation of regular surface structures in drying polymer layers. The shape of the surface structures formed during solvent evaporation depends on layer and interfacial dynamic parameters as well as external factors. The influence of a horizontal radial temperature gradient produced by a point heat source below the polymer layer on the diffusion‐controlled Marangoni instability has been studied. In the region of the lateral temperature gradient, radial surface flow coupled with the interfacial instability leads to stripe, ladder, chevron and/or labyrinthine surface structures.Stepped ladder structures in a poly(vinyl butyral) layer produced by interfacial instability and heating with an ultrasonic sonotrode below the layer substrate.magnified imageStepped ladder structures in a poly(vinyl butyral) layer produced by interfacial instability and heating with an ultrasonic sonotrode below the layer substrate.

Near-field observation of surface plasmon polariton propagation on thin metal stripes

We use a photon scanning tunneling microscope to probe the field of surface plasmon polariton modes excited on finite-width thin metal films (metal stripes). We first investigate the coupling between surface plasmons launched by a focused beam on a homogeneous thin film and the modes sustained by metal stripes of different widths. We show that, if the width of the metal stripe is about a few micrometers, a strong coupling with the stripe modes can be achieved at visible frequencies. A sharp transverse confinement of the field associated with the surface plasmon modes propagating on the metal stripe is unambiguously observed on the constant height photon scanning tunneling microscope images. The back-reflection of these modes at the end of the stripe leads to a surface-wave interference pattern from which the wavelength of the stripe surface plasmon modes is directly measured. We finally demonstrate that metal stripes could be used for optical addressing purposes at the micrometer scale since a stripe with a triangularly shaped termination performs the focusing of the stripe surface plasmon field.

Stress-Driven Formation of Self-Assembled InGaAs Islands on Sub-Micron Metal-Patterned Substrate

ABSTRACTA stress-driven formation of self-assembled InGaAs islands has been studied by the growth on GaAs (100) substrates with sub-micron platinum stripe pattern. Islands or quantum dots preferentially nucleate at the boundary of metal patterns. In addition, a quantum dot-free region near the boundary of the metal pattern is found. Those results are attributed to the stress between metal stripe and GaAs surface, which produces a laterally stressed region around the metal stripe. Adatoms on this region preferentially migrate toward the edge of metal stripes with maximum stress. This result may show a possible way for the interconnection between randomly distributed self-assembled quantum dots and metal stripes.

Variational and finite element analyses of nonlinear strip optical waveguides

Abstract A new, iterative finite element scheme for solving nonlinear wave guiding problems is proposed. Unlike previous numerical methods, this approach gives both the stable and unstable stationary solutions of a nonlinear strip waveguide. We use a double gaussian trial function to solve the same problem by variational principles. This approximation gives very good results and provides a simple model to characterize nonlinear stationary waves. The influence of waveguide parameter on nonlinear behaviour is discussed. We also apply both the variational and finite methods to analyze the stripe surface waves at a linear-nonlinear interface.

Ultrastructure of feeding in the karyorelictean ciliate Tracheloraphis examined by scanning electron microscopy

The karyorelictean ciliate Tracheloraphis is considered to be among the most primitive of the extant ciliates based on both nuclear and somatic characters. These organisms lack the elaborate oral ciliation present in most ciliates. Their mode of ingestion is a type of phagocytosis through a non-ciliated region, the glabrous stripe, which runs the length of the cell. This type of ingestion is reminiscent of feeding in amoebae and some flagellate groups. It is possible that ciliate oral structures evolved within the karyorelictean ciliates from an ancestor resembling Tracheloraphis. We studied the ingestion process in a Tracheloraphis species from the Chesapeake Bay using scanning electron microscopy. The results indicate that the anterior terminus of the organism is not involved in the actual ingestion process, only the glabrous stripe. There is some interaction between the food particle and the surface of the stripe, possibly mediated by a substance secreted by the underlying extrusomes. The somatic cilia do not appear to be involved. The stripe invaginates at the ingestion site engulfing the particle. The cell becomes greatly distended at this site, but neither the anterior nor posterior terminus is affected.