Concave Hemisphere Research Articles

Ultraflexible and Ultrasensitive Near‐Infrared Organic Phototransistors for Hemispherical Biomimetic Eyes

AbstractThe diverse biological eyes vision systems found in nature can provide attractive design inspiration for near‐infrared (NIR) imaging devices. Outstanding features of the retina are its concave hemisphere geometry and high‐sensitivity image acquisition, which simplify the optical complexity of the eye and improve the imaging quality of visual perception. However, developing high‐performance NIR biomimetic imaging systems with these characteristics is extremely challenging due to the limitations of their hemisphere‐like structures, constituent materials, and conventional imaging modules. Here, a hemispherical biomimetic eyes imaging system based on ultraflexible all‐polymer heterojunction NIR phototransistors is presented. The device features a self‐supporting ultrathin (≈659 nm) NIR imaging structure that can maintain stable photoelectric performance while adhering to the human body or arbitrary‐shaped objects and have extraordinary photosensitivity (≈106) under dim light conditions (0.038 mW cm−2, 808 nm). Based on the versatile NIR device array, hemispherical ultrasensitive NIR biomimetic eyes are successfully achieved and higher‐resolution imaging is realized. Results demonstrated in this work provide a new strategy for constructing ultraflexible and ultrasensitive NIR photodetectors, showing remarkable application potential in next‐generation visual prosthetics and intelligent bioimaging systems.

Results of seeder pneumatic system distributor and aero-product stream flow in the pipeline numerical studies

Seed drills with a seed metering device and a pneumatic system of flow stream and distribution of grain seeds to the coulters of the seeder with pneumatic sowing have become widespread in the sphere of agriculture. The aim of this study was to establish the functional dependence of the aero-product stream flow nature in the pipeline and in the grain seeder distributor. The research method involved numerical studies of the developed 3D model of the seeder pneumatic system. The influence of the geometric features of the internal cavity of the distributor top of the seeder pneumatic system, the flow rate in the pipeline in the range from 15 to 25 m/s, the concentration of seeds in the flow stream from 0.52 to 1.57 kg/kg air were taken into account. The values of static, dynamic and total pressure, pressure losses by sections, rates of flow streams in the areas, areas of intense mechanical impact (surface wear) were studied. The regression equations of these indicators have been obtained the factors studied being taken into consideration. The greatest pressure losses have been observed in the distributortops with a cap having the shape of a concave hemisphere. The flat surface of the cap makes it possible to achieve intermediate pressure losses in the distributor top. The smallest pressure loss is observed in the distributor top with a convex cone-shaped cap.

The relationship between mouse lung adenocarcinoma at different stages and the expression level of exosomes in serum.

Objective: The purpose of this study is to investigate the relationship between N-methylN'-nitro-N-nitrosoguanidine (MNNG)-induced lung adenocarcinoma mouse of different stages and the level of exosomes in serum. Methods: Fifty KM mice (4 weeks old, weighing 18-22 g, female) were selected for experiment. MNNG was applied to induce lung adenocarcinoma in mice for model establishment. HE staining method was used to observe pathological changes of lung tissues. Exosomes in serum were extracted, and observed under a Transmission Electron Microscopy (TEM). Western blot was employed to examine the protein levels of exosome markers TSG101 and CD63. Results: HE staining results suggested MNNG-induced lung adenocarcinoma model mice were successfully constructed. The morphology of exosomes in serum of mouse model was observed under an Electron Microscopy, showing clear membrane structures presenting as saucer or concave hemisphere. In addition, the protein level of exosome marker CD63 in advanced mouse model was significantly up-regulated relative to that in the control group. Meanwhile, the expression of exosome marker protein TSG101 was found to be markedly increased in mouse models by comparison with that in control cases. Conclusion: In lung adenocarcinoma model mice, the occurrence and development of lung adenocarcinoma are greatly correlated with the expression level of exosomes in serum, which provides theoretical basis for the diagnosis of pathological staging of lung adenocarcinoma by exosomes.

Flow and heat transfer investigation of a circular jet issuing on different types of surfaces

In the present study, flow and heat transfer characteristics of an impinging jet issuing from a circular cross-sectional pipe on a rectangular plate, convex and concave hemispheres were investigated numerically for various Reynolds numbers and jet-to-plate distances. Steady and three-dimensional Reynolds-Averaged Navier-Stokes equations were solved iteratively utilizing finite volume method. Turbulence model assessment study reveals that the transitional Shear Stress Transport k-ω turbulence model can be used for such a problem. Regardless of the geometry of the impinging surfaces, two different flow regions were detected around y/D = 3. The first region starts from the stagnation point (y/D = 0) to the edge of the rectangular plate and hemispheres (y/D = 3). In this region, the maximum heat transfer is obtained for the jet impinging on the rectangular plate. However, in the second region that covers the wall jet zone the impinging jet on the convex hemisphere provides the maximum while the concave causes the minimum heat transfer. The most efficient jet-to-plate distance is found as H/D = 2 in the first region while heat transfer does not change with distance in the wall jet zone. It was shown that Nusselt number increases with Reynolds number when the jet impinges on the concave and convex hemispheres as observed for the impinging jet on a flat plate.

Optimization of compound die piercing punches and double cutting process parameters using finite element analysis

This article investigates different types of compound die piercing punches and double cutting operation parameters in terms of optimization using finite element technique, Taguchi method, regression analysis, and analysis of variance. The article overcomes the current knowledge gap in studying various cutting edges of piercing punches such as flat, chamfered, flat edge with concave hemisphere, and convex shaped when using the compound dies in stamping operations. The analysis of the compound die is carried out using ANSYS software. The main focus is to determine the contribution of key parameters for obtaining optimum cutting tool design. The best piercing punch is selected based on minimum burr height of the product. The values of cutting process parameters and burr heights have been analyzed using Minitab software. The results obtained indicate that the burr heights of the final product are at a minimum when the sheet metals are thicker and larger when the sheets are thinner. The chamfered and convex punches provided minimum burr heights which are as low as 0.034 mm for a typical sheet metal. This study provides a better outcome compared to the available experimental data in the literature. The investigation also designed efficient compound dies resulting in improved product quality.

Dual surface modification of PDMS-based silicone implants to suppress capsular contracture

In this study, we report a new physicochemical surface on poly(dimethylsiloxane) (PDMS)-based silicone implants in an effort to minimize capsular contracture. Two different surface modification strategies, namely, microtexturing as a physical cue and multilayer coating as a chemical cue, were combined to achieve synergistic effects. The deposition of uniformly sized microparticles onto uncured PDMS surfaces and the subsequent removal after curing generated microtextured surfaces with concave hemisphere micropatterns. The size of the individual micropattern was controlled by the microparticle size. Micropatterns of three different sizes (37.16, 70.22, and 97.64 μm) smaller than 100 μm were produced for potential application to smooth and round-shaped breast implants. The PDMS surface was further chemically modified by layer-by-layer (LbL) deposition of poly-l-lysine and hyaluronic acid. Short-term in vitro experiments demonstrated that all the PDMS samples were cytocompatible. However, lower expression of TGF-β and α-SMA, the major profibrotic cytokine and myofibroblast marker, respectively, was observed in only multilayer-coated PDMS samples with larger size micropatterns (70.22 and 97.64 μm), thereby confirming the synergistic effects of physical and chemical cues. An in vivo study conducted for 8 weeks after implantation in rats also indicated that PDMS samples with larger size micropatterns and multilayer coating most effectively inhibited capsular contracture based on analyses of tissue inflammation, number of macrophage, fibroblast and myofibroblast, TGF-β expression, collagen density, and capsule thickness. Statement of SignificanceAlthough poly(dimethylsiloxane) (PDMS)-based silicone implants have been widely used for various applications including breast implants, they usually cause typical side effects called as capsular contracture. Prior studies have shown that microtexturing and surface coating could reduce capsular contracture. However, previous methods are limited in their scope for application, and it is difficult to obtain FDA approval because of the large and nonuniform size of the microtexture as well as the use of toxic chemical components. Herein, those issues could be addressed by creating a microtexture of size less than 100 m, with a narrow size distribution and using layer-by-layer deposition of a biocompatible polymer without using any toxic compounds. Furthermore, this is the first attempt to combine microtexture with multilayer coating to obtain synergetic effects in minimizing the capsular contracture.

Improved the light extraction efficiency of GaN vertical light-emitting diodes using 3D sphere-like arrays

The formation of the micro-patterned structure in the vertical light-emitting diodes (VLEDs) is a practicable solution for light extraction enhancement. In this study, the Monte Carlo ray tracing method was used to investigate the effects of the absorption coefficient of GaN material and structural parameters of 3D sphere-like arrays on the light extraction efficiency (LEE). The simulation results showed that a maximum LEE change of about 17 % can be achieved when the absorption coefficient (α) varies between 0 and to 10 mm−1. The 3D sphere-like arrays can effectively improve the LEE of GaN VLEDs. The LEE decreases as the period of the 3D sphere-like arrays increases. The LEE for close-packed convex hemisphere arrays with R = 3 μm and α = 0/mm−1 is about 4.5 times greater than that for planar VLEDs. For the close-packed convex hemisphere arrays, the LEE of the GaN VLEDs is inversely correlated with their diameter. However, for the close-packed concave hemisphere arrays, an opposite trend was observed. In addition, for the VLEDs with the concave sphere-like arrays, an increase in array height leads to an improved LEE. These results provide theoretical guideline for the design of the GaN VLEDs with high LEE.

Test Particle Monte Carlo Simulation of Return Flux on Various Geometric Surfaces due to Ambient Scatter of Outgassing Molecules

The test particle Monte Carlo (TPMC) method is delineated by taking the molecular return flux problem for the flow past a complete sphere as an example and the return flux on a variety of geometric surfaces, including a complete sphere, a circle flat plate, a convex and concave hemisphere, due to ambient scatter of outgassing molecules is simulated by this method. The return flux ratio (RFR) obtained here for the flow past a sphere is in good agreement with previous results. Then, effects of various outgassing and freestream conditions on RFR for flows past three geometric bodies, including a circle flat plate, a convex and concave hemisphere, have been investigated and compared. Moreover, heuristic arguments about geometric, outgassing and freestream governing parameters provide theoretical references for the evaluation and control of return flux contamination.

Test Particle Monte Carlo Simulation of Return Flux on Various geometric surfaces due to Ambient Scatter of Outgassing Molecules

The test particle Monte Carlo (TPMC) method is delineated by taking the molecular return flux problem for the flow past a complete sphere as an example and the return flux on a variety of geometric surfaces, including a complete sphere, a circle flat plate, a convex and concave hemisphere, due to ambient scatter of outgassing molecules is simulated by this method. The return flux ratio (RFR) obtained here for the flow past a sphere is in good agreement with previous results. Then, effects of various outgassing and freestream conditions on RFR for flows past three geometric bodies, including a circle flat plate, a convex and concave hemisphere, have been investigated and compared. Moreover, heuristic arguments about geometric, outgassing and freestream governing parameters provide theoretical references for the evaluation and control of return flux contamination.

Surfactant-induced ordering and wetting transitions of droplets of thermotropic liquid crystals "caged" inside partially filled polymeric capsules.

We report a study of the wetting and ordering of thermotropic liquid crystal (LC) droplets that are trapped (or “caged”) within micrometer-sized cationic polymeric microcapsules dispersed in aqueous solutions of surfactants. When they were initially dispersed in water, we observed caged, nearly spherical droplets of E7, a nematic LC mixture, to occupy ∼40% of the interior volume of the polymeric capsules [diameter of 6.7 ± 0.3 μm, formed via covalent layer-by-layer assembly of branched polyethylenimine and poly(2-vinyl-4,4-dimethylazlactone)] and to contact the interior surface of the capsule wall at an angle of ∼157 ± 11°. The internal ordering of LC within the droplets corresponded to the so-called bipolar configuration (distorted by contact with the capsule walls). While the effects of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) on the internal ordering of “free” LC droplets are similar, we observed the two surfactants to trigger strikingly different wetting and configurational transitions when LC droplets were caged within polymeric capsules. Specifically, upon addition of SDS to the aqueous phase, we observed the contact angles (θ) of caged LC on the interior surface of the capsule to decrease, resulting in a progression of complex droplet shapes, including lenses (θ ≈ 130 ± 10°), hemispheres (θ ≈ 89 ± 5°), and concave hemispheres (θ < 85°). The wetting transitions induced by SDS also resulted in changes in the internal ordering of the LC to yield states topologically equivalent to axial and radial configurations. Although topologically equivalent to free droplets, the contributions that surface anchoring, LC elasticity, and topological defects make to the free energy of caged LC droplets differ from those of free droplets. Overall, these results and others reported herein lead us to conclude that caged LC droplets offer a platform for new designs of LC-droplet-based responsive soft matter that cannot be realized in dispersions of free droplets.

The Use of Augment Devices in Revision Acetabular Surgery.

As the number of total hip arthroplasties performed in the United States increases, and as more young patients undergo this procedure, it can be expected that the number of revision hip arthroplasties will also increase. Most acetabular revisions can be performed with a hemispherical shell. Results with these components show a rate of survivorship free of aseptic loosening of 97% (range, 94% to 100%) in 729 revision surgeries1-9 at a mean follow-up time of 9.8 years (range, six to 21.3 years). Use of a hemispherical shell requires the creation of a supportive, concave hemisphere of bone. While in the majority of acetabular revisions this goal is attainable, at times the nature of the acetabular osseous defect makes this goal unobtainable. This can be understood as the inability to ream a large enough hemisphere, with the goal of reaching the apex of the superior aspect of the deformity, without in the process removing supportive anterior and posterior host bone. In this setting, an oblong osseous deficiency is left over (defined as the superior to inferior length of the overall defect being greater than the anterior to posterior width of the remaining …

N‐GaN column arrays on the vertical InGaN/GaN blue LEDs formed by maskless dry etching

The InGaN/GaN blue light emitting diodes (LED) structures have been grown on sapphire substrates with a hexagonal array of hemispherical patterns by low‐pressure metalorganic chemical vapor deposition. Vertical LED structures on Cu carriers are fabricated using electroplating and KrF laser lift‐off techniques. After removal of the patterned sapphire substrate, an inductively coupled plasma etching is carried out to expose the n‐GaN layer for n‐metal contact. It is observed that GaN columns are formed at the center of the concave hemispheres after dry etching processes. Cathodoluminescence and wet chemical etching investigations reveal that a high density of dislocations is found to be generated at these specific positions. The possible mechanism for these observations is attributed to the defect distribution and defect‐dependent selective etching of the GaN.

GaN-based light-emitting diodes by laser lift-off with micro- and nano-sized reflectors

GaN-based light-emitting diodes (LEDs) were grown on a patterned sapphire substrate (PSS) containing hemispheres on the growth surface. Free-standing LED structures were obtained by removing the PSS using laser lift-off technique. The N-face GaN surface with micron-sized concave hemisphere structures, which had been located between the sapphire and the GaN film, was then exposed and photo-electrochemically etched using a 2M KOH solution to create nano-sized pyramids. Aluminum was deposited on the roughened N-face GaN as a reflective layer. The roughened aluminum reflectors, consisting of micron-sized hemisphere structures and nano-sized pyramids, enhanced the light extraction efficiency through multiple scattering events of photons and randomized the directions of the photons. The subsequent enhancement in electroluminescence was 13% compared with an untextured control LED.

LES of Impingement Heat Transfer on a Concave Surface

Wall-resolved and zonal numerical large eddy type simulations are performed for a round jet impinging on a concave hemisphere at Re = 23,000. The zonal method uses a near-wall k–l model and a Hamilton-Jacobi equation to match this to the large eddy simulation zone. To minimize numerical dissipation, a self-adaptive discretization (SDS) scheme is examined. Both second- (n = 2) and sixth- (n = 6) order-based central discretization schemes are tested. The characteristics of the schemes is assessed using two test cases: the development of a subcritical Tollmien-Schlichting (T-S) stability wave in a plane channel and the decay of homogenous, isotropic turbulence (DHIT). It is found, that Smagorinsky LES simulations tend to be too dissipative in the high wave-number region, even with the SDS scheme; hence, the SGS model is omitted. Significant flow feedback is observed for the hemisphere case. Both shear-layer excitation and stabilization is observed. Computed wall pressure coefficients for the zonal NLES method are encouraging; for the wall-resolved case the stagnation region value is overpredicted. Heat transfer for the wall-resolved and zonal large eddy simulations are encouraging. For both quantities the difference between the n = 2 and n = 6 schemes is small, and the modeling approach used appears to be more influential. It is concluded that the presence of feedback mechanisms should be considered when designing experiments and/or numerical simulations for this case, and that the importance of boundary conditions for LES should not be neglected.

Enhanced Light Extraction in GaN-Based Light-Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium–Tin-Oxide Layer

The enhanced light extraction of the GaN-based light-emitting diode (LED) with a two-dimensional concave hemisphere-shaped indium–tin-oxide (ITO) layer, fabricated using laser holographic lithography and inductively-coupled plasma etching techniques were studied. Compared to the LED with a planar ITO layer, it is found that the light output power of LEDs with concave hemisphere patterned ITO layers is improved by ∼34%. This enhanced light output power is attributed to the increase of light extraction by effective photon escape and self-divergence effect at the concave hemisphere-shaped ITO surface.

The representation of moving 3-D objects in apparent motion perception

In the present research, we investigated the depth information contained in the representations of apparently moving 3-D objects. By conducting three experiments, we measured the magnitude of representational momentum (RM) as an index of the consistency of an object's representation. Experiment 1A revealed that RM magnitude was greater when shaded, convex, apparently moving objects shifted to a flat circle than when they shifted to a shaded, concave, hemisphere. The difference diminished when the apparently moving objects were concave hemispheres (Experiment 1B). Using luminance-polarized circles, Experiment 2 confirmed that these results were not due to the luminance information of shading. Experiment 3 demonstrated that RM magnitude was greater when convex apparently moving objects shifted to particular blurred convex hemispheres with low-pass filtering than when they shifted to concave hemispheres. These results suggest that the internal object's representation in apparent motion contains incomplete depth information intermediate between that of 2-D and 3-D objects, particularly with regard to convexity information with low-spatial-frequency components.

GaN-Based Light-Emitting Diode With Three-Dimensional Silver Reflectors

We present a simple and robust method to fabricate three-dimensional Ag reflectors on GaN light-emitting diodes (LEDs) using SiO 2 nanospheres as the template. First, the hexagonal arrays of SiO2 nanosphere monolayer were spun-cast on a benzocyclobutene (BCB) layer, which was prepared on a sapphire surface. Then, the bottom half of the SiO2 nanospheres were embedded into the BCB layer after heating, resulting in arrays of ldquonano-lensesrdquo that were in the shape of convex hemispheres. The concave-shaped hemisphere arrays were produced by etching the SiO2 nanospheres with an HF solution. Ag was deposited onto both patterns, concave and convex hemispheres, resulting in the formation of three-dimensional Ag reflectors. From the electroluminescence measurements, these Ag reflectors, which contained either concave or convex hemisphere patterns, were found to enhance the light output of GaN LEDs by as much as 29%-33%.

Structural determinants of monohydroxylated bile acids to activate β1 subunit-containing BK channels

Lithocholate (LC) (10-300 microM) in physiological solution is sensed by vascular myocyte large conductance, calcium- and voltage-gated potassium (BK) channel beta(1) accessory subunits, leading to channel activation and arterial dilation. However, the structural features in steroid and target that determine LC action are unknown. We tested LC and close analogs on BK channel (pore-forming cbv1+beta(1) subunits) activity using the product of the number of functional ion channels in the membrane patch (N) and the open channel probability (Po). LC (5beta-cholanic acid-3alpha-ol), 5alpha-cholanic acid-3alpha-ol, and 5beta-cholanic acid-3beta-ol increased NPo (EC(50) approximately 45 microM). At maximal increase in NPo, LC increased NPo by 180%, whereas 5alpha-cholanic acid-3alpha-ol and 5beta-cholanic acid-3beta-ol raised NPo by 40%. Thus, the alpha-hydroxyl and the cis A-B ring junction are both required for robust channel potentiation. Lacking both features, 5alpha-cholanic acid-3beta-ol and 5-cholenic acid-3beta-ol were inactive. Three-dimensional structures show that only LC displays a bean shape with clear-cut convex and concave hemispheres; 5alpha-cholanic acid-3alpha-ol and 5beta-cholanic acid-3beta-ol partially matched LC shape, and 5alpha-cholanic acid-3beta-ol and 5-cholenic acid-3beta-ol did not. Increasing polarity in steroid rings (5beta-cholanic acid-3alpha-sulfate) or reducing polarity in lateral chain (5beta-cholanic acid 3alpha-ol methyl ester) rendered poorly active compounds, consistent with steroid insertion between beta(1) and bilayer lipids, with the steroid-charged tail near the aqueous phase. Molecular dynamics identified two regions in beta(1) transmembrane domain 2 that meet unique requirements for bonding with the LC concave hemisphere, where the steroid functional groups are located.

My First 10 Years as Artist/Holographer (1968-1977)

but structured patterns, reminiscent of Constructivist art, though my philosophy is unlike that of Constructivism [9]. Ultimately, Holos 17 (1973), a laser transmission hologram (Fig. 3), was the result. A concave hemisphere recorded in the first exposure was turned around in the darkness between exposures so that it became a convex hemisphere. When recorded in the second exposure, the convex hemisphere met the light pattern of the concave hemisphere, whereupon we had a complete sphere, not outlined as such but formed by its own laser light pattern. We intended to use the laser transmission holograms as exhibition pieces, with the best of them as masters for white-light transmission imagery that would project frontally. Although segments of the H 1 (master) pseudoscopic design could be seen from a distance of approximately 30 ft, which I found tantalizing (and have shown this way), the total HI image was too large to emerge through the H2 plates to be seen easily at a moderate distance. Furthermore, the second-generation white-light holograms seemed to have unfathomable problems other than size. After much searching, it was finally determined that the emulsion on the secondgeneration plates was defective (we had been using Agfa-Gevaert 8E75; as all holographers know, it is not unusual to receive a batch of plates with imperfect emulsion). Since we had to redo the H2s, we put Fig. 4. Equivocal Forks I, laser transmission hologram, plate 11x 14 in, pseudoscopic image projecting in front of the plate = 24 to 30 in, 1977. (Photo: Nisham Bichajian) Using a cluster of forks as the object, I placed much effort in the frontally projected imagery so that the glass would not be an obstruc-

General design of two-reflector antennas

A new description of the profiles of the main reflector and subreflector of a dual-reflector antenna is given in terms of a single parameter, the angle subtended by the normal to the main reflector and the axis of the system. It is shown that the same parameter describes the nature of the focusing in both the illuminating beam and the image space. Hence, quite general illumination, focusing and main reflector profiles can be considered. The results are illustrated for subreflectors in the concave hemisphere and paraboloid, for axial illumination and offset conditions, and the application of the method to amplitude shaping or the Abbe sine condition is discussed.