Combination Of Photo Research Articles

Combined photo- and electroreflectance of multijunction solar cells enabled by subcell electric coupling

Electric coupling between subcells of a monolithically grown multijunction solar cell in short circuit allows their simultaneous and independent characterization by means of photo- and electro-reflectance. The photovoltage generated by selective absorption of the pump beam in a given subcell during photoreflectance measurements results in reverse biasing the complementary subunits at the modulation frequency set on the pump illumination. Such voltage bias modulation then acts as external perturbation on the complementary subcells. The spectral separation of different subcell absorption ranges permits the probe beam to record in a single spectrum the response of the complete device as a combination of photo- and electro-reflectance, thereby providing access for the diagnosis of subcells on an individual basis. This form of modulation spectroscopy is demonstrated on a GaInP/GaAs tandem solar cell.

Video art of Lviv, late XX - early XXI century, historical context: creating an art form

Background. For the last 25 years videoart in Ukraine had passed a maturation from the elementary experimental video practices of the end of the 80's to the full-identical art form. Like most of the USSR innovative art trends, videoart in Ukraine paved it's way through the formal endorsement's resistance and had been creating owing to the enthusiasm and persistence of individual artists and single artistic formations. Ukrainian videoart had developed according to all the fine art growth's features of socialistic period; however was established and concepted for the first time in Lviv as a phenomenon in the 1990-s what had generated a brand-new pleiad of cultural actors and had influence on the alternative artistic expression mediums of that time. Objectives. The incipience and developnent of Lviv videoart appears to be the main goal, applicating specifics of the new media style in individual artistic identification for single artists and Lviv artistic enviroment in general; reconstitution of the expression of new visual ideas made via video camera among social and historical “perestroika” context. Videoart role definition in the artistic expression of the totalitarian unrest period. Methods. Achieving the goals of the article was implemented via empirical methods: comparison, observation, description of the historical facts, which preceded videoart foundation throughout Ukraine. Theoretical methods were founded for the analysis of videoart, it’s role and position in art studies historiography of Lviv focus. Also deductive chronology playbacking method, what gave an opportunity to represent a whole artistic climate where Lviv videoart was established. Classification method divided artistic formations into groups based on artistic and stylistic criterion. Results. The research results confirmed the idea of independent Lviv videoart existance with it’s own establishing and development history. Research, based on Andrij Boyarov artworks of the end of 80’s, showed up comprehensive data that videoart had not been positioned as additional medium for single artist’s creations diluting; combination of photo and video was and remains the main activity for a certain range of artists thus proving that emergence of videoart genre had not turned into spontaneous way or copied from West European processes but rather appeared to be totally required by socio-political environment, the artist and the viewer to see the video reflections in galleries. Formed chronology showed up a special linkages between the appearance of brand-new art experiments, alternative practices and youth movements, festivals and artistic formations that had established the very first Ukrainian galleries and had placed curator practices unprecedented neither for artists nor for viewers. These were the “Tsenter Europy”, “Try Krapky”, “Dzyga” galleries, where the exhibitions “Thing Theatre or thing ecology”, “Defloration” and “Congress of Ukrainian Physicians Exhibition” took place at the time of turning point of Ukraine’s 90’s. The “Vyvykh” Festival had become a so-called Vesuvius for massive Lviv non-conformism vector, which explored a number of brand-new names of experimental art and videoart: Alfred Maksymenko, Andrij Boyarov, Hanna Kuts, Viktor Dovhaljuk, Ihor Podolchak, Serhiy Petljuk and others. During the consideration it was revealed that Lviv videoart meant to be different from the one in the other Ukrainian videoart centers due to it “pedagogical” aspect, namely it was the only center, where the experience sharing for the young generation truly existed, that had been caused by reservation problem and communication absence between the videoartists and a range of author generations. The originator of the first videoart in Ukraine - Alfred Maksymenko - now works as a pedagogue at Lviv National Academy of Arts, whose Studies generated a number of videoartists, carring on Lviv Classic School traditions and creating original stylistic indications. Conclusions. This social-informational research has shown preconditions for a brand-new art genre establishment - the 90’s Lviv videoart and the fact that it was not born in a way of “playing” or “flirtation” with some kind of new imported technical equipment but had it’s own conceptual way instead; got an opportunity to continue previous visual practices and expand the frontiers of visual influences on viewer. The analysis of Lviv videoart formation concludes the research and brings up the subject for further researches: establishing of high-quality art analysis of single artists working in videoart for already more than 25 years. A totally special stylistic manner of creating video images had emerged during that time period, which echoes with traditional Lviv Classic School painting manner and brand-new mediums born and dictated by alternative angles and technical implementation of videoart.

‘A little good with the bad’: Newly diagnosed type 2 diabetes patients’ perspectives on self-care: A phenomenological approach

Increased knowledge is needed about what self-care means from the patients’ perspective, especially since the patient population with type 2 diabetes has been rising. The aim was to describe self-care, as experienced by patients with newly diagnosed type 2 diabetes. This study adopted a phenomenological approach. Eight patients were interviewed. A combination of photos and interviews were used. The essential meaning of self-care was found to be an existential struggle that evokes feelings of being in-between one’s old unhealthy life and a new healthier one. In this in-between condition, tension exits between contradictorily emotions of anxiety, hopelessness and hope. This struggle also means questioning one’s identity. It is important that diabetes nurses create an opening for reflection and dare to challenge their patients to reflect on this existential struggle.

Scattered Mosaic Rendering Using Unit Images

An image mosaic method that can be used when creating advertisements or posters is proposed in this study. Mosaic is a method that expresses an entire image using an arbitrary number of cells. Photomosaic generates new images using a combination of photos. In this paper, we propose a new mosaic algorithm that generates an abstract artistic mosaic image by filling a region that is divided by a boundary using a unit image, which is an image that only has a shape and no allocated color. A unit image can be changed diversely through rotation or shifting, and the corresponding region is filled by using the gradient direction and edge information of the input image. For this, we extract and use information from input image such as color, edge and gradient. In result we can generate various abstractive images which can be used in advertisement and multimedia contents market.

A poly(glycerol sebacate) based photo/thermo dual curable biodegradable and biocompatible polymer for biomedical applications

Due to its biomimetic mechanical properties to soft tissues, excellent biocompatibility and biodegradability, poly (glycerol sebacate) (PGS) has emerged as a representative bioelastomer and been widely used in biomedical engineering. However, the typical curing of PGS needs high temperature (>120 °C), high vacuum (>1 Torr), and long duration (>12 h), which limit its further applications. Accordingly, we designed, synthesized and characterized a photo/thermo dual curable polymer based on PGS. Treatment of PGS with 2-isocyanatoethyl methacrylate without additional reagents readily produced a methacrylated PGS (PGS-IM). Photo-curing of PGS-IM for 10 min at room temperature using salt leaching method efficiently produced porous scaffolds with a thickness up to 1 mm. PGS-IM was adapt to thermo-curing as well. The combination of photo and thermo curing provided a further way to modulate the properties of resultant porous scaffolds. Interestingly, photo-cured scaffolds exhibited hierarchical porous structures carrying extensive micropores with a diameter from several to hundreds micrometers. All the scaffolds showed good elasticity and biodegradability. In addition, PGS-IM exhibited good compatibility with L929 fibroblast cells. We expect this new PGS based biomaterial will have a wide range of biomedical applications.

Multicatalytic, Light-Driven Upgrading of Butanol to 2-Ethylhexenal and Hydrogen under Mild Aqueous Conditions.

Microbes produce low-molecular-weight alcohols from sugar, but these metabolites are difficult to separate from water and possess relatively low heating values. A combination of photo-, organo-, and enzyme catalysis is shown here to convert C4 butanol (BuOH) to C8 2-ethylhexenal (2-EH) using only solar energy to drive the process. First, alcohol dehydrogenase (ADH) catalyzed the oxidation of BuOH to butyraldehyde (BA), using NAD+ as a cofactor. To prevent back reaction, NAD+ was regenerated using a platinum-seeded cadmium sulfide (Pt@CdS) photocatalyst. An amine-based organocatalyst then upgraded BA to 2-EH under mild aqueous conditions rather than harsh basic conditions in order to preserve enzyme and photocatalyst stability. The process also simultaneously increased total BuOH conversion. Thus, three disparate types of catalysts synergistically generated C8 products from C4 alcohols under green chemistry conditions of neutral pH, low temperature, and pressure.

Controlled Release of Small Molecules from Elastomers for Reducing Epidermal Downgrowth in Percutaneous Devices.

The elevated infection rise associated with indwelling devices can compromise the performance of percutaneous devices and increase the risk of complications. High infection rates are associated with both the high bacterial load on the skin and epidermal downgrowth at the interface of the indwelling material. Here, we propose a drug-eluting material that promotes local dermal regeneration to reduce epidermal downgrowth. Mesoporous elastomeric matrices composed of naturally occurring monomers were prepared by a combination of photo- and thermal-crosslinking. Elastomeric devices loaded with conjugated linoleic acids (CLA), a class of small molecules that promote local anti-inflammatory responses, can deliver these compounds for 7 d (DCLA-elastomer = 3.94 × 10-9 cm2/s, 95% CI [3.12 × 10-9, 4.61 × 10-9]). In a mouse model, CLA-eluting elastomeric matrices increase the M2 population (5.0 × 103 ± 1.4 × 103 cells/cm2), compared to blank devices (3.8 × 103 ± 2.2 × 103 cells/cm2), and also reduce skin contraction (98.9 ± 6.4%), compared to blank devices (70.9 ± 9.3%) at 7 d. Dermal downgrowth is also attenuated at 14 d (60.4 ± 32.4 μm) compared to blank devices (171.7 ± 93.8 μm). CLA-eluting elastomers are therefore a viable strategy to reduce epidermal downgrowth in percutaneous devices.

Sessile and mobile components of a benthic ecosystem display mixed trends within a temperate marine reserve

Despite recent efforts to increase the global coverage of marine protected areas (MPAs), studies investigating the effectiveness of marine protected areas within temperate waters remain scarce. Furthermore, out of the few studies published on MPAs in temperate waters, the majority focus on specific ecological or fishery components rather than investigating the ecosystem as a whole. This study therefore investigated the dynamics of both benthic communities and fish populations within a recently established, fully protected marine reserve in Lamlash Bay, Isle of Arran, United Kingdom, over a four year period. A combination of photo and diver surveys revealed live maerl (Phymatolithon calcareum), macroalgae, sponges, hydroids, feather stars and eyelash worms (Myxicola infundibulum) to be significantly more abundant within the marine reserve than on surrounding fishing grounds. Likewise, the overall composition of epifaunal communities in and outside the reserve was significantly different. Both results are consistent with the hypothesis that protecting areas from fishing can encourage seafloor habitats to recover. In addition, the greater abundance of complex habitats within the reserve appeared to providing nursery habitat for juvenile cod (Gadus morhua) and scallops (Pecten maximus and Aequipecten opercularis). In contrast, there was little difference in the abundance of mobile benthic fauna, such as crabs and starfish, between the reserve and outside. Similarly, the use of baited underwater video cameras revealed no difference in the abundance and size of fish between the reserve and outside. Limited recovery of these ecosystem components may be due to the relatively small size (2.67 km2) and young age of the reserve (<5 years), both of which might have limited the extent of any benefits afforded to mobile fauna and fish communities. Overall, this study provides evidence that fully protected marine reserves can encourage seafloor habitats to recover, which in turn, can create a number of benefits that flow back to other species, including those of commercial importance.

Enhanced Visible-Light Photoactivity of CuWO4 through a Surface-Deposited CuO

Several papers have shown that CuWO4 is active under visible light for water oxidation at an applied potential bias and for organic degradation in an aerated aqueous suspension. In this work, we report that the observed reduction of O2 on the irradiated CuWO4 is a multielectron transfer process with the formation of H2O2. More importantly, the surface modification of CuWO4 with 1.8 wt % of CuO can increase the activity by approximately 9 times under UV light and by 5 times under visible light, for phenol degradation in aerated aqueous suspension. The catalyst was prepared by a hydrothermal reaction between Cu(NO3)2 and Na2WO4, followed by thermal treatment at 773 K. High-resolution transmission electron microscopy revealed that triclinic CuWO4 (40 nm) was covered by monoclinic CuO (4 nm). Through a combination of photo- and electrochemical measurement, a plausible mechanism responsible for the activity enhancement is proposed, involving an interfacial electron transfer from CuO to CuWO4 and an interfacial...

Planar integrated plasmonic mid-IR spectrometer

ABSTRACTA compact spectrometer-on-a-chip featuring a plasmonic molecular interaction region has been conceived, designed, modeled, and partially fabricated. The silicon-on-insulator (SOI) system is the chosen platform for the integration. The low loss of both silicon and SiO2 between 3 and 4 μm wavelengths enables silicon waveguides on SiO2 as the basis for molecular sensors at these wavelengths. Important characteristic molecular vibrations occur in this range, namely the bond stretching modes C-H (Alkynes), O-H (monomeric alcohols, phenols) and N-H (Amines), as well as CO double bonds, NH2, and CN. The device consists of a broad-band infrared LED, photonic waveguides, photon-to-plasmon transformers, a molecular interaction region, dispersive structures, and detectors. Photonic waveguide modes are adiabatically converted into SPPs on a neighboring metal surface by a tapered waveguide. The plasmonic interaction region enhances optical intensity, which allows a reduction of the overall device size without a reduction of the interaction length, in comparison to ordinary optical methods. After the SPPs propagate through the interaction region, they are converted back into photonic waveguide modes by a second taper. The dispersing region consists of a series of micro-ring resonators with photodetectors coupled to each resonator. Design parameters were optimized via electro-dynamic simulations. Fabrication was performed using a combination of photo- and electron-beam-lithography together with standard silicon processing techniques.

Endothelial cell adhesion and growth within a bioassay chamber using microstamped ECM proteins

Our goal was to evaluate microvascular endothelial cell growth on microstamped patterns of extracellular matrix proteins (ECM). A combination of photo- and soft-lithography was used to make features ∼100 μm deep and 150μm wide. Polydimethylsiloxane imprints of features produced positive molds used to stamp collagen I, IV, laminin and fibronectin onto cleaned hydrophilic or hydrophobic glass coverslips. Human dermal microvascular endothelial cells were seeded at an initial density of 800 cells cm-2, and cultured for three days. Explanted murine aortas, serving as an initial source for autologous endothelial cells, were perfused at 240 μL min−1 for 1 day. Cell morphology was also quantified on both the non-patterned glass and within the microstamped patterns. Viability was high (>90%) on all microstamped proteins, regardless of glass hydrophobicity. Viability was reduced on bare hydrophobic glass. Cell density was 4 or 8 fold higher on microstamped ECM proteins compared with hydrophilic or hydrophobic glass, respectively. Confluence was approached more rapidly on microstamped proteins. Thus, rapid concentrated growth of endothelial cells was markedly enhanced within microstamped ECM patterns on hydrophilic and hydrophobic glass.

EPR Simulation of Polyenyl Radicals in Ultrahigh Molecular Weight Polyethylene

An irradiated polyethylene sample containing mostly dienyl free radicals was fabricated by using a combination of photo and thermal treatments. This allowed, for the first time, unambiguous observation of the dienyl radical’s EPR signal to be a singlet with eight hyperfine peaks 9 G apart. Accurate simulation parameters for the dienyl radical were determined. While inaccurate for the dienyl radical, the assumption that a smooth singlet can simulate polyenyl radicals holds true for higher-order polyenyl radicals. The line width of the polyenyl singlet is a function of the radical’s location, with the line width decreasing as the surrounding morphology becomes more organized and uniform, as is the case in the crystalline region. The decreasing line width of polyenyl spectra after exposure to air suggests that the rate of oxidatively induced crystallization is more rapid than oxygen diffusion within the polymer.

Ati-atihan: Mother of Philippine Festivals

Ati-atihan: Mother of Philippine Festivals

Nonbiofouling Polymer Brush with Latent Aldehyde Functionality as a Template for Protein Micropatterning

A novel, nonfouling polymer brush, poly-N-[(2,3-dihydroxypropyl)acrylamide] (PDHPA), containing latent aldehyde groups, was synthesized by surface initiated atom transfer radical polymerization (SI-ATRP). The synthetic parameters were adjusted to produce brushes with varying graft densities and molecular weights. High-density PDHPA brushes successfully prevented the nonspecific protein adsorption from single protein solutions as well as from human platelet poor plasma. Patterns of nonfouling PDHPA and reactive PDHPA-aldehyde domains on the brush surface were created by a combination of photo and wet chemical lithography from a single homogeneous PDHPA brush. Successful micropatterning of single proteins and multiple proteins were achieved using this novel substrate. The high-density brush prevented the diffusion of large proteins into the brush, while a monolayer of covalently coupled proteins was formed on the PDHPA-aldehyde domains. Atomic force microscopy (AFM) force measurements using a biotin coupled AFM tip showed that covalently coupled streptavidin retained its activity, while PDHPA domains showed little nonspecific adsorption of streptavidin. The current study avoids tedious and complicated synthetic processes employed in conventional approaches by providing a novel approach to protein micropatterning from a single, multifunctional polymer brush.

Micro‐stamped ECM proteins enhance endothelial cell adhesion and directed growth

Our goal was to evaluate microvascular endothelial cell growth within micro-stamped patterns of extracellular matrix proteins (ECM). A combination of photo- and soft-lithography was used. Features ~100μm deep and 50–150μm wide were fabricated from SU-8 2100 photoresist. Polydimethylsiloxane imprints of features produced positive molds used to stamp extracellular matrix proteins (collagen I, IV, or laminin each at 5μg/mm2; fibronectin at 3.4μg/mm2) onto cleaned glass coverslips (n = 4 each). ECM was allowed to dry; the average stamp width was ~160μm, measured prior to cell seeding. Human dermal microvascular endothelial cells (ECs) were seeded at an initial density of 800 cells/cm2, and cultured for three days. We hypothesized that by day 3, ECs would have higher viability and density on the patterned matrices vs. on bare glass. On day 3, there were clearly visible bands of cells growing throughout the patterned matrices (~150–300μm wide). Cells were stained with calcein/ethidum and imaged to obtain viability and density on either the untreated bare glass, or along the stamped patterns. Cell viability was high (>90%) for all conditions independent of location, and was >95% along collagen I and fibronectin stamped patterns. Cell density increased by 4-fold on glass (3,472±1,179 cells/cm2, mean±SD) and up to 16-fold on the micro-stamped proteins (fibronectin, 17,545±7,892; collagen IV, 15,381±7,031; collagen I, 12,498±8,583; laminin, 9,511±4,333 cells/cm2). Thus, concentrated growth of ECs was markedly enhanced within micro-stamped ECM patterns suggesting either enhanced adhesion or proliferation. (NIH HL55492)

Optimized technology for freely positionable Josephson junctions in YBa/sub 2/Cu/sub 3/O/sub 7-x/ fabricated by local ion damaging

Freely positionable Josephson junctions in high-temperature superconductor thin films are fabricated by a combination of photo- and electron-beam lithography. In selected regions of YBCO thin films point defects are induced by oxygen implantation. These weak links exhibit resistively shunted junction (RSJ)-like voltage-current characteristics close to the junction transition-temperature. Below this temperature, a transition from RSJ to flux-flow behavior is observed. Fraunhofer patterns appear in magnetic modulation measurements at different temperatures. The temperature dependence of the critical current reveals superconductor/normal conductor/superconductor (SNS) features. The dependence of Shapiro steps on microwave power demonstrates Josephson contributions over the entire temperature range.