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Ebuka S Arinze, Botong Qiu, Nathan Palmquist, Yan Cheng, Yida Lin, Gabrielle Nyirjesy, Gary Qian, Susanna M Thon
Colloidal quantum dots (CQDs), are a promising candidate material for realizing colored and semitransparent solar cells, due to their band gap tunability, near infrared responsivity and solution-based processing flexibility. CQD solar cells are typically comprised of several optically thin active and electrode layers that are optimized for their electrical properties; however, their spectral tunability beyond the absorption onset of the CQD layer itself has been relatively unexplored. In this study, we design, optimize and fabricate multicolored and transparent CQD devices by means of thin film interference engineering...
February 20, 2017: Optics Express
Jianwei Chen, Hiu Hung Lee, Dongping Wang, Si Di, Shih-Chi Chen
We present a high-precision hybrid imprinting method to fabricate multi-layer micro-optical structures on nonplanar substrates using a custom-built vacuum imprinting system; with the application of kinematic couplings that align the flexible stamps in all six degrees of freedom, a cross-layer pattern registration precision of 400 nm has been achieved on nonplanar substrates. To demonstrate the precision and feasibility of the new process and instrument, we have designed and fabricated a multi-layer artificial compound eye (ACE) for multispectral imaging...
February 20, 2017: Optics Express
Stacy J Kowsz, Erin C Young, Benjamin P Yonkee, Christopher D Pynn, Robert M Farrell, James S Speck, Steven P DenBaars, Shuji Nakamura
We report a device that monolithically integrates optically pumped (20-21) III-nitride quantum wells (QWs) with 560 nm emission on top of electrically injected QWs with 450 nm emission. The higher temperature growth of the blue light-emitting diode (LED) was performed first, which prevented thermal damage to the higher indium content InGaN of the optically pumped QWs. A tunnel junction (TJ) was incorporated between the optically pumped and electrically injected QWs; this TJ enabled current spreading in the buried LED...
February 20, 2017: Optics Express
Monika Dabrzalska, Anna Janaszewska, Maria Zablocka, Serge Mignani, Jean Pierre Majoral, Barbara Klajnert-Maculewicz
The efficiency of photodynamic therapy is limited mainly due to low selectivity, unfavorable biodistribution of photosensitizers, and long-lasting skin sensitivity to light. However, drug delivery systems based on nanoparticles may overcome the limitations mentioned above. Among others, dendrimers are particularly attractive as carriers, because of their globular architecture and high loading capacity. The goal of the study was to check whether an anionic phosphorus dendrimer is suitable as a carrier of a photosensitizer-methylene blue (MB)...
February 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Jolanta Lisowska, Lukasz Lisowski, Carina Kelbsch, Fumiatsu Maeda, Paul Richter, Susanne Kohl, Ditta Zobor, Torsten Strasser, Krunoslav Stingl, Eberhart Zrenner, Tobias Peters, Helmut Wilhelm, M Dominik Fischer, Barbara Wilhelm
Purpose: To establish a feasible and sensitive pupillographic protocol to assess outer and inner retinal function for the first gene therapy trial in achromatopsia patients (ACHM) with mutations in CNGA3. Methods: Twenty-seven CNGA3-ACHM patients and 22 age-matched control subjects were tested using chromatic pupillography. Three different protocols were established to assess the pupillary light reflex parameters and to create the final protocol. In the individual protocols, various stimulus parameters (i...
February 1, 2017: Investigative Ophthalmology & Visual Science
Cody Ross Pitts, Maxime A Siegler, Thomas Lectka
An unprecedented intermolecular aliphatic C-F---H-C interaction was observed in the X-ray crystal structure of a fluorinated triterpenoid. Despite the notion of fluorine being a poor acceptor, computational and IR studies revealed this interaction to be a weak-moderate hydrogen bond with a C-H stretch vibration frequency blue shifted by 14 cm-1 and d(F-H) = 2.13 Å. What is more, the aliphatic C-F bond is the preferred acceptor in the presence of multiple, traditionally stronger oxygen-based hydrogen bond acceptors...
February 27, 2017: Journal of Organic Chemistry
Motoshi Kamiya, Shigehiko Hayashi
Rhodopsin is a G-protein coupled receptor functioning as a photoreceptor for vision through photoactivation of a covalently bound ligand of a retinal protonated Schiff base chromophore. Despite the availability of structural information on the inactivated and activated forms of the receptor, the transition processes initiated by the photoabsorption have not been well understood. Here we theoretically examined the photoactivation processes by means of molecular dynamics (MD) simulations and ab initio quantum mechanical/molecular mechanical (QM/MM) free energy geometry optimizations which enabled accurate geometry determination of the ligand molecule in ample statistical conformational samples of the protein...
February 27, 2017: Journal of Physical Chemistry. B
Stefano Canossa, Alessia Bacchi, Claudia Graiff, Paolo Pelagatti, Giovanni Predieri, Andrea Ienco, Gabriele Manca, Carlo Mealli
The aromatic methylene blue cation (MB(+)) shows unprecedented ligand behavior in the X-ray structures of the trigonal-planar (TP) complexes MBMCl2 (M = Cu(I), Ag(I)). The two isostructural compounds were exclusively synthesized by grinding together methylene blue chloride and MCl solids. Only in the case of AuCl did the technique lead to a different, yet isoformular, Au(I) derivative with separated MB(+) and AuCl2(-) counterions and no direct N-Au linkage. While the density functional theory (DFT) molecular modeling failed in reproducing the isolated Cu and Ag complexes, the solid-state program CRYSTAL satisfactorily provided for Cu the correct TP building block associated with a highly compact π stacking of the MB(+) ligands...
February 27, 2017: Inorganic Chemistry
Meysam Pazoki, T Jesper Jacobsson, Jolla Kullgren, Erik M J Johansson, Anders Hagfeldt, Gerrit Boschloo, Tomas Edvinsson
Organometallic halide perovskites (OMHPs) have recently emerged as a promising class of materials in photovoltaic technology. Here we present an in-depth investigation of the physics in these systems by measuring the photo-induced absorption (PIA) in OMHPs as a function of materials composition, excitation wavelength and modulation frequency. We report a photoinduced Stark effect that depends on the excitation wavelength and on the dipole strength of the monovalent cations in the A position of the ABX3 perovskite...
February 27, 2017: ACS Nano
Niraj Shenoy, Mary Stenson, Joshua Lawson, Jithma Abeykoon, Mrinal Patnaik, Xiaosheng Wu, Thomas Witzig
Cell viability assays such as Cell Titer Blue and Alamar Blue rely on the reducing property of viable cells to reduce the reagent dye to a product which gives a fluorescent signal. The current manufacture-recommended protocols do not take into account the possibility of the reagent substrate being reduced directly to the fluorescent product by drugs with an anti-oxidant property. After suspecting spurious results while determining the cytotoxic potential of a drug of interest (DOI) with known anti-oxidant property against a renal cell cancer (RCC) cell line, we aimed to establish that drugs with anti-oxidant property can indeed cause false-negative results with the current protocols of these assays by direct reduction of the reagent substrate...
February 27, 2017: Laboratory Investigation; a Journal of Technical Methods and Pathology
Umberto Giovanella, Elena Cariati, Elena Lucenti, Mariacecilia Pasini, Francesco Galeotti, Chiara Botta
A novel and versatile approach to tune photoluminescence and electroluminescence by in situ controlled thermal deprotonation is presented. This methodology, based on a single organic π-conjugated material (pyrene derivative), allows the manufacturing of Organic Light-Emitting Diodes (OLEDs) prototypes by solution methods with controlled tunable emission ranging from the orange (protonated form of the dye) to the blue (pristine or deprotonated form). While several protonation/deprotonation cycles can be performed on thin films, for the devices only one cycle is possible so that their use as anti-fraud labels can be envisaged...
February 27, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Mirjana Popadic, Christoph Sinz, Harald Kittler
BACKGROUND AND OBJECTIVES: Skin lesions with blue color are frequently excised to rule out malignancy. The objective of the present study was to investigate the significance of blue color. METHODS: We retrospectively scanned dermatoscopic images for blue color and classified them according to pattern analysis. RESULTS: Of 1,123 pigmented skin lesions, 144 (12.8 %) showed blue color, 92 of which (63.9 %) were malignant. Among lesions with blue color, the most common benign diagnoses were nevi (n = 35, 24...
February 27, 2017: Journal der Deutschen Dermatologischen Gesellschaft, Journal of the German Society of Dermatology: JDDG
Hugo Almeida, Paulo Lobão, Christian Frigerio, Joel Fonseca, Renata Silva, José Manuel Sousa Lobo, Maria Helena Amaral
CONTEXT: Nanostructured lipid carrier (NLC) dispersions present low viscosity and poor mucoadhesive properties, which reduce the pre-corneal residence time and consequently, the bioavailability of ocular drugs. OBJECTIVE: The aim of this study was to prepare thermoresponsive eyedrops based on the combination of lipid nanoparticles and a thermoresponsive polymer with mucomimetic properties (Pluronic® F-127). MATERIALS AND METHODS: NLCi dispersions were prepared based on the melt-emulsification and ultrasonication technique...
May 2017: Pharmaceutical Development and Technology
Fei Li, Zhiguo Xia, Quanlin Liu
The ability to control dopants and defects, as well as the core/shell structures, of quantum dots (QDs) is an essential nanotechnology to modify and optimize their photoluminescence properties. Herein, the optimized ZnS:Mn2+/ZnS/ZnS:Cu2+/ZnS core/multi-shell QDs have been prepared, and their luminescence properties depending on the ratios of the starting materials and the injection temperature of extra sulfur source were discussed, and finally the white light can be possibly obtained by mixing the blue light (emission peak at 450 nm originating from Cu2+ dopants; or emission peaks at 405 nm and 430 nm corresponding to defect emission center...
February 27, 2017: ACS Applied Materials & Interfaces
Michael P Thomas, Yeo Jung Park, Scott Grey, Theodore L Schreiber, Hitinder S Gurm, Dale Leffler, Thomas P Davis, Peter Henke, Paul Michael Grossman
OBJECTIVES: The aim is to examine trends in procedural indication, arterial beds treated, and device usage in peripheral arterial interventions (PVIs). BACKGROUND: There is little data on indication, vascular beds treated and devices utilized for peripheral arterial interventions. METHODS: We used data from 43 hospitals participating in the BMC2 VIC registry. PVIs were separated by year and divided by arterial segment. Lower extremity PVIs were subclassified as having been performed for claudication or critical limb ischemia (CLI)...
February 27, 2017: Catheterization and Cardiovascular Interventions
Matthias Schulz, Majvor Mack, Oliver Kolloge, Arne Lützen, Manuela Schiek
We suggest and explore a novel route towards organic photodetectors sensitive to the circular polarization state of light. For this, we insert fullerene-blended thin films of homochiral squaraine compounds acting as a highly circular dichroic active layer into conventional bulk hetero-junction photodiodes. Initially, we discuss steady-state characterization of photodiodes with unpolarized light. The homochiral, l-proline derived squaraine compounds are obtained via a chiral pool synthesis in sizable quantities...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Soumalya Mukherjee, Edamana Prasad, Anju Chadha
Bathochromic and hypsochromic shifts in the photo-luminescent spectra of doped and functionalized carbon nano-dots (CDs) arise due to the complex interaction between CDs and the solvent molecules around them. Nitrogen-functionalized carbon nano-dots (N-CDs) were synthesized from citric acid and urea using microwave assisted hydrothermal methods. Optical studies (absorption and photoluminescence) from the as-synthesized N-CDs were carried out in polar protic, aprotic and non-polar solvents. When excited at 355 nm, blue photoluminescence (PL) was observed from the N-CDs dispersed in polar aprotic solvents while green emission was observed in polar protic solvents...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Moges Tsega, F B Dejene
Titanium dioxide (TiO2) nanoparticles were prepared by the sol-gel method at different pH values (3.2-6.8) with a hydrochloric acid (HCl) solution. Raw samples were calcined at 500 °C for 2 h. The effects of pH on the structural, morphological and optical properties of TiO2 nanoparticles were investigated. At pH 4.4-6.8, only the anatase phase of TiO2 was observed. Under strong acidic condition at pH 3.2 rutile, brookite and anatase co-exist, but rutile is the predominant phase. The strain value increased and the crystallite size decreased as the HCl content increased...
February 2017: Heliyon
William A Morris, Tristan Butler, Milena Kolpaczynska, Cassandra L Fraser
Difluoroboron β-diketonate (BF2bdk) compounds exhibit solid-state switchable luminescence under excitation by UV light. This property is usually manifested as a blue-shift in emission when dye films are thermally annealed followed by a red-shift in response to mechanical shear (i.e. mechanochromic luminescence). Here we report thiophene and furan heterocycle-substituted dyes bearing short methoxy and long dodecyloxy chain substituents. Optical properties of the dyes were investigated in solution, pristine powders, and films on paper and glass...
January 1, 2017: Mater Chem Front
Harry B Gray, Jay R Winkler
Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O2-reactive enzymes, raising the possibility that they play an antioxidant protective role...
October 2016: Israel Journal of Chemistry
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