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Alexander T Martin, Melissa Tan, Shane M Nichols, Emily Timothy, Bart Kahr
Accurate polarimetric measurements of the optical activity of crystals along low symmetry directions are facilitated by isotropic points, frequencies where dispersion curves of eigenrays cross and the linear birefringence disappears. We report here the optical properties and structure of achiral, uniaxial (point group D2d ) potassium trihydrogen di-(cis-4-cyclohexene-1,2-dicarboxylate) dihydrate, whose isotropic point was previously detected (S. A. Kim, C. Grieswatch, H. Küppers, Zeit. Krist. 1993; 208:219-222) and exploited for a singular measurement of optical activity normal to the optic axis...
May 7, 2018: Chirality
Karim Rafie, Andrii Gorelik, Riccardo Trapannone, Vladimir S Borodkin, Daan M F Aalten
O-GlcNAc transferase (OGT) is an essential glycosyltransferase that installs the O-GlcNAc posttranslational modification on the nucleocytoplasmic proteome. We report the development of S-linked UDP-peptide conjugates as potent bisubstrate OGT inhibitors. These compounds were assembled in a modular fashion by photo-initiated thiol-ene conjugation of allyl-UDP and optimal acceptor peptides in which the acceptor serine was replaced with cysteine. The conjugate VTPVC(S-propyl-UDP)TA (Ki = 1.3 µM) inhibits the OGT activity in HeLa cell lysates...
May 3, 2018: Bioconjugate Chemistry
S Stamnes, C Hostetler, R Ferrare, S Burton, X Liu, J Hair, Y Hu, A Wasilewski, W Martin, B van Diedenhoven, J Chowdhary, I Cetinić, L K Berg, K Stamnes, B Cairns
We present an optimal-estimation-based retrieval framework, the microphysical aerosol properties from polarimetry (MAPP) algorithm, designed for simultaneous retrieval of aerosol microphysical properties and ocean color bio-optical parameters using multi-angular total and polarized radiances. Polarimetric measurements from the airborne NASA Research Scanning Polarimeter (RSP) were inverted by MAPP to produce atmosphere and ocean products. The RSP MAPP results are compared with co-incident lidar measurements made by the NASA High-Spectral-Resolution Lidar HSRL-1 and HSRL-2 instruments...
April 1, 2018: Applied Optics
Prabhu K Venuthurumilli, Peide D Ye, Xianfan Xu
Black phosphorus, a recently intensely investigated two dimensional material, is promising for electronic and optoelectronic applications due to its higher mobility and thickness dependent direct band gap. With its low direct band gap and anisotropic properties in nature, black phosphorus is also suitable for near infrared polarization sensitive photodetection. To enhance photoresponsivity of black phosphorus based photodetector, we demonstrate two designs of plasmonic structures. In the first design, plasmonic bowtie antennas are used to increase the photocurrent, particularly in the armchair direction where the optical absorption is higher than that in the zigzag direction...
April 23, 2018: ACS Nano
Arul Prakash Francis, Sneha Gurudevan, A Jayakrishnan
Polymannose (PM) having a weight-average molar mass (Mw ) of 30-53 kDa was synthesized by the polycondensation of mannose using phosphorous acid as the catalyst and characterized by various techniques such as NMR, IR, GPC and polarimetry. 2D NMR results confirmed the presence of (1→ 6)-linked α-D-mannose residues as backbone with O-3 and O-2 substituted linear or branched chains in PM. Amphotericin B (AmB) was conjugated to periodate-oxidized PM through Schiff's linkages at 20 wt% concentration. The AmB-PM conjugates were highly soluble in phosphate buffered saline (180-250 mg/mL), exhibited negligible hemolytic potential to human erythrocytes even at a concentration of 200 μg /mL (equivalent to ~ 40 μg/mL AmB) and were non-toxic to human embryonic kidney (HEK293T) cells even at a concentration of 250 μg/mL (equivalent to ~ 50 μg/mL AmB)...
April 23, 2018: Journal of Biomaterials Science. Polymer Edition
Igor Aleksandrovich Zobkalo, Sergei Gavrilov, Andrew Sazonov, Vladimir Hutanu
In order to make a new approach to the elucidation of the microscopic mechanisms of multiferroicity in RMn2O5 family, experiments with different methods of polarized neutrons scattering were performed on a TbMn2O5 single crystal. We employed three different techniques of polarized neutron diffraction: without the analysis after scattering, the XYZ-polarization analysis, and technique of spherical neutron polarimetry (SNP). Measurements with SNP were undertaken both with and without external electric field. A characteristic difference in the population of "right" and "left" helix domains in all magnetically ordered phases of TbMn2O5, was observed...
April 13, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ching-Min Chang, Yu-Lung Lo, Nghia-Khanh Tran, Yu-Jen Chang
A method is proposed for characterizing the optical properties of articular cartilage sliced from a pig's thighbone using a Stokes-Mueller polarimetry technique. The principal axis angle, phase retardance, optical rotation angle, circular diattenuation, diattenuation axis angle, linear diattenuation, and depolarization index properties of the cartilage sample are all decoupled in the proposed analytical model. Consequently, the accuracy and robustness of the extracted results are improved. The glucose concentration, collagen distribution, and scattering properties of samples from various depths of the articular cartilage are systematically explored via an inspection of the related parameters...
March 20, 2018: Applied Optics
Alexander B Tibbs, Ilse M Daly, Nicholas W Roberts, David R Bull
In addition to the visual information contained in intensity and color, imaging polarimetry allows visual information to be extracted from the polarization of light. However, a major challenge of imaging polarimetry is image degradation due to noise. This paper investigates the mitigation of noise through denoising algorithms and compares existing denoising algorithms with a new method, based on BM3D (Block Matching 3D). This algorithm, Polarization-BM3D (PBM3D), gives visual quality superior to the state of the art across all images and noise standard deviations tested...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Poonam Malik, Ravi Bhushan
Enantioselective analysis of (RS)-fexofenadine has been carried out by achiral HPLC via derivatization approach using N-hydroxy-benzotriazolyl-(S)-naproxen ester (synthesised for this purpose) and three chirally pure amines as chiral derivatizing reagents (CDRs). There occurred formation of amide and anhydride types of diastereomeric derivatives. These were separated and isolated by HPLC (analytical and preparative). The structures and configurations were verified via recording full scan product ion mass spectra using LC-MS,1 HNMR spectra, Chem3D Pro 12...
March 30, 2018: Biomedical Chromatography: BMC
Eliot F Fenton, Adnan Khan, Pablo Solano, Luis A Orozco, Fredrik K Fatemi
Light that carries linear or angular momentum can interact with a mechanical object, giving rise to optomechanical effects. In particular, a photon can transfer its intrinsic angular momentum to an object when the object either absorbs the photon or changes the photon polarization, as in an action/reaction force pair. Here, we demonstrate resonant driving of torsional mechanical modes of a single-mode tapered optical nanofiber using spin angular momentum. The nanofiber torsional mode spectrum is characterized by polarimetry, showing narrow natural resonances (Q≈2,000)...
April 1, 2018: Optics Letters
Joshua A Jones, Rebecca A Metzler, Anthony J D'Addario, Carrie Burgess, Brian Regan, Samantha Spano, Ben A Cvarch, Enrique J Galvez
Nacre is a complex biomaterial made of aragonite-tablet bricks and organic mortar that is considerably resilient against breakage. Nacre has been studied with a wide range of laboratory techniques, leading to understanding key fundamentals, and informing the creation of bio-inspired materials. In this article we present an optical polarimetric technique to investigate nacre, taking advantage of the translucence and birefringence of its micro-components. We focus our study on three classes of mollusks that have nacreous shells: bivalve (Pinctada fucata), gastropod (Haliotis asisina and Haliotis rufescens) and cephalopod (Nautilus pompilius)...
March 25, 2018: Journal of Biophotonics
L-P Regnault, C Boullier, J E Lorenzo
The magnetic properties of the cobaltite BaCo2 (AsO4 )2 , a good realization of the quasi two-dimensional frustrated honeycomb-lattice system with strong planar anisotropy, have been reinvestigated by means of spherical neutron polarimetry with CRYOPAD. From accurate measurements of polarization matrices both on elastic and inelastic contributions as a function of the scattering vector Q , we have been able to determine the low-temperature magnetic structure of BaCo2 (AsO4 )2 and reveal its puzzling in-plane spin dynamics...
January 2018: Heliyon
Jaepyeong Cha, Aline Broch, Scott Mudge, Kihoon Kim, Jung-Man Namgoong, Eugene Oh, Peter Kim
Accurate, real-time identification and display of critical anatomic structures, such as the nerve and vasculature structures, are critical for reducing complications and improving surgical outcomes. Human vision is frequently limited in clearly distinguishing and contrasting these structures. We present a novel imaging system, which enables noninvasive visualization of critical anatomic structures during surgical dissection. Peripheral nerves are visualized by a snapshot polarimetry that calculates the anisotropic optical properties...
March 1, 2018: Biomedical Optics Express
Isabel de la Cueva-Alique, Sara Sierra, Laura Muñoz-Moreno, Adrián Pérez-Redondo, Ana M Bajo, Isabel Marzo, Lourdes Gude, Tomás Cuenca, Eva Royo
New water soluble, enantiopure arene ruthenium compound SRu SN -(1R,4S)-[(η6 -p-cymene)Ru{ĸNH(Bn),ĸNOH}Cl]Cl (Bn = benzyl, 1a') has been synthesized. The novel compound along with that previously described RRu RN -(1S,4R)-[(η6 -p-cymene)Ru{ĸNH(Bn),ĸNOH}Cl]Cl (1a) was evaluated by polarimetry, ultra-violet and circular dichroism spectroscopy. The structure of novel ruthenium derivative 1a' was determined by single crystal X-ray crystallography. Both enantiomers have been tested against several cancer cell lines in vitro: prostate PC-3, lung A-549, pancreas MIA PaCa-2, colorectal HCT-116, leukemia Jurkat and cervical HeLa...
June 2018: Journal of Inorganic Biochemistry
C H Lucas Patty, David A Luo, Frans Snik, Freek Ariese, Wybren Jan Buma, Inge Loes Ten Kate, Rob J M van Spanning, William B Sparks, Thomas A Germer, Győző Garab, Michael W Kudenov
Spectropolarimetry of intact plant leaves allows to probe the molecular architecture of vegetation photosynthesis in a non-invasive and non-destructive way and, as such, can offer a wealth of physiological information. In addition to the molecular signals due to the photosynthetic machinery, the cell structure and its arrangement within a leaf can create and modify polarization signals. Using Mueller matrix polarimetry with rotating retarder modulation, we have visualized spatial variations in polarization in transmission around the chlorophyll a absorbance band from 650 nm to 710 nm...
March 9, 2018: Biochimica et Biophysica Acta
T R Gentile, P J Nacher, B Saam, T G Walker
This article reviews the physics and technology of producing large quantities of highly spin-polarized 3 He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3 He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena...
October 2017: Reviews of Modern Physics
Tran Trung Luu, Hans Jakob Wörner
Berry phase and Berry curvature have become ubiquitous concepts in physics, relevant to a variety of phenomena, such as polarization, various Hall effects, etc. Studies of these phenomena call for characterization of Berry phase or curvature which is largely limited to theory, and a few measurements in optical lattices. In this work, we report polarimetry of high-harmonic emission from solids and exploit this novel capability to directly retrieve the Berry curvature of α-quartz. We show that the two manifestations of broken inversion symmetry in solids lead to perpendicular or parallel polarization of even harmonics with respect to the driving field...
March 2, 2018: Nature Communications
Yong Liu, Xuezhen Zhou, C Benjamin Naman, Yanbin Lu, Lijian Ding, Shan He
The contamination of foods and animal feeds with trichothecene mycotoxins is a growing concern for human and animal health. As such, large quantities of pure trichothecene mycotoxins are necessary for food safety monitoring and toxicological research. A new and effective method for the purification of trichothecene mycotoxins from a marine fungus, Fusarium sp. LS68, is described herein. Preparative high-speed countercurrent chromatography (HSCCC) was utilized for the scalable isolation and purification of four trichothecene mycotoxins for the first time in stepwise elution mode, with a biphasic solvent system composed of hexanes-EtOAc-CH₃OH-H₂O (6:4:5:5, v / v / v / v ) and (8...
February 24, 2018: Marine Drugs
W Y Gong, S Q Liu, Y M Dong, X J Gao, X F Chen
OBJECTIVE: To compare the osteogenic effects of a nano-sized 58S bioactive glass (nano-58S BG) and a traditional 45S5 bioactive glass(45S5 BG) in penetrating parietal critical bone defects. METHODS: Critical bone defect with 9 mm diameter was created in the parietal bone of New Zealand rabbits. The bone defects were then filled with either nano-58S BG, or 45S5 BG, or nothing but the newly-formed blood clot as the blank control at random. For histological observation, specimens were gained 4 and 8 weeks after the surgery, sectioned and stained by HE...
February 18, 2018: Beijing da Xue Xue Bao. Yi Xue Ban, Journal of Peking University. Health Sciences
Pengcheng Li, Donghong Lv, Honghui He, Hui Ma
Polarization imaging and Mueller polarimetry provide powerful tools for probing the microstructure of complex anisotropic media, which is a core task in material science, biomedical diagnosis and many research fields. However, Mueller matrix elements and many polarization parameters are sensitive to the spatial orientation of the sample and experimental configurations, hindering the effectiveness for distinguishing different sources of anisotropies. In this paper, we propose a set of rotation invariant parameters and corresponding orientation parameters, which are explicit functions of the Mueller matrix elements...
February 19, 2018: Optics Express
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