Synthesis of Dendridic NLO Chromophores for the Improvement of Order in Electro-optics

2004 ◽  
Vol 846 ◽  
Author(s):  
Jessica Sinness ◽  
Olivier Clot ◽  
Scott R. Hammond ◽  
Nishant Bhatambrekar ◽  
Harrison L. Rommel ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Electrostatic Interactions ◽  
Dipole Moments ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Quantum Calculations ◽  
Electro Optic ◽  
The Matrix ◽  
Macroscopic Domain ◽  
Nlo Chromophores

ABSTRACTPrevious research in organic electro-optics has shown dramatic increases in the hyperpolarizablity of NLO chromophores. However, this large microscopic activity has not been translated to the macroscopic domain. The polymeric electro-optic (E-O) materials continue to lack the high noncentrosymmetric order of the poled chromophores within the matrix necessary for high E-O response (r33). This deficiency of order represents one major obstacle that must be overcome before E-O device commercialization can be achieved. This lack of order is partially due to the large dipole moments of high μβ chromophores, which cause the chromophores to align in a centrosymmetric fashion through intermolecular electrostatic interactions. However, quantum calculations show that when the aspect ratio between the width and length of the chromophore system is adjusted to be greater than 1.4:1 by adding bulky side groups around the center of the chromophore, it would prevent side on pairing of the chromophores. This would cause a decrease in the large areas of centrosymmetric aggregation and thus allow for easier poling of the system. Here we report the synthesis of a nanoscale NLO architecture in which dendritic moieties have been incorporated around the center of the chromophore to give a three dimensional structure in order to achieve the 1.4:1 aspect ratio and maximize the macroscopic order of the system.

Understanding Bacterial Ice Nucleation

2021 ◽  
Author(s):  
Ralph Schwidetzky ◽  
Max Lukas ◽  
Anna T. Kunert ◽  
Ulrich Pöschl ◽  
Janine Fröhlich-Nowoisky ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Affinity Purification ◽  
Hydration Shell ◽  
Three Dimensional ◽  
American Chemical Society ◽  
Chemical Society ◽  
Ice Nucleation ◽  
Dimensional Structure ◽  
Protein Activity ◽  
Ice Nucleators

<p>Bacterial ice-nucleating proteins (INPs) promote heterogeneous ice nucleation better than any known material. On the molecular scale, bacterial INPs are believed to function by organizing water into ice‑like patterns to enable the formation of embryonic crystals. However, the details of their working mechanism remains largely elusive. Here, we report the results of comprehensive evaluations of environmentally relevant effects such as changes in pH, the presence of ions and temperature on the activity, three-dimensional structure and hydration shell of bacterial ice nucleators using ice affinity purification, high-throughput ice nucleation assays and surface-specific sum-frequency generation spectroscopy.</p><p> </p><p>[1] Lukas, Max, et al. "Electrostatic Interactions Control the Functionality of Bacterial Ice Nucleators." Journal of the American Chemical Society 142.15 (2020): 6842-6846.</p><p>[2] Lukas, Max, et al. "Interfacial Water Ordering Is Insufficient to Explain Ice-Nucleating Protein Activity." The Journal of Physical Chemistry Letters 12 (2020): 218-223.</p>

Assembly states of the nucleosome assembly protein 1 (NAP-1) revealed by sedimentation velocity and non-denaturing MS

2011 ◽  
Vol 436 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Masanori Noda ◽  
Susumu Uchiyama ◽  
Adam R. McKay ◽  
Akihiro Morimoto ◽  
Shigeki Misawa ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Electrostatic Interactions ◽  
Analytical Ultracentrifugation ◽  
Three Dimensional ◽  
Sedimentation Velocity ◽  
Dimensional Structure ◽  
Histone H2a ◽  
Nucleosome Assembly ◽  
Nucleosome Assembly Protein ◽  
Nucleosome Assembly Protein 1

Proteins often exist as ensembles of interconverting states in solution which are often difficult to quantify. In the present manuscript we show that the combination of MS under nondenaturing conditions and AUC-SV (analytical ultracentrifugation sedimentation velocity) unambiguously clarifies a distribution of states and hydrodynamic shapes of assembled oligomers for the NAP-1 (nucleosome assembly protein 1). MS established the number of associated units, which was utilized as input for the numerical analysis of AUC-SV profiles. The AUC-SV analysis revealed that less than 1% of NAP-1 monomer exists at the micromolar concentration range and that the basic assembly unit consists of dimers of yeast or human NAP-1. These dimers interact non-covalently to form even-numbered higher-assembly states, such as tetramers, hexamers, octamers and decamers. MS and AUC-SV consistently showed that the formation of the higher oligomers was suppressed with increasing ionic strength, implicating electrostatic interactions in the formation of higher oligomers. The hydrodynamic shapes of the NAP-1 tetramer estimated from AUC-SV agreed with the previously proposed assembly models built using the known three-dimensional structure of yeast NAP-1. Those of the hexamer and octamer could be represented by new models shown in the present study. Additionally, MS was used to measure the stoichiometry of the interaction between the human NAP-1 dimer and the histone H2A–H2B dimer or H3–H4 tetramer. The present study illustrates a rigorous procedure for the analysis of protein assembly and protein–protein interactions in solution.

Aromatic interactions in proteins, DNA and synthetic receptors

1993 ◽  
Vol 345 (1674) ◽  
pp. 77-85 ◽  
Keyword(s):  
Electrostatic Interactions ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dimensional Structure ◽  
Π Interactions ◽  
Aromatic Stacking ◽  
Dna Base ◽  
Conformational Preferences ◽  
Out Of Plane ◽  
Dna Base Pair

Non-covalent interactions between aromatic molecules (π-π interactions) play a major role in biological molecular recognition. A simple theoretical model which accounts for the geometric properties of π-π interactions is described. The key feature of this model is that it specifically allows for out-of-plane π-electron density in the calculation of electrostatic interactions. Experimental evidence for the validity of the model comes from studies of the geometric distribution of phenylalanine-phenylalanine interactions in protein X-ray crystal structures. The model has also been used to design a synthetic molecular receptor which recognizes p -benzoquinone using H-bonds and edge-to-face π-π interactions. Aromatic stacking interactions provide the crucial link between sequence and three-dimensional structure in double-helical DNA. The π-π interaction model has been used to calculate the conformational preferences of all ten DNA base-pair steps and the results provide new insight into the molecular basis of sequence-dependent DNA structure.

scholarly journals Progress of shrink polymer micro- and nanomanufacturing

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wenzheng He ◽  
Xiongying Ye ◽  
Tianhong Cui
Keyword(s):  
Aspect Ratio ◽  
Antenna Arrays ◽  
High Aspect Ratio ◽  
Electrochemical Sensors ◽  
Wearable Sensors ◽  
Three Dimensional ◽  
Fabrication Process ◽  
Dimensional Structure ◽  
Optical Antenna ◽  
Cell Alignment

AbstractTraditional lithography plays a significant role in the fabrication of micro- and nanostructures. Nevertheless, the fabrication process still suffers from the limitations of manufacturing devices with a high aspect ratio or three-dimensional structure. Recent findings have revealed that shrink polymers attain a certain potential in micro- and nanostructure manufacturing. This technique, denoted as heat-induced shrink lithography, exhibits inherent merits, including an improved fabrication resolution by shrinking, controllable shrinkage behavior, and surface wrinkles, and an efficient fabrication process. These merits unfold new avenues, compensating for the shortcomings of traditional technologies. Manufacturing using shrink polymers is investigated in regard to its mechanism and applications. This review classifies typical applications of shrink polymers in micro- and nanostructures into the size-contraction feature and surface wrinkles. Additionally, corresponding shrinkage mechanisms and models for shrinkage, and wrinkle parameter control are examined. Regarding the size-contraction feature, this paper summarizes the progress on high-aspect-ratio devices, microchannels, self-folding structures, optical antenna arrays, and nanowires. Regarding surface wrinkles, this paper evaluates the development of wearable sensors, electrochemical sensors, energy-conversion technology, cell-alignment structures, and antibacterial surfaces. Finally, the limitations and prospects of shrink lithography are analyzed.

scholarly journals The wake structure and thrust performance of a rigid low-aspect-ratio pitching panel

2008 ◽  
Vol 603 ◽  
pp. 331-365 ◽  
Author(s):  
JAMES H. J. BUCHHOLZ ◽  
ALEXANDER J. SMITS
Keyword(s):  
Aspect Ratio ◽  
Strouhal Number ◽  
Three Dimensional ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Dimensional Structure ◽  
Peak Efficiency ◽  
Thrust Coefficient ◽  
Wake Structure ◽  
Thrust Performance

Thrust performance and wake structure were investigated for a rigid rectangular panel pitching about its leading edge in a free stream. For ReC = O(104), thrust coefficient was found to depend primarily on Strouhal number St and the aspect ratio of the panel AR. Propulsive efficiency was sensitive to aspect ratio only for AR less than 0.83; however, the magnitude of the peak efficiency of a given panel with variation in Strouhal number varied inversely with the amplitude to span ratio A/S, while the Strouhal number of optimum efficiency increased with increasing A/S. Peak efficiencies between 9% and 21% were measured. Wake structures corresponding to a subset of the thrust measurements were investigated using dye visualization and digital particle image velocimetry. In general, the wakes divided into two oblique jets; however, when operating at or near peak efficiency, the near wake in many cases represented a Kármán vortex street with the signs of the vortices reversed. The three-dimensional structure of the wakes was investigated in detail for AR = 0.54, A/S = 0.31 and ReC = 640. Three distinct wake structures were observed with variation in Strouhal number. For approximately 0.20 < St < 0.25, the main constituent of the wake was a horseshoe vortex shed by the tips and trailing edge of the panel. Streamwise variation in the circulation of the streamwise horseshoe legs was consistent with a spanwise shear layer bridging them. For St > 0.25, a reorganization of some of the spanwise vorticity yielded a bifurcating wake formed by trains of vortex rings connected to the tips of the horseshoes. For St > 0.5, an additional structure formed from a perturbation of the streamwise leg which caused a spanwise expansion. The wake model paradigm established here is robust with variation in Reynolds number and is consistent with structures observed for a wide variety of unsteady flows. Movies are available with the online version of the paper.

Sign in / Sign up

Export Citation Format

Share Document