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The influence of molecular orientation on organic bulk heterojunction solar cells Print
Monday, 28 April 2014 09:03

Work done on ALS Beamlines 11.0.1.2, 7.3.3, and 5.3.2.2. reveals that preferential orientation of polymer chains with respect to the fullerene domain leads to a high photovoltaic performance. Featured on the cover of Nature Photonics 8. Article link

 
Crystal nucleation and near-epitaxial growth in nacre Print
Thursday, 12 December 2013 13:56

Nacre--the iridescent inner lining of many mollusk shells-- has a unique strcuture that is remarkably resistant to fracture. The nacre featured on this cover is from Haliotis laevigata with average layer thickness 470-nm. The colors represent crystal orientationthe crystal lattice tilts across tablets.left stack all tablets are yellow, hence all aragonite crystals are co-oriented. The central stack shows a color gradient from red to black, thus,. In this PIC-map color represents crystal orientation Read more.

 
Ring Cycle for Dilating and Constricting the Nuclear Pore Print
Thursday, 13 June 2013 09:30

Pictured is an illustration of several nuclear pore complexes (NPCs) embedded in a cell nucleus. NPCs act as gatekeepers between a cell’s cytoplasm and its nucleus. Based on crystallographic analyses, Sozanne R. Solmaz et al. uncover the molecular mechanism that underlies the large changes in diameter of NPCs and suggest a “ring cycle” mechanism for dilating and constricting the central NPC channel. The model could explain the ability of NPCs to accommodate transport substrates of a large size range and rapidly adjust to cellular transport needs. Read the full article. (Image courtesy of Sozanne R. Solmaz, Günter Blobel, and Ivo Melčák.)

 
Jamming Behavior of Domains in a Spiral Antiferromagnetic System Print
Tuesday, 04 June 2013 13:34

Using resonant magnetic x-ray photon correlation spectroscopy, this research shows that the domains of a spiral antiferromagnet enter a jammed state at the onset of long-range order. This schematic of x-ray scattering is from a spiral antiferromagnet with a spin structure that gives rise to domains with jamming behavior.

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Solar Cells: Spin-Cast Bulk Heterojunction Solar Cells: A Dynamical Investigation Print
Wednesday, 03 April 2013 13:32

Spin-coating is extensively used in the lab-based manufacturing of organic solar cells, including most of the record-setting cells. Aram Amassian and co-workers report in this study the first direct observation of photoactive layer formation as it occurs during spin-coating. The study provides new insight into mechanisms and kinetics of bulk heterojunction formation, which may be crucial for successful transfer to printing processes and scaling up production.

 
Real-Time Quantitative Imaging of Failure Events in Materials Under Load at Temperatures Above 1,600 °C Print
Monday, 25 March 2013 00:00

Gathering information on the evolution of small cracks in ceramic matrix composites used in hostile environments such as in gas turbines and hypersonic flights has been a challenge. It is now shown that sequences of microcrack damage in ceramic composites under load at temperatures up to 1,750 °C can be fully resolved with the use of in situ synchrotron x-ray computed microtomography. Article (PDF). News and Views (PDF).

 
Organic Solar Cells: Absolute Measurement of Domain Composition and Nanoscale Size Distribution Explains Performance in Solar Cells Print
Tuesday, 22 January 2013 00:00

This front cover represents the morphology and resulting device dynamics in organic solar cell blend films of PTB7 and PC71BM, as revealed by combined resonant x-ray scattering and microscopy done at the Advanced Light Source. Harald Ade and co-workers find that the fullerene molecules (red) are miscible in the polymer (blue) up to 30 wt.%, above which they begin to agglomerate (bottom). This agglomeration is important for the optoelectronic processes within the device, but the agglomerates must be kept to small sizes by the solvent processing additive diiodooctane (DIO). Correlation of this morphology with the spectrally resolved quantum efficiency shows that the yellow excitons created upon photoabsorption must arrive at the agglomerate interface for charge separation to occur. The blue electrons and green holes can then percolate through appropriate molecules in the mixed matrix to the electrodes for harvesting of electrical energy. Article Link (PDF)

 
Sequestering Uranium from Seawater: Binding Strength and Modes of Uranyl Complexes with Glutarimidedioxime Print
Sunday, 14 October 2012 00:00

The ocean is an important source of uranium if it can be extracted economically. Extraction of uranium from seawater is very challenging, not only because it is in an extremely low concentration, but also because it exists in seawater as very stable carbonate complexes in the presence of many other metal ions (Na, K, Ca, Mg, Al and transition metals), some of which are in overwhelmingly higher concentrations. Since the 1960s, various techniques have been studied and developed for the extraction of uranium from seawater. Among these, the Japanese process using amidoxime-based sorbents prepared by radiation grafting showed the most promise. A better understanding of the coordination modes and binding strength of the amidoxime group with uranium is the key to improving the extraction efficiency and selectivity. Article Link .

 
Molecular conformations, interactions, and properties associated with drug efficiency and clinical performance among VEGFR TK inhibitors Print
Monday, 17 September 2012 00:00

Pictured are crystals that contain VEGFR2 tyrosine kinase in complex with an inhibitor from a class of potent anticancer drugs. Michele McTigue et al. produced these and similar crystals to determine the structural basis for the significant variation in potency and clinical performance of members of this anticancer drug class. The authors found that conformations of an often-neglected kinase domain affect the efficiency with which inhibitors bind. Understanding the relationship between kinase conformation and inhibitor efficiency could help optimize drug design for in vivo performance. Article Link (PDF)

Image courtesy of Robert S. Kania.

 
Plant UVR8 Photoreceptor Senses UV-B by Tryptophan-Mediated Disruption of Cross-Dimer Salt Bridges Print
Friday, 23 March 2012 09:55

science-photoreceptor In plants, the UVR8 protein senses ultraviolet-B (UV-B) wavelengths in sunlight, triggering changes in growth and development, including the production of a protective chemical sunscreen. Pyramids of tryptophan rings intrinsic to UVR8 create a built-in light switch; no separate chromophore is required. Article link.

 
Metal Ion-Assisted Transformations of 2-Pyridinealdoxime and Hexafluorophosphate Print
Monday, 05 March 2012 15:26

Metal-ion mediated reactions of 2-pyridinealdoxime and hexafluorophosphate lead to ZnII complexes containing picolinic acid, picolinamide and monofluorophosphate (−2) as ligands. Article Link (PDF)

Read more about this publication in the ALS Science Brief Metal-Ion-Mediated Reactions.

 
Mollusk Shell Nacre Ultrastructure Correlates with Environmental Temperature and Pressure Print
Tuesday, 07 February 2012 00:00

Nacre, or mother-of-pearl, is the tough, iridescent biomineral lining the inner side of some mollusk shells. The micro-structure of nacre is correlated with the temperature at which nacre was deposited. It is therefore possible that mollusk shell nacre could be used as a thermometer for modern and past climates. Once validated nacre could become a physical, non-chemical temperature proxy. The shells shown here are representative of the three nacre-forming mollusk classes: gastropods, bivalves, and cephalopods, respectively (Haliotis rufescens, Pinctada margaritifera, Nautilus pompilius). Article Link (PDF)

 
Autophagy Ubiquitin-Like Protein Transfer In Trans Print
Friday, 04 November 2011 00:00

The cover depicts how the autophagy ubiquitin-like protein Atg8 is transferred from its E1, Atg7, to its E2, Atg3 (Taherbhoy et al., pp. 451–461). The two halves of the yin-yang represent the homodimeric Atg7. The circles within the yin-yang represent the Atg7 catalytic cysteines to which the ubiquitin-like protein Atg8 is transiently covalently linked. Each Atg7 monomer is capable of recruiting Atg3. Structural, biophysical, and biochemical data indicate that Atg3 binds to one Atg7 protomer and reaches across to accept Atg8 from the opposite protomer of Atg7 within the dimer. Article Link (PDF)

Read more about this publication in the ALS Science Brief Understanding the Autophagy Pathway.

 
XRCC4 Protein Interactions with XRCC4-like Factor (XLF) Create an Extended Grooved Scaffold for DNA Ligation and Double Strand Break Repair Print
Wednesday, 20 July 2011 00:00

The cover shows a protein plasticity and filament formation of XRCC4 (gold) in complex with ligase IV tandem BRCT domains (red) and with XLF (XRCC4-like factor, green). The article by Hammel et al., pages 32638–32650, describes the combination of crystallography, small angle x-ray scattering, and hydrogen-deuterium exchange mass spectrometry in the characterization of the XRCC4-XLF-DNA complex that permits multiple protein interactions leading to double strand break repair. Article Link (PDF)

 
Building of a Novel Mn12 Single Molecule Magnet by Assembly of Anisotropic Triangles Print
Wednesday, 06 July 2011 12:58

Assembly of triangular {MnIII3(O)(salox)3}+ fragments mediated by azido ligands, results in the dodecanuclear [Mn12O4(salox)12(N3)4(MeOH)4(H2O)2] complex with S = 8 ground state and SMM response. After the discovery of the Single-Molecule-Magnet (SMM) behaviour of [Mn6(O)2(salox)6(R-COO)2] (salox = salicylaldoxime, R = Me, Ph) complexes in 2004,1 the chemistry of this family of [Mn6] clusters has been studied in depth: the systematic change of the carboxylato ligands, the study of substitutedR-saloxH2 related ligands,2 the effect of variation of the oxidation state,3 the response under pressure4 or the one-dimensional assembly of [Mn6] units into chains of clusters5 with Single-Chain-Magnet behaviour in some cases,5c,d turn this system into one of the best known in the SMM field. One of the main goals of this work, developed by Brechin et al. has been to modulate the value of the ground spin level, reaching the maximum possible spin S = 12 by means of the adequate choice of methyl or ethyl substituted salicylaldoximes and the understanding of the structural features that control the coupling inside the triangles. Article Link (PDF)

 
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