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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Structural and Biochemical Characterization of Two Binding Sites for Nucleation-promoting Factor WASp-VCA on Arp2/3 Complex

Actin-related protein (Arp) 2/3 complex mediates the formation of actin filament branches during endocytosis and at the leading edge of motile cells. The pathway of branch formation is ambiguous owing to uncertainty regarding the stoichiometry and location of VCA binding sites on Arp2/3 complex. Isothermal titration calorimetry showed that the CA motif from the C terminus of fission yeast WASP (Wsp1p) bound to fission yeast and bovine Arp2/3 complex with a stoichiometry of 2 to 1 and very different affinities for the two sites (K{sub d}s of 0.13 and 1.6 {micro}M for fission yeast Arp2/3 complex). Equilibrium binding, kinetic, and cross-linking experiments showed that (i) CA at high-affinity site 1 inhibited Arp2/3 complex binding to actin filaments, (ii) low-affinity site 2 had a higher affinity for CA when Arp2/3 complex was bound to actin filaments, and (iii) Arp2/3 complex had a much higher affinity for free CA than VCA cross-linked to an actin monomer. Crystal structures showed the C terminus of CA bound to the low-affinity site 2 on Arp3 of bovine Arp2/3 complex. The C helix is likely to bind to the barbed end groove of Arp3 in a position for VCA to deliver the first actin subunit to the daughter filament.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Circuit complexity and functionality: A statistical thermodynamics perspective

Circuit complexity, defined as the minimum circuit size required for implementing a particular Boolean computation, is a foundational concept in computer science. Determining circuit complexity is believed to be a hard computational problem. Recently, in the context of black holes, circuit complexity has been promoted to a physical property, wherein the growth of complexity is reflected in the time evolution of the Einstein-Rosen bridge (“wormhole”) connecting the two sides of an anti-de Sitter “eternal” black hole. Here, we are motivated by an independent set of considerations and explore links between complexity and thermodynamics for functionally equivalent circuits, making the physics-inspired approach relevant to real computational problems, for which functionality is the key element of interest. In particular, our thermodynamic framework provides an alternative perspective on the obfuscation of programs of arbitrary length—an important problem in cryptography—as thermalization through recursive mixing of neighboring sections of a circuit, which can be viewed as the mixing of two containers with “gases of gates.” This recursive process equilibrates the average complexity and leads to the saturation of the circuit entropy, while preserving functionality of the overall circuit. The thermodynamic arguments hinge on ergodicity in the space of circuits which we conjecture is limited to disconnected ergodic sectors due to fragmentation. The notion of fragmentation has important implications for the problem of circuit obfuscation as it implies that there are circuits of same size and functionality that cannot be connected via a polynomial number of local moves. Furthermore, we argue that fragmentation is unavoidable unless the complexity classes NP and coNP coincide, a statement that implies the collapse of the polynomial hierarchy of computational complexity theory to its first level.

Science & Technology - Other Topics↗
DOE OSTI2016

SU-F-P-64: The Impact of Plan Complexity Parameters On the Plan Quality and Deliverability of Volumetric Modulated Arc Therapy with Canonical Correlation Analysis

Purpose: To evaluate the impact of complexity indices on the plan quality and deliverability of volumetric modulated arc therapy (VMAT), and to determine the most significant parameters in the generation of an ideal VMAT plan. Methods: A multi-dimensional exploratory statistical method, canonical correlation analysis (CCA) was adopted to study the correlations between VMAT parameters of complexity, quality and deliverability, as well as their contribution weights with 32 two-arc VMAT nasopharyngeal cancer (NPC) patients and 31 one-arc VMAT prostate cancer patients. Results: The MU per arc (MU/Arc) and MU per control point (MU/CP) of NPC were 337.8±25.2 and 3.7±0.3, respectively, which were significantly lower than those of prostate cancer patients (MU/Arc : 506.9±95.4, MU/CP : 5.6±1.1). The plan complexity indices indicated that two-arc VMAT plans were more complex than one-arc VMAT plans. Plan quality comparison confirmed that one-arc VMAT plans had a high quality than two-arc VMAT plans. CCA results implied that plan complexity parameters were highly correlated with plan quality with the first two canonical correlations of 0.96, 0.88 (both p<0.001) and significantly correlated with deliverability with the first canonical correlation of 0.79 (p<0.001), plan quality and deliverability was also correlated with the first canonical correlation of 0.71 (p=0.02). Complexity parameters of MU/CP, segment area (SA) per CP, percent of MU/CP less 3 and planning target volume (PTV) were weighted heavily in correlation with plan quality and deliveability . Similar results obtained from individual NPC and prostate CCA analysis. Conclusion: Relationship between complexity, quality, and deliverability parameters were investigated with CCA. MU, SA related parameters and PTV volume were found to have strong effect on the plan quality and deliverability. The presented correlation among different quantified parameters could be used to improve the plan quality and the efficiency of the radiotherapy process when creating a complex VMAT plan.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

The Rnf Complex of Clostridium ljungdahlii Is a Proton-Translocating Ferredoxin:NAD(+) Oxidoreductase Essential for Autotrophic Growth

It has been predicted that the Rnf complex of Clostridium ljungdahlii is a proton-translocating ferredoxin: NAD(+) oxidoreductase which contributes to ATP synthesis by an H+-translocating ATPase under both autotrophic and heterotrophic growth conditions. The recent development of methods for genetic manipulation of C. ljungdahlii made it possible to evaluate the possible role of the Rnf complex in energy conservation. Disruption of the C. ljungdahlii rnf operon inhibited autotrophic growth. ATP synthesis, proton gradient, membrane potential, and proton motive force collapsed in the Rnf-deficient mutant with H-2 as the electron source and CO2 as the electron acceptor. Heterotrophic growth was hindered in the absence of a functional Rnf complex, as ATP synthesis, proton gradient, and proton motive force were significantly reduced with fructose as the electron donor. Growth of the Rnf-deficient mutant was also inhibited when no source of fixed nitrogen was provided. These results demonstrate that the Rnf complex of C. ljungdahlii is responsible for translocation of protons across the membrane to elicit energy conservation during acetogenesis and is a multifunctional device also implicated in nitrogen fixation. IMPORTANCE Mechanisms for energy conservation in the acetogen Clostridium ljungdahlii are of interest because of its potential value as a chassis for the production of biocommodities with novel electron donors such as carbon monoxide, syngas, and electrons derived from electrodes. Characterizing the components implicated in the chemiosmotic ATP synthesis during acetogenesis by C. ljungdahlii is a prerequisite for the development of highly productive strains. The Rnf complex has been considered the prime candidate to be the pump responsible for the formation of an ion gradient coupled with ATP synthesis in multiple acetogens. However, experimental evidence for a proton-pumping Rnf complex has been lacking. This study establishes the C. ljungdahlii Rnf complex as a proton-translocating ferredoxin: NAD(+) oxidoreductase and demonstrates that C. ljungdahlii has the potential of becoming a model organism to study proton translocation, electron transport, and other functions of the Rnf complex in energy conservation or other processes.

Tremblay, PL↗
DOE OSTI2014

Modeling Damage Complexity-Dependent Non-Homologous End-Joining Repair Pathway

Non-homologous end joining (NHEJ) is the dominant DNA double strand break (DSB) repair pathway and involves several repair proteins such as Ku, DNA-PKcs, and XRCC4. It has been experimentally shown that the choice of NHEJ proteins is determined by the complexity of DSB. In this paper, we built a mathematical model, based on published data, to study how NHEJ depends on the damage complexity. Under an appropriate set of parameters obtained by minimization technique, we can simulate the kinetics of foci track formation in fluorescently tagged mammalian cells, Ku80-EGFP and DNA-PKcs-YFP for simple and complex DSB repair, respectively, in good agreement with the published experimental data, supporting the notion that simple DSB undergo fast repair in a Ku-dependent, DNA-PKcs-independent manner, while complex DSB repair requires additional DNA-PKcs for end processing, resulting in its slow repair, additionally resulting in slower release rate of Ku and the joining rate of complex DNA ends. Based on the numerous experimental descriptions, we investigated several models to describe the kinetics for complex DSB repair. An important prediction of our model is that the rejoining of complex DSBs is through a process of synapsis formation, similar to a second order reaction between ends, rather than first order break filling/joining. The synapsis formation (SF) model allows for diffusion of ends before the synapsis formation, which is precluded in the first order model by the rapid coupling of ends. Therefore, the SF model also predicts the higher number of chromosomal aberrations observed with high linear energy transfer (LET) radiation due to the higher proportion of complex DSBs compared to low LET radiation, and an increased probability of misrejoin following diffusion before the synapsis is formed, while the first order model does not provide a mechanism for the increased effectiveness in chromosomal aberrations observed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Bimetallic Coinage Metal Complexes of Tetradentate ortho Ter arylene Ligands

The synthesis, structural and photophysical properties of five bimetallic coinage metal complexes of three tetradentate charge-transfer (CT) ligands are presented. The ligand structures incorporate donor/acceptor moieties electronically decoupled by ortho connection to a bridging biphenylene group. The M M distances observed in the crystal structures of the bimetallic complexes are shorter than the sum of the Van der Waals radii of the metal ions, suggesting stabilizing interactions between the d10 metal centers. Additionally, short distances between the bridging biphenylene and metal atoms suggest arylene metal interactions. Bimetallic Cu, Ag, and Au complexes of the ligand incorporating a carbazole donor and pyridyl acceptor (N2R22-) show absorption and emission energies that trend with the ionization potential of each metal, indicating metal character in the excited state. These properties contrast with our previously reported mononuclear Zn complex of N2R22-The structural and photophysical properties of five bimetallic d10 coinage metal complexes were presented. The M M distances observed in the crystal structures of the bimetallic complexes are shorter than the sum of the metals’ Van der Waals radii, suggesting attractive interactions between the d10 metal centers. Additionally, short distances between the bridging biphenylene and metal atoms suggest arylene metal interactions. The absorption and emission spectra of the bimetallic complexes redshift based on the oxidation potential of the metal ion. This suggests involvement of metal based orbitals in the excited state transitions of the bimetallic complexes, which was corroborated by molecular modeling. High photoluminescent quantum yields were observed in solution and in rigid media (up to PL = 0.75), and the excited state lifetimes in solution were found to exceed several microseconds.

Shariaty, Darius Allen [University of Southern Cal↗
DOE OSTI2011

A Series of Supramolecular Complexes for Solar Energy Conversion via Water Reduction to Produce Hydrogen: An Excited State Kinetic Analysis of Ru(II),Rh(III),Ru(II) Photoinitiated Electron Collectors

Mixed-metal supramolecular complexes have been designed that photochemically absorb solar light, undergo photoinitiated electron collection and reduce water to produce hydrogen fuel using low energy visible light. This manuscript describes these systems with an analysis of the photophysics of a series of six supramolecular complexes, [{(TL)2Ru(dpp)}2RhX2](PF6)5 with TL = bpy, phen or Ph2phen with X = Cl or Br. The process of light conversion to a fuel requires a system to perform a number of complicated steps including the absorption of light, the generation of charge separation on a molecular level, the reduction by one and then two electrons and the interaction with the water substrate to produce hydrogen. The manuscript explores the rate of intramolecular electron transfer, rate of quenching of the supramolecules by the DMA electron donor, rate of reduction of the complex by DMA from the 3 MLCT excited state, as well as overall rate of reduction of the complex via visible light excitation. Probing a series of complexes in detail exploring the variation of rates of important reactions as a function of sub-unit modification provides insight into the role of each process in the overall efficiency of water reduction to produce hydrogen. The kinetic analysis shows that the complexes display different rates of excited state reactions that vary with TL and halide. The role of the MLCT excited state is elucidated by this kinetic study which shows that the 3 MLCT state and not the 3 MMCT is likely that key contributor to the photoreduction of these complexes. The kinetic analysis of the excited state dynamics and reactions of the complexes are important as this class of supramolecules behaves as photoinitiated electron collectors and photocatalysts for the reduction of water to hydrogen.

supramolecular photocatalysis↗
DOE OSTI2012

Glutathione Complex Formation With Mercury(Ii) in Aqueous Solution at Physiological Ph

The mercury(II) complexes formed in neutral aqueous solution with glutathione (GSH, here denoted AH{sub 3} in its triprotonated form) were studied using Hg L{sub III}-edge extended X-ray absorption fine structure (EXAFS) and {sup 199}Hg NMR spectroscopy, complemented with electrospray ionization mass spectrometric (ESI-MS) analyses. The [Hg(AH){sub 2}]{sup 2-} complex, with the Hg-S bond distances at 2.325 {+-} 0.01 {angstrom} in linear S-Hg-S coordination, and the {sup 199}Hg NMR chemical shift at -984 ppm, dominates except at high excess of glutathione. In a series of solutions with C{sub Hg(II)} {approx} 17 mM and GSH/Hg(II) mole ratios rising from 2.4 to 11.8, the gradually increasing mean Hg-S bond distance corresponds to an increasing amount of the [Hg(AH){sub 3}]{sup 4-} complex. ESI-MS peaks appear at -m/z values of 1208 and 1230 corresponding to the [Na{sub 4}Hg(AH){sub 2}(A)]{sup -} and [Na{sub 5}Hg(AH)(A){sub 2}]{sup -} species, respectively. In another series of solutions at pH 7.0 with CHg(II) 50 mM and GSH/Hg(II) ratios from 2.0 to 10.0, the Hg L{sub III}-edge EXAFS and {sup 199}Hg NMR spectra show that at high excess of glutathione (0.35 M) about 70% of the total mercury(II) concentration is present as the [Hg(AH){sub 3}]4- complex, with the average Hg-S bond distance 2.42 {+-} 0.02 {angstrom} in trigonal HgS{sub 3} coordination. The proportions of HgSn species, n = 2, 3, and 4, quantified by fitting linear combinations of model EXAFS oscillations to the experimental EXAFS data in our present and previous studies were used to obtain stability constants for the [Hg(AH){sub 3}]{sup 4-} complex and also for the [Hg(A){sub 4}]{sup 10-} complex that is present at high pH. For Hg(II) in low concentration at physiological conditions (pH 7.4, C{sub GSH} = 2.2 mM), the relative amounts of the HgS{sub 2} species [Hg(AH){sub 2}]{sup 2-}, [Hg(AH)(A)]{sup 3-}, and the HgS{sub 3} complex [Hg(AH){sub 3}]{sup 4-} were calculated to be 95:2:3. Our results are not consistent with the formation of dimeric Hg(II)-GSH complexes proposed in a recent EXAFS study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Complex matrix multiplication operations with data pre-conditioning in a high performance computing architecture

Mechanisms for performing a complex matrix multiplication operation are provided. A vector load operation is performed to load a first vector operand of the complex matrix multiplication operation to a first target vector register. The first vector operand comprises a real and imaginary part of a first complex vector value. A complex load and splat operation is performed to load a second complex vector value of a second vector operand and replicate the second complex vector value within a second target vector register. The second complex vector value has a real and imaginary part. A cross multiply add operation is performed on elements of the first target vector register and elements of the second target vector register to generate a partial product of the complex matrix multiplication operation. The partial product is accumulated with other partial products and a resulting accumulated partial product is stored in a result vector register.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Binary Complex Neural Network Acceleration on FPGA

Being able to learn from complex data with phase information is imperative for many signal processing applications. Today’s real-valued deep neural networks (DNNs) have shown efficiency in latent information analysis but fall short when applied to the complex domain. Deep complex networks (DCN) , in contrast, can learn from complex data, but have high computational costs; therefore, they cannot satisfy the instant decision making requirements of many deployable systems dealing with short observations or short signal bursts. Recent, Binarized Complex Neural Network (BCNN), which integrates DCNs with binarized neural networks (BNN), shows great potential in classifying complex data in real-time. In this paper, we propose a structural pruning based accelerator of BCNN, which is able to provide more than 5000 frames/s inference throughput on edge devices. The high performance comes from both the algorithm and hardware sides. On the algorithm side, we conduct structural pruning to the original BCNN models and obtain 20 × pruning rates with negligible accuracy loss; on the hardware side, we propose a novel 2D convolution operation accelerator for the binary complex neural network. Experimental results show that the proposed design works with over 90% utilization and is able to achieve the inference throughput of 5882 frames/s and 4938 frames/s for complex NIN-Net and ResNet-18 using CIFAR-10 dataset and Alveo U280 Board.

Peng, Hongwu↗
DOE OSTI2013

Alternative Endpoints and Approaches for the Remediation of Contaminated Groundwater at Complex Sites - 13426

The goal of United States (U.S.) Department of Energy's (DOE)'s environmental remediation programs is to restore groundwater to beneficial use, similar to many other Federal and state environmental cleanup programs. Based on past experience, groundwater remediation to pre-contamination conditions (i.e., drinking water standards or non-detectable concentrations) can be successfully achieved at many sites. At a subset of the most complex sites, however, complete restoration is not likely achievable within the next 50 to 100 years using today's technology. This presentation describes several approaches used at complex sites in the face of these technical challenges. Many complex sites adopted a long-term management approach, whereby contamination was contained within a specified area using active or passive remediation techniques. Consistent with the requirements of their respective environmental cleanup programs, several complex sites selected land use restrictions and used risk management approaches to accordingly adopt alternative cleanup goals (alternative endpoints). Several sites used long-term management designations and approaches in conjunction with the alternative endpoints. Examples include various state designations for groundwater management zones, technical impracticability (TI) waivers or greater risk waivers at Superfund sites, and the use of Monitored Natural Attenuation (MNA) or other passive long-term management approaches over long time frames. This presentation will focus on findings, statistics, and case studies from a recently-completed report for the Department of Defense's Environmental Security Technology Certification Program (ESTCP) (Project ER-0832) on alternative endpoints and approaches for groundwater remediation at complex sites under a variety of Federal and state cleanup programs. The primary objective of the project was to provide environmental managers and regulators with tools, metrics, and information needed to evaluate alternative endpoints for groundwater remediation at complex sites. A statistical analysis of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites receiving TI waivers will be presented as well as case studies of other types of alternative endpoints and alternative remedial strategies that illustrate the variety of approaches used at complex sites and the technical analyses used to predict and document cost, time frame, and potential remedial effectiveness. This presentation is intended to inform DOE program managers, state regulators, practitioners and other stakeholders who are evaluating technical cleanup challenges within their own programs, and establishing programmatic approaches to evaluating and implementing long-term management approaches. Case studies provide examples of long-term management designations and strategies to manage and remediate groundwater at complex sites. At least 13 states consider some designation for groundwater containment in their corrective action policies, such as groundwater management zones, containment zones, and groundwater classification exemption areas. Long-term management designations are not a way to 'do nothing' or walk away from a site. Instead, soil and groundwater within the zone is managed to be protective of human health and the environment. Understanding when and how to adopt a long-term management approach can lead to cost savings and the more efficient use of resources across DOE and at numerous other industrial and military sites across the U.S. This presentation provides context for assessing the use and appropriate role of alternative endpoints and supporting long-term management designations in final remedies. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Chemical Complexity Controls Energy Dissipation and Defect Evolution

The development of metallic alloys is arguably one of the oldest sciences, dating back at least 3,000 years. Most research and applications have been focused on alloys with comprised multiple phases with one or two dominant elements, to which the addition of alloying elements in low concentrations leads to various performance improvements and changes in radiation resistance. In sharp contrast to traditional alloys, recent success in the synthesis of single phase concentrated solid solution alloys (SP-CSAs) has opened up new frontiers in materials research. In these alloys, a random arrangement of multiple elemental species on a lattice (fcc or bcc) results in unique site-to-site lattice distortions and local disordered chemical environments. Intense radiation in nuclear fission and fusion energy power systems, nuclear waste forms, high-energy accelerators and space exploration transfers energy to the electrons and atoms that make up the material, and thereby produces defects that ultimately compromise material strength and lifetime. A grand challenge in materials research is to understand complex electronic correlations and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Since SP-CSAs possess unique links between intrinsic material properties (can be altered by alloy complexity), energy dissipation and various defect dynamic processes; they are ideal systems to fill knowledge gaps between electronic- /atomic-level interactions and radiation resistance mechanisms. In our work, we show that chemical disorder and compositional complexity in SP-CSAs have an enormous impact on defect dynamics through substantial modification of energy dissipation pathways. Based on a closely integrated computational and experimental study using a novel set of Ni-based SP-CSAs, we have explicitly demonstrated that increasing chemical disorder can lead to a substantial reduction in the electron mean free path and electrical and thermal conductivity. These reductions have a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Considerable enhancement in radiation resistance with increasing chemical complexity from pure nickel to binary, and to more complex quaternary solid solutions, is observed under ion irradiation. Contrary to conventional alloys with low solute concentration but multiple phases, energy dissipation and defect evolution at the level of electrons and atoms in SP- CSA systems with extreme compositional disorder is an unexplored frontier in materials science. The integrated experimental/modeling effort provides new insights into defect dynamics at the level of atoms and electrons, and an innovative path forward towards solving a long-standing challenge in structural materials. Increasing chemical complexity achieved orders-of-magnitude reductions in electron mean free paths and electron and thermal conductivities of alloys of NiCo, NiFe and NiCoFeCr, compared to Ni, and suppressed damage accumulation under ion irradiation. This discovery provides insights to address the grand challenge of understanding complex electronic correlations and non-equilibrium atomic interactions, and the effect of these intrinsic properties and dynamic processes on energy transfer and defect evolution in irradiated materials. Understanding how material properties and defect dynamics can be tailored by alloy complexity may pave the way for new design principles of functional alloys. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2011

Complexation Studies of Bidentate Heterocyclic N-Donor Ligands with Nd(III) and Am(III)

A new bidentate nitrogen donor complexing agent that combines pyridine and triazole functional groups, 2-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyridine (PTMP), has been synthesized. The strength of its complexes with trivalent americium (Am3+) and neodymium (Nd3+) in anhydrous methanol has been evaluated using spectrophotometric techniques. The purpose of this investigation is to assess this ligand (as representative of a class of similarly structured species) as a possible model compound for the challenging separation of trivalent actinides from lanthanides. This separation, important in the development of advanced nuclear fuel cycles, is best achieved through the agency of multidentate chelating agents containing some number of nitrogen or sulfur donor groups. To evaluate the relative strength of the bidentate complexes, the derived constants are compared to those of the same metal ions with 2,2*-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2-pyridin-2-yl-1H-benzimidazole (PBIm). At issue is the relative affinity of the triazole moiety for trivalent f element ions. For all ligands, the derived stability constants are higher for Am3+ than Nd3+. In the case of Am3+ complexes with phen and PBIm, the presence of 1:2 (AmL2) species is indicated. Possible separations are suggested based on the relative stability and stoichiometry of the Am3+ and Nd3+ complexes. It can be noted that the 1,2,3-triazolyl group imparts a potentially useful selectivity for trivalent actinides (An(III)) over trivalent lanthanides (Ln(III)), though the attainment of higher complex stoichiometries in actinide compared with lanthanide complexes may be an important driver for developing successful separations.

10 SYNTHETIC FUELS↗
DOE OSTI2015

One-dimensional Co(II)/Ni(II) complexes of 2-hydroxyisophthalate: Structures and magnetic properties

The solvothermal reactions of 2-hydroxyisophthalic acid (H{sub 3}ipO) with M(NO{sub 3}){sub 2}∙6H{sub 2}O (M=Co, Ni) afforded two complexes [Co{sub 2}(HipO){sub 2}(Py){sub 2}(H{sub 2}O){sub 2}] (1) and [Ni(HipO)(Py)H{sub 2}O] (2) (Py=pyridine). They exhibit similar zig-zag chain structures with the adjacent two metal centers connected by a anti-syn bridging carboxylate group from the HipO{sup 2−} ligand. The magnetic measurements reveal the dominant antiferromagnetic interactions and spin-canting in 1 while ferromagnetic interactions in 2. Both of them exhibit magnetocaloric effect (MCE) with the resulting entropy changes (−ΔS{sub m}) of 12.51 J kg{sup −1} K{sup −1} when ΔH=50 kOe at 3 K for 1 and 11.01 J kg{sup −1} K{sup −1} when ΔH=50 kOe at 3 K for 2, representing the rare examples of one-dimensional complexes with MCE. - Graphical abstract: Synopsis: Two Co(II)/Ni(II) complexes with zig-zag chain structures have been reported. 1-Co shows cant-antiferromagnetism while 2-Ni shows ferromagnetism. Magnetocaloric effect is also found in both of them. - Highlights: • Two one-dimensional Co(II)/Ni(II) complexes were solvothermally synthesized. • The Co-complex exhibits canted antiferromagnetism. • The Ni-complex exhibits ferromagnetism. • Both of the complexes display magnetocaloric effect.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Synthesis and Characterization of Uranium Complexes Supported by Substituted Aryldimethylsilylanilide Ligands

Here, we report the synthesis and characterization of substituted aryldimethylsilyldiisopropylanilide ligands and their respective bisamido complexes of U(III), (3,5-R 2 -PhMe 2 SiNDipp) 2 UI(dioxane) x (1, R = H, x= 0; 2, R = Me, x = 0; 3, R = t Bu, x = 1). We found that the steric bulk of the 3,5-R 2 -Ph ring affects the hapticity of the U–arene interaction. In the solid-state, 1 is a U–(η 6 -arene) complex, while 2 is a bis(U–(η 1 -arene)) complex. Theoretically calculated bond orders at PBE0 and PBE0-D3 levels of theory support these hapticity assignments. The 3,5- t Bu 2 -Ph rings of 3 are too bulky to interact with U and solid-state metrical parameters initially suggested a U–(η 1 -arene) interaction with one of the Dipp rings. However, bond order calculations show that this interaction is even weaker than in the previously reported ((PhMe 2 Si) 2 N) 3 U complex, leading to the conclusion that 3 is best described as a U–(η o -arene) complex. Molecular orbital analyses in conjunction with electron localization methods reveal that the U–(η 6 -arene) bonding in 1 is primarily electrostatic in nature. Some charge transfer takes place from the arene π orbitals to the U 6d/5f hybrid orbitals in addition to subtle δ-back-bonding. In 2 and 3, both π and δ interactions are substantially weaker, in agreement with the differences in the U–arene coordination modes. Surprisingly, attempts to generate less sterically bulky (3,5-R 2 -PhMe 2 SiNPh) 2 UI complexes results in disproportionation to homoleptic tetraamido (3,5-R 2 -PhMe 2 SiNPh) 4 U(IV) (4, R = H; 5, R = Me) complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

A QUALITATIVE METHOD TO ESTIMATE HSI DISPLAY COMPLEXITY

There is mounting evidence that complex computer system displays in control rooms contribute to cognitive complexity and, thus, to the probability of human error. Research shows that reaction time increases and response accuracy decreases as the number of elements in the display screen increase. However, in terms of supporting the control room operator, approaches focusing on addressing display complexity solely in terms of information density and its location and patterning, will fall short of delivering a properly designed interface. This paper argues that information complexity and semantic complexity are mandatory components when considering display complexity and that the addition of these concepts assists in understanding and resolving differences between designers and the preferences and performance of operators. This paper concludes that a number of simplified methods, when combined, can be used to estimate the impact that a particular display may have on the operator's ability to perform a function accurately and effectively. We present a mixed qualitative and quantitative approach and a method for complexity estimation.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2021

Preparation, characterization, and structural studies of new ruthenium(II) and ruthenium(III) complexes incorporating pyrazole ligands

Multimetallic complexes containing disparate metals have been established to have practical utilities. We previously reported a strategy for preparing such species by using combinations of neutral pyrazole (Hpyz, C 3 N 2 H 4 ) and anionic pyrazolyl ligands (pyz, C 3 N 2 H 3 – ), and herein are reported several new complexes that should be capable of incorporating a second metal center. Two of the complexes, [Ru(1,5-cod)(Hpyz) 3 Cl][BPh 4 ] and Ru(1,5-cod)(Hpyz) 2 (pyz) 2 (cod = cyclooctadiene), were prepared from [Ru(cod)Cl 2 ] 2 , while [Ru(tmeda)(Hpyz) 2 Cl 2 ][BF 4 ] (tmeda = tetramethylethylenediamine) was prepared from the neutral Ru(II) complex Ru(tmeda)(Hpyz) 2 Cl 2 via one electron oxidation by the ferricinium ion. The first two complexes, one cationic and the other uncharged, involve Ru(II), while the tmeda complex involves Ru(III). Finally, all three species have been structurally characterized.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Synthesis, Photoluminescence Behavior of Green Light Emitting Tb(III) Complexes and Mechanistic Investigation of Energy Transfer Process

A series of five new terbium(III) ion complexes with 4,4-difluoro-1-phenylbutane-1,3-dione (HDPBD) and anciliary ligands was synthesized. The composition and properties of complexes were analyzed by elemental analysis, IR, NMR, powder X-ray diffaraction, TG-DTG and photoluminescence spectroscopy. These complexes exhibited ligand sensitized green emission at 546 nm associated with {sup 5}D{sub 4} → {sup 7}F{sub 5} transitions of terbium ion in the emission spectra. The photoluminescence study manifested that the organic ligands act as antenna and facilitate the absorbed energy to emitting levels of Tb(III) ion efficiently. The enhanced luminescence intensity and decay time of ternary C2-C5 complexes observed due to synergistic effect of anciliary ligands. The CIE color coordinates of complexes came under the green region of chromaticity diagram. The mechanistic investigation of intramolecular energy transfer in the complexes was discussed in detail. These terbium(III) complexes can be thrivingly used as one of the green component in light emitting material and in display devices. .

74 ATOMIC AND MOLECULAR PHYSICS↗