High-energy States Research Articles

Plasmon-enhanced fluorescence of gold nanoparticle/graphene quantum dots for detection of Cr3+ ions

Graphene quantum dots (GQDs), fascinating semiconductors with stable photoluminescence (PL), have important potential applications in the fields of biology, medicine, and new semiconductor devices. However, it is still challenging to overcome the weak PL intensity. Here, we report a strategy for selective resonance enhancement of GQD fluorescence using gold nanoparticles (AuNPs) as plasmas. Interestingly, the addition of low concentration AuNP makes AuNP/GQDs exhibit significant fluorescence enhancement of 2.67 times in the visible range. The addition of high concentration AuNP leads to the formation of an excitation peak at 421 nm and selectively enhances certain radiation modes. We concluded that the main reason for the selective enhancement of PL intensity in high concentration AuNP is the transfer of generous hot electrons at high energy states from AuNP to GQD and relaxation to the ground state. The electron resonance of low concentration AuNP transfers to GQD and relaxes to lower energy levels, exhibiting an overall enhancement of PL intensity. We apply it for detection of the heavy metal ion Cr3+, and verify that it has a correlation coefficient of 97.36%. We believe AuNP/GQDs can be considered excellent candidates for heavy metal detection and high fluorescence bio-imaging.

Are High-Temperature Molten Salts Reactive with Excess Electrons? Case of ZnCl2.

New and exciting frontiers for the generation of safe and renewable energy have brought attention to molten inorganic salts of fluorides and chlorides. This is because high-temperature molten salts can act both as coolants and liquid fuel in next-generation nuclear reactors. Whereas research from a few decades ago suggests that salts are mostly unreactive to radiation, recent experiments hint at the fact that electrons generated in such extreme environments can react with the melt and form new species including nanoparticles. Our study probes the fate of an excess electron in molten ZnCl2 using first-principles molecular dynamics calculations. We find that on the time scale accessible to our study, an excess electron can be found in one of three states; the lowest-energy state can be characterized as a covalent Zn2Cl5•2- radical ion, the other two states are a solvated Zn•+ species (ZnCl3•2-) and a more delocalized species that still has some ZnCl3•2- character. Since for each of these, the singly occupied molecular orbital (SOMO) where the excess charge resides has a distinct and well-separated energy, the different species can in principle be characterized by their own electronic spectra. The study also sheds light onto what is commonly understood as the spectrum of a transient radical species which can be from the SOMO onto higher energy states or from the melt to pair with the excess electron leaving a hole in the liquid.

A molecular dynamics study on the mechanical response of thermal-pressure rejuvenated CuxZr100−x metallic glasses

A molecular dynamics study was performed on the mechanical response of thermal-pressure rejuvenated CuxZr100−x metallic glasses. The effect of temperature (50, 300, 600 K) and pressure (0–50 GPa) on the rejuvenation process and the mechanical properties of CuxZr100−x including stress–strain response, shear localization formation and elastic modulus were investigated. The thermal-pressure rejuvenation process involves transitioning the system to a higher potential energy state and a lower atomic volume, demonstrating the significant influence of pressure on rejuvenation. Our findings reveal that increasing pressure at specific temperatures and material compositions results in reduced yield stress and stress drop. They also indicate that with increasing pressure, the system undergoes a transition towards homogeneity, resulting in enhanced ductility compared to its initial amorphous state. Additionally, high temperatures contribute to lower values of Young's, shear, and bulk moduli, as well as decreased yield stress and stress drop. Consequently, the system becomes more homogeneous, promoting rejuvenation. Furthermore, we observed that the final yield strength of the system increases with higher Cu content for all structures at specific pressures and temperatures. The level of rejuvenation is additionally impacted by the amount of Cu, and structures containing varying content of Cu demonstrate varying degrees of rejuvenation. To validate our findings, we utilized Voronoi analysis, which revealed a higher fraction of densely-packed clusters in the samples. Finally, a total of 10 materials properties were calculated and explored using statistical analysis which shows there are different correlations between pressure, temperature and atomic composition with mechanical properties.

Microwave Radiation in the Environment and Its Impact on the State of Living Organisms

In the early 1990s [1], we proposed a new agent of the impact of geocosmos on a set of processes in the lower atmosphere and biosphere - the microwave radiation of the earth's ionosphere, emitted by all its atoms, molecules and their ions when high-energy (Rydberg) states are excited by photo- and secondary electrons mainly during solar flares and geomagnetic storms. This made it possible to solve the main problem of the physics of solar-terrestrial relations, since it opened a previously unknown channel for the constant influence of space weather factors on terrestrial processes and the state of the human body. In addition, we proposed to take into account the existence of such a factor when assessing the safety of manned space flights beyond the Earth's magnetosphere [2,10,12], including during the operation of the Moon. In our approach - supramolecular physics of supramolecular structures of molecules with high affinity for the proton (including water in a living organism), we took into account the pioneering works [14,15], in which the possibility of the formation of "polyatomic Rydberg molecules" in such cases was found. Their existence, including in the biological molecules, was discussed in [18]. Here we used the analogy with molecular protonics considered for the biomedium within the framework of supramolecular chemistry [16]. In our studies of the geocosmic contribution to terrestrial processes, we proposed for the first time to take into account the role of microwave emission from the ionosphere in studying the problem of global warming. Such an emission causes the generation of optically thin upper clouds from water-containing associates, which delays the escape of thermal radiation from the surface atmosphere [4]. This was confirmed when interpreting the data of meteorological observations at an altitude of 2100 meters at the Kislovodsk station of the Leningrad University in 2003 [3].

A three-state mechanism for trifluoroethanol denaturation of an intrinsically disordered protein (IDP).

Relating the amino acid composition and sequence to chain folding and binding preferences of intrinsically disordered proteins (IDPs) has emerged as a huge challenge. While globular proteins have respective 3D structures that are unique to their individual functions, IDPs violate this structure-function paradigm because rather than having a well-defined structure an ensemble of rapidly interconverting disordered structures characterize an IDP. This work measures 2,2,2-trifluoroethanol (TFE)-induced equilibrium transitions of an IDP called AtPP16-1 (Arabidopsis thaliana phloem protein type 16-1) by using fluorescence, circular dichroism, infrared, and NMR methods at pH 4, 298 K. Low TFE reversibly removes the tertiary structure to produce an ensemble of obligate intermediate ($\mathrm{I}$) retaining the native-state ($\mathrm{N}$) secondary structure. The intermediate $\mathrm{I}$ is preceded by a non-obligate tryptophan-specific intermediate ${\mathrm{I}}_{\mathrm{w}}$ whose population is detectable for AtPP16-1 specifically. Accumulation of such non-obligate intermediates is discriminated according to the sequence composition of the protein. In all cases, however, a tertiary structure-unfolded general obligate intermediate $\mathrm{I}$ is indispensable. The $\mathrm{I}$ensemble has higher helical propensity conducive to the acquisition of an exceedingly large level of α-helices by a reversible denaturation transition of $\mathrm{I}$ to the denatured state $\mathrm{D}$ as the TFE level is increased. Strikingly, it is the same $\mathrm{N}\rightleftharpoons \mathrm{I}\rightleftharpoons \mathrm{D}$ scheme typifying the TFE transitions of globular proteins. The high-energy state $\mathrm{I}$ characterized by increased helical propensity is called a universal intermediate encountered in both genera of globular and disordered proteins. Neither $\mathrm{I}$ nor $\mathrm{D}$ strictly show molten globule (MG)-like properties, dismissing the belief that TFE promotes MGs.

Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha's Rule.

Fluorescence exclusively occurs from the lowest excited state of a given multiplicity according to Kasha's rule. However, this rule is not obeyed by a handful of anti-Kasha fluorophores whose underlying mechanism is still understood merely on a phenomenological basis. This lack of understanding prevents the rational design and property-tuning of anti-Kasha fluorophores. Here, we propose a model explaining the photophysical properties of an archetypal anti-Kasha fluorophore, azulene, based on its ground- and excited-state (anti)aromaticity. We derived our model from a detailed analysis of the electronic structure of the ground singlet, first excited triplet, and quintet states and of the first and second excited singlet states using the perturbational molecular orbital theory and quantum-chemical aromaticity indices. Our model reveals that the anti-Kasha properties of azulene and its derivatives result from (i) the contrasting (anti)aromaticity of its first and second singlet excited states (S1 and S2, respectively) and (ii) an easily accessible antiaromaticity relief pathway of the S1 state. This explanation of the fundamental cause of anti-Kasha behavior may pave the way for new classes of anti-Kasha fluorophores and materials with long-lived, high-energy excited states.

Highly mixed high-energy d-orbital states enhance oxygen evolution reactions in spinel catalysts

Design, synthesis, and engineering of electrocatalysts for the oxygen evolution reaction (OER) are essential for attaining desirable electrocatalytic performance towards practical implementation. Emerging spinel-type OER catalysts have not reached the desirable activity and durability, thus demanding critical research to advance the field. To achieve enhanced OER performance for spinel-type OER catalysts, we present an efficient strategy of electronic structure modulation of central metal atoms. Modulation of the electronic properties of the Zn and Co atoms through the counter anionic components (O, S, and Se) regulates the adsorption of oxygen intermediates and thus enhances OER activity, which is systematically demonstrated using Density Functional Theory (DFT) calculation. Although the zinc cobalt selenide catalyst showed the less pronounced trigonal distortion, the mixing of eg orbitals with selenium accounts for the experimentally observed enhancement in OER activity. The result is, in contrast to the benchmark catalyst made of RuO2, ZnCo2Se4@rGO demonstrated lower OER overpotential (η10 = 302 mV) and Tafel slope (58 mV dec−1) as well as greater durability at 10 mA cm−2 for 50 h. The implementation of this strategy in several spinel-type catalysts could improve their electrocatalytic performance.

Mixed, nonclassical behavior in a classic allosteric protein

Allostery is a major driver of biological processes requiring coordination. Thus, it is one of the most fundamental and remarkable phenomena in nature, and there is motivation to understand and manipulate it to a multitude of ends. Today, it is often described in terms of two phenomenological models proposed more than a half-century ago involving only T(tense) or R(relaxed) conformations. Here, methyl-based NMR provides extensive detail on a dynamic T to R switch in the classical dimeric allosteric protein, yeast chorismate mutase (CM), that occurs in the absence of substrate, but only with the activator bound. Switching of individual subunits is uncoupled based on direct observation of mixed TR states in the dimer. This unique finding excludes both classic models and solves the paradox of a coexisting hyperbolic binding curve and highly skewed substrate-free T-R equilibrium. Surprisingly, structures of the activator-bound and effector-free forms of CM appear the same by NMR, providing another example of the need to account for dynamic ensembles. The apo enzyme, which has a sigmoidal activity profile, is shown to switch, not to R, but to a related high-energy state. Thus, the conformational repertoire of CM does not just change as a matter of degree depending on the allosteric input, be it effector and/or substrate. Rather, the allosteric model appears to completely change in different contexts, which is only consistent with modern ensemble-based frameworks.

Facile synthesis of platinum-loaded carbon nanosheets with high specific surface area for efficient CWAO of ammonia nitrogen: A low-cost alternative route for treating ammonia containing wastewater

Deep treatment is an important tool to solve the environmental pollution of ammonia-containing wastewater. Considering the stability and economy of industrial application, we propose a simple and economical synthesis strategy. The procedure is based on the carbonization of citrate at elevated temperatures to synthesize high specific surface area and pore-rich carbon nanoflowers, and carbon nanoflower-loaded Pt catalysts were constructed for the catalytic wet air oxidation (CWAO) of ammonia-containing wastewater. The results showed that the synergistic effect of Pt, edge carbon and carboxyl groups led to the increase of CWAO activity. During the reaction, Pt activated NH3 to put it in a high-energy state, and there was a positive synergistic effect between the oxygen-containing functional groups (carboxyl groups) on the surface of the porous carbon nanoflowers and the edge carbon exposed at the adjacent defect sites, which promoted the activation of O2 and the generation of reactive oxygen species. At 200 °C, the Pt1/PC catalysts showed high activity and hydrothermal stability for CWAO of NH3. The conversion of NH3 was 98.24 % within 4 h, and the selectivity of N2 was 100 %. The total nitrogen (TN) was reduced to below 15 mg‧L−1, which meets the Chinese emission standard for TN in petrochemical industry. Therefore, the novel catalyst proposed in this study effectively solved the problems of complicated catalyst synthesis steps and poor hydrothermal stability in ammonia CWAO studies. The catalyst has potential industrial applications for CWAO of ammonia-containing wastewater.

Photobleaching-induced changes in the optical and photochemical properties of algal organic matter.

Algal organic matter (AOM), a significant source of endogenous dissolved organic matter (DOM) is released in high concentrations during cyanobacterial blooms, along with cyanotoxins. Subsequent photobleaching of AOM is an important phenomenon to investigate. In this study, intracellular organic matter (IOM) and extracellular organic matter (EOM) were extracted from cultured cyanobacteria taken from Taihu Lake in China. The formation of photochemically produced reactive intermediates in different stages of IOM and EOM photobleaching was compared to Suwannee River DOM (SRDOM, reference standard DOM). Results revealed notable differences influenced by the pigment component among IOM, EOM, and SRDOM. The pigment in IOM contributed to a triplet state pool with strong energy-transfer but limited electron-transfer capabilities. Notably, IOM exhibited the highest triplets state quantum yield value in the visible region, suggesting its potential significance in pollutant degradation in deeper water layers. For EOM, one of the pools exhibits photolability and remarkable electron-transfer capability, indicating it as a high-energy triplet state component. Moreover, three cyanotoxins (MC-LR, ACA, and ATX-a) were detected in the extracted AOM, and their photodegradation was monitored during the AOM photobleaching process. This highlights the potential role of AOM as a photosensitizer in the natural self-cleaning mechanisms of water bodies, facilitating the degradation of organic pollutants through photochemical reactions. The findings of this study contribute to understanding the dynamic nature of AOM and its implications in environmental processes.

Experimental investigation of electron-mercury atom collisions: insights into atomic interaction dynamics

This experiment aims to validate the Bohr’s model, which posits the existence of discrete energy levels within Hg and Ne atoms, through the Frank-Hertz experimental methodology. Utilizing two specialized tubes, one containing Neon gas and the other Mercury gas, electrons are accelerated to collide with the gas atoms. As the applied voltage is gradually increased, a distinct min-max pattern emerges on the current-voltage graph, with the equidistant minima and maxima, indicating the quantization of atomic energy levels, a phenomenon predicted by Bohr’s model. The experimentally determined distance between these peaks correlates with the energy required to excite the respective gas atoms to a higher energy state. The measured excitation energies – 16.58±2.36 eV for neon and 4.90±0.12 eV for mercury – align closely with the widely accepted energy levels for these atoms. These findings not only corroborate the quantized nature of atomic properties but also reinforce the validity of Bohr’s atomic model.

(Invited) On-the-Fly Non-Adiabatic Dynamics Simulations of Single-Walled Carbon Nanotubes with Covalent Defects

Single-walled carbon nanotubes (SWCNTs) with covalent surface defects have been explored recently due to their promise for use in single-photon telecommunication emission and in spintronic applications. The dynamical evolution of excitons (the primary electronic excitations) in these systems has only been loosely explored using atomistic modeling due to the size-limitations of these large systems. We present computational modeling of non-radiative relaxation on a variety of SWCNT chiralities with single-defect functionalization schemes. Our modeling uses a trajectory surface hopping algorithm accounting for excitonic effects with a configuration interaction approach. We find a strong chirality and defect-composition dependence on the population relaxation (50 – 500 fs) between the nanotube band-gap excitation and the defect-associated, single-photon-emitting state, giving insight into the dynamic trapping nature of these localized excitonic states. Engineering fast population decay into the quasi-two-level sub-system with weak coupling to higher-energy states increases the effectiveness and controllability of these quantum light emitters.

Theoretical predictions and electronic properties of thiolate-protected gold nanocluster: Au44(SR)32

Thiolate-protected gold nanoclusters have received extensive attention both experimentally and theoretically due to their excellent physical and chemical properties. However, comprehending the geometric structure of thiolate-protected gold nanoclusters remains a challenging task. Predicting the structural configuration of these ligand-protected gold nanoclusters can enhance our understanding of this class of materials. Due to the current lack of knowledge regarding the structure of Au44(SR)32, we employed the grand unified model (GUM) for gold core stacking and the ring model to describe interfacial interactions between gold cores and the protection motifs. Based on these models, we successfully predicted the geometric structure of Au44(SR)32 clusters and demonstrated partial reproducibility between the calculated absorption spectra and experimental results. Furthermore, by analyzing the energy levels and molecular orbitals, we have identified that the absorption spectra of Au44(SR)32 arise from d→d and d→sp transitions, with the low-energy state primarily resulting from Au44-to-core transitions and the high-energy state from Au44-to-ligand transitions. These findings not only enhance our understanding of Au44(SR)32 clusters but also validate the effectiveness and applicability of GUM and ring model in predicting stable structures of thiolate-protected gold nanoclusters.

Structural Stability Analysis of Bridge Structure Using FEA

In the current research, the dynamic analysis of bridge structure is conducted to determine the natural frequency and mode shape. The dynamic analysis is conducted using ANSYS FEA simulation package. The critical regions of high deformation and energy states are determined. The analysis revealed the presence of several dominant vibration modes, each associated with distinct deformation patterns and nodal patterns. These findings shed light on potential vulnerability zones and areas of concern that may be susceptible to resonance and excessive vibrations during bridge operation. Understanding these critical modes is vital for designing appropriate damping and vibration control measures to ensure the bridge's long-term stability and safety.

Substrate topographies modulate the secretory activity of human bone marrow mesenchymal stem cells

BackgroundMesenchymal stem cells (MSCs) secrete a diversity of factors with broad therapeutic potential, yet current culture methods limit potency outcomes. In this study, we used topographical cues on polystyrene films to investigate their impact on the secretory profile and potency of bone marrow-derived MSCs (hBM-MSCs). hBM-MSCs from four donors were cultured on topographic substrates depicting defined roughness, curvature, grooves and various levels of wettability.MethodsThe topographical PS-based array was developed using razor printing, polishing and plasma treatment methods. hBM-MSCs from four donors were purchased from RoosterBio and used in co-culture with peripheral blood mononuclear cells (PBMCs) from Cell Applications Inc. in an immunopotency assay to measure immunosuppressive capacity. Cells were cultured on low serum (2%) for 24–48 h prior to analysis. Image-based analysis was used for cell quantification and morphology assessment. Metabolic activity of BM-hMSCs was measured as the mitochondrial oxygen consumption rate using an extracellular flux analyzer. Conditioned media samples of BM-hMSCs were used to quantify secreted factors, and the data were analyzed using R statistics. Enriched bioprocesses were identify using the Gene Ontology tool enrichGO from the clusterprofiler. One-way and two-way ANOVAs were carried out to identify significant changes between the conditions. Results were deemed statistically significant for combined P < 0.05 for at least three independent experiments.ResultsCell viability was not significantly affected in the topographical substrates, and cell elongation was enhanced at least twofold in microgrooves and surfaces with a low contact angle. Increased cell elongation correlated with a metabolic shift from oxidative phosphorylation to a glycolytic state which is indicative of a high-energy state. Differential protein expression and gene ontology analyses identified bioprocesses enriched across donors associated with immune modulation and tissue regeneration. The growth of peripheral blood mononuclear cells (PBMCs) was suppressed in hBM-MSCs co-cultures, confirming enhanced immunosuppressive potency. YAP/TAZ levels were found to be reduced on these topographies confirming a mechanosensing effect on cells and suggesting a potential role in the immunomodulatory function of hMSCs.ConclusionsThis work demonstrates the potential of topographical cues as a culture strategy to improve the secretory capacity and enrich for an immunomodulatory phenotype in hBM-MSCs.

Resonant vibrations produce quantum bridge over high-energy states in heterogeneous antenna.

Photosynthetic light-harvesting complexes usually contain several pools of molecules with a big difference in transition energies, for example, chlorophylls a and b in plant antennas. Some pathways of the excitation energy transfer may include pigments from the low-energy pool separated by a site occupied by a high-energy molecule. We demonstrate that such pathways may be functional if high-frequency intramolecular vibrations fall in resonance with the energy gap between the neighboring molecules belonging to different pools. In this case, a vibration-assisted mixing of the excited states can produce delocalized vibronic states playing a role of 'quantum bridge' that facilitates a passage over high-energy barrier. We perform calculations of the excitation dynamics in the model three-state system with the parameters emerging from our previous studies of real antennas. Simulation of the dynamics in an explicit electron-vibrational basis demonstrates that the rate of transfer between the two chlorophylls a through the chlorophyll b intermediate is increased by a factor of 1.7-2 in the presence of resonant vibration. A possible influence of energetic disorder and other (non-resonant) vibrations on this effect is discussed.

Can [formula omitted] excitations mediate pairing?

The Cu-3d states in the high-Tc cuprates are often described as a single band of 3dx2−y2 states, with the other four 3d states having about 2 to 3 eV higher energy due to the lower-than-octahedral crystal field at the copper sites. However, excitations to these higher energy states observed with RIXS show indications of strong coupling to doped holes in the 3dx2−y2 band. This relaunches a decades-old question of the possible role of the orbital degrees of freedom that once motivated Bednorz and Müller to search for superconductivity in these systems. Here we explore a direction different from the Jahn–Teller electron–phonon coupling considered by Bednorz and Müller, namely the interaction between holes mediated by dd excitations.

A scheme for achieving strength-ductility trade-off in metallic glasses

The strength-ductility paradox in structural materials remains a long-standing dilemma in advanced materials synthesis. Metallic glasses (MGs) that are structural materials of remarkably high-strengths are not exclusive in structural applications due to their inherently poor plasticity. This study addresses this conundrum by presenting a scheme for achieving excellent strength-ductility synergy in MGs from structural and energetic standpoints. By applying a two-step pathway of mechanical rejuvenation and cyclic stress loadings upon a Zr2Cu as-constructed MG model, deformation behavior was analyzed by molecular dynamics simulations. As higher energy states of the MG characterized by enhanced compressive plasticity was found by mechanical rejuvenation due to internal stress accumulation accompanied with an unusual increase in free volume and atomic energy, cyclic stress loading upon rejuvenation annihilated loosely-packed regions to advance a more stable state with less energy to enhance structural stability with an improvement in elastic strain limit and strength. By theoretical modelling, strength-ductility trade-off was demonstrated by the delay in shear transformation zone activities that orchestrated the generation and intersection of multiple shear bands. As a result, a two-step scheme in which soft regions are aggregated to a concentered mass intensified to higher potential energy followed by dissipating the consolidated mass into randomly dispersed soft regions is the key to achieve the strength-ductility trade-off in MG materials. The outcome of this study will further advance structure-property characterization in amorphous solids.

High-energy photoemission final states beyond the free-electron approximation

Three-dimensional (3D) electronic band structure is fundamental for understanding a vast diversity of physical phenomena in solid-state systems, including topological phases, interlayer interactions in van der Waals materials, dimensionality-driven phase transitions, etc. Interpretation of ARPES data in terms of 3D electron dispersions is commonly based on the free-electron approximation for the photoemission final states. Our soft-X-ray ARPES data on Ag metal reveals, however, that even at high excitation energies the final states can be a way more complex, incorporating several Bloch waves with different out-of-plane momenta. Such multiband final states manifest themselves as a complex structure and added broadening of the spectral peaks from 3D electron states. We analyse the origins of this phenomenon, and trace it to other materials such as Si and GaN. Our findings are essential for accurate determination of the 3D band structure over a wide range of materials and excitation energies in the ARPES experiment.

Abstract P1026: Structural And Biochemical Effects Of Missense MyBP-C Mutations On The Myofilament In Human Hypertrophic Cardiomyopathy

Significance: While the disease mechanisms of truncating MyBP-C variants in HCM have been well defined, the mechanisms by which missense MyBP-C variants cause HCM are largely unknown. Recent studies show that unlike truncating variants that push myosin into an active high energy state due to their overall reduction in MyBP-C, missense MyBP-C properly incorporates into the sarcomere without affecting protein abundance. The consequences of missense MyBP-C on myosin have not been explored and may have implications for the treatment of HCM patients with missense MyBP-C variants. Results: We performed small angle X-ray diffraction (XrD) on human HCM tissue from patients with missense MyBP-C, and healthy control hearts. When healthy tissue was moved from relaxing pCa 8 to activating pCa 5 the I 1,1 /I 1,0 equatorial intensity ratio increased (p&lt;0.001) indicating myosin is moving away from the backbone and adopting an active conformation. However, in missense hearts I 1,1 /I 1,0 is lower than healthy hearts at pCa 8 meaning more myosin is localized to the backbone. This is contrary to other HCM mutations which are proposed to push myosin to an active conformation under relaxing conditions. I 1,1 /I 1,0 does not increase at pCa 5 (p&gt;0.05) indicating that at activating Ca myosin remains in the inactive conformation suggesting the thick filament Ca response is impaired in missense hearts. Ongoing Experiments: We are planning to perform XrD on more samples and Mant-ATP assays to determine if the structural inactivation of myosin in missense tissue also results in myosin remaining in the low energy super relaxed state (SRX). We expect the structural state to correlate with the biochemical state meaning missense hearts will demonstrate an equivalent percentage of SRX myosin compared to control hearts. Conclusions: Our finding that the transition of myosin to a structurally active conformation does not occur in human MyBP-C missense hearts distinguishes these variants from other HCM causing mutations such as truncating MyBP-C and missense MYH7 which have been shown to shift myosin to the active disordered relaxed state. If Mant-ATP assays show myosin is maintaining SRX along with an inactive conformation this suggests MyBP-C missense mutations act through a different mechanism.