Imaging reveals a fifth heart chamber: Diagnosing and treating a massive left atrial appendage aneurysm.

In this case report, a 33-year-old male with a history of smoking presented with recurrent palpitations and chest discomfort. Holter monitoring revealed atrial flutter, and imaging showed a giant left atrial appendage aneurysm. Due to the risk of arrhythmias and thromboembolic events, surgical resection was performed successfully.

Elucidating interprotein energy transfer dynamics within the antenna network from purple bacteria.

In photosynthesis, absorbed light energy transfers through a network of antenna proteins with near-unity quantum efficiency to reach the reaction center, which initiates the downstream biochemical reactions. While the energy transfer dynamics within individual antenna proteins have been extensively studied over the past decades, the dynamics between the proteins are poorly understood due to the heterogeneous organization of the network. Previously reported timescales averaged over such heterogeneity, obscuring individual interprotein energy transfer steps.

Ultrafast energy transfer between lipid-linked chromophores and plant light-harvesting complex II.

Light-Harvesting Complex II (LHCII) is a membrane protein found in plant chloroplasts that has the crucial role of absorbing solar energy and subsequently performing excitation energy transfer to the reaction centre subunits of Photosystem II. LHCII provides strong absorption of blue and red light, however, it has minimal absorption in the green spectral region where solar irradiance is maximal. In a recent proof-of-principle study, we enhanced the absorption in this spectral range by developing a biohybrid system where LHCII proteins together with lipid-linked Texas Red (TR) chromophores were assembled into lipid membrane vesicles.

Comparison of the Energy-Transfer Rates in Structural and Spectral Variants of the B800-850 Complex from Purple Bacteria.

Photosynthetic light harvesting can occur with a remarkable near-unity quantum efficiency. The B800-850 complex, also known as light-harvesting complex 2 (LH2), is the primary light-harvesting complex in purple bacteria and has been extensively studied as a model system. The bacteriochlorophylls of the B800-850 complex are organized into two concentric rings, known as the B800 and B850 rings.

Substituent effects on H formation via H roaming mechanisms from organic molecules under strong-field photodissociation.

Roaming chemical reactions are often associated with neutral molecules. The recent findings of roaming processes in ionic species, in particular, ones that lead to the formation of H under strong-field laser excitation, are of considerable interest. Given that such gas-phase reactions are initiated by double ionization and subsequently facilitated through deprotonation, we investigate the strong-field photodissociation of ethanethiol, also known as ethyl mercaptan, and compare it to results from ethanol.

Mimicking Microbial Rhodopsin Isomerization in a Single Crystal.

Bacteriorhodopsin represents the simplest, and possibly most abundant, phototropic system requiring only a retinal-bound transmembrane protein to convert photons of light to an energy-generating proton gradient. The creation and interrogation of a microbial rhodopsin mimic, based on an orthogonal protein system, would illuminate the design elements required to generate new photoactive proteins with novel function. We describe a microbial rhodopsin mimic, created using a small soluble protein as a template, that specifically photoisomerizes all- trans to 13- cis retinal followed by thermal relaxation to the all- trans isomer, mimicking the bacteriorhodopsin photocycle, in a single crystal.

H roaming chemistry and the formation of H from organic molecules in strong laser fields.

Roaming mechanisms, involving the brief generation of a neutral atom or molecule that stays in the vicinity before reacting with the remaining atoms of the precursor, are providing valuable insights into previously unexplained chemical reactions. Here, the mechanistic details and femtosecond time-resolved dynamics of H formation from a series of alcohols with varying primary carbon chain lengths are obtained through a combination of strong-field laser excitation studies and ab initio molecular dynamics calculations. For small alcohols, four distinct pathways involving hydrogen migration and H roaming prior to H formation are uncovered.

Ultrafast Dynamics of a "Super" Photobase.

Molecular reactivity can change dramatically with the absorption of a photon due to the difference of the electronic configurations between the excited and ground states. Here we report on the discovery of a modular system (Schiff base formed from an aldehyde and an amine) that upon photoexcitation yields a more basic imine capable of intermolecular proton transfer from protic solvents. Ultrafast dynamics of the excited state conjugated Schiff base reveals the pathway for proton transfer, culminating in a 14-unit increase in pK to give the excited state pK >20 in ethanol.

Mechanisms and time-resolved dynamics for trihydrogen cation (H) formation from organic molecules in strong laser fields.

Strong-field laser-matter interactions often lead to exotic chemical reactions. Trihydrogen cation formation from organic molecules is one such case that requires multiple bonds to break and form. We present evidence for the existence of two different reaction pathways for H formation from organic molecules irradiated by a strong-field laser.

Time-resolved signatures across the intramolecular response in substituted cyanine dyes.

The optically populated excited state wave packet propagates along multidimensional intramolecular coordinates soon after photoexcitation. This action occurs alongside an intermolecular response from the surrounding solvent. Disentangling the multidimensional convoluted signal enables the possibility to separate and understand the initial intramolecular relaxation pathways over the excited state potential energy surface.

Order of Magnitude Dissociative Ionization Enhancement Observed for Pulses with High Order Dispersion.

While the interaction of atoms in strong fields is well understood, the same cannot be said about molecules. We consider how dissociative ionization of molecules depends on the quality of the femtosecond laser pulses, in particular, the presence of third- and fourth-order dispersion. We find that high-order dispersion (HOD) unexpectedly results in order-of-magnitude enhanced ion yields, along with the factor of 3 greater kinetic energy release compared to transform-limited pulses with equal peak intensities.

Controlling S2 Population in Cyanine Dyes Using Shaped Femtosecond Pulses.

Fast population transfer from higher to lower excited states occurs via internal conversion (IC) and is the basis of Kasha's rule, which states that spontaneous emission takes place from the lowest excited state of the same multiplicity. Photonic control over IC is of interest because it would allow direct influence over intramolecular nonradiative decay processes occurring in condensed phase. Here we tracked the S2 and S1 fluorescence yield for different cyanine dyes in solution as a function of linear chirp.

Investigating the role of human serum albumin protein pocket on the excited state dynamics of indocyanine green using shaped femtosecond laser pulses.

Differences in the excited state dynamics of molecules and photo-activated drugs either in solution or confined inside protein pockets or large biological macromolecules occur within the first few hundred femtoseconds. Shaped femtosecond laser pulses are used to probe the behavior of indocyanine green (ICG), the only Food and Drug Administration (FDA) approved near-infrared dye and photodynamic therapy agent, while free in solution and while confined inside the pocket of the human serum albumin (HSA) protein. Experimental findings indicate that the HSA pocket hinders torsional motion and thus mitigates the triplet state formation in ICG.