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The investigation of electronic excited states in single-molecule junctions not only provides platforms to reveal the photophysical and photochemical processes at the molecular level, but also brings opportunities for the development of single-molecule optoelectronic devices. Understanding the interaction mechanisms between molecules and nanocavities is essential to obtain on-demand properties in devices by artificial design, since molecules in junctions exhibit unique behaviors of excited states benefited from the structures of metallic nanocavities. Here, we review the excitation mechanisms involved in the interplay between molecules and plasmonic nanocavities, and reveal the influence of nanostructures on excited-state properties by demonstrating the differences in excited state decay processes. Furthermore, vibronic transitions of molecules between nanoelectrodes are also discussed, offering a new single-molecule characterization method. Finally, we provide the potential applications and challenges in single-molecule optoelectronic devices and the possible directions in exploring the underlying mechanisms of photophysical and photochemical processes.

In this paper, the publicly available dataset for the Combined Diesel-Electric and Gas (CODLAG) propulsion system was used to obtain symbolic expressions for estimation of fuel flow, ship speed, starboard propeller torque, port propeller torque, and total propeller torque using genetic programming (GP) algorithm. The dataset consists of 11,934 samples that were divided into training and testing portions in an 80:20 ratio. The training portion of the dataset which consisted of 9548 samples was used to train the GP algorithm to obtain symbolic expressions for estimation of fuel flow, ship speed, starboard propeller, port propeller, and total propeller torque, respectively. After the symbolic expressions were obtained the testing portion of the dataset which consisted of 2386 samples was used to measure estimation performance in terms of coefficient of correlation (R2) and Mean Absolute Error (MAE) metric, respectively. Based on the estimation performance in each case three best symbolic expressions were selected with and without decay state coefficients. From the conducted investigation, the highest R2 and lowest MAE values were achieved with symbolic expressions for the estimation of fuel flow, ship speed, starboard propeller torque, port propeller torque, and total propeller torque without decay state coefficients while symbolic expressions with decay state coefficients have slightly lower estimation performance.

We estimate the decay rate of the Ψ(2S) to J/Ψ(1S) + 2 π and J/Ψ(1S) + σ + 2 π. This is based on the mixed hybrid theory that was developed for the Ψ(2S) and was used to estimate the ratio Ψ(2S)→J/Ψ(1S)+σ to Ψ(2S)→J/Ψ(1S)+2π in 2011. A main motivation of the present work is to predict the possible experimental detection of the decay of Ψ(2S) to J/Ψ(1S) + σ+2π, or possibly to J/Ψ(1S)+2π+glueball.

Acoustic instabilities in solid rocket motors (SRMs) can lead to severe performance deterioration and structural damage. Nozzle damping accounts for the main acoustic dissipation source, and it is highly dependent on geometric parameters and operating conditions. This study experimentally investigated the acoustic damping characteristics of submerged nozzles in SRMs, focusing on the effects of submerged cavity dimensions, nozzle convergent angle, throat-to-port area ratio, and mean pressure variations on the longitudinal instability. The steady-state wave decay method was used to quantify the acoustic damping, and a designed rotary valve system was employed to introduce periodic pressure oscillations in the high-pressure combustion chamber. The results revealed that a larger submerged cavity would reduce the nozzle damping efficiency, with the elimination of the submerged cavity enhancing the nozzle decay coefficient magnitude by 41.9%. Furthermore, increasing the nozzle convergent angle was found to amplify acoustic wave reflection, thereby diminishing damping performance. A linear inverse relationship was observed between the throat-to-port area ratio and the decay coefficient, with a 125% increase in the ratio resulting in a 24.3% reduction in the decay coefficient. Interestingly, despite the formation of complex vortices in the submerged cavity, the mean pressure variation presented negligible effects on acoustic damping characteristics, and its damping performance is similar to a simple nozzle without a cavity. These findings provide valuable experimental data for predicting the stability of a solid rocket motor with a submerged nozzle and offer insights into the optimization of submerged nozzle designs for higher acoustic damping in SRMs.

The histidine-modified EGFP was characterized as a sensing element that preferentially binds nanomolar concentrations of Cu2+ in a reversible manner (Kd = 15 nM). This research aims to determine the causes of nanomolar-affinity of this mutant by investigating significant structural and energetic alterations of the chromophore in the presence of different copper ion concentrations. In order to reveal the unknown parts of the quenching mechanism we have elaborated a specific approach that combines theoretical and experimental techniques. The theoretical experiment included the modeling of potential distortions of the chromophores and the corresponding changes in energy using quantum mechanical calculations. Differences between the modeled energy profiles of planar and distorted conformations represented the energies of activation for the chromophore distortions. We found that some values of the experimental activation energies, which were derived from fluorescence lifetime decay analysis (ex: 470 nm, em: 507 nm), were consistent with the theoretical ones. Thus, it has been revealed similarity between the theoretical activation energy (50 kJmol−1) for 40° phenolate-ring distortion and the experimental activation energy (52.17 kJmol−1) required for histidine-modified EGFP saturation with copper. This chromophore conformation was further investigated and it has been found that the large decrease in fluorescence emission is attributed to the significant charge transfer over the molecule which triggers proton transfer thereby neutralizing the cromophore.

Large wood (LW) is an indispensable element in riverine ecosystems, especially in lower river parts. The presence of LW significantly shapes local hydraulics, morphology, the nutrient budget; promotes overall river dynamics; and additionally presents a unique habitat for numerous benthic invertebrate species. Therefore, LW is recognized as valuable asset for river restoration measures. Experiences from previous projects show that ecological responses on LW implementation measures vary greatly. That complicates comparisons and estimations on the success of planned measures. Methodological inconsistencies and thus reduced transferability of the results is one major issue. Additionally, wood quality aspects are suspected to be important factors affecting benthic invertebrate colonization patterns. The focus of this study is therefore to consistently assess the ecological significance of installed LW and concrete samples of similar size and shape in terms of benthic invertebrate colonization and to further test, if the condition of wood affects the benthic invertebrate colonization. Our results show that (1) installed LW serves as an abundantly and heterogeneously colonized habitat, (2) the state of decay of LW pieces significantly affects benthic invertebrate colonization in terms of density and diversity and (3) even rare or threatened taxa closely associated to LW were abundantly present on the installed logs, emphasizing the suitability of the chosen approach.

Shrew abundance has been linked to the presence of coarse woody debris (CWD), especially downed logs, in many regions in the United States. We investigated the importance of CWD to shrew communities in managed upland pine stands in the southeastern United States Coastal Plain. Using a randomized complete block design, 1 of the following treatments was assigned to twelve 9.3-ha plots: removal (n  =  3; all downed CWD ≥10 cm in diameter and ≥60 cm long removed), downed (n  =  3; 5-fold increase in volume of downed CWD), snag (n  =  3; 10-fold increase in volume of standing dead CWD), and control (n  =  3; unmanipulated). Shrews (Blarina carolinensis, Sorex longirostris, and Cryptotis parva) were captured over 7 seasons from January 2007 to August 2008 using drift-fence pitfall trapping arrays within treatment plots. Topographic variables were measured and included as treatment covariates. More captures of B. carolinensis were made in the downed treatment compared to removal, and captures of S. longirostris were greater in downed and snag compared to removal. Captures of C. parva did not differ among treatments. Captures of S. longirostris were positively correlated with slope. Our results suggest that abundance of 2 of the 3 common shrew species of the southeastern Coastal Plain examined in our study is influenced by the presence of CWD.

Civil wars in Africa have brought many states to near collapse while many others have been plagued by political and economic failures. Studies of Africa have frequently noted the prevalence of weak and failed states. However, the notion of state failure rests more on the outcome of the political, economic, and social crises that have undermined African states, rather than the process of state failure. While the notion of state failure is a useful concept for studying the realities of war-torn African states, it is an inadequate concept to explain the conditions that lead African states into civil war. This study develops the notion of state decay and contends that it is a much more useful concept for examining the conditions that lead to civil wars and state failure in Africa.

Magnetic resonance current density imaging (MRCDI) and MR electrical impedance tomography (MREIT) are two emerging modalities, which combine weak time-varying currents injected via surface electrodes with magnetic resonance imaging (MRI) to acquire information about the current flow and ohmic conductivity distribution at high spatial resolution. The injected current flow creates a magnetic field in the head, and the component of the induced magnetic field ΔBz,c parallel to the main scanner field causes small shifts in the precession frequency of the magnetization. The measured MRI signal is modulated by these shifts, allowing to determine ΔBz,c for the reconstruction of the current flow and ohmic conductivity. Here, we demonstrate reliable ΔBz,c measurements in-vivo in the human brain based on multi-echo spin echo (MESE) and steady-state free precession free induction decay (SSFP-FID) sequences. In a series of experiments, we optimize their robustness for in-vivo measurements while maintaining a good sensitivity to the current-induced fields. We validate both methods by assessing the linearity of the measured ΔBz,c with respect to the current strength. For the more efficient SSFP-FID measurements, we demonstrate a strong influence of magnetic stray fields on the ΔBz,c images, caused by non-ideal paths of the electrode cables, and validate a correction method. Finally, we perform measurements with two different current injection profiles in five subjects. We demonstrate reliable recordings of ΔBz,c fields as weak as 1 nT, caused by currents of 1 mA strength. Comparison of the ΔBz,c measurements with simulated ΔBz,c images based on FEM calculations and individualized head models reveals significant linear correlations in all subjects, but only for the stray field-corrected data. As final step, we reconstruct current density distributions from the measured and simulated ΔBz,c data. Reconstructions from non-corrected ΔBz,c measurements systematically overestimate the current densities. Comparing the current densities reconstructed from corrected ΔBz,c measurements and from simulated ΔBz,c images reveals an average coefficient of determination R2 of 71%. In addition, it shows that the simulations underestimated the current strength on average by 24%. Our results open up the possibility of using MRI to systematically validate and optimize numerical field simulations that play an important role in several neuroscience applications, such as transcranial brain stimulation, and electro- and magnetoencephalography.