Theoretical study of highly efficient CH3NH3SnI3 based Perovskite solar cell with CuInS2 quantum dot

Simulation studies have been carried out for n-i-p perovskite solar cell (PSC) structure i.e. ITO/SnO2/CH3NH3PbI3/CuInS2/Au. We have considered this cell as our primary structure and is simulated using Solar Cell Capacitance Simulator (SCAPS-1D) software. Here, the CuInS2 quantum dot acts as an inorganic hole transporting layer. Further, the use of the CuInS2 quantum dot in PSCs has been explored by simulating twenty different cell structures. These perovskite solar cells are based on recently used absorber layers, i.e., MASnI3, FAPbI3, and (FAPbI3)0.97(MAPbBr1.5Cl1.5)0.03, and electron transporting layers, i.e., SnO2, TiO2, ZnO, C60, and IGZO. The performance of all structures has been optimized by varying the thickness of the absorber layers and ETLs. The cell structure, ITO/SnO2/CH3NH3SnI3/CuInS2/Au, has been found to exhibit highest power conversion efficiency of 21.79% as compared to other cells. Investigations have also been carried out to analyze the effect of defect density in the absorber layer and the interface of the cell structure. In addition, the cell performance has been ascertained by examining the impact of operating temperature, metal contact work function and that of resistance in series as well as in parallel. The simulation results of our primary cell structure are found to be in good agreement with the recent experimental study.

Phonetic reduction and paradigm uniformity effects in spontaneous speech

Recent work on the acoustic properties of complex words has found that morphological information may influence the phonetic properties of words, e.g. acoustic duration. Paradigm uniformity has been proposed as one mechanism that may cause such effects. In a recent experimental study Seyfarth et al. (2017) found that the stems of English inflected words (e.g. frees) have a longer duration than the same string of segments in a homophonous mono-morphemic word (e.g. freeze), due to the co-activation of the longer articulatory gesture of the bare stem (e.g. free). However, not all effects predicted by paradigm uniformity were found in that study, and the role of frequency-related phonetic reduction remained inconclusive. The present paper tries to replicate the effect using conversational speech data from a different variety of English (i.e. New Zealand English), using the QuakeBox Corpus (Walsh et al. 2013). In the presence of word-form frequency as a predictor, stems of plurals were not found to be significantly longer than the corresponding strings of comparable non-complex words. The analysis revealed, however, a frequency-induced gradient paradigm uniformity effect: plural stems become shorter with increasing frequency of the bare stem.

Attractor Decision Network with Selective Inhibition

The ability to decide swiftly and accurately in an urgent scenario is crucial for an organism's survival. The neural mechanisms underlying the perceptual decision and trade-off between speed and accuracy have been extensively studied in the past few decades. Among several theoretical models, the attractor neural network model has successfully captured both behavioral and neuronal data observed in many decision experiments. However, a recent experimental study revealed additional details that were not considered in the original attractor model. In particular, the study shows that the inhibitory neurons in the posterior parietal cortex of mice are as selective to decision making results as the excitatory neurons, whereas the original attractor model assumes the inhibitory neurons to be unselective. In this study, we investigate a more general attractor model with selective inhibition, and analyze in detail how the computational ability of the network changes with selectivity. We proposed a reduced model for the selective model, and showed that selectivity adds a time-varying component to the energy landscape. This time dependence of the energy landscape allows the selective model to integrate information carefully in initial stages, then quickly converge to an attractor once the choice is clear. This results in the selective model having a more efficient speed-accuracy trade-off that is unreachable by unselective models.

System Level Analysis of Compressor Eye-Labyrinth Seal Rotordynamic Forces: A Computational Fluid Dynamics Approach

Accurate characterization of compressor rotordynamic coefficients during the design phase reduces the risk of sub-synchronous vibration (SSV) problems occurring in the field. Although rotordynamists extensively investigate discrete compressor components (such as seals and front shrouds) to tackle instability issues, integrated or system-level analysis of compressor rotordynamics is rare. In reality, the impeller, eye labyrinth seal, and the front shroud heavily influence one another; and the collective dynamic behavior of the system differs from the sum of the dynamic behavior of isolated components. To further investigate, a CFD-based approach is taken to evaluate the dynamic behavior of the system as a whole. The geometry and operating conditions in this work are based on the recent experimental study of Song et al. (2019) on compressor seal and front shroud stiffness values. The compressor impeller is redesigned utilizing turbomachinery design software CFturbo. The commercial CFD code CFX 19.0 is used to resolve Reynolds Averaged Navier-Stokes (RANS) equations to quantify eye labyrinth seal and front cavity stiffness, damping, and added mass, while the whole compressor stage is modeled to uncover the coupled behavior of the components, and assess the stability of the whole system instead of any discrete components. The coupled system is constructed by modeling the interacting upstream and downstream components to accurately capture key rotordynamic parameters such as damping, axial pressure, and pressure distribution evolution inside the cavities. Effect of turbulence is captured utilizing the shear stress transport (SST) k-ω model. In the current work, three CFD approaches, namely quasi-steady, transient static eccentric, and transient mesh deformation technique are tested, and predictions are made on stiffness, damping, and virtual mass. Effectiveness of each CFD method is evaluated by comparison with the experimental data. CFD results provide the non-axisymmetric pressure perturbation for the shroud and seal surfaces. Furthermore, rotordynamic coefficients are derived utilizing correlations from the literature, and compared with CFD based and experimental results.

Excited State Mechanisms in Crystalline Carbazole: The Role of Aggregation and Isomeric Defects

The molecule of Carbazole (Cz) is commonly used as a building block in organic materials for optoelectronic applications, acting as light-absorbing, electron donor and emitting moiety. Crystals from Cz and derivatives display ultralong phosphorescence at room temperature. However, different groups have reported inconsistent quantum efficiencies for the same compounds. In a recent experimental study by Liu et al. (<i>Nature Materials</i> <b>2021</b>, 20, 175-180), the ultralong phosphoresce properties of Cz have been associated with the presence of small fractions of isomeric impurities from commercially available Cz. In this paper, we use state-of-the-art computational approaches to investigate light-induced processes in crystalline and doped Cz. We revisit the role of aggregation and isomeric impurities on the excited state pathways and analyse the mechanisms for exciton, Dexter energy transfer and electron transport based on Marcus and Marcus-Levich-Jortner theories. Our excited state mechanisms provide a plausible interpretation for the experimental results and support the formation of charge-separated states at the defect/Cz molecular interface. These results contribute to a better understanding of the factors enhancing the excited state lifetimes in organic materials and the role of doping with organic molecules.

Excited State Mechanisms in Crystalline Carbazole: The Role of Aggregation and Isomeric Defects

The molecule of Carbazole (Cz) is commonly used as a building block in organic materials for optoelectronic applications, acting as light-absorbing, electron donor and emitting moiety. Crystals from Cz and derivatives display ultralong phosphorescence at room temperature. However, different groups have reported inconsistent quantum efficiencies for the same compounds. In a recent experimental study by Liu et al. (<i>Nature Materials</i> <b>2021</b>, 20, 175-180), the ultralong phosphoresce properties of Cz have been associated with the presence of small fractions of isomeric impurities from commercially available Cz. In this paper, we use state-of-the-art computational approaches to investigate light-induced processes in crystalline and doped Cz. We revisit the role of aggregation and isomeric impurities on the excited state pathways and analyse the mechanisms for exciton, Dexter energy transfer and electron transport based on Marcus and Marcus-Levich-Jortner theories. Our excited state mechanisms provide a plausible interpretation for the experimental results and support the formation of charge-separated states at the defect/Cz molecular interface. These results contribute to a better understanding of the factors enhancing the excited state lifetimes in organic materials and the role of doping with organic molecules.

THERMODYNAMICS OF THE ANTIOXIDANT ACTIVITY OF HUMULONES AND OTHER ANTIOXIDANTS FROM BEER – A MOLECULAR MODELING APPROACH

Recent experimental study identified eight potent antioxidants in German beers, including isoxanthohumol, (R)- and (S)-adhumulone, cis– and trans-iso-adhumulone, cis– and trans-iso- n-humulone, and desdimetyhyl-octahydro-iso-cohumulone. To provide insights into the structural basis of their radical scavenging activity, we calculated the thermodynamic feasibility of two common antioxidant mechanisms, hydrogen atom transfer (HAT) and single electron transfer followed by proton transfer (SET-PT), using the density functional theory (DFT) with B3LYP/6-311g++(2d,2p) method in the gas phase and implicit solvation model of water. The calculated bond dissociation enthalpies (BDEs) and ionization potential (IP) of all compounds were compared with the corresponding values for resveratrol, a highly potent antioxidant found in red wine. The fully reduced humulone isomer, desdimetyhyl-octahydro-iso-cohumulone, could scavenge free radicals via HAT as revealed by BDEs 5.1 and 23.9 kJ/mol lower than the values for resveratrol in gas phase and water, respectively. Furthermore, the enolic –OH group was identified as the pharmacophoric hotspot for the interaction of humulones with the reactive free radicals. The HAT potency of this group is significantly reduced through the formation of strong intramolecular hydrogen bond (IHB) with the β-keto group. Moreover, the SET-PT mechanism was thermodynamically favorable for isoxanthohumol. These results strongly suggest higher antioxidant activity of beers with the increased content of the reduced forms of humulones and their isomers.

The Use of ACE inhibitor/ARB in SARS-CoV-2 Patients: A Comprehensive Narrative Review

The three most common comorbidities that are associated with increased mortality in COVID-19 patients are Hypertension, Diabetes, and Cardiovascular disease, Angiotensin-converting enzyme (ACE) inhibitors and Angiotensin II receptor blockers (ARB) are the drugs most commonly prescribed for the management of these diseases. Recent experimental study in animals and humans have found that SARS-CoV-2 uses ACE2 as the receptors for entry. Moreover, in an animal study, the use of ACE inhibitor/ARB increases the level of ACE2 expression that can lead to increased SARS-CoV-2 infectivity. On the other side, some evidences suggest that the ACE2 receptor is not necessary for SARS-CoV-2 entry into the cell and suggested that there is a cofactor that play part. Experimental studies in humans also showed that there is no association between ACE inhibitor/ARB with SARS-CoV-2 infectivity and mortality. In conclusion, there is still insufficient data to stop the use of inhibitor/ARB in SARS-CoV-2 patients. Therefore, we suggested that in line with the recommendations from ESC and AHA/ACC, the use of these two drugs in SARS-CoV-2 patients with cardiovascular comorbidity should still be continued.

Invisible Higgs search through vector boson fusion: a deep learning approach

Vector boson fusion proposed initially as an alternative channel for finding heavy Higgs has now established itself as a crucial search scheme to probe different properties of the Higgs boson or for new physics. We explore the merit of deep-learning entirely from the low-level calorimeter data in the search for invisibly decaying Higgs. Such an effort supersedes decades-old faith in the remarkable event kinematics and radiation pattern as a signature to the absence of any color exchange between incoming partons in the vector boson fusion mechanism. We investigate among different neural network architectures, considering both low-level and high-level input variables as a detailed comparative analysis. To have a consistent comparison with existing techniques, we closely follow a recent experimental study of CMS search on invisible Higgs with 36 fb$$^{-1}$$ - 1 data. We find that sophisticated deep-learning techniques have the impressive capability to improve the bound on invisible branching ratio by a factor of three, utilizing the same amount of data. Without relying on any exclusive event reconstruction, this novel technique can provide the most stringent bounds on the invisible branching ratio of the SM-like Higgs boson. Such an outcome has the ability to constraint many different BSM models severely.

Passive ligament stability in natural knee: a cadaveric biomechanical study

Objectives: Applying the correct amount of collateral ligaments tension in the knees during surgery is a prerequisite to restore normal kinematics after TKA. It is well known that a low value of ligament tension could lead to an instable joint while a higher tension could induce over-tensioning and problems at later follow-up. In this study, an experimental cadaveric activity was performed to measure the minimum tension required to achieve stability in the knee joint.Methods: 10 cadaveric knee specimens were investigated in this study. The femur and tibia were fixed with polyurethane foam in specific designed fixtures and clamped to a loading frame.Increasing displacement was applied to the femoral clamp and the relative force was measured by a loading-frame machine up to the stability of the joint, determined by a decrease in the derivate of the force/displacement trend followed by a plateau.The force span between the slack region and the plateau was considered as the tension required to stabilize the joint.This methodology was applied for joints with intact cruciate ligaments, after ACL resection and after further PCL resection, to simulate the knee behavior prior a CR and a PS implant.The test was performed at 0, 30, 60 and 90° of flexion. Each configuration was analyzed three times for the sake of repeatability.Results and Conclusion: Results demonstrated that an overall tension of 41.2N (range 30.0-48.0 N) is sufficient to reach stability in a native knee with intact cruciate ligaments. Similar values appear to be sufficient also in an ACL resected knee (average 45.6, range 41.2-50.0 N), while higher tension is required (average 58.6N, range 40.0-77.0 N) were necessary in the case of PCL retention. Moreover, in this configuration, the tension required for stabilization was slighter higher at 30 and 60° of flexion compared to the one required at 0 and 90° of flexion.The results are in agreement to the ones found by other recent experimental study [Manning et al 2018 (KSSTA)] and shown that the tension necessary to stabilize a knee joint in different ligament conditions is way lower than the ones usually applied via tensioners nowadays.To reach functional stability, surgeons need to consider such results intraoperatively to avoid laxity, mid-flexion instability or ligament over-tension.