Higher Energy Levels Research Articles

Ternary Organic Solar Cells Based on S, N‐Heteroacene Non‐Fullerene Acceptors with Unfused Architecture A‐D‐D‐A‐Type

In this study, two distinct unfused non‐fullerene acceptors (NFAs) are synthesized by arranging them in an A‐D‐D‐A pattern, both containing same D‐D central S, N‐heteroacene but different terminal acceptors, namely BTA (NFA‐2) and IC (NFA‐3). Their optical and electrochemical properties are investigated. Both NFA‐2 and NFA‐3 display the high lowest unoccupied molecular orbital energy level, leading to an increased open circuit voltage in the organic solar cells. PBDB‐T is chosen as polymer donor, showing spectral absorption that complements both NFAs. The optimized organic solar cells, based on PBDB‐T:NFA‐2 and PBDB‐T:NFA‐3 attained power conversion efficiency of 9.24% and 13.50%, respectively. Since the absorption characteristics of NFA‐2 and NFA‐3 are complementary, a small amount of NFA‐2 is added into PBDB‐T:NFA‐3 binary blend, the ternary organic solar cells attained a power conversion efficiency of 15.24%. The rise in power conversion efficiency is linked to the higher values of both short circuit current and fill factor. The increased short circuit current value in ternary organic solar cells is linked to the efficient use of excitons produced in NFA‐2 by transferring energy from NFA‐2 to NFA‐3 and effective exciton dissociation, faster charge extraction, decreased bimolecular and trap‐assisted recombination. The enhanced value of FF is also linked to the processes mentioned earlier. This investigation shows that it is advantageous to use separate non‐fused NFAs with absorption spectra that complement each other and have overlapped PL spectra of a medium bandgap acceptor along with the absorption spectra of a narrow bandgap NFA in ternary organic solar cells.

Bias voltage controlled inversions of tunneling magnetoresistance in van der Waals heterostructures Fe3GaTe2/hBN/Fe3GaTe2

Abstract We report the bias voltage-controlled inversions of tunnel magnetoresistance (TMR) in magnetic tunneling junctions composed of Fe3GaTe2 electrodes and hBN tunneling barrier, observed at room temperature. The polarity reversal of TMR occurs consistently at around 0.625 V across multiple devices and temperatures, highlighting the robustness of the effect. To understand this behavior, we developed a theoretical model incorporating spin-resolved density of states (DOS) at high energy levels. By adjusting the DOS weighting at different k-points to account for misalignment between the crystal structure of electrodes in experimental devices, we improved agreement between experimental and theoretical inversion voltages. Our results provide valuable insight into the voltage-controlled spin injection and detection in two-dimensional magnetic tunnel junctions, with implications for the development of energy-efficient spintronic devices.

Light driven photoswitches: three classes of molecular systems that result in a single photoproduct via a conical intersection and an exothermic reverse reaction.

A common feature of molecular photoswitches is the selectivity of their photo-processes. The photoswitching model must combine a selective photochemical direct route and a thermal reverse reaction from the product back to the parent reactant. The conical intersection model is an appropriate approach to this problem. Valence bond analysis of the ground state reactions between the photoswitching isomers provides a chemically oriented approach to locate the conical intersection and to define its two coordinates. Three different classes of molecular photoswitches have been identified:(1) A reactant and product are connected by two distinct reaction routes with two different transition states. The conical intersection is situated inside this phase-inverting loop. An example of this class of photoswitches is an isomerization around a polar double CC, CN or NN bond. The capacity to store energy is indicated by the energy gap between the reactant and product. However, this can also result in the destabilisation of the product. For instance, the addition of bulky substituents can disrupt the planar fragment around the double bond, leading to the loss of π-conjugation. Two non-equivalent isomers with different contributions of polar and biradical forms can exhibit a highly distorted conical intersection topology. (2) The photoreaction leading to two photoproducts is a regular case. However, this case could be a "quasi single product", if two products or the parent reactant and one of the products are equivalent isomers. This is the second type of photoswitch. (3) If one of the two products is at a higher energy level than both the reactant and the main product, then this is also a possible molecular photoswitching mechanism. The second high energy product is likely to be unstable and it is close to conical intersection. The norbornadiene-quadricyclane pair is an example of this type of photoswitch.

Controlling the Crystallinity and Morphology of Bismuth Selenide via Electrochemical Exfoliation for Tailored Reverse Saturable Absorption and Optical Limiting.

As an emerging two-dimensional (2D) Group-VA material, bismuth selenide (Bi2Se3) exhibits favorable electrical and optical properties. Here, three distinct morphologies of Bi2Se3 were obtained from bulk Bi2Se3 through electrochemical intercalation exfoliation. And the morphologies of these nanostructures can be tuned by adjusting solvent polarity during exfoliation. Then, the nonlinear optical and absorption characteristics of the Bi2Se3 samples with different morphologies were investigated using open-aperture Z-scan technology. The results reveal that the particle structure of Bi2Se3 exhibits stronger reverse saturable absorption (RSA) than the sheet-like structure. This is attributed to the higher degree of oxidation and greater number of localized defect states in the particle structure than in the sheet-like structure. Electrons in these defect states can be excited to higher energy levels, thereby triggering excited-state and two-photon absorption, which strengthen RSA. Finally, with increasing the RSA, the optical limiting threshold of 2D Bi2Se3 can also be increased. This work expands the potential applications of 2D Bi2Se3 materials in the field of broadband nonlinear photonics.

Distinct Effects of Selective Sn Doping at A or B Sites in BaTiO3

The effects of selectively doping Sn into the A‐site or B‐site of BaTiO3 on its crystal structure and electronic and optical properties are systematically evaluated using first‐principles calculations, leading to several intriguing conclusions. After doping Sn at the A‐site, impurity bands originating from Sn are generated, which alter the direct bandgap to an indirect one and decrease the bandgap value, thereby reducing the electron excitation energy required. Meanwhile, (Ba0.875Sn0.125)TiO3 (A‐site) exhibits p‐type semiconductor characteristics with holes as carriers, which is beneficial for enhancing the conductivity of BaTiO3. The introduction of Sn–O interactions through A‐site Sn doping reduces the density of states of O‐2p near the valence band maximum, enhances the mobility of oxygen ions, and promotes the occurrence of redox reactions. In contrast, when Sn is doped at the B‐site, the bottom of the conduction band shifts toward higher energy levels, leading to a significant increase in the bandgap. In addition, (Ba0.875Sn0.125)TiO3 (A‐site doped) and Ba(Ti0.875Sn0.125)O3 (B‐site doped) exhibit distinct optical behaviors, thereby expanding the optical application range of BaTiO3‐based materials. This study highlights the distinct impacts of Sn doping at the A‐site or the B‐site on the modification of BaTiO3 properties, thereby paving a novel path for designing advanced materials.

Tea Tree Oil Delays Kiwifruit Ripening Through Regulating Energy Metabolism

ABSTRACTKiwifruit is easy to ripen and soften after harvest. Tea tree oil (TTO) has important application value in postharvest fruit preservation. However, the effect of TTO on kiwifruit fruit ripening, quality maintenance and energy metabolism, has not been studied. In this research, we found that TTO could delay ‘Xuxiang’ kiwifruit ripening, and keep good quality even after 18 days of storage. In three different concentrations of TTO treatments, 2.0 mL L−1 TTO has the best preservation effect on kiwifruit. TTO slowed down the softening and degreening, reduced the respiration intensity and delayed the peak of respiration. Moreover, TTO also delayed the decrease of total sugar, titratable acid (TA) and vitamin C (Vc). The fruit treated with TTO kept higher levels of ATP, ADP and energy charge (EC), and higher activities of succinate dehydrogenase (SDH), cytochrome C oxidase (CCO) and ATPase. Correlation analysis results showed that kiwifruit ripening was closely related to nutritional quality and energy metabolism. To summarize, TTO could delay kiwifruit ripening and keep fruit quality by maintaining higher energy level and activities of energy metabolism‐related enzymes during the late storage. This study will provide theoretical and technical support for kiwifruit preservation.

How does ICT Diffusion and Renewable Energy Consumption affect CO2 Emissions?

This study investigates the impact of renewable energy consumption (REC), information and communication technology (ICT), and gross domestic product (GDP) on CO2 emissions in Saudi Arabia over the period 1990-2020. Utilizing an ARDL (Autoregressive Distributed Lag) model, the results reveal that GDP exerts a positive and significant effect on emissions in both the short and long term, suggesting that economic growth is associated with higher emissions. In contrast, REC has a negative impact, indicating that increased renewable energy consumption contributes to reducing emissions over time. However, the negative effect of REC on emissions in the short term suggests that transitioning to renewable energy may involve initial costs or disruptions that temporarily affect emissions. ICT also shows a negative influence on emissions in the long term, but its short-term effects are less consistent, reflecting the potential environmental costs associated with rapid technological expansion, such as increased energy consumption and electronic waste. The interaction terms between GDP and REC, as well as GDP and ICT, reveal that higher levels of renewable energy and technological development moderate the positive relationship between GDP and emissions, highlighting the complex trade-offs between economic growth, energy transition, and technological advancement. The findings emphasize the importance of expanding renewable energy infrastructure and fostering sustainable technological innovation to mitigate emissions while sustaining economic growth in Saudi Arabia.

High triplet energy host material with a 1,3,5-oxadiazine core from a one-step interrupted Fischer indolization

Energy-efficient and deep-blue organic light-emitting diode (OLED) with long operating stability remains a key challenge to enable a disruptive change in OLED display and lighting technology. Part of the challenge is associated with a very narrow choice of the robust host materials having over 3 eV triplet energy level to facilitate efficient deep-blue emission and deliver excellent performance in the OLED device. Here we show the molecular design of new 1,3,5-oxadiazines (NON)-host materials with high triplet energy over 3.2 eV, enabling deep-blue OLED devices with a peak external quantum efficiency of 21%. A series of NON-host materials are prepared by the condensation of substituted arylhydrazines and cyclohexylcarbaldehyde in a 2:3 ratio. This straightforward “one-pot” procedure enables the formation of indoline-containing derivatives with three fused heterocyclic rings and two stereogenic centres. All materials emit UV-fluorescence in the range of 315–338 nm while possessing highly desirable characteristics for application in deep-blue OLED devices: good thermal stability, a wide energy gap (3.9 eV), a high triplet energy level of (3.3 eV), and excellent volatility during sublimation.

Changes of Intra Ocular Pressure After Nd: Yag Laser Capsulotomy in Rangpur Medical College Hospital

Background: Posterior capsule opacification is the most common disabling sequelae of modern cataract surgery. In Bangladesh we are practicing Nd: YAG laser capsulotomy in treating posterior capsule opacification. Objective: This study was carried out to evaluate intraocular pressure before and after performing Nd: YAG laser capsulotomy in posterior capsular opacification. Methods: A prospective study conducted at Ophthalmology Department, Rangpur Medical College Hospital from July to December 2018 focused on diagnosing and treating posterior capsular opacification with Nd: YAG laser of 50 patients. Patients underwent thorough ophthalmic evaluations before receiving laser treatment by a consultant ophthalmologist. Key information including patient details, pre-laser IOP measurements, laser parameters, and post-procedure IOP measurements were recorded after 60 minutes, 24 hours, 7 days, 14 days, 30 days in a specially designed proforma. Results: The baseline average IOP was 13.24. After one hour of ND: YAG Laser capsulotomy, 41 patients (82%) had raised IOP. There were no changes in IOP in 9 patients (18%). Six of the nine patients were in the 40-60 mj energy group, while three were in the 61-80 mj energy group. All patients who received high energy (81-100 mJ) had a statistically significant rise in IOP. IOP returned to baseline levels within 7 days of ND:YAG Laser capsulotomy with no intervention, and remained normal after 14 and 30 days. Conclusion: The result suggested that a transient rise of intraocular pressure occurs almost invariably. High energy level used during Nd:YAG Laser capsulotomy had significantly more chances of raised IOP. But IOP comes to almost baseline within 7 days without any interventions. It is recommended that each patient undergoing Nd:YAG laser capsulotomy should receive minimum amount of energy and patient should be followed up for rise in IOP and managed accordingly. J Rang Med Col. September 2024; Vol. 9, No. 2: 56-60

Evaluation of Gamma Irradiation Shielding Performance of Polymer Composites Doped with Chamelea Gallina Shells

This study investigates the ability of PLA/PEG blend composite materials doped with Chamelea gallina shells to protect against gamma rays. The focus of the study is to determine the effects of increasing the shells ratio on the gamma absorption coeffi-cients. The analyses measured the absorption of gamma rays at both low and high energy levels by these composites. It shows that the gamma absorption coefficient generally increases as the white sand mussel shell content increases. Especially at high ratios (such as 15%) and high gamma energies (1332.51 keV), these materials provide more effective protection at higher energy levels. These findings suggest that shells-enriched polymers can be used as potential radiation shielding materials in areas such as nuclear medicine, radiation therapy, military and space applications. It also supports the potential use of natural materials in the development of radiation shielding materials and offers new avenues for future applications.

Origin of the contrasting magnetic stability of antiferromagnetic CuMnAs and CuMnSb

Antiferromagnetic (AFM) materials exhibit great potential for next-generation spintronic applications because they have some unique characteristics compared to ferromagnetic (FM) materials. For example, the successful electrical manipulation and detection of the Néel vector at room temperature was recently realized for AFM CuMnAs in its tetragonal phase. The Néel temperature (TN) for tetragonal CuMnAs is about 480 K. In contrast, cubic half-Heusler CuMnSb, despite it is isovalent to CuMnAs, exhibits a notably lower TN of about 50 K, limiting its applicability in spintronic devices. The physical origin behind the stark difference in TN between the two compounds remains unclear. In this study, we investigate both CuMnAs and CuMnSb in both tetragonal and cubic phases. We find that the band crossing between the valence band and conduction band is more pronounced in CuMnSb compared to CuMnAs. This disparity arises from the higher energy level of the Sb 5p orbital relative to the As 4p orbital, resulting in a greater abundance of carriers in CuMnSb than in CuMnAs. Utilizing the effective band coupling model, we establish a relationship between carrier concentration and magnetic stability and confirm that the elevated carrier concentration is the origin of the weakened antiferromagnetism observed in both phases of CuMnSb.

Experimental investigation on the crashworthy performance of polyurethane foam-filled aluminum cans under repeated impact loads

Sustainable development is a development approach that focuses on economic growth and environmental protection. Substantial natural resources are consumed during the production of aluminum cans. However, recycled aluminum saves 95% of the energy needed to make new aluminum. Additionally, thin-walled tubular structures are widely used as energy absorbers. The current study developed a polyurethane foam-filled aluminum cans (PFACs) composite structure, which could be made of recycled aluminum and adopted as an energy absorber. Quasi-static test and repeated drop weight test were conducted to investigate the crushing performance and the mechanism under multiple impacts of this polyurethane foam (PU foam)-filled composite structure. A novel method which could be used to reasonably quantify their energy absorption performance was proposed to identify the densification displacement of PFACs. Quasi-static test results showed the significant effect of the PU foam filler in improving the energy absorption performance of PFACs comparing to the empty aluminum cans (EACs). Moreover, the composite effect between the aluminum can and the PU foam had a positive effect on the crashworthiness of PFACs. The repeated dynamic impact test results indicated that, compared to EACs, PFACs could withstand repeated impact loads with more repeated numbers and higher impact energy levels. These findings demonstrated PFAC is a promising energy absorber which can be used to withstand repeated impact loads.

Measurements of the Rovibrationally Dependent Lifetimes of C2 in the 13Σg+ and f3Σg- States through the VUV-Pump-UV-Probe Scheme.

The dicarbon molecule, C2, is one of the most important diatomic species in various gaseous environments. Despite extensive spectroscopic studies in the last two centuries, the radiative and photodissociative properties of C2 in its highly excited electronic states are still largely unexplored, particularly in the short vacuum ultraviolet (VUV) region. In this study, the lifetimes of C2 for rotational levels in the recently identified 13Σg+ state up to the vibrational level ν' = 4 and in the f3Σg- state up to ν' = 2 are measured for the first time with a VUV-pump-UV-probe photoionization scheme. It is found that all rovibrational levels in the f3Σg- state have lifetimes shorter than the dynamical limit of ∼4.7 ns of the present method, and the lifetimes in the 13Σg+ state show obvious and complex dependence on the rotational and vibrational quantum levels. Generally, the lifetime in the 13Σg+ state becomes shorter at higher rotational and vibrational levels, i.e., the longest lifetime measured in the ν' = 0 level is ∼18 ns, while all rotational levels in the ν' = 4 level are found to have shorter lifetimes than ∼4.7 ns. This implies that predissociation might occur and become more prominent at the higher energy levels in the 13Σg+ state. The prominent dependence of the lifetime on the rotational, vibrational and electronic level indicates complex dynamical processes in the highly excited states of C2.

Enhancing up-conversion luminescence in Yb/Er co-doped CsPbCl3 single crystals

The search for and fabrication of materials for the near-infrared range of the spectrum, including telecommunication windows, is an extremely important task in modern technology. This work presents the results of studies on the photoluminescence of CsPbCl3 single crystals with varying contents of ytterbium and erbium impurities, grown using the Bridgman method. The existence of electrically neutral Yb3+–VPb–Er3+ complexes within the crystal structure was confirmed. Resonant absorption of excitation radiation λ = 980 nm by Yb3+ ions reveals a three-step energy transfer channel from Yb3+ to Er3+ ions within a single complex. The estimated quantum yield of up-conversion luminescence at λ = 524 nm (0.02%) associated with erbium ions indicates the presence of electronic transitions to higher energy levels, with the possibility of subsequent emission within the third telecommunication window.

Maximal steered coherence in accelerating Unruh–DeWitt detectors

Quantum coherence, a fundamental aspect of quantum mechanics, plays a crucial role in various quantum information tasks. However, preserving coherence under extreme conditions, such as relativistic acceleration, poses significant challenges. In this paper, we investigate the influence of Unruh temperature and energy levels on the evolution of maximal steered coherence (MSC) for different initial states. Our results reveal that MSC is strongly dependent on Unruh temperature, exhibiting behaviors ranging from monotonic decline to non-monotonic recovery, depending on the initial state parameter Δ0. Notably, when Δ0=1, MSC is generated as Unruh temperature increases. Additionally, we observe that higher energy levels help preserve or enhance MSC in the presence of Unruh effects. These findings offer valuable insights into the intricate relationship between relativistic effects and quantum coherence, with potential applications in developing robust quantum technologies for non-inertial environments.

Research on prediction of high energy microseismic events in rock burst mines based on BP neural network

In response to the frequent occurrence of high-energy microseismic events in coal mines in China, a back propagation neural network (BPNN) prediction model based on surface subsidence data has been proposed to provide a basis for safely and efficiently predicting coal mine disasters. Theoretical research on the relationship between surface displacement, mining disturbance, and high-energy microseismic event levels has demonstrated a significant correlation among these factors. When there is a sudden increase or decrease in surface displacement or mining disturbance, the advancing working face typically exhibits dynamic characteristics. Therefore, feature parameters relevant to predicting high-energy microseismic event levels were selected as input variables for the BPNN model. Raw data from 88 sets of microseismic events in the 301 working face of the third mining area of a certain coal mine in Inner Mongolia were extracted. First, outlier preprocessing was conducted to obtain a complete dataset, which is then divided into a training set and a testing set. The BPNN model was trained with the training set and subsequently tested to evaluate its predictive performance. Finally, by comparing several model evaluation metrics, it was found that the BPNN model outperforms other common models in predicting high-energy events. The overall prediction accuracy is 86.4%, and the root mean square error (RMSE) is 0.45, indicating that the BPNN-based prediction model for high-energy microseismic events in coal mines is feasible.

Modal analysis of turbulent flows simulated with spectral element method

Leveraging the high-order nature of spectral element methods, this work introduces a methodology that enables instantaneous, local analysis of turbulent flows through a transformation to a modal space. It also introduces a dynamic explicit modal filter (DEMF) for removing the excess energy in large-eddy simulation of turbulent flows. The transformation is achieved through the application of the discrete Chebyshev transform to nodal solution values, and the resulting modes are employed to characterize and distinguish different turbulent flow properties. Implementing direct numerical simulation (DNS), a qualitative explanation of how modes can assess flow directionality and turbulence properties is provided by considering the modal representation at different locations for different turbulent flows. Additionally, reducing the resolution from DNS, it is shown how modes can qualitatively assess local flow resolvedness. A quantitative assessment of local flow resolvedness is conducted by calculating sequential energy levels from the modes and then comparing them between DNS and under-resolved cases. These energy levels correspond to different scales of motion and their behavior changes as turbulence intensifies and decays. It is observed that flow under-resolvedness manifests itself in the increased magnitudes of higher energy levels corresponding to small scales of motion. Finally, the new DEMF is discussed, which is triggered locally by comparing the local Kolmogorov length scale and the average grid spacing. The filter removes the excess energy in the detected under-resolved regions by selectively removing the energy of the modes that contribute to higher energy levels.

Typhoon‐Induced Near‐Inertial Waves Around Miyakojima Island in 2015

AbstractIn 2015, four typhoons traversed the regions surrounding the Ryukyu Island Chain, resulting in different near‐inertial waves (NIWs), the characteristics of which were investigated through in situ observations around Miyakojima Island and numerical simulations covering the East Asian marginal seas. The spatial distribution of typhoon‐induced near‐inertial motions was significantly correlated with the typhoon tracks and background currents. Typhoons Chan‐hom and Goni traversed the observation transect, resulting in different spatial patterns of NIWs owing to their different tracks. Observations on both the western and eastern sides of the Ryukyu Island Chain failed to capture NIWs after typhoon Chan‐hom, because they were positioned to the left of the typhoon track where near‐inertial motions were enhanced only in the upper 50 m. In contrast, NIWs were negligible on the left side and energetic on the right side of typhoon Goni. Despite being hundreds of kilometers from the observation transect, typhoons Soudelor and Dujuan induced NIWs with higher energy levels than those induced by typhoons Chan‐hom and Goni. The energy propagation of NIWs after typhoons Soudelor and Dujuan was significantly influenced by background currents. The western boundary currents, including the Kuroshio and Ryukyu Currents, create negative relative vorticity on their right, which works like a waveguide for the poleward advection of NIWs. However, the Ryukyu Current can be impeded by westward‐propagating cyclonic eddies from the North Pacific, which further disrupts the waveguide.

Age at first gestation in bovine influences female progeny post-weaning growth and reproductive development

This study investigated the impact of the age at which heifers conceive for the first time on the growth and reproductive development of their female offspring. A total of seven heifers pregnant at 15 months of age (15M), nine heifers pregnant at 27 months of age (27M) and seven multiparous pregnant cows (Adult) were used in the present trial. All dams were pregnant by AI from a single sire and managed in a single group during gestation, lactation and rearing stages. After weaning heifer calves were stocked on natural pastures. Progeny of heifers that gestated for the first time at different ages did not present differences in growth; however, progeny of 15 and 27M dams had reduced BW, longissimus muscle area and 12th fat thickness compared to progeny of adult dams (P < 0.05). Diameter of the largest follicle was greater in progeny born to Adult compared to progeny born to 15 and 27M (P = 0.04). Reproductive tract score (RTS) in heifers born to Adult at 399 days of age was greater compared to heifers born to 27M, and this category presented greater development than heifers born to 15M (P = 0.02). At 435 days of age, the heifers born to Adult had a greater percentage defined as pubertal compared to the progeny of 15 and 27M (P = 0.04). At 495 days of age, the weight of uterus, ovaries and corpora lutea were not affected by the age of dams at calving (P > 0.25). These data indicated that the age at which heifers received their first service affects female offspring growth RTS at early ages, but it does not have any impact in organ development after diet with a high energy level.

Dynamical quantum phase transitions in an atom-molecule system

We conduct an investigation on the dynamical quantum phase transition within an atom-molecule Bose–Einstein condensate. We explore the dynamics of atom-molecule conversion and utilize the fraction population of the atom as an order parameter for probing dynamical quantum phase transitions. It is shown that the quench dynamics of the atom presents a non-analytical change regarding the atom binding energy, and it is demonstrated that this dynamics can detect both the quantum phase transition at the ground state and at the highest energy level. Furthermore, we analyze the dynamics of the Loschmidt echo and present its connection with the dynamical quantum phase transitions.