The radiative lifetime of the AΠ1/22 (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state and the related decay rate Γ=2.86(8)×107 s−1 are of relevance to the laser cooling of RaF via the optically closed AΠ1/22←XΣ1/22 transition, which makes the molecule a promising probe to search for new physics. RaF is found to have a comparable photon-scattering rate to homoelectronic laser-coolable molecules. Owing to its highly diagonal Franck-Condon matrix, it is expected to scatter an order of magnitude more photons than other molecules when using just three cooling lasers, before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the 8P3/2 state in Fr to be 83(3) ns, in agreement with literature. Published by the American Physical Society 2024

Today, more than 70 carbon pricing schemes have been implemented around the globe, but their contributions to emissions reductions remains a subject of heated debate in science and policy. Here we assess the effectiveness of carbon pricing in reducing emissions using a rigorous, machine-learningassisted systematic review and meta-analysis. Based on 483 effect sizes extracted from 80 causal ex-post evaluations across 21 carbon pricing schemes, we find that introducing a carbon price has yielded immediate and substantial emission reductions for at least 17 of these policies, despite the low level of prices in most instances. Statistically significant emissions reductions range between-5% to-21% across the schemes (-4% to-15% after correcting for publication bias). Our study highlights critical evidence gaps with regard to dozens of unevaluated carbon pricing schemes and the price elasticity of emissions reductions. More rigorous synthesis of carbon pricing and other climate policies is required across a range of outcomes to advance our understanding of "what works" and accelerate learning on climate solutions in science and policy.

A novel technique suitable for the propulsion of small unmanned aerial vehicles (UAV) is discussed in this paper. This approach utilizes the rotational energy of airborne gyro rotors and converts it into translational propulsion for the vehicle. The energy conversion is achieved by generating precisely directed centrifugal force pulses through short-duration rotor unbalances. The accurate control of the timing and magnitude of these unbalances is crucial for successful propulsion generation. Our first-order theory of controlled unbalance propulsion (CUP) predicts the potential for achieving high translational accelerations and vehicle velocities up to orbital levels. Power-saving levitation of UAVs can be attained. In this paper, we provide traceable evidence that pulsed centrifugal propulsion is based on well-established laws of physics and can be realized using state-of-the-art technologies.

Abstract Uncontrolled mine site leakage poses massive indirect environmental pollution, particularly when harmful substances, like arsenic, infiltrate water bodies, affecting humans. Arsenic contamination, recognized as a severe environmental catastrophe, exemplifies the water quality footprint from a Moroccan cobalt mine supplying electric car construction. Applying the water quality footprint method, we determined that 30 to 610 m3 of virtual dilution water per electric car would be needed to reduce arsenic pollution below natural background levels. This single mine's water quality footprint constitutes up to 0.3 % of Morocco's annual water availability, concerning all electric cars produced annually with cobalt from this mine, and corresponds to the full annual capacity of one seawater desalination plant. This underscores the risk of problem shifting with climate-friendly technologies, prompts reflection on due diligence in supply chains under German and upcoming European legislation and highlights the shared responsibility of industry, society and politics.

Additive manufacturing processes have attracted broad attention in the last decades since the related freedom of design allows the manufacturing of parts with unique microstructures and unprecedented complexity in shape. Focusing on the properties of additively manufactured parts, major efforts are made to elaborate process-microstructure relationships. For instance, the inevitable thermal cycling within the process plays a significant role in microstructural evolution. Various driving forces contribute to the final grain size, boundary character, residual stress state, etc. In the present study, the properties of commercially pure iron processed on three different routes, i.e., hot rolling as a reference, electron powder bed fusion, and laser powder bed fusion, using different raw materials as well as process conditions, are compared. The manufacturing of the specimens led to five distinct microstructures, which differ significantly in terms of microstructural features and mechanical responses. Using optical and electron microscopy as well as transmission electron microscopy, the built specimens were explored in various states of a tensile test in order to reveal the microstructural evolution in the course of quasistatic loading. The grain size is found to be most influential in enhancing the material’s strength. Furthermore, substructures, i.e., low-angle grain boundaries, within the grains play an important role in terms of the homogeneity of strain distribution. On the contrary, high-angle grain boundaries are found to be regions of strain localization. In summary, a holistic macro-meso-micro-nano investigation is performed to evaluate the behavior of these specific microstructures.

Abstract With the global population set to reach 9.7 billion by 2050, posing a potential 75% increase in food demand, this study examined the viability of edible insects as a sustainable protein source compared with beef. Employing a meta-analysis approach, data were synthesized from studies conducted over the past 13 years, using Hedges’ d effect size and mixed model methods. The parameter values included the nutritional, environmental, and economic aspects of edible insects. Out of 10,119 articles screened, 222 were selected for analysis, revealing 135 different species. Subsequently, 10 species were selected, based on the most comprehensive data available, for mixed model analysis. Although the protein content of these 10 edible insect species was generally lower than that of beef, certain species exhibited amino acid scores surpassing those of beef. Edible insects also exhibited significantly higher calcium, iron, and zinc content compared with beef. Environmental aspects may enhance the value of edible insects as they exhibited greater advantages compared with beef. Despite some identified risks in incorporating edible insects into the diets of humans and animals, there remain potential areas for further investigation and development, such as addressing fat content, indigestible carbohydrate, availability, and sustainability aspects. Further research is required to promote local edible insect products as nutritious food and feed.

Research into novel materials with tailored properties is essential to improve CO2 adsorption and activation, a fundamental preliminary phase in catalytic CO2 conversion processes. Here, we have employed density functional theory-based calculations to investigate CO2 activation over the pristine and Cu-decorated carbon-based two-dimensional material ψ-graphene and its hydrogenated forms, i.e. ψ-graphone (half hydrogenated) and ψ-graphane (fully hydrogenated). ψ-graphene is a metallic allotrope of graphene containing 5-6-7 membered carbon rings. Our study found exothermic binding of CO2 at all three materials (for both pristine and Cu-decorated materials), indicating spontaneous physisorption. The presence of a single Cu atom plays a significant role in increasing the activity of ψ-graphene towards CO2 activation. By decorating ψ-graphene with Cu atoms, the adsorption energy at ψ-graphene increases about three times, whereas no significant variation is observed on ψ-graphone and ψ-graphane sheets. We used Bader charge analysis and electronic density of states plots to further quantify the nature of the interaction between CO2 and these materials.

AbstractReforestation after forest clear‐cutting is an effective measure to increase soil organic carbon (SOC) sequestration; still, the soil C balance under reforestation and the role of microbial communities in that process remain to be determined. Samples of organic (0–2 cm) and mineral (2–10 cm) horizons were collected from the 7‐, 15‐, 20‐, 29‐, and 36‐year‐old forest stands of Chinese fir (Cunninghamia lanceolata) after plantation clear‐cutting in subtropical zone under the condition of phosphorus limitation. Particulate organic carbon (POC), mineral‐associated organic carbon (MAOC), microbial phospholipid fatty acids (PLFAs), and enzymatic activities for C, nitrogen (N), and phosphorus (P) acquisition were analyzed. The lowest contents of POC (10%) and MAOC (13%) in the organic horizon were found in 7‐year‐old stands due to the slow tree regrowth and extensive decomposition of SOC in the first years of forest regrowth. POC (2.0×) and MAOC (0.8×) increases in the organic horizon with forest age were attributed to the stand development and accumulation of above‐ and belowground litter. The organic horizon had a higher POC:MAOC ratio than the mineral (0.7–1.1 vs. 0.2–0.5), indicating lower SOC stability in the first one. The ratio of POC:MAOC increased with the Gram‐positive to Gram‐negative bacteria (G+:G‐) ratio, pointing out that microbial communities developed a specific community structure and substrate utilization strategies of organic matter under plantation restoration. The increase of total PLFAs and the G+:G‐ ratio was closely linked with the microbial C and P limitations, indicating that microorganisms shifted community structure to slow‐growing species and increased their content to cope with the C and P restrictions. In the soils of young plantations, microorganisms were limited by C and P; however, the C limitation was alleviated in the 36‐year‐old plots in the organic horizon due to increased litter input, whereas the P limitation was not. This discrepancy between C and P limitation suppressed the decomposition of litter entering the soil, which was seen in decreased specific activity of C degrading enzymes and led to the accumulation of POC in the organic horizon. Thus, soil C sequestration under reforestation of Chinese fir can be controlled by the amount of litter entering the soil and by metabolic C, N, and P limitations that force microorganisms to shift community structure and change their activity.

In this paper, we study the consequences of the fundamental theorem of calculus from an algebraic point of view. For functions with singularities, this leads to a generalized notion of evaluation. We investigate properties of such integro-differential rings and discuss many examples. We also construct corresponding integro-differential operators and provide normal forms via rewrite rules. They are then used to derive several identities and properties in a purely algebraic way, generalizing well-known results from analysis. In identities like shuffle relations for nested integrals and the Taylor formula, additional terms are obtained that take singularities into account. Another focus lies on treating basics of linear ODEs in this framework of integro-differential operators. These operators can have matrix coefficients, which allow to treat systems of arbitrary size in a unified way. In the appendix, using tensor reduction systems, we give the technical details of normal forms and prove them for operators including other functionals besides evaluation.

In the plastics industry, CFD simulation has been used for many years to support mold design. However, using simulation as a substitute for experimentation remains a major challenge to this day. This is due to the unknown congruence between simulation and experiment. The present work focuses on a comparison between simulation (generated with the software Moldflow Insight Ultimate from Autodesk Inc., San Francisco, CA, USA) and experiment by using molds of different complexity, where, in contrast to a large number of previous investigations, both the characteristics of the parts and the time series of the process parameters were compared with each other. For this purpose, the high-resolution time series of the process parameters injection pressure, flow rate, and cavity pressure as well as the mass and the dimensions of the manufactured parts were acquired during the experiments and the results were compared with the computations obtained from the simulation. In addition, potential causes like the material data, mesh and solver parameter, and the machine-specific behavior were analyzed to assess which of these causes may be decisive for a deviation between simulation and experiment.