High-resolution spectroscopy of single Pr3+^{3+} ions on the 3^3H4_4-1^1D2_2 transition

Rare earth ions in crystals exhibit narrow spectral features and hyperfine-split ground states with exceptionally long coherence times. These features make them ideal platforms for quantum information processing in the solid state. Recently, we reported on the first high-resolution spectroscopy of single Pr$^{3+}$ ions in yttrium orthosilicate (YSO) nanocrystals. While in that work we examined the less explored $^3$H$_4$-$^3$P$_0$ transition at a wavelength of 488 nm, here we extend our investigations to the $^3$H$_4$-$^1$D$_2$ transition at 606 nm. In addition, we present measurements of the second-order autocorrelation function, fluorescence lifetime, and emission spectra of single ions as well as their polarization dependencies on both transitions; these data were not within the reach of the first experiments reported earlier. Furthermore, we show that by a proper choice of the crystallite, one can obtain narrower spectral lines and, thus, resolve the hyperfine levels of the excited state. We expect our results to make single-ion spectroscopy accessible to a larger scientific community.Comment: 5 pages, 5 figure

Detection, spectroscopy and state preparation of a single praseodymium ion in a crystal

Solid-state emitters with atom-like optical and magnetic transitions are highly desirable for efficient and scalable quantum state engineering and information processing. Quantum dots, color centers and impurities embedded in inorganic hosts have attracted a great deal of attention in this context, but influences from the matrix continue to pose challenges on the degree of attainable coherence in each system. We report on a new solid-state platform based on the optical detection of single praseodymium ions via 4f intrashell transitions, which are well shielded from their surroundings. By combining cryogenic high-resolution laser spectroscopy with fluorescence microscopy, we were able to spectrally select and spatially resolve individual ions. In addition to elaborating on the essential experimental steps for achieving this long-sought goal, we demonstrate state preparation and read out of the three ground-state hyperfine levels, which are known to have lifetimes of the order of hundred seconds

How first comes energy efficiency? Assessing the energy efficiency first principle in the EU using a comprehensive indicator-based approach

The energy efficiency first (EE1) principle was defined and established as a leading principle of the European Union’s energy policy with the Clean Energy for All Europeans package in 2016. The principle requires demand resources to be considered on par with supply-side solutions and prioritized whenever they are less costly or deliver more value than alternative options. This approach should be applied in every planning process, decision-making, and investment regarding the energy sector. In order to examine to which degree the EE1 principle is actually implemented by the Member States, we developed a composite indicator, which consists of 13 criteria. These criteria capture the multiple facets of the EE1 principle and thus can also be used as a guide for the EU Member States in their operationalization of the EE1 principle. After the development of the methodology, the indicator-based approach is tested to assess the implementation of the EE1 principle in the national energy and climate plans of 14 Member States. The aim of this step is to demonstrate the feasibility of the indicator and its applicability as an assessment tool across different countries in the EU. The results imply that the fundamentals of the principle are understood and realized. Nevertheless, most countries would still fail to ensure an equal treatment between supply and demand-side resources and neglect the multiple benefits associated with energy efficiency improvements. However, those finding should be considered with caution since only limited data was used to test the operationalization of the indicator on the EE1 principle

Intensification of moisture separation in the pulp convective drying process with ultrasound-assisted method

Traditional pulp convective drying (CD) is time-consuming and energy-intensive. This study aimed to assess the drying performance of pulp using ultrasound-assisted drying (UAD) and compared it with CD to intensify moisture separation. UAD was found to be fast and efficient with high effective moisture diffusivity of 2.77 × 10–10 ∼ 3.20 × 10–10 m2/s, low activation energy of 20.2 kJ/mol, and short drying time of 21.0 ∼ 16.5 min. It demonstrated that applying ultrasound could promote moisture separation with 26 %∼42 % reductions in drying time and 42 %∼22 % savings in energy consumption. The constant rate period was not presented and no significant differences in drying rates were observed when the moisture ratio was below 0.43 under the investigated conditions. The kinetics modeling results indicated that the Page model was the best to predict the pulp drying kinetics for both methods. It may lead to an alternative efficient approach for decarbonizing the drying process in pulp and paper production

Paving the way: Analysing energy transition pathways and green hydrogen exports in developing countries – The case of Algeria

The measures needed to limit global warming pose a particular challenge to current fossil fuel exporters, who must not only decarbonise their local energy systems, but also compensate for the expected decline in fossil fuel revenues. One possibility is seen in the export of green hydrogen. Using Algeria as a case study, this paper analyses how different levels of ambition in hydrogen exports, energy efficiency and fuel switching affect the cost-optimal expansion of the power sector for a given overall emissions reduction path. Despite falling costs for photovoltaics and wind turbines, the results indicate that in countries with very low natural gas prices, such as Algeria, a fully renewable electricity system by 2050 is unlikely without appropriate policy measures. The expansion of renewable energy should therefore start early, given the high annual growth rates required, which will be reinforced by additional green hydrogen exports. In parallel, energy efficiency is a key factor as it directly mitigates CO2 emissions from fossil fuels and reduces domestic electricity demand, which could instead be used for hydrogen production. Integrating electrolysers into the power system could potentially help to reduce specific costs through load shifting. Overall, it seems advisable to analyse hydrogen exports together with local decarbonisation in order to better understand their interactions and to reduce emissions as efficiently as possible. These results and the methodology could be transferred to other countries that want to become green hydrogen exporters in the future and are therefore a useful addition for researchers and policy makers

Pain modulation by intranasal oxytocin and emotional picture viewing — a randomized double-blind fMRI study

The hormone oxytocin has been hypothesized to influence the emotional dimension of pain. This randomized, placebo-controlled, double-blind, crossover study explored whether intranasal oxytocin and emotional context can affect heat pain perception in 30 healthy male volunteers. After receiving 36 IU oxytocin or placebo, participants underwent functional Magnetic Resonance Imaging (fMRI) during which noxious and non-noxious thermode heat stimuli were applied. Simultaneously, scenes from the International Affective Pictures System (IAPS) with positive, neutral, and negative emotional valence were shown. Heat intensity and unpleasantness ratings were obtained. The activity of whole-brain correlates of heat processing was quantified via multi-voxel pattern analysis. We observed no appreciable main effects of oxytocin on ratings or neural pain correlates. Effects of emotional picture valence on ratings were smaller than reported in previous studies. Nevertheless, oxytocin was found to significantly enhance the influence of picture valence on unpleasantness ratings at noxious heat levels. No corresponding changes in whole-brain correlates of heat intensity processing were found. Our study provides evidence that intranasal oxytocin increases the effects of emotional context on the subjective unpleasantness of experimental heat pain. Future studies are needed to determine whether this effect can be utilized in clinical settings

Banning the bulb: institutional evolution and the phased ban of incandescent lighting in Germany

Much academic attention has been directed at analysing energy efficiency investments through the lens of ‘behavioural failure’. These studies have challenged the neoclassical framing of regulation which emphasises the efficiency benefits of price based policy, underpinned by the notion of rational individual self-mastery. The increasing use of a regulatory ban on electric lamps in many countries is one of the most recent and high profile flash points in this dialectic of ‘freedom-versus-the-state’ in the public policy discourse. This paper interrogates this debate through a study of electric lamp diffusion in Germany. It is argued that neoclassical theory and equilibrium analysis is inadequate as a tool for policy analysis as it takes the formation of market institutions, such as existing regulations, for granted. Further still, it may be prone to encourage idealistic debates around such grand narratives which may in practice simply serve those who benefit most from the status quo. Instead we argue for an evolutionary approach which we suggest offers a more pragmatic framing tool which focuses on the formation of market institutions in light of shifting social norms and political goals—in our case, progress towards energy efficiency and environmental goals

Identifying future district heating potentials in germany: a study using empirical insights and distribution cost analysis

District heating will play an important role in the transition towards climate-neutral heating. Various studies on modelling the energy system show that district heating and the related expansion of the networks can have different levels of importance. A main reason is that the costs for distribution grid expansion are not well or not at all considered and empirical evidence for a threshold for cost-effective distribution costs is missing in such studies. In this paper, we aim to improve empirical evidence allowing to improve the representation of future district heating expansion in energy systems models. For that, the current status of district heating is analysed in high spatial resolution for Germany. The results show that with the currently accepted average costs, a large range of the possible future market share of district heating for buildings between 17–52% is possible by 2050, with the parameters of the connection rate and the renovation rate of the building stock. We conclude that the district heating share could be increased by the factor of 2 to 5 in the future, proving the importance of climate-neutral district heating in the transition