Energy Dependence Research Articles

The implementation of an optimized neural network in a hybrid system for energy management

In the face of increasing global energy demand and volatile energy prices, many countries are searching for solutions to ensure their energy independence. One of the most popular solutions is to incorporate renewable energy sources in their energy systems. While there are many advantages to integrating renewable energy sources, it is important to note that their intermittent operation can present challenges. Energy storage and smart grid management systems are key solutions to overcome these challenges and ensure sustainable, reliable use of renewable energy sources. In this article, we present an intelligent electrical energy management system for hybrid energy systems. This management system is based on a multi-layer neural network that has undergone an architecture optimization phase to improve the accuracy of real-time energy management and simplify its implementation. The management model that was built demonstrated highly good performance across a range of test circumstances.

Life Cycle Analysis of a Battery Energy Storage System

For Latvian government and transmission system operator energy security and independence has been an issue for a period of time, even more when political situation changed, motivating to act faster in order to swich off from BREL system completely. Therefore, three Baltic states have made an agreement on building more stable electricity transmission system within Baltic region and to connect with European transmission systems, building new stations with synchronous compensators and energy storage systems. In order to build a system, that allows to include more energy from renewable resources and secure possible disbalances in system, Latvian TSO operator is building a new battery energy storage system. This paper is aimed to look at what are the costs of this battery energy storage system from climate perspective to Latvia and its society in order to gain energy security and possibility to include more energy from renewable resources.

Recovery of the X-ray polarisation of Swift J1727.8−1613 after the soft-to-hard spectral transition

We report on the detection of X-ray polarisation in the black-hole X-ray binary Swift J1727.8$-$1613 during its dim hard spectral state by the Imaging X-ray Polarimetry Explorer (IXPE). This is the first detection of X-ray polarisation at the transition from the soft to the hard state in an X-ray binary. We find an averaged 2--8 keV polarisation degree of $(3.3 0.4)\, <!PCT!>$ and a corresponding polarisation angle of $3 which matches the polarisation detected during the rising stage of the outburst, in September--October 2023, within $1 uncertainty. The observational campaign complements previous studies of this source and enables comparison of the X-ray polarisation properties of a single transient across the X-ray hardness-intensity diagram. The complete recovery of the X-ray polarisation properties, including the energy dependence, came after a dramatic drop in the X-ray polarisation during the soft state. The new IXPE observations in the dim hard state at the reverse transition indicate that the accretion properties, including the geometry of the corona, appear to be strikingly similar to the bright hard state during the outburst rise despite the X-ray luminosities differing by two orders of magnitude.

Techno-economic and environmental analysis for the application of renewable energy sources in seaports.

Ports have an indisputable effect on the decarbonization of urban areas, helping to minimize air and environmental pollution and achieve sustainable development. In this instance, it is crucial to do research that can advance our understanding of how to increase ports' energy independence by utilizing renewable energy sources. The current study aims to study the environmental benefits and techno-economic challenges of converting three Egyptian ports to eco-friendly green ports by using solar panels, offshore wind turbines, and hydrogen fuel cells. The study shows that from a technical point of view, the required green power to be installed at Alexandria, Port Said, and Suez ports is around 13 MW, 5 MW, and 1.5 MW, respectively. Furthermore, the environmental analysis findings demonstrate that integrating green energy will significantly lower emissions in seaports. It is anticipated that the ports of Alexandria, Port Said, and Suez will achieve annual reductions in carbon dioxide emissions of roughly 68,7 k-tons, 25,8 k-tons, and 6,4 k-tons, respectively. From an economic point of view, the ports could be supplied with green energy from wind turbines for a cost of between 0.115 and 0.125 USD/kWh, while solar panels have a cost range of 0.098 to 0.129 USD/kWh. Additionally, hydrogen fuel cell systems cost about 0.102 USD/kWh.

Energy dependence of GafChromic LD-V1 film dose response to X-ray photons in the 60 to 180 kV range

Abstract Introduction: Radiochromic film (RCF) is suitable for use as a dosimeter owing to its inherently superior spatial resolution and near-water equivalence. A new model of RCF recommended for measuring imaging dose in the kV nominal energy range was recently introduced onto the market. In this study, we investigate the dependence on the beam quality of GafChromic LD-V1 film’s radiation dose response. Material and methods: Pieces of LD-V1 film were irradiated to air kerma ranging from 0 to 570 mGy in X-ray photons with beam qualities of 60 kV (HVL = 1.32 mm Al), 100 kV (HVL = 2.83 mm Al), 120 kV (HVL = 5.11 mm Al), 150 kV (HVL = 6.23 mm Al), and 180 kV (HVL = 0.54 mm Cu). The net reflectance from each film was obtained from a color flatbed scanner. For each beam quality, an analytical power function was fitted to the net reflectance - air kerma relationship and tested for differences. Results: We have found that for the beam qualities investigated, the response of the Gafchromic LD-V1 film was not significantly dependent on energy, and a single calibration curve could be used. The total relative uncertainty and absolute error reached maxima of 18% and 80%, respectively for air kerma values less than 50 mGy, and remained below 10% for air kerma in the range 50 mGy to 570 mGy. Conclusions: The results of our investigation revealed that the response of Gafchromic LD-V1 film is not significantly dependent on beam quality. A minimum air kerma irradiation of 50 mGy is recommended to minimise uncertainty.

THE MAIN OBJECTIVES OF THE EUROPEAN UNION'S (EU) SPECIAL STRATEGY FOR CENTRAL ASIA (2007–2013)

The article examines the European Union's approach to Central Asia from 2007 to 2013, highlighting key objectives and initiatives designed to strengthen cooperation between the EU and nations in the region. This strategy encompasses a diverse range of issues, including economic growth, governance, energy security, educational development, and regional collaboration. The overarching goals of the strategy include: Economic Development: The strategy emphasizes the importance of economic partnerships, trade, and investment in promoting growth and integration of the region into the global economy. Governance and Anti-Corruption: The European Union supports governance and anti-corruption reforms that are essential for sustainable development. Energy Security: Given the significant energy resources in Central Asia, measures have been taken to diversify energy sources and increase the EU's energy independence. Education: Educational programs and initiatives aim to improve skills of the population and develop human capital in the region. Regional Cooperation: The EU actively promotes regional cooperation among Central Asian countries to contribute to peace and stability in the region. The article emphasizes the flexibility and adaptability of the EU's approach to the challenges and changing circumstances in the region. This demonstrates the European Union's commitment to playing a proactive role in promoting positive development in Central Asia and creating the conditions for long-term collaboration and shared prosperity.

#1492 Metabolic switch in CD8+ T cells may influence immune response in chronic antibody-mediated rejection (CAMR)

Abstract Background and Aims CAMR is the main cause of chronic graft injury and subsequent graft loss, but its pathogenesis is still largely unclear. Our group demonstrated an increase in CD8+ T cells infiltrating biopsies from CAMR patients (PMID: 20595199), but their role remains to be defined. Recently, immunometabolism has emerged as a field connecting cell energy metabolism with the immune cell differentiation and functions. Particularly, the permanent aerobic glycolysis of CD8+ lymphocytes induces their transition from naïve to activated state and effector T cells (PMID: 37315709). Thus, the aim of the study was to investigate the molecular mechanisms underlying the development of CAMR by the analysis of gene expression profiles of CD8+ T lymphocytes in conjunction with their metabolic state. Method We enrolled 14 patients with biopsy-proven CAMR and 12 stable transplant recipients with normal graft histology and function (control group). CD8+ T cells were purified by CD8 MicroBeads (Miltenyi Biotec) then counted (TC20™ Automated Cell Counter). Gene expression profiles of CD8+ T lymphocytes isolated from both groups were assessed using Agilent microarrays. Data obtained were statistically and functionally evaluated (IPA software) and validated by qPCR. Oxygen consumption rate (OCR) in CD8+ and CD8- cells was measured by a Resipher oxygen sensing lid (Lucid Scientific Inc., USA). The contribution of mitochondrial respiration to OCR was investigated in isolated CD8+ T cells from CAMR and controls treated with rotenone/antimycin A (Rot/AA), oligomycin (Olygo) or carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) to evaluate spare respiratory capacity (SRC), ATP-linked respiration, proton leak and maximal respiration. Results Gene expression profiles of CD8+ T cells showed a characteristic alteration of lipid metabolism in CAMR patients with the triglyceride biosynthesis pathway (p = 2.69E-3) as the most altered pathway and several genes de-regulated all potentially involved in the altered metabolic state of CD8+ T cells. Among others, we validated the increased expression of Nicotinamide Phosphoribosyltransferase (NAMPT) (FC = +2.39), the rate-limiting enzyme of nicotinamide adenine dinucleotide (NAD+) salvage pathway involved in the glycolysis progression, mostly activated in effector T cells. We then decided to evaluate the OCR and the metabolic state of CD8+T cells. Basal OCR was higher in CD8+ rather than CD8- cells, but with different trends among cells isolated from control and CAMR patients. Indeed, CD8+ cells from CAMR patients showed higher OCR compared to control, while OCR was lower in CD8- from CAMR rather than control patients. CD8+ OCR from both CAMR and control patients was mostly dependent on mitochondrial respiration, since it was deeply reduced by Rot/AA treatment. Interestingly, inhibitory response to Oligo treatment by CD8+ cells from CAMR patients was modest, while OCR was noticeably stimulated by FCCP in these cells, suggesting that mitochondrial oxygen uptake was not ATP linked but rather associated with increased uncoupling. These data suggest that CD8+ T cells from CAMR patients are activated effector T cells primarily utilizing aerobic glycolysis. To confirm this hypothesis, we evaluated the gene expression levels of: i) HIF1a, which involves permanent dependence on glycolysis even in the presence of oxygen (Warburg effect); ii) fatty acid transporter CD36, whose levels mimic an energy dependence on the beta oxidation of fatty acids, a process activated in memory T cells. We confirmed an increased expression of HIF1a and a reduced expression of CD36 in CD8+T cells from CAMR patients compared to controls (p<0.05), that confirm the T effector phenotype. Conclusion Our data suggest that CD8+ T cell from CAMR patients showed permanent dependency on glycolysis leading to altered immune phenotype and response, thus indicating novel opportunities to modulate the immune system for therapeutic purposes in kidney transplanted patients and reduce graft rejection.

The Activation Energy Temperature Dependence for Viscous Flow of Chalcogenides

For some chalcogenide glasses, the temperature dependence of the activation energy E(T) of viscous flow in the glass transition region was calculated using the Williams–Landel–Ferry (WLF) equation. A method for determining the activation energy of viscous flow as a function of temperature is proposed using the Taylor expansion of the function E(T) using the example of chalcogenide glasses As-Se, Ge-Se, Sb-Ge-Se, P-Se, and AsSe-TlSe. The calculation results showed that the temperature dependence of the activation energy for the Ge-Se, As-Se, P-Se, AsSe-TlSe, and AsSe systems is satisfactorily described by a polynomial of the second degree, and for Sb-Ge-Se glass by a polynomial of the third degree. The purpose of this work is to compare the values of the coefficients obtained from the Taylor series expansion of E(T) with the characteristics of the E(T) versus (T − Tg) curves obtained directly from the experimental temperature dependence of viscosity. The nature of the dependence E(T) is briefly discussed.

Prediction of giant anomalous Nernst effect in Sm(Co,Ni)5

Sm-Co bulk alloys are well-known permanent magnets having large remanent magnetizations and coercive forces and are widely used in many industrial products. Recently, a large transverse thermoelectric conversion was observed for SmCo5 over a wide temperature range in the absence of magnetic fields. The large thermoelectric conductivity tensors (αxy) was also confirmed by the first-principles density functional theory (DFT) calculations. In this study, we predicted further enhancement of the αxy by including Ni in Co site of SmCo5. We showed that the αxy of Sm(Co1−xNix)5 increases with increasing the Ni ratio and takes the maximum value αxy = 11.3 A K−1 m−1 around x = 0.08 at 300 K, which is about 77% enhancement of αxy = 6.4 A K−1 m−1 in SmCo5. We clarified that the band proximity points near the nodal line of Sm(Co0.92Ni0.08)5 are the main contributing factor to the large Berry curvature, providing the steep slope of the energy dependence in the anomalous Hall conductivity around the Fermi energy.

Comparative study on physical properties of bio-based PA56 fibers and wearability of their fabrics

Abstract Bio-based polyamide 56 (PA56) has significant advantages in reducing oil dependence and reducing carbon emissions. This study compared the physical properties of bio-based PA56 and conventional polyamide 66 (PA66) fibers and their fabrics. The results showed that due to the odd arrangement structure of carbon atoms in PA56 fiber molecules, its crystallinity and orientation were lower than those of PA66. At the same time, PA56 had a higher degradation rate and coloring rate due to its smaller crystallinity and higher moisture content and gave PA56 fabrics better instantaneous cooling and moisture absorption and drying properties. In addition, the molecular structure characteristics of PA56 also lead to a lower stiffness and soft feel of the fabric, which is beneficial for improving the curling phenomenon of the fabric. Overall, bio-based PA56 fibers can meet the applications in the textile and clothing field and can largely replace PA66, which is worthy of further research and utilization.

Electron beam response corrections for an ultra-high-dose-rate capable diode dosimeter.

Ultra-high-dose-rate (UHDR) electron beams have been commonly utilized in FLASH studies and the translation of FLASH Radiotherapy (RT) to the clinic. The EDGE diode detector has potential use for UHDR dosimetry albeit with a beam energy dependency observed. The purpose is to present the electron beam response for an EDGE detector in dependence on beam energy, to characterize the EDGE detector's response under UHDR conditions, and to validate correction factors derived from the first detailed Monte Carlo model of the EDGE diode against measurements, particularly under UHDR conditions. Percentage depth doses (PDDs) for the UHDR Mobetron were measured with both EDGE detectors and films. A detailed Monte Carlo (MC) model of the EDGE detector has been configured according to the blueprint provided by the manufacturer under an NDA agreement. Water/silicon dose ratios of EDGE detector for a series of mono-energetic electron beams have been calculated. The dependence of the water/silicon dose ratio on depth for a FLASH relevant electron beam was also studied. An analytical approach for the correction of PDD measured with EDGE detectors was established. Water/silicon dose ratio decreased with decreasing electron beam energy. For the Mobetron 9 MeV UHDR electron beam, the ratio decreased from 1.09 to 1.03 in the build-up region, maintained in range of 0.98-1.02 at the fall-off region and raised to a plateau in value of 1.08 at the tail. By applying the corrections, good agreement between the PDDs measured by the EDGE detector and those measured with film was achieved. Electron beam response of an UHDR capable EDGE detector was derived from first principles utilizing a sophisticated MC model. An analytical approach was validated for the PDDs of UHDR electron beams. The results demonstrated the capability of EDGE detector in measuring PDDs of UHDR electron beams.

What determines local attitudes towards Jordan’s renewable energy transition? Evidence from household surveys

ABSTRACT The potential for renewable energy to encourage sustainable development raises high hopes for the future among countries in the Global South. However, there has been less research on how energy transitions are perceived outside of the Global North and democratic contexts. This paper explores attitudes towards the energy transition in Jordan, where expert interviews reveal that a strong renewable energy industry has emerged from top-down government efforts to reduce energy dependency and costs. We perform an in-person household survey with 320 respondents in areas with different transition risks and benefits, and then test a series of hypotheses using regression analysis. In the four communities surveyed, income stress and climate concern influence attitudes, as well as perceptions of community benefits. National-level concerns also matter, including energy dependency and energy costs for all Jordanians. Our results highlight the importance of context: findings from the North are not universal and understanding transitions in the Global South requires studying them in their own right. Policy insights Jordanian policymakers should reverse their policy of blocking renewables to avoid public backlash. Jordanian policymakers and funders should promote projects in communities with high economic dependence on the fossil fuel industry to ensure local support in areas facing transition risks. Policymakers should highlight collective, not just individual benefits of transitions, as perceptions of community and country benefits increase support. Policymakers in highly energy-dependent countries like Jordan should frame renewables as an answer to local and national challenges such as high energy prices. Actors wishing to promote clean energy support in different contexts should investigate local dynamics to build communication strategies that frame transitions appropriately.

Absorption Correction for 3D Elemental Distributions of Dental Composite Materials Using Laboratory Confocal Micro-X-ray Fluorescence Spectroscopy.

Confocal micro-X-ray fluorescence (micro-XRF) spectroscopy facilitates three-dimensional (3D) elemental imaging of heterogeneous samples in the micrometer range. Laboratory setups using X-ray tube excitation render the method accessible for diverse research fields but interpretation of results and quantification remain challenging. The attenuation of X-rays in composites depends on the photon energy as well as on the composition and density of the material. For confocal micro-XRF, attenuation severely impacts elemental distribution information, as the signal from deeper layers is distorted by superficial layers. Absorption correction and quantification of fluorescence measurements in heterogeneous composite samples have so far not been reported. Here, an absorption correction approach for confocal micro-XRF combining density information from microcomputed tomography (micro-CT) data with laboratory X-ray absorption spectroscopy (XAS) and synchrotron transmission measurements is presented. The energy dependency of the probing volume is considered during the correction. The methodology is demonstrated on a model composite sample consisting of a bovine tooth with a clinically used restoration material.

Expanding Electric Vehicle Adoption in Disadvantaged Communities

To achieve ambitious electric vehicle (EV) and equity goals, sales must reach beyond general populations and into priority groups. Better understanding of EV adoption by priority populations can inform strategies to expand it. We examine light-duty EV adoption in state-designated disadvantaged communities (DACs) in New York State (NYS). We analyze 5,097 survey responses from 21,843 consumers rebated for 2017–2019 EV purchases/leases. We use descriptive statistics, logistic regressions, and dominance analysis to identify and rank order factors associated with DAC adopters. Descriptively, demographic and related findings were largely consistent with expectations based on previous studies. In this study, DAC adopters were also compared with NYS market baseline statistics. They were found to resemble mainstream new vehicle buyers more closely than non-DAC adopters and, indeed, they already represent progress “beyond” the mainstream in several respects. For the logistic regressions, in addition to several expected findings (e.g., more frequent renting and apartment dwelling), factors that distinguished DAC adopters included the following: rebated EVs were household additions (as opposed to replacements), non-Tesla battery EVs, and/or purchased (as opposed to leased); the importance of charging and/or environmental impacts; and/or the unimportance of energy independence. Factors surprisingly not associated with DAC residence included the following: race/ethnicity; importance of various incentives; and/or awareness of rebates from consumers and dealers. Indeed, in contrast to a previous analysis for California, no enabling or awareness factors were found to help distinguish DAC adopters from non-DAC adopters, including financial considerations, when controlling for other factors such as income. Findings are discussed and compared with previous research, and observations are provided to inform program design and outreach.

METHODS AND TOOLS FOR IN-DEPTH ANALYSIS OF ENERGY CHARACTERISTICS AND MANAGEMENT OF ENERGY CONSUMPTION IN EDUCATIONAL INSTITUTIONS

A factor of the state's national security is reducing energy dependence and taking measures to increase energy efficiency, especially in the budgetary sphere, because about 90% of such buildings do not meet modern energy efficiency requirements. Creating a reliable energy consumption management system, choosing measures to reduce consumption and diversifying energy sources is a difficult task that requires consideration of building energy consumption processes as a complex problem with the use of modern tools of the energy management system, modeling, and the use of modern approaches to automation and measurements. The object of research is energy consumption processes in educational institutions. The subject of the research is energy characteristics and methods of energy consumption management in educational institutions. Research methods. analytical methods, system analysis, synthesis, modeling, systematization, method of comparative and structural analysis. One of the tasks of this study is to review the capabilities of software products that can be used by energy managers of educational institutions to monitor, analyze and forecast energy consumption, as well as to create reports. Also in the work, an analysis of the state of affairs regarding energy consumption management was carried out on the example of KPI named after Igor Sikorskyi; proposals for the development of the automated energy monitoring system were provided, in particular, the architecture of the web application was developed taking into account the support of existing databases to improve the energy monitoring process.

Operative Benefits of Residential Battery Storage for Decarbonizing Energy Systems: A German Case Study

The reduction in PV prices and interest in energy independence accelerate the adoption of residential battery storage. This storage can support various functions of an energy system undergoing decarbonization. In this work, operative benefits of storage from the system perspective, namely, generation cost reduction and congestion mitigation, are investigated. Germany is chosen as a case study due to its strong reliance on variable renewable energy. For the analysis, an economic dispatch model with a high spatial resolution is coupled with a pan-European transmission grid model. It is shown that the system’s generation costs are highest when the assets are used only to maximize PV self-consumption, and the costs are lowest when the storage also reacts to the market dynamics. This amounts to a 6% cost reduction. Both operation strategies result in an equal level of grid congestion and infrastructure loading. This is improved with a strategy that accounts for regional peak reduction as a secondary objective. The high congestion level emphasizes that grid expansion needs to keep pace with the generation and electrification expansion necessary to decarbonize other sectors. Lastly, policymakers should enable multipurpose utilization, e.g., via the introduction of market-oriented retail electricity prices with intervention options for grid operators.

Quantum dynamics of the P(2D) + H2 (X1[formula omitted]) → PH (X3Σ-) + H(2S) reaction

The title reaction is thought to be important for the astronomical PO formation, which may contribute to the generation of bioavailable H3PO3. Using quasi-classical trajectory (QCT) method, the state-specified (v = 0, j = 0) rate constant of this reaction was calculated. The comparison with previous temperature-averaged QCT rate constant shows that the effect of ro-vibrational excitation is relatively small below 2000 K. Then, the time-dependent wave packet (TDWP) method was applied to investigate the quantum reaction mechanisms, obtaining the state-specified (v = 0, j = 0) reaction probability, integral cross sections and rate constants. The number of partial waves and the integral interval of collision energy considered were rigorously tested to ensure the convergence of the TDWP rate constant below 2000 K. The TDWP rate constant agrees better to the latest experimental results at 291 to 685 K than those from the two QCT calculations. Also, the TDWP calculations can produce relatively reliable rate constants at 700 to 2000 K, where the Arrhenius formula fitted by experimental results ignores the temperature dependence of the activation energy. The calculated rate constants are helpful for modelling the phosphorus chemistry and determining the abundances of the P-bearing species in interstellar media (ISM).

Caught in the liberal pragmatic trap? How political parties viewed energy dependence on Russia in three European countries 2012–2022

Caught in the liberal pragmatic trap? How political parties viewed energy dependence on Russia in three European countries 2012–2022

Constraints on dark matter and astrophysics from tomographic γ -ray cross-correlations

We study the cross-correlation between maps of the unresolved γ-ray background constructed from the 12-year data release of the Large-Area Telescope, and the overdensity of galaxies in the redshift range z≲0.4 as measured by the 2MASS photometric redshift survey and the WISE-SuperCOSMOS photometric survey. A signal is detected at the 8−10σ level, which we interpret in terms of both astrophysical γ-ray sources, and weakly interacting massive particles (WIMP) dark matter decay and annihilation. The sensitivity achieved allows us to characterise the energy and redshift dependence of the signal, and we show that the latter is incompatible with a pure dark matter origin. We thus use our measurement to place an upper bound on the WIMP decay rate and the annihilation cross section, finding constraints that are competitive with those found in other analyses. Our analysis is based on the extraction of clean model-independent observables that can then be used to constrain arbitrary astrophysical and particle physics models. In this sense we produce measurements of the γ-ray emissivity as a function of redshift and rest-frame energy ϵ, and of a quantity F(ϵ) encapsulating all WIMP parameters relevant for dark matter decay or annihilation. We make these measurements, together with a full account of their statistical uncertainties, publicly available. Published by the American Physical Society 2024

Internal Energy Dependence of the Pyrrole Dimer Cation Structures Formed in a Supersonic Plasma Expansion: Charge-Resonance and Hydrogen-Bonded Isomers.

The structures of the pyrrole dimer cation (Py2+) formed in an electron-ionization-driven supersonic plasma expansion of Py seeded in Ar or N2 are probed as a function of its internal energy by infrared photodissociation (IRPD) spectroscopy in a tandem mass spectrometer. The IRPD spectra recorded in the CH and NH stretch ranges are analyzed by dispersion-corrected density functional theory (DFT) calculations at the B3LYP-D3/aug-cc-pVTZ level. The spectra of the cold Ar/N2-tagged Py2+ clusters, Py2+Ln (n = 1-5 for Ar, n = 1 for N2), indicate the exclusive formation of the most stable antiparallel π-stacked Py2+ structure under cold conditions, which is stabilized by charge-resonance interaction. The bare Py2+ dimers produced in the ion source have higher internal energy, and the observation of additional transitions in their IRPD spectra suggests a minor population of less stable hydrogen-bonded isomers composed of heterocyclic Py/Py+ structures formed after intramolecular H atom transfer and ring opening. These intermolecular isomers differ from the chemically bonded structures proposed earlier in the analysis of IRPD spectra of Py2+ generated by VUV ionization of neutral Pyn clusters.