We estimate non-linear VARs to assess to what extent fiscal spending multipliers are countercyclical in the US. We deal with the issue of non-fundamentalness due to fiscal foresight by appealing to ...sums of revisions of expectations of fiscal expenditures. This measure of anticipated fiscal shocks is shown to carry valuable information about future dynamics of public spending. Results based on generalised impulse responses suggest that fiscal spending multipliers in recessions are greater than one, but not statistically larger than those in expansions. However, non-linearities arise when focusing on 'extreme' events, that is, deep recessions versus strong expansionary periods.
Adsorptive separation of olefin/paraffin mixtures by porous solids can greatly reduce the energy consumption associated with the currently employed cryogenic distillation technique. Here, the ...complete separation of propane and propylene by a designer microporous metal–organic framework material is reported. The compound, Y6(OH)8(abtc)3(H2O)6(DMA)2 (Y‐abtc, abtc = 3,3′,5,5′‐azobenzene‐tetracarboxylates; DMA = dimethylammonium), is rationally designed through topology‐guided replacement of inorganic building units. Y‐abtc is both thermally and hydrothermally robust, and possesses optimal pore window size for propane/propylene separation. It adsorbs propylene with fast kinetics under ambient temperature and pressure, but fully excludes propane, as a result of selective size exclusion. Multicomponent column breakthrough experiments confirm that polymer‐grade propylene (99.5%) can be obtained by this process, demonstrating its true potential as an alternative sorbent for efficient separation of propane/propylene mixtures.
A tailor‐made microporous metal–organic framework designed through a topologically guided secondary building unit (SBU) replacement strategy exhibits the highest selectivity for fast and efficient separation of propane and propylene via a size‐exclusion adsorption mechanism. This material, with excellent thermal and hydrothermal stability, and facile and scalable synthesis, is capable of producing polymer‐grade propylene (99.5%) from a typical propane/propylene mixture of cracking products.
We investigate the effects of a US economic policy uncertainty shock on some Euro area macroeconomic aggregates via Structural VARs. We model the indicators of economic policy uncertainty recently ...developed by Baker et al. (2013) jointly with the aggregate price indexes and alternative indicators of the business cycle for the two above indicated economic areas. According to our SVARs, a one standard deviation shock to US economic policy uncertainty leads to a statistically significant fall in the European industrial production and prices of −0.12% and −0.06%, respectively. The contribution of the US uncertainty shock on the European aggregates is shown to be quantitatively larger than the one exerted by an Euro area-specific uncertainty shock.
•We quantify the possible spillovers going from the US to the Euro area economics.•We focus on shocks to the US economic policy uncertainty.•We document a negative and significant reaction of Euro area price and quantity indicators.•The contribution of US uncertainty shock is estimated to be larger than that of a Euro-area specific uncertainty shock.
The mechanisms of CO oxidation on the Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O high-entropy oxide were studied by means of operando soft X-ray absorption spectroscopy. We found that Cu is the active metal and that ...Cu(II) can be rapidly reduced to Cu(I) by CO when the temperature is higher than 130 °C. Co and Ni do not have any role in this respect. The Cu(II) oxidation state can be easily but slowly recovered by treatment of the sample with O2 at ca. 250 °C. However, it should be noted that CuO is readily and irreversibly reduced to Cu(I) when it is treated with CO at T > 100 °C. Thus, the main conclusion of this work is that the high configurational entropy of Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O stabilizes the rock-salt structure and permits the oxidation/reduction of Cu to be reversible, thus permitting the catalytic cycle to take place.
Chemical warfare agents (CWAs) are regarded as a critical challenge in our society. Here, we use a high-throughput computational screening strategy backed up by experimental validation to identify ...and synthesize a promising porous material for CWA removal under humid conditions. Starting with a database of 2,932 existing metal–organic framework (MOF) structures, we selected those possessing cavities big enough to adsorb well-known CWAs such as sarin, soman, and mustard gas as well as their nontoxic simulants. We used Widom method to reduce significantly the simulation time of water adsorption, allowing us to shortlist 156 hydrophobic MOFs where water will not compete with the CWAs to get adsorbed. We then moved to grand canonical Monte Carlo (GCMC) simulations to assess the removal capacity of CWAs. We selected the best candidates in terms of performance but also in terms of chemical stability and moved to synthesis and experimental breakthrough adsorption to probe the predicted, excellent performance. This computational-experimental work represents a fast and efficient approach to screen porous materials in applications that involve the presence of moisture.
Two isoreticular series of pyrazolate-based 3D open metal–organic frameworks, MBDP_X, adopting the NiBDP and ZnBDP structure types H2BDP = 1,4-bis(1H-pyrazol-4-yl)benzene, were synthesized with the ...new tagged organic linkers H 2 BDP_X (X = −NO2, −NH2, −OH). All of the MBDP_X materials have been characterized through a combination of techniques. IR spectroscopy proved the effective presence of tags, while X-ray powder diffraction (XRPD) witnessed their isoreticular nature. Simultaneous TG/DSC analyses (STA) demonstrated their remarkable thermal stability, while variable-temperature XRPD experiments highlighted their high degree of flexibility related to guest-induced fit processes of the solvent molecules included in the channels. A structural isomer of the parent NiBDP was obtained with a sulfonate tagged ligand, H 2 BDP_SO 3 H. Structure solution from powder diffraction data collected at three different temperatures (room temperature, 90, and 250 °C) allowed the determination of its structure and the comprehension of its solvent-related flexible behavior. Finally, the potential application of the tagged MOFs in selective adsorption processes for gas separation and purification purposes was investigated by conventional single component adsorption isotherms, as well as by advanced experiments of pulse gas chromatography and breakthrough curve measurements. Noteworthy, the results show that functionalization does not improve the adsorption selectivity (partition coefficients) for the resolution of gas mixtures characterized by similar high quadrupole moments (e.g., CO2/C2H2); however, the resolution of gas mixtures containing molecules with highly differentiated polarities (i.e., N2/CO2 or CH4/CO2) is highly improved.
Tunable hydrophobicity: Efficient air filters for the protection against chemical warfare agents might be achieved by surface functionalization of the pores in robust metal–organic frameworks (MOFs) ...with fluoroalkyl residues and the precise control of their pore size (see picture). These MOFs capture harmful volatile organic compounds even under extremely moist conditions (80 % relative humidity).
Two highly porous coordination polymers, containing rare octanuclear hydroxo-nickel clusters and long bis-pyrazolyl spacers, are shown to possess, after mild thermal treatment, lattice cavities up to ...72% of the total crystal volume.
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