Abstract
Utilizing transaction-level financial data, we explore how household consumption responded to the onset of the COVID-19 pandemic. As case numbers grew and cities and states enacted ...shelter-in-place orders, Americans began to radically alter their typical spending across a number of major categories. In the first half of March 2020, individuals increased total spending by over 40% across a wide range of categories. This was followed by a decrease in overall spending of 25%–30% during the second half of March coinciding with the disease spreading, with only food delivery and grocery spending as major exceptions to the decline. Spending responded most strongly in states with active shelter-in-place orders, though individuals in all states had sizable responses. We find few differences across individuals with differing political beliefs, but households with children or low levels of liquidity saw the largest declines in spending during the latter part of March.
The stability of encapsulated planar-structured CH
3
NH
3
PbI
3
(MAPbI
3
) perovskite solar cells (PSCs) was investigated under various simulated environmental conditions. The tests were performed ...under approximately one sun (100 mW cm
−2
) illumination, varying temperature (up to 85 °C cell temperature) and humidity (up to 80%). The application of advanced sealing techniques improved the device stability, but all devices showed significant degradation after prolonged aging at high temperature and humidity. The degradation mechanism was studied by post-mortem analysis of the disassembled cells using SEM and XRD. This revealed that the degradation was mainly due to the decomposition of MAPbI
3
, as a result of reaction with H
2
O, and the subsequent reaction of hydroiodic acid, formed during MAPbI
3
decomposition, with the silver back contact electrode layer.
The stability of encapsulated planar-structured CH
3
NH
3
PbI
3
(MAPbI
3
) perovskite solar cells (PSCs) was investigated under various simulated environmental conditions.
A new powerful and oxidatively rugged pyrazolate-based water oxidation catalyst of formula {RuII(py-SO3)2(H2O)2(μ-Mebbp)}–, 1(H2O)2 –, has been prepared and thoroughly characterized spectroscopically ...and electrochemically. This new catalyst has been conceived based on a specific ligand tailoring design, so that its performance has been systematically improved. It was also demonstrated how subtle ligand modifications cause a change in the O–O bond formation mechanism, thus revealing the close activation energy barriers associated with each pathway.
Organic–inorganic lead halide perovskite solar cells are promising alternatives to silicon‐based cells due to their low material costs and high photovoltaic performance. In this work, thin continuous ...perovskite films are combined with copper(I) iodide (CuI) as inorganic hole‐conducting material to form a planar device architecture. A maximum conversion efficiency of 7.5% with an average efficiency of 5.8 ± 0.8% is achieved which, to our knowledge, is the highest reported efficiency for CuI‐based devices with a planar structure. In contrast to related planar 2,2′,7,7′‐tetrakis‐(N,N ‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene (spiro‐OMeTAD)‐based devices, the CuI‐based devices do not show a pronounced hysteresis when tested by scanning the potential in a forward and backward direction. The strong quenching of photoluminescence (PL) signal and comparatively fast decay of open‐circuit voltage demonstrates a more rapid removal of positive charge carriers from the perovskite layer when in contact with CuI compared to spiro‐OMeTAD. A slow response on a timescale of 10–100 s is observed for the spiro‐OMeTAD‐based devices. In comparison, the CuI‐based device displays a significantly faster response as determined through electrochemical impedance spectroscopy (EIS) and open‐circuit voltage decays (OCVDs). The characteristically slow kinetics measured through EIS and OCVD are linked directly to the current–voltage hysteresis.
Planar perovskite/copper(I) iodide solar cells with near to no J–V hysteresis, made by employing thin CuI and perovskite layers, result in a record conversion efficiency of 7.5%. The magnitude of dielectric polarization at the perovskite/hole‐conductor interface is proposed to influence the degree of J–V hysteresis.
Das Erkenntnisinteresse dieser Arbeit gilt der Notwendigkeit und Geeignetheit der Vergabe von Finanzzuweisungen zwischen den Mitgliedstaaten der Europäischen Union. Es wird der Frage nachgegangen, ...welche Wohlfahrtseffekte durch ein europäisches Finanzausgleichsystem ausgelöst werden. Da der europäische Integrationsprozeß vielgestaltigen Einfluß auf die sozio-ökonomischen Lebenslagen der Bevölkerung nimmt, wird ein Referenzrahmen entworfen, der es erlaubt, über ökonomische Kriterien hinaus auch sozio-kulturelle, rechtliche und politische Abwägungskalküle zur Bewertung der Finanzzuweisungen heranzuziehen. Die Untersuchung verdeutlicht, daß es berechtigte Argumente für einen europäischen Finanzausgleich gibt. Es zeigt sich aber auch, daß Fehlentwicklungen nicht auszuschließen sind. Ein Urteil über die Wohlfahrtseffekte der Finanzzuweisungen erfordert daher eine differenzierte (Einzelfall-)Analyse.
Device scale‐up and long‐term stability constitute two major hurdles that the emerging perovskite solar technology will have to overcome before commercialization. Here, a comparative study was ...performed between ZnO and TiO2 electron‐selective layers, two materials that allow the low‐temperature processing of perovskite solar cells on polymer substrates. Although the use of TiO2 is well established on glass substrates, ZnO was chosen because it can be readily printed at low temperature and offers the potential for the large‐scale roll‐to‐roll manufacturing of flexible photovoltaics at a low cost. However, a rapid degradation of CH3NH3PbI3 was observed if it was deposited on ZnO, therefore, the influence of the perovskite film preparation conditions on its morphology and degradation kinetics was investigated. This study showed that CH3NH3PbI3 could withstand a higher temperature on TiO2 than ZnO and that TiO2‐based perovskite devices were more stable than their ZnO analogues.
So solar: A comparison between CH3NH3PbI3/ZnO‐ and CH3NH3PbI3/TiO2‐based perovskite solar cells on polymer substrates demonstrates a higher thermal device stability if constructed on TiO2. Exacerbated degradation of CH3NH3PbI3 leads us to question the viability of ZnO as an effective electron‐selective layer in low‐temperature processed perovskite solar cells.
In biology, high valent oxo–iron(IV) species have been shown to be pivotal intermediates for functionalization of C–H bonds in the catalytic cycles of a range of O2-activating iron enzymes. This ...work details an electronic-structure investigation of FeIV(O)(LNHC)(NCMe)2+ (LNHC = 3,9,14,20-tetraaza-1,6,12,17-tetraazoniapenta-cyclohexacosane-1(23),4,6(26),10,12(25),15,17(24),21-octaene, complex 1) using helium tagging infrared photodissociation (IRPD), absorption, and magnetic circular dichroism (MCD) spectroscopy, coupled with DFT and highly correlated wave function based multireference calculations. The IRPD spectrum of complex 1 reveals the Fe–O stretching vibration at 832 ± 3 cm–1. By analyzing the Franck–Condon progression, we can determine the same vibration occurring at 616 ± 10 cm–1 in the E(d xy → d xz,yz) excited state. Both values are similar to those measured for FeIV(O)(TMC)(NCMe)2+ (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). The low-temperature MCD spectra of complex 1 exhibit three pseudo A-term signals around 12 500, 17 000, and 24 300 cm–1. We can unequivocally assign them to the ligand field transitions of d xy → d xz,yz, d xz,yz → dz2, and d xz,yz → d x2‑y2, respectively, through direct calculations of MCD spectra and independent determination of the MCD C-term signs from the corresponding electron donating and accepting orbitals. In comparison with the corresponding transitions observed for FeIV(O) (SR-TPA)(NCMe)2+ (SR-TPA = tris(3,5-dimethyl-4-methoxypyridyl-2-methy)amine), the excitations within the (FeO)2+ core of complex 1 have similar transition energies, whereas the excitation energy for d xz,yz → d x2‑y2 is significantly higher (∼12 000 cm–1 for FeIV(O)(SR-TPA)(NCMe)2+). Our results thus substantiate that the tetracarbene ligand (LNHC) of complex 1 does not significantly affect the bonding in the (FeO)2+ unit but strongly destabilizes the d x2‑y2 orbital to eventually lift it above dz2. As a consequence, this unusual electron configuration leads to an unprecedentedly larger quintet–triplet energy separation for complex 1, which largely rules out the possibility that the H atom transfer reaction may take place on the quintet surface and hence quenches two-state reactivity. The resulting mechanistic implications are discussed.
We investigate individual investors' decisions under time-varying ambiguity (VVIX) using plausibly exogenous forced mutual fund liquidations at a German brokerage. Investors reinvest 87% of forced ...liquidations when the refund occurs on a day of low ambiguity and 0% when it occurs on a day of high ambiguity. Instead of reinvesting, investors become inert and keep the refund in their cash holdings. The effect reverses approximately six months after the liquidation. If investors reinvest, they decrease their risk-taking under ambiguity. Our results are not driven by risk, rebalancing decisions, experiencing losses, or attention and are robust to alternative measures of ambiguity.
ABSTRACT
We analyze how individuals reinvest realized capital gains and losses exploiting plausibly exogenous sales due to mutual fund liquidations. Individuals reinvest 83% if a forced sale results ...in a gain relative to the initial investment; but reinvest only 40% in the event of a loss. This difference is statistically significant for more than six months and arises because many individuals forced to realize a loss choose not to reinvest anything and some even exit the stock market altogether. Individuals treat realized losses differently from paper losses and are discouraged from investing more and participating in the stock market.
The Baculovirus Expression Vector System (BEVS) is widely used to produce high amounts of recombinant proteins. Nevertheless, generating recombinant baculovirus in high quality is rather ...time-consuming and labor-intensive. Alternatively, virus-free expression in insect cells did not achieve similar expression levels for most proteins so far. The transactivation method is a promising approach for protein expression in Sf21 cells. It combines advantages of BEVS and plasmid-based expression by activating strong virus-dependent promoters on a transfected plasmid by baculoviral coinfection. Here, we identified expression elements required for transactivation. Therefore, we designed several vectors comprising different viral promoters or promoter combinations and tested them for eGFP expression using the automated BioLector microcultivation system. Remarkably, only the combination of the very late promoter p10 together with the homologous region 5 (hr5) could boost expression during transactivation. Other elements, like p10 alone or the late viral promoter polH, did not respond to transactivation. A new combination of hr5 and p10 with the strongest immediate early OpMNPV viral promoter OpIE2 improved the yield of eGFP by ~25% in comparison to the previous applied hr5-IE1-p10 expression cassette. Furthermore, we observed a strong influence of the transcription termination sequence and vector backbone on the level of expression. Finally, the expression levels for transactivation, BEVS and solely plasmid-based expression were compared for the marker protein eGFP, underlining the potential of transactivation for fast recombinant protein expression in Sf21 cells. In conclusion, essential elements for transactivation could be identified. The optimal elements were applied to generate an improved vector applicable in virus-free plasmid-based expression, transactivation and BEVS.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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