פרסומים

Drastic changes in open-circuit voltage decay (OCVD) response time in CH3NH3PbX3 perovskites have been systematically investigated in order to elucidate the dynamic properties of the interface. Under pre-illumination treatment, the decay times are reduced by orders of magnitude, but if left to rest for sufficient time, the solar cell evolves to its original decay kinetics. In order to explain these observations, we developed advanced modeling of the perovskite solar cell to obtain a realistic description of the immediate vicinity of the interface, including ionic variable concentration and accumulation of holes via degenerate statistics in the space charge region. The results reveal a large amount of majority carriers at the minority carrier extraction contact, assisted by additional ionic charge. The surface band bending related to accumulation gives an electrostatic contribution to the photovoltage in a manner governed by slow dynamics of cations at the electron-selective contact. The modeling of the interface allows us to describe the dynamics of the contact region dominated by surface charging and recombination. These phenomena also play an important role in operation conditions and current-voltage scans of the solar cell.

The excited states of the Criegee intermediate CH2OO are studied in molecular dynamics simulations using directly potentials from multi-reference perturbation theory (MR-PT2). The photoexcitation of the species is simulated, and trajectories are propagated in time on the excited state. Some of the photoexcitation events lead to direct fragmentation of the molecule, but other trajectories describe at least several vibrations in the excited state, that may terminate by relaxation to the ground electronic state. Limits on the role of non-adiabatic contributions to the process are estimated by two different simulations, one that forces surface-hopping at potential crossings, and another that ignores surface hopping altogether. The effect of non-adiabatic transitions is found to be small. Spectroscopic implications and consequences for the interpretation of experimental results are discussed.

This article reexamines the idea prevalent in existing historiography that Jews were accused of well poisoning before 1321. It argues that the historians who studied the origins of such accusations were misled by sources written in the early modern period to think that Jews were charged with well poisoning as early as the eleventh century. However, a careful analysis of the sources reveals that there is little reliable evidence that such cases happened before the fourteenth century, much less on a large scale. Thus, the conclusions of the article call for a new chronology of well-poisoning charges made against Jews, starting closer to the fourteenth century.

Aging is associated with progressive decline in cell function and with increased damage to macromolecular components. DNA damage, in the form of double-strand breaks (DSBs), increases with age and in turn, contributes to the aging process and age-related diseases. DNA strand breaks triggers a set of highly orchestrated signaling events known as the DNA damage response (DDR), which coordinates DNA repair. However, whether the accumulation of DNA damage with age is a result of decreased repair capacity, remains to be determined. In our study we showed that with age there is a decline in the resolution of foci containing γH2AX and pKAP-1 in diethylnitrosamine (DEN)-treated mouse livers, already evident at a remarkably early age of 6-months. Considerable age-dependent differences in global gene expression profiles in mice livers after exposure to DEN, further affirmed these age related differences in the response to DNA damage. Functional analysis identified p53 as the most overrepresented pathway that is specifically enhanced and prolonged in 6-month-old mice. Collectively, our results demonstrated an early decline in DNA damage repair that precedes 'old age', suggesting this may be a driving force contributing to the aging process rather than a phenotypic consequence of old age.

Exploitation of alternative water sources is expected to grow in the decades to come in water-stressed countries with fast population growth, especially in regions where a further decline of natural freshwater availability is expected due to climate change. Increasing utilization of non-freshwater usually leads to salinity build-up in fields and water sources as well as accumulation of various pollutants — both having a considerable impact on the suitability of non-freshwater for irrigation due to constraints associated with crop salinity tolerance and food safety regulations. We developed a linked Computable General Equilibrium (CGE) — farm-level model of a water economy with representation for multiple water types characterized by different qualities. We employ the model to assess the impact of water shortage on the Israeli economy, where steadily growing water scarcity leads to an increasing utilization of alternative water sources. We simulate water shortage scenarios based on the Long Term National Master Plan for The Water Economy developed by the Israeli Water Authority (IWA). The linked CGE — farm-level model provides a mechanism for estimating the Constant Elasticity of Substitution (CES) rates between different irrigation water types used in agriculture. This mechanism accounts for the effects of salinity on yields and takes into consideration food safety regulations for irrigating crops with treated wastewater. We demonstrate that, in contrast to previous studies, CES rates between different water types are not identical. The CES rates obtained in our study have relatively low values, which can be attributed to the constraints associated with crop salinity tolerance and food safety regulations. Our results reveal that water shortage can lead to a significant decline of Israel’s GDP, where a considerable part of the decline is attributed to the decrease in agricultural outputs. The magnitude of the impact depends on the underlying assumptions regarding future desalination capacity. To further study the effect of desalination, we run simulations under various desalination levels and examine its impact on the GDP. We also examine the extent to which the impact of water shortage is sensitive to CES rates between different irrigation water types.

Calcium phosphate (CaP) ceramics are used in orthopedics and dentistry due to their excellent osseointegration and biocompatibility. The electrodeposition of CaP on titanium alloy covered with self-assembled monolayers (SAMs) was studied with respect to the influence of chain length, end-group charge, and anchoring group. SAMs with end-groups similar to the functional groups on the side chains of collagen were selected. This study is divided to three parts: (1) studying the effects of SAMs on the titanium substrate, (2) studying the process of nucleation and growth of the CaP on specific SAMs, and (3) characterizing the CaP coatings using various surface anal. techniques. It was concluded that the nucleation and growth behavior of CaP changed in the presence of the SAMs. Different surface energies and crystallog. phases were assocd. with this change. Although the nucleation remained progressive, the growth changed from three-dimensional on bare surfaces to two-dimensional on SAMs-covered surfaces. Moreover, the deposition kinetics was slower on SAMs-covered surfaces, with phases contg. a higher Ca/P ratio. Examn. of the coating revealed that different SAMs lead to different surface morphologies of the coating while maintaining its degree of crystallinity. Yet, the phase content changes from hydroxyapatite and octacalcium phosphate (HAp + OCP) on the bare electrode to OCP only on the SAMs-covered electrode. These changes may have a substantial effect on the in vivo behavior by changing the coating’s soly. and surface morphol., thus affecting cell adhesion, proliferation, and differentiation processes. [on SciFinder(R)]

Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the brain and its decreased levels are associated with the development of obesity and neurodegeneration. Our aim was to test the effect of dietary fat, its timing and the circadian clock on the expression of BDNF and associated signaling pathways in mouse brain and liver. Bdnf mRNA oscillated robustly in brain and liver, but with a 12-h shift between the tissues. Brain and liver Bdnf mRNA showed a 12-h phase shift when fed ketogenic diet (KD) compared with high-fat diet (HFD) or low-fat diet (LFD). Brain or liver Bdnf mRNA did not show the typical phase advance usually seen under time-restricted feeding (RF). Clock knockdown in HT-4 hippocampal neurons led to 86% up-regulation of Bdnf mRNA, whereas it led to 60% down-regulation in AML-12 hepatocytes. Dietary fat in mice or cultured hepatocytes and hippocampal neurons led to increased Bdnf mRNA expression. At the protein level, HFD increased the ratio of the mature BDNF protein (mBDNF) to its precursor (proBDNF). In the liver, RF under LFD or HFD reduced the mBDNF/proBDNF ratio. In the brain, the two signaling pathways related to BDNF, mTOR and AMPK, showed reduced and increased levels, respectively, under timed HFD. In the liver, the reverse was achieved. In summary, Bdnf expression is mediated by the circadian clock and dietary fat. Although RF does not affect its expression phase, in the brain, when combined with high-fat diet, it leads to a unique metabolic state in which AMPK is activated, mTOR is down-regulated and the levels of mBDNF are high.

The number of immigrant students in Western Europe is growing steadily, but their social integration and educational achievements are still lagging behind. Nevertheless, there is still very little empirical evidence on which policies can effectively promote them. Thus, this article tests 2 main types of policies: targeted support and intercultural policies, and compares their effect on university graduation of 6 immigrant groups in 13 Western European countries. This research incorporates country- and origin-based variables as well as social and individual characteristics in cross-classified multilevel analyses. Data from the European Social Survey, the Migrant Integration Policy Index, the United Nations (UN) database and the World Bank database are integrated here. Findings show that intercultural policies have more positive effect on immigrant students than targeted policies. Furthermore, there is division between these six groups not only in their actual educational achievements, but also in the extent to which they are helped by education policies.