"Electronic coupling and hence hybridization of atoms serves as the bas is for the rich properties for the endless library of naturally occurring molecules. Colloidal quantum dots (CQDs) manifesting quantum strong confinement possess atomic-like characteristics with s and p electronic levels, which popularized the notion of CQDs as artificial atoms. Continuing this analogy, when two atoms are close enough to form a molecule so that their orbitals start overlapping, the orbitals energies start to split into bonding and antibonding states made out of hybridized orbitals. The same concept is also applicable for two fused core–shell nanocrystals in close proximity. Their band edge states, which dictate the emitted photon energy, start to hybridize, changing their electronic and optical properties. Thus, an exciting direction of “artificial molecules” emerges, leading to a multitude of possibilities for creating a library of new hybrid nanostructures with novel optoelectronic properties with relevance toward diverse applications including quantum technologies.
The controlled separation and the barrier height between two adjacent quantum dots are key variables for dictating the magnitude of the coupling energy of the confined wave functions. In the past, coupled double quantum dot architectures prepared by molecular beam epitaxy revealed a coupling energy of few millielectron volts, which limits the applications to mostly cryogenic operation. The realization of artificial quantum molecules with sufficient coupling energy detectable at room temperature calls for the use of colloidal semiconductor nanocrystal building blocks. Moreover, the tunable surface chemistry widely opens the predesigned attachment strategies as well as the solution processing ability of the prepared artificial molecules, making the colloidal nanocrystals as an ideal candidate for this purpose. Despite several approaches that demonstrated enabling of the coupled structures, a general and reproducible method applicable to a broad range of colloidal quantum materials is needed for systematic tailoring of the coupling strength based on a dictated barrier.
This Account addresses the development of nanocrystal chemistry to create coupled colloidal quantum dot molecules and to study the controlled electronic coupling and their emergent properties. The simplest nanocrystal molecule, a homodimer formed from two core/shell nanocrystal monomers, in analogy to homonuclear diatomic molecules, serves as a model system. The shell material of the two CQDs is structurally fused, resulting in a continuous crystal. This lowers the potential energy barrier, enabling the hybridization of the electronic wave functions. The direct manifestation of the hybridization reflects on the band edge transition shifting toward lower energy and is clearly resolved at room temperature. The hybridization energy within the single homodimer molecule is strongly correlated with the extent of structural continuity, the delocalization of the exciton wave function, and the barrier thickness as calculated numerically. The hybridization impacts the emitted photon statistics manifesting faster radiative decay rate, photon bunching effect, and modified Auger recombination pathway compared to the monomer artificial atoms. Future perspectives for the nanocrystals chemistry paradigm are also highlighted."
Multi-walled carbon nanotubes (MWCNTs) are promising materials for chemical gas sensing because of their high electrical and mechanical properties and significant sensitivity to changes in the local environment. However, high-content MWCNT films suffer from the low tunability of the electrical resistance, which is crucial for high chemoresistive sensing performance. This study reports the conjugation of MWCNTs and oligomers of polyaniline (PANI) doped with Ag(+) or Cu(2+) incorporated into a PVC/polyacrylate. MWCNTs were sonicated in n-methyl pyrrolidine (NMP), and PANI was conjugated via a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and an N-hydroxysuccinimide (EDC/NHS) process. MWCNT/PANI Ag(+) or Cu(2+) conjugates were doped to form a coordinate bond. The doped conjugates were successfully incorporated into the PVC/polyacrylate. These MWCNT/PANI conjugates doped were exposed to different concentrations of ethylene gas to examine their feasibility for ethylene detection.
Multi-walled carbon nanotubes (MWCNTs) are promising materials for chemical gas sensing because of their high electrical and mechanical properties and significant sensitivity to changes in the local environment. However, high-content MWCNT films suffer from the low tunability of the electrical resistance, which is crucial for high chemoresistive sensing performance. This study reports the conjugation of MWCNTs and oligomers of polyaniline (PANI) doped with Ag+ or Cu2+ incorporated into a PVC/polyacrylate. MWCNTs were sonicated in n-methyl pyrro-lidine (NMP), and PANI was conjugated via a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and an N-hydroxysuccinimide (EDC/NHS) process. MWCNT/PANI Ag+ or Cu2+ conjugates were doped to form a coordinate bond. The doped conjugates were successfully incorporated into the PVC/polyacrylate. These MWCNT/PANI conjugates doped were exposed to different concentrations of ethylene gas to examine their feasibility for ethylene detection.
ABSTRACTBackground: University and college students are not usually identified as a population at risk during the COVID-19 pandemic. Yet, there is growing evidence of their specific distress associated with facing multiple abrupt changes and the need for rapid adaptation to a variety of academic, social, and financial challenges. The extent of their exposure to COVID-19 media and the associated media-related stress may further impair students? perceived coping.Objective: This study assessed COVID-19-related functional difficulties and perceived coping among higher education students in Israel and explored the moderating role played by media coverage of the pandemic in inducing stress and exacerbating COVID-19-related difficulties in perceived coping among students.Method: Data was collected from 7,446 students from seven academic centres in Israel through online questionnaires about four to six weeks after the outbreak of the pandemic in Israel.Results: The findings showed positive associations between COVID-19-related difficulties, media exposure, media-related stress, and decreased levels of perceived coping with the pandemic. Moreover, media-related stress (but not the level of media exposure) moderated the relationship between COVID-19-related difficulties and perceived coping: the associations were significantly stronger for students reporting high media-related stress in comparison to individuals reporting low media-related stress.Conclusions: These results highlight the specific role of media-related stress and the need to distinguish this risk factor from the global impact of exposure to media coverage. The need for self-monitoring of the subjective level of stress associated with media exposure should be part of the psychoeducation efforts provided by public health authorities for promoting self-care during the COVID-19 pandemic.
Obesity is one of the foremost risk factors in coronavirus infection resulting in severe illness and mortality as the pandemic progresses. Obesity is a well-known predisposed chronic inflammatory condition. The dynamics of obesity and its impacts on immunity may change the disease severity of pneumonia, especially in acute respiratory distress syndrome, a primary cause of death from SARS-CoV-2 infection. The adipocytes of adipose tissue secret leptin in proportion to individuals' body fat mass. An increase in circulating plasma leptin is a typical characteristic of obesity and correlates with a leptin-resistant state. Leptin is considered a pleiotropic molecule regulating appetite and immunity. In immunity, leptin functions as a cytokine and coordinates the host's innate and adaptive responses by promoting the Th1 type of immune response. Leptin induced the proliferation and functions of antigen-presenting cells, monocytes, and T helper cells, subsequently influencing the pro-inflammatory cytokine secretion by these cells, such as TNF-alpha, IL-2, or IL-6. Leptin scarcity or resistance is linked with dysregulation of cytokine secretion leading to autoimmune disorders, inflammatory responses, and increased susceptibility towards infectious diseases. Therefore, leptin activity by leptin long-lasting super active antagonist's dysregulation in patients with obesity might contribute to high mortality rates in these patients during SARS-CoV-2 infection. This review systematically discusses the interplay mechanism between leptin and inflammatory cytokines and their contribution to the fatal outcomes in COVID-19 patients with obesity.
Minority groups are especially vulnerable to the negative psychological and economic consequences of the COVID-19 pandemic. This study focused on one prominent minority group in Israel: ultra-Orthodox Jews. It examined the rate of exposure to COVID-19, adherence to COVID-19 mitigation guidelines, difficulties with adherence to COVID-19 guidelines, COVID-related concerns, financial hardships, the need for help, and microaggression during the first wave of the pandemic (April–May 2020). It then examined multivariate prediction of COVID-related concerns, the need for help, and microaggression. The sample comprised 252 respondents, with 67% female and a mean age of 32.85 (SD = 10.63). Results showed that 78.8% of the participants knew at least one person who had tested positive for COVID-19, and 31.4% knew at least one person who had passed away from COVID-19. Only 59.7% of the participants reported high adherence to social distancing guidelines. Perceived microaggression was predicted by the difficulties with adherence to COVID-19 guidelines, the level of stress associated with exposure to the media, and financial hardships. The study’s implications point to the centrality of perceived microaggression and the necessity of adopting culturally sensitive approaches to engage minorities in public efforts to fight the spread of viruses.
Minority groups are especially vulnerable to the negative psychological and economic consequences of the COVID-19 pandemic. This study focused on one prominent minority group in Israel: ultra-Orthodox Jews. It examined the rate of exposure to COVID-19, adherence to COVID-19 mitigation guidelines, difficulties with adherence to COVID-19 guidelines, COVID-related concerns, financial hardships, the need for help, and microaggression during the first wave of the pandemic (April–May 2020). It then examined multivariate prediction of COVID-related concerns, the need for help, and microaggression. The sample comprised 252 respondents, with 67% female and a mean age of 32.85 (SD = 10.63). Results showed that 78.8% of the participants knew at least one person who had tested positive for COVID-19, and 31.4% knew at least one person who had passed away from COVID-19. Only 59.7% of the participants reported high adherence to social distancing guidelines. Perceived microaggression was predicted by the difficulties with adherence to COVID-19 guidelines, the level of stress associated with exposure to the media, and financial hardships. The study’s implications point to the centrality of perceived microaggression and the necessity of adopting culturally sensitive approaches to engage minorities in public efforts to fight the spread of viruses.
The COVID-19 pandemic has created a sense of threat, and stress that has surged globally at an alarming pace. University students were confronted with new challenges. This study examined university students’ functional difficulties and concerns during COVID-19 pandemic in two countries: Israel and Ukraine. Additionally, it examined the similarities and differences in prediction of COVID-related concerns in both countries. Two large samples of university students were drawn from both countries. Results showed that students’ main functional difficulties in both countries were: worries about their family health status and their learning assignments. In both countries, COVID-related functional difficulties and stress associated with exposure to the media added a significant amount of the explained variance of COVID-related concerns after controlling for background variables. In conclusion—while the level of exposure and difficulties may differ by country and context, their associations with students’ concerns seem robust. Additionally, repeated exposure to media coverage about a community threat can lead to increased anxiety.
Mass shootings have a strong impact on public discourse and perception, affecting more than their direct victims. We use data on charitable contributions and criminal activity in the U.S. over the last decade to identify and quantify the effect of mass shootings on prosocial and antisocial behavior. We find that the effect of mass shootings on prosocial behavior, measured primarily by monetary contributions, is positive and statistically significant. However, the directly affected localities react to mass shootings differently than their neighboring communities, decreasing their charitable contributions. Additionally, we are unable to find a statistically significant effect of mass shootings on antisocial behavior, as measured by various crime rates. Furthermore, we show that mass shootings are different than any other type of criminal behavior, including all other violent offenses, in terms of its effect on prosocial behavior.
This paper studies whether crony governance affects the logic behind governments’ targeting of violence, and how the deployment of violence allows politically connected firms to benefit from crony governance. We address these issues in the context of the Argentine military junta that took power on March 24, 1976. Specifically, we examine the logic driving the choice of firm level union representatives who were subjected to violence following the coup. Using an original dataset assembled and digitized by us, we find that political, business and social connections to the regime are associated with an increase of 2 to 3 times in the number of firm level union representatives arrested and/or disappeared. This is the case even after controlling for a battery of firms’ characteristics that capture alternative explanations for the targeting of violence. The effect is particularly pronounced in privately owned (as opposed to state-owned) firms, suggesting that the correlation is driven by cronyism for financial gain rather than ideology or information transmission. We also show that connected firms benefited from violence against union representatives by subsequently having less strikes and a higher market valuation. Our findings highlight the pervasiveness of ties to the government, even in cases where one of the main stated goals of the regime is to curb cronyism.
, when two atoms are close enough to form a molecule so that their orbitals start overlapping, the orbitals energies start to split into bonding and antibonding states made out of hybridized orbitals. The same concept is also applicable for two fused core–shell nanocrystals in close proximity. Their band edge states, which dictate the emitted photon energy, start to hybridize, changing their electronic and optical properties. Thus, an exciting direction of “artificial molecules” emerges, leading to a multitude of possibilities for creating a library of new hybrid nanostructures with novel optoelectronic properties with relevance toward diverse applications including quantum technologies.