{An important property of hybrid layered perovskite is the possibility to reduceits dimensionality to provide wider band gap and better stability. In this work,2D perovskite of the structure (PEA)2(MA)n–1PbnBr3n+1 has been sensitized,where PEA is phenyl ethyl-ammonium, MA is methyl-ammonium, and usingonly bromide as the halide. The number of the perovskite layers has beenvaried (n) from n = 1 through n = ∞. Optical and physical characterizationverify the layered structure and the increase in the band gap. The photovoltaicperformance shows higher open circuit voltage (Voc) for the quasi 2D perovskite(i.e.
The critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved. Single-molecule fluorescence spectroscopy has been used to image and characterize single turnover sites at catalytic surfaces, but is restricted to reactions that generate highly fluorescing product molecules. Herein the chemical conversion of N-heterocyclic carbene molecules attached to catalytic particles is mapped using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 25 nanometres, which enabled particle regions that differ in reactivity to be distinguished. These observations demonstrate that, compared to the flat regions on top of the particles, the peripheries of the particles—which contain metal atoms with low coordination numbers—are more active in catalysing oxidation and reduction of chemically active groups in surface-anchored N-heterocyclic carbene molecules.
A key component in solar thermal energy conversion system is the light collector that is coated with an absorbing material. Optimal performance is accomplished by high absorptance and low emittance. The best collectors are fabricated by vacuum deposition processes, which are limited to small size and flat objects. Here, the formation and performance of a new three-layer solar selective coating, which is formed by a simple wet-deposition process is reported. The solar absorbing layer is based on carbon nanotubes, which are considered the most absorbing material. This layer is coated by a second layer of ITO, which functions as an IR reflecting layer, followed by an AlOOH anti-reflective layer. The resulting CNT/ITO/AlOOH coating exhibited the best-reported spectral selectivity by wet deposition process, with high absorptance of 0.941 +/- 0.004 and low emittance of 0.13 +/- 0.02 at room temperature. Furthermore, the multilayer sprayable coating is stable at elevated temperature for a prolong time and therefore, shows promise for application in large scale and on-site solar thermal facilities.
In this Letter, we systematically explore the influence of TiO2 thickness with nanometric variations over a range of 20-600 nm on the photovoltaic parameters (open-circuit voltage, short circuit current, fill-factor, and power conversion efficiency) of CH3NH3PbI3-based solar cells. We fabricate several sample libraries of 13 x 13 solar cells on large substrates with spatial variations in the thickness of the TiO2 layers while maintaining similar properties for the other layers. We show that the optimal thickness is similar to 50 nm for maximum performance; thinner layers typically resulted in short-circuited cells, whereas increasing the thickness led to a monotonic decrease in performance. Furthermore, by assuming a fixed bulk resistivity of TiO2, we were able to correlate the TiO2 thickness to the series and shunt resistances of the devices and model the variation in the photovoltaic parameters with thickness using the diode equation to gain quantitative insights.
We present a simple and effective high-throughput experimental platform for simultaneous and continuous monitoring of water relations in the soil-plant-atmosphere continuum of numerous plants under dynamic environmental conditions. This system provides a simultaneously measured, detailed physiological response profile for each plant in the array, over time periods ranging from a few minutes to the entire growing season, under normal, stress and recovery conditions and at any phenological stage. Three probes for each pot in the array and a specially designed algorithm enable detailed water-relations characterization of whole-plant transpiration, biomass gain, stomatal conductance and root flux. They also enable quantitative calculation of the whole plant water-use efficiency and relative water content at high resolution under dynamic soil and atmospheric conditions. The system has no moving parts and can fit into many growing environments. A screening of 65 introgression lines of a wild tomato species (Solanum pennellii) crossed with cultivated tomato (S. lycopersicum), using our system and conventional gas-exchange tools, confirmed the accuracy of the system as well as its diagnostic capabilities. The use of this high-throughput diagnostic screening method is discussed in light of the gaps in our understanding of the genetic regulation of whole-plant performance, particularly under abiotic stress.
We present a simple and effective high-throughput experimental platform for simultaneous and continuous monitoring of water relations in the soil-plant-atmosphere continuum of numerous plants under dynamic environmental conditions. This system provides a simultaneously measured, detailed physiological response profile for each plant in the array, over time periods ranging from a few minutes to the entire growing season, under normal, stress and recovery conditions and at any phenological stage. Three probes for each pot in the array and a specially designed algorithm enable detailed water-relations characterization of whole-plant transpiration, biomass gain, stomatal conductance and root flux. They also enable quantitative calculation of the whole plant water-use efficiency and relative water content at high resolution under dynamic soil and atmospheric conditions. The system has no moving parts and can fit into many growing environments. A screening of 65 introgression lines of a wild tomato species (Solanum pennellii) crossed with cultivated tomato (S. lycopersicum), using our system and conventional gas-exchange tools, confirmed the accuracy of the system as well as its diagnostic capabilities. The use of this high-throughput diagnostic screening method is discussed in light of the gaps in our understanding of the genetic regulation of whole-plant performance, particularly under abiotic stress.
Clinical studies suggest that key genetic factors involved in stress resilience are related to the innate immune system. In the brain, this system includes microglia cells, which play a major role in stress responsiveness. Consistently, mice with deletion of the CX3CR1 gene (CX3CR1(-/-) mice), which in the brain is expressed exclusively by microglia, exhibit resilience to chronic stress. Here, we compared the emotional, cognitive, neurogenic and microglial responses to chronic unpredictable stress (CUS) between CX3CR1(-/-) and wild type (WT) mice. This was followed by hippocampal whole transcriptome (RNA-seq) analysis. We found that following CUS exposure, WT mice displayed reduced sucrose preference, impaired novel object recognition memory, and reduced neurogenesis, whereas CX3CR1(-/-) mice were completely resistant to these effects of CUS. CX3CR1(-/-) mice were also resilient to the memory-suppressive effect of a short period of unpredictable stress. Microglial somas were larger in CX3CR1(-/-) than in WT, but in both genotypes CUS induced a similar decline in hippocampal microglial density and processes length. RNA sequencing and pathway analysis revealed basal strain differences, particularly reduced expression of interferon (IFN)-regulated and MHC class I gene transcripts in CX3CR1(-/-) mice. Furthermore, while CUS exposure similarly altered neuronal gene transcripts (e.g. Arc, Npas4) in both strains, transcripts downstream of hippocampal estrogen receptor signaling (particularly Igf2 and Igfbp2) were altered only in CX3CR1(-/-) mice. These findings indicate that emotional and cognitive stress resilience involves CX3CR1-dependent basal and stress-induced alterations in hippocampal transcription, implicating inhibition of CX3CR1 signaling as a novel approach for promoting stress resilience.
In this communication we argue that it is improbable that the main cause of death in sepsis is that, upon releaseof extracellular traps from neutrophils adhering to endothelial cells, highly cationic toxic histones uniquely causeendothelial dysregulation, organ failure and death. Activation of neutrophils is always accompanied by a plethora ofpro-inflammatory agents, which may act in synergy with histones to injure cells. Furthermore, many recent articleshave shown a steep rise of circulating histones in many clinical disorders unrelated to sepsis. We argue thereforethat histones do not act as unique alarmins with an outsized role, but are probably another marker of cell damage.
Cultural and communal boundaries of the Sephardic communities emerged via hybridization and from the assimilation of elements of diverse cultural origin, in which the formation of Judeo-Spanish played a key role in the imaginative processes of developing Sephardic identity, and its preservation as the “language-of-power” within the communities gave meaning to their further existence. This chapter deals with language contact with Portuguese, variation and change in Judeo-Spanish. The intensity of this contact varied according to place and time, and the high degree of overlap in linguistic structure, which allowed significant interlingual conflation, will become obvious through these three patterns.
Honey bee colonies require adequate pollen for maintenance and growth. Pollens vary in nutritional value, and a balanced diet is achieved by mixing pollens with complementary essential nutrients. We tested subjective evaluation of pollens by foragers in colonies deprived of one of two essential fatty acids (eFAs), alpha-linolenic acid (omega-3) or linoleic acid (omega-6). We used four pollens, two rich in omega-3 and two rich in omega-6. A colony in an observation hive was allowed to forage for 2–5 days on a single pollen source. The following day, we repeatedly presented one of three pollens: the same pollen that the bees had been collecting the previous days, a novel pollen that was similarly deficient in omega-3 or omega-6, and a novel pollen that complemented their eFA deficiency. We measured the rate of waggle dances, which reflects on the strength of recruitment effort, of foragers returning to the observation hive from each of the pollens. Dance rates did not differ between the four pollens, but they were the highest to the ``complementary'' pollen and the lowest to the ``same'' pollen. Furthermore, this effect was greater for pollen combinations with greater eFA disparity between the same and the complementary pollens. Our findings support the ability of bees to balance colony eFA intake. Conditioning of the proboscis extension response (PER) tests showed that pollen foragers discriminated well between the four pollen odors, but the mechanisms by which bees assess pollen eFA composition remain to be elucidated. Differential dancing would recruit foragers to pollens that balance colony nutritional needs.
Paul Andreas Walker, Alesini, PD , Alexandrova, AS , Anania, Maria Pia, Andreev, NE , Andriyash, I , Aschikhin, A , Assmann, RW , Audet, T , Bacci, A , ו others, . 2017. “Horizon 2020 Eupraxia Design Study”. בתוך Journal Of Physics: Conference Series, 874:Pp. 012029. IOP Publishing.
Escherichia coli is transformed from a commensal organism into a pathogen by acquisition of genetic elements called pathogenicity islands (PAIs). Katsowich et al. investigated how the PAI virulence genes of enteropathogenic E. coli (EPEC) respond when the bacterium attaches to a host gut cell. EPEC first sticks to the host by means of pili and then uses a PAI-encoded type 3 secretion system (T3SS) to inject multiple effectors into the host cell. But not all virulence mediators are injected. For example, CesT, a bacterial chaperone, delivers virulence effectors into the T3SS apparatus. Then, within the bacterial cytoplasm, it interacts with a gene repressor called CsrA, which reprograms bacterial gene expression to help the bacteria to adapt to epithelial cell–associated life.Science, this issue p. 735The mechanisms by which pathogens sense the host and respond by remodeling gene expression are poorly understood. Enteropathogenic Escherichia coli (EPEC), the cause of severe intestinal infection, employs a type III secretion system (T3SS) to inject effector proteins into intestinal epithelial cells. These effectors subvert host cell processes to promote bacterial colonization. We show that the T3SS also functions to sense the host cell and to trigger in response posttranscriptional remodeling of gene expression in the bacteria. We further show that upon effector injection, the effector-bound chaperone (CesT), which remains in the EPEC cytoplasm, antagonizes the posttranscriptional regulator CsrA. The CesT-CsrA interaction provokes reprogramming of expression of virulence and metabolic genes. This regulation is likely required for the pathogen’s adaptation to life on the epithelium surface.
The composition and diversity of bacteria forming the microbiome of parasitic organisms have implications for differential host pathogenicity and host-parasite co-evolutionary interactions. The microbiome of pathogens can therefore have consequences that are relevant for managing disease prevalence and impact on affected hosts. Here, we investigate the microbiome of an invasive parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, where it poses extinction threat to Darwin's finches and other land birds. Larvae infest nests of Darwin's finches and consume blood and tissue of developing nestlings, and have severe mortality impacts. Using 16s rRNA sequencing data, we characterize the bacterial microbiota associated with P. downsi adults and larvae sourced from four finch host species, inhabiting two islands and representing two ecologically distinct groups. We show that larval and adult microbiomes are dominated by the phyla Proteobacteria and Firmicutes, which significantly differ between life stages in their distributions. Additionally, bacterial community structure significantly differed between larvae retrieved from strictly insectivorous warbler finches (Certhidea olivacea) and those parasitizing hosts with broader dietary preferences (ground and tree finches, Geospiza and Camarhynchus spp., respectively). Finally, we found no spatial effects on the larval microbiome, as larvae feeding on the same host (ground finches) harboured similar microbiomes across islands. Our results suggest that the microbiome of P. downsi changes during its development, according to dietary composition or nutritional needs, and is significantly affected by host-related factors during the larval stage. Unravelling the ecological significance of bacteria for this parasite will contribute to the development of novel, effective control strategies.
The composition and diversity of bacteria forming the microbiome of parasitic organisms have implications for differential host pathogenicity and host-parasite co-evolutionary interactions. The microbiome of pathogens can therefore have consequences that are relevant for managing disease prevalence and impact on affected hosts. Here, we investigate the microbiome of an invasive parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, where it poses extinction threat to Darwin's finches and other land birds. Larvae infest nests of Darwin's finches and consume blood and tissue of developing nestlings, and have severe mortality impacts. Using 16s rRNA sequencing data, we characterize the bacterial microbiota associated with P. downsi adults and larvae sourced from four finch host species, inhabiting two islands and representing two ecologically distinct groups. We show that larval and adult microbiomes are dominated by the phyla Proteobacteria and Firmicutes, which significantly differ between life stages in their distributions. Additionally, bacterial community structure significantly differed between larvae retrieved from strictly insectivorous warbler finches (Certhidea olivacea) and those parasitizing hosts with broader dietary preferences (ground and tree finches, Geospiza and Camarhynchus spp., respectively). Finally, we found no spatial effects on the larval microbiome, as larvae feeding on the same host (ground finches) harboured similar microbiomes across islands. Our results suggest that the microbiome of P. downsi changes during its development, according to dietary composition or nutritional needs, and is significantly affected by host-related factors during the larval stage. Unravelling the ecological significance of bacteria for this parasite will contribute to the development of novel, effective control strategies.
