Interlayer excitons in MoSe2/2D perovskite hybrid heterostructures - the interplay between charge and energy transfer

van der Waals crystals have opened a new and exciting chapter in heterostructure research, removing the lattice matching constraint characteristics of epitaxial semiconductors. They provide unprecedented flexibility for heterostructure design. Combining two-dimensional (2D) perovskites with other 2D materials, in particular transition metal dichalcogenides (TMDs), has recently emerged as an intriguing way to design hybrid opto-electronic devices. However, the excitation transfer mechanism between the layers (charge or energy transfer) remains to be elucidated. Here, we investigate PEA₂PbI₄/MoSe₂ and (BA)₂PbI₄/MoSe₂ heterostructures by combining optical spectroscopy and density functional theory (DFT) calculations. We show that band alignment facilitates charge transfer. Namely, holes are transferred from TMDs to 2D perovskites, while the electron transfer is blocked, resulting in the formation of interlayer excitons. Moreover, we show that the energy transfer mechanism can be turned on by an appropriate alignment of the excitonic states, providing a rule of thumb for the deterministic control of the excitation transfer mechanism in TMD/2D-perovskite heterostructures.

Nonradiative Energy Transfer and Selective Charge Transfer in a WS2/(PEA)2PbI4 Heterostructure

van der Waals heterostructures are currently the focus of intense investigation; this is essentially due to the unprecedented flexibility offered by the total relaxation of lattice matching requirements and their new and exotic properties compared to the individual layers. Here, we investigate the hybrid transition-metal dichalcogenide/2D perovskite heterostructure WS₂/(PEA)₂PbI₄ (where PEA stands for phenylethylammonium). We present the first density functional theory (DFT) calculations of a heterostructure ensemble, which reveal a novel band alignment, where direct electron transfer is blocked by the organic spacer of the 2D perovskite. In contrast, the valence band forms a cascade from WS₂ through the PEA to the PbI₄ layer allowing hole transfer. These predictions are supported by optical spectroscopy studies, which provide compelling evidence for both charge transfer and nonradiative transfer of the excitation (energy transfer) between the layers. Our results show that TMD/2D perovskite (where TMD stands for transition-metal dichalcogenides) heterostructures provide a flexible and convenient way to engineer the band alignment.

Assessment of certain ionic liquids for separation of binary mixtures based on gamma infinity data measurements

Limiting activity coefficients for 64 solutes in [BzMIM][NTf₂] and [BzMIM][DCA], the gas–liquid partition coefficients, K_L, thermodynamic functions and selectivity for hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene separation were presented.

Human red blood cells' physiological water exchange with the plasma

In the present paper, fundamental issues related to the mechanisms of human red blood cells' physiological water exchange with the plasma (for the stationary conditions) have been discussed. It has been demonstrated, on the basis of mechanistic transport equations for membrane transport that red blood cells are capable of exchanging considerable amounts of water with the plasma. Water absorption is osmosis-driven, and its removal occurs according to the hydromechanics principle, i.e. is driven by the turgor pressure of red blood cells. This newly-acquired knowledge of these issues may appear highly useful for clinical diagnosis of blood diseases and blood circulation failures.

[Vesicoureteral refluxes in children during the first two years of life]

Ninety-six children with vesicoureteral reflux (VUR) diagnosed by age 2 were studied. The most common indication for radiological visualization of the urinary tract was a urinary tract infection (UTI). Among 143 cases of VUR, 51% were unilateral and 49% were bilateral. Other urinary tract abnormalities coexisted with VUR in 14.6% of children. Abnormal USG result was found in 24% of children, including only 13.4% with VUR and other urinary tract abnormalities. Conservative treatment was chosen in 126 (88%) cases of VUR in 87.5% of children. Follow-up voiding cystourethrography was performed in 60.7% of children. Conservative treatment was successful in 68.6% of children. VUR disappeared in 70.9% of cases after mean follow-up of 13.7 months (including 76.2% cases of VUR grade II, 54.5% cases of VUR grade III and 50% cases of VUR grade I). Recurrent UTI and lack of improvement after conservative treatment were indications for surgical treatment in 9.8% of children. Recurrent UTI were observed in 15.6% of children (including 16.7% among those treated conservatively and 8.3% among those treated surgically) and their course was febrile in most cases.

Indoor radon concentrations in Poland as determined in short-term (two-day) measurements

The aim of the present work was to obtain a pattern of 222Rn concentration distributions in typical buildings in Poland. In the investigations, the environmental passive detectors of the PICO-RAD type were used. The study encompassed buildings that were typical for Poland. The distribution of airborne 222Rn concentrations indoors is of a log-normal type. A total 1171 detectors were measured. Measurements were made in 319 basements, the remaining 852 measurements were carried out in the inhabited part of the houses. The radon concentrations in the basements in Bq x m(-3) ranged from 6 to 1300 with the arithmetic mean AM = 60, geometric mean GM = 30 and median M = 28, whereas those in the inhabited parts of the house (above the ground level) were: AM = 25, GM = 17 and M = 16 with the highest record value of 420.

Antioxidative activity of rosemary extract in lipid fraction of minced meat balls during storage in a freezer

The influence of ethanol rosemary extract on lipid fraction of minced meat balls during storage in the freezer was studied. The quality of stored products was evaluated sensorically by the scale method and profiling of taste and aroma. Oxidative changes were investigated on the base of the changes in malonaldehyde content. It was observed that the addition of rosemary extract delayed the oxidation of lipid fraction of products. The antioxidative effect was related to the concentration of this extract in the product. The sensory changes and their intensity in products during storage depended on the amount of the extract added and the time of storage. The addition of the extract delayed the appearance of rancid taste in products.

[The measurement of radon in kindergarten and infant nursery buildings in East-North Poland]

The measurements of radon concentration in 58 buildings of day nursery schools and kindergartens were performed in the six province of the East North Poland. The measurements of indoor radon were performed by means of a charcoal canister (Pico-Rad). The concentration ranged from 4.5 to 320 Bq/m3 and have arthimetic average 24.5 Bq/m3, geometric average 15.7 Bq/m3, median 15 Bq/m3. The highest average values were observed in Suwałki Province and Olsztyn Province. The results of all these measurements do not exceeded the limit of the Polish law.