Identification of lead vacancy defects in lead halide perovskites.

Perovskite photovoltaics advance rapidly, but questions remain regarding point defects: while experiments have detected the presence of electrically active defects no experimentally confirmed microscopic identifications have been reported. Here we identify lead monovacancy (V) defects in MAPbI (MA = CHNH) using positron annihilation lifetime spectroscopy with the aid of density functional theory. Experiments on thin film and single crystal samples all exhibited dominant positron trapping to lead vacancy defects, and a minimum defect density of ~3 × 10 cm was determined.

Porosimetry for Thin Films of Metal-Organic Frameworks: A Comparison of Positron Annihilation Lifetime Spectroscopy and Adsorption-Based Methods.

Thin films of crystalline and porous metal-organic frameworks (MOFs) have great potential in membranes, sensors, and microelectronic chips. While the morphology and crystallinity of MOF films can be evaluated using widely available techniques, characterizing their pore size, pore volume, and specific surface area is challenging due to the low amount of material and substrate effects. Positron annihilation lifetime spectroscopy (PALS) is introduced as a powerful method to obtain pore size information and depth profiling in MOF films.

Non-steady diffusion and adsorption of organic micropollutants in ion-exchange membranes: effect of the membrane thickness.

There is no efficient wastewater treatment solution for removing organic micropollutants (OMPs), which, therefore, are continuously introduced to the Earth's surface waters. This creates a severe risk to aquatic ecosystems and human health. In emerging water treatment processes based on ion-exchange membranes (IEM), transport of OMPs through membranes remains unknown.

Transport of organic solutes in ion-exchange membranes: Mechanisms and influence of solvent ionic composition.

Ion-exchange membrane (IEM)-based processes are used in the industry or in the drinking water production to achieve selective separation. The transport mechanisms of organic solutes/micropollutants (i.e.

Template-Mediated Control over Polymorphism in the Vapor-Assisted Formation of Zeolitic Imidazolate Framework Powders and Films.

The landscape of possible polymorphs for some metal-organic frameworks (MOFs) can pose a challenge for controlling the outcome of their syntheses. Demonstrated here is the use of a template to control in the vapor-assisted formation of zeolitic imidazolate framework (ZIF) powders and thin films. Introducing a small amount of either ethanol or dimethylformamide vapor during the reaction between ZnO and 4,5-dichloroimidazole vapor results in the formation of the porous ZIF-71 phase, whereas other conditions lead to the formation of the dense ZIF-72 phase or amorphous materials.

Tuning Selectivities in Gas Separation Membranes Based on Polymer-Grafted Nanoparticles.

Polymer membranes are critical to many sustainability applications that require the size-based separation of gas mixtures. Despite their ubiquity, there is a continuing need to selectively affect the transport of different mixture components while enhancing mechanical strength and hindering aging. Polymer-grafted nanoparticles (GNPs) have recently been explored in the context of gas separations.

Aqueous Flow Reactor and Vapour-Assisted Synthesis of Aluminium Dicarboxylate Metal-Organic Frameworks with Tuneable Water Sorption Properties.

Energy-efficient indoors temperature and humidity control can be realised by using the reversible adsorption and desorption of water in porous materials. Stable microporous aluminium-based metal-organic frameworks (MOFs) present promising water sorption properties for this goal. The development of synthesis routes that make use of available and affordable building blocks and avoid the use of organic solvents is crucial to advance this field.

Morphology of Thin Film Composite Membranes Explored by Small-Angle Neutron Scattering and Positron-Annihilation Lifetime Spectroscopy.

The morphology of thin film composite (TFC) membranes used in reverse osmosis (RO) and nanofiltration (NF) water treatment was explored with small-angle neutron scattering (SANS) and positron-annihilation lifetime spectroscopy (PALS). The combination of both methods allowed the characterization of the bulk porous structure from a few Å to µm in radius. PALS shows pores of 4.

Confinement of Positrons Exceeding 1 s in a Supported Magnetic Dipole Trap.

An ensemble of low-energy positrons injected into a supported magnetic dipole trap can remain trapped for more than a second. Trapping experiments with and without a positive magnet bias yield confinement times up to τ_{A}=(1.5±0.

Lossless Positron Injection into a Magnetic Dipole Trap.

The high-efficiency injection of a low-energy positron beam into the confinement volume of a magnetic dipole has been demonstrated experimentally. This was accomplished by tailoring the three-dimensional guiding-center drift orbits of positrons via optimization of electrostatic potentials applied to electrodes at the edge of the trap, thereby producing localized and essentially lossless cross-field particle transport by means of the E×B drift. The experimental findings are reproduced and elucidated by numerical simulations, enabling a comprehensive understanding of the process.

Reversible Optical Writing and Data Storage in an Anthracene-Loaded Metal-Organic Framework.

Metal-organic frameworks (MOFs) enable the design of host-guest systems with specific properties. In this work, we show how the confinement of anthracene in a well-chosen MOF host leads to reversible yellow-to-purple photoswitching of the fluorescence emission. This behavior has not been observed before for anthracene, either in pure form or adsorbed in other porous hosts.

Crosslinked PVA/SSA proton exchange membranes: correlation between physiochemical properties and free volume determined by positron annihilation spectroscopy.

Two processes for crosslinking polyvinyl alcohol (PVA) with sulfosuccinic acid (SSA) and thermal crosslinking were used to fabricate a proton exchange membrane (PEM). Such PEMs are used in different fields involving fuel cell applications. The crosslinking reaction between PVA and SSA was confirmed using Fourier-transform infrared (FTIR) spectroscopy.

Nature of the Positron State in CdSe Quantum Dots.

Previous studies have shown that positron-annihilation spectroscopy is a highly sensitive probe of the electronic structure and surface composition of ligand-capped semiconductor quantum dots (QDs) embedded in thin films. The nature of the associated positron state, however, whether the positron is confined inside the QDs or localized at their surfaces, has so far remained unresolved. Our positron-annihilation lifetime spectroscopy studies of CdSe QDs reveal the presence of a strong lifetime component in the narrow range of 358-371 ps, indicating abundant trapping and annihilation of positrons at the surfaces of the QDs.

Impact of real-time elastography on magnetic resonance imaging/ultrasound fusion guided biopsy in patients with prior negative prostate biopsies.

Purpose: The fusion of multiparametric resonance imaging and ultrasound has been proven capable of detecting prostate cancer in different biopsy settings. The addition of real-time elastography promises to increase the precision of the outcome of targeted biopsies. We investigated whether real-time elastography improves magnetic resonance imaging/transrectal ultrasound fusion targeted biopsy in patients after previous negative biopsies.

A qualitative study of barriers to the implementation of a rheumatoid arthritis guideline among generalist and specialist physical therapists.

Background: Although the increasing complexity and expansion of the body of knowledge in physical therapy have led to specialized practice areas to provide better patient care, the impact of specialization on guideline implementation has been scarcely studied. Objectives The objective of this study was to identify the similarities and differences in barriers to the implementation of a Dutch rheumatoid arthritis (RA) guideline by generalist and specialist physical therapists. Design This observational study consisted of 4 focus group interviews in which 24 physical therapists (13 generalist and 11 specialist physical therapists) participated.

Monitoring the coupling of the lithotripter therapy head with skin during routine shock wave lithotripsy with a surveillance camera.

Purpose: With lithotripters today the shock waves are typically transmitted into the body via water filled bellows using coupling gel to make contact with the skin. Usually the coupling zone is not visible to the operator. We investigated coupling quality during routine clinical shock wave lithotripsy and the associated effect on shock wave disintegration efficiency.

Predictive factors for urinary retention following kidney transplantation in male patients.

Objective: Urinary retention frequently occurs in patients after kidney transplantation. This study aimed to identify predictive factors for urinary retention requiring transurethral resection of the prostate (TURP) following kidney transplantation.

Material And Methods: Seventy male patients (median age 56 years, range 37-73 years) who underwent kidney transplantation between 1995 and 2006, and experienced urinary retention and consecutively required TURP, were studied retrospectively.

[Drug therapy options for oligoasthenoteratozoospermia syndrome].

Medical treatment of oligoasthenoteratozoospermia (OAT) syndrome includes many different treatment concepts. The targeted causes in the treatment of OAT syndrome are either hormonal, as for example hypothalamic, pituary, or, seldom, hyperprolactinemic disturbances, or acute or chronic urogenital infections, as well as ejaculatory disorders. Often no pathogenic reason for OAT syndrome can be found and targeted.

[Laboratory work-up of testosterone].

Measuring testosterone concentration is a central component of routine andrological diagnostics. To avoid complicated and often imprecise direct measurement of bioavailable testosterone, calculation by SHBG and albumin concentration is possible. When interpreting a measured testosterone concentration, numerous influencing factors have to be kept in mind.