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Purpose The white matter hyperintensity penumbra (WMH-P) is the subtly changed normal-appearing white matter (NAWM) that surrounds white matter hyperintensities (WMHs). The goal of this study was to define WMH-P in cerebral small vessel disease (CSVD) by arterial spin labeling (ASL) and diffusion tensor imaging (DTI)/diffusion kurtosis imaging (DKI). Materials and methods We prospectively analyzed 42 patients with CSVD. To determine the range of cerebral blood flow (CBF) and DTI/DKI penumbras around white matter hyperintensities, we generated NAWM layer masks from periventricular WMHs (PVWMHs) and deep WMHs (DWMHs). Mean values of CBF, fractional anisotropy, mean diffusivity, axial diffusivity, radial diffusivity, mean kurtosis, axial kurtosis, and radial kurtosis within the WMHs and their corresponding NAWM layer masks were analyzed. Paired sample t tests were used for analysis, and differences were considered statistically significant if the associated p value was ≤ 0.05. Results For DWMHs, the CBF penumbras were 13 mm, and the DTI/DKI penumbras were 8 mm. For PVWMHs, the CBF penumbras were 14 mm, and the DTI/DKI penumbras were 14 mm. Conclusions Our findings revealed that DTI/DKI and ASL can show structural and blood flow changes in brain tissue surrounding WMHs. In DWMHs, the blood flow penumbra was larger than the structural penumbra, while in PVWMHs, the blood flow penumbra was almost the same as the structural penumbra.

The optical properties and stability of metal halide perovskites can be improved by reducing their dimensionality. Because defects at the perovskite film grain body and boundaries cause significant energetic losses by nonradiative recombination, perovskite films with manageable crystal size and macroscopic grains are essential to improve the photovoltaic properties. Through theoretical calculation models and experiments, we show that the carboxyl group of 4-ammonium butyric acid-based cation (4-ABA

Defects at the interface and grain boundaries of perovskite solar cells (PSCs) will result in severe non-radiative recombination and open-circuit voltage (Voc) loss. Herein, we reported a zwitterionic ionic liquid imidazolium tetrafluoroborate (IMBF

Low dimensional interface passivation has been proved to be an efficient method to lessen the nonradiative recombination loss in perovskite solar cells. To overcome the limitation of Phenethylammonium (PEA+) for carrier transport and water molecule intrusion, we developed a modification strategy by functioning the typical PEA+ with the 4-methoxy to optimize the interface defects and carrier transport performance, thus maximizing the synchronous improvement of device efficiency and stability. Our results indicate that the 2 mg ml−1 4-methoxy-phenethylammonium (MeO-PEA+) modified device could achieve a best power conversion efficiency of 19.64% with improved shelf-life stability in ambient conditions. The new passivation molecule of MeO-PEA+ could possess the capability of defect passivation, carrier transfer, and moisture blocking, demonstrating that rationally designed organic components for interface passivation could help to achieve efficient and stable PSCs.

The trap-assisted nonradiative recombination at grain surface and grain boundary (GB) of perovskite films impede the further improvement of power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In addition, the poor moisture stability of perovskite films hinders the commercial application of PSCs. Herein, we report a multifunctional GB modification strategy where the wide-bandgap hydrophobic PbSO4 modification layer is in situ formed at the GBs of perovskite films through the reaction between methylamine sulfate and PbI2. It is revealed that multiple functions are achieved after the formation of PbSO4 modification layer, including crystallization improvement, defect passivation, and hydrophobicity improvement. As a result, the PbSO4 modified device exhibits a PCE enhancement from 19.53% to 21.90% as compared to the control device. Moreover, up to 71% of its initial PCE is maintained for the unencapsulated PbSO4 modified device after aging under a relative humidity of 80 ± 5% for 250 h. This work proposes an effective multifunctional approach to modify the GBs of perovskite films for the purpose of simultaneous increasement of PCE and stability.

We here demonstrate a facile one-step synthesis of RGO–Ni hybrid materials, where Ni2+ ions and GO are simultaneously reduced by γ-irradiation. RGO–Ni, with Ni nanoparticles well dispersed on the RGO surface, shows a more enhanced EM absorption ability than the individuals.

Electron beam irradiation method was successfully applied to the preparation of Cu nanoparticles in aqueous solution under room temperature and ambient pressure using polyvinyl alcohol (PVA) as the surfactant. The influences of the pH on the products were studied by X-ray diffraction (XRD), and those of the surfactant PVA concentration on the particle size and agglomeration by ultraviolet–visible spectrophotometry (UV–vis) and laser scattering particle size distribution analysis (LSPSDA). The products were characterized by XRD and transmission electron microscopy (TEM). The results showed that the grain size of Cu nanoparticles, within a certain range, can decrease with increasing PVA concentration. Pure Cu nanoparticles with the grain size distribution of 5–50 nm were prepared when the pH was adjusted between 5.0 and 9.0, and the PVA concentration was 2.20 g/100 mL.

The time dependence of water vapour absorption by superabsorbent polymer clay composite (SAPC) hydrogels was studied using thermophysical methods. For the purpose of comparison the average value of the specific interaction enthalpy of liquid water with the SAPC structure was calorimetrically determined for a defined interaction time. Dynamic vapour absorption measurements confirmed that the SAPC material has a sufficiently high absorption capacity and good selectivity for water vapour. A prototype moisture sensor with excellent reproducibility of the output voltage signal was constructed by coating a silicon integrated thermotransducer with a thin SAPC membrane.

Dynamic and transient rheological properties were measured for a series of hydrogel composites whose microstructure has been reported previously. These hydrogels, composed of radiation-crosslinked polyacrylamide and bentonite clay particles acting as polymer-absorbing mechanical crosslink sites, were prepared in the range 50–95% water. Dynamic storage and loss moduli (G′, G′′) were obtained at several strain amplitudes, over a range of frequency (ω) from 10-2 to 102 rad/s. Step strains produced stress peaks and decays interpreted in terms of the stress relaxation modulus, carried to 104 s. Rheological complications with possible slip, yielding, and nonlinearities were avoided but are discussed in detail. Rubberlike rheology was exhibited in general, and G′ found to depend exponentially on solids content, with parameters only weakly dependent on ω. A practical measure of gel strength, defined in terms of the size of a water-containing cube that is mechanically stable, is used to demonstrate that these gels have considerable strength, with even a 1-m cube stable at 80% water.

The structure of superabsorbent poly(acrylamide)-clay-based composite (SAPC) was studied by means of XRD, SEM, NMR, FTIR, TGA and DSC. The study showed that the acrylamide was intercalated in the lamina of clay in bimolecular layers. The hydrogels exhibited typical viscoelastic properties. The composite showed a strong response to changes in ionic environment (pH) and electric field strength, as well as chemomechanical properties.

The radiation-induced condensation reaction of urea and formaldehyde was studied in aerated aqueous solution containing chloral hydrate. The polymerization is predominantly initiated by hydrochloric acid produced from chloral hydrate and is accelerated at high temperatures. The polymer yield was highest at the formaldehyde/urea (F/U) ratio of 1. The C/N ration in the polymer increased with increasing F/U ratio but was constant above F/U = 2. The i.r. spectra of the polymers obtained at different F/U ratios are presented.

Radiation-induced polymerization of sodium p-styrenesulphonate in aqueous solution is accelerated by γ-cyclodextrin and is inhibited by α-cyclodextrin through binding of the propagating radical chain ends into the cyclodextrin cavities.