Hysteresis‐Free 1D Network Mixed Halide‐Perovskite Semitransparent Solar Cells

The morphology of hybrid organic–inorganic perovskite films is known to strongly affect the performance of perovskite‐based solar cells. CH₃NH₃PbI_3‐xCl_x (MAPbI_3‐xCl_x) films have been previously fabricated with 100% surface coverage in glove boxes. In ambient air, fabrication generally relies on solvent engineering to obtain compact films. In contrast, this work explores the potential of altering the perovskites microstructure for solar cell engineering. This work starts with CH₃NH₃PbI_3‐xCl_x, films with grain morphology carefully controlled by varying the deposition speed during the spin‐coating process to fabricate efficient and partially transparent solar cells. Devices produced with a CH₃NH₃PbI_3‐xCl_x film and a compact thick top gold electrode reach a maximum efficiency of 10.2% but display a large photocurrent hysteresis. As it is demonstrated, the introduction of different concentrations of bromide in the precursor solution addresses the hysteresis issues and turns the film morphology into a partially transparent interconnected network of 1D microstructures. This approach leads to semitransparent solar cells with negligible hysteresis and efficiencies up to 7.2%, while allowing average transmission of 17% across the visible spectrum. This work demonstrates that the optimization of the perovskites composition can mitigate the hysteresis effects commonly attributed to the charge trapping within the perovskite film.     

At-Rest Earth Pressure of Overconsolidated Cohesionless Soil

Earth pressure theories occupy a paramount position in the field of geotechnical engineering. An experimental investigation of the at-rest earth pressure of overconsolidated cohesionless soil acting on retaining walls was conducted. A prototype model of a vertical rough wall, retaining horizontal backfill, was developed in the laboratory. The model was instrumented to measure the earth pressure at selected points on the wall, the total earth force acting on the wall, and the overconsolidation ratio (OCR) in the sand mass. Tests were conducted on walls retaining homogeneous overconsolidated dense, medium, or loose sands. Test results showed that the coefficient of at-rest earth pressure increases with the increase of the OCR. The present experimental results were used to examine the empirical formulas available in the literature. It can be reported that these formulas compared well with the experimental results for OCR values up to 3. An empirical formula is proposed to predict the coefficient of at-rest earth pressure for overconsolidated cohesionless soils. The results obtained by this formula agreed well with the present experimental results for all values of overconsolidation ratios.     

Analysis and design of ferrite cores for eddy-current-killedoscillator inductive proximity sensors

Finite element modeling of ferrite cores used in the design of eddy-current-killed oscillator inductive proximity sensors was performed. Based on contemplation of the practical operation of the sensors, ferrite core geometries were compared with a reference core by the eddy-current power loss in a metal target at a fixed distance from the face of each transducer. Several of these cores were experimentally evaluated for sensing distance to verify the results of the simulation. It was observed that, for fixed coil, fixed target distance, and given target, the low-frequency sensing distance of a particular transducer is approximately proportional to the fourth root of eddy-current power loss in the target     

Phytochemical and biological investigation of <Emphasis Type="Italic">Stevia rebaudiana</Emphasis> Bertoni; 1-labdane-type diterpene

Five labdane diterpenoids, austroinulin, iso-austroinulin, sterebin E, sterebin E acetate, and sterebin A acetate, along with hydrocarbons, aliphatic alcohols, β-amyrin, β-sitosterol and stigmasterol were isolated from the chloroform soluble fraction of the methanol extract of Stevia rebaudiana leaves. Chlorogenic and caffeic acids were isolated from the EtOAc fraction. All the isolated compounds were identified using spectral tools. The chloroform and methanol extracts proved significant anti-inflammatory effect and caused marked inhibition of carrageenan-induced paw oedema in rats.     

A Genetic Algorithm-Based,Dynamic Clustering Method Towards Improved WSN Longevity

The dynamic nature of wireless sensor networks (WSNs) and numerous possible cluster configurations make searching for an optimal network structure on-the-fly an open challenge. To address this problem, we propose a genetic algorithm-based, self-organizing network clustering (GASONeC) method that provides a framework to dynamically optimize wireless sensor node clusters. In GASONeC, the residual energy, the expected energy expenditure, the distance to the base station, and the number of nodes in the vicinity are employed in search for an optimal, dynamic network structure. Balancing these factors is the key of organizing nodes into appropriate clusters and designating a surrogate node as cluster head. Compared to the state-of-the-art methods, GASONeC greatly extends the network life and the improvement up to 43.44 %. The node density greatly affects the network longevity. Due to the increased distance between nodes, the network life is usually shortened. In addition, when the base station is placed far from the sensor field, it is preferred that more clusters are formed to conserve energy. The overall average time of GASONeC is 0.58 s with a standard deviation of 0.05.     

Electrical and Optical Properties of Transparent Conducting p‐Type SrTiO3 Thin Films

We report a systematic study of the electrical and optical properties of epitaxial perovskite p‐type In‐doped SrTiO₃ thin films (SrIn_xTi_1?xO₃, 0 ≤ x ≤ 0.15) grown on single‐crystal (100)‐oriented LaAlO₃ substrates using a hybrid method which combines pulsed laser deposition and molecular beam epitaxy in a range of deposition conditions. X‐ray diffraction analysis confirms the epitaxial growth of high crystal quality films. Four‐point probe and Hall Effect measurements demonstrate that the films are p‐type semiconductors with a low resistivity of ~10^?2 Ω·cm and a high carrier concentration of ~10¹⁹ cm^?3. The optical transmittance spectra reveal that the films are highly transparent (?70%) in the visible region.     

Ultrafast Microwave Hydrothermal Synthesis of BiFeO3 Nanoplates

We report the synthesis of {100}_c facets exposed single‐crystalline BiFeO₃ (BFO) nanoplates, with thickness ranging from 20 to 160 nm and lateral size of submicrometers, via a simple and very rapid (1–2 min) microwave‐assisted hydrothermal approach. We show that the microwave treatment gives comparable improvement in crystallinity of BFO nanocrystals with respect to traditional hydrothermal processes while requiring significantly less time and energy. In addition, we show that microwave radiation power, reaction time, and alkali concentration play important roles in the crystallinity and morphology of the products. We discuss a possible formation mechanism of the nanoplates based on our experimental results. Additionally, the BFO nanoplates exhibit weak ferromagnetic properties at room temperature, which we attribute to the size‐confinement effect on magnetic ordering. The present microwave hydrothermal method has great potential in large‐scale fabrication of BFO nanomaterials as well as other composite functional materials due to significantly reduced time and energy.