Establishment of an absolute measurement of the reference air kerma rate for HDR Ir brachytherapy sources.

Purpose: Before this study, no institution in China had undertaken the calculation and official establishment of reference values for the reference air kerma rate associated with high-dose rate Ir sources used in brachytherapy. This research, carried out at the National Institute of Metrology (NIM) in China, has successfully established an Ir reference radiation facility. Consequently, it has achieved the absolute measurement of the reference air kerma rate for high-dose rate brachytherapy using Ir sources.

Half-metallization Atom-Fingerprints Achieved at Ultrafast Oxygen-Evaporated Pyrochlores for Acidic Water Oxidation.

The stability and catalytic activity of acidic oxygen evolution reaction (OER) are strongly determined by the coordination states and spatial symmetry among metal sites at catalysts. Herein, an ultrafast oxygen evaporation technology to rapidly soften the intrinsic covalent bonds using ultrahigh electrical pulses is suggested, in which prospective charged excited states at this extreme avalanche condition can generate a strong electron-phonon coupling to rapidly evaporate some coordinated oxygen (O) atoms, finally leading to a controllable half-metallization feature. Simultaneously, the relative metal (M) site arrays can be orderly locked to delineate some intriguing atom-fingerprints at pyrochlore catalysts, where the coexistence of metallic bonds (M─M) and covalent bonds (M─O) at this symmetry-breaking configuration can partially restrain crystal field effect to generate a particular high-spin occupied state.

A Noncentrosymmetric Metal-Free Borophosphate: Achieving a Large Birefringence and Excellent Stability by Covalent-Linkage.

Organic-inorganic hybrid linear and nonlinear optical (NLO) materials have received increasingly wide spread attention in recent years. Herein, the first hybrid noncentrosymmetric (NCS) borophosphate, (CHN)BO(HPO) (4PBP), is rationally designed and synthesized by a covalent-linkage strategy. 4-pyridyl-boronic acid (4 PB) is considered as a bifunctional unit, which may effectively improve the optical properties and stability of the resultant material.

Building (001) oriented FAPbI films for high-performing perovskite solar cells.

The solution processed FAPbI perovskite usually suffers from chaotic orientations. Herein, a template structure of oriented 2D perovskite is used to obtain a high-quality FAPbI film with (001) preferred orientation by cation exchange. The highly oriented BAPbI serves as a growth template and promotes the (001) orientation of the 3D perovskite.

Interfacial engineering eliminates energy loss at perovskite/HTL junction.

Realizing efficient FAPbI-based devices with high open-circuit voltage () is still challenging, due to severe energy loss between the n-type perovskite and p-type hole-transporting layer (HTL). Here, we developed a strategy involving controlling the formation of iodine vacancies in order to induce formation of p-type perovskite and hence mitigate such energy loss. Post-deposition of -butylamine iodide was discovered to induce an n-to-p-type transition in the FAPbI perovskite and hence form the p-type perovskite/p-type HTL junction.

SbO(TeO)(HSO)(OH): An Antimony Tellurite Sulfate Exhibiting Large Optical Anisotropy Activated by Lone Pair Stereoactivity.

A new birefringent crystal of SbO(TeO)(HSO)(OH) was achieved by incorporating two stereochemically active lone pair (SCALP) cations of Sb(III) and Te(IV) into sulfates simultaneously. The Sb and Te ions display highly distorted coordination environments due to the SCALP effect. SbO(TeO)(HSO)(OH) displays a 3D structure composed of [SbO(TeO)(OH)] layers bridged by [SO(OH)] tetrahedra.

A Dual-Functional Fibrous Skeleton Implanted with Single-Atomic Co-N Dispersions for Longevous Li-S Full Batteries.

Although lithium-sulfur (Li-S) batteries have long been touted as next-generation energy storage devices, the rampant dendrite growth at the anode side and sluggish redox kinetics at the cathode side drastically impede their practical application. Herein, a dual-functional fibrous skeleton implanted with single-atom Co-N dispersion is devised as an advanced modificator to realize concurrent regulation of both electrodes. The rational integration of single-atomic Co-N sites could convert the fibrous carbon skeleton from lithiophobic to lithiophilic, helping assuage the dendritic formation for the Li anode.

Linear and Nonlinear Optical Properties of Centrosymmetric SbOSO and Noncentrosymmetric SbO(SO)(OH) Induced by Lone Pair Stereoactivity.

Introducing stereochemically active lone-pair Sb cations into sulfates, two three-dimensional (3D) antimony-sulfates, SbOSO () and SbO(SO)(OH) (), were achieved under moderate hydrothermal conditions. Both structures are constructed by tetranuclear-{Sb}-clusters-based layers and SO tetrahedra. However, owing to the different packing patterns of the layers, they display different characteristics: exhibits a centrosymmetric structure while possesses a noncentrosymmetric structure.

In Situ Tracking of Wetting-Front Transient Heat Release on a Surface-Mounted Metal-Organic Framework.

Transient heat generation during guest adsorption and host-guest interactions is a natural phenomenon in metal-organic framework (MOF) chemistry. However, in situ tracking of such MOF released heat is an insufficiently researched field due to the fast heat dissipation to the surroundings. Herein, a facile capillary-driven liquid-imbibition approach is developed for in situ tracking of transient heat release at the wetting front of surface-mounted MOFs (SURMOFs) on cellulosic fiber substrates.

Sb O (SO ) : A Promising Ultraviolet Nonlinear Optical Material with an Enhanced Second-Harmonic-Generation Response Activated by Sb Lone-Pair Stereoactivity.

The stereochemical activity of lone pairs (SCALP) in a cation favors the formation of acentric materials and can enhance the second-harmonic-generation (SHG) response and/or the birefringence. By introducing functional Sb into sulfates, an anhydrous sulfate of Sb O (SO ) (1) is explored. Sb cations are in seesaw configurations and in-phase aligned in a 3D asymmetric dense structure.

Valley Polarization and Valleyresistance in a Monolayer Transition Metal Dichalcogenide Superlattice.

A significant, fundamental challenge in the field of valleytronics is how to generate and regulate valley-polarized currents in practical ways. Here, we discover a new mechanism for producing valley polarization in a monolayer transition metal dichalcogenide superlattice, in which valley-resolved gaps are formed at the supercell Brillouin zone boundaries and centers due to intervalley scattering. When the incident energy of the electron lies in the gaps, the available states are valley polarized, thus providing a valley-polarized current from the superlattice.

Inorganic photovoltaic cells based on BiFeO: spontaneous polarization, lattice matching, light polarization and their relationship with photovoltaic performance.

Inorganic ferroelectric perovskite oxides are more stable than hybrid perovskites. However, their solar energy harvesting efficiency is not so good. Here, by constructing a series of BiFeO3-based devices (solar cells), we investigated three factors that influence the photovoltaic performance, namely, spontaneous polarization, terminated ion species in the interface between BiFeO3 and the electrode, and polarized light irradiation.

One-step synthesis, electronic structure, and photocatalytic activity of earth-abundant visible-light-driven FeAlO.

The development of inexpensive visible-light-driven photocatalysts is an important prerequisite for realizing the industrial application of photocatalysis technology. In this paper, an earth-abundant FeAlO photocatalyst is prepared via facile solution combustion synthesis. Density functional theory and the scanning Kelvin probe technique are employed to ascertain the positions of the energy bands and the Fermi level.

Realization of Valley and Spin Pumps by Scattering at Nonmagnetic Disorders.

The recent success in optical pumping of valley polarization in two-dimensional transition metal dichalcogenides (TMDs) has greatly promoted the concept of valley-based informatics and electronics. However, between the demonstrated valley polarization of transient electron-hole pair excitations and practical valleytronic operations, there exist obvious gaps to fill, among which is the valley pump of long-lived charge carriers. Here we discover that the quested valley pump of electrons or holes can be realized simply by scattering at the ubiquitous nonmagnetic disorders, not relying on any specific material property.

Measurable spin-polarized current in two-dimensional topological insulators.

We propose a simple method for generating a spin-polarized current in a two-dimensional topological insulator. As z-component magnetic impurities exist on one edge of the Kane-Mele model, a subgap is opened in the corresponding pair of edge states, but another pair of gapless edge states is still protected by the time reversal symmetry. Thus the conductance plateau with the value e(2)/h in the subgap corresponds to a single-edge and spin-polarized current.