ABSTRACT
Two-dimensional van der Waals heterostructures (2D-vdWHs) based on transition metal dichalcogenides (TMDs) provide unparalleled control over electronic properties. However, the interlayer coupling is challenged by the interfacial misalignment and defects, which hinders a comprehensive understanding of the intertwined electronic orders, especially superconductivity and charge density wave (CDW). Here, by using pressure to regulate the interlayer coupling of non-centrosymmetric 6R-TaS2 vdWHs, we observe an unprecedented phase diagram in TMDs. This phase diagram encompasses successive suppression of the original CDW states from alternating H-layer and T-layer configurations, the emergence and disappearance of a new CDW-like state, and a double superconducting dome induced by different interlayer coupling effects. These results not only illuminate the crucial role of interlayer coupling in shaping the complex phase diagram of TMD systems but also pave a new avenue for the creation of a novel family of bulk heterostructures with customized 2D properties.
ABSTRACT
One-step purification of ethylene from ternary mixtures (C2H2, C2H4, and C2H6) can greatly reduce the energy consumption of the separation process, but it is extremely challenging. Herein, we use crystal engineering and reticular chemistry to introduce unsaturated bonds (ethynyl and alkyne) into ligands, and successfully design and synthesized two novel Zr-MOCs (ZrT-1-ethenyl and ZrT-1-alkyne). The introduction of carbon-carbon unsaturated bonds provides abundant adsorption sites within the framework while modulating the pore window size. Comprehensive characterization techniques including single crystal and powder X-ray diffraction, as well as electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) confirm that ZrT-1-ethenyl and ZrT-1-alkyne possess an isostructural framework with ZrT-1 and ZrT-1-Me, respectively. Adsorption isotherms and breakthrough experiments combined with theoretical calculations demonstrate that ZrT-1-ethenyl can effectively remove trace C2H2 and C2H6 in C2H4 and achieve separation of C2H2 from C2H4 and CO2. ZrT-1-ethenyl can also directly purify C2H4 in liquid solutions. This work provides a benchmark for MOCs that one-step purification of ethylene from ternary mixtures.
ABSTRACT
BACKGROUND: On 6 February 2023, an Mw 7.8 earthquake struck southern and central Türkiye and north-western Syria, affecting the lives of 4.6 and 2.5 million children, respectively. In such crises, infants who are dependent on commercial milk formula (CMF) face increased vulnerability to diseases and malnutrition as safe preparation of CMF becomes difficult and sometimes impossible. The Operational Guidance on Infant and Young Child Feeding in Emergencies (OG-IFE) provides guidance on protecting and supporting recommended infant and young child feeding and minimizing the risks that come with CMF feeding. In addition, the International Code of Marketing of Breastmilk Substitutes (the Code) ensures adequate nutrition for infants by protecting and promoting breastfeeding and ensuring the proper usage of CMF. This study aims to document violations of the Code and the OG-IFE during the earthquake relief efforts to help strengthen infant and young child feeding emergency responses and inform future disaster relief policies. METHODS: Data was collected from 6 February to 10 March 2023 through Internet sources. Social media, news websites, and the Emergency Nutrition Network forum were used for data collection. Turkish content was translated into English for analysis, with a focus on donation-related information and Code violations related to baby food and infant feeding. RESULTS: A total of 40 reports on CMF, complementary food, and feeding equipment donations were collected. Three main types of violations of the OG-IFE and the Code were identified, with the majority of them being incidences of individuals, humanitarian organizations, and government agencies seeking or accepting donations. Infant formula companies continued to violate the Code by donating large quantities of CMF and feeding equipment to the Turkish Red Crescent, government agencies, and disaster relief infant and young child feeding (IYCF) coordination authorities. CONCLUSIONS: These incidents reflected a systematic violation of the Code and non-compliance with the OG-IFE. Globally accepted IYCF standards and recommendations were not consistently followed due to fragmented early responses. There is a critical need to step up efforts to ensure appropriate and safe IYCF practice protecting and supporting breastfed and non-breastfed infants in emergencies.
Subject(s)
Earthquakes , Infant Formula , Relief Work , Humans , Infant , Female , Turkey , Infant, Newborn , Breast Feeding , Syria , MaleABSTRACT
Obtaining a perovskite light-absorbing layer with good crystallization, low defect concentration, good stability, and well-matched energy levels is critical to obtaining high-efficiency perovskite solar cells (PSCs). Here, a hybrid PSC with a graded band gap is explored using MAPbBr3 (MA = CH3NH3) and MAPbBr0.9I2.1 quantum dots (QDs) as component cells. We have creatively designed a solar cell device with a double-QD structure [indium tin oxide (ITO)/SnO2/perovskite:MAPbBr3 QDs/MAPbBr0.9I2.1 QDs/Spiro-OMeTAD/Au]. A better crystal film of the perovskite absorption layer can be obtained because the MAPbBr3 QDs are doped in an antisolvent, which induces nucleation and growth in the polycrystalline perovskite. In addition, we expect that digestive ripening occurred in the crystallization, and the oleic acid ligands on the surface of the QDs disintegrate during the doping process and transfer to the surface of the perovskite absorption layer finally; it follows that the hydrophobicity and stability of the perovskite film are greatly enhanced. Moreover, a thin film of MAPbBr0.9I2.1 QDs is introduced between the perovskite absorption layer and the hole layer, acting as an energy-level ladder, which leads to well-matched energy levels, an increase in fill factor (FF), and an enhanced hole transport capability. In particular, the mechanism of the crystallization process involving the effect of oleic acid ligands on the interior and surface of the perovskite film is fully discussed here. The final research results from the PSCs show that both high efficiency and long-term stability are achieved successfully by this design strategy.
ABSTRACT
The adsorption ability and photoactivity of a photocatalyst largely determine the mineralization efficiency of antibiotics. Herein, aiming to enhance the adsorption and mineralization of antibiotics, we constructed a hierarchical porous core-shell structure by filling amorphous TiO2 in the pores of Pt-doped mesoporous TiO2 crystals (MCs). The physical-chemical properties of the prepared samples were investigated by surface photovoltage spectroscopy, X-ray photoelectron spectroscope, etc. Adsorption and photocatalysis experiments were conducted with tetracycline hydrochloride as the model antibiotic. Pt nanoparticles doped at the interface of the rutile-amorphous homojunction remarkably enhanced the built-in electric field. The enhanced electric field increased the hole transfer to the catalyst surface, and the Pt doping treatment promoted the growth of amorphous TiO2 into the mesopores of the MCs. The optimization increased the surface area of the catalyst without increasing the thickness of the amorphous TiO2 shell, thereby reducing the charge migration distance from the core-shell interface to the catalyst surface. The adsorption amount and mineralization efficiency of tetracycline hydrochloride for the porous core-shell composite were 6.7 and 3.8 times of those for MCs, respectively.