Search

To improve the stability of solar heating and reduce the high cost of air source heat pump heating, the idea of air source heat pump assisted solar stable heating was proposed. A solar vacuum tube water heater-air source heat pump system was developed and bulit in Weiling Township, Qilihe District, Lanzhou, Gansu Province. The performance of the system was compared to analyze the heat collection efficiency, heat pump coefficient of performance (COP), solar energy guarantee rate, and energy efficiency ratio under sunny, overcast, and cloudy conditions. The results show that the effective heat obtained by solar energy under sunny, overcast, and cloudy conditions is 75.5 kW·h, 4.1 kW·h, and 49.2 kW·h respectively, the system heat collection efficiency is 61.3%, 26.6%, and 55.2%, the average coefficient of performance(COP) of the solar heat pump is 3.6, 3.4, and 3.6, the average COP of the air source heat pump is 0, 2.9, and 3.1, the actual heat supply of the system is 113.4 kW·h, 125.9 kW·h, and 124.8 kW·h, the system power consumption is 33.4 kW·h, 50.5 kW·h, and 42.7 kW·h, the system solar energy guarantee rate is 66.6%, 3.3%, and 39.4%, and the system energy efficiency ratio is 3.4, 2.5, and 2.9 respectively. The research results prove that the solar vacuum tube collector-air source heat pump system is feasible for heating and provide a new way for heating in cold areas.

In recent years, Ag−In−Ga−S (AIGS) quaternary quantum dots (QDs) have garnered significant attention as a novel class of environmentally friendly and non‐toxic QDs. However, the hydrothermal synthesis method for aqueous QDs has been plagued by issues such as inconsistent size, subpar crystallinity, and low photoluminescence quantum yield (PLQY). Herein, we developed a dual ligand strategy based on the hard and soft acids and bases (HSAB) theory to synthesize aqueous AIGS QDs with an impressive PLQY of up to 64.3 %, currently the highest value among hydrothermal‐synthesized uncoated I–III–VI QDs. The QDs exhibit better crystallinity, narrow size distribution (3.07±0.31 nm), and remarkable stability. The mechanism underlying this dual ligand strategy was further elucidated, shedding light on the distinct influences of different ligands on the growth of QDs. The high PLQY contributes to the further application of aqueous AIGS QDs in luminescent displays and the field of biology. Meanwhile, this ligand strategy has broad reference significance for efficient preparation of other water‐soluble QDs. [ABSTRACT FROM AUTHOR]

The diagnosis of drug‐resistant tuberculosis (TB) by molecular testing of Mycobacterium tuberculosis drug resistance genes is becoming increasingly common clinically. However, M. bovis, as an uncommon pathogen of human TB, may interfere with the test results. A comprehensive understanding of phylogenetically informative mutations in the drug resistance genes of M. bovis is required to distinguish true resistance‐conferring mutations. We analyzed 53 drug resistance genes in 165 M. bovis isolated from humans using whole‐genome sequencing data and found that 98.2% (162/165) of isolates have pyrazinamide intrinsic genotypic resistance, owing to the H57D mutation in the pncA gene. 12.1% (20/165) of M. bovis isolates were resistant to drugs other than pyrazinamide. Furthermore, we discovered 18 phylogenetically informative mutations that differed between M. bovis and the major lineages 1–4 of M. tuberculosis. Additionally, we reported false‐positive ethambutol resistance caused by M. bovis infection due to the phylogenetically informative mutation embB E378A. This study is crucial for gaining insights into the genetic characterization and drug resistance of M. bovis prevalent in humans, as well as contributing to the development of more accurate molecular diagnostic methods and detection tools for drug resistance. [ABSTRACT FROM AUTHOR]

The "Nobel Prize in Chemistry 2023" is awarded to Moungi G. Bawendi, Louis E. Brus, and Alexey I. Yekimov for discovering and synthesizing Quantum Dots (QDs). Colloidal QDs possess fascinating size‐, morphological‐, composition‐, and assembly‐tunable electronic and optical properties, which makes them star materials for various optoelectronic applications, especially as luminescent materials for next‐generation wide color gamut ultra‐high‐definition displays. Perovskite QDs (PQDs) have gained widespread attention in recent years. In less than ten years, research on perovskite‐related materials and devices has basically been perfected in terms of quantum yield and external quantum efficiency (EQE). However, on the eve of its industrial application, some key technical indicators and technical processes need to be met and resolved. The development and transformation of QD materials and then focuses on the progress of luminescence linewidth and EQE of the PQD light‐emitting diode. Finally, several application avenues are reviewed for PQDs, and some challenges and opportunities in the field are proposed. [ABSTRACT FROM AUTHOR]

Quaternary Ag-In-Ga-S (AIGS) quantum dot (QD) is considered a promising, spectral-tunable, and environmentally friendly luminescent display material. However, the more complex surface defect states of AIGS QDs resulting from the coexistence of multiple elements lead to a low (< 60%) photoluminescence quantum yield (PLQY). Here, we develop a novel convenient method to introduce Z-type ligands ZnX2 (X = Cl, Br, I) for passivating the surface defects of AIGS QDs to dramatically enhance the PLQY and stability without affecting the crystalline structure and morphology. Results show that the addition of ZnCl2 during the purified process of AIGS QDs leads to a 3-fold increase of PLQY (from 28.5% to 87%). Impressively, the highest PLQY is up to a recorded value of 92%, which is comparable to typical heavy metal QDs. Exciton dynamics studies have shown that the rapid annihilation process of excitons in treated QDs is inhibited. We also confirm that the improvement in PLQY is a result of the effective passivation of the non-coordinating atom on the QD surface by building a new bonding between sulfur dangling and Zn2+. The realization of high PLQY will further promote the application of AIGS QDs in luminescent displays. [ABSTRACT FROM AUTHOR]

A novel insertion device is introduced, designated as the Mango wiggler, designed for synchrotron radiation (SR) imaging that provides a large field of view. This innovative device is constructed from two orthogonal planar wigglers with a small difference in their period lengths, eliciting the phase difference of the magnetic fields to incrementally transitions from 0 to π/2. Such a configuration enlarges the vertical divergence of the light source, as with the horizontal divergence. The appellation 'Mango wiggler' derives from the distinctive mango‐shaped contour of its radiation field. A comprehensive suite of theoretical analyses and simulations has been executed to elucidate the radiation properties of the Mango wiggler, employing SPECTRA and Mathematica as calculation tools. In conjunction with the ongoing construction of the High Energy Photon Source in Beijing a practical Mango wiggler device has been fabricated for utilization in SR imaging applications. Theoretical analyses were applied to this particular Mango wiggler to yield several theoretical conclusions, and several simulations were performed according to the measured magnetic field results. [ABSTRACT FROM AUTHOR]

G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology.