Structural phase purification of bulk HfO2:Y through pressure cycling.

We combine synchrotron-based infrared absorption and Raman scattering spectroscopies with diamond anvil cell techniques and first-principles calculations to explore the properties of hafnia under compression. We find that pressure drives HfO[Formula: see text]:7%Y from the mixed monoclinic ([Formula: see text]) [Formula: see text] antipolar orthorhombic ([Formula: see text]) phase to pure antipolar orthorhombic ([Formula: see text]) phase at approximately 6.3 GPa. This transformation is irreversible, meaning that upon release, the material is kinetically trapped in the [Formula: see text] metastable state at 300 K. Compression also drives polar orthorhombic ([Formula: see text]) hafnia into the tetragonal ([Formula: see text]) phase, although the latter is not metastable upon release. These results are unified by an analysis of the energy landscape. The fact that pressure allows us to stabilize targeted metastable structures with less Y stabilizer is important to preserving the flat phonon band physics of pure HfO[Formula: see text].

Elementary excitations of single-photon emitters in hexagonal boron nitride.

Single-photon emitters serve as building blocks for many emerging concepts in quantum photonics. The recent identification of bright, tunable and stable emitters in hexagonal boron nitride (hBN) has opened the door to quantum platforms operating across the infrared to ultraviolet spectrum. Although it is widely acknowledged that defects are responsible for single-photon emitters in hBN, crucial details regarding their origin, electronic levels and orbital involvement remain unknown. Here we employ a combination of resonant inelastic X-ray scattering and photoluminescence spectroscopy in defective hBN, unveiling an elementary excitation at 285 meV that gives rise to a plethora of harmonics correlated with single-photon emitters. We discuss the importance of N π* anti-bonding orbitals in shaping the electronic states of the emitters. The discovery of elementary excitations in hBN provides fundamental insights into quantum emission in low-dimensional materials, paving the way for future investigations in other platforms.

Excitations of Intercalated Metal Monolayers in Transition Metal Dichalcogenides.

We combine Raman scattering spectroscopy and lattice dynamics calculations to reveal the fundamental excitations of the intercalated metal monolayers in the FexTaS2 (x = 1/4, 1/3) family of materials. Both in- and out-of-plane modes are identified, each of which has trends that depend upon the metal-metal distance, the size of the van der Waals gap, and the metal-to-chalcogenide slab mass ratio. We test these trends against the response of similar systems, including Cr-intercalated NbS2 and RbFe(SO4)2, and demonstrate that the metal monolayer excitations are both coherent and tunable. We discuss the consequences of intercalated metal monolayer excitations for material properties and developing applications.

Large Positive Zero-Field Splitting in the Cluster Magnet Ba3CeRu2O9.

We present the synthesis and magnetic characterization of a polycrystalline sample of the 6H-perovskite Ba3CeRu2O9, which consists of Ru dimers based on face-sharing RuO6 octahedra. Our low-temperature magnetic susceptibility, magnetization, and neutron powder diffraction results reveal a nonmagnetic singlet ground state for the dimers. Inelastic neutron scattering, infrared spectroscopy, and the magnetic susceptibility over a wide temperature range are best explained by a molecular orbital model with a zero-field splitting parameter D = 85 meV for the Stot = 1 electronic ground-state multiplet. This large value is likely due to strong mixing between this ground-state multiplet and low-lying excited multiplets, arising from a sizable spin molecular orbital coupling combined with an axial distortion of the Ru2O9 units. Although the positive sign for the splitting ensures that Ba3CeRu2O9 is not a single molecule magnet, our work suggests that the search for these interesting materials should be extended beyond Ba3CeRu2O9 to other molecular magnets based on metal-metal bonding.

Potential Global Distribution of Paracoccus marginatus, under Climate Change Conditions, Using MaxEnt.

The papaya mealybug, Paracoccus marginatus, is an invasive pest species found all over the world. It is native to Mexico and Central America, but is now present in more than 50 countries and regions, seriously threatening the economic viability of the agricultural and forestry industry. In the current study, the global potential distribution of P. marginatus was predicted under current and future climatic conditions using MaxEnt. The results of the model assessment indicated that the area under the curve of the receiver operating characteristic ( ROC-AUC) was 0.949, while the TSS value was 0.820. The results also showed that the three variables with the greatest impact on the model were min temperature of coldest month (bio6), precipitation of wettest month (bio13), and precipitation of coldest quarter (bio19), with corresponding contributions of 46.8%, 31.1%, and 13.1%, respectively. The results indicated that the highly suitable areas were mainly located in tropical and subtropical regions, including South America, southern North America, Central America, Central Africa, Australia, the Indian subcontinent, and Southeast Asia. Under four climate scenarios in the 2050s and 2070s, the area of suitability will change very little. Moreover, the results showed that the area of suitable areas in 2070s increased under all four climate scenarios compared to the current climate. In contrast, the area of suitable habitat increases from the current to the 2050s under the SSP370 and SSP585 climate scenarios. The current study could provide a reference framework for the future control and management of papaya mealybug and other invasive species.

Magnetic excitations in strained infinite-layer nickelate PrNiO2 films.

Strongly correlated materials respond sensitively to external perturbations such as strain, pressure, and doping. In the recently discovered superconducting infinite-layer nickelates, the superconducting transition temperature can be enhanced via only ~ 1% compressive strain-tuning with the root of such enhancement still being elusive. Using resonant inelastic x-ray scattering (RIXS), we investigate the magnetic excitations in infinite-layer PrNiO2 thin films grown on two different substrates, namely SrTiO3 (STO) and (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) enforcing different strain on the nickelates films. The magnon bandwidth of PrNiO2 shows only marginal response to strain-tuning, in sharp contrast to the enhancement of the superconducting transition temperature Tc in the doped superconducting samples. These results suggest the bandwidth of spin excitations of the parent compounds is similar under strain while Tc in the doped ones is not, and thus provide important empirics for the understanding of superconductivity in infinite-layer nickelates.

Deep learning and radiomics of longitudinal CT scans for early prediction of tuberculosis treatment outcomes.

BACKGROUND: To predict tuberculosis (TB) treatment outcomes at an early stage, prevent poor outcomes ofdrug-resistant tuberculosis(DR-TB) and interrupt transmission. METHODS: An internal cohort for model development consists of 204 bacteriologically-confirmed TB patients who completed anti-tuberculosis treatment, with one pretreatment and two follow-up CT images (612 scans). Three radiomics feature-based models (RM) with multiple classifiers of Bagging, Random forest and Gradient boosting and two deep-learning-based models (i.e., supervised deep-learning model, SDLM; weakly supervised deep-learning model, WSDLM) are developed independently. Prediction scores of RM and deep-learning models with respectively highest performance are fused to create new fusion models under different fusion strategies. An additional independent validation was conducted on the external cohort comprising 80 patients (160 scans). RESULTS: For RM scheme, 16 optimal radiomics features are finally selected using longitudinal scans. The AUCs of RM for Bagging, Random forest and Gradient boosting were 0.789, 0.773 and 0.764 in the internal cohort and 0.840, 0.834 and 0.816 in the external cohort, respectively. For deep learning-based scheme, AUCs of SDLM and WSDLM were 0.767 and 0.661 in the internal cohort, and 0.823 and 0.651 in the external. The fusion model yields AUCs from 0.767 to 0.802 in the internal cohort, and from 0.831 to 0.857 in the external cohort. CONCLUSIONS: Fusion of radiomics features and deep-learning model may have the potential to predict early failure outcome of DR-TB, which may be combined to help prevent poor TB treatment outcomes.

Pangenomic analysis of Chinese gastric cancer.

Pangenomic study might improve the completeness of human reference genome (GRCh38) and promote precision medicine. Here, we use an automated pipeline of human pangenomic analysis to build gastric cancer pan-genome for 185 paired deep sequencing data (370 samples), and characterize the gene presence-absence variations (PAVs) at whole genome level. Genes ACOT1, GSTM1, SIGLEC14 and UGT2B17 are identified as highly absent genes in gastric cancer population. A set of genes from unaligned sequences with GRCh38 are predicted. We successfully locate one of predicted genes GC0643 on chromosome 9q34.2. Overexpression of GC0643 significantly inhibits cell growth, cell migration and invasion, cell cycle progression, and induces cell apoptosis in cancer cells. The tumor suppressor functions can be reversed by shGC0643 knockdown. The GC0643 is approved by NCBI database (GenBank: MW194843.1). Collectively, the robust pan-genome strategy provides a deeper understanding of the gene PAVs in the human cancer genome.

Identifying Potentially Climatic Suitability Areas for Arma custos (Hemiptera: Pentatomidae) in China under Climate Change.

Spodoptera frugiperda is a notorious pest that feeds on more than 80 crops, and has spread over 100 countries. Many biological agents have been employed to regulate it, such as Arma custos. A. custos is a polyphagous predatory heteropteran, which can effectively suppress several agricultural and forest pests. Thus, in order to understand where A. custos can survive and where can be released, MaxEnt was used to predict the potentially suitable areas for A. custos in China under climate change conditions. The results show that the annual mean temperature (bio1) and annual precipitation (bio12) are the major factors influencing the distribution of A. custos. The optimal range of the two are 7.5 to 15 °C, 750 to 1200 mm, respectively. The current climate is highly suitable for A. custos in Hebei, Henan, Shandong, Anhui, Hubei, Jiangsu, and Zhejiang Provinces. Considering the currently suitable distribution area of S. frugiperda, artificially reared A. custos is suitable for release in Fujian, Zhejiang, Jiangxi, Hunan, and southeastern Sichuan Provinces. Under the future climatic scenarios, the suitable area will decrease and shift towards the north. Overall, this result can provide a reference framework for future application of A. custos for biological control.

Site-specific spectroscopic measurement of spin and charge in (LuFeO3)m/(LuFe2O4)1 multiferroic superlattices.

Interface materials offer a means to achieve electrical control of ferrimagnetism at room temperature as was recently demonstrated in (LuFeO3)m/(LuFe2O4)1 superlattices. A challenge to understanding the inner workings of these complex magnetoelectric multiferroics is the multitude of distinct Fe centres and their associated environments. This is because macroscopic techniques characterize average responses rather than the role of individual iron centres. Here, we combine optical absorption, magnetic circular dichroism and first-principles calculations to uncover the origin of high-temperature magnetism in these superlattices and the charge-ordering pattern in the m = 3 member. In a significant conceptual advance, interface spectra establish how Lu-layer distortion selectively enhances the Fe2+ â†’  Fe3+ charge-transfer contribution in the spin-up channel, strengthens the exchange interactions and increases the Curie temperature. Comparison of predicted and measured spectra also identifies a non-polar charge ordering arrangement in the LuFe2O4 layer. This site-specific spectroscopic approach opens the door to understanding engineered materials with multiple metal centres and strong entanglement.

[Seasonal Variations of DOM Spectral Characteristics in the Surface Water of the Upstream Minjiang River].

Alpine wetlands and valleys of northwestern Sichuan are the main catchment areas of Minjiang River, where dissolved organic matter (DOM) in surface waters comes mainly from the natural background environment. Sources and structure parameters of DOM are important for calibrating the flux and pattern of organic carbon exports from plateau wetlands and alpine rivers. In this study, surface water samples along the upstream Minjiang River were collected at the end of dry season (April) and rainy season (October). Excitation emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) was used to characterize seasonal variations of DOM along Minjiang River. Results showed fluorescence peaks (humic-like peaks A and C, protein-like peaks B and T) were different along the river. Peak A and peak C were more obvious at the end of dry season, while peak B and peak T were more obvious at the end of rainy season. PARAFAC produced a three-component model including two humic-like components[C1 (250-260/380-480 nm) and C2 (300-330/380-480 nm)] and one protein-like component[C3 (270-280/300-350 nm)], accounting relative intensity 48.68%-65.02% for C1, 23.17%-29.83% for C2, and 11.83%-21.53% for C3. Fluorescence components showed variations along the river more prominently in April than October, in which the most significant one was C1. Average fluorescence index (FI) values ranged from 1.4 to 1.9, indicating that DOM consisted of both autochthonous and allochthonous components. Moreover, higher degrees of humification, aromaticity and hydrophobicity were found in April than those in October, suggesting more terrigenous sources at the end of dry season and more biological sources at the end of rainy season. Additionally, chromophoric dissolved organic matter (CDOM)[a(355)] correlated significantly with humic-like substance[Fn(355)], which also indicated that DOM components originated from terrigenous input in the upstream Minjiang River. The results also showed significant positive correlation between C1 and C2 in April, with no significant correlation in October, which further proved that exogenous input and seasonal variations characterized DOM sources in the upstream Minjiang River.

Magnetic field control of charge excitations in CoFe2O4.

We combine magnetic circular dichroism and photoconductivity with prior optical absorption and first principles calculations to unravel spin-charge interactions in the high Curie temperature magnet CoFe2O4. In addition to revising the bandgap hierarchy, we reveal a broad set of charge transfer excitations in the spin down channel which are sensitive to the metamagnetic transition involving the spin state on Co centers. We also show photoconductivity that depends on an applied magnetic field. These findings open the door for the creation and control of spin-polarized electronic excitations from the minority channel charge transfer in spinel ferrites and other earth-abundant materials.

[Characteristics of Chromophoric Dissolved Organic Matter (CDOM) in Rivers of Western Sichuan Plateau Based on EEM-PARAFAC Analysis].

Alpine meadows and wetlands of western Sichuan plateau are essential organic carbon pools for Tibetan plateau; thus, a thorough understanding of the characteristics of dissolved organic carbon (DOC) and its association with soil carbon storage pool helps to reveal the flux and intensity of DOC export in the area. Surface water samples were collected from three rivers (the upper reaches of Min River, Zagunao River, and Fubian River) in the alpine-gorge region and Bai River in the plateau planation surface distributed among the watersheds in western Sichuan plateau, Southwest China. UV absorbance and EEM fluorescence spectroscopy with parallel factor analysis (PARAFAC) was used to characterize chromophoric dissolved organic matter (CDOM). PARAFAC produced a three-component model:C1(260/480) and C2(310/420) represented terrestrial humic-like fluorophores, and C3(280/370) belonged to tyrosine-like substances. The total fluorescence intensity of CDOM in the alpine-gorge region showed fewer changes along the rivers and was lower than that of the Bai River in the hilly plateau. The Bai River had much higher concentrations of humic-like substances (C1,C2) compared to the other three rivers, indicating its terrestrial sources with high humification degree originated from meadows and watersheds along the river. The calculated fluorescence indices (FI, BIX, HIX, ß:α) showed that CDOM in the alpine-gorge region was a mixture with both autochthonous and allochthonous origins with low humification degree, while CDOM in the plateau planation surface had a higher degree of humification and lower extent of degradation. Statistical analysis showed that the C1 and C2 components in four rivers were significantly positively correlated, and C1, C2 and C3 components in Bai River were significantly positively correlated. ß:α and BIX were significantly positively correlated in four rivers, but there was no significant correlation between DOC and CDOM[a(355)].