Rain use efficiency gradients across Australian ecosystems.

Rain use efficiency (RUE) quantifies the ecosystem's capacity to use precipitation water to assimilate atmospheric CO2. The spatial distribution of RUE and its drivers across the Australian continent is largely unknown. This knowledge gap limits our understanding of the possible contribution of Australian ecosystems to global carbon assimilation. This study investigates the spatial distribution of RUE across diverse terrestrial ecosystems in Australia. The results show that RUE ranges from 0.43 (1st percentile) to 3.10 (99th percentile) g C m-2 mm-1 with a continental mean of 1.19 g C m-2 mm-1. About 68 % of the spatiotemporal variability of RUE can be explained by a multiple linear regression model primarily contributed by climatic predictors. Benchmarked by the model estimation, drainage-diverging/converging landscapes tend to have reduced/increased RUE. The model also revealed the impact of increasing atmospheric CO2 concentration on RUE. The continental mean RUE would increase by between 29.3 and 64.8 % by the end of this century under the SSP5-8.5 scenario in which the CO2 concentration is projected to double from the present level. This increase in projected RUE is attributed to the assumed greening effect of increasing CO2 concentration, which does not consider the saturation of CO2 fertilisation effect and the warming effect on increasing wildfire occurrence. Under the SSP1-2.6 scenario, RUE would decrease by about 7 %. This study provides baseline RUEs of various ecosystems in Australia for investigating the impacts of human interferences and climate change on the capacity of Australian vegetation to assimilate atmospheric CO2 under given precipitation.

Prevalence of intestinal trichomonads in captive non-human primates in China.

Trichomonads are protozoan symbionts with the capacity to infect vertebrates including humans and non-human primates (NHPs), sometimes with pathogenic effects. However, their diversity and prevalence in NHPs in China are poorly understood. A total of 533 fecal samples were collected from captive NHPs in Yunnan Province, China, of which 461 samples from Macaca fascicularis and 72 from Macaca mulatta. Trichomonadidae species were identified using PCR amplification of the ITS-1/5.8S/ITS-2 sequences. The overall prevalence of trichomonads in NHPs was determined to be 11.4% (61/533), with gender, diarrhea, and region identified as potential risk factors for the infections. Sequence alignment and phylogenetic analysis identified three species of trichomonads, i.e., Trichomitopsis minor (n = 45), Pentatrichomonas hominis (n = 11), and Tetratrichomonas sp. (n = 5). To the best of our knowledge, this is the first study to report Trichomitopsis minor infection in NHPs in China. Of note, Pentatrichomonas hominis is generally recognized as a parasitic organism affecting humans. Collectively, our results suggest that NHPs are potential sources of zoonotic trichomonad infections, highlighting the importance of surveillance and control measures to protect human and animal populations.

Title: Prévalence des Trichomonadidae intestinaux chez les primates non humains captifs en Chine. Abstract: Les Trichomonadidae sont des symbiotes protozoaires capables d'infecter les vertébrés, notamment les humains et les primates non humains (PNH), parfois avec des effets pathogènes. Cependant, leur diversité et leur prévalence chez les PNH en Chine sont mal comprises. Au total, 533 échantillons fécaux ont été collectés sur des PNH captifs dans la province du Yunnan, en Chine, dont 461 échantillons de Macaca fascicularis et 72 de Macaca mulatta. Les espèces de Trichomonadidae ont été identifiées par amplification PCR des séquences ITS-1/5.8S/ITS-2. La prévalence globale des Trichomonadidae dans les PNH a été déterminée à 11,4 % (61 / 533) et le sexe, la diarrhée et la région ont été identifiés comme facteurs de risque potentiels d'infection. L'alignement des séquences et l'analyse phylogénétique ont identifié trois espèces de Trichomonadidae, à savoir Trichomitopsis minor (n = 45), Pentatrichomonas hominis (n = 11) et Tetratrichomonas sp. (n = 5). À notre connaissance, il s'agit de la première étude à signaler une infection par Trichomitopsis minor chez les PNH en Chine. Il convient de noter que Pentatrichomonas hominis est généralement reconnu comme un organisme parasitaire affectant les humains. Collectivement, nos résultats suggèrent que les PNH sont des sources potentielles d'infections zoonotiques à Trichomonadidae, soulignant l'importance des mesures de surveillance et de contrôle pour protéger les populations humaines et animales.

Interpreting pH-Dependent Differential UV/VIS Absorbance Spectra to Characterize Carboxylic and Phenolic Chromophores in Natural Organic Matter.

Natural organic matter (NOM) is critical for the biogeochemical cycles of energy and many elements in terrestrial and aquatic ecosystems, and protonation-active functional groups in NOM molecules, notably carboxylic and phenolic groups often mediate these critical environmental functions. Molecular heterogeneity, polydispersity and dynamic behavior of NOM complicate achieving an unambiguous description of its molecular properties and reactivity. This study demonstrates that differential ultraviolet-visible (UV/VIS) absorbance spectra (DAS) of NOM acquired at varying pH values exhibit several distinct features associated with the deprotonation of NOM molecules, independent of the environmental provenance of NOM (e.g., surface water, seawater, sediment, and wastewater). The protonation-active functionalities that contribute to the Gaussian distribution bands present in the DAS were identified here by comparing characteristic properties of the bands with the stoichiometries of NOM molecules ascertained by Ultrahigh-Resolution Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). The protonation-active individual chromophores universally present in NOM molecules were identified by a genetic molecular network analysis. The observed DAS features were closely modeled via superimposing DAS spectra of 51 individual protonation-active chromophores. Molecular orbital theory was applied to further interpret the deprotonation of these chromophores, their molecular structure, electron distribution, and electron transitions measured using DAS. The high sensitivity and easy implementation of the DAS approach allows using it as a powerful tool to quantify the molecular properties and reactivity of NOM at environmental concentrations.

First-principles study on the high-pressure physical properties of orthocarbonate Ca2CO4.

Orthorhombic Ca2CO4 is a recently discovered orthocarbonate whose high-pressure physical properties are critical for understanding the deep carbon cycle. Here, we study the structure, elastic and seismic properties of Ca2CO4-Pnma at 20-140 GPa using first-principles calculations, and compare them with the results of CaCO3 polymorphs. The results show that the structural parameters of Ca2CO4-Pnma are in good agreement with the experimental results. It could be the potential host of carbon in the Earth's mantle subduction slab, and its low wave velocity and small anisotropy may be the reason why it cannot be detected in seismic observation. The thermodynamic properties of Ca2CO4-Pnma at high temperature and high pressure are obtained using the quasi-harmonic approximation method. This study is helpful in understanding the behavior of Ca-carbonate in the Earth's lower mantle conditions.

Subtyping of Nonhuman Primate-Adapted Cryptosporidium hominis in Macaca Fascicularis and Macaca mulatta in Yunnan Province, Southwestern China.

Background: Cryptosporidium spp. are a type of protozoan parasite responsible for causing diarrheal illness worldwide. They infect a broad range of vertebrate hosts, including both non-human primates (NHPs) and humans. In fact, zoonotic transmission of cryptosporidiosis from NHPs to humans is frequently facilitated by direct contact between the two groups. However, there is a need to enhance the information available on the subtyping of Cryptosporidium spp. in NHPs in the Yunnan province of China. Materials and Methods: Thus, the study investigated the molecular prevalence and species of Cryptosporidium spp. from 392 stool samples of Macaca fascicularis (n = 335) and Macaca mulatta (n = 57) by using nested PCR targeting the large subunit of nuclear ribosomal RNA (LSU) gene. Of the 392 samples, 42 (10.71%) were tested Cryptosporidium-positive. Results: All the samples were identified as Cryptosporidium hominis. Further, the statistical analysis revealed that age is a risk factor for the infection of C. hominis. The probability of detecting C. hominis was found to be higher (odds ratio = 6.23, 95% confidence interval 1.73-22.38) in NHPs aged between 2 and 3 years, as compared with those younger than 2 years. Sequence analysis of the 60 kDa glycoprotein (gp60) identified six (IbA9 n = 4, IiA17 n = 5, InA23 n = 1, InA24 n = 2, InA25 n = 3, and InA26 n = 18) C. hominis subtypes with "TCA" repeats. Among these subtypes, it has been previously reported that the Ib family subtypes are also capable of infecting humans. Conclusion: The findings of this study highlight the genetic diversity of C. hominis infection among M. fascicularis and M. mulatta in Yunnan province. Further, the results confirm that both these NHPs are susceptible to C. hominis infection, posing a potential threat to humans.

Interaction between tissue-dwelling helminth and the gut microbiota drives mucosal immunoregulation.

Tissue-dwelling helminths affect billions of people around the world. They are potent manipulators of the host immune system, prominently by promoting regulatory T cells (Tregs) and are generally associated with a modified host gut microbiome. However, the role of the gut microbiota in the immunomodulatory processes for these non-intestinal parasites is still unclear. In the present study, we used an extra-intestinal cestode helminth model-larval Echinococcus multilocularis to explore the tripartite partnership (host-helminth-bacteria) in the context of regulating colonic Tregs in Balb/c mice. We showed that larval E. multilocularis infection in the peritoneal cavity attenuated colitis in Balb/c mice and induced a significant expansion of colonic Foxp3+ Treg populations. Fecal microbiota depletion and transplantation experiments showed that the gut microbiota contributed to increasing Tregs after the helminth infection. Shotgun metagenomic and metabolic analyses revealed that the gut microbiome structure after infection was significantly shifted with a remarkable increase of Lactobacillus reuteri and that the microbial metabolic capability was reprogrammed to produce more Treg cell regulator-short-chain fatty acids in feces. Furthermore, we also prove that the L. reuteri strain elevated in infected mice was sufficient to promote the colonic Treg frequency and its growth was potentially associated with T cell-dependent immunity in larval E. multilocularis infection. Collectively, these findings indicate that the extraintestinal helminth drives expansions of host colonic Tregs through the gut microbes. This study suggests that the gut microbiome serves as a critical component of anti-inflammation effects even for a therapy based on an extraintestinal helminth.

Cloud platform to improve efficiency and coverage of asynchronous multidisciplinary team meetings for patients with digestive tract cancer.

Background: Multidisciplinary team (MDT) meetings are the gold standard of cancer treatment. However, the limited participation of multiple medical experts and the low frequency of MDT meetings reduce the efficiency and coverage rate of MDTs. Herein, we retrospectively report the results of an asynchronous MDT based on a cloud platform (cMDT) to improve the efficiency and coverage rate of MDT meetings for digestive tract cancer. Methods: The participants and cMDT processes associated with digestive tract cancer were discussed using a cloud platform. Software programming and cMDT test runs were subsequently conducted to further improve the software and processing. cMDT for digestive tract cancer was officially launched in June 2019. The doctor response duration, cMDT time, MDT coverage rate, National Comprehensive Cancer Network guidelines compliance rate for patients with stage III rectal cancer, and uniformity rate of medical experts' opinions were collected. Results: The final cMDT software and processes used were determined. Among the 7462 digestive tract cancer patients, 3143 (control group) were diagnosed between March 2016 and February 2019, and 4319 (cMDT group) were diagnosed between June 2019 and May 2022. The average number of doctors participating in each cMDT was 3.26 ± 0.88. The average doctor response time was 27.21 ± 20.40 hours, and the average duration of cMDT was 7.68 ± 1.47 min. The coverage rates were 47.85% (1504/3143) and 79.99% (3455/4319) in the control and cMDT groups, respectively. The National Comprehensive Cancer Network guidelines compliance rates for stage III rectal cancer patients were 68.42% and 90.55% in the control and cMDT groups, respectively. The uniformity rate of medical experts' opinions was 89.75% (3101/3455), and 8.97% (310/3455) of patients needed online discussion through WeChat; only 1.28% (44/3455) of patients needed face-to-face discussion with the cMDT group members. Conclusion: A cMDT can increase the coverage rate of MDTs and the compliance rate with National Comprehensive Cancer Network guidelines for stage III rectal cancer. The uniformity rate of the medical experts' opinions was high in the cMDT group, and it reduced contact between medical experts during the COVID-19 pandemic.

Prediction of the electronic structure of single-walled GeS nanotubes.

The structure and electronic properties of puckered GeS nanotubes have been investigated using first-principles density functional theory calculation. Our results show that both the armchair and zigzag GeS nanotubes are semiconductor materials with an adjustable band gap. The band gap increases gradually with increasing the tube diameter, and slowly converges to the monolayer limit. On the application of strain, the GeS nanotubes provide interesting strain-induced band gap variation. When the compressive strain reached 20%, zigzag GeS nanotubes are completely transformed into armchair GeS nanotubes. In addition, the elastic properties of the relatively stable armchair GeS nanotubes have been studied, the Young's modulus of the armchair (11, 11), (13, 13) and (15, 15) nanotubes were calculated to be 227.488 GPa, 211.888 GPa and 213.920 GPa, respectively. Our work confirms that compared with carbon nanotubes, two-dimensional materials with a puckered structure are easier to realize phase transition by stress.

Expansion of Opportunistic Enteric Fungal Pathogens and Occurrence of Gut Inflammation in Human Liver Echinococcosis.

Increasing evidence shows that the gut fungal mycobiota is implicated in human disease. However, its relationship with chronic helminth infections, which cause immunosuppression and affect over 1 billion people worldwide, remains unexplored. In this study, we investigated the gut mycobiome and its associations with gut homeostasis in a severe helminth disease worldwide: liver echinococcosis. Fecal samples from 63 patients and 42 healthy controls were collected to characterize the fungal signatures using ITS1 sequencing, QIIME pipeline, and machine learning analysis. The levels of fecal calprotectin and serological anti-Saccharomyces cerevisiae antibodies (ASCA) in these subjects were experimentally measured. We found that fungal microbiota was significantly skewed in disease, with an overrepresentation of Aspergillus, Candida, Geotrichum, Kazachstania, and Penicillium and a decrease of Fusarium. Machine learning analysis revealed that the altered fungal features could efficiently predict infection with high sensitivity and specificity (area under the curve [AUC] = 0.93). The dysbiosis was characterized by expansions of multiple opportunistic pathogens (Aspergillus spp. and Candida spp.). Clinical association analysis revealed that host immunity might link to the expansions of the invasive fungi. Accompanying the opportunistic pathogen expansion, the levels of fungi-associated fecal calprotectin and serological ASCA in the patients were elevated, suggesting that gut inflammation and microbiota translocation occurred in this generally assumed extraintestinal disease. This study highlights enteric fungal pathogen expansions and increased levels of markers for fungi-associated mucosal inflammation and intestinal permeability as hallmarks of liver echinococcosis. IMPORTANCE Helminth infection affects over 1 billion people worldwide. However, its relationship with the gut mycobiome remains unknown. Among the most prevalent helminth diseases, human hydatid disease (echinococcosis) is highlighted as one of the most important (second/third for alveolar/cystic echinococcosis) foodborne parasitic diseases at the global level. Herein, we investigated the mycobiome and gut homeostasis (i.e., inflammation and permeability) in human echinococcosis. Our results revealed that fungal dysbiosis with an expansion of opportunistic pathogens and increased levels of fecal calprotectin and serum ASCA are hallmarks of human liver echinococcosis. Host immunity is associated with enteric fungal expansions. These findings suggest that an extraintestinal helminth infection is able to alter gut fungal microbiota and impair gut homeostasis, which resembles concomitant gut symptoms in inflammatory gut-related diseases (e.g., AIDS). In clinical practice, physicians need to take cautious medical consideration of gut health for nonintestinal helminth diseases.

HIV protease inhibitor nelfinavir is a potent drug candidate against echinococcosis by targeting Ddi1-like protein.

BACKGROUND: Alveolar echinococcosis (AE), which is caused by larval Echinococcus multilocularis, is one of the world's most dangerous neglected diseases. Currently, no fully effective treatments are available to cure this disease. METHODS: In vitro protoscolicidal assay along with in vivo murine models was applied in repurposing drugs against AE. Genome-wide identification and homology-based modeling were used for predicting drug targets. RNAi, enzyme assay, and RNA-Seq analyses were utilized for investigating the roles in parasite survival and validations for the drug target. FINDINGS: We identified nelfinavir as the most effective HIV protease inhibitor against larval E. multilocularis. Once-daily oral administration of nelfinavir for 28 days resulted in a remarkable reduction in parasite infection in either immune-competent or immunocompromised mice. E. multilocularis DNA damage-inducible 1 protein (EmuDdi1) is predicted as a target candidate for nelfinavir. We proved that EmuDdi1 is essential for parasite survival and protein excretion and acts as a functionally active protease for this helminth. We found nelfinavir is able to inhibit the proteolytic activity of recombinant EmuDdi1 and block the EmuDdi1-related pathways for protein export. With other evidence of drug efficacy comparison, our results suggest that inhibition of EmuDdi1 is a mechanism by which this HIV proteinase inhibitor mediates its antiparasitic action on echinococcosis. INTERPRETATION: This study demonstrates that nelfinavir is a promising candidate for treating echinococcosis. This drug repurposing study proves that the widely prescribed drug for AIDS treatment is potent in combating E. multilocularis infection and thus provides valuable insights into the development of single-drug therapy for highly prevalent co-infection between HIV and helminth diseases. FUNDING: This work was supported by the National Natural Science Foundation of China (31802179), the Natural Science Foundation of Gansu Province, China (No. 21JR7RA027), and the State Key Laboratory of Veterinary Etiological Biology (No. SKLVEB2021YQRC01).

A chromosome-level genome assembly for the rabbit tapeworm Taenia pisiformis.

Taenia pisiformis is one of the most widespread gastrointestinal parasites and its larvae (cysticercosis) causes significant economic loss to rabbit industry. No efficient drug is available for this disease to date. To better understand its genomics, we assembled a 211-Mb high quality genome of T. pisiformis at chromosome level with a scaffold N50 size of 20 Mbp. Totally, 12,097 protein-coding genes was predicted from the genome. Genome-level phylogenetic analysis confirmed the taxonomic affiliations with other tapeworms and revealed that T. pisiformis diverged from its closely related relative T. hydatigena âˆ¼ 14.6 Mya. Comparative genomic analyses revealed that the T. pisiformis genome was characterized by adaptive features of strong positive selection signals from carbohydrate/lipid metabolism and body surface integrity, and of expanded gene families related to metabolism of amino acids and lipids. The high-quality genome of T. pisiformis constitutes a resource for the comparative genomics and for further applications in general parasitology.

Echinococcosis Is Associated with the Increased Prevalence of Intestinal Blastocystis Infection in Tibetans and Host Susceptibility to the Blastocystis in Mice.

Blastocystis is a common human intestinal protozoan parasite. Little is known about its prevalence in echinococcosis. This study tested whether Echinococcus multilocularis infection would increase host susceptibility to Blastocystis. A total of 114 fecal samples (68 hydatid disease patients and 46 healthy people) were collected from Tibetans in the Qinghai province in China. The presence of Blastocystis was identified by sequencing of the small subunit (SSU) rRNA gene. Balb/c mice were co-infected with Blastocystis and E. multilocularis and tested for host susceptibility to Blastocystis. The overall Blastocystis prevalence was 12.3%; 16.2% in the patients and 4.4% in healthy people (p < 0.05). Sequence analysis identified three known Blastocystis genotypes, including ST1, ST2, and ST3, and one unknown genotype. Experimental dual infection significantly reduced mouse survival rate (20%), induced more severe signs, and increased intestinal damages with a higher intestinal colonization level of Blastocystis. The mouse model showed that E. multilocularis infection increases host susceptibility to Blastocystis. Our study shows a significantly higher prevalence of Blastocystis in patients with liver echinococcosis and reveals that non-intestinal E. multilocularis infection increases host susceptibility to the Blastocystis. Our results highlight that E. multilocularis infection is associated with Blastocystis. These findings remind us that more attention should be paid to the gut health of the patients with a helminth infection during clinical patient care.

The genome of the thin-necked bladder worm Taenia hydatigena reveals evolutionary strategies for helminth survival.

Taenia hydatigena is a widespread gastrointestinal helminth that causes significant health problems in livestock industry. This parasite can survive in a remarkably wide range of intermediate hosts and affects the transmission dynamics of zoonotic parasites. T. hydatigena is therefore of particular interest to researchers interested in studying zoonotic diseases and the evolutionary strategies of parasites. Herein we report a high-quality draft genome for this tapeworm, characterized by some hallmarks (e.g., expanded genome size, wide integrations of viral-like sequences and extensive alternative splicing during development), and specialized adaptations related to its parasitic fitness (e.g., adaptive evolutions for teguments and lipid metabolism). Importantly, in contrast with the evolutionarily close trematodes, which achieve gene diversification associated with immunosuppression by gene family expansions, in T. hydatigena and other cestodes, this is accomplished by alternative splicing and gene loss. This indicates that these two classes have evolved different mechanisms for survival. In addition, molecular targets for diagnosis and intervention were identified to facilitate the development of control interventions. Overall, this work uncovers new strategies by which helminths evolved to interact with their hosts.

Knowledge about Human Papillomavirus and Cervical Cancer Prevention among Intern Nurses.

OBJECTIVE: Intern nurses will play an important role in the use of vaccination to prevent cervical cancer. This study assesses the knowledge about human papillomavirus (HPV) infection and cervical cancer prevention among intern nurses. METHODS: We developed a questionnaire to investigate intern nurses' knowledge about HPV infection and cervical cancer prevention. Participants included 323 intern nurses from eight schools. RESULTS: The effective response rate was 79.8%. Some (7.0%) knew that early-stage cervical cancer is commonly asymptomatic. Only 9.7% knew that infection is generally asymptomatic and 20.5% knew that vaccination has no major side effects. There were differences in gender, age, school type, and place of residence for several questions. CONCLUSIONS: This study indicates a low level of knowledge about HPV infection and cervical cancer prevention among intern nurses. Our findings highlight the need for more education in this topic to increase the knowledge of intern nurses.

Transcriptome profiling of Cysticercus Pisiformis provides insight into responses to host bile acids.

Bile acids in host intestine activate larvae of tapeworms and facilitate its invasion. However, the mechanism underlying this process is poorly understood. In order to better understand responses of tapeworms to host biles, we used RNA-Seq profiling method to study the transcriptomes of Cysticercus Pisiformis (larvae of Taenia Pisiformis) after host bile acid treatment. A total of 338.32 million high-quality clean reads were obtained by Illumina Hiseq platform. Totally, 62,009 unigenes were assembled, 38,382 of which were successfully annotated to known databases. A total of 9324 unigenes were identified as differentially expressed genes (DEGs), of which 5380 and 3944 genes were up- and down-regulated in the group treated with bile acids, respectively. Gene Ontology analysis revealed that biosynthesis and energy metabolism potential were significantly strengthened after host bile treatment in C. pisiformis. Similarly, KEGG pathway analysis revealed an enrichment of pathways related to lipid metabolism and carbohydrate metabolism. Among them, 'AMPK signaling pathway' which is critical in balancing cellular energy, was significantly enriched after bile acids activation. In addition, pathways of 'Fatty acid biosynthesis', 'Fatty acid elongation', 'Starch and sucrose metabolism', and 'glycolysis gluconeogenesis' were also significantly changed after bile acid treatment. qRT-PCR analysis confirmed the differential abundances of some key genes in these pathways. Our data suggest that host bile acids remarkably promote the pathways of energy metabolism of this parasite and regulate the genes involved in balancing lipid metabolism and carbohydrate metabolism. These findings provide new insights on the lifecycle of Taenia parasites.

Machine-Learning Assisted Screening of Energetic Materials.

In this work, machine learning (ML), materials informatics (MI), and thermochemical data are combined to screen potential candidates of energetic materials. To directly characterize energetic performance, the heat of explosion ΔHe is used as the target property. The critical descriptors of cohesive energy, averaged over all constituent elements and the oxygen balance, are found by forward stepwise selection from a large number of possible descriptors. With them and a theoretically labeled ΔHe training data set, a satisfactory surrogate ML model is trained. The ML model is applied to large databases ICSD and PubChem to predict ΔHe. At the gross-level filtering by the ML model, 2732 molecular candidates based on carbon, hydrogen, nitrogen, and oxygen (CHNO) with high ΔHe values are predicted. Afterward, a fine-level thermochemical screening is carried out on the 2732 materials, resulting in 262 candidates with TNT equivalent power index Pe(TNT) greater than 1.5. Raising Pe(TNT) further to larger than 1.8, 29 potential candidates are found from the 2732 materials, all are new to the current reservoir of well-known energetic materials.

Effects of Inoculation on the Pearlitic Gray Cast Iron with High Thermal Conductivity and Tensile Strength.

With the aim of improving the thermal conductivity and tensile strength of pearlitic gray cast iron, the influence of inoculation on structure and properties was experimentally investigated. Three group of irons with similar compositions were inoculated by Zr-FeSi, Sr-FeSi, and SiC inoculants, respectively. The metallographic analysis was used to measure the maximum graphite length, primary dendrites amount and eutectic colonies counts. For a certain carbon equivalent, it was confirmed that the thermal conductivity of pearlitic gray cast iron has a direct correlation with the maximum graphite length while the tensile strength was influenced mainly by the primary dendrites amount. The optimal structure and highest thermal conductivity and tensile strength were obtained by Sr-FeSi inoculant. MnS particles act a pivotal part in modifying the structure of gray cast iron. It was found that providing nucleation sites both for graphite and primary austenite is important to promote the thermal conductivity and strength. However, excessive nuclei (MnS particles) results in shorter graphite flakes and thus the depressive growth of primary dendrites.

Luminescent properties of Eu-doped magnetic Na3FeF6.

Sodium iron fluoride (Na3FeF6) is a colorless ferromagnetic fluoride with a monoclinic crystal structure (space group P21/c), and it is expected to be an ideal platform for exploring magneto-optical interactions. In the present work, Eu3+ doped Na3FeF6 micro-powders were synthesized by a hydrothermal method, and the structures were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties were examined using UV-Vis spectra and fluorescence spectra, and the results show that the emission spectra can be finely tuned by the hydrothermal reaction temperature and doping concentration of Eu ions. We found that Na3FeF6 doped with 5% Eu3+ synthesized at 196 °C exhibited the optimal red emission under excitation at 395 nm. The magnetization of Na3FeF6:5% Eu3+ decreased rapidly from about 7.85 emu g-1 at 5 K to 0.4 emu g-1 at 60 K, then slowly decreased with temperature increase from 60 K to 300 K. This Eu3+ doped Na3FeF6 powder is expected to find potential applications in the field of magneto-optical modulation and relevant devices.

Unexpected coordination number and phase diagram of niobium diselenide under compression.

We discovered several new energetically competitive structures of NbSe2 using the multi-algorithm collaborative (MAC) crystal structure prediction algorithm combined with the density functional theory. It was found that the coordination number of Nb in NbSe2 is increased from 6 to 7, and then to 8 with increasing pressure. Furthermore, it was unexpected that an Se atom would be squeezed to the center of a cage formed by 12 other Se atoms and then have 12-fold coordination when the pressure was increased to 130.4 GPa. The 12-coordination metalloid atom has never been discovered in other transition metal dichalcogenides. The new C2/m, I4/mmm, and P4/mmm NbSe2 were verified to be stable under both dynamically and mechanically stabile conditions. It is especially noteworthy that the new C2/m-NbSe2 was predicted to be potentially synthesized at high pressure and recovered under ambient conditions. A detailed high-pressure and high-temperature phase diagram was constructed based on the quasi-harmonic approximation up to 200 GPa, and the synthesis conditions of different new NbSe2 materials were also analyzed. All the discoveries in this study will guide the future synthesis of new NbSe2 materials at specific pressure and under temperature conditions and also help to further understand other transition metal dichalcogenides.

Phase diagram and physical properties of iridium tetraboride from first principles.

Using both the swarm-intelligence-based CALYPSO method and the multi-algorithm-collaborative (MAC) algorithm for crystal structure prediction, three unexpected new phases (P63/mmc, C2/m and Cmca) of IrB4 are predicted. The P63/mmc phase is the ground-state structure under ambient conditions, while C2/m and Cmca phases form at high pressure. The phase stabilities, mechanical and electronic properties of the three new phases of IrB4 are investigated systematically. We firstly found that pressure stimulates IrB4 to undergo phase transition twice, P63/mmc phase to C2/m phase at 29 GPa and C2/m phase to Cmca at 99 GPa. Strikingly, the three phases are both dynamically and mechanically stable under ambient conditions. The high bulk and shear moduli and low Poisson's ratio for the three phases in IrB4 make IrB4 a promising low-compressible material. Detailed analysis of density of states and electronic local functions reveals that the covalent bonding of Ir-B and B-B is responsible for their structural stability and high hardness. Finally, the high-pressure and high-temperature phase diagram of IrB4 is established, where the triple point of phase transition for P63/mmc-, C2/m- and Cmca-IrB4 is at 60 GPa and 1930 K.