Molybdenite-bearing porphyry deposits are the predominant supplier of molybdenum to industrialized society and one of the main hosts of Mo in the upper continental crust. The Mo isotope compositions (delta Mo-98/95, normalized to NIST3134 equals 0 parts per thousand) of molybdenite show considerable variation (-1.62 to + 2.27 parts per thousand), but the factors controlling this variability remain poorly constrained. This information is critical for underpinning genetic models of porphyry deposits, understanding elemental cycling, and utilizing the delta Mo-98/95 of marine sediments as a paleoredox proxy. Using the well-characterized Qulong porphyry Cu-Mo deposit (Tibet) as an example, here we discuss how rapid cooling, facilitated by mixing hot magmatic fluid with cold meteoric water, can be a controlling factor on efficient mineralization, and then tackle how fluid evolution regulates molybdenum isotope fractionation. Molybdenites, which preferentially partition isotopically light Mo (Rayleigh fractionation), precipitated from a single fluid will develop a heavier delta Mo-98/95 composition over time, and this also creates hetero-geneous delta Mo-98/95 between molybdenite grains. Whereas a fluid undergoing multiple episodes of intensive boiling will gradually lose its isotopically heavy Mo to the vapor phase, molybdenites crystallizing successively from the residual liquid will then have lighter delta Mo-98/95 over time. However, when mineralization efficiency becomes too low, a negligible variation in delta Mo-98/95 of molybdenite is observed. Given that the mineralization efficiency (i.e., the amount of Mo crystallized as molybdenite from the fluid) rarely reaches 100% and molybdenite favors isotopically light Mo, the presence of a residual fluid with isotopically heavy Mo is inevitable. This residual fluid may then become trapped in alteration halos; hence, delta Mo-98/95 has the potential to aid in locating the mineralization center (e.g., lighter delta Mo-98/95 toward the orebody). The residual fluid may also feed surface hydrological systems and eventually impact Mo cycling. Our study highlights that understanding the controls of isotope fractionation is critical to bridge the gap between ore formation and elemental cycling, and that other transition metals (e.g., Cu, Fe, and Zn) may follow similar trajectories.
Understanding how defaults correlate across firms is a persistent concern in risk management. In this paper, we apply covariate-dependent copula models to assess the dynamic nature of credit risk dependence, which we define as “credit risk clustering”. We also study the driving forces of the credit risk clustering in CEC business group in China. Our empirical analysis shows that the credit risk clustering varies over time and exhibits different patterns across firm pairs in a business group. We also investigate the impacts of systematic and idiosyncratic factors on credit risk clustering. We find that the impacts of the money supply and the short-term interest rates are positive, whereas the impacts of exchange rates are negative. The roles of the CPI on credit risk clustering are ambiguous. Idiosyncratic factors are vital for predicting credit risk clustering. From a policy perspective, our results not only strengthen the results of previous research but also provide a possible approach to model and predict the extreme co-movement of credit risk in business groups with financial indicators.
Summary Contractile injection systems (CISs) are cell-puncturing nanodevices that share ancestry with contractile tail bacteriophages. Photorhabdus virulence cassette (PVC) represents one group of extracellular CISs that are present in both bacteria and archaea. Here, we report the cryo-EM structure of an intact PVC from P. asymbiotica. This over 10-MDa device resembles a simplified T4 phage tail, containing a hexagonal baseplate complex with six fibers and a capped 117-nanometer sheath-tube trunk. One distinct feature of the PVC is the presence of three variants for both tube and sheath proteins, indicating a functional specialization of them during evolution. The terminal hexameric cap docks onto the topmost layer of the inner tube and locks the outer sheath in pre-contraction state with six stretching arms. Our results on the PVC provide a framework for understanding the general mechanism of widespread CISs and pave the way for using them as delivery tools in biological or therapeutic applications.
This work presents a detailed study on the high-frequency performance of 22FDX ® FDSOI for 5G front-end power amplifiers. The following report focuses on the S-parameters and large-signal figure-of-merits such as output power, gain and power-added efficiency for an insightful and correct assessment on the device capability. DC characteristics of the test transistors are firstly investigated to determine the optimum operating point. Small-signal characterization is performed up to 110 GHz using a state-of-the-art mm-Wave measurement setup. An overall MSG/MAG of 16 ± 4 dB is recorded in the frequency range 10 - 80 GHz. On the other hand, large-signal performance on non-50 Ohm impedance environment is evaluated thoroughly through vector-receiver load-pull measurement up to 24 GHz. The measured output power and efficiency indicate that the DUTs perform well in the sub-6 GHz band and even in K-band. The outstanding experimental results emphasize the applicability and suitability of the 22FDX ® FDSOI technology platform for 5G low-power transmitters.
Mental disorders have been associated with various aspects of anthropogenic change to the environment, but the relative effects of different drivers are uncertain. Here we estimate associations between multiple environmental factors (air quality, residential greenness, mean temperature, and temperature variability) and self-assessed mental health scores for over 20,000 Chinese residents. Mental health scores were surveyed in 2010 and 2014, allowing us to link changes in mental health to the changes in environmental variables. Increases in air pollution and temperature variability are associated with higher probabilities of declined mental health. Mental health is statistically unrelated to mean temperature in this study, and the effect of greenness on mental health depends on model settings, suggesting a need for further study. Our findings suggest that the environmental policies to reduce emissions of air pollution or greenhouse gases can improve mental health of the public in China.
CeO2-AgI, synthesized via depositing AgI nanoparticles onto CeO2 nanorods, was utilized for bacterial disinfection and organic contaminant degradation. Escherichia coli (E. coli) and Bisphenol A (BPA) were used as the model bacteria and emerging organic contaminant to test the photocatalytic activity of CeO2-AgI, respectively. Results showed that CeO2-AgI with the optimal AgI content exhibited superior photocatalytic activity over pure CeO2 or AgI for both inactivation of E. coli cells and BPA removal. However, the photocatalytic mechanisms for E. coli inactivation and BPA degradation were different. Specifically, the photo-generated holes (h+), photo-generated electrons (e−) and superoxide radicals (O2−) were the dominated active species for E. coli inactivation, whereas, BPA degradation relied on the generation of O2− and e−. Cell membrane disruption was found to be the main disinfection mechanism. The decomposition of BPA was clarified by detecting the degradation intermediates by LC–MS and DFT calculation. The facile synthesized CeO2-AgI exhibited good photocatalytic stability in four reused cycles and thus could be potentially applied to purify water.
