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BACKGROUND: Except for public health case reports, the incidence of Zika virus (ZIKV), chikungunya virus (CHIKV), and dengue virus (DENV) infection are not available to assess the potential blood transfusion safety threat in Brazil. METHODS: Pools of 6 donation samples (MP6) left over from human immunodeficiency virus, hepatitis B virus, and hepatitis C virus nucleic acid testing were combined to create MP18 pools (3 MP6 pools). Samples were tested using the Grifols triplex ZIKV, CHIKV, and DENV real-time transcription mediated amplification assay to estimate prevalence of RNAemia and incidence, and to compare these results to case reports in São Paulo, Belo Horizonte, Recife, and Rio de Janeiro, from April 2016 through June 2019. RESULTS: ZIKV, CHIKV, and DENV RNAemia were found from donors who donated without overt symptoms of infection that would have led to deferral. The highest RNAemic donation prevalence was 1.2% (95% CI, .8%-1.9%) for DENV in Belo Horizonte in May 2019. Arbovirus infections varied by location and time of year, and were not always aligned with annual arbovirus outbreak seasons in different regions of the country. CONCLUSIONS: Testing donations for arboviruses in Brazil can contribute to public health. Transfusion recipients were likely exposed to ZIKV, CHIKV, and DENV viremic blood components during the study period.

Critical heat flux (CHF) is a crucial safety limit for PWR core design. Accurately predicting CHF in the core rod bundle channel can enhance the economy and safety of the reactor. Currently, the prediction of rod bundle CHF in engineering is mainly based on specific fuel assembly experiments and subchannel code modeling to obtain local parameters that can be used to develop the corresponding CHF correlation. However, the traditional correlation of CHF of the rod bundle cannot be extrapolated effectively due to the rough division of subchannels and the inaccuracy of local parameter calculation of the rod surface. The CHF correlation developed for specific fuel assemblies can only be applied to specific rod bundle geometries. The rod bundle structure of the guide tube requires additional punishment, which does not conform to the local phenomenon hypothesis and cannot achieve real prediction. To predict CHF at different rod bundle geometries, such as new fuel assemblies and new reactors, a mechanism model of CHF of the rod bundle was established based on the high-precision subchannel program developed by Xi’an Jiaotong University. The highprecision subchannel code is further subdivided based on the conventional subchannel division and uses the griddistributed resistance model. Two types of gaps formed by new subchannels are treated separately using the turbulent mixing model. The high-precision subchannel code makes the flow field calculation more accurate. Based on Weisman’s bubble crowding model, a bundle CHF mechanism model was proposed. The turbulent intensity distribution near the bundle wall was obtained using the concept of equivalent tube. The roughness of the bubble layer thickness was considered, and the bubble diameter at the CHF position was solved iteratively. The developed bundle CHF mechanism model was embedded into the high-precision subchannel code and predicted using the bundle CHF experimental database of Xi’an Jiaotong University. The operation condition range of verified data covers the typical operating condition range of PWR, including two rod bundle forms of typical lattice and guide tube lattice, with a total of 601 CHF data points. The assessment results demonstrate that the average ratio of the predicted value to the experimental value is 0.99, and the mean square error is 4.69%, and the deviation has no obvious parameter bias with pressure, mass flux, and critical quality. Furthermore, the model can be well applied to the prediction of CHF of typical lattice and guide tube lattice. The guide tube lattice CHF can be predicted successfully without any modification of the CHF model. This model reveals the essence of the cold wall effect at the mechanism level.

Zika virus (ZIKV) infection of pregnant women can cause fetal microcephaly and other neurologic defects. We describe the development of a non-human primate model to better understand fetal pathogenesis. To reliably induce fetal infection at defined times, four pregnant rhesus macaques are inoculated intravenously and intraamniotically with ZIKV at gestational day (GD) 41, 50, 64, or 90, corresponding to first and second trimester of gestation. The GD41-inoculated animal, experiencing fetal death 7 days later, has high virus levels in fetal and placental tissues, implicating ZIKV as cause of death. The other three fetuses are carried to near term and euthanized; while none display gross microcephaly, all show ZIKV RNA in many tissues, especially in the brain, which exhibits calcifications and reduced neural precursor cells. Given that this model consistently recapitulates neurologic defects of human congenital Zika syndrome, it is highly relevant to unravel determinants of fetal neuropathogenesis and to explore interventions.

In order to study the deformation characteristics of water imbibition of coal body containing gas, a self-designed pressure-bearing gas natural water absorption test platform was used to carry out isobaric natural water absorption experiments in coal gas adsorption equilibrium pressures at 0.5, 1.0, 1.5, 2.0 MPa. The test results showed that: in the gas adsorption stage, with the increase of pressure, the horizontal and vertical deformation of the coal body showed a trend of increase, the vertical strain was about twice as the horizontal strain. In the natural water absorption stage, the transverse and longitudinal deformation of coal body is greater than that of pure gas adsorption under the same gas pressure. The ambient pressure of the experimental system increased slightly, and the maximum value of pressure increase was 0.013 MPa, indicating that the water imbibition was accompanied by gas desorption process. At the stage of gas desorption and water drainage, under different gas pressures, the water content of coal were 0.98%, 1.05%, 1.51%, 2.24%. The volume strain was secondarily related to the initial gas pressure, the residual deformation value of coal body strain was large, and it showed the irreversibility and destructiveness of gas-containing coal deformation after water imbibition.

The vibration characteristics of a composite bridge with constrained layer damping (CLD) were investigated using the wave and finite element method (WFEM), and the effects of the material and geometrical parameters of the CLD on the vibration reduction in the bridge were analyzed. Firstly, a numerical model for the dynamic response of a composite steel–concrete bridge using WFEM. The calculated acceleration of the bridge under the wheel–rail force obtained using this model was in good agreement with that obtained using the conventional finite element method and field measurements. Second, a segment model of the bridge with a CLD was established. The equation of motion based on the WFEM was solved to determine the dynamic response of the bridge induced by running trains. Finally, the effects of the covering area and CLD parameters on the vibration mitigation of steel–concrete bridges were analyzed. The results show that a reduction of 5–10 dB of the acceleration level of steel members in the full frequency range can be achieved by installing the CLD. A lower shear modulus of the viscoelastic core is beneficial for low-frequency vibration reduction in the bridge. However, a higher shear modulus of the damping layer is required for vibration mitigation in the high-frequency range. The vibration reduction in the composite bridge was more sensitive to the thickness of the constraining layer than to that of the damping layer. [ABSTRACT FROM AUTHOR]

Animal models of Zika virus (ZIKV) are needed to better understand tropism and pathogenesis and to test candidate vaccines and therapies to curtail the pandemic. Humans and rhesus macaques possess similar fetal development and placental biology that is not shared between humans and rodents. We inoculated 2 non-pregnant rhesus macaques with a 2015 Brazilian ZIKV strain. Consistent with most human infections, the animals experienced no clinical disease but developed short-lived plasma viremias that cleared as neutralizing antibody developed. In 1 animal, viral RNA (vRNA) could be detected longer in whole blood than in plasma. Despite no major histopathologic changes, many adult tissues contained vRNA 14 days post-infection with highest levels in hemolymphatic tissues. These observations warrant further studies to investigate ZIKV persistence and its potential clinical implications for transmission via blood products or tissue and organ transplants.

[Objective] Global warming may increase the risk of expansion of karst rock desertification (KRD) in Southwest (SW) China, where karst landscapes are widespread, so it is important to reconstruct the evolution of KRD in this region. [Methods] In this study, the regional eco-evolution of the past 4 750 years was reconstructed based on 29 230Th ages and 954 δ13C records collected from stalagmite HD12 in Dark cave, Qianxi county, Guizhou province. [Results and Conclusions]Two significant positive δ13C offsets were found at 4 322-3 526 a B.P.and 803-82 a B.P., indicating deterioration of the ecological environment at those times. A significant positive δ13 C record of the HD12 stalagmite at about 803 a B.P. persisted for about 290 years with an amplitude of 4.2‰, indicating expansion of KRD in the area. The consistent positive δ13C in stalagmites from several caves in SW China during this period suggests that the large-scale population migration and climatic drought after the Jingkang event (823 a B.P.) promoted the expansion of KRD in this region. During 4 322-3 526 a B.P., the positive shift of HD12 stalagmite δ13C values had an amplitude of 4.9‰. The positive shift at 4 322-3 977 a B.P. corresponds to the 4.2 ka event, and for 3 777-3 526 a B.P. it corresponds to the 3.7 ka event. These two periods of drought are also reflected in several stalagmite and lake records in SW China, suggesting that the weakened Asian summer monsoon and reduced precipitation at those times may have caused a large reduction in vegetation cover and severe soil degradation in the region. [ABSTRACT FROM AUTHOR]