To evaluate pore structures of the Bakken Shale, which is one of the most important factors that affect petrophysical properties, high-pressure mercury intrusion was employed in this study. Pore structures such as pore-throat size, pore-throat ratio, and fractal attributes are investigated in this major shale play. Pore-throat size from 3.6 to 200 um is widely distributed in these shale samples. Accordingly, pore-throat size distributions demonstrate the multimodal behavior within the samples. The whole pore-throat network can be divided into four clusters: one set of large pores, two transitional/intermediate pore groups, and one set of smaller pores. The fractal analysis revealed that fractal dimensions decrease as the pore-throat size decreases. The multifractal analysis demonstrated that as the maturity of the shale samples increases, pore-throat size distributions would become more uniform and pore structures tend to become more homogeneous. The results are compared to our previous results obtained from nitrogen gas adsorption for further verifications of fractal behavior. Finally, although fractal analysis of mercury intrusion and nitrogen gas adsorption were comparable, the results of multifractal analysis from these two methods were not identical.
The natural draft dry cooling tower (NDDCT) has been increasingly used in power generation for its merits of excellent water-saving, high energy saving, simple maintenance and long life service. To study the performance of a newly installed 660 MW NDDCT under crosswind condition, a model with scale of 1:200 was built according to the scaling law of geometric similarity. The experiments were set up in self-similar region with high Reynolds to meet momentum similarity, while meeting the scaling law of Froude and Euler numbers. A first order law radiator resistance model is also proposed and verified by a systematic test. The exponent law profile of wind velocity above the ground was built and verified by experimental data. On the ground of a constant heating rate bases, the flow field inside the NDDCT and the ventilation rate were investigated at the crosswind range of 0–20 m/s.
Despite their crucial roles in health and climate concerns, the gas-particle partitioning of carbonyl compounds is poorly characterized in the ambient atmosphere. In this study, we investigate their partitioning by simultaneously measuring six carbonyl compounds (formaldehyde, acetaldehyde, acetone, propionaldehyde, glyoxal, and methylglyoxal) in gas and particle phase at an urban site in Beijing. The field-derived partitioning coefficients (Kpf) are in the range of 10−5−10−3 m3 µg−1, and corresponding effective Henry’s law coefficients (KHf) should be 107–109 M atm−1. The Pankow’s absorptive partitioning theory and the Henry’s law both significantly underestimate concentrations of particle-phase carbonyl compounds (105–106 times and >103 times, respectively). The observed “salting in” effects only partially explain the enhanced partitioning to particles, approximately one order of magnitude. The measured Kpf values are higher at low relative humidity and the overall effective vapor pressure of these carbonyl species are lower than their hydrates, indicating that carbonyl oligomers potentially formed in highly concentrated particle phase. The reaction kinetics of oligomer formation should be included if applying the Henry’s law to low-to-moderate RH and the high partitioning coefficients observed need further field and laboratory studies. These findings provide deeper insights into the formation of carbonyl secondary organic aerosols in the ambient atmosphere.
A gate-recessed normally OFF GaN metal-oxide-semiconductor high-electron-mobility transistor on silicon substrate has been fabricated using a self-terminated, plasma-free oxidation and wet etching process with pre-recess low-pressure chemical vapor deposition (LPCVD) Si3N4 passivation layer. The LPCVD Si3N4 serves the dual role of gate-recess mask and passivation layer. Unlike conventional oxidation etching process using Si3N4 as post gate-recess passivation, the gate channel region was prevented from additional plasma bombardment during the gate window re-opening. As a result, a high-effective channel mobility of 843 cm(2)/V . s, and low-channel resistance of 0.89 Omega . mm are achieved for a normally OFF channel with L-G = 1.5 mu m. For 3 mu m L-GD, the fabricated devices exhibit a threshold voltage (Vth) of 1.35 V, a maximum drain current of similar to 500 mA/mm, a high ON/OFF current ratio of similar to 1010, and 560-V OFF-state breakdown voltage together with a low-forward gate leakage current of similar to 10-7 mA/mm up to 10 V. A high Baliga's figure of merit of 1.26 GW/cm(2) is achieved in devices with 10-mu m gate-drain distance.
A prototype of a laser driven proton accelerator is built at Peking University. Protons exceeding 10 MeV are accelerated from micrometer-thick aluminum targets irradiated by tightly focused laser pulse with 1.8 J energy and 30 fs duration. The beam energy spectrum and charge distribution are measured by a Thomson parabola spectrometer and radiochromic film stacks. The sensitivity of proton cut-off energy to the focusing of the laser beam, the pulse duration, and the foil thickness are systematically investigated in the experiments. Stable proton beams have been produced with an optimized parameter set, providing a cornerstone for the future applications of laser accelerated protons.
A scheme to radiate a highly collimated gamma-ray pulse is proposed through the interaction between an ultra-intense laser pulse and a narrow tube target. The gamma-ray pulse, with high conversion efficiency, can be generated as a result of electron acceleration in a longitudinal electric field. In a Particle-inCell simulation with a 10-PW laser, 18% of the laser energy is transferred into the forward gamma-ray in a divergence angle less than 3 degrees. It is also found that such a highly collimated gamma-ray pulse can be produced with a large range of tube diameters and laser intensities. This scheme could be realized in experiment with the coming 10-PW class lasers in the near future. Published by AIP Publishing.
C-reactive protein (CRP) is a sensitive biomarker of chronic low-grade inflammation and is associated with multiple complex diseases. The genetic determinants of chronic inflammation remain largely unknown, and the causal role of CRP in several clinical outcomes is debated. We performed two genome-wide association studies (GWASs), on HapMap and 1000 Genomes imputed data, of circulating amounts of CRP by using data from 88 studies comprising 204,402 European individuals. Additionally, we performed in silico functional analyses and Mendelian randomization analyses with several clinical outcomes. The GWAS meta-analyses of CRP revealed 58 distinct genetic loci (p < 5 x 10(-8)). After adjustment for body mass index in the regression analysis, the associations at all except three loci remained. The lead variants at the distinct loci explained up to 7.0% of the variance in circulating amounts of CRP. We identified 66 gene sets that were organized in two substantially correlated clusters, one mainly composed of immune pathways and the other characterized by metabolic pathways in the liver. Mendelian randomization analyses revealed a causal protective effect of CRP on schizophrenia and a risk-increasing effect on bipolar disorder. Our findings provide further insights into the biology of inflammation and could lead to interventions for treating inflammation and its clinical consequences.
Macronutrient intake, the proportion of calories consumed from carbohydrate, fat, and protein, is an important risk factor for metabolic diseases with significant familial aggregation. Previous studies have identified two genetic loci for macronutrient intake, but incomplete coverage of genetic variation and modest sample sizes have hindered the discovery of additional loci. Here, we expanded the genetic landscape of macronutrient intake, identifying 12 suggestively significant loci (P < 1 x 10(-6)) associated with intake of any macronutrient in 91,114 European ancestry participants. Four loci replicated and reached genome-wide significance in a combined meta-analysis including 123,659 European descent participants, unraveling two novel loci; a common variant in RARB locus for carbohydrate intake and a rare variant in DRAM1 locus for protein intake, and corroborating earlier FGF21 and FTO findings. In additional analysis of 144,770 participants from the UK Biobank, all identified associations from the two-stage analysis were confirmed except for DRAM1. Identified loci might have implications in brain and adipose tissue biology and have clinical impact in obesity-related phenotypes. Our findings provide new insight into biological functions related to macronutrient intake.
Bacteria capable of simultaneous aerobic denitrification and phosphorus removal (SADPR) are promising for the establishment of novel one-stage wastewater treatment systems. Nevertheless, insights into the metabolic potential of SADPR-related bacteria are limited. Here, comprehensive metabolic models of two efficient SADPR bacteria, Achromobacter sp. GAD3 and Agrobacterium sp. LAD9, were obtained for the first time by high-throughput genome sequencing. With succinate as the preferred carbon source, both strains employed a complete TCA cycle as the major carbon metabolism for potentials of various organic acids and complex carbon oxidation. Complete and truncated aerobic denitrification routes were confirmed in GAD3 and LAD9, respectively, facilitated by all the major components of the electron transfer chain via oxidative phosphorylation. Comparative genome analysis revealed distinctive ecological niches involved in denitrification among different phylogenetic clades within Achromobacter and Agrobacterium. Excellent phosphorus removal capacities were contributed by inorganic phosphate uptake, polyphosphate synthesis and phosphonate metabolism. Additionally, the physiology of GAD3/LAD9 is different from that displayed by most available polyphosphate accumulating organisms, and reveals both strains to be more versatile, carrying out potentials for diverse organics degradation and outstanding SADPR capacity within a single organism. The functional exploration of SADPR bacteria broadens their significant prospects for application in concurrent aerobic carbon and nutrient removal.
Atmospheric new particle formation (NPF) is an important phenomenon in terms of global particle number concentrations. Here we investigated the frequency of NPF, formation rates of 10 nm particles, and growth rates in the size range of 10-25 nm using at least 1 year of aerosol number size-distribution observations at 36 different locations around the world. The majority of these measurement sites are in the Northern Hemisphere. We found that the NPF frequency has a strong seasonal variability. At the measurement sites analyzed in this study, NPF occurs most frequently in March-May (on about 30 % of the days) and least frequently in December-February (about 10 % of the days). The median formation rate of 10 nm particles varies by about 3 orders of magnitude (0.01-10 cm(-3) s(-1)) and the growth rate by about an order of magnitude (1-10 nm h(-1)). The smallest values of both formation and growth rates were observed at polar sites and the largest ones in urban environments or anthropogenically influenced rural sites. The correlation between the NPF event frequency and the particle formation and growth rate was at best moderate among the different measurement sites, as well as among the sites belonging to a certain environmental regime. For a better understanding of atmospheric NPF and its regional importance, we would need more observational data from different urban areas in practically all parts of the world, from additional remote and rural locations in North America, Asia, and most of the Southern Hemisphere (especially Australia), from polar areas, and from at least a few locations over the oceans.