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Radiocarbon (14C) has become a unique and powerful tracer in source apportionment of atmospheric carbonaceous particles. In this study, the Asia Pacific Economic Cooperation summit (APEC) held in Beijing in 2014 was used as a demonstration to research the source apportionment of atmosphere PM2.5. We used a 200 kV single stage accelerator mass spectrometer recently completed at China Institute of Atomic Energy (CIAE). The PM2.5 samples related to above case were collected, and the characteristics of radiocarbon in organic carbon (OC) and elemental carbon (EC) in samples were analyzed using the AMS. The results show that the Before-APEC pollution emission mode is different from the During-APEC and After-APEC pollution emission modes. For Before-APEC, During-APEC and After-APEC, the average values of fossil carbon fraction of OC are 0.463, 0.431 and 0.615, respectively, and those of EC are 0.644, 0.561 and 0.687. The fossil source contributions of traffic activities using fossil fuels to OC and EC are 15.8 % and 21.9 %, respectively. The fossil source contributions of industrial activities to OC and EC are 38.0 % and 8.2 %, respectively. It is about 7–10 days that is needed to take to regenerate the PM2.5 pollution caused by human activities.
We assessed inheritance of resistance to sugarcane brown rust (Puccinia melanocephala) in selfing F1 populations of wild sugarcane germplasm Erianthus rockii ‘Yundian 95-19’ and E. rockii ‘Yundian 95-20’. We tested parent and selfing F1 individuals for the brown rust resistance gene, Bru1, that has been shown to confer resistance to brown rust in sugarcane. The Bru1 gene was not detected in E. rockii ‘Yundian 95-19’, E. rockii ‘Yundian 95-20’ or their selfing F1 individuals, and we found there was segregation of resistance in the two selfing F1 populations (segregation ratio: 3:1). The results confirmed resistance in E. rockii ‘Yundian 95-19’ and E. rockii ‘Yundian 95-20’ to sugarcane brown rust is controlled by a novel, single dominant gene.
Existing data on folate status and hepatocellular carcinoma (HCC) prognosis are scarce. We prospectively examined whether serum folate concentrations at diagnosis were associated with liver cancer-specific survival (LCSS) and overall survival (OS) among 982 patients with newly diagnosed, previously untreated HCC, who were enrolled in the Guangdong Liver Cancer Cohort (GLCC) study between September 2013 and February 2017. Serum folate concentrations were measured using chemiluminescent microparticle immunoassay. Cox proportional hazards models were performed to estimate hazard ratios (HR) and 95 % CI by sex-specific quartile of serum folate. Compared with patients in the third quartile of serum folate, patients in the lowest quartile had significantly inferior LCSS (HR = 1·48; 95 % CI 1·05, 2·09) and OS (HR = 1·43; 95 % CI 1·03, 1·99) after adjustment for non-clinical and clinical prognostic factors. The associations were not significantly modified by sex, age at diagnosis, alcohol drinking status and Barcelona Clinic Liver Cancer (BCLC) stage. However, there were statistically significant interactions on both multiplicative and additive scale between serum folate and C-reactive protein (CRP) levels or smoking status and the associations of lower serum folate with worse LCSS and OS were only evident among patients with CRP > 3·0 mg/l or current smokers. An inverse association with LCSS were also observed among patients with liver damage score ≥3. These results suggest that lower serum folate concentrations at diagnosis are independently associated with worse HCC survival, most prominently among patients with systemic inflammation and current smokers. A future trial of folate supplementation seems to be promising in HCC patients with lower folate status.
We consider an M/M/1 retrial queue subject to negative customers (called as G-retrial queue). The arrival of a negative customer forces all positive customers to leave the system and causes the server to fail. At a failure instant, the server is sent to be repaired immediately. Based on a natural reward-cost structure, all arriving positive customers decide whether to join the orbit or balk when they find the server is busy. All positive customers are selfish and want to maximize their own net benefit. Therefore, this system can be modeled as a symmetric noncooperative game among positive customers and the fundamental problem is to identify the Nash equilibrium balking strategy, which is a stable strategy in the sense that if all positive customers agree to follow it no one can benefit by deviating from it, that is, it is a strategy that is the best response against itself. In this paper, by using queueing theory and game theory, the Nash equilibrium mixed strategy in unobservable case and the Nash equilibrium pure strategy in observable case are considered. We also present some numerical examples to demonstrate the effect of the information together with some parameters on the equilibrium behaviors.
The second home-made single stage accelerator mass spectrometer (SSAMS) system dedicated to radiocarbon (14C) measurements was built after the first SSAMS system was moved to Guangxi Normal University. With some improvements to the second SSAMS system, the performance has been improved. With the conditions of total ion energy of 200KeV, ions charge states of 1+ and helium as stripper gas, 14C measurements with precision of 0.5% and a background level of 0.5 pMC were achieved. Details of the system and the experimental performance are given here.
Durable antibacterial PAN/Ag NPs nanofiber membrane was prepared by electrospinning. In this study, Ag NPs were composed by applying polyvinyl pyrrolidone as a dispersant and sodium borohydride (NaBH4) as a reductant. The composite nanofiber films and silver nanoparticles were characterized and tested by transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and Brunauer Emmett Teller (BET) and thermogravimetric analysis test. The specific surface area of PAN/Ag NPs (1%) and PAN/Ag NPs (3%) nanofiber membrane were about 25.00 m2/g calculated by the BET equation. It can be seen that the pore sizes of PAN, PAN/Ag NPs (1%), and PAN/Ag NPs (3%) nanofiber membranes were mainly distributed between 30 and 40 nm. The maximum removal rate of PM10, PM2.5, and PM1.0 was about 94%, 89%, and 82%, respectively, indicating it has a good filtering effect. The results also demonstrated that this membrane has bacterial reduction of over 99.9% for E. coli and S. aureus, respectively. In addition, the thermal stability of the fiber membrane with Ag NPs has no clear difference when compared to pure PAN nanofiber membrane and also has better moisture conductivity, indicating it is a potential candidate applied in biopharmaceutical antiseptic protection products.
Muons produced by the Bethe–Heitler process from laser wakefield accelerated electrons interacting with high
materials have velocities close to the laser wakefield. It is possible to accelerate those muons with laser wakefield directly. Therefore for the first time we propose an all-optical ‘Generator and Booster’ scheme to accelerate the produced muons by another laser wakefield to supply a prompt, compact, low cost and controllable muon source in laser laboratories. The trapping and acceleration of muons are analyzed by one-dimensional analytic model and verified by two-dimensional particle-in-cell (PIC) simulation. It is shown that muons can be trapped in a broad energy range and accelerated to higher energy than that of electrons for longer dephasing length. We further extrapolate the dependence of the maximum acceleration energy of muons with the laser wakefield relativistic factor
and the relevant initial energy
. It is shown that a maximum energy up to 15.2 GeV is promising with
on the existing short pulse laser facilities.
In inertial confinement fusion experiments that involve short-laser pulses such as fast ignition (FI), diagnosis of neutrons is usually very challenging because high-intensity γ rays generated by short-laser pulses would mask the much weaker neutron signal. In this paper, fast-response scintillators with low afterglow and gated microchannel plate photomultiplier tubes are combined to build neutron time-of-flight (nTOF) spectrometers for such experiments. Direct-drive implosion experiments of deuterium-gas-filled capsules were performed at the Shenguang-II Upgrade (SG-II-UP) laser facility to study the compressed fuel areal density (〈ρR〉) and evaluate the performance of such nTOF diagnostics. Two newly developed quenched liquid scintillator detectors and a gated ultrafast plastic scintillator detector were used to measure the secondary DT neutrons and primary DD neutrons, respectively. The secondary neutron signals were clearly discriminated from the γ rays from (n, γ) reactions, and the compressed fuel areal density obtained with the yield-ratio method agrees well with the simulations. Additionally, a small scintillator decay tail and a clear DD neutron signal were observed in an integrated FI experiment as a result of the low afterglow of the oxygen-quenched liquid scintillator.
Sterol regulatory element binding protein 1 (SREBP1) has a central regulatory effect on milk fat synthesis. Lipopolysaccharides (LPS) can induce mastitis and cause milk fat depression in cows. SREBP1 is also known to be associated with inflammatory regulation. Thus, in the current study, we hypothesized that LPS-induced milk fat depression in dairy cow mammary epithelial cells (DCMECs) operates via decreased SREBP1 expression and activity. To examine the hypothesis, DCMECs were isolated and purified from dairy cow mammary tissue and treated with LPS (10 µg/ml). LPS treatment of DCMECs suppressed lipid-metabolism-related transcription factor SREBP1 mRNA expression, nuclear translocation and protein expression, leading to reduced triglyceride content. The transcription levels of acetyl-CoA carboxylase-1 and fatty acid synthetase were significantly down-regulated in DCMECs after LPS treatment, suggesting that acetyl-CoA carboxylase-1 and fatty acid synthetase involved in de novo milk fat synthesis was regulated by SREBP1. In summary, these results suggest that LPS induces milk fat depression in dairy cow mammary epithelial cells via decreased expression of SREBP1 in a time-dependent manner.
Porous carbon derived from biomass materials with enrich, low cost, clean, and renewable merits, exhibits various physical and chemical properties. So, it is of great significance to rationally utilize biomass materials for producing porous carbon with low cost to reduce overusing fossil fuel and environmental pollution. In this report, porous carbon has been fabricated using fruits shells of the Paulownia tomentosa by a facile method of KOH-activation. The as-obtained porous carbon containing a larger number of micropores and slight mesopores possesses a high specific surface area (1914.4 m2/g) and well hierarchical porosity. As the anode for sodium ion batteries, the porous carbon sample displays superior cycling stability and rate capability, delivering a reversible specific capacity of 179 mA h/g at 50 mA/g after 100 cycles and a discharge specific capacity of 100 mA h/g at 1 A/g.
To develop a theoretical model explaining the longitudinal changes in the caregiving process for family caregivers of persons with mild cognitive impairment (MCI) in Taiwan.
A longitudinal, grounded theory approach using in-depth face-to-face interviews and an open-ended interview guide. We conducted 42 interviews over a two-year period; each participant was interviewed at least once every six months. All participants were interviewed in their home. The participants total of 13 family caregivers of persons with MCI.
One core theme emerged: “protective preparation.” This reflected the family caregiving process of preparation for a further decline in cognitive function, and protection from the impact of low self-esteem, accidents, and symptoms of comorbidities for the family member with MCI. Protective preparation contained three components: ambivalent normalization, vigilant preparation, and protective management.
Interventions to help family caregivers manage the changes in persons with MCI can reduce caregiver burden. Our findings could provide a knowledge base for use by healthcare providers to develop and implement strategies to reduce caregiver burden for family caregivers of persons with MCI.
A facile synthesis procedure of nitrogen-self-doped porous carbon (NPC) derived from abundant natural biological materials has been presented. The pyrolysis temperature and the weight ratio of Co3O4 to carbon play a key role in determining microscopic structure and electrochemical performances of the final materials. The ordered mesostructures with nanopores in the channel walls provided support for immobilization of well-dispersed Co3O4 nanoparticles. They also served as a highly conductive substrate for effectively alleviating severe particle aggregation during the charge/discharge processes, which prevented capacity fading from deteriorated electric contact between the components. Taking advantage of the interconnected porous structures and high specific surface area (1799 m2/g) of carbon substrate, the Co3O4/NPC composite as anode in lithium-ion battery delivers a stable reversible capacity of 903 mA h/g after 400 cycles. It is expected that by loading other electrode active materials on such carbon material, the manufacture of the promising anode materials with excellent cycle stability is highly possible.
Upgraded heating and current drive (H/CD) systems have been equipped on the Experimental Advanced Superconducting Tokamak (EAST). With the upgraded H/CD systems, the operation space of EAST is extended, and the ability to achieve higher performance is improved. In this paper, a 0.5 dimension transport code named Minute Embedded Tokamak Integrated Simulator (METIS) is applied to predict the EAST operation space and to assess the current drive capability of the 4.6 GHz lower hybrid current drive system. Predictive simulation of several EAST scenarios, including steady-state high confinement mode (H-mode), advanced regime, high normalized beta and high electron temperature, are also performed with the available H/CD systems. The simulation results provide a guidance for forthcoming advanced EAST experiments.
To investigate the prevalence of Cyclospora cayetanensis in a longitudinal study and to conduct a population genetic analysis, fecal specimens from 6579 patients were collected during the cyclosporiasis – prevalent seasons in two urban areas of central China in 2011–2015. The overall incidence of C. cayetanensis infection was 1·2% (76/6579): 1·6% (50/3173) in Zhengzhou and 0·8% (26/3406) in Kaifeng (P < 0·05), with infections in all age groups (P > 0·05). All the isolates clustered in the C. cayetanensis clade based on the small subunit ribosomal RNA gene sequence phylogenetic analysis. There were 45 specimens positive for all the five C. cayetanensis microsatellite loci, and formed 29 multilocus genotypes (MLGs). The phylogenetic relationships of 54 distinct MLGs (including 25 known reference MLGs), based on the concatenated multilocus sequences, formed three main clusters. A population structure analysis showed that the 79 isolates (including 34 known reference isolates) of C. cayetanensis produced three distinct subpopulations based on allelic profile data. In conclusion, we determined the frequency of C. cayetanensis infection in humans in Henan Province. The clonal population structure of the human C. cayetanensis isolates showed linkage disequilibrium and three distinct subpopulations.
Ceratovacuna lanigera Zehntner is a major leaf pest of sugarcane. Widely distributed, it affects both the yield and quality of sugarcane in China. This study aimed to assess real yield and sugar yield losses, and the effect of C. lanigera damage on emergence of newly planted and ratoon cane under current production levels. Field experiments were carried out from 2014 to 2016 in Yunnan Province China. At maturity, plants were harvested and weighed to determine yield, and the effect on sugarcane quality and sucrose content analyzed. Real yield decreased by average of 46,185 kg hm−2 (range: 37,545–61,845 kg hm−2) in damaged versus undamaged areas, with an average yield loss rate of 35.9% (28.5–45.7%). Juice yield decreased by an average of 3.01% (2.4–4.13%) and sucrose content by 6.38% (5.48–8.16%). Juice brix decreased by an average of 7.66°BX (6.95–9.05°BX) and juice gravity purity by 12.35% (8.43–19.97%). In contrast, the reducing sugar content increased by an average of 1.21% (1.01–1.3%). Emergence rates of newly planted cane decreased by an average of 26.0% (24.7–27.3%). The emergence number of ratoon cane decreased by 66,834 hm2 (57,429–76,238 hm−2) and relative emergence loss rates of ratoon cane decreased by an average of 57.8% (57.6–58.0%). These findings confirm that C. lanigera damage severely affects sugarcane yield and quality in Yunnan Province. The results will help the implementation of effective control measures, thereby supporting sustainable development of the Chinese sugar industry.
NiAl-based nanocomposites were successfully fabricated by mechanical alloying proceeded vacuum-hot-pressing sintering, and the mechanical and tribological properties of the NiA–NbC composite were investigated. The results show that the nanostructured powder particles with the average size around 5 nm were successfully obtained by a high-energy-ball mill. After sintering, the composites were consisted of B2-ordered NiAl and NbC second phase, and the crystalline size of the NiAl phase was about 20 nm. The relative density, hardness, and compressive strength of nanostructured NiAl materials increased with increasing the Nb content, which can be attributed to the second phase hardening effect of in situ formed NbC particulates and fine grain strengthening of nanocrystalline NiAl phase. Thereafter, the friction coefficient of the NiAl–3NbC composite was lowered by the addition of silver and that is significantly lower than the NiAl intermetallic compound and NiAl–3NbC composite at elevated temperatures, which was attributed to the lubricating films formed in sliding process at elevated temperatures. While the wear rates of NiAl–3NbC–10Ag composites are higher than that of the NiAl–3NbC composites at each test temperature, especially at 500 °C and 700 °C, which might be attributed to the phase variations on the worn surfaces of the composites.
Field surveys indicate that host population size, rather than density, is the most important determinant of monogenean infection dynamics. To verify this prediction, epidemic parameters were monitored for 70 days at five host population sizes held at constant density using a goldfish – Gyrodactylus kobayashii laboratory model. During the first 20 days, the rate of increase of prevalence and mean abundance was faster in small host populations. Total mean prevalence and total mean abundance throughout the experiment were not significantly affected by host population sizes. Higher transmission rates were detected in larger host populations. However, there were no significant differences in effective contact rates among the five host populations on each sampling day during the first 20 days, implying that contact rates may be saturated at a sufficiently high host density. These results demonstrate that the epidemic occurs more quickly in smaller host populations at the beginning of the experiment. However, the epidemic is independent of the host population size due to the similar effective contact rates in the five population sizes. Significant negative influence of the initial body condition (Kn) of uninfected goldfish on total mean abundance of parasites suggests that susceptibility of hosts is also a determinant of parasite transmission.
Palaeoproterozic metasedimentary rocks, also referred to as khondalites, characterized by Al-rich minerals, are extensively exposed in the nucleus of the Yangtze craton, South China block. Samples of garnet–sillimanite gneiss in the khondalite suite were collected from the Kongling complex for Nd isotopic and elemental geochemical study. These rocks are characterized by variable SiO2 contents ranging from 35.71 to 58.07 wt%, and have low CaO (0.45–0.84 wt%) but high Al2O3 (18.56–29.04 wt%), Cr (174–334 ppm) and Ni (42.5–153 ppm) contents. They have high CIW (Chemical Index of Weathering) values (90.4–94.7), indicating intense chemical weathering of the source material. The samples display light rare earth elements (LREE) enrichment with negative Eu anomalies (Eu/Eu*=0.40–0.68), and have flat heavy rare earth elements (HREE) patterns. The high contents of transition elements (e.g. Cr, Ni, Sc, V) and moderately radiogenic Nd isotopic compositions suggest that the paragneisses might be those of first-cycle erosion products of predominantly mafic rocks mixing with small amounts of felsic moderately evolved Archaean crustal source. Geochemical and Nd isotopic compositions reveal that at least some of the protoliths of Kongling khondalite were sourced from local pre-existing mafic igneous rocks in a continental arc tectonic setting. Combined with documented zircon U–Pb geochronological data, we propose that the Palaeoproterozoic high-pressure granulite-facies metamorphism, rapid weathering, erosion and deposition of the khondalites in the interior of the Yangtze craton might be related to a Palaeoproterozoic collisional orogenic event during 2.1–1.9 Ga, consistent with the worldwide contemporary orogeny, implying that the Yangtze craton may have been an important component of the Palaeoprotorozoic Columbia supercontinent.
Aiming at a fusion reactor, two issues must be solved for the lower hybrid current drive (LHCD), namely good lower hybrid wave (LHW)–plasma coupling and effective current drive at high density. For this goal, efforts have been made to improve LHW–plasma coupling and current drive capability at high density in experimental advanced superconducting tokamak (EAST). LHW–plasma coupling is improved by means of local gas puffing and gas puffing from the electron side is taken as a routine way for EAST to operate with LHCD. Studies of high density experiments suggest that low recycling and high lower hybrid (LH) frequency are preferred for LHCD experiments at high density, consistent with previous results in other machines. With the combination of 2.45 GHz and 4.6 GHz LH waves, a repeatable high confinement mode plasma with maximum density up to
was obtained by LHCD in EAST. In addition, in the first stage of LHCD cyclic operation, an alternative candidate for more economical fusion reactors has been demonstrated in EAST and further work will be continued.