Electron stochastic acceleration in laboratory-produced kinetic turbulent plasmas.

The origin of energetic charged particles in universe remains an unresolved issue. Astronomical observations combined with simulations have provided insights into particle acceleration mechanisms, including magnetic reconnection acceleration, shock acceleration, and stochastic acceleration. Recent experiments have also confirmed that electrons can be accelerated through processes such as magnetic reconnection and collisionless shock formation. However, laboratory identifying stochastic acceleration as a feasible mechanism is still a challenge, particularly in the creation of collision-free turbulent plasmas. Here, we present experimental results demonstrating kinetic turbulence with a typical spectrum k-2.9 originating from Weibel instability. Energetic electrons exhibiting a power-law distribution are clearly observed. Simulations further reveal that thermal electrons undergo stochastic acceleration through collisions with multiple magnetic islands-like structures within the turbulent region. This study sheds light on a critical transition period during supernova explosion, where kinetic turbulences originating from Weibel instability emerge prior to collisionless shock formation. Our results suggest that electrons undergo stochastic acceleration during this transition phase.

Contamination and health risks brought by arsenic, lead and cadmium in a water-soil-plant system nearby a non-ferrous metal mining area.

Heavy metal(loid)s contamination prevails in the water-soil-plant system around non-ferrous metal mining areas. The present study aimed to evaluate the heavy metal(loid)s contamination in Nandan Pb-Zn mining area (Guangxi, China). A total of 36 river water samples, 75 paired paddy soil and rice samples, and 128 paired upland soil and plant samples were collected from this area. The concentrations of arsenic (As), lead (Pb), and cadmium (Cd) in these samples were measured. Results showed that the average water quality indexes (WQIs) at the 12 sampling sites along the main river ranged from 41 to 5008, indicating the water qualities decreasing from "Excellent" to "Undrinkable". The WQIs nearby tailings or industrial park were significantly higher than those at the other sites. 34.0% and 64.5% of soil samples exceeded the risk screening values for As and Cd. The Pb and Cd concentrations in all rice samples exceeded the Chinese food safety limits by 18.7% and 82.7%, respectively. Leafy vegetables had a higher concentration of As, Pb, and Cd than other vegetables, exceeding the maximum permissible limits by 14.1%, 61.2%, and 40.0%, respectively. The biological accumulation coefficient (BAC) of Cd was the highest in rice and lettuce leaves. The hazard quotients (HQs) of As and Cd, indicating non-carcinogenic risks, were 4.15 and 1.76 in adult males, and 3.40 and 1.45 in adult females, all higher than the permitted level (1.0). The carcinogenic probabilities of As and Cd from rice and leafy vegetables consumption were all higher than 1 × 10-4. We conclude that metal(loid)s contamination of the water-soil-plant system has posed great non-carcinogenic and carcinogenic risks to the local population.

Association of lead and cadmium exposure with kidney stone incidence: A study on the non-occupational population in Nandan of China.

BACKGROUND: Environmental lead (Pb) and cadmium (Cd) pollution has been considered a risk factor in the etiology of kidney stones. However, the association between Pb and Cd exposure and kidney stone incidence has yet to be determined. OBJECTIVES: This study aimed to determine a possible the association between kidney stones with Pb and Cd exposure (alone or combined) in a non-occupational population. METHODS: Pb and Cd contaminations in soil-plant system were determined by flame atomic absorption spectrophotometry. Health risk assessment of dietary Pb or Cd intake from rice and vegetables were calculated. Kidney stones were diagnosed with urinary tract ultrasonography. Urinary cadmium (UCd) and blood lead (BPb) levels were determined by graphite-furnace atomic absorption spectrometry. Multivariate logistic regression models were constructed. RESULTS: The hazard indexes (HI) of Pb and Cd were 7.91 and 7.31. The odds ratio (OR) was 2.83 (95 %CI:1.38-5.77) in males with high BPb (BPb ≥ 100 µg/L), compared with those with low BPb (BPb＜100 µg/L). Compared to those with low BPb and low UCd (BPb＜100 µg/L and UCd＜2 µg/g creatinine), the ORs were 2.58 (95 % CI:1.17-5.70) and 3.43 (95 % CI:1.21-9.16) in females and males with high BPb and high UCd (BPb ≥100 µg/L and UCd ≥2 µg/g creatinine), respectively. The OR was 3.16 (95 % CI:1.26-7.88) in males with high BPb and low UCd (BPb ≥ 100 µg/L and UCd ＜2 µg/g creatinine), compared to those with low BPb and low UCd. CONCLUSIONS: Kidney stones incidence was increased by high Pb exposure in males, and by Pb and Cd co-exposure in males and females.

[Characteristics of Organic and Elemental Carbon in PM10 and PM2.5 in Yulin City, Guangxi].

Two hundred eighteen PM10 and 202 PM2.5 samples were collected at three sampling sites to study the pollution characteristics of carbonaceous aerosols in Yulin from July 2015 to March 2016. Organic carbon (OC) and elemental carbon (EC) in the PM10 and PM2.5 samples were analyzed by a Multiwavelength Thermal/Optical Carbon Analyzer, and the characteristics, including pollution levels, temporal and spatial distributions, and possible sources of OC and EC, were investigated. The results showed that the OC and EC mass concentrations in PM10 in Yulin were 10.99 and 5.11 µg·m-3, respectively, while the OC and EC mass concentrations in PM2.5 were 7.51 and 4.70 µg·m-3, respectively. Strong correlations between OC and EC were found in PM10(R2=0.58) and PM2.5(R2=0.60). The winter average concentrations of secondary organic carbon (SOC) in PM10 and PM2.5 were 14.50 µg·m-3 and 6.74 µg·m-3, respectively. The SOC/OC ratios in both the PM10 and PM2.5 were higher than 0.5. The contribution of SOC to OC was 80.6% in PM10 and 77.7% in PM2.5, which were the highest in the summer, in accordance with the high temperature and strong solar radiation in the summer.

Online single particle measurement of fireworks pollution during Chinese New Year in Nanning.

Time-resolved single-particle measurements were conducted during Chinese New Year in Nanning, China. Firework displays resulted in a burst of SO2, coarse mode, and accumulation mode (100-500nm) particles. Through single particle mass spectrometry analysis, five different types of particles (fireworks-metal, ash, dust, organic carbon-sulfate (OC-sulfate), biomass burning) with different size distributions were identified as primary emissions from firework displays. The fireworks-related particles accounted for more than 70% of the total analyzed particles during severe firework detonations. The formation of secondary particulate sulfate and nitrate during firework events was investigated on single particle level. An increase of sulfite peak (80SO3-) followed by an increase of sulfate peaks (97HSO4-+96SO4-) in the mass spectra during firework displays indicated the aqueous uptake and oxidation of SO2 on particles. High concentration of gaseous SO2, high relative humidity and high particle loading likely promoted SO2 oxidation. Secondary nitrate formed through gas-phase oxidation of NO2 to nitric acid, followed by the condensation into particles as ammonium nitrate. This study shows that under worm, humid conditions, both primary and secondary aerosols contribute to the particulate air pollution during firework displays.

Formation and evolution of a pair of collisionless shocks in counter-streaming flows.

A pair of collisionless shocks that propagate in the opposite directions are firstly observed in the interactions of laser-produced counter-streaming flows. The flows are generated by irradiating a pair of opposing copper foils with eight laser beams at the Shenguang-II (SG-II) laser facility. The experimental results indicate that the excited shocks are collisionless and electrostatic, in good agreement with the theoretical model of electrostatic shock. The particle-in-cell (PIC) simulations verify that a strong electrostatic field growing from the interaction region contributes to the shocks formation. The evolution is driven by the thermal pressure gradient between the upstream and the downstream. Theoretical analysis indicates that the strength of the shocks is enhanced with the decreasing density ratio during both flows interpenetration. The positive feedback can offset the shock decay process. This is probable the main reason why the electrostatic shocks can keep stable for a longer time in our experiment.

[Physiochemical Properties and Sources of Atmospheric Particulate Matter During Pollution Monitoring in Nanning, China].

Distribution characteristics, chemical constituents, and sources of particulate matter were measured using a scanning mobility particle sizer and single particle aerosol mass spectrometer during pollution monitoring that occurred between December 5th and December 11th, 2016, in Nanning. Results showed that particulate matter (PM) sized between 20 nm-10 µm were concentrated in the 23 to 395 nm range, with a peak of 100 nm. Three new particle types were generated during the course of this monitoring. These new 30 nm particles came into existence between 14:00 to 18:00, and grew to a size of between 40 nm and 110 nm between 20:00 to 06:00 the next day. The generation of the all three new particles was affected by motor vehicle exhaust emissions. Many secondary particles were also produced during this period of pollution. The source of the fine particulate matter was mainly from the burning of biomass, dust, and the combustion of coal. In addition, a long-distance transmission also contributed to the particles from biomass burning.

[Analysis of Chemical Composition and Pollution Source of the Fine Particulate Matter by the SPAMS in the Four Seasons in Nanning].

To study the chemical composition and pollution sources of the fine particulate matter during the four seasons in Nanning, single particle aerosol mass spectrometry was performed to characterize the fine particulate matter in Nanning during the four seasons. The correlation (R2) between the fine particulate matter number concentration and the mass concentration of the fine particulate matter obtained using SPAMS was all above 0.75 in the observation period. The particle number concentration could reflect the atmospheric pollution situation to some degree. The average mass spectrogram of the fine particulate matter reflected that secondary pollutants were more in winter and spring in Nanning. The Art-2a classification method was used to classify the chemical composition of the fine particulate matter. The results showed that the number concentration of the chemical composition and sources of pollution had differences in the four seasons. Chemical composition could reflect pollution sources. The elevated elemental carbon was positively with increasing coal combustion in winter. The elevated organic carbon was positively correlated with motor vehicle source in autumn. Rich potassium particles, levoglucosan and substance were positively correlated with biomass burning source and dust in summer. The rich sodium particles and heavy metals were higher in spring. During the process of increasing pollution, the contributions of biomass and coal combustion sources were large.

Paraoxonase-1 (PON1) rs662 Polymorphism and Its Association with Serum Lipid Levels and Longevity in the Bama Zhuang Population.

BACKGROUND The present study was performed to identify the association of PON1 rs662 polymorphism with serum lipid levels and human longevity in the Bama Zhuang population. MATERIAL AND METHODS PON1 genotypes were determined by Taqman SNP Genotyping Assays in 110 long-lived inhabitants (longevity group, aged 90-110 years), 110 healthy inhabitants in Bama County (control 1 group, aged 43-82 years) and 110 healthy inhabitants in Nandan County (control 2 group, aged 28-82 years) without family history of longevity. RESULTS BMI (body mass index) and TG (serum total triglyceride) level were lower in the longevity group than in the two control groups, while the contents of serum LDL-c (low-density lipoprotein cholesterol) and HDL-c (high-density lipoprotein cholesterol) and the levels of SBP (systolic blood pressure) and DBP (diastolic blood pressure) in the longevity group were higher than in the two control groups (p<0.01). Significant differences in the frequencies of three genotypes (GG, AG, and AA) were observed between the longevity group and control 2 group (χ²=15.190, p=0.001). The minor allele frequency (MAF) of rs662 was significantly higher in the longevity group than in the two control groups. The levels of HDL-c in the longevity group were different among the three genotypes (p<0.05). The levels of TG for GG and GG+AG genotypes were significantly different, while the levels of TC (total cholesterol) and HDL-c for AG and GG+AG genotypes were significantly different among the three groups (p<0.05). Serum lipid parameters were correlated with several environmental factors, including age, gender, DBP, SBP, and BMI. The association of PON1 rs662 polymorphism and serum lipid levels was different among the three groups. CONCLUSIONS PON1 polymorphism might be one of the genetic factors of longevity in the Bama Zhuang population. The PON1 rs662 SNP (single nucleotide polymorphism) was associated with serum HDL-c levels in the longevity group.

Association of SIRT6 Gene Polymorphisms with Human Longevity.

BACKGROUND: We aimed to identify the role of SIRT6 gene polymorphism rs350846 in human longevity. METHODS: SIRT6 C/G genotypes were determined using Taqman SNP Genotyping Assays in 169 long-lived inhabitants (LG group aged 90-110 yr), 158 healthy internal controls (internal control group; aged 26-82 yr) and 176 healthy external controls (external control group; aged 20-82 yr) without a family history of exceptional longevity. Statistical analysis was conducted using SPSS 16.0. RESULTS: BMI and TG level were lower in the longevity than in the two control groups, while serum LDL-c and HDL-c and SBP and DBP levels in long-lived individuals were higher than in the two control groups (P<0.01). The waist circumference was obviously different (P=0.001) among the three groups, with the maximum observed in the external group. No statistically significant differences of the gender FBG and TC were seen in long-lived individuals than in the two control groups. Significant genotype differences existed among the different groups except for the longevity and internal control group. The frequency of the minor allele-C was 0.319. The minor allele frequency of rs350846 in SIRT6 was much higher in the external control than in the other groups. BMI, SBP and HDL-c displayed significant effect on longevity. CONCLUSION: The C allele of rs350846 in SIRT6 gene, CC and CG genotypes as well as BMI, systolic pressure and HDL-c are associated with longevity. Further studies are needed to validate our results.

[Chemical Composition of the Single Particle Aerosol in Winter in Nanning Using SPAMS].

Single Particle Aerosol Mass Spectrometry (SPAMS) was performed to characterize the PM2.5 in Nanning from 15 to 24 February 2015. The correlation (R2) between the PM2.5 number concentration and the mass concentration of PM2.5 obtained using SPAMS was 0.76. The particle number concentration could reflect the atmospheric pollution situation to some degree. The Art-2a classification method was used to classify the chemical composition of PM2.5. The results showed that the principal chemical constituents were elemental carbon, organic elements carbon hybrid particles, organic carbon, rich potassium particles, mineral substance, rich sodium particles, second inorganic particles, levoglucosan and other heavy metals. Among them, the composition of elemental carbon was the highest, followed by organic carbon and rich potassium particles. The particle size of 80% of PM2.5 was mainly concentrated in the range of 0.2 microm to 1.0 microm with a peak value occurring at 0. 62 microm. The particle size distribution characteristics of different chemical components were similar. The number concentration of the chemical components in PM2.5 had the same variation tread with the mass concentration of PM2.5 over time. To a certain extent, the change in chemical composition could reflect the instantaneous pollution source.