[Pollution Characteristics and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Farmland Soil and Crops in the Suburbs of Urumqi].

In order to understand the occurrence of PAHs in soil and crops, the enrichment capacity of different crops for PAHs, and the distribution characteristics of PAHs in different parts of crops, the crops and soil planted in the farmland around Urumqi were studied as examples. Samples were collected in the farmland gathering area in the suburb of Urumqi in July 2021. A total of 100 crop samples were collected, including 21 crop species and 45 surface soil samples. The results showed that 16 types of PAHs were detected in the soil and crops. The total concentration of PAHs in farmland soil ranged from 19.06 to 1870.86 µg·kg-1, and the average concentration was 127.40 µg·kg-1. Seven carcinogenic PAHs accounted for 42.85%-79.20% of the 16 types of PAHs, among which BaP was the main pollutant in the soil. Through the characteristic ratio method, it was found that the main sources of PAHs in the soil were biomass and coal combustion. Total PAHs in crops ranged from 1.86 µg·kg-1 to 974.05 µg·kg-1, with an average of 303.30 µg·kg-1. Different crops had different enrichment capacities for PAHs. Among the 21 crops sampled, the accumulative content of PAHs in pumpkin was the highest (431.75 µg·kg-1). In leaf vegetable crops, the content of PAHs in leaves was higher than that in roots and fruits. In fruit and vegetable crops, the PAH content in fruit was higher than that in the root or leaf. There was a significant correlation between high cyclic PAHs in soil and PAHs in plant leaves. The health risk assessment of PAHs in crops showed that dietary intake had potential carcinogenic risk and even had high carcinogenic risk in adult male and female groups, which requires further attention.

Design of Ultra-High Extinction Ratio TM- and TE-Pass Polarizers Based on Si-Sc0.2Sb2Te3 Hybrid Waveguide.

The selective polarizers play an important role in silicon-based integrated circuits. The previous polarizers based on silicon waveguides have the defects of large scale and low extinction ratio. In this work, TM- and TE-pass polarizers only 10 µm long were developed based on phase-change material of Sc0.2Sb2Te3 (SST) hybrid silicon waveguide, where several SST bars with a varied distance was designed. Because of the excellent characteristics of the refractive index of the material, ultra-high extinction ratios (ERs) were achieved. A 3-D finite element simulation was carried out to optimize the structure of the polarizers, and the distribution of light field, as well as the transmission behavior of TE and TM modes in the two polarizers, was further demonstrated in detail. When the SST is crystalline, the unwanted mode can be attenuated, while the wanted mode can pass through with low loss. Compared with the GST-based polarizers, the proposed ones achieved high extinction ratios of ~43.12 dB (TM-pass one) and ~44.21 dB (TE-pass one), respectively; at the same time, ILs for the wanted modes could be negligible. The design of high-performance polarizers paves a new way for applications of all-optical integrated circuits.

[Typical Pesticide Residues and Their Risk Assessment in Farmland Environment of Different Plant Types in Shaya County, Xinjiang].

In order to investigate the characteristics of typical pesticide residues in farmland soil of different plant types in Shaya County and to evaluate the level of human health risk and ecological risk caused by pesticide residues, a total of 55 samples of plants, soil, and water from nine areas of Shaya county were collected on September 29, 2020. The occurrence levels of 47 typical pesticides in the samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The results showed that a total of 23 pesticides were detected in three environmental media, and the maximum concentrations of pesticides in soil, plants, and water were 70.58 µg·kg-1, 1832.18 µg·kg-1, and 188.53 µg·L-1, respectively. The levels of pesticide residues in the three environmental media in Shaya county were characterized as plants>water>soil. From the detection of pesticides in different plant types, P1, P2, P6, and P8 in the center of the county were the most seriously polluted. The plants with a high pesticide load level in the corresponding areas were cotton, walnut, red jujube, and poplar, and the pesticides with a high concentration contribution were hexachlorocyclohexanes, chlorpyrifos, cyhalothrin, fluvalinate, metalaxyl, difenoconazole, and procymidone. The human health risks of adults and children caused by oral intake, skin contact, and respiratory inhalation were evaluated. The results showed that oral intake was the main exposure route, and the risk level of children was significantly higher than that of adults but was within the acceptable range. The ecological risk level of earthworms in soil was subsequently evaluated. The results showed that the potential ecological risk level of a single pesticide was low, and the potential ecological risk level of bifenthrin was the largest. The calculation of the total ecological risk of mixed pesticides showed that areas P1, P4, P7, and P9 were at moderate risk, whereas other areas were at low risk. Therefore, the use of some pesticides in Shaya County should be restricted.

Refractive status and optical components in premature infants with and without retinopathy of prematurity: A 4- to 5-year cohort study.

This study was aimed to investigate the characteristics of refractive parameters in premature infants and children aged 3-8 years with mild retinopathy of prematurity (ROP) and to explore the effects of premature delivery and mild ROP on the development of refractive status and ocular optical components. Premature infants who underwent ocular fundus oculi screening in our hospital between January 2009 and February 2011 were included and divided into the ROP group and the non-ROP group. Full-term infants were the controls. The results of the annual ocular examination conducted between 2014 and 2018 were analysed, and the refractive status, optical components, and developmental trends were compared among the three groups. The total follow-up time was 4-5 years. The prevalence of myopia and astigmatism was high in the ROP group (P < 0.05). In the non-ROP group, the prevalence of myopia was also higher than that in the control group. The prevalence of myopia increased with age in the ROP and non-ROP groups, while the prevalence of astigmatism remained unchanged. In the ROP group, the corneal refractive power was the largest, the lens was the thickest and the ocular axis was the shortest; in the control group, the corneal refractive power was the smallest, the lens was the thinnest, and the ocular axis was the longest. These parameters in the non-ROP group were between those in the two groups mentioned above (P < 0.05). The corneal refractive power was relatively stable at 3-8 years old in the three groups. The change in lens thickness was small in both the ROP group and the non-ROP group (P = 0.75, P = 0.06), and the lens became thinner in the control group (P < 0.001). The length of the ocular axis increased in the three groups. Preterm infants are more likely to develop myopia than full-term infants, and children with ROP are more likely to develop both myopia and astigmatism. Thicker lenses were the main cause of the high prevalence of myopia in premature infants with or without ROP.