Isolation and Characterization of Yunnan Variants of the Pseudorabies Virus and Their Pathogenicity in Rats.

Porcine pseudorabies has long existed in China and is a serious threat to the Chinese farming industry. To understand the prevalence and genetic variation of the porcine pseudorabies virus (PRV) and its pathogenicity in Yunnan Province, China, we collected 560 serum samples across seven Yunnan Province regions from 2020 to 2021 and detected anti-gE antibodies in these samples. Sixty-one clinical tissue samples were also collected from pigs with suspected PRV that were vaccinated with Bartha-K61. PRV-gE antibodies were found in 29.6% (166/560) of the serum samples. The PRV positivity rate in clinical tissue samples was 13.1% (8/61). Two isolates, PRV-KM and PRV-QJ, were obtained. The identity of the gB, gD, and gE genes between these isolates and the Chinese mutants exceeded 99.5%. These isolates and the classical Fa strain were used to infect 4-week-old rats intranasally to assess their pathogenicity. All infected rats showed the typical clinical and pathological features of PRV two days post-infection. The viral loads in the organs differed significantly among the infected groups. Viruses were detected in the saliva and feces at 12 h. Significant dynamic changes in total white blood cell counts (WBC), lymphocyte counts (Lym), and neutrophil counts (Gran) occurred in the blood of the infected groups at 24 and 48 h. These results show that mutant PRV strains are prevalent in Bartha-K61-vaccinated pigs in Yunnan Province, China. Moreover, rats shed PRV in their saliva and feces during early infection, indicating the need for rodent control in combatting PRV infections in Yunnan Province, China.

Comparison of machine learning approaches for radioisotope identification using NaI(TI) gamma-ray spectrum.

This research aims at comparing the performance of different machine learning algorithms used for NaI(TI) gamma-ray detector based radioisotope identification. Six machine learning algorithms were implemented, including support vector machine (SVM), k-nearest neighbor (KNN), logistic regression (LR), naive Bayes (NB), decision tree (DT), and multilayer perceptron (MLP). The hyper-parameters of each model were elaborately optimized. The effects of data size, statistical fluctuation, and spectrum drift were considered. Results show that for smaller data size (5 types of radioisotopes and 6000 spectra), the support vector machine and the logistic regression classifier exhibit higher identification accuracy with less training/predicting time. Whereas for larger data size (14 types of radioisotopes corresponding to the standard IEC 62327-2017), the multilayer perceptron showed highest accuracy but required the longest time for model training. The naive Bayes classifier and the decision tree were prone to make mistakes when fluctuations and distortions were added to the spectra. The k-nearest neighbor classifier, though showing high accuracy for most data sets, consumed the longest time while making prediction.

Migration behavior and leaching ability of radioactive uranium during incineration of uranium-containing strippable coating wastes.

It is currently thought that the incineration approach is an effective method to minimize the volume of radioactive wastes. In this paper, we used an incinerator to burn uranium-containing strippable coating waste. The migration behavior of radioactive uranium during the incineration process were investigated based on hierarchical sampling and mass spectrometry. Results shows that the radioactive uranium is more easily to adhere to the particles with smaller size. The leaching abilities of radioactive uranium in the bottom ash and the fly ash were analyzed. The leaching rate of the uranium from the fly ash and bottom ash were 1% and 6%, respectively, indicating that most of the radioactive uranium was fixed in the ash and the same storage/disposal methods can be used for both the fly ash and bottom ash. According to x-ray spectrometry and SEM-EDS, mineral compositions of the original uranium ore and the bottom ash were mostly the same. Calcium plays an important role in uranium fixation during incineration. The potential mechanism of the uranium special transformation during uranium-containing strippable coating waste combustion was revealed. Our research results can provide technical support for nuclear emergency waste treatment and disposal.

Adsorption behavior of Cs(I) on natural soils: Batch experiments and model-based quantification of different adsorption sites.

Understanding the adsorption behavior of radiocesium (RCs) in natural soils is crucial for remediation and evaluation of radioactive contaminated sites. In this study, we investigated the adsorption behavior of Cs(I) onto natural soils collected in Beijing by batch adsorption experiments and sequential extraction. A multi-site adsorption model was built to quantitatively analyze the adsorption capacities of soil clay minerals and predict of Cs(I) adsorption ratio of different adsorption sites. Linear programming calculations show that illite/smectite (I/S) mixture and illite(I) are the mainly clay mineral composition. Batch adsorption experiment results show that soils adsorption of Cesium ions is an exothermic process, and the order of influence of competitive cations on the competitive adsorption strength of Cs(I) is:K+>Mg2+≈Ca2+>Na+. HA (Humic Acid)has little effect on soil adsorption. SEM-EDS analysis shows that Cs+ is mainly distributed on the surface (PS) of soil particles. Based on the above results, the adsorption of Cs(I) onto clay minerals in soils is well predicts in both linear programming calculations and a multi-site adsorption model. The multi-site adsorption model can quantitatively describe and predict the adsorption behavior of Cs(I) on different clay sites in the soils. Frayed edge sites (FES) in the soil can effectively fix trace RCs. The higher concentration of cesium ions is mainly adsorbed on the PS and TIIS. Sequential extraction experiment further proved the adsorption form of cesium in soil under trace and high concentration conditions.

FIELD MEASUREMENT OF THE UNATTACHED FRACTION AND ACTIVITY CONCENTRATION RATIO OF RADON PROGENY IN TYPICAL DWELLINGS.

The unattached fraction (fp) and activity concentration ratio of radon progeny (${\boldsymbol C}_{{}{}^{\bf 218}\bf{Po}}:{\boldsymbol C}_{{}{}^{\bf 214}\bf{Pb}}:{\boldsymbol C}_{{}{}^{\bf 214}\bf{Bi}}$) are important for radon exposure dose evaluation. For getting these characteristic parameters in dwellings, a series of field measurement was carried out. For comparison, a semi-continuous measurement was carried out in an office room and outdoors. Results show that the average fp is 4.5% ± 2.2% and 3.8% ± 1.7% in city dwellings and in rural dwellings, respectively. The average activity concentration ratios are 1:0.94:0.70 for radon progeny and 1:0.07:0.06 for unattached radon progeny in city dwellings, while those in rural dwellings are 1:0.88:0.66 and 1:0.09:0.07. The average values of fp are 5.1% ± 0.9% and 5.4% ± 3.1% in the office room and in outdoors without significant difference. The average activity concentration ratios are 1:0.88:0.77 for radon progeny and 1:0.11:0.11 for unattached radon progeny in outdoors.

Study on acrylate peelable nuclear detergent for film formation at low temperature.

The human handling of radioactive contamination on the surface of nuclear facilities has become an important issue in the development of nuclear industry. In order to solve the poor film-forming of nuclear detergent in low temperature, a new type low temperature film-forming peelable nuclear decontaminant was proposed. The acrylate copolymers were developed by solution polymerization of acrylic monomers in the mass ratio of BA (butyl acrylate): MMA (methyl methacrylate): AA (acrylic acid): EA (ethyl acetate) is equal to 50:45:5:100 considering different proportioning methods and reaction temperature. Then the orthogonal test was carried out to study the effects of crosslinker, plasticizer, thickener, release agent on the decontamination performance based on the orthogonal test method, and the optimal peelable formula of peelable nuclear detergent was obtained. Next the infrared properties, glass transition temperature, molecular weight of polymer and decontamination efficiency of peelable nuclear decontaminant were studied by experiments. The results show that the proposed low-temperature film-forming peelable radioactive decontamination agent can form film on concrete, sand, terrazzo, stainless steel and other surfaces, and is easy to peel off. The decontamination rate of this material is more than 82%.

Comparison measurement of unattached radon progeny concentration in three different environments.

Accurate measurement of unattached radon progeny is important for dose evaluation of radon exposure. For quality control of field surveys, a series of comparison measurements were carried out using three commercial unattached radon progeny monitors in real environments as well as in a radon chamber. The results show that the radon equilibrium equivalent concentrations (EECs) of different monitors agree very well, mostly within ±3.0% where there is no thoron progeny interference in the radon chamber. However, the unattached fraction of radon progeny is not so consistent, and the relative difference is 3.3% ~ 39.5% in different environments. The unattached fraction of radon progeny is affected by aerosol concentration. Anomalously high unattached fraction was found in the environment with extremely high humidity and low aerosol concentration. For accurate measurement of unattached radon progeny, specific attention should be paid to the collection efficiency of unattached radon progeny and the interference of attached radon progeny on a wire screen.

NEW DEVELOPMENT OF RADON PROGENY MEASUREMENT METHOD BASED ON ALPHA-BETA SPECTROMETRY.

Accurate measurement of radon progeny concentration is important for the dose assessment of radon exposure and the study of radon progeny behaviours. For measuring 218Po, 214Pb and 214Bi concentration as well as EEC with high sensitivity, an alpha-beta spectrometry method was developed and applied in a step-advanced filter radon progeny monitor. The derivation details of this method is given in this paper and the uncertainty is discussed. The comparison experiments are carried out in radon chamber and in field. Results show that the alpha-beta spectrometry method can give 218Po, 214Pb and 214Bi concentration as well as EEC with high sensitivity either for 60 min or for 30 min cycle, which leads to low uncertainty. This method can be used as a reference method for radon chamber and is suitable for portable radon progeny monitor.

ytiB and ythA Genes Reduce the Uranium Removal Capacity of Bacillus atrophaeus.

Two Bacillus atrophaeus strains, the first being a highly stress-resistant ATCC 9372 strain and the Ua strain identified from a chromium mine by our lab, differ in their abilities to tolerate and remove Uranium (VI) from contaminated water. An increase in U(VI) concentration in growth media led to a decrease in the tolerance and bio-remedial capacity of both strains. However, under high concentrations of U(VI) in the growth media, the ATCC 9372 strain demonstrated a higher tolerance and a higher removal capacity than the Ua strain. Two approaches, transcriptome sequencing and transgenic technology, were used to elucidate the relationship between particular genes within these two strains and their U(VI) removal capacity. Sequencing confirmed the expression of two genes unique to the Ua strain, previously designated ytiB and ythA. They encode putative proteins that show the highest levels of identity to carbonic anhydrase and cytochrome bd terminal oxidase I, respectively. Using the pBE-S DNA vector, ytiB and ythA were transformed into the ATCC 9372 strain of Bacillus atrophaeus. Under a U(VI) concentration of 120 mg/L, the removal rates of the transgenic ATCC 9372-ytiB and ATCC 9372-ythA strains decreased by 7.55% and 7.43%, respectively, compared to the removal rate of the control strain transformed with empty plasmid. The results suggest that both ythA and ytiB genes have a negative influence on the uranium removing capacity of Bacillus atrophaeus. This finding will help to elucidate the molecular mechanisms of uranium removal by bacteria.

Chemoselective reduction of α,ß-unsaturated aldehydes using an unsupported nanoporous gold catalyst.

The remarkable effect of an unsupported nanoporous gold catalyst (AuNPore) on chemoselective hydrogenation of α,ß-unsaturated aldehydes using silane has been described. Enals can be reduced with excellent selectivity, giving the corresponding allylic alcohols in good to high chemical yields.

Accurate measurement of the radon exhalation rate of building materials using the closed chamber method.

The construction department of the Chinese government is now discussing the possibility of reducing indoor radon exposure through controlling the radon exhalation rate of building materials. However, which quantity is suitable for control and how to specify and measure this quantity are still not clear. A comparison of a theoretical model and measurement process of radon exhalation between the surface of soil and building materials was carried out. As a result, the so-called intrinsic exhalation rate is thought to be a suitable quantity for control. Through theoretical analysis and experimental comparisons of different pre-treatment methods, it was indicated that the closed chamber method could be used to measure the intrinsic exhalation rate of building materials. Measurement results show that the average intrinsic radon exhalation rate of building materials commonly used in Beijing is 4.891 mBq m(-2) s(-1), with a range of 0.323-21.250 mBq m(-2) s(-1), and the average diffusion length is 16.448 cm, with a range of 2.371-41.960 cm.