An efficient process for wastewater treatment to mitigate free nitrous acid generation and its inhibition on biological phosphorus removal

Free nitrous acid (FNA), which is the protonated form of nitrite and inevitably produced during biological nitrogen removal, has been demonstrated to strongly inhibit the activity of polyphosphate accumulating organisms (PAOs). Herein we reported an efficient process for wastewater treatment, i.e., the oxic/anoxic/oxic/extended-idle process to mitigate the generation of FNA and its inhibition on PAOs. The results showed that this new process enriched more PAOs which thereby achieved higher phosphorus removal efficiency than the conventional four-step (i.e., anaerobic/oxic/anoxic/oxic) biological nutrient removal process (41 ± 7% versus 30 ± 5% in abundance of PAOs and 97 ± 0.73% versus 82 ± 1.2% in efficiency of phosphorus removal). It was found that this new process increased pH value but decreased nitrite accumulation, resulting in the decreased FNA generation. Further experiments showed that the new process could alleviate the inhibition of FNA on the metabolisms of PAOs even under the same FNA concentration

A recombinant avian antibody against VP2 of infectious bursal disease virus protects chicken from viral infection

【Abstract】A stable cell-line was established that expressed the recombinant avian antibody (rAb) against the infectious bursal disease virus (IBDV). rAb exhibited neutralization activity to IBDV-B87 strain in DF1 cells. The minimum rAb concentration required for inhibition of the cytopathic effect (CPE) was 1.563 μg/mL. To test the efficacy of rAb, a 168-h cohabitation challenge experiment was performed to transmit the disease from the chickens challenged with vvIBDV (HLJ0504 strain) to three test groups of chickens, i.e. (1) chickens treated with rAb, (2) chickens treated with yolk antibody, and (3) non-treatment chickens. The survival rates of chickens treated with rAb, yolk antibody and without treatment were 73%, 67% and 20%, respectively. Another batch of chickens was challenged with IBDV (BC6/85 strain) and then injected with rAb (1.0 mg/kg) 6, 24 and 36 h post-challenge. Non-treatment chickens had 100% morbidity, whereas those administered with rAb exhibited only 20% morbidity. Morbidity was evaluated using clinical indicators and bursal histopathological section. This study provides a new approach to treating IBDV and the rAb represents a promising candidate for this IBDV therapy.This research was supported by Heilongjiang province project of applied technology research and development (2013GC13C105) and The National Natural Science Fund biologic science base improve program of research training and capacity (J1210069/J0124)

Comprehensive Analysis of the Relationship Between RAS and RAF Mutations and MSI Status of Colorectal Cancer in Northeastern China

Background/Aims: Colorectal cancer (CRC) is mainly caused by chromosomal instability (CIN) and microsatellite instability (MSI). The RAS and RAF genes are essential components of the CIN pathway, and several studies have found that RAS and RAF mutations are associated with MSI status in CRC. Here, we examined these three factors in CRC in Northeast China and aimed to reveal new details of the relationship between these mutations and MSI status. Methods: This study involved 290 patients with CRC who had RAS or RAF gene mutation detected using fluorescence-based allele-specific polymerase chain reaction or Sanger sequencing. The majority of the identified patients were found to harbor MSI (MSI status). Accurate molecular detection was carried out using formalin-fixed paraffin-embedded tissue or blood samples. Results: The rates of RAS and RAF mutations were 58.5% and 4.1%, respectively. The prevalence of RAS mutation in CRC was clearly higher and that of RAF mutation was lower in Northeast China compared with previously reported cohorts in other locations. High MSI level (MSI-H status) was more complex, at around 10%. This was consistent with previous data from China. However, compared with data reported from other continents, MSI-H was higher than that of Japan or South Korea in Asia, and lower than that of Europe or the United States. Conclusion: RAS/RAF mutations and MSI status in CRC are closely associated with tumor location and ethnicity. Further studies investigating the relationship between these three factors can help in the development of treatment strategies for patients with CRC

Composition, Source Apportionment, and Health Risk of PM_2.5-Bound Metals during Winter Haze in Yuci College Town, Shanxi, China

The composition, source, and health risks of PM2.5-bound metals were investigated during winter haze in Yuci College Town, Shanxi, China. The 24-h PM2.5 levels of 34 samples ranged from 17 to 174 μg·m−3, with a mean of 81 ± 35 μg·m−3. PM2.5-bound metals ranked in the following order: Zn > Cu > Pb > As > Ni > Cr (VI) > Cd > Co. The concentrations of 18% As and 100% Cr (VI) exceeded the corresponding standards of the Ambient Air Quality Standards set by China and the WHO. Subsequently, positive matrix factorization analyses revealed that the three major sources of metals were combustion (37.91%), traffic emissions (32.19%), and industry sources (29.9%). Finally, the non-carcinogenic risks for eight metals indicated that only 2.9% of the samples exceeded a threshold value of one, and As accounted for 45.31%. The total carcinogenic risk values for six metals (As, Cd, Co, Cr (VI), Ni, and Pb) were in the range from 10−6 to 10−4, with Cr (VI) and As accounting for 80.92% and 15.52%, respectively. In conclusion, winter haze in Yuci College Town was characterized by higher metal levels and health risks; among the metals, As and Cr (VI) were probably the main contributors

Optimization of Cancer Risk Assessment Models for PM2.5-Bound PAHs: Application in Jingzhong, Shanxi, China

The accurate evaluation of the carcinogenic risk of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) is crucial because of the teratogenic, carcinogenic, and mutagenic effects of PAHs. The best model out of six models was selected across three highly used categories in recent years, including the USEPA-recommended inhalation risk (Model I), inhalation carcinogen unit risk (Models IIA–IID), and three exposure pathways (inhalation, dermal, and oral) (Model III). Model I was found to be superior to the other models, and its predicted risk values were in accordance with the thresholds of PM2.5 and benzo[a]pyrene in ambient-air-quality standards. Models IIA and III overestimated the risk of cancer compared to the actual cancer incidence in the local population. Model IID can replace Models IIB and IIC as these models exhibited no statistically significant differences between each other. Furthermore, the exposure parameters were optimized for Model I and significant differences were observed with respect to country and age. However, the gender difference was not statistically significant. In conclusion, Model I is recommended as the more suitable model, but in assessing cancer risk in the future, the exposure parameters must be appropriate for each country

Adsorption of Chromium (VI) by Cu (I)-MOF in Water: Optimization, Kinetics, and Thermodynamics

To investigate the adsorption behavior of Cu (I)-MOF material for chromium (VI) in water, the parameters of influencing adsorption were optimized and found as follows: the optimal pH was 6 for the adsorption of Cr (VI) by the Cu (I)-MOF, the optimal amount of adsorbent was 0.45 g·L−1, and the adsorption saturation time was within 180 min. Subsequently, the kinetics results were fitted by four models such as pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. Among them, the adsorption of chromium (VI) was more inclined to the pseudo-first-order model (Radj2 = 0.9230). Then, the isotherm data were fitted by Langmuir and Freundlich models. The results indicated that Langmuir isotherm was the excellent match model (Radj2 = 0.9827). It belongs to a monolayer adsorption, and the maximum adsorption capacity was 95.92 mg·g−1. Subsequently, the thermodynamic parameters of the adsorption were calculated as follows: enthalpy change (ΔHθ) was −8.583 kJ·mol−1, entropy change (ΔSθ) was −8.243 J·mol−1 K−1, and the Gibbs function change (ΔGθ) was less than zero in the temperature range of 288–328 K, indicating that the reaction was spontaneous. Finally, both the spectra of infrared and XPS supported the adsorption mechanism that belonged the ion exchange. The spectra of XRD and SEM images shown that the structure of Cu (I)-MOF remained stable for at least 3 cycles. In conclusion, Cu (I)-MOF material has a high adsorption capacity, good water stability, low cost, and easy to prepare in large quantities in practical application. It will be a promising adsorbent for the removal of Cr (VI) from water

Contribution of pyrethroids in large urban rivers to sediment toxicity assessed with benthic invertebrates Chironomus dilutus: A case study in South China

The importance of pyrethroids as potential stressors to benthic organisms has gradually become evident in urban creeks; however, the occurrence and toxicity of sediment-associated pyrethroids are rarely studied in large rivers. In this context, 10 sediments from a large urban river (Guangzhou reach of the Pearl River in China) were assessed for pyrethroid occurrence and sediment toxicity to the benthic invertebrate Chironomus dilutus. One half of the sediments exhibited lethality to C. dilutus in a 10-d exposure and all surviving midges showed significant change of enzymatic activity. Moreover, mortality occurred during a 20-d exposure for all the sediments, in accordance with the high hazard quotients to benthic species estimated from pyrethroid residues in sediment. Pyrethroids were detectable in all sediments with the concentrations ranging from 2.43 to 61.2ng/g dry weight, and permethrin and cypermethrin dominated pyrethroid composition. Acute toxic units for pyrethroids ranged from 0.03 to 0.56 (cypermethrin accounted for 13-81%) and showed a direct relationship with sediment mortality among the midges. This is consistent with the studies on small creeks in Guangzhou in which sediment-bound cypermethrin was found as a main stressor to benthic invertebrates. Comparatively, sediment toxicity and pyrethroid residues in large rivers were significantly lower than those in nearby creeks (urban tributaries). The difference may be partially explained by differing flow rates and water-carrying capacity among waterbodies at different scales; further validation is required. Overall, extensive use of pyrethroids has caused a threat to benthic species not only in small creeks but also in large rivers. Environ Toxicol Chem 2017;36:3367-3375. (c) 2017 SETA

Facile and Safe Synthesis of Novel Self-Pored Amine-Functionalized Polystyrene with Nanoscale Bicontinuous Morphology

The chloromethyl-functionalized polystyrene is the most commonly used ammonium cation precursor for making anion exchange resins (AER) and membranes (AEM). However, the chloromethylation of polystyrene or styrene involves highly toxic and carcinogenic raw materials (e.g., chloromethyl ether) and the resultant ammonium cation structural motif is not stable enough in alkaline media. Herein, we present a novel self-pored amine-functionalized polystyrene, which may provide a safe, convenient, and green process to make polystyrene-based AER and AEM. It is realized by hydrolysis of the copolymer obtained via random copolymerization of N-vinylformamide (NVF) with styrene (St). The composition and structure of the NVF-St copolymer could be controlled by monomeric ratio, and the copolymers with high NVF content could form bicontinuous morphology at sub-100 nm levels. Such bicontinuous morphology allows the copolymers to be swollen in water and self-pored by freeze-drying, yielding a large specific surface area. Thus, the copolymer exhibits high adsorption capacity (226 mg/g for bisphenol A). Further, the amine-functionalized polystyrene has all-carbon backbone and hydrophilic/hydrophobic microphase separation morphology. It can be quaternized to produce ammonium cations and would be an excellent precursor for making AEM and AER with good alkaline stability and smooth ion transport channels. Therefore, the present strategy may open a new pathway to develop porous alkaline stable AER and AEM without using metal catalysts, organic pore-forming agents, and carcinogenic raw materials

Leachability and Anti-Mold Efficiency of Nanosilver on Poplar Wood Surface

Water-based antimicrobial agents, used in environmentally friendly applications, are widely used in wood protection industries. Furthermore, nanomaterials as antimicrobial agents, because of their biocidal component, huge specific surface area, and unique nanoscale effect, have attracted attention in the field of biodurability. We employed aqueous dispersed nano-silver with a diameter of 10 nm~20 nm to treat poplar wood and evaluated its leaching resistance and anti-mold effect on the wood surface. The results revealed that the higher the retention of the nano-silver, the stronger the protection efficiency of the wood surface against three molds (Aspergillus niger V. Tiegh, Penicillium citrinum Thom, and Trichoderma viride Pers. ex Fr); and the leachability of the nano-silver presented a slowly growing trend with the increase in the retention. When the wood surface attained a silver retention of 0.324 g·m−2, its anti-mold efficiency against Aspergillus niger V. Tiegh, Penicillium citrinum Thom, and Trichoderma viride Pers. ex Fr reached 80, 75, and 80%, respectively, which achieved or even exceeded the required standard value of effective mold inhibition (75%). Notably, the nano-silver leaching rate at this retention attained merely 4.75 %. The nanoparticle, well distributed on a wood surface, may promote sufficient contact with fungi as well as strong interaction with wood cell wall components, which probably contributed to the effective anti-mold efficiency and the leaching resistance. This study provided positive evidence for the anti-mold effect of nano-silver on wood surface