Kinetic and reactivity of gas-phase reaction of acyclic dienes with hydroxyl radical in the 273-318 K temperature range.

As dienes contain two C[double bond, length as m-dash]C bonds, theoretically, they are much more chemically reactive with hydroxyl radical (˙OH) than alkenes and alkanes, and the reaction with ˙OH is one of the main atmospheric degradation routes of dienes during the daytime. In our work, rate coefficients of three types of acyclic dienes: conjugated as 3-methyl-1,3-pentadiene (3M13PD), isolated as 1,4-hexadiene (14HD), and cumulated as 1,2-pentadiene (12PD) reaction with ˙OH were measured in the temperature range of 273-318 K and 1 atm using the relative rate method. At 298 ± 3 K, the rate coefficients for those reactions were determined to be k3M13PD+OH = (15.09 ± 0.72) × 10-11, k14HD+OH = (9.13 ± 0.62) × 10-11, k12PD+OH = (3.34 ± 0.40) × 10-11 (as units of cm3 per molecule per s), in the excellent agreement with values of previously reported. The first measured temperature dependence for 3M13PD, 14HD and 12PD reaction with ˙OH can be expressed by the following Arrhenius expressions in units of cm3 per molecule per s: k3M13PD+OH = (8.10 ± 2.23) × 10-11 exp[(173 ± 71)/T]; k14HD+OH = (9.82 ± 5.10) × 10-12 exp[(666 ± 123)/T]; k12PD+OH = (1.13 ± 0.87) × 10-12 exp[(1038 ± 167)/T] (as units of cm3 per molecule per s). The kinetic discussion revealed that the relative position between these two C[double bond, length as m-dash]C could significantly affect the reactivity of acyclic dienes toward ˙OH. A simple structure-activity relationship (SAR) method was proposed to estimate the reaction rate coefficients of acyclic dienes with ˙OH.

Transformable ECM Deprivation System Effectively Suppresses Renal Cell Carcinoma by Reversing Anoikis Resistance and Increasing Chemotherapy Sensitivity.

Extracellular matrix (ECM) is crucial in various biological functions during tumor progression, including induction of anoikis resistance and cell adhesion-mediated drug resistance (CAM-DR). Fibronectin (FN) is a vital ECM component with direct regulatory effects on ECM-mediated anoikis resistance and CAM-DR, making it an attractive and innovative therapeutic target for depriving ECM in tumor tissue. Herein, an ECM deprivation system (EDS) is developed based on FN targeting self-assembly peptide for constructing nanofibers in the ECM of renal cell carcinoma (RCC), which contributes to: i) targeting and recognizing FN to form nanofibers for long-term retention in ECM, ii) reversing anoikis resistance via arresting the FN signaling pathway, and iii) serving as a drug-loading platform for sensitizing chemotherapy by ameliorating CAM-DR. The results reveal that EDS significantly reverses anoikis resistance of RCC cells by inhibiting the phosphorylation of FAK, a positive regulator of the FN signaling pathway. Meanwhile, EDS serves as a chemotherapy-sensitizer of cancer, exerting significant synergistic effects with doxorubicin (DOX). In vivo validation experiments show that EDS effectively suppresses metastasis and tumor growth with chemotherapy resistance. Collectively, the innovative EDS notably inhibits the tumor-promoting effect of ECM and may provide a novel approach for suppressing ECM and enhancing chemo-drug sensitivity.

Allelopathic effect of rhubarb extracts on the growth of Microcystis aeruginosa.

With its advantages of ecological safety, environmental affinity, and high selectivity, allelopathic technology has been widely developed for algae inhibition. However, obtaining effective allelochemicals and realizing their mechanism are difficult. In this paper, a Chinese herbal medicine, namely, Rheum palmatum L. (Chinese rhubarb), was utilized as a source of allelopathic substances for the first time. Four units of rhubarb organic extracts were collected to study the inhibition of growth, photosynthesis, proteins, and algal toxin of Microcystis aeruginosa. Results showed that the ethyl acetate, n-butanol, and aqueous phases of the rhubarb extracts have notable inhibitory effects. After a 16-day treatment, the four extracts reduced M. aeruginosa by 64.1%, 59.3%, 61.9%, and 7.2% with disruption of algal photosynthesis and protein synthesis and reduction of algal toxin.

Experimental study on cyanide-contaminated soil (China) treatment by leaching and decomposition.

The removal of cyanide compounds in soil by leaching was investigated in flask and column tests. All the experiments were conducted under alkaline conditions to prevent loss of hydrogen cyanide. Results showed that leaching progressed rapidly when the leaching temperature or the initial cyanide concentration was high. The obtained cyanide data in the flask test fitted an inner diffusion process, as described by a shrinking core model. In the batch column test, the cyanide concentration decreased from 44.06 to 9.86 mg/kg when the leaching intensity was 79 L/(m2 h) after 23.8 h leaching. The leaching process for the cyanide compounds was divided into two stages according to the batch column test despite the decrease in the leaching velocity as the cyanide concentration in soil declined. Cyanide removal in the batch column test was better than that in the flask test due to the higher gradient of cyanide concentration. The aqueous solution containing cyanide compounds was decomposed effectively by the hybrid process of ozone and UV rays. Furthermore, the leaching and decomposition of the soil and leaching wastewater were performed with a continuous column test with circulating leaching liquid. The cyanide compounds in the soil and wastewater were removed effectively.

Shift of microbial diversity and function in high-efficiency performance biotrickling filter for gaseous xylene treatment.

Xylene is the main component of many volatile industrial pollution sources, and the use of biotechnology to remove volatile organic compounds (VOCs) has become a growing trend. In this study, a biotrickling filter for gaseous xylene treatment was developed using activated sludge as raw material to study the biodegradation process of xylene. Reaction conditions were optimized, and long-term operation was performed. The optimal pH was 7.0, gas-liquid ratio was 15:1 (v/v), and temperature was 25 °C. High-throughput sequencing technique was carried out to analyze microbial communities in the top, middle, and bottom layers of the reactor. Characteristics of microbial diversity were elucidated, and microbial functions were predicted. The result showed that the removal efficiency (RE) was stable at 86%-91%, the maximum elimination capacity (EC) was 303.61 g·m-3·hr-1, residence time was 33.75 sec, and the initial inlet xylene concentration was 3000 mg·m-3, which was the highest known degradation concentration reported. Kinetic analysis of the xylene degradation indicated that it was a very high-efficiency-activity bioprocess. The rmax was 1059.8 g·m-3·hr-1, and Ks value was 4.78 g·m-3 in stationary phase. In addition, microbial community structures in the bottom and top layers were significantly different: Pseudomonas was the dominant genus in the bottom layer, whereas Sphingobium was dominant in the top layer. The results showed that intermediate metabolites of xylene could affect the distribution of community structure. Pseudomonas sp. can adapt to high concentration xylene-contaminated environments. Implications: We combined domesticated active sludge and reinforced microbial agent on biotrickling filter. This system performed continuously under a reduced residence time at 33.75 sec and high elimination capacity at 303.61 g·m-3·hr-1 in the biotrickling reactor for about 260 days. In this case, predomestication combined with reinforcing of microorganisms was very important to obtaining high-efficiency results. Analysis of microbial diversity and functional prediction indicated a gradient distribution along with the concentration of xylene. This implied a rational design of microbial reagent and optimizing the inoculation of different sites of reactor could reduce the preparation period of the technology.

Biodegradation of 5-chloro-2-picolinic acid by novel identified co-metabolizing degrader Achromobacter sp. f1.

Several bacteria have been isolated to degrade 4-chloronitrobenzene. Degradation of 4-chloronitrobenzene by Cupriavidus sp. D4 produces 5-chloro-2-picolinic acid as a dead-end by-product, a potential pollutant. To date, no bacterium that degrades 5-chloro-2-picolinic acid has been reported. Strain f1, isolated from a soil polluted by 4-chloronitrobenzene, was able to co-metabolize 5-chloro-2-picolinic acid in the presence of ethanol or other appropriate carbon sources. The strain was identified as Achromobacter sp. based on its physiological, biochemical characteristics, and 16S rRNA gene sequence analysis. The organism completely degraded 50, 100 and 200 mg L-1 of 5-chloro-2-picolinic acid within 48, 60, and 72 h, respectively. During the degradation of 5-chloro-2-picolinic acid, Cl- was released. The initial metabolic product of 5-chloro-2-picolinic acid was identified as 6-hydroxy-5-chloro-2-picolinic acid by LC-MS and NMR. Using a mixed culture of Achromobacter sp. f1 and Cupriavidus sp. D4 for degradation of 4-chloronitrobenzen, 5-chloro-2-picolinic acid did not accumulate. Results infer that Achromobacter sp. f1 can be used for complete biodegradation of 4-chloronitrobenzene in remedial applications.

[Biotransformation and safety of cotton stalk alkaline peroxide mechanical pulping waste liquor].

OBJECTIVE: We studied the conditions of culturing Bacillus subtilis SY1 to treat cotton stalk alkaline peroxide mechanical pulping waste water, and evaluated afterwards the safety of its release to plants and animals. METHODS: The culture conditions were optimized through single factor tests, including temperature, initial pH, oxygen, and inoculation size. We used rats and big ear rabbits to test the safety of treated waste water. RESULTS: The optimal condition was as follows: initial pH7.0, hydraulic retention time 30 h, temperature 30 degrees C, filling rate of aeration 16 L/h, the dosage of Bacillus subtilis SY1 0.8 g a liter water, and the stuffing volume accounting for 30% of the effective volume of the reactor. Under these culture conditions, the live spore number of Bacillus subtilis SY1 reached 6.27 x 10(9) CFU/mL. The removal rate of COD reached 70.4%. Results of the acute dermal toxicity test, dermal irritation test, eye irritation test and skin sensitization test after treated by the fermentation showed no clinical signs or changes conditions, and no deaths during the test period of 21 days. Animal body weight had a tendency to increase and had no abnormalities in the major organs, the Lethal Dose 50 (Abbreviated LD50) values was equal or greater than 10.5 g/(kg body weight) in acute dermal toxicity experiments. LD50 values were equal or greater than 2500 mg/(kg body weight) in dermal irritation experiments. No rabbits exhibited chemosis eye at any time during the test period. The results of skin sensitization test showed no erythema or edema. The skin sensitization value was less than 0.5. CONCLUSION: Pulping waste water of APMP cotton stalk fermented by Bacillus subtilis SY1 had reduced COD and no obvious toxicity to animals.

Aquamicrobium terrae sp. nov., isolated from the polluted soil near a chemical factory.

A Gram-negative, aerobic, non-motile bacterial strain hun6(T) isolated from the polluted soil near a chemical factory in northern Nanjing, China was investigated to clarify its taxonomic position. Growth of strain hun6(T) occurred between 10 and 45 °C (optimum, 30 °C) and between pH 6.0 and 8.0 (optimum, pH 7.0). No growth occurred at NaCl concentrations greater than 5 % (w/v). The 16S rRNA gene sequence analysis indicated that strain hun6(T) belongs to the genus Aquamicrobium. The sequence similarities of strain hun6(T) to other type strains of Aquamicrobium genus were all below 98.5 %. The presence of ubiquinone-10, the predominant fatty acid summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C19:0 cyclo ω8c, a polar lipid pattern with phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and phophatidylmonomethylethanoamine were in accord with the characteristics of the genus Aquamicrobium. The G+C content of the genomic DNA was determined to be 63.5 mol%. The results of DNA-DNA hybridization, physiological and biochemical tests and chemotaxonomic properties allowed genotypic and phenotypic differentiation of strain hun6(T) from all known Aquamicrobium species. Therefore, strain hun6(T) can be assigned to a new species of this genus for which the name Aquamicrobium terrae sp. nov. is proposed. The type strain is hun6(T) (= CICC 10733(T) = DSM 27865(T)).