Assessing combined toxic effects of tetracycline and P25 titanium dioxide nanoparticles using Allium cepa bioassay

• UVA pre-irradiation to TiO₂ NPs enhanced its toxicity toward plant A. cepa. • UVA TiO₂ NPs increased intracellular ROS, resulting in more cell damage. • Cell death enhanced cell permeability and increased uptake of NPs. • Being highly toxic (EC₅₀ = 0.097 µmol/L), TC did not increase ROS generation. • Even at a low dose, TC enhanced the toxic potential of TiO₂ NPs significantly. Usage of titanium dioxide nanoparticles (TiO₂ NPs) and tetracycline (TC) has increased significantly in the present era. This leads to their release and accumulation in the environment. Both the compounds, individually, can have adverse toxic effects on the plants. Their binary mixtures can increase this degree of damage. The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium cepa. Further, the toxicity of TiO₂ NPs upon UVA pre-irradiation was also measured. Results showed that UVA pre-irradiated NPs (UVA-TiO₂ NPs) had a significant decrease in cell viability than their non-irradiated counterparts (NI-TiO₂), denoting an increase in photocatalytic activity upon UVA pre-irradiation. Very low concentrations of TC (EC₁₀ = 0.016 µmol/L) mixed with TiO₂ NPs significantly increased the toxicity for both UVA-TiO₂ and NI-TiO₂ NPs. Intracellular ROS generation was significantly high for UVA-TiO₂ NPs. However, TC did not have any effects on ROS production. Both the compounds exhibited genotoxic potential in A. cepa. Different chromosomal abnormalities like anaphase bridges, telophase bridges, laggard chromosomes, binucleate cells, etc. were observed. The binary mixture of UVA-TiO₂ NPs and TC showed the highest chromosomal aberrations (64.0%±1.26%) than the mixture with NI-TiO₂ or the individual contaminants. This decreased significantly after recovery (46.8%±1.92%), denoting the self-repair processes. This study proved that UVA-TiO₂ NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC. This work will help to assess the risk of both compounds in the environment.     

活性粉末混凝土柱的抗震性能试验研究

活性粉末混凝土 (ReactivePowderConcrete ,简称RPC)是一种具有超高性能和超高强度的水泥基复合材料。本文首先论述了这一材料应用于结构抗震领域中的潜力 ,然后通过 4个小比例RPC矩形截面柱的拟静力试验 ,研究了RPC配筋柱的延性性能、滞回曲线及其破坏机理 ,分析了配箍率对RPC配筋柱延性的影响。     

Reactive Extrusion of Starch–Polyacrylamide Graft Copolymers Using Various Starches

Graft copolymers of polyacrylamide and various substrates were prepared by reactive extrusion in a twin screw extruder using ammonium persulfate as initiator. Substrates included unmodified starches (corn, waxy maize, wheat, and potato), cationic starches, dextrin, dextran, and polyvinyl alcohol (PVOH). The feed ratio of substrate to monomer was 2:1. Average conversion of monomer to polymer was 88.9% (±5.1%). Graft contents for the starch substrates were approximately 25% with grafting efficiencies of about 70%. Polyacrylamide graft molecular weights ranged from 317,000 to 769,000. Absorbencies at pH 7 for saponified graft copolymers prepared with unmodified starches were approximately 200 g/g and approximately 150 g/g for the cationic starches, dextran, and PVOH. In electrolyte solution (0.9% NaCl), absorbencies were in the range of 26–59 g/g, depending on substrate type. Saponified dextrin copolymers were essentially soluble with absorbencies of 6 g/g in water and 12 g/g in 0.9% NaCl.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Comparing the Growth Characteristics of Three Bacteria Involved in Degrading Rubbers

Three bacteria isolated for degradation of rubbers were compared for their growth characteristics derived from the Bradford protein assay and turbidity (optical density, OD) measurement. Both Alcaligenes xylosoxidans T2 and Pseudomonas aeruginosa GP10 were fast-growing bacteria while Nocardia corynebacterioides S3 was a slow grower utilizing rubber as the sole source of carbon and energy, but the extent of degradation was lower by the formers than the latter. A. xylosoxidans T2, P. aeruginosa GP10 and N. corynebacterioides S3 showed a typical sigmoidal growth pattern based on binding of Coomassie Brilliant Blue G250 to bacterial proteins and spectrophotometrical measurement at 600 nm. Both assays showed similar growth characteristics for all three bacteria in this study. Degradation of rubber was more pronounced by N. corynebacterioides S3 than either A. xylosoxidans T2 or P. aeruginosa GP10 during 70 days of incubation. Our results suggest that slow-growing bacteria may play a much greater role in degrading polymeric materials than was previously believed.     

微波诱导催化剂CuO/γ-Al_2O_3处理活性艳蓝的研究

采用均匀包裹沉淀法制得的CuO/γ-Al2O3催化剂,利用XRD对催化剂的物相结构进行了表征,并应用于微波诱导氧化工艺中,考察了催化剂投加量、微波功率、微波辐照时间等因素对活性艳模拟废水处理效果的影响。结果显示,在催化剂投加量为2g/L,微波功率为720W,辐照时间为3min的条件下,处理50mg/L的活性艳蓝脱色率可达到95.3%。     

HAP/UV催化降解活性艳蓝K-3R的研究

用化学沉淀法合成羟基磷灰石(HAP),并用XRD、SEM、FT-IR对其进行分析。以活性艳蓝K-3R为降解底物,研究HAP对其光催化降解性能。探讨了HAP煅烧温度、通气量、投加量、初始浓度等因素对光催化降解活性艳蓝K-3R效果的影响。研究表明化学沉淀法合成的HAP粒度均匀,HAP对活性艳蓝的吸附作用较强,30min之内即能达到吸附平衡,其对初始浓度为100mg/L的活性艳蓝的吸附率可达17.5%。适当的煅烧有利于提高HAP的催化活性,以200℃煅烧2h最佳。在投加量为4g/L,鼓气量为300L/h和pH=6的试验条件下,HAP(200℃)对初始浓度为100mg/L的活性艳蓝K-3R 3h的降解率达68%。降解反应动力学研究表明,HAP/UV光催化降解活性艳蓝K-3R的过程符合Langmuir-Hinshel-wood一级动力学方程,降解速率常数k随着活性艳蓝K-3R浓度的增大而减小。     

活性黑5高效脱色菌的分离鉴定和生长特性研究

通过富集和分离的方法,从处理印染废水的AAO工艺的厌氧反应器污泥中筛选出了一株对偶氮染料活性黑5具有较强脱色能力的高效菌株S8,并对其进行形态学观察和16S rDNA测序.此外,绘制了菌株S8的生长曲线,并在不同pH、温度、接种量、装液量和氮源的生长条件下对其进行培养,以OD600值为指标,考察这些因素对菌株S8生长的...     

Micelle dyeing with low liquor ratio for reactive dyes using dialkyl maleic acid ester surfactants

Micelle dyeing with low liquor ratio is novel fabric dyeing method for cleaner production. Preparation and interaction of dye-surfactant micelles using dibutyl maleic acid ester sodium sulfate surfactant were investigated by UV-Vis spectra. Dyeing properties of cellulose fabrics using micelle dyeing with low liquor ratio were discussed by color yields (K/S), color differences (ΔE), exhaustion (E), fixation (F) and reactivity (R) of three reactive dyes. The results show that reactive dye molecules could be solved in surfactant micelles and form stable dye-surfactant micelles. Micelles formed by dibutyl maleic acid ester sodium sulfate had good anti-agglomeration effect on dye solutions. Liquor ratio of micelle dyeing for cellulose fabrics could be reduced from 1:15 to 1:5. Leveling properties of three reactive dyes using micelle dyeing were good. The exhaustion, fixation and reactivity of all three dyes using micelle dyeing were similar with the conventional dyeing technology. Wet rubbing, washing and perspiration fastnesses of dyed samples using micelle dyeing were also good. Micelle dyeing with low liquor ratio can save a large amount of water and energy.     

酶法原位制备过氧乙酸对活性艳蓝KN-R氧化脱色的工艺

利用过水解酶催化合成过氧乙酸,过氧乙酸原位氧化活性艳蓝KN-R脱色.在单因子试验的基础上,通过正交优化试验确定活性艳蓝KN-R的最佳脱色条件为:在5 m L反应体系中,最适p H 5.0,加酶量为20 U·反应-1,乙酸乙酯对过氧化氢的摩尔比率为40∶1和活性艳蓝KNR的浓度为80 mg·L-1.在此条件下反应6 h后,活性艳蓝KN-R的脱色率为81.11%,24 h后的脱色率为91.96%.在50倍放大试验中,该工艺24小时的脱色率为84.55%.     

Evaluation of Abelmoschus esculentus (lady's finger) seed as a novel biosorbent for the removal of Acid Blue 113 dye from aqueous solutions

The use of a new biosorbent derived from Abelmoschus esculentus (A. esculentus) seed for the removal of Acid Blue 113 (AB113) in aqueous solutions was investigated in batch mode. Biosorption studies were carried out under varying operational parameters including initial pH, biosorbent dosage, contact time, initial dye concentration and temperature. The results indicated that the biosorption properties were strongly dependent on initial pH. Fourier transform infrared spectroscopy analysis revealed that hydroxyl, carboxylic and amide functional groups present on the biosorbent surface were involved in the dye removal process. Equilibrium data were best fitted by the Langmuir model. The maximum biosorption capacity was 169.9 ± 3.1 mg g⁻¹ at 25 °C and initial pH 5.5. The kinetic data were in good agreement with the pseudo-second-order kinetic model. The process was controlled by diffusion through boundary layer at the initial stage followed by intra-particle diffusion at the later stage. Thermodynamic evaluation showed that the process was endothermic and spontaneous. The present study suggests that A. esculentus seed with maximum biosorption capacity which compared well with values reported in the literature can be a potential biosorbent for AB113 dye removal.