Micro-aeration and low influent C/N are key environmental factors for achieving ANAMMOX in livestock farming wastewater treatment plants.

Anaerobic ammonium oxidation (ANAMMOX)-mediated system is a cost-effective green nitrogen removal process. However, there are few examples of successful application of this advanced wastewater denitrification process in wastewater treatment plants, and the understanding of how to implement anaerobic ammonia oxidation process in full-scale is still limited. In this study, it was found that the abundance of anaerobic ammonia-oxidizing bacteria (AnAOB) in the two livestock wastewater plants named J1 and J2, respectively, showed diametrically opposed trends of waxing and waning with time. The microbial communities of the activated sludge in the two plants at different time were sampled and analyzed by high-throughput sequencing of 16S rRNA genes. Structural equation models (SEMs) were used to reveal the key factors affecting the realization of the ANAMMOX. Changes in the concentration of dissolved oxygen and C/N had a significant effect on the relative abundance of anaerobic ammonia oxidation bacteria (AnAOB). The low concentration of DO (0.2∼0.5 mg/L) could inhibit the activity of nitrifying bacteria (NOB) to achieve partial oxidation of ammonia nitrogen and provide sufficient substrate for the growth of AnAOB, similar to the CANON (Completely Autotrophic Nitrogen removal Over Nitrite). Unlike CANON, heterotrophic denitrification is also a particularly critical part of the livestock wastewater treatment, and a suitable C/N of about 0.6 could reduce the competition risk of heterotrophic microorganisms to AnAOB and ensure a good ecological niche for AnAOB. Based on the results of 16S rRNA and microbial co-occurrence networks, it was discovered that microorganisms in the sludge not only had a richer network interaction, but also achieved a mutually beneficial symbiotic interaction network among denitrifying bacteria (Pseudomonas sp., Terrimonas sp., Dokdonella sp.), AnAOB (Candidatus Brocadia sp.) at DO of 0.2∼0.5 mg/L and C/N of 0.6. Among the top 20 in abundance of genus level, AnAOB had a high relative abundance of 27.66%, followed by denitrifying bacteria of 3.67%, AOB of 0.64% and NOB of 0.26%, which is an essential indicator for the emergence of an AnAOB-dominated nitrogen removal cycle. In conclusion, this study highlights the importance of dissolved oxygen and C/N regulation by analyzing the mechanism of ANAMMOX sludge extinction and growth in two plants under anthropogenic regulation of AnAOB in full-scale wastewater treatment systems.

Flavonoid-Rich Extract of Oldenlandia diffusa (Willd.) Roxb. Inhibits Gastric Cancer by Activation of Caspase-Dependent Mitochondrial Apoptosis.

OBJECTIVE: To evaluate the apoptosis and cycle arrest effects of Oldenlandia diffusa flavonoids on human gastric cancer cells, determine the action mechanisms in association with the mitochondrial dependent signal transduction pathway that controls production of reactive oxygen species (ROS), and evaluate the pharmacodynamics of a mouse xenotransplantation model to provide a reference for the use of flavonoids in prevention and treatment of gastric cancer. METHODS: Flavonoids were extracted by an enzymatic-ultrasonic assisted method and purified with D-101 resin. Bioactive components were characterized by high-performance liquid chromatography. Cell lines MKN-45, AGS, and GES-1 were treated with different concentrations of flavonoids (64, 96, 128, 160 µg/mL). The effect of flavonoids on cell viability was evaluated by MTT method, and cell nuclear morphology was observed by Hoechst staining. The apoptosis rate and cell cycle phases were measured by flow cytometry, the production of ROS was detected by laser confocal microscope, the mitochondrial membrane potential (MMP) were observed by fluorescence microscope, and the expression of apoptotic proteins related to activation of mitochondrial pathway were measured by immunoblotting. MKN-45 cells were transplanted into BALB/c nude mice to establish a xenograft tumor model. Hematoxylin and eosin staining was used to reveal the subcutaneous tumor tissue. The tumor volume and tumor weight were measured, the expression levels of proliferation markers proliferating cell nuclear antigen (PCNA) and Ki-67 were detected by immunohistochemistry, and the expression levels of CA72-4 were measured by enzyme linked immunosorbent assay. RESULTS: Oldenlandia diffusa flavonoids inhibited proliferation of MKN-45 and AGS human gastric cancer cells, arrested the cell cycle in G1/S phase, induced accumulation of ROS in the process of apoptosis, and altered MMP. In addition, flavonoids increased Apaf-1, Cleaved-Caspase-3, and Bax, and decreased Cyclin A, Cdk2, Bcl-2, Pro-Caspase-9, and Mitochondrial Cytochrome C (P<0.05). The MKN-45 cell mouse xenotransplantation model further clarified the growth inhibitory effect of flavonoids towards tumors. The expression levels of PCNA and Ki-67 decreased in each flavonoid dose group, the expression level of CA72-4 decreased (P<0.05). CONCLUSION: Flavonoids derived from Oldenlandia diffusa can inhibit proliferation and induce apoptosis of human gastric cancer cells by activating the mitochondrial controlled signal transduction pathway.

Acute stress of the typical disinfectant glutaraldehyde-didecyldimethylammonium bromide (GD) on sludge microecology in livestock wastewater treatment plants: Effect and its mechanisms.

Glutaraldehyde and didecyldimethylammonium bromide (GD) is a disinfectant widely used to prevent African swine fever (ASF) in livestock farms. However, the effect of residual GD on the activated sludge microbial ecology of receiving wastewater treatment plants (WWTPs) remains largely unknown. In this study, seven simulated systems were established to research the effects of GD on WWTPs and reveal the underlying mechanisms of microecological responses to GD at different concentrations. Both the nitrogen and carbon removal rates decreased with increasing GD concentrations, and nitrogen metabolism was inhibited more obviously, but the inhibition weakened with increasing stress duration. Microorganisms activated their SoxRS systems to promote ATP synthesis and electron transfer to support the hydrolysis and efflux of GD by producing a small number of ROS when exposed to GD at less than 1 mg/L. The overproduction of ROS led to a decrease of antioxidant and nitrogen removal enzyme activities, and upregulation of the porin gene increased the risk of GD entering the intracellular space upon exposure to GD at concentrations higher than 1 mg/L. Some denitrifiers survived via resistance and their basic capabilities of sugar metabolism and nitrogen assimilation. Notably, low concentrations of disinfectants could promote vertical and horizontal transfer of multiple resistance genes, especially aminoglycosides, among microorganisms, which might increase not only the adaptation capability of denitrifiers but also the risk to ecological systems. Therefore, the risks of disinfectants targeting ASF on ecology and health as well as the effects of disinfectant residuals from the COVID-19 epidemic should receive more attention.

Liquid chromatography-tandem mass spectrometry analysis for identification and quantification of antimicrobial compounds in distillery wastewater.

A high-resolution mass spectrometry (HR-MS) method was developed to analyze and identify small molecule compounds in distillery wastewater. According to identification confidence levels, 4 levels of compounds were identified. The five antimicrobial compounds (lactic acid, succinic acid, acetophenone, cinnamic acid, and phenyllactic acid), which shown in high concentrations, were at the highest level of confidence (level 1, confirmed structure). Thus, a rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to simultaneously quantify these antimicrobial compounds. The analysis was performed in the selective reaction monitoring (SRM) mode via the electrospray ionization (ESI) source operating in the negative ionization mode. Linear calibration curves were obtained over the concentration range of 50-1000.0 ng/mL for succinic acid, acetophenone, cinnamic acid, phenyllactic acid, and 375-7500 ng/mL for lactic acid. Precision and recovery of the analytes were all satisfactory (relative standard deviation < 10%). The validated method was successfully applied to quantitative analysis of the five antimicrobial compounds in distillery wastewater.•Analyze and identify 4 levels of small molecule compounds in distillery wastewater.•Simple method for quantification of five antimicrobial compounds.•Column temperature affected the lactic and succinic acid chromatographs significantly.

Microbial contamination control mechanism in lipid production using distillery wastewater and oleaginous yeast - Antimicrobial compounds in wastewater as a double-edged sword.

Microbial contamination and the high expense of sterilization are the key factors limiting the application of resource recovery in processes such as producing lipids (can be converted to biodiesel via transesterification) from wastewater. This study was conducted to study the succession of contaminating and indigenous microorganisms, analyze the mechanism and propose a control strategy for undesirable microorganisms in the non-sterile lipid production process using distillery wastewater and oleaginous yeast. In the early stage, indigenous microorganisms (Pichia, Saccharomyces, Acetobacter and Gluconobacter) were the main competitors. Based on antimicrobial experiment and analyses of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography mass spectrometry (GC-MS), the antimicrobial compounds (such as lactic acid 10,011-17,498 mg/L, succinic acid 210-325 mg/L and furfural 0.63-1.23 mg/L) combined with the low pH (3.2-3.8) in distillery wastewater played the primary role in the prevention of contaminating bacteria in this stage rather than the potential antimicrobial compounds from oleaginous yeast. Cinnamic acid (56-143 mg/L) was the main inhibitor against oleaginous yeast among the major antimicrobial compounds in wastewater. Its inhibition decreased when pH increased from 3.2 to 5.5. In the later stage, as the pH increased to over 7 during the culture, heterotrophic bacteria (Chryseobacterium and Sphingobacterium) with a relatively low tolerance for acidic conditions became the dominant undesirable microorganisms. Utilizing the antimicrobial activity of distillery wastewater combined with a high inoculum size and proper pH control could be effective for achieving dominant oleaginous yeast growth and improving lipid production in non-sterile conditions.

Potential reproductive toxicity of multi-walled carbon nanotubes and their chronic exposure effects on the growth and development of Xenopus tropicalis.

The increasing production and use of multi-walled carbon nanotubes (MWCNTs) will inevitably lead to discharge into the environment and exert negative effects on organisms. Many studies have focused on the toxicity of MWCNTs to aquatic animals, but little is known about their possible potential reproductive toxicity. In this study, 6 sexually mature Xenopus tropicalis were exposed to 0.5 and 2.5 mg/L MWCNTs suspensions for 56 days, and the toxicity of MWCNTs to the growth and reproduction of X. tropicalis were studied. The results showed that MWCNTs could inhibit the growth of body, including the testis, ovaries and fat of X. tropicalis. Histopathological section analysis showed that MWCNTs affected the formation of spermatogonia and oocytes, while had no notable effect on the heart or liver. MWCNTs would be accumulated in lungs of X. tropicalis inducing lung cannons. In addition, MWCNTs changed the microbial community structure and diversity of gut microbiota but did not change its abundance significantly. Moreover, MWCNTs could even decrease the fertilized and survival rate of X. tropicalis embryos. These results indicated that chronic exposure to MWCNTs would not only affect the growth and development of X. tropicalis, but also pose a potential risk on their reproduction.

Preparation of CeO2-doped carbon nanotubes cathode and its mechanism for advanced treatment of pig farm wastewater.

The effluent from conventional treatment process (including anaerobic digestion and anoxic-oxic treatment) for pig farm wastewater was difficult to treat due to its low ratio of biochemical oxygen demand to chemical oxygen demand (BOD5/CODCr) (<0.1). In the present study, electro-Fenton (EF) was used to improve the biodegradability of the mentioned effluent and the properties of self-prepared CeO2-doped multi-wall carbon nanotubes (MWCNTs) electrodes were also studied. An excellent H2O2 production (165 mg L-1) was recorded, after an 80-min electrolysis, when the mass ratio of MWCNTs, CeO2 and pore-forming agent (NH4HCO3) was 6:1:1. Results of scanning electron microscopy (SEM), transmission electron microscope (TEM) and x-ray photoelectron spectroscopy (XPS) showed that addition of NH4HCO3 and the doping of CeO2 could increase the superficial area of the electrode as well as the oxygen reduction reaction (ORR) electro-catalytic performance. The BOD5/CODCr of the wastewater from the first stage AO process increased from 0.08 to 0.45 and CODCr reduced 71.5% after an 80-min electrolysis, with 0.3 mM Fe2+ solution. The non-biodegradable chemical pollutants from the first stage AO process were degraded by EF. The non-biodegradable pollutants identified by LC-MS/MS in the effluent from AO process including aminopyrine, oxadixyl and 3-methyl-2-quinoxalinecarboxylic acid could be degraded by EF process, with the removal rates of 81.86%, 34.39% and 7.13% in 80 min, and oxytetracycline with the removal rate of 100% in 20 min. Therefore, electro-Fenton with the new CeO2-doped MWCNTs cathode electrode will be a promising supplement for advanced treatment of pig farm wastewater.

Accumulation and toxicity of multi-walled carbon nanotubes in Xenopus tropicalis tadpoles.

Multi-walled carbon nanotubes (MWCNTs), a common nanomaterial widely used and discharged in environment, might exert toxic effects on aquatic animals. In this paper, filter-feeding tadpole of Xenopus tropicalis was selected as bioindicator to study the exposure effects of MWCNTs suspensions of 0.5, 1, 2, 4 and 8 mg/L for 72 h. The results showed that the tadpoles could remain high survival rate of over 96.7% after 24 h's exposure to MWCNTs, but then decrease considerably, showing a significant time-dependent relationship. The LC50 was 2.53 mg/L for tadpoles exposed to MWCNTs for 72 h, when MWCNTs accumulated in their gills and digestive tracts. Moreover, the enrichment degree of MWCNTs in tadpole was related to exposure density than time. When MWCNTs suspension concentration was not over 1 mg/L, the heart rates increased significantly and then decreased continuously. The survivors from the toxicity test were transferred to fresh filtered water for recovery, but MWCNTs accumulated in the tadpoles' body didn't decrease obviously after 4 days. Although the maximum tadpoles survival rate of 80% was recorded in the exposure group of 0.5 mg/L MWCNTs, only 43.3% of the survivors could recover. Therefore, the final survival rate was negative related to the exposure densities of MWCNTs but positive related to the accumulating degree in tadpoles' body. The results demonstrated that MWCNTs exposure posed potential health risks to filter-feeding organisms by intake and accumulation in organs, which could provide useful information for the reasonable evaluation and scientific management of nanomaterials.

Spread of resistance genes from duck manure to fish intestine in simulated fish-duck pond and the promotion of cefotaxime and As.

Integrated culture is a widespread culture mode in South China, in which resistance genes (RGs) also spread in the circulation system with nutrients. Accordingly, the aim of the present study was to investigate the spread of RGs in a fish-duck pond and the RGs and bacterial community of fish intestines. Five fish tanks, including a control tank and four experimental tanks (duck manure, duck manure + cefotaxime, duck manure + As, and duck manure + cefotaxime + As), were tested for 100 days. The results showed that duck manure increased both the diversity and relative abundance of RGs in fish intestines, and the addition of stress factors (cefotaxime, As) increased the relative abundance of RGs by one to two orders of magnitude. The stress-inducing effect of cefotaxime was greater than that of As. Tetracycline resistance genes were more sensitive to stress factors and were the predominant RGs in fish intestines. RGs in duck manure preferentially spread from the water to biofilm and then to fish intestines, whereas co-stress of cefotaxime and As obviously promoted the spread of RGs to fish intestines. In comparison to the control tank, duck manure and stress factors significantly changed the bacterial community of fish intestines. Correlation analysis also revealed that arsB, MOX, tetA and sul1 were significantly correlated with intI1 (P < 0.01), which hinted a potentially dissemination risk of RGs in fish intestines. These findings provide a theoretical basis for further investigating the dissemination of RGs in integrated culture systems and for evaluating the ecological risk of antibiotic and As use in aquaculture.

Evolution and distribution of resistance genes and bacterial community in water and biofilm of a simulated fish-duck integrated pond with stress.

Integrated fish-duck pond is a common circular farming model in South China, besides, it is also hot-spot for the co-selection of antibiotic resistance genes (ARGs). The aim of this study was to investigate the effects of duck manure, As and cefotaxime on the bacterial community, and the evolution and distribution of ARGs and metal(loid) resistance genes (MRGs) in water and biofilm. Five groups of fish tanks included a control and four test groups. The experimental period lasted for 100 days. Six ARGs (CIT, DHA, EBC, FOX, MOX, TEM), two MRGs (arsB, arsC), and two integron genes (intI1, intI2) were tracked and detected in water and biofilm. The results showed that duck manure brought ARGs and MRGs into fish tanks. Stress factors (cefotaxime, As) increased the relative abundance of resistance genes, and this was positively correlated with stress concentrations. The biofilm was visible significantly at the end of stage 3, and the total relative abundance of resistance genes in biofilm was higher than water from stage 5 onwards. Evolution of AmpC ß-lactamase resistance genes was more obvious than MRGs, especially for MOX, which increased by 3 orders of magnitude. The abundance of Flavobacterium was higher in biofilm than in water. Moreover, correlation analysis showed that both arsB and MOX were significantly correlated with intI1 (p < 0.05), which suggested a potentially dissemination risk of resistance genes. This study provides a reference for health risk assessment in integrated aquaculture environment contaminated with duck manure, antibiotics and metalloids.

Effective removal of nitrate by denitrification re-enforced with a two-stage anoxic/oxic (A/O) process from a digested piggery wastewater with a low C/N ratio.

The combined process of a long-term biogas digester and double anoxic/oxic tanks is very commonly used in piggery wastewater treatment in South China, but the effluent does not meet the discharge standard of total nitrogen (TN) and chemical oxygen demand (CODCr) due to a low C/N ratio and insufficient organic carbon in digested piggery wastewater. Thus, a typical two-stage anoxic/oxic (A1/O1/A2/O2) process, which is widely used to treat digested piggery wastewater in the engineering application, was selected for study on a laboratory scale. Finally, the average removal efficiency of ammonia nitrogen in the two-stage AO process was 98.7%; at the same time, the content of nitrate increased to 180-190 mg/L. To further eliminate nitrogen, an anaerobic tank (S1), which was equipped the sludge that was acclimated in our laboratory by a high nitrogen loading slurry, was employed to treat the effluent from the two-stage AO process and contributed more than 70% removal efficiency. Further analysis showed that ammonia-oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in the O1 and O2 tanks together contributed to the conversion of ammonia nitrogen to nitrate, but the process of heterotrophic denitrification was inhibited in the A1 and A2 tanks because of insufficient carbon sources. In addition, most of the nitrate concentration was reduced under conditions with insufficient carbon sources, while Thauera-dominated the bacterial population in the sludge sample of the S1 tank.

A persistent-mode 0.5 T solid-nitrogen-cooled MgB2 magnet for MRI.

This paper presents construction details and test results of a persistent-mode 0.5-T MgB2 magnet developed at the Francis Bitter Magnet Lab, MIT. The magnet, of 276-mm inner diameter and 290-mm outer diameter, consisted of a stack of 8 solenoidal coils with a total height of 460 mm. Each coil was wound with monofilament MgB2 wire, equipped with a persistent-current switch and terminated with a superconducting joint, forming an individual superconducting loop. Resistive solder joints connected the 8 coils in series. The magnet, after being integrated into a testing system, immersed in solid nitrogen, was operated in a temperature range of 10-13 K. A two-stage cryocooler was deployed to cool a radiation shield and the cold mass that included mainly ~60 kg of solid nitrogen and the magnet. The solid nitrogen was capable of providing a uniform and stable cryogenic environment to the magnet. The magnet sustained a 0.47-T magnetic field at its center persistently in a range of 10-13 K. The current in each coil was inversely calculated from the measured field profile to determine the performance of each coil in persistent-mode operation. Persistent-current switches were successfully operated in solid nitrogen for ramping the magnet. They were also designed to absorb magnetic energy in a protection mechanism; its effectiveness was evaluated in an induced quench.

Evolution of corresponding resistance genes in the water of fish tanks with multiple stresses of antibiotics and heavy metals.

Abuse of antibiotics and heavy metals in aquaculture has been widely concerned and might aggravate the spread of resistance genes in environment. To investigate the occurrence and proliferation of antibiotic resistance genes (ARGs) and heavy metal resistance genes (HMRGs), three commonly used antibiotics (tetracycline, sulfanilamide, cefotaxime) and two heavy metals (Zn and Cu) were designed to add individually or jointly in nine fish tanks including five individual exposure tanks of tetracycline (tet), sulfanilamide (sul), cefotaxime (cef), Cu, Zn and four combination exposure tanks of tetracycline + sulfanilamide (tet + sul), tetracycline + sulfanilamide + cefotaxime (tet + sul + cef), tetracycline + sulfanilamide + Cu (tet + sul + Cu), tetracycline + sulfanilamide + Zn (tet + sul + Zn) as well as the control during the experiment period of 180 days. Nineteen ARGs (tetA, tetB, tetC, tetD, tetE, tetG, tetM, tetO, tetQ, tetS, tetW, tetX, tetY, sul1, sul2, sul3, blaDHA, blaMOX, blaFOX), two HMRGs (copA, czcA) and the class 1 integron gene (intI 1) in fish tanks water were investigated. The results showed that the residual rate of antibiotics and heavy metals ranged from 0.03% to 2.46% and 9.25%-52.97%, respectively, positively related to their original concentration and types. Tetracycline resistance genes were more sensitive to antibiotics and easier to be induced and developed than sulfanilamide resistance genes and AmpC ß-lactamase resistance genes. The total relative abundances of ARGs in combined stresses exposure tanks (tet + sul, tet + sul + cef, tet + sul + Cu, tet + sul + Zn) were about 1.01-1.55 times more than the sum of their individual ones. The co-selective effects of cefotaxime on the abundance and diversity of tetracycline resistance genes were stronger than Zn and Cu. Besides, multivariate correlation analysis revealed that tetO, tetQ, tetW and sul3 were in significant correlation with the concentrations of Cu and Zn (r = 0.882-0.992, p < 0.05 or p < 0.01). The significant correlations between tetO and intI1 (p < 0.01), tetW and intI1 (p < 0.05), and sul3 and intI1 (p < 0.05) hinted a potentially serious and undesirable dissemination risk of ribosomal protection proteins gene of ARGs.

Antibiotic resistance genes (ARGs) in duck and fish production ponds with integrated or non-integrated mode.

Antibiotic resistance genes (ARGs) are emerging micropollutants with environmental persistence. Aquaculture environments are considered as potential reservoirs for ARGs pollution and horizontal gene transfer (HGT). This study analyzed water and sediment from eight culture ponds (integrated culture: duck-fish pond; monoculture: duck pond and fish pond) and a control pond (without any aquaculture activity) in Zhongshan, South China. Seventeen types of ARGs were detected in all ponds, which conferring resistance to four classes of antibiotics including tetracycline (tetA, tetB, tetC, tetE, tetG, tetL, tetA-P, tetM, tetO, tetS, tetW and tetX), AmpC beta-lactamase products (EBC and FOX), sulfonamide (sul1 and sul2) and erythromycin (ermA), with class 1 integron (intI1) as motility gene. The total concentrations of detected ARGs in culture pond water were much higher than control (about 1.6-4.0 times). Integrated culture showed lowest absolute abundance of ∑ARGs in water (3.686 × 107 copies mL-1) and the highest in sediment (4.574 × 108 copies g-1). Monoculture ponds showed higher relative abundance of ∑ARGs both in water (fish pond: 0.5149) and sediment (duck pond: 0.4919). As the main contributor to the ARGs abundance and significant correlations with ∑tet, ∑ARGs and intI1 (P < 0.01), tetA was suggested to be a potential indicator for the abundance of tetracycline resistance genes in these classes of aquaculture modes in the Pearl River Delta. This study provides a case for the ARGs abundance in aquaculture and as a reference for the upcoming health risk assessment in aquatic environment.

Occurrence of antibiotic resistance genes in landfill leachate treatment plant and its effluent-receiving soil and surface water.

The antibiotic resistance genes (ARGs) from urban waste may spread to the environment with the discharge of leachate. Fifteen types of ARGs, including tetracycline, sulfonamides, AmpC ß-lactamase and the class 1 integron gene were detected in the samples from the largest leachate treatment plant (LTP) in Guangzhou and its effluent receiving bodies (soil and surface water). The results showed that ARGs in leachates were in high levels and varied with seasons. The abundance of ARGs in the influent from high to low was in the turn of summer, winter, spring. About 2 to 4 orders of magnitude of ARGs were eliminated by the whole leachate treatment process. The predominant ARGs in the receiving soil were intI1, tetB, sul2, tetA and tetX, while those in the receiving surface water were sul2, intI1 and sul1, and the concentrations of ARGs in the receiving bodies were higher than those in the other natural bodies by 1 to 2 orders of magnitude. In addition, the results of bivariate correlation analysis showed that the abundances of ARGs (tetC, tetW, sul1, sul2, intI1 and FOX) were in significant correlation with the concentrations of heavy metals (Cu, Zn, Ni and Cr) (p < 0.05). LTPs are more likely to be sources of ARGs than wastewater treatment plant (WWTP) and need to be focused on.

Construction and Persistent-Mode Operation of MgB2 Coils in the Range 10-15 K for a 0.5-T/240-mm Cold Bore MRI Magnet.

This paper presents construction and persistent-mode operation results of MgB2 coils for a 0.5-T/240-mm cold bore MRI magnet, wind-and-react with monofilament MgB2 wire at the MIT Francis Bitter Magnet Laboratory. The magnet, of respective inner and outer diameters of 276 and 290 mm and a total height of 460 mm, has center field of 0.5 T and current density of 11 kA/cm2. To limit the continuous length of Hyper Tech supplied MgB2 monofilament wire to ≤300 m, the magnet was divided into eight series-connected coils, each equipped with a persistent current switch and a superconducting joint. We have manufactured three coil modules. Before being tested as an assembly, each coil was tested individually to ensure its capacity to carry 100-A superconducting current in the range of 10-15 K. The three coils were then assembled, connected in series, and operated as a 3-coil assembly in persistent mode at nearly 100 A in the range of 10-15 K. We present results that include: 1) construction details; 2) component performances; and 3) a 3-coil assembly performance.

Lipid production by a mixed culture of oleaginous yeast and microalga from distillery and domestic mixed wastewater.

Lipid productivity by mixed culture of Rhodosporidium toruloides and Chlorella pyrenoidosa was studied using 1:1 mixed real wastewater from distillery and local municipal wastewater treatment plant with initial soluble chemical oxygen demand (SCOD) around 25,000 mg/L, initial cell density of 2×10(7) cells/mL (yeast) and 5×10(6) cells/mL (microalga), at 30 °C and 2.93 W/m2 (2000 lux, 12:12 h light and dark cycles). Lipid content and lipid yield achieved were 63.45±2.58% and 4.60±0.36 g/L with the associated removal efficiencies for SCOD, total nitrogen (TN), and total phosphorus (TP) at 95.34±0.07%, 51.18±2.17%, and 89.29±4.91%, respectively, after 5 days of cultivation without the pH adjustment. Inoculation of microalgae at 40 h of the initial yeast cultivation and harvesting part of inactive biomass at 72 h by sedimentation could improve both lipid production and wastewater treatment efficiency under non-sterile conditions.

Development of a 0.5-T/240-mm MgB2 MRI Magnet: Assembly Design and Module Coils.

This paper presents the latest results from our continued development of a 0.5-T/240-mm MgB2 MRI magnet at the MIT Francis Bitter Magnet Laboratory. Because we have successfully developed our superconducting joint technique with a monofilament MgB2 wire, manufactured by Hyper Tech Research, Inc. (Columbus, OH), we have decided to use a monofilament wire to wind our MgB2 MRI magnet. The magnet, comprising eight module coils, has a winding inner diameter of 276 mm, an outer diameter of 290 mm, and a total height of 460 mm. Each coil has its own persistent-current switch (PCS) and a superconducting joint. In order to guard against a few bad coils forcing the entire magnet to be inoperative, each coil will be heat-treated and tested individually. After eight coils are successfully operated, they will be assembled into an MRI magnet and series-connected with soldering joints between adjacent coils. The PCS in each coil is designed in such way that it will also serve as a detect-and-heat protection absorber when the magnet quenches over a small "localized" region: The conductor volume in the eight switches is designed to absorb the entire magnet energy while still remaining below 200 K. This paper reports 1) the design of the whole magnet and 2) the fabrication and test results of the two real-size test coils, with their PCSs and superconducting joints. The tests were conducted in gas helium in the temperature range of 10-15 K and in the self-field of the coils.

A 1.5-T/75-mm Magic-Angle-Spinning NMR Magnet.

We are currently working on a program to complete a 1.5-T/75-mm RT (room temperature) bore MAS (magic-angle-spinning) NMR (nuclear magnetic resonance) magnet. The MAS magnet comprises a z-axis 0.866-T solenoid and an x-axis 1.225-T dipole coil. The combination of the fields creates a 1.5-T field pointed at 54.74 degrees (magic angle) from the rotation (z) axis. During the 2nd year of this 3-year Phase I program, both coils have been wound and testing has begun. Some preliminary field mapping has been performed, and the design of the MAS magnet assembly has been completed. During the final year, the magnet assembly will be integrated into the cryogenic structure and tested at ~5.5 K in a solid nitrogen environment. Each coil will be energized separately, and the magnetic field will be mapped accurately. We expect a bare magnet uniformity of 100 ppm over a 10-mm diameter, 20-mm-long cylindrical volume. Then, using the field data, the uniformity will be improved to < 0.1.ppm with a combination of ferroshims and cryoshims. Final field measurement will be performed as the cryostat-magnet system is spun manually at ~0.1 Hz.

Magic-Angle-Spinning NMR Magnet Development: Field Analysis and Prototypes.

We are currently working on a program to complete a 1.5 T/75 mm RT bore magic-angle-spinning nuclear magnetic resonance magnet. The magic-angle-spinning magnet comprises a z-axis 0.866-T solenoid and an x-axis 1.225-T dipole, each to be wound with NbTi wire and operated at 4.2 K in persistent mode. A combination of the fields creates a 1.5-T field pointed at 54.74 degrees (magic angle) from the rotation (z) axis. In the first year of this 3-year program, we have completed magnetic analysis and design of both coils. Also, using a winding machine of our own design and fabrication, we have wound several prototype dipole coils with NbTi wire. As part of this development, we have repeatedly made successful persistent NbTi-NbTi joints with this multifilamentary NbTi wire.