Roles of red mud-based biochar carriers in the recovery of anammox activity: characteristics and mechanisms.

Anaerobic ammonium oxidation (anammox) sludge is easily deactivated in the process of treating ammonia-laden wastewater. To investigate an effective recovery method, red mud-based biochar carriers (RMBC) were prepared and added to a deactivated anammox reactor; the operation of this reactor had been interrupted for 6 months with starvation and low temperature. The deactivated sludge with added RMBC was recovered rapidly after 31 days, with the specific anammox activity rapidly increasing to 0.84 g N/(g VSS∙day), and the recovery efficiency of nitrogen removal rate increased by four times compared to the unadded control. The granulation degree and extracellular polymeric substances secretion of the anammox sludge with the added RMBC were significantly higher than that of the control group. In addition, a large number of spherical anammox bacteria were observed moored at the porous channels of RMBC, and the copy numbers of functional genes of anammox bacteria were approximately twice that of the control group. Hence, RMBC is a potential sludge activator, and it can provide a "house" to protect anammox bacteria, enhance the metabolic activity and the agglomerative growth of anammox bacteria, and synergistically achieve rapid recovery of deactivated anammox sludge.

Association of dietary cholesterol and dyslipidemia in Chinese health examinees.

BACKGROUND: The association between dietary cholesterol consumption and dyslipidemia is still in controversy. The study aims to evaluate whether dietary cholesterol intake associated with dyslipidemia and its components in Chinese health examinees. METHODS: A large-scale cross-sectional study was conducted among health examinees of in Shaanxi province. Totally of 8358 participants (3677 male and 4681 female) were included. Dietary cholesterol intake was assessed by validated food frequency questionnaire. Multivariable regression and restricted cubic spline models were used to capture the linear and non-linear association between dietary cholesterol and dyslipidemia. RESULTS: A total of 2429 (29.1%) subjects were newly diagnosed of dyslipidemia, the prevalence was 29.2% in male and 27.7% in female. Mean intake of dietary cholesterol was 213.7 mg/day. After adjusting for all potential confounders including demographics information and lifestyles, higher cholesterol consumption was related to lower risk of dyslipidemia, the ORs (95% CIs) across Q2 to Q4 group were 0.87 (0.60-1.26), 0.80 (0.55-1.18) and 0.61 (0.41-0.91) in female. With further controlling for nutrients principal components, a null association was observed between dietary cholesterol and dyslipidemia and serum lipids, regardless of gender. Results of restricted cubic splines showed that the risk of dyslipidemia decreased slowly until around 300 mg/day in men and 200 mg/day in women, although the non-linear association was not significant. CONCLUSIONS: The study suggested that dietary cholesterol consumption was not associated with dyslipidemia or serum lipids in Chinese health examinees, although a decreased risk was observed before the threshold points.

Up-flow anaerobic column reactor for sulfate-rich cadmium-bearing wastewater purification: system performance, removal mechanism and microbial community structure.

This study constructed an up-flow anaerobic column reactor fed with synthetic sulfate-rich cadmium (Cd(II))-bearing wastewater, for investigating its Cd(II) removal performance and mechanism. Long-term experiment results manifest that introducing Cd(II) into influent led to an enhanced sulfate removal but did not increase the effluent sulfide concentration, implying the CdS formation. When influent Cd(II) concentration was shifted from 50 to 100 mg/L, the median Cd(II) removal rate was increased from 13.6 to 32.2 mg/(L·d). Batch tests indicate that the uptake and sequestration function of anaerobes merely led to a small portion of Cd(II) removal. A majority of aqueous Cd(II) (86.3%) was eliminated by precipitation reactions. The generated precipitates were found to be dominantly presented in carbonate, Fe-Mn oxide, sulfide bound and residue forms, which account for 92.6-93.9% of total Cd content of sludge obtained at diverse operation phases. The crystallographic CdS (i.e., residue fraction) particles have nano-scale sizes, and the relatively high atomic ratio of S to Cd was likely due to the adsorption/deposition of other sulfides. The dominant sulfate-reducing bacteria (SRB) were recognized as Desulfurella, Desulforhabdus and Desulfovibrio, and the primary competitor with them for substrate utilization were identified to be methanogens.

Nitrogen removal from ammonium- and sulfate-rich wastewater in an upflow anaerobic sludge bed reactor: performance and microbial community structure.

Autotrophic ammonium removal by sulfate-dependent anaerobic ammonium oxidation (S-Anammox) process was studied in an upflow anaerobic sludge bed reactor inoculated with Anammox sludge. Over an operation period of 371 days, the reactor with a hydraulic retention time of 16 h was fed with influent in which NH4+ concentration was fixed at 70 mg N L-1, and the molar ratio of NO2-:NO3-:SO42- was 1:0.2:0.2, 0.5:0.1:0.3 and 0:0:0.5 in stages I, II and III, respectively. As the NO2- in influent was entirely replaced by SO42-, the NH4+ removal rate was 31.02 mg N L-1 d-1, and the conversion rate of SO42- was 8.18 mg S L-1 d-1. On grounds of the high NH4+:SO42- removal ratio (8.67:1), the S2- accumulation and pH drop in effluent, as well as the analysis results of microbial community structure, the S-Anammox process was speculated to play a dominant role in stage III. The NH4+ over-transformation was presumably as a consequence of the cyclic regeneration of SO42-. Concerning the microbial characteristics in the system, the Anammox bacteria (Candidatus Brocadia), sulfate-reducing bacteria (SRB) (Desulfatiglans and Desulfurivibrio) and sulfur-oxidizing bacteria (SOB) (Thiobacillus) in biomass was enriched in the case of without addition of NO2- in influent. Sulfate reduction driven ammonium anaerobic oxidation was probably attributed to the coordinated metabolism of nitrogen- and sulfur-utilizing bacteria consortium, in which Anammox bacteria dominates the nitrogen removal, and the SRB and SOB participates in the sulfur cycle as well as accepts required electrons from Anammox bacteria through a direct inter-species electron transfer (DIET) pathway.

An environmentally-benign flow-batch system for headspace single-drop microextraction and on-drop conductometric detecting ammonium.

This work presents a lab-made automatic flow-batch system for headspace single-drop microextraction and on-drop conductometric sensing ammonium. Sample and NaOH solution are simultaneously pumped into a reaction chamber (RC), where ammonium is converted to ammonia by raising pH. The converted ammonia then diffuses into the headspace of the RC, and reacts with a 100 mM boric acid drop. The conductivity of the drop is measured by an on-drop conductivity probe, which is made by two stainless-steel contacting electrodes. The result shows that the increasing rate of conductivity has a linear relationship to the ammonium concentration in sample (R2 = 0.9945). This method has a linear range up to 400 µM, a limit of detection 2.8 µM, a relative standard deviation of 3.0% (200 µM, n = 10) and carryover coefficient 0.028. Measurements of river waters, lake waters and wastewaters have been demonstrated. The recoveries have achieved from 99.0 to 114%. This method avoids using of harmful or odorous reagents and follows the concept of green chemistry.

Manganese accumulation and plant physiology behavior of Camellia oleifera in response to different levels of nitrogen fertilization.

Manganese (Mn) pollution in soil, especially around the mining areas, is a severe problem in China. Seeking for effective remediation methods for Mn-contaminated soil is therefore urgent and necessary. Camellia oleifera (C. oleifera) is one of the world's four major woody oil plants, which is widely cultivated in subtropical acidic soils for oil production and has become an important economic and ecological resource in Guangxi Province. Nitrogen (N) is one of the most common limiting factors for plant growth and development in soils. We carried out this study to evaluate the effects of different N fertilization levels (0, 100, 300 and 500 mg kg-1) on the morphological and physiological characteristics of C. oleifera in two soils with different Mn-contamination degrees. The results indicate that N fertilization affected the plant growth and the content of photosynthetic pigments, while C. oleifera accumulated great amounts of Mn in both soils. However, the plant biomass reduced significantly at the high-level N fertilization (≥300 mg kg-1), and the oxidative stress was stimulated under Mn contamination. As a comparison, the plant biomass remained unaffected at the low-level N fertilization (100 mg kg-1), and the ascorbate peroxidase (APX) activity in C. oleifera leaves were enhanced to alleviate the oxidative stress and therefore protecting the plant from Mn contamination. Meanwhile, plants supplemented with a low-level of N fertilizer (100 mg kg-1) had appropriate antioxidant enzyme and nonenzymatic antioxidant activities, which indicates that this was favorable growth conditions for C. oleifera. Thus, the recommended N fertilization level for maintaining plant biomass and increasing Mn accumulation in plant is 100 mg kg-1 N; at which level the efficiency of Mn phytoremediation by C. oleifera can be further enhanced.

A needle-to-post air discharge ion source in tandem with FAIMS system.

A needle-to-post ionization source was designed for high-field asymmetric waveform ion mobility spectrometry (FAIMS). The needle-to-post ion source includes asymmetric electrode comprised of a copper post with a diameter of 2 mm and a stainless-steel needle with 200-µm tip radius and length of 28 mm. With the discharge voltage of -5.6 kV and N2 gas flow, glow discharge was realized at atmospheric pressure. The mass spectra of ionized ions about acetone, ethanol and ethyl acetate were gotten by Thermo Scientific LTQ XL ion trap mass spectrometer (MS). The MS experimental results show that the main ions are protonated and dimer ions. The needle-to-post ion source was mounted on the FAIMS system and FAIMS spectra are gotten successfully. Separation of p-xylene, o-xylene and m-xylene was realized. It shows that the needle-to-post electrode could be used as the ion source in a FAIMS system.

Design, Fabrication and Mass-spectrometric Studies of a Micro Ion Source for High-Field Asymmetric Waveform Ion Mobility Spectrometry.

A needle-to-cylinder electrode, adopted as an ion source for high-field asymmetric ion mobility spectrometry (FAIMS), is designed and fabricated by lithographie, galvanoformung and abformung (LIGA) technology. The needle, with a tip diameter of 20 µm and thickness of 20 µm, and a cylinder, with a diameter of 400 µm, were connected to the negative high voltage and ground, respectively. A negative corona and glow discharge were realized. For acetone with a density of 99.7 ppm, ethanol with a density of 300 ppm, and acetic ether with a density of 99.3 ppm, the sample gas was ionized by the needle-to-cylinder chip and the ions were detected by an LTQ XL™ (Thermo Scientific Corp.) mass spectrometer. The mass spectra show that the ions are mainly the protonated monomer, the proton bound dimer, and an ion-H2O molecule cluster. In tandem with a FAIMS system, the FAIMS spectra show that the resolving power increases with an increase in the RF voltage. The obtained experimental results showed that the micro needle-to-cylinder chip may serve as a miniature, low cost and non-radioactive ion source for FAIMS.

Association between polycystic ovary syndrome and the risk of stroke and all-cause mortality: insights from a meta-analysis.

Many epidemiologic literatures have investigated the link between PCOS and long-term stroke risk and all-cause mortality, but the results are surprisingly conflicting. A meta-analysis was performed to examine the link between polycystic ovary syndrome (PCOS) and the risk of stroke, death from any cause, and assessed whether BMI might explain a higher risk of stroke. We searched the PUBMED, EMBASE, and Cochrane Library databases with no restrictions. Nine Cohort studies were identified, involving a total of 237,647 subjects. Compared with those without PCOS, subjects with PCOS were significantly associated with a increased risk of developing stroke (OR = 1.36; 95% CI 1.09-1.70; p = .007). However, no significant association was observed between PCOS and all-cause death (OR = 1.21; 95% CI 0.88-1.66; p = .25). Moreover, after pooling the five studies with risk estimates adjusted for BMI, the association between PCOS and stroke was slightly attenuated, although the odds ratios did not reach statistical significance (OR = 1.24; 95% CI 0.98-1.59). In conclusion, PCOS is associated with significant increased risk for stroke, while there is no consistent evidence to indicate that PCOS influences all-cause death outcomes. Increased BMI is an important contributor to the relationship between PCOS and stroke risk. Further study is needed to clarify which subgroups of subjects with the PCOS are at higher risk for stroke and should focus on developing reliable device for risk stratification.

Exposure to a chronic high-fat diet promotes atrial structure and gap junction remodeling in rats.

Obesity has been demonstrated to be linked to atrial fibrillation (AF) with atrial enlargement and tissue fibrosis. Long-term high calorie intake is the main reason for the prevalence of obesity. To investigate the possible causes of AF, such as chronic high-fat diet (HFD), and to identify the underlying mechanisms, the present study analyzed a variety of structural and gap junctional electrophysiological alterations in the atria of female rats fed an HFD. After consistent HFD feeding of female rats for 12 weeks, hematoxylin and eosin (H&E) and Masson's staining, RT-qPCR, western blotting, immunofluorescence and TUNEL staining were performed. In our study, approximately 3/5 of the HFD-fed rats (HFD-OB, n=13) displayed a significant increase in body weight, while the other 2/5 did not (HFD-NOB, n=8). In addition, the atrial weight of the HFD-OB and HFD-NOB rats was markedly heavier, as compared to the rats fed a normal diet (CT, n=20). According to the plasma lipid levels, both HFD-OB and HFD-NOB rats exhibited dyslipidemia. Furthermore, H&E staining revealed broadened interstitial space and myocyte disarray in atria of the HFD-fed rats (i.e., HFD-OB and HFD-NOB rats). Expression levels of atrial fibrosis relevant factors, transforming growth factor-ß1 and matrix metalloproteinase-2, were significantly upregulated in the HFD-fed rat atria. In addition, we found a gap junction remodeling with distinct alterations in expression and distribution of connexin 40 (Cx40) and Cx43 in the HFD-fed rat atria. Moreover, a modest increase in apoptotic cell death in both the HFD-OB and HFD-NOB rat atria was detected. Taken together, our findings demonstrated that the impact of chronic HFD on atria displayed in the diet-induced obese rats was observed in HFD-fed rats in the absence of obesity as well.

An Integrated Microfabricated Chip with Double Functions as an Ion Source and Air Pump Based on LIGA Technology.

The injection and ionization of volatile organic compounds (VOA) by an integrated chip is experimentally analyzed in this paper. The integrated chip consists of a needle-to-cylinder electrode mounting on the Polymethyl Methacrylate (PMMA) substrate. The needle-to-cylinder electrode is designed and fabricated by Lithographie, Galvanoformung and Abformung (LIGA) technology. In this paper, the needle is connected to a negative power supply of -5 kV and used as the cathode; the cylinder electrodes are composed of two arrays of cylinders and serve as the anode. The ionic wind is produced based on corona and glow discharges of needle-to-cylinder electrodes. The experimental setup is designed to observe the properties of the needle-to-cylinder discharge and prove its functions as an ion source and air pump. In summary, the main results are as follows: (1) the ionic wind velocity produced by the chip is about 0.79 m/s at an applied voltage of -3300 V; (2) acetic acid and ammonia water can be injected through the chip, which is proved by pH test paper; and (3) the current measured by a Faraday cup is about 10 pA for acetic acid and ammonia with an applied voltage of -3185 V. The integrated chip is promising for portable analytical instruments, such as ion mobility spectrometry (IMS), field asymmetric ion mobility spectrometry (FAIMS), and mass spectrometry (MS).

[Phase separation characteristics of an anaerobic baffled reactor treating organic wastewater containing sulphate].

Phase separation characteristics of anaerobic baffled reactor (ABR) treating organic wastewater containing sulphate were investigated in a 5-compartment ABR with an effective volume of 32 L. During a start-up experiments of 132 days, the chemical oxygen demand (COD) and sulphate (SO4(2-)) removal efficiency, volatile fatty acid (VFA) and sulfide (S2-) distribution in each compartment were measured. The microbiology communities of granular sludge were also investigated by scanning electronic microscope (SEM). The experimental results showed that low influent loading and low increase are the keys to start-up of ABR. The volumetric loading rates of COD and SO4(2-) increased stage and stage from 1.5 kg x (m3 x d)(-1) to 3.3 kg x (m3 x d)(-1) and from 0.07 kg x (m3 x d)(-1) to 0.18 kg x (m3 x d)(-1) for 132d, and achieved a stable state that resulted in 95% COD and 85% SO4(2-) removal. COD had the trend of decreasing with compartments along flow direction, it's removal rate in compartment 1, 4 and 5 took the large proportion in total COD removal rate, and sulphate removal rate in the initial three compartments took the large proportions in the total sulphate removal rate. The VFA and S2- concentrations were high in the initial three compartments and obviously declined in the final two compartments. With the loading rate increase, the proportion of COD and SO4(2-) removal rates in the final room increased, the highest and the lowest point of VFA and S2- concentrations were gradually moved to hind room. The SEM observation indicated microbiology communities of granular sludge in each compartment were cooperative and specific, it showed that the acidogenic phase and methanogenic phase, sulfate-reducing phase and sulfur-producing phase were separated in the ABR.