Study on the efficacy and mechanism of treatment of manganese-containing wastewater by pulse-alternating current coagulation.

To assess the effectiveness and underlying mechanism of pulse-alternating current coagulation (PACC) for treating manganese-laden wastewater, we examined the influence of various parameters. Specifically, we investigated the impact of current density, initial pH, initial Mn2+ concentration, electrolyte concentration, and alternating current frequency on the removal efficacy. The removal mechanism was meticulously examined using an adsorption kinetics analysis, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectrum (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The findings indicated that the concentration of Re(Mn2+) was 99.09% under the specified conditions: j = 2.5 A·m-2, pH0 = 7, c0(Mn2+) = 50 mg·dm-3, f = 500 Hz, c0(NaCl) = 500 mg·dm-3 and t = 40 min. When Re(Mn2+) = 98%, the energy consumption (EEC) was significantly lower for PACC at 1.23 kWh·m-3, compared to 1.52 kWh·m-3 for direct current condensation (DCC). This indicated a reduction in EEC by 19.1% when using PACC over DCC. The adsorption process of Mn2+ by the iron sol adheres to the principles of pseudo-second order kinetics. The primary component of flocs generated in the PACC process is α-FeOOH. The mechanism of Mn2+ removal in the PACC process involved the synthesis of Mn oxides, the formation of metal hydroxide precipitates and adsorption by nano-iron sol. This study provides a theoretical basis and technical support for the application of PACC technology in the field of manganese-containing wastewater treatment.

Association between sedentary behavior and depression in US adults with chronic kidney disease: NHANES 2007-2018.

BACKGROUND: Depression increases the risk of adverse clinical outcomes in patients with chronic kidney disease. Physical activity has been shown to improve depressive symptoms in this population, but the relationship of sedentary behavior with depression has not been studied. In this study, we examined the relationship between sedentary behavior and depression in patients with chronic kidney disease. METHODS: This cross-sectional study included 5,205 participants aged ≥ 18 years with chronic kidney disease participating in the 2007-2018 National Health and Nutrition Examination Survey. Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9). Recreation activity, work activity, walking or cycling for transportation, and sedentary behavior were measured using the Global Physical Activity Questionnaire. A series of weighted logistic regression models were used to investigate the aforementioned relationship. RESULTS: The prevalence of depression among US adults with chronic kidney disease was 10.97% in our study. In addition, sedentary behavior was strongly associated with higher levels of depressive symptoms, as measured by the PHQ-9 (P < 0.001). In the fully adjusted model, we found that compared with participants who had shorter durations of sedentary behavior, participants who had the highest durations of sedentary behavior had 1.69 times (odd ratio 1.69, 95% confidence interval: 1.27, 2.24) greater risk of being clinically depressed. After adjusting for confounding factors, subgroup analyses showed that the association between sedentary behavior and depression still existed in all stratifications. CONCLUSION: We found an association between longer duration of sedentary behavior and more severe depression in US adults with chronic kidney disease; however, prospective studies with larger sample sizes are still needed to confirm the effects of sedentary behavior on depression in the chronic kidney disease population.

Effects of oral non-protein calorie supplements on nutritional status among maintenance hemodialysis patients with protein-energy wasting: a multi-center randomized controlled trial.

Protein-energy wasting (PEW) is prevalent in maintenance hemodialysis (MHD) patients, and is one of the major risk factors for poor outcomes and death. This study aimed to investigate the effects of non-protein calorie supplements on the nutritional status of MHD patients with PEW. MHD patients with PEW were enrolled in this multi-center, open-label, randomized controlled trial. Then, they were randomly assigned to the intervention group to receive the non-protein calorie supplements containing 280 kcal of energy every day for 6 months or the control group to complete all aspects of the study without receiving supplements. Patients in both groups received dietary counselling from dietitians. Data on nutritional assessments, anthropometric measurements, blood analysis and dietary recall were collected at the baseline and at six months from both groups. Statistical analyses were performed using analysis of covariance (ANCOVA) adjusted for sex and baseline values. Ninety-two MHD patients completed the study. A significant increase in the subjective global assessment (SGA) score was found in the intervention group compared with the control group (4.88 ± 1.41 vs. 4.40 ± 1.16, p = 0.044). The ratio of PEW patients (diagnosed with SGA ≤5) in the intervention group (61.2%) was also significantly lower than that in the control group (83.7%) (p < 0.001). Moreover, significant improvements in body mass index (20.81 ± 2.46 kg m-2vs. 19.51 ± 2.60 kg m-2, p < 0.001), nutrition risk screening 2002 (2.45 ± 1.40 vs. 3.12 ± 1.37, p = 0.038), mid-upper arm circumference (23.30 ± 2.78 cm vs. 21.75 ± 2.87 cm, p = 0.001), and mid-arm muscle circumference (20.51 ± 2.32 cm vs. 19.06 ± 2.92 cm, p = 0.005) were observed in the intervention group compared with the control group. Patients in the intervention group took in more dietary energy than the control group (26.96 ± 4.75 kcal per kg body weight per day vs. 24.33 ± 2.68 kcal per kg body weight per day, p < 0.001). In conclusion, non-protein calorie supplements may improve the nutritional status of MHD patients with PEW.

Association between the blood manganese (Mn) and hemoglobin in patients undergoing maintenance hemodialysis.

BACKGROUND AND AIMS: Manganese (Mn) and iron metabolism are closely related. Iron metabolism disorders often lead to anemia in patients undergoing maintenance hemodialysis (MHD). Here, we aimed to investigate the relationship between blood Mn and hemoglobin (Hb) in patients undergoing MHD. METHODS: Patients undergoing MHD in September 2019 were included in a cross-sectional study. Clinical and demographic data and blood samples were collected before hemodialysis sessions, and blood levels of Mn were measured by inductively coupled plasma mass spectrometry. Both multivariable linear and binary logistic regression analyses were performed to study the relationship between the blood Mn and Hb. RESULTS: A total of 144 patients undergoing MHD were enrolled in the study. The patients had a mean age of 64.33 ± 13.39 years, median vintage of 33.50 (16.25-57.50) months. Among them, 66 were females (45.8%). The median blood Mn level was 13.55 µg/L (IQR:9.92-17.48). Ninety-nine patients were anemic (68.8%). The mean Hb level was 99.83 ± 19.68 g/L. The patient group with high blood Mn had a high proportion of females, and these patients had high levels of RBC, hemoglobin, Hct, UIBC, serum TCHOL, and serum LDL, yet short dialysis vintage, low prevalence of anemia, low levels of serum ferritin, serum iron, and TSAT. Following adjustment for confounding factors, we found that low blood Mn level was independently associated with lower Hb level and anemia in patients undergoing MHD by multivariate linear and multivariate binary logistic regression, respectively, in different models. CONCLUSION: Whilst our study showed that high levels of blood Mn were independently associated with high hemoglobin in patients undergoing MHD, further multicenter studies with large sample sizes are still required.

High Blood Cu/Zn Ratio is Associated with Nutritional Risk in Patients Undergoing Maintenance Hemodialysis.

Patients undergoing maintenance hemodialysis (MHD) are at risk of an imbalance of copper and zinc homeostasis. We hypothesized that there is an association between the blood copper-zinc (Cu/Zn) ratio and nutritional status in these patients. For this cross-sectional study, blood samples were collected from patients undergoing MHD at Guangzhou Red Cross Hospital in September 2019. Zinc and copper levels were measured using inductively coupled plasma mass spectrometry. The seven-point subjective global assessment (SGA), nutritional risk screening 2002 (NRS2002), and geriatric nutritional risk index (GNRI) were used to evaluate the overall nutritional status. We enrolled 144 MHD patients (men:women = 78:66), with an average age of 64.33 ± 13.39 years and a median dialysis vintage of 33.50 (16.25-57.50) months. Patients with a higher blood Cu/Zn ratio had lower levels of hemoglobin, blood zinc, serum prealbumin, albumin, and creatinine as well as low SGA and GNRI scores, but higher modified Charlson comorbidity index score, serum C-reactive protein level, interleukin-6 level, blood copper level, and NRS2002 score (all p < 0.05). After adjustment for confounding factors in multivariable models, a high blood Cu/Zn ratio was independently associated with nutritional risk defined by all nutritional parameters (SGA, NRS2002, and GNRI). Prospective studies with larger sample sizes are warranted to confirm these results.

Removal of phosphorus in wastewater by sinusoidal alternating current coagulation: performance and mechanism.

The effects of initial total phosphorus (TP) concentration, current density, conductivity and initial pH value on the removal rate of TP and energy consumption, as well as the behaviour and mechanism of phosphorus removal, were investigated by sinusoidal alternating current coagulation (SACC). The flocs produced by SACC were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy FTIR and X-ray photo electron spectroscopy. The thermodynamic and kinetic behaviours of phosphorus removal by iron sol adsorption were also studied in detail. In a self-made SACC reactor equipped with five sets of parallel iron electrodes spacing 10 mm, the removal rate of TP reached 90.9% for a pH 7.0 wastewater with 5 mg dm-3 TP (κ = 800 µS cm-1) after being treated for 60 min by applying 2.12 mA cm-2 sinusoidal alternating current. Compared with direct current coagulation (DCC), SACC exhibits a higher removal efficiency of phosphorus due to the stronger adsorption of the produced flocs. It was found that the adsorption in the SACC process follows pseudo-second-order kinetic with the involvement of the intra-particle model. The adsorption of iron sol to phosphorus was an endothermic and spontaneous process, and its adsorption behaviour can be characterized with Langmuir and Redlich-Peterson isothermal adsorption models. SACC may be employed for the treatment of more complex wastewater combined with biological and/or electrochemical techniques.

Association Between the Blood Copper-Zinc (Cu/Zn) Ratio and Anemia in Patients Undergoing Maintenance Hemodialysis.

Copper (Cu) and zinc (Zn) imbalances are common in dialysis patients. This study aimed to investigate the relationship between the blood Cu/Zn ratio and anemia in patients undergoing maintenance hemodialysis (MHD) treatment. This cross-sectional study included patients undergoing MHD at our center in September 2019. Clinical and demographic data and blood samples were collected before the hemodialysis sessions, and the blood levels of Zn and Cu were measured by inductively coupled plasma mass spectrometry. Multivariable linear and binary logistic regression analyses were performed to study the relationship between blood Cu/Zn ratio and anemia. A total of 144 MHD patients were enrolled in this study. The patients had a mean age of 64.33 ± 13.39 years, a median dialysis vintage of 33.50 (16.25-57.50) months, with 66 being females (45.8%). The median blood Cu/Zn ratio was 15.55 (interquartile range: 12.47-20.31). Anemia was present in 99 patients (68.8%). Groups with higher hemoglobin levels had decreased blood Cu/Zn ratios (p < 0.05). After adjustments for confounding factors, higher blood Cu/Zn ratios were independently associated with lower hemoglobin levels and anemia in MHD patients based on multivariate linear and multivariate binary logistic regression, respectively, in different models. Our study found that the blood Cu/Zn ratio is independently associated with anemia in MHD patients, but prospective multicenter studies with larger sample sizes are still needed to determine the appropriate cutoff values for blood zinc, blood copper, and blood Cu/Zn levels in this patient population.