Increase In Urea Concentration Research Articles

Investigating oral microbiome dynamics in chronic kidney disease and post-transplantation in continuous culture.

This study investigates dynamic changes in the oral microbiome associated with changes in salivary urea concentration, an important factor in chronic kidney disease (CKD). The in vitro system modeled increased urea concentrations and subsequent reductions post-transplantation. The study provides insight into the oral microbial shifts during different simulated clinical phases. Understanding these dynamics is crucial for advancing our comprehension of CKD-associated oral microbiome variations and their potential impact on patient well-being and recovery.

Subchronic Toxicity of Ethanol Extract of Mangosteen Rind (Garcinia Mangostana L.) on Kidney Function in Wistar Rats

Mangosteen (Garcinia mangostana L.) is a fruit that possesses antioxidant, antibacterial, antihistamine, anti-inflammatory, and antidiabetic properties. Before this, an acute toxicity test was conducted on the ethanol extract of mangosteen rind. However, further testing is required, specifically the subchronic toxicity test, to identify any hazardous effects that may not have been found in the previous study. The objective of this study is to evaluate the amount of toxicity based on the mortality rate, alterations in the relative weight of the kidneys, and changes in renal function as shown by levels of urea and creatinine. This study is an experimental investigation that employs the Post-test Only Control Group Design methodology, with a sample of 40 rats. The rats were categorized into two groups: the control group and the treatment group. The treatment group was divided into three subgroups, each receiving a dosage of 250 mg/kg body weight. The doses were 500 milligrams per kilogram and 1000 milligrams per kilogram of body weight, respectively. The control group received simply water and feed. The duration of the treatment was 28 days. Observations were conducted over 28 days, which involved monitoring animal mortality. On the 29th day, a surgical procedure was carried out to assess the comparative weight of the kidneys and collect blood samples for analyzing the levels of urea and creatinine. The findings demonstrated no mortality in the test subjects, although there was an elevation in the relative mass of the kidneys and an increase in urea concentrations. The increase in urea levels was observed in female rats using the Kruskal–Wallis test (P = 0.019). The study was further conducted using the post-hoc Mann–Whitney test. Control female rats exhibited notable disparities when administered dosages of 250 mg/kgBW and 500 mg/kgBW. The repeated administration of an ethanolic extract derived from the peel of the mangosteen fruit had a detrimental impact on the functioning of the kidneys, as evidenced by a rise in urea concentrations. Keywords: mangosteen, toxicity test, subchronic, kidney

Off-label letrozole for tubal pregnancy monotherapy is not an alternative to methotrexate: a prospective cohort study.

Inhibition of estradiol production by letrozole may interfere with physiological effects of progesterone necessary to maintain the pregnancy. Treatment of tubal pregnancy (TP) with letrozole would allow to avoid the disadvantages of methotrexate (MTX). The aim was to compare the effectiveness of letrozole with MTX in the management of TP. A prospective open-label cohort study was conducted among women with TP and increasing B-human chorionic gonadotropin (B-hCG) concentrations. MTX was administered in a single dose of 100 mg intravenously, while letrozole in a dose of 5 mg orally for 10 days. Blood parameters (B-hCG, hemoglobin, creatinine, urea, transaminases, bilirubin) were tested on days 0, 4 and 7. Out of 22 eligible women, 14 received MTX and received 8 letrozole. Mean age, lesion diameter, gestation age in the MTX vs letrozole arm were: 31 vs 32 years (p = 0.3), 13.2 vs 16.3 mm (p = 0.1), 7 + 1 vs 7 + 0 weeks (p = 0.6), respectively. In case of 4 women treated with letrozole and in 2 treated with MTX (4/8, 50% vs 2/14, 14.3%, p = 0.07) the treatment was unsuccessful. There were no significant differences in blood parameters on days 0, 4 and 7 between both arms, except for the increasing urea concentration in the letrozole arm (p = 0.01). Even though the results did not reach statistical significance, it is likely that a larger study sample would confirm the trend of letrozole being less effective. The results did not support the use of letrozole in the studied regimen as an alternative to MTX.

Biomineralization of heavy metals based on urea transport and hydrolysis within a new bacterial isolate, B. intermedia TSBOI

A newly isolated ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced calcite precipitation (MICP) which is a promising technique for the remediation of heavy metals in polluted environments. Brucella intermedia TSBOI achieved 90–100% removal of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. A distinctive feature lies in B. intermedia TSBOI’s capacity for the transport and hydrolysis of urea, considered to be critical for its strong urease activity. This study explored the mechanisms of this capacity at the genetic, molecular and protein levels through complete genome sequencing, molecular docking and enzymatic reaction kinetics. The results revealed that, for urea hydrolysis, B. intermedia TSBOI exhibited a comprehensive urease gene cluster, with the key gene ureC demonstrating an absolute expression level approximating to 4 × 104 copies/RNA ng under optimal conditions. Results also confirmed the strong spontaneous, energy-independent binding ability of it’s urease to urea, with the lowest Gibbs free energy binding site linking to the three amino acids, alanine, asparagine and serine. The urea transport gene yut presented and expressed, with the absolute expression enhanced in response to increasing urea concentrations. The significant positive correlation between ureC/yut expression levels and urease activity provided a theoretical basis for B. intermedia TSBOI's heavy metal bioremediation potential. Environmental ImplicationHeavy metals (Cu, Pb and Zn) were studied in this study. Heavy metals are hazardous due to their toxicity, persistence, and ability to bioaccumulate in living organisms. They can cause severe health issues, harm ecosystems, and contaminate air, water, and soil. A novel ureolytic bacteria, Brucella intermedia TSBOI, exhibited microbially induced carbonate precipitation capability was isolated which removed 90–100% of 1 mmol/L Cu2+/Pb2+/Zn2+ within 72 h. Its advantages in urea hydrolysis and transport facilitate the remediation of actual heavy metal contaminated environments.

Malignant insulinoma in dog: Case report

In this case report, a malignant insulinoma is described in a thirteen-year old male dog of the Yorkshire breed. Clinical examination revealed weakness and food intolerance manifested by nausea and diarrhoea. Biochemically, hypoglycaemia with hyperinsulinemia, elevated concentrations of selected liver enzymes, as well as lipase and continuously increasing urea concentrations were also found. Ultrasonography of the pancreas proved the presence of a severe hypoechoic, homogenous lesion approximately 1 cm in diameter; the liver was diffusely heterogeneous with the occurrence of small hypoechogenic lesions in the parenchyma. With regard to history, clinical symptoms, USG and laboratory findings, insulinoma was diagnosed. Post-mortem findings showed a large, multifocal greywhite tumour in the right pancreatic lobe and enlargement of the liver, with the occurrence of many miliary foci. The corresponding lymph nodes of the pancreas and liver were also enlarged. Histopathological examinations of the pancreas and liver revealed malignant insulinoma.

Membrane distillation of synthetic urine for use in space structural habitat systems

Abstract Low-energy separation of potable water from urine is an important area of research, particularly if humans hope to transcend their earth-bound origins. The high cost of water in rocket payloads means that it must be recycled and the byproducts of the crew used productively. Direct Contact Membrane Distillation (DCMD) can use low heat sources to separate water from urea, which can then be used as a plasticizer in regolith-based cement to make it more workable. In the present study, traditional cement curing was compared to vacuum curing for regolith-based cement where artificial urine, concentrated using DCMD, was added as a plasticizer. Increases in workability were found for increasing concentrations of urea. Porosity also tended to increase with increasing urea concentration. Surprisingly, Lunar Highlands Simulant regolith-based batches with urea that were cured under vacuum showed higher compressive strengths than those cured traditionally. No literature is available for DCMD use with urine, indicating that this research is novel and could have widespread applications, such as in desert environments or public urinals.

Comparative Effects of the Aqueous Extracts of Gongronema Latifolium and Tetrapleura Tetraptera on Serum Liver and Kidney Markers as well as Glucose Tolerance Test of Albino Rat

The study investigated the effect of aqueous extract of G. latifolum and T. tetraplura on serum liver and kidney markers as well as glucose tolerance test of albino Rat. A total of twenty five male albino rats were randomly grouped into five groups. Group 1 served as control, Group 2 and 4 received 200 and 400mg/kg G. latifolium respectively. Animals in Group 3 and 5 received 200mg/kg and 400mg/kg T. tetraplura respectively for 28days. Result for AST was significantly (P<0.05) higher in group 5 (43.000±3.033) when compared to the control group (30.400±2.158). ALT concentration was also significantly (P<0.05) in group 5 (34.600±1.077) when compared to the control (22.400±1.326). Result for kidney function parameters showed a significant (p˂0.05) increase in urea concentration of the group 5 (26.962±0.6340) when compared to the control (24.242±1.875) From the obtained results, it could be concluded that T. tetraplura could induce hepatotoxicity and nephrotoxicity. Also, from obtained results, the spices possess hypolipidemic and antioxidant activity. These ability of the spices to carry out these activities can be attributed to it rich phytochemical constituents.

THU112 Effect Of Protein Supplementation On Plasma Sodium Levels And Urinary Urea Excretion In Patients With Chronic Siad—A Monocentric Open-Label Proof-Of-Concept Study—The Treasure Study

Abstract Disclosure: S. Monnerat: None. C. Atila: None. F.E. Baur: None. M. Dickenmann: None. M. Christ-Crain: None. INTRODUCTION The syndrome of inappropriate antidiuresis (SIAD) is the most common cause of euvolemic hyponatremia. Besides fluid restriction, increasing free-water clearance is an effective treatment approach that can be achieved through osmotic diuresis by administering oral urea. However, oral urea has a very peculiar taste that impedes long-term compliance. Dietary proteins are metabolized into soluble excretable urea by the liver. We hypothesized that dietary protein could increase free water clearance through urea-induced osmotic diuresis and therefore aimed to investigate the effect of high-protein supplementation on plasma sodium levels in outpatients with chronic SIAD. METHODS This is an interim analysis of a monocentric open-label proof-of-concept trial conducted at the University Hospital of Basel since October 2021. Adult outpatients with chronic SIAD of any etiology were eligible. Patients received 90g protein daily for 7 days in the form of protein powder dissolved in a maximum of 1L of liquid of choice. After a wash-out period of at least a week, patients received 30g of oral urea daily for 7 days. Patients were asked to keep their baseline fluid intake unchanged throughout the study. The primary endpoint was the increase in sodium levels from baseline to the end of the 7-day protein supplementation. RESULTS Thirteen patients, 10 females and 3 males, with chronic SIAD were included. Median [IQR] age was 63 [61, 80] and the median [IQR] duration of hyponatremia was 33 months [12, 42]. At baseline, median [IQR] plasma sodium concentration was 130 mmol/L [129, 133]. Eight patients had mild hyponatremia (130-134 mmol/L), 4 had moderate hyponatremia (125-129 mmol/L), and 1 patient had profound hyponatremia (<125 mmol/L). After 7 days of 90g daily protein supplementation (n = 13), sodium levels increased by a median [IQR] of 3 mmol/L [0, 5], blood urea nitrogen increased by a median [IQR] of 4.3 mmol/L [1.7, 5.1] and urinary urea corrected for urine creatinine increased by a median [IQR] of 26.0 mmol/mmol [17.1, 32.3]. After 7 days of oral urea (n = 8), sodium levels increased by a median [IQR] of 2 mmol/L [1, 3], blood urea nitrogen increased by a median [IQR] of 8.5 mmol/L [3.8, 10.2] and urinary urea corrected for urine creatinine increased by a median [IQR] of 31 mmol/mmol [21.1, 39.8]. CONCLUSION This interim analysis suggests that high-protein supplementation with protein powder increases plasma sodium levels in patients with chronic SIAD. The increase in urea concentration in both plasma and urine upon protein supplementation is comparable to the increase upon oral urea administration, which supports protein-induced ureagenesis to be the underlying mechanism of action. Presentation: Thursday, June 15, 2023

Electrochemical determination of trace As(III) via stable rGO wrapped ammoniojarosite hydrothermally recovered from a processed liquor

The current research elucidates a simple, cost effective and highly selective platform for electrochemical detection of trace As(III) by a stable rGO wrapped ammoniojarosite. The ammoniojarosite has been recovered via pH-dependent urea-based hydrothermal pathway from a surfactant mediated acidic leach liquor of polymetallic nodules. The obtained products in the order of increasing urea concentration are ammoniojarosite (AmJ), pyrite and hematite, where the highest purity with lowest urea concentration and excellent electrochemical selectivity was showcased by AmJ. All the obtained precipitates have been characterized by SEM, EDS, XRD, RAMAN, XPS and HRTEM techniques and investigated for their electrochemical sensing application towards the presence of As(III). Since AmJ exhibited remarkable detection results and selectivity, we have synthesized a rGO@AmJ composite to amplify the detection further. As(III) was detected using cyclic voltammetry(CV), square wave anodic stripping voltammetry (SWASV) and amperometry (i-t) technique. The lower detection limit for rGO@AmJ was 0.0365 µM with ultra-high sensitivity of 114.14μAμM−1cm−2 and correlation coefficient R2 = 0.971.

The in-vitro influence of urea concentration on thromboelastrography in patients with and without end stage renal disease

BackgroundEnd stage renal disease (ESRD) is associated with platelet dysfunction but also thromboembolic complications. The specific role of increased blood urea nitrogen (BUN) on coagulation is unclear. We aimed to characterize thromboelastography (TEG) parameters from males and females with ESRD and normal kidney function and evaluate if exogenous urea in vitro reproduced those TEG differences. MethodsWe collected blood samples from 20 living kidney donors and 20 kidney recipients. TEG was performed without and with two increasing urea concentrations in vitro. TEG parameters were compared between recipients and donors. ResultsBlood from kidney recipients showed baseline increased maximum amplitude (MA) and shortened time to maximum amplitude (TMA) compared to donors. These differences were not confirmed in females. In all patients, BUN was inversely correlated with TMA (r = −0.342; p = 0.031). In males, BUN and creatinine concentrations showed a direct correlation with MA (0.583; p = 0.007) and an inverse correlation with TMA (r = −0.520; p = 0.019). Urea in vitro decreased R-time (p = 0.005) and increased LY30 (p = 0.009) in donors but not recipients. ConclusionsESRD is associated with increased MA and decreased TMA on TEG. No change in MA was observed with increasing urea concentrations in vitro. Gender-specific variability in TEG parameters were observed.

Enhancement of the thermal stability of G-quadruplex structures by urea

The solute urea has been used extensively as a denaturant in protein folding studies; double-stranded nucleic acid structures are also destabilized by urea, but comparatively less than proteins. In previous research, the solute has been shown to strongly destabilize folded G-quadruplex DNA structures. This contribution demonstrates the stabilizing effect of urea on the G-quadruplex formed by the oligodeoxyribonucleotide (ODN), G3T (d[5′-GGGTGGGTGGGTGGG-3′]), and related sequences in the presence of sodium or potassium cations. Stabilization is observed up to 7 M urea, which was the highest concentration we investigated. The folded structure of G3T has three G-tetrads and three loops that consist of single thymine residues. ODNs related to G3T, in which the thymine residues in the loop are substituted by adenosine residues, also exhibit enhanced stability in the presence of molar concentrations of urea. The circular dichroism (CD) spectra of these ODNs in the presence of urea are consistent with that of a G-quadruplex. As the urea concentration increases, the spectral intensities of the peaks and troughs change, while their positions change very little. The heat-induced transition from the folded to unfolded state, Tm, was measured by monitoring the change in the UV absorption as a function of temperature. G-quadruplex structures with loops containing single bases exhibited large increases in Tm with increasing urea concentrations. These data imply that the loop region play a significant role in the thermal stability of tetra-helical DNA structures in the presence of the solute urea.

Soil denitrification response to increased urea concentration constrains nitrous oxide emissions in a simulated cattle urine patch

Soil denitrification response to increased urea concentration constrains nitrous oxide emissions in a simulated cattle urine patch

Nitrogen forms and concentration influence the impact of titanium dioxide nanoparticles on the biomass and antioxidant enzyme activities of Microcystis aeruginosa

Nanoparticles (NPs) are becoming more widely produced, used, and released into the aquatic environment. In aquatic ecosystems, these NPs affect different populations of photosynthesizing organisms, such as cyanobacteria. This study aimed to evaluate the effects of titanium dioxide (TiO2) NPs (48mgl-1) combined with low (0.04mM) and high (9mM) concentrations of urea and nitrate on Microcystis aeruginosa. Microcystins (MCs) production and release were monitored in the cyanobacterium. The results showed that high urea concentration (9mM) combined with TiO2 NPs inhibited growth, pigment, and malondialdehyde (MDA) content by 82%, 63%, and 47%, respectively. The treatment also increased the reactive oxygen species (ROS) and glutathione S-transferase (GST) activity by 40.7% and 67.7%, respectively. Similarly, low nitrate (0.04mM) combined with TiO2 NPs inhibited growth by 40.3% and GST activity by 36.3% but stimulated pigment production and ROS concentration in M. aeruginosa. These responses suggest that high urea combined with TiO2.NPs and high nitrate combined with TiO2 NPs induced oxidative stress in cyanobacteria. The peroxidase (POD) activity of M. aeruginosa decreased by 17.7% with increasing urea concentrations. Our findings suggest that TiO2 NPs combined with changing nutrient (urea and nitrate) concentrations may adversely affect cyanobacterial development and antioxidant defense enzymes.

Effect of aqueous extract Lawsonia inermis leaves on Urea, Creatinine and Histological of kidneys in white male Rats exposed to oxidative stress of H2O2

This study was designed to examine, the effect of Effective aqueous extract Lawsonia inermis leaves as antioxidant on concentration of Urea ,Criatinine and Histological of kidneys in Albino male Rats exposed to hydrogen peroxide induced oxidative stress. This study showed that 0.5% hydrogen peroxide concentration leds to significant increase (P<0.05( in concentration of serum urea and creatinine comparing with control group. While the aqueous extract of Lawsonia inermis concentration (50mg/kg) led to significant decrease (P<0.05) in concentration of serum urea and creatinine compare with control group. Also the results showed no significant increase in concentration of urea and creatinine in group exposed to oxidative stress and aqueous extract of Henna comparing with control group. The histological results of the kidney treated with (0.5%) H2o2 showed degeneration, congestion, lymphatic infilteration, vacuolation in the renal tubules with necrosis comparing with control. While sections of kidney treated with aqueous extract of Henna showed normal appearance of the renal tubules. Histological investigation of kidneys rats treated with H2O2 and extract of Henna showed improvement in histological picture with reduction in infilteration, vacuolation and necrosis but the tissue did not return back to the normal state.

Cardiac microRNA expression profile in response to estivation

Couch's spadefoot toad (Scaphiopus couchii) spends most of the year underground in a hypometabolic state known as estivation. During this time, they overcome significant dehydration and lack of food through many mechanisms including employing metabolic rate depression (MRD), increasing urea concentration, switching to lipid oxidation as the primary energy source, and decreasing their breathing and heart rate. MicroRNA (miRNA) are known to regulate translation by targeting messenger RNA (mRNA) for degradation or temporary storage, with several studies having reported that miRNA is differentially expressed during MRD, including estivation. Thus, we hypothesized that miRNA would be involved in gene regulation during estivation in S. couchii heart. Next-generation sequencing and bioinformatic analyses were used to assess changes in miRNA expression in response to two-month estivation and to predict the downstream effects of this expression. KEGG and GO analyses indicated that ribosome and cardiac muscle contraction are among the pathways predicted to be upregulated, whereas cell signaling and fatty acid metabolism were predicted to be downregulated. Together these results suggest that miRNAs contribute to the regulation of gene expression related to cardiac muscle physiology and energy metabolism during estivation.

Alternative platform for COVID-19 diagnosis based on AuNP-modified lab-on-paper.

COVID-19 has caused global health problems, and so rapid diagnosis is crucial to slow spread of the disease. Herein, a novel lab-on-paper screening method for SARS-CoV-2 Omicron BA.2 variant was developed using a gold nanoparticle-based colorimetric biosensor along with sensitive detection of SARS-CoV-2 antigen using laser desorption ionization-mass spectrometry (LDI-MS). As a result of antigen-antibody interaction, in the presence of SARS-CoV-2 antigen the gold nanoparticles undergo aggregation and change color from red to light purple, allowing for rapid determination of SARS-CoV-2 antigen with the naked eye. Furthermore, the lab-on-paper method can be directly applied as a substrate for sensitive quantitation of SARS-CoV-2 antigen in saliva using LDI-MS without the use of a conventional organic matrix and sample preparation. LDI-MS offers early diagnosis with high sensitivity, rapidity without sample preparation and lower cost per test compared with reverse transcriptase-PCR, which is crucial for preventing mortality in patients with underlying conditions. This method showed linearity over 0.01-1 μg mL-1 covering the cut-off value of 0.048 μg mL-1 for COVID-19 detection in human saliva. Moreover, a colorimetric sensor for urea was also fabricated in-parallel, for prediction of COVID-19 severity in patients with chronic kidney disease. The color change upon increasing urea concentration directly reflected kidney damage, which is related to increasing risk of mortality among patients with COVID-19. Hence, this platform might be a potential device for non-invasive diagnosis of SARS-CoV-2 Omicron BA.2 variant, which is the variant of most concern because it is transmitted more rapidly than the original SARS-CoV-2 virus and the Delta variant.

Exploring the influence of urea on the proton-transfer reaction in aqueous amine solutions with Raman and ultrasonic relaxation spectroscopy

A combined ultrasonic and vibrational spectroscopic approach is performed, which allows measuring all the kinetic and thermodynamic parameters associated with the proton-transfer mechanisms taking place in the ternary urea- 1,1,3,3-tetramethylguanidine (TMG) -water system. The addition of urea affects extensively the already existing proton-transfer reaction that occurs when guanidine is dissolved in water. An almost perfect agreement is found between measured sound absorption dispersion and that predicted by a single Debye-type relaxation process, which can be attributed to the protonation reaction of either urea or guanidine. The experimental and theoretically predicted Raman spectra confirm the protonation of urea when added in the guanidine-water binary system. By comparing the relaxation spectra obtained for urea and amine, we observe a difference in the amplitude by several orders of magnitude, which means that since urea is the one with the higher amplitude, its protonation is the dominant contribution in the acoustic spectra of the ternary system. From the isothermal standard volume change in the ternary system with increasing urea concentration, the concentration dependence of the sound velocity, density, kinematic viscosity and classical absorption coefficient, it is evident that the addition of urea makes it difficult for the water molecules to accommodate the molecules of TMG. Urea restrains more water molecules away from the amine and breaks down the associated network of the binary system driving it to a less rigid one.

Experimental study on the calcium carbonate production rates and crystal size of EICP under multi-factor coupling

The production and microstructure of calcium carbonate are the fundamental indicators to evaluate the effectiveness of Enzyme-induced Carbonate Precipitation (EICP). Soybean urease is extracted, and the urease activity is controlled by the soybean powder concentration in this study. The urease reacts with the cementation solution with different concentrations of urea and calcium ions at different temperatures to determine the calcium carbonate production rates (RCC). The crystal sizes of calcium carbonate (SCC) are investigated by scanning electron microscopy (SEM) and image processing method. The RCC increase and subsequently decrease with increasing calcium ion concentration and peak at 0.75 M. A lower urea concentration is more favourable to the formation of CaCO3. Increased urease activity and temperature will lead to an increased RCC and SCC. Some crystals appear as capsules when the temperature goes up. The SCC decreases slightly with increasing calcium ion concentration under low urease activity and increases under high urease activity. The SCC increases first and subsequently decreases with increasing urea concentration under high urease activity, while the effect of urea concentration under low urease activity is not significant. XRD test results show that the calcium carbonate produced in this study is dominated by calcite crystals. The study provides additional data, a useful base to move forward toward a better understanding of the method of stabilization and its applications, for example, the treatment of different soils.

Facile synthesis of N-doped biphasic TiO2 nanoparticles with enhanced visible light-driven photocatalytic performance

Undoped and N-doped TiO2 anatase/brookite mixed-phase nanoparticles were synthesized via a facile sol-gel method using urea as a nitrogen source. Surprisingly, nitrogen played a dual role in doping and controlling the anatase and brookite phases in the nanoparticles. The as-synthesized photocatalysts were characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis and UV–vis diffuse reflectance spectroscopy (DRS). PXRD results revealed that TiO2 nanoparticles consisted of a mixture of anatase and brookite crystalline phases where the anatase phase increased with increasing urea concentration (1–60 wt. %), and the pure anatase phase was found at a urea concentration of ≥15 wt. %. N-doped anatase/brookite mixed-phase (brookite ̴ 20 wt. %) nanoparticles exhibited superior photocatalytic activity over others in degrading rhodamine-B (RhB) under simulated visible light irradiation, and its photocatalytic performance was comparable to that of Degussa P25. The enhanced photodegradation activity was credited to biphasic composition, narrower bandgap energy, and stronger light absorption in the visible region.

Removal Behavior of Heavy Metals from Aqueous Solutions via Microbially Induced Carbonate Precipitation Driven by Acclimatized Sporosarcina pasteurii

Microbially induced carbonate precipitation (MICP) driven by Sporosarcina pasteurii was highly efficient for heavy metal (i.e., Cd2+, Cu2+ and Pb2+) removal in the range of 50 to 800 mg/L. Sporosarcina pasteurii bacteria were sequentially inoculated in nutrient broths amended with increased concentrations of heavy metals separately to improve the resistance to heavy metal environments. In the absence of Ca2+, the increasing urea concentration was conducive to Cd2+ removal with the best removal ratio 89.9–99.7% at a urea concentration of 2.0 mol/L, but had little positive effect on Cu2+ and Pb2+ removal, with a removal ratio of 62.6–64.4% and 71.4–97.6%, respectively, at a urea concentration of 0.5 mol/L. The heavy metal coprecipitated with Ca2+, leading to much more effective heavy metal removal, and the removal efficiency of Cd2+, Cu2+ and Pb2+ could reach 98.0–99.0, 78.1–82.1 and 98.0–100.0%, respectively. The Cu2+ deposit aggregated and cemented to form clusters, different from Cd2+ and Pb2+ deposits with comparatively dispersed microstructure. For all the three heavy metal precipitates, the predominant mineral was identified as calcite, the most thermodynamically stable polymorph of CaCO3.