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1.
Water Sci Technol ; 83(4): 803-817, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33617488

RESUMO

In the previous study, greenhouse gas CO2 was successfully used as the precipitator to realize its carbonation by calcium ions in seawater with the help of magnesium oxide. In this study, the reaction process was firstly analyzed by a proposed reaction mechanism, and then the dynamic simulation of the gas-liquid-solid system was carried out via kinetic Monte Carlo simulation. Based on the reaction mechanism, the continuous experimental study was realized in a bubble column. The effects of air flow rate, carbon dioxide flow rate and temperature on the effectiveness evaluation indexes of decalcification efficiency, total mass transfer coefficient and carbon sequestration rate were studied. Finally, a bonnet tower with a diameter of 1 m and a height of 8 m was built to carry out the pilot test. In the laboratory experiments, the calcium removal rate reached 94%, the carbon sequestration rate reached 63.6%, and pure micron calcium carbonate products were obtained. The decalcification rate reached 95% in the pilot test, which is consistent with the results of the laboratory experiment.


Assuntos
Dióxido de Carbono , Sequestro de Carbono , Carbonato de Cálcio , Carbonatos , Água do Mar
2.
Ecotoxicol Environ Saf ; 208: 111548, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396092

RESUMO

In order to understand the pollution status of groundwater with geochemical evolution and appraisal of its probable public health risk due to nitrate (NO3-) and fluoride (F-), a total of 93 groundwater samples were collected during pre-monsoon (May) period from Wardha sub-basin, central India. By employing Piper plot, transition from Ca-HCO3 type water (recharge waters) to Na-Cl (saline water) type water through mixed Ca-Na-HCO3, mixed Ca-Mg-Cl (reverse ion exchange waters) and Ca-Cl types (leachate waters), were observed. The Geogenic processes such as silicate, dolomite, halite and carbonate weathering along with calcite precipitation and ion exchange process were identified as major controlling factors for evolution and alteration of groundwater chemistry. The Saturation index highlighted that the groundwater in the area is oversaturated with respect to the mineral calcite and dolomite, and under saturated with gypsum, fluorite and halite. The high NO3- and F- concentration overpassing the permissible limit were found in 54.8% and 18.5% of samples. The plot of F- with Na+/Ca2+, Na+/Mg2+ and F-/Cl- established fluoride bearing rock weathering is responsible for F- contamination. Based on the cluster analysis, the groundwater was grouped into Cluster-I Ca-Na-HCO3 type (61.3%) and Cluster-II Na-Ca-HCO3-Cl type (30.1%). The total hazard index (HI) based on human health risk assessment (HHRA) model for cumulative NO3- and F- toxicity through oral and dermal pathways were computed as 100%, 97.85% and 96.77% for children, female and male populations respectively. The HQ(nitrate) > 1 through ingestion pathway were in 84.95%, 68.82% and 62.37%, and HQ(fluoride) > 1 in 83.87%, 62.37% and 43.01% of the groundwater samples were recorded for children, female and male population respectively. The risk assessment study highlighted very high toxicity and severe health impact of ingestion of contaminated groundwater on public health.


Assuntos
Monitoramento Ambiental , Fluoretos/toxicidade , Nitratos/toxicidade , Poluentes Químicos da Água/toxicidade , Carbonato de Cálcio , Carbonatos , Criança , Feminino , Fluoretos/análise , Água Subterrânea/análise , Água Subterrânea/química , Humanos , Índia , Troca Iônica , Magnésio , Nitratos/análise , Medição de Risco , Poluentes Químicos da Água/análise
3.
BMJ Case Rep ; 14(1)2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33408101

RESUMO

Highly active antiretroviral therapy (HAART) has dramatically lowered rates of mother-to-child HIV transmission among patients with access to treatment. Barriers to complete viral suppression increase rates of transmission, even with only low levels of viral replication. Here, we present the case of a pregnant patient who developed a detectable viral load in pregnancy, thought to be related to calcium supplement consumption or emesis while using a dolutegravir-based HAART regimen. Ultimately, with adjustments, the patient again reached an undetectable viral load and had an uncomplicated perinatal and neonatal outcome. We discuss new data on the use of dolutegravir in pregnancy and precautions for maintaining viral suppression while on antiretroviral therapy in pregnancy.


Assuntos
Fármacos Anti-HIV/farmacologia , Terapia Antirretroviral de Alta Atividade/métodos , Infecções por HIV/tratamento farmacológico , Medicamentos sem Prescrição/farmacologia , Complicações Infecciosas na Gravidez/tratamento farmacológico , Adulto , Fármacos Anti-HIV/uso terapêutico , Contagem de Linfócito CD4 , Carbonato de Cálcio/farmacologia , Interações Medicamentosas , Feminino , Infecções por HIV/sangue , Infecções por HIV/transmissão , Infecções por HIV/virologia , HIV-1/isolamento & purificação , Humanos , Transmissão Vertical de Doença Infecciosa/prevenção & controle , Gravidez , Complicações Infecciosas na Gravidez/virologia , Carga Viral/efeitos dos fármacos , Vitaminas/farmacologia , Vômito/induzido quimicamente
4.
J Environ Sci (China) ; 99: 210-221, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183699

RESUMO

Assisted natural remediation (ANR) has been highlighted as a promising, less expensive, and environmentally friendly solution to remediate soil contaminated with heavy metals. We tested the effects of three amendments (10% compost, C; 5 or 15% phosphate sludge, PS5 and PS15; and 5 or 15% marble waste, MW5 and MW15) in combination with microorganism inoculation (rhizobacteria consortium alone, mycorrhizae alone, and the two in-combination) on alfalfa in contaminated soil. Plant concentrations of Zn, Cu, and Pb were measured, along with proline and malondialdehyde production. The microbiological and physicochemical properties of the mining soil were evaluated. Application of the amendments allowed germination and promoted growth. Inoculation with the rhizobacteria consortium and/or mycorrhizae stimulated plant growth. PS and MW stimulated the production of proline. Inoculation of alfalfa with the rhizobacteria-mycorrhizae mixture and the application of MW allowed the safe cultivation of the legume, as shown by the low concentrations of metals in plant shoots. Zn and Pb concentrations were below the limits recommended for animal grazing and accumulated essentially in roots. Soil analyses showed the positive effect of the amendments on the soil physicochemical properties. All treatments increased soil pH (around 7), total organic carbon, and assimilable phosphorus content. Notably, an important decrease in soluble heavy metals concentrations was observed. Overall, our findings revealed that the applied treatments reduced the risk of metal-polluted soils limiting plant growth. The ANR has great potential for success in the restoration of polymetallic and acidic mining soils using the interaction between alfalfa, microorganisms, and organo-mineral amendments.


Assuntos
Metais Pesados , Poluentes do Solo , Animais , Carbonato de Cálcio , Metais Pesados/análise , Fosfatos , Esgotos , Solo , Poluentes do Solo/análise
5.
Sci Total Environ ; 753: 141902, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33207459

RESUMO

One of negative side-effects of usage of bio-renewables might be generation of mineral (ash) material, potential source of environmental pollution. A hypothesis was that bottom ash (BA; from biomass cogeneration facility) could be efficiently (re) used in soil chemical conditioning similarly to widely-used dolomite-based soil conditioner (DO; from Croatian Dinaric-coastal region) which we tested by: i) physicochemical characterisation of BA and DO, and ii) bioassay with Raphanus sativus cultivated in acidic soil amended with BA or DO. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) confirmed complex chemical/physical structures and morphology between amendments, X-ray diffraction (XRD) showed their distinctive mineralogy with predominantly dolomite (in DO) vs. quartz and calcite (in BA), while secondary ion mass spectrometry (SIMS) revealed their diverse elemental/isotopic composition. The BA or DO amendments ameliorated soil acidity, increased available P, K and most other nutrients, but not Cd. The BA or DO amendments improved vegetative growth and edible hypocotyl yield. However, both amendments also increased Cd accumulation in all radish tissues, which was unexpected given the alkaline matrix of bio-ash and dolomite that would be likely to facilitate retention and immobilisation of toxic Cd. Thus, thorough characterisation and evaluation of BA- and/or DO-based materials and relevant soils (with an emphasis on metal sorption/immobilisation) prior to application in (agro) ecosystems is crucial for producing food clean of toxic metals.


Assuntos
Raphanus , Poluentes do Solo , Biomassa , Cádmio/análise , Carbonato de Cálcio , Cinza de Carvão , Ecossistema , Magnésio , Nutrientes , Solo , Poluentes do Solo/análise
6.
Food Chem ; 338: 127842, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32822902

RESUMO

Cadmium, inorganic arsenic and, potentially, dimethyl arsenic acid are carcinogens widely elevated in rice. Here it was identified that the food-safe and common cadmium chelator citric acid efficiently removed cadmium from intact grain via pre-soaking procedure, while also reducing arsenic species. A twostep pre-soaking stage was developed whereby rice was first incubated, at ambient temperature, in 1 M citric acid for 12 h, and then in 1 M calcium carbonate for another 12 h, the latter step to neutralize pH, followed by cooking. When 10 different individual types of rice were processed in such a way this resulted in removal rates of 79% for cadmium, 81% for inorganic arsenic and a 66% for DMA. The technology is particularly suitable for bulk food processing and could be deployed in the most cadmium and arsenic impacted regions where rice is a staple.


Assuntos
Arsenicais/química , Ácido Cacodílico/química , Cádmio/química , Contaminação de Alimentos/análise , Oryza/química , Arsenicais/análise , Ácido Cacodílico/análise , Cádmio/análise , Carbonato de Cálcio/química , Ácido Cítrico/química , Culinária/métodos , Concentração de Íons de Hidrogênio , Espectrometria de Massas/métodos , Oryza/metabolismo
7.
Chemosphere ; 263: 127920, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32822936

RESUMO

Arsenic (As) and selenium (Se) pollution caused by coal combustion is receiving increasing concerns. The environmental impacts of As/Se are determined not only by stack emission but also by leaching process from combustion byproducts. For a better control of As/Se emission from As/Se-enriched coal combustion, this study investigated the migration and emission behavior of As/Se in a circulating fluidized bed (CFB) power plant equipped with fabric filter (FF) and wet flue gas desulfurization (WFGD) system. The results demonstrated that arsenic was both enriched in bottom ash (41.4-47.6%) and fly ash (52.4-58.6%), while selenium was mainly captured by fly ash (73.9-83.4%). Limestone injection into furnace promoted As/Se retention in ash residues. Arsenic was mainly converted into arsenate in high-temperature regions and partly trapped in bottom ash as arsenite. In contrast, selenium capture mainly occurred in low-temperature flue gas by the formation of selenite, because of the poor thermal stability of most selenite. Triplet-tank method can totally remove arsenic in WFGD wastewater. And 18.4-58.7% of selenium was removed, resulting from the precipitation of Se4+ anions with highly soluble Se6+ anions remaining in wastewater. The concentrations of As and Se in the stack emission were 0.25-1.02 and 0.96-2.24 µg/m3, receptively. The CFB boiler equipped with FF + WFGD was shown to provide good control of the As/Se emission into the atmosphere. Leaching tests suggested that more attention should be paid to As leachability from fly ash/gypsum, and Se leachability from gypsum/sludge.


Assuntos
Poluentes Atmosféricos/análise , Arsênico/análise , Centrais Elétricas , Selênio/análise , Atmosfera , Leitos , Carbonato de Cálcio , Sulfato de Cálcio , Carvão Mineral/análise , Cinza de Carvão/química , Monitoramento Ambiental , Gases
8.
Chemosphere ; 266: 129202, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33310517

RESUMO

Sandy soils in Florida are vulnerable to toxic metal pollution, and it is necessary to identify desirable amendments for the remediation of metal contaminated soils. Sorption and incubation experiments were conducted to compare the effectiveness of dolomite phosphate rock (DPR), humic acid activated dolomite phosphate rock (ADPR) and biochar (BC) in immobilizing Cd2+ and Pb2+ in two representative agricultural soils in south Florida (Alfisol-Riviera and Spodosol -Ankona series). The results showed that the soils had a low sorption capacity for metals with maximum sorption of 0.767-3.30 mg/g. Application of amendments increased the maximum sorption by 4.2-4.8 times for Pb2+ and 1.5-2.2 times for Cd2+ in Alfisol soil, and 7.1-7.9 times for Pb2+ and 1.7-3.1 times for Cd2+ in Spodosol soil. ADPR was the most effective amendment for increasing the soil's sorption capacity for Cd2+ and Pb2+. 0.01 M CaCl2 extractable metals in the contaminated soils were significantly decreased by all the amendments, especially ADPR, which reduced extractable Cd2+ and Pb2+by 87.2 and 76.0% in Alfisol and 91.3 and 76.3% in Spodosol soil as compared to control. The amounts of extractable Cd2+ and Pb2+ were negatively correlated with soil pH and available P, indicating that the change of soil characteristics by amendments was the dominant mechanism for enhanced immobilization of metals in the contaminated soils. These results indicate that ADPR has great potential for remediating toxic levels of Cd2+ and Pb2+ in contaminated soils.


Assuntos
Metais Pesados , Poluentes do Solo , Cádmio/análise , Carbonato de Cálcio , Carvão Vegetal , Florida , Chumbo , Magnésio , Metais Pesados/análise , Fosfatos , Solo , Poluentes do Solo/análise
9.
Ecotoxicol Environ Saf ; 207: 111512, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33254392

RESUMO

This study investigated 324 groundwater samples collected from the southwest plain of Shandong Province during the dry and wet seasons. Groundwater fluoride in the study area and the influencing factors were characterized and discussed using statistical analysis, ion ratios, Piper diagrams, the saturation index (SI) and ArcGIS software. In addition, the risk posed by groundwater fluoride to human health was assessed. The results showed that groundwater in the study area had elevated fluoride concentrations, with average dry and wet season concentrations of 1.15 mg·L-1 and 1.08 mg·L-1, respectively. Groundwater fluoride showed consistent spatial variations during the dry and wet seasons, with a significant regionalization pattern of low concentrations in the east and high concentrations in the west. Groundwater F- was significantly negatively correlated with Ca2+ and positively correlated with pH, HCO3- and Na+. Important factors identified as having an effect on groundwater F- in the study area included the balance of dissolution of fluorite and calcite, the weakly alkaline environment and cation exchange. In addition, hydrochemical types of high-fluoride groundwater in the study area were identified as mainly HCO3-Na and SO4·Cl-Na. The assessment of the risk of high groundwater fluoride to human health showed that children are more at risk compared to adults, with the risk during the dry season exceeding that over the wet season. It is recommended that water quality management in the study area prioritize the formulation of measures to mitigate high concentrations of fluoride in groundwater .


Assuntos
Monitoramento Ambiental , Fluoretos/análise , Poluentes Químicos da Água/análise , Adulto , Carbonato de Cálcio/química , Criança , China , Água Subterrânea/química , Saúde , Humanos , Minerais/análise , Sódio/análise , Qualidade da Água
10.
Ecotoxicol Environ Saf ; 209: 111773, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33340953

RESUMO

Cadmium (Cd) is a highly toxic heavy metal that occurs widely in the environment and poses extensive threats to human health, animals, and plants. This study aims to identify and apportion multi-source and multi-phase Cd pollution from natural and anthropogenic inputs using ensemble models that include random forest (RF) in agricultural soils on Karst areas. The contributions of natural and anthropogenic factors to Cd accumulation were quantitatively assessed using the RF machine learning method. The results revealed that the main influencing factors were pH, organic carbon (Corg), and elevation. Moreover, the interaction effects of pH and Corg on distance and elevation were also quantified and visualised. It is observed that pH and Corg had stronger effects on soil Cd concentration than that of distance when pH > 7.02 and Corg > 1.53. In other words, higher Cd content in the soil along roadways may be caused by the interaction of distance, pH and Corg, with pH and Corg playing the dominant role in our case. Moreover, the maximum contribution of a single factor, elevation, to Cd concentration was about 0.13 mg/kg, and its interactions reached 1.082 mg/kg and 0.83 mg/kg, respectively, when combined with pH and Corg at 194.0 m. However, with increasing elevation, pH and Corg gradually took over the leading roles. This result not only gives us a quantitative understanding of the relationship between the factors that affect soil cadmium accumulation, but also provides an accurate method for source apportionment of heavy metals in soil.


Assuntos
Cádmio/análise , Monitoramento Ambiental/métodos , Poluição Ambiental/estatística & dados numéricos , Poluentes do Solo/análise , Agricultura , Carbonato de Cálcio , China , Poluição Ambiental/análise , Humanos , Metais Pesados/análise , Solo/química
11.
Ecotoxicol Environ Saf ; 209: 111785, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33348254

RESUMO

Heavy metals are considered contaminants that hazardously influence the healthy life of humans and animals as they are widely used in industry. Contact of youngsters and women at ages of parturition with lead (Pb+2) is a main related concern, which passes through the placental barricade and its better absorption in the intestine leads to flaws in the fetal developfment. However, the metals threaten animal and human life, in particular throughout developmental stages. Products existing in the nature have a major contribution to innovating chemo-preventives. As a naturally available polyphenol and necessary curcuminoid, curcumin (Cur) is a derivative of the herb Curcuma longa (L.) rhizome, which globally recognized as "wonder drug of life"; however, Cur has a limited clinical use as it is poorly dissolved in water. Therefore, to enhance its clinically relevant parameters, curcumin-loaded calcium carbonate (CaCO3@Cur) was synthesized by one step coprecipitation method as a newly introduced in this research. Initially, its structure was physio chemically characterized using FT-IR, FESEM and DLS equipment and then the cytotoxicity of lead when it was pretreated with Cur/CaCO3@Cur were assessed by MTT assay. Both Cur and CaCO3@Cur diminished the toxic effects of Pb+2 while the most protective effect on the Pb+2 cytotoxicity was achieved by pre-incubation of cells with CaCO3@Cur. Besides, the morphological changes of Pb+2-treated cells that were pre-incubated with or without Cur/CaCO3@Cur were observed by normal and florescent microscopes. A non-pharmacologic method that lowers the hazard of brain damage is exercise training that is capable of both improving and alleviating memory. In the current study, the role of regular aerobic training and CaCO3@Cur was assessed in reducing the risk of brain damage induced by lead nitrate contact. To achieve the mentioned goal, pregnant Balb/C mice were assigned to five groups (six mice/group) at random: negative and positive controls, aerobic training group and Cur and CaCO3@Cur treated (50 mg/kg/b.wt) trained groups that exposed to Pb+2 (2 mg/kg) by drinking water during breeding and pregnancy. With the completion of study, offspring were subjected to the behavioral tasks that was tested by step-through ORT, DLB, MWM and YM tests. As a result, having regular aerobic training and CaCO3@Cur co-administration with lead nitrate could reverse the most defected behavioral indicators; yet, this was not visible for both sexes and it seems that gender can also be a source of different effects in the animal's body. In fact, having regular aerobic training along with CaCO3@Cur supplementation during pregnancy may be encouraging protecting potential agents towards the toxicity of Pb+2 that could be recommended in the areas with high pollution of heavy metals.


Assuntos
Carbonato de Cálcio , Disfunção Cognitiva/prevenção & controle , Curcumina , Suplementos Nutricionais , Substâncias Perigosas/toxicidade , Chumbo/toxicidade , Animais , Curcuma/efeitos dos fármacos , Feminino , Humanos , Masculino , Camundongos , Nitratos , Extratos Vegetais , Gravidez , Espectroscopia de Infravermelho com Transformada de Fourier
12.
Ecotoxicol Environ Saf ; 209: 111840, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33383343

RESUMO

Heavy-metal contamination is widespread in agricultural soils worldwide, especially paddy soils contaminated by Cd. Amendment-induced immobilization of heavy metals is an attractive and effective technique, provided that cost-effective materials are used. This field experiment compared three alkaline passivators (attapulgite, processed oyster shell powder, and mixed soil conditioner) at a rate of 2.25 t ha-1 for their effectiveness in decreasing Cd bioavailability in soils and accumulation in rice plants in a paddy field contaminated by Cd (0.38 Cd mg kg-1). The utilization of attapulgite and processed oyster shell powder decreased labile fractions but increased stable fractions of Cd in soils through ion exchange, precipitation and complexation. The addition of attapulgite decreased the concentration of bioavailable Cd in both bulk and rhizosphere soils, whereas the amendment of processed oyster shell powder decreased it only in bulk soil. The Cd accumulation in rice plants correlated significantly with acid-soluble and residual Cd fractions in the rhizosphere soil but not in the bulk soil. The addition of attapulgite and processed oyster shell powder decreased Cd accumulation in rice grains from 0.26 mg kg-1 to 0.14 and 0.19 mg kg-1, respectively, meeting the National Food Safety Standard (< 0.20 mg kg-1). However, the mixed soil conditioner did not decrease the Cd accumulation in rice shoots or grains. This study demonstrated that attapulgite and processed oyster shell powder were economic agents in reducing Cd accumulation in rice grains.


Assuntos
Cádmio/metabolismo , Recuperação e Remediação Ambiental/métodos , Compostos de Magnésio , Oryza/metabolismo , Compostos de Silício , Poluentes do Solo/metabolismo , Ácidos , Agricultura , Exoesqueleto/química , Animais , Disponibilidade Biológica , Cádmio/análise , Carbonato de Cálcio , Ostreidae , Pós , Rizosfera , Solo , Poluentes do Solo/análise
13.
Water Res ; 190: 116753, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33360619

RESUMO

Reusing produced water (PW) as the subsequent hydraulic fracturing fluid is currently the most economical and dominant practice in the shale oil and gas industry. However, high Ca2+ present in PW needs to be removed prior to reuse to minimize the potential for well clogging and formation damage. In this study, the microbially induced calcite precipitation (MICP), as an emerging biomineralization technique mediated by ureolytic bacteria, was employed to remove Ca2+ and toxic contaminants from hypersaline PW for the first time. Batch and continuous studies demonstrated the feasibility of MICP for Ca2+ removal from hypersaline PW under low urea and nutrient conditions. Throughout the continuous biofiltration operation with biochar as the media, high removal efficiencies of Ca2+ (~96%), organic contaminants (~100%), and heavy metals (~100% for As, Cd, Mn and Ni, 92.2% for Ba, 94.2% for Sr) were achieved when PW co-treated with synthetic domestic wastewater (SDW) under the condition of PW:SDW = 1:1 & urea 4 g/L. Metagenomic sequencing analysis showed that a stable ureolytic bacterial consortium (containing Sporosarcina and Arthrobacter at the genus level) was constructed in the continuous biofiltration system under hypersaline conditions, which may play a crucial role during the biomineralization process. Moreover, the combination of the MICP and ammonium recovery could significantly reduce the acute toxicity of PW towards Vibrio fischeri by 72%. This research provides a novel insight into the biomineralization of Ca2+ and heavy metals from hypersaline PW through the MICP technique. Considering the low cost and excellent treatment performance, the proposed process has the potential to be used for both hydraulic fracturing reuse and desalination pretreatment on a large scale.


Assuntos
Carbonato de Cálcio , Sporosarcina , Biomineralização , Precipitação Química , Ureia , Água
14.
Chemosphere ; 262: 128357, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182098

RESUMO

The cost-effective recovery of phosphate is of great significance to the mitigation of phosphorus resource depletion crisis. The electrochemical-decomposition of dolomite was developed to recover phosphate and ammonium from aqueous solution. The dolomite ore is mainly composed of CaMg(CO3)2 (53.73%), CaCO3 (28.93%) and SiO2 (16.59%). The continuous release of Mg2+ and Ca2+ were achieved by electrochemically decomposing dolomite ore, accompanied by the generation of base solution (9.0-10.5). The main factors affecting the recovery performance of phosphate (PO4-P) and ammonium (NH4-N) are current, initial concentration of PO4-P and NH4-N, initial pH of feed solution and feed rate. For a 30-d operation, the recovery rate of PO4-P was maintained at 90-97% and that of NH4-N at 50-60% under optimized operating conditions. The recovered product had low water solubility but high citric-acid-soluble, and was proposed as a slow-release fertilizer for crops. The proposed process as a simple, effective and green route may serve as a new strategy for recovering PO4-P and NH4-N from wastewaters.


Assuntos
Compostos de Amônio/química , Carbonato de Cálcio/química , Técnicas Eletroquímicas/métodos , Magnésio/química , Fosfatos/química , Eliminação de Resíduos Líquidos/métodos , Compostos de Amônio/isolamento & purificação , Cálcio/química , Eletrodos , Fertilizantes , Concentração de Íons de Hidrogênio , Fosfatos/isolamento & purificação , Fósforo/química , Dióxido de Silício , Soluções , Águas Residuárias/química , Poluentes Químicos da Água/química
15.
Nat Commun ; 11(1): 5678, 2020 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-33173053

RESUMO

While many organisms synthesize robust skeletal composites consisting of spatially discrete organic and mineral (ceramic) phases, the intrinsic mechanical properties of the mineral phases are poorly understood. Using the shell of the marine bivalve Atrina rigida as a model system, and through a combination of multiscale structural and mechanical characterization in conjunction with theoretical and computational modeling, we uncover the underlying mechanical roles of a ubiquitous structural motif in biogenic calcite, their nanoscopic intracrystalline defects. These nanoscopic defects not only suppress the soft yielding of pure calcite through the classical precipitation strengthening mechanism, but also enhance energy dissipation through controlled nano- and micro-fracture, where the defects' size, geometry, orientation, and distribution facilitate and guide crack initialization and propagation. These nano- and micro-scale cracks are further confined by larger scale intercrystalline organic interfaces, enabling further improved damage tolerance.


Assuntos
Biomineralização , Bivalves/metabolismo , Carbonato de Cálcio/metabolismo , Cerâmica/química , Animais , Simulação por Computador , Modelos Biológicos
16.
J Contemp Dent Pract ; 21(6): 609-614, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33025927

RESUMO

AIM: This clinical study aimed to evaluate the efficacy of a toothpaste containing a proprietary REFIX technology (Regenerador + Sensitive DentalClean, Rabbit Corp) against dentin hypersensitivity. MATERIALS AND METHODS: Fifty-three volunteers who fulfilled the inclusion criteria and signed the consent form were included. They were examined for dentin hypersensitivity. The participants received a 1-second blast of air, and the tooth sensitivity, from 0 to 10, was immediately evaluated using a visual analog scale (VAS). Then, the participants brushed their teeth with the multifunctional toothpaste, and dentin hypersensitivity was tested a second time using the same scale. The participants continued to use the toothpaste three times a day for 1 week, after which dentin hypersensitivity was recorded for the third time. Data were statistically analyzed using analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS: The mean patient age was 40 years, and 70% of the 53 subjects were female. There was a significant reduction in dentin hypersensitivity immediately after using the toothpaste and after 1 week. The baseline mean patient-reported pain score was severe (6.5 ± 2.4). Immediately after the first use of the toothpaste, the mean reported pain significantly decreased to mild pain (2.5 ± 2.5) (p < 0.05). After 1 week of consistent use of the toothpaste, the pain score reduced significantly (0.7 ± 1.2) (p < 0.05), and most participants reported no pain, demonstrating the effectiveness of the REFIX technology against dentin hypersensitivity. CONCLUSION: This clinical trial shows that the use of the phosphate-based desensitizing toothpaste containing REFIX technology significantly reduces dentin hypersensitivity after 1 week of consistent use. CLINICAL SIGNIFICANCE: The absence of pain, a desired clinical condition in patients with dentin hypersensitivity, was reached with the use of desensitizing toothpaste containing REFIX technology after 1 week of use. Such condition positively impacts quality of life, providing a healthier daily routine for patients.


Assuntos
Dessensibilizantes Dentinários , Sensibilidade da Dentina , Cremes Dentais , Arginina , Carbonato de Cálcio , Dessensibilizantes Dentinários/uso terapêutico , Sensibilidade da Dentina/tratamento farmacológico , Sensibilidade da Dentina/prevenção & controle , Método Duplo-Cego , Feminino , Fluoretos , Humanos , Qualidade de Vida , Fluoreto de Sódio , Escovação Dentária , Cremes Dentais/uso terapêutico , Resultado do Tratamento
17.
Zootaxa ; 4766(3): zootaxa.4766.3.4, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33056591

RESUMO

A new genus and new species of terrestrial freshwater crab, Calcipotamon puglabrum gen. nov. et sp. nov., is described from the limestone forests of Changjiang, Hainan Island, China, based on morphology and mitochondrial 16S rDNA sequences. The new genus is closest to Neotiwaripotamon Dai Naiyanetr, 1994, and Tiwaripotamon Bott, 1970, but differs in a combination of carapace, third maxilliped, ambulatory leg and male gonopod characters. Molecular analysis shows that the new genus is closely related with but not clustered within other Hainan potamid genera. Notes on the general biology of this new species are also provided.


Assuntos
Braquiúros , Animais , Carbonato de Cálcio , China , Água Doce , Ilhas , Masculino
18.
Zootaxa ; 4808(2): zootaxa.4808.2.2, 2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-33055975

RESUMO

In this paper, we describe three new Eukoenenia species from specimens collected in limestone caves in the northern region of the Minas Gerais state, Brazil. These species present different degrees of adaptation to the subterranean habitat, with Eukoenenia magna sp. nov., with 6 blades on lateral organs and body ratios very close to other troglobitic species, being the most troglomorphic among them. This species is morphologically very similar to the Brazilian troglobites E. navi, E. eywa and E. neytiri. Eukoenenia lundi sp. nov. and Eukoenenia jequitai sp. nov. are probably closely related species due to their substantial morphological resemblance. These two species are closer to E. virgemdalapa among the Brazilian species described to date. We provide a table summarizing the main diagnostic characters of the three species herein described and those of the Brazilian congeners to facilitate morphological comparisons.


Assuntos
Aracnídeos , Adaptação Fisiológica , Animais , Brasil , Carbonato de Cálcio , Ecossistema
19.
Water Res ; 186: 116334, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32866932

RESUMO

Cooling circuits in many industrial sectors are faced with daily issues of scaling. One preventive treatment consists in injecting a polymer additive in the circuit to inhibit precipitation of calcium carbonate. Among the used additives, very few are "green" and the efficiency of new candidates are difficult to test directly in industrial conditions. The present study compared performance between two "green" polymer additives, polyaspartic acid (PASP) and polyepoxysuccinic acid (PESA), versus a traditional gold-standard, homopolymer of acrylic acid (HA) in a laboratory scale set-up designed to be representative of an industrial circuit. Results showed that HA and PASP are both inhibitors of calcium carbonate crystal growth. This inhibition resulted from adsorption of polymer additive molecules on the crystal surface, as confirmed by adsorption measurement. Under the same conditions, PESA additive, showed a high rate of calcium ion complexation and a very low inhibition rate. But, PESA was shown to be a nucleation delayer. Mixing PESA and PASP can gave nucleation retardation of about 19 h, which approximates the 24 h water residence time in industrial cooling circuits, as well as almost 90% calcium carbonate crystal growth inhibition. This synergy offers promising prospects for preventive scaling treatment.


Assuntos
Carbonato de Cálcio , Polímeros , Precipitação Química , Íons
20.
Proc Biol Sci ; 287(1934): 20201506, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32900308

RESUMO

The sea urchin embryo develops a calcitic endoskeleton through intracellular formation of amorphous calcium carbonate (ACC). Intracellular precipitation of ACC, requires [Formula: see text] concentrating as well as proton export mechanisms to promote calcification. These processes are of fundamental importance in biological mineralization, but remain largely unexplored. Here, we demonstrate that the calcifying primary mesenchyme cells (PMCs) use Na+/H+-exchange (NHE) mechanisms to control cellular pH homeostasis during maintenance of the skeleton. During skeleton re-calcification, pHi of PMCs is increased accompanied by substantial elevation in intracellular [Formula: see text] mediated by the [Formula: see text] cotransporter Sp_Slc4a10. However, PMCs lower their pHi regulatory capacities associated with a reduction in NHE activity. Live-cell imaging using green fluorescent protein reporter constructs in combination with intravesicular pH measurements demonstrated alkaline and acidic populations of vesicles in PMCs and extensive trafficking of large V-type H+-ATPase (VHA)-rich acidic vesicles in blastocoelar filopodial cells. Pharmacological and gene expression analyses underline a central role of the VHA isoforms Sp_ATP6V0a1, Sp_ATP6V01_1 and Sp_ATPa1-4 for the process of skeleton re-calcification. These results highlight novel pH regulatory strategies in calcifying cells of a marine species with important implications for our understanding of the mineralization process in times of rapid changes in oceanic pH.


Assuntos
Bicarbonatos/metabolismo , Ouriços-do-Mar/fisiologia , Animais , Transporte Biológico , Calcificação Fisiológica , Carbonato de Cálcio , Concentração de Íons de Hidrogênio , Oceanos e Mares , Prótons , Água do Mar
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