Angelica Naka - Academia.edu (original) (raw)
Papers by Angelica Naka
Applied biosciences, May 8, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Salud, Ciencia y Tecnología, May 17, 2024
Geosynthetics engineering journal, 2012
Geosynthetics engineering journal, 2010
The capacity of geosynthetic clay liners (GCLs) to attenuate metals and metalloids such as Al, Fe... more The capacity of geosynthetic clay liners (GCLs) to attenuate metals and metalloids such as Al, Fe, Cu, Zn, As, and Pb was evaluated in this study. For this purpose, free swell, sorption, and hydraulic conductivity tests on a needlepunched geosynthetic clay liner against a pH 3 artificial acid rock drainage (ARD) were conducted. Free swelling tests showed that at high metal concentration, the swell index decreased dramatically. Sorption test results showed that Na-bentonite had high capacity to sorb metals and metalloids. Hydraulic conductivity tests showed that k was 10 times lower when GCL was prehydrated with water, before permeating with ARD. Effluents were also evaluated in each case and results showed that the GCL tested has strong attenuation capacity toward metals and metalloids present in ARD, although desorption was observed in some cases.
Applied Biosciences, Jan 10, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Soils and Foundations, Oct 1, 2019
The hydraulic and chemical compatibility of a geosynthetic clay liner (GCL), containing powdered ... more The hydraulic and chemical compatibility of a geosynthetic clay liner (GCL), containing powdered Na-bentonite, was evaluated against artificial acid rock drainage (ARD) in terms of the swell index, hydraulic conductivity and heavy metal retention. Six artificial ARDs with an approximate pH of 3 and different metal concentrations (electrical conductivity, EC, ranging between 75 and 1000 mS/m; ionic strength ranging between 8 and 400 mM) were used in the experiments. The results of free swelling tests showed that high metal concentrations (EC higher than 70 mS/m) negatively impact the swell volume by lowering it. The hydraulic conductivity of the GCL permeated with distilled water was 1.2 Â 10 À11 m/s, falling in the range of 7.9 Â 10 À12 to 1.1 Â 10 À10 m/s when prehydrated with distilled water and permeated with ARDs. The ion exchange and metal precipitation appeared to be the main mechanisms controlling the metal attenuation on the bentonite. The ion exchange mechanism starts with the release of Na from the bentonite and the sorption of the biand tri-metals present in the ARDs onto the bentonite. After the depletion of Na, the ion exchange reaction proceeds with the desorption of Ca and Mg from the bentonite and the sorption of cations present in the ARDs onto the bentonite layers. The depletion of Na from the bentonite and the subsequent release of Ca and Mg correlate to the sudden drop in pH and a gradual increase or equilibration of the hydraulic conductivity. It is possible to say that, after this point, hydraulic and chemical equilibrium is reached. From the overall results, the tested GCL showed acceptably low hydraulic conductivity and the potential to attenuate heavy metals present in ARDs.
Geosynthetics engineering journal, 2011
Longterm barrier performance of geosynthetic clay liners (GCLs) when exposed to acid rock draina... more Longterm barrier performance of geosynthetic clay liners (GCLs) when exposed to acid rock drainage (ARD), which is one of the most severe and expensive environmental problems facing the mining and some construction operations, was evaluated. Free swelling, sorption, and a ninemonth hydraulic conductivity tests on a needle punched GCL against an artificial ARD (pH = 3) that contained Al, Fe, Cu, Zn, As, and Pb, were conducted. Free swelling tests showed that a high metal concentration and/or a low pH negatively impacted on osmotic swelling. Sorption test results provided information about the competition among metals, and the Nabentonite capacity to sorb single metals and metalloids. Ninemonth hydraulic conductivity tests demonstrated that pH, EC and permeability changes over time, due to metal sorption/release and precipitation (physical clogging). The hydraulic conductivity remained low during the test duration and was approximately five times lower when GCL was prehydrated with water before ARD permeation (1.1x10 10 m/s) compared to the case in which prehydration and permeation were done using ARD (5.0x10 10 m/s). In each case, effluents were evaluated and breakthrough curves were constructed to get information about the GCL attenuation capacity toward metals present in ARD. Considering that bentonite (or GCLs) has the potential to retain heavy metals present in solution, showed relatively low hydraulic conductivity under even extreme conditions, and is available in many parts of the world, GCLs seem to be one possible solution for ARD mitigation.
PLOS ONE, Jul 2, 2021
Slightly acidic electrolyzed water (SAEW) was developed by Japanese companies over 20 years ago. ... more Slightly acidic electrolyzed water (SAEW) was developed by Japanese companies over 20 years ago. SAEW has the advantage of potent sterilizing action while being relatively safe. This study evaluated the potential application of SAEW in spatial disinfection. Prior to experiments involving spatial spraying, the ability of SAEW to remove seven type of microorganisms that cause food poisoning was studied in vitro. Results indicated that free chlorine in SAEW, even at a low concentration (30 mg/L), was able to remove Cladosporium cladosporioides, a typical airborne fungus that degrades food, and spores such as Bacillus subtilis, a hardy bacterium. In an experiment involving spatial spraying, 3.43 log 10 CFU/100 L of Staphylococcus epidermidis was sprayed in a room-sized space; the same space was then sprayed with SAEW. The number of settling microbes was measured and the sterilizing ability of SAEW was assessed. Results indicated that the concentration of S. epidermidis in the space was completely removed after 20 minutes of SAEW spraying. The above findings indicate that SAEW may be used to remove airborne microorganisms via spatial spraying.
Japanese Geotechnical Society Special Publication, 2016
Evaluating the factors that affect hydraulic conductivity and metal retention in geosynthetic cla... more Evaluating the factors that affect hydraulic conductivity and metal retention in geosynthetic clay liners (GCLs) becomes crucial in order to decide whether or not GCLs can be used as a barrier material in rock containments with potential for acid rock drainage (ARD) generation. This study presents a state-of-the-art review of the factors that impact the hydraulic conductivity and heavy metal retention on GCLs: effect of the type of bentonite inside GCLs, prehydration, confining pressure, pH, metal concentration, and type of metal ion in ARDs. ARDs affect the hydraulic performance of GCLs because of their characteristic low pH (usually lower than pH 3) and presence of different heavy metals and concentrations (especially the presence of divalent and trivalent metals). The retention of metals present in ARD through GCLs are governed by the pH (higher retention at pH higher than 3.5), the metals that are present in the ARD as well as the buffering capacity of the bentonite (determined by the cation exchange capacity of bentonite). Ion exchange constitutes the main mechanism for metal uptake, but other mechanisms also take place. Secondary sorption on ferrihydrite or gypsum (formed through precipitation of metals present in ARD) of metalloids such as As, which cannot be sorbed by bentonite directly, may also occur.
PeerJ, Feb 18, 2020
Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slight... more Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slightly acidic electrolyzed water (SAEW) for reduction or removal of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis was evaluated. The bactericidal activity of SAEW and sodium hypochlorite (NaOCl) against E. coli and P. aeruginosa were compared through in vitro experiments. The effectiveness of SAEW spray was tested against S. epidermidis. Results showed that SAEW had a more powerful bactericidal activity than NaOCl at the same available chlorine concentrations. For E. coli, SAEW decreased the bacterial counts from 8.4 log 10 CFU/mL to less than 3.9 log 10 CFU/mL; NaOCl with the same available chlorine of 0.5 mg/L, caused a decrease from 8.4 log 10 CFU/mL to 7.1 log 10 CFU/mL. For P. aeruginosa, SAEW caused bacterial counts to decrease from 8.5 log 10 CFU/mL to less than 4.1 log 10 CFU/mL against 8.5 log 10 CFU/mL to 6.2 log 10 CFU/mL for NaOCl with the same available chlorine of 0.5 mg/L. Spray experiments showed that 10 mg/L of SAEW spray decreased the bacterial counts of S. epidermidis from 3.7 log 10 CFU/m 3 to 2.8 log 10 CFU/m 3 , with 20 mg/L causing a reduction from 3.8 log 10 CFU/m 3 to 0 CFU/m 3. The overall findings of this study indicate that SAEW may be a promising disinfectant agent either as a solution or spray.
Applied microbiology, Dec 13, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Microbiology Research
The microalga Dunaliella salina can produce antioxidants such as glutathione, which is an essenti... more The microalga Dunaliella salina can produce antioxidants such as glutathione, which is an essential and powerful regulator of major cell functions. Changes in the glutathione concentration occur due to a microalga’s response to oxidative stress, which usually occurs when cells are exposed to environmental stressors or reach senescence. This study represents one of the few examples where changes in the glutathione concentration were tracked over the entire growth cycle of an alga. We found significant differences in the glutathione concentration depending on the growth stage. During the early lag growth phase, D. salina had relatively low levels of glutathione (190–280 µmol/1012 cell), which gradually increased as it entered the log phase (280–500 µmol/1012 cell) but then decreased as it entered the stationary phase (320–370 µmol/1012 cell). We also observed that the ratio between the reduced form of glutathione (GSH) and the oxidized form (GSSG) decreased with time, probably as a re...
Applied Biosciences
Microalgae are a source of carbohydrates, proteins and lipids. Thus, they can be considered as ra... more Microalgae are a source of carbohydrates, proteins and lipids. Thus, they can be considered as raw material to transition from current fossil fuel-based refineries to biorefineries. Microalgae harvesting is considered a major challenge in biomass production. There are several harvesting techniques, but the majority of them are either expensive or not effective. The harvesting method that we propose is sedimentation-induced by light blockage, taking advantage of the motility characteristics of certain microalgae. In this research, the halophilic microalgae Dunaliella salina was selected. Experiments were conducted under light and dark conditions to compare the sedimentation rates. Sedimentation behavior was measured by collecting data on the optical density and cell count under both light and dark conditions. The results showed that, under light conditions, the cell count in the middle of the flask decreased from 1 × 106 cell/mL to 5 × 104 cell/mL after 50 days. Under dark conditions...
<p>The “difference within laboratory” corresponds to the difference between the results obt... more <p>The “difference within laboratory” corresponds to the difference between the results obtained in the same laboratory, divided by their mean and expressed in terms of percentage.</p
<p>Whiskers represent mean ± standard deviation values.</p
<p>Whiskers represent mean ± standard deviation values.</p
Applied biosciences, May 8, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Salud, Ciencia y Tecnología, May 17, 2024
Geosynthetics engineering journal, 2012
Geosynthetics engineering journal, 2010
The capacity of geosynthetic clay liners (GCLs) to attenuate metals and metalloids such as Al, Fe... more The capacity of geosynthetic clay liners (GCLs) to attenuate metals and metalloids such as Al, Fe, Cu, Zn, As, and Pb was evaluated in this study. For this purpose, free swell, sorption, and hydraulic conductivity tests on a needlepunched geosynthetic clay liner against a pH 3 artificial acid rock drainage (ARD) were conducted. Free swelling tests showed that at high metal concentration, the swell index decreased dramatically. Sorption test results showed that Na-bentonite had high capacity to sorb metals and metalloids. Hydraulic conductivity tests showed that k was 10 times lower when GCL was prehydrated with water, before permeating with ARD. Effluents were also evaluated in each case and results showed that the GCL tested has strong attenuation capacity toward metals and metalloids present in ARD, although desorption was observed in some cases.
Applied Biosciences, Jan 10, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Soils and Foundations, Oct 1, 2019
The hydraulic and chemical compatibility of a geosynthetic clay liner (GCL), containing powdered ... more The hydraulic and chemical compatibility of a geosynthetic clay liner (GCL), containing powdered Na-bentonite, was evaluated against artificial acid rock drainage (ARD) in terms of the swell index, hydraulic conductivity and heavy metal retention. Six artificial ARDs with an approximate pH of 3 and different metal concentrations (electrical conductivity, EC, ranging between 75 and 1000 mS/m; ionic strength ranging between 8 and 400 mM) were used in the experiments. The results of free swelling tests showed that high metal concentrations (EC higher than 70 mS/m) negatively impact the swell volume by lowering it. The hydraulic conductivity of the GCL permeated with distilled water was 1.2 Â 10 À11 m/s, falling in the range of 7.9 Â 10 À12 to 1.1 Â 10 À10 m/s when prehydrated with distilled water and permeated with ARDs. The ion exchange and metal precipitation appeared to be the main mechanisms controlling the metal attenuation on the bentonite. The ion exchange mechanism starts with the release of Na from the bentonite and the sorption of the biand tri-metals present in the ARDs onto the bentonite. After the depletion of Na, the ion exchange reaction proceeds with the desorption of Ca and Mg from the bentonite and the sorption of cations present in the ARDs onto the bentonite layers. The depletion of Na from the bentonite and the subsequent release of Ca and Mg correlate to the sudden drop in pH and a gradual increase or equilibration of the hydraulic conductivity. It is possible to say that, after this point, hydraulic and chemical equilibrium is reached. From the overall results, the tested GCL showed acceptably low hydraulic conductivity and the potential to attenuate heavy metals present in ARDs.
Geosynthetics engineering journal, 2011
Longterm barrier performance of geosynthetic clay liners (GCLs) when exposed to acid rock draina... more Longterm barrier performance of geosynthetic clay liners (GCLs) when exposed to acid rock drainage (ARD), which is one of the most severe and expensive environmental problems facing the mining and some construction operations, was evaluated. Free swelling, sorption, and a ninemonth hydraulic conductivity tests on a needle punched GCL against an artificial ARD (pH = 3) that contained Al, Fe, Cu, Zn, As, and Pb, were conducted. Free swelling tests showed that a high metal concentration and/or a low pH negatively impacted on osmotic swelling. Sorption test results provided information about the competition among metals, and the Nabentonite capacity to sorb single metals and metalloids. Ninemonth hydraulic conductivity tests demonstrated that pH, EC and permeability changes over time, due to metal sorption/release and precipitation (physical clogging). The hydraulic conductivity remained low during the test duration and was approximately five times lower when GCL was prehydrated with water before ARD permeation (1.1x10 10 m/s) compared to the case in which prehydration and permeation were done using ARD (5.0x10 10 m/s). In each case, effluents were evaluated and breakthrough curves were constructed to get information about the GCL attenuation capacity toward metals present in ARD. Considering that bentonite (or GCLs) has the potential to retain heavy metals present in solution, showed relatively low hydraulic conductivity under even extreme conditions, and is available in many parts of the world, GCLs seem to be one possible solution for ARD mitigation.
PLOS ONE, Jul 2, 2021
Slightly acidic electrolyzed water (SAEW) was developed by Japanese companies over 20 years ago. ... more Slightly acidic electrolyzed water (SAEW) was developed by Japanese companies over 20 years ago. SAEW has the advantage of potent sterilizing action while being relatively safe. This study evaluated the potential application of SAEW in spatial disinfection. Prior to experiments involving spatial spraying, the ability of SAEW to remove seven type of microorganisms that cause food poisoning was studied in vitro. Results indicated that free chlorine in SAEW, even at a low concentration (30 mg/L), was able to remove Cladosporium cladosporioides, a typical airborne fungus that degrades food, and spores such as Bacillus subtilis, a hardy bacterium. In an experiment involving spatial spraying, 3.43 log 10 CFU/100 L of Staphylococcus epidermidis was sprayed in a room-sized space; the same space was then sprayed with SAEW. The number of settling microbes was measured and the sterilizing ability of SAEW was assessed. Results indicated that the concentration of S. epidermidis in the space was completely removed after 20 minutes of SAEW spraying. The above findings indicate that SAEW may be used to remove airborne microorganisms via spatial spraying.
Japanese Geotechnical Society Special Publication, 2016
Evaluating the factors that affect hydraulic conductivity and metal retention in geosynthetic cla... more Evaluating the factors that affect hydraulic conductivity and metal retention in geosynthetic clay liners (GCLs) becomes crucial in order to decide whether or not GCLs can be used as a barrier material in rock containments with potential for acid rock drainage (ARD) generation. This study presents a state-of-the-art review of the factors that impact the hydraulic conductivity and heavy metal retention on GCLs: effect of the type of bentonite inside GCLs, prehydration, confining pressure, pH, metal concentration, and type of metal ion in ARDs. ARDs affect the hydraulic performance of GCLs because of their characteristic low pH (usually lower than pH 3) and presence of different heavy metals and concentrations (especially the presence of divalent and trivalent metals). The retention of metals present in ARD through GCLs are governed by the pH (higher retention at pH higher than 3.5), the metals that are present in the ARD as well as the buffering capacity of the bentonite (determined by the cation exchange capacity of bentonite). Ion exchange constitutes the main mechanism for metal uptake, but other mechanisms also take place. Secondary sorption on ferrihydrite or gypsum (formed through precipitation of metals present in ARD) of metalloids such as As, which cannot be sorbed by bentonite directly, may also occur.
PeerJ, Feb 18, 2020
Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slight... more Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slightly acidic electrolyzed water (SAEW) for reduction or removal of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis was evaluated. The bactericidal activity of SAEW and sodium hypochlorite (NaOCl) against E. coli and P. aeruginosa were compared through in vitro experiments. The effectiveness of SAEW spray was tested against S. epidermidis. Results showed that SAEW had a more powerful bactericidal activity than NaOCl at the same available chlorine concentrations. For E. coli, SAEW decreased the bacterial counts from 8.4 log 10 CFU/mL to less than 3.9 log 10 CFU/mL; NaOCl with the same available chlorine of 0.5 mg/L, caused a decrease from 8.4 log 10 CFU/mL to 7.1 log 10 CFU/mL. For P. aeruginosa, SAEW caused bacterial counts to decrease from 8.5 log 10 CFU/mL to less than 4.1 log 10 CFU/mL against 8.5 log 10 CFU/mL to 6.2 log 10 CFU/mL for NaOCl with the same available chlorine of 0.5 mg/L. Spray experiments showed that 10 mg/L of SAEW spray decreased the bacterial counts of S. epidermidis from 3.7 log 10 CFU/m 3 to 2.8 log 10 CFU/m 3 , with 20 mg/L causing a reduction from 3.8 log 10 CFU/m 3 to 0 CFU/m 3. The overall findings of this study indicate that SAEW may be a promising disinfectant agent either as a solution or spray.
Applied microbiology, Dec 13, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Microbiology Research
The microalga Dunaliella salina can produce antioxidants such as glutathione, which is an essenti... more The microalga Dunaliella salina can produce antioxidants such as glutathione, which is an essential and powerful regulator of major cell functions. Changes in the glutathione concentration occur due to a microalga’s response to oxidative stress, which usually occurs when cells are exposed to environmental stressors or reach senescence. This study represents one of the few examples where changes in the glutathione concentration were tracked over the entire growth cycle of an alga. We found significant differences in the glutathione concentration depending on the growth stage. During the early lag growth phase, D. salina had relatively low levels of glutathione (190–280 µmol/1012 cell), which gradually increased as it entered the log phase (280–500 µmol/1012 cell) but then decreased as it entered the stationary phase (320–370 µmol/1012 cell). We also observed that the ratio between the reduced form of glutathione (GSH) and the oxidized form (GSSG) decreased with time, probably as a re...
Applied Biosciences
Microalgae are a source of carbohydrates, proteins and lipids. Thus, they can be considered as ra... more Microalgae are a source of carbohydrates, proteins and lipids. Thus, they can be considered as raw material to transition from current fossil fuel-based refineries to biorefineries. Microalgae harvesting is considered a major challenge in biomass production. There are several harvesting techniques, but the majority of them are either expensive or not effective. The harvesting method that we propose is sedimentation-induced by light blockage, taking advantage of the motility characteristics of certain microalgae. In this research, the halophilic microalgae Dunaliella salina was selected. Experiments were conducted under light and dark conditions to compare the sedimentation rates. Sedimentation behavior was measured by collecting data on the optical density and cell count under both light and dark conditions. The results showed that, under light conditions, the cell count in the middle of the flask decreased from 1 × 106 cell/mL to 5 × 104 cell/mL after 50 days. Under dark conditions...
<p>The “difference within laboratory” corresponds to the difference between the results obt... more <p>The “difference within laboratory” corresponds to the difference between the results obtained in the same laboratory, divided by their mean and expressed in terms of percentage.</p
<p>Whiskers represent mean ± standard deviation values.</p
<p>Whiskers represent mean ± standard deviation values.</p