scholarly journals SIZE EFFECT OF COPPER NANOPARTICALS ON MICROCYSTIS AERUGINOSA

2018 ◽  
Vol 16 (2) ◽  
pp. 361-367
Author(s):  
Nguyen Trung Kien ◽  
Tran Thi Thu Huong ◽  
Nguyen Hoai Chau ◽  
Dang Dinh Kim ◽  
Duong Thi Thuy
Keyword(s):  
Particle Size ◽  
Microcystis Aeruginosa ◽  
Copper Nanoparticles ◽  
Algal Blooms ◽  
Water Environment ◽  
Freshwater Ecosystems ◽  
Particle Sizes ◽  
Toxic Cyanobacteria ◽  
The Stability ◽  
Effect Of Copper

Cyanobacterial and toxins produced in cyanobacterial water blooms cause serious environmental problems which effects on freshwater ecosystems. The use of nanomaterials to control algal blooms is a new potential way for practical application due to its antibacterial as well as distinct physicochemical properties of nanomaterials. The particle size is one of the most determinant characteristics creating the different between nanomaterials and their larger bulk counterparts. However, size-dependent toxicity of nanoparticles has remained largely unknown. This study aimed to evaluate effect of three different nanoparticle sizes (d ≤ 10 nm; 30 nm ≤ d ≤ 40 nm and d ≥ 50 nm) on toxic cyanobacteria Microcystis aeruginosa. The copper nanoparticles were synthesized by electrochemical method and coated with chitosan to enhance the stability of materials in the water environment. The copper nanoparticle concentrations selected for toxic test were range from 0 (control); 0,01ppm; 0,05ppm; 0,1 ppm; 1ppm and 5 ppm. After ten days of experiment, the growth of M. aeruginosa was mainly affected at concentrations of 1 ppm and 5 ppm and there are no differences in inhibition between the particle sizes with efficiency of more than 80% in comparison to control. The highest toxicity of copper nanoparticles in M. aeruginosa was observed at particle size of 30 nm ≤ d ≤ 40 nm with EC50 = 0,73 ppm, which was respectively three to seven times less than the particle sizes of d ≥ 50 nm (EC50 = 2,62 ppm) and d ≤ 10nm (EC50 = 5,02 ppm) at the same time.

Effects of Acidity on the Stabilities of Cloudy Apple Juice

2018 ◽  
Vol 789 ◽  
pp. 26-30
Author(s):  
Dan Shi Zhu ◽  
Li Wei Wei ◽  
Xiao Jun Ren ◽  
Xue Hui Cao ◽  
He Liu ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Shelf Life ◽  
Size Distribution ◽  
Apple Juice ◽  
Influence Factor ◽  
Control Group ◽  
Particle Sizes ◽  
Stability Indexes ◽  
The Stability

Acidity is an important influence factor for juice stability. In this study, the effects of acidityon stability of cloudy apple juice were investigated. The stability indexes, such as, turbidity, cloudvalue, cloud stability, and particle size distribution (PSD) were measured at pH 2.0, 2.5, 3.0 and 3.5,along with the untreated juice (pH 3.8) as control group. The results showed that, pH has significanteffects on turbidity, chrome (C*), cloud value, and D50, D90 in PSD of cloudy apple juice. The juicehad a better stabilization at pH 2.5. At this pH condition, the turbidity, cloud value, cloud stability ofjuice was the best. In addition, at pH 2.5, the color of the juice was better, the particles were smaller,and the particle sizes were more uniform. By this study, a theoretical reference could be provided forimproving stability of cloudy apple juice and extending juice shelf life.

Formation of Oxidation-Stable Copper Nanoparticles in Water

2015 ◽  
Vol 1131 ◽  
pp. 255-259 ◽  
Author(s):  
Mary Donnabelle Balela ◽  
Kathy Lois Amores
Keyword(s):  
Particle Size ◽  
Copper Nanoparticles ◽  
Cuprous Oxide ◽  
Electroless Deposition ◽  
Cupric Oxide ◽  
Reducing Agent ◽  
Particle Sizes ◽  
Protective Agent ◽  
Cu Nanoparticles

Oxidation-stable copper (Cu) nanoparticles have been successfully prepared by electroless deposition in water at 353 K. Cupric oxide (CuO) and hydrazine (N2H4) are employed as the Cu precursor and reducing agent, respectively. The Cu nanoparticles have uniform particle sizes with average values ranging from 37 to 43 nm. The addition of gelatin has played a vital in role in controlling the particle size, agglomeration, and oxidation of Cu nanoparticles. In the absence of gelatin, both metallic Cu and cuprous oxide (Cu2O) are present in the sample, indicating incomplete reduction of the CuO. Pure metallic Cu nanoparticles with excellent oxidation and dispersability in water can only be formed when gelatin is employed as protective agent. At higher amounts of gelatin, the particle size of the Cu nanoparticles is reduced.

scholarly journals Isolation and characterization of toxic Cyanobacterial Communities distribution in Lake Tana, Amhara Regional state, Ethiopia

2019 ◽  
Author(s):  
Adugnaw Admas ◽  
Aklilue Agida ◽  
Smegnew Melese ◽  
Amare Genetu
Keyword(s):  
Microcystis Aeruginosa ◽  
Water Body ◽  
Algal Blooms ◽  
Water Bodies ◽  
Health Concern ◽  
Lake Tana ◽  
Isolation And Characterization ◽  
Run Off ◽  
Toxic Cyanobacteria ◽  
Anabaena Sp

AbstractLake Tana is the second largest lake next to Victoria Lake in Africa. This Lake is exsposed to agriculture run off, industrial and Urban waste since it has not buffer zone to protect any invading materials to the water body. The accumulation and growth of blue-green algae in water body call public attention because of its health concern. Some cyanobacterial species produce toxin microcystins and anatoxin molecules can affect the liver, kideney and nervous system of animals because the toxic molecules of released from some toxic cyanobacteria may lead the organs to fail the metabolice system. The major exposure pathways of these toxins are through drinking water and recreations including swimming. In addition, these problems happen through food web. Those cyanobacteria’a are spread and growth in diffrent water body via agriculture run off, industrial and urban wastes and other nutrient source of N and P. The main goal of this scientific study was to assess the distribution of potential toxic cyanobacteria in Lake Tana. Cyano bacterial distributions were studied in different water bodies of Lake Tana. From the water bodies that have visible algal blooms and not observed algal blooms were investigated. Identification of cyano bacteria was conducted using microscope by following appropriate procedures. In the present studied area Anabaena sp, Nostoc sp., Chlorella sp., and Microcystis aeruginosa sp. were dominantly exist. Therefore, Maybe the numbers of fishe depleted in Lake Tana due to the presence of microcystine molcule source, those are Anabaena sp.,Nostoc sp. and Microcystis aeruginosa sp.

Primary study on the feeding characteristics of a golden alga on Microcystis aeruginosa

2009 ◽  
Vol 59 (9) ◽  
pp. 1727-1732
Author(s):  
Xue Zhang ◽  
Hong-Ying Hu ◽  
Yu Hong
Keyword(s):  
Microcystis Aeruginosa ◽  
Growth Curve ◽  
Algal Blooms ◽  
Removal Rate ◽  
Morphological Characters ◽  
Primary Study ◽  
Rdna Genes ◽  
Feeding Experiments ◽  
Toxic Cyanobacteria ◽  
Short Time

A flagellate Jin821 which could feed on toxic cyanobacteria Microcystis aeruginosa was isolated, and it was identified as a species of golden alga according to its morphological characters and 18S rDNA genes. The results of feeding experiments showed that the golden alga Jin821 could make the high density (4.3 × 106 cells·mL−1) of M. aeruginosa clear in a short time (40 h), with a removal rate of 99.9%. And the microcystin (MC-LR) was also degraded effectively at the same time, with a removal rate of 82.7% of 114 μg/L in 40 h. The growth curve of Jin821 was in ‘S’ style, with four phases of lag, log, stationary and decline. When M. aeruginosa was cleaned out, Jin821 would decline in number and slowed down in movement. In summary, the golden alga Jin821 can be a potential biological way to control blue algal blooms in the future.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

Phosphorus transport in saturated slag columns: experiments and mathematical models

1996 ◽  
Vol 34 (1-2) ◽  
pp. 153-160 ◽  
Author(s):  
S. H. Lee ◽  
S. Vigneswaran ◽  
K. Bajracharya
Keyword(s):  
Mathematical Models ◽  
Sorption Capacity ◽  
Algal Blooms ◽  
Sandy Loam ◽  
Dynamic Condition ◽  
Water Environment ◽  
Breakthrough Curves ◽  
Column Experiments ◽  
Phosphorus Transport ◽  
Waste Products

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from a steel industry as adsorbing indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical nonequilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbents and it is proportional to the sorption capacity of them.

scholarly journals Effect of particle size on phytochemical composition and antioxidant properties of Sargassum cristaefolium ethanol extract

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Prasedya ◽  
A. Frediansyah ◽  
N. W. R. Martyasari ◽  
B. K. Ilhami ◽  
A. S. Abidin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Ethanol Extract ◽  
Total Phenolic ◽  
Particle Sizes ◽  
Epicatechin Gallate ◽  
Particle Size Reduction ◽  
Phytochemical Composition

AbstractSample particle size is an important parameter in the solid–liquid extraction system of natural products for obtaining their bioactive compounds. This study evaluates the effect of sample particle size on the phytochemical composition and antioxidant activity of brown macroalgae Sargassum cristaefolium. The crude ethanol extract was extracted from dried powders of S.cristeafolium with various particle sizes (> 4000 µm, > 250 µm, > 125 µm, > 45 µm, and < 45 µm). The ethanolic extracts of S.cristaefolium were analysed for Total Phenolic Content (TPC), Total Flavonoid Content (TFC), phenolic compound concentration and antioxidant activities. The extract yield and phytochemical composition were more abundant in smaller particle sizes. Furthermore, the TPC (14.19 ± 2.08 mg GAE/g extract to 43.27 ± 2.56 mg GAE/g extract) and TFC (9.6 ± 1.8 mg QE/g extract to 70.27 ± 3.59 mg QE/g extract) values also significantly increased as particle sizes decreased. In addition, phenolic compounds epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and Epigallocatechin gallate (EGCG) concentration were frequently increased in samples of smaller particle sizes based on two-way ANOVA and Tukey’s multiple comparison analysis. These results correlate with the significantly stronger antioxidant activity in samples with smaller particle sizes. The smallest particle size (< 45 µm) demonstrated the strongest antioxidant activity based on DPPH, ABTS, hydroxyl assay and FRAP. In addition, ramp function graph evaluates the desired particle size for maximum phytochemical composition and antioxidant activity is 44 µm. In conclusion, current results show the importance of particle size reduction of macroalgae samples to increase the effectivity of its biological activity.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

scholarly journals Investigation of the kinetics of spontaneous combustion of the major coal seam in Dahuangshan mining area of the Southern Junggar coalfield, Xinjiang, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Shen ◽  
Qiang Zeng
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Coal Seam ◽  
Spontaneous Combustion ◽  
Heating Temperature ◽  
Characteristic Temperature ◽  
Mining Area ◽  
Particle Sizes ◽  
Coal Oxidation ◽  
Increasing Temperature

AbstractIn the present paper, with using diverse methods (including the SEM, the XRD, the TPO, the FTIR, and the TGA) , the authors analysed samples of the major coal seam in Dahuangshan Mining area with different particle sizes and with different heated temperatures (from 50 to 800 °C at regular intervals of 50 °C). The results from SEM and XRD showed that high temperature and high number of pores, fissures, and hierarchical structures in the coal samples could facilitate oxidation reactions and spontaneous combustion. A higher degree of graphitization and much greater number of aromatic microcrystalline structures facilitated spontaneous combustion. The results from TPO showed that the oxygen consumption rate of the coal samples increased exponentially with increasing temperature. The generation rates of different gases indicated that temperatures of 90 °C or 130 °C could accelerate coal oxidation. With increasing temperature, the coal oxidation rate increased, and the release of gaseous products was accelerated. The FTIR results showed that the amount of hydroxide radicals and oxygen-containing functional groups increased with the decline in particle size, indicating that a smaller particle size may facilitate the oxidation reaction and spontaneous combustion of coal. The absorbance and the functional group areas at different particle sizes were consistent with those of the heated coal samples, which decreased as the temperature rose. The results from TGA showed that the characteristic temperature T3 declined with decreasing particle size. After the sample with 0.15–0.18 mm particle size was heated, its carbon content decreased, and its mineral content increased, inhibiting coal oxidation. This result also shows that the activation energy of the heated samples tended to increase at the stage of high-temperature combustion with increasing heating temperature.

scholarly journals First report of detection of microcystins in farmed mediterranean mussels Mytilus galloprovincialis in Thermaikos gulf in Greece

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Maria P. Kalaitzidou ◽  
Christina I. Nannou ◽  
Dimitra A. Lambropoulou ◽  
Konstantinos V. Papageorgiou ◽  
Alexandros M. Theodoridis ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
High Performance ◽  
Mytilus Galloprovincialis ◽  
Elisa Method ◽  
Northern Greece ◽  
Temporal And Spatial Distribution ◽  
Coastal Marine ◽  
Toxic Cyanobacteria ◽  
Comparison Of The Results

Abstract Background Microcystins are emerging marine biotoxins, produced by potentially toxic cyanobacteria. Their presence has been reported in aquatic animals in Greek freshwater, while data are few in marine environments. Since the climate change induces eutrophication and harmful algal blooms in coastal marine ecosystems affecting the public health, further research on microcystins’ presence in marine waters is required. The aim of this study was to examine the potential presence of microcystins in mussels Mytilus galloprovincialis in the largest farming areas in Thermaikos gulf, in Northern Greece, and to investigate their temporal and spatial distribution, adding to the knowledge of microcystins presence in Greek Mediterranean mussels. Results A 4-year microcystins’ assessment was conducted from 2013 to 2016, in farmed Mediterranean mussels M. galloprovincialis, in five sampling areas in Thermaikos gulf, in northern Greece, where the 90% of the Greek mussels’ farming activities is located. The isolation of potentially toxic cyanobacteria was confirmed by molecular methods. An initial screening was performed with a qualitative and quantitative direct monoclonal (DM) ELISA and results above 1 ng g−1 were confirmed for the occurrence of the most common microcystins-RR, -LR and -YR, by Ultra High Performance Liquid Chromatography (UHPLC) coupled with a high- resolution mass spectrometer (HRMS) (Orbitrap analyzer). Microcystin-RR and microcystin-LR were detected, while the intensity of microcystin-YR was below the method detection limit. Most samples that exhibited concentrations above 1 ng g-1 were detected during the warm seasons of the year and especially in spring. Results indicated an overestimation of the ELISA method, since concentrations ranged between 0.70 ± 0.15 ng g−1 and 53.90 ± 3.18 ng g−1, while the confirmation denoted that the levels of microcystins were 6 to 22 times lower. Conclusions Microcystin-RR and microcystin-LR were detected for the first time in mussel M. galloprovincialis, harvested from farms in Thermaikos gulf, in Central Macedonia, Greece. Their presence was linked to potentially toxic cyanobacteria. Bioaccumulation was observed in digestive gland, while the concentrations in muscles were found extremely low. Samples with levels above 1 ng g−1 were observed mostly during spring, confirming the seasonal distribution of microcystins. The comparison of the results by the ELISA and the LC-Orbitrap MS method indicated an overestimation of concentration by the ELISA method.

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