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Artigos de revistas sobre o tema "Gac"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 24 de agosto de 2024

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1

Kamboj, Nitin, e Mohrana Choudhary. "Impact of solid waste disposal on ground water quality near Gazipur dumping site, Delhi, India". Journal of Applied and Natural Science 5, n.º 2 (1 de dezembro de 2013): 306–12. http://dx.doi.org/10.31018/jans.v5i2.322.

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The present study was carried out to study the impact of domestic wastes disposal on ground water quality at Delhi, India. Ground water is one of the major sources of drinking water in arid and semi-arid regions. Ground water quality data and its distributions are important for the purpose of planning and management. The samples of ground water were collected and analyzed for various physico-chemical parameters viz. conductivity, total dissolved solids (TDS), alkalinity, total hardness, calcium, magnesium, chloride, sulphate, nitrate, phosphate,fluoride, sodium and potassium. Among these parameters, TDS were found higher 1400, 1068, 1524, 1656, 840, 1106, 1540, 1330, 1900, 1960, 1914, 2061 mg/l at all the Ga1,Ga2, Ga3, Ga4, Ga5, Ga6, Ga7, Ga8, Ga9, Ga10, Ga11, Ga12, Ga13, Ga14, Ga15, Ga16 sampling sites respectively. TDS were observed beyond the desirable limits of BIS at all the sampling sites. Maximum value of TDS (2061 mg/l) was found at the sampling site Ga12 while the minimum value of TDS (1061 mg/l) was found at the sampling site Ga2. Maximum value of chloride (560 mg/l) wasfound at sampling site Ga4, while the minimum value of chloride (60 mg/l) was found at sampling site Ga5 and rest all other parameters were found within permissible limit. The present study concluded that the chloride and TDS in water samples were above to the desirable limit and below to the permissible limit of BIS and rest all other parameters were within desirable limit.

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2

van den Broek, Daan, Thomas F. C. Chin-A-Woeng, Guido V. Bloemberg e Ben J. J. Lugtenberg. "Role of RpoS and MutS in phase variation of Pseudomonas sp. PCL1171". Microbiology 151, n.º 5 (1 de maio de 2005): 1403–8. http://dx.doi.org/10.1099/mic.0.27777-0.

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Pseudomonas sp. strain PCL1171 undergoes reversible colony phase variation between opaque phase I and translucent phase II colonies, which is dependent on spontaneous mutations in the regulatory genes gacA and gacS. Mutation of the mutS gene and constitutive expression of rpoS increases the frequency at which gac mutants appear 1000- and 10-fold, respectively. Experiments were designed to study the relationship between gacS, rpoS and mutS. These studies showed that (i) a functional gac system is required for the expression of rpoS, (ii) RpoS suppresses the expression of mutS and therefore increases the frequency of gac mutants, and (iii) upon mutation of rpoS and gacS, the expression of mutS is increased. Mutation of gacS abolishes suppression of mutS expression in stationary growth, suggesting that additional gac-dependent factors are involved in this suppression. In conclusion, inefficient mutation repair via MutS, of which the expression is influenced by gacA/S itself and by rpoS in combination with other factors, contributes to the high frequency of mutations accumulating in gacA/S. The role of RpoS in the growth advantage of a gac mutant was analysed, and mutation of rpoS only reduced the length of the lag phase, but did not affect the growth rate, suggesting a role for both RpoS and a reduction of metabolic load in the growth advantage of a gac mutant.

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3

Kim, Taehoon, e Byungryul An. "Effect of Hydrogen Ion Presence in Adsorbent and Solution to Enhance Phosphate Adsorption". Applied Sciences 11, n.º 6 (20 de março de 2021): 2777. http://dx.doi.org/10.3390/app11062777.

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In this paper, the effect of hydrogen ions on the adsorption onto granular activated carbon (GAC) with the inorganic contaminant phosphate, which exists as a form of four species depending on the solution pH, is investigated. Various batch isotherm and kinetic experiments were conducted in an initial pH 4 as an acid, a pH 7 as neutral, and a pH 9 solution as a base for the GAC conditioned with deionized water and hydrochloric acid, referred to as GAC and GACA, respectively. The physical properties, such as the total surface area, pore volume, pore size distribution, and weight of the element, obtained from Brunauer–Emmett–Teller (BET) and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM–EDX) represent no significant differences. However, the hydrochloric acid (HCl) condition results in an alteration of the pH of the point of zero charge from 4.5 to 6.0. The optimized initial pH was determined as being acid for the GAC and as being neutral for the GACA. According to the Langmuir isotherm, the relatively high Qm was obtained as being acid for the GAC and clearly distinguishes the pH effect as being the base for the GACA. An attempt was made to assess the adsorption mechanism using the pseudo-first-order (PFO), the pseudo-second-order (PSO), and the intraparticle diffusion models. The higher R2 for the PSO in the entire pH range indicated that chemisorption was predominant for phosphate adsorption, and the pH did not change the adsorption mechanism. A prolonged Bed Volume (BV) for the GACA demonstrated that the hydrogen ions on the surface of the GAC enhanced phosphate adsorption.

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4

Lin, Shih-Shun, Hui-Wen Wu, Fuh-Jyh Jan, Roger F. Hou e Shyi-Dong Yeh. "Modifications of the Helper Component-Protease of Zucchini yellow mosaic virus for Generation of Attenuated Mutants for Cross Protection Against Severe Infection". Phytopathology® 97, n.º 3 (março de 2007): 287–96. http://dx.doi.org/10.1094/phyto-97-3-0287.

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A nonpathogenic mild strain is essential for control of plant viruses by cross protection. Three amino acid changes, Arg180→Ile180 (GA mutation), Phe205→Leu205 (GB mutation), and Glu396→Asn396 (GC mutation), of the conserved motifs of the helper component-protease (HC-Pro) of a severe strain TW-TN3 of Zucchini yellow mosaic virus (ZYMV), a member of the genus Potyvirus, were generated from an infectious cDNA clone that carried a green fluorescent protein reporter. The infectivity of individual mutants containing single, double, or triple mutations was assayed on local and systemic hosts. On Chenopodium quinoa plants, the GB mutant induced necrotic lesions; the GA, GC, and GBC mutants induced chlorotic spots; and the GAB and GAC mutants induced local infection only visualized by fluorescence microscopy. On squash plants, the GA, GB, GC, and GBC mutants caused milder mosaic; the GAC mutant induced slight leaf mottling followed by recovering; and the GAB mutant did not induce conspicuous symptoms. Also, the GAC mutant, but not the GAB mutant, conferred complete cross protection against the parental virus carrying a mite allergen as a reporter. When tested on transgene-silenced transgenic squash, the ability of posttranscriptional gene silencing suppression of the mutated HC-Pro of GAC was not significantly affected. We concluded that the mutations of the HC-Pro of ZYMV reduce the degrees of pathogenicity on squash and also abolish the ability for eliciting the hypersensitive reaction on C. quinoa, and that the mutant GAC is a useful mild strain for cross protection.

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5

Takeuchi, Kasumi, Kosumi Yamada e Dieter Haas. "ppGpp Controlled by the Gac/Rsm Regulatory Pathway Sustains Biocontrol Activity in Pseudomonas fluorescens CHA0". Molecular Plant-Microbe Interactions® 25, n.º 11 (novembro de 2012): 1440–49. http://dx.doi.org/10.1094/mpmi-02-12-0034-r.

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In Pseudomonas fluorescens CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway is instrumental for secondary metabolism and biocontrol of root pathogens via the expression of regulatory small RNAs (sRNAs). Furthermore, in strain CHA0, an imbalance in the Krebs cycle can affect the strain's ability to produce extracellular secondary metabolites, including biocontrol factors. Here, we report the metabolome of wild-type CHA0, a gacA-negative mutant, which has lost Gac/Rsm activities, and a retS-negative mutant, which shows strongly enhanced Gac/Rsm-dependent activities. Capillary electrophoresis-based metabolomic profiling revealed that the gacA and retS mutations had opposite effects on the intracellular levels of a number of central metabolites, suggesting that the Gac/Rsm pathway regulates not only secondary metabolism but also primary metabolism in strain CHA0. Among the regulated metabolites identified, the alarmone guanosine tetraphosphate (ppGpp) was characterized in detail by the construction of relA (for ppGpp synthase) and spoT (for ppGpp synthase/hydrolase) deletion mutants. In a relA spoT double mutant, ppGpp synthesis was completely abolished, the expression of Rsm sRNAs was attenuated, and physiological functions such as antibiotic production, root colonization, and plant protection were markedly diminished. Thus, ppGpp appears to be essential for sustaining epiphytic fitness and biocontrol activity of strain CHA0.

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6

Driscoll, William W., John W. Pepper, Leland S. Pierson e Elizabeth A. Pierson. "Spontaneous Gac Mutants of Pseudomonas Biological Control Strains: Cheaters or Mutualists?" Applied and Environmental Microbiology 77, n.º 20 (26 de agosto de 2011): 7227–35. http://dx.doi.org/10.1128/aem.00679-11.

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ABSTRACTBacteria rely on a range of extracellular metabolites to suppress competitors, gain access to resources, and exploit plant or animal hosts. The GacS/GacA two-component regulatory system positively controls the expression of many of these beneficial external products in pseudomonad bacteria. Natural populations often contain variants with defective Gac systems that do not produce most external products. These mutants benefit from a decreased metabolic load but do not appear to displace the wild type in nature. How could natural selection maintain the wild type in the presence of a mutant with enhanced growth? One hypothesis is that Gac mutants are “cheaters” that do not contribute to the public good, favored within groups but selected against between groups, as groups containing more mutants lose access to ecologically important external products. An alternative hypothesis is that Gac mutants have a mutualistic interaction with the wild type, so that each variant benefits by the presence of the other. In the biocontrol bacteriumPseudomonas chlororaphisstrain 30-84, Gac mutants do not produce phenazines, which suppress competitor growth and are critical for biofilm formation. Here, we test the predictions of these alternative hypotheses by quantifying interactions between the wild type and the phenazine- and biofilm-deficient Gac mutant within growing biofilms. We find evidence that the wild type and Gac mutants interact mutualistically in the biofilm context, whereas a phenazine-defective structural mutant does not. Our results suggest that the persistence of alternative Gac phenotypes may be due to the stabilizing role of local mutualistic interactions.

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7

Tewfik, Nazih, Samir Abdelmoaty, Barry L. Smith e Paulo Johann. "GAC Spotlight". Leading Edge 23, n.º 10 (outubro de 2004): 990–92. http://dx.doi.org/10.1190/tle23100990.1.

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8

Burianyk, Mike, John M. Howie, Ezeanyagu Ifeanyichukwu, A. G. Onwuemesi, Hermes Malcotti, Adrián Rodríguez Herrera, Dave Pitcher e Susan Henley. "GAC Spotlight". Leading Edge 24, n.º 1 (janeiro de 2005): 44–47. http://dx.doi.org/10.1190/tle24010044.1.

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9

Burianyk, Mike, James Sun e David Zinzer. "GAC Spotlight". Leading Edge 24, n.º 4 (abril de 2005): 398–400. http://dx.doi.org/10.1190/tle24040398.1.

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10

Pitcher, Dave, Aldo Vesnaver, Peter Attewell e Mike Burianyk. "GAC Spotlight". Leading Edge 24, n.º 6 (junho de 2005): 594–96. http://dx.doi.org/10.1190/tle24060594.1.

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11

Burianyk, Michael, Constantin Sava, Maurizio Fedi, Maxim Yu Podberezhny, Consuelo Garcia Moyonero, Neeraj Duhoon, Kemalmert ÖNAL, Honey Malinga e David Zinzer. "GAC Spotlight". Leading Edge 24, n.º 8 (agosto de 2005): 812–15. http://dx.doi.org/10.1190/tle24080812.1.

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12

Abdelmoaty, Samir, e David Pitcher. "GAC Spotlight". Leading Edge 24, n.º 10 (outubro de 2005): 1006–7. http://dx.doi.org/10.1190/tle24101006.1.

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13

Bo, Zhao. "GAC Spotlight". Leading Edge 24, n.º 11 (novembro de 2005): 1146–48. http://dx.doi.org/10.1190/tle24111146.1.

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14

Burianyk, Michael, e Andrei Bocin. "GAC Spotlight". Leading Edge 25, n.º 1 (janeiro de 2006): 42–43. http://dx.doi.org/10.1190/tle25010042.1.

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15

Burianyk, Michael, Konstantin Osypov, Evgeny Landa e Vladimir Tcheverda. "GAC Spotlight". Leading Edge 25, n.º 5 (maio de 2006): 659–62. http://dx.doi.org/10.1190/tle25050659.1.

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16

Vesnaver, Aldo, Vaughn Ball, Cezar Iacob e Andrei Bocin. "GAC Spotlight". Leading Edge 25, n.º 6 (junho de 2006): 787–88. http://dx.doi.org/10.1190/tle25060787.1.

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17

Bora, Bhagwan Singh, K. Sandhya Rani e T. Harinarayana. "GAC Spotlight". Leading Edge 25, n.º 7 (julho de 2006): 812–15. http://dx.doi.org/10.1190/tle25070812.1.

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18

Burianyk, Michael. "GAC Spotlight". Leading Edge 25, n.º 8 (agosto de 2006): 1014–15. http://dx.doi.org/10.1190/tle25081014.1.

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19

Cox, Barbara, e Markku Peltoniemi. "GAC Spotlight". Leading Edge 26, n.º 1 (janeiro de 2007): 94–95. http://dx.doi.org/10.1190/tle26010094.1.

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20

Chopra, Satinder. "GAC Spotlight". Leading Edge 26, n.º 2 (fevereiro de 2007): 238–40. http://dx.doi.org/10.1190/tle26020238.1.

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21

Uchida, Toshihiro, e Tadeusz Ulrych. "GAC Spotlight". Leading Edge 26, n.º 3 (março de 2007): 368–70. http://dx.doi.org/10.1190/tle26030368.1.

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22

Yanchak, Dennis, Aleksei Shevchenko e Konstantin Osypov. "GAC Spotlight". Leading Edge 26, n.º 4 (abril de 2007): 532–33. http://dx.doi.org/10.1190/tle26040532.1.

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23

Bridle, Ralph M., William L. Abriel e Steve Chang. "GAC Spotlight". Leading Edge 26, n.º 6 (junho de 2007): 787–90. http://dx.doi.org/10.1190/tle26060787.1.

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24

Pitcher, David, Evgeny Landa, Sven Treitel, Tad Ulrych e Yoram Shoham. "GAC SPOTLIGHT". Leading Edge 26, n.º 7 (julho de 2007): 904–6. http://dx.doi.org/10.1190/tle26070904.1.

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25

Vesnaver, Aldo, Aldo Vesnaver, Danila Tverdokhlebov e Sergey Gorbachev. "GAC Spotlight". Leading Edge 26, n.º 9 (setembro de 2007): 1208–12. http://dx.doi.org/10.1190/tle26091208.1.

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26

Bouma, Bastiaan. "GAC Spotlight". Leading Edge 27, n.º 5 (maio de 2008): 684–86. http://dx.doi.org/10.1190/tle27050684.1.

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27

Burianyk, Mike, Vladislav Kuznetsov e Bastiaan Bouma. "GAC Spotlight". Leading Edge 27, n.º 6 (junho de 2008): 806–10. http://dx.doi.org/10.1190/tle27060806.1.

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28

Vesnaver, Aldo. "GAC Spotlight". Leading Edge 27, n.º 8 (agosto de 2008): 1060–62. http://dx.doi.org/10.1190/tle27081060.1.

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29

Bouma, Bastiaan. "GAC Spotlight". Leading Edge 28, n.º 2 (fevereiro de 2009): 249. http://dx.doi.org/10.1190/tle28020249.1.

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30

Terekhova, Pam. "GAC Spotlight". Leading Edge 28, n.º 5 (maio de 2009): 608. http://dx.doi.org/10.1190/tle28050608.1.

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31

Takeuchi, Kasumi. "GABA, A Primary Metabolite Controlled by the Gac/Rsm Regulatory Pathway, Favors a Planktonic Over a Biofilm Lifestyle in Pseudomonas protegens CHA0". Molecular Plant-Microbe Interactions® 31, n.º 2 (fevereiro de 2018): 274–82. http://dx.doi.org/10.1094/mpmi-05-17-0120-r.

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In Pseudomonas protegens CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway is crucial for the expression of secondary metabolism and the biological control of fungi, nematodes, and insects. Based on the findings of a previous metabolomic study, the role of intracellular γ-aminobutyrate (GABA) as a potential signal in the Gac/Rsm pathway was investigated herein. The function and regulation of a gabDT (c01870-c01880) gene cluster in strain CHA0 were described. The gabT gene encoded GABA transaminase (GABAT) and enabled the growth of the bacterium on GABA, whereas the upstream gabD gene (annotated as a gene encoding succinic semialdehyde dehydrogenase) had an unknown function. A gacA mutant exhibited low GABAT activity, leading to the markedly greater intracellular accumulation of GABA than in the wild type. In the gacA mutant, the RsmA and RsmE proteins caused translational gabD repression, with concomitant gabT repression. Due to very low GABAT activity, the gabT mutant accumulated GABA to high levels. This trait promoted a planktonic lifestyle, reduced biofilm formation, and favored root colonization without exhibiting the highly pleiotropic gacA phenotypes. These results suggest an important role of GABA in the Gac/Rsm-regulated niche adaptation of strain CHA0 to plant roots.

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32

Mardiah, Triana, Depison Depison e Helmi Ediyanto. "Phenotype Diversity and Gene Myostatin (MSTN) of Bangkok Chicken using PCR-RFLP". Buletin Peternakan 45, n.º 4 (30 de novembro de 2021): 233. http://dx.doi.org/10.21059/buletinpeternak.v45i4.68968.

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This study aims to characterize the phenotype and determine the diversity of the Myostatin (MSTN) gene at Bangkok chickens using the Polymerase Chain Reaction- Restriction Fragment Length Polymorphism (PCR-RFLP) method. This study used 50 Bangkok chicken blood samples taken from the axillary vein on the wing. DNA was extracted using the protocol Genomic DNA Purification Kit from Promega and then amplified by PCR (polymerase chain reaction) using a pair of primers F: 5'GGT TTT GAC GAC ATG AGC CT3' R: 5'CAG GTG GAA TGT CAT GCA GA3' with product length 955 bp. Amplification products were cut using restriction enzyme MboI with cutting site ↓GATC. MSTN|MboI fragments of the Bangkok chicken were electrophoresed using 2% agarose gel and visualized using doc gel. The average difference test (T-test) on body weight and weight gain of Bangkok chickens from DOC to 3 months by gender. Polymorphism analysis includes allele frequency and genotype. Male and female Bangkok chickens have low phenotype diversity. The MSTN|MboI gene fragment is monomorphic with band positions of 492 bp, 244 bp, and 219 bp resulting in a genotype of ++, and there is one type of allele with a + allele frequency of 100%.

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33

Ondon, Brim Stevy, Bing Sun, Zhi Yu Yan, Xiao Mei Zhu e Hui Liu. "Microwave Preparation of Modified Activated Carbons for Phenol Adsorption in Aqueous Solution". Advanced Materials Research 726-731 (agosto de 2013): 1883–89. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.1883.

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Microwave energy was used to prepare modified activated carbons (GAC, GAC/MW, GAC/Ni, and GAC/Cu). The modified activated carbons were used for phenol adsorption in aqueous solution. The adsorption conditions were optimized. Adsorption capacities of the different modified activated carbons were evaluated. The effect of microwave pretreatment of activated carbons was investigated. A comparative study on the activated carbons adsorption capacities was also investigated. Under optimal conditions the results showed that there was no obvious effect on activated carbons adsorption when rising temperature and pH during the adsorption process. Stirring has a very high effect on the activated carbons adsorption capacity. The adsorption capacity of the modified activated carbons reaches 95%. MW/GAC, GAC/Ni and GAC/Cu adsorptive capacity was higher compared to the Granulated Activated Carbon (GAC) used as received. GAC treated with microwave energy has highest adsorption capacity. The adsorption capacity of GAC loaded with ion Ni2+ is higher than the activated carbon loaded with Cu2+. The untreated GAC has the lowest adsorption capacity. These results can be explained by the effect of microwave irradiation on GAC.The activated carbon loaded with Ni2+ adsorbs more microwave energy than the GAC loaded with Cu2+.

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34

Shiraiwa, Nobutaka, Kaori Kikuchi, Ichiro Honda, Masayoshi Shigyo, Hiroko Yamazaki, Daisuke Tanaka, Kenji Tanabe e Akihiro Itai. "Characterization of Endogenous Gibberellins and Molecular Cloning of a Putative Gibberellin 3-Oxidase Gene in Bunching Onion". Journal of the American Society for Horticultural Science 136, n.º 6 (novembro de 2011): 382–88. http://dx.doi.org/10.21273/jashs.136.6.382.

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To clarify the role of gibberellin (GA) in the growth of bunching onion (Allium fistulosum), identification of endogenous GAs and expression analysis of a putative gibberellin 3-oxidase (AfGA3ox1) were conducted. GA1, GA3, GA4, GA9, GA20, and GA34 were identified with levels of GA4 and GA9 being higher than those of GA1, GA3, and GA20. The young seedlings were clearly elongated by exogenous GA4 treatment but not by GA3. These results indicate that the 13-non-hydroxylation pathway of GA biosynthesis may be predominant in shoots with GA4 playing an important role in the growth of bunching onion. Expression of AfGA3ox1 was higher in leaf sheaths than leaf blades during vegetative growth. In reproductive organs, expression of AfGA3ox1 was higher at early and middle development stages in the stalks but was detected at a late development stage in the umbels. AfGA3ox1 was mapped on chromosome 7A from shallot, a bunching onion-related species.

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Ridwan Fahmi, Muhammad, M. N. Nasruddin, Che Zulzikrami Azner Abidin e M. Ali Umi Fazara. "Adsorption of Reactive Red 120 by Using Regenerated Spent Carbon". Applied Mechanics and Materials 754-755 (abril de 2015): 671–75. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.671.

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In this study the performance of regenerated spent carbon for azo dye removal was evaluated in batch and continuous column. The spent carbon was generated by thermal method through pyrolysis process and chemical method by using NaOH 6.0 M solution. Reactive Red 120 (RR120) was selected as a model of azo dye due to its common application in the industries. The regeneration of spent granular activated carbon (GAC) by pyrolysis could produce adsorbent that has the adsorption capacity closer to new GAC. The result indicated that paralysed GAC could potentially apply to replace new GAC for RR120 adsorption. In addition, the continuous adsorption operation in mini column test confirmed that the order of adsorption capacity of each GAC is as follows: new GAC, pirolysed GAC, chemical treated GAC and spent GAC.

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36

Zha, Daiming, Li Xu, Houjin Zhang e Yunjun Yan. "The Two-Component GacS-GacA System ActivateslipATranslation by RsmE but Not RsmA in Pseudomonas protegens Pf-5". Applied and Environmental Microbiology 80, n.º 21 (15 de agosto de 2014): 6627–37. http://dx.doi.org/10.1128/aem.02184-14.

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ABSTRACTInPseudomonasspp., the Gac-Rsm signal transduction system is required for the production of lipases. The current model assumes that the system induces lipase gene transcription mediated through the quorum-sensing (QS) system. However, there are no reports of a QS system based uponN-acyl homoserine lactones or the regulation of lipase gene expression inPseudomonas protegens. In this study, we investigated the regulatory mechanism acting onlipAexpression activated by the Gac-Rsm system inP. protegensPf-5 through deletion and overexpression ofgacA, overexpression ofrsmAorrsmE, expression of variouslacZfusions, reverse transcription-PCR analysis, and determination of whole-cell lipase activity. The results demonstrated that the GacS-GacA (GacS/A) system activateslipAexpression at both the transcriptional and the translational levels but that the translational level is the key regulatory pathway. Further results showed that the activation oflipAtranslation by the GacS/A system is mediated through RsmE, which inhibitslipAtranslation by binding to the ACAAGGAUGU sequence overlapping the Shine-Dalgarno (SD) sequence oflipAmRNA to hinder the access of the 30S ribosomal subunit to the SD sequence. Moreover, the GacS/A system promoteslipAtranscription through the mediation of RsmA inhibitinglipAtranscription via an unknown pathway. Besides the transcriptional repression, RsmA mainly activateslipAtranslation by negatively regulatingrsmEtranslation. In summary, inP. protegensPf-5, the Gac-RsmE system mainly and directly activateslipAtranslation and the Gac-RsmA system indirectly enhanceslipAtranscription.

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Ando, A., Y. Kajiyama e N. Takigawa. "Study on deterioration of water treatment capability of granular activated carbon (GAC) in Osaka City". Water Supply 6, n.º 2 (1 de março de 2006): 245–51. http://dx.doi.org/10.2166/ws.2006.076.

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To supply safe, good-quality tap water, Osaka Municipal Waterworks Bureau (OMWW) introduced an advanced water treatment system that incorporates ozonation and granular activated carbon (GAC) treatment into conventional treatment processes. By March 2000, all water purification plants in Osaka City were equipped with advanced water treatment facilities. This new treatment system has successfully removed odours and flavor and reduced trihalomethane. GAC treatment, the last stage of the water treatment, plays a vital role in removing organic matter in water, in conjunction with ozonation. However, GAC performance changes over time. To optimize the GAC effect, it is essential to conduct proper GAC management based on a thorough grasp of the change patterns of GAC performance. To determine GAC's water treatment capability, we analyzed data on 69 water quality items; obtained from past plant tests and chemical substance addition experiments using GAC actually used in the purification plants. Analysis revealed the deterioration patterns and time of GAC performance. By considering physical properties and economic factors as well as deterioration patterns of GAC performance, it is possible to establish an optimal GAC management system. This paper describes the findings obtained from the study on GAC water treatment performance conducted by OMWW.

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Niu, Jia, Ikuro Kasuga, Futoshi Kurisu e Hiroaki Furumai. "Effects of Backwashing on Granular Activated Carbon with Ammonium Removal Potential in a Full-Scale Drinking Water Purification Plant". Water 10, n.º 12 (11 de dezembro de 2018): 1830. http://dx.doi.org/10.3390/w10121830.

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Granular activated carbon (GAC) has been widely introduced to advanced drinking water purification plants to remove organic matter and ammonium. Backwashing, which is the routine practice for GAC maintenance, is an important operational factor influencing the performance of GAC and its microbial biomass. In this study, the effects of backwashing on the ammonium removal potential of GAC were evaluated. In addition, abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) on GAC were analyzed. GAC samples before and after backwashing were collected from a full-scale drinking water purification plant. Samplings were conducted before and after implementation of prechlorination of raw water. The results showed that the ammonium removal potential of the GAC increased by 12% after backwashing before prechlorination (p < 0.01). After implementing the prechlorination, the ammonium removal potential of the GAC decreased by 12% even after backwashing (p < 0.01). The AOA was predominant on the GAC in the two samplings. Regardless of prechlorination, the amounts of the AOA and the AOB remained at the same level before and after backwashing. Analysis of the backwashing water indicated that the amounts of the AOA and AOB washed out from the GAC were negligible (0.08%–0.26%) compared with their original amounts on the GAC. These results revealed the marginal role of backwashing on the biomass of ammonia oxidizers on GAC. However, the results also revealed that backwashing could have a negative impact on the ammonium removal potential of GAC during prechlorination.

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Martï¿½nez-Granero, Francisco, Rafael Rivilla e Marta Martï¿½n. "Rhizosphere Selection of Highly Motile Phenotypic Variants of Pseudomonas fluorescens with Enhanced Competitive Colonization Ability". Applied and Environmental Microbiology 72, n.º 5 (maio de 2006): 3429–34. http://dx.doi.org/10.1128/aem.72.5.3429-3434.2006.

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ABSTRACT Phenotypic variants of Pseudomonas fluorescens F113 showing a translucent and diffuse colony morphology show enhanced colonization of the alfalfa rhizosphere. We have previously shown that in the biocontrol agent P. fluorescens F113, phenotypic variation is mediated by the activity of two site-specific recombinases, Sss and XerD. By overexpressing the genes encoding either of the recombinases, we have now generated a large number of variants (mutants) after selection either by prolonged laboratory cultivation or by rhizosphere passage. All the isolated variants were more motile than the wild-type strain and appear to contain mutations in the gacA and/or gacS gene. By disrupting these genes and complementation analysis, we have observed that the Gac system regulates swimming motility by a repression pathway. Variants isolated after selection by prolonged cultivation formed a single population with a swimming motility that was equal to the motility of gac mutants, being 150% more motile than the wild type. The motility phenotype of these variants was complemented by the cloned gac genes. Variants isolated after rhizosphere selection belonged to two different populations: one identical to the population isolated after prolonged cultivation and the other comprising variants that besides a gac mutation harbored additional mutations conferring higher motility. Our results show that gac mutations are selected both in the stationary phase and during rhizosphere colonization. The enhanced motility phenotype is in turn selected during rhizosphere colonization. Several of these highly motile variants were more competitive than the wild-type strain, displacing it from the root tip within 2 weeks.

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Choi, Hyun Soo, e Dong Seok Rhee. "Catalytic Ozonation with Activated Carbon for Treatment of Humic Substances in Water". Applied Mechanics and Materials 470 (dezembro de 2013): 19–22. http://dx.doi.org/10.4028/www.scientific.net/amm.470.19.

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Ozonation of the ubiquitous and poorly biodegradable humic acid in aquatic system was conducted in the presence of activated carbon with the aim of catalyst. The optimum operating parameters deduced from this study was GAC amount of 16.5 v/v% (GAC column volume per reactor volume) in the humic acid solution of initial pH 9. DOC removal rate in Ozone/GAC process was higher than the sum of Ozone alone and GAC adsorption process. Formaldehyde formation in Ozone/GAC process was less than in Ozone alone and GAC adsorption process. The part of molecular size distribution under 10 k Dalton were increased in the Ozone/GAC process.

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Son, Heejong, Sangki Choi, Byungryul An, Hyejin Lee e Hoon-Sik Yoom. "Effect of Changes in Physical Properties of Granular Activated Carbon (GAC) on the Adsorption of Natural Organic Matter (NOM) with Increasing the Number of Thermal Regeneration: Pore Size and NOM Molecular Weight". Journal of Korean Society of Environmental Engineers 43, n.º 7 (31 de julho de 2021): 537–46. http://dx.doi.org/10.4491/ksee.2021.43.7.537.

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Objectives : The purpose of this study was to evaluate the effect of increasing the number of regeneration of granular activated carbon (GAC) on the adsorption capacity of natural organic matter (NOM), and to suggest the technical process options associated the limit number of regeneration and the efficient use of regenerated GAC.Methods : The physicochemical properties of virgin and thermally regenerated GAC were analyzed. To evaluate the NOM adsorption capacity of virgin- and regenerated-GAC, five laboratory-scale columns packed with virgin- and regenerated-GAC were used for treating effluent from pilot-scale drinking water treatment facility. The NOM concentration in the influent and the effluent treated by each column was analyzed by LC-OCD (liquid chromatography-organic carbon detector) to evaluate the adsorption capacity of each NOM fractions (humic substances (HS), building blocks (BB), low molecular weight organics (LMWs)).Results and Discussion : Due to the change in the pore structure of GAC by thermal regeneration, the volume of micropores (< 2 nm) decreased, while the volume of mesopores (> 2 nm) increased. The volume ratio of micropore in virgin-GAC was about 60%, but it gradually decreased as the number of regenerations increased, resulting that the volume ratio of micropore in the 5th-regenerated (5th-Re) GAC decreased to 23%. On the other hand, the volume ratio of mesopore increased in proportion to the number of regenerations from 40% of the virgin GAC to 77% of the 5th-Re-GAC. The DOC adsorption capacities of the regenerated GACs were higher than that of virgin GAC, and the DOC adsorption capacity increased as the number of regenerations increased. As a result of comparing the adsorption capacity of virgin- and regenerated-GAC by NOM fractions, the adsorption capacity of high molecular weight NOM, such as HS, increased by 1.5 to 1.7 times as the number of regenerations increased. In contrast, the adsorption capacity of low molecular weight NOM, such as BB and LMWs, decreased by 78% and 48% as the number of regeneration increased. The limit number of regeneration was evaluated based on that the adsorption capacity (qe) of each NOM fractions keep over than 70% relative to its virgin GAC. As a result, the adsorption capacity for low molecular weight NOM was greatly reduced in GAC regenerated over than 3rd time, so that the 2nd-Re-GAC was valid to keep 70% removal of whole NOM fractions. Low adsorption of low molecular weight NOM (BB and LMWs) by 3rd-Re-GAC could be complemented by using together with virgin-GAC, and low adsorption of high molecular NOMs (HS) could be compensated as well.Conclusions : Due to the change in the pore structure of GAC by thermal regeneration, the DOC adsorption capacity was higher in regenerated GAC than its virgin-GAC, and the adsorption capacity of DOC and high molecular weight NOM (HS) was enhanced as the number of regenerations increased. On the other hand, the pore volume of micropore was reduced by regenerations, and in more than 3rd times regenerations, the adsorption capacity of low molecular weight NOMs (BB and LMWs) was reduced by less than 70% compared to its virgin GAC, so that 2nd-Re-GAC was suggested for suitable GAC. When using a mixture of virgin- and 3rd-Re-GAC, low adsorption of low molecular weight NOM (BB and LMWs) by 3rd-Re-GAC could be complemented by using together with virgin-GAC, and low adsorption of high molecular NOMs (HS) could be compensated as well.

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Orlandini, Ervin, Tsegaye G. Gebereselassie, Joop C. Kruithof e Jan C. Schippers. "Effect of ozonation on preloading of background organic matter in granular activated carbon filters". Water Science and Technology 35, n.º 7 (1 de abril de 1997): 295–302. http://dx.doi.org/10.2166/wst.1997.0289.

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Background Organic Matter (BOM) preloading is adsorption of BOM onto Granular Activated Carbon (GAC) prior to the adsorption of target compounds, such as pesticides and other organic micropollutants (e.g. atrazine). BOM preloading is commonly found to speed up the breakthrough of target compounds during GAC filtration. Ozonation of GAC filter influent may be expected to lower BOM preloading, because it results in less adsorbable and more biodegradable BOM compounds. Short Fixed Bed (SFB) tests with virgin and preloaded GAC, performed within this study, confirmed that preloading of BOM present in pretreated river Rhine water speeds up the breakthrough of atrazine in GAC filters. BOM preloading was found to lower equilibrium adsorption capacity of GAC for atrazine, and to slow down both external and internal mass transfer rate of atrazine on/into GAC. Adsorption capacity of (crushed) GAC was determined from atrazine adsorption isotherms, while mass transfer rate coefficients were determined by fitting the Homogeneous Surface Diffusion model to the breakthrough of atrazine in the SFB tests. More pronounced BOM preloading was found in the GAC filter receiving non-ozonated influent than in its ozonated counterpart. Biodegradation of ozonated BOM was shown to lower BOM preloading in GAC filters.

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THE HO, VIET, HUU TRIET LE e THANH AN NGUYEN. "Genetic characterization of Gac (Momordica cochinchinesis) accessions in Southern Vietnam by ISSR markers". Biodiversitas Journal of Biological Diversity 20, n.º 2 (21 de janeiro de 2019): 387–92. http://dx.doi.org/10.13057/biodiv/d200212.

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Ho VT, Le HT, Nguyen TA. 2019. Genetic characterization of Gac (Momordica cochinchinesis) accessions in Southern Vietnam by ISSR markers. Biodiversitas 20: 387-392. Gac (Momordica cochinchinesis) plays important roles in Vietnamese cuisine and medicine. It has high nutrient and medicinal values. Demand of gac fruit as ingredient for food processing and raw material for health industry requires accelerated gac cultivation. However, gac quality is variable due to the uncertain available germplasm and its management as breeding stock. Identification of gac cultivars and landraces in Vietnam is mainly based on personal experience relying on morphological traits, thus the conservation and breeding have low impact on productivity and quality of product. Recently, the development of molecular markers has been useful in identifying specific plant(s). In this study, genetic richness and relativeness of 14 gac accessions collected from different provinces in Southern Vietnam were evaluated by using 10 Inter-Simple Sequence Repeats (ISSR) markers. Results revealed large variation in genetic background of studied gac accessions. Seven DNA-based markers with potential to differentiate gac genotypes were recorded. The results provide molecular biological information for classification, identification plant origins, breeding and conserving programs of gac in Vietnam.

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Burlingame, G. A., I. H. Suffet e W. O. Pipes. "Predominant bacterial genera in granular activated carbon water treatment systems". Canadian Journal of Microbiology 32, n.º 3 (1 de março de 1986): 226–30. http://dx.doi.org/10.1139/m86-045.

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Granular activated carbon (GAC) beds may be used for removal of dissolved organic matter during the treatment of drinking water. However, they might also change the microbiological quality of the water entering the distribution system either by changing the predominant bacteria or the bacterial density of the treated water. A 3-year pilot plant study of water treatment using GAC beds was conducted at the Baxter Water Treatment Plant in Philadelphia. During the study, bacteria were isolated from the raw water and from the effluents of the GAC treatment units. At the end of the study, bacteria were also isolated from the GAC units and from sand beds operated in parallel with the GAC units. Bacterial genera in the GAC effluents and in the GAC units themselves were similar to those found in the raw water and in the sand beds. Prechlorination and (or) preozonation of the water before GAC treatment had no noticeable effect on the bacterial genera found as compared with GAC unit having no predisinfection. The bacterial genera found in this study were similar to those found in seven other studies of GAC water treatment that used a variety of treatment schemes and a variety of heterotrophic plate count techniques to evaluate bacterial populations. From these several studies it appears that GAC treatment does not change the nature of the bacterial populations associated with drinking water.

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Bastami, Sina, Sina Ghassa, Amin Seyedhakimi e Saeed Chehreh Chelgani. "Adsorption of Mercury from a Cyanide Leaching Solution Using Various Activation Rates of Granular Activated Carbon: A Laboratory- and Industrial-Scale Study". Sustainability 12, n.º 8 (17 de abril de 2020): 3287. http://dx.doi.org/10.3390/su12083287.

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The use of granular activated carbon (GAC) is a typical and sustainable technique for recovering precious metals from a cyanide leaching solution (CLS). The level of GAC activity is a fundamental factor in assessing the rate of precious metal adsorption; thus, it is essential to determine the efficiency of carbon elution for reproducing GACs. Since mercury (Hg) adsorption plays a critical role, economically and environmentally, in GAC efficiency, we conducted various laboratory and industrial experiments to explore the effect of different rates of GAC activation (10%, 35%, 70% and 100%) on Hg adsorption from CLS. Assessments of laboratory test results showed a direct relationship between the Hg adsorption and GAC activity; by increasing the GAC activity from 10% to 100%, the recovery of Hg was increased from 20% to 41%. Kinetic modeling results indicated that the Hg adsorption for all GAC activities followed chemisorption mechanisms. There was good agreement between the laboratory test results and the results of experiments on the industrial scale (that used a continuous circuit). These outcomes indicate that by increasing the frequency of carbon reactivation and using GAC with a high level of activity in the first tank, Hg desorption was meaningfully decreased and recovery was improved (for 10% GAC activity vs. 35% GAC activity, recovery was 40% vs. 90%, respectively).

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Palmieri, Elena, Zoltán Kis, James Ozanne, Roberta Di Benedetto, Beatrice Ricchetti, Luisa Massai, Martina Carducci et al. "GMMA as an Alternative Carrier for a Glycoconjugate Vaccine against Group A Streptococcus". Vaccines 10, n.º 7 (28 de junho de 2022): 1034. http://dx.doi.org/10.3390/vaccines10071034.

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Group A Streptococcus (GAS) causes about 500,000 annual deaths globally, and no vaccines are currently available. The Group A Carbohydrate (GAC), conserved across all GAS serotypes, conjugated to an appropriate carrier protein, represents a promising vaccine candidate. Here, we explored the possibility to use Generalized Modules for Membrane Antigens (GMMA) as an alternative carrier system for GAC, exploiting their intrinsic adjuvant properties. Immunogenicity of GAC-GMMA conjugate was evaluated in different animal species in comparison to GAC-CRM197; and the two conjugates were also compared from a techno-economic point of view. GMMA proved to be a good alternative carrier for GAC, resulting in a higher immune response compared to CRM197 in different mice strains, as verified by ELISA and FACS analyses. Differently from CRM197, GMMA induced significant levels of anti-GAC IgG titers in mice also in the absence of Alhydrogel. In rabbits, a difference in the immune response could not be appreciated; however, antibodies from GAC-GMMA-immunized animals showed higher affinity toward purified GAC antigen compared to those elicited by GAC-CRM197. In addition, the GAC-GMMA production process proved to be more cost-effective, making this conjugate particularly attractive for low- and middle-income countries, where this pathogen has a huge burden.

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Wang, Feifei, Lu Zhang, Liangfu Wei e Jan Peter van der Hoek. "Removal of Hydrogen Peroxide Residuals and By-Product Bromate from Advanced Oxidation Processes by Granular Activated Carbon". Water 13, n.º 18 (7 de setembro de 2021): 2460. http://dx.doi.org/10.3390/w13182460.

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During drinking water treatment, advanced oxidation process (AOP) with O3 and H2O2 may result in by-products, residual H2O2 and BrO3−. The water containing H2O2 and BrO3− often flows into subsequent granular activated carbon (GAC) filters. A concentrated H2O2 solution can be used as GAC modification reagent at 60 °C to improve its adsorption ability. However, whether low concentrations of H2O2 residuals from AOP can modify GAC, and the impact of H2O2 residuals on BrO3− removal by the subsequent GAC filter at ambient temperature, is unknown. This study evaluated the modification of GAC surface functional groups by residual H2O2 and its effect on BrO3− removal by GAC. Results showed that both H2O2 and BrO3− were effectively removed by virgin GAC, while pre-loaded and regenerated GACs removed H2O2 but not BrO3− anymore. At the ambient temperature 150 µmol/L H2O2 residuals consumed large amounts of functional groups, which resulted in the decrease of BrO3− removal by virgin GAC in the presence of H2O2 residuals. Redox reactions between BrO3− and surface functional groups played a dominant role in BrO3− removal by GAC, and only a small amount of BrO3− was removed by GAC adsorption. The higher the pH, the less BrO3− removal and the more H2O2 removal was observed.

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Obayomi, Kehinde Shola, Sie Yon Lau, Zongli Xie, Stephen R. Gray e Jianhua Zhang. "In-Situ Hydrothermal Fabrication of ZnO-Loaded GAC Nanocomposite for Efficient Rhodamine B Dye Removal via Synergistic Photocatalytic and Adsorptive Performance". Nanomaterials 14, n.º 14 (22 de julho de 2024): 1234. http://dx.doi.org/10.3390/nano14141234.

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In this work, zinc oxide (ZnO)/granular activated carbon (GAC) composites at different ZnO concentrations (0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC) were prepared by an in-situ hydrothermal method and demonstrated synergistic photocatalytic degradation and adsorption of rhodamine B (RhB). The thermal stability, morphological structure, elemental composition, crystallographic structure, and textural properties of developed catalysts were characterized by thermal gravimetric analysis (TGA/DTG), scanning electron microscopy equipped with energy dispersive-x-ray (SEM-EDS), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. The successful loading of ZnO onto GAC was confirmed by SEM-EDS and XRD analysis. The BET surface areas of GAC, 0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC were 474 m2/g, 450 m2/g, 453 m2/g, and 421 m2/g, respectively. The decrease in GAC could be attributed to the successful loading of ZnO on the GAC surface. Notably, 0.5M-ZnO@GAC exhibited the best photocatalytic degradation efficiency of 82% and 97% under UV-A and UV-C light over 120 min, attributed to improved crystallinity and visible light absorption. The photocatalytic degradation parameters revealed that lowering the RhB concentration and raising the catalyst dosage and pH beyond the point of zero charge (PZC) would favor the RhB degradation. Photocatalytic reusability was demonstrated over five cycles. Scavenger tests revealed that the hydroxyl radicals (•OH), superoxide radicals (O2−•), and photoinduced hole (h+) radicals play a major role during the RhB degradation process. Based on the TOC results, the RhB mineralization efficiency of 79.1% was achieved by 0.5M-ZnO@GAC. Additionally, GAC exhibited a strong adsorptive performance towards RhB, with adsorption capacity and the RhB removal of 487.1 mg/g and 99.5% achieved within 90 min of equilibrium time. The adsorption characteristics were best described by pseudo-second-order kinetics, suggesting chemical adsorption. This research offers a new strategy for the development of effective photocatalyst materials with potential for wider wastewater treatment applications.

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Panijel, Mary, Laura Chalupowicz, Guido Sessa, Shulamit Manulis-Sasson e Isaac Barash. "Global Regulatory Networks Control the Hrp Regulon of the Gall-Forming Bacterium Pantoea agglomerans pv. gypsophilae". Molecular Plant-Microbe Interactions® 26, n.º 9 (setembro de 2013): 1031–43. http://dx.doi.org/10.1094/mpmi-04-13-0097-r.

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Gall formation by Pantoea agglomerans pv. gypsophilae is dependent on the hypersensitive response and pathogenicity (hrp) system. Previous studies demonstrated that PagR and PagI, regulators of the quorum-sensing system, induce expression of the hrp regulatory cascade (i.e., hrpXY, hrpS, and hrpL) that activates the HrpL regulon. Here, we isolated the genes of the Gac/Rsm global regulatory pathway (i.e., gacS, gacA, rsmB, and csrD) and of the post-transcriptional regulator rsmA. Our results demonstrate that PagR and PagI also upregulate expression of the Gac/Rsm pathway. PagR acts as a transcriptional activator of each of the hrp regulatory genes and gacA in a N-butanoyl-L-homoserine lactone-dependent manner as shown by gel shift experiments. Mutants of the Gac/Rsm genes or overexpression of rsmA significantly reduced Pantoea agglomerans virulence and colonization of gypsophila. Overexpression of rsmB sRNA abolished gall formation, colonization, and hypersensitive reaction on nonhost plants and prevented transcription of the hrp regulatory cascade, indicating a lack of functional type III secretion system. Expression of rsmB sRNA in the background of the csrD null mutant suggests that CsrD may act as a safeguard for preventing excessive production of rsmB sRNA. Results presented indicate that the hrp regulatory cascade is controlled directly by PagR and indirectly by RsmA, whereas deficiency in RsmA activity is epistatic to PagR induction.

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Vaitovich, Aliaksandra Uladzimirauna. "The role of the Globular Amphora Culture in the development of the Upper Neman communities". Samara Journal of Science 8, n.º 2 (1 de abril de 2019): 106–14. http://dx.doi.org/10.17816/snv201982204.

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The paper discusses the problems of the Globular Amphora Culture (hereinafter the GAC) in the Upper Neman region. According to the proposition of M. Shmyt the sources related to the GAC have been divided in two groups. The first group is made up of the so-called pure sources i.e. the materials directly related to the GAC although hypothetically at times. It includes cemeteries, flint mines and workshops as well as finds of the quadrangular ground flint axes and chisels. The second group comprises so-called syncretic sources associated with the broad understood GAC traditions. The traits genetically linked to the GAC could be identified in materials of the Neman Culture as well as the local groups of the Corded Ware cultures Range. The presence of the GAC people and traditions in the area in question is dated to the second quarter III - first quarter II BC. Two main forms of transfer the GAC traditions have been distinguished. Firstly, the Upper Neman region was the territory of the direct contacts between the GAC people and the local populations. Secondly, the GAC elements had been distributed in the synthesized forms. The major source of the synthesized GAC traits was the Rzucewo Culture as well as the Middle Dnieper Culture. The prospects of the archaeological research are discussed. On the current stage of the research, the issue of the chronology of the GAC traditions spreading in the area in question requires a more detailed study. Top priority should also be given to a thorough investigation of the GAC role in the socio-economic transformation of the Upper Neman population in the III - the beginning II mill. BC.

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