scholarly journals 1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Julieta Cabrera ◽  
Dwight Acosta ◽  
Alcides López ◽  
Roberto J. Candal ◽  
Claudia Marchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Photocatalytic Activity ◽  
Bactericidal Activity ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
E Coli ◽  
1D Nanostructures ◽  
Sol Gel Synthesis ◽  
Hydrolysis Of ◽  
Tio2 Nanostructures

TiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis). The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. The photocatalytic activity of 1D nanostructures was evaluated by measuring the deactivation of E. coli in stirred water in the dark and under UV-A/B irradiation. Results show that in addition to the bactericidal activity of TiO2 under UV-A illumination, under dark conditions, the decrease in bacteria viability is ascribed to mechanical stress due to stirring.

Synthesis, characterization and photocatalytic activity of 1D TiO2 nanostructures

2014 ◽  
Vol 70 (6) ◽  
pp. 972-979 ◽  
Author(s):  
Julieta Cabrera ◽  
Hugo Alarcón ◽  
Alcides López ◽  
Roberto Candal ◽  
Dwight Acosta ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Surface Area ◽  
Sol Gel ◽  
One Dimensional ◽  
Tio2 Anatase ◽  
1D Nanostructures ◽  
Sol Gel Process ◽  
Tio2 Nanopowders ◽  
The One ◽  
Tio2 Nanostructures

Nanowire/nanorod TiO2 structures of approximately 8 nm in diameter and around 1,000 nm long were synthesized by alkaline hydrothermal treatment of two different TiO2 nanopowders. The first precursor was TiO2 obtained by the sol-gel process (SG-TiO2); the second was the well-known commercial TiO2 P-25 (P25-TiO2). Anatase-like 1D TiO2 nanostructures were obtained in both cases. The one-dimensional (1D) nanostructures synthesized from SG-TiO2 powders turned into rod-like nanostructures after annealing at 400 °C for 2 h. Conversely, the nanostructures synthesized from P25-TiO2 preserved the tubular structure after annealing, displaying a higher Brunauer–Emmett–Teller surface area than the first system (279 and 97 m2/g, respectively). Despite the higher surface area shown by the 1D nanostructures, in both cases the photocatalytic activity was lower than for the P25-TiO2 powder. However, the rod-like nanostructures obtained from SG-TiO2 displayed slightly higher efficiency than the sol-gel prepared powders. The lower photocatalytic activity of the nanostructures with respect to P-25 can be associated with the lower crystallinity of 1D TiO2 in both materials.

Scalable Free-Radical Polymerization Based Sol-Gel Synthesis of SrTiO3 and its Photocatalytic Activity

2017 ◽  
Vol 2 (17) ◽  
pp. 4836-4842 ◽  
Author(s):  
Swapna Challagulla ◽  
Ravikiran Nagarjuna ◽  
Sounak Roy ◽  
Ramakrishnan Ganesan
Keyword(s):  
Photocatalytic Activity ◽  
Free Radical ◽  
Radical Polymerization ◽  
Sol Gel ◽  
Free Radical Polymerization ◽  
Sol Gel Synthesis

Effects of Water Source, Dilution, Storage, and Bacterial and Fecal Loads on the Efficacy of Electrolyzed Oxidizing Water for the Control of Escherichia coli O157:H7

2004 ◽  
Vol 67 (7) ◽  
pp. 1377-1383 ◽  
Author(s):  
S. M. L. STEVENSON ◽  
S. R. COOK ◽  
S. J. BACH ◽  
T. A. McALLISTER
Keyword(s):  
Escherichia Coli ◽  
Bactericidal Activity ◽  
Storage Temperature ◽  
Uv Light ◽  
Tap Water ◽  
Organic Matter Content ◽  
Water Source ◽  
Deionized Water ◽  
Escherichia Coli O157 ◽  
E Coli

To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 104 CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P < 0.001) their ORP values to <700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 104 CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24°C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P < 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to ≤848 mV. When stored in the dark, the diluted EO waters retained an ORP of >848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4°C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.

The sol-gel synthesis and photocatalytic activity of Gd-SiO2-TiO2 photocatalyst

2019 ◽  
Vol 733 ◽  
pp. 136676 ◽  
Author(s):  
Hongwei Feng ◽  
Hui Xu ◽  
Hongtu Feng ◽  
Ying Gao ◽  
Xinyuan Jin
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
Tio2 Photocatalyst ◽  
Sol Gel Synthesis

scholarly journals Microwave treated sol–gel synthesis and characterization of hybrid ZnS–RGO composites for efficient photodegradation of dyes

2017 ◽  
Vol 41 (4) ◽  
pp. 1723-1735 ◽  
Author(s):  
Lellala Kashinath ◽  
Keerthiraj Namratha ◽  
Shivanna Srikantaswamy ◽  
Ajayan Vinu ◽  
Kullaiah Byrappa
Keyword(s):  
Electron Transfer ◽  
Photocatalytic Activity ◽  
Sol Gel ◽  
Charge Recombination ◽  
Synthesis And Characterization ◽  
Excellent Photocatalytic Activity ◽  
Sol Gel Synthesis

Excellent photocatalytic activity by highly photo-responsive electron transfer from ZnS–RGO, and RGO acts as an electron reservoir and effectively suppresses charge recombination.

Alteration of the phagocytosis and antimicrobial defense of Octodonta nipae (Coleoptera: Chrysomelidae) pupae to Escherichia coli following parasitism by Tetrastichus brontispae (Hymenoptera: Eulophidae)

2018 ◽  
Vol 109 (2) ◽  
pp. 248-256
Author(s):  
E. Meng ◽  
J. Li ◽  
B. Tang ◽  
Y. Hu ◽  
T. Qiao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Immune Response ◽  
Immune Responses ◽  
Mrna Expression ◽  
Bactericidal Activity ◽  
Bacterial Infections ◽  
Expression Level ◽  
Primary Immune Response ◽  
Mrna Expression Level ◽  
E Coli

AbstractAlthough parasites and microbial pathogens are both detrimental to insects, little information is currently available on the mechanism involved in how parasitized hosts balance their immune responses to defend against microbial infections. We addressed this in the present study by comparing the immune response between unparasitized and parasitized pupae of the chrysomelid beetle, Octodonta nipae (Maulik), to Escherichia coli invasion. In an in vivo survival assay, a markedly reduced number of E. coli colony-forming units per microliter was detected in parasitized pupae at 12 and 24 h post-parasitism, together with decreased phagocytosis and enhanced bactericidal activity at 12 h post-parasitism. The effects that parasitism had on the mRNA expression level of selected antimicrobial peptides (AMPs) of O. nipae pupae showed that nearly all transcripts of AMPs examined were highly upregulated during the early and late parasitism stages except defensin 2B, whose mRNA expression level was downregulated at 24 h post-parasitism. Further elucidation on the main maternal fluids responsible for alteration of the primary immune response against E. coli showed that ovarian fluid increased phagocytosis at 48 h post-injection. These results indicated that the enhanced degradation of E. coli in parasitized pupae resulted mainly from the elevated bactericidal activity without observing the increased transcripts of target AMPs. This study contributes to a better understanding of the mechanisms involved in the immune responses of a parasitized host to bacterial infections.

Inhibition of Escherichia coli O157:H7 in Ripening Dry Fermented Sausage by Ground Yellow Mustard

2008 ◽  
Vol 71 (3) ◽  
pp. 486-493 ◽  
Author(s):  
GARY H. GRAUMANN ◽  
RICHARD A. HOLLEY
Keyword(s):  
Escherichia Coli ◽  
Starter Culture ◽  
Escherichia Coli O157 ◽  
Fermented Sausage ◽  
Yellow Mustard ◽  
E Coli ◽  
Dry Fermented Sausage ◽  
Hydrolysis Of ◽  
Antimicrobial Effectiveness ◽  
Dry Sausage

Compounds generated by the enzymatic hydrolysis of glucosinolates naturally present in mustard powder are potently bactericidal against Escherichia coli O157:H7. Because E. coli O157:H7 can survive the dry fermented sausage manufacturing process, 2, 4, and 6% (wt/wt) nondeheated (hot) mustard powder or 6% (wt/wt) deheated (cold) mustard powder were added to dry sausage batter inoculated with E. coli O157:H7 at about 7 log CFU/g to evaluate the antimicrobial effectiveness of the powders. Reductions in E. coli O157:H7 populations, changes in pH and water activity (aw), effects on starter culture (Pediococcus pentosaceus and Staphylococcus carnosus) populations, and effects of mustard powder on sausage texture (shear) were monitored during ripening. Nondeheated mustard powder at 2, 4, and 6% in dry sausage (0.90 aw) resulted in significant reductions in E. coli O157:H7 (P < 0.05) of 3.4, 4.4, and 6.9 log CFU/g, respectively, within 30 days of drying. During fermentation and drying, mustard powder did not affect P. pentosaceus and S. carnosus activity in any of the treatments. Extension of drying to 36 and 48 days reduced E. coli O157:H7 by >5 log CFU/g in the 4 and 2% mustard powder treatments, respectively. The 6% deheated mustard powder treatment provided the most rapid reductions of E. coli O157:H7 (yielding <0.20 log CFU/g after 24 days) by an unknown mechanism and was the least detrimental (P < 0.05) to sausage texture.

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