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76 Cards in this Set
- Front
- Back
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Where are silver NPs |
electronics, paints, sunscreens |
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Function of silver NPs |
Disinfection of air, water, surface |
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silver NPs mechanisms |
Adhesion to cell membranes, penetrates cell to damage DNA, release of Ag+ ion |
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Synthesis of Ag NPs (2 routes) |
Physical: evaporation/condensation, laser ablation Chemical: chemical reduction |
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Evaporation-condensation technique Laser ablation |
Tube furnace at atmospheric pressure, ceramic heater Pure colloids |
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chemical reduction |
most frequently applied, ag+ions-->silver atoms-->colloidal Ag particles |
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Green synthesis of Ag NPs |
Selection of solvent medium, environmentally benign reducing agent, selection of nontoxic substances for Ag NPs stability Aqueous stem extract, antidiabetic/antioxidant activity, inhibit free radicals |
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Antibacterial mechanisms |
Disrupts membrane permeability and inhibits DNA replication |
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Toxicity? |
To organisms and the ecosystem |
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Biosensors applications silver NPs |
Surface enhanced raman spectroscopy |
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silver NPs water treatment application |
Coat, foams by overnight exposure, antibacterial |
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silver NPs paints (antibacterial application) |
eco-friendly raw materials, no extra purification process |
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Advantages of silver NPs |
Low toxicity to humans, antibacterial, prevents coagulation of paint, biocide, scratch-free film |
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silver NPs future |
Photocatalyst, pathogen detection (surface coatings) reactivity, anti-fouling (membranes) |
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Carbon nanotubes synthesis |
cylindrical graphite sheets rolled up into tube-like structure, single-walled/multi-walled |
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Carbon nanotubes beneficial properties |
low energy consumption, thermal stability, anti-fouling/antibacterial, self cleaning |
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Carbon nanotubes surfactant design leads to... |
Adsorption of heavy metals |
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Carbon nanotubes use in desalination membranes |
removes unwanted compounds, can be vertically aligned (large water flux) or mixed matrix (easily produced, cost reduction) |
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Carbon nanotubes beneficial properties for water filtration/desalination |
Provides near frictionless water flow with high retention, highly efficient transport of water molecules, insoluble |
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Carbon nanotubes toxicology |
enter body, manifest as inflammation/oxidative stress |
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Carbon nanotubes environmental significance |
substantial production volumes, non-biodegradable, transport pollutants |
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Carbon nanotubes fabrication |
Arc-discharge (current, anode, inert gas in vacuum) Laser ablation |
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Carbon nanotubes, why gas sensors? |
Tunable electrical properties, highly sensitive, used in extreme environments, low power consumption |
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Carbon nanotubes chemiresistor ChemFET |
Measures changes in resistance, limited working temp Measures carrier current, Higher sensitivity, more expensive |
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Carbon nanotubes sensing through... |
improved sensitivity and selectivity |
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Carbon nanotubes toxic properties similar to... |
Asbestos Antibacterial via cell membrane damage |
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Carbon nanotubes general... |
Better electrical properties, improved sensitivity, can be functionalized to detect numerous gas species, decreasing CNT production costs |
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Problems with current desal techniques |
Membrane fouling |
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Graphene structure |
Thinnest compound, can be single/few layered, nano sheets, ribbons |
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Graphene features
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Very strong and durable, transparent/flexible, electrical/mechanical/optical properties |
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Graphene synthesis |
Chemical exfoliation of graphite, unzipping CNT to form graphene ribbons |
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Graphene desal: Capacitive deionization |
Based on electrosorption, lower operating costs and energy consumption |
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Graphene desal: nanocomposite membranes |
Thin film, fabricated via layer-by layer deposition of cross linked GO nanosheets |
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Graphene desal: free-standing grapheme membranes |
selective permeability, hydroxylated pores |
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Graphene desal advantages |
Faster water flow, low pressure requirements, higher pure water permeability lower salt rejection rates than CNTs |
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Graphene health concerns |
ROS generation, cytotoxic, membrane toxic, respiratory |
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Graphene sponge is... |
Polyurethane sponges coated with reduced graphene oxide particles |
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Why graphene oxide? How to make it? |
Compound with low-cost, chemical stability, and environmentally friendly Comes from graphite, reduce it to make it hydrophobic |
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3 ways to create graphene oxide foams
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Unidirectional freezing drying, non-directional freezing drying, air freezing drying ( Use liquid nitrogen in all 3 for freezing agent, vary the amount of time exposed to it and container the rGO is stored in |
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Foams successful with what 2 tests? |
Drop method: organic liquid dropped on foam until no more absorbed Soaked method: foam place in water and allowed to soak up oil |
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Environmental impacts of Graphene |
reusability goal to be practical, easy to clean and recycle, used up to ten cycles |
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How to recycle Graphene sponge |
Just apply heat, or direct combustion |
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Skimmers Natural adsorbents |
Mechanical devices designed to recover oil from the water's surface, oil attracting surfaces Low oil loading and adsorption, can cause other types of pollution |
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In situ burning of oil |
Burn by-products into the air, but reduces volume/need for collection and storage |
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Advantage of graphene to conventional methods |
Higher adsorption ability, highly selective, reusable BUT toxicological risks of inhalation or absorption |
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MgO properties |
Polyhedral with a cubic internal structure, porous, adsorbent |
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MgO synthesis |
Aerogel, precipitation, reflux, hydrothermal Creates nano rods or nanoflakes |
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MgO sorbs pollutants (dyes in rivers), has the highest rate of... |
Adsorption, dye molecules embed into porous structure |
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MgO may mitigate... Adsorbs... |
Eutrophication phosphate and nitrate |
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MgO removes what metal in water Also de-(somethings) water |
Copper, defluoridate |
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MgO in air adsorption called... What is AP-MgO |
Chemisorption Aerogel-prepared (adsorbs more) |
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MgO is toxic to... |
microbes and humans |
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MgO environmental applications |
Water remediation (removal of dyes, copper, fluorine, and organic pollutants via sorption) Air remediation (removal of SO2, CO2, VOCs via adsorption) |
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Commonalities between UFPs and NPs Differences |
Surface area/volume Exposure route of inhalation Uniformity Source Organic chemical content Adverse health effects (though probably same) |
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Modes of NP delivery in human |
Ingestion, respiration, dermal contact |
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2 processes that remove nano particles in respiratory tract |
Chemical clearance: chemical dissolution mediated by respiratory tract components Physical translocation: movement of an intact particle, location dependent |
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Properties that make nano materials potentially toxic |
Redox cycling, photo activation, membrane damage, cytotoxicity, inflammation, ROS |
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Primary cellular responses to NPs |
Antioxidative response! Pro-inflammatory response Lysosome permeation Decrease in mitochondrial membrane potential Ca2+ release Capase activation Cell apoptosis |
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ROS are continually generated where? At low concentrations they are... |
In the mitochondrion Easily neutralized |
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3 tiers of oxidative stress |
Tier 1: Anti-oxidant defense (induction of antioxidant and detoxification enzymes) 2: inflammation (initiated through the activation of pro-inflammatory signaling cascades) 3: cytotoxicity (programmed cell death results from perturbation of the mitochondrion) |
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What is oxidative stress? |
Too much ROS Antioxidants lead to ROS lacking |
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3 immune responses when nano materials are recognized |
Antigenicity (response of an antibody to an antigen) Adjuvant properties (Agents added to augment the immune response to a vaccine) Inflammatory response (immune system cells activated, cytokines secreted) |
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Cytokines Opsonins |
Signaling molecules whose presence leads to the attraction of additional cells to destroy the foreign substance Blood serum proteins that signal cells to ingest a foreign material |
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Importance of opsonization |
binding of blood proteins to carbon nanotubes reduces cytotoxicity |
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Environmental impacts of NPs in general |
Disposal/accidental discharge can affect microbial ecology and disrupt biogeochemical cycles Antimicrobial activity indicative of toxicity to higher level organisms |
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How do NPs move through soils? Water? Air? |
Pores maybe? Bio-uptake/degradation/aggregation/sorption Aerosolization |
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What is risk? |
Hazard*exposure Shark cage: hazard but no exposure Sand shark at aquarium: exposure but no hazard Great white and a surfer: hazard and exposure |
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Bacterial toxicity mechanisms |
Release of toxic ions, protein oxidation, disruption of membrane/cell wall, ROS, DNA damage |
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nC60 |
Highly stable water suspension, negatively charged surface, antibacterial Doesn't puncture cells |
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Fullerenes does respose |
More branches are less toxic, but more mobile |
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nC60 particle size vs toxicity |
100x difference in antibacterialness for greater than and less than 100nm particles BUT only a 2x difference in surface area:volume |
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What reduces nC60 toxicity? |
NOM |
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Quantum dots applications Weathering |
Biomedical and electronics Toxicity is due to free metal, so weathering increases their toxicity to cells Coated QDs retard cell growth, weathered QDs kill bacteria |
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Salinity increases... Organic ligands mitigate... |
QD aggregation Toxicity |
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Copper nanoparticles |
Cheaper antimicrobial than Ag Sustainable applications in solar panels and groundwater remediation Aquatic anti-fouling and anti-algal coating |
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Copper NP energy/environmental relevance |
Carbon sequestration Biofuel production Eutrophication |
