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At.European.level,.the.manufacturing.industry.is.facing.today.a.growing.pressure.derived.from.competitive.economies..Especially.in.the.high-technology.area,.there.are.already.developed.economies,.such.as.China,.which.are.threatening.Europe’s.primacy1..To.date,.manufacturing.sector.consists.of.the.1/4.of.the.EU’s.gross.domestic.product.(GDP),.while.it.offers.millions.of.jobs,.in.times.that.unemployment.is.consistently.growing..Despite.the.uprising.economies,.the.EC.industrial.sector.is.dominating.in.international.level,.consisting.of.the.flagship.in.areas.such.as.automotive,.and.machinery.

In.order.for.Europe.to.maintain.this.status,.a.new.strategy.needs.to.be.implemented.from.cost-based.competition.to.a.new.approach.based.on.the.creation.of.high.added.value.products..Such.a.strategy.should.aim.in.more.environmental-friendly.and.high.quality.products..Additionally,.new.production.methods.have.to.be.developed.in.order.to.combine.greater.production.volumes.with.less.energy.and.material.consumption..Better.synthetic.methods.to.build.and.control.particle.morphology,.in.large-scale.manufacturing,.will.be.needed.to.broadly.allow.the.penetration.of.nanomaterials.(NMs).into.industrial.sector.

One.of.the.most.promising.fields.in.the.manufacturing.section.is.NMs.manufacturing..”Nanomanufacturing”.is.now.a.growing.economy2..There.are.estimations.that.NMs’.sales.will.reach.the.14.billion.Euros.by.2015,.while.reliable.estimations.cannot.be.conducted.beyond.2020..However,.while.NMs.enter.early.in.the.value.chain,.they.are.often.not.visible.in.the.final.product..Thus,.nanotechnology.should.be.considered.as.a.developing.scientific.field.for.the.most.of.the.industrial.sectors.with.uncalculated.profits.by.the.end.of.this.decade..Taking.that.into.account,.it.is.oxymoron.the.fact.that.nowadays.there.are.relatively.few.companies.in.Europe.working.exclusively.on.NMs.manufacturing..At.a.European.level,.nanomaterials’.manufacturing.does.not.reflect.the.global.emphasis.on.carbon-based.nanomaterials,.such.as.fullerenes,.carbon.nanotubes.(CNTs).and.carbon.nanofibres.(CNFs)..Most.of.the.manufacturers.that.use.nanomaterials.in.their.production.line.do.not.use.them.in.significant.quantities.

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The.scientific.community.turned.their.research.efforts.in.the.development.of.novel.production.methods.of.NMs.in.order.to.make.their.production.more.attractive.to.the.industrial.sector..Most.of.today’s.products.involving.fabricated.nanostructures.are.produced.using.top.down.conventional.technologies,.while.the.large.facilities,.needed.for.large-scale.production,.have.a.huge.environmental.impact.3

Unfortunately,.most.of.the.suggested.methods.fail.either.to.apply.to.a.large.scale.production,.or.in.succeeding.in.preserving.the.produced.NMs,.with.the.desired.properties..Another.major.issue.that.scientists.deal.with.is.the.fact.that.these.novel.manufacturing.processes.should.address.to.be.equipped.with.in.situ.monitoring.of.the.whole.process.in.order.to.deliver.high.quality.products..One.possible.solution.is.the.online.monitoring.of.the.whole.process.which.allows.a.constant.feedback.from.the.product.quality,.thus.minimizing.the.chances.of.a.product.failure..Hence,.it.is.critical.for.the.scientific.community.as.well.as.for.the.end-users,.a.strong.cooperation.to.be.developed.in.order.these.obstacles.to.be.overcome.

In.this.sense,.European.Commission4has.developed.private-public.partnerships.in.order.to.support.research.in.the.field.of.NMs.manufacturing..In.the.frame.of.FP6.and.FP7.projects,.EC.had.invested.€240.000.000,.while.in.the.frame.of.HORIZON.2020,.over.1.billion.Euros.will.be.invested.from.both.the.European.Commission.and.manufacturing.industries.in.order.to.develop.and.promote.key.enabling.technologies..This.investment.will.aid.the.European.manufacturing.industry.and.especially.small.and.medium.enterprises,.to.successfully.correspond.in.this.new.competitive.environment,.through.the.development.of.novel.manufacturing.methods.

These.newly.developed.NMs.manufacturing.methods,.although.still.in.research.labs,.are.expected.to.provide.with.nanoparticles.and.nanostructures.of.high.process.throughput.and.low.product.costs..Rough.estimations.show.that.over.100.kg/day.of.products,.ten.times.higher.than.today’s.volumes,.will.be.synthesized.by.using.innovative.production.methods..It.is.clear.that.such.methods.will.dramatically.decrease.current.nanomanufacturing.obstacles,.and.lead.in.the.creation.of.entirely.new.applications

Nanoscale.materials.are.defined.as.a.set.of.substances.where.at.least.one.dimension.is.less.than.approximately.100.nanometers.

A.nanometer.is.one.millionth.of.a.millimeter.–.approximately.100000.times.smaller.the.diameter.of.human.hair.

1.1.1.  WET.CHEMICAL.SYNTHESIS.OF.NANOMATERIALS:

In.principle.we.can.classify.the.wet.chemical.synthesis.of.nanomaterials.into.two.broad.groups:

1.    
The.top.down.method:.where.single.crystals.are.etched.in.an.aqueous.solution.for.producing.nanomaterials,.For.example,.the.synthesis.of.porous.silicon.by.electrochemical.etching.

2.    
The.bottom.up.method:.consisting.of.sol-gel.method,.precipitation.etc..where.materials.containing.the.desired.precursors.are.mixed.in.a.controlled.fashion.to.forma.colloidal.solution.

 

 

 

 

 

2..Methods.for.large-scale.synthesis.of.nanomaterials

2.1..Bottom-up.approaches

2.1.1..Vapour.phase.techniques

2.1.1.1..Aerosol.based.processes

A.common.method.for.industrial.production.of.nanoparticles.is.the.aerosol.based.processes5,.6..An.aerosol.can.be.defined.as.a.system.of.solid.or.liquid.particles.suspended.in.air.or.other.gaseous.environment..Particles.can.range.from.molecules.up.to.100.?m.in.size..The.use.of.aerosols.was.known.many.years.before.the.basic.science.and.engineering.of.them.were.understood..For.example,.pigments.as.carbon.black.particles.and.titania.were.used.as.reinforcements.for.car.tires.and.for.the.production.of.paints.and.plastics,.respectively..Another.example.is.fumed.silica.and.titania.formed.from.respective.tetra.chlorides.by.flame.pyrolysis..Also,.optical.fibres.are.manufactured.by.similar.process.7

Spraying.is.used.either.for.drying.wet.materials.or.for.applying.coatings..When.the.precursor.chemicals.are.sprayed.onto.a.heated.surface.or.into.hot.atmosphere,.a.precursor.pyrolysis.occurs.and.particles.are.formatted..An.electro-spraying.process.in.room.temperature.was.developed.at.Oxford.University.for.the.production.of.semiconductors.and.metal.nanoparticles8..Spray.gun.deposition.technique.was.also.applied.for.the.deposition.of.catalysts.precursors,.such.as.iron.chlorides.(III),.in.order.to.achieve.the.growth.of.CNTs..Such.methods.of.catalysts’.deposition.as.film.on.various.substrates.are.simple,.cost.effective.and.can.be.applied.on.large.surfaces9

2.1.1.2..Arc.discharge.generation

Another.means.of.vaporizing.metals.is.the.utilization.of.an.electric.arc.as.a.source.of.energy..This.technique.is.based.on.charging.two.electrodes.made.of.the.metal.to.be.vaporized.in.the.presence.of.an.inert.gas..A.large.current.is.applied.until.the.breakdown.voltage.is.reached..The.arc.created.across.the.two.electrodes.leads.to.the.vaporization.of.a.small.amount.of.metal.of.one.electrode.to.another..This.method.produces.very.small.amounts.of.metal.nanoparticles,.but.is.characterized.by.relative.reproducibility..Metal-oxides.or.other.compounds.can.be.produced.by.using.oxygen.or.another.reactive.gas10..Even.though.the.arc.discharge.is.a.well-known.method,.the.process.control.of.the.arc’s.extremely.high.temperature.leading.to.high.evaporation.rates.is.of.significant.importance.for.industrial.processing..Moreover,.high.concentrations.of.the.vaporized.metal.in.the.carrier.gas.may.produce.large.particles.11

A.European.project.named.BUONAPART-E.(Better.Upscaling.and.Optimization.of.Nanoparticle.and.Nanostructure.Production.by.Means.of.Electrical.Discharges).12.is.currently.running.and.aims.at.the.development.of.an.optimized.single.unit.(OSU),.which.is.depicted.in.Figure.1..The.latter.is.the.basic.evaporation.unit,.for.large.scale.production.of.metal.nanoparticles.by.using.electrical.discharge.methods..The.process.is.simple,.versatile.and.reliable.and.the.production.rate.ranges.between.0.1.and.10.g/h,.an.increase.by.a.factor.of.10.to.100.beyond.the.current.state-of-the-art.for.the.single.unit..The.basic.unit.is.a.pair.of.electrodes.and.a.large.number.of.these.pairs.can.be.placed.in.a.single.housing,.resulting.in.the.demonstration.of.multiple.units.of.the.OSU.in.parallel,.in.a.closed-loop.carrier.gas.recycling.system,.in.a.production.facility.yielding.1.kg/day..The.challenge.of.this.project.is.to.show.that.the.product.quality.from.multiple.parallel.OSUs.and.a.single.unit.are.identical..The.size.of.the.primary.particles.is.controlled.by.the.carrier.gas.composition.and.the.applied.electric.current..Nitrogen.is.the.most.economic.carrier.gas,.leaving.electric.current.as.the.only.process.parameter..A.higher.electric.current.results.in.the.production.of.bigger.particles.and.thereby.to.an.increased.production.rate..The.parallelization.of.many.electrode.pairs.can.optimize.both.production.rate.and.particle.size.<100.nm..Current.results.of.the.project.include.that.the.production.rate.of.about.0.6.kg/day.of.the.multiple.OSU.containing.8.OSUs.is.approximately.8.times.the.production.rate.of.the.OSU;.and.the.specific.electricity.consumption.is.in.the.same.range.for.the.multiple.OSU.as.it.is.for.the.OSU..To.conclude,.this.is.a.very.important.result.as.it.proves.that.the.scaling-up.by.multiplying.the.number.of.OSU.in.one.housing.is.working.for.large.scale.production.of.metal.nanoparticles13,.14 2.1.2.2..Sonochemical.method Sonochemistry.is.the.research.area.in.which.molecules.undergo.chemical.reaction.due.to.the.application.of.powerful.ultrasound.radiation..The.driving.force.responsible.for.the.sonochemical.process.is.acoustic.cavitation,.which.includes.the.formation,.growth.and.collapse.of.bubbles.in.an.ultrasonically.irradiated.liquid..Even.though,.cavitation.is.considered.to.be.avoided.in.the.construction.of.reactors.(erosion.damage),.acoustic.cavitation.is.the.key.to.sonochemical.processing.due.to.its.ability.to.control.and.limit.its.effects.to.the.reaction.and.not.the.reactor..This.method.has.been.extensively.used.to.produce.nanosized.materials.with.unusual.properties,.since.the.unique.conditions.(very.high.temperatures.(5000.K),.pressures.(>20.MPa).and.cooling.rates.(>109.K.s?1)).facilitate.the.formation.of.smaller.particles.and.different.shapes.of.products.compared.to.other.methods..The.main.advantage.in.conducting.sonochemical.experiments.is.that.it.is.very.inexpensive.

 

2.2..Top-down.approaches

2.2.1..Solid.phase.techniques

2.2.1.1..Mechanical.attrition.(milling/mechanochemical.processing)

Mechanical.attrition.(MA).is.a.method.that.has.been.developed.since.1970,.as.an.industrial.process.for.producing.new.alloys.and.phase.mixtures.from.powder.particles..This.method.can.overcome.the.quantity.limitations.for.nanocrystalline.preparation,.so.nanocrystalline.powders.can.be.produced.in.large.scale..Moreover,.it.offers.many.perspectives.in.preparing.a.different.number.of.structures.in.nanostructured.powders,.like.crystalline/crystalline.or.crystalline/amorphous.and.atomic.bonding.like.metal/metal,.metal/semiconductor,.metal/ceramic,.etc..An.important.advantage.is.that.mechanical.milling.process.can.work.at.low.temperatures,.so.the.newly.formed.grains.can.grow.very.slowly17..By.this.method.it.is.possible.to.prepare.advanced.materials.with.particular.grain.or.interface-boundary.design..Because.in.many.cases.it.is.difficult.to.distinguish.a.glassy.structure.by.a.nano-crystalline.structure,.research.is.oriented.to.nanocrystalline.nanomaterials,.in.which.grain.or.interphase.boundaries.between.the.nanophase.domains.exist.18

Two.different.techniques.have.been.developed.for.the.production.of.nanopowders.using.mechanical.milling..The.first.one.is.milling.a.single.phase.powder.by.controlling.the.balance.point.between.fracturing.and.cold.welding17..By.this.way,.particles.larger.than.100.nm.cannot.be.excessively.cold.welded..As.a.result,.a.reduction.of.the.average.grain.size.from.50–100.?m.up.to.2–20.nm.is.obtained..The.reason.that.this.reduction.of.the.order.of.103–104.for.the.average.grain.size.occurs,.is.the.creation.and.self-organization.of.large-angle.grain.boundaries.between.the.powder.particles..The.mechanism.of.microstructure.formation.is.very.different.from.the.other.synthesis.methods,.but.the.final.microstructure.is.very.similar..A.severe.plastic.deformation.occurs.due.to.mechanical.attrition,.so.a.continuous.refinement.of.the.internal.structure.of.the.powder.particles.to.nanometer.scales.is.accomplished..Temperature.rises.during.the.process.over.100.°C–200.°C.19

While.mechanical.milling.is.very.sensitive.to.contamination,.atmospheric.control.can.be.used.for.chemical.reactions.between.the.environment.and.the.milled.powders18..This.has.led.to.the.development.of.a.novel,.cost.effective.method.of.producing.a.variety.of.nanopowders,.Mechanochemical.Processing.(MCP),.which.consists.the.second.method.of.mechanical.attrition..In.MCP.a.conventional.ball.mill.can.be.used.as.a.low.temperature.chemical.reactor..The.ball.mill.increases.the.reaction.kinetics.in.the.reacting.powder.mixture.as.a.result.of.the.intimate.mixing.and.refinement.of.the.grain.structure.to.the.nanometer.scale..The.reaction.occurs.during.the.actual.milling..For.this.reason,.a.proper.reactive.gas,.like.O2,.N2,.atmospheric.air,.etc..and.a.suitable.precursor.are.chosen..A.variety.of.metals.such.as.Ti,.Fe,.V,.Zr,.W,.Hf,.Ta.and.Mo.demonstrate.the.potential.of.reactive.milling20,.21;.they.can.be.transformed.to.nanocrystallines.of.metal.nitrides.and.oxides..Concerning.the.wet.milling,.an.organic.fluid.can.also.be.used..Metal.powder.can.be.transformed.to.nanocrystalline.metal-ceramic.composite.by.this.method..The.resulting.product.phase.is.formed.as.individual.single.nanometer.sized.grains,.in.a.by-product.matrix..For.this.reason,.it.is.necessary.to.confirm.that.the.reaction.has.finished,.so.temperature.heat.treatment.often.follows.the.process.

The.reduction.of.the.process.cost.and.the.industrialization.of.products.can.be.achieved.by.using.a.variety.of.precursors,.like.oxides,.carbonates,.sulphates,.chlorides,.fluorides,.hydroxides.and.others..Different.ball.mills.have.been.developed.for.mechanical.attrition,.such.as.tumbler.mills,.attrition,.shaker.mills,.vibratory.mills,.planetary.mills,.etc..22.The.method.includes.shaking.or.violent.agitation..The.material.powder.is.placed.in.a.sealed.container.with.coated.balls.by.hardened.steel.or.tungsten.carbide..The.mass.ratio.for.the.ball.to.the.powder.shall.be.5:10,.with.a.typical.particle.diameter.50.?m.for.the.powder..Kinetic.energy.of.balls.is.a.function.of.their.mass.and.velocity,.as.a.result,.steel.or.tungsten,.which.are.high.density.materials,.are.preferable.as.means.of.milling.

2.3..Hybrid.approach.–.nanolithography

Nanolithographic.technique.are.appropriate.for.the.fabrication.of.1D.nanostructures,.nanocatalysts,.semiconductors,.etc..They.include.electron-beam.or.focused-ion-beam.writing,proximal.probe.patterning,.X-ray.lithography23,.24.and.many.other.methods..Nanolithography.also.includes.dry.or.wet.etching..In.the.context.of.fabrication.of.nanostructures.the.definition.of.lithography.should.be.referred.not.only.as.a.top-down,.but.also.as.a.bottom-up.route..By.nanolithography,.nanostructures.or.their.arrays.can.be.synthesized,.by.a.directed.growth.process.or.by.a.constrained.growth.from.one.to.few.nanometers..The.advantage.of.these.methods.is.that.large.quantities.of.1D.nanostructures.can.be.prepared,.using.a.wide.variety.of.materials,.which.are.available.

3..Carbon-based.materials

3.1..Fullerenes

The.most.widely.studied.fullerene.is.the.C60.molecule.(also.known.as.Buckminsterfullerene).with.a.spherical.molecular.structure.of.~1.nm.in.diameter,.consisting.of.20.hexagonal.and.12.pentagonal.rings25,.26..There.are.also.fullerenes.with.higher.mass.such.as.C70,.C76,.C78.and.C80.with.different.geometric.structures..The.great.scientific.interest.in.fullerene.C60.can.be.explained.by.the.following.reasons:.(i).it.can.be.abundantly.produced.in.the.carbon.soot.from.carbon.evaporation.by.arc.discharge,.(ii).it.has.high.symmetry.(icosahedral.Ih.with.all.60.carbons.chemically.equivalent),.(iii).it.is.less.expensive,.(iv).it.is.relatively.inert.under.mild.conditions.and.(v).it.is.less.toxic..Generally,.fullerenes.possess.unique.properties.such.as.super.conductivity.and.anti-oxygen.activity.

The.most.common.laboratory-based.methods.of.synthesis.for.fullerenes.are.the.following.two.methods:.the.arc.discharge.of.graphite.electrodes.in.200.Torr.in.the.presence.of.He.(Krätschmer-Huffman.method),.leading.to.yields.of.up.to.70%.of.C60.and.15%.of.C70.and.the.gas.combustion.method.where.a.continuous.low.flow.of.hydrocarbon.fuel.(e.g..benzene,.acetylene).is.burned.at.low.pressure.in.the.presence.of.oxygen..The.latter.method.has.the.advantage.of.producing.large.clusters.of.fullerenes.(that.are.only.produced.in.low.yield.by.the.arc-discharge.method),.whose.size.distribution.can.be.easily.controlled.by.varying.the.parameters.of.combustion..Moreover,.the.doping.of.clusters.is.readily.achieved.by.introducing.dopants.in.the.combustion.mixture..Those.methods.have.been.successfully.adapted.to.the.large-scale.production.of.fullerenes.

Particularly.the.gas.combustion.method.enabled.the.production.of.fullerenes.in.tonnes-per-year..Furthermore,.laser.vaporization.is.also.employed.for.fullerene.production,.using.an.apparatus.of.a.pulsed.Nd:YAG.laser.as.the.laser.source,.operating.at.532.nm.and.250.mJ.of.power.and.the.graphite.target.keeping.it.at.1200.°C.in.a.furnace.

Fullerene/fullerene.clusters.produced.with.the.aforementioned.methods.are.in.the.form.of.a.crude.mixture.containing.C60.and.other.C.n.(n.>.60).as.well.as.conventional.hydrocarbon.species..For.their.isolation.from.the.crude.soot,.purification.methods.are.applied.such.as.Soxhlet.extraction.with.toluene.(in.which.fullerenes.are.soluble).and.with.ethers.(e.g..diethyl.ether).to.remove.the.soluble.impurities.of.hydrocarbons.and.accordingly.isolation.of.pure.C60.and.other.individual.fullerenes.employing.chromatographic.methods..Liquid.Chromatography.(LC).has.been.used.since.1990.for.the.fullerenes’.separation,.isolation.and.purification..This.method.is.also.used.to.control.reactions.of.fullerenes.such.as.nucleophilic.additions,.cycloadditions,.hydrogenations.and.oxidations.with.electrophiles..Typically.in.chromatographic.methods.two.phases.are.used,.a.mobile.phase.and.a.stationary.phase..Here,.the.mobile.phase.is.an.aromatic.solvent.with.high.fullerene.solubility,.sometimes.to.which.the.addition.of.a.non-aromatic.solvent.with.comparatively.low.fullerene.solubility.enhances.the.efficiency.of.fullerene.separation..As.a.stationary.phase.different.sorbents.can.be.used.with.relatively.high.affinity.for.the.fullerenes..A.variety.of.stationary.phases.have.been.used.so.far,.such.as.normal.and.reversed.or.charge-transfer.stationary.phases,.using.LC.or.HPLC.(high.performance.liquid.chromatography).and.moreover.size.exclusion.stationary.phases.in.gel.permeation.chromatography,.but.most.of.them.are.limited.to.gram.scale.separations..Therefore,.the.research.now.focuses.on.finding.more.selective.stationary.phases.mainly.based.on.charge-transfer.Chromatography..The.development.of.improved.chromatographic.methods.would.provide.higher.efficacy.and.better.resolution.concerning.fullerene.separation.at.both.analytical.and.preparative.scales,.and.at.the.lowest.cost..One.such.economically.viable.solution.is.the.use.of.a.cheap.stationary.phase.of.celite.(a.naturally.occurring,.soft,.chalk-like.sedimentary.rock).in.combination.with.activated.carbon.and.silica.gel.

The.first.commercial.usage.of.fullerenes.reported.in.2003.in.10-pin.bowling.balls.as.a.coating.of.resin.containing.fullerenes..Such.coating.prevents.ball.from.wearing.and.enhances.its.controllability..The.authors.count.today.24.registered.fullerene.suppliers,.19.of.which.are.manufacturers.mainly.based.in.the.United.States.and.the.others.in.Europe.and.Asia..However,.a.wide.range.of.fullerene.C60.prices.still.exist.beginning.from.US.$20.per.gram.and.extending.to.US.$180.per.gram.for.99%.purity..Their.high.cost.and.small.unit.sales.sizes.compared.to.other.nanoparticles,.discourage.their.widespread.usage,.although.a.large.array.of.potential.applications.has.been.identified,.including.optics,.electronics/IT.(information.technology).devices,.diagnostics,.pharmaceuticals,.environmental.and.energy.industries.

3.2..Carbon.nanotube.and.carbon.nanofibres

Both.CNTs.and.CNFs.are.graphitic.filaments.with.diameters.ranging.from.0.4.to.500.nm.and.are.available.in.varying.lengths,.up.to.several.hundred.micrometers,.depending.on.the.production.method..SWCNTs.are.composed.of.a.single.cylindrical.sheet.of.graphene.and.MWCNTs.several.concentric,.coaxical.rolled.up.graphene.sheets..Specifically,.the.CNT.diameters.are.typically.0.4.to.2.nm.and.up.to.200.nm.for.single-walled.carbon.nanotubes.(SWCNTs).and.multi-walled.carbon.nanotubes.MWCNTs),.respectively..CNFs.are.formed.by.graphene.nanocones.or.”cups”,.sometimes.are.referred.to.as.”stacked-cup.carbon.nanotubes”.with.diameters.ranging.from.70.to.200.nm.depending.upon.the.carbon.nanofibre.type.

After.the.discovery.of.CNTs.by.Iijima.in.1991,.CNTs.and.CNFs.have.attracted.the.scientific.interest.owing.to.their.excellent.physicochemical,.electrical.and.mechanical.properties..SWCNTs.can.be.metallic.or.semiconducting.depending.on.the.orientation.of.graphitic.filaments;.individual.SWCNTs.can.have.a.thermal.conductivity.of.3500.W.m?1.K?1.at.room.temperature,.exceeding.the.thermal.conductivity.of.diamond..Their.applications.in.the.area.of.polymer.composites.as.fillers,.microelectronics,.energy.storage.and.sensors.have.been.widely.reported..CNTs.and.CNFs.are.usually.obtained.by.CVD.method.from.the.decomposition.of.gaseous.hydrocarbon.over.transition.metal-catalyst.particles..Other.methods.such.as.flame.synthesis,.arc.discharge.and.laser.ablation.are.too.energy.intensive,.expensive.and.result.in.less.yield.compared.to.CVD..The.CVD.method.is.the.most.dominant.technique.for.mass.production.of.CNTs.due.to.its.easy.scaling-up..However,.the.most.common.problem.is.focused.on.their.purity,.which.decreases.with.increased.yield..Their.synthesis.routes.at.laboratory.scale.can.be.easily.monitored,.in.order.to.tailor.their.final.properties..Industrial.equipment.is.more.sophisticated.and.complex.in.design,.as.compared.to.laboratory.CVD.equipment.due.to.its.accommodation.of.large-scale.deposition.

The.production.of.both.nanomaterials.in.large.scale.can.result.in.difficulties.as.the.same.technique.is.applied.in.large.reaction.vessels.decreasing.their.purity.and.broadening.diameter.distribution27,.28..Taking.into.account.their.increasing.demand,.a.more.refined.method.permitting.the.control.of.parameters.and.reduction.of.contaminations.is.needed.to.be.established.in.order.their.mass.production.to.be.further.developed.with.less.defects.

CNT-related.commercial.activity.has.been.reported.more.substantially.during.the.past.decade..The.CNT.production.capacity.as.well.as.annual.number.of.journal.publications.and.patents.follows.an.increased.growth..Globally,.the.yearly.CNT.production.capacity.is.estimated.to.be.~300.tons.MWCNTs.and.~7.tons.SWCNTs,.while.their.anticipated.demand.would.exceed.1000.tons/year.in.the.near.future..Their.commercially.available.price.can.reach.~$1/g.and.~$500/g.for.MWCNTs.and.SWCNTs,.respectively.rendering.CNT-based.products.more.expensive.up.to.10.times.than.prevalent.ones..SWCNT.synthesis.by.CVD.requires.much.tighter.process.control.compared.to.MWCNTs’,.rendering.their.prices.orders.of.magnitude.higher.than.of.MWCNTs’..As.mentioned.before,.SWCNTs.have.metallic.or.semiconducting.behavior.and.their.price.depend.on.this..CoMoCat®.SWCNTs.cost.up.to.€500.for.1.g.with.98%.of.semiconducting.SWCNTs..For.this.reason,.the.electronic.industry.has.lost.interest.for.them.because.it.is.not.possible.to.completely.control.their.chirality.and.it.was.too.difficult.to.handle.them.at.low.costs..Indeed.it.is.not.the.more.cost-effective.production.of.SWCNT.that.it.is.the.real.problem;.the.real.problem.is.focused.on.controlling.their.electronic.behaviour..Therefore,.MWCNTs,.being.metallic,.are.preferred.for.applications.where.diameter.is.not.a.crucial.parameter;.the.development.of.more.cost-effective.SWCNT.production.techniques.is.required.in.order.to.obtain.industrial.entity..Aixtron.company.is.leader.on.CNTs.market.and.has.developed.an.industrial.machinery.for.CNTs.growth..shows.the.Global.market.for.CNTs.grades.based.on.committed.production,.2011–2016

 

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Antibiotic inhibition mechanisms against
bacteria are well known; however, metabolic interactions and cross talk with
host and pathogen is mostly uncharacterized. While there is widespread use of subtherapeutic
doses of antibiotics in animals for growth promotion, the exact metabolite
shifts are unknown. A precise elucidation of antibiotic host-pathogen metabolic
interaction can lead to well targeted approach in combating pathogens and
promoting animal growth. Current methods for testing antibiotic efficacy is in
vitro, which does not provide the host-pathogen context, this study uses a
novel approach by employing intestinal organoid as an ex vivo model for
antibiotic efficacy.

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