Low Particle Concentrations Research Articles

Low number concentration of ice nucleating particles in an aged smoke plume

Smoke from forest fires in the western part of North America reached the High Altitude Research Station Jungfraujoch, Switzerland, at the beginning of September 2017. Number concentration of ice nucleating particles (INPs) active at −15 °C or warmer decreased by about half during its passage. This is different to observations of enhanced INP concentrations in fresh plumes from forest fires. We hypothesise that INPs initially present in a smoke plume are lost or deactivated during long‐range transport, while components of smoke capable of deactivating INPs originally present or mixed later into the plume continue to remain active across a longer distance.

Weak Coupling Effect on the Magnetic Freedericksz Transition in a Ferronematic Liquid Crystal

The magnetic Freedericksz transition in a ferronematic representing a diluted suspension of magnetic nanoparticles in an N-(4-methoxybenzylidene)-4-butylaniline (MBBA) nematic liquid crystal was experimentally studied. The transition point was determined by means of dielectric capacitance measurements in cells of different thickness for samples with various volume fractions of ferroparticles. The effect of weak coupling between the magnetic and liquid-crystal subsystems was studied. Low concentrations of quasispherical magnetic particles were shown to decrease the magnetic Freedericksz transition threshold in comparison with a pure liquid crystal. The obtained results were theoretically substantiated. The phase diagram of the suspension was plotted, and the method of estimating the energy of coupling between magnetic particles and a liquid-crystal matrix was proposed.

Harnessing clay nano-particles for stem-cell driven tissue regeneration, EPSRC

Gels made from clay could provide an environment able to stimulate stem-cells due to their ability to bind biological molecules. That molecules stick to clay has been known by scientists since the 1960s. Doctors observed that absorption into the blood stream of certain drugs was severely reduced when patients were also receiving clay-based antacid or anti-diarrhoeal treatments. This curious phenomenon was realized to be due to binding of the drugs by clay particles. This interaction is now routinely harnessed in the design of tablets to carefully control the release and action of a drug. Dr Dawson now proposes to use this property of clay to create micro-environments that could stimulate stem cells to regenerate damaged tissues such as bone, cartilage or skin. The rich electrostatic properties of nano (1 millionth of a millimetre) -scale clay particles which mediate these interactions could allow two hurdles facing the development of stem-cell based regenerative therapies to be overcome simultaneously. The first challenge - to deliver and hold stem cells at the right location in the body - is met by the ability of clays to self-organise into gels via the electrostatic interactions of the particles with each other. Cells mixed with a low concentration (less than 4%) of clay particles can be injected into the body and held in the right place by the gel, eliminating, in many situations, the need for surgery. Clay particles can also interact with large structural molecules (polymers) which are frequently used in the development of materials (or 'scaffolds'), designed to host stem cells. These interactions can greatly improve the strength of such structures and could be applied to preserve their stability at the site of injury until regeneration is complete. While several gels and scaffold materials have been designed to deliver and hold stem cells at the site of regeneration, the ability of clay nanoparticles to overcome a second critical hurdle facing stem-cell therapy is what makes them especially exciting. Essential to directing the activity of stem-cells is the carefully controlled provision of key biological signalling molecules. However, the open structures of conventional scaffolds or gels, while essential for the diffusion of nutrients to the cells, means their ability to hold the signalling molecules in the same location as the cells is limited. The ability of clay nano-particles to bind biological molecules presents a unique opportunity to create local environments at a site of injury or disease that can stimulate and control stem-cell driven repair. Dr Dawson's early studies investigated the ability of clay gels to stimulate the growth of new blood vessels by incorporating a key molecular signal that stimulates this process, vascular endothelial growth factor (VEGF). In a manner reminiscent of the observations made in the 60s, Dr Dawson and colleagues observed that adding a drop of clay gel to a solution containing VEGF caused, after a few hours, the disappearance of VEGF from the solution as it became bound to the gel. When placed in an experimental injury model, the gel-bound VEGF stimulated a cluster of new blood vessels to form. These exciting results indicate the potential of clay nanoparticles to create tailor-made micro-environments to foster stem cell regeneration. Dr Dawson is developing this approach as a means of first exploring the biological signals necessary to successfully control stem cell behaviour for regeneration and then, using the same approach, to provide stem cells with these signals to stimulate regeneration in the body. The project will seek to test this approach to regenerate bone lost to cancer or hip replacement failure. If successful the same technology may be applied to harness stem cells for the treatment of a whole host of different scenarios, from burn victims to those suffering with diabetes or Parkinson's.

New insights into the formation of silver-based nanoparticles under natural and semi-natural conditions

For the first time, the natural formation of silver-based nanoparticles (Ag-b-NPs) was studied in field investigations of two pre-alpine lakes in Germany that contain geogenic silver traces in the sub-ng L−1 range. Light-sensitive microorganisms most likely accumulate and transport these silver traces from deeper water layers to the surface. At the surface of the eutrophic lake, approximately 40% of total silver (5.7 ng L−1) consisted of Ag-b-NPs, whereas in the oligotrophic lake with similar enrichment of silver species, no Ag-b-NPs were detected. Additional lab experiments with nature-related Ag(I) concentrations in the lower-ng L−1 range and natural organic matter with total organic carbon values of ≤5 mg L−1 revealed that, contrary to common interpretation in the literature, Ag-b-NPs are also or even preferably formed in the dark. Particle size increases gradually with increasing reaction time, showing that Ostwald ripening occurs even at such low particle concentrations. When sulfide ions are present, smaller Ag-b-NPs with a narrower size distribution are formed.

Ultraclean Layers and Optically Thin Clouds in the Stratocumulus-to-Cumulus Transition. Part II: Depletion of Cloud Droplets and Cloud Condensation Nuclei through Collision–Coalescence

In Part I, aircraft observations are used to show that ultraclean layers (UCLs) in the marine boundary layer (MBL) are a common feature of the stratocumulus-to-cumulus transition (SCT) region over the northeast Pacific. The ultraclean layers are defined as layers of either cloud or clear air in which the concentration of particles with diameter larger than 0.1 μm is below 10 cm−3. Here, idealized microphysical parcel modeling shows that in the cumulus regime, collision–coalescence can strongly deplete cloud droplet concentration in cumulus (Cu) updrafts, thereby removing cloud condensation nuclei (CCN) from the atmosphere, suggesting that collision scavenging is likely the key process causing the low particle concentration in UCLs. Furthermore, the model results suggest that the stratocumulus regime is typically not favorable for UCL formation, because condensate amounts are generally not large enough to deplete drops in the time it takes to loft air to the upper planetary boundary layer (PBL). A bulk parameterization of the coalescence-scavenging rate is derived based on in situ measurements. The fractional coalescence-scavenging rate is found to be strongly dependent upon liquid water content (LWC) and, hence, the height above cloud base, indicating that a higher cloud top and thus a greater cloud thickness in a Cu updraft is an important factor accounting for the observed sharp rise of UCL coverage in the SCT region. An important implication is that PBL height, which controls maximum cloud thickness, and therefore LWC in updrafts, could be a crucial factor constraining coalescence scavenging and thus the formation of UCLs in the MBL.

Investigation on microstructure and properties of electrodeposited Ni-Ti-CeO2 composite coating

Ternary Ni-Ti-CeO2 composite coatings were synthesized from Watts bath containing various concentrations of mixed particles including Ti microparticles and CeO2 nanoparticles (fixed ration 10: 1 by weight) by electrodeposition. Microstructures of the composite coatings were comprehensively investigated by XRD, SEM, AFM and TEM. The incorporation of mixed particles gave birth to grain refinement, attenuation of soft mode [200] texture and random-orientated grain growth of nickel deposits. Typically, as for the composite coating electrodeposited form Watts bath containing relatively low concentrations (less than 22 g/L) of mixed particles, the presence of pores inside the coatings, asperities on the surface and cluster-like distribution of Ti microparticles in composite coating, restricted the improvement of properties. By increasing concentration of mixed particles to 88 g/L, high-quality Ni-Ti-CeO2 composite coating with uniformly distributed Ti microparticles was achieved. The incorporation of Ti microparticles should take great responsibility for the presence of pores and asperities, while the incorporation CeO2 nanoparticles played very important role in the formation of dense and smooth composite coatings. Microhardness and wear resistance were also improved by increasing contents of mixed particles in composite coatings. The incorporation of mixed particles leaded to increasement of friction coefficient and the friction coefficient presented increasing tendency by increasing the concentrations of mixed particles in Watts bath.

On the transition between turbulence regimes in particle-laden channel flows

Turbulent wall-bounded flows exhibit a wide range of regimes with significant interaction between scales. The fluid dynamics associated with single-phase channel flows is predominantly characterized by the Reynolds number. Meanwhile, vastly different behaviour exists in particle-laden channel flows, even at a fixed Reynolds number. Vertical turbulent channel flows seeded with a low concentration of inertial particles are known to exhibit segregation in the particle distribution without significant modification to the underlying turbulent kinetic energy (TKE). At moderate (but still low) concentrations, enhancement or attenuation of fluid-phase TKE results from increased dissipation and wakes past individual particles. Recent studies have shown that denser suspensions significantly alter the two-phase dynamics, where the majority of TKE is generated by interphase coupling (i.e. drag) between the carrier gas and clusters of particles that fall near the channel wall. In the present study, a series of simulations of vertical particle-laden channel flows with increasing mass loading is conducted to analyse the transition from the dilute limit where classical mean-shear production is primarily responsible for generating fluid-phase TKE to high-mass-loading suspensions dominated by drag production. Eulerian–Lagrangian simulations are performed for a wide range of particle loadings at two values of the Stokes number, and the corresponding two-phase energy balances are reported to identify the mechanisms responsible for the observed transition.

Discontinuous contact line motion of evaporating particle-laden droplet on superhydrophobic surfaces.

The three-phase contact line motion on a superhydrophobic surface through particle-laden sessile droplet evaporation was investigated. Sample surfaces with micro- and nanoscale structures were generated by various durations of chemical treatment and SiO_{2} spherical particles with different sizes were used as additives of test liquid. The contact angle and contact radius profiles were studied, and the discontinuous motion of those profiles on micro- and nanostructured hierarchical surfaces was observed, while it was not observed on a nanostructured superhydrophobic surface. Suspensions with low particle concentration induced a relatively large contact radius jump compared to the high-concentrated condition; in contrast, the previous report showed the opposite trend for flat surfaces. In order to explain this result, a simple explanation was provided-that the stacked particles at the contact line region suppressed to the deformation of the liquid-vapor interface near the contact line. This is confirmed by side-view images of the deposition results because the contact line region after evaporation of the dense suspension showed a large contact angle compared to that of the diluted suspension. In addition, deposition at the contact line region was observed by scanning electron microscopy to discuss the effect of the characteristic length scale of the surface structure and particles on the contact line motion. We believe that these results will help one to understand the deposition phenomenon during particle-laden droplet evaporation on the superhydrophobic surface and its applications such as evaporation-driven materials deposition.

Effect of Relative Humidity on Particulate Matter Concentration and Visibility During Winter in Chengdu

The effect of relative humidity (RH) on particulate matter concentrations and atmosphere visibility were investigated using the continuous on-line observed data of Chengdu city during December 2015, including RH, visibility, the concentrations of particulate matters (PM10, PM2.5 and PM1) and gaseous pollutants (SO2 and NO2), and the concentrations of SO42- and NO3- in PM2.5. The results showed that the haze process occurred because of the synergistic effects of higher particulate matter concentrations and RH, leading to the reduction of visibility. The average ratio of PM2.5 to PM10 was 64% and it significantly increased with the increase of RH during observation period, which indicated that the pollution of fine particles during winter in Chengdu was serious, and high RH aggravated the pollution caused by fine particles.Visibility decreased exponentially with the increase of particulate matter concentrations. When RH was higher, visibility was lower at the same concentrations of particulate matter.RH had a strong effect on visibility at lower particle concentrations, while the effect of RH on the visibility decreased, and atmospheric extinction was controlled by PM2.5 concentrations at higher particle concentrations. With RH increasing from less than 40% to more than 70%, the average sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) increased from 0.27 and 0.11 to 0.40 and 0.19, respectively, indicating that higher RH significantly promoted the formation of secondary sulfate and nitrate. Secondary sulfate and nitrate separately or coordinatively influenced the air quality.

Flow and heat transfer behaviour of nanofluids in microchannels

Flow and heat transfer of aqueous based silica and alumina nanofluids in microchannels were experimentally investigated. The measured friction factors were higher than conventional model predictions at low Reynolds numbers particularly with high nanoparticle concentrations. A decrease in the friction factor was observed with increasing Reynolds number, possibly due to the augmentation of nanoparticle aggregate shape arising from fluid shear and alteration of local nanoparticle concentration and nanofluid viscosity. Augmentation of the silica nanoparticle morphology by fluid shear may also have affected the friction factor due to possible formation of a core/shell structure of the particles. Measured thermal conductivities of the silica nanofluids were in approximate agreement with the Maxwell-Crosser model, whereas the alumina nanofluids only showed slight enhancements. Enhanced convective heat transfer was observed for both nanofluids, relative to their base fluids (water), at low particle concentrations. Heat transfer enhancement increased with increasing Reynolds number and microchannel hydraulic diameter. However, the majority of experiments showed a larger increase in pumping power requirements relative to heat transfer enhancements, which may hinder the industrial uptake of the nanofluids, particularly in confined environments, such as Micro Electro-Mechanical Systems (MEMS).

Experimental analysis for heat transfer of nanofluid with wire coil turbulators in a concentric tube heat exchanger

Abstract Nanofluids are a novel class of heat transfer suspensions of metallic or nonmetallic nanopowders with a size of less than 100 nm in base fluids and they can increase heat transfer potential of the base fluids in various applications. In the last decade, nanofluids have become an intensive research topic because of their improved thermal properties and possible heat transfer applications. For comparison, an experiment using water as the working fluid in the heat exchanger without wire coils was also performed. Turbulent forced convection heat transfer and pressure drop characteristics of Al2O3-water nanofluids in a concentric tube heat exchanger with and without wire coil turbulators were experimentally investigated in this research. Experiments effected particle volume concentrations of 0.4–0.8 to 1.2–1.6 vol% in the Reynolds number range from 4000 to 20,000. Two turbulators with the pitches of 25 mm and 39 mm were used. The average Nusselt number increased with increasing the Reynolds number and particle concentrations. Moreover, the pressure drop of the Al2O3-water nanofluid showed nearly equal to that of pure water at the same Reynolds number range. As a result, nanofluids with lower particle concentrations did not show an important influence on pressure drop change. Nonetheless, when the wire coils used in the heat exchanger, it increased pressure drop as well as the heat transfer coefficient.

Remote quantification of Cochlodinium polykrikoides blooms occurring in the East Sea using geostationary ocean color imager (GOCI)

Accurate and timely quantification of widespread harmful algal bloom (HAB) distribution is crucial to respond to the natural disaster, minimize the damage, and assess the environmental impact of the event. Although various remote sensing-based quantification approaches have been proposed for HAB since the advent of the ocean color satellite sensor, there have been no algorithms that were validated with in-situ quantitative measurements for the red tide occurring in the Korean seas. Furthermore, since the geostationary ocean color imager (GOCI) became available in June 2010, an algorithm that exploits its unprecedented observation frequency (every hour during the daytime) has been highly demanded to better track the changes in spatial distribution of red tide. This study developed a novel red tide quantification algorithm for GOCI that can estimate hourly chlorophyll-a (Chl a) concentration of Cochlodinium (Margalefidinium) polykrikoides, one of the major red tide species around Korean seas. The developed algorithm has been validated using in-situ Chl a measurements collected from a cruise campaign conducted in August 2013, when a massive C. polykrikoides bloom devastated Korean coasts. The proposed algorithm produced a high correlation (R2=0.92) with in-situ Chl a measurements with robust performance also for high Chl a concentration (300mg/m3) in East Sea areas that typically have a relatively low total suspended particle concentration (<0.5mg/m3).

Strong control of Southern Ocean cloud reflectivity by ice-nucleating particles

Large biases in climate model simulations of cloud radiative properties over the Southern Ocean cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated Southern Ocean clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the Southern Ocean radiation bias. The very low ice-nucleating particle concentrations that prevail over the Southern Ocean strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions.

The effect of cell density, proximity, and time on the cytotoxicity of magnesium and galvanically coupled magnesium-titanium particles in vitro.

Magnesium (Mg) and galvanically coupled magnesium-titanium (Mg-Ti) particles in vitro have been reported previously to kill cells in a dosage-dependent manner. Mg-Ti particles kill cells more effectively than Mg alone, due to the galvanic effect of Mg and Ti. This study further investigated the in vitro cytotoxicity of Mg and Mg-Ti in terms of particle concentration, cell density, time, and proximity. Cell density has an effect on cell viability only at low particle concentrations (below 250 µg/mL), where cell viability dropped only for lower cell densities (5000-10,000 cells/cm2 ) and not for higher cell densities (20,000-30,000 cells/cm2 ), showing that the particles cannot kill if there are more cells present. Cytotoxicity of Mg and Mg-Ti particles is quick and temporary, where the particles kill cells only during particle corrosion (first 24 h). Depending on the percentage of surviving cells, particle concentrations, and ongoing corrosion activity, the remaining live cells either proliferated and recovered, or just remained viable and quiescent. The particle killing is also proximity-dependent, where cell viability was significantly higher for cells far away from the particles (greater than ∼1 mm) compared to those close to the particles (less than ∼1 mm). Although the increase of pH does affect cell viability negatively, it is not the sole killing factor since cell viability is significantly dependent on particle type and proximity but not pH. Mg and Mg-Ti particles used in this study are large enough to prevent direct cell phagocytosis so that the cell killing effect may be attributed to solely electrochemical reactions. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1428-1439, 2018.

Comparison study on air flow and particle dispersion in a typical room with floor, skirt boarding, and radiator heating systems

In the present study, air flow and particle dispersion were simulated in a room using a three dimensional model when a thermal manikin was present in the room. The room was tested with three heating systems: floor heating, skirt boarding heating, and radiator heating systems. Airflow velocity and temperature distributions were obtained in terms of room's height in different places of the room. Three particle sizes as well as two locations of particle injection were studied. An Eulerian-Lagrangian model was used to predict the characteristics of air and particle phases. In the Lagrangian particle model, the effects of drag, lift, thermophoretic, and Brownian forces were considered. Results showed that the skirt boarding heating system due to uniform heat distribution and lower heat losses as well as providing a better thermal comfort condition, has the best performance among all the studied heating systems. The results of particle phase showed that the skirt boarding heating system has the lowest particle concentration in the breathing zone of the manikin. Furthermore, it was shown that due to the presence of thermal sources in the room, the particles have a small tendency to leave the room and they mostly settled on walls and ceiling or stayed at lower heights of the room.

Experimental investigation and prediction of the thermal conductivity of water-based oxide nanofluids with low volume fractions

Although there are already many models for prediction of the thermal conductivity of nanoparticle suspension, most of them only consider the cases for high nanoparticle volume fractions (often > 0.1%). Considering the cost of particle itself, pumping and transportation, dispersion stability, etc., low particle concentrations are obviously more preferred. The present study firstly experimentally investigated the thermal conductivity of some oxide colloid suspensions with low particle concentrations. It was found that the famous multi-sphere Brownian model (MSBM) showed a large deviation for thermal conductivity prediction when the particle concentrations are below 0.1%. By introducing an adjustable exponential constant, n, into the volume fraction item of MSBM, the predicted thermal conductivity can be in good agreement with experimental data for the particle volume fractions ranging from 0.001 to 10%. The dependency of n on the particle volume fraction and its possible physical significance were discussed in detail. It turns out that, when the volume fraction is larger than 1%, the modified model can be reduced to the original MSBM. The value of n approximately equals to 0.7 when the volume fractions of nanofluids are lower than 0.005%. Between these two volume fractions, n is found to follow a nearly linear relation with the logarithm of volume fraction. The validity of the modified MSBM model for practical supplication was further justified based on numerical method. The simulation results showed that our model has excellent agreement with Maxwell–Garnetts model in low volume fraction ranges due to the weak interaction between various nanoparticles in the system. Our study should be of value for numerical simulation and engineering design of nanofluids in the future.

Reducing the Coefficient of Thermal Expansion of Polyimide Films in Microelectronics Processing Using ZnS Particles at Low Concentrations

We report a reduction in the coefficient of thermal expansion (CTE) of polyimide (PI) film in microelectronics processing by using ZnS particles as nanofillers. To prevent agglomeration of ZnS particles, the surfaces of ZnS particles were modified with the (3-mercaptopropyl)trimethoxysilane, creating surface hydroxyl groups. For means of comparison, SiO2 and ZrW2O8 particles that have widely been studied as fillers for various polymer films were also synthesized. The CTE measurements showed that the ZnS particles produced PI nanocomposite film with a much lower CTE than either SiO2 or ZrW2O8 particles at the same concentration. In particular, the surface-modified ZnS particles showed the lowest CTE (13 ppm/K) at 15 wt %, which is comparable to the largest percentage decrease (70%) in CTE from the bare-PI film to date at a much lower particle concentration. To rationalize the significant reduction in CTE with the surface-modified ZnS particles, we considered the intrinsic CTE and thermal conductivity, ther...

Particle dispersion in a double-diffusive turbulent layer

We simulated the flow in a double diffusive turbulent layer using a periodic two-dimensional square computational domain. The conditions of the simulation correspond to those typically found in oceans (Pr = 7 and Sc = 1000) and results are in good agreement with the literature. When the flow was in statistically steady state we tracked the paths of particles with different inertia assuming that the concentration of particles is small and their mutual interaction and their effect on the carrying fluid can be neglected (one-way coupling). Numerical experiments were carried out to reveal the effect of the different terms of the particle force balance and the particle inertia in the preferential concentration of the particles. The different numerically obtained particle concentration distributions were analyzed using the cluster index or lacunarity, the tortuosity and the Voronoï analysis. The departure of the instantaneous particle distributions from random distributions using different box sizes for the calculation of the lacunarity of the distributions show maxima at box sizes corresponding to the Kolmogorov length scale. The novel application of the concept of tortuosity to the analysis of the instantaneous particle distributions reveals the non-isotropic character of the particle distributions. The Voronoï analysis indicates larger areas of the voids and clusters for the simulations considering only the drag force in comparison with simulations considering all the terms of the particle force balance. These observations are consequence of the role of the stress gradient term which generates high particle concentrations along the boundaries of the ascending and descending concentration plumes and relatively low particle concentrations in the tail and head of the plumes.

Breakup of nanoparticle clusters using Microfluidizer M110-P

A commercial design, bench scale microfluidic processor, Microfluidics M110-P, was used to study the deagglomeration of clusters of nanosized silica particles. Breakup kinetics, mechanisms and the smallest attainable size were determined over a range of particle concentrations of up to 17% wt. in water and liquid viscosities of up to 0.09Pas at 1% wt. particle concentration. The device was found to be effective in achieving complete breakup of agglomerates into submicron size aggregates of around 150nm over the range covered. A single pass was sufficient to achieve this at a low particle concentration and liquid viscosity. As the particle concentration or continuous phase viscosity was increased, either a higher number of passes or a higher power input (for the same number of passes) was required to obtain a dispersion with a size distribution in the submicron range.Breakup took place through erosion resulting in a dispersion of a given mean diameter range regardless of the operating condition. This is in line with results obtained using rotor-stators. Breakup kinetics compared on the basis of energy density indicated that whilst Microfluidizer M110-P and an in-line rotor-stator equipped with the emulsor screen are of similar performance at a viscosity of 0.01Pas, fines volume fraction achieved with the Microfluidizer was much higher at a viscosity of 0.09Pas.

Improvement in Adhesive Performance of Single-Lap Joining Composite Lamınates by Using Nano-Montmorillonite Modified Epoxy

Nanoparticles have been widely used as reinforcing materials related to polymer matrices for outstanding performance. In this paper expresses modified epoxy adhesives which are enhanced conventional adhesives widely used in industry. In this study, nano-montmorillonite (nano-MMT) (1% to 5% by weight) was mixed into the epoxy resin by using ultrasonication to obtain toughened adhesives. Carbon fiber reinforced composites was used as adherent material and it’s were prepared according to ASTM D5868-01. It has been clearly revealed that the additions of low concentrations of nanosized particles (2 % by weight) performed higher mechanical strength than others and also show lower adhesive performance with increased nano-MMT weight percentage. According to the lap shear test results, shear strength was significantly increased with addition of 2wt% nano-MMT and the strengths of the joints were found to be 12.5% higher than neat epoxy adhesives.