Plate-like Crystals Research Articles

Lack of phospholipids in bile enhances cholesterol cholelithogenesis in the ATP‐binding cassette transporter B4 (Abcb4) knockout mice

BackgroundBiliary phospholipids play a key role in transporting cholesterol (Ch) by forming unilamellar and multilamellar vesicles that display a significantly higher ability to solubilize Ch in bile compared to simple and mixed micelles. The ATP‐binding cassette transporter B4 (ABCB4) is responsible for hepatic phospholipid secretion and its deletion in the liver causes a lack of phospholipids in bile of mice. Our aim is to explore whether targeted deletion of the Abcb4 gene in the liver leads to more rapid Ch crystallization and gallstone formation in Abcb4 knockout (KO) mice fed even a low Ch diet compared to wild‐type (WT) mice.MethodsThe critical role of biliary phospholipids in Ch crystallization and gallstone formation was investigated by physical‐chemical methods in male Abcb4 KO vs WT mice fed a chow diet (on day 0) and a special diet containing 0.1% Ch, 15% butterfat and 0.25% cholic acid for 4 wk.ResultsOn the chow diet (day 0), biliary phospholipids are 18.1±0.3 mM in pooled gallbladder bile of WT mice. However, no phospholipids are detected in Abcb4 KO mice fed either the chow or the special diet. After 1 wk of feeding the special diet, phase diagram analysis finds that lipid composition of pooled gallbladder bile of Abcb4 KO mice is located in crystallization region A. Moreover, many needle‐like Ch crystals, typical Ch monohydrate crystals, sandy stones and small gallstones (0.1–0.2 mm in diameter), but not liquid crystals, are detected in bile by phase contrast and polarizing light microscopy. This shows that lack of phospholipids in bile produces anhydrous crystalline metastable intermediates that rapidly evolve to Ch monohydrate crystals from supersaturated bile. In contrast, lipid composition of pooled gallbladder bile of WT mice is still within the micellar zone, indicating that bile is unsaturated with Ch. After 4 wk of feeding the special diet, lipid composition of pooled gallbladder bile of Abcb4 KO mice still stays in crystallization region A, with many larger gallstones (0.3–0.6 mm in diameter) being formed in the gallbladder. Notably, lipid composition of pooled gallbladder bile of WT mice enters crystallization region C, as analyzed by phase diagram. Thus, many liquid crystals (i.e., unilamellar and multilamellar vesicles) and classical solid plate‐like Ch monohydrate crystals, but not gallstones, are found in the gallbladder of WT mice. These results indicate that solid Ch crystals are formed through the liquid crystalline pathway in WT mice.ConclusionsLack of biliary phospholipids caused by the Abcb4 deletion in the mouse liver is a critical risk factor for Ch gallstone disease by significantly reducing Ch solubility in bile through disrupting the liquid crystalline pathway, whereas it leads to more rapid Ch crystallization via the anhydrous crystalline pathway. Our findings provide novel insight into the pathophysiological mechanisms of why Ch gallstones are rapidly formed in patients with the ABCB4 mutations, thereby leading to low phospholipid‐associated cholelithiasis, a rare biliary disease caused by a single‐gene mutation.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Study on a Nano-Microstructure and Properties of Geopolymer by Recycling Integrated Gasification Combined Cycle Coal Ash Slag.

In this study, a geopolymer having a nano-scaled structure was fabricated using recycling fly ash slag discharged from IGCC (Integrated Gasification Combined Cycle), to assess the possibility of employing it to replace high strength concrete. Strength, density, crystal phase, and bonding structure, were measured and the nano-size crystal phase of the geopolymers was observed as a function of experimental parameters such as water-to-solid ratio (w/s ratio), flow of paste, and amount of sodium silicate in the alkali activator, NaOH. The geopolymer prepared with NaOH containing 50~70% sodium silicate and a w/s ratio of 0.26~0.28 showed a compressive strength of 75~80 MPa, which satisfied the design standard for high strength concrete in Korea, 40 MPa. The specimen made with NaOH containing 55% sodium silicate had plate-shaped crystals with a nanoscale size, 100 nm or less, and showed compressive strength of 77 MPa, 3.9 times higher than that made with only NaOH. From the viewpoint of microstructure, it was confirmed that nano-sized plate-like crystals and amorphous structure were both effective in improving the strength of the specimen. In conclusion, this study showed that high-strength geopolymer made from IGCC coal ash slag may replace cement used in building materials and concrete secondary products in the near future.

Sonofragmentation of two-dimensional plate-like crystals: Experiments and Monte Carlo simulations

A series of sonofragmentation experiments were performed by varying the sonication time and ultrasonic amplitude in order to investigate and simulate the two-dimensional ultrasound-assisted breakage of δ-form of pyrazinamide crystals using Monte Carlo (MC) method. An event driven constant number MC algorithm is presented to predict the evolution of two-dimensional size distribution of the product crystals. The MC simulations were performed by considering the breakage across the width of the particles and restricting the randomness of the break up point to a particular region along the length axis. The results obtained are in excellent agreement with the experimental observations. The proposed MC method reproduces both mode and span of the experimental size distribution with remarkable accuracy for all the cases. Further, it has only one tuning parameter depending on the ultrasonic amplitude. A graphical correlation has been obtained for selection of this tuning parameter for a given ultrasonic amplitude. Thus the proposed MC approach can be used to obtain quantitative view about the effect of sonofragmentation of two-dimensional plate-like crystals.

Competing stacking modes in crystals of trihalogeno-trimethyl-benzene: Theory meets experiment

The special case of the stacking of trihalogeno mesitylene (TXM) molecules has been investigated. Below 300 K, these molecules lead to needle shaped crystals in a triclinic arrangement. Thanks to DFT computations and an empirical atom-atom interaction model this packing mode has been rationalized. Aggregates of TXM molecules differently packed have been considered, namely dimers and trimers of type A, the molecules being piled one over the other along the axis a, and dimers B and trimers B, the molecules lying in the same bc plane. From the computations, it appears that the stabilizing energy of formation of a dimer of two molecules piled along a is several times larger than the energy gain obtained from the formation of a dimer of two neighbors in the bc plane. It has also been found that the energy of formation of a trimer of type A is approximately twice the energy of formation of a dimer A, so that an additive rule occurs. These conclusions are in perfect agreement with the experimental observations of the shape of the crystals obtained by crystallization from a super-saturated solution of TXM in an organic solvent: long needles with TXM molecules stacked along the axis a have always been obtained and never thin plate-like crystals.

In-plane doping profile control of plate-like organic single crystals grown by a method combining electrospray and low vapor pressure liquid film

Although the molecular doping of single crystal organic semiconductors is expected as a key technology that imparts attractive functions in optical and electrical properties, the doping technology in single crystal organic material is still in the initial stages. In this study, doping profile control in the organic single crystal was examined by using an organic single crystal growth method in which a low vapor pressure liquid thin film is used as a crystal growth field and solutes are supplied by electrospray deposition. Steep doping profile control with a transition region of around 1–2 μm was demonstrated using dopants of small molecule red dye and green fluorescent polymer into plate-like single crystal of widegap fluorescent small molecule. We also evaluated the doping profile of the small molecule red dye in microwire-like single crystals of green fluorescent metal complex small molecule.

Proteolysis by MMP20 Prevents Aberrant Mineralization in Secretory Enamel

The present study was conducted to investigate the role of proteolysis by matrix metalloproteinase 20 (MMP20) in regulating the initial formation of the enamel mineral structure during the secretory stage of amelogenesis, utilizing Mmp20-null mice that lack this essential protease. Ultrathin sagittal sections of maxillary incisors from 8-wk-old wild-type (WT), Mmp20-null (KO), and heterozygous (HET) littermates were prepared. Secretory-stage enamel ultrastructures from each genotype as a function of development were compared using transmission electron microscopy, selected area electron diffraction, and Raman microspectroscopy. Characteristic rod structures observed in WT enamel exhibited amorphous features in newly deposited enamel, which subsequently transformed into apatite-like crystals in older enamel. Surprisingly, initial mineral formation in KO enamel was found to proceed in the same manner as in the WT. However, soon after a rod structure began to form, large plate-like crystals appeared randomly within the developing KO enamel layer. As development continued, observed plate-like crystals became dominant and obscured the appearance of the enamel rod structure. Upon formation of these plate-like crystals, the KO enamel layer stopped growing in thickness, unlike WT and HET enamel layers that continued to grow at the same rate. Raman results indicated that Mmp20-KO enamel contains a significant portion of octacalcium phosphate, unlike WT enamel. Although normal in all other respects, large, randomly dispersed mineral crystals were observed in secretory HET enamel, although to a lesser extent than that seen in KO enamel, indicating that the level of MMP20 expression has a proportional effect on suppressing aberrant mineral formation. In conclusion, we found that proteolysis of extracellular enamel matrix proteins by MMP20 is not required for the initial development of the enamel rod structure during the early secretory stage of amelogenesis. Proteolysis by MMP20, however, is essential for the prevention of abnormal crystal formation during amelogenesis.

Microbial Mg-rich Carbonates in an Extreme Alkaline Lake (Las Eras, Central Spain).

This paper provides strong evidence for the contribution of the phylum Firmicutes in mediating the primary precipitation of Mg-rich carbonates (hydromagnesite, dolomite, magnesite, and nesquehonite) in recent microbialites from a highly alkaline and ephemeral inland lake (Las Eras, Central Spain). The carbonate mineral precipitation occurs sequentially as the microbial mats decay. Scanning electron microscopy (SEM) provided solid proof that hydromagnesite nucleation is initiated on the exopolymeric substances (EPS) and the microbial cells associated to the microbial mat degradation areas. The progressive mineralization of the EPS and bacterial cells by hydromagnesite plate-like crystals on their surface, results in the entombment of the bacteria and formation of radiating aggregates of hydromagnesite crystals. The hydrous phases, mostly hydromagnesite, were produced at a high percentage in the first stages of the microbial degradation of organic matter. When the availability of organic substrates declines, the heterotrophs tend to reduce their number and metabolic activity, remain dormant. At this stage, the anhydrous phases, dolomite and magnesite, nucleate on bacterial nanoglobules and/or collapsed cells. Evidence for the sequential formation of the Mg-rich carbonates trough the decay of organic matter by a fermentative EPS-forming bacterium isolated from the microbialites, Desemzia incerta, is drawn through a comparative analysis of carbonate formation in both natural and experimental settings. This study will help to constrain potential mechanisms of carbonate formation in natural systems, which are of fundamental importance not only for understanding modern environments but also as a window into the geologic past of Earth and potentially Mars.

Kinetic inhibition effect of Type I and III antifreeze proteins on unidirectional tetrahydrofuran hydrate crystal growth.

Experiments were performed to evaluate the kinetic inhibition effect of Type I and Type III antifreeze proteins (AFPs), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) on the growth of tetrahydrofuran (THF) clathrate hydrate crystals using the unidirectional growth technique. The crystal growth interface shifted under an applied temperature gradient over a given time. Type I AFP was the most effective kinetic inhibitor, followed by PVP, Type III AFP and PVA. The morphology of the THF hydrate was affected significantly by the concentration of Type I AFP. At low concentrations of Type I AFP, a large hexagonal plate-like crystal formed. At high concentrations, the growth interface became relatively flat. Conversely, at low concentrations of Type III AFP, the morphology of the THF hydrate crystal was unaffected by the additive.

Electrooptical determination of the isoelectric point of globular proteins: Cytochrome c adsorbed on montmorillonite nanoplates.

The purpose is to study the capability of the electric light scattering to determine the point of zero charge of native protein macromolecules adsorbed on colloid particles at low ionic strength and without using buffers. The chosen protein and particles are cytochrome c (cytC, globular haemoproteid) and montmorillonite (MM, negatively charged plate-like crystal). The pH-dependence of the electric polarizability γ(pH) in the range pH 6-11 shows minimum which coincides with the isoelectric point determined by measuring the electrophoretic mobility μ(pH) of the cytC-MM particles.

The physical presence of gallstone modulates ex vivo cholesterol crystallization pathways of human bile.

BackgroundCholesterol crystallization is an essential step toward gallstone formation. Although model bile studies showed that competition occurs between the gallstone surface and the surrounding aqueous phase for cholesterol molecules available for crystallization, this has not been investigated in human bile.MethodsFresh gallbladder bile was obtained during laparoscopic cholecystectomy from 13 patients with cholesterol (n = 10) or pigment (n = 3) stones. Small cholesterol gallstones were collected from another two patients. Both native and ultrafiltered bile with or without added gallstones was analysed by polarized light microscopy for the presence of arc-like and needle-like anhydrous cholesterol crystals and classic cholesterol monohydrate crystals. Weight of the added stones was evaluated before and after 21 days of bile incubation.ResultsIn unfiltered bile, the presence of stones was associated with a trend towards less anhydrous cholesterol crystals, but significantly more aggregated cholesterol monohydrate crystals. In ultrafiltered bile, the presence of stones tended to inhibit the formation of arc-like or needle-like crystals and was associated with significantly greater amounts of both plate-like and aggregated cholesterol monohydrate crystals. After 21 days of the incubation, stone weight was decreased in both unfiltered (–4.5 ± 1.6%, P = 0.046) and ultrafiltered bile (–6.5 ± 1.5%, P = 0.002). Bile from pigment-stone patients was clear in the absence of stones, but showed early appearance of plate-like and aggregated cholesterol monohydrate crystals in all samples to which cholesterol gallstones were added.ConclusionsThe physical presence of cholesterol gallstones in both native and filtered bile greatly influences cholesterol crystallization pathways. Whereas cholesterol monohydrate crystals increase, anhydrous cholesterol crystals tend to be inhibited. Detachment of solid cholesterol crystals from the gallstone surface may explain these findings.

Structural Characterization of Gallbladder Stones Using Energy Dispersive X-ray Spectroscopy and X-ray Diffraction.

Formation of the gallbladder stones is a common disease and a major health problem. The present study aimed to identify the structures of the most common types of gallbladder stones using X-ray spectroscopic techniques, which provide information about the process of stone formation. Phase and elemental compositions of pure cholesterol and mixed gallstones removed from gallbladders of patients were studied using energy-dispersive X-ray spectroscopy combined with scanning electron microscopy analysis and X-ray diffraction. The crystal structures of gallstones which coincide with standard patterns were confirmed by X-ray diffraction. Plate-like cholesterol crystals with laminar shaped and thin layered structures were clearly observed for gallstone of pure cholesterol by scanning electron microscopy; it also revealed different morphologies from mixed cholesterol stones. Elemental analysis of pure cholesterol and mixed gallstones using energy-dispersive X-ray spectroscopy confirmed the different formation processes of the different types of gallstones. The method of fast and reliable X-ray spectroscopic techniques has numerous advantages over the traditional chemical analysis and other analytical techniques. The results also revealed that the X-ray spectroscopy technique is a promising technique that can aid in understanding the pathogenesis of gallstone disease.

Experimental study of wax deposition pattern concerning deep condensate gas in Bozi block of Tarim Oilfield and its application

The Bozi block of the Tarim Oilfield is a typical tight sand condensate gas reservoir with serious wax plugging. So it is necessary to study the phase behavior and the wax deposition pattern of well fluids in Bozi gas reservoir, which will provide the phase enveloping diagram of the condensate gas and then help to control the paraffin deposition. In this study, the PVT tester and the self-designed microscopic solid deposition tester are used to get the phase enveloping line of the condensate gas. Such testing methods allow us to monitor phase changes of “gas-liquid-solid” system at different temperatures and pressures. In addition, the real reservoir conditions can be fully simulated with visibility. The result shows that the phase behaviors of the wax-containing condensate gas is extremely complex. Under different temperature and pressure, gas phase, gas-liquid, gas-solid, and gas-liquid-solid multiphase appear respectively. The main wax components of Bozi 104 well are C16∼C30, and their content is 0.111% mol per unit mole of condensate gas. The wax precipitation temperature of condensate oil is 15.4°C, the maximum instantaneous wax deposition volume is 0.2258% per unit mass of condensate oil, and its cumulative volume is 9.49% per unit mass of condensate oil. When the pressure is above the dew point, the solid wax is not dominated by the condensate oil but by long plate-like coarse wax crystals. When the pressure is below the dew point, the solid wax is condensed from the gas. The wax is soluble to the condensate oil. Then they form a transparent colloidal, glassy block material, which has a strong binding effect on the condensate oil.

Crystal structure and formation mechanism of spherical porous hydroxyapatite synthesised in simulated body fluid

ABSTRACTWe synthesized spherical porous hydroxyapatite by a wet method using simulated body fluid and studied its structure. A simulated body fluid with a Ca/P molar ratio of 0.09 was prepared using Dulbecco’s PBS, and spherical porous particles with an average particle size of 13 μm were precipitated therein. All spherical particles were covered with submicron plate-like crystals on the surface. Cross-sectional images showed that pores of submicron to 2 μm in size were present at the centre of the spherical particles. In addition, the plate crystals present on the surface were identified as hydroxyapatite (HAp) with the (002) HAp surface in the longitudinal direction and (100) HAp surface in the width direction, extending in the c-axis direction. Here, we discuss the formation mechanism of the spherical porous HAp.

In\xa0situ strain tuning of the metal-insulator-transition of Ca2RuO4 in angle-resolved photoemission experiments

Pressure plays a key role in the study of quantum materials. Its application in angle resolved photoemission (ARPES) studies, however, has so far been limited. Here, we report the evolution of the k-space electronic structure of bulk Ca2RuO4, lightly doped with Pr, under uniaxial strain. Using ultrathin plate-like crystals, we achieve uniaxial strain levels up to −4.1%, sufficient to suppress the insulating Mott phase and access the previously unexplored electronic structure of the metallic state at low temperature. ARPES experiments performed while tuning the uniaxial strain reveal that metallicity emerges from a marked redistribution of charge within the Ru t2g shell, accompanied by a sudden collapse of the spectral weight in the lower Hubbard band and the emergence of a well-defined Fermi surface which is devoid of pseudogaps. Our results highlight the profound roles of lattice energetics and of the multiorbital nature of Ca2RuO4 in this archetypal Mott transition and open new perspectives for spectroscopic measurements.

Synthesis and oxidation resistance of MoAlB single crystals

Needle and plate like single MoAlB crystals were synthesized by reacting MoB and Al powders. The growth of MoAlB single crystals was promoted by either increasing dwell temperature or by adding excess of Al. When raising the temperature from 1100 to 1300 °C, the shape of MoAlB single crystals transformed from needle to plate like. The single crystals exhibited anisotropic oxidation resistance where the (0l0) plane showed a better oxidation resistance compared to (l00) and (00l) planes. The oxidization weight gain tested at 1100 °C and weight loss at 1300 °C suggests the beneficial role of a dense Al2O3 scale formed on the plate-like single crystals.

Storage stability of bleached rice bran wax organogels and water-in-oil emulsions

In this study, the effects of storage time (90 days) at refrigerated (4 ± 2 °C) and room (30 ± 2 °C) temperatures on the quality of bleached rice bran wax organogels (BRXO) and water-in-oil (W/O) emulsions prepared using organogels (EO) were determined. BRXO was produced by mixing rice bran oil (RO) with bleached rice bran wax (BRX, 9% wax). EO (20% aqueous phase, 80% oil phase) was prepared with BRXO without adding an emulsifier. All quality attributes changed during storage at both temperatures. The colors of BRXO and EO were slightly changed, while those of RO and the emulsion without the addition of organogels (E) were notably changed. EO showed better stability than E. In assessing the various stages of oxidative stability, the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were determined. The PV peaked at 30 days (E and EO) and 90 days (RO and BRXO) and later declined. TBARS values decreased with a decrease in the storage temperature and time. There were no significant changes in the firmness, hardness or stickiness of BRXO and EO at 30 °C during storage (p < 0.05). The polymorphisms of RO appeared to be small, dispersed, plate-like crystals. The BRXO crystal morphology was needle-like and fibrous. All stored samples at both temperatures showed similar morphologies. Regarding EO, the water droplets were dispersed and trapped in the crystal network. Based on the quality parameter results, the bleached rice bran wax can produce stable structured BRXO and W/O emulsions.

Superconductivity in LaPd2Bi2 with CaBe2Ge2-type structure

Here we report the synthesis and superconductivity of a novel ternary compound LaPd2Bi2. Shiny plate-like single crystals of LaPd2Bi2 were first synthesized by high-temperature solution method with PdBi flux. X-ray diffraction analysis indicates that LaPd2Bi2 belongs to the primitive tetragonal CaBe2Ge2-type structure with the space group P4/nmm (No. 129), and the refined lattice parameters are a = 4.717(2) {\AA}, c = 9.957(3) {\AA}. Electrical resistivity and magnetic susceptibility measurements reveal that LaPd2Bi2 undergoes a superconducting transition at 2.83 K and exhibits the characteristics of type-II superconductivity. The discovery of superconductivity in LaPd2Bi2 with CaBe2Ge2-type structure may help to further understand the possible relationship between the occurrence of superconductivity and the crystal structures in 122-type materials.

Crystal Growth and Dissolution Dynamics of l-Phenylalanine Controlled by Solution Surface Laser Trapping

We present sequential behavior of nucleation, growth, and dissolution of an l-phenylalanine plate-like crystal which is induced by a focused continuous-wave near-infrared laser beam in unsaturated solution. Upon the laser irradiation into the air/solution interface, the single crystal is generated from the focus and continuously grows two-dimensionally while being trapped by the laser. The crystal growth is stopped when the laser power is decreased. The crystal size is kept constant for a certain time period, and then the crystal starts dissolution. The dissolution is also induced by moving the crystal from the focus at the air/solution interface. When the crystal is shifted far from the original position where the crystallization is induced, the crystal starts dissolution at a certain distant position. Based on the demonstrations of the crystal size change during the laser manipulation, we conclude that the l-phenylalanine crystal is surrounded by a highly concentrated domain of a few hundreds of micrometers consisting of l-phenylalanine liquid-like clusters.

Bent crystals for efficient beam steering of multi TeV-particle beams

Charged particle beams can be manipulated by exploiting the channeling phenomenon in bent crystals. Two plate-like crystals, bent by mechanical holders, were manufactured and characterised for such purpose at the Sensor and Semiconductor Laboratory in Ferrara, Italy. An anticlastic curvature was obtained for these crystals, achieving a steering angle of the order of 1 mrad, which is about 20 times larger than the values currently achieved for the bent crystals used in the LHC for collimation experiments. Finally, a Geant4 simulation was performed to study the channeling efficiency for beam deflection with 400 GeV/c and 7 TeV/c proton beams. Such crystals represent technological progress in the development of bent crystals for highly energetic charged particle beams. Indeed, they are designed to impart an angular kick to a 7 TeV/c proton beam with unprecedented high efficiency. Therefore, this study demonstrates the possibility of realizing bent crystals suitable for beam extraction in high-energy hadron accelerators, such as LHC or at the future FCC. A further series of studies should be conducted to evaluate the channeling efficiency and the deflection angle of the realized crystals via a charged proton beam.

Microstructural characterization and wear properties of silver and gold nanoparticle doped K-Mg-Al-Si-O-F glass-ceramics

In ascertaining the effects of silver (Ag) and gold (Au) nanoparticles on crystallization of boro-alumino-silicate system; the K2O-MgO-Al2O3-SiO2-B2O3-F glasses doped with/without 0.2 wt% Ag- and Au- content were melt-quenched at 1550 °C. Doping of nanoparticles considerably increased the glass-transition temperature and softening point but decreased the thermal expansion. A sharp crystallization exotherm in differential scanning calorimetry (DSC) is observed at 750 °C ( ± 1 °C) for glass without nanoparticle and that broadened to 800–855 °C when contains nanoparticle. Opaque glass-ceramics were derived from the glasses by controlled heat-treatment at 1050 °C with predominant crystalline phase fluorophlogopite (KMg3AlSi3O10F2) mica. Traces of Ag- and Au- particles were also identified from X-ray diffraction (XRD) technique. The activation energy (Ec) of crystallization (344 ± 17 kJ/mol) is decreased to 233 ( ± 12) and 307 ( ± 15) kJ/mol (Kissinger method) on doping with Ag- and Au- nanoparticles, respectively. Compact microstructure (FESEM) composed of rock like and plate-like mica crystals are developed in base glass-ceramic and that gets restructured to interlocked type morphology in presence of Ag- nanoparticle. Significant microstructural change induced by nanoparticle addition caused the decrease in microhardness (4.31–4.66 GPa) and increase in thermal expansion. Friction and wear testing under reciprocative sliding (using WC-Co ball) exposed that the average coefficient of friction (COF) is 0.60 ± 0.2 for all glass-ceramics at 20 N load and 10 Hz frequency. At a lower load of 5 N, the average COF value is increased from 0.69 to 0.92 on use of Au-nanoparticle. A Similar trend was also observed at 10 N load as COF increased from 0.62 to 0.78.