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Turmeric (Curcuma longa) contains various compounds that potentially improve health. Bisacurone is a turmeric-derived compound but has been less studied compared to other compounds, such as curcumin. In this study, we aimed to evaluate the anti-inflammatory and lipid-lowering effects of bisacurone in high-fat diet (HFD)-fed mice. Mice were fed HFD to induce lipidemia and orally administered bisacurone daily for two weeks. Bisacurone reduced liver weight, serum cholesterol and triglyceride levels, and blood viscosity in mice. Splenocytes from bisacurone-treated mice produced lower levels of the pro-inflammatory cytokines IL-6 and TNF-α upon stimulation with a toll-like receptor (TLR) 4 ligand, lipopolysaccharide (LPS), and TLR1/2 ligand, Pam3CSK4, than those from untreated mice. Bisacurone also inhibited LPS-induced IL-6 and TNF-α production in the murine macrophage cell line, RAW264.7. Western blot analysis revealed that bisacurone inhibited the phosphorylation of IKKα/β and NF-κB p65 subunit, but not of the mitogen-activated protein kinases, p38 kinase and p42/44 kinases, and c-Jun N-terminal kinase in the cells. Collectively, these results suggest that bisacurone has the potential to reduce serum lipid levels and blood viscosity in mice with high-fat diet-induced lipidemia and modulate inflammation via inhibition of NF-κB-mediated pathways.

Lubricant performance can be improved using additives such as organic friction modifiers (OFMs) and is influenced by their conformation and properties in the space confined between the substrate surfaces, rendering the detailed property analysis of confined OFMs and lubricants a matter of high practical significance. To date, studies on fatty acids as confined OFMs have mainly focused on linear- and unsaturated-chain molecules, leaving branched-chain structures underexplored. To bridge this gap, we used resonance shear measurements in this study to probe the viscosity of two branched-chain C

We have successfully performed X-ray diffraction measurements of the liquids octamethylcyclotetrasiloxane (OMCTS, a quasi-spherical-shaped molecule) and

The effect of a substrate on the heterogeneous two-dimensional (2D) nucleation of colloidal crystals has been investigated. Nucleation rates, J, of 2D colloidal crystals on uncoated cover glass, Pt...

The orientational behavior of a smectic-A liquid crystal (4-cyano-4'-octylbiphenyl, 8CB) confined between mica surfaces as well as between silica surfaces with a nanometer scale thickness was investigated by synchrotron X-ray diffraction measurement. The crystallographic axes of two confining mica sheets were adjusted parallel to each other to induce the preferential orientation of 8CB molecules along their crystallographic axis. The silica surfaces, which were hydrophilic and amorphous and had nanometer level smoothness, were prepared on mica surfaces using a sputtering technique. The X-ray diffraction measurement revealed that the 8CB molecules, confined between mica surfaces (DHW = 1.7 nm) and between silica surfaces (DHW = ca. 2 nm), took a planar orientation (oriented its long axis parallel to the surface) and formed a lamellar structure. However, the in-plane orientation of the confined 8CB changed depending on the confining surfaces. The lamellar axis of the 8CB confined between mica surfaces uniaxially oriented most probably due to the preferential alignment of its long axis along the principal crystallographic a-axis of the mica. On the other hand, 8CB between the silica surfaces formed lamellar domains in which the lamellar axis of 8CB omnidirectionally oriented in-plane. The effect of the shear on the orientation of the nano-confined 8CB was also investigated. The lamellar axis, corresponding to the long axis of the 8CB molecules confined between the mica surfaces, rotated only ca. 3 degrees within the plane parallel to the surface by perpendicularly applying shear to the axis. The lamellar axis of the 8CB molecules between the silica surfaces showed no noticeable change by applying the shear. These results indicated that the effect of shear to align the 8CB molecules was significantly suppressed due to the confinement effect which significantly reduces the mobility of molecules as well as the alignment effect along the crystallographic axis in the case of mica. We also observed a change in the orientation of nano-confined 8CB after shear treatment at large D (= 3.3 μm).

X-ray diffraction measurement at the SPring-8 synchrotron was employed to investigate the structures of two types of imidazolium-based ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTF2]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), confined between silica surfaces by varying the surface separation distances of ca. 500 nm (bulk liquid), ca. 10 nm, and ca. 2 nm (hard wall thickness). The obtained diffraction profiles and intensities were discussed by considering the structures and properties of the nano-confined ILs between the silica surfaces investigated by resonance shear measurement (RSM) and molecular dynamics simulation (MD) in our previous reports. [C4mim][NTf2] showed two diffraction peaks at q = 8.8 nm-1 (spacing d = 0.71 nm) and at q = 14.0 nm-1 (spacing d = 0.45 nm) at the greatest distance (D = ca. 500 nm), which were assigned to the interval between the same ions (anion-anion or cation-cation) within the polar network of [C4mim][NTf2] and the interval between the neighboring anion-cation, respectively. The positions of these two peaks remained the same at D = ca. 10 nm and at the hard wall (D = ca. 2 nm) and their intensity factor increased, indicating that both the cation and anion existed in the same layer. This result was consistent with the checkerboard structure of [C4mim][NTf2] on the silica surface computer simulated in our previous studies. On the other hand, [C4mim][BF4] showed a peak at q = 15.4 nm-1 (spacing d = 0.41 nm) corresponding to the anion-cation interval at the greatest distance (D = ca. 500 nm). This peak became broader and weaker at D = ca. 12 nm and at D = ca. 2 nm.

We employed surface forces and resonance shear measurement (RSM) for studying the structure and properties of typical concentrated polymer brushes (CPBs) of poly(methylmethacrylate) (PMMA) in toluene, which are known to show very low friction. The surface forces measured between the silica surfaces bearing PMMA brush layers showed a steric repulsive force at distances between the silica surfaces of less than ca. 1050 nm (Donset). Upon retraction after compression of the PMMA brush layers, no adhesive force was observed. This indicated that the interpenetration of the polymer chain was not induced by the normal load. Based on the resonance shear measurement, the elastic (k2) and damping (viscous) (b2) parameters, which represent the dynamic properties, of the PMMA brush layers were obtained by analyzing the resonance curves. At distances below the Donset, the b2 value significantly increased and slightly decreased at the higher normal loads, and the k2 value monotonically increased with increasing load. These k2 and b2 values were greater than those obtained for a PMMA brush layer and a bare silica surface (PMMA-silica). This indicated that the mobility of the polymer chains for the PMMA-PMMA brush layers was more suppressed compared to that for the PMMA-silica, due to the interpenetration of the polymer chains. The interpenetration of the polymer chains, commonly not observed for CPBs, could be most probably induced by the application of both the normal load and oscillating shear motion. With increasing shear amplitude on the compressed PMMA-PMMA brushes (at L = 0.84, 1.34 and 4.28 mN), the b2 value first increased then decreased whilst the k2 value monotonically decreased. These tendencies can be explained by the change from the sticking condition due to interpenetration (high k2), small sliding under interpenetration (increase in b2, decrease in k2), and then smooth sliding by pulling out of interpenetrated polymer chains (decrease in b2 and k2). The obtained results indicated that the operating conditions are quite important for using polymer brush layers as tribological materials because they can exhibit both a high and low friction depending on the conditions such as the load and shear amplitude.

Resonance shear measurement (RSM), which we developed based on a surface force apparatus, can investigate the structuring, and rheological and tribological properties of confined liquids as a function of the surface separation distance (D) from several μm to zero with a nanometer resolution. Using RSM, we reported that the nanoconfined liquids, including commercial lubricants, exhibited properties quite different from the bulk phase. Mechanical modeling of the resonance system is necessary to quantitatively evaluate the properties of confined liquids and/or sheared interfaces. In this study, we improved the model for RSM as follows: (1) We directly measured the movements of the upper and lower surfaces in addition to the measurement on the movement of the vertical spring to confirm the model, which could be used to estimate the parameters used in the model; (2) we proposed a modified mechanical model which considers the effect of additional motion. This model could fit the resonance curves using a identical apparatus constant for the entire measurement range, while the characteristic values of the confined liquids are the same as those obtained using our previous model, and (3) we calculated the friction (shear) force using the improved model and obtained the characteristic values (viscous and elastic parameters) of the confined liquids. This study afforded the simplicity and reliability of a mechanical model analysis of resonance curves, and the friction force calculation employing the viscous and elastic terms can be useful for studying the mechanism of friction force.

Autonomy and automation of spacecraft operations have been long sought goals to reduce costs and risks. Many different approaches depending on the particular mission's needs and characteristics have been tried and taken. Soil Moisture Active Passive (SMAP) is a science spacecraft mission measuring soil moisture, freeze/thaw and other parameters on a global scale, to support weather forecasting, disaster response and climate research. The spacecraft is fairly conventional and is in a sun synchronous near-polar low Earth orbit. The sole instrument is an L-band passive radiometer; the active radar component is currently inoperative. Automation is a characteristic feature of SMAP flight operations. The project practices “lights-out” operations, where the control room is not staffed, except for occasional real time or contingency activities. Operators nominally work only during regular business hours. Activities are planned and set up on a weekly cadence, and automated processes conduct data processing and commanding. Continuous downlink monitoring is enabled by a sophisticated notification architecture, along with weekly telemetry review by experts. A suite of tools and processes are used to implement the automation. Other tools and resources, while not strictly speaking automation, improve efficiency and reliability, which fundamentally achieve the same benefits as automation. As might be anticipated, there are challenges with a complex ground system that link together many disparate elements. On balance, spacecraft operational costs are estimated to be much lower than if the mission was flown in a conventional manner. In summary, the overwhelming majority of commanding during science phase are performed autonomously, without direct human intervention. A very low command error rate was achieved. It is proposed this concept of operations may serve as a useful model for future missions with similar characteristics.

The stereocomplex formation of poly(l,l-lactide) (PLLA) and poly(d,d-lactide) (PDLA) was selected in order to investigate the interaction of the two surfaces including hydrogen bonding and van der Waals interaction. Adhesion force measurement using surface force apparatus (SFA) equipped with an optical microscope was conducted on the PLLA and PDLA spin-coated films. The adhesion forces, Fad, phenomenologically followed the linear relation with the applied normal load, L. For the force Fad between PLLA and PDLA films with low molecular weights (PLLA, Mn = 2800; PDLA, : Mn = 2100), the slope of linear fitting of Fad vs L was significantly larger for the heterointerface (PLLA/PLDA) compared with that for the homointerface (PLLA/PLLA and PDLA/PDLA). However, when polymers with higher molecular weights (PLLA, Mn = 8500; PDLA, Mn = 8300) were measured, the slopes of linear fitting lines were almost the same for hetero- and homointerfaces. This indicated that the mobility of the lower molecular weight PLLA/PDLA films promoted the selective interaction of PLLA and PDLA under the applied normal loads. The adhesion between the outermost PLLA layer and PDLA layer prepared by layer-by-layer (LbL) assembly was also measured. It is interesting that the adhesion force was very weak in this case. This weak adhesion could be explained by the much less mobility of the polymer chain due to the stereocomplex formation within the LbL layers. This study demonstrated that the adhesion force due to the selective interaction of PLLA and PDLA between PLLA/PDLA films could be directly measured, and depended on the mobility of the outermost polymer chains, which reflected the different structures of polymer chains in the organized complex films.

We used molecular dynamics simulations to investigate the effect of disorder of the hydroxylated amorphous silica surface on the structure of 8 nm IL films formed from two ionic liquids featuring the same cation 1-butyl-3-methyl-imidazolium or [BMIM], paired with bis(trifluoromethanesulphonyl)amide [NTF2] and tetrafluoroborate [BF4] anions. Several silica surfaces were modelled to estimate the effect of their atomic-scale configuration on the solid-liquid interface and the results are compared to those simulated on the crystalline cristobalite surface. Using strongly polar surfaces, we could also evaluate the response of the ILs to the electric field externally controlled or generated by charged defects in the silica film. We found that the structure of the liquids becomes weaker away from the interface and more susceptible to electric field. Our simulations show that [BMIM][BF4] has a large intrinsic dipole originating at the interface, resilient to external fields, while the polarisation of [BMIM][NTF2] can be more easily controlled.

The friction between an elastomer and a hard surface typically has two contributors, i.e., the interfacial and deformation components. The friction of viscoelastic hydrogel materials has been extensively studied between planar gel and planar substrate surfaces from the viewpoint of an interfacial interaction. However, the geometry of the contact in practical applications is much more complex. The contribution of geometric and elastic deformation terms of a gel to friction could not be neglected. In this study, we used resonance shear measurements (RSMs) for characterizing the shear response of a glass sphere on a flat polymer hydrogel, a double network (DN) gel of 2-acrylamide-2-methylpropanesulfonic acid and N,N-dimethylacrylamide. The contact mechanics conformed to the Johnson-Kendall-Roberts theory. The observed resonance curves exhibited rather sharp peaks when the DN gel and the silica sphere were brought into contact, and their intensity and frequency increased with the increase in the normal load. We proposed a simple physical model of the shearing system, and the elastic (k2) and viscous (b2) parameters of the interface between a silica sphere and a flat DN gel were obtained. The friction force from elastic deformation and viscous dissipation terms was then estimated using the obtained parameters. It was revealed that the elastic parameter (k2) increased up to 1780 N m(-1) at a normal load of 524 mN, while the viscous parameter (b2) was zero or quite low (0.1 N s m(-1)) for a silica sphere (radius of 18.4 mm). Thus, the friction force between a flat DN gel and a silica sphere in air was dominated by the elastic term due to the local deformation by contact with the silica sphere. By adding water, the elastic parameter (k2) remained the same, while the viscous parameter (b2) slightly increased. However, the viscous term fviscous was still much smaller than felastic. To the best of our knowledge, this study was the first quantitative estimation of the contribution of the elastic deformation term to the friction in the case when deformation of non-flat contact regions occurs. The obtained results can be basic knowledge for designing gels for applications such as artificial cartilages and sliding bearings.

A surface forces apparatus (SFA) measures the forces between two surfaces as a function of the surface separation distance. It is regarded as an essential tool for studying the interactions between two surfaces. However, sample surfaces used for the conventional SFA measurements have been mostly limited to thin (ca. 2-3 μm) micas, which are coated with silver layers (ca. 50 nm) on their back, due to the requirement of the distance determination by transmission mode optical interferometry called FECO (fringes of equal chromatic order). The FECO method has the advantage of determining the absolute distance, so it should be important to increase the availability of samples other than mica, which is chemically nonreactive and also requires significant efforts for cleaving. Recently, silica sheets have been occasionally used in place of mica, which increases the possibility of surface modification. However, in this case, the silver layer side of the sheet is glued on a cylindrical quartz disc using epoxy resin, which is not stable in organic solvents and can be easily swollen or dissolved. The preparation of substrates more stable under severe conditions, such as in organic solvents, is necessary for extending application of the measurement. In this study, we report an easy method for preparing stable silica layers of ca. 2 μm in thickness deposited on gold layers (41 nm)/silica discs by sputtering, then annealed to enhance the stability. The obtained silica layers were stable and showed no swelling in organic solvents such as ethanol and toluene.

We performed the resonance shear measurement (RSM) for evaluating the nanorheological and tribological properties of model lubricants, hexadecane and poly(α-olefin) (PAO), confined between iron surfaces. The twin-path surface forces apparatus (SFA) was used for determining the distance between the surfaces. The obtained resonance curves for the confined lubricants showed that the viscosity of the confined hexadecane and PAO increased due to liquid structuring when the surface separation (D) decreased to a value less than 24 and 20 nm, respectively. It was also determined that the iron surfaces were lubricated by the hexadecane when normal load (L) was less than 1.1 mN, while the confined hexadecane behaved almost solid-like and showed poor lubricity when L was greater than 1.1 mN. In contrast, PAO between the iron surfaces showed high lubricity even under the high load (L2 mN). The surface separation of hexadecane and PAO at a hard wall contact between the iron surfaces was determined to be 4.6 ± 0.5 and 5.0 ± 0.4 nm by applying the fringes of equal chromatic order (FECO) for half-transparent iron films deposited on mica surfaces as substrates. We also characterized hexadecane and PAO confined between mica surfaces for studying the effect of substrates on the confined lubricants.

The normal forces between mica surfaces confining dispersions of ceria (CeO 2 ) nanoparticles in decalin were measured using the surface forces apparatus. The nanoparticles (size ca. 6 nm), synthesized under supercritical conditions in a cubic shape, were coated with decanoic acid. A repulsion force appeared at a distance of 50–80 nm for the first compression, whereas the range was reduced in the subsequent approaches. This indicated that the nanoparticles were rearranged on the mica surface by compression from a disordered initial adsorption pattern. Resonance shear measurements were applied for the first time to a nanoparticle dispersion. The confined particle layers were shown to significantly reduce the friction compared to the mica–mica contact. Those results should contribute to the understanding of the assembly of nanoparticles into thin films under confinement and to the implementation of nanomaterials in tribological applications.

The tribological properties of four phenyl ether lubricants, monoalkydiphenyl ether (MADE), dialkyldiphenyl ether (DADE), m-phenoxyphenoxy m-biphenyl (m-4P2E), and m-bis(m-phenoxyphenoxy) benzene (m-5P4E), confined between mica surfaces have been investigated using the resonance shear measurement (RSM). The RSM study revealed that the viscous parameter of these lubricants increased when they were confined in a nano-space. The viscous parameter b 2 values of these lubricants confined in a gap smaller than ca. 2–3 nm were in the order of MADE > DADE > m-4P2E ≈ m-5P4E, while their bulk viscosities were in the order of m-5P4E > m-4P2E > DADE > MADE. Further, the MADE, which has better hydrodynamic lubrication property because of the lowest bulk viscosity, was relatively easily squeezed out from the gap compared to others. These results have demonstrated that phenyl ether lubricants confined in a nano-space behave quite differently from those of the bulk phase, and the direct characterization of confined lubricants is imperative for designing efficient lubricants, especially for boundary lubrication.

We report the effect of confinement on the electric field induced orientation of a nematic liquid crystal, 4-cyano-4'-hexylbiphenyl (6CB), between mica surfaces. The resonance shear measurement was employed for monitoring changes in the viscosity of 6CB at various surface separation distances (D) with and without an applied electric field. The viscosity depended on the surface separations, and the behaviour for Dca. 20 nm was quite different from that at Dca. 20 nm. For Dca. 20 nm, the viscosity values obtained in the presence of the electric field (ac 1 kHz, 1.87 kV mm(-1), homeotropic orientation) were ca. 2 times higher than the values obtained without the electric field (0 kV mm(-1), planar orientation) due to the difference in the molecular orientation, and were nearly constant. At Dca. 20 nm, the viscosity of 6CB both with and without the electric field sharply increased and they merged into an identical value at D = 12.5 ± 1.3 nm (Dc), then exhibited a plateau up to D = 6 nm. With the decreasing distance below 6 nm, the viscosity of confined 6CB both with and without the electric field further increased up to more than 100 N s m(-1) at the hard wall thickness of D = ca. 4.0 nm. These results indicated that 6CB molecules both with and without the electric field had the same orientation at DDc. The most likely orientation of 6CB was parallel to the surfaces because 6CB was originally in a planar orientation on the mica surface. These results demonstrated for the first time that the effect of confinement exceeded the electric field, thus 6CB molecules could not change their orientation under the electric field at the surface separation below Dc.

We performed the resonance shear measurement (RSM) for evaluating the properties of water confined between silica surfaces with and without water vapor plasma treatment, which was used to increase the density of the silanol groups on the surfaces. We compared the properties of the confined water, such as viscosity and lubricity, by controlling the surface separation at a 0.1 nm resolution. The observed resonance curves for water between the plasma-treated and untreated silica surfaces showed the following results: (1) The viscosity of the water confined between the plasma-treated silica surfaces increased due to water structuring at separations less than 3 nm, while the value for the water between the untreated silica surfaces was 8 nm. (2) The water confined between the plasma-treated surfaces could maintain lubricity under the normal pressure of more than 1.7 MPa; however, the water confined between the untreated surfaces lost lubricity under the normal pressure of more than 0.4 MPa. To discuss these pr...

Optically active ethynylhelicene pentamers and hexamers linked by disulfide bonds were synthesized. They formed self-assembled monolayers (SAMs) with double helix structure on gold surfaces, which were analyzed by infrared reflection-absorption spectroscopy (IR-RAS), quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and circular dichroism (CD). Double helix SAMs could be formed on gold surfaces either from double helices or random coils in solution. The double helices on the surface were more stable than in solution. This result suggested the presence of strong intercomplex interactions between double helix complexes on the surface.

異種材料の接合・接着特性を制御する要因を解明できれば，複合材料の高性能化，高機能化にむけて，具体的な設計指針を与えると期待される。本研究では表面力装置による接着力の精密測定と光学顕微鏡による接着面の同時観察により，三種類のNiCr膜（Ni100，Ni90Cr10，Ni60Cr40）とポリイミドフィルム間の接着を空気中への露出時間を変えて評価した。NiCr表面を空気中に露出後1時間以内の接着力の大きさはNi90Cr10＞Ni60Cr40＞Ni100となったが，Crを含む表面の接着力は露出時間にともない減少し，20時間後ではNi100＞Ni90Cr10≒Ni60Cr40となった。一方，窒素雰囲気中では接着力の経時変化が抑制された。従来報告されているようにCrはポリイミドとの接着力の増加に寄与することが確認され，また空気中では容易に酸化されるため露出時間増加にともない接着力は減少することがわかった。

界面の水は生体を代表例とする様々な機能表面で重要な役割を担っており，分子レベルでの現象の理解が必要不可欠である．表面力測定は，得られる相互作用ポテンシャル（表面力曲線）に，固－液界面からバルクへの特性変化が反映されるために，固－液界面の特性評価に有用である．本稿では，表面力測定とその発展形として著者らが開発した共振ずり測定を用いて界面の水を対象とした二つの最近の研究展開，（1）雲母間に閉じ込められた水の特性評価，（2）水の界面マクロクラスターの状態評価，について解説する．

Rheological and tribological properties of a model lubricant consisting of a two-component liquid crystal, mixtures of Sudan Black B (dye) and 4-cyano-4'-hexylbiphenyl (6CB, liquid crystal), nano-films confined between mica surfaces were studied as functions of the surface separation distance (D) and the normal load (N). The compositions of Sudan Black B/6CB binary system were determined by FECO spectroscopy. The rheological properties which reflects the structuring and packing of binary system were examined employing the resonance shear measurement with varying the separation distance at the nanometer resolution. FECO spectroscopy revealed that apparent extinction coefficient of Sudan Black B/6CB increased monotonically with decreasing D, especially below ca. 6 nm, at all initial dye concentrations studied, 0.06-1.03 wt%. This indicated the increase in the Sudan Black B concentration in the gap between mica surfaces with the decreasing D, due to the interaction of a large planar structure dye, Sudan Black B, with mica surface. The resonance shear measurement revealed the sudden drop of the amplitude during the shear, which was not observed for one component 6CB. This drop corresponded to the stick-slip transition, which reflected the structural change in the confined dye/liquid crystal from the solid-like to liquid-like state. The combination of FECO spectroscopy and resonance shear measurement can give insights into the properties of multi-component mixtures depending on their composition.

A new method for preparing poly(acrylic acid) (PAA) films on silicon oxide surfaces with smooth morphology has been developed. Acrylic acid (AA) was preferably adsorbed on silicon oxide surfaces in AA/ chloroform binary liquids and formed a hydrogen-bonded organized structure, which was called molecular macrocluster. AA macroclusters on silicon oxide surfaces were in-situ polymerized to obtain molecularly flat polymer films with thickness up to 10 nm. In-situ polymerizations were conducted by photo-irradiation in the presence of a photo initiator, 2,2-dimethoxy-2-phenyl-acetophenone (DPA). As a reference, the adsorption of PAA polymerized in the bulk solution was examined on silicon oxide surfaces. A series of techniques such as attenuated total reflection-FTIR (ATR-FTIR) spectroscopy, ellipsometry and atomic force microscopy (AFM) was utilized for characterizing two types of films. It was found that flat PAA films with linear hydrogen-bonded COOH could only be obtained by in-situ polymerization, which demonstrated this method was an effective way for preparing molecularly uniform polymer films. The surface morphology and thickness of obtained PAA films were found to be dependent on the monomer concentration, initiator amount and photoirradiation time. Molecularly uniform and flat PAA films were obtained after 5 min irradiation at 0.8 mol% AA in the presence of 5 wt% DPA.

To evaluate the friction properties of new lubrication systems, two types of ammonium-based ionic liquids (ILs), N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate ([DEME][BF4]) and N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide ([DEME][TFSI]), were investigated by resonance shear measurements (RSM) and reciprocating type tribotests between silica (glass) surfaces. RSM revealed that an IL layer of ca. 2 nm in thickness was maintained between the silica surfaces under an applied load of 0.40 mN ∼ 1.2 mN. The relative intensity of the RMS signal indicated that the friction of the system was lower for [DEME][BF4], 0.12, than that of [DEME][TFSI], 0.18. On the other hand, the friction coefficients μk obtained from the tribotests of [DEME][BF4] were lower than that of [DEME][TFSI] for sliding velocities in the range of 5.0 × 10(-4) m s(-1) to 3.0 × 10(-2) m s(-1) under applied loads of 196-980 mN. The friction coefficients obtained by the tribotest are discussed with reference to the RSM results.

Recently, we have found that alcohols adsorbed on the silica surface in non-polar liquids (cyclohexane, etc.) form ordered structures extending to several tens of nanometer through hydrogen bonding between the surface silanol groups and the adsorbed alcohols as well as between the adsorbed alcohols. We call this structure the surface molecular macrocluster. Surface forces measurement has revealed that the long range attraction appears from distances about twice of the macrocluster layer thickness. The bridging of the adsorption layers brings about the long range attraction due to the interfacial energy between the adsorption layer of molecular macroclusters and the bulk solution. In this study, the interfacial energies (γ) between the methanol adsorption layer and the bulk solution were evaluated by analyzing the long range attraction as well as pull-off force in methanol-cyclohexane binary liquid mixtures. The interfacial energy (γ) was evaluated to be 7.2 ± 0.3 mN/m, which was more than 10 times larger than that for methanol/cyclohexane interface at the phase separation (0.6 mN/m). This larger interfacial energy should be caused by the rather fixed orientation of methanol molecules at the interface due to the ordered structure of methanol molecules in a macrocluster. [DOI: 10.1380/ejssnt.2006.244]

The NASA Dawn spacecraft mission is studying conditions and processes of the solar system's earliest epoch by investigating two protoplanets remaining intact since their formations, Ceres and Vesta. Launch was in 2007. Ion propulsion is used to fly to and enter orbit around Vesta, depart Vesta and fly to Ceres, and enter orbit around Ceres. A conventional blowdown hydrazine reaction control system (RCS) is used to provide external torques for attitude control. Reaction wheel assemblies were intended to provide attitude control in most cases. However, the spacecraft experienced one, then two apparent failures of reaction wheels. Also, similar thrusters experienced degradation in a long life application on another spacecraft. Those factors led to RCS being operated in ways completely different than anticipated prior to launch. Numerous mitigations and developments needed to be implemented. The Vesta mission was fully successful. Even with the compromises necessary due to those anomalies, the Ceres mission is also projected to be feasible.

We used molecular dynamics simulations to study the structure and shear dynamics of two ionic liquids (ILs) featuring the same cation 1-butyl-3-methyl-imidazolium or [BMIM], paired with bis(trifluoromethanesulphonyl)amide [NTF2] and tetrafluoroborate [BF4] anions, confined between two hydroxylated silica surfaces. The results demonstrate how the shape of IL molecules affects their layering structure at hydroxylated silica surfaces and how the layered structure of nanoconfined liquids determines their dynamical properties at the molecular level. When [BMIM][NTF2] is sheared, larger molecular fluctuations in the inner layers are required to stabilise the system, and the resulting dynamics is irregular. The alternating charged layers in [BMIM][BF4] allow the system to stabilise through smaller oscillations, and the layers appear to shear on top of each other in a laminar fashion. The simulated dynamics explains qualitatively the relative change in viscosity that the two ILs exhibit when confined, as has been observed in previous experiments.

The macrocluster formation of propionic acid adsorbed onto silica (glass and silicon oxide) surfaces from propionic acid-cyclohexane mixtures has been studied using surface forces measurement, adsorption excess isotherm measurement and Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflection (ATR) and the transmission (TS) mode. In pure cyclohexane, the interaction extended to only 2-3nm and described as the van der Waals force. On the other hand, unusually long-range attraction was observed in the presence of propionic acid in the concentration range of 0.1-20mol%. At 0.5mol% propionic acid, the attraction appeared at 67±8nm and turned into repulsion below 2nm upon compression. This attraction was accounted for in terms of the bridging of opposed adsorption layers of propionic acid on the surfaces. The thickness of the adsorption layer was estimated as half of the attraction range to be 34±4nm for 0.2-1.0mol% propionic acid, which agreed well with the thickness calculated from the adsorption excess amount of propionic acid, 38±9nm, assuming that the adsorption layer consisted of pure propionic acid. Chemical interactions involved in the formation of the adsorption layers of propionic acid were investigated by FTIR-ATR spectroscopy using silicon oxide as a substrate. The hydrogen-bonded OH absorption of propionic acid around 3120cm-1 was observed at 0.1mol% propionic acid where the contribution from the bulk solution was small. The linear structure of the surface cluster initiated from the surface silanol groups was demonstrated from the peak position and the dichroic analysis of the hydrogen-bonded OH absorption. An application of this phenomenon with respect to the nano-scale coating technique was demonstrated by the photo-polymerization of the acrylic acid monomer adsorbed on the silica surfaces. Photo-irradiation of the silica substrates for 20min in 0.1mol% acrylic acid produced extremely uniform and flat polymer films with a thickness of≈25nm, which exhibited an average difference in the height of less than 0.2 nm for a 3μm×3μm area on the surface.

We investigated interfacial water, formed by adsorption or phase separation (prewetting transition), on a silica surface in water-cyclohexane binary liquids using a combination of colloidal probe atomic force microscopy (AFM) and sum frequency generation (SFG) vibrational spectroscopy. At 33 ± 9 ppm water, the long-range attraction extending to 19.4 ± 2.9 nm appeared, which was caused by the contact of water layers formed on silica surfaces. The attraction range increased with increasing water concentration and reached 97 ± 17 nm at the saturation concentration of water in cyclohexane (C*), indicating that the thickness of the water layer formed on silica was ca. 50 nm. The interfacial energy between the water adsorption layer and bulk solution (γ = 79.3 ± 2.0 mN/m) was estimated from the pull-off force, and was significantly larger than the value for the bulk water/cyclohexane interface (γ = 50.1 mN/m). SFG spectroscopy demonstrated that the interfacial water formed an icelike structure at C*. These results indicated that the interfacial water molecules formed an icelike ordered structure induced by the hydrogen bonding with surface silanol groups, resulting in the free OH groups being more exposed to the bulk solution. On the other hand, the water adsorption layer induced by phase separation at water concentrations above C* was found to be less ordered and its structure at the adsorption layer/bulk interface was almost the same as that of bulk water, although its thickness was almost the same as that formed at C*. To our knowledge, this is the first report of the observation of liquid adsorption layers formed by chemical interaction up to saturation and by the wetting transition above saturation, and their differences in the structure and properties at the molecular level.

The Mars Science Laboratory (MSL) is NASA's next major mission to Mars, to be launched in September 2009. It is a nuclear powered rover designed for a long duration mission, with an extensive suite of science instruments. The descent and landing uses a unique 'skycrane' concept, where a rocket-powered descent stage decelerates the vehicle, hovers over the ground, lowers the rover to the ground on a bridle, then flies a safe distance away for disposal. This descent stage uses a regulated hydrazine propulsion system. Performance requirements for the pressure regulator were very demanding, with a wide range of flow rates and tight regulated pressure band. These indicated that a piloted regulator would be needed, which are notoriously complex, and time available for development was short. Coincidentally, it was found that the helium regulator used in the Space Shuttle Orbiter main propulsion system came very close to meeting MSL requirements. However, the type was out of production, and fabricating new units would incur long lead times and technical risk. Therefore, the Space Shuttle program graciously furnished three units for use by MSL. Minor modifications were made, and the units were carefully tuned to MSL requirements. Some of the personnel involved had built and tested the original shuttle units. Delta qualification for MSL application was successfully conducted on one of the units. A pyrovalve slam start and shock test was conducted. Dynamic performance analyses for the new application were conducted, using sophisticated tools developed for Shuttle. Because the MSL regulator is a refurbished Shuttle flight regulator, it will be the only part of MSL which has physically already been in space.

This paper describes a new physical model for resonance shear measurement. The resonance shear method developed by us provides a tool for investigating the rheological and tribological properties of liquids confined between two surfaces as a function of the surface distance from micrometer to zero (contact) with nanometer level resolution with high sensitivity and stability. The properties of the confined liquid can be quantitatively studied by analyzing the resonance curve using a physical model. However, the quantitative analysis using the previously developed model was applicable only for the condition of the relatively low liquid viscosity (below approximately 100 Pa s). A new physical model described in this paper enabled us to continuously analyze the properties of confined liquids at all distances, which was not possible by the previous model. It became possible to calculate the movement of a lower surface and the shear rate applied on the confined sample using the parameters obtained from the resonance curves.

We designed a new surface forces apparatus for measuring the interactions between two nontransparent substrates and/or in nontransparent liquids. The small displacement of a surface, the bottom one in this study, was measured by the two-beam (twin path) interferometry technique using the phase difference between the laser light reflected by the fixed mirror and that by the mirror on the back of the bottom surface unit. It is possible to determine the distance with a resolution of 1 nm in the working range of 5 microm. This apparatus was successfully applied to measure the forces between mica surfaces in pure water and aqueous KBr solutions.

Adsorption of ethanol onto silica surfaces from ethanolcyclohexane binary liquids was investigated by a combination of colloidal probe atomic force microscopy and Fourier transform IR spectroscopy using the attenuated total reflection (ATR) mode. An unusually long range attraction was found between the silica surfaces in the presence of ethanol in the concentration range of 0.1-1.4 mol%. At 0.1 mol% ethanol, the attraction appeared at a distance of 35 ±3 nm and turned into a repulsive force below 3.5 ± 1.5 nm upon compression. The ATR spectra demonstrated that ethanol adsorbed on the surfaces formed hydrogen-bonded clusters even in a low ethanol concentration range of 0.1–0.5 mol%, where the attractions were especially long-ranged and practically no ethanol cluster formed in the bulk solutions. The spectra also indicated that the cluster formation involved hydrogen-bonding interactions between surface silanol groups and ethanol hydroxyl groups in addition to those between ethanol molecules. We account for the observed longrange attraction by the bridging of opposed adsorption layers of ethanol on the silica surfaces.

Recently, we have succeeded in identifying the structure of the adsorption layer of ethanol on a silica surface in cyclohexane to be a hydrogen-bonded linear aggregate (polymer), which we call a surface molecular macrocluster. In this work, we studied the effect of the miscibility of liquids on the formation of the surface molecular macroclusters for confirming that this is a surface induced phenomenon. We investigated the interaction and the structure of methanol adsorbed on a silica surface in methanol-cyclohexane binary liquids by a combination of colloidal probe atomic force microscopy, adsorption excess isotherm measurement, and FTIR spectroscopy using the attenuated total reflection (ATR) mode, and compared the results with those of the ethanol-cyclohexane and 1-propanol-cyclohexane binary liquids. The former system is immiscible at methanol concentrations of ca. 8-90 mol %, and the latter two are miscible at any composition. At 0.03 mol % methanol, which is far from the critical concentration for the phase separation, the contact of the methanol macrocluster layers formed on the silica surface brought about the attraction from a distance of 42 +/- 5 nm which was similar to that observed in ethanol-cyclohexane. At a methanol concentration of 9.0 mol %, above bulk phase separation, completely different force profiles were observed. These results demonstrated that the molecular macrocluster formation was different from the wetting induced by the bulk.