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This study investigates the effects of both, molecular structure and surface roughness, on the tribochemical decomposition of synthetic base oils under high-vacuum conditions. Nascent steel surfaces exhibit high activity to catalyze the decomposition of synthetic oil under lubricating conditions. Decomposition was performed on multiply alkylated cyclopentane (MAC) and alkyl diphenyl ether (ADE) at the nascent surface of bearing steel 52100 and was monitored by a ball-on-disk friction tester in a vacuum chamber attached to a quadrupole mass spectrometer. Although MAC decomposed, ADE did not decompose on the flat steel surface. Steel surfaces used within this experiment underwent procedural abrasion, providing the requisite roughness to generate the nascent steel surface for the friction test. Decomposition of ADE and desorption of benzene were observed in the presence of the nascent steel surface under friction. As the surface morphology of the pretreated roughened surfaces changed during friction, the contact pressure and plasticity of the surface decreased. We concluded that the tribochemical decomposition of ADE was accelerated on rough steel surfaces by the generation of a nascent surface at the point of metal-metal contact. From these results, the critical role of a nascent steel surface on the tribochemical decomposition of syntheticoils is discussed.

Recent approaches have begun to identify common variance across co-occurring childhood adversities (CAs) and their associations with symptoms of psychopathology. However, few studies have investigated these questions in high-risk samples, and in different cultural contexts. This study examined common variance amongst 18 types of CAs and associated symptomatology in 457 children and adolescents living in 24 residential homes in Japan. Principal component analysis identified four significant components that explained 35.1% of the variance: parental abuse, parental psychosocial risks, parental absence, and parental neglect. Path analysis revealed general as well as differential associations with negative outcomes: parental abuse, parental neglect, and parental psychosocial risks significantly associated with conduct problems, whereas parental abuse uniquely associated with peer problems, and parental neglect with hyperactivity/inattention. As well as confirming prior knowledge, these findings also extended understanding of these associations to a new cultural context. Future studies should take into account the multidimensional nature when assessing CAs. Electronic supplementary material The online version of this article (10.1007/s10578-018-0850-4) contains supplementary material, which is available to authorized users.

The author attempts to understand the kamikaze attacks during World War II as a phenomenon that crossed a border into the systemic use of suicide attacks. The author first presents two historical precursors before World War II: the Seinan (Southwest) War in 1877; and an event in 1932 known as the Three Suicide-Bombing Heroes. To examine the process leading to kamikaze, the author offers two examples: a scene in which a suicide attack was proposed to pilots; and a story of a general, Ōnishi, who has been identified as a person responsible for the campaign. In the discussion, the author employs psychoanalytic arguments on chosen trauma and apocalyptic order to see kamikaze as sharing a common psychology with other warfare. He then focuses on the previous debate over the normality of suicide attackers and argues for the importance of finding a role for positive value in the psychological processes. He concludes that kamikaze was realized through multiple mechanisms and ended up crossing the border to...

Molecular alignment is key to achieving an ultra-low friction coefficient. We prepared associated carboxylic acids using oleic acid and p-pentylbenzoic acid via hydrogen bonding, involving a benzene ring and an eight-membered cyclic carboxylic acid in the molecules. We investigated frictional properties when these were added into a base oil and found that the associated carboxylic acids decreased the traction coefficient in EHL and boundary lubrication, although the viscosity increased. An in situ micro Fourier transform infrared spectroscope showed that both the eight-membered cyclic carboxylic acid and the benzene ring were oriented parallel to the shearing force, leading to the low friction coefficient.

Triboemission of hydrocarbon molecules such as methane and ethylene induces chemical and mechanical wear of diamond-like carbon., Understanding atomic-scale wear is crucial to avoid device failure. Atomic-scale wear differs from macroscale wear because chemical reactions and interactions at the friction interface are dominant in atomic-scale tribological behaviors, instead of macroscale properties, such as material strength and hardness. It is particularly challenging to reveal interfacial reactions and atomic-scale wear mechanisms. Here, our operando friction experiments with hydrogenated diamond-like carbon (DLC) in vacuum demonstrate the triboemission of various hydrocarbon molecules from the DLC friction interface, indicating its atomic-scale chemical wear. Furthermore, our reactive molecular dynamics simulations reveal that this triboemission of hydrocarbon molecules induces the atomic-scale mechanical wear of DLC. As the hydrogen concentration in hydrogenated DLC increases, the chemical wear increases while mechanical wear decreases, indicating an opposite effect of hydrogen concentration on chemical and mechanical wear. Consequently, the total wear shows a concave hydrogen concentration dependence, with an optimal hydrogen concentration for wear reduction of around 20%.

Tribological properties closely depend on the structures of lubricating films between moving surfaces. Lubricating films are formed at lubricating contacts under dynamic conditions, including high temperature, high pressure and high shearing. Thus, structures of lubricating films are greatly affected by the conditions of the environment. In situ observation of lubricating films by micro-FTIR is described in order to characterize the film components and structure formed from lubricants under dynamic conditions.

Single-molecule fluorescence measurements of biological samples frequently suffer from background autofluorescence originating from fluorescent materials pre-existing in living samples, and from unstable photo-physical properties of fluorescent labeling molecules. In this study, we first describe our method of selective imaging of nanodiamonds containing nitrogen-vacancy centers, promising fluorescent color centers, by a combination of optically detected magnetic resonance. The resultant images exhibit perfect elimination of extraneous fluorescence in real-time microscope observations. As the practical example applied to an in vivo system, we measured the resonance spectrum of nanodiamonds introduced into the intestine of Caenorhabditis elegans in the clear background and compared the spectral profile over time. The observed evolution strongly suggests that the rotation of the nanodiamond was detected. We also report our recent progress in the development of a spectrometer equipped with an avalanche photo-diode for fast sampling of photons, which can be used while observing the selective image of a field of view in a real-time manner. This apparatus is suitable for exploring dynamics through the measurement of fluctuation in fluorescence intensity caused by a rotating nanodiamond.

The correlation between molecular interaction and traction properties was investigated using a traction tester and in situ observation of elastohydrodynamic lubrication film with a micro-Fourier transform infrared spectrometer. The sample oils used were polypropylene glycols (PPGs) with the end-group of alcohol or ether and a synthetic hydrocarbon oil, poly-α-olefin. From the traction tests, it was found that the traction coefficient of PPG was sensitive to the end-group. PPG with alcohol as the end-group showed a higher traction coefficient than that with the ether group. In situ observation with a micro-Fourier transform infrared was performed in order to investigate the molecular interaction of the lubricant oil. It was found that the hydrogen bonding of hydroxyl groups in PPG was strengthened by high pressure in the Hertzian contact region. These results suggest that the rheological properties in the elastohydrodynamic lubrication contact region were affected by the strengthened hydrogen bonding. Copyright © 2014 John Wiley & Sons, Ltd.

We previously reported some findings on the applicability of porous Ni materials to the electrodes of electric double layer capacitors (EDLCs) [1] . It was found that the porous Ni material prepared via alkali-leaching of Ni–Al alloys and dry process without heating and air-contact provides pseudocapacitance as well as electric double-layer (EDL) capacitance in organic electrolyte solution, TEA·BF4/PC. The pseudocapacitance is ascribed to the electrochemically active surface and bulk state of the porous Ni with low crystallinity. In TEA·BF4/PC, porous Ni materials were found to provide lower volumetric total capacitance than the values of the commercial activated carbons, due to the large difference of specific surface areas (i.e., porous Ni: 43 m2/g, the activated carbons examined: 1508–2164 m2/g). However, a significant point was the high value of EDL capacitance normalized by the surface areas (CSA), i.e., 10.2 μF/cm2, which was beyond 3.6–6.6 μF/cm2 of the activated carbons. In this study, the volumetric total capacitance and CSA of porous Ni materials have been further enhanced by using ionic liquids as electrolytes. The volumetric total capacitance has reached 67.4 F/cm3 (three-electrode evaluation) in EMIm·BF4 ionic liquid, which approaches 79.3 F/cm3 of a high-capacitance-type activated carbon, MSP-20. The total capacitance is affected by the class of ionic liquids due to the difference of the viscosity and conductivity, whereas the pure EDL capacitance is dependent on the ion sizes rather than the physical properties of ionic liquids. Furthermore, the difference of either anions or cations affects the capacitive behaviors in both positive and negative electrodes. Significantly, the CSA value of porous Ni electrodes has increased from 10.2 μF/cm2 in TEA·BF4/PC to 16.6 μF/cm2 in EMIm·BF4, which is much higher than 7.0 μF/cm2 of MSP-20. Furthermore, the electrochemical stabilization of porous Ni materials has been achieved by heat treatment under vacuum, resulting in an excellent cycle performance caused by the exclusion of pseudocapacitance. More noteworthy is that the high CSA can be retained even after the stabilization. The results of this study further emphasize the potential of porous Ni materials as EDLC electrodes.

In this work, we have investigated the infrared spectra of polar lubricant in order to explore the molecular interaction under high pressure and temperature conditions using diamond anvil cell. Polypropylene glycol and oleic acid were used as base oil and additive, respectively. Stretching vibration mode of polar functional groups, such as νO–H and νC═O, was found to be sensitive to pressure and temperature. The peak positions of the vibration mode were shifted clearly to lower wavenumber as pressure increases, and temperature increase induced a slight shift to higher wavenumber. These results indicate that hydrogen bonding between lubricant molecules of base oil and additive was influenced by pressure and temperature. And furthermore, the dependency of the peak shift was discontinuous and affected mainly by pressure. These results imply a structural change on the basis of the molecular interaction of the lubricating molecules at elastohydrodynamic lubrication contacts. Copyright © 2013 John Wiley & Sons, Ltd.

Die Etablierung der Psychoanalyse in Japan war eine Konsequenz aus der Offnung des Landes gegenuber dem Einfluss des Westens durch die Meiji-Restitution von 1868. Dadurch fand westliches psychologisches Denken auch in Japan Verbreitung. Auf dieser Basis entwickelte die Psychoanalyse sich durch personliche Erfahrungen und Kontakte Einzelner. Sie fand in die Kreise von Intellektuellen Eingang und etablierte sich schlieslich in der Psychiatrie. Mit der Grundung von zwei psychoanalytischen Gesellschaften, eine fur Analytiker und eine, in die auch Laien Zugang hatten, fand sie eine eigenwillige Organisationsstruktur.

We examined the effects of ZSTK474, a phosphatidylinositol 3-kinase (PI3K) inhibitor, on adjuvant-induced arthritis (AIA).AIA was induced in Lewis rats by subcutaneous administration of Freund's complete adjuvant at the base of the tail on day 0. ZSTK474 was orally administered once daily from day 10. The severity of AIA was assessed by measuring the hind paw volume. The number of lymphocytes in inguinal lymph nodes (ILN) was determined by flow cytometry. The in vitro effects of ZSTK474 on the cell proliferation, and the cytokines and prostaglandin E(2) (PGE(2)) production were evaluated by BrdU method, ELISA and cytometric beads array.ZSTK474 ameliorated the progression of AIA. The temporary increases in the number of T cells in ILN, which occurred along with the appearance of arthritis, were inhibited in the ZSTK474-treated groups. In vitro studies revealed that ZSTK474 inhibited the production of IFNγ and IL-17 in concanavalin A-activated T cells. In vitro studies further revealed that ZSTK474 inhibited the proliferation and PGE(2) production by fibroblast-like synovial cells (FLS).ZSTK474 demonstrated prophylactic efficacy in a rat model of rheumatoid arthritis (RA) through inhibition of T cell and FLS functions. It was suggested that the inhibitors of PI3K have therapeutic potential for RA.

Tribological properties of a new and unique thermo-reversible Gel-Lubricant (TR Gel-lube) have been investigated. TR Gel-lube that includes an amide-type gel agent in base fluid is repeatedly able to change from gel state to liquid state at the melting point of its gel agent. Very low friction coefficient is indicated because of adsorption on a metal surface, and the gel agent works as an oiliness agent. In this study, the correlation between the lubricating property and the gel agent's characteristics (chemical structure, content, etc.) was clarified. DSC tester was applied to evaluate the stability of the gel state by change of entropy and the thermodynamic consideration was examined. In addition, lubricating properties under practical conditions such as at high temperature and in the presence of water were proved.

In the present work, the stabilisation of hydrogen bonding of polypropylene glycol at elastohydrodynamic lubrication (EHL) contact was investigated by in situ observation with a micro-Fourier transform infrared spectrometer, and the effect of hydrostatic pressure on infrared (IR) spectra was confirmed using a diamond anvil cell. Polypropylene glycols with different molecular weights were used as sample oils. Polypropylene glycol molecules interact with themselves by hydrogen bonding with their hydroxyl groups. Stability of the hydrogen bonding is observed by IR peak shift of the O–H stretching mode (3400–3700 cm−1). In the case of the dynamic condition under EHL, the C–H stretching mode shifted to a higher wavenumber, whereas the O–H stretching mode shifted to a lower wavenumber at the Hertzian contact region. This result means that the hydrogen bonding of polypropylene glycol was stabilised under high pressure, and the stabilisation of hydrogen bonding by pressure was dependent on the molecular weight of polypropylene glycol. Copyright © 2010 John Wiley & Sons, Ltd.

Novel environmentally adapted lubricant additives were synthesized from cystine (Cys 2 ), an essential amino acid obtained from natural sources. The structural feature of cystine is a dimeric amino acid with a central disulfide bond. The carboxyl groups in Cys 2 were converted to corresponding esters by reaction with long-chain alcohols. The resultant diesters were soluble in poly-alpha-olefin (PAO) and ester-type synthetic oils. The structural features of the new additives include multifunctional groups on the same molecule, such as disulfide as a tribologically active moiety and polar functional groups as anchors to friction surfaces. The additives consist of hydrogen, carbon, nitrogen, oxygen, and sulfur; they are free of phosphorus, chlorine, and metals. The tribological properties of the additives in a solution of synthetic oil were evaluated by performing laboratory tribotests under boundary conditions. The Cys 2 -derived additives exhibited comparable antiwear properties to the conventional additiv...

The phosphoinositide 3-kinases (PI3Ks) transduce important signals involved in T-cell development and activation. Inhibition of the PI3Kδ isoform reportedly decreases regulatory T (Treg) cells and activates anti-tumor immunity in preclinical murine models. PI3K is therefore an attractive target for cancer immunotherapy. Here we explored whether ZSTK474, a selective PI3K inhibitor, which inhibits cancer proliferation by inhibition of activated PI3K in cancer cells, decreases Treg cells, resulting in activation of the anti-tumor immune responses leading to tumor growth inhibition in combination with anti-PD-1 antibody. In syngeneic murine models, ZSTK474 administration decreased Treg cell number in tumors and increased CD8+ T cells / Treg cells ratio, suggesting augmented anti-tumor immunity. ZSTK474 treatment with anti-PD-1 antibody showed far stronger tumor growth inhibition against NY-ESO-1 overexpressing CMS5a cells (CMS5a-NY-ESO-1) and increased tumor specific CD8+ T cells / Treg cells ratio in tumors compared with each monotherapy group. These anti-tumor effect by ZSTK474 was dependent on both CD8+ and CD4+ T cells because depletion of CD8+ or CD4+ T cells from tumor bearing mice abrogated the anti-tumor effect by ZSTK474. We then examined whether ZSTK474 inhibits human Treg cells. CD4+CD25+ Treg cells were isolated from human peripheral blood mononuclear cells (PBMCs) and stimulated with CD3/CD28 antibody and found that ZSTK474 selectively inhibited proliferation of human CD4+CD25+ Treg cells as compared to CD4+CD25- and CD8+ T cells. Furthermore, when PBMCs were stimulated with NY-ESO-1 peptide with/without ZSTK474, NY-ESO-1 specific CD8+ T cells were highly induced by adding ZSTK474. We next examined memory T cell responses in these mice. Re-challenge of CMS5a-NY-ESO-1 cells into tumor-free mice did not lead to tumor growth. Interestingly, when parental CMS5a cells were inoculated into the tumor-free mice, mice treated with anti-PD-1 antibody alone showed an aggressive tumor growth by CMS5a, whereas those treated with combination of anti-PD-1 antibody and ZSTK474 rejected the tumor. These results suggest that treatment with ZSTK474 may promote the development of memory responses against wide ranges of tumor antigens, probably due to changes of intracellular T-cell activation signal to memory formation. Actually, treatment with ZSTK474 increased frequency of memory precursor effector cell (MPEC) in tumor antigen-specific CD8+ T cells. These results suggest that ZSTK474 decreases Treg cells and activates anti-tumor immunity providing a rationale for the combination therapy of a PI3K inhibitor, ZSTK474 and PD-1 blockade. Citation Format: Sho Isoyama, Shigeyuki Mori, Daisuke Sugiyama, Hiroyoshi Nishikawa. ZSTK474, a pan-PI3K inhibitor, enhances the anti-tumor activity of PD-1 blockade by decreasing Treg cells and increasing memory T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4718.

Tribochemistry of metal nitride coatings in the presence of alcohol was investigated by using a stable isotopic tracer. The tribological properties were evaluated by a ball-on-disk type tribo-tester with steel ball and metal nitride coated disk under reciprocating motion. It was found that the friction coefficient of CrN was approximately 60% lower than that of TiN. On the other hand, TiN afforded lower wear than CrN. Considerable amount of deposit was observed on TiN. The rubbed surfaces were chemically analyzed by means of time-of-flight secondary ion mass spectroscopy (TOF-SIMS). In order to eliminate the undesirable fragment ions originated from organic contaminations in TOF-SIMS analysis, pentadeuterioethanol was used as an isotopic tracer. It was found that CrN reacted with alcohol to provide chromium ethoxide as boundary film. On the other hand, transferred Fe ion from the ball was the major contents on rubbed surfaces of TiN coatings.

In order to foster interactive discussions with other countries, this paper offers an overview of residential care for children in Japan and its ongoing development. Japan still relies especially heavily on the residential care system; this is due to the past process of development more than to traditional Japanese culture. The period from the post World War II era to the present is briefly described, including the rapid growth in the number of institutions before 1960, the rather stable period before 1990, the revision of the Child Welfare Act in 1997 permitting the privatization of institutions, and the movement towards problematizing child abuse in the mid 1990s, after which residential institutions were designated as the last resort for maltreated young people. In the present situation, smaller institutions and a foster care system are strongly promoted in accordance with international guidelines for alternative care and the recent governmental guideline based on the Child Rearing Vision of 2010 and the Child Welfare Act of 2016. The task of present Japanese residential care institutions is to realize a family-like environment and a better placement strategy, collaborate more with specialists to improve the standard of care, function in the community as centers for the care of children in need, and expand their care work for young adults and care leavers. The paper concludes by stressing the need for more international exchange among individuals and groups working in Japanese residential care.

The molecular interaction of oleic acid in different base oils at Elastohydrodynamic lubrication (EHL) contact was investigated by means of in-situ observation with micro-Fourier Transform Infrared Spectrometer (FTIR). Moreover, the effect of hydrostatic pressure was confirmed using a diamond-anvil cell (DAC). Poly-α-olefin (PAO) with non-polar, and Polypropylene glycol and Polybutylene glycol (PPG and PBG) which have ether group were used as base oil. When PAO was used, oleic acid interacts with itself to form a dimer. On the other hand, oleic acid interacts with PPG and PBG and exists mainly as a monomeric moelcule. The IR peak of C = O stretching mode of oleic acid dimmer was shifted to lower wavenumber at EHL contact region. The peak shift was not obvious in the case of the monomer. This result means that the hydrogen bonding of the dimer was stabilized under high pressure, but the hydrogen bonding of monomer was not. Copyright © 2010 John Wiley & Sons, Ltd.

A nascent surface has high activity to catalyze the decomposition of lubricants under boundary lubrication conditions. The effects of sulfur-containing, nitrogen-containing, phosphorus-containing additives and phosphate-containing ionic liquid were investigated on the decomposition of synthetic hydrocarbon oil (multialkylated cyclopentane, MAC). The decomposition processes of the lubricants on the nascent surface of bearing steel AISI 52100 were investigated using a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer. Three parameters related to the decomposition process were observed: the induction period for the decomposition, the desorption rate of gaseous products, and the critical load for the activation of the decomposition. The order of efficiency of additives in extending the induction period was: sulfur-containing additive (S)

The role of di-tert-dodecyl disulfide as an additive in the decomposition process of hydrocarbon oil on the nascent surface of bearing steel 52100 was investigated by a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer (Q-MS). After the formation of a nascent surface, hydrogen and gaseous hydrocarbons desorbed as tribochemical reaction products. The desorption rate of gaseous hydrocarbons decreased significantly when the additive was introduced. The additive prolonged the induction period of the decomposition. XPS and ToF-SIMS analysis revealed that additive molecules and lubricant molecules competitively chemisorbed on the nascent surface and reaction occurred by the formation of iron sulfide, which poisoned the catalytic activity of active sites leading to deactivation. As a result, decomposition of hydrocarbon oil decreased significantly.

Tribological properties and the decomposition process of ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide) on a nascent surface of bearing steel 52100 were investigated by a ball-on-disk friction tester in a vacuum chamber equipped with a quadrupole mass spectrometer (Q-MS). Ionic liquids exhibited better tribological properties than synthetic hydrocarbon oil (multialkylated cyclopentane (MAC)) in high vacuum conditions. The induction period for decomposition of MAC was about 10 km, while no obvious gaseous products were observed for ionic liquids even after a sliding distance of 22 km under the same mechanical conditions. The mass spectra indicated that both the anionic and cationic moieties of ionic liquids decomposed on the nascent steel surface during friction processes. The cationic moiety with a longer alkyl chain was more difficult to decompose on the nascent steel surface than that with a shorter alkyl chain. XPS analysis revealed that the tribofilm formed by ionic liquid was mainly composed of FeF2 and FeS, which deactivated the nascent surface. As a result, desorption rate of gaseous products decreased appreciably comparing with MAC. The critical load for the mechanical activation of the decomposition correspondingly increased from 1.1 N of MAC to 8 N of ionic liquids.

A nascent surface has high activity to catalyze the decomposition of a lubricant under boundary lubrication conditions. To reduce the decomposition of a lubricant (multialkylated cyclopentane, MAC), tricresyl phosphate (TCP) was introduced as an additive. The tribological properties and decomposition process of lubricants on the nascent surface of bearing steel 52100 were investigated by a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer (Q-MS). The addition of TCP prolonged the induction period for decomposition of the lubricant. During the friction processes, hydrogen and gaseous hydrocarbons desorbed as tribochemical reaction products. XPS analysis revealed that the tribofilm from the additive was mainly composed of iron phosphate, which decreased the probability of generating a nascent surface, resulting in the reduction of desorption rate of gaseous products. The critical load for the mechanical activation of the decomposition correspondingly doubled.

A monomolecular film of octadecanoic acid on a Si(1 0 0) surface was prepared using a computer-controlled Langmuir trough. The tribological properties were acquired by a ball-on-flat type tribo-tester under reciprocating motion. Considerable effects of ball material on lifetime for low friction were observed; a glass ball was excellent while a steel ball was poor. The rubbed surfaces on ball and flat were studied by time-of-flight secondary ion mass spectroscopy. Transfer of the carboxylic acid and silicon onto the ball surface from the flat specimen was found. The role of the transferred acid that prolongs the lifetime of low friction was proposed. It should be emphasized that deuterium-labeled carboxylic acid makes the target of TOF-SIMS analysis clear.

Poly(tetrafluoroethylene) (PTFE)-blended poly(ether-etherketone) (PEEK)-based materials for bearings was evaluated by ring-on-disc test equipment. The role of PTFE on load carrying capacities was studied from the viewpoint of tribochemistry. The load carrying capacities of PEEK-based materials were improved by the addition of PTFE. The dispersion degree of PTFE in PEEK strongly affected the tribological properties. Time-of-flight secondary ion mass spectroscopy and X-ray photoelectron spectroscopy were employed to study the surface chemistry of the rubbed surface. The results indicate that the formation of boundary film composed of PTFE is beneficial to improve load carrying capacities. Copyright © 2008 John Wiley & Sons, Ltd.

The initial stage of boundary film formation from overbased calcium sulfonate at steel–DLC (diamond like carbon) contact was studied. A running-in process was clearly observed by the combination of fresh DLC with fresh steel or fresh DLC with rubbed steel. On the other hand, rubbed DLC does not possess the running-in process. Surface analysis by TOF-SIMS was applied to investigate the formation process and structure of films. It was found that the transfer of iron from the steel ball on to the DLC surface plays a significant role in the formation of boundary film. The depth profile of the film was also obtained by means of an etching technique. The boundary film on steel ball and DLC are mainly composed of iron and calcium oxide. However the depth profiles indicate that distribution of calcium oxide on steel ball is different from that on DLC coated disk.

The tribological properties of trifluorotris(pentafluoroethyl) phosphate [(C2F5)3PF 3 − , FAP]-derived ionic liquids were evaluated under boundary conditions. The anion is hydrophobic in comparison with bis(trifluoromethylsulfonyl)imide [(CF3SO2)2N−, TFSI]. 1,3-Dialkylimidazolium salts of FAP provided much lower friction than 1,3-dialkylimidazolium salts of TFSI. In addition, the FAP salts exhibit better anti-wear properties than the TFSI salts. Another advantage of the FAP anion is availability of several cations to prepare ionic liquids. For example, tetraalkylphosphonium, N,N-dialkylpyrrolidium, and tetramethylisouronium salts of FAP provided friction coefficient of approximately 0.1. Straight-chain carboxylic acids as model friction-reducing additives improved the tribological properties of the FAP salts. Surface analyses were conducted to study the boundary film formed by rubbing. It was found that the boundary film is composed of adsorbed anion on uppermost surfaces and reacted anion on sub-surfaces. The model friction-reducing additives were found on the rubbed surfaces.

Molecular design of wear-preventing and friction-reducing additives for ionic liquids is described. The tribological properties of carboxylic acid-derived additives were evaluated by a ball-on-flat type tribotest under reciprocating motion. Tetraalkylammonium and tetraalkylphosphonium salts of N-benzyl-protected aspartic acid were dissolved in 1-alkyl-3-methylimidazolium-derived ionic liquids. They prevented wear remarkably and reduced friction fairly. Influences of alkyl group in imidazolium molecule on additive response were observed. In tetraalkylammonium-derived ionic liquids, the additive reduced wear but did not reduce friction under these conditions. The salt of N-acetyl-protected glutamic acid prevented wear, but did not reduce friction. Copyright © 2008 John Wiley & Sons, Ltd.

The tribological properties of a new unique thermo-reversible Gel-Lubricant (TR Gel-Lube) were investigated. TR Gel-Lube which includes 10-40% of amide type gel agent in base fluid, is repeatedly able to change from gel-state to liquid-state at the melting point of its gel agent. TR Gel-Lube can be used as an impregnant for porous-material due to its physical state change. TR Gel-Lube indicated lower frictional and better lubricating properties than that of conventional greases. In particular, when TR Gel-Lube was sintered in a copper-type sintered bearing, a lower friction coefficient compared with oils was observed. In this study, to clarify the mechanisms of TR Gel-Lube, the behavior of gel agent on the EHL region was investigated by ball-on-disk tribometer. It was found that gel agent played a key role in the lubricating properties. Some mechanisms such as adsorbed film formation, smooth surface formation and solid like film formation are proposed.

The tribological properties of poly(ether-ether-ketone) (PEEK) against steel was evaluated by a ring-on-flat type tribo-test under rotating motion. Addition of poly(tetrafluoroethlene) (PTFE) as solid lubricants improved the load-carrying capacity of the material. The role of PTFE was studied by means of time of flight secondary ion mass spectroscopy (TOF-SIMS). The transfer of PTFE from the PEEK surface onto steel surface was found to be beneficial for preventing seizure.

In the cold rolling of aluminum foil, coolants made with nonaromatic base oils provide poor lubricity compared with coolants made with conventional base oils. But there is no clear difference in lubricity between nonaromatic and conventional base oils in the case of the rolling of aluminum sheet. In evaluations of the adsorption activity of model base oil components, alkylbenzene with a longer alkyl chain shows the potential to enhance the adsorption activity of alcohol onto the nascent aluminum surface. In experimental rolling, furthermore, the lubrication performance of coolants using nonaromatic base oils can be improved with the addition of dodecylbenzene. The addition of 10 mass% of dodecylbenzene into a nonaromatic coolant is sufficient for practical lubrication performance in the cold rolling of aluminum.

Various synthetic esters are widely applied as lubricating fluid to reduce friction and wear at tribological contact. Among them low viscous synthetic esters are expected to improve fuel efficiency by minimizing the fluid friction. These low viscous esters are composed of short-chain fatty acids. Therefore, low viscous synthetic esters are inherently polar molecules. Since efficiency of anti-wear additives decreases with increase of polarity of the base oil, new additive technology is requested. In this work, hydroxyalkyl phosphates [P(O)(OCHRCH2OH)3], and hydroxyalkyl phosphonates [P(OH)n(OCHRCH2OH)3−n, where n=1,2] are proposed as novel anti-wear additives for polar synthetic esters. The anti-wear additives are evaluated under the boundary conditions. The additives prevent wear in polar esters, in which conventional anti-wear additives do not work at all. Interestingly, effects of substituent in additive molecule on anti-wear properties are found. Alkyl and aryl derivatives reduce wear remarkably, whereas allyl derivatives exhibit poor results. It is speculated that the anti-wear inefiiciency of allylic compounds is due to auto-oxidation of the additives. A facile preparative method for hydroxyalkyl derivatives characterizes the present additive system. They are prepared in situ by simply mixing phosphonic acid and substituted epoxides. Flexiblity of lubricant design can be made possible by the present additive system.

Ionic liquids are unique compounds, which exhibit low viscosity, non-flammability, low vapor pressure, and extremely high thermal stability. Therefore, they are expected as candidates for advanced lubricants. Several ionic liquids, derived from cations such as imidazolium, pridinium, ammonium, and anions such as BF 4 - , bis(trifluoromethylsulfonyl)imide ( TFSI - ) were examined under boundary conditions. It was found that tribological properties of ionic liquids are better than those of conventional lubricants such as synthetic hydrocarbons, synthetic esters, and fluorinated ethers. Careful analysis of worn surface revealed that tribochemical reactions of ionic liquids take place under these conditions. For example, organic fluoride, iron fluoride, iron sulfate derived from anionic moiety of the ionic liquids were detected by the instrumental surface-analysis with TOF-SIMS and XPS. Tricresylphosphate (TCP) and dibenzyldisulfide (DBDS) were found to improve anti-wear properties of ionic liquids to some extent. Interestingly, both additive-derived compounds and anionic moiety derived ones were detected on the worn surface. Moreover, additive response of ionic liquids was found to be superior to those for conventional lubricants. It was speculated that the unique tribochemical reactions will lead us to design tailor-made lubricants. Lubrication mechanism of ionic liquids is discussed from the viewpoint of tribochemistry.

Hydrocarbon oil with low vapor pressure has been used as a lubricant in high-vacuum conditions. Decomposition of the oil under boundary lubrication conditions was studied by investigating desorption of hydrogen and hydrocarbons, generated by tribochemical reaction occurred on nascent surface of 52100 steel during the sliding process in a ball-on-disk type sliding tester. Gaseous products by tribochemical decomposition were monitored by a quadrupole mass spectrometer (Q-MS), which would reveal the decomposition mechanism of hydrocarbon oil. It is found that tribochemical reactions of hydrocarbon oil occurred on active sites on steel generated by sliding, the desorption amount of hydrogen and gaseous hydrocarbons increased linearly with sliding velocity, and parabolically with load. A critical load for the activation of decomposition of the hydrocarbon oil on bearing steel was found to be about 1.1 N. In this paper, the decomposition mechanism of hydrocarbon oil was also explored.

The effects of a self-assembled monolayer (SAM) coating on the friction and pull-off forces were determined by using two-dimensional asperity arrays on silicon wafers. The arrays were coated with SAM composed of one of five different alkylchlorsilanes. First, two-dimensional asperity arrays were created by using a focussed ion beam (FIB) system to mill patterns on silicon plates. Each silicon plate had different patterns of equally spaced asperities. Each pattern (5 × 5 μm2) had a different radius of curvature of the asperity peaks, ranging from about 200 to 2500 nm. Then, each silicon plate was immersed in a solution of a different alkylchlorsilane in hexane (either hexyltrichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, tetradecyltrichlorosilane, or octadecyltrichlorosilane), thus coating the asperity arrays with SAM. The friction and pull-off forces on the SAM-coated arrays were measured by using an atomic force microscope (AFM) that had a square flat probe. The pull-off force for SAM-coated silicon was roughly proportional to the radius of curvature of the asperity peaks. The magnitude of the pull-off force corresponded approximately to the capillary force calculated by using the contact angle of water on the surface of SAM. The friction coefficient correlated with the inverse of the alkyl-chain length of the SAM.

The tribological properties of ionic liquids were outlined from the viewpoint of tribo-chemistry. The tribological properties of two hydrophobic anions, trifluorotris (pentafluoroethyl) phosphate (FAP) and bis (trifluoromethylsulfonyl) imide (TFSI), were compared by a pendulum type friction test. FAP salts of imidazolium possess much better lubricity than TFSI salts of imidazolium. Tribo-chemical reactions of the ionic liquids were studied by time-of-flight secondary ion mass spectroscopy. It was found that content of phosphorus on the inside wear track was higher than that on the outside wear track. The results indicate that reaction of FAP took place under the tribo-chemical conditions. Straight-chain carboxylic acids were found to improve tribological properties of the ionic liquids. Direct interaction of the acid with the rubbed surfaces was confirmed by using stable isotopic tracers.