Behavior of Ionic Liquids Under Nanoconfinement Greatly Affects Actual Friction

Ionic liquids (ILs) are organic salts consisting of anions and cations that exist as liquids at room temperature. ILs exhibit many attractive properties such as negligible volatility, low flammability, and relatively high thermal stability. These properties can be varied in a controlled fashion through systematic changes in the molecular structure of their constituent ions. Some recent studies have aimed to use ILs as new lubricant materials. However, the behavior of ILs as lubricants on the sliding interfaces has not been elucidated. In this chapter, we describe the nano- and macrolubrication properties of some ILs with different types of anions using resonance shear measurement (RSM) and conventional ball-on-plate-type tribotests, respectively. This study reveals that the properties observed by RSM for nanoscale systems can provide important insights for the study of the friction coefficients (macrolubrication properties) obtained by tribotests

Development of Low-Friction Ion Gels for Industrial Applications

Friction reduction is imperative for improving the service life and energy efficiency of mechanical systems. Ion gels using ionic liquids (ILs) as swelling agents are expected to be stable gel lubricants owing to the high thermal stability and negligible volatility of ILs; they can maintain their swollen state even under harsh conditions. Therefore, we investigated two types of ion gels: an IL-substituted double-network gel (DN ion S-gel), in which the water in the DN hydrogel is replaced by the IL 3-ethyl-1-methyl-imidazolium ethylsulfate; and a DN ion gel containing N,N-diethyl-N-(2-methoxyethyl)-N-methyl-ammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI), where one of the polymer backbones is a network of poly(N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide), an IL-type polymer based on our previous synthetic study of IL polymer technology. The DN ion S-gel and DN ion gel achieved compression strengths of 25 and 30 MPa, respectively, and were thermally stable until 196°C and 335°C (10% weight-loss temperature), respectively. The coefficient of friction remained stable and low (0.02) after repeated measurements under harsh conditions (high temperature or vacuum conditions), affirming the durability of the DN ion gel

Rho and Anillin-dependent Control of mDia2 Localization and Function in Cytokinesis

Diaphanous-related formin, mDia, is an actin nucleation/polymerization factor functioning downstream of the small GTPase Rho. We found that, in addition to the Rho GTPase-mediated activation, the interaction between mDia2 and anillin is required for the localization and function of mDia2 in cytokinesis

Characteristics of Ferrite-Rich Portland Cement: Comparison With Ordinary Portland Cement

The cement industry is an energy-intensive industry, and improving the energy efficiency of cement has become necessary to reduce its carbon footprint and to compete in the global market. Clinker production consumes more than 90% of the total energy used in the cement industry. Therefore, a reduction in the burning temperature of the cement clinker can reduce the energy consumption; however, it alters the mineralogy of the clinker composition. Ferrite-rich Portland cement can be produced by lowering the burning temperature by ~100°C (i.e., at 1,350°C), which can reduce the energy consumption by ~5% in comparison with ordinary Portland cement (OPC) clinker. In this study, the hydration reaction and properties of the ferrite-rich Portland cement were examined by experimental techniques and thermodynamic modeling approach, and the results were compared with that of OPC. The produced ferrite-rich cement has almost twice the amount of ferrite phase and half the amount of belite phase contents present in the OPC. The hydration reaction and the composition of hydrates were studied by the X-ray diffraction (XRD)/Rietveld analysis and thermogravimetry (TG) and differential thermal analysis (DTA). The different proportions of the ferrite and belite phases in ferrite-rich cement change their hydration reaction from that of the OPC, but not the total hydration of cement. The XRD results reveal similar phases in both the cements, and the analysis could not identify the new phases formed in the ferrite-rich cement. An equal degree of hydration and quantified hydrates at the early age results in almost identical initial and final setting times in both the cements. The ferrite-rich cement demonstrates a high early strength and relatively slower strength development; however, it can develop adequate strength at 28 days. The thermodynamic model predicts the hydration of ferrite-rich cement and shows comparatively high amount of Fe-containing phases, mainly Fe-ettringite and Fe-siliceous hydrogarnet. Model predictions of the hydrates compositions agreed with the experimental results, and a relationship between the predicted total porosity and the measured compressive strength was derived

Expression of myogenin, MyoD and MHC isoforms in regenerating skeletal muscle.

骨格筋再生過程におけるミオシン重鎖(MHC)アイソフォーム発現とmyogenin，MyoDタンパクの発現様式との関連性を検討するために，塩酸ブピバカインを用いてマウスヒラメ筋損傷モデルを作成し，損傷筋の再生過程を組織形態学的に確認すると同時に，再生各段階におけるMHCアイソフォームと，myogeninおよびMyoDタンパク発現を経時的に検索した．本研究における筋損傷は塩酸ブピバカインをマウス(C57BL/10SnSlc)のヒラメ筋に注入することで作成した．組織学的には，塩酸ブピバカイン投与後3日目で筋線維はほとんど消失し，処置後6日目で中心核を有する再生筋線維がかなり出現し，処置後28日目では対照群のものと同程度まで回復した．生化学的分析では，対照群ヒラメ筋はMHCⅠ(34．3±1．7%)とMHCⅡa(65．7±1．7%)で構成されていた．実験群ヒラメ筋ではMHCⅠは処置後14日目まで減少し，その後増加傾向を示し，処置後90日目では36．3±2．9%となった．また，正常ヒラメ筋では検出されない速筋型MHC(MHC Ⅱd，MHC Ⅱb)が処置後3日目から28日目まで検出された．Western blotを用いた分析では，myogeninタンパク正常ヒラメ筋（遅筋）で検出された一方，前脛骨筋（速筋）においては検出できなかった．実験群ヒラメ筋では，myogeninは対照群と比較して処置後３日目より増加し（3．1±0．5），処置後６日目でピークに達した（5．8±0．8）．それからmyogeninタンパクは徐々に減少していったが，処置後90日目においてもなお対照群ヒラメ筋の1．8倍の発現を維持し続けた．一方，MyoDタンパクは正常前脛骨筋において正常ヒラメ筋の3．3倍の発現が認められた．MyoDは処置後３日目で対照群ヒラメ筋と比較して5．4倍になりピークに達した．その後は徐々に減少し始めた．しかし処置後90日目においても2．2倍の発現があった．これらのことから筋の再生過程においては速筋タイプの筋細胞が出現するmyogeninとMyoDは衛星細胞の分化と筋の再生に密接に関係していることが示唆された．To investigate the precise mechanism of skeletal muscle cell regeneration, the changing pattern ofmyosin heavy chain(MHC)isoforms during the regenerating process was observed with relation to theactivation of myogenin and MyoD. In addition, histopathological observation of the damaged muscles wasperformed throughout the experiment.In this study, muscle damage was induced by intramuscular injection of bupivacaine hydrochloride in thesoleus muscle of mice (C57BL/10SnSc). In the light microscopic observation, muscle cells had almost disappeared at 3 days after bupivacainetreatment with severe inflammatory cell infiltration. At 6 days after treatment, a considerable number ofregenerating muscle cells containing centrally located nuclei appeared in the damaged soleus muscle. At28 days, these regenerating muscle cells showed almost the same appearance as the control muscle cellscontaining subsarcolemmal nuclei, although a small number of muscle cells with central nuclei were stillrecognized.In the biochemical analysis, control soleus muscles contained only MHC I (34.3±1.7 %)and MHC IIa(65.7±1.7 %). In the damaged muscles, MHC I was decreased toward 14 days after treatment, and thengradually increased. At 90 days, the contents of MHC I was finally recovered to 36.3±2.9 %.0 In addition,MHC IId and MHC IIb appeared in the damaged muscle from 3 to 28 days after treatment. However, theyhad disappeared at 90 days.Using western blot analysis, myogenin protein was recognized in the control soleus muscles (slow typemuscle), while the myogenin could not be found in the first type muscle of the anterior tibial muscle. Themyogenin contents increased to about three fold (3.1±0.5)at 3 days after treatment compared withthose of control muscles and reached the maximum level (5.8±0.8)at 6 days after treatment. Then, myogenin contents gradually decreased,although they still remained high (1.8 times)at the end of experiment (90 days after treatment). Incontrast to the myogenin protein, a high level (3.3 times)of MyoD protein was detected in the anteriortibial muscle compared with that of control soleus muscles. In the damaged soleus muscles, MyoDcontents reached a maximum level (5.4 times)at 3 days after treatment compared with that of controlsoleus muscles, and then gradually decreased toward the end of experiment. However, MyoD protein stillremained 2.2 times compared with that of control soleus muscles. These findings described above indicate that, 1)a property of fast type muscle cells appeared in theregenerating muscle cells during the regenerating process, and 2)myogenin and MyoD are closelyrelated to the differentiation of the satellite cells and regeneration of the skeletal muscle cells

The role of astrocytes during repair of cerebral infarction in mdx mice

様々な大きさのジストロフィンアイソフォーム(427kDa, 260kDa, 140kDa, 116kDa, 71-75kDa)が広く体内に存在していることはよく知られている.中枢神経系においては71-75kDaのDp71が著明に多く,毛細血管の内皮の基底膜に接しているアストロサイトの細胞質に局在することが報告されている.しかしながらDp71の機能についてはよくわかっていないことが多い.そこで今回,脳組織におけるDp71の役割を調べるために,コントロールマウス(wild-typeマウス)およびデュシャンヌ型筋ジストロフィーモデル動物であるmdxマウスを用いて実験的脳梗塞を作成し,その治癒過程を形態学的に観察した.また,GFAPおよびDp71に関して生化学的に分析をおこなった.HE染色およびGFAP免疫組織学的染色の結果から,形態学的にはmdxマウスとコントロールマウスの脳に違いは認められなかった.しかしながら,mdxマウスの脳において,Dp71の発現量がコントロールマウスよりも少ないことがわかった.またmdxマウスにおいて,脳梗塞の修復過程におけるアストロサイトの反応がコントロールマウスよりも弱いことがわかった.これらの結果から,mdxマウスの脳において,アストロサイトの機能,アストロサイトの血管新生に関わる機能の障害されていることが示唆された.It is now well known that dystrophin isoforms (427kDa, 260kDa, 140kDa, 116kDa, 71-75kDa) are widely distributed throughout our body. In the central nervous system a considerable amount of Dp71 (71-75kDa) is found in the perivascular cytoplasm of the astrocytes. However, the function of this dystrophin is still unknown. To investigate the role of Dp71 in the brain tissue, cerebral infarction was induced in the control (wide-type) mouse and mdx mouse which is known as an animal model of human muscle dystrophy (Duchenne type), and morphological changes of the infarcted area were observed during repair of the infarction. In addition, biochemical analysis of GFAP and Dp71 was carried out in the brain of the control and mdx mouse. In our present study, there were no differences in brain morphology between mdx and control mouse as revealed in H-E stain and GFAP immunohistochemistry. However, the Dp71 were smaller in quantity in the brain of the mdx mouse than that of the control mouse. The reaction of astrocytes during repair of serebral infarction was distinctly delayed in the mdx mouse compared with that of the control mouse. These findings suggest that the astrocytes in the brain of the mdx mouse are functionally impaired including perivascular cytoplasmic processes with relation to neo-vascularization

Function of skeletal muscle sarcoplasmic reticulum and expression of sarcoplasmic reticulum Ca2+-ATPase in right congestive heart failure rats

右心不全に伴って,速筋および遅筋の筋小胞体Ca2+取り込み能が減少するという仮説を検証した.右心不全は,モノクロタリン(30 ㎎/㎏)を投与することにより引き起こし,投与後4週で,長指伸筋およびヒラメ筋を両後肢から採取した.筋の疲労耐性は,連続的な強縮刺激を行うことにより測定した.長指伸筋では刺激開始1分後,ヒラメ筋では4分後の張力を測定し,初期値に対するそれらの割合を疲労の指標とした.長指伸筋およびヒラメ筋の疲労耐性は,右心不全群で有意に低下した.筋小胞体Ca2+取り込み速度は,Indo-Ⅰを付加したホモジネートで測定した.その結果,Ca2+取り込み速度は,長指伸筋で25.4%(p<0.01),ヒラメ筋で30.4%(p<0.05)低下した.このCa2+取り込み速度の低下は,筋小胞体Ca2+-ATPaseタンパク量の低下と一致した.筋小胞体Ca2+取り込み能の低下は,筋張力の低下を引き起こし,このCa2+ handlingの低下は,少なくとも右心不全による運動耐容能の低下の一因であろう.In this study, we investigated the hypothesis that right congestive heart failure (CHF) would impair sarcoplasmic reticulum (SR) Ca2+ uptake in skeletal fast- and slow-twitch muscles. To induce CHF, the rats were injected with monocrotalin (30 ㎎/㎏). After 4 weeks of injection, extensor digitorum longus (EDL) and soleus (SOL) muscles were sampled from both hind limbs. Muscle fatigue resistance was measured in vitro as the relative decline in force production of tetanic contraction induced by electrical stimulation over 1 and 4 min in EDL and SOL, respectively. Evaluation of fatigue characteristics showed that CHF significantly reduced fatigue resistance in both muscles under study.SR Ca2+uptake rate wasmeasured in vitro with Indo-I on muscle homogenates. As hypothesized, Ca2+uptake rate was decreasedby 25.4%(P < 0.01) and 30.4%(P < 0.05) in EDL and SOL, respectively. This decline in Ca22+uptake ratewas accompanied by an immunochemically determined decrease in SR Ca2+-ATPase protein. Taking intoaccount previous findings that the depressed SR Ca2+uptake leads to the reduce in muscle forceproduction, these results suggest that impaired SR Ca2+handling capacity in skeletal muscle may accountat least partly for deteriorations in exercise tolerance resulting from right CHF

Candida-induced histamine release from basophils: relationship to house dust- and anti-IgE-induced secretion

Candida albicans-induced histamine release from basophils was studied in 54 patients with bronchial asthma in comparison with the release caused by house dust and anti-IgE. The release of histamine induced by C. albicans and that induced by house dust were closely related to the serum levels of specific IgE antibodies as expressed by RAST scores. A correlation of C. albicans-induced histamine release with the release caused by anti-IgE was not generally observed. On the other hand, a close correlation was found between house dust- and anti-IgE-induced histamine release. It was suggested from these results that the differences between C. albicans- and house dust-induced histamine release might be due to the different antigenicity of the two allergens.</p