Adsorption Characteristics and Mechanical Responses of Lubricants Containing Polymer Additives under Fluid Lubrication with a Narrow Gap.

The adsorption behavior of poly(methyl acrylate) (PMA)-based polymer additives and their mechanical response under fluid lubrication in narrow gaps were investigated by using neutron reflectometry, microchannel devices, and the narrow gap viscometer. The surface adsorption layer formed by the polymer additive in a stationary field that was investigated by neutron reflectometry was only about 3 nm thick. On the other hand, when the sample oil containing the polymer additive was flowed into the microchannel device with channels about 500 nm deep, the adsorption layer grew over a long period of time and eventually formed a layer that appeared to be more than 100 nm thick. The mechanical response was measured during one-directional rotation with a constant gap length by using the narrow gap viscometer. The results showed that the effective viscosity increased in the low shear rate range. The same behavior was also observed in the reciprocating rotational tests, where the mechanical response showed a distinctive distortion only when the shear rate was low near 0 rpm. The results of the neutron reflectometer, incorporating the narrow gap viscometer, showed no effect of the rotational speed with regard to the structure of the homogeneous layer over a large area. However, the discrepancy between the reflectivity profile and the fitting curve became progressively more pronounced with time, confirming the formation of inhomogeneous structures with time. It is finally suggested that the inhomogeneous structure is due to the formation of local aggregates by PMA molecules, and it acts as flow resistance only in the low shear rate, resulting in an increase in effective viscosity.

Neutron reflectometry under high shear in narrow gap for tribology study.

An operando analysis method has been established for evaluating the interfacial structure of an adsorbed layer formed by an additive on a metal surface under fluid lubricated conditions. A parallel-face narrow gap viscometer installed in an energy-resolved neutron reflectometer is used to evaluate the change in the interfacial structure under high shear. The viscometer was designed to operate at a high shear rate while maintaining a µm-order constant gap between two parallel surfaces. When an additive-free base oil was sandwiched in the gap, the neutron reflectivity profiles without and with upper surface rotation were the same. This demonstrates that the reflectivity profiles can be accurately measured regardless of whether the upper surface is rotated. When a base oil containing a polymethacrylate-based additive was sandwiched in the gap, both the thickness and density of the adsorbed additive layer in the rotation (shear field) condition were lower than those in the non-rotation (static) condition. This demonstrates that the proposed method can be used to analyse the structural changes in the adsorbed layer formed by an oil additive on a surface. This combination of a neutron reflectometer and narrow gap viscometer is a promising approach to near-future tribological studies.

Comparison of respiratory muscle strength in individuals performing continuous and noncontinuous walking exercises in water after the 6-week program.

This study aimed to compare respiratory muscle strength in individuals performing continuous and noncontinuous walking exercises in water after the 6-week program. Twenty-nine healthy men were randomly divided into a continuous group (CG, n=14) and a noncontinuous group (NG, n=15). Firstly, both groups executed the 6-week program which set them to walk for 30 min, 4 times per week, over 6 weeks in a pool with the adjusted intensity that their walking speed increased the heart rate to 60% of the predicted maximum. After the 6-week program, participants in the CG continued the water-walking program for 4 weeks while those in the NG discontinued the water-walking program. In both groups, respiratory muscle strength evaluated by maximum inspiratory pressure (PImax) and maximum expiratory pressure (PEmax) increased significantly after the 6-week program compared with pre-exercise value. Compared to the value after the 6-week program, PEmax increased significantly in the CG after 10 weeks (P<0.05), but the PImax showed no significant change. Compared to the value after the 6-week program, after 10 weeks, in the NG, PEmax decreased significantly, with a considerable decrease after 9 and 10 weeks compared to the CG (P<0.05). The PImax in the NG significantly decreased after 10 weeks from the value observed after the 6-week program. We demonstrated that 6 weeks of walking in water at 60% of the predicted maximum heart rate enhances PImax and PEmax, and that PImax and PEmax decrease in 4 weeks without a water-walking program.

Partial Range of Motion Exercise Is Effective for Facilitating Muscle Hypertrophy and Function Through Sustained Intramuscular Hypoxia in Young Trained Men.

Goto, M, Chikako, M, Hirayama, T, Terada, S, Nirengi, S, Kurosawa, Y, Nagano, A, and Hamaoka, T. Partial range of motion exercise is effective for facilitating muscle hypertrophy and function through sustained intramuscular hypoxia in young trained men. J Strength Cond Res 33(5): 1286-1294, 2019-The acute response to and long-term effects of partial range of motion exercise (PRE) and full range of motion exercise (FRE) of elbow extensors were compared in young trained men. The PRE was expected to increase the intramuscular hypoxic environment, which was theorized to enhance muscular hypertrophy. Forty-four resistance-trained men were divided into 2 training groups, PRE (n = 22) or FRE (n = 22) group, and performed the PRE or FRE acute exercise protocol. The PRE (elbow range from 45° to 90°) and FRE (from 0° to 120°) acute protocols consisted of 3 sets of 8 repetitions, with an 8RM, and an equivalent workload. After the initial testing, the training program for each group, comprised 3 training sessions per week for 8 weeks, was started. The acute responses of area under the oxygenated hemoglobin (Oxy-Hb) curve, blood lactate concentration, and root mean square of electromyography were significantly higher both before and after PRE than FRE training. Long-term effects were produced by both PRE and FRE, with significant (p ≤ 0.05) increases in cross-sectional area (CSA) of triceps brachii and isometric strength. The CSA increased significantly greater after PRE (48.7 ± 14.5%) than after FRE (28.2 ± 10.9%). Furthermore, during the PRE program, a positive correlation was detected between the percent increase in CSA and area under the Oxy-Hb curves before and after 8-week exercise training (before 8-week exercise training: r = 0.59, after 8-week exercise training: r = 0.70, p < 0.01). These results suggest that intramuscular hypoxia might facilitate muscular hypertrophy with PRE being more effective than FRE.

Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy.

To observe in situ the adsorption of fatty acid onto metal surfaces, cross-sectional images of the adsorption layer were acquired by frequency-modulation atomic force microscopy (FM-AFM). Hexadecane and palmitic acid were used as the base oil and typical fatty acid, respectively. A Cu-coated silicon wafer was prepared as the target substrate. The solvation structure formed by hexadecane molecules at the interface between the Cu substrate and the hexadecane was observed, and the layer pitch was found to be about 0.6 nm, which corresponds to the height of hexadecane molecules. This demonstrates that hexadecane molecules physically adsorbed onto the surface due to van der Waals forces with lying orientation because hexadecane is a nonpolar hydrocarbon. When hexadecane with palmitic acid was put on the Cu substrate instead of pure hexadecane, an adsorption layer of palmitic acid was observed at the interface. The layer pitch was about 2.5-2.8 nm, which matches the chain length of palmitic acid molecules well. This indicates that the original adsorption layer was monolayer or single bilayer in the local area. In addition, a cross-sectional image captured 1 h after observation started to reveal that the adsorbed additive layer gradually grew up to be thicker than about 20 nm due to an external stimulus, such as cantilever oscillation. This is the first report of in situ observation of an adsorbed layer by FM-AFM in the tribology field and demonstrates that FM-AFM is useful for clarifying the actual boundary lubrication mechanism.

Identification and characterization of the direct interaction between methotrexate (MTX) and high-mobility group box 1 (HMGB1) protein.

BACKGROUND: Methotrexate (MTX) is an agent used in chemotherapy of tumors and autoimmune disease including rheumatoid arthritis (RA). In addition, MTX has some anti-inflammatory activity. Although dihydrofolate reductase (DHFR) is a well-known target for the anti-tumor effect of MTX, the mode of action for the anti-inflammatory activity of MTX is not fully understood. METHODOLOGY/RESULT: Here, we performed a screening of MTX-binding proteins using T7 phage display with a synthetic biotinylated MTX derivative. We then characterized the interactions using surface plasmon resonance (SPR) analysis and electrophoretic mobility shift assay (EMSA). Using a T7 phage display screen, we identified T7 phages that displayed part of high-mobility group box 1 (HMGB1) protein (K86-V175). Binding affinities as well as likely binding sites were characterized using genetically engineered truncated versions of HMGB1 protein (Al G1-K87, Bj: F88-K181), indicating that MTX binds to HMGB1 via two independent sites with a dissociation constants (KD) of 0.50±0.03 µM for Al and 0.24 ± 0.01 µM for Bj. Although MTX did not inhibit the binding of HMGB1 to DNA via these domains, HMGB1/RAGE association was impeded in the presence of MTX. These data suggested that binding of MTX to part of the RAGE-binding region (K149-V175) in HMGB1 might be significant for the anti-inflammatory effect of MTX. Indeed, in murine macrophage-like cells (RAW 264.7), TNF-α release and mitogenic activity elicited by specific RAGE stimulation with a truncated monomeric HMGB1 were inhibited in the presence of MTX. CONCLUSIONS/SIGNIFICANCE: These data demonstrate that HMGB1 is a direct binding protein of MTX. Moreover, binding of MTX to RAGE-binding region in HMGB1 inhibited the HMGB1/RAGE interaction at the molecular and cellular levels. These data might explain the molecular basis underlying the mechanism of action for the anti-inflammatory effect of MTX.

Associations between dietary n-6 and n-3 fatty acids and arachidonic acid compositions in plasma and erythrocytes in young and elderly Japanese volunteers.

BACKGROUND: We reported that the compositions of arachidonic acid (ARA) in erythrocytes and plasma phospholipids (PL) in the elderly were lower than those in the young, though the ARA intake was nearly identical. OBJECTIVE: We further analyzed data in four study groups with different ages and sexes, and determined that the blood ARA levels were affected by the kinds of dietary fatty acids ingested. METHODS: One hundred and four healthy young and elderly volunteers were recruited. Dietary records together with photographic records from 28 consecutive days were reviewed and the fatty acid composition in plasma lipid fractions and erythrocyte PL was analyzed. RESULTS: No correlations for ARA between dietary fatty acids and blood lipid fractions were observed. A significant negative correlation between eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) intake and ARA composition in erythrocyte PL was observed. ARA composition in erythrocyte PL was significantly lower in elderly subjects than in young subjects, because EPA and DHA intake in elderly subjects was higher than in young subjects. However, after removing the effect of dietary EPA+DHA intake, the ARA composition in erythrocyte PL in elderly subjects was significantly lower than that in young subjects. CONCLUSIONS: Changes in physical conditions with aging influenced the low ARA composition of erythrocyte in elderly subjects in addition to the effects of dietary EPA and DHA.

Age-related changes of dietary intake and blood eicosapentaenoic acid, docosahexaenoic acid, and arachidonic acid levels in Japanese men and women.

We studied the relationship between dietary intake and the blood compositions of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (ARA) in four study groups with different ages and sexes. One hundred and four subjects were recruited. Dietary records together with photographic records from 28 consecutive days were amassed and the fatty acid composition in erythrocyte membranes and plasma lipid fractions was analyzed. Fish intake in the elderly group was significantly higher than that in the young group in both men and women. The compositions of ARA in erythrocytes and plasma phospholipids in the elderly were lower than those in the young, but the ARA intake was nearly identical. In the elderly group, the percentage of dietary ARA consumed at the same time as EPA and DHA derived from fish was high. We considered that these fatty acids markedly inhibited the incorporation of dietary ARA into blood phospholipids.

Mono{hydrotris(mercaptoimidazolyl)borato} complexes of manganese(II), iron(II), cobalt(II), and nickel(II) halides.

A series of [Tm(Me)M(mu-Cl)]2 and Tm(R)MCl (Tm(R) = tris(mercaptoimidazolyl)borate; R = Me, tBu, Ph, 2,6-iPr2C6H3 (Ar); M = Mn, Fe, Co, Ni) complexes have been prepared by treatment of NaTm(Me) or LiTm(R) with an excess amount of metal(II) chlorides, MCl2. Treatment of Tm(R)MCl (R = tBu, Ph, Ar) with NaI led to a halide exchange to afford Tm(R)MI. The molecular structures of [Tm(Me)M(mu-Cl)]2 (M = Mn, Ni), [Tm(Me)Ni(mu-Br)]2, Tm(tBu)MCl (M = Fe, Co), Tm(Ph)MCl (M = Mn, Fe, Co, Ni), Tm(Ar)MCl (M = Mn, Fe, Co, Ni), Tm(Ph)MI (M = Mn, Co), and Tm(Ar)MI (M = Fe, Co, Ni) have been determined by X-ray crystallography. The Tm(R) ligands occupy the tripodal coordination site of the metal ions, giving a square pyramidal or trigonal bipyramidal coordination geometry for Tm(Me)M(mu-Cl)]2 and a tetrahedral geometry for the Tm(R)MCl complexes, where the S-M-S bite angles are larger than the reported N-M-N angles of the corresponding hydrotris(pyrazolyl)borate (Tp(R)) complexes. Treatment of Tm(Ph)2Fe with excess FeCl2 affords Tm(Ph)FeCl, indicating that Tm(R)2M as well as Tm(R)MCl is formed at the initial stage of the reaction between MCl2 and the Tm(R) anion.

[Survey on public health nursing education-in the comparison of nursing education courses, universities, advanced courses for public health nurse with junior nursing colleges, and public health nursing school].

PURPOSE: Changes in public health nursing education have been consideration. Theses changes include a dramatic increase in the number of public health nurses (PHNs) who have enrolled for nursing courses at university. This study was conducted to assess the current status and future of public health nursing education as perceived by teachers and students at three types of schools: universities offering nursing courses, advanced courses for PHNs with junior nursing colleges, and public health nursing schools. METHODS: Questionnaires were distributed to teachers and students by mail. The questions that were sent to teachers asked which subjects were required to become a certified PHN, which lecture methods were employed to teach public health-particularly community health assessment methods, and what was the level of awareness of the activities of PHNs. Students were asked about their motivation to be a PHN, their understanding of public health, their views of public health activities and their images of PHNs. RESULTS: Responses were analyzed and differences between questionnaires from different schools were noted. These included the number of subjects and the total number of hours spent doing practical training and field experience in universities and the other types of schools, and the number of teachers. Differences also were noted among students at three types of schools about their age, methods of public health activities, knowledge about activities undertaken by PHNs, and their images of PHNs. No differences were observed among the schools with respect to the students' conceptual understanding of public health. CONCLUSION: Student age, practical training and field experience were found to contribute to their level of understanding of public health and public health nursing. It is thus necessary to consider the teaching methods employed by universities that administer nursing courses and the effectiveness of courses offered by graduate schools.