Analysis of vibratory feeding where the track has directional friction characteristics

This paper treats the influence of directional friction characteristics on the performance of a newly-developed vibratory feeder. It is found that, when a particle is fed without hopping on a vibratory surface, its motion can be classified into seven modes and that these modes can be defined by two dimensionless quantities similar to those obtained in conventional vibratory feeding. These dimensionless quantities are functions of the coefficient of friction, the inclination of the feed track, the frequency of vibration, the amplitude of vibration and gravitational acceleration. It is found that the non-dimensional conveying velocity can be defined as the function of four dimensionless quantities. The relations between conveying velocity and feeding conditions are derived and presented in diagrammatic form. The theoretical results show that the conveying velocity obtained with the newly-developed feeder should be considerably higher than that of a conventional feeder; these finding are supported by experimental results.     

Chemical force microscopy of self-assembled monolayers on sputtered gold films patterned by phase separation

Patterned self-assembled monolayers (SAMs) were formed on gold films and observed by friction force microscopy (FFM) and adhesive force mapping with pulsed-force mode atomic force microscopy (PFM-AFM). The substrate gold films were prepared by sputtering gold on flat surfaces of osmium-coated cover glass with surface roughness, Ra, of 0.3 nm. The patterned samples with the CH3 and COOH terminated regions were prepared using the Langmuir-Blodgett (LB) method, partial removal of the LB film by ultrasonication, and SAM formation. The CH3 and COOH terminated regions of the patterned SAMs in air and in water were observed by mapping friction and adhesive forces with FFM and PFM-AFM, respectively, using gold-coated AFM tips chemically modified with a thiol compound terminating in CH3 or COOH. The adhesive forces measured in air increased in the order of CH3/CH3, CH3/COOH (or COOH/CH3) and COOH/COOH, while those in water increased in reverse order. The enormous high adhesive force observed in water for CH3/CH3 was attributed to hydrophobic interaction between the CH3 tip and the CH3 terminated sample surface. With CH3 tip, the lower friction force was observed, however, in water on the CH3 terminated region than on the COOH terminated region. This experimental finding raises a question as to what is the effective normal load in friction measurements in water.     

Neutrophil Elastase Deficiency Ameliorates Myocardial Injury Post Myocardial Infarction in Mice

Neutrophils are recruited into the heart at an early stage following a myocardial infarction (MI). These secrete several proteases, one of them being neutrophil elastase (NE), which promotes inflammatory responses in several disease models. It has been shown that there is an increase in NE activity in patients with MI; however, the role of NE in MI remains unclear. Therefore, the present study aimed to investigate the role of NE in the pathogenesis of MI in mice. NE expression peaked on day 1 in the infarcted hearts. In addition, NE deficiency improved survival and cardiac function post-MI, limiting fibrosis in the noninfarcted myocardium. Sivelestat, an NE inhibitor, also improved survival and cardiac function post-MI. Flow cytometric analysis showed that the numbers of heart-infiltrating neutrophils and inflammatory macrophages (CD11b⁺F4/80⁺CD206^low cells) were significantly lower in NE-deficient mice than in wild-type (WT) mice. At the border zone between intact and necrotic areas, the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells was lower in NE-deficient mice than in WT mice. Western blot analyses revealed that the expression levels of insulin receptor substrate 1 and phosphorylation of Akt were significantly upregulated in NE-knockout mouse hearts, indicating that NE deficiency might improve cardiac survival by upregulating insulin/Akt signaling post-MI. Thus, NE may enhance myocardial injury by inducing an excessive inflammatory response and suppressing Akt signaling in cardiomyocytes. Inhibition of NE might serve as a novel therapeutic target in the treatment of MI.     

Magnetic Concentration of Platinum Group Metals from Catalyst Scraps Using Iron Deposition Pretreatment

Spent automobile catalysts are the most important secondary source of platinum group metals (PGMs). However, effective recovery of PGMs from catalyst scraps is difficult because they are present in only small quantities as chemically stable substances. In this study, in order to improve the efficiency of the existing recycling processes, the authors experimentally investigated a novel physical concentration pretreatment process for PGMs using samples that simulate an automobile catalyst. In order to magnetically separate PGMs directly from the catalysts, ferromagnetic Fe was deposited on the PGM particles (or the porous catalyst layer) using an electroless plating technique. By using a plating bath containing sodium borohydride and potassium sodium tartrate as the reducing and complexing agents, respectively, Fe was successfully deposited on the sample without requiring complicated pretreatments such as sensitization and activation. After Fe deposition and subsequent pulverization, the PGMs could be extracted and concentrated in the form of magnetic powder using a magnet. The proposed magnetic concentration process was demonstrated to be feasible, and it has the potential to make the recycling of PGMs more efficient and environmentally friendly.     

Dynamic Behavior of Surface-Adsorbed Molecules Under Boundary Lubrication

Friction under boundary lubrication was measured using a pendulum-type friction machine. Long straight-chain fatty acids with even carbon numbers, amine, and alcohol were used as additives, and n-hexadecane was used as the base oil.

Effect of the temperature, chain length of additives and additive concentration were investigated.

The phenomena obtained under 373 K were as follows:

1) “Transition concentration” wherein a drastic change of friction coefficient appeared were observed.

2) “Transition concentration” of amine or alcohol solutions appeared at higher concentration than that of acid solution.

3) In “high concentration region,” the friction coefficient gradually increased with the decrease of the concentration.

4) Temperature raise caused a high friction coefficient.

5) Friction coefficient gradually decreased with an increase in chain length.

6) “Transition concentration” shifted toward low concentration with an increase in chain length.

7) No chain-matching effect was observed.

These results are explained introducing a new concept of adsorption mechanism, where both mechanical disturbance, i.e. friction, and adsorption-desorption process of molecules are taken into consideration.     

Examination of Electromagnetic Mode Propagation Characteristics in Straight and L-Section GIS Model Using FD-TD Analysis

It is an effective method of insulation accident prevention for gas-insulated switchgear (GIS) to detect a partial discharge (PD) that occurs as a preceding phenomenon for an insulation accident. Among various methods, a PD detection method based on the detection of electromagnetic emission through measurement of the UHF band (300 MHz to 3 GHz), which is relatively free of influences from external noises, is drawing attention as an effective method in terms of extensive and highly sensitive detection. This paper describes conducting EM-wave propagation analysis on GISs with L-sections using the finite difference-time domain (FD-TD) method and examining the influences of the Insertions on the propagation characteristics of EM-wave modes with comparison of straight GIS part. As a result, this study identified that, even on a straight GIS, the velocity dispersion characteristic of high-order modes resulted in a decrease in the crest value even if there is no reflection or conductor loss in the discontinuities. And that mode conversions and reflections in L-sections also resulted in a decrease in the crest value.     

Laser Beam Machining of Porous Woodceramics

Laser beam machining was tested as a practical method for machining porous woodceramics (WCS). A black carbonized layer is generally formed on the processed surface when woody materials are processed with laser beam machining. This problem does not occur on the WCS because they are burned. The processed surface temperature during laser beam machining can be estimated from the relationship between the burning temperature and C and O₂ component concentrations. Burning (scorching) on the processed surface decreases slightly as the feed speed of the workpiece increases. WCS are more easily processed with laser machining after being burned, using pulse oscillation to reduce the thermal influence.     

Inverse gas chromatographic observation of thermodynamic interaction between poly (vinylidene fluoride) and organic solvents

Summary Inverse gas chromatography (IGC) has been applied to observe the interaction between poly(vinylidene fluoride) (PVDF) and organic solvent systems under conditions approaching infinite dilution of the volatile component. The specific retention volumes (V_g ⁰) were calculated from the retention volumes of the PVDF/solvent systems. The retention diagrams (RDs) which were plotted as ln V_g ⁰ vs. reciprocal temperature, corresponded with the thermodynamic behavior of PVDF. PVDF dissolves well in carbonyl-containing solvents at high temperatures. In these systems, the solution is converted easily to a thermoreversible gel by standing at room temperature. The Flory-Huggins interaction parameter (χ₁₂) and molar heat of sorption of probe absorbed by the amorphous part of PVDF (Δ H₁ ^s) calculated from the retention values indicated that the characteristics of the interaction between PVDF and the solvent (probe) varied with temperature and probe properties. The results of IGC of PVDF/solvent systems were discussed in relation to the dissolution and gelation behavior of PVDF. Received: 29 September 1999/Revised version: 30 November 1999/Accepted: 9 December 1999     

Damage detection in holed composite laminates using an embedded FBG sensor

This paper discusses damage detection in a holed CFRP laminate under static and cyclic loading using an embedded fiber Bragg grating (FBG) sensor. In order to detect the damage extension in the laminate, the change in the spectrum shape was measured using an embedded FBG sensor and was compared with that obtained by numerical simulation. The shape of the reflection spectrum did not change during the cyclic load test; however, it did change with increased strain in the static load test, due to damage around the hole. To clarify this difference, the polished surface of the cross section of the specimen was analyzed. Debonding was observed between the optical fiber and matrix during the cyclic load test. These results lead us to conclude that fatigue damage around a hole in a composite laminate may not be detected with an FBG sensor due to the debondings.