ABSTRACT
A binder plays a critical role in dispersion of coating liquids and the quality of coating. Poly(vinylidene fluoride) (PVDF) is widely used as a binder in cathode slurries; however, its role as a binder is still under debate. In this paper, we study the role of PVDF on the rheology of cathode battery slurries consisting of Li(Ni1/3Mn1/3Co1/3)O2 (NCM), carbon black (CB) and N-methyl-2-pyrrolidone (NMP). Rheology and microstructure of cathode slurries are systemically investigated with three model suspensions: CB/PVDF/NMP, NCM/PVDF/NMP and NCM/CB/PVDF/NMP. To highlight the role of PVDF in cathode slurries, we prepare the same model suspensions by replacing PVDF with PVP, and we compare the role of PVDF to PVP in the suspension rheology. We find that PVDF adsorbs neither onto NCM nor CB surface, which can be attributed to its poor affinity to NCM and CB. Rheological measurements suggest that PVDF mainly increases matrix viscosity in the suspension without affecting the microstructure formed by CB and NCM particles. In contrast to PVDF, PVP stabilizes the structure of CB and NCM in the model suspensions, as it is adsorbed on the CB surface. This study will provide a useful insight to fundamentally understand the rheology of cathode slurries.
ABSTRACT
We explore the relaxation behavior of model colloidal gels under steady shear flow by means of orthogonal superposition rheometry. Fumed silica and carbon black dispersions in Newtonian matrices are used as a model system. As shear rate increases, the frequency dependent orthogonal moduli of the gels shift along the frequency axis without changing their shape, which finally can be superimposed to yield a single master curve. This indicates that the shear rate tunes a master clock for overall relaxation modes in the sheared colloidal gels to produce a "time-shear rate superposition (TSS)", as temperature does in polymeric liquids to produce a time-temperature superposition (TTS). The horizontal shift factor required at each shear rate to obtain the master curve is found to be directly proportional to the suspension viscosity for all the cases. From this result, we suggest that the suspension viscosity determines the overall relaxation time of the particles in the flowing colloidal gel.
ABSTRACT
BACKGROUND: The microRNA (miRNA) pathway has emerged as one of the biologic pathways implicated in stem cell regulation. miRNA is a noncoding, single-stranded RNA consisting of 20-25 nucleotides that inhibits the protein production at the step of translation. The molecular effects of lidocaine and procaine on adipose stem cells were investigated by examining RNA expression array. METHODS: Adipose stem cells were isolated from a prior abdominal liposuction procedure. The human adipose stem cells were cultured and then added to a mixture of 1 ml of culture medium plus 1 ml of 2% lidocaine or 2% procaine for the duration of 30 minutes. The expression levels of miRNAs were estimated by using peptide nucleic acid (PNA)-miRNA array analysis throughout the denaturation and hybridization processes after the isolation of miRNA. The miRNAs detected by microarray that either decreased by half fold or increased by 1.5 fold from the control level were interpreted as significant. RESULTS: According to microarray analysis there were 61 miRNAs in total, and no miRNA had decreased expression levels. The stem cells treatment with lidocaine showed 4 alteration of expression with miR-9a(*) (1.53 fold), miR-29a (1.64 fold), miR-296-5p (1.64 fold) and miR-373 (1.94 fold). The stem cells treated with procaine showed 32 miRNAs that were significantly up-regulated with a range of 1.5 to 2.06 fold. They were stem cell differentiation-related miRNAs, apoptosis and cell cycle-associated miRNAs, immunity-associated miRNAs and hormonal response-related miRNAs. CONCLUSIONS: Lidocaine and procaine affect the miRNA expression on adipose stem cells and the effect of procaine is more marked than that of lidocaine.
ABSTRACT
BACKGROUND: It was well-known that smoking affects the cardiovascular system, and remifentanil can suppress the sympathetic stimulations induced by tracheal intubation. The purpose of this study was to investigate whether there was any difference in the hemodynamic changes induced by tracheal intubation with using remifentanil between smokers and nonsmokers. METHODS: EIGHTY PATIENTS WERE ENROLLED: male smokers (MS), male nonsmokers (MN), female smokers (FS) and female nonsmokers (FN). Anesthesia was induced with diluted remifentanil (20 microg/ml) at a rate of 10 microg/kg/hr using an infusion pump, and 2 min later, midazolam 0.05 mg/kg and propofol 0.8 mg/kg were injected for achieving unconsciousness. Rocuronium 1 mg/kg was used for muscle relaxation, and tracheal intubation was performed 2 min after rocuronium injection. After tracheal intubation, the remifentanil was decreased to 2 microg/kg/hr. The mean arterial pressure (MAP) and heart rate (HR) were checked before induction, on unconsciousness, just before intubation, just after intubation and 1, 2 and 3 minutes after intubation, and these values were compared between the groups. RESULTS: In men, the MAP and HR just after intubation and at 1, 2 and 3 minutes after intubation in Group MS were significantly higher than those of Group MN (P < 0.05). For the women, the HR in both groups (the FS and FN groups) were increased just after intubation and 1, 2 and 3 minutes after intubation compared with that at the baseline, respectively, but there was no difference between the two groups. CONCLUSIONS: There was a difference of the hemodynamic changes induced by tracheal intubation with using remifentanil between the male smokers and nonsmokers, but not in women.
