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The effective dispersion of carbonaceous soot has a critical effect on the friction and wear properties and thus decreases energy waste and equipment trouble. Molecular dynamics (MD) simulation and experimental study are performed to unravel the dispersion behavior and mechanism of soot agglomerate in lubricating system with effect of dispersant concentration at various pressures and temperatures. The static, confinement and shear models were created with dispersant polyisobutylsuccinimide polyamine (pib). At static conditions, pib molecules could approach and then self-assemble on soot fragments to disperse soot agglomerate. Under confinement conditions with an external pressure imposed, soot dispersion was better than that under static conditions, and the effect of pressure was not remarkable. The best dispersion characteristic was obtained as dispersant increased to 10 wt% exceeding that the dispersants were excessive and induced their self-aggregation. Under shear conditions, 10 wt% pib molecules showed the best dispersion at both 300 K and 373 K, which is considered as a critical value for soot dispersion from the perspective of MD simulations. Finally, the tribological experiments provided a prime validation for MD simulations. The most effective lubrication occurred in 12.5 wt% sample with friction and wear reduction by 51% and 80% compared to 10 wt% sample, respectively, due to the well soot dispersion and possible friction modification of dispersants. [Display omitted] • Dispersion of carbonaceous soot is studied by MD simulation and experiment. • Dispersive and interactive mechanisms are revealed in different models. • Good soot dispersion benefits the reduction in friction and wear. [ABSTRACT FROM AUTHOR]

This paper reports a Fabry−Pérot (F–P) cavity constructed by metal–organic frameworks (MOFs) encapsulated with TiO2 nanoparticles that can achieve selective sensing of chemicals. The MOFs‐based F–P cavity is fabricated by sequentially spray‐coating TiO2 in HKUST‐1 thin films through a layer‐by‐layer deposition strategy. The bandwidth of the cavity is tuned over a broad range by adjusting the thickness and refractive index of the HKUST‐1⊃TiO2 thin films with controllable TiO2 size and concentration. Selective sensing of chemical vapors is demonstrated on the HKUST‐1⊃TiO2 cavities which are attributed to enhanced interaction between hydroxyl groups on the surface of TiO2 and the specific oxygen‐containing analytes. In addition, molecule dynamics simulation and infrared absorption spectrum characterization are conducted to elucidate the mechanism of enhanced sensing properties. Homogeneous encapsulation of functional guest pieces with smaller sizes in MOF films contributes to specific physical–chemical properties that benefit their device applications in optical communication and chemical sensing. [ABSTRACT FROM AUTHOR]

The article offers information on Disorders Related to Chronic Pain. Topics include acute warning function of physiological nociception; and number of pathophysiological changes from the periphery to the central nervous systems that manifest in specific groups of symptoms and signs indicating pathology at various levels.

Low back pain is exceptionally ubiquitous, complex, and costly. Nevertheless, lumbar spinal stenosis (LSS) with neurogenic intermittent claudication (NIC) is a frequent cause of low back and lower extremity pain. Although the phenomena and pathophisiology of lumbar spinal stenosis has been described for decades, therapeutic treatment options remain considerably limited. Current care consists of conservative measures including physical therapy, rest, medications, and epidural steroid injection therapy or invasive surgical treatment including laminectomy with or without fusion. Despite standard of care intervention, many patients are often left inadequately treated and suffer from debilitating low back and lower extremity pain as a result of lumbar spinal stenosis. Interspinous process distraction (IPD) devices were originally described in the 1950s, but technological advances, which have contributed to improved safety and efficacy, have rekindled an interest in IPD implantation. By mimicking lumbar flexion at affected levels of stenosis, it is thought these devices decompress neural structures within the neural foramina and therefore provide pain relief. X-STOP is one such device that is currently approved in the United States for the treatment of mild to moderate NIC resulting from LSS. This manuscript presents a focused review of NIC and LSS and comprehensively presents literature related to the use of the X-STOP IPD device.

Voltage-gated calcium channels (Ca(v)) 2.2 currents are potentiated by phorbol-12-myristate, 13-acetate (PMA), whereas Ca(v) 2.3 currents are increased by both PMA and acetyl-beta-methylcholine (MCh). MCh-selective sites were identified in the alpha(1) 2.3 subunit, whereas the identified PMA sites responded to both PMA and MCh (Kamatchi, G. L., Franke, R., Lynch, C., III, and Sando, J. J. (2004) J. Biol. Chem. 279, 4102-4109; Fang, H., Franke, R., Patanavanich, S., Lalvani, A., Powell, N. K., Sando, J. J., and Kamatchi, G. L. (2005) J. Biol. Chem. 280, 23559-23565). The hypothesis that PMA sites in the alpha(1) 2.2 subunit are homologous to the PMA-responsive sites in alpha(1) 2.3 subunit was tested with Ser/Thr --> Ala mutations in the alpha(1) 2.2 subunit. WT alpha(1) 2.2 or mutants were expressed in Xenopus oocytes in combination with beta1b and alpha2/delta subunits. Inward current (I(Ba)) was recorded using Ba(2+) as the charge carrier. T422A, S1757A, S2108A, or S2132A decreased the PMA response. In contrast, S425A increased the response to PMA, and thus, it was considered an inhibitory site. Replacement of each of the identified stimulatory Ser/Thr sites with Asp increased the basal current and decreased the PMA-induced enhancement, consistent with regulation by phosphorylation at these sites. Multiple mutant combinations showed (i) greater inhibition than that caused by the single Ala mutations; (ii) that enhancement observed when Thr-422 and Ser-2108 are available may be inhibited by the presence of Ser-425; and (iii) that the combination of Thr-422, Ser-2108, and either Ser-1757 or Ser-2132 can provide a greater response to PMA when Ser-425 is replaced with Ala. The homologous sites in alpha(1) 2.2 and alpha(1) 2.3 subunits seem to be functionally different. The existence of an inhibitory phosphorylation site in the I-II linker seems to be unique to the alpha(1) 2.2 subunit.