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Torque smoothness is an essential requirement for high-performance motor drive applications. Synchronous reluctance machines have high torque ripple due to non-linear magnetic path coupled with saturation of the rotor core segments during operation. This paper proposes an active torque ripple minimization technique for Synchronous reluctance machine using current injection. The proposed method is aimed to compensate for both cogging and torque ripple generated by the machine. The method also optimizes for the minimum magnitude of ripple injection for active cancellation. The effectiveness of the proposed method is evaluated with both simulation and experimental results.

Supplemental material, sj-pdf-1-pie-10.1177_0954408921990132 for Analysis of finishing performance in rotating magnetorheological honing process with the effect of particles motion by Sunil K Paswan and Anant K Singh in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering

In this article, we demonstrate the use of bio-conjugated 2D graphene oxide (bio-GO) nanostructure to probe breast cancer cell (SKBR3) with excellent discrimination over other types of circulating tumor cells. We distinctly observed that bio-GO nanostructure targets and bind SKBR3 cell selectively in the cell mixture. Longer incubation of SKBR3 cell with bio-GO causes Raman signal “turn off” when excited with 532 nm laser. This is attributed to penetration of the bio-GO through the plasma membrane of the cell by generating transient hole. Extraction of GO after cell digestion also support the internalization rubric of 2D graphene through cell membrane. Our experimental data with the HaCaT healthy cell line, as well as with LNCaP prostate cancer cell line clearly demonstrated that this Raman scattering assay is highly selective to SKBR3. The mechanism of selectivity and the assay’s response change have been verified and discussed utilizing fluorescence properties of GO and various other techniques. The experimental results open up a possibility of new label free Raman scattering assay, for reliable diagnosis of cancer cell lines by monitoring “turn-off” of the Raman signal from Bio-GO nanostructure.

High-surface-area silicon oxycarbide gels and glasses were synthesized from mixtures of methyldimethoxysilane (MDMS) and tetraethoxysilane (TEOS) through acidic hydrolysis and condensation. A surface area of ∼275 m2/g and an average pore size of ∼30 A was obtained for a 50% MDMS-50% TEOS glass at 800°C under a flowing argon atmosphere. The average pore size was increased by aging the precursor gels in ammonium hydroxide. The increased average pore size and the higher strength of the mesoporous gel network enhanced the surface-area stability of the glasses; in this case, surface areas >200 m2/g were retained at 1200°C under an argon atmosphere. 29Si MAS NMR spectra revealed that an oxycarbide structure was established in the mesoporous glasses obtained after pyrolysis of the aged gels. The role of carbon was demonstrated by comparing the surface-area stability of the oxycarbide glasses with that of pure silica and that of oxycarbide glasses where all the carbon groups were removed through low-temperature plasma-oxidation treatments. In the absence of carbon, the thermal stability of the surface area decreased dramatically.

Hyper Rayleigh Scattering (HRS) and absorption spectral assays using surface-modified gold nanoparticles (AuNP) have been developed for sensitive and selective detection of trivalent chromium (Cr3+) from other metal ions including hexavalent chromium (as Cr2O72−). Gold nanoparticles of 13 nm, covalently attached with 5,5’-dithio-bis-(2-nitrobenzoic acid) (AuNP-DTNBA), is used as a probe for both the absorption and HRS assays. AuNP-DTNBA is able to detect Cr3+ at 20 ppb level at pH 6.0 using absorption spectral change of the AuNP-DTNBA. Visible color change can be observed when mixed with 250 ppb of Cr3+, while there is no color change when mixed with 2 ppm level of some of the most common metal ions such as Cr2O72−, Hg2+, Ba2+, Fe3+, Pb2+, Na+, Zn2+, Cd2+, Co2+, Mn2+, Ca2+, and Ni2+. However, a color change is observed when mixed with Ni2+, Zn2+, and Cd2+ at a concentration higher than 2 ppm. The detection limit for the HRS assay is on a remarkable 25 ppt level, and there is no detectable HRS signal at 2 ppm level for Cr2O72−, Hg2+, Ba2+, Fe3+, Pb2+, Na+, Zn2+, Cd2+, Co2+, Mn2+, Ca2+, and Ni2+.

The first attempts to introduce carbon into glass date back to 1951. But up until recently, the use of carbon or carbide raw materials, and the oxidation, volatilization and decomposition that accompany high temperature melting, have limited the synthesis of true silicon oxycarbide glasses. Here, the term silicon-oxycarbide refers specifically to a carbon-containing silicate glass wherein oxygen and carbon atoms share bonds with silicon in the amorphous, network structure. Thus, there is a distinction between black glass, which contains only a second-phase dispersion of elemental carbon, and oxycarbide glasses which usually contain both network carbon and elemental carbon. In addition to exploring the unique properties and applications of these glasses, per se, they are also of interest for developing models of the residual amorphous phases in polymer-derived silicon-carbide and silicon-nitride ceramics. The application of sol/gel techniques to glass synthesis has significantly advanced the development and characterization of silicon oxycarbide glasses. In this approach, alkyl-substituted silicon alkoxides, which are molecular precursors containing oxygen and carbon functionalities on the silicon, can be hydrolyzed and condensed without decomposition or loss of the carbon functional group. A low-temperature (

In this study, the surface chemistry and structure of methyl-substituted silica gels and porous oxycarbide glasses were investigated. FTIR was used to measure the relative concentration of Si−CH3 and Si−OH as a function of the degree of methyl-substitution and the pyrolysis temperature. The gels and glasses were further heated, dehydrated or hydrated, in situ, within the FTIR spectrometer. In the temperature range of 800–850°C, high surface area oxycarbide glasses were created with no detectable surface hydroxyl groups. Oxycarbide glasses synthesized in argon at 700°C displayed a weak band for surface hydroxyl groups and reversible physisorption of water, while those synthesized at 850/900°C showed a complete absence of surface hydroxyl groups and the formation of vicinal silanols upon chemisorption of water. Isolated silanols were observed upon heat treatment in vacuum. Formation of aromatic carbon species was found to correlate with the decomposition of the methyl groups. The oxycarbide surface is quite stable to densification (presumably due to elemental carbon on the pore surfaces). In the absence of oxygen, porous silicon oxycarbide glass powders maintain surface areas >200 m2/g at 1200°C. However, oxidizing species in the atmosphere deplete the aromatic carbon species, and the glasses lose surface area.

High-surface-area silicon oxycarbide gels and glasses were synthesized from mixtures of methyldimethoxysilane (MDMS) and tetraethoxysilane (TEOS) through acidic hydrolysis and condensation. A surface area of ∼275 m2/g and an average pore size of ∼30 A was obtained for a 50% MDMS-50% TEOS glass at 800°C under a flowing argon atmosphere. The average pore size was increased by aging the precursor gels in ammonium hydroxide. The increased average pore size and the higher strength of the mesoporous gel network enhanced the surface-area stability of the glasses; in this case, surface areas >200 m2/g were retained at 1200°C under an argon atmosphere. 29Si MAS NMR spectra revealed that an oxycarbide structure was established in the mesoporous glasses obtained after pyrolysis of the aged gels. The role of carbon was demonstrated by comparing the surface-area stability of the oxycarbide glasses with that of pure silica and that of oxycarbide glasses where all the carbon groups were removed through low-temperature plasma-oxidation treatments. In the absence of carbon, the thermal stability of the surface area decreased dramatically.

Silicon oxycarbide gels and glasses were synthesized using various ratios of methyldimethoxysilane and TEOS. These gels and glasses were compared with those made from methyltrimethoxysilane and TEOS. The effect of the Si-H functionality in the methyldimethoxysilane was of primary interest. Hydrolysis and condensation processes were monitored using 1H and 29Si-NMR spectroscopy. The structures and the oxycarbide fractions of the glasses, obtained after heating the gels to 900°C in flowing argon, were investigated with 29si-MAS NMR. The total carbon and silicon contents of the glasses were determined using chemical analysis. The glasses covered the range of carbon concentration from ∼1 to 15%, while the silicon concentrations were constant at about 40%. The concentration of the oxycarbide species was enhanced in the glasses synthesized with the Si-H functionality in the precursor.