Effect of velocity slip in axially undefined porous bearings

A theoretical analysis of the performance characteristics of axially undefined journal bearings was carried out. The analysis takes into account the velocity slip at the surface of the porous medium by using the Beavers-Joseph criterion. Results are presented for various bearing characteristics and compared with earlier results obtained by using the no-slip condition.     

Copper‐Catalyzed C–N,C–O Coupling Reaction of Arylglyoxylic Acids with Isatins

The copper(II)‐catalyzed decarboxylative coupling reactions of arylglyoxylic acids with isatins afford 4H‐benzo[d][1,3]oxazin‐4‐ones via decarbonylation and concurrent C–N, C–O bond formation.

     

Iron(III)-mediated ATRP systems of n-docosyl acrylate with AIBN and BPO

Well-defined poly(n-docosyl acrylate) (PDA) with narrow molecular weight distribution has been synthesized by atom transfer radical polymerization (ATRP) and reverse ATRP of n-docosyl acrylate (DA) at 80 °C in N,N-dimethylformamide using the carbon tetrabromide/FeCl₃/2,2′-bipyridine (bpy) initiation system in the presence of 2,2′-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) as the source of reducing agent. The rates of polymerization for both the systems exhibit first-order kinetics with respect to the monomer, however, peroxide-initiated system shows slow rate of polymerization as compared to the azo-system. The effect of various reaction parameters on number average molecular weight (M _n ) and molecular weight distribution (M _w/M _n ) have been investigated. The resulting PDA that obtained in presence of AIBN and BPO systems has been compared for both the conventional and reverse ATRP. The reverse ATRP initiated by peroxides behaves differently than that of the azo initiators. In reverse ATRP with BPO, the rate of polymerization (R _p) has been significantly increased with the increase of BPO resulting higher M _n and broader M _w/M _n . The reverse ATRP of DA did not exhibit living characteristics with BPO system. PDA has been characterized by GPC, FTIR, and NMR spectroscopy.     

Modal analysis of prestressed draft pad of freight wagons using finite element method

The present work intends to investigate dynamic behaviour of draft gear using finite element method. The longitudinal force that the draft gear absorbs usually leads to the failure of its components, especially, the load bearing draft pads. Dynamic behaviour of an individual draft pad and a draft gear is determined and characterized with exciting frequencies and corresponding mode shapes. The effect of compressive prestress load on the dynamic behaviour of an individual draft pad is also determined as the draft pads in assembled state are under constant axial compressive force in the draft gear. The vibration characteristics of individual draft pad are compared with draft pads that are part of draft gear. The modal analysis gives us a basis for subjecting a draft pad to higher frequency loading for determining its fatigue behaviour.

     

Synthesis of Red-Light-Responsive Pheophorbide-a Tryptamine Conjugated Photosensitizers for Photodynamic Therapy

Six methyl pheophorbide-a derivatives were prepared by linking a tryptamine side chain at the C-13 ¹ , C-15 ² and C-17 ³ positions of pheophorbide-a. P repared conjugates were characterized and evaluated for their photocytotoxicity against A549 cells. The conjugate 6 a with strong absorption at 413 nm (Soret band), 663–671 nm (Q bands) and comparable fluorescence quantum yield (0.26) was found to exhibit significant cytotoxicity (659 nM). Molecular integration of pheophorbide-a and tryptamines showed synergistic effects as the most potent conjugate 6 a was identified with enhanced photocytotoxicity when compared to methyl pheophorbide-a. T he conjugate 6 a was smoothly taken up by A549 cells and exhibited intracellular localization predominantly to lysosome in the cytoplasm. Upon photoirradiation 6 a generated singlet oxygen to show potent cytotoxicity toward A549 cells.     

Destruction of chlorinated organics by hydrotreatment using Ru/TiO2 catalyst

Catalytic hydrodechlorination reactions of p‐chloro‐m‐cresol (PCMC) and p‐chloroaniline (PCA) were investigated in a slurry reactor using a Ru/TiO₂ catalyst. The organic reaction intermediates, m‐cresol and aniline, were further converted into methylcyclohexanol and cyclohexylamine respectively. Kinetics of PCMC hydrogenation was studied over the ranges in temperature, 323–373 K, H₂ partial pressure, 0.34–1.38 MPa, PCMC concentration, 3.5–14 mM and catalyst loading, 0.1–2 kg/m³. The reaction orders with respect to PCMC and H₂ were evaluated as 0.5 and 0.8 respectively. It was found that aniline hydrogenation is the rate‐determining step in the hydrotreatment of PCA. Kinetics of aniline hydrogenation was studied at 343 and 363 K over the ranges in H₂ partial pressure, 0.34–1.38 MPa, aniline concentration, 5.4–21.5 mM and catalyst loading, 0.1–0.6 kg/m³. The reaction orders with respect to aniline and H₂ were found to be 1.3 and 1.0 respectively. © 2012 Canadian Society for Chemical Engineering     

Exceptionally High Dielectric Constant in Ceramic Pr2CuO4

The pristine layered cuprate Pr₂CuO₄ samples of >95% density were fabricated as thin disks. The samples, analyzed by X‐ray diffraction and Scanning electron microscopy, showed clean T′‐type phase with Rietveld refined lattice parameters a = b = 3.95805(±5) Å and c = 12.2262(±5) Å. The measured dielectric properties of the Pr₂CuO₄ ceramics, in the temperature range ?100°C–150°C and frequencies (ν) 0.1 Hz–1 MHz, showed extremely high ε_r′ > 10⁴ (above ?30°C), and dissipation (tan δ = ε_r′′/ε_r′) between 0.1 and 5 (for 500 Hz ≤ ν ≤ 1 MHz, and ?100 ≤ T ≤ 150°C). The ac conductivity of Pr₂CuO₄ ceramics ranged between 10^?6 and 10^?3 Scm^?1 for the measured frequencies and temperatures, and showed frequency‐dependent double power law behavior akin to a modified Jonscher's power law.