Insights into the Catalytic Activity of Nitridated Fibrous Silica (KCC‐1) Nanocatalysts from 15N and 29Si NMR Spectroscopy Enhanced by Dynamic Nuclear Polarization

Fibrous nanosilica (KCC‐1) oxynitrides are promising solid‐base catalysts. Paradoxically, when their nitrogen content increases, their catalytic activity decreases. This counterintuitive observation is explained here for the first time using ¹⁵N‐solid‐state NMR spectroscopy enhanced by dynamic nuclear polarization.     

Calorimetric study of Sb-modified Ge–Se–Te glassy alloys

The glassy compositions of Ge ₁₆ Se ₅₂ Te _32?x Sb _x system, obtained using rapid melt quenching technique, have been characterized by calorimetric study at different heating rates in this study. A systematic investigation of the crystallization kinetics is carried out for these compositions. Composition corresponding to atomic % 8 of Sb has good thermal stability. The material exhibits the unique thermal properties, which makes it suitable to use for electrical or memory switching devices. Various thermal parameters, activation energies of glass transition and crystallization are calculated using relevant approaches.     

Synthesis and Antimicrobial Activities of Novel Series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one Derivatives

In the present investigation, a novel series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one derivatives were synthesized by condensation of 2‐substituted‐4‐methylthiazole‐5‐carbaldehyde with 4‐(2‐substituted thiazol‐4‐yl)benzenamine followed by cyclo‐condensation with thioglycolic acid in toluene. All the newly synthesized compounds were characterized by spectral (IR, ¹H NMR, ¹³C NMR, and Mass) methods. The title compounds were screened for quantitative antibacterial activity (minimal inhibitory concentration). All compounds 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h and 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h show moderate to good antimicrobial activity, whereas compounds ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h ) also show moderate antifungal activity.     

Quantitative analysis of slurry sample by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) has been employed for the analysis of slurry samples. Quantitative analysis of slurry samples is crucial and challenging. The problems associated with slurry samples include splashing, surface turbulence, and the difficulties of obtaining reproducible samples due to sedimentation. The LIBS analysis has achieved limited success due to inherent disadvantages when applied to slurry samples. In order to achieve improved measurement precision and accuracy, a spin-on-glass sampling method was evaluated. Five elements (Al, Ca, Fe, Ni, and Si) were examined in five slurry simulants containing varying amounts of each ion. Three calibration models were developed by using univariate calibration, multiple linear regression, and partial least square regression. LIBS analysis results obtained from the partial least square regression model were determined to be the best fit to results obtained from inductively coupled plasma optical emission spectroscopy analysis.     

Scaling laws for gas-solid riser flow through two-fluid model simulation

Scale up of gas-solid circulating fluidized bed (CFB) risers poses many challenges to researchers.In this paper,CFD investigation of hydrodynamic scaling laws for gas-solid riser flow was attempted on the basis of two-fluid model simulations,in particular,the recently developed empirical scaling law of Qi,Zhu,and Huang (2008).A 3D computational model with periodic boundaries was used to perform numerical experiments and to study the effect of various system and operating parameters in hydrodynamic scaling o...     

Greener and rapid access to bio-active heterocycles: room temperature synthesis of pyrazoles and diazepines in aqueous medium

An expeditious room temperature synthesis of pyrazoles and diazepines by condensation of hydrazines/hydrazides and diamines with various 1,3-diketones is described. This greener protocol was catalyzed by polystyrene supported sulfonic acid (PSSA) and proceeded efficiently in water in the absence of any organic solvent within 1-2 min.     

Large deflection of thin plates in cylindrical bending – Non-unique solutions

Considered in this paper is the large deflection of a thin beam. One end of the beam is fixed (clamped) to a rigid wall, while the other end is placed on a flat surface of arbitrary orientation. It is shown that under certain conditions, the solution to the deflected shape of the plate is not unique. Conditions for the existence of multiple solutions are identified. Numerical methodologies are developed to obtain the multiple solutions. Experiments were conducted to verify the numerical predictions. Excellent agreements are found between the predicted deflection and the experimental measurements.     

A remark on control of partially observed Markov chains

A new state variable is introduced for the problem of controlling a Markov chain under partial observations, which, under a suitably altered probability measure, has a simple evolution.