Synthesis of Highly Substituted Imidazo[1,5‐a]quinoxalines Through a Multicomponent Reaction Followed by Deprotection–Cyclization

An operationally simple and efficient, one‐pot, two‐step methodology has been developed for the assembly of medicinally important imidazo[1,5‐a]quinoxalines. The protocol involves the multicomponent reaction of aryl aldehydes, ortho‐N‐Boc‐phenylenediamines and azidochalcones in the presence of erbium triflate as a Lewis acid catalyst, followed by deprotection–cyclization with 10% trifluoroacetic acid, furnishing the desired compounds in moderate to good yields. By virtue of their convergence, two aromatic rings and four new bonds are generated during the course of this reaction protocol. The structure of one of the compounds was proved by X‐ray crystallography.

     

Effect of ureolytic bacteria on concrete properties

Bacteria are incredibly diverse. Numerous diverse bacterial species participate in the precipitation of mineral carbonates in various natural environments, including soils, geological formations, freshwater biofilms, oceans and saline lakes.Bacteria are believed to affect carbonate precipitation both through affecting local geochemical conditions and by serving as potential, nucleation sites for mineral formation. A novel technique for the remediation of damaged structural formations has been developed by employing a selective microbial plugging process, in which metabolic activities promote precipitation of calcium carbonate in the form of calcite. Recently, microbial mineral precipitation resulting from metabolic activities of some specific microorganisms in concrete to improve the overall behavior of concrete has become an important area of research. It has been hypothesized that almost all bacteria are capable of CaCO₃ production because precipitation occurs as a byproduct of common metabolic processes such as photosynthesis, sulfate reduction, and urea hydrolysis.In this review paper, an overview of bacteria, their types based on the classification has been studied. Even the effect of bacteria on various parameters in concrete proves to be beneficial development. Based on the studied properties like compressive strength, permeability, water absorption, chloride ingression, the microbial mineral precipitation appears to be a promising technique at this state of development.     

Evaluation of the use of the Chebyshev algorithm with the quadrature method of moments for simulating aerosol dynamics

The quadrature method of moments (QMOM) has been widely used for the simulation of the evolution of moments of the aerosol general dynamic equations. However, there are several shortcomings in a crucial component of the method, the product-difference (P-D) algorithm. The P-D algorithm is used to compute the quadrature points and weights from the moments of an unknown distribution. The algorithm does not work for all types of distributions or for even reasonably high-order quadrature. In this work, we investigate the use of the Chebyshev algorithm and show that it is more robust than the P-D algorithm and can be used for a wider class of problems. The algorithm can also be used in a number of applications, where accurate computations of weighted integrals are required. We also illustrate the use of QMOM with the Chebyshev algorithm to solve several problems in aerosol science that could not be solved using the P-D algorithm.     

Ferroelectric Phase Stability Studies in Spray Deposited KNO3:PVA Composite Films

The composite films of potassium nitrate (KNO₃):poly(vinyl alcohol) (PVA) have been prepared at different temperatures by spray-deposition technique. Ferroelectric hysteresis loops were traced at room temperature for the composite films using modified Sawyer and Tower circuit. The X-ray diffraction studies confirm the existence of ferroelectric phase III of KNO₃ in the composite films at the room temperature, where this phase in pure KNO₃ films is known to exist in the temperature range 110°–124°C. The composite films deposited at 200°C shows the optimum remanent polarization, P _r∼17 μC/cm². The P _r was studied in the frequency range 10 Hz–1 kHz. The stability of the P _r in the composite films exhibits improved fatigue compared with that of quenched KNO₃ films. The capacitance–voltage ( C – V ) characteristics exhibits butterfly features which supports the presence of ferroelectric phase in the composite films. The atomic force microscopy images show that the composite films have uniform dispersion of KNO₃ particles in the PVA matrix.     

Integral transform methods for inverse problem of heat conduction with known boundary of a thin rectangular object and its stresses

The three-dimensional inverse transient thermoelastic problem for a thin rectangular object is considered within the context of the theory of generalized thermoelasticity. The upper surface of the rectangular object occupying the space D: a≤x≤a; b≤y≤b; 0≤z≤h; with the known boundary conditions. Laplace and Finite Marchi-Fasulo transform techniques are used to determine the unknown temperature, temperature distribution, displacement and thermal stresses on upper plane surface of a thin rectangular object. The distributions of the considered physical variables are obtained and represented graphically.     

Assessment of proteolysis in ultra‐high temperature milk using attenuated total reflectance–Fourier transform infrared spectroscopy

This study investigated the suitability of attenuated total reflectance–Fourier transform infrared spectroscopy (ATR‐FTIR) as an alternative technique to assess proteolysis in ultra‐high temperature (UHT) milk. Commercial UHT milk samples were stored (5 and 30 °C) and analysed for four months. Milk samples were treated with acetic acid and trichloroacetic acid to obtain milk extracts containing peptides. The concentrated extracts were subjected to ATR‐FTIR, and the spectrum was obtained. Results were compared with techniques like high‐performance liquid chromatography, fluorescamine and 2,4,6‐trinitrobenzenesulphonic acid. The present study indicated that ATR‐FTIR‐based method can be used as an alternative method for assessing proteolysis in UHT milk.     

Computer simulation of membrane processes: ultrafiltration and dialysis units

An algorithm for computer simulation of membrane processes such as ultrafiltration and dialysis has been developed using a simplified finite volume approach. The technique used is slightly different from the standard finite difference, finite volume and finite element methods where all the parameters are considered at fixed nodal points. In the present approach the entire flow chamber is divided into a large number of volume elements and each element is considered to be an independent unit (similar to finite volume method). All mass flux and velocity components are calculated at the boundaries whereas concentration is considered at the center of the element. Thus, unlike FDM, FVM, and FEM, in the present approach nodal points for velocity and concentration are different. It has been observed that this method is more accurate and fast and requires less computational effort.     

Development of a near activity visual questionnaire to assess accommodating intraocular lenses.

PURPOSE: To develop a questionnaire that subjectively assesses near visual function in patients with 'accommodating' intraocular lenses (IOLs). METHODS: A literature search of existing vision-related quality-of-life instruments identified all questions relating to near visual tasks. Questions were combined if repeated in multiple instruments. Further relevant questions were added and item interpretation confirmed through multidisciplinary consultation and focus groups. A preliminary 19-item questionnaire was presented to 22 subjects at their 4-week visit post first eye phacoemulsification with 'accommodative' IOL implantation, and again 6 and 12 weeks post-operatively. Rasch Analysis, Frequency of Endorsement, and tests of normality (skew and kurtosis) were used to reduce the instrument. Cronbach's alpha and test-retest reliability (intraclass correlation coefficient, ICC) were determined for the final questionnaire. Construct validity was obtained by Pearson's product moment correlation (PPMC) of questionnaire scores to reading acuity (RA) and to Critical Print Size (CPS) reading speed. Criterion validity was obtained by receiver operating characteristic (ROC) curve analysis and dimensionality of the questionnaire was assessed by factor analysis. RESULTS: Rasch Analysis eliminated nine items due to poor fit statistics. The final items have good separation (2.55), internal consistency (Cronbach's alpha=0.97) and test-retest reliability (ICC=0.66). PPMC of questionnaire scores with RA was 0.33, and with CPS reading speed was 0.08. Area under the ROC curve was 0.88 and Factor Analysis revealed one principal factor. CONCLUSION: The pilot data indicates the questionnaire to be internally consistent, reliable and a valid instrument that could be useful for assessing near visual function in patients with 'accommodating' IOLS. The questionnaire will now be expanded to include other types of presbyopic correction.     

Antifertility effects of neem (Azadirachta indica) oil in male rats by single intra-vas administration: an alternate approach to vasectomy

An alternate approach to vasectomy for long-term male contraception following a single intra-vas application of a traditional plant (Azadirachta indica) product having immunomodulatory properties is described. Male Wistar rats of proven fertility were given a single dose (50 microliters) of neem oil in the lumen of the vas deferens on each side; control animals received the same volume of peanut oil. Animals were put on continuous mating 4 weeks after the treatment, with females of proven fertility. While the control animals impregnated the female partners, all males treated with neem oil remained infertile throughout the 8 months of observation period. Epididymal and vas histology were normal without any inflammatory changes or obstruction. The intra-vas administration of neem oil resulted in a block of spermatogenesis without affecting testosterone production; the seminiferous tubules, although reduced in diameter, appeared normal and contained mostly early spermatogenic cells. No anti-sperm antibody could be detected in the serum. Unilateral administration of neem oil in the vas resulted in a significant reduction of testicular size and spermatogenic block only on the side of application; the draining lymph node cells of the treated side also showed enhanced proliferative response to in vitro mitogen challenge. These results indicate that the testicular effects following intra-vas application of neem oil may possibly be mediated by a local immune mechanism.     

Study of optoelectronic properties of Michler's ketone/Cd(S,Se):Cu double layer system for electrophotographic applications

Xerographic properties of the double layer system consisting of Michler's ketone (tetramethyl diaminodiphenyl ketone) pigment—resin layer as the charge storage layer with an overlayer of photoactive Cd(S, Se): Cu as the top layer, have been investigated. The experiment shows that the charge carriers generated in Cd(S, Se):Cu could be injected into and transported through the Michler's ketone pigment—resin layer. Acceptance potential, fractional dark and photo-induced decrease, contrast potential and the relative spectral sensitivity are the important xerographic characteristics studied. The double layer shows a maximum surface potential of 844 V and 99.7% fractional decay of surface potential under illumination as calculated 10 sec after the start of illumination. The spectral sensitivity peaks of the system lie at 484, 534 and 591 nm in the visible region.