Degradation of a model naphthenic acid, cyclohexanoic acid, by vacuum UV (172 nm) and UV (254 nm)/H2O2

The mechanism of hydroxyl radical initiated degradation of a typical oil sands process water (OSPW) alicyclic carboxylic acid was studied using cyclohexanoic acid (CHA) as a model compound. By use of vacuum ultraviolet irradiation (VUV, 172 nm) and ultraviolet irradiation in the presence of hydrogen peroxide UV(254 nm)/H(2)O(2), it was established that CHA undergoes degradation through a peroxyl radical. In both processes the decay of the peroxyl radical leads predominantly to the formation of 4-oxo-CHA, and minor amounts of hydroxy-CHA (detected only in UV/H(2)O(2)). In UV/H(2)O(2), additional 4-oxo-CHA may also have been formed by direct reaction of the oxyl radical with H(2)O(2). The oxyl radical can be formed during decay of the peroxyl-CHA radical or reaction of hydroxy-CHA with hydroxyl radical. Oxo- and hydroxy-CHA further degraded to various dihydroxy-CHAs. Scission of the cyclohexane ring was also observed, on the basis of the observation of acyclic byproducts including heptadioic acid and various short-chain carboxylic acids. Overall, the hydroxyl radical induced degradation of CHA proceeded through several steps, involving more than one hydroxyl radical reaction, thus efficiency of the UV/H(2)O(2) reaction will depend on the rate of generation of hydroxyl radical throughout the process. In real applications to OSPW, concentrations of H(2)O(2) will need to be carefully optimized and the environmental fate and effects of the various degradation products of naphthenic acids considered.     

Advanced vapor recognition materials for selective and fast responsive surface acoustic wave sensors: A review

The necessity of selectively detecting various organic vapors is primitive not only with respect to regular environmental and industrial hazard monitoring, but also in detecting explosives to combat terrorism and for defense applications. Today, the huge arsenal of micro-sensors has revolutionized the traditional methods of analysis by, e.g. replacing expensive laboratory equipment, and has made the remote screening of atmospheric threats possible. Surface acoustic wave (SAW) sensors – based on piezoelectric crystal resonators – are extremely sensitive to even very small perturbations in the external atmosphere, because the energy associated with the acoustic waves is confined to the crystal surface. Combined with suitably designed molecular recognition materials SAW devices could develop into highly selective and fast responsive miniaturized sensors, which are capable of continuously monitoring a specific organic gas, preferably in the sub-ppm regime. For this purpose, different types of recognition layers ranging from nanostructured metal oxides and carbons to pristine or molecularly imprinted polymers and self-assembled monolayers have been applied in the past decade. We present a critical review of the recent developments in nano- and micro-engineered synthetic recognition materials predominantly used for SAW-based organic vapor sensors. Besides highlighting their potential to realize real-time vapor sensing, their limitations and future perspectives are also discussed.     

A Novel Thermal Knoevenacel Condensation via A Thermal Michael Reaction

In connection with the total synthesis of natural products by retro-mass spectral approach,^1–3 the thermal reaction between 6,7-dimethoxy-3-isochromanone 1 and benzalmalononitrile 3 was studied. The Knoevenagel condensation product⁴ was obtained over and above the expected Diels-Alder adduct. The scope, limitation and mechanism of the aforesaid unusual thermal Knoevenagel condensation through a thermal Michael reaction is described.     

Synthesis and structural studies of early transition metalloporphyrin complexes. 1. X-ray structures of meso-5,10,15,20 tetratolyl hafnium(IV) μ-dioxo dimer complex and meso-5,10,15,20 tetratolyl porphyrin vanadium(IV) oxo complex

Abstract

(TTP) hafnium dichloride, 1, where TTP = meso-5,10,15,20 tetratolyl porphyrin dianion, has been synthesized and spectroscopically characterized as a precursor to 2. Hydrolysis of 1 gives (TTP) hafnium μ-dioxo dimer, 2. (TTP) vanadium oxo complex, 3, can be obtained by hydrolysis of the corresponding chloro complex. Compound 2 has been characterized by spectroscopic and single crystal X-ray diffraction analyses. [(TTP)HfO]₂-toluene crystalizes in the space group C2/c, a = 31.906(6) Å, b = 16.864(3) Å, c = 19.180(4) Å, β = 117.52(3)°, V = 9152(3) ų, d_calcd = 1.369 g/cm³, Z = 8, 6029 unique observed reflections, final R = 0.077. The Hf atom is 1.02 Å from the plane of the porphyrin ring; Hf-O bond lengths are 2.1 Å. The hafnium atoms are 3.06(1) Å from each other and the average Hf-O-Hf angle is 94°. The porphyrin rings are 5.4° from being parallel and the distance between the centers of the porphyrin rings is ～ 5.1 Å. TTPVO·mesitylene, 3, crystallizes from mesitylene in the space group P1, a = 8.365(2), b = 10.320(3), c = 14.380(5) Å, α = 91.91(3), β = 91.44(3), γ = 108.26(2)°, V = 1177.2(6) ų, d_calcd = 1.27 g/cm³, Z = 1, 1851 observed unique reflections, final R = 0.069. The average V - N distance = 2.016 Å. The coordination geometry around the vanadium is distorted C_4V. The V = O group is disordered about the center of inversion. The vanadium atom resides 0.57 Å above the plane of the nitrogens. The (ring center) -V = O angle is 165.9° while the V = O vector is essentially colinear with the vector normal to the plane of nitrogens.     

On the importance of mathematical play

A number of existing theories and proposals for the meaning and characteristics of ‘play’ are considered before the authors suggest six characteristics of mathematical play, including the idea that it is not confined to childhood. Previous studies provide evidence for relating play to cognitive gain while the place of mathematical play in research activities is illustrated by describing a mathematician's approach to a number investigation from the classroom-The Six Circles. The problem-solving process for the Six Circles and observations of students solving calculator and integration problems are analysed in relation to theories of play and cognitive gain and also considered from the perspective of the students' experience. Piaget's theory for the assimilation and accommodation of new information and Davis's view of play as ‘space to support learning’ are reflected in the authors' rationale for suggesting that open questions and mathematical play provide opportunities for students to develop their own conjectures, with no threat of failure, and provide a foundation for mathematical learning. Some difficulties of implementing a ‘play’ approach in the classroom are discussed and further research questions proposed.     

Ultrasonic decontamination of prototype fast breeder reactor fuel pins

Fuel pin decontamination is the process of removing particulates of radioactive material from its exterior surface. It is an important process step in nuclear fuel fabrication. It assumes more significance with plutonium bearing fuel known to be highly radio-toxic owing to its relatively longer biological half life and shorter radiological half life. Release of even minute quantity of plutonium oxide powder in the atmosphere during its handling can cause alarming air borne activity and may pose a severe health hazard to personnel working in the vicinity. Decontamination of fuel pins post pellet loading operation is thus mandatory before they are removed from the glove box for further processing and assembly. This paper describes the setting up of ultrasonic decontamination process, installed inside a custom built fume-hood in the production line, comprising of a cleaning tank with transducers, heaters, pin handling device and water filtration system and its application in cleaning of fuel pins for prototype fast breeder reactor. The cleaning process yielded a typical decontamination efficiency of more than 99%.     

Exact solution of electroosmotic flow in generalized Burgers fluid

An exact solution is developed for the time periodic electroosmotic flow of a non-Newtonian fluid between the micro-parallel plates. The constitutive equations of a generalized Burgers fluid are used in the mathematical formulation. The resulting problem is solved by a Fourier transform technique. Graphs are plotted and discussed for various emerging parameters of interest.     

Synthesis, <Emphasis Type="Italic">Spectrofluorometric</Emphasis> Studies,Micellization and non Linear Optical Properties of Blue Emitting Quinoline (AMQC) Dye

Blue emitting 2-amino-4-(3, 4, 5-tri methoxyphenyl)-9-methoxy-5,6 dihydrobenzo[f]isoquinoline-1-carbonitrile (AMQC) dye was synthesized by one-pot multicomponent reactions (MCRs) of 3,4,5-trimethoxybenzaldehyd, malononitrile, 6-methoxy-1,2,3,4-tetrahydro-naphthalin-1-one and ammonium acetate. Results obtained from spectroscopic and elemental analysis of synthesized AMQC was in good agreement with their chemical structures. Fluorescence polarity study demonstrated that AMQC was sensitive to the polarity of the microenvironment provided by different solvents. In addition, spectroscopic and physicochemical parameters, including electronic absorption, excitation coefficient, stokes shift, oscillator strength, transition dipole moment and fluorescence quantum yield were investigated in order to explore the analytical potential of AMQC. Dye undergoes solubilization in different micelles and may be used as a quencher and a probe to determine the critical micelle concentration (CMC) of SDS and CTAB. Nonlinear optical parameters of AMQC dye shows relatively lower nonlinear refractive index and nonlinear absorption coefficient at the power levels. Variation of n₂ with concentration is linear in the concentration range used in the present study.     

Design,Synthesis, and In Vitro Evaluation of Novel Indolyl DiHydropyrazole Derivatives as Potential Anticancer Agents

Indoles derived from both natural sources or artificial synthetic methods have been known to interact with aryl hydrocarbon receptors (AhR), and exhibit anticancer activity. In light of these attractive properties, a series of hybrid molecules with structural features of indoles, i.e., those bearing a pyrazoline nucleus, were evaluated for their enhanced anticancer activity. The designed molecules were subjected to molecular docking in order to screen for potential AhR interacting compounds, and the identified indolyl dihydropyrazole derivatives were synthesized. The synthesized compounds were characterized, and their cytotoxicity was evaluated against four human cancer cell lines using the MTT assay. Based on the Glide g-score, H-bonding interactions and bonding energy of 20 candidate molecules were selected for further analysis from the 64 initially designed molecules. These candidate molecules have shown promising anti-proliferative activity against the cell lines tested. Among these candidate molecules, the compounds with hydroxy phenyl substitution on the pyrazoline ring have shown potent activity across all the tested cell lines. The designed scaffold was proven effective for screening potential candidate molecules with anticancer properties, and may be further optimized structurally for yielding the ideal anti-tumorigenic compound for the treatment of various cancers.