The preparation of ketene dithioacetals and thiophenes from chloropyridines containing an active methylene group

The base catalysed reaction of carbon disulphide with the active methylene groups of chloropyridines 4 and 7, followed by alkylation with reagents which also contain active methylene groups, lead to ketene dithioacetals. Further reaction with base afforded highly substituted thiophenes

Phenol degradation using 20, 300 and 520 kHz ultrasonic reactors with hydrogen peroxide, ozone and zero valent metals

The extent of phenol degradation by the advanced oxidation process in the presence of zero valent iron (ZVI) and zero valent copper (ZVC) was studied using 20, 300 and 520 kHz ultrasonic (US) reactors. Quantification of hydrogen peroxide has also been performed with an aim of investigating the efficacy of different sonochemical reactors for hydroxyl radical production. It has been observed that the 300 kHz sonochemical reactor has the maximum efficacy for hydroxyl radical production. Phenol degradation studies clearly indicate that degradation of phenol is intensified in the presence of the catalyst and hydrogen peroxide, which can be attributed to enhanced production of hydroxyl radicals in the system. Experimental data shows that with ZVI, when the reaction was subjected to 300 kHz, complete phenol removal and 37% TOC mineralization was achieved within 25 min, whereas, in the case of 20 kHz US treatment no phenol was detected after 45 min and 39% TOC mineralization was observed. This novel study also investigated the use of zero valent copper (ZVC) and results showed that with 20, 300 and 520 kHz ultrasonic rectors, phenol removal was 10–98%, however, the maximum TOC mineralization achieved was only 26%. A comparative study between hydrogen peroxide and ozone as a suitable oxidant for Fenton-like reactions in conjunction with zero valent catalysts showed that an integrated approach of US/Air/ZVC/H2O2 system works better than US/ZVC/O3 (the ZOO process)

Industrial wastewater treatment using hydrodynamic cavitation and heterogeneous advanced Fenton processing

A combination of hydrodynamic cavitation and heterogeneous advanced Fenton process (AFP) based on the use of zero valent iron as the catalyst has been investigated for the treatment of real industrial wastewater. The effect of various operating parameters such as inlet pressure, temperature, and the presence of copper windings on the extent of mineralization as measured by total organic carbon (TOC) content have been studied with the aim of maximizing the extent of degradation. It has been observed that increased pressures, higher operating temperature and the absence of copper windings are more favourable for a rapid TOC mineralization. A new approach of latent remediation has also been investigated where hydrodynamic cavitation is only used as a pre-treatment with an aim of reducing the overall cost of pollutant degradation. It has been observed that approach of latent remediation works quite well with about 50–60% removal of TOC using only minimal initial treatment by hydrodynamic cavitation

Intensification of hydroxyl radical production in sonochemical reactors

The efficacy of sonochemical reactors in chemical processing applications has been well established in the laboratory scale of operation though at a given set of operating parameters and no efforts have been directed in terms of maximizing the free radical production. In the present work, the effect of different operating parameters viz. pH, power dissipation into the system, effect of additives such as air, haloalkanes, titanium dioxide, iron and oxygen on the extent of hydroxyl radical formation in a sonochemical reactor have been investigated using salicylic acid dosimetry. Possible mechanisms for oxidation of salicylic acid in the presence of different additives have also been established. It has been observed that acidic conditions under optimized power dissipation in the presence of iron powder and oxygen result in maximum liberation of hydroxyl radicals as quantified by the kinetic rate constant for production of 2,5- and 2,3-dihydroxybenzoic acid. The study has enabled the optimization of the conditions for maximum efficacy of sonochemical reactors where free radical attack is the controlling mechanism for the chemical processing applications

Visualisation of fingermarks and grab impressions on fabrics. Part 1: gold/zinc vacuum metal deposition

Vacuum metal deposition (VMD) is a highly sensitive technique originally introduced for detecting latent fingermarks on smooth non-porous surfaces such as carrier bags, plastics and glass. The current study explores whether VMD can be used in the examination of clothing from physical and sexual assault cases in order to visualise identifiable fingermark ridge detail and/or palmar flexion crease detail, thus allowing potential areas to be indicated for DNA swabbing and/or to determine the sequence of events. Four different fabrics were utilised during this study – nylon, polyester, polycotton and cotton, along with 15 donors who ranged in their age and propensity to leave fingermarks, from good to medium to poor as determined by results obtained from test runs using paper and plastic carrier bags processed with VMD. Once samples were collected they were kept for a determined time (1, 2, 3, 4, 5, 6, 7, 14, 21 or 28 days) and then treated using the gold/zinc metal VMD process. From the results, it appears that greater ridge detail is visible on the smoother non-porous fabrics, such as nylon whereas on rougher porous fabrics, such as cotton, only empty prints and impressions, rather than any ridge details, were visible. All fabrics did however allow the development of touch marks that could be targeted for DNA taping thus potentially leading to a DNA profile and possible identification of a suspect

The partially alternating ternary sum in an associative dialgebra

The alternating ternary sum in an associative algebra, $abc - acb - bac + bca + cab - cba$, gives rise to the partially alternating ternary sum in an associative dialgebra with products $\dashv$ and $\vdash$ by making the argument $a$ the center of each term: $a \dashv b \dashv c - a \dashv c \dashv b - b \vdash a \dashv c + c \vdash a \dashv b + b \vdash c \vdash a - c \vdash b \vdash a$. We use computer algebra to determine the polynomial identities in degree $\le 9$ satisfied by this new trilinear operation. In degrees 3 and 5 we obtain $[a,b,c] + [a,c,b] \equiv 0$ and $[a,[b,c,d],e] + [a,[c,b,d],e] \equiv 0$; these identities define a new variety of partially alternating ternary algebras. We show that there is a 49-dimensional space of multilinear identities in degree 7, and we find equivalent nonlinear identities. We use the representation theory of the symmetric group to show that there are no new identities in degree 9.Comment: 14 page

Visualisation of fingermarks and grab impressions on dark fabrics using silver vacuum metal deposition

Vacuum metal deposition (VMD) involves the thermal evaporation of metal (silver) in a vacuum, resulting in a uniform layer being deposited on the specimen being treated. This paper examines the use of silver on dark fabrics, thus offering a simpler operation and more obvious colouration to that of the traditional use of gold and zinc metals which must be evaporated separately. The aim of this study was to investigate the effect of fabric type, donor, mark age and method of fingermark deposition on the quality of marks visualised using silver VMD. This was achieved by collecting fingermark deposits from fifteen donors, of both sexes and various ages, by a grab or a press method. Four different fabrics: satin, polyester, polycotton and cotton were studied over a 10 day timeline of 1, 2, 3, 4, 5, 6, 7, 14, 21 and 28 + days. It was found that satin and polyester gave the most positive results, with polyester often producing excellent ridge detail. Cotton and polycotton were less successful with no ridge detail being observed. The donors also had an observable effect on the results obtained probably due to variations in secretions produced or pressures applied during specimen collection. The age of the mark or the method of mark deposition had little influence on the results obtained. Silver VMD is a viable process for visualising marks on certain dark fabrics and has the advantage over gold/zinc VMD in that the marks visualised are light in colour which contrasts well against the dark background

A formula for the First Eigenvalue of the Dirac Operator on Compact Spin Symmetric Spaces

Let $G/K$ be a simply connected spin compact inner irreducible symmetric space, endowed with the metric induced by the Killing form of $G$ sign-changed. We give a formula for the square of the first eigenvalue of the Dirac operator in terms of a root system of $G$. As an example of application, we give the list of the first eigenvalues for the spin compact irreducible symmetric spaces endowed with a quaternion-K\"{a}hler structure

Intensification of oxidation capacity using chloroalkanes as additives in hydrodynamic and acoustic cavitation reactors

The effect of the presence and absence of the chloroalkanes, dichloromethane (CH2Cl2), chloroform (CHCl3) and carbon tetrachloride (CCl4) on the extent of oxidation of aqueous I- to I3- has been investigated in (a) a liquid whistle reactor (LWR) generating hydrodynamic cavitation and (b) an ultrasonic probe, which produces acoustic cavitation. The aim has been to examine the intensification achieved in the extent of oxidation due to the generation of additional free radicals/oxidants in the reactor as a result of the presence of chloroalkanes. It has been observed that the extent of increase in the oxidation reaction is strongly dependent on the applied pressure in the case of the LWR. Also, higher volumes of the chloroalkanes favour the intensification and the order of effectiveness is CCl4> CHCl3 > CH2Cl2. However, the results with the ultrasonic probe suggest that an optimum concentration of CH2Cl2 or CHCl3 exists beyond which there is little increase in the extent of observed intensification. For CCl4, however, no such optimum concentration was observed and the extent of increase in the rates of oxidation reaction rose with the amount of CCl4 added. Stage wise addition of the chloroalkanes was found to give marginally better results in the case of the ultrasonic probe as compared to bulk addition at the start of the run. Although CCl4 is the most effective, its toxicity and carcinogenicity may mean that CH2Cl2 and CHCl3 offer a safer viable alternative and the present work should be useful in establishing the amount of chloroalkanes required for obtaining a suitable degree of intensification

String Branchings on Complex Tori and Algebraic Representations of Generalized Krichever-Novikov Algebras

The propagation differential for bosonic strings on a complex torus with three symmetric punctures is investigated. We study deformation aspects between two point and three point differentials as well as the behaviour of the corresponding Krichever-Novikov algebras. The structure constants are calculated and from this we derive a central extension of the Krichever-Novikov algebras by means of b-c systems. The defining cocycle for this central extension deforms to the well known Virasoro cocycle for certain kinds of degenerations of the torus. AMS subject classification (1991): 17B66, 17B90, 14H52, 30F30, 81T40Comment: 11 pages, amste