Research Publications (Applied Sciences)

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A Box-Behnken Design and Response Surface Approach for the Simultaneous Determination of Chromium (III) and (VI) Using Catalytic Differential Pulse Polarography
(ESG, 2004-09-29) Sabela, Myalowenkosi Innocent; Kanchi, Suvardhan; Ayyappa, Bathinapatla; Bisetty, Krishna
The present paper describes an optimized Box-Behnken design using a catalytic-differential pulse polarograhic technique for the simultaneous determination of chromium (III) and (VI) in wastewater samples using ammonium piperidine dithiocarbamate as a complexing agent. The optimization strategy was carried out using a two level full factorial design. The results of the experimental design were based on an analysis of variance and demonstrated that only the pH, concentrations of the buffer and the complexing agent were statistically significant throughout the experiment. The optimal values for the three variables were 8.0, 0.2 mM and 5.0 mM for pH, concentrations of the buffer and the complexing agent respectively. Under optimum experimental conditions the detection limit of the proposed method was found to be 0.0841 µg L-1 while the linear range was 1.0-10.0 and 0.5-25.0 µg L- for chromium (III) and (VI) respectively. The present method was also applied for the simultaneous determination of chromium in the presence of some foreign ions with satisfactory analytical responses.
Application of the extended real associated solution theory to excess molar enthalpies and excess molar volumes of binary mixtures of (benzene or 1-alkanol + quinoline)
(Elsevier, 2005-06-01) Deenadayalu, Nirmala; Letcher, Trevor M.
Excess molar enthalpies and excess molar volumes of binary mixtures of (benzene or methanol or ethanol or 1-propanol or 1- butanol+quinoline) as a function of composition at a pressure of 1 atm and a temperature of 298.15 K have been used to test the Extended Real Solution Theory, ERAS, of nonelectrolyte solutions. The ERAS theory accounts for free volume effects according to the Flory–Patterson theory and for association effects: self and crossassociation between the molecules involved. The ERAS theory results for the binary mixtures (benzene or an alkanol+quinoline) indicates strong hydrogen bonding effects between unlike molecules given by the predicted hydrogen bonding energy between two dissimilar compounds. Comparison is also made between the chemical and physical contribution to the ERAS theory. The Extended Real Associated Solution theory describes the published Vm E data better than the published Hm E data.
Excess molar volumes and partial molar volumes for (propionitrile + an alkanol) at T = 298.15 K and p = 0.1 MPa
(Elsevier, 2006) Deenadayalu, Nirmala; Bhujrajh, P.
The excess molar volumes and the partial molar volumes for (propionitrile + an alkanol) at T = 298.15 K and at atmospheric pressure are reported. The hydrogen bonding between the OH NC groups are discussed in terms of the chain length of the alkanol. The alkanols studied are (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-pentanol). The excess molar volume data was fitted to the Redlich–Kister equation The partial molar volumes were calculated from the Redlich–Kister coefficients.
Ternary excess molar volumes of {methyltrioctylammonium bis(trifluoromethylsulfonyl)imide + ethanol + methyl acetate, or ethyl acetate} systems at T = (298.15, 303.15, and 313.15) K
(Elsevier, 2010-01-28) Gwala, Nobuhle V.; Deenadayalu, Nirmala; Tumba, Kaniki; Ramjugernath, Deresh
The activity coefficient at infinite dilution for 30 solutes: alkanes, alkenes, cycloalkanes, alkynes, ketones, alcohols, and aromatic compounds was determined from gas–liquid chromatography (glc) measurements at three temperatures (303.15, 313.15, and 323.15) K. The ionic liquid: trioctylmethylammonium bis(trifluoromethylsulfonyl)imide, was used as the stationary phase. For each temperature, values were determined using two columns with different mass percent packing of the ionic liquid. The selectivity value was calculated from the to determine the suitability of the solvent as a potential entrainer for extractive distillation in the separation of an hexane/benzene mixture, indicative of a typical industrial separation problem for benchmarking purposes.
Ochratoxins--food contaminants : impact on human health
(MDPI, 2010-04-20) Reddy, Lalini; Bhoola, Kanti
Ochratoxins are secondary metabolites of Aspergillus and Penicillium, that are hazardous to health through contamination of dietary foods. Ochratoxin A (OTA) remains the single most potent member of this group of mycotoxins. OTA has a long half-life in humans and is thus easily detected in serum. Dietary intake studies have confirmed link between endemic nephrotoxicity in humans to their daily household intake of OTA. OTA has been reported to contribute to endemic nephrotoxicity and carcinogenicity in humans and animals. OTA produces renal tumours, DNA adducts and chromosomal aberrations in kidneys. OTA may be embryotoxic, teratogenic, and immunotoxic only at doses higher than those causing nephrotoxicity. The incidence of endemic nephrotoxicity has been mostly reported in northeast Europe since the early fifties. Recent studies however have warned that OTA and other toxins, such as aristolochic acid, show very similar renal pathology. There is thus the need for thorough co-occurrence studies on toxin incidence.
Bioaugmentation efficiency of diesel degradation by Bacillus pumilus JLB and Acinetobacter calcoaceticus LT1 in contaminated soils
(2010-10-11) Pillay, Charlene; Lin, Johnson
The abilities of diesel-degrading Bacillus pumilus JLB and Acinetobacter calcoaceticus LT1 were tested in contaminated soils. The effect of nutrient supplementation on bioaugmented samples was also examined. The results show that bio-augmentation and biostimulation accelerated significantly (p < 0.05) the diesel degradation in the contaminated loam soil and sea sand. Supplementing fertilizers to the augmented loam samples did not result in a significantly higher degradation rate. Furthermore, A. calcoaceticus LT1 alone failed to stimulate higher degradation rates in sea sand unless further supplementation of fertilizer. The results from environmental scanning electron microscopy demonstrate the population increases, then decreases in augmented samples corresponding to the level of diesel degradation. Fungi-like microorganisms became dominant in contaminated loam soil at the end of the study but not in sea sand. The study shows that it is critical not only to understand the physiology of the inoculum but also how it affects microbial community structure and function before the microorganism being introduced in the contaminated soil.
Preparation, spectrochemical, and computational analysis of L-Carnosine (2-[(3-Aminopropanoyl)amino]-3-(1H-imidazol-5- yl)propanoic Acid) and Its Ruthenium (II) coordination complexes in aqueous solution
(MDPI, 2011-12-09) Branham, Michael Lee; Bisetty, Krishna; Sabela, Myalowenkosi Innocent; Govender, Thirumala; Singh, Parvesh
This study reports the synthesis and characterization of novel ruthenium (II) complexes with the polydentate dipeptide, L-carnosine (2-[(3-aminopropanoyl)amino]-3-(1H-imidazol-5-yl)propanoic acid). Mixed-ligand complexes with the general composition [MLp(Cl)q(H2O)r]·xH2O (M = Ru(II); L = L-carnosine; p = 3 − q; r = 0–1; and x = 1–3) were prepared by refluxing aqueous solutions of the ligand with equimolar amounts of ruthenium chloride (black-alpha form) at 60 °C for 36 h. Physical properties of the complexes were characterized by elemental analysis, DSC/TGA, and cyclic voltammetry. The molecular structures of the complexes were elucidated using UV-Vis, ATR-IR, and heteronuclear NMR spectroscopy, then confirmed by density function theory (DFT) calculations at the B3LYP/LANL2DZ level. Two-dimensional NMR experiments (1H COSY, 13C gHMBC, and 15N gHMBC) were also conducted for the assignment of chemical shifts and calculation of relative coordination-induced shifts (RCIS) by the complex formed. According to our results, the most probable coordination geometries of ruthenium in these compounds involve nitrogen (N1) from the imidazole ring and an oxygen atom from the carboxylic acid group of the ligand as donor atoms. Additional thermogravimetric and electrochemical data suggest that while the tetrahedral-monomer or octahedral-dimer are both possible structures of the formed complexes, the metal in either structure occurs in the (2+) oxidation state. Resulting RCIS values indicate that the amide-carbonyl, and the amino-terminus of the dipeptide are not involved in chelation and these observations correlate well with theoretical shift predictions by DFT.
Apoptosis in the human laryngeal carcinoma (HEp-2) cell line by Bulbine natalensis and B. Frutescens fractions
(IJBPR, 2012) Singh, Rishan; Reddy, Lalini
Many plants that belong to the genus Bulbine have compounds in their roots and leaves which are considered important for traditional treatments. The stems and roots of Bulbine species are believed to contain anticancer compounds such as anthraquinones, including chrysophanol and knipholone. However, in general, people utilise plants of the Bulbine genus for the treatment of rashes, itches, wounds, burns, cracked lips and cracked skin. This study assessed the effect of aqueous and organic fractions of Bulbine natalensis and Bulbine frutescens on the human laryngeal carcinoma cell line (HEp-2) for apoptosis. The MTT assay was used to determine the cytotoxicity of the fractions administered and to select fractions for analysis of bax and caspase-3 gene expression, which are induced during programmed cell death type 1, known as apoptosis. All of the B. natalensis fractions induced expression of caspase-3, while the tested B. frutescens aqueous root fractions failed to induce expression of caspase-3. The variation in bax gene expression indicated that HEp-2 cell death was due to apoptosis and other unknown forms of cell death that may or may not activate caspase-3 gene expression.
Molecular immunogenetics of apoptosis : experimental dilemas
(International Journal of Biological & Pharmaceutical Research, 2012) Singh, Rishan; Reddy, Lalini
There have been several research articles published on the biological and biochemical nature of apoptosis. These have included studies on the molecular genetics of apoptosis. Apart from the genes that are involved in the apoptotic cascade, there are several other genes that are either activated or inhibited when cell lines are exposed to apoptotic stimuli. This article addresses the simplicity and complexity of the genetic nature of apoptosis in a variety of cell lines.
Comment on invalid JWKB unstable solutions of combined inertial-Rossby waves
(Annales Geophysicae, 2012) McKenzie, J. F.
Methyl 2,6-diphenyl-1-p-tolyl-4-(p-tolyl- amino)-1,2,5,6-tetrahydropyridine-3- carboxylate
(Acta Cryst., 2012) Venugopala, Katharigatta Narayanaswamy; Nayak, Susanta K.; Odhav, Bharti
In the title compound, C33H32N2O2, the tetrahydropyridine ring adopts a boat conformation with the carbonyl group in an s-cis conformation with respect to the C=C bond of the six-membered tetrahydropyridine ring. The molecular conformation is stabilized by intramolecular N-H...O, C-H...O and C-H...[pi] interactions. Formation of centrosymmetric head-to-head dimers is observed through pairwise intermolecular N-H...O hydrogen bonds. Additional weak C-H...O and C-H...[pi] interactions stabilize the three-dimensional molecular assembly.
Evaluation of enantioresolution of (±)-catechin using electrokinetic chromatography and molecular docking
(SRP, 2012) Sabela, Myalowenkosi Innocent; Singh, Parvesh; Gumede, Njabulo Joyfull; Bisetty, Krishna; Sagrado, Sagrado
This study involves the enantioresolution of (±) catechin with the highly sulphated beta cyclodextrin (HS-β-CD) as a chiral selector using capillary electrophoresis (CE). The purpose of this study was to be tter understand enantioresolution amongst host-guest interactions. Furthermore, molecular docking was carried out to elucidate the mechanism of the enantioselective separations of (±) catechin enantiomers obtained in Electrokinetic chroma tography (EKC). A large difference in the interaction energies observed between the two enantiomers represents significant enantiodifferentiation. Our results also suggest that the host-guest interactions between the phenyl ring of the ligand and the open cavity of the HS-β-CD are due mainly to hydrophobic interactions. Interestingly, the stronger interactions observed with (+)-catechin is consistent with the elution order observed in the CE experiments.
A rapid method for determining chlorobenzenes in dam water systems
(Africa Journals Online, 2012-01-01) Moodley, Kandasamy G.; Chetty, Deenadayalan Kisten; Ramphal, Sayjil Rohith; Gericke, G.
A method using direct immersion solid phase microextraction (DI-SPME) coupled to gas chromatography equipped with a flame ionisation detector (GC-FID) was developed for the analysis of 7 chlorinated benzenes in dam water. The main parameters affecting the DI-SPME process were optimised. The optimised method comprises the use of a 100 µm polydi-methylsiloxane (PDMS) fibre coating; 5 mℓ sample size; 700 r/min rate of agitation and an extraction time of 30 min. The calibration curve was linear with correlation coefficients ranging from 0.9957–0.9995 for a concentration range of 1–100 ng/mℓ. The limits of detection and quantification ranged from 0.020–0.265 ng/mℓ and 0.204–2.65 ng/mℓ, respectively. Recoveries ranged from 83.6–107.2% with relative standard deviation of less than 9.2%, indicating that the method has good precision. The method is reliable and is free of matrix interferences. Water samples collected from Grootdraai Dam were analysed using the optimised conditions to assess the potential of the method for trace level screening and quantification of chlorobenzenes. The method proved to be efficient, as 1,3 dichlorobenzene, 1,4-dichlorobenzene and pentachlorobenzene were detected at concentrations of 0.429 ng/mℓ, 1.685 ng/mℓ and 1.433 ng/mℓ, respectively.
Groundwater : characteristics, qualities, pollutions and treatments : an overview
(International Journal of Water Resources and Environmental Engineering, 2012-02-22) Otieno, Fredrick Alfred O.; Olumuyiwa, I. Ojo; Ochieng, George M.
This review considered groundwater resources, its characteristics, qualities, pollutions and available treatments. Groundwater refers to all the water occupying the voids, pores and fissures within geological formations, which originated from atmospheric precipitation either directly by rainfall infiltration or indirectly from rivers, lakes or canals. The chemical, physical and bacterial characteristics of groundwater determine its usefulness for various purposes. The ground water analysis reviewed includes pH, chlorine content, total dissolved solids (TDS), turbidity, dissolved oxygen and hardness others include alkalinity, chloride, toxic chemicals and the presence of coli form organisms. The treatments considered are; aeration, coagulation, flocculation, sedimentation and filtration. Appropriate technology methods such as container storage, pot chlorination, boiling and solar disinfection were discovered to be in use. The paper concluded by recommending research into quantifying groundwater, its quality and treatment based on the above overview.
Improvement of ethanol production from sugarcane molasses through enhanced nutrient supplementation using Saccharomyces cerevisiae
(Academic Journals, 2012-03) Nofemele, Zuko; Shukla, Pratyoosh; Trussler, Arthur; Permaul, Kugen; Singh, Suren
Saccharomyces cerevisiae as a yeast cream was utilized for alcoholic fermentation using sugar cane molasses. In the present study, fermentation was optimized for urea and yeast hydrolysate (YH) dosage and the combined effect was evaluated. Total sugars as inverts (TSAI) composition of molasses were -1 determined by HPLC as 39% (m/v). Urea concentrations of 4, 2 and 3 gl showed optimal ethanol -1 production at 30, 35 and 40°C respectively. A YH concentration of 0.5 gl resulted in an ethanol yield of 8.7% (m/v) with a fermentation efficiency of 85.12%. Under optimized conditions (35°C) significant improvements were noticed with ethanol yield of 7.8% (m/v) and efficiency of 76.3%.
Fine tuning the transcription of ldhA for D-lactate production
(Springer-Verlag, 2012-03-20) Singh, Suren
Nonlinear ion cyclotron and ion-acoustic waves have been studied in an electron–positron–ion plasma. Using Boltzmann distributions for the electrons and positrons and fluid equations for the ions, a set of nonlinear equations in the rest frame of the propagating wave is derived and numerically solved for the electric field. A scan of parameter space reveals a range of solutions for the parallel electric field, from sinusoidal to sawtooth to highly spiky waveforms. The results are compared with satellite observations.
Nonlinear low-frequency structures in an electron–positron–ion plasma
(Cambridge University Press, 2012-03-20) Moola, S.; Lazarus, Ian Joseph; Bharuthram, R.
Nonlinear ion cyclotron and ion-acoustic waves have been studied in an electron–positron–ion plasma. Using Boltzmann distributions for the electrons and positrons and fluid equations for the ions, a set of nonlinear equations in the rest frame of the propagating wave is derived and numerically solved for the electric field. A scan of parameter space reveals a range of solutions for the parallel electric field, from sinusoidal to sawtooth to highly spiky waveforms. The results are compared with satellite observations.
Shearing radiative collapse with expansion and acceleration
(American Institute of Physics, 2012-03-28) Rajah, Surversperi Suryakumari; Thirukkanesh, S.; Maharaj, S. D.
We investigate the behaviour of a relativistic spherically symmetric radiative star with an accelerating, expanding and shearing interior matter distribution in the presence of anisotropic pressures. The junction condition can be written in standard form in three cases: linear, Bernoulli, and Riccati equations. We can integrate the boundary condition in each case and three classes of new solutions are generated. For particular choices of the metric we investigate the physical properties and consider the limiting behaviour for large values of time. The causal temperature can also be found explicitly.
Chemical composition of essential oil of Psidium cattleianum var. lucidum (Myrtaceae)
(Academic Journals, 2012-04-12) Chalannavar, Raju K.; Baijnath, Himansu; Odhav, Bharti; Venugopala, Katharigatta Narayanaswamy
The aim of this study was to investigate the essential oil composition of Psidium cattleianum var. lucidum from South Africa. The essential oils were extracted by hydrodistillation and the components were identified by gas chromatography coupled to mass spectrometry (GC-MS) to determine the chemical composition of the essential oil. A total of 53 chemical components were identified, accounting for 61% of the essential oil. The major component was caryophyllene oxide (12.43%), while other predominant constituents were identified as bicyclo(4.4.0)dec-l-ene (6.61%), 2,3-butanediol diacetate (4.84%) and patchoulene (4.73%). The presence of many terpenic and ester compounds is thought to contribute to the unique flavor of the P. cattleianum var. lucidum leaves.
Cycloaddition reactions of Azatrienes with Sulfene
(Scientific Research, 2012-04-23) Bisetty, Krishna; Singh, Parvesh
Unprecedented cycloaddition reactions of azatrienes (1) with sulfene leading to the synthesis of functionalized thiazine-dioxide derivatives (5) are described. The reactions were found be highly regioselective resulting in the formation of only [4 + 2] cycloadducts.