Chemistry Department

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Activation Energy of Thermal Decomposition of LaC2O4Br
(Kluwer Academic Publishers, 1991) Lugwisha, Esther H. J.; Mulokozi, A. M.; Masabo, M. K. J.
The activation energy of the thermal decomposition of finely ground LaC2O4Br was determined according to the method of Ozawa asE a=203.83 kJ mol–1. As compared to the value for the parent oxalate La2(C2O4)3 E a=130 kJ/mol), this value is higher by about 70 kJ/mol, which is consistent with the increased interaction between the metal and oxalate ions. The substitution of Br by Cl does not affect the decomposition kinetics profoundly.Gem der Methode von Ozawa wurde die Aktivierungsenergie der thermischen Zersetzung von fein zermahlenem LaC2O4Br mitE a=208.83 kJ/mol bestimmt. Beim Vergleich mit dem entsprechenden Wert fr die Mutterverbindung La2(C2O4)3 (E a=130 kJ/mol) erweist sich dieser Wert um etwa 70 kJ/mol hher, was mit der verstrkten Wechselwirkung zwischen Metall- und Oxalationen bereinstimmt. Der Ersatz von Br durch Cl hat keinen tiefgreifenden Einflu auf die Kinetik der Zersetzung
The Activity of Invertase Immobilized on Cashew Nut Shell Liquid-Templated Large Pore Silica Hybrids
(2011) Mubofu, Egid B.; Mdoe, James; Kinunda, Grace
The characterization and activity of invertase enzymes immobilized on large pore micelle templated silica (LP-MTS) hybrid materials is reported. The LP-MTS hybrid materials were prepared by a co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyltrimethoxysilane (AMPTS) in a cashew nut shell liquid (CNSL) template. A commercially available dodecylamine template was also used to afford similar materials, hereinafter abbreviated as DDA-MTS, for comparison purposes. The prepared materials were characterized by different techniques to determine their physicochemical properties. The maximum loading for the amine groups in LP-MTS and DDA-MTS were 3.3 and 2.8 mmol g�1, respectively. Modification of the materials for immobilization of the invertase enzyme was done by reacting them with glutaraldehyde resulting in Glu-LP-MTS or Glu-DDA-MTS. The as-prepared hybrid materials have surface areas ranging from 100 to 214 m2 g�1 with pore diameters ranging from 3.1 to 25 nm. Scanning electron microscopy (SEM) images show that LP-MTS and DDA-MTS materials comprise of roughly spherical particles whereas enzyme and glutaraldehyde supported micelle templated silicas show a rupture of the spherical particles to a fine powder. The activities of free and immobilized invertases have been determined by measuring the amount of reducing sugar produced upon hydrolysis of sucrose at different temperatures, pH and substrate concentrations. Both free and immobilized invertase enzymes showed a maximum activity at a particular optimum temperature, pH and substrate concentration. The maximum activity for the free invertase was 15 229 U at pH 5.0 and at 40 1C whereas those of the LP-MTS immobilized invertases were 14 833 U and 14 625 U for covalent and cross-linked invertases, respectively, at pH 4.0 and 40 1C. The maximum activity for DDA-MTS covalently immobilized invertase was 4750 U, at pH 4.0 and 40 1C.
The Activity of Invertase Immobilized on Cashew Nut Shell Liquid-Templated Large Pore Silica Hybrids,
(Royal Society of Chemistry, 2011) Mubofu, Egid, B; Mdoe, James, E; Kinunda, Grace
The characterization and activity of invertase enzymes immobilized on large pore micelle templated silica (LP-MTS) hybrid materials is reported. The LP-MTS hybrid materials were prepared by a co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyltrimethoxysilane (AMPTS) in a cashew nut shell liquid (CNSL) template. A commercially available dodecylamine template was also used to afford similar materials, hereinafter abbreviated as DDA-MTS, for comparison purposes. The prepared materials were characterized by different techniques to determine their physicochemical properties. The maximum loading for the amine groups in LP-MTS and DDA-MTS were 3.3 and 2.8 mmol g−1, respectively. Modification of the materials for immobilization of the invertase enzyme was done by reacting them with glutaraldehyde resulting in Glu-LP-MTS or Glu-DDA-MTS. The as-prepared hybrid materials have surface areas ranging from 100 to 214 m2 g−1 with pore diameters ranging from 3.1 to 25 nm. Scanning electron microscopy (SEM) images show that LP-MTS and DDA-MTS materials comprise of roughly spherical particles whereas enzyme and glutaraldehyde supported micelle templated silicas show a rupture of the spherical particles to a fine powder. The activities of free and immobilized invertases have been determined by measuring the amount of reducing sugar produced upon hydrolysis of sucrose at different temperatures, pH and substrate concentrations. Both free and immobilized invertase enzymes showed a maximum activity at a particular optimum temperature, pH and substrate concentration. The maximum activity for the free invertase was 15 229 U at pH 5.0 and at 40 °C whereas those of the LP-MTS immobilized invertases were 14 833 U and 14 625 U for covalent and cross-linked invertases, respectively, at pH 4.0 and 40 °C. The maximum activity for DDA-MTS covalently immobilized invertase was 4750 U, at pH 4.0 and 40 °C
Aflatoxin Levels in Sunflower Seeds and Unrefined Sunflower Oils from Singida, Tanzania
(Taylor & Francis, 2018-03-16) Mohammed, Salum; Munissi, Joan J.E; Nyandoro, Stephen S.
A total of 61 samples comprising sunflower seeds (40) and unrefined sunflower oils (21) samples collected randomly from Singida, Tanzania were analysed by Reverse Phase-high performance liquid chromatography (RP-HPLC). 15% (6/40) of the seed samples were contaminated with aflatoxin B1 ranging from limit of detection (LOD) to 218 ng g−1 with three of them exceeding the European Commission/European Union (EC/EU) and Tanzania Bureau of Standards (TBS)/Tanzania Food and Drug Authority (TFDA) maximum limits of 2 ng g−1 for AFB1 in oilseeds. The levels of total aflatoxins (AFT) in seeds ranged from LOD to 243 ng g−1. Other aflatoxins, except AFG2, were also detected. For the unrefined sunflower oils, the levels of AFB1 ranged from LOD to 2.56 ng mL−1. About 80.9% (17/21) of the analysed oil samples contained AFB1 of which 17.65% (3/17) exceeded the EC/EU and TBS/TFDA maximum limits of 2 ng mL−1. Other aflatoxins were also detected in the oils. The measured levels indicate there is a need for food quality education among food processors.
Aflatoxin M1 in raw milk and aflatoxin B1 in feed from household cows in Singida, Tanzania
(Taylor & Francis, 2016-02) Mohammed, Salum; Munissi, Joan J. E.; Nyandoro, Stephen S.
Aflatoxin M1 (AFM1) contamination in raw milk from household cows fed with sunflower seedcakes or sunflower-based seedcake feeds was determined in 37 milk samples collected randomly from different locations in Singida region, Tanzania. Aflatoxin B1 (AFB1) contamination in sunflower-based seedcake feed was determined in 20 feed samples collected from the same household dairy farmers. The samples were analysed by RP-HPLC using fluorescent detection after immunoaffinity column clean-up. Recoveries were 88.0% and 94.5%, while the limits of detection (LOD) were 0.026 ng mL(-1) and 0.364 ng g(-1) for AFM1 and AFB1, respectively. Of the analysed cow's milk samples, 83.8% (31/37) contained AFM1, with levels ranging from LOD to 2.007 ng mL(-1), exceeding both the European Commission (EC) and Tanzania Food and Drug Authority (TFDA) limit of 0.05 ng mL(-1). Of the contaminated samples, 16.1% exceeded the Codex Alimentarius limit of 0.5 ng mL(-1). AFB1 was present in 65% (13/20) of the feed samples with levels ranging from LOD to 20.47 ng g(-1), 61.53% exceeding the TFDA and EC maximum limits of 5 ng g(-1) for complete dairy animal feed. The observed AFM1 and AFB1 contamination necessitates the need to raise awareness to dairy farmers in Tanzania to safeguard the health of the end-users.
Alkyl Group-Tagged Ruthenium Indenylidene Complexes: Synthesis, Characterization and Metathesis Activity
(Elsevier, 2015) Yu, Baoyi; Hamad, Fatma B.; Leus, Karen; Lyapkov, Alex A.; Van Hecke, Kristof; Verpoort, Francis
We report on the synthesis of ruthenium indenylidene catalysts [RuCl2(3-R-1-indenylidene)(PCy3)2inwhich R is iso-propyl (7a), tert-butyl (7b) or cyclohexyl (7c)]. The obtained alkyl tagged indenylidenecatalysts were analyzed by means of IR, elementa l analysis, NMR and single crystal X-Ray diffractionanalysis. Furthermore, the catalytic performance of these new complexes was examined in dif ferentmetathesis reactions: ring-closing metathesis (RCM), ring-closing ene-yne metathesis (RCEYM), ring-opening metathesis polymerization (ROMP) and cross metathesis (CM), exhibiting a comparable activ-ity in comparison with the commercially available catalyst 3a
Antifungal Enantiomeric Styrylpyrones from Sanrafaelia ruffonammari and Ophrypetalum odoratum
(Springer Link, 2014) Malebo, Hamisi M.; Kihampa, Charles; Mgina, Clarence A.; Sung’hwa, Fortunatus; Waibel, Reiner; Jonker, Stephan A.; Nkunya, Mayunga H. H.
Phytochemical investigation of Sanrafaelia ruffonammari Verd and Ophrypetalum odoratum Diels that belongs to the rare genera confined to East African coastal forests led to the isolation of enantiomeric styrylpyrone dimer, (±)-5-methoxy-7-phenyl-[4-methoxy-2-pyronyl]-1-(E)-styryl-2-oxabicyclo-[4.2.0]-octa-4-en-3-one (1) alongside (+)-6-styryl-7,8-epoxy-4-methoxypyran-2-one (2) and the enantiomeric (+)- (3) and (-)-6-styryl-7,8-dihydroxy-4-methoxypyran-2-ones (4). Their structures were established by means of spectroscopic methods. In this paper we reveal for the first time the occurrence of styrylpyrones in East African biodiversity. (+)-6-Styryl-7,8-epoxy-4-methoxypyran-2-one (2) and the dihydroxystyrylpyrone enantiomer (3) showed in vitro antifungal activity against Candida albicans at a concentration of 24.4 and 26.2 µM with zones of inhibition of 17 and 9 mm, respectively. Compound 2 exhibited strong activity in the brine shrimp test with LC50 = 1.7 µg/mL. Their high cytotoxic and antifungal activities render them candidates for further scientific attention for drug development programs against cancer and microbial infections.
Antimalarial Activity of Tanzanian Plants and Their Active Constituents: The Genus Uvaria 1
(1991-08) Nkunya, Mayunga H.H.; Weenen, Hugo; Bray, Dorothy; Mgani, Quintino A.; Mwasumbi, L. B.
Antimycobacterial and Cytotoxic Activities of Extracts from Fungal Isolates of Lake Magadi
(International Formulae Group, 2017) Kowanga, Keno D; Munissi, Joan J.E; Masalu, Rose; Nyandoro, Stephen S.; Masimba, Pax; Gatebe, E.
Antimycobacterial and cytotoxic activities of extracts from fungal isolates of Lake Magadi Keno David Kowanga, Joan John Eliona Munissi, Rose Masalu, Stephen Samwel Nyandoro, Pax Masimba, Erastus Gatebe Abstract In this study, antimycobacterial and cytotoxic activities of ethyl acetate extracts of fungal isolates from Lake Magadi were evaluated. The extracts were tested against Mycobacterium madagascariense (MM) and M. indicus pranii (MIP), and cytotoxicity against brine shrimp (Artemia salina) larvae. Fungal strains were identified using sequence comparison of the Internal Transcribed Spacer (ITS) region. Potent antimycobacterial activities against MM were exhibited by extracts from Volutella colletotrichoides, Helicoon richonis, Penicillium limosum, P. sacculum, Aspergillus parasiticus and A. nomius strains that exhibited minimum inhibition concentration (MIC) in the range of 0.19 – 12.5 mg/mL. On the other hand, significant antimycobacterial effects against MIP was shown by extracts from V. colletotrichoides, H. richonis, A. parasiticus, Fusarium merismoides, A. silvaticus and A. fumigatus strains in the same MIC range. Notable cytotoxic activities of the extracts were from A. versicolor, A. nomius, P. janthinellum and H. richonis strains with LC50 values ranging from 46.60 – 98.12 μg/mL. These results indicate that fungi inhabiting Lake Magadi have the ability to produce bioactive metabolites that could be further explored for potential medicinal agents
Antimycobacterial and cytotoxicity evaluation of the constituents of Monodora carolinae
(2013) Magoria, Nyangi; Nyandoro, Stephen S.; Munissi, Joan J. E.; Heydenreichb, Matthias
Phytochemical investigation of the stem bark of the recently described species Monodora carolinae (Annonaceae) afforded prenylindole derivatives (E)-4-(1H-indol-6-yl)-but-3-en-2-one (1), 5-formylindole (2), fatty acid (Z)-hexade-7-enoic acid (3) and the lignanamide cannabisin B (4). The structures of the isolated compounds were established using NMR and MS analyses. The antimycobacterial activities of the extracts and isolated compounds were evaluated against Mycobacterium madagascariense (MM) and M. indicus pranii (MIP) using the two-fold microtitre dilution method. While the extracts exhibited minimum inhibitory concentration (MIC) ranging from 500 – 1000 ìg/mL, the isolated compounds were 125 – 250 ìg/mL, indicating very low activity. Cytotoxic effects were evaluated using brine shrimp larvae whereby the ethanolic extract of the root bark exhibited the lowest LC50 (< 3ìg/mL). Isolation of prenylindole derivatives is of chemotaxonomic significance that affirms taxonomic placement of this plant species into the genus Monodora. This is the first time cannabisin B is reported from the genus Monodora.
Aromatic Bio-Based Solvents
(John Wiley & Sons, 2017-06-30) Mubofu, Egid B.; Mgaya, James; Munissi, Joan J.E
This chapter focuses on alkylresorcinols (AR) and cashew nut shell liquid (CNSL) as bio‐based solvents from agricultural produce and waste. It highlights the possible biological sources for bio‐based aromatics, such as cereals and CNS wastes, and the techniques for their extraction. The chapter also introduces the possible potential applications of these extracts as solvents or reagents in the production of functional or platform chemicals. The competitive advantage of utilizing agricultural by‐products or wastes, such as cereal bran and CNSs, as renewable bio‐resources for the production of aromatic bio‐based solvents is manifested in non‐interference with food supply and their contributions towards waste minimization. Thus, this chapter centres its discussion onaromatic bio‐based solvents from agricultural by‐products and waste materials, and emphases on resorcinolic lipids and CNSL. Basically, there are three methods used to extract CNSL from the shells: solvent extraction, thermal extraction and mechanical extraction
Arsenic: A Toxic Trace Element of Public Health Concern in Urban Roadside Soils in Dar Es Salaam City
(JMES, 2014) Luilo, G. B.; Othman, Othman C.; Mrutu, A.
Motor vehicles have been associated with high levels of trace metals in urban soils and the metals are mostly emitted though exhaust emissions, brake pad and tire abrasions. This study reports the levels of arsenic in roadside soils obtained from the surface at a depth of 0-5 cm in the Dares Salaam city which has the highest average daily traffic density in the country. The soils samples were collected at 1 m, 5 m, 15 m, 35 m, 50 m and 150 m distances from the road edge at each sampling site. Results showed that roadside soils were contaminated with arsenic and its levels ranged from 0.03 - 0.65 ppm (mean = 0.23 ppm). The amount of arsenic in the soil at each site decreased exponentially with increasing distance up to 35 m distance from the road edge. The Analysis of Variance (ANOVA) test showed that average arsenic levels in the soils varied significantly with study sites (F = 4.14, p = 0.01, n = 5) while the linear regression between average arsenic in all soil samples and average daily traffic density was statistically insignificant (r2 = 0.47, p = 0.21, n = 5). However, the observed spatial distribution of arsenic with increasing distance from the road edge strongly suggests that arsenic levels above background level in the study sites owe its source from traffic emissions.
Assessment of Pesticide Residues in Tomatoes and Watermelons (Fruits) from Markets in Dar es Salaam, Tanzania
(University of Port Harcourt, 2017) Mahugija, John A.M.; Khamis, Farhat A.; Lugwisha, Esther H.J.
This study investigated the levels of pesticide residues in selected fruits from major markets in Dar es Salaam city. Samples of tomatoes and watermelons were analysed for eighteen organochlorine, organophosphorus and pyrethroid pesticide residues. Extraction was performed using acetone followed by dichloromethane: cyclohexane mixture and the extracts were cleaned-up using florisil. The compounds were determined by gas chromatography–mass spectrometry (GC–MS). Pesticides and metabolites were detected in 95.8% of the samples. The compounds detected included chlorpyrifos, α-endosulfan, β-endosulfan and cypermethrin and their highest concentrations were 3810 ± 50, 370 ± 20, 120 ± 6 and 50 ± 4 ng/g, respectively. Others were p,p'-DDD, o,p'-DDD, p,p'-DDE and α-HCH with highest concentrations varying from 1 ± 0.5 to 20 ± 1.2 ng/g. There were no significant variations in concentrations of the pesticide residues between the fruits and among the sampling sites, indicating similarities in contamination patterns. The concentrations of the contaminants were above the maximum residue limits (MRLs) in 41.7% to 50% of the tomatoes and watermelons indicating risks and concerns for public health. The Tanzanian agrochemicals and food regulatory agencies (e.g. TPRI, TFDA and TBS) and the government in general should ensure strict applications of laws that regulate pesticides in the country and develop effective educational programmes for farmers to apply good agricultural practices such as reducing the use of pesticides, applying appropriate pesticides and doses, and restrict the spray before harvesting. The consumers should thoroughly wash or process the fruits to reduce the levels.
A Bellows-Shape Electrostatic Microactuator
(1999-02) Williford, Clint W.; Li, Z.; Wang, Z.; Bricka, Mark R.; Bahemuka, T. E.; Mubofu, Egid B.; Minami, Kazuyuki; Morishita, H.; Esashi, Masayoshi
Bidentate Schiff Base Ruthenium Complexes as Precursors of Homogeneous and Immobilized Catalysts
(Bentham Science, 2013) Verpoort, Francis; Yu, Baoyi; Hamad, Fatma B.; Velazquez, Heriberto D.; Luo, Zhixiong
The paper presents an overview of the work conducted in our group on the synthesis of a novel class of homogeneous and immobilized Ru-complexes containing Schiff bases as O, N-bidentate ligands benefiting from a versatile, quite general and thoroughly exemplified two-step procedure. The new Ru-complexes with improved stability incorporate a variety of Schiff bases, associated with traditional inorganic and organic ligands such as chloride, phosphanes, arenes, cyclodienes, NHC etc., and different carbenes (alkylidene, vinylidene, allenylidene and indenylidene). By a proper choice of the Schiff base, useful physical and chemical properties of the derived Ru-complexes could be induced resulting in tunable catalytic activity for metathesis and related processes. A pertinent example is the latency of selected Schiff base Ru catalysts which by becoming active only under specific conditions (heat or acid activation) are ideal for industrial applications, e.g. reaction injection molding processes. The synthetic approaches that are critically discussed in this chapter have led to a diversity of Ru-complexes of which several members have risen to the rank of commercial catalysts.
Bio-recognition Ability of Polysaccharides as Piezo Quartz Biosensors
(2012) Kalmykova, E. N.; Mgina, Clarence A.
Piezoquartz biosensors (PQB) which are analytical devices for recognition of biochemical interactions have recently attracted increasing interest from different researchers such as analysts, immune-chemists, medical doctors, environmentalists, etc. This is due to the advantages of PQB for having high detection sensitivity (at ng and mg level depending on the mass of sorbates or micro-organisms) and the ability to monitor biochemical reactions in turbid or highly coloured liquids (including in biological fluids) in real time. The use of additional markers and preliminary sample preparation are not required in this biorecognition process. This paper reports on the principle of the PQB and the design units to perform analysis in static and dynamic conditions using different types of biomolecules (immunoglobulins, DNA, lipopolysaccharides, glycoconjugates, hapten-protein conjugates and polysaccharides). Research results performed at the Department of Chemistry, Lipetsk State Technical University (Russia) and School of Physics, College of Natural Sciences, UDOM (Tanzania) are presented. The report aims to review various examples of use of carbohydrate molecules and glycoconjugates in the design of the PQB. These examples include the following: use of sulphated polysaccharides to increase the strength of the sensor’s bio-laye;, use of glycolipids such as O-antigens of bacteria (Yersinia enterocolitica) with different chemical structures in the development of immunosensors for the determination of specific immunoglobulins at 3-100 mg/ml levels in serum; and the use of polysaccharide hydrogels of the first chemical structure (hyaluronic acid, zosteran and neutral and acidic polysaccharide fractions isolated from water hyacinth Eichhornia crassipes) in studying their effectiveness in Pb2 + ions sorption.
Bioactivities of extracts, debromolaurenterol and fucosterol from macroalgae species
(Dar es Salaam University Press, 2018-06) Begum, Sartaz; Nyandoro, Stephen S.; Buriyo, Amelia S.; Makangara, John J; Munissi, Joan J.E; Duffy, Sandra; Avery, Vicky M.; Erdelyi, Mate
Parasitic diseases including malaria, and other numerous microbial infections and physiological diseases are threatening the global population. Tanzanian coast shores are endowed with a variety of macroalgae (seaweeds), hitherto unsystematically explored to establish their biomedical potentials. Thus, antiplasmodial activity using malarial imaging assay, antimicrobial activity using microplate dilution technique, antioxidant activity using DPPH radical scavenging method and cytotoxicity using brine shrimp test were carried out on crude extracts from the selected species of algae (Acanthophora spicifera, Cystoseira myrica, Cystoseira trinodis, Laurencia filiformis, Padina boryana, Sargassum oligocystum, Turbinaria crateriformis, Ulva fasciata and Ulva reticulata) occurring along the coast of Tanzania. The extracts showed antimicrobial activities with MIC ranging from 0.3- 5.0 μg/mL against Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans; DPPH radical scavenging activity at EC50 1.0- 100 μg/mL and cytotoxicity on brine shrimp larvae with LC50 value ranging from20 - 1000 μg/mL. The extracts from C. myrica and P. boryana inhibited growth of Plasmodium falciparum (3D7 strain) by 80 and 71%, respectively at 40 μg/mL while a sesquiterpene debromolaurinterol (1) which was chromatographically isolated from C. myrica exhibited antiplasmodial activity with IC50 20 μM whereas a sterol fucosterol (2) from P. boryana showed weak activity at 40 μM. Bioactivities portrayed by the investigated extracts indicate their ingredients as potential sources of bioactive agents that warrant further explorations.
Biomass dynamics of charophyte-dominated submerged macrophyte communities in Myall Lake, NSW, Australia
(2008-01) Shilla, D.; Dativa, J.
The dynamics of submerged macrophytes were studied in a large and shallow near-pristine lake in New South Wales, Australia. The objectives were to investigate the seasonal dynamics in biomass of Chara fibrosa, Nitella hyalina and Najas marina both in time and space, and to characterise the underlying relationship between the plant biomass and both the gyttja and water depths. Charophytes were most densely grown in the north-east bays of the lake compared to the north-west bays. Average biomass of Chara fibrosa was highest at the north-east bays of this lake (e.g. 210 g d.w m−2) followed by north-west bays (e.g. 148 g d.w/m2), South-west bays (e.g. 60 g d.w/m2) and lastly central deep area of the lake (e.g. 31 g d./m2). A similar trend was displayed by Nitella hyalina biomass where at the north-east bays the biomass was the highest (e.g. 167 g d.w m−2) followed by north-west bays (e.g. 128 g d.w/m2), south-west bays (e.g. 38 g d.w/m2) and central deep area of the lake (e.g. 23 g d.w/m2). During the summer season the maximum total biomass of charophytes at Corrigans bay was recorded (e.g. 300 g d.w/m2), mostly being dominated by Nitella hyalina. Total biomass of charophyte was reduced during the winter season (e.g. 50 g d.w m−2). Najas marina biomass remained low both in time and space except in May at Bibby harbour and Shelly beach where its biomass peaked (e.g. 276 and 175 g d.w m−2 respectively). Gyttja depth showed a positive relationship with total charophyte biomass (r2 = 0.70; p<0.01) and it seemed to favour the growth of charophytes at the expense of other submerged macrophytes, e.g. Myriophyllum sp. and Vallisneria sp. Water depth displayed a negative relationship with total charophyte biomass (r2=−0.94; p<0.01). Both Chara fibrosa and Nitella hyalina correlated positively with gyttja depth (r , r; p<0.01) and negatively with water depth (r, r; p<0.01). Najas marina correlated positively only with water depth (r2=0.67, p<0.01).
Biota uptake of pesticides by selected plant species; the case study of Kilombero sugarcane plantations in Morogoro Region, Tanzania
(2010-01) Zacharia, James T.; Kishimba, Michael A.; Masahiko, Hayashi
This paper reports on biota uptake of pesticides by selected plant species from soil in which they are grown. The study was conducted at Kilombero sugarcane plantations and environs, Morogoro Region, Tanzania. Three species of the plant materials were collected namely sugarcane (Saccharum officinarum), guinea grass (Panicum maximum) and mango leaves (Mangifera indica). The sugarcane and guinea grass were used to reveal the plant uptake in the plantations whereas mango leaves were used to represent the environs. GPC cleaned sample extracts were analysed by GC–ECD and GC–NPD and the results confirmed using GC–MS. A total of 16 different pesticide residues were detected in soil samples and only 11 pesticide residues were detected in flora samples. o,p′-DDT had the highest concentration of all detected pesticides in soil samples with a mean concentration of 21.04 μg/kg d.w. whereas the highest concentrations of 17.16 μg/kg d.w. was recorded for p,p′-DDD in flora samples. The other DDT metabolites detected in soil samples were p,p′-DDT, p,p′-DDE, o,p′-DDE, p,p′-DDD and o,p′-DDD with concentration ranging from 2.00 to 18.30 μg/kg d.w. whereas the other pesticides detected in flora samples were p,p′-DDT α-endosulfan and γ-HCH with a mean concentration range of 3.21 to 13.54 μg/kg d.w. The paired sample t-test showed no significant difference between the concentrations of pesticides in flora and those found in soil.
Bis(piperidinedithiocarbamato)pyridinecadmium(II) as a Single-Source Precursor for the Synthesis of CdS Nanoparticles and Aerosol-Assisted Chemical Vapour Deposition (AACVD) of CdS thin films
(2014) Lewis, David J.; Revaprasadu, Neerish; Mlowe, Sixberth; Malik, Azad; Mubofu, Egid B.; O'Brien, Paul; Raftery, James
The synthesis and single-crystal X-ray structure of bis(piperidinedithiocarbamato)pyridinecadmium(II), [Cd(S2C(NC5H10))2(NC5H5)] are reported and its use as a precursor for the synthesis of hexagonal CdS nanoparticles and CdS thin films is presented. Thermogravimetric analysis (TGA) of this complex showed clean decomposition in two steps to give CdS. Thermolysis of the complex in hexadecylamine at different temperatures in the range 190 ¬ 270 °C gave CdS nanostructures including nanorods and oval shaped particles. The band gap of the as-synthesized CdS nanoparticles varied as the temperature was increased. CdS thin films with optical direct band gaps of ca. 2.4 eV were deposited by aerosol-assisted chemical vapour deposition (AACVD) in the temperature range 350 to 450 oC using the same precursor. Powder X-ray diffraction (p-XRD) patterns of CdS nanoparticles and thin films confirmed the hexagonal phase of CdS.

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