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Above-Ground Carbon Allometric Models for Diplorhynchus condylocarpon (Müll. Arg.) Pichon., A Common Miombo Woodland Associate
(2015-07) Mganga, Nyatwere D.; Lyaruu, Herbert V.M.; Banyikwa, Feetham F.
Estimation of carbon using allometric models facilitates sustainable management of forests and woodlands. Reliable estimations of carbon in most ecosystems can only be accomplished by using species-specific allometric models which are lacking for many species. The present study was carried out so as to develop the best fit above-ground carbon allometric models of various tree components; stems, branches, twigs and leaves of Diplorhynchus condylocarpon (Horn-pod tree), a species that is commonly associated with Miombo woodlands. Twenty one trees of D. condylocarpon with a ranging diameter at breast height (DBH) from 5 to 19 cm were destructively sampled from Miombo woodlands of Kitwe in Tanzania. Linear models were assessed for above-ground carbon using regression analysis. Regression analysis was carried out by relating above-ground carbon of tree components to DBH and height (H), using DBH and H as predictor variables. The best fit allometric models for above-ground carbon of total, stems, branches and twigs and/or leaves had coefficient of determination values (R2) of 0.98, 0.98, 0.96 and 0.79 respectively at P < 0.05. Above-ground carbon allometric models developed have wide application in sustainable use of the species and carbon accounting particularly in Central Zambezian Miombo woodlands without future destructive sampling.
Above-ground carbon stock in a forest subjected to decadal frequent fires in western Tanzania
(International Network for Natural Sciences, 2017-02-14) Mganga, Nyatwere D.; Lyaruu, Herbert V.; Banyikwa, Feetham F.
Gradual increase in atmospheric temperature due to elevated levels of greenhouse gases has become a global agenda. Of these gases, carbon dioxide is the most predominant accounting for more than half of the atmospheric warming. Conveniently, forests and woodlands are important sinks of carbon through sequestration which involves carbon dioxide capture and storage. Miombo woodlands are the most widespread savanna vegetation in the Sub-Saharan Africa, and like other vegetation they are likely to have a marked degree of carbon sequestration. However, these ecosystems are normally threatened by many disturbances, including outbreaks of uncontrolled and destructive fires. Yet, it has been reported that wildfires have both positive and negative influence on carbon sequestration in forests and woodlands. The aim of the present study was to determine tree carbon in Ilunde forest after consecutive exposure to frequent fires for 10 years. A fire suppressed forest of Kitwe was used as a control. Fire frequency of Ilunde forest was obtained from published Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery from the year 2001 to 2012. Tree carbon stock was estimated using biomass allometric models so far developed for miombo woodlands.The level of difference in carbon density between the two forests was determined using t-test. Tree carbon stock was significantly high in Kitwe forest than in Ilunde (P < 0.05). The effects of wildfires are variable depending on the nature of ecosystems and the existing circumstances. Since fire is crucial in miombo woodlands, then prescribed burning could be prioritized to sustain sinks of carbon.
Advances in D. melanoxylon Investigations towards Tissue Culture: Problems and Limitations
(American Journal of Plant Sciences,, 2014-11) Washa B. & A.M. Nyomora, Washa & Nyomora
The first attempt on D. melanoxylon tissue culture was conducted from 2010 to 2013 at a high level of expectations. A total of 500 seeds were sterilized at different concentration of reagents and inoculated at different strength of the Murashige and Skoog medium for germination to obtain disease free explants for callus induction trials. A total of 400 nodal segments obtained from germinated seeds were sterilized at different concentration of reagents and inoculated at different hormonal combinations to induce callus formation for seedling multiplication. Results from this tissue culture attempt set a foundation for tissue culture success in D. melanoxylon on the future research. Only 19.8% of seeds inoculated in half strength of Murashige and Skoog medium germinated within 7 days while only 6.8% of seeds inoculated in full strength of Murashige and Skoog medium germinated within 6 days. This germination was at sterilization of 20 minutes in 35% ethanol and 20 minutes in 2.6% sodium hypochlorite. A total of 1% of inoculated D. melanoxylon seedling fragments in Murashige and Skoog media supplemented with hormone combination at 2.0 mg/l BAP + 0.5 mg/l NAA developed callus after16 days from the inoculation day. The final weight of the callus at the last record was 0.62 g. In this induction ex-plants were surface sterilized in 35% ethanol for 20 minutes and 2.6% sodium hypochlorite solution for 20 minutes. The color of callus was green and friable in nature. Other hormonal combinations in this case did not induce callus production. These results suggested that the problems which affect seed germination in the natural environment are also reflected on germination in the Murashige and Skoog medium and in callus induction. Vulnerability to fungal attack is a limitation for successful callus induction and germination in the culture room. More research under improved sterile conditions is needed to improve callus percentage for seedling multiplication.
Aflatoxin levels in sunflower seeds and cakes collected from micro- and small-scale sunflower oil processors in Tanzania
(2017-04-18) Mmongoyo, Juma A.; Wu, Felicia; Linz, John E.; Nair, Muraleedharan G.; Mugula, Jovin K.; Tempelman, Robert J.; Strasburg, Gale M.
Aflatoxin, a mycotoxin found commonly in maize and peanuts worldwide, is associated with liver cancer, acute toxicosis, and growth impairment in humans and animals. In Tanzania, sunflower seeds are a source of snacks, cooking oil, and animal feed. These seeds are a potential source of aflatoxin contamination. However, reports on aflatoxin contamination in sunflower seeds and cakes are scarce. The objective of the current study was to determine total aflatoxin concentrations in sunflower seeds and cakes from small-scale oil processors across Tanzania. Samples of sunflower seeds (n = 90) and cakes (n = 92) were collected across two years, and analyzed for total aflatoxin concentrations using a direct competitive enzyme-linked immunosorbent assay (ELISA). For seed samples collected June-August 2014, the highest aflatoxin concentrations were from Dodoma (1.7–280.6 ng/g), Singida (1.4–261.8 ng/g), and Babati-Manyara (1.8–162.0 ng/g). The highest concentrations for cakes were from Mbeya (2.8–97.7 ng/g), Dodoma (1.9–88.2 ng/g), and Singida (2.0–34.3 ng/g). For seed samples collected August-October 2015, the highest concentrations were from Morogoro (2.8–662.7 ng/g), Singida (1.6–217.6 ng/g) and Mbeya (1.4–174.2 ng/g). The highest concentrations for cakes were from Morogoro (2.7–536.0 ng/g), Dodoma (1.4– 598.4 ng/g) and Singida (3.2–52.8 ng/g). In summary, humans and animals are potentially at high risk of exposure to aflatoxins through sunflower seeds and cakes from micro-scale millers in Tanzania; and location influences risk.
Aminated polyethersulfone-silver nanoparticles (AgNPs-APES) compositemembranes with controlled silver ion release for antibacterial and water treatment applications
(Materials Science and Engineering C, 2016-02-10) Haider, M. Salman; Shao, Godlisten N.; Imran, S.M; Park, Seongsoo; Abbas, Nadir; Tahir, M.S; Hussain, Manwar; Bae, Wookeun; Kim, HT
The present study reports the antibacterial disinfection properties of a series of silver nanoparticle (AgNP) immobilized membranes. Initially, polyethersulfone (PES) was functionalized through the introduction of amino groups to form aminated polyethersulfone (NH2-PES, APES). AgNPs were then coordinately immobilized on the surface of the APES composite membrane to formAgNPs-APES. The properties of the obtainedmembrane were examined by FT-IR, XPS, XRD, TGA, ICP-OES and SEM-EDAX analyses. These structural characterizations revealed that AgNPs ranging from 5 to 40 nm were immobilized on the surface of the polymer membrane. Antibacterial tests of the samples showed that the AgNPs-APES exhibited higher activity than the AgNPs-PES un-functionalized membrane. Generally, the AgNPs-APES 1 cm × 3 cm strip revealed a four times longer life than the un-functionalized AgNPs polymer membranes. The evaluation of the Ag+ leaching properties of the obtained samples indicated that approximately 30% of the AgNPs could be retained, even after 12 days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25 days. The present study provides a systematic and novel approach to synthesize water treatment membranes with controlled and improved silver (Ag+) release to enhance the lifetime of the membranes.
Anatomic Morphometrics of the “Senene” Tettigoniid Ruspolia differens Serville (Orthoptera: Conocephalidae) from North-West Tanzania
(Hindawi Publishing Corporation, 2012-12-20) Matojo, Nicodemus D.; Jacob, G. Yarro
e morphometrics of Ruspolia differens (order: Orthoptera; family: Conocephalidae), the longhorn grasshopper that is widely known as senene by its Kiswahili name, was largely unclear although the species serves broadly as a delicacy relish snack. In this study, the anatomic morphometrics of this insect was critically inferred based on the samples that were collected from North-west Tanzania in April-May 2009. R. differens was revealed to have a number of unique anatomic features that can essentially serve in its diagnosis. ese include the paired male metathoracic faps, finger-like prosternal protuberances, hind femoral spines, subequal tibial black markings, and an obvious male biased antennal dimorphism.
Antifungal activity, Lycopersicon esculentum, fungal skin infection, bioactives
(Taylor and Francis, 2020) Mlozi, Stephano Hanolo
Candida albicans and Cryptococcus neoformans are dangerous pathogens causing fungal diseases. C. albicans and C. neoformans developed resistance to fungicides such as fluconazole. Similarly, pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Salmonella typhi have become resistant to antibiotcs such as methicillin. Thus, searching for alternative antimicrobial agents is inevitable. Tephrosia vogelii used traditionally for management of fungal and bacterial diseases is potential source of antimicrobial agents. It is in this vein that, antimicrobial activities of leaf and root extracts of T. vogelii were evaluated against C. albicans (ATCC 90028), C. neoformans (clinical isolate), S. aureus (ATCC25923), E. coli (ATCC29953), K. pneumoniae (ATCC 700603) and S. typhi (NCTC 8385). A two-fold serial dilution method using the sterilised 96 wells of polystyrene microlitre plates used to determine the minimum inhibitory concentration (MIC) of extracts. Hexane and dichloromethane extracts exhibited the lowest activity against fungi strains with MICs >10 mg/mL. Root and leaf methanolic extracts exhibited activity at MICs of 5 and 1.25 mg/mL, respectively, against both tested fungi. Dichloromethane and methanolic extracts exhibited antibacterial activity with MICs ranging from 2.5 - 10 mg/mL and 0.625 - 5 mg/mL, respectively. Antimicrobial activities of the extracts of T. vogelii revealed potentiality of bioactives against fungal and bacterial diseases.
Antimicrobial activities of Tephrosia vogelii against selected pathogenic fungi and bacteria strains
(2019-12-19) Mlozi, Stephano H.; Mmongoyo, Juma A.; Chacha, Musa
Candida albicans and Cryptococcus neoformans are dangerous pathogens causing fungal dis eases. C. albicans and C. neoformans developed resistance to fungicides such as fluconazole. Similarly, pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Salmonella typhi have become resistant to antibiotcs such as methicillin. Thus, searching for alternative antimicrobial agents is inevitable. Tephrosia vogelii used traditionally for manage ment of fungal and bacterial diseases is potential source of antimicrobial agents. It is in this vein that, antimicrobial activities of leaf and root extracts of T. vogelii were evaluated against C. albicans (ATCC 90028), C. neoformans (clinical isolate), S. aureus (ATCC25923), E. coli (ATCC29953), K. pneumoniae (ATCC 700603) and S. typhi (NCTC 8385). A two-fold serial dilution method using the sterilised 96 wells of polystyrene microlitre plates used to determine the minimum inhibitory concentration (MIC) of extracts. Hexane and dichloromethane extracts exhibited the lowest activity against fungi strains with MICs >10 mg/mL. Root and leaf methanolic extracts exhibited activity at MICs of 5 and 1.25 mg/mL, respectively, against both tested fungi. Dichloromethane and methanolic extracts exhibited antibacterial activity with MICs ranging from 2.5 - 10 mg/mL and 0.625 - 5 mg/mL, respectively. Antimicrobial activities of the extracts of T. vogelii revealed potentiality of bioactives against fungal and bacterial diseases.
Antimicrobial activities of Tephrosia vogelii against selected pathogenic fungi and bacteria strains
(2020) Mlozi, Stephano Hanolo; Mmongoyo, Juma, A; Chacha, Musa
Candida albicans and Cryptococcus neoformans are dangerous pathogens causing fungal diseases. C. albicans and C. neoformans developed resistance to fungicides such as fluconazole. Similarly, pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Salmonella typhi have become resistant to antibiotcs such as methicillin. Thus, searching for alternative antimicrobial agents is inevitable. Tephrosia vogelii used traditionally for management of fungal and bacterial diseases is potential source of antimicrobial agents. It is in this vein that, antimicrobial activities of leaf and root extracts of T. vogelii were evaluated against C. albicans (ATCC 90028), C. neoformans (clinical isolate), S. aureus (ATCC25923), E. coli (ATCC29953), K. pneumoniae (ATCC 700603) and S. typhi (NCTC 8385). A two-fold serial dilution method using the sterilised 96 wells of polystyrene microlitre plates used to determine the minimum inhibitory concentration (MIC) of extracts. Hexane and dichloromethane extracts exhibited the lowest activity against fungi strains with MICs >10 mg/mL. Root and leaf methanolic extracts exhibited activity at MICs of 5 and 1.25 mg/mL, respectively, against both tested fungi. Dichloromethane and methanolic extracts exhibited antibacterial activity with MICs ranging from 2.5 - 10 mg/mL and 0.625 - 5 mg/mL, respectively. Antimicrobial activities of the extracts of T. vogelii revealed potentiality of bioactives against fungal and bacterial diseases.
Antimycobaterial and antibacterial activities of extracts from Caesalpinia bonduc ( L .) Roxb
(2017) Mlozi, Stephano Hanolo
Aim of study: The study focused on searching bioactives that can be used to combat pathogenic microbes from leaves, stem wood and stem bark of Caesalpinia bonduc Roxb. Background: Many pathogenic microbes have developed resistance to most of the recommended first line and second line drugs. Antimicrobial resistances endanger the control of infectious diseases by increasing morbidity and mortality and impose massive costs on societies in both developed and developing countries. Medicinal plants used for treatment of infectious diseases are potential of bioactives to combat this problem. Caesalpinia bonduc (L.) Roxb is ethnomedically used by communities in Africa and India but little is known on the bioactive compounds therefrom. In order to know the bioactive on other parts of this plant it contains, it was necessary to undertake phytochemical investigation and antimicrobial analysis of extracts. Material and Method: The plant materials of Caesalpinia bonduc were collected from Kisakasaka mangrove reserve, Zanzibar. Micro-organisms were collected from Department of Microbiology at MUHAS. Methanol, chloroform and n-hexane extracts from stem wood, stem bark and leaves of Caesalpinia bonduc were evaluated for antimicrobials. Antibacterial activity was evaluated against Staphylococcus aureus (ATCC25923), Escherichia coli (ATCC29953) and Pseudomonas aeruginosa (ATCC25922). Antimycobacterial activity was performed against two non-pathogenic mycobacteria species namely Mycobacteria indicus pranii and Mycobacteria madagascariense. The two-fold serial dilution method was used to evaluate MIC for antimicrobial activities. Chromatographic techniques employed in sequential extractions. Results: Extracts with high activity had MIC of 2.5 mg/mL while extracts with low activity had MIC of 5.0 mg/mL. Conclusion: Antimicrobial activity exhibited by extracts indicated that, Caesalpinia bonduc is a potential for bioactive metabolites which can be used as leads for the development of antimicrobial agents.
Applicability of Satellite Remote Sensing in Accounting Above-Ground Carbon in Miombo Woodlands
(2015-10) Mganga, Nyatwere D.; Lyaruu, Herbert V.M.
The crisis of climate change has drawn attention of ecologists all over the world to explore ways that could effectively enhance the sequestration of carbon in forests and woodlands. This necessitates forest inventory, along with knowledge of techniques that are quick and manageable. The present study was carried out in Miombo woodlands of western Tanzania namely, Kitwe and Mgaraganza. The aim of the present study was to investigate the effectiveness of remote sensing in estimating the stock of carbon in Miombo woodlands. Two types of data namely, ground-truthing and satellite imagery were used. Ground-truthing data were obtained by measuring the diameter at breast height (DBH) of all trees in 30 and 20 concentric plots in Kitwe and Mgaraganza forests, respectively. The average DBH of trees in each forest was fitted in biomass allometric models to estimate the ground-truthing vegetation biomass. On the other hand, Landsat images of the two forests were used to compute the Normalised Vegetation Index (NDVI). The computed NDVI were regressed with the ground-truthing vegetation biomass to get the remotely sensed vegetation biomass which was assumed to be 50% carbon. The coefficients of determination between the ground-truthing above-ground biomass and the NDVI values were statistically significant at P<0.05. The above-ground carbon stock obtained by ground-truthing in Mgaraganza and Kitwe forests was 3 and 2 times higher than that of satellite remotely sensed data respectively. The above-ground carbon stock obtained from satellite remote sensing gives some impression thus a basis for remote sensing in Miombo woodlands
Application of WRF Mesoscale Model for Prediction of Wind Energy Resources in Tanzania
(Elsevier, 2020-01-30) Kibona, Talam Enock
This study gives an overview of the wind energy resource distribution within and of the coast of Tanzania. Wind speed predictions using WRF model at 60 m a.g.l, which is typically the height of turbine hub, are compared with the wind speed values obtained by extrapolating Final Analysis (FNL) wind speed data at 10m a.g.l using power law. The WRF Model is used for 72-hours wind speed and direction forecasting where the initial boundary of the model is provided by Final Analysis data (FNL) available at UCAR with resolution of 1 × 1 degree. The WRF model has good results in comparison to power law because the variation is very small. At 1200 and 1800 hours over the areas near the land WRF predicts low wind speed than power law. WRF model predicts more offshore wind strength in the night than the noon. At 1300 to 1400 hrs the wind speed in the offshore part of Tanzania is mostly below 9 m/s as predicted by WRF model. Based on the limited studies, it has been observed that the wind energy potential exists in the offshore zones of Tanzania. This study encourage exploring the possibilities of harnessing the offshore wind energy potentials available in Tanzania. The approach adopted could be configuring WRF models with high horizontal resolution and many domains and carrying out detailed theoretical assessment of the wind energy resources, supplemented by actual measurements of the wind pattern using met-masts at different locations across and offshore of Tanzania.
Assessment of African Blackwood (Dalbergia melanoxylon) Population Structure in Kilwa District, Tanzania
(Tanzania Journal of Science, 2021-10-30) Washa B., Washa; Nyomora, Agnes; Nnungu, Stephen I
Overharvesting and limited conservation efforts have posed a serious threat to future availability of Dalbergia melanoxylon in Tanzania in recent years. The study was conducted between 2018 and 2020 covering Mitarure Forest Reserve (MFR) and 2 surrounding community forests of Ngea and Nambawala in Kilwa District. The purpose of the study was to assess the existing population status of the species in Tanzania. A total of 36 circular plots in Mitarure and 15 plots in each community forest were laid down. Data were recorded for the number of stems per plot, and then converted on per hectare basis where the basal area and densities per hectare were calculated. Data was disaggregated into 5 Diameter at Breast Height (DBH) generated distribution classes ranging from DBH 0 to more than 45 cm. The results revealed that, there was a contrast between the Mitarure Forest Reserve and community forests in terms of individual number of trees per unit area, basal area and densities. The numbers of stems per hectare for the species were found to be 16, 10 and 8 stems/ha in Mitarure, Ngea and Nambawala forest, respectively. Dalbergia melanoxylon in Mitarure forest was normally distributed. The respective basal area was over 80 m2 per ha in Nambawala against over 60 in MFR and Ngea. The results suggest success of the communities in conserving the species after previous overharvest. Authorities should frequently visit forests to increase the population of the species and reduce unauthorised harvesting.
ASSESSMENT OF INDOOR RADON-222 CONCENTRATIONS IN THE VICINITY OF MANYONI URANIUM DEPOSIT, SINGIDA
(Tanzania Journal of Science, 2018-05-23) Mlay, Germana; Makundi, Ismael
This study aimed to assess indoor radon concentrations in the vicinity of the Manyoni Uranium Deposit in Singida. The concentrations were measured for two months in 32 houses in the vicinity of Manyoni Uranium Deposit and 9 houses at Manyoni town using a portable radon gas monitor (Alpha –GUARDTM). The radon concentrations ranged from 27±3 to 518±28 Bq/m3with the overall mean of 166±12 Bq/m3 which is above recommended values of 100 Bq/m3 and 148 Bq/m3 set by WHO (World Health Organization) and EPA (Environmental Protection Agency's), respectively. The overall mean of indoor radon concentrations from each village were Kipondoda (169±13 Bq/m3), Muhalala (177±16 Bq/m3), Mwanzi, (287±13 Bq/m3), Mitoo (325±21 Bq/m3) and Majengo (377±23 Bq/m3) which exceed the limit set by WHO (World Health Organization) and EPA (Environmental Protection Agency). The value of 325±21 Bq/m3 and 377±23 Bq/m3 from Mitoo and Majengo respectively, exceed the limit of 300 Bq/m3 recommended by ICRP (International Commission on Radiation Protection). Thus there is a non-negligible probability of incurring stochastic effects for people living in the vicinity of Manyoni Uranium mine. It is recommended that human activities should be controlled near the uranium deposits and dwelings should be well ventilated.
Assessment on Potential of Cow Dung Manure in Zea mays Production at Kiwere Village in Iringa Rural District, Tanzania
(Scientific Research Publisher, 2020-11-27) Washa B, Washa
An assessment on potentiality of Cow dung manure in Zea mays production at Kiwere village in Iringa Rural District (7°37'17.3"S, 35°37'48.1"E) was conducted from December 2019 to June 2020. The idea of this assessment was influenced by soil fertility depletion and the fall of Maize production in Iringa region from 1990’s. A total of 10 farms, 5 farms for Cow dung manured and 5 for non-manured in which Maize growth was monitored for 6 months. Various parameters as height, width and weight of both Maize plants and Maize fruits were recorded. Soil qualities both chemical and physical characteristics were analysed and recorded but also weather (Temperature, humidity) together with soil pH were recorded throughout the assessment period. The p-value of <0.0001 (1.03702E-07) and <0.0001 (2.45684E-05) for height and width and the highest mineral chemical values in the Cow manured 10 plots indicated that Cow manure not only increase Maize production significantly but also supports the production of soil microbial and hence renewals the soil minerals and soil fertility as well. This is why the soil physical values in the Cow dung manured plots Organic matter, porosity, soil aeration and others were found to be higher and the soil comprised of Sandy Clay Loam. Farmers are strongly advised to use this multipurpose and potential manure in their unfertile soil. Cow manures are easily available in their environment and cheaper.
BET Study of Silver-Doped Silica Based on an Inexpensive Method
(Materials Letters, 2012-04-28) Hilonga, Askwar; Kim, Jong-gil; Sarawade, Pradip B.; Quang,Dang Viet; Shao, Godlisten N.; Elineema, Gideon; Kim, Hee Taik
The aimof this study is to identify an acid precursor that ismost desirable for the synthesis of sodiumsilicate-based silver-doped silica for large-scale industrial production. The final products were developed based on the presence of silver (silver-doped silica) or the absence of silver (pure silica). The properties of the obtained final products were examined using the BET method. This method involves characterization based on N2 physisorption studies to determine the surface area, pore diameter, and pore volume. Various graphs were plotted using the obtained data to describe the pore size distribution, isotherms, and the properties of hysteresis loops. Silver-doped silica with a BET surface area of up to 357 m2/g and a pore size of 5.4 nm was obtained using the most desirable precursors—sodium silicate and sulfuric acid. This is an unprecedented step toward synthesis of silver-doped silica fromdesirable precursors. This approach to the synthesis of silica with desirable propertieswithout involving sacrificial templates (surfactants) will be convenient for many applications and suitable for large-scale economic industrial production.
Bioactive compounds in Diospyros mafiensis roots inhibit growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus
(2017-01-20) Mmongoyo, J. A.; Nair, M.G.; Linz, J.E.; Wu, F.; Mugula, J.K.; Dissanayake, A.A.; Zhang, C.; Day, D.M.; Wee, J.M.; Strasburg, G.M.
Diospyros mafiensis F. White is a medicinal shrub or small tree (6 m tall) widely distributed in the ZanzibarInhambane regional mosaic and traditionally used to treat leprosy, diarrhoea, and skin fungal infections in Tanzania and Mozambique. Our objective was to determine the anti-aflatoxigenic properties of compounds from D. mafiensis root bark against vegetative growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus. Bioassay-guided extraction, fractionation, and isolation of bioactive compounds using A. parasiticus B62 were employed. The bioactive compounds were elucidated using 1H and 13CNMR and LC-MS. Growth inhibition was determined by measuring the colony diameter of A. flavus AF3357 and A. parasiticus SU-1 ATCC56775. Inhibitory effects on sporulation were estimated using a haemocytometer. Total aflatoxin was quantified by direct competitive enzyme-linked immunosorbent assay (ELISA). Bioactive compounds diosquinone (DQ) and 3-hydroxydiosquinone (3HDQ) were identified. DQ weakly inhibited A. flavus and A. parasiticus vegetative growth (MIC50 >100 µg/ml) and 3HDQ strongly inhibited A. flavus (MIC50 = 14.9 µg/ml) and A. parasiticus (MIC50 = 39.1 µg/ml). DQ strongly reduced total aflatoxin production by A. flavus from 157 to 36 ng/plate, and by A. parasiticus from 1,145 ng/plate to 45 ng/plate at 100 µg/ml. 3HDQ reduced total aflatoxin production by A. parasiticus from 1,145 to 32 ng/plate; stimulated production by A. flavus from 157 to 872 ng/plate at 12.5 µg/ml but reduced to 45 ng/plate at 100 µg/ ml. In summary, DQ and 3HDQ could be used as natural antifungal compounds to prevent mould growth and aflatoxin accumulation in food and feed.
Biodiesel production by sulfated mesoporous titania–silica catalysts synthesized by the sol–gel process from less expensive precursors
(Chemical Engineering Journal, 2012-11-21) Shao, Godlisten N.; Sheikh, Rizwan; Hilonga, Askwar; Lee, Jae Eun; Park, Yeung-Ho; Kim, HT
A sulfated titania–silica composite (S-TSC) was obtained through surface modification of mesoporous titania–silica composite synthesized using less expensive precursors; titanium oxychloride and sodium silicate as titania and silica sources respectively. A pre-formed titania sol facilitated the synthesis of a mesoporous composite with a high BET surface area (520 m2/g), suitable for surface modification using sulfuric acid to improve its catalytic performance. The materials synthesized via this process were examined by XRD, XRF, FTIR, SEM, TEM, TGA, and N2 physisorption studies. FTIR analysis showed the vibration band of the TiAOASi bond at 943 cm 1, suggesting the incorporation of titania into silica to form a composite. This vibration band was substantially shifted to 952 cm 1 after the attachment of the sulfate group. The catalytic activity of a series of as-prepared TSC, S-TSC calcined samples and pure H2SO4 were evaluated for esterification of oleic acid and transesterification of waste oil with methanol to yield methyl esters. It was observed that at these reaction conditions, S-TSC-450 and S-TSC-550 possessed high catalytic activity comparable to that of pure H2SO4 implying that surface modification of the titania–silica composite improves its acidic properties.
Biogas-slurry derived mesoporous carbon for supercapacitor applications
(Elsevier, 2017) Enock, Talam Kibona; King’ondu, Cecil K.; Pogrebnoi, Alexander; Jande, Yusufu Abeid Chande
This study reports on the transformation of biogas slurry into mesoporous carbon for supercapacitor electrodes. Pore structures have been modified by altering activation time, temperature and KOH/carbon mass ratio. The mesoporous carbons are successively developed as evidenced by type IV isotherms obtained in nitrogen sorption studies. BET, micropore and mesopore surface area of 515, 350, and 165 m2 g−1, respectively as well as a narrow pore width distribution of 3–4.5 nm are obtained. X-ray photoelectron results have confirmed the presence of functional groups of oxygen and nitrogen in the samples which facilitates the pseudocapacitance. The electrochemical measurements in 6 M KOH using a three electrode cell with Ag/AgCl as reference electrode and platinum as counter electrode has been performed. The materials activated at 700 °C, 3:1 KOH to carbon mass ratio, and for 120 min exhibit high specific capacitance of 289 F g−1 at a scan rate of 5 mV s−1. Shortening activation time to 30 and 60 min reduces specific capacitance to 163 and 182 F g−1, in that order. Additionally, at 3:1 KOH to carbon mass ratio and 60 min activation time, specific capacitances of 170 and 210 F g−1 at 600 and 800 °C, respectively are obtained. Moreover, specific capacitance increases with increasing the KOH to carbon mass ratio from 148 F g−1 for 1:1–163 F g−1 for 3:1 at 700 °C. Electrochemical impedance spectroscopy studies demonstrate that material has high conductivity. In addition; capacity retention of 96% after 20,000 cycles is shown at scan rate of 30 mV s−1. The study shows that high performance electrodes can be designed from biogas slurry derived porous carbon.
Biomass-based carbon electrode materials for capacitive deionization: a review
(Springer, 2019-06-27) Elisadiki, Joyce; Kibona, Talam Enock; Machunda, Revocatus L.; Saleem, Muhammad Wajid; Kim, Woo-Seung; Jande, Yusufu A. C.
Capacitive deionization (CDI) is a promising water purification technology which works by removing salt ions or charged species from aqueous solutions. Currently, most of the research on CDI focuses on the desalination of water with low or moderate salt concentration due to the low salt adsorption capacity of the electrodes. The electrosorption capacity of CDI relies on the structural and textural characteristics of the electrode materials. The cost of electrode materials, the complicated synthesis methods, and the environmental concerns arising from material synthesis steps hinder the development of large-scale CDI units. By considering the good electrical conductivity, high specific surface area (SSA), porous structure, availability, mass production, and cost, porous carbon derived from biomass materials may be a promising CDI electrode material. This review presents an update on carbon nanomaterials derived from various biomasses for CDI electrodes. It covers different synthesis methods and the electrosorption performance of each material and discusses the impact of the SSA and porous structure of the materials on desalination. This review shows that a variety of biomass materials can be used to synthesize cost-effective CDI electrode materials with different structures and good desalination performance. It also shows that diverse precursors and synthesis routes have significant influences on the properties and performance of the resulting carbon electrodes. Additionally, the performance of CDI does not depend only on BET surface area and pore structure but also on the applied voltage, initial concentration of the feed solution, and mass, as well as the capacitance of the electrodes.

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