Effect of canker size on availability of cassava planting materials in Nigeria

Cassava (Manihot esculenta L.) production is highly limited by cassava anthracnose disease (CAD) which causes significant losses in planting materials. An experiment was laid out at Ihiagwa, Owern in Nigeria with eighteen treatments replicated three times. Disease severity was scored on a scale of 1-5, and disease incidence was recorded as the percentage of infected plants in each host plant line. In all the three trials, TMS 30211 (425 mm) had cankers high up on the stem, showing that they were infected later in life. This will lead to more disease - freestems. Cultivars Akwakwuru (39.6 mm2), TMS 30555 (31.6 mm2), and Nwaocha (43.7 mm2), had the large canker size on whole plant, young stem, shoot and maturing stem. These cultivars had low resistance to anthracnose. In all the trials, TMS 4(2)1425, and TMS 30211, had the smallest canker size (1.80 and 6.3 mm2, respectively) on whole plant, young stems, shoots and maturing stems. TMS 4(2)1425 and TMS 30211 had higher resistance to anthracnose and can be recommended for further improvement through breeding, because plants producing smaller – size lesions survive much longer and would also mature and produce flowers needed for breeding for improving resistance to CAD and other diseases

Modification of the hydration products of hydrated cement paste by fly ash, β-cyclodextrin and fly ash-β-cyclodextrin composite

Abstract: Studies on the modification of the hydration products of fly ash (FA), β-cyclodextrin (β-CD) and fly ash-β-cyclodextrin (FA-β-CD) composite cement paste samples as hydration progressed were done using X-ray diffraction analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. This paper investigates the effect of FA, β-CD and FA-β-CD composite on the hydration and pozzolanic reactions. It was evident from all the analyses that β-CD improved the hydration reaction from the 7  day hydration period, while improvement on pozzolanic reaction was revealed from the 28  day hydration period. The study contributed to the knowledge of FA performance as a composite with cyclodextrin and promoted the continued inclusion of FA in concrete

Effect of a Synthetically Modified Natural Zeolite Additive on Properties and Durability of Cement Mortars

Abstract: Durability characteristics of cement mortars and concrete are of interest to various researchers and practitioners in the field of construction materials engineering. This study evaluated the potential use of a semi-synthetic zeolite additive for improvement of cement mortar properties. The product, a blend of selected alkaloids and zeolite is commercially available and effectively used in soil stabilization for road construction. However, its influence and effectiveness on properties of cementitious systems has not been explored. Emphasis of this study was on durability of cement mortars. This was assessed using the durability index approach being advanced in South Africa. The additive was added to standard mortars of 0.5 water-cement ratio, prepared according to EN 196, in proportions of 0%, 0.4%, 0.6%, 0.8%, 1.0%, and 2.5%. Tests carried out include compressive strength, oxygen permeability, sorptivity and resistance to sulphate attack. It was found that the additive significantly improves durability characteristics while increasing strength and workability when used at optimum proportions. Its use in proportions between 0.4 to 0.6% additive gave optimum results in most tests. Further increase in the additive proportion tends to be counter effective, especially at above 1% additive. The low optimum proportions found also favour economic considerations

The effect of fly ash, β-cyclodextrin and fly ash-β-cyclodextrin composites on concrete workability and strength

Abstract: To increase the use of fly ash (FA) as a pozzolanic material in concrete, a composite was formed with an interaction of FA with β-cyclodextrin (β-CD). Further research was carried out in this article to study the effects of replacing cement with FA (30% and 50% by mass), β-CD (0.025%, 0.05% and 0.1%) and FA-β-CD composite on the workability and strength of concrete. Workability was assessed by means of the slump test and strengths were assessed using the compressive and split tensile strength tests. Higher combined contents of FA and β- CD resulted in increased workability of concrete of up to approximately 550 %. Furthermore, the inclusion of β-CD generally increased both the compressive and tensile strengths of the concretes not containing FA by up to 10 %. When combined with FA, the β-CD resulted in increased compressive strengths of up to 63 % and tensile strengths of up to 28 %, compared to the relevant pozzolanic concretes which did not include β-CD. The study contributed to the knowledge of FA performance using cyclodextrin and promoted the continued inclusion of FA in concrete, which in turn should reduce the environmental pollution resulting from FA

Incidence of leaf blight disease of Egusi melon in South-west Nigeria

Egusi melon ( Citrullus lanatus (Thumb) Mansf.) is an important vegetable crop grown for edible seeds and oil in West Africa. Leaf Blight Disease (LBD) is one of the major constraints to its production, with potential to cause economic damage. The objective of this study was to investigate the incidence and distribution of leaf blight on Egusi melon in Southwestern Nigeria. A survey of LBD of Egusi melon was conducted in 2015 and 2016, in five southwestern States of Nigeria (Ogun, Oyo, Osun, Ekiti and Ondo States). Twenty plants each, were randomly sampled from 150 farms comprising 30 farms each, from each State. The distribution of different Egusi melon varieties planted was recorded. \u201cBara\u201d cv. was the most cultivated variety (51.6%); followed by \u201cBojuri\u201d (30.4%) and \u201cSerewe\u201d (18%). Leaf blight was observed in most farms in the five States, from 73% in Osun and Oyo states to 83% in Ondo State. Disease incidence and severity varied with locations and cultivars, and ranged from 0.0-87.5\ub118% and 1.0\ub10-4.5\ub10.8 in Osun State to 20.0\ub119 - 95.0\ub14.5% and 2.3\ub11.5 - 5.0\ub10 in Ondo State. Out of the twelve fungal pathogens from ten genera isolated from infected plants, only Colletotrichum truncatum , C. gloeosporioides and Lasiodiplodia theobromae caused Leaf blight on Egusi melon.Le melon Egusi ( Citrullus lanatus (Thumb) Mansf.) Est une importante culture l\ue9gumi\ue8re cultiv\ue9e pour les graines et l\u2019huile comestibles en Afrique de l\u2019Ouest. La maladie de br\ufblure foliaire (LBD) est l\u2019une des principales contraintes \ue0 sa production, avec le potentiel de causer des dommages \ue9conomiques. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9tudier l\u2019incidence et la distribution de la br\ufblure foliaire du melon Egusi dans le Sud-ouest du Nig\ue9ria. Une enqu\ueate sur la LBD du melon Egusi a \ue9t\ue9 faite en 2015 et 2016, dans cinq \uc9tats du sud-ouest du Nig\ue9ria (\uc9tats d\u2019Ogun, Oyo, Osun, Ekiti et Ondo). Vingt plantes dans chaque \uc9tat ont \ue9t\ue9 \ue9chantillonn\ue9es au hasard dans 150 fermes comprenant 30 fermes chacune, de chaque \uc9tat. La distribution des diff\ue9rentes vari\ue9t\ue9s de melons Egusi plant\ue9es a \ue9t\ue9 enregistr\ue9e. \uabBara\ubb cv. \ue9tait la vari\ue9t\ue9 la plus cultiv\ue9e (51,6%); suivi de \uabBojuri\ubb (30,4%) et \uabSerewe\ubb (18%). La br\ufblure foliaire a \ue9t\ue9 observ\ue9e dans la plupart des exploitations agricoles des cinq \uc9tats, passant de 73% dans les \uc9tats d\u2019Osun et d\u2019Oyo \ue0 83% dans l\u2019\uc9tat d\u2019Ondo. L\u2019incidence et la gravit\ue9 de la maladie variaient selon les emplacements et les cultivars, et allaient de 0,0-87,5 \ub1 18% et 1,0 \ub1 0-4,5 \ub1 0,8 dans l\u2019\uc9tat d\u2019Osun \ue0 20,0 \ub1 19 - 95,0 \ub1 4,5% et 2,3 \ub1 1,5 - 5,0 \ub1 0 dans l\u2019\uc9tat d\u2019Ondo . Sur les douze agents pathog\ue8nes fongiques de dix genres isol\ue9s de plantes infect\ue9es, seuls Colletotrichum truncatum , C. gloeosporioides et Lasiodiplodia theobromae ont caus\ue9 la br\ufblure foliaire du melon Egusi

Environmental distribution and genetic diversity of vegetative compatibility groups determine biocontrol strategies to mitigate aflatoxin contamination of maize by Aspergillus flavus

Published online: 27 Oct 2015Maize infected by aflatoxin-producing Aspergillus flavus may become contaminated with aflatoxins, and as a result, threaten human health, food security and farmers’ income in developing countries where maize is a staple. Environmental distribution and genetic diversity of A. flavus can influence the effectiveness of atoxigenic isolates in mitigating aflatoxin contamination. However, such information has not been used to facilitate selection and deployment of atoxigenic isolates. A total of 35 isolates of A. flavus isolated from maize samples collected from three agroecological zones of Nigeria were used in this study. Ecophysiological characteristics, distribution and genetic diversity of the isolates were determined to identify vegetative compatibility groups (VCGs). The generated data were used to inform selection and deployment of native atoxigenic isolates to mitigate aflatoxin contamination in maize. In co-inoculation with toxigenic isolates, atoxigenic isolates reduced aflatoxin contamination in grain by > 96%. A total of 25 VCGs were inferred from the collected isolates based on complementation tests involving nitrate non-utilizing (nit−) mutants. To determine genetic diversity and distribution of VCGs across agroecological zones, 832 nit− mutants from 52 locations in 11 administrative districts were paired with one self-complementary nitrate auxotroph tester-pair for each VCG. Atoxigenic VCGs accounted for 81.1% of the 153 positive complementations recorded. Genetic diversity of VCGs was highest in the derived savannah agro-ecological zone (H = 2.61) compared with the southern Guinea savannah (H = 1.90) and northern Guinea savannah (H = 0.94) zones. Genetic richness (H = 2.60) and evenness (E5 = 0.96) of VCGs were high across all agro-ecological zones. Ten VCGs (40%) had members restricted to the original location of isolation, whereas 15 VCGs (60%) had members located between the original source of isolation and a distance > 400 km away. The present study identified widely distributed VCGs in Nigeria such as AV0222, AV3279, AV3304 and AV16127, whose atoxigenic members can be deployed for a region-wide biocontrol of toxigenic isolates to reduce aflatoxin contamination in maize

The effect of Fly ash, Beta-cyclodextrin and Fly ash-Beta-cyclodextrin composites on cement paste’s viscosity and setting times

Abstract: The possibility of increasing the usage of Fly ash (FA) in concrete has been a subject of interest and investigation by the authors. In the previous work, a composite of Fly ash- β- cyclodextrin (FA-β-CD) has been seen to have the tendencies of improving hydration reaction. To have further insight on how this composite can affect the mechanical properties of concrete, its rheological properties (viscosity and setting time) are assessed in this article. FA was used in percentages of 30 and 50, while β-CD was used in 0.025, 0.05 and 0.1 percentages. These percentages were based on the total percentage of cement (by mass). The results showed that increased in FA and β-CD contents, reduced the viscosity of the cement paste. Also, higher contents of FA and β-CD, reduced the water required for consistency and extended the setting times

The effect of dry wastewater sludge as sand replacement on concrete strengths

Abstract

Investigation of the fly ash - β cyclodextrin composite on concrete’s durability indexes

Abstract: Concrete quality can be assessed by its ability to withstand its design life without failing, which is a function of its strength and durability. The effect of fly ash (FA)-β- cyclodextrin (β-CD) composite on concrete’s durability indexes was investigated in this paper. Two durability index tests (oxygen permeability and sorptivity) were used for the assessment. FA (30% and 50% by mass of cement), β-CD (0.025%, 0.05% and 0.1%) and FA-β-CD composite were incorporated in the concrete mix. Twenty four different concrete mixes were investigated at 0.5 water-binder ratio (W/B) and 0.4 W/B. The tests were performed on the concrete samples after being cured for 28 and 90 days. The results showed that β-CD and FA-β-CD composite decrease oxygen permeability and sorptivity of concrete when used at optimum percentages

Using Matlab/Simulink Software Package to Investigate Fault Behaviors in HVDC System

Existing studies show that several performance issues will arise in the HVDC link during the three phase-to-ground fault at the side of the inverter and that the DC voltage will oscillate around zero and will not affect the rectifier of the AC system though the inverter of the AC system, and the AC voltages will become zero and the AC currents will show high amplitude as well as minor disturbances. It has also been argued that when the fault is applied on a single-phase to ground fault at the inverter side on the AC side, the voltage will decrease. In this paper, we focus on single line-to-ground fault, double line-to-ground fault, and three phase-to-ground fault at the inverter of the AC system and their behavior on the DC link as well as on the AC system of the rectifier with detailed simulations. A high voltage direct current (HVDC) Monopolar system is modeled using a Matlab/Simulink software package for the research. The results show that during the three phase-to-ground fault at the AC system of the inverter, the DC voltage will increase with a bogus waveform and the currents of the AC system at the rectifier will collapse to zero.At the double phase-to-ground fault level, the DC voltage will experience an increase in waveform while the currents of the AC system of the rectifier will experience different disturbances. At the single phase-to-ground fault level, the DC voltage will remain stable and the rectifier side of the AC system will also experience a stable state for both currents and voltages. © 2022 by the authors.Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ–2022-0031The research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) is gratefully acknowledged. Grant number: FEUZ–2022-0031