487 research outputs found
Control concepts for the alleviation of windshears and gusts
Automatic control system design methods for gust and shear alleviation were studied. It is shown that automatic gust/shear alleviation systems can be quite effective if both throttle and elevator are used in harmony to produce the forces and moments required to counter the effects of the windshear. Regulation with respect to ground speed or airspeed results in very similar system designs. The application of the NASA total energy probe in the detection of windshear and criteria for alleviation is considered. The theory and application of robust output observers is extended. Design examples show how implementation of the control laws can be accomplished using observers, and thereby resulting in less complex control system configurations
Maternal inheritance for grain iron and zinc densities in pearl millet
Genetic variation and inheritance of micronutrients in pearl
millet has largely been studied in recent years as part of
biofortification initiatives. In this study, maternal (reciprocal)
effect on inheritance of grain Fe and Zn was studied using
a set of diverse breeding material. Entries were paired for
low and high for Fe density to produce direct and reciprocal
crosses. Over two-seasons, Fe density among parents
varied 31-64 mg kg–1 and Zn density varied 28-43 mg kg–1.
Difference between each direct and reciprocal crosses for
Fe (1 to 4 mg kg–1) and Zn (0 to 2 mg kg–1) were negligible
and non-significant, hence cytoplasmic or maternal genes
are not likely to modify inheritance of these traits. These
results indicate that high Fe/Zn inbred can be used either
as female or male parent in hybrid-parent breeding program
Breeding Cultivars for Heat Stress Tolerance in Staple Food Crops
Food and nutritional security will be worsened by climate change-induced high temperatures, droughts and reduced water availability in most agricultural food crops environments, particularly in developing countries. Recent evidences indicate that countries in the southern hemisphere are more vulnerable to food production due to greater frequency of extreme weather events. These challenges can be addressed by: (i) adoption of climate mitigation tools in agricultural and urban activities; (ii) development of heat and drought tolerant cultivars in major food crops; (iii) bringing back forgotten native minor food crops such as millets and root crops; and (iv) continued investment in agricultural research and development with the strong government policy support on native crops grown by small holder farmers. The native crops have inherent potential and traits to cope with adverse climate during the course of its evolution process. Therefore, diversifying the crops should be a prime framework of the climate-smart agriculture to meet the global food and nutritional security for which policy-driven production changes are highly required in developing countries. The adverse effects of climate change on agricultural production need to be addressed by multidisciplinary team and approaches through strong network of research consortium including private sectors and multinational governments for global impact
Dendrimers as a Novel Carrier in Anti-HIV Therapy
The present treatments for HIV transfection include chemical agents and gene therapies. Although many chemical drugs, peptides and genes have been developed for HIV inhibition, a variety of non-ignorable drawbacks limited the efficiency of these materials. Dendrimers has ability to carrier of antiviral drugs due to some properties such as mono-dispersity, defined structure, amenability for functionalization using diverse ligands and its low-nanometer size. In this review, we discuss the application of dendrimers as both therapeutic agents and non-viral vectors of chemical agents and genes for HIV treatment. In one way, dendrimers with functional end groups combine with the gp120 of HIV and CD4 molecule of host cell to suppress the attachment of HIV to the host cell. In another way, dendrimers are also able to transfer chemical drugs and genes into the host cells, which increase the anti-HIV activity of these materials. Dendrimers as therapeutic tools provide a potential treatment for HIV infection.
Keywords: Dendrimers, Drug release, Drug targeting, gp120, CD4, Antiviral dru
Light interception and radiation use efficiency (RUE) in maize (Zea mays. L) intercropping with greengram (Vigna radiata L.)
Intercropping is growing two or more crop species simultaneously, different canopy architectures by row configuration, changing light interception, radiation utilisation, and increased yield. The present study aimed to evaluate different intercropping systems affected light interception per cent and radiation use efficiency in maize (Zea mays L.) intercropping with greengram (Vigna radiata L.) different ratios. Field experiments were conducted for Kharif 2022 and Rabi 2022-2023 seasons, which were laid out in a split-plot design and replicated three times. Three Nitrogen levels viz., N1 - 75 % RDN (Recommended dose of Nitrogen), N2 – 100% RDN, N3-125% RDN had taken as the main plot and three intercropping treatments were taken as subplot viz., M2G2- replacement series (two row of maize and two row of Greengram), M4G2- replacement series (four rows of maize and two row of Greengram), M2G3-paired row system (two rows of maize and three rows of Greengram), and sole maize. Both light interception and radiation use efficiency were significantly affected by intercropping systems. Light interception per cent of the main crop (maize) was significantly higher (69.0, 75.5 and 71.0 % during Kharif and 60.1, 78.1 and 76.6 during rabi) at vegetative, flowering and maturity phases, respectively. The Kharif 2022 and Rabi 2022-2023 maximum Radiation Use Efficiency (RUE) of Maize intercropping with green gram (maize + greengram) was higher in T12 (M2G3 paired row with 125 % Recommended Dose of Nitrogen) recorded as 2.46 (Kharif) and 1.43 (rabi). The outcome might be utilised to optimise the row configuration of intercropping design, explain the mechanism of intercropping on light utilisation, and improve radiation use efficiency
Hydrogen storage in carbon nanotubes and related materials
Adsorption of hydrogen at 300 K has been investigated on well-characterized samples of carbon nanotubes, besides carbon fibres by taking care to avoid many of the pitfalls generally encountered in such measurements. The nanotube samples include single- and multi-walled nanotubes prepared by different methods, as well as aligned bundles of multi-walled nanotubes. The effect of acid treatment of the nanotubes has been examined. A maximum adsorption of ca. 3.7 wt% is found with aligned multi-walled nanotubes. Electrochemical hydrogen storage measurements have also been carried out on the nanotube samples and the results are similar to those found by gas adsorption measurements
Genomics-Integrated Breeding for Carotenoids and Folates in Staple Cereal Grains to Reduce Malnutrition
Globally, two billion people suffer from micronutrient deficiencies. Cereal grains provide
more than 50% of the daily requirement of calories in human diets, but they often
fail to provide adequate essential minerals and vitamins. Cereal crop production in
developing countries achieved remarkable yield gains through the efforts of the Green
Revolution (117% in rice, 30% in wheat, 530% in maize, and 188% in pearl millet).
However, modern varieties are often deficient in essential micronutrients compared
to traditional varieties and land races. Breeding for nutritional quality in staple cereals
is a challenging task; however, biofortification initiatives combined with genomic tools
increase the feasibility. Current biofortification breeding activities include improving rice
(for zinc), wheat (for zinc), maize (for provitamin A), and pearl millet (for iron and zinc).
Biofortification is a sustainable approach to enrich staple cereals with provitamin A,
carotenoids, and folates. Significant genetic variation has been found for provitamin A
(96–850 mg and 12–1780 mg in 100 g in wheat and maize, respectively), carotenoids
(558–6730 mg in maize), and folates in rice (11–51 mg) and wheat (32.3–89.1 mg)
in 100 g. This indicates the prospects for biofortification breeding. Several QTLs
associated with carotenoids and folates have been identified in major cereals, and the
most promising of these are presented here. Breeding for essential nutrition should be
a core objective of next-generation crop breeding. This review synthesizes the available
literature on folates, provitamin A, and carotenoids in rice, wheat, maize, and pearl
millet, including genetic variation, trait discovery, QTL identification, gene introgressions,
and the strategy of genomics-assisted biofortification for these traits. Recent evidence
shows that genomics-assisted breeding for grain nutrition in rice, wheat, maize, and
pearl millet crops have good potential to aid in the alleviation of micronutrient malnutrition
in many developing countries
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