Nanotechnology-based agrochemical delivery systems would ensure efficient and economical utilization of these very important agricultural inputs. In this study, mesoporous silica nanoparticles with particle diameters of -150 nm and pore sizes of -2.5 nm were synthesized via liquid crystal templating mechanism. Urea, as a model agrochemical molecule, was entrapped in the mesopores of the siliceous material by simple immersion loading using aqueous urea solutions. About 15.5% (w/w) of urea was loaded inside the pores mainly by physisorption while the total adsorption capacity of mesoporous silica nanoparticles could reach up to 80% (w/w). Highly concentrated urea solution was found to be more effective due to high driving concentration gradient generated. Release process of the urea-loaded mesoporous silica nanoparticles in water and soil indicated a two stage sustained slow release-profile. The findings for soil release studies revealed at least fivefold improvement in the release period. By the ability to entrap urea guest molecules into its mesopores and release them in a controlled manner, mesoporous silica nanoparticles demonstrated its great potential as a nanocarrier for agrochemicals.

In the recent decades, there has been a concern on heavy metals in waste water and high cost of conventional methods of removing heavy metals, for this reason search on adsorbents of biological origin which is low cost and efficient is necessary. In this work defatted Moringa oleifera seed powder was studied as a potential alternative adsorbent for removal of Cu(II) and Pb(II) from aqueous solution. Physicochemical parameters such as pH, contact time, adsorption kinetics and initial ions concentration adsorption capacity using sorption models were evaluated. The results showed that the optimum pH for biosorption of Cu(II) was 6.5 while that of Pb(II) was 5.5. Contact time for Cu(II) was observed to occur after 30 min while that of Pb(II) occurred after 40 min. FTIR analysis revealed that defatted Moringa oleifera seed biomass had presence of amino, carboxyl, hydroxyl and carbonyl groups, these groups were responsible for biosorption of Cu(II) and Pb(II) from aqueous solution. Biosorption kinetic data fitted well with pseudo-second-order kinetic model (r2 ≤ 0.9997) giving equilibrium rate constant (k2) of 0.0350±0.0275 g mg−1 min−1 for Cu (II) loaded biomass and 0.0206±0.0114 g mg−1 min−1 for Pb (II) loaded biomass; the biosorption isotherms for the biosorbent fitted well with Freundlich isotherm model than with Langmuir isotherm model. However, the separation factor RL of Langmuir model was between 0 and 1 indicating favourable sorption process and the low value of mean sorption energy of 9.19×10-2 kJ from D-R model showed that the forces of attraction involved were Van der Waal forces indicating the process of adsorption was physical adsorption. In conclusion, the study revealed that defatted Moringa oleifera seed is an efficient biosorbent for removal of Cu(II) and Pb(II) from aqueous solution.

We report here the synthesis and characterization of polydiacetylene (PDA) films and nanotubes using layer-by-layer (LBL) chemistry. 10,12-Docosadiyndioic acid (DCDA) monomer was selfassembled on flat surfaces and inside of nanoporous alumina templates. UV irradiation of DCDA provided polymerized-DCDA (PDCDA) films and nanotubes. We have used zirconium-carboxylate interlayer chemistry to synthesize PDCDA multilayers on flat surfaces and in nanoporous template. PDCDA multilayers were characterized using optical (UV-vis, fluorescence, ellipsometry, FTIR) spectroscopies, ionic current-voltage (I-V) analysis, and scanning electron microscopy. Ellipsometry, FTIR, electronic absorption and emission spectroscopies showed a uniform DCDA deposition at each deposition cycle. Our optical spectroscopic analysis indicates that carboxylatezirconium interlinking chemistry is robust. To explain the disorganization in the alkyl portion of PDCDA multilayer films, we propose carboxylate-zirconium interlinkages act as "locks" in between PDCDA layers which restrict the movement of alkyl portion in the films. Because of this locking, the induced-stresses in the polymer chains can not be efficiently relieved. Our ionic resistance data from I-V analysis correlate well with calculated resistance at smaller number of PDCDA layers but significantly deviated for thicker PDCDA nanotubes. These differences were attributed to ionblocking because some of the PDCDA nanotubes were totally closed and the nonohmic and permselective ionic behaviors when the diameter of the pores approaches the double-layer thickness of the solution inside of the nanotubes.

The herbs Carissa spinarum, Physalis minima and Toddalia asiatica have traditionally been used in healing diabetes, malaria and pneumonia by the communities around the Kisii region, Kenya. However in the available literature, there is scanty information on effectiveness of different plant parts of the herbs in healing the ailments. The objective of this study was to investigate the potential antimicrobial and antifungal activity of methanolic extract of whole plant Physalis minima, leaf and root of Carissa spinarum and Toddalia asiatica against gram positive bacteria Staphylococcus aureus (ATCC 25923), gram negative bacteria Escherichia coli (ATCC 25922) and fungus Candida albicans (ATCC14053). Antibiotic disc methicillin, cotrimoxazole, chloramphenicol, gentamicin, ampicillin, nalidixic and nitrofurantoin were used in the study. In each herb, plant part was extracted by soaking in methanol/dichloromethane in ratio 1:1 for a week, filtered, concentrated by rotary vapor and cooled. The same process was repeated three times for all samples. The study was conducted by agar well diffusion method. Methanolic root extract of Toddalia asiatica showed highest antibacterial activity against Staphylococcus aureus (ATCC 25923), root extract of Carissa spinarum had highest antibacterial activity against Escherichia coli (ATCC 25922) while root extract of Toddalia asiatica showed highest antifungal activity. It was concluded that root extract of Toddalia asiatica showed highest antibacterial activity 16.7mm  against Staphylococcus aureus(ATCC 25923), root extract of Carissa spinarum had highest antibacterial activity 10 mm  against Escherichia coli (ATCC 25922)  while  root extract of Toddalia asiatica had highest antifungal activity 18 mm against Candida albicans.

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Maize is the main staple crop in the East African Mountains. Understanding how the edaphic characteristics change along altitudinal gradients is important for maximizing maize production in East African Highlands, which are the key maize production areas in the region. This study evaluated and compared the levels of some macro and micro-elements (Al, Ca, Fe, K, Mg, Mn, Na and P) and other soil parameters (pH, organic carbon content, soil texture [i.e. % Sand, % Clay and % Silt], cation exchange capacity [CEC], electric conductivity [EC], and water holding capacity [HC]). Soil samples were taken from maize plots along three altitudinal gradients in East African highlands (namely Machakos Hills, Taita Hills and Mount Kilimanjaro) characterized by graded changes in climatic conditions. For all transects, pH, Ca, K and Mg decreased with the increase in altitude. In contrast, % Silt, organic carbon content, Al and water holding capacity (HC) increased with increasing altitude. The research provides information on the status of the physical–chemical characteristics of soils along three altitudinal ranges of East African Highlands and includes data available for further research.

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Advanced oxidation processes using semiconducting photocatalysts for the degradation of organic pollutants are a promising approach for the remediation of pesticide-contaminated wastewater. High photodegradation efficiency and stability of the photocatalyst are of key importance for practical application of the semiconductor. In this study, mesoporous TiO/ZrO nanopowders were synthesized via two techniques; evaporation-induced self-assembly (EISA) and sol-gel using triblock copolymers Pluronic P123 and F127. The photodegradation activities of the composites were determined by employing the herbicide chloridazon as a model compound. Due to well-developed mesoporosity, the TiO/ZrO nanocomposite synthesized by EISA displays high surface area and small crystallite sizes leading to higher photocatalytic activity than pristine TiO prepared under similar condition and commercial Degussa P25 nanopowder. The optimum amount of zirconium required for the highest activities was identified and found to be 0.14 and 0.05 mol% for the EISA and sol-gel-prepared samples, respectively. Systematic studies of the post-thermal treatment step for both samples show that Zr inhibits an anatase-to-rutile phase transition only up to 600 °C, at higher temperature phase separation occurs. Samples synthesized by EISA method showed enhanced degradation activity than sol-gel-synthesized samples.