A planetary boundaries perspective on the sustainability: resilience relationship in the Kenyan tea supply chain.

The purpose of this paper is to examine whether agricultural supply chains (ASC) can be simultaneously sustainable and resilient to ecological disruptions, using the Planetary Boundaries theory. The nine different Planetary Boundaries i.e. climatic change, biodiversity loss, biogeochemical, ocean acidification, land use, freshwater availability, stratosphere ozone depletion, atmospheric aerosols and chemical pollution are examined in relation to ASC sustainability and resilience. Kenya's tea upstream supply chain sustainability and resilience from the ecological point of view is questioned. This study adopts a multi-case study analysis approach of nine producer organisations from Kenya's tea supply chain. The data from the in-depth semi-structured interviews and a focus group discussion are analysed using thematic analysis. The Kenyan tea supply chain producers are not aware of all the nine planetary boundaries, although these impact on their resilience practices. They are engaged in pursuing both sustainability and resilience practices. They implement mainly environmental practices in relation to sustainability, while only a few of them are implementing resilience practices. The sustainability and resilience concepts were found to be interrelated, but resilience does not improve at the same pace as sustainability. It is suggested that the relationship between sustainability and resilience is non-linear. Limitations and future research avenues are also provided.

Brine shrimp cytotoxicity and antimalarial activity of plants traditionally used in treatment of malaria in Msambweni district.

CONTEXT: In Kenya, most people use traditional medicine and medicinal plants to treat many diseases including malaria. To manage malaria, new knowledge and products are needed. Traditional herbal medicine has constituted a good basis for antimalarial lead discovery and drug development. OBJECTIVES: To determine in vivo antimalarial activity and brine shrimp toxicity of five medicinal plants traditionally used to treat malaria in Msambweni district, Kenya. MATERIALS AND METHODS: A 0.2 ml saline solution of 100 mg/kg aqueous crude extracts from five different plant parts were administered orally once a day and evaluated for their in vivo chemosuppressive effect using Plasmodium berghei berghei-infected Swiss mice for four consecutive days. Their safety was also determined using Brine shrimp lethality test: Grewia trichocarpa Hochst ex A. Rich (Tiliaceae) root, Dicrostachys cinerea (L) Wight et Am (Mimosaceae) root, Tamarindus indica L. (Caesalpiniaceae) stem bark, Azadirachta indica (L) Burn. (Meliaceae) root bark, and Acacia seyal Del. (Mimosaceae) root. RESULTS: Parasitaemia was as follows: A. indica, 3.1%; D. cinerea, 6.3%; T. indica, 25.1%; A. seyal, 27.8%; and G. trichocarpa, 35.8%. In terms of toxicity, A. indica root bark extract had an LC50 of 285.8 µg/ml and was considered moderately toxic. T. indica stem bark extract and G. trichocarpa root extract had an LC50 of 516.4 and 545.8 µg/ml, respectively, and were considered to be weakly toxic while A. seyal and D. cinerea root extracts had a LC50 >1000 µg/ml and were, therefore, considered to be non-toxic. DISCUSSION AND CONCLUSION: All extracts had antimalarial activity that was not significant compared to chloroquine (p ≥ 0.05). No extract was toxic to the arthropod invertebrate, Artemia salina L. (Artemiidae) larvae, justifying the continued use of the plant parts to treat malaria.

Characterization of swellable molecularly imprinted polymer particles by surface plasmon resonance spectroscopy.

Surface plasmon resonance (SPR) has been used to investigate template binding at sites in theophylline-imprinted poly-[N-(N-propyl) acrylamide] particles. At concentrations as low as 10(-6) M theophylline, particle swelling is detected as a shift in the angle of minimum reflectance. The binding constant of theophylline estimated from the inflection point of the theophylline calibration curve is approximately 10,000. The imprinted polymer particles do not respond to caffeine or theobromine (which differs from theophylline by a single methyl group) at concentrations as high as 10(-2) M. Full-scale response of the imprinted polymer particles to theophylline (template) occurs in less than 15 minutes, and swelling is reversible. The immobilized imprinted polymer particles can undergo approximately 20 to 25 swelling and shrinking cycles before there is significant loss in functionality. A unique aspect of these imprinted polymer particles is that template binding causes the angle of minimum reflectance to decrease, not increase, in magnitude. Adsorption, which causes an increase in the angle of minimum reflectance, can be readily discriminated from template binding.

Swellable molecularly imprinted polyN-(N-propyl)acrylamide particles for detection of emerging organic contaminants using surface plasmon resonance spectroscopy.

Lightly crosslinked theophylline imprinted polyN-(N-propyl)acrylamide particles (ca. 300nm in diameter) that are designed to swell and shrink as a function of analyte concentration in aqueous media were spin coated onto a gold surface. The nanospheres responded selectively to the targeted analyte due to molecular imprinting. Chemical sensing was based on changes in the refractive index of the imprinted particles that accompanied swelling due to binding of the targeted analyte, which was detected using surface plasmon resonance (SPR) spectroscopy. Because swelling leads to an increase in the percentage of water in the polymer, the refractive index of the polymer nanospheres decreased as the particles swelled. In the presence of aqueous theophylline at concentrations as low as 10(-6)M, particle swelling is both pronounced and readily detectable. The full scale response of the imprinted particles to template occurs in less than 10min. Swelling is also reversible and independent of the ionic strength of the solution in contact with the polymer. Replicate precision is less than 10(-4) RI units. By comparison, there is no response to caffeine which is similar in structure to theophylline at concentrations as high as 1x10(-2)M. Changes in the refractive index of the imprinted polymer particles, as low as 10(-4) RI units could be readily detected. A unique aspect of the prepared particles is the use of light crosslinking rather than heavy crosslinking. This is a significant development as it indicates that heavy crosslinking is not entirely necessary for selectivity in molecular imprinting with polyacrylamides.