Determining the potential for smallholder organic production among three farming groups through the development of an empirical and participatory decision support tool.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.Organic farming is increasingly viewed as a plausible production system for sustainable agriculture for smallholder farmers. However, there is not enough scientific evidence and knowledge to advocate certified organic farming for African smallholder farmers who face several constraints related to production, storage and marketing. The potential for organic farming for smallholder farmers, faced by these constraints, is not clearly defined. As a result, this study set out to evaluate the production potential of organic agriculture among three smallholder farmer groups. Production questions were used to investigate and evaluate the potential for organic agriculture among three smallholder farmer groups and constituted the following subproblems: · What crops can be grown in the three study areas, based on climatic data ? · Do farmers concur that these are the most suitable potential organic crops? · How useful do the farmers find the decision making tool? · What constraints threaten commercial production of the identified crops for these farmers? Participatory methodologies that included the use of Force Field Analysis, discussions and workshops were used to identify organic production constraints related to production decisions. Farmers faced constraints related to finance, capacity enhancement, technical knowledge, fencing, irrigation, and a lack of, or inappropriately trained extension officers. As a response to identified production constraints, a decision support tool was developed. Natural resource data, including climatic and agronomic data, was used to create a specially calibrated Microsoft Excel spreadsheet interface that functions as an empirical organic production decision support tool for organic and aspirant organic smallholder farmers, by providing answers for farmer-prioritised production constraints. A list of potential crops for each of the three study areas was subjected to a series of checks against suitability for climate and disease conditions and nutrient requirements. A limited supply of manure, to meet the enormously high requirements for organic production in the poor soils of these areas, is the major constraint to exclusive organic production and renders certified organic production difficult and unsustainable. Farmers disagreed with some of the crops on the list, arguing that familiar crops were rejected by the model, but they were excited by the prospects for production of “new” crops suggested as suitable by the decision support tool, but not yet grown in the study areas. End users welcomed the model and expressed the opinion that it would be useful in decision making related to organic crop production. The study concludes that, although a number of agronomically-suitable crops can grow in the study areas, organic production is restricted by rather high manure requirements, lack of compost making skills, lack of knowledge on natural pest and disease control and poorly nourished soils, leading to poor yields. The rainy season creates a disease-supporting environment, rendering organic farming risky for rain-fed smallholder farming. Risk in certified organic farming for smallholders was further exacerbated by a hardly inconducive policy environment that low literacy levels exist amongst farmers. This study is innovative for three reasons. First, farmers were true participants and drivers of the research. Second, trans-disciplinary expert seminars were attended by experts from different disciplines who critiqued the conceptualisation, design, and implementation of the study. Third, the development of a practical decision-support tool shows innovation towards solving complex smallholder farmers decisions. If organic farming is to be promoted, commitment by government is needed in order to establish policy and legislation on organic farming to direct and govern training, information provision and marketing. Intensive training and knowledge building of organic production for smallholder farmers and extension officers is critical. There are also agroecological risks associated with organic farming for smallholder farmers. Recommendations for future research include comparison between organic agriculture and conventional agriculture, where sustainability of certified organic farming and economic viability can be conducted in the South African context. Improvement of the decision making tool will require involving information technology specialists so that the tool can be installed in community centres, extension offices and other accessible places for farmers and others

Phosphorylation of silk fibroins improves the cytocompatibility of silk fibroin derived materials: a platform for the production of tuneable material

Silk fibroin demonstrates great biocompatibility and is suitable for many biomedical applications, including tissue engineering and regenerative medicine. Current research focuses on manipulating the physico-chemical properties of fibroin, and examining the effect of this manipulation on firobin's biocompatibility. Regenerated silk fibroin was modified by in vitro enzymatic phosphorylation and cast into films. Films were produced by blending, at several ratios, the phosphorylated and un-phosphorylated fibroin solutions. Fourier transform infra-red spectroscopy was used to determine the specific P–OH vibration peak, confirming the phosphorylation of the regenerated silk fibroin solution. Differential scanning calorimetry showed that phosphorylation altered the intra- and inter-molecular interactions. Further experiments demonstrated that phosphorylation can be used to tailor the hydrophylicity/hydrophobicity ratio as well as the crystalinity of silk fibroin films. Release profiling of a model drug was highly dependent on silk modification level. Cytotoxicity assays showed that exposure to lixiviates of phosphorylated films only slightly affected cellular metabolism and proliferation, although direct contact resulted in a strong direct correlation between phosphorylation level and cell proliferation. This new method for tuning silk biomaterials to obtain specific structural and biochemical features can be adapted for a wide range of applications. Phosphorylation of silk fibroins may be applied to improve the cytocompatibility of any silk-based device that is considered to be in contact with live animals or human tissues.The authors would like to acknowledge the support granted to the authors by European NOVO Project, contract no. FP7-HEALTH 2011-two-stage 278402

Fabrication and Intermolecular Interactions of Silk Fibroin/Hydroxybutyl Chitosan Blended Nanofibers

The native extracellular matrix (ECM) is composed of a cross-linked porous network of multifibril collagens and glycosaminoglycans. Nanofibrous scaffolds of silk fibroin (SF) and hydroxybutyl chitosan (HBC) blends were fabricated using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and trifluoroacetic acid (TFA) as solvents to biomimic the native ECM via electrospinning. Scanning electronic microscope (SEM) showed that relatively uniform nanofibers could be obtained when 12% SF was blended with 6% HBC at the weight ratio of 50:50. Meanwhile, the average nanofibrous diameter increased when the content of HBC in SF/HBC blends was raised from 20% to 100%. Fourier transform infrared spectra (FTIR) and 13C nuclear magnetic resonance (NMR) showed SF and HBC molecules existed in hydrogen bonding interactions but HBC did not induce conformation of SF transforming from random coil form to β-sheet structure. X-ray diffraction (XRD) confirmed the different structure of SF/HBC blended nanofibers from both SF and HBC. Thermogravimetry-Differential thermogravimetry (TG-DTG) results demonstrated that the thermal stability of SF/HBC blend nanofibrous scaffolds was improved. The results indicated that the rearrangement of HBC and SF molecular chain formed a new structure due to stronger hydrogen bonding between SF and HBC. These electrospun SF/HBC blended nanofibers may provide an ideal tissue engineering scaffold and wound dressing

Histomorphology of Salivary Glands after Ligature and Reconstruction of Common Carotid Artery in Rabbits

Introduction. In occlusive diseases of carotid arteries may be involved salivary glands which play important role in oral and general homeostasis.Aim of the study. The purpose of this study was histomorphological evaluation of rabbit’s salivary glands after regional reduction af arterial circulation and reconstruction of ligated common carotid arteries comparing with normal histological sight.Materials and methods. The experiments were authorized by the Animal Ethics Committee of the Latvian Food and Veterinary Service. 20 male Californian rabbits weighing approximately 3 kg were used. Under intravenous general anesthesia and local anesthesia the ligature of a. carotis communis dextra was done. After 28 days 10 rabbits were sacrificed and samples were taken from all major salivary glands and histological measured acinar dimensions and acinar epithelial cell.For rest 10 rabbits under the general anesthesia were performed revascularization of a. carotis communis dextra. After 28 days the rabbits were sacrificed with intrapulmonal injection of T61. The acini dimensions and acinar epithelial cell diameter in microns in all glands were measured except buccal glands were measured. Results. In ischemic conditions all glands react with decrease of acinar epithelial cell diameter and also diametr of functional unit of salivary gland.After revascularisation reestablishment of acini and secretory epithelial cells was observed. Conclusions. Rabbit’s salivary glands have potential to recovery in diminished after ligation of ipsilateral common carotid artery size of acini and secretory epithelium after 4 week ischemia if the blood supply is reestabilished.publishersversionPeer reviewe

Glass transitions in native silk fibres studied by dynamic mechanical thermal analysis

Silks are a family of semi-crystalline structural materials, spun naturally by insects, spiders and even crustaceans. Compared to the characteristic β-sheet crystalline structure in silks, the non-crystalline structure and its composition deserves more attention as it is equally critical to the filaments' high toughness and strength. Here we further unravel the structure-property relationship in silks using Dynamic Mechanical Thermal Analysis (DMTA). This technique allows us to examine the most important structural relaxation event of the disordered structure the disordered structure, the glass transition (GT), in native silk fibres of the lepidopteran Bombyx mori and Antheraea pernyi and the spider Nephila edulis. The measured glass transition temperature Tg, loss tangent tan δ and dynamic storage modulus are quantitatively modelled based on Group Interaction Modelling (GIM). The "variability" issue in native silks can be conveniently explained by the different degrees of structural disorder as revealed by DMTA. The new insights will facilitate a more comprehensive understanding of the structure-property relations for a wide range of biopolymers

Effect of in vitro simulated gastro-duodenal digestion on the antioxidant and anti-inflammatory activity of South Africa Fynbos honey

Honey has been shown to have bioactivity. Fynbos (FB) honey was investigated for its bioactivity as this vegetation type is from a unique bio diverse region in the Cape Floristic Kingdom. Six FB and one medical grade Manuka (MAN) UMF 15+ honeys that were of quality grade (Codex Alimentarius) were used. Each honey sample was subjected to in vitro simulated gastro-duodenal digestion and the antioxidant and anti-inflammatory activity of each fraction was determined. These fractions were undigested/raw honey (UD), gastric digest (GD) and gastro-duodenal digest (GDD). Included were pH and digestive enzyme controls. The total polyphenol and the flavonoid content (TPC and TFC) were determined with the Folin-Ciocalteu (F-C) and aluminium chloride methods respectively. Antioxidant activity was measured with the trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) assays. Cellular antioxidant activity (CAA) in the Caco-2 and SC-1 cell lines using the dichloroflourescein diacetate (DCFH DA) assay was investigated. Nitric oxide (NO) scavenging activity was determined with the sodium nitroprusside (SNP) assay. Pro-inflammatory and anti-inflammatory effects of honey were evaluated in non-stimulated and stimulated with LPS/IFN γ murine macrophage RAW 264.7 cells, respectively. Cell viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was done. TPC and TFC of MAN were higher than that of FB honeys. With GD, TPC and TFC of MAN increased and following GDD, TPC decreased and TFC remained unchanged. In contrast TPC and TFC of FB honey were maintained with GD and GDD. TEAC assay revealed activity by MAN being higher than that of FB honeys. With GD digestion, the antioxidant activity of MAN was unchanged but following GDD, activity was reduced. For FB honeys, TEAC was maintained with GD and GDD. ORAC assay revealed that the activity of MAN was similar to that of FB. Digestion had no effect on activity of both MAN and FB honeys. CAA in the Caco-2 and SC-1 cell line was higher for MAN compared to FB honey. In both cell lines a similar trend was observed where with GD, CAA was unchanged while with GDD, CAA was reduced. This loss of CAA following GDD was found to be due to H2O2 formation as a result of polyphenol degradation in an alkaline environment containing sodium bicarbonate and pancreatin. NO scavenging activity of MAN was greater than FB. For both types of honey with GD, NO scavenging activity was unchanged and with GDD for MAN was reduced and for FB unchanged. Digestion showed an increased pro-inflammatory effect for MAN, FB1, FB2 and FB3. The UD fractions of MAN, FB1 and FB6 had anti-inflammatory effects. FB5 and FB6 honeys showed increased anti-inflammatory activity after GD and GDD. All honey fractions did not show any cytotoxicity. In conclusion, FB honey has antioxidant, pro- and anti-inflammatory properties. With digestion, GD activity was either increased or unchanged while with GDD activity was reduced, lost or unchanged. Observed effects were either due to pH and/or digestive enzyme activity. FB honey with its shown bioactivity could be an important local nutraceutical product.Dissertation (MSc)--University of Pretoria, 2017.AnatomyMScUnrestricte