Monilinia fructicola intercepted on Prunus spp. imported from Spain into South Africa between 2010 and 2020

The international trade of plants and their products, such as fresh fruits, can facilitate the introduction and spread of foreign pests and diseases. We examined South Africa’s import of stone fruits (Prunus spp.) as a pathway for introducing Monilinia fructicola (G. Wint.) Honey and document recommended phytosanitary measures to deal with the risk associated with its exportation into the country. Fresh fruits of Prunus spp. are imported from various countries. The current study provides a report on 10 years (2010–2020) importation of Prunus spp. from Spain to South Africa with associated cases of M. fructicola. We also detail the current management measures for imported stone fruits from Spain to South Africa. We report 18 M. fructicola detections that were found during the study period. The number of detections presents enough trends to determine the level of phytosanitary concerns regarding the importation of Prunus spp. fresh fruit from Spain, which cannot be neglected. M. fructicola is an economically important brown rot on many fruit hosts and potentially threatens agricultural and horticultural industries, the environment, and biodiversity in South Africa. The importation of Prunus spp. requires intensive management strategies for M. fructicola, as pathogens may pose a major phytosanitary concern because it could thrive and reproduce in various environmental conditions and on various host plants in South Africa. Therefore, if M. fructicola establishes in South Africa, its impacts will have consequences for different key socio-economic sectors, including the agricultural industry. Significance:• Monilinia fructicola is a pest of quarantine significance for South Africa.• If not managed properly, the importation of Prunus spp. with associated M. fructicola will be a significant phytosanitary concern that could cause severe economic impacts on the South African agricultural industry

A Novel Approach to Molecular Recognition Surface of Magnetic Nanoparticles Based on Host–Guest Effect

A novel route has been developed to prepared β-cyclodextrin (β-CD) functionalized magnetic nanoparticles (MNPs). The MNPs were first modified with monotosyl-poly(ethylene glycol) (PEG) silane and then tosyl units were displaced by amino-β-CD through the nucleophilic substitution reaction. The monotosyl-PEG silane was synthesized by modifying a PEG diol to form the corresponding monotosyl-PEG, followed by a reaction with 3-isocyanatopropyltriethoxysilane (IPTS). The success of the synthesis of the monotosyl-PEG silane was confirmed with1H NMR and Fourier transform infrared (FTIR) spectroscopy. The analysis of FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the immobilization of β-CD onto MNPs. Transmission electron microscopy (TEM) indicated that the β-CD functionalized MNPs were mostly present as individual nonclustered units in water. The number of β-CD molecules immobilized on each MNP was about 240 according to the thermogravimetric analysis (TGA) results. The as-prepared β-CD functionalized MNPs were used to detect dopamine with the assistance of a magnet

Monilinia fructicola intercepted on Prunus spp. imported from Spain into South Africa between 2010 and 2020

The international trade of plants and their products, such as fresh fruits, can facilitate the introduction and spread of foreign pests and diseases. We examined South Africa’s import of stone fruits (Prunus spp.) as a pathway for introducing Monilinia fructicola (G. Wint.) Honey and document recommended phytosanitary measures to deal with the risk associated with its exportation into the country. Fresh fruits of Prunus spp. are imported from various countries. The current study provides a report on 10 years (2010–2020) importation of Prunus spp. from Spain to South Africa with associated cases of M. fructicola. We also detail the current management measures for imported stone fruits from Spain to South Africa. We report 18 M. fructicola detections that were found during the study period. The number of detections presents enough trends to determine the level of phytosanitary concerns regarding the importation of Prunus spp. fresh fruit from Spain, which cannot be neglected. M. fructicola is an economically important brown rot on many fruit hosts and potentially threatens agricultural and horticultural industries, the environment, and biodiversity in South Africa. The importation of Prunus spp. requires intensive management strategies for M. fructicola, as pathogens may pose a major phytosanitary concern because it could thrive and reproduce in various environmental conditions and on various host plants in South Africa. Therefore, if M. fructicola establishes in South Africa, its impacts will have consequences for different key socioeconomic sectors, including the agricultural industry. Significance: Monilinia fructicola is a pest of quarantine significance for South Africa. If not managed properly, the importation of Prunus with associated M. fructicola will be a significant phytosanitary concern that could cause severe economic impacts on the South African agricultural industry

Dichloro (bis[diphenylthiourea]) cadmium complex as a precursor for HDA-capped CdS nanoparticles and their solubility in water

A single-source precursor route has been explored by using the diphenylthiourea cadmium complex as the source of cadmium sulphide (CdS) nanoparticles. The reaction was carried out using hexadecylamine (HDA) as the solvent and stabilising agent for the particles. The phenylthiourea complex was synthesised and characterised by means of a combination of spectroscopic techniques, microanalysis and X-ray crystal structural analysis. The diphenylthiourea complex was thermolysed in HDA at 120 °C for 1 h to produce CdS nanoparticles. The CdS nanoparticles prepared were made water-soluble via a ligand exchange reaction involving the use of pyridine to displace HDA. The pyridine was, in turn, replaced by glucose and glucuronic acid. The absorption and emission spectra showed the typical features of quantum confinement for the nanoparticles for both HDA-capped and glucose- or glucuronic acid-capped CdS nanoparticles. The change in the capping groups, from HDA to glucose and glucuronic acid, resulted in absorption and emission features that were almost similar, with only slight red-shifting and tailing

Electron transfer kinetics at single nanoparticles

The understanding and control of charge transfer at the very smallest scale is fundamental to nanoscience for applications such as catalysis and energy storage. However, the quantitative measurement of the kinetics of electron transfer at the nanoscale at individual free nanoparticles has not hitherto been possible. Here we describe experiments to unambiguously determine the electron transfer kinetics for the reduction of protons at single gold and silver nanoparticles of radii 7-15 nm. We show that there is a true "nano effect" (a kinetic acceleration due to the size of the nanoparticle) for this reaction at silver nanoparticles, but not at gold nanoparticles. © 2012 Elsevier Ltd. All rights reserved

Phytosanitary risk associated with illegal importation of pest-infested commodities to the South African agricultural sector

We evaluated the phytosanitary risk associated with illegal importation of pest-infested plant commodities into South Africa. Samples were collected from different South African ports of entry over 8 years (2011 to 2019) and data were analysed descriptively using Statistical Software Package. Pests were frequently detected on commodity species such as Citrus (18.31%), Zea mays (13.22%), Phaseolus vulgaris (12.88%), Musa spp. (9.15%) and Fragaria ananassa (5.08%). The highest number of pests intercepted occurred on fresh fruits (44.06%), followed by grains (26.44%) and vegetables (14.23%). The most intercepted organisms were Callosobruchus rhodesianus (7.79%), Dysmicoccus brevipes (7.11%), Callosobruchus maculates (6.10%) and Phyllosticta citricarpa (4.74%). The majority of intercepted organisms were non-quarantine organisms (70.50%), followed by pests of unknown status (17.28%), quarantine pests (10.84%) and potential quarantine pests (1.35%). Phyllosticta citricarpa, Bactrocera dorsalis, Spodoptera frugiperda and Prostephanus truncatus were the only quarantine pests intercepted in terms of South African regulatory status. The interception was mainly from southern African countries, particularly Mozambique, Zimbabwe and Eswatini. The findings present the level of phytosanitary risk associated with illegal importation and/or non-compliance in regard to plants and plant commodities from different countries through South African ports of entry. Crop production, biodiversity, food security, existing export markets, and access to new export markets could be threatened as importing countries may impose stringent phytosanitary measures to limit the chances of introduction and establishment of quarantine pests into their territories. Significance Illegal importation of plant commodities may lead to the introduction, establishment and spread of pests that are of quarantine significance to South Africa. Introduction of pest species such as Phyllosticta citricarpa, Bactrocera dorsalis, Spodoptera frugiperda and Prostephanus truncatus into South Africa could result in undesirable impacts on the ecosystem, agriculture, biodiversity and economy of the country. Access to new export markets of plant commodities could be threatened as importing countries may impose stringent phytosanitary measures to limit the chances of introduction and establishment of these quarantine pests into their territories

Gold nanoparticles show electroactivity: counting and sorting nanoparticles upon impact with electrodes.

Gold nanoparticles (AuNPs) in aqueous 0.10 M HCl are shown to be electroactive at oxidising potentials greater than 1.0 V (vs. Ag/AgCl) by means of voltammetric monitoring of AuNP-electrode collisions. The method promises the use of anodic particle coulometry for the detection and characterisation of the AuNPs

Molecular Recognition by Calix[4]arene-Modified Gold Nanoparticles in Aqueous Solution

Extremely stable, water-soluble gold nanoparticles 3 capable of specific molecular recognition of pyridinium ions in aqueous systems are prepared. The particles are stabilized and solubilized by thioalkylated oligoethylene glycol ligands 1. Specific recognition was achieved by thiol-modified calixarene ligands 2. The strongly colored gold particles also served as readily detectable optical markers for the specific binding events