3 research outputs found
An in ovo investigation into the hepatotoxicity of cadmium and chromium evaluated with light-and transmission electron microscopy and electron energy-loss spectroscopy
Excessive agriculture, transport and mining often lead to the contamination of valuable water resources. Communities using this
water for drinking, washing, bathing and the irrigation of crops are continuously being exposed to these heavy metals. The most
vulnerable is the developing fetus. Cadmium (Cd) and chrome (Cr) were identified as two of the most prevalent heavy metal water
contaminants in South Africa. In this study, chicken embryos at the stage of early organogenesis were exposed to a single dosage of
0.430 mM physiological dosage (PD) and 430 mM (£1000 PD) CdCl2, as well as 0.476 mM (PD) and 746 mM (£1000 PD)
K2Cr2O7. At day 14, when all organ systems were completely developed, the embryos were terminated and the effect of these metals
on liver tissue and cellular morphology was determined with light- and transmission electron microscopy (TEM). The intracellular
localization of these metals was determined using electron energy-loss spectroscopy (EELS). With light microscopy, the PD of both
Cd and Cr had no effect on liver tissue or cellular morphology. At £1000 PD both Cd and Cr caused sinusoid dilation and tissue
necrosis. With TEM analysis, Cd exposed hepatocytes presented with irregular chromatin condensation, ruptured cellular
membranes and damaged or absent organelles. In contrast Cr caused only slight mitochondrial damage. EELS revealed the bioaccumulation
of Cd and Cr along the cristae of the mitochondria and chromatin of the nuclei.http://www.tandfonline.com/loi/lesa202016-12-01hb201
Comparative study: the effect of annealing conditions on the properties of P3HT:PCBM blends
This paper presents a detailed study on the role of various annealing treatments on organic poly(3-hexylthiophene) and [6]-phenyl-C61-butyric acid methyl ester blends under different experimental conditions. A combination of analytical tools is used to study the alteration of the phase separation, structure and photovoltaic properties of the P3HT:PCBM blend during the annealing process. Results showed that the thermal annealing yields PCBM ‘‘needle-like’’ crystals and that prolonged heat treatment leads to extensive phase separation, as demonstrated by the growth in the size and quantity of PCBM crystals. The substrate annealing method demonstrated an optimal morphology by eradicating and suppressing the formation of fullerene clusters across the film, resulting in longer P3HT fibrils with smaller diameter. Improved optical constants, PL quenching and a decrease in the P3HT optical bad-gap were demonstrated for the substrate annealed films due to the limited diffusion of the PCBM molecules. An effective strategy for determining an optimized morphology through substrate annealing treatment is therefore revealed for improved device efficiency.Web of Scienc
Synthetic Hemozoin (β-Hematin) Crystals Nucleate at the Surface of Neutral Lipid Droplets that Control Their Sizes
Emulsions
of monopalmitoylglycerol (MPG) and of a neutral lipid
blend (NLB), consisting of MPG, monostearoylglycerol, dipalmitoylglycerol,
dioleoylglycerol, and dilineoylglycerol (4:2:1:1:1), the composition
associated with hemozoin from the malaria parasite Plasmodium falciparum, have been used to mediate
the formation of β-hematin microcrystals. Transmission electron
microscopy (TEM), electron diffraction, and electron spectroscopic
imaging/electron energy loss spectroscopy (ESI/EELS) have been used
to characterize both the lipid emulsion and β-hematin crystals.
The latter have been compared with β-hematin formed at a pentanol/aqueous
interface and with hemozoin both within P. falciparum parasites and extracted from the parasites. When lipid and ferriprotoporphyrin
IX solutions in 1:9 v/v acetone/methanol were thoroughly premixed
either using an extruder or an ultrasound bath, β-hematin crystals
were found formed in intimate association with the lipid droplets.
These crystals resembled hemozoin crystals, with prominent {100} faces.
Lattice fringes in TEM indicated that these faces made contact with
the lipid surface. The average length of these crystals was 0.62 times
the average diameter of NLB droplets, and their size distributions
were statistically equivalent after 10 min incubation, suggesting
that the lipid droplets also controlled the sizes of the crystals.
This most closely resembles hemozoin formation in the helminth worm Schistosoma mansoni, while in P. falciparum, crystal formation appears to be associated with the much more gently
curved digestive vacuole membrane, which apparently leads to formation
of much larger hemozoin crystals, similar to those formed at the flat
pentanol–water interface