Measurement of actual efficacy of compact fluorescent lamps (CFLs)

The use of compact fluorescent lamps (CFLs) in domestic residences has increased rapidly due to their higher energy efficiency and longer life expectancy when compared with traditional incandescent light bulbs. Through measurement of illuminance, actual power and apparent power, the actual efficacy and associated power factor of CFLs are studied in this paper. It is found that for an individual CFL, although its power consumption and lighting output (i.e. luminous flux) may be higher or lower than the stated values provided by the lighting manufacturers, the actual efficacy would most likely be equal to or better than the efficacy calculated from the given rated power and lumen from the manufacturers. The typical power factor for CFLs was 0.63.

Green-fluorescent protein facilitates rapid in vivo detection of genetically transformed plant cells

Early detection of plant transformation events is necessary for the rapid establishment and optimization of plant transformation protocols. We have assessed modified versions of the green fluorescent protein (GFP) from Aequorea victoria as early reporters of plant transformation using a dissecting fluorescence microscope with appropriate filters. Gfp-expressing cells from four different plant species (sugarcane, maize, lettuce, and tobacco) were readily distinguished, following either Agrobacterium-mediated or particle bombardment-mediated transformation. The identification of gfp-expressing sugarcane cells allowed for the elimination of a high proportion of non-expressing explants and also enabled visual selection of dividing transgenic cells, an early step in the generation of transgenic organisms. The recovery of transgenic cell clusters was streamlined by the ability to visualize gfp-expressing tissues in vitro.

Sodium and lithium storage properties of spray-dried molybdenum disulfide-graphene hierarchical microspheres

Developing nano/micro-structures which can effectively upgrade the intriguing properties of electrode materials for energy storage devices is always a key research topic. Ultrathin nanosheets were proved to be one of the potential nanostructures due to their high specific surface area, good active contact areas and porous channels. Herein, we report a unique hierarchical micro-spherical morphology of well-stacked and completely miscible molybdenum disulfide (MoS2) nanosheets and graphene sheets, were successfully synthesized via a simple and industrial scale spray-drying technique to take the advantages of both MoS2 and graphene in terms of their high practical capacity values and high electronic conductivity, respectively. Computational studies were performed to understand the interfacial behaviour of MoS2 and graphene, which proves high stability of the composite with high interfacial binding energy (−2.02 eV) among them. Further, the lithium and sodium storage properties have been tested and reveal excellent cyclic stability over 250 and 500 cycles, respectively, with the highest initial capacity values of 1300 mAh g−1 and 640 mAh g−1 at 0.1 A g−1.

The potential for production of freeze-dried oral vaccines using alginate hydrogel microspheres as protein carriers

Oral administration of dry vaccine formulations is acknowledged to offer major clinical and logistical benefits by eliminating the cold chain required for liquid preparations. A model antigen, bovine serum albumin (BSA) was encapsulated in alginate microspheres using aerosolisation. Hydrated microspheres 25 to 65 μm in size with protein loading of 3.3 % w/w were obtained. Environmental scanning electron microscopy indicated a stabilizing effect of encapsulated protein on alginate hydrogels revealed by an increase in dehydration resistance. Freeze drying of alginate microspheres without use of a cryoprotectant resulted in fragmentation and subsequent rapid loss of the majority of the protein load in simulated intestinal fluid in 2 h, whereas intact microspheres were observed following freeze-drying of BSA-loaded microspheres in the presence of maltodextrin. BSA release from freeze-dried preparations was limited to less than 7 % in simulated gastric fluid over 2 h, while 90 % of the protein load was gradually released in simulated intestinal fluid over 10 h. SDS-PAGE analysis indicated that released BSA largely preserved its molecular weight. These findings demonstrate the potential for manufacturing freeze-dried oral vaccines using alginate microspheres.

A novel fluorescent probe involving a graphene quantum dot-enzyme hybrid system for the analysis of hydroquinone in the presence of toxic resorcinol and catechol

An efficient method for the analysis of hydroquinone at trace levels in water samples has been developed in the form of a fluorescent probe based on graphene quantum dots (GQDs). The analytical variable, fluorescence quenching, was generated from the formation of benzoquinone intermediates, which formed during the catalytic oxidation of hydroquinone by horseradish peroxidase (HRP). In general, the reaction mechanism involved hydroquinone, as an electron acceptor, which affected the surface state of GQDs via an electron transfer effect. The water-soluble GQDs were directly prepared by the pyrolysis of citric acid and with the use of the mentioned hybrid enzyme system, the detection limit for hydroquinone was as low as 8.4 × 10−8 M. Furthermore, this analysis was almost unaffected by other phenol and quinine compounds, such as phenol, resorcinol and other quinines, and therefore, the developed GQD method produced satisfactory results for the analysis of hydroquinone in several different lake water samples.

Fluorescent labelling of strychnine: A novel approach for recognition of strychnine binding sites on neuronal membrane

trychnine was coupled to fluorescein isothiocyanate to mark strychnine binding sites in spinal cord of rat. Specific binding of strychnine could be demonstrated in synaptosomal fraction. Addition of glycine to the strychninised membrane led to a decrease in fluorescence indicating same receptor loci.

A one-tube fluorescent assay for the quarantine detection and identification of Tilletia indica and other grass bunts in wheat

A molecular assay with enhanced specificity and sensitivity has been developed to assist in the surveillance of Karnal bunt, a quarantineable disease with a significant impact on international trade. The protocol involves the release of DNA from spores, PCR amplification to enrich Tilletia-specific templates from released DNA and a five-plex, real-time PCR assay to detect, identify and distinguish T. indica and other Tilletia species (T. walkeri, T. ehrhartae, T. horrida and a group comprising T. caries, T. laevis, T. contraversa, T. bromi and T. fusca) in wheat grains. This fluorescent molecular tool has a detection sensitivity of one spore and thus bypasses the germination step, which in the current protocol is required for confirmation when only a few spores have been found in grain samples. The assay contains five dual-labelled, species-specific probes and associated species-specific primer pairs in a PCR mix in one tube. The different amplification products are detected simultaneously by five different fluorescence spectra. This specific and sensitive assay with reduced labour and reagent requirements makes it an effective and economically sustainable tool to be used in a Karnal bunt surveillance program. This protocol will also be valuable for the identification of some contaminant Tilletia sp. in wheat grains.

Characterisation of the efficacy of endodontic medications using a three-dimensional fluorescent tooth model: An ex vivo study

The purpose of this study was to establish a three-dimensional fluorescent tooth model to investigate bacterial viability against intra-canal medicaments across the thickness and surface of root dentine. Dental microbial biofilms (Enterococcus faecalis and Streptococcus mutans) were established on the external root surface and bacterial kill was monitored over time against intra-canal medicament (Ca(OH)2 ) using fluorescent microscopy in conjunction with BacLight SYTO9 and propidium iodide stains. An Olympus digital camera fitted to SZX16 fluorescent microscope captured images of bacterial cells in biofilms on the external root surface. Viability of biofilm was measured by calculating the total pixel area of green (viable bacteria) and red (non-viable bacteria) for each image using ImageJ® software. All data generated were assessed for normality and then analysed using a Mann-Whitney t-test. The viability of S. mutans biofilm following Ca(OH)2 treatment showed a significant decline compared with the untreated group (P = 0.0418). No significant difference was seen for E. faecalis biofilm between the Ca(OH)2 and untreated groups indicating Ca(OH)2 medicament is ineffective against E. faecalis biofilm. This novel three-dimensional fluorescent biofilm model provides a new clinically relevant tool for testing of medicaments against dental biofilms.

Fluorescence And Nmr-Studies Of The Binding Of Cholinergic Fluorescent-Probes To Horse Serum-Cholinesterase

The interaction of the cholinergic fluorescent probes, 1-(5-dimethyl-aminoaphthalene-1-sulfonamido) ethane-2-trimethylammonium perchlorate, 1-(5-dimethylaminonaphthalene-1-sulfonamido) pentane-5-trimethylammonium tartarate and 1-(5-dimethylaminonaphthalene-1-sulfonamido) decane-10- trimethylammonium tartarate with horse serum cholinesterase has been examined by fluorescence and n.m.r. methods. Fluorescence titrations show binding of the decane derivative to two sites on the protein whereas the lower homologs bind largely to one site. Active site inhibitors like curbamylcholine and decamethonium abolish binding of the decane derivative to the high affinity site. The inhibitors are largely without effect on the binding of the lower homologs. N.m.r. studies clearly establish immobilization of both ends of the molecule on binding in the case of the decane derivative, whereas in the lower homologs the dimethylamino group on the naphthalene ring is significantly more affected in the presence of enzyme. The probes are effective inhibitors of the enzyme with the decane derivative being two orders of magnitude more effective than its lower homologs. Based on the n.m.r., fluorescence and inhibition studies, a model for probe binding to the enzyme is advanced. It appears that the decane derivative binds with high affinity to the catalytic anionic site while the lower affinity site is assigned to a peripheral anionic site. The lower homologs probe only the peripheral site. A comparison of fluorescence, n.m.r. and inhibition studies with acetylcholinesterases from electric eel and bovine erythrocytes is presented.

Fluorescent alamethicin fragments A study of membrane activity and aqueous phase aggregation

The linear polypeptide antibiotic alamethicin is known to form channels in artificial lipid membranes. Synthetic 13- and 17-residue alamethicin fragments, labelled with a fluorescent dansyl group at the N-terminus, have been shown to translocate divalent cations across phospholipid membranes and to uncouple oxidative phosphorylation in rat liver mitochondria, in a manner analogous to the parent peptides. From studies of the aqueous phase aggregation behavior of the peptides, as well as their interaction with rat liver mitochondria, it is concluded that the interaction of the peptides with membranes is a complex process, probably involving both aqueous and membrane phase aggregation.

Fluorescent probe and NMR studies of the aggregation of bile salts in aqueous solution

The binding of the fluorescent probes 1-anilino-8-naphthalene sulfonate and dansyl cadaverine to the sodium salts of cholic, deoxycholic and dehydrocholic acids has been investigated. Enhanced probe solubilisation accompanies aggregation. Monitoring of fluorescence intensities as a function of bile salt concentration permits the detection of primary micelle formation, as well as secondary association. The transition concentrations obtained by fluorescence are in good agreement with values determined for the critical micelle concentrations, by other methods. Differences in the behaviour of cholate and deoxycholate have been noted. Fluorescence polarisation studies of 1,6-diphenyl-1,3,5-hexatriene solubilised in bile salt micelles suggest a higher microviscosity for the interior of the deoxycholate micelle as compared to cholate. 1H NMR studies of deoxycholate over the range 1–100 mg/ml suggest that micelle formation leads to a greater immobilisation of the C18 and C19 methyl groups as compared to the C21 methyl group. Well resolved 13C resonances are observed for all three steroids even at high concentration. Both fluorescence and NMR studies confirm that dehydrocholate does not aggregate.

Studies on bicuculline binding sites on neuronal membrane using fluorescent antibody technique: Comparative binding of gaba and bicuculline

Highly purified fluorescent labelled anti-bicuculline antibodies were used to mark bicuculline binding sites in cerebral cortex of monkey brain. Specific binding of bicuculline could be demonstrated in the synaptosomal fraction, when bicuculline was added both Image and Image . Addition of γ-aminobutyric acid (GABA) to the bicucullinised membrane led to a decrease in fluorescence indicating same receptor loci and establishing GABA-bicuculline antagonism at a molecular level.

Marking one-summer old whitefish with fluorescent pigment spraying method and results of whitefish stockings in the Gulf of Bothnia

Anadromous whitefish is one of the most important fish species in the Finnish coastal fisheries in the Gulf fo Bothnia. To compensate the lost reproduction due to river damming and to support the fisheries, several million one-summer old whitefish are released yearly into the Gulf of Bothnia. Since there are naturally reproducing whitefish in the Gulf as well, and the wild and stocked fish can not be separated in the catch, stocking impact can only be estimated by marking the stocked fish. Due to the small size and large number of released whitefish, the scattered fishery and large area where the whitefish migrate, most of the traditionally used fish marking methods were either unsuitable (e.g. Carlin-tags) or proved to be too expensive (e.g. coded wire tags). Fluorescent pigment spraying method offers a fast and cost-effective method to mass-mark young fish. However, the results are not always satisfactory due to low long-time retention of the marks in some species. The method has to be tested and proper marking conditions and methods determined for each species. This thesis is based on work that was accomplished while developing the fluorescent pigment spraying method for marking one-summer old whitefish fingerlings, and it draws together the results of mass-marking whitefish fingerlings that were released in the Gulf of Bothnia. Fluorescent pigment spraying method is suitable for one-summer old whitefish larger than 8 cm total length. The water temperature during the marking should not exceed 10o C. Suitable spraying pressure is 6 bars measured in the compressor outlet, and the distance of the spraying gun nozzle should be ca 20 cm from the fish. Under such conditions, the marking results in long-term retention of the mark with low or no mortality. The stress level of the fish (measured as muscle water content) rises during the marking procedure, but if the fish are allowed to recover after marking, the overall stress level remains within the limits observed in normal fish handling during the capture-loading-transport-stocking procedure. The marked whitefish fingerlings are released into the sea at larger size and later in the season than the wild whitefish. However, the stocked individuals migrate to the southern feeding grounds in a similar pattern to the wild ones. The catch produced by whitefish stocking in the Gulf of Bothnia varied between released fingerling groups, but was within the limits reported elsewhere in Finland. The releases in the southern Bothnian Bay resulted in a larger catch than those made in the northern Bothnian Bay. The size of the released fingerlings seemed to have some effect on survival of the fish during the first winter in the sea. However, when the different marking groups were compared, the mean fingerling size was not related to stocking success.