19672 research outputs found
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Study of interaction between cationic surfactant (CTAB) and paracetamol by electrical conductivity, tensiometric and spectroscopic methods
No full textThe interaction of a hydrophilic drug, paracetamol with the cationic surfactant cetyltrimethylammonium bromide (CTAB) in an aqueous media has been investigated by using conductometric, tensiometric and spectroscopic methods. The critical micelle concentration (CMC) values have been determined by two different methods and both the methods yielded identical CMC values. The experimental data of conductance and surface tension have been correlated against temperature and concentration using standard relations. The pseudophase separation model has been adopted for calculation of various thermodynamic parameters such as standard free energy ΔGm 0, enthalpy, ΔHmic 0, and entropy, ΔSmic 0, of micelle formation. The increase in the micellization with rising temperature is attributed towards the prevailing hydrophobic-hydrophobic increased interactions between the surfactant-drug aqueous mixtures. From the surface tension data the interfacial parameters such as the maximum surface excess concentration, Γmax, standard Gibbs free energy of adsorption at the air/solvent interface, ΔGad 0, and the minimum surface area pre molecule, Amin, were evaluated. Moreover, fourier transform infrared analysis (FTIR) was carried out to estimate the possible interactions prevailing in the miceller systems
Application of guar gum for the removal of dissolved lead from wastewater
No full textLead (Pb) is a toxic heavy metal with highly recalcitrant property. It easily accumulates in the food chain by interacting with calcium and iron components of the biomolecules of living organisms. The aim of the study was to develop an efficient method to treat heavy metal containing turbid wastewater without the introduction of any secondary source of pollutants. Guar gum, a long chain polysaccharide was used to remove Pb2+ from turbid wastewater containing kaolinite. Guar gum is extracted from the seed of leguminous shrub Cyamopsis tetragonoloba commonly known as guaran. Potassium alum, a commonly used inorganic coagulant was also studied in order to compare its Pb2+ removal efficiency with the biopolymer. It was observed that guar gum could achieve 83% removal, at an initial Pb concentration of 15 mg L−1. Optimization study using response surface methodology was used to determine the optimal process parameters. FTIR and zeta potential measurement of guar gum-Pb2+ aggregates were used to determine the removal mechanism. FTIR absorption peaks at 3618.79 cm−1 in the flocs indicate hydrogen bonding between Pb2+ and guar gum. Compact and well-formed flocs by guar gum are indicated by the SEM micrographs. In addition to the formation of compact sludge, guar gum is nontoxic and biodegradable and hence highly recommended for treatment of metal containing wastewater. The requirement of ultra-low amount of biopolymer in the range of 1.25 mg L−1 to treat the relatively high volume of water provides an additional financial advantage
A screen printed carbon electrode modified with carbon nanotubes and gold nanoparticles as a sensitive electrochemical sensor for determination of thiamphenicol residue in milk
No full textAntibiotic residues in milk are of great concern for health regulatory agencies, milk consumers, and dairy farmers due to their destructive effects, ranging from allergic reactions, antibiotic resistance and the ability to interfere with the production of fermented products (i.e. cheese and yogurt). Therefore, a reliable, fast, and simple method needs to be developed to monitor antibiotic residues in milk samples before distribution to consumers. In this study, the first sensitive electrochemical sensor is presented for the determination of thiamphenicol (TAP), a broad-spectrum antibiotic in bovine milk. In the fabrication process, a screen printed electrode (SPE) was modified with gold nanoparticles (AuNPs) and carbon nanotubes (CNTs) using ethylenediamine (en) as a cross linker. Cyclic voltammetry studies showed an adsorptive control process for the electro-oxidation of TAP at-0.1 V on the modified electrode of SPE/CNT/en/AuNPs. Differential pulse voltammetry (DPV) was applied for the quantitative determination of TAP under optimized conditions (0.1 M citrate buffer, pH 6.0, accumulation potential-0.7 V, and accumulation time 150 s). A DPV study for TAP shows a wide linear calibration range of 0.1-30 μM with the detection limit of 0.003 μM. Furthermore, the developed sensor displays high sensitivity, reproducibility, repeatability, and good stability for the detection of TAP. The proposed sensor was successfully applied for the determination of spiked TAP in bovine milk with satisfactory results
Quantifying the ultrastructure changes of air-dried and irradiated human amniotic membrane using atomic force microscopy: a preliminary study
No full textAir-dried and sterilized amnion has been widely used as a dressing to treat burn and partial thickness wounds. Sterilisation at the standard dose of 25 kGy was reported to cause changes in the morphological structure as observed under the scanning electron microscope. This study aimed to quantify the changes in the ultrastructure of the air-dried amnion after gamma-irradiated at several doses by using atomic force microscope. Human placentae were retrieved from mothers who had undergone cesarean elective surgery. Amnion separated from chorion was processed and air-dried for 16 h. It was cut into 10 × 10 mm, individually packed and exposed to gamma irradiation at 5, 15, 25 and 35 kGy. Changes in the ultrastructural images of the amnion were quantified in term of diameter of the epithelial cells, size of the intercellular gap and membrane surface roughness. The longest diameter of the amnion cells reduced significantly after radiation (p < 0.01) however the effect was not dose dependent. No significant changes in the shortest diameter after radiation, except at 35 kGy which decreased significantly when compared to 5 kGy (p < 0.01). The size of the irradiated air-dried amnion cells reduced in the same direction without affecting the gross ultrastructure. At 15 kGy the intercellular gap decreased significantly (p < 0.01) with Ra and Rq, values reflecting surface roughness, were significantly the highest (p < 0.01). Changes in the ultrastructure quantified by using atomic force microscope could complement results from other microscopic techniques
The impact of a reduction in fluoride concentration in the Malaysian water supply on the prevalence of fluorosis and dental caries
No full textObjective: To assess the prevalence and severity of dental fluorosis and caries among Malaysian children following the reduction in fluoride concentration from 0.7 to 0.5 parts per million (ppm) in the public water supply. Methods: This study involved lifelong residents aged 9- and 12-year-olds in fluoridated and nonfluoridated areas in Malaysia (n = 1155). In the fluoridated area, children aged 12 years and 9 years were exposed to 0.7 and 0.5 ppm, respectively, at the times when maxillary central incisors developed. Standardized photographs of maxillary central incisors were blind scored for fluorosis using Dean's criteria. Dental caries was examined using ICDAS-II criteria. Results: The prevalence of fluorosis (Dean's score ≥ 2) among children in the fluoridated area (35.7%, 95% CI: 31.9%-39.6%) was significantly higher (P < 0.001) than children in the nonfluoridated area (5.5%, 95% CI: 3.6%-7.4%). Of those in the fluoridated area, the prevalence of fluorosis decreased from 38.4% (95% CI: 33.1%-44.3%) for 12-year-olds to 31.9% (95% CI: 27.6%-38.2%) for 9-year-olds, although this difference was not statistically significant (P = 0.139). The mean caries experience in the permanent dentition was significantly lower in the fluoridated area than in the nonfluoridated area for both age groups (P < 0.05). In the multivariate models, the difference in the differences of caries experience between fluoridated and nonfluoridated areas remained statistically significant. This suggests that caries-preventive effect is still maintained at 0.5 ppm. Conclusion: Findings indicate that the change in fluoride level from 0.7 to 0.5 ppm has reduced fluorosis and maintains a caries-preventive effect. Although there is a reduction in fluorosis prevalence, the difference was not statistically significant
1,3-oxazepine compounds derived from azomethine: Synthesis, characterization and antibacterial evaluation
No full textTwo azomethines, namely 2-methoxy-4-phenyliminomethyl-phenol (1) and 4-[(2,4-dinitro-phenyl)-hydrazonomethyl]-2-methoxy-phenol (2) were prepared between the reaction of vanillin with aniline and 2,4-dinitrophenylhydrazine, respectively. Subsequently, these two azomethines were reacted via direct cyclic addition with maleic anhydride, phthalic anhydride and succinic anhydride, respectively, yielded a series of new 1,3-oxazepines (3-8). All the synthesized compounds were characterized on the basis of FT-IR, NMR, MS and elemental analysis (CHN). Disk diffusion and 96-well plate assay methods were employed for zone of inhibition and minimum inhibitory concentration determination respectively to investigate the antibacterial activities. Our studies showed that compound 5 showed promising antibacterial activities with zone of inhibition 24.7 mm against S. aureus, AI value 77.2 % compare to standard ciprofloxacin and MIC was 31.25 μg/mL
Biohydrogen Production by Antarctic Psychrotolerant Klebsiella sp. ABZ11
No full textLower temperature biohydrogen production has always been attractive, due to the lower energy requirements. However, the slow metabolic rate of psychrotolerant biohydrogen-producing bacteria is a common problem that affects their biohydrogen yield. This study reports on the improved substrate synthesis and biohydrogen productivity by the psychrotolerant Klebsiella sp. strain ABZ11, isolated from Antarctic seawater sample. The isolate was screened for biohydrogen production at 30°C, under facultative anaerobic condition. The isolate is able to ferment glucose, fructose and sucrose with biohydrogen production rate and yield of 0.8 mol/l/h and 3.8 mol/g, respectively at 10 g/l glucose concentration. It also showed 74% carbohydrate uptake and 95% oxygen uptake ability, and a wide growth temperature range with optimum at 37°C. Klebsiella sp. ABZ11 has a short biohydrogen production lag phase, fast substrate uptake and is able to tolerate the presence of oxygen in the culture medium. Thus, the isolate has a potential to be used for lower temperature biohydrogen production process
Effects of Stigeoclonium nanum , a freshwater periphytic microalga on water quality in a small-scale recirculating aquaculture system
No full textRecirculating aquaculture systems (RAS) are becoming important for aquaculture due to land and water supply limitations and due to their low environmental impact. Bacteria are important in RAS as their role in nutrient recycling has been the main mechanism for waste removal in these systems. Besides bacteria, the presence of microalgae can benefit the water quality through the absorption of inorganic nitrogen (ammonium and nitrate) and phosphorus from the water. However, reports on the inclusion of microalgae in RAS are very scarce. The objective of this study was to determine the effect of microalgae on water quality (total ammonia nitrogen, nitrite, nitrate and phosphate) and bacterial composition in a freshwater small-scale RAS. A periphytic microalga, Stigeoclonium nanum, was used in this study. A rapid fingerprint analysis, denaturing gradient gel electrophoresis (DGGE), was used to determine the bacterial community composition in the water. The results showed that ammonia concentrations were not significantly different (p > 0.05) between RAS with microalgae (RAS+A) and RAS without microalgae (RAS-A). However, nitrite, nitrate and phosphate were significantly lower in the RAS+A than the RAS-A (p 0.05); however, the bacterial composition between the treatments was significantly different (p < 0.05)
Development of anti-corrosion coatings using the disposable waste material
No full textPurpose: The purpose of this study is to develop anti-corrosion coating systems using disposable waste materials. The dissolved polyethylene terephthalate (PET) has been blended with epoxy resin and stoichiometrically cured with a polyamide resin. Design/methodology/approach: Glycolysis process was found to be the most optimum candidate to dissolve PET. The developed coating systems were characterized by Fourier transform infrared spectroscopy for confirmation of the molecular bonding structures. The mechanical properties were characterized by performing pull-off test and cross hatch test for mechanical properties on the coated panel. Also, the glossiness test was used by reflecting light on the coated surface. The corrosion protection performance of the coated mild steel panels was examined using electrochemical impedance spectroscopy. Furthermore, the wettability of the developed coating systems was evaluated by using water contact angle technique. Findings: It was observed that the coating system which contains 10 per cent of dissolved PET (S2) showed the highest adhesion and corrosion protection properties. Originality/value: Recyclable PET bottles have outstanding chemical properties, adhesion properties, low cost, low permeability to gases and solvents making it suitable as a coating with superior barrier properties
Building Solidarity through Interruption in Face-to-Face Interaction amongst Iranian Men
No full textThis paper investigates interruptions among upper middle-class Iranian men and the way they strategize and manipulate turns in face-to-face interaction. The recordings of informal conversations of these well acquainted men were transcribed and Beattie’s Interruption Model (1981) was adapted and applied as the framework of analysis. This study employed qualitative research design whereby natural-occurring conversation of participants from 15 participants from five groups, with each group comprising three participants, was recorded in the living room of one of the participants. The recorded conversations were transcribed according to an adapted version of Jefferson’s (1979) transcription convention and were qualitatively analysed. The transcribed data were analysed using Beattie’s interruption model (1981) and conversation analysis (CA) to examine the utterances and occurrences of interruptions based on turns being successful and complete at the time of interruptions. The findings of this study suggest that Iranian males interrupt each other cooperatively in order to show their support and solidarity. Although interruptions provide an opportunity for the interlocutors to dominate the interaction, there were no instances of dominance or any traces of intrusive behavior. In fact, the strategic use of interruptions denotes a collective effort to create in-group power that emphasizes solidarity amongst men in this study. This paper yields findings that go against stereotypical characteristics of men who exert power in their interactions. Such findings can be the result of the moderated patriarchal norms in Iranian society, which may have implications for studies on men’s interactional attitudes