10 research outputs found
Work related characteristics, work-home and home-work interference and burnout among primary healthcare physicians: A gender perspective in a Serbian context
The influence of surfactant structure on the dyeing of polyamide knitting with acid dyes
The influence of nonionic and anionic surfactants on the dyeing kinetics of polyamide 6 knitting was studied in this work. The influence of surfactants on the dyeing process is presented by determining the kinetic and thermodynamic parameters of dyeing. Nonionic surfactants create unstable polydisperse associates which reduce the concentration of individual ionic forms of dyes in the solution, slowing down the dyeing process, with the dyeing having higher leveling. Interactions were confirmed by measuring the cloud point of nonionic surfactants and they are stronger with more hydrophobic dye and are related to the results of the studied dyeing kinetics. The anionic surfactant as a retarding agent, which behaves like a colorless dye in the studied dyeing system, makes a significant contribution even at concentrations of 0.5 and 1 g/dm3, indicating the conclusion that the surfactant concentration in a dyeing solution should be optimized by previous trials, so that the process would be efficient with high utilization of dye
Effect of agitation rate on the production of antifungal metabolites by Streptomyces hygroscopicus in a lab-scale bioreactor
The application of antifungal compounds produced by microorganisms in the
control of plant diseases caused by phytopathogenic fungi is a promising
alternative to synthetic pesticides. Among phytopathogenic fungi, Alternaria
alternata and Fusarium avenaceum are significant pathogens responsible for
the storage rot of apple fruits. During storage, transport and marketing A.
alternata and F. avenaceum can cause significant losses of apple fruits and
their control is of great importance for the producers and consumers. In the
present study, the effects of agitation rate on the production of antifungal
methabolite( s) by Streptomyces hygroscopicus in a 3-L lab-scale bioreactor
(Biostat® Aplus, Sartorius AG, Germany) against two isolates of A. alternata
and two isolates of F. avenaceum were investigated. The cultivation of S.
hygroscopicus was carried out at 27°C with agitation rates of 100 rpm and
200 rpm during 7 days. The aim was to analyze the bioprocess parameters of
biofungicide production in a medium containing glycerol as a carbon source,
and examine the effect of agitation rate on the production of antifungal
metabolite(s). The in vitro antifungal activity of the produced metabolites
against fungi from the genera Alternaria and Fusarium grown on potato
dextrose agar medium was determined every 24 h using wells technique. In the
experiments conducted in the bioreactor at different stirring speeds, it was
found that the maximum production of antifungal metabolites occurred after 96
hours of cultivation. A higher consumption of nutrients and a larger
inhibition zone diameter was registered in the experiment with an agitation
rate of 200 rpm. [Project of the Serbian Ministry of Education, Science and
Technological Development, Grant no. TR-31002
Parathyroid dual tracer subtraction scintigraphy: small regions method for quantitative assessment of parathyroid adenoma uptake.
OBJECTIVE: The aim was quantitative assessment of parathyroid adenoma (PTA) uptake in dual tracer dynamic scintigraphy.
METHODS: In 78 patients, median age 58 (19-80) years, surgically treated for primary hyperparathyroidism (PHPT), with parathyroid hormone median 125 (70-658) pg/ml, we performed preoperative parathyroid scintigraphy, following EANM guidelines of subtraction and double-phase protocol (2009) using two tracers: Tc-99m pertechnetate and Tc-99m MIBI. In addition to standard subtraction processing and visual interpretation of delayed MIBI planar images of neck and mediastinum in oblique sections (positions according to ultrasound PTA localisation), we developed Submarine processing software that enables selecting custom regions grid sizes ≥6 mm (as this solution was not present in commercial software) to follow time activity curve changes in thyroid tissue and PTA. Histopathology in 53/78 patients revealed PHPT and in 25/78 patients thyroid nodular disease only, and thyroid malignancy occurred in total of 15/78 (19 %) patients. PHPT group included 44 solitary PTA, 8 patients with hyperplasia and one parathyroid carcinoma. The median macroscopic volume of PTA was 717.5 (15-6125) mm(3). Concomitant PHPT and thyroid nodular disease occurred in 24/53 patients and among them 8 patients had thyroid malignancies.
RESULTS: PTA showed typical pattern of late peak on time activity curves characterized by median start time on 15 (10-25) min, the peak amplitude mean 19 (±5) % above thyroid declining washout curve, and duration of peak 6 (4-10) min, allowing PTA to "emerge" like submarine, independent from thyroid tissue and lesions. The ratio of PTA-to-normal thyroid uptake at peak maximum was 1.35 (±0.21). The thyroid TACs results of normal 29/78 (37 %) patients, benign nodular 34/78 (44 %) patients, and malignancy in 15 (19 %) patients were all presented by declining exponential curves. The slope analysis of TACs in normal thyroid tissue, thyroid benign and malignant lesions (linear fitted logarithm of TAC) showed no difference (the same negative slope: -0.04). Submarine processing was sensitive in detection of small lesions, in hyperplasia, and concomitant thyroid nodular disease.
CONCLUSIONS: The novel Submarine processing confirmed specific PHPT pattern and was effective in the group with potential pitfalls of standard interpretation, increasing sensitivity and specificity of standard processing subtraction algorithm. Prolonged MIBI accumulation was present in malignant as well as benign thyroid nodules with identical TAC slope
Optimization of the flux values in multichannel ceramic membrane microfiltration of Baker`s yeast suspension
The objective of this work was to estimate the effects of the operating
parameters on the baker's yeast microfiltration through multichannel ceramic
membrane. The selected parameters were transmembrane pressure, suspension
feed flow, and initial suspension concentration. In order to investigate the
influence and interaction effects of these parameters on the microfiltration
operation, two responses have been chosen: average permeate flux and flux
decline. The Box-Behnken experimental design and response surface methodology
was used for result processing and process optimization. According to the
obtained results, the most important parameter influencing permeate flux
during microfiltration is the initial suspension concentration. The maximum
average flux value was achieved at an initial concentration of 0.1 g/L,
pressure around 1.25 bars and a flow rate at 16 L/h. [Projekat Ministarstva
nauke Republike Srbije, br. TR 31002