12 research outputs found
TIME SERIES ANALYSIS: FORECASTING SALES PERIODS IN WHOLESALE SYSTEMS
The main goal of time series analysis is explaining the correlation and the main features of the data in chronological order by using appropriate statistical models. It is being used in various aspects of life and work, as well as in forecasting future product demands, service demands, etc. The most common type of time series data is the one whose observations are taken in equally distributed time intervals (daily, weekly, monthly, etc.). However, in this paper, we analyze a different kind of time series which represents product purchase moments. Thus, since there are not any regular observation periods, this irregular time series must be transformed in some way before traditional methods of analysis can be applied. After the data transformation is complete, the next step is modeling the nonstationary time series using commonly known models such as ARIMA and PNBD, which have been chosen for their fairly easy and successful forecasting processes. The goal of this analysis is timely product advertising to a customer in order to increase sales.Unlike some other models that consider the relationship between two or more different phenomena, time series models, including ARIMA, Pareto/NBD and Poisson models, examine the impact of historical values of a single phenomenon on its present and future value. This approach enables the study of the behavior of a given phenomenon over time and produces good results, especially if a large amount of historical data is available
Ecological status assessment of the Samokovska river: 2018 case study
The Samokovska River, as the most important watercourse of the Kopaonik National Park, has been poorly investigated from algological and water quality aspects. This river is not covered by the monitoring program of the Serbian Environmental Protection Agency routine. Our research performed in October 2018 aimed to present an algal diversity, ecological status assessment, and negative anthropogenic impacts threatening this river. For ecological status assessment purposes, the diatom indices phytobenthos and physico-chemical parameters of water were used. The typology and the problem of reliable assessing of the ecological status were also discussed on the example of the Samokovska River
Suplementacija magnezijuma i status gvožđa kod studentkinja - studija intervencije
Abstract Background: Literature data indicate the benefit of magnesium (Mg) supplementation. The aim of this study was to examine the effect of short-term Mg supplementation on iron status in healthy female participants. Methods: One hundred healthy female students of the University of Belgrade - Faculty of Pharmacy participated the study during eleven intervention days. Students ingested Mg preparations with the same dose of the active substance. The analysis included the measurement of serum iron, unsaturated iron binding capacity (UIBC), total iron binding capacity (TIBC), total Mg (tMg), ionized Mg (iMg), complete blood count, met-, carboxy- and oxy-haemoglobin (metHgb, COHgb, O2Hgb). Transferrin concentrations and percentage of transferrin saturation (SAT) were calculated manually. The association among the analyzed biochemical parameters was examined using polynomial regression. A principal component analysis (PCA) was used for the evaluation of interdependence between the analyzed parameters. Results: A statistically significant trend for change in O2Hgb (%) by tertiles of iMg concentrations was found (P = 0.029). Serum tMg reached significant positive correlation with the SAT at concentration levels greater than 0.9 mmol/L, after 11 days of intervention (R2=0.116). Ionized Mg in a concentration higher than 0.6 mmol/L is positively correlated with SAT and serum Fe (R2=0.214; 0.199, respectively). PCA revealed variability of 64.7% for two axes after 11 days. Conclusions: Mg supplementation leads to an improvement in the certain iron status parameters even in individuals with optimal levels of these indices. However, caution should be exercised when supplementing Mg, and laboratory monitoring of the interaction is required.Uvod: Literaturni podaci ukazuju na benefit suplementacije magnezijumom (Mg). Cilj ove studije bio je da se ispita uticaj kratkotrajne suplementacije Mg na status gvožđa kod zdravih žena. Metode: Sto zdravih studentkinja Univerzitet u Beogradu - Farmaceutskog fakulteta je učestvovalo u istraživanju tokom jedanaest dana intervencije. Studenti su uzimali preparate Mg sa istom dozom aktivne supstance. U serumu je određivano gvožđe, nezasićen kapacitet vezivanja gvožđa (UIBC), ukupan kapacitet vezivanja gvožđa (TIBC), ukupan Mg (tMg), jonizovni Mg (iMg), kompletna krvna slika, met-, karboksiioksihemoglobin (metHgb, COHgb, O2Hgb). Transferin i saturacija transferina (SAT) su izračunati ručno. Povezanost analiziranih biohemijskih parametara je ispitana pomoću polinomalne regresije. Za procenu međuzavisnosti između analiziranih parametara korišćena je analiza glavnih komponenti (PCA). Rezultati: Utvrđen je statistički značajan trend promene O2Hgb (%) po tertilima koncentracija iMg (P = 0,029). Ukupan Mg je dostigao značajnu pozitivnu korelaciju sa SAT pri koncentracijama većim od 0,9 mmol/L, nakon 11 dana intervencije (R2 = 0,116). Jonizovani Mg u koncentraciji većoj od 0,6 mmol/L pozitivno korelira sa SAT i gvožđem (R2 = 0,214; 0,199, redom). PCA analizom je pokazana varijabilnost od 64,7% za dve ose nakon 11 dana. Zaključak: Suplementacija Mg dovodi do poboljšanja određenih parametara statusa gvožđa čak i kod pojedinaca sa optimalnim nivoima ovih parametara. Međutim treba biti oprezan pri suplementaciji Mg, a dodatno je neophodno i laboratorijsko praćenje ovih interakcija
Erosion control and protection from torrential floods in Serbia-spatial aspects
Torrential floods represent the most frequent phenomenon within the category
of “natural risks” in Serbia. The representative examples are the torrential
floods on the experimental watersheds of the rivers Manastirica (June 1996)
and Kamišna (May 2007). Hystorical maximal discharges (Qmaxh) were
reconstructed by use of ″hydraulics flood traces″ method. Computations of
maximal discharges (Qmaxc), under hydrological conditions after the
restoration of the watersheds, were performed by use of a synthetic unit
hydrograph theory and Soil Conservation Service methodology. Area sediment
yields and intensity of erosion processes were estimated on the basis of the
“Erosion Potential Method”. The actual state of erosion processes is
represented by the coefficients of erosion Z=0.475 (Manastirica) and Z=0.470
(Kamišna). Restoration works have been planned with a view to decreasing
yields of erosive material, increasing water infiltration capacity and
reducing flood runoff. The planned state of erosion processes is represented
by the coefficients of erosion Z=0.343 (Manastirica) and Z=0.385 (Kamišna).
The effects of hydrological changes were estimated by the comparison of
historical maximal discharges and computed maximal discharges (under the
conditions after the planned restoration). The realisation of restoration
works will help decrease annual yields of erosive material from Wа=24357 m3
to Wа=16198.0 m3 (Manastirica) and from Wа=19974 m3 to Wа=14434 m3 (Kamišna).
The values of historical maximal discharges (QmaxhMan=154.9 m3•s-1;
QmaxhKam=76.3 m3•s-1) were significantly decreased after the restoration
(QmaxcMan=84.5 m3 •s-1; QmaxcKam=43.7 m3•s-1), indicating the improvement of
hydrological conditions, as a direct consequence of erosion and torrent
control works. Integrated management involves biotechnical works on the
watershed, technical works on the hydrographic network within a precisely
defined administrative and spatial framework in order to achieve maximum
security for people and their property and to meet other requirements such
as: environmental protection, sustainable soil usage, drinking water supply,
rural development, biodiversity sustaining, etc. The lowest and the most
effective level is attained through PAERs (Plans for announcement of erosive
regions) and PPTFs (Plans for protection from torrential floods), with HZs
(Hazard zones) and TAs (Threatened areas) mapping on the basis of spatial
analysis of important factors in torrential floods formation. Solutions
defined through PAERs and PPTFs must be integrated into Spatial Plans at
local and regional levels
Erosion control and protection from torrential floods in Serbia-spatial aspects
Torrential floods represent the most frequent phenomenon within the category of 'natural risks' in Serbia. The representative examples are the torrential floods on the experimental watersheds of the rivers Manastirica (June 1996) and Kamišna (May 2007). Hystorical maximal discharges (Qmaxh) were reconstructed by use of 'hydraulics flood traces' method. Computations of maximal discharges (Qmaxc), under hydrological conditions after the restoration of the watersheds, were performed by use of a synthetic unit hydrograph theory and Soil Conservation Service methodology. Area sediment yields and intensity of erosion processes were estimated on the basis of the 'Erosion Potential Method'. The actual state of erosion processes is represented by the coefficients of erosion Z=0.475 (Manastirica) and Z=0.470 (Kamišna). Restoration works have been planned with a view to decreasing yields of erosive material, increasing water infiltration capacity and reducing flood runoff. The planned state of erosion processes is represented by the coefficients of erosion Z=0.343 (Manastirica) and Z=0.385 (Kamišna). The effects of hydrological changes were estimated by the comparison of historical maximal discharges and computed maximal discharges (under the conditions after the planned restoration). The realisation of restoration works will help decrease annual yields of erosive material from Wa=24357 m3 to Wa=16198.0 m3 (Manastirica) and from Wa=19974 m3 to Wa=14434 m3 (Kamišna). The values of historical maximal discharges (QmaxhMan=154.9 m3·s-1; QmaxhKam=76.3 m3·s-1) were significantly decreased after the restoration (QmaxcMan=84.5 m3 ·s-1; QmaxcKam=43.7 m3·s-1), indicating the improvement of hydrological conditions, as a direct consequence of erosion and torrent control works. Integrated management involves biotechnical works on the watershed, technical works on the hydrographic network within a precisely defined administrative and spatial framework in order to achieve maximum security for people and their property and to meet other requirements such as: environmental protection, sustainable soil usage, drinking water supply, rural development, biodiversity sustaining, etc. The lowest and the most effective level is attained through PAERs (Plans for announcement of erosive regions) and PPTFs (Plans for protection from torrential floods), with HZs (Hazard zones) and TAs (Threatened areas) mapping on the basis of spatial analysis of important factors in torrential floods formation. Solutions defined through PAERs and PPTFs must be integrated into Spatial Plans at local and regional levels
O,O'-diethyl-(S,S)-ethylenediamine-N,N'-di-2-(3-cyclohexyl)propanoate dihydrochloride enhances influx of effective NK and NKT cells in murine breast cancer
Background/Aim. O,O'-diethyl-(S,S)-ethylenediamineN,N'-di-2-(3-cyclohexyl)propanoate dihydrochloride (DE-EDCP) has been found to possess promising cytotoxic activity against various tumor cell lines. Also, DE-EDCP reduces tumor progression by several mechanisms such as triggering tumor cell death and inhibition of cell proliferation. The aim of present study was to further evaluate antitumor activity of DE-EDCP by investigating effects on migratory potential of tumor cells and anti-tumor immune response. Methods. Migratory potential of DE-EDCP was evaluated by scratch wound assay. Female BALB/c mice were inoculated with 4T1 breast cancer cells and treatment with DE-EDCP started five days following orthotopic tumor implantation. The frequency and phenotype of tumor-infiltrating natural killer (NK) and natural killer T (NKT) cells were analyzed by flow cytometry. Results. DE-EDCP inhibited migratory potential of highly metastatic 4T1 cells. DE-EDCP facilitated accumulation of CD3+CD49+ NKT cells and CD3-CD49+ NK cells in tumor microenvironment. DE-EDCP treatment led to significant decrement of tumor infiltrating anergic NKT cells expressing cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), killer cell lectin like receptor G1 (KLRG-1) and programmed cell death protein-1 (PD-1). Mice given DE-EDCP had significantly increased percentages of tumoricidal fas ligand (FasL) positive NK cells. Conclusion. DE-EDCP inhibits murine breast cancer progression through direct effects on tumor cells and by facilitating anti-tumor immunity. DE-EDCP enhances accumulation, promotes tumoricidal phenotype and maintenances responsiveness of NK and NKT cells in 4T1 murine breast cancer
Suplementacija magnezijuma i status gvožđa kod studentkinja - studija intervencije
Background: Literature data indicate the benefit of magne-
sium (Mg) supplementation. The aim of this study was to
examine the effect of short-term Mg supplementation on
iron status in healthy female participants.
Methods: One hundred healthy female students of the
University of Belgrade - Faculty of Pharmacy participated the
study during eleven intervention days. Students ingested Mg
preparations with the same dose of the active substance. The
analysis included the measurement of serum iron, unsaturat-
ed iron binding capacity (UIBC), total iron binding capacity
(TIBC), total Mg (tMg), ionized Mg (iMg), complete blood
count, met-, carboxy- and oxy-haemoglobin (metHgb,
COHgb, O2Hgb). Transferrin concentrations and percentage
of transferrin saturation (SAT) were calculated manually. The
association among the analyzed biochemical parameters was
examined using polynomial regression. A principal compo-
nent analysis (PCA) was used for the evaluation of interde-
pendence between the analyzed parameters.
Results: A statistically significant trend for change in O2Hgb
(%) by tertiles of iMg concentrations was found (P = 0.029).
Serum tMg reached significant positive correlation with the
SAT at concentration levels greater than 0.9 mmol/L, after
11 days of intervention (R2=0.116). Ionized Mg in a con-
centration higher than 0.6 mmol/L is positively correlated
with SAT and serum Fe (R2=0.214; 0.199, respectively).
PCA revealed variability of 64.7% for two axes after 11 days.
Conclusions: Mg supplementation leads to an improvement
in the certain iron status parameters even in individuals with
optimal levels of these indices. However, caution should be
exercised when supplementing Mg, and laboratory monitor-
ing of the interaction is required.Uvod: Literaturni podaci ukazuju na benefit suplementacije magnezijumom (Mg). Cilj ove studije bio je da se ispita uticaj kratkotrajne suplementacije Mg na status gvožđa kod zdravih žena. Metode: Sto zdravih studentkinja Univerzitet u Beogradu - Farmaceutskog fakulteta je učestvovalo u istraživanju tokom jedanaest dana intervencije. Studenti su uzimali preparate Mg sa istom dozom aktivne supstance. U serumu je određivano gvožđe, nezasićen kapacitet vezivanja gvožđa (UIBC), ukupan kapacitet vezivanja gvožđa (TIBC), ukupan Mg (tMg), jonizovni Mg (iMg), kompletna krvna slika, met-, karboksiioksihemoglobin (metHgb, COHgb, O2Hgb). Transferin i saturacija transferina (SAT) su izračunati ručno. Povezanost analiziranih biohemijskih parametara je ispitana pomoću polinomalne regresije. Za procenu međuzavisnosti između analiziranih parametara korišćena je analiza glavnih komponenti (PCA). Rezultati: Utvrđen je statistički značajan trend promene O2Hgb (%) po tertilima koncentracija iMg (P = 0,029). Ukupan Mg je dostigao značajnu pozitivnu korelaciju sa SAT pri koncentracijama većim od 0,9 mmol/L, nakon 11 dana intervencije (R2 = 0,116). Jonizovani Mg u koncentraciji većoj od 0,6 mmol/L pozitivno korelira sa SAT i gvožđem (R2 = 0,214; 0,199, redom). PCA analizom je pokazana varijabilnost od 64,7% za dve ose nakon 11 dana. Zaključak: Suplementacija Mg dovodi do poboljšanja određenih parametara statusa gvožđa čak i kod pojedinaca sa optimalnim nivoima ovih parametara. Međutim treba biti oprezan pri suplementaciji Mg, a dodatno je neophodno i laboratorijsko praćenje ovih interakcija
IMMOBILIZATION OF TYRAMINE-HRP ONTO TYRAMIDECARBOXYMETHYL CELLULOSE MATRIX FOR WASTEWATER TREATMENT
Horseradish peroxidase (HRP, E.C. 1.11.1.7) catalyzes oxidation of aqueous aromatic compounds
using hydrogen peroxide. Enzymatic treatment methods for phenol removal from wastewaters has
become an efficient and environmentally friendly alternative for the traditional methods.
Carboxymethyl cellulose (CMC) derivative with tyramine attached via amide bond to carboxyl groups
has been chosen as carrier for immobilization. In effort to overcome the main disadvantage of
entrapment immobilization method, loss of enzyme activity due to washing out from the carrier, HRP
was modified in a reductive amination reaction and tyramine was bound to the enzyme.
Immobilization of tyramine-HRP onto tyramide-carboxymethyl cellulose carrier was carried in an
emulsion polymerization reaction that produced carboxymethyl cellulose microbeads. The highest
specific activity of the obtained biocatalyst was 0.227 U/ml and after 48h of storage 0.197 U/ml.
Immobilized tyramine-HRP retained 87% of activity after 48 h. Immobilized HRP is a suitable
candidate for wastewater treatment
STRUCTURAL CHARACTERISATION AND ORIENTATION OF CELL WALL POLYMERS IN MAIZE LEAVES
Cell wall can be considered as a nano-composite in which cellulose, lignin and hemicelluloses are
interconnected in a specific manner. Mechanical and physical propreties of plant fibres are dependent
on the orientation of constituent polymers (cellulose, hemicellulose, lignin). Fourier transform
infrared (FTIR) microscopy was used to examine the orientation of the main plant polymers in
transversal and longitudinal direction of the isolated cell wall of the maize leaves. Polarised FTIR
measurements indicated an anisotropy, i.e. orientation of the cellulose microfibrils that was more or
less parallel to the longitudinal axis of the cell wall. Xylan has parallel orientation with regard to the
orientation of cellulose, as well as lignin
Wastewater treatment by aminated peroxidase in alginate hydrogel
Phenols are highly toxic organic compounds found in wastewater due to various industries’ pollution. Its removal is of great importance for human and animal health. Enzymatic wastewater treatment has several advantages over traditional methods. Enzyme immobilization onto solid carriers enables its reusability and lowers the cost of treatment. In this work, immobilized horseradish peroxidase on chemically modified alginate hydrogel was tested for phenol removal. The reusability of the tested immobilizate was monitored in repeated cycles. After five consecutive cycles, the remaining activity of the immobilized enzyme was 54%. The obtained result shows the potential for using this immobilizate for wastewater treatment