Adolescent acne: prevalence, risk factors and quality of life assessment

Akne pripadaju grupi od osam najčešćih bolesti u svetu a jedna su od tri najzastupljenijih kožnih bolesti. Po pravilu se prvi put javljaju u adolescenciji kod oba pola. Procenjena prevalencija adolescentnih akni varira od 41,7% do 94,9%. Rano prepoznavanje i lečenje akni je od ogromnog značaja jer može doprineti sprečavanju emotivnih i psihičkih poremećaja kod obolelih. Najvažniji faktori za pojavu akni su pozitivna porodična anamneza i hiperseboreja kože. Oprečni stavovi su i u domenu uticaja stresa, pušenja, nekvalitetnog sna i drugih navika, a intenzivno se proučava uticaj ekspozoma kao sveukupnog spoljnog štetnog dejstva na akne. Uticaj objektivno i subjektivno procenjene težine kliničke slike akni na umanjenje kvaliteta života je najčešće predmet populacionih istraživanja. Retke su studije koja se bave identifikovanjem faktora koji utiču na lošiji kvalitet života adolescenata sa aknama. Ciljevi. (1) Određivanje prevalencije različitih kliničkih oblika akni kod srednjoškolaca u Beogradu. (2) Utvrđivanje faktora rizika za nastanak akni kod adolescenata. (3) Procena kvaliteta života adolescenata sa aknama i identifikacija faktora koji doprinose lošijem kvalitetu života kod adolescenata sa aknama. (4) Analiza stavova adolescenata o prirodi bolesti, uzrocima nastanka, faktorima koji pogoršavaju bolest, kao i o mogućnostima lečenja. Metod. Sprovedena je studija preseka na stratifikovanom reprezentativnom uzorku adolescenata, učenika srednjih škola u Beogradu, tokom 3 konsekutivna meseca, od decembra 2012. do februara 2013. godine. Škole su odabrane metodom stratifikovanog slučajnog izbora. U cilju obezbeđivanja maksimalne participacije ispitanika, svi dostupni učenici, njih 2833, su bili usmeno obavešteni o vrsti i načinu istraživanja od strane anketara, a učestvovanje u istraživanju je bilo na dobrovoljnoj bazi. Podaci su prikupljeni anketom, a klinički pregled lica je obezbeđen od strane istovetnog anketara-dermatologa za sve učenike. Upitnik se sastojao iz nekoliko osnovnih delova: (1) osnovni demografski podaci , (2) podaci o aknama, (3) podaci o terapiji, (4) podaci o navikama (5) podaci o stavovima i znanju vezanom za akne. U cilju procene subjektivne percepcije stresa upotrebljena je skala percipiranog stresa - PSS (engl. Perceived stress scale). Kvalitet života je ispitivan upotrebom Kardifovog indeksa nesposobnosti u vezi akni (engl. Cardiff Acne Disability Index- CADI), a kvalitet života povezan sa zdravljem SF-36 anketom...and the third most common skin disease. The peak incidence is in adolescence in both gender, the prevalence varies between 41,7% do 94,9%. Considering the great impact of acne on emotional and mental health, the early diagnosis and treatment is essential in order to prevent further complications. The strongest risk factors for acne development are family history of acne and hyperseborrhoea. Conflicting results also refer to effects of stress, tobacco, quality of sleep and other personal habits on acne; the exposome and acne relation is currently under thorough investigation. The influence of objective and subjective acne severity on quality of life impairment is usually analyzed in cross-sectional studies. Still, the evaluation of specific predictive factors of acne disability is rarely performed. Objectives. (1) Prevalence of acne and acne severity grades among schoolchildren aged 14-18 years in Belgrade (2) Assessment of acneassociated risk factors (3) Analysis of quality of life in acne pupils and assessment of predictive factors of its impairment (4) Knowledge, beliefs and perceptions about acne in schoolchildren, including treatment seeking behavior. Method. We conducted cross-sectional study on representative sample of adolescents, high-school children in Belgrade, during 3 consecutive months (Dec 2012. until Feb 2013.). Schools were randomly selected. For maximal participation, the purpose of investigation was explained to 2833 available pupils, and their participation was voluntary. Collection of data was obtained through questionnaires, and the objective acne assessment was provided by single dermatologist-investigator for all participants. The questions were grouped in several parts:(1) basic demographic data, (2) information about acne (3) acne therapy, (4) data on personal behavior (5) knowledge about acne. Subjective assessment of perceived stress was measured using perceived stress scale (PSS). Disability due to acne was assessed with Cardif Acne Disabilty Index (CADI), and SF-36 generic questionnaire was used to assess the health related quality of life..

Synthesis and characterization of ceramic composite materials based on silicon-carbide and cordierite

Predmet ove doktorske disertacije je sinteza i karakterizacija kompozitnih keramičkih materijala na bazi silicijum-karbida i kordijerita. Silicijum-karbid, SiC, je kovalentno jedinjenje male gustine, velike tvrdoće, odlične termičke stabilnosti, dobre toplotne provodljivosti, dobre otpornosti prema termošoku. Ovakva svojstva omogućavaju njegovu brojnu primenu u raznim oblastima. Zbog kovalentne prirode veze, dobijanje guste SiC keramike je nemoguće bez dodatka aditiva. Dosadašnja ispitivanja su pokazala da se dodatkom smese oksida, kao aditiva, dobija gusta SiC keramika na temperaturama ispod 2100°C. Kordijerit, 2MgO 2Al2O3 5SiO2, poseduje odličnu termičku stabilnost, nizak koeficijent toplotnog širenja i dobru otpornost prema termošoku. U ovom radu kordijerit je dobijen iz dva izvora: iz spinela, MgAl2O4, i iz Mg-izmenjenog zeolita LTA a zatim je uz dodatak silicijum-karbida korišćen za sintezu kompozitnih materijala. Kompozitni materijali dobijeni su mehaničkim mešanjem SiC sa 30 i 50 mas.% kordijerita, dobijeno je četiri vrste kompozita. Posebna pažnja posvećena je proučavanju procesa sinterovanja u cilju dobijanja keramike sa poboljšanim fizičko-hemijskim svojstvima variranjem parametara sastav-temperaturapritisak. Praćen je uticaj sadržaja dodatog kordijerita na termostabilnost SiC/kordijeritnog kompozitnog materijala pošto poznavanje otpornosti vatrostalnih materijala prema termošoku određuje njihovu primenu. Dodatak grafita omogućio je formiranje pora tokom sinterovanja. Sadržaj dodatog grafita značajno utiče na poroznost i čvrstoću kompozitnog materijala pa je proučavan uticaj poroznosti na termostabilnost kompozitne keramike. U okviru istraživanja korišćene su nedestruktivnih metode karakterizacije: ultrazvučne metode za određivanje dinamičkog Jungovog modula elastičnosti i čvstoće tokom ispitivanja termošoka, kao i primena alata za analizu slike, Image Pro Plus program, radi određivanja stepena oštećenja uzoraka pre i u toku ispitivanja termostabilnosti. Uspostavljene su zavisnosti i predloženi modeli između izmerenih brzina prostiranja ultrazvučnih talasa, Jungovog modula elastičnosti, kao i stepena oštećenja uzoraka sa brojem ciklusa termošoka. Ustanovljeno je veoma dobro slaganje između rezultata predloženih modela posmatranih veličina sa brojem ciklusa termošoka. Ovakav pristup je doveo do razvoja modela za predviđanje smanjenja čvrstoće kompozitnih materijala usled termošoka na osnovu promena brzine prostiranja ultrazvučnih talasa kroz kompozitne materijale, kao i stepena oštećenja površine kompozitnih materijala. Takođe, ovaj pristup je iskorišćen radi razvijanja modela koji određuju kritični broj ciklusa, koje kompozitni materijali izdrže a da ne dođe do razaranja 50 % čeone površine usled izlaganja termošoku, na osnovu promena posmatranih parametara (brzina prostiranja ultrazvuka kroz materijal i stepen oštećenja površine)...The aims of this dissertation are synthesis and characterization of silicon-carbide and cordierite based ceramic composite materials. Silicon-carbide, SiC, is low density covalent compound with high hardness value, excellent thermal stability, high thermal conductivity and good thermal shock resistance. These properties of SiC allow numerous applications in different fields. Covalent bond of SiC precludes formation of high density SiC ceramics without additive. Previous investigations show that the combination of oxide mixture and SiC results in dense SiC ceramics at temperatures up to 2100°C. Cordierite, 2MgO 2Al2O3 5SiO2, has excellent thermal stability, low coefficient of thermal conductivity and good thermal shock resistance. In this dissertation cordierite was synthesized by using two sources: spinel, MgAl2O4, and Mg-exchanged zeolite LTA and then, the mechanical commixtures with SiC powder were prepared with the aim of obtaining four types of composite materials with 30 and 50 wt% of cordierite. Particular attention in this thesis was focused on sintering process. Processing parameters such are composition, temperature, and pressure were changed with the aim of synthesizing ceramics with good physical-chemical properties. Variation of cordierite content in composite materials was applied due to examine his impact on thermal stability of SiC-cordierite composite materials. Graphite, as pore former during sintering, was added to change porosity of SiC-cordierite composite materials. Since addition of graphite has strong influence on porosity and hardness, the influence of graphite additions, 10, 20, and 30 wt%, on thermal stability of SiC-cordierite composite materials was investigated. Nondestructive methods of characterization were applied: ultrasonic pulse velocity technique for determination of dynamic Young modulus of elasticity and strength during the thermal shock investigation as well as tools for image analyses Image pro Plus program for determination of degradation level before and during the thermal shock experiment. Correlations and models between measured ultrasonic velocity, Young modulus of elasticity and degree of degradation were established. Good agreement between the results of suggested models of analyzed parameters with number of thermal shock cycles were obtained. This approach leads to the models for prediction of strength degradation level of composite materials during the thermal shock based on changes of ultrasonic velocity through the composite materials and level of surface degradation. Based on this analysis, model for prediction of critical number of cycles, the number of cycles that composite materials exposed to thermal shock can withstand without surface degradation less than 50 %, was developed..

Malaco temperature reconstructions and numerical simulation of environmental conditions in the southeastern Carpathian Basin during the Last Glacial Maximum

We investigate the glacial climate conditions in the southeastern Carpathian Basin (Vojvodina, Serbia) based on the reconstruction of malacological palaeotemperatures and results from a high‐resolution regional climate simulation. Land snail assemblages from eight loess profiles are used to reconstruct July temperatures during the Last Glacial Maximum (LGM). The malacological reconstructed temperatures are in good agreement with the simulated LGM July temperatures by the Weather Research and Forecast model. Both methods indicate increasing temperatures from the northwestern towards the southeastern parts of the study area. LGM aridity indices calculated based on the regional climate model data suggest more arid conditions in the southeastern parts compared with more humid conditions in the northwestern parts. However, for present‐day conditions, the moisture gradient is reversed, exhibiting more humid (arid) conditions in the southeast (northwest). An explanation for the reversed LGM aridity pattern is provided by an analysis of the prevailing wind directions over the South Banat district (Serbia). The prevailing moist northwesterly winds during summer are not able to compensate for the annual lack of moisture induced by the dry winds from the southeast that are more frequent during the LGM for the other seasons

Phase evolution of Si3N4 with Mg-exchanged zeolite additive

This paper deals with the chemical reactions and phase evolution during pressureless sintering of Si3N4 with Mg-exchanged zeolite as sintering additive. The XRD data show that the first MgO-rich liquid forms at as low as 1250 °C, which as a consequence results in a significant reduction of sintering temperature. At 1300 °C the β−Si3N4 phase had disappeared indicating its dissolution into the liquid phase. At 1500 °C the secondary phase had been completely converted into a glassy phase, however, no phase transformation from α−Si3N4 to β−Si3N4 had taken place. Thus the composition of this material consists of α−Si3N4 embedded in magnesium silicon oxynitride glassy phase.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Synthesis of fibrous SiC from natural precursor

Fibrous magnesio-silicate (mountain leather asbestos) of Serbian origin was used as Si precursor for the synthesis of SiC by carbothermal-reduction process [1, 2]. As a reducing agent, sugar (saccharose) was used. Formation of SiC was confirmed by XRD analysis and optical microscopy images. Results showed that obtained SiC possess fibrous morphology. Due to the experimental procedure MgF2 is also formed, which is known as an excellent additive for sintering of non-oxide ceramics.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Antimicrobial growth promoters in feed - possibilities and necessity

The attention of the scientific and professional communities, as well as of food consumers, has always been directed towards finding adequate nutritional strategies that could improve food production and safety. By using antibiotics as feed additives, farmers gained increased profits based on higher growth rates with better feed conversion and lower costs of therapeutic treatment. The quantities of antibiotics used as growth promoters for farm animals have been increasing constantly, but at the same time, the frequency of bacterial resistance to antibiotics and the presence of antibiotic residues in food have become a global problem. To eliminate or minimize these risks, on 1 January 2006, antibiotics were banned from use as additives in animal nutrition in the European Union. Accordingly, there is interest in developing new nutritional strategies that would support the function of the autochthonous microbiota in the animal gastrointestinal tract to control pathogenic bacteria. Probiotics, prebiotics, phytobiotics and feed enzymes are a new generation of growth promoters and largely achieve their effects by using the physiological mechanisms of animals and/or their intestinal microbiomes, enabling animals to completely fulfil their genetic potential with respect to production properties

Reduction in Pathogenic Biofilms by the Photoactive Composite of Bacterial Cellulose and Nanochitosan Dots under Blue and Green Light

In this study, nanochitosan dots (ChiDs) were synthesized using gamma rays and encapsulated in bacterial cellulose (BC) polymer matrix for antibiofilm potential in photodynamic therapy. The composites were analyzed for structural changes using SEM, AFM, FTIR, XRD, EPR, and porosity measurements. Additionally, ChiD release was assessed. The results showed that the chemical composition remained unaltered, but ChiD agglomerates embedded in BC changed shape (1.5–2.5 µm). Bacterial cellulose fibers became deformed and interconnected, with increased surface roughness and porosity and decreased crystallinity. No singlet oxygen formation was observed, and the total amount of released ChiD was up to 16.10%. Antibiofilm activity was higher under green light, with reductions ranging from 48 to 57% under blue light and 78 to 85% under green light. Methicillin-resistant Staphylococcus aureus was the most sensitive strain. The new photoactive composite hydrogels show promising potential for combating biofilm-related infections

Synthesis, crystal structure and biological activity of copper(II) complex with 4-nitro-3-pyrazolecarboxylic ligand

The reaction of 4-nitro-3-pyrazolecarboxylic acid and Cu(OAc)2⋅H2O in ethanol resulted in a new coordination compound [Cu2(4-nitro-3- -pzc)2(H2O)6]2H2O (4nitro-3pzc = 4-nitro-3-pyrazolecarboxylate). The compound was investigated by means of single-crystal X-ray diffraction and infrared spectroscopy. The biological activity of the complex was also tested. In the crystal structure of [Cu2(4nitro-3-pzc)2(H2O)6]2H2O, the Cu(II) ion is in a distorted [4+2] octahedral coordination due to the Jan–Teller effect. A survey of the Cambridge Structural Database showed that the octahedral coordination geometry is generally rare for pyrazole-bridged Cu(II) complexes. In the case of Cu(II) complexes with the 3-pyrazolecarboxylato ligands, no complexes with a similar octahedral coordination geometry have been reported. Biological research based on determination of the inhibition effect of the commercial fungicide Cabrio top and the newly synthesized complex on Ph. viticola were performed using the phytosanitary method

Reconstructed Malacothermometer July Paleotemperatures from the Last Nine Glacials over the South-Eastern Carpathian Basin (Serbia)

In this study, the compiled malacological record of the two most important loess–palaeosol sequences (LPS) in Serbia was used to reconstruct the Malacothermometer July Paleotemperature (MTJP) of the last nine glacials. The sieved loess samples yielded shells of 11 terrestrial gastropod species that were used to estimate the MTJP. Veliki Surduk (covering the last three glacial cycles) and Stari Slankamen (covering the last fourth to ninth glacial cycle) LPSs previously lacked the malacological investigations. After the sieving, a total of 66,871 shells were found, from which 48,459 shells were used for the estimation of the MTJP. Through the studied period, the reconstructed MTJP was ranging from 14.4 °C to 21.5 °C. The lowest temperature was recorded during the formation of the loess unit L5, equivalent to the Marine Isotope Stage (MIS) 12. The second-coldest summers were occurring during the MIS 16 glacial. Although the warmest glacial was L8 (MIS 20) according to MTJP, these July temperatures might be overestimated due to only two samples from the poorly preserved L8 unit. The malacological material derived from the loess units at Veliki Surduk and Stari Slankamen LPSs showed great potential for July temperature reconstruction, as the comparison with other regional records showed similar climate changes. Further work is necessary to validate the age scale of the oldest samples, and a higher resolution sampling could lead to more detailed July temperature fluctuations, as was shown for the youngest glacial in this study. Likewise, estimating the July temperature using different proxies (e.g., pollen) from the same LPSs could be used to confirm the observed climate trends

ALGORITHM FOR UPTAKE ASSESSMENT IN SMALL LESIONS BASED ON DYNAMIC SCINTIGRAPHY SCANS

The aim of our research was to develop an algorithm for estimation and visualisation of radiopharmaceutical uptake based on time-activity-curve (TAC) analysis in small regions of interest (ROI) in scintigraphic studies. The algorithm is implemented in Labview environment (National Instruments, Texas, Austin) and comprises the following steps: 1) delineation of grid of small ROIs over the examined tissue and corresponding TAC processing; 2) background vs tissue separation; 3) the extraction of all “suspected“ ROIs where TACs are not exponentially descendent; 4) correlation analysis between a TAC corresponding to the suspicious lesion ROI and TACs of neghboring ROIs; 5) the extraction of representative TAC for “suspected“ area by Principal Component Analysis technique; and 6) visual interpretation of radiopharmaceutical distribution in the “suspected“ area. The application of algorithm is presented in data recorded in case of histopathologically proven parathyroid tumors