123 research outputs found
The reduction of nitroaromatic compaunds on the platinum electrode
The reduction of 2,4,6-trinitrotoluene (TNT),as an example of nitroaromatic compounds with three nitro groups, was investigated by cyclic voltammetry on a platinum electrode in aqueous sodium chloride solutions with acetonitrile. The obtained cyclic voltammograms showed three well-pronounced reduction peaks in the potential range of ā0.43 to ā0.8 V (vs. Ag/AgCl reference electrode). The potentials of the peaks were dependant on the potential scan rate as well as on the TNT concentration, indicating the irreversibility of the reduction process. A calibration curve as a linear dependence of the first peak current on the TNT concentration was obtained in the range 4.4 ā 638.4 Ī¼M Lā1.The platinum electrode exhibited an electrochemically stabile behavior for the TNT reduction process. Hence, a Pt electrode could be a suitable material for TNT sensing.Belgrade, Serbia, June 6-10, 201
Application of new polymer-clay nanocomposite materials in purification of water containing phenol derivatives.
Predmet rada ove doktorske disertacije bio je sinteza i karakterizacija aminofunkcionalizovanog
makroporoznog nanokompozita polimera i gline, koji je u
laboratorijskim uslovima ispitan kao sorbens za uklanjanje derivata fenola iz vodenih
rastvora. Nanokompozit poli(glicidilmetakrilata-ko-etilenglikoldimetakrilata) i kiselomodifikovanog
bentonita dobijen je postupkom suspenzione kopolimerizacije preko
slobodnih radikala. Zatim je nanokompozit funkcionalizovan reakcijom sa
dietilentriaminom (deta). Funkcionalizacija je od kljuÄnog znaÄaja za sorpcionu
sposobnost i selektivnost kompozita.
Ispitivani kompozit je uporeÄen sa kopolimerom poli(glicidilmetakrilata-koetilenglikoldimetakrilatom).
UraÄena je karakterizacija nefunkcionalizovanih i
funkcionalizovanih uzoraka (kopolimera i kompozita) hemijskom analizom,
infracrvenom spektroskopijom, skenirajuÄom elektronskom mikroskopijom (SEM),
transmisionom elektronskom mikroskopijom (TEM) i odreÄivanjem teksturalnih
svojstava. TEM analizom potvrÄeno je da sintetisani kompozit ima nanokompozitnu
strukturu i da se najbolje može opisati kao disperzija interkalisanih i razlistanih agregata
u polimernoj matrici.
Pored prisustva funkcionalnih grupa i teksturalna svojstva uzoraka su znaÄajna
za sorpcionu efikasnost. UoÄeno je da se kod nanokompozita, za razliku od kopolimera,
koji je dominantno makroporozan (sa preÄnikom pora > 50 nm), javlja i znaÄajan udeo
mezopora (sa preÄnikom pora od 2 do 50 nm). Prisustvo mezopora uslovljava da
nanokompozit ima veÄu specifiÄnu povrÅ”inu i ukupnu zapreminu pora.
OdreÄivanjem sadržaja amino grupa funkcionalizovanih uzoraka dobijena je
neŔto niža vrednost za kompozit u odnosu na kopolimer Ŕto može biti posledica manje
dostupnosti epoksidnih grupa kod nanokompozita...Amino-functionalized macroporous polymer-clay nanocomposite was
synthesized and fully characterized. This material was investigated under laboratory
conditions as a sorbent for removal of phenol derivatives from water solutions.
Nanocomposite of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) and
acid modified bentonite was prepared by radical suspension copolymerization and
functionalized with diethylenetriamine (deta). The purpose of functionalization was to
enable sorption and selectivity of the composite.
Investigated composite was compared with copolymer poly(glycidyl
methacrylate-co-ethylene glycol dimethacrylate). Nonfunctionalized and functionalized
samples (copolymer and composite) were characterized by chemical analysis, Infrared
Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron
Microscopy (TEM) and their textural properties were determined. TEM analysis
confirmed that the synthesized composite had nanocomposite structure which can be
best described as a dispersion of intercalated and exfoliated aggregates in polymeric
matrix. Besides functional groups, textural properties of samples are also important for
sorption efficiency. It was observed that besides macropores (pore diameter: > 50 nm)
which are characteristics of copolymers, nanocomposite contained a significant amount
of mesopores (pore diameter: 2-50 nm). The presence of mesopores led to higher
specific surface area and total pore volume of nanocomposite. The content of amino
groups in the functionalized composite (CP-SA-deta) was slightly lower than in the
functionalized copolymer (CP-deta). This could be the consequence of the lower
accessibility of epoxy groups in CP-SA-deta..
The galvanostatic reduction on modified platinum electrode and determination of trinitrotoluene in neutral solution
The study of the electrochemical reduction on acetonitrile modified platinum electrode and determination of trinitrotoluene (TNT) in neutral solution by simple galvanostatic technique is presented here. The obtained potential-time responses on the applied constant cathodic current pulses showed two potential transitions before achieving the steady-states, referring to the multi-step reduction process of nitro groups in TNT molecule. The calibration curves of the dependence of the square root of the first transition time (Ļ 0.5) on the TNT concentration were linear in the ranges 4.4 ā 303.8 Ī¼M and 0.09 ā 4.40 Ī¼M for applied constant current of 0.1 mA. The detection limit was 0.09 Ī¼M. The method was tested in the river water. The results indicated the sensitivity of the galvanostatic method for TNT determination in the environmental samples. From the first transition on the E-t curves the characteristics important for the understanding the mechanism of the reduction process were obtained. It was found that four electrons are involved in the reduction process of the first nitro group, indicating that the reduction product in a neutral electrolyte is hydroxylamine.\ud
Keywords
Masivna tromboza abdominalne aorte s distalnom embolijom kao jedina kliniÄka manifestacija COVID-19 infekcije
COVID-19 infection usually presents with respiratory symptoms and fever however several unusual initial presentations of this infection were reported in literature. We report a case of arterial thrombosis as a presenting features of this disease without any other COVID-19-related symptoms. This might lead to delayed COVID-19 diagnosis and isolation of suspected patient causing epidemiologic consequences and increased risk of transmission of the virus inside the hospital in time of pandemic unless timely recognized.Infekcija COVID-19 se obiÄno manifestira respiratornim simptomima i vruÄicom, no u literaturi je opisano nekoliko neuobi-Äajenih poÄetnih simptoma bolesti. Prikazujemo sluÄaj bolesnice s trombozom arterije kao jedinom kliniÄkom prezentacijom ove bolesti, bez drugih uobiÄajenih simptoma vezanih uz COVID-19. Ukoliko se pravovremeno ne prepozna, to može rezultirati odgo-Äenim dijagnosticiranjem i izolacijom suspektnog bolesnika te uzrokovati epidemioloÅ”ke posljedice i poveÄani rizik prijenosa virusa unutar bolnice u doba pandemije
Neuroimaging Techniques in Modern Forensic Psychiatry
Applied neuroscientific knowledge such as brain neuroimaging has widespread application in the medical diagnostic and treatment areas. Neuroscientific progress such as cognitive neuroscience has strong implications in specific medical fields such as forensic psychiatry. Significant progress in forensic psychiatry has affected the practice of law, in which an understanding of the complex relationship among mind, brain, and behavior is becoming necessary. Forensic psychiatry is concerned with the relationship between psychiatric abnormalities and legal violations and crimes. Due to the lack of available biological criteria, assessment, evaluation and therapy in forensic psychiatry have so far been restricted to psychosocial and mental criteria of offender personality. Recent advances in nuclear radiology such as brain imaging techniques (fMRI, DT-MRI, PET, SPECT) allow a closer approach to the neural correlates of personality, moral judgments and decision-making. Introduction of neurobiological criteria (based on advanced neuroimaging techniques) in the field of forensic psychiatry and establishing the rules to what extent such biological criteria will be more reliable choice in evaluating mentally ill offenders would be of fundamental value in the modern forensic psychiatry. Psychosocial and subjective criteria in forensic evaluation will be more accomplished by biopsychosocial and objective criteria. Advances in the neuroimaging techniques bring specificity to the problems underlying the application of neuroscience to criminal law
Sunlight and Incidence of Pterygium on Croatian Island Rab ā Epidemiological Study
The aim of this epidemiologic study, on small island Rab, in North Adriatic Sea, is to estimate correlation between
climatic factors, specially chronic exposure to strong visible and UV light, and appearance of pterygium and exfoliation
syndrome. In the first group of population which live in a village and who are agriculturists and fishermen (480 persons)
appearance of pterygium is in 23% (16% in males and 7% in females), but 0.0% in urban people (61 people). The appearance
of exfoliation syndrome was in the first group of agriculturists and fishermen population in 21%, of which 19% of
males and 2% of females, and in urban people 0.0%. The higher intraocular pressure in exfoliation syndrome was 92%.
All population in this examination were in the highest age (mean age is 65ā80 years). Chronic exposure to sunlight
caused the high percentage appearance of pterygium and exfoliation syndrome
ALLERGOLOGIC EMERGENCIES IN DERMATOLOGY DIAGNOSTIC AND THERAPEUTIC PROCEDURES
Hitna stanja u alergologiji i kliniÄkoj imunologiji sve su ÄeÅ”Äi medicinski javno zdravstveni problem u nas i u svijetu. Äeste su alergijske reakcije od blagih simptoma kao Å”to je svrbež do generaliziranih kožnih, gastrointestinalnih, respiratornih simptoma do anafilaksije i zatajenja kardiovaskularnog sustava. Pri tom su moguÄe reakcije na razliÄite udisajne tvari, hranu i aditive u hrani, strane tvari (krv, lateks i drugo) te brojne poznate antigene i lijekove koji putem imunskih kompleksa i reakcija posredovanih oslobaÄanjem komplementa ili direktnim oslobaÄanjem histamina (opijati ili dekstran) te zbog modulatora metabolizma arahidonske kiseline (npr. NSAID) i drugo. NSAID Äesto uzrokuju astmu, urtikarijski osip, angioedem i joÅ” 35 razliÄitih dermatoloÅ”kih reakcija, posebice kod primjene lijekova koji zahtijevaju hitan terapijski postupak. Reakcije od uboda insekata pojavljuju se ne samo s bolnim infiltratima, nego i diseminiranim osipima i edemom. Suvremene dijagnostiÄke metode, a posebice hitni terapijski postupci, sukladno internacionalnom k oncenzusu (npr. European Allergy White Paper) ukazuju na potrebu ujednaÄavanja stavova u kliniÄkoj praksi. Velik broj bolesnika se lijeÄi zbog alergijskih kožnih bolesti neadekvatno, upuÄuje na testiranja Äesto u fazi aktivne bolesti i kad su pod terapijom, a lijeÄe se kortikosteroidima i antihistaminicima duže no Å”to je potrebno. Suvremeno lijeÄenje hitnih stanja zahtijeva izobraženu osobu, no svaki lijeÄnik treba odgovarati za lijeÄenje akutnih simptoma u svojoj ordinaciji i poznavati postupak za hitno lijeÄenje toÄno odreÄenim lijekovima. AnafilaktiÄne reakcije su rijetke, ali svaki lijeÄnik treba biti pripravan na najteže situacije i poznavati lijeÄenje u hitnom postupku. U radu navodimo najÄeÅ”Äe bolesti za koje je potreban hitan postupak lijeÄenja, a u fazi regresije bolesti dijagnostiÄki postupci.Emergencies in allergology and clinical immunology are quite common and pose a public health problem in Croatia and worldwide. Allergic reactions ranging from mild symptoms such as pruritus to generalized skin eruptions, gastrointestinal and respiratory symptoms to anaphylaxis with cardiovascular emergencies are very common. Reaction develops to inhalant substances, food and food ingredients, various foreign substances (blood, latex, etc.) and many other well known antigens and drugs which are frequent causes of anaphylactic reactions, asthma, generalized urticaria, angioedema. There are 35 different skin reactions induced by drugs through immune complexes, complement mediated reactions and direct histamine liberation (by opiates or dextran) and modulators of arachidonic acid metabolism (such as NSAID). Along with painful infiltrates, insect venom allergy manifests with disseminated exanthema and angioedema. Current diagnostic methods, especially therapeutic procedures for emergencies in concordance with the international consensus of the European Allergy White Paper, require the same procedure in clinical practice. Many patients with different allergic skin diseases are treated inappropriately, some are tested in active phase of the disease, during anti-allergic therapy, and some are administered corticosteroids and antihistamines longer than necessary. Sometimes, the treatment of emergencies requires a person experienced in intensive care medicine. However, any physician might be responsible for the treatment of acute symptoms in his office, and thus has to know the modalities and relevant drugs and treatment essentials. Anaphylactic reactions are rare, but every physician should be prepared for the worst. Due knowledge of the correct management should be a must for all of us. The most common emergencies require emergency treatment and diagnostic procedures upon disease regression
Personal Identification by Eyes
Identification of persons through the eyes is in the field of biometrical science. Many security systems are based on biometric
methods of personal identification, to determine whether a person is presenting itself truly. The human eye contains
an extremely large number of individual characteristics that make it particularly suitable for the process of identifying
a person. Today, the eye is considered to be one of the most reliable body parts for human identification. Systems
using iris recognition are among the most secure biometric systems
- ā¦