Tehnologija forenzičkog ispitivanja bakarne žice nakon požara

Technical forensics is a very broad scientific field. This paper reports one of its aspects, which refer to the testing of electrical conductors following a fire in order to identify the real cause of its appearance, namely providing information whether or not the electric cord damage caused the fire and to offer contribution to the authorities. For this purpose, sectional tests of copper electric cord were conducted using microstructure optical microscope as well as X-ray diffraction analysis. The sample preparation process has been also described. The interpretation of the obtained results with the adopted conclusions based on the above-mentioned tests was presented. Based on these analyses, it was concluded that there was a local melting of the conductors influenced by high temperatures achieved in oxygen atmosphere, and that melting was apparent within all samples.Tehnička forenzika je jako široka naučna oblast. U ovom radu će se govoriti o jednom njenom segmentu koji se odnosi na ispitivanje električnih provodnika nakon požara, u cilju otkrivanja njegovog stvarnog uzroka, tj. prihvatanja ili odbacivanja kvara na elektoinstalacijama kao uzroka požara i pribavljanja informacija istražnim organima za rašavanje postavljenog zadatka. U tu svrhu su izvršena mikrostrukturna ispitivanja preseka bakarne žice korišćenjem optičkog mikroskopa i rendgenostrukturna analiza istih. Opisan je, takođe, i proces pripreme uzoraka kao i tumačenje dobijenih rezultata sa zaključcima donesenim na osnovu pomenutih rezultata ispitivanja. Na osnovu urađenih analiza je zaključeno da je došlo do lokalnog topljenja provodnika pod dejstvom visoke temperature u atmosferi kiseonika, a topljenje je uočeno kod svih ispitivanih uzoraka

Polimeri u kriminalistici - otkrivanje latentnih tragova otisaka prstiju - od ideje do praktične primene

The identification of latent fingerprints is crucial for the security agencies in order to identify persons suspected of having committed criminal acts. Latent prints often remain as random impressions onto the surfaces of various objects. Huge progress has been made in the identification processes using rolled and plain impressions fingerprints, while detection and comparison of latent prints still remains a challenging task. In addition to the existing standardized methods, in this paper the possible utilization of natural and synthetic polymers and their conjugates with the same goal will be reviewed, by means of latent fingerprints detection and development.Identifikacija latentnih otisaka papilarnih linija od ključne je važnosti za bezbednosne službe u identifikaciji osoba osumnjičenih za izvršenje kriminalnih dela. Latentni otisci ostaju kao slučajni utisci na površinama najrazličitijih objekata. Ogroman napredak je postignut u identifikaciji pomoću valjanih otisaka prstiju, dok upoređivanje latentnih otisaka ostaje izazov. Pored postojećih, kriminalističkim tehničarima poznatih standardizovanih metoda za otkrivanje i razvijanje latentnih tragova otisaka papilarnih linija, u radu je dat pregled mogućnosti upotrebe prirodnih i sintetskih polimera i njihovih konjugata. Novije metode detekcije uključuju primenu savremenih (nano)materijala, nanokristala i nanokaiševa za razvijanje latentnih otisaka prstiju, sa visokom osetljivošću, dobrim kontrastom, visokom selektivnošću i efikasnošću i niskim pozadinskim šumom, na različitim podlogama. Sinteza i primena svih opisanih materijala zahtevaju dalje poboljšanje performansi već postojećih sistema za detekciju latentnih otisaka papilrnih linija, ali i otvaraju mogućnosti sinteze potpuno novih takvih sistema

The synthesis of pH- and temperature-sensitive hydrogels of itaconic acid as carriers for immobilization of lipase from Candida rugosa

U ovom radu su, kopolimerizacijom preko slobodnih radikala, sintetisani temperaturno- i pH-osetljivi hidrogelovi na bazi N-izopropilakrilamida (NiPAAm) i itakonske kiseline (IK) različitog sastava i stepena umreženja. Karakterizacija sintetisanih uzoraka je izvedena bubrenjem, ispitivanjem mehaničkih svojstava, skenirajućom elektronskom mikroskopijom, Furijeovom transformacijskom infracrvenom analizom i mikroskopijom atomskih sila. Potvrđeno je da su sadržaj umreživača i sastav reakcione smeše uticali na strukturu hidrogela, mehanička svojstva, morfologiju i kinetiku bubrenja. U drugom delu rada izvedena je imobilizacija enzima, a kao model jedinjenje korišćena je lipaza iz Candida rugosa (CRL). Imobilizacija lipaze je izvedena na dva načina, „in situ” polimerizacijom (Metoda I), i bubrenjem prethodno sintetisanih suvih uzoraka u rastvoru lipaze (Metoda II), uz variranje sadržaja lipaze. Pokazano je da prisustvo itakonske kiseline i lipaze u nosaču utiče na bubrenje i mehanička svojstva hidrogela i na aktivnost enzima. Utvrđene su optimalne vrednosti pH i temperature za imobilisanu lipazu. Ispitana je i stabilnost imobilisane lipaze pri skladištenju tokom 60 dana na različitim temperaturama. Poređenjem složenosti izvođenja imobilizacije, aktivnosti imobilisane lipaze, kao i ekonomičnosti i efikasnosti primene, utvrđeno je da Metoda I ima prednost nad Metodom II. Na osnovu dobijenih rezultata, hidrogel sa imobilisanom lipazom koji je pokazao najbolja svojstava, je primenjen kao biokatalizator u reakciji sinteze n-amil-izobutirata. Sinteza je izvedena esterifikacijom izobuterne kiseline i n-amil alkohola u n-heksanu. Ispitani su i optimizovani parametri reakcije i studija ponovnog iskorišćenja biokatalizatora. Takođe, ispitana je mogućnost potencijalne primene ovih hidrogelova za kontrolisano otpuštanje lekovitih supstanci. Spektrofotometrijskom analizom je utvrđeno da profil i kinetika otpuštanja lipaze mnogo zavise od strukture hidrogela i pH vrednosti okoline. Potvrđeno je da sve formulacije hidrogelova omogućuju očuvanje visoke aktivnosti lipaze i nakon otpuštanja u uslovima koji bi izazvali denaturaciju enzima koji nije zaštićen u gelu. Podešavanjem sastava kopolimera P(NiPAAm/IK) i stepena umreženja ovi hidrogelovi se mogu koristiti kao pogodne matrice za imobilizaciju enzima i njihovu primenu kao biokatalizatora u enzimskim reakcijama. Takođe, moguća je njihova primena kao nosača za kontrolisano otpuštanje proteina u biološki aktivnom obliku.Temperature- and pH-sensitive hydrogels, based on N-isopropylacrylamide (NiPAAm) and itaconic acid (IA) were synthesized by free radical crosslinking copolymerization by varying comonomer and crosslinking agent content. Characterization of the samples was performed by the swelling studies, testing mechanical properties, Scanning Electron Microscopy, Fourier transform Infrared Spectroscopy and Atomic Force Microscopy. It was confirmed that the degree of crosslinking and hydrogel composition had impacts on the hydrogel structure, mechanical properties, morphology and swelling kinetics. In order to immobilize enzyme, lipase from Candida rugosa (CRL) was used as a model compound. Immobilization of lipase was performed by „in situ― polymerization (Method I), and by swelling of previously synthesized xerogels in lipase solution (Method II), with lipase content variation. It has been shown that itaconic acid and lipase presence in the hydrogel affect the swelling and mechanical properties of hydrogel and enzyme activity. The optimal pH and temperature values for immobilized lipase were defined. The stability of the immobilized lipase at different temperatures was determined during 60 days. It was confirmed that Method I was preferable than Method II, concerning lipase ease of immobilization, its activity, economical and efficiency aspects of its application. Based on these criteria, the hydrogel with immobilized lipase, showing the best properties, was selected and used as biocatalyst in ester synthesis reactions. Synthesis of n-amyl isobutyrate is carried out by esterification of isobutyric acid and n-amyl alcohol in n-hexane. Reaction parameters and the reusability study of the biocatalyst have been evaluated and optimized. The possibility of potential application of these hydrogels in drug controlled release systems was tested. Spectrophotometric analysis showed that the lipase release kinetics depended on hydrogel structure and environmental pH. It was confirmed that all formulations of hydrogels enable the preservation of high activity of lipase even after release conditions that would provoke denaturation of the enzyme if it was not protected in the gel. It was concluded that by adjusting the P(NiPAAm/IA) copolymer composition and the crosslinking degree these hydrogels can be used as a suitable matrix for the enzyme immobilization and their application as biocatalyst in enzyme reactions. It was also possible to use them as carriers for protein controlled release in a biologicaly active form, as well

The application of chitosan-based micropowders in development of latent fingermarks

Latent fingermarks are common type of traces found at the crime scene. Therefore, their visualization and enhancement are widely used techniques in identification of offenders and accomplices by law enforcement agencies worldwide. Chemical and physical methods seemed to be reliable for that purpose and have now been used for years. Therefore, researchers focus their work in order to discover new methods for detection and visualization of latent fingermarks. In this regard, the usage of polymeric materials, especially biopolymers, has not yet been sufficiently tested, and scientific public is almost unaware of the potential of these materials in forensic science. In this paper, conjugates based on chitosan were obtained by the precipitating method and their application in detection and visualization of latent fingermarks was examined. The results demonstrated that this bio-based powder system could be potentially used as substitutes for commercially used powders in detecting and visualizing of latent fingermarks

Višeslojne ugljenične nanocevi kao nosač lipaze za organsku sintezu: pregled najnovijih trendova

Lipase-catalyzed organic reactions have been widely practiced in the past three decades. Especially interesting are insoluble/immobilized forms due to providing a possibility of facile use and recyclability, thus reducing process costs, and making the procedure more environmentally friendly. Carbon-based supports have been extensively exploited for this purpose, because of neutral and biodegradable nature and thermal and chemical stability. Their high specific surface area, characteristic surface morphology and lower mass transfer resistances play a vital role in the performance of the attached enzyme. This review paper presents an overview of the main aspects of lipase immobilized on multi-walled carbon nanotubes (MWCNTs). Moreover, different immobilization strategies to achieve a biocatalyst with improved performances are discussed. Furthermore, as lipases are considered to have high commercial worth for synthesis of valuable organic molecules, the second part of the paper is dedicated to the overview of the most important industrial sectors in which these nanobiocatalysts have been used. In specific, applications in biodiesel production, flavour ester synthesis and racemization are summarized.Lipaze su poslednjih decenija široko rasprostanjeni katalizatoriu raznovrsnim organskim reakcijama. Posebno su interesantne u imobilisanom/nerastvornom obliku jer je na ovaj način olakšana njihova upotreba uz mogućnost recikliranja i ponovne upotrebe čime se smanjuju troškovi samog procesa i postupak je ekološki prihvatljiviji. Kao nosači za vezivanje nanomaterijali na bazi ugljenika, posebno ugljenične nanocevi, su našli primenu zbog svojih izuzetnih fizičkih, mehaničkih i hemijskih svojstava. Njihova velika specifična površina, karakteristična površinska morfologija i smanjen otpor prenosu mase igraju vitalnu ulogu u performansama vezanog enzima. Ovaj pregledni rad predstavlja prikaz glavnih aspekata lipaze imobilisane na višeslojne ugljenične nanocevi i različitih strategija imobilizacije za dobijanje biokatalizatora sa poboljšanim svojstvima. Takođe, kako su lipaze enzimi od velikog komercijalnog značaja za organsku sintezu i primenu u biotehnologiji, drugi deo rada posvećen je pregledu najvažnijih industrijskih sektora u kojima su ovi nanobiokatalizatori našli primenu. Shodno tome, dat je pregled proizvodnje biodizela, mirisnih estara i racemizacij

Detection and enhancement of latent fingerprints using dextran-based biopolymer powders obtained from anthocyanin solution

Dextran is extensively exploited in medicine and pharmacy, but, currently no studies using this biopolymer as a powder system for enhancement of latent fingerprints were published. In this paper four different formulations of dextran-based biopolymer powders, obtained by simple precipitation of dextran within anthocyanin solution, were synthetized and characterized in order to determine potential of these biopowders in forensic application. Since detrimental effect on humans is often present while routinely employing commercial dusting methods, the main advantage of prepared dextran-based biopowders are their non-toxic properties, contributing to the safer/healthier operating conditions. The interactions between components of the systems were confirmed by FT-IR analysis. Optical microscopy was used to determine the size of the prepared biopowders, while simultaneously confirmed the interaction between powders and the sweat/lipid residues present in the latent trace. The results demonstrated the potential of novel dextran-based biopowders to supplement routinely employed physical systems in visualizing latent fingerprints

Characterization and potential application of dextran-based biopolymer powder obtained from Hydrangea macrophylla liquid anthocyanins extract by ultrasonic extraction

Biopolymers have numerous advantages, such as their biodegradable, non-toxic, non-inflammatory and biocompatible properties, and, therefore, have a potential for various applications. In this paper dextran-based biopolymer powder, obtained from Hydrangea macrophylla liquid anthocyanins extract by ultrasonic extraction and simple precipitating method, was synthetized and characterized in order to determine its properties and potential application. Attenuated total reflectance Fourier-transform infrared spectroscopy (ATR FT-IR) analyses showed interactions between the components of the system. Optical microscopy suggested that the prepared biopowder formulation was small and somewhat uniform in size, and also showed its easy binding to the fingerprint residues. Additionally, the prepared biopolymer powder was used to visualize latent fingerprints left on different non-porous and semi-porous surfaces, i.e. flat wood, glass, plastic and rubber. The results demonstrated the potential of the obtained dextran-based biopowder to complement routinely applied systems in developing latent fingerprints

Forecasting River Water Levels Influenced by Hydropower Plant Daily Operations using Artificial Neural Networks

Multipurpose water systems are used to deal with multiple objectives related to the usage of water for daily human activities. These activities are often conflicted which creates a challenging water management task. To provide reliable water resources management decision support tools for successful forecasting of hydraulic data (river flows and water levels) are essential. This research presents an approach for forecasting river water levels influenced by hydropower plant operations using artificial neural networks. This approach estimates hourly water level fluctuations at the control location using the water levels and hydropower plant discharge data as input. This tool can be used for fast assessment of different hydropower plant operation plans and help in choosing the optimal one. This water level forecasting procedure is applied and tested on the Iron Gate water system, placed on the Danube River, to deal with multiple objectives in water system management (hydropower production, flood protection, and inland navigation) and shows promising results

Immobilization of Horseradish Peroxidase on Magnetite-Alginate Beads to Enable Effective Strong Binding and Enzyme Recycling during Anthraquinone Dyes’ Degradation

The aim of this study was to investigate covalent immobilization of horseradish peroxidase (HRP) on magnetic nanoparticles (Mag) encapsulated in calcium alginate beads (MABs) for color degradation, combining easy and fast removal of biocatalyst from the reaction mixture due to its magnetic properties and strong binding due to surface alginate functional groups. MABs obtained by extrusion techniques were analyzed by optical microscopy, FEG-SEM and characterized regarding mechanical properties, magnetization and HRP binding. HRP with initial concentration of 10 mg/gcarrier was successfully covalently bonded on MABs (diameter ~1 mm, magnetite/alginate ratio 1:4), with protein loading of 8.9 mg/gcarrier, immobilization yield 96.9% and activity 32.8 U/g. Immobilized HRP on MABs (HRP-MABs) was then used to catalyze degradation of two anthraquinonic dyes, Acid Blue 225 (AB225) and Acid Violet 109 (AV109), as models for wastewater pollutants. HRP-MABs decolorized 77.3% and 76.1% of AV109 and AB225, respectively after 15 min under optimal conditions (0.097 mM H2O2, 200 mg of HRP-MABs (8.9 mg/gcarrier), 0.08 and 0.1 g/mg beads/dye ratio for AV109 and AB225, respectively). Biocatalyst was used for 7 repeated cycles retaining 75% and 51% of initial activity for AB225 and AV109, respectively, showing potential for use in large scale applications for colored wastewater treatment