A simplified analytical approach to calculation of the electromagnetic behavior of left-handed metamaterials with a graded refractive index profile

We investigated the spectral properties of a new class of nanostructured artificial composite materials with tailored electromagnetic response, i.e. negative refractive index materials, also known as "left-handed" metamaterials. We analyzed structures incorporating both ordinary positive index media and negative refractive index metamaterials where the interface may be graded to an arbitrary degree. Utilizing a modified version of the Rosen-Morse function, we derived analytical expressions for the field intensity and spectral reflection and transmission through a graded interface between positive and negative index materials. We compared our results to numerical solutions obtained using the transfer matrix technique.

Modeling and Simulation of a TFET-Based Label-Free Biosensor with Enhanced Sensitivity

This study discusses the use of a triple material gate (TMG) junctionless tunnel field-effect transistor (JLTFET) as a biosensor to identify different protein molecules. Among the plethora of existing types of biosensors, FET/TFET-based devices are fully compatible with conventional integrated circuits. JLTFETs are preferred over TFETs and JLFETs because of their ease of fabrication and superior biosensing performance. Biomolecules are trapped by cavities etched across the gates. An analytical mathematical model of a TMG asymmetrical hetero-dielectric JLTFET biosensor is derived here for the first time. The TCAD simulator is used to examine the performance of a dielectrically modulated label-free biosensor. The voltage and current sensitivity of the device and the effects of the cavity size, bioanalyte electric charge, fill factor, and location on the performance of the biosensor are also investigated. The relative current sensitivity of the biosensor is found to be about 1013. Besides showing an enhanced sensitivity compared with other FET- and TFET-based biosensors, the device proves itself convenient for low-power applications, thus opening up numerous directions for future research and applications

Subwavelength hole arrays with nanoapertures fabricated by scanning probe nanolithography

Owing to their surface plasmon-based operation, arrays of subwavelength holes show extraordinary electromagnetic transmission and intense field localizations of several orders of magnitude. Thus they were proposed as the basic building blocks for a number of applications utilizing the enhancement of nonlinear optical effects. We designed and simulated nanometer-sized subwavelength holes using an analytical approach. In our experiments we used the scanning probe method for nanolithographic fabrication of subwavelength hole arrays in silver layers sputtered on a positive photoresist substrate. We fabricated ordered nanohole patterns with different shapes, dispositions and proportions. The smallest width was about 60 nm. We characterized the fabricated samples by atomic force microscopy

Identification of deep trap levels from thermally stimulated current spectra of semi-insulating CdZnTe detector material

Deep trap levels in the semi-insulating (SI) CdZnTe detector material were characterized by simultaneous multiple peak analysis based on thermally stimulated current (TSC) measurements. In our TSCs that have been published previously electron hole pairs were created through the use of proton beam irradiation. Charge carriers were captured in deep traps and afterward released by thermal emission, which was recorded in the 90–300 K range. We showed that the obtained TSC spectra could be well fitted with a unique set of 14 different deep traps, which were all simultaneously and completely characterized. The obtained trap data are in good accordance with earlier deep trap characterizations of the other authors obtained on similar SI CdZnTe materials using different methods

Fumonisins and co-occurring mycotoxins in north Serbian corn

The presence of fumonisin has not been regulated in the legislation of the Republic of Serbia. Therefore, the data on contamination of cereals, especially corn, which is highly susceptible to contamination by this toxin, are not sufficient. This paper presents the results of testing the corn samples collected in the autumn 2009 on the territory of Bačka. Samples were analyzed for the contents of fumonisins and it was determined whether there is a correlation between the moisture content, total number and class of fungi, as well as the content of aflatoxin, ochratoxin and zearalenone. Using enzymatic immunoaffinity method it was discovered that the highest percentage of samples were contaminated with fumonisins, which was probably due to the presence of Fusarium molds as the most abundant ones. The positive samples contained fumonisin in the concentrations from 0.030 to 1.52 mg kg−1. The influence of the climate and moisture content of grain on fungal contamination and mycotoxin production was analyzed in order to investigate the predictability of the presence of mycotoxins

Prisustvo zearalenona u najčešće uzgajanim sortama pšenice u Srbiji

A total of 45 samples of wheat from three different locations in Vojvodina were analyzed for the presence of zearalenone. Analytical methods based on clean-up by solid-phase extraction (SPE) columns and detection by liquid chromatography were used after validation. Limit of detection for ZEA in wheat was 18.6 μg/kg and the limit of quantification was 56.5 μg/kg. Recovery values ranged between 86% and 97%. The occurrence of ZEA in wheat was rather high with 53.3% of positive samples with the average value of 330 μg/kg. Incidences were found from 68 μg/kg to 1079 μg/kg. Contamination levels were above the established maximum limit for unprocessed cereals, other than maize, in as many as seventeen samples. These results were compared to the results of investigation of deoxynivalenol and fumonisin content, established in our previous work on the same samples. The results obtained were also compared to those of the neighboring countries where the relevant data existed and to the data of previous studies in our country.Na prisustvo zearalenona analizirano je ukupno 45 uzoraka pšenice sa tri različite lokacije u Vojvodini. Korišćene su analitičke metode zasnovane na prečišćavanju ekstrakcijom na čvrstoj fazi, te kvantifikacija tečnom hromatografijom, nakon validacije metode. Granica detekcije za zearalenon u pšenici je iznosila 18,6 μg/kg, a granica određivanja 56,5 μg/kg. Efikasnost metode je bila u opsegu od 86% do 97%. Zearalenon je bio prisutan u 53,3% ispitivanih uzoraka, sa prosečnim sadržajem od 330 μg/kg. Dobijene vrednosti sadržaja zearalenona su bile u opsegu od 68 μg/kg do 1079 μg/kg. U čak sedamnaest uzoraka je pronađena koncentracija ovog toksina koja prevazilazi maksimalni dozvoljeni sadržaj zearalenona u netretiranim žitaricama. Ovi rezultati su upoređeni sa vrednostima sadržaja deoksinivalenola i fumonizina u istim uzorcima dobijenim u našim prethodnim istraživanjima. Rezultati su takođe upoređeni sa dostupnim rezultatima dobijenim u našoj i susednim zemljama tokom prethodnih godina

Nonlinear Transport and Current Fluctuation in an AB Ring with a Quantum Dot

Nonequilibrium steady states are explicitly constructed for a noninteracting electron model of an Aharonov-Bohm (AB) ring with a quantum dot (QD) with the aid of asymptotic fields. The Fano line shapes and AB oscillations are shown to strongly depend on the bias voltage. Current fluctuations are studied as well.Comment: 4pages, 6figure

Alternative site testing of blood glucose in children and adolescents with type I Diabetes

Nekoliko studija koje su uključivale odrasle osobe sa šećernom bolešću tipa 1 (T1ŠB) ukazalo je na to da rezultati mjerenja glukoze u krvi (GUK) na alternativnim mjestima (AM) i iz jagodice prsta nisu istovjetni. Različitosti su uočene u mjerenjima nakon obroka, nakon davanja inzulina, tijekom i nakon tjelesne aktivnosti. Naše ispitivanje je provedeno radi uvida da li sličnosti razine GUK s AM uočene u odraslih nalazimo u djece i adolescenata. Mjerenje GUK je obavljeno iz kapilarne krvi jagodica prsta i podlaktica, prije doručka i prije večere, ali najmanje dva sata nakon davanja inzulina i dva sata nakon obroka, i to OneTouch*Ultra samomjeračem (LifeScan). Studiji su pristupila 24 ispitanika s T1ŠB, sudionika ljetnog kampa u Dalmaciji. Nakon završetka kampa ispitanici su intervjuirani o iskustvima s AM. Ukupno je obavljeno 217 mjerenja iz AM i jagodice prsta. Linearna regresija pokazala je da izmjerene razine GUK iz AM koreliraju s razinama iz jagodice prsta (p<0,001, R=0,96). Analizom pomoću tzv. Clarkove mrežne analize greške, gdje je referentna vrijednost GUK iz jagodice prsta, 89,9% razine GUK iz AM bilo je u zoni A, 8,3% u zoni B, 2% u zoni D. Tzv. Parkesova analiza mrežne greške pokazala je 90,3% rezultata iz AM u zoni A, 10% u zoni B te niti jedan u zonama C i D. U 37% ispitanika postoji manji subjektivni osjećaj boli, a 46% njih ne osjeća bol pri korištenju AM. Njih 25% ističe jednostavnost mjerenja pri korištenju AM, a samo 29% će češće koristiti AM u kućnim uvjetima s obzirom na mjerenja u kampu. Povremeno ili rijetko će koristiti AM 71% ispitanika (42% zbog duljeg mjerenja, a 58% zbog težeg dobivanja krvi za mjerenje, odnosno zbog vidljivih tragova uboda). Tijekom trajanja kampa razine GUK korištenjem AM dobro koreliraju s razinama GUK iz jagodice prsta. Izneseno pokazuje da uz dobro usvajanje uputa, uporaba AM donosi objektivne i sigurne rezultate GUK.Several previous studies in adults with type 1 diabetes have documented that glucose levels obtained at alternative sites and at fingertip are not the same, a difference was noticed after a meal, after insulin application or during and after exercise. This study was done specifically to look at alternative site testing (AST) to determine if the site differences previously observed in adults are also found in children and adolescents. Glucose measurements were made using OneTouch Ultra System at fingertip and forearm sites, before breakfast and dinner, but at least two hours after insulin application and two hours after a meal. Twenty-four diabetics attending a summer camp in Dalmatia participated in the testing. At the completion of the camp, the children were questioned about their experience with AST. A total of 217 forearm measurements were made. Linear regression analysis showed that forearm glucose values were highly correlated with fingertip values (p<0.001, R=0.96). Using Clarke Error Grid analysis with fingertip readings as the reference values, 89.9% of values fell in zone A, 8.3% in zone B, 2% fell in zone D. Parkes Error Grid analysis showed 90.3% of values in zone A, 10% in zone B and none in zone C and D. Although 37% of the diabetics examined had a slight subjective feeling of pain, 46% did not feel pain using AST, 25% emphasized the simplicity of measuring blood glucose using AST and only 29% will use AST more frequently at home in regards to using it at the summer camp. 71% will periodically or rarely use AST (41% because it requires more time and 58% because it was harder to obtain blood for measurement or visible stab wounds were present). Glucose values obtained from forearm sites in children and adolescents studied in real life at the diabetic camp correlated closely with fingertip values. This suggests that when children follow the current guidlines for AST largely developed in adults, the results are reliable and can safely be utilized

Correlation between the limit values of laboratory and clinical mycotoxicosis

Analysis of feed for the presence of fungi and mycotoxins is a request necessary to meet in order to ensure a healthy and economical production in livestock. These tests are related to legal regulation which prescribes the maximum legislated content (MLC), both for the presence of mycotoxins and the total number of fungi in certain feeds. Health problems that can occur during the production of animals are sometimes caused by the presence of mycotoxins in the feed. Laboratory testing is a good practice to confirm a suspicion, and allows timely treatment of contaminated feed. Potential problems arise under circumstances when there is a clinical outcome of mycotoxicosis and animal and laboratory findings suggest that the obtained values are below the level that is within the MLC. For these reasons, the subject of our research was to investigate the occurrence of mycotoxins and mold in feed, as well as the clinical presentation for animals that were fed with the feed with allowed values of these agents according to the recommended levels. The aim of this paper was to highlight the problems associated with clinical correlation of sick animals and laboratory findings, and suggest their overcoming. In the period of one year, a total of 176 samples of feed (complete mixture for broilers, corn and soy products) were examined for the presence of fungi, 106 samples were examined for the presence of mycotoxins and 26 flocks of broilers and turkeys were clinically observed. Standard methods were used for isolation of molds and the ELISA test was used for the detection of mycotoxins. Clinical and pathomorphological observation of the flocks was done to determine the natural indicators of production. Studies indicated a problem because clinical and pathomorphological findings in some cases were not correlated with laboratory findings of molds and mycotoxins in the feed, and in some cases it did not necessarily mean that the animals were healthy. Synergism and cumulative effects of mycotoxins, on the one hand, and the characteristics of each species and product category on the other hand, can create specific circumstances that can lead to disease and can increase even though the values prescribed by legislation have been met. [Projekat Ministarstva nauke Republike Srbije, br. TR 031071