Directed hybridization of DNA derivatized nanoparticles into higher order structures

Electric field directed hybridization was used to produce twenty layer nanostructures composed of DNA derivatized nanoparticles. Using an electronic microarray device, DNA nanoparticles could be directed and concentrated such that rapid and specific hybridization occurs only on the activated sites. Nanoparticle layers were formed within 30 s of activation and twenty layer structures completed in under an hour. Results demonstrate a unique combination of bottom-up and top-down techniques for nanofabrication.     

Multiarray sensors with pattern recognition for the detection, classification, and differentiation of bacteria at subspecies and strain levels

This work describes the integration of a fully autonomous electrochemical biosensor with pattern recognition techniques for the detection and classification of bacteria at subspecies and strain level. The system provides a continuous, real-time monitoring of bacteria activity upon exposure to antibiotics. The system utilizes 96-well-type electrodes array (DOX-dissolved oxygen sensor) with principal component analysis (PCA) for rapid and routine classification of different classes of bacteria and related strains. A representative sample of a section of the bacteria kingdom has been analyzed and classified using the proposed DOX-PCA system, including the following: Corynebacterium glutamicum, Micrococcus luteus, Staphylococcus epidermidis, Yersinia ruckeri, Escherichia adecarboxylata, Comamonas acidovorans, Alcaligenes odorans, Bacillus globigii, and three strains of Escherichia coli (K12, SM10, ATCC 25922). The new classification scheme is based on the hypothesis that, under identical experimental conditions, various bacteria consume oxygen at different rates and are affected in different ways by selected antibiotics. Thus, the response of the individual electrode in the array is indirectly altered, compared to that of cells growing on medium, by the addition of the antibiotic. By using three different antibiotics in separate wells, a unique fingerprint can be created for a specific bacterium. With the proposed DOX-PCA system, classification of bacteria was achieved at subspecies and strain level in real time. This study represents a basic research tool that may allow researchers to rapidly detect, quantify, and classify bacteria type at subspecies and strain levels.     

Short-Term Urban Water Demand Prediction Considering Weather Factors

Accurate and reliable forecasting plays a key role in the planning and designing of municipal water supply infrastructures. Recent studies related to water demand prediction have shown that water demand is driven by weather variables, but the results do not clearly show to what extent. The principal aim of this research was to better understand the effects of weather variables on water demand. Additionally, it aimed to offer an appropriate and reliable technique to predict municipal water demand by using the Gravitational Search Algorithm (GSA) and Backtracking Search Algorithm (BSA) with Artificial Neural Network (ANN). Moreover, eight weather factors were adopted to evaluate their impact on the water demand. The principal findings of this research are that the hybrid GSA-ANN (Agent?=?40) model is superior in terms of fitness function (based on RMSE) for yearly and seasonal phases. In addition, it is evidently clear from the findings that the GSA-ANN model has the ability to simulate both seasonal and yearly patterns for daily data water consumption.     

Performance trade-offs in single-photon avalanche diode miniaturization

Single-photon avalanche diodes (SPADs) provide photons' time of arrival for various applications. In recent years, attempts have been made to miniaturize SPADs in order to facilitate large-array integration and in order to reduce the dead time of the device. We investigate the benefits and drawbacks of device miniaturization by characterizing a new fast SPAD in a commercial 0.18 microm complementary metal oxide semiconductor technology. The device employs a novel and efficient guard ring, resulting in a high fill factor. Thanks to its small size, the dead time is only 5 ns, resulting in the fastest reported SPAD to date. However, the short dead time is accompanied by a high after-pulsing rate, which we show to be a limiting parameter for SPAD miniaturization. We describe a new and compact active-recharge scheme which improves signal-to-noise tenfold compared with the passive configuration, using a fraction of the area of state-of-the-art active-recharge circuits, and without increasing the dead time. The performance of compact SPADs stands to benefit such applications as high-resolution fluorescence-lifetime imaging, active-illumination three-dimensional imagers, and quantum key distribution systems.     

Splanchnic and mammary nitrogen metabolism by dairy cows fed steam-rolled or steam-flaked corn

Objectives were to determine net release or uptake of a-amino N, ammonia N, and urea N across portal-drained viscera, liver, splanchnic, and mammary tissues of lactating Holstein cows (n = 6; 109 +/- 9 d in milk) fed alfalfa hay-based total mixed rations (TMR) containing 40% steam-rolled or steam-flaked corn grain. The TMR were offered at 12-h intervals in a crossover design. Blood samples were obtained from indwelling catheters in portal, hepatic, and mammary veins and mesenteric or costo abdominal arteries, every 2 h for each cow and diet. Steam-flaked compared with steam-rolled corn greatly increased in vitro starch hydrolysis (56 vs. 34%). Daily intake of dry matter (18.4 +/- 0.4 kg/d), starch, N, and net energy for lactation by cows were not altered by processing corn; neither were daily yield of milk (29.1 +/- 0.7 kg/d), fat-corrected milk, nor fat-corrected milk per dry matter intake. Steam-flaking tended to increase percent milk protein (2.97 vs. 2.82%; P = 0.07), but not yield, and decrease percent lactose (4.83 vs. 4.94) but not yield. Portal and hepatic blood flows were not affected by diet, nor were net absorption of alpha-amino N and ammonia N. Steam-flaking compared with steam-rolling increased urea N cycling to portal-drained viscera (212 vs. 87 g/d) by 140%, estimated mammary uptake and extraction ratio of alpha-amino N. Flaking versus rolling of corn improved N utilization in dairy cows by increasing urea cycling to the gut and uptake of a-amino N by the mammary gland. Higher mammary uptake of alpha-amino N (78 vs. 50 g/d) by dairy cows fed steam-flaked corn tended to increase milk protein content and may explain the previously observed effects of cows fed steam-flaked versus steam-rolled corn.     

Mercury levels in cord blood and meconium of healthy newborns and venous blood of their mothers: clinical, prospective cohort study

OBJECTIVES: The purpose of this study is to investigate the chronic mercury intoxication in pregnant women and newborns living in Istanbul, Turkey. METHODS: The research was carried out as a prospective with 143 pregnant women and their newborns. Venous blood from the mother, cord blood from the neonate, and meconium were collected for mercury analysis. Frequency of fish and vegetable-eating and the number of teeth filled were investigated. Analyses were made in cold vapor Atomic Absorption Spectrophotometer (AAS, microg/L). RESULTS: Mercury levels were 0.38+/-0.5 microg/L (0-2.34) in venous blood of pregnant women, 0.50+/-0.64 microg/L (0-2.36) in umbilical cord blood and 9.45+/-13.8 microg/g (0-66.5) in meconium. Maternal blood mercury level was lower than the known toxic limit for humans (EPA, 5 microg/L). Mercury levels of the maternal venous blood were significantly correlated with umbilical cord blood. The primary risk factors affecting mercury levels were eating fishmeals more than twice a week and having filled teeth more than five. The fact that the mother had a regular vegetable diet everyday reduced the mercury levels. Increased levels of mercury in the mother and umbilical cord blood could lead to retarded newborns' weight and height. CONCLUSION: Pregnant women living in Istanbul may be not under the risk of chronic mercury intoxication. Fish consumption more than twice per week and tooth-filling of mother more than five may increase mercury level. On the contrary, regular diet rich in vegetable decreases the mercury level.     

An Unconditionally Stable Split-Step FDTD Method for Low Anisotropy

Split-step unconditionally stable finite-difference time-domain (FDTD) methods have higher dispersion and anisotropic errors for large stability factors. A new split-step method with four sub-steps is introduced and shown to have much lower anisotropy compared with the well known alternating direction implicit finite-difference time-domain (ADI-FDTD) and other known split step methods. Another important aspect of the new method is that for each space step value there is a stability factor value that the numerical propagation phase velocity is isotropic.     

Influence of surfactants on properties of electrochemically synthesized pyrrole/1-dimethylaminopyrrole copolymer

The electrochemical copolymerization of pyrrole (Py) and 1-dimethylaminopyrrole (DMAPy) was successfully carried out in the presence of three different types of surfactant (anionic, cationic and non-ionic) by cyclic voltammetric method. The influence of anionic (sodium dodecylbenzenesulfonate) (NaDBS), cationic (tetradecyltrimethylammonium bromide) and non-ionic poly(ethylene oxide)(10) iso-octylphenyl ether (Tween 20) surfactants on the properties of copolymer was investigated. The copolymer has been characterized by the cyclic voltammetry, fourier transform infrared spectroscopy, UV–Vis spectroscopy, scanning electron microscopy, thermogravimetric analysis and conductivity measurements. The results confirmed that the electrochemical reaction of Py and DMAPy in the presence of surfactants generated copolymers. The type of surfactant had an effect on the structural, morphological, thermal and conductivity properties of the copolymers in different ways. According to the initial decomposition temperatures, the thermal stability of the copolymers improved in the presence of surfactants. Py/DMAPy copolymer synthesized in the presence of anionic surfactant NaDBS had the highest initial decomposition temperature (320 °C). The copolymer prepared using various surfactants exhibited different morphologies. The electrical conductivity of pyrrole/1-dimethylaminopyrrole copolymer (8.39 × 10^?3 Scm^?1) was improved using surfactants, especially with anionic surfactant (3.75 × 10^?2 Scm^?1) due to the incorporation of NaDBS into the PPy polymer chain that resulted in a more compact morphology and reduced size of PPy globules.