Misalignment tolerance analysis of free-space optical interconnects via statistical methods

System-level packaging is one of the critical issues that need to be addressed for free space optical interconnections (FSOI) to become useful in desktop systems. The performance of FSOI, e.g., in terms of system bit-error rate, is greatly affected by misalignments in the optical system. Therefore tolerancing, i.e., the ability to analyze and predict the effects of misalignments in the system, is of prime importance to system designers. We introduce an approach in which we study the effects of optical misalignments and other tolerance factors using statistical methods. We use Monte Carlo simulations, design of the experiments, and regression techniques to fit a polynomial equation that expresses the relationship between the system performance and the tolerance factors. This prediction model can be used for design, cost optimization, and quality control purposes. In addition, we perform a sensitivity analysis to determine those tolerance variables that have the greatest effect on system performance.     

Studies of floating dosage forms of furosemide: in vitro and in vivo evaluations of bilayer tablet formulations

For the purpose of enhancement the bioavailability of furosemide (FR), a floating dosage form with controlled release of FR was designed in this study. Because of the lower solubility of active material in the gastric medium, it was first enhanced by preparing an inclusion complex of FR with beta-cyclodextrin (beta-CD) in a 1:1 proportion using the kneading method. Following the design of dosage form, bilayer floating tablets were prepared. After dissolution rate studies were performed using the continuous flow-through cell method, the formulation that provided delivery of active material near the target profile was given to six healthy male volunteer subjects, and in vivo tests were performed. It was determined by radiographs that floating tablets prepared by adding BaSO4 stayed in the stomach for 6 hr. Further, values of the area under the plasma concentration-time curve (AUC) obtained with the floating dosage form were about 1.8 times those of the conventional FR tablet in blood analyses; maximum and minimum plasma concentrations were also found to be between the desired limits. In urine analyses, the peak diuretic effect seen in classical preparations was decreased and prolonged in floating dosage forms. Also, a considerably significant correlation was detected between in vivo results and in vitro data of the dissolution rate, and it was concluded that the modified continuous flow-through cell method is usable for in vitro dissolution rate tests of floating dosage forms.     

Covalent functionalization of single walled carbon nanotubes with peptide nucleic acid: Nanocomponents for molecular level electronics

Imparting molecular recognition to carbon nanotubes (CNTs) by conjugating them with bio-molecules has been an area of great interest as the resulting highly functionalized CNT-bioconjugates find their applications in various fields like molecular level electronics, pharmaceuticals, drug delivery, novel materials and many others. In this work we demonstrate the synthesis of functionally engineered single walled carbon nanotubes (SWNTs)-peptide nucleic acid (PNA) conjugates especially for nanoelectronic applications. Here we exploited the exceptional structural and chemical advantages of PNA (an artificial analogue of DNA) to join SWNTs ropes. SWNT-PNA-SWNT conjugates were synthesized using carbodiimide coupling chemistry and characterized by host of techniques like scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy. The results from different techniques confirm the formation of these conjugates. Theoretical analysis of molecular orbitals obtained by quantum mechanical simulations show that the highest occupied molecular orbital is located on the glutamate linker and that this interface state will align closely to the valence band of the extended SWNT facilitating charge transfer. The unique electrical and structural properties of these conjugates make them a potential candidate for application in CNT based nanodevices.     

Formation of chromium nitride layers on AISI 1010 steel by nitro-chromizing treatment

In this study, chromium nitride coating was realized on AISI 1010 steels by nitro-chromizing treatment. Steel samples were tufftrided at 575 °C for 2 h in the first step of the coating process, and then chromized by pack method in the powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000 °C for 1-4 h. Samples were characterized by scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy, X-ray diffraction (XRD) analysis and Vickers micro-hardness tests. Coating layer formed on the steel samples is smooth and compact and well bonded to the steel matrix. The thickness of chromium nitride layer formed on the steel samples ranged from 5.16±1.48 to 13.45±1.73 μm, depending on the treatment time. The average micro-hardness value of the layer was 1789±59 HV_0.05. The layer consisted of Cr₂N and (Cr,Fe)₂N_(1−x) phases, according to XRD. EDS results showed that coating layer includes chromium and nitrogen.     

Combining molecular imprinted nanoparticles with surface plasmon resonance nanosensor for chloramphenicol detection in honey

The focus of this article is to develop a surface plasmon resonance (SPR) nanosensor to determine chloramphenicol (CAP) using the molecularly imprinted nanoparticles. The CAP imprinted nanoparticles were prepared by miniemulsion polymerization method. Then, the nanoparticles were attached onto the SPR nanosensor surface via temperature‐controlled evaporation. Surface characterization studies were performed with atomic force microscopy and contact angle measurements. Kinetic studies were performed with CAP solutions in the concentration range of 0.155–6.192 nM. Florphenicol (FLP) and thiamphenicol (TAP) having similar chemical structures to the template (i.e., CAP) were chosen as competitors to determine selectivity of the nanoparticles. Selectivity constants were observed as 8.86 for CAP/TAP and 8.36 for CAP/FLP. The detection limit was calculated as 40 ng/kg honey sample. In the light of these results, it was emphasized that the SPR nanosensor is able to recognize CAP selectively and has a potential for real‐time CAP detection in honey sample. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fixed-Bed Pyrolysis of Hazelnut (Corylus Avellana L.) Bagasse: Influence of Pyrolysis Parameters on Product Yields

Fixed-bed slow pyrolysis experiments have been conducted on a sample of hazelnut bagasse to determine particularly the effects of pyrolysis temperature, heating rate, particle size and sweep gas flow rate on the pyrolysis product yields. The temperature of pyrolysis, heating rate, particle size and sweep gas flow rate were varied in the ranges 350–550° C, 10 and 50° C/min, 0.224–1.800 mm and 50–200 cm³/min, respectively. Under the various pyrolysis conditions applied in the experimental studies, the obtained char, liquid, and gas yield values ranged between 26 and 35 wt%, 23 and 34.40 wt%, and 25 and 32 wt%, respectively. The maximum biooil yield of 34.40% was obtained at the final pyrolysis temperature of 500°C, with a heating rate of 10° C/min, particle size range of 0.425–0.600 mm and a sweep gas flow rate of 150 cm³/min.     

Groundwave propagation modeling: problem-matched analyticalformulations and direct numerical techniques

In this overview of groundwave propagation, we address a particular class of propagation scenarios in the presence of surface terrain and atmospheric refractivity. Beginning with idealized analytically solvable models over a smooth spherical Earth, we trace the progression toward more "reality" through physics-based numerical algorithms, operating in the frequency and short-pulse time domain, which take advantage of computational resources. An extensive sequence of simulations for various terrains and atmospheric refractivities, as well as different source-receiver arrangements and operating frequencies, serves to calibrate these algorithms one against the other, and establishes the range of problem parameters for which each is more effective     

Determination of bioclimatic comfort in three different land uses in the city of Erzurum,Turkey

This study was carried out to determine the human bioclimatic conditions in rural, urban and urban forest areas in the conditions of the city of Erzurum, where an extreme continental climate type prevails. Data were obtained over a 10-month period and human bioclimatic conditions in these three different land-use types were evaluated using human bioclimatic indices, suitable for the data obtained. In the study, thermohygrometric index (THI), which assesses air temperature and relative humidity, and “beer garden days” index, which uses the days when temperature at 21:00 is over 20 °C, were used. While in these three areas “hot” and “comfort” ranges were determined to be 10% of the period, the number of “beer garden” days was only 20 days in rural, 15 days in urban forest and 18 days in urban areas of Erzurum. Consequently, it has been determined that the most suitable area for the human comfort in the conditions of Erzurum is in the urban area which is followed by the urban forest and the rural areas, both for each observation time and across the whole period.     

Micro‐ and nanoscale structures of mesiodens dentin: Combined study of FTIR and SAXS/WAXS techniques

A mesiodens is the most common type of supernumerary tooth present in conjunction to normal dentition. A mesiodens may commonly occur in the central region of the upper or lower jaw. A mesiodens is different from normal teeth in terms of structure and shape. The aim of this study is to evaluate the micro‐ and nanoscale structural properties of mesiodens dentin by combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and Fourier transform infrared (FTIR) spectroscopy. Five freshly extracted, noncarious mesiodens and five normal dentin disks prepared from human incisor teeth were compared. Using FTIR, the phosphate‐to‐amide I, carbonate‐to‐phosphate, and carbonate‐to‐amide I band area ratios and the crystallinity index were quantified. SAXS/WAXS were used to study the nanostructure of mesiodens. An increase in the mineral content in the mesiodens dentin with respect to the normal group was found. Crystallinity was also significantly increased and the protein content decreased in the mesiodens dentin compared with that of normal dentin. SAXS/WAXS results revealed that mesiodens dentin has a more calcified tissue. Further, SAXS analysis revealed a nonuniform distribution of dentin fibrils in mesiodens. Microsc. Res. Tech., 78:52–58, 2015. © 2014 Wiley Periodicals, Inc.     

Heterogeneous integration through electrokinetic migration

We apply basic electrophoretic motion to semiconductor materials engineering for development of the next level of heterogeneous integration technology. Furthermore, we demonstrate the utility of these tools in integration of inorganic devices with biological species in order to explore the utility of these tools in biotechnological applications.Electrical and optical addressing techniques are shown to allow for more rapid and parallel patterning of biological species and inorganic objects