442 research outputs found

    Enhanced voltage generation through electrolyte flow on liquid-filled surfaces.

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    The generation of electrical voltage through the flow of an electrolyte over a charged surface may be used for energy transduction. Here, we show that enhanced electrical potential differences (i.e., streaming potential) may be obtained through the flow of salt water on liquid-filled surfaces that are infiltrated with a lower dielectric constant liquid, such as oil, to harness electrolyte slip and associated surface charge. A record-high figure of merit, in terms of the voltage generated per unit applied pressure, of 0.043 mV Pa-1 is obtained through the use of the liquid-filled surfaces. In comparison with air-filled surfaces, the figure of merit associated with the liquid-filled surface increases by a factor of 1.4. These results lay the basis for innovative surface charge engineering methodology for the study of electrokinetic phenomena at the microscale, with possible application in new electrical power sources

    A plausible mechanism for the evolution of helical forms in nanostructure growth

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    The observation of helices and coils in nano-tube/-fiber (NT/NF) syntheses is explained on the basis of the interactions between specific catalyst particles and the growing nanostructure. In addition to rationalizing nonlinear structure, the proposed model probes the interplay between thermodynamic quantities and predicts conditions for optimal growth. Experimental results on the effect of indium catalyst on affecting the coil pitch in NTs and NFs are presented

    Three-way electrical gating characteristics of metallic Y-junction carbon nanotubes

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    Y-junction based carbon nanotube (CNT) transistors exhibit interesting switching behaviors, and have the structural advantage that the electrical gate for current modulation can be formed by any of the three constituent branches. In this letter, we report on the gating characteristics of metallic Y-CNT morphologies. By measuring the output conductance and transconductance we conclude that the efficiency and gain depend on the branch diameter and is electric field controlled. Based on these principles, we propose a design for a Y-junction based CNT switching device, with tunable electrical properties

    A study of correlation of endometrial morphology and subendometrial vascularity with pregnancy rate in fresh and frozen embryo transfer cycles

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    Background: Aim of the study was to evaluate the correlation of endometrial morphology and sub endometrial vascularity with pregnancy rate in fresh and frozen embryo transfer cycles.Methods: Prospective, non-randomized observational study done on 76 women undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment at a tertiary health care center. Woman with tubal factor, male factor and unexplained infertility were included in the study. Parameters like endometrial thickness, endometrial pattern, endometrial blood flow were correlated to clinical outcomes such as implantation and clinical pregnancy rates. Independent two-tailed t-test and chi-square test was used as a part of statistical analysis.Results: There is no significant difference in distribution of mean age, mean duration of infertility, cause of infertility, mean basal follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), progesterone (P4), anti-Mullerian hormone (AMH), total gonadotropin dose, median E2 (on day of trigger), median P4 (on day of trigger), number of embryos transferred and endometrial thickness between group of cases with positive and negative pregnancy in our study group. Whereas body mass index (BMI), blastocyst quality of embryo transferred, triple-line pattern of endometrium and endometrial blood flow reaching zone 4 were found to be significant in the study group.Conclusions: A combination of endometrial thickness and Doppler analysis of endometrial blood flow was a simple and effective tool to improve pregnancy rates in hormone replacement treatment-frozen embryo transfer (HRT-FET) cycles and should be incorporated into routine clinical practice. In addition, this can help us reduce the number of embryos to be transferred and hence, the multiple pregnancies and the associated complications.

    FORMULATION AND CHARACTERIZATION OF SUSTAINED RELEASE COATED MATRIX GRANULES OF METFORMIN HYDROCHLORIDE

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    Objective: Metformin hydrochloride is a biguanide antihyperglycemic agent which is a generally recommended first-line drug for the treatment of diabetes mellitus (Type II). The purpose of this investigation is to prepare sustained release matrix granules of metformin hydrochloride which are coated to extend the drug release over a longer time period.Methods: Metformin hydrochloride granules were prepared by mixing all the dry powders in a V-cone blender and wetting the powder mix with aqueous solution of hydroxypropyl methyl cellulose K100. The prepared granules (MG1-MG5) were investigated for drug release. The batch of granules which exhibited extended release for up to 4 h was coated in a standard coating pan with blends of Eudragit RS and RL to further enhance release period. These were marked as coated metformin granules (CMG3) and CMG4 which were later filled into empty capsules. The granules were characterized for micromeritic properties, percentage yield, particle size distribution, percentage of drug content, and in vitro release of the drug.Results: All the formulations showed percentage yield in the range of 77.66–82.86% and drug content in the range of 78.23–96.62%. CMG3 showed drug release of 97.02% for 12 h. Fourier-transform infrared spectroscopy and differential scanning calorimetry studies indicated that no possible interaction existed between the drug and the polymers used. Scanning electron microscopy images revealed that the granules were spherical in shape with smooth surface and completely covered with a coating of polymer. Kinetic analysis of drug release confirmed that drug release followed zero-order kinetics where it is independent of the concentration.Conclusion: From the results, it was analyzed that design of coated granules employing the polymers used in the present work can produce a sustained release of the drug over a period of 12 h

    Control of carbon nanotube morphology by change of applied bias field during growth

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    Carbon nanotube morphology has been engineered via simple control of applied voltage during dc plasma chemical vapor deposition growth. Below a critical applied voltage, a nanotube configuration of vertically aligned tubes with a constant diameter is obtained. Above the critical voltage, a nanocone-type configuration is obtained. The strongly field-dependent transition in morphology is attributed primarily to the plasma etching and decrease in the size of nanotube-nucleating catalyst particles. A two-step control of applied voltage allows a creation of dual-structured nanotube morphology consisting of a broad base nanocone (~200 nm dia.) with a small diameter nanotube (~7 nm) vertically emanating from the apex of the nanocone, which may be useful for atomic force microscopy

    TScan–Stationary LiDAR for Traffic and Safety Applications: Vehicle Interpretation and Tracking

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    To improve traffic performance and safety, the ability to measure traffic accurately and effectively, including motorists and other vulnerable road users, at road intersections is needed. A past study conducted by the Center for Road Safety has demonstrated that it is feasible to detect and track various types of road users using a LiDAR-based system called TScan. This project aimed to progress towards a real-world implementation of TScan by building two trailer-based prototypes with full end-user documentation. The previously developed detection and tracking algorithms have been modified and converted from the research code to its implementational version written in the C++ programming language. Two trailer-based TScan units have been built. The design of the prototype was iterated multiple times to account for component placement, ease of maintenance, etc. The expansion of the TScan system from a one single-sensor unit to multiple units with multiple LiDAR sensors necessitated transforming all the measurements into a common spatial and temporal reference frame. Engineering applications for performing traffic counts, analyzing speeds at intersections, and visualizing pedestrian presence data were developed. The limitations of the existing SSAM for traffic conflicts analysis with computer simulation prompted the research team to develop and implement their own traffic conflicts detection and analysis technique that is applicable to real-world data. Efficient use of the development system requires proper training of its end users. An INDOT-CRS collaborative process was developed and its execution planned to gradually transfer the two TScan prototypes to INDOT’s full control. This period will be also an opportunity for collecting feedback from the end user and making limited modifications to the system and documentation as needed

    Guidelines for Evaluating Safety Using Traffic Encounters: Proactive Crash Estimation on Roadways with Conventional and Autonomous Vehicle Scenarios

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    With the expected arrival of autonomous vehicles, and the ever-increasing levels of automation in today’s human driven vehicles, road safety is changing at a rapid pace. This project aimed to address the need for an efficient and rapid method of safety evaluation and countermeasure identification via traffic encounters, specifically traffic conflicts that are considered useful surrogates of crashes. Recent research-delivered methods for estimating crash frequencies based on these events were observed in the field. In this project we developed a method for observing traffic encounters with two LiDAR-based traffic monitoring units, called TScan, which were recently developed in JTRP-funded projects SPR-3831 and SPR-4102. The TScan units were deployed in the field for several hours to collect data at selected intersections. These large data sets were used to improve object detection and tracking algorithms in order to better assist in detecting traffic encounters and conflicts. Consequently, the software of the TScan trailer-based units was improved and the results generated with the upgraded system include a list of potential encounters for further analysis. We developed an engineering application for analyzing the trajectories of vehicles involved in the pre-selected encounters to identify final traffic encounters and conflicts. Another module of the engineering application visualized the traffic encounters and conflicts to inspect the spatial patterns of these events and to estimate the number of crashes for the observation period. Furthermore, a significant modeling effort resulted in a method of producing factors that expand the conflict-based crash estimates in short observation periods to an entire year. This report provides guidelines for traffic encounters and conflicts, the user manuals for setting up and operating the TScan research unit. and manuals for the engineering applications mentioned above
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