YOLO-V3 based real-time drone detection algorithm

Multimedia Tools and Applications - Drones are currently being used in a wide range of useful tasks that are too dangerous or/and expensive to be performed by humans. However, this is increasingly...     

Spectroscopy for the Analysis of Nanoporous Silicon Gas and Humidity Sensors

In this work, a Raman spectroscopic study of nanoporous silicon sensor samples demonstrated its use as a method of gauging the sensor potential via quantitative data it provides on the sensor nanostructure dimensions. This special property of the Raman spectroscopy technique also showed its potential to determine mechanical stability of the samples over 3 months. This work also shows that the Raman spectroscopy technique is sensitive to step changes in relative humidity in all the sensor samples via its measurement of the strain-free crystalline silicon (c-Si) Raman peak. Since the Raman technique is non-destructive and senses remotely on the fragile nanoporous sensor samples it will be the ideal replacement of the presently used electrical capacitance techniques as the primary determination of relative humidity.     

Synthesis,characterization, bactericidal activity,and mechanical properties of hydroxyapatite nano powders impregnated with silver and zinc oxide nanoparticles (Ag-ZnO-Hap)

Hydroxyapatite (Hap) doped or embedded with silver has shown improved bactericidal properties, and its mechanical properties were greatly improved by doping or impregnating Hap with metals such as Magnesium or Zinc, or by impregnating Hap with metal oxides such as MgO, or ZnO. This work describes the preparation of Ag-ZnO-Hap nanocomposites with 4 different Ag-ZnO–Ca mole ratios. XRD, FTIR, SEM, and TEM analysis of all prepared materials identified Hap as the only crystalline phase present in all samples exhibiting a uniform rod-like morphology with particles in the 20–40 nm size range. Microwave Plasma-Atomic Emission Spectroscopy confirmed the presence of zinc and silver in all embedded Hap samples. The antibacterial activity was tested against two different strains; Escherichia coli (E. coli (MV10Nal), and Gram-negative Aggregatibacter actinomycetemcomitans (A.a). The mechanical testing consisted of evaluating breaking force, work of fracture, and brittleness/ductility of Hap and Ag/ZnO/Hap composites. Our study clearly shows that reinforcing Hap with silver and zinc oxide yields superior bactericidal and mechanical properties.     

Macroporous rubber gels as reusable sorbents for the removal of oil from surface waters

Macroporous organogels were prepared by solution crosslinking various rubbers in benzene at ?18 °C. Butyl rubber (PIB), cis-polybutadiene (CBR) and styrene–butadiene rubber (SBR) were used as the rubber components, while sulfur monochloride was the crosslinker in the gel preparation. The organogel networks consist of large pores of 10¹–10² μm in size caused by the benzene crystals acting as a template during gelation. The networks formed by CBR and SBR showed an aligned porous structure consisting of regular pores, whereas those derived from PIB had irregular pores with a broad pore size distribution due to the phase separation of PIB chains at low temperatures. All organogels were very tough and could be completely compressed without any crack development. Sorption tests showed that the organogels were efficient at removing crude oil, gasoline, diesel, fuel oil and olive oil. The organogels are reusable once they are squeezed, leading to continuous sorption capacities of CBR or SBR gels for crude oil and olive oil of 33–38 g/g and 24–27 g/g, respectively. These sorption capacities are two to three times the capacity of the gels derived from PIB.     

Temperature and alkaline hydroxide treatment effects on hydrogen sorption characteristics of multi-walled carbon nanotube–graphite mixture

Temperature and alkaline hydroxide treatment effects on the surface area and pore structure of the cathode deposit multi-walled carbon nanotube (MWCNT)–graphite mixture were investigated in a temperature range of 600–800 °C. Hydrogen sorption properties of the MWCNT–graphite mixture samples were studied by varying the alkaline hydroxide-activation temperature. Pore characterization of modified MWCNT–graphite mixture was performed with the observation of adsorption–desorption isotherms of N₂ at 77 K. Hydrogen sorption of the non-treated and treated MWCNT–graphite mixture was carried out using a volumetric apparatus at 77 K. The highest surface area of the sample was obtained as 275 m² g^?1 by treatments with KOH at 600 °C. The increase in the specific surface area of MWCNT–graphite sample mixture was about 13 times. The maximum amount of hydrogen adsorbed on the MWCNT–graphite sample mixture was found as 0.75 and 0.54 wt.% by chemical treatments with KOH at 600 °C and NaOH at 700 °C, respectively whereas it was 0.01 wt.% for the original sample. The hydrogen sorption capacity was enhanced considerably by KOH treatments at 600 °C.     

An improved lumped element nonlinear circuit model for a circular CMUT cell

This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell. The force model is rederived so that the energy and power is preserved in the equivalent circuit model. The model is able to predict the entire behavior of CMUT until the membrane touches the substrate. Many intrinsic properties of the CMUT cell, such as the collapse condition, collapse voltage, the voltage-displacement interrelation and the force equilibrium before and after collapse voltage in the presence of external static force, are obtained as a direct consequence of the model. The small signal equivalent circuit for any bias condition is obtained from the large signal model. The model can be implemented in circuit simulation tools and model predictions are in excellent agreement with finite element method simulations.     

Use of ozone for the preparation of functional silk fibroin-based biomaterial loaded with bioactive compounds for biomedical applications

Silk fibroin (SF) can be used for the preparation of porous functional biomaterials due to its biocompatibility, biodegradability, and minimal in?ammatory reactions. High porosity and homogenous interconnected pore structure is a challenge for the preparation of porous biomaterials. Porous SF foam materials can be formed by bubbling inert gases through aqueous solutions and subsequent freeze drying process. In this study, SF foam structures were prepared by first purging ozone gas and then freeze drying of this ozone-treated aqueous SF solution. Resulting porous materials were efficiently loaded with plant extract for the preparation of functional biomaterials having antimicrobial properties. The interactions of SF with ozone led to chemical modifications that improved both foaming and hydrophobic properties. Intensive ozone treatment caused the crystallinity degree of untreated SF to decrease from 48% to 42%. Ozone treatment also resulted in a significant reduction in surface tyrosine content from 55% to 43%. The use of ozone gas for the preparation of SF foam material enhanced the adsorption capacity of phenolic compounds. The enhancement in the adsorption of phenolic compounds on SF foam structure can be attributed to the oxidation-dependent increase in hydrophobicity.     

High efficiency TiO2/MWCNT based anode electrodes for Li‐ion batteries

Freestanding multiwalled carbon nanotube and titanium (IV) oxide anode paper was prepared by vacuum filtration of multiwall carbon nanotubes/TiO₂ hybrid material, which was synthesized by the radio frequency magnetron sputtering techniques. Field emission scanning electron microscopy images revealed that the carbon nanotubes (CNTs) form a three‐dimensional nanoporous network, in which ultrafine TiO₂ crystals that had crystallite sizes ranging between 7.14 nm and 12.21 nm were distributed homogenously over the surfaces of multiwalled CNT bundles. Electrochemical measurements demonstrated that the prepared powder by using 200 W radio frequency power had excellent cyclic retention, with the high specific capacity of 230 rnAh g^?l up to 50 cycles at a current density. Freestanding papers composed of multiwall carbon nanotubes could act as a flexible mechanical support for strain release offering an efficient electrically conducting channel ,whereas the TiO₂ provides the high capacity. The electrochemical response is maintained in the initial and further cycling process. Such capabilities demonstrate that this model hold great promise for applications requiring flexible and bendable Li‐ion batteries. Copyright © 2014 John Wiley & Sons, Ltd.