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We report on the photosensitization of photorefractive (PR) polymeric composites through the inclusion of multiwalled and singlewalled carbon nanotubes (CNTs), respectively, having poly(N-vinyl carbazole) (PVK) grafted to their surfaces. The PR nature of the holographic gratings was confirmed via the asymmetric exchange of energy in a two-beam-coupling (TBC) geometry, yielding TBC gain coefficients approaching 80 cm-1. In addition, in degenerate-four-wave-mixing experiments the prepared composites exhibited diffraction efficiencies as high as 60% and overmodulation voltages as low as ∼40 V/μm. These notable figures of merit indicate that the grafting of the PVK polymer to the various CNTs results in enhanced PR performance. The mechanism responsible for this enhancement in PR performance is investigated using a variety of experimental techniques. [ABSTRACT FROM AUTHOR]

Cubic pyrochlore Bi1.5Zn1.0Nb1.5O7 thin films were deposited by pulsed laser ablation on Pt(200)/SiO2/Si at 500, 550, 600, and 650 °C. The thin films with (222) preferred orientation were found to grow at 650 °C with better crystallinity which was established by the lowest full-width half maxima of ∼0.38. The dielectric response of the thin films grown at 650 °C have been characterized within a temperature range of 270-650 K and a frequency window of 0.1-100 kHz. The dielectric dispersion in the thin films shows a Maxwell-Wagner type relaxation with two different kinds of response confirmed by temperature dependent Nyquist plots. The ac conduction of the films showed a varied behavior in two different frequency regions. The power law exponent values of more than 1 at high frequency are explained by a jump-relaxation-model. The possibility of grain boundary related large polaronic hopping, due to two different power law exponents and transformation of double to single response in Nyquist plots at high temperature, has been excluded. The 'attempt jump frequency' obtained from temperature dependent tangent loss and real part of dielectric constants, has been found to lie in the range of their lattice vibronic frequencies (1012-1013 Hz). The activation energy arising from a large polaronic hopping due to trapped charge at low frequency region has been calculated from the ac conduction behavior. The range of activation energies (0.26-0.59 eV) suggests that the polaronic hopping at low frequency is mostly due to oxygen vacancies. [ABSTRACT FROM AUTHOR]

When radiation of sufficiently high energy is incident on the surface of a semiconductor photocathode, electrons are excited from the valence band to the conduction band and these may contribute to the photocurrent. The photocurrent in a single-layer cathode is found to be small, because of collisions within the cathode material, the electron affinity condition, etc. It is observed that when a thin layer of n-type cesium antimonide (Cs[sub 3]Sb) is deposited over a p-type layer of sodium potassium antimonide (Na[sub 2]KSb), there occurs a sharp rise in the photocurrent. The causes for the dramatic increase in the photocurrent obtainable from a sodium potassium antimonide cathode, by depositing a thin layer of cesium antimonide are analyzed in this article. It has been shown that the interface between sodium potassium antimonide and cesium antimonide can result in lowering of the electron affinity to a level below the bottom of the conduction band of sodium potassium antimonide. The drift field that arises at the heterointerface enables the electrons to reach the surface, leading to the emission of almost all the photogenerated electrons within the cathode. The processes involved in photoemission from such a double-layer cathode are examined from a theoretical point of view. The spectral response of the two-layer cathode is also found to be better than that of a single-layer cathode. [ABSTRACT FROM AUTHOR]

Abstract In the present work, n-butyl levulinate is synthesized by esterification of levulinic acid (LA) with n-butanol using Brønsted acidic ionic liquid [MIM][HSO 4 ] as a catalyst in a solvent free condition. The prepared IL was characterized by FT-IR, 13C‐NMR and 1H–NMR. For optimization study, central composite design (CCD) method was employed. Design of experiments and statistical analysis is performed using Design Expert 11 software. The highest yield 89.6% and selectivity 98.1% of n-butyl levulinate were achieved at 90 °C. Biphasic layers of product and IL were observed resulting in self-separation of product. Effects of changes in variable parameters on conversion like LA: n-butanol molar ratio, LA:IL molar ratio and temperature were studied. Arrhenius plot was obtained and Activation energy (E a) was calculated as 53.16 KJ/mol. Substrate study was performed on sec-, iso-, and tert-butanol and 1-Pentanol and n-Hexanol giving high yield and selectivity of corresponding levulinate esters. Catalyst was reused five times without significant decrease in yield. Graphical abstract The present work reports esterification of biomass derived Levulinic acid to synthesis n-butyl levulinate using Brønsted acidic ionic liquid (BAIL), 1-Methyl imidazolium hydrogen sulphate [MIM][HSO 4 ] as a catalyst. The conventional conc. sulphuric acid gives disadvantages like harsh reaction conditions, generation of by-products, additional solvents for product extraction and poor reusability. Herein, we synthesized imidazole based ionic liquid using sulphuric acid which incorporates hydrogen sulphate as an anion. The synthesized ionic liquid is safer to handle and store. It acts as a green homogenous catalyst for esterification at mild reaction conditions and at solvent free system. Insolubility of product ester and ionic liquid allowed self-separation of product from reaction mixture. 98.1% selectivity and yield of 98.1% were achieved. The ionic liquid was reused up to five times without significant loss in catalytic activity. Furthermore, some more Levulinate esters were also synthesized successfully using same IL. Unlabelled Image Highlights • Brønsted acidic ionic liquid [MIM][HSO 4 ] is synthesized and characterized. • Time and cost effective preparation of ionic liquid • High catalytic performance of the synthesized ionic liquid in esterification • Phase separation of ionic liquid and product levulinate ester • Low activation energy of 53.16 KJ/mol [ABSTRACT FROM AUTHOR]

Transport is almost entirely powered by internal combustion engines (ICEs) burning petroleum-derived liquid fuels and the global demand for transport energy is large and is increasing. Available battery capacity will have to increase by several hundred fold for even light duty vehicles (LDVs), which account for less than half of the global transport energy demand, to be run on electricity alone. However the greenhouse gas (GHG) impact of battery electric vehicles (BEVs) would be worse than that of conventional vehicles if electricity generation and the energy used for battery production are not sufficiently decarbonized. If coal continues to be a part of the energy mix, as it will in China and India, and if power generation is near urban centers, even local urban air quality in terms of particulates, nitrogen oxides and sulfur dioxide would get worse. The human toxicity impacts associated with the mining of metals needed for batteries are very serious and will have to be addressed. Large prior investments in charging infrastructure and electricity generation will be needed for widespread forced adoption of BEVs to occur. There will be additional costs in the short term associated with various subsidies required to promote such a change and in the longer term, the loss of revenue from fuel taxes which contribute significantly to public finances in most countries. ICEs will continue to power transport, particularly commercial transport, to a large extent for decades to come and will continue to improve. There will also be a role for low-carbon and other alternative fuels where they make sense. However such alternatives also start from a low base and face constraints on rapid and unlimited growth so that they are unlikely to make up much more than 10% of the total transport energy demand by 2040. As the energy system is decarbonized and battery technology improves there will be an increasing role for BEVs and hydrogen which could replace liquid hydrocarbons in transport and the required infrastructure will evolve. Meanwhile, there will certainly be increasing electrification, particularly of LDVs in the form of hybridization to improve ICEs. [ABSTRACT FROM AUTHOR]

Patterns of submicron Co islands in conjunction with a uniform, static, or rotating magnetic field are used to demonstrate the possibility of assembling 100–300 nm nonmagnetic latex beads in designated locations and manipulating their movements on surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Previous work has demonstrated that single-cylinder CI engines, with relatively modest changes to operating conditions over a wide operating range, can be run with both very low NOx and low smoke as well as at high efficiency on fuels with high resistance to autoignition such as gasoline. The purpose of this work was to run a multi-cylinder engine without any major changes to the engine system on a gasoline fuel at constant fuel demand to get better understanding of the possible practical advantages and challenges. A 2.7dm3 Euro IV V6 diesel engine was run on a European standard diesel fuel of 54 CN (Cetane Number) according to the engine map at 1000rpm and 1500rpm at different loads. At the same speeds and loads, it was also run on a 84 RON gasoline but with different injection strategies and operating parameters, such as EGR levels. With gasoline, NOx levels comparable to the diesel map point could be obtained but at lower EGR rates, at lower injection pressures and lower brake specific fuel consumption and with extremely low smoke; however the CO and HC emissions were higher. The engine could not be run at high speeds or at loads greater than 12bar IMEP on gasoline because, without introducing modifications, the fuel overheated and gave rise to vapour-lock problems. Also at high loads, in order to limit NOx emissions, high EGR rates were required but the CO levels were excessive, because the particular turbocharger could not deliver adequate intake pressure at such conditions and hence the intake oxygen levels were too low. Thus further modifications to the fuel system and an alternative turbocharger would be needed to extend the operating range on gasoline. There appears to be potential for simplifying future CI engines e.g. by using lower injection pressures and replacing lean NOx after-treatment by CO and HC control by using gasoline-like fuels. [Copyright &y& Elsevier]

Non-thermal dielectric barrier discharge (DBD) plasma is now being widely developed for various clinical applications1,2 but the mechanisms of interaction of such plasmas with mammalian cells are still not well understood. It is known that DBD plasma produces ozone and it is possible that the effects of plasma may be mediated purely by ozone. Although typically requiring much higher treatment time than the typical plasma treatment times reported here, ozonation is, in fact, widely employed to kill microorganisms in water and is also used for wound healing. It has been shown earlier that plasma treatment of mammalian cells submerged in a shallow layer of culture medium can result in dose dependent DNA damage. We wanted to understand the role of ozone in mediating the interaction of non-thermal plasma DBD plasma with mammalian cells. Upon comparing plasma treatment of mammalian breast epithelial cells with ozone treatment we found that ozone treatment is qualitatively different from non-thermal DBD plasma and in fact does not play a role in mediating the observed effects of plasma on mammalian cells. [ABSTRACT FROM AUTHOR]

Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces no heat, so its effects can be selective. In order to exploit the potential for clinical applications, including wound healing, sterilization, blood coagulation, and cancer treatment, a mechanistic understanding of the interaction of non-thermal plasma with living tissues is required. Using mammalian cells in culture, it is shown here that non-thermal plasma created by dielectric barrier discharge (DBD) has dose-dependent effects that range from increasing cell proliferation to inducing apoptosis. It is also shown that these effects are primarily due to formation of intracellular reactive oxygen species (ROS). We have utilized γ-H2AX to detect DNA damage induced by non-thermal plasma and found that it is initiated by production of active neutral species that most likely induce formation of organic peroxides in cell medium. Phosphorylation of H2AX following non-thermal plasma treatment is ATR dependent and ATM independent, suggesting that plasma treatment may lead to replication arrest or formation of single-stranded DNA breaks; however, plasma does not lead to formation of bulky adducts/thymine dimers. [ABSTRACT FROM AUTHOR]

Much of the technology in advanced diesel engines, such as high injection pressures, is aimed at overcoming the short ignition delay of conventional diesel fuels to promote premixed combustion in order to reduce NOxand smoke. Previous work in a 2 1 singlecylinder diesel engine with a compression ratio of 14 has demonstrated that gasoline fuel, because of its high ignition delay, is very beneficial for premixed compression ignition compared with a conventional diesel fuel. We have now done similar studies in a smaller-0.537 ∫-single-cylinder diesel engine with a compression ratio of 15.8. The engine was run on three fuels of very different auto-ignition quality-a typical European diesel fuel with a cetane number (CN) of 56, a typical European gasoline of 95 RON and 85 MON with an estimated CN of 16 and another gasoline of 84 RON and 78 MON (estimated CN of 21). The previous results with gasoline were obtained only at 1200 rpm-here we compare the fuels also at 2000 rpm and 3000 rpm. At 1200 rpm, at low loads (∼4 bars indicated mean effective pressure (IMEP)) when smoke is negligible, NOxlevels below 0.4 g/kWh can be easily attained with gasoline without using exhaust gas recirculation (EGR), while this is not possible with the 56 CN European diesel. At these loads, the maximum pressure-rise rate is also significantly lower for gasoline. At 2000 rpm, with 2 bars absolute intake pressure, NOxcan be reduced below 0.4 g/kW h with negligible smoke (FSN<0.1) with gasoline between 10 bars and 12 bars IMEP using sufficient EGR, while this is not possible with the diesel fuel. At 3000 rpm, with the intake pressure at 2.4 bars absolute, NOxof 0.4 g/kW h with negligible smoke was attainable with gasoline at 13 bars IMEP Hydrocarbon and CO emissions are higher for gasoline and will require after-treatment. High peak heat release rates can be alleviated using multiple injections. Large amounts of gasoline, unlike diesel, can be injected very early in the cycle without causing heat release during the compression stroke and this enables the heat release profile to be shaped. [ABSTRACT FROM AUTHOR]

Abstract: The functional relationship of autoignition delay time with temperature and pressure is employed to derive the propagation velocities of autoignitive reaction fronts for particular reactivity gradients, once autoignition has been initiated. In the present study of a variety of premixtures, with different functional relationships, such gradients comprise fixed initial temperature gradients. The smaller is the ratio of the acoustic speed through the mixture to the localised velocity of the autoignitive front, the greater are the amplitude and frequency of the induced pressure wave. This might lead to damaging engine knock. At higher values of the ratio, the autoignition can be benign with only small over-pressures. This approach to the effects of autoignition is confirmed by its application to a variety of experimental studies involving: [(i)] Imposed temperature gradients in a rapid compression and expansion machine. [(ii)] Onset of knock in an engine with advancing spark timing. [(iii)] Development of autoignition at a single hot spot in an engine. [(iv)] Autoignition fronts initiated by several hot spots. There is much diversity in the effects that can be produced by different fuels in different ranges of temperature and pressure. Higher values of autoignitive propagation speeds lead to increasingly severe engine knock. Such effects cannot always be predicted from the Research and Motor octane numbers. [Copyright &y& Elsevier]

Measured flash points of blends of a commercial diesel and a commercial gasoline are presented along with data on volatility characteristics. The flash point falls very rapidly as the concentration of gasoline is increased and reaches −40 °C at a gasoline concentration of 16% by volume. This suggests that blends with gasoline concentrations of greater than 50% by volume, which are of interest in the development of gasoline compression ignition (GCI) engines, should be safe to use in vehicles because they will be very similar to gasoline which has a flash point of −45 °C. [ABSTRACT FROM AUTHOR]

Mechanisms of blood coagulation by direct contact of nonthermal atmospheric pressure dielectric barrier discharge (DBD) plasma are investigated. This paper shows that no significant changes occur in the pH or Ca2+ concentration of blood during discharge treatment. Thermal effects and electric field effects are also shown to be negligible. Investigating the hypothesis that the discharge treatment acts directly on blood protein factors involved in coagulation, we demonstrate aggregation of fibrinogen, an important coagulation factor, with no effect on albumin. We conclude that direct DBD treatment triggers selective natural mechanisms of blood coagulation. [ABSTRACT FROM AUTHOR]

A wideband diplexer is designed and developed in suspended substrate medium using wide-bandpass filters of 10–14 GHz and 14–18 GHz. Tight coupling between resonators is achieved by etching the resonators on the top and bottom layers of the substrate. The diplexer is designed by combining these filters on a common transformer. Each filter is channelised to avoid waveguide modes. Suspended substrate striplines (SSSs) are characterized using the Finite-Difference Method (FDM). The theoretical and measured results of the diplexer are presented. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. [ABSTRACT FROM AUTHOR]

Investigates the external hydrodynamic loading exerted by steady incident flows on submarine pipelines. Interactions between pipeline and seabed; Piggyback configurations; Importance of direction of transverse lift force; Characteristics of both single pipeline and piggyback configurations; Factors that may increase likelihood of generating free-spans along the pipeline.

Desmoid fibromatosis is a rare tumor affecting bone. This tumor histologically and biologically mimics the extra-abdominal desmoid tumor of soft tissue. This is locally infiltrative and aggressive in nature. The reported incidence of such cases is around 2–4 per million population which accounts for 0.03% of all neoplasms. In maxillofacial region, incidence is less than 3% of all cases. Treatment of such tumors is surgical excision and chances of recurrence are more. We hereby report a case of a 23-year-old female patient with desmoid fibromatosis in the mandibular posterior region. [ABSTRACT FROM AUTHOR]

Petroleum-derived gasoline is currently the most widely used fuel for transportation propulsion. The design and operation of gasoline fuels is governed by specific physical and chemical kinetic fuel properties. These must be thoroughly understood in order to improve sustainable gasoline fuel technologies in the face of economical, technological, and societal challenges. For this reason, surrogate mixtures are formulated to emulate the thermophysical, thermochemical, and chemical kinetic properties of the real fuel, so that fundamental experiments and predictive simulations can be conducted. Early studies on gasoline combustion typically adopted single component or binary mixtures (n-heptane/isooctane) as surrogates. However, the last decade has seen rapid progress in the formulation and utilization of ternary mixtures (n-heptane/isooctane/toluene), as well as multicomponent mixtures that span the entire carbon number range of gasoline fuels (C 4 –C 10 ). The increased use of oxygenated fuels (ethanol, butanol, MTBE, etc.) as blending components/additives has also motivated studies on their addition to gasoline fuels. This comprehensive review presents the available experimental and chemical kinetic studies which have been performed to better understand the combustion properties of gasoline fuels and their surrogates. Focus is on the development and use of surrogate fuels that emulate real fuel properties governing the design and operation of engines. A detailed analysis is presented for the various classes of compounds used in formulating gasoline surrogate fuels, including n-paraffins, isoparaffins, olefins, naphthenes, and aromatics. Chemical kinetic models for individual molecules and mixtures of molecules to emulate gasoline surrogate fuels are presented. Despite the recent progress in gasoline surrogate fuel combustion research, there are still major gaps remaining; these are critically discussed, as well as their implications on fuel formulation and engine design. [ABSTRACT FROM AUTHOR]

Abstract: Thermal plasma is a valued tool in surgery for its coagulative and ablative properties. We suggested through in vitro studies that nonthermal plasma can sterilize tissues, inactive pathogens, promote coagulation, and potentiate wound healing. The present research was undertaken to study acute toxicity in porcine skin tissues. We demonstrate that floating electrode-discharge barrier discharge (FE-DBD) nonthermal plasma is electrically safe to apply to living organisms for short periods. We investigated the effects of FE-DBD plasma on Yorkshire pigs on intact and wounded skin immediately after treatment or 24h posttreatment. Macroscopic or microscopic histological changes were identified using histological and immunohistochemical techniques. The changes were classified into four groups for intact skin: normal features, minimal changes or congestive changes, epidermal layer damage, and full burn and into three groups for wounded skin: normal, clot or scab, and full burn-like features. Immunohistochemical staining for laminin layer integrity showed compromise over time. A marker for double-stranded DNA breaks, γ-H2AX, increased over plasma-exposure time. These findings identified a threshold for plasma exposure of up to 900s at low power and <120s at high power. Nonthermal FE-DBD plasma can be considered safe for future studies of external use under these threshold conditions for evaluation of sterilization, coagulation, and wound healing. [Copyright &y& Elsevier]

Higher fuel anti-knock quality will be required as spark ignition engines are designed for higher efficiency in the future. This paper introduces a new high-octane gasoline blending component made from low value mixed butenes using a new process. The component named SuperButol™ is mainly a mixture of butanol isomers (∼93%) with small amounts of diisobutylenes (∼5%) and di- sec -butyl ether (∼2%). The manufacturing process is described in brief and the results of blending this product on gasoline properties and comparison with other high-octane components such as MTBE and ethanol are presented. SuperButol™ has slightly lower blending RON compared to MTBE but has lower blending vapor pressure and higher energy content compared to ethanol. SuperButol™ has insignificant effect on key gasoline specifications, namely, potential and actual gum, oxidation stability, intake valve deposits, port fuel injector fouling, haze formation and water extractability performance. Therefore, it is considered to be a viable and affordable gasoline component, which can help to meet future demands for high-octane gasoline. In addition, the process helps to optimize refinery operations by valorizing low-value products. [ABSTRACT FROM AUTHOR]

A methodology for estimating the octane index (OI), the research octane number (RON) and the motor octane number (MON) using ignition delay times from a constant volume combustion chamber with liquid fuel injection is proposed by adopting an ignition quality tester. A baseline data of ignition delay times were determined using an ignition quality tester at a charge pressure of 21.3 bar between 770 and 850 K and an equivalence ratio of 0.7 for various primary reference fuels (PRFs, mixtures of iso-octane and n -heptane). Our methodology was developed using ignition delay times for toluene reference fuels (mixtures of toluene and n -heptane). A correlation between the OI and the ignition delay time at the initial charge temperature enabled the OI of non-PRFs to be predicted at specified temperatures. The methodology was validated using ignition delay times for toluene primary reference fuels (ternary mixtures of toluene, iso-octane, and n -heptane), fuels for advanced combustion engines (FACE) gasolines, and certification gasolines. Using this methodology, the RON, the MON, and the octane sensitivity were estimated in agreement with values obtained from standard test methods. A correlation between derived cetane number and RON is also provided. [ABSTRACT FROM AUTHOR]

ABSTRACT In this letter, a new design of a band select ultra wide band (UWB) unequal power splitter suitable for broadband communication systems was presented. To obtain band select characteristics, the proposed structure used broadside coupled lines. The quarter wave transformer in the conventional Wilkinson power splitter was replaced by offset broadside coupled lines to achieve broadband operation in this letter. The broadside coupled line configuration was achieved between the transmission lines in the top layer and a floating conductor in the defected ground plane of the microstrip medium. The advantage of this type of power splitter was that it could reject the out of band frequency signals. The proposed two way UWB unequal power splitter was designed using microstrip medium with defected ground structure for a wide range of frequencies between 3.1 and 8 GHz. Experimental results of the designed unequal power splitter (10 and 0.5dB) have been verified against the results full wave simulations and the results were in good agreement. The amplitude variation over the frequency band was within ±0.3 dB. The isolation between the output ports was more than 19 dB. Size of the realized power splitter was 36 mm × 40 mm × 0.78 mm. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1563-1566, 2016 [ABSTRACT FROM AUTHOR]

Gasoline compression ignition (GCI) engines could be more efficient than most advanced SI engines while running on lower octane fuel. GCI engines may utilize a mixture of different fuels and fuel components such as gasoline and diesel or diesel and naphtha. The risks and hazards associated with such mixtures must be studied to ensure safe fuel storage, shipping and dispensing. In this work, flash point and vapor pressure measurements of different binary multi-component hydrocarbon mixtures are presented along with calculated lower and upper flammability limits. An equation has been developed to correlate flash point with other fuel properties. The flash point of a mixture approaches the flash point of the more volatile component, falling rapidly in some cases, as the more volatile component concentration increases. Vapor pressure is inversely related to flash point for a given mixture. Diesel/light straight run naphtha mixtures and diesel/gasoline mixtures exhibit similar flash point versus vapor pressure trends. Flammability limits were calculated using Le Chatelier’s Mixing Rule and modified Burgess–Wheeler Law. Hydrocarbon mixtures have similar lower and upper flammability limits over a range of temperatures. The vapor pressure of fuels and fuel blends has been used to determine the safe operating region as a function of blending formula and temperature. This work demonstrates that normal butane can be used to formulate blends of gasoline and naphtha with diesel, which are safe to handle and meet seasonal vapor pressure requirements. [ABSTRACT FROM AUTHOR]

A detailed chemistry and pollutant formation model combined with an advanced combustion simulation tool DI-SRM (direct injection stochastic reactor model) and time based mixing model are used to simulate the in-cylinder physico-chemical processes such as compression, heat transfer, charge stratification/mixing and gas phase chemistry in a single cylinder diesel engine run in premixed compression ignition (PCI) mode. These models were used to simulate the combustion of different model fuels (n-heptane, PRF 84 and TRF 82, a toluene isooctane and n-heptane blend) and full boiling range unleaded gasoline (ULG 84 and ULG 91), using the same 3 components (n-heptane, iso-octane and toluene) surrogate model for all five fuels. Soot was simulated using the method of moments, a Probability Density Function (PDF) based model and the other pollutants such as NOx, CO and unburned hydrocarbon (UHC) are estimated through the chemical mechanism model used in this study. The blending of each surrogate fuel was based on the auto-ignition characteristics of the fuel used in the experimental work. The model performed well, in terms of in-cylinder pressure, heat release rate, combustion phasing parameters and pollutant emissions. Phi-T maps were used to gain further insight into both the simulated and experimental data. These maps are used to better understand the processes that take place during the combustion event under PCI combustion mode such as mixing, fuel auto-ignition characteristics and the effect of RON and aromatic content on PM emissions. [ABSTRACT FROM AUTHOR]

Approximate closed-form expressions for the propagation characteristics of a microstrip line with a symmetrical aperture in its ground plane are reported in this article. Well-known expressions for the characteristic impedance of a regular microstrip line have been modified to incorporate the effect of this aperture. The accuracy of these expressions for various values of substrate thickness, permittivity and line width has been studied in detail by fullwave simulations. This has been further verified by measurements. These expressions are easier to compute and find immense use in the design of broadband filters, tight couplers, power dividers, transformers, delay lines, and matching circuits. A broadband filter with aperture in ground plane is demonstrated in this article. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. [ABSTRACT FROM AUTHOR]

Design of an Ultra Wide Band (UWB) filter over 3.1 GHz to 10.6 GHz using broad side coupled and spur lines in microstrip medium suitable for UWB communications has been presented in this paper. Parameters of broad side coupled lines have been appropriately chosen to achieve ultra wide band response. Spur lines have been incorporated at the input and output feed lines of the filter to improve the stop band rejection characteristics of the filter. Filter has been analyzed based on circuit models and full wave simulations. Experimental results of the filter designed using the proposed structure has been verified against the results obtained from circuit models and full wave simulations. The results match satisfactorily. Stop band rejection of better than 20 dB was obtained over the frequencies of 13 GHz to 18.2 GHz. Overall size of the filter is 40 × 18 × 0.787 mm3. [ABSTRACT FROM AUTHOR]

Abstract: A semidetailed mechanism (137 species and 633 reactions) and new experiments in a homogeneous charge compression ignition (HCCI) engine on the autoignition of toluene reference fuels are presented. Skeletal mechanisms for isooctane and n-heptane were added to a detailed toluene submechanism. The model shows generally good agreement with ignition delay times measured in a shock tube and a rapid compression machine and is sensitive to changes in temperature, pressure, and mixture strength. The addition of reactions involving the formation and destruction of benzylperoxide radical was crucial to modeling toluene shock tube data. Laminar burning velocities for benzene and toluene were well predicted by the model after some revision of the high-temperature chemistry. Moreover, laminar burning velocities of a real gasoline at 353 and 500 K could be predicted by the model using a toluene reference fuel as a surrogate. The model also captures the experimentally observed differences in combustion phasing of toluene/n-heptane mixtures, compared to a primary reference fuel of the same research octane number, in HCCI engines as the intake pressure and temperature are changed. For high intake pressures and low intake temperatures, a sensitivity analysis at the moment of maximum heat release rate shows that the consumption of phenoxy radicals is rate-limiting when a toluene/n-heptane fuel is used, which makes this fuel more resistant to autoignition than the primary reference fuel. Typical CPU times encountered in zero-dimensional calculations were on the order of seconds and minutes in laminar flame speed calculations. Cross reactions between benzylperoxy radicals and n-heptane improved the model predictions of shock tube experiments for and temperatures lower than 800 K for an n-heptane/toluene fuel mixture, but cross reactions had no influence on HCCI simulations. [Copyright &y& Elsevier]

This paper gives the closed form expressions for the resonator length and spurious frequencies of a quad-section stepped impedance resonator (QSIR) in terms of impedance ratios. An experimental filter using QSIRs at 2.4 GHz has been designed and tested to verify the analysis. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 649–652, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23158 [ABSTRACT FROM AUTHOR]

This paper reports the design of a compact branch line coupler based on defected ground structure (DGS) in microstrip medium. Unit cell's (of DGS) equivalent circuit has been used to evaluate the performance of coupler. Based on this approach, a compact coupler has been realized at 2.4 GHz yielding a size reduction of 33% over the conventional coupler. [ABSTRACT FROM AUTHOR]

Design of an ultra wide band (UWB) filter using tightly coupled lines in micro strip medium suitable for UWB communications has been presented in this paper. Coupled lines with centrally loaded open circuited stubs have been appropriately chosen to locate the two attenuation poles, close to either side of the desired pass band. Experimental results of a 3.1–5.3 GHz filter designed using the present method have been verified against the results obtained from circuit model. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 436–439, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22166 [ABSTRACT FROM AUTHOR]

A compact CPW fed planar inverted conical antenna with coplanar ground embedding the radiator has been studied with regard to its suitability for the UWB transceivers operating over 3.1–10.6 GHz. Performance of planar inverted conical antenna embedded in a similar shaped ground plane is compared with the planar inverted conical antenna having ground in plane with the radiator. Results from the simulations have been validated through experimentations. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2465–2468, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21980 [ABSTRACT FROM AUTHOR]

This article presents realization of low loss, wide stop-band suspended substrate stripline (SSS) wideband pass filters using interdigital and stepped-impedance resonators. SSSs have been characterized using the finite-difference method (FDM). The experimental results of the fabricated filters are compared with the theoretical results. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. [ABSTRACT FROM AUTHOR]

The Cantilevers and beams are the very basic structures used in MEMS. This paper describes the use of PSPICE circuit simulator for simulations in 2 domains — Electrical and Thermal. The analogy between heat flow and electrical circuits give us an electrical equivalent circuit that can simulate the thermal heat flow. The steady-state and transient simulations of a heatuator have been done using PSPICE giving thermal time constants of the order of 40 µ-sec. [ABSTRACT FROM AUTHOR]

A simplified method for design and analysis of a direct coupled waveguide iris filter suitable for computer aided design implementation is presented. A curve fit formula for calculating the aperture dimensions of an iris as a function of normalized shunt inductor values is given. The analysis of the entire filter response is calculated using ABCD parameters. Using proposed equations a five section iris filter at X band has been designed and tested. Comparison between measured and theoretical results is shown. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 150–154, 1999 [ABSTRACT FROM AUTHOR]

Using periodically elevated groundplane along the coupled line sections in the lower cavity of suspended substrate stripline (SSS), a parallel-coupled line band-pass filter having suppressed harmonic at 2f0 has been designed. Even and odd mode phase velocities in each coupled line section at 2f0 have been equalised by using the right number of periodic grounding cells with proper dimensions. Based on this equalisation technique, a filter at 2.4 GHz has been designed and fabricated to prove the concept. [ABSTRACT FROM AUTHOR]

This paper presents parametric studies related to equalization of even- and odd-mode phase velocities in coupled suspended substrate striplines (SSSs). An SSS band-pass filter at 2.4 GHz with suppressed 2nd harmonic has been designed using the present phase-velocity equalization technique and experimental results of the filter are discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 600–602, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21419 [ABSTRACT FROM AUTHOR]

Background: Hands are the most common medium for initiation and spread of infection in clinics. Hand hygiene is the simplest and most economic method for reducing the healthcare-associated infections (HCAIs). Aim: The aim of the present study was to compare the efficacy of hand sanitizer, liquid soap, and their combination for reducing the microbial colonies on hands. Materials and methods: The study was a single-blinded randomized controlled trial executed in a dental college on 90 participants, which were randomly assigned into three intervention groups of 30 each. The participants were instructed to contaminate their hands followed by a hand hygiene protocol for the liquid hand-wash group, the alcohol-based hand sanitizer (ABHS) group, and the combination group according to WHO guidelines. The swabs were collected pre- and post-intervention and mean colony-forming units were determined for each group. Results: Median percentage reduction was highest for the combination group (100%), followed by the ABHS group (94.29%) and lowest for the liquid soap (92.31%). This difference in the amount of colony-forming units (CFU) among all the groups was nonsignificant (p = 0.114). Conclusion: The results of the study show that there was no significant difference in hand disinfection potential among hand sanitizer, liquid soap, or their combination. All the three interventions were equally effective with the reduction of total bacterial contamination from participants' hands. [ABSTRACT FROM AUTHOR]

InN quantum dots (QDs) were grown on Si (111) by epitaxial Stranski-Krastanow growth mode using plasma-assisted molecular beam epitaxy. Single-crystalline wurtzite structure of InN QDs was verified by the x-ray diffraction and transmission electron microscopy. Scanning tunneling microscopy has been used to probe the structural aspects of QDs. A surface bandgap of InN QDs was estimated from scanning tunneling spectroscopy (STS) I-V curves and found that it is strongly dependent on the size of QDs. The observed size-dependent STS bandgap energy shifts with diameter and height were theoretical explained based on an effective mass approximation with finite-depth square-well potential model. [ABSTRACT FROM AUTHOR]

GaN films were grown on c-plane sapphire by plasma-assisted molecular beam epitaxy (PAMBE). The effect of N/Ga flux ratio on structural, morphological, and optical properties was studied. The dislocation density found to increase with increasing the N/Ga ratio. The surface morphology of the films as seen by scanning electron microscopy shows pits on the surface and found that the pit density on the surface increases with N/Ga ratio. The room temperature photoluminescence study reveals the shift in band-edge emission toward the lower energy with increase in N/Ga ratio. This is believed to arise from the reduction in compressive stress in the films as is evidenced by room temperature Raman study. The transport studied on the Pt/GaN Schottky diodes showed a significant increase in leakage current with an increase in N/Ga ratio and was found to be caused by the increase in pit density as well as increase in dislocation density in the GaN films. [ABSTRACT FROM AUTHOR]

Recently, various high quality factor photonic crystal microcavities have been demonstrated theoretically and experimentally with only one-dimensional periodicity. However, in most cases high-index materials such as silicon were chosen for easily achievable large photonic bandgap and elaborate refractive index modulation or taper structure is required for reducing radiation loss. Here, we present a design of high-Q microcavities in one-dimensional multilayer polystyrene photonic crystal slab structures with a low-index contrast of 1.59:1. Microcavities are introduced by simply decreasing the thickness of layers at the center region to form a double-heterostructure. A resonant mode with a quality factor up to 20 000 is obtained and found to originate from the modal gap confinement by comparing with a Fabry-Perot cavity. The dependence of the maximal quality factor on the cavity length further reveals that the small group velocity of light within the heterostructure cavity contributes significantly to the high-Q. In terms of the high quality factor, ease of fabrication, and large Kerr nonlinearity of polystyrene, our double-heterostructure microcavities will find potential application in realizing all-optical modulation devices. [ABSTRACT FROM AUTHOR]

Ethanol is one of the most desirable fuels for spark-ignition engines. It offers high-octane quality and a latent heat of vaporization that is four times greater than gasoline on a stoichiometric basis. Anhydrous ethanol can also readily be blended into oil-based fuels, thereby enabling improved engine efficiency and reduced greenhouse gas (GHG) emissions. However, the use of ethanol is currently constrained by low yield production processes and a reliance on considerable amounts of arable land to cultivate the most widely utilized feedstocks. These challenges could be addressed if ethanol was instead derived synthetically from petroleum-based feedstocks. This paper presents a comparative well-to-wheel assessment for three different engine-fuel systems that leverage the benefits of ethanol which has been derived synthetically and from the fermentation of biomass. In the baseline case, anhydrous ethanol (99.5% by volume) derived from corn is used to produce a high-octane E30 gasoline (RON 101). The alternative case considers synthetic hydrous ethanol ( ∼ 90% by volume) which is derived from direct hydration of ethene in a crude oil refinery. Hydrous ethanol is immiscible in gasoline, and is therefore utilized as a high-octane fuel for the Octane-on-Demand concept. The same engine-fuel system operated on anhydrous bioethanol is also considered for comparative purposes. Single cylinder engine tests are first used to characterize the specific fuel consumption and CO 2 emissions for the different engine-fuel systems. This data is then used to construct fuel consumption maps to simulate the drive cycle fuel economy of a light-duty vehicle. Finally, the well-to-wheel GHG emissions are computed, with consequent uncertainties assessed using Monte Carlo analysis. The results demonstrate that the well-to-wheel GHG emissions for the three different engine-fuel systems are generally comparable. This is despite the Octane-on-Demand cases offering improved drive cycle fuel economy with respect to the E30 gasoline. These outcomes are shown to be largely insensitive to uncertainties in the upstream fuel production GHG emissions. Overall, this suggests that the use of synthetic ethanol in advanced engine-fuel systems could supplement bioethanol derived from first and second generation feedstocks in the future transport energy mix. [ABSTRACT FROM AUTHOR]

Advanced engine technologies will play a central role in achieving future greenhouse gas (GHG) emissions targets for light-duty vehicles. However, these technologies will place greater emphasis on optimizing the engine and fuel as a synergistic system, since many technologies will require higher octane gasolines to realize their full social and environmental benefits. The most extreme example of a synergistic engine-fuel system is the Octane-on-Demand concept. This technology platform makes use of an oil-derived fuel at low and intermediate loads where the octane requirement of the engine is comparatively low, while a second high octane fuel is introduced at higher loads to suppress knock. This paper presents the first comprehensive study of vehicle fuel economy and well-to-wheel GHG emissions for the Octane-on-Demand concept with respect to a regular grade E10 gasoline (RON 93) and a high octane E30 gasoline (RON 101). Experimental fuel consumption maps are first used to evaluate the drive cycle fuel economy and GHG emissions for a light-duty vehicle equipped with two alternative powertrains. The upstream GHG emissions arising from the production of the fuels are then quantified, with consequent uncertainties assessed using Monte Carlo analysis based on probability distribution functions for critical input parameters. The results demonstrate that the Octane-on-Demand concept used in conjunction with either methanol or ethanol generally provides comparable well-to-wheel GHG emissions to the high octane E30 gasoline, with up to a 10% improvement in the vehicle fuel economy. The use of a non-traditional engine calibration strategy that maximizes the trade-off between thermal efficiency and fuel energy density also enables the amount of high octane fuel required to suppress knock to be reduced significantly. This increases the distance that the vehicle can be driven before the secondary tank requires refueling by a considerable margin, but comes at the expense of marginally higher well-to-wheel GHG emissions than could otherwise be achieved. These findings are shown to be largely insensitive to uncertainties in the upstream fuel production GHG emissions, with the exception of the land use change (LUC) for bioethanol. Overall, this study has implications for the design of engine-fuel systems for future light-duty vehicles. [ABSTRACT FROM AUTHOR]

Gasoline anti-knock quality, defined by the research and motor octane numbers (RON and MON), is important for increasing spark ignition (SI) engine efficiency. Gasoline knock resistance can be increased using a number of blending components. For over two decades, ethanol has become a popular anti-knock blending agent with gasoline fuels due to its production from bio-derived resources. This work explores the oxidation behavior of two oxygenated certification gasoline fuels and the variation of fuel reactivity with molecular composition. Ignition delay times of Haltermann (RON = 91) and Coryton (RON = 97.5) gasolines have been measured in a high-pressure shock tube and in a rapid compression machine at three pressures of 10, 20 and 40 bar, at equivalence ratios of φ  = 0.45, 0.9 and 1.8, and in the temperature range of 650–1250 K. The results indicate that the effects of fuel octane number and fuel composition on ignition characteristics are strongest in the intermediate temperature (negative temperature coefficient) region. To simulate the reactivity of these gasolines, three kinds of surrogates, consisting of three, four and eight components, are proposed and compared with the gasoline ignition delay times. It is shown that more complex surrogate mixtures are needed to emulate the reactivity of gasoline with higher octane sensitivity (S = RON–MON). Detailed kinetic analyses are performed to illustrate the dependence of gasoline ignition delay times on fuel composition and, in particular, on ethanol content. [ABSTRACT FROM AUTHOR]

Higher octane gasoline will be an important factor in enabling future spark-ignition engines to meet increasingly stringent fuel economy and CO 2 emissions requirements. The most effective method to raise the octane ‘floor’ of regular grade gasoline is through the use high octane blend components, such as methanol and ethanol. However, this is often limited by the negative effects associated with energy density, phase separation and cold engine starting. This paper therefore examines the optimal way to leverage the most widely available high octane fuels to improve the performance and environmental impact of light-duty vehicles. A comprehensive set of baseline engine data is first presented for two splash-blended gasolines containing ethanol (E10 and E30). The octane quality of these fuels (RON 93 and 101) has been raised by directly displacing the gasoline blendstock (RON 90) with higher octane ethanol (RON ∼ 109). The two splash-blended gasolines are compared with the Octane-on-Demand concept, which instead leverages only the necessary amount of high octane fuel when the octane requirement of the engine exceeds the level that can be provided by the oil-derived base fuel. The same gasoline blendstock is used in both cases, thus enabling the leveraging effect of the high octane fuels in the Octane-on-Demand configuration to be directly quantified. The results demonstrate that the Octane-on-Demand concept used in conjunction with either methanol or ethanol provides comparable or lower specific CO 2 emissions to the E30 gasoline, with up to a 10% improvement in specific fuel consumption. The use of a non-traditional engine calibration strategy that maximizes the trade-off between thermal efficiency and fuel energy density also enables the amount of high octane fuel required to suppress knock to be reduced by at least 25%, with methanol offering the greatest benefits. This however comes at the expense of marginally higher specific CO 2 emissions than could otherwise be achieved. Overall, this work suggests that powertrains designed around the Octane-on-Demand concept may provide greater social and environmental benefits than those designed for high octane splash-blended gasolines with significant methanol or ethanol content. [ABSTRACT FROM AUTHOR]

Predicting octane numbers (ON) of gasoline surrogate mixtures is of significant importance to the optimization and development of internal combustion (IC) engines. Most ON predictive tools utilize blending rules wherein measured octane numbers are fitted using linear or non-linear mixture fractions on a volumetric or molar basis. In this work, the octane numbers of various binary and ternary n-heptane/iso-octane/toluene blends, referred to as toluene primary reference fuel (TPRF) mixtures, are correlated with a fundamental chemical kinetic parameter, specifically, homogeneous gas-phase fuel/air ignition delay time. Ignition delay times for stoichiometric fuel/air mixtures are calculated at various constant volume conditions (835 K and 20 atm, 825 K and 25 atm, 850 K and 50 atm (research octane number RON-like) and 980 K and 45 atm (motor octane number MON-like)), and for variable volume profiles calculated from cooperative fuel research (CFR) engine pressure and temperature simulations. Compression ratio (or ON) dependent variable volume profile ignition delay times are investigated as well. The constant volume RON-like ignition delay times correlation with RON was the best amongst the other studied conditions. The variable volume ignition delay times condition correlates better with MON than the ignition delay times at the other tested conditions. The best correlation is achieved when using compression ratio dependent variable volume profiles to calculate the ignition delay times. Most of the predicted research octane numbers (RON) have uncertainties that are lower than the repeatability and reproducibility limits of the measurements. Motor octane number (MON) correlation generally has larger uncertainties than that of RON. [ABSTRACT FROM AUTHOR]