Volatiles of <Emphasis Type="Italic">Solena amplexicaulis</Emphasis> (Lam.) Gandhi Leaves Influencing Attraction of Two Generalist Insect Herbivores

Epilachna vigintioctopunctata Fabr. (Coleoptera: Coccinellidae) and Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) are important pests of Solena amplexicaulis (Lam.) Gandhi (Cucurbitaceae), commonly known as creeping cucumber. The profiles of volatile organic compounds from undamaged plants, plants after 48 hr continuous feeding of adult females of either E. vigintioctopunctata or A. foveicollis, by adults of both species, and after mechanical damaging were identified and quantified by GC-MS and GC-FID analyses. Thirty two compounds were detected in volatiles of all treatments. In all plants, methyl jasmonate was the major compound. In Y-shaped glass tube olfactometer bioassays under laboratory conditions, both insect species showed a significant preference for complete volatile blends from insect damaged plants, compared to those of undamaged plants. Neither E. vigintioctopunctata nor A. foveicollis showed any preference for volatiles released by heterospecifically damaged plants vs. conspecifically damaged plants or plants attacked by both species. Epilachna vigintioctopunctata and A. foveicollis showed attraction to three different synthetic compounds, linalool oxide, nonanal, and E-2-nonenal in proportions present in volatiles of insect damaged plants. Both species were attracted by a synthetic blend of 1.64 μg linalool oxide?+?3.86 μg nonanal?+?2.23 μg E-2-nonenal, dissolved in 20 μl methylene chloride. This combination might be used as trapping tools in pest management strategies.     

A binomially distributed photonic bandgap structure (PBGS) and its application to bandpass filter

Conventional hole‐patterned photonic bandgap structures (PBGSs) yield distinct and wide stopband, but suffer from a significant ripples in the passband beyond the optimized filling factor (FF) of 0.25. Binomial distribution in PBGSs can yield improved performance beyond this value. The optimum FF of binomially distributed PBGSs has been ivestigated at multifrequencies in the X‐band, namely, at 9, 10.5, and 12 GHz. It can be seen that 0.4 may be considered as the optimum FF for binomially distributed PBGSs at different frequencies within X‐band operations. Finally, binomially PBGSs with this optimium FF are applied in a bandpass filter (BPF) for suppresing the intrinsic spurious harmonics of a BPF. The various experimental investigations reveal that the variation in number of PBG elements and their locations affect the performance of harmonic suppression. Binomially distributed PBGSs are found to be potential candidate to suppress the harmonic signal and to improve the return‐ and insertion‐loss bandwidths. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Planar electromagnetic bandgap structures

This article presents various novel and conventional planar electromagnetic bandgap (EBG)‐assisted transmission lines. Both microstrip lines and coplanar waveguides (CPWs) are designed with circular, rectangular, annular, plus‐sign and fractal‐patterned EBGs and dumbbell‐shaped defected ground structure (DGS). The dispersion characteristics and the slow‐wave factors of the design are investigated. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

RFID Transponders

adio frequency identification (RFID) or auto-identification (ID) is a contactless data transmission and reception technique between the data carrying device, called a transmitter responder (transponder) or an RFID tag, and an interrogator, which is also known as an RFID reader. A more abstract approach to defining Auto-ID reveals that Auto-ID involves the automated extraction of the identity of an object [1], [2]. The contactless ID system relies on data transmission via radio frequency electromagnetic (EM) signals, and consequently, the whole operation is line-of-sight and weather independent [3]. These advantages overcome the limitations of optical barcodes, which are line-of-sight and weather dependent and need manual operation.     

Evaluation of Abrasive Wear Resistance of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/7075 Composite by Taguchi Experimental Design Technique

Two-body abrasive wear resistance of 7075 Al-alloy reinforced with 20 wt% Al₂O₃ particles has been studied with reference to unreinforced base alloy by design of experimental technique. Taguchi L₉ orthogonal array and analysis of variance techniques considering four factors, i.e., load, size of SiC abrasive particle, velocity and sliding distance, each at three different levels, have been employed. The experimental results reveal that wear resistance of composite is far superior than that of the unreinforced base alloy under any given test condition. In general, the most dominating factor is found to be the size of abrasive particle followed by load for both base alloy and composite. The confirmation tests reveal the accuracy level ±?5.52 and ±?6.06% for base alloy and composite, respectively. Mechanism of abrasive wear and the difference of wear response of base alloy and composite are discussed via characterizations of worn surface and generated wear debris.     

Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti₂O₃ (titanium sesquioxide), anatase and rutile phases of TiO₂ on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.     

Biodegradable drag reducing agents and flocculants based on polysaccharides: Materials and applications

Organic and inorganic flocculants are used in treatment of water and industrial effluents. Polymeric flocculants, synthetic as well as natural, because of their natural inertness to PH changes, low dosage, and easy handling, have become very popular in industrial effluent treatment. It has been established in the authors' laboratory that by grafting polyacrylamide branches on rigid backbone of polysaccharides, the dangling grafted chains have easy approachability to contaminants in effluents. Thus grafted polysaccharides are very efficient, shear stable and biodegradable flocculants. They also exhibit turbulent drag reducing characteristics. Among grafted guar gum, xanthan gum, carboxymethyl cellulose, and starch, grafted starch performs the best. Starch consists of amylose (a low molecular weight linear polymer) and amylopectin (a high molecular weight, branched polymer). The grafted amylopectin is found to be the best flocculant for various kinds of industrial effluents, providing credibility to the above‐cited model. In the present paper, the details about grafted polysaccharides as turbulent drag reducers and flocculants are given, along with their applications.     

Support Vector Machines for Automated Recognition of Obstructive Sleep Apnea Syndrome From ECG Recordings

Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular morbidity as well as excessive daytime sleepiness and poor quality of life. In this study, we apply a machine learning technique [support vector machines (SVMs)] for automated recognition of OSAS types from their nocturnal ECG recordings. A total of 125 sets of nocturnal ECG recordings acquired from normal subjects (OSAS- ) and subjects with OSAS (OSAS+), each of approximately 8 h in duration, were analyzed. Features extracted from successive wavelet coefficient levels after wavelet decomposition of signals due to heart rate variability (HRV) from RR intervals and ECG-derived respiration (EDR) from R waves of QRS amplitudes were used as inputs to the SVMs to recognize OSAS +/- subjects. Using leave-one-out technique, the maximum accuracy of classification for 83 training sets was found to be 100% for SVMs using a subset of selected combination of HRV and EDR features. Independent test results on 42 subjects showed that it correctly recognized 24 out of 26 OSAS + subjects and 15 out of 16 OSAS - subjects (accuracy = 92.85%; Cohen's kappa value of 0.85). For estimating the relative severity of OSAS, the posterior probabilities of SVM outputs were calculated and compared with respective apnea/hypopnea index. These results suggest superior performance of SVMs in OSAS recognition supported by wavelet-based features of ECG. The results demonstrate considerable potential in applying SVMs in an ECG-based screening device that can aid a sleep specialist in the initial assessment of patients with suspected OSAS.     

Shorting strap tunable single feed dual-band PIFA

RF switches are integrated to the shorting straps of a single feed dual-band planar inverted-F antenna (PIFA) to make a tunable PIFA. The L-band switch yields 0.45-dB insertion loss (IL) and 10-dB isolation bandwidth (BW) of 40% at 1.5 GHz. The tunable PIFA yields 39% impedance BW at 900-MHz band and 7.8% BW at 2000-MHz band. The measured radiation patterns are nearly omni-directional and yield a gain of -7.8 dBi at 652 MHz and 4.3 dBi at 2104 MHz.