022118   Ashtekar A (Physics Dep, Institute for Gravitational Physics and Geometry, Penn State, University Park, PA 16802, USA, Email: ashtekar@gravity.psu.edu) : Space and time: from antiquity to Einstein and beyond. Resonance 2006, 11(9), 4-19.

At the beginning of the 20th century, Einstein revolutionized the notions of space and time, first through special relativity and then, a decade later, through general relativity. Conceptual ideas " underlying general relativity are explained and its physical ramifications summarized in general terms, without recourse to advanced mathematics. This theory is perhaps the most sublime creation of the human mind. Nonetheless, it has become increasingly clear that it too has serious limitations which can be overcome only through another dramatic revision of our notions of space and time. Concludes by providing glimpses of what awaits us in the 21st century.

2 illus, 8 ref

022117   Arakeri J H;Dharuman C (Mechanical Engineering Dep, Indian Institute of Science, Bangalore-560 012, Email: jaywant@mecheng.iisc.ernet.in) : Fluid statics and archimedes. Resonance 2006, 11(10), 28-39.

The equations of fluid statics derive from the fact that in a stationary fluid only normal stress (pressure) is present and tangential stresses are absent. Derives equations for variation of pressure in a static fluid or in one that is moving as a rigid body. Also, we show that surfaces of constant pressure and constant density should coincide. Various types of instabilities related to submerged bodies and multi layerd fluids are briefly discussed.

8 illus, 3 ref

021262   Zhou C;Dai E;Wang S (NO, Information Optics Lab. Shanghai Institute of Optics and Fine Mechanic, PO Box 800-211, Shanghai 201 800, P. R. China, Email: chazhou@mail.shenc.ac.cn) : Microoptical elements for characterization of femtosecond laser pulses. Asian J Phys 2006, 15(3-4), 301-5.

Summarizes works on design and fabrication of the novel microoptical elements for femtosecond applications. Authors found the optimized condition of inductively coupled plasma equipment for etching fused silica gratings, so deep etched optical elements for high efficiency can be fabricated. Developed a two layered structure with the reflective Dammann gratings for splitting and measurement of the femtosecond laser pulses. The most attractive feature of this approach is that the conventional beam splitter is avoided. The conventional beam splitter would introduce the unequal dispersion due to the broadband spectrum of high-power ultrashort laser pulses. Implemented the Dammann FROG apparatus by using two-layered reflective Dammann gratings for measurements of the short pulses of 11.7 fs, the simple pulse of 77 fs, and the complex pulses over 1000 fs, Excellent experiments are obtained with the small FROG errors. Novel microoptical elements are useful for developing new femtosecond information processing techniques.

3 illus, 22 ref

021261   Zheng Y;Yingpeng L;Jun C (Precision Instrument Dep, Tsinghua Univ, Beijing, China) : Measurement of novel micro bulk defects in semiconductive materials based on mie scatter. Indian J pure appl Phys 2007, 45(4), 372-6.

Introduces a new micro bulk defects measurement method in semiconductive materials, which scales the defects by analyzing scattering light distribute based on Generalized Lorenz and Mie Theory (GLMT). A method named character recognition and pick up two characters as defect criterions have been presented. Moreover, a set of experimental apparatus is built to prove the detect method and defect criterions. The micro bulk defects in semiconductive materials have been detected experimentally.

5 illus, 4 table, 4 ref

021260   Zhang W;Xue C;Xiong J;Xie B;Wei T;Chen Y (Kay Lab of Instrumentation Science & Dynamic Measurement of Ministry, , ) : Piezoresistive effects of resonant tunneling structure for application in micro-sensors. Indian J pure appl Phys 2007, 45(4), 294-8.

Piezoresistive properties of resonant tunneling structure made of undoped InGaAs/AlAs double-barrier quantum layers have been experimentally investigated, and the resonant tunneling structure was grown by molecular beam epitaxy (MBE) on semi-insulation (001)-oriented GaAs substrate. We found that the piezoresistivity of such quantum layers is about one order higher than that of the commonly used silicon structures. Micro accelerometers based on InGaAs/AlAs double-barrier resonant tunneling structures have also been designed and fabricated by control hole technique.

9 illus, 14 ref

021259   Yang X;Zhou Z;Wu Y;Xiao M;Luo Q;Shao C (Precision Instruments & Mechanology Dep, Tsinghua Univ, MEMS Lab, P R China, Email: yangxing@mail.tsinghua.edu.cn) : Measurement and simulation of carbon nanotube's piezoresistance property by a micro/nano combined structure. Indian J pure appl Phys 2007, 45(4), 282-6.

The present status of carbon nanotube's electromechanical properties was reviewed. The relationships among the carbon nanotube's resistance, gauge factor and the rates of change of the band gaps with strain (dE_g/dε) were analyzed and simulated. Then, a micro/nano combined device and method for measuring the piezoresistance property of carbon nanotube were proposed. The device is consisted of a silicon chip and a printed circuit board which is used for loading and leading wire. The microelectrodes were fabricated on ,the silicon chip by FIB and a CVD-growth single-wall carbon nanotube was connected with the microelectrodes. The voltage-current characteristic of the carbon nanotube was measured using the proposed device. The relationship between the current and the voltage is basically linear, which demonstrates that the carbon nanotube is metallic. The experimental results show that the micro/nano combined device can be used for measuring the piezoresistance of carbon nanotube in our future work.

6 illus, 9 ref

021258   Yadav D P (NO, , At P.O. Sahugarh (Hulas Tola), Madhipura, Bihar) : Gain of antennas. Acta Cienc Indica-Phys 2006, 32(1), 55-6.

Point-to-point or point-to-multipoint communications the gains of the transmitting and receivªing antennas have a significant impact on system performance. Recent interest in wireless applications has increased the need of system engineers to estimate antenna gain accurately. Since the gain is the most important performance parameter of an antenna. It is not possible to calculate the gain of an antenna in several practical situations. Though there are several formulas for estimating gain with certain limitations giving thereby in accurate results. Presents an accurate gain process of evaluation.

5 ref

021257   Wu Y;Zhou Z;Yang X;Xiao M;Luo Q;Zhang J;Zhang Y Y;Yao Y (State Key Lab. of Precision Measurement Technology and Instrumentation, Tshinghua Univ, Beijing, 100084, P R China) : Fabrication of single-walled carbon-nanotube with metallic electrodes. Indian J pure appl Phys 2007, 45(4), 368-71.

Aligned array of single-walled carbon nanotubes on a substrate is synthesized by chemical vapour deposition of methane. The combined synthesis and FIB technique presented here demonstrated the nanotube devices with metallic electrodes. Sample characterization was carried out with SEM pictures and I-V curves, which show that the nanotube with metallic electrodes may be widely used in both basic research and applications.

3 illus, 5 ref

021256   Wilkinson T D;Gil-Leyva D;Henderson C (Engng Dep, Cambridge Univ, Trumpington St, Cambridge CB2 1PZ, Email: tdw@eng.cam.ac.uk) : Adaptive reconfgurable optical interconnects. Asian J Phys 2006, 15(3-4), 223-31.

The next generation of applications for liquid crystal over silicon technology will be non-display oriented systems such as adaptive optical interconnects, optical switches and optical image processors. Developing these new applications both as reconfigurable optical interconnects (or switches) and adaptive optical interconnects. There is a growing need for optically transparent interconnects in both telecommunications networks as well as board to board and chip to chip systems and reconfigurable phase gratings or holograms offer a very exciting solution. Free space optical data transmission is becoming more and more important as the data rate in electronic systems increases into the GHz region in order to avoid data bottlenecks. Past research into free-space optical links has shown that a high level of manufacturing tolerance must be used to maintain the link, however, one way of avoiding these limitation is to use a reconfigurable liquid crystal phase hologram as a beam steering element to compensate for movement between the boards and maintain the optical data path. Present recent results in utilising phase holograms to steer free space optical beams in both a telecommunications switch and a board to board interconnect.

9 illus, 14 ref

021255   Vinod Kumar;Pant R P;Halder S K;Yadav M S (X-ray Section, National Physical Laboratory, Dr K S Krishnan Marg, New Delhi-110 012) : Development of ferrofluid and its possible applications in MEMS. Indian J pure appl Phys 2007, 45(4), 406-10.

In micro-fluidic devices, fluid control plays a crucial role in its operation. The input and output in the device must pass through control surface. Synthesized nano magnetic fluid is characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) techniques for its potential applications in MEMS devices as gas pressure valve. Operation of gas pressure valve was monitored at varying electromagnetic actuation level.

6 illus, 1 table, 11 ref

021254   Vijaya Ragavan R;Srinivasan N (Physics Dep, D.A.A. College, Dharmapuram, Mayiladuthurai, Tamil Nadu) : Variation of lipid content in kidney of Albino mouse treated with sildenafil citrate (VIAGRA) using FTIR spectral technique. Acta Cienc Indica-Phys 2006, 32(1), 57-62.

Significant change in Lipid content has been detected from the FTIR spectral analysis of kidney of control and the experimental Albino mouse. This observed change in Lipid content has been well correlated with the function of the kidney.

4 illus, 2 tables, 19 ref

021253   Verma A S;Rathi S K;Sharma D;Bhardwaj S R (Physics Dep, B.S.A. College, Mathura-281 004) : Thermodynamics property of binary rare-earth compopunds. Acta Cienc Indica-Phys 2006, 32(1), 65-70.

Empirical relationship has been derived for heats of formation determination of the rare earth susquioxide and rare earth pnictides. (e.g.. A_xB_y types compounds). The modified relation has been evolved in terms of lattice parameter. Applies the proposed relation on a wide range of compounds and found a better agreement with the values evaluated by earlier workers.

2 illus, 3 tables, 16 ref

021252   Vaishnavi C;Sukhminderjit Kaur;Manpreet Kaur (Gastroenterology Dep, Postgraduate Institute of Medical Education and Research, Chandigarh-160 012, Email: cvaishnavi@sify.com) : Bactericidal activity of kitchen spices and condiments on enteropathogens. Nat Prod Radiance 2007, 6(1), 40-5.

The medicinal value of many of the spices and condiments used in Indian cooking has been known for centuries. The aim of this study was to evaluate the bactericidal activity of spices and condiments used in the Indian kitchen on enteropathogens endemic to our country. Aqueous extracts of onion (Allium cepa Linn.), garlic (Allium sativum Linn.), ginger (Zingiber officinale Rosc.), black pepper (Piper nigrum Linn.), clove [Syzygium aromaticum (Linn.) Merrill & Perry], asafoetida (Ferula assafoetida Linn.), omum (Bishop's weeds) Trachyspermum ammi (Linn.) Sprague syn. Carum copticum Hiern.], mint (Mentha spicata Linn. emend. Nathh. syn. M. viridis Linn.), cumin seeds (Cuminum cyminum Linn.) and turmeric(Curcuma domestica Valeton) were used in the study. Their antimicrobial activity against various diarrhoeagenic bacteria, viz. Salmonella typhi, S. typhimurium, Shigella flexneri, Sh. dysenteriae, Escherichia coli, Yersinia enterocolitica and Campylobacter jejuni were investigated by the disc diffusion and growth inhibition methods. Extracts of clove showed maximal antimicrobial activity against all the enteropathogens investigated. Black pepper showed antimicrobial effect on Sh. dysenteriae, C. jejuni, E. coli 0157 and E. coli 0102. Ginger and mint showed the least bactericidal effect on the enteropathogens studied. The remaining spices and condiments showed different degree of activity with different microbes. Spices and condiments, thus not only add flavour to the Indian cooking, but they may also protect us from various gastrointestinal endemic diseases.

4 tables, 21 ref

021251   Tripathi D (NO, Max Planck-Institut fur Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany, Email: d.tripathi@damtp.cam.ac.uk) : EUV and coronagraphic observations of coronal mass ejections. J Astrophys Astr 2006, 27(2-3), 193-200.

The Large Angle Spectrometric Coronagraph (LASCO) and Extreme-ultraviolet Imaging Telescope (EIT) onboard Solar and Heliospheric Observatory (SOHO) provide us with unprecedented multi-wavelength observations helping us to understand different dynamic phenomena on the Sun and in the corona. Discusses the association between post-eruptive arcades (PEAs) detected by EIT and white-light coronal mass ejections (CMEs) detected by LASCO/C2 telescope.

5 illus, 25 ref

021250   Sutar D;Aswal D K;Gupta S K;Yakhmi J V (Technical Physics & Prototype Engineering Div, Bhabha Atomic Research Center, Trombay, Mumbai-400 085) : Electrochemical actuator from conductive electroactive polymer polypyrrole deposited on gold. Indian J pure appl Phys 2007, 45(4), 354-7.

Electrochemical bilayer actuators were fabricated from conductive electroactive polymer polypyrrole deposited by electrochemical polymerization. Films of polypyrrole doped with dodecylbenzene sulphonate (PPy-DBS) and with gold coating on one side were prepared by galvanostatic electrochemical polymerization of pyrrole. Polystyrene sheet (used for over-head-projector) with thermally deposited gold film, was used as working electrode. The strong interaction of pyrrole with gold was made use of to get a freestanding polypyrrole film with gold coating on one side (PPy-DBS/Au). Bilayer actuators, were fabricated from these freestanding films and tested in 1 M LiClO₄ solution. The actuator showed bending of up to 90° on both sides on electrochemical reduction/oxidation under an applied potential of 2-3 V. The applied voltage determined the response time, which was 2 to 3 s. The actuator action was also observed with low frequency ac signal.

4 illus, 11 ref

021249   Singhal D K;Singh U (Heat Transfer and Solar Energy Lab, Physics Dep, University of Rajasthan, Jaipur-302 004) : Effect of temperature on thermal conductivity of some cucurbits grown in in India. Proc Natn Acad Sci India-Sect A 2006, 76(Pt 3), 253-5.

The experiments are conducted to study the effect of temperature on effective thermal conductivity of Cucumis sativus (L) (Cucumber) and Luffa cylindrical (L) Roem (Ghia tori). The moisture content and thermal conductivity were measured by oven drying technique and by thermal probe method respectively. The effective thermal conductivity increases with increasing temperature. However, between 298 K to 303 K (near room temperature) it decreases with temperature. This behaviour needs further exploration.

4 illus, 9 ref

021248   Singh S K;Tiwari D;Sulaiman M (NO, College of Commerce, Patna-800 020) : Effect of collison of electrons on lower hybrid instabilities. Acta Cienc Indica-Phys 2006, 32(1), 89-92.

Collisional effect of electrons as well as ions have significant effect on the stability analysis of lower hybrid drift modes in the ionosphere. Electron collisions stabilize the mode and cause a density gradient threshold for the instability. This threshold results in restriction on the interpretation of 155 and 415 MHz backscatter results as being due to lower hybrid drift instabilities and suggests measurement to determine whether the instability can account for the backscatter.

3 ref

021247   Singh N;Singh V (Physics Dep, T D P G College, Jaunpur-222 002, Email: n_nirajsingh007@rediffmail.com) : Off-axis field amplitude variation for plane and paraboloidal zone plate: A comparative study. Natn Acad Sci Lett 2006, 29(9-10), 367-73.

Comparative study of the plane and the paraboloidal zone plate has been made in respect of off-axis field amplitude variation on a transverse plane. After a brief theoretical analysis, the results of a detailed numerical computation have been presented. It is found that the side-lobes corresponding to the parabolodial zone plate are much less pronounced than those for the plane zone plate.

^ssc3 illus, 7 ref

021246   Shukla R P;Udupa D V (Spectroscopy Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Testing of concave cylindrical mirrors, positive cylindrical lenses and elliptical cylinder using a low frequency linear grating. J Optics 2006, 35(2), 65-73.

Application of equidistant low frequency grating for testing of concave cylindrical mirrors and positive cylindrical lenses is described. The equipments needed for the testing of cylindrical mirrors are visible He-Ne laser, microscope objective, well corrected collimating lens and low frequency grating. The method is found to be useful for revealing the hills, valleys and zonal errors of cylindrical surfaces of medium radius of curvature. The method is useful for estimating the uniformity of cylindrical wavefront emerging out of a cylindrical lens. A method for testing elliptical cylinder surface has also been proposed.

6 illus, 26 ref

021245   Sharp J H;Shi C W P;Watson I A;Seat H C (Leser & Optical systems Engineering Centre, Mechanical Engineering De, Univ of Glasgow, Glasgow G12 8QQ, U K) : Production and applications of single crystal optical fibres. Asian J Phys 2006, 15(3-4), 233-42.

Single-crystal fibres combine the material benefits of optical crystals with a waveguiding device geometry. As such they offer potentially significant advantages over conventional optical fibres in some specific fields. However, research in this area has been slow to gather momentum and to fully realise this potential. Reviews production methods of single-crystal fibres along with the applications which have been addressed to date along with future application areas. In addition, specific reference is made to the recent work carried out by the authors.

5 illus, 1 table, 49 ref

021244   Sharma P;Koul S K;Chandra S (Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz-Khas, New Delhi-110 016, Email: shiban_koul@hotmail.com) : Studies on RF MEMS shunt switch. Indian J pure appl Phys 2007, 45(4), 387-94.

Radio Frequency Micro-Electro-Mechanical-Systems (RF MEMS) based switches are expected to play a key role in the field of microwave switching. Traits like low-loss performance; zero-power consumption and very low inter-modulation distortion have made these switches well suitable for high-performance microwave and millimeter-wave circuits. The design of RF MEMS switches, however, require sophisticated modeling techniques because of their complicated 3-D geometries with critical aspect ratios and strong in-homogeneities. In this paper, the effect of various geometric dimensional parameters on the electromagnetic and mechanical behaviour of a shunt capacitive MEMS switch using finite element method based Ansoft High Frequency Structure Simulator (HFSS) software tool has been presented. This exercise will provide a better insight into designing a reliable and high-performance MEMS shunt switch.

11 illus, 4 tables, 5 ref

021243   Shamir J (Electrical Engng Technion Dep, Israel Institute of Technol, Haifa 32000, Israel) : Volume holographic information storage and beam structuring. Asian J Phys 2006, 15(3-4), 373-86.

Increasing demands on information storage raises renewed interest in volume holography. Conventional approaches used for theoretical analysis of the volume holographic processes are not adequate when complicated wavefronts are involved since they can only deal with simple cases. The present work exploits the fact that most holographic systems involve several waves that may propagate at large angles but each of them contains only a relatively narrow spatial frequency band. Applying a recently introduced narrow band approximation together with a Fourier optics approach to volume holography author analyze the capabilities of volume holographic information storage as well as the use of volume holograms for beam shaping. Simulation results demonstrate the power of the method and show good correspondence with earlier experimental studies.

7 illus, 14 ref

021242   Schmieder B (NO, Observatoire de Paris, LESIA, 92195, Meudon CEDEX Prinicipal, France, Email: brigitte.schmieder@obspm.fr) : Magnetic source regions of coronal mass ejections. J Astrophys Astr 2006, 27(2-3), 139-49.

Majority of flare activity arises in active regions which contain sunspots, while Coronal Mass Ejection (CME) activity can also originate from decaying active regions and even so-called quiet solar regions which contain a filament. Two classes of CME, namely flare-related CME events and CMEs associated with filament eruption are well reflected in the evolution of active regions. The presence of significant magnetic stresses in the source region is a necessary condition for CME. In young active regions magnetic stresses are increased mainly by twisted magnetic flux emergence and the resulting magnetic footpoint motions. In old, decayed active regions twist can be redistributed through cancellation events. All the CMEs are, nevertheless, caused by loss of equilibrium of the magnetic structure. With observational examples it shows that the association of CME, flare and filament eruption depends on the characteristics of the source regions.

5 illus, 54 ref

021241   Saxena S K (Physics Dep, Upadhi (P.G.) Mahavidyalaya, Pilibhit-262 001, ) : Abstract mathematical approach for existence and completeness of linear wave operators. Acta Cienc Indica-Phys 2006, 32(1), 105-12.

Derives the existence of W₊ (H; H₀; J) by means of auxiliary manifolds under continuity assumptions on G_ε(λ) : = G(λ+iε) = J - VR₀ (λ+iε), V = HJ - JH₀; J dom H₀ ⊆ dom H, and under the assumption that the canonical approximate spectral form f^H_ε (λ; .,.) is equicontinous.

11 ref

021240   Saxena M;Jain S;Gupta Y K (Applied Sciences and Humanities Dep, Moradabad Institute of Technology, Moradabad-244 001) : Phase change recording in 12-inch worm optical disk drive. Acta Cienc Indica-Phys 2006, 32(1), 21-2.

Optical Write-Once-Read-Many (WORM) recording is a mature technology. It should be clear that a phase change material is not intrinsically rewritable and that a considerable amount of engineering is involved in making a product capable of supporting numerous write/erase cycles. Phase change materials for use on WORM media are engineered instead to give stability, durability and longevity and in this respect they actually outperform the classic ablative layers. Channel-encoded data, with ECC protection, in a WORM Phase Change layer can never be altered.

4 ref

021239   Saxema M;Jain S;Gupta Y K (Applied Sciences and Humanities Dep, Moradabad Institute of Technology, Moradabad-244 001) : Digital versatile disc-advance in optical disc technology. Acta Cienc Indica-Phys 2006, 32(1), 43-4.

DVD-RAM is a re-writable version of DVD upon which content can be recorded more than once. Data is recorded randomly on the disc. These discs can be re-recorded over 100,000 times. In 1991, a 3.5" MO disc for data recording was introduced. Then, in 1993, digital audio mini-disc was launched to the consumer market. Optical media such as MO, CD-R and DVD are rapidly becoming the next generation recording media. The. shift to digital sound and video, along with increasing quantities of data handled by computers, is expected to spur strong growth of the DVD market in the coming one to two years.

1 table, 19 ref

021238   Saminadan V;Meenakshi M (Electronics and Communiction Engineering Dep, Pondicherry Engineering College, Pondicherry-605 014, Email: sivan_saminadan@yahoo.com) : Dynamic lightpath establishment in WDM optical networks under the constraints of transmission impairments. J Optics 2006, 35(2), 78-100.

Considers the physical layer transmission impairments while establishing a call in a wavelength-routed optical network. The impact of different routing and wavelength assignment (RWA) algorithms on the crosstalk performance of a 4x4 mesh-torus and a 15-node mesh network has been studied. Considers both switch-induced crosstalk and the crosstalk induced by the multiplexers and demultiplexers. A fast and accurate approach is employed to study the impact of gain saturation of Erbium-doped fibre amplifiers (EDFA's) on the received signal quality of a 15-node network of interconnected rings. Previous works have approximated the measured EDFA gain curve by curve fitting approach. EDFA gain is numerically detained using the fast and accurate approach. The crosstalk and EDFA gain saturation can lead to poor received signal quality at the destination node. This results in increased receiver bit error rate (HER). This implied that some of the routes will deliver a signal quality which is unsatisfactory. To ensure that no resources are wasted on those connections which cannot deliver an acceptable signal quality, this paper uses an event-driven simulation which incorporates on-line BER calculations. A call is accepted only if the BER at the destination node is less than 10¹²; otherwise it is rejected.

23 illus, 2 tables, 31 ref

021237   Sains B S (Physics Dep, Punjab University, Patiala-147 002) : Regge phenomenology and pion-nucleon charge exchange scattering at GEV energies. Acta Cienc Indica-Phys 2006, 32(1), 9-12.

Pion-nucleon charge exchange scattering at few GeV energies is studied using Regge phenomenology. Charge exchange differential scattering cross-sections throughout the t-range 0 ≤ t ≤ 1.5 (GeV/c)²) are calculated using Regge theory and are compared with the available experimentaal data.

1 illus, 9 ref

021236   Rudra Pratap;Arun Kumar A (Mechanical Engineering Dep, Cranes Sci MEMS Lab, Indian Institute of Science, Bangalore-560 012) : Material selection for MEMS devices. Indian J pure appl Phys 2007, 45(4), 358-67.

As MEMS design matures and migrates from process centric design to performance based design, MEMS designers would need a rational method for selecting an appropriate material that is not based on ease of processing alone. While there is a growing number of thin film materials that can be used in micromachining for MEMS devices, the selection of a particular material is rarely based on quantifiable criterion that relates directly to the optimum performance of the device. In this study, we present a methodology for creating material related device performance indices that can be used for selecting best possible material for a device. This study is inspired by the Ashby approach and its extension to the microworld in recent studies, where materials are graded on material performance indices and the most appropriate material is selected from the Ashby charts so created. We extend this concept further in this paper and create device performance indices that can be used to grade MEMS materials in performance parameter space. We first create and discuss a material index for thermoelastic damping, an important index for vacuum packed dynamic MEMS devices that has been missing from the list of performance indices previously considered. We present two case studies of material selection, for a MEMS gyroscope and a MEMS ultrasound transducer, to illustrate the methodology and show two different approaches for creating optimality criterion in the presence of several competing performance indices.

5 illus, 4 table, 20 ref

021235   Ramanamurthy P V M;Ahrens R;Karmalkar S (Electrical Engineering Dep, Indian Institute of Technology Madras, 600 036, Email: karmal@ee.iitm.ac.in) : Piezoelectric microvalve. Indian J pure appl Phys 2007, 45(4), 278-81.

Normally closed microvalve is a very important component of a microfluidic: system. The fabrication of an active, normally-closed piezoelectric microvalve useful for automated drug delivery or control of fluids in microreactor systems has been studied. The microvalve has dimensions of 19 mm x 19 mm x 7 mm, an inlet diameter of 200 μm, a dead volume of 0.33 μl and has a steady-state flow-rate of about 240 seem.

5 illus, 6 ref

021234   Ramamurthy N;Subashini J (Physics Dep, Annamalai University, Annamalai Nagar-608 002) : Fourier transform-infrared analysis of some shampoos. Acta Cienc Indica-Phys 2006, 32(1), 31-6.

Throughout the ages, man has been searching many products for his beautification. Among these, he has paid much attention to the hair and also for promoting the growth and grooming of air. Of the many products of beautification of hair available in markets, the shampoos make chief beautifier and conditioner of hair. In the study, Fourier Transform - Infrared spectrum of some commercially available shampoos, Herbal and House made shampoos have been analysed. The probable assignments to observed bands have been made and the relative intensities of observed bands are also reported.

1 illus, 1 table, 13 ref

021233   Qiang X;Zhaoying Z;Junhua Z;Yanying F;Dong L; Guibin D (State Key Laboratory of Precision Measurement Technology and Instrumen, Tsinghua Univ, Beijing, China 100 084, Email: serzha@gmail.com) : Piezoelectrically actuated array microjet for biomedical purpose. Indian J pure appl Phys 2007, 45(4), 273-7.

Presents a micromachining-based piezoelectrically actuated array microjet for biomedical purposes such as inhalation drug therapy (IDT) and drug microencapsulation. The microjet consists of a reservoir and a fluid chamber, which is formed by a piezoelectric transducer bonded to a silicon chip with numerous micro nozzles. Inside the fluid chamber, a continuous pressure wave generated by the piezoelectric transducer propagates towards the silicon chip and squeezes the liquid out through the nozzles. The pressure wave in fluid chamber is numerically simulated using finite elements method to give a reference for nozzles arrangement. Diameter and velocity measurements of droplets, temperature estimations on working device and a preliminary animal experiment of IDT are done to characterize the microjet. As a result, the microjet could be a promising tool in biomedicine field.

8 illus, 8 ref

021232   Pant B D;Mahesh Kumar;Subha Lakshmi;Arora A; Prasad M;Sharma A;Patel M;Radhakrishnan S;Dwivedi V K (MEMS Laboratory, Central Electronics Engineering Research Institute, Pilani-333 031, Rajasthan) : Fabrication of MEMS composite-polymer gas sensor arrays for electronic nose. Indian J pure appl Phys 2007, 45(4), 321-5.

Sensor arrays capable of sensing different gases combined with a sampling system and a means of pattern classification and recognition comprise a basic system for an 'Electronic Nose' In the present work, a complete process for the fabrication of micro-cavities with sensing electrodes and volumes ranging from 2.5 to 12 nano-liters for the development of polymer gas sensors has been reported. An array of eight sensing cells in four sizes have been fabricated using SU-8 negative tone resist through UV-LIGA process developed at CEERI, Pilani. The length and width of the SU-8 cavities are: 250 x 250, 300 x 300, 500 x 500 and 500 x 600 micron and the depth of each of them was optimized to be 40 micron. These cavities filled with different polymer composites comprise the basic sensing cells for a variety of gases. The current paper presents the salient features of the fabrication process in detail and the results obtained in ethanol and methanol ambient using a polymer composite developed through dissolution of styrene and polyaniline in PMMA. A number of other composites such as Pc-Ppy, Pr-Ppy, Fc⁺-PPy have also been synthesized and tested for a high sensitivity in carbon monoxide.

8 illus, 9 ref

021231   Nelleri A;Joseph J;Singh K (Photonics Group, Phys Dep, Indian Instiute of Technology Delhi, Hauz khas, New Delhi-110 016, Email: kehars@physics.iitd.ac.in) : Digital holography for three-dimensional information processing: applicatin to object recognition and information security. Asian J Phys 2006, 15(3-4), 253-73.

With the use of CCD as a recording device in holography, the information regarding a complete 3-D volume can be stored in the digital hologram. The numerical reconstruction of such optically generated and digitally recorded hologram gives a quantitative measure of the intensity and phase of the complex object wavefront as digital complex images. This capability elevates the purviews of holography as a scientific and technological tool. The present paper reviews the application of digital holography in three-dimensional object recognition and allied uses for securing holographic 3-D data with special reference to investigations being carried out at IIT Delhi.

22 illus, 73 ref

021230   Navin Kumar (Mathematics Dep, University of Rajasthan, Jaipur-302 004) : Unsteady two-dimensional free-convective flow of a viscous incompressible fluid through a rotating porous medium bounded by a vertical surface. Asian J expl Sci 2007, 21(2), 389-93.

Unsteady two-dimensional free-convective flow of a viscous incompressible fluid through a rotating porous medium bounded by a vertical surface is investigated. The porous medium is rotating with uniform angular velocity. The velocity and temperature distributions are derived by using complex function and their profiles for various values of physical parameters are shown through graphs. The coefficient of skin-friction and the rate of heat transfer in terms of Nusselt number at the vertical surface are derived, discussed and their numerical values for various values of physical parameters are presented through table.

021229   Mohiddon M A;Goel P;Yadav K L;Kumar M;Yadav P K (Physics Dep, Indian Institute of Technology Smart Materials Research Laboratory, Roorkee-247 667) : Electrical and dielectrical properties of double doped BaTiO₃. Indian J Engng Mater Sci 2007, 14(1), 64-8.

Alkali (Li, Na, K) and lanthanum doped barium titanate has been prepared by solid-state reaction method. X-ray diffraction studies suggest the compound is in tetragonal phase with small change in c/a ratio. Detailed studies of dielectric constant as a function of temperature (40-300°C) and frequency (100 Hz-1 MHz) suggest that the compounds do not have relaxor behaviour and undergoes diffuse type of phase transition. Curie temperature is found to be independent of type of alkali doping and measuring frequency. However, maximum dielectric constant and resistivity are found to be strongly dependent on frequency and type of doping.

8 illus, 1 table, 21 ref

021228   Mishra M C (Physics Dep, Millat College, Darbhanga-846 004) : Variation of input impedance of microstrip antenna with frequency. Acta Cienc Indica-Phys 2006, 32(1), 117-19.

Miscrostrip antennas are a popular choice for a range of military and commercial applications because of their conformability to surfaces, ease of manufacture and durability. However, these popular antennas are often limited in their applicability due to their narrow bandwidth characteristics. The investigation has been made as a first step towards realization of a broad-band microstrip antenna structure at a lower frequency range, taking advantage of the reduction in antenna resonant length when built upon a ferrimagentic substrate. A simple and accurate theoretical formula for input impedance of a quarter wavelength microstrip antenna has been deduced and its variation with frequency has been shown by a curve.

2 illus, 7 ref

021227   Miri-Hakimabad H;Noghreiyan A V;Panjeh H (Physics Dep, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran) : Gamma shielding design studies on <. Asian J expl Sci 2007, 21(2), 249-58.

The ²⁵²Cf radioisotope and ^24l Am-Be are intense neutron emittecl that are readily encapsulated in compact, portable, sealed sources. They have wide range of applications in laboratories, industries and medicines, because of their high flux and reliable neutron spectrum. They are cost-effective neutron sources for Prompt Gamma Neutron Activation Analysis (PGNAA). PGNAA method can be used. in medicine for neutron radiography and body chemical composition analysis. ²⁵²Cf and ²⁴¹Am-Be sources generate not only neutrons, but also emit high-energy that are useless when using PGNAA method. Also the sample in medical treatments is a human body that is forced to be under the harmful bombardments of undesirable gamma-rays. In addition accumulations of these high-rate gamma-rays in the detector volume eventuate simultaneous pulses that can be piled up and distort spectra in the region of interest (ROI). All of these restrictions forced us to attenuate these gamma-rays in a practical way without being concerned about losing the neutron flux or significant undesirable alteration in the neutron spectrum. Gamma-rays contribute 68% of the total activity from a ²⁵² Cf fission neutron source and 37.5% from a ²⁴¹Am-Be. To reduce these gamma-ªray components, spherical shields of variable radius, made of Pb, Bi and Hg separately, were considered that enclosing neutron source. Gamma-ray shielding effects and optimum radius of spherical shield and the proper material have been investigated and compared with the unfiltered case, bare source, by Monte Carlo simulation, using MCNP 4C code.

021226   Miri Hakimabad H;Panjeh H;Vejdani Noghreiyan A (Physics Dep, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran) : Response function of a 3x3 in. NaI scintillation detector in the range of 0.081 to 4.438 MeV. Asian J expl Sci 2007, 21(2), 233-7.

Response functions of a 3x3 in. NaI detector, which is mainly used in PGNAA applications, have been calculated by using MCNP-4C code. Calculated results are compared with measured data by using standard γ-ray sources to check their accuracy. γ-rays from radioisotope sources were used in the range from 0.081 to 4.438 MeV for this determination. Through the precise modeling of the detector structure, the agreement between both results has been improved.

021225   Mardare I (Disign and Manufacturing of Electronic Apparatus, Technical Univ of Moldova, Stefan mare Av, 168, Chisinau MD2012, Republic of MOLDOVA, Email: Mardarei@mail.md) : Intellectual system of restoration of images on the basis of associative memory. Asian J Phys 2006, 15(3-4), 353-60.

The practical decision of problem of restoration of defective images is considered from positions of new kinds of associations between the defective image of object and its true one. For new kinds of associations are suggested processors, constructed on the basis of Hopfield network which are oriented on specificity of such associations.

4 illus, 3 ref

021224   Mardare I (Design and Manufacturing of Electronic Apparatus Dep, Technical Univ of Moldova, , Email: Mardarei@mail.md) : Restoration of images of objects of 1-st order by means of associative memory. Asian J Phys 2006, 15(3-4), 341-52.

Deals with the questions of modeling of associations between detective and true images of objects. Models of simple associations, ambiguous extensive associations, connected simple extensive associations, directed associations are suggested. The received models of associations allow to formulate requirements for designing of the processor, which restores defective images by methods of artificial intelligence. © Anita Publications. All rights reserved.

14 illus, 5 ref

021223   Mahesh Kumar;Mahant Parsad;Goswami N;Arora A; Pant B D;Dwivedi V K (NO, Central Electronics Engineering Research Institute, Pilani) : Deposition of low stress polysilicon thinfilms using low-pressure chemical vapour deposition. Indian J pure appl Phys 2007, 45(4), 400-2.

The deposition of polysilicon thin films on silicon wafers using low-pressure chemical vapour deposition (LPCVD) was carried out and the process parameters were optimized to obtain normal and 1<60> w stress films. The films of thickness 150 nm to 2 microns were deposited on 4" and 6" silicon wafers and the thickness uniformity was measured using Dektak 6M surface profiler. The thickness variation across the wafer was found to be in 5-10% range. Stress measurements were carried out using X-ray diffraction method. We were able to deposit low stress films wit stress <126>14 MPa. The quality of the films was found to be good and they were used in fabrication of MEMS based silicon devices.

1 illus, 2 tables, 4 ref

021222   Mahajan V N;Swantner W H (Aerospace Corp, , El Segundo, CA 90245, USA) : Seidel coefficients in optical testing. Asian J Phys 2006, 15(3-4), 203-9.

Determination of the Seidel aberration coefficients from Zernike aberration coefficients obtained in optical testing is discussed, and potential pitfalls in the determination process are explained.

12 ref

021221   Ma Z;Jiang J;Gong O;Wang R K (NO, Institute of Laser and Optoelectronics, Tianjin Univ, Tianjin 300072, China) : Fourier domain optical coherence tomography for biological tissue imaging. Asian J Phys 2006, 15(3-4), 243-51.

Optical coherence tomography (OCT) is a new imaging modality used to visualise the microstructures beneath tissue surface. It has been demonstrated that this technique provides images with micron resolution in a non-contact and noninvasive way. Traditional OCT is time domain OCT (TDOCT) which is characterized by its reference arm scanning. In recent years, a new approach of OCT based on Fourier domain interferometry is emerged, i.e. Fourier domain OCT (FDOCT). FDOCT avoids scanning in the reference arm, thus makes high-speed acquisition possible. This paper reviews the state-of-the-art of FDOCT. Following a discussion of the basic theory of FDOCT, different set-ups have been presented. Finally, some of the latest progress in FDOCT is listed.

5 illus, 52 ref

021220   Lehureau J C (Thales Res and Technol, Route Departementale, , 128, F-91767 Palaiseau Cedex) : Application of radar and radioastronomy techniques to optical imagery. Asian J Phys 2006, 15(3-4), 327-40.

New imaging techniques based on computed restoration from holographic wavefront detection and phase restoration of overlapping shots. Similar to the Synthetic aperture radar, this technique allow for unlimited resolutioll. optical and turbulent aberrations can be corrected. We show how this active imagery can be extended to reference less holography using coherent light and present some practical solution for wavefront detection. We discuss the convergence of Gerchberg-Saxton algorithm in experimental numerical cases and present practical implementation using a single focal plane. We analyse the convergence of muti-pupil rephasing algorithm. This technique allows for large diameter sparse aperture passive imagery using real time rephasing actuators. Finally. we discuss the possibility of synchronous detection of incoherent light and the possibility to extend radioastronomy correlation technique to the infrared dornain.

17 illus, 22 ref

021219   Lee B (School of Electrical Engng, Seoul National Univ, Kwanak-Gu Shinlim-Dong, Seoul 151-744, Korea, Email: byoungho@snu.ac.kr) : Three-dimensional display and correlator using integral imaging technique. Asian J Phys 2006, 15(3-4), 361-72.

The three-dimensional (3D) display technique using integral imaging and its application to 3D optical correlator are presented. First, the fundamental concept of integral imaging as a 3D display technique is presented. Then recent researches to improve the quality of integral 3D imaging are overviewed. The extension of the integral imaging technique for the correlation of 3D information is also described.

15 illus, 19 ref

021218   Lakhtakia A (CATMAS-Computational & Theoretical Materials Sci Group, Engng Sci & Me, Pennsylvania State Univ, Univ Park, PA 16802-6812, USA) : Narrowband and ultranarrowband filters with elctro-optic structurally chiral materials. Asian J Phys 2006, 15(3-4), 275-82.

When a circularly polarized plane wave is normally incident on a slab of a structurally chiral material with local 42 m point group symmetry and a central twist defect, the slab can function as either a narrowband reflection hole filter for co-handed plane waves or an ultranarrowband transmission hole filter for crossªhanded plane waves, depending on its thickness and the magnitude of the applied dc electric field. Exploitation of the Pockels effect significantly reduces the thickness of the slab.

6 illus, 18 ref

021217   Kuriakose S;Morrish D;Jia B;Chon J W M;Gu M (NO, Centre for Micro-Photonics, Faculty of Engng and Industrial Sci, Swinb, PO Box 218, Hawthorn, VIC-3122, Australia, Email: mgu@swin.edu.au) : Leaser tweazers using focused evanescent illumination. Asian J Phys 2006, 15(3-4), 295-300.

Reports on optical tweezers using near field illumination. The near field was generated using the geometry which was demonstrated earlier, employing the evanescent field generated by total' internal reflection of a lightly focused beam at the interface between two media. The focused evanescent field was characterised using a scanning near field optical microscope (SNOM). The characteristics of the near field tweezers were studied experimentally and theoretically and good agreement was found. The near field tweezers as demonstrated here would be of great use especially in studying the biomolecules at a nanometric scale.

5 illus, 29 ref

021216   Kumar P;Singh S K;Prasad D;Yadav S K;Singh J P;Singh K K;Mishra L K (Physics Dep, Magadh University, Bodh Gaya-824 234) : Evaluation of I-V characteristic of thin superconductors calculated from microscopic theory of resistive state. Acta Cienc Indica-Phys 2006, 32(1), 23-30.

I-V characteristic of thin superconductor were studied and values of current j has been determined for different values of the order parameter Δ₀ and `a" the length of the weak link. The theoretical results are in good agreement with those of the other workers.

2 tables, 27 ref

021215   Kumar P;Singh S K;Prasad D;Yadav S K;Singh J P;Mishra L K (Physics Dep, Magadh University, Body-Gaya-824 234) : Evaluation of upper current J_z as function of pair breaking term Γ using time dependent Landau (TGDL) equation for thin superconductors. Acta Cienc Indica-Phys 2006, 32(1), 45-50.

Evaluates the upper current J_z as a function of pair breaking parameter Γ using time depaprtment-Ginzburg Landau equation (TGDL). The theoretical calculations are in goog agreement of those of other workers.

3 tables, 20 ref