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Oka T.,Research Institute of Electronics | Hojo H.,University of Shizuoka
Langmuir | Year: 2014

We report a simple method to produce a single crystal region of an inverse bicontinuous cubic (QII) phase of a lipid, 1-monoolein. By starting with the lipid of the sponge (L3) phase in the presence of 1,4-butanediol, we can obtain a single crystal region of the double-diamond QII phase in 1 week by controlled dilution of 1,4-butanediol. The length of the single crystal region in a 0.5 mm diameter capillary was on the order of millimeters. X-ray diffraction images of the region showed diffraction "spots", but not "rings" as in powder diffraction. The diffraction images also changed rotation angle dependently. We could assign Miller indices to all of the distinguishable diffraction spots from the region. This method would bring benefits to the basic and applied research areas of the Q phases. © 2014 American Chemical Society.


Singh A.,Bhabha Atomic Research Center | Samanta S.,Bhabha Atomic Research Center | Kumar A.,Bhabha Atomic Research Center | Debnath A.K.,Bhabha Atomic Research Center | And 5 more authors.
Organic Electronics: physics, materials, applications | Year: 2010

The charge transport properties of 100 nm thick cobalt phthalocyanine (CoPc) films grown on single crystal Al2O3 (0 0 0 1 oriented) and quartz substrates using molecular-beam epitaxy, have been investigated as a function of applied bias (±50 V) and temperature (300-75 K). Films grown on Al2O3 are highly ordered and exhibited non-hysteretic current-voltage (J-V) characteristics. The J-V characteristics in this case are well described by space-charge-limited conduction (SCLC) mechanism. On the other hand, films grown on quartz substrates are highly disordered and exhibited hysteretic J-V characteristics. Analyses of complex hysteretic J-V's in disordered films indicated a transition from trap-controlled SCLC mechanism to Poole-Frankel emission with lowering temperature. Various parameters, such as, hole density, trap concentration and space charge limited motilities have been estimated. X-ray photoelectron spectroscopy data show that charge trapping centers in the films grown on quartz substrates are created by chemisorbed oxygen. © 2010 Elsevier B.V. All rights reserved.


Garg K.,Bhabha Atomic Research Center | Singh A.,Bhabha Atomic Research Center | Debnath A.K.,Bhabha Atomic Research Center | Nayak S.K.,Bhabha Atomic Research Center | And 6 more authors.
Chemical Physics Letters | Year: 2010

We present chemiresistive sensing characteristics of spin-coated thin films of newly synthesized bis-porphyrin molecules that involves anchoring of two porphyrins to a benzene ring at meta positions through ester-linkages. The bis-porphyrin films are very smooth (rms roughness <2 nm) and exhibit high charge mobility (1.8 cm2/V s). These films are found to be highly selective to Cl2 with fast response (3 s) and recovery (∼8 min) times, and sensitivity in the 10-500 ppb range varies linearly between 278% and 1370%. However, for concentrations ≥1000 ppb, the response becomes irreversible, which is attributed to the chemical reaction between Cl2 and bis-porphyrin films. © 2010 Elsevier B.V. All rights reserved.


Samanta S.,Bhabha Atomic Research Center | Aswal D.K.,Research Institute of Electronics | Singh A.,Bhabha Atomic Research Center | Debnath A.K.,Bhabha Atomic Research Center | And 4 more authors.
Applied Physics Letters | Year: 2010

The temperature dependent current-voltage (J-V) characteristics of highly-oriented cobalt phthalocyanine films (rocking-curve width=0.11°) deposited on (001) LaAlO3 substrates are investigated. In the temperature range 300-100 K, charge transport is governed by bulk-limited processes with a bias dependent crossover from Ohmic (J∼V) to trap-free space-charge-limited conduction (J∼ V2). The mobility (μ) at 300 K has a value of ∼7 cm2 V-1 s-1 and obeys Arrhenius-type (ln μ∼1/T) behavior. However, at temperatures <100 K, the charge transport is electrode-limited, which undergoes a bias dependent transition from Schottky (ln J∼ V1/2) to multistep-tunneling (conductivity varying exponentially on the inverse of the square-root of electric field). © 2010 American Institute of Physics.


Islam M.Z.,Bioscience Technology | Ariyama H.,Bioscience Technology | Alam J.M.,Research Institute of Electronics | Yamazaki M.,Bioscience Technology | And 2 more authors.
Biochemistry | Year: 2014

The cell-penetrating peptide, transportan 10 (TP10), can translocate across the plasma membrane of living cells and thus can be used for the intracellular delivery of biological cargo such as proteins. However, the mechanisms underlying its translocation and the delivery of large cargo remain unclear. In this report we investigated the entry of TP10 into a single giant unilamellar vesicle (GUV) and the TP10-induced leakage of fluorescent probes using the single GUV method. GUVs of 20% dioleoylphosphatidylglycerol (DOPG)/80% dioleoylphosphatidylcholine (DOPC) were prepared, and they contained a water-soluble fluorescent dye, Alexa Fluor 647 hydrazide (AF647), and smaller vesicles composed of 20% DOPG/80% DOPC. The interaction of carboxyfluorescein (CF)-labeled TP10 (CF-TP10) with these loaded GUVs was investigated using confocal microscopy. The fluorescence intensity of the GUV membrane increased with time to a saturated value, then the fluorescence intensity due to the membranes of the smaller vesicles inside the GUV increased prior to leakage of AF647. This result indicates that CF-TP10 entered the GUV from the outside by translocating across the lipid membrane before CF-TP10-induced pore formation. The rate constant of TP10-induced pore formation in lipid membranes increased with an increase in TP10 concentration. Large molecules such as Texas Red Dextran 40 000, and vesicles with a diameter of 1-2 μm, permeated through the TP10-induced pores or local rupture in the lipid membrane. These results provide the first direct experimental evidence that TP10 can deliver large cargo through lipid membranes, without the need for special transport mechanisms such as those found in cells. © 2014 American Chemical Society.


Zenin V.V.,Voronezh State Technical University | Stoyanov A.A.,Research Institute of Electronics | Petrov S.V.,OAO Voronezh Plant of Semiconductor Devices Assembly | Chistyakov S.Yu.,OAO Voronezh Plant of Semiconductor Devices Assembly
Russian Microelectronics | Year: 2014

Some methods of the formation of microwelds, which are most acceptable for the assembly of 3D-wares with the use of wire leadouts, have been analyzed. Some peculiarities of the bonding of inner wirings on a die and a package by different welding methods, such as pressure welding with indirect pulsed heating and thermosonic, ultrasonic, and split-tip welding, have been considered. The effect of structural and technological factors on the quality of microwelds made by ultrasonic welding with the use of aluminum wire, aluminum metallization on a die, and gold, nickel, and nickel alloy coatings has been studied. Some information on microwelds made with the use of copper wire and copper metallization has been represented. © 2014 Pleiades Publishing, Ltd.


Seredin P.V.,Voronezh State University | Goloshchapov D.L.,Voronezh State University | Lenshin A.S.,Voronezh State University | Ternovaya V.E.,Voronezh State University | And 5 more authors.
Semiconductors | Year: 2015

Structural and spectroscopic methods are used to study the epitaxial layers of n-type AlxGa1 − xAs solid solutions produced by the metal-organic chemical vapor deposition method. It is shown that, when AlxGa1 − xAs solid solutions are doped with carbon to a level of (1.2–6.7) × 1017 cm−3, the electron mobility is anomalously high for the given impurity concentration and twice exceeds the calculated value. It is assumed that the ordered arrangement of carbon in the metal sublattice of the solid solution leads to a change in the average distance between impurity ions, i.e., to an increase in the mean free path of the carriers and, consequently, in the carrier mobility. The observed effect has immediate practical importance in the search for various technological ways of increasing the operating speed of functional elements of modern optoelectronic devices. The effect of the anomalously high carrier mobility in the epitaxial layer of a heteropair opens up new opportunities for the development of new structures on the basis of AlxGa1 − xAs compounds. © 2015, Pleiades Publishing, Ltd.


Pazos S.,Research Institute of Electronics | Hurtado M.,Research Institute of Electronics | Hurtado M.,National University of La Plata | Muravchik C.H.,Research Institute of Electronics | And 2 more authors.
IEEE Transactions on Signal Processing | Year: 2015

We consider the problem of estimating a signal which has been corrupted with structured noise. When the signal of interest accepts a sparse representation, only a small number of measurements are required to retain all the information. The measurements are mapped to a lower dimensional space through a projection matrix. We propose a method to optimize the design of this matrix where the objective is not only to reduce the amount of data to be processed but also to reject the undesired signal components. As a result, we reduce the computation time and the error on the estimation of the unknown parameters of the sparse model, with respect to the uncompressed data. The proposed method has tunable parameters that can affect its performance. Optimal tuning would require a comprehensive study of parameter variations and options. To avoid this learning burden, we also introduce a variant of the algorithm that is free from tuning, without significant loss of performance. Using synthetic data, we analyze the performance of the proposed algorithms and their robustness against errors in the model parameters. Additionally, we illustrate the performance of the method through a radar application using real clutter data with a still target and with a synthetic moving target. © 1991-2012 IEEE.

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