Integrated CMOS Gas Sensors

We present a low power gas sensor system on CMOS platform consisting of micromachined polysilicon microheater, temperature controller circuit, resistance readout circuit and SnO2 transducer film. The design criteria for different building blocks of the system is elaborated The microheaters are optimized for temperature uniformity as well as static and dynamic response. The electrical equivalent model for the microheater is derived by extracting thermal and mechanical poles through extensive laser doppler vibrometer measurements. The temperature controller and readout circuit are realized on 130nm CMOS technology The temperature controller re-uses the heater as a temperature sensor and controls the duty cycle of the waveform driving the gate of the power MOSFET which supplies heater current. The readout circuit, with subthreshold operation of the MOSFETs, is based oil resistance to time period conversion followed by frequency to digital converter Subthreshold operatin of MOSFETs coupled with sub-ranging technique, achieves ultra low power consumption with more than five orders of magnitude dynamic range RF sputtered SnO2 film is optimized for its microstructure to achive high sensitivity to sense LPG gas.

High P-T granulite relicts from the Imjingang belt, South Korea:Tectonic significance

This study presents a detailed description on crustal metamorphic signatures of garnet-clinopyroxene-quartz-rutile-bearing high P-T granulites, Samgot unit, Imajingang belt, northwestern Korean Peninsula that formed during Permo-Triassic regional metamorphism related to the amalgamation of East Asian continental fragments. Lenses and blocks of high P-T granulites and garnet-bearing leucosomes occur within mafic metamorphic rocks (mainly amphibolites). The mafic blocks comprise relicts of granoblastic garnet and clinopyroxene with medium-grained quartz and rutile. These relict mineral assemblages are confined to local micro-domains and constitute remnants of peak metamorphism. Plagioclase and amphibole form only as retrograde phases in medium ton coarse-grained moats that rim grain boundaries between relict peak mineral assemblages. This microstructure represents the reaction between garnet, clinopyroxene, quartz and rutile in the presence of melt to form amphibole, plagioclase and titanite with minor biotite. The leucosome domains consist of euhedral garnets within the quartz-K feldspar-plagioclase (granitic) matrix, probably representing peritectic garnet growth along with melting. The rare earth element (REE) composition of minerals also support the peritectic garnet growth with a positive Eu/Eu* (positive Eu anomaly), while the relict garnet shows a slight negative anomaly typical for high-grade granulites. The peak-metamorphic conditions calculated from thermodynamic modeling and compositional isopleths indicate a temperature around c. 900 degrees C at a pressure around c. 20 kbar. The present P-T path indicates a clear multi-stage decompression history with initial decompression and cooling followed by a stage of decompression during hydration possibly during Late Triassic exhumation. The results from this study together with the presence of eclogites from the Hongsung area suggest that the Imjingang area and the western Gyeonggi massif likely resided at crustal levels deeper than those of the eastern and southern part of the Gyeonggi massif. (C) 2009 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

3D hierarchical rutile TiO2 and metal-free organic sensitizer producing dye-sensitized solar cells 8.6% conversion efficiency

Three-dimensional (3D) hierarchical nanoscale architectures comprised of building blocks, with specifically engineered morphologies, are expected to play important roles in the fabrication of 'next generation' microelectronic and optoelectronic devices due to their high surface-to-volume ratio as well as opto-electronic properties. Herein, a series of well-defined 3D hierarchical rutile TiO2 architectures (HRT) were successfully prepared using a facile hydrothermal method without any surfactant or template, simply by changing the concentration of hydrochloric acid used in the synthesis. The production of these materials provides, to the best of our knowledge, the first identified example of a ledgewise growth mechanism in a rutile TiO2 structure. Also for the first time, a Dye-sensitized Solar Cell (DSC) combining a HRT is reported in conjunction with a high-extinction-coefficient metal-free organic sensitizer (D149), achieving a conversion efficiency of 5.5%, which is superior to ones employing P25 (4.5%), comparable to state-of-the-art commercial transparent titania anatase paste (5.8%). Further to this, an overall conversion efficiency 8.6% was achieved when HRT was used as the light scattering layer, a considerable improvement over the commercial transparent/reflector titania anatase paste (7.6%), a significantly smaller gap in performance than has been seen previously.

Robust superhydrophobicity of hierarchical ZnO hollow microspheres fabricated by two-step self-assembly

Superhydrophobic and superhydrophilic surfaces have been extensively investigated due to their importance for industrial applications. It has been reported, however, that superhydrophobic surfaces are very sensitive to heat, ultraviolet (UV) light, and electric potential, which interfere with their long-term durability. In this study, we introduce a novel approach to achieve robust superhydrophobic thin films by designing architecture-defined complex nanostructures. A family of ZnO hollow microspheres with controlled constituent architectures in the morphologies of 1D nanowire networks, 2D nanosheet stacks, and 3D mesoporous nanoball blocks, respectively, was synthesized via a two-step self-assembly approach, where the oligomers or the constituent nanostructures with specially designed structures are first formed from surfactant templates, and then further assembled into complex morphologies by the addition of a second co-surfactant. The thin films composed of two-step synthesized ZnO hollow microspheres with different architectures presented superhydrophobicities with contact angles of 150°-155°, superior to the contact angle of 103° for one-step synthesized ZnO hollow microspheres with smooth and solid surfaces. Moreover, the robust superhydrophobicity was further improved by perfluorinated silane surface modification. The perfluorinated silane treated ZnO hollow microsphere thin films maintained excellent hydrophobicity even after 75 h of UV irradiation. The realization of environmentally durable superhydrophobic surfaces provides a promising solution for their long-term service under UV or strong solar light irradiations.

Architecture designed ZnO hollow microspheres with wide-range visible-light photoresponses

It is a challenge to increase the visible-light photoresponses of wide-gap metal oxides. In this study, we proposed a new strategy to enhance the visible-light photoresponses of wide-gap semiconductors by deliberately designing a multi-scale nanostructure with controlled architecture. Hollow ZnO microspheres with constituent units in the shape of one-dimensional (1D) nanowire networks, 2D nanosheet stacks, and 3D mesoporous nanoball blocks are synthesized via an approach of two-step assembly, where the oligomers or the constituent nanostructures with specially designed structures are first formed, and then further assembled into complex morphologies. Through deliberate designing of constituent architectures allowing multiple visible-light scattering, reflections, and dispersion inside the multiscale nanostructures, enhanced wide range visible-light photoresponses of the ZnO hollow microspheres were successfully achieved. Compared to the one-step synthesized ZnO hollow microspheres, where no nanostructured constituents were produced, the ZnO hollow microspheres with 2D nanosheet stacks presented a 50 times higher photocurrent in the visible-light range (λ > 420 nm). The nanostructure induced visible-light photoresponse enhancement gives a direction to the development of novel photosensitive materials.

Tacrolimus ointment for long-term treatment of atopic dermatitis

Atopic dermatitis (AD) or atopic eczema is characterised by a superficial skin inflammation with an overall Th2 cell dominance and impaired function of the epidermal barrier. Patients also are at an increased risk for asthma and allergic rhinitis. Treatment with tacrolimus ointment inhibits T cell activation and blocks the production of several inflammatory cytokines in the skin, without suppressing collagen synthesis. The aims of this thesis were to determine: (1) long-term efficacy, safety, and effects on cell-mediated immunity and serum IgE levels in patients with moderate-to-severe AD treated for 1 year with tacrolimus ointment or a corticosteroid regimen, (2) the 10-year outcome of eczema, respiratory symptoms, and serum IgE levels in AD patients initially treated long-term with tacrolimus ointment, and (3) pharmacokinetics and long-term safety and efficacy of 0.03% tacrolimus ointment in infants under age 2 with AD. Cell-mediated immunity, reflecting Th1 cell reactivity, was measured by recall antigens and was at baseline lower in patients with AD compared to healthy controls. Treatment with either 0.1% tacrolimus ointment or a corticosteroid regimen for one year enhanced recall antigen reactivity. Transepidermal water loss (TEWL), an indicator of skin barrier function, decreased at months 6 and 12 in both tacrolimus- and corticosteroid-treated patients; TEWL for the head and neck was significantly lower in tacrolimus-treated patients. Patients in the 10-year open follow-up study showed a decrease in affected body surface area from a baseline 19.0% to a 10-year 1.6% and those with bronchial hyper-responsiveness at baseline showed an increase in the provocative dose of inhaled histamine producing a 15% decrease in FEV1, indicating less hyper-responsiveness. Respiratory symptoms (asthma and rhinitis) reported by the patient decreased in those with active symptoms at baseline. A good treatment response after one year of tacrolimus treatment predicted a good treatment response throughout the 10-year follow-up and a decrease in total serum IgE levels at the 10-year follow-up visit. The 2-week pharmacokinetic and the long-term study with 0.03% tacrolimus ointment showed good and continuous improvement of AD in the infants. Tacrolimus blood levels were throughout the study low and treatment well tolerated. This thesis underlines the importance of effective long-term topical treatment of AD. When the active skin inflammation decreases, cell-mediated immunity of the skin improves and a secondary marker for Th2 cell reactivity, total serum IgE, decreases. Respiratory symptoms seem to improve when the eczema area decreases. All these effects can be attributed to improvement of skin barrier function. One potential method to prevent a progression from AD to asthma and allergic rhinitis may be avoidance of early sensitisation through the skin, so early treatment of AD in infants is crucial. Long-term treatment with 0.03% tacrolimus ointment was effective and safe in infants over age 3 months.

Total Hip and Knee Arthoplasty for Osteoarthritis : Factors Related to the Early Outcome of Surgery

Some perioperative clinical factors related to the primary cemented arthroplasty operation for osteoarthritis of the hip or knee joint are studied and discussed in this thesis. In a randomized, double-blind study, 39 patients were divided into two groups: one receiving tranexamic acid and the other not receiving it. Tranexamic acid was given in a dose of 10 mg/kg before the operation and twice thereafter, at 8-hour intervals. Total blood loss was smaller in the tranexamic acid group than in the control group. No thromboembolic complications were noticed. In a prospective, randomized study, 58 patients with hip arthroplasty and 39 patients with knee arthroplasty were divided into groups with postoperative closed-suction drainage and without drainage. There was no difference in healing of the wounds, postoperative blood transfusions, complications or range of motion. As a result of this study, the use of drains is no longer recommended. In a randomised study the effectiveness of a femoral nerve block (25 patients) was compared with other methods of pain control (24 patients) on the first postoperative day after total knee arthroplasty. The femoral block consisted of a single injection administered at patients´ bedside during the surgeon´s hospital rounds. Femoral block patients reported less pain and required half of the amount of oxycodone. Additional femoral block or continued epidural analgesia was required more frequently by the control group patients. Pain management with femoral blocks resulted in less work for nursing staff. In a retrospective study of 422 total hip and knee arthroplasty cases the C-reactive protein levels and clinical course were examined. After hip and knee arthroplasty the maximal C-reactive protein values are seen on the second and third postoperative days, after which the level decreases rapidly. There is no difference between patients with cemented or uncemented prostheses. Major postoperative complications may cause a further increase in C-reactive protein levels at one and two weeks. In-hospital and outpatient postoperative control radiographs of 200 hip and knee arthroplasties were reviewed retrospectively. If postoperative radiographs are of good quality, there seems to be no need for early repetitive radiographs. The quality and safety of follow-up is not compromised by limiting follow-up radiographs to those with clinical indications. Exposure of the patients and the staff to radiation is reduced. Reading of the radiographs by only the treating orthopaedic surgeon is enough. These factors may seem separate from each other, but linking them together may help the treating orthopaedic surgeon to adequate patient care strategy. Notable savings can be achieved.

Deuterium-carbon correlation in static oriented systems using DAPT - A windowless multiple pulse sequence

We present a new method for establishing correlation between deuterium and its attached carbon in a deuterated liquid crystal. The method is based on transfer of polarization using the DAPT pulse sequence proposed originally for two spin half nuclei, now extended to a spin-1 and a spin-1/2 nuclei. DAPT utilizes the evolution of magnetization of the spin pair under two blocks of phase shifted BLEW-12 pulses on one of the spins separated by a 90 degree pulse on the other spin. The method is easy to implement and does not need to satisfy matching conditions unlike the Hartmann-Hahn cross-polarization. Experimental results presented demonstrate the efficacy of the method.

A kinematic theory for radially foldable planar linkages

By using the algebraic locus of the coupler curve of a PRRP planar linkage, in this paper, a kinematic theory is developed for planar, radially foldable closed-loop linkages. This theory helps derive the previously invented building blocks, which consist of only two inter-connected angulated elements, for planar foldable structures. Furthermore, a special case of a circumferentially actuatable foldable linkage (which is different from the previously known cases) is derived from the theory, A quantitative description of some known and some new properties of planar foldable linkages, including the extent of foldability, shape-preservation of the interior polygons, multi-segmented assemblies and heterogeneous circumferential arrangemants, is also presented. The design equations derived here make the conception of even complex planar radially foldable linkages systematic and straightforward. Representative examples are presented to illustrate the usage of the design equations and the construction of prototypes. The current limitations and some possible extensions of the theory are also noted. (c) 2007, Elsevier Ltd. All ri-hts reserved.

Limiting the Extent of the RDN1 Heterochromatin Domain by a Silencing Barrier and Sir2 Protein Levels in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, transcriptional silencing occurs at the cryptic mating-type loci (HML and HMR), telomeres, and ribosomal DNA ( rDNA; RDN1). Silencing in the rDNA is unusual in that polymerase II (Pol II) promoters within RDN1 are repressed by Sir2 but not Sir3 or Sir4. rDNA silencing unidirectionally spreads leftward, but the mechanism of limiting its spreading is unclear. We searched for silencing barriers flanking the left end of RDN1 by using an established assay for detecting barriers to HMR silencing. Unexpectedly, the unique sequence immediately adjacent to RDN1, which overlaps a prominent cohesin binding site (CARL2), did not have appreciable barrier activity. Instead, a fragment located 2.4 kb to the left, containing a tRNA(Gln) gene and the Ty1 long terminal repeat, had robust barrier activity. The barrier activity was dependent on Pol III transcription of tRNA(Gln), the cohesin protein Smc1, and the SAS1 and Gcn5 histone acetyltransferases. The location of the barrier correlates with the detectable limit of rDNA silencing when SIR2 is overexpressed, where it blocks the spreading of rDNA heterochromatin. We propose a model in which normal Sir2 activity results in termination of silencing near the physical rDNA boundary, while tRNA(Gln) blocks silencing from spreading too far when nucleolar Sir2 pools become elevated.

Block-based feature detection and matching for mosaicing of camera-captured document images

In this paper, we present a new feature-based approach for mosaicing of camera-captured document images. A novel block-based scheme is employed to ensure that corners can be reliably detected over a wide range of images. 2-D discrete cosine transform is computed for image blocks defined around each of the detected corners and a small subset of the coefficients is used as a feature vector A 2-pass feature matching is performed to establish point correspondences from which the homography relating the input images could be computed. The algorithm is tested on a number of complex document images casually taken from a hand-held camera yielding convincing results.

Design of a climate-responsive BIPV research facility in Bangalore

This paper describes the design and erection of a climate-responsive Building Integrated Photovoltaic (BIPV) structure in Bangalore, (12.58 N, 77.38 E) in the state of Karnataka, India. Building Integrated Photovoltaics integrate solar panels as part of a building structure (roofs and walls) with an aim to achieve self-sufficiency in the operation and occupant-comfort energy requirements. A joint collaboration between the Centre for Sustainable Technologies, Indian Institute of Science (IISc) and Bharat Heavy Electricals Limited (BHEL) is setting up a 70,000 US$ facility for research in BIPV structures. The structure utilizes low energy building materials like Stabilized Mud Blocks (SMB) integrated with a PV roof. Numerous challenges were overcome in the design of the BIPV roof including mechanisms for natural thermal comfort in response to Bangalore's climatic conditions. The paper presents the challenges overcome in the design and construction of a low energy, climate-responsive BIPV structure.

Chemically Programmed Ultrahigh Density Two-Dimensional Semiconductor Superlattice Array

Designing an ultrahigh density linear superlattice array consisting of periodic blocks of different semiconductors in the strong confinement regime via a direct synthetic route remains an unachieved challenge in nanotechnology. We report a general synthesis route for the formulation of a large-area ultrahigh density superlattice array that involves adjoining multiple units of ZnS rods by prolate US particles at the tips. A single one-dimensional wire is 300-500 nm long and consists of periodic quantum wells with a barrier width of 5 nm provided by ZnS and a well width of 1-2 nm provided by CdS, defining a superlattice structure. The synthesis route allows for tailoring of ultranarrow laserlike emissions (fwhm approximate to 125 meV) originating from strong interwell energy dispersion along with control of the width, pitch, and registry of the superlattice assembly. Such an exceptional high-density superlattice array could form the basis of ultrahigh density memories in addition to offering opportunities for technological advancement in conventional heterojunction-based device applications.

A Concise Synthesis of Substituted Thiourea Derivatives in Aqueous Medium

An efficient method for the synthesis of symmetrical and unsymmetrical substituted thiourea derivatives by means of simple condensation between available building blocks such Lis airlines and carbon disulfide in aqueous medium is presented. This protocol works smoothly with aliphatic primary amines to afford various di- and trisubstituted thiourea derivatives. The present method is also useful ill synthesizing various substituted 2-mercapto imidazole heterocycles. This method proceeds through a xanthate (amino dithiol deivative) intermediate, unlike isothiocyanate as in all earlier known method.

Formal Verification of Full-Wave Rectifier: A Case Study

We present a case study of formal verification of full-wave rectifier for analog and mixed signal designs. We have used the Checkmate tool from CMU [1], which is a public domain formal verification tool for hybrid systems. Due to the restriction imposed by Checkmate it necessitates to make the changes in the Checkmate implementation to implement the complex and non-linear system. Full-wave rectifier has been implemented by using the Checkmate custom blocks and the Simulink blocks from MATLAB from Math works. After establishing the required changes in the Checkmate implementation we are able to efficiently verify, the safety properties of the full-wave rectifier.