Variety Of Applications (variety + of_application)

Distribution by Scientific Domains

Selected Abstracts

GPU-Based Nonlinear Ray Tracing

Daniel Weiskopf
In this paper, we present a mapping of nonlinear ray tracing to the GPU which avoids any data transfer back to main memory. The rendering process consists of the following parts: ray setup according to the camera parameters, ray integration, ray-object intersection, and local illumination. Bent rays are approximated by polygonal lines that are represented by textures. Ray integration is based on an iterative numerical solution of ordinary differential equations whose initial values are determined during ray setup. To improve the rendering performance, we propose acceleration techniques such as early ray termination and adaptive ray integration. Finally, we discuss a variety of applications that range from the visualization of dynamical systems to the general relativistic visualization in astrophysics and the rendering of the continuous refraction in media with varying density. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism [source]

Multimedia vectorization of floating-point MIN/MAX reductions

Aart J. C. Bik
Abstract Finding the minimum or maximum value in an array forms an important step in a variety of applications. This paper discusses vectorization schemes that take advantage of the streaming-SIMD-extensions in commonly used floating-point MIN and MAX reductions. Performance advantages are demonstrated with experimental results. Copyright 2006 John Wiley & Sons, Ltd. [source]

Improved Microcontact Printing of Proteins using Hydrophilic Thermoplastic Elastomers as Stamp Materials,

C. Trimbach
Recently, the microstructuring of biological species, such as proteins, using microcontact printing (,CP), has become very popular. Microstructuring of proteins is useful for a variety of applications, such as biosensors, controlled cell growth and adhesion and microarrays for bioanalytical detection. Here the authors investigated the microcontact printing of proteins using a hydrophilic thermoplastic elastomeric stamp material. The emphasis is placed on the quality of the printed patterns with respect to inking time and protein concentration in the ink. [source]

A Closer Look Inside Nanotubes: Pore Structure Evaluation of Anodized Alumina Templated Carbon Nanotube Membranes Through Adsorption and Permeability Studies

Georgios Pilatos
Abstract Although hollow nanostructures, such as nanotubes, represent a major portion of nanoscaled materials with a tremendously large application range, a detailed evaluation of their internal characteristics still remains elusive. Transmission electron microscopy is the most common analytical technique to examine the internal configuration of these structures, yet it can only provide evidence of a minimal portion of the overall material, thus, it cannot be accurately generalized. In the present paper, in addition to electron microscopy and other spot-size analysis methods (X-ray diffraction, Raman spectroscopy, etc.), a combination of techniques including adsorption, permeability, and relative permeability are employed in order to provide important insights into various crucial details of the overall internal surface and hollow-space characteristics of carbon nanotube (CNT) arrays and membranes. The CNT arrays are fabricated using anodized alumina as a template in a flow-through chemical vapor deposition (CVD) reactor. This is the first systematic approach for investigating the internal configuration of template-based CNT arrays in detail. Key findings are made for the customized optimization of the resulting nanotube membranes for a variety of applications, including separations, nanofluidics and nanoreactors, biological capturing and purification, and controlled drug delivery and release. [source]

Enhancement of Thermoelectric Figure-of-Merit by a Bulk Nanostructuring Approach

Yucheng Lan
Abstract Recently a significant figure-of-merit (ZT) improvement in the most-studied existing thermoelectric materials has been achieved by creating nanograins and nanostructures in the grains using the combination of high-energy ball milling and a direct-current-induced hot-press process. Thermoelectric transport measurements, coupled with microstructure studies and theoretical modeling, show that the ZT improvement is the result of low lattice thermal conductivity due to the increased phonon scattering by grain boundaries and structural defects. In this article, the synthesis process and the relationship between the microstructures and the thermoelectric properties of the nanostructured thermoelectric bulk materials with an enhanced ZT value are reviewed. It is expected that the nanostructured materials described here will be useful for a variety of applications such as waste heat recovery, solar energy conversion, and environmentally friendly refrigeration. [source]

Fabrication of Flexible Binary Amplitude Masks for Patterning on Highly Curved Surfaces

Audrey M. Bowen
Abstract This paper describes soft lithography methods that expand current fabrication capabilities by enabling high-throughput patterning on nonplanar substrates. These techniques exploit optically dense elastomeric mask elements embedded in a transparent poly(dimethylsiloxane) (PDMS) matrix by vacuum-assisted microfluidic patterning, UV,ozone-mediated irreversible sealing, and chemical etching. These protocols provide highly flexible photomasks exhibiting either positive- or negative-image contrasts, which serve as amplitude masks for large-area photolithographic patterning on a variety of curved (and planar) surfaces. When patterning on cylindrical surfaces, the developed masks do not experience significant pattern distortions. For substrates with 3D curvatures/geometries, however, the PDMS mask must undergo relatively large strains in order to make conformal contact. The new methods described in this report provide planar masks that can be patterned to compliantly compensate for both the displacements and distortions of features that result from stretching the mask to span the 3D geometry. To demonstrate this, a distortion-corrected grid pattern mask was fabricated and used in conjunction with a homemade inflation device to pattern an electrode mesh on a glass hemisphere with predictable registration and distortion compensation. The showcased mask fabrication processes are compatible with a broad range of substrates, illustrating the potential for development of complex lithographic patterns for a variety of applications in the realm of curved electronics (i.e., synthetic retinal implants and curved LED arrays) and wide field-of-view optics. [source]

1D and 3D Ionic Liquid,Aluminum Hydroxide Hybrids Prepared via an Ionothermal Process,

S. Park
Abstract Room-temperature ionic liquids (RTILs) are used as hierarchically multifunctional components by employing them not only as templates and co-solvents for fabricating nanostructured materials but also proton conductors for electrochemical devices. RTIL/aluminum hydroxide (RTIL,Al) hybrids containing various nanometer-sized shapes, including 1D nanorods with hexagonal tips, straight and curved nanofibers, nanofibers embedded in a porous network, and 3D octahedral-, polyhedral-, and angular spherical shapes are synthesized via a one-pot ionothermal process. The structures or shapes of the RTIL,Al hybrids are related to the anionic moieties, alkyl chain length of the RTILs, and the humidity during fabrication. In particular, the introduction of water molecules into the interface led to 3D isotropic growth of the hybrids by influencing intermolecular interactions between the RTILs and the building blocks. The shapes of the nanohybrids fabricated from RTILs containing short alkyl chains were dependent on the types of anions and on the level of humidity. These results indicate that the cooperative interactions between RTILs and aluminum hydroxides induces emerging shape-controlled hybrids. The shape-controlled nanohybrids show enhanced electrochemical properties compared to those of a conventional hybrid prepared by mixing RTILs and aluminum hydroxides, exhibiting tenfold or higher proton conductivity under anhydrous condition and thermal stability as a result of the continuous proton conduction channel and the one-pot-assembled nanoconfinement. This method is expected to be a useful technique for controlling the diverse shapes of nanometer-sized crystalline inorganic materials for a variety of applications, such as fuel cells, solar cells, rechargeable batteries, and biosensors. [source]

Directed Assembly of Polymer Blends Using Nanopatterned Templates

Ming Wei
The direct assembly of polymer blends on chemically functionalized surfaces is shown to produce a variety of nonuniform complex patterns. This method provides a powerful tool for easily producing nonuniform patterns in a rapid (30 s), one-step process with high specificity and selectivity for a variety of applications, such as nanolithography, polymeric optoelectronic devices, integrated circuits, and biosensors. [source]

The extended/generalized finite element method: An overview of the method and its applications

Thomas-Peter Fries
Abstract An overview of the extended/generalized finite element method (GEFM/XFEM) with emphasis on methodological issues is presented. This method enables the accurate approximation of solutions that involve jumps, kinks, singularities, and other locally non-smooth features within elements. This is achieved by enriching the polynomial approximation space of the classical finite element method. The GEFM/XFEM has shown its potential in a variety of applications that involve non-smooth solutions near interfaces: Among them are the simulation of cracks, shear bands, dislocations, solidification, and multi-field problems. Copyright 2010 John Wiley & Sons, Ltd. [source]

Free vibration of sandwich plates with laminated faces

W. X. Yuan
Description is given of the development of a spline finite strip method for predicting the natural frequencies and modes of conventional rectangular sandwich plates. The faceplates are treated as being classically thin and may be of composite laminated construction. The core is modelled as a three-dimensional body. Finite strip stiffness and mass properties are based on a displacement field which represents eight fundamental through-thickness displacements as a series of products of longitudinal B-spline functions and crosswise Lagrangian or Hermitian polynominal shape functions. The solution procedure utilizes the efficient superstrip concept in conjunction with the extended Sturm sequence-bisection approach. A variety of applications of the developed analysis capability is described which demonstrates the nature of the convergence of the finite strip predictions of natural frequencies and the close comparison of these predictions with available results in the literature, and also the use of the capability in parametric studies. Copyright 2002 John Wiley & Sons, Ltd. [source]

High Aspect-Ratio Cylindrical Nanopore Arrays and Their Use for Templating Titania Nanoposts,

O.-H. Park
Well-defined arrays of titania nanoposts are generated by using high aspect-ratio cylindrical nanopore templates. The simple and controllable fabrication scheme of the nanoporous templates makes them very attractive for creating well-defined nanostructures out of a variety of functional materials. The arrays of titania nanoposts can find a variety of applications such as photonic crystals, photocatalysts, and photovoltaics. [source]

Full-duplex analogue/digital data transmission using lasers coupled to GI fibre and its application

Masayoshi Kamiya
Abstract This paper describes a low-cost version of a full-duplex optical fibre analogue/digital data transmission link whose practical implementation is simplified by using a pair of laser diodes, each having a built-in photodiode for monitoring the laser output power, and its application to vibration test data transmission. The transmission link sends digital data of up to 9600 bps in one direction, and analogue data of DC to 100 kHz and image data specified by an NTSC colour video signal in the opposite direction, all at the same time through one GI optical fibre. Being simple in configuration and stable against noise, this type of link has a variety of applications within factory, home and offices. Copyright 2001 John Wiley & Sons, Ltd. [source]

Microarray-based DNA profiling to study genomic aberrations,

IUBMB LIFE, Issue 7 2008
Nic Waddell
Abstract High throughput microarrays were initially developed to analyse the expression of many RNA transcripts in parallel. The technology has since been adapted to a variety of applications, one of which is the analysis of the genome to study DNA dosage and sequence content. Advances in microarray fabrication and completion of large-scale genome sequencing projects have enabled the rapid development of affordable array-based methods for high-resolution genome-wide assessment of DNA alterations. This review will describe the evolution of microarray assays to study genomic aberrations and will highlight how they have enabled researchers to gain insight into the biology of human diseases and how they will benefit research in the future. 2008 IUBMB IUBMB Life, 60(7): 437,440, 2008 [source]

Mechanical behavior of carbon nanofibre-reinforced epoxy composites

Sohel Rana
Abstract Epoxy resins are widely used in a variety of applications because of their high chemical and corrosion resistance and good mechanical properties. But few types of epoxy resins are brittle and possess low toughness which makes them unsuitable for several structural applications. In this work, carbon nanofibres have been dispersed uniformly into the epoxy resin at a very low concentration (0.07 vol. %). Improvement of 98% in Young modulus, 24% in breaking stress and 144% in work of rupture was achieved in the best sample. The emphasis is on achieving uniform dispersion of carbon nanofibers into epoxy resin using a combination of techniques such as ultrasonication, use of solvent and surfactants. The fracture surfaces of the specimens were studied under scanning electron microscope to see the fracture mechanism of nanocomposites under tensile load and correlate it to the enhancement in their properties. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Between ends and fibers

C. Paul Bonnington
Abstract Let , be an infinite, locally finite, connected graph with distance function ,. Given a ray P in , and a constant C , 1, a vertex-sequence is said to be regulated by C if, for all n,,, never precedes xn on P, each vertex of P appears at most C times in the sequence, and . R. Halin (Math. Ann., 157, 1964, 125,137) defined two rays to be end-equivalent if they are joined by infinitely many pairwise-disjoint paths; the resulting equivalence classes are called ends. More recently H. A. Jung (Graph Structure Theory, Contemporary Mathematics, 147, 1993, 477,484) defined rays P and Q to be b-equivalent if there exist sequences and VQ regulated by some constant C , 1 such that for all n,,; he named the resulting equivalence classes b-fibers. Let denote the set of nondecreasing functions from into the set of positive real numbers. The relation (called f-equivalence) generalizes Jung's condition to . As f runs through , uncountably many equivalence relations are produced on the set of rays that are no finer than b -equivalence while, under specified conditions, are no coarser than end-equivalence. Indeed, for every , there exists an "end-defining function" that is unbounded and sublinear and such that implies that P and Q are end-equivalent. Say if there exists a sublinear function such that . The equivalence classes with respect to are called bundles. We pursue the notion of "initially metric" rays in relation to bundles, and show that in any bundle either all or none of its rays are initially metric. Furthermore, initially metric rays in the same bundle are end-equivalent. In the case that , contains translatable rays we give some sufficient conditions for every f -equivalence class to contain uncountably many g -equivalence classes (where ). We conclude with a variety of applications to infinite planar graphs. Among these, it is shown that two rays whose union is the boundary of an infinite face of an almost-transitive planar map are never bundle- equivalent. 2006 Wiley Periodicals, Inc. J Graph Theory 54: 125,153, 2007 [source]

MRI tissue characterization of experimental cerebral ischemia in rat

Hamid Soltanian-Zadeh PhD
Abstract Purpose To extend the ISODATA image segmentation method to characterize tissue damage in stroke, by generating an MRI score for each tissue that corresponds to its histological damage. Materials and Methods After preprocessing and segmentation (using ISODATA clustering), the proposed method scores tissue regions between 1 and 100. Score 1 is assigned to normal brain matter (white or gray matter), and score 100 to cerebrospinal fluid (CSF). Lesion zones are assigned a score based on their relative levels of similarities to normal brain matter and CSF. To evaluate the method, 15 rats were imaged by a 7T MRI system at one of three time points (acute, subacute, chronic) after MCA occlusion. Then they were killed and their brains were sliced and prepared for histological studies. MRI of two or three slices of each rat brain (using two DWI (b = 400, b = 800), one PDWI, one T2WI, and one T1WI) was performed, and an MRI score between 1 and 100 was determined for each region. Segmented regions were mapped onto the histology images and scored on a scale of 1,10 by an experienced pathologist. The MRI scores were validated by comparison with histology scores. To this end, correlation coefficients between the two scores (MRI and histology) were determined. Results Experimental results showed excellent correlations between MRI and histology scores at different time points. Depending on the reference tissue (gray matter or white matter) used in the standardization, the correlation coefficients ranged from 0.73 (P < 0.0001) to 0.78 (P < 0.0001) using the entire dataset, including acute, subacute, and chronic time points. This suggests that the proposed multiparametric approach accurately identified and characterized ischemic tissue in a rat model of cerebral ischemia at different stages of stroke evolution. Conclusion The proposed approach scores tissue regions and characterizes them using unsupervised clustering and multiparametric image analysis techniques. The method can be used for a variety of applications in the field of computer-aided diagnosis and treatment, including evaluation of response to treatment. For example, volume changes for different zones of the lesion over time (e.g., tissue recovery) can be evaluated. J. Magn. Reson. Imaging 2003;17:398,409. 2003 Wiley-Liss, Inc. [source]

Mimicking biological delivery through feedback-controlled drug release systems based on molecular imprinting

AICHE JOURNAL, Issue 6 2009
David R. Kryscio
Intelligent drug delivery systems (DDS) are able to rapidly detect a biological event and respond appropriately by releasing a therapeutic agent; thus, they are advantageous over their conventional counterparts. Molecular imprinting is a promising area that generates a polymeric network which can selectively recognize a desired analyte. This field has been studied for a variety of applications over a long period of time, but only recently has it been investigated for biomedical and pharmaceutical applications. Recent work in the area of molecularly imprinted polymers in drug delivery highlights the potential of these recognitive networks as environmentally responsive DDS that can ultimately lead to feedback controlled recognitive release systems. 2009 American Institute of Chemical Engineers AIChE J, 2009. [source]

Unified model for nonideal multicomponent molecular diffusion coefficients

AICHE JOURNAL, Issue 11 2007
Alana Leahy-Dios
Abstract Multicomponent diffusion is important in a variety of applications. In order to calculate diffusion flux, molecular diffusion coefficients are required, where fluid nonideality and the multicomponent nature of the mixture have a significant effect. A unified model for the calculation of diffusion coefficients of gas, liquid and supercritical states of nonpolar multicomponent mixtures is presented. A new correlation is proposed for the binary infinite dilution-diffusion coefficients. The generalized Vignes relation is used in multicomponent mixtures. Nonideality is rigorously described by the fugacity derivatives evaluated by the volume-translated Peng-Robinson equation of state. Predictions for highly nonideal gas and liquid multicomponent mixtures demonstrate the reliability of the proposed methodology. 2007 American Institute of Chemical Engineers AIChE J, 2007 [source]

Phosphothioated oligodeoxynucleotides induce nonspecific effects on neuronal cell adhesion in a growth substrate-dependent manner,

Eitan Okun
Abstract Synthetic phosphothioated (PTO) oligodeoxynucleotide (ODN) sequences are commonly used for a variety of applications that benefit from nuclease protection. The PTO modification is implemented mainly in antisense ODN, but also in ODN that were shown to activate members of the toll-like receptor (TLR) family such as TLR3 (poly-I:C), TLR8 (ssRNA), and TLR9 (CpG). Neurons are routinely plated on surfaces coated with either cationic substances such as poly-L-ornithine (PLO), polyethylenimine (PEI), poly-L-lysine or ECM components such as laminin, collagen, or fibronectin. We found that PTO-ODN aimed at activating TLR9 induces a non-TLR9-specific detachment phenotype in cortical neurons plated on either laminin or PEI, but not on PLO. This phenotype was correlated with decreased viability and was partially inhibited when caspase-3 was inhibited with Ac-DEVD-CMK. This finding suggests that the use of PTO-ODN can cause nonspecific effects on cell adhesion that could compromise interpretation of data from experiments using PTO-ODN. 2009 Wiley-Liss, Inc. [source]

Identification and characterisation of the E951 artificial food sweetener by vibrational spectroscopy and theoretical modelling

Niculina Peica
Abstract Aspartame (E951), a very well-known dipeptide sweetener, approximately 150,200 times sweeter than sugar, is widely used in a variety of applications, especially in soft drinks. A drawback of E951 is its relatively low stability at high pH values and at high temperatures, thereby limiting its use. The changes observed in the very strong bands from the 1600,1300 cm,1 spectral region, characteristic to the ,(CO) mode coupled with the NH bending mode, allows to establish the species present in the Raman and SERS solutions at different concentrations and pH values. More exactly, a molecule protonation at the amino group was detected on going from basic to acidic pH values. The DFT calculated geometry, harmonic vibrational modes and Raman scattering activities of E951 were in good agreement with the experimental data and helped establish its SERS behaviour on silver surfaces. According to the DFT calculations performed, E951 can give rise to an intramolecular hydrogen bonding network, with lengths in the same range as the hydrogen bonds in the peptide unit moieties. Copyright 2009 John Wiley & Sons, Ltd. [source]

13C-detected IPAP-INADEQUATE for simultaneous measurement of one-bond and long-range scalar or residual dipolar coupling constants

Lan Jin
Abstract The sensitivity of cryoprobes, which are rapidly becoming available, means that the measurement of coupling constants involving 13C, 13C pairs at the natural abundance of 13C can now, in principle, be done by using tens rather then hundreds of milligrams of compounds. However, a robust method that would yield reliable values of small long-range carbon--carbon coupling constants is still missing. In this Communication, we describe a novel 13C,detected incredible natural-abundance double-quantum transfer experiment (INADEQUATE) experiment for simultaneous correlation of one-bond and long-range 13C13C pairs and the measurement of both types of coupling constants in 13C natural abundance samples. This method yields accurate values of one-bond and long-range coupling constants by manipulation of pure phase in-phase (IP) and antiphase (AP) doublets, and is referred to as 13C-detected IPAP-INADEQUATE. It is illustrated by the measurement of interglycosidic 3JCCOC coupling constants in a disaccharide molecule providing important information about the conformation of the glycosidic linkage. Owing to the simplicity of INADEQUATE spectra the carbon,carbon coupling constants are particularly suitable for studies of partially oriented molecules through the measurement of carbon,carbon residual dipolar couplings (RDCs). An example of this approach is presented. We expect the method to find a variety of applications in the conformational analysis of small molecules, determination of diastereoisomers and enantiomers, and studies of molecules in aligned media. Copyright 2007 John Wiley & Sons, Ltd. [source]

A specially structured nonlinear integer resource allocation problem

Kurt M. Bretthauer
Abstract We present an algorithm for solving a specially structured nonlinear integer resource allocation problem. This problem was motivated by a capacity planning study done at a large Health Maintenance Organization in Texas. Specifically, we focus on a class of nonlinear resource allocation problems that involve the minimization of a convex function over one general convex constraint, a set of block diagonal convex constraints, and bounds on the integer variables. The continuous variable problem is also considered. The continuous problem is solved by taking advantage of the structure of the Karush-Kuhn-Tucker (KKT) conditions. This method for solving the continuous problem is then incorporated in a branch and bound algorithm to solve the integer problem. Various reoptimization results, multiplier bounding results, and heuristics are used to improve the efficiency of the algorithms. We show how the algorithms can be extended to obtain a globally optimal solution to the nonconvex version of the problem. We further show that the methods can be applied to problems in production planning and financial optimization. Extensive computational testing of the algorithms is reported for a variety of applications on continuous problems with up to 1,000,000 variables and integer problems with up to 1000 variables. 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 770,792, 2003. [source]

A hub covering model for cargo delivery systems

Pinar Z. Tan
Abstract The hub location problem appears in a variety of applications including airline systems, cargo delivery systems, and telecommunication network design. When we analyze the application areas separately, we observe that each area has its own characteristics. In this research we focus on cargo delivery systems. Our interviews with various cargo delivery firms operating in Turkey enabled us to determine the constraints, requirements, and criteria of the hub location problem specific to the cargo delivery sector. We present integer programming formulations and large-scale implementations of the models within Turkey. The results are compared with the current structure of a cargo delivery firm operating in Turkey. 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 49(1), 28,39 2007 [source]

Practical mathematical model to predict the performance of insulating packages

Seung-Jin Choi
Abstract Thermal insulation is used in a variety of applications to protect temperature-sensitive products from thermal damage. Several factors affect the performance of insulating packages. These factors include the packaging material, the geometry of the package, the geometry of the product, and the degree of contact between the product and the package. In this study, a comprehensive model which includes all of these factors was developed to predict the performance of the insulating package. First, an equation was derived for the calculation of the thermal resistance of a multilayered wall. The wall resistance was then used in a mathematical model which included the aforementioned factors. Basic heat transfer principles covering conduction, convection and radiation were applied to the model and the package heat penetration rate was calculated. Based on this model, several factors affecting the performance of the insulating package were discussed. Examples of the use of this model for ice requirement calculations were also included. Copyright 2007 John Wiley & Sons, Ltd. [source]

Patterned transparent zinc oxide films produced by sol,gel embossing

J. Rao
Abstract A low cost zinc oxide embossing technique is reported as a method of fabricating structures relevant to a variety of applications. A zinc based sol,gel material was prepared from zinc acetate [Zn(C2H3O2)2], monoethanolamine [H2NC2H4OH] and isopropanol. The sol,gel was cast into a polydimethylsiloxane (PDMS) mould a track design, placed in contact with the substrate and dried under vacuum at 70 C for 3 hours. The formed track pattern was further densified to provide a stable conductor film that retained the embossed shape. An optimum Zn sol,gel content of 0.6 M was identified. The embossed films had a transparency of greater than 83% in the visible region. The optical bandgap energy was evaluated to be 3.306 eV. The influence of ZnO sol,gel film synthesis and embossing parameters on the microstructure, morphology and optical transparency of fabricated structures is described. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

2005 Emil Thomas Kaiser Award

Ronald T. Raines
Abstract Collagen is the most abundant protein in animals. The conformational stability of the collagen triple helix is enhanced by the hydroxyl group of its prevalent (2S,4R)-4-hydroxyproline residues. For 25 years, the prevailing paradigm had been that this enhanced stability is due to hydrogen bonds mediated by bridging water molecules. We tested this hypothesis with synthetic collagen triple helices containing 4-fluoroproline residues. The results have unveiled a wealth of stereoelectronic effects that contribute markedly to the stability of collagen, as well as other proteins. This new understanding is leading to synthetic collagens for a variety of applications in biotechnology and biomedicine. [source]

Optimal linear LQG control over lossy networks without packet acknowledgment

Bruno Sinopoli
Abstract This paper is concerned with control applications over lossy data networks. Sensor data is transmitted to an estimation-control unit over a network, and control commands are issued to subsystems over the same network. Sensor and control packets may be randomly lost according to a Bernoulli process. In this context, the discrete-time linear quadratic Gaussian (LQG) optimal control problem is considered. It is known that in the scenario described above, and for protocols for which there is no acknowledgment of successful delivery of control packets (e.g. UDP-like protocols), the LQG optimal controller is in general nonlinear. However, the simplicity of a linear sub-optimal solution is attractive for a variety of applications. Accordingly, this paper characterizes the optimal linear static controller and compares its performance to the case when there is acknowledgment of delivery of packets (e.g. TCP-like protocols). Copyright 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

Network and service architecture for emerging services based on home sensor networks

Harish Viswanathan
Sensor networks in the home can enable a variety of applications such as home monitoring and control, home security, home energy management, and home health care. Current state-of-the-art solutions typically target a single sensor application and do not take advantage of the established infrastructure of the broadband service provider, such as a telco operator or cable provider. In this paper, we propose an alternative solution that provides a comprehensive and scalable service platform for multiple parallel home sensor applications, even from third party providers. We highlight the advantages that a broadband service provider holds for providing these emerging high margin services, and derive a suitable end-to-end network architecture. We describe the functions of each of the main components and some of their interfaces, and pay particular attention to one of the key technological challenges: the commissioning and management of the home sensor network. In particular, we describe a laboratory implementation that demonstrates the feasibility of automatic commissioning and remote management of the sensor network. 2009 Alcatel-Lucent. [source]

Synthesis and Reactivity of 6,7-dihydrogeranylazides: Reagents for Primary Azide Incorporation into Peptides and Subsequent Staudinger Ligation

Juhua Xu
Protein farnesyltransferase (PFTase) catalyzes the attachment of a geranylazide moiety to a peptide substrate, N -dansyl-GCVIA. Because geranylazide is actually a mixture of isomeric, interconverting primary and secondary azides, incorporation of this isoprenoid into peptides can potentially result in a corresponding mixture of prenylated peptides. Here, we first examined the reactivity of geranyl azide in a model Staudinger reaction and determined that a mixture of products is formed. We then describe the synthesis of 6,7-dihydrogeranylazide diphosphate and demonstrate that this compound allows exclusive incorporation of a primary azide into a peptide. The resulting azide-containing peptide was derivatized with a triphenylphosphine-based reagent to generate an O -alkyl imidate-linked product. Finally, we show, using a series of model reactions, that the Staudinger ligation frequently produces small amounts of O -alkyl imidate products in addition to the major amide-linked products. Thus, the alkoxyimidates we have observed as the exclusive products in the reactions of peptides containing prenylated azides also appear to be a common type of product formed using other azide-containing reactants, although at greatly reduced levels. This method for chemical modification of the C-terminus of a protein should be useful for a variety of applications in protein chemistry. [source]

En Route to Nanodevices of Polyoxometalate: Incorporating the Giant Nanoporous Molybdenum-Oxide based Wheels and Balls into Nanotubular Arrays

Lijuan Zhang Dr.
Layered tubes: The giant nanoporous molybdenum-oxide based polyoxometalates of the wheel and Keplerate type with unique features, which can be considered as the basis of a new type of nanochemistry and nanomaterials science and find a variety of applications, can be easily incorporated into nanotubular arrays with well defined wall thickness and aperture. [source]