Sample records for stereochemistry modulates stability

  1. Influence of Linkage Stereochemistry and Protecting Groups on Glycosidic Bond Stability of Sodium Cationized Glycosyl Phosphates (United States)

    Zhu, Y.; Yang, Zhihua; Rodgers, M. T.


    Energy-resolved collision-induced dissociation (ER-CID) experiments of sodium cationized glycosyl phosphate complexes, [GP x +Na]+, are performed to elucidate the effects of linkage stereochemistry (α versus β), the geometry of the leaving groups (1,2-cis versus 1,2-trans), and protecting groups (cyclic versus non-cyclic) on the stability of the glycosyl phosphate linkage via survival yield analyses. A four parameter logistic dynamic fitting model is used to determine CID50% values, which correspond to the level of rf excitation required to produce 50% dissociation of the precursor ion complexes. Present results suggest that dissociation of 1,2-trans [GP x +Na]+ occurs via a McLafferty-type rearrangement that is facilitated by a syn orientation of the leaving groups, whereas dissociation of 1,2-cis [GPx+Na]+ is more energetic as it involves the formation of an oxocarbenium ion intermediate. Thus, the C1-C2 configuration plays a major role in determining the stability/reactivity of glycosyl phosphate stereoisomers. For 1,2-cis anomers, the cyclic protecting groups at the C4 and C6 positions stabilize the glycosidic bond, whereas for 1,2-trans anomers, the cyclic protecting groups at the C4 and C6 positions tend to activate the glycosidic bond. The C3 O-benzyl (3 BnO) substituent is key to determining whether the sugar or phosphate moiety retains the sodium cation upon CID. For 1,2-cis anomers, the 3 BnO substituent weakens the glycosidic bond, whereas for 1,2-trans anomers, the 3 BnO substituent stabilizes the glycosidic bond. The C2 O-benzyl substituent does not significantly impact the glycosidic bond stability regardless of its orientation. [Figure not available: see fulltext.

  2. Mathematical stereochemistry

    CERN Document Server

    Fujita, Shinsaku


    Chirality and stereogenicity are closely related concepts and their differentiation and description is still a challenge in chemoinformatics. A new stereoisogram approach, developed by the author, is introduced in this book, providing a theoretical framework for mathematical aspects of modern stereochemistry. The discussion covers point-groups and permutation symmetry and exemplifies the concepts using organic molecules and inorganic complexes.


    African Journals Online (AJOL)

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    Synthesis, stereochemistry and antimicrobial activity of copper(II) and nickel(II) complexes. Bull. Chem. Soc. Ethiop. 2011, 25(3). 363 recorded in DMF using a Perkin-Elmer 575 spectrophotometer (USA). Nuclear magnetic ... ESR spectra of the complexes were obtained on a Varian E4-EPR spectrometer at about 9.4 GHz ...

  4. Stereochemistry basic concepts and applications

    CERN Document Server

    Nógrádi, M


    Stereochemistry: Basic Concepts and Applications is a three-chapter text that introduces the basic principles and concepts of stereochemistry, as well as its application to organic chemistry application.Chapter 1 describes first the stereochemistry of the ground state, specifically the configuration and conformation of organic compounds, as well as the most important methods for its investigation. This chapter also deals with the kinetics of conformational changes and provides an overview of the so-called ""applied stereochemistry"". Chapter 2 focuses on the analysis of the internal motions of

  5. The structure and stability of persistence modules

    CERN Document Server

    Chazal, Frédéric; Glisse, Marc; Oudot, Steve


    This book is a comprehensive treatment of the theory of persistence modules over the real line. It presents a set of mathematical tools to analyse the structure and to establish the stability of such modules, providing a sound mathematical framework for the study of persistence diagrams. Completely self-contained, this brief introduces the notion of persistence measure and makes extensive use of a new calculus of quiver representations to facilitate explicit computations. Appealing to both beginners and experts in the subject, The Structure and Stability of Persistence Modules provides a purely algebraic presentation of persistence, and thus complements the existing literature, which focuses mainly on topological and algorithmic aspects.

  6. Matlab Stability and Control Toolbox: Trim and Static Stability Module (United States)

    Crespo, Luis G.; Kenny, Sean P.


    This paper presents the technical background of the Trim and Static module of the Matlab Stability and Control Toolbox. This module performs a low-fidelity stability and control assessment of an aircraft model for a set of flight critical conditions. This is attained by determining if the control authority available for trim is sufficient and if the static stability characteristics are adequate. These conditions can be selected from a prescribed set or can be specified to meet particular requirements. The prescribed set of conditions includes horizontal flight, take-off rotation, landing flare, steady roll, steady turn and pull-up/ push-over flight, for which several operating conditions can be specified. A mathematical model was developed allowing for six-dimensional trim, adjustable inertial properties, asymmetric vehicle layouts, arbitrary number of engines, multi-axial thrust vectoring, engine(s)-out conditions, crosswind and gyroscopic effects.

  7. using stereochemistry models in teaching organic compounds

    African Journals Online (AJOL)

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    Overall findings of the study showed among others that the control group (Chart Model) experienced more problems in organic nomenclature than the experimental group. (Stereochemistry Model); the treatment had significant effect: students taught using. Stereochemistry Models performed better than those taught using ...

  8. Modulational stability and dark solitons in periodic quadratic nonlinear media

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole


    We show that stable dark solitons exist in quadratic nonlinear media with periodic linear and nonlinear susceptibilities. We investigate the modulational stability of plane waves in such systems, a necessary condition for stable dark solitons....

  9. Pasteur-The Harbinger of Stereochemistry-Louis Pasteur, Tartaric ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 1. Pasteur - The Harbinger of Stereochemistry - Louis Pasteur, Tartaric Acid and Stereochemistry. Gopalpur Nagendrappa. General Article Volume 12 Issue 1 January 2007 pp 38-48 ...

  10. MATLAB Stability and Control Toolbox Trim and Static Stability Module (United States)

    Kenny, Sean P.; Crespo, Luis


    MATLAB Stability and Control Toolbox (MASCOT) utilizes geometric, aerodynamic, and inertial inputs to calculate air vehicle stability in a variety of critical flight conditions. The code is based on fundamental, non-linear equations of motion and is able to translate results into a qualitative, graphical scale useful to the non-expert. MASCOT was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental nonlinear equations of motion, MASCOT then calculates vehicle trim and static stability data for the desired flight condition(s). Available flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind, and sideslip, plus three take-off rotation conditions. Results are displayed through a unique graphical interface developed to provide the non-stability and control expert conceptual design engineer a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. If desired, the user can also examine the detailed, quantitative results.

  11. Stereochemistry and rearrangement reactions of hydroxylignanolactones. (United States)

    Raffaelli, Barbara; Pohjoispää, Monika; Hase, Tapio; Cardin, Christine J; Gan, Yu; Wähälä, Kristiina


    Various conflicting data on the rearrangement and absolute stereochemistry of hydroxylignano-9,7'-lactones are resolved using 18O labeled compounds, also confirmed by an X-ray analysis of a pure lignano-9,7'-lactone enantiomer, obtained for the first time. Under NaH/DMF rearrangement conditions a silyl protected hydroxylignano-9,9'-lactone underwent an unexpected silyl migration.

  12. Optmized stability of a modulated driver in a plasma wakefield

    CERN Document Server

    Martorelli, Roberto


    We analyze the transverse stability for a configuration of multiple gaussian bunches subject to the self-generated plasma wakefield. Through a semi-analytical approach we first study the equilibrium configuration for the modulated beam and then we investigate the evolution of the equilibrium configuration due to the emittance-driven expansion of the beam front that results in a rigid backward shift. The rear-directed shift brings the modulated beam out of the equilibrium, with the possibility for some of the bunch particles to be lost with a consequent deterioration of the driver. We look therefore for the proper position of the single bunches that maximize the stability without severely affecting the accelerating field behind the driver. We then compare the results with 3D PIC simulations.

  13. MHD stability module for the National Transport Code Collaboration Library (United States)

    Pletzer, A.; Manickam, J.; Jardin, S. C.; McCune, D.; Ludescher, Ch.; Klasky, S.; Randerson, L.


    There is a need to provide numerical tools to the fusion community that are robust, portable, easy to use, documented, and reviewed by independent peers. A web site ( where modules can be freely downloaded has been set up for that purpose [Status of the NTCC Modules Library (D McCune)]. The existence of such a library is in addition motivated by the increasing demand for programs that can be plugged into large packages with minimal effort. In particular, there has been some requests to make MHD stability codes such as the PEST, which are capable of simulating large scale plasma phenomena, available at the NTCC module library. Progress on the work to convert PEST to satisfy the NTCC module standards is presented. The resulting, new PEST interface is a collection of subroutines, which initialize, modify and extract data. Dynamic memory allocation is introduced to minimize memory requirements and allow for multiple runs. Embedded graphics routines are disabled and dependence on native binary files replaced by portable NetCDF files. To illustrate the flexibility of the module approach, numerical results obtained by integrating PEST-3, the mapping code DMAP and the equilibrium JSOLVER modules into a C++ and Java environment with remote database connectivity are presented.

  14. The Stereochemistry of Biochemical Molecules: A Subject to Revisit (United States)

    Centelles, Josep J.; Imperial, Santiago


    Although Fischer's convention for stereoisomers is useful for simple molecules, the stereochemistry of complex biochemical molecules is often poorly indicated in textbooks. This article reports on errors in stereochemistry of complex hydrosoluble vitamin B12 molecule. Twenty-five popular biochemistry textbooks were examined for their treatment of…

  15. Relative stability of radicals derived from artemisinin: A semiempirical and DFT study (United States)

    Arantes, C.; de Araujo, M. T.; Taranto, A. G.; de M. Carneiro, J. W.

    The semiempirical AM1 and PM3 methods, as well as the density functional (DFT/B3LYP) approach using the 6-31g(d) basis set, were employed to calculate the relative stability of intermediate radicals derived from artemisinin, a sesquiterpene lactone having an endoperoxide bridge that is essential for its antimalarial activity. The compounds studied have their nonperoxidic oxygen atom of the trioxane ring and/or the carbonyl group replaced by a CH2 unit. Relative stabilities were calculated by means of isodesmic equations using artemisinin as reference. It was found that replacement of oxygen atoms decreases the relative stability of the anionic radical intermediates. In contrast, for compounds with inverted stereochemistry the intermediate radicals were found to be more stable than those with the artemisinin-like stereochemistry. These relative stabilities may modulate the antimalarial potency. Radicals centered on carbon are always more stable than the corresponding radicals centered on oxygen.

  16. Absolute Configuration of (-)-2-(4-Hydroxyphenyl)propionic acid: Stereochemistry of Soy Isoflavone Metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mihyang; Han, Jaehong [Chung-Ang Univ., Seoul (Korea, Republic of)


    We have elucidated stereochemistry of (-)-2-HPPA. Determination of (R)-2-HPPA stereochemistry also provided stereochemical information of genistein metabolism. Considering the stereochemistry of 2-HPPA, the precursor of (R)-2-HPPA should be (R)-6'-hydroxy-O-DMA. Besides, it is clear that only (S)-dihydrogenistein is the possible precursor of (R)-6'-hydroxy-O-DMA. Therefore, genistein metabolism is suggested to follow the same stereochemical pathway like daidzein. Biotransformation of natural products by human intestinal bacteria has recently drawn a significant interest, due to the emerging strong correlation between gut microbiota and human health. Microbial metabolism of natural products by intestinal bacteria in small intestine and colon proceeds the phase I and II xenobiotic metabolisms in the liver. The metabolites were found to exhibit different biological activities, and affect human etiology. For example, many beneficial effects of dietary polyphenols in human health are attributed to the microbial metabolites produced by intestinal bacteria and the modulation of gut microbiota composition.

  17. Asymptotic Stability of Semi-Markov Modulated Jump Diffusions

    Directory of Open Access Journals (Sweden)

    Amogh Deshpande


    Full Text Available We consider the class of semi-Markov modulated jump diffusions (sMMJDs whose operator turns out to be an integro-partial differential operator. We find conditions under which the solutions of this class of switching jump-diffusion processes are almost surely exponentially stable and moment exponentially stable. We also provide conditions that imply almost sure convergence of the trivial solution when the moment exponential stability of the trivial solution is guaranteed. We further investigate and determine the conditions under which the trivial solution of the sMMJD-perturbed nonlinear system of differential equations /=( is almost surely exponentially stable. It is observed that for a one-dimensional state space, a linear unstable system of differential equations when stabilized just by the addition of the jump part of an sMMJD process does not get destabilized by any addition of a Brownian motion. However, in a state space of dimension at least two, we show that a corresponding nonlinear system of differential equations stabilized by jumps gets destabilized by addition of Brownian motion.

  18. Analysis of Pulse Modulated Control Systems (Ⅲ) Stability of Systems with Pulse Frequency Modulation and Systems with Combined Pulse Frequency and Pulse Width Modulation




    Sufficient conditions for finite pulse stability of interconnected systems with combined pulse frequency and pulse width modulation are developed in this paper using a direct method. The stability criteria established provide upper bounds on the number of pulses emitted by each modulator. The results are also applicable to those systems which contain a finite number of pulse frequency modulators and a finite number of combined pulse frequency and pulse width modulators

  19. Opsin stability and folding: modulation by phospholipid bicelles. (United States)

    McKibbin, Craig; Farmer, Nicola A; Jeans, Chris; Reeves, Philip J; Khorana, H Gobind; Wallace, B A; Edwards, Patricia C; Villa, Claudio; Booth, Paula J


    Integral membrane proteins do not fare well when extracted from biological membranes and are unstable or lose activity in detergents commonly used for structure and function investigations. We show that phospholipid bicelles provide a valuable means of preserving alpha-helical membrane proteins in vitro by supplying a soluble lipid bilayer fragment. Both 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/3-[(cholamidopropyl)dimethyl-ammonio]-1-propane sulfonate (Chaps) and DMPC/l-alpha-1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) bicelles dramatically increase the stability of the mammalian vision receptor rhodopsin as well as its apoprotein, opsin. Opsin is particularly unstable in detergent solution but can be directly purified into DMPC/Chaps. We show that opsin can also be directly purified in DMPC/DHPC bicelles to give correctly folded functional opsin, as shown by the ability to regenerate rhodopsin to approximately 70% yield. These well-characterised DMPC/DHPC bicelles enable us to probe the influence of bicelle properties on opsin stability. These bicelles are thought to provide DMPC bilayer fragments with most DHPC capping the bilayer edge, giving a soluble bilayer disc. Opsin stability is shown to be modulated by the q value, the ratio of DMPC to DHPC, which reflects changes in the bicelle size and, thus, proportion of DMPC bilayer present. The observed changes in stability also correlate with loss of opsin secondary structure as determined by synchrotron far-UV circular dichroism spectroscopy; the most stable bicelle results in the least helix loss. The inclusion of Chaps rather than DHPC in the DMPC/Chaps bicelles, however, imparts the greatest stability. This suggests that it is not just the DMPC bilayer fragment in the bicelles that stabilises the protein, but that Chaps provides additional stability either through direct interaction with the protein or by altering the DMPC/Chaps bilayer properties within the bicelle. The significant stability

  20. Modulation of i-motif thermodynamic stability by the introduction of UNA (unlocked nucleic acid) monomers

    DEFF Research Database (Denmark)

    Pasternak, Anna; Wengel, Jesper


    The influence of acyclic RNA derivatives, UNA (unlocked nucleic acid) monomers, on i-DNA thermodynamic stability has been investigated. The 22 nt human telomeric fragment was chosen as the model sequence for stability studies. UNA monomers modulate i-motif stability in a position-depending manner...

  1. A new approach to codeword stabilized quantum codes using the algebraic structure of modules


    Santiago, Douglas Frederico Guimarães; Otoni, Geraldo Samuel Sena


    In this work, we study the Codeword Stabilized Quantum Codes (CWS codes) a generalization of the stabilizers quantum codes using a new approach, the algebraic structure of modules, a generalization of linear spaces. We show then a new result that relates CWS codes with stabilizer codes generalizing results in the literature.

  2. Ca2+ and Mg2+ modulate conformational dynamics and stability of downstream regulatory element antagonist modulator (United States)

    Pham, Khoa; Dhulipala, Gangadhar; Gonzalez, Walter G; Gerstman, Bernard S; Regmi, Chola; Chapagain, Prem P; Miksovska, Jaroslava


    Downstream Regulatory Element Antagonist Modulator (DREAM) belongs to the family of neuronal calcium sensors (NCS) that transduce the intracellular changes in Ca2+ concentration into a variety of responses including gene expression, regulation of Kv channel activity, and calcium homeostasis. Despite the significant sequence and structural similarities with other NCS members, DREAM shows several features unique among NCS such as formation of a tetramer in the apo-state, and interactions with various intracellular biomacromolecules including DNA, presenilin, Kv channels, and calmodulin. Here we use spectroscopic techniques in combination with molecular dynamics simulation to study conformational changes induced by Ca2+/Mg2+ association to DREAM. Our data indicate a minor impact of Ca2+ association on the overall structure of the N- and C-terminal domains, although Ca2+ binding decreases the conformational heterogeneity as evident from the decrease in the fluorescence lifetime distribution in the Ca2+ bound forms of the protein. Time-resolved fluorescence data indicate that Ca2+binding triggers a conformational transition that is characterized by more efficient quenching of Trp residue. The unfolding of DREAM occurs through an partially unfolded intermediate that is stabilized by Ca2+ association to EF-hand 3 and EF-hand 4. The native state is stabilized with respect to the partially unfolded state only in the presence of both Ca2+ and Mg2+ suggesting that, under physiological conditions, Ca2+ free DREAM exhibits a high conformational flexibility that may facilitate its physiological functions. PMID:25627705

  3. The reliability and stability of multijunction amorphous silicon PV modules

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, D.E. [Solarex, Newtown, PA (United States)


    Solarex is developing a manufacturing process for the commercial production of 8 ft{sup 2} multijunction amorphous silicon (a-Si) PV modules starting in 1996. The device structure used in these multijunction modules is: glass/textured tin oxide/p-i-n/p-i-n/ZnO/Al/EVA/Tedlar where the back junction of the tandem structure contains an amorphous silicon germanium alloy. As an interim step, 4 ft{sup 2} multijunction modules have been fabricated in a pilot production mode over the last several months. The distribution of initial conversion efficiencies for an engineering run of 67 modules (4 ft{sup 2}) is shown. Measurements recently performed at NREL indicate that the actual efficiencies are about 5% higher than those shown, and thus exhibit an average initial conversion efficiency of about 9.5%. The data indicates that the process is relatively robust since there were no modules with initial efficiencies less than 7.5%.

  4. Improving the Operational Stability of PBDTTTz-4 Polymer Solar Cells Modules by Electrode Modification

    DEFF Research Database (Denmark)

    Roth, Bérenger; Benatto, Gisele Alves dos Reis; Corazza, Michael


    is a good candidate for upscaling. Stability measurements following the ISOS standards are used to compare the lifetime of the different modules. In all tests but one, the carbon modules are less stable. The higher stability of AgNW is attributed to the removal of the PEDOT:PSS in the front electrode....... Finally during indoor light tests, a new degradation phenomenon is observed where bubbles are formed inside the modules contrary to previous reports of bubble formation by thermal expansion of trapped gas inside the barrier....

  5. Control of Foxp3 stability through modulation of TET activity (United States)

    Yue, Xiaojing; Trifari, Sara; Äijö, Tarmo; Tsagaratou, Ageliki; Pastor, William A.; Zepeda-Martínez, Jorge A.; Lio, Chan-Wang J.; Li, Xiang; Huang, Yun; Vijayanand, Pandurangan; Lähdesmäki, Harri


    Ten-eleven translocation (TET) enzymes oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine and other oxidized methylcytosines, intermediates in DNA demethylation. In this study, we examine the role of TET proteins in regulating Foxp3, a transcription factor essential for the development and function of regulatory T cells (T reg cells), a distinct lineage of CD4+ T cells that prevent autoimmunity and maintain immune homeostasis. We show that during T reg cell development in the thymus, TET proteins mediate the loss of 5mC in T reg cell–specific hypomethylated regions, including CNS1 and CNS2, intronic cis-regulatory elements in the Foxp3 locus. Similar to CNS2-deficient T reg cells, the stability of Foxp3 expression is markedly compromised in T reg cells from Tet2/Tet3 double-deficient mice. Vitamin C potentiates TET activity and acts through Tet2/Tet3 to increase the stability of Foxp3 expression in TGF-β–induced T reg cells. Our data suggest that targeting TET enzymes with small molecule activators such as vitamin C might increase induced T reg cell efficacy. PMID:26903244

  6. From Cell to Module: Fabrication and Long-term Stability of Dye-sensitized Solar Cells (United States)

    Nursam, N. M.; Hidayat, J.; Muliani, L.; Anggraeni, P. N.; Retnaningsih, L.; Idayanti, N.


    Dye-sensitized solar cell (DSSC), which has been firstly developed by Graetzel et al back in 1991, has attracted a considerable interest since its discovery. However, two of the main challenges that the DSSC technology will have to overcome towards commercialization involve device scale-up and long-term stability. In our group, the fabrication technology of DSSC has been developed from laboratory to module scale over the past few years, nevertheless, the long-term stability has still became a major concern. In this contribution, the long-term DSSC performance in relation to their scale-up from cell to module is investigated. The photoelectrode of the DSSCs were fabricated using nanocrystalline titanium dioxide materials that were subsequently sensitized using ruthenium-based dye. Additionally, TiCl4 pre- and post-treatment were carried out to enhance the overall device efficiency. When fabricated as cells, the DSSC prototypes showed relatively stable performance during repeated tests over three months. In order to increase the output power of the solar cells, the DSSCs were then connected in a Z-type series connection to obtain sub-module panels. The DSSC sub-modules exhibit poor stability, particularly as indicated by the significant decrease in the short circuit current (ISC ). Herein, the effect of photoelectrode and sealant materials as well as module design are investigated, highlighting their profound influence upon the DSSC efficiency and long-term stability.

  7. Drogue Parachute Effects on the Orion Crew Module Stability (United States)

    Aubuchon, Vanessa V.; Owens, D. Bruce; Fremaux, C. Michael


    A forced oscillation test of the Orion Crew Module (CM) was conducted in the Langley 20-Foot Vertical Spin Tunnel. The objective of the test was to quantify the rate damping characteristics of the CM-drogue chute system. Numerous configurations were tested to measure the influence of the chutes on the CM dynamic aerodynamics and, conversely, the influence of the CM on drogue performance. Results show that the CM-drogue system is well-damped at all combinations of frequency, amplitude, and Strouhal number. The wake of the CM significantly reduces the drogue chute riser line force, and the drogues have little upstream influence on the CM aerodynamics. These results are being used to improve simulation model fidelity of CM flight with drogues deployed, which has been identified by the project as key to a successful Orion Critical Design Review.

  8. SOS: A Mnemonic for the Stereochemistry of Glucose (United States)

    Starkey, Ronald


    The mnemonic SOS (Same, Opposite, Same) can be helpful to recall the stereochemistry in either D-glucose or L-glucose. It refers to the configurations of C-2, C-3, and C-4 relative to that of C-5 in an aldohexose. Same and Opposite refer to either the R or S configuration or to the relative positions of the OH groups on the Fischer projection structural formula. The SOS mnemonic can help to reinforce that gluco specifies the relative configurations of stereocenters in the molecule.

  9. Protein stability and dynamics modulation: the case of human frataxin.

    Directory of Open Access Journals (Sweden)

    Ernesto A Roman

    Full Text Available Frataxin (FXN is an α/β protein that plays an essential role in iron homeostasis. Apparently, the function of human FXN (hFXN depends on the cooperative formation of crucial interactions between helix α1, helix α2, and the C-terminal region (CTR of the protein. In this work we quantitatively explore these relationships using a purified recombinant fragment hFXN90-195. This variant shows the hydrodynamic behavior expected for a monomeric globular domain. Circular dichroism, fluorescence, and NMR spectroscopies show that hFXN90-195 presents native-like secondary and tertiary structure. However, chemical and temperature induced denaturation show that CTR truncation significantly destabilizes the overall hFXN fold. Accordingly, limited proteolysis experiments suggest that the native-state dynamics of hFXN90-195 and hFXN90-210 are indeed different, being the former form much more sensitive to the protease at specific sites. The overall folding dynamics of hFXN fold was further explored with structure-based protein folding simulations. These suggest that the native ensemble of hFXN can be decomposed in at least two substates, one with consolidation of the CTR and the other without consolidation of the CTR. Explicit-solvent all atom simulations identify some of the proteolytic target sites as flexible regions of the protein. We propose that the local unfolding of CTR may be a critical step for the global unfolding of hFXN, and that modulation of the CTR interactions may strongly affect hFXN physiological function.

  10. An inter-laboratory stability study of roll-to-roll coated flexible polymer solar modules

    DEFF Research Database (Denmark)

    Gevorgyan, Suren; Medford, Andrew James; Bundgaard, Eva


    O (nanoparticulate, thin film) were employed as electron transport layers. The devices were all tested at Risø DTU and the functional devices were subjected to an inter-laboratory study involving the performance and the stability of modules over time in the dark, under light soaking and outdoor conditions. 24...

  11. Overview of Orion Crew Module and Launch Abort Vehicle Dynamic Stability (United States)

    Owens, Donald B.; Aibicjpm. Vamessa V.


    With the retirement of the Space Shuttle, NASA is designing a new spacecraft, called Orion, to fly astronauts to low earth orbit and beyond. Characterization of the dynamic stability of the Orion spacecraft is important for the design of the spacecraft and trajectory construction. Dynamic stability affects the stability and control of the Orion Crew Module during re-entry, especially below Mach = 2.0 and including flight under the drogues. The Launch Abort Vehicle is affected by dynamic stability as well, especially during the re-orientation and heatshield forward segments of the flight. The dynamic stability was assessed using the forced oscillation technique, free-to-oscillate, ballistic range, and sub-scale free-flight tests. All of the test techniques demonstrated that in heatshield-forward flight the Crew Module and Launch Abort Vehicle are dynamically unstable in a significant portion of their flight trajectory. This paper will provide a brief overview of the Orion dynamic aero program and a high-level summary of the dynamic stability characteristics of the Orion spacecraft.

  12. Alteration of Polyketide Stereochemistry from anti to syn by a Ketoreductase Domain Exchange in a Type I Modular Polyketide Synthase Subunit

    Energy Technology Data Exchange (ETDEWEB)

    Eng, Clara H.; Yuzawa, Satoshi; Wang, George; Baidoo, Edward E. K.; Katz, Leonard; Keasling, Jay D.


    Polyketide natural products have broad applications in medicine. Exploiting the modular nature of polyketide synthases to alter stereospecificity is an attractive strategy for obtaining natural product analogues with altered pharmaceutical properties. The purpose of research is to demonstrate that by retaining a dimerization element present in LipPks1+TE, we are able to use a ketoreductase domain exchange to alter α-methyl group stereochemistry with unprecedented retention of activity and simultaneously achieve a novel alteration of polyketide product stereochemistry from anti to syn. The substrate promiscuity of LipPks1+TE further provided a unique opportunity to investigate the substrate dependence of ketoreductase activity in a polyketide synthase module context.

  13. A high-performance liquid chromatography with circular dichroism detector for determination of stereochemistry of 6, 9-oxygen bridge dibenzocyclooctadiene lignans from kadsura coccinea. (United States)

    Zhu, Hui; Xu, Liang; Yang, Shi-Lin; Li, He-Ran


    The stereochemistry of two 6, 9-oxygen bridge dibenzocyclooctadiene lignans from Kadsura coccinea, are difficult to separate and very unstable. The present study was designed to develop a high-performance liquid chromatography using circular dichroism detection for the analysis of the stereochemistry. A new 6, 9-oxygen bridge dibenzocyclooctadiene lignans named Kadsulignan Q was firstly found with an S-biphenyl configuration. The other compound was identified as Kadsulignan L with an R- biphenyl configuration. In order to obtain kinetic data on their reversible interconversion, the stability was measured at different deuterated solvents such as deuterated methanol, deuterated chloroform and deuterated dimethylsulfoxide. The lignans were more unstable and converted more easily in deuterated methanol than in deuterated chloroform and deuterated dimethylsulfoxide. Copyright © 2015 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  14. Lyapunov's stability and operational margin of grid-connected photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, C.; Amaratunga, G. [Cambridge Univ., Cambridge (United Kingdom). Dept. of Engineering


    Due to better feed-in tariffs or subsidies offered by electricity system operators worldwide, photovoltaic (PV) installations are expected to increase rapidly, especially in Germany, Spain, California, Arizona, Texas, Japan, India, and China. Much research has focused on the development of low-power single-phase grid-connected photovoltaic AC-modules as it has the advantage of being more flexible and scalable, while featuring a low initial investment cost, making it a more compelling option for faster penetration in deregulated electricity supply environments. This paper presented an analysis of photovoltaic power generation based on Lyapunov's theorems. In order to establish energy functions that assess the stability of solutions and define safe regions of operation, the characteristics of the photovoltaic module and the power conditioning unit were analyzed. The paper provided an introduction to photovoltaic installations and then described the power conditioning unit for the AC-module that consisted of a DC-AC-DC converter with a high-frequency transformer and a full-bridge inverter. The control of power transfer was achieved through a current-feedback loop and a current-mode-control voltage source inverter. Stability analyses based on Lyapunov's theorems on stability and the stability margin were also presented. Last, numerical examples were provided in order to illustrate the validity of the theory. It was concluded that the module was capable of retaining stability if the state variables were kept within a region defined by an energy boundary. 9 refs., 9 figs.

  15. Analysis of data reliability and stability in HR-SDN communication module (United States)

    Choi, Dong-Hee; Shin, Jin-Chul; Park, Hong-Seong


    Profibus is open industrial communication system for wide range of applications in manufacturing and process automation. In Profibus, FDL service use to need hard real-time system. In these systems required data reliability and stability and real-time feature. Profibus fieldbus networks used in many industrial fields because of it supports real-time industrial communication. So we analyze of data reliability and stabilization in profibus network. In this paper, there was to a station for communication which uses FDL from in the communication module which is used a data transfer possibility at once, and from communication period (ex. 10ms) it analyzed the system effect which it follows in transmission lag occurrence element and a data transfer error ratio it analyzed. Like this analytical result it led and there were from transmission for reliability and data stability they confirmed to HR-SDN communication modules and a guarantee yes or no. In this paper, we try to analysis of transmission delay ability for satisfaction data reliability and stability in specific system, which requested real-time feature. And, we analysis system reconstruction time and data delay time according to data/token packet loss. Packet-error occur physical layer in Profibus. As a result of above analysis, we propose method of enhancement of reliability in system which requested system reliability and stability. And, we confirm proposed method.

  16. Modulation of protein stability and aggregation properties by surface charge engineering. (United States)

    Raghunathan, Govindan; Sokalingam, Sriram; Soundrarajan, Nagasundarapandian; Madan, Bharat; Munussami, Ganapathiraman; Lee, Sun-Gu


    An attempt to alter protein surface charges through traditional protein engineering approaches often affects the native protein structure significantly and induces misfolding. This limitation is a major hindrance in modulating protein properties through surface charge variations. In this study, as a strategy to overcome such a limitation, we attempted to co-introduce stabilizing mutations that can neutralize the destabilizing effect of protein surface charge variation. Two sets of rational mutations were designed; one to increase the number of surface charged amino acids and the other to decrease the number of surface charged amino acids by mutating surface polar uncharged amino acids and charged amino acids, respectively. These two sets of mutations were introduced into Green Fluorescent Protein (GFP) together with or without stabilizing mutations. The co-introduction of stabilizing mutations along with mutations for surface charge modification allowed us to obtain functionally active protein variants (s-GFP(+15-17) and s-GFP(+5-6)). When the protein properties such as fluorescent activity, folding rate and kinetic stability were assessed, we found the possibility that the protein stability can be modulated independently of activity and folding by engineering protein surface charges. The aggregation properties of GFP could also be altered through the surface charge engineering.

  17. Microneedles with intrinsic immunoadjuvant properties: microfabrication, protein stability, and modulated release. (United States)

    Andrianov, Alexander K; Marin, Alexander; DeCollibus, Daniel P


    Intradermal immunization using microneedles requires compatible immunoadjuvant system. To address this challenge, we investigated microneedles coated with polyphosphazene polyelectrolyte, which served both as microfabrication material and an immunoadjuvant compound. Coated microneedles were fabricated by depositing formulations containing Poly[di(carboxylatophenoxy)phosphazene], PCPP, on metal shafts, and their physico-chemical characterization was conducted. Microfabrication of PCPP-coated microneedles exhibited strong dependence on protein-PCPP interactions in solutions and allowed for high efficiency of protein encapsulation. 70°C thermal inactivation studies demonstrated a remarkable increase in functional stability of protein in coated microneedles compared to solution formulation. A potential for modulation of protein release from coated microneedles has been demonstrated through ionic complexation of PCPP with small ions. Microneedles containing PCPP coatings provide improved protein stability, modulated release, and protein-friendly microfabrication process.

  18. Top-down modulation in human visual cortex predicts the stability of a perceptual illusion (United States)

    Meindertsma, Thomas; Hillebrand, Arjan; van Dijk, Bob W.; Lamme, Victor A. F.; Donner, Tobias H.


    Conscious perception sometimes fluctuates strongly, even when the sensory input is constant. For example, in motion-induced blindness (MIB), a salient visual target surrounded by a moving pattern suddenly disappears from perception, only to reappear after some variable time. Whereas such changes of perception result from fluctuations of neural activity, mounting evidence suggests that the perceptual changes, in turn, may also cause modulations of activity in several brain areas, including visual cortex. In this study, we asked whether these latter modulations might affect the subsequent dynamics of perception. We used magnetoencephalography (MEG) to measure modulations in cortical population activity during MIB. We observed a transient, retinotopically widespread modulation of beta (12–30 Hz)-frequency power over visual cortex that was closely linked to the time of subjects' behavioral report of the target disappearance. This beta modulation was a top-down signal, decoupled from both the physical stimulus properties and the motor response but contingent on the behavioral relevance of the perceptual change. Critically, the modulation amplitude predicted the duration of the subsequent target disappearance. We propose that the transformation of the perceptual change into a report triggers a top-down mechanism that stabilizes the newly selected perceptual interpretation. PMID:25411458

  19. The application of encapsulation material stability data to photovoltaic module life assessment (United States)

    Coulbert, C. D.


    For any piece of hardware that degrades when subject to environmental and application stresses, the route or sequence that describes the degradation process may be summarized in terms of six key words: LOADS, RESPONSE, CHANGE, DAMAGE, FAILURE, and PENALTY. Applied to photovoltaic modules, these six factors form the core outline of an expanded failure analysis matrix for unifying and integrating relevant material degradation data and analyses. An important feature of this approach is the deliberate differentiation between factors such as CHANGE, DAMAGE, and FAILURE. The application of this outline to materials degradation research facilitates the distinction between quantifying material property changes and quantifying module damage or power loss with their economic consequences. The approach recommended for relating material stability data to photovoltaic module life is to use the degree of DAMAGE to (1) optical coupling, (2) encapsulant package integrity, (3) PV circuit integrity or (4) electrical isolation as the quantitative criterion for assessing module potential service life rather than simply using module power loss.

  20. Stereochemistry of 10-sulfoxidation catalyzed by a soluble delta9 desaturase

    Energy Technology Data Exchange (ETDEWEB)

    Tremblay, A.E.; Shanklin, J.; Tan, N.; Whittle, E.; Hodgson, D. J.; Dawson, B.; Buist, P. H.


    The stereochemistry of castor stearoyl-ACP 9 desaturase-mediated 10-sulfoxidation has been determined. This was accomplished by 19F NMR analysis of a fluorine-tagged product, 18-fluoro-10-thiastearoyl ACP S-oxide, in combination with a chiral solvating agent, (R)-AMA. Sulfoxidation proceeds with the same stereoselectivity as hydrogen removal from the parent stearoyl substrate. These data validate the use of thia probes to determine the stereochemistry and cryptoregiochemistry of desaturase-mediated oxidations.

  1. Performance Stabilization of CdTe PV Modules using Bias and Light

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, T. J.; Deceglie, M. G.; Marion, B.; Kurtz, S. R.


    Reversible performance changes due to light exposure frustrate repeatable performance measurements on CdTe PV modules. It is common to use extended light-exposure to ensure that measurements are representative of outdoor performance. We quantify the extent to which such a light-exposed state depends on module temperature and consider bias in the dark to aid in stabilization. We evaluate the use of dark forward bias to bring about a performance state equivalent to that obtained with light exposure, and to maintain a light-exposed state prior to STC performance measurement. Our results indicate that the most promising method for measuring a light-exposed state is to use light exposure at controlled temperature followed by prompt STC measurement with a repeatable time interval between exposure and the STC measurement.

  2. Outdoor Operational Stability of Indium-Free Flexible Polymer Solar Modules Over 1 Year Studied in India, Holland, and Denmark

    DEFF Research Database (Denmark)

    Angmo, Dechan; Sommeling, Paul M.; Gupta, Ritu


    /PEDOT:PSS/ZnO/P3HT:PCBM/PEDOT:PSS/Ag grid) were prepared in two successive generations and evaluated for outdoor operational stability according to the test protocols laid out by the International Summit on OPV stability (ISOS-3). The modules (70–100 cm2 active area) were encapsulated between two sheets of low...

  3. Accurate stereochemistry for two related 22,26-epiminocholestene derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Vega-Baez, José Luis; Sandoval-Ramírez, Jesús; Meza-Reyes, Socorro; Montiel-Smith, Sara; Gómez-Calvario, Victor [Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, San Manuel, 72000 Puebla, Pue. (Mexico); Bernès, Sylvain, E-mail: [DEP Facultad de Ciencias Químicas, UANL, Guerrero y Progreso S/N, Col. Treviño, 64570 Monterrey, NL (Mexico); Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, San Manuel, 72000 Puebla, Pue. (Mexico)


    Regioselective opening of ring E of solasodine under various conditions afforded (25R)-22,26-epimino@@cholesta-5,22(N)-di@@ene-3β,16β-diyl diacetate (previously known as 3,16-diacetyl pseudosolasodine B), C{sub 31}H{sub 47}NO{sub 4}, or (22S,25R)-16β-hydr@@oxy-22,26-epimino@@cholesta-5-en-3β-yl acetate (a derivative of the naturally occurring alkaloid oblonginine), C{sub 29}H{sub 47}NO{sub 3}. In both cases, the reactions are carried out with retention of chirality at the C16, C20 and C25 stereogenic centers, which are found to be S, S and R, respectively. Although pseudosolasodine was synthesized 50 years ago, these accurate assignments clarify some controversial points about the actual stereochemistry for these alkaloids. This is of particular importance in the case of oblonginine, since this compound is currently under consideration for the treatment of aphasia arising from apoplexy; the present study defines a diastereoisomerically pure compound for pharmacological studies.

  4. Experimental study on stabilizing range extension of diamagnetic levitation under modulated magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Chow, T C S; Wong, P L; Liu, K P, E-mail:, E-mail:, E-mail: [Manufacturing Engineering and Engineering Management Department, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)


    The real energy-free levitation exists with the help of diamagnetic material. Its ultra-high sensitivity to force is particularly attractive to micro/nano force sensing. A key parameter: Levitation Stabilizing Local Range, LR (allowable moving range of the floater) is critical to the load and self-rotating performance. Besides, larger LR reduces the energy loss due to the eddy current and has greater application potential. Recently, an idea of extending the LR by a modulating coil array has been validated using numerical simulation. This paper takes the next move to carry out an experimental study on the shape effect of stacked coil arrays with different currents on LR.

  5. Long Lifetime DC-Link Voltage Stabilization Module for Smart Grid Application

    DEFF Research Database (Denmark)

    Wang, Huai; Chung, Henry; Liu, Wenchao


    Power converters enable efficient and flexible control and conversion of electric energy among different smart grid players (i.e. producers, energy storage systems, and loads). One of the expected features of smart grid is that it will be more reliable compared to conventional grid. However, power...... converters are one kind of the lifetime limiting components applied in smart grid. One of the major causes is the malfunction of electrolytic capacitors (E-Caps) which are widely used for stabilizing the dc-link voltage in various types of power converters applied in smart grid. A dc-link module is therefore...

  6. Non-local effects of point mutations on the stability of a protein module (United States)

    Chwastyk, Mateusz; Vera, Andrés M.; Galera-Prat, Albert; Gunnoo, Melissabye; Thompson, Damien; Carrión-Vázquez, Mariano; Cieplak, Marek


    We combine experimental and theoretical methods to assess the effect of a set of point mutations on c7A, a highly mechanostable type I cohesin module from scaffoldin CipA from Clostridium thermocellum. We propose a novel robust and computationally expedient theoretical method to determine the effects of point mutations on protein structure and stability. We use all-atom simulations to predict structural shifts with respect to the native protein and then analyze the mutants using a coarse-grained model. We examine transitions in contacts between residues and find that changes in the contact map usually involve a non-local component that can extend up to 50 Å. We have identified mutations that may lead to a substantial increase in mechanical and thermodynamic stabilities by making systematic substitutions into alanine and phenylalanine in c7A. Experimental measurements of the mechanical stability and circular dichroism data agree qualitatively with the predictions provided the thermal stability is calculated using only the contacts within the secondary structures.

  7. Coordinated sumoylation and ubiquitination modulate EGF induced EGR1 expression and stability.

    Directory of Open Access Journals (Sweden)

    Arcangela Gabriella Manente

    Full Text Available Human early growth response-1 (EGR1 is a member of the zing-finger family of transcription factors induced by a range of molecular and environmental stimuli including epidermal growth factor (EGF. In a recently published paper we demonstrated that integrin/EGFR cross-talk was required for Egr1 expression through activation of the Erk1/2 and PI3K/Akt/Forkhead pathways. EGR1 activity and stability can be influenced by many different post-translational modifications such as acetylation, phosphorylation, ubiquitination and the recently discovered sumoylation. The aim of this work was to assess the influence of sumoylation on EGF induced Egr1 expression and/or stability.We modulated the expression of proteins involved in the sumoylation process in ECV304 cells by transient transfection and evaluated Egr1 expression in response to EGF treatment at mRNA and protein levels.We demonstrated that in ECV304 cells Egr1 was transiently induced upon EGF treatment and a fraction of the endogenous protein was sumoylated. Moreover, SUMO-1/Ubc9 over-expression stabilized EGF induced ERK1/2 phosphorylation and increased Egr1 gene transcription. Conversely, in SUMO-1/Ubc9 transfected cells, EGR1 protein levels were strongly reduced. Data obtained from protein expression and ubiquitination analysis, in the presence of the proteasome inhibitor MG132, suggested that upon EGF stimuli EGR1 sumoylation enhanced its turnover, increasing ubiquitination and proteasome mediated degradation.Here we demonstrate that SUMO-1 modification improving EGR1 ubiquitination is involved in the modulation of its stability upon EGF mediated induction.

  8. Dynamic head-neck stabilization and modulation with perturbation bandwidth investigated using a multisegment neuromuscular model. (United States)

    Happee, Riender; de Bruijn, Edo; Forbes, Patrick A; van der Helm, Frans C T


    The human head-neck system requires continuous stabilization in the presence of gravity and trunk motion. We investigated contributions of the vestibulocollic reflex (VCR), the cervicocollic reflex (CCR), and neck muscle co-contraction to head-in-space and head-on-trunk stabilization, and investigated modulation of the stabilization strategy with the frequency content of trunk perturbations and the presence of visual feedback. We developed a multisegment cervical spine model where reflex gains (VCR and CCR) and neck muscle co-contraction were estimated by fitting the model to the response of young healthy subjects, seated and exposed to anterior-posterior trunk motion, with frequency content from 0.3 up to 1, 2, 4 and 8Hz, with and without visual feedback. The VCR contributed to head-in-space stabilization with a strong reduction of head rotation (1Hz). The CCR contributed to head-on-trunk stabilization with a reduction of head rotation and head translation relative to the trunk (strategies employed during low bandwidth perturbations most effectively reduced head rotation and head relative displacement up to 3Hz while control strategies employed during high bandwidth perturbations reduced head global translation between 1 and 4Hz. This indicates a shift from minimizing head-on-trunk rotation and translation during low bandwidth perturbations to minimizing head-in-space translation during high bandwidth perturbations. Presence of visual feedback had limited effects suggesting increased usage of vestibular feedback. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  9. Edge sealing for low cost stability enhancement of roll-to-roll processed flexible polymer solar cell modules

    DEFF Research Database (Denmark)

    Tanenbaum, David M.; Dam, Henrik Friis; Rösch, R.


    Fully roll-to-roll processed polymer solar cell modules were prepared, characterized, and laminated. Cell modules were cut from the roll and matched pairs were selected, one module with exposed cut edges, the other laminated again with the same materials and adhesive sealing fully around the cut...... edges. The edge sealing rim was 10 mm wide. Cell modules were characterized by periodic measurements of IV curves over extended periods in a variety of conditions, as well as by a variety of spatial imaging techniques. Data show significant stability benefits of the edge sealing process. The results...

  10. Stabilizing and Modulating Color by Copigmentation: Insights from Theory and Experiment. (United States)

    Trouillas, Patrick; Sancho-García, Juan C; De Freitas, Victor; Gierschner, Johannes; Otyepka, Michal; Dangles, Olivier


    Natural anthocyanin pigments/dyes and phenolic copigments/co-dyes form noncovalent complexes, which stabilize and modulate (in particular blue, violet, and red) colors in flowers, berries, and food products derived from them (including wines, jams, purees, and syrups). This noncovalent association and their electronic and optical implications constitute the copigmentation phenomenon. Over the past decade, experimental and theoretical studies have enabled a molecular understanding of copigmentation. This review revisits this phenomenon to provide a comprehensive description of the nature of binding (the dispersion and electrostatic components of π-π stacking, the hydrophobic effect, and possible hydrogen-bonding between pigment and copigment) and of spectral modifications occurring in copigmentation complexes, in which charge transfer plays an important role. Particular attention is paid to applications of copigmentation in food chemistry.

  11. Enhanced exo-inulinase activity and stability by fusion of an inulin-binding module. (United States)

    Zhou, Shun-Hua; Liu, Yuan; Zhao, Yu-Juan; Chi, Zhe; Chi, Zhen-Ming; Liu, Guang-Lei


    In this study, an inulin-binding module from Bacillus macerans was successfully fused to an exo-inulinase from Kluyveromyces marxianus, creating a hybrid functional enzyme. The recombinant exo-inulinase (rINU), the hybrid enzyme (rINUIBM), and the recombinant inulin-binding module (rIBM) were, respectively, heterologously expressed and biochemically characterized. It was found that both the inulinase activity and the catalytic efficiency (k cat/K m(app)) of the rINUIBM were considerably higher than those of rINU. Though the rINU and the rINUIBM shared the same optimum pH of 4.5, the optimum temperature of the rINUIBM (60 °C) was 5 °C higher than that of the rINU. Notably, the fused IBM significantly enhanced both the pH stability and the thermostability of the rINUIBM, suggesting that the rINUIBM obtained would have more extensive potential applications. Furthermore, the fusion of the IBM could substantially improve the inulin-binding capability of the rINUIBM, which was consistent with the determination of the K m(app). This meant that the fused IBM could play a critical role in the recognition of polysaccharides and enhanced the hydrolase activity of the associated inulinase by increasing enzyme-substrate proximity. Besides, the extra supplement of the independent non-catalytic rIBM could also improve the inulinase activity of the rINU. However, this improvement was much better in case of the fusion. Consequently, the IBM could be designated as a multifunctional domain that was responsible for the activity enhancement, the stabilization, and the substrate binding of the rINUIBM. All these features obtained in this study make the rINUIBM become an attractive candidate for an efficient inulin hydrolysis.

  12. Lumbopelvic Core Stabilization Exercise and Pain Modulation Among Individuals with Chronic Nonspecific Low Back Pain. (United States)

    Paungmali, Aatit; Joseph, Leonard H; Sitilertpisan, Patraporn; Pirunsan, Ubon; Uthaikhup, Sureeporn


    Lumbopelvic stabilization training (LPST) may provide therapeutic benefits on pain modulation in chronic nonspecific low back pain conditions. This study aimed to examine the effects of LPST on pain threshold and pain intensity in comparison with the passive automated cycling intervention and control intervention among patients with chronic nonspecific low back pain. A within-subject, repeated-measures, crossover randomized controlled design was conducted among 25 participants (7 males and 18 females) with chronic nonspecific low back pain. All the participants received 3 different types of experimental interventions, which included LPST, the passive automated cycling intervention, and the control intervention randomly, with 48 hours between the sessions. The pressure pain threshold (PPT), hot-cold pain threshold, and pain intensity were estimated before and after the interventions. Repeated-measures analysis of variance showed that LPST provided therapeutic effects as it improved the PPT beyond the placebo and control interventions (P < 0.01). The pain intensity under the LPST condition was significantly better than that under the passive automated cycling intervention and controlled intervention (P < 0.001). Heat pain threshold under the LPST condition also showed a significant trend of improvement beyond the control (P < 0.05), but no significant effects on cold pain threshold were evident. Lumbopelvic stabilization training may provide therapeutic effects by inducing pain modulation through an improvement in the pain threshold and reduction in pain intensity. LPST may be considered as part of the management programs for treatment of chronic low back pain. © 2017 World Institute of Pain.

  13. Host-Guest Assembly of a Molecular Reporter with Chiral Cyanohydrins for Assignment of Absolute Stereochemistry. (United States)

    Gholami, Hadi; Anyika, Mercy; Zhang, Jun; Vasileiou, Chrysoula; Borhan, Babak


    The absolute stereochemistry of cyanohydrins, derived from ketones and aldehydes, is obtained routinely, in a microscale and derivatization-free manner, upon their complexation with Zn-MAPOL, a zincated porphyrin host with a binding pocket comprised of a biphenol core. The host-guest complex leads to observable exciton-coupled circular dichroism (ECCD), the sign of which is easily correlated to the absolute stereochemistry of the bound cyanohydrin. A working model, based on the ECCD signal of cyanohydrins with known configuration, is proposed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A single mutation in the envelope protein modulates flavivirus antigenicity, stability, and pathogenesis.

    Directory of Open Access Journals (Sweden)

    Leslie Goo


    Full Text Available The structural flexibility or 'breathing' of the envelope (E protein of flaviviruses allows virions to sample an ensemble of conformations at equilibrium. The molecular basis and functional consequences of virus conformational dynamics are poorly understood. Here, we identified a single mutation at residue 198 (T198F of the West Nile virus (WNV E protein domain I-II hinge that regulates virus breathing. The T198F mutation resulted in a ~70-fold increase in sensitivity to neutralization by a monoclonal antibody targeting a cryptic epitope in the fusion loop. Increased exposure of this otherwise poorly accessible fusion loop epitope was accompanied by reduced virus stability in solution at physiological temperatures. Introduction of a mutation at the analogous residue of dengue virus (DENV, but not Zika virus (ZIKV, E protein also increased accessibility of the cryptic fusion loop epitope and decreased virus stability in solution, suggesting that this residue modulates the structural ensembles sampled by distinct flaviviruses at equilibrium in a context dependent manner. Although the T198F mutation did not substantially impair WNV growth kinetics in vitro, studies in mice revealed attenuation of WNV T198F infection. Overall, our study provides insight into the molecular basis and the in vitro and in vivo consequences of flavivirus breathing.

  15. Effects of cerium removal from glass on photovoltaic module performance and stability (United States)

    Kempe, Michael D.; Moricone, Thomas; Kilkenny, Matt


    Photovoltaic modules are exposed to extremely harsh conditions of heat, humidity, high voltage, mechanical stress, thermal cycling and ultraviolet (UV) radiation. The current qualification tests (e.g. IEC 61215) do not require sufficient UV exposure to evaluate lifespans of 30 years. Recently, photovoltaic panel manufacturers have been using glass that does not contain Cerium. This has the advantage of providing about 1.3% to 1.8% more photon transmission but potentially at the expense of long term stability. The additional transmission of light in the 300 nm to 340 nm range can cause delamination to occur about 3.8 times faster. Similarly, UV radiation will cause polymeric encapsulants, such as ethylene vinyl-acetate (EVA), to turn yellow faster losing photon transmission. Silicones do not suffer from light induced degradation as hydrocarbon based polymers do, therefore if silicone encapsulants are used, a 1.6% to 1.9% increase in photon transmission can be obtained from removal of Ce from glass, with no tradeoff in long term stability. Additionally antimony can be added to non-Ce containing glass to further improve photon transmission (principally in the IR range) by an additional 0.4% to 0.7%; however, this does not significantly affect UV transmission so the same UV induced reliability concerns will still exist with common hydrocarbon-based encapsulants.

  16. Plug-in module acceleration feedback control for fast steering mirror-based beam stabilization systems (United States)

    Deng, Chao; Ren, Wei; Mao, Yao; Ren, Ge


    A plug-in module acceleration feedback control (Plug-In AFC) strategy based on the disturbance observer (DOB) principle is proposed for charge-coupled device (CCD)-based fast steering mirror (FSM) stabilization systems. In classical FSM tracking systems, dual-loop control (DLC), including velocity feedback and position feedback, is usually utilized to enhance the closed-loop performance. Due to the mechanical resonance of the system and CCD time delay, the closed-loop bandwidth is severely restricted. To solve this problem, cascade acceleration feedback control (AFC), which is a kind of high-precision robust control method, is introduced to strengthen the disturbance rejection property. However, in practical applications, it is difficult to realize an integral algorithm in an acceleration controller to compensate for the quadratic differential contained in the FSM acceleration model, resulting in a challenging controller design and a limited improvement. To optimize the acceleration feedback framework in the FSM system, different from the cascade AFC, the accelerometers are used to construct DOB to compensate for the platform vibrations directly. The acceleration nested loop can be plugged into the velocity loop without changing the system stability, and the controller design is quite simple. A series of comparative experimental results demonstrate that the disturbance rejection property of the CCD-based FSM can be effectively improved by the proposed approach.

  17. Photochemical transformation. 35. Stereochemistry of electron transfer from photoexcited aromatic rings to carbon-chlorine bonds. Syn stereochemistry of migration in photo-Wagner-Meerwein rearrangements

    Energy Technology Data Exchange (ETDEWEB)

    Cristol, S.J.; Seapy, D.G.; Aeling, E.O.


    Studies have been conducted on the ground-state and excited-state solvolyses of the isomeric 7,8-dichloro derivatives of benzonaphthobicyclo(2.2.2)octadiene and benzoveratrobicyclo(2.2.2)octadiene. The silver ion assisted ground-state reactions proceed, as anticipated, with clean anti-stereochemistry (inversion at the migration terminus) reflected in the Wagner-Meerwein rearranged solvolysis products. Unlike the previously reported observations that excitation transfer from a photoexcited benzene ring to a ..beta..-carbon-chlorine bond requires anti-stereochemistry, electron transfer from excited naphthalene or veratrole rings occurs to both syn and anti carbon-chlorine bonds, although that to the latter is preferred. The results are consistent with an electron-transfer process to give a zwitterionic biradical and are rationalized by the Weller equation. Separation of chloride ion from the presumed zwitterionic biradical is accompanied by ''Wagner-Meerwein'' rearrangement but is predominately syn, rather than anti as in the ground state. The rearrangement stereochemistry is consistent with the idea that, in the principal photochemical process, migration with retention of configuration is concerted with the loss of chloride ion. 3 tables.

  18. Interlaboratory outdoor stability studies of flexible roll-to-roll coated organic photovoltaic modules: Stability over 10,000 h

    DEFF Research Database (Denmark)

    Gevorgyan, Suren; Madsen, Morten Vesterager; Dam, Henrik Friis


    This work attempts to reveal the comparability issues related to outdoor testing procedures of organic photovoltaic (OPV) modules via studies of inter-laboratory long-term outdoor measurements of roll-to-roll coated flexible OPV modules (P3HT:PCBM, inverted architecture) in different geographic...... and measurement setups on the comparability of test results are analyzed. A strong link between the device temperature and performance is revealed, which is ascribed to the reaction of PEDOT:PSS layer with water. The estimation of the true performance of the modules by accommodation of variations in testing...

  19. Using NMR to Probe the Regio- and Stereochemistry of the Hydration of 1-Hexene (United States)

    Saba, Shahrokh; Clarke, Donald D.; Iwanoski, Christa; Lobasso, Thomas


    This undergraduate organic laboratory experiment complements previously described and popular experiments on hydration of 1-hexene where students experimentally establish the Markovnikov regioselectivity of alkene hydration. In this experiment, students explore not only the regiochemistry but also the stereochemistry of 1-hexene hydration and…

  20. A Modulator-Induced Defect-Formation Strategy to Hierarchically Porous Metal-Organic Frameworks with High Stability. (United States)

    Cai, Guorui; Jiang, Hai-Long


    The pore size enlargement and structural stability have been recognized as two crucial targets, which are rarely achieved together, in the development of metal-organic frameworks (MOFs). Herein, we have developed a versatile modulator-induced defect-formation strategy, in the presence of monocarboxylic acid as a modulator and an insufficient amount of organic ligand, successfully realizing the controllable synthesis of hierarchically porous MOFs (HP-MOFs) with high stability and tailorable pore characters. Remarkably, the integration of high stability and large mesoporous property enables these HP-MOFs to be important porous platforms for applications involving large molecules, especially in catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Disulphide bridges of phospholipase C of Chlamydomonas reinhardtii modulates lipid interaction and dimer stability.

    Directory of Open Access Journals (Sweden)

    Mayanka Awasthi

    Full Text Available BACKGROUND: Phospholipase C (PLC is an enzyme that plays pivotal role in a number of signaling cascades. These are active in the plasma membrane and triggers cellular responses by catalyzing the hydrolysis of membrane phospholipids and thereby generating the secondary messengers. Phosphatidylinositol-PLC (PI-PLC specifically interacts with phosphoinositide and/or phosphoinositol and catalyzes specific cleavage of sn-3- phosphodiester bond. Several isoforms of PLC are known to form and function as dimer but very little is known about the molecular basis of the dimerization and its importance in the lipid interaction. PRINCIPAL FINDINGS: We herein report that, the disruption of disulphide bond of a novel PI-specific PLC of C. reinhardtii (CrPLC can modulate its interaction affinity with a set of phospholipids and also the stability of its dimer. CrPLC was found to form a mixture of higher oligomeric states with monomer and dimer as major species. Dimer adduct of CrPLC disappeared in the presence of DTT, which suggested the involvement of disulphide bond(s in CrPLC oligomerization. Dimer-monomer equilibrium studies with the isolated fractions of CrPLC monomer and dimer supported the involvement of covalent forces in the dimerization of CrPLC. A disulphide bridge was found to be responsible for the dimerization and Cys7 seems to be involved in the formation of the disulphide bond. This crucial disulphide bond also modulated the lipid affinity of CrPLC. Oligomers of CrPLC were also captured in in vivo condition. CrPLC was mainly found to be localized in the plasma membrane of the cell. The cell surface localization of CrPLC may have significant implication in the downstream regulatory function of CrPLC. SIGNIFICANCE: This study helps in establishing the role of CrPLC (or similar proteins in the quaternary structure of the molecule its affinities during lipid interactions.

  2. Reinforcement learning modulates the stability of cognitive control settings for object selection

    Directory of Open Access Journals (Sweden)

    Anthony William Sali


    Full Text Available Cognitive flexibility reflects both a trait that reliably differs between individuals and a state that can fluctuate moment-to-moment. Whether individuals can undergo persistent changes in cognitive flexibility as a result of reward learning is less understood. Here, we investigated whether reinforcing a periodic shift in an object selection strategy can make an individual more prone to switch strategies in a subsequent unrelated task. Participants completed two different choice tasks in which they selected one of four objects in an attempt to obtain a hidden reward on each trial. During a training phase, objects were defined by color. Participants received either consistent reward contingencies in which one color was more often rewarded, or contingencies in which the color that was more often rewarded changed periodically and without warning. Following the training phase, all participants completed a test phase in which reward contingencies were defined by spatial location and the location that was more often rewarded remained constant across the entire task. Those participants who received inconsistent contingencies during training continued to make more variable selections during the test phase in comparison to those who received the consistent training. Furthermore, a difference in the likelihood to switch selections on a trial-by-trial basis emerged between training groups: participants who received consistent contingencies during training were less likely to switch object selections following an unrewarded trial and more likely to repeat a selection following reward. Our findings provide evidence that the extent to which priority shifting is reinforced modulates the stability of cognitive control settings in a persistent manner, such that individuals become generally more or less prone to shifting priorities in the future.

  3. Measuring modules for the research of compensators of reactive power with voltage stabilization in MATLAB (United States)

    Vlasayevsky, Stanislav; Klimash, Stepan; Klimash, Vladimir


    A set of mathematical modules was developed for evaluation the energy performance in the research of electrical systems and complexes in the MatLab. In the electrotechnical library SimPowerSystems of the MatLab software, there are no measuring modules of energy coefficients characterizing the quality of electricity and the energy efficiency of electrical apparatus. Modules are designed to calculate energy coefficients characterizing the quality of electricity (current distortion and voltage distortion) and energy efficiency indicators (power factor and efficiency) are presented. There are described the methods and principles of building the modules. The detailed schemes of modules built on the elements of the Simulink Library are presented, in this connection, these modules are compatible with mathematical models of electrical systems and complexes in the MatLab. Also there are presented the results of the testing of the developed modules and the results of their verification on the schemes that have analytical expressions of energy indicators.

  4. Role of Modulators in Controlling the Colloidal Stability and Polydispersity of the UiO-66 Metal–Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Morris, William; Wang, Shunzhi; Cho, David; Auyeung, Evelyn [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States; Li, Peng; Farha, Omar K. [Department of Chemistry, King Abdulaziz University, Jeddah 21589, Saudi Arabia; Mirkin, Chad A. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States


    Nanoscale UiO-66 Zr6(OH)4O4(C8O4H4)6 has been synthesized with a series of carboxylic acid modulators, R-COOH (where R = H, CH3, CF3, and CHCl2). The phase purity and size of each MOF was confirmed by powder X-ray diffraction, BET surface area analysis, and scanning transmission electron microscopy (STEM). Size control of UiO-66 crystals from 20 nm to over 1 μm was achieved, and confirmed by STEM. The colloidal stability of each MOF was evaluated by dynamic light scattering and was found to be highly dependent on the modulator conditions utilized in the synthesis, with both lower pKa and higher acid concentration resulting in more stable structures. Furthermore, STEM was carried out on both colloidally stable samples and those that exhibited a large degree of aggregation, which allowed for visualization of the different degrees of dispersion of the samples. The use of modulators at higher concentrations and with lower pKas leads to the formation of more defects, as a consequence of terephthalic acid ligands being replaced by modulator molecules, thereby enhancing the colloidal stability of the UiO-66 nanoparticles. These findings could have a significant impact on nanoscale MOF material syntheses and applications, especially in the areas of catalysis and drug delivery.

  5. Cp* Iridium Complexes Give Catalytic Alkane Hydroxylation with Retention of Stereochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Meng [Yale Univ., New Haven, CT (United States); Schley, Nathan D [Yale Univ., New Haven, CT (United States); Crabtree, Robert H [Yale Univ., New Haven, CT (United States)


    A series of Cp*Ir complexes can catalyze C-H oxidation, with ceric ammonium nitrate as the terminal oxidant and water as the source of oxygen. Remarkably the hydroxylation of cis-decalin and 1,4-dimethylcyclohexane proceeds with retention of stereochemistry. With H2O18, cis-decalin oxidation gave 18O incorporation into the product cis-decalol.

  6. Structure and stereochemistry of electrochemically synthesized poly-(1-naphthylamine) from neutral acetonitrile solution




    Poly-(1-naphthylamine) films were synthesized potentiodinamically and potentiostatically from 1-naphthylamine in neutral acetonitrile medium using a platinum electrode. These polymer films were investigated by infrared spectroscopy. Contrary to earlier published results neglecting the stereochemistry of the poly-(1-naphthylamine), we predict on the basis of quantum stereochemical analysis of the possible structural subunits of the polymer, that the ordinary NC(4) coupled product is not predom...

  7. Assigning stereochemistry to single diastereoisomers by GIAO NMR calculation: the DP4 probability. (United States)

    Smith, Steven G; Goodman, Jonathan M


    GIAO NMR shift calculation has been applied to the challenging task of reliably assigning stereochemistry with quantifiable confidence when only one set of experimental data are available. We have compared several approaches for assigning a probability to each candidate structure and have tested the ability of these methods to distinguish up to 64 possible diastereoisomers of 117 different molecules, using NMR shifts obtained in rapid and computationally inexpensive single-point calculations on molecular mechanics geometries without time-consuming ab initio geometry optimization. We show that a probability analysis based on the errors in each (13)C or (1)H shift is significantly more successful at making correct assignments with high confidence than are probabilities based on the correlation coefficient and mean absolute error parameters. Our new probability measure, which we have termed DP4, complements the probabilities obtained from our previously developed CP3 parameter, which applies to the case of assigning a pair of diastereoisomers when one has both experimental data sets. We illustrate the application of DP4 to assigning the stereochemistry or structure of 21 natural products that were originally misassigned in the literature or that required extensive synthesis of diastereoisomers to establish their stereochemistry.

  8. Improved stability and performance from sigma-delta modulators using 1-bit vector quantization

    DEFF Research Database (Denmark)

    Risbo, Lars


    A novel class of sigma-delta modulators is presented. The usual scalar 1-b quantizer in a sigma-delta modulator is replaced by a 1-b vector quantizer with a N-dimensional input state-vector from the linear feedback filter. Generally, the vector quantizer changes the nonlinear dynamics...

  9. Temperature-Dependent Light-Stabilized States in Thin-Film PV Modules

    Energy Technology Data Exchange (ETDEWEB)

    Deceglie, Michael G.; Silverman, Timothy J.; Marion, Bill; Kurtz, Sarah R.


    Thin-film photovoltaic modules are known to exhibit light-induced transient behavior which interferes with accurate and repeatable measurements of power. Typically power measurements are made after a light exposure in order to target a 'light state' of the module that is representative of outdoor performance. Here we show that the concept of a unique light state is poorly defined for both CIGS and CdTe modules. Instead we find that their metastable state after a light exposure can depend on the temperature of the module during the exposure. We observe changes in power as large as 5.8% for a 20 degrees C difference in light exposure temperature. These results lead us to conclude that for applications in which reproducibility and repeatability are critical, module temperature should be tightly controlled during light exposure.

  10. Temperature-Dependent Light-Stabilized States in Thin-Film PV Modules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Deceglie, Michael G.; Silverman, Timothy J.; Marion, Bill; Kurtz, Sarah R.


    Thin-film photovoltaic modules are known to exhibit light-induced transient behavior which interferes with accurate and repeatable measurements of power. Typically power measurements are made after a light exposure in order to target a 'light state' of the module that is representative of outdoor performance. Here we show that the concept of a unique light state is poorly defined for both CIGS and CdTe modules. Instead we find that their metastable state after a light exposure can depend on the temperature of the module during the exposure. We observe changes in power as large as 5.8% for a 20 degrees C difference in light exposure temperature. These results lead us to conclude that for applications in which reproducibility and repeatability are critical, module temperature should be tightly controlled during light exposure.

  11. Dynamic head-neck stabilization and modulation with perturbation bandwidth investigated using a multisegment neuromuscular model

    NARCIS (Netherlands)

    Happee, R. (Riender); de Bruijn, E. (Edo); Forbes, P.A. (Patrick A.); F.C.T. van der Helm (Frans C.)


    textabstractThe human head-neck system requires continuous stabilization in the presence of gravity and trunk motion. We investigated contributions of the vestibulocollic reflex (VCR), the cervicocollic reflex (CCR), and neck muscle co-contraction to head-in-space and head-on-trunk stabilization,

  12. Dynamic head-neck stabilization and modulation with perturbation bandwidth investigated using a multisegment neuromuscular model

    NARCIS (Netherlands)

    Happee, R.; de Bruijn, E.; Forbes, P.A.; van der Helm, F.C.T.


    The human head-neck system requires continuous stabilization in the presence of gravity and trunk motion. We investigated contributions of the vestibulocollic reflex (VCR), the cervicocollic reflex (CCR), and neck muscle co-contraction to head-in-space and head-on-trunk stabilization, and

  13. Chiral Cyclobutane β-Amino Acid-Based Amphiphiles: Influence of Cis/Trans Stereochemistry on Solution Self-Aggregation and Recognition. (United States)

    Sorrenti, Alessandro; Illa, Ona; Pons, Ramon; Ortuño, Rosa M


    Novel diastereomeric anionic amphiphiles based on the rigid cyclobutane β-amino acid scaffold have been synthesized and deeply investigated with the aim of generating new functional supramolecular architectures on the basis of the rational design of original amphiphilic molecules and the control of their self-assembly. The main interest has been focused on the effect that cis/trans stereochemistry exerts on their molecular organization and recognition. In diluted solutions, the relative stereochemistry mainly influences the headgroup solvation and anionic-charge stabilization, i.e., better stabilized in the cis diastereoisomer due to intramolecular hydrogen-bonding and/or charge-dipole interactions. This provokes differences in their physicochemical behavior (pKa, cmc, conductivity) as well as in the structural parameters of the spherical micelles formed. Although both diastereoisomers form fibers that evolve with time from the spherical micelles, they display markedly different morphology and kinetics of formation. In the lyotropic liquid crystal domain, the greatest differences are observed at the highest concentrations and can be ascribed to different hydrogen-bonding and molecular packing imposed by the stereochemical constraints. Remarkably, the spherical micelles of the two anionic surfactants show dramatically diverse enantioselection ability for bilirubin enantiomers. In addition, both the surfactants form heteroaggregates with bilirubin at submicellar concentrations but with a different expression of supramolecular chirality. This points out that the unlike relative configuration of the two surfactants influences their chiral recognition ability as well as the fashion in which chirality is expressed at the supramolecular level by controlling the molecular organization in both micellar aggregates and surfactant/bilirubin heteroaggregates. All these differential features can be appropriate and useful for the design and development of new soft materials with

  14. Modulating toroidal flow stabilization of edge localized modes with plasma density

    CERN Document Server

    Cheng, Shikui; Banerjee, Debabrata


    Recent EAST experiments have demonstrated mitigation and suppression of edge localized modes (ELMs) with toroidal rotation flow in higher collisionality regime, suggesting potential roles of plasma density. In this work, the effects of plasma density on the toroidal flow stabilization of the high-$n$ edge localized modes have been extensively studied in linear calculations for a circular-shaped limiter H-mode tokamak, using the extended MHD code NIMROD. In the single MHD model, toroidal flow has a weak stabilizing effects on the high-$n$ modes. Such a stabilization, however, can be significantly enhanced with the increase in plasma density. Furthermore, our calculations show that the enhanced stabilization of high-$n$ modes from toroidal flow with higher edge plasma density persists in the 2-fluid MHD model. These findings may explain the ELM mitigation and suppression by toroidal rotation in higher collisionality regime due to the enhancement of plasma density obtained in recent EAST experiments.

  15. Creep in Photovoltaic Modules: Examining the Stability of Polymeric Materials and Components

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D. C.; Kempe, M. D.; Glick, S. H.; Kurtz, S. R.


    Interest in renewable energy has motivated the implementation of new polymeric materials in photovoltaic modules. Some of these are non-cross-linked thermoplastics, in which there is a potential for new behaviors to occur, including phase transformation and visco-elastic flow. Differential scanning calorimetry and rheometry data were obtained and then combined with existing site-specific time-temperature information in a theoretical analysis to estimate the displacement expected to occur during module service life. The analysis identified that, depending on the installation location, module configuration and/or mounting configuration, some of the thermoplastics are expected to undergo unacceptable physical displacement. While the examples here focus on encapsulation materials, the concerns apply equally to the frame, junction-box, and mounting-adhesive technologies.

  16. Computational validation of the importance of absolute stereochemistry in virtual screening. (United States)

    Brooks, Wesley H; Daniel, Kenyon G; Sung, Shen-Shu; Guida, Wayne C


    Consideration of stereochemistry early in the identification and optimization of lead compounds can improve the efficiency and efficacy of the drug discovery process and reduce the time spent on subsequent drug development. These improvements can result by focusing on specific enantiomers that have the desired potential therapeutic effect (eutomers), while removing from consideration enantiomers that may have no, or even undesirable, effects (distomers). A virtual screening campaign that correctly takes stereochemical information into account can, in theory, be utilized to provide information about the relative binding affinities of enantiomers. Thus, the proper enumeration of the relevant stereoisomers in general, and enantiomeric pairs in particular, of chiral compounds is crucial if one is to use virtual screening as an effective drug discovery tool. As is obvious, in cases where no stereochemical information is provided for chiral compounds in a 2D chemical database, then each possible stereoisomer should be generated for construction of the subsequent 3D database to be used for virtual screening. However, acute problems can arise in 3D database construction when relative stereochemistry is encoded in a 2D database for a chiral compound containing multiple stereogenic atoms but absolute stereochemistry is not implied. In this case, we report that generation of enantiomeric pairs is imperative in database development if one is to obtain accurate docking results. A study is described on the impact of the neglect of enantiomeric pairs on virtual screening using the human homolog of murine double minute 2 (MDM2) protein, the product of a proto-oncogene, as the target. Docking in MDM2 with GLIDE 4.0 was performed using the NCI Diversity Set 3D database and, for comparison, a set of enantiomers we created corresponding to mirror image structures of the single enantiomers of chiral compounds present in the NCI Diversity Set. Our results demonstrate that potential lead

  17. Sesquiterpene lactone stereochemistry influences herbivore resistance and plant fitness in the field. (United States)

    Ahern, Jeffrey R; Whitney, Kenneth D


    Stereochemical variation is widely known to influence the bioactivity of compounds in the context of pharmacology and pesticide science, but our understanding of its importance in mediating plant-herbivore interactions is limited, particularly in field settings. Similarly, sesquiterpene lactones are a broadly distributed class of putative defensive compounds, but little is known about their activities in the field. Natural variation in sesquiterpene lactones of the common cocklebur, Xanthium strumarium (Asteraceae), was used in conjunction with a series of common garden experiments to examine relationships between stereochemical variation, herbivore damage and plant fitness. The stereochemistry of sesquiterpene lactone ring junctions helped to explain variation in plant herbivore resistance. Plants producing cis-fused sesquiterpene lactones experienced significantly higher damage than plants producing trans-fused sesquiterpene lactones. Experiments manipulating herbivore damage above and below ambient levels found that herbivore damage was negatively correlated with plant fitness. This pattern translated into significant fitness differences between chemotypes under ambient levels of herbivore attack, but not when attack was experimentally reduced via pesticide. To our knowledge, this work represents only the second study to examine sesquiterpene lactones as defensive compounds in the field, the first to document herbivore-mediated natural selection on sesquiterpene lactone variation and the first to investigate the ecological significance of the stereochemistry of the lactone ring junction. The results indicate that subtle differences in stereochemistry may be a major determinant of the protective role of secondary metabolites and thus of plant fitness. As stereochemical variation is widespread in many groups of secondary metabolites, these findings suggest the possibility of dynamic evolutionary histories within the Asteraceae and other plant families showing

  18. Stabilization

    Directory of Open Access Journals (Sweden)

    Muhammad H. Al-Malack


    Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.

  19. Modulation and Stabilization of Silk Fibroin-Coated Oil-in-Water Emulsions

    Directory of Open Access Journals (Sweden)

    Zhong-Min Chen


    Full Text Available The purpose of this study is to prepare and characterize stable oil-in-water emulsions containing droplets coated with silk fibroin. Silk fibroin, a native edible fibrous protein originating from silkworm cocoons, was used to prepare 10 % (by mass corn oil-in-water emulsions at ambient temperature (pH=7.0, 10 mM phosphate buffer. Emulsions with relatively small mean particle diameter (d32=0.47 μm and extremely good creaming stability (>7 days could be produced at silk fibroin concentration of 1 % (by mass. The influence of pH (2–8, thermal processing (60–90 °C, 20 min, and concentration of salt (c(NaCl=0–250 mM on the properties and stability of the emulsions was analyzed using ζ-potential, particle size, and creaming stability measurements. The isoelectric point of droplets stabilized with silk fibroin was pH~4. The emulsions were stable to droplet flocculation and creaming at any pH except intermediate value (pH=4.0 when stored at room temperature, which was attributed to their relatively low ζ-potential. Their ζ-potential went from around 25 to –35 mV as the pH was increased from 2 to 8. The emulsions were also stable to thermal treatment (60 and 90 °C for 20 min, pH=3 and 7, with a slight decrease in the magnitude of ζ-potential at temperatures exceeding 60 °C. The emulsions were unstable to aggregation and creaming even at relatively low salt concentrations (c(NaCl=0–250 mM, pH=3 and 7 as a result of electrostatic screening effects. These results suggest that bulk oil stabilized with silk fibroin has improved physical stability and may provide a new way of creating functional oil products and delivery systems.

  20. Stability predictions for high-order ΣΔ modulators based on quasilinear modeling

    DEFF Research Database (Denmark)

    Risbo, Lars


    This paper introduces a novel interpretation of the instability mechanisms in high-order one-bit Sigma-Delta modulators. Furthermore, it is demonstrated how the maximum stable amplitude range can be predicted very well. The results are obtained using an extension of the well known quasilinear...

  1. Stability analysis and dynamic response of a DC-link module with a series voltage compensator

    DEFF Research Database (Denmark)

    Wang, Huai; Liu, Wenchao; Chung, Henry


    A DC-link module composed of a reduced value of DC-link capacitor and a series voltage compensator has been proposed. The voltage compensator processes the ripple voltage on the DC link and reactive power only, which can be implemented by low-voltage devices. The overall energy storage of the DC...

  2. Numerical Simulations, Mean Field Theory and Modulational Stability Analysis of Thermohaline Intrusions (United States)


    the temporal and spatial variability of the ocean circulation (Schmitt, 2003). This signifies that these thermohaline intrusions cannot be ignored...still calculating the net effects of double diffusion via crude parameterizations, the study showed that the thermohaline circulations in the model...SIMULATIONS, MEAN FIELD THEORY AND MODULATIONAL STABLITY ANALYSIS OF THERMOHALINE INTRUSIONS by Mark A. Hebert September 2011 Thesis Advisor

  3. Stability of bimanual coordination in Parkinson's disease and cognitive modulation of intention

    NARCIS (Netherlands)

    Geuze, RH


    The functional integrity of the bimanual neuro-motor system of Parkinson's disease (PD) subjects (stage II) compared to controls (2 X n = 16) was evaluated by measures of coordination stability of tapping in in-phase, anti-phase, and 90 degrees -phase. Recently, intentional influence was modeled as

  4. Modulations of NeuroD activity contribute to the differential effects of morphine and fentanyl on dendritic spine stability (United States)

    Hui, Zheng; Zeng, Yan; Chu, Ji; Kam, Angel YuetFang; Loh, Horace H.; Law, Ping-Yee


    The cellular level of neurogenic differentiation 1 (NeuroD) is modulated differentially by μ-opioid receptor agonists: fentanyl increases NeuroD level by reducing the amount of miR-190, an inhibitor of NeuroD expression, whereas morphine does not alter NeuroD level. In the current study, NeuroD activity was demonstrated to be also under agonist-dependent regulation. After three-day treatment, morphine and fentanyl decreased the activity of the Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα), which phosphorylates and activates NeuroD. Because NeuroD activity is determined by both the CaMKIIα activity and the cellular NeuroD level, the overall NeuroD activity was reduced by morphine, but maintained during fentanyl treatment. The differential effects of agonists on NeuroD activity were further confirmed by measuring the mRNA levels of four NeuroD downstream targets: doublecortin, Notch1, NeuroD4 and Roundabout 1. Decreased dendritic spine stability and μ-opioid receptor signaling capability were also observed when NeuroD activity was attenuated by miR-190 overexpression or treatment with KN93, a CaMKIIα inhibitor. The decrease could be rescued by NeuroD overexpression which restored NeuroD activity to the basal level. Furthermore, elevating NeuroD activity attenuated the morphine-induced decrease in dendritic spine stability. Therefore, by regulating NeuroD activity, μ-opioid receptor agonists modulate the stability of dendritic spines. PMID:20554861

  5. Modulation of toxin stability by 4-phenylbutyric acid and negatively charged phospholipids.

    Directory of Open Access Journals (Sweden)

    Supriyo Ray

    Full Text Available AB toxins such as ricin and cholera toxin (CT consist of an enzymatic A domain and a receptor-binding B domain. After endocytosis of the surface-bound toxin, both ricin and CT are transported by vesicle carriers to the endoplasmic reticulum (ER. The A subunit then dissociates from its holotoxin, unfolds, and crosses the ER membrane to reach its cytosolic target. Since protein unfolding at physiological temperature and neutral pH allows the dissociated A chain to attain a translocation-competent state for export to the cytosol, the underlying regulatory mechanisms of toxin unfolding are of paramount biological interest. Here we report a biophysical analysis of the effects of anionic phospholipid membranes and two chemical chaperones, 4-phenylbutyric acid (PBA and glycerol, on the thermal stabilities and the toxic potencies of ricin toxin A chain (RTA and CT A1 chain (CTA1. Phospholipid vesicles that mimic the ER membrane dramatically decreased the thermal stability of RTA but not CTA1. PBA and glycerol both inhibited the thermal disordering of RTA, but only glycerol could reverse the destabilizing effect of anionic phospholipids. In contrast, PBA was able to increase the thermal stability of CTA1 in the presence of anionic phospholipids. PBA inhibits cellular intoxication by CT but not ricin, which is explained by its ability to stabilize CTA1 and its inability to reverse the destabilizing effect of membranes on RTA. Our data highlight the toxin-specific intracellular events underlying ER-to-cytosol translocation of the toxin A chain and identify a potential means to supplement the long-term stabilization of toxin vaccines.

  6. Numerical Stability and Accuracy of Temporally Coupled Multi-Physics Modules in Wind-Turbine CAE Tools

    Energy Technology Data Exchange (ETDEWEB)

    Gasmi, A.; Sprague, M. A.; Jonkman, J. M.; Jones, W. B.


    In this paper we examine the stability and accuracy of numerical algorithms for coupling time-dependent multi-physics modules relevant to computer-aided engineering (CAE) of wind turbines. This work is motivated by an in-progress major revision of FAST, the National Renewable Energy Laboratory's (NREL's) premier aero-elastic CAE simulation tool. We employ two simple examples as test systems, while algorithm descriptions are kept general. Coupled-system governing equations are framed in monolithic and partitioned representations as differential-algebraic equations. Explicit and implicit loose partition coupling is examined. In explicit coupling, partitions are advanced in time from known information. In implicit coupling, there is dependence on other-partition data at the next time step; coupling is accomplished through a predictor-corrector (PC) approach. Numerical time integration of coupled ordinary-differential equations (ODEs) is accomplished with one of three, fourth-order fixed-time-increment methods: Runge-Kutta (RK), Adams-Bashforth (AB), and Adams-Bashforth-Moulton (ABM). Through numerical experiments it is shown that explicit coupling can be dramatically less stable and less accurate than simulations performed with the monolithic system. However, PC implicit coupling restored stability and fourth-order accuracy for ABM; only second-order accuracy was achieved with RK integration. For systems without constraints, explicit time integration with AB and explicit loose coupling exhibited desired accuracy and stability.

  7. Work function modulation and thermal stability of reduced graphene oxide gate electrodes in MOS devices. (United States)

    Misra, Abhishek; Kalita, Hemen; Kottantharayil, Anil


    Work function (WF) tuning of the contact electrodes is a key requirement in several device technologies, including organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), and complementary metal oxide semiconductor (CMOS) transistors. Here, we demonstrate that the WF of the gate electrode in an MOS structure can be modulated from 4.35 eV (n-type metal) to 5.28 eV (p-type metal) by sandwiching different thicknesses of reduced graphene oxide (rGO) layers between top contact metals and gate dielectric SiO2. The WF of the gate electrode shows strong dependence on the rGO thickness and is seen to be nearly independent of the contact metals used. The observed WF modulation is attributed to the different amounts of oxygen concentrations in different thicknesses of rGO layers. Importantly, this oxygen concentration can also be varied by the reduction extent of the graphene oxide as experimentally demonstrated. The results are verified by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses. The obtained WF values are thermally stable up to 800 °C. At further high temperatures, diffusion of metal through the rGO sheets is the main cause for WF instability, as confirmed by cross-sectional high-resolution transmission electron microscopy analysis. These findings are not limited to MOS devices, and the WF modulation technique has the potential for applications in other technologies such as OLEDs and OPVs involving graphene as conducting electrodes.

  8. Modified penicillin molecule with carbapenem-like stereochemistry specifically inhibits Class C β-lactamases. (United States)

    Pan, Xuehua; He, Yunjiao; Chen, Tianfeng; Chan, Kin-Fai; Zhao, Yanxiang


    Bacterial β-lactamases readily inactivate most penicillins and cephalosporins by hydrolyzing and "opening" their signature β-lactam ring. In contrast, carbapenems resist hydrolysis by many serine-based Class A, C and D β-lactamases due to their unique stereochemical features. To improve the resistance profile of penicillins, we synthesized a modified penicillin molecule MPC-1 by "grafting" carbapenem-like stereochemistry onto the penicillin core. Chemical modifications include the trans conformation of hydrogen atoms at C5 and C6 instead of cis, and a 6-α hydroxyethyl moiety to replace the original 6-β aminoacyl group. MPC-1 selectively inhibits Class C β-lactamase such as P99 by forming a non-hydrolyzable acyl adduct and its inhibitory potency is ∼2-5 times higher than that for clinically used β-lactamase inhibitors clavulanate and sulbactam. Crystal structure of MPC-1 forming acyl adduct with P99 reveals a novel binding mode for MPC-1 that resembles carbapenem bound in the active site of Class A β-lactamase. Furthermore, in this novel binding mode, the carboxyl group of MPC-1 blocks the deacylation reaction by occluding the critical catalytic water molecule and renders the acyl adduct non-hydrolyzable. Our results suggest that, by incorporating carbapenem-like stereochemistry, the current collection of over 100 penicillins and cephalosporins can be modified into candidate compounds for development of novel β-lactamase inhibitors. Copyright © 2017 American Society for Microbiology.

  9. Heat shock modulates the subcellular localization, stability, and activity of HIPK2

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Mamta; Bhadauriya, Pratibha; Ganesh, Subramaniam, E-mail:


    The homeodomain-interacting protein kinase-2 (HIPK2) is a highly conserved serine/threonine kinase and is involved in transcriptional regulation. HIPK2 is a highly unstable protein, and is kept at a low level under normal physiological conditions. However, exposure of cells to physiological stress – such as hypoxia, oxidative stress, or UV damage – is known to stabilize HIPK2, leading to the HIPK2-dependent activation of p53 and the cell death pathway. Therefore HIPK2 is also known as a stress kinase and as a stress-activated pro-apoptotic factor. We demonstrate here that exposure of cells to heat shock results in the stabilization of HIPK2 and the stabilization is mediated via K63-linked ubiquitination. Intriguingly, a sub-lethal heat shock (42 °C, 1 h) results in the cytoplasmic localization of HIPK2, while a lethal heat shock (45 °C, 1 h) results in its nuclear localization. Cells exposed to the lethal heat shock showed significantly higher levels of the p53 activity than those exposed to the sub-lethal thermal stress, suggesting that both the level and the nuclear localization are essential for the pro-apoptotic activity of HIPK2 and that the lethal heat shock could retain the HIPK2 in the nucleus to promote the cell death. Taken together our study underscores the importance of HIPK2 in stress mediated cell death, and that the HIPK2 is a generic stress kinase that gets activated by diverse set of physiological stressors.

  10. Inversion of the stereochemistry around the sulfur atom of the axial methionine side chain through alteration of amino acid side chain packing in Hydrogenobacter thermophilus cytochrome C552 and its functional consequences. (United States)

    Tai, Hulin; Tonegawa, Ken; Shibata, Tomokazu; Hemmi, Hikaru; Kobayashi, Nagao; Yamamoto, Yasuhiko


    In cytochrome c, the coordination of the axial Met Sδ atom to the heme Fe atom occurs in one of two distinctly different stereochemical manners, i.e., R and S configurations, depending upon which of the two lone pairs of the Sδ atom is involved in the bond; hence, the Fe-coordinated Sδ atom becomes a chiral center. In this study, we demonstrated that an alteration of amino acid side chain packing induced by the mutation of a single amino acid residue, i.e., the A73V mutation, in Hydrogenobacter thermophilus cytochrome c552 (HT) forces the inversion of the stereochemistry around the Sδ atom from the R configuration [Travaglini-Allocatelli, C., et al. (2005) J. Biol. Chem. 280, 25729-25734] to the S configuration. Functional comparison between the wild-type HT and the A73V mutant possessing the R and S configurations as to the stereochemistry around the Sδ atom, respectively, demonstrated that the redox potential (Em) of the mutant at pH 6.00 and 25 °C exhibited a positive shift of ∼20 mV relative to that of the wild-type HT, i.e., 245 mV, in an entropic manner. Because these two proteins have similar enthalpically stabilizing interactions, the difference in the entropic contribution to the Em value between them is likely to be due to the effect of the conformational alteration of the axial Met side chain associated with the inversion of the stereochemistry around the Sδ atom due to the effect of mutation on the internal mobility of the loop bearing the axial Met. Thus, the present study demonstrated that the internal mobility of the loop bearing the axial Met, relevant to entropic control of the redox function of the protein, is affected quite sensitively by the contextual stereochemical packing of amino acid side chains in the proximity of the axial Met.

  11. O-GlcNAcylation modulates Bmi-1 protein stability and potential oncogenic function in prostate cancer. (United States)

    Li, Y; Wang, L; Liu, J; Zhang, P; An, M; Han, C; Li, Y; Guan, X; Zhang, K


    The Polycomb group transcriptional repressor Bmi-1 often overexpressed and participated in stem cells self-renewal and tumorigenesis initiating of prostate cancer. In this progression, Bmi-1 protein was regulated by transcription and post-translational modifications (PTMs). Nobly, the underlying PTMs regulation of Bmi-1 is poorly known. Here we use co-immunoprecipitation show that in C4-2 cell line, Bmi-1 directly interacted with OGT which is the only known enzyme catalyzed the O-GlcNAcylation in human. Furthermore, we identified that Ser255 is the site for Bmi-1 O-GlcNAcylation, and O-GlcNAcylation promoted Bmi-1 protein stability and its oncogenic activity. Finally, microarray analysis has characterized potential oncogenes associated pathway subject to repression via the OGT-Bmi-1 axis. Taken together, these results indicate that OGT-mediated O-GlcNAcylation at Ser255 stabilizes Bmi-1 and hence inhibits the TP53, PTEN and CDKN1A/CDKN2A pathway. The study not only uncovers a novel functional PTMs of Bmi-1 but also reveals a unique oncogenic role of O-GlcNAcylation in prostate cancer.

  12. Stability of skeletal changes induced by growth modulation procedures in the treatment of skeletal Class II malocclusion

    Directory of Open Access Journals (Sweden)

    Prashantha Govinakovi Shivamurthy


    Full Text Available Objective: Objective of this study, based on an evaluation of lateral cephalograms, was to evaluate the degree of skeletal changes produced by the various growth modulative procedures in the treatment of skeletal Class II malocclusion and to characterize the stability of these changes in the years after treatment. Materials and Methods: Total of 40 patients with Class II malocclusion was divided into three groups according to appliance used, i.e. removable or fixed functional appliances (n = 10, combination of functional appliance with headgear (n = 10, and only headgear (n = 10. In addition, almost a matched control group (n = 10 also characterized by skeletal Class II pattern and were under observation, for more than 2 years was also selected. Lateral cephalograms of each patient were taken at the start of treatment (T1, at its completion (T2, and long-term posttreatment (T3. Results: This study showed significant improvement in maxillomandibular relationship in treated group compared to control group, and the changes remained stable in posttreatment phase. Restriction of maxillary growth was evident in headgear and combination groups whereas significant forward movement of the mandible was seen in functional group. Conclusion: Analysis of lateral cephalograms indicates that growth modulation therapy in angle Class II malocclusion brings about desired skeletal changes which remain relatively stable over a long-term period.

  13. Terminal Interface Conformations Modulate Dimer Stability Prior to Amino Terminal Autoprocessing of HIV-1 Protease

    Energy Technology Data Exchange (ETDEWEB)

    Agniswamy, Johnson; Sayer, Jane M.; Weber, Irene T.; Louis, John M. (GSU); (NIH)


    The HIV-1 protease (PR) mediates its own release (autoprocessing) from the polyprotein precursor, Gag-Pol, flanked by the transframe region (TFR) and reverse transcriptase at its N- and C-termini, respectively. Autoprocessing at the N-terminus of PR mediates stable dimer formation essential for catalytic activity, leading to the formation of infectious virus. An antiparallel {beta}-sheet interface formed by the four N- and C-terminal residues of each subunit is important for dimer stability. Here, we present the first high-resolution crystal structures of model protease precursor-clinical inhibitor (PI darunavir or saquinavir) complexes, revealing varying conformations of the N-terminal flanking (S{sup -4}FNF{sup -1}) and interface residues (P{sup 1}QIT{sup 4}). A 180{sup o} rotation of the T{sup 4}-L{sup 5} peptide bond is accompanied by a new Q{sup 2}-L{sup 5} hydrogen bond and complete disengagement of PQIT from the {beta}-sheet dimer interface, which may be a feature for intramolecular autoprocessing. This result is consistent with drastically lower thermal stability by 14-20 C of PI complexes of precursors and the mature PR lacking its PQIT residues (by 18.3 C). Similar to the TFR-PR precursor, this deletion also results in a darunavir dissociation constant (2 x 10{sup 4})-fold higher and a markedly increased dimer dissociation constant relative to the mature PR. The terminal {beta}-sheet perturbations of the dimeric structure likely account for the drastically poorer inhibition of autoprocessing of TFR-PR relative to the mature PR, even though significant differences in active site-PI interactions in these structures were not observed. The novel conformations of the dimer interface may be exploited to target selectively the protease precursor prior to its N-terminal cleavage.

  14. The modulating role of group stability on fitness effects of group size is different in females and males of a communally rearing rodent. (United States)

    Ebensperger, Luis A; Correa, Loreto A; León, Cecilia; Ramírez-Estrada, Juan; Abades, Sebastian; Villegas, Álvaro; Hayes, Loren D


    Group size may influence fitness benefits and costs that emerge from cooperative and competitive interactions in social species. However, evidence from plural breeding mammals indicates that group size is insufficient to explain variation in direct fitness, implying other attributes of social groups were overlooked. We studied the natural population of a social rodent during 5 years to test the hypothesis that social stability - in terms of group composition - modulates the effects of increasing number of breeding females (a proxy of communal rearing) and males on the number of offspring weaned (sired) and on the number of offspring weaned (sired) surviving to breeding age (two proxies of direct fitness). We quantified the effects of social stability (measured as changes in female or male group members between mating and the onset of lactation) on these fitness measures. We used live trapping, telemetry and DNA markers to determine social and fitness measures. Social stability in degus was variable in terms of the number of changes in group composition across groups. Low stability was mostly due to mortality and emigration of group members. Results supported a modulating role of social stability on the relationship between group size and the number of offspring weaned (sired). Stability in female and male group composition were both modulators of fitness to females and males. The modulatory role of stability was sex specific, where high social stability was often fitness beneficial to the females. Instead, low social stability was fitness enhancing to the males. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  15. Structure and stereochemistry of electrochemically synthesized poly-(1-naphthylamine from neutral acetonitrile solution

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    Full Text Available Poly-(1-naphthylamine films were synthesized potentiodinamically and potentiostatically from 1-naphthylamine in neutral acetonitrile medium using a platinum electrode. These polymer films were investigated by infrared spectroscopy. Contrary to earlier published results neglecting the stereochemistry of the poly-(1-naphthylamine, we predict on the basis of quantum stereochemical analysis of the possible structural subunits of the polymer, that the ordinary N–C(4 coupled product is not predominant in the polymer because it is far removed from the expected planarity. Based on the results of IR investigations and semiempirical quantum chemical calculations, it is propose that the polymer products are formed via mixed N–C(4, N-C(5 and N–C(7 coupling routes. The heats of formation of the oxidized 1-naphthylamine dimers and hexamers were calculated.

  16. Stereochemistry of host plant monoterpenes as mate location cues for the gall wasp Antistrophus rufus. (United States)

    Tooker, John F; Hanks, Lawrence M


    In spring, adult males of the gall wasp Antistrophus rufus L. emerge from inconspicuous galls in stems of their host plant Silphium laciniatum L. and search for sites on stems where females will later emerge. The behavior of males suggests that they use olfaction rather than visual or tactile cues in searching for mates. In an earlier publication, we reported that galls of A. rufus were associated with changes in enantiomeric ratios of alpha- and beta-pinene emitted by plant stems, and hypothesized that monoterpene stereochemistry served as a mate location cue for adult males. Here, we support this hypothesis with bioassays that demonstrate that males can discriminate between galled and ungalled stems, as well as between blends of synthetic monoterpenes with ratios of enantiomers representative of galled and ungalled stems.

  17. Stability of behavioral estimates of activity-dependent modulation of pain

    Directory of Open Access Journals (Sweden)

    Alappattu MJ


    Full Text Available Meryl J Alappattu1, Mark D Bishop1, Joel E Bialosky1, Steven Z George1,2, Michael E Robinson2,31Department of Physical Therapy, University of Florida, Gainesville, FL, USA; 2Center for Pain Research and Behavioral Health, University of Florida, Gainesville, FL, USA; 3Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USAAbstract: Temporal sensory summation of pain (TSSP is a proxy measure of windup in humans and results in increased ratings of pain caused by a repetitive, low-frequency noxious stimulus. Aftersensations (ASs are pain sensations that remain after TSSP has been induced. We examined the within-session and across-session variability in TSSP and AS estimation in healthy participants and in participants with exercise-induced muscle pain in order to determine whether the presence of pain affected the stability of TSSP and ASs. TSSP was estimated by application of 10 repetitive, low-frequency (<0.33 Hz thermal pulses and measured by the simple slope of pain ratings between the first and fifth pulses. ASs were measured by the presence of any remaining pain sensations up to 1 minute after TSSP was induced. TSSP estimation remained moderately stable in pain-free participants and in participants with pain within a single testing session but demonstrated low stability across sessions in pain-free participants. AS estimation was stable for all groups. Estimation of TSSP and ASs using these protocols appears to be a reliable single-session outcome measure in studies of interventions for acute muscle pain and in experimental studies with healthy participants. This article evaluates the reliability of a commonly used method of estimating TSSP and ASs in both healthy participants and in a clinically relevant model of acute pain. These protocols have the potential to be used as single-session outcome measures for interventional studies and in experimental studies.Keywords: temporal sensory summation of pain

  18. Frequency Modulation and Spatiotemporal Stability of the sCPG in Preterm Infants with RDS

    Directory of Open Access Journals (Sweden)

    Steven M. Barlow


    Full Text Available The nonnutritive suck (NNS is an observable and accessible motor behavior which is often used to make inference about brain development and pre-feeding skill in preterm and term infants. The purpose of this study was to model NNS burst compression pressure dynamics in the frequency and time domain among two groups of preterm infants, including those with respiratory distress syndrome (RDS, N=15 and 17 healthy controls. Digitized samples of NNS compression pressure waveforms recorded at a 1-week interval were collected 15 minutes prior to a scheduled feed. Regression analysis and ANOVA revealed that healthy preterm infants produced longer NNS bursts and the mean burst initiation cycle frequencies were higher when compared to the RDS group. Moreover, the initial 5 cycles of the NNS burst manifest a frequency modulated (FM segment which is a significant feature of the suck central pattern generator (sCPG, and differentially expressed in healthy and RDS infants. The NNS burst structure revealed significantly lower spatiotemporal index values for control versus RDS preterm infants during FM, and provides additional information on the microstructure of the sCPG which may be used to gauge the developmental status and progression of oromotor control systems among these fragile infants.

  19. SUMOylation of AhR modulates its activity and stability through inhibiting its ubiquitination. (United States)

    Xing, Xinrong; Bi, Hailian; Chang, Alan K; Zang, Ming-Xi; Wang, Miao; Ao, Xiang; Li, Shen; Pan, Hongming; Guo, Qianping; Wu, Huijian


    Aryl hydrocarbon receptor (AhR) is a transcription factor that belongs to the basic helix-loop-helix (bHLH) Per-Arnt-Sim homology domain (PAS) family. AhR can be activated by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (2, 3, 7, 8-TCDD) and once activated, it promotes the abnormal expression of cytochrome P450, leading to several diseases, including cancer. In this study, we showed that AhR is subjected to post-translational modification by SUMOylation and this modification could be reversed by SENP1. Two SUMOylation sites were identified, one in the bHLH domain (K63) and the other in the TAD domain (K510) of AhR. Substitution of either K63 or K510 with arginine resulted in reduced SUMOylation for AhR. Treatment of MCF-7 cells with TCDD led to a reduced level of SUMOylated AhR in a time-dependent manner, and this occurred mainly in the nucleus. SUMOylation of AhR enhanced its stability through inhibiting its ubiquitination. Moreover, SUMOylation also repressed the transactivation activity of AhR and this could be reversed by TCDD. These results suggested that SUMOylation of AhR might play an important role in the regulation of its function, and TCDD may activate the transcriptional activity of AhR through downregulating its SUMOylation. Copyright © 2012 Wiley Periodicals, Inc.

  20. Thermal Stability of siRNA Modulates Aptamer- conjugated siRNA Inhibition

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    Alexey Berezhnoy


    Full Text Available Oligonucleotide aptamer-mediated in vivo cell targeting of small interfering RNAs (siRNAs is emerging as a useful approach to enhance the efficacy and reduce the adverse effects resulting from siRNA-mediated genetic interference. A current main impediment in aptamer-mediated siRNA targeting is that the activity of the siRNA is often compromised when conjugated to an aptamer, often requiring labor intensive and time consuming design and testing of multiple configurations to identify a conjugate in which the siRNA activity has not been significantly reduced. Here, we show that the thermal stability of the siRNA is an important parameter of siRNA activity in its conjugated form, and that siRNAs with lower melting temperature (Tm are not or are minimally affected when conjugated to the 3′ end of 2′F-pyrimidine-modified aptamers. In addition, the configuration of the aptamer-siRNA conjugate retains activity comparable with the free siRNA duplex when the passenger strand is co-transcribed with the aptamer and 3′ overhangs on the passenger strand are removed. The approach described in this paper significantly reduces the time and effort necessary to screening siRNA sequences that retain biological activity upon aptamer conjugation, facilitating the process of identifying candidate aptamer-siRNA conjugates suitable for in vivo testing.

  1. Pilot Dietary Intervention with Heat-Stabilized Rice Bran Modulates Stool Microbiota and Metabolites in Healthy Adults

    Directory of Open Access Journals (Sweden)

    Amy M. Sheflin


    Full Text Available Heat-stabilized rice bran (SRB has been shown to regulate blood lipids and glucose, modulate gut mucosal immunity and inhibit colorectal cancer in animal and human studies. However, SRB’s effects on gut microbial composition and metabolism and the resulting implications for health remain largely unknown. A pilot, randomized-controlled trial was developed to investigate the effects of eating 30 g/day SRB on the stool microbiome and metabolome. Seven healthy participants consumed a study meal and snack daily for 28 days. The microbiome and metabolome were characterized using 454 pyrosequencing and gas chromatography-mass spectrometry (GC-MS at baseline, two and four weeks post-intervention. Increases in eight operational taxonomic units (OTUs, including three from Bifidobacterium and Ruminococcus genera, were observed after two and four weeks of SRB consumption (p < 0.01. Branched chain fatty acids, secondary bile acids and eleven other putative microbial metabolites were significantly elevated in the SRB group after four weeks. The largest metabolite change was a rice bran component, indole-2-carboxylic acid, which showed a mean 12% increase with SRB consumption. These data support the feasibility of dietary SRB intervention in adults and support that SRB consumption can affect gut microbial metabolism. These findings warrant future investigations of larger cohorts evaluating SRB’s effects on intestinal health.

  2. O-GlcNAc Transferase/Host Cell Factor C1 Complex Regulates Gluconeogenesis by Modulating PGC-1α Stability (United States)

    Ruan, Hai-Bin; Han, Xuemei; Li, Min-Dian; Singh, Jay Prakash; Qian, Kevin; Azarhoush, Sascha; Zhao, Lin; Bennett, Anton M.; Samuel, Varman T.; Wu, Jing; Yates, John R.; Yang, Xiaoyong


    SUMMARY A major cause of hyperglycemia in diabetic patients is inappropriate hepatic gluconeogenesis. PGC-1α is a master regulator of gluconeogenesis, and its activity is controlled by various post-translational modifications. A small portion of glucose metabolizes through the hexosamine biosynthetic pathway, which leads to O-linked β-N-acetylglucosamine (O-GlcNAc) modification of cytoplasmic and nuclear proteins. Using a proteomic approach, we identified a broad variety of proteins associated with O-GlcNAc transferase (OGT), among which host cell factor C1 (HCF-1) is highly abundant. HCF-1 recruits OGT to O-GlcNAcylate PGC-1α and O-GlcNAcylation facilitates the binding of the deubiquitinase BAP1, thus protecting PGC-1α from degradation and promoting gluconeogenesis. Glucose availability modulates gluconeogenesis through the regulation of PGC-1α O-GlcNAcylation and stability by the OGT/HCF1 complex. Hepatic knockdown of OGT and HCF-1 improves glucose homeostasis in diabetic mice. These findings define the OGT/HCF-1 complex as a glucose sensor and key regulator of gluconeogenesis, shedding light on new strategies for treating diabetes. PMID:22883232

  3. Absolute stereochemistry of fungal beauveriolide III and ACAT inhibitory activity of four stereoisomers. (United States)

    Ohshiro, Taichi; Namatame, Ichiji; Nagai, Kenichiro; Sekiguchi, Takafumi; Doi, Takayuki; Takahashi, Takashi; Akasaka, Kazuaki; Rudel, Lawrence L; Tomoda, Hiroshi; Omura, Satoshi


    Fungal beauveriolide III (BeauIII, 1b), a cyclodepsipeptide inhibiting acyl-CoA:cholesterol acyltransferase (ACAT) and showing antiatherogenic activity in mouse models, consists of L-Phe, L-Ala, D-allo-Ile, and 3-hydroxy-4-methyloctanoic acid (HMA) moieties, but the stereochemistry of the HMA part has not until now been fully defined. To determine it, four HMA stereoisomers were synthesized and labeled with (S)-(+)-2-(anthracene-2,3-dicarboximido)-1-propyl trifluoromethane sulfonate (AP-OTf), a chiral fluorescent reagent. The derivatives were separated by HPLC and compared with the natural HMA derivative, which was thereby identified as (3S,4S)HMA in BeauIII. Furthermore, the four beauveriolide III isomers ((3S,4S)BeauIII (23a), (3R,4R)BeauIII (23b), (3R,4S)BeauIII (23c), and (3S,4R)BeauIII (23d)) were synthesized, and it was shown that all the spectral data for 23a were identical with those for natural 1b. Isomers 23a and 23d showed potent inhibitory activity of lipid droplet accumulation in macrophages, while the other two isomers caused weak inhibition. Thus, the 3S configuration of BeauIII is important for this activity. Furthermore, 23a and 23d showed rather specific inhibition against the ACAT1 isozyme.

  4. Methods for the comprehensive structural elucidation of constitution and stereochemistry of lipopeptides. (United States)

    Gerhardt, Heike; Sievers-Engler, Adrian; Jahanshah, Ghazaleh; Pataj, Zoltán; Ianni, Federica; Gross, Harald; Lindner, Wolfgang; Lämmerhofer, Michael


    A panel of methods of general suitability for complete structural elucidation of the stereochemistry of cyclopeptides, depsipeptides and lipopeptides is presented and described in detail. The suitability of the proposed methods was exemplified on the lipopeptide poaeamide from Pseudomonas poae. Amino acid configurations have been assigned by direct LC enantiomer separation with Chiralpak ZWIX(+) and were confirmed by GC enantiomer separation on Chirasil L-Val. 3-Hydroxydecanoic acid absolute configuration was analyzed on Chiralpak ZWIX(+) and confirmed by injection on ZWIX(-) which showed opposite elution order. Plenty of d-amino acids have been found in this lipopeptide. It contained in total 5 Leu residues of which one had d-configuration. The position of the d-Leu in the peptide sequence was determined by pepsin and chemical digestions in combination with isolation of diagnostic peptide-fragments and subsequent identification of absolute configurations of the Leu residues. This allowed pinpointing the position of the d-amino acid. The complementarity of the peptide retention profiles on Chiralpak ZWIX column as compared to both RPLC and HILIC suggests its great utility as an alternative peptide separation tool. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. The ubiquitin-conjugating enzyme UBE2O modulates c-Maf stability and induces myeloma cell apoptosis

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    Yujia Xu


    Full Text Available Abstract Background UBE2O is proposed as a ubiquitin-conjugating enzyme, but its function was largely unknown. Methods Mass spectrometry was applied to identify c-Maf ubiquitination-associated proteins. Immunoprecipitation was applied for c-Maf and UBE2O interaction. Immunoblotting was used for Maf protein stability. Luciferase assay was used for c-Maf transcriptional activity. Lentiviral infections were applied for UBE2O function in multiple myeloma (MM cells. Flow cytometry and nude mice xenografts were applied for MM cell apoptosis and tumor growth assay, respectively. Results UBE2O was found to interact with c-Maf, a critical transcription factor in MM, by the affinity purification/tandem mass spectrometry assay and co-immunoprecipitation assays. Subsequent studies showed that UBE2O mediated c-Maf polyubiquitination and degradation. Moreover, UBE2O downregulated the transcriptional activity of c-Maf and the expression of cyclin D2, a typical gene modulated by c-Maf. DNA microarray revealed that UBE2O was expressed in normal bone marrow cells but downregulated in MGUS, smoldering MM and MM cells, which was confirmed by RT-PCR in primary MM cells, suggesting its potential role in myeloma pathophysiology. When UBE2O was restored, c-Maf protein in MM cells was significantly decreased and MM cells underwent apoptosis. Furthermore, the human MM xenograft in nude mice showed that re-expression of UBE2O delayed the growth of myeloma xenografts in nude mice in association with c-Maf downregulation and activation of the apoptotic pathway. Conclusions UBE2O mediates c-Maf polyubiquitination and degradation, induces MM cell apoptosis, and suppresses myeloma tumor growth, which provides a novel insight in understanding myelomagenesis and UBE2O biology.

  6. Modulating weak interactions for molecular recognition: a dynamic combinatorial analysis for assessing the contribution of electrostatics to the stability of CH-π bonds in water. (United States)

    Jiménez-Moreno, Ester; Gómez, Ana M; Bastida, Agatha; Corzana, Francisco; Jiménez-Oses, Gonzalo; Jiménez-Barbero, Jesús; Asensio, Juan Luis


    Electrostatic and charge-transfer contributions to CH-π complexes can be modulated by attaching electron-withdrawing substituents to the carbon atom. While clearly stabilizing in the gas phase, the outcome of this chemical modification in water is more difficult to predict. Herein we provide a definitive and quantitative answer to this question employing a simple strategy based on dynamic combinatorial chemistry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Biochemical aromatization of 2-methyleneandrostenedione: stereochemistry of hydrogen removal at the C-1 position. (United States)

    Numazawa, Mitsuteru; Handa, Wakako; Matsuzaki, Hisao


    To explore a stereochemistry of hydrogen removal at C-1 of the powerful aromatase inhibitor 2-methyleneandrostenedione (1), of which the A-ring conformation is markedly different from that of the natural substrate androstenedione (AD), in the course of the aromatase-catalyzed A-ring aromatization producing 2-methylestrone (2), we synthesized [1alpha-2H]labeled steroid 1 and its [1beta-2H]stereoisomer, and the metabolic fate of the C-1 deuterium in aromatization was analyzed by gas chromatography-mass spectrometry (GC-MS) in each. Parallel experiments with the natural substrates [1alpha-2H] and [1beta-2H]ADs were also carried out. The GC-MS analysis indicated that 2-methyl estrogen 2 produced from [1alpha-2H]labeled substrate 1 retained completely the 1alpha-deuterium (1beta-H elimination), while product 2 obtained from [1beta-2H]isomer 1 lost completely the 1beta-deuterium. Stereospecific 1beta-hydrogen elimination was also observed in the parallel experiments with the labeled ADs as established previously. The results indicate that biochemical aromatization of the 2-methylene steroid 1 proceeds through the 1beta-hydrogen removal concomitant with cleavage of the C(10)-C(19) bond, yielding 1(10),4-dienone 9, in a similar manner to that involved in AD aromatization. This would give additional evidence for the stereomechanisms for the last step of aromatization of AD, requiring the stereospecific 1beta-hydrogen abstraction and cleavage of the C(10)-C(19) bond, and for the enolization of a carbonyl group at C-3 in the A-ring aromatization.

  8. Nature of low dimensional structural modulations and relative phase stability in RexMo(W)1-xS2 transition metal dichalcogenide alloys

    KAUST Repository

    Sahu, R.


    We report on the various types of Peierls like two dimensional structural modulations and relative phase stability of 2H and 1T poly-types in the RexMo1-xS2 and RexW1-xS2 alloy system. Theoretical calculation predicts a polytype phase transition cross over at ∼50 at. % of Mo and W in ReS2 in both monolayer and bulk form, respectively. Experimentally, two different types of structural modulations at 50% and a modulation corresponding to trimerization at 75% alloy composition are observed for RexMo1-xS2 and only one type of modulation is observed at the 50% RexW1-xS2 alloy system. The 50% alloy system is found to be a suitable monolithic candidate for metal semiconductor transition with minute external perturbation. ReS2 is known to be in the 2D Peierls distorted 1Td structure and forms a chain like superstructure. Incorporation of Mo and W atoms into the ReS2 lattice modifies the metal-metal hybridization between the cations and influences the structural modulation and electronic properties of the system. The results offer yet another effective way to tune the electronic structure and poly-type phases of this class of materials other than intercalation, strain, and vertical stacking arrangement.

  9. Nondestructive evaluation of mechanically stabilized earth walls with frequency-modulated continuous wave (FM-CW) radar. (United States)


    Effective techniques for a nondestructive evaluation of mechanically stabilized earth (MSE) walls during normal operation : or immediately after an earthquake event are yet to be developed. MSE walls often have a rough surface finishing for the : pur...

  10. Vacuum stability testing of Apollo 15 Scientific Instrument Module (SIM) non-metallic materials and reversion of silicone rubber in a motor switch (United States)

    Clancy, H. M.


    Vacuum stability screening tests were performed on the Apollo 15 Scientific Instrument Module (SIM) bay nonmetallic materials in accordance with the NASA document SP-R-0022. The testing was necessary to support the evaluation to determine the effect material outgassing contamination would have on the SIM bay optical lenses and sensing devices. The Apollo 15 SIM experiments were highly successful, therefore, it is assumed that contamination due to the outgassing of nonmetallic materials did not affect equipment operation. A related problem, the reversion of a silicone rubber grommet which affected an electrical motor switch operation is also reported.

  11. Analysis of stereochemistry and biosynthesis of epicatechin in tea plants by chiral phase high performance liquid chromatography. (United States)

    Qian, Yumei; Zhao, Xianqian; Zhao, Lei; Cui, Lilan; Liu, Li; Jiang, Xiaolan; Liu, Yajun; Gao, Liping; Xia, Tao


    Tea (Camellia sinensis) is rich in flavan-3-ols (catechins), especially epicatechin (EC), which is the predominant extension unit of polymeric proanthocyanidins (PAs). However, studies assessing EC's stereochemistry are scarce. Here, a high performance liquid chromatography column using amylose tris-(3, 5-dimethylphenylcarbamate) immobilized on silica-gel as chiral stationary phases (CSPs) was applied to explore its stereochemistry and biosynthetic pathway in tea plants. The results revealed (-)-epicatechin [(-)-EC] was the predominant di-hyroxy-non-galloylated-catechins, while (+)-epicatechin [(+)-EC] was not detected. Interestingly, (-)-EC was the only product obtained from cyanidin using the partially purified native C. sinensis anthocyanidin reductase (CsANR) in the presence of reduction nicotinamide adenine dinucleotide phosphate (NADPH); meanwhile, (+)-EC was the main product using recombinant CsANR in the same conditions. In addition, (-)-EC could be obtained from (+)-catechin [(+)-C] using recombinant CsANR, which displayed C3-epimerase activity in the presence of oxidation nicotinamide adenine dinucleotide phosphate (NADP(+)). But the partially purified native CsANR did not possess this function. Finally, (-)-EC could result from the de-gallate acid reaction of epicatechin gallate (ECG) catalyzed by a novel partially purified native galloylated catechins hydrolase (GCH) from tea leaves. In summary, (-)-EC is likely the product of native protein from the tea plants, and (+)-EC is only produced in a reaction catalyzed by recombinant CsANR in vitro. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  12. Acetylation regulates protein stability and DNA-binding ability of HilD to modulate Salmonella Typhimurium virulence. (United States)

    Sang, Yu; Ren, Jie; Qin, Ran; Liu, Shuting; Cui, Zhongli; Cheng, Sen; Liu, Xiaoyun; Lu, Jie; Tao, Jing; Yao, Yu-Feng


    HilD, a dominant regulator of Salmonella pathogenicity island 1 (SPI-1), can be acetylated by acetyltransferase Pat in Salmonella Typhimurium, and the acetylation is beneficial to its stability. However, the underlying mechanism of HilD stability regulated by acetylation is not clear. We show here that lysine 297 (K297) located in the helix-turn-helix motif, can be acetylated by Pat. Acetylation of K297 increases HilD stability, but reduces its DNA-binding affinity. In turn, the deacetylated K297 enhances the DNA-binding ability, but decreases HilD stability. Under SPI-1 inducing condition, the acetylation level of K297 is down-regulated. The acetylated K297 (mimicked by glutamine substitution) causes attenuated invasion in HeLa cells as well as impaired virulence in mouse model compared with the deacetylated K297 (mimicked by arginine substitution), suggesting that deacetylation of K297 is essential for Salmonella virulence. These findings demonstrate that the acetylation of K297 can regulate both protein stability and DNA-binding ability. This regulation mediated by acetylation not only degrades redundant HilD to keep a moderate protein level to facilitate S. Typhimurium growth but also maintains an appropriate DNA-binding activity of HilD to ensure bacterial pathogenicity. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail

  13. Betaalpha-hairpin clamps brace betaalphabeta modules and can make substantive contributions to the stability of TIM barrel proteins.

    Directory of Open Access Journals (Sweden)

    Xiaoyan Yang

    Full Text Available Non-local hydrogen bonding interactions between main chain amide hydrogen atoms and polar side chain acceptors that bracket consecutive betaalpha or alphabeta elements of secondary structure in alphaTS from E. coli, a TIM barrel protein, have previously been found to contribute 4-6 kcal mol(-1 to the stability of the native conformation. Experimental analysis of similar betaalpha-hairpin clamps in a homologous pair of TIM barrel proteins of low sequence identity, IGPS from S. solfataricus and E. coli, reveals that this dramatic enhancement of stability is not unique to alphaTS. A survey of 71 TIM barrel proteins demonstrates a 4-fold symmetry for the placement of betaalpha-hairpin clamps, bracing the fundamental betaalphabeta building block and defining its register in the (betaalpha(8 motif. The preferred sequences and locations of betaalpha-hairpin clamps will enhance structure prediction algorithms and provide a strategy for engineering stability in TIM barrel proteins.

  14. Roll-to-roll printed silver nanowires for increased stability of flexible ITO-free organic solar cell modules

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Roth, Bérenger; Corazza, Michael


    We report the use of roll-to-roll printed silver nanowire networks as front electrodes for fully roll-to-roll processed flexible indium-tin-oxide (ITO) free OPV modules. We prepared devices with two types of back electrodes, a simple PEDOT:PSS back electrode and a PEDOT:PSS back electrode with a ...

  15. Soil organic matter (de)stabilization - new experiments needed to inform soil biogeochemistry modules in earth system models (United States)

    Schmidt, Michael W. I.; Torn, Margaret S.; Riley, William J.


    To better predict soil carbon climate feedbacks, the next generation of soil biogeochemistry modules in Earth System Models (ESMs) demand new types of experiments, and a more appropriate use of existing observations. For example, we highlight soil incubations and how they have been misinterpreted when inferring pseudo-first order turnover times and decomposition temperature and moisture sensitivities. Further, for existing pseudo first-order modules, and the new microbial- and mineral-explicit generation of biogeochemistry modules, there is often a mismatch between temporal and spatial observations and how they are used by modelers. Observation periods should be longer, from annual to decadal, and include transitions, e.g., induced by climate or management. Key observations to better structure and parameterize processes that are important for carbon-climate feedbacks include i) mineral surface interactions, ii) microbial dynamics and activity, including effects of soil temperature and moisture, iii) erosion and export, iv) landscape scale process heterogeneity, and v) the effect of land use change, such as clear cut and changes in tillage. Recent insights and knowledge gaps from traditionally disconnected scientific fields (such as geophysical modeling, agricultural soil science, geomorphology, and soil biogeochemistry) will be discussed in the context of informing ESM-scale terrestrial biogeochemistry models.

  16. Time domain modelling and stability analysis of an integral pulse frequency modulated dc to dc power converter (United States)

    Iwens, R. P.; Yu, Y.; Triner, J. E.


    Using state variable representation a nonlinear, discrete-time system is derived that models the converter exactly. This system is linearized about its steady state solution, and converter stability, transient response and audio susceptibility are studied. The steady state solution of the converter is stable if and only if all the roots of the linearized system are absolutely less than unity. Excellent agreement with laboratory test data has been observed.

  17. Enhanced gastric stability of esomeprazole by molecular interaction and modulation of microenvironmental pH with alkalizers in solid dispersion. (United States)

    Van Nguyen, Hien; Baek, Namhyun; Lee, Beom-Jin


    Due to the instability of esomeprazole magnesium dihydrate (EPM), a proton pump inhibitor, in gastric fluid, enteric-coated dosage form is commonly used for therapeutic application. In this study, we prepared new gastric fluid resistant solid dispersions (SDs) containing alkalizers. Then, new mechanistic evidence regarding the effects of pharmaceutical alkalizers on the aqueous stability of EPM in simulated gastric fluid was investigated. The alkalizer-loaded SD were prepared by dissolving or dispersing EPM, hydroxypropyl methylcellulose (HPMC) 6 cps, and an alkalizer, in ethanol 50% (v/v) followed by spray drying. Nine different alkalizers were assessed for in vitro stability in two media, simulated gastric fluid (pH 1.2 buffer) and simulated intestinal fluid (pH 6.8 buffer). The microenvironmental pH (pHM) was measured to evaluate the effect of the alkalizer on the pHM of SDs. Drug crystallinity and morphology of the SDs were also examined by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The interactions among EPM, the polymer, and the alkalizer were elucidated by Fourier transform infrared (FTIR) spectroscopy. The in vivo absorption studies of the optimized alkalizer-containing SD and the enteric-coated reference tablet Nexium® were then conducted in beagle dogs. Among alkalizers, MgO loaded in SDs proved to be the best alkalizer to stabilize EPM in simulated gastric fluid. pHM values of the alkalizer-containing SDs were significantly higher than that of the SD without alkalizer. The pHM values decreased in the following order: MgO, Na2CO3, Ca(OH)2, and no alkalizer. DSC and PXRD data exhibited a change in the drug crystallinity of the SDs from crystalline to amorphous form. SEM data showed a relatively spherical shape of the MgO-loaded SD compared to the less-defined shape of pure drug. FTIR indicated a strong molecular interaction among EPM, alkalizer and polymer; in particular, MgO showed

  18. Stereochemistry of 16a-Hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene Established by 2D NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Vagner Fernandes Knupp


    Full Text Available Friedelin (1, 3b-friedelinol (2, 28-hydroxyfriedelin (3, 16a-hydroxyfriedelin (4, 30-hydroxyfriedelin (5 and 16a,28-dihydroxyfriedelin (6 were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl3 solution, 16a-hydroxyfriedelin (4 reacted turning into 3-oxo-16-methylfriedel-16-ene (7. This is the first report of a dehydration followed by a Nametkin rearrangement of a pentacyclic triterpene in CDCl3 solution occurring in the NMR tube. These seven pentacyclic triterpenes was identified through NMR spectroscopy and the stereochemistry of compound 4 and 7 was established by 2D NMR (NOESY spectroscopy and mass spectrometry (GC-MS. It is also the first time that all the 13C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.

  19. Stereoselective Synthesis of 8,12-Furanoeudesmanes from Santonin. Absolute Stereochemistry of Natural Furanoeudesma-1,3-diene and Tubipofurane. (United States)

    Blay, Gonzalo; Cardona, Luz; García, Begoña; Pedro, José R.; Sánchez, Juan J.


    Ketobutenolide 3, easily obtained from santonin (1), has been transformed into two natural furanoeudesmanes 4 and 5, isolated from Commiphora molmol and Tubipora musica, respectively. trans- And cis-decalin systems were obtained by stereoselective reduction of the C(4)-C(5) double bond in 3 in the following way: hydrogenation of 3 over Pd/C followed by acidic treatment gave the cis isomer 10 as the major product; selective hydrogenation of the C(1)-C(2) double bond with the Wilkinson's catalyst followed by reduction with NaTeH yielded mainly the trans isomer 9. Compounds 9 and 10 were transformed into 4 and 5 in parallel sequences. Optical rotation and CD measurements of the synthetic products revealed that the stereochemistry of both natural products should be revised to their enantiomeric form.

  20. Preparation of starch stabilized silver nanoparticles with spatial self-phase modulation properties by laser ablation technique

    Energy Technology Data Exchange (ETDEWEB)

    Zamiri, Reza; Azmi, B.Z.; Sadrolhosseini, Amir R.; Husin, M.S.; Zaidan, A.W. [Universiti Putra Malaysia, Department of Physics, Faculty of Science, UPM Serdang, Selangor (Malaysia); Darroudi, Majid [Universiti Putra Malaysia, Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, UPM Serdang, Selangor (Malaysia); Mahdi, M.A. [Universiti Putra Malaysia, Wireless and Photonics Networks Research Center, Faculty of Engineering, UPM Serdang, Selangor (Malaysia)


    Silver nanoparticles inside the starch solution have been successfully fabricated by laser ablation of a silver plate immersed in starch solution. The ablation has been done using a Q-switched Nd:YAG laser at 10 Hz repetition rate. The starch solution allows for the formation of silver nanoparticles with uniform particle diameters and well dispersed. The ablation was performed at different time durations to study the influence of the laser ablation time on efficiency of particle formation and sizes. The Spatial Self-phase modulation phenomena which can determine the nonlinear optical property of the samples were also investigated for starch solutions containing silver nanoparticles. (orig.)

  1. Modulation stability and optical soliton solutions of nonlinear Schrödinger equation with higher order dispersion and nonlinear terms and its applications (United States)

    Arshad, Muhammad; Seadawy, Aly R.; Lu, Dianchen


    In optical fibers, the higher order non-linear Schrödinger equation (NLSE) with cubic quintic nonlinearity describes the propagation of extremely short pulses. We constructed bright and dark solitons, solitary wave and periodic solitary wave solutions of generalized higher order NLSE in cubic quintic non Kerr medium by applying proposed modified extended mapping method. These obtained solutions have key applications in physics and mathematics. Moreover, we have also presented the formation conditions on solitary wave parameters in which dark and bright solitons can exist for this media. We also gave graphically the movement of constructed solitary wave and soliton solutions, that helps to realize the physical phenomena's of this model. The stability of the model in normal dispersion and anomalous regime is discussed by using the modulation instability analysis, which confirms that all constructed solutions are exact and stable. Many other such types of models arising in applied sciences can also be solved by this reliable, powerful and effective method.

  2. Glucose-regulated protein 58 modulates β-catenin protein stability in a cervical adenocarcinoma cell line. (United States)

    Liao, Chia-Jung; Wu, Tzu-I; Huang, Ya-Hui; Chang, Ting-Chang; Lai, Chyong-Huey; Jung, Shih-Ming; Hsueh, Chuen; Lin, Kwang-Huei


    Cervical cancer continues to threaten women's health worldwide, and the incidence of cervical adenocarcinoma (AD) is rising in the developed countries. Previously, we showed that glucose-regulated protein 58 (Grp58) served as an independent factor predictive of poor prognosis of patients with cervical AD. However, the molecular mechanism underlying the involvement of Grp58 in cervical carcinogenesis is currently unknown. DNA microarray and enrichment analysis were used to identify the pathways disrupted by knockdown of Grp58 expression. Among the pathway identified, the WNT signaling pathway was one of those that were significantly associated with knockdown of Grp58 expression in HeLa cells. Our experiments showed that β-catenin, a critical effector of WNT signaling, was stabilized thereby accumulated in stable Grp58 knockdown cells. Membrane localization of β-catenin was observed in Grp58 knockdown, but not control cells. Using a transwell assay, we found that accumulated β-catenin induced by Grp58 knockdown or lithium chloride treatment inhibited the migration ability of HeLa cells. Furthermore, an inverse expression pattern of Grp58 and β-catenin was observed in cervical tissues. Our results demonstrate that β-catenin stability is negatively regulated by Grp58 in HeLa cells. Overexpression of Grp58 may be responsible for the loss of or decrease in membranous β-catenin expression in cervical AD.

  3. Modulation of microenvironmental pH and utilization of alkalizers in crystalline solid dispersion for enhanced solubility and stability of clarithromicin. (United States)

    Park, Jun-Bom; Park, Young-Joon; Kang, Chin-Yang; Lee, Beom-Jin


    Clarithromycin (CAM) is known to be poorly water-soluble and acid-labile drug. Various alkalizers such as MgO, Na2CO3, Na2HPO4 and NaHCO3 were utilized to modulate the microenvironmental pH (pHM) and to improve the low stability and solubility of CAM in a crystalline-solid dispersion system (CSD). Polyvinylpyrrolidone (PVP K-30) and hydroxypropylmethylcellulose (HPMC) 4000-based CSDs containing alkalizers were prepared by cosolvent precipitation followed by evaporation process. The dried-CSDs mixed with microcrystalline cellulose, 2% croscarmellose sodium, and 1% magnesium stearate was then directly compressed into tablet. A dissolution test was carried out in 900 mL of pH 5.0 buffer solutions at 37 °C with a 50 rpm paddle speed. pHM, surface morphology, and structural behaviors were investigated. The dissolution rates of CAM in CSD containing alkalizers were improved. The drug in CSD remained crystalline as observed by differential scanning calorimetry and powder X-ray diffraction. Scanning electron microscopy revealed nearly identical images regardless of the sorts and amounts of carriers. PVP-based CSD tablet without alkalizer showed greater drug release, while HPMC-based CSD tablet without alkalizer retarded drug release due to its greater swelling capability. However, when the alkalizers were added in CSD tablet, the drug release was sharply increased. NaHCO3 induced the most rapid drug release while MgO retarded drug dissolution. Alkalizers in CSD also could maintain the pHM of the tablet above pH 5 under acidic conditions. The use of pH modifiers in CSDs could provide a useful method to improve the dissolution rate and stability of CAM via modulation of pHM without changing drug crystallinity.

  4. Lifetime improvement and beam stabilization by longitudinal phase modulation at the DELTA electron storage ring; Lebensdauerverbesserung und Strahlstabilisierung durch longitudinale Phasenmodulation am Elektronenspreicherring DELTA

    Energy Technology Data Exchange (ETDEWEB)

    Fuersch, Jonathan


    In DELTA especially at high beam currents often the occurence of an instability of a longitudinal oscillation mode is observed. In the framework of the present thesis first with different procedure the cause of the longitudinal oscillation mode, which is especially strongly excited at high beam currents, is searched for. Thereby connections between the occurrence of this mode and parameters from the region of the storage-ring high-frequency system is observed. It is shown by comparison of different procedures, simulation calculations, and experimental pre-examinations, that especially by a phase modulation of the storage-ring high frequency an essential improvement of especially the longitudinal beam stability and the beam lifetime can be reached. For the durable and reliable improvement of these beam properties in the framework of the present thesis a system for the longitudinal phase modulation of the after-acceleration voltage in the cavity resonator of the DELTA storage ring is concipated, developed, constructed, taken in operation, and tested. Finally the results aimed hereby are presented and discussed.

  5. Genetics and Molecular Biology of Epstein-Barr Virus-Encoded BART MicroRNA: A Paradigm for Viral Modulation of Host Immune Response Genes and Genome Stability

    Directory of Open Access Journals (Sweden)

    David H. Dreyfus


    Full Text Available Epstein-Barr virus, a ubiquitous human herpesvirus, is associated through epidemiologic evidence with common autoimmune syndromes and cancers. However, specific genetic mechanisms of pathogenesis have been difficult to identify. In this review, the author summarizes evidence that recently discovered noncoding RNAs termed microRNA encoded by Epstein-Barr virus BARF (BamHI A right frame termed BART (BamHI A right transcripts are modulators of human immune response genes and genome stability in infected and bystander cells. BART expression is apparently regulated by complex feedback loops with the host immune response regulatory NF-κB transcription factors. EBV-encoded BZLF-1 (ZEBRA protein could also regulate BART since ZEBRA contains a terminal region similar to ankyrin proteins such as IκBα that regulate host NF-κB. BALF-2 (BamHI A left frame transcript, a viral homologue of the immunoglobulin and T cell receptor gene recombinase RAG-1 (recombination-activating gene-1, may also be coregulated with BART since BALF-2 regulatory sequences are located near the BART locus. Viral-encoded microRNA and viral mRNA transferred to bystander cells through vesicles, defective viral particles, or other mechanisms suggest a new paradigm in which bystander or hit-and-run mechanisms enable the virus to transiently or chronically alter human immune response genes as well as the stability of the human genome.

  6. Modulation of inflammatory gene expression by a bilberry ( Vaccinium myrtillus L.) extract and single anthocyanins considering their limited stability under cell culture conditions. (United States)

    Triebel, Sven; Trieu, Hai-Linh; Richling, Elke


    Studies with nonintestinal models indicate that anthocyanin-rich extracts can modulate inflammatory gene expression and may help prevent development of inflammatory bowel diseases (IBD). This work investigated the influence of a bilberry ( Vaccinium myrtillus L.) extract (BE) and comprising anthocyanins on pro-inflammatory genes in IFN-γ/IL-1β/TNF-α stimulated human colon epithelial cells (T84) by qRT-PCR and cytokine arrays. Moreover, the stability of selected anthocyanins under cell culture conditions was examined to assess their anti-inflammatory properties. BE and single anthocyanins significantly inhibited the expression and secretion of IBD-associated pro-inflammatory mediators (TNF-α, IP-10, I-TAC, sICAM-1, GRO-α) in the stimulated cells. The anti-inflammatory activity thereby strongly depends on the aglycon structure (hydroxylation and methylation pattern) and the sugar moiety. In contrast to anthocyanidins, which were highly unstable in cell culture medium, suggesting that their degradation products might contribute to the inhibitory effects assigned to the parent compounds, anthocyanins have higher stability and may directly contribute to BE's effects.

  7. Dopamine modulation of GABAergic function enables network stability and input selectivity for sustaining working memory in a computational model of the prefrontal cortex. (United States)

    Lew, Sergio E; Tseng, Kuei Y


    Dopamine modulation of GABAergic transmission in the prefrontal cortex (PFC) is thought to be critical for sustaining cognitive processes such as working memory and decision-making. Here, we developed a neurocomputational model of the PFC that includes physiological features of the facilitatory action of dopamine on fast-spiking interneurons to assess how a GABAergic dysregulation impacts on the prefrontal network stability and working memory. We found that a particular non-linear relationship between dopamine transmission and GABA function is required to enable input selectivity in the PFC for the formation and retention of working memory. Either degradation of the dopamine signal or the GABAergic function is sufficient to elicit hyperexcitability in pyramidal neurons and working memory impairments. The simulations also revealed an inverted U-shape relationship between working memory and dopamine, a function that is maintained even at high levels of GABA degradation. In fact, the working memory deficits resulting from reduced GABAergic transmission can be rescued by increasing dopamine tone and vice versa. We also examined the role of this dopamine-GABA interaction for the termination of working memory and found that the extent of GABAergic excitation needed to reset the PFC network begins to occur when the activity of fast-spiking interneurons surpasses 40 Hz. Together, these results indicate that the capability of the PFC to sustain working memory and network stability depends on a robust interplay of compensatory mechanisms between dopamine tone and the activity of local GABAergic interneurons.

  8. The effects of serotonin modulation on medial prefrontal connectivity strength and stability: A pharmacological fMRI study with citalopram. (United States)

    Arnone, D; Wise, T; Walker, C; Cowen, P J; Howes, O; Selvaraj, S


    Static and dynamic functional connectivity are being increasingly used to measure the effects of disease and a range of different interventions on brain networks. While preliminary evidence suggests that static connectivity can be modulated by chronic antidepressants administration in healthy individuals and in major depression, much less is known about the acute effects of antidepressants especially on dynamic functional connectivity changes. Here we examine acute effects of antidepressants on dynamic functional connectivity within the default mode network. The default mode network is a well described network with many functions in which the role of serotonin is not clear. In this work we measured acute pharmacological effects of an infusion of the selective serotonin reuptake inhibitor (SSRI) citalopram 10 mg in a sample of thirteen healthy volunteers randomised to receive on two occasions the active compound or placebo in a cross over dosing. Acute citalopram administration relative to placebo increased static connectivity between the medial prefrontal cortex and right dorsolateral prefrontal cortex and posterior cingulate cortex. The SSRI also induced a reduction in variability of connectivity with the medial prefrontal cortex in the precuneus and posterior cingulate cortex. The measured changes are compatible with modified serotonin cortical availability. Copyright © 2017. Published by Elsevier Inc.

  9. Fat Emulsion Intragastric Stability and Droplet Size Modulate Gastrointestinal Responses and Subsequent Food Intake in Young Adults1234 (United States)

    Hussein, Mahamoud O; Hoad, Caroline L; Wright, Jeff; Singh, Gulzar; Stephenson, Mary C; Cox, Eleanor F; Placidi, Elisa; Pritchard, Susan E; Costigan, Carolyn; Ribeiro, Henelyta; Ciampi, Elisabetta; Nandi, Asish; Hedges, Nick; Sanderson, Paul; Peters, Harry PF; Rayment, Pip; Spiller, Robin C; Gowland, Penny A


    Background: Intragastric creaming and droplet size of fat emulsions may affect intragastric behavior and gastrointestinal and satiety responses. Objectives: We tested the hypotheses that gastrointestinal physiologic responses and satiety will be increased by an increase in intragastric stability and by a decrease in fat droplet size of a fat emulsion. Methods: This was a double-blind, randomized crossover study in 11 healthy persons [8 men and 3 women, aged 24 ± 1 y; body mass index (in kg/m2): 24.4 ± 0.9] who consumed meals containing 300-g 20% oil and water emulsion (2220 kJ) with 1) larger, 6-μm mean droplet size (Coarse treatment) expected to cream in the stomach; 2) larger, 6-μm mean droplet size with 0.5% locust bean gum (LBG; Coarse+LBG treatment) to prevent creaming; or 3) smaller, 0.4-μm mean droplet size with LBG (Fine+LBG treatment). The participants were imaged hourly by using MRI and food intake was assessed by using a meal that participants consumed ad libitum. Results: The Coarse+LBG treatment (preventing creaming in the stomach) slowed gastric emptying, resulting in 12% higher gastric volume over time (P emulsion droplet size can influence human gastrointestinal physiology and food intake. PMID:25926408

  10. Antiinflammatory Effect of Rosiglitazone via Modulation of mRNA Stability of Interleukin 10 and Cyclooxygenase 2 in Astrocytes. (United States)

    Pankevich, E V; Astakhova, A A; Chistyakov, D V; Sergeeva, M G


    Investigation of molecular mechanisms of proinflammatory stimuli signaling in astrocytes is important for understanding their role in pathogenesis of central nervous system diseases as well as in functioning of the innate immunity system in non-immune cells. Here we show that lipopolysaccharide (LPS) stimulation of primary rat astrocytes led to conventional inflammatory response: increase in both proinflammatory (tumor necrosis factor, TNFα; prostaglandin E 2 , PGE 2 ) and antiinflammatory marker (interleukin 10, IL-10) levels. The protein level of cyclooxygenase 2 (COX-2) was also increased. Rosiglitazone strengthened LPS-induced mRNA expression of COX-2 and IL-10 but not TNFα. Rosiglitazone is an agonist of nuclear receptor PPARγ, but its impact on IL-10 expression was not influenced by a PPARγ antagonist, GW9662, suggesting PPARγ-independent effect of rosiglitazone. The degradation of mRNA is one of the steps of inflammation regulation and might be affected by small molecules. In experiments with actinomycin D, we found that mRNA half-lives of IL-10, COX-2, and TNFα in naive astrocytes were 70, 44, and 19 min, respectively. LPS stimulation caused 2-fold increase in IL-10 and COX-2 mRNA decay rates, whereas addition of rosiglitazone restored them to the initial level. TNFα decay rate was not changed by these stimulations. This suggests that mRNA decay rate could be regulated by small molecules. Moreover, rosiglitazone could be used as a substance stimulating the resolution of inflammation without influence on proinflammatory signals. These results open new perspectives in the search for inflammation resolution modulators.


    Directory of Open Access Journals (Sweden)

    Vladimir F. Kupryashkin


    Full Text Available Introduction. The paper is devoted to the theoretical study of stability of movement of the movable unit of the experimental setup intended for the exploration of the active rotational working organs of the car for soil treatment. This takes into account the design features of the mobile unit and features active rotary force interaction of working bodies with the soil. From the analysis of previously conducted both theoretical and experimental studies of this type of working bodies noted the possibility of breaking the stability of the mobile stroke unit, which in turn will have a negative impact on the enforcement of a given method of the experiment program. From the analysis of previous studies shows that the assumptions under which they were made, not allow you to fully take into account the nature of the effect occurring dynamic processes of interaction of active rotary working bodies with the soil on the experimental setup truck driving stability. Materials and Methods. To address the shortcomings in the research, based on a synthesis of the main provisions and laws of mechanics and the experimental data of active rotary force interaction of working bodies with the soil, carried out theoretical studies of stability of movement of the movable unit of the experimental setup in view of its design features and conditions of the experiment. Results. A theoretical study was composed of loading trolley design scheme of the experimental setup with regard to its design features and power factors acting on its working elements, namely, the wheel bearing and studied active rotary working bodies. Processing results of the study allowed the weary twist zone of stable and unstable movement of the movable unit Expo tal installation. The presence of unstable movement zone carts at-leads to a breach of the conditions set by the plan of experimental-governmental research and a negative impact on their quality and purity. Discussion and Conclusions. All of

  12. Imposing function down a (cupin)-barrel: secondary structure and metal stereochemistry in the αKG-dependent oxygenases. (United States)

    Hangasky, John A; Taabazuing, Cornelius Y; Valliere, Meaghan A; Knapp, Michael J


    The Fe(ii)/αketoglutarate (αKG) dependent oxygenases catalyze a diverse range of reactions significant in biological processes such as antibiotic biosynthesis, lipid metabolism, oxygen sensing, and DNA and RNA repair. Although functionally diverse, the eight-stranded β-barrel (cupin) and HX(D/E)XnH facial triad motifs are conserved in this super-family of enzymes. Crystal structure analysis of 25 αKG oxygenases reveals two stereoisomers of the Fe cofactor, Anti and Clock, which differ in the relative position of the exchangeable ligand position and the primary substrate. Herein, we discuss the relationship between the chemical mechanism and the secondary coordination sphere of the αKG oxygenases, within the constraints of the stereochemistry of the Fe cofactor. Sequence analysis of the cupin barrel indicates that a small subset of positions constitute the second coordination sphere, which has significant ramifications for the structure of the ferryl intermediate. The competence of both Anti and Clock stereoisomers of Fe points to a ferryl intermediate that is 5 coordinate. The small number of conserved close contacts within the active sites of αKG oxygenases can be extended to chemically related enzymes, such as the αKG-dependent halogenases SyrB2 and CytC3, and the non-αKG dependent dioxygenases isopenicillin N synthase (IPNS) and cysteine dioxygenase (CDO).

  13. Interplay Of Stereochemistry, Conformational Rigidity, And Ease Of Synthesis For 13-Membered Cyclic Peptidomimetics Containing APC Residues. (United States)

    Xin, Dongyue; Jeffries, Andrew; Burgess, Kevin


    As part of a program to design small molecules that bind proteins, we require cyclic peptides (or peptidomimetics) that are severely constrained such that they adopt one predominant conformation in solution. This paper describes syntheses of the 13-membered cyclic tetrapeptides 1 containing aminopyrrolidine carboxyl (APC) residues. A linear precursor was prepared and used to determine optimal conditions for cyclization of that substrate. A special linker was prepared to enable cyclization of similar linear peptidomimetics on a solid phase, and the solution-phase cyclization conditions were shown to be appropriate for this too. Stereochemical variations were then used to determine the ideal APC configuration for cyclization of the linear precursors (on a solid phase, using the conditions identified previously). Consequently, a series of compounds were prepared that are representative of compounds 1. Conformational studies of representative compounds in DMSO solution were performed primarily using (i) NOE studies, (ii) quenched molecular dynamics simulations using no constraints from experiment, and (iii) MacroModel calculations with NMR constraints. All three strategies converged to the same conclusion: the backbone of molecules based on 1 tends to adopt one preferential conformation in solution and that conformation can be predicted from the stereochemistries of the α-amino acids involved.

  14. Effect of Stereochemistry on Directed Self-Assembly of Poly(styrene-b-lactide) Films on Chemical Patterns

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiao; Liu, Yadong; Wan, Lei; Li, Zhaolei; Suh, Hyoseon; Ren, Jiaxing; Ocola, Leonidas E.; Hu, Wenbing; Ji, Shengxiang; Nealey, Paul F.


    We demonstrated here for the first time that the stereochemistry of polylactide (PLA) blocks affected the assembly behaviors of PS-b-PLA on chemical patterns. Two PS-b-PLA block copolymers, where the PLA block is either racemic (PDLLA) or left-handed (PLLA), were synthesized and directed to assemble on chemical patterns with a wide range of L-s/L-o. PS-b-PDLLA was stretched up to 70% on chemical patterns, while PS-b-PLLA was only stretched by 20%. The assembly behavior of PS-b-PDLLA was different from AB diblock copolymer, but similar to that of ABA triblock copolymer. The high stretchability might be attributed to the formation of stereocomplexes in PDLLA blocks. Compared to ABA triblock copolymers, stereocomplexed diblock copolymers have much faster assembly kinetics. This observation provides a new concept to achieve large process windows by the introduction of specific interactions, for example, H-bonding, supramolecular interaction, and sterecomplexation, between polymer chains.

  15. Effect of sequence and stereochemistry reversal on p53 peptide mimicry.

    Directory of Open Access Journals (Sweden)

    Alessio Atzori

    Full Text Available Peptidomimetics effective in modulating protein-protein interactions and resistant to proteolysis have potential in therapeutic applications. An appealing yet underperforming peptidomimetic strategy is to employ D-amino acids and reversed sequences to mimic a lead peptide conformation, either separately or as the combined retro-inverso peptide. In this work, we examine the conformations of inverse, reverse and retro-inverso peptides of p53(15-29 using implicit solvent molecular dynamics simulation and circular dichroism spectroscopy. In order to obtain converged ensembles for the peptides, we find enhanced sampling is required via the replica exchange molecular dynamics method. From these replica exchange simulations, the D-peptide analogues of p53(15-29 result in a predominantly left-handed helical conformation. When the parent sequence is reversed sequence as either the L-peptide and D-peptide, these peptides display a greater helical propensity, feature reflected by NMR and CD studies in TFE/water solvent. The simulations also indicate that, while approximately similar orientations of the side-chains are possible by the peptide analogues, their ability to mimic the parent peptide is severely compromised by backbone orientation (for D-amino acids and side-chain orientation (for reversed sequences. A retro-inverso peptide is disadvantaged as a mimic in both aspects, and further chemical modification is required to enable this concept to be used fruitfully in peptidomimetic design. The replica exchange molecular simulation approach adopted here, with its ability to provide detailed conformational insights into modified peptides, has potential as a tool to guide structure-based design of new improved peptidomimetics.


    Lucido, Michael J.; Orlando, Benjamin J.; Vecchio, Alex J.; Malkowski, Michael G.


    Aspirin and other nonsterroidal anti-inflammatory drugs target the Cyclooxygenase enzymes (COX-1 and COX-2) to block the formation of prostaglandins. Aspirin is unique in that it covalently modifies each enzyme by acetylating Ser-530 within the cyclooxygenase active site. Acetylation of COX-1 leads to complete loss of activity, while acetylation of COX-2 results in the generation of the mono-oxygenated product 15(R)-hydroxyeicosatetraenoic acid (15R-HETE). Ser-530 has also been shown to influence the stereochemistry for oxygen addition into the prostaglandin product. We determined the crystal structures of S530T murine (mu) COX-2, aspirin-acetylated human (hu) COX-2, and huCOX-2 in complex with salicylate to 1.9Å, 2.0Å, and 2.4Å, respectively. The structures reveal that: 1) the acetylated Ser-530 completely blocks access to the hydrophobic groove; 2) the observed binding pose of salicylate is reflective of the enzyme-inhibitor complex prior to acetylation; and 3) the observed Thr-530 rotamer in the S530T muCOX-2 crystal structure does not impede access to the hydrophobic groove. Based on these structural observations, along with functional analysis of the S530T/G533V double mutant, we propose a working hypothesis for the generation of 15R-HETE by aspirin-acetylated COX-2. We also observe differential acetylation of COX-2 purified in various detergent systems and nanodiscs, indicating that detergent and lipid binding within the membrane-binding domain of the enzyme alters the rate of the acetylation reaction in vitro. PMID:26859324

  17. Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry. (United States)

    Lucido, Michael J; Orlando, Benjamin J; Vecchio, Alex J; Malkowski, Michael G


    Aspirin and other nonsteroidal anti-inflammatory drugs target the cyclooxygenase enzymes (COX-1 and COX-2) to block the formation of prostaglandins. Aspirin is unique in that it covalently modifies each enzyme by acetylating Ser-530 within the cyclooxygenase active site. Acetylation of COX-1 leads to complete loss of activity, while acetylation of COX-2 results in the generation of the monooxygenated product 15(R)-hydroxyeicosatetraenoic acid (15R-HETE). Ser-530 has also been shown to influence the stereochemistry for the addition of oxygen to the prostaglandin product. We determined the crystal structures of S530T murine (mu) COX-2, aspirin-acetylated human (hu) COX-2, and huCOX-2 in complex with salicylate to 1.9, 2.0, and 2.4 Å, respectively. The structures reveal that (1) the acetylated Ser-530 completely blocks access to the hydrophobic groove, (2) the observed binding pose of salicylate is reflective of the enzyme-inhibitor complex prior to acetylation, and (3) the observed Thr-530 rotamer in the S530T muCOX-2 crystal structure does not impede access to the hydrophobic groove. On the basis of these structural observations, along with functional analysis of the S530T/G533V double mutant, we propose a working hypothesis for the generation of 15R-HETE by aspirin-acetylated COX-2. We also observe differential acetylation of COX-2 purified in various detergent systems and nanodiscs, indicating that detergent and lipid binding within the membrane-binding domain of the enzyme alters the rate of the acetylation reaction in vitro.

  18. Scalability and stability of very thin roll-to-roll processed large area indium-tin-oxide free polymer solar cell modules

    DEFF Research Database (Denmark)

    Angmo, Dechan; Gevorgyan, Suren; Larsen-Olsen, Thue Trofod


    Polymer solar cell modules were prepared directly on thin flexible barrier polyethylene terephthalate foil. The performance of the modules was found to be scalable from a single cell with an area of 6 cm2 to modules with a total area of up to 186 cm2. The substrate thickness was also explored...... (ISOS-D-2), under low light (ISOS-LL), under full sunlight (ISOS-L-2), and under outdoor testing (ISOS-O), which was conducted in two locations in India and Denmark. We estimate maximum T80 for those tests to be 2800, 5000, 1300, 1000, and 3500 h respectively. The modules showed significant sensitivity...


    Magnuson, D.W.; Smith, D.F.


    High-frequency oscillators for the generation of microwaves, particularly a system for stabilizing frequency-modulated klystron oscillators of the reflex type, are described. The system takos advantage of the fact that a change in oscillator frequency will alter the normal phase displacement between the cavity and its modulator, creating an error voltage which is utilized to regulate the frequency of the oscillator and stabilize it.

  20. Correlations among experimental and theoretical NMR data to determine the absolute stereochemistry of darcyribeirine, a pentacyclic indole alkaloid isolated from Rauvolfia grandiflora (United States)

    Cancelieri, Náuvia Maria; Ferreira, Thiago Resende; Vieira, Ivo José Curcino; Braz-Filho, Raimundo; Piló-Veloso, Dorila; Alcântara, Antônio Flávio de Carvalho


    Darcyribeirine (1) is a pentacyclic indole alkaloid isolated from Rauvolfia grandiflora. Stereochemistry of 1 was previously proposed based on 1D (coupling constant data) and 2D (NOESY correlations) NMR techniques, having been established a configuration 3R, 15S, and 20R (isomer 1a). Stereoisomers of 1 (i.e., 1a-1h) can be grouped into four sets of enantiomers. Carbon chemical shifts and hydrogen coupling constants were calculated using BLYP/6-31G* theory level for the eight isomers of 1. Calculated NMR data of 1a-1h were correlated with the corresponding experimental data of 1. The best correlations between theoretical and experimental carbon chemical shift data were obtained for the set of enantiomers 1e/1f to structures in the gaseous phase and considering solvent effects (using PCM and explicit models). Similar results were obtained when the same procedure was performed to correlations between theoretical and experimental coupling constant data. Finally, optical rotation calculations indicate 1e as its absolute stereochemistry. Orbital population analysis indicates that the hydrogen bonding between N-H of 1e and DMSO is due to contributions of its frontier unoccupied molecular orbitals, mainly LUMO+1, LUMO+2, and LUMO+3.

  1. Teaching metathesis "simple" stereochemistry. (United States)

    Fürstner, Alois


    Applications of metal-catalyzed olefin metathesis reactions manifested dramatic growth during the late 20th and early 21st centuries, culminating in the 2005 Nobel Prize awarded to three of the pioneers. The standard catalysts developed during that time frame and their descendants have profoundly changed the mindset of the synthetic community, even though they do not provide a handle to control selectivity issues as fundamental as the E/Z geometry of the newly formed double bond. With yet another generation of catalysts in the making that are far superior in this regard, a new wave seems to be building up that is expected to have enormous impact, too. The current state of the art is critically assessed, as are possible alternatives such as the metathesis of triple bonds followed by stereoselective semi-reduction.

  2. Teaching metathesis "simple" stereochemistry

    National Research Council Canada - National Science Library

    Fürstner, Alois


    Applications of metal-catalyzed olefin metathesis reactions manifested dramatic growth during the late 20th and early 21st centuries, culminating in the 2005 Nobel Prize awarded to three of the pioneers...

  3. Stereochemistry Structure of Odonicin

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bao Lin; Li, Jin; Tong, Ling [Shaanxi Normal University, Xian (China); Pan, Yuan Jiang [Zhejiang University, Hangzhou (China); Yu, Kai Bei [Academia Sinica, Chengdu (China)


    Ent-kaurene diterpenoids have various biological activities, such as antitumor, antibacterial, anti-HIV activities etc. The plant of the genus Isodon used in Chinese traditional medicine is a major source of compounds of this structural class. Our investigations on the bitter diterpenoids constituents of the genus Isodon led to the first isolation of odonicin (1) from the leaves and tender branches of Isodon henryi obtained from Taibai Mountain, Shaanxi Province, P. R. China

  4. Effective Stabilization of a High-Loading Sulfur Cathode and a Lithium-Metal Anode in Li-S Batteries Utilizing SWCNT-Modulated Separators. (United States)

    Chang, Chi-Hao; Chung, Sheng-Heng; Manthiram, Arumugam


    A custom single-wall carbon nanotube (SWCNT)-modulated separator is employed to directly suppress the polysulfide migration and indirectly protect the lithium-metal anode from severe polysulfide contamination. The conductive sp(2) -carbon scaffold continuously reactivates and reutilizes the trapped active material, so the SWCNT-modulated separator provides a facile way to facilitate the implementation of pure sulfur cathodes with high sulfur contents and loadings. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Stereochemistry of nucleophilic substitution reactions depending upon substituent: evidence for electrostatic stabilization of pseudoaxial conformers of oxocarbenium ions by heteroatom substituents. (United States)

    Ayala, Leticia; Lucero, Claudia G; Romero, Jan Antoinette C; Tabacco, Sarah A; Woerpel, K A


    Lewis acid-mediated nucleophilic substitution reactions of substituted tetrahydropyran acetates reveal that the conformational preferences of six-membered-ring cations depend significantly upon the electronic nature of the substituent. Nucleophilic substitutions of C-3 and C-4 alkyl-substituted tetrahydropyran acetates proceeded via pseudoequatorially substituted oxocarbenium ions, as would be expected by consideration of steric effects. Substitutions of C-3 and C-4 alkoxy-substituted tetrahydropyran acetates, however, proceeded via pseudoaxially oriented oxocarbenium ions. The unusual selectivities controlled by the alkoxy groups were demonstrated for a range of other heteroatom substituents, including nitrogen, fluorine, chlorine, and bromine. It is believed that the pseudoaxial conformation is preferred in the ground state of the cation because of an electrostatic attraction between the cationic carbon center of the oxocarbenium ion and the heteroatom substituent. This analysis is supported by the observation that selectivity diminishes down the halogen series, which is inconsistent with electron donation as might be expected during anchimeric assistance. The C-2 heteroatom-substituted systems gave moderately high 1,2-cis selectivity, while small alkyl substituents showed no selectivity. Only in the case of the tert-butyl group at C-2 was high 1,2-trans selectivity observed. These studies reinforce the idea that ground-state conformational effects need to be considered along with steric approach considerations.

  6. Over 2 Years of Outdoor Operational and Storage Stability of ITO-free, Fully Roll-to-Roll Fabricated Polymer Solar Cell Modules

    DEFF Research Database (Denmark)

    Angmo, Dechan; Krebs, Frederik C


    and outdoor), all modules maintain the maximum power point (MPP) above T80 (the duration over which a solar cell retains above 80 % of its initial MPP) over two years using a simple low-cost packaging barrier with a water vapor transmission rate (WVTR) of 0.04 g m-2 day-1, an oxygen transmission rate (OTR...

  7. Coating of photovoltaic modules - Effectiveness and stability of various coating methods; Beschichtung von PV-Modulen. Wirksamkeit und Stabilitaet verschiedener Beschichtungsmethoden

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, A.; Leutenegger, S.; Brunold, S.


    This final report for the Swiss Federal Office of Energy (SFOE) discusses the results of a study made on various coating methods for photovoltaic (PV) modules. The results of investigations carried out in parallel are discussed: laboratory investigations for a systematic screening of different glass/coating combinations and a 'real life' investigation in an existing power plant. The results of three years of laboratory investigations are presented and discussed, whereby the authors state that two or even three years of exposition is not long enough for safe conclusions to be drawn. Financing for a further four years of investigation is being discussed. Both investigations have shown that, independent of the coating, regular cleaning of the glass surface has a large impact on the power output of the PV-modules: The significant reduction of power output due to soiling can thus be avoided very effectively.

  8. The tumor suppressor SirT2 regulates cell cycle progression and genome stability by modulating the mitotic deposition of H4K20 methylation (United States)

    The establishment of the epigenetic mark H4K20me1 (monomethylation of H4K20) by PR-Set7 during G2/M directly impacts S-phase progression and genome stability. However, the mechanisms involved in the regulation of this event are not well understood. Here we show that SirT2 regulates H4K20me1 depositi...

  9. Model theory and modules

    CERN Document Server

    Prest, M


    In recent years the interplay between model theory and other branches of mathematics has led to many deep and intriguing results. In this, the first book on the topic, the theme is the interplay between model theory and the theory of modules. The book is intended to be a self-contained introduction to the subject and introduces the requisite model theory and module theory as it is needed. Dr Prest develops the basic ideas concerning what can be said about modules using the information which may be expressed in a first-order language. Later chapters discuss stability-theoretic aspects of module

  10. GCN5L1 modulates cross-talk between mitochondria and cell signaling to regulate FoxO1 stability and gluconeogenesis. (United States)

    Wang, Lingdi; Scott, Iain; Zhu, Lu; Wu, Kaiyuan; Han, Kim; Chen, Yong; Gucek, Marjan; Sack, Michael N


    The mitochondrial enriched GCN5-like 1 (GCN5L1) protein has been shown to modulate mitochondrial protein acetylation, mitochondrial content and mitochondrial retrograde signaling. Here we show that hepatic GCN5L1 ablation reduces fasting glucose levels and blunts hepatic gluconeogenesis without affecting systemic glucose tolerance. PEPCK and G6Pase transcript levels are downregulated in hepatocytes from GCN5L1 liver specific knockout mice and their upstream regulator, FoxO1 protein levels are decreased via proteasome-dependent degradation and via reactive oxygen species mediated ERK-1/2 phosphorylation. ERK inhibition restores FoxO1, gluconeogenic enzyme expression and glucose production. Reconstitution of mitochondrial-targeted GCN5L1 blunts mitochondrial ROS, ERK activation and increases FoxO1, gluconeogenic enzyme expression and hepatocyte glucose production. We suggest that mitochondrial GCN5L1 modulates post-translational control of FoxO1, regulates gluconeogenesis and controls metabolic pathways via mitochondrial ROS mediated ERK activation. Exploring mechanisms underpinning GCN5L1 mediated ROS signaling may expand our understanding of the role of mitochondria in gluconeogenesis control.Hepatic gluconeogenesis is tightly regulated at transcriptional level and is essential for survival during prolonged fasting. Here Wang et al. show that the mitochondrial enriched GCN5-like 1 protein controls hepatic glucose production by regulating FoxO1 protein levels via proteasome-dependent degradation and, in turn, gluconeogenic gene expression.

  11. Stability of modulation transfer function calibration of surface profilometers using binary pseudo-random gratings and arrays with nonideal groove shapes

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitry L.; Yashchuk, Valeriy V.


    The major problem of measurement of a power spectral density (PSD) distribution of surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments, which tends to distort the PSD at higher spatial frequencies. The special mathematical properties of binary pseudo-random patterns make them an ideal basis for developing MTF calibration test surfaces. Two-dimensional binary pseudo-random arrays (BPRAs) have been fabricated and used for the MTF calibration of the MicroMap{trademark}-570 interferometric microscope with all available objectives. An investigation into the effects of fabrication imperfections on the quality of the MTF calibration and a procedure for accounting for such imperfections are presented.

  12. Phosphatidylinositol monophosphate-binding interface in the oomycete RXLR effector AVR3a is required for its stability in host cells to modulate plant immunity. (United States)

    Yaeno, Takashi; Li, Hua; Chaparro-Garcia, Angela; Schornack, Sebastian; Koshiba, Seizo; Watanabe, Satoru; Kigawa, Takanori; Kamoun, Sophien; Shirasu, Ken


    The oomycete pathogen Phytophthora infestans causes potato late blight, one of the most economically damaging plant diseases worldwide. P. infestans produces AVR3a, an essential modular virulence effector with an N-terminal RXLR domain that is required for host-cell entry. In host cells, AVR3a stabilizes and inhibits the function of the E3 ubiquitin ligase CMPG1, a key factor in host immune responses including cell death triggered by the pathogen-derived elicitor protein INF1 elicitin. To elucidate the molecular basis of AVR3a effector function, we determined the structure of Phytophthora capsici AVR3a4, a close homolog of P. infestans AVR3a. Our structural and functional analyses reveal that the effector domain of AVR3a contains a conserved, positively charged patch and that this region, rather than the RXLR domain, is required for binding to phosphatidylinositol monophosphates (PIPs) in vitro. Mutations affecting PIP binding do not abolish AVR3a recognition by the resistance protein R3a but reduce its ability to suppress INF1-triggered cell death in planta. Similarly, stabilization of CMPG1 in planta is diminished by these mutations. The steady-state levels of non-PIP-binding mutant proteins in planta are reduced greatly, although these proteins are stable in vitro. Furthermore, overexpression of a phosphatidylinositol phosphate 5-kinase results in reduction of AVR3a levels in planta. Our results suggest that the PIP-binding ability of the AVR3a effector domain is essential for its accumulation inside host cells to suppress CMPG1-dependent immunity.

  13. Polydatin (PD) inhibits IgE-mediated passive cutaneous anaphylaxis in mice by stabilizing mast cells through modulating Ca{sup 2+} mobilization

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Meichun [Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen 518060 (China); Department of Physiology, Hubei University of Medicine, Shiyan (China); Li, Jianjie [State Key Laboratory of Respiratory Disease for Allergy at Shengzhen University, Shenzhen 518060 (China); Lv, Jingzhang [Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045 (China); Mo, Xucheng; Yang, Chengbin [State Key Laboratory of Respiratory Disease for Allergy at Shengzhen University, Shenzhen 518060 (China); Chen, Xiangdong [Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen 518060 (China); Liu, Zhigang [State Key Laboratory of Respiratory Disease for Allergy at Shengzhen University, Shenzhen 518060 (China); Liu, Jie, E-mail: [Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen 518060 (China)


    Mast cells play a key role in the pathogenesis of asthma and are a promising target for therapeutic intervention in asthma. This study investigated the effects of polydatin (PD), a resveratrol glucoside, on mast cell degranulation upon cross-linking of the high-affinity IgE receptors (FcεRI), as well as the anti-allergic activity of PD in vivo. Herein, we demonstrated that PD treatment for 30 min suppressed FcεRI-mediated mast cell degranulation in a dose-dependent manner. Concomitantly, PD significantly decreased FcεRI-mediated Ca{sup 2+} increase in mast cells. The suppressive effects of PD on FcεRI-mediated Ca{sup 2+} increase were largely inhibited by using LaCl{sub 3} to block the Ca{sup 2+} release-activated Ca{sup 2+} channels (CRACs). Furthermore, PD significantly inhibited Ca{sup 2+} entry through CRACs evoked by thapsigargin (TG). Knocking down protein expression of Orai1, the pore-forming subunit of CRACs, significantly decreased PD suppression of FcεRI-induced intracellular Ca{sup 2+} influx and mast cell degranulation. In a mouse model of mast cell-dependent passive cutaneous anaphylaxis (PCA), in vivo PD administration suppressed mast cell degranulation and inhibited anaphylaxis. Taken together, our data indicate that PD stabilizes mast cells by suppressing FcεRI-induced Ca{sup 2+} mobilization mainly through inhibiting Ca{sup 2+} entry via CRACs, thus exerting a protective effect against PCA. -- Highlights: ► Polydatin can prevent the pathogenesis of passive cutaneous anaphylaxis in mice. ► Polydatin stabilizes mast cells by decreasing FcεRI-mediated degranulation. ► Polydatin suppresses Ca{sup 2+} entry through CRAC channels in mast cells.

  14. Dandelion PPO-1/PPO-2 domain-swaps: the C-terminal domain modulates the pH optimum and the linker affects SDS-mediated activation and stability. (United States)

    Leufken, Christine M; Moerschbacher, Bruno M; Dirks-Hofmeister, Mareike E


    Plant polyphenol oxidases (PPOs) have a conserved three-domain structure: (i) the N-terminal domain (containing the active site) is connected via (ii) a linker to (iii) the C-terminal domain. The latter covers the active site, thereby maintaining the enzyme in a latent state. Activation can be achieved with SDS but little is known about the mechanism. We prepared domain-swap variants of dandelion PPO-1 and PPO-2 to test the specific functions of individual domains and their impact on enzyme characteristics. Our experiments revealed that the C-terminal domain modulates the pH optimum curve and has a strong influence on the optimal pH value. The linker determines the SDS concentration required for full activation. It also influences the SDS concentration required for half maximal activation (kSDS) and the stability of the enzyme during prolonged incubation in buffers containing SDS, but the N-terminal domain has the strongest effect on these parameters. The N-terminal domain also determines the IC50 of SDS and the stability in buffers containing or lacking SDS. We propose that the linker and C-terminal domain fine-tune the activation of plant PPOs. The C-terminal domain adjusts the pH optimum and the linker probably contains an SDS-binding/interaction site that influences inactivation and determines the SDS concentration required for activation. For the first time, we have determined the influence of the three PPO domains on enzyme activation and stability providing insight into the regulation and activation mechanisms of type-3 copper proteins in general. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. ns2np4 (n = 4, 5) lone pair triplets whirling in M*F2E3 (M* = Kr, Xe): Stereochemistry and ab initio analyses (United States)

    Galy, Jean; Matar, Samir F.


    The stereochemistry of ns2np4 (n = 4, 5) lone pair LP characterizing noble gas Kr and Xe (labeled M*) in M*F2 difluorides is examined within coherent crystal chemistry and ab initio visualizations. M*2+ in such oxidation state brings three lone pairs (E) and difluorides are formulated M*F2E3. The analyses use electron localization function (ELF) obtained within density functional theory calculations showing the development of the LP triplets whirling {E3} quantified in the relevant chemical systems. Detailed ELF data analyses allowed showing that in α KrF2E3 and isostructural XeF2E3 difluorides the three E electronic clouds merge or hybridize into a torus and adopt a perfect gyration circle with an elliptical section, while in β KrF2 the network architecture deforms the whole torus into an ellipsoid shape. Original precise metrics are provided for the torus in the different compounds under study. In KrF2 the geometric changes upon β → α phase transition is schematized and mechanisms for the transformation with temperature or pressure are proposed. The results are further highlighted by electronic band structure calculations which show similar features of equal band gaps of 3 eV in both α and β KrF2 and a reorganization of frontier orbitals due to the different orientations of the F-Kr-F linear molecule in the two tetragonal structures.

  16. Excess Dark Currents and Transients in Thin-Film CdTe Solar Cells: Implications for Cell Stability and Encapsulation of Scribe Lines and Cell Ends in Modules

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, T. J.; Berniard, T. J.; Albin, D. S.; Demtsu, S. H.


    We have isolated a non-linear, metastable, shunt-path failure mechanism located at the CdS/CdTe cell edge. In such cases, most performance loss, usually erratic, can be associated with the shunt path. We studied these shunt paths using dark current-transients and infrared (ir) imaging and find only one shunt path per cell and only at the cell corner wall, even in badly degraded cells. The effect on diminishing the cell's efficiency far exceeds what would be expected from the cell's linear shunt-resistance value. We propose that current transients and ir imaging be used as a ''fingerprint'' of the source and magnitude of excess currents to evaluate the contribution of scribe-line edges and cell ends in thin-film module performance and degradation due to environmental stress. Protection afforded by, or contamination due to, new or currently used encapsulants can then be evaluated.

  17. Modulation of Cytokine Production by Drugs with Antiepileptic or Mood Stabilizer Properties in Anti-CD3- and Anti-CD40-Stimulated Blood In Vitro

    Directory of Open Access Journals (Sweden)

    Hubertus Himmerich


    Full Text Available Increased cytokine production possibly due to oxidative stress has repeatedly been shown to play a pivotal role in the pathophysiology of epilepsy and bipolar disorder. Recent in vitro and animal studies of valproic acid (VPA report antioxidative and anti-inflammatory properties, and suppression of interleukin (IL-6 and tumor necrosis factor (TNF-α. We tested the effect of drugs with antiepileptic or mood stabilizer properties, namely, primidone (PRM, carbamazepine (CBZ, levetiracetam (LEV, lamotrigine (LTG, VPA, oxcarbazepine (OXC, topiramate (TPM, phenobarbital (PB, and lithium on the production of the following cytokines in vitro: interleukin (IL-1β, IL-2, IL-4, IL-6, IL-17, IL-22, and TNF-α. We performed a whole blood assay with stimulated blood of 14 healthy female subjects. Anti-human CD3 monoclonal antibody OKT3, combined with 5C3 antibody against CD40, was used as stimulant. We found a significant reduction of IL-1 and IL-2 levels with all tested drugs other than lithium in the CD3/5C3-stimulated blood; VPA led to a decrease in IL-1β, IL-2, IL-4, IL-6, IL-17, and TNF-α production, which substantiates and adds knowledge to current hypotheses on VPA’s anti-inflammatory properties.

  18. Systematic modulation and enhancement of CO{sub 2} : N{sub 2} selectivity and water stability in an isoreticular series of bio-MOF-11 analogues

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tao; Chen, De-Li; Sullivan, Jeanne E.; Kozlowski, Mark T.; Johnson, J Karl; Rosi, Nathaniel L.


    An isoreticular series of cobalt-adeninate bio-MOFs (bio-MOFs 11-14) is reported. The pores of bio-MOFs 11-14 are decorated with acetate, propionate, butyrate, and valerate, respectively. The nitrogen (N{sub 2}) and carbon dioxide (CO{sub 2}) adsorption properties of these materials are studied and compared. The isosteric heats of adsorption for CO{sub 2} are calculated, and the CO{sub 2}:N{sub 2} selectivities for each material are 10 determined. As the lengths of the aliphatic chains decorating the pores in bio-MOFs 11-14 increase, the BET surface areas decrease from 1148 m{sup 2}/g to 17 m{sup 2}/g while the CO{sub 2}:N{sub 2} selectivities predicted from ideal adsorbed solution theory at 1 bar and 273 K for a 10:90 CO{sub 2}:N{sub 2} mixture range from 73:1 for bio-MOF-11 to 123:1 for bio-MOF-12 and finally to 107:1 for bio-MOF-13. At 298 K, the selectivities are 43:1 for bio-MOF-11, 52:1 for bio-MOF-12, and 40:1 for bio-MOF-13. Additionally, it is shown that 15 bio-MOF-14 exhibits a unique molecular sieving property that allows it to adsorb CO{sub 2} but not N{sub 2} at 273 and 298 K. Finally, the water stability of bio-MOFs 11-14 increases with increasing aliphatic chain length. Bio-MOF-14 exhibits no loss of crystallinity or porosity after soaking in water for one month.

  19. Genome-wide array-CGH analysis reveals YRF1 gene copy number variation that modulates genetic stability in distillery yeasts. (United States)

    Deregowska, Anna; Skoneczny, Marek; Adamczyk, Jagoda; Kwiatkowska, Aleksandra; Rawska, Ewa; Skoneczna, Adrianna; Lewinska, Anna; Wnuk, Maciej


    Industrial yeasts, economically important microorganisms, are widely used in diverse biotechnological processes including brewing, winemaking and distilling. In contrast to a well-established genome of brewer's and wine yeast strains, the comprehensive evaluation of genomic features of distillery strains is lacking. In the present study, twenty two distillery yeast strains were subjected to electrophoretic karyotyping and array-based comparative genomic hybridization (array-CGH). The strains analyzed were assigned to the Saccharomyces sensu stricto complex and grouped into four species categories: S. bayanus, S. paradoxus, S. cerevisiae and S. kudriavzevii. The genomic diversity was mainly revealed within subtelomeric regions and the losses and/or gains of fragments of chromosomes I, III, VI and IX were the most frequently observed. Statistically significant differences in the gene copy number were documented in six functional gene categories: 1) telomere maintenance via recombination, DNA helicase activity or DNA binding, 2) maltose metabolism process, glucose transmembrane transporter activity; 3) asparagine catabolism, cellular response to nitrogen starvation, localized in cell wall-bounded periplasmic space, 4) siderophore transport, 5) response to copper ion, cadmium ion binding and 6) L-iditol 2- dehydrogenase activity. The losses of YRF1 genes (Y' element ATP-dependent helicase) were accompanied by decreased level of Y' sequences and an increase in DNA double and single strand breaks, and oxidative DNA damage in the S. paradoxus group compared to the S. bayanus group. We postulate that naturally occurring diversity in the YRF1 gene copy number may promote genetic stability in the S. bayanus group of distillery yeast strains.

  20. Histidine Residues in the Na+-coupled Ascorbic Acid Transporter-2 (SVCT2) Are Central Regulators of SVCT2 Function, Modulating pH Sensitivity, Transporter Kinetics, Na+ Cooperativity, Conformational Stability, and Subcellular Localization* (United States)

    Ormazabal, Valeska; Zuñiga, Felipe A.; Escobar, Elizabeth; Aylwin, Carlos; Salas-Burgos, Alexis; Godoy, Alejandro; Reyes, Alejandro M.; Vera, Juan Carlos; Rivas, Coralia I.


    Na+-coupled ascorbic acid transporter-2 (SVCT2) activity is impaired at acid pH, but little is known about the molecular determinants that define the transporter pH sensitivity. SVCT2 contains six histidine residues in its primary sequence, three of which are exofacial in the transporter secondary structure model. We used site-directed mutagenesis and treatment with diethylpyrocarbonate to identify histidine residues responsible for SVCT2 pH sensitivity. We conclude that five histidine residues, His109, His203, His206, His269, and His413, are central regulators of SVCT2 function, participating to different degrees in modulating pH sensitivity, transporter kinetics, Na+ cooperativity, conformational stability, and subcellular localization. Our results are compatible with a model in which (i) a single exofacial histidine residue, His413, localized in the exofacial loop IV that connects transmembrane helices VII-VIII defines the pH sensitivity of SVCT2 through a mechanism involving a marked attenuation of the activation by Na+ and loss of Na+ cooperativity, which leads to a decreased Vmax without altering the transport Km; (ii) exofacial histidine residues His203, His206, and His413 may be involved in maintaining a functional interaction between exofacial loops II and IV and influence the general folding of the transporter; (iii) histidines 203, 206, 269, and 413 affect the transporter kinetics by modulating the apparent transport Km; and (iv) histidine 109, localized at the center of transmembrane helix I, might be fundamental for the interaction of SVCT2 with the transported substrate ascorbic acid. Thus, histidine residues are central regulators of SVCT2 function. PMID:20843809

  1. Investigation of the effect of sugar stereochemistry on biologically relevant lyotropic phases from branched-chain synthetic glycolipids by small-angle X-ray scattering. (United States)

    Zahid, N Idayu; Conn, Charlotte E; Brooks, Nicholas J; Ahmad, Noraini; Seddon, John M; Hashim, Rauzah


    Synthetic branched-chain glycolipids are suitable as model systems in understanding biological cell membranes, particularly because certain natural lipids possess chain branching. Herein, four branched-chain glycopyranosides, namely, 2-hexyl-decyl-α-D-glucopyranoside (α-Glc-OC10C6), 2-hexyl-decyl-β-D-glucopyranoside (β-Glc-OC10C6), 2-hexyl-decyl-α-D-galactopyranoside (α-Gal-OC10C6), and 2-hexyl-decyl-β-D-galactopyranoside (β-Gal-OC10C6), with a total alkyl chain length of 16 carbon atoms have been synthesized, and their phase behavior has been studied. The partial binary phase diagrams of these nonionic surfactants in water were investigated by optical polarizing microscopy (OPM) and small-angle X-ray scattering (SAXS). The introduction of chain branching in the hydrocarbon chain region is shown to result in the formation of inverse structures such as inverse hexagonal and inverse bicontinuous cubic phases. A comparison of the four compounds showed that they exhibited different polymorphism, especially in the thermotropic state, as a result of contributions from anomeric and epimeric effects according to their stereochemistry. The neat α-Glc-OC10C6 compound exhibited a lamellar (Lα) phase whereas dry α-Gal-OC10C6 formed an inverse bicontinuous cubic Ia3d (QII(G)) phase. Both β-anomers of glucoside and galactoside adopted the inverse hexagonal phase (HII) in the dry state. Generally, in the presence of water, all four glycolipids formed inverse bicontinuous cubic Ia3d (QII(G)) and Pn3m (QII(D)) phases over wide temperature and concentration ranges. The formation of inverse nonlamellar phases by these Guerbet branched-chain glycosides confirms their potential as materials for novel biotechnological applications such as drug delivery and crystallization of membrane proteins.

  2. Mass spectrometric analysis of oxygenations in aromatization of androst-4-ene-3,6,17-trione, a suicide substrate of aromatase, by placental microsomes. Isotope effect and stereochemistry. (United States)

    Numazawa, Mitsuteru; Takahashi, Madoka; Nagaoka, Masao; Handa, Wakako; Yamashita, Kouwa


    Aromatase catalyzes the conversion of androstenedione (AD) to estrone through three sequential oxygenations of the 19-methyl group. 6-OxoAD (1) is one of the typical suicide substrates of aromatase, which is converted by aromatase to 6-oxoestrone through 19-alcohol (19-ol) and 19-aldehyde (19-al) intermediates 2 and 3. To study the deuterium isotope effect on the conversion of 19-ol 2 to 19-al 3 as well as the stereochemistry of the 19-hydrogen removal in this conversion, we initially synthesized [19,19-(2)H(2)] and [19S- or 19R-(2)H] 19-ols 2, starting from the corresponding deuterium-labeled 19-hydroxyAD derivatives. In incubation of non-labeled and [19,19-(2)H(2)]-labeled 19-ol 2 or that of their 1:1 mixture with human placental microsomes in the presence of NADPH under air, there was no significant deuterium-isotope effect on the production of the aromatized product 6-oxoestrone or on the conversion of 19-ol 2 to 19-al 3, based on gas chromatography-mass spectrometric analysis of the estrogen product or liquid chromatography-mass spectrometric (LC-MS) analysis of the deuterium contents of the product 19-al 3 and the recovered 19-ol 2. Moreover, in the incubations of [19S-(2)H] 19-ol 2 and its 19R isomer, LC-MS analysis of the product 3 demonstrated that the 19-pro-R hydrogen atom was stereospecifically removed in the conversion of 19-ol 2 to 19-al 3. These findings indicate that the 19-oxygenation of 19-ol 2 would proceed in the same mechanism as that involved in the AD aromatization.

  3. Synthetic cathinones and stereochemistry: S enantiomer of mephedrone reduces anxiety- and depressant-like effects in cocaine- or MDPV-abstinent rats. (United States)

    Philogene-Khalid, Helene L; Hicks, Callum; Reitz, Allen B; Liu-Chen, Lee-Yuan; Rawls, Scott M


    The neuropharmacological profile of the synthetic cathinone mephedrone (MEPH) is influenced by stereochemistry. Both MEPH enantiomers are monoamine transporter substrates, but R-MEPH is primarily responsible for rewarding effects of MEPH as it produces greater locomotor activation and intracranial self-stimulation than S-MEPH. S-MEPH is a 50-fold more potent 5-HT releaser than R-MEPH and does not place preference in rats. MEPH is also structurally similar to the cathinone derivative bupropion, an antidepressant and smoking cessation medication, suggesting MEPH has therapeutic and addictive properties. We tested the hypothesis that S-MEPH reduces anxiety- and depression-like behaviors in rats withdrawn from chronic cocaine or methylenedioxypyrovalerone (MDPV) using the elevated plus maze (EPM) and forced swim test (FST), respectively. Rats were tested 48-h after a binge-like paradigm (3×/day for 10days in 1-h intervals) of cocaine (10mg/kg), MDPV (1mg/kg) or saline. In vitro studies assessed the receptor binding and activity of S-MEPH. Rats withdrawn from chronic cocaine or MDPV displayed an increase in anxiety- and depression-like behaviors that was antagonized by treatment with S-MEPH (10, 30mg/kg). S-MEPH displayed affinity, but not agonist activity, for 5-HT 2 receptors (2A-2C) and showed negligible affinity for dopaminergic, adrenergic and nicotinic receptors. S-MEPH attenuated withdrawal behaviors following chronic cocaine or MDPV, perhaps through 5-HT release and/or 5-HT 2 receptor interactions. The present data suggest S-MEPH may be a possible structural and pharmacological template to develop maintenance therapy for acute anxiety and depression during early withdrawal from psychostimulant abuse. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Intelligent passively stabilized quadrotor (United States)

    Sayfeddine, D.; Bulgakov, A. G.; Kruglova, T. N.


    Quadrotor stability is one of the most topical researches worldwide. It is due to the simplicity, availability and cost of such platform. This miniature aerial vehicle is highly manoeuvrable, straight forward to use and to maintain. It can be deployed to perform wide variety of tasks. On the other hand, the quadrotor suffers from non-stability, which makes it unreliable, especially when flying on low speed, high altitude and in windy circumstances. This paper discusses the improvement of the quadrotor by adding a stabilizing mechanism working as a passive breaking system in sharp and spontaneous turns. The mechanism is described and simulated as a standalone module. The end result represents the determination of the stiffness coefficient of the stabilizing actuator using fuzzy logic controller.

  5. P(HPMA)-block-P(LA) copolymers in paclitaxel formulations: polylactide stereochemistry controls micellization, cellular uptake kinetics, intracellular localization and drug efficiency. (United States)

    Barz, Matthias; Armiñán, Ana; Canal, Fabiana; Wolf, Florian; Koynov, Kaloian; Frey, Holger; Zentel, Rudolf; Vicent, María J


    In order to explore the influence of polymer microstructure and stereochemistry in biological settings, the synthesis, micellization, cellular fate and the use in paclitaxel formulations of poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(L-lactide) (P(HPMA)-block-P(LLA)) and poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(DL-lactide) block copolymers (P(HPMA)-block-P(DLLA)) were studied. To this end, P(HPMA)-block-P(lactide) block copolymers and their fluorescently labeled analogues were synthesized. The polymers exhibited molecular weights M(n) around 20,000 g/mol with dispersities (D=M(w)/M(n)) below 1.3. In addition, the solution conformation of this new type of partially degradable amphiphilic block copolymers was studied with and without paclitaxel loading in PBS buffer (pH 7.2), employing fluorescence correlation spectroscopy (FCS). We observed polymeric micelles with a hydrodynamic diameter of 17.0 nm for a fluorescently labeled P(HPMA)-block-P(LLA) block copolymer (P2*) and 20.4 nm for a P(HPMA)-block-P(DLLA) block copolymer (P3*). For the corresponding loaded block copolymers aggregates with a diameter of 40.0 nm (P2*) and 41.4 nm (P3*) in formulations containing 17 wt.% paclitaxel were observed, respectively. While the block copolymer itself showed non-toxic behavior up to a concentration of 3 mg/mL in HeLa (human cervix adenocarcinoma) cells, the paclitaxel containing formulations showed IC 50 values in the range of 10-100 nM. The P(HPMA)-block-P(DLLA) polymer (P3*) enters the cells more efficiently than stereo regular polymer (P2*) via an energy-dependent uptake mechanism. Thus, differences in the IC(50) value are--most likely--attributed to significant changes in cellular uptake. Polymer tacticity and stereoregularity appear to represent a key feature determining cellular uptake and efficiency for the PLA block copolymer drug formulations. This work demonstrates the importance of the microstructure of polymers used in drug delivery systems (DDS

  6. Synthesis, characterisation, stereochemistry and antimicrobial ...

    Indian Academy of Sciences (India)

    Abstract. Three 1,5-benzodiazepines viz., N5-chloroacetyl-, N5-piperazinoacetyl- and N5-morpholinoacetyl-. 2,2,4-trimethyl-1H-1,5-benzodiazepines have been synthesized. The structural characterisation and the con- formational preferences of the compounds have been carried out using IR, 1D and 2D NMR spectral data.

  7. Synthesis, characterisation, stereochemistry and antimicrobial ...

    Indian Academy of Sciences (India)

    morpholinoacetyl-2,2,4-trimethyl-1H-1,5-benzodiazepines have been synthesized. The structural characterisation and the conformational preferences of the compounds have been carried out using IR, 1D and 2D NMR spectral data. The NMR ...


    NARCIS (Netherlands)



    The plant enzyme hevamine has both chitinase and lysozyme activity. HPLC analysis of the products of the hydrolysis of chitopentaose shows that hevamine acts with retention of the configuration, despite the absence of a nucleophilic or stabilizing carboxylate. To analyze the stabilization of a

  9. Universal Stabilization of a Parametrically Coupled Qubit (United States)

    Lu, Yao; Chakram, S.; Leung, N.; Earnest, N.; Naik, R. K.; Huang, Ziwen; Groszkowski, Peter; Kapit, Eliot; Koch, Jens; Schuster, David I.


    We autonomously stabilize arbitrary states of a qubit through parametric modulation of the coupling between a fixed frequency qubit and resonator. The coupling modulation is achieved with a tunable coupling design, in which the qubit and the resonator are connected in parallel to a superconducting quantum interference device. This allows for quasistatic tuning of the qubit-cavity coupling strength from 12 MHz to more than 300 MHz. Additionally, the coupling can be dynamically modulated, allowing for single-photon exchange in 6 ns. Qubit coherence times exceeding 20 μ s are maintained over the majority of the range of tuning, limited primarily by the Purcell effect. The parametric stabilization technique realized using the tunable coupler involves engineering the qubit bath through a combination of photon nonconserving sideband interactions realized by flux modulation, and direct qubit Rabi driving. We demonstrate that the qubit can be stabilized to arbitrary states on the Bloch sphere with a worst-case fidelity exceeding 80%.

  10. Visual stability. (United States)

    Melcher, David


    Our vision remains stable even though the movements of our eyes, head and bodies create a motion pattern on the retina. One of the most important, yet basic, feats of the visual system is to correctly determine whether this retinal motion is owing to real movement in the world or rather our own self-movement. This problem has occupied many great thinkers, such as Descartes and Helmholtz, at least since the time of Alhazen. This theme issue brings together leading researchers from animal neurophysiology, clinical neurology, psychophysics and cognitive neuroscience to summarize the state of the art in the study of visual stability. Recently, there has been significant progress in understanding the limits of visual stability in humans and in identifying many of the brain circuits involved in maintaining a stable percept of the world. Clinical studies and new experimental methods, such as transcranial magnetic stimulation, now make it possible to test the causal role of different brain regions in creating visual stability and also allow us to measure the consequences when the mechanisms of visual stability break down.

  11. Macroeconomic stability

    DEFF Research Database (Denmark)

    Jespersen, Jesper


    It is demonstrated that full employment and sustainable development not necessarily are conflicting goals. On the other hand macroeconomic stability cannot be obtained without a deliberate labour sharing policy and a shift in the composition of private consumption away from traditional material...

  12. Stability study of Raloxifene tablets

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Rodríguez Chanfrau

    Full Text Available Introduction: Raloxifene is a selective estrogen receptor modulator from the benzothiophene family. Several clinical trials have shown that raloxifene reduces bone loss rate in the spinal column and may increase bone mass at certain sites. Objective: to determine the physical and chemical stabilities of raloxifene tablets. Methods. three pilot scale batches of 5 kg each were prepared. In vitro dissolution, chemical stability, photostability and humidity studies were carried out. Samples were collected at 0, 1, 2, 3 and 6 months for the accelerated stability study and at 0, 6, 12, 18 and 24 months for the shelf life stability study. Chemical stability was determined using high performance liquid chromatography analytical method, which was developed and validated prior to the study. Results: in the accelerated stability study, the percentages of dissolved drug were more than 90 % and drug content porcentages were between 90 % and 110 %. Humidity conditions affected the chemical stability of the tablets. Conclusions: All raloxifene tablet batches formulations were stable for 24 months in the studied containers stored at 32 ± 2 ºC and waterproof. In vitro drug release dissolution showed good results for 24 months.

  13. An NMR-Smell Module for the First-Semester General Chemistry Laboratory (United States)

    Uffelman, Erich S.; Cox, Elizabeth H.; Brown Goehring, J.; Lorig, Tyler S.; Davis, C. Michele


    This article describes a module of NMR-smell experiments for the general chemistry laboratory that can be taught in two-week or three-week formats; the module has also been run in a modified form with high school students during the summer. The series of experiments involves an exploration of organic stereochemistry via hands-on model building, several chemosensory smell tests, and hands-on use of 13C NMR, thus serving as a powerful interdisciplinary lab involving chemistry, physics, and neuroscience. Similarities and differences between NMR and MRI methods are emphasized. By the end of the NMR-smell module, students have a very basic knowledge of the physics of the NMR process, the ability to identify different types of organic isomerism, the ability to identify stereogenic centers in molecules, and a basic knowledge of the importance of 3-D structure in chemistry. The less quantifiable, but in some ways more important, benefits of the module that students really appreciate are getting to "touch and play" with the NMR, running the smell tests and seeing the strengths and limitations of their noses as analytical instruments, and seeing how the basic chemistry and physics of NMR relate to MRI.

  14. Convergent actions of I kappa B kinase beta and protein kinase C delta modulate mRNA stability through phosphorylation of 14-3-3 beta complexed with tristetraprolin

    NARCIS (Netherlands)

    Gringhuis, Sonja I.; García-Vallejo, Juan Jesús; van het Hof, Bert; van Dijk, Willem


    Regulation of gene expression at the level of mRNA stability is a major topic of research; however, knowledge about the regulatory mechanisms affecting the binding and function of AU-rich element (ARE)-binding proteins (AUBPs) in response to extracellular signals is minimal. The

  15. Thermionic modules (United States)

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.


    Modules of assembled microminiature thermionic converters (MTCs) having high energy-conversion efficiencies and variable operating temperatures manufactured using MEMS manufacturing techniques including chemical vapor deposition. The MTCs incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. The MTCs also exhibit maximum efficiencies of just under 30%, and thousands of the devices and modules can be fabricated at modest costs.

  16. Memory Modulation

    NARCIS (Netherlands)

    Roozendaal, Benno; McGaugh, James L.


    Our memories are not all created equally strong: Some experiences are well remembered while others are remembered poorly, if at all. Research on memory modulation investigates the neurobiological processes and systems that contribute to such differences in the strength of our memories. Extensive

  17. Module descriptor

    DEFF Research Database (Denmark)

    Vincenti, Gordon; Klausen, Bodil; Kjær Jensen, Jesper


    The Module Descriptor including a Teacher’s Guide explains and describes how to work innovatively and co-creatively with wicked problems and young people. The descriptor shows how interested educators and lecturers in Europe can copy the lessons of the Erasmus+ project HIP when teaching their own...

  18. Before Stabilization

    DEFF Research Database (Denmark)

    Plesner, Ursula; Horst, Maja


    of the communication about innovations in information and communication technology (ICT), and to contribute to an understanding of how different visions promise particular future configurations of workflows, communication processes, politics, economic models and social relations. Hereby, the paper adds...... to the literature on the relationship between ICTs and organizing, but with a distinct focus on innovation communication and distributed innovation processes taking place before ICTs are stabilized, issues which cannot be captured by studies of diffusion and adaptation of new ICTs within single organizations....

  19. Toblerols: Cyclopropanol-Containing Polyketide Modulators of Antibiosis in Methylobacteria. (United States)

    Ueoka, Reiko; Bortfeld-Miller, Miriam; Morinaka, Brandon I; Vorholt, Julia A; Piel, Jörn


    Trans-AT polyketide synthases (PKSs) are a family of biosynthetically versatile modular type I PKSs that generate bioactive polyketides of impressive structural diversity. In this study, we detected, in the genome of several bacteria a cryptic, architecturally unusual trans-AT PKS gene cluster which eluded automated PKS prediction. Genomic mining of one of these strains, the model methylotroph Methylobacterium extorquens AM1, revealed unique epoxide- and cyclopropanol-containing polyketides named toblerols. Relative and absolute stereochemistry were determined by NMR experiments, chemical derivatization, and the comparison of CD data between the derivatized natural product and a synthesized model compound. Biosynthetic data suggest that the cyclopropanol moiety is generated by carbon-carbon shortening of a more extended precursor. Surprisingly, a knock-out strain impaired in polyketide production showed strong inhibitory activity against other methylobacteria in contrast to the wild-type producer. The activity was inhibited by complementation with toblerols, thus suggesting that these compounds modulate an as-yet unknown methylobacterial antibiotic. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Stabilizing posture through imagery. (United States)

    Papalia, Eleonora; Manzoni, Diego; Santarcangelo, Enrica L


    Abstract In the general population, suppression of vision modulates body sway by increasing the center of pressure (CoP) velocity, while a light fingertip touch reduces the area of the CoP displacement in blindfolded subjects. This study assessed whether imagined fixation and fingertip touch differentially stabilize posture in subjects with high (highs) and low (lows) hypnotizability. Visual and tactile imageries were ineffective in lows. In highs, the effects of visual imagery could not be evaluated because the real information was ineffective; real tactile stimulation was effective only on velocity, but the imagery effects could not be definitely assessed owing to low effect size. The highs' larger variability could account for this and represents the most important finding.

  1. Stereochemistry of NaBH4 reduction of a 19-carbonyl group of 3-deoxy androgens. Synthesis of [19S-3H]- and [19R-3H]-labeled aromatase inhibitors having a 19-hydroxy group. (United States)

    Numazawa, Mitsuteru; Sohtome, Norishige; Nagaoka, Masao


    To study the stereochemical aspects of the aromatase reaction of androst-4-en-17-one (1) and its 5-ene isomer 4, competitive inhibitors of aromatase, the [19S-(3)H]- and [19R-(3)H]-labeled 19-hydroxy derivatives 2 and 5, were synthesized through NaB(3)H(4) reduction of the corresponding 19-aldehydes 3 and 6 as a key reaction. The hitherto unknown stereochemistry of the NaB(3)H(4) reduction was established based on the deuterium-labeling experiments with NaB(2)H(4). A comparison of (1)H-NMR spectra of the NaB(2)H(4) reduction products of 19-als 3 and 6 with those of the respective authentic steroids revealed that the ratios of 19S-(2)H to 19R-(2)H were 90 : 10 for the 4-ene steroid 2 and 70 : 30 for the 5-ene isomer 5, respectively. Jones oxidation of the [19S-(2)H]19-ols, followed by the non-labeled NaBH(4) reduction, gave the corresponding [19R-(2)H]19-ols 2 and 5 (R-(2)H : S-(2)H=90 : 10 for steroid 2 and 70 : 30 for steroid 5). The stereoselectively (3)H-labeled compounds 2 and 5 were similarly obtained in these sequences.

  2. Modulation of the Reactivity, Stability and Substrate- and Enantioselectivity of an Epoxidation Catalyst by Noncovalent Dynamic Attachment of a Receptor Functionality - Aspects on the Mechanism of the Jacobsen-Katsuki Epoxidation Applied to a Supramolecular System

    DEFF Research Database (Denmark)

    Jónsson, Stefán; Odille, Fabrice G. J.; Norrby, Per-Ola


    The synthesis of the components of the dynamic supramolecular hydrogen-bonded catalytic system 2 + 3 is described. The catalytic performance and substrate- and enantioselectivity of Mn(salen) catalyst 2 were investigated in the presence and absence of the Zn(porphyrin) receptor unit 3. The effects...... of pyridine and pyridine N-oxide donor ligands were also studied. Some aspects on the mechanism of the Jacobsen–Katsuki epoxidation, based on literature observations, are introduced as a means to analyse the behaviour of 2 and its modulation by the formation of macrocycle 1 with 3. A complete association...


    Directory of Open Access Journals (Sweden)

    Sunarsih Sunarsih


    Full Text Available This paper presents a model for natural syst ems used in Wastewater Treatment Plant (WWTP Sewon Bantul. The model is m odeling development, derived from the physical and biochemical phenomena involved in the biological treatment process. The numerical solution of the resulting on 13 simultaneous systems of nonlinear equations by the Quasi_Newton. Data validation is measured by facultative pond at the inlet and outlet of the pond to the concentration of b acteria, algae, zooplankton, organic matter, detritus, organic nitrogen, NH3, organi c phosphor, dissolved phosphorus, Dissolved Oxygen (DO, total coliform, faecal coliform and Biochemical Oxygen Demand (BOD. A simulation model is presented to predict performance regime steady state of domestic wastewater treatment facultative stabilization pond. The high degree of significant of at least 10% indicates that the effluent parameters can be reasonably accurately predicted.

  4. Stereochemistry of the epoxidation of bicyclo[2.2.1]hept-2-ene and its 7-syn-substituted derivatives. A DFT study

    Directory of Open Access Journals (Sweden)

    Sergiy I. Okovytyy


    Full Text Available The stereochemical aspects of epoxidation of norbornene and its 7-syn-substituted derivatives by performic acid were investigated. Geometry and thermodynamic parameters of transition states and prereactive complexes were computed at the UBHandHLYP/6-31G(d level of theory. It is shown that the transition states have a pronounced biradical character and a nearly coplanar orientation of the C=C bond and the molecule of performic acid. Transition state analysis revealed that, in the case of the syn-7-hydroxy derivative, the preference for the exo-approach of the oxidant can be explained by the stabilization of transition state with hydrogen bonding. In contrast, a chlorine atom or a methyl group at the 7-syn position facilitated the formation of endo-epoxides due to steric repulsion between the substituent and the oxidant.

  5. Photovoltaic module and module arrays

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, Jonathan [El Cerrito, CA; Graves, Simon [Berkeley, CA; Lenox, Carl J. S. [Oakland, CA; Culligan, Matthew [Berkeley, CA; Danning, Matt [Oakland, CA


    A photovoltaic (PV) module including a PV device and a frame. The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

  6. Photovoltaic module and module arrays

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, Jonathan; Graves, Simon; Lenox, Carl J. S.; Culligan, Matthew; Danning, Matt


    A photovoltaic (PV) module including a PV device and a frame, The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

  7. Reamer stabilizer

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, W.R.


    A roller reamer-stabilizer tool includes a tubular body having threaded pin and box connectors at each end adapted to be connected in a drill string and providing a fluid passage connecting the upper part of the drill string with the lower part. Rollers having integral pins at their ends are mounted in pockets in the sides of the body. The pins are received in stepped, arcuate cross-section bearing blocks received in correlative sockets in the body at the ends of the pockets. The blocks make an interference fit with the body. Releasing bar access passages allow a releasing bar to be inserted behind each block to drive, wedge, or pry it out. Means is provided to seal and lubricate the full lengths of the pin-block interfaces. The seals are downwardly facing to avoid entrapment of foreign material. The lubrication means includes a reservoir having a flexible wall exposed to pressure outside the tool. The roller pins are locked to the bearing blocks to enable the roller-block assemblies to be handled as unitary subassemblies used to replace worn out subassemblies of existing tools. The locking means at one end includes ball bearings to take axial thrust; at the other end the locking means is releasable to enable the block at that end to shift axially relating to the roller, to accommodate manufacturing tolerances and wear and prevent preloading of the thrust bearings.

  8. Laser modulator for LISA pathfinder (United States)

    Voland, C.; Lund, G.; Coppoolse, W.; Crosby, P.; Stadler, M.; Kudielka, K.; Özkan, C.


    LISA Pathfinder is an ESA experiment to demonstrate the key technologies needed for the LISA mission to detect gravitational waves in space. The LISA Pathfinder spacecraft represents one arm of the LISA interferometer, containing an optical metrology system and two proof masses as inertial references for the drag-free control system. The LISA Pathfinder payload consists of two drag-free floating test masses located in the inertial sensors with their control electronics and an optical metrology subsystem. The optical metrology subsystem monitors the movement of both test masses relative to each other and to the spacecraft with very high sensitivity and resolution. This is achieved with a heterodyne Mach- Zehnder interferometer. This interferometer requires as input two coherent laser beams with a heterodyne frequency difference of a few kHz. To generate the two laser beams with a heterodyne frequency difference a Nd:YAG laser is used together with the Laser Modulator. The Nd:YAG laser generates a single coherent laser signal at a wavelength of 1064nm which is fibre coupled to the Laser Modulator. The Laser Modulator then generates the two optical beams with the required heterodyne frequency offset. In addition, the Laser Modulator is required to perform laser amplitude stabilization and optical path difference control for the two optical signals. The Laser Modulator consists of an optical unit - the LMU - and RF synthesiser, power amplification and control electronics. These electronics are all housed in the Laser Modulator Electronics (LME). The LMU has four primary functions: • Splitting of the input laser beam into two paths for later superposition in the interferometer. • Applying different frequency shifts to each of the beams. • Providing amplitude modulation control to each of the beams. • Providing active control of the optical path length difference between the two optical paths. The present paper describes the design and performance of the LMU

  9. Modulation of the reactivity, stability and substrate- and enantioselectivity of an epoxidation catalyst by noncovalent dynamic attachment of a receptor functionality--aspects on the mechanism of the Jacobsen-Katsuki epoxidation applied to a supramolecular system. (United States)

    Jónsson, Stefán; Odille, Fabrice G J; Norrby, Per-Ola; Wärnmark, Kenneth


    The synthesis of the components of the dynamic supramolecular hydrogen-bonded catalytic system 2 + 3 is described. The catalytic performance and substrate- and enantioselectivity of Mn(salen) catalyst 2 were investigated in the presence and absence of the Zn(porphyrin) receptor unit 3. The effects of pyridine and pyridine N-oxide donor ligands were also studied. Some aspects on the mechanism of the Jacobsen-Katsuki epoxidation, based on literature observations, are introduced as a means to analyse the behaviour of 2 and its modulation by the formation of macrocycle 1 with 3. A complete association model of the metal-free system 4 + 5 refutes the earlier assumption that macrocycle 1 is the predominant form of catalyst 2 under the standard epoxidation reaction conditions with 2 + 3. Evidence are provided that receptor-binding substrates and nonbinding substrates, respectively, are epoxidised by two different catalytic species, or two distinct distributions of species in competitive epoxidations using catalytic system 2 + 3. The two species are assigned to the endo and exo faces of the Mn(salen) catalyst in macrocycle 1, and to equivalently folded oligomeric structures with monomers 2 and 3 in adjacent positions.

  10. Virtual sensors for advanced vehicle stability control

    NARCIS (Netherlands)

    Leenen, R.; Schouten, H.


    Advanced vehicle control technologies provide a great potential to further improve vehicle handling, ride and safety. The goal of this research is to demonstrate the added value of the TNO Vehicle State Estimation module to integrated active safety. State-of-the-art Electronic Stability Control

  11. MEMORY MODULATION (United States)

    Roozendaal, Benno; McGaugh, James L.


    Our memories are not all created equally strong: Some experiences are well remembered while others are remembered poorly, if at all. Research on memory modulation investigates the neurobiological processes and systems that contribute to such differences in the strength of our memories. Extensive evidence from both animal and human research indicates that emotionally significant experiences activate hormonal and brain systems that regulate the consolidation of newly acquired memories. These effects are integrated through noradrenergic activation of the basolateral amygdala which regulates memory consolidation via interactions with many other brain regions involved in consolidating memories of recent experiences. Modulatory systems not only influence neurobiological processes underlying the consolidation of new information, but also affect other mnemonic processes, including memory extinction, memory recall and working memory. In contrast to their enhancing effects on consolidation, adrenal stress hormones impair memory retrieval and working memory. Such effects, as with memory consolidation, require noradrenergic activation of the basolateral amygdala and interactions with other brain regions. PMID:22122145

  12. Coherent population trapping with polarization modulation

    CERN Document Server

    Yun, Peter; de Clercq, Emeric


    Coherent population trapping (CPT) is extensively studied for future vapor cell clocks of high frequency stability. In the constructive polarization modulation CPT scheme, a bichromatic laser field with polarization and phase synchronously modulated is applied on an atomic medium. A high contrast CPT signal is observed in this so-called double-modulation configuration, due to the fact that the atomic population does not leak to the extreme Zeeman states, and that the two CPT dark states, which are produced successively by the alternate polarizations, add constructively. Here we experimentally investigate CPT signal dynamics first in the usual configuration, a single circular polarization. The double-modulation scheme is then addressed in both cases: one pulse Rabi interaction and two pulses Ramsey interaction. The impact and the optimization of the experimental parameters involved in the time sequence are reviewed. We show that a simple sevenlevel model explains the experimental observations. The double-modul...

  13. Consensus stability testing protocols for organic photovoltaic materials and devices

    DEFF Research Database (Denmark)

    Reese, Matthew O.; Gevorgyan, Suren; Jørgensen, Mikkel


    Procedures for testing organic solar cell devices and modules with respect to stability and operational lifetime are described. The descriptions represent a consensus of the discussion and conclusions reached during the first 3 years of the international summit on OPV stability (ISOS). The proced...

  14. Dispersal and metapopulation stability

    National Research Council Canada - National Science Library

    Wang, Shaopeng; Haegeman, Bart; Loreau, Michel


    .... Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial...

  15. A novel role for the RNA-binding protein FXR1P in myoblasts cell-cycle progression by modulating p21/Cdkn1a/Cip1/Waf1 mRNA stability.

    Directory of Open Access Journals (Sweden)

    Laetitia Davidovic


    Full Text Available The Fragile X-Related 1 gene (FXR1 is a paralog of the Fragile X Mental Retardation 1 gene (FMR1, whose absence causes the Fragile X syndrome, the most common form of inherited intellectual disability. FXR1P plays an important role in normal muscle development, and its absence causes muscular abnormalities in mice, frog, and zebrafish. Seven alternatively spliced FXR1 transcripts have been identified and two of them are skeletal muscle-specific. A reduction of these isoforms is found in myoblasts from Facio-Scapulo Humeral Dystrophy (FSHD patients. FXR1P is an RNA-binding protein involved in translational control; however, so far, no mRNA target of FXR1P has been linked to the drastic muscular phenotypes caused by its absence. In this study, gene expression profiling of C2C12 myoblasts reveals that transcripts involved in cell cycle and muscular development pathways are modulated by Fxr1-depletion. We observed an increase of p21--a regulator of cell-cycle progression--in Fxr1-knocked-down mouse C2C12 and FSHD human myoblasts. Rescue of this molecular phenotype is possible by re-expressing human FXR1P in Fxr1-depleted C2C12 cells. FXR1P muscle-specific isoforms bind p21 mRNA via direct interaction with a conserved G-quadruplex located in its 3' untranslated region. The FXR1P/G-quadruplex complex reduces the half-life of p21 mRNA. In the absence of FXR1P, the upregulation of p21 mRNA determines the elevated level of its protein product that affects cell-cycle progression inducing a premature cell-cycle exit and generating a pool of cells blocked at G0. Our study describes a novel role of FXR1P that has crucial implications for the understanding of its role during myogenesis and muscle development, since we show here that in its absence a reduced number of myoblasts will be available for muscle formation/regeneration, shedding new light into the pathophysiology of FSHD.

  16. Plutonium inventories for stabilization and stabilized materials

    Energy Technology Data Exchange (ETDEWEB)

    Williams, A.K.


    The objective of the breakout session was to identify characteristics of materials containing plutonium, the need to stabilize these materials for storage, and plans to accomplish the stabilization activities. All current stabilization activities are driven by the Defense Nuclear Facilities Safety Board Recommendation 94-1 (May 26, 1994) and by the recently completed Plutonium ES&H Vulnerability Assessment (DOE-EH-0415). The Implementation Plan for accomplishing stabilization of plutonium-bearing residues in response to the Recommendation and the Assessment was published by DOE on February 28, 1995. This Implementation Plan (IP) commits to stabilizing problem materials within 3 years, and stabilizing all other materials within 8 years. The IP identifies approximately 20 metric tons of plutonium requiring stabilization and/or repackaging. A further breakdown shows this material to consist of 8.5 metric tons of plutonium metal and alloys, 5.5 metric tons of plutonium as oxide, and 6 metric tons of plutonium as residues. Stabilization of the metal and oxide categories containing greater than 50 weight percent plutonium is covered by DOE Standard {open_quotes}Criteria for Safe Storage of Plutonium Metals and Oxides{close_quotes} December, 1994 (DOE-STD-3013-94). This standard establishes criteria for safe storage of stabilized plutonium metals and oxides for up to 50 years. Each of the DOE sites and contractors with large plutonium inventories has either started or is preparing to start stabilization activities to meet these criteria.

  17. Module theory, extending modules and generalizations

    CERN Document Server

    Tercan, Adnan


    The main focus of this monograph is to offer a comprehensive presentation of known and new results on various generalizations of CS-modules and CS-rings. Extending (or CS) modules are generalizations of injective (and also semisimple or uniform) modules. While the theory of CS-modules is well documented in monographs and textbooks, results on generalized forms of the CS property as well as dual notions are far less present in the literature. With their work the authors provide a solid background to module theory, accessible to anyone familiar with basic abstract algebra. The focus of the book is on direct sums of CS-modules and classes of modules related to CS-modules, such as relative (injective) ejective modules, (quasi) continuous modules, and lifting modules. In particular, matrix CS-rings are studied and clear proofs of fundamental decomposition results on CS-modules over commutative domains are given, thus complementing existing monographs in this area. Open problems round out the work and establish the...

  18. Identification of unstable network modules reveals disease modules associated with the progression of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Masataka Kikuchi

    Full Text Available Alzheimer's disease (AD, the most common cause of dementia, is associated with aging, and it leads to neuron death. Deposits of amyloid β and aberrantly phosphorylated tau protein are known as pathological hallmarks of AD, but the underlying mechanisms have not yet been revealed. A high-throughput gene expression analysis previously showed that differentially expressed genes accompanying the progression of AD were more down-regulated than up-regulated in the later stages of AD. This suggested that the molecular networks and their constituent modules collapsed along with AD progression. In this study, by using gene expression profiles and protein interaction networks (PINs, we identified the PINs expressed in three brain regions: the entorhinal cortex (EC, hippocampus (HIP and superior frontal gyrus (SFG. Dividing the expressed PINs into modules, we examined the stability of the modules with AD progression and with normal aging. We found that in the AD modules, the constituent proteins, interactions and cellular functions were not maintained between consecutive stages through all brain regions. Interestingly, the modules were collapsed with AD progression, specifically in the EC region. By identifying the modules that were affected by AD pathology, we found the transcriptional regulation-associated modules that interact with the proteasome-associated module via UCHL5 hub protein, which is a deubiquitinating enzyme. Considering PINs as a system made of network modules, we found that the modules relevant to the transcriptional regulation are disrupted in the EC region, which affects the ubiquitin-proteasome system.

  19. CLIC Quadrupole Module final report

    CERN Document Server

    Artoos, K; Mainaud-Durand, H


    Future Linear colliders will need particle beam sizes in the nanometre range. The beam also needs to be stable all along the beam line. The CLIC Main Beam Quadrupole (MBQ) module has been defined and studied. It is meant as a test stand for stabilisation and pre-alignment with a MB Quadrupole. The main topic that has been tackled concerns the Quadrupole magnet stabilisation to 1nm at 1Hz. This is needed to obtain the desired CLIC luminosity of 2.1034 cm-2m-1. The deliverable was demonstrated by procuring a MBQ and by stabilising a powered and cooled CLIC MBQ quadrupole. In addition, the stabilisation system has to be compatible with the pre-alignment procedures. Pre-alignment movement resolution has been demonstrated to 1m. The last step is the combined test of stability with a quadrupole on a CLIC Module with the pre-alignment.

  20. Ballasted photovoltaic module and module arrays (United States)

    Botkin, Jonathan [El Cerrito, CA; Graves, Simon [Berkeley, CA; Danning, Matt [Oakland, CA


    A photovoltaic (PV) module assembly including a PV module and a ballast tray. The PV module includes a PV device and a frame. A PV laminate is assembled to the frame, and the frame includes an arm. The ballast tray is adapted for containing ballast and is removably associated with the PV module in a ballasting state where the tray is vertically under the PV laminate and vertically over the arm to impede overt displacement of the PV module. The PV module assembly can be installed to a flat commercial rooftop, with the PV module and the ballast tray both resting upon the rooftop. In some embodiments, the ballasting state includes corresponding surfaces of the arm and the tray being spaced from one another under normal (low or no wind) conditions, such that the frame is not continuously subjected to a weight of the tray.

  1. On the stabilizing mechanism of 2D absolute and global instabilities by 3D streaks


    Cossu, Carlo


    Global and local absolute instabilities of 2D wakes are known to be stabilized by spanwise periodic modulations of the wake profile. The present study shows that this stabilizing effect is of general nature and can be mimicked by enforcing spanwise periodic modulations of the wave advection velocity in the generalized complex Ginzburg-Landau equation. The first order sensitivity of the absolute and global growth rate to the enforced modulation is zero, exactly as in the Navier-Stokes case. We...

  2. Robust measurement of thin-film photovoltaic modules exhibiting light-induced transients (United States)

    Deceglie, Michael G.; Silverman, Timothy J.; Marion, Bill; Kurtz, Sarah R.


    Light-induced changes to the current-voltage characteristic of thin-film photovoltaic modules (i.e. light-soaking effects) frustrate the repeatable measurement of their operating power. We describe best practices for mitigating, or stabilizing, light-soaking effects for both CdTe and CIGS modules to enable robust, repeatable, and relevant power measurements. We motivate the practices by detailing how modules react to changes in different stabilization methods. We also describe and demonstrate a method for validating alternative stabilization procedures, such as those relying on forward bias in the dark. Reliable measurements of module power are critical for qualification testing, reliability testing, and power rating.

  3. Robust Measurement of Thin-Film Photovoltaic Modules Exhibiting Light-Induced Transients: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Deceglie, Michael, G.; Silverman, Timothy J.; Marion, Bill; Kurtz, Sarah R.


    Light-induced changes to the current-voltage characteristic of thin-film photovoltaic modules (i.e. light-soaking effects) frustrate the repeatable measurement of their operating power. We describe best practices for mitigating, or stabilizing, light-soaking effects for both CdTe and CIGS modules to enable robust, repeatable, and relevant power measurements. We motivate the practices by detailing how modules react to changes in different stabilization methods. We also describe and demonstrate a method for validating alternative stabilization procedures, such as those relying on forward bias in the dark. Reliable measurements of module power are critical for qualification testing, reliability testing, and power rating.

  4. Stereochemistry of organometallic and inorganic compounds

    CERN Document Server


    The authors of this fourth volume in the series have reviewed the making and breaking of chemical bonds in a sophisticated manner. In particular, new pressures brought about by environmental concerns, larger demands for the medical and pharmaceutical sectors and economics of the market place are forcing us into demanding greater stereochemical control and better product yields for chemical reactions capable of producing useful products. The chapters are written by leading experts in this area and give excellent overviews of the strengths and weaknesses of the various methodologies.In C

  5. Determination of the stereochemistry of 4-chromenecarbaldehydes ...

    African Journals Online (AJOL)

    The paper reports studies on the use of 4-chromenecarbaldehydes as suitable substrates for the assessment of the accuracy of interpretations of Nuclear Overhauser Enhancements (NOE) data for chromenecarbaldehydes and related compounds, such as the 3,4-dibromochromanones. The investigative protocol that has ...

  6. Performance of Skutterudite-Based Modules (United States)

    Nie, G.; Suzuki, S.; Tomida, T.; Sumiyoshi, A.; Ochi, T.; Mukaiyama, K.; Kikuchi, M.; Guo, J. Q.; Yamamoto, A.; Obara, H.


    Due to their excellent thermoelectric (TE) performance, skutterudite materials have been selected by many laboratories and companies for development of TE modules to recover power from waste heat at high temperatures (300°C to 600°C). After years of effort, we have developed reliable n- and p-type skutterudite materials showing maximum figure of merit ( ZT) of 1.0 at 550°C and 0.75 at 450°C, respectively. In this work, we systematically investigated the performance of a module made using these two kinds of skutterudite. We demonstrate ˜7.2% conversion efficiency for temperature of 600°C at the hot side of the module and 50°C at the cold side, and show that the module had excellent stability in the high-temperature environment. Further improving the TE performance of our skutterudites, the conversion efficiency reached ˜8.5% under the same condition.

  7. Actively stabilized silicon microrings with integrated surface-state-absorption photodetectors using a slope-detection method. (United States)

    Li, Yu; Poon, Andrew W


    We propose and experimentally demonstrate actively stabilized silicon microrings with integrated surface-state-absorption (SSA) photodetectors using a slope-detection method. Our proof-of-concept experiments reveal that the active stabilization using multiple discrete-step slope thresholds can effectively reduce the microring transmitted intensity variations upon various temperature modulation conditions. We demonstrate an actively stabilized microring transmission with intensity modulations within ~2.5 dB upon a 5mHz temperature modulation between 17 °C and 31 °C, which is ~7.5dB improved from without stabilization. The active alignment tolerance between the stabilized microring resonance wavelength and a carrier wavelength is ~0.16 nm over a 14°C temperature modulation. We observe open eye-diagrams at a data transmission rate of up to 30 Gb/s under temperature modulations with actively stabilized silicon microrings.

  8. Dynamic stabilization of Rayleigh-Taylor instability in ablation fronts

    Directory of Open Access Journals (Sweden)

    Piriz A.R.


    Full Text Available Dynamic stabilization of Rayleigh-Taylor instability in an ablation front is studied by considering the simplest possible modulations in the acceleration. Explicit analytical expressions for the instability growth rate and for the boundaries of the stability region are obtained by considering a sequence of Dirac deltas. Besides, general square waves allow for studying the effect of the driving asymmetries on the stability region as well as the optimization process. The essential role of compressibility is phenomenologically addressed in order to find the constraints it imposes on the stability region.

  9. Stability of parallel flows

    CERN Document Server

    Betchov, R


    Stability of Parallel Flows provides information pertinent to hydrodynamical stability. This book explores the stability problems that occur in various fields, including electronics, mechanics, oceanography, administration, economics, as well as naval and aeronautical engineering. Organized into two parts encompassing 10 chapters, this book starts with an overview of the general equations of a two-dimensional incompressible flow. This text then explores the stability of a laminar boundary layer and presents the equation of the inviscid approximation. Other chapters present the general equation

  10. Precision displacement measurement using a modulating ESPI (United States)

    Kim, Seong Jong; Kang, Young June; Hong, Dong Pyo; Kim, Kyung Suk; Park, Nak Kyu; Ryu, Weon Jae; Choi, Man Young


    Laser interferometry is widely used as a measuring system in many fields because of its high resolution and ability to measure a broad area in real-time all at once. In conventional LASER interferometry, for example Out-of-plane ESPI(Electronic Speckle Pattern Interferometry), In plane ESPI, Shearography and Holography, it uses PZT or other components as a phase shift instrumentation to extract 3D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include non-linear errors and limited time of use. In the present study, a new type of LASER interferometry using a laser diode is proposed. Using LASER Diode Sinusoidal Phase Modulating (LD-SPM) interferometry, the phase modulation can directly modulated by controlling the LASER Diode injection current thereby eliminating the need for PZT and its components. This makes the interferometry more compact. This paper reports on a new approach to the LD Modulating interferometry that involves four-bucket phase shift method. This study proposes a four-bucket phase mapping algorithm, which developed to have a guaranteed application, to stabilize the system in the field and to be a user-friendly GUI. In this paper, LD modulating interferometry had shown the theory for LD wavelength modulation and sinusoidal phase modulation. Four-bucket phase mapping algorithm then introduced.

  11. Limits to Stability (United States)

    Cottey, Alan


    The author reflects briefly on what limited degree of global ecological stability and human cultural stability may be achieved, provided that humanity retains hope and does not give way to despair or hide in denial. These thoughts were triggered by a recent conference on International Stability and Systems Engineering. (Contains 5 notes.)

  12. Fractional Stability of Trunk Acceleration Dynamics of Daily-Life Walking: Toward a Unified Concept of Gait Stability. (United States)

    Ihlen, Espen A F; van Schooten, Kimberley S; Bruijn, Sjoerd M; Pijnappels, Mirjam; van Dieën, Jaap H


    Over the last decades, various measures have been introduced to assess stability during walking. All of these measures assume that gait stability may be equated with exponential stability, where dynamic stability is quantified by a Floquet multiplier or Lyapunov exponent. These specific constructs of dynamic stability assume that the gait dynamics are time independent and without phase transitions. In this case the temporal change in distance, d ( t ), between neighboring trajectories in state space is assumed to be an exponential function of time. However, results from walking models and empirical studies show that the assumptions of exponential stability break down in the vicinity of phase transitions that are present in each step cycle. Here we apply a general non-exponential construct of gait stability, called fractional stability, which can define dynamic stability in the presence of phase transitions. Fractional stability employs the fractional indices, α and β, of differential operator which allow modeling of singularities in d ( t ) that cannot be captured by exponential stability. The fractional stability provided an improved fit of d ( t ) compared to exponential stability when applied to trunk accelerations during daily-life walking in community-dwelling older adults. Moreover, using multivariate empirical mode decomposition surrogates, we found that the singularities in d ( t ), which were well modeled by fractional stability, are created by phase-dependent modulation of gait. The new construct of fractional stability may represent a physiologically more valid concept of stability in vicinity of phase transitions and may thus pave the way for a more unified concept of gait stability.

  13. Fractional Stability of Trunk Acceleration Dynamics of Daily-Life Walking: Toward a Unified Concept of Gait Stability

    Directory of Open Access Journals (Sweden)

    Espen A. F. Ihlen


    Full Text Available Over the last decades, various measures have been introduced to assess stability during walking. All of these measures assume that gait stability may be equated with exponential stability, where dynamic stability is quantified by a Floquet multiplier or Lyapunov exponent. These specific constructs of dynamic stability assume that the gait dynamics are time independent and without phase transitions. In this case the temporal change in distance, d(t, between neighboring trajectories in state space is assumed to be an exponential function of time. However, results from walking models and empirical studies show that the assumptions of exponential stability break down in the vicinity of phase transitions that are present in each step cycle. Here we apply a general non-exponential construct of gait stability, called fractional stability, which can define dynamic stability in the presence of phase transitions. Fractional stability employs the fractional indices, α and β, of differential operator which allow modeling of singularities in d(t that cannot be captured by exponential stability. The fractional stability provided an improved fit of d(t compared to exponential stability when applied to trunk accelerations during daily-life walking in community-dwelling older adults. Moreover, using multivariate empirical mode decomposition surrogates, we found that the singularities in d(t, which were well modeled by fractional stability, are created by phase-dependent modulation of gait. The new construct of fractional stability may represent a physiologically more valid concept of stability in vicinity of phase transitions and may thus pave the way for a more unified concept of gait stability.

  14. Feedback stabilization initiative

    Energy Technology Data Exchange (ETDEWEB)



    Much progress has been made in attaining high confinement regimes in magnetic confinement devices. These operating modes tend to be transient, however, due to the onset of MHD instabilities, and their stabilization is critical for improved performance at steady state. This report describes the Feedback Stabilization Initiative (FSI), a broad-based, multi-institutional effort to develop and implement methods for raising the achievable plasma betas through active MHD feedback stabilization. A key element in this proposed effort is the Feedback Stabilization Experiment (FSX), a medium-sized, national facility that would be specifically dedicated to demonstrating beta improvement in reactor relevant plasmas by using a variety of MHD feedback stabilization schemes.

  15. Stability and Diversity of Ecosystems

    National Research Council Canada - National Science Library

    Anthony R. Ives; Stephen R. Carpenter


    .... The relationship is also complex, because the concept of stability is multifaceted; different types of stability describing different properties of ecosystems lead to multiple diversity-stability relationships...

  16. Electroabsorption optical modulator

    Energy Technology Data Exchange (ETDEWEB)

    Skogen, Erik J.


    An electroabsorption modulator incorporates waveguiding regions along the length of the modulator that include quantum wells where at least two of the regions have quantum wells with different bandgaps. In one embodiment of the invention, the regions are arranged such that the quantum wells have bandgaps with decreasing bandgap energy along the length of the modulator from the modulator's input to its output. The bandgap energy of the quantum wells may be decreased in discrete steps or continuously. Advantageously, such an arrangement better distributes the optical absorption as well as the carrier density along the length of the modulator. Further advantageously, the modulator may handle increased optical power as compared with prior art modulators of similar dimensions, which allows for improved link gain when the optical modulator is used in an analog optical communication link.

  17. CDC 7600 module slice

    CERN Multimedia

    Each module contained 8 circuit cards for a total of about 300-500 uncovered transistors packaged with face plates so the Freon plates wouldn't touch the circuits. (cooling plates that surrounded each module).

  18. Reduced multiplication modules

    Indian Academy of Sciences (India)

    for some ideal of . As defined for a commutative ring , an -module is said to be reduced if the intersection of prime submodules of is zero. The prime spectrum and minimal prime submodules of the reduced module are studied.

  19. CDC 6600 Cordwood Module

    CERN Document Server


    The CDC 6600 cordwood module containing 64 silicon transistors. The module was mounted between two plates that were cooled conductive by a refrigeration unit via the front panel. The construction of this module uses the cord method, so called because the resistors seem to be stacked like cord between the two circuit boards in order to obtain a high density. The 6600 model contained nearly 6,000 such modules.

  20. Polarization modulators for CMBPol

    Energy Technology Data Exchange (ETDEWEB)

    Ade, P A R; Savini, G [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom); Chuss, D T [NASA Goddard Space Flight Center, Code 665, Greenbelt, MD, 20771 (United States); Hanany, S [School of Physics and Astronomy, University of Minnesota/Twin Cities, Minneapolis, MN, 55455 (United States); Haynes, V; Pisano, G [University of Manchester, School of Physics and Astronomy - Alan Turing Building, Upper Brooke street, Manchester, M13 4PL (United Kingdom); Keating, B G [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0424 (United States); Kogut, A [Code 665 Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ruhl, J E [Physics Department, Case Western Reserve University, Cleveland, OH, 44106 (United States); Wollack, E J [Observational Cosmology Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)


    We review a number of technologies that are candidates for active polarization modulators for CMBPol. The technologies are appropriate for instruments that use bolometric detectors and include birefringent crystal-based and metal-mesh-based half-wave plates, variable phase polarization modulator, Faraday rotator, and photolithographed modulators. We also give a current account of the status of millimeter-wave orthomode transducers.

  1. Reduced multiplication modules

    Indian Academy of Sciences (India)

    [16] Smith P F and Tercan A, Generalizations of CS-modules, Commun. Algebra 21 (1993). 1809–1847. [17] Yucel T and Mustafa A, Prime modules and submodules, Commun. Algebra 31(11). (2003) 5253–5261. [18] Zhang G, Wang F and Tong W, Multiplication modules in which every prime submodule is contained in a ...

  2. Modulating lignin in plants (United States)

    Apuya, Nestor; Bobzin, Steven Craig; Okamuro, Jack; Zhang, Ke


    Materials and methods for modulating (e.g., increasing or decreasing) lignin content in plants are disclosed. For example, nucleic acids encoding lignin-modulating polypeptides are disclosed as well as methods for using such nucleic acids to generate transgenic plants having a modulated lignin content.

  3. Stability for closed surfaces in a background space

    DEFF Research Database (Denmark)

    Cohen, Ralph L. Cohen; Madsen, Ib Henning


    In this paper we present a new proof of the homological stability of the moduli space of closed surfaces in a simply connected background space K , which we denote by S g (K) . The homology stability of surfaces in K with an arbitrary number of boundary components, S g,n (K) , was studied...... by the authors in a previous paper. The study there relied on stability results for the homology of mapping class groups, Γ g,n with certain families of twisted coefficients. It turns out that these mapping class groups only have homological stability when n , the number of boundary components, is positive......, or in the closed case when the coefficient modules are trivial. Because of this we present a new proof of the rational homological stability for S g (K) , that is homotopy theoretic in nature. We also take the opportunity to prove a new stability theorem for closed surfaces in K that have marked points....

  4. Reconstructions in ultrasound modulated optical tomography

    KAUST Repository

    Allmaras, Moritz


    We introduce a mathematical model for ultrasound modulated optical tomography and present a simple reconstruction scheme for recovering the spatially varying optical absorption coefficient from scanning measurements with narrowly focused ultrasound signals. Computational results for this model show that the reconstruction of sharp features of the absorption coefficient is possible. A formal linearization of the model leads to an equation with a Fredholm operator, which explains the stability observed in our numerical experiments. © de Gruyter 2011.

  5. Coherent population trapping with polarization modulation

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Peter, E-mail:; Guérandel, Stéphane; Clercq, Emeric de [LNE-SYRTE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, 61 avenue de l' Observatoire, 75014 Paris (France)


    Coherent population trapping (CPT) is extensively studied for future vapor cell clocks of high frequency stability. In the constructive polarization modulation CPT scheme, a bichromatic laser field with polarization and phase synchronously modulated is applied on an atomic medium. A high contrast CPT signal is observed in this so-called double-modulation configuration, due to the fact that the atomic population does not leak to the extreme Zeeman states, and that the two CPT dark states, which are produced successively by the alternate polarizations, add constructively. Here, we experimentally investigate CPT signal dynamics first in the usual configuration, a single circular polarization. The double-modulation scheme is then addressed in both cases: one pulse Rabi interaction and two pulses Ramsey interaction. The impact and the optimization of the experimental parameters involved in the time sequence are reviewed. We show that a simple seven-level model explains the experimental observations. The double-modulation scheme yields a high contrast similar to the one of other high contrast configurations like push-pull optical pumping or crossed linear polarization scheme, with a setup allowing a higher compactness. The constructive polarization modulation is attractive for atomic clock, atomic magnetometer, and high precision spectroscopy applications.

  6. Divisible ℤ-modules

    Directory of Open Access Journals (Sweden)

    Futa Yuichi


    Full Text Available In this article, we formalize the definition of divisible ℤ-module and its properties in the Mizar system [3]. We formally prove that any non-trivial divisible ℤ-modules are not finitely-generated.We introduce a divisible ℤ-module, equivalent to a vector space of a torsion-free ℤ-module with a coefficient ring ℚ. ℤ-modules are important for lattice problems, LLL (Lenstra, Lenstra and Lovász base reduction algorithm [15], cryptographic systems with lattices [16] and coding theory [8].

  7. Internet Addiction: Stability and Change (United States)

    Huang, Chiungjung


    This longitudinal study examined five indices of stability and change in Internet addiction: structural stability, mean-level stability, differential stability, individual-level stability, and ipsative stability. The study sample was 351 undergraduate students from end of freshman year to end of junior year. Convergent findings revealed stability…

  8. Artist Photovoltaic Modules

    Directory of Open Access Journals (Sweden)

    Shui-Yang Lien


    Full Text Available In this paper, a full-color photovoltaic (PV module, called the artist PV module, is developed by laser processes. A full-color image source is printed on the back of a protective glass using an inkjet printer, and a brightened grayscale mask is used to precisely define regions on the module where colors need to be revealed. Artist PV modules with 1.1 × 1.4 m2 area have high a retaining power output of 139 W and an aesthetic appearance making them more competitive than other building-integrated photovoltaic (BIPV products. Furthermore, the installation of artist PV modules as curtain walls without metal frames is also demonstrated. This type of installation offers an aesthetic advantage by introducing supporting fittings, originating from the field of glass technology. Hence, this paper is expected to elevate BIPV modules to an art form and generate research interests in developing more functional PV modules.

  9. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni......This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  10. Ornithopter flight stabilization (United States)

    Dietl, John M.; Garcia, Ephrahim


    The quasi-steady aerodynamics model and the vehicle dynamics model of ornithopter flight are explained, and numerical methods are described to capture limit cycle behavior in ornithopter flight. The Floquet method is used to determine stability in forward flight, and a linear discrete-time state-space model is developed. This is used to calculate stabilizing and disturbance-rejecting controllers.

  11. Stability of Hyperthermophilic Proteins

    DEFF Research Database (Denmark)

    Stiefler-Jensen, Daniel

    in the high stability of hyperthermophilic enzymes. The thesis starts with an introduction to the field of protein and enzyme stability with special focus on the thermophilic and hyperthermophilic enzymes and proteins. After the introduction three original research manuscripts present the experimental data...

  12. Conformational stability of calreticulin

    DEFF Research Database (Denmark)

    Jørgensen, Charlotte S; Trandum, Christa; Larsen, Nanna Brink


    The conformational stability of calreticulin was investigated. Apparent unfolding temperatures (Tm) increased from 31 degrees C at pH 5 to 51 degrees C at pH 9, but electrophoretic analysis revealed that calreticulin oligomerized instead of unfolding. Structural analyses showed that the single C......-terminal alpha-helix was of major importance to the conformational stability of calreticulin....

  13. Conformational stability of calreticulin

    DEFF Research Database (Denmark)

    Jørgensen, C.S.; Trandum, C.; Larsen, N.


    The conformational stability of calreticulin was investigated. Apparent unfolding temperatures (T-m) increased from 31 degrees C at pH 5 to 51 degrees C at pH 9, but electrophoretic analysis revealed that calreticulin oligomerized instead of unfolding. Structural analyses showed that the single C......-terminal a-helix was of major importance to the conformational stability of calreticulin....

  14. The statistical stability phenomenon

    CERN Document Server

    Gorban, Igor I


    This monograph investigates violations of statistical stability of physical events, variables, and processes and develops a new physical-mathematical theory taking into consideration such violations – the theory of hyper-random phenomena. There are five parts. The first describes the phenomenon of statistical stability and its features, and develops methods for detecting violations of statistical stability, in particular when data is limited. The second part presents several examples of real processes of different physical nature and demonstrates the violation of statistical stability over broad observation intervals. The third part outlines the mathematical foundations of the theory of hyper-random phenomena, while the fourth develops the foundations of the mathematical analysis of divergent and many-valued functions. The fifth part contains theoretical and experimental studies of statistical laws where there is violation of statistical stability. The monograph should be of particular interest to engineers...

  15. Stochastic Dynamics Underlying Cognitive Stability and Flexibility.

    Directory of Open Access Journals (Sweden)

    Kai Ueltzhöffer


    Full Text Available Cognitive stability and flexibility are core functions in the successful pursuit of behavioral goals. While there is evidence for a common frontoparietal network underlying both functions and for a key role of dopamine in the modulation of flexible versus stable behavior, the exact neurocomputational mechanisms underlying those executive functions and their adaptation to environmental demands are still unclear. In this work we study the neurocomputational mechanisms underlying cue based task switching (flexibility and distractor inhibition (stability in a paradigm specifically designed to probe both functions. We develop a physiologically plausible, explicit model of neural networks that maintain the currently active task rule in working memory and implement the decision process. We simplify the four-choice decision network to a nonlinear drift-diffusion process that we canonically derive from a generic winner-take-all network model. By fitting our model to the behavioral data of individual subjects, we can reproduce their full behavior in terms of decisions and reaction time distributions in baseline as well as distractor inhibition and switch conditions. Furthermore, we predict the individual hemodynamic response timecourse of the rule-representing network and localize it to a frontoparietal network including the inferior frontal junction area and the intraparietal sulcus, using functional magnetic resonance imaging. This refines the understanding of task-switch-related frontoparietal brain activity as reflecting attractor-like working memory representations of task rules. Finally, we estimate the subject-specific stability of the rule-representing attractor states in terms of the minimal action associated with a transition between different rule states in the phase-space of the fitted models. This stability measure correlates with switching-specific thalamocorticostriatal activation, i.e., with a system associated with flexible working memory

  16. The role of stabilization centers in protein thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Magyar, Csaba [Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt 2, H-1117 Budapest (Hungary); Gromiha, M. Michael [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036 (India); Sávoly, Zoltán [Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt 2, H-1117 Budapest (Hungary); Simon, István, E-mail: [Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt 2, H-1117 Budapest (Hungary)


    The definition of stabilization centers was introduced almost two decades ago. They are centers of noncovalent long range interaction clusters, believed to have a role in maintaining the three-dimensional structure of proteins by preventing their decay due to their cooperative long range interactions. Here, this hypothesis is investigated from the viewpoint of thermal stability for the first time, using a large protein thermodynamics database. The positions of amino acids belonging to stabilization centers are correlated with available experimental thermodynamic data on protein thermal stability. Our analysis suggests that stabilization centers, especially solvent exposed ones, do contribute to the thermal stabilization of proteins. - Highlights: • Stabilization centers contribute to thermal stabilization of protein structures. • Stabilization center content correlates with melting temperature of proteins. • Exposed stabilization center content correlates with stability even in hyperthermophiles. • Stability changing mutations are frequently found at stabilization centers.

  17. An active interferometer-stabilization scheme with linear phase control

    DEFF Research Database (Denmark)

    Vardhan Krishnamachari, Vishnu; Andresen, Esben Ravn; Potma, Eric Olaf


    We report a simple and robust computer-based active interferometer stabilization scheme which does not require modulation of the interfering beams and relies on an error signal which is linearly related to the optical path difference. In this setup, a non-collinearly propagating reference laser b...... beam stabilizes the interference output of the laser light propagating collinearly through the interferometer. This stabilization scheme enables adjustable phase control with 20 ms switching times in the range from 0.02π radians to 6π radians at 632.8 nm....

  18. Research on Design of MUH Attitude Stability Augmentation Control System (United States)

    Fan, Shigang


    Attitude stability augmentation control system with a lower cost need to be designed so that MUH (Mini Unmanned Helicopter) can adapt to different types of geographic environment and fly steadily although the weather may be bad. Attitude feedback was calculated mainly by filtering estimation within attitude acquisition module in this system. Stability augmentation can be improved mainly by PI. This paper will depict running principle and designing process of MUH attitude stability augmentation control system and algorithm that is considered as an important part in this system.

  19. Delphi Accounts Receivable Module - (United States)

    Department of Transportation — Delphi accounts receivable module contains the following data elements, but are not limited to customer information, cash receipts, line of accounting details, bill...

  20. Modulation cancellation method (MOCAM) in modulation spectroscopy (United States)

    Spagnolo, V.; Dong, L.; Kosterev, A. A.; Thomazy, D.; Doty, J. H.; Tittel, F. K.


    An innovative spectroscopic technique based on balancing and cancellation of modulated signals induced by two excitation sources. We used quartz enhanced photoacoustic spectroscopy (QEPAS) in a 2f wavelength modulation mode as an absorption sensing technique and employed a modulation cancelation approach for spectroscopic measurements of small temperature differences in a gas mixture and detection of broadband absorbers. We demonstrated measurement of small temperature differences in a C2H2/N2gas mixture with a sensitivity of 30 mK in 17 sec and detection of hydrazine, a broadband absorbing chemical species, down to concentration of 1 part per million in volume in 1 sec. In both cases we used near-infrared laser diodes and selected overtone transitions.nuscrip

  1. Flexible packaging for PV modules (United States)

    Dhere, Neelkanth G.


    Economic, flexible packages that provide needed level of protection to organic and some other PV cells over >25-years have not yet been developed. However, flexible packaging is essential in niche large-scale applications. Typical configuration used in flexible photovoltaic (PV) module packaging is transparent frontsheet/encapsulant/PV cells/flexible substrate. Besides flexibility of various components, the solder bonds should also be flexible and resistant to fatigue due to cyclic loading. Flexible front sheets should provide optical transparency, mechanical protection, scratch resistance, dielectric isolation, water resistance, UV stability and adhesion to encapsulant. Examples are Tefzel, Tedlar and Silicone. Dirt can get embedded in soft layers such as silicone and obscure light. Water vapor transmittance rate (WVTR) of polymer films used in the food packaging industry as moisture barriers are ~0.05 g/( under ambient conditions. In comparison, light emitting diodes employ packaging components that have WVTR of ~10-6 g/( WVTR of polymer sheets can be improved by coating them with dense inorganic/organic multilayers. Ethylene vinyl acetate, an amorphous copolymer used predominantly by the PV industry has very high O2 and H2O diffusivity. Quaternary carbon chains (such as acetate) in a polymer lead to cleavage and loss of adhesional strength at relatively low exposures. Reactivity of PV module components increases in presence of O2 and H2O. Adhesional strength degrades due to the breakdown of structure of polymer by reactive, free radicals formed by high-energy radiation. Free radical formation in polymers is reduced when the aromatic rings are attached at regular intervals. This paper will review flexible packaging for PV modules.

  2. Dispersal and metapopulation stability

    Directory of Open Access Journals (Sweden)

    Shaopeng Wang


    Full Text Available Metapopulation dynamics are jointly regulated by local and spatial factors. These factors may affect the dynamics of local populations and of the entire metapopulation differently. Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial. Here we present a simple metapopulation model to study how dispersal, in interaction with other spatial and local processes, affects the temporal variability of metapopulations in a stochastic environment. Our results show that in homogeneous metapopulations, the local stabilizing and spatial synchronizing effects of dispersal cancel each other out, such that dispersal has no effect on metapopulation variability. This result is robust to moderate heterogeneities in local and spatial parameters. When local and spatial dynamics exhibit high heterogeneities, however, dispersal can either stabilize or destabilize metapopulation dynamics through various mechanisms. Our findings have important theoretical and practical implications. We show that dispersal functions as a form of spatial intraspecific mutualism in metapopulation dynamics and that its effect on metapopulation stability is opposite to that of interspecific competition on local community stability. Our results also suggest that conservation corridors should be designed with appreciation of spatial heterogeneities in population dynamics in order to maximize metapopulation stability.

  3. Linking stoichiometric homoeostasis with ecosystem structure, functioning and stability. (United States)

    Yu, Qiang; Chen, Quansheng; Elser, James J; He, Nianpeng; Wu, Honghui; Zhang, Guangming; Wu, Jianguo; Bai, Yongfei; Han, Xingguo


    Ecosystem structure, functioning and stability have been a focus of ecological and environmental sciences during the past two decades. The mechanisms underlying their relationship, however, are not well understood. Based on comprehensive studies in Inner Mongolia grassland, here we show that species-level stoichiometric homoeostasis was consistently positively correlated with dominance and stability on both 2-year and 27-year temporal scales and across a 1200-km spatial transect. At the community level, stoichiometric homoeostasis was also positively correlated with ecosystem function and stability in most cases. Thus, homoeostatic species tend to have high and stable biomass; and ecosystems dominated by more homoeostatic species have higher productivity and greater stability. By modulating organism responses to key environmental drivers, stoichiometric homoeostasis appears to be a major mechanism responsible for the structure, functioning and stability of grassland ecosystems. © 2010 Blackwell Publishing Ltd/CNRS.

  4. Gravity stabilizes itself

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Sumanta; SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)


    We show that a possible resolution to the stabilization of an extra spatial dimension (radion) can be obtained solely in the context of gravitational dynamics itself without the necessity of introducing any external stabilizing field. In this scenario the stabilized value of the radion field gets determined in terms of the parameters appearing in the higher curvature gravitational action. Furthermore, the mass of the radion field and its coupling to the standard model fields are found to be in the weak scale implying possible signatures in the TeV scale colliders. Some resulting implications are also discussed. (orig.)

  5. Modeling of residue stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Velasco-Arjona, A.; Castro, M.D.L. de [Univ. of Cordoba (Spain). Dept. of Analytical Chemistry; Izquierdo, A. [Gemasur, Cordoba (Spain). Dept. of R and D


    Because of the variety in anthropogenic toxic residues produced by human activity, the establishment of a general procedure for the destruction of these residues or transformation into less toxic materials is difficult. A study was made on the decrease in toxicity of various contaminated residues when treated with three different stabilizers. General criteria of the requirements for stabilization were also established, which depended on both the toxicity and nature of the toxic substances. The modeling of the stabilization process will allow nonspecialized personnel to carry out the operations and will also standardize the modus operandi of such enterprises.

  6. Stability analysis of ferrofluids

    Directory of Open Access Journals (Sweden)

    Katharina Duda


    Full Text Available Superparamagnetic iron oxides (SPIOs are used as tracer for the new imaging technique Magnetic Particle Imaging. The stability of ferrofluids for medical application has a great importance, in addition to the particle size. The shell material, which protects the iron core prior from agglomeration and sedimentation, can be degraded by various processes. Another important aspect of stability is the constant performance of magnetisation. Therefore, the measurement of the magnetisation of the particles must be controlled in order to ensure the stability of the samples.

  7. The operator's emotional stability (United States)

    Zilberman, P. B.


    An attempt is made to provide a psychological interpretation of the concept of emotional stability in connection with other psychics qualities of an operator's personality. Emotional stability is understood as a person's capacity to control his emotional state for the purpose of maintaining the necessary level of work performance under extreme stress conditions. By modeling the operator's sensorimotor activity and by comparing the productivity indicators under ordinary conditions with those obtained during work involving an emotional load, the level of emotional stability can be determined.

  8. 225m Outdoor W-Band Radio-over-Fiber Link Using an Optical SFP+ Module

    DEFF Research Database (Denmark)

    Rommel, Simon; Rodríguez Páez, Juan Sebastián; Chorchos, Łukasz


    A W-band radio-over-fiber link based on a commercial SFP+ module is demonstrated, allowing easy integration into existing PON solutions. Without active laser control good RF frequency stability and 225m wireless distance are achieved...

  9. Nonlinear Resonance Islands and Modulational Effects in a Proton Synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Satogata, Todd Jeffrey [Northwestern Univ., Evanston, IL (United States)


    We examine both one-dimensional and two-dimensional nonlinear resonance islands created in the transverse phase space of a proton synchrotron by nonlinear magnets. We also examine application of the theoretical framework constructed to the phenomenon of modulational diffusion in a collider model of the Fermilab Tevatron. For the one-dimensional resonance island system, we examine the effects of two types of modulational perturbations on the stability of these resonance islands: tune modulation and beta function modulation. Hamiltonian models are presented which predict stability boundaries that depend on only three paramders: the strength and frequency of the modulation and the frequency of small oscillations inside the resonance island. These. models are compared to particle tracking with excellent agreement. The tune modulation model is also successfully tested in experiment, where frequency domain analysis coupled with tune modulation is demonstrated to be useful in measuring the strength of a nonlinear resonance. Nonlinear resonance islands are also examined in two transverse dimensions in the presence of coupling and linearly independent crossing resonances. We present a first-order Hamiltonian model which predicts fixed point locations, but does not reproduce small oscillation frequencies seen in tracking; therefore in this circumstance such a model is inadequate. Particle tracking is presented which shows evidence of two-dimensional persistent signals, and we make suggestions on methods for observing such signals in future experiment.

  10. Cosmetology. Computerized Learning Modules. (United States)

    Finnerty, Kathy, Ed.

    Intended to help reading-limited students meet course objectives, these 11 modules are based on instructional materials in cosmetology that have a higher readability equivalent. Modules cover bacteriology, chemical waving, scalp and hair massage, chemistry, hair shaping, hairstyling, chemical hair relaxing, hair coloring, skin and scalp,…

  11. Growth Modulation in Achondroplasia. (United States)

    McClure, Philip K; Kilinc, Eray; Birch, John G


    Achondroplasia is the most common skeletal dysplasia with a rate of nearly 1/10,000. The development of lower extremity deformity is well documented, and various modes of correction have been reported. There are no reports on the use of growth modulation to correct angular deformity in achondroplasia. Medical Records from 1985 to 2015 were reviewed for the diagnosis of achondroplasia and growth modulation procedures. Patients who had been treated for angular deformity of the legs by growth modulation were identified. A detailed analysis of their medical record and preoperative and final lower extremity radiographs was completed. Four patients underwent growth modulation procedures, all to correct existing varus deformity of the legs. Three of the 4 patients underwent bilateral distal femoral and proximal tibial growth modulation. The remaining patient underwent tibial correction only. Two of the 4 patients had a combined proximal fibular epiphysiodesis. All limbs had some improvement of alignment; however, 1 patient went on to bilateral osteotomies. Only 1 limb corrected to a neutral axis with growth modulation alone at last follow-up, initial implantation was done before 5 years of age. Growth modulation is an effective means for deformity correction in the setting of achondroplasia. However implantation may need to be done earlier than would be typical for patients without achondroplasia. Osteotomy may still be required after growth modulation for incomplete correction.

  12. Core stability exercise principles. (United States)

    Akuthota, Venu; Ferreiro, Andrea; Moore, Tamara; Fredericson, Michael


    Core stability is essential for proper load balance within the spine, pelvis, and kinetic chain. The so-called core is the group of trunk muscles that surround the spine and abdominal viscera. Abdominal, gluteal, hip girdle, paraspinal, and other muscles work in concert to provide spinal stability. Core stability and its motor control have been shown to be imperative for initiation of functional limb movements, as needed in athletics. Sports medicine practitioners use core strengthening techniques to improve performance and prevent injury. Core strengthening, often called lumbar stabilization, also has been used as a therapeutic exercise treatment regimen for low back pain conditions. This article summarizes the anatomy of the core, the progression of core strengthening, the available evidence for its theoretical construct, and its efficacy in musculoskeletal conditions.

  13. Measuring core stability. (United States)

    Liemohn, Wendell P; Baumgartner, Ted A; Gagnon, Laura H


    In this study, a 4-item battery of core stability (CS) tests modeled on core stabilization activities used in training and rehabilitation research was developed, and a measurement schedule was established to maximize internal consistency and stability reliabilities. Specifically, we found that 4 test administrations on each of 4 days produced intraclass correlation coefficients that in most instances exceeded 0.90 and stability reliability coefficients on the third and fourth days of testing that exceeded 0.90 for 2 of the tests and 0.80 for the other 2. Thus, it is recommended that in future research, examiners administer the battery for at least 3 days and consider the data collected on day 3 as the best estimate of participant CS.

  14. PFP solution stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Aftanas, B.L.


    This Functional Design Criteria (FDC) addresses remediation of the plutonium-bearing solutions currently in inventory at the Plutonium Finishing Plant (PFP). The recommendation from the Environmental Impact Statement (EIS) is that the solutions be treated thermally and stabilized as a solid for long term storage. For solutions which are not discardable, the baseline plan is to utilize a denitration process to stabilize the solutions prior to packaging for storage.

  15. Stabilities of generalized entropies


    Abe, Sumiyoshi; Kaniadakis, G.; Scarfone, A. M.


    The generalized entropic measure, which is optimized by a given arbitrary distribution under the constraints on normalization of the distribution and the finite ordinary expectation value of a physical random quantity, is considered and its Lesche stability property (that is different from thermodynamic stability) is examined. A general condition, under which the generalized entropy becomes stable, is derived. Examples known in the literature, including the entropy for the stretched-exponenti...

  16. Fuel Stability Foam (United States)


    The third method is to add liquid chemical stabilizing additives to fuel which is likely to form insoluble products from chemical degradation 1 The treatment choice depends on the storage stability of the fuel and several highly accelerated test methods have been developed to...include carbamate, amide, urea, biuret , isocyanurate and allophanate which may interact with the polar species responsible for deposit formation. PU foams

  17. Food Fortification Stability Study (United States)

    Sirmons, T. A.; Cooper, M. R.; Douglas, G. L.


    This study aimed to assess the stability of vitamin content, sensory acceptability and color variation in fortified spaceflight foods over a period of two years. Findings will help to identify optimal formulation, processing, and storage conditions to maintain stability and acceptability of commercially available fortification nutrients. Changes in food quality were monitored to indicate whether fortification affects quality over time (compared to the unfortified control), thus indicating their potential for use on long-duration missions.

  18. Automatic Fiscal Stabilizers

    Directory of Open Access Journals (Sweden)

    Narcis Eduard Mitu


    Full Text Available Policies or institutions (built into an economic system that automatically tend to dampen economic cycle fluctuations in income, employment, etc., without direct government intervention. For example, in boom times, progressive income tax automatically reduces money supply as incomes and spendings rise. Similarly, in recessionary times, payment of unemployment benefits injects more money in the system and stimulates demand. Also called automatic stabilizers or built-in stabilizers.

  19. Solar energy modulator (United States)

    Hale, R. R. (Inventor); Mcdougal, A. R.


    A module is described with a receiver having a solar energy acceptance opening and supported by a mounting ring along the optic axis of a parabolic mirror in coaxial alignment for receiving solar energy from the mirror, and a solar flux modulator plate for varying the quantity of solar energy flux received by the acceptance opening of the module. The modulator plate is characterized by an annular, plate-like body, the internal diameter of which is equal to or slightly greater than the diameter of the solar energy acceptance opening of the receiver. Slave cylinders are connected to the modulator plate for supporting the plate for axial displacement along the axis of the mirror, therby shading the opening with respect to solar energy flux reflected from the surface of the mirror to the solar energy acceptance opening.

  20. Cyber Deterrence and Stability

    Energy Technology Data Exchange (ETDEWEB)

    Goychayev, Rustam [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carr, Geoffrey A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weise, Rachel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Donnelly, David A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clements, Samuel L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Benz, Jacob M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rodda, Kabrena E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bartholomew, Rachel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McKinnon, Archibald D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Andres, Richard B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)


    Throughout the 20th and early 21st centuries, deterrence and arms control have been cornerstones of strategic stability between the superpowers. However, the weaponization of the cyber realm by State actors and the multipolar nature of cyber conflict now undermines that stability. Strategic stability is the state in which nations believe that if they act aggressively to undermine U.S. national interests and the post-World War II liberal democratic order, the consequences will outweigh the benefits. The sense of lawlessness and lack of consequences in the cyber realm embolden States to be more aggressive in taking actions that undermine stability. Accordingly, this paper examines 1) the role of deterrence and arms control in securing cyber stability, and 2) the limitations and challenges associated with these traditional national security paradigms as applied to this emerging threat domain. This paper demonstrates that many 20th-century deterrence and arms control concepts are not particularly applicable in the cyber realm. However, they are not entirely irrelevant. The United States can distill lessons learned from this rich deterrence and arms control experience to develop and deploy a strategy to advance cyber stability.

  1. Engineering stability in gene networks by autoregulation (United States)

    Becskei, Attila; Serrano, Luis


    The genetic and biochemical networks which underlie such things as homeostasis in metabolism and the developmental programs of living cells, must withstand considerable variations and random perturbations of biochemical parameters. These occur as transient changes in, for example, transcription, translation, and RNA and protein degradation. The intensity and duration of these perturbations differ between cells in a population. The unique state of cells, and thus the diversity in a population, is owing to the different environmental stimuli the individual cells experience and the inherent stochastic nature of biochemical processes (for example, refs 5 and 6). It has been proposed, but not demonstrated, that autoregulatory, negative feedback loops in gene circuits provide stability, thereby limiting the range over which the concentrations of network components fluctuate. Here we have designed and constructed simple gene circuits consisting of a regulator and transcriptional repressor modules in Escherichia coli and we show the gain of stability produced by negative feedback.

  2. Adaptive Differential Thrust Methodology for Lateral/Directional Stability of an Aircraft with a Completely Damaged Vertical Stabilizer

    Directory of Open Access Journals (Sweden)

    Long K. Lu


    Full Text Available This paper investigates the utilization of differential thrust to help a commercial aircraft with a damaged vertical stabilizer in order to regain its lateral/directional stability. In the event of an aircraft losing its vertical stabilizer, the consequential loss of the lateral/directional stability and control is likely to cause a fatal crash. In this paper, an aircraft with a completely damaged vertical stabilizer is investigated, and a unique differential thrust-based adaptive control approach is proposed to achieve a stable flight envelope. The propulsion dynamics of the aircraft is modeled as a system of differential equations with engine time constant and time delay terms to study the engine response time with respect to a differential thrust input. The proposed differential thrust control module is then presented to map the rudder input to differential thrust input. Model reference adaptive control based on the Lyapunov stability approach is implemented to test the ability of the damaged aircraft to track the model aircraft’s (reference response in an extreme scenario. Investigation results demonstrate successful application of such differential thrust approach to regain lateral/directional stability of a damaged aircraft with no vertical stabilizer. Finally, the conducted robustness and uncertainty analysis results conclude that the stability and performance of the damaged aircraft remain within desirable limits and demonstrate a safe flight mission through the proposed adaptive control methodology.

  3. [Lead compound optimization strategy (1)--changing metabolic pathways and optimizing metabolism stability]. (United States)

    Wang, Jiang; Liu, Hong


    Lead compound optimization plays an important role in new drug discovery and development. The strategies for changing metabolic pathways can modulate pharmacokinetic properties, prolong the half life, improve metabolism stability and bioavailability of lead compounds. The strategies for changing metabolic pathways and improving metabolism stability are reviewed. These methods include blocking metabolic site, reduing lipophilicity, changing ring size, bioisosterism, and prodrug.

  4. Resonant frequency stabilization technique in series-series contactless energy transfer systems

    Directory of Open Access Journals (Sweden)

    Marcinek M.


    Full Text Available A technique for stabilization of resonant frequency is proposed in this paper. An additional power circuit, a compensator that allows keeping constant resonance frequency was introduced by the authors. In the presented solution the resonant circuit frequency stabilization is achieved by forcing a zero phase shift between the current and the voltage of the main switching module.

  5. Technical evaluation of Solar Cells, Inc., CdTe module and array at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Kroposki, B.; Strand, T.; Hansen, R. [National Renewable Energy Lab., Golden, CO (United States); Powell, R.; Sasala, R. [Solar Cells, Inc., Toledo, OH (United States)


    The Engineering and Technology Validation Team at the National Renewable Energy Laboratory (NREL) conducts in-situ technical evaluations of polycrystalline thin-film photovoltaic (PV) modules and arrays. This paper focuses on the technical evaluation of Solar Cells, Inc., (SCI) cadmium telluride (CdTe) module and array performance by attempting to correlate individual module and array performance. This is done by examining the performance and stability of the modules and array over a period of more than one year. Temperature coefficients for module and array parameters (P{sub max}, V{sub oc}, V{sub max}, I{sub sc}, I{sub max}) are also calculated.

  6. Grid-connected of photovoltaic module using nonlinear control

    DEFF Research Database (Denmark)

    El Fadil, H.; Giri, F.; Guerrero, Josep M.


    The problem of controlling single-phase grid connected photovoltaic (PV) system is considered. The control objective is fourfold: (i) asymptotic stability of the closed loop system, (ii) maximum power point tracking (MPPT) of PV module (iii) tight regulation of the DC bus voltage, and (iv) unity...

  7. Marble Test. Training Module (United States)

    Bonte, John L.; Davidson, Arnold C.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with the calcium carbonate stability determination by analytical measurements of pH and alkalinity and by calculation from temperature, calcium, alkalinity, and residual measurements. Included are objectives, an instructor guide, student…

  8. Teaching Module for One-Dimensional, Transient Conduction. (United States)

    Ribando, Robert J.; O'Leary, Gerald W.


    Describes a PC-based teaching module designed to instruct engineering students in transient one-dimensional conduction heat transfer analysis. The discussion considers problem formulation, nondimensionalization, discretization, numerical stability and the time-step restriction, program operation, and program verification. (MES)

  9. Photovoltaic module and interlocked stack of photovoltaic modules (United States)

    Wares, Brian S.


    One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame. A plurality of individual male alignment features and a plurality of individual female alignment features are included on each frame. Adjacent photovoltaic modules are interlocked by multiple individual male alignment features on a first module of the adjacent photovoltaic modules fitting into and being surrounded by corresponding individual female alignment features on a second module of the adjacent photovoltaic modules. Other embodiments, features and aspects are also disclosed.

  10. Compact, CO2-stabilized tuneable laser at 2.05 microns

    DEFF Research Database (Denmark)

    Westergaard, Philip G.; Thomsen, Jan W.; Henriksen, Martin Romme


    We demonstrate a compact fibre-based laser system at 2.05 microns stabilized to a CO2 transition using frequency modulation spectroscopy of a gas-filled hollow-core fibre. The laser exhibits an absolute frequency accuracy of 5 MHz, a frequency stability noise floor of better than 7 kHz or 5......×10−11 and is tunable within ±200 MHz from the molecular resonance frequency while retaining roughly this stability and accuracy....

  11. Design Analysis and Implementation of A 0.5 KVA Uninterruptible Power Stabilizer


    Aghanwa Sunny; S.O. Ezeonu; S. O. Ezennaya


    This paper presents design analysis and implementation of a 0.5 KVA uninterruptible electronic power stabilizer (UPSz). Poor and instability of power supply delivery in Nigeria necessitated the need for a device that can stabilize voltage, protect equipment from damages and also provide power to the loads in the absences of electricity from the utility mains. This need motivated the design of a power stabilizer (UPSz). Method of Pulse with modulation (PWM) was adopted. This method is capable ...

  12. Airbag Landing Impact Performance Optimization for the Orion Crew Module (United States)

    Lee, Timothy J.; McKinney, John; Corliss, James M.


    This report will discuss the use of advanced simulation techniques to optimize the performance of the proposed Orion Crew Module airbag landing system design. The Boeing Company and the National Aeronautic and Space Administration s Langley Research Center collaborated in the analysis of the proposed airbag landing system for the next generation space shuttle replacement, the Orion spacecraft. Using LS-DYNA to simulate the Crew Module landing impacts, two main objectives were established and achieved: the investigation of potential methods of optimizing the airbag performance in order to reduce rebound on the anti-bottoming bags, lower overall landing loads, and increase overall Crew Module stability; and the determination of the Crew Module stability and load boundaries using the optimized airbag design, based on the potential Crew Module landing pitch angles and ground slopes in both the center of gravity forward and aft configurations. This paper describes the optimization and stability and load boundary studies and presents a summary of the results obtained and key lessons learned from this analysis.

  13. Stability and diversity of ecosystems. (United States)

    Ives, Anthony R; Carpenter, Stephen R


    Understanding the relationship between diversity and stability requires a knowledge of how species interact with each other and how each is affected by the environment. The relationship is also complex, because the concept of stability is multifaceted; different types of stability describing different properties of ecosystems lead to multiple diversity-stability relationships. A growing number of empirical studies demonstrate positive diversity-stability relationships. These studies, however, have emphasized only a few types of stability, and they rarely uncover the mechanisms responsible for stability. Because anthropogenic changes often affect stability and diversity simultaneously, diversity-stability relationships cannot be understood outside the context of the environmental drivers affecting both. This shifts attention away from diversity-stability relationships toward the multiple factors, including diversity, that dictate the stability of ecosystems.

  14. The ANTARES optical module

    Energy Technology Data Exchange (ETDEWEB)

    Amram, P.; Anghinolfi, M.; Anvar, S.; Ardellier-Desages, F.E.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Bailey, D.; Basa, S.; Battaglieri, M.; Bellotti, R.; Benhammou, Y.; Bernard, F.; Berthier, R.; Bertin, V.; Billault, M.; Blaes, R.; Bland, R.W.; Blondeau, F.; Botton, N. de; Boulesteix, J.; Brooks, C.B.; Brunner, J.; Cafagna, F.; Calzas, A.; Capone, A.; Caponetto, L.; Carloganu, C.; Carmona, E.; Carr, J.; Carton, P.-H.; Cartwright, S.L.; Cassol, F.; Cecchini, S.; Ciacio, F.; Circella, M.; Compere, C.; Cooper, S.; Coyle, P.; Croquette, J.; Cuneo, S.; Danilov, M.; Dantzig, R. van; De Marzo, C.; DeVita, R.; Deck, P.; Destelle, J.-J.; Dispau, G.; Drougou, J.F.; Druillole, F.; Engelen, J.; Feinstein, F.; Festy, D.; Fopma, J.; Gallone, J.-M.; Giacomelli, G.; Goret, P.; Gosset, L.; Gournay, J.-F.; Heijboer, A.; Hernandez-Rey, J.J.; Herrouin, G.; Hubbard, J.R.; Jaquet, M.; Jong, M. de; Karolak, M.; Kooijman, P.; Kouchner, A.; Kudryavtsev, V.A.; Lachartre, D.; Lafoux, H. E-mail:; Lamare, P.; Languillat, J.-C.; Laubier, L.; Laugier, J.-P.; Le Guen, Y.; Le Provost, H.; Le Van Suu, A.; Lemoine, L.; Lo Nigro, L.; Lo Presti, D.; Loucatos, S.; Louis, F.; Lyashuk, V.; Magnier, P.; Marcelin, M.; Margiotta, A.; Massol, A.; Masullo, R.; Mazeas, F.; Mazeau, B.; Mazure, A.; McMillan, J.E.; Michel, J.L.; Migneco, E.; Millot, C.; Mols, P.; Montanet, F.; Montaruli, T.; Morel, J.P.; Moscoso, L.; Musumeci, M.; Navas, S.; Nezri, E.; Nooren, G.J.; Oberski, J.; Olivetto, C.; Oppelt-Pohl, A.; Palanque-Delabrouille, N.; Papaleo, R.; Payre, P.; Perrin, P.; Petruccetti, M.; Petta, C.; Piattelli, P.; Poinsignon, J.; Potheau, R.; Queinec, Y.; Racca, C.; Raia, G.; Randazzo, N.; Rethore, F.; Riccobene, G.; Ricol, J.-S.; Ripani, M.; Roca-Blay, V.; Rolin, J.F.; Rostovstev, A.; Russo, G.V.; Sacquin, Y.; Salusti, E.; Schuller, J.-P.; Schuster, W.; Soirat, J.-P.; Souvorova, O.; Spooner, N.J.C.; Spurio, M.; Stolarczyk, T.; Stubert, D.; Taiuti, M.; Tao, C.; Tayalati, Y.; Thompson, L.F.


    The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km{sup 2} and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R and D studies and is reviewed here in detail.

  15. Optical modulator including grapene

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ming; Yin, Xiaobo; Zhang, Xiang


    The present invention provides for a one or more layer graphene optical modulator. In a first exemplary embodiment the optical modulator includes an optical waveguide, a nanoscale oxide spacer adjacent to a working region of the waveguide, and a monolayer graphene sheet adjacent to the spacer. In a second exemplary embodiment, the optical modulator includes at least one pair of active media, where the pair includes an oxide spacer, a first monolayer graphene sheet adjacent to a first side of the spacer, and a second monolayer graphene sheet adjacent to a second side of the spacer, and at least one optical waveguide adjacent to the pair.

  16. The ANTARES Optical Module

    CERN Document Server

    Amram, P; Anvar, S; Ardellier-Desages, F E; Aslanides, Elie; Aubert, Jean-Jacques; Azoulay, R; Bailey, D; Basa, S; Battaglieri, M; Bellotti, R; Benhammou, Ya; Bernard, F; Berthier, R; Bertin, V; Billault, M; Blaes, R; Bland, R W; Blondeau, F; De Botton, N R; Boulesteix, J; Brooks, B; Brunner, J; Cafagna, F; Calzas, A; Capone, A; Caponetto, L; Cârloganu, C; Carmona, E; Carr, J; Carton, P H; Cartwright, S L; Cassol, F; Cecchini, S; Ciacio, F; Circella, M; Compere, C; Cooper, S; Coyle, P; Croquette, J; Cuneo, S; Danilov, M; Van Dantzig, R; De Marzo, C; De Vita, R; Deck, P; Destelle, J J; Dispau, G; Drougou, J F; Druillole, F; Engelen, J; Feinstein, F; Festy, D; Fopma, J; Gallone, J M; Giacomelli, G; Goret, P; Gosset, L G; Gournay, J F; Heijboer, A; Hernández-Rey, J J; Herrouin, G; Hubbard, John R; Jacquet, M; De Jong, M; Karolak, M; Kooijman, P M; Kouchner, A; Kudryavtsev, V A; Lachartre, D; Lafoux, H; Lamare, P; Languillat, J C; Laubier, L; Laugier, J P; Le Guen, Y; Le Provost, H; Le Van-Suu, A; Lemoine, L; Lo Nigro, L; Lo Presti, D; Loucatos, Sotirios S; Louis, F; Lyashuk, V I; Magnier, P; Marcelin, M; Margiotta, A; Massol, A; Masullo, R; Mazéas, F; Mazeau, B; Mazure, A; McMillan, J E; Michel, J L; Migneco, E; Millot, C; Mols, P; Montanet, François; Montaruli, T; Morel, J P; Moscoso, L; Navas, S; Nezri, E; Nooren, G J L; Oberski, J; Olivetto, C; Oppelt-pohl, A; Palanque-Delabrouille, Nathalie; Payre, P; Perrin, P; Petruccetti, M; Petta, P; Piattelli, P; Poinsignon, J; Popa, V; Potheau, R; Queinec, Y; Racca, C; Raia, G; Randazzo, N; Rethore, F; Riccobene, G; Ricol, J S; Ripani, M; Roca-Blay, V; Rolin, J F; Rostovtsev, A A; Russo, G V; Sacquin, Yu; Salusti, E; Schuller, J P; Schuster, W; Soirat, J P; Suvorova, O; Spooner, N J C; Spurio, M; Stolarczyk, T; Stubert, D; Taiuti, M; Tao, Charling; Tayalati, Y; Thompson, L F; Tilav, S; Triay, R; Valente, V; Varlamov, I; Vaudaine, G; Vernin, P; De Witt-Huberts, P K A; De Wolf, E; Zakharov, V; Zavatarelli, S; De Dios-Zornoza-Gomez, Juan; Zúñiga, J


    The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km-squared and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R & D studies and is reviewed here in detail.

  17. Compact dynatron modulator

    CERN Document Server

    Agafonov, A V


    It is proposed to use a dynatron effect to modulate the voltage across the vacuum inverted coaxial diode with magnetic insulation supplied by an external pulsed high-voltage source connected to the modulator via the RL-circuit. Oscillations of the voltage due to oscillating regime of diode charging and/or azimuthal instability of a rotating electron flow simulates back-bombardment electron flow to the cathode and leads to power spikes of secondary emission current exceeding the primary one. As a result,the amplitude of oscillations grows and the system can turn the modulator and its possible applications.

  18. Interference of serum with lipoplex-cell interaction : modulation of intracellular processing

    NARCIS (Netherlands)

    Zuhorn, I.S; Visser, W.H.; Bakowsky, U.; Engberts, J.B.F.N.; Hoekstra, D


    We have investigated the mechanism of lipoplex-mediated transfection, employing a dialkyl pyridinium surfactant (SAINT-2), and using serum as a modulator of complex stability and processing. Particle size and stability determine lipoplex internalization, the kinetics of intracellular processing, and

  19. A Quantification Index for Power Systems Transient Stability

    Directory of Open Access Journals (Sweden)

    Shengen Chen


    Full Text Available In order to assess the reliability of power systems, transient stability simulations must be conducted in addition to steady state study. The transient stability component of reliability studies usually involves extensive simulations generating large amounts of data to be analyzed. Conventional stability analysis relies on a visual examination of selected simulation data plots to classify the severity of disturbances. This conventional examination, which aims to compare the simulations results to established performance criteria, is not comprehensive, is time consuming and prone to subjective interpretation. This paper presents a quantification method for power system performance evaluation. It applies a range of criteria such as rotor angle separation, loss of source, damping, and voltage sag directly to the simulation data files to achieve a more efficient and objective stability assessment. By using stability modules, the proposed method evaluates the performance of every fault location, numerically, by providing a local stability index, as well as an overall global stability index. The method also provides an evaluation of dispatches and their impacts on system stability. The IEEE 39-bus test system and the Northeast Interconnection Power System were used to show the results of this method. This method will free engineers from tedious, time-consuming and error-susceptible offline visual analysis and yield significantly quantified results.

  20. Hydrodynamic and hydromagnetic stability

    CERN Document Server

    Chandrasekhar, S


    Dr. Chandrasekhar's book received high praise when it first appeared in 1961 as part of Oxford University Press' International Series of Monographs on Physics. Since then it has been reprinted numerous times in its expensive hardcover format. This first lower-priced, sturdy paperback edition will be welcomed by graduate physics students and scientists familiar with Dr. Chandrasekhar's work, particularly in light of the resurgence of interest in the Rayleigh-Bénard problem. This book presents a most lucid introduction to the Rayleigh-Bénard problem: it has also been applauded for its thorough, clear coverage of the theory of instabilities causing convection. Dr. Chandrasekhar considers most of the typical problems in hydromagnetic stability, with the exception of viscous shear flow; a specialized domain deserving a book unto itself. Contents include: Rotation; Stability of More General Flows; Bénard Problem; Gravitational Equilibrium and Instability; Stability of a Magnetic Field; Thermal Instability of a L...

  1. A photovoltaic module

    DEFF Research Database (Denmark)


    The present invention relates to a photovoltaic module comprising a carrier substrate, said carrier substrate carrying a purely printed structure comprising printed positive and negative module terminals, a plurality of printed photovoltaic cell units each comprising one or more printed...... photovoltaic cells, wherein the plurality of printed photovoltaic cell units are electrically connected in series between the positive and the negative module terminals such that any two neighbouring photovoltaic cell units are electrically connected by a printed interconnecting electrical conductor....... The carrier substrate comprises a foil and the total thickness of the photovoltaic module is below 500 [mu]m. Moreover, the nominal voltage level between the positive and the negative terminals is at least 5 kV DC....

  2. Rings and their modules

    CERN Document Server

    Bland, Paul E


    This book is an introduction to the theory of rings and modules that goes beyond what one normally obtains in a graduate course in abstract algebra. In addition to the presentation of standard topics in ring and module theory, it also covers category theory, homological algebra and even more specialized topics like injective envelopes and projective covers, reflexive modules and quasi-Frobenius rings, and graded rings and modules. The book is a self-contained volume written in a very systematic style: allproofs are clear and easy for the reader to understand and allarguments are based onmaterials contained in the book. A problem sets follow each section. It is suitable for graduate and PhD students who have chosen ring theory for their research subject.

  3. CIM - compact intensity modulation.

    Energy Technology Data Exchange (ETDEWEB)

    Bleuel, M.; Lang, E.; Gahler, G.; Lal, J.; Intense Pulsed Neutron Source; Inst. Lau Langevin


    Compact intensity modulation (CIM), a new method to modulate the intensity of a neutron beam is demonstrated. CIM allows the production of arbitrary signals where the focus point can be chosen and changed without any constraints. A novel feature in this technique compared to spin echo techniques is that the neutron polarization is kept parallel or anti-parallel to the static fields during the passage through the magnetic fields and the beating pattern at the detector is produced by an amplitude modulation (AM) of the adiabatic RF-spin flippers rather than Larmor precession like in neutron spin echo (NSE) instruments; thus, the achievable contrast is very high and the instrument resolution can be changed very quickly. This gives the fascinating possibility at pulsed neutron sources to sweep the modulation frequency of the flippers in order to increase dynamic resolution range during the same neutron pulse.

  4. Specification du module FIPADUC

    CERN Document Server

    Brun, R


    FIPADUC est un module WorldFIP intelligent et generique construit autour d'un microcontroleur ADUC834 et d'une interface de communication WorldFIP basee sur une technologie MICROFIP. Il est prevu pour des applications reduites devant resister aux radiations (minimum 200Gry). Ce module sera dedie a l'acquisition d'entrees/sorties et constituera une base d'interfacage intelligente WorldFIP.

  5. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice


    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  6. Dynamic Stabilization of the Ablative Rayleigh-Taylor Instability for Heavy Ion Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Hong; Davidson, Ronald C.; Logan, B. Grant


    Dynamic stabilization of the ablative Rayleigh-Taylor instability of a heavy ion fusion target induced by a beam wobbling system is studied. Using a sharp-boundary model and Courant-Synder theory, it is shown, with an appropriately chosen modulation waveform, that the instability can be sta- bilized in certain parameter regimes. It is found that the stabilization e ect has a strong dependence on the modulation frequency and the waveform. Modulation with frequency comparable to the instability growth rate is the most e ective in terms of stabilizing the instability. A modulation with two frequency components can result in a reduction of the growth rate larger than the sum of that due to the two components when applied separately.

  7. Progress on plutonium stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Hurt, D. [Defense Nuclear Facilities Safety Board, Washington, DC (United States)


    The Defense Nuclear Facilities Safety Board has safety oversight responsibility for most of the facilities where unstable forms of plutonium are being processed and packaged for interim storage. The Board has issued recommendations on plutonium stabilization and has has a considerable influence on DOE`s stabilization schedules and priorities. The Board has not made any recommendations on long-term plutonium disposition, although it may get more involved in the future if DOE develops plans to use defense nuclear facilities for disposition activities.

  8. Chromium and Genomic Stability (United States)

    Wise, Sandra S.; Wise, John Pierce


    Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There are no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as highly toxic and carcinogenic with no nutritional value. Recent data indicate that it causes genomic instability and also has no role in promoting genomic stability. PMID:22192535

  9. Stability of dynamical systems

    CERN Document Server

    Liao, Xiaoxin; Yu, P 0


    The main purpose of developing stability theory is to examine dynamic responses of a system to disturbances as the time approaches infinity. It has been and still is the object of intense investigations due to its intrinsic interest and its relevance to all practical systems in engineering, finance, natural science and social science. This monograph provides some state-of-the-art expositions of major advances in fundamental stability theories and methods for dynamic systems of ODE and DDE types and in limit cycle, normal form and Hopf bifurcation control of nonlinear dynamic systems.ʺ Presents

  10. Magnetohydrodynamic stability of tokamaks

    CERN Document Server

    Zohm, Hartmut


    This book bridges the gap between general plasma physics lectures and the real world problems in MHD stability. In order to support the understanding of concepts and their implication, it refers to real world problems such as toroidal mode coupling or nonlinear evolution in a conceptual and phenomenological approach. Detailed mathematical treatment will involve classical linear stability analysis and an outline of more recent concepts such as the ballooning formalism. The book is based on lectures that the author has given to Master and PhD students in Fusion Plasma Physics. Due its strong lin

  11. Photovoltaic module reliability workshop (United States)

    Mrig, L.

    The paper and presentations compiled in this volume form the Proceedings of the fourth in a series of Workshops sponsored by Solar Energy Research Institute (SERI/DOE) under the general theme of photovoltaic module reliability during the period 1986 to 1990. The reliability photovoltaic (PV) modules/systems is exceedingly important along with the initial cost and efficiency of modules if the PV technology has to make a major impact in the power generation market, and for it to compete with the conventional electricity producing technologies. The reliability of photovoltaic modules has progressed significantly in the last few years as evidenced by warrantees available on commercial modules of as long as 12 years. However, there is still need for substantial research and testing required to improve module field reliability to levels of 30 years or more. Several small groups of researchers are involved in this research, development, and monitoring activity around the world. In the U.S., PV manufacturers, DOE laboratories, electric utilities and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in this field were brought together under SERI/DOE sponsorship to exchange the technical knowledge and field experience as related to current information in this important field. The papers presented here reflect this effort.

  12. Photovoltaic module reliability workshop

    Energy Technology Data Exchange (ETDEWEB)

    Mrig, L. (ed.)


    The paper and presentations compiled in this volume form the Proceedings of the fourth in a series of Workshops sponsored by Solar Energy Research Institute (SERI/DOE) under the general theme of photovoltaic module reliability during the period 1986--1990. The reliability Photo Voltaic (PV) modules/systems is exceedingly important along with the initial cost and efficiency of modules if the PV technology has to make a major impact in the power generation market, and for it to compete with the conventional electricity producing technologies. The reliability of photovoltaic modules has progressed significantly in the last few years as evidenced by warranties available on commercial modules of as long as 12 years. However, there is still need for substantial research and testing required to improve module field reliability to levels of 30 years or more. Several small groups of researchers are involved in this research, development, and monitoring activity around the world. In the US, PV manufacturers, DOE laboratories, electric utilities and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in this field were brought together under SERI/DOE sponsorship to exchange the technical knowledge and field experience as related to current information in this important field. The papers presented here reflect this effort.

  13. Responsiveness of emulsions stabilized by lactoferrin nano-particles to simulated intestinal conditions. (United States)

    Meshulam, Dafna; Lesmes, Uri


    There is an upsurge of interest in the use of nano-particles to fabricate emulsions and modulate their functionality, with particular emphasis on modulating emulsion digestive fate. Food grade nano-particles formed through controlled processing and electrostatic biopolymer interactions are yet to be systematically studied for their ability to stabilize emulsions and modulate emulsion digestibility. This study focused on the responsiveness of emulsions stabilized by lactoferrin (LF) nano-particles (NPs) and dietary fibers to key digestive parameters. Compared to native LF, LF-NPs comprised emulsion exhibited elevated creaming rates as evident from accelerated stability tests performed by analytical centrifugation. The electrostatic deposition of alginate or carrageenan onto the LF-NPs significantly improved the stability of the corresponding emulsions. Further, the use of various nano-particles showed to have both beneficial and deleterious effects on emulsion responsiveness to pH (2.0 nano-particles to tweak emulsion behavior during digestion.

  14. Stress Modulation of Fracture Fixation Implants. (United States)

    Beltran, Michael J; Collinge, Cory A; Gardner, Michael J


    Stress modulation is the concept of manipulating bridge plate variables to provide a flexible fixation construct that allows callus formation through uneventful secondary bone healing. Obtaining absolute stability through the anatomic reduction of all fracture fragments comes at the expense of fracture biology, whereas intramedullary nailing, which is more advantageous for diaphyseal fractures of the lower extremity, is technically demanding and often may not be possible when stabilizing many metaphyseal fractures. Overly stiff plating constructs are associated with asymmetric callus formation, early implant failure, and fracture nonunion. Numerous surgeon-controlled variables can be manipulated to increase flexibility without sacrificing strength, including using longer plates with well-spaced screws, choosing titanium or stainless steel implants, and using locking or nonlocking screws. Axially dynamic emerging concepts, such as far cortical locking and near cortical overdrilling, provide further treatment options when bridge plating techniques are used.

  15. Apollo 9 Command/Service Modules photographed from Lunar Module (United States)


    The Apollo 9 Command/Service Modules photographed from the Lunar Module, 'Spider', on the fifth day of the Apollo 9 earth-orbital mission. Docking mechanism is visible in nose of the Command Module, 'Gumdrop'. Object jutting out from the Service Module aft bulkhead is the high-gain S-Band antenna.

  16. Human Cytosolic Extracts Stabilize the HIV-1 Core (United States)

    Fricke, Thomas; Brandariz-Nuñez, Alberto; Wang, Xiaozhao; Smith, Amos B.


    The stability of the HIV-1 core in the cytoplasm is crucial for productive HIV-1 infection. Mutations that stabilize or destabilize the core showed defects on HIV-1 reverse transcription and infection. We developed a novel and simple assay to measure the stability of in vitro-assembled HIV-1 CA-NC complexes. The assay allowed us to demonstrate that cytosolic extracts strongly stabilize the HIV-1 core. Interestingly, stabilization of in vitro-assembled HIV-1 CA-NC complexes is not due solely to macromolecular crowding, suggesting the presence of specific cellular factors that stabilize the HIV-1 core. By using our novel assay, we measured the abilities of different drugs, such as PF74, CAP-1, IXN-053, cyclosporine, Bi2 (also known as BI-2), and the peptide CAI, to modulate the stability of in vitro-assembled HIV-1 CA-NC complexes. Interestingly, we found that PF74 and Bi2 strongly stabilized HIV-1 CA-NC complexes. On the other hand, the peptide CAI destabilized HIV-1 CA-NC complexes. We also found that purified cyclophilin A destabilizes in vitro-assembled HIV-1 CA-NC complexes in the presence of cellular extracts in a cyclosporine-sensitive manner. In agreement with previous observations using the fate-of-the-capsid assay, we also demonstrated the ability of recombinant CPSF6 to stabilize HIV-1 CA-NC complexes. Overall, our findings suggested that cellular extracts specifically stabilize the HIV-1 core. We believe that our assay can be a powerful tool to assess HIV-1 core stability in vitro. PMID:23885082

  17. Effect of moisture on polyvinylpyrrolidone in accelerated stability testing. (United States)

    Fitzpatrick, Shaun; McCabe, James F; Petts, Catherine R; Booth, Steven W


    Accelerated stability studies are a common approach for predicting the long-term stability of pharmaceutical formulations. However, in this study, a slowing of dissolution was observed for a formulation following storage at elevated temperature and humidity. The moisture sorption isotherm for the binder, polyvinylpyrrolidone (PVP), shows absorption of a significant quantity of water on exposure to elevated humidity. Modulated temperature differential scanning calorimetry (mDSC) has been used to demonstrate that moisture uptake will depress the glass transition temperature (Tg) of PVP to the conditions used in accelerated stability studies. Exposure to elevated temperature and humidity resulted in a change in the PVP from the glassy to the rubbery state. This conversion produces a change in the dissolution profile. Long-term stability studies conducted at temperatures and humidities below the Tg, would not have induced this change.

  18. Stability through cycles

    NARCIS (Netherlands)

    Groot, de E.A. (Bert); Franses, P.H.P.H.


    Economic variables like GDP growth, employment, interest rates and consumption show signs of cyclical behavior. Many variables display multiple cycles, with lengths ranging in between 5 to even up to 100 years. We argue that multiple cycles can be associated with long-run stability of the economic

  19. Orbit Stabilization of Nanosat

    Energy Technology Data Exchange (ETDEWEB)



    An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.

  20. Linearity stabilizes discrete breathers

    Indian Academy of Sciences (India)


    Nov 27, 2015 ... Here we study the dynamics of highly localized excitations, or discrete breathers, which are known to be initiated by the quasistatic stretching of bonds between adjacent particles. We show via dynamical simulations that acoustic waves introduced by the harmonic term stabilize the discrete breather by ...

  1. The Dynamics of Stability

    DEFF Research Database (Denmark)

    Hedegaard, Troels Fage

    politiske aktører der greb disse muligheder. Disse historiske faktorer, der hjalp med at skabe opbakning til velfærdsstaten, er dog blevet svækket med tiden, mens støtten til modellen forbliver stabil. Denne umiddelbare modsætning er denne afhandlings omdrejningspunkt. Derfor vender jeg I denne afhandling...

  2. Integrated unaligned resonant modulator tuning (United States)

    Zortman, William A.; Lentine, Anthony L.


    Methods and systems for tuning a resonant modulator are disclosed. One method includes receiving a carrier signal modulated by the resonant modulator with a stream of data having an approximately equal number of high and low bits, determining an average power of the modulated carrier signal, comparing the average power to a predetermined threshold, and operating a tuning device coupled to the resonant modulator based on the comparison of the average power and the predetermined threshold. One system includes an input structure, a plurality of processing elements, and a digital control element. The input structure is configured to receive, from the resonant modulator, a modulated carrier signal. The plurality of processing elements are configured to determine an average power of the modulated carrier signal. The digital control element is configured to operate a tuning device coupled to the resonant modulator based on the average power of the modulated carrier signal.

  3. Control Performance of Vehicle Abs Featuring ER Valve Pressure Modulator (United States)

    Cho, M. S.; Choi, S. B.; Wereley, N. M.

    In this work, an electrically controllable anti-lock brake system (ABS) for passenger vehicle is developed by utilizing electrorheological (ER) fluid. A pressure modulator which consists of a cylindrical ER valve and the hydraulic booster is constructed in order to achieve sufficient brake pressure variation during ABS operation. The principal design parameters of the modulator are determined by considering ER properties as well as required braking pressure. After investigating pressure controllability of the modulator, a vehicle model which is integrated with the proposed pressure modulator is formulated to design yaw rate controller. A sliding mode controller is designed to obtain desired yaw rate, and the friction forces between roads and wheels are estimated via the estimator. Braking performances of the proposed ABS under various roads are evaluated through the hardware-in-the-loop-simulation (HILS) and the steering stability during braking operation is demonstrated by undertaking split-μ test.

  4. Nonlinear Langmuir Wave Modulation in Weakly Magnetized Plasmas

    DEFF Research Database (Denmark)

    Dysthe, K. B.; Pécseli, Hans


    It is assumed that the magnetic field is only important for the ion motion. Both a fluid and a kinetic description of the ions are considered. It is found that the presence of electrostatic ion cyclotron waves, in addition to the ion acoustic waves also found in unmagnetized plasmas, has a strong...... varying electron heating in the amplitude modulated Langmuir wave. For modulations travelling almost perpendicular to the magnetic field, this effect has a profound influence on a modulational instability...... influence on the modulation stability of plane Langmuir waves. As in the unmagnetized case, kinetic results were found to deviate considerably from those obtained by using a fluid description for the ion dynamics. With particular attention to ionospheric phenomena, the effect is included of the spatially...

  5. NREL module energy rating methodology

    Energy Technology Data Exchange (ETDEWEB)

    Whitaker, C.; Newmiller, J.; Kroposki, B. [National Renewable Energy Laboratory, Golden, CO (United States)] [and others


    The goals of this project were to develop a tool for: evaluating one module in different climates; comparing different modules; provide a Q&D method for estimating periodic energy production; provide an achievable module rating; provide an incentive for manufacturers to optimize modules to non-STC conditions; and to have a consensus-based, NREL-sponsored activity. The approach taken was to simulate module energy for five reference days of various weather conditions. A performance model was developed.

  6. Central α- and β-thujone: similar anxiogenic-like effects and differential modulation on GABAA receptors in neonatal chicks. (United States)

    Rivera, E M; Cid, M P; Zunino, P; Baiardi, G; Salvatierra, N A


    The convulsant effects of α-thujone are attributed to inhibitory actions on the GABAA receptor. We investigated, for the first time, the effects of α-thujone or β-thujone administrated centrally on the fear/anxiety behaviour of 3-day-old chicks in an Open Field and their modulation on the GABAA receptor. Higher doses were convulsant by eliciting a toxic and excitatory action, with the results showing that a dose of 78 nmol of either of the two diastereoisomers had an anxiogenic-like effect observed as an increased latency to ambulate and a reduced locomotor activity in an Open Field. Nevertheless, only the central administration of α-thujone reversed the increase induced by acute stress in the flunitrazepam-sensitive GABAA receptor recruitment. These findings demonstrated that α-thujone, when intracerebroventricularly administered, suppressed the GABAA receptor recruitment induced by acute stress, maybe due to α-thujone blocking the benzodiazepine binding site or another site of the GABAA complex. However, it should not be discarded that acute stress associated with novelty may have induced the recruitment of a subpopulation of GABAA receptors more sensitive to α-thujone than to the constitutive receptors, or that this monoterpene could have inhibited any protein or enzyme trafficking that modulated the phosphorylation of the receptor involved in the turnover of GABAA receptor. β-Thujone showed behavioural effects similar to its diastereoisomer α-thujone. However, its action mechanism may have been mediated by other neurotransmitter systems, such as the serotonergic one or by a different biological effectiveness due to a distinct stereochemistry at the specific site of the GABAA receptor. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Surface-stabilized gold nanocatalysts (United States)

    Dai, Sheng [Knoxville, TN; Yan, Wenfu [Oak Ridge, TN


    A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.

  8. The Strip Module

    DEFF Research Database (Denmark)

    Pedersen, Tommy


    When the behaviour of a ship in waves is to be predicted it is convenient to have a tool which includes different approaches to the problem.The aim of this project is to develop such a tool named the strip theory module. The strip theory module will consist of submodules dependent on the I-ship...... code available at the department. It will be structured as a general preprocessor mainly to determine the hydrodynamic mass and damping. A strip processor including three different theories: A linear frequency domain strip theory, a quadratic strip theory and a nonlinear time domain strip theory....... At last a postprocessor will be included with facilities for statistical calculations and for plots and prints of the results.The project is divided into 7 tasks where the third is to be completed.This report has two aims. To give an introduction to the project of developing a strip theory module...

  9. GREET Pretreatment Module

    Energy Technology Data Exchange (ETDEWEB)

    Adom, Felix K. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Han, Jeongwoo [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division


    A wide range of biofuels and biochemicals can be produced from cellulosic biomass via different pretreatment technologies that yield sugars. Process simulations of dilute acid and ammonia fiber expansion pretreatment processes and subsequent hydrolysis were developed in Aspen Plus for four lignocellulosic feedstocks (corn stover, miscanthus, switchgrass, and poplar). This processing yields sugars that can be subsequently converted to biofuels or biochemical. Material and energy consumption data from Aspen Plus were then compiled in a new Greenhouses Gases, Regulated Emissions, and Energy Use in Transportation (GREETTM) pretreatment module. The module estimates the cradle-to-gate fossil energy consumption (FEC) and greenhouse gas (GHG) emissions associated with producing fermentable sugars. This report documents the data and methodology used to develop this module and the cradle-to-gate FEC and GHG emissions that result from producing fermentable sugars.

  10. Power module assembly (United States)

    Campbell, Jeremy B [Torrance, CA; Newson, Steve [Redondo Beach, CA


    A power module assembly of the type suitable for deployment in a vehicular power inverter, wherein the power inverter has a grounded chassis, is provided. The power module assembly comprises a conductive base layer electrically coupled to the chassis, an insulating layer disposed on the conductive base layer, a first conductive node disposed on the insulating layer, a second conductive node disposed on the insulating layer, wherein the first and second conductive nodes are electrically isolated from each other. The power module assembly also comprises a first capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the first conductive node, and further comprises a second capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the second conductive node.

  11. India's INDC for transport and 2 C stabilization target

    DEFF Research Database (Denmark)

    Dhar, Subash; Shukla, Priyadarshi Ramprasad; Pathak, Minal


    infrastructures, sustainable logistics and inland waterways to achieve these reductions. The Paris agreement that followed the announcement of the INDC increased the global ambition to stabilize the greenhouse gases so that maximum temperature rise is limited to 2 ?C with an enhanced ambition for 1.5 ?C....... The paper analyses how far INDC will reduce the emissions from transport and to what extent a 2 ?C temperature stabilization goal will decarbonize the transport sector. The analysis is carried out using ANSWER MARKAL model for evaluating the energy system in combination with a transport demand module...

  12. Optimization and Design of a Low Power Switched Current A/D Sigma-Delta-Modulator for Voice Band Applications

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur


    This paper presents a third order switched current sigma delta-modulator. The modulator is optimized at the system level for minimum power consumption by careful design of the noise transfer function. A thorough noise analysis of the cascode type current copiers used to implement the modulator...... to internal clamping in the integrators and proper scaling the modulator shows excellent stability properties. In order to compare the performance of the modulator presented in this paper to other sigma delta-modulators two figure-of-merits (FOMs) are proposed. From these figure-of-merits it is found...... that the performance of the modulator presented in this paper is significantely higher than the perforamce of other switched current sigma delta-modulators reported. Also, the figure-of-merits show that the performance is comparable to the performance of reported switched capacitor sigma delta-modulators....

  13. Optimized Feature Extraction for Temperature-Modulated Gas Sensors

    Directory of Open Access Journals (Sweden)

    Alexander Vergara


    Full Text Available One of the most serious limitations to the practical utilization of solid-state gas sensors is the drift of their signal. Even if drift is rooted in the chemical and physical processes occurring in the sensor, improved signal processing is generally considered as a methodology to increase sensors stability. Several studies evidenced the augmented stability of time variable signals elicited by the modulation of either the gas concentration or the operating temperature. Furthermore, when time-variable signals are used, the extraction of features can be accomplished in shorter time with respect to the time necessary to calculate the usual features defined in steady-state conditions. In this paper, we discuss the stability properties of distinct dynamic features using an array of metal oxide semiconductors gas sensors whose working temperature is modulated with optimized multisinusoidal signals. Experiments were aimed at measuring the dispersion of sensors features in repeated sequences of a limited number of experimental conditions. Results evidenced that the features extracted during the temperature modulation reduce the multidimensional data dispersion among repeated measurements. In particular, the Energy Signal Vector provided an almost constant classification rate along the time with respect to the temperature modulation.

  14. Hillslope hydrology and stability (United States)

    Lu, Ning; Godt, Jonathan


    Landslides are caused by a failure of the mechanical balance within hillslopes. This balance is governed by two coupled physical processes: hydrological or subsurface flow and stress. The stabilizing strength of hillslope materials depends on effective stress, which is diminished by rainfall. This book presents a cutting-edge quantitative approach to understanding hydro-mechanical processes across variably saturated hillslope environments and to the study and prediction of rainfall-induced landslides. Topics covered include historic synthesis of hillslope geomorphology and hydrology, total and effective stress distributions, critical reviews of shear strength of hillslope materials and different bases for stability analysis. Exercises and homework problems are provided for students to engage with the theory in practice. This is an invaluable resource for graduate students and researchers in hydrology, geomorphology, engineering geology, geotechnical engineering and geomechanics and for professionals in the fields of civil and environmental engineering and natural hazard analysis.

  15. Marital stability and repartnering

    DEFF Research Database (Denmark)

    Martins, Mariana V; Costa, Patrício; Peterson, Brennan D


    OBJECTIVE: To compare the trajectories of infertility-related stress between patients who remain in the same relationship and patients who repartner. DESIGN: Longitudinal cohort study using latent growth modeling. SETTING: Fertility centers. PATIENT(S): Childless men and women evaluated before...... starting a new cycle of fertility treatment and observed for a 5-year period of unsuccessful treatments. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Marital stability and infertility-related stress. RESULT(S): The majority of patients (86%) remained with their initial partner, but 14% of participants...... separated and repartnered while pursuing fertility treatments. Marital stability significantly predicted the initial status of infertility stress and infertility stress growth levels. Specifically, patients who repartnered had higher infertility stress levels at all time points compared with those who...

  16. Dynamically stabilized magnetic skyrmions (United States)

    Zhou, Y.; Iacocca, E.; Awad, A. A.; Dumas, R. K.; Zhang, F. C.; Braun, H. B.; Åkerman, J.


    Magnetic skyrmions are topologically non-trivial spin textures that manifest themselves as quasiparticles in ferromagnetic thin films or noncentrosymmetric bulk materials. So far attention has focused on skyrmions stabilized either by the Dzyaloshinskii-Moriya interaction (DMI) or by dipolar interaction, where in the latter case the excitations are known as bubble skyrmions. Here we demonstrate the existence of a dynamically stabilized skyrmion, which exists even when dipolar interactions and DMI are absent. We establish how such dynamic skyrmions can be nucleated, sustained and manipulated in an effectively lossless medium under a nanocontact. As quasiparticles, they can be transported between two nanocontacts in a nanowire, even in complete absence of DMI. Conversely, in the presence of DMI, we observe that the dynamical skyrmion experiences strong breathing. All of this points towards a wide range of skyrmion manipulation, which can be studied in a much wider class of materials than considered so far.

  17. Stability of Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, F.; Schiek, M.; Wallmann, I.


    The morphological stability of organic nanowires over time and under thermal load is of major importance for their use in any device. In this study the growth and stability of organic nanowires from a naphthyl end-capped thiophene grown by organic molecular beam deposition is investigated via...... atomic force microscopy (AFM). Aging experiments under ambient conditions already show substantial morphological changes. Nanoscopic organic clusters, which initially coexist with the nanowires, vanish within hours. Thermal annealing of nanowire samples leads to even more pronounced morphology changes......, such as a strong decrease in nanowire number density, a strong increase in nanowire height, and the formation of new types of crystallites. This happens even before sublimation of organic material starts. These experiments also shine new light on the formation process of the nanowires....

  18. Glycosylation and thermodynamic versus kinetic stability of horseradish peroxidase

    DEFF Research Database (Denmark)

    Tams, J.W.; Welinder, Karen G.


    Glycoprotein stability, glycoprotein unfolding, horseradish peroxidase, thermodynamic stability, kinetik stability......Glycoprotein stability, glycoprotein unfolding, horseradish peroxidase, thermodynamic stability, kinetik stability...

  19. Limits of Nuclear Stability

    CERN Document Server

    Nerlo-Pomorska, B; Kleban, M


    The modern version of the liquid-drop model (LSD) is compared with the macroscopic part of the binding energy evaluated within the Hartree-Fock- Bogoliubov procedure with the Gogny force and the relativistic mean field theory. The parameters of a liquid-drop like mass formula which approximate on the average the self-consistent results are compared with other models. The limits of nuclear stability predicted by these models are discussed.

  20. Chromium and Genomic Stability


    Wise, Sandra S.; Wise, John Pierce


    Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There are no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as high...

  1. Heterotic moduli stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Cicoli, M. [Bologna Univ. (Italy). Dipt. Fisica ed Astronomia; INFN, Bologna (Italy); Adbus Salam ICTP, Trieste (Italy); De Alwis, S. [Adbus Salam ICTP, Trieste (Italy); Colorado Univ., Boulder, CO (United States). UCB 390 Physics Dept.; Westphal, A. [DESY Hamburg (Germany). Theory Group


    We perform a systematic analysis of moduli stabilization for weakly coupled heterotic string theory compactified on smooth Calabi-Yau three-folds. We focus on both supersymmetric and supersymmetry breaking vacua of generic (0,2) compactifications obtained by minimising the total (F+D)-term scalar potential. After reviewing how to stabilise all the geometric moduli in a supersymmetric way by including fractional fluxes, non-perturbative and threshold effects, we show that the inclusion of {alpha}' corrections leads to new de Sitter or nearly Minkowski vacua which break supersymmetry spontaneously. The minimum lies at moderately large volumes of all the geometric moduli, at perturbative values of the string coupling and at the right phenomenological value of the GUT gauge coupling. However the structure of the heterotic 3-form flux used for complex structure moduli stabilization does not contain enough freedom to tune the superpotential. This results in the generic prediction of high-scale supersymmetry breaking around the GUT scale. We finally provide a dynamical derivation of anisotropic compactifications with stabilized moduli which allow for perturbative gauge coupling unification around 10{sup 16} GeV.

  2. Vibrational stability of graphene

    Directory of Open Access Journals (Sweden)

    Yangfan Hu


    Full Text Available The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP models. Compared with three-dimensional (3-D materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202. This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC, defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D materials.

  3. Improved roof stabilization technologies

    Energy Technology Data Exchange (ETDEWEB)

    Ebadian, M.A.


    Decontamination and decommissioning (D and D) activities require that personnel have access to all areas of structures, some of which are more than 40 years old. In many cases, these structures have remained in a standby condition for up to 10 years; few preventative maintenance activities have been performed on them because of lack of funding or a defined future plan of action. This situation has led to deteriorated building conditions, resulting in potential personnel safety hazards. In addition, leaky roofs allow water to enter the buildings, which can cause the spread of contamination and increase building deterioration, worsening the already unsafe working conditions. To ensure worker safety and facilitate building dismantlement, the assessment of roof stabilization techniques applicable to US Department of Energy (DOE) structures has become an important issue. During Fiscal year 1997 (FY97), a comprehensive reliability-based model for the structural stabilization analysis of roof system in complex structures was developed. The model consists of three major components: a material testing method, a deterministic structural computer model, and a reliability-based optimization, and probabilistic analyses of roof structures can be implemented. Given site-specific needs, this model recommends the most appropriate roof stabilization system. This model will give not only an accurate evaluation of the existing roof system in complex structures, but it will also be a reliable method to aid the decision-making process. This final report includes in its appendix a Users` Manual for the Program of Deterministic and Reliability Analysis of Roof Structures.

  4. Nuclear magnetic resonance studies of an N2-guanine adduct derived from the tumorigen dibenzo[a,l]pyrene in DNA: impact of adduct stereochemistry, size, and local DNA sequence on solution conformations. (United States)

    Rodríguez, Fabián A; Liu, Zhi; Lin, Chin H; Ding, Shuang; Cai, Yuqin; Kolbanovskiy, Alexander; Kolbanovskiy, Marina; Amin, Shantu; Broyde, Suse; Geacintov, Nicholas E


    The dimensions and arrangements of aromatic rings (topology) in adducts derived from the reactions of polycyclic aromatic hydrocarbon (PAH) diol epoxide metabolites with DNA influence the distortions and stabilities of double-stranded DNA, and hence their recognition and processing by the human nucleotide excision repair (NER) system. Dibenzo[a,l]pyrene (DB[a,l]P) is a highly tumorigenic six-ring PAH, which contains a nonplanar and aromatic fjord region that is absent in the structurally related bay region five-ring PAH benzo[a]pyrene (B[a]P). The PAH diol epoxide-DNA adducts formed include the stereoisomeric 14S and 14R trans-anti-DB[a,l]P-N(2)-dG and the stereochemically analogous 10S- and 10R-B[a]P-N(2)-dG (B[a]P-dG) guanine adducts. However, nuclear magnetic resonance (NMR) solution studies of the 14S-DB[a,l]P-N(2)-dG adduct in DNA have not yet been presented. Here we have investigated the 14S-DB[a,l]P-N(2)-dG adduct in two different sequence contexts using NMR methods with distance-restrained molecular dynamics simulations. In duplexes with dC opposite the adduct deleted, a well-resolved base-displaced intercalative adduct conformation can be observed. In full duplexes, in contrast to the intercalated 14R stereoisomeric adduct, the bulky DB[a,l]P residue in the 14S adduct is positioned in a greatly widened and distorted minor groove, with significant disruptions and distortions of base pairing at the lesion site and two 5'-side adjacent base pairs. These unique structural features are significantly different from those of the stereochemically analogous but smaller B[a]P-dG adduct. The greater size and different topology of the DB[a,l]P aromatic ring system lead to greater structurally destabilizing DNA distortions that are partially compensated by stabilizing DB[a,l]P-DNA van der Waals interactions, whose combined effects impact the NER response to the adduct. These structural results broaden our understanding of the structure-function relationship in NER.

  5. Improving Small Signal Stability through Operating Point Adjustment

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenyu; Zhou, Ning; Tuffner, Francis K.; Chen, Yousu; Trudnowski, Daniel J.; Mittelstadt, William; Hauer, John F.; Dagle, Jeffery E.


    ModeMeter techniques for real-time small signal stability monitoring continue to mature, and more and more phasor measurements are available in power systems. It has come to the stage to bring modal information into real-time power system operation. This paper proposes to establish a procedure for Modal Analysis for Grid Operations (MANGO). Complementary to PSS’s and other traditional modulation-based control, MANGO aims to provide suggestions such as increasing generation or decreasing load for operators to mitigate low-frequency oscillations. Different from modulation-based control, the MANGO procedure proactively maintains adequate damping for all time, instead of reacting to disturbances when they occur. Effect of operating points on small signal stability is presented in this paper. Implementation with existing operating procedures is discussed. Several approaches for modal sensitivity estimation are investigated to associate modal damping and operating parameters. The effectiveness of the MANGO procedure is confirmed through simulation studies of several test systems.

  6. ALICE silicon strip module

    CERN Multimedia

    Maximilien Brice


    This small silicon detector strip will be inserted into the inner tracking system (ITS) on the ALICE detector at CERN. This detector relies on state-of-the-art particle tracking techniques. These double-sided silicon strip modules have been designed to be as lightweight and delicate as possible as the ITS will eventually contain five square metres of these devices.

  7. Drupal Contributed Modules

    Energy Technology Data Exchange (ETDEWEB)


    These Drupal Modules extend the functionality of Drupal by including specific styles for dates and tabs, publishing options for scheduled and immediate publication of content modes, field visibility in content forms, keyword block filters (taxonomy based), adding content nodes to a specified queue for display in views, and status display of workflow settings.

  8. Modelling the Photovoltaic Module

    DEFF Research Database (Denmark)

    Katsanevakis, Markos


    This paper refers into various ways in simulation the Photovoltaic (PV) module behaviour under any combination of solar irradiation and ambient temperature. There are three different approaches presented here briefly and one of them is chosen because of its good accuracy and relatively low...

  9. Transformations of CLP Modules

    NARCIS (Netherlands)

    Etalle, Sandro; Gabbrielli, Maurizio


    We propose a transformation system for Constraint Logic Programming (CLP) aprograms and modules. The framework is inspired by the one of [37] for pure logic programs. However, the use of CLP allows us to introduce some new operations such as splitting and constraint replacement. We provide two sets

  10. Transformations of CLP modules

    NARCIS (Netherlands)

    S. Etalle (Sandro); M. Gabbrielli


    textabstractWe propose a transformation system for CLP programs and modules. The framework is inspired by the one of Tamaki and Sato for pure logic programs. However, the use of CLP allows us to introduce some new operations such as splitting and constraint replacement. We provide two sets of

  11. An Integrated Teaching Module. (United States)

    Samuel, Marie R.; Seiferth, Berniece B.

    This integrated teaching module provides elementary and junior high school teachers with a "hands-on" approach to studying the Anasazi Indian. Emphasis is on creative exploration that focuses on integrating art, music, poetry, writing, geography, dance, history, anthropology, sociology, and archaeology. Replicas of artifacts,…

  12. Paratransit: An Instructional Module. (United States)

    Scalici, Anthony

    A concept-based introduction to paratransit is provided in this instructional module for undergraduate and graduate transportation-related courses for disciplines such as engineering, business, marketing, and technology. The concept of paratransit generally refers to modes of transportation other than mass transit and solo-driven automobiles. The…

  13. A novel Cs-(129)Xe atomic spin gyroscope with closed-loop Faraday modulation. (United States)

    Fang, Jiancheng; Wan, Shuangai; Qin, Jie; Zhang, Chen; Quan, Wei; Yuan, Heng; Dong, Haifeng


    We report a novel Cs-(129)Xe atomic spin gyroscope (ASG) with closed-loop Faraday modulation method. This ASG requires approximately 30 min to start-up and 110 °C to operate. A closed-loop Faraday modulation method for measurement of the optical rotation was used in this ASG. This method uses an additional Faraday modulator to suppress the laser intensity fluctuation and Faraday modulator thermal induced fluctuation. We theoretically and experimentally validate this method in the Cs-(129)Xe ASG and achieved a bias stability of approximately 3.25 °∕h.

  14. Preparation, characterization, and stereochemistry of binuclear vanadyl(IV) monomethyl- and dimethyltartrate(4-) complexes and the crystal structure of tetrasodium (. mu. -(+)-dimethyltartrato(4-))-(. mu. -(-)-dimethyltartrato(4-))-bis(oxovanadate(IV)) dodecahydrate

    Energy Technology Data Exchange (ETDEWEB)

    Hahs, S.K.; Ortega, R.B.; Tapscott, R.E.; Campana, C.F.; Morosin, B.


    The syntheses and characterizations (by ESR, IR, and electronic spectroscopies) of the sodium salts of the DL and DD (or LL) binuclear complexes of vanadyl(IV) with dimethyltartrate(4-), dmt, and with monomethyltartrate(4-), mmt, are described. Na/sub 4/((VO)/sub 22/((+)-dmt)((-)-dmt)) exists in two crystal forms - a blue dodecahydrate and a pink hexahydrate. An x-ray diffraction study of the former shows that the V-V distance (3.429 (3) A) of the binuclear anion is decreased relative to that of the unsubstituted tartrate(4-), tart, complex, as predicted from earlier ESR studies, and that this decrease is due in part to a dropping of the vanadium atom into the plane of the four coordinating equatorial oxygen atoms. A sixth oxygen atom is weakly coordinated (2.377 (3) A) trans to the vanadyl oxygen atom. A purple tetradecahydrate also obtained with racenic dmt contains a mixture of ((VO)/sub 2/ ((+)-dmt)/sub 2/)/sup 4 -/ and ((VO)/sub 2/((-)-dmt)/sub 2/)/sup 4 -/). The aqueous solution ligand-exchange reaction between the DD and LL complexes of this salt to give the more stable DL isomer is remarkably slow (several hours at room temperature). Stereoselective effects allow the production of mixed-ligand species containing two of the three ligands tart, dmt, and mmt, and potentiometric titrations indicate a decreasing stability of the DL isomer (relative to the DD and LL isomers) as methyl substitution increases.

  15. A transmission line phase stabilizer (United States)

    Lutes, G. F.


    To meet the phase stability requirements of certain experiments performed with the Deep Space Network, transmission lines carrying reference signals must be stabilized to reduce changes in their electrical length due to mechanical movement or changes in ambient temperature. A transmission line phase stabilizer being developed at JPL to perform this function is described.

  16. Note: sensitivity multiplication module for quartz crystal microbalance applications. (United States)

    Burda, Ioan; Silaghi, Andreea; Tunyagi, Arthur; Simon, Simion; Popescu, Octavian


    In this Note, a novel sensitivity multiplication module was added to classical quartz crystal microbalance (QCM). The purpose is to increase QCM frequency shift without changing nominal frequency of the quartz crystal resonator or nominal frequency value delivered to the frequency counter. Allan deviance measurement confirms that the multiplication of the frequency shift is limited by the quartz crystal loads with direct effect in quartz crystal quality factor and oscillator stability. An experimental implementation of this new sensitivity multiplication module that can increase up to six times the frequency shift of the QCM was experimentally investigated using different load conditions.

  17. Moral Hazard and Stability

    DEFF Research Database (Denmark)

    Tumennasan, Norovsambuu


    Economists perceive moral hazard as an undesirable problem because it undermines efficiency. Carefully designed contracts can mitigate the moral hazard problem, but this assumes that a team is already formed. This paper demonstrates that these contracts are sometimes the reason why teams do...... not form. Formally, we study the team formation problem in which the agents’ efforts are not verifiable and the size of teams does not exceed quota r . We show that if the team members cannot make transfers, then moral hazard affects stability positively in a large class of games. For example, a stable...

  18. Core stability and bicycling. (United States)

    Asplund, Chad; Ross, Michael


    Bicycling is a popular fitness activity in the United States and around the world. Because of the nature of the bicycling position, the neck and back are at risk for injury. One method to prevent these injuries is to ensure that the body's "core" is strong and stable. A strong and stable core also provides a platform to maximize power transfer, improving performance. Core exercises also may enhance recovery from intense bicycling efforts. Simple stability exercises can improve performance and may prevent injuries in bicyclists.

  19. Cosmic baldness and stability

    Energy Technology Data Exchange (ETDEWEB)

    Panchapakesan, N.; Lohiya, D.


    The stability of the de Sitter metric and the relevance of the initial state of a domain which approaches a de Sitter universe asymptotically are investigated analytically, adapting the one-dimensional wave equation with effective potential derived by Khanal and Panchapakesan (1981), for the perturbations of the de Sitter-Schwarzschild metric, to the de Sitter case. It is demonstrated that initial nonspherical perturbations do not increase exponentially with time but rather decay, the frozen modes exponentially and the backscattered perturbations of finite angular momentum l as t to the -(2l - l). It is concluded that the cosmic horizon is stable and has no hair. 14 references.


    Directory of Open Access Journals (Sweden)



    Full Text Available Fourteen lentil genotypes were tested for grain yield in Southeastern Anatolia ecological conditions, over our consecutive years to classify these cultivars for yield stability. Seed yield ranged from 1.903 t/ha to 1.367 t/ha. RM76, RM601 and RM152 showed regression coeffi cient above 1.00, but RM76 among these lines was consistently produced the highest yields. The unstable cultivars, RM601 and RM152 had the highest S2 values and high C.V. for grain yield.

  1. Sustainability, Stability, and Resilience

    Directory of Open Access Journals (Sweden)

    Don Ludwig


    Full Text Available The purpose of this essay is to define and refine the concepts of stability and resilience and to demonstrate their value in understanding the behavior of exploited systems. Some ecological systems display several possible stable states. They may also show a hysteresis effect in which, even after a long time, the state of the system may be partly determined by its history. The concept of resilience depends upon our objectives, the types of disturbances that we anticipate, control measures that are available, and the time scale of interest.

  2. Stability Landscape of Shell Buckling (United States)

    Virot, Emmanuel; Kreilos, Tobias; Schneider, Tobias M.; Rubinstein, Shmuel M.


    We measure the response of cylindrical shells to poking and identify a stability landscape, which fully characterizes the stability of perfect shells and imperfect ones in the case where a single defect dominates. We show that the landscape of stability is independent of the loading protocol and the poker geometry. Our results suggest that the complex stability of shells reduces to a low dimensional description. Tracking ridges and valleys of this landscape defines a natural phase-space coordinates for describing the stability of shells.

  3. Stiffness determination of the controlled wheel module of a two-axle vehicle

    Directory of Open Access Journals (Sweden)

    Belevtseva N.V.


    Full Text Available The conditions of a secure loss of stability of a two-axle wheel vehicle with absolutely hard steering have been found before. The analytically derived conditions of a secure stability loss in case of torsional stiffness are dependent on the relationship between the slipping resistance coefficients, the transverse clutch coefficients on the axes, and the torsional stiffness of the controlled wheel module. In this case, the trail distance is taken into account in the wheel module control system, the mass of the module being neglected. The approach suggested in the paper does take into account the mass of the controlled wheel module. The slipping forces are presented accurate to a cubic term of expansion in slipping angles. The torsional stiffness intervals have been found that provide a secure loss of stability of a two-axle wheel vehicle model. The intervals have been obtained on the basis of a bifurcation analysis of actual bifurcations of the stationary states in the vicinity of the rectilinear motion of the model. Diagrams that illustrate the fulfillment of secure stability loss conditions and allow using the results obtained in designing a wheel module are presented in the paper. The technique used is alternative to the well-known M. Bautin’s approach to determination of secure-insecure conditions in case of a divergent loss of stability.

  4. [Research on VOC concentration detection by photoelastic modulation infrared spectrum absorption method]. (United States)

    Hu, Miao; Wang, Tai-yong; Qiao, Zhi-feng; Geng, Bo; Xiao, Xin-hua


    In order to ensure high stability and strong anti-interference ability in static interference system for qualitative and quantitative analysis of gas, a static scans interference detection system was designed based on photoelastic modulation infrared spectrum absorption system. The system consists of infrared laser, polarizer, photoelastic modulator, polarization analyzer and CCD components. By photoelastic modulator the principal refractive index of optical crystal will change cyclically by the modulation signal, producing cyclical changes in the optical path difference. With the calculation of modulation phase variation, the authors can get the function of the crystal length, the modulation cycle, and the range of optical path difference. Based on phase delay value and the energy distribution of interference pattern, the authors got the formula for the corresponding interference light intensity. The experiment used ZnSe crystal as the photoelastic modulation crystal, the polarizer uses the DOP3212 polarizer, and the detector uses the TCD5390AP array CCD. The five groups have different concentrations with three common VOC gases (formaldehyde, benzene and xylene) for detecting the concentrations of gases. The experimental results with the traditional infrared absorption were compared with the test results of photoelastic modulation infrared spectrum absorption method. The method of photoelastic modulation infrared spectrum absorption had high stability and real-time features, while the detection accuracy is better than the traditional infrared absorption method.

  5. Printable luminescent down shifter for enhancing efficiency and stability of organic photovoltaics

    DEFF Research Database (Denmark)

    Kettle, J.; Bristow, N.; Gethin, D.T.


    , with a 51% enhancement in the measured stability (T75%). Significantly, the work provides clear experimental evidence that the LDS layer can act as a UV filter in OPVs without compromising the efficiency of the solar cell, thus providing an added benefit over commercial UV filters.......The proof of concept of using luminescent down shifting (LDS) layers as alternative UV filters for P3HT:PCBM OPVs is demonstrated using a lanthanide-based metal complex. The results are verified using a combination of indoor light soaking, with single cell devices, and outdoor performance...... half-life (T50%). The OPV modules were encapsulated and tested for outdoor stability over a 70 day period in the Negev desert, Israel. The modules made with the LDS filter are shown to match the stability of those made with a commercial UV filter and outperform the modules with no filter applied...

  6. Stability of the Levitron (United States)

    Heflinger, Lee O.; Ridgway, S. L.; Simon, Martin D.


    The Levitron, manufactured by Fascinations in Seattle WA, successfully demonstrates magnetic suspension. A 22 gram spinning magnetic dipole top is supported by magnetic forces that balance its weight about 3.2 cm above a magnetized base, and it will float about two minutes until its spin rate has declined to about 1000 rpm. However, since in general it is not possible (The Feynman Lectures on Physics Volume II, 5-4) to have a potential energy minimum or maximum for any rigidly connected system of poles in a magnetic field, the stability of the Levitron is not obvious. Gyroscopic forces that prevent the top from flipping over and being attracted to the base have been suggested as the source of the stability (US Patent 5,404,062, Hones et al.). We find that fixing the direction of the top axis in space is not sufficient. An analysis and numerical integration of the five degree of freedom equations of motion of the top that includes gyroscopic precession around the local magnetic field lines do predict that the top will be supported stably up to spin speeds of 2100 rpm.

  7. Genotype adaptability and stability

    Directory of Open Access Journals (Sweden)

    Dimitrijević Miodrag


    Full Text Available One of the primary concerns in breeding programs is a small genotype reaction to environmental factor variation for better usage of yield genetic potential. Particularly if one takes in consideration that yield could van greatly because of more and more variable meteorological conditions. Studies conducted to observe genotype and environmental relations relay on numerous mathematical models, but genotype behavior in various ecological conditions is not, still, precisely defined Major sources of variation influencing genotype behavior in different environments are genotype/environment interaction, genetic background and environmental conditions. These factors could play an important role in establishing growth regions for maximal realization of genotype genetic potential, as well as in selection of genotypes having better response to complex requirements of particular growth region. Stability, the genotype ability to perform high, uniform yield no meter of different environmental conditions, and adaptability, genotype ability to give uniform yield in a different environmental conditions, are two common terms used to define genotype reaction in a consequence of environmental changes. Most of the models dealing with stability and adaptability are based on variation sources appearing under the influence of treatment, multivariate effects and residue. No meter which statistical model is used for GE interaction estimation, there is an opinion that no solid proof for the existence of stable genotypes obtained in breeding programs, which make some space for further investigations. There are still questions to answer dealing with definitions, sources of variation, usage value of existent models and interpretation of the results. .

  8. Gender and family stability

    Directory of Open Access Journals (Sweden)


    Full Text Available The increasing trend of partnership disruption among families with children in recent decades has been accompanied by substantial changes in traditional gender roles in industrialized countries. Yet, relatively little is known about the effects of changing gender relations on family stability in the European context. In this paper, we study such gender influences at the familial and societal level in Sweden and Hungary between the mid-1960s and the early 1990s. We focus on the disruption of the first parental union (i.e. the union in which a couple's first child was born. Our analysis is based on data extracted from the Swedish and Hungarian Fertility and Family Surveys of 1992/93. We use the method of hazard regression. The results suggest (i that the establishment of the dual-earner family model influences family stability only if it is accompanied by some changes in traditional gender relations within the family, and (ii that women's and men's labor-market behavior have different effects in spite of the relatively long history of women's (also mothers' labor-force participation in both Sweden and Hungary.

  9. Polymer Thin Film Stabilization. (United States)

    Costa, A. C.; Oslanec, R.; Composto, R. J.; Vlcek, P.


    We study the dewetting dynamics of thin polystyrene (PS) films deposited on silicon oxide surfaces using optical (OM) and atomic force (AFM) microscopes. Quantitative analysis of the hole diameter as a function of annealing time at 175^oC shows that blending poly(styrene-block-methyl-methacrylate) (PS-b-PMMA) with PS acts to dramatically slow down the dewetting rate and even stops holes growth before they impinge. AFM studies show that the hole floor is smooth for a pure PS film but contains residual polymer for the blend. At 5% vol., a PS-b-PMMA with high molar mass and low PMMA is a more effective stabilizing agent than a low molar mass/high PMMA additive. The optimum copolymer concentration is 3% vol. beyond which film stability doesn't improve. Although dewetting is slowed down relative to pure PS, PS/PS-b-PMMA bilayers dewet at a faster rate than blends having the same overall additive concentration.

  10. Semiconductor lasers stability, instability and chaos

    CERN Document Server

    Ohtsubo, Junji


    This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in se...

  11. Modulating aging and longevity

    DEFF Research Database (Denmark)

    Rattan, Suresh

    Provides information and an evaluation of a variety of approaches tried for modulating aging and longevity, including dietary supplementation with antioxidants, vitamins and hormones, genetic engineering, life-style alterations, and hormesis through mild stress. After decades of systematic collec....... The goal of research on ageing is not to increase human longevity regardless of the consequences, but to increase active longevity free from disability and functional dependence......Provides information and an evaluation of a variety of approaches tried for modulating aging and longevity, including dietary supplementation with antioxidants, vitamins and hormones, genetic engineering, life-style alterations, and hormesis through mild stress. After decades of systematic...... collection of data describing age-related changes in organisms, organs, tissues, cells and macromolecules, biogerontologists are now in a position to construct general principles of ageing and explore various possibilities of intervention using rational approaches. While not giving serious consideration...

  12. Silicon Optical Modulator Simulation

    Directory of Open Access Journals (Sweden)

    Soon Thor LIM


    Full Text Available We developed a way of predicting and analyzing high speed optical modulator. Our research adopted a bottom-up approach to consider high-speed optical links using an eye diagram. Our method leverages on modular mapping of electrical characteristics to optical characteristics, while attaining the required accuracy necessary for device footprint approaching sub-micron scales where electrical data distribution varies drastically. We calculate for the bias dependent phase shift (2pi/mm and loss (dB/mm for the optical modulator based on the real and imaginary part of complex effective indices. Subsequently, combine effectively both the electrical and optical profiles to construct the optical eye diagram which is the essential gist of signal integrity of such devices.

  13. Lightweight Trauma Module - LTM (United States)

    Hatfield, Thomas


    Current patient movement items (PMI) supporting the military's Critical Care Air Transport Team (CCATT) mission as well as the Crew Health Care System for space (CHeCS) have significant limitations: size, weight, battery duration, and dated clinical technology. The LTM is a small, 20 lb., system integrating diagnostic and therapeutic clinical capabilities along with onboard data management, communication services and automated care algorithms to meet new Aeromedical Evacuation requirements. The Lightweight Trauma Module is an Impact Instrumentation, Inc. project with strong Industry, DoD, NASA, and Academia partnerships aimed at developing the next generation of smart and rugged critical care tools for hazardous environments ranging from the battlefield to space exploration. The LTM is a combination ventilator/critical care monitor/therapeutic system with integrated automatic control systems. Additional capabilities are provided with small external modules.

  14. Pulse code modulation telemetry - Properties of various binary modulation types (United States)

    Law, E. L.

    The present investigation is concerned with a comparison of the performance of methods for the transmission of digital data, taking into account aspects of performance under simulated range conditions. Attention is given to radio frequency spectra, bit error rate performance, peak carrier deviation, premodulation filtering, receiver IF bandpass filtering, receiver/demodulator video bandwidth, pulse code modulation (PCM) codes, phase shift keying, and four major methods for recording PCM signals. It is found that pulse code modulation/phase modulation (PCM/PM) signals can achieve better data quality than pulse code modulation/frequency modulation (PCM/FM) signals with the same radiated power if wide bandwidths are available.

  15. Sparx PCA Module

    Energy Technology Data Exchange (ETDEWEB)


    Sparx, a new environment for Cryo-EM image processing; Cryo-EM, Single particle reconstruction, principal component analysis; Hardware Req.: PC, MAC, Supercomputer, Mainframe, Multiplatform, Workstation. Software Req.: operating system is Unix; Compiler C++; type of files: source code, object library, executable modules, compilation instructions; sample problem input data. Location/transmission:; User manual & paper:;

  16. Chemical release module facility (United States)

    Reasoner, D. L.


    The chemical release module provides the capability to conduct: (1) thermite based metal vapor releases; (2) pressurized gas releases; (3) dispersed liquid releases; (4) shaped charge releases from ejected submodules; and (5) diagnostic measurements with pi supplied instruments. It also provides a basic R-F and electrical system for: (1) receiving and executing commands; (2) telemetering housekeeping data; (3) tracking; (4) monitoring housekeeping and control units; and (5) ultrasafe disarming and control monitoring.

  17. Solar-heating module (United States)

    Christensen, D. L.


    Comprehensive set of engineering drawings and instructions for installation, operation, repair, and maintenance are available for module that provides hot-air or hot-water needs for residence or commercial building. It can accommodate solar collectors of various sizes and types. It can provide utility, workshop, or storage space, in addition to providing hot water or hot air. Extensive insulation minimizes heat losses in structure and in storage and fluid-handling subsystems.

  18. Tandem resonator reflectance modulator (United States)

    Fritz, I.J.; Wendt, J.R.


    A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors. 8 figs.

  19. Synthetic Space Vector Modulation (United States)


    controller. The VSI controller has traditionally been operated by hardwired pulse-width modulation (PWM) or the use of a programmable microprocessor ...frequency. The primary difference between SVM and synthetic SVM is the implementation strategy of software versus inexpensive hardware, respectively. A...resistors and capacitors. There are no microcontrollers or FPGAs necessary to produce Alt-Rev SVM. F. DUAL OUTPUT VARIABLE FREQUENCY OSCILLATOR After

  20. Parallel phase modulation scheme for interferometric gravitational-wave detectors. (United States)

    Hartman, M T; Quetschke, V; Tanner, D B; Reitze, D H; Mueller, G


    Advanced LIGO (aLIGO) requires multiple frequency sidebands to disentangle all of the main interferometer's length signals. This paper presents the results of a risk reduction experiment to produce two sets of frequency sidebands in parallel, avoiding mixed 'sidebands on sidebands'. Two phase modulation frequencies are applied to separate Electro-Optic Modulators (EOMs), with one EOM in each of the two arms of a Mach-Zehnder interferometer. In this system the Mach-Zehnder's arm lengths are stabilized to reduce relative intensity noise in the recombined carrier beam by feeding a corrective control signal back to the Rubidium Titanyl Phosphate (RTP) EOM crystals to drive the optical path length difference to zero. This setup's use of the RTP crystals as length actuators provides enough bandwidth in the feedback to meet arm length stability requirements for aLIGO.

  1. Equivalence of quotient Hilbert modules

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    in principle may be used, to construct a set of complete unitary invariants for quotient modules Q = M ⊖ M0. The invariants are given explicitly in the particular case of k = 2. Keywords. Hilbert modules; function algebra; quotient module; longitudinal and transversal curvature; kernel function; jet and angle. 1. Preliminaries. Let.

  2. FERMI multi-chip module

    CERN Multimedia

    This FERMI multi-chip module contains five million transistors. 25 000 of these modules will handle the flood of information through parts of the ATLAS and CMS detectors at the LHC. To select interesting events for recording, crucial decisions are taken before the data leaves the detector. FERMI modules are being developed at CERN in partnership with European industry.

  3. Polarisation Encryption/Decryption Module

    DEFF Research Database (Denmark)


    A polarisation encryption/decryption module comprising at least two array based modulating devices, preferably spatial light modulators (SLMs), at least one array based intensity detector, and at least one source of electromagnetic radiation. A local region of information displayed on a first...

  4. The Stability of Chandra Telescope Pointing and Spacial Resolution (United States)

    Zhao, Ping


    Chandra X-ray Observatory revolutionized the X-ray astronomy as being the first, and so far the only, X-ray telescope achieving sub-arcsecond spacial resolution. Chandra is comprised of three principal elements: the High Resolution Mirror Assembly (HRMA), Pointing Control and Aspect Determination (PCAD) system, and the Science Instrument Module (SIM), which is where the X-ray detectors mounted and is connected to the HRMA by a 10-meter long Optical Bench Assembly. To achieve and retain the unprecedented imaging quality, it is critical that these three principal elements to stay rigid and stable for the entire life time of the Chandra operation. I will review the issues of telescope pointing stability, optical Axis, aimpoint and their impacts to the Chandra operation, and evaluate the integrity and stability of the telescope. I will show images taken from all four detectors since launch to demonstrate the quality and stability of the Chandra spacial resolution.

  5. A Robust Method to Improve Stability in Matrix Converters

    DEFF Research Database (Denmark)

    Liu, F.; Klumpner, Christian; Blaabjerg, Frede


    The last few years witness a high interest in the use of matrix converter technology in AC/AC power conversion. This paper is focusing on its stability issues. It analyzes the instability reason and reveals that the harmonics interaction of its input current and input voltage is the main cause...... of instability. The matrix converter stability can be improved by decoupling its input current with the input voltage. A modulation strategy is presented that satisfies the idea. The difference of the strategy compared with the traditional one only concerns on the definition of the reference angle for the input...... current vector. A matrix converter model that takes the switching behavior and effects related with the digital implementations into consideration is developed for evaluation of the strategy. The simulation results show that the proposed strategy can highly improve the matrix converter stability...

  6. Engineering Lipases: walking the fine line between activity and stability (United States)

    Dasetty, Siva; Blenner, Mark A.; Sarupria, Sapna


    Lipases are enzymes that hydrolyze lipids and have several industrial applications. There is a tremendous effort in engineering the activity, specificity and stability of lipases to render them functional in a variety of environmental conditions. In this review, we discuss the recent experimental and simulation studies focused on engineering lipases. Experimentally, mutagenesis studies have demonstrated that the activity, stability, and specificity of lipases can be modulated by mutations. It has been particularly challenging however, to elucidate the underlying mechanisms through which these mutations affect the lipase properties. We summarize results from experiments and molecular simulations highlighting the emerging picture to this end. We end the review with suggestions for future research which underscores the delicate balance of various facets in the lipase that affect their activity and stability necessitating the consideration of the enzyme as a network of interactions.

  7. Kinetics, products, and stereochemistry of the reaction of chlorine atoms with cis- and trans-2-butene in 10-700 Torr of N2 or N2/O2 diluent at 297 K. (United States)

    Kaiser, E W; Donahue, C J; Pala, I R; Wallington, T J; Hurley, M D


    The reactions of Cl atoms with cis- and trans-2-butene have been studied using FTIR and GC analyses. The rate constant of the reaction was measured using the relative rate technique. Rate constants for the cis and trans isomers are indistinguishable over the pressure range 10-900 Torr of N2 or air and agree well with previous measurements at 760 Torr. Product yields for the reaction of cis-2-butene with Cl in N2 at 700 Torr are meso-2,3-dichlorobutane (47%), DL-2,3-dichlorobutane (18%), 3-chloro-1-butene (13%), cis-1-chloro-2-butene (13%), trans-1-chloro-2-butene (2%), and trans-2-butene (8%). The yields of these products depend on the total pressure. For trans-2-butene, the product yields are as follows: meso-2,3-dichlorobutane (48%), dl-2,3-dichlorobutane (17%), 3-chloro-1-butene (12%), cis-1-chloro-2-butene (2%), trans-1-chloro-2-butene (16%), and cis-2-butene (2%). The products are formed via addition, addition-elimination from a chemically activated adduct, and abstraction reactions. These reactions form (1) the stabilized 3-chloro-2-butyl radical, (2) the chemically activated 3-chloro-2-butyl radical, and (3) the methylallyl radical. These radicals subsequently react with Cl2 to form the products via a proposed chemical mechanism, which is discussed herein. This is the first detailed study of stereochemical effects on the products of a gas-phase Cl+olefin reaction. FTIR spectra (0.25 cm(-1) resolution) of meso- and DL-2,3-dichlorobutane are presented. The relative rate technique was used (at 900 Torr and 297 K) to measure: k(Cl + 3-chloro-1-butene) = (2.1 +/- 0.4) x 10(-10), k(Cl + 1-chloro-2-butene) = (2.2 +/- 0.4) x 10(-10), and k(Cl + 2,3-dichlorobutane) = (1.1 +/- 0.2) x 10(-11) cm3 molecule(-1) s(-1).

  8. A ternary memory module using low-voltage control over optical properties of metal-polypyridyl monolayers. (United States)

    Kumar, Anup; Chhatwal, Megha; Mondal, Prakash Chandra; Singh, Vikram; Singh, Alok Kumar; Cristaldi, Domenico A; Gupta, Rinkoo D; Gulino, Antonino


    A ternary memory module has been designed as a function of precise voltage command. The monolayer based module displays perpetual stability and non-hysteretic reversibility for multiple scans (10(2)). Ternary-state readout provides a vision to integrate the next generation of "smart electro-optical devices" viable for multi-state memory.

  9. Scophony Spatial Light Modulator (United States)

    Johnson, Richard V.; Guerin, Jean-Michel; Swanberg, Mel E.


    An alternative to the conventional flying-spot scanner architecture is the Scophony scanner. The Scophony scanner uses the same optical elements as the more familiar flying-spot scanner: a rotating polygon mirror, an acousto-optic (A/O) modulator, and a laser light source. The flying-spot scanner is designed to construct its image a pixel at a time; no more than one pixel is illuminated at any given instant. The Scophony scanner is designed to image a broad swath of the A/0 modulator's acoustic pulses onto the photoreceptor. Many pixels are illuminated at any given instant in the Scophony scanner. The result is a scanner with a coherent imaging response. This coherent response implies that the phase of the modulator's electronic drive signal for a given pixel profoundly influences the formation of the neighboring pixels at the scanner image plane. This coherent response enables electronic manipulation of the video drive signal to have significant impact on the optical imaging performance of the scanner. In this paper, two electronic manipulation schemes are pro-posed for doubling the resolution of the Scophony scanner, one scheme for analog video signals and one scheme for binary digital video signals. Each scheme gives superior contrast ratio performance when compared with the flying-spot scanner.

  10. Solar Module Fabrication

    Directory of Open Access Journals (Sweden)

    A. El Amrani


    Full Text Available One of the most important steps in the photovoltaic industry is the encapsulation of the solar cells. It consists to connect the cells in order to provide useful power for any application and also protect them from environmental damages which cause corrosion, and mechanical shocks. In this paper, we present the encapsulation process we have developed at Silicon Technology Unit (UDTS for monocrystalline silicon solar cells. We will focus particularly on the thermal treatment, the most critical step in the process, which decides on the quality and the reliability of the module. This thermal treatment is conducted in two steps: the lamination and the polymerization. Several tests of EVA reticulation have been necessary for setting technological parameters such as the level of vacuum, the pressure, the temperature, and the time. The quality of our process has been confirmed by the tests conducted on our modules at the European Laboratory of Joint Research Centre (JRC of ISPRA (Italy. The electrical characterization of the modules has showed that after the encapsulation the current has been improved by a factor of 4% to 6% and the power gain by a factor of 4% to 7%. This is mainly due to the fact of using a treated glass, which reduces the reflection of the light at a level as low as 8%.

  11. Modulation masking produced by complex-tone modulators

    DEFF Research Database (Denmark)

    Ewert, Stephan; Verhey, J.L.; Dau, Torsten


    Thresholds were measured for detecting sinusoidal amplitude modulation in the presence of a complex-tone masker modulation. Both modulations were applied to the same sinusoidal carrier. Two different masker modulations were used: (i) a pair of components beating at the difference frequency and (ii......) a three-tone complex producing a sinusoidal amplitude modulation of the modulation depth at the difference frequency between adjacent components. Both maskers show a periodicity in the waveform that is not contained in the envelope spectrum itself but can be observed when the envelope of the envelope......, referred to as the "venelope" [Ewert et al., J. Acoust. Soc. Am. 112. 2921-2931 (2002)], is calculated. For a signal frequency equal to the masker-venelope periodicity, modulation depth at threshold was measured as a function of the signal phase relative to the phase of the masker-venelope component...

  12. Food Fortification Stability Study (United States)

    Sirmons, T.; Cooper, M.; Douglas, G.


    NASA has established the goal of traveling beyond low-Earth orbit and extending manned exploration to Mars. The length of proposed Mars missions and the lack of resupply missions increases the importance of nutritional content in the food system, which will need a five-year shelf life. The purpose of this research is to assess the stability of vitamin supplementation in traditionally processed spaceflight foods. It is expected that commercially available fortification nutrients will remain stable through a long duration exploration mission at sufficient levels if compatible formulation, processing, and storage temperatures are achieved. Five vitamins (vitamin E, vitamin K, pantothenic acid, folic acid, and thiamin) were blended into a vitamin premix (DSM, Freeport, TX) such that the vitamin concentration per serving equaled 25% of the recommended daily intake after two years of ambient storage. Four freeze-dried foods (Scrambled Eggs, Italian Vegetables, Potatoes Au Gratin, Noodles and Chicken) and four thermo-stabilized foods (Curry Sauce with Vegetables, Chicken Noodle Soup, Grilled Pork Chop, Rice with Butter) were produced, with and without the vitamin premix, to assess the impact of the added fortification on color and taste and to determine the stability of supplemental vitamins in spaceflight foods. The addition of fortification to spaceflight foods did not greatly alter the organoleptic properties of most products. In most cases, overall acceptability scores remained above 6.0 (minimum acceptable score) following six months and one year of low-temperature storage. Likewise, the color of fortified products appears to be preserved over one year of storage. The only exceptions were Grilled pork Chop and Chicken Noodle Soup whose individual components appeareddegrade rapidly over one year of storage. Finally, most vitamins appeared to be stable during long-term storage. The only exception was thiamin, which degraded rapidly during the first year of storage at

  13. Food Fortification Stability Study (United States)

    Abdulmalik, T. O.; Cooper, M. R.; Douglas, G. L.


    NASA has established the goal of traveling beyond low-Earth orbit and extending manned exploration to Mars. The extended length of a Mars mission, along with the lack of resupply missions increases the importance of nutritional content in the food system. The purpose of this research is to assess the stability of vitamin supplementation in traditionally processed spaceflight foods. It is expected that commercially available fortificants will remain stable through long-duration missions if proper formulation, processing, and storage temperatures are all achieved. Five vitamins (vitamin E, vitamin K, pantothenic acid, folic acid, and thiamin) were blended into a vitamin premix (DSM, Freeport, TX); premixes were formulated to be compatible with current processing techniques (retort or freeze-dried), varied water activities (high or low), and packaging material. The overall goal of this process is to provide 25% of the recommended daily intake of each vitamin (per serving), following processing and two years of ambient storage. Four freeze-dried foods (Scrambled Eggs, Italian Vegetables, Potatoes Au Gratin, Noodles and Chicken) and four thermostabilized foods (Curry Sauce with Vegetables, Chicken Noodle Soup, Grilled Pork Chop, Rice with Butter) were produced (with and without the vitamin premix), to assess the impact of the added fortificant on color and taste, and to determine the stability of supplemental vitamins in spaceflight foods. The use of fortification in spaceflight foods appears to be a plausible mitigation step to inadequate nutrition. This is due to the ease of vitamin addition as well as the sustainability of the premixes through initial processing steps. Postprocessing analysis indicated that vitamin fortification with this premix did not immediately impact organoleptic properties of the food. At this stage, the largest hurdle to fortification is the preciseness to which vitamins can be added; the total amount of vitamins required for production is 10

  14. Stability versus Optimality (United States)

    Inanloo, B.


    The Caspian Sea is considered to be the largest inland body of water in the world, which located between the Caucasus Mountains and Central Asia. The Caspian Sea has been a source of the most contentious international conflicts between five littoral states now borders the sea: Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The conflict over the legal status of this international body of water as an aftermath of the breakup of the Soviet Union in 1991. Since then the parties have been negotiating without coming up with any agreement neither on the ownerships of waters, nor the oil and natural gas beneath them. The number of involved stakeholders, the unusual characteristics of the Caspian Sea in considering it as a lake or a sea, and a large number of external parties are interested in the valuable resources of the Sea has made this conflict complex and unique. This paper intends to apply methods to find the best allocation schemes considering acceptability and stability of selected solution to share the Caspian Sea and its resources fairly and efficiently. Although, there are several allocation methods in solving such allocation problems, however, most of those seek a socially optimal solution that can satisfy majority of criteria or decision makers, while, in practice, especially in multi-nation problems, such solution may not be necessarily a stable solution and to be acceptable to all parties. Hence, there is need to apply a method that considers stability and acceptability of solutions to find a solution with high chance to be agreed upon that. Application of some distance-based methods in studying the Caspian Sea conflict provides some policy insights useful for finding solutions that can resolve the dispute. In this study, we use methods such as Goal Programming, Compromise Programming, and considering stability of solution the logic of Power Index is used to find a division rule that is stable negotiators. The results of this study shows that the

  15. Technical Specification for the CLIC Two-Beam Module

    CERN Document Server

    Riddone, G; Nousiainen, R; Samoshkin, A; Schulte, D; Syratchev, I; Wuensch, W; Zennaro, R


    A high-energy (0.5-3 TeV centre-of-mass), highluminosity Compact Linear Collider (CLIC) is being studied at CERN [1]. The CLIC main linacs, 21-km long each, are composed of 2-m long two beam modules. This paper presents their current layout, the main requirements for the different sub-systems (alignment, supporting, stabilization, cooling and vacuum) as well as the status of their integration.

  16. Receiver Gain Modulation Circuit (United States)

    Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen


    A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by

  17. Durable crystalline Si photovoltaic modules based on silicone-sheet encapsulants (United States)

    Hara, Kohjiro; Ohwada, Hiroto; Furihata, Tomoyoshi; Masuda, Atsushi


    Crystalline Si photovoltaic (PV) modules were fabricated with sheets of poly(dimethylsiloxane) (silicone) as an encapsulant. The long-term durability of the silicone-encapsulated PV modules was experimentally investigated. The silicone-based modules enhanced the long-term durability against potential-induced degradation (PID) and a damp-heat (DH) condition at 85 °C with 85% relative humidity (RH). In addition, we designed and fabricated substrate-type Si PV modules based on the silicone encapsulant and an Al-alloy plate as the substratum, which demonstrated high impact resistance and high incombustible performance. The high chemical stability, high volume resistivity, rubber-like elasticity, and incombustibility of the silicone encapsulant resulted in the high durability of the modules. Our results indicate that silicone is an attractive encapsulation material, as it improves the long-term durability of crystalline Si PV modules.

  18. Siemens solar CIS photovoltaic module and system performance at the National Renewable Energy Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Strand, T.; Kroposki, B.; Hansen, R. [National Renewable Energy Lab., Golden, CO (United States); Willett, D. [Siemens Solar Industries, Camarillo, CA (United States)


    This paper evaluates the individual module and array performance of Siemens Solar Industries copper indium diselenide (CIS) polycrystalline thin-film technology. This is accomplished by studying module and array performance over time. Preliminary temperature coefficients for maximum power, maximum-power voltage, maximum-power current, open-circuit voltage, short-circuit current, and fill factor are determined at both the module and array level. These coefficients are used to correct module/array performance to 25{degrees}C to evaluate stability. The authors show that CIS exhibits a strong inverse correlation between array power and back-of-module temperature. This is due mainly to the narrow bandgap of the CIS material, which results in a strong inverse correlation between voltage and temperature. They also show that the temperature-corrected module and array performance has been relatively stable over the evaluation interval ({approx}2 years).

  19. Stabilized fiber-optic Mach-Zehnder interferometer for carrier-frequency rejection. (United States)

    Cooper, Nathan; Woods, Jonathan; Bateman, James; Dunning, Alexander; Freegarde, Tim


    We have demonstrated stabilization of a fiber-optic Mach-Zehnder interferometer, with a centimeter-scale path difference, to the transmission minimum for the carrier wave of a frequency-modulated laser beam. A time-averaged extinction of 32 dB, limited by the bandwidth of the feedback, was maintained over several hours. The interferometer was used to remove the carrier wave from a 780 nm laser beam that had been phase modulated at 2.7 GHz.

  20. Stabilization of Gyrotron Frequency by PID Feedback Control on the Acceleration Voltage (United States)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Tatematsu, Y.; Yamaguchi, Y.; Matsuki, Y.; Fujiwara, T.


    The results of frequency stabilization by proportional-integral-derivative (PID) feedback control of acceleration voltage in the 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) are presented. The experiment was organized on the basis of the frequency modulation by modulation of acceleration voltage of beam electrons. The frequency stabilization during 10 h experiment was better than 10-6, which is compared with the results of the frequency deviation in free-running gyrotron operation.

  1. Entrepreneurship and Employment Stability

    DEFF Research Database (Denmark)

    Failla, Virgilio; Melillo, Francesca; Reichstein, Toke


    This paper challenges the conventional belief that entrepreneurship is an unstable career path. Using longitudinal matched employer–employee data from Denmark, the analysis reveals that a transition to entrepreneurship decreases individual's employment turnover tendency. Three explanations...... are identified and empirically explored: (i) job matching, (ii) labour market value, and (iii) personal commitment. Entrepreneurs appear to be more productive and thus better matched compared to wageworkers. However, they also appear to be locked in entrepreneurship because of their anticipated lower value...... in the labour market and because of their personal attachment to the venture. The counter-intuitive finding – entrepreneurship yields greater employment stability – only holds with respect to subsequent transitions to wagework and not for new venture founding. The results have implications for our understanding...

  2. From Crisis to Stability

    DEFF Research Database (Denmark)

    Ban, Cornel; Seabrooke, Leonard

    , but also access to documents regulation and accountability vis-à-vis the European Parliament, the Court of Auditors and Anti-Fraud Office. Transparency International EU’s in-depth study of the governance and accountability of the ESM provides the first comprehensive analysis of the newest European economic...... governance institution, and makes a number of concrete recommendations. To make the ESM accountable, more transparency is in order, about where decisions are taken and who calls the shots. Is it the ESM, the Eurogroup, the Commission, or a coalition of Member States? Our report launch attempts to answer......The European Stability Mechanism (ESM) was created to save the euro from collapse. But the Eurozone’s bailout fund is not actually an EU institution. This has a series of knock-on effects, making it difficult to hold the ESM to EU standards as regards transparency, legal review by the CJEU...

  3. Laser controlled flame stabilization (United States)

    Early, James W.; Thomas, Matthew E.


    A method and apparatus is provided for initiating and stabilizing fuel combustion in applications such as gas turbine electrical power generating engines and jet turbine engines where it is desired to burn lean fuel/air mixtures which produce lower amounts of NO.sub.x. A laser induced spark is propagated at a distance from the fuel nozzle with the laser ignitor being remotely located from the high temperature environment of the combustion chamber. A laser initiating spark generated by focusing high peak power laser light to a sufficiently tight laser spot within the fuel to cause the ionization of air and fuel into a plasma is unobtrusive to the flow dynamics of the combustion chamber of a fuel injector, thereby facilitating whatever advantage can be taken of flow dynamics in the design of the fuel injector.

  4. Complementarity and stability conditions

    Directory of Open Access Journals (Sweden)

    Howard Georgi


    Full Text Available We discuss the issue of complementarity between the confining phase and the Higgs phase for gauge theories in which there are no light particles below the scale of confinement or spontaneous symmetry breaking. We show with a number of examples that even though the low energy effective theories are the same (and trivial, discontinuous changes in the structure of heavy stable particles can signal a phase transition and thus we can sometimes argue that two phases which have different structures of heavy particles that cannot be continuously connected and thus the phases cannot be complementary. We discuss what this means and suggest that such “stability conditions” can be a useful physical check for complementarity.


    Energy Technology Data Exchange (ETDEWEB)

    M.A. Ebadian, Ph.D.


    Many U.S. Department of Energy (DOE) remediation sites have performed roof repair and roof replacement to stabilize facilities prior to performing deactivation and decommissioning (D&D) activities. This project will review the decision criteria used by these DOE sites, along with the type of repair system used for each different roof type. Based on this information, along with that compiled from roofing experts, a decision-making tool will be generated to aid in selecting the proper roof repair systems. Where appropriate, innovative technologies will be reviewed and applied to the decision-making tool to determine their applicability. Based on the results, applied research and development will be conducted to develop a method to repair these existing roofing systems, while providing protection for the D and D worker in a cost-efficient manner.

  6. Stabilities of generalized entropies

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Sumiyoshi [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Kaniadakis, G [Dipartimento di Fisica and Istituto Nazionale di Fisica della Materia (INFM), Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy); Scarfone, A M [Dipartimento di Fisica and Istituto Nazionale di Fisica della Materia (INFM), Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy)


    The generalized entropic measure, which is maximized by a given arbitrary distribution under the constraints on normalization of the distribution and the finite ordinary expectation value of a physical random quantity, is considered. To examine if it can be of physical relevance, its experimental robustness is discussed. In particular, Lesche's criterion is analysed, which states that an entropic measure is stable if its change under an arbitrary weak deformation of the distribution (representing fluctuations of experimental data) remains small. It is essential to note the difference between this criterion and thermodynamic stability. A general condition, under which the generalized entropy becomes stable, is derived. Examples known in the literature, including the entropy for the stretched-exponential distribution, the quantum-group entropy and the {kappa}-entropy are discussed.

  7. Microwave modulation characteristics of twisted liquid crystals with chiral dopant

    Directory of Open Access Journals (Sweden)

    Rui Yuan


    Full Text Available Adding a chiral dopant in twisted nematic (TN liquid crystal cell can stabilize the orientation of liquid crystal molecules, particularly in high TN (HTN or super TN (STN liquid crystal cells. The difference in pitches in liquid crystal is induced by the chiral dopant, and these different pitches affect the orientation of liquid crystal director under an external applied voltage and influence the characteristics of microwave modulation. To illustrate this point, the microwave phase shift per unit length (MPSL versus voltage is calculated on the basis of the elastic theory of liquid crystal and the finite-difference iterative method. Enhancing the pitch induced by the chiral dopant in liquid crystal increases the MPSLs, but the stability of the twisted structures is decreased. Thus, appropriate pitches of 100d, 4d, and 2d can be applied in TN, HTN, and STN cells with cell gap d to enhance the characteristics of microwave modulation and stabilize the structures in twisted cell. This method can improve the characteristics of liquid crystal microwave modulators such that the operating voltage and the size of such phase shifters can be decreased.

  8. Laser frequency stabilization using bichromatic crossover spectroscopy (United States)

    Jeong, Taek; Seb Moon, Han


    We propose a Doppler-free spectroscopic method named bichromatic crossover spectroscopy (BCS), which we then use for the frequency stabilization of an off-resonant frequency that does not correspond to an atomic transition. The observed BCS in the 5S1/2 → 5P1/2 transition of 87Rb is related to the hyperfine structure of the conventional saturated absorption spectrum of this transition. Furthermore, the Doppler-free BCS is numerically calculated by considering all of the degenerate magnetic sublevels of the 5S1/2 → 5P1/2 transition in an atomic vapor cell, and is found to be in good agreement with the experimental results. Finally, we successfully achieve modulation-free off-resonant locking at the center frequency between the two 5S1/2(F = 1 and 2) → 5P1/2(F' = 1) transitions using a polarization rotation of the BCS. The laser frequency stability was estimated to be the Allan variance of 2.1 × 10-10 at 1 s.

  9. Stability Analysis of Hybrid ALOHA

    Directory of Open Access Journals (Sweden)

    Wang Huahui


    Full Text Available We perform stability analysis of a recently proposed MAC protocol, hybrid ALOHA, based on the multipacket reception (MPR model. Hybrid ALOHA distinguishes from conventional slotted ALOHA by allowing conditional collision-free channel estimation and simultaneous transmissions, and hence improves the MPR capability of the system. The stability analysis of the two-user case ( has been conducted in our previous work. In this paper, we study the stability region of hybrid ALOHA for the general N-user ( system. By using the method of stochastic dominance and mathematical induction, we obtain the sufficient condition for the stability of hybrid ALOHA. As an illustration, we characterize the stability inner bounds for the case. In this particular situation, the results are derived by solving a nonhomogeneous Riemann-Hilbert problem. Potentially, the mathematical tools used in this paper can be exploited for obtaining closed-form results in stability analysis of wireless networks.

  10. Stability and Reactivity of Cyclometallated Naphthylamine Complexes in Pd-C Bond Insertion Reactions with Coordinated Alkynylphosphanes

    KAUST Repository

    Chen, Shuli


    Phenylbis(phenylethynyl)phosphane PhP(C≡CPh)2 coordinates regiospecifically to the α-methyl-chiral ortho-platinated and -palladated naphthylamine units at the positions trans to the nitrogen donors. The P→Pt coordination bond is kinetically inert, whereas the P→Pd bond is labile. Upon heating of these phosphane complexes at 70 °C, one of the C≡C bonds in the coordinated PhP(C≡CPh)2 was activated towards an intermolecular Pd-C bond insertion reaction with an external ortho-palladated naphthylamine ring. No intramolecular insertion reaction occurred. In contrast to its palladium analogue, the ortho-platinated ring is not reactive towards coordinated PhP(C≡CPh)2, although it can promote the Pd-C bond insertion reaction. However, despite the high kinetic stability of the P→Pt coordination, the organoplatinum unit is a noticeably weaker activator than its organopalladium counterpart. The chirality of the reacting ortho-metallated naphthylamine ligand exhibited high stereochemical influence on the formation of the new stereogenic phosphorus center during the course of these C-C bond-formation reactions. The coordination chemistry and the absolute stereochemistry of the dimetallic products were determined by single-crystal X-ray crystallographic analysis. The asymmetric monoinsertion of PhP(C≡CPh)2 coordinated to a cyclometallated N,N-dimethyl naphthyl/benzylamine template into the Pd-C bonds of N,N-dimethylnaphthylamine palladacycles has been demonstrated for the synthesis of a variety of new P-stereogenic homo- or heterodimetallic complexes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. New test and characterization methods for PV modules and cells

    Energy Technology Data Exchange (ETDEWEB)

    Van Aken, B.; Sommeling, P. [ECN Solar Energy, Petten (Netherlands); Scholten, H. [Solland, Heerlen (Netherlands); Muller, J. [Moser-Baer, Eindhoven (Netherlands); Grossiord, N. [Holst Centre, Eindhoven (Netherlands); Smits, C.; Blanco Mantecon, M. [Holland Innovative, Eindhoven (Netherlands); Verheijen, M.; Van Berkum, J. [Philips Innovation Services, Eindhoven (Netherlands)


    The results of the project geZONd (shared facility for solar module analysis and reliability testing) are described. The project was set up by Philips, ECN, Holst, Solland, OM and T and Holland Innovative. The partners have shared most of their testing and analysis equipment for PV modules and cells, and together developed new or improved methods (including the necessary application know-how). This enables faster and more efficient innovation projects for each partner, and via commercial exploitation for other interested parties. The project has concentrated on five failure modes: corrosion, delamination, moisture ingress, UV irradiation, and mechanical bending. Test samples represented all main PV technologies: wafer based PV and rigid and flexible thin-film PV. Breakthroughs are in very early detection of corrosion, in quantitative characterization of adhesion, in-situ detection of humidity and oxygen inside modules, and ultra-fast screening of materials on UV stability.

  12. Monolithic amorphous silicon modules on continuous polymer substrate

    Energy Technology Data Exchange (ETDEWEB)

    Grimmer, D.P. (Iowa Thin Film Technologies, Inc., Ames, IA (United States))


    This report examines manufacturing monolithic amorphous silicon modules on a continuous polymer substrate. Module production costs can be reduced by increasing module performance, expanding production, and improving and modifying production processes. Material costs can be reduced by developing processes that use a 1-mil polyimide substrate and multilayers of low-cost material for the front encapsulant. Research to speed up a-Si and ZnO deposition rates is needed to improve throughputs. To keep throughput rates compatible with depositions, multibeam fiber optic delivery systems for laser scribing can be used. However, mechanical scribing systems promise even higher throughputs. Tandem cells and production experience can increase device efficiency and stability. Two alternative manufacturing processes are described: (1) wet etching and sheet handling and (2) wet etching and roll-to-roll fabrication.

  13. On staggered indecomposable Virasoro modules

    Energy Technology Data Exchange (ETDEWEB)

    Kytoelae, Kalle [Geneve Univ. (Switzerland); Ridout, David [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)


    In this article, certain indecomposable Virasoro modules are studied. Specifically, the Virasoro mode L0 is assumed to be non-diagonalisable, possessing Jordan blocks of rank two. Moreover, the module is further assumed to have a highest weight submodule, the ''left module'', and that the quotient by this submodule yields another highest weight module, the ''right module''. Such modules, which have been called staggered, have appeared repeatedly in the logarithmic conformal field theory literature, but their theory has not been explored in full generality. Here, such a theory is developed for the Virasoro algebra using rather elementary techniques. The focus centres on two different but related questions typically encountered in practical studies: How can one identify a given staggered module, and how can one demonstrate the existence of a proposed staggered module. Given just the values of the highest weights of the left and right modules, themselves subject to simple necessary conditions, invariants are defined which together with the knowledge of the left and right modules uniquely identify a staggered module. The possible values of these invariants form a vector space of dimension zero, one or two, and the structures of the left and right modules limit the isomorphism classes of the corresponding staggered modules to an affine subspace (possibly empty). The number of invariants and affine restrictions is purely determined by the structures of the left and right modules. Moreover, in order to facilitate applications, the expressions for the invariants and restrictions are given by formulae as explicit as possible (they generally rely on expressions for Virasoro singular vectors). Finally, the text is liberally peppered throughout with examples illustrating the general concepts. These have been carefully chosen for their physical relevance or for the novel features they exhibit. (orig.)

  14. Design and operating experience of a 40 MW, highly-stabilized power supply

    Energy Technology Data Exchange (ETDEWEB)

    Boenig, H.J. [Los Alamos National Lab., NM (United States); Ferner, J.A. [Florida State Univ., Tallahassee, FL (United States). Nationa High Magnetic Field Laboratory; Bogdan, F.; Morris, G.C. [ABB Industrial Systems, New Berlin, WI (United States); Rumrill, R.S. [Alpha Scientific Electronics Inc., Hayward, CA (United States)


    Four 10 MW, highly-stabilized power supply modules have been installed at the National High Magnetic Field Laboratory in Tallahassee, FL, to energize water-cooled, resistive, high-field research magnets. The power supply modules achieve a long term current stability if 10 ppM over a 12 h period with a short term ripple and noise variation of <10 ppM over a time period of one cycle. The power supply modules can operate independently, feeding four separate magnets, or two, three or four modules can operate in parallel. Each power supply module consists of a 12.5 kV vacuum circuit breaker, two three-winding, step-down transformers, a 24-pulse rectifier with interphase reactors, and a passive and an active filter. Two different transformer tap settings allow rated dc supply output voltages of 400 and 500 V. The rated current of a supply module is 17 kA and each supply module has a one-hour overload capability of 20 kA. The isolated output terminals of each power supply module are connected to a reversing switch. An extensive high-current bus system allows the modules to be connected to 16 magnet cells. This paper presents the detailed design of the power supply components. Various test results taken during the commissioning phase with a 10 MW resistive load and results taken with the research magnets are shown. The effects of the modules on the electrical supply system and the operational behavior of the power factor correction/harmonic filters are described. Included also are results of a power supply module feeding a superconducting magnet during quench propagation tests. Problems with the power supply design and solutions are presented. Some suggestions on how to improve the performance of these supplies are outlined.

  15. Self Defense Module


    Shibi k john


    Self Defense module is like a Smart Watch For Women .It has the potential to help women with technologies that are embedded. It is specially designed for women safety. It has a control button that will be used by women to inform nearby police when they are in danger. This watch directly gets connected to the satellite through GPS when activated. Then the location is transferred through the GSM and it is also provided with a system that produces 60 shockwaves in 1 second in emergency situations.

  16. CDC 7600 Module

    CERN Multimedia


    The CDC 7600 has been created by Seymour Cray. It was designed to be compatible with the 6600, which allows for a substantial increase in performance. Furthermore the rise of new technologies has enabled this performance by reducing the minor cycle clock period from 100 ns to 27.5 ns (4 time faster). A very large machine, the 7600 had over 120 miles of hand-wired interconnections. It was the most powerful computer of its time. However, this speed caused a ground-loop problem causing intermittent faults, and eventually requiring all modules to be fitted with sheathed rubber bands. The CDC 7600 was replaced in 1983 by CRAY-1A.

  17. Module of solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Katsuaki; Ohira, Takeo


    It is proposed to apply transparent plastics film on the surface of solar cell module as the substitute of the transparent tempered glass. However, weather proof film made of polyester or polyvinyliden fluoride has a drawback of weak bonding with the filler made of ethylen-vinyl acetate copolymer. This invention relates to the improvement of the bonding characteristics without decreasing the transparency of the film, by covering the surface of it with Al or other metals, or inorganic material such as silicon dioxide, by applying sputtering or vapour deposition method. In addition, application of silan coupling agent is mentioned as an improving method of the bonding. (2 figs)

  18. HACT Spatial Light Modulator (United States)


    OSA Topical Conference on Spatial Light Modulators, September 10-12,1990). [20] WJ. Tanski, S.W. Merritt, R.N. Sacks, D.E. Cullen, EJ. Branciforte , R.D...Cullen, T.W. Grudkowski, S.W. Merritt, WJ. Tanski, R.D. Carroll, R.N. Sacks 3 and E.J. Branciforte , "HACT Device Applications", IEEE Ultrasonics...T. Eschrich, G. Peterson, r excitonic electroabsorption in coupled wells. R. Sacks, W. Tanski, and E. Branciforte is gratefully is attributed to an

  19. Semiconductor Spatial Light Modulators. (United States)


    68 29 Experimental time-expansion of modulated C02 laser beam for three levels of punp energies. CalcJlaten time-aependent solution is super... Gallium -Arsenide sample. Tre photo-excited carriers decay i Ga~s in a shorter distance because of their lower diffusion lengths as co’,nared to InSb...electron populations and producing large changes in te Far3day Dotation of another beam tined to a frequency close to tie absorption line. It has been shown

  20. Vaccination to Modulate Atherosclerosis (United States)

    Kimura, Takayuki; Tse, Kevin; Sette, Alessandro; Ley, Klaus


    Atherosclerosis is a chronic inflammatory disease of the artery wall. Adaptive immunity plays a key role in the pathogenesis of atherosclerosis. Recently, modulation of the immune response against atherosclerotic plaque antigen(s) has attracted attention as a potentially preventive and therapeutic approach. Here we review a series of studies on immunization with various antigens targeting treatment and prevention of atherosclerosis. Atherosclerosis-related antigens include oxidized LDL, apolipoprotein B-100, and heat shock protein 60/65. Accumulating evidence supports the idea that immunization with these antigenic proteins or peptides may reduce atherosclerosis. In this review, we discuss the current status of immunization studies and possible associated mechanisms of atheroprotection. PMID:25683179

  1. Towards predicting the stability of protein-stabilized emulsions

    NARCIS (Netherlands)

    Delahaije, R.J.B.M.; Gruppen, H.; Giuseppin, M.L.F.; Wierenga, P.A.


    The protein concentration is known to determine the stability against coalescence during formation of emulsions. Recently, it was observed that the protein concentration also influences the stability of formed emulsions against flocculation as a result of changes in the ionic strength. In both

  2. Processing module operating methods, processing modules, and communications systems (United States)

    McCown, Steven Harvey; Derr, Kurt W.; Moore, Troy


    A processing module operating method includes using a processing module physically connected to a wireless communications device, requesting that the wireless communications device retrieve encrypted code from a web site and receiving the encrypted code from the wireless communications device. The wireless communications device is unable to decrypt the encrypted code. The method further includes using the processing module, decrypting the encrypted code, executing the decrypted code, and preventing the wireless communications device from accessing the decrypted code. Another processing module operating method includes using a processing module physically connected to a host device, executing an application within the processing module, allowing the application to exchange user interaction data communicated using a user interface of the host device with the host device, and allowing the application to use the host device as a communications device for exchanging information with a remote device distinct from the host device.

  3. Selective Glucocorticoid Receptor modulators. (United States)

    De Bosscher, Karolien


    The ancient two-faced Roman god Janus is often used as a metaphor to describe the characteristics of the Glucocorticoid Receptor (NR3C1), which exhibits both a beneficial side, that serves to halt inflammation, and a detrimental side responsible for undesirable effects. However, recent developments suggest that the Glucocorticoid Receptor has many more faces with the potential to express a range of different functionalities, depending on factors that include the tissue type, ligand type, receptor variants, cofactor surroundings and target gene promoters. This behavior of the receptor has made the development of safer ligands, that trigger the expression program of only a desirable subset of genes, a real challenge. Thus more knowledge-based fundamental research is needed to ensure the design and development of selective Glucocorticoid Receptor modulators capable of reaching the clinic. Recent advances in the characterization of novel selective Glucocorticoid Receptor modulators, specifically in the context of anti-inflammatory strategies, will be described in this review. 2010 Elsevier Ltd. All rights reserved.

  4. Emissivity modulating electrochromic device (United States)

    Demiryont, Hulya; Shannon, Kenneth C., III; Sheets, Judd


    The IR-ECDTM (Infra-Red ElectroChromic Device) variable emitance device (VED) is an all-solid-state monolithic vacuum deposited thin film system with a unique metamaterial IR transparent-electrode system which functions as an electrically controlled dimmable mirror in the IR region. The maximum reflectance corresponding to the bleached condition of the system is around 90% (low-e condition, e=0.1). The minimum reflectance reaches nearly zero in the colored condition of the system (high emittance, e=1). The average emissivity modulation of the IRECDTM is 0.7 in the 8-12 micron region, and at 9.7 micron (room temperature) it reaches a value of 0.9. Half and full emissivity modulations occur within 2 and10 minutes respectively. Because of its light weight (5g/m2), low voltage requirement (+/- 1 Volts), extremely good emissivity control properties (from 0 to 0.9 at 300K) and highly repeatable deposition process, the IR-ECDTM technology is very attractive for satellite thermal control applications. The IR-ECDTM has been under evaluation in a real space environment since March 8, 2007. This paper presents recent achievements of the IR-ECDTM including space test results.

  5. Time transfer capability of standard small form factor pluggable laser modules based on photon counting approach (United States)

    Trojanek, Pavel; Prochazka, Ivan; Blazej, Josef


    We are reporting on timing parameters of commonly used standard Small Form Factor Pluggable (SFP) laser modules using single photon counting method. Photon counting is a promising approach for laser time transfer via optical fiber communication hardware. The sub-picosecond precision and stability may be achieved. We have performed several experiments with the aim to measure main parameters of the modules, such as time delay precision, time stability and temperature stability, all being critical for optical time transfer applications. Two standard 16 and 10 Gbit/s at 850 nm SFP modules were examined. The ultimate precision of possible time transfer of 800 fs for averaging times of hours was achieved. The modules together with their driving circuits exhibited very good temperature stability. The temperature drift as low as 300+/-200 fs/K was measured. The achieved timing parameters will enable to use the standard SFP modules for a new method of two way time transfer where the time differences between two distant time scales are measured in parallel to data transfer on existing optical data links without any communication interference.

  6. Whole Module Offgas Test Report: Space-Xl Dragon Module (United States)

    James, John T.


    On September 26 and September 28,2012 a chemist from the JSC Toxicology Group acquired samples of air in 500 m1 evacuated canisters from the sealed Space-Xl Dragon Module. One sample was also acquired from Space-X Facility near the module at the start of the test. Samples of the module air were taken in triplicate once the module had been sealed, and then taken again in triplicate 1.98 days later. Ofthe triplicate samples, the first served as a line purge, and the last two were analyzed. The results of 5 samples are reported.

  7. Reamer-stabilizer

    Energy Technology Data Exchange (ETDEWEB)

    Allison, G.L.


    A roller reamer-stabilizer tool includes a tubular body having threaded pin and box connectors at each end adapted to be connected in a drill string and providing a fluid passage connecting the upper part of the drill string with the lower part. Rollers having integral pins at their ends are mounted in pockets in the sides of the body. The pins are journaled in holes in arcuate cross section bearing blocks received in correlative sockets in the body at the ends of the pockets. The blocks make an interference fit with the body. Release bar access passages allow a release bar to be inserted behind each block to drive, wedge or pry it out. The holes in the blocks extend only part way through the blocks, the hole in the block at one end of each roller being blind, and the wall at the end of the hole in the block at the other end of each roller being ported. Each bearing is sealed by an O ring at the mouth or open end of the hole in the block. An additional O ring is provided adjacent the end wall of the ported block. Grease is stored in a bore extending axially in each roller through the pins at each end. Radial ports in the pins communicate the bore with the bearings. A flexible elastomeric boot closes the bore at the end of each roller received in the respective ported block, the port subjecting the interior of the boot to drilling fluid pressure.

  8. Spray combustion stability (United States)

    Liang, Pak-Yan; Jeng, S. M.; Litchford, Ronald


    The central purpose of this project is the improvement of liquid-fueled rocket motor design technology in order to assist the establishment of economical commercial access to space through the development of engines with enhanced performance and reliability. Specific research effort in the project is focused on spray physics and associated combustion instability phenomena. Results garnered from this work will contribute to the development of new computational tools for design of stable liquid propellant rocket engines. The specific objectives of the research effort include identifying and evaluating physical submodels which pertain to spray combustion stability with the idea of enhancing or refining existing submodels with a more comprehensive approach. In particular, any refinements to the spray combustion physical submodels which are achieved during the project will be channeled back to Rocketdyne for incorporation in their ARICC liquid rocket combustor code as second generation improvements. Also, as the ARICC code forms the basis or future CFD development, some effort is devoted to an evaluation of the code's capability for modeling oscillating pressure waves within the combustor.

  9. Stability and Change

    Directory of Open Access Journals (Sweden)

    April K. Clark


    Full Text Available Ever since Stouffer began to measure political tolerance a half century ago, multiple studies have shown that a number of social, psychological, and political characteristics play a significant role in influencing whether individuals want to extend civil liberties to fringe groups. However, less is known about the stability of tolerance attitudes over an individual’s lifetime. To address this problem, our research draws on a national U.S. multiple-generation, four-wave panel study stretching from 1965 to 1997. The intuitive appeal of the approach used in this study is to advance theoretical accounts for variations in political intolerance irrespective of generational placement, life cycle, and differences in the political context. Specifically, the panel design encourages an effort to examine the relative impact of the social, political, and psychological predictors on intolerance over time and across the same individuals, and to assess the consequences of how changes in these determinants affect some of our most fundamental hypotheses about the origins of these attitudes.

  10. Spectroscopic and electrochemical properties of organic framework of macrocylic OONNOO-donor ligand with its metal organic framework: Host/guest stability measurements (United States)

    Kumar, Rajiv; Singh, R. P.; Singh, R. P.


    In this study, we synthesized 1,2-di( o-aminophenoxy)ethane, as the starting material, used in the preparation of a novel hexadentate OONNOO-donor macrocyclic ligand-1,4,11,14-tetraoxo-7,8-diaza-5,6:9,10;15,16:19,20-terabezocyclododeca-8,17-iene. It has twenty membered organic framework (OF), which has been designed, synthesized and characterized. Our main findings of this paper are related to the organic framework of ligand, its capacity to digest the metal ions and the stability of metal organic framework (MOFs) with cobalt(II), nickel(II) and manganese(II). The authenticity of the used organic framework and its metal complexes have been detected and observed in solid state as well as in aqueous solutions. The main observations were made on the basis of physiochemical measurements viz.: elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, 1H NMR, 13C NMR, mass spectroscopy, electronic, ESR spectroscopy. In addition, the magnetic susceptibility and electrochemistry measurements have been made. The 1H NMR spectra suggest stereochemistry and proton movement interaction. Considering the used organic framework there are a lot of carbon atoms in the molecule reflected by the 13C NMR spectrum. All these observations gave a clear view to confirming the encapsulation; arrive at the composition, structure and geometry of encapsulated complexes. In simple words, it confirms the host/guest coordination and its stability. Electrochemical properties of the complexes have been investigated to confirm the various changes in oxidation state of metals with change in potentials with respect to current at different scan rate.

  11. Spectroscopic and electrochemical properties of organic framework of macrocylic OONNOO-donor ligand with its metal organic framework: host/guest stability measurements. (United States)

    Kumar, Rajiv; Singh, R P; Singh, R P


    In this study, we synthesized 1,2-di(o-aminophenoxy)ethane, as the starting material, used in the preparation of a novel hexadentate OONNOO-donor macrocyclic ligand-1,4,11,14-tetraoxo-7,8-diaza-5,6:9,10;15,16:19,20-terabezocyclododeca-8,17-iene. It has twenty membered organic framework (OF), which has been designed, synthesized and characterized. Our main findings of this paper are related to the organic framework of ligand, its capacity to digest the metal ions and the stability of metal organic framework (MOFs) with cobalt(II), nickel(II) and manganese(II). The authenticity of the used organic framework and its metal complexes have been detected and observed in solid state as well as in aqueous solutions. The main observations were made on the basis of physiochemical measurements viz.: elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, 1H NMR, 13C NMR, mass spectroscopy, electronic, ESR spectroscopy. In addition, the magnetic susceptibility and electrochemistry measurements have been made. The 1H NMR spectra suggest stereochemistry and proton movement interaction. Considering the used organic framework there are a lot of carbon atoms in the molecule reflected by the 13C NMR spectrum. All these observations gave a clear view to confirming the encapsulation; arrive at the composition, structure and geometry of encapsulated complexes. In simple words, it confirms the host/guest coordination and its stability. Electrochemical properties of the complexes have been investigated to confirm the various changes in oxidation state of metals with change in potentials with respect to current at different scan rate.

  12. Metal stabilization of collagen and de novo designed mimetic peptides (United States)

    Parmar, Avanish S.; Xu, Fei; Pike, Douglas H.; Belure, Sandeep V.; Hasan, Nida F.; Drzewiecki, Kathryn E.; Shreiber, David I.; Nanda, Vikas


    We explore the design of metal binding sites to modulate triple-helix stability of collagen and collagen-mimetic peptides. Globular proteins commonly utilize metals to connect tertiary structural elements that are well separated in sequence, constraining structure and enhancing stability. It is more challenging to engineer structural metals into fibrous protein scaffolds, which lack the extensive tertiary contacts seen in globular proteins. In the collagen triple helix, the structural adjacency of the carboxy-termini of the three chains makes this region an attractive target for introducing metal binding sites. We engineered His3 sites based on structural modeling constraints into a series of designed homotrimeric and heterotrimeric peptides, assessing the capacity of metal binding to improve stability and in the case of heterotrimers, affect specificity of assembly. Notable enhancements in stability for both homo and heteromeric systems were observed upon addition of zinc(II) and several other metal ions only when all three histidine ligands were present. Metal binding affinities were consistent with the expected Irving-Williams series for imidazole. Unlike other metals tested, copper(II) also bound to peptides lacking histidine ligands. Acetylation of the peptide N-termini prevented copper binding, indicating proline backbone amide metal-coordination at this site. Copper similarly stabilized animal extracted Type I collagen in a metal specific fashion, highlighting the potential importance of metal homeostasis within the extracellular matrix. PMID:26225466

  13. Improving the stability of coal slurries: Final report. [Polygalacturonic acid and gum tragacanth

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.


    Polysaccharides were found to stabilize colloidal dispersions (such as coal particles and polystyrene latex particles) even at high ionic strengths. The stability studies with various kinds of polysaccharides showed that rod-like molecules (such as poly (galacturonic acid) and gum tragacanth) are much more effective stabilizers than highly-branched molecules such as arabinogalactan. This effective stabilization with the rod-like molecules was found to result from the adsorption of polysaccharides on the particles, i.e., the steric stabilization mechanism. The stability depends significantly on the solution pH, the molecular weight and the surface charge of particles. Adsorption isotherms, the zeta potential and the conformation of adsorbed molecules (the steric layer thicknesses) were measured as a function of the solution pH, the molecular weight and the surface charge. Photon correlation spectroscopy studies showed that the conformation of adsorbed molecules is strongly dependent on the solution pH, the molecular weight and the surface charge, suggesting that the dependence of stability on these parameters is due to the change of the conformation of the molecules adsorbed on the surface. In addition, the solution pH has a significant effect on the flocculation behavior of particles and can be modulated to bring about peptization of particles. This type of stabilization is referred to as electrosteric stabilization whereby steric stabilization is induced by changing the electrical properties of the system (the solution pH in this case). 41 refs., 43 figs., 10 tabs.

  14. Exponential Stabilization of Underactuated Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, K.Y.


    Underactuated vehicles are vehicles with fewer independent control actuators than degrees of freedom to be controlled. Such vehicles may be used in inspection of sub-sea cables, inspection and maintenance of offshore oil drilling platforms, and similar. This doctoral thesis discusses feedback stabilization of underactuated vehicles. The main objective has been to further develop methods from stabilization of nonholonomic systems to arrive at methods that are applicable to underactuated vehicles. A nonlinear model including both dynamics and kinematics is used to describe the vehicles, which may be surface vessels, spacecraft or autonomous underwater vehicles (AUVs). It is shown that for a certain class of underactuated vehicles the stabilization problem is not solvable by linear control theory. A new stability result for a class of homogeneous time-varying systems is derived and shown to be an important tool for developing continuous periodic time-varying feedback laws that stabilize underactuated vehicles without involving cancellation of dynamics. For position and orientation control of a surface vessel without side thruster a new continuous periodic feedback law is proposed that does not cancel any dynamics, and that exponentially stabilizes the origin of the underactuated surface vessel. A further issue considered is the stabilization of the attitude of an AUV. Finally, the thesis discusses stabilization of both position and attitude of an underactuated AUV. 55 refs., 28 figs.

  15. Stability of Polymer Solar Cells

    DEFF Research Database (Denmark)

    Jørgensen, Mikkel; Norrman, Kion; Gevorgyan, Suren


    Organic photovoltaics (OPVs) evolve in an exponential manner in the two key areas of efficiency and stability. The power conversion efficiency (PCE) has in the last decade been increased by almost a factor of ten approaching 10%. A main concern has been the stability that was previously measured ...

  16. Vibrations and Stability: Solved Problems

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003.......Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003....

  17. Apparatuses to support photovoltaic modules (United States)

    Ciasulli, John; Jones, Jason


    Methods and apparatuses to support photovoltaic ("PV") modules are described. A saddle bracket has a mounting surface to support one or more PV modules over a tube, a gusset coupled to the mounting surface, and a mounting feature coupled to the gusset to couple to the tube. A grounding washer has a first portion to couple to a support; and a second portion coupled to the first portion to provide a ground path to a PV module. A PV system has a saddle bracket; a PV module over the saddle bracket; and a grounding washer coupled to the saddle bracket and the PV module. Saddle brackets can be coupled to a torque tube at predetermined locations. PV modules can be coupled to the saddle brackets.

  18. Dispersion stability of thermal nanofluids

    Directory of Open Access Journals (Sweden)

    Fan Yu


    Full Text Available Thermal nanofluids, the engineered fluids with dispersed functional nanoparticles, have exhibited extraordinary thermophysical properties and added functionalities, and thus have enabled a broad range of important applications. The poor dispersion stability of thermal nanofluids, however, has been considered as a long-existing issue that limits their further development and practical application. This review overviews the recent efforts and progresses in improving the dispersion stability of thermal nanofluids such as mechanistic understanding of dispersion behavior of nanofluids, examples of both water-based and oil-based nanofluids, strategies to stabilize nanofluids, and characterization techniques for dispersion behavior of nanofluids. Finally, on-going research needs, and possible solutions to research challenges and future research directions in exploring stably dispersed thermal nanofluids are discussed. Keywords: Thermal nanofluids, Dispersion, Aggregation, Electrostatic stabilization, Steric stabilization

  19. Performance prediction of optical image stabilizer using SVM for shaker-free production line (United States)

    Kim, HyungKwan; Lee, JungHyun; Hyun, JinWook; Lim, Haekeun; Kim, GyuYeol; Moon, HyukSoo


    Recent smartphones adapt the camera module with optical image stabilizer(OIS) to enhance imaging quality in handshaking conditions. However, compared to the non-OIS camera module, the cost for implementing the OIS module is still high. One reason is that the production line for the OIS camera module requires a highly precise shaker table in final test process, which increases the unit cost of the production. In this paper, we propose a framework for the OIS quality prediction that is trained with the support vector machine and following module characterizing features : noise spectral density of gyroscope, optically measured linearity and cross-axis movement of hall and actuator. The classifier was tested on an actual production line and resulted in 88% accuracy of recall rate.

  20. Stability of modularity and structural keystone species in temporal cumulative plant- flower-visitor networks

    DEFF Research Database (Denmark)

    Dupont, Yoko; Olesen, Jens Mogens


    Modularity is a structural property of ecological networks, which has received much interest, but has been poorly explored. Modules are distinct subsets of species interacting strongly with each other, but sparsely with species outside the subset. Using a series of temporal cumulative networks, we...... investigated the stability of modular organization of pollination networks to temporal scaling. To test for modularity, we used the method ‘functional cartography by simulated annealing’ (Guimera` and Amaral, 2005a,b), a stochastic optimization technique. Modules are detected, and species classified into three...... types of topological roles in a network, based on patterns of within and between-module links: Hubs are highly connected species; peripherals interact with few species, mainly within their own module; and connectors have few interactions, too, but link across modules. We observed interactions between...

  1. Mechanical stability of roll-to-roll printed solar cells under cyclic bending and torsion

    DEFF Research Database (Denmark)

    Finn, Mickey; Martens, Christian James; Zaretski, Aliaksandr V.


    The ability of printed organic solar cells (OSCs) to survive repeated mechanical deformation is critical to large-scale implementation. This paper reports an investigation into the mechanical stability of OSCs through bending and torsion testing of whole printed modules. Two types of modules...... are used that differ slightly in thickness as well as on the basis of the electrode materials: silver nanowires or carbon-based inks. Each type of module is subjected to two different mechanical modes of deformation, bending and torsion, of several thousand cycles per module using a purpose-built robotic....... This crazing leads to eventual delamination due first to decohesion of the active layer at the edge of the modules and later to deadhesion between the PEDOT:PSS (electrode) and P3HT:PCBM (semiconductor) layers. The torsion mode imposes greater stresses than the bending mode and thus leads to failure at fewer...

  2. Declarative Debugging of Maude Modules


    Riesco Rodríguez, Adrián; Verdejo López, José Alberto; Caballero, Rafael; Martí Oliet, Narciso


    We introduce a declarative debugger for Maude modules: functional modules correspond to executable specifications in membership equational logic, while system modules correspond to rewrite theories. First we describe the construction of appropriate debugging trees for oriented equational and membership inferences and rewrite rules. These trees are obtained as the result of collapsing in proof trees all those nodes whose correction does not need any justification. We include severa...

  3. Reliability Research for Photovoltaic Modules (United States)

    Ross, Ronald J., Jr.


    Report describes research approach used to improve reliability of photovoltaic modules. Aimed at raising useful module lifetime to 20 to 30 years. Development of cost-effective solutions to module-lifetime problem requires compromises between degradation rates, failure rates, and lifetimes, on one hand, and costs of initial manufacture, maintenance, and lost energy, on other hand. Life-cycle costing integrates disparate economic terms, allowing cost effectiveness to be quantified, allowing comparison of different design alternatives.

  4. Hybrid grapheme plasmonic waveguide modulators (United States)

    Ansell, D.; Thackray, B. D.; Aznakayeva, D. E.; Thomas, P.; Auton, G. H.; Marshall, O. P.; Rodriguez, F. J.; Radko, I. P.; Han, Z.; Bozhevolnyi, S. I.; Grigorenko, A. N.


    The unique optical and electronic properties of graphene allow one to realize active optical devices. While several types of graphene-based photonic modulators have already been demonstrated, the potential of combining the versatility of graphene with sub-wavelength field confinement of plasmonic/metallic structures is not fully realized. Here we report fabrication and study of hybrid graphene-plasmonic modulators. We consider several types of modulators and identify the most promising one for light modulation at telecom and near-infrared. Our proof-of-concept results pave the way towards on-chip realization of efficient graphene-based active plasmonic waveguide devices for optical communications.

  5. Photovoltaic concentrator module improvements study

    Energy Technology Data Exchange (ETDEWEB)

    Levy, S.L.; Kerschen, K.A. (Black and Veatch, Kansas City, MO (United States)); Hutchison, G. (Solar Kinetics, Inc., Dallas, TX (United States)); Nowlan, M.J. (Spire Corp., Bedford, MA (United States))


    This report presents results of a project to design and fabricate an improved photovoltaic concentrator module. Using previous work as a baseline, this study conducted analyses and testing to select major module components and design features. The lens parquet and concentrator solar cell were selected from the highest performing, available components. A single 185X point-focus module was fabricated by the project team and tested at Sandia. Major module characteristics include a 6 by 4 compression-molded acrylic lens parquet (0.737 m{sup 2} area), twenty-four 0.2 ohms-cm, FZ, p-Si solar cells (1.56 cm{sup 2} area) soldered to ceramic substrates and copper heat spreaders, and an aluminized steel housing with corrugated bottom. This project marked the first attempt to use prismatic covers on solar cells in a high-concentration, point-focus application. Cells with 15 percent metallization were obtained, but problems with the fabrication and placement of prismatic covers on these cells lead to the decision not to use covers in the prototype module. Cell assembly fabrication, module fabrication, and module optical design activities are presented here. Test results are also presented for bare cells, cell assemblies, and module. At operating conditions of 981 watts/m{sup 2} DNI and an estimated cell temperature of 65{degrees}C, the module demonstrated an efficiency of 13.9 percent prior to stressed environmental exposure. 12 refs., 56 figs., 7 tabs.

  6. Perancangan Modul Penggajian Berbasis Odoo


    Koeswanto, Vincent K. Edison; Yulia, Yulia; Adipranata, Rudy


    Human Resource Module is one of the modules owned by Odoo. One of the feature of this module is payroll. However, the features is not in accordance with the needs of companies in Indonesia in general. This causes the payroll system in Odoo not suitable to be implemented directly in the company.To solve these problems, author develop the payroll system in Human Resource module in Odoo. The development of this system is preceded by designing and analyze the payroll system at PT X. It also condu...

  7. Estimation of multiply digital process control system extractive distillation stability

    Directory of Open Access Journals (Sweden)

    V. S. Kudryashov


    Full Text Available An approach to stability analysis of digital control systems associated non-stationary object on the example of the rectification process. Object modeling with cross-connections and the control scheme of the described system, discrete transfer functions in the shift operators. The equations of connection for each output of the closed-loop system. To solve this problem developed an algorithm for estimating the margin of stability of multivariable digital control systems based on the discrete root criterion, comprising the following main stages: obtaining of the characteristic polynomial of the closed-loop system for each output; computation of eigenvalues of the system matrix in the state space to determine roots of the characteristic equation and the stability of the system; determination of the stability and margin of stability by the deviation of maximum module of the root from the boundary of the high variability. To obtain the characteristic polynomial of a as discrete models of controllers and channels of IP object-use the transfer function of the first order with transport delay. The simulation was performed at different parameters of the control object, which is characterized by a stable and an unstable state of the system. VA-den analysis of the numerical values of the roots and character of their location on the complex plane, which to you-water that the system is stable or unstable. To confirm the obtained results were calculated and presented dynamic characteristics of the closed-loop system under different conditions, which confirm the initial assessment, the root criterion. To determine the factor stability of multivariable digital systems is proposed to use the deviation of the maximum root of the characteristic equation from the stability boundary. The obtained results apply to the class of symmetric multivariable control objects. The approach to assessing the sustainability of multivariable system regulation can be effectively

  8. Jet dynamics and stability

    Directory of Open Access Journals (Sweden)

    Perucho M.


    Full Text Available The dynamics and stability of extragalactic jets may be strongly influenced by small (and probable di_erences in pressure between the jet and the ambient and within the jet itself. The former give rise to expansion and recollimation of the jet. This occurs in the form of conical shocks, or Mach disks, if the pressure di_erence is large enough. Pressure asymmetries within the jet may trigger the development of helical patterns via coupling to kink current-driven instability, or to helical Kelvin-Helmholtz instability, depending on the physical conditions in the jet. I summarize here the evidence collected during the last years on the presence of recollimation shocks and waves in jets. In the jet of CTA 102 evidence has been found for (travelingshock-(standingshock interaction in the core-region (0.1 mas from the core, using information from the light-curve of the source combined with VLBI data. The conclusions derived have been confirmed by numerical simulations combined with emission calculations that have allowed to study the spectral evolution of the perturbed jet. Helical structures can also be identified in radio-jets. The ridge-line of emission of the jet of S5 0836+710 has been identified as a physical structure corresponding to a wave developing in the jet flow. I review here the evidence that has allowed to reach this conclusion, along with an associated caveat. Current data do not allow to distinguish between magnetic or hydrodynamical instabilities. I finally discuss the importance of these linear and non-linear waves for jet evolution.

  9. Quantifying Stability in Complex Networks: From Linear to Basin Stability (United States)

    Kurths, Jürgen

    The human brain, power grids, arrays of coupled lasers and the Amazon rainforest are all characterized by multistability. The likelihood that these systems will remain in the most desirable of their many stable states depends on their stability against significant perturbations, particularly in a state space populated by undesirable states. Here we claim that the traditional linearization-based approach to stability is in several cases too local to adequately assess how stable a state is. Instead, we quantify it in terms of basin stability, a new measure related to the volume of the basin of attraction. Basin stability is non-local, nonlinear and easily applicable, even to high-dimensional systems. It provides a long-sought-after explanation for the surprisingly regular topologies of neural networks and power grids, which have eluded theoretical description based solely on linear stability. Specifically, we employ a component-wise version of basin stability, a nonlinear inspection scheme, to investigate how a grid's degree of stability is influenced by certain patterns in the wiring topology. Various statistics from our ensemble simulations all support one main finding: The widespread and cheapest of all connection schemes, namely dead ends and dead trees, strongly diminish stability. For the Northern European power system we demonstrate that the inverse is also true: `Healing' dead ends by addition of transmission lines substantially enhances stability. This indicates a crucial smart-design principle for tomorrow's sustainable power grids: add just a few more lines to avoid dead ends. Further, we analyse the particular function of certain network motifs to promote the stability of the system. Here we uncover the impact of so-called detour motifs on the appearance of nodes with a poor stability score and discuss the implications for power grid design. Moreover, it will be shown that basin stability enables uncovering the mechanism for explosive synchronization and

  10. New pulse modulator with low switching frequency

    Directory of Open Access Journals (Sweden)

    Golub V. S.


    Full Text Available The author presents an integrating pulse modulator (analog signal converter with the pulse frequency and duration modulation similar to sigma-delta modulation (with low switching frequency, without quantization. The modulator is characterized by the absence of the quantization noise inherent in sigma-delta modulator, and a low switching frequency, unlike the pulse-frequency modulator. The modulator is recommended, in particular, to convert signals at the input of the class D power amplifier.

  11. Enhancement of Spanish Oesophageal Speech vowels using coherent subband modulator Kalman filtering. (United States)

    Ishaq, Rizwan; Zapirain, Begoña García


    This paper proposes an Oesophageal Speech (OES) enhancement method, based on Kalman filtering. The Kalman filter is applied to modulators of OES frequency subbands instead of the fullband signal. The OES frequency subbands are decomposed into modulators and carriers components using coherent demodulation. In comparison with fullband Kalman filtering and pole stabilization, the proposed technique shows better results. The system performance is evaluated objectively and subjectively using the Harmonic to Noise Ratio (HNR) and Mean Opinion Score (MOS) respectively. Results have shown that Kalman filter in subband modulators processing is robust and efficient, improving the HNR by 4 to 5 dB for all Spanish vowels.

  12. The electrochemical impact on electrostatic modulation of the metal-insulator transition in nickelates

    Energy Technology Data Exchange (ETDEWEB)

    Bubel, Simon; Glaudell, Anne M.; Mates, Thomas E.; Chabinyc, Michael L., E-mail: [Materials Research Laboratory (MRL), University of California Santa Barbara (UCSB), California 93106 (United States); Hauser, Adam J. [California Nanosystems Institute (CNSI), University of California Santa Barbara (UCSB), California 93106 (United States); Stemmer, Susanne [Materials Department, University of California Santa Barbara (UCSB), California 93106 (United States)


    For physical studies of correlated electron systems and for realizing novel device concepts, electrostatic modulation of metal-insulator transitions (MITs) is desired. The inherently high charge densities needed to modulate MITs make this difficult to achieve. The high capacitance of ionic liquids are attractive but, voltages are needed that can be in excess of the electrochemical stability of the system. Here, we show temperature/resistivity data that suggest electrostatic modulation of the MIT temperature of NdNiO{sub 3} in a wide regime. However, additional voltammetric and x-ray photoelectron spectroscopy measurements demonstrate the electrochemical impact of the electrostatic doping approach with ionic liquids.

  13. An analog modulation and demodulation method employing LVDT signal conditioner for fiber-optic interferometric sensors (United States)

    Zhou, Kejiang; Rao, Qi; Zhang, Minjie; Hu, Keke; Ruan, Yefeng


    An analog method to modulate and demodulate fiber-optic interferometric sensors employing a linear variable differential transformer signal conditioner to generate sine modulation wave and demodulate phase-modulated signal from the photodetector’s output is presented in this letter. No external lock-in amplifiers or digital components are used in this design. All the necessary components for signal processing are integrated in a single analog electronic microchip AD698, which reduces the system’s complexity significantly. After implementation on an interferometric fiber-optic gyroscope as an example, this method demonstrates a bias stability of 0.063 deg h-1 (i.e. 0.220 µrad).

  14. Stability of dispersions in polar organic media. I. Electrostatic stabilization

    NARCIS (Netherlands)

    Rooy, N. de; Bruyn, P.L. de; Overbeek, J.Th.G.

    Electrostatically stabilized sols of silver, silver iodide, α-goethite, and copper phthalocyanine in methanol, ethanol, isopropanol, and acetone have been prepared and characterized. Coagulation concentrations with electrolytes of various charge numbers have been determined in water, in organic

  15. Can the UN Stabilize Mali? Towards a UN Stabilization Doctrine?

    National Research Council Canada - National Science Library

    Arthur Boutellis


    ... of MINUSMA’s mandate and capabilities. It also raises a broader issue, of whether the consent-based UN peacekeeping tool is appropriate and can be effective in carrying out stabilization mandates in such a context and what doctrine...

  16. Protein native-state stabilization by placing aromatic side chains in N-glycosylated reverse turns. (United States)

    Culyba, Elizabeth K; Price, Joshua L; Hanson, Sarah R; Dhar, Apratim; Wong, Chi-Huey; Gruebele, Martin; Powers, Evan T; Kelly, Jeffery W


    N-glycosylation of eukaryotic proteins helps them fold and traverse the cellular secretory pathway and can increase their stability, although the molecular basis for stabilization is poorly understood. Glycosylation of proteins at naïve sites (ones that normally are not glycosylated) could be useful for therapeutic and research applications but currently results in unpredictable changes to protein stability. We show that placing a phenylalanine residue two or three positions before a glycosylated asparagine in distinct reverse turns facilitates stabilizing interactions between the aromatic side chain and the first N-acetylglucosamine of the glycan. Glycosylating this portable structural module, an enhanced aromatic sequon, in three different proteins stabilizes their native states by -0.7 to -2.0 kilocalories per mole and increases cellular glycosylation efficiency.

  17. Field investigation of keyblock stability

    Energy Technology Data Exchange (ETDEWEB)

    Yow, Jr., Jesse Lewis [Univ. of California, Berkeley, CA (United States)


    Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. This engineering problem is divided into two parts: block identification, and evaluation of block stability. One stable keyblock and thirteen fallen keyblocks were observed in field investigations at the Nevada Test Site. Nine blocks were measured in detail sufficient to allow back-analysis of their stability. Measurements included block geometry, and discontinuity roughness and compressive strength. Back-analysis correctly predicted stability or failure in all but two cases. These two exceptions involved situations that violated the stress assumptions of the stability calculations. Keyblock faces correlated well with known joint set orientations. The effect of tunnel orientation on keyblock frequency was apparent. Back-analysis of physical models successfully predicted block pullout force for two-dimensional models of unit thickness. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were examined. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls block displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender. Rock mass temperature decreases reduce the confining stress magnitudes and can lead to failure. The pattern of stresses affecting each block face explains conceptually the occurrence of pyramidal keyblocks that are truncated near their apex.

  18. Finite-time stability and finite-time stabilization (United States)

    Bhat, Sanjay Purushottam

    While non-Lipschitzian effects such as Coulomb friction abound in nature, most of the available techniques for feedback stabilization yield closed-loop systems with Lipschitzian dynamics. The convergence in such systems is at best exponential with infinite settling time. In this dissertation, we are interested in finite-settling-time behavior, that is, finite-time stability. The object of this dissertation is to provide a rigorous foundation for the theory of finite-time stability of continuous autonomous systems and motivate a closer examination of finite-time stability as a possible objective in control design. Accordingly, the notion of finite-time stability is precisely formulated and properties of the settling-time function are studied. Lyapunov and converse Lyapunov results involving scalar differential inequalities are obtained. It is shown that, under certain conditions, finite-time-stable systems possess better disturbance rejection and robustness properties. As an application of these ideas, we consider the finite-time stabilization of the translational and rotational double integrators. In the case of the rotational double integrator, the topology of the cylindrical state space renders continuous global stabilization impossible and hence the closed-loop system possesses saddle points. Because of the non-Lipschitzian character of the feedback law, these saddle points are, in fact, finite-time repellers--equilibria from which solutions can spontaneously and unpredictably depart. It is generally believed that models obtained from classical dynamics are completely deterministic. We present a counterexample to this widely held notion. The counterexample consists of a particle moving along a nonsmooth (once, but not twice, differentiable) constraint in a uniform gravitational field. The equation of motion obtained by applying classical Lagrangian dynamics contains non-Lipschitzian terms and, consequently, the dynamics of the system exhibit a finite-time saddle

  19. Silicon-photonic PTAT temperature sensor for micro-ring resonator thermal stabilization. (United States)

    Saeedi, Saman; Emami, Azita


    We present a scheme for thermal stabilization of micro-ring resonator modulators through direct measurement of ring temperature using a monolithic PTAT temperature sensor. The measured temperature is used in a feedback loop to adjust the thermal tuner of the ring. The closed-loop feedback system is demonstrated to operate in presence of thermal perturbations at 20Gb/s.

  20. Stability Analysis of a Three-Phase Solid-State Var Compensator ...

    African Journals Online (AJOL)

    The principal component of this device is a three-phase pulse-width-modulated voltage source inverter. A mathematical model of the inverter is derived in d-q referenceframe and then used to examine the stability of the compensator in response to variations in circuit parameters. Keywords: var compensation, inverter, ...

  1. Atomically Thin Ordered Alloys of Transition Metal Dichalcogenides: Stability and Band Structures

    DEFF Research Database (Denmark)

    Pandey, Mohnish; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer


    We explore the possibility of modulating the electronic band edges of the transition metal dichalcogenides (TMD) via alloying of different semiconductors within the same group (intra-group alloying). The stability of the ordered alloys is assessed from the calculated mixing enthalpy which is found...

  2. Sludge Stabilization Campaign blend plan

    Energy Technology Data Exchange (ETDEWEB)

    De Vries, M.L.


    This sludge stabilization blend plan documents the material to be processed and the order of processing for the FY95 Sludge Stabilization Campaign. The primary mission of this process is to reduce the inventory of unstable plutonium bearing sludge. The source of the sludge is residual and glovebox floor sweepings from the production of material at the Plutonium Finishing Plant (PFP). The reactive sludge is currently being stored in various gloveboxes at PFP. There are two types of the plutonium bearing material that will be thermally stabilized in the muffle furnace: Plutonium Reclamation Facility (PRF) sludge and Remote Mechanical C (RMC) Line material.

  3. Plutonium stabilization and packaging system

    Energy Technology Data Exchange (ETDEWEB)



    This document describes the functional design of the Plutonium Stabilization and Packaging System (Pu SPS). The objective of this system is to stabilize and package plutonium metals and oxides of greater than 50% wt, as well as other selected isotopes, in accordance with the requirements of the DOE standard for safe storage of these materials for 50 years. This system will support completion of stabilization and packaging campaigns of the inventory at a number of affected sites before the year 2002. The package will be standard for all sites and will provide a minimum of two uncontaminated, organics free confinement barriers for the packaged material.


    Directory of Open Access Journals (Sweden)

    Antonia Jaguljnjak Lazarević


    Full Text Available In this paper, basic structural stability phenomena are described. After some general comments about stability in the field of civil engineering, four elementary sources of nonlinearity are mentioned: of equilibrium equations, strain (geometry relations, material (stress-strain law, force and displacement boundary conditions. Four fundamental stability models are analysed, both ideal (perfect and with geometric imperfection. Besides geometrically exact theory, initial post-buckling behavior and linearization are briefly sketched. This paper is concluded with comments about the influence of plasticity.

  5. Modulational instability of nematic phase

    Indian Academy of Sciences (India)


    Feb 8, 2014 ... Abstract. We numerically observe the effect of homogeneous magnetic field on the modulation- ally stable case of polar phase in F = 2 spinor Bose–Einstein condensates (BECs). Also we investigate the modulational instability of uniaxial and biaxial (BN) states of polar phase. Our observations show that ...

  6. Modulational instability of nematic phase

    Indian Academy of Sciences (India)


    Feb 8, 2014 ... We numerically observe the effect of homogeneous magnetic field on the modulationally stable case of polar phase in = 2 spinor Bose–Einstein condensates (BECs). Also we investigate the modulational instability of uniaxial and biaxial (BN) states of polar phase. Our observations show that the magnetic ...

  7. CMS Inner Tracker Detector Modules

    CERN Document Server

    Sguazzoni, Giacomo


    The production of silicon detector modules that will instrument the CMS Inner Tracker has now a days reached 1300 units out of the approximately 3700 needed in total, with an overall yield close to 96%. A description of the module design, the assembly procedures and the qualification tests is given. The results of the quality assurance are presented and the experience gained is discussed.

  8. Survey of potential-induced degradation in thin-film modules (United States)

    Hacke, Peter; Terwilliger, Kent; Glick, Stephen H.; Perrin, Greg; Kurtz, Sarah R.


    CdTe and CIGS type modules were tested for potential-­-induced degradation with positive and negative 1,000 V bias applied to the active cell circuit in an 85°C, 85% relative humidity environmental chamber. Both CdTe module types tested exhibited degradation under negative bias. I-­-V curve data indicated the first module type was affected sequentially by shunting followed by a recovery and then by series resistance losses; the second was affected by recombination losses. The first type showed transparent conductive oxide delamination from the glass after about 750 h of stress testing in the environmental chamber and exhibited power degradation within five weeks in field tests with -­-1,000 V system voltage. Performance of CIGS modules differed depending on the technology generation. Under negative bias, the older module design showed an initial 12% (relative) improvement, possibly because of the influx of sodium ions that has been reported to benefit the electrical properties, followed by severe degradation with continued stress testing. The newer design CIGS module exhibited the best stability of the four thin-­-film module types tested with a total loss of 9.5 % (relative) power drop after 3,100 h of test with negative voltage bias, but not clearly by system voltage stress effects considering similar behavior by a sister module in-­-chamber in open-­-circuit condition. Relative rates of current leakage-­-to-­-ground between chamber tests and modules placed outdoors under system voltage stress are compared to extrapolate anticipated coulombs transferred for given extents of degradation of the module power. This analysis correctly placed which module type failed in the field first, but overestimated the time to failure. The performance of modules at 85°C with dark current Imp applied through the cell circuit are discussed with respect to stand-­-alone fielded modules biased to near their maximum power point with load resistors.

  9. Wideband laser locking to an atomic reference with modulation transfer spectroscopy. (United States)

    Negnevitsky, V; Turner, L D


    We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five.

  10. Modulation of the primary impulse of spatially-constrained video-aiming movements. (United States)

    Tinjust, David; Proteau, Luc


    It has been suggested that temporally-constrained goal directed movements are based on a single submovement control strategy that could be modulated online. On the contrary, spatially-constrained movements might encourage participants to produce very fast, open-loop, but somewhat inaccurate/variable primary movement impulses and, if necessary, to perform a discrete correction. We wanted to determine whether the primary impulse of a spatially-constrained manual aiming movement was modulated online. On movement extent, results revealed that a first modulation mechanism acted soon after movement initiation. This modulation was largely independent of target size and apparently stabilized the output of the movement planning processes. A second modulation mechanism further reduced the variability of the movement's primary impulse so that movements ended on target. Movement direction appeared to be under continuous control.

  11. Force Modulator System

    Energy Technology Data Exchange (ETDEWEB)

    Redmond Clark


    Many metal parts manufacturers use large metal presses to shape sheet metal into finished products like car body parts, jet wing and fuselage surfaces, etc. These metal presses take sheet metal and - with enormous force - reshape the metal into a fully formed part in a manner of seconds. Although highly efficient, the forces involved in forming metal parts also damage the press itself, limit the metals used in part production, slow press operations and, when not properly controlled, cause the manufacture of large volumes of defective metal parts. To date, the metal-forming industry has not been able to develop a metal-holding technology that allows full control of press forces during the part forming process. This is of particular importance in the automotive lightweighting efforts under way in the US automotive manufacturing marketplace. Metalforming Controls Technology Inc. (MC2) has developed a patented press control system called the Force Modulator that has the ability to control these press forces, allowing a breakthrough in stamping process control. The technology includes a series of hydraulic cylinders that provide controlled tonnage at all points in the forming process. At the same time, the unique cylinder design allows for the generation of very high levels of clamping forces (very high tonnages) in very small spaces; a requirement for forming medium and large panels out of HSS and AHSS. Successful production application of these systems testing at multiple stamping operations - including Ford and Chrysler - has validated the capabilities and economic benefits of the system. Although this technology has been adopted in a number of stamping operations, one of the primary barriers to faster adoption and application of this technology in HSS projects is system cost. The cost issue has surfaced because the systems currently in use are built for each individual die as a custom application, thus driving higher tooling costs. This project proposed to better

  12. Oxidative stability of marine phospholipids

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline Pascale

    Many studies have shown that marine phospholipids (MPL) provide more advantages than fish oil. They have better bioavailability, better resistance towards oxidation and higher content of eicosapentaenoic acids (EPA) and docosahexaenoic acids (DHA) than oily triglycerides (fish oil). The objective...... of this study is to investigate the oxidative and hydrolytic stability of MPL. In addition, this study also investigates the effect of chemical composition of MPL and Maillard reaction (interaction between lipids oxidation products with the residue of amino acids) on MPL emulsions’ stability. Firstly, MPL were...... prepared in the form of emulsions by high pressure homogenizer. Then, the oxidative and hydrolytic stability of phospholipids was investigated by measurement of simple chemical analyses such as Peroxide Value and Free Fatty Acids, and 31PNMR after 32 days storage at 2ºC. The oxidative stability of MPL...

  13. Thermal stability and kinetic constants for 129 variants of a family 1 glycoside hydrolase reveal that enzyme activity and stability can be separately designed.

    Directory of Open Access Journals (Sweden)

    Dylan Alexander Carlin

    Full Text Available Accurate modeling of enzyme activity and stability is an important goal of the protein engineering community. However, studies seeking to evaluate current progress are limited by small data sets of quantitative kinetic constants and thermal stability measurements. Here, we report quantitative measurements of soluble protein expression in E. coli, thermal stability, and Michaelis-Menten constants (kcat, KM, and kcat/KM for 129 designed mutants of a glycoside hydrolase. Statistical analyses reveal that functional Tm is independent of kcat, KM, and kcat/KM in this system, illustrating that an individual mutation can modulate these functional parameters independently. In addition, this data set is used to evaluate computational predictions of protein stability using the established Rosetta and FoldX algorithms. Predictions for both are found to correlate only weakly with experimental measurements, suggesting improvements are needed in the underlying algorithms.

  14. 47 CFR 78.115 - Modulation limits. (United States)


    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Modulation limits. 78.115 Section 78.115... SERVICE Technical Regulations § 78.115 Modulation limits. (a) If amplitude modulation is employed, negative modulation peaks shall not exceed 100 percent modulation. Pt. 78, Index Alphabetical Index—Part 78...

  15. C-11 Acid and the Stereochemistry of Abietic Acid

    Indian Academy of Sciences (India)

    IAS Admin

    carboxycyclohexylacetic acid. ... developed by Barton (1969 Chemistry Nobel Prize) to the solution of an important configurational problem, ... organic chemistry' and of the theoretical treatment of the chemical bond, essential to an understanding of ...

  16. Amino acid biogeo- and stereochemistry in coastal Chilean sediments

    DEFF Research Database (Denmark)

    Lomstein, Bente Aagaard; Jørgensen, Bo Barker; Schubert, Carsten J.


    aspartate and its non-protein degradation product β-alanine confirmed this observation. Furthermore, estimates of THAA mineralization showed that sedimentary amino acid reactivity decreased with both increasing water depth as well as progressive degradation status of the organic matter that was incorporated...... in the cores. The contribution of peptidoglycan amino acids to THAA was estimated from the concentrations of D-aspartate, D-glutamic acid, D-serine, and D-alanine. Peptidoglycan amino acids accounted for >18% of THAA in all investigated samples. In surface sediments peptidoglycan amino acids accounted......The spatial distribution of total hydrolysable amino acids (THAA) and amino acid enantiomers (D- and L-forms) was investigated in sediments underlying two contrasting Chilean upwelling regions,: at ~23°S off Antofagasta and at ~36°S off Concepcion. The contribution of amino acids to total organic...

  17. Assignment of the stereochemistry of the isomers of IQNP

    Energy Technology Data Exchange (ETDEWEB)

    McPherson, D.W.; Knapp, F.F. Jr. [Oak Ridge National Lab., TN (United States)


    The isomers of 1-azabicyclo[2.2.2]oct-3-yl {alpha}-hydroxy-{alpha}-(1-iodo-1-propen-3-yl)-{alpha}-phenylacetate (IQNP) are attractive for in vivo imaging of muscarinic receptors (mAChR). Although the stereocenter of the quinuclidinyl ring has been studied, the isomers of IQNP are oils and the configuration of the acetate center has not been elucidated. An improved synthesis of the acetate moiety (3) via a chiral intermediate has been developed and allows assignment of the configuration of the acetate. 1,3-dioxolan-4-one (1), (condensation of R- or S-mandelic acid and pivaldehyde) was alkylated with propargyl bromide, treated with base and esterified to afford R-(-)- or S-(+)-3. R- and S-3 were prepared in a 94:6 and 98:2 enantiomeric excess, respectively (HPLC analysis). R- and S-3 were utilized to synthesize the various isomers of IQNP. By comparing the optical rotation, HPLC and NMR of these isomers to those prepared by classical resolution allows the assignment of E-R, R-IQNP as the isomer demonstrating binding to M{sub 1} mAChR subtype and Z-R, R-IQNP as the isomer binding to M{sub 1} and M{sub 2}mAChR subtypes. This route also permits a simplified route for the preparation of the isomers of IQNP.

  18. Synthesis and Stereochemistry of Some (Silylamino)phosphinimines. (United States)


    is unlimited. Unclassified ECU ITY CLASSIFICATION OF THIS PAGE ("aen Data Entered) READ__ __ INSTRUCTIONS__ ___ __REPORT DOCUMENTATION PAGE BFRE...identified by comparison of its IH NMR to that of an authentic sample. Nearly a quantitative yield of phosphinimine 2a remained as a viscous yellow liquid of

  19. Pterandric acid--its isolation, synthesis and stereochemistry. (United States)

    Haleem, Muhammad A; Capellari, Simone C; Sympson, Beryl B; Marsaioli, Anita J


    Some plant families have a specialized type of pollination system, with floral lipid rewards for pollinators, which is common. In neotropical Malpighiaceae species like Pterandra pyroidea, this specialized type of pollination system is apparently shifting from floral oils/lipids to pollen reward. Mass spectrometric analysis (GC/MS-EI) indicated that P. pyroidea floral oil has a unique chemical composition, i.e., few fatty acid constituents possessing acetoxy groups at positions 5 and 7, which is distinct from the other floral oils of sympatric Malpighiaceae species. The structure of the major floral oil constituent, a novel fatty acid, anti-5,7-diacetoxydocosanoic acid, was confirmed based on synthesis, mass fragmentation, and 1H and 13C NMR analyses; the compound is herein named pterandric acid.

  20. Synthesis, stereochemistry and antimicrobial activity of copper(II ...

    African Journals Online (AJOL)

    On the basis of the analytical data, magnetic moments and spectral data, a square-planar geometry has been proposed for the nickel(II) and copper(II) complexes with these ligands. Some representative complexes of copper(II) and nickel(II) were found to have remarkable antifungal and antibacterial activity. KEY WORDS: ...

  1. Stereochemistry of substitution at trico-ordinate phosphorus

    DEFF Research Database (Denmark)

    Nielsen, John; Dahl, Otto


    A series of reactions of ring-substituted 1,3,2-dioxaphospholanes, 1,3,2-oxazaphospholanes, 1,2-oxaphospholes, and phosphetanes bearing the leaving groups Cl, OR, or NR2 on phosphorus, with the nucleophiles HCl, MeO-, MeOH, PhOH, Me2NH, Et2NH, and [CH 2]5NH have been studied. N.m.r. signals (1H a...

  2. Bottom-up elucidation of glycosidic bond stereochemistry

    DEFF Research Database (Denmark)

    Gray, Christopher J.; Schindler, Baptiste; Migas, Lukasz G.


    a particular challenge. Here, we show that "memory" of anomeric configuration is retained following gas-phase glycosidic bond fragmentation during tandem mass spectrometry (MS(2)). These findings allow for integration of MS(2) with ion mobility spectrometry (IM-MS(2)) and lead to a strategy to distinguish α...

  3. Cyclicity of stability in economy


    Kuzmin, Evgeny


    The article considers the science problem of identification of a life cycle of an economic agent in particular and of organizational-economic system in general. As an alternative solution of this problem the author proposes to use an universal index – stability index, which is directly linked with measure of uncertainty (entropy) and certainty (negentropy). Differentiated life cycle of stability allows us to approach the question of deliberate adaptation to ongoing changes, when control and r...

  4. Market liquidity and financial stability.


    Crockett, A.


    Stability in financial institutions and in financial markets are closely intertwined. Banks and other financial institutions need liquid markets through which to conduct risk management. And markets need the back-up liquidity lines provided by financial institutions. Market liquidity depends not only on objective, exogenous factors, but also on endogenous market dynamics. Central banks responsible for systemic stability need to consider how far their traditional responsibility for the health ...

  5. Financial Stability and Financial Inclusion


    Peter J. Morgan; Victor Pontines


    Developing economies are seeking to promote financial inclusion, i.e., greater access to financial services for low-income households and firms, as part of their overall strategies for economic and financial development. This raises the question of whether financial stability and financial inclusion are, broadly speaking, substitutes or complements. In other words, does the move toward greater financial inclusion tend to increase or decrease financial stability? A number of studies have sugge...

  6. Reliability criteria for voltage stability

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Carson W.; Silverstein, Brian L. [Bonneville Power Administration, Portland, OR (United States)


    In face of costs pressures, there is need to allocate scare resources more effectively in order to achieve voltage stability. This naturally leads to development of probabilistic criteria and notions of rick management. In this paper it is presented a discussion about criteria for long term voltage stability limited to the case in which the time frames are topically several minutes. (author) 14 refs., 1 fig.

  7. Subgrade stabilization alternatives to lime and cement. (United States)


    This project involved four distinct research activities, (1) the influence of temperature on lime-stabilized soils, (2) the influence of temperature on cement-stabilized soils (3) temperature modeling of stabilized subgrade and (4) use of calcium chl...

  8. Use of soil stabilizers on highway shoulders. (United States)


    This study evaluated soil additives as stabilizers for aggregate and topsoil shoulders. Its purpose was to determine (1) the effect soil stabilizers have on the strength and stability of soil shoulders, and (2) the costs and benefits of using stabili...

  9. Improving the Output Power Stability of a High Concentration Photovoltaic System with Supercapacitors: A Preliminary Evaluation

    Directory of Open Access Journals (Sweden)

    Yu-Pei Huang


    Full Text Available The output power of a high concentration photovoltaic (HCPV system is very sensitive to fluctuating tracking errors and weather patterns. To help compensate this shortcoming, supercapacitors have been successfully incorporated into photovoltaic systems to improve their output power stability. This study examined the output power stability improvement of an HCPV module with a supercapacitor integrated into its circuit. Furthermore, the equivalent model of the experimental circuit is presented and analyzed. Experimental results suggest that integrating a supercapacitor into an HCPV module could improve its output power stability and further extend its acceptance angle. This paper provides preliminary data of the improvement and its evaluation method, which could be utilized for further improvements to an HCPV system.

  10. Stability criteria for complex ecosystems. (United States)

    Allesina, Stefano; Tang, Si


    Forty years ago, May proved that sufficiently large or complex ecological networks have a probability of persisting that is close to zero, contrary to previous expectations. May analysed large networks in which species interact at random. However, in natural systems pairs of species have well-defined interactions (for example predator-prey, mutualistic or competitive). Here we extend May's results to these relationships and find remarkable differences between predator-prey interactions, which are stabilizing, and mutualistic and competitive interactions, which are destabilizing. We provide analytic stability criteria for all cases. We use the criteria to prove that, counterintuitively, the probability of stability for predator-prey networks decreases when a realistic food web structure is imposed or if there is a large preponderance of weak interactions. Similarly, stability is negatively affected by nestedness in bipartite mutualistic networks. These results are found by separating the contribution of network structure and interaction strengths to stability. Stable predator-prey networks can be arbitrarily large and complex, provided that predator-prey pairs are tightly coupled. The stability criteria are widely applicable, because they hold for any system of differential equations.

  11. Stability of p53 homologs.

    Directory of Open Access Journals (Sweden)

    Tobias Brandt

    Full Text Available Most proteins have not evolved for maximal thermal stability. Some are only marginally stable, as for example, the DNA-binding domains of p53 and its homologs, whose kinetic and thermodynamic stabilities are strongly correlated. Here, we applied high-throughput methods using a real-time PCR thermocycler to study the stability of several full-length orthologs and paralogs of the p53 family of transcription factors, which have diverse functions, ranging from tumour suppression to control of developmental processes. From isothermal denaturation fluorimetry and differential scanning fluorimetry, we found that full-length proteins showed the same correlation between kinetic and thermodynamic stability as their isolated DNA-binding domains. The stabilities of the full-length p53 orthologs were marginal and correlated with the temperature of their organism, paralleling the stability of the isolated DNA-binding domains. Additionally, the paralogs p63 and p73 were significantly more stable and long-lived than p53. The short half-life of p53 orthologs and the greater persistence of the paralogs may be biologically relevant.

  12. Stability of Pharmaceuticals in Space (United States)

    Nguyen, Y-Uyen


    Stability testing is a tool used to access shelf life and effects of storage conditions for pharmaceutical formulations. Early research from the International Space Station (ISS) revealed that some medications may have degraded while in space. This potential loss of medication efficacy would be very dangerous to Crew health. The aim of this research project, Stability of Pharmacotherapeutic Compounds, is to study how the stability of pharmaceutical compounds is affected by environmental conditions in space. Four identical pharmaceutical payload kits containing medications in different dosage forms (liquid for injection, tablet, capsule, ointment and suppository) were transported to the ISS aboard a Space Shuttle. One of the four kits was stored on that Shuttle and the other three were stored on the ISS for return to Earth at various time intervals aboard a pre-designated Shuttle flight. The Pharmacotherapeutics laboratory used stability test as defined by the United States Pharmacopeia (USP), to access the degree of degradation to the Payload kit medications that may have occurred during space flight. Once these medications returned, the results of stability test performed on them were compared to those from the matching ground controls stored on Earth. Analyses of the results obtained from physical and chemical stability assessments on these payload medications will provide researchers additional tools to promote safe and efficacious medications for space exploration.

  13. OCGen Module Mooring Project

    Energy Technology Data Exchange (ETDEWEB)

    McEntee, Jarlath [Ocean Renewable Power Company, LLC, Portland, ME (United States)


    Ocean Renewable Power Company's OCGen Module Mooring Project provided an extensive research, design, development, testing and data collection effort and analysis conducted with respect to a positively buoyant, submerged MHK device secured to the seabed using a tensioned mooring system. Different analytic tools were evaluated for their utility in the design of submerged systems and their moorings. Deployment and testing of a prototype OCGen® system provided significant data related to mooring line loads and system attitude and station keeping. Mooring line loads were measured in situ and reported against flow speeds. The Project made a significant step in the development of designs, methodologies and practices related to floating and mooring of marine hydrokinetic (MHK) devices. Importantly for Ocean Renewable Power Company, the Project provided a sound basis for advancing a technically and commercially viable OCGen® Power System. The OCGen® Power System is unique in the MHK industry and, in itself, offers distinct advantages of MHK devices that are secured to the seabed using fixed structural frames. Foremost among these advantages are capital and operating cost reductions and increased power extraction by allowing the device to be placed at the most energetic level of the water column.

  14. Fast polymer modulators (United States)

    Dalton, Larry


    Nanostructured organic electro-optic (EO) materials and devices have the potential to generate a revolution in telecommunications, information processing, display, and transportation technologies . Recently, drive voltages as low as 0.8 volts and operational bandwidths as large as 113 GHz have been demonstrated. The fabrication sophisticated 3-D passive/active optical circuits and the efficient integration of these with semiconductor VLSI electronics and silica transmission fibers have also been achieved. A number of impressive new prototype devices and phenomena have been demonstrated utilizing new materials. These include (1) frequency agile oscillators with bandwidths on the order of 100 GHz; (2) large angle 3-D optical beam steering; (3) time stretching over many orders of magnitude; (4) in-line and polarization-insensitive modulation; (5) optical gyroscopes; (6) acoustic spectrum analyzers; and (7) novel phased array radar systems. With amplification of electro-optic effects exploiting photonic bandgap and other resonating nano-structures, the possibility of detecting millivolt and even microvolt electrical signals exists. This would, in turn, create a revolution in sensor technology. The theoretical basis of design of improved organic EO materials is given and a number examples of new materials and devices are discussed.

  15. Living Systems Energy Module

    Energy Technology Data Exchange (ETDEWEB)



    The Living Systems Energy Module, renamed Voyage from the Sun, is a twenty-lesson curriculum designed to introduce students to the major ways in which energy is important in living systems. Voyage from the Sun tells the story of energy, describing its solar origins, how it is incorporated into living terrestrial systems through photosynthesis, how it flows from plants to herbivorous animals, and from herbivores to carnivores. A significant part of the unit is devoted to examining how humans use energy, and how human impact on natural habitats affects ecosystems. As students proceed through the unit, they read chapters of Voyage from the Sun, a comic book that describes the flow of energy in story form (Appendix A). During the course of the unit, an ``Energy Pyramid`` is erected in the classroom. This three-dimensional structure serves as a classroom exhibit, reminding students daily of the importance of energy and of the fragile nature of our living planet. Interactive activities teach students about adaptations that allow plants and animals to acquire, to use and to conserve energy. A complete list of curricular materials and copies of all activity sheets appear in Appendix B.

  16. Dynamic modelling of tearing mode stabilization by RF current drive

    Energy Technology Data Exchange (ETDEWEB)

    Giruzzi, G.; Zabiego, M.; Gianakon, T.A.; Garbet, X. [Association Euratom-CEA, CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Cardinali, A. [Association Euratom-ENEA sulla Fusione, Centro Ricerche Energia Frascati (Italy); Bernabei, S. [Princeton Univ., NJ (United States). Plasma Physics Lab.


    The theory of tearing mode stabilization in toroidal plasmas by RF-driven currents that are modulated in phase with the island rotation is investigated. A time scale analysis of the phenomena involved indicates that transient effects, such as finite time response of the driven currents, island rotation during the power pulses, and the inductive response of the plasma, are intrinsically important. A dynamic model of such effects is developed, based on a 3-D Fokker-Planck code coupled to both the electric field diffusion and the island evolution equations. Extensive applications to both Electron Cyclotron and Lower Hybrid current drive in ITER are presented. (author) 54 refs.

  17. Gait, Stability and Movement of Snake-Like Robots

    Directory of Open Access Journals (Sweden)

    Shengyong Chen


    Full Text Available This paper provides theoretical analysis of some key features of snake-like robot locomotion. Inspired by the moving mechanism of animals, the snake robot built with simple modules is numerically controlled. A most common method for its locomotion is to apply a central pattern generator to efficiently generate the control signals of gait and movement. This paper analyses stability, crawling gait, moving velocity, climbing capability, the capability to cross ditches and avoid obstacles, etc. Mathematical models and simulations show the theoretical validity and robot capabilities.

  18. On the Matlis duals of local cohomology modules and modules of ...

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 120; Issue 1. On the Matlis Duals of Local Cohomology Modules and Modules of Generalized Fractions. Kazem Khashyarmanesh. Volume ... Keywords. Local cohomology module; Matlis dual functor; module of generalized fractions; filter regular sequence.

  19. Long term stability of power systems

    Energy Technology Data Exchange (ETDEWEB)

    Kundur, P.; Gao, B. [Powertech Labs. Inc., Surrey, BC (Canada)


    Power system long term stability is still a developing subject. In this paper we provide our perspectives and experiences related to long term stability. The paper begins with the description of the nature of the long term stability problem, followed by the discussion of issues related to the modeling and solution techniques of tools for long term stability analysis. Cases studies are presented to illustrate the voltage stability aspect and plant dynamics aspect of long term stability. (author) 20 refs., 11 figs.

  20. Wavelength stabilized multi-kW diode laser systems (United States)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens


    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  1. PAIR FRAMES IN HILBERT C∗−MODULES 1. Introduction Frames ...

    Indian Academy of Sciences (India)


    results obtained for Bessel multipliers in Hilbert C∗−modules to pair frames and considering the stability of pair frames under invertible operators, we construct new pair frames and we show that pair frames are stable under small perturbations. 1. Introduction. Frames for Hilbert spaces were first introduced by Duffin and ...

  2. Outdoor W-Band Hybrid Photonic Wireless Link Based on an Optical SFP+ Module

    DEFF Research Database (Denmark)

    Rommel, Simon; Rodríguez Páez, Juan Sebastián; Chorchos, Łukasz


    This letter proposes aW-band hybrid photonic wireless link based on a commercial SFP+ module and experimentally demonstrates its performance. Using a free running laser as local oscillator and heterodyne photonic upconversion, good frequency stability is achieved. Outdoor wireless transmission ov...

  3. Citrem Modulates Internal Nanostructure of Glyceryl Monooleate Dispersions and Bypasses Complement Activation

    DEFF Research Database (Denmark)

    Wibroe, Peter P; Mat Azmi, Intan Diana Binti; Nilsson, Christa


    , modulates the internal nanostructure of LLC dispersions from a biphasic H2/L2 feature to a neat L2 phase, where the latter resembles 'thread-like' swollen micelles. Citrem stabilization totally overcomes hemolysis and complement activation, thus realizing the potential of the engineered LLC aqueous...

  4. The pharmacological effect of positive KCNQ (Kv7) modulators on dopamine release from striatal slices

    DEFF Research Database (Denmark)

    Jensen, Majbrit M; Lange, Sofie Cecilie; Thomsen, Morten Skøtt


    Retigabine is an anti-epileptic drug that inhibits neuronal firing by stabilizing the membrane potential through positive modulation of voltage-dependent KCNQ potassium channels in cortical neurons and in mesencephalic dopamine (DA) neurons. The purpose of this study was to compare the effect...

  5. Dynamic stability and phase resetting during biped gait (United States)

    Nomura, Taishin; Kawa, Kazuyoshi; Suzuki, Yasuyuki; Nakanishi, Masao; Yamasaki, Taiga


    Dynamic stability during periodic biped gait in humans and in a humanoid robot is considered. Here gait systems of human neuromusculoskeletal system and a humanoid are simply modeled while keeping their mechanical properties plausible. We prescribe periodic gait trajectories in terms of joint angles of the models as a function of time. The equations of motion of the models are then constrained by one of the prescribed gait trajectories to obtain types of periodically forced nonlinear dynamical systems. Simulated gait of the models may or may not fall down during gait, since the constraints are made only for joint angles of limbs but not for the motion of the body trunk. The equations of motion can exhibit a limit cycle solution (or an oscillatory solution that can be considered as a limit cycle practically) for each selected gait trajectory, if an initial condition is set appropriately. We analyze the stability of the limit cycle in terms of Poincaré maps and the basin of attraction of the limit cycle in order to examine how the stability depends on the prescribed trajectory. Moreover, the phase resetting of gait rhythm in response to external force perturbation is modeled. Since we always prescribe a gait trajectory in this study, reacting gait trajectories during the phase resetting are also prescribed. We show that an optimally prescribed reacting gait trajectory with an appropriate amount of the phase resetting can increase the gait stability. Neural mechanisms for generation and modulation of the gait trajectories are discussed.

  6. Promoting healthy weight with "stability skills first": a randomized trial. (United States)

    Kiernan, Michaela; Brown, Susan D; Schoffman, Danielle E; Lee, Katherine; King, Abby C; Taylor, C Barr; Schleicher, Nina C; Perri, Michael G


    Although behavioral weight-loss interventions produce short-term weight loss, long-term maintenance remains elusive. This randomized trial examined whether learning a novel set of "stability skills" before losing weight improved long-term weight management. Stability skills were designed to optimize individuals' current satisfaction with lifestyle and self-regulatory habits while requiring the minimum effort and attention necessary. Overweight/obese women (N = 267) were randomly assigned to one of two 6-month interventions and assessed at baseline and at 6, 12, and 18 months. Maintenance First women participated first in an 8-week stability skills maintenance module and then in a standard 20-week behavioral weight-loss program. Weight Loss First women participated first in a standard 20-week behavioral weight-loss program and then in a standard 8-week problem-solving skills maintenance module. There was no intervention staff contact during the 12-month follow-up period (6-18 months). As designed, Maintenance First participants lost the same percentage of initial weight during the 6-month intervention period as Weight Loss First participants (M = -8.6%, SD = 5.7, vs. M = -9.1%, SD = 6.9; t = -0.6, p = .52). However, Maintenance First participants regained significantly less weight during the 12-month follow-up period (6-18 months) than Weight Loss First participants (M = 3.2 lb, SD = 10.4, vs. M = 7.3 lb, SD = 9.9 [M = 1.4 kg, SD = 4.7, vs. M = 3.3 kg, SD = 4.5]; t = 3.3, p = .001, d = 0.4). Learning stability skills before losing weight was successful in helping women to maintain weight loss without intervention staff contact during follow-up. These results can inform the study design of future innovative interventions.

  7. [Research on methane concentration monitoring system based on electro-optical modulation interference]. (United States)

    Yan, Jie; Meng, Peng-Hua


    Gas monitoring for methane concentration has been applied in many areas, while the vast majority of methods were based on the chemical reaction. There is a low security and poor stability shortcomings. In contrast, it is of high stability and strong anti-interference ability to monitor methane concentration using optical interferometry for quantitative analysis. As the system static interference limits the spectrcum resolution, we designed the electro-optical modulation interference system to further improve the detection accuracy for methane concentration. In the interferometer system, a variable refractive index crystal LiNbO3 was used for electro-optical modulation, and the static optical path length scan range was increased to improve the spectrum resolution. Both sides of the crystal were loaded with opposite phase modulated signal, so that it does not change the improved spectrum resolution interferometer size. By derivation of refractive index modulation as a function of optical path difference, the simulation found that the resolution was increased by nearly an order of magnitude than interference system spectrum resolution of the same size. The experiments used the SGT-3-type acousto-optical modulator and the 1 650 nm infrared lasers to detect different concentrations of methane gas. The experimental results show that the method is better than the traditional pyroelectric method in terms of accuracy and stability, and more suitable for application in the mine complex environment.

  8. Evaluation of LED vehicular and pedestrian modules. (United States)


    This study was conducted to verify the compliance of vehicular and pedestrian LED traffic signal modules with the Institute : of Transportation Engineers specifications; and to assess drivers preferences of the LED modules. Four vehicular modules ...

  9. Photovoltaic module with adhesion promoter (United States)

    Xavier, Grace


    Photovoltaic modules with adhesion promoters and methods for fabricating photovoltaic modules with adhesion promoters are described. A photovoltaic module includes a solar cell including a first surface and a second surface, the second surface including a plurality of interspaced back-side contacts. A first glass layer is coupled to the first surface by a first encapsulating layer. A second glass layer is coupled to the second surface by a second encapsulating layer. At least a portion of the second encapsulating layer is bonded directly to the plurality of interspaced back-side contacts by an adhesion promoter.

  10. High-Efficiency Power Module (United States)

    Simons, Rainee N. (Inventor); Wintucky, Edwin G. (Inventor)


    One or more embodiments of the present invention pertain to an all solid-state microwave power module. The module includes a plurality of solid-state amplifiers configured to amplify a signal using a low power stage, a medium power stage, and a high power stage. The module also includes a power conditioner configured to activate a voltage sequencer (e.g., bias controller) when power is received from a power source. The voltage sequencer is configured to sequentially apply voltage to a gate of each amplifier and sequentially apply voltage to a drain of each amplifier.

  11. Complex Wavelet Based Modulation Analysis

    DEFF Research Database (Denmark)

    Luneau, Jean-Marc; Lebrun, Jérôme; Jensen, Søren Holdt


    Low-frequency modulation of sound carry important information for speech and music. The modulation spectrum i commonly obtained by spectral analysis of the sole temporal envelopes of the sub-bands out of a time-frequency analysis. Processing in this domain usually creates undesirable distortions...... polynomial trends. Moreover an analytic Hilbert-like transform is possible with complex wavelets implemented as an orthogonal filter bank. By working in an alternative transform domain coined as “Modulation Subbands”, this transform shows very promising denoising capabilities and suggests new approaches for joint...

  12. High Order Modulation Protograph Codes (United States)

    Nguyen, Thuy V. (Inventor); Nosratinia, Aria (Inventor); Divsalar, Dariush (Inventor)


    Digital communication coding methods for designing protograph-based bit-interleaved code modulation that is general and applies to any modulation. The general coding framework can support not only multiple rates but also adaptive modulation. The method is a two stage lifting approach. In the first stage, an original protograph is lifted to a slightly larger intermediate protograph. The intermediate protograph is then lifted via a circulant matrix to the expected codeword length to form a protograph-based low-density parity-check code.

  13. Light intensity modulation in phototherapy (United States)

    Lukyanovich, P. A.; Zon, B. A.; Kunin, A. A.; Pankova, S. N.


    A hypothesis that blocking ATP synthesis is one of the main causes of the stimulating effect is considered based on analysis of the primary photostimulation mechanisms. The light radiation intensity modulation is substantiated and the estimates of such modulation parameters are made. An explanation is offered to the stimulation efficiency decrease phenomenon at the increase of the radiation dose during the therapy. The results of clinical research of the medical treatment in preventive dentistry are presented depending on the spectrum and parameters of the light flux modulation.

  14. Modular crystals as modulated structures

    DEFF Research Database (Denmark)

    Elcoro, L.; Perez-Mato, J.M.; Friese, K.


    The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated...... and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements....

  15. Photodiode-Coupled Light Modulator (United States)

    Maserjian, Joseph; Eng, Sverre T.


    Absorption of one light beam controls transmission of another. High-performance monolithic light modulator comprised of p-doped/intrinsic/n-doped (PIN) GaAs photodiode grown directly over InAs/GaAs PIN multiple-quantum-well (MQW) diode. Photodiode-coupled multiple-quantum-well modulator includes advanced semi-conductor microstructures enhancing electro-optical properties. Using standard lithographic and etching techniques for defining picture elements, structures fabricated into two-dimensional arrays for use as spatial light modulators.

  16. Pulse code modulation telemetry: Properties of various binary modulation types (United States)

    Law, E. L.


    This report describes the results of a study that was conducted to determine the properties of several binary pulse code modulation types. The topics addressed include: (1) Radio frequency spectral occupancy, (2) Bit error rate versus intermediate frequency signal-to-noise ratio in a bandwidth equal to the bit rate, (3) Peak carrier deviation, (4) Effect of filtering on data quality, and (5) Frequency and phase modulation.

  17. Modulation of lymphopoiesis

    Energy Technology Data Exchange (ETDEWEB)

    Rosse, C.


    Ongoing experiments contribute to the four specific aims in our current 3-year project period studying lymphopoiesis using CE mammary adenocarcinoma (CE maca) mice. Specific Aim 1: Function of Bone Marrow Stroma in CE Maca Bearing Mice. We have concluded that bone marrow stromal cells from tumor bearing animals are as effective as bone marrow stromal cells from normal animals at supporting B lymphopoiesis in culture. If stromal cell disfunction occurs in tumor bearing animals, the effect is not long lasting. Specific Aim 2: Factors Elaborated by CE Maca. Conditioned medium from CE maca cultures induces bone resorbing activity in bone organ cultures. We have identified a 32 kDa protein that meets the criteria for an osteoclast specific growth factor in this medium. However, we have also found that even though an osteoclast specific growth factor exists, a growth factor whose primary targets are granulocyte precursors will also stimulate osteoclast activity. Specific Aim 3: In Vitro Systems for Investigating Modulation of NK Lymphopoiesis by CE Maca. CE maca is shown to inhibit NK all production as well as B all production. In the course of the these experiments, we have established conditions for enriching NK precursors and have established a prototype long term bone marrow culture system which shows NK cell production. Specific Aim 4: Relationship Between Myclogenic and Intrathymic T Cell Precursors. There is evidence for a stream of T all maturation in both host (or intrathymic) cells and non-host (both hematogenous and intrathymic) cells. If thymic atrophy is induced by cortisone (a depopulation equivalent to that caused by 1000 rad) our data conclusively show thymic recovery is effected almost exclusively by intrathymic cells. This assigns a much greater importance to intrathymic T all progenitors in the maintenance of T cell production in the thymus than has been hitherto recognized. (MHB)

  18. Modulation of lymphopoiesis

    Energy Technology Data Exchange (ETDEWEB)

    Rosse, C.


    During the current project period we have demonstrated correspondence between animal models and in vitro models of modulated lymphopoiesis. Our finding that G-CSF, a growth factor for neutrophil granulocytes, suppresses lymphopoiesis in long term bone marrow cultures (LTBMC) has important implications both for understanding the regulatory mechanisms of hemopoiesis and for clinical use of recombinant growth factors that are beginning to be widely used for the treatment of a variety of diseases. During the present project period we adopted LTBMC systems developed by others for the purposes of our specific aims. Also we developed a novel long term culture system for NK cells. The discovery of a new growth factor, O-CSF, specific for osteoclasts and the establishment of a clonal assay system that provides evidence for a new class of hemopoietic progenitor cells, the osteoclast progenitor, are important contributions. Given the important role T cells play in the immune response and in the regulation of other lymphohemopoietic cell lineages through the lymphokines they secrete, the need for an in vitro system that lends itself to the analysis of T cell maturation and to the testing of factors that may adversely affect T lymphopoiesis cannot be overemphasized. We believe that we can exploit an advantageous set of circumstances that present an excellent opportunity for initiating a focused experimental program for developing such a system. By a systematic and selective analysis of molecular interactions between heterogenous thymic stromal cells and T cell progenitors at different stages of maturation, it will be possible for our program to define the complement of critical cellular interactions on which successive stages of T lymphopoiesis depend. The experiments we propose will lay a rational foundation for the development of a long term culture system for T lymphopoiesis. 24 refs., 7 figs.

  19. Stability Analysis and Stabilization of Miduk Heap Leaching Structure, Iran

    Directory of Open Access Journals (Sweden)

    Mehdi Amini


    Full Text Available To construct copper heap leaching structures, a stepped heap of ore is placed over an isolated sloping surface and then washed with sulphuric acid. The isolated bed of such a heap consists of some natural and geosynthetic layers. Shear strength parameters between these layers are low, so they form the possible sliding surfaces of the heaps. Economic and environmental considerations call for studying such slides. In this study, firstly, results of the laboratory tests carried on the materials of the heap leaching structures bed are presented. Then, the instability mechanisms of such structures are investigated and proper approaches are summarized for their stabilization. Finally, stability of the Miduk copper heap is evaluated as a case history, and appropriate approaches and their effects are discussed for its stabilization.

  20. Can the UN Stabilize Mali? Towards a UN Stabilization Doctrine?

    Directory of Open Access Journals (Sweden)

    Arthur Boutellis


    Full Text Available Almost two years after the deployment of the United Nations Multidimensional Integrated Stabilization Mission in Mali (MINUSMA in July 2013, the increasing number of asymmetric terrorist attacks targeting UN peacekeepers – in the context of a drawn-out peace process – has raised a number of questions in Mali, the sub-region, and in New York, over the relevance and adequacies of MINUSMA’s mandate and capabilities. It also raises a broader issue, of whether the consent-based UN peacekeeping tool is appropriate and can be effective in carrying out stabilization mandates in such a context and what doctrine such operations should be based on. The UN is indeed under increasing pressure from host countries and some African troop-contributing countries to go on the offensive. Member States have also increasingly recognized terrorism and organized crime as a strategic threat, and while opposed to the UN directly engaging in counterterrorism (CT operations, some may wish to see the UN playing a greater stabilization role following the January 2013 French military intervention in Mali. However, little guidance and means have been given so far to UN missions for dealing with such threats and implementing effective stabilization mandates. The High-Level Panel on Peace Operations, which recently released its report, noted that the usage of the term “stabilization” by the UN requires clarification. This article analyses the complex and evolving nature of threats in northern Mali and implications for MINUSMA and describes the military and political tools – including mediation – so far available within and outside the UN. The article concludes that the UN is bound to move towards stabilization when and if deployed in contexts such as Mali’s if it wants to remain relevant. However, such a move should be based on an overarching UN stabilization doctrine and context-specific UN-wide stabilization strategies which are first and foremost political