Three-way Switch Research Articles

An Anion‐Modulated Three‐Way Supramolecular Switch that Selectively Binds Dihydrogen Phosphate, H2PO4−

An anionic three-way switch: A bipyridyl bis(urea)-based anion receptor that is highly selective for dihydrogen phosphate demonstrates spectroscopically distinct anion-bound conformations toward halides and select oxoanions. 1H NMR studies show the differing anion-induced conformations are reversible allowing this system to function as a three-way molecular switch.

A whole-air relaxed eddy accumulation measurement system for sampling vertical vapour exchange of elemental mercury

An apparatus relying on relaxed eddy accumulation (REA) methodology has been designed and developed for continuous-field measurements of vertical Hg0 fluxes over cropland ecosystems. This micro-meteorological technique requires sampling of turbulent eddies into up- and downdraught channels at a constant flow rate and accurate timing, based on a threshold involving the sign of vertical wind component (w). The fully automated system is of a whole-air type drawing air at a high velocity to the REA sampling apparatus and allowing for the rejection of samples associated with w-fluctuations around zero. Conditional sampling was executed at 10-Hz resolution on a sub-stream by two fast-response three-way solenoid switching valves connected in parallel to a zero Hg0 air supply through their normally open ports. To suppress flow transients resulting from switching, pressure differentials across the two upstream ports of the conditional valves were minimised using a control unit. The Hg0 concentrations of the up- and downdraught channel were sequentially (each by two consecutive 5-minute gas samples) determined after enhancement collection onto gold traps by an automated cold vapour atomic fluorescence spectrophotometer (CVAFS) instrument. A protocol of regular reference sampling periods was implemented during field campaigns to continuously adjust for bias that may exist between the two conditional sampling channels. Using a 5-minute running average was conditional threshold, nearly-constant relaxation coefficients (βs) of ~0.56 were determined during two bi-weekly field deployments when turbulence statistics were assured for good quality, in accordance with previously reported estimates. The fully developed REA-CVAFS system underwent Hg0 flux field trial runs at a winter wheat cropland located in the North China Plain. Over a 15-d period during early May 2012, dynamic, often bi-directional, fluxes were observed during the course of a day with a tendency of emission (Hg0 median flux of 77.1 ng m−2 h−1) during daytime and fluctuation around zero (Hg0 median flux of 9.8 ng m−2 h−1) during nighttime.

Three-way switching in a cyanide-bridged [CoFe] chain

Bistable compounds that exist in two interchangeable phases under identical conditions can act as switches under external stimuli. Among such switchable materials, coordination complexes have energy levels (or phases) that are determined by the electronic states of their constituent metal ions and ligands. They can exhibit multiple bistabilities and hold promise in the search for multifaceted materials that display different properties in different phases, accessible through the application of contrasting external stimuli. Molecular systems that exhibit both thermo- and photoinduced magnetic bistabilities are excellent candidates for such systems. Here we describe a cyanide-bridged [CoFe] one-dimensional chiral coordination polymer that displays both magnetic and electric bistabilities in the same temperature range. Both the electric and magnetic switching probably arise from the same electron-transfer coupled spin-transition phenomenon, which enables the reversible conversion between an insulating diamagnetic phase and either a semiconducting paramagnetic (thermoinduced) or a type of ferromagnetic single-chain magnet (photoinduced) state.

Four-Port Optical Switch Having Three Connection States With Si Waveguides

We propose a novel four-port optical switch, which has three possible connection states among the four ports. The device consists of two cross-bar switches, which join with unique connections. We fabricate a four-port optical switch composed of Mach-Zehnder interferometer switches with silicon waveguides; the fabricated switch has a small footprint of 800 × 400 μm2. The three-way switching operation with extinction ratios of up to 30 dB and switching time of 40 μs is demonstrated at telecom wavelengths.

Tryptophan as a three-way switch in regulating the function of the secretory signalling glycoprotein (SPS-40) from mammary glands: structure of SPS-40 complexed with 2-methylpentane-2,4-diol at 1.6 Å resolution

The 40 kDa secretory signalling glycoprotein (SPS-40) is the first example with Trp78 in three functional orientations: (i) a resting state with a pinched conformation, (ii) a stacked conformation when bound to hexasaccharide and (iii) an obstructive conformation when inhibited by 2-methylpentane-2,4-diol (MPD). Trp78 is present in the core of the sugar-binding groove. The hexasaccharide N-acetylglucosamine (GlcNAc(6)) has been shown to bind to SPS-40. As a result of this, the conformation of Trp78 alters from the native pinched conformation (chi(1) = -65.5 degrees , chi(2,1) = -78.8 degrees , chi(2,2) = 97.5 degrees ) to the stacked conformation (chi(1) = -170.0 degrees , chi(2,1) = -114.3 degrees , chi(2,2) = 61.6 degrees ). Further binding experiments showed that saccharide binding does not occur in the presence of 20% MPD. The crystal structure determination of the complex of SPS-40 with MPD revealed the presence of two MPD molecules in the sugar-binding groove. The very tightly bound MPD molecules at subsites -2 and -1 induced an unexpected and a rarely observed conformation of Trp78 (chi(1) = 55.9 degrees , chi(2,1) = 90.2 degrees , chi(2,2) = -88.9 degrees ) which is termed an obstructive conformation. The binding of MPD molecules also twisted the side chains of Glu269 and Ile272 considerably. These residues are also part of the sugar-binding groove. The observed obstructive conformation of the side chain of Trp78 in the present structure is the exact opposite of the stacked conformation. This rarely observed conformation is stabilized by a number of hydrogen bonds between Trp78 and Asn79 through water molecules W49, W229, W269, W547 and W557.

Fully compliant double tensural tristable micromechanisms (DTTM)

Numerous possible micromechanism applications (e.g. three-way switches, mechanical memory and multiplex optical switches) could benefit from a device with three stable equilibrium positions. In this paper, we present a new class of tristable mechanisms called double tensural tristable mechanisms (DTTMs) which are fully compliant (i.e. they are monolithic and get their motion from the deflection of elastic components) and can be fabricated at the micro scale. A pseudo-rigid-body model (PRBM) for the DTTM has been developed. DTTMs were fabricated in polysilicon using the SUMMiT V process and tested for tristability and force–deflection characteristics. The results successfully demonstrate tristable behavior and show that the PRBM can be used to identify tristable configurations and predict their performance.

A new three-way supramolecular switch based on redox-controlled interconversion of hetero- and homo-guest-pair inclusion inside a host molecule

A novel three-way supramolecular switch based on the interconversion of hetero-guest-pair (D-A) and homo-guest-pair (D(2) or A(2)) inclusion inside cucurbit[8]uril is reported, which can be selectively controlled by chemical or electrochemical stimuli.

Close‐up of a replisome

The assembly of proteins, the replisome, that replicates DNA is comprised of molecular motors and switches that coordinate reactions through multiple interactions. Although differing in complexity, the basic machinery of all replication systems is remarkably conserved throughout evolution. The economy of proteins found in the replication system of bacteriophage T7 has made possible the analysis of a replisome at the molecular level. Four proteins of known crystal structure are sufficient for the basis reactions: T7 DNA polymerase and its processivity factor (E. coli thioredoxin), T7 helicase-primase, and T7 ssDNA binding protein. A reconstituted replisome effects DNA synthesis in which leading and lagging strand synthesis are coordinated and processive. Nascent Okazaki fragments are found within a loop of lagging strand DNA. Occupancy of the nucleotide binding sites of the hexameric helicase, located between adjacent subunits, modulate DNA binding via conformational changes. The transfer of ssDNA from subunit to subunit is coupled to the sequential hydrolysis of dTTP. The recycling of the lagging strand DNA polymerase requires multiple steps and interactions. Interactions between the helicase and primase domains result in the pausing of leading strand synthesis observed during primer synthesis in single molecule experiments. Thioredoxin binds to a unique 76 amino acid fragment located in the thumb sub-domain of T7 DNA polymerase initiating conformational changes that lead to interactions with the primer-template, the helicase-primase, and the ssDNA binding protein. The acidic C-termini of the latter two proteins are essential for these interactions. Thus a three-way switch mediates the interactions of the multiple components during DNA synthesis. Supported by USPHS Grant GM 54397.

Universal three-way few-electron switch using silicon single-electron transistors

A three-way few-electron switch is implemented using bidirectional electron pumps in silicon-on-insulator material. The switch consists of three branches defined by single-electron transistors, connected to a central node. Any combination of two single-electron transistors forms a bidirectional electron pump. At 4.2K, each cycle of an rf signal applied to the central node pumps electron packets approximately ten electrons in size through the circuit. It is possible to switch the electron packets in any direction through the branches. The switch may be used for the precise transfer of electrons, and as the basic element in few-electron logic applications.

Proton controlled intramolecular communication in dinuclear ruthenium(II) polypyridine complexes.

The synthesis and characterization of two dinuclear ruthenium polypyridyl complexes based on the bridging ligands 5,5'-bis(pyridin-2' '-yl)-3,3'-bis(1H-1,2,4-triazole) and 5,5'-bis(pyrazin-2' '-yl)-3,3'-bis(1H-1,2,4-triazole) and of their mononuclear precursors are reported. The dinuclear compounds have been prepared by a Ni(0) catalyzed coupling of a mononuclear ruthenium(II) polypyridyl complex containing a brominated triazole moiety. Electrochemical and photophysical studies indicate that, in these dinuclear complexes, the protonation state of the bridge may be used to tune the intercomponent interaction between the two metal centers and that these species act as proton driven three-way molecular switches that can be read by electrochemical or luminescence techniques.

Pi-Switches: Synthesis of Three-Way Molecular Switches Based on the Dimethyldihydropyrene−Metacyclophanediene Valence Isomerization

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPi-Switches: Synthesis of Three-Way Molecular Switches Based on the Dimethyldihydropyrene−Metacyclophanediene Valence IsomerizationReginald H. Mitchell, Timothy R. Ward, Yunxia Wang, and Peter W. DibbleView Author Information Department of Chemistry, University of Victoria PO Box 3065, Victoria, BC, Canada, V8W 3V6 Department of Chemistry, University of Lethbridge Alberta, Canada, T1K 3M4 Cite this: J. Am. Chem. Soc. 1999, 121, 11, 2601–2602Publication Date (Web):March 4, 1999Publication History Received6 November 1998Published online4 March 1999Published inissue 1 March 1999https://doi.org/10.1021/ja983848kCopyright © 1999 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views560Altmetric-Citations50LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (91 KB) Get e-AlertsSUBJECTS:Aromatic compounds,Electromagnetic radiation,Hydrocarbons,Irradiation,Molecular structure Get e-Alerts

Separation of polymer and on-line determination of several antioxidants and UV stabilizers by coupling size-exclusion and normal-phase high-performance liquid chromatography columns

A procedure consisting of connecting in series two different HPLC columns, one for size-exclusion chromatography (SEC) and the second one a normal-phase (silica) column has been developed. An automatic three-way switching valve was placed between the two columns. Through the valve, the polymer was drained whereas the rest of the compounds, a group of antioxidants and UV stabilizers, were separated and analyzed in the second column. The behaviour of the SEC column in different organic phases is studied. Detection limits about 0.1 μg ml −1 were obtained for BHT, Tinuvin 326 and Tinuvin 327; 0.2 μg ml −1 for Irganox 1076, and 1.1 μg ml −1 for Cyasorb UV 9 and Cyasorb UV 1084. R.S.D. values of the whole process are lower than 4%.

A simple method for studying lung ventilation

A simple method of precisely administering a compact gas bolus during selectable portions of the inspiratory cycle was developed to examine certain fundamental attributes of lung physiology and ventilation. The method allows for a small, well-defined bolus to be delivered during different phases of inspiration in a precise fashion. A pneumatically driven three-way switching valve is synchronized to the breathing pattern and controls the interjection of radioxenon boli in the inspiratory stream, spiking a small portion of the inhaled breath. The 133Xe dispersion and redispersion in the lungs is mapped and the clearance followed. Regional differences are analysed to determine how ventilation might influence the development of lung diseases due to inhaled toxins. Scintillation imaging at 20 frames s-1 allows near real-time characterization of the ventilation distribution. Novelty comes from the application of fast data gathering, the flow through valve design for delivery of tightly compacted boli and from tracing different fractions of the breath. The procedure involves low radiation exposure. An apparatus and method for acquiring data on lung filling and emptying not previously available is described. Potential applications are identified which may allow the re-examination of orthodox lung physiology.

Quality control of ER synthesized proteins: an exposed thiol group as a three-way switch mediating assembly, retention and degradation.

Plasma cells secrete IgM only in the polymeric form: the C-terminal cysteine of the mu heavy chain (Cys575) is responsible for both intracellular retention and assembly of IgM subunits. Polymerization is not quantitative, and part of IgM is degraded intracellularly. Neither chloroquine nor brefeldin A (BFA) inhibits degradation, suggesting that this process occurs in a pre-Golgi compartment. Degradation of IgM assembly intermediates requires Cys575: the monomeric IgMala575 mutant is stable also when endoplasmic reticulum (ER) to Golgi transport is blocked by BFA. Addition of the 20 C-terminal residues of mu to the lysosomal protease cathepsin D is sufficient to induce pre-Golgi retention and degradation of the chimeric protein: the small amounts of molecules which exit from the ER are mostly covalent dimers. By contrast, when retained by the KDEL sequence, cathepsin D is stable in the ER, indicating that retention is not sufficient to cause degradation. Replacing the C-terminal cysteine with serine restores transport through the Golgi. As all chimeric cathepsin D constructs display comparable protease activity in vitro, their different fates are not determined by gross alterations in folding. Thus, also out of its normal context, the mu chain Cys575 plays a crucial role in quality control, mediating assembly, retention and degradation.

System for selection and phase control of humbucking coils in guitar pickups

A system for the selection and phase control of humbucking coils in electromagnetic guitar pickups to permit the musician to easily select different sounds using digital memory means for storing different combinations of gate control bits to select the pickup coils to be used, the phase of the coils selected and the output level of the selected coils combined. A three-way switch is used to count up, count down or hold a memory address for selection of a combination. The address is displayed for verification. Memories may be prestored ROMs, or alterable RAMs in which write enable control is controlled by a three-way switch. Three address counters may be provided to permit the musician to quickly select from three predetermined combinations through operation of a three-way switch.

Single-pump solvent programmer for high-performance liquid chromatography using synchronized valve switching

The performance of several commercial high-performance liquid chromatography solvent programmers has been tested for isocratic and gradient elution. Significant differences have been observed between the imposed and the actually delivered composition of the solvent mixture. The deviations can be traced to the principal limitations of the presently available single- or dual-pump programmers. Such shortcomings have been overcome in a single programmer that can be incorporated in any reciprocating piston pump. The design uses a three-way valve switching periodically between two solvents. Because the valve switching is synchronized with each refill stroke of the pump, highly stable, reproducible and accurate binary compositions can be delivered in both isocratic and gradient elution. The principle is easily extended to ternary systems.

A Dual-Channel Microwave Radiometer for Measurement of Precipitable Water Vapor and Liquid

The design and performance of a two-channel ground-based microwave radiometer (20.6 and 31.6 GHz) for measurement of total integrated water vapor and cloud liquid in a vertical column are discussed. Unique features of this instrument are a single antenna producing equal beamwidth for the two frequencies, and incorporation of two stable reference loads in a three-way Dicke switching sequence. The latter allows an automatic gain control (AGC) to be applied in a minicomputer. Linear statistical inversion is used to retrieve the precipitable water vapor and liquid quantities which are provided in real time. The instrument has been in reliable operation, continuously and unattended, at the National Weather Service Forecast Office, Denver, CO, for a six-month period. The radiometrically derived precipitable water vapor compares favorably with that obtained from radiosondes.

Transients and crises — An essay on common sense

SOME YEARS AGO, the sister of Karl Compton, whose husband was the head of an educational institution abroad, was having her house wired by a native electrician who constantly came to her with questions such as “Where do you want the wires?” “How many plugs?” “Do you want three-way switches?” She finally said, “Oh, you know what I want, just use your common sense.” He replied politely: “Madam, common sense is a gift of God. I have only a technical education.”

A High-Speed K-Band Switch

A high-speed rotary three-way switch for 1.25 centimeter waves is described. An application for rapid scanning and performance characteristics are given.