Complete Interconversion Research Articles

Heralded and Complete Interconversion Between W State and Knill–Laflamme–Milburn State via State‐Selective Reflection with Robust Fidelity

AbstractThe interconversion of different types of entangled states not only can realize the information transmission but also play a significant role in quantum information technologies, including increasing scalability and computational power, and reducing error rates. Here, two protocols for achieving a complete interconversion between W state and Knill–Laflamme–Milburn state assisted by the quantum dot (QD)‐cavity systems and common quantum control gates are proposed. In particular, the protocols employ a heralded approach strategically designed to predict potential failures and facilitate seamless interaction between the QD‐cavity system and photons with the help of a single photon detectors, enhancing experimental accessibility. Through extensive analyzes and evaluations of two protocols, the proposed two protocols achieve remarkable utilization rates of photons (i.e., unit in principle) and achieve near‐unit fidelities and high efficiencies in principle.

Polyaniline nanowire arrays generated through oriented mesoporous silica films: effect of pore size and spectroelectrochemical response.

Indium-tin oxide electrodes modified with vertically aligned silica nanochannel membranes have been produced by electrochemically assisted self-assembly of cationic surfactants (cetyl- or octadecyl-trimethylammonium bromide) and concomitant polycondensation of the silica precursors (tetraethoxysilane). They exhibited pore diameters in the 2-3 nm range depending on the surfactant used. After surfactant removal, the bottom of mesopores was derivatized with aminophenyl groups via electrografting (i.e., electrochemical reduction of in situ generated aminophenyl monodiazonium salt). These species covalently bonded to the ITO substrate were then exploited to grow polyaniline nanofilaments by electropolymerization of aniline through the nanochannels. Under potentiostatic conditions, the length of polyaniline wires is controllable by tuning the electropolymerization time. From cyclic voltammetry characterization performed either before or after dissolution of the silica template, it appeared that both the polyaniline/silica composite and the free polyaniline nanowire arrays were electroactive, yet with much larger peak currents in the latter case as a result of larger effective surface area offered to the electrolyte solution. At identical electropolymerization time, the amount of deposited polyaniline was larger when using the silica membrane with larger pore diameter. All polyaniline deposits exhibited electrochromic properties. However, the spectroelectrochemical data indicated more complete interconversion between the coloured oxidized form and colourless reduced polyaniline for the arrays of nanofilaments in comparison to bulky films. In addition, the template-free nanowire arrays (i.e., after silica dissolution) were characterized by faster electrochromic behaviour than the polyaniline/silica hybrid, confirming the potential interest of such polyaniline nano-brushes for practical applications.

Computational study of inversion‐topomerization pathways in 1,3‐dimethylcyclohexane and 1,4‐dimethylcyclohexane: Ab initio conformational analysis

AbstractThis work concerns the special conformational behaviors for di‐substituted cyclohexanes that inherently depend on spatial orientations of side chains in flexible cyclic ring. The 1,3‐dimethylcyclohexane and 1,4‐dimethylcyclohexane in both cis‐ and trans‐configurations were focused here to unravel their inversion‐topomerization mechanisms. Full geometry optimizations were separately performed at B3LYP/6‐311++G(d,p) and MP2/6‐311++G(d,p) levels to explicitly identify all distinguishable molecular structures, and thereby the complete interconversion routes were carefully explored. Additional quantum calculations were carried out by G4 and CCSD(T)/6‐311++G(d,p) methods to acquire high‐level single point energies. With respect to quantum results, conformational analysis was conducted to study determinations, thermodynamic stabilities, and relative energies of distinct conformers. Temperature‐dependent populations of local minima for each dimethylcyclohexane were computed by Boltzmann distribution within 300–2500 K. Moreover, their unique inversion and topomerization processes were fully investigated, and potential energy surfaces were illustrated with the rigorous descriptions in two or three‐dimensional schemes for clarify.

Thermally Switchable Molecular Upconversion Emission

In this work a novel strategy is introduced to achieve thermally switchable emission from photon upconversion (UC) systems based on organic dyes. When these molecules were dissolved at low concentrations in phase-change media, a reversible, sharp, and nearly complete interconversion from blue upconverted emission to red luminescence was observed around the solid-to-liquid transition of the system. This result was rationalized in terms of dye aggregation, which selectively occurs in the solid state and dramatically enhances the inter-chromophoric energy transfer processes leading to UC. Notably, this behavior is extendable to different media and dyes, which allows an easy tuning of the switching temperature and emission colors. In addition, with proper selection of the phase-change medium, our strategy permits facile preparation of solid molecular materials showing photon UC at room temperature and even at sub-micromolar dye concentrations.

One amino acid makes the difference: the formation of ent-kaurene and 16α-hydroxy-ent-kaurane by diterpene synthases in poplar.

BackgroundLabdane-related diterpenoids form the largest group among the diterpenes. They fulfill important functions in primary metabolism as essential plant growth hormones and are known to function in secondary metabolism as, for example, phytoalexins. The biosynthesis of labdane-related diterpenes is mediated by the action of class II and class I diterpene synthases. Although terpene synthases have been well investigated in poplar, little is known about diterpene formation in this woody perennial plant species.ResultsThe recently sequenced genome of Populus trichocarpa possesses two putative copalyl diphosphate synthase genes (CPS, class II) and two putative kaurene synthase genes (KS, class I), which most likely arose through a genome duplication and a recent tandem gene duplication, respectively. We showed that the CPS-like gene PtTPS17 encodes an ent-copalyl diphosphate synthase (ent-CPS), while the protein encoded by the putative CPS gene PtTPS18 showed no enzymatic activity. The putative kaurene synthases PtTPS19 and PtTPS20 both accepted ent-copalyl diphosphate (ent-CPP) as substrate. However, despite their high sequence similarity, they produced different diterpene products. While PtTPS19 formed exclusively ent-kaurene, PtTPS20 generated mainly the diterpene alcohol, 16α-hydroxy-ent-kaurane. Using homology-based structure modeling and site-directed mutagenesis, we demonstrated that one amino acid residue determines the different product specificity of PtTPS19 and PtTPS20. A reciprocal exchange of methionine 607 and threonine 607 in the active sites of PtTPS19 and PtTPS20, respectively, led to a complete interconversion of the enzyme product profiles. Gene expression analysis revealed that the diterpene synthase genes characterized showed organ-specific expression with the highest abundance of PtTPS17 and PtTPS20 transcripts in poplar roots.ConclusionsThe poplar diterpene synthases PtTPS17, PtTPS19, and PtTPS20 contribute to the production of ent-kaurene and 16α-hydroxy-ent-kaurane in poplar. While ent-kaurene most likely serves as the universal precursor for gibberellins, the function of 16α-hydroxy-ent-kaurane in poplar is not known yet. However, the high expression levels of PtTPS20 and PtTPS17 in poplar roots may indicate an important function of 16α-hydroxy-ent-kaurane in secondary metabolism in this plant organ.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0647-6) contains supplementary material, which is available to authorized users.

Surface modification of nickel battery electrodes by cobalt plasma immersion ion implantation and deposition

Nickel hydroxide is the electrochemically active material in the positive electrode of several important rechargeable alkalineelectrolyte batteries. It is believed that the Ni2+ in nickel hydroxide is converted to Ni3+ in nickel oxy-hydroxide as the electrode is electrochemically oxidized during the battery charging process, and the reverse reaction (electrochemical reduction) occurs during the battery discharge. However, the details of this process are not completely understood. Because these electrochemical reactions involve surface charge-transfer processes, it is anticipated that the modification of the electrode surface may result in an improved battery performance. We used broad-beam metal ion implantation and the new technique of metal plasma immersion ion implantation and deposition (MePIIID) to add cobalt and other species to the nickel electrode surface. The principle of the latter technique is explained in detail. It has been demonstrated that implanted and deposited cobalt ions (acting as electronic dopants) balance the huge difference in the conductivities of nickel hydroxide and nickel oxy-hydroxide. This beneficial effect promotes a more complete interconversion between the nickel hydroxide and the nickel oxy-hydroxide and leads to a higher capacity and efficiency of the nickel hydroxide electrode in the batteries applications.

Annelated Calixarenes Composed of Calix[4]arenes with Hydroxy Groups in the Endo and Exo Position.

Various phenol-derived calix[4]arenes (3) bearing four hydroxy groups in the exo position have been prepared by uncatalyzed condensation of suitable dimers or tetramers with formaldehyde in xylene in yields up to 44%. The tetra-tert-butyl compound (3a) has been shown by X-ray analysis to adopt a regular cone conformation (nearly identical in shape with the endo isomer) with two intramolecular O-H.O hydrogen bonds, while the corresponding dimer (6c) prefers a conformation (not possible in the calixarene) with two intramolecular O-H.pi(arene) interactions. Condensation of exo-calix[4]arenes 3f,g with free ortho positions (easily available by debutylation) with bisbromomethylated dimers gave annelated double (9) and triple (10) calixarenes consisting of endo- and exo-calix[4]arene substructures in yields up to 24% and 10%, respectively. Molecular dynamics calculations suggest that the exo-calixarene part in 9 is less mobile than the entirely flexible 3, while the endo-calixarene part shows a higher mobility than usual. A complete interconversion cone --> cone is impossible, however, which enables the construction of inherently chiral molecules.

Repriming of L‐type calcium currents revealed during early whole‐cell patch‐clamp recordings in rat ventricular cells.

1. The establishment of the whole-cell patch-clamp recording configuration (WCR) revealed a type of inhibition to which L-type Ca2+ channels were subject in static rat ventricular myocytes before obtaining the WCR. 2. Immediately after membrane disruption (< 10 s), the Ca2+ current (ICa) was absent but gradually increased in amplitude to reach its final waveform (amplitude and kinetics) 2-3 min after the WCR was reached. 3. Three distinct phases (P) were identified. First, no inward but an outward current, blocked (1-2 min) by Cs+ dialysing from the patch pipette (P1), was recorded. Second, overlapping with (P1), ICa increased dramatically to reach a maximum peak amplitude within 2-3 min (P2). Concomitantly, its rate of decay, initially monoexponential and slow, became biexponential owing to the appearance of a fast component of inactivation (P3). Complete interconversion between slow and fast components sometimes occurred. 4. Changes in current waveform were not related to voltage loss or series resistance variation, and suppression of an outward current (P1) was unlikely to account for P2 and P3. 5. The run-up of ICa was independent of the nature of the permeating ions, the membrane holding potential, depolarization, rate of stimulation, the intracellular Ca2+, ATP, Mg2+, Cs+ and the pH of the pipette solution. Since large Ca2+ currents were recorded using the perforated patch technique, the run-up of ICa is not explained by the wash-out of an inhibitory endogenous macromolecule during cell-pipette exchanges. 6. Pharmacological manipulations, including the use of Ca(2+)-Ba(2+)-EGTA and exposure of the cells to isoprenaline and/or Bay K 8644 prior to recording, did not alter the mechanism primarily responsible for build-up. Unrepriming of channel activity was required before these modulations could be effective. 7. Currents could however be instantly augmented when cells were extracellularly superfused during the run-up step. The wash-out of an inhibitory agent originating in the cell itself (such as H+, NH4+ and lactate) and accumulating in the extracellular microenvironment of the cells seems unlikely. Rather, we suggest that pressure-induced mechanostimulation may be involved in the restoration of Ca2+ channel activity.

SPICE2 network thermodynamic simulation of antifolate effects on purine and pyrimidine biosynthesis: Exploring the role of tetrahydrofolate cofactor depletion versus dihydrofolate feedback inhibition

Utilizing the network thermodynamic approach, it is possible to simulate large, nonlinear dynamic systems on SPICE2. For this purpose SPICE2 can become a general systems simulator in spite of the fact that it was originally designed for simulating integrated electrical circuits. As an example of the utility of SPICE2 for large metabolic systems which involve nonlinear kinetics, feedback inhibition of a number of kinds and branching pathways, the cellular folate metabolism scheme is modeled. This scheme is a source of intermediates for de novo purine and pyrimidine metabolism utilized in DNA and RNA synthesis. The action of antifolates that specifically inhibit the enzyme dihydrofolate reductase (DHFR), is simulated in some detail. In particular, the potential of feedback inhibition of secondary sites by dihydrofolate (DHF) polyglutamates that accumulate in the presence of antifolates is modeled to investigate the possible role of such inhibition as opposed, or in addition to, the classical role of tetrahydrofolate (THF) cofactor depletion in the suppression of purine and pyrimidine biosynthesis after blockage of DHFR. The interplay of mathematical modeling, computer simulation, network thermodynamics and experimental observations gave rise to the following conclusions: (1) THF cofactor depletion alone can account for the rapid cessation of purine and pyrimidine synthesis in S-phase cells by antifolates; (2) feedback inhibition by DHF polyglutamates need not be implemented in the mechanism of antifolate inhibition; and (3) the lack of complete interconversion of THF cofactors to DHF does not appear to be related to inhibition of thymidylate synthase by DHF polyglutamates, since this would only slow the accumulation of but not change the final DHF and THF levels in cells with antifolates.

Neutral amino acid transport by membrane vesicles of Streptococcus cremoris is subject to regulation by internal pH

The pH dependence of transport of the neutral amino acids L-serine and L-alanine by membrane vesicles of Streptococcus cremoris have been studied in detail. The rates of four modes of facilitated diffusion (e.g., influx, efflux, exchange, and counterflow) of L-serine and L-alanine increase with increasing H+ concentration. Rates of artificially imposed electrical potential across the membrane (delta psi)-driven transport of L-serine and L-alanine show an optimum at pH 6 to 6.5. Under similar conditions, delta psi- and pH gradient across the membrane (delta pH)-driven transport of L-leucine is observed within the pH range studied (pH 5.5 to 7.5). The effect of ionophores on the uptake of L-alanine and L-serine has been studied in membrane vesicles of S. cremoris fused with proteoliposomes containing beef heart mitochondrial cytochrome c oxidase as a proton motive force (delta p)-generating system (Driessen et al., Proc. Natl. Acad. Sci. USA 82:7555-7559, 1985). An increase in the initial rates of L-serine and L-alanine uptake is observed with decreasing pH, which is not consistent with the pH dependency of delta p. Nigericin, an ionophore that induced a nearly complete interconversion of delta pH into delta psi, stimulated both the rate and the final level of L-alanine and L-serine uptake. Valinomycin, an ionophore that induced a collapse of delta psi with a noncompensating increase in delta pH, inhibited L-alanine and L-serine uptake above pH 6.0 more efficiently than it decreased delta p. Experiments which discriminate between the effects of the internal pH and the driving force (delta pH) on solute transport indicate that at high internal pH the transport systems for L-alanine and L-serine are inactivated. A unique relation exists between the internal pH and the initial rate of uptake of L-serine and L-alanine with an apparent pK of 7.0. The rate of L-alanine and L-serine uptake decreases with increasing internal pH. The apparent complex relation between the delta p and transport of L-alanine and L-serine can be explained by a regulatory effect of the internal pH on the activity of the L-serine and L-alanine carriers.

Cross-reinnervated motor units in cat muscle. I. Flexor digitorum longus muscle units reinnervated by soleus motoneurons.

The properties of flexor digitorum longus (FDL) muscles and of individual motor units were studied in cats 30-50 wk after self-reinnervation by FDL motoneurons (FDL----FDL) or cross-reinnervation by soleus (SOL) motoneurons (SOL----FDL). Individual motor units were functionally isolated by intracellular recording and stimulation of identified SOL alpha-motoneurons. Glycogen-depletion methods permitted histochemical study of muscle fibers belonging to physiologically characterized muscle units. The observations were compared with data from normal cat FDL muscles and motor units (27). Intentionally self-reinnervated FDL muscles (FDL----FDL; n = 5) were normal in size and wet weight. FDL----FDL motor units could be classified into the same physiological categories found in normal FDL [types: fast contracting, fatigable (FF), fast contracting, fatigue resistant (FR), and slow (S); n = 24], with approximately the same proportions as normal. The histochemical muscle fiber types associated with these categories were also qualitatively normal although there was evidence of marked distortion of the normal histochemical mosaic. These data confirm other studies of self-reinnervation and suggest that self-reinnervation can produce complete interconversion of muscle fiber types. Cross-reinnervation of FDL muscle by SOL motoneurons (SOL----FDL; n = 12) produced muscles that were smaller (about half the normal wet weight) and more red than normal. SOL----FDL muscle contracted more slowly than normal or FDL----FDL muscles and had much higher proportions of histochemical type I muscle fibers. In those SOL----FDL muscles, in which little or no unwanted self-reinnervation could be demonstrated, greater than 95% of the muscle fibers were type I. Forty-one individual motor units in SOL----FDL muscles were isolated by intracellular penetration in functionally identified SOL alpha-motoneurons. Their muscle units were all type S by physiological criteria (absence of "sag" in unfused tetani and marked resistance to fatigue). SOL----FDL muscle units had contraction times and fatigue properties that were essentially identical to those of type S units in the normal FDL. All of the seven units, successfully studied by glycogen depletion, exhibited histochemical type I fibers. SOL motoneurons that innervated FDL muscle units had slightly shorter afterhyperpolarization durations than normal SOL cells, but axonal conduction velocities were normal.(ABSTRACT TRUNCATED AT 400 WORDS)

Suggested in vivo irreversible metabolism of labeled cortisol during distribution: effects on kinetic measurements and role of modes and sites of administration.

Radioactively labeled cortisol and cortisone were combined, administered iv to human subjects, and 3α,17,21-trihydroxy-5β-pregnane-11, 20-dione (THE) and 3α,1 10,17,21-tetrahydroxy-5β-pregnan-20-one (THF) were determined from the total urinary radioactive metabolites. The presence of 10–60% more of the cortisone-isotope than the cortisol-isotope in THE than in THF suggested that a large portion of the labeled cortisone was reduced to metabolites without entering the cortisol pool. 14C-cortisol and 3H-cortisone combined were injected into a right antecubital vein over 30 sec and urine was collected each 15 min. THE had high initial 3H/14C values 260% above the value at equilibrium confirming significant formation of labeled THE prior to essentially complete interconversion of labeled cortisone and cortisol. In contrast, 3H/14C of THF was essentially constant from the outset indicating almost complete interconversion before significant labeled THF formed. Thus, it is postulated that a portion of labeled cor...

Interconversion of Cortisol and Cortisone in Man and Its Effect on the Measurement of Cortisol Secretion Rate

ABSTRACT Following intravenous injection of tracer doses of 4-14C-cortisol and 1,2-3H-cortisone, urinary metabolites of cortisone and cortisol were extracted and purified in 3 normal adult subjects, 1 child and 2 adult men treated with ACTH. Study of the 3H/14C ratio in the different metabolites and their specific activity as related to 14C and to 3H showed that there is extensive but not complete interconversion between cortisol and cortisone. Although the data obtained are those expected if cortisol alone was secreted by the adrenal cortex of the subjects studied, the lack of sensitivity of the theoretical model employed did not permit us to exclude cortisone secretion.

Studies on the metabolism of C-19 steroids in the human foeto-placental unit. 2. Metabolism of androstenedione and testosterone in the intact foeto-placental unit.

ABSTRACT 3H-labelled androst-4-ene-3,17-dione and 14C-labelled testosterone were administered at laparotomy into the intact foeto-placental circulation and the principal metabolites present in the placenta and various foetal tissues were isolated and identified. Five subjects were investigated; all foetuses were females. Except in the liver, where there was a complete interconversion, in all tissues more testosterone was converted into androstenedione than vice versa. The following unconjugated (ether soluble) metabolites were isolated: 5β-androstane-3,17-dione from the liver, gastro-intestinal tract and residual foetal tissues; 3α-hydroxy-5β-androstan-17-one (liver, lungs, gastrointestinal tract, residual foetal tissues); 5β-androstane-3α,17β-diol (liver); 5α-androstane-3,17-dione (lungs, gastro-intestinal tract, residual foetal tissues); 3α-hydroxy-5α-androstan-17-one (lungs, gastro-intestinal tract, residual foetal tissues); 11β-hydroxyandrost-4-ene-3,17-dione (adrenals); oestrone (placenta and combined foetal tissues); 17β-oestradiol (placenta); oestriol (placenta). The following metabolites were isolated from the conjugated (water soluble) fraction of the liver: testosterone, 3α-hydroxy-5β-androstan-17-one, 3β-hydroxy-5β-androstan-17-one, 5β-androstane-3α,17β-diol, oestrone, 17β-oestradiol, oestriol. In addition, oestrone was isolated from the aqueous phase of the placentas, oestrone, 17β-oestradiol and oestriol from the aqueous phase of the combined foetal tissues, and 15α-hydroxy-oestradiol was detected and characterized in the extracts of placentas and livers. A high degree of enzymic stereospecificity in the reduction of the administered androstenedione and testosterone was observed in the various foetal tissues: 3α,5β-forms were predominant in the liver, with little, if any 3α,5α-forms present. In the lungs and residual foetal tissues, 3α,5α-products were predominant, whereas in the extracts of the gastrointestinal tract both types of reduction products were present in approximately equal amounts.

METABOLISM OF OESTRONE AND OESTRADIOL IN THE HUMAN FOETO-PLACENTAL UNIT AT MIDPREGNANCY.

ABSTRACT In four cases of therapeutic abortion by laparotomy, tracer amounts of oestrone-6,7-3H and 17β-oestradiol-16-14C were injected into the umbilical vein 20 minutes prior to the interruption of gestation, and the radioactive material recovered from the placenta and various foetal tissues was analysed. More than 92 per cent of the radioactive material recovered from the foetus, but less than 15 per cent of that present in the placenta, was in a conjugated form. Among the foetal tissues studied, the highest percentage of unconjugated (free) radioactive material (25 per cent) occurred in the adrenals. Determination of the isotopic ratios revealed that complete interconversion of injected material was approached only by the oestrone and 17β-oestradiol isolated from the conjugated fraction of the liver. Approximately 10 per cent of the radioactive material recovered from the foetal liver and smaller amounts of that found in the placenta and residual foetal tissues were isolated and identified as oestriol. The isotopic ratio of oestriol isolated from different sources approached very closely that of conjugated oestrone and 17β-oestradiol in the foetal liver, but was distinctly different from the isotopic ratio of free and conjugated oestrone and 17β-oestradiol in all other tissues. At least 9 additional metabolites were detected in the conjugated fraction of the foetal liver. One of them was identified as 15α-hydroxy-17β-oestradiol, another one as 16- (or possibly 17-) epioestriol, and two were ring D ketolic oestrogens, most probably 16α-hydroxyoestrone and 16-oxo-17β-oestradiol. The isotopie ratios of all identified compounds were similar to those of oestrone and 17β-oestradiol isolated from the same fraction. It is concluded that in the foeto-placental unit at midpregnancy, the liver is the main site of oestrone and 17β-oestradiol metabolism and that this metabolism takes place predominantly in a conjugated form, most probably in form of 3-sulphates.