Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.     

Two‐Dimensional Perovskite Oxynitride K2LaTa2O6N with an H+/K+ Exchangeability in Aqueous Solution Forming a Stable Photocatalyst for Visible‐Light H2 Evolution

Undoped layered oxynitrides have not been considered as promising H₂‐evolution photocatalysts because of the low chemical stability of oxynitrides in aqueous solution. Here, we demonstrate the synthesis of a new layered perovskite oxynitride, K₂LaTa₂O₆N, as an exceptional example of a water‐tolerant photocatalyst for H₂ evolution under visible light. The material underwent in‐situ H⁺/K⁺ exchange in aqueous solution while keeping its visible‐light‐absorption capability. Protonated K₂LaTa₂O₆N, modified with an Ir cocatalyst, exhibited excellent catalytic activity toward H₂ evolution in the presence of I^? as an electron donor and under visible light; the activity was six times higher than Pt/ZrO₂/TaON, one of the best‐performing oxynitride photocatalysts for H₂ evolution. Overall water splitting was also achieved using the Ir‐loaded, protonated K₂LaTa₂O₆N in combination with Cs‐modified Pt/WO₃ as an O₂ evolution photocatalyst in the presence of an I₃^?/I^? shuttle redox couple.     

Double‐Decker Paramagnetic {(K)(H3Hhp)2}⋅2− Radical Dianions Comprising Two [30]Trithia‐2,3,5,10,12,13,15,20,22,23,25,30‐Dodecaazahexaphyrins and a Potassium Ion

Reduction of free‐base [30]trithia‐2,3,5,10,12,13,15,20,22,23,25,30‐dodecaazahexaphyrin (H₃Hhp) yields {cryptand[2.2.2](K)}₂{(K)(H₃Hhp)₂}?4C₆H₄Cl₂ ( 1 ) containing double‐decker {(K)(H₃Hhp)₂} ^{? 2?} radical dianions, whose structure was elucidated using X‐ray diffraction. Potassium ion forms 12 short (K⁺)???N(H₃Hhp) contacts with two H₃Hhp macrocycles in the 3.048–3.157 Å range. Dianions have S=1/2 spin state manifesting an effective magnetic moment of 1.64 μ_B at 300 K and a narrow Lorentzian electron paramagnetic resonance signal. Quantum chemical calculations support the ionic nature of the (K⁺)‐N(H₃Hhp) interactions and the nearly equal distribution of the ?1.5 charge over each macrocycle. H₃Hhp takes the role of an aza‐crown ether in free‐base reduced state and forms a new type of double‐decker complex.     

Excited‐State Dynamics of Pentacene Derivatives with Stable Radical Substituents

The excited‐state dynamics of pentacene derivatives with stable radical substituents were evaluated in detail through transient absorption measurements. The derivatives showed ultrafast formation of triplet excited state(s) in the pentacene moiety from a photoexcited singlet state through the contributions of enhanced intersystem crossing and singlet fission. Detailed kinetic analyses for the transient absorption data were conducted to quantify the excited‐state characteristics of the derivatives.     

Synthesis of 7,8‐Dehydropurpurin Dimers and Their Conversion into Conformationally Constrained β‐to‐β Vinylene‐Bridged Porphyrin Dimers

7,8‐Dehydropurpurin has attracted much attention owing to the dual 18π‐ and 20π‐electron circuits in its macrocyclic conjugation. The two‐fold Pd‐catalyzed [3+2] annulation of meso‐bromoporphyrin with 1,4‐diphenylbutadiyne furnished 7,8‐dehydropurpurin dimers. The 8^a,8^a‐linked dimer displays a red‐shifted and enhanced absorption band in the NIR region and a small electrochemical HOMO–LUMO band gap as a consequence of efficient conjugation between the two coplanar 7,8‐dehydropurpurin units. Treatment of this dimer with N‐bromosuccinimide in chloroform and ethanol gave β‐to‐β vinylene‐bridged porphyrin dimers. Owing to the highly constrained conformations, these dimers exhibit perturbed absorption spectra, small Stokes shifts, and high fluorescence quantum yields.     

Tailoring of Deep‐Red Luminescence in Ca2SiO4:Eu2+

We report a new dicalcium silicate phosphor, Ca_2?xEu_xSiO₄, which emits red light in response to blue‐light excitation. When excited at 450 nm, deep‐red emission at 650 nm was clearly observed in Ca_1.2Eu_0.8SiO₄, the external and internal quantum efficiencies of which were 44 % and 50 %, respectively. The red emission from Ca_2?xEu_xSiO₄ was strongly related to the peculiar coordination environments of Eu²⁺ in two types of Ca sites. The red‐emitting Ca₂SiO₄:Eu²⁺ phosphors are promising materials for next‐generation, white‐light‐emitting diode applications.     

Multicolour Fluorescent Memory Based on the Interaction of Hydroxy Terphenyls with Fluoride Anions

Memory operations based on variation of a molecule’s properties are important because they may lead to device miniaturization to the molecular scale or increasingly complex information processing protocols beyond the binary level. Molecular memory also introduces possibilities related to information‐storage security where chemical information (or reagents) might be used as an encryption key, in this case, acidic/basic reagents. Chemical memory that possesses both volatile and non‐volatile functionality requires reversible conversion between at least two chemically different stable or quasi‐stable states. Here we have developed the phenol–phenoxide equilibrium of phenol fluorophores as a data storage element, which can be used to write or modulate data using chemical reagents. The properties of this system allow data to be stored and erased either in non‐volatile or volatile modes. We also demonstrate non‐binary switching of states made possible by preparation of  a composite containing the molecular memory elements.     

MALDI-Q-TOF mass spectrometric determination of gold and platinum in tissues using their diethyldithiocarbamate chelate complexes

A rapid determination method is presented for gold (Au³⁺) and platinum (Pt⁴⁺) in tissues using matrix-assisted laser desorption ionization quadrupole time-of-flight mass spectrometry (MALDI-Q-TOF-MS). Au and Pt ions in wet-ashed tissue solution were reacted with diethyldithiocarbamate (DDC), and the resulting chelate complex ions Au(DDC)₂ ⁺ and Pt(DDC)₃ ⁺ were detected by MALDI-Q-TOF-MS using α-cyano-4-hydroxycinnamic acid as a matrix. The limit of detection (LOD) was 0.8 ng/g tissue and the quantification range was 2–400 ng/g for Au, and the LOD was 6 ng/g tissue and the quantification range was 20–4,000 ng/g for Pt. The Pt levels detected by MALDI-Q-TOF-MS in several tissues of a patient overdosed with cisplatin were nearly the same as those detected by flow-injection electrospray ionization mass spectrometry. The LODs of Au and Pt were 0.04 pg per well (sample spot) and 0.3 pg per well, respectively. To our knowledge, this is the first attempt to quantify Au³⁺ and Pt⁴⁺ ions in tissues by MALDI-Q-TOF-MS.

An integrated cutting stock and sequencing problem

In this paper an integrated problem formulated as an integer linear programming problem is presented to find an optimal solution to the cutting stock problem under particular pattern sequencing constraints. The solution uses a Lagrangian approach. The dual problem is solved using a modified subgradient method. A heuristic for the integrated problem is also presented. The computational results obtained from a set of unidimensional instances that use these procedures are reported.