Vision of nuclear physics with photo-nuclear reactions by laser-driven $\sf \gamma$ beams

A laser-accelerated dense electron sheet with an energy \(E=\tilde{\gamma} mc^2\) can be used as a relativistic mirror to coherently reflect a second laser with photon energy ?ω, thus generating by the Doppler boost [A. Einstein, Annalen der Physik 17, 891 (1905); D. Habs et al., Appl. Phys. B 93, 349 (2008)] brilliant high-energy photon beams with \(\hbar\omega^{\prime}=4\tilde{\gamma}^2\hbar\omega\) and short duration for many new nuclear physics experiments.While the shortest-lived atomic levels are in the atto-second range, nuclear levels can have lifetimes down to zeptoseconds. We discuss how the modulation of electron energies in phase-locked laser fields used for as-measurements [E. Goulielmakis et al., Science 317, 769 (2007)] can be carried over to the new direct measurement of fs–zs nuclear lifetimes by modulating the energies of accompanying conversion electrons or emitted protons. In the field of nuclear spectroscopy we discuss the new perspective as a function of increasing photon energy. In nuclear systems a much higher sensitivity is predicted to the timevariation of fundamental constants compared to atomic systems [V. Flambaum, arXiv:nucl-th/0801.1994v1 (2008)]. For energies up to 50 keV Mössbauer-like recoilless absorption allows to produce nuclear bosonic ensembles with many delocalized coherent polaritons [G.V. Smirnov et al., Phys. Rev. A 71, 023804 (2005)] for the firsttime. Using the (γ,n) reaction to produce cold, polarized neutrons with a focusing ellipsoidal device [P. Böni, Nucl. Instrum. Meth. A 586, 1 (2008); Ch. Schanzer et al., Nucl. Instrum. Meth. 529, 63 (2004)], brilliant cold polarized micro-neutron beams become available. The compact and relatively cheap laser-generated γ beams may serve forextended studies at university-based facilities.     

Combination therapy with normobaric oxygen (NBO) plus thrombolysis in experimental ischemic stroke

Background  

The widespread use of tissue plasminogen activator (tPA), the only FDA-approved acute stroke treatment, remains limited by its narrow therapeutic time window and related risks of brain hemorrhage. Normobaric oxygen therapy (NBO) may be a useful physiological strategy that slows down the process of cerebral infarction, thus potentially allowing for delayed or more effective thrombolysis. In this study we investigated the effects of NBO started simultaneously with intravenous tPA, in spontaneously hypertensive rats subjected to embolic middle cerebral artery (MCA) stroke. After homologous clot injection, animals were randomized into different treatment groups: saline injected at 1 hour; tPA at 1 hour; saline at 1 hour plus NBO; tPA at 1 hour plus NBO. NBO was maintained for 3 hours. Infarct volume, brain swelling and hemorrhagic transformation were quantified at 24 hours. Outcome assessments were blinded to therapy.     

Über die algebraischen Gleichungen,deren Wurzeln in einem Kreise oder in einer Halbebene liegen

Ohne Zusammenfassung     

Formation of Foam‐like Microstructural Carbon Material by Carbonization of Porous Coordination Polymers through a Ligand‐Assisted Foaming Process

Porous carbon material with a foam‐like microstructure has been synthesized by direct carbonization of porous coordination polymer (PCP). In situ generation of foaming agents by chemical reactions of ligands in PCP during carbonization provides a simple way to create lightweight carbon material with a foam‐like microstructure. Among several substituents investigated, the nitro group has been shown to be the key to obtain the unique foam‐like microstructure, which is due to the fast kinetics of gas evolution during carbonization. Foam‐like microstructural carbon materials showed higher pore volume and specific capacitance compared to a microporous carbon.     

KINETIC STUDIES ON THE ACID-CATALYZED PUMMERER REACTION OF α-(METHYLSULFINY)ACETOPHENONES

Abstract

The kinetic behavior of the acid-catalyzed Pummerer reaction of α-(methylsulfinyl)acetophenones in dilute hydrochloric acid has been studied in detail. The kinetic data were analyzed in the light of correlations between the reaction rates and acidity functions, activation parameters, solvent isotope effects, polar effects of substituents, etc. Moreover, ¹⁸O-tracer experiments were also carried out using acid media containing H₂ ¹⁸O. Based on these observations, a plausible mechanism for this reaction has been discussed.     

Synthesis, characterization, and solvent-independent photochromism of spironaphthooxazine dimers

Specifically angled, conjugated spiroindolinonaphthooxazine dimers (SNOD) have been synthesized. The photochromic reactions of two types of SNOD were studied under continuous UV irradiation in solvents of different polarity. Comparison of these results with the single unit provides the examination of the specific effect of substituents on their photochromic properties and relaxation kinetics. The photomerocyanine isomers showed positive solvatochromism, supporting the premise for a less polar quinoidal structure. The thermal closing rate at 25 °C ranged from 0.2 to 1.6 s⁻¹ depending on the compound and solvent. Photochromism of these new compounds showed little dependency on solvent polarity and stable cyclability.     

Hybrid Mesoporous-Silica Materials Functionalized by PtII Complexes: Correlation between the Spatial Distribution of the Active Center,Photoluminescence Emission,and Photocatalytic Activity

[Pt(tpy)Cl]Cl (tpy: terpyridine) was successfully anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl)triethoxysilane with the aim of developing new inorganic–organic hybrid photocatalysts. Herein, the relationship between the luminescence characteristics and photocatalytic activities of these materials is examined as a function of Pt loading to define the spatial distribution of the Pt complex in the mesoporous channel. At low Pt loading, the Pt complex is located as an isolated species and exhibits strong photoluminescence emission at room temperature owing to metal-to-ligand charge-transfer (³MLCT) transitions (at about 530 nm). Energy- and/or electron-transfer from ³MLCT to O₂ generate potentially active oxygen species, which are capable of promoting the selective photooxidation of styrene derivatives. On the other hand, short Pt⋅⋅⋅Pt interactions are prominent at high loading and the metal-metal-to-ligand charge-transfer (³MMLCT) transition is at about 620 nm. Such Pt complexes, which are situated close to each other, efficiently catalyze H₂-evolution reactions in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light irradiation. This study also investigates the effect of nanoconfinement on anchored guest complexes by considering the differences between the pore dimensions and structures of mesoporous-silica materials.     

Simple Routes 5-Alkylamino-p-Menthene

The reactions of metalated aldimine with electrophiles have been widely used for the purpose of synthesis of several natural products^1-3). In this communication, we wish to report simple synthetic methods for 5-alkylamino-p-menthene (1) using the metalated aldimine.