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Femtosecond carrier dynamics in biased AlxGa1-xAs heterostructure diodes is investigated tracing transient modifications of the Franz-Keldysh absorption spectrum. The nonlinear optical response is sensitive to the number of electron-hole pairs in the high-field region of the sample. As a result, the dynamical buildup of a nonequilibrium carrier avalanche due to impact ionization for electric fields F>=350 kV/cm is directly analyzed in the time domain. The time scale of the carrier multiplication is found to be in the order of 10 ps depending on the number of photoinjected carriers. Monte Carlo simulations in a simplified band structure agree well with the experiment. [ABSTRACT FROM AUTHOR]

High-field transport in GaAs is investigated tracing ultrafast modifications of the Franz–Keldysh absorption spectrum of a AlxGa1-xAs heterostructure diode. A sophisticated sample design allows us to isolate the unipolar tranport properties of holes in combination with a nanometer scale definition of layers for both photoexcitation and detection of the propagating carrier distribution. Transient velocities and spatial broadening of the hole ensemble are directly measured for electric fields between 15 and 200 kV/cm comparing room temperature operation to results for TL=4 K. Even at low temperatures, the transient hole velocities are found not to exceed a value of 1.2×107 cm/s which is a result of ultrafast optical phonon emission with a scattering time below 25 fs. [ABSTRACT FROM AUTHOR]

Background: A significant proportion of patients with a depressive disorder show resistance to pharmacological and psychotherapeutic antidepressant treatments. Electroconvulsive therapy (ECT) is still one of the most effective treatment methods, especially in the acute phase. In everyday clinical practice, this usually accompanies pharmacological treatment. It has been shown that pharmacological treatment following acute ECT treatment reduces the rate of relapses. However, the effect of various antidepressants (ADs) and antipsychotics (APs) on the effect during the course of ECT has rarely been investigated., Methods: In this retrospective chart review study, the data of 104 depressive patients treated with ECT were examined. We analyzed the influence of concomitant administration of AD and AP or no psychotropic medication on the effect of ECT using the Montgomery-Åsberg Depression Rating Scale (MADRS). We further analyzed the influence of the ADs Bupropion, Venlafaxine, and Sertraline or no AD and the influence of augmentation with Aripiprazole or Quetiapine or Olanzapine., Results/discussion: Psychotropic medication did not have an impact on antidepressant efficacy of ECT as measured with the MADRS scores. In addition, the comparison between the antidepressant or antipsychotic medications themselves did not show any significant difference. However, we found a significantly different seizure duration depending on the antidepressant substance that patients received during ECT ( p = .008). ECT treatment itself led to a highly significant reduction of 13.3 points in the MADRS ( p <.001)., Conclusion: Taken together, our study underlines that concomitant psychotropic medication while doing electroconvulsive therapy does not bare the risk of prolonged seizure duration or does it reduce the effectiveness of ECT. To the best of our knowledge, this study is the first to examine the effect of treatment with antidepressants in combination with antipsychotics while doing ECT. In light of our results, this combination therapy is safe and effective. Bearing in mind the delay in onset of antidepressant action of medication and the importance of antidepressant medication for relapse prevention, this study further supports the recommendation that psychotropic medication should be given in adjunction to ECT., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Mohamad, Trumm, Treskatsch, Drevs, Bajbouj and Wiedemann.)

Background/objective: Electroconvulsive therapy (ECT) is effective for treatment-resistant and psychotic depression. One previously reported side effect of ECT is the disruption of memory reconsolidation. This study examines whether this disruption induced by ECT can be detected in routine neuropsychological assessments., Methods: In this retrospective study, the Autobiographical Memory Interview (AMI) was applied before and after ECT. Memories of the same events and facts were tested pre and post ECT treatments. 38 patients, receiving ECT for the treatment of unipolar or bipolar depression, were matched for age, sex, and stimulus intensity and divided into two groups: Group A was tested on the day before the first ECT treatment, whereas group B two or more days before., Results: Patients who were tested by AMI on the day before ECT and thus reactivated memorie shortly before the first ECT treatment deteriorated in AMI score. Patients who had at least two days between memory activation and treatment improved regarding the number of recalled memories. Memory impairment was not associated with depression severity., Conclusion: This finding suggests that ECT might be capable of impairing reconsolidation. The study demonstrates that memories of personal events can potentially be affected by ECT within a time interval of 24 h of memory vulnerability after reactivation. Implications for practice and future research are discussed., Competing Interests: The authors have no conflicts of interest to report., (©2023TheAuthors.PublishedbyElsevierB.V.)

Study Objectives: Insomnia is defined by the subjective complaint of poor sleep as well as daytime impairments. Since polysomnography (PSG) typically shows only modest sleep impairment, some still unidentified property of sleep, not mirrored in PSG, may be modified in insomnia.One possible mechanistic hypothesis is that insomnia patients may be more sensitive to inevitably occurring internal or external stimuli during the night, causing brief sleep disruptions then perceived as wake time., Methods: Auditory event-related potentials (ERP) to low intensity (50 dB SPL) synthesized guitar tones played continuously throughout two nights of polysomnographically registered sleep were obtained in fifty patients with insomnia disorder (ID, without comorbidities) and 50 age- and sex-matched good sleeper controls (GSC) for each sleep stage and NREM/REM cycle. Phasic and tonic REM were treated as separate stages. Latencies and amplitudes of components P1, N1 and P2 were measured and analyzed by multivariate repeated-measures ANCOVA including effects of group, night, cycle, and age., Results: ID showed reduced P2 amplitudes relative to GSC specifically in phasic REM sleep. The same reduction also correlated with the amount of sleep misperception across groups. Independent component analysis showed a frontal negativity to contribute most to this group difference., Conclusions: The present finding can be interpreted as increased mismatch negativity (MMN) in ID, reflecting automated detection of change in the auditory system and a concomitant orienting response. Specifically phasic REM sleep appears to be vulnerable to sensory afferences in ID patients, possibly contributing to the perception of being awake., Clinical Trial Information: Short name "PERSLEEP 2," URL https://www.drks.de/drks&#95;web/navigate.do?navigationId=trial.HTML&TRIAL&#95;ID=DRKS00008965, Registration DRKS00008965., (© Sleep Research Society 2021. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Trivalent actinides generally exhibit ninefold coordination in solution. 2,6-Bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (nPr-BTP), a tridentate nitrogen donor ligand, is known to form ninefold coordinated 1:3 complexes, [An(nPr-BTP) 3 ] 3+ (An = U, Pu, Am, Cm) in solution. We report a Cm(III) complex with tenfold coordination in solution, [Cm(nPr-BTP) 3 (NO 3 )] 2+ . This species was identified using time-resolved laser fluorescence spectroscopy (TRLFS), vibronic side band spectroscopy (VSBS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). Adding nitrate to a solution of the [Cm(nPr-BTP) 3 ] 3+ complex in 2-propanol shifts the Cm(III) emission band from 613.1 to 617.3 nm. This bathochromic shift is due to a higher coordination number of the Cm(III) ion in solution, in agreement with the formation of the [Cm(nPr-BTP) 3 (NO 3 )] 2+ complex. The formation of this complex exhibits slow kinetics in the range of 5 to 12 days, depending on the water content of the solvent. Formation of a complex [Cm(nPr-BTP) 3 (X)] 2+ was not observed for anions other than nitrate (X - = NO 2 - , CN - , or OTf - ). The formation of the [Cm(nPr-BTP) 3 (NO 3 )] 2+ complex was studied as a function of NO 3 - and nPr-BTP concentrations, and slope analyses confirmed the addition of one nitrate anion to the [Cm(nPr-BTP) 3 ] 3+ complex. Experiments with varied nPr-BTP concentration show that [Cm(nPr-BTP) 3 (NO 3 )] 2+ only forms at nPr-BTP concentrations below 10 -4 mol/L whereas for concentrations greater than 10 -4 mol/L the formation of the tenfold species is suppressed and [Cm(nPr-BTP) 3 ] 3+ is the only species present. The presence of the tenfold coordinated complex is supported by VSBS, XPS, and DFT calculations. The vibronic side band of the [Cm(nPr-BTP) 3 (NO 3 )] 2+ complex exhibits a nitrate stretching mode not observed in the [Cm(nPr-BTP) 3 ] 3+ complex. Moreover, XPS on [M(nPr-BTP) 3 (NO 3 )](NO 3 ) 2 (M = Eu, Am) yields signals from both non-coordinated and coordinated nitrate. Finally, DFT calculations reveal that the energetically most favored structure is obtained if the nitrate is positioned on the C 2 axis of the D 3 symmetrical [Cm(nPr-BTP) 3 ] 3+ complex with a bond distance of 413 pm. Combining results from TRLFS, VSBS, XPS, and DFT provides sound evidence for a unique tenfold coordinated Cm(III) complex in solution-a novelty in An(III) solution chemistry.

The molecular origin of the selectivity of N-donor ligands, such as alkylated bis-triazinyl pyridines (BTPs), for actinide complexation in the presence of lanthanides is still largely unclear. NMR investigations of an Am(nPrBTP)3(3+) complex with a (15)N labelled ligand showed that it exhibits large differences in (15)N chemical shift for coordinating N-atoms in comparison to both lanthanide(III) complexes and the free ligand. The temperature dependence of NMR chemical shifts observed for this complex indicates a weak paramagnetism. This fact and the observed large chemical shift for bound nitrogen atoms allow us to conclude that metal-ligand bonding in the reported Am(III) N-donor complex has a larger share of covalence than in lanthanide complexes. This may account for the observed selectivity.

The present work focuses on highly selective ligands for An(III)/Ln(III) separation: bis(triazinyl)bipyridines (BTBPs). By combining time-resolved laser-induced fluorescence spectroscopy, nanoelectrospray ionization mass spectrometry, vibronic sideband spectroscopy, and X-ray diffraction, we obtain a detailed picture of the structure and stoichiometry of the first coordination sphere of Eu(III)-BTBP complexes in an octanolic solution. The main focus is on the 1:2 complexes because extraction studies revealed that those are the species extracted into the organic phase. The investigations on europium(III) complexes of BTBP with different triazin alkylation revealed differences in the formed complexes due to the bulkiness of the ligands. Because of the vibronic sidebands in the fluorescence spectra, we were able to detect whether or not nitrate ligands are coordinated in the first coordination sphere of the Eu-BTBP complexes. In solution, less sterically demanding BTBP offers enough space for additional coordination of anions and/or solvent molecules to form 9-coordinated Eu-BTBP 1:2 complexes, while bulkier ligands tend to form 8-fold-coordinated structures. We also report the first crystal structure of a Ln-BTBP 1:2 complex and that of its 1:1 complex, both of which are 10-coordinated.

The complexation of Cm(III) and Eu(III) with 4-t-butyl-6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (t-Bu-C2-BTBP) in water/2-propanol solution is studied. With increasing ligand concentration, 1 : 2 complexes [M(t-Bu-C2-BTBP)(2)(H(2)O)](3+) form from the solvated metal ions. The stability constants are log K(Cm(III)) = 11.1 and log K(Eu(III)) = 9.0. For both Cm(III) and Eu(III), the complexation reaction is both enthalpy and entropy driven. DeltaH(Cm(III)) is 11.7 kJ mol(-1) more negative than DeltaH(Eu(III)), whereas the entropy difference is negligible. This is in good agreement with t-Bu-C2-BTBP's selectivity in liquid-liquid extraction.

Two naturally occurring lignanolides, isolated from the tropical climbing shrub Ipomoea cairica, (-)-arctigenin and (-)-trachelogenin, were found to inhibit strongly replication of human immunodeficiency virus type 1 (HIV-1; strain HTLV-III B) in vitro. At a concentration of 0.5 microM, (-)-arctigenin and (-)-trachelogenin inhibited the expression of HIV-1 proteins p17 and p24 by 80-90% and 60-70%, respectively. The reverse transcriptase activity in the culture fluids was reduced by 80-90% when the cells (HTLV-III B/H9) were cultivated in the presence of 0.5 microM (-)-arctigenin or 1 microM (-)-trachelogenin. At the same concentrations, the formation of syncytia in the HTLV-III B/H9-Jurkat cell system was inhibited by the compounds by more than 80%. A series of other lignan type compounds displayed no anti-HIV activity. Studying the molecular mechanism of action of (-)-arctigenin and (-)-trachelogenin we found that both compounds are efficient inhibitors of the nuclear matrix-associated DNA topoisomerase II activity, particularly of the enzyme from HIV-1-infected cells. Our results suggest that both compounds prevent the increase of topoisomerase II activity, involved in virus replication, after infection of cells with HIV-1.