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1.
Nature ; 616(7958): 696-701, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-37046087

RESUMO

Strong light fields have created opportunities to tailor novel functionalities of solids1-5. Floquet-Bloch states can form under periodic driving of electrons and enable exotic quantum phases6-15. On subcycle timescales, lightwaves can simultaneously drive intraband currents16-29 and interband transitions18,19,30,31, which enable high-harmonic generation16,18,19,21,22,25,28-30 and pave the way towards ultrafast electronics. Yet, the interplay of intraband and interband excitations and their relation to Floquet physics have been key open questions as dynamical aspects of Floquet states have remained elusive. Here we provide this link by visualizing the ultrafast build-up of Floquet-Bloch bands with time-resolved and angle-resolved photoemission spectroscopy. We drive surface states on a topological insulator32,33 with mid-infrared fields-strong enough for high-harmonic generation-and directly monitor the transient band structure with subcycle time resolution. Starting with strong intraband currents, we observe how Floquet sidebands emerge within a single optical cycle; intraband acceleration simultaneously proceeds in multiple sidebands until high-energy electrons scatter into bulk states and dissipation destroys the Floquet bands. Quantum non-equilibrium calculations explain the simultaneous occurrence of Floquet states with intraband and interband dynamics. Our joint experiment and theory study provides a direct time-domain view of Floquet physics and explores the fundamental frontiers of ultrafast band-structure engineering.

2.
Nature ; 610(7931): 290-295, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36224421

RESUMO

Delocalized Bloch electrons and the low-energy correlations between them determine key optical1, electronic2 and entanglement3 functionalities of solids, all the way through to phase transitions4,5. To directly capture how many-body correlations affect the actual motion of Bloch electrons, subfemtosecond (1 fs = 10-15 s) temporal precision6-15 is desirable. Yet, probing with attosecond (1 as = 10-18 s) high-energy photons has not been energy-selective enough to resolve the relevant millielectronvolt-scale interactions of electrons1-5,16,17 near the Fermi energy. Here, we use multi-terahertz light fields to force electron-hole pairs in crystalline semiconductors onto closed trajectories, and clock the delay between separation and recollision with 300 as precision, corresponding to 0.7% of the driving field's oscillation period. We detect that strong Coulomb correlations emergent in atomically thin WSe2 shift the optimal timing of recollisions by up to 1.2 ± 0.3 fs compared to the bulk material. A quantitative analysis with quantum-dynamic many-body computations in a Wigner-function representation yields a direct and intuitive view on how the Coulomb interaction, non-classical aspects, the strength of the driving field and the valley polarization influence the dynamics. The resulting attosecond chronoscopy of delocalized electrons could revolutionize the understanding of unexpected phase transitions and emergent quantum-dynamic phenomena for future electronic, optoelectronic and quantum-information technologies.

3.
Phys Rev Lett ; 128(24): 247401, 2022 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-35776456

RESUMO

The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding GaAs/AlGaAs quantum wells are studied directly within their band structure using a noncollinear pump-probe geometry with phase-stable midinfrared pulses. Selective excitation of the lower polariton at a frequency of ∼25 THz and at a finite in-plane momentum k_{‖} leads to the emergence of a narrowband maximum in the probe reflectivity at k_{‖}=0. A quantum mechanical model identifies the underlying microscopic process as stimulated coherent polariton-polariton scattering. These results mark an important milestone toward quantum control and bosonic lasing in custom-tailored polaritonic systems in the mid and far infrared.

4.
Arch Biochem Biophys ; 726: 109233, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35659493

RESUMO

Some chemical properties of cystine and cysteine have been compared with those of their selenium-containing analogs. Major differences were noted between their titration curves, pK values of 2.01, 5.24, and 9.96 were observed for the ionizations of the carboxyl, selenohydryl, and amino groups, respectively, of selenocysteine. These values are compared with a pK of 2.3 for the carboxyl group of cysteine and values in the range of 8-10 for the ionization of the sulfhydryl and amino groups. Selenocysteine is much more reactive with halo acid derivatives than is cysteine, and reacts readily with iodoacetate even at pH values much below the pK of the selenohydryl group. Selenocysteine has an apparent half-wave potential of -0.212 V compared with 0.021 V for cysteine. It is unstable to acid hydrolysis, being completely decomposed by heating at 110° in 6 n HCl. It is also more soluble in water than is cysteine.


Assuntos
Selênio , Selenocisteína , Cisteína , Cistina/análogos & derivados , Compostos Organosselênicos , Selênio/química , Enxofre
5.
Nat Commun ; 13(1): 3220, 2022 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-35680873

RESUMO

Tunable electromagnets and corresponding devices, such as magnetic lenses or stigmators, are the backbone of high-energy charged particle optical instruments, such as electron microscopes, because they provide higher optical power, stability, and lower aberrations compared to their electric counterparts. However, electromagnets are typically macroscopic (super-)conducting coils, which cannot generate swiftly changing magnetic fields, require active cooling, and are structurally bulky, making them unsuitable for fast beam manipulation, multibeam instruments, and miniaturized applications. Here, we present an on-chip microsized magnetic charged particle optics realized via a self-assembling micro-origami process. These micro-electromagnets can generate alternating magnetic fields of about ±100 mT up to a hundred MHz, supplying sufficiently large optical power for a large number of charged particle optics applications. That particular includes fast spatiotemporal electron beam modulation such as electron beam deflection, focusing, and wave front shaping as required for stroboscopic imaging.

6.
Sci Rep ; 12(1): 631, 2022 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-35022446

RESUMO

Polyethylene (C2H4)n was compressed to pressures between 10 and 30 GPa in a diamond anvil cell (DAC) and laser heated above 2500 K for approximately one second. This resulted in the chemical decomposition of the polymer into carbon and hydrocarbon reaction products. After quenching to ambient temperature, the decomposition products were measured in the DAC at pressures ranging from ambient to 29 GPa using a combination of x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). XRD identified cubic diamond and methane as the predominant product species with their pressure-volume relationships exhibiting strong correlations to the diamond and methane equations of state. Length scales associated with the diamond products, obtained from SAXS measurements, indicate the formation of nanodiamonds with a radius of gyration between 12 and 35 nm consistent with 32-90 nm diameter spherical particles. These results are in good agreement with the predicted product composition under thermodynamic and chemical equilibrium.

7.
Prog Neurobiol ; 209: 102208, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34923049

RESUMO

Sleep disorders have been linked to alterations of gut microbiota composition in adult humans and animal models, but it is unclear how this link develops. With longitudinal assessments in 162 healthy infants, we present a so far unrecognized sleep-brain-gut interrelationship. First, we report a link between sleep habits and gut microbiota: daytime sleep is associated with bacterial diversity, and nighttime sleep fragmentation and variability are linked with bacterial maturity and enterotype. Second, we demonstrate a sleep-brain-gut link: bacterial diversity and enterotype are associated with sleep neurophysiology. Third, we show that the sleep-brain-gut link is relevant in development: sleep habits and bacterial markers predict behavioral-developmental outcomes. Our results demonstrate the dynamic interplay between sleep, gut microbiota, and the maturation of brain and behavior during infancy, which aligns with the newly emerging concept of a sleep-brain-gut axis. Importantly, sleep and gut microbiota represent promising health targets since both can be modified non-invasively. As many adult diseases root in early childhood, leveraging protective factors of adequate sleep and age-appropriate gut microbiota in infancy could constitute a health promoting factor across the entire human lifespan.


Assuntos
Microbioma Gastrointestinal , Animais , Encéfalo , Pré-Escolar , Humanos , Sono
8.
Light Sci Appl ; 10(1): 246, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34924564

RESUMO

The exploitation of ultrafast electron dynamics in quantum cascade lasers (QCLs) holds enormous potential for intense, compact mode-locked terahertz (THz) sources, squeezed THz light, frequency mixers, and comb-based metrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operational THz QCLs. Here, we employ high-field THz pulses to perform the first ultrafast two-dimensional spectroscopy of a free-running THz QCL. Strong incoherent and coherent nonlinearities up to eight-wave mixing are detected below and above the laser threshold. These data not only reveal extremely short gain recovery times of 2 ps at the laser threshold, they also reflect the nonlinear polarization dynamics of the QCL laser transition for the first time, where we quantify the corresponding dephasing times between 0.9 and 1.5 ps with increasing bias currents. A density-matrix approach reproducing the emergence of all nonlinearities and their ultrafast evolution, simultaneously, allows us to map the coherently induced trajectory of the Bloch vector. The observed high-order multi-wave mixing nonlinearities benefit from resonant enhancement in the absence of absorption losses and bear potential for a number of future applications, ranging from efficient intracavity frequency conversion, mode proliferation to passive mode locking.

9.
Nat Commun ; 12(1): 5202, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34471110

RESUMO

Benzene (C6H6), while stable under ambient conditions, can become chemically reactive at high pressures and temperatures, such as under shock loading conditions. Here, we report in situ x-ray diffraction and small angle x-ray scattering measurements of liquid benzene shocked to 55 GPa, capturing the morphology and crystalline structure of the shock-driven reaction products at nanosecond timescales. The shock-driven chemical reactions in benzene observed using coherent XFEL x-rays were a complex mixture of products composed of carbon and hydrocarbon allotropes. In contrast to the conventional description of diamond, methane and hydrogen formation, our present results indicate that benzene's shock-driven reaction products consist of layered sheet-like hydrocarbon structures and nanosized carbon clusters with mixed sp2-sp3 hybridized bonding. Implications of these findings range from guiding shock synthesis of novel compounds to the fundamentals of carbon transport in planetary physics.

10.
Nature ; 593(7859): 385-390, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34012087

RESUMO

When intense lightwaves accelerate electrons through a solid, the emerging high-order harmonic (HH) radiation offers key insights into the material1-11. Sub-optical-cycle dynamics-such as dynamical Bloch oscillations2-5, quasiparticle collisions6,12, valley pseudospin switching13 and heating of Dirac gases10-leave fingerprints in the HH spectra of conventional solids. Topologically non-trivial matter14,15 with invariants that are robust against imperfections has been predicted to support unconventional HH generation16-20. Here we experimentally demonstrate HH generation in a three-dimensional topological insulator-bismuth telluride. The frequency of the terahertz driving field sharply discriminates between HH generation from the bulk and from the topological surface, where the unique combination of long scattering times owing to spin-momentum locking17 and the quasi-relativistic dispersion enables unusually efficient HH generation. Intriguingly, all observed orders can be continuously shifted to arbitrary non-integer multiples of the driving frequency by varying the carrier-envelope phase of the driving field-in line with quantum theory. The anomalous Berry curvature warranted by the non-trivial topology enforces meandering ballistic trajectories of the Dirac fermions, causing a hallmark polarization pattern of the HH emission. Our study provides a platform to explore topology and relativistic quantum physics in strong-field control, and could lead to non-dissipative topological electronics at infrared frequencies.

11.
BMC Geriatr ; 21(1): 287, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933014

RESUMO

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is a threat to ongoing clinical trials necessitating regular face-to-face, in-person meetings, particularly in participants with a high risk of complications. Guidance on how to handle and safely continue such trials is lacking. Chronically ill elderly individuals require-in addition to protection from infection-regular physical exercise and social contact to remain healthy. Solutions on how to handle these conflicting necessities are needed. The ENTAIER-randomised controlled trial was investigating the influence of mindful movements on fall risk, fear of falling, mobility, balance, life quality, and other outcomes. The study population was planned to comprise of 550 chronically ill elderly individuals with a high risk of falling. The movements were regularly performed in coached groups over 6 months. After the trial began, COVID-19 lockdowns stopped all in-person meetings, and it was expected that the limitations of this pandemic would continue for a long term. Therefore, the exercise programme, which involved complex movements and was typically conducted face-to-face in groups, had to be substituted by a telemedicine programme within a short timeframe. The objectives, therefore, were to identify challenges and tasks that could to be resolved and steps that could to be taken to achieve high-quality, efficacy, safety, and enable human encounter and motivation. METHODS: We proceeded with four steps: 1) A literature review on the quality and feasibility issues of telemedicine in general, and specifically, in exercise training in elderly individuals. 2) Participation in two international telemedicine task forces on integrative medicine, particularly, mind-body medicine. 3) Interviews with study therapists, (for practical purposes, eurythmy therapists and Tai Chi teachers are summarized here as therapists) personnel, and international experts on providing mindful movement exercises and other physiotherapies via live telecommunication technology, and with scientists and patient representatives. 4) Final evaluation by the core trial team and subsequent planning and implementation of changes in the trial organisation. RESULTS: Various tasks and challenges were identified: for the technical equipment for therapists and patients; for the ability of therapists and trial participants to adequately manage the technology and telemedicine intervention; the reservations and concerns about the technology among therapists and participants; safety and data protection in using the technology; and study design. The two major options found on how to continue the trial in the COVID-19 situation were a complete switch to telemedicine and a partial switch in the form of risk management implemented into the former design. CONCLUSIONS: The management of an ongoing clinical trial in a national or international crisis with a minimum of available time and extra financial resources, alongside with two checklists on steps and procedures for trial continuation and telemedicine implementation, may be informative for other researchers or healthcare providers faced with similar challenges and making similar decisions in the current situation or similar future scenarios. TRAIL REGISTRATION: www.drks.de . DRKS00016609. Registered July 30, 2019.


Assuntos
Acidentes por Quedas , COVID-19 , Idoso , Controle de Doenças Transmissíveis , Terapia por Exercício , Medo , Humanos , SARS-CoV-2
12.
Phys Rev Lett ; 126(17): 177404, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33988443

RESUMO

We explore the nonlinear response of tailor-cut light-matter hybrid states in a novel regime, where both the Rabi frequency induced by a coherent driving field and the vacuum Rabi frequency set by a cavity field are comparable to the carrier frequency of light. In this previously unexplored strong-field limit of ultrastrong coupling, subcycle pump-probe and multiwave mixing nonlinearities between different polariton states violate the normal-mode approximation while ultrastrong coupling remains intact, as confirmed by our mean-field model. We expect such custom-cut nonlinearities of hybridized elementary excitations to facilitate nonclassical light sources, quantum phase transitions, or cavity chemistry with virtual photons.

13.
J Eur Acad Dermatol Venereol ; 35(5): 1203-1211, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33336462

RESUMO

BACKGROUND: Hidradenitis suppurativa (HS) is not a well-studied or easily treated disease. Genetic information is essential for advances in the understanding and treatment of HS. This study aims to examine mutations in the gamma-secretase complex, the Notch signalling pathway and to perform a Mendelian analysis of genetic variants that segregated with disease in a full exome sequencing of 11 families with HS. METHOD: Whole-exome sequencing and Mendelian analysis of 11 families with HS from Denmark. Patients with a clinical diagnosis of active HS and a positive family history of HS were recruited. Consenting family members were enrolled and examined for HS as well. We included 11 families, with a total of 51 participants, 24 with HS and 27 without. Whole-exome sequencing using HiSeq platform as paired-end 2 × 150 bases was used. RESULTS: We found mutations in the Notch pathway for all families. We found mutations in the PSENEN and APH1B of the gamma-secretase genes. We also report 161 variants of unknown significance that segregated with the disease within these families. CONCLUSIONS: We did not find causative mutation for each family in this study, supporting the theory that HS is rarely caused by single-gene mutations. We suggest that future genetic studies should be focused on genome-wide association with thousands of cases, as this technique is better suited for suspected polygenic diseases.


Assuntos
Hidradenite Supurativa , Secretases da Proteína Precursora do Amiloide/genética , Exoma/genética , Estudo de Associação Genômica Ampla , Hidradenite Supurativa/genética , Humanos , Proteínas de Membrana/genética , Sequenciamento do Exoma
14.
Science ; 370(6521): 1204-1207, 2020 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-33273100

RESUMO

Searching for quantum functionalities requires access to the electronic structure, constituting the foundation of exquisite spin-valley-electronic, topological, and many-body effects. All-optical band-structure reconstruction could directly connect electronic structure with the coveted quantum phenomena if strong lightwaves transported localized electrons within preselected bands. Here, we demonstrate that harmonic sideband (HSB) generation in monolayer tungsten diselenide creates distinct electronic interference combs in momentum space. Locating these momentum combs in spectroscopy enables super-resolution tomography of key band-structure details in situ. We experimentally tuned the optical-driver frequency by a full octave and show that the predicted super-resolution manifests in a critical intensity and frequency dependence of HSBs. Our concept offers a practical, all-optical, fully three-dimensional tomography of electronic structure even in microscopically small quantum materials, band by band.

15.
Sci Adv ; 6(47)2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33219030

RESUMO

Electron interferometry via phase-contrast microscopy, holography, or picodiffraction can provide a direct visualization of the static electric and magnetic fields inside or around a material at subatomic precision, but understanding the electromagnetic origin of light-matter interaction requires time resolution as well. Here, we demonstrate that pump-probe electron diffraction with all-optically compressed electron pulses can capture dynamic electromagnetic potentials in a nanophotonic material with sub-light-cycle time resolution via centrosymmetry-violating Bragg spot dynamics. The origin of this effect is a sizable quantum mechanical phase shift that the electron de Broglie wave obtains from the oscillating electromagnetic potentials within less than 1 fs. Coherent electron imaging and scattering can therefore reveal the electromagnetic foundations of light-matter interaction on the level of the cycles of light.

16.
BMC Geriatr ; 20(1): 108, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32183768

RESUMO

BACKGROUND: In elderly poeple, multimorbidity and polypharmacy increase while sensory, motor and cognitive functions decrease. Falls occur in 30% of people aged 65 years and older at least once per year, with injuries at 10-20%. Reducing falls and enhancing physical, emotional and cognitive capacities are essential for healthy aging despite chronic disease. Eurythmy therapy (EYT) and Tai Chi train balance, mobility and concentrative and sensory capacities. METHODS: In eight trial sites (academic or community hospitals), 550 outpatients aged 65 years and older with chronic disease and increased risk of falling (history of imbalance, Berg Balance Scale (BBS) score ≤ 49) will be randomly assigned (1:1:1) to receive either EYT or Tai Chi (each provided in one-hour group sessions, twice, later once per week plus practice at home, for over 24 weeks) added to standard care or standard care alone. Standard care includes a detailed written recommendation on fall prevention and the visit of a primary care doctor. Seniors living a reclusive life or economically disadvantaged elderly will be particularly addressed. A motivation and communication concept supports the trial participants' compliance with trial procedures and practicing. Public and patient representatives are involved in the planning and conduction of the trial. Falls will be documented daily in a diary by the participants. These falls as well as injuries and complications will be ascertained during monthly phone visits. The falls efficacy scale, BBS, cognition (MoCA), Mood (GDS-15), quality of life (SF12), instrumental activities of daily living (IADL), use of medical and non-medical services (FIMA) and adherence will be assessed at months 3, 6, and 12 and inner correspondence with practices (ICPH) at month 6. The trial is funded by the Federal Ministry of Education and Research (BMBF 01GL1805). DISCUSSION: This study will determine whether EYT and Tai Chi reduce falls, injurious falls, fear of falling and healthcare utilisation and improve mobility, cognition, mood, quality of life and functional independence. A reduction of fall risk and fear of falling and an improvement of mobility, autonomy, quality of life, mood, and cognition are highly relevant for older people to cope with aging and diseases and to reduce healthcare costs. TRAIL REGISTRATION: www.drks.de. DRKS00016609. Registered 30th July 2019.


Assuntos
Acidentes por Quedas/prevenção & controle , Terapia por Exercício/métodos , Equilíbrio Postural/fisiologia , Qualidade de Vida/psicologia , Tai Chi Chuan/estatística & dados numéricos , Atividades Cotidianas , Idoso , Idoso de 80 Anos ou mais , Doença Crônica , Medo , Feminino , Humanos , Masculino , Resultado do Tratamento
17.
Eur Rev Med Pharmacol Sci ; 24(4): 1877-1886, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32141557

RESUMO

OBJECTIVE: Several plasma-derived exosome RNAs have been identified as key regulators in cancer development. They have been considered as potential biomarkers for a non-invasive "liquid biopsy" to diagnose and assess the progression of cancer. This study aimed to identify human lung adenocarcinoma-specific exosome RNAs in peripheral blood, while assessing the feasibility and efficiency of this recently developed deep-sequencing technology for transcriptome profiling. PATIENTS AND METHODS: Plasma-derived exosome RNAs were isolated from 13 lung adenocarcinoma patients, 3 patients with benign lung diseases, and 15 healthy volunteers. RNA-seq analysis of ribosomal RNA-depleted total RNA was performed. RNAs differentially expressed between lung adenocarcinoma and benign lung diseases or healthy volunteers were identified, followed by GO and KEGG pathway enrichment analyses for the identification of key exosome RNAs associated with lung adenocarcinomas. RESULTS: Significant differentially expressed RNAs, such as UDP glucuronosyltransferase family 1 member A1 (UGT1A1) and BAI1-associated protein 2 like 1 (BAIAP2L1), were identified as differentially expressed between lung adenocarcinoma patients and patients with benign lung diseases. Eight pseudogenes, including Tropomyosin 1 (Alpha) Pseudogene (LOC100129096), Prothymosin, Alpha Pseudogene 2 (PTMAP2), Cell Division Cycle 14C, Pseudogene (CDC14C), Tropomyosin 1 (Alpha) Pseudogene (LOC643634), Ferritin Heavy Chain 1 Pseudogene 2 (FTH1P2), Actin Related Protein 2/3 Complex Subunit 3 Pseudogene 3 (ARPC3P3), Ferritin Heavy Chain 1 Pseudogene 11 (FTH1P11), and Prothymosin Alpha Pseudogene 5 (PTMAP5) were identified from plasma-derived exosomes in lung adenocarcinoma patients, who were more abundant/detectable than healthy volunteers. CONCLUSIONS: Our data indicate that plasma-derived exosome RNAs, UGT1A1, and BAIAP2L1, as well as the eight isolated pseudogenes could serve as diagnostic and prognostic biomarkers for an effective non-invasive "liquid biopsy" of lung adenocarcinomas.


Assuntos
Adenocarcinoma de Pulmão/genética , Complexo Multienzimático de Ribonucleases do Exossomo/genética , Neoplasias Pulmonares/genética , Análise de Sequência de RNA , Adenocarcinoma de Pulmão/sangue , Adenocarcinoma de Pulmão/diagnóstico , Biologia Computacional , Complexo Multienzimático de Ribonucleases do Exossomo/sangue , Exossomos/metabolismo , Humanos , Neoplasias Pulmonares/sangue , Neoplasias Pulmonares/diagnóstico
18.
J Ethnopharmacol ; 254: 112683, 2020 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-32087321

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Acanthosicyos naudininus, Gomphocarpus fruticosus, and Cryptolepis decidua are, according to the knowledge of traditional healers, used in Namibia to treat inflammatory disorders such as pain, fever and skin rashes. AIM OF THE STUDY: The present study was conducted to evaluate the immunomodulatory effects and the possible underlying mechanisms of action of the plant extracts on peripheral blood mononuclear cells (PBMCs) such as T-lymphocytes. MATERIALS AND METHODS: Methanolic and EtOAc extracts of A. naudinianus, G. fruticosus and C. decidua were analysed for their immunomodulatory potential. PBMCs were isolated from the blood of healthy donors and incubated with the plant extracts at concentrations 100, 30, 10, 3, 1 and 0.3 µg/mL. Effects on proliferation and viability of activated human lymphocytes were assessed in comparison to ciclosporin A by flow cytometry using carboxyfluorescein succinimidyl ester (CFSE) and WST-1 assay. Flow cytometry by annexin V/propidium iodide (PI) staining was performed to investigate the necrotic/apoptotic effect of the plant extracts on mitogen-activated human lymphocytes. In addition, analysis of the influence of plant extracts on the regulatory mechanisms of T-lymphocytes was performed using activation marker and cytokine production assays. An HPLC-PDA-ELSD-ESIMS profile was recorded for each of the extracts. RESULTS: T-lymphocyte proliferation was inhibited in a dose-dependent manner by the extracts of A. naudinianus, G. fruticosus, and C. decidua in concentrations not causing apoptosis or necrosis. This effect was mediated by inhibition of lymphocyte activation, specifically the suppression of CD25 and CD69 surface receptor expression. Moreover, the extracts suppressed effector functions, as indicated by reduced production of IFN-γ and IL-2. Based on the HPLC profile, possible responsible compound classes could be identified for the extracts of A. naudinianus (cucurbitacins) and C. decidua (indole alkaloids), but not for G. fruticosus. CONCLUSIONS: The data show that the extracts of A. naudinianus, G. fruticosus and C. decidua have in vitro immunomodulatory activity and they interfere with the function of immunocompetent cells, suggesting an anti-inflammatory mode-of-action. The present chemical determination and pattern recognition results explain the therapeutic potency. However, further studies to investigate the therapeutic potential of the plants in inflammatory disorders should be done.


Assuntos
Anti-Inflamatórios/farmacologia , Apocynaceae/química , Cryptolepis/química , Imunomodulação/efeitos dos fármacos , Magnoliopsida/química , Extratos Vegetais/farmacologia , Anti-Inflamatórios/química , Apoptose/fisiologia , Proliferação de Células/fisiologia , Sobrevivência Celular/fisiologia , Células Cultivadas , Ciclosporina/farmacologia , Citocinas/metabolismo , Relação Dose-Resposta a Droga , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Namíbia , Extratos Vegetais/química , Linfócitos T/metabolismo , Linfócitos T/fisiologia
19.
Nat Photonics ; 14(11): 675-679, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34221109

RESUMO

Atomically strong light pulses can drive sub-optical-cycle dynamics. When the Rabi frequency - the rate of energy exchange between light and matter - exceeds the optical carrier frequency, fascinating non-perturbative strong-field phenomena emerge, such as high-harmonic generation and lightwave transport. Here, we explore a related novel subcycle regime of ultimately strong light-matter interaction without a coherent driving field. We use the vacuum fluctuations of nanoantennas to drive cyclotron resonances of two-dimensional electron gases to vacuum Rabi frequencies exceeding the carrier frequency. Femtosecond photoactivation of a switch element inside the cavity disrupts this 'deep-strong coupling' more than an order of magnitude faster than the oscillation cycle of light. The abrupt modification of the vacuum ground state causes spectrally broadband polarisation oscillations confirmed by our quantum model. In the future, this subcycle shaping of hybrid quantum states may trigger cavity-induced quantum chemistry, vacuum-modified transport, or cavity-controlled superconductivity, opening new scenarios for non-adiabatic quantum optics.

20.
Nat Commun ; 10(1): 3819, 2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31444341

RESUMO

Transit through the carbon liquid phase has significant consequences for the subsequent formation of solid nanocarbon detonation products. We report dynamic measurements of liquid carbon condensation and solidification into nano-onions over ∽200 ns by analysis of time-resolved, small-angle X-ray scattering data acquired during detonation of a hydrogen-free explosive, DNTF (3,4-bis(3-nitrofurazan-4-yl)furoxan). Further, thermochemical modeling predicts a direct liquid to solid graphite phase transition for DNTF products ~200 ns post-detonation. Solid detonation products were collected and characterized by high-resolution electron microscopy to confirm the abundance of carbon nano-onions with an average diameter of ∽10 nm, matching the dynamic measurements. We analyze other carbon-rich explosives by similar methods to systematically explore different regions of the carbon phase diagram traversed during detonation. Our results suggest a potential pathway to the efficient production of carbon nano-onions, while offering insight into the phase transformation kinetics of liquid carbon under extreme pressures and temperatures.

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