| 1. |
- Mansouri, Kamel, et al.
(författare)
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CoMPARA : Collaborative Modeling Project for Androgen Receptor Activity
- 2020
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 128:2, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Endocrine disrupting chemicals (EDCs) are xenobiotics that mimic the interaction of natural hormones and alter synthesis, transport, or metabolic pathways. The prospect of EDCs causing adverse health effects in humans and wildlife has led to the development of scientific and regulatory approaches for evaluating bioactivity. This need is being addressed using high-throughput screening (HTS) in vitro approaches and computational modeling.OBJECTIVES: In support of the Endocrine Disruptor Screening Program, the U.S. Environmental Protection Agency (EPA) led two worldwide consortiums to virtually screen chemicals for their potential estrogenic and androgenic activities. Here, we describe the Collaborative Modeling Project for Androgen Receptor Activity (CoMPARA) efforts, which follows the steps of the Collaborative Estrogen Receptor Activity Prediction Project (CERAPP).METHODS: The CoMPARA list of screened chemicals built on CERAPP's list of 32,464 chemicals to include additional chemicals of interest, as well as simulated ToxCast (TM) metabolites, totaling 55,450 chemical structures. Computational toxicology scientists from 25 international groups contributed 91 predictive models for binding, agonist, and antagonist activity predictions. Models were underpinned by a common training set of 1,746 chemicals compiled from a combined data set of 11 ToxCast (TM)/Tox21 HTS in vitro assays.RESULTS: The resulting models were evaluated using curated literature data extracted from different sources. To overcome the limitations of single-model approaches, CoMPARA predictions were combined into consensus models that provided averaged predictive accuracy of approximately 80% for the evaluation set.DISCUSSION: The strengths and limitations of the consensus predictions were discussed with example chemicals; then, the models were implemented into the free and open-source OPERA application to enable screening of new chemicals with a defined applicability domain and accuracy assessment. This implementation was used to screen the entire EPA DSSTox database of similar to 875,000 chemicals, and their predicted AR activities have been made available on the EPA CompTox Chemicals dashboard and National Toxicology Program's Integrated Chemical Environment.
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| 2. |
- Sun, Li, et al.
(författare)
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Influence of Cr layer thickness on the static and dynamic performances of Tb/Cr/Ni80Fe20 structure
- 2017
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 695, s. 1324-1328
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Tidskriftsartikel (refereegranskat)abstract
- Using the vibrating sample magnetometer and ex situ vector network analyzer ferromagnetic resonance, the static and dynamic magnetic properties of Tb (4 nm)/Cr (t(Cr))/Ni80Fe20 (12 nm) trilayers with different thickness of Cr layer (from 0.2 to 4.0 nm) were investigated comparing with those of Ni80Fe20 film. From the results of in-plane static magnetic hysteresis loops, we analyzed the soft magnetic properties and in-plane anisotropy, along with obtaining the saturation magnetization (M-s) which shows no obvious reducing and a modulation akin to RKKY coupling. By fitting the relationship of resonance field and linewidth versus resonance frequency, the effective magnetization 4 pi M-eff, gyromagnetic ratio gamma, and effective damping coefficient (alpha(eff)) were extracted. It is worthwhile to mention that the inserting of ultrathin Cr layer (0.2 nm) enhanced the above parameters obviously, which then backed down towards their values in Ni80Fe20 film with increasing the thickness of Cr layer as a result of the weakening magnetic proximity effect and the decreasing spin-pumping effect in trilayers. Finally, they became flattening with the Cr layer thicker than 1 nm where oscillations are also observed in the value of g and aeff. Interestingly, the oscillations in aeff and g are consistent with each other, which implies the damping mechanism mainly related to the spin-orbit coupling originating from the indirect interaction between Tb and Ni80Fe20. In addition, the inhomogeneous broadening (Delta H-0) were determined to be very small which further ascertain the accurate of the aeff.
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| 3. |
- Gu, Jian, et al.
(författare)
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Visualizing Material Processing via Photoexcitation-Controlled Organic-Phase Aggregation-Induced Emission
- 2021
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Ingår i: RESEARCH. - : American Association for the Advancement of Science (AAAS). - 2639-5274. ; 2021
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation-induced emission (AIE) has been much employed for visualizing material aggregation and self-assembly. However, water is generally required for the preparation of the AIE aggregates, the operation of which limits numerous material processing behaviors. Employing hexathiobenzene-based small molecules, monopolymers, and block copolymers as different material prototypes, we herein achieve AIE in pure organic phases by applying a nonequilibrium strategy, photoexcitation-controlled aggregation. This strategy enabled a dynamic change of molecular conformation rather than chemical structure upon irradiation, leading to a continuous aggregation-dependent luminescent enhancement (up to similar to 200-fold increase of the luminescent quantum yield) in organic solvents. Accompanied by the materialization of the nonequilibrium strategy, photoconvertible self-assemblies with a steady-state characteristic can be achieved upon organic solvent processing. The visual monitoring with the luminescence change covered the whole solution-to-film transition, as well as the in situ photoprocessing of the solid-state materials.
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| 4. |
- Karalija, Amar, 1984-
(författare)
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Diagnostic and therapeutic strategies following spinal cord and brachial plexus injuries
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traumatic injuries to the spinal cord and brachial plexus induce a significant inflammatory response in the nervous tissue with progressive degeneration of neurons and glial cells, and cause considerable physical and mental suffering in affected patients. This thesis investigates the effects of the antioxidants N-acetyl-cysteine (NAC) and acetyl-L- carnitine (ALC) on the survival of motoneurons in the brainstem and spinal cord, the expression of pro-apoptotic and pro-inflammatory cell markers, axonal sprouting and glial cell reactions after spinal hemisection in adult rats. In addition, a novel MRI protocol has been developed to analyse the extent of neuronal degeneration in the spinal cord. Rubrospinal neurons and tibial motoneurons were pre-labelled with the fluorescent tracer Fast Blue one week before cervical C3 or lumbar L5 spinal cord hemisection. The intrathecal treatment with the antioxidants NAC (2.4mg/day) or ALC (0.9 mg/day) was initiated immediately after injury using Alzet2002 osmotic mini pumps. Spinal cord injury increased the expression of apoptotic cell markers BAX and caspase 3, induced significant degeneration of rubrospinal neurons and spinal motoneurons with associated decrease in immunoreactivity for microtubule-associated protein-2 (MAP2) in dendritic branches, synaptophysin in presynaptic boutons and neurofilaments in nerve fibers. Immunostaining for the astroglial marker glial fibrillary acidic protein and microglial markers OX42 and ED1 was markedly increased. Treatment with NAC and ALC attenuated levels of BAX, caspase 3, OX42 and ED1 expression after 2 weeks postoperatively. After 4-8 weeks of continuous intratheca ltreatment, NAC and ALC rescued approximately half of the rubrospinal neurons and spinal motoneurons destined to die, promoted axonal sprouting, restored the density of MAP2 and synaptophysin immunoreactivity and reduced the microglial reaction. However, antioxidant therapy did not affect the reactive astrocytes in the trauma zone. The inflammation modulating properties of ALC were also studied using cultures of human microglial cells. ALC increased the microglial production of interleukin IL-6 and BDNF, thereby possibly mediating the anti-inflammatory and pro-regenerative effects shown in vivo. To study degeneration in the spinal cord following pre-ganglionic and post-ganglionic brachial plexus injuries, adult rat models of ventral root avulsion and peripheral nerve injury were used. A novel MRI protocol was employed and the images were compared to morphological changes found in histological preparations. Ventral root avulsion caused degeneration of dendritic branches and axonal terminals in the spinal cord, followed by significant shrinkage of the ventral horn. Extensive astroglial and microglial reactions were detected in the histological preparations. Peripheral nerve injury reduced the density of dendritic branches but did not cause shrinkage of the ventral horn. Quantitative analysis of MRI images demonstrated changes in the ventral horn following ventral root avulsion only, thus validating the developed MRI technique as a possible tool for the differentiation of pre-ganglionic and post-ganglionic nerve injuries.
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| 5. |
- Li, Zhongyu, et al.
(författare)
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Lighting up solid states using a rubber
- 2021
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- It is crucial and desirable to develop green and high-efficient strategies to regulate solid-state structures and their related material properties. However, relative to solution, it is more difficult to break and generate chemical bonds in solid states. In this work, a rubbing-induced photoluminescence on the solid states of ortho-pyridinil phenol family was achieved. This rubbing response relied on an accurately designed topochemical tautomerism, where a negative charge, exactly provided by the triboelectric effect of a rubber, can induce a proton transfer in a double H-bonded dimeric structure. This process instantaneously led to a bright-form tautomer that can be stabilized in the solid-state settings, leading to an up to over 450-fold increase of the fluorescent quantum yield of the materials. The property can be repeatedly used due to the reversibility of the tautomerism, enabling encrypted applications. Moreover, a further modification to the structure can be accomplished to achieve different properties, opening up more possibilities for the design of new-generation smart materials. Changes in molecular properties due to stimuli response are critically important for the development of new materials. However, most processes are slow or inefficient in the solid state. Here the authors demonstrate property switching in the solid state using a rubbing-induced tautomerism in multiple hydrogen-bonded donor-acceptor couples.
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| 6. |
- Shen, Shen, et al.
(författare)
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Making multi-twisted luminophores produce persistent room-temperature phosphorescence
- 2023
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Ingår i: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6520 .- 2041-6539. ; 14:4, s. 970-978
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Tidskriftsartikel (refereegranskat)abstract
- Multi-twisted molecules, especially those with more than four branched rotation axes, have served as superior prototypes in diverse fields like molecular machines, optical materials, sensors, and so forth. However, due to excessive non-radiative relaxation of these molecules, it remains challenging to address their persistent room-temperature phosphorescence (pRTP), which limits their further development. Herein, we develop a host-guest energy-transfer relay strategy to improve the phosphorescence lifetime of multi-twisted luminophores by over thousand-fold to realize pRTP, which can be witnessed by the naked eye after removing the excitation light source. Moreover, we employ photoexcitation-induced molecular rearrangement to further prolong the phosphorescence lifetime, which, to the best of our knowledge, is the first example of photoactivation in ordered host-guest systems. Our systems show superior humidity and oxygen resistance, enabling long-term (at least over 9-12 months) stability of the pRTP properties. By achieving pRTP of multi-twisted luminophores, this work can advance the understanding of molecular photophysical mechanisms and guide the study of more molecular systems that are difficult to achieve pRTP.
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| 7. |
- Sun, Hao, et al.
(författare)
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Engineering Tunable Ratiometric Dual Emission in Single Emitter-based Amorphous Systems
- 2024
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773.
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Tidskriftsartikel (refereegranskat)abstract
- Molecular emitters with multi-emissive properties are in high demand in numerous fields, while these properties basically depend on specific molecular conformation and packing. For amorphous systems, special molecular arrangement is unnecessary, but it remains challenging to achieve such luminescent behaviors. Herein, we present a general strategy that takes advantage of molecular rigidity and S1-T1 energy gap balance for emitter design, which enables fluorescence-phosphorescence dual-emission properties in various solid forms, whether crystalline or amorphous. Subsequently, the amorphism of the emitters based polymethyl methacrylate films endowed an in situ regulation of the dual-emissive characteristics. With the ratiometric regulation of phosphorescence by external stimuli and stable fluorescence as internal reference, highly controllable luminescent color tuning (yellow to blue including white emission) was achieved. There properties together with a persistent luminous behavior is of benefit for an irreplaceable set of optical information combination, featuring an ultrahigh-security anti-counterfeiting ability. Our research introduces a concept of eliminating the crystal-form and molecular-conformational dependence of complex luminescent properties through emitter molecular design. This has profound implications for the development of functional materials. A molecular structural strategy enabling single emitter based dual-emission properties in various solid forms is presented. The developed amorphous films endow in situ regulation of the dual-emissive characteristics to show highly controllable multiple luminescent color tuning (yellow to blue including white emission), which benefits to the construction of an irreplaceable set of optical information combination.image
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| 8. |
- Sun, Li, et al.
(författare)
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Anomalously large ferromagnetic resonance linewidth in the Gd/Cr/Fe film plane
- 2018
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 451, s. 480-486
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Tidskriftsartikel (refereegranskat)abstract
- As an important parameter for characterizing the magnetization dynamics, Gilbert damping constant a in a thin film or a multilayer is generally extracted from the linear fitting of the frequency-dependence of the ferromagnetic resonance linewidth, sometimes accompanied with a tiny deviation of the linewidth to a smaller value at the low-frequency or high-frequency region due to the two-magnon scattering with an in-plane-field configuration, in which an in-plane magnetic field H perpendicular to a microwave field h was applied in film plane during measurement. In contrast, here we report, in ultrathin Gd/Cr/Fe multilayers, an anomalously large linewidth in the film plane at the low-frequency region. For the first time, we have successfully extracted the Gilbert damping constant from perfect theoretical fitting to the experimental data, by considering the effective direction of the magnetization around in precession staying out of the film plane when the in-pane H at which the precession starts is below the saturation field. This magnetization deviation from the film plane is found to have an obvious contribution to the enhanced linewidth caused by two magnon scattering, while slightly reduce the intrinsic linewidth. Under the same resonance frequency, the deviation angle reaches the maximum values at t(Cr) = 1.0 nm while decreases when t(Cr) increases to 1.5 nm, which coincides with the trend of the surface perpendicular anisotropy constant K-perpendicular to. A reduced intrinsic damping constant alpha is obtained as the introduction of Gd layer and Cr layer as a result of the competition between the spin pumping effect and the interfacial effects at the Fe/Gd and Fe/Cr interfaces. While the decreasing alpha for film with Cr layer thickness increasing to 1.5 nm might means the contribution of the electron density of states at the Fermi energy n(E-F). This study offers an effective way to accurately obtain the intrinsic damping constant of spintronic materials/devices, which is essential for broad applications in spintronics.
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| 9. |
- Xing, Yi, et al.
(författare)
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Water molecular bridge-induced selective dual polarization in crystals for stable multi-emitters
- 2022
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Ingår i: Chemical Science. - : Royal Society of Chemistry. - 2041-6520 .- 2041-6539. ; 13:20, s. 6067-6073
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Tidskriftsartikel (refereegranskat)abstract
- In the solid state, the molecular polarization of donor-acceptor (D-A) molecules can be implemented in a simple way via the use of an external polarizing source (e.g., an electric field). However, internal chemical polarization approaches are less studied due to difficulties related to controlling the charge-separation orientation in the solid state. Herein, a series of D-A molecules with both a proton donor and an acceptor were designed. Water-based molecular bridges were then established in their crystal structures, which firmly and alternately connected the proton donor of one molecule and the acceptor of another via an intermolecular H-bond network. In this way, the selective dual polarization of a phenolic hydroxyl group and a pyridinyl group could be achieved, owing to the strengthening of the charge-separation orientation upon the simultaneous deprotonation and protonation of the D-A molecules. This effect led to a 3-5-fold amplification of the molecular dipole moment in the crystal form relative to the monomeric state. On this basis, multi-excitation and multi-emission characteristics were achieved in these charge-separated crystals, endowing them with the ability to visually detect the energy of a light source, covering a wide range of the UV-Vis spectral region. This work provides a practical chemical approach for developing intrinsically polarized systems that can exhibit stable but distinct molecular photophysical properties.
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| 10. |
- Zhang, Man, et al.
(författare)
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Highly Efficient Room-Temperature Light-Induced Synthesis of Polymer Dots: A Programming Control Paradigm of Polymer Nanostructurization from Single-Component Precursor
- 2023
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 145:45, s. 24657-24668
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Tidskriftsartikel (refereegranskat)abstract
- Polymer dots (PDs) have raised considerable research interest due to their advantages of designable nanostructures, high biocompatibility, versatile photoluminescent properties, and recyclability as nanophase. However, there remains a lack of in situ, real-time, and noncontact methods for synthesizing PDs. Here we report a rational strategy to synthesize PDs through a well-designed single-component precursor (an asymmetrical donor-acceptor-donor molecular structure) by photoirradiation at ambient temperature. In contrast to thermal processes that normally lack atomic economy, our method is mild and successive, based on an aggregation-promoted sulfonimidization triggered by photoinduced delocalized intrinsic radical cations for polymerization, followed by photooxidation for termination with structural shaping to form PDs. This synthetic approach excludes any external additives, rendering a conversion rate of the precursor exceeding 99%. The prepared PDs, as a single entity, can realize the integration of nanocore luminescence and precursor-transferred luminescence, showing 41.5% of the total absolute luminescence quantum efficiency, which is higher than most reported PD cases. Based on these photoluminescent properties, together with the superior biocompatibility, a unique membrane microenvironmental biodetection could be exemplified. This strategy with programming control of the single precursor can serve as a significant step toward polymer nanomanufacturing with remote control, high-efficiency, precision, and real-time operability.
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