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1.
Psychiatry Res ; 339: 116037, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38959578

RESUMO

Psychotic disorders have been linked to immune-system abnormalities, increased inflammatory markers, and subtle neuroinflammation. Studies further suggest a dysfunctional blood brain barrier (BBB). The endothelial Glycocalyx (GLX) functions as a protective layer in the BBB, and GLX shedding leads to BBB dysfunction. This study aimed to investigate whether a panel of 11 GLX molecules derived from peripheral blood could differentiate antipsychotic-naïve first-episode psychosis patients (n47) from healthy controls (HC, n49) and whether GLX shedding correlated with symptom severity. Blood samples were collected at baseline and serum was isolated for GLX marker detection. Machine learning models were applied to test whether patterns in GLX markers could classify patient groups. Associations between GLX markers and symptom severity were explored. Patients showed significantly increased levels of three GLX markers compared to HC. Based on the panel of 11 GLX markers, machine learning models achieved a significant mean classification accuracy of 81%. Post hoc analysis revealed associations between increased GLX markers and symptom severity. This study demonstrates the potential of GLX molecules as immuno-neuropsychiatric biomarkers for early diagnosis of psychosis, as well as indicate a compromised BBB. Further research is warranted to explore the role of GLX in the early detection of psychotic disorders.

2.
BMJ Case Rep ; 17(4)2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38627047

RESUMO

We present a case of a man in his 30s presenting with ST-segment elevation myocardial infarction and eosinophilia. The patient underwent thrombus aspiration and initially echocardiographic evaluation was normal. The patient was discharged after 2 days, but was hospitalised again after 6 days. Echocardiographic evaluation now revealed a thrombus formation on the aortic valve. Laboratory data revealed increasing eosinophilia, and treatment with high-dosage corticosteroids and hydroxyurea was initiated as eosinophilic disease with organ manifestations could not be precluded. Eosinophils normalised and the patient was discharged again. The combination of hypereosinophilia and absence of infection, rheumatological disorders and malignancy, led to reactive or idiopathic hypereosinophilic syndrome being the most plausible diagnoses. The patient was closely monitored in the cardiology and haematology outpatient clinics. Echocardiographic evaluation, performed 6 weeks after the patient was discharged, showed significant regression in the size of the thrombus mass.


Assuntos
Síndrome Hipereosinofílica , Infarto do Miocárdio com Supradesnível do Segmento ST , Trombose , Masculino , Humanos , Infarto do Miocárdio com Supradesnível do Segmento ST/etiologia , Valva Aórtica/diagnóstico por imagem , Síndrome Hipereosinofílica/complicações , Síndrome Hipereosinofílica/diagnóstico , Síndrome Hipereosinofílica/tratamento farmacológico , Hidroxiureia , Trombose/diagnóstico por imagem , Trombose/tratamento farmacológico , Trombose/etiologia
3.
Dalton Trans ; 53(17): 7619-7627, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38618973

RESUMO

Metal hydroborates and their derivatives have been receiving attention as potential solid-state ion conductors for battery applications owing to their impressive electrochemical and mechanical characteristics. However, to date only a fraction of these compounds has been investigated as solid-state electrolytes. Here, MB12H11NH3 (M = Li and Na) hydroborates are synthesized and investigated as electrolyte materials for all-solid-state batteries. The room temperature α-NaB12H11NH3 was structurally solved in P212121 (a = 7.1972(3) Å, b = 9.9225(4) Å, and c = 14.5556(5) Å). It shows a polymorphic structural transition near 140 °C to cubic Fm3̄m. LiB12H11NH3 and NaB12H11NH3 exhibit cationic conductivities of σ(Li+) = 3.0 × 10-4 S cm-1 and σ(Na+) = 1.2 × 10-4 S cm-1 at 200 °C. Hydration is found to improve ionic conductivity of the hydroborates. It is presumed that modest ionic conductivities could be due to a lack of significant re-orientational dynamics in the crystal structure resulting from the presence of the bulky -NH3 group in the anion.

4.
Talanta ; 272: 125810, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38387374

RESUMO

Matrix effects can affect detection limits, precision, and accuracy and lead to signal enhancement or suppression effects in gas chromatography analysis. Analyte protectants, such as shikimic acid and gluconolactone, can imitate the effect of matrix components and reduce the differences in matrix effect between samples. This study aimed to investigate the ability of analyte protectants to enhance gas chromatography detector signals of different oxygenated-polycyclic aromatic hydrocarbons. Addition of 100 µg L-1 shikimic acid and 200 µg L-1 gluconolactone effectively enhanced detector response of the investigated target compounds. Addition of a higher content of analyte protectants did not result in any further enhancement. It was found that between four and eleven consecutive injections of a standard solution with analyte protectants were required to obtain a stable compound response. The long-term signal stability was then maintained with subsequent injections, though an overall negative drift of the system was observed over the sequence of 200 investigated injections. Analysis of the actual sample matrix instead of standards in pure solvent, as presented in this study, could also be a way to minimize the required number of injections. Shikimic acid and gluconolactone were first and foremost able to enhance signals of oxygenated-polycyclic aromatic hydrocarbons with similar functional groups (hydroxyl) in their molecular structure. It can be relevant to consider alternative analyte protectants with different functional groups according to the type of target compounds investigated.

5.
Environ Sci Pollut Res Int ; 30(57): 121107-121123, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37950122

RESUMO

This study aimed to investigate the spatial distribution of micropollutants in wastewater related to catchment area, and their environmental risks and fate. About 24-h flow proportional effluent (n = 26) wastewater samples were collected from eight WWTPs across Denmark. From five of these WWTPs corresponding influent samples (n = 20) were collected. Samples were enriched by multi-layer solid phase and analysed by liquid chromatography-high-resolution mass spectrometry and comprehensive two-dimensional gas chromatography with high-resolution mass spectrometry detection. We detected and quantified 79 micropollutants from a list of 291 micropollutants in at least one influent or effluent wastewater sample. From this we found that 54 micropollutants decreased in concentrations during wastewater treatment, while O-desmethylvenlafaxine, carbamazepine, amitriptyline, benzothiazole, terbutryn, and citalopram increased in concentrations through the WWTP.The toxicity of effluent wastewater samples was assessed by EC50 using Raphidocelis subcapitata (R. subcapitata) and LC50 using the crustacean Daphnia magna (D. Magna), for which six micropollutants were detected above the predicted no-effect concentration. Our study demonstrates that catchment area influences the micropollutant composition of wastewater. Out of 19 pharmaceuticals, the measured concentration in influent wastewater was predicted within a factor of 10 from sale numbers and human excretion, which demonstrates the strong influence of catchment area on micropollutant composition.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Humanos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Dinamarca
6.
Environ Sci Technol ; 57(25): 9287-9297, 2023 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-37307429

RESUMO

Broad screening approaches for monitoring wastewater are normally based on reversed-phase liquid chromatography (LC) coupled to high-resolution mass spectrometry (HRMS). This method is not sufficient for the very polar micropollutants, neglected in the past due to a lack of suitable analytical methods. In this study, we used supercritical fluid chromatography (SFC) to detect very polar and yet-undetected micropollutants in wastewater effluents. We tentatively identified 85 compounds, whereas 18 have only rarely been detected and 11 have not previously been detected in wastewater effluents such as 17α-hydroxypregnenolone, a likely transformation product (TP) of steroids, and 1H-indole-3-carboxamide, a likely TP from new synthetic cannabinoids. Suspect screening of 25 effluent wastewater samples from 8 wastewater treatment plants revealed several distinct potential pollution sources such as a pharmaceutical company and a golf court. The analysis of the same samples with LC-HRMS showed clearly how SFC increases the ionization efficiency for low-molecular-weight micropollutants (m/z < 300 Da) by a factor 2 to 87 times, which significantly improved the mass spectra for identifying very polar compounds. In order to assess which micropollutants might be of environmental concern, literature and toxicological databases were screened. There was a lack of available hazard and bio-activity data for regulatory-relevant in vitro and in vivo assays for >50% of the micropollutants. Especially, 70% of the data were lacking for the whole organism (in vivo) tests.


Assuntos
Cromatografia com Fluido Supercrítico , Poluentes Químicos da Água , Águas Residuárias , Poluentes Químicos da Água/análise , Espectrometria de Massas/métodos , Compostos Orgânicos
7.
J Chromatogr A ; 1676: 463280, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35785676

RESUMO

This study aimed to investigate the ability of analyte protectants to enhance GC-MS signals and compensate matrix effects for a range of micropollutants in pure standard, effluent, and influent wastewater samples during analysis and detection. Wastewater samples were prepared for analysis using multilayer solid phase extraction for the purpose of extracting sample components with a broad range of physical-chemical properties. The sample extracts were either spiked or not spiked with target compounds and four analyte protectants: 3-ethoxy-1,2-propanediol, D-sorbitol, gluconolactone, and shikimic acid. In this way, it was possible to evaluate the matrix effects of wastewater samples and compare the use of analyte protectants with the conventional correction method of allocating a best matching internal standard to each target compound. A relation was observed between level of wastewater treatment and matrix effects, with the largest effects observed for influent samples and the smallest effects for effluent samples. Compensation of matrix effects with analyte protectants gave comparable results with the conventional correction method of allocating a best matching internal standard to each of the 13 investigated micropollutants. The best overall compensation was observed using analyte protectants and the internal standard correction method in combination.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extração em Fase Sólida , Sorbitol/química
8.
Acta Ophthalmol ; 100(8): e1624-e1629, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35673897

RESUMO

PURPOSE: To evaluate treatment efficacy in diabetic macular oedema (DME) comparing a study population receiving combined intravitreal vascular endothelial growth factor (VEGF) inhibition and focal/grid photocoagulation with a matched, real-world population receiving standard of care treatment. METHODS: In an exploratory study, we included 43 eyes from 32 patients from a previously published study as well as 46 eyes from 38 standard-of-care patients. The study population had received a loading dose of three monthly aflibercept injections followed by focal/grid photocoagulation and additional aflibercept pro re nata. Principal measurements at 12 months were numbers of intravitreal injections, best corrected visual acuity (BCVA) and central retinal thickness (CRT). RESULTS: At baseline, there were no differences between groups regarding age, sex, body mass index, haemoglobin A1 C, systolic pressure or type of diabetes, but the study population had a higher diastolic pressure (81.6 versus 72.1 mmHg, p = 0.03) and a lower duration of diabetes (12.3 versus 23.2 years, p = 0.03). At month 12, patients in the study group had a higher visual acuity (79.6 versus 74.3 ETDRS letters, p = 0.03), despite having received fewer aflibercept injections (4.4 versus 5.9, p < 0.01) with a higher likelihood of having only received the three mandatory injections in the loading phase (39.5% versus 13.0%, p = 0.01). CONCLUSION: In comparison to a matched, real-world DME-population, patients in combined treatment with intravitreal aflibercept and postloading focal/grid photocoagulation obtained a better functional outcome despite having received fewer intravitreal injections. Future randomized studies are needed to evaluate the long-term efficacy of this combined treatment regimen.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Edema Macular , Humanos , Adulto Jovem , Adulto , Edema Macular/diagnóstico , Edema Macular/tratamento farmacológico , Edema Macular/etiologia , Ranibizumab/uso terapêutico , Fator A de Crescimento do Endotélio Vascular , Inibidores da Angiogênese , Receptores de Fatores de Crescimento do Endotélio Vascular , Retinopatia Diabética/complicações , Retinopatia Diabética/diagnóstico , Retinopatia Diabética/tratamento farmacológico , Proteínas Recombinantes de Fusão/uso terapêutico , Injeções Intravítreas , Fotocoagulação a Laser/métodos , Diabetes Mellitus/tratamento farmacológico
9.
Water Res ; 219: 118599, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35598471

RESUMO

In this study, micropollutants in wastewater effluents were prioritized by monitoring the composition of influent and effluent wastewater by liquid chromatography - high-resolution mass spectrometry (LCHRMS) non-target screening (NTS) analysis. The study shows how important data pre-processing and filtering of raw data is to produce reliable NTS data for comparison of compounds between many samples (37 wastewater samples) analyzed at different times. Triplicate injections were critical for reducing the number of false-positive detections. Intensity drift corrections within and between batches analyzed months apart made peak intensities comparable across samples. Adjustment of the feature detection threshold was shown to be important, due to large intensity variations for low abundance compounds across batches. When the threshold correction cut-offs, or the filtering of relevant compounds by the occurrence frequency, were too stringent, a high number of false positive transformation products (TPs) were reported. We also showed that matrix effect correction by internal standards can over- or under-correct the intensity for unknown compounds, thus the TIC matrix effect correction was shown as an additional tool for a retention time dependent matrix effect correction. After these preprocessing and filtering steps, we identified 78 prioritized compounds, of which 36 were persistent compounds, defined as compounds with a reduction in peak intensity between influent and effluent wastewater <50%, and 13 compounds were defined as TPs because they occurred solely in the effluent samples. Some examples of persistent compounds are 1,3-diphenylguanidine, amisulpride and the human metabolites from losartan, verapamil and methadone. To our knowledge, nine of the identified TPs have not been previously described in effluent wastewater. The TPs were derived from metoprolol, fexofenadine, DEET and losartan. The screening of all identified compounds in effluent samples from eight wastewater treatment plants (WWTPs) showed that potential drugs of abuse, anti-psychotic and anti-depressant drugs were predominant in the capital city region, whereas the anti-epileptic agents and agricultural pesticides were dominant in more rural areas.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Monitoramento Ambiental , Humanos , Losartan/análise , Águas Residuárias/análise , Poluentes Químicos da Água/análise
10.
Phys Rev Lett ; 128(13): 130502, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35426703

RESUMO

We investigate the limits of thermometry using quantum probes at thermal equilibrium within the Bayesian approach. We consider the possibility of engineering interactions between the probes in order to enhance their sensitivity, as well as feedback during the measurement process, i.e., adaptive protocols. On the one hand, we obtain an ultimate bound on thermometry precision in the Bayesian setting, valid for arbitrary interactions and measurement schemes, which lower bounds the error with a quadratic (Heisenberg-like) scaling with the number of probes. We develop a simple adaptive strategy that can saturate this limit. On the other hand, we derive a no-go theorem for nonadaptive protocols that does not allow for better than linear (shot-noise-like) scaling even if one has unlimited control over the probes, namely, access to arbitrary many-body interactions.


Assuntos
Termometria , Teorema de Bayes , Termometria/métodos
11.
Int J Mol Sci ; 23(6)2022 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-35328755

RESUMO

Ischemic conditioning and exercise have been suggested for protecting against brain ischemia-reperfusion injury. However, the endogenous protective mechanisms stimulated by these interventions remain unclear. Here, in a comprehensive translational study, we investigated the protective role of extracellular vesicles (EVs) released after remote ischemic conditioning (RIC), blood flow restricted resistance exercise (BFRRE), or high-load resistance exercise (HLRE). Blood samples were collected from human participants before and at serial time points after intervention. RIC and BFRRE plasma EVs released early after stimulation improved viability of endothelial cells subjected to oxygen-glucose deprivation. Furthermore, post-RIC EVs accumulated in the ischemic area of a stroke mouse model, and a mean decrease in infarct volume was observed for post-RIC EVs, although not reaching statistical significance. Thus, circulating EVs induced by RIC and BFRRE can mediate protection, but the in vivo and translational effects of conditioned EVs require further experimental verification.


Assuntos
Vesículas Extracelulares , Traumatismo por Reperfusão , Animais , Modelos Animais de Doenças , Células Endoteliais , Humanos , Isquemia , Camundongos
12.
Inorg Chem ; 60(15): 10943-10957, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34251804

RESUMO

Metal closo-borates and their derivatives have shown promise in several fields of application from cancer therapy to solid-state electrolytes partly owing to their stability in aqueous solutions and high thermal stability. We report the synthesis and structural analysis of α- and ß-CaB10H10, which are structurally and energetically similar, both showing a tetrahedral coordination of Ca2+ to four closo-borate cages. The main distinctions between the α- and ß-polymorph are found in the crystal system (monoclinic or orthorhombic), topology (wurtzite or cag), and the degree of displacement of Ca2+ from the center of the coordination tetrahedron. Neutron vibrational spectroscopy measurements further revealed distinct perturbations in the cation-anion interactions arising from the different crystal structures. We also synthesized and structurally investigated five stoichiometric hydrates, CaB10H10·xH2O, x = 1, 4, 5, 6, and 7, and discovered an order-disorder polymorphic transition, α- to ß-CaB10H10·6H2O. The hydrates reveal a rich structural diversity with ordered structures, CaB10H10·xH2O, x = 1, 4, 5, 6, and 7, as well as disordered structures, x = 6 and 8. The latter allow for a continuum of compositions within 7-8 molecules of crystal water. The DFT-optimized experimental crystal structures reveal complex networks of three types of hydrogen interactions: dihydrogen bonds, B-Hδ-···+δH-O; hydrogen-hydrogen interactions, B-H···H-B; and hydrogen bonds, O-Hδ+···-δO-H. A rather short B-H···H-B (2.14 Å) interaction is observed for CaB10H10·5H2O, which is locally stabilized by four hydrogen bonds.

13.
ACS Appl Mater Interfaces ; 13(19): 22142-22149, 2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-33960773

RESUMO

Constructing artificial lymph vessels, which play a key role in the immune response, can provide new insights into immunology and disease pathologies. An immune tissue is a highly complex network that consists of lymph vessels, with a "beads-on-a-string" knotted structure. Herein, we present the facile and rapid fabrication of beads-on-a-string knotted cell-laden fibers using coaxial spinning of alginate by exploiting the Plateau-Rayleigh instability. It is shown how alterations in the flow rate and alginate concentration greatly affect the beads-on-a-string structure, rooted in the Plateau-Rayleigh instability theory. Biocompatibility was confirmed by the lactate dehydrogenase (LDH) assay and live/dead staining of the encapsulated human white blood cells. Finally, the encapsulated white blood cells were still functional as indicated by their anti-CD3 activation to secrete interleukin 2. The rapid fabrication of a cell-laden beads-on-a-string three-dimensional (3D) culture platform enables a crude mimicry of the lymph vessel structure. With joint expertise in immunology, microfluidics, and bioreactors, the technology may contribute to the mechanistic assay of human immune response in vitro and functional replacement.


Assuntos
Alginatos/química , Vasos Linfáticos/química , Alicerces Teciduais/química , Animais , Humanos , Camundongos
14.
ACS Nano ; 14(8): 10294-10304, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32658451

RESUMO

The lower limit of metal hydride nanoconfinement is demonstrated through the coordination of a molecular hydride species to binding sites inside the pores of a metal-organic framework (MOF). Magnesium borohydride, which has a high hydrogen capacity, is incorporated into the pores of UiO-67bpy (Zr6O4(OH)4(bpydc)6 with bpydc2- = 2,2'-bipyridine-5,5'-dicarboxylate) by solvent impregnation. The MOF retained its long-range order, and transmission electron microscopy and elemental mapping confirmed the retention of the crystal morphology and revealed a homogeneous distribution of the hydride within the MOF host. Notably, the B-, N-, and Mg-edge XAS data confirm the coordination of Mg(II) to the N atoms of the chelating bipyridine groups. In situ 11B MAS NMR studies helped elucidate the reaction mechanism and revealed that complete hydrogen release from Mg(BH4)2 occurs as low as 200 °C. Sieverts and thermogravimetric measurements indicate an increase in the rate of hydrogen release, with the onset of hydrogen desorption as low as 120 °C, which is approximately 150 °C lower than that of the bulk material. Furthermore, density functional theory calculations support the improved dehydrogenation properties and confirm the drastically lower activation energy for B-H bond dissociation.

15.
Inorg Chem ; 59(11): 7768-7778, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32395988

RESUMO

Ammine metal borohydrides show potential for solid-state hydrogen storage and can be tailored toward hydrogen release at low temperatures. Here, we report the synthesis and structural characterization of seven new ammine metal borohydrides, M(BH4)3·nNH3, M = La (n = 6, 4, or 3) or Ce (n = 6, 5, 4, or 3). The two compounds with n = 6 are isostructural and have new orthorhombic structure types (space group P21212) built from cationic complexes, [M(NH3)6(BH4)2]+, and are charge balanced by BH4-. The structure of Ce(BH4)3·5NH3 is orthorhombic (space group C2221) and is built from cationic complexes, [Ce(NH3)5(BH4)2]+, and charge balanced by BH4-. These are rare examples of borohydride complexes acting both as a ligand and as a counterion in the same compound. The structures of M(BH4)3·4NH3 are monoclinic (space group C2), built from neutral molecular complexes of [M(NH3)4(BH4)3]. The new compositions, M(BH4)3·3NH3 (M = La, Ce), among ammine metal borohydrides, are orthorhombic (space group Pna21), containing molecular complexes of [M(NH3)3(BH4)3]. A revised structural model for A(BH4)3·5NH3 (A = Y, Gd, Dy) is presented, and the previously reported composition A(BH4)3·4NH3 (A = Y, La, Gd, Dy) is proposed in fact to be M(BH4)3·3NH3 along with a new structural model. The temperature-dependent structural properties and decomposition are investigated by in situ synchrotron radiation powder X-ray diffraction in vacuum and argon atmosphere and by thermal analysis combined with mass spectrometry. The compounds with n = 6, 5, and 4 mainly release ammonia at low temperatures, while hydrogen evolution occurs for M(BH4)3·3NH3 (M = La, Ce). Gas-release temperatures and gas composition from these compounds depend on the physical conditions and on the relative stability of M(BH4)3·nNH3 and M(BH4)3.

16.
Biomaterials ; 253: 120108, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32428776

RESUMO

Great research efforts have been invested in developing nerve guidance conduits (NGCs), which can direct axons advance and guide peripheral neural regeneration. Here, three different aspects of NGC design, namely anisotropy, photocatalytic stimulation and self-assembly at implantation site, were unitedly addressed. Firstly, melt electrowriting (MEW) was used to print anisotropic, microfibrous PCL architectures. Specifically, by tailoring the fiber spacing ratio between two arms of the grid patterns (1-1, 1-2, 1-3), preferential neurite extension of PC 12 cells along the long arm direction was achieved. Such anisotropic neurites guidance was further strengthened when the intersection angles were reduced from 90° to 30°. Secondly, functionalization of PCL micropatterns with graphene oxide and graphitic carbon nitride (g-C3N4), a visible-light photocatalyst, may enable optoelectronic conversion and wireless neural stimulation. As a result, photocatalytic stimulation further enhanced neurite extension length under visible light irradiation. Last but not the least, NGC were successfully obtained either by manually rolling or self-assembly using a thermo-responsive bi-layer system. Interestingly, the anisotropic micropattern design dictated the self-assembly process, and an underlying mechanism was proposed. With a synergy of three unique design parameters, the herein presented NGCs may possess great potential for repairing peripheral nerve injuries.


Assuntos
Regeneração Tecidual Guiada , Traumatismos dos Nervos Periféricos , Animais , Anisotropia , Axônios , Regeneração Nervosa , Ratos
17.
J Phys Condens Matter ; 32(40): 404005, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32434171

RESUMO

We demonstrate how image recognition and reinforcement learning combined may be used to determine the atomistic structure of reconstructed crystalline surfaces. A deep neural network represents a reinforcement learning agent that obtains training rewards by interacting with an environment. The environment contains a quantum mechanical potential energy evaluator in the form of a density functional theory program. The agent handles the 3D atomistic structure as a series of stacked 2D images and outputs the next atom type to place and the atomic site to occupy. Agents are seen to require 1000-10 000 single point density functional theory evaluations, to learn by themselves how to build the optimal surface reconstructions of anatase TiO2(001)-(1 × 4) and rutile SnO2(110)-(4 × 1).

18.
Phys Chem Chem Phys ; 22(17): 9204-9209, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32232248

RESUMO

Light weight and cheap electrolytes with fast multi-valent ion conductivity can pave the way for future high-energy density solid-state batteries, beyond the lithium-ion battery. Here we present the mechanism of Mg-ion conductivity of monoammine magnesium borohydride, Mg(BH4)2·NH3. Density functional theory calculations (DFT) reveal that the neutral molecule (NH3) in Mg(BH4)2·NH3 is exchanged between the lattice and interstitial Mg2+ facilitated by a highly flexible structure, mainly owing to a network of di-hydrogen bonds, N-Hδ+-δH-B and the versatile coordination of the BH4- ligand. DFT shows that di-hydrogen bonds in inorganic matter and hydrogen bonds in bio-materials have similar bond strengths and bond lengths. As a result of the high structural flexibiliy, the Mg-ion conductivity is dramatically improved at moderate temperature, e.g. σ(Mg2+) = 3.3 × 10-4 S cm-1 at T = 80 °C for Mg(BH4)2·NH3, which is approximately 8 orders of magnitude higher than that of Mg(BH4)2. Our results may inspire a new approach for the design and discovery of unprecedented multivalent ion conductors.

19.
Chem Commun (Camb) ; 56(28): 3971-3974, 2020 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-32152608

RESUMO

Hemiammine lithium borohydride, LiBH4·1/2NH3, is characterized and a new Li+ conductivity mechanism is identified. It exhibits a Li+ conductivity of 7 × 10-4 S cm-1 at 40 °C in the solid state and 3.0 × 10-2 S cm-1 at 55 °C after melting. The molten state of LiBH4·1/2NH3 has a high viscosity and can be mechanically stabilized in nano-composites with inert metal oxides and other hydrides making it a promising battery electrolyte.

20.
Phys Rev Lett ; 123(24): 240602, 2019 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-31922869

RESUMO

In the path integral formulation of the evolution of an open quantum system coupled to a Gaussian, noninteracting environment, the dynamical contribution of the latter is encoded in an object called the influence functional. Here, we relate the influence functional to the process tensor-a more general representation of a quantum stochastic process-describing the evolution. Then, we use this connection to motivate a tensor network algorithm for the simulation of multitime correlations in open systems, building on recent work where the influence functional is represented in terms of time evolving matrix product operators. By exploiting the symmetries of the influence functional, we are able to use our algorithm to achieve orders-of-magnitude improvement in the efficiency of the resulting numerical simulation. Our improved algorithm is then applied to compute exact phonon emission spectra for the spin-boson model with strong coupling, demonstrating a significant divergence from spectra derived under commonly used assumptions of memorylessness.

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