Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32
Filtrar
1.
Nature ; 626(8000): 759-764, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38383622

RESUMO

The fractional quantum anomalous Hall effect (FQAHE), the analogue of the fractional quantum Hall effect1 at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking2-6. The demonstration of FQAHE could lead to non-Abelian anyons that form the basis of topological quantum computation7-9. So far, FQAHE has been observed only in twisted MoTe2 at a moiré filling factor v > 1/2 (refs. 10-13). Graphene-based moiré superlattices are believed to host FQAHE with the potential advantage of superior material quality and higher electron mobility. Here we report the observation of integer and fractional QAH effects in a rhombohedral pentalayer graphene-hBN moiré superlattice. At zero magnetic field, we observed plateaus of quantized Hall resistance [Formula: see text] at v = 1, 2/3, 3/5, 4/7, 4/9, 3/7 and 2/5 of the moiré superlattice, respectively, accompanied by clear dips in the longitudinal resistance Rxx. Rxy equals [Formula: see text] at v = 1/2 and varies linearly with v, similar to the composite Fermi liquid in the half-filled lowest Landau level at high magnetic fields14-16. By tuning the gate-displacement field D and v, we observed phase transitions from composite Fermi liquid and FQAH states to other correlated electron states. Our system provides an ideal platform for exploring charge fractionalization and (non-Abelian) anyonic braiding at zero magnetic field7-9,17-19, especially considering a lateral junction between FQAHE and superconducting regions in the same device20-22.

2.
Proc Natl Acad Sci U S A ; 121(35): e2321633121, 2024 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-39172784

RESUMO

α-synuclein (α-syn) assembles into structurally distinct fibril polymorphs seen in different synucleinopathies, such as Parkinson's disease and multiple system atrophy. Targeting these unique fibril structures using chemical ligands holds diagnostic significance for different disease subtypes. However, the molecular mechanisms governing small molecules interacting with different fibril polymorphs remain unclear. Here, we investigated the interactions of small molecules belonging to four distinct scaffolds, with different α-syn fibril polymorphs. Using cryo-electron microscopy, we determined the structures of these molecules when bound to the fibrils formed by E46K mutant α-syn and compared them to those bound with wild-type α-syn fibrils. Notably, we observed that these ligands exhibit remarkable binding adaptability, as they engage distinct binding sites across different fibril polymorphs. While the molecular scaffold primarily steered the binding locations and geometries on specific sites, the conjugated functional groups further refined this adaptable binding by fine-tuning the geometries and binding sites. Overall, our finding elucidates the adaptability of small molecules binding to different fibril structures, which sheds light on the diagnostic tracer and drug developments tailored to specific pathological fibril polymorphs.


Assuntos
Amiloide , Microscopia Crioeletrônica , alfa-Sinucleína , alfa-Sinucleína/metabolismo , alfa-Sinucleína/química , Amiloide/metabolismo , Amiloide/química , Ligantes , Humanos , Sítios de Ligação , Ligação Proteica , Doença de Parkinson/metabolismo , Mutação
3.
Nano Lett ; 24(23): 6931-6938, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38804717

RESUMO

Spin-orbit torque magnetic random access memory (SOT-MRAM) has great promise in high write speed and low power consumption. Mo can play a vital role in constructing a CoFeB/MgO-based MRAM cell because of its ability to enhance the perpendicular magnetic anisotropy (PMA), thermal tolerance, and tunneling magnetoresistance. However, Mo is often considered as a less favorable candidate among SOT materials because of its weak spin-orbit coupling. In this study, we experimentally investigate the SOT efficiencies in Mo/CoFeB/MgO heterostructures over a wide range of Mo thicknesses and temperature. Decent damping-like SOT efficiency |ξDL| = 0.015 ± 0.001 and field-like SOT efficiency |ξFL| = 0.050 ± 0.001 are found in amorphous Mo. The ξFL/ξDL ratio is greater than 3. Furthermore, efficient current-induced magnetization switching is demonstrated with the critical current density comparable with heavy metal Ir and W. Our work reveals new understanding and possibilities for Mo as both an SOT source component and PMA buffer layer in the implementation of SOT-MRAMs.

4.
J Chem Phys ; 161(7)2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39145552

RESUMO

In this work, we use a Bayesian optimization (BO) algorithm to sample the space of covalent organic framework (COF) components aimed at the design of COFs with a high hole conductivity. COFs are crystalline, often porous coordination polymers, where organic molecular units-called building blocks (BBs)-are connected by covalent bonds. Even though we limit ourselves here to a space of three-fold symmetric BBs forming two-dimensional COF sheets, their design space is still much too large to be sampled by traditional means through evaluating the properties of each element in this space from first principles. In order to ensure valid BBs, we use a molecular generation algorithm that, by construction, leads to rigid three-fold symmetric molecules. The BO approach then trains two distinct surrogate models for two conductivity properties, level alignment vs a reference electrode and reorganization free energy, which are combined in a fitness function as the objective that evaluates BBs' conductivities. These continuously improving surrogates allow the prediction of a material's properties at a low computational cost. It thus allows us to select promising candidates which, together with candidates that are very different from the molecules already sampled, form the updated training sets of the surrogate models. In the course of 20 such training steps, we find a number of promising candidates, some being only variations on already known motifs and others being completely novel. Finally, we subject the six best such candidates to a computational reverse synthesis analysis to gauge their real-world synthesizability.

5.
Nephrol Dial Transplant ; 39(1): 55-63, 2023 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-37391382

RESUMO

BACKGROUND: In chronic kidney disease, current guidelines recommend systolic blood pressure (SBP) below 120 mmHg. However, the renoprotective effect of intensive blood-pressure (BP) lowering on immunoglobulin A nephropathy (IgAN) remains undetermined. We aimed to determine the effect of intensive BP control on the progression of IgAN. METHODS: At Peking University First Hospital, 1530 patients with IgAN were enrolled. An examination of the relationship between baseline and time-updated BP and composite kidney outcomes, defined as development of end-stage kidney disease (ESKD) or a 30% decline in estimated glomerular filtration rate (eGFR), was conducted. Baseline and time-updated BPs were modeled using multivariate causal hazards models and marginal structural models (MSMs). RESULTS: In a median follow-up of 43.5 (interquartile range 27.2, 72.7) months, 367 (24.0%) patients experienced the composite kidney outcomes. No significant associations were found between baseline BP and the composite outcomes. Using MSMs with time-updated SBP for analysis, a U-shaped association was found. In reference to SBP 110-119 mmHg, hazard ratios (95% confidence intervals) for the SBP categories <110, 120-129, 130-139 and ≥140 mmHg were 1.48 (1.02-2.17), 1.13 (0.80-1.60), 2.21 (1.54-3.16) and 2.91 (1.94-4.35), respectively. The trend was more prominent in patients with proteinuria ≥1 g/day and eGFR ≥60 mL/min/1.73 m2. After analyzing time-updated diastolic BP, no similar trend was observed. CONCLUSIONS: In patients with IgAN, intensive BP control during the treatment period may retard the kidney disease progression, but the potential risk of hypotension still needs to be considered.


Assuntos
Glomerulonefrite por IGA , Falência Renal Crônica , Insuficiência Renal Crônica , Humanos , Estudos de Coortes , Glomerulonefrite por IGA/complicações , Pressão Sanguínea/fisiologia , Rim , Insuficiência Renal Crônica/complicações , Falência Renal Crônica/etiologia , Progressão da Doença , Taxa de Filtração Glomerular
6.
Br J Nutr ; 129(10): 1714-1731, 2023 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-35945656

RESUMO

In this study, we conducted a meta-analysis to estimate the relationship between the consumption of dairy products and the risk of prostate cancer. We searched PubMed, Embase and Cochrane databases for relevant articles and identified a total of thirty-three cohort studies between 1989 and 2020. The qualities of included studies were assessed using Newcastle-Ottawa scale. Pooled adjusted relative risks (RR) with 95 % CI were calculated. We performed subgroup analyses stratified by dairy type, prostate cancer type, follow-up years, treatment era, collection times, adjustment for confounders and geographic location. In the subgroup analysis stratified by prostate cancer type, the pooled RR were 0·98 (95 % CI 0·94, 1·03) in the advanced group, 1·10 (95 % CI 0·98, 1·24) in the non-advanced group and 0·92 (95 % CI 0·84, 1·00) in the fatal group. In the dose-response analysis, a positive association for the risk of prostate cancer was observed for total dairy products 400 g/d (RR: 1·02; 95 % CI 1·00, 1·03), total milk 200 g/d (RR: 1·02; 95 % CI 1·01, 1·03), cheese 40 g/d (RR: 1·01; 95 % CI 1·00, 1·03) and butter 50 g/d (RR: 1·03; 95 % CI 1·01, 1·05). A decreased risk was observed for the intake of whole milk 100 g/d (RR: 0·97; 95 % CI 0·96, 0·99). Our meta-analysis suggests that high intakes of dairy products may be associated with an increased risk of prostate cancer; however, since many of the studies were affected by prostate-specific antigen (PSA) screening bias, additional studies with an adjustment of PSA screening are needed.


Assuntos
Queijo , Neoplasias da Próstata , Masculino , Humanos , Animais , Antígeno Prostático Específico , Dieta/efeitos adversos , Laticínios/efeitos adversos , Leite , Neoplasias da Próstata/epidemiologia , Neoplasias da Próstata/etiologia , Fatores de Risco
7.
Dig Dis Sci ; 68(5): 1894-1912, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36459296

RESUMO

BACKGROUND: Pancreatic adenocarcinoma (PAAD) is a malignant tumor responsible for a heavy disease burden. Previously, only one pan-cancer study of Transmembrane channel-like protein 5 (TMC5) showed that TMC5 was highly expressed in PAAD, but the results lacked comprehensive verification, and the mechanism of TMC5 in PAAD was still unclear. METHODS: For exploring the expression and clinical value of TMC5 in PAAD better, we adopted a comprehensive evaluation method, using internal immunohistochemistry (IHC) data combined with microarray and RNA-sequencing data collected from public databases. The single cell RNA-sequencing (scRNA-seq) data were exploited to explore the TMC5 expression in cell populations and intercellular communication. The potential mechanism of TMC5 in PAAD was analyzed from the aspects of immune infiltration, transcriptional regulation, function and pathway enrichment. RESULTS: Our IHC data includes 148 PAAD samples and 19 non-PAAD samples, along with the available microarray and RNA-sequencing data (1166 PAAD samples, 704 non-PAAD samples). The comprehensive evaluation results showed that TMC5 was evidently up-regulated in PAAD (SMD = 1.17). Further analysis showed that TMC5 was over-expressed in cancerous epithelial cells. Furthermore, TMC5 was up-regulated in more advanced tumor T and N stages. Interestingly, we found that STAT3 as an immune marker of Th17 cells was not only positively correlated with TMC5 and up-regulated in PAAD tissues, but also the major predicted TMC5 transcription regulator. Moreover, STAT3 was involved in cancer pathway of PAAD. CONCLUSION: Up-regulated TMC5 indicates advanced tumor stage in PAAD patients, and its role in promoting PAAD development may be regulated by STAT3.


Assuntos
Adenocarcinoma , Neoplasias Pancreáticas , Humanos , Adenocarcinoma/genética , Neoplasias Pancreáticas/genética , Comunicação Celular , Efeitos Psicossociais da Doença , Prognóstico , Regulação Neoplásica da Expressão Gênica , Neoplasias Pancreáticas
8.
J Ind Microbiol Biotechnol ; 50(1)2023 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-37942557

RESUMO

The off-flavor of Pichia pastoris strains is a negative characteristic of proteins overexpressed with this yeast. In the present study, P. pastoris GS115 overexpressing an α-l-rhamnosidase was taken as the example to characterize the off-flavor via sensory evaluation, gas chromatography-mass spectrometer, gas chromatography-olfaction, and omission test. The result showed that the off-flavor was due to the strong sweaty note, and moderate metallic and plastic notes. Four volatile compounds, that is, tetramethylpyrazine, 2,4-di-tert-butylphenol, isovaleric acid, and 2-methylbutyric acid, were identified to be major contributors to the sweaty note. Dodecanol and 2-acetylbutyrolactone were identified to be contributors to the metallic and plastic notes, respectively. It is the first study on the off-flavor of P. pastoris strains, helping understand metabolites with off-flavor of this yeast. Interestingly, it is the first study illustrating 2-acetylbutyrolactone and dodecanol with plastic and metallic notes, providing new information about the aromatic contributors of biological products. IMPORTANCE: The methylotrophic yeast Pichia pastoris is an important host for the industrial expression of functional proteins. In our previous studies, P. pastoris strains have been sniffed with a strong off-flavor during the overexpression of various functional proteins, limiting the application of these proteins. Although many yeast strains have been reported with off-flavor, no attention has been paid to characterize the off-flavor in P. pastoris so far. Considering that P. pastoris has advantages over other established expression systems of functional proteins, it is of interest to identify the compounds with off-flavor synthesized in the overexpression of functional proteins with P. pastoris strains. In this study, the off-flavor synthesized from P. pastoris GS115 was characterized during the overexpression of an α-l-rhamnosidase, which helps understand the aromatic metabolites with off-flavor of P. pastoris strains. In addition, 2-acetylbutyrolactone and dodecanol were newly revealed with plastic and metallic notes, enriching the aromatic contributors of biological products. Thus, this study is important for understanding the metabolites with off-flavor of P. pastoris strains and other organisms, providing important knowledge to improve the flavor of products yielding with P. pastoris strains and other organisms. ONE-SENTENCE SUMMARY: Characterize the sensory and chemical profile of the off-flavor produced by one strain of P. pastoris in vitro.


Assuntos
Produtos Biológicos , Saccharomyces cerevisiae , Pichia/genética , Pichia/metabolismo , Produtos Biológicos/metabolismo , Dodecanol/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
9.
Nephrology (Carlton) ; 27(2): 155-161, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34713949

RESUMO

AIM: Hydroxychloroquine (HCQ) is used to control proteinuria in IgA Nephropathy (IgAN) However, its efficacy and safety in pregnant IgAN patients remains unknown. This study aimed to verify the safety of HCQ in pregnant IgAN patients and compare renal function and pregnancy outcomes with those of patients not treated with HCQ. METHODS: We retrospectively reviewed medical records of all pregnant IgAN patients and singleton gestations at Peking University First Hospital from 2003-2021. Patients who did and did not receive HCQ treatment during pregnancy were compared. RESULTS: We found no significant pre- or post-pregnancy differences in proteinuria or renal function between the two groups. However, the HCQ (+) group had higher proteinuria at the time of kidney biopsy (2.04 [1.26, 2.56] g/d vs. 0.80 [0.44, 1.11] g/d, P < .001); the proteinuria level at HCQ therapy initiation was also higher than that at the beginning of pregnancy (1.87 [1.30, 2.59] g/d vs. 1.08 [0.75, 1.50] g/d, P = .001). Despite no difference in preterm birth, birth weight, preeclampsia or postpartum haemorrhage, the proportion of patients with a previous history of spontaneous abortion was higher in the HCQ (+) group than in the HCQ (-) group (48.0% vs. 20.6%, P = .010). The eGFR (regression coefficient, 0.981; 95%CI 0.964-0.998) was a predictive factor for obstetrical complications. CONCLUSION: HCQ is safe for IgAN treatment during pregnancy with effective reduction of proteinuria. HCQ might also be helpful in patients with a history of spontaneous abortion.


Assuntos
Glomerulonefrite por IGA/tratamento farmacológico , Hidroxicloroquina/uso terapêutico , Complicações na Gravidez/tratamento farmacológico , Adulto , Estudos de Coortes , Feminino , Glomerulonefrite por IGA/fisiopatologia , Humanos , Hidroxicloroquina/efeitos adversos , Testes de Função Renal , Gravidez , Resultado da Gravidez , Estudos Retrospectivos , Resultado do Tratamento
10.
BMC Nephrol ; 23(1): 269, 2022 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-35896958

RESUMO

BACKGROUND: There are few studies on immunoglobulin A nephropathy (IgAN) at high altitude. This study aimed to analyze the clinical and pathological characteristics of IgAN between Tibet and Beijing, which provided a basis for improving diagnosis and treatment in Tibet. METHOD: The clinical and pathological data of 80 patients from the People's Hospital of Tibet Autonomous Region (Tibetan group) and 991 patients from Peking University First Hospital (Beijing group) with IgAN proven by renal biopsy were compared retrospectively between January 2016 and July 2020. The kidney biopsy tissue was sent to the Department of Nephrology, Peking University First Hospital for pathological evaluation. RESULTS: The proteinuria (2.9 [2.0, 4.9] vs. 1.1 [0.5, 2.4] g/day, P < 0.001) in the Tibetan group was significantly higher than that in the Beijing group. The serum albumin (30.4 ± 7.7 vs. 38.2 ± 5.5 g/L, P < 0.001) was significantly lower in the Tibetan group. The eGFR (77.7 ± 37.8 vs. 62.1 ± 33.6 ml/min/1.73 m2, P = 0.001) was higher in the Tibetan group. The percentage of patients with nephrotic syndrome in the Tibetan group was significantly higher than that in the Beijing group (33.8% vs. 4.7%, P < 0.001). CONCLUSION: There are differences in the clinical and pathological characteristics of IgAN between plateau and plain regions.


Assuntos
Glomerulonefrite por IGA , Síndrome Nefrótica , Glomerulonefrite por IGA/diagnóstico , Glomerulonefrite por IGA/epidemiologia , Glomerulonefrite por IGA/patologia , Humanos , Síndrome Nefrótica/epidemiologia , Proteinúria , Estudos Retrospectivos , Tibet/epidemiologia
11.
J Chem Phys ; 154(7): 074115, 2021 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-33607905

RESUMO

We compare algorithms to sample initial positions and momenta of a molecular system for classical trajectory simulations. We aim at reproducing the phase space quantum distribution for a vibrational eigenstate, as in Wigner theory. Moreover, we address the issue of controlling the total energy and the energy partition among the vibrational modes. In fact, Wigner's energy distributions are very broad, quite at variance with quantum eigenenergies. Many molecular processes depend sharply on the available energy, so a better energy definition is important. Two approaches are introduced and tested: the first consists in constraining the total energy of each trajectory to equal the quantum eigenenergy. The second approach modifies the phase space distribution so as to reduce the deviation of the single mode energies from the correct quantum values. A combination of the two approaches is also presented.

12.
Sensors (Basel) ; 21(5)2021 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-33671072

RESUMO

Edge computing (EC) has recently emerged as a promising paradigm that supports resource-hungry Internet of Things (IoT) applications with low latency services at the network edge. However, the limited capacity of computing resources at the edge server poses great challenges for scheduling application tasks. In this paper, a task scheduling problem is studied in the EC scenario, and multiple tasks are scheduled to virtual machines (VMs) configured at the edge server by maximizing the long-term task satisfaction degree (LTSD). The problem is formulated as a Markov decision process (MDP) for which the state, action, state transition, and reward are designed. We leverage deep reinforcement learning (DRL) to solve both time scheduling (i.e., the task execution order) and resource allocation (i.e., which VM the task is assigned to), considering the diversity of the tasks and the heterogeneity of available resources. A policy-based REINFORCE algorithm is proposed for the task scheduling problem, and a fully-connected neural network (FCN) is utilized to extract the features. Simulation results show that the proposed DRL-based task scheduling algorithm outperforms the existing methods in the literature in terms of the average task satisfaction degree and success ratio.

13.
Microb Pathog ; 138: 103846, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31698051

RESUMO

Acute lung injury (ALI) is a serious respiratory syndrome featured with uncontrolled inflammatory response. Biochanin A has been showed to possess and anti-inflammatory effect. This study intended to explore the suppression of biochanin A on lipopolysaccharide (LPS)-induced ALI in mice. Seven hours later LPS-induced ALI model established, the indexes including, pathological changes, MPO activity, wet/dry ratio, proinflammatory cytokines TNF-α, IL-1ß, and IL-6, production, as well as and TLR4/NF-κB and PPAR-γ signaling pathway expression were compared bwtween different groups. In addition, bronchoalveolar lavage fluid (BALF) was collected and the levels of total protein, inflammatory cells and TNF-α, IL-1ß, and IL-6 were detected. The results revealed that LPS lead to significantly lung pathological injury, and damage of lung vascular permeability showing by higher lung wet/dry ratio and total protein levels in the BALF when compared to the control group mice. However, these changes significantly reversed by biochanin A. Moreover, the levels of inflammatory cells in BALF, proinflammatory cytokines TNF-α, IL-1ß, and IL-6, in both lung and BALF were also dose-dependently reduced by biochanin A during ALI process. To investigate the anti-inflammatory mechanisms of biochanin A, we found that biochanin A significantly inhibited the activation of TLR4/NF-κB signaling pathway induced by LPS. Furthermore, the expression of PPAR-γ also markedly increased in the mice after treated with biochanin A. In conclusion, biochanin A alleviated LPS-induced ALI by inhibiting the inflammatory response, which was mediated via down-regulating the activation of TLR4/NF-κB signaling pathway and enhancing the expression of PPAR-γ.


Assuntos
Lesão Pulmonar Aguda/imunologia , Genisteína/farmacologia , Lipopolissacarídeos/administração & dosagem , Pneumonia/tratamento farmacológico , Lesão Pulmonar Aguda/metabolismo , Animais , Anti-Inflamatórios/farmacologia , Camundongos , NF-kappa B/metabolismo , PPAR gama/metabolismo , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/metabolismo
14.
J Phys Chem A ; 124(9): 1821-1828, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32024358

RESUMO

The 3CH2 + 3O2 reaction has a quite complex ground state singlet potential energy surface (PES). There are multiple minima and transition states before forming the 10 possible reaction products. A previous direct chemical dynamics simulation at the UM06/6-311++G(d,p) level of theory ( J. Phys. Chem. A 2019, 123, 4360-4369) found that reaction on this PES is predominantly direct without trapping in the potential minima. The first minima 3CH2 + 3O2 encounters is that for the 1CH2O2 Criegee intermediate and statistical theory assumes the reactive system is trapped in this intermediate with a lifetime given by Rice-Ramsperger-Kassel-Marcus (RRKM) theory. In the work presented here, a direct dynamics simulation is performed with the above UM06 theory, with the trajectories initialized in the 1CH2O2 intermediate with a random distribution of vibrational energy as assumed by RRKM theory. There are substantial differences between the dynamics for 1CH2O2 dissociation and 3CH2 + 3O2 reaction. For the former there are four product channels, while for the latter there are seven in agreement with experiment. Product energy partitioning for the two simulations are in overall good agreement for the CO2 + H2 and CO + H2O product channels, but in significant disagreement for the HCO + OH product channel. Though 1CH2O2 is excited randomly in accord with RRKM theory, its dissociation probability is biexponential and not exponential as assumed by RRKM. In addition, the 1CH2O2 dissociation dynamics follow non-intrinsic reaction coordinate (non-IRC) pathways. An important finding is that the nonstatistical dynamics for the 3CH2 + 3O2 reaction give results in agreement with experiment.

15.
J Phys Chem A ; 124(20): 4062-4067, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32352296

RESUMO

Quasi-classical direct dynamics simulations, performed with the B3LYP-D3/cc-pVDZ electronic structure theory, are reported for vibrational relaxation of the three NH stretches of the -NH3+ group of protonated tryptophan (TrpH+), excited to the n = 1 local mode states. The intramolecular vibrational energy relaxation (IVR) rates determined for these states, from the simulations, are in good agreement with the experiment. In accordance with the experiment, IVR for the free NH stretch is slowest, with faster IVR for the remaining two NH stretches which have intermolecular couplings with an O atom and a benzenoid ring. For the free NH and the NH coupled to the benzenoid ring, there are beats (i.e., recurrences) in their relaxations versus time. For the free NH stretch, 50% of the population remained in n = 1 when the trajectories were terminated at 0.4 ps. IVR for the free NH stretch is substantially slower than for the CH stretch in benzene. The agreement found in this study between quasi-classical direct dynamics simulations and experiments indicates the possible applicability of this simulation method to larger biological molecules. Because IVR can drive or inhibit reactions, calculations of IVR time scales are of interest, for example, in unimolecular reactions, mode-specific chemistry, and many photochemical processes.

16.
Med Sci Monit ; 26: e922854, 2020 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-32529991

RESUMO

BACKGROUND Oral squamous cell carcinoma (OSCC) is the sixth most prevalent cancer worldwide, with low 5-year survival rate. To identify novel prognostic markers for OSCC and determine the immune and stromal landscape of OSCC, a risk signature for OSCC patients was constructed in this study. MATERIAL AND METHODS Immune and stromal scores for OSCC samples from the Genomic Data Commons Data Portal were computed to delineate the tumor microenvironment landscape of oral cancer based on the Estimation of STromal and Immune cells in MAlignant Tumours using Expression data algorithm. An immune score-based risk signature was constructed by combining random forest and support vector machine methods. Correlation analysis of risk signature gene expression and immune cell infiltration was conducted, and the distinguishing power of individual signature genes was evaluated by analyzing receiver operating characteristics (ROC) curves. Differentially enriched pathways between high and low risk groups were investigated via gene set variation analysis. ROC curves were plotted for signature genes to examine their ability to distinguish the recurrence and survival status of OSCC patients from GSE84846. RESULTS An immune score-related risk signature composed of ARMH1, F2RL2, AC004687.1, COL6A5, AC008750.1, RAB19, CRLF2, GRIP2, and FAM162B performed well in the prognostic stratification of OSCC patients and could effectively distinguish their survival status. Lists of pathways, including cytokine-cytokine receptor interaction and cell adhesion molecules displayed remarkable differential enrichment between high and low risk OSCC patients. CONCLUSIONS An immune score-based risk signature constructed presently may be useful to decide appropriate treatment options for individual OSCC patients.


Assuntos
Neoplasias Bucais/genética , Neoplasias Bucais/imunologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Carcinoma de Células Escamosas de Cabeça e Pescoço/imunologia , Citocinas/genética , Citocinas/imunologia , Bases de Dados Genéticas , Feminino , Perfilação da Expressão Gênica , Humanos , Sistema Imunitário/citologia , Sistema Imunitário/imunologia , Linfócitos do Interstício Tumoral , Masculino , Análise Multivariada , Prognóstico , Modelos de Riscos Proporcionais , Mapas de Interação de Proteínas , RNA Mensageiro , RNA-Seq , Curva ROC , Receptores de Citocinas/genética , Receptores de Citocinas/imunologia , Medição de Risco , Máquina de Vetores de Suporte , Transcriptoma , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia
18.
RSC Adv ; 14(18): 12873-12882, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38650691

RESUMO

In order to solve the environmental damage caused by the discharge of dyes as industrial wastewater, the development of efficient and sustainable adsorbents is the key, while most of the previous studies on bamboo parenchyma cells have focused on their microstructural, functional and mechanical properties, and few of the properties in adsorption have been investigated. To evaluate the role of the unique microstructure of bamboo parenchyma cells on adsorption after carbonization and activation, PC-based activated carbon (PPAC) was fabricated by the phosphoric acid activation method and tested for adsorption using methylene blue (MB). The effect of mesoporous structure on MB adsorption was investigated in detail using PPAC-30C impregnated with phosphoric acid at a concentration of 30%. The results showed that the adsorption performance was influenced by single-factor experiments (e.g., pH, activated carbon dosing). The adsorption isotherms and kinetics could conform to the Langmuir model (R2 = 0.983-0.994) and pseudo-second-order kinetic model (R2 = 0.822-0.991) respectively, and the maximum MB adsorption capacity of adsorbent was 576 mg g-1. The adsorption mechanism of MB on PPAC-30C includes physical adsorption, electrostatic attraction, hydrogen bonding, and the π-π conjugation effect, which was dominated by physical adsorption. The results of this study show that PPAC has good application prospects for cationic dye removal.

19.
Science ; 384(6696): 647-651, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38723084

RESUMO

The quantum anomalous Hall effect (QAHE) is a robust topological phenomenon that features quantized Hall resistance at zero magnetic field. We report the QAHE in a rhombohedral pentalayer graphene-monolayer tungsten disulfide (WS2) heterostructure. Distinct from other experimentally confirmed QAHE systems, this system has neither magnetic element nor moiré superlattice effect. The QAH states emerge at charge neutrality and feature Chern numbers C = ±5 at temperatures of up to about 1.5 kelvin. This large QAHE arises from the synergy of the electron correlation in intrinsic flat bands of pentalayer graphene, the gate-tuning effect, and the proximity-induced Ising spin-orbit coupling. Our experiment demonstrates the potential of crystalline two-dimensional materials for intertwined electron correlation and band topology physics and may enable a route for engineering chiral Majorana edge states.

20.
Rev Sci Instrum ; 94(7)2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37432097

RESUMO

The study of interface spin effects in spintronic multilayer films requires distinguishing the effects generated by different interfaces. However, testing in atmospheric conditions requires a capping layer to protect the films, which introduces new interfaces and limits the study of interface spin-dependent effects. To address this challenge, we have developed an integrated ultra-high vacuum cluster system that includes magnetron sputtering equipment, ion irradiation equipment, and time-resolved magneto-optical Kerr effect (TR-MOKE) equipment. Our sputtering system integrates 12 cathodes in a single chamber, allowing the co-sputtering of four targets. The ultimate vacuum can reach 1 × 10-10 mbar, and the deposition resolution of 0.1 nm can be achieved. Ion irradiation equipment can ionize to produce He+, and by screening and accelerating the implantation of He+ into multilayer films, ion scanning is realized, and up to 30 keV energy can be applied to the films. The TR-MOKE equipment can detect ultra-fast magnetic dynamics processes in vacuum conditions, and its external magnetic field can be rotated 360°. Our vacuum cluster system connects the three subsystems, allowing in situ film deposition, regulation, and characterization. By accurately detecting the effects of different layers, the system can distinguish the interface effects of multilayers. Experimental results demonstrate that the three subsystems can work independently or coordinate to observe the interface effects of multilayers.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA