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1.
Zhonghua Yan Ke Za Zhi ; 59(1): 52-56, 2023 Jan 11.
Artigo em Chinês | MEDLINE | ID: mdl-36631059

RESUMO

A male patient presented to department of ophthalmology for progressive left eye blurred vision with visual deformation for 1 month. Imaging findings were typical intraocular lymphoma infiltration, and head MRI and positron emission tomography-CT showed no mass in other parts of the body. After review of the medical history, the patient first presented with extrocular signs such as lacrimal gland enlargement, eyeball protrusion and extraocular myoedema, without any abnormal changes in the fundus. Combined with the history, the patient was diagnosed as a binocular primary accessory mantle cell lymphoma with intraocular infiltration. After 9 months of systemic treatment with rituximab combined with zbrutinib, the patient's binocular visual acuity was significantly improved and the intraocular and intraocular manifestations disappeared.


Assuntos
Neoplasias Oculares , Aparelho Lacrimal , Linfoma de Célula do Manto , Humanos , Masculino , Adulto , Linfoma de Célula do Manto/diagnóstico , Linfoma de Célula do Manto/patologia , Linfoma de Célula do Manto/terapia , Rituximab , Neoplasias Oculares/diagnóstico , Aparelho Lacrimal/patologia
2.
Zhonghua Fu Chan Ke Za Zhi ; 56(7): 474-481, 2021 Jul 25.
Artigo em Chinês | MEDLINE | ID: mdl-34304439

RESUMO

Objective: To investigate the impact of trigger timing of gonadotropin- releasing hormone (GnRH) antagonist regimen for infertility patients of various ages. Methods: This was a retrospective study, 1 529 infertility patients who receiving GnRH antagonist regimen in Chongqing Health Center for Women and Children from January 2017 to December 2018 were divided into the advance trigger group and the standard trigger group, and further divided into three subgroups according to age:<35 years, 35-40 years,>40 years. The number of retrieved oocytes and transplantable embryos, the clinical pregnancy rate and the live birth rate among patients in the advance trigger group and standard trigger group in various age subgroups were compared. Results: (1) The gonadotropin (Gn) days among the three age subgroups were significantly shorter in the advance trigger group compared to the same-aged standard trigger group (all P<0.01), but only in the 35-40 years and >40 years subgroups, the Gn doses in the advance trigger group [(2 702±551) and (2 780±561) U] were significantly less than those in the standard trigger group (all P<0.01). In the <35 years subgroup, the number of oocytes retrieved and transplantable embryos of the advance trigger group (6.6±4.8 and 2.6±2.7) were significantly less than those of the standard trigger group (all P<0.01), but there was no difference in the number of top-quality embryos (P=0.580); however, in the 35-40 years and >40 years subgroups, there were no significant differences between advance and standard trigger groups in terms of the afore mentioned 3 indicators (all P>0.05), only the numbers of top-quality embryos in the advance trigger group (0.6±1.0 and 0.6±0.9) were significantly higher than those in the standard trigger group (all P<0.01). (2) In the <35 years and 35-40 years subgroups, no significant differences were noted between the advance trigger group and standard trigger group with regard to the clinical pregnancy rate and live birth rate (all P>0.05); but in the >40 years subgroup, the clinical pregnancy rate of the advance trigger group was significantly higher than that of the standard trigger group [33.0% (30/91) vs 19.2% (25/130), P=0.020], and there was no statistical difference in the live birth rate (P=0.064). (3) Multivariate logistic regression analysis showed that trigger timing was an independent predictor of clinical pregnancy rate in the >40 years subgroup (OR=0.334, 95%CI: 0.119-0.937, P=0.037), but not an independent predictor of live birth rate (P>0.05). Conclusions: Advance trigger in the GnRH antagonist protocol for infertility patients >40 years old could effectively reduce Gn times and Gn dosage, increase the number of top-quality embryos, and improve the clinical pregnancy rate. Therefore, compared with patients ≤40 years of age, patients >40 years might benefit more from advance trigger.


Assuntos
Infertilidade , Indução da Ovulação , Adulto , Feminino , Fertilização in vitro , Hormônio Liberador de Gonadotropina , Humanos , Gravidez , Taxa de Gravidez , Estudos Retrospectivos
3.
Zhonghua Yu Fang Yi Xue Za Zhi ; 52(11): 1158-1163, 2018 Nov 06.
Artigo em Chinês | MEDLINE | ID: mdl-30419701

RESUMO

Objectives: To explore the expression regulation of type 1 and type 2 (Th1 and Th2) cytokines from serum of coal miners and the evaluation in surveillance of coal workers' pneumoconiosis, 630 coal miners were studied. Methods: A total of 90 male patients diagnosed as coal workers' pneumoconiosis (CWP) in a institute for occupational health and 19 male workers newly diagnosed as CWP patients was chosen as CWP group with simple random sampling method from a coal mine group from January 2013 to December in 2015. 180 male coal miners with abnormal but not diagnosed as CWP were selected as CWP suspected group with simple random sampling methods, meanwhile 180 male coal miners with normal chest X-ray photograph was as dust-exposed group by 1∶1 matched as age. And 161 healthy males accepted pre-employed examination were selected as control group, CWP suspected group, dust-exposed group and control group called as non-CWP group. According to screening test and diagnosis test, the basic information and occupational history of all subjects were collected, and cytokines including IL-1ß, IL-8, IFN-γ, IL-6 and IL-10 of serum were detected. Receiver operator characteristic (ROC) curve was used to determine the optimal cutoff value of each cytokine. Area under curve (AUC), the validity and reliability were calculated and judged. Results: The average age of control group, dust-exposed group, CWP suspected group and CWP group were (27.4±5.0) , (43.4±10.7) , (48.2±6.2) , (64.7±7.0) years old, respectively. The median level of IL-1ß, IL-8, IFN-γ and IL-6 in cases group (1 638.30, 2 099.49, 815.18,140.32 pg/ml) were higher than that of non-cases group (1 445.57, 1 402.26, 736.38, 95.73 pg/ml) (P<0.05) . The level of IL-8 (1 503.99 pg/ml) in CWP suspected group was higher than that of control group (1 295.67 pg/ml) and dust-exposed group (1 376.94 pg/ml) , but the level of IL-10 (654.08 pg/ml) was lower than that of control group (596.64 pg/ml) . The ratio of IFN-γ/IL-6 ranged from 5 to 8, and the ratio in CWP group (5.87) was lower than that of non-CWP group (7.61) . The IL-6 and IL-8 among the subjects of dust-exposed group in terms of the age distribution of among had reached statistical significance. According to ROC, the cutoff value of IL-1ß, IL-6, IL-8, IL-10 and INF-γ reached 1 582.65, 116.53, 1 791.54, 581.08 and 792.69 pg/ml, respectively. The AUC was 0.668, 0.895, 0.859, 0.716 and 0.637, respectively. It was found that IL-6 and IL-8 could be used as biomarkers in detecting CWP, the sensitivity and specificity was 82.6% and 84.6%, 78.0% and 84.8%, respectively; Youden's index was 0.674 and 0.628 and the consistency rate was 84.3% and 83.7%, while Kappa value was 0.55 and 0.52. Conclusion: There was Type 1 and type 2 cytokine dysregulation in CWP patients. IL-6 and IL-8 can be used as effective biomarkers to forecast lung injury before X-ray changes.


Assuntos
Minas de Carvão , Citocinas/sangue , Doenças Profissionais/diagnóstico , Pneumoconiose/diagnóstico , Vigilância da População/métodos , Adulto , Idoso , Biomarcadores/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Profissionais/epidemiologia , Pneumoconiose/epidemiologia , Reprodutibilidade dos Testes
4.
Phys Chem Chem Phys ; 18(24): 16566-74, 2016 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-27253605

RESUMO

The bipolar effect in relatively narrow band-gap thermoelectric (TE) compounds is a negative process deteriorating the TE properties particularly at higher temperatures. In this work, we investigate the TE performance of the compound CaMg2Bi2 using the first-principles calculation and semi-classical Boltzmann transport theory in combination with our experimental data. It is revealed that this compound exhibits a remarkable bipolar effect and temperature-dependent carrier concentration. The bipolar effect imposes remarkable influence on all the electron-transport related TE parameters. An effective carrier concentration neff as a function of temperature is proposed to account for the bipolar effect induced carrier excitations. The as-evaluated TE parameters then show good consistency with measured results. This work may shed light on our understanding of the bipolar effect in TE compounds.

5.
J Prev Alzheimers Dis ; 11(1): 88-96, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38230721

RESUMO

BACKGROUND: Previous studies only focused on changes in the global age-specific incidence and mortality for Alzheimer's disease and other dementias, failed to distinguish between cohort and period effects, and did not discuss risk factors separately. METHODS: In this study, Alzheimer's disease disability-adjusted life years (DALYs) data to estimate the burden by gender, age, locations, and social-demographic status for 21 regions from 1990 to 2019. Additionally, trend analysis was performed using the age-period-cohort (APC) model and Join-point model. RESULTS: In most regions, indicators (incidence, mortality, and DALYs) increased steadily with socio-demographic index(SDI) increased. The age effects for Alzheimer's disease and other dementias showed a significant increase from 40 to 95 years. The cohort effects rate ratios (RRs) had a rapid reduction attributed to smoking, high fasting plasma glucose, and high body mass index (BMI). CONCLUSIONS: Countries in middle-low and low SDI regions have higher levels of risk factor exposure. As a result, rapid and effective government responses are necessary to control dementia risk factors and reduce the disease burden in these countries.


Assuntos
Doença de Alzheimer , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/epidemiologia , Anos de Vida Ajustados por Qualidade de Vida , Carga Global da Doença , Estilo de Vida , Fatores Socioeconômicos
6.
RSC Adv ; 11(5): 3043-3048, 2021 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-35424264

RESUMO

The importance of martensitic transformations has led to tremendous efforts to explore the microscopic martensitic transition paths. There are five possible transformation paths (for γ → α transition) known for Fe at present, and at an arbitrary activation energy, any of the five paths might be followed. It then becomes considerably difficult to monitor the microscopic phase transition mechanism in experiments. Therefore, it is helpful to realize only one of the paths in a physical process. Based on first-principles calculations, we show that at suitable activation energies the Nishiyama-Wassermann (N-W) transformation path can be realized without the involvement of the Bain path, since the condition E NW(θ) < E < E Bain can be satisfied by pure Fe. E is the activation energy of the system, and E NW(θ) and E Bain are the energy barriers for the N-W and Bain transformations, respectively. In particular, the potential energy surface (PES) for the N-W transformation has been calculated as being four-dimensional, i.e., E = E(a,b,c,θ), where (a, b, c) are the lattice constants and θ is the shear angle involved in the shear distortion of the N-W path.

7.
Biophys J ; 99(1): 3-12, 2010 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-20655827

RESUMO

We study Ca(2+) release through single and clustered IP(3) receptor channels on the ER membrane under presence of buffer proteins. Our computational scheme couples reaction-diffusion equations and a Markovian channel model and allows our investigating the effects of buffer proteins on local calcium concentrations and channel gating. We find transient and stationary elevations of calcium concentrations around active channels and show how they determine release amplitude. Transient calcium domains occur after closing of isolated channels and constitute an important part of the channel's feedback. They cause repeated openings (bursts) and mediate increased release due to Ca(2+) buffering by immobile proteins. Stationary domains occur during prolonged activity of clustered channels, where the spatial proximity of IP(3)Rs produces a distinct [Ca(2+)] scale (0.5-10 microM), which is smaller than channel pore concentrations (>100 microM) but larger than transient levels. While immobile buffer affects transient levels only, mobile buffers in general reduce both transient and stationary domains, giving rise to Ca(2+) evacuation and biphasic modulation of release amplitude. Our findings explain recent experiments in oocytes and provide a general framework for the understanding of calcium signals.


Assuntos
Cálcio/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/química , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Modelos Moleculares , Soluções Tampão , Ativação do Canal Iônico/efeitos dos fármacos , Probabilidade , Estrutura Terciária de Proteína
8.
Phys Rev Lett ; 105(4): 048103, 2010 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-20867887

RESUMO

Using deterministic-stochastic simulations we show that for intracellular calcium puffs the mixing assumption for reactants does not hold within clusters of receptor channels. Consequently, the law of mass action does not apply and useful definitions of averaged calcium concentrations in the cluster are not obvious. Effective reaction kinetics can be derived, however, by separating concentrations for self-coupling of channels and coupling to different channels, thus eliminating detailed balance in the reaction scheme. A minimal Markovian model can be inferred, describing well calcium puffs in neuronal cells and allowing insight into the functioning of calcium puffs.


Assuntos
Sinalização do Cálcio , Modelos Biológicos , Simulação por Computador
9.
Phys Rev E Stat Nonlin Soft Matter Phys ; 79(4 Pt 1): 041923, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19518272

RESUMO

We study the effects of global noise on waves in heterogeneous, spatially clustered, reaction-diffusion systems with possible applications to calcium signaling. We first discuss how clustering of the excitability determines the dynamics by shifting bifurcation points and creating new oscillatory solutions. We then consider the specific situation, where intrinsic noise, due to the smallness of the excitable patches, destroys the global oscillatory state. We show that additional small global fluctuations, however, can partially restore temporal and spatial coherence of the oscillatory signal.


Assuntos
Sinalização do Cálcio/fisiologia , Modelos Biológicos , Periodicidade , Algoritmos , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Espaço Intracelular/metabolismo , Processos Estocásticos
10.
Chaos ; 19(3): 037105, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19792030

RESUMO

We consider different models of inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R) channels in order to fit nuclear membrane patch clamp data of the stationary open probability, mean open time, and mean close time of channels in the Xenopus oocyte. Our results indicate that rather than to treat the tetrameric IP(3)R as four independent and identical subunits, one should assume sequential binding-unbinding processes of Ca(2+) ions and IP(3) messengers. Our simulations also favor the assumption that a channel opens through a conformational transition from a close state to an active state.


Assuntos
Relógios Biológicos/fisiologia , Sinalização do Cálcio/fisiologia , Receptores de Inositol 1,4,5-Trifosfato/fisiologia , Ativação do Canal Iônico/fisiologia , Modelos Biológicos , Oócitos/fisiologia , Oscilometria/métodos , Algoritmos , Animais , Simulação por Computador , Humanos , Dinâmica não Linear , Xenopus laevis/fisiologia
11.
Brain Res ; 890(2): 246-54, 2001 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-11164790

RESUMO

The analysis of the dynamic properties of epileptiform activity in vitro has led to a better understanding of the time course of neural synchronization and seizure states. Nonlinear analysis is thus potentially useful for the prediction of seizure onset. We have used nonlinear analysis methods to investigate the development of activity in the low calcium model of epilepsy in brain slices. This model is particularly interesting since neurons synchronize in the absence of synaptic transmission. The dynamic properties calculated from extracellular recordings of activity were used to analyze the transition to synchronous firing and their relation to neuronal excitability. The global embedding dimension, local dimension and the Lyapunov exponent were calculated from time segments corresponding to the onset, transition and fully developed stages of activity. The analysis was repeated for recordings made in the presence of various levels of DC electric fields to modulate neuronal excitability. The global and local dimensions did not change once activity was first initiated, even in the presence of the electric field. The maximum Lyapunov exponents increased during the onset of activity but decreased when the applied hyperpolarizing electric field was large enough to partially suppress the activity. These findings establish a relationship between neuronal excitability and the maximum Lyapunov exponent, and suggest that the Lyapunov exponent may be used to distinguish between various states of the neural network and might be important in seizure prediction and control.


Assuntos
Potenciais de Ação/fisiologia , Sinalização do Cálcio/fisiologia , Cálcio/deficiência , Epilepsia/fisiopatologia , Hipocampo/fisiopatologia , Neurônios/metabolismo , Dinâmica não Linear , Animais , Estimulação Elétrica , Epilepsia/metabolismo , Hipocampo/citologia , Hipocampo/metabolismo , Neurônios/citologia , Ratos , Ratos Sprague-Dawley
12.
Phys Rev E Stat Nonlin Soft Matter Phys ; 67(3 Pt 1): 031905, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12689099

RESUMO

A two-dimensional model is proposed for intracellular Ca2+ waves, which incorporates both the discrete nature of Ca2+ release sites in the endoplasmic reticulum membrane and the stochastic dynamics of the clustered inositol 1,4,5-triphosphate (IP3) receptors. Depending on the Ca2+ diffusion coefficient and concentration of IP3, various spontaneous Ca2+ patterns, such as calcium puffs, local waves, abortive waves, global oscillation, and tide waves, can be observed. We further investigate the speed of the global waves as a function of the IP3 concentration and the Ca2+ diffusion coefficient and under what conditions the spatially averaged Ca2+ response can be described by a simple set of ordinary differential equations.


Assuntos
Cálcio/metabolismo , Animais , Sítios de Ligação , Canais de Cálcio/metabolismo , Difusão , Relação Dose-Resposta a Droga , Retículo Endoplasmático , Receptores de Inositol 1,4,5-Trifosfato , Modelos Estatísticos , Oócitos/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Xenopus
13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 64(2 Pt 2): 026220, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11497690

RESUMO

Time-series methods for estimating Lyapunov exponents may give a positive exponent when they are applied to the time series of strange nonchaotic systems. Strange nonchaotic systems are characterized by expanding and contracting regions in phase space that result in repeatedly expanding or contracting trajectories. Using time-series methods, the maximum time-series Lyapunov exponent is calculated as an average of the locally most expanding exponents that characterize the divergence of nearby trajectories following a reconstructed attractor over time. A positive exponent is reported by time-series methods for trajectories in an expanding region. While in a converging region, the most expanding dynamics are related to the quasiperiodic driving force. Statistically, a zero exponent related to the quasiperiodic force is obtained through time-series methods within converging regions. As a result, the calculated maximum Lyapunov exponent is positive.

14.
Phys Rev E Stat Nonlin Soft Matter Phys ; 66(5 Pt 2): 056203, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12513582

RESUMO

The phase synchronization (PS) of two Rössler oscillators with time-delayed signal coupling is studied. We find that time delay can always lead to PS even when the delay is very long. Moreover, with the increase of time delay, the coupling strength at the transition to PS undergoes a nearly periodic wave distribution. At some fixed time-delayed signal coupling, a PS region is followed by a non-PS region when the coupling strength increases. However, an increase of the coupling leads to the PS state again. This phenomenon occurs in systems with a relatively large PS transition point.

15.
Phys Rev E Stat Nonlin Soft Matter Phys ; 63(3 Pt 2): 036214, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11308748

RESUMO

We have studied phase synchronization between two identical Rössler oscillators connected in the drive-response configuration by a single phase signal. Before the transition to phase synchronization, the distribution of the time interval between consecutive 2pi jumps shows several sharp peaks. With a strong phase signal coupling, the n:m phase synchronization between the oscillators can be achieved. For the n (not equal) m phase synchronizing state, some values of coupling strength result in a phenomenon characterized by a reduction in the mean amplitude of the response termed amplitude reduction. In these regions, the mean rotation speed of the response remains approximately constant while the locking ratio n:m varies.

16.
Phys Rev E Stat Nonlin Soft Matter Phys ; 64(1 Pt 2): 016212, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11461372

RESUMO

Phase synchronization is studied with a discrete system formed by two coupled map lattices, in which phases are measured in two-dimensional vectors. Simulation results show that by imposing external coupling between the two lattices, phase synchronization can be found in all two-dimensional phase planes between them. When the system is approaching the phase synchronizing state, unstable phase synchronization is observed. This is referred to as intermittent phase synchronization that appears when the trajectories on two interacting phase planes have opposite directions of rotation but with only a small phase difference. The intermittent phase synchronization could also be observed in coupled autonomous systems with diffusive attractors although their phase concepts are inconsistent. Our results show that the intermittent phase synchronization of both discrete and autonomous systems relates to the diffusion or the complexity of the attractors.

17.
Chaos ; 12(1): 100-106, 2002 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12779537

RESUMO

We generalize the n:m phase synchronization between two chaotic oscillators by mutual coupling phase signals. To characterize this phenomenon, we use two coupled oscillators to demonstrate their phase synchronization with amplitudes practically noncorrelated. We take the 1:1 phase synchronization as an example to show the properties of mean frequencies, mean phase difference, and Lyapunov exponents at various values of coupling strength. The phase difference increases with 2pi phase slips below the transition. The scaling rules of the slip near and away from the transition are studied. Furthermore, we demonstrate the transition to a variety of n:m phase synchronizations and analyze the corresponding coupling dynamics. (c) 2002 American Institute of Physics.

18.
Zhonghua Wai Ke Za Zhi ; 37(5): 292-4, 1999 May.
Artigo em Chinês | MEDLINE | ID: mdl-11829843

RESUMO

OBJECTIVE: To investigate the expression of CCK-A receptor and its relation with gallbladder hypomotility in patients with gallstone. METHODS: 20 patients with gallstone and 10 normal subjects were studied and gallbladder emptying function was measured by B ultrasonography. The other 8 patients without gallstone who died of accident were selected as controls for measuring mRNA expression of CCK-A receptor of gallbladder; RT-PCR was used to explore gene expression of CCK-A receptor of gallbladder. RESULTS: The gallbladder motility was significantly impaired in gallstone patients. The patients had lower mRNA expression of CCK-A receptor than control subjects (0.633 +/- 0.167 vs. 0.944 +/- 0.230, P < 0.01), and so did patients with impaired gallbladder motility then those with normal motility (0.544 +/- 0.124 vs. 0.768 +/- 0.131, P < 0.05). Furthermore, the change of expression of CCK-A receptors was markedly correlated with gallbladder emptying (r = 0.925, P < 0.01). CONCLUSIONS: mRNA expression of CCK-A receptor in gallstone patients decreases, which was related to gallbladder hypomotility. The down-regulation of gene expression of CCK-A receptor plays an important role in gallbladder hypomotility in patients with gallstone.


Assuntos
Colecistolitíase/fisiopatologia , Esvaziamento da Vesícula Biliar , Receptor de Colecistocinina A/metabolismo , Colecistolitíase/genética , Expressão Gênica , Humanos , RNA Mensageiro/genética , Receptor de Colecistocinina A/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
19.
Phys Rev E Stat Nonlin Soft Matter Phys ; 85(6 Pt 1): 061911, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23005131

RESUMO

Experiments show a primary role of extracellular potassium concentrations in neuronal hyperexcitability and in the generation of epileptiform bursting and depolarization blocks without synaptic mechanisms. We adopt a physiologically relevant hippocampal CA1 neuron model in a zero-calcium condition to better understand the function of extracellular potassium in neuronal seizurelike activities. The model neuron is surrounded by interstitial space in which potassium ions are able to accumulate. Potassium currents, Na{+}-K{+} pumps, glial buffering, and ion diffusion are regulatory mechanisms of extracellular potassium. We also consider a reduced model with a fixed potassium concentration. The bifurcation structure and spiking frequency of the two models are studied. We show that, besides hyperexcitability and bursting pattern modulation, the potassium dynamics can induce not only bistability but also tristability of different firing patterns. Our results reveal the emergence of the complex behavior of multistability due to the dynamical [K{+}]{o} modulation on neuronal activities.


Assuntos
Potenciais de Ação/fisiologia , Hipocampo/fisiologia , Ativação do Canal Iônico/fisiologia , Modelos Neurológicos , Neurônios/fisiologia , Canais de Potássio/fisiologia , Potássio/metabolismo , Animais , Simulação por Computador , Humanos
20.
J Phys Chem B ; 116(5): 1651-4, 2012 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-22251366

RESUMO

Although the melting of ice is the most ubiquitous phase transition, (pre)melting and the quasi-liquid layer remain a matter of debate, and little is known about the relationship between the thermodynamic properties of ice nanocrystals and their size and dimensionality. Here, we model analytically the size- and dimensionality-dependent melting temperature, premelting temperature, and melting enthalpy of hydrogen-bonded ice nanocrystals. These three thermodynamic parameters are found to increase with increasing size and dimensionality where the size effect is principle while the dimensionality effect is secondary, and the size dependence of premelting temperature almost follows the same trend as that of melting temperature. The model predictions correspond to the available molecular dynamic simulation and experimental results of ice nanoparticles and nanowires. These agreements enable us to determine theoretically the thickness of the quasi-liquid layer for the first time, which is found to be not constant but slightly increase with increasing size and thus accounts for the occurrence of different reported thicknesses of the quasi-liquid layer.


Assuntos
Gelo/análise , Nanopartículas/química , Congelamento , Ligação de Hidrogênio , Termodinâmica
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