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1.
Chembiochem ; : e202400468, 2024 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-39075031

RESUMO

DNA condensates, formed by liquid-liquid phase separation (LLPS), emerge as promising soft matter assemblies for creating artificial cells. The advantages of DNA condensates are their molecular permeability through the surface due to their membrane-less structure and their fluidic property. However, they face challenges in the design of their surface, e.g., unintended fusion and less regulation of permeable molecules. Addressing them, we report surface modification of DNA condensates with DNA origami nanoparticles, employing a Pickering-emulsion strategy. We successfully constructed core-shell structures with DNA origami coatings on DNA condensates and further enhanced the condensate stability toward fusion via connecting DNA origamis by responding to DNA input strands. The 'armoring' prevented the fusion of DNA condensates, enabling the formation of multicellular-like structures of DNA condensates. Moreover, the permeability was altered through the state change from coating to armoring the DNA condensates. The armored DNA condensates have significant potential for constructing artificial cells, offering increased surface stability and selective permeability for small molecules while maintaining compartmentalized space and multicellular organization.

2.
Artigo em Inglês | MEDLINE | ID: mdl-39143666

RESUMO

PURPOSE: The aim of this study was to investigate the utility of native T1 and T2 mapping in the bowel to evaluate disease activity in Crohn disease (CD) using endoscopy as the reference standard. METHODS: This was a prospective study. Magnetic resonance imaging was performed by using a 1.5-T Philips scanner. We used a modified look-locker inversion recovery and a multiecho gradient-spin-echo sequences for single breath-hold native T1 and T2 maps, respectively, for the short-axis image of the intestine, and the measurement at the most severe site was compared with partial Simple Endoscopic Score for Crohn's Disease (pSES-CD, assessed by an expert endoscopist). A pSES-CD ≥ 4 indicated active disease. Statistical analyses were performed using the Student t test, Spearman correlation, and receiver operating characteristic curve analysis. RESULTS: A total of 27 patients (mean age ± standard deviation, 37 ± 18 years; 20 men, 7 women) were included in this study. The native T1 value of active disease was significantly higher than that of inactive disease (1170.8 ± 100.5 milliseconds vs 924.5 ± 95.3 milliseconds; P = 0.018), but the T2 value was not significantly different between active and inactive disease (76.1 ± 7.8 milliseconds vs 69.3 ± 10.9 milliseconds; P = 0.424). A good correlation was found between native T1 value and pSES-CD (ρ = 0.71; P < 0.001) but not between T2 value and pSES-CD (ρ = 0.06; P = 0.790). The area under the receiver operating characteristic curve for differentiating the disease activity was 0.96 (95% confidence interval [CI]: 0.90-1.00) for T1 values and 0.68 (95% confidence interval: 0.41-0.96) for T2 values. CONCLUSIONS: Native T1 mapping could be potentially used as a noninvasive method to differentiate disease activity in patients with CD and may be superior to T2 mapping for this purpose.

3.
J Nucl Cardiol ; 30(5): 1879-1885, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-36918460

RESUMO

BACKGROUND: The aim of this study was to estimate the impact of respiratory and electrocardiogram (ECG)-gated FDG positron emission tomography (PET)/computed tomography (CT) on the diagnosis of cardiac sarcoidosis (CS). METHODS AND RESULTS: Imaging from thirty-one patients was acquired on a PET/CT scanner equipped with a respiratory- and ECG-gating system. Non-gated PET images and three kinds of gated PET/CT images were created from identical list-mode clinical PET data: respiratory-gated PET during expiration (EX), ECG-gated PET at end diastole (ED), and ECG-gated PET at end systole (ES). The maximum standardized uptake value (SUVmax) and cardiac metabolic volume (CMV) were measured, and the locations of FDG accumulation were analyzed using a polar map. The mean SUVmax of the subjects was significantly higher after application of either respiratory-gated or ECG-gated reconstruction. Conversely, the mean CMV was significantly lower following the application of respiratory-gated or ECG-gated reconstruction. The segment showing maximum accumulation was shifted to the adjacent segment in 25.8%, 38.7%, and 41.9% of cases in EX, ED, and ES images, respectively. CONCLUSION: In FDG PET/CT scanning for the diagnosis of CS, gated scanning is likely to increase quantitative accuracy, but the effect depends on the location and synchronization method.


Assuntos
Infecções por Citomegalovirus , Sarcoidose , Humanos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Fluordesoxiglucose F18 , Tomografia por Emissão de Pósitrons/métodos , Eletrocardiografia , Sarcoidose/diagnóstico por imagem
4.
Angew Chem Int Ed Engl ; 62(13): e202218458, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36696593

RESUMO

Loosely bonded ("rattling") atoms with s2 lone pair electrons are usually associated with strong anharmonicity and unexpectedly low thermal conductivity, yet their detailed correlation remains largely unknown. Here we resolve this correlation in thermoelectric InTe by combining chemical bonding analysis, inelastic X-ray and neutron scattering, and first principles phonon calculations. We successfully probe soft low-lying transverse phonons dominated by large In1+ z-axis motions, and their giant anharmonicity. We show that the highly anharmonic phonons arise from the dynamic lone pair expression with unstable occupied antibonding states induced by the covalency between delocalized In1+ 5s2 lone pair electrons and Te 5p states. This work pinpoints the microscopic origin of strong anharmonicity driven by rattling atoms with stereochemical lone pair activity, important for designing efficient materials for thermoelectric energy conversion.

5.
J Chem Phys ; 157(15): 154504, 2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36272787

RESUMO

Inelastic x-ray scattering spectra of four organic liquids, n-hexane, cyclohexane, ethylene glycol dimethyl ether, and 1,4-dioxane, were measured, and the sound velocity in the nm-1 wavenumber and meV energy regimes was determined. Compared with the corresponding values in the hydrodynamic limit, the sound velocity in the nm-1 regime was faster, and the positive dispersion of the longitudinal modulus was stronger in liquids composed of ring structures (cyclohexane and 1,4-dioxane) than in those of linear chain structures (n-hexane and ethylene glycol dimethyl ether). Molecular dynamics simulation of n-hexane and cyclohexane was also performed. The difference in the positive dispersion of the longitudinal modulus was reproduced by simulation, and it was elucidated by the difference in the longitudinal modulus in the q = 0 limit and the THz frequency regime. The excess part of the longitudinal modulus from the hydrodynamic limit was further divided into various contributions, and the smaller excess modulus of n-hexane was mainly ascribed to two reasons. The first one is that the shear modulus of n-hexane is smaller in the THz regime, and the second one is that the positive dispersion of the bulk modulus due to the vibrational energy relaxation is weaker. The second mechanism was further interpreted in terms of the fast vibrational energy relaxation of intramolecular modes associated with the chain deformation of n-hexane.

6.
J Synchrotron Radiat ; 28(Pt 3): 756-768, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33949984

RESUMO

The detailed fabrication and performance of the temperature-gradient analyzers that were simulated by Ishikawa & Baron [(2010). J. Synchrotron Rad. 17, 12-24] are described and extended to include both quadratic and 2D gradients. The application of a temperature gradient compensates for geometric contributions to the energy resolution while allowing collection of a large solid angle, ∼50 mrad × 50 mrad, of scattered radiation. In particular, when operating relatively close to backscattering, π/2 - θB = 1.58 mrad, the application of a gradient of 1.32 K per 80 mm improves the measured total resolution from 60 to 25 meV at the full width at half-maximum, while when operating further from backscattering, π/2 - θB = 6.56 mrad, improvement from 330 to 32 meV is observed using a combination of a gradient of 6.2 K per 80 mm and dispersion compensation with a position-sensitive detector. In both cases, the operating energy was 15.8 keV and the incident bandwidth was 22 meV. Notably, the use of a temperature gradient allows a relatively large clearance at the sample, permitting installation of more complicated sample environments.

7.
J Synchrotron Radiat ; 28(Pt 3): 804-811, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33949988

RESUMO

Several different ways of measuring the energy resolution for meV-resolved inelastic X-ray scattering (IXS) are compared: using scattering from poly(methyl methacrylate), PMMA, using scattering from borosilicate glass (Tempax), and using powder diffraction from aluminium. All of these methods provide a reasonable first approximation to the energy resolution, but, also, in all cases, inelastic contributions appear over some range of energy transfers. Over a range of ±15 meV energy transfer there is good agreement between the measurements of PMMA and Tempax at low temperature, and room-temperature powder diffraction from aluminium, so we consider this to be a good indication of the true resolution of our ∼1.3 meV spectrometer. The resolution over a wider energy range is self-consistently determined using the temperature, momentum and sample dependence of the measured response. The inelastic contributions from the PMMA and Tempax, and their dependence on momentum transfer and temperature, are then quantitatively investigated. The resulting data allow us to determine the resolution of our multi-analyzer array efficiently using a single scan. The importance of this procedure is demonstrated by showing that the results of the analysis of a spectrum from a glass are changed by using the properly deconvolved resolution function. The impact of radiation damage on the scattering from PMMA and Tempax is also discussed.

8.
Phys Rev Lett ; 125(25): 256001, 2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-33416384

RESUMO

Molecular-scale dynamics in sub- to supercritical water is studied with inelastic x-ray scattering and molecular dynamics simulations. The obtained longitudinal current correlation spectra can be decomposed into two main components: a low-frequency (LF), gaslike component and a high-frequency (HF) component arising from the O-O stretching mode between hydrogen-bonded molecules, reminiscent of the longitudinal acoustic mode in ambient water. With increasing temperature, the hydrogen-bond network diminishes and the spectral weight shifts from HF to LF, leading to a transition from liquid- to gaslike dynamics with rapid changes around the Widom line.

9.
Phys Rev Lett ; 124(16): 165701, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32383924

RESUMO

The density of liquid iron has been determined up to 116 GPa and 4350 K via static compression experiments following an innovative analysis of diffuse scattering from liquid. The longitudinal sound velocity was also obtained to 45 GPa and 2700 K based on inelastic x-ray scattering measurements. Combining these results with previous shock-wave data, we determine a thermal equation of state for liquid iron. It indicates that Earth's outer core exhibits 7.5%-7.6% density deficit, 3.7%-4.4% velocity excess, and an almost identical adiabatic bulk modulus, with respect to liquid iron.

10.
Angew Chem Int Ed Engl ; 58(43): 15299-15303, 2019 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-31411794

RESUMO

Bio-inspired functional microcapsules have attracted increasing attention in many fields from physical/chemical science to artificial-cell engineering. Although particle-stabilised microcapsules are advantageous for their stability and functionalisation potential, versatile methods for their functionalisation are desired to expand their possibilities. This study reports a water-in-oil microdroplet stabilised with amphiphilic DNA origami nanoplates. By utilising DNA nanotechnology, DNA nanoplates were designed as a nanopore device for ion transportation and to stabilise the oil-water interface. Microscopic examination revealed the microcapsule formed by the accumulation of amphiphilic DNA nanoplates at the oil-water interface. Ion current measurements revealed the nanoplate pores functioned as channel to transport ions. These findings provide a general strategy for the programmable design of microcapsules to engineer artificial cells and molecular robots.


Assuntos
DNA/química , Nanoporos , Nanoestruturas/química , Colesterol/química , Fluoresceínas/química , Microscopia de Força Atômica , Microscopia Confocal , Óleos/química , Polietilenoglicóis/química , Água/química
11.
J Biol Chem ; 291(48): 25096-25105, 2016 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-27758856

RESUMO

Familial amyloidotic polyneuropathy (FAP) is a systemic amyloidosis mainly caused by amyloidogenic transthyretin (ATTR). This incurable disease causes death ∼10 years after onset. Although it has been widely accepted that conformational change of the monomeric form of transthyretin (TTR) is very important for amyloid formation and deposition in the organs, no effective therapy targeting this step is available. In this study, we generated a mouse monoclonal antibody, T24, that recognized the cryptic epitope of conformationally changed TTR. T24 inhibited TTR accumulation in FAP model rats, which expressed human ATTR V30M in various tissues and exhibited non-fibrillar deposits of ATTR in the gastrointestinal tracts. Additionally, humanized T24 (RT24) inhibited TTR fibrillation and promoted macrophage phagocytosis of aggregated TTR. This antibody did not recognize normal serum TTR functioning properly in the blood. These results demonstrate that RT24 would be an effective novel therapeutic antibody for FAP.


Assuntos
Neuropatias Amiloides Familiares/tratamento farmacológico , Neuropatias Amiloides Familiares/imunologia , Anticorpos Monoclonais Murinos/imunologia , Macrófagos/imunologia , Fagocitose/efeitos dos fármacos , Pré-Albumina/imunologia , Neuropatias Amiloides Familiares/patologia , Animais , Anticorpos Monoclonais Murinos/uso terapêutico , Feminino , Humanos , Macrófagos/patologia , Masculino , Camundongos , Ratos
12.
Chemphyschem ; 18(11): 1470-1474, 2017 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-27781370

RESUMO

Reversible dynamic control of structure is a significant challenge in molecular nanotechnology. Previously, we have reported a mechanically induced continuous (analog) conformational variation in an amphiphilic binaphthyl, where closing of molecular pliers was achieved by compression of a molecular monolayer composed of these molecules at the air-water interface. In this work we report that a phase transition induced by an applied mechanical stress enables discontinuous digital (1/0) opening of simple binaphthyl molecular pliers. A lipid matrix at the air-water interface promotes the formation of quasi-stable nanocrystals, in which binaphthyl molecules have an open transoid configuration. The crystallization/dissolution of quasi-stable binaphthyl crystals with accompanying conformational change is reversible and repeatable.


Assuntos
Naftalenos/química , Fenômenos Mecânicos , Conformação Molecular , Transição de Fase
13.
BMC Infect Dis ; 17(1): 330, 2017 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-28482818

RESUMO

BACKGROUND: In Japan, approximately 0.9% and 1% of the whole population are infected with HBV and HCV, respectively. Doctors from departments other than gastroenterology often order viral hepatitis tests before an invasive examination or an operation. However, the notification of positive results to the patients and linkage to care is not appropriately performed. The in-hospital alert system was constructed to promote the notification and referral to gastroenterologists for patients with positive viral hepatitis tests, and its efficacy was evaluated. METHODS: The patients who tested HBsAg and anti-HCV antibody by chemiluminescent enzyme immunoassays and chemiluminescent immunoassays were investigated for whether they were notified of the positive results and if they were referred to gastroenterologists at our hospital. The notification and referral rate was compared before (from January to December 2014) and after the introduction of the alert system (from February to September 2016). RESULTS: HBsAg-positive rate was 1.1% (69/6543) before the introduction of the alert system and 0.8% (41/5403) after it. The notification rate has significantly improved from 46% to 73% (p = 0.0061) and the referral rate has improved from 16% to 27%, while not significant. Positive rate of anti-HCV antibody was 2.1% (139/6481) before the introduction of the alert system and 2.4% (128/5322) after it. The rate of notification and referral has significantly improved from 35% to 62% (p < 0.0001) and from 6% to 23% (p < 0.0001), respectively. CONCLUSIONS: The in-hospital alert system increased the rates of notification and referral of the patients with positive viral hepatitis tests. Enlightenment of doctors other than gastroenterologists on viral hepatitis and cooperation of medical staffs would be helpful to improve the notification and referral rates.


Assuntos
Hepatite B/diagnóstico , Hepatite C/diagnóstico , Sistemas de Comunicação no Hospital/organização & administração , Gastroenterologistas , Hepatite B/epidemiologia , Antígenos de Superfície da Hepatite B/sangue , Hepatite C/epidemiologia , Anticorpos Anti-Hepatite C/sangue , Administração Hospitalar/métodos , Hospitais , Humanos , Japão/epidemiologia , Encaminhamento e Consulta/estatística & dados numéricos
14.
J Immunol ; 195(2): 726-35, 2015 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-26041539

RESUMO

Antitumor immunity is augmented by cytotoxic lymphodepletion therapies. Adoptively transferred naive and effector T cells proliferate extensively and show enhanced antitumor effects in lymphopenic recipients. Although the impact of lymphodepletion on transferred donor T cells has been well evaluated, its influence on recipient T cells is largely unknown. The current study demonstrates that both regulatory T cells (Tregs) and effector CD8(+) T cells from lymphopenic recipients play critical roles in the development of antitumor immunity after lymphodepletion. Cyclophosphamide (CPA) treatment depleted lymphocytes more efficiently than other cytotoxic agents; however, the percentage of CD4(+)CD25(+) Foxp3(+) Tregs was significantly increased in CPA-treated lymphopenic mice. Depletion of these chemoresistant Tregs following CPA treatment and transfer of naive CD4(+) T cells augmented the antitumor immunity and significantly suppressed tumor progression. Further analyses revealed that recipient CD8(+) T cells were responsible for this augmentation. Using Rag2(-/-) mice or depletion of recipient CD8(+) T cells after CPA treatment abrogated the augmentation of antitumor effects in CPA-treated reconstituted mice. The transfer of donor CD4(+) T cells enhanced the proliferation of CD8(+) T cells and the priming of tumor-specific CD8(+) T cells originating from the lymphopenic recipients. These results highlight the importance of the recipient cells surviving cytotoxic regimens in cancer immunotherapies.


Assuntos
Citotoxinas/farmacologia , Fibrossarcoma/terapia , Depleção Linfocítica , Linfopenia/terapia , Linfócitos T Citotóxicos/imunologia , Linfócitos T Reguladores/imunologia , Transferência Adotiva , Animais , Cisplatino/farmacologia , Ciclofosfamida/farmacologia , Desoxicitidina/análogos & derivados , Desoxicitidina/farmacologia , Resistência a Medicamentos/imunologia , Etoposídeo/farmacologia , Feminino , Fibrossarcoma/induzido quimicamente , Fibrossarcoma/imunologia , Fibrossarcoma/patologia , Linfonodos/imunologia , Linfonodos/patologia , Linfopenia/induzido quimicamente , Linfopenia/imunologia , Linfopenia/patologia , Metilcolantreno , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Paclitaxel/farmacologia , Linfócitos T Citotóxicos/efeitos dos fármacos , Linfócitos T Citotóxicos/patologia , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/patologia , Células Tumorais Cultivadas , Vidarabina/análogos & derivados , Vidarabina/farmacologia , Irradiação Corporal Total , Gencitabina
15.
BMC Cancer ; 16: 222, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26979596

RESUMO

BACKGROUND: Nephrotoxicity is the major side effect that limits the dose of cisplatin that can be safely administered, and it is a clinical problem in cancer patients who received cisplatin combination chemotherapy. Recent evidence has demonstrated that patients with chronic kidney disease (CKD) have an increased risk of developing acute kidney injury (AKI). The present study was conducted to evaluate the prevalence of CKD risk factors in patients who received cisplatin and to assess the correlation between CKD risk factors and cisplatin-induced AKI. METHODS: We retrospectively analyzed 84 patients treated with cisplatin combination chemotherapy for thoracic malignancies. AKI was defined as a decrease in the estimated glomerular filtration rate (eGFR) > 25% from base line, an increase in the serum creatinine (sCre) level of > 0.3 mg/dl or ≥ 1.5 times the baseline level. RESULTS: Eighty of the 84 patients (95.2%) had at least one risk factor for CKD. All enrolled patients received cisplatin with hydration, magnesium supplementation and mannitol. Cisplatin-induced AKI was observed in 18 patients (21.4%). Univariate analysis revealed that cardiac disease and use of non-steroidal anti-inflammatory drugs (NSAIDs) were associated with cisplatin-induced nephrotoxicity (odds ratios [OR] 6 and 3.56, 95% confidence intervals [CI] 1.21-29.87 and 1.11-11.39, p = 0.04 and p = 0.04, respectively). Multivariate analysis revealed that cisplatin nephrotoxicity occurred significantly more often in patients with both risk factors (OR 13.64, 95% CI 1.11-326.83, p = 0.04). Patients with more risk factors for CKD tended to have a greater risk of developing cisplatin-induced AKI. CONCLUSIONS: We should consider avoiding administration of cisplatin to patients with CKD risk factors, particularly cardiac disease and NSAID use.


Assuntos
Injúria Renal Aguda/patologia , Cisplatino/efeitos adversos , Insuficiência Renal Crônica/patologia , Neoplasias Torácicas/tratamento farmacológico , Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/tratamento farmacológico , Adulto , Idoso , Anti-Inflamatórios não Esteroides/administração & dosagem , Cisplatino/administração & dosagem , Creatinina/sangue , Quimioterapia Combinada , Feminino , Taxa de Filtração Glomerular/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Insuficiência Renal Crônica/tratamento farmacológico , Fatores de Risco , Neoplasias Torácicas/complicações , Neoplasias Torácicas/patologia
16.
J Neurosci ; 34(14): 5044-53, 2014 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-24695722

RESUMO

Learning is a process of plastic adaptation through which a neural circuit generates a more preferable outcome; however, at a microscopic level, little is known about how synaptic activity is patterned into a desired configuration. Here, we report that animals can generate a specific form of synaptic activity in a given neuron in the hippocampus. In awake, head-restricted mice, we applied electrical stimulation to the lateral hypothalamus, a reward-associated brain region, when whole-cell patch-clamped CA1 neurons exhibited spontaneous synaptic activity that met preset criteria. Within 15 min, the mice learned to generate frequently the excitatory synaptic input pattern that satisfied the criteria. This reinforcement learning of synaptic activity was not observed for inhibitory input patterns. When a burst unit activity pattern was conditioned in paired and nonpaired paradigms, the frequency of burst-spiking events increased and decreased, respectively. The burst reinforcement occurred in the conditioned neuron but not in other adjacent neurons; however, ripple field oscillations were concomitantly reinforced. Neural conditioning depended on activation of NMDA receptors and dopamine D1 receptors. Acutely stressed mice and depression model mice that were subjected to forced swimming failed to exhibit the neural conditioning. This learning deficit was rescued by repetitive treatment with fluoxetine, an antidepressant. Therefore, internally motivated animals are capable of routing an ongoing action potential series into a specific neural pathway of the hippocampal network.


Assuntos
Potenciais de Ação/fisiologia , Condicionamento Operante/fisiologia , Hipocampo/citologia , Neurônios/fisiologia , Sinapses/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Maleato de Dizocilpina/farmacologia , Estimulação Elétrica , Antagonistas de Aminoácidos Excitatórios/farmacologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Região Hipotalâmica Lateral/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Vias Neurais/efeitos dos fármacos , Vias Neurais/fisiologia , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Reforço Psicológico , Natação/psicologia , Sinapses/efeitos dos fármacos , Vibrissas/inervação , Vigília
17.
J Synchrotron Radiat ; 22(1): 3-9, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25537581

RESUMO

The use of temperature-gradient analyzers for non-resonant high-resolution inelastic X-ray scattering is investigated. The gradient compensates for geometrical broadening of the energy resolution by adjusting the lattice spacing of the analyzer crystal. Applying a ∼ 12 mK temperature gradient across a 9.5 cm analyzer, resolutions of 0.75 (2) meV FWHM at 25.7 keV for Si(13 13 13) and 1.25(2) meV at 21.7 keV for Si(11 11 11) were measured, while retaining large (250 mm) clearance between the sample position and detector, and reasonable (9.3 mrad × 8.8 mrad) analyzer acceptance. The temperature control and stability are discussed.

18.
Angew Chem Int Ed Engl ; 54(31): 8988-91, 2015 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-26073773

RESUMO

Gradual and reversible tuning of the torsion angle of an amphiphilic chiral binaphthyl, from -90° to -80°, was achieved by application of a mechanical force to its molecular monolayer at the air-water interface. This 2D interface was an ideal location for mechanochemistry for molecular tuning and its experimental and theoretical analysis, since this lowered dimension enables high orientation of molecules and large variation in the area. A small mechanical energy (<1 kcal mol(-1) ) was applied to the monolayer, causing a large variation (>50 %) in the area of the monolayer and modification of binaphthyl conformation. Single-molecule simulations revealed that mechanical energy was converted proportionally to torsional energy. Molecular dynamics simulations of the monolayer indicated that the global average torsion angle of a monolayer was gradually shifted.

19.
Phys Chem Chem Phys ; 16(21): 9713-46, 2014 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-24562603

RESUMO

Porphyrins and related families of molecules are important organic modules as has been reflected in the award of the Nobel Prizes in Chemistry in 1915, 1930, 1961, 1962, 1965, and 1988 for work on porphyrin-related biological functionalities. The porphyrin core can be synthetically modified by introduction of various functional groups and other elements, allowing creation of numerous types of porphyrin derivatives. This feature makes porphyrins extremely useful molecules especially in combination with their other interesting photonic, electronic and magnetic properties, which in turn is reflected in their diverse signal input-output functionalities based on interactions with other molecules and external stimuli. Therefore, porphyrins and related macrocycles play a preeminent role in sensing applications involving chromophores. In this review, we discuss recent developments in porphyrin-based sensing applications in conjunction with the new advanced concept of nanoarchitectonics, which creates functional nanostructures based on a profound understanding of mutual interactions between the individual nanostructures and their arbitrary arrangements. Following a brief explanation of the basics of porphyrin chemistry and physics, recent examples in the corresponding fields are discussed according to a classification based on physical modes of detection including optical detection (absorption/photoluminescence spectroscopy and energy and electron transfer processes), other spectral modes (circular dichroism, plasmon and nuclear magnetic resonance), electronic and electrochemical modes, and other sensing modes.

20.
Cereb Cortex ; 23(2): 293-304, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22314044

RESUMO

Cortical synaptic strengths vary substantially from synapse to synapse and exhibit a skewed distribution with a small fraction of synapses generating extremely large depolarizations. Using multiple whole-cell recordings from rat hippocampal CA3 pyramidal cells, we found that the amplitude of unitary excitatory postsynaptic conductances approximates a lognormal distribution and that in the presence of synaptic background noise, the strongest fraction of synapses could trigger action potentials in postsynaptic neurons even with single presynaptic action potentials, a phenomenon termed interpyramid spike transmission (IpST). The IpST probability reached 80%, depending on the network state. To examine how IpST impacts network dynamics, we simulated a recurrent neural network embedded with a few potent synapses. This network, unlike many classical neural networks, exhibited distinctive behaviors resembling cortical network activity in vivo. These behaviors included the following: 1) infrequent ongoing activity, 2) firing rates of individual neurons approximating a lognormal distribution, 3) asynchronous spikes among neurons, 4) net balance between excitation and inhibition, 5) network activity patterns that was robust against external perturbation, 6) responsiveness even to a single spike of a single excitatory neuron, and 7) precise firing sequences. Thus, IpST captures a surprising number of recent experimental findings in vivo. We propose that an unequally biased distribution with a few select strong synapses helps stabilize sparse neuronal activity, thereby reducing the total spiking cost, enhancing the circuit responsiveness, and ensuring reliable information transfer.


Assuntos
Potenciais de Ação/fisiologia , Região CA3 Hipocampal/fisiologia , Rede Nervosa/fisiologia , Transmissão Sináptica/fisiologia , Animais , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Masculino , Técnicas de Patch-Clamp , Ratos , Ratos Wistar
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